1/*
   2 * INET		An implementation of the TCP/IP protocol suite for the LINUX
   3 *		operating system.  INET is implemented using the  BSD Socket
   4 *		interface as the means of communication with the user level.
   5 *
   6 *		The Internet Protocol (IP) output module.
   7 *
   8 * Authors:	Ross Biro
   9 *		Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
  10 *		Donald Becker, <becker@super.org>
  11 *		Alan Cox, <Alan.Cox@linux.org>
  12 *		Richard Underwood
  13 *		Stefan Becker, <stefanb@yello.ping.de>
  14 *		Jorge Cwik, <jorge@laser.satlink.net>
  15 *		Arnt Gulbrandsen, <agulbra@nvg.unit.no>
  16 *		Hirokazu Takahashi, <taka@valinux.co.jp>
  17 *
  18 *	See ip_input.c for original log
  19 *
  20 *	Fixes:
  21 *		Alan Cox	:	Missing nonblock feature in ip_build_xmit.
  22 *		Mike Kilburn	:	htons() missing in ip_build_xmit.
  23 *		Bradford Johnson:	Fix faulty handling of some frames when
  24 *					no route is found.
  25 *		Alexander Demenshin:	Missing sk/skb free in ip_queue_xmit
  26 *					(in case if packet not accepted by
  27 *					output firewall rules)
  28 *		Mike McLagan	:	Routing by source
  29 *		Alexey Kuznetsov:	use new route cache
  30 *		Andi Kleen:		Fix broken PMTU recovery and remove
  31 *					some redundant tests.
  32 *	Vitaly E. Lavrov	:	Transparent proxy revived after year coma.
  33 *		Andi Kleen	: 	Replace ip_reply with ip_send_reply.
  34 *		Andi Kleen	:	Split fast and slow ip_build_xmit path
  35 *					for decreased register pressure on x86
  36 *					and more readibility.
  37 *		Marc Boucher	:	When call_out_firewall returns FW_QUEUE,
  38 *					silently drop skb instead of failing with -EPERM.
  39 *		Detlev Wengorz	:	Copy protocol for fragments.
  40 *		Hirokazu Takahashi:	HW checksumming for outgoing UDP
  41 *					datagrams.
  42 *		Hirokazu Takahashi:	sendfile() on UDP works now.
  43 */
  44
  45#include <asm/uaccess.h>
  46#include <linux/module.h>
  47#include <linux/types.h>
  48#include <linux/kernel.h>
  49#include <linux/mm.h>
  50#include <linux/string.h>
  51#include <linux/errno.h>
  52#include <linux/highmem.h>
  53#include <linux/slab.h>
  54
  55#include <linux/socket.h>
  56#include <linux/sockios.h>
  57#include <linux/in.h>
  58#include <linux/inet.h>
  59#include <linux/netdevice.h>
  60#include <linux/etherdevice.h>
  61#include <linux/proc_fs.h>
  62#include <linux/stat.h>
  63#include <linux/init.h>
  64
  65#include <net/snmp.h>
  66#include <net/ip.h>
  67#include <net/protocol.h>
  68#include <net/route.h>
  69#include <net/xfrm.h>
  70#include <linux/skbuff.h>
  71#include <net/sock.h>
  72#include <net/arp.h>
  73#include <net/icmp.h>
  74#include <net/checksum.h>
  75#include <net/inetpeer.h>
  76#include <linux/igmp.h>
  77#include <linux/netfilter_ipv4.h>
  78#include <linux/netfilter_bridge.h>
  79#include <linux/mroute.h>
  80#include <linux/netlink.h>
  81#include <linux/tcp.h>
  82
  83int sysctl_ip_default_ttl __read_mostly = IPDEFTTL;
  84EXPORT_SYMBOL(sysctl_ip_default_ttl);
  85
  86/* Generate a checksum for an outgoing IP datagram. */
  87void ip_send_check(struct iphdr *iph)
  88{
  89	iph->check = 0;
  90	iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
  91}
  92EXPORT_SYMBOL(ip_send_check);
  93
  94int __ip_local_out(struct sk_buff *skb)
  95{
  96	struct iphdr *iph = ip_hdr(skb);
  97
  98	iph->tot_len = htons(skb->len);
  99	ip_send_check(iph);
 100	return nf_hook(NFPROTO_IPV4, NF_INET_LOCAL_OUT, skb, NULL,
 101		       skb_dst(skb)->dev, dst_output);
 102}
 103
 104int ip_local_out_sk(struct sock *sk, struct sk_buff *skb)
 105{
 106	int err;
 107
 108	err = __ip_local_out(skb);
 109	if (likely(err == 1))
 110		err = dst_output_sk(sk, skb);
 111
 112	return err;
 113}
 114EXPORT_SYMBOL_GPL(ip_local_out_sk);
 
 
 
 
 
 
 
 
 
 
 
 
 
