1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * INET		An implementation of the TCP/IP protocol suite for the LINUX
   4 *		operating system.  INET is implemented using the  BSD Socket
   5 *		interface as the means of communication with the user level.
   6 *
   7 *		The Internet Protocol (IP) output module.
   8 *
   9 * Authors:	Ross Biro
  10 *		Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
  11 *		Donald Becker, <becker@super.org>
  12 *		Alan Cox, <Alan.Cox@linux.org>
  13 *		Richard Underwood
  14 *		Stefan Becker, <stefanb@yello.ping.de>
  15 *		Jorge Cwik, <jorge@laser.satlink.net>
  16 *		Arnt Gulbrandsen, <agulbra@nvg.unit.no>
  17 *		Hirokazu Takahashi, <taka@valinux.co.jp>
  18 *
  19 *	See ip_input.c for original log
  20 *
  21 *	Fixes:
  22 *		Alan Cox	:	Missing nonblock feature in ip_build_xmit.
  23 *		Mike Kilburn	:	htons() missing in ip_build_xmit.
  24 *		Bradford Johnson:	Fix faulty handling of some frames when
  25 *					no route is found.
  26 *		Alexander Demenshin:	Missing sk/skb free in ip_queue_xmit
  27 *					(in case if packet not accepted by
  28 *					output firewall rules)
  29 *		Mike McLagan	:	Routing by source
  30 *		Alexey Kuznetsov:	use new route cache
  31 *		Andi Kleen:		Fix broken PMTU recovery and remove
  32 *					some redundant tests.
  33 *	Vitaly E. Lavrov	:	Transparent proxy revived after year coma.
  34 *		Andi Kleen	: 	Replace ip_reply with ip_send_reply.
  35 *		Andi Kleen	:	Split fast and slow ip_build_xmit path
  36 *					for decreased register pressure on x86
  37 *					and more readibility.
  38 *		Marc Boucher	:	When call_out_firewall returns FW_QUEUE,
  39 *					silently drop skb instead of failing with -EPERM.
  40 *		Detlev Wengorz	:	Copy protocol for fragments.
  41 *		Hirokazu Takahashi:	HW checksumming for outgoing UDP
  42 *					datagrams.
  43 *		Hirokazu Takahashi:	sendfile() on UDP works now.
  44 */
  45
  46#include <linux/uaccess.h>
  47#include <linux/module.h>
  48#include <linux/types.h>
  49#include <linux/kernel.h>
  50#include <linux/mm.h>
  51#include <linux/string.h>
  52#include <linux/errno.h>
  53#include <linux/highmem.h>
  54#include <linux/slab.h>
  55
  56#include <linux/socket.h>
  57#include <linux/sockios.h>
  58#include <linux/in.h>
  59#include <linux/inet.h>
  60#include <linux/netdevice.h>
  61#include <linux/etherdevice.h>
  62#include <linux/proc_fs.h>
  63#include <linux/stat.h>
  64#include <linux/init.h>
  65
  66#include <net/snmp.h>
  67#include <net/ip.h>
  68#include <net/protocol.h>
  69#include <net/route.h>
  70#include <net/xfrm.h>
  71#include <linux/skbuff.h>
  72#include <net/sock.h>
  73#include <net/arp.h>
  74#include <net/icmp.h>
  75#include <net/checksum.h>
 
  76#include <net/inetpeer.h>
 
  77#include <net/lwtunnel.h>
  78#include <linux/bpf-cgroup.h>
  79#include <linux/igmp.h>
  80#include <linux/netfilter_ipv4.h>
  81#include <linux/netfilter_bridge.h>
  82#include <linux/netlink.h>
  83#include <linux/tcp.h>
  84
  85static int
  86ip_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
  87	    unsigned int mtu,
  88	    int (*output)(struct net *, struct sock *, struct sk_buff *));
  89
  90/* Generate a checksum for an outgoing IP datagram. */
  91void ip_send_check(struct iphdr *iph)
  92{
  93	iph->check = 0;
  94	iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
  95}
  96EXPORT_SYMBOL(ip_send_check);
  97
  98int __ip_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
  99{
 100	struct iphdr *iph = ip_hdr(skb);
 101
 102	iph->tot_len = htons(skb->len);
 
 
 103	ip_send_check(iph);
 104
 105	/* if egress device is enslaved to an L3 master device pass the
 106	 * skb to its handler for processing
 107	 */
 108	skb = l3mdev_ip_out(sk, skb);
 109	if (unlikely(!skb))
 110		return 0;
 111
 112	skb->protocol = htons(ETH_P_IP);
 113
 114	return nf_hook(NFPROTO_IPV4, NF_INET_LOCAL_OUT,
 115		       net, sk, skb, NULL, skb_dst(skb)->dev,
 116		       dst_output);
 117}
 118
 119int ip_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
 120{
 121	int err;
 122
 123	err = __ip_local_out(net, sk, skb);
 124	if (likely(err == 1))
 125		err = dst_output(net, sk, skb);
 126
 127	return err;
 128}
 129EXPORT_SYMBOL_GPL(ip_local_out);
 130
 131static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst)
 
 132{
 133	int ttl = inet->uc_ttl;
 134
 135	if (ttl < 0)
 136		ttl = ip4_dst_hoplimit(dst);
 137	return ttl;
 138}
 139
 140/*
 141 *		Add an ip header to a skbuff and send it out.
 142 *
 143 */
 144int ip_build_and_send_pkt(struct sk_buff *skb, const struct sock *sk,
 145			  __be32 saddr, __be32 daddr, struct ip_options_rcu *opt)
 
 146{
 147	struct inet_sock *inet = inet_sk(sk);
 148	struct rtable *rt = skb_rtable(skb);
 149	struct net *net = sock_net(sk);
 150	struct iphdr *iph;
 151
 152	/* Build the IP header. */
 153	skb_push(skb, sizeof(struct iphdr) + (opt ? opt->opt.optlen : 0));
 154	skb_reset_network_header(skb);
 155	iph = ip_hdr(skb);
 156	iph->version  = 4;
 157	iph->ihl      = 5;
 158	iph->tos      = inet->tos;
 159	iph->ttl      = ip_select_ttl(inet, &rt->dst);
 160	iph->daddr    = (opt && opt->opt.srr ? opt->opt.faddr : daddr);
 161	iph->saddr    = saddr;
 162	iph->protocol = sk->sk_protocol;
 163	if (ip_dont_fragment(sk, &rt->dst)) {
 
 164		iph->frag_off = htons(IP_DF);
 165		iph->id = 0;
 166	} else {
 167		iph->frag_off = 0;
 168		__ip_select_ident(net, iph, 1);
 
 
 
 
 
