1/*
   2 *	Routines having to do with the 'struct sk_buff' memory handlers.
   3 *
   4 *	Authors:	Alan Cox <alan@lxorguk.ukuu.org.uk>
   5 *			Florian La Roche <rzsfl@rz.uni-sb.de>
   6 *
   7 *	Fixes:
   8 *		Alan Cox	:	Fixed the worst of the load
   9 *					balancer bugs.
  10 *		Dave Platt	:	Interrupt stacking fix.
  11 *	Richard Kooijman	:	Timestamp fixes.
  12 *		Alan Cox	:	Changed buffer format.
  13 *		Alan Cox	:	destructor hook for AF_UNIX etc.
  14 *		Linus Torvalds	:	Better skb_clone.
  15 *		Alan Cox	:	Added skb_copy.
  16 *		Alan Cox	:	Added all the changed routines Linus
  17 *					only put in the headers
  18 *		Ray VanTassle	:	Fixed --skb->lock in free
  19 *		Alan Cox	:	skb_copy copy arp field
  20 *		Andi Kleen	:	slabified it.
  21 *		Robert Olsson	:	Removed skb_head_pool
  22 *
  23 *	NOTE:
  24 *		The __skb_ routines should be called with interrupts
  25 *	disabled, or you better be *real* sure that the operation is atomic
  26 *	with respect to whatever list is being frobbed (e.g. via lock_sock()
  27 *	or via disabling bottom half handlers, etc).
  28 *
  29 *	This program is free software; you can redistribute it and/or
  30 *	modify it under the terms of the GNU General Public License
  31 *	as published by the Free Software Foundation; either version
  32 *	2 of the License, or (at your option) any later version.
  33 */
  34
  35/*
  36 *	The functions in this file will not compile correctly with gcc 2.4.x
  37 */
  38
  39#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  40
  41#include <linux/module.h>
  42#include <linux/types.h>
  43#include <linux/kernel.h>
  44#include <linux/kmemcheck.h>
  45#include <linux/mm.h>
  46#include <linux/interrupt.h>
  47#include <linux/in.h>
  48#include <linux/inet.h>
  49#include <linux/slab.h>
  50#include <linux/tcp.h>
  51#include <linux/udp.h>
  52#include <linux/netdevice.h>
  53#ifdef CONFIG_NET_CLS_ACT
  54#include <net/pkt_sched.h>
  55#endif
  56#include <linux/string.h>
  57#include <linux/skbuff.h>
  58#include <linux/splice.h>
  59#include <linux/cache.h>
  60#include <linux/rtnetlink.h>
  61#include <linux/init.h>
  62#include <linux/scatterlist.h>
  63#include <linux/errqueue.h>
  64#include <linux/prefetch.h>
  65
  66#include <net/protocol.h>
  67#include <net/dst.h>
  68#include <net/sock.h>
  69#include <net/checksum.h>
  70#include <net/ip6_checksum.h>
  71#include <net/xfrm.h>
  72
  73#include <asm/uaccess.h>
  74#include <trace/events/skb.h>
  75#include <linux/highmem.h>
  76
  77struct kmem_cache *skbuff_head_cache __read_mostly;
  78static struct kmem_cache *skbuff_fclone_cache __read_mostly;
  79
  80/**
  81 *	skb_panic - private function for out-of-line support
  82 *	@skb:	buffer
  83 *	@sz:	size
  84 *	@addr:	address
  85 *	@msg:	skb_over_panic or skb_under_panic
  86 *
  87 *	Out-of-line support for skb_put() and skb_push().
  88 *	Called via the wrapper skb_over_panic() or skb_under_panic().
  89 *	Keep out of line to prevent kernel bloat.
  90 *	__builtin_return_address is not used because it is not always reliable.
  91 */
  92static void skb_panic(struct sk_buff *skb, unsigned int sz, void *addr,
  93		      const char msg[])
  94{
  95	pr_emerg("%s: text:%p len:%d put:%d head:%p data:%p tail:%#lx end:%#lx dev:%s\n",
  96		 msg, addr, skb->len, sz, skb->head, skb->data,
  97		 (unsigned long)skb->tail, (unsigned long)skb->end,
  98		 skb->dev ? skb->dev->name : "<NULL>");
  99	BUG();
 100}
 101
 102static void skb_over_panic(struct sk_buff *skb, unsigned int sz, void *addr)
 
 103{
 104	skb_panic(skb, sz, addr, __func__);
 105}
 106
 107static void skb_under_panic(struct sk_buff *skb, unsigned int sz, void *addr)
 
 108{
 109	skb_panic(skb, sz, addr, __func__);
 110}
 111
 
 
 
 
 
 
 
 
 
 
 
 
 112/*
 113 * kmalloc_reserve is a wrapper around kmalloc_node_track_caller that tells
 114 * the caller if emergency pfmemalloc reserves are being used. If it is and
 115 * the socket is later found to be SOCK_MEMALLOC then PFMEMALLOC reserves
 116 * may be used. Otherwise, the packet data may be discarded until enough
 117 * memory is free
 118 */
 119#define kmalloc_reserve(size, gfp, node, pfmemalloc) \
 120	 __kmalloc_reserve(size, gfp, node, _RET_IP_, pfmemalloc)
 121
 122static void *__kmalloc_reserve(size_t size, gfp_t flags, int node,
 123			       unsigned long ip, bool *pfmemalloc)
 
 
 
 
 
 
 
 124{
 125	void *obj;
 126	bool ret_pfmemalloc = false;
 127
 128	/*
 129	 * Try a regular allocation, when that fails and we're not entitled
 130	 * to the reserves, fail.
 131	 */
 132	obj = kmalloc_node_track_caller(size,
 133					flags | __GFP_NOMEMALLOC | __GFP_NOWARN,
 134					node);
 135	if (obj || !(gfp_pfmemalloc_allowed(flags)))
 136		goto out;
 137
 138	/* Try again but now we are using pfmemalloc reserves */
 139	ret_pfmemalloc = true;
 140	obj = kmalloc_node_track_caller(size, flags, node);
 141
 142out:
 143	if (pfmemalloc)
 144		*pfmemalloc = ret_pfmemalloc;
 
 
 
 
 
 145
 146	return obj;
 
 
 
 
 
 
 147}
 148
 149/* 	Allocate a new skbuff. We do this ourselves so we can fill in a few
 150 *	'private' fields and also do memory statistics to find all the
 151 *	[BEEP] leaks.
 152 *
 153 */
 154
 155struct sk_buff *__alloc_skb_head(gfp_t gfp_mask, int node)
 156{
 157	struct sk_buff *skb;
 158
 159	/* Get the HEAD */
 160	skb = kmem_cache_alloc_node(skbuff_head_cache,
 161				    gfp_mask & ~__GFP_DMA, node);
 162	if (!skb)
 163		goto out;
 164
 165	/*
 166	 * Only clear those fields we need to clear, not those that we will
 167	 * actually initialise below. Hence, don't put any more fields after
 168	 * the tail pointer in struct sk_buff!
 169	 */
 170	memset(skb, 0, offsetof(struct sk_buff, tail));
 171	skb->head = NULL;
 172	skb->truesize = sizeof(struct sk_buff);
 173	atomic_set(&skb->users, 1);
 174
 175	skb->mac_header = (typeof(skb->mac_header))~0U;
 176out:
 177	return skb;
 178}
 179
 180/**
 181 *	__alloc_skb	-	allocate a network buffer
 182 *	@size: size to allocate
 183 *	@gfp_mask: allocation mask
 184 *	@flags: If SKB_ALLOC_FCLONE is set, allocate from fclone cache
 185 *		instead of head cache and allocate a cloned (child) skb.
 186 *		If SKB_ALLOC_RX is set, __GFP_MEMALLOC will be used for
 187 *		allocations in case the data is required for writeback
 188 *	@node: numa node to allocate memory on
 189 *
 190 *	Allocate a new &sk_buff. The returned buffer has no headroom and a
 191 *	tail room of at least size bytes. The object has a reference count
 192 *	of one. The return is the buffer. On a failure the return is %NULL.
 193 *
 194 *	Buffers may only be allocated from interrupts using a @gfp_mask of
 195 *	%GFP_ATOMIC.
 196 */
 197struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
 198			    int flags, int node)
 199{
 200	struct kmem_cache *cache;
 201	struct skb_shared_info *shinfo;
 202	struct sk_buff *skb;
 203	u8 *data;
 204	bool pfmemalloc;
 205
 206	cache = (flags & SKB_ALLOC_FCLONE)
 207		? skbuff_fclone_cache : skbuff_head_cache;
 208
 209	if (sk_memalloc_socks() && (flags & SKB_ALLOC_RX))
 210		gfp_mask |= __GFP_MEMALLOC;
 211
 212	/* Get the HEAD */
 213	skb = kmem_cache_alloc_node(cache, gfp_mask & ~__GFP_DMA, node);
 214	if (!skb)
 215		goto out;
 216	prefetchw(skb);
 217
 218	/* We do our best to align skb_shared_info on a separate cache
 219	 * line. It usually works because kmalloc(X > SMP_CACHE_BYTES) gives
 220	 * aligned memory blocks, unless SLUB/SLAB debug is enabled.
 221	 * Both skb->head and skb_shared_info are cache line aligned.
 222	 */
 223	size = SKB_DATA_ALIGN(size);
 224	size += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
 225	data = kmalloc_reserve(size, gfp_mask, node, &pfmemalloc);
 226	if (!data)
 227		goto nodata;
 228	/* kmalloc(size) might give us more room than requested.
 229	 * Put skb_shared_info exactly at the end of allocated zone,
 230	 * to allow max possible filling before reallocation.
 231	 */
 232	size = SKB_WITH_OVERHEAD(ksize(data));
 233	prefetchw(data + size);
 234
 235	/*
 236	 * Only clear those fields we need to clear, not those that we will
 237	 * actually initialise below. Hence, don't put any more fields after
 238	 * the tail pointer in struct sk_buff!
 239	 */
 240	memset(skb, 0, offsetof(struct sk_buff, tail));
 241	/* Account for allocated memory : skb + skb->head */
 242	skb->truesize = SKB_TRUESIZE(size);
 243	skb->pfmemalloc = pfmemalloc;
 244	atomic_set(&skb->users, 1);
 245	skb->head = data;
 246	skb->data = data;
 247	skb_reset_tail_pointer(skb);
 248	skb->end = skb->tail + size;
 249	skb->mac_header = (typeof(skb->mac_header))~0U;
 250	skb->transport_header = (typeof(skb->transport_header))~0U;
 
 251
 252	/* make sure we initialize shinfo sequentially */
 253	shinfo = skb_shinfo(skb);
 254	memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
 255	atomic_set(&shinfo->dataref, 1);
 256	kmemcheck_annotate_variable(shinfo->destructor_arg);
 257
 258	if (flags & SKB_ALLOC_FCLONE) {
 259		struct sk_buff *child = skb + 1;
 260		atomic_t *fclone_ref = (atomic_t *) (child + 1);
 261
 262		kmemcheck_annotate_bitfield(child, flags1);
 263		kmemcheck_annotate_bitfield(child, flags2);
 264		skb->fclone = SKB_FCLONE_ORIG;
 265		atomic_set(fclone_ref, 1);
 266
 267		child->fclone = SKB_FCLONE_UNAVAILABLE;
 268		child->pfmemalloc = pfmemalloc;
 269	}
 270out:
 271	return skb;
 272nodata:
 273	kmem_cache_free(cache, skb);
 274	skb = NULL;
 275	goto out;
 276}
 277EXPORT_SYMBOL(__alloc_skb);
 278
 279/**
 280 * build_skb - build a network buffer
 281 * @data: data buffer provided by caller
 282 * @frag_size: size of fragment, or 0 if head was kmalloced
 283 *
 284 * Allocate a new &sk_buff. Caller provides space holding head and
 285 * skb_shared_info. @data must have been allocated by kmalloc() only if
 286 * @frag_size is 0, otherwise data should come from the page allocator.
 287 * The return is the new skb buffer.
 288 * On a failure the return is %NULL, and @data is not freed.
 289 * Notes :
 290 *  Before IO, driver allocates only data buffer where NIC put incoming frame
 291 *  Driver should add room at head (NET_SKB_PAD) and
 292 *  MUST add room at tail (SKB_DATA_ALIGN(skb_shared_info))
 293 *  After IO, driver calls build_skb(), to allocate sk_buff and populate it
 294 *  before giving packet to stack.
 295 *  RX rings only contains data buffers, not full skbs.
 296 */
 297struct sk_buff *build_skb(void *data, unsigned int frag_size)
 298{
 299	struct skb_shared_info *shinfo;
 300	struct sk_buff *skb;
 301	unsigned int size = frag_size ? : ksize(data);
 302
 303	skb = kmem_cache_alloc(skbuff_head_cache, GFP_ATOMIC);
 304	if (!skb)
 305		return NULL;
 306
 307	size -= SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
 308
 309	memset(skb, 0, offsetof(struct sk_buff, tail));
 310	skb->truesize = SKB_TRUESIZE(size);
 311	skb->head_frag = frag_size != 0;
 312	atomic_set(&skb->users, 1);
 313	skb->head = data;
 314	skb->data = data;
 315	skb_reset_tail_pointer(skb);
 316	skb->end = skb->tail + size;
 317	skb->mac_header = (typeof(skb->mac_header))~0U;
 318	skb->transport_header = (typeof(skb->transport_header))~0U;
 
 319
 320	/* make sure we initialize shinfo sequentially */
 321	shinfo = skb_shinfo(skb);
 322	memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
 323	atomic_set(&shinfo->dataref, 1);
 324	kmemcheck_annotate_variable(shinfo->destructor_arg);
 325
 326	return skb;
 327}
 328EXPORT_SYMBOL(build_skb);
 329
 330struct netdev_alloc_cache {
 331	struct page_frag	frag;
 332	/* we maintain a pagecount bias, so that we dont dirty cache line
 333	 * containing page->_count every time we allocate a fragment.
 334	 */
 335	unsigned int		pagecnt_bias;
 336};
 337static DEFINE_PER_CPU(struct netdev_alloc_cache, netdev_alloc_cache);
 338
 339static void *__netdev_alloc_frag(unsigned int fragsz, gfp_t gfp_mask)
 
 
 
 
 
 
 
 340{
 341	struct netdev_alloc_cache *nc;
 342	void *data = NULL;
 343	int order;
 344	unsigned long flags;
 345
 346	local_irq_save(flags);
 347	nc = &__get_cpu_var(netdev_alloc_cache);
 348	if (unlikely(!nc->frag.page)) {
 349refill:
 350		for (order = NETDEV_FRAG_PAGE_MAX_ORDER; ;) {
 351			gfp_t gfp = gfp_mask;
 352
 353			if (order)
 354				gfp |= __GFP_COMP | __GFP_NOWARN;
 355			nc->frag.page = alloc_pages(gfp, order);
 356			if (likely(nc->frag.page))
 357				break;
 358			if (--order < 0)
 359				goto end;
 360		}
 361		nc->frag.size = PAGE_SIZE << order;
 362recycle:
 363		atomic_set(&nc->frag.page->_count, NETDEV_PAGECNT_MAX_BIAS);
 364		nc->pagecnt_bias = NETDEV_PAGECNT_MAX_BIAS;
 365		nc->frag.offset = 0;
 366	}
 367
 368	if (nc->frag.offset + fragsz > nc->frag.size) {
 369		/* avoid unnecessary locked operations if possible */
 370		if ((atomic_read(&nc->frag.page->_count) == nc->pagecnt_bias) ||
 371		    atomic_sub_and_test(nc->pagecnt_bias, &nc->frag.page->_count))
 372			goto recycle;
 373		goto refill;
 374	}
 375
 376	data = page_address(nc->frag.page) + nc->frag.offset;
 377	nc->frag.offset += fragsz;
 378	nc->pagecnt_bias--;
 379end:
 380	local_irq_restore(flags);
 381	return data;
 382}
 383
 384/**
 385 * netdev_alloc_frag - allocate a page fragment
 386 * @fragsz: fragment size
 387 *
 388 * Allocates a frag from a page for receive buffer.
 389 * Uses GFP_ATOMIC allocations.
 390 */
 391void *netdev_alloc_frag(unsigned int fragsz)
 392{
 393	return __netdev_alloc_frag(fragsz, GFP_ATOMIC | __GFP_COLD);
 394}
 395EXPORT_SYMBOL(netdev_alloc_frag);
 396
 397/**
 398 *	__netdev_alloc_skb - allocate an skbuff for rx on a specific device
 399 *	@dev: network device to receive on
 400 *	@length: length to allocate
 401 *	@gfp_mask: get_free_pages mask, passed to alloc_skb
 402 *
 403 *	Allocate a new &sk_buff and assign it a usage count of one. The
 404 *	buffer has unspecified headroom built in. Users should allocate
 405 *	the headroom they think they need without accounting for the
 406 *	built in space. The built in space is used for optimisations.
 407 *
 408 *	%NULL is returned if there is no free memory.
 409 */
 410struct sk_buff *__netdev_alloc_skb(struct net_device *dev,
 411				   unsigned int length, gfp_t gfp_mask)
 412{
 413	struct sk_buff *skb = NULL;
 414	unsigned int fragsz = SKB_DATA_ALIGN(length + NET_SKB_PAD) +
 415			      SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
 416
 417	if (fragsz <= PAGE_SIZE && !(gfp_mask & (__GFP_WAIT | GFP_DMA))) {
 418		void *data;
 419
 420		if (sk_memalloc_socks())
 421			gfp_mask |= __GFP_MEMALLOC;
 422
 423		data = __netdev_alloc_frag(fragsz, gfp_mask);
 424
 425		if (likely(data)) {
 426			skb = build_skb(data, fragsz);
 427			if (unlikely(!skb))
 428				put_page(virt_to_head_page(data));
 429		}
 430	} else {
 431		skb = __alloc_skb(length + NET_SKB_PAD, gfp_mask,
 432				  SKB_ALLOC_RX, NUMA_NO_NODE);
 433	}
 434	if (likely(skb)) {
 435		skb_reserve(skb, NET_SKB_PAD);
 436		skb->dev = dev;
 437	}
 438	return skb;
 439}
 440EXPORT_SYMBOL(__netdev_alloc_skb);
 441
 442void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page, int off,
 443		     int size, unsigned int truesize)
 444{
 445	skb_fill_page_desc(skb, i, page, off, size);
 446	skb->len += size;
 447	skb->data_len += size;
 448	skb->truesize += truesize;
 449}
 450EXPORT_SYMBOL(skb_add_rx_frag);
 451
 452void skb_coalesce_rx_frag(struct sk_buff *skb, int i, int size,
 453			  unsigned int truesize)
 454{
 455	skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
 456
 457	skb_frag_size_add(frag, size);
 458	skb->len += size;
 459	skb->data_len += size;
 460	skb->truesize += truesize;
 461}
 462EXPORT_SYMBOL(skb_coalesce_rx_frag);
 463
 464static void skb_drop_list(struct sk_buff **listp)
 465{
 466	kfree_skb_list(*listp);
 