 115
 116static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst)
 117{
 118	int ttl = inet->uc_ttl;
 119
 120	if (ttl < 0)
 121		ttl = ip4_dst_hoplimit(dst);
 122	return ttl;
 123}
 124
 125/*
 126 *		Add an ip header to a skbuff and send it out.
 127 *
 128 */
 129int ip_build_and_send_pkt(struct sk_buff *skb, struct sock *sk,
 130			  __be32 saddr, __be32 daddr, struct ip_options_rcu *opt)
 131{
 132	struct inet_sock *inet = inet_sk(sk);
 133	struct rtable *rt = skb_rtable(skb);
 134	struct iphdr *iph;
 135
 136	/* Build the IP header. */
 137	skb_push(skb, sizeof(struct iphdr) + (opt ? opt->opt.optlen : 0));
 138	skb_reset_network_header(skb);
 139	iph = ip_hdr(skb);
 140	iph->version  = 4;
 141	iph->ihl      = 5;
 142	iph->tos      = inet->tos;
 143	if (ip_dont_fragment(sk, &rt->dst))
 144		iph->frag_off = htons(IP_DF);
 145	else
 146		iph->frag_off = 0;
 147	iph->ttl      = ip_select_ttl(inet, &rt->dst);
 148	iph->daddr    = (opt && opt->opt.srr ? opt->opt.faddr : daddr);
 149	iph->saddr    = saddr;
 150	iph->protocol = sk->sk_protocol;
 151	ip_select_ident(skb, &rt->dst, sk);
 152
 153	if (opt && opt->opt.optlen) {
 154		iph->ihl += opt->opt.optlen>>2;
 155		ip_options_build(skb, &opt->opt, daddr, rt, 0);
 156	}
 157
 158	skb->priority = sk->sk_priority;
 159	skb->mark = sk->sk_mark;
 160
 161	/* Send it out. */
 162	return ip_local_out(skb);
 163}
 164EXPORT_SYMBOL_GPL(ip_build_and_send_pkt);
 165
 166static inline int ip_finish_output2(struct sk_buff *skb)
 167{
 168	struct dst_entry *dst = skb_dst(skb);
 169	struct rtable *rt = (struct rtable *)dst;
 170	struct net_device *dev = dst->dev;
 171	unsigned int hh_len = LL_RESERVED_SPACE(dev);
 172	struct neighbour *neigh;
 173	u32 nexthop;
 174
 175	if (rt->rt_type == RTN_MULTICAST) {
 176		IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUTMCAST, skb->len);
 177	} else if (rt->rt_type == RTN_BROADCAST)
 178		IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUTBCAST, skb->len);
 179
 180	/* Be paranoid, rather than too clever. */
 181	if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) {
 182		struct sk_buff *skb2;
 183
 184		skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev));
 185		if (skb2 == NULL) {
 186			kfree_skb(skb);
 187			return -ENOMEM;
 188		}
 189		if (skb->sk)
 190			skb_set_owner_w(skb2, skb->sk);
 191		consume_skb(skb);
 192		skb = skb2;
 193	}
 194
 195	rcu_read_lock_bh();
 196	nexthop = (__force u32) rt_nexthop(rt, ip_hdr(skb)->daddr);
 197	neigh = __ipv4_neigh_lookup_noref(dev, nexthop);
 198	if (unlikely(!neigh))
 199		neigh = __neigh_create(&arp_tbl, &nexthop, dev, false);
 200	if (!IS_ERR(neigh)) {
 201		int res = dst_neigh_output(dst, neigh, skb);
 202
 203		rcu_read_unlock_bh();
 204		return res;
 205	}
 206	rcu_read_unlock_bh();
 207
 208	net_dbg_ratelimited("%s: No header cache and no neighbour!\n",
 209			    __func__);
 210	kfree_skb(skb);
 211	return -EINVAL;
 212}
 213
 214static int ip_finish_output_gso(struct sk_buff *skb)
 215{
 216	netdev_features_t features;
 217	struct sk_buff *segs;
 218	int ret = 0;
 219
 220	/* common case: locally created skb or seglen is <= mtu */
 221	if (((IPCB(skb)->flags & IPSKB_FORWARDED) == 0) ||
 222	      skb_gso_network_seglen(skb) <= ip_skb_dst_mtu(skb))
 223		return ip_finish_output2(skb);
 224
 225	/* Slowpath -  GSO segment length is exceeding the dst MTU.
 226	 *
 227	 * This can happen in two cases:
 228	 * 1) TCP GRO packet, DF bit not set
 229	 * 2) skb arrived via virtio-net, we thus get TSO/GSO skbs directly
 230	 * from host network stack.
 231	 */
 232	features = netif_skb_features(skb);
 233	segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK);
 234	if (IS_ERR(segs)) {
 235		kfree_skb(skb);
 236		return -ENOMEM;
 237	}
 238
 239	consume_skb(skb);
 240
 241	do {
 242		struct sk_buff *nskb = segs->next;
 243		int err;
 244
 245		segs->next = NULL;
 246		err = ip_fragment(segs, ip_finish_output2);
 247
 248		if (err && ret == 0)
 249			ret = err;
 250		segs = nskb;
 251	} while (segs);
 252
 253	return ret;
 254}
 255
 256static int ip_finish_output(struct sk_buff *skb)
 257{
 258#if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
 259	/* Policy lookup after SNAT yielded a new policy */
 260	if (skb_dst(skb)->xfrm != NULL) {
 261		IPCB(skb)->flags |= IPSKB_REROUTED;
 262		return dst_output(skb);
 263	}
 264#endif
 265	if (skb_is_gso(skb))
 266		return ip_finish_output_gso(skb);
 267
 268	if (skb->len > ip_skb_dst_mtu(skb))
 269		return ip_fragment(skb, ip_finish_output2);
 270
 271	return ip_finish_output2(skb);
 272}
 273
 274int ip_mc_output(struct sock *sk, struct sk_buff *skb)
 275{
 
 276	struct rtable *rt = skb_rtable(skb);
 277	struct net_device *dev = rt->dst.dev;
 278
 279	/*
 280	 *	If the indicated interface is up and running, send the packet.
 281	 */
 282	IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len);
 283
 284	skb->dev = dev;
 285	skb->protocol = htons(ETH_P_IP);
 286
 287	/*
 288	 *	Multicasts are looped back for other local users
 289	 */
 290
 291	if (rt->rt_flags&RTCF_MULTICAST) {
 292		if (sk_mc_loop(sk)
 293#ifdef CONFIG_IP_MROUTE
 294		/* Small optimization: do not loopback not local frames,
 295		   which returned after forwarding; they will be  dropped
 296		   by ip_mr_input in any case.
 297		   Note, that local frames are looped back to be delivered
 298		   to local recipients.
 299
 300		   This check is duplicated in ip_mr_input at the moment.
 301		 */
 302		    &&
 303		    ((rt->rt_flags & RTCF_LOCAL) ||
 304		     !(IPCB(skb)->flags & IPSKB_FORWARDED))
 305#endif
 306		   ) {
 307			struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
 308			if (newskb)
 309				NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
 310					newskb, NULL, newskb->dev,
 311					dev_loopback_xmit);
 312		}
 313
 314		/* Multicasts with ttl 0 must not go beyond the host */
 315
 316		if (ip_hdr(skb)->ttl == 0) {
 317			kfree_skb(skb);
 318			return 0;
 319		}
 320	}
 321
 322	if (rt->rt_flags&RTCF_BROADCAST) {
 323		struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
 324		if (newskb)
 325			NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, newskb,
 326				NULL, newskb->dev, dev_loopback_xmit);
 327	}
 328
 329	return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb, NULL,
 330			    skb->dev, ip_finish_output,
 331			    !(IPCB(skb)->flags & IPSKB_REROUTED));
 332}
 333
 334int ip_output(struct sock *sk, struct sk_buff *skb)
 335{
 336	struct net_device *dev = skb_dst(skb)->dev;
 337
 338	IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len);
 339
 340	skb->dev = dev;
 341	skb->protocol = htons(ETH_P_IP);
 342
 343	return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb, NULL, dev,
 344			    ip_finish_output,
 345			    !(IPCB(skb)->flags & IPSKB_REROUTED));
 346}
 347
 348/*
 349 * copy saddr and daddr, possibly using 64bit load/stores
 350 * Equivalent to :
 351 *   iph->saddr = fl4->saddr;
 352 *   iph->daddr = fl4->daddr;
 353 */
 354static void ip_copy_addrs(struct iphdr *iph, const struct flowi4 *fl4)
 355{
 356	BUILD_BUG_ON(offsetof(typeof(*fl4), daddr) !=
 357		     offsetof(typeof(*fl4), saddr) + sizeof(fl4->saddr));
 358	memcpy(&iph->saddr, &fl4->saddr,
 359	       sizeof(fl4->saddr) + sizeof(fl4->daddr));
 360}
 361
 362/* Note: skb->sk can be different from sk, in case of tunnels */
 363int ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl)
 364{
 