 
 169	}
 170
 171	if (opt && opt->opt.optlen) {
 172		iph->ihl += opt->opt.optlen>>2;
 173		ip_options_build(skb, &opt->opt, daddr, rt, 0);
 174	}
 175
 176	skb->priority = sk->sk_priority;
 177	if (!skb->mark)
 178		skb->mark = sk->sk_mark;
 179
 180	/* Send it out. */
 181	return ip_local_out(net, skb->sk, skb);
 182}
 183EXPORT_SYMBOL_GPL(ip_build_and_send_pkt);
 184
 185static int ip_finish_output2(struct net *net, struct sock *sk, struct sk_buff *skb)
 186{
 187	struct dst_entry *dst = skb_dst(skb);
 188	struct rtable *rt = (struct rtable *)dst;
 189	struct net_device *dev = dst->dev;
 190	unsigned int hh_len = LL_RESERVED_SPACE(dev);
 191	struct neighbour *neigh;
 192	bool is_v6gw = false;
 193
 194	if (rt->rt_type == RTN_MULTICAST) {
 195		IP_UPD_PO_STATS(net, IPSTATS_MIB_OUTMCAST, skb->len);
 196	} else if (rt->rt_type == RTN_BROADCAST)
 197		IP_UPD_PO_STATS(net, IPSTATS_MIB_OUTBCAST, skb->len);
 198
 199	/* Be paranoid, rather than too clever. */
 200	if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) {
 201		struct sk_buff *skb2;
 202
 203		skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev));
 204		if (!skb2) {
 205			kfree_skb(skb);
 206			return -ENOMEM;
 207		}
 208		if (skb->sk)
 209			skb_set_owner_w(skb2, skb->sk);
 210		consume_skb(skb);
 211		skb = skb2;
 212	}
 213
 214	if (lwtunnel_xmit_redirect(dst->lwtstate)) {
 215		int res = lwtunnel_xmit(skb);
 216
 217		if (res < 0 || res == LWTUNNEL_XMIT_DONE)
 218			return res;
 219	}
 220
 221	rcu_read_lock_bh();
 222	neigh = ip_neigh_for_gw(rt, skb, &is_v6gw);
 223	if (!IS_ERR(neigh)) {
 224		int res;
 225
 226		sock_confirm_neigh(skb, neigh);
 227		/* if crossing protocols, can not use the cached header */
 228		res = neigh_output(neigh, skb, is_v6gw);
 229		rcu_read_unlock_bh();
 230		return res;
 231	}
 232	rcu_read_unlock_bh();
 233
 234	net_dbg_ratelimited("%s: No header cache and no neighbour!\n",
 235			    __func__);
 236	kfree_skb(skb);
 237	return -EINVAL;
 238}
 239
 240static int ip_finish_output_gso(struct net *net, struct sock *sk,
 241				struct sk_buff *skb, unsigned int mtu)
 242{
 
 243	netdev_features_t features;
 244	struct sk_buff *segs;
 245	int ret = 0;
 246
 247	/* common case: seglen is <= mtu
 248	 */
 249	if (skb_gso_validate_network_len(skb, mtu))
 250		return ip_finish_output2(net, sk, skb);
 251
 252	/* Slowpath -  GSO segment length exceeds the egress MTU.
 253	 *
 254	 * This can happen in several cases:
 255	 *  - Forwarding of a TCP GRO skb, when DF flag is not set.
 256	 *  - Forwarding of an skb that arrived on a virtualization interface
 257	 *    (virtio-net/vhost/tap) with TSO/GSO size set by other network
 258	 *    stack.
 259	 *  - Local GSO skb transmitted on an NETIF_F_TSO tunnel stacked over an
 260	 *    interface with a smaller MTU.
 261	 *  - Arriving GRO skb (or GSO skb in a virtualized environment) that is
 262	 *    bridged to a NETIF_F_TSO tunnel stacked over an interface with an
 263	 *    insufficent MTU.
 264	 */
 265	features = netif_skb_features(skb);
 266	BUILD_BUG_ON(sizeof(*IPCB(skb)) > SKB_SGO_CB_OFFSET);
 267	segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK);
 268	if (IS_ERR_OR_NULL(segs)) {
 269		kfree_skb(skb);
 270		return -ENOMEM;
 271	}
 272
 273	consume_skb(skb);
 274
 275	do {
 276		struct sk_buff *nskb = segs->next;
 277		int err;
 278
 279		skb_mark_not_on_list(segs);
 280		err = ip_fragment(net, sk, segs, mtu, ip_finish_output2);
 281
 282		if (err && ret == 0)
 283			ret = err;
 284		segs = nskb;
 285	} while (segs);
 286
 287	return ret;
 288}
 289
 290static int __ip_finish_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 291{
 292	unsigned int mtu;
 293
 294#if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
 295	/* Policy lookup after SNAT yielded a new policy */
 296	if (skb_dst(skb)->xfrm) {
 297		IPCB(skb)->flags |= IPSKB_REROUTED;
 298		return dst_output(net, sk, skb);
 299	}
 300#endif
 301	mtu = ip_skb_dst_mtu(sk, skb);
 302	if (skb_is_gso(skb))
 303		return ip_finish_output_gso(net, sk, skb, mtu);
 304
 305	if (skb->len > mtu || (IPCB(skb)->flags & IPSKB_FRAG_PMTU))
 306		return ip_fragment(net, sk, skb, mtu, ip_finish_output2);
 307
 308	return ip_finish_output2(net, sk, skb);
 309}
 310
 311static int ip_finish_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 312{
 313	int ret;
 314
 315	ret = BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb);
 316	switch (ret) {
 317	case NET_XMIT_SUCCESS:
 318		return __ip_finish_output(net, sk, skb);
 319	case NET_XMIT_CN:
 320		return __ip_finish_output(net, sk, skb) ? : ret;
 321	default:
 322		kfree_skb(skb);
 323		return ret;
 324	}
 325}
 326
 327static int ip_mc_finish_output(struct net *net, struct sock *sk,
 328			       struct sk_buff *skb)
 329{
 330	struct rtable *new_rt;
 331	bool do_cn = false;
 332	int ret, err;
 333
 334	ret = BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb);
 335	switch (ret) {
 336	case NET_XMIT_CN:
 337		do_cn = true;
 338		/* fall through */
 339	case NET_XMIT_SUCCESS:
 340		break;
 341	default:
 342		kfree_skb(skb);
 343		return ret;
 344	}
 345
 346	/* Reset rt_iif so that inet_iif() will return skb->skb_iif. Setting
 347	 * this to non-zero causes ipi_ifindex in in_pktinfo to be overwritten,
 348	 * see ipv4_pktinfo_prepare().
 349	 */
 350	new_rt = rt_dst_clone(net->loopback_dev, skb_rtable(skb));
 351	if (new_rt) {
 352		new_rt->rt_iif = 0;
 353		skb_dst_drop(skb);
 354		skb_dst_set(skb, &new_rt->dst);
 355	}
 356
 357	err = dev_loopback_xmit(net, sk, skb);
 358	return (do_cn && err) ? ret : err;
 359}
 360
 361int ip_mc_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 362{
 363	struct rtable *rt = skb_rtable(skb);
 364	struct net_device *dev = rt->dst.dev;
 365
 366	/*
 367	 *	If the indicated interface is up and running, send the packet.
 368	 */
 369	IP_UPD_PO_STATS(net, IPSTATS_MIB_OUT, skb->len);
 370
 371	skb->dev = dev;
 372	skb->protocol = htons(ETH_P_IP);
 373
 374	/*
 375	 *	Multicasts are looped back for other local users
 376	 */
 377
 378	if (rt->rt_flags&RTCF_MULTICAST) {
 379		if (sk_mc_loop(sk)
 380#ifdef CONFIG_IP_MROUTE
 381		/* Small optimization: do not loopback not local frames,
 382		   which returned after forwarding; they will be  dropped
 383		   by ip_mr_input in any case.
 384		   Note, that local frames are looped back to be delivered
 385		   to local recipients.
 386
 387		   This check is duplicated in ip_mr_input at the moment.
 388		 */
 389		    &&
 390		    ((rt->rt_flags & RTCF_LOCAL) ||
 391		     !(IPCB(skb)->flags & IPSKB_FORWARDED))
 392#endif
 393		   ) {
 394			struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
 395			if (newskb)
 396				NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
 397					net, sk, newskb, NULL, newskb->dev,
 398					ip_mc_finish_output);
 399		}
 400
 401		/* Multicasts with ttl 0 must not go beyond the host */
 402
 403		if (ip_hdr(skb)->ttl == 0) {
 404			kfree_skb(skb);
 405			return 0;
 406		}
 407	}
 408
 409	if (rt->rt_flags&RTCF_BROADCAST) {
 410		struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
 411		if (newskb)
 412			NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
 413				net, sk, newskb, NULL, newskb->dev,
 414				ip_mc_finish_output);
 415	}
 416
 417	return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
 418			    net, sk, skb, NULL, skb->dev,
 419			    ip_finish_output,
 420			    !(IPCB(skb)->flags & IPSKB_REROUTED));
 421}
 422
 423int ip_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 424{
 425	struct net_device *dev = skb_dst(skb)->dev;
 426
 427	IP_UPD_PO_STATS(net, IPSTATS_MIB_OUT, skb->len);
 428
 429	skb->dev = dev;
 430	skb->protocol = htons(ETH_P_IP);
 431
 432	return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
 433			    net, sk, skb, NULL, dev,
 434			    ip_finish_output,
 435			    !(IPCB(skb)->flags & IPSKB_REROUTED));
 436}
 