 467	*listp = NULL;
 
 
 
 
 
 
 468}
 469
 470static inline void skb_drop_fraglist(struct sk_buff *skb)
 471{
 472	skb_drop_list(&skb_shinfo(skb)->frag_list);
 473}
 474
 475static void skb_clone_fraglist(struct sk_buff *skb)
 476{
 477	struct sk_buff *list;
 478
 479	skb_walk_frags(skb, list)
 480		skb_get(list);
 481}
 482
 483static void skb_free_head(struct sk_buff *skb)
 484{
 485	if (skb->head_frag)
 486		put_page(virt_to_head_page(skb->head));
 487	else
 488		kfree(skb->head);
 489}
 490
 491static void skb_release_data(struct sk_buff *skb)
 492{
 493	if (!skb->cloned ||
 494	    !atomic_sub_return(skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1,
 495			       &skb_shinfo(skb)->dataref)) {
 496		if (skb_shinfo(skb)->nr_frags) {
 497			int i;
 498			for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
 499				skb_frag_unref(skb, i);
 500		}
 501
 502		/*
 503		 * If skb buf is from userspace, we need to notify the caller
 504		 * the lower device DMA has done;
 505		 */
 506		if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY) {
 507			struct ubuf_info *uarg;
 508
 509			uarg = skb_shinfo(skb)->destructor_arg;
 510			if (uarg->callback)
 511				uarg->callback(uarg, true);
 512		}
 513
 514		if (skb_has_frag_list(skb))
 515			skb_drop_fraglist(skb);
 516
 517		skb_free_head(skb);
 518	}
 519}
 520
 521/*
 522 *	Free an skbuff by memory without cleaning the state.
 523 */
 524static void kfree_skbmem(struct sk_buff *skb)
 525{
 526	struct sk_buff *other;
 527	atomic_t *fclone_ref;
 528
 529	switch (skb->fclone) {
 530	case SKB_FCLONE_UNAVAILABLE:
 531		kmem_cache_free(skbuff_head_cache, skb);
 532		break;
 533
 534	case SKB_FCLONE_ORIG:
 535		fclone_ref = (atomic_t *) (skb + 2);
 536		if (atomic_dec_and_test(fclone_ref))
 537			kmem_cache_free(skbuff_fclone_cache, skb);
 538		break;
 539
 540	case SKB_FCLONE_CLONE:
 541		fclone_ref = (atomic_t *) (skb + 1);
 542		other = skb - 1;
 543
 544		/* The clone portion is available for
 545		 * fast-cloning again.
 546		 */
 547		skb->fclone = SKB_FCLONE_UNAVAILABLE;
 548
 549		if (atomic_dec_and_test(fclone_ref))
 550			kmem_cache_free(skbuff_fclone_cache, other);
 551		break;
 552	}
 553}
 554
 555static void skb_release_head_state(struct sk_buff *skb)
 556{
 557	skb_dst_drop(skb);
 558#ifdef CONFIG_XFRM
 559	secpath_put(skb->sp);
 560#endif
 561	if (skb->destructor) {
 562		WARN_ON(in_irq());
 563		skb->destructor(skb);
 564	}
 565#if IS_ENABLED(CONFIG_NF_CONNTRACK)
 566	nf_conntrack_put(skb->nfct);
 567#endif
 
 
 
 568#ifdef CONFIG_BRIDGE_NETFILTER
 569	nf_bridge_put(skb->nf_bridge);
 570#endif
 571/* XXX: IS this still necessary? - JHS */
 572#ifdef CONFIG_NET_SCHED
 573	skb->tc_index = 0;
 574#ifdef CONFIG_NET_CLS_ACT
 575	skb->tc_verd = 0;
 576#endif
 577#endif
 578}
 579
 580/* Free everything but the sk_buff shell. */
 581static void skb_release_all(struct sk_buff *skb)
 582{
 583	skb_release_head_state(skb);
 584	if (likely(skb->head))
 585		skb_release_data(skb);
 586}
 587
 588/**
 589 *	__kfree_skb - private function
 590 *	@skb: buffer
 591 *
 592 *	Free an sk_buff. Release anything attached to the buffer.
 593 *	Clean the state. This is an internal helper function. Users should
 594 *	always call kfree_skb
 595 */
 596
 597void __kfree_skb(struct sk_buff *skb)
 598{
 599	skb_release_all(skb);
 600	kfree_skbmem(skb);
 601}
 602EXPORT_SYMBOL(__kfree_skb);
 603
 604/**
 605 *	kfree_skb - free an sk_buff
 606 *	@skb: buffer to free
 607 *
 608 *	Drop a reference to the buffer and free it if the usage count has
 609 *	hit zero.
 610 */
 611void kfree_skb(struct sk_buff *skb)
 612{
 613	if (unlikely(!skb))
 614		return;
 615	if (likely(atomic_read(&skb->users) == 1))
 616		smp_rmb();
 617	else if (likely(!atomic_dec_and_test(&skb->users)))
 618		return;
 619	trace_kfree_skb(skb, __builtin_return_address(0));
 620	__kfree_skb(skb);
 621}
 622EXPORT_SYMBOL(kfree_skb);
 623
 624void kfree_skb_list(struct sk_buff *segs)
 625{
 626	while (segs) {
 627		struct sk_buff *next = segs->next;
 628
 629		kfree_skb(segs);
 630		segs = next;
 631	}
 632}
 633EXPORT_SYMBOL(kfree_skb_list);
 634
 635/**
 636 *	skb_tx_error - report an sk_buff xmit error
 637 *	@skb: buffer that triggered an error
 638 *
 639 *	Report xmit error if a device callback is tracking this skb.
 640 *	skb must be freed afterwards.
 641 */
 642void skb_tx_error(struct sk_buff *skb)
 643{
 644	if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY) {
 645		struct ubuf_info *uarg;
 646
 647		uarg = skb_shinfo(skb)->destructor_arg;
 648		if (uarg->callback)
 649			uarg->callback(uarg, false);
 650		skb_shinfo(skb)->tx_flags &= ~SKBTX_DEV_ZEROCOPY;
 651	}
 652}
 653EXPORT_SYMBOL(skb_tx_error);
 654
 655/**
 656 *	consume_skb - free an skbuff
 657 *	@skb: buffer to free
 658 *
 659 *	Drop a ref to the buffer and free it if the usage count has hit zero
 660 *	Functions identically to kfree_skb, but kfree_skb assumes that the frame
 661 *	is being dropped after a failure and notes that
 662 */
 663void consume_skb(struct sk_buff *skb)
 664{
 665	if (unlikely(!skb))
 666		return;
 667	if (likely(atomic_read(&skb->users) == 1))
 668		smp_rmb();
 669	else if (likely(!atomic_dec_and_test(&skb->users)))
 670		return;
 671	trace_consume_skb(skb);
 672	__kfree_skb(skb);
 673}
 674EXPORT_SYMBOL(consume_skb);
 675
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 676static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
 677{
 678	new->tstamp		= old->tstamp;
 679	new->dev		= old->dev;
 680	new->transport_header	= old->transport_header;
 681	new->network_header	= old->network_header;
 682	new->mac_header		= old->mac_header;
 683	new->inner_protocol	= old->inner_protocol;
 684	new->inner_transport_header = old->inner_transport_header;
 685	new->inner_network_header = old->inner_network_header;
 686	new->inner_mac_header = old->inner_mac_header;
 687	skb_dst_copy(new, old);
 688	skb_copy_hash(new, old);
 689	new->ooo_okay		= old->ooo_okay;
 
 690	new->no_fcs		= old->no_fcs;
 691	new->encapsulation	= old->encapsulation;
 692#ifdef CONFIG_XFRM
 693	new->sp			= secpath_get(old->sp);
 694#endif
 695	memcpy(new->cb, old->cb, sizeof(old->cb));
 696	new->csum		= old->csum;
 697	new->local_df		= old->local_df;
 698	new->pkt_type		= old->pkt_type;
 699	new->ip_summed		= old->ip_summed;
 700	skb_copy_queue_mapping(new, old);
 701	new->priority		= old->priority;
 702#if IS_ENABLED(CONFIG_IP_VS)
 703	new->ipvs_property	= old->ipvs_property;
 704#endif
 705	new->pfmemalloc		= old->pfmemalloc;
 706	new->protocol		= old->protocol;
 707	new->mark		= old->mark;
 708	new->skb_iif		= old->skb_iif;
 709	__nf_copy(new, old);
 
 
 
 710#ifdef CONFIG_NET_SCHED
 711	new->tc_index		= old->tc_index;
 712#ifdef CONFIG_NET_CLS_ACT
 713	new->tc_verd		= old->tc_verd;
 714#endif
 715#endif
 716	new->vlan_proto		= old->vlan_proto;
 717	new->vlan_tci		= old->vlan_tci;
 718
 719	skb_copy_secmark(new, old);
 720
 721#ifdef CONFIG_NET_RX_BUSY_POLL
 722	new->napi_id	= old->napi_id;
 723#endif
 724}
 725
 726/*
 727 * You should not add any new code to this function.  Add it to
 728 * __copy_skb_header above instead.
 729 */
 730static struct sk_buff *__skb_clone(struct sk_buff *n, struct sk_buff *skb)
 731{
 732#define C(x) n->x = skb->x
 733
 734	n->next = n->prev = NULL;
 735	n->sk = NULL;
 736	__copy_skb_header(n, skb);
 737
 738	C(len);
 739	C(data_len);
 740	C(mac_len);
 741	n->hdr_len = skb->nohdr ? skb_headroom(skb) : skb->hdr_len;
 742	n->cloned = 1;
 743	n->nohdr = 0;
 744	n->destructor = NULL;
 745	C(tail);
 746	C(end);
 747	C(head);
 748	C(head_frag);
 749	C(data);
 750	C(truesize);
 751	atomic_set(&n->users, 1);
 752
 753	atomic_inc(&(skb_shinfo(skb)->dataref));
 754	skb->cloned = 1;
 755
 756	return n;
 757#undef C
 758}
 759
 760/**
 761 *	skb_morph	-	morph one skb into another
 762 *	@dst: the skb to receive the contents
 763 *	@src: the skb to supply the contents
 764 *
 765 *	This is identical to skb_clone except that the target skb is
 766 *	supplied by the user.
 767 *
 768 *	The target skb is returned upon exit.
 769 */
 770struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src)
 771{
 772	skb_release_all(dst);
 773	return __skb_clone(dst, src);
 774}
 775EXPORT_SYMBOL_GPL(skb_morph);
 776
 777/**
 778 *	skb_copy_ubufs	-	copy userspace skb frags buffers to kernel
 779 *	@skb: the skb to modify
 780 *	@gfp_mask: allocation priority
 781 *
 782 *	This must be called on SKBTX_DEV_ZEROCOPY skb.
 783 *	It will copy all frags into kernel and drop the reference
 784 *	to userspace pages.
 785 *
 786 *	If this function is called from an interrupt gfp_mask() must be
 787 *	%GFP_ATOMIC.
 788 *
 789 *	Returns 0 on success or a negative error code on failure
 790 *	to allocate kernel memory to copy to.
 791 */
 792int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask)
 793{
 794	int i;
 795	int num_frags = skb_shinfo(skb)->nr_frags;
 796	struct page *page, *head = NULL;
 797	struct ubuf_info *uarg = skb_shinfo(skb)->destructor_arg;
 798
 799	for (i = 0; i < num_frags; i++) {
 800		u8 *vaddr;
 801		skb_frag_t *f = &skb_shinfo(skb)->frags[i];
 802
 803		page = alloc_page(gfp_mask);
 804		if (!page) {
 805			while (head) {
 806				struct page *next = (struct page *)page_private(head);
 807				put_page(head);
 808				head = next;
 809			}
 810			return -ENOMEM;
 811		}
 812		vaddr = kmap_atomic(skb_frag_page(f));
 813		memcpy(page_address(page),
 814		       vaddr + f->page_offset, skb_frag_size(f));
 815		kunmap_atomic(vaddr);
 816		set_page_private(page, (unsigned long)head);
 817		head = page;
 818	}
 819
 820	/* skb frags release userspace buffers */
 821	for (i = 0; i < num_frags; i++)
 822		skb_frag_unref(skb, i);
 823
 824	uarg->callback(uarg, false);
 825
 826	/* skb frags point to kernel buffers */
 827	for (i = num_frags - 1; i >= 0; i--) {
 828		__skb_fill_page_desc(skb, i, head, 0,
 829				     skb_shinfo(skb)->frags[i].size);
 830		head = (struct page *)page_private(head);
 831	}
 832
 833	skb_shinfo(skb)->tx_flags &= ~SKBTX_DEV_ZEROCOPY;
 834	return 0;
 835}
 836EXPORT_SYMBOL_GPL(skb_copy_ubufs);
 837
 838/**
 839 *	skb_clone	-	duplicate an sk_buff
 840 *	@skb: buffer to clone
 841 *	@gfp_mask: allocation priority
 842 *
 843 *	Duplicate an &sk_buff. The new one is not owned by a socket. Both
 844 *	copies share the same packet data but not structure. The new
 845 *	buffer has a reference count of 1. If the allocation fails the
 846 *	function returns %NULL otherwise the new buffer is returned.
 847 *
 848 *	If this function is called from an interrupt gfp_mask() must be
 849 *	%GFP_ATOMIC.
 850 */
 851
 852struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
 853{
 854	struct sk_buff *n;
 855
 856	if (skb_orphan_frags(skb, gfp_mask))
 857		return NULL;
 
 
 858
 859	n = skb + 1;
 860	if (skb->fclone == SKB_FCLONE_ORIG &&
 861	    n->fclone == SKB_FCLONE_UNAVAILABLE) {
 862		atomic_t *fclone_ref = (atomic_t *) (n + 1);
 863		n->fclone = SKB_FCLONE_CLONE;
 864		atomic_inc(fclone_ref);
 865	} else {
 866		if (skb_pfmemalloc(skb))
 867			gfp_mask |= __GFP_MEMALLOC;
 868
 869		n = kmem_cache_alloc(skbuff_head_cache, gfp_mask);
 870		if (!n)
 871			return NULL;
 872
 873		kmemcheck_annotate_bitfield(n, flags1);
 874		kmemcheck_annotate_bitfield(n, flags2);
 875		n->fclone = SKB_FCLONE_UNAVAILABLE;
 876	}
 877
 878	return __skb_clone(n, skb);
 879}
 880EXPORT_SYMBOL(skb_clone);
 881
 882static void skb_headers_offset_update(struct sk_buff *skb, int off)
 883{
 884	/* Only adjust this if it actually is csum_start rather than csum */
 885	if (skb->ip_summed == CHECKSUM_PARTIAL)
 886		skb->csum_start += off;
 887	/* {transport,network,mac}_header and tail are relative to skb->head */
 888	skb->transport_header += off;
 889	skb->network_header   += off;
 890	if (skb_mac_header_was_set(skb))
 891		skb->mac_header += off;
 892	skb->inner_transport_header += off;
 893	skb->inner_network_header += off;
 894	skb->inner_mac_header += off;
 895}
 896
 897static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
 898{
 
 
 
 
 
 
 
 899	__copy_skb_header(new, old);
 900
 
 
 
 
 
 
 