 365	struct inet_sock *inet = inet_sk(sk);
 366	struct ip_options_rcu *inet_opt;
 367	struct flowi4 *fl4;
 368	struct rtable *rt;
 369	struct iphdr *iph;
 370	int res;
 371
 372	/* Skip all of this if the packet is already routed,
 373	 * f.e. by something like SCTP.
 374	 */
 375	rcu_read_lock();
 376	inet_opt = rcu_dereference(inet->inet_opt);
 377	fl4 = &fl->u.ip4;
 378	rt = skb_rtable(skb);
 379	if (rt != NULL)
 380		goto packet_routed;
 381
 382	/* Make sure we can route this packet. */
 383	rt = (struct rtable *)__sk_dst_check(sk, 0);
 384	if (rt == NULL) {
 385		__be32 daddr;
 386
 387		/* Use correct destination address if we have options. */
 388		daddr = inet->inet_daddr;
 389		if (inet_opt && inet_opt->opt.srr)
 390			daddr = inet_opt->opt.faddr;
 391
 392		/* If this fails, retransmit mechanism of transport layer will
 393		 * keep trying until route appears or the connection times
 394		 * itself out.
 395		 */
 396		rt = ip_route_output_ports(sock_net(sk), fl4, sk,
 397					   daddr, inet->inet_saddr,
 398					   inet->inet_dport,
 399					   inet->inet_sport,
 400					   sk->sk_protocol,
 401					   RT_CONN_FLAGS(sk),
 402					   sk->sk_bound_dev_if);
 403		if (IS_ERR(rt))
 404			goto no_route;
 405		sk_setup_caps(sk, &rt->dst);
 406	}
 407	skb_dst_set_noref(skb, &rt->dst);
 408
 409packet_routed:
 410	if (inet_opt && inet_opt->opt.is_strictroute && rt->rt_uses_gateway)
 411		goto no_route;
 412
 413	/* OK, we know where to send it, allocate and build IP header. */
 414	skb_push(skb, sizeof(struct iphdr) + (inet_opt ? inet_opt->opt.optlen : 0));
 415	skb_reset_network_header(skb);
 416	iph = ip_hdr(skb);
 417	*((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (inet->tos & 0xff));
 418	if (ip_dont_fragment(sk, &rt->dst) && !skb->local_df)
 419		iph->frag_off = htons(IP_DF);
 420	else
 421		iph->frag_off = 0;
 422	iph->ttl      = ip_select_ttl(inet, &rt->dst);
 423	iph->protocol = sk->sk_protocol;
 424	ip_copy_addrs(iph, fl4);
 425
 426	/* Transport layer set skb->h.foo itself. */
 427
 428	if (inet_opt && inet_opt->opt.optlen) {
 429		iph->ihl += inet_opt->opt.optlen >> 2;
 430		ip_options_build(skb, &inet_opt->opt, inet->inet_daddr, rt, 0);
 431	}
 432
 433	ip_select_ident_more(skb, &rt->dst, sk,
 434			     (skb_shinfo(skb)->gso_segs ?: 1) - 1);
 435
 436	/* TODO : should we use skb->sk here instead of sk ? */
 437	skb->priority = sk->sk_priority;
 438	skb->mark = sk->sk_mark;
 439
 440	res = ip_local_out(skb);
 441	rcu_read_unlock();
 442	return res;
 443
 444no_route:
 445	rcu_read_unlock();
 446	IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
 447	kfree_skb(skb);
 448	return -EHOSTUNREACH;
 449}
 450EXPORT_SYMBOL(ip_queue_xmit);
 451
 452
 453static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from)
 454{
 455	to->pkt_type = from->pkt_type;
 456	to->priority = from->priority;
 457	to->protocol = from->protocol;
 458	skb_dst_drop(to);
 459	skb_dst_copy(to, from);
 460	to->dev = from->dev;
 461	to->mark = from->mark;
 462
 463	/* Copy the flags to each fragment. */
 464	IPCB(to)->flags = IPCB(from)->flags;
 465
 466#ifdef CONFIG_NET_SCHED
 467	to->tc_index = from->tc_index;
 468#endif
 469	nf_copy(to, from);
 
 
 
