1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 *	Routines having to do with the 'struct sk_buff' memory handlers.
   4 *
   5 *	Authors:	Alan Cox <alan@lxorguk.ukuu.org.uk>
   6 *			Florian La Roche <rzsfl@rz.uni-sb.de>
   7 *
   8 *	Fixes:
   9 *		Alan Cox	:	Fixed the worst of the load
  10 *					balancer bugs.
  11 *		Dave Platt	:	Interrupt stacking fix.
  12 *	Richard Kooijman	:	Timestamp fixes.
  13 *		Alan Cox	:	Changed buffer format.
  14 *		Alan Cox	:	destructor hook for AF_UNIX etc.
  15 *		Linus Torvalds	:	Better skb_clone.
  16 *		Alan Cox	:	Added skb_copy.
  17 *		Alan Cox	:	Added all the changed routines Linus
  18 *					only put in the headers
  19 *		Ray VanTassle	:	Fixed --skb->lock in free
  20 *		Alan Cox	:	skb_copy copy arp field
  21 *		Andi Kleen	:	slabified it.
  22 *		Robert Olsson	:	Removed skb_head_pool
  23 *
  24 *	NOTE:
  25 *		The __skb_ routines should be called with interrupts
  26 *	disabled, or you better be *real* sure that the operation is atomic
  27 *	with respect to whatever list is being frobbed (e.g. via lock_sock()
  28 *	or via disabling bottom half handlers, etc).
  29 */
  30
  31/*
  32 *	The functions in this file will not compile correctly with gcc 2.4.x
  33 */
  34
  35#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  36
  37#include <linux/module.h>
  38#include <linux/types.h>
  39#include <linux/kernel.h>
  40#include <linux/mm.h>
  41#include <linux/interrupt.h>
  42#include <linux/in.h>
  43#include <linux/inet.h>
  44#include <linux/slab.h>
  45#include <linux/tcp.h>
  46#include <linux/udp.h>
  47#include <linux/sctp.h>
  48#include <linux/netdevice.h>
  49#ifdef CONFIG_NET_CLS_ACT
  50#include <net/pkt_sched.h>
  51#endif
  52#include <linux/string.h>
  53#include <linux/skbuff.h>
  54#include <linux/splice.h>
  55#include <linux/cache.h>
  56#include <linux/rtnetlink.h>
  57#include <linux/init.h>
  58#include <linux/scatterlist.h>
  59#include <linux/errqueue.h>
  60#include <linux/prefetch.h>
  61#include <linux/if_vlan.h>
  62#include <linux/mpls.h>
  63#include <linux/kcov.h>
  64
  65#include <net/protocol.h>
  66#include <net/dst.h>
  67#include <net/sock.h>
  68#include <net/checksum.h>
  69#include <net/ip6_checksum.h>
  70#include <net/xfrm.h>
  71#include <net/mpls.h>
  72#include <net/mptcp.h>
  73#include <net/page_pool.h>
  74
  75#include <linux/uaccess.h>
  76#include <trace/events/skb.h>
  77#include <linux/highmem.h>
  78#include <linux/capability.h>
  79#include <linux/user_namespace.h>
  80#include <linux/indirect_call_wrapper.h>
  81
  82#include "datagram.h"
  83
  84struct kmem_cache *skbuff_head_cache __ro_after_init;
  85static struct kmem_cache *skbuff_fclone_cache __ro_after_init;
  86#ifdef CONFIG_SKB_EXTENSIONS
  87static struct kmem_cache *skbuff_ext_cache __ro_after_init;
  88#endif
  89int sysctl_max_skb_frags __read_mostly = MAX_SKB_FRAGS;
  90EXPORT_SYMBOL(sysctl_max_skb_frags);
  91
  92/**
  93 *	skb_panic - private function for out-of-line support
  94 *	@skb:	buffer
  95 *	@sz:	size
  96 *	@addr:	address
  97 *	@msg:	skb_over_panic or skb_under_panic
  98 *
  99 *	Out-of-line support for skb_put() and skb_push().
 100 *	Called via the wrapper skb_over_panic() or skb_under_panic().
 101 *	Keep out of line to prevent kernel bloat.
 102 *	__builtin_return_address is not used because it is not always reliable.
 103 */
 104static void skb_panic(struct sk_buff *skb, unsigned int sz, void *addr,
 105		      const char msg[])
 106{
 107	pr_emerg("%s: text:%px len:%d put:%d head:%px data:%px tail:%#lx end:%#lx dev:%s\n",
 108		 msg, addr, skb->len, sz, skb->head, skb->data,
 109		 (unsigned long)skb->tail, (unsigned long)skb->end,
 110		 skb->dev ? skb->dev->name : "<NULL>");
 111	BUG();
 112}
 113
 114static void skb_over_panic(struct sk_buff *skb, unsigned int sz, void *addr)
 115{
 116	skb_panic(skb, sz, addr, __func__);
 117}
 118
 119static void skb_under_panic(struct sk_buff *skb, unsigned int sz, void *addr)
 120{
 121	skb_panic(skb, sz, addr, __func__);
 122}
 123
 124#define NAPI_SKB_CACHE_SIZE	64
 125#define NAPI_SKB_CACHE_BULK	16
 126#define NAPI_SKB_CACHE_HALF	(NAPI_SKB_CACHE_SIZE / 2)
 
 
 
 
 
 
 127
 128struct napi_alloc_cache {
 129	struct page_frag_cache page;
 130	unsigned int skb_count;
 131	void *skb_cache[NAPI_SKB_CACHE_SIZE];
 132};
 133
 134static DEFINE_PER_CPU(struct page_frag_cache, netdev_alloc_cache);
 135static DEFINE_PER_CPU(struct napi_alloc_cache, napi_alloc_cache);
 
 
 
 
 
 
 
 136
 137static void *__alloc_frag_align(unsigned int fragsz, gfp_t gfp_mask,
 138				unsigned int align_mask)
 139{
 140	struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
 
 
 
 141
 142	return page_frag_alloc_align(&nc->page, fragsz, gfp_mask, align_mask);
 143}
 144
 145void *__napi_alloc_frag_align(unsigned int fragsz, unsigned int align_mask)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 146{
 147	fragsz = SKB_DATA_ALIGN(fragsz);
 
 
 
 
 148
 149	return __alloc_frag_align(fragsz, GFP_ATOMIC, align_mask);
 150}
 151EXPORT_SYMBOL(__napi_alloc_frag_align);
 152
 153void *__netdev_alloc_frag_align(unsigned int fragsz, unsigned int align_mask)
 154{
 155	struct page_frag_cache *nc;
 156	void *data;
 157
 158	fragsz = SKB_DATA_ALIGN(fragsz);
 159	if (in_irq() || irqs_disabled()) {
 160		nc = this_cpu_ptr(&netdev_alloc_cache);
 161		data = page_frag_alloc_align(nc, fragsz, GFP_ATOMIC, align_mask);
 162	} else {
 163		local_bh_disable();
 164		data = __alloc_frag_align(fragsz, GFP_ATOMIC, align_mask);
 165		local_bh_enable();
 166	}
 167	return data;
 168}
 169EXPORT_SYMBOL(__netdev_alloc_frag_align);
 170
 171static struct sk_buff *napi_skb_cache_get(void)
 172{
 173	struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
 174	struct sk_buff *skb;
 
 
 
 
 
 
 
 
 
 
 
 
 175
 176	if (unlikely(!nc->skb_count))
 177		nc->skb_count = kmem_cache_alloc_bulk(skbuff_head_cache,
 178						      GFP_ATOMIC,
 179						      NAPI_SKB_CACHE_BULK,
 180						      nc->skb_cache);
 181	if (unlikely(!nc->skb_count))
 182		return NULL;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 183
 184	skb = nc->skb_cache[--nc->skb_count];
 185	kasan_unpoison_object_data(skbuff_head_cache, skb);
 
 
 
 
 
 186
 
 
 
 187	return skb;
 
 
 
 
 188}
 
 189
 190/* Caller must provide SKB that is memset cleared */
 191static void __build_skb_around(struct sk_buff *skb, void *data,
 192			       unsigned int frag_size)
 193{
 194	struct skb_shared_info *shinfo;
 195	unsigned int size = frag_size ? : ksize(data);
 196
 197	size -= SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
 198
 199	/* Assumes caller memset cleared SKB */
 200	skb->truesize = SKB_TRUESIZE(size);
 201	refcount_set(&skb->users, 1);
 202	skb->head = data;
 203	skb->data = data;
 204	skb_reset_tail_pointer(skb);
 205	skb->end = skb->tail + size;
 206	skb->mac_header = (typeof(skb->mac_header))~0U;
 207	skb->transport_header = (typeof(skb->transport_header))~0U;
 208
 209	/* make sure we initialize shinfo sequentially */
 210	shinfo = skb_shinfo(skb);
 211	memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
 212	atomic_set(&shinfo->dataref, 1);
 213
 214	skb_set_kcov_handle(skb, kcov_common_handle());
 215}
 216
 217/**
 218 * __build_skb - build a network buffer
 219 * @data: data buffer provided by caller
 220 * @frag_size: size of data, or 0 if head was kmalloced
 221 *
 222 * Allocate a new &sk_buff. Caller provides space holding head and
 223 * skb_shared_info. @data must have been allocated by kmalloc() only if
 224 * @frag_size is 0, otherwise data should come from the page allocator
 225 *  or vmalloc()
 226 * The return is the new skb buffer.
 227 * On a failure the return is %NULL, and @data is not freed.
 228 * Notes :
 229 *  Before IO, driver allocates only data buffer where NIC put incoming frame
 230 *  Driver should add room at head (NET_SKB_PAD) and
 231 *  MUST add room at tail (SKB_DATA_ALIGN(skb_shared_info))
 232 *  After IO, driver calls build_skb(), to allocate sk_buff and populate it
 233 *  before giving packet to stack.
 234 *  RX rings only contains data buffers, not full skbs.
 235 */
 236struct sk_buff *__build_skb(void *data, unsigned int frag_size)
 237{
 238	struct sk_buff *skb;
 239
 240	skb = kmem_cache_alloc(skbuff_head_cache, GFP_ATOMIC);
 241	if (unlikely(!skb))
 242		return NULL;
 243
 244	memset(skb, 0, offsetof(struct sk_buff, tail));
 245	__build_skb_around(skb, data, frag_size);
 246
 247	return skb;
 248}
 249
 250/* build_skb() is wrapper over __build_skb(), that specifically
 251 * takes care of skb->head and skb->pfmemalloc
 252 * This means that if @frag_size is not zero, then @data must be backed
 253 * by a page fragment, not kmalloc() or vmalloc()
 254 */
 255struct sk_buff *build_skb(void *data, unsigned int frag_size)
 256{
 257	struct sk_buff *skb = __build_skb(data, frag_size);
 258
 259	if (skb && frag_size) {
 260		skb->head_frag = 1;
 261		if (page_is_pfmemalloc(virt_to_head_page(data)))
 262			skb->pfmemalloc = 1;
 263	}
 264	return skb;
 265}
 266EXPORT_SYMBOL(build_skb);
 267
 268/**
 269 * build_skb_around - build a network buffer around provided skb
 270 * @skb: sk_buff provide by caller, must be memset cleared
 271 * @data: data buffer provided by caller
 272 * @frag_size: size of data, or 0 if head was kmalloced
 273 */
 274struct sk_buff *build_skb_around(struct sk_buff *skb,
 275				 void *data, unsigned int frag_size)
 276{
 277	if (unlikely(!skb))
 278		return NULL;
 279
 280	__build_skb_around(skb, data, frag_size);
 281
 282	if (frag_size) {
 283		skb->head_frag = 1;
 284		if (page_is_pfmemalloc(virt_to_head_page(data)))
 285			skb->pfmemalloc = 1;
 286	}
 287	return skb;
 288}
 289EXPORT_SYMBOL(build_skb_around);
 290
 291/**
 292 * __napi_build_skb - build a network buffer
 293 * @data: data buffer provided by caller
 294 * @frag_size: size of data, or 0 if head was kmalloced
 295 *
 296 * Version of __build_skb() that uses NAPI percpu caches to obtain
 297 * skbuff_head instead of inplace allocation.
 298 *
 299 * Returns a new &sk_buff on success, %NULL on allocation failure.
 300 */
 301static struct sk_buff *__napi_build_skb(void *data, unsigned int frag_size)
 302{
 303	struct sk_buff *skb;
 304
 305	skb = napi_skb_cache_get();
 306	if (unlikely(!skb))
 307		return NULL;
 308
 309	memset(skb, 0, offsetof(struct sk_buff, tail));
 310	__build_skb_around(skb, data, frag_size);
 
 
 
 311
 312	return skb;
 313}
 314
 315/**
 316 * napi_build_skb - build a network buffer
 317 * @data: data buffer provided by caller
 318 * @frag_size: size of data, or 0 if head was kmalloced
 319 *
 320 * Version of __napi_build_skb() that takes care of skb->head_frag
 321 * and skb->pfmemalloc when the data is a page or page fragment.
 322 *
 323 * Returns a new &sk_buff on success, %NULL on allocation failure.
 324 */
 325struct sk_buff *napi_build_skb(void *data, unsigned int frag_size)
 326{
 327	struct sk_buff *skb = __napi_build_skb(data, frag_size);
 328
 329	if (likely(skb) && frag_size) {
 330		skb->head_frag = 1;
 331		skb_propagate_pfmemalloc(virt_to_head_page(data), skb);
 332	}
 333
 334	return skb;
 335}
 336EXPORT_SYMBOL(napi_build_skb);
 337
 338/*
 339 * kmalloc_reserve is a wrapper around kmalloc_node_track_caller that tells
 340 * the caller if emergency pfmemalloc reserves are being used. If it is and
 341 * the socket is later found to be SOCK_MEMALLOC then PFMEMALLOC reserves
 342 * may be used. Otherwise, the packet data may be discarded until enough
 343 * memory is free
 344 */
 345static void *kmalloc_reserve(size_t size, gfp_t flags, int node,
 346			     bool *pfmemalloc)
 347{
 348	void *obj;
 349	bool ret_pfmemalloc = false;
 350
 351	/*
 352	 * Try a regular allocation, when that fails and we're not entitled
 353	 * to the reserves, fail.
 354	 */
 355	obj = kmalloc_node_track_caller(size,
 356					flags | __GFP_NOMEMALLOC | __GFP_NOWARN,
 357					node);
 358	if (obj || !(gfp_pfmemalloc_allowed(flags)))
 359		goto out;
 360
 361	/* Try again but now we are using pfmemalloc reserves */
 362	ret_pfmemalloc = true;
 363	obj = kmalloc_node_track_caller(size, flags, node);
 364
 365out:
 366	if (pfmemalloc)
 367		*pfmemalloc = ret_pfmemalloc;
 368
 369	return obj;
 370}
 371
 372/* 	Allocate a new skbuff. We do this ourselves so we can fill in a few
 373 *	'private' fields and also do memory statistics to find all the
 374 *	[BEEP] leaks.
 375 *
 376 */
 377
 378/**
 379 *	__alloc_skb	-	allocate a network buffer
 380 *	@size: size to allocate
 381 *	@gfp_mask: allocation mask
 382 *	@flags: If SKB_ALLOC_FCLONE is set, allocate from fclone cache
 383 *		instead of head cache and allocate a cloned (child) skb.
 384 *		If SKB_ALLOC_RX is set, __GFP_MEMALLOC will be used for
 385 *		allocations in case the data is required for writeback
 386 *	@node: numa node to allocate memory on
 387 *
 388 *	Allocate a new &sk_buff. The returned buffer has no headroom and a
 389 *	tail room of at least size bytes. The object has a reference count
 390 *	of one. The return is the buffer. On a failure the return is %NULL.
 391 *
 392 *	Buffers may only be allocated from interrupts using a @gfp_mask of
 393 *	%GFP_ATOMIC.
 394 */
 395struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
 396			    int flags, int node)
 397{
 398	struct kmem_cache *cache;
 399	struct sk_buff *skb;
 400	u8 *data;
 401	bool pfmemalloc;
 402
 403	cache = (flags & SKB_ALLOC_FCLONE)
 404		? skbuff_fclone_cache : skbuff_head_cache;
 405
 406	if (sk_memalloc_socks() && (flags & SKB_ALLOC_RX))
 407		gfp_mask |= __GFP_MEMALLOC;
 408
 409	/* Get the HEAD */
 410	if ((flags & (SKB_ALLOC_FCLONE | SKB_ALLOC_NAPI)) == SKB_ALLOC_NAPI &&
 411	    likely(node == NUMA_NO_NODE || node == numa_mem_id()))
 412		skb = napi_skb_cache_get();
 413	else
 414		skb = kmem_cache_alloc_node(cache, gfp_mask & ~GFP_DMA, node);
 415	if (unlikely(!skb))
 416		return NULL;
 417	prefetchw(skb);
 418
 419	/* We do our best to align skb_shared_info on a separate cache
 420	 * line. It usually works because kmalloc(X > SMP_CACHE_BYTES) gives
 421	 * aligned memory blocks, unless SLUB/SLAB debug is enabled.
 422	 * Both skb->head and skb_shared_info are cache line aligned.
 423	 */
 424	size = SKB_DATA_ALIGN(size);
 425	size += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
 426	data = kmalloc_reserve(size, gfp_mask, node, &pfmemalloc);
 427	if (unlikely(!data))
 428		goto nodata;
 429	/* kmalloc(size) might give us more room than requested.
 430	 * Put skb_shared_info exactly at the end of allocated zone,
 431	 * to allow max possible filling before reallocation.
 432	 */
 433	size = SKB_WITH_OVERHEAD(ksize(data));
 434	prefetchw(data + size);
 435
 436	/*
 437	 * Only clear those fields we need to clear, not those that we will
 438	 * actually initialise below. Hence, don't put any more fields after
 439	 * the tail pointer in struct sk_buff!
 440	 */
 441	memset(skb, 0, offsetof(struct sk_buff, tail));
 442	__build_skb_around(skb, data, 0);
 443	skb->pfmemalloc = pfmemalloc;
 444
 445	if (flags & SKB_ALLOC_FCLONE) {
 446		struct sk_buff_fclones *fclones;
 447
 448		fclones = container_of(skb, struct sk_buff_fclones, skb1);
 449
 450		skb->fclone = SKB_FCLONE_ORIG;
 451		refcount_set(&fclones->fclone_ref, 1);
 452
 453		fclones->skb2.fclone = SKB_FCLONE_CLONE;
 
 
 
 
 
 
 
 454	}
 455
 456	return skb;
 457
 458nodata:
 459	kmem_cache_free(cache, skb);
 460	return NULL;
 461}
 462EXPORT_SYMBOL(__alloc_skb);
 463
 464/**
 465 *	__netdev_alloc_skb - allocate an skbuff for rx on a specific device
 466 *	@dev: network device to receive on
 467 *	@len: length to allocate
 468 *	@gfp_mask: get_free_pages mask, passed to alloc_skb
 469 *
 470 *	Allocate a new &sk_buff and assign it a usage count of one. The
 471 *	buffer has NET_SKB_PAD headroom built in. Users should allocate
 472 *	the headroom they think they need without accounting for the
 473 *	built in space. The built in space is used for optimisations.
 474 *
 475 *	%NULL is returned if there is no free memory.
 476 */
 477struct sk_buff *__netdev_alloc_skb(struct net_device *dev, unsigned int len,
 478				   gfp_t gfp_mask)
 479{
 480	struct page_frag_cache *nc;
 481	struct sk_buff *skb;
 482	bool pfmemalloc;
 483	void *data;
 484
 485	len += NET_SKB_PAD;
 486
 487	/* If requested length is either too small or too big,
 488	 * we use kmalloc() for skb->head allocation.
 489	 */
 490	if (len <= SKB_WITH_OVERHEAD(1024) ||
 491	    len > SKB_WITH_OVERHEAD(PAGE_SIZE) ||
 492	    (gfp_mask & (__GFP_DIRECT_RECLAIM | GFP_DMA))) {
 493		skb = __alloc_skb(len, gfp_mask, SKB_ALLOC_RX, NUMA_NO_NODE);
 494		if (!skb)
 495			goto skb_fail;
 496		goto skb_success;
 497	}
 498
 499	len += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
 500	len = SKB_DATA_ALIGN(len);
 501
 502	if (sk_memalloc_socks())
 503		gfp_mask |= __GFP_MEMALLOC;
 504
 505	if (in_irq() || irqs_disabled()) {
 506		nc = this_cpu_ptr(&netdev_alloc_cache);
 507		data = page_frag_alloc(nc, len, gfp_mask);
 508		pfmemalloc = nc->pfmemalloc;
 509	} else {
 510		local_bh_disable();
 511		nc = this_cpu_ptr(&napi_alloc_cache.page);
 512		data = page_frag_alloc(nc, len, gfp_mask);
 513		pfmemalloc = nc->pfmemalloc;
 514		local_bh_enable();
 515	}
 516
 517	if (unlikely(!data))
 518		return NULL;
 519
 520	skb = __build_skb(data, len);
 521	if (unlikely(!skb)) {
 522		skb_free_frag(data);
 523		return NULL;
 524	}
 525
 526	if (pfmemalloc)
 527		skb->pfmemalloc = 1;
 528	skb->head_frag = 1;
 529
 530skb_success:
 531	skb_reserve(skb, NET_SKB_PAD);
 532	skb->dev = dev;
 533
 534skb_fail:
 535	return skb;
 536}
 537EXPORT_SYMBOL(__netdev_alloc_skb);
 538
 539/**
 540 *	__napi_alloc_skb - allocate skbuff for rx in a specific NAPI instance
 541 *	@napi: napi instance this buffer was allocated for
 542 *	@len: length to allocate
 543 *	@gfp_mask: get_free_pages mask, passed to alloc_skb and alloc_pages
 544 *
 545 *	Allocate a new sk_buff for use in NAPI receive.  This buffer will
 546 *	attempt to allocate the head from a special reserved region used
 547 *	only for NAPI Rx allocation.  By doing this we can save several
 548 *	CPU cycles by avoiding having to disable and re-enable IRQs.
 549 *
 550 *	%NULL is returned if there is no free memory.
 551 */
 552struct sk_buff *__napi_alloc_skb(struct napi_struct *napi, unsigned int len,
 553				 gfp_t gfp_mask)
 554{
 555	struct napi_alloc_cache *nc;
 556	struct sk_buff *skb;
 557	void *data;
 558
 559	len += NET_SKB_PAD + NET_IP_ALIGN;
 560
 561	/* If requested length is either too small or too big,
 562	 * we use kmalloc() for skb->head allocation.
 563	 */
 564	if (len <= SKB_WITH_OVERHEAD(1024) ||
 565	    len > SKB_WITH_OVERHEAD(PAGE_SIZE) ||
 566	    (gfp_mask & (__GFP_DIRECT_RECLAIM | GFP_DMA))) {
 567		skb = __alloc_skb(len, gfp_mask, SKB_ALLOC_RX | SKB_ALLOC_NAPI,
 568				  NUMA_NO_NODE);
 569		if (!skb)
 570			goto skb_fail;
 571		goto skb_success;
 572	}
 573
 574	nc = this_cpu_ptr(&napi_alloc_cache);
 575	len += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
 576	len = SKB_DATA_ALIGN(len);
 577
 578	if (sk_memalloc_socks())
 579		gfp_mask |= __GFP_MEMALLOC;
 580
 581	data = page_frag_alloc(&nc->page, len, gfp_mask);
 582	if (unlikely(!data))
 583		return NULL;
 584
 585	skb = __napi_build_skb(data, len);
 586	if (unlikely(!skb)) {
 587		skb_free_frag(data);
 588		return NULL;
 589	}
 590
 591	if (nc->page.pfmemalloc)
 592		skb->pfmemalloc = 1;
 593	skb->head_frag = 1;
 594
 595skb_success:
 596	skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN);
 597	skb->dev = napi->dev;
 598
 599skb_fail:
 600	return skb;
 601}
 602EXPORT_SYMBOL(__napi_alloc_skb);
 603
 604void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page, int off,
 605		     int size, unsigned int truesize)
 606{
 607	skb_fill_page_desc(skb, i, page, off, size);
 608	skb->len += size;
 609	skb->data_len += size;
 610	skb->truesize += truesize;
 611}
 612EXPORT_SYMBOL(skb_add_rx_frag);
 613
 614void skb_coalesce_rx_frag(struct sk_buff *skb, int i, int size,
 615			  unsigned int truesize)
 616{
 617	skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
 618
 619	skb_frag_size_add(frag, size);
 620	skb->len += size;
 621	skb->data_len += size;
 622	skb->truesize += truesize;
 623}
 624EXPORT_SYMBOL(skb_coalesce_rx_frag);
 625
 626static void skb_drop_list(struct sk_buff **listp)
 627{
 628	kfree_skb_list(*listp);
 629	*listp = NULL;
 630}
 631
 632static inline void skb_drop_fraglist(struct sk_buff *skb)
 633{
 634	skb_drop_list(&skb_shinfo(skb)->frag_list);
 635}
 636
 637static void skb_clone_fraglist(struct sk_buff *skb)
 638{
 639	struct sk_buff *list;
 640
 641	skb_walk_frags(skb, list)
 642		skb_get(list);
 643}
 644
 645static void skb_free_head(struct sk_buff *skb)
 646{
 647	unsigned char *head = skb->head;
 648
 649	if (skb->head_frag) {
 650		if (skb_pp_recycle(skb, head))
 651			return;
 652		skb_free_frag(head);
 653	} else {
 654		kfree(head);
 655	}
 656}
 657
 658static void skb_release_data(struct sk_buff *skb)
 659{
 660	struct skb_shared_info *shinfo = skb_shinfo(skb);
 661	int i;
 662
 663	if (skb->cloned &&
 664	    atomic_sub_return(skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1,
 665			      &shinfo->dataref))
 666		goto exit;
 667
 668	skb_zcopy_clear(skb, true);
 669
 670	for (i = 0; i < shinfo->nr_frags; i++)
 671		__skb_frag_unref(&shinfo->frags[i], skb->pp_recycle);
 672
 673	if (shinfo->frag_list)
 674		kfree_skb_list(shinfo->frag_list);
 675
 
 676	skb_free_head(skb);
 677exit:
 678	/* When we clone an SKB we copy the reycling bit. The pp_recycle
 679	 * bit is only set on the head though, so in order to avoid races
 680	 * while trying to recycle fragments on __skb_frag_unref() we need
 681	 * to make one SKB responsible for triggering the recycle path.
 682	 * So disable the recycling bit if an SKB is cloned and we have
 683	 * additional references to to the fragmented part of the SKB.
 684	 * Eventually the last SKB will have the recycling bit set and it's
 685	 * dataref set to 0, which will trigger the recycling
 686	 */
 687	skb->pp_recycle = 0;
 688}
 689
 690/*
 691 *	Free an skbuff by memory without cleaning the state.
 692 */
 693static void kfree_skbmem(struct sk_buff *skb)
 694{
 695	struct sk_buff_fclones *fclones;
 696
 697	switch (skb->fclone) {
 698	case SKB_FCLONE_UNAVAILABLE:
 699		kmem_cache_free(skbuff_head_cache, skb);
 700		return;
 701
 702	case SKB_FCLONE_ORIG:
 703		fclones = container_of(skb, struct sk_buff_fclones, skb1);
 704
 705		/* We usually free the clone (TX completion) before original skb
 706		 * This test would have no chance to be true for the clone,
 707		 * while here, branch prediction will be good.
 708		 */
 709		if (refcount_read(&fclones->fclone_ref) == 1)
 710			goto fastpath;
 711		break;
 712
 713	default: /* SKB_FCLONE_CLONE */
 714		fclones = container_of(skb, struct sk_buff_fclones, skb2);
 715		break;
 716	}
 717	if (!refcount_dec_and_test(&fclones->fclone_ref))
 718		return;
 719fastpath:
 720	kmem_cache_free(skbuff_fclone_cache, fclones);
 721}
 722
 723void skb_release_head_state(struct sk_buff *skb)
 724{
 725	skb_dst_drop(skb);
 726	if (skb->destructor) {
 727		WARN_ON(in_irq());
 728		skb->destructor(skb);
 729	}
 730#if IS_ENABLED(CONFIG_NF_CONNTRACK)
 731	nf_conntrack_put(skb_nfct(skb));
 732#endif
 733	skb_ext_put(skb);
 734}
 735
 736/* Free everything but the sk_buff shell. */
 737static void skb_release_all(struct sk_buff *skb)
 738{
 739	skb_release_head_state(skb);
 740	if (likely(skb->head))
 741		skb_release_data(skb);
 742}
 743
 744/**
 745 *	__kfree_skb - private function
 746 *	@skb: buffer
 747 *
 748 *	Free an sk_buff. Release anything attached to the buffer.
 749 *	Clean the state. This is an internal helper function. Users should
 750 *	always call kfree_skb
 751 */
 752
 753void __kfree_skb(struct sk_buff *skb)
 754{
 755	skb_release_all(skb);
 756	kfree_skbmem(skb);
 757}
 758EXPORT_SYMBOL(__kfree_skb);
 759
 760/**
 761 *	kfree_skb - free an sk_buff
 762 *	@skb: buffer to free
 763 *
 764 *	Drop a reference to the buffer and free it if the usage count has
 765 *	hit zero.
 766 */
 767void kfree_skb(struct sk_buff *skb)
 768{
 769	if (!skb_unref(skb))
 770		return;
 771
 772	trace_kfree_skb(skb, __builtin_return_address(0));
 773	__kfree_skb(skb);
 774}
 775EXPORT_SYMBOL(kfree_skb);
 776
 777void kfree_skb_list(struct sk_buff *segs)
 778{
 779	while (segs) {
 780		struct sk_buff *next = segs->next;
 781
 782		kfree_skb(segs);
 783		segs = next;
 784	}
 785}
 786EXPORT_SYMBOL(kfree_skb_list);
 787
 788/* Dump skb information and contents.
 789 *
 790 * Must only be called from net_ratelimit()-ed paths.
 791 *
 792 * Dumps whole packets if full_pkt, only headers otherwise.
 793 */
 794void skb_dump(const char *level, const struct sk_buff *skb, bool full_pkt)
 795{
 