 901	skb_shinfo(new)->gso_size = skb_shinfo(old)->gso_size;
 902	skb_shinfo(new)->gso_segs = skb_shinfo(old)->gso_segs;
 903	skb_shinfo(new)->gso_type = skb_shinfo(old)->gso_type;
 904}
 905
 906static inline int skb_alloc_rx_flag(const struct sk_buff *skb)
 907{
 908	if (skb_pfmemalloc(skb))
 909		return SKB_ALLOC_RX;
 910	return 0;
 911}
 912
 913/**
 914 *	skb_copy	-	create private copy of an sk_buff
 915 *	@skb: buffer to copy
 916 *	@gfp_mask: allocation priority
 917 *
 918 *	Make a copy of both an &sk_buff and its data. This is used when the
 919 *	caller wishes to modify the data and needs a private copy of the
 920 *	data to alter. Returns %NULL on failure or the pointer to the buffer
 921 *	on success. The returned buffer has a reference count of 1.
 922 *
 923 *	As by-product this function converts non-linear &sk_buff to linear
 924 *	one, so that &sk_buff becomes completely private and caller is allowed
 925 *	to modify all the data of returned buffer. This means that this
 926 *	function is not recommended for use in circumstances when only
 927 *	header is going to be modified. Use pskb_copy() instead.
 928 */
 929
 930struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t gfp_mask)
 931{
 932	int headerlen = skb_headroom(skb);
 933	unsigned int size = skb_end_offset(skb) + skb->data_len;
 934	struct sk_buff *n = __alloc_skb(size, gfp_mask,
 935					skb_alloc_rx_flag(skb), NUMA_NO_NODE);
 936
 937	if (!n)
 938		return NULL;
 939
 940	/* Set the data pointer */
 941	skb_reserve(n, headerlen);
 942	/* Set the tail pointer and length */
 943	skb_put(n, skb->len);
 944
 945	if (skb_copy_bits(skb, -headerlen, n->head, headerlen + skb->len))
 946		BUG();
 947
 948	copy_skb_header(n, skb);
 949	return n;
 950}
 951EXPORT_SYMBOL(skb_copy);
 952
 953/**
 954 *	__pskb_copy	-	create copy of an sk_buff with private head.
 955 *	@skb: buffer to copy
 956 *	@headroom: headroom of new skb
 957 *	@gfp_mask: allocation priority
 958 *
 959 *	Make a copy of both an &sk_buff and part of its data, located
 960 *	in header. Fragmented data remain shared. This is used when
 961 *	the caller wishes to modify only header of &sk_buff and needs
 962 *	private copy of the header to alter. Returns %NULL on failure
 963 *	or the pointer to the buffer on success.
 964 *	The returned buffer has a reference count of 1.
 965 */
 966
 967struct sk_buff *__pskb_copy(struct sk_buff *skb, int headroom, gfp_t gfp_mask)
 968{
 969	unsigned int size = skb_headlen(skb) + headroom;
 970	struct sk_buff *n = __alloc_skb(size, gfp_mask,
 971					skb_alloc_rx_flag(skb), NUMA_NO_NODE);
 972
 973	if (!n)
 974		goto out;
 975
 976	/* Set the data pointer */
 977	skb_reserve(n, headroom);
 978	/* Set the tail pointer and length */
 979	skb_put(n, skb_headlen(skb));
 980	/* Copy the bytes */
 981	skb_copy_from_linear_data(skb, n->data, n->len);
 982
 983	n->truesize += skb->data_len;
 984	n->data_len  = skb->data_len;
 985	n->len	     = skb->len;
 986
 987	if (skb_shinfo(skb)->nr_frags) {
 988		int i;
 989
 990		if (skb_orphan_frags(skb, gfp_mask)) {
 991			kfree_skb(n);
 992			n = NULL;
 993			goto out;
 
 
 994		}
 995		for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
 996			skb_shinfo(n)->frags[i] = skb_shinfo(skb)->frags[i];
 997			skb_frag_ref(skb, i);
 998		}
 999		skb_shinfo(n)->nr_frags = i;
1000	}
1001
1002	if (skb_has_frag_list(skb)) {
1003		skb_shinfo(n)->frag_list = skb_shinfo(skb)->frag_list;
1004		skb_clone_fraglist(n);
1005	}
1006
1007	copy_skb_header(n, skb);
1008out:
1009	return n;
1010}
1011EXPORT_SYMBOL(__pskb_copy);
1012
1013/**
1014 *	pskb_expand_head - reallocate header of &sk_buff
1015 *	@skb: buffer to reallocate
1016 *	@nhead: room to add at head
1017 *	@ntail: room to add at tail
1018 *	@gfp_mask: allocation priority
1019 *
1020 *	Expands (or creates identical copy, if @nhead and @ntail are zero)
1021 *	header of @skb. &sk_buff itself is not changed. &sk_buff MUST have
1022 *	reference count of 1. Returns zero in the case of success or error,
1023 *	if expansion failed. In the last case, &sk_buff is not changed.
1024 *
1025 *	All the pointers pointing into skb header may change and must be
1026 *	reloaded after call to this function.
1027 */
1028
1029int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
1030		     gfp_t gfp_mask)
1031{
1032	int i;
1033	u8 *data;
1034	int size = nhead + skb_end_offset(skb) + ntail;
1035	long off;
1036
1037	BUG_ON(nhead < 0);
1038
1039	if (skb_shared(skb))
1040		BUG();
1041
1042	size = SKB_DATA_ALIGN(size);
1043
1044	if (skb_pfmemalloc(skb))
1045		gfp_mask |= __GFP_MEMALLOC;
1046	data = kmalloc_reserve(size + SKB_DATA_ALIGN(sizeof(struct skb_shared_info)),
1047			       gfp_mask, NUMA_NO_NODE, NULL);
1048	if (!data)
1049		goto nodata;
1050	size = SKB_WITH_OVERHEAD(ksize(data));
1051
1052	/* Copy only real data... and, alas, header. This should be
1053	 * optimized for the cases when header is void.
1054	 */
1055	memcpy(data + nhead, skb->head, skb_tail_pointer(skb) - skb->head);
1056
1057	memcpy((struct skb_shared_info *)(data + size),
1058	       skb_shinfo(skb),
1059	       offsetof(struct skb_shared_info, frags[skb_shinfo(skb)->nr_frags]));
1060
1061	/*
1062	 * if shinfo is shared we must drop the old head gracefully, but if it
1063	 * is not we can just drop the old head and let the existing refcount
1064	 * be since all we did is relocate the values
1065	 */
1066	if (skb_cloned(skb)) {
1067		/* copy this zero copy skb frags */
1068		if (skb_orphan_frags(skb, gfp_mask))
1069			goto nofrags;
 
 
1070		for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
1071			skb_frag_ref(skb, i);
1072
1073		if (skb_has_frag_list(skb))
1074			skb_clone_fraglist(skb);
1075
1076		skb_release_data(skb);
1077	} else {
1078		skb_free_head(skb);
1079	}
1080	off = (data + nhead) - skb->head;
1081
1082	skb->head     = data;
1083	skb->head_frag = 0;
1084	skb->data    += off;
1085#ifdef NET_SKBUFF_DATA_USES_OFFSET
1086	skb->end      = size;
1087	off           = nhead;
1088#else
1089	skb->end      = skb->head + size;
1090#endif
 
1091	skb->tail	      += off;
1092	skb_headers_offset_update(skb, nhead);
 
 
 
 
 
 
1093	skb->cloned   = 0;
1094	skb->hdr_len  = 0;
1095	skb->nohdr    = 0;
1096	atomic_set(&skb_shinfo(skb)->dataref, 1);
1097	return 0;
1098
1099nofrags:
1100	kfree(data);
1101nodata:
1102	return -ENOMEM;
1103}
1104EXPORT_SYMBOL(pskb_expand_head);
1105
1106/* Make private copy of skb with writable head and some headroom */
1107
1108struct sk_buff *skb_realloc_headroom(struct sk_buff *skb, unsigned int headroom)
1109{
1110	struct sk_buff *skb2;
1111	int delta = headroom - skb_headroom(skb);
1112
1113	if (delta <= 0)
1114		skb2 = pskb_copy(skb, GFP_ATOMIC);
1115	else {
1116		skb2 = skb_clone(skb, GFP_ATOMIC);
1117		if (skb2 && pskb_expand_head(skb2, SKB_DATA_ALIGN(delta), 0,
1118					     GFP_ATOMIC)) {
1119			kfree_skb(skb2);
1120			skb2 = NULL;
1121		}
1122	}
1123	return skb2;
1124}
1125EXPORT_SYMBOL(skb_realloc_headroom);
1126
1127/**
1128 *	skb_copy_expand	-	copy and expand sk_buff
1129 *	@skb: buffer to copy
1130 *	@newheadroom: new free bytes at head
1131 *	@newtailroom: new free bytes at tail
1132 *	@gfp_mask: allocation priority
1133 *
1134 *	Make a copy of both an &sk_buff and its data and while doing so
1135 *	allocate additional space.
1136 *
1137 *	This is used when the caller wishes to modify the data and needs a
1138 *	private copy of the data to alter as well as more space for new fields.
1139 *	Returns %NULL on failure or the pointer to the buffer
1140 *	on success. The returned buffer has a reference count of 1.
1141 *
1142 *	You must pass %GFP_ATOMIC as the allocation priority if this function
1143 *	is called from an interrupt.
1144 */
1145struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
1146				int newheadroom, int newtailroom,
1147				gfp_t gfp_mask)
1148{
1149	/*
1150	 *	Allocate the copy buffer
1151	 */
1152	struct sk_buff *n = __alloc_skb(newheadroom + skb->len + newtailroom,
1153					gfp_mask, skb_alloc_rx_flag(skb),
1154					NUMA_NO_NODE);
1155	int oldheadroom = skb_headroom(skb);
1156	int head_copy_len, head_copy_off;
 
1157
1158	if (!n)
1159		return NULL;
1160
1161	skb_reserve(n, newheadroom);
1162
1163	/* Set the tail pointer and length */
1164	skb_put(n, skb->len);
1165
1166	head_copy_len = oldheadroom;
1167	head_copy_off = 0;
1168	if (newheadroom <= head_copy_len)
1169		head_copy_len = newheadroom;
1170	else
1171		head_copy_off = newheadroom - head_copy_len;
1172
1173	/* Copy the linear header and data. */
1174	if (skb_copy_bits(skb, -head_copy_len, n->head + head_copy_off,
1175			  skb->len + head_copy_len))
1176		BUG();
1177
1178	copy_skb_header(n, skb);
1179
1180	skb_headers_offset_update(n, newheadroom - oldheadroom);
 
 
 
 
 
 
 
 
1181
1182	return n;
1183}
1184EXPORT_SYMBOL(skb_copy_expand);
1185
1186/**
1187 *	skb_pad			-	zero pad the tail of an skb
1188 *	@skb: buffer to pad
1189 *	@pad: space to pad
1190 *
1191 *	Ensure that a buffer is followed by a padding area that is zero
1192 *	filled. Used by network drivers which may DMA or transfer data
1193 *	beyond the buffer end onto the wire.
1194 *
1195 *	May return error in out of memory cases. The skb is freed on error.
1196 */
1197
1198int skb_pad(struct sk_buff *skb, int pad)
1199{
1200	int err;
1201	int ntail;
1202
1203	/* If the skbuff is non linear tailroom is always zero.. */
1204	if (!skb_cloned(skb) && skb_tailroom(skb) >= pad) {
1205		memset(skb->data+skb->len, 0, pad);
1206		return 0;
1207	}
1208
1209	ntail = skb->data_len + pad - (skb->end - skb->tail);
1210	if (likely(skb_cloned(skb) || ntail > 0)) {
1211		err = pskb_expand_head(skb, 0, ntail, GFP_ATOMIC);
1212		if (unlikely(err))
1213			goto free_skb;
1214	}
1215
1216	/* FIXME: The use of this function with non-linear skb's really needs
1217	 * to be audited.
1218	 */
1219	err = skb_linearize(skb);
1220	if (unlikely(err))
1221		goto free_skb;
1222
1223	memset(skb->data + skb->len, 0, pad);
1224	return 0;
1225
1226free_skb:
1227	kfree_skb(skb);
1228	return err;
1229}
1230EXPORT_SYMBOL(skb_pad);
1231
1232/**
1233 *	pskb_put - add data to the tail of a potentially fragmented buffer
1234 *	@skb: start of the buffer to use
1235 *	@tail: tail fragment of the buffer to use
1236 *	@len: amount of data to add
1237 *
1238 *	This function extends the used data area of the potentially
1239 *	fragmented buffer. @tail must be the last fragment of @skb -- or
1240 *	@skb itself. If this would exceed the total buffer size the kernel
1241 *	will panic. A pointer to the first byte of the extra data is
1242 *	returned.
1243 */
1244
1245unsigned char *pskb_put(struct sk_buff *skb, struct sk_buff *tail, int len)
1246{
1247	if (tail != skb) {
1248		skb->data_len += len;
1249		skb->len += len;
1250	}
1251	return skb_put(tail, len);
1252}
1253EXPORT_SYMBOL_GPL(pskb_put);
1254
1255/**
1256 *	skb_put - add data to a buffer
1257 *	@skb: buffer to use
1258 *	@len: amount of data to add
1259 *
1260 *	This function extends the used data area of the buffer. If this would
1261 *	exceed the total buffer size the kernel will panic. A pointer to the
1262 *	first byte of the extra data is returned.
1263 */
1264unsigned char *skb_put(struct sk_buff *skb, unsigned int len)
1265{
1266	unsigned char *tmp = skb_tail_pointer(skb);
1267	SKB_LINEAR_ASSERT(skb);
1268	skb->tail += len;
1269	skb->len  += len;
1270	if (unlikely(skb->tail > skb->end))
1271		skb_over_panic(skb, len, __builtin_return_address(0));
1272	return tmp;
1273}
1274EXPORT_SYMBOL(skb_put);
1275
1276/**
1277 *	skb_push - add data to the start of a buffer
1278 *	@skb: buffer to use
1279 *	@len: amount of data to add
1280 *
1281 *	This function extends the used data area of the buffer at the buffer
1282 *	start. If this would exceed the total buffer headroom the kernel will
1283 *	panic. A pointer to the first byte of the extra data is returned.
1284 */
1285unsigned char *skb_push(struct sk_buff *skb, unsigned int len)
1286{
1287	skb->data -= len;
1288	skb->len  += len;
1289	if (unlikely(skb->data<skb->head))
1290		skb_under_panic(skb, len, __builtin_return_address(0));
1291	return skb->data;
1292}
1293EXPORT_SYMBOL(skb_push);
1294
1295/**
1296 *	skb_pull - remove data from the start of a buffer
1297 *	@skb: buffer to use
1298 *	@len: amount of data to remove
1299 *
1300 *	This function removes data from the start of a buffer, returning
1301 *	the memory to the headroom. A pointer to the next data in the buffer
1302 *	is returned. Once the data has been pulled future pushes will overwrite
1303 *	the old data.
1304 */
1305unsigned char *skb_pull(struct sk_buff *skb, unsigned int len)
1306{
1307	return skb_pull_inline(skb, len);
1308}
1309EXPORT_SYMBOL(skb_pull);
1310
1311/**
1312 *	skb_trim - remove end from a buffer
1313 *	@skb: buffer to alter
1314 *	@len: new length
1315 *
1316 *	Cut the length of a buffer down by removing data from the tail. If
1317 *	the buffer is already under the length specified it is not modified.
1318 *	The skb must be linear.
1319 */
1320void skb_trim(struct sk_buff *skb, unsigned int len)
1321{
1322	if (skb->len > len)
1323		__skb_trim(skb, len);
1324}
1325EXPORT_SYMBOL(skb_trim);
1326
1327/* Trims skb to length len. It can change skb pointers.
1328 */
1329
1330int ___pskb_trim(struct sk_buff *skb, unsigned int len)
1331{
1332	struct sk_buff **fragp;
1333	struct sk_buff *frag;
1334	int offset = skb_headlen(skb);
1335	int nfrags = skb_shinfo(skb)->nr_frags;
1336	int i;
1337	int err;
1338
1339	if (skb_cloned(skb) &&
1340	    unlikely((err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC))))
1341		return err;
1342
1343	i = 0;
1344	if (offset >= len)
1345		goto drop_pages;
1346
1347	for (; i < nfrags; i++) {
1348		int end = offset + skb_frag_size(&skb_shinfo(skb)->frags[i]);
1349
1350		if (end < len) {
1351			offset = end;
1352			continue;
1353		}
1354
1355		skb_frag_size_set(&skb_shinfo(skb)->frags[i++], len - offset);
1356
1357drop_pages:
1358		skb_shinfo(skb)->nr_frags = i;
1359
1360		for (; i < nfrags; i++)
1361			skb_frag_unref(skb, i);
1362
1363		if (skb_has_frag_list(skb))
1364			skb_drop_fraglist(skb);
1365		goto done;
1366	}
1367
1368	for (fragp = &skb_shinfo(skb)->frag_list; (frag = *fragp);
1369	     fragp = &frag->next) {
1370		int end = offset + frag->len;
1371
1372		if (skb_shared(frag)) {
1373			struct sk_buff *nfrag;
1374
1375			nfrag = skb_clone(frag, GFP_ATOMIC);
1376			if (unlikely(!nfrag))
1377				return -ENOMEM;
1378
1379			nfrag->next = frag->next;
1380			consume_skb(frag);
1381			frag = nfrag;
1382			*fragp = frag;
1383		}
1384
1385		if (end < len) {
1386			offset = end;
1387			continue;
1388		}
1389
1390		if (end > len &&
1391		    unlikely((err = pskb_trim(frag, len - offset))))
1392			return err;
1393
1394		if (frag->next)
1395			skb_drop_list(&frag->next);
1396		break;
1397	}
1398
1399done:
1400	if (len > skb_headlen(skb)) {
1401		skb->data_len -= skb->len - len;
1402		skb->len       = len;
1403	} else {
1404		skb->len       = len;
1405		skb->data_len  = 0;
1406		skb_set_tail_pointer(skb, len);
1407	}
1408
1409	return 0;
1410}
1411EXPORT_SYMBOL(___pskb_trim);
1412
1413/**
1414 *	__pskb_pull_tail - advance tail of skb header
1415 *	@skb: buffer to reallocate
1416 *	@delta: number of bytes to advance tail
1417 *
1418 *	The function makes a sense only on a fragmented &sk_buff,
1419 *	it expands header moving its tail forward and copying necessary
1420 *	data from fragmented part.
1421 *
1422 *	&sk_buff MUST have reference count of 1.
1423 *
1424 *	Returns %NULL (and &sk_buff does not change) if pull failed
1425 *	or value of new tail of skb in the case of success.
1426 *
1427 *	All the pointers pointing into skb header may change and must be
1428 *	reloaded after call to this function.
1429 */
1430
1431/* Moves tail of skb head forward, copying data from fragmented part,
1432 * when it is necessary.
1433 * 1. It may fail due to malloc failure.
1434 * 2. It may change skb pointers.
1435 *
1436 * It is pretty complicated. Luckily, it is called only in exceptional cases.
1437 */
1438unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta)
1439{
1440	/* If skb has not enough free space at tail, get new one
1441	 * plus 128 bytes for future expansions. If we have enough
1442	 * room at tail, reallocate without expansion only if skb is cloned.
1443	 */
1444	int i, k, eat = (skb->tail + delta) - skb->end;
1445
1446	if (eat > 0 || skb_cloned(skb)) {
1447		if (pskb_expand_head(skb, 0, eat > 0 ? eat + 128 : 0,
1448				     GFP_ATOMIC))
1449			return NULL;
1450	}
1451
1452	if (skb_copy_bits(skb, skb_headlen(skb), skb_tail_pointer(skb), delta))
1453		BUG();
1454
1455	/* Optimization: no fragments, no reasons to preestimate
1456	 * size of pulled pages. Superb.
1457	 */
1458	if (!skb_has_frag_list(skb))
1459		goto pull_pages;
1460
1461	/* Estimate size of pulled pages. */
1462	eat = delta;
1463	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1464		int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
1465
1466		if (size >= eat)
1467			goto pull_pages;
1468		eat -= size;
1469	}
1470
1471	/* If we need update frag list, we are in troubles.
1472	 * Certainly, it possible to add an offset to skb data,
1473	 * but taking into account that pulling is expected to
1474	 * be very rare operation, it is worth to fight against
1475	 * further bloating skb head and crucify ourselves here instead.
1476	 * Pure masohism, indeed. 8)8)
1477	 */
1478	if (eat) {
1479		struct sk_buff *list = skb_shinfo(skb)->frag_list;
1480		struct sk_buff *clone = NULL;
1481		struct sk_buff *insp = NULL;
1482
1483		do {
1484			BUG_ON(!list);
1485
1486			if (list->len <= eat) {
1487				/* Eaten as whole. */
1488				eat -= list->len;
1489				list = list->next;
1490				insp = list;
1491			} else {
1492				/* Eaten partially. */
1493
1494				if (skb_shared(list)) {
1495					/* Sucks! We need to fork list. :-( */
1496					clone = skb_clone(list, GFP_ATOMIC);
1497					if (!clone)
1498						return NULL;
1499					insp = list->next;
1500					list = clone;
1501				} else {
1502					/* This may be pulled without
1503					 * problems. */
1504					insp = list;
1505				}
1506				if (!pskb_pull(list, eat)) {
1507					kfree_skb(clone);
1508					return NULL;
1509				}
1510				break;
1511			}
1512		} while (eat);
1513
1514		/* Free pulled out fragments. */
1515		while ((list = skb_shinfo(skb)->frag_list) != insp) {
1516			skb_shinfo(skb)->frag_list = list->next;
1517			kfree_skb(list);
1518		}
1519		/* And insert new clone at head. */
1520		if (clone) {
1521			clone->next = list;
1522			skb_shinfo(skb)->frag_list = clone;
1523		}
1524	}
1525	/* Success! Now we may commit changes to skb data. */
1526
1527pull_pages:
1528	eat = delta;
1529	k = 0;
1530	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1531		int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
1532
1533		if (size <= eat) {
1534			skb_frag_unref(skb, i);
1535			eat -= size;
1536		} else {
1537			skb_shinfo(skb)->frags[k] = skb_shinfo(skb)->frags[i];
1538			if (eat) {
1539				skb_shinfo(skb)->frags[k].page_offset += eat;
1540				skb_frag_size_sub(&skb_shinfo(skb)->frags[k], eat);
1541				eat = 0;
1542			}
1543			k++;
1544		}
1545	}
1546	skb_shinfo(skb)->nr_frags = k;
1547
1548	skb->tail     += delta;
1549	skb->data_len -= delta;
1550
1551	return skb_tail_pointer(skb);
1552}
1553EXPORT_SYMBOL(__pskb_pull_tail);
1554
1555/**
1556 *	skb_copy_bits - copy bits from skb to kernel buffer
1557 *	@skb: source skb
1558 *	@offset: offset in source
1559 *	@to: destination buffer
1560 *	@len: number of bytes to copy
1561 *
1562 *	Copy the specified number of bytes from the source skb to the
1563 *	destination buffer.
1564 *
1565 *	CAUTION ! :
1566 *		If its prototype is ever changed,
1567 *		check arch/{*}/net/{*}.S files,
1568 *		since it is called from BPF assembly code.
1569 */
1570int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len)
1571{
1572	int start = skb_headlen(skb);
1573	struct sk_buff *frag_iter;
1574	int i, copy;
1575
1576	if (offset > (int)skb->len - len)
1577		goto fault;
1578
1579	/* Copy header. */
1580	if ((copy = start - offset) > 0) {
1581		if (copy > len)
1582			copy = len;
1583		skb_copy_from_linear_data_offset(skb, offset, to, copy);
1584		if ((len -= copy) == 0)
1585			return 0;
1586		offset += copy;
1587		to     += copy;
1588	}
1589
1590	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1591		int end;
1592		skb_frag_t *f = &skb_shinfo(skb)->frags[i];
1593
1594		WARN_ON(start > offset + len);
1595
1596		end = start + skb_frag_size(f);
1597		if ((copy = end - offset) > 0) {
1598			u8 *vaddr;
1599
1600			if (copy > len)
1601				copy = len;
1602
1603			vaddr = kmap_atomic(skb_frag_page(f));
1604			memcpy(to,
1605			       vaddr + f->page_offset + offset - start,
1606			       copy);
1607			kunmap_atomic(vaddr);
1608
1609			if ((len -= copy) == 0)
1610				return 0;
1611			offset += copy;
1612			to     += copy;
1613		}
1614		start = end;
1615	}
1616
1617	skb_walk_frags(skb, frag_iter) {
1618		int end;
1619
1620		WARN_ON(start > offset + len);
1621
1622		end = start + frag_iter->len;
1623		if ((copy = end - offset) > 0) {
1624			if (copy > len)
1625				copy = len;
1626			if (skb_copy_bits(frag_iter, offset - start, to, copy))
1627				goto fault;
1628			if ((len -= copy) == 0)
1629				return 0;
1630			offset += copy;
1631			to     += copy;
1632		}
1633		start = end;
1634	}
1635
1636	if (!len)
1637		return 0;
1638
1639fault:
1640	return -EFAULT;
1641}
1642EXPORT_SYMBOL(skb_copy_bits);
1643
1644/*
1645 * Callback from splice_to_pipe(), if we need to release some pages
1646 * at the end of the spd in case we error'ed out in filling the pipe.
1647 */
1648static void sock_spd_release(struct splice_pipe_desc *spd, unsigned int i)
1649{
1650	put_page(spd->pages[i]);
1651}
1652
1653static struct page *linear_to_page(struct page *page, unsigned int *len,
1654				   unsigned int *offset,
1655				   struct sock *sk)
1656{
1657	struct page_frag *pfrag = sk_page_frag(sk);
 