 
 470#if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
 471	to->ipvs_property = from->ipvs_property;
 472#endif
 473	skb_copy_secmark(to, from);
 474}
 475
 476/*
 477 *	This IP datagram is too large to be sent in one piece.  Break it up into
 478 *	smaller pieces (each of size equal to IP header plus
 479 *	a block of the data of the original IP data part) that will yet fit in a
 480 *	single device frame, and queue such a frame for sending.
 481 */
 482
 483int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *))
 484{
 485	struct iphdr *iph;
 486	int ptr;
 487	struct net_device *dev;
 488	struct sk_buff *skb2;
 489	unsigned int mtu, hlen, left, len, ll_rs;
 490	int offset;
 491	__be16 not_last_frag;
 492	struct rtable *rt = skb_rtable(skb);
 493	int err = 0;
 494
 495	dev = rt->dst.dev;
 496
 497	/*
 498	 *	Point into the IP datagram header.
 499	 */
 500
 501	iph = ip_hdr(skb);
 502
 503	mtu = ip_skb_dst_mtu(skb);
 504	if (unlikely(((iph->frag_off & htons(IP_DF)) && !skb->local_df) ||
 505		     (IPCB(skb)->frag_max_size &&
 506		      IPCB(skb)->frag_max_size > mtu))) {
 507		IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
 508		icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
 509			  htonl(mtu));
 510		kfree_skb(skb);
 511		return -EMSGSIZE;
 512	}
 513
 514	/*
 515	 *	Setup starting values.
 516	 */
 517
 518	hlen = iph->ihl * 4;
 519	mtu = mtu - hlen;	/* Size of data space */
 520#ifdef CONFIG_BRIDGE_NETFILTER
 521	if (skb->nf_bridge)
 522		mtu -= nf_bridge_mtu_reduction(skb);
 523#endif
 524	IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE;
 525
 526	/* When frag_list is given, use it. First, check its validity:
 527	 * some transformers could create wrong frag_list or break existing
 528	 * one, it is not prohibited. In this case fall back to copying.
 529	 *
 530	 * LATER: this step can be merged to real generation of fragments,
 531	 * we can switch to copy when see the first bad fragment.
 532	 */
 533	if (skb_has_frag_list(skb)) {
 534		struct sk_buff *frag, *frag2;
 535		int first_len = skb_pagelen(skb);
 536
 537		if (first_len - hlen > mtu ||
 538		    ((first_len - hlen) & 7) ||
 539		    ip_is_fragment(iph) ||
 540		    skb_cloned(skb))
 541			goto slow_path;
 542
 543		skb_walk_frags(skb, frag) {
 544			/* Correct geometry. */
 545			if (frag->len > mtu ||
 546			    ((frag->len & 7) && frag->next) ||
 547			    skb_headroom(frag) < hlen)
 548				goto slow_path_clean;
 549
 550			/* Partially cloned skb? */
 551			if (skb_shared(frag))
 552				goto slow_path_clean;
 553
 554			BUG_ON(frag->sk);
 555			if (skb->sk) {
 556				frag->sk = skb->sk;
 557				frag->destructor = sock_wfree;
 558			}
 559			skb->truesize -= frag->truesize;
 560		}
 561
 562		/* Everything is OK. Generate! */
 563
 564		err = 0;
 565		offset = 0;
 566		frag = skb_shinfo(skb)->frag_list;
 567		skb_frag_list_init(skb);
 568		skb->data_len = first_len - skb_headlen(skb);
 569		skb->len = first_len;
 570		iph->tot_len = htons(first_len);
 571		iph->frag_off = htons(IP_MF);
 572		ip_send_check(iph);
 573
 574		for (;;) {
 575			/* Prepare header of the next frame,
 576			 * before previous one went down. */
 577			if (frag) {
 578				frag->ip_summed = CHECKSUM_NONE;
 579				skb_reset_transport_header(frag);
 580				__skb_push(frag, hlen);
 581				skb_reset_network_header(frag);
 582				memcpy(skb_network_header(frag), iph, hlen);
 583				iph = ip_hdr(frag);
 584				iph->tot_len = htons(frag->len);
 585				ip_copy_metadata(frag, skb);
 586				if (offset == 0)
 587					ip_options_fragment(frag);
 588				offset += skb->len - hlen;
 589				iph->frag_off = htons(offset>>3);
 590				if (frag->next != NULL)
 591					iph->frag_off |= htons(IP_MF);
 592				/* Ready, complete checksum */
 593				ip_send_check(iph);
 594			}
 595
 596			err = output(skb);
 597
 598			if (!err)
 599				IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES);
 600			if (err || !frag)
 601				break;
 602
 603			skb = frag;
 604			frag = skb->next;
 605			skb->next = NULL;
 606		}
 607
 608		if (err == 0) {
 609			IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS);
 610			return 0;
 611		}
 612
 613		while (frag) {
 614			skb = frag->next;
 615			kfree_skb(frag);
 616			frag = skb;
 617		}
 618		IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
 619		return err;
 620
 621slow_path_clean:
 622		skb_walk_frags(skb, frag2) {
 623			if (frag2 == frag)
 624				break;
 625			frag2->sk = NULL;
 626			frag2->destructor = NULL;
 627			skb->truesize += frag2->truesize;
 628		}
 629	}
 630
 631slow_path:
 632	/* for offloaded checksums cleanup checksum before fragmentation */
 633	if ((skb->ip_summed == CHECKSUM_PARTIAL) && skb_checksum_help(skb))
 634		goto fail;
 635	iph = ip_hdr(skb);
 636
 637	left = skb->len - hlen;		/* Space per frame */
 638	ptr = hlen;		/* Where to start from */
 639
 640	/* for bridged IP traffic encapsulated inside f.e. a vlan header,
 641	 * we need to make room for the encapsulating header
 642	 */
 643	ll_rs = LL_RESERVED_SPACE_EXTRA(rt->dst.dev, nf_bridge_pad(skb));
 644
 645	/*
 646	 *	Fragment the datagram.
 647	 */
 648
 649	offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3;
 650	not_last_frag = iph->frag_off & htons(IP_MF);
 651
 652	/*
 653	 *	Keep copying data until we run out.
 654	 */
 655
 656	while (left > 0) {
 657		len = left;
 658		/* IF: it doesn't fit, use 'mtu' - the data space left */
 659		if (len > mtu)
 660			len = mtu;
 661		/* IF: we are not sending up to and including the packet end
 662		   then align the next start on an eight byte boundary */
 663		if (len < left)	{
 664			len &= ~7;
 665		}
 666		/*
 667		 *	Allocate buffer.
 668		 */
 669
 670		if ((skb2 = alloc_skb(len+hlen+ll_rs, GFP_ATOMIC)) == NULL) {
 671			NETDEBUG(KERN_INFO "IP: frag: no memory for new fragment!\n");
 672			err = -ENOMEM;
 673			goto fail;
 674		}
 675
 676		/*
 677		 *	Set up data on packet
 678		 */
 679
 680		ip_copy_metadata(skb2, skb);
 681		skb_reserve(skb2, ll_rs);
 682		skb_put(skb2, len + hlen);
 683		skb_reset_network_header(skb2);
 684		skb2->transport_header = skb2->network_header + hlen;
 685
 686		/*
 687		 *	Charge the memory for the fragment to any owner
 688		 *	it might possess
 689		 */
 690
 691		if (skb->sk)
 692			skb_set_owner_w(skb2, skb->sk);
 693
 694		/*
 695		 *	Copy the packet header into the new buffer.
 696		 */
 697
 698		skb_copy_from_linear_data(skb, skb_network_header(skb2), hlen);
 699
 700		/*
 701		 *	Copy a block of the IP datagram.
 702		 */
 703		if (skb_copy_bits(skb, ptr, skb_transport_header(skb2), len))
 704			BUG();
 705		left -= len;
 706
 707		/*
 708		 *	Fill in the new header fields.
 709		 */
 710		iph = ip_hdr(skb2);
 711		iph->frag_off = htons((offset >> 3));
 712
 713		/* ANK: dirty, but effective trick. Upgrade options only if
 714		 * the segment to be fragmented was THE FIRST (otherwise,
 715		 * options are already fixed) and make it ONCE
 716		 * on the initial skb, so that all the following fragments
 717		 * will inherit fixed options.
 718		 */
 719		if (offset == 0)
 720			ip_options_fragment(skb);
 721
 722		/*
 723		 *	Added AC : If we are fragmenting a fragment that's not the
 724		 *		   last fragment then keep MF on each bit
 725		 */
 726		if (left > 0 || not_last_frag)
 727			iph->frag_off |= htons(IP_MF);
 728		ptr += len;
 729		offset += len;
 730
 731		/*
 732		 *	Put this fragment into the sending queue.
 733		 */
 734		iph->tot_len = htons(len + hlen);
 735
 736		ip_send_check(iph);
 737
 738		err = output(skb2);
 739		if (err)
 740			goto fail;
 741
 742		IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES);
 743	}
 744	consume_skb(skb);
 745	IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS);
 746	return err;
 747
 748fail:
 749	kfree_skb(skb);
 750	IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
 751	return err;
 752}
 753EXPORT_SYMBOL(ip_fragment);
 754
 755int
 756ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
 757{
 758	struct iovec *iov = from;
 759
 760	if (skb->ip_summed == CHECKSUM_PARTIAL) {
 761		if (memcpy_fromiovecend(to, iov, offset, len) < 0)
 762			return -EFAULT;
 763	} else {
 764		__wsum csum = 0;
 765		if (csum_partial_copy_fromiovecend(to, iov, offset, len, &csum) < 0)
 766			return -EFAULT;
 767		skb->csum = csum_block_add(skb->csum, csum, odd);
 768	}
 769	return 0;
 770}
 771EXPORT_SYMBOL(ip_generic_getfrag);
 772
 773static inline __wsum
 774csum_page(struct page *page, int offset, int copy)
 775{
 776	char *kaddr;
 777	__wsum csum;
 778	kaddr = kmap(page);
 779	csum = csum_partial(kaddr + offset, copy, 0);
 780	kunmap(page);
 781	return csum;
 782}
 783
 784static inline int ip_ufo_append_data(struct sock *sk,
 785			struct sk_buff_head *queue,
 786			int getfrag(void *from, char *to, int offset, int len,
 787			       int odd, struct sk_buff *skb),
 788			void *from, int length, int hh_len, int fragheaderlen,
 789			int transhdrlen, int maxfraglen, unsigned int flags)
 790{
 791	struct sk_buff *skb;
 792	int err;
 793
 794	/* There is support for UDP fragmentation offload by network
 795	 * device, so create one single skb packet containing complete
 796	 * udp datagram
 797	 */
 798	if ((skb = skb_peek_tail(queue)) == NULL) {
 799		skb = sock_alloc_send_skb(sk,
 800			hh_len + fragheaderlen + transhdrlen + 20,
 801			(flags & MSG_DONTWAIT), &err);
 802
 803		if (skb == NULL)
 804			return err;
 805
 806		/* reserve space for Hardware header */
 807		skb_reserve(skb, hh_len);
 808
 809		/* create space for UDP/IP header */
 810		skb_put(skb, fragheaderlen + transhdrlen);
 811
 812		/* initialize network header pointer */
 813		skb_reset_network_header(skb);
 814
 815		/* initialize protocol header pointer */
 816		skb->transport_header = skb->network_header + fragheaderlen;
 817
 