 796	struct skb_shared_info *sh = skb_shinfo(skb);
 797	struct net_device *dev = skb->dev;
 798	struct sock *sk = skb->sk;
 799	struct sk_buff *list_skb;
 800	bool has_mac, has_trans;
 801	int headroom, tailroom;
 802	int i, len, seg_len;
 803
 804	if (full_pkt)
 
 
 
 805		len = skb->len;
 806	else
 807		len = min_t(int, skb->len, MAX_HEADER + 128);
 808
 809	headroom = skb_headroom(skb);
 810	tailroom = skb_tailroom(skb);
 811
 812	has_mac = skb_mac_header_was_set(skb);
 813	has_trans = skb_transport_header_was_set(skb);
 814
 815	printk("%sskb len=%u headroom=%u headlen=%u tailroom=%u\n"
 816	       "mac=(%d,%d) net=(%d,%d) trans=%d\n"
 817	       "shinfo(txflags=%u nr_frags=%u gso(size=%hu type=%u segs=%hu))\n"
 818	       "csum(0x%x ip_summed=%u complete_sw=%u valid=%u level=%u)\n"
 819	       "hash(0x%x sw=%u l4=%u) proto=0x%04x pkttype=%u iif=%d\n",
 820	       level, skb->len, headroom, skb_headlen(skb), tailroom,
 821	       has_mac ? skb->mac_header : -1,
 822	       has_mac ? skb_mac_header_len(skb) : -1,
 823	       skb->network_header,
 824	       has_trans ? skb_network_header_len(skb) : -1,
 825	       has_trans ? skb->transport_header : -1,
 826	       sh->tx_flags, sh->nr_frags,
 827	       sh->gso_size, sh->gso_type, sh->gso_segs,
 828	       skb->csum, skb->ip_summed, skb->csum_complete_sw,
 829	       skb->csum_valid, skb->csum_level,
 830	       skb->hash, skb->sw_hash, skb->l4_hash,
 831	       ntohs(skb->protocol), skb->pkt_type, skb->skb_iif);
 832
 833	if (dev)
 834		printk("%sdev name=%s feat=0x%pNF\n",
 835		       level, dev->name, &dev->features);
 836	if (sk)
 837		printk("%ssk family=%hu type=%u proto=%u\n",
 838		       level, sk->sk_family, sk->sk_type, sk->sk_protocol);
 839
 840	if (full_pkt && headroom)
 841		print_hex_dump(level, "skb headroom: ", DUMP_PREFIX_OFFSET,
 842			       16, 1, skb->head, headroom, false);
 843
 844	seg_len = min_t(int, skb_headlen(skb), len);
 845	if (seg_len)
 846		print_hex_dump(level, "skb linear:   ", DUMP_PREFIX_OFFSET,
 847			       16, 1, skb->data, seg_len, false);
 848	len -= seg_len;
 849
 850	if (full_pkt && tailroom)
 851		print_hex_dump(level, "skb tailroom: ", DUMP_PREFIX_OFFSET,
 852			       16, 1, skb_tail_pointer(skb), tailroom, false);
 853
 854	for (i = 0; len && i < skb_shinfo(skb)->nr_frags; i++) {
 855		skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
 856		u32 p_off, p_len, copied;
 857		struct page *p;
 858		u8 *vaddr;
 859
 860		skb_frag_foreach_page(frag, skb_frag_off(frag),
 861				      skb_frag_size(frag), p, p_off, p_len,
 862				      copied) {
 863			seg_len = min_t(int, p_len, len);
 864			vaddr = kmap_atomic(p);
 865			print_hex_dump(level, "skb frag:     ",
 866				       DUMP_PREFIX_OFFSET,
 867				       16, 1, vaddr + p_off, seg_len, false);
 868			kunmap_atomic(vaddr);
 869			len -= seg_len;
 870			if (!len)
 871				break;
 872		}
 873	}
 874
 875	if (full_pkt && skb_has_frag_list(skb)) {
 876		printk("skb fraglist:\n");
 877		skb_walk_frags(skb, list_skb)
 878			skb_dump(level, list_skb, true);
 879	}
 880}
 881EXPORT_SYMBOL(skb_dump);
 882
 883/**
 884 *	skb_tx_error - report an sk_buff xmit error
 885 *	@skb: buffer that triggered an error
 886 *
 887 *	Report xmit error if a device callback is tracking this skb.
 888 *	skb must be freed afterwards.
 889 */
 890void skb_tx_error(struct sk_buff *skb)
 891{
 892	skb_zcopy_clear(skb, true);
 893}
 894EXPORT_SYMBOL(skb_tx_error);
 895
 896#ifdef CONFIG_TRACEPOINTS
 897/**
 898 *	consume_skb - free an skbuff
 899 *	@skb: buffer to free
 900 *
 901 *	Drop a ref to the buffer and free it if the usage count has hit zero
 902 *	Functions identically to kfree_skb, but kfree_skb assumes that the frame
 903 *	is being dropped after a failure and notes that
 904 */
 905void consume_skb(struct sk_buff *skb)
 906{
 907	if (!skb_unref(skb))
 908		return;
 909
 910	trace_consume_skb(skb);
 911	__kfree_skb(skb);
 912}
 913EXPORT_SYMBOL(consume_skb);
 914#endif
 915
 916/**
 917 *	__consume_stateless_skb - free an skbuff, assuming it is stateless
 918 *	@skb: buffer to free
 919 *
 920 *	Alike consume_skb(), but this variant assumes that this is the last
 921 *	skb reference and all the head states have been already dropped
 922 */
 923void __consume_stateless_skb(struct sk_buff *skb)
 924{
 925	trace_consume_skb(skb);
 926	skb_release_data(skb);
 927	kfree_skbmem(skb);
 928}
 929
 930static void napi_skb_cache_put(struct sk_buff *skb)
 931{
 932	struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
 933	u32 i;
 934
 935	kasan_poison_object_data(skbuff_head_cache, skb);
 936	nc->skb_cache[nc->skb_count++] = skb;
 937
 938	if (unlikely(nc->skb_count == NAPI_SKB_CACHE_SIZE)) {
 939		for (i = NAPI_SKB_CACHE_HALF; i < NAPI_SKB_CACHE_SIZE; i++)
 940			kasan_unpoison_object_data(skbuff_head_cache,
 941						   nc->skb_cache[i]);
 942
 943		kmem_cache_free_bulk(skbuff_head_cache, NAPI_SKB_CACHE_HALF,
 944				     nc->skb_cache + NAPI_SKB_CACHE_HALF);
 945		nc->skb_count = NAPI_SKB_CACHE_HALF;
 946	}
 947}
 948
 949void __kfree_skb_defer(struct sk_buff *skb)
 950{
 
 
 
 951	skb_release_all(skb);
 952	napi_skb_cache_put(skb);
 953}
 954
 955void napi_skb_free_stolen_head(struct sk_buff *skb)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 956{
 957	nf_reset_ct(skb);
 958	skb_dst_drop(skb);
 959	skb_ext_put(skb);
 960	napi_skb_cache_put(skb);
 961}
 962
 963void napi_consume_skb(struct sk_buff *skb, int budget)
 964{
 
 
 
 965	/* Zero budget indicate non-NAPI context called us, like netpoll */
 966	if (unlikely(!budget)) {
 967		dev_consume_skb_any(skb);
 968		return;
 969	}
 970
 971	lockdep_assert_in_softirq();
 972
 973	if (!skb_unref(skb))
 974		return;
 975
 976	/* if reaching here SKB is ready to free */
 977	trace_consume_skb(skb);
 978
 979	/* if SKB is a clone, don't handle this case */
 980	if (skb->fclone != SKB_FCLONE_UNAVAILABLE) {
 981		__kfree_skb(skb);
 982		return;
 983	}
 984
 985	skb_release_all(skb);
 986	napi_skb_cache_put(skb);
 987}
 988EXPORT_SYMBOL(napi_consume_skb);
 989
 990/* Make sure a field is enclosed inside headers_start/headers_end section */
 991#define CHECK_SKB_FIELD(field) \
 992	BUILD_BUG_ON(offsetof(struct sk_buff, field) <		\
 993		     offsetof(struct sk_buff, headers_start));	\
 994	BUILD_BUG_ON(offsetof(struct sk_buff, field) >		\
 995		     offsetof(struct sk_buff, headers_end));	\
 996
 997static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
 998{
 999	new->tstamp		= old->tstamp;
1000	/* We do not copy old->sk */
1001	new->dev		= old->dev;
1002	memcpy(new->cb, old->cb, sizeof(old->cb));
1003	skb_dst_copy(new, old);
1004	__skb_ext_copy(new, old);
1005	__nf_copy(new, old, false);
1006
1007	/* Note : this field could be in headers_start/headers_end section
1008	 * It is not yet because we do not want to have a 16 bit hole
1009	 */
1010	new->queue_mapping = old->queue_mapping;
1011
1012	memcpy(&new->headers_start, &old->headers_start,
1013	       offsetof(struct sk_buff, headers_end) -
1014	       offsetof(struct sk_buff, headers_start));
1015	CHECK_SKB_FIELD(protocol);
1016	CHECK_SKB_FIELD(csum);
1017	CHECK_SKB_FIELD(hash);
1018	CHECK_SKB_FIELD(priority);
1019	CHECK_SKB_FIELD(skb_iif);
1020	CHECK_SKB_FIELD(vlan_proto);
1021	CHECK_SKB_FIELD(vlan_tci);
1022	CHECK_SKB_FIELD(transport_header);
1023	CHECK_SKB_FIELD(network_header);
1024	CHECK_SKB_FIELD(mac_header);
1025	CHECK_SKB_FIELD(inner_protocol);
1026	CHECK_SKB_FIELD(inner_transport_header);
1027	CHECK_SKB_FIELD(inner_network_header);
1028	CHECK_SKB_FIELD(inner_mac_header);
1029	CHECK_SKB_FIELD(mark);
1030#ifdef CONFIG_NETWORK_SECMARK
1031	CHECK_SKB_FIELD(secmark);
1032#endif
1033#ifdef CONFIG_NET_RX_BUSY_POLL
1034	CHECK_SKB_FIELD(napi_id);
1035#endif
1036#ifdef CONFIG_XPS
1037	CHECK_SKB_FIELD(sender_cpu);
1038#endif
1039#ifdef CONFIG_NET_SCHED
1040	CHECK_SKB_FIELD(tc_index);
1041#endif
1042
1043}
1044
1045/*
1046 * You should not add any new code to this function.  Add it to
1047 * __copy_skb_header above instead.
1048 */
1049static struct sk_buff *__skb_clone(struct sk_buff *n, struct sk_buff *skb)
1050{
1051#define C(x) n->x = skb->x
1052
1053	n->next = n->prev = NULL;
1054	n->sk = NULL;
1055	__copy_skb_header(n, skb);
1056
1057	C(len);
1058	C(data_len);
1059	C(mac_len);
1060	n->hdr_len = skb->nohdr ? skb_headroom(skb) : skb->hdr_len;
1061	n->cloned = 1;
1062	n->nohdr = 0;
1063	n->peeked = 0;
1064	C(pfmemalloc);
1065	C(pp_recycle);
1066	n->destructor = NULL;
1067	C(tail);
1068	C(end);
1069	C(head);
1070	C(head_frag);
1071	C(data);
1072	C(truesize);
1073	refcount_set(&n->users, 1);
1074
1075	atomic_inc(&(skb_shinfo(skb)->dataref));
1076	skb->cloned = 1;
1077
1078	return n;
1079#undef C
1080}
1081
1082/**
1083 * alloc_skb_for_msg() - allocate sk_buff to wrap frag list forming a msg
1084 * @first: first sk_buff of the msg
1085 */
1086struct sk_buff *alloc_skb_for_msg(struct sk_buff *first)
1087{
1088	struct sk_buff *n;
1089
1090	n = alloc_skb(0, GFP_ATOMIC);
1091	if (!n)
1092		return NULL;
1093
1094	n->len = first->len;
1095	n->data_len = first->len;
1096	n->truesize = first->truesize;
1097
1098	skb_shinfo(n)->frag_list = first;
1099
1100	__copy_skb_header(n, first);
1101	n->destructor = NULL;
1102
1103	return n;
1104}
1105EXPORT_SYMBOL_GPL(alloc_skb_for_msg);
1106
1107/**
1108 *	skb_morph	-	morph one skb into another
1109 *	@dst: the skb to receive the contents
1110 *	@src: the skb to supply the contents
1111 *
1112 *	This is identical to skb_clone except that the target skb is
1113 *	supplied by the user.
1114 *
1115 *	The target skb is returned upon exit.
1116 */
1117struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src)
1118{
1119	skb_release_all(dst);
1120	return __skb_clone(dst, src);
1121}
1122EXPORT_SYMBOL_GPL(skb_morph);
1123
1124int mm_account_pinned_pages(struct mmpin *mmp, size_t size)
1125{
1126	unsigned long max_pg, num_pg, new_pg, old_pg;
1127	struct user_struct *user;
1128
1129	if (capable(CAP_IPC_LOCK) || !size)
1130		return 0;
1131
1132	num_pg = (size >> PAGE_SHIFT) + 2;	/* worst case */
1133	max_pg = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
1134	user = mmp->user ? : current_user();
1135
1136	do {
1137		old_pg = atomic_long_read(&user->locked_vm);
1138		new_pg = old_pg + num_pg;
1139		if (new_pg > max_pg)
1140			return -ENOBUFS;
1141	} while (atomic_long_cmpxchg(&user->locked_vm, old_pg, new_pg) !=
1142		 old_pg);
1143
1144	if (!mmp->user) {
1145		mmp->user = get_uid(user);
1146		mmp->num_pg = num_pg;
1147	} else {
1148		mmp->num_pg += num_pg;
1149	}
1150
1151	return 0;
1152}
1153EXPORT_SYMBOL_GPL(mm_account_pinned_pages);
1154
1155void mm_unaccount_pinned_pages(struct mmpin *mmp)
1156{
1157	if (mmp->user) {
1158		atomic_long_sub(mmp->num_pg, &mmp->user->locked_vm);
1159		free_uid(mmp->user);
1160	}
1161}
1162EXPORT_SYMBOL_GPL(mm_unaccount_pinned_pages);
1163
1164struct ubuf_info *msg_zerocopy_alloc(struct sock *sk, size_t size)
1165{
1166	struct ubuf_info *uarg;
1167	struct sk_buff *skb;
1168
1169	WARN_ON_ONCE(!in_task());
1170
1171	skb = sock_omalloc(sk, 0, GFP_KERNEL);
1172	if (!skb)
1173		return NULL;
1174
1175	BUILD_BUG_ON(sizeof(*uarg) > sizeof(skb->cb));
1176	uarg = (void *)skb->cb;
1177	uarg->mmp.user = NULL;
1178
1179	if (mm_account_pinned_pages(&uarg->mmp, size)) {
1180		kfree_skb(skb);
1181		return NULL;
1182	}
1183
1184	uarg->callback = msg_zerocopy_callback;
1185	uarg->id = ((u32)atomic_inc_return(&sk->sk_zckey)) - 1;
1186	uarg->len = 1;
1187	uarg->bytelen = size;
1188	uarg->zerocopy = 1;
1189	uarg->flags = SKBFL_ZEROCOPY_FRAG;
1190	refcount_set(&uarg->refcnt, 1);
1191	sock_hold(sk);
1192
1193	return uarg;
1194}
1195EXPORT_SYMBOL_GPL(msg_zerocopy_alloc);
1196
1197static inline struct sk_buff *skb_from_uarg(struct ubuf_info *uarg)
1198{
1199	return container_of((void *)uarg, struct sk_buff, cb);
1200}
1201
1202struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
1203				       struct ubuf_info *uarg)
1204{
1205	if (uarg) {
1206		const u32 byte_limit = 1 << 19;		/* limit to a few TSO */
1207		u32 bytelen, next;
1208
1209		/* realloc only when socket is locked (TCP, UDP cork),
1210		 * so uarg->len and sk_zckey access is serialized
1211		 */
1212		if (!sock_owned_by_user(sk)) {
1213			WARN_ON_ONCE(1);
1214			return NULL;
1215		}
1216
1217		bytelen = uarg->bytelen + size;
1218		if (uarg->len == USHRT_MAX - 1 || bytelen > byte_limit) {
1219			/* TCP can create new skb to attach new uarg */
1220			if (sk->sk_type == SOCK_STREAM)
1221				goto new_alloc;
1222			return NULL;
1223		}
1224
1225		next = (u32)atomic_read(&sk->sk_zckey);
1226		if ((u32)(uarg->id + uarg->len) == next) {
1227			if (mm_account_pinned_pages(&uarg->mmp, size))
1228				return NULL;
1229			uarg->len++;
1230			uarg->bytelen = bytelen;
1231			atomic_set(&sk->sk_zckey, ++next);
1232
1233			/* no extra ref when appending to datagram (MSG_MORE) */
1234			if (sk->sk_type == SOCK_STREAM)
1235				net_zcopy_get(uarg);
1236
1237			return uarg;
1238		}
1239	}
1240
1241new_alloc:
1242	return msg_zerocopy_alloc(sk, size);
1243}
1244EXPORT_SYMBOL_GPL(msg_zerocopy_realloc);
1245
1246static bool skb_zerocopy_notify_extend(struct sk_buff *skb, u32 lo, u16 len)
1247{
1248	struct sock_exterr_skb *serr = SKB_EXT_ERR(skb);
1249	u32 old_lo, old_hi;
1250	u64 sum_len;
1251
1252	old_lo = serr->ee.ee_info;
1253	old_hi = serr->ee.ee_data;
1254	sum_len = old_hi - old_lo + 1ULL + len;
1255
1256	if (sum_len >= (1ULL << 32))
1257		return false;
1258
1259	if (lo != old_hi + 1)
1260		return false;
1261
1262	serr->ee.ee_data += len;
1263	return true;
1264}
1265
1266static void __msg_zerocopy_callback(struct ubuf_info *uarg)
1267{
1268	struct sk_buff *tail, *skb = skb_from_uarg(uarg);
1269	struct sock_exterr_skb *serr;
1270	struct sock *sk = skb->sk;
1271	struct sk_buff_head *q;
1272	unsigned long flags;
1273	bool is_zerocopy;
1274	u32 lo, hi;
1275	u16 len;
1276
1277	mm_unaccount_pinned_pages(&uarg->mmp);
1278
1279	/* if !len, there was only 1 call, and it was aborted
1280	 * so do not queue a completion notification
1281	 */
1282	if (!uarg->len || sock_flag(sk, SOCK_DEAD))
1283		goto release;
1284
1285	len = uarg->len;
1286	lo = uarg->id;
1287	hi = uarg->id + len - 1;
1288	is_zerocopy = uarg->zerocopy;
1289
1290	serr = SKB_EXT_ERR(skb);
1291	memset(serr, 0, sizeof(*serr));
1292	serr->ee.ee_errno = 0;
1293	serr->ee.ee_origin = SO_EE_ORIGIN_ZEROCOPY;
1294	serr->ee.ee_data = hi;
1295	serr->ee.ee_info = lo;
1296	if (!is_zerocopy)
1297		serr->ee.ee_code |= SO_EE_CODE_ZEROCOPY_COPIED;
1298
1299	q = &sk->sk_error_queue;
1300	spin_lock_irqsave(&q->lock, flags);
1301	tail = skb_peek_tail(q);
1302	if (!tail || SKB_EXT_ERR(tail)->ee.ee_origin != SO_EE_ORIGIN_ZEROCOPY ||
1303	    !skb_zerocopy_notify_extend(tail, lo, len)) {
1304		__skb_queue_tail(q, skb);
1305		skb = NULL;
1306	}
1307	spin_unlock_irqrestore(&q->lock, flags);
1308
1309	sk_error_report(sk);
1310
1311release:
1312	consume_skb(skb);
1313	sock_put(sk);
1314}
 
1315
1316void msg_zerocopy_callback(struct sk_buff *skb, struct ubuf_info *uarg,
1317			   bool success)
1318{
1319	uarg->zerocopy = uarg->zerocopy & success;
1320
1321	if (refcount_dec_and_test(&uarg->refcnt))
1322		__msg_zerocopy_callback(uarg);
 
 
1323}
1324EXPORT_SYMBOL_GPL(msg_zerocopy_callback);
1325
1326void msg_zerocopy_put_abort(struct ubuf_info *uarg, bool have_uref)
1327{
1328	struct sock *sk = skb_from_uarg(uarg)->sk;
 
1329
1330	atomic_dec(&sk->sk_zckey);
1331	uarg->len--;
1332
1333	if (have_uref)
1334		msg_zerocopy_callback(NULL, uarg, true);
 