 437
 438/*
 439 * copy saddr and daddr, possibly using 64bit load/stores
 440 * Equivalent to :
 441 *   iph->saddr = fl4->saddr;
 442 *   iph->daddr = fl4->daddr;
 443 */
 444static void ip_copy_addrs(struct iphdr *iph, const struct flowi4 *fl4)
 445{
 446	BUILD_BUG_ON(offsetof(typeof(*fl4), daddr) !=
 447		     offsetof(typeof(*fl4), saddr) + sizeof(fl4->saddr));
 448	memcpy(&iph->saddr, &fl4->saddr,
 449	       sizeof(fl4->saddr) + sizeof(fl4->daddr));
 
 450}
 451
 452/* Note: skb->sk can be different from sk, in case of tunnels */
 453int __ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl,
 454		    __u8 tos)
 455{
 456	struct inet_sock *inet = inet_sk(sk);
 457	struct net *net = sock_net(sk);
 458	struct ip_options_rcu *inet_opt;
 459	struct flowi4 *fl4;
 460	struct rtable *rt;
 461	struct iphdr *iph;
 462	int res;
 463
 464	/* Skip all of this if the packet is already routed,
 465	 * f.e. by something like SCTP.
 466	 */
 467	rcu_read_lock();
 468	inet_opt = rcu_dereference(inet->inet_opt);
 469	fl4 = &fl->u.ip4;
 470	rt = skb_rtable(skb);
 471	if (rt)
 472		goto packet_routed;
 473
 474	/* Make sure we can route this packet. */
 475	rt = (struct rtable *)__sk_dst_check(sk, 0);
 476	if (!rt) {
 477		__be32 daddr;
 478
 479		/* Use correct destination address if we have options. */
 480		daddr = inet->inet_daddr;
 481		if (inet_opt && inet_opt->opt.srr)
 482			daddr = inet_opt->opt.faddr;
 483
 484		/* If this fails, retransmit mechanism of transport layer will
 485		 * keep trying until route appears or the connection times
 486		 * itself out.
 487		 */
 488		rt = ip_route_output_ports(net, fl4, sk,
 489					   daddr, inet->inet_saddr,
 490					   inet->inet_dport,
 491					   inet->inet_sport,
 492					   sk->sk_protocol,
 493					   RT_CONN_FLAGS_TOS(sk, tos),
 494					   sk->sk_bound_dev_if);
 495		if (IS_ERR(rt))
 496			goto no_route;
 497		sk_setup_caps(sk, &rt->dst);
 498	}
 499	skb_dst_set_noref(skb, &rt->dst);
 500
 501packet_routed:
 502	if (inet_opt && inet_opt->opt.is_strictroute && rt->rt_uses_gateway)
 503		goto no_route;
 504
 505	/* OK, we know where to send it, allocate and build IP header. */
 506	skb_push(skb, sizeof(struct iphdr) + (inet_opt ? inet_opt->opt.optlen : 0));
 507	skb_reset_network_header(skb);
 508	iph = ip_hdr(skb);
 509	*((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (tos & 0xff));
 510	if (ip_dont_fragment(sk, &rt->dst) && !skb->ignore_df)
 511		iph->frag_off = htons(IP_DF);
 512	else
 513		iph->frag_off = 0;
 514	iph->ttl      = ip_select_ttl(inet, &rt->dst);
 515	iph->protocol = sk->sk_protocol;
 516	ip_copy_addrs(iph, fl4);
 517
 518	/* Transport layer set skb->h.foo itself. */
 519
 520	if (inet_opt && inet_opt->opt.optlen) {
 521		iph->ihl += inet_opt->opt.optlen >> 2;
 522		ip_options_build(skb, &inet_opt->opt, inet->inet_daddr, rt, 0);
 523	}
 524
 525	ip_select_ident_segs(net, skb, sk,
 526			     skb_shinfo(skb)->gso_segs ?: 1);
 527
 528	/* TODO : should we use skb->sk here instead of sk ? */
 529	skb->priority = sk->sk_priority;
 530	skb->mark = sk->sk_mark;
 531
 532	res = ip_local_out(net, sk, skb);
 533	rcu_read_unlock();
 534	return res;
 535
 536no_route:
 537	rcu_read_unlock();
 538	IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
 539	kfree_skb(skb);
 540	return -EHOSTUNREACH;
 541}
 542EXPORT_SYMBOL(__ip_queue_xmit);
 543
 
 
 
 
 