 818		skb->csum = 0;
 819
 820
 
 
 821		__skb_queue_tail(queue, skb);
 822	} else if (skb_is_gso(skb)) {
 823		goto append;
 824	}
 825
 826	skb->ip_summed = CHECKSUM_PARTIAL;
 827	/* specify the length of each IP datagram fragment */
 828	skb_shinfo(skb)->gso_size = maxfraglen - fragheaderlen;
 829	skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
 830
 831append:
 832	return skb_append_datato_frags(sk, skb, getfrag, from,
 833				       (length - transhdrlen));
 834}
 835
 836static int __ip_append_data(struct sock *sk,
 837			    struct flowi4 *fl4,
 838			    struct sk_buff_head *queue,
 839			    struct inet_cork *cork,
 840			    struct page_frag *pfrag,
 841			    int getfrag(void *from, char *to, int offset,
 842					int len, int odd, struct sk_buff *skb),
 843			    void *from, int length, int transhdrlen,
 844			    unsigned int flags)
 845{
 846	struct inet_sock *inet = inet_sk(sk);
 847	struct sk_buff *skb;
 848
 849	struct ip_options *opt = cork->opt;
 850	int hh_len;
 851	int exthdrlen;
 852	int mtu;
 853	int copy;
 854	int err;
 855	int offset = 0;
 856	unsigned int maxfraglen, fragheaderlen, maxnonfragsize;
 857	int csummode = CHECKSUM_NONE;
 858	struct rtable *rt = (struct rtable *)cork->dst;
 859
 860	skb = skb_peek_tail(queue);
 861
 862	exthdrlen = !skb ? rt->dst.header_len : 0;
 863	mtu = cork->fragsize;
 864
 865	hh_len = LL_RESERVED_SPACE(rt->dst.dev);
 866
 867	fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
 868	maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
 869	maxnonfragsize = ip_sk_local_df(sk) ? 0xFFFF : mtu;
 870
 871	if (cork->length + length > maxnonfragsize - fragheaderlen) {
 872		ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
 873			       mtu - (opt ? opt->optlen : 0));
 874		return -EMSGSIZE;
 875	}
 876
 877	/*
 878	 * transhdrlen > 0 means that this is the first fragment and we wish
 879	 * it won't be fragmented in the future.
 880	 */
 881	if (transhdrlen &&
 882	    length + fragheaderlen <= mtu &&
 883	    rt->dst.dev->features & NETIF_F_V4_CSUM &&
 884	    !exthdrlen)
 885		csummode = CHECKSUM_PARTIAL;
 886
 887	cork->length += length;
 888	if (((length > mtu) || (skb && skb_is_gso(skb))) &&
 889	    (sk->sk_protocol == IPPROTO_UDP) &&
 890	    (rt->dst.dev->features & NETIF_F_UFO) && !rt->dst.header_len) {
 891		err = ip_ufo_append_data(sk, queue, getfrag, from, length,
 892					 hh_len, fragheaderlen, transhdrlen,
 893					 maxfraglen, flags);
 894		if (err)
 895			goto error;
 896		return 0;
 897	}
 898
 899	/* So, what's going on in the loop below?
 900	 *
 901	 * We use calculated fragment length to generate chained skb,
 902	 * each of segments is IP fragment ready for sending to network after
 903	 * adding appropriate IP header.
 904	 */
 905
 906	if (!skb)
 907		goto alloc_new_skb;
 908
 909	while (length > 0) {
 910		/* Check if the remaining data fits into current packet. */
 911		copy = mtu - skb->len;
 912		if (copy < length)
 913			copy = maxfraglen - skb->len;
 914		if (copy <= 0) {
 915			char *data;
 916			unsigned int datalen;
 917			unsigned int fraglen;
 918			unsigned int fraggap;
 919			unsigned int alloclen;
 920			struct sk_buff *skb_prev;
 921alloc_new_skb:
 922			skb_prev = skb;
 923			if (skb_prev)
 924				fraggap = skb_prev->len - maxfraglen;
 925			else
 926				fraggap = 0;
 927
 928			/*
 929			 * If remaining data exceeds the mtu,
 930			 * we know we need more fragment(s).
 931			 */
 932			datalen = length + fraggap;
 933			if (datalen > mtu - fragheaderlen)
 934				datalen = maxfraglen - fragheaderlen;
 935			fraglen = datalen + fragheaderlen;
 936
 937			if ((flags & MSG_MORE) &&
 938			    !(rt->dst.dev->features&NETIF_F_SG))
 939				alloclen = mtu;
 940			else
 941				alloclen = fraglen;
 942
 943			alloclen += exthdrlen;
 944
 945			/* The last fragment gets additional space at tail.
 946			 * Note, with MSG_MORE we overallocate on fragments,
 947			 * because we have no idea what fragment will be
 948			 * the last.
 949			 */
 950			if (datalen == length + fraggap)
 951				alloclen += rt->dst.trailer_len;
 952
 953			if (transhdrlen) {
 954				skb = sock_alloc_send_skb(sk,
 955						alloclen + hh_len + 15,
 956						(flags & MSG_DONTWAIT), &err);
 957			} else {
 958				skb = NULL;
 959				if (atomic_read(&sk->sk_wmem_alloc) <=
 960				    2 * sk->sk_sndbuf)
 961					skb = sock_wmalloc(sk,
 962							   alloclen + hh_len + 15, 1,
 963							   sk->sk_allocation);
 964				if (unlikely(skb == NULL))
 965					err = -ENOBUFS;
 966				else
 967					/* only the initial fragment is
 968					   time stamped */
 969					cork->tx_flags = 0;
 970			}
 971			if (skb == NULL)
 972				goto error;
 973
 974			/*
 975			 *	Fill in the control structures
 976			 */
 977			skb->ip_summed = csummode;
 978			skb->csum = 0;
 979			skb_reserve(skb, hh_len);
 980			skb_shinfo(skb)->tx_flags = cork->tx_flags;
 981
 982			/*
 983			 *	Find where to start putting bytes.
 984			 */
 985			data = skb_put(skb, fraglen + exthdrlen);
 986			skb_set_network_header(skb, exthdrlen);
 987			skb->transport_header = (skb->network_header +
 988						 fragheaderlen);
 989			data += fragheaderlen + exthdrlen;
 990
 991			if (fraggap) {
 992				skb->csum = skb_copy_and_csum_bits(
 993					skb_prev, maxfraglen,
 994					data + transhdrlen, fraggap, 0);
 995				skb_prev->csum = csum_sub(skb_prev->csum,
 996							  skb->csum);
 997				data += fraggap;
 998				pskb_trim_unique(skb_prev, maxfraglen);
 999			}
1000
1001			copy = datalen - transhdrlen - fraggap;
1002			if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) {
1003				err = -EFAULT;
1004				kfree_skb(skb);
1005				goto error;
1006			}
1007
1008			offset += copy;
1009			length -= datalen - fraggap;
1010			transhdrlen = 0;
1011			exthdrlen = 0;
1012			csummode = CHECKSUM_NONE;
1013
1014			/*
1015			 * Put the packet on the pending queue.
1016			 */
1017			__skb_queue_tail(queue, skb);
1018			continue;
1019		}
1020
1021		if (copy > length)
1022			copy = length;
1023
1024		if (!(rt->dst.dev->features&NETIF_F_SG)) {
1025			unsigned int off;
1026
1027			off = skb->len;
1028			if (getfrag(from, skb_put(skb, copy),
1029					offset, copy, off, skb) < 0) {
1030				__skb_trim(skb, off);
1031				err = -EFAULT;
1032				goto error;
1033			}
1034		} else {
1035			int i = skb_shinfo(skb)->nr_frags;
1036
1037			err = -ENOMEM;
1038			if (!sk_page_frag_refill(sk, pfrag))
1039				goto error;
1040
1041			if (!skb_can_coalesce(skb, i, pfrag->page,
1042					      pfrag->offset)) {
1043				err = -EMSGSIZE;
1044				if (i == MAX_SKB_FRAGS)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1045					goto error;
 