1335}
1336EXPORT_SYMBOL_GPL(msg_zerocopy_put_abort);
1337
1338int skb_zerocopy_iter_dgram(struct sk_buff *skb, struct msghdr *msg, int len)
1339{
1340	return __zerocopy_sg_from_iter(skb->sk, skb, &msg->msg_iter, len);
1341}
1342EXPORT_SYMBOL_GPL(skb_zerocopy_iter_dgram);
1343
1344int skb_zerocopy_iter_stream(struct sock *sk, struct sk_buff *skb,
1345			     struct msghdr *msg, int len,
1346			     struct ubuf_info *uarg)
1347{
1348	struct ubuf_info *orig_uarg = skb_zcopy(skb);
1349	struct iov_iter orig_iter = msg->msg_iter;
1350	int err, orig_len = skb->len;
1351
1352	/* An skb can only point to one uarg. This edge case happens when
1353	 * TCP appends to an skb, but zerocopy_realloc triggered a new alloc.
1354	 */
1355	if (orig_uarg && uarg != orig_uarg)
1356		return -EEXIST;
1357
1358	err = __zerocopy_sg_from_iter(sk, skb, &msg->msg_iter, len);
1359	if (err == -EFAULT || (err == -EMSGSIZE && skb->len == orig_len)) {
1360		struct sock *save_sk = skb->sk;
1361
1362		/* Streams do not free skb on error. Reset to prev state. */
1363		msg->msg_iter = orig_iter;
1364		skb->sk = sk;
1365		___pskb_trim(skb, orig_len);
1366		skb->sk = save_sk;
1367		return err;
1368	}
1369
1370	skb_zcopy_set(skb, uarg, NULL);
1371	return skb->len - orig_len;
1372}
1373EXPORT_SYMBOL_GPL(skb_zerocopy_iter_stream);
1374
1375static int skb_zerocopy_clone(struct sk_buff *nskb, struct sk_buff *orig,
1376			      gfp_t gfp_mask)
1377{
1378	if (skb_zcopy(orig)) {
1379		if (skb_zcopy(nskb)) {
1380			/* !gfp_mask callers are verified to !skb_zcopy(nskb) */
1381			if (!gfp_mask) {
1382				WARN_ON_ONCE(1);
1383				return -ENOMEM;
1384			}
1385			if (skb_uarg(nskb) == skb_uarg(orig))
1386				return 0;
1387			if (skb_copy_ubufs(nskb, GFP_ATOMIC))
1388				return -EIO;
1389		}
1390		skb_zcopy_set(nskb, skb_uarg(orig), NULL);
1391	}
1392	return 0;
1393}
1394
1395/**
1396 *	skb_copy_ubufs	-	copy userspace skb frags buffers to kernel
1397 *	@skb: the skb to modify
1398 *	@gfp_mask: allocation priority
1399 *
1400 *	This must be called on skb with SKBFL_ZEROCOPY_ENABLE.
1401 *	It will copy all frags into kernel and drop the reference
1402 *	to userspace pages.
1403 *
1404 *	If this function is called from an interrupt gfp_mask() must be
1405 *	%GFP_ATOMIC.
1406 *
1407 *	Returns 0 on success or a negative error code on failure
1408 *	to allocate kernel memory to copy to.
1409 */
1410int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask)
1411{
1412	int num_frags = skb_shinfo(skb)->nr_frags;
1413	struct page *page, *head = NULL;
1414	int i, new_frags;
1415	u32 d_off;
1416
1417	if (skb_shared(skb) || skb_unclone(skb, gfp_mask))
1418		return -EINVAL;
1419
1420	if (!num_frags)
1421		goto release;
1422
1423	new_frags = (__skb_pagelen(skb) + PAGE_SIZE - 1) >> PAGE_SHIFT;
1424	for (i = 0; i < new_frags; i++) {
1425		page = alloc_page(gfp_mask);
1426		if (!page) {
1427			while (head) {
1428				struct page *next = (struct page *)page_private(head);
1429				put_page(head);
1430				head = next;
1431			}
1432			return -ENOMEM;
1433		}
1434		set_page_private(page, (unsigned long)head);
1435		head = page;
1436	}
1437
1438	page = head;
1439	d_off = 0;
1440	for (i = 0; i < num_frags; i++) {
1441		skb_frag_t *f = &skb_shinfo(skb)->frags[i];
1442		u32 p_off, p_len, copied;
1443		struct page *p;
1444		u8 *vaddr;
1445
1446		skb_frag_foreach_page(f, skb_frag_off(f), skb_frag_size(f),
1447				      p, p_off, p_len, copied) {
1448			u32 copy, done = 0;
1449			vaddr = kmap_atomic(p);
1450
1451			while (done < p_len) {
1452				if (d_off == PAGE_SIZE) {
1453					d_off = 0;
1454					page = (struct page *)page_private(page);
1455				}
1456				copy = min_t(u32, PAGE_SIZE - d_off, p_len - done);
1457				memcpy(page_address(page) + d_off,
1458				       vaddr + p_off + done, copy);
1459				done += copy;
1460				d_off += copy;
1461			}
1462			kunmap_atomic(vaddr);
1463		}
1464	}
1465
1466	/* skb frags release userspace buffers */
1467	for (i = 0; i < num_frags; i++)
1468		skb_frag_unref(skb, i);
1469
1470	/* skb frags point to kernel buffers */
1471	for (i = 0; i < new_frags - 1; i++) {
1472		__skb_fill_page_desc(skb, i, head, 0, PAGE_SIZE);
1473		head = (struct page *)page_private(head);
1474	}
1475	__skb_fill_page_desc(skb, new_frags - 1, head, 0, d_off);
1476	skb_shinfo(skb)->nr_frags = new_frags;
1477
1478release:
1479	skb_zcopy_clear(skb, false);
1480	return 0;
1481}
1482EXPORT_SYMBOL_GPL(skb_copy_ubufs);
1483
1484/**
1485 *	skb_clone	-	duplicate an sk_buff
1486 *	@skb: buffer to clone
1487 *	@gfp_mask: allocation priority
1488 *
1489 *	Duplicate an &sk_buff. The new one is not owned by a socket. Both
1490 *	copies share the same packet data but not structure. The new
1491 *	buffer has a reference count of 1. If the allocation fails the
1492 *	function returns %NULL otherwise the new buffer is returned.
1493 *
1494 *	If this function is called from an interrupt gfp_mask() must be
1495 *	%GFP_ATOMIC.
1496 */
1497
1498struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
1499{
1500	struct sk_buff_fclones *fclones = container_of(skb,
1501						       struct sk_buff_fclones,
1502						       skb1);
1503	struct sk_buff *n;
1504
1505	if (skb_orphan_frags(skb, gfp_mask))
1506		return NULL;
1507
1508	if (skb->fclone == SKB_FCLONE_ORIG &&
1509	    refcount_read(&fclones->fclone_ref) == 1) {
1510		n = &fclones->skb2;
1511		refcount_set(&fclones->fclone_ref, 2);
1512	} else {
1513		if (skb_pfmemalloc(skb))
1514			gfp_mask |= __GFP_MEMALLOC;
1515
1516		n = kmem_cache_alloc(skbuff_head_cache, gfp_mask);
1517		if (!n)
1518			return NULL;
1519
1520		n->fclone = SKB_FCLONE_UNAVAILABLE;
1521	}
1522
1523	return __skb_clone(n, skb);
1524}
1525EXPORT_SYMBOL(skb_clone);
1526
1527void skb_headers_offset_update(struct sk_buff *skb, int off)
1528{
1529	/* Only adjust this if it actually is csum_start rather than csum */
1530	if (skb->ip_summed == CHECKSUM_PARTIAL)
1531		skb->csum_start += off;
1532	/* {transport,network,mac}_header and tail are relative to skb->head */
1533	skb->transport_header += off;
1534	skb->network_header   += off;
1535	if (skb_mac_header_was_set(skb))
1536		skb->mac_header += off;
1537	skb->inner_transport_header += off;
1538	skb->inner_network_header += off;
1539	skb->inner_mac_header += off;
1540}
1541EXPORT_SYMBOL(skb_headers_offset_update);
1542
1543void skb_copy_header(struct sk_buff *new, const struct sk_buff *old)
1544{
1545	__copy_skb_header(new, old);
1546
1547	skb_shinfo(new)->gso_size = skb_shinfo(old)->gso_size;
1548	skb_shinfo(new)->gso_segs = skb_shinfo(old)->gso_segs;
1549	skb_shinfo(new)->gso_type = skb_shinfo(old)->gso_type;
1550}
1551EXPORT_SYMBOL(skb_copy_header);
1552
1553static inline int skb_alloc_rx_flag(const struct sk_buff *skb)
1554{
1555	if (skb_pfmemalloc(skb))
1556		return SKB_ALLOC_RX;
1557	return 0;
1558}
1559
1560/**
1561 *	skb_copy	-	create private copy of an sk_buff
1562 *	@skb: buffer to copy
1563 *	@gfp_mask: allocation priority
1564 *
1565 *	Make a copy of both an &sk_buff and its data. This is used when the
1566 *	caller wishes to modify the data and needs a private copy of the
1567 *	data to alter. Returns %NULL on failure or the pointer to the buffer
1568 *	on success. The returned buffer has a reference count of 1.
1569 *
1570 *	As by-product this function converts non-linear &sk_buff to linear
1571 *	one, so that &sk_buff becomes completely private and caller is allowed
1572 *	to modify all the data of returned buffer. This means that this
1573 *	function is not recommended for use in circumstances when only
1574 *	header is going to be modified. Use pskb_copy() instead.
1575 */
1576
1577struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t gfp_mask)
1578{
1579	int headerlen = skb_headroom(skb);
1580	unsigned int size = skb_end_offset(skb) + skb->data_len;
1581	struct sk_buff *n = __alloc_skb(size, gfp_mask,
1582					skb_alloc_rx_flag(skb), NUMA_NO_NODE);
1583
1584	if (!n)
1585		return NULL;
1586
1587	/* Set the data pointer */
1588	skb_reserve(n, headerlen);
1589	/* Set the tail pointer and length */
1590	skb_put(n, skb->len);
1591
1592	BUG_ON(skb_copy_bits(skb, -headerlen, n->head, headerlen + skb->len));
1593
1594	skb_copy_header(n, skb);
1595	return n;
1596}
1597EXPORT_SYMBOL(skb_copy);
1598
1599/**
1600 *	__pskb_copy_fclone	-  create copy of an sk_buff with private head.
1601 *	@skb: buffer to copy
1602 *	@headroom: headroom of new skb
1603 *	@gfp_mask: allocation priority
1604 *	@fclone: if true allocate the copy of the skb from the fclone
1605 *	cache instead of the head cache; it is recommended to set this
1606 *	to true for the cases where the copy will likely be cloned
1607 *
1608 *	Make a copy of both an &sk_buff and part of its data, located
1609 *	in header. Fragmented data remain shared. This is used when
1610 *	the caller wishes to modify only header of &sk_buff and needs
1611 *	private copy of the header to alter. Returns %NULL on failure
1612 *	or the pointer to the buffer on success.
1613 *	The returned buffer has a reference count of 1.
1614 */
1615
1616struct sk_buff *__pskb_copy_fclone(struct sk_buff *skb, int headroom,
1617				   gfp_t gfp_mask, bool fclone)
1618{
1619	unsigned int size = skb_headlen(skb) + headroom;
1620	int flags = skb_alloc_rx_flag(skb) | (fclone ? SKB_ALLOC_FCLONE : 0);
1621	struct sk_buff *n = __alloc_skb(size, gfp_mask, flags, NUMA_NO_NODE);
1622
1623	if (!n)
1624		goto out;
1625
1626	/* Set the data pointer */
1627	skb_reserve(n, headroom);
1628	/* Set the tail pointer and length */
1629	skb_put(n, skb_headlen(skb));
1630	/* Copy the bytes */
1631	skb_copy_from_linear_data(skb, n->data, n->len);
1632
1633	n->truesize += skb->data_len;
1634	n->data_len  = skb->data_len;
1635	n->len	     = skb->len;
1636
1637	if (skb_shinfo(skb)->nr_frags) {
1638		int i;
1639
1640		if (skb_orphan_frags(skb, gfp_mask) ||
1641		    skb_zerocopy_clone(n, skb, gfp_mask)) {
1642			kfree_skb(n);
1643			n = NULL;
1644			goto out;
1645		}
1646		for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1647			skb_shinfo(n)->frags[i] = skb_shinfo(skb)->frags[i];
1648			skb_frag_ref(skb, i);
1649		}
1650		skb_shinfo(n)->nr_frags = i;
1651	}
1652
1653	if (skb_has_frag_list(skb)) {
1654		skb_shinfo(n)->frag_list = skb_shinfo(skb)->frag_list;
1655		skb_clone_fraglist(n);
1656	}
1657
1658	skb_copy_header(n, skb);
1659out:
1660	return n;
1661}
1662EXPORT_SYMBOL(__pskb_copy_fclone);
1663
1664/**
1665 *	pskb_expand_head - reallocate header of &sk_buff
1666 *	@skb: buffer to reallocate
1667 *	@nhead: room to add at head
1668 *	@ntail: room to add at tail
1669 *	@gfp_mask: allocation priority
1670 *
1671 *	Expands (or creates identical copy, if @nhead and @ntail are zero)
1672 *	header of @skb. &sk_buff itself is not changed. &sk_buff MUST have
1673 *	reference count of 1. Returns zero in the case of success or error,
1674 *	if expansion failed. In the last case, &sk_buff is not changed.
1675 *
1676 *	All the pointers pointing into skb header may change and must be
1677 *	reloaded after call to this function.
1678 */
1679
1680int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
1681		     gfp_t gfp_mask)
1682{
1683	int i, osize = skb_end_offset(skb);
1684	int size = osize + nhead + ntail;
1685	long off;
1686	u8 *data;
1687
1688	BUG_ON(nhead < 0);
1689
1690	BUG_ON(skb_shared(skb));
1691
1692	size = SKB_DATA_ALIGN(size);
1693
1694	if (skb_pfmemalloc(skb))
1695		gfp_mask |= __GFP_MEMALLOC;
1696	data = kmalloc_reserve(size + SKB_DATA_ALIGN(sizeof(struct skb_shared_info)),
1697			       gfp_mask, NUMA_NO_NODE, NULL);
1698	if (!data)
1699		goto nodata;
1700	size = SKB_WITH_OVERHEAD(ksize(data));
1701
1702	/* Copy only real data... and, alas, header. This should be
1703	 * optimized for the cases when header is void.
1704	 */
1705	memcpy(data + nhead, skb->head, skb_tail_pointer(skb) - skb->head);
1706
1707	memcpy((struct skb_shared_info *)(data + size),
1708	       skb_shinfo(skb),
1709	       offsetof(struct skb_shared_info, frags[skb_shinfo(skb)->nr_frags]));
1710
1711	/*
1712	 * if shinfo is shared we must drop the old head gracefully, but if it
1713	 * is not we can just drop the old head and let the existing refcount
1714	 * be since all we did is relocate the values
1715	 */
1716	if (skb_cloned(skb)) {
1717		if (skb_orphan_frags(skb, gfp_mask))
1718			goto nofrags;
1719		if (skb_zcopy(skb))
1720			refcount_inc(&skb_uarg(skb)->refcnt);
1721		for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
1722			skb_frag_ref(skb, i);
1723
1724		if (skb_has_frag_list(skb))
1725			skb_clone_fraglist(skb);
1726
1727		skb_release_data(skb);
1728	} else {
1729		skb_free_head(skb);
1730	}
1731	off = (data + nhead) - skb->head;
1732
1733	skb->head     = data;
1734	skb->head_frag = 0;
1735	skb->data    += off;
1736#ifdef NET_SKBUFF_DATA_USES_OFFSET
1737	skb->end      = size;
1738	off           = nhead;
1739#else
1740	skb->end      = skb->head + size;
1741#endif
1742	skb->tail	      += off;
1743	skb_headers_offset_update(skb, nhead);
1744	skb->cloned   = 0;
1745	skb->hdr_len  = 0;
1746	skb->nohdr    = 0;
1747	atomic_set(&skb_shinfo(skb)->dataref, 1);
1748
1749	skb_metadata_clear(skb);
1750
1751	/* It is not generally safe to change skb->truesize.
1752	 * For the moment, we really care of rx path, or
1753	 * when skb is orphaned (not attached to a socket).
1754	 */
1755	if (!skb->sk || skb->destructor == sock_edemux)
1756		skb->truesize += size - osize;
1757
1758	return 0;
1759
1760nofrags:
1761	kfree(data);
1762nodata:
1763	return -ENOMEM;
1764}
1765EXPORT_SYMBOL(pskb_expand_head);
1766
1767/* Make private copy of skb with writable head and some headroom */
1768
1769struct sk_buff *skb_realloc_headroom(struct sk_buff *skb, unsigned int headroom)
1770{
1771	struct sk_buff *skb2;
1772	int delta = headroom - skb_headroom(skb);
1773
1774	if (delta <= 0)
1775		skb2 = pskb_copy(skb, GFP_ATOMIC);
1776	else {
1777		skb2 = skb_clone(skb, GFP_ATOMIC);
1778		if (skb2 && pskb_expand_head(skb2, SKB_DATA_ALIGN(delta), 0,
1779					     GFP_ATOMIC)) {
1780			kfree_skb(skb2);
1781			skb2 = NULL;
1782		}
1783	}
1784	return skb2;
1785}
1786EXPORT_SYMBOL(skb_realloc_headroom);
1787
1788/**
1789 *	skb_copy_expand	-	copy and expand sk_buff
1790 *	@skb: buffer to copy
1791 *	@newheadroom: new free bytes at head
1792 *	@newtailroom: new free bytes at tail
1793 *	@gfp_mask: allocation priority
1794 *
1795 *	Make a copy of both an &sk_buff and its data and while doing so
1796 *	allocate additional space.
1797 *
1798 *	This is used when the caller wishes to modify the data and needs a
1799 *	private copy of the data to alter as well as more space for new fields.
1800 *	Returns %NULL on failure or the pointer to the buffer
1801 *	on success. The returned buffer has a reference count of 1.
1802 *
1803 *	You must pass %GFP_ATOMIC as the allocation priority if this function
1804 *	is called from an interrupt.
1805 */
1806struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
1807				int newheadroom, int newtailroom,
1808				gfp_t gfp_mask)
1809{
1810	/*
1811	 *	Allocate the copy buffer
1812	 */
1813	struct sk_buff *n = __alloc_skb(newheadroom + skb->len + newtailroom,
1814					gfp_mask, skb_alloc_rx_flag(skb),
1815					NUMA_NO_NODE);
1816	int oldheadroom = skb_headroom(skb);
1817	int head_copy_len, head_copy_off;
1818
1819	if (!n)
1820		return NULL;
1821
1822	skb_reserve(n, newheadroom);
1823
1824	/* Set the tail pointer and length */
1825	skb_put(n, skb->len);
1826
1827	head_copy_len = oldheadroom;
1828	head_copy_off = 0;
1829	if (newheadroom <= head_copy_len)
1830		head_copy_len = newheadroom;
1831	else
1832		head_copy_off = newheadroom - head_copy_len;
1833
1834	/* Copy the linear header and data. */
1835	BUG_ON(skb_copy_bits(skb, -head_copy_len, n->head + head_copy_off,
1836			     skb->len + head_copy_len));
1837
1838	skb_copy_header(n, skb);
1839
1840	skb_headers_offset_update(n, newheadroom - oldheadroom);
1841
1842	return n;
1843}
1844EXPORT_SYMBOL(skb_copy_expand);
1845
1846/**
1847 *	__skb_pad		-	zero pad the tail of an skb
1848 *	@skb: buffer to pad
1849 *	@pad: space to pad
1850 *	@free_on_error: free buffer on error
1851 *
1852 *	Ensure that a buffer is followed by a padding area that is zero
1853 *	filled. Used by network drivers which may DMA or transfer data
1854 *	beyond the buffer end onto the wire.
1855 *
1856 *	May return error in out of memory cases. The skb is freed on error
1857 *	if @free_on_error is true.
1858 */
1859
1860int __skb_pad(struct sk_buff *skb, int pad, bool free_on_error)
1861{
1862	int err;
1863	int ntail;
1864
1865	/* If the skbuff is non linear tailroom is always zero.. */
1866	if (!skb_cloned(skb) && skb_tailroom(skb) >= pad) {
1867		memset(skb->data+skb->len, 0, pad);
1868		return 0;
1869	}
1870
1871	ntail = skb->data_len + pad - (skb->end - skb->tail);
1872	if (likely(skb_cloned(skb) || ntail > 0)) {
1873		err = pskb_expand_head(skb, 0, ntail, GFP_ATOMIC);
1874		if (unlikely(err))
1875			goto free_skb;
1876	}
1877
1878	/* FIXME: The use of this function with non-linear skb's really needs
1879	 * to be audited.
1880	 */
1881	err = skb_linearize(skb);
1882	if (unlikely(err))
1883		goto free_skb;
1884
1885	memset(skb->data + skb->len, 0, pad);
1886	return 0;
1887
1888free_skb:
1889	if (free_on_error)
1890		kfree_skb(skb);
1891	return err;
1892}
1893EXPORT_SYMBOL(__skb_pad);
1894
1895/**
1896 *	pskb_put - add data to the tail of a potentially fragmented buffer
1897 *	@skb: start of the buffer to use
1898 *	@tail: tail fragment of the buffer to use
1899 *	@len: amount of data to add
1900 *
1901 *	This function extends the used data area of the potentially
1902 *	fragmented buffer. @tail must be the last fragment of @skb -- or
1903 *	@skb itself. If this would exceed the total buffer size the kernel
1904 *	will panic. A pointer to the first byte of the extra data is
1905 *	returned.
1906 */
1907
1908void *pskb_put(struct sk_buff *skb, struct sk_buff *tail, int len)
1909{
1910	if (tail != skb) {
1911		skb->data_len += len;
1912		skb->len += len;
1913	}
1914	return skb_put(tail, len);
1915}
1916EXPORT_SYMBOL_GPL(pskb_put);
1917
1918/**
1919 *	skb_put - add data to a buffer
1920 *	@skb: buffer to use
1921 *	@len: amount of data to add
1922 *
1923 *	This function extends the used data area of the buffer. If this would
1924 *	exceed the total buffer size the kernel will panic. A pointer to the
1925 *	first byte of the extra data is returned.
1926 */
1927void *skb_put(struct sk_buff *skb, unsigned int len)
1928{
1929	void *tmp = skb_tail_pointer(skb);
1930	SKB_LINEAR_ASSERT(skb);
1931	skb->tail += len;
1932	skb->len  += len;
1933	if (unlikely(skb->tail > skb->end))
1934		skb_over_panic(skb, len, __builtin_return_address(0));
1935	return tmp;
1936}
1937EXPORT_SYMBOL(skb_put);
1938
1939/**
1940 *	skb_push - add data to the start of a buffer
1941 *	@skb: buffer to use
1942 *	@len: amount of data to add
1943 *
1944 *	This function extends the used data area of the buffer at the buffer
1945 *	start. If this would exceed the total buffer headroom the kernel will
1946 *	panic. A pointer to the first byte of the extra data is returned.
1947 */
1948void *skb_push(struct sk_buff *skb, unsigned int len)
1949{
1950	skb->data -= len;
1951	skb->len  += len;
1952	if (unlikely(skb->data < skb->head))
1953		skb_under_panic(skb, len, __builtin_return_address(0));
1954	return skb->data;
1955}
1956EXPORT_SYMBOL(skb_push);
1957
1958/**
1959 *	skb_pull - remove data from the start of a buffer
1960 *	@skb: buffer to use
1961 *	@len: amount of data to remove
1962 *
1963 *	This function removes data from the start of a buffer, returning
1964 *	the memory to the headroom. A pointer to the next data in the buffer
1965 *	is returned. Once the data has been pulled future pushes will overwrite
1966 *	the old data.
1967 */
1968void *skb_pull(struct sk_buff *skb, unsigned int len)
1969{
1970	return skb_pull_inline(skb, len);
1971}
1972EXPORT_SYMBOL(skb_pull);
1973
1974/**
1975 *	skb_trim - remove end from a buffer
1976 *	@skb: buffer to alter
1977 *	@len: new length
1978 *
1979 *	Cut the length of a buffer down by removing data from the tail. If
1980 *	the buffer is already under the length specified it is not modified.
1981 *	The skb must be linear.
1982 */
1983void skb_trim(struct sk_buff *skb, unsigned int len)
1984{
1985	if (skb->len > len)
1986		__skb_trim(skb, len);
1987}
1988EXPORT_SYMBOL(skb_trim);
1989
1990/* Trims skb to length len. It can change skb pointers.
1991 */
1992
1993int ___pskb_trim(struct sk_buff *skb, unsigned int len)
1994{
1995	struct sk_buff **fragp;
1996	struct sk_buff *frag;
1997	int offset = skb_headlen(skb);
1998	int nfrags = skb_shinfo(skb)->nr_frags;
1999	int i;
2000	int err;
2001
2002	if (skb_cloned(skb) &&
2003	    unlikely((err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC))))
2004		return err;
2005
2006	i = 0;
2007	if (offset >= len)
2008		goto drop_pages;
2009
2010	for (; i < nfrags; i++) {
2011		int end = offset + skb_frag_size(&skb_shinfo(skb)->frags[i]);
2012
2013		if (end < len) {
2014			offset = end;
2015			continue;
2016		}
2017
2018		skb_frag_size_set(&skb_shinfo(skb)->frags[i++], len - offset);
2019
2020drop_pages:
2021		skb_shinfo(skb)->nr_frags = i;
2022
2023		for (; i < nfrags; i++)
2024			skb_frag_unref(skb, i);
2025
2026		if (skb_has_frag_list(skb))
2027			skb_drop_fraglist(skb);
2028		goto done;
2029	}
2030
2031	for (fragp = &skb_shinfo(skb)->frag_list; (frag = *fragp);
2032	     fragp = &frag->next) {
2033		int end = offset + frag->len;
2034
2035		if (skb_shared(frag)) {
2036			struct sk_buff *nfrag;
2037
2038			nfrag = skb_clone(frag, GFP_ATOMIC);
2039			if (unlikely(!nfrag))
2040				return -ENOMEM;
2041
2042			nfrag->next = frag->next;
2043			consume_skb(frag);
2044			frag = nfrag;
2045			*fragp = frag;
2046		}
2047
2048		if (end < len) {
2049			offset = end;
2050			continue;
2051		}
2052
2053		if (end > len &&
2054		    unlikely((err = pskb_trim(frag, len - offset))))
2055			return err;
2056
2057		if (frag->next)
2058			skb_drop_list(&frag->next);
2059		break;
2060	}
2061
2062done:
2063	if (len > skb_headlen(skb)) {
2064		skb->data_len -= skb->len - len;
2065		skb->len       = len;
2066	} else {
2067		skb->len       = len;
2068		skb->data_len  = 0;
2069		skb_set_tail_pointer(skb, len);
2070	}
2071
2072	if (!skb->sk || skb->destructor == sock_edemux)
2073		skb_condense(skb);
2074	return 0;
2075}
2076EXPORT_SYMBOL(___pskb_trim);
2077
2078/* Note : use pskb_trim_rcsum() instead of calling this directly
2079 */
2080int pskb_trim_rcsum_slow(struct sk_buff *skb, unsigned int len)
2081{
2082	if (skb->ip_summed == CHECKSUM_COMPLETE) {
2083		int delta = skb->len - len;
2084
2085		skb->csum = csum_block_sub(skb->csum,
2086					   skb_checksum(skb, len, delta, 0),
2087					   len);
2088	} else if (skb->ip_summed == CHECKSUM_PARTIAL) {
2089		int hdlen = (len > skb_headlen(skb)) ? skb_headlen(skb) : len;
2090		int offset = skb_checksum_start_offset(skb) + skb->csum_offset;
2091
2092		if (offset + sizeof(__sum16) > hdlen)
2093			return -EINVAL;
2094	}
2095	return __pskb_trim(skb, len);
2096}
2097EXPORT_SYMBOL(pskb_trim_rcsum_slow);
2098
2099/**
2100 *	__pskb_pull_tail - advance tail of skb header
2101 *	@skb: buffer to reallocate
2102 *	@delta: number of bytes to advance tail
2103 *
2104 *	The function makes a sense only on a fragmented &sk_buff,
2105 *	it expands header moving its tail forward and copying necessary
2106 *	data from fragmented part.
2107 *
2108 *	&sk_buff MUST have reference count of 1.
2109 *
2110 *	Returns %NULL (and &sk_buff does not change) if pull failed
2111 *	or value of new tail of skb in the case of success.
2112 *
2113 *	All the pointers pointing into skb header may change and must be
2114 *	reloaded after call to this function.
2115 */
2116
2117/* Moves tail of skb head forward, copying data from fragmented part,
2118 * when it is necessary.
2119 * 1. It may fail due to malloc failure.
2120 * 2. It may change skb pointers.
2121 *
2122 * It is pretty complicated. Luckily, it is called only in exceptional cases.
2123 */
2124void *__pskb_pull_tail(struct sk_buff *skb, int delta)
2125{
2126	/* If skb has not enough free space at tail, get new one
2127	 * plus 128 bytes for future expansions. If we have enough
2128	 * room at tail, reallocate without expansion only if skb is cloned.
2129	 */
2130	int i, k, eat = (skb->tail + delta) - skb->end;
2131
2132	if (eat > 0 || skb_cloned(skb)) {
2133		if (pskb_expand_head(skb, 0, eat > 0 ? eat + 128 : 0,
2134				     GFP_ATOMIC))
2135			return NULL;
2136	}
2137
2138	BUG_ON(skb_copy_bits(skb, skb_headlen(skb),
2139			     skb_tail_pointer(skb), delta));
2140
2141	/* Optimization: no fragments, no reasons to preestimate
2142	 * size of pulled pages. Superb.
2143	 */
2144	if (!skb_has_frag_list(skb))
2145		goto pull_pages;
2146
2147	/* Estimate size of pulled pages. */
2148	eat = delta;
2149	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2150		int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
2151
2152		if (size >= eat)
2153			goto pull_pages;
2154		eat -= size;
2155	}
2156
2157	/* If we need update frag list, we are in troubles.
2158	 * Certainly, it is possible to add an offset to skb data,
2159	 * but taking into account that pulling is expected to
2160	 * be very rare operation, it is worth to fight against
2161	 * further bloating skb head and crucify ourselves here instead.
2162	 * Pure masohism, indeed. 8)8)
2163	 */
2164	if (eat) {
2165		struct sk_buff *list = skb_shinfo(skb)->frag_list;
2166		struct sk_buff *clone = NULL;
2167		struct sk_buff *insp = NULL;
2168
2169		do {
2170			if (list->len <= eat) {
2171				/* Eaten as whole. */
2172				eat -= list->len;
2173				list = list->next;
2174				insp = list;
2175			} else {
2176				/* Eaten partially. */
2177
2178				if (skb_shared(list)) {
2179					/* Sucks! We need to fork list. :-( */
2180					clone = skb_clone(list, GFP_ATOMIC);
2181					if (!clone)
2182						return NULL;
2183					insp = list->next;
2184					list = clone;
2185				} else {
2186					/* This may be pulled without
2187					 * problems. */
2188					insp = list;
2189				}
2190				if (!pskb_pull(list, eat)) {
2191					kfree_skb(clone);
2192					return NULL;
2193				}
2194				break;
2195			}
2196		} while (eat);
2197
2198		/* Free pulled out fragments. */
2199		while ((list = skb_shinfo(skb)->frag_list) != insp) {
2200			skb_shinfo(skb)->frag_list = list->next;
2201			kfree_skb(list);
2202		}
2203		/* And insert new clone at head. */
2204		if (clone) {
2205			clone->next = list;
2206			skb_shinfo(skb)->frag_list = clone;
2207		}
2208	}
2209	/* Success! Now we may commit changes to skb data. */
2210
2211pull_pages:
2212	eat = delta;
2213	k = 0;
2214	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2215		int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
2216
2217		if (size <= eat) {
2218			skb_frag_unref(skb, i);
2219			eat -= size;
2220		} else {
2221			skb_frag_t *frag = &skb_shinfo(skb)->frags[k];
2222
2223			*frag = skb_shinfo(skb)->frags[i];
2224			if (eat) {
2225				skb_frag_off_add(frag, eat);
2226				skb_frag_size_sub(frag, eat);
2227				if (!i)
2228					goto end;
2229				eat = 0;
2230			}
2231			k++;
2232		}
2233	}
2234	skb_shinfo(skb)->nr_frags = k;
2235
2236end:
2237	skb->tail     += delta;
2238	skb->data_len -= delta;
2239
2240	if (!skb->data_len)
2241		skb_zcopy_clear(skb, false);
2242
2243	return skb_tail_pointer(skb);
2244}
2245EXPORT_SYMBOL(__pskb_pull_tail);
2246
2247/**
2248 *	skb_copy_bits - copy bits from skb to kernel buffer
2249 *	@skb: source skb
2250 *	@offset: offset in source
2251 *	@to: destination buffer
2252 *	@len: number of bytes to copy
2253 *
2254 *	Copy the specified number of bytes from the source skb to the
2255 *	destination buffer.
2256 *
2257 *	CAUTION ! :
2258 *		If its prototype is ever changed,
2259 *		check arch/{*}/net/{*}.S files,
2260 *		since it is called from BPF assembly code.
2261 */
2262int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len)
2263{
2264	int start = skb_headlen(skb);
2265	struct sk_buff *frag_iter;
2266	int i, copy;
2267
2268	if (offset > (int)skb->len - len)
2269		goto fault;
2270
2271	/* Copy header. */
2272	if ((copy = start - offset) > 0) {
2273		if (copy > len)
2274			copy = len;
2275		skb_copy_from_linear_data_offset(skb, offset, to, copy);
2276		if ((len -= copy) == 0)
2277			return 0;
2278		offset += copy;
2279		to     += copy;
2280	}
2281
2282	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2283		int end;
2284		skb_frag_t *f = &skb_shinfo(skb)->frags[i];
2285
2286		WARN_ON(start > offset + len);
2287
2288		end = start + skb_frag_size(f);
2289		if ((copy = end - offset) > 0) {
2290			u32 p_off, p_len, copied;
2291			struct page *p;
2292			u8 *vaddr;
2293
2294			if (copy > len)
2295				copy = len;
2296
2297			skb_frag_foreach_page(f,
2298					      skb_frag_off(f) + offset - start,
2299					      copy, p, p_off, p_len, copied) {
2300				vaddr = kmap_atomic(p);
2301				memcpy(to + copied, vaddr + p_off, p_len);
2302				kunmap_atomic(vaddr);
2303			}
2304
2305			if ((len -= copy) == 0)
2306				return 0;
2307			offset += copy;
2308			to     += copy;
2309		}
2310		start = end;
2311	}
2312
2313	skb_walk_frags(skb, frag_iter) {
2314		int end;
2315
2316		WARN_ON(start > offset + len);
2317
2318		end = start + frag_iter->len;
2319		if ((copy = end - offset) > 0) {
2320			if (copy > len)
2321				copy = len;
2322			if (skb_copy_bits(frag_iter, offset - start, to, copy))
2323				goto fault;
2324			if ((len -= copy) == 0)
2325				return 0;
2326			offset += copy;
2327			to     += copy;
2328		}
2329		start = end;
2330	}
2331
2332	if (!len)
2333		return 0;
2334
2335fault:
2336	return -EFAULT;
2337}
2338EXPORT_SYMBOL(skb_copy_bits);
2339
2340/*
2341 * Callback from splice_to_pipe(), if we need to release some pages
2342 * at the end of the spd in case we error'ed out in filling the pipe.
2343 */
2344static void sock_spd_release(struct splice_pipe_desc *spd, unsigned int i)
2345{
2346	put_page(spd->pages[i]);
2347}
2348
2349static struct page *linear_to_page(struct page *page, unsigned int *len,
2350				   unsigned int *offset,
2351				   struct sock *sk)
2352{
2353	struct page_frag *pfrag = sk_page_frag(sk);
2354
2355	if (!sk_page_frag_refill(sk, pfrag))
2356		return NULL;
2357
2358	*len = min_t(unsigned int, *len, pfrag->size - pfrag->offset);
2359
2360	memcpy(page_address(pfrag->page) + pfrag->offset,
2361	       page_address(page) + *offset, *len);
2362	*offset = pfrag->offset;
2363	pfrag->offset += *len;
2364
2365	return pfrag->page;
2366}
2367
2368static bool spd_can_coalesce(const struct splice_pipe_desc *spd,
2369			     struct page *page,
2370			     unsigned int offset)
2371{
2372	return	spd->nr_pages &&
2373		spd->pages[spd->nr_pages - 1] == page &&
2374		(spd->partial[spd->nr_pages - 1].offset +
2375		 spd->partial[spd->nr_pages - 1].len == offset);
2376}
2377
2378/*
2379 * Fill page/offset/length into spd, if it can hold more pages.
2380 */
2381static bool spd_fill_page(struct splice_pipe_desc *spd,
2382			  struct pipe_inode_info *pipe, struct page *page,
2383			  unsigned int *len, unsigned int offset,
2384			  bool linear,
2385			  struct sock *sk)
2386{
2387	if (unlikely(spd->nr_pages == MAX_SKB_FRAGS))
2388		return true;
2389
2390	if (linear) {
2391		page = linear_to_page(page, len, &offset, sk);
2392		if (!page)
2393			return true;
2394	}
2395	if (spd_can_coalesce(spd, page, offset)) {
2396		spd->partial[spd->nr_pages - 1].len += *len;
2397		return false;
2398	}
2399	get_page(page);
2400	spd->pages[spd->nr_pages] = page;
2401	spd->partial[spd->nr_pages].len = *len;
2402	spd->partial[spd->nr_pages].offset = offset;
2403	spd->nr_pages++;
2404
2405	return false;
2406}
2407
2408static bool __splice_segment(struct page *page, unsigned int poff,
2409			     unsigned int plen, unsigned int *off,
2410			     unsigned int *len,
2411			     struct splice_pipe_desc *spd, bool linear,
2412			     struct sock *sk,
2413			     struct pipe_inode_info *pipe)
2414{
2415	if (!*len)
2416		return true;
2417
2418	/* skip this segment if already processed */
2419	if (*off >= plen) {
2420		*off -= plen;
2421		return false;
2422	}
2423
2424	/* ignore any bits we already processed */
2425	poff += *off;
2426	plen -= *off;
2427	*off = 0;
2428
2429	do {
2430		unsigned int flen = min(*len, plen);
2431
2432		if (spd_fill_page(spd, pipe, page, &flen, poff,
2433				  linear, sk))
2434			return true;
2435		poff += flen;
2436		plen -= flen;
2437		*len -= flen;
2438	} while (*len && plen);
2439
2440	return false;
2441}
2442
2443/*
2444 * Map linear and fragment data from the skb to spd. It reports true if the
2445 * pipe is full or if we already spliced the requested length.
2446 */
2447static bool __skb_splice_bits(struct sk_buff *skb, struct pipe_inode_info *pipe,
2448			      unsigned int *offset, unsigned int *len,
2449			      struct splice_pipe_desc *spd, struct sock *sk)
2450{
2451	int seg;
2452	struct sk_buff *iter;
2453
2454	/* map the linear part :
2455	 * If skb->head_frag is set, this 'linear' part is backed by a
2456	 * fragment, and if the head is not shared with any clones then
2457	 * we can avoid a copy since we own the head portion of this page.
2458	 */
2459	if (__splice_segment(virt_to_page(skb->data),
2460			     (unsigned long) skb->data & (PAGE_SIZE - 1),
2461			     skb_headlen(skb),
2462			     offset, len, spd,
2463			     skb_head_is_locked(skb),
2464			     sk, pipe))
2465		return true;
2466
2467	/*
2468	 * then map the fragments
2469	 */
2470	for (seg = 0; seg < skb_shinfo(skb)->nr_frags; seg++) {
2471		const skb_frag_t *f = &skb_shinfo(skb)->frags[seg];
2472
2473		if (__splice_segment(skb_frag_page(f),
2474				     skb_frag_off(f), skb_frag_size(f),
2475				     offset, len, spd, false, sk, pipe))
2476			return true;
2477	}
2478
2479	skb_walk_frags(skb, iter) {
2480		if (*offset >= iter->len) {
2481			*offset -= iter->len;
2482			continue;
2483		}
2484		/* __skb_splice_bits() only fails if the output has no room
2485		 * left, so no point in going over the frag_list for the error
2486		 * case.
2487		 */
2488		if (__skb_splice_bits(iter, pipe, offset, len, spd, sk))
2489			return true;
2490	}
2491
2492	return false;
2493}
2494
2495/*
2496 * Map data from the skb to a pipe. Should handle both the linear part,
2497 * the fragments, and the frag list.
2498 */
2499int skb_splice_bits(struct sk_buff *skb, struct sock *sk, unsigned int offset,
2500		    struct pipe_inode_info *pipe, unsigned int tlen,
2501		    unsigned int flags)
2502{
2503	struct partial_page partial[MAX_SKB_FRAGS];
2504	struct page *pages[MAX_SKB_FRAGS];
2505	struct splice_pipe_desc spd = {
2506		.pages = pages,
2507		.partial = partial,
2508		.nr_pages_max = MAX_SKB_FRAGS,
2509		.ops = &nosteal_pipe_buf_ops,
2510		.spd_release = sock_spd_release,
2511	};
2512	int ret = 0;
2513
2514	__skb_splice_bits(skb, pipe, &offset, &tlen, &spd, sk);
2515
2516	if (spd.nr_pages)
2517		ret = splice_to_pipe(pipe, &spd);
2518
2519	return ret;
2520}
2521EXPORT_SYMBOL_GPL(skb_splice_bits);
2522
2523static int sendmsg_unlocked(struct sock *sk, struct msghdr *msg,
2524			    struct kvec *vec, size_t num, size_t size)
2525{
2526	struct socket *sock = sk->sk_socket;
2527
2528	if (!sock)
2529		return -EINVAL;
2530	return kernel_sendmsg(sock, msg, vec, num, size);
2531}
2532
2533static int sendpage_unlocked(struct sock *sk, struct page *page, int offset,
2534			     size_t size, int flags)
2535{
2536	struct socket *sock = sk->sk_socket;
2537
2538	if (!sock)
2539		return -EINVAL;
2540	return kernel_sendpage(sock, page, offset, size, flags);
2541}
2542
2543typedef int (*sendmsg_func)(struct sock *sk, struct msghdr *msg,
2544			    struct kvec *vec, size_t num, size_t size);
2545typedef int (*sendpage_func)(struct sock *sk, struct page *page, int offset,
2546			     size_t size, int flags);
2547static int __skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset,
2548			   int len, sendmsg_func sendmsg, sendpage_func sendpage)
2549{
2550	unsigned int orig_len = len;
2551	struct sk_buff *head = skb;
2552	unsigned short fragidx;
2553	int slen, ret;
2554
2555do_frag_list:
2556
2557	/* Deal with head data */
2558	while (offset < skb_headlen(skb) && len) {
2559		struct kvec kv;
2560		struct msghdr msg;
2561
2562		slen = min_t(int, len, skb_headlen(skb) - offset);
2563		kv.iov_base = skb->data + offset;
2564		kv.iov_len = slen;
2565		memset(&msg, 0, sizeof(msg));
2566		msg.msg_flags = MSG_DONTWAIT;
2567
2568		ret = INDIRECT_CALL_2(sendmsg, kernel_sendmsg_locked,
2569				      sendmsg_unlocked, sk, &msg, &kv, 1, slen);
2570		if (ret <= 0)
2571			goto error;
2572
2573		offset += ret;
2574		len -= ret;
2575	}
2576
2577	/* All the data was skb head? */
2578	if (!len)
2579		goto out;
2580
2581	/* Make offset relative to start of frags */
2582	offset -= skb_headlen(skb);
2583
2584	/* Find where we are in frag list */
2585	for (fragidx = 0; fragidx < skb_shinfo(skb)->nr_frags; fragidx++) {
2586		skb_frag_t *frag  = &skb_shinfo(skb)->frags[fragidx];
2587
2588		if (offset < skb_frag_size(frag))
2589			break;
2590
2591		offset -= skb_frag_size(frag);
2592	}
2593
2594	for (; len && fragidx < skb_shinfo(skb)->nr_frags; fragidx++) {
2595		skb_frag_t *frag  = &skb_shinfo(skb)->frags[fragidx];
2596
2597		slen = min_t(size_t, len, skb_frag_size(frag) - offset);
2598
2599		while (slen) {
2600			ret = INDIRECT_CALL_2(sendpage, kernel_sendpage_locked,
2601					      sendpage_unlocked, sk,
2602					      skb_frag_page(frag),
2603					      skb_frag_off(frag) + offset,
2604					      slen, MSG_DONTWAIT);
2605			if (ret <= 0)
2606				goto error;
2607
2608			len -= ret;
2609			offset += ret;
2610			slen -= ret;
2611		}
2612
2613		offset = 0;
2614	}
2615
2616	if (len) {
2617		/* Process any frag lists */
2618
2619		if (skb == head) {
2620			if (skb_has_frag_list(skb)) {
2621				skb = skb_shinfo(skb)->frag_list;
2622				goto do_frag_list;
2623			}
2624		} else if (skb->next) {
2625			skb = skb->next;
2626			goto do_frag_list;
2627		}
2628	}
2629
2630out:
2631	return orig_len - len;
2632
2633error:
2634	return orig_len == len ? ret : orig_len - len;
2635}
2636
2637/* Send skb data on a socket. Socket must be locked. */
2638int skb_send_sock_locked(struct sock *sk, struct sk_buff *skb, int offset,
2639			 int len)
2640{
2641	return __skb_send_sock(sk, skb, offset, len, kernel_sendmsg_locked,
2642			       kernel_sendpage_locked);
2643}
2644EXPORT_SYMBOL_GPL(skb_send_sock_locked);
2645
2646/* Send skb data on a socket. Socket must be unlocked. */
2647int skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset, int len)
2648{
2649	return __skb_send_sock(sk, skb, offset, len, sendmsg_unlocked,
2650			       sendpage_unlocked);
2651}
2652
2653/**
2654 *	skb_store_bits - store bits from kernel buffer to skb
2655 *	@skb: destination buffer
2656 *	@offset: offset in destination
2657 *	@from: source buffer
2658 *	@len: number of bytes to copy
2659 *
2660 *	Copy the specified number of bytes from the source buffer to the
2661 *	destination skb.  This function handles all the messy bits of
2662 *	traversing fragment lists and such.
2663 */
2664
2665int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len)
2666{
2667	int start = skb_headlen(skb);
2668	struct sk_buff *frag_iter;
2669	int i, copy;
2670
2671	if (offset > (int)skb->len - len)
2672		goto fault;
2673
2674	if ((copy = start - offset) > 0) {
2675		if (copy > len)
2676			copy = len;
2677		skb_copy_to_linear_data_offset(skb, offset, from, copy);
2678		if ((len -= copy) == 0)
2679			return 0;
2680		offset += copy;
2681		from += copy;
2682	}
2683
2684	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2685		skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
2686		int end;
2687
2688		WARN_ON(start > offset + len);
2689
2690		end = start + skb_frag_size(frag);
2691		if ((copy = end - offset) > 0) {
2692			u32 p_off, p_len, copied;
2693			struct page *p;
2694			u8 *vaddr;
2695
2696			if (copy > len)
2697				copy = len;
2698
2699			skb_frag_foreach_page(frag,
2700					      skb_frag_off(frag) + offset - start,
2701					      copy, p, p_off, p_len, copied) {
2702				vaddr = kmap_atomic(p);
2703				memcpy(vaddr + p_off, from + copied, p_len);
2704				kunmap_atomic(vaddr);
2705			}
2706
2707			if ((len -= copy) == 0)
2708				return 0;
2709			offset += copy;
2710			from += copy;
2711		}
2712		start = end;
2713	}
2714
2715	skb_walk_frags(skb, frag_iter) {
2716		int end;
2717
2718		WARN_ON(start > offset + len);
2719
2720		end = start + frag_iter->len;
2721		if ((copy = end - offset) > 0) {
2722			if (copy > len)
2723				copy = len;
2724			if (skb_store_bits(frag_iter, offset - start,
2725					   from, copy))
2726				goto fault;
2727			if ((len -= copy) == 0)
2728				return 0;
2729			offset += copy;
2730			from += copy;
2731		}
2732		start = end;
2733	}
2734	if (!len)
2735		return 0;
2736
2737fault:
2738	return -EFAULT;
2739}
2740EXPORT_SYMBOL(skb_store_bits);
2741
2742/* Checksum skb data. */
2743__wsum __skb_checksum(const struct sk_buff *skb, int offset, int len,
2744		      __wsum csum, const struct skb_checksum_ops *ops)
2745{
2746	int start = skb_headlen(skb);
2747	int i, copy = start - offset;
2748	struct sk_buff *frag_iter;
2749	int pos = 0;
2750
2751	/* Checksum header. */
2752	if (copy > 0) {
2753		if (copy > len)
2754			copy = len;
2755		csum = INDIRECT_CALL_1(ops->update, csum_partial_ext,
2756				       skb->data + offset, copy, csum);
2757		if ((len -= copy) == 0)
2758			return csum;
2759		offset += copy;
2760		pos	= copy;
2761	}
2762
2763	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2764		int end;
2765		skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
2766
2767		WARN_ON(start > offset + len);
2768
2769		end = start + skb_frag_size(frag);
2770		if ((copy = end - offset) > 0) {
2771			u32 p_off, p_len, copied;
2772			struct page *p;
2773			__wsum csum2;
2774			u8 *vaddr;
2775
2776			if (copy > len)
2777				copy = len;
2778
2779			skb_frag_foreach_page(frag,
2780					      skb_frag_off(frag) + offset - start,
2781					      copy, p, p_off, p_len, copied) {
2782				vaddr = kmap_atomic(p);
2783				csum2 = INDIRECT_CALL_1(ops->update,
2784							csum_partial_ext,
2785							vaddr + p_off, p_len, 0);
2786				kunmap_atomic(vaddr);
2787				csum = INDIRECT_CALL_1(ops->combine,
2788						       csum_block_add_ext, csum,
2789						       csum2, pos, p_len);
2790				pos += p_len;
2791			}
2792
2793			if (!(len -= copy))
2794				return csum;
2795			offset += copy;
2796		}
2797		start = end;
2798	}
2799
2800	skb_walk_frags(skb, frag_iter) {
2801		int end;
2802
2803		WARN_ON(start > offset + len);
2804
2805		end = start + frag_iter->len;
2806		if ((copy = end - offset) > 0) {
2807			__wsum csum2;
2808			if (copy > len)
2809				copy = len;
2810			csum2 = __skb_checksum(frag_iter, offset - start,
2811					       copy, 0, ops);
2812			csum = INDIRECT_CALL_1(ops->combine, csum_block_add_ext,
2813					       csum, csum2, pos, copy);
2814			if ((len -= copy) == 0)
2815				return csum;
2816			offset += copy;
2817			pos    += copy;
2818		}
2819		start = end;
2820	}
2821	BUG_ON(len);
2822
2823	return csum;
2824}
2825EXPORT_SYMBOL(__skb_checksum);
2826
2827__wsum skb_checksum(const struct sk_buff *skb, int offset,
2828		    int len, __wsum csum)
2829{
2830	const struct skb_checksum_ops ops = {
2831		.update  = csum_partial_ext,
2832		.combine = csum_block_add_ext,
2833	};
2834
2835	return __skb_checksum(skb, offset, len, csum, &ops);
2836}
2837EXPORT_SYMBOL(skb_checksum);
2838
2839/* Both of above in one bottle. */
2840
2841__wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset,
2842				    u8 *to, int len)
2843{
2844	int start = skb_headlen(skb);
2845	int i, copy = start - offset;
2846	struct sk_buff *frag_iter;
2847	int pos = 0;
2848	__wsum csum = 0;
2849
2850	/* Copy header. */
2851	if (copy > 0) {
2852		if (copy > len)
2853			copy = len;
2854		csum = csum_partial_copy_nocheck(skb->data + offset, to,
2855						 copy);
2856		if ((len -= copy) == 0)
2857			return csum;
2858		offset += copy;
2859		to     += copy;
2860		pos	= copy;
2861	}
2862
2863	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2864		int end;
2865
2866		WARN_ON(start > offset + len);
2867
2868		end = start + skb_frag_size(&skb_shinfo(skb)->frags[i]);
2869		if ((copy = end - offset) > 0) {
2870			skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
2871			u32 p_off, p_len, copied;
2872			struct page *p;
2873			__wsum csum2;
2874			u8 *vaddr;
2875
2876			if (copy > len)
2877				copy = len;
2878
2879			skb_frag_foreach_page(frag,
2880					      skb_frag_off(frag) + offset - start,
2881					      copy, p, p_off, p_len, copied) {
2882				vaddr = kmap_atomic(p);
2883				csum2 = csum_partial_copy_nocheck(vaddr + p_off,
2884								  to + copied,
2885								  p_len);
2886				kunmap_atomic(vaddr);
2887				csum = csum_block_add(csum, csum2, pos);
2888				pos += p_len;
2889			}
2890
2891			if (!(len -= copy))
2892				return csum;
2893			offset += copy;
2894			to     += copy;
2895		}
2896		start = end;
2897	}
2898
2899	skb_walk_frags(skb, frag_iter) {
2900		__wsum csum2;
2901		int end;
2902
2903		WARN_ON(start > offset + len);
2904
2905		end = start + frag_iter->len;
2906		if ((copy = end - offset) > 0) {
2907			if (copy > len)
2908				copy = len;
2909			csum2 = skb_copy_and_csum_bits(frag_iter,
2910						       offset - start,
2911						       to, copy);
2912			csum = csum_block_add(csum, csum2, pos);
2913			if ((len -= copy) == 0)
2914				return csum;
2915			offset += copy;
2916			to     += copy;
2917			pos    += copy;
2918		}
2919		start = end;
2920	}
2921	BUG_ON(len);
2922	return csum;
2923}
2924EXPORT_SYMBOL(skb_copy_and_csum_bits);
2925
2926__sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len)
2927{
2928	__sum16 sum;
2929
2930	sum = csum_fold(skb_checksum(skb, 0, len, skb->csum));
2931	/* See comments in __skb_checksum_complete(). */
2932	if (likely(!sum)) {
2933		if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
2934		    !skb->csum_complete_sw)
2935			netdev_rx_csum_fault(skb->dev, skb);
2936	}
2937	if (!skb_shared(skb))
2938		skb->csum_valid = !sum;
2939	return sum;
2940}
2941EXPORT_SYMBOL(__skb_checksum_complete_head);
2942
2943/* This function assumes skb->csum already holds pseudo header's checksum,
2944 * which has been changed from the hardware checksum, for example, by
2945 * __skb_checksum_validate_complete(). And, the original skb->csum must
2946 * have been validated unsuccessfully for CHECKSUM_COMPLETE case.
2947 *
2948 * It returns non-zero if the recomputed checksum is still invalid, otherwise
2949 * zero. The new checksum is stored back into skb->csum unless the skb is
2950 * shared.
2951 */
2952__sum16 __skb_checksum_complete(struct sk_buff *skb)
2953{
2954	__wsum csum;
2955	__sum16 sum;
2956
2957	csum = skb_checksum(skb, 0, skb->len, 0);
2958
2959	sum = csum_fold(csum_add(skb->csum, csum));
2960	/* This check is inverted, because we already knew the hardware
2961	 * checksum is invalid before calling this function. So, if the
2962	 * re-computed checksum is valid instead, then we have a mismatch
2963	 * between the original skb->csum and skb_checksum(). This means either
2964	 * the original hardware checksum is incorrect or we screw up skb->csum
2965	 * when moving skb->data around.
2966	 */
2967	if (likely(!sum)) {
2968		if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
2969		    !skb->csum_complete_sw)
2970			netdev_rx_csum_fault(skb->dev, skb);
2971	}
2972
2973	if (!skb_shared(skb)) {
2974		/* Save full packet checksum */
2975		skb->csum = csum;
2976		skb->ip_summed = CHECKSUM_COMPLETE;
2977		skb->csum_complete_sw = 1;
2978		skb->csum_valid = !sum;
2979	}
2980
2981	return sum;
2982}
2983EXPORT_SYMBOL(__skb_checksum_complete);
2984
2985static __wsum warn_crc32c_csum_update(const void *buff, int len, __wsum sum)
2986{
2987	net_warn_ratelimited(
2988		"%s: attempt to compute crc32c without libcrc32c.ko\n",
2989		__func__);
2990	return 0;
2991}
2992
2993static __wsum warn_crc32c_csum_combine(__wsum csum, __wsum csum2,
2994				       int offset, int len)
2995{
2996	net_warn_ratelimited(
2997		"%s: attempt to compute crc32c without libcrc32c.ko\n",
2998		__func__);
2999	return 0;
3000}
3001
3002static const struct skb_checksum_ops default_crc32c_ops = {
3003	.update  = warn_crc32c_csum_update,
3004	.combine = warn_crc32c_csum_combine,
3005};
3006
3007const struct skb_checksum_ops *crc32c_csum_stub __read_mostly =
3008	&default_crc32c_ops;
3009EXPORT_SYMBOL(crc32c_csum_stub);
3010
3011 /**
3012 *	skb_zerocopy_headlen - Calculate headroom needed for skb_zerocopy()
3013 *	@from: source buffer
3014 *
3015 *	Calculates the amount of linear headroom needed in the 'to' skb passed
3016 *	into skb_zerocopy().
3017 */
3018unsigned int
3019skb_zerocopy_headlen(const struct sk_buff *from)
3020{
3021	unsigned int hlen = 0;
3022
3023	if (!from->head_frag ||
3024	    skb_headlen(from) < L1_CACHE_BYTES ||
3025	    skb_shinfo(from)->nr_frags >= MAX_SKB_FRAGS) {
3026		hlen = skb_headlen(from);
3027		if (!hlen)
3028			hlen = from->len;
3029	}
3030
3031	if (skb_has_frag_list(from))
3032		hlen = from->len;
3033
3034	return hlen;
3035}
3036EXPORT_SYMBOL_GPL(skb_zerocopy_headlen);
3037
3038/**
3039 *	skb_zerocopy - Zero copy skb to skb
3040 *	@to: destination buffer
3041 *	@from: source buffer
3042 *	@len: number of bytes to copy from source buffer
3043 *	@hlen: size of linear headroom in destination buffer
3044 *
3045 *	Copies up to `len` bytes from `from` to `to` by creating references
3046 *	to the frags in the source buffer.
3047 *
3048 *	The `hlen` as calculated by skb_zerocopy_headlen() specifies the
3049 *	headroom in the `to` buffer.
3050 *
3051 *	Return value:
3052 *	0: everything is OK
3053 *	-ENOMEM: couldn't orphan frags of @from due to lack of memory
3054 *	-EFAULT: skb_copy_bits() found some problem with skb geometry
3055 */
3056int
3057skb_zerocopy(struct sk_buff *to, struct sk_buff *from, int len, int hlen)
3058{
3059	int i, j = 0;
3060	int plen = 0; /* length of skb->head fragment */
3061	int ret;
3062	struct page *page;
3063	unsigned int offset;
3064
3065	BUG_ON(!from->head_frag && !hlen);
3066
3067	/* dont bother with small payloads */
3068	if (len <= skb_tailroom(to))
3069		return skb_copy_bits(from, 0, skb_put(to, len), len);
3070
3071	if (hlen) {
3072		ret = skb_copy_bits(from, 0, skb_put(to, hlen), hlen);
3073		if (unlikely(ret))
3074			return ret;
3075		len -= hlen;
3076	} else {
3077		plen = min_t(int, skb_headlen(from), len);
3078		if (plen) {
3079			page = virt_to_head_page(from->head);
3080			offset = from->data - (unsigned char *)page_address(page);
3081			__skb_fill_page_desc(to, 0, page, offset, plen);
3082			get_page(page);
3083			j = 1;
3084			len -= plen;
3085		}
3086	}
3087
3088	to->truesize += len + plen;
3089	to->len += len + plen;
3090	to->data_len += len + plen;
3091
3092	if (unlikely(skb_orphan_frags(from, GFP_ATOMIC))) {
3093		skb_tx_error(from);
3094		return -ENOMEM;
3095	}
3096	skb_zerocopy_clone(to, from, GFP_ATOMIC);
3097
3098	for (i = 0; i < skb_shinfo(from)->nr_frags; i++) {
3099		int size;
3100
3101		if (!len)
3102			break;
3103		skb_shinfo(to)->frags[j] = skb_shinfo(from)->frags[i];
3104		size = min_t(int, skb_frag_size(&skb_shinfo(to)->frags[j]),
3105					len);
3106		skb_frag_size_set(&skb_shinfo(to)->frags[j], size);
3107		len -= size;
3108		skb_frag_ref(to, j);
3109		j++;
3110	}
3111	skb_shinfo(to)->nr_frags = j;
3112
3113	return 0;
3114}
3115EXPORT_SYMBOL_GPL(skb_zerocopy);
3116
3117void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to)
3118{
3119	__wsum csum;
3120	long csstart;
3121
3122	if (skb->ip_summed == CHECKSUM_PARTIAL)
3123		csstart = skb_checksum_start_offset(skb);
3124	else
3125		csstart = skb_headlen(skb);
3126
3127	BUG_ON(csstart > skb_headlen(skb));
3128
3129	skb_copy_from_linear_data(skb, to, csstart);
3130
3131	csum = 0;
3132	if (csstart != skb->len)
3133		csum = skb_copy_and_csum_bits(skb, csstart, to + csstart,
3134					      skb->len - csstart);
3135
3136	if (skb->ip_summed == CHECKSUM_PARTIAL) {
3137		long csstuff = csstart + skb->csum_offset;
3138
3139		*((__sum16 *)(to + csstuff)) = csum_fold(csum);
3140	}
3141}
3142EXPORT_SYMBOL(skb_copy_and_csum_dev);
3143
3144/**
3145 *	skb_dequeue - remove from the head of the queue
3146 *	@list: list to dequeue from
3147 *
3148 *	Remove the head of the list. The list lock is taken so the function
3149 *	may be used safely with other locking list functions. The head item is
3150 *	returned or %NULL if the list is empty.
3151 */
3152
3153struct sk_buff *skb_dequeue(struct sk_buff_head *list)
3154{
3155	unsigned long flags;
3156	struct sk_buff *result;
3157
3158	spin_lock_irqsave(&list->lock, flags);
3159	result = __skb_dequeue(list);
3160	spin_unlock_irqrestore(&list->lock, flags);
3161	return result;
3162}
3163EXPORT_SYMBOL(skb_dequeue);
3164
3165/**
3166 *	skb_dequeue_tail - remove from the tail of the queue
3167 *	@list: list to dequeue from
3168 *
3169 *	Remove the tail of the list. The list lock is taken so the function
3170 *	may be used safely with other locking list functions. The tail item is
3171 *	returned or %NULL if the list is empty.
3172 */
3173struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list)
3174{
3175	unsigned long flags;
3176	struct sk_buff *result;
3177
3178	spin_lock_irqsave(&list->lock, flags);
3179	result = __skb_dequeue_tail(list);
3180	spin_unlock_irqrestore(&list->lock, flags);
3181	return result;
3182}
3183EXPORT_SYMBOL(skb_dequeue_tail);
3184
3185/**
3186 *	skb_queue_purge - empty a list
3187 *	@list: list to empty
3188 *
3189 *	Delete all buffers on an &sk_buff list. Each buffer is removed from
3190 *	the list and one reference dropped. This function takes the list
3191 *	lock and is atomic with respect to other list locking functions.
3192 */
3193void skb_queue_purge(struct sk_buff_head *list)
3194{
3195	struct sk_buff *skb;
3196	while ((skb = skb_dequeue(list)) != NULL)
3197		kfree_skb(skb);
3198}
3199EXPORT_SYMBOL(skb_queue_purge);
3200
3201/**
3202 *	skb_rbtree_purge - empty a skb rbtree
3203 *	@root: root of the rbtree to empty
3204 *	Return value: the sum of truesizes of all purged skbs.
3205 *
3206 *	Delete all buffers on an &sk_buff rbtree. Each buffer is removed from
3207 *	the list and one reference dropped. This function does not take
3208 *	any lock. Synchronization should be handled by the caller (e.g., TCP
3209 *	out-of-order queue is protected by the socket lock).
3210 */
3211unsigned int skb_rbtree_purge(struct rb_root *root)
3212{
3213	struct rb_node *p = rb_first(root);
3214	unsigned int sum = 0;
3215
3216	while (p) {
3217		struct sk_buff *skb = rb_entry(p, struct sk_buff, rbnode);
3218
3219		p = rb_next(p);
3220		rb_erase(&skb->rbnode, root);
3221		sum += skb->truesize;
3222		kfree_skb(skb);
3223	}
3224	return sum;
3225}
3226
3227/**
3228 *	skb_queue_head - queue a buffer at the list head
3229 *	@list: list to use
3230 *	@newsk: buffer to queue
3231 *
3232 *	Queue a buffer at the start of the list. This function takes the
3233 *	list lock and can be used safely with other locking &sk_buff functions
3234 *	safely.
3235 *
3236 *	A buffer cannot be placed on two lists at the same time.
3237 */
3238void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk)
3239{
3240	unsigned long flags;
3241
3242	spin_lock_irqsave(&list->lock, flags);
3243	__skb_queue_head(list, newsk);
3244	spin_unlock_irqrestore(&list->lock, flags);
3245}
3246EXPORT_SYMBOL(skb_queue_head);
3247
3248/**
3249 *	skb_queue_tail - queue a buffer at the list tail
3250 *	@list: list to use
3251 *	@newsk: buffer to queue
3252 *
3253 *	Queue a buffer at the tail of the list. This function takes the
3254 *	list lock and can be used safely with other locking &sk_buff functions
3255 *	safely.
3256 *
3257 *	A buffer cannot be placed on two lists at the same time.
3258 */
3259void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk)
3260{
3261	unsigned long flags;
3262
3263	spin_lock_irqsave(&list->lock, flags);
3264	__skb_queue_tail(list, newsk);
3265	spin_unlock_irqrestore(&list->lock, flags);
3266}
3267EXPORT_SYMBOL(skb_queue_tail);
3268
3269/**
3270 *	skb_unlink	-	remove a buffer from a list
3271 *	@skb: buffer to remove
3272 *	@list: list to use
3273 *
3274 *	Remove a packet from a list. The list locks are taken and this
3275 *	function is atomic with respect to other list locked calls
3276 *
3277 *	You must know what list the SKB is on.
3278 */
3279void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
3280{
3281	unsigned long flags;
3282
3283	spin_lock_irqsave(&list->lock, flags);
3284	__skb_unlink(skb, list);
3285	spin_unlock_irqrestore(&list->lock, flags);
3286}
3287EXPORT_SYMBOL(skb_unlink);
3288
3289/**
3290 *	skb_append	-	append a buffer
3291 *	@old: buffer to insert after
3292 *	@newsk: buffer to insert
3293 *	@list: list to use
3294 *
3295 *	Place a packet after a given packet in a list. The list locks are taken
3296 *	and this function is atomic with respect to other list locked calls.
3297 *	A buffer cannot be placed on two lists at the same time.
3298 */
3299void skb_append(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list)
3300{
3301	unsigned long flags;
3302
3303	spin_lock_irqsave(&list->lock, flags);
3304	__skb_queue_after(list, old, newsk);
3305	spin_unlock_irqrestore(&list->lock, flags);
3306}
3307EXPORT_SYMBOL(skb_append);
3308
3309static inline void skb_split_inside_header(struct sk_buff *skb,
3310					   struct sk_buff* skb1,
3311					   const u32 len, const int pos)
3312{
3313	int i;
3314
3315	skb_copy_from_linear_data_offset(skb, len, skb_put(skb1, pos - len),
3316					 pos - len);
3317	/* And move data appendix as is. */
3318	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
3319		skb_shinfo(skb1)->frags[i] = skb_shinfo(skb)->frags[i];
3320
3321	skb_shinfo(skb1)->nr_frags = skb_shinfo(skb)->nr_frags;
3322	skb_shinfo(skb)->nr_frags  = 0;
3323	skb1->data_len		   = skb->data_len;
3324	skb1->len		   += skb1->data_len;
3325	skb->data_len		   = 0;
3326	skb->len		   = len;
3327	skb_set_tail_pointer(skb, len);
3328}
3329
3330static inline void skb_split_no_header(struct sk_buff *skb,
3331				       struct sk_buff* skb1,
3332				       const u32 len, int pos)
3333{
3334	int i, k = 0;
3335	const int nfrags = skb_shinfo(skb)->nr_frags;
3336
3337	skb_shinfo(skb)->nr_frags = 0;
3338	skb1->len		  = skb1->data_len = skb->len - len;
3339	skb->len		  = len;
3340	skb->data_len		  = len - pos;
3341
3342	for (i = 0; i < nfrags; i++) {
3343		int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
3344
3345		if (pos + size > len) {
3346			skb_shinfo(skb1)->frags[k] = skb_shinfo(skb)->frags[i];
3347
3348			if (pos < len) {
3349				/* Split frag.
3350				 * We have two variants in this case:
3351				 * 1. Move all the frag to the second
3352				 *    part, if it is possible. F.e.
3353				 *    this approach is mandatory for TUX,
3354				 *    where splitting is expensive.
3355				 * 2. Split is accurately. We make this.
3356				 */
3357				skb_frag_ref(skb, i);
3358				skb_frag_off_add(&skb_shinfo(skb1)->frags[0], len - pos);
3359				skb_frag_size_sub(&skb_shinfo(skb1)->frags[0], len - pos);
3360				skb_frag_size_set(&skb_shinfo(skb)->frags[i], len - pos);
3361				skb_shinfo(skb)->nr_frags++;
3362			}
3363			k++;
3364		} else
3365			skb_shinfo(skb)->nr_frags++;
3366		pos += size;
3367	}
3368	skb_shinfo(skb1)->nr_frags = k;
3369}
3370
3371/**
3372 * skb_split - Split fragmented skb to two parts at length len.
3373 * @skb: the buffer to split
3374 * @skb1: the buffer to receive the second part
3375 * @len: new length for skb
3376 */
3377void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len)
3378{
3379	int pos = skb_headlen(skb);
3380
3381	skb_shinfo(skb1)->flags |= skb_shinfo(skb)->flags & SKBFL_SHARED_FRAG;
 