 
 544static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from)
 545{
 546	to->pkt_type = from->pkt_type;
 547	to->priority = from->priority;
 548	to->protocol = from->protocol;
 549	to->skb_iif = from->skb_iif;
 550	skb_dst_drop(to);
 551	skb_dst_copy(to, from);
 552	to->dev = from->dev;
 553	to->mark = from->mark;
 554
 555	skb_copy_hash(to, from);
 556
 557#ifdef CONFIG_NET_SCHED
 558	to->tc_index = from->tc_index;
 559#endif
 560	nf_copy(to, from);
 561	skb_ext_copy(to, from);
 562#if IS_ENABLED(CONFIG_IP_VS)
 563	to->ipvs_property = from->ipvs_property;
 564#endif
 565	skb_copy_secmark(to, from);
 566}
 567
 568static int ip_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
 569		       unsigned int mtu,
 570		       int (*output)(struct net *, struct sock *, struct sk_buff *))
 571{
 572	struct iphdr *iph = ip_hdr(skb);
 573
 574	if ((iph->frag_off & htons(IP_DF)) == 0)
 575		return ip_do_fragment(net, sk, skb, output);
 576
 577	if (unlikely(!skb->ignore_df ||
 578		     (IPCB(skb)->frag_max_size &&
 579		      IPCB(skb)->frag_max_size > mtu))) {
 580		IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
 581		icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
 582			  htonl(mtu));
 583		kfree_skb(skb);
 584		return -EMSGSIZE;
 585	}
 586
 587	return ip_do_fragment(net, sk, skb, output);
 588}
 589
 590void ip_fraglist_init(struct sk_buff *skb, struct iphdr *iph,
 591		      unsigned int hlen, struct ip_fraglist_iter *iter)
 592{
 593	unsigned int first_len = skb_pagelen(skb);
 594
 595	iter->frag = skb_shinfo(skb)->frag_list;
 596	skb_frag_list_init(skb);
 597
 598	iter->offset = 0;
 599	iter->iph = iph;
 600	iter->hlen = hlen;
 601
 602	skb->data_len = first_len - skb_headlen(skb);
 603	skb->len = first_len;
 604	iph->tot_len = htons(first_len);
 605	iph->frag_off = htons(IP_MF);
 606	ip_send_check(iph);
 607}
 608EXPORT_SYMBOL(ip_fraglist_init);
 609
 610static void ip_fraglist_ipcb_prepare(struct sk_buff *skb,
 611				     struct ip_fraglist_iter *iter)
 612{
 613	struct sk_buff *to = iter->frag;
 614
 615	/* Copy the flags to each fragment. */
 616	IPCB(to)->flags = IPCB(skb)->flags;
 617
 618	if (iter->offset == 0)
 619		ip_options_fragment(to);
 620}
 621
 622void ip_fraglist_prepare(struct sk_buff *skb, struct ip_fraglist_iter *iter)
 623{
 624	unsigned int hlen = iter->hlen;
 625	struct iphdr *iph = iter->iph;
 626	struct sk_buff *frag;
 627
 628	frag = iter->frag;
 629	frag->ip_summed = CHECKSUM_NONE;
 630	skb_reset_transport_header(frag);
 631	__skb_push(frag, hlen);
 632	skb_reset_network_header(frag);
 633	memcpy(skb_network_header(frag), iph, hlen);
 634	iter->iph = ip_hdr(frag);
 635	iph = iter->iph;
 636	iph->tot_len = htons(frag->len);
 637	ip_copy_metadata(frag, skb);
 638	iter->offset += skb->len - hlen;
 639	iph->frag_off = htons(iter->offset >> 3);
 640	if (frag->next)
 641		iph->frag_off |= htons(IP_MF);
 642	/* Ready, complete checksum */
 643	ip_send_check(iph);
 644}
 645EXPORT_SYMBOL(ip_fraglist_prepare);
 646
 647void ip_frag_init(struct sk_buff *skb, unsigned int hlen,
 648		  unsigned int ll_rs, unsigned int mtu, bool DF,
 649		  struct ip_frag_state *state)
 650{
 651	struct iphdr *iph = ip_hdr(skb);
 652
 653	state->DF = DF;
 654	state->hlen = hlen;
 655	state->ll_rs = ll_rs;
 656	state->mtu = mtu;
 657
 658	state->left = skb->len - hlen;	/* Space per frame */
 659	state->ptr = hlen;		/* Where to start from */
 660
 661	state->offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3;
 662	state->not_last_frag = iph->frag_off & htons(IP_MF);
 663}
 664EXPORT_SYMBOL(ip_frag_init);
 665
 666static void ip_frag_ipcb(struct sk_buff *from, struct sk_buff *to,
 667			 bool first_frag, struct ip_frag_state *state)
 668{
 669	/* Copy the flags to each fragment. */
 670	IPCB(to)->flags = IPCB(from)->flags;
 671
 672	/* ANK: dirty, but effective trick. Upgrade options only if
 673	 * the segment to be fragmented was THE FIRST (otherwise,
 674	 * options are already fixed) and make it ONCE
 675	 * on the initial skb, so that all the following fragments
 676	 * will inherit fixed options.
 677	 */
 678	if (first_frag)
 679		ip_options_fragment(from);
 680}
 681
 682struct sk_buff *ip_frag_next(struct sk_buff *skb, struct ip_frag_state *state)
 683{
 684	unsigned int len = state->left;
 685	struct sk_buff *skb2;
 686	struct iphdr *iph;
 687
 688	len = state->left;
 689	/* IF: it doesn't fit, use 'mtu' - the data space left */
 690	if (len > state->mtu)
 691		len = state->mtu;
 692	/* IF: we are not sending up to and including the packet end
 693	   then align the next start on an eight byte boundary */
 694	if (len < state->left)	{
 695		len &= ~7;
 696	}
 697
 698	/* Allocate buffer */
 699	skb2 = alloc_skb(len + state->hlen + state->ll_rs, GFP_ATOMIC);
 700	if (!skb2)
 701		return ERR_PTR(-ENOMEM);
 702
 703	/*
 704	 *	Set up data on packet
 705	 */
 706
 707	ip_copy_metadata(skb2, skb);
 708	skb_reserve(skb2, state->ll_rs);
 709	skb_put(skb2, len + state->hlen);
 710	skb_reset_network_header(skb2);
 711	skb2->transport_header = skb2->network_header + state->hlen;
 712
 713	/*
 714	 *	Charge the memory for the fragment to any owner
 715	 *	it might possess
 716	 */
 717
 718	if (skb->sk)
 719		skb_set_owner_w(skb2, skb->sk);
 720
 721	/*
 722	 *	Copy the packet header into the new buffer.
 723	 */
 724
 725	skb_copy_from_linear_data(skb, skb_network_header(skb2), state->hlen);
 726
 727	/*
 728	 *	Copy a block of the IP datagram.
 729	 */
 730	if (skb_copy_bits(skb, state->ptr, skb_transport_header(skb2), len))
 731		BUG();
 732	state->left -= len;
 733
 734	/*
 735	 *	Fill in the new header fields.
 736	 */
 737	iph = ip_hdr(skb2);
 738	iph->frag_off = htons((state->offset >> 3));
 739	if (state->DF)
 740		iph->frag_off |= htons(IP_DF);
 741
 742	/*
 743	 *	Added AC : If we are fragmenting a fragment that's not the
 744	 *		   last fragment then keep MF on each bit
 745	 */
 746	if (state->left > 0 || state->not_last_frag)
 747		iph->frag_off |= htons(IP_MF);
 748	state->ptr += len;
 749	state->offset += len;
 750
 751	iph->tot_len = htons(len + state->hlen);
 752
 753	ip_send_check(iph);
 754
 755	return skb2;
 756}
 757EXPORT_SYMBOL(ip_frag_next);
 758
 759/*
 760 *	This IP datagram is too large to be sent in one piece.  Break it up into
 761 *	smaller pieces (each of size equal to IP header plus
 762 *	a block of the data of the original IP data part) that will yet fit in a
 763 *	single device frame, and queue such a frame for sending.
 764 */
 765
 766int ip_do_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
 767		   int (*output)(struct net *, struct sock *, struct sk_buff *))
 768{
 769	struct iphdr *iph;
 770	struct sk_buff *skb2;
 
 771	struct rtable *rt = skb_rtable(skb);
 772	unsigned int mtu, hlen, ll_rs;
 773	struct ip_fraglist_iter iter;
 774	ktime_t tstamp = skb->tstamp;
 775	struct ip_frag_state state;
 776	int err = 0;
 777
 778	/* for offloaded checksums cleanup checksum before fragmentation */
 779	if (skb->ip_summed == CHECKSUM_PARTIAL &&
 780	    (err = skb_checksum_help(skb)))
 781		goto fail;
 782
 783	/*
 784	 *	Point into the IP datagram header.
 785	 */
 786
 787	iph = ip_hdr(skb);
 788
 789	mtu = ip_skb_dst_mtu(sk, skb);
 790	if (IPCB(skb)->frag_max_size && IPCB(skb)->frag_max_size < mtu)
 791		mtu = IPCB(skb)->frag_max_size;
 792
 793	/*
 794	 *	Setup starting values.
 795	 */
 796
 797	hlen = iph->ihl * 4;
 798	mtu = mtu - hlen;	/* Size of data space */
 799	IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE;
 800	ll_rs = LL_RESERVED_SPACE(rt->dst.dev);
 801
 802	/* When frag_list is given, use it. First, check its validity:
 803	 * some transformers could create wrong frag_list or break existing
 804	 * one, it is not prohibited. In this case fall back to copying.
 805	 *
 806	 * LATER: this step can be merged to real generation of fragments,
 807	 * we can switch to copy when see the first bad fragment.
 808	 */
 809	if (skb_has_frag_list(skb)) {
 810		struct sk_buff *frag, *frag2;
 811		unsigned int first_len = skb_pagelen(skb);
 812
 813		if (first_len - hlen > mtu ||
 814		    ((first_len - hlen) & 7) ||
 815		    ip_is_fragment(iph) ||
 816		    skb_cloned(skb) ||
 817		    skb_headroom(skb) < ll_rs)
 818			goto slow_path;
 819
 820		skb_walk_frags(skb, frag) {
 821			/* Correct geometry. */
 822			if (frag->len > mtu ||
 823			    ((frag->len & 7) && frag->next) ||
 824			    skb_headroom(frag) < hlen + ll_rs)
 825				goto slow_path_clean;
 826
 827			/* Partially cloned skb? */
 828			if (skb_shared(frag))
 829				goto slow_path_clean;
 830
 831			BUG_ON(frag->sk);
 832			if (skb->sk) {
 833				frag->sk = skb->sk;
 834				frag->destructor = sock_wfree;
 835			}
 836			skb->truesize -= frag->truesize;
 837		}
 838
 839		/* Everything is OK. Generate! */
 840		ip_fraglist_init(skb, iph, hlen, &iter);
 841
 842		for (;;) {
 843			/* Prepare header of the next frame,
 844			 * before previous one went down. */
 845			if (iter.frag) {
 846				ip_fraglist_ipcb_prepare(skb, &iter);
 