1658
1659	if (!sk_page_frag_refill(sk, pfrag))
1660		return NULL;
 
 
 
1661
1662	*len = min_t(unsigned int, *len, pfrag->size - pfrag->offset);
 
 
 
1663
1664	memcpy(page_address(pfrag->page) + pfrag->offset,
1665	       page_address(page) + *offset, *len);
1666	*offset = pfrag->offset;
1667	pfrag->offset += *len;
 
 
 
 
 
1668
1669	return pfrag->page;
 
 
 
 
 
 
 
1670}
1671
1672static bool spd_can_coalesce(const struct splice_pipe_desc *spd,
1673			     struct page *page,
1674			     unsigned int offset)
1675{
1676	return	spd->nr_pages &&
1677		spd->pages[spd->nr_pages - 1] == page &&
1678		(spd->partial[spd->nr_pages - 1].offset +
1679		 spd->partial[spd->nr_pages - 1].len == offset);
1680}
1681
1682/*
1683 * Fill page/offset/length into spd, if it can hold more pages.
1684 */
1685static bool spd_fill_page(struct splice_pipe_desc *spd,
1686			  struct pipe_inode_info *pipe, struct page *page,
1687			  unsigned int *len, unsigned int offset,
1688			  bool linear,
1689			  struct sock *sk)
1690{
1691	if (unlikely(spd->nr_pages == MAX_SKB_FRAGS))
1692		return true;
1693
1694	if (linear) {
1695		page = linear_to_page(page, len, &offset, sk);
1696		if (!page)
1697			return true;
1698	}
1699	if (spd_can_coalesce(spd, page, offset)) {
1700		spd->partial[spd->nr_pages - 1].len += *len;
1701		return false;
1702	}
1703	get_page(page);
1704	spd->pages[spd->nr_pages] = page;
1705	spd->partial[spd->nr_pages].len = *len;
1706	spd->partial[spd->nr_pages].offset = offset;
1707	spd->nr_pages++;
1708
1709	return false;
1710}
1711
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1712static bool __splice_segment(struct page *page, unsigned int poff,
1713			     unsigned int plen, unsigned int *off,
1714			     unsigned int *len,
1715			     struct splice_pipe_desc *spd, bool linear,
1716			     struct sock *sk,
1717			     struct pipe_inode_info *pipe)
1718{
1719	if (!*len)
1720		return true;
1721
1722	/* skip this segment if already processed */
1723	if (*off >= plen) {
1724		*off -= plen;
1725		return false;
1726	}
1727
1728	/* ignore any bits we already processed */
1729	poff += *off;
1730	plen -= *off;
1731	*off = 0;
 
1732
1733	do {
1734		unsigned int flen = min(*len, plen);
1735
1736		if (spd_fill_page(spd, pipe, page, &flen, poff,
1737				  linear, sk))
 
 
1738			return true;
1739		poff += flen;
1740		plen -= flen;
1741		*len -= flen;
 
1742	} while (*len && plen);
1743
1744	return false;
1745}
1746
1747/*
1748 * Map linear and fragment data from the skb to spd. It reports true if the
1749 * pipe is full or if we already spliced the requested length.
1750 */
1751static bool __skb_splice_bits(struct sk_buff *skb, struct pipe_inode_info *pipe,
1752			      unsigned int *offset, unsigned int *len,
1753			      struct splice_pipe_desc *spd, struct sock *sk)
1754{
1755	int seg;
1756
1757	/* map the linear part :
1758	 * If skb->head_frag is set, this 'linear' part is backed by a
1759	 * fragment, and if the head is not shared with any clones then
1760	 * we can avoid a copy since we own the head portion of this page.
1761	 */
1762	if (__splice_segment(virt_to_page(skb->data),
1763			     (unsigned long) skb->data & (PAGE_SIZE - 1),
1764			     skb_headlen(skb),
1765			     offset, len, spd,
1766			     skb_head_is_locked(skb),
1767			     sk, pipe))
1768		return true;
1769
1770	/*
1771	 * then map the fragments
1772	 */
1773	for (seg = 0; seg < skb_shinfo(skb)->nr_frags; seg++) {
1774		const skb_frag_t *f = &skb_shinfo(skb)->frags[seg];
1775
1776		if (__splice_segment(skb_frag_page(f),
1777				     f->page_offset, skb_frag_size(f),
1778				     offset, len, spd, false, sk, pipe))
1779			return true;
1780	}
1781
1782	return false;
1783}
1784
1785/*
1786 * Map data from the skb to a pipe. Should handle both the linear part,
1787 * the fragments, and the frag list. It does NOT handle frag lists within
1788 * the frag list, if such a thing exists. We'd probably need to recurse to
1789 * handle that cleanly.
1790 */
1791int skb_splice_bits(struct sk_buff *skb, unsigned int offset,
1792		    struct pipe_inode_info *pipe, unsigned int tlen,
1793		    unsigned int flags)
1794{
1795	struct partial_page partial[MAX_SKB_FRAGS];
1796	struct page *pages[MAX_SKB_FRAGS];
1797	struct splice_pipe_desc spd = {
1798		.pages = pages,
1799		.partial = partial,
1800		.nr_pages_max = MAX_SKB_FRAGS,
1801		.flags = flags,
1802		.ops = &nosteal_pipe_buf_ops,
1803		.spd_release = sock_spd_release,
1804	};
1805	struct sk_buff *frag_iter;
1806	struct sock *sk = skb->sk;
1807	int ret = 0;
1808
1809	/*
1810	 * __skb_splice_bits() only fails if the output has no room left,
1811	 * so no point in going over the frag_list for the error case.
1812	 */
1813	if (__skb_splice_bits(skb, pipe, &offset, &tlen, &spd, sk))
1814		goto done;
1815	else if (!tlen)
1816		goto done;
1817
1818	/*
1819	 * now see if we have a frag_list to map
1820	 */
1821	skb_walk_frags(skb, frag_iter) {
1822		if (!tlen)
1823			break;
1824		if (__skb_splice_bits(frag_iter, pipe, &offset, &tlen, &spd, sk))
1825			break;
1826	}
1827
1828done:
1829	if (spd.nr_pages) {
1830		/*
1831		 * Drop the socket lock, otherwise we have reverse
1832		 * locking dependencies between sk_lock and i_mutex
1833		 * here as compared to sendfile(). We enter here
1834		 * with the socket lock held, and splice_to_pipe() will
1835		 * grab the pipe inode lock. For sendfile() emulation,
1836		 * we call into ->sendpage() with the i_mutex lock held
1837		 * and networking will grab the socket lock.
1838		 */
1839		release_sock(sk);
1840		ret = splice_to_pipe(pipe, &spd);
1841		lock_sock(sk);
1842	}
1843
1844	return ret;
1845}
1846
1847/**
1848 *	skb_store_bits - store bits from kernel buffer to skb
1849 *	@skb: destination buffer
1850 *	@offset: offset in destination
1851 *	@from: source buffer
1852 *	@len: number of bytes to copy
1853 *
1854 *	Copy the specified number of bytes from the source buffer to the
1855 *	destination skb.  This function handles all the messy bits of
1856 *	traversing fragment lists and such.
1857 */
1858
1859int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len)
1860{
1861	int start = skb_headlen(skb);
1862	struct sk_buff *frag_iter;
1863	int i, copy;
1864
1865	if (offset > (int)skb->len - len)
1866		goto fault;
1867
1868	if ((copy = start - offset) > 0) {
1869		if (copy > len)
1870			copy = len;
1871		skb_copy_to_linear_data_offset(skb, offset, from, copy);
1872		if ((len -= copy) == 0)
1873			return 0;
1874		offset += copy;
1875		from += copy;
1876	}
1877
1878	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1879		skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1880		int end;
1881
1882		WARN_ON(start > offset + len);
1883
1884		end = start + skb_frag_size(frag);
1885		if ((copy = end - offset) > 0) {
1886			u8 *vaddr;
1887
1888			if (copy > len)
1889				copy = len;
1890
1891			vaddr = kmap_atomic(skb_frag_page(frag));
1892			memcpy(vaddr + frag->page_offset + offset - start,
1893			       from, copy);
1894			kunmap_atomic(vaddr);
1895
1896			if ((len -= copy) == 0)
1897				return 0;
1898			offset += copy;
1899			from += copy;
1900		}
1901		start = end;
1902	}
1903
1904	skb_walk_frags(skb, frag_iter) {
1905		int end;
1906
1907		WARN_ON(start > offset + len);
1908
1909		end = start + frag_iter->len;
1910		if ((copy = end - offset) > 0) {
1911			if (copy > len)
1912				copy = len;
1913			if (skb_store_bits(frag_iter, offset - start,
1914					   from, copy))
1915				goto fault;
1916			if ((len -= copy) == 0)
1917				return 0;
1918			offset += copy;
1919			from += copy;
1920		}
1921		start = end;
1922	}
1923	if (!len)
1924		return 0;
1925
1926fault:
1927	return -EFAULT;
1928}
1929EXPORT_SYMBOL(skb_store_bits);
1930
1931/* Checksum skb data. */
1932__wsum __skb_checksum(const struct sk_buff *skb, int offset, int len,
1933		      __wsum csum, const struct skb_checksum_ops *ops)
 