3382	skb_zerocopy_clone(skb1, skb, 0);
3383	if (len < pos)	/* Split line is inside header. */
3384		skb_split_inside_header(skb, skb1, len, pos);
3385	else		/* Second chunk has no header, nothing to copy. */
3386		skb_split_no_header(skb, skb1, len, pos);
3387}
3388EXPORT_SYMBOL(skb_split);
3389
3390/* Shifting from/to a cloned skb is a no-go.
3391 *
3392 * Caller cannot keep skb_shinfo related pointers past calling here!
3393 */
3394static int skb_prepare_for_shift(struct sk_buff *skb)
3395{
3396	int ret = 0;
3397
3398	if (skb_cloned(skb)) {
3399		/* Save and restore truesize: pskb_expand_head() may reallocate
3400		 * memory where ksize(kmalloc(S)) != ksize(kmalloc(S)), but we
3401		 * cannot change truesize at this point.
3402		 */
3403		unsigned int save_truesize = skb->truesize;
3404
3405		ret = pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
3406		skb->truesize = save_truesize;
3407	}
3408	return ret;
3409}
3410
3411/**
3412 * skb_shift - Shifts paged data partially from skb to another
3413 * @tgt: buffer into which tail data gets added
3414 * @skb: buffer from which the paged data comes from
3415 * @shiftlen: shift up to this many bytes
3416 *
3417 * Attempts to shift up to shiftlen worth of bytes, which may be less than
3418 * the length of the skb, from skb to tgt. Returns number bytes shifted.
3419 * It's up to caller to free skb if everything was shifted.
3420 *
3421 * If @tgt runs out of frags, the whole operation is aborted.
3422 *
3423 * Skb cannot include anything else but paged data while tgt is allowed
3424 * to have non-paged data as well.
3425 *
3426 * TODO: full sized shift could be optimized but that would need
3427 * specialized skb free'er to handle frags without up-to-date nr_frags.
3428 */
3429int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen)
3430{
3431	int from, to, merge, todo;
3432	skb_frag_t *fragfrom, *fragto;
3433
3434	BUG_ON(shiftlen > skb->len);
3435
3436	if (skb_headlen(skb))
3437		return 0;
3438	if (skb_zcopy(tgt) || skb_zcopy(skb))
3439		return 0;
3440
3441	todo = shiftlen;
3442	from = 0;
3443	to = skb_shinfo(tgt)->nr_frags;
3444	fragfrom = &skb_shinfo(skb)->frags[from];
3445
3446	/* Actual merge is delayed until the point when we know we can
3447	 * commit all, so that we don't have to undo partial changes
3448	 */
3449	if (!to ||
3450	    !skb_can_coalesce(tgt, to, skb_frag_page(fragfrom),
3451			      skb_frag_off(fragfrom))) {
3452		merge = -1;
3453	} else {
3454		merge = to - 1;
3455
3456		todo -= skb_frag_size(fragfrom);
3457		if (todo < 0) {
3458			if (skb_prepare_for_shift(skb) ||
3459			    skb_prepare_for_shift(tgt))
3460				return 0;
3461
3462			/* All previous frag pointers might be stale! */
3463			fragfrom = &skb_shinfo(skb)->frags[from];
3464			fragto = &skb_shinfo(tgt)->frags[merge];
3465
3466			skb_frag_size_add(fragto, shiftlen);
3467			skb_frag_size_sub(fragfrom, shiftlen);
3468			skb_frag_off_add(fragfrom, shiftlen);
3469
3470			goto onlymerged;
3471		}
3472
3473		from++;
3474	}
3475
3476	/* Skip full, not-fitting skb to avoid expensive operations */
3477	if ((shiftlen == skb->len) &&
3478	    (skb_shinfo(skb)->nr_frags - from) > (MAX_SKB_FRAGS - to))
3479		return 0;
3480
3481	if (skb_prepare_for_shift(skb) || skb_prepare_for_shift(tgt))
3482		return 0;
3483
3484	while ((todo > 0) && (from < skb_shinfo(skb)->nr_frags)) {
3485		if (to == MAX_SKB_FRAGS)
3486			return 0;
3487
3488		fragfrom = &skb_shinfo(skb)->frags[from];
3489		fragto = &skb_shinfo(tgt)->frags[to];
3490
3491		if (todo >= skb_frag_size(fragfrom)) {
3492			*fragto = *fragfrom;
3493			todo -= skb_frag_size(fragfrom);
3494			from++;
3495			to++;
3496
3497		} else {
3498			__skb_frag_ref(fragfrom);
3499			skb_frag_page_copy(fragto, fragfrom);
3500			skb_frag_off_copy(fragto, fragfrom);
3501			skb_frag_size_set(fragto, todo);
3502
3503			skb_frag_off_add(fragfrom, todo);
3504			skb_frag_size_sub(fragfrom, todo);
3505			todo = 0;
3506
3507			to++;
3508			break;
3509		}
3510	}
3511
3512	/* Ready to "commit" this state change to tgt */
3513	skb_shinfo(tgt)->nr_frags = to;
3514
3515	if (merge >= 0) {
3516		fragfrom = &skb_shinfo(skb)->frags[0];
3517		fragto = &skb_shinfo(tgt)->frags[merge];
3518
3519		skb_frag_size_add(fragto, skb_frag_size(fragfrom));
3520		__skb_frag_unref(fragfrom, skb->pp_recycle);
3521	}
3522
3523	/* Reposition in the original skb */
3524	to = 0;
3525	while (from < skb_shinfo(skb)->nr_frags)
3526		skb_shinfo(skb)->frags[to++] = skb_shinfo(skb)->frags[from++];
3527	skb_shinfo(skb)->nr_frags = to;
3528
3529	BUG_ON(todo > 0 && !skb_shinfo(skb)->nr_frags);
3530
3531onlymerged:
3532	/* Most likely the tgt won't ever need its checksum anymore, skb on
3533	 * the other hand might need it if it needs to be resent
3534	 */
3535	tgt->ip_summed = CHECKSUM_PARTIAL;
3536	skb->ip_summed = CHECKSUM_PARTIAL;
3537
3538	/* Yak, is it really working this way? Some helper please? */
3539	skb->len -= shiftlen;
3540	skb->data_len -= shiftlen;
3541	skb->truesize -= shiftlen;
3542	tgt->len += shiftlen;
3543	tgt->data_len += shiftlen;
3544	tgt->truesize += shiftlen;
3545
3546	return shiftlen;
3547}
3548
3549/**
3550 * skb_prepare_seq_read - Prepare a sequential read of skb data
3551 * @skb: the buffer to read
3552 * @from: lower offset of data to be read
3553 * @to: upper offset of data to be read
3554 * @st: state variable
3555 *
3556 * Initializes the specified state variable. Must be called before
3557 * invoking skb_seq_read() for the first time.
3558 */
3559void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from,
3560			  unsigned int to, struct skb_seq_state *st)
3561{
3562	st->lower_offset = from;
3563	st->upper_offset = to;
3564	st->root_skb = st->cur_skb = skb;
3565	st->frag_idx = st->stepped_offset = 0;
3566	st->frag_data = NULL;
3567	st->frag_off = 0;
3568}
3569EXPORT_SYMBOL(skb_prepare_seq_read);
3570
3571/**
3572 * skb_seq_read - Sequentially read skb data
3573 * @consumed: number of bytes consumed by the caller so far
3574 * @data: destination pointer for data to be returned
3575 * @st: state variable
3576 *
3577 * Reads a block of skb data at @consumed relative to the
3578 * lower offset specified to skb_prepare_seq_read(). Assigns
3579 * the head of the data block to @data and returns the length
3580 * of the block or 0 if the end of the skb data or the upper
3581 * offset has been reached.
3582 *
3583 * The caller is not required to consume all of the data
3584 * returned, i.e. @consumed is typically set to the number
3585 * of bytes already consumed and the next call to
3586 * skb_seq_read() will return the remaining part of the block.
3587 *
3588 * Note 1: The size of each block of data returned can be arbitrary,
3589 *       this limitation is the cost for zerocopy sequential
3590 *       reads of potentially non linear data.
3591 *
3592 * Note 2: Fragment lists within fragments are not implemented
3593 *       at the moment, state->root_skb could be replaced with
3594 *       a stack for this purpose.
3595 */
3596unsigned int skb_seq_read(unsigned int consumed, const u8 **data,
3597			  struct skb_seq_state *st)
3598{
3599	unsigned int block_limit, abs_offset = consumed + st->lower_offset;
3600	skb_frag_t *frag;
3601
3602	if (unlikely(abs_offset >= st->upper_offset)) {
3603		if (st->frag_data) {
3604			kunmap_atomic(st->frag_data);
3605			st->frag_data = NULL;
3606		}
3607		return 0;
3608	}
3609
3610next_skb:
3611	block_limit = skb_headlen(st->cur_skb) + st->stepped_offset;
3612
3613	if (abs_offset < block_limit && !st->frag_data) {
3614		*data = st->cur_skb->data + (abs_offset - st->stepped_offset);
3615		return block_limit - abs_offset;
3616	}
3617
3618	if (st->frag_idx == 0 && !st->frag_data)
3619		st->stepped_offset += skb_headlen(st->cur_skb);
3620
3621	while (st->frag_idx < skb_shinfo(st->cur_skb)->nr_frags) {
3622		unsigned int pg_idx, pg_off, pg_sz;
3623
3624		frag = &skb_shinfo(st->cur_skb)->frags[st->frag_idx];
 