 
 847				ip_fraglist_prepare(skb, &iter);
 
 
 
 
 
 
 
 
 
 
 848			}
 849
 850			skb->tstamp = tstamp;
 851			err = output(net, sk, skb);
 852
 853			if (!err)
 854				IP_INC_STATS(net, IPSTATS_MIB_FRAGCREATES);
 855			if (err || !iter.frag)
 856				break;
 857
 858			skb = ip_fraglist_next(&iter);
 859		}
 860
 861		if (err == 0) {
 862			IP_INC_STATS(net, IPSTATS_MIB_FRAGOKS);
 863			return 0;
 864		}
 865
 866		kfree_skb_list(iter.frag);
 867
 868		IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
 869		return err;
 870
 871slow_path_clean:
 872		skb_walk_frags(skb, frag2) {
 873			if (frag2 == frag)
 874				break;
 875			frag2->sk = NULL;
 876			frag2->destructor = NULL;
 877			skb->truesize += frag2->truesize;
 878		}
 879	}
 880
 881slow_path:
 882	/*
 883	 *	Fragment the datagram.
 884	 */
 885
 886	ip_frag_init(skb, hlen, ll_rs, mtu, IPCB(skb)->flags & IPSKB_FRAG_PMTU,
 887		     &state);
 888
 889	/*
 890	 *	Keep copying data until we run out.
 891	 */
 892
 893	while (state.left > 0) {
 894		bool first_frag = (state.offset == 0);
 895
 896		skb2 = ip_frag_next(skb, &state);
 897		if (IS_ERR(skb2)) {
 898			err = PTR_ERR(skb2);
 899			goto fail;
 900		}
 901		ip_frag_ipcb(skb, skb2, first_frag, &state);
 902
 903		/*
 904		 *	Put this fragment into the sending queue.
 905		 */
 906		skb2->tstamp = tstamp;
 907		err = output(net, sk, skb2);
 908		if (err)
 909			goto fail;
 910
 911		IP_INC_STATS(net, IPSTATS_MIB_FRAGCREATES);
 912	}
 913	consume_skb(skb);
 914	IP_INC_STATS(net, IPSTATS_MIB_FRAGOKS);
 915	return err;
 916
 917fail:
 918	kfree_skb(skb);
 919	IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
 920	return err;
 921}
 922EXPORT_SYMBOL(ip_do_fragment);
 923
 924int
 925ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
 926{
 927	struct msghdr *msg = from;
 928
 929	if (skb->ip_summed == CHECKSUM_PARTIAL) {
 930		if (!copy_from_iter_full(to, len, &msg->msg_iter))
 931			return -EFAULT;
 932	} else {
 933		__wsum csum = 0;
 934		if (!csum_and_copy_from_iter_full(to, len, &csum, &msg->msg_iter))
 935			return -EFAULT;
 936		skb->csum = csum_block_add(skb->csum, csum, odd);
 937	}
 938	return 0;
 939}
 940EXPORT_SYMBOL(ip_generic_getfrag);
 941
 942static inline __wsum
 943csum_page(struct page *page, int offset, int copy)
 944{
 945	char *kaddr;
 946	__wsum csum;
 947	kaddr = kmap(page);
 948	csum = csum_partial(kaddr + offset, copy, 0);
 949	kunmap(page);
 950	return csum;
 951}
 952
 953static int __ip_append_data(struct sock *sk,
 954			    struct flowi4 *fl4,
 955			    struct sk_buff_head *queue,
 956			    struct inet_cork *cork,
 957			    struct page_frag *pfrag,
 958			    int getfrag(void *from, char *to, int offset,
 959					int len, int odd, struct sk_buff *skb),
 960			    void *from, int length, int transhdrlen,
 961			    unsigned int flags)
 962{
 963	struct inet_sock *inet = inet_sk(sk);
 964	struct ubuf_info *uarg = NULL;
 965	struct sk_buff *skb;
 966
 967	struct ip_options *opt = cork->opt;
 968	int hh_len;
 969	int exthdrlen;
 970	int mtu;
 971	int copy;
 972	int err;
 973	int offset = 0;
 
 974	unsigned int maxfraglen, fragheaderlen, maxnonfragsize;
 975	int csummode = CHECKSUM_NONE;
 976	struct rtable *rt = (struct rtable *)cork->dst;
 
 977	unsigned int wmem_alloc_delta = 0;
 978	bool paged, extra_uref = false;
 979	u32 tskey = 0;
 980
 981	skb = skb_peek_tail(queue);
 982
 983	exthdrlen = !skb ? rt->dst.header_len : 0;
 984	mtu = cork->gso_size ? IP_MAX_MTU : cork->fragsize;
 985	paged = !!cork->gso_size;
 986
 987	if (cork->tx_flags & SKBTX_ANY_SW_TSTAMP &&
 988	    sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID)
 989		tskey = sk->sk_tskey++;
 990
 991	hh_len = LL_RESERVED_SPACE(rt->dst.dev);
 992
 993	fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
 994	maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
 995	maxnonfragsize = ip_sk_ignore_df(sk) ? 0xFFFF : mtu;
 996
 997	if (cork->length + length > maxnonfragsize - fragheaderlen) {
 998		ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
 999			       mtu - (opt ? opt->optlen : 0));
1000		return -EMSGSIZE;
1001	}
1002
1003	/*
1004	 * transhdrlen > 0 means that this is the first fragment and we wish
1005	 * it won't be fragmented in the future.
1006	 */
1007	if (transhdrlen &&
1008	    length + fragheaderlen <= mtu &&
1009	    rt->dst.dev->features & (NETIF_F_HW_CSUM | NETIF_F_IP_CSUM) &&
1010	    (!(flags & MSG_MORE) || cork->gso_size) &&
1011	    (!exthdrlen || (rt->dst.dev->features & NETIF_F_HW_ESP_TX_CSUM)))
1012		csummode = CHECKSUM_PARTIAL;
1013
1014	if (flags & MSG_ZEROCOPY && length && sock_flag(sk, SOCK_ZEROCOPY)) {
1015		uarg = sock_zerocopy_realloc(sk, length, skb_zcopy(skb));
1016		if (!uarg)
1017			return -ENOBUFS;
1018		extra_uref = !skb_zcopy(skb);	/* only ref on new uarg */
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1019		if (rt->dst.dev->features & NETIF_F_SG &&
1020		    csummode == CHECKSUM_PARTIAL) {
 
1021			paged = true;
1022		} else {
1023			uarg->zerocopy = 0;
1024			skb_zcopy_set(skb, uarg, &extra_uref);
1025		}
1026	}
1027
1028	cork->length += length;
1029
 
 
 
 
 