 
 
1046
1047				__skb_fill_page_desc(skb, i, pfrag->page,
1048						     pfrag->offset, 0);
1049				skb_shinfo(skb)->nr_frags = ++i;
1050				get_page(pfrag->page);
 
1051			}
1052			copy = min_t(int, copy, pfrag->size - pfrag->offset);
1053			if (getfrag(from,
1054				    page_address(pfrag->page) + pfrag->offset,
1055				    offset, copy, skb->len, skb) < 0)
1056				goto error_efault;
1057
1058			pfrag->offset += copy;
1059			skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
1060			skb->len += copy;
1061			skb->data_len += copy;
1062			skb->truesize += copy;
1063			atomic_add(copy, &sk->sk_wmem_alloc);
1064		}
1065		offset += copy;
1066		length -= copy;
1067	}
1068
1069	return 0;
1070
1071error_efault:
1072	err = -EFAULT;
1073error:
1074	cork->length -= length;
1075	IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1076	return err;
1077}
1078
1079static int ip_setup_cork(struct sock *sk, struct inet_cork *cork,
1080			 struct ipcm_cookie *ipc, struct rtable **rtp)
1081{
 
1082	struct ip_options_rcu *opt;
1083	struct rtable *rt;
1084
1085	/*
1086	 * setup for corking.
1087	 */
1088	opt = ipc->opt;
1089	if (opt) {
1090		if (cork->opt == NULL) {
1091			cork->opt = kmalloc(sizeof(struct ip_options) + 40,
1092					    sk->sk_allocation);
1093			if (unlikely(cork->opt == NULL))
1094				return -ENOBUFS;
1095		}
1096		memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen);
1097		cork->flags |= IPCORK_OPT;
1098		cork->addr = ipc->addr;
1099	}
1100	rt = *rtp;
1101	if (unlikely(!rt))
1102		return -EFAULT;
1103	/*
1104	 * We steal reference to this route, caller should not release it
1105	 */
1106	*rtp = NULL;
1107	cork->fragsize = ip_sk_use_pmtu(sk) ?
1108			 dst_mtu(&rt->dst) : rt->dst.dev->mtu;
1109	cork->dst = &rt->dst;
1110	cork->length = 0;
1111	cork->ttl = ipc->ttl;
1112	cork->tos = ipc->tos;
1113	cork->priority = ipc->priority;
1114	cork->tx_flags = ipc->tx_flags;
 