1934{
1935	int start = skb_headlen(skb);
1936	int i, copy = start - offset;
1937	struct sk_buff *frag_iter;
1938	int pos = 0;
1939
1940	/* Checksum header. */
1941	if (copy > 0) {
1942		if (copy > len)
1943			copy = len;
1944		csum = ops->update(skb->data + offset, copy, csum);
1945		if ((len -= copy) == 0)
1946			return csum;
1947		offset += copy;
1948		pos	= copy;
1949	}
1950
1951	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
1952		int end;
1953		skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1954
1955		WARN_ON(start > offset + len);
1956
1957		end = start + skb_frag_size(frag);
1958		if ((copy = end - offset) > 0) {
1959			__wsum csum2;
1960			u8 *vaddr;
1961
1962			if (copy > len)
1963				copy = len;
1964			vaddr = kmap_atomic(skb_frag_page(frag));
1965			csum2 = ops->update(vaddr + frag->page_offset +
1966					    offset - start, copy, 0);
1967			kunmap_atomic(vaddr);
1968			csum = ops->combine(csum, csum2, pos, copy);
1969			if (!(len -= copy))
1970				return csum;
1971			offset += copy;
1972			pos    += copy;
1973		}
1974		start = end;
1975	}
1976
1977	skb_walk_frags(skb, frag_iter) {
1978		int end;
1979
1980		WARN_ON(start > offset + len);
1981
1982		end = start + frag_iter->len;
1983		if ((copy = end - offset) > 0) {
1984			__wsum csum2;
1985			if (copy > len)
1986				copy = len;
1987			csum2 = __skb_checksum(frag_iter, offset - start,
1988					       copy, 0, ops);
1989			csum = ops->combine(csum, csum2, pos, copy);
1990			if ((len -= copy) == 0)
1991				return csum;
1992			offset += copy;
1993			pos    += copy;
1994		}
1995		start = end;
1996	}
1997	BUG_ON(len);
1998
1999	return csum;
2000}
2001EXPORT_SYMBOL(__skb_checksum);
2002
2003__wsum skb_checksum(const struct sk_buff *skb, int offset,
2004		    int len, __wsum csum)
2005{
2006	const struct skb_checksum_ops ops = {
2007		.update  = csum_partial_ext,
2008		.combine = csum_block_add_ext,
2009	};
2010
2011	return __skb_checksum(skb, offset, len, csum, &ops);
2012}
2013EXPORT_SYMBOL(skb_checksum);
2014
2015/* Both of above in one bottle. */
2016
2017__wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset,
2018				    u8 *to, int len, __wsum csum)
2019{
2020	int start = skb_headlen(skb);
2021	int i, copy = start - offset;
2022	struct sk_buff *frag_iter;
2023	int pos = 0;
2024
2025	/* Copy header. */
2026	if (copy > 0) {
2027		if (copy > len)
2028			copy = len;
2029		csum = csum_partial_copy_nocheck(skb->data + offset, to,
2030						 copy, csum);
2031		if ((len -= copy) == 0)
2032			return csum;
2033		offset += copy;
2034		to     += copy;
2035		pos	= copy;
2036	}
2037
2038	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
2039		int end;
2040
2041		WARN_ON(start > offset + len);
2042
2043		end = start + skb_frag_size(&skb_shinfo(skb)->frags[i]);
2044		if ((copy = end - offset) > 0) {
2045			__wsum csum2;
2046			u8 *vaddr;
2047			skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
2048
2049			if (copy > len)
2050				copy = len;
2051			vaddr = kmap_atomic(skb_frag_page(frag));
2052			csum2 = csum_partial_copy_nocheck(vaddr +
2053							  frag->page_offset +
2054							  offset - start, to,
2055							  copy, 0);
2056			kunmap_atomic(vaddr);
2057			csum = csum_block_add(csum, csum2, pos);
2058			if (!(len -= copy))
2059				return csum;
2060			offset += copy;
2061			to     += copy;
2062			pos    += copy;
2063		}
2064		start = end;
2065	}
2066
2067	skb_walk_frags(skb, frag_iter) {
2068		__wsum csum2;
2069		int end;
2070
2071		WARN_ON(start > offset + len);
2072
2073		end = start + frag_iter->len;
2074		if ((copy = end - offset) > 0) {
2075			if (copy > len)
2076				copy = len;
2077			csum2 = skb_copy_and_csum_bits(frag_iter,
2078						       offset - start,
2079						       to, copy, 0);
2080			csum = csum_block_add(csum, csum2, pos);
2081			if ((len -= copy) == 0)
2082				return csum;
2083			offset += copy;
2084			to     += copy;
2085			pos    += copy;
2086		}
2087		start = end;
2088	}
2089	BUG_ON(len);
2090	return csum;
2091}
2092EXPORT_SYMBOL(skb_copy_and_csum_bits);
2093
2094 /**
2095 *	skb_zerocopy_headlen - Calculate headroom needed for skb_zerocopy()
2096 *	@from: source buffer
2097 *
2098 *	Calculates the amount of linear headroom needed in the 'to' skb passed
2099 *	into skb_zerocopy().
2100 */
2101unsigned int
2102skb_zerocopy_headlen(const struct sk_buff *from)
2103{
2104	unsigned int hlen = 0;
2105
2106	if (!from->head_frag ||
2107	    skb_headlen(from) < L1_CACHE_BYTES ||
2108	    skb_shinfo(from)->nr_frags >= MAX_SKB_FRAGS)
2109		hlen = skb_headlen(from);
2110
2111	if (skb_has_frag_list(from))
2112		hlen = from->len;
2113
2114	return hlen;
2115}
2116EXPORT_SYMBOL_GPL(skb_zerocopy_headlen);
2117
2118/**
2119 *	skb_zerocopy - Zero copy skb to skb
2120 *	@to: destination buffer
2121 *	@from: source buffer
2122 *	@len: number of bytes to copy from source buffer
2123 *	@hlen: size of linear headroom in destination buffer
2124 *
2125 *	Copies up to `len` bytes from `from` to `to` by creating references
2126 *	to the frags in the source buffer.
2127 *
2128 *	The `hlen` as calculated by skb_zerocopy_headlen() specifies the
2129 *	headroom in the `to` buffer.
2130 *
2131 *	Return value:
2132 *	0: everything is OK
2133 *	-ENOMEM: couldn't orphan frags of @from due to lack of memory
2134 *	-EFAULT: skb_copy_bits() found some problem with skb geometry
2135 */
2136int
2137skb_zerocopy(struct sk_buff *to, struct sk_buff *from, int len, int hlen)
2138{
2139	int i, j = 0;
2140	int plen = 0; /* length of skb->head fragment */
2141	int ret;
2142	struct page *page;
2143	unsigned int offset;
2144
2145	BUG_ON(!from->head_frag && !hlen);
2146
2147	/* dont bother with small payloads */
2148	if (len <= skb_tailroom(to))
2149		return skb_copy_bits(from, 0, skb_put(to, len), len);
2150
2151	if (hlen) {
2152		ret = skb_copy_bits(from, 0, skb_put(to, hlen), hlen);
2153		if (unlikely(ret))
2154			return ret;
2155		len -= hlen;
2156	} else {
2157		plen = min_t(int, skb_headlen(from), len);
2158		if (plen) {
2159			page = virt_to_head_page(from->head);
2160			offset = from->data - (unsigned char *)page_address(page);
2161			__skb_fill_page_desc(to, 0, page, offset, plen);
2162			get_page(page);
2163			j = 1;
2164			len -= plen;
2165		}
2166	}
2167
2168	to->truesize += len + plen;
2169	to->len += len + plen;
2170	to->data_len += len + plen;
2171
2172	if (unlikely(skb_orphan_frags(from, GFP_ATOMIC))) {
2173		skb_tx_error(from);
2174		return -ENOMEM;
2175	}
2176
2177	for (i = 0; i < skb_shinfo(from)->nr_frags; i++) {
2178		if (!len)
2179			break;
2180		skb_shinfo(to)->frags[j] = skb_shinfo(from)->frags[i];
2181		skb_shinfo(to)->frags[j].size = min_t(int, skb_shinfo(to)->frags[j].size, len);
2182		len -= skb_shinfo(to)->frags[j].size;
2183		skb_frag_ref(to, j);
2184		j++;
2185	}
2186	skb_shinfo(to)->nr_frags = j;
2187
2188	return 0;
2189}
2190EXPORT_SYMBOL_GPL(skb_zerocopy);
2191
2192void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to)
2193{
2194	__wsum csum;
2195	long csstart;
2196
2197	if (skb->ip_summed == CHECKSUM_PARTIAL)
2198		csstart = skb_checksum_start_offset(skb);
2199	else
2200		csstart = skb_headlen(skb);
2201
2202	BUG_ON(csstart > skb_headlen(skb));
2203
2204	skb_copy_from_linear_data(skb, to, csstart);
2205
2206	csum = 0;
2207	if (csstart != skb->len)
2208		csum = skb_copy_and_csum_bits(skb, csstart, to + csstart,
2209					      skb->len - csstart, 0);
2210
2211	if (skb->ip_summed == CHECKSUM_PARTIAL) {
2212		long csstuff = csstart + skb->csum_offset;
2213
2214		*((__sum16 *)(to + csstuff)) = csum_fold(csum);
2215	}
2216}
2217EXPORT_SYMBOL(skb_copy_and_csum_dev);
2218
2219/**
2220 *	skb_dequeue - remove from the head of the queue
2221 *	@list: list to dequeue from
2222 *
2223 *	Remove the head of the list. The list lock is taken so the function
2224 *	may be used safely with other locking list functions. The head item is
2225 *	returned or %NULL if the list is empty.
2226 */
2227
2228struct sk_buff *skb_dequeue(struct sk_buff_head *list)
2229{
2230	unsigned long flags;
2231	struct sk_buff *result;
2232
2233	spin_lock_irqsave(&list->lock, flags);
2234	result = __skb_dequeue(list);
2235	spin_unlock_irqrestore(&list->lock, flags);
2236	return result;
2237}
2238EXPORT_SYMBOL(skb_dequeue);
2239
2240/**
2241 *	skb_dequeue_tail - remove from the tail of the queue
2242 *	@list: list to dequeue from
2243 *
2244 *	Remove the tail of the list. The list lock is taken so the function
2245 *	may be used safely with other locking list functions. The tail item is
2246 *	returned or %NULL if the list is empty.
2247 */
2248struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list)
2249{
2250	unsigned long flags;
2251	struct sk_buff *result;
2252
2253	spin_lock_irqsave(&list->lock, flags);
2254	result = __skb_dequeue_tail(list);
2255	spin_unlock_irqrestore(&list->lock, flags);
2256	return result;
2257}
2258EXPORT_SYMBOL(skb_dequeue_tail);
2259
2260/**
2261 *	skb_queue_purge - empty a list
2262 *	@list: list to empty
2263 *
2264 *	Delete all buffers on an &sk_buff list. Each buffer is removed from
2265 *	the list and one reference dropped. This function takes the list
2266 *	lock and is atomic with respect to other list locking functions.
2267 */
2268void skb_queue_purge(struct sk_buff_head *list)
2269{
2270	struct sk_buff *skb;
2271	while ((skb = skb_dequeue(list)) != NULL)
2272		kfree_skb(skb);
2273}
2274EXPORT_SYMBOL(skb_queue_purge);
2275
2276/**
2277 *	skb_queue_head - queue a buffer at the list head
2278 *	@list: list to use
2279 *	@newsk: buffer to queue
2280 *
2281 *	Queue a buffer at the start of the list. This function takes the
2282 *	list lock and can be used safely with other locking &sk_buff functions
2283 *	safely.
2284 *
2285 *	A buffer cannot be placed on two lists at the same time.
2286 */
2287void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk)
2288{
2289	unsigned long flags;
2290
2291	spin_lock_irqsave(&list->lock, flags);
2292	__skb_queue_head(list, newsk);
2293	spin_unlock_irqrestore(&list->lock, flags);
2294}
2295EXPORT_SYMBOL(skb_queue_head);
2296
2297/**
2298 *	skb_queue_tail - queue a buffer at the list tail
2299 *	@list: list to use
2300 *	@newsk: buffer to queue
2301 *
2302 *	Queue a buffer at the tail of the list. This function takes the
2303 *	list lock and can be used safely with other locking &sk_buff functions
2304 *	safely.
2305 *
2306 *	A buffer cannot be placed on two lists at the same time.
2307 */
2308void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk)
2309{
2310	unsigned long flags;
2311
2312	spin_lock_irqsave(&list->lock, flags);
2313	__skb_queue_tail(list, newsk);
2314	spin_unlock_irqrestore(&list->lock, flags);
2315}
2316EXPORT_SYMBOL(skb_queue_tail);
2317
2318/**
2319 *	skb_unlink	-	remove a buffer from a list
2320 *	@skb: buffer to remove
2321 *	@list: list to use
2322 *
2323 *	Remove a packet from a list. The list locks are taken and this
2324 *	function is atomic with respect to other list locked calls
2325 *
2326 *	You must know what list the SKB is on.
2327 */
2328void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
2329{
2330	unsigned long flags;
2331
2332	spin_lock_irqsave(&list->lock, flags);
2333	__skb_unlink(skb, list);
2334	spin_unlock_irqrestore(&list->lock, flags);
2335}
2336EXPORT_SYMBOL(skb_unlink);
2337
2338/**
2339 *	skb_append	-	append a buffer
2340 *	@old: buffer to insert after
2341 *	@newsk: buffer to insert
2342 *	@list: list to use
2343 *
2344 *	Place a packet after a given packet in a list. The list locks are taken
2345 *	and this function is atomic with respect to other list locked calls.
2346 *	A buffer cannot be placed on two lists at the same time.
2347 */
2348void skb_append(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list)
2349{
2350	unsigned long flags;
2351
2352	spin_lock_irqsave(&list->lock, flags);
2353	__skb_queue_after(list, old, newsk);
2354	spin_unlock_irqrestore(&list->lock, flags);
2355}
2356EXPORT_SYMBOL(skb_append);
2357
2358/**
2359 *	skb_insert	-	insert a buffer
2360 *	@old: buffer to insert before
2361 *	@newsk: buffer to insert
2362 *	@list: list to use
2363 *
2364 *	Place a packet before a given packet in a list. The list locks are
2365 * 	taken and this function is atomic with respect to other list locked
2366 *	calls.
2367 *
2368 *	A buffer cannot be placed on two lists at the same time.
2369 */
2370void skb_insert(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list)
2371{
2372	unsigned long flags;
2373
2374	spin_lock_irqsave(&list->lock, flags);
2375	__skb_insert(newsk, old->prev, old, list);
2376	spin_unlock_irqrestore(&list->lock, flags);
2377}
2378EXPORT_SYMBOL(skb_insert);
2379
2380static inline void skb_split_inside_header(struct sk_buff *skb,
2381					   struct sk_buff* skb1,
2382					   const u32 len, const int pos)
2383{
2384	int i;
2385
2386	skb_copy_from_linear_data_offset(skb, len, skb_put(skb1, pos - len),
2387					 pos - len);
2388	/* And move data appendix as is. */
2389	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
2390		skb_shinfo(skb1)->frags[i] = skb_shinfo(skb)->frags[i];
2391
2392	skb_shinfo(skb1)->nr_frags = skb_shinfo(skb)->nr_frags;
2393	skb_shinfo(skb)->nr_frags  = 0;
2394	skb1->data_len		   = skb->data_len;
2395	skb1->len		   += skb1->data_len;
2396	skb->data_len		   = 0;
2397	skb->len		   = len;
2398	skb_set_tail_pointer(skb, len);
2399}
2400
2401static inline void skb_split_no_header(struct sk_buff *skb,
2402				       struct sk_buff* skb1,
2403				       const u32 len, int pos)
2404{
2405	int i, k = 0;
2406	const int nfrags = skb_shinfo(skb)->nr_frags;
2407
2408	skb_shinfo(skb)->nr_frags = 0;
2409	skb1->len		  = skb1->data_len = skb->len - len;
2410	skb->len		  = len;
2411	skb->data_len		  = len - pos;
2412
2413	for (i = 0; i < nfrags; i++) {
2414		int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
2415
2416		if (pos + size > len) {
2417			skb_shinfo(skb1)->frags[k] = skb_shinfo(skb)->frags[i];
2418
2419			if (pos < len) {
2420				/* Split frag.
2421				 * We have two variants in this case:
2422				 * 1. Move all the frag to the second
2423				 *    part, if it is possible. F.e.
2424				 *    this approach is mandatory for TUX,
2425				 *    where splitting is expensive.
2426				 * 2. Split is accurately. We make this.
2427				 */
2428				skb_frag_ref(skb, i);
2429				skb_shinfo(skb1)->frags[0].page_offset += len - pos;
2430				skb_frag_size_sub(&skb_shinfo(skb1)->frags[0], len - pos);
2431				skb_frag_size_set(&skb_shinfo(skb)->frags[i], len - pos);
2432				skb_shinfo(skb)->nr_frags++;
2433			}
2434			k++;
2435		} else
2436			skb_shinfo(skb)->nr_frags++;
2437		pos += size;
2438	}
2439	skb_shinfo(skb1)->nr_frags = k;
2440}
2441
2442/**
2443 * skb_split - Split fragmented skb to two parts at length len.
2444 * @skb: the buffer to split
2445 * @skb1: the buffer to receive the second part
2446 * @len: new length for skb
2447 */
2448void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len)
2449{
2450	int pos = skb_headlen(skb);
2451
2452	skb_shinfo(skb1)->tx_flags = skb_shinfo(skb)->tx_flags & SKBTX_SHARED_FRAG;
2453	if (len < pos)	/* Split line is inside header. */
2454		skb_split_inside_header(skb, skb1, len, pos);
2455	else		/* Second chunk has no header, nothing to copy. */
2456		skb_split_no_header(skb, skb1, len, pos);
2457}
2458EXPORT_SYMBOL(skb_split);
2459
2460/* Shifting from/to a cloned skb is a no-go.
2461 *
2462 * Caller cannot keep skb_shinfo related pointers past calling here!
2463 */
2464static int skb_prepare_for_shift(struct sk_buff *skb)
2465{
2466	return skb_cloned(skb) && pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
2467}
2468
2469/**
2470 * skb_shift - Shifts paged data partially from skb to another
2471 * @tgt: buffer into which tail data gets added
2472 * @skb: buffer from which the paged data comes from
2473 * @shiftlen: shift up to this many bytes
2474 *
2475 * Attempts to shift up to shiftlen worth of bytes, which may be less than
2476 * the length of the skb, from skb to tgt. Returns number bytes shifted.
2477 * It's up to caller to free skb if everything was shifted.
2478 *
2479 * If @tgt runs out of frags, the whole operation is aborted.
2480 *
2481 * Skb cannot include anything else but paged data while tgt is allowed
2482 * to have non-paged data as well.
2483 *
2484 * TODO: full sized shift could be optimized but that would need
2485 * specialized skb free'er to handle frags without up-to-date nr_frags.
2486 */
2487int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen)
2488{
2489	int from, to, merge, todo;
2490	struct skb_frag_struct *fragfrom, *fragto;
2491
2492	BUG_ON(shiftlen > skb->len);
2493	BUG_ON(skb_headlen(skb));	/* Would corrupt stream */
2494
2495	todo = shiftlen;
2496	from = 0;
2497	to = skb_shinfo(tgt)->nr_frags;
2498	fragfrom = &skb_shinfo(skb)->frags[from];
2499
2500	/* Actual merge is delayed until the point when we know we can
2501	 * commit all, so that we don't have to undo partial changes
2502	 */
2503	if (!to ||
2504	    !skb_can_coalesce(tgt, to, skb_frag_page(fragfrom),
2505			      fragfrom->page_offset)) {
2506		merge = -1;
2507	} else {
2508		merge = to - 1;
2509
2510		todo -= skb_frag_size(fragfrom);
2511		if (todo < 0) {
2512			if (skb_prepare_for_shift(skb) ||
2513			    skb_prepare_for_shift(tgt))
2514				return 0;
2515
2516			/* All previous frag pointers might be stale! */
2517			fragfrom = &skb_shinfo(skb)->frags[from];
2518			fragto = &skb_shinfo(tgt)->frags[merge];
2519
2520			skb_frag_size_add(fragto, shiftlen);
2521			skb_frag_size_sub(fragfrom, shiftlen);
2522			fragfrom->page_offset += shiftlen;
2523
2524			goto onlymerged;
2525		}
2526
2527		from++;
2528	}
2529
2530	/* Skip full, not-fitting skb to avoid expensive operations */
2531	if ((shiftlen == skb->len) &&
2532	    (skb_shinfo(skb)->nr_frags - from) > (MAX_SKB_FRAGS - to))
2533		return 0;
2534
2535	if (skb_prepare_for_shift(skb) || skb_prepare_for_shift(tgt))
2536		return 0;
2537
2538	while ((todo > 0) && (from < skb_shinfo(skb)->nr_frags)) {
2539		if (to == MAX_SKB_FRAGS)
2540			return 0;
2541
2542		fragfrom = &skb_shinfo(skb)->frags[from];
2543		fragto = &skb_shinfo(tgt)->frags[to];
2544
2545		if (todo >= skb_frag_size(fragfrom)) {
2546			*fragto = *fragfrom;
2547			todo -= skb_frag_size(fragfrom);
2548			from++;
2549			to++;
2550
2551		} else {
2552			__skb_frag_ref(fragfrom);
2553			fragto->page = fragfrom->page;
2554			fragto->page_offset = fragfrom->page_offset;
2555			skb_frag_size_set(fragto, todo);
2556
2557			fragfrom->page_offset += todo;
2558			skb_frag_size_sub(fragfrom, todo);
2559			todo = 0;
2560
2561			to++;
2562			break;
2563		}
2564	}
2565
2566	/* Ready to "commit" this state change to tgt */
2567	skb_shinfo(tgt)->nr_frags = to;
2568
2569	if (merge >= 0) {
2570		fragfrom = &skb_shinfo(skb)->frags[0];
2571		fragto = &skb_shinfo(tgt)->frags[merge];
2572
2573		skb_frag_size_add(fragto, skb_frag_size(fragfrom));
2574		__skb_frag_unref(fragfrom);
2575	}
2576
2577	/* Reposition in the original skb */
2578	to = 0;
2579	while (from < skb_shinfo(skb)->nr_frags)
2580		skb_shinfo(skb)->frags[to++] = skb_shinfo(skb)->frags[from++];
2581	skb_shinfo(skb)->nr_frags = to;
2582
2583	BUG_ON(todo > 0 && !skb_shinfo(skb)->nr_frags);
2584
2585onlymerged:
2586	/* Most likely the tgt won't ever need its checksum anymore, skb on
2587	 * the other hand might need it if it needs to be resent
2588	 */
2589	tgt->ip_summed = CHECKSUM_PARTIAL;
2590	skb->ip_summed = CHECKSUM_PARTIAL;
2591
2592	/* Yak, is it really working this way? Some helper please? */
2593	skb->len -= shiftlen;
2594	skb->data_len -= shiftlen;
2595	skb->truesize -= shiftlen;
2596	tgt->len += shiftlen;
2597	tgt->data_len += shiftlen;
2598	tgt->truesize += shiftlen;
2599
2600	return shiftlen;
2601}
2602
2603/**
2604 * skb_prepare_seq_read - Prepare a sequential read of skb data
2605 * @skb: the buffer to read
2606 * @from: lower offset of data to be read
2607 * @to: upper offset of data to be read
2608 * @st: state variable
2609 *
2610 * Initializes the specified state variable. Must be called before
2611 * invoking skb_seq_read() for the first time.
2612 */
2613void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from,
2614			  unsigned int to, struct skb_seq_state *st)
2615{
2616	st->lower_offset = from;
2617	st->upper_offset = to;
2618	st->root_skb = st->cur_skb = skb;
2619	st->frag_idx = st->stepped_offset = 0;
2620	st->frag_data = NULL;
2621}
2622EXPORT_SYMBOL(skb_prepare_seq_read);
2623
2624/**
2625 * skb_seq_read - Sequentially read skb data
2626 * @consumed: number of bytes consumed by the caller so far
2627 * @data: destination pointer for data to be returned
2628 * @st: state variable
2629 *
2630 * Reads a block of skb data at @consumed relative to the
2631 * lower offset specified to skb_prepare_seq_read(). Assigns
2632 * the head of the data block to @data and returns the length
2633 * of the block or 0 if the end of the skb data or the upper
2634 * offset has been reached.
2635 *
2636 * The caller is not required to consume all of the data
2637 * returned, i.e. @consumed is typically set to the number
2638 * of bytes already consumed and the next call to
2639 * skb_seq_read() will return the remaining part of the block.
2640 *
2641 * Note 1: The size of each block of data returned can be arbitrary,
2642 *       this limitation is the cost for zerocopy seqeuental
2643 *       reads of potentially non linear data.
2644 *
2645 * Note 2: Fragment lists within fragments are not implemented
2646 *       at the moment, state->root_skb could be replaced with
2647 *       a stack for this purpose.
2648 */
2649unsigned int skb_seq_read(unsigned int consumed, const u8 **data,
2650			  struct skb_seq_state *st)
2651{
2652	unsigned int block_limit, abs_offset = consumed + st->lower_offset;
2653	skb_frag_t *frag;
2654
2655	if (unlikely(abs_offset >= st->upper_offset)) {
2656		if (st->frag_data) {
2657			kunmap_atomic(st->frag_data);
2658			st->frag_data = NULL;
2659		}
2660		return 0;
2661	}
2662
2663next_skb:
2664	block_limit = skb_headlen(st->cur_skb) + st->stepped_offset;
2665
2666	if (abs_offset < block_limit && !st->frag_data) {
2667		*data = st->cur_skb->data + (abs_offset - st->stepped_offset);
2668		return block_limit - abs_offset;
2669	}
2670
2671	if (st->frag_idx == 0 && !st->frag_data)
2672		st->stepped_offset += skb_headlen(st->cur_skb);
2673
2674	while (st->frag_idx < skb_shinfo(st->cur_skb)->nr_frags) {
2675		frag = &skb_shinfo(st->cur_skb)->frags[st->frag_idx];
2676		block_limit = skb_frag_size(frag) + st->stepped_offset;
2677
2678		if (abs_offset < block_limit) {
2679			if (!st->frag_data)
2680				st->frag_data = kmap_atomic(skb_frag_page(frag));
2681
2682			*data = (u8 *) st->frag_data + frag->page_offset +
2683				(abs_offset - st->stepped_offset);
2684
2685			return block_limit - abs_offset;
2686		}
2687
2688		if (st->frag_data) {
2689			kunmap_atomic(st->frag_data);
2690			st->frag_data = NULL;
2691		}
2692
2693		st->frag_idx++;
2694		st->stepped_offset += skb_frag_size(frag);
2695	}
2696
2697	if (st->frag_data) {
2698		kunmap_atomic(st->frag_data);
2699		st->frag_data = NULL;
2700	}
2701
2702	if (st->root_skb == st->cur_skb && skb_has_frag_list(st->root_skb)) {
2703		st->cur_skb = skb_shinfo(st->root_skb)->frag_list;
2704		st->frag_idx = 0;
2705		goto next_skb;
2706	} else if (st->cur_skb->next) {
2707		st->cur_skb = st->cur_skb->next;
2708		st->frag_idx = 0;
2709		goto next_skb;
2710	}
2711
2712	return 0;
2713}
2714EXPORT_SYMBOL(skb_seq_read);
2715
2716/**
2717 * skb_abort_seq_read - Abort a sequential read of skb data
2718 * @st: state variable
2719 *
2720 * Must be called if skb_seq_read() was not called until it
2721 * returned 0.
2722 */
2723void skb_abort_seq_read(struct skb_seq_state *st)
2724{
2725	if (st->frag_data)
2726		kunmap_atomic(st->frag_data);
2727}
2728EXPORT_SYMBOL(skb_abort_seq_read);
2729
2730#define TS_SKB_CB(state)	((struct skb_seq_state *) &((state)->cb))
2731
2732static unsigned int skb_ts_get_next_block(unsigned int offset, const u8 **text,
2733					  struct ts_config *conf,
2734					  struct ts_state *state)
2735{
2736	return skb_seq_read(offset, text, TS_SKB_CB(state));
2737}
2738
2739static void skb_ts_finish(struct ts_config *conf, struct ts_state *state)
2740{
2741	skb_abort_seq_read(TS_SKB_CB(state));
2742}
2743
2744/**
2745 * skb_find_text - Find a text pattern in skb data
2746 * @skb: the buffer to look in
2747 * @from: search offset
2748 * @to: search limit
2749 * @config: textsearch configuration
2750 * @state: uninitialized textsearch state variable
2751 *
2752 * Finds a pattern in the skb data according to the specified
2753 * textsearch configuration. Use textsearch_next() to retrieve
2754 * subsequent occurrences of the pattern. Returns the offset
2755 * to the first occurrence or UINT_MAX if no match was found.
2756 */
2757unsigned int skb_find_text(struct sk_buff *skb, unsigned int from,
2758			   unsigned int to, struct ts_config *config,
2759			   struct ts_state *state)
2760{
2761	unsigned int ret;
2762
2763	config->get_next_block = skb_ts_get_next_block;
2764	config->finish = skb_ts_finish;
2765
2766	skb_prepare_seq_read(skb, from, to, TS_SKB_CB(state));
2767
2768	ret = textsearch_find(config, state);
2769	return (ret <= to - from ? ret : UINT_MAX);
2770}
2771EXPORT_SYMBOL(skb_find_text);
2772
2773/**
2774 * skb_append_datato_frags - append the user data to a skb
2775 * @sk: sock  structure
2776 * @skb: skb structure to be appened with user data.
2777 * @getfrag: call back function to be used for getting the user data
2778 * @from: pointer to user message iov
2779 * @length: length of the iov message
2780 *
2781 * Description: This procedure append the user data in the fragment part
2782 * of the skb if any page alloc fails user this procedure returns  -ENOMEM
2783 */
2784int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb,
2785			int (*getfrag)(void *from, char *to, int offset,
2786					int len, int odd, struct sk_buff *skb),
2787			void *from, int length)
2788{
2789	int frg_cnt = skb_shinfo(skb)->nr_frags;
2790	int copy;
 