1030	/* So, what's going on in the loop below?
1031	 *
1032	 * We use calculated fragment length to generate chained skb,
1033	 * each of segments is IP fragment ready for sending to network after
1034	 * adding appropriate IP header.
1035	 */
1036
1037	if (!skb)
1038		goto alloc_new_skb;
1039
1040	while (length > 0) {
1041		/* Check if the remaining data fits into current packet. */
1042		copy = mtu - skb->len;
1043		if (copy < length)
1044			copy = maxfraglen - skb->len;
1045		if (copy <= 0) {
1046			char *data;
1047			unsigned int datalen;
1048			unsigned int fraglen;
1049			unsigned int fraggap;
1050			unsigned int alloclen;
1051			unsigned int pagedlen;
1052			struct sk_buff *skb_prev;
1053alloc_new_skb:
1054			skb_prev = skb;
1055			if (skb_prev)
1056				fraggap = skb_prev->len - maxfraglen;
1057			else
1058				fraggap = 0;
1059
1060			/*
1061			 * If remaining data exceeds the mtu,
1062			 * we know we need more fragment(s).
1063			 */
1064			datalen = length + fraggap;
1065			if (datalen > mtu - fragheaderlen)
1066				datalen = maxfraglen - fragheaderlen;
1067			fraglen = datalen + fragheaderlen;
1068			pagedlen = 0;
1069
1070			if ((flags & MSG_MORE) &&
1071			    !(rt->dst.dev->features&NETIF_F_SG))
1072				alloclen = mtu;
1073			else if (!paged)
1074				alloclen = fraglen;
1075			else {
1076				alloclen = min_t(int, fraglen, MAX_HEADER);
1077				pagedlen = fraglen - alloclen;
1078			}
1079
1080			alloclen += exthdrlen;
1081
1082			/* The last fragment gets additional space at tail.
1083			 * Note, with MSG_MORE we overallocate on fragments,
1084			 * because we have no idea what fragment will be
1085			 * the last.
1086			 */
1087			if (datalen == length + fraggap)
1088				alloclen += rt->dst.trailer_len;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1089
1090			if (transhdrlen) {
1091				skb = sock_alloc_send_skb(sk,
1092						alloclen + hh_len + 15,
1093						(flags & MSG_DONTWAIT), &err);
1094			} else {
1095				skb = NULL;
1096				if (refcount_read(&sk->sk_wmem_alloc) + wmem_alloc_delta <=
1097				    2 * sk->sk_sndbuf)
1098					skb = alloc_skb(alloclen + hh_len + 15,
1099							sk->sk_allocation);
1100				if (unlikely(!skb))
1101					err = -ENOBUFS;
1102			}
1103			if (!skb)
1104				goto error;
1105
1106			/*
1107			 *	Fill in the control structures
1108			 */
1109			skb->ip_summed = csummode;
1110			skb->csum = 0;
1111			skb_reserve(skb, hh_len);
1112
1113			/*
1114			 *	Find where to start putting bytes.
1115			 */
1116			data = skb_put(skb, fraglen + exthdrlen - pagedlen);
1117			skb_set_network_header(skb, exthdrlen);
1118			skb->transport_header = (skb->network_header +
1119						 fragheaderlen);
1120			data += fragheaderlen + exthdrlen;
1121
1122			if (fraggap) {
1123				skb->csum = skb_copy_and_csum_bits(
1124					skb_prev, maxfraglen,
1125					data + transhdrlen, fraggap, 0);
1126				skb_prev->csum = csum_sub(skb_prev->csum,
1127							  skb->csum);
1128				data += fraggap;
1129				pskb_trim_unique(skb_prev, maxfraglen);
1130			}
1131
1132			copy = datalen - transhdrlen - fraggap - pagedlen;
 
 
 
1133			if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) {
1134				err = -EFAULT;
1135				kfree_skb(skb);
1136				goto error;
 
 
1137			}
1138
1139			offset += copy;
1140			length -= copy + transhdrlen;
1141			transhdrlen = 0;
1142			exthdrlen = 0;
1143			csummode = CHECKSUM_NONE;
1144
1145			/* only the initial fragment is time stamped */
1146			skb_shinfo(skb)->tx_flags = cork->tx_flags;
1147			cork->tx_flags = 0;
1148			skb_shinfo(skb)->tskey = tskey;
1149			tskey = 0;
1150			skb_zcopy_set(skb, uarg, &extra_uref);
1151
1152			if ((flags & MSG_CONFIRM) && !skb_prev)
1153				skb_set_dst_pending_confirm(skb, 1);
1154
1155			/*
1156			 * Put the packet on the pending queue.
1157			 */
1158			if (!skb->destructor) {
1159				skb->destructor = sock_wfree;
1160				skb->sk = sk;
1161				wmem_alloc_delta += skb->truesize;
1162			}
1163			__skb_queue_tail(queue, skb);
1164			continue;
1165		}
1166
1167		if (copy > length)
1168			copy = length;
1169
1170		if (!(rt->dst.dev->features&NETIF_F_SG) &&
1171		    skb_tailroom(skb) >= copy) {
1172			unsigned int off;
1173
1174			off = skb->len;
1175			if (getfrag(from, skb_put(skb, copy),
1176					offset, copy, off, skb) < 0) {
1177				__skb_trim(skb, off);
1178				err = -EFAULT;
1179				goto error;
1180			}
1181		} else if (!uarg || !uarg->zerocopy) {
 
 
 
 
 
 
 
 
 
 
 
 
 
1182			int i = skb_shinfo(skb)->nr_frags;
1183
1184			err = -ENOMEM;
1185			if (!sk_page_frag_refill(sk, pfrag))
1186				goto error;
1187
 
1188			if (!skb_can_coalesce(skb, i, pfrag->page,
1189					      pfrag->offset)) {
1190				err = -EMSGSIZE;
1191				if (i == MAX_SKB_FRAGS)
1192					goto error;
1193
1194				__skb_fill_page_desc(skb, i, pfrag->page,
1195						     pfrag->offset, 0);
1196				skb_shinfo(skb)->nr_frags = ++i;
1197				get_page(pfrag->page);
1198			}
1199			copy = min_t(int, copy, pfrag->size - pfrag->offset);
1200			if (getfrag(from,
1201				    page_address(pfrag->page) + pfrag->offset,
1202				    offset, copy, skb->len, skb) < 0)
1203				goto error_efault;
1204
1205			pfrag->offset += copy;
1206			skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
1207			skb->len += copy;
1208			skb->data_len += copy;
1209			skb->truesize += copy;
1210			wmem_alloc_delta += copy;
1211		} else {
1212			err = skb_zerocopy_iter_dgram(skb, from, copy);
1213			if (err < 0)
1214				goto error;
1215		}
1216		offset += copy;
1217		length -= copy;
1218	}
1219
1220	if (wmem_alloc_delta)
1221		refcount_add(wmem_alloc_delta, &sk->sk_wmem_alloc);
1222	return 0;
1223
1224error_efault:
1225	err = -EFAULT;
1226error:
1227	if (uarg)
1228		sock_zerocopy_put_abort(uarg, extra_uref);
1229	cork->length -= length;
1230	IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1231	refcount_add(wmem_alloc_delta, &sk->sk_wmem_alloc);
 
 
1232	return err;
1233}
1234
1235static int ip_setup_cork(struct sock *sk, struct inet_cork *cork,
1236			 struct ipcm_cookie *ipc, struct rtable **rtp)
1237{
1238	struct ip_options_rcu *opt;
1239	struct rtable *rt;
1240
1241	rt = *rtp;
1242	if (unlikely(!rt))
1243		return -EFAULT;
1244
 
 
 
 
 
 
1245	/*
1246	 * setup for corking.
1247	 */
1248	opt = ipc->opt;
1249	if (opt) {
1250		if (!cork->opt) {
1251			cork->opt = kmalloc(sizeof(struct ip_options) + 40,
1252					    sk->sk_allocation);
1253			if (unlikely(!cork->opt))
1254				return -ENOBUFS;
1255		}
1256		memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen);
1257		cork->flags |= IPCORK_OPT;
1258		cork->addr = ipc->addr;
1259	}
1260
1261	/*
1262	 * We steal reference to this route, caller should not release it
1263	 */
1264	*rtp = NULL;
1265	cork->fragsize = ip_sk_use_pmtu(sk) ?
1266			 dst_mtu(&rt->dst) : rt->dst.dev->mtu;
1267
1268	cork->gso_size = ipc->gso_size;
 
1269	cork->dst = &rt->dst;
 
 
 