 
1115
1116	return 0;
1117}
1118
1119/*
1120 *	ip_append_data() and ip_append_page() can make one large IP datagram
1121 *	from many pieces of data. Each pieces will be holded on the socket
1122 *	until ip_push_pending_frames() is called. Each piece can be a page
1123 *	or non-page data.
1124 *
1125 *	Not only UDP, other transport protocols - e.g. raw sockets - can use
1126 *	this interface potentially.
1127 *
1128 *	LATER: length must be adjusted by pad at tail, when it is required.
1129 */
1130int ip_append_data(struct sock *sk, struct flowi4 *fl4,
1131		   int getfrag(void *from, char *to, int offset, int len,
1132			       int odd, struct sk_buff *skb),
1133		   void *from, int length, int transhdrlen,
1134		   struct ipcm_cookie *ipc, struct rtable **rtp,
1135		   unsigned int flags)
1136{
1137	struct inet_sock *inet = inet_sk(sk);
1138	int err;
1139
1140	if (flags&MSG_PROBE)
1141		return 0;
1142
1143	if (skb_queue_empty(&sk->sk_write_queue)) {
1144		err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp);
1145		if (err)
1146			return err;
1147	} else {
1148		transhdrlen = 0;
1149	}
1150
1151	return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base,
1152				sk_page_frag(sk), getfrag,
1153				from, length, transhdrlen, flags);
1154}
1155
1156ssize_t	ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page,
1157		       int offset, size_t size, int flags)
1158{
1159	struct inet_sock *inet = inet_sk(sk);
1160	struct sk_buff *skb;
1161	struct rtable *rt;
1162	struct ip_options *opt = NULL;
1163	struct inet_cork *cork;
1164	int hh_len;
1165	int mtu;
1166	int len;
1167	int err;
1168	unsigned int maxfraglen, fragheaderlen, fraggap, maxnonfragsize;
1169
1170	if (inet->hdrincl)
1171		return -EPERM;
1172
1173	if (flags&MSG_PROBE)
1174		return 0;
1175
1176	if (skb_queue_empty(&sk->sk_write_queue))
1177		return -EINVAL;
1178
1179	cork = &inet->cork.base;
1180	rt = (struct rtable *)cork->dst;
1181	if (cork->flags & IPCORK_OPT)
1182		opt = cork->opt;
1183
1184	if (!(rt->dst.dev->features&NETIF_F_SG))
1185		return -EOPNOTSUPP;
1186
1187	hh_len = LL_RESERVED_SPACE(rt->dst.dev);
1188	mtu = cork->fragsize;
1189
1190	fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
1191	maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
1192	maxnonfragsize = ip_sk_local_df(sk) ? 0xFFFF : mtu;
1193
1194	if (cork->length + size > maxnonfragsize - fragheaderlen) {
1195		ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
1196			       mtu - (opt ? opt->optlen : 0));
1197		return -EMSGSIZE;
1198	}
1199
1200	if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL)
1201		return -EINVAL;
1202
1203	cork->length += size;
1204	if ((size + skb->len > mtu) &&
1205	    (sk->sk_protocol == IPPROTO_UDP) &&
1206	    (rt->dst.dev->features & NETIF_F_UFO)) {
1207		skb_shinfo(skb)->gso_size = mtu - fragheaderlen;
1208		skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
1209	}
1210
1211
1212	while (size > 0) {
1213		int i;
1214
1215		if (skb_is_gso(skb))
1216			len = size;
1217		else {
1218
1219			/* Check if the remaining data fits into current packet. */
1220			len = mtu - skb->len;
1221			if (len < size)
1222				len = maxfraglen - skb->len;
1223		}
1224		if (len <= 0) {
1225			struct sk_buff *skb_prev;
1226			int alloclen;
1227
1228			skb_prev = skb;
1229			fraggap = skb_prev->len - maxfraglen;
1230
1231			alloclen = fragheaderlen + hh_len + fraggap + 15;
1232			skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation);
1233			if (unlikely(!skb)) {
1234				err = -ENOBUFS;
1235				goto error;
1236			}
1237
1238			/*
1239			 *	Fill in the control structures
1240			 */
1241			skb->ip_summed = CHECKSUM_NONE;
1242			skb->csum = 0;
1243			skb_reserve(skb, hh_len);
1244
1245			/*
1246			 *	Find where to start putting bytes.
1247			 */
1248			skb_put(skb, fragheaderlen + fraggap);
1249			skb_reset_network_header(skb);
1250			skb->transport_header = (skb->network_header +
1251						 fragheaderlen);
1252			if (fraggap) {
1253				skb->csum = skb_copy_and_csum_bits(skb_prev,
1254								   maxfraglen,
1255						    skb_transport_header(skb),
1256								   fraggap, 0);
1257				skb_prev->csum = csum_sub(skb_prev->csum,
1258							  skb->csum);
1259				pskb_trim_unique(skb_prev, maxfraglen);
1260			}
1261
1262			/*
1263			 * Put the packet on the pending queue.
1264			 */
1265			__skb_queue_tail(&sk->sk_write_queue, skb);
1266			continue;
1267		}
1268
1269		i = skb_shinfo(skb)->nr_frags;
1270		if (len > size)
1271			len = size;
1272		if (skb_can_coalesce(skb, i, page, offset)) {
1273			skb_frag_size_add(&skb_shinfo(skb)->frags[i-1], len);
1274		} else if (i < MAX_SKB_FRAGS) {
1275			get_page(page);
1276			skb_fill_page_desc(skb, i, page, offset, len);
1277		} else {
1278			err = -EMSGSIZE;
1279			goto error;
1280		}
1281
1282		if (skb->ip_summed == CHECKSUM_NONE) {
1283			__wsum csum;
1284			csum = csum_page(page, offset, len);
1285			skb->csum = csum_block_add(skb->csum, csum, skb->len);
1286		}
1287
1288		skb->len += len;
1289		skb->data_len += len;
1290		skb->truesize += len;
1291		atomic_add(len, &sk->sk_wmem_alloc);
1292		offset += len;
1293		size -= len;
1294	}
1295	return 0;
1296
1297error:
1298	cork->length -= size;
1299	IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1300	return err;
1301}
1302
1303static void ip_cork_release(struct inet_cork *cork)
1304{
1305	cork->flags &= ~IPCORK_OPT;
1306	kfree(cork->opt);
1307	cork->opt = NULL;
1308	dst_release(cork->dst);
1309	cork->dst = NULL;
1310}
1311
1312/*
1313 *	Combined all pending IP fragments on the socket as one IP datagram
1314 *	and push them out.
1315 */
1316struct sk_buff *__ip_make_skb(struct sock *sk,
1317			      struct flowi4 *fl4,
1318			      struct sk_buff_head *queue,
1319			      struct inet_cork *cork)
1320{
1321	struct sk_buff *skb, *tmp_skb;
1322	struct sk_buff **tail_skb;
1323	struct inet_sock *inet = inet_sk(sk);
1324	struct net *net = sock_net(sk);
1325	struct ip_options *opt = NULL;
1326	struct rtable *rt = (struct rtable *)cork->dst;
1327	struct iphdr *iph;
1328	__be16 df = 0;
1329	__u8 ttl;
1330
1331	if ((skb = __skb_dequeue(queue)) == NULL)
1332		goto out;
1333	tail_skb = &(skb_shinfo(skb)->frag_list);
1334
1335	/* move skb->data to ip header from ext header */
1336	if (skb->data < skb_network_header(skb))
1337		__skb_pull(skb, skb_network_offset(skb));
1338	while ((tmp_skb = __skb_dequeue(queue)) != NULL) {
1339		__skb_pull(tmp_skb, skb_network_header_len(skb));
1340		*tail_skb = tmp_skb;
1341		tail_skb = &(tmp_skb->next);
1342		skb->len += tmp_skb->len;
1343		skb->data_len += tmp_skb->len;
1344		skb->truesize += tmp_skb->truesize;
1345		tmp_skb->destructor = NULL;
1346		tmp_skb->sk = NULL;
1347	}
1348
1349	/* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow
1350	 * to fragment the frame generated here. No matter, what transforms
1351	 * how transforms change size of the packet, it will come out.
1352	 */
1353	skb->local_df = ip_sk_local_df(sk);
 
1354
1355	/* DF bit is set when we want to see DF on outgoing frames.
1356	 * If local_df is set too, we still allow to fragment this frame
1357	 * locally. */
1358	if (inet->pmtudisc == IP_PMTUDISC_DO ||
1359	    inet->pmtudisc == IP_PMTUDISC_PROBE ||
1360	    (skb->len <= dst_mtu(&rt->dst) &&
1361	     ip_dont_fragment(sk, &rt->dst)))
1362		df = htons(IP_DF);
1363
1364	if (cork->flags & IPCORK_OPT)
1365		opt = cork->opt;
1366
1367	if (cork->ttl != 0)
1368		ttl = cork->ttl;
1369	else if (rt->rt_type == RTN_MULTICAST)
1370		ttl = inet->mc_ttl;
1371	else
1372		ttl = ip_select_ttl(inet, &rt->dst);
1373
1374	iph = ip_hdr(skb);
1375	iph->version = 4;
1376	iph->ihl = 5;
1377	iph->tos = (cork->tos != -1) ? cork->tos : inet->tos;
1378	iph->frag_off = df;
 
1379	iph->ttl = ttl;
1380	iph->protocol = sk->sk_protocol;
1381	ip_copy_addrs(iph, fl4);
1382	ip_select_ident(skb, &rt->dst, sk);
1383
1384	if (opt) {
1385		iph->ihl += opt->optlen>>2;
1386		ip_options_build(skb, opt, cork->addr, rt, 0);
1387	}
1388
1389	skb->priority = (cork->tos != -1) ? cork->priority: sk->sk_priority;
1390	skb->mark = sk->sk_mark;
1391	/*
1392	 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec
1393	 * on dst refcount
1394	 */
1395	cork->dst = NULL;
1396	skb_dst_set(skb, &rt->dst);
1397
1398	if (iph->protocol == IPPROTO_ICMP)
1399		icmp_out_count(net, ((struct icmphdr *)
1400			skb_transport_header(skb))->type);
1401
1402	ip_cork_release(cork);
1403out:
1404	return skb;
1405}
1406
1407int ip_send_skb(struct net *net, struct sk_buff *skb)
1408{
 