3625
3626		pg_idx = 0;
3627		pg_off = skb_frag_off(frag);
3628		pg_sz = skb_frag_size(frag);
3629
3630		if (skb_frag_must_loop(skb_frag_page(frag))) {
3631			pg_idx = (pg_off + st->frag_off) >> PAGE_SHIFT;
3632			pg_off = offset_in_page(pg_off + st->frag_off);
3633			pg_sz = min_t(unsigned int, pg_sz - st->frag_off,
3634						    PAGE_SIZE - pg_off);
3635		}
3636
3637		block_limit = pg_sz + st->stepped_offset;
3638		if (abs_offset < block_limit) {
3639			if (!st->frag_data)
3640				st->frag_data = kmap_atomic(skb_frag_page(frag) + pg_idx);
3641
3642			*data = (u8 *)st->frag_data + pg_off +
3643				(abs_offset - st->stepped_offset);
3644
3645			return block_limit - abs_offset;
3646		}
3647
3648		if (st->frag_data) {
3649			kunmap_atomic(st->frag_data);
3650			st->frag_data = NULL;
3651		}
3652
3653		st->stepped_offset += pg_sz;
3654		st->frag_off += pg_sz;
3655		if (st->frag_off == skb_frag_size(frag)) {
3656			st->frag_off = 0;
3657			st->frag_idx++;
3658		}
3659	}
3660
3661	if (st->frag_data) {
3662		kunmap_atomic(st->frag_data);
3663		st->frag_data = NULL;
3664	}
3665
3666	if (st->root_skb == st->cur_skb && skb_has_frag_list(st->root_skb)) {
3667		st->cur_skb = skb_shinfo(st->root_skb)->frag_list;
3668		st->frag_idx = 0;
3669		goto next_skb;
3670	} else if (st->cur_skb->next) {
3671		st->cur_skb = st->cur_skb->next;
3672		st->frag_idx = 0;
3673		goto next_skb;
3674	}
3675
3676	return 0;
3677}
3678EXPORT_SYMBOL(skb_seq_read);
3679
3680/**
3681 * skb_abort_seq_read - Abort a sequential read of skb data
3682 * @st: state variable
3683 *
3684 * Must be called if skb_seq_read() was not called until it
3685 * returned 0.
3686 */
3687void skb_abort_seq_read(struct skb_seq_state *st)
3688{
3689	if (st->frag_data)
3690		kunmap_atomic(st->frag_data);
3691}
3692EXPORT_SYMBOL(skb_abort_seq_read);
3693
3694#define TS_SKB_CB(state)	((struct skb_seq_state *) &((state)->cb))
3695
3696static unsigned int skb_ts_get_next_block(unsigned int offset, const u8 **text,
3697					  struct ts_config *conf,
3698					  struct ts_state *state)
3699{
3700	return skb_seq_read(offset, text, TS_SKB_CB(state));
3701}
3702
3703static void skb_ts_finish(struct ts_config *conf, struct ts_state *state)
3704{
3705	skb_abort_seq_read(TS_SKB_CB(state));
3706}
3707
3708/**
3709 * skb_find_text - Find a text pattern in skb data
3710 * @skb: the buffer to look in
3711 * @from: search offset
3712 * @to: search limit
3713 * @config: textsearch configuration
3714 *
3715 * Finds a pattern in the skb data according to the specified
3716 * textsearch configuration. Use textsearch_next() to retrieve
3717 * subsequent occurrences of the pattern. Returns the offset
3718 * to the first occurrence or UINT_MAX if no match was found.
3719 */
3720unsigned int skb_find_text(struct sk_buff *skb, unsigned int from,
3721			   unsigned int to, struct ts_config *config)
3722{
3723	struct ts_state state;
3724	unsigned int ret;
3725
3726	BUILD_BUG_ON(sizeof(struct skb_seq_state) > sizeof(state.cb));
3727
3728	config->get_next_block = skb_ts_get_next_block;
3729	config->finish = skb_ts_finish;
3730
3731	skb_prepare_seq_read(skb, from, to, TS_SKB_CB(&state));
3732
3733	ret = textsearch_find(config, &state);
3734	return (ret <= to - from ? ret : UINT_MAX);
3735}
3736EXPORT_SYMBOL(skb_find_text);
3737
3738int skb_append_pagefrags(struct sk_buff *skb, struct page *page,
3739			 int offset, size_t size)
3740{
3741	int i = skb_shinfo(skb)->nr_frags;
3742
3743	if (skb_can_coalesce(skb, i, page, offset)) {
3744		skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], size);
3745	} else if (i < MAX_SKB_FRAGS) {
3746		get_page(page);
3747		skb_fill_page_desc(skb, i, page, offset, size);
3748	} else {
3749		return -EMSGSIZE;
3750	}
3751
3752	return 0;
3753}
3754EXPORT_SYMBOL_GPL(skb_append_pagefrags);
3755
3756/**
3757 *	skb_pull_rcsum - pull skb and update receive checksum
3758 *	@skb: buffer to update
3759 *	@len: length of data pulled
3760 *
3761 *	This function performs an skb_pull on the packet and updates
3762 *	the CHECKSUM_COMPLETE checksum.  It should be used on
3763 *	receive path processing instead of skb_pull unless you know
3764 *	that the checksum difference is zero (e.g., a valid IP header)
3765 *	or you are setting ip_summed to CHECKSUM_NONE.
3766 */
3767void *skb_pull_rcsum(struct sk_buff *skb, unsigned int len)
3768{
3769	unsigned char *data = skb->data;
3770
3771	BUG_ON(len > skb->len);
3772	__skb_pull(skb, len);
3773	skb_postpull_rcsum(skb, data, len);
3774	return skb->data;
3775}
3776EXPORT_SYMBOL_GPL(skb_pull_rcsum);
3777
3778static inline skb_frag_t skb_head_frag_to_page_desc(struct sk_buff *frag_skb)
3779{
3780	skb_frag_t head_frag;
3781	struct page *page;
3782
3783	page = virt_to_head_page(frag_skb->head);
3784	__skb_frag_set_page(&head_frag, page);
3785	skb_frag_off_set(&head_frag, frag_skb->data -
3786			 (unsigned char *)page_address(page));
3787	skb_frag_size_set(&head_frag, skb_headlen(frag_skb));
3788	return head_frag;
3789}
3790
3791struct sk_buff *skb_segment_list(struct sk_buff *skb,
3792				 netdev_features_t features,
3793				 unsigned int offset)
3794{
3795	struct sk_buff *list_skb = skb_shinfo(skb)->frag_list;
3796	unsigned int tnl_hlen = skb_tnl_header_len(skb);
3797	unsigned int delta_truesize = 0;
3798	unsigned int delta_len = 0;
3799	struct sk_buff *tail = NULL;
3800	struct sk_buff *nskb, *tmp;
3801	int err;
3802
3803	skb_push(skb, -skb_network_offset(skb) + offset);
3804
3805	skb_shinfo(skb)->frag_list = NULL;
3806
3807	do {
3808		nskb = list_skb;
3809		list_skb = list_skb->next;
3810
3811		err = 0;
3812		if (skb_shared(nskb)) {
3813			tmp = skb_clone(nskb, GFP_ATOMIC);
3814			if (tmp) {
3815				consume_skb(nskb);
3816				nskb = tmp;
3817				err = skb_unclone(nskb, GFP_ATOMIC);
3818			} else {
3819				err = -ENOMEM;
3820			}
3821		}
3822
3823		if (!tail)
3824			skb->next = nskb;
3825		else
3826			tail->next = nskb;
3827
3828		if (unlikely(err)) {
3829			nskb->next = list_skb;
3830			goto err_linearize;
3831		}
3832
3833		tail = nskb;
3834
3835		delta_len += nskb->len;
3836		delta_truesize += nskb->truesize;
3837
3838		skb_push(nskb, -skb_network_offset(nskb) + offset);
3839
3840		skb_release_head_state(nskb);
3841		 __copy_skb_header(nskb, skb);
3842
3843		skb_headers_offset_update(nskb, skb_headroom(nskb) - skb_headroom(skb));
3844		skb_copy_from_linear_data_offset(skb, -tnl_hlen,
3845						 nskb->data - tnl_hlen,
3846						 offset + tnl_hlen);
3847
3848		if (skb_needs_linearize(nskb, features) &&
3849		    __skb_linearize(nskb))
3850			goto err_linearize;
3851
3852	} while (list_skb);
3853
3854	skb->truesize = skb->truesize - delta_truesize;
3855	skb->data_len = skb->data_len - delta_len;
3856	skb->len = skb->len - delta_len;
3857
3858	skb_gso_reset(skb);
3859
3860	skb->prev = tail;
3861
3862	if (skb_needs_linearize(skb, features) &&
3863	    __skb_linearize(skb))
3864		goto err_linearize;
3865
3866	skb_get(skb);
3867
3868	return skb;
3869
3870err_linearize:
3871	kfree_skb_list(skb->next);
3872	skb->next = NULL;
3873	return ERR_PTR(-ENOMEM);
3874}
3875EXPORT_SYMBOL_GPL(skb_segment_list);
3876
3877int skb_gro_receive_list(struct sk_buff *p, struct sk_buff *skb)
3878{
3879	if (unlikely(p->len + skb->len >= 65536))
3880		return -E2BIG;
3881
3882	if (NAPI_GRO_CB(p)->last == p)
3883		skb_shinfo(p)->frag_list = skb;
3884	else
3885		NAPI_GRO_CB(p)->last->next = skb;
3886
3887	skb_pull(skb, skb_gro_offset(skb));
3888
3889	NAPI_GRO_CB(p)->last = skb;
3890	NAPI_GRO_CB(p)->count++;
3891	p->data_len += skb->len;
3892	p->truesize += skb->truesize;
3893	p->len += skb->len;
3894
3895	NAPI_GRO_CB(skb)->same_flow = 1;
3896
3897	return 0;
3898}
3899
3900/**
3901 *	skb_segment - Perform protocol segmentation on skb.
3902 *	@head_skb: buffer to segment
3903 *	@features: features for the output path (see dev->features)
3904 *
3905 *	This function performs segmentation on the given skb.  It returns
3906 *	a pointer to the first in a list of new skbs for the segments.
3907 *	In case of error it returns ERR_PTR(err).
3908 */
3909struct sk_buff *skb_segment(struct sk_buff *head_skb,
3910			    netdev_features_t features)
3911{
3912	struct sk_buff *segs = NULL;
3913	struct sk_buff *tail = NULL;
3914	struct sk_buff *list_skb = skb_shinfo(head_skb)->frag_list;
3915	skb_frag_t *frag = skb_shinfo(head_skb)->frags;
3916	unsigned int mss = skb_shinfo(head_skb)->gso_size;
3917	unsigned int doffset = head_skb->data - skb_mac_header(head_skb);
3918	struct sk_buff *frag_skb = head_skb;
3919	unsigned int offset = doffset;
3920	unsigned int tnl_hlen = skb_tnl_header_len(head_skb);
3921	unsigned int partial_segs = 0;
3922	unsigned int headroom;
3923	unsigned int len = head_skb->len;
3924	__be16 proto;
3925	bool csum, sg;
3926	int nfrags = skb_shinfo(head_skb)->nr_frags;
3927	int err = -ENOMEM;
3928	int i = 0;
3929	int pos;
3930
3931	if (list_skb && !list_skb->head_frag && skb_headlen(list_skb) &&
3932	    (skb_shinfo(head_skb)->gso_type & SKB_GSO_DODGY)) {
3933		/* gso_size is untrusted, and we have a frag_list with a linear
3934		 * non head_frag head.
3935		 *
3936		 * (we assume checking the first list_skb member suffices;
3937		 * i.e if either of the list_skb members have non head_frag
3938		 * head, then the first one has too).
3939		 *
3940		 * If head_skb's headlen does not fit requested gso_size, it
3941		 * means that the frag_list members do NOT terminate on exact
3942		 * gso_size boundaries. Hence we cannot perform skb_frag_t page
3943		 * sharing. Therefore we must fallback to copying the frag_list
3944		 * skbs; we do so by disabling SG.
3945		 */
3946		if (mss != GSO_BY_FRAGS && mss != skb_headlen(head_skb))
3947			features &= ~NETIF_F_SG;
3948	}
3949
3950	__skb_push(head_skb, doffset);
3951	proto = skb_network_protocol(head_skb, NULL);
3952	if (unlikely(!proto))
3953		return ERR_PTR(-EINVAL);
3954
3955	sg = !!(features & NETIF_F_SG);
3956	csum = !!can_checksum_protocol(features, proto);
3957
3958	if (sg && csum && (mss != GSO_BY_FRAGS))  {
3959		if (!(features & NETIF_F_GSO_PARTIAL)) {
3960			struct sk_buff *iter;
3961			unsigned int frag_len;
3962
3963			if (!list_skb ||
3964			    !net_gso_ok(features, skb_shinfo(head_skb)->gso_type))
3965				goto normal;
3966
3967			/* If we get here then all the required
3968			 * GSO features except frag_list are supported.
3969			 * Try to split the SKB to multiple GSO SKBs
3970			 * with no frag_list.
3971			 * Currently we can do that only when the buffers don't
3972			 * have a linear part and all the buffers except
3973			 * the last are of the same length.
3974			 */
3975			frag_len = list_skb->len;
3976			skb_walk_frags(head_skb, iter) {
3977				if (frag_len != iter->len && iter->next)
3978					goto normal;
3979				if (skb_headlen(iter) && !iter->head_frag)
3980					goto normal;
3981
3982				len -= iter->len;
3983			}
3984
3985			if (len != frag_len)
3986				goto normal;
3987		}
3988
3989		/* GSO partial only requires that we trim off any excess that
3990		 * doesn't fit into an MSS sized block, so take care of that
3991		 * now.
3992		 */
3993		partial_segs = len / mss;
3994		if (partial_segs > 1)
3995			mss *= partial_segs;
3996		else
3997			partial_segs = 0;
3998	}
3999
4000normal:
4001	headroom = skb_headroom(head_skb);
4002	pos = skb_headlen(head_skb);
4003
4004	do {
4005		struct sk_buff *nskb;
4006		skb_frag_t *nskb_frag;
4007		int hsize;
4008		int size;
4009
4010		if (unlikely(mss == GSO_BY_FRAGS)) {
4011			len = list_skb->len;
4012		} else {
4013			len = head_skb->len - offset;
4014			if (len > mss)
4015				len = mss;
4016		}
4017
4018		hsize = skb_headlen(head_skb) - offset;
 
 
 