1270	cork->length = 0;
1271	cork->ttl = ipc->ttl;
1272	cork->tos = ipc->tos;
1273	cork->mark = ipc->sockc.mark;
1274	cork->priority = ipc->priority;
1275	cork->transmit_time = ipc->sockc.transmit_time;
1276	cork->tx_flags = 0;
1277	sock_tx_timestamp(sk, ipc->sockc.tsflags, &cork->tx_flags);
1278
1279	return 0;
1280}
1281
1282/*
1283 *	ip_append_data() and ip_append_page() can make one large IP datagram
1284 *	from many pieces of data. Each pieces will be holded on the socket
1285 *	until ip_push_pending_frames() is called. Each piece can be a page
1286 *	or non-page data.
1287 *
1288 *	Not only UDP, other transport protocols - e.g. raw sockets - can use
1289 *	this interface potentially.
1290 *
1291 *	LATER: length must be adjusted by pad at tail, when it is required.
1292 */
1293int ip_append_data(struct sock *sk, struct flowi4 *fl4,
1294		   int getfrag(void *from, char *to, int offset, int len,
1295			       int odd, struct sk_buff *skb),
1296		   void *from, int length, int transhdrlen,
1297		   struct ipcm_cookie *ipc, struct rtable **rtp,
1298		   unsigned int flags)
1299{
1300	struct inet_sock *inet = inet_sk(sk);
1301	int err;
1302
1303	if (flags&MSG_PROBE)
1304		return 0;
1305
1306	if (skb_queue_empty(&sk->sk_write_queue)) {
1307		err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp);
1308		if (err)
1309			return err;
1310	} else {
1311		transhdrlen = 0;
1312	}
1313
1314	return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base,
1315				sk_page_frag(sk), getfrag,
1316				from, length, transhdrlen, flags);
1317}
1318
1319ssize_t	ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page,
1320		       int offset, size_t size, int flags)
1321{
1322	struct inet_sock *inet = inet_sk(sk);
1323	struct sk_buff *skb;
1324	struct rtable *rt;
1325	struct ip_options *opt = NULL;
1326	struct inet_cork *cork;
1327	int hh_len;
1328	int mtu;
1329	int len;
1330	int err;
1331	unsigned int maxfraglen, fragheaderlen, fraggap, maxnonfragsize;
1332
1333	if (inet->hdrincl)
1334		return -EPERM;
1335
1336	if (flags&MSG_PROBE)
1337		return 0;
1338
1339	if (skb_queue_empty(&sk->sk_write_queue))
1340		return -EINVAL;
1341
1342	cork = &inet->cork.base;
1343	rt = (struct rtable *)cork->dst;
1344	if (cork->flags & IPCORK_OPT)
1345		opt = cork->opt;
1346
1347	if (!(rt->dst.dev->features&NETIF_F_SG))
1348		return -EOPNOTSUPP;
1349
1350	hh_len = LL_RESERVED_SPACE(rt->dst.dev);
1351	mtu = cork->gso_size ? IP_MAX_MTU : cork->fragsize;
1352
1353	fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
1354	maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
1355	maxnonfragsize = ip_sk_ignore_df(sk) ? 0xFFFF : mtu;
1356
1357	if (cork->length + size > maxnonfragsize - fragheaderlen) {
1358		ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
1359			       mtu - (opt ? opt->optlen : 0));
1360		return -EMSGSIZE;
1361	}
1362
1363	skb = skb_peek_tail(&sk->sk_write_queue);
1364	if (!skb)
1365		return -EINVAL;
1366
1367	cork->length += size;
1368
1369	while (size > 0) {
1370		/* Check if the remaining data fits into current packet. */
1371		len = mtu - skb->len;
1372		if (len < size)
1373			len = maxfraglen - skb->len;
1374
1375		if (len <= 0) {
1376			struct sk_buff *skb_prev;
1377			int alloclen;
1378
1379			skb_prev = skb;
1380			fraggap = skb_prev->len - maxfraglen;
1381
1382			alloclen = fragheaderlen + hh_len + fraggap + 15;
1383			skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation);
1384			if (unlikely(!skb)) {
1385				err = -ENOBUFS;
1386				goto error;
1387			}
1388
1389			/*
1390			 *	Fill in the control structures
1391			 */
1392			skb->ip_summed = CHECKSUM_NONE;
1393			skb->csum = 0;
1394			skb_reserve(skb, hh_len);
1395
1396			/*
1397			 *	Find where to start putting bytes.
1398			 */
1399			skb_put(skb, fragheaderlen + fraggap);
1400			skb_reset_network_header(skb);
1401			skb->transport_header = (skb->network_header +
1402						 fragheaderlen);
1403			if (fraggap) {
1404				skb->csum = skb_copy_and_csum_bits(skb_prev,
1405								   maxfraglen,
1406						    skb_transport_header(skb),
1407								   fraggap, 0);
1408				skb_prev->csum = csum_sub(skb_prev->csum,
1409							  skb->csum);
1410				pskb_trim_unique(skb_prev, maxfraglen);
1411			}
1412
1413			/*
1414			 * Put the packet on the pending queue.
1415			 */
1416			__skb_queue_tail(&sk->sk_write_queue, skb);
1417			continue;
1418		}
1419
1420		if (len > size)
1421			len = size;
1422
1423		if (skb_append_pagefrags(skb, page, offset, len)) {
1424			err = -EMSGSIZE;
1425			goto error;
1426		}
1427
1428		if (skb->ip_summed == CHECKSUM_NONE) {
1429			__wsum csum;
1430			csum = csum_page(page, offset, len);
1431			skb->csum = csum_block_add(skb->csum, csum, skb->len);
1432		}
1433
1434		skb->len += len;
1435		skb->data_len += len;
1436		skb->truesize += len;
1437		refcount_add(len, &sk->sk_wmem_alloc);
1438		offset += len;
1439		size -= len;
1440	}
1441	return 0;
1442
1443error:
1444	cork->length -= size;
1445	IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1446	return err;
1447}
1448
1449static void ip_cork_release(struct inet_cork *cork)
1450{
1451	cork->flags &= ~IPCORK_OPT;
1452	kfree(cork->opt);
1453	cork->opt = NULL;
1454	dst_release(cork->dst);
1455	cork->dst = NULL;
1456}
1457
1458/*
1459 *	Combined all pending IP fragments on the socket as one IP datagram
1460 *	and push them out.
1461 */
1462struct sk_buff *__ip_make_skb(struct sock *sk,
1463			      struct flowi4 *fl4,
1464			      struct sk_buff_head *queue,
1465			      struct inet_cork *cork)
1466{
1467	struct sk_buff *skb, *tmp_skb;
1468	struct sk_buff **tail_skb;
1469	struct inet_sock *inet = inet_sk(sk);
1470	struct net *net = sock_net(sk);
1471	struct ip_options *opt = NULL;
1472	struct rtable *rt = (struct rtable *)cork->dst;
1473	struct iphdr *iph;
 
1474	__be16 df = 0;
1475	__u8 ttl;
1476
1477	skb = __skb_dequeue(queue);
1478	if (!skb)
1479		goto out;
1480	tail_skb = &(skb_shinfo(skb)->frag_list);
1481
1482	/* move skb->data to ip header from ext header */
1483	if (skb->data < skb_network_header(skb))
1484		__skb_pull(skb, skb_network_offset(skb));
1485	while ((tmp_skb = __skb_dequeue(queue)) != NULL) {
1486		__skb_pull(tmp_skb, skb_network_header_len(skb));
1487		*tail_skb = tmp_skb;
1488		tail_skb = &(tmp_skb->next);
1489		skb->len += tmp_skb->len;
1490		skb->data_len += tmp_skb->len;
1491		skb->truesize += tmp_skb->truesize;
1492		tmp_skb->destructor = NULL;
1493		tmp_skb->sk = NULL;
1494	}
1495
1496	/* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow
1497	 * to fragment the frame generated here. No matter, what transforms
1498	 * how transforms change size of the packet, it will come out.
1499	 */
1500	skb->ignore_df = ip_sk_ignore_df(sk);
1501
1502	/* DF bit is set when we want to see DF on outgoing frames.
1503	 * If ignore_df is set too, we still allow to fragment this frame
1504	 * locally. */
1505	if (inet->pmtudisc == IP_PMTUDISC_DO ||
1506	    inet->pmtudisc == IP_PMTUDISC_PROBE ||
 