 
2791	int offset = 0;
2792	int ret;
2793	struct page_frag *pfrag = &current->task_frag;
2794
2795	do {
2796		/* Return error if we don't have space for new frag */
 
2797		if (frg_cnt >= MAX_SKB_FRAGS)
2798			return -EMSGSIZE;
 
 
 
2799
2800		if (!sk_page_frag_refill(sk, pfrag))
 
 
 
2801			return -ENOMEM;
2802
 
 
 
 
 
 
 
 
 
2803		/* copy the user data to page */
2804		copy = min_t(int, length, pfrag->size - pfrag->offset);
 
2805
2806		ret = getfrag(from, page_address(pfrag->page) + pfrag->offset,
2807			      offset, copy, 0, skb);
2808		if (ret < 0)
2809			return -EFAULT;
2810
2811		/* copy was successful so update the size parameters */
2812		skb_fill_page_desc(skb, frg_cnt, pfrag->page, pfrag->offset,
2813				   copy);
2814		frg_cnt++;
2815		pfrag->offset += copy;
2816		get_page(pfrag->page);
2817
2818		skb->truesize += copy;
2819		atomic_add(copy, &sk->sk_wmem_alloc);
2820		skb->len += copy;
2821		skb->data_len += copy;
2822		offset += copy;
2823		length -= copy;
2824
2825	} while (length > 0);
2826
2827	return 0;
2828}
2829EXPORT_SYMBOL(skb_append_datato_frags);
2830
2831/**
2832 *	skb_pull_rcsum - pull skb and update receive checksum
2833 *	@skb: buffer to update
2834 *	@len: length of data pulled
2835 *
2836 *	This function performs an skb_pull on the packet and updates
2837 *	the CHECKSUM_COMPLETE checksum.  It should be used on
2838 *	receive path processing instead of skb_pull unless you know
2839 *	that the checksum difference is zero (e.g., a valid IP header)
2840 *	or you are setting ip_summed to CHECKSUM_NONE.
2841 */
2842unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len)
2843{
2844	BUG_ON(len > skb->len);
2845	skb->len -= len;
2846	BUG_ON(skb->len < skb->data_len);
2847	skb_postpull_rcsum(skb, skb->data, len);
2848	return skb->data += len;
2849}
2850EXPORT_SYMBOL_GPL(skb_pull_rcsum);
2851
2852/**
2853 *	skb_segment - Perform protocol segmentation on skb.
2854 *	@head_skb: buffer to segment
2855 *	@features: features for the output path (see dev->features)
2856 *
2857 *	This function performs segmentation on the given skb.  It returns
2858 *	a pointer to the first in a list of new skbs for the segments.
2859 *	In case of error it returns ERR_PTR(err).
2860 */
2861struct sk_buff *skb_segment(struct sk_buff *head_skb,
2862			    netdev_features_t features)
2863{
2864	struct sk_buff *segs = NULL;
2865	struct sk_buff *tail = NULL;
2866	struct sk_buff *list_skb = skb_shinfo(head_skb)->frag_list;
2867	skb_frag_t *frag = skb_shinfo(head_skb)->frags;
2868	unsigned int mss = skb_shinfo(head_skb)->gso_size;
2869	unsigned int doffset = head_skb->data - skb_mac_header(head_skb);
2870	struct sk_buff *frag_skb = head_skb;
2871	unsigned int offset = doffset;
2872	unsigned int tnl_hlen = skb_tnl_header_len(head_skb);
2873	unsigned int headroom;
2874	unsigned int len;
2875	__be16 proto;
2876	bool csum;
2877	int sg = !!(features & NETIF_F_SG);
2878	int nfrags = skb_shinfo(head_skb)->nr_frags;
2879	int err = -ENOMEM;
2880	int i = 0;
2881	int pos;
2882	int dummy;
2883
2884	proto = skb_network_protocol(head_skb, &dummy);
2885	if (unlikely(!proto))
2886		return ERR_PTR(-EINVAL);
2887
2888	csum = !!can_checksum_protocol(features, proto);
2889	__skb_push(head_skb, doffset);
2890	headroom = skb_headroom(head_skb);
2891	pos = skb_headlen(head_skb);
2892
2893	do {
2894		struct sk_buff *nskb;
2895		skb_frag_t *nskb_frag;
2896		int hsize;
2897		int size;
2898
2899		len = head_skb->len - offset;
2900		if (len > mss)
2901			len = mss;
2902
2903		hsize = skb_headlen(head_skb) - offset;
2904		if (hsize < 0)
2905			hsize = 0;
2906		if (hsize > len || !sg)
2907			hsize = len;
2908
2909		if (!hsize && i >= nfrags && skb_headlen(list_skb) &&
2910		    (skb_headlen(list_skb) == len || sg)) {
2911			BUG_ON(skb_headlen(list_skb) > len);
2912
2913			i = 0;
2914			nfrags = skb_shinfo(list_skb)->nr_frags;
2915			frag = skb_shinfo(list_skb)->frags;
2916			frag_skb = list_skb;
2917			pos += skb_headlen(list_skb);
2918
2919			while (pos < offset + len) {
2920				BUG_ON(i >= nfrags);
2921
2922				size = skb_frag_size(frag);
2923				if (pos + size > offset + len)
2924					break;
2925
2926				i++;
2927				pos += size;
2928				frag++;
2929			}
2930
2931			nskb = skb_clone(list_skb, GFP_ATOMIC);
2932			list_skb = list_skb->next;
 
2933
2934			if (unlikely(!nskb))
2935				goto err;
2936
2937			if (unlikely(pskb_trim(nskb, len))) {
2938				kfree_skb(nskb);
2939				goto err;
2940			}
2941
2942			hsize = skb_end_offset(nskb);
2943			if (skb_cow_head(nskb, doffset + headroom)) {
2944				kfree_skb(nskb);
2945				goto err;
2946			}
2947
2948			nskb->truesize += skb_end_offset(nskb) - hsize;
2949			skb_release_head_state(nskb);
2950			__skb_push(nskb, doffset);
2951		} else {
2952			nskb = __alloc_skb(hsize + doffset + headroom,
2953					   GFP_ATOMIC, skb_alloc_rx_flag(head_skb),
2954					   NUMA_NO_NODE);
2955
2956			if (unlikely(!nskb))
2957				goto err;
2958
2959			skb_reserve(nskb, headroom);
2960			__skb_put(nskb, doffset);
2961		}
2962
2963		if (segs)
2964			tail->next = nskb;
2965		else
2966			segs = nskb;
2967		tail = nskb;
2968
2969		__copy_skb_header(nskb, head_skb);
2970		nskb->mac_len = head_skb->mac_len;
2971
2972		skb_headers_offset_update(nskb, skb_headroom(nskb) - headroom);
2973
2974		skb_copy_from_linear_data_offset(head_skb, -tnl_hlen,
2975						 nskb->data - tnl_hlen,
2976						 doffset + tnl_hlen);
 