 
4019
4020		if (hsize <= 0 && i >= nfrags && skb_headlen(list_skb) &&
4021		    (skb_headlen(list_skb) == len || sg)) {
4022			BUG_ON(skb_headlen(list_skb) > len);
4023
4024			i = 0;
4025			nfrags = skb_shinfo(list_skb)->nr_frags;
4026			frag = skb_shinfo(list_skb)->frags;
4027			frag_skb = list_skb;
4028			pos += skb_headlen(list_skb);
4029
4030			while (pos < offset + len) {
4031				BUG_ON(i >= nfrags);
4032
4033				size = skb_frag_size(frag);
4034				if (pos + size > offset + len)
4035					break;
4036
4037				i++;
4038				pos += size;
4039				frag++;
4040			}
4041
4042			nskb = skb_clone(list_skb, GFP_ATOMIC);
4043			list_skb = list_skb->next;
4044
4045			if (unlikely(!nskb))
4046				goto err;
4047
4048			if (unlikely(pskb_trim(nskb, len))) {
4049				kfree_skb(nskb);
4050				goto err;
4051			}
4052
4053			hsize = skb_end_offset(nskb);
4054			if (skb_cow_head(nskb, doffset + headroom)) {
4055				kfree_skb(nskb);
4056				goto err;
4057			}
4058
4059			nskb->truesize += skb_end_offset(nskb) - hsize;
4060			skb_release_head_state(nskb);
4061			__skb_push(nskb, doffset);
4062		} else {
4063			if (hsize < 0)
4064				hsize = 0;
4065			if (hsize > len || !sg)
4066				hsize = len;
4067
4068			nskb = __alloc_skb(hsize + doffset + headroom,
4069					   GFP_ATOMIC, skb_alloc_rx_flag(head_skb),
4070					   NUMA_NO_NODE);
4071
4072			if (unlikely(!nskb))
4073				goto err;
4074
4075			skb_reserve(nskb, headroom);
4076			__skb_put(nskb, doffset);
4077		}
4078
4079		if (segs)
4080			tail->next = nskb;
4081		else
4082			segs = nskb;
4083		tail = nskb;
4084
4085		__copy_skb_header(nskb, head_skb);
4086
4087		skb_headers_offset_update(nskb, skb_headroom(nskb) - headroom);
4088		skb_reset_mac_len(nskb);
4089
4090		skb_copy_from_linear_data_offset(head_skb, -tnl_hlen,
4091						 nskb->data - tnl_hlen,
4092						 doffset + tnl_hlen);
4093
4094		if (nskb->len == len + doffset)
4095			goto perform_csum_check;
4096
4097		if (!sg) {
4098			if (!csum) {
4099				if (!nskb->remcsum_offload)
4100					nskb->ip_summed = CHECKSUM_NONE;
4101				SKB_GSO_CB(nskb)->csum =
4102					skb_copy_and_csum_bits(head_skb, offset,
4103							       skb_put(nskb,
4104								       len),
4105							       len);
4106				SKB_GSO_CB(nskb)->csum_start =
4107					skb_headroom(nskb) + doffset;
4108			} else {
4109				skb_copy_bits(head_skb, offset,
4110					      skb_put(nskb, len),
4111					      len);
4112			}
4113			continue;
4114		}
4115
4116		nskb_frag = skb_shinfo(nskb)->frags;
4117
4118		skb_copy_from_linear_data_offset(head_skb, offset,
4119						 skb_put(nskb, hsize), hsize);
4120
4121		skb_shinfo(nskb)->flags |= skb_shinfo(head_skb)->flags &
4122					   SKBFL_SHARED_FRAG;
4123
4124		if (skb_orphan_frags(frag_skb, GFP_ATOMIC) ||
4125		    skb_zerocopy_clone(nskb, frag_skb, GFP_ATOMIC))
4126			goto err;
4127
4128		while (pos < offset + len) {
4129			if (i >= nfrags) {
4130				i = 0;
4131				nfrags = skb_shinfo(list_skb)->nr_frags;
4132				frag = skb_shinfo(list_skb)->frags;
4133				frag_skb = list_skb;
4134				if (!skb_headlen(list_skb)) {
4135					BUG_ON(!nfrags);
4136				} else {
4137					BUG_ON(!list_skb->head_frag);
4138
4139					/* to make room for head_frag. */
4140					i--;
4141					frag--;
4142				}
4143				if (skb_orphan_frags(frag_skb, GFP_ATOMIC) ||
4144				    skb_zerocopy_clone(nskb, frag_skb,
4145						       GFP_ATOMIC))
4146					goto err;
4147
4148				list_skb = list_skb->next;
4149			}
4150
4151			if (unlikely(skb_shinfo(nskb)->nr_frags >=
4152				     MAX_SKB_FRAGS)) {
4153				net_warn_ratelimited(
4154					"skb_segment: too many frags: %u %u\n",
4155					pos, mss);
4156				err = -EINVAL;
4157				goto err;
4158			}
4159
4160			*nskb_frag = (i < 0) ? skb_head_frag_to_page_desc(frag_skb) : *frag;
4161			__skb_frag_ref(nskb_frag);
4162			size = skb_frag_size(nskb_frag);
4163
4164			if (pos < offset) {
4165				skb_frag_off_add(nskb_frag, offset - pos);
4166				skb_frag_size_sub(nskb_frag, offset - pos);
4167			}
4168
4169			skb_shinfo(nskb)->nr_frags++;
4170
4171			if (pos + size <= offset + len) {
4172				i++;
4173				frag++;
4174				pos += size;
4175			} else {
4176				skb_frag_size_sub(nskb_frag, pos + size - (offset + len));
4177				goto skip_fraglist;
4178			}
4179
4180			nskb_frag++;
4181		}
4182
4183skip_fraglist:
4184		nskb->data_len = len - hsize;
4185		nskb->len += nskb->data_len;
4186		nskb->truesize += nskb->data_len;
4187
4188perform_csum_check:
4189		if (!csum) {
4190			if (skb_has_shared_frag(nskb) &&
4191			    __skb_linearize(nskb))
4192				goto err;
4193
4194			if (!nskb->remcsum_offload)
4195				nskb->ip_summed = CHECKSUM_NONE;
4196			SKB_GSO_CB(nskb)->csum =
4197				skb_checksum(nskb, doffset,
4198					     nskb->len - doffset, 0);
4199			SKB_GSO_CB(nskb)->csum_start =
4200				skb_headroom(nskb) + doffset;
4201		}
4202	} while ((offset += len) < head_skb->len);
4203
4204	/* Some callers want to get the end of the list.
4205	 * Put it in segs->prev to avoid walking the list.
4206	 * (see validate_xmit_skb_list() for example)
4207	 */
4208	segs->prev = tail;
4209
4210	if (partial_segs) {
4211		struct sk_buff *iter;
4212		int type = skb_shinfo(head_skb)->gso_type;
4213		unsigned short gso_size = skb_shinfo(head_skb)->gso_size;
4214
4215		/* Update type to add partial and then remove dodgy if set */
4216		type |= (features & NETIF_F_GSO_PARTIAL) / NETIF_F_GSO_PARTIAL * SKB_GSO_PARTIAL;
4217		type &= ~SKB_GSO_DODGY;
4218
4219		/* Update GSO info and prepare to start updating headers on
4220		 * our way back down the stack of protocols.
4221		 */
4222		for (iter = segs; iter; iter = iter->next) {
4223			skb_shinfo(iter)->gso_size = gso_size;
4224			skb_shinfo(iter)->gso_segs = partial_segs;
4225			skb_shinfo(iter)->gso_type = type;
4226			SKB_GSO_CB(iter)->data_offset = skb_headroom(iter) + doffset;
4227		}
4228
4229		if (tail->len - doffset <= gso_size)
4230			skb_shinfo(tail)->gso_size = 0;
4231		else if (tail != segs)
4232			skb_shinfo(tail)->gso_segs = DIV_ROUND_UP(tail->len - doffset, gso_size);
4233	}
4234
4235	/* Following permits correct backpressure, for protocols
4236	 * using skb_set_owner_w().
4237	 * Idea is to tranfert ownership from head_skb to last segment.
4238	 */
4239	if (head_skb->destructor == sock_wfree) {
4240		swap(tail->truesize, head_skb->truesize);
4241		swap(tail->destructor, head_skb->destructor);
4242		swap(tail->sk, head_skb->sk);
4243	}
4244	return segs;
4245
4246err:
4247	kfree_skb_list(segs);
4248	return ERR_PTR(err);
4249}
4250EXPORT_SYMBOL_GPL(skb_segment);
4251
4252int skb_gro_receive(struct sk_buff *p, struct sk_buff *skb)
4253{
4254	struct skb_shared_info *pinfo, *skbinfo = skb_shinfo(skb);
4255	unsigned int offset = skb_gro_offset(skb);
4256	unsigned int headlen = skb_headlen(skb);
4257	unsigned int len = skb_gro_len(skb);
4258	unsigned int delta_truesize;
4259	struct sk_buff *lp;
4260
4261	if (unlikely(p->len + len >= 65536 || NAPI_GRO_CB(skb)->flush))
4262		return -E2BIG;
4263
4264	lp = NAPI_GRO_CB(p)->last;
4265	pinfo = skb_shinfo(lp);
4266
4267	if (headlen <= offset) {
4268		skb_frag_t *frag;
4269		skb_frag_t *frag2;
4270		int i = skbinfo->nr_frags;
4271		int nr_frags = pinfo->nr_frags + i;
4272
4273		if (nr_frags > MAX_SKB_FRAGS)
4274			goto merge;
4275
4276		offset -= headlen;
4277		pinfo->nr_frags = nr_frags;
4278		skbinfo->nr_frags = 0;
4279
4280		frag = pinfo->frags + nr_frags;
4281		frag2 = skbinfo->frags + i;
4282		do {
4283			*--frag = *--frag2;
4284		} while (--i);
4285
4286		skb_frag_off_add(frag, offset);
4287		skb_frag_size_sub(frag, offset);
4288
4289		/* all fragments truesize : remove (head size + sk_buff) */
4290		delta_truesize = skb->truesize -
4291				 SKB_TRUESIZE(skb_end_offset(skb));
4292
4293		skb->truesize -= skb->data_len;
4294		skb->len -= skb->data_len;
4295		skb->data_len = 0;
4296
4297		NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE;
4298		goto done;
4299	} else if (skb->head_frag) {
4300		int nr_frags = pinfo->nr_frags;
4301		skb_frag_t *frag = pinfo->frags + nr_frags;
4302		struct page *page = virt_to_head_page(skb->head);
4303		unsigned int first_size = headlen - offset;
4304		unsigned int first_offset;
4305
4306		if (nr_frags + 1 + skbinfo->nr_frags > MAX_SKB_FRAGS)
4307			goto merge;
4308
4309		first_offset = skb->data -
4310			       (unsigned char *)page_address(page) +
4311			       offset;
4312
4313		pinfo->nr_frags = nr_frags + 1 + skbinfo->nr_frags;
4314
4315		__skb_frag_set_page(frag, page);
4316		skb_frag_off_set(frag, first_offset);
4317		skb_frag_size_set(frag, first_size);
4318
4319		memcpy(frag + 1, skbinfo->frags, sizeof(*frag) * skbinfo->nr_frags);
4320		/* We dont need to clear skbinfo->nr_frags here */
4321
4322		delta_truesize = skb->truesize - SKB_DATA_ALIGN(sizeof(struct sk_buff));
4323		NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE_STOLEN_HEAD;
4324		goto done;
4325	}
4326
4327merge:
4328	delta_truesize = skb->truesize;
4329	if (offset > headlen) {
4330		unsigned int eat = offset - headlen;
4331
4332		skb_frag_off_add(&skbinfo->frags[0], eat);
4333		skb_frag_size_sub(&skbinfo->frags[0], eat);
4334		skb->data_len -= eat;
4335		skb->len -= eat;
4336		offset = headlen;
4337	}
4338
4339	__skb_pull(skb, offset);
4340
4341	if (NAPI_GRO_CB(p)->last == p)
4342		skb_shinfo(p)->frag_list = skb;
4343	else
4344		NAPI_GRO_CB(p)->last->next = skb;
4345	NAPI_GRO_CB(p)->last = skb;
4346	__skb_header_release(skb);
4347	lp = p;
4348
4349done:
4350	NAPI_GRO_CB(p)->count++;
4351	p->data_len += len;
4352	p->truesize += delta_truesize;
4353	p->len += len;
4354	if (lp != p) {
4355		lp->data_len += len;
4356		lp->truesize += delta_truesize;
4357		lp->len += len;
4358	}
4359	NAPI_GRO_CB(skb)->same_flow = 1;
4360	return 0;
4361}
4362
4363#ifdef CONFIG_SKB_EXTENSIONS
4364#define SKB_EXT_ALIGN_VALUE	8
4365#define SKB_EXT_CHUNKSIZEOF(x)	(ALIGN((sizeof(x)), SKB_EXT_ALIGN_VALUE) / SKB_EXT_ALIGN_VALUE)
4366
4367static const u8 skb_ext_type_len[] = {
4368#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
4369	[SKB_EXT_BRIDGE_NF] = SKB_EXT_CHUNKSIZEOF(struct nf_bridge_info),
4370#endif
4371#ifdef CONFIG_XFRM
4372	[SKB_EXT_SEC_PATH] = SKB_EXT_CHUNKSIZEOF(struct sec_path),
4373#endif
4374#if IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
4375	[TC_SKB_EXT] = SKB_EXT_CHUNKSIZEOF(struct tc_skb_ext),
4376#endif
4377#if IS_ENABLED(CONFIG_MPTCP)
4378	[SKB_EXT_MPTCP] = SKB_EXT_CHUNKSIZEOF(struct mptcp_ext),
4379#endif
4380};
4381
4382static __always_inline unsigned int skb_ext_total_length(void)
4383{
4384	return SKB_EXT_CHUNKSIZEOF(struct skb_ext) +
4385#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
4386		skb_ext_type_len[SKB_EXT_BRIDGE_NF] +
4387#endif
4388#ifdef CONFIG_XFRM
4389		skb_ext_type_len[SKB_EXT_SEC_PATH] +
4390#endif
4391#if IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
4392		skb_ext_type_len[TC_SKB_EXT] +
4393#endif
4394#if IS_ENABLED(CONFIG_MPTCP)
4395		skb_ext_type_len[SKB_EXT_MPTCP] +
4396#endif
4397		0;
4398}
4399
4400static void skb_extensions_init(void)
4401{
4402	BUILD_BUG_ON(SKB_EXT_NUM >= 8);
4403	BUILD_BUG_ON(skb_ext_total_length() > 255);
4404
4405	skbuff_ext_cache = kmem_cache_create("skbuff_ext_cache",
4406					     SKB_EXT_ALIGN_VALUE * skb_ext_total_length(),
4407					     0,
4408					     SLAB_HWCACHE_ALIGN|SLAB_PANIC,
4409					     NULL);
4410}
4411#else
4412static void skb_extensions_init(void) {}
4413#endif
4414
4415void __init skb_init(void)
4416{
4417	skbuff_head_cache = kmem_cache_create_usercopy("skbuff_head_cache",
4418					      sizeof(struct sk_buff),
4419					      0,
4420					      SLAB_HWCACHE_ALIGN|SLAB_PANIC,
4421					      offsetof(struct sk_buff, cb),
4422					      sizeof_field(struct sk_buff, cb),
4423					      NULL);
4424	skbuff_fclone_cache = kmem_cache_create("skbuff_fclone_cache",
4425						sizeof(struct sk_buff_fclones),
4426						0,
4427						SLAB_HWCACHE_ALIGN|SLAB_PANIC,
4428						NULL);
4429	skb_extensions_init();
4430}
4431
4432static int
4433__skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len,
4434	       unsigned int recursion_level)
4435{
4436	int start = skb_headlen(skb);
4437	int i, copy = start - offset;
4438	struct sk_buff *frag_iter;
4439	int elt = 0;
4440
4441	if (unlikely(recursion_level >= 24))
4442		return -EMSGSIZE;
4443
4444	if (copy > 0) {
4445		if (copy > len)
4446			copy = len;
4447		sg_set_buf(sg, skb->data + offset, copy);
4448		elt++;
4449		if ((len -= copy) == 0)
4450			return elt;
4451		offset += copy;
4452	}
4453
4454	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
4455		int end;
4456
4457		WARN_ON(start > offset + len);
4458
4459		end = start + skb_frag_size(&skb_shinfo(skb)->frags[i]);
4460		if ((copy = end - offset) > 0) {
4461			skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
4462			if (unlikely(elt && sg_is_last(&sg[elt - 1])))
4463				return -EMSGSIZE;
4464
4465			if (copy > len)
4466				copy = len;
4467			sg_set_page(&sg[elt], skb_frag_page(frag), copy,
4468				    skb_frag_off(frag) + offset - start);
4469			elt++;
4470			if (!(len -= copy))
4471				return elt;
4472			offset += copy;
4473		}
4474		start = end;
4475	}
4476
4477	skb_walk_frags(skb, frag_iter) {
4478		int end, ret;
4479
4480		WARN_ON(start > offset + len);
4481
4482		end = start + frag_iter->len;
4483		if ((copy = end - offset) > 0) {
4484			if (unlikely(elt && sg_is_last(&sg[elt - 1])))
4485				return -EMSGSIZE;
4486
4487			if (copy > len)
4488				copy = len;
4489			ret = __skb_to_sgvec(frag_iter, sg+elt, offset - start,
4490					      copy, recursion_level + 1);
4491			if (unlikely(ret < 0))
4492				return ret;
4493			elt += ret;
4494			if ((len -= copy) == 0)
4495				return elt;
4496			offset += copy;
4497		}
4498		start = end;
4499	}
4500	BUG_ON(len);
4501	return elt;
4502}
4503
4504/**
4505 *	skb_to_sgvec - Fill a scatter-gather list from a socket buffer
4506 *	@skb: Socket buffer containing the buffers to be mapped
4507 *	@sg: The scatter-gather list to map into
4508 *	@offset: The offset into the buffer's contents to start mapping
4509 *	@len: Length of buffer space to be mapped
4510 *
4511 *	Fill the specified scatter-gather list with mappings/pointers into a
4512 *	region of the buffer space attached to a socket buffer. Returns either
4513 *	the number of scatterlist items used, or -EMSGSIZE if the contents
4514 *	could not fit.
4515 */
4516int skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
4517{
4518	int nsg = __skb_to_sgvec(skb, sg, offset, len, 0);
4519
4520	if (nsg <= 0)
4521		return nsg;
4522
4523	sg_mark_end(&sg[nsg - 1]);
4524
4525	return nsg;
4526}
4527EXPORT_SYMBOL_GPL(skb_to_sgvec);
4528
4529/* As compared with skb_to_sgvec, skb_to_sgvec_nomark only map skb to given
4530 * sglist without mark the sg which contain last skb data as the end.
4531 * So the caller can mannipulate sg list as will when padding new data after
4532 * the first call without calling sg_unmark_end to expend sg list.
4533 *
4534 * Scenario to use skb_to_sgvec_nomark:
4535 * 1. sg_init_table
4536 * 2. skb_to_sgvec_nomark(payload1)
4537 * 3. skb_to_sgvec_nomark(payload2)
4538 *
4539 * This is equivalent to:
4540 * 1. sg_init_table
4541 * 2. skb_to_sgvec(payload1)
4542 * 3. sg_unmark_end
4543 * 4. skb_to_sgvec(payload2)
4544 *
4545 * When mapping mutilple payload conditionally, skb_to_sgvec_nomark
4546 * is more preferable.
4547 */
4548int skb_to_sgvec_nomark(struct sk_buff *skb, struct scatterlist *sg,
4549			int offset, int len)
4550{
4551	return __skb_to_sgvec(skb, sg, offset, len, 0);
4552}
4553EXPORT_SYMBOL_GPL(skb_to_sgvec_nomark);
4554
4555
4556
4557/**
4558 *	skb_cow_data - Check that a socket buffer's data buffers are writable
4559 *	@skb: The socket buffer to check.
4560 *	@tailbits: Amount of trailing space to be added
4561 *	@trailer: Returned pointer to the skb where the @tailbits space begins
4562 *
4563 *	Make sure that the data buffers attached to a socket buffer are
4564 *	writable. If they are not, private copies are made of the data buffers
4565 *	and the socket buffer is set to use these instead.
4566 *
4567 *	If @tailbits is given, make sure that there is space to write @tailbits
4568 *	bytes of data beyond current end of socket buffer.  @trailer will be
4569 *	set to point to the skb in which this space begins.
4570 *
4571 *	The number of scatterlist elements required to completely map the
4572 *	COW'd and extended socket buffer will be returned.
4573 */
4574int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer)
4575{
4576	int copyflag;
4577	int elt;
4578	struct sk_buff *skb1, **skb_p;
4579
4580	/* If skb is cloned or its head is paged, reallocate
4581	 * head pulling out all the pages (pages are considered not writable
4582	 * at the moment even if they are anonymous).
4583	 */
4584	if ((skb_cloned(skb) || skb_shinfo(skb)->nr_frags) &&
4585	    !__pskb_pull_tail(skb, __skb_pagelen(skb)))
4586		return -ENOMEM;
4587
4588	/* Easy case. Most of packets will go this way. */
4589	if (!skb_has_frag_list(skb)) {
4590		/* A little of trouble, not enough of space for trailer.
4591		 * This should not happen, when stack is tuned to generate
4592		 * good frames. OK, on miss we reallocate and reserve even more
4593		 * space, 128 bytes is fair. */
4594
4595		if (skb_tailroom(skb) < tailbits &&
4596		    pskb_expand_head(skb, 0, tailbits-skb_tailroom(skb)+128, GFP_ATOMIC))
4597			return -ENOMEM;
4598
4599		/* Voila! */
4600		*trailer = skb;
4601		return 1;
4602	}
4603
4604	/* Misery. We are in troubles, going to mincer fragments... */
4605
4606	elt = 1;
4607	skb_p = &skb_shinfo(skb)->frag_list;
4608	copyflag = 0;
4609
4610	while ((skb1 = *skb_p) != NULL) {
4611		int ntail = 0;
4612
4613		/* The fragment is partially pulled by someone,
4614		 * this can happen on input. Copy it and everything
4615		 * after it. */
4616
4617		if (skb_shared(skb1))
4618			copyflag = 1;
4619
4620		/* If the skb is the last, worry about trailer. */
4621
4622		if (skb1->next == NULL && tailbits) {
4623			if (skb_shinfo(skb1)->nr_frags ||
4624			    skb_has_frag_list(skb1) ||
4625			    skb_tailroom(skb1) < tailbits)
4626				ntail = tailbits + 128;
4627		}
4628
4629		if (copyflag ||
4630		    skb_cloned(skb1) ||
4631		    ntail ||
4632		    skb_shinfo(skb1)->nr_frags ||
4633		    skb_has_frag_list(skb1)) {
4634			struct sk_buff *skb2;
4635
4636			/* Fuck, we are miserable poor guys... */
4637			if (ntail == 0)
4638				skb2 = skb_copy(skb1, GFP_ATOMIC);
4639			else
4640				skb2 = skb_copy_expand(skb1,
4641						       skb_headroom(skb1),
4642						       ntail,
4643						       GFP_ATOMIC);
4644			if (unlikely(skb2 == NULL))
4645				return -ENOMEM;
4646
4647			if (skb1->sk)
4648				skb_set_owner_w(skb2, skb1->sk);
4649
4650			/* Looking around. Are we still alive?
4651			 * OK, link new skb, drop old one */
4652
4653			skb2->next = skb1->next;
4654			*skb_p = skb2;
4655			kfree_skb(skb1);
4656			skb1 = skb2;
4657		}
4658		elt++;
4659		*trailer = skb1;
4660		skb_p = &skb1->next;
4661	}
4662
4663	return elt;
4664}
4665EXPORT_SYMBOL_GPL(skb_cow_data);
4666
4667static void sock_rmem_free(struct sk_buff *skb)
4668{
4669	struct sock *sk = skb->sk;
4670
4671	atomic_sub(skb->truesize, &sk->sk_rmem_alloc);
4672}
4673
4674static void skb_set_err_queue(struct sk_buff *skb)
4675{
4676	/* pkt_type of skbs received on local sockets is never PACKET_OUTGOING.
4677	 * So, it is safe to (mis)use it to mark skbs on the error queue.
4678	 */
4679	skb->pkt_type = PACKET_OUTGOING;
4680	BUILD_BUG_ON(PACKET_OUTGOING == 0);
4681}
4682
4683/*
4684 * Note: We dont mem charge error packets (no sk_forward_alloc changes)
4685 */
4686int sock_queue_err_skb(struct sock *sk, struct sk_buff *skb)
4687{
4688	if (atomic_read(&sk->sk_rmem_alloc) + skb->truesize >=
4689	    (unsigned int)READ_ONCE(sk->sk_rcvbuf))
4690		return -ENOMEM;
4691
4692	skb_orphan(skb);
4693	skb->sk = sk;
4694	skb->destructor = sock_rmem_free;
4695	atomic_add(skb->truesize, &sk->sk_rmem_alloc);
4696	skb_set_err_queue(skb);
4697
4698	/* before exiting rcu section, make sure dst is refcounted */
4699	skb_dst_force(skb);
4700
4701	skb_queue_tail(&sk->sk_error_queue, skb);
4702	if (!sock_flag(sk, SOCK_DEAD))
4703		sk_error_report(sk);
4704	return 0;
4705}
4706EXPORT_SYMBOL(sock_queue_err_skb);
4707
4708static bool is_icmp_err_skb(const struct sk_buff *skb)
4709{
4710	return skb && (SKB_EXT_ERR(skb)->ee.ee_origin == SO_EE_ORIGIN_ICMP ||
4711		       SKB_EXT_ERR(skb)->ee.ee_origin == SO_EE_ORIGIN_ICMP6);
4712}
4713
4714struct sk_buff *sock_dequeue_err_skb(struct sock *sk)
4715{
4716	struct sk_buff_head *q = &sk->sk_error_queue;
4717	struct sk_buff *skb, *skb_next = NULL;
4718	bool icmp_next = false;
4719	unsigned long flags;
4720
4721	spin_lock_irqsave(&q->lock, flags);
4722	skb = __skb_dequeue(q);
4723	if (skb && (skb_next = skb_peek(q))) {
4724		icmp_next = is_icmp_err_skb(skb_next);
4725		if (icmp_next)
4726			sk->sk_err = SKB_EXT_ERR(skb_next)->ee.ee_errno;
4727	}
4728	spin_unlock_irqrestore(&q->lock, flags);
4729
4730	if (is_icmp_err_skb(skb) && !icmp_next)
4731		sk->sk_err = 0;
4732
4733	if (skb_next)
4734		sk_error_report(sk);
4735
4736	return skb;
4737}
4738EXPORT_SYMBOL(sock_dequeue_err_skb);
4739
4740/**
4741 * skb_clone_sk - create clone of skb, and take reference to socket
4742 * @skb: the skb to clone
4743 *
4744 * This function creates a clone of a buffer that holds a reference on
4745 * sk_refcnt.  Buffers created via this function are meant to be
4746 * returned using sock_queue_err_skb, or free via kfree_skb.
4747 *
4748 * When passing buffers allocated with this function to sock_queue_err_skb
4749 * it is necessary to wrap the call with sock_hold/sock_put in order to
4750 * prevent the socket from being released prior to being enqueued on
4751 * the sk_error_queue.
4752 */
4753struct sk_buff *skb_clone_sk(struct sk_buff *skb)
4754{
4755	struct sock *sk = skb->sk;
4756	struct sk_buff *clone;
4757
4758	if (!sk || !refcount_inc_not_zero(&sk->sk_refcnt))
4759		return NULL;
4760
4761	clone = skb_clone(skb, GFP_ATOMIC);
4762	if (!clone) {
4763		sock_put(sk);
4764		return NULL;
4765	}
4766
4767	clone->sk = sk;
4768	clone->destructor = sock_efree;
4769
4770	return clone;
4771}
4772EXPORT_SYMBOL(skb_clone_sk);
4773
4774static void __skb_complete_tx_timestamp(struct sk_buff *skb,
4775					struct sock *sk,
4776					int tstype,
4777					bool opt_stats)
4778{
4779	struct sock_exterr_skb *serr;
4780	int err;
4781
4782	BUILD_BUG_ON(sizeof(struct sock_exterr_skb) > sizeof(skb->cb));
4783
4784	serr = SKB_EXT_ERR(skb);
4785	memset(serr, 0, sizeof(*serr));
4786	serr->ee.ee_errno = ENOMSG;
4787	serr->ee.ee_origin = SO_EE_ORIGIN_TIMESTAMPING;
4788	serr->ee.ee_info = tstype;
4789	serr->opt_stats = opt_stats;
4790	serr->header.h4.iif = skb->dev ? skb->dev->ifindex : 0;
4791	if (sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID) {
4792		serr->ee.ee_data = skb_shinfo(skb)->tskey;
4793		if (sk->sk_protocol == IPPROTO_TCP &&
4794		    sk->sk_type == SOCK_STREAM)
4795			serr->ee.ee_data -= sk->sk_tskey;
4796	}
4797
4798	err = sock_queue_err_skb(sk, skb);
4799
4800	if (err)
4801		kfree_skb(skb);
4802}
4803
4804static bool skb_may_tx_timestamp(struct sock *sk, bool tsonly)
4805{
4806	bool ret;
4807
4808	if (likely(sysctl_tstamp_allow_data || tsonly))
4809		return true;
4810
4811	read_lock_bh(&sk->sk_callback_lock);
4812	ret = sk->sk_socket && sk->sk_socket->file &&
4813	      file_ns_capable(sk->sk_socket->file, &init_user_ns, CAP_NET_RAW);
4814	read_unlock_bh(&sk->sk_callback_lock);
4815	return ret;
4816}
4817
4818void skb_complete_tx_timestamp(struct sk_buff *skb,
4819			       struct skb_shared_hwtstamps *hwtstamps)
4820{
4821	struct sock *sk = skb->sk;
4822
4823	if (!skb_may_tx_timestamp(sk, false))
4824		goto err;
4825
4826	/* Take a reference to prevent skb_orphan() from freeing the socket,
4827	 * but only if the socket refcount is not zero.
4828	 */
4829	if (likely(refcount_inc_not_zero(&sk->sk_refcnt))) {
4830		*skb_hwtstamps(skb) = *hwtstamps;
4831		__skb_complete_tx_timestamp(skb, sk, SCM_TSTAMP_SND, false);
4832		sock_put(sk);
4833		return;
4834	}
4835
4836err:
4837	kfree_skb(skb);
4838}
4839EXPORT_SYMBOL_GPL(skb_complete_tx_timestamp);
4840
4841void __skb_tstamp_tx(struct sk_buff *orig_skb,
4842		     const struct sk_buff *ack_skb,
4843		     struct skb_shared_hwtstamps *hwtstamps,
4844		     struct sock *sk, int tstype)
4845{
4846	struct sk_buff *skb;
4847	bool tsonly, opt_stats = false;
4848
4849	if (!sk)
4850		return;
4851
4852	if (!hwtstamps && !(sk->sk_tsflags & SOF_TIMESTAMPING_OPT_TX_SWHW) &&
4853	    skb_shinfo(orig_skb)->tx_flags & SKBTX_IN_PROGRESS)
4854		return;
4855
4856	tsonly = sk->sk_tsflags & SOF_TIMESTAMPING_OPT_TSONLY;
4857	if (!skb_may_tx_timestamp(sk, tsonly))
4858		return;
4859
4860	if (tsonly) {
4861#ifdef CONFIG_INET
4862		if ((sk->sk_tsflags & SOF_TIMESTAMPING_OPT_STATS) &&
4863		    sk->sk_protocol == IPPROTO_TCP &&
4864		    sk->sk_type == SOCK_STREAM) {
4865			skb = tcp_get_timestamping_opt_stats(sk, orig_skb,
4866							     ack_skb);
4867			opt_stats = true;
4868		} else
4869#endif
4870			skb = alloc_skb(0, GFP_ATOMIC);
4871	} else {
4872		skb = skb_clone(orig_skb, GFP_ATOMIC);
4873	}
4874	if (!skb)
4875		return;
4876
4877	if (tsonly) {
4878		skb_shinfo(skb)->tx_flags |= skb_shinfo(orig_skb)->tx_flags &
4879					     SKBTX_ANY_TSTAMP;
4880		skb_shinfo(skb)->tskey = skb_shinfo(orig_skb)->tskey;
4881	}
4882
4883	if (hwtstamps)
4884		*skb_hwtstamps(skb) = *hwtstamps;
4885	else
4886		skb->tstamp = ktime_get_real();
4887
4888	__skb_complete_tx_timestamp(skb, sk, tstype, opt_stats);
4889}
4890EXPORT_SYMBOL_GPL(__skb_tstamp_tx);
4891
4892void skb_tstamp_tx(struct sk_buff *orig_skb,
4893		   struct skb_shared_hwtstamps *hwtstamps)
4894{
4895	return __skb_tstamp_tx(orig_skb, NULL, hwtstamps, orig_skb->sk,
4896			       SCM_TSTAMP_SND);
4897}
4898EXPORT_SYMBOL_GPL(skb_tstamp_tx);
4899
4900void skb_complete_wifi_ack(struct sk_buff *skb, bool acked)
4901{
4902	struct sock *sk = skb->sk;
4903	struct sock_exterr_skb *serr;
4904	int err = 1;
4905
4906	skb->wifi_acked_valid = 1;
4907	skb->wifi_acked = acked;
4908
4909	serr = SKB_EXT_ERR(skb);
4910	memset(serr, 0, sizeof(*serr));
4911	serr->ee.ee_errno = ENOMSG;
4912	serr->ee.ee_origin = SO_EE_ORIGIN_TXSTATUS;
4913
4914	/* Take a reference to prevent skb_orphan() from freeing the socket,
4915	 * but only if the socket refcount is not zero.
4916	 */
4917	if (likely(refcount_inc_not_zero(&sk->sk_refcnt))) {
4918		err = sock_queue_err_skb(sk, skb);
4919		sock_put(sk);
4920	}
4921	if (err)
4922		kfree_skb(skb);
4923}
4924EXPORT_SYMBOL_GPL(skb_complete_wifi_ack);
4925
4926/**
4927 * skb_partial_csum_set - set up and verify partial csum values for packet
4928 * @skb: the skb to set
4929 * @start: the number of bytes after skb->data to start checksumming.
4930 * @off: the offset from start to place the checksum.
4931 *
4932 * For untrusted partially-checksummed packets, we need to make sure the values
4933 * for skb->csum_start and skb->csum_offset are valid so we don't oops.
4934 *
4935 * This function checks and sets those values and skb->ip_summed: if this
4936 * returns false you should drop the packet.
4937 */
4938bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off)
4939{
4940	u32 csum_end = (u32)start + (u32)off + sizeof(__sum16);
4941	u32 csum_start = skb_headroom(skb) + (u32)start;
4942
4943	if (unlikely(csum_start > U16_MAX || csum_end > skb_headlen(skb))) {
4944		net_warn_ratelimited("bad partial csum: csum=%u/%u headroom=%u headlen=%u\n",
4945				     start, off, skb_headroom(skb), skb_headlen(skb));
4946		return false;
4947	}
4948	skb->ip_summed = CHECKSUM_PARTIAL;
4949	skb->csum_start = csum_start;
4950	skb->csum_offset = off;
4951	skb_set_transport_header(skb, start);
4952	return true;
4953}
4954EXPORT_SYMBOL_GPL(skb_partial_csum_set);
4955
4956static int skb_maybe_pull_tail(struct sk_buff *skb, unsigned int len,
4957			       unsigned int max)
4958{
4959	if (skb_headlen(skb) >= len)
4960		return 0;
4961
4962	/* If we need to pullup then pullup to the max, so we
4963	 * won't need to do it again.
4964	 */
4965	if (max > skb->len)
4966		max = skb->len;
4967
4968	if (__pskb_pull_tail(skb, max - skb_headlen(skb)) == NULL)
4969		return -ENOMEM;
4970
4971	if (skb_headlen(skb) < len)
4972		return -EPROTO;
4973
4974	return 0;
4975}
4976
4977#define MAX_TCP_HDR_LEN (15 * 4)
4978
4979static __sum16 *skb_checksum_setup_ip(struct sk_buff *skb,
4980				      typeof(IPPROTO_IP) proto,
4981				      unsigned int off)
4982{
4983	int err;
4984
4985	switch (proto) {
4986	case IPPROTO_TCP:
4987		err = skb_maybe_pull_tail(skb, off + sizeof(struct tcphdr),
4988					  off + MAX_TCP_HDR_LEN);
4989		if (!err && !skb_partial_csum_set(skb, off,
4990						  offsetof(struct tcphdr,
4991							   check)))
4992			err = -EPROTO;
4993		return err ? ERR_PTR(err) : &tcp_hdr(skb)->check;
4994
4995	case IPPROTO_UDP:
4996		err = skb_maybe_pull_tail(skb, off + sizeof(struct udphdr),
4997					  off + sizeof(struct udphdr));
4998		if (!err && !skb_partial_csum_set(skb, off,
4999						  offsetof(struct udphdr,
5000							   check)))
5001			err = -EPROTO;
5002		return err ? ERR_PTR(err) : &udp_hdr(skb)->check;
5003	}
5004
5005	return ERR_PTR(-EPROTO);
5006}
5007
5008/* This value should be large enough to cover a tagged ethernet header plus
5009 * maximally sized IP and TCP or UDP headers.
5010 */
5011#define MAX_IP_HDR_LEN 128
5012
5013static int skb_checksum_setup_ipv4(struct sk_buff *skb, bool recalculate)
5014{
5015	unsigned int off;
5016	bool fragment;
5017	__sum16 *csum;
5018	int err;
5019
5020	fragment = false;
5021
5022	err = skb_maybe_pull_tail(skb,
5023				  sizeof(struct iphdr),
5024				  MAX_IP_HDR_LEN);
5025	if (err < 0)
5026		goto out;
5027
5028	if (ip_is_fragment(ip_hdr(skb)))
5029		fragment = true;
5030
5031	off = ip_hdrlen(skb);
5032
5033	err = -EPROTO;
5034
5035	if (fragment)
5036		goto out;
5037
5038	csum = skb_checksum_setup_ip(skb, ip_hdr(skb)->protocol, off);
5039	if (IS_ERR(csum))
5040		return PTR_ERR(csum);
5041
5042	if (recalculate)
5043		*csum = ~csum_tcpudp_magic(ip_hdr(skb)->saddr,
5044					   ip_hdr(skb)->daddr,
5045					   skb->len - off,
5046					   ip_hdr(skb)->protocol, 0);
5047	err = 0;
5048
5049out:
5050	return err;
5051}
5052
5053/* This value should be large enough to cover a tagged ethernet header plus
5054 * an IPv6 header, all options, and a maximal TCP or UDP header.
5055 */
5056#define MAX_IPV6_HDR_LEN 256
5057
5058#define OPT_HDR(type, skb, off) \
5059	(type *)(skb_network_header(skb) + (off))
5060
5061static int skb_checksum_setup_ipv6(struct sk_buff *skb, bool recalculate)
5062{
5063	int err;
5064	u8 nexthdr;
5065	unsigned int off;
5066	unsigned int len;
5067	bool fragment;
5068	bool done;
5069	__sum16 *csum;
5070
5071	fragment = false;
5072	done = false;
5073
5074	off = sizeof(struct ipv6hdr);
5075
5076	err = skb_maybe_pull_tail(skb, off, MAX_IPV6_HDR_LEN);
5077	if (err < 0)
5078		goto out;
5079
5080	nexthdr = ipv6_hdr(skb)->nexthdr;
5081
5082	len = sizeof(struct ipv6hdr) + ntohs(ipv6_hdr(skb)->payload_len);
5083	while (off <= len && !done) {
5084		switch (nexthdr) {
5085		case IPPROTO_DSTOPTS:
5086		case IPPROTO_HOPOPTS:
5087		case IPPROTO_ROUTING: {
5088			struct ipv6_opt_hdr *hp;
5089
5090			err = skb_maybe_pull_tail(skb,
5091						  off +
5092						  sizeof(struct ipv6_opt_hdr),
5093						  MAX_IPV6_HDR_LEN);
5094			if (err < 0)
5095				goto out;
5096
5097			hp = OPT_HDR(struct ipv6_opt_hdr, skb, off);
5098			nexthdr = hp->nexthdr;
5099			off += ipv6_optlen(hp);
5100			break;
5101		}
5102		case IPPROTO_AH: {