1409	int err;
1410
1411	err = ip_local_out(skb);
1412	if (err) {
1413		if (err > 0)
1414			err = net_xmit_errno(err);
1415		if (err)
1416			IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS);
1417	}
1418
1419	return err;
1420}
1421
1422int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4)
1423{
1424	struct sk_buff *skb;
1425
1426	skb = ip_finish_skb(sk, fl4);
1427	if (!skb)
1428		return 0;
1429
1430	/* Netfilter gets whole the not fragmented skb. */
1431	return ip_send_skb(sock_net(sk), skb);
1432}
1433
1434/*
1435 *	Throw away all pending data on the socket.
1436 */
1437static void __ip_flush_pending_frames(struct sock *sk,
1438				      struct sk_buff_head *queue,
1439				      struct inet_cork *cork)
1440{
1441	struct sk_buff *skb;
1442
1443	while ((skb = __skb_dequeue_tail(queue)) != NULL)
1444		kfree_skb(skb);
1445
1446	ip_cork_release(cork);
1447}
1448
1449void ip_flush_pending_frames(struct sock *sk)
1450{
1451	__ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork.base);
1452}
1453
1454struct sk_buff *ip_make_skb(struct sock *sk,
1455			    struct flowi4 *fl4,
1456			    int getfrag(void *from, char *to, int offset,
1457					int len, int odd, struct sk_buff *skb),
1458			    void *from, int length, int transhdrlen,
1459			    struct ipcm_cookie *ipc, struct rtable **rtp,
1460			    unsigned int flags)
1461{
1462	struct inet_cork cork;
1463	struct sk_buff_head queue;
1464	int err;
1465
1466	if (flags & MSG_PROBE)
1467		return NULL;
1468
1469	__skb_queue_head_init(&queue);
1470
1471	cork.flags = 0;
1472	cork.addr = 0;
1473	cork.opt = NULL;
1474	err = ip_setup_cork(sk, &cork, ipc, rtp);
1475	if (err)
1476		return ERR_PTR(err);
1477
1478	err = __ip_append_data(sk, fl4, &queue, &cork,
1479			       &current->task_frag, getfrag,
1480			       from, length, transhdrlen, flags);
1481	if (err) {
1482		__ip_flush_pending_frames(sk, &queue, &cork);
1483		return ERR_PTR(err);
1484	}
1485
1486	return __ip_make_skb(sk, fl4, &queue, &cork);
1487}
1488
1489/*
1490 *	Fetch data from kernel space and fill in checksum if needed.
1491 */
1492static int ip_reply_glue_bits(void *dptr, char *to, int offset,
1493			      int len, int odd, struct sk_buff *skb)
1494{
1495	__wsum csum;
1496
1497	csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0);
1498	skb->csum = csum_block_add(skb->csum, csum, odd);
1499	return 0;
1500}
1501
1502/*
1503 *	Generic function to send a packet as reply to another packet.
1504 *	Used to send some TCP resets/acks so far.
1505 *
1506 *	Use a fake percpu inet socket to avoid false sharing and contention.
 
1507 */
1508static DEFINE_PER_CPU(struct inet_sock, unicast_sock) = {
1509	.sk = {
1510		.__sk_common = {
1511			.skc_refcnt = ATOMIC_INIT(1),
1512		},
1513		.sk_wmem_alloc	= ATOMIC_INIT(1),
1514		.sk_allocation	= GFP_ATOMIC,
1515		.sk_flags	= (1UL << SOCK_USE_WRITE_QUEUE),
1516	},
1517	.pmtudisc	= IP_PMTUDISC_WANT,
1518	.uc_ttl		= -1,
1519};
1520
1521void ip_send_unicast_reply(struct net *net, struct sk_buff *skb, __be32 daddr,
1522			   __be32 saddr, const struct ip_reply_arg *arg,
1523			   unsigned int len)
1524{
 
1525	struct ip_options_data replyopts;
1526	struct ipcm_cookie ipc;
1527	struct flowi4 fl4;
1528	struct rtable *rt = skb_rtable(skb);
1529	struct sk_buff *nskb;
1530	struct sock *sk;
1531	struct inet_sock *inet;
1532
1533	if (ip_options_echo(&replyopts.opt.opt, skb))
1534		return;
1535
1536	ipc.addr = daddr;
1537	ipc.opt = NULL;
1538	ipc.tx_flags = 0;
1539	ipc.ttl = 0;
1540	ipc.tos = -1;
1541
1542	if (replyopts.opt.opt.optlen) {
1543		ipc.opt = &replyopts.opt;
1544
1545		if (replyopts.opt.opt.srr)
1546			daddr = replyopts.opt.opt.faddr;
1547	}
1548
1549	flowi4_init_output(&fl4, arg->bound_dev_if, 0,
1550			   RT_TOS(arg->tos),
1551			   RT_SCOPE_UNIVERSE, ip_hdr(skb)->protocol,
1552			   ip_reply_arg_flowi_flags(arg),
1553			   daddr, saddr,
1554			   tcp_hdr(skb)->source, tcp_hdr(skb)->dest);
1555	security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
1556	rt = ip_route_output_key(net, &fl4);
1557	if (IS_ERR(rt))
1558		return;
1559
1560	inet = &get_cpu_var(unicast_sock);
1561
 
 
 
 
 
1562	inet->tos = arg->tos;
1563	sk = &inet->sk;
1564	sk->sk_priority = skb->priority;
1565	sk->sk_protocol = ip_hdr(skb)->protocol;
1566	sk->sk_bound_dev_if = arg->bound_dev_if;
1567	sock_net_set(sk, net);
1568	__skb_queue_head_init(&sk->sk_write_queue);
1569	sk->sk_sndbuf = sysctl_wmem_default;
1570	ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base, len, 0,
1571		       &ipc, &rt, MSG_DONTWAIT);
1572	nskb = skb_peek(&sk->sk_write_queue);
1573	if (nskb) {
1574		if (arg->csumoffset >= 0)
1575			*((__sum16 *)skb_transport_header(nskb) +
1576			  arg->csumoffset) = csum_fold(csum_add(nskb->csum,
1577								arg->csum));
1578		nskb->ip_summed = CHECKSUM_NONE;
1579		skb_orphan(nskb);
1580		skb_set_queue_mapping(nskb, skb_get_queue_mapping(skb));
1581		ip_push_pending_frames(sk, &fl4);
1582	}
1583
1584	put_cpu_var(unicast_sock);
1585
1586	ip_rt_put(rt);
1587}
1588
1589void __init ip_init(void)
1590{
1591	ip_rt_init();
1592	inet_initpeers();
1593
1594#if defined(CONFIG_IP_MULTICAST)
1595	igmp_mc_init();
1596#endif
1597}