 
 
 
 
 
2977
2978		if (nskb->len == len + doffset)
2979			goto perform_csum_check;
2980
2981		if (!sg) {
2982			nskb->ip_summed = CHECKSUM_NONE;
2983			nskb->csum = skb_copy_and_csum_bits(head_skb, offset,
2984							    skb_put(nskb, len),
2985							    len, 0);
2986			continue;
2987		}
2988
2989		nskb_frag = skb_shinfo(nskb)->frags;
2990
2991		skb_copy_from_linear_data_offset(head_skb, offset,
2992						 skb_put(nskb, hsize), hsize);
2993
2994		skb_shinfo(nskb)->tx_flags = skb_shinfo(head_skb)->tx_flags &
2995			SKBTX_SHARED_FRAG;
2996
2997		while (pos < offset + len) {
2998			if (i >= nfrags) {
2999				BUG_ON(skb_headlen(list_skb));
3000
3001				i = 0;
3002				nfrags = skb_shinfo(list_skb)->nr_frags;
3003				frag = skb_shinfo(list_skb)->frags;
3004				frag_skb = list_skb;
3005
3006				BUG_ON(!nfrags);
3007
3008				list_skb = list_skb->next;
3009			}
3010
3011			if (unlikely(skb_shinfo(nskb)->nr_frags >=
3012				     MAX_SKB_FRAGS)) {
3013				net_warn_ratelimited(
3014					"skb_segment: too many frags: %u %u\n",
3015					pos, mss);
3016				goto err;
3017			}
3018
3019			if (unlikely(skb_orphan_frags(frag_skb, GFP_ATOMIC)))
3020				goto err;
3021
3022			*nskb_frag = *frag;
3023			__skb_frag_ref(nskb_frag);
3024			size = skb_frag_size(nskb_frag);
3025
3026			if (pos < offset) {
3027				nskb_frag->page_offset += offset - pos;
3028				skb_frag_size_sub(nskb_frag, offset - pos);
3029			}
3030
3031			skb_shinfo(nskb)->nr_frags++;
3032
3033			if (pos + size <= offset + len) {
3034				i++;
3035				frag++;
3036				pos += size;
3037			} else {
3038				skb_frag_size_sub(nskb_frag, pos + size - (offset + len));
3039				goto skip_fraglist;
3040			}
3041
3042			nskb_frag++;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3043		}
3044
3045skip_fraglist:
3046		nskb->data_len = len - hsize;
3047		nskb->len += nskb->data_len;
3048		nskb->truesize += nskb->data_len;
3049
3050perform_csum_check:
3051		if (!csum) {
3052			nskb->csum = skb_checksum(nskb, doffset,
3053						  nskb->len - doffset, 0);
3054			nskb->ip_summed = CHECKSUM_NONE;
3055		}
3056	} while ((offset += len) < head_skb->len);
3057
3058	return segs;
3059
3060err:
3061	kfree_skb_list(segs);
 
 
 
3062	return ERR_PTR(err);
3063}
3064EXPORT_SYMBOL_GPL(skb_segment);
3065
3066int skb_gro_receive(struct sk_buff **head, struct sk_buff *skb)
3067{
3068	struct skb_shared_info *pinfo, *skbinfo = skb_shinfo(skb);
 
 
 
 
 
3069	unsigned int offset = skb_gro_offset(skb);
3070	unsigned int headlen = skb_headlen(skb);
3071	struct sk_buff *nskb, *lp, *p = *head;
3072	unsigned int len = skb_gro_len(skb);
3073	unsigned int delta_truesize;
3074	unsigned int headroom;
3075
3076	if (unlikely(p->len + len >= 65536))
3077		return -E2BIG;
3078
3079	lp = NAPI_GRO_CB(p)->last;
3080	pinfo = skb_shinfo(lp);
3081
3082	if (headlen <= offset) {
3083		skb_frag_t *frag;
3084		skb_frag_t *frag2;
3085		int i = skbinfo->nr_frags;
3086		int nr_frags = pinfo->nr_frags + i;
3087
 
 
3088		if (nr_frags > MAX_SKB_FRAGS)
3089			goto merge;
3090
3091		offset -= headlen;
3092		pinfo->nr_frags = nr_frags;
3093		skbinfo->nr_frags = 0;
3094
3095		frag = pinfo->frags + nr_frags;
3096		frag2 = skbinfo->frags + i;
3097		do {
3098			*--frag = *--frag2;
3099		} while (--i);
3100
3101		frag->page_offset += offset;
3102		skb_frag_size_sub(frag, offset);
3103
3104		/* all fragments truesize : remove (head size + sk_buff) */
3105		delta_truesize = skb->truesize -
3106				 SKB_TRUESIZE(skb_end_offset(skb));
3107
3108		skb->truesize -= skb->data_len;
3109		skb->len -= skb->data_len;
3110		skb->data_len = 0;
3111
3112		NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE;
3113		goto done;
3114	} else if (skb->head_frag) {
3115		int nr_frags = pinfo->nr_frags;
3116		skb_frag_t *frag = pinfo->frags + nr_frags;
3117		struct page *page = virt_to_head_page(skb->head);
3118		unsigned int first_size = headlen - offset;
3119		unsigned int first_offset;
3120
3121		if (nr_frags + 1 + skbinfo->nr_frags > MAX_SKB_FRAGS)
3122			goto merge;
3123
3124		first_offset = skb->data -
3125			       (unsigned char *)page_address(page) +
3126			       offset;
3127
3128		pinfo->nr_frags = nr_frags + 1 + skbinfo->nr_frags;
3129
3130		frag->page.p	  = page;
3131		frag->page_offset = first_offset;
3132		skb_frag_size_set(frag, first_size);
3133
3134		memcpy(frag + 1, skbinfo->frags, sizeof(*frag) * skbinfo->nr_frags);
3135		/* We dont need to clear skbinfo->nr_frags here */
3136
3137		delta_truesize = skb->truesize - SKB_DATA_ALIGN(sizeof(struct sk_buff));
3138		NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE_STOLEN_HEAD;
3139		goto done;
3140	}
3141	if (pinfo->frag_list)
3142		goto merge;
3143	if (skb_gro_len(p) != pinfo->gso_size)
3144		return -E2BIG;
3145
3146	headroom = skb_headroom(p);
3147	nskb = alloc_skb(headroom + skb_gro_offset(p), GFP_ATOMIC);
3148	if (unlikely(!nskb))
3149		return -ENOMEM;
3150
3151	__copy_skb_header(nskb, p);
3152	nskb->mac_len = p->mac_len;
3153
3154	skb_reserve(nskb, headroom);
3155	__skb_put(nskb, skb_gro_offset(p));
3156
3157	skb_set_mac_header(nskb, skb_mac_header(p) - p->data);
3158	skb_set_network_header(nskb, skb_network_offset(p));
3159	skb_set_transport_header(nskb, skb_transport_offset(p));
3160
3161	__skb_pull(p, skb_gro_offset(p));
3162	memcpy(skb_mac_header(nskb), skb_mac_header(p),
3163	       p->data - skb_mac_header(p));
3164
 
3165	skb_shinfo(nskb)->frag_list = p;
3166	skb_shinfo(nskb)->gso_size = pinfo->gso_size;
3167	pinfo->gso_size = 0;
3168	skb_header_release(p);
3169	NAPI_GRO_CB(nskb)->last = p;
3170
3171	nskb->data_len += p->len;
3172	nskb->truesize += p->truesize;
3173	nskb->len += p->len;
3174
3175	*head = nskb;
3176	nskb->next = p->next;
3177	p->next = NULL;
3178
3179	p = nskb;
3180
3181merge:
3182	delta_truesize = skb->truesize;
3183	if (offset > headlen) {
3184		unsigned int eat = offset - headlen;
3185
3186		skbinfo->frags[0].page_offset += eat;
3187		skb_frag_size_sub(&skbinfo->frags[0], eat);
3188		skb->data_len -= eat;
3189		skb->len -= eat;
3190		offset = headlen;
3191	}
3192
3193	__skb_pull(skb, offset);
3194
3195	if (NAPI_GRO_CB(p)->last == p)
3196		skb_shinfo(p)->frag_list = skb;
3197	else
3198		NAPI_GRO_CB(p)->last->next = skb;
3199	NAPI_GRO_CB(p)->last = skb;
3200	skb_header_release(skb);
3201	lp = p;
3202
3203done:
3204	NAPI_GRO_CB(p)->count++;
3205	p->data_len += len;
3206	p->truesize += delta_truesize;
3207	p->len += len;
3208	if (lp != p) {
3209		lp->data_len += len;
3210		lp->truesize += delta_truesize;
3211		lp->len += len;
3212	}
3213	NAPI_GRO_CB(skb)->same_flow = 1;
3214	return 0;
3215}
3216EXPORT_SYMBOL_GPL(skb_gro_receive);
3217
3218void __init skb_init(void)
3219{
3220	skbuff_head_cache = kmem_cache_create("skbuff_head_cache",
3221					      sizeof(struct sk_buff),
3222					      0,
3223					      SLAB_HWCACHE_ALIGN|SLAB_PANIC,
3224					      NULL);
3225	skbuff_fclone_cache = kmem_cache_create("skbuff_fclone_cache",
3226						(2*sizeof(struct sk_buff)) +
3227						sizeof(atomic_t),
3228						0,
3229						SLAB_HWCACHE_ALIGN|SLAB_PANIC,
3230						NULL);
3231}
3232
3233/**
3234 *	skb_to_sgvec - Fill a scatter-gather list from a socket buffer
3235 *	@skb: Socket buffer containing the buffers to be mapped
3236 *	@sg: The scatter-gather list to map into
3237 *	@offset: The offset into the buffer's contents to start mapping
3238 *	@len: Length of buffer space to be mapped
3239 *
3240 *	Fill the specified scatter-gather list with mappings/pointers into a
3241 *	region of the buffer space attached to a socket buffer.
3242 */
3243static int
3244__skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
3245{
3246	int start = skb_headlen(skb);
3247	int i, copy = start - offset;
3248	struct sk_buff *frag_iter;
3249	int elt = 0;
3250
3251	if (copy > 0) {
3252		if (copy > len)
3253			copy = len;
3254		sg_set_buf(sg, skb->data + offset, copy);
3255		elt++;
3256		if ((len -= copy) == 0)
3257			return elt;
3258		offset += copy;
3259	}
3260
3261	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
3262		int end;
3263
3264		WARN_ON(start > offset + len);
3265
3266		end = start + skb_frag_size(&skb_shinfo(skb)->frags[i]);
3267		if ((copy = end - offset) > 0) {
3268			skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
3269
3270			if (copy > len)
3271				copy = len;
3272			sg_set_page(&sg[elt], skb_frag_page(frag), copy,
3273					frag->page_offset+offset-start);
3274			elt++;
3275			if (!(len -= copy))
3276				return elt;
3277			offset += copy;
3278		}
3279		start = end;
3280	}
3281
3282	skb_walk_frags(skb, frag_iter) {
3283		int end;
3284
3285		WARN_ON(start > offset + len);
3286
3287		end = start + frag_iter->len;
3288		if ((copy = end - offset) > 0) {
3289			if (copy > len)
3290				copy = len;
3291			elt += __skb_to_sgvec(frag_iter, sg+elt, offset - start,
3292					      copy);
3293			if ((len -= copy) == 0)
3294				return elt;
3295			offset += copy;
3296		}
3297		start = end;
3298	}
3299	BUG_ON(len);
3300	return elt;
3301}
3302
3303/* As compared with skb_to_sgvec, skb_to_sgvec_nomark only map skb to given
3304 * sglist without mark the sg which contain last skb data as the end.
3305 * So the caller can mannipulate sg list as will when padding new data after
3306 * the first call without calling sg_unmark_end to expend sg list.
3307 *
3308 * Scenario to use skb_to_sgvec_nomark:
3309 * 1. sg_init_table
3310 * 2. skb_to_sgvec_nomark(payload1)
3311 * 3. skb_to_sgvec_nomark(payload2)
3312 *
3313 * This is equivalent to:
3314 * 1. sg_init_table
3315 * 2. skb_to_sgvec(payload1)
3316 * 3. sg_unmark_end
3317 * 4. skb_to_sgvec(payload2)
3318 *
3319 * When mapping mutilple payload conditionally, skb_to_sgvec_nomark
3320 * is more preferable.
3321 */
3322int skb_to_sgvec_nomark(struct sk_buff *skb, struct scatterlist *sg,
3323			int offset, int len)
3324{
3325	return __skb_to_sgvec(skb, sg, offset, len);
3326}
3327EXPORT_SYMBOL_GPL(skb_to_sgvec_nomark);
3328
3329int skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
3330{
3331	int nsg = __skb_to_sgvec(skb, sg, offset, len);
3332
3333	sg_mark_end(&sg[nsg - 1]);
3334
3335	return nsg;
3336}
3337EXPORT_SYMBOL_GPL(skb_to_sgvec);
3338
3339/**
3340 *	skb_cow_data - Check that a socket buffer's data buffers are writable
3341 *	@skb: The socket buffer to check.
3342 *	@tailbits: Amount of trailing space to be added
3343 *	@trailer: Returned pointer to the skb where the @tailbits space begins
3344 *
3345 *	Make sure that the data buffers attached to a socket buffer are
3346 *	writable. If they are not, private copies are made of the data buffers
3347 *	and the socket buffer is set to use these instead.
3348 *
3349 *	If @tailbits is given, make sure that there is space to write @tailbits
3350 *	bytes of data beyond current end of socket buffer.  @trailer will be
3351 *	set to point to the skb in which this space begins.
3352 *
3353 *	The number of scatterlist elements required to completely map the
3354 *	COW'd and extended socket buffer will be returned.
3355 */
3356int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer)
3357{
3358	int copyflag;
3359	int elt;
3360	struct sk_buff *skb1, **skb_p;
3361
3362	/* If skb is cloned or its head is paged, reallocate
3363	 * head pulling out all the pages (pages are considered not writable
3364	 * at the moment even if they are anonymous).
3365	 */
3366	if ((skb_cloned(skb) || skb_shinfo(skb)->nr_frags) &&
3367	    __pskb_pull_tail(skb, skb_pagelen(skb)-skb_headlen(skb)) == NULL)
3368		return -ENOMEM;
3369
3370	/* Easy case. Most of packets will go this way. */
3371	if (!skb_has_frag_list(skb)) {
3372		/* A little of trouble, not enough of space for trailer.
3373		 * This should not happen, when stack is tuned to generate
3374		 * good frames. OK, on miss we reallocate and reserve even more
3375		 * space, 128 bytes is fair. */
3376
3377		if (skb_tailroom(skb) < tailbits &&
3378		    pskb_expand_head(skb, 0, tailbits-skb_tailroom(skb)+128, GFP_ATOMIC))
3379			return -ENOMEM;
3380
3381		/* Voila! */
3382		*trailer = skb;
3383		return 1;
3384	}
3385
3386	/* Misery. We are in troubles, going to mincer fragments... */
3387
3388	elt = 1;
3389	skb_p = &skb_shinfo(skb)->frag_list;
3390	copyflag = 0;
3391
3392	while ((skb1 = *skb_p) != NULL) {
3393		int ntail = 0;
3394
3395		/* The fragment is partially pulled by someone,
3396		 * this can happen on input. Copy it and everything
3397		 * after it. */
3398
3399		if (skb_shared(skb1))
3400			copyflag = 1;
3401
3402		/* If the skb is the last, worry about trailer. */
3403
3404		if (skb1->next == NULL && tailbits) {
3405			if (skb_shinfo(skb1)->nr_frags ||
3406			    skb_has_frag_list(skb1) ||
3407			    skb_tailroom(skb1) < tailbits)
3408				ntail = tailbits + 128;
3409		}
3410
3411		if (copyflag ||
3412		    skb_cloned(skb1) ||
3413		    ntail ||
3414		    skb_shinfo(skb1)->nr_frags ||
3415		    skb_has_frag_list(skb1)) {
3416			struct sk_buff *skb2;
3417
3418			/* Fuck, we are miserable poor guys... */
3419			if (ntail == 0)
3420				skb2 = skb_copy(skb1, GFP_ATOMIC);
3421			else
3422				skb2 = skb_copy_expand(skb1,
3423						       skb_headroom(skb1),
3424						       ntail,
3425						       GFP_ATOMIC);
3426			if (unlikely(skb2 == NULL))
3427				return -ENOMEM;
3428
3429			if (skb1->sk)
3430				skb_set_owner_w(skb2, skb1->sk);
3431
3432			/* Looking around. Are we still alive?
3433			 * OK, link new skb, drop old one */
3434
3435			skb2->next = skb1->next;
3436			*skb_p = skb2;
3437			kfree_skb(skb1);
3438			skb1 = skb2;
3439		}
3440		elt++;
3441		*trailer = skb1;
3442		skb_p = &skb1->next;
3443	}
3444
3445	return elt;
3446}
3447EXPORT_SYMBOL_GPL(skb_cow_data);
3448
3449static void sock_rmem_free(struct sk_buff *skb)
3450{
3451	struct sock *sk = skb->sk;
3452
3453	atomic_sub(skb->truesize, &sk->sk_rmem_alloc);
3454}
3455
3456/*
3457 * Note: We dont mem charge error packets (no sk_forward_alloc changes)
3458 */
3459int sock_queue_err_skb(struct sock *sk, struct sk_buff *skb)
3460{
 