5103			struct ip_auth_hdr *hp;
5104
5105			err = skb_maybe_pull_tail(skb,
5106						  off +
5107						  sizeof(struct ip_auth_hdr),
5108						  MAX_IPV6_HDR_LEN);
5109			if (err < 0)
5110				goto out;
5111
5112			hp = OPT_HDR(struct ip_auth_hdr, skb, off);
5113			nexthdr = hp->nexthdr;
5114			off += ipv6_authlen(hp);
5115			break;
5116		}
5117		case IPPROTO_FRAGMENT: {
5118			struct frag_hdr *hp;
5119
5120			err = skb_maybe_pull_tail(skb,
5121						  off +
5122						  sizeof(struct frag_hdr),
5123						  MAX_IPV6_HDR_LEN);
5124			if (err < 0)
5125				goto out;
5126
5127			hp = OPT_HDR(struct frag_hdr, skb, off);
5128
5129			if (hp->frag_off & htons(IP6_OFFSET | IP6_MF))
5130				fragment = true;
5131
5132			nexthdr = hp->nexthdr;
5133			off += sizeof(struct frag_hdr);
5134			break;
5135		}
5136		default:
5137			done = true;
5138			break;
5139		}
5140	}
5141
5142	err = -EPROTO;
5143
5144	if (!done || fragment)
5145		goto out;
5146
5147	csum = skb_checksum_setup_ip(skb, nexthdr, off);
5148	if (IS_ERR(csum))
5149		return PTR_ERR(csum);
5150
5151	if (recalculate)
5152		*csum = ~csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
5153					 &ipv6_hdr(skb)->daddr,
5154					 skb->len - off, nexthdr, 0);
5155	err = 0;
5156
5157out:
5158	return err;
5159}
5160
5161/**
5162 * skb_checksum_setup - set up partial checksum offset
5163 * @skb: the skb to set up
5164 * @recalculate: if true the pseudo-header checksum will be recalculated
5165 */
5166int skb_checksum_setup(struct sk_buff *skb, bool recalculate)
5167{
5168	int err;
5169
5170	switch (skb->protocol) {
5171	case htons(ETH_P_IP):
5172		err = skb_checksum_setup_ipv4(skb, recalculate);
5173		break;
5174
5175	case htons(ETH_P_IPV6):
5176		err = skb_checksum_setup_ipv6(skb, recalculate);
5177		break;
5178
5179	default:
5180		err = -EPROTO;
5181		break;
5182	}
5183
5184	return err;
5185}
5186EXPORT_SYMBOL(skb_checksum_setup);
5187
5188/**
5189 * skb_checksum_maybe_trim - maybe trims the given skb
5190 * @skb: the skb to check
5191 * @transport_len: the data length beyond the network header
5192 *
5193 * Checks whether the given skb has data beyond the given transport length.
5194 * If so, returns a cloned skb trimmed to this transport length.
5195 * Otherwise returns the provided skb. Returns NULL in error cases
5196 * (e.g. transport_len exceeds skb length or out-of-memory).
5197 *
5198 * Caller needs to set the skb transport header and free any returned skb if it
5199 * differs from the provided skb.
5200 */
5201static struct sk_buff *skb_checksum_maybe_trim(struct sk_buff *skb,
5202					       unsigned int transport_len)
5203{
5204	struct sk_buff *skb_chk;
5205	unsigned int len = skb_transport_offset(skb) + transport_len;
5206	int ret;
5207
5208	if (skb->len < len)
5209		return NULL;
5210	else if (skb->len == len)
5211		return skb;
5212
5213	skb_chk = skb_clone(skb, GFP_ATOMIC);
5214	if (!skb_chk)
5215		return NULL;
5216
5217	ret = pskb_trim_rcsum(skb_chk, len);
5218	if (ret) {
5219		kfree_skb(skb_chk);
5220		return NULL;
5221	}
5222
5223	return skb_chk;
5224}
5225
5226/**
5227 * skb_checksum_trimmed - validate checksum of an skb
5228 * @skb: the skb to check
5229 * @transport_len: the data length beyond the network header
5230 * @skb_chkf: checksum function to use
5231 *
5232 * Applies the given checksum function skb_chkf to the provided skb.
5233 * Returns a checked and maybe trimmed skb. Returns NULL on error.
5234 *
5235 * If the skb has data beyond the given transport length, then a
5236 * trimmed & cloned skb is checked and returned.
5237 *
5238 * Caller needs to set the skb transport header and free any returned skb if it
5239 * differs from the provided skb.
5240 */
5241struct sk_buff *skb_checksum_trimmed(struct sk_buff *skb,
5242				     unsigned int transport_len,
5243				     __sum16(*skb_chkf)(struct sk_buff *skb))
5244{
5245	struct sk_buff *skb_chk;
5246	unsigned int offset = skb_transport_offset(skb);
5247	__sum16 ret;
5248
5249	skb_chk = skb_checksum_maybe_trim(skb, transport_len);
5250	if (!skb_chk)
5251		goto err;
5252
5253	if (!pskb_may_pull(skb_chk, offset))
5254		goto err;
5255
5256	skb_pull_rcsum(skb_chk, offset);
5257	ret = skb_chkf(skb_chk);
5258	skb_push_rcsum(skb_chk, offset);
5259
5260	if (ret)
5261		goto err;
5262
5263	return skb_chk;
5264
5265err:
5266	if (skb_chk && skb_chk != skb)
5267		kfree_skb(skb_chk);
5268
5269	return NULL;
5270
5271}
5272EXPORT_SYMBOL(skb_checksum_trimmed);
5273
5274void __skb_warn_lro_forwarding(const struct sk_buff *skb)
5275{
5276	net_warn_ratelimited("%s: received packets cannot be forwarded while LRO is enabled\n",
5277			     skb->dev->name);
5278}
5279EXPORT_SYMBOL(__skb_warn_lro_forwarding);
5280
5281void kfree_skb_partial(struct sk_buff *skb, bool head_stolen)
5282{
5283	if (head_stolen) {
5284		skb_release_head_state(skb);
5285		kmem_cache_free(skbuff_head_cache, skb);
5286	} else {
5287		__kfree_skb(skb);
5288	}
5289}
5290EXPORT_SYMBOL(kfree_skb_partial);
5291
5292/**
5293 * skb_try_coalesce - try to merge skb to prior one
5294 * @to: prior buffer
5295 * @from: buffer to add
5296 * @fragstolen: pointer to boolean
5297 * @delta_truesize: how much more was allocated than was requested
5298 */
5299bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from,
5300		      bool *fragstolen, int *delta_truesize)
5301{
5302	struct skb_shared_info *to_shinfo, *from_shinfo;
5303	int i, delta, len = from->len;
5304
5305	*fragstolen = false;
5306
5307	if (skb_cloned(to))
5308		return false;
5309
5310	/* The page pool signature of struct page will eventually figure out
5311	 * which pages can be recycled or not but for now let's prohibit slab
5312	 * allocated and page_pool allocated SKBs from being coalesced.
5313	 */
5314	if (to->pp_recycle != from->pp_recycle)
5315		return false;
5316
5317	if (len <= skb_tailroom(to)) {
5318		if (len)
5319			BUG_ON(skb_copy_bits(from, 0, skb_put(to, len), len));
5320		*delta_truesize = 0;
5321		return true;
5322	}
5323
5324	to_shinfo = skb_shinfo(to);
5325	from_shinfo = skb_shinfo(from);
5326	if (to_shinfo->frag_list || from_shinfo->frag_list)
5327		return false;
5328	if (skb_zcopy(to) || skb_zcopy(from))
5329		return false;
5330
5331	if (skb_headlen(from) != 0) {
5332		struct page *page;
5333		unsigned int offset;
5334
5335		if (to_shinfo->nr_frags +
5336		    from_shinfo->nr_frags >= MAX_SKB_FRAGS)
5337			return false;
5338
5339		if (skb_head_is_locked(from))
5340			return false;
5341
5342		delta = from->truesize - SKB_DATA_ALIGN(sizeof(struct sk_buff));
5343
5344		page = virt_to_head_page(from->head);
5345		offset = from->data - (unsigned char *)page_address(page);
5346
5347		skb_fill_page_desc(to, to_shinfo->nr_frags,
5348				   page, offset, skb_headlen(from));
5349		*fragstolen = true;
5350	} else {
5351		if (to_shinfo->nr_frags +
5352		    from_shinfo->nr_frags > MAX_SKB_FRAGS)
5353			return false;
5354
5355		delta = from->truesize - SKB_TRUESIZE(skb_end_offset(from));
5356	}
5357
5358	WARN_ON_ONCE(delta < len);
5359
5360	memcpy(to_shinfo->frags + to_shinfo->nr_frags,
5361	       from_shinfo->frags,
5362	       from_shinfo->nr_frags * sizeof(skb_frag_t));
5363	to_shinfo->nr_frags += from_shinfo->nr_frags;
5364
5365	if (!skb_cloned(from))
5366		from_shinfo->nr_frags = 0;
5367
5368	/* if the skb is not cloned this does nothing
5369	 * since we set nr_frags to 0.
5370	 */
5371	for (i = 0; i < from_shinfo->nr_frags; i++)
5372		__skb_frag_ref(&from_shinfo->frags[i]);
5373
5374	to->truesize += delta;
5375	to->len += len;
5376	to->data_len += len;
5377
5378	*delta_truesize = delta;
5379	return true;
5380}
5381EXPORT_SYMBOL(skb_try_coalesce);
5382
5383/**
5384 * skb_scrub_packet - scrub an skb
5385 *
5386 * @skb: buffer to clean
5387 * @xnet: packet is crossing netns
5388 *
5389 * skb_scrub_packet can be used after encapsulating or decapsulting a packet
5390 * into/from a tunnel. Some information have to be cleared during these
5391 * operations.
5392 * skb_scrub_packet can also be used to clean a skb before injecting it in
5393 * another namespace (@xnet == true). We have to clear all information in the
5394 * skb that could impact namespace isolation.
5395 */
5396void skb_scrub_packet(struct sk_buff *skb, bool xnet)
5397{
5398	skb->pkt_type = PACKET_HOST;
5399	skb->skb_iif = 0;
5400	skb->ignore_df = 0;
5401	skb_dst_drop(skb);
5402	skb_ext_reset(skb);
5403	nf_reset_ct(skb);
5404	nf_reset_trace(skb);
5405
5406#ifdef CONFIG_NET_SWITCHDEV
5407	skb->offload_fwd_mark = 0;
5408	skb->offload_l3_fwd_mark = 0;
5409#endif
5410
5411	if (!xnet)
5412		return;
5413
5414	ipvs_reset(skb);
5415	skb->mark = 0;
5416	skb->tstamp = 0;
5417}
5418EXPORT_SYMBOL_GPL(skb_scrub_packet);
5419
5420/**
5421 * skb_gso_transport_seglen - Return length of individual segments of a gso packet
5422 *
5423 * @skb: GSO skb
5424 *
5425 * skb_gso_transport_seglen is used to determine the real size of the
5426 * individual segments, including Layer4 headers (TCP/UDP).
5427 *
5428 * The MAC/L2 or network (IP, IPv6) headers are not accounted for.
5429 */
5430static unsigned int skb_gso_transport_seglen(const struct sk_buff *skb)
5431{
5432	const struct skb_shared_info *shinfo = skb_shinfo(skb);
5433	unsigned int thlen = 0;
5434
5435	if (skb->encapsulation) {
5436		thlen = skb_inner_transport_header(skb) -
5437			skb_transport_header(skb);
5438
5439		if (likely(shinfo->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6)))
5440			thlen += inner_tcp_hdrlen(skb);
5441	} else if (likely(shinfo->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6))) {
5442		thlen = tcp_hdrlen(skb);
5443	} else if (unlikely(skb_is_gso_sctp(skb))) {
5444		thlen = sizeof(struct sctphdr);
5445	} else if (shinfo->gso_type & SKB_GSO_UDP_L4) {
5446		thlen = sizeof(struct udphdr);
5447	}
5448	/* UFO sets gso_size to the size of the fragmentation
5449	 * payload, i.e. the size of the L4 (UDP) header is already
5450	 * accounted for.
5451	 */
5452	return thlen + shinfo->gso_size;
5453}
5454
5455/**
5456 * skb_gso_network_seglen - Return length of individual segments of a gso packet
5457 *
5458 * @skb: GSO skb
5459 *
5460 * skb_gso_network_seglen is used to determine the real size of the
5461 * individual segments, including Layer3 (IP, IPv6) and L4 headers (TCP/UDP).
5462 *
5463 * The MAC/L2 header is not accounted for.
5464 */
5465static unsigned int skb_gso_network_seglen(const struct sk_buff *skb)
5466{
5467	unsigned int hdr_len = skb_transport_header(skb) -
5468			       skb_network_header(skb);
5469
5470	return hdr_len + skb_gso_transport_seglen(skb);
5471}
5472
5473/**
5474 * skb_gso_mac_seglen - Return length of individual segments of a gso packet
5475 *
5476 * @skb: GSO skb
5477 *
5478 * skb_gso_mac_seglen is used to determine the real size of the
5479 * individual segments, including MAC/L2, Layer3 (IP, IPv6) and L4
5480 * headers (TCP/UDP).
5481 */
5482static unsigned int skb_gso_mac_seglen(const struct sk_buff *skb)
5483{
5484	unsigned int hdr_len = skb_transport_header(skb) - skb_mac_header(skb);
5485
5486	return hdr_len + skb_gso_transport_seglen(skb);
5487}
5488
5489/**
5490 * skb_gso_size_check - check the skb size, considering GSO_BY_FRAGS
5491 *
5492 * There are a couple of instances where we have a GSO skb, and we
5493 * want to determine what size it would be after it is segmented.
5494 *
5495 * We might want to check:
5496 * -    L3+L4+payload size (e.g. IP forwarding)
5497 * - L2+L3+L4+payload size (e.g. sanity check before passing to driver)
5498 *
5499 * This is a helper to do that correctly considering GSO_BY_FRAGS.
5500 *
5501 * @skb: GSO skb
5502 *
5503 * @seg_len: The segmented length (from skb_gso_*_seglen). In the
5504 *           GSO_BY_FRAGS case this will be [header sizes + GSO_BY_FRAGS].
5505 *
5506 * @max_len: The maximum permissible length.
5507 *
5508 * Returns true if the segmented length <= max length.
5509 */
5510static inline bool skb_gso_size_check(const struct sk_buff *skb,
5511				      unsigned int seg_len,
5512				      unsigned int max_len) {
5513	const struct skb_shared_info *shinfo = skb_shinfo(skb);
5514	const struct sk_buff *iter;
5515
5516	if (shinfo->gso_size != GSO_BY_FRAGS)
5517		return seg_len <= max_len;
5518
5519	/* Undo this so we can re-use header sizes */
5520	seg_len -= GSO_BY_FRAGS;
5521
5522	skb_walk_frags(skb, iter) {
5523		if (seg_len + skb_headlen(iter) > max_len)
5524			return false;
5525	}
5526
5527	return true;
5528}
5529
5530/**
5531 * skb_gso_validate_network_len - Will a split GSO skb fit into a given MTU?
5532 *
5533 * @skb: GSO skb
5534 * @mtu: MTU to validate against
5535 *
5536 * skb_gso_validate_network_len validates if a given skb will fit a
5537 * wanted MTU once split. It considers L3 headers, L4 headers, and the
5538 * payload.
5539 */
5540bool skb_gso_validate_network_len(const struct sk_buff *skb, unsigned int mtu)
5541{
5542	return skb_gso_size_check(skb, skb_gso_network_seglen(skb), mtu);
5543}
5544EXPORT_SYMBOL_GPL(skb_gso_validate_network_len);
5545
5546/**
5547 * skb_gso_validate_mac_len - Will a split GSO skb fit in a given length?
5548 *
5549 * @skb: GSO skb
5550 * @len: length to validate against
5551 *
5552 * skb_gso_validate_mac_len validates if a given skb will fit a wanted
5553 * length once split, including L2, L3 and L4 headers and the payload.
5554 */
5555bool skb_gso_validate_mac_len(const struct sk_buff *skb, unsigned int len)
5556{
5557	return skb_gso_size_check(skb, skb_gso_mac_seglen(skb), len);
5558}
5559EXPORT_SYMBOL_GPL(skb_gso_validate_mac_len);
5560
5561static struct sk_buff *skb_reorder_vlan_header(struct sk_buff *skb)
5562{
5563	int mac_len, meta_len;
5564	void *meta;
5565
5566	if (skb_cow(skb, skb_headroom(skb)) < 0) {
5567		kfree_skb(skb);
5568		return NULL;
5569	}
5570
5571	mac_len = skb->data - skb_mac_header(skb);
5572	if (likely(mac_len > VLAN_HLEN + ETH_TLEN)) {
5573		memmove(skb_mac_header(skb) + VLAN_HLEN, skb_mac_header(skb),
5574			mac_len - VLAN_HLEN - ETH_TLEN);
5575	}
5576
5577	meta_len = skb_metadata_len(skb);
5578	if (meta_len) {
5579		meta = skb_metadata_end(skb) - meta_len;
5580		memmove(meta + VLAN_HLEN, meta, meta_len);
5581	}
5582
5583	skb->mac_header += VLAN_HLEN;
5584	return skb;
5585}
5586
5587struct sk_buff *skb_vlan_untag(struct sk_buff *skb)
5588{
5589	struct vlan_hdr *vhdr;
5590	u16 vlan_tci;
5591
5592	if (unlikely(skb_vlan_tag_present(skb))) {
5593		/* vlan_tci is already set-up so leave this for another time */
5594		return skb;
5595	}
5596
5597	skb = skb_share_check(skb, GFP_ATOMIC);
5598	if (unlikely(!skb))
5599		goto err_free;
5600	/* We may access the two bytes after vlan_hdr in vlan_set_encap_proto(). */
5601	if (unlikely(!pskb_may_pull(skb, VLAN_HLEN + sizeof(unsigned short))))
5602		goto err_free;
5603
5604	vhdr = (struct vlan_hdr *)skb->data;
5605	vlan_tci = ntohs(vhdr->h_vlan_TCI);
5606	__vlan_hwaccel_put_tag(skb, skb->protocol, vlan_tci);
5607
5608	skb_pull_rcsum(skb, VLAN_HLEN);
5609	vlan_set_encap_proto(skb, vhdr);
5610
5611	skb = skb_reorder_vlan_header(skb);
5612	if (unlikely(!skb))
5613		goto err_free;
5614
5615	skb_reset_network_header(skb);
5616	if (!skb_transport_header_was_set(skb))
5617		skb_reset_transport_header(skb);
5618	skb_reset_mac_len(skb);
5619
5620	return skb;
5621
5622err_free:
5623	kfree_skb(skb);
5624	return NULL;
5625}
5626EXPORT_SYMBOL(skb_vlan_untag);
5627
5628int skb_ensure_writable(struct sk_buff *skb, int write_len)
5629{
5630	if (!pskb_may_pull(skb, write_len))
5631		return -ENOMEM;
5632
5633	if (!skb_cloned(skb) || skb_clone_writable(skb, write_len))
5634		return 0;
5635
5636	return pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
5637}
5638EXPORT_SYMBOL(skb_ensure_writable);
5639
5640/* remove VLAN header from packet and update csum accordingly.
5641 * expects a non skb_vlan_tag_present skb with a vlan tag payload
5642 */
5643int __skb_vlan_pop(struct sk_buff *skb, u16 *vlan_tci)
5644{
5645	struct vlan_hdr *vhdr;
5646	int offset = skb->data - skb_mac_header(skb);
5647	int err;
5648
5649	if (WARN_ONCE(offset,
5650		      "__skb_vlan_pop got skb with skb->data not at mac header (offset %d)\n",
5651		      offset)) {
5652		return -EINVAL;
5653	}
5654
5655	err = skb_ensure_writable(skb, VLAN_ETH_HLEN);
5656	if (unlikely(err))
5657		return err;
5658
5659	skb_postpull_rcsum(skb, skb->data + (2 * ETH_ALEN), VLAN_HLEN);
5660
5661	vhdr = (struct vlan_hdr *)(skb->data + ETH_HLEN);
5662	*vlan_tci = ntohs(vhdr->h_vlan_TCI);
5663
5664	memmove(skb->data + VLAN_HLEN, skb->data, 2 * ETH_ALEN);
5665	__skb_pull(skb, VLAN_HLEN);
5666
5667	vlan_set_encap_proto(skb, vhdr);
5668	skb->mac_header += VLAN_HLEN;
5669
5670	if (skb_network_offset(skb) < ETH_HLEN)
5671		skb_set_network_header(skb, ETH_HLEN);
5672
5673	skb_reset_mac_len(skb);
5674
5675	return err;
5676}
5677EXPORT_SYMBOL(__skb_vlan_pop);
5678
5679/* Pop a vlan tag either from hwaccel or from payload.
5680 * Expects skb->data at mac header.
5681 */
5682int skb_vlan_pop(struct sk_buff *skb)
5683{
5684	u16 vlan_tci;
5685	__be16 vlan_proto;
5686	int err;
5687
5688	if (likely(skb_vlan_tag_present(skb))) {
5689		__vlan_hwaccel_clear_tag(skb);
5690	} else {
5691		if (unlikely(!eth_type_vlan(skb->protocol)))
5692			return 0;
5693
5694		err = __skb_vlan_pop(skb, &vlan_tci);
5695		if (err)
5696			return err;
5697	}
5698	/* move next vlan tag to hw accel tag */
5699	if (likely(!eth_type_vlan(skb->protocol)))
5700		return 0;
5701
5702	vlan_proto = skb->protocol;
5703	err = __skb_vlan_pop(skb, &vlan_tci);
5704	if (unlikely(err))
5705		return err;
5706
5707	__vlan_hwaccel_put_tag(skb, vlan_proto, vlan_tci);
5708	return 0;
5709}
5710EXPORT_SYMBOL(skb_vlan_pop);
5711
5712/* Push a vlan tag either into hwaccel or into payload (if hwaccel tag present).
5713 * Expects skb->data at mac header.
5714 */
5715int skb_vlan_push(struct sk_buff *skb, __be16 vlan_proto, u16 vlan_tci)
5716{
5717	if (skb_vlan_tag_present(skb)) {
5718		int offset = skb->data - skb_mac_header(skb);
5719		int err;
5720
5721		if (WARN_ONCE(offset,
5722			      "skb_vlan_push got skb with skb->data not at mac header (offset %d)\n",
5723			      offset)) {
5724			return -EINVAL;
5725		}
5726
5727		err = __vlan_insert_tag(skb, skb->vlan_proto,
5728					skb_vlan_tag_get(skb));
5729		if (err)
5730			return err;
5731
5732		skb->protocol = skb->vlan_proto;
5733		skb->mac_len += VLAN_HLEN;
5734
5735		skb_postpush_rcsum(skb, skb->data + (2 * ETH_ALEN), VLAN_HLEN);
5736	}
5737	__vlan_hwaccel_put_tag(skb, vlan_proto, vlan_tci);
5738	return 0;
5739}
5740EXPORT_SYMBOL(skb_vlan_push);
5741
5742/**
5743 * skb_eth_pop() - Drop the Ethernet header at the head of a packet
5744 *
5745 * @skb: Socket buffer to modify
5746 *
5747 * Drop the Ethernet header of @skb.
5748 *
5749 * Expects that skb->data points to the mac header and that no VLAN tags are
5750 * present.
5751 *
5752 * Returns 0 on success, -errno otherwise.
5753 */
5754int skb_eth_pop(struct sk_buff *skb)
5755{
5756	if (!pskb_may_pull(skb, ETH_HLEN) || skb_vlan_tagged(skb) ||
5757	    skb_network_offset(skb) < ETH_HLEN)
5758		return -EPROTO;
5759
5760	skb_pull_rcsum(skb, ETH_HLEN);
5761	skb_reset_mac_header(skb);
5762	skb_reset_mac_len(skb);
5763
5764	return 0;
5765}
5766EXPORT_SYMBOL(skb_eth_pop);
5767
5768/**
5769 * skb_eth_push() - Add a new Ethernet header at the head of a packet
5770 *
5771 * @skb: Socket buffer to modify
5772 * @dst: Destination MAC address of the new header
5773 * @src: Source MAC address of the new header
5774 *
5775 * Prepend @skb with a new Ethernet header.
5776 *
5777 * Expects that skb->data points to the mac header, which must be empty.
5778 *
5779 * Returns 0 on success, -errno otherwise.
5780 */
5781int skb_eth_push(struct sk_buff *skb, const unsigned char *dst,
5782		 const unsigned char *src)
5783{
5784	struct ethhdr *eth;
5785	int err;
5786
5787	if (skb_network_offset(skb) || skb_vlan_tag_present(skb))
5788		return -EPROTO;
5789
5790	err = skb_cow_head(skb, sizeof(*eth));
5791	if (err < 0)
5792		return err;
5793
5794	skb_push(skb, sizeof(*eth));
5795	skb_reset_mac_header(skb);
5796	skb_reset_mac_len(skb);
5797
5798	eth = eth_hdr(skb);
5799	ether_addr_copy(eth->h_dest, dst);
5800	ether_addr_copy(eth->h_source, src);
5801	eth->h_proto = skb->protocol;
5802
5803	skb_postpush_rcsum(skb, eth, sizeof(*eth));
5804
5805	return 0;
5806}
5807EXPORT_SYMBOL(skb_eth_push);
5808
5809/* Update the ethertype of hdr and the skb csum value if required. */
5810static void skb_mod_eth_type(struct sk_buff *skb, struct ethhdr *hdr,
5811			     __be16 ethertype)
5812{
5813	if (skb->ip_summed == CHECKSUM_COMPLETE) {
5814		__be16 diff[] = { ~hdr->h_proto, ethertype };
5815
5816		skb->csum = csum_partial((char *)diff, sizeof(diff), skb->csum);
5817	}
5818
5819	hdr->h_proto = ethertype;
5820}
5821
5822/**
5823 * skb_mpls_push() - push a new MPLS header after mac_len bytes from start of
5824 *                   the packet
5825 *
5826 * @skb: buffer
5827 * @mpls_lse: MPLS label stack entry to push
5828 * @mpls_proto: ethertype of the new MPLS header (expects 0x8847 or 0x8848)
5829 * @mac_len: length of the MAC header
5830 * @ethernet: flag to indicate if the resulting packet after skb_mpls_push is
5831 *            ethernet
5832 *
5833 * Expects skb->data at mac header.
5834 *
5835 * Returns 0 on success, -errno otherwise.
5836 */
5837int skb_mpls_push(struct sk_buff *skb, __be32 mpls_lse, __be16 mpls_proto,
5838		  int mac_len, bool ethernet)
5839{
5840	struct mpls_shim_hdr *lse;
5841	int err;
5842
5843	if (unlikely(!eth_p_mpls(mpls_proto)))
5844		return -EINVAL;
5845
5846	/* Networking stack does not allow simultaneous Tunnel and MPLS GSO. */
5847	if (skb->encapsulation)
5848		return -EINVAL;
5849
5850	err = skb_cow_head(skb, MPLS_HLEN);
5851	if (unlikely(err))
5852		return err;
5853
5854	if (!skb->inner_protocol) {
5855		skb_set_inner_network_header(skb, skb_network_offset(skb));
5856		skb_set_inner_protocol(skb, skb->protocol);
5857	}
5858
5859	skb_push(skb, MPLS_HLEN);
5860	memmove(skb_mac_header(skb) - MPLS_HLEN, skb_mac_header(skb),
5861		mac_len);
5862	skb_reset_mac_header(skb);
5863	skb_set_network_header(skb, mac_len);
5864	skb_reset_mac_len(skb);
5865
5866	lse = mpls_hdr(skb);
5867	lse->label_stack_entry = mpls_lse;
5868	skb_postpush_rcsum(skb, lse, MPLS_HLEN);
5869
5870	if (ethernet && mac_len >= ETH_HLEN)
5871		skb_mod_eth_type(skb, eth_hdr(skb), mpls_proto);
5872	skb->protocol = mpls_proto;
5873
5874	return 0;
5875}
5876EXPORT_SYMBOL_GPL(skb_mpls_push);
5877
5878/**
5879 * skb_mpls_pop() - pop the outermost MPLS header
5880 *
5881 * @skb: buffer
5882 * @next_proto: ethertype of header after popped MPLS header
5883 * @mac_len: length of the MAC header
5884 * @ethernet: flag to indicate if the packet is ethernet
5885 *
5886 * Expects skb->data at mac header.
5887 *
5888 * Returns 0 on success, -errno otherwise.
5889 */
5890int skb_mpls_pop(struct sk_buff *skb, __be16 next_proto, int mac_len,
5891		 bool ethernet)
5892{
5893	int err;
5894
5895	if (unlikely(!eth_p_mpls(skb->protocol)))
5896		return 0;
5897
5898	err = skb_ensure_writable(skb, mac_len + MPLS_HLEN);
5899	if (unlikely(err))
5900		return err;
5901
5902	skb_postpull_rcsum(skb, mpls_hdr(skb), MPLS_HLEN);
5903	memmove(skb_mac_header(skb) + MPLS_HLEN, skb_mac_header(skb),
5904		mac_len);
5905
5906	__skb_pull(skb, MPLS_HLEN);
5907	skb_reset_mac_header(skb);
5908	skb_set_network_header(skb, mac_len);
5909
5910	if (ethernet && mac_len >= ETH_HLEN) {
5911		struct ethhdr *hdr;
5912
5913		/* use mpls_hdr() to get ethertype to account for VLANs. */
5914		hdr = (struct ethhdr *)((void *)mpls_hdr(skb) - ETH_HLEN);
5915		skb_mod_eth_type(skb, hdr, next_proto);
5916	}
5917	skb->protocol = next_proto;
5918
5919	return 0;
5920}
5921EXPORT_SYMBOL_GPL(skb_mpls_pop);
5922
5923/**
5924 * skb_mpls_update_lse() - modify outermost MPLS header and update csum
5925 *
5926 * @skb: buffer
5927 * @mpls_lse: new MPLS label stack entry to update to
5928 *
5929 * Expects skb->data at mac header.
5930 *
5931 * Returns 0 on success, -errno otherwise.
5932 */
5933int skb_mpls_update_lse(struct sk_buff *skb, __be32 mpls_lse)
5934{
5935	int err;
5936
5937	if (unlikely(!eth_p_mpls(skb->protocol)))
5938		return -EINVAL;
5939
5940	err = skb_ensure_writable(skb, skb->mac_len + MPLS_HLEN);
5941	if (unlikely(err))
5942		return err;
5943
5944	if (skb->ip_summed == CHECKSUM_COMPLETE) {
5945		__be32 diff[] = { ~mpls_hdr(skb)->label_stack_entry, mpls_lse };
5946
5947		skb->csum = csum_partial((char *)diff, sizeof(diff), skb->csum);
5948	}
5949
5950	mpls_hdr(skb)->label_stack_entry = mpls_lse;
5951
5952	return 0;
5953}
5954EXPORT_SYMBOL_GPL(skb_mpls_update_lse);
5955
5956/**
5957 * skb_mpls_dec_ttl() - decrement the TTL of the outermost MPLS header
5958 *
5959 * @skb: buffer
5960 *
5961 * Expects skb->data at mac header.
5962 *
5963 * Returns 0 on success, -errno otherwise.
5964 */
5965int skb_mpls_dec_ttl(struct sk_buff *skb)
5966{
5967	u32 lse;
5968	u8 ttl;
5969
5970	if (unlikely(!eth_p_mpls(skb->protocol)))
5971		return -EINVAL;
5972
5973	if (!pskb_may_pull(skb, skb_network_offset(skb) + MPLS_HLEN))
5974		return -ENOMEM;
5975
5976	lse = be32_to_cpu(mpls_hdr(skb)->label_stack_entry);
5977	ttl = (lse & MPLS_LS_TTL_MASK) >> MPLS_LS_TTL_SHIFT;
5978	if (!--ttl)
5979		return -EINVAL;
5980
5981	lse &= ~MPLS_LS_TTL_MASK;
5982	lse |= ttl << MPLS_LS_TTL_SHIFT;
5983
5984	return skb_mpls_update_lse(skb, cpu_to_be32(lse));
5985}
5986EXPORT_SYMBOL_GPL(skb_mpls_dec_ttl);
5987
5988/**
5989 * alloc_skb_with_frags - allocate skb with page frags
5990 *
5991 * @header_len: size of linear part
5992 * @data_len: needed length in frags
5993 * @max_page_order: max page order desired.
5994 * @errcode: pointer to error code if any
5995 * @gfp_mask: allocation mask
5996 *
5997 * This can be used to allocate a paged skb, given a maximal order for frags.
5998 */
5999struct sk_buff *alloc_skb_with_frags(unsigned long header_len,
6000				     unsigned long data_len,
6001				     int max_page_order,
6002				     int *errcode,
6003				     gfp_t gfp_mask)
6004{
6005	int npages = (data_len + (PAGE_SIZE - 1)) >> PAGE_SHIFT;
6006	unsigned long chunk;
6007	struct sk_buff *skb;
6008	struct page *page;
6009	int i;
6010
6011	*errcode = -EMSGSIZE;
6012	/* Note this test could be relaxed, if we succeed to allocate
6013	 * high order pages...
6014	 */
6015	if (npages > MAX_SKB_FRAGS)
6016		return NULL;
6017
6018	*errcode = -ENOBUFS;
6019	skb = alloc_skb(header_len, gfp_mask);
6020	if (!skb)
6021		return NULL;
6022
6023	skb->truesize += npages << PAGE_SHIFT;
6024
6025	for (i = 0; npages > 0; i++) {
6026		int order = max_page_order;
6027
6028		while (order) {
6029			if (npages >= 1 << order) {
6030				page = alloc_pages((gfp_mask & ~__GFP_DIRECT_RECLAIM) |
6031						   __GFP_COMP |
6032						   __GFP_NOWARN,
6033						   order);
6034				if (page)
6035					goto fill_page;
6036				/* Do not retry other high order allocations */
6037				order = 1;
6038				max_page_order = 0;
6039			}
6040			order--;
6041		}
6042		page = alloc_page(gfp_mask);
6043		if (!page)
6044			goto failure;
6045fill_page:
6046		chunk = min_t(unsigned long, data_len,
6047			      PAGE_SIZE << order);
6048		skb_fill_page_desc(skb, i, page, 0, chunk);
6049		data_len -= chunk;
6050		npages -= 1 << order;
6051	}
6052	return skb;
6053
6054failure:
6055	kfree_skb(skb);
6056	return NULL;
6057}
6058EXPORT_SYMBOL(alloc_skb_with_frags);
6059
6060/* carve out the first off bytes from skb when off < headlen */
6061static int pskb_carve_inside_header(struct sk_buff *skb, const u32 off,
6062				    const int headlen, gfp_t gfp_mask)
6063{
6064	int i;
6065	int size = skb_end_offset(skb);
6066	int new_hlen = headlen - off;
6067	u8 *data;
6068
6069	size = SKB_DATA_ALIGN(size);
6070
6071	if (skb_pfmemalloc(skb))
6072		gfp_mask |= __GFP_MEMALLOC;
6073	data = kmalloc_reserve(size +
6074			       SKB_DATA_ALIGN(sizeof(struct skb_shared_info)),
6075			       gfp_mask, NUMA_NO_NODE, NULL);
6076	if (!data)
6077		return -ENOMEM;
6078
6079	size = SKB_WITH_OVERHEAD(ksize(data));
6080
6081	/* Copy real data, and all frags */
6082	skb_copy_from_linear_data_offset(skb, off, data, new_hlen);
6083	skb->len -= off;
6084
6085	memcpy((struct skb_shared_info *)(data + size),
6086	       skb_shinfo(skb),
6087	       offsetof(struct skb_shared_info,
6088			frags[skb_shinfo(skb)->nr_frags]));
6089	if (skb_cloned(skb)) {
6090		/* drop the old head gracefully */
6091		if (skb_orphan_frags(skb, gfp_mask)) {
6092			kfree(data);
6093			return -ENOMEM;
6094		}
6095		for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
6096			skb_frag_ref(skb, i);
6097		if (skb_has_frag_list(skb))
6098			skb_clone_fraglist(skb);
6099		skb_release_data(skb);
6100	} else {
6101		/* we can reuse existing recount- all we did was
6102		 * relocate values
6103		 */
6104		skb_free_head(skb);
6105	}
6106
6107	skb->head = data;
6108	skb->data = data;
6109	skb->head_frag = 0;
6110#ifdef NET_SKBUFF_DATA_USES_OFFSET
6111	skb->end = size;
6112#else
6113	skb->end = skb->head + size;
6114#endif
6115	skb_set_tail_pointer(skb, skb_headlen(skb));
6116	skb_headers_offset_update(skb, 0);
6117	skb->cloned = 0;
6118	skb->hdr_len = 0;
6119	skb->nohdr = 0;
6120	atomic_set(&skb_shinfo(skb)->dataref, 1);
6121
6122	return 0;
6123}
6124
6125static int pskb_carve(struct sk_buff *skb, const u32 off, gfp_t gfp);
6126
6127/* carve out the first eat bytes from skb's frag_list. May recurse into
6128 * pskb_carve()
6129 */
6130static int pskb_carve_frag_list(struct sk_buff *skb,
6131				struct skb_shared_info *shinfo, int eat,
6132				gfp_t gfp_mask)
6133{
6134	struct sk_buff *list = shinfo->frag_list;
6135	struct sk_buff *clone = NULL;
6136	struct sk_buff *insp = NULL;
6137
6138	do {
6139		if (!list) {
6140			pr_err("Not enough bytes to eat. Want %d\n", eat);
6141			return -EFAULT;
6142		}
6143		if (list->len <= eat) {
6144			/* Eaten as whole. */
6145			eat -= list->len;
6146			list = list->next;
6147			insp = list;
6148		} else {
6149			/* Eaten partially. */
6150			if (skb_shared(list)) {
6151				clone = skb_clone(list, gfp_mask);
6152				if (!clone)
6153					return -ENOMEM;
6154				insp = list->next;
6155				list = clone;
6156			} else {
6157				/* This may be pulled without problems. */
6158				insp = list;
6159			}
6160			if (pskb_carve(list, eat, gfp_mask) < 0) {
6161				kfree_skb(clone);
6162				return -ENOMEM;
6163			}
6164			break;
6165		}
6166	} while (eat);
6167
6168	/* Free pulled out fragments. */
6169	while ((list = shinfo->frag_list) != insp) {
6170		shinfo->frag_list = list->next;
6171		kfree_skb(list);
6172	}
6173	/* And insert new clone at head. */
6174	if (clone) {
6175		clone->next = list;
6176		shinfo->frag_list = clone;
6177	}
6178	return 0;
6179}
6180
6181/* carve off first len bytes from skb. Split line (off) is in the
6182 * non-linear part of skb
6183 */
6184static int pskb_carve_inside_nonlinear(struct sk_buff *skb, const u32 off,
6185				       int pos, gfp_t gfp_mask)
6186{
6187	int i, k = 0;
6188	int size = skb_end_offset(skb);
6189	u8 *data;
6190	const int nfrags = skb_shinfo(skb)->nr_frags;
6191	struct skb_shared_info *shinfo;
6192
6193	size = SKB_DATA_ALIGN(size);
6194
6195	if (skb_pfmemalloc(skb))
6196		gfp_mask |= __GFP_MEMALLOC;
6197	data = kmalloc_reserve(size +
6198			       SKB_DATA_ALIGN(sizeof(struct skb_shared_info)),
6199			       gfp_mask, NUMA_NO_NODE, NULL);
6200	if (!data)
6201		return -ENOMEM;
6202
6203	size = SKB_WITH_OVERHEAD(ksize(data));
6204
6205	memcpy((struct skb_shared_info *)(data + size),
6206	       skb_shinfo(skb), offsetof(struct skb_shared_info, frags[0]));
 