 
3461	if (atomic_read(&sk->sk_rmem_alloc) + skb->truesize >=
3462	    (unsigned int)sk->sk_rcvbuf)
3463		return -ENOMEM;
3464
3465	skb_orphan(skb);
3466	skb->sk = sk;
3467	skb->destructor = sock_rmem_free;
3468	atomic_add(skb->truesize, &sk->sk_rmem_alloc);
3469
3470	/* before exiting rcu section, make sure dst is refcounted */
3471	skb_dst_force(skb);
3472
3473	skb_queue_tail(&sk->sk_error_queue, skb);
3474	if (!sock_flag(sk, SOCK_DEAD))
3475		sk->sk_data_ready(sk);
3476	return 0;
3477}
3478EXPORT_SYMBOL(sock_queue_err_skb);
3479
3480void skb_tstamp_tx(struct sk_buff *orig_skb,
3481		struct skb_shared_hwtstamps *hwtstamps)
3482{
3483	struct sock *sk = orig_skb->sk;
3484	struct sock_exterr_skb *serr;
3485	struct sk_buff *skb;
3486	int err;
3487
3488	if (!sk)
3489		return;
3490
 
 
 
 
3491	if (hwtstamps) {
3492		*skb_hwtstamps(orig_skb) =
3493			*hwtstamps;
3494	} else {
3495		/*
3496		 * no hardware time stamps available,
3497		 * so keep the shared tx_flags and only
3498		 * store software time stamp
3499		 */
3500		orig_skb->tstamp = ktime_get_real();
3501	}
3502
3503	skb = skb_clone(orig_skb, GFP_ATOMIC);
3504	if (!skb)
3505		return;
3506
3507	serr = SKB_EXT_ERR(skb);
3508	memset(serr, 0, sizeof(*serr));
3509	serr->ee.ee_errno = ENOMSG;
3510	serr->ee.ee_origin = SO_EE_ORIGIN_TIMESTAMPING;
3511
3512	err = sock_queue_err_skb(sk, skb);
3513
3514	if (err)
3515		kfree_skb(skb);
3516}
3517EXPORT_SYMBOL_GPL(skb_tstamp_tx);
3518
3519void skb_complete_wifi_ack(struct sk_buff *skb, bool acked)
3520{
3521	struct sock *sk = skb->sk;
3522	struct sock_exterr_skb *serr;
3523	int err;
3524
3525	skb->wifi_acked_valid = 1;
3526	skb->wifi_acked = acked;
3527
3528	serr = SKB_EXT_ERR(skb);
3529	memset(serr, 0, sizeof(*serr));
3530	serr->ee.ee_errno = ENOMSG;
3531	serr->ee.ee_origin = SO_EE_ORIGIN_TXSTATUS;
3532
3533	err = sock_queue_err_skb(sk, skb);
3534	if (err)
3535		kfree_skb(skb);
3536}
3537EXPORT_SYMBOL_GPL(skb_complete_wifi_ack);
3538
3539
3540/**
3541 * skb_partial_csum_set - set up and verify partial csum values for packet
3542 * @skb: the skb to set
3543 * @start: the number of bytes after skb->data to start checksumming.
3544 * @off: the offset from start to place the checksum.
3545 *
3546 * For untrusted partially-checksummed packets, we need to make sure the values
3547 * for skb->csum_start and skb->csum_offset are valid so we don't oops.
3548 *
3549 * This function checks and sets those values and skb->ip_summed: if this
3550 * returns false you should drop the packet.
3551 */
3552bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off)
3553{
3554	if (unlikely(start > skb_headlen(skb)) ||
3555	    unlikely((int)start + off > skb_headlen(skb) - 2)) {
3556		net_warn_ratelimited("bad partial csum: csum=%u/%u len=%u\n",
3557				     start, off, skb_headlen(skb));
3558		return false;
3559	}
3560	skb->ip_summed = CHECKSUM_PARTIAL;
3561	skb->csum_start = skb_headroom(skb) + start;
3562	skb->csum_offset = off;
3563	skb_set_transport_header(skb, start);
3564	return true;
3565}
3566EXPORT_SYMBOL_GPL(skb_partial_csum_set);
3567
3568static int skb_maybe_pull_tail(struct sk_buff *skb, unsigned int len,
3569			       unsigned int max)
3570{
3571	if (skb_headlen(skb) >= len)
3572		return 0;
3573
3574	/* If we need to pullup then pullup to the max, so we
3575	 * won't need to do it again.
3576	 */
3577	if (max > skb->len)
3578		max = skb->len;
3579
3580	if (__pskb_pull_tail(skb, max - skb_headlen(skb)) == NULL)
3581		return -ENOMEM;
3582
3583	if (skb_headlen(skb) < len)
3584		return -EPROTO;
3585
3586	return 0;
3587}
3588
3589#define MAX_TCP_HDR_LEN (15 * 4)
3590
3591static __sum16 *skb_checksum_setup_ip(struct sk_buff *skb,
3592				      typeof(IPPROTO_IP) proto,
3593				      unsigned int off)
3594{
3595	switch (proto) {
3596		int err;
3597
3598	case IPPROTO_TCP:
3599		err = skb_maybe_pull_tail(skb, off + sizeof(struct tcphdr),
3600					  off + MAX_TCP_HDR_LEN);
3601		if (!err && !skb_partial_csum_set(skb, off,
3602						  offsetof(struct tcphdr,
3603							   check)))
3604			err = -EPROTO;
3605		return err ? ERR_PTR(err) : &tcp_hdr(skb)->check;
3606
3607	case IPPROTO_UDP:
3608		err = skb_maybe_pull_tail(skb, off + sizeof(struct udphdr),
3609					  off + sizeof(struct udphdr));
3610		if (!err && !skb_partial_csum_set(skb, off,
3611						  offsetof(struct udphdr,
3612							   check)))
3613			err = -EPROTO;
3614		return err ? ERR_PTR(err) : &udp_hdr(skb)->check;
3615	}
3616
3617	return ERR_PTR(-EPROTO);
3618}
3619
3620/* This value should be large enough to cover a tagged ethernet header plus
3621 * maximally sized IP and TCP or UDP headers.
3622 */
3623#define MAX_IP_HDR_LEN 128
3624
3625static int skb_checksum_setup_ipv4(struct sk_buff *skb, bool recalculate)
3626{
3627	unsigned int off;
3628	bool fragment;
3629	__sum16 *csum;
3630	int err;
3631
3632	fragment = false;
3633
3634	err = skb_maybe_pull_tail(skb,
3635				  sizeof(struct iphdr),
3636				  MAX_IP_HDR_LEN);
3637	if (err < 0)
3638		goto out;
3639
3640	if (ip_hdr(skb)->frag_off & htons(IP_OFFSET | IP_MF))
3641		fragment = true;
3642
3643	off = ip_hdrlen(skb);
3644
3645	err = -EPROTO;
3646
3647	if (fragment)
3648		goto out;
3649
3650	csum = skb_checksum_setup_ip(skb, ip_hdr(skb)->protocol, off);
3651	if (IS_ERR(csum))
3652		return PTR_ERR(csum);
3653
3654	if (recalculate)
3655		*csum = ~csum_tcpudp_magic(ip_hdr(skb)->saddr,
3656					   ip_hdr(skb)->daddr,
3657					   skb->len - off,
3658					   ip_hdr(skb)->protocol, 0);
3659	err = 0;
3660
3661out:
3662	return err;
3663}
3664
3665/* This value should be large enough to cover a tagged ethernet header plus
3666 * an IPv6 header, all options, and a maximal TCP or UDP header.
3667 */
3668#define MAX_IPV6_HDR_LEN 256
3669
3670#define OPT_HDR(type, skb, off) \
3671	(type *)(skb_network_header(skb) + (off))
3672
3673static int skb_checksum_setup_ipv6(struct sk_buff *skb, bool recalculate)
3674{
3675	int err;
3676	u8 nexthdr;
3677	unsigned int off;
3678	unsigned int len;
3679	bool fragment;
3680	bool done;
3681	__sum16 *csum;
3682
3683	fragment = false;
3684	done = false;
3685
3686	off = sizeof(struct ipv6hdr);
3687
3688	err = skb_maybe_pull_tail(skb, off, MAX_IPV6_HDR_LEN);
3689	if (err < 0)
3690		goto out;
3691
3692	nexthdr = ipv6_hdr(skb)->nexthdr;
3693
3694	len = sizeof(struct ipv6hdr) + ntohs(ipv6_hdr(skb)->payload_len);
3695	while (off <= len && !done) {
3696		switch (nexthdr) {
3697		case IPPROTO_DSTOPTS:
3698		case IPPROTO_HOPOPTS:
3699		case IPPROTO_ROUTING: {
3700			struct ipv6_opt_hdr *hp;
3701
3702			err = skb_maybe_pull_tail(skb,
3703						  off +
3704						  sizeof(struct ipv6_opt_hdr),
3705						  MAX_IPV6_HDR_LEN);
3706			if (err < 0)
3707				goto out;
3708
3709			hp = OPT_HDR(struct ipv6_opt_hdr, skb, off);
3710			nexthdr = hp->nexthdr;
3711			off += ipv6_optlen(hp);
3712			break;
3713		}
3714		case IPPROTO_AH: {
3715			struct ip_auth_hdr *hp;
3716
3717			err = skb_maybe_pull_tail(skb,
3718						  off +
3719						  sizeof(struct ip_auth_hdr),
3720						  MAX_IPV6_HDR_LEN);
3721			if (err < 0)
3722				goto out;
3723
3724			hp = OPT_HDR(struct ip_auth_hdr, skb, off);
3725			nexthdr = hp->nexthdr;
3726			off += ipv6_authlen(hp);
3727			break;
3728		}
3729		case IPPROTO_FRAGMENT: {
3730			struct frag_hdr *hp;
3731
3732			err = skb_maybe_pull_tail(skb,
3733						  off +
3734						  sizeof(struct frag_hdr),
3735						  MAX_IPV6_HDR_LEN);
3736			if (err < 0)
3737				goto out;
3738
3739			hp = OPT_HDR(struct frag_hdr, skb, off);
3740
3741			if (hp->frag_off & htons(IP6_OFFSET | IP6_MF))
3742				fragment = true;
3743
3744			nexthdr = hp->nexthdr;
3745			off += sizeof(struct frag_hdr);
3746			break;
3747		}
3748		default:
3749			done = true;
3750			break;
3751		}
3752	}
3753
3754	err = -EPROTO;
3755
3756	if (!done || fragment)
3757		goto out;
3758
3759	csum = skb_checksum_setup_ip(skb, nexthdr, off);
3760	if (IS_ERR(csum))
3761		return PTR_ERR(csum);
3762
3763	if (recalculate)
3764		*csum = ~csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
3765					 &ipv6_hdr(skb)->daddr,
3766					 skb->len - off, nexthdr, 0);
3767	err = 0;
3768
3769out:
3770	return err;
3771}
3772
3773/**
3774 * skb_checksum_setup - set up partial checksum offset
3775 * @skb: the skb to set up
3776 * @recalculate: if true the pseudo-header checksum will be recalculated
3777 */
3778int skb_checksum_setup(struct sk_buff *skb, bool recalculate)
3779{
3780	int err;
3781
3782	switch (skb->protocol) {
3783	case htons(ETH_P_IP):
3784		err = skb_checksum_setup_ipv4(skb, recalculate);
3785		break;
3786
3787	case htons(ETH_P_IPV6):
3788		err = skb_checksum_setup_ipv6(skb, recalculate);
3789		break;
3790
3791	default:
3792		err = -EPROTO;
3793		break;
3794	}
3795
3796	return err;
3797}
3798EXPORT_SYMBOL(skb_checksum_setup);
3799
3800void __skb_warn_lro_forwarding(const struct sk_buff *skb)
3801{
3802	net_warn_ratelimited("%s: received packets cannot be forwarded while LRO is enabled\n",
3803			     skb->dev->name);
3804}
3805EXPORT_SYMBOL(__skb_warn_lro_forwarding);
3806
3807void kfree_skb_partial(struct sk_buff *skb, bool head_stolen)
3808{
3809	if (head_stolen) {
3810		skb_release_head_state(skb);
3811		kmem_cache_free(skbuff_head_cache, skb);
3812	} else {
3813		__kfree_skb(skb);
3814	}
3815}
3816EXPORT_SYMBOL(kfree_skb_partial);
3817
3818/**
3819 * skb_try_coalesce - try to merge skb to prior one
3820 * @to: prior buffer
3821 * @from: buffer to add
3822 * @fragstolen: pointer to boolean
3823 * @delta_truesize: how much more was allocated than was requested
3824 */
3825bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from,
3826		      bool *fragstolen, int *delta_truesize)
3827{
3828	int i, delta, len = from->len;
3829
3830	*fragstolen = false;
3831
3832	if (skb_cloned(to))
3833		return false;
3834
3835	if (len <= skb_tailroom(to)) {
3836		BUG_ON(skb_copy_bits(from, 0, skb_put(to, len), len));
3837		*delta_truesize = 0;
3838		return true;
3839	}
3840
3841	if (skb_has_frag_list(to) || skb_has_frag_list(from))
3842		return false;
3843
3844	if (skb_headlen(from) != 0) {
3845		struct page *page;
3846		unsigned int offset;
3847
3848		if (skb_shinfo(to)->nr_frags +
3849		    skb_shinfo(from)->nr_frags >= MAX_SKB_FRAGS)
3850			return false;
3851
3852		if (skb_head_is_locked(from))
3853			return false;
3854
3855		delta = from->truesize - SKB_DATA_ALIGN(sizeof(struct sk_buff));
3856
3857		page = virt_to_head_page(from->head);
3858		offset = from->data - (unsigned char *)page_address(page);
3859
3860		skb_fill_page_desc(to, skb_shinfo(to)->nr_frags,
3861				   page, offset, skb_headlen(from));
3862		*fragstolen = true;
3863	} else {
3864		if (skb_shinfo(to)->nr_frags +
3865		    skb_shinfo(from)->nr_frags > MAX_SKB_FRAGS)
3866			return false;
3867
3868		delta = from->truesize - SKB_TRUESIZE(skb_end_offset(from));
 
3869	}
3870
3871	WARN_ON_ONCE(delta < len);
3872
3873	memcpy(skb_shinfo(to)->frags + skb_shinfo(to)->nr_frags,
3874	       skb_shinfo(from)->frags,
3875	       skb_shinfo(from)->nr_frags * sizeof(skb_frag_t));
3876	skb_shinfo(to)->nr_frags += skb_shinfo(from)->nr_frags;
3877
3878	if (!skb_cloned(from))
3879		skb_shinfo(from)->nr_frags = 0;
3880
3881	/* if the skb is not cloned this does nothing
3882	 * since we set nr_frags to 0.
3883	 */
3884	for (i = 0; i < skb_shinfo(from)->nr_frags; i++)
3885		skb_frag_ref(from, i);
3886
3887	to->truesize += delta;
3888	to->len += len;
3889	to->data_len += len;
3890
3891	*delta_truesize = delta;
3892	return true;
3893}
3894EXPORT_SYMBOL(skb_try_coalesce);
3895
3896/**
3897 * skb_scrub_packet - scrub an skb
3898 *
3899 * @skb: buffer to clean
3900 * @xnet: packet is crossing netns
3901 *
3902 * skb_scrub_packet can be used after encapsulating or decapsulting a packet
3903 * into/from a tunnel. Some information have to be cleared during these
3904 * operations.
3905 * skb_scrub_packet can also be used to clean a skb before injecting it in
3906 * another namespace (@xnet == true). We have to clear all information in the
3907 * skb that could impact namespace isolation.
3908 */
3909void skb_scrub_packet(struct sk_buff *skb, bool xnet)
3910{
3911	if (xnet)
3912		skb_orphan(skb);
3913	skb->tstamp.tv64 = 0;
3914	skb->pkt_type = PACKET_HOST;
3915	skb->skb_iif = 0;
3916	skb->local_df = 0;
3917	skb_dst_drop(skb);
3918	skb->mark = 0;
3919	secpath_reset(skb);
3920	nf_reset(skb);
3921	nf_reset_trace(skb);
3922}
3923EXPORT_SYMBOL_GPL(skb_scrub_packet);
3924
3925/**
3926 * skb_gso_transport_seglen - Return length of individual segments of a gso packet
3927 *
3928 * @skb: GSO skb
3929 *
3930 * skb_gso_transport_seglen is used to determine the real size of the
3931 * individual segments, including Layer4 headers (TCP/UDP).
3932 *
3933 * The MAC/L2 or network (IP, IPv6) headers are not accounted for.
3934 */
3935unsigned int skb_gso_transport_seglen(const struct sk_buff *skb)
3936{
3937	const struct skb_shared_info *shinfo = skb_shinfo(skb);
3938
3939	if (likely(shinfo->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6)))
3940		return tcp_hdrlen(skb) + shinfo->gso_size;
3941
3942	/* UFO sets gso_size to the size of the fragmentation
3943	 * payload, i.e. the size of the L4 (UDP) header is already
3944	 * accounted for.
3945	 */
3946	return shinfo->gso_size;
3947}
3948EXPORT_SYMBOL_GPL(skb_gso_transport_seglen);