6207	if (skb_orphan_frags(skb, gfp_mask)) {
6208		kfree(data);
6209		return -ENOMEM;
6210	}
6211	shinfo = (struct skb_shared_info *)(data + size);
6212	for (i = 0; i < nfrags; i++) {
6213		int fsize = skb_frag_size(&skb_shinfo(skb)->frags[i]);
6214
6215		if (pos + fsize > off) {
6216			shinfo->frags[k] = skb_shinfo(skb)->frags[i];
6217
6218			if (pos < off) {
6219				/* Split frag.
6220				 * We have two variants in this case:
6221				 * 1. Move all the frag to the second
6222				 *    part, if it is possible. F.e.
6223				 *    this approach is mandatory for TUX,
6224				 *    where splitting is expensive.
6225				 * 2. Split is accurately. We make this.
6226				 */
6227				skb_frag_off_add(&shinfo->frags[0], off - pos);
6228				skb_frag_size_sub(&shinfo->frags[0], off - pos);
6229			}
6230			skb_frag_ref(skb, i);
6231			k++;
6232		}
6233		pos += fsize;
6234	}
6235	shinfo->nr_frags = k;
6236	if (skb_has_frag_list(skb))
6237		skb_clone_fraglist(skb);
6238
6239	/* split line is in frag list */
6240	if (k == 0 && pskb_carve_frag_list(skb, shinfo, off - pos, gfp_mask)) {
6241		/* skb_frag_unref() is not needed here as shinfo->nr_frags = 0. */
6242		if (skb_has_frag_list(skb))
6243			kfree_skb_list(skb_shinfo(skb)->frag_list);
6244		kfree(data);
6245		return -ENOMEM;
6246	}
6247	skb_release_data(skb);
6248
6249	skb->head = data;
6250	skb->head_frag = 0;
6251	skb->data = data;
6252#ifdef NET_SKBUFF_DATA_USES_OFFSET
6253	skb->end = size;
6254#else
6255	skb->end = skb->head + size;
6256#endif
6257	skb_reset_tail_pointer(skb);
6258	skb_headers_offset_update(skb, 0);
6259	skb->cloned   = 0;
6260	skb->hdr_len  = 0;
6261	skb->nohdr    = 0;
6262	skb->len -= off;
6263	skb->data_len = skb->len;
6264	atomic_set(&skb_shinfo(skb)->dataref, 1);
6265	return 0;
6266}
6267
6268/* remove len bytes from the beginning of the skb */
6269static int pskb_carve(struct sk_buff *skb, const u32 len, gfp_t gfp)
6270{
6271	int headlen = skb_headlen(skb);
6272
6273	if (len < headlen)
6274		return pskb_carve_inside_header(skb, len, headlen, gfp);
6275	else
6276		return pskb_carve_inside_nonlinear(skb, len, headlen, gfp);
6277}
6278
6279/* Extract to_copy bytes starting at off from skb, and return this in
6280 * a new skb
6281 */
6282struct sk_buff *pskb_extract(struct sk_buff *skb, int off,
6283			     int to_copy, gfp_t gfp)
6284{
6285	struct sk_buff  *clone = skb_clone(skb, gfp);
6286
6287	if (!clone)
6288		return NULL;
6289
6290	if (pskb_carve(clone, off, gfp) < 0 ||
6291	    pskb_trim(clone, to_copy)) {
6292		kfree_skb(clone);
6293		return NULL;
6294	}
6295	return clone;
6296}
6297EXPORT_SYMBOL(pskb_extract);
6298
6299/**
6300 * skb_condense - try to get rid of fragments/frag_list if possible
6301 * @skb: buffer
6302 *
6303 * Can be used to save memory before skb is added to a busy queue.
6304 * If packet has bytes in frags and enough tail room in skb->head,
6305 * pull all of them, so that we can free the frags right now and adjust
6306 * truesize.
6307 * Notes:
6308 *	We do not reallocate skb->head thus can not fail.
6309 *	Caller must re-evaluate skb->truesize if needed.
6310 */
6311void skb_condense(struct sk_buff *skb)
6312{
6313	if (skb->data_len) {
6314		if (skb->data_len > skb->end - skb->tail ||
6315		    skb_cloned(skb))
6316			return;
6317
6318		/* Nice, we can free page frag(s) right now */
6319		__pskb_pull_tail(skb, skb->data_len);
6320	}
6321	/* At this point, skb->truesize might be over estimated,
6322	 * because skb had a fragment, and fragments do not tell
6323	 * their truesize.
6324	 * When we pulled its content into skb->head, fragment
6325	 * was freed, but __pskb_pull_tail() could not possibly
6326	 * adjust skb->truesize, not knowing the frag truesize.
6327	 */
6328	skb->truesize = SKB_TRUESIZE(skb_end_offset(skb));
6329}
6330
6331#ifdef CONFIG_SKB_EXTENSIONS
6332static void *skb_ext_get_ptr(struct skb_ext *ext, enum skb_ext_id id)
6333{
6334	return (void *)ext + (ext->offset[id] * SKB_EXT_ALIGN_VALUE);
6335}
6336
6337/**
6338 * __skb_ext_alloc - allocate a new skb extensions storage
6339 *
6340 * @flags: See kmalloc().
6341 *
6342 * Returns the newly allocated pointer. The pointer can later attached to a
6343 * skb via __skb_ext_set().
6344 * Note: caller must handle the skb_ext as an opaque data.
6345 */
6346struct skb_ext *__skb_ext_alloc(gfp_t flags)
6347{
6348	struct skb_ext *new = kmem_cache_alloc(skbuff_ext_cache, flags);
6349
6350	if (new) {
6351		memset(new->offset, 0, sizeof(new->offset));
6352		refcount_set(&new->refcnt, 1);
6353	}
6354
6355	return new;
6356}
6357
6358static struct skb_ext *skb_ext_maybe_cow(struct skb_ext *old,
6359					 unsigned int old_active)
6360{
6361	struct skb_ext *new;
6362
6363	if (refcount_read(&old->refcnt) == 1)
6364		return old;
6365
6366	new = kmem_cache_alloc(skbuff_ext_cache, GFP_ATOMIC);
6367	if (!new)
6368		return NULL;
6369
6370	memcpy(new, old, old->chunks * SKB_EXT_ALIGN_VALUE);
6371	refcount_set(&new->refcnt, 1);
6372
6373#ifdef CONFIG_XFRM
6374	if (old_active & (1 << SKB_EXT_SEC_PATH)) {
6375		struct sec_path *sp = skb_ext_get_ptr(old, SKB_EXT_SEC_PATH);
6376		unsigned int i;
6377
6378		for (i = 0; i < sp->len; i++)
6379			xfrm_state_hold(sp->xvec[i]);
6380	}
6381#endif
6382	__skb_ext_put(old);
6383	return new;
6384}
6385
6386/**
6387 * __skb_ext_set - attach the specified extension storage to this skb
6388 * @skb: buffer
6389 * @id: extension id
6390 * @ext: extension storage previously allocated via __skb_ext_alloc()
6391 *
6392 * Existing extensions, if any, are cleared.
6393 *
6394 * Returns the pointer to the extension.
6395 */
6396void *__skb_ext_set(struct sk_buff *skb, enum skb_ext_id id,
6397		    struct skb_ext *ext)
6398{
6399	unsigned int newlen, newoff = SKB_EXT_CHUNKSIZEOF(*ext);
6400
6401	skb_ext_put(skb);
6402	newlen = newoff + skb_ext_type_len[id];
6403	ext->chunks = newlen;
6404	ext->offset[id] = newoff;
6405	skb->extensions = ext;
6406	skb->active_extensions = 1 << id;
6407	return skb_ext_get_ptr(ext, id);
6408}
6409
6410/**
6411 * skb_ext_add - allocate space for given extension, COW if needed
6412 * @skb: buffer
6413 * @id: extension to allocate space for
6414 *
6415 * Allocates enough space for the given extension.
6416 * If the extension is already present, a pointer to that extension
6417 * is returned.
6418 *
6419 * If the skb was cloned, COW applies and the returned memory can be
6420 * modified without changing the extension space of clones buffers.
6421 *
6422 * Returns pointer to the extension or NULL on allocation failure.
6423 */
6424void *skb_ext_add(struct sk_buff *skb, enum skb_ext_id id)
6425{
6426	struct skb_ext *new, *old = NULL;
6427	unsigned int newlen, newoff;
6428
6429	if (skb->active_extensions) {
6430		old = skb->extensions;
6431
6432		new = skb_ext_maybe_cow(old, skb->active_extensions);
6433		if (!new)
6434			return NULL;
6435
6436		if (__skb_ext_exist(new, id))
6437			goto set_active;
6438
6439		newoff = new->chunks;
6440	} else {
6441		newoff = SKB_EXT_CHUNKSIZEOF(*new);
6442
6443		new = __skb_ext_alloc(GFP_ATOMIC);
6444		if (!new)
6445			return NULL;
6446	}
6447
6448	newlen = newoff + skb_ext_type_len[id];
6449	new->chunks = newlen;
6450	new->offset[id] = newoff;
6451set_active:
6452	skb->extensions = new;
6453	skb->active_extensions |= 1 << id;
6454	return skb_ext_get_ptr(new, id);
6455}
6456EXPORT_SYMBOL(skb_ext_add);
6457
6458#ifdef CONFIG_XFRM
6459static void skb_ext_put_sp(struct sec_path *sp)
6460{
6461	unsigned int i;
6462
6463	for (i = 0; i < sp->len; i++)
6464		xfrm_state_put(sp->xvec[i]);
6465}
6466#endif
6467
6468void __skb_ext_del(struct sk_buff *skb, enum skb_ext_id id)
6469{
6470	struct skb_ext *ext = skb->extensions;
6471
6472	skb->active_extensions &= ~(1 << id);
6473	if (skb->active_extensions == 0) {
6474		skb->extensions = NULL;
6475		__skb_ext_put(ext);
6476#ifdef CONFIG_XFRM
6477	} else if (id == SKB_EXT_SEC_PATH &&
6478		   refcount_read(&ext->refcnt) == 1) {
6479		struct sec_path *sp = skb_ext_get_ptr(ext, SKB_EXT_SEC_PATH);
6480
6481		skb_ext_put_sp(sp);
6482		sp->len = 0;
6483#endif
6484	}
6485}
6486EXPORT_SYMBOL(__skb_ext_del);
6487
6488void __skb_ext_put(struct skb_ext *ext)
6489{
6490	/* If this is last clone, nothing can increment
6491	 * it after check passes.  Avoids one atomic op.
6492	 */
6493	if (refcount_read(&ext->refcnt) == 1)
6494		goto free_now;
6495
6496	if (!refcount_dec_and_test(&ext->refcnt))
6497		return;
6498free_now:
6499#ifdef CONFIG_XFRM
6500	if (__skb_ext_exist(ext, SKB_EXT_SEC_PATH))
6501		skb_ext_put_sp(skb_ext_get_ptr(ext, SKB_EXT_SEC_PATH));
6502#endif
6503
6504	kmem_cache_free(skbuff_ext_cache, ext);
6505}
6506EXPORT_SYMBOL(__skb_ext_put);
6507#endif /* CONFIG_SKB_EXTENSIONS */