1507	    (skb->len <= dst_mtu(&rt->dst) &&
1508	     ip_dont_fragment(sk, &rt->dst)))
1509		df = htons(IP_DF);
1510
1511	if (cork->flags & IPCORK_OPT)
1512		opt = cork->opt;
1513
1514	if (cork->ttl != 0)
1515		ttl = cork->ttl;
1516	else if (rt->rt_type == RTN_MULTICAST)
1517		ttl = inet->mc_ttl;
1518	else
1519		ttl = ip_select_ttl(inet, &rt->dst);
1520
1521	iph = ip_hdr(skb);
1522	iph->version = 4;
1523	iph->ihl = 5;
1524	iph->tos = (cork->tos != -1) ? cork->tos : inet->tos;
1525	iph->frag_off = df;
1526	iph->ttl = ttl;
1527	iph->protocol = sk->sk_protocol;
1528	ip_copy_addrs(iph, fl4);
1529	ip_select_ident(net, skb, sk);
1530
1531	if (opt) {
1532		iph->ihl += opt->optlen>>2;
1533		ip_options_build(skb, opt, cork->addr, rt, 0);
1534	}
1535
1536	skb->priority = (cork->tos != -1) ? cork->priority: sk->sk_priority;
1537	skb->mark = cork->mark;
1538	skb->tstamp = cork->transmit_time;
1539	/*
1540	 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec
1541	 * on dst refcount
1542	 */
1543	cork->dst = NULL;
1544	skb_dst_set(skb, &rt->dst);
1545
1546	if (iph->protocol == IPPROTO_ICMP)
1547		icmp_out_count(net, ((struct icmphdr *)
1548			skb_transport_header(skb))->type);
 
 
 
 
 
 
 
 
 
 
 
1549
1550	ip_cork_release(cork);
1551out:
1552	return skb;
1553}
1554
1555int ip_send_skb(struct net *net, struct sk_buff *skb)
1556{
1557	int err;
1558
1559	err = ip_local_out(net, skb->sk, skb);
1560	if (err) {
1561		if (err > 0)
1562			err = net_xmit_errno(err);
1563		if (err)
1564			IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS);
1565	}
1566
1567	return err;
1568}
1569
1570int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4)
1571{
1572	struct sk_buff *skb;
1573
1574	skb = ip_finish_skb(sk, fl4);
1575	if (!skb)
1576		return 0;
1577
1578	/* Netfilter gets whole the not fragmented skb. */
1579	return ip_send_skb(sock_net(sk), skb);
1580}
1581
1582/*
1583 *	Throw away all pending data on the socket.
1584 */
1585static void __ip_flush_pending_frames(struct sock *sk,
1586				      struct sk_buff_head *queue,
1587				      struct inet_cork *cork)
1588{
1589	struct sk_buff *skb;
1590
1591	while ((skb = __skb_dequeue_tail(queue)) != NULL)
1592		kfree_skb(skb);
1593
1594	ip_cork_release(cork);
1595}
1596
1597void ip_flush_pending_frames(struct sock *sk)
1598{
1599	__ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork.base);
1600}
1601
1602struct sk_buff *ip_make_skb(struct sock *sk,
1603			    struct flowi4 *fl4,
1604			    int getfrag(void *from, char *to, int offset,
1605					int len, int odd, struct sk_buff *skb),
1606			    void *from, int length, int transhdrlen,
1607			    struct ipcm_cookie *ipc, struct rtable **rtp,
1608			    struct inet_cork *cork, unsigned int flags)
1609{
1610	struct sk_buff_head queue;
1611	int err;
1612
1613	if (flags & MSG_PROBE)
1614		return NULL;
1615
1616	__skb_queue_head_init(&queue);
1617
1618	cork->flags = 0;
1619	cork->addr = 0;
1620	cork->opt = NULL;
1621	err = ip_setup_cork(sk, cork, ipc, rtp);
1622	if (err)
1623		return ERR_PTR(err);
1624
1625	err = __ip_append_data(sk, fl4, &queue, cork,
1626			       &current->task_frag, getfrag,
1627			       from, length, transhdrlen, flags);
1628	if (err) {
1629		__ip_flush_pending_frames(sk, &queue, cork);
1630		return ERR_PTR(err);
1631	}
1632
1633	return __ip_make_skb(sk, fl4, &queue, cork);
1634}
1635
1636/*
1637 *	Fetch data from kernel space and fill in checksum if needed.
1638 */
1639static int ip_reply_glue_bits(void *dptr, char *to, int offset,
1640			      int len, int odd, struct sk_buff *skb)
1641{
1642	__wsum csum;
1643
1644	csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0);
1645	skb->csum = csum_block_add(skb->csum, csum, odd);
1646	return 0;
1647}
1648
1649/*
1650 *	Generic function to send a packet as reply to another packet.
1651 *	Used to send some TCP resets/acks so far.
1652 */
1653void ip_send_unicast_reply(struct sock *sk, struct sk_buff *skb,
1654			   const struct ip_options *sopt,
1655			   __be32 daddr, __be32 saddr,
1656			   const struct ip_reply_arg *arg,
1657			   unsigned int len, u64 transmit_time)
1658{
1659	struct ip_options_data replyopts;
1660	struct ipcm_cookie ipc;
1661	struct flowi4 fl4;
1662	struct rtable *rt = skb_rtable(skb);
1663	struct net *net = sock_net(sk);
1664	struct sk_buff *nskb;
1665	int err;
1666	int oif;
1667
1668	if (__ip_options_echo(net, &replyopts.opt.opt, skb, sopt))
1669		return;
1670
1671	ipcm_init(&ipc);
1672	ipc.addr = daddr;
1673	ipc.sockc.transmit_time = transmit_time;
1674
1675	if (replyopts.opt.opt.optlen) {
1676		ipc.opt = &replyopts.opt;
1677
1678		if (replyopts.opt.opt.srr)
1679			daddr = replyopts.opt.opt.faddr;
1680	}
1681
1682	oif = arg->bound_dev_if;
1683	if (!oif && netif_index_is_l3_master(net, skb->skb_iif))
1684		oif = skb->skb_iif;
1685
1686	flowi4_init_output(&fl4, oif,
1687			   IP4_REPLY_MARK(net, skb->mark) ?: sk->sk_mark,
1688			   RT_TOS(arg->tos),
1689			   RT_SCOPE_UNIVERSE, ip_hdr(skb)->protocol,
1690			   ip_reply_arg_flowi_flags(arg),
1691			   daddr, saddr,
1692			   tcp_hdr(skb)->source, tcp_hdr(skb)->dest,
1693			   arg->uid);
1694	security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
1695	rt = ip_route_output_key(net, &fl4);
1696	if (IS_ERR(rt))
1697		return;
1698
1699	inet_sk(sk)->tos = arg->tos;
1700
1701	sk->sk_protocol = ip_hdr(skb)->protocol;
1702	sk->sk_bound_dev_if = arg->bound_dev_if;
1703	sk->sk_sndbuf = sysctl_wmem_default;
1704	sk->sk_mark = fl4.flowi4_mark;
1705	err = ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base,
1706			     len, 0, &ipc, &rt, MSG_DONTWAIT);
1707	if (unlikely(err)) {
1708		ip_flush_pending_frames(sk);
1709		goto out;
1710	}
1711
1712	nskb = skb_peek(&sk->sk_write_queue);
1713	if (nskb) {
1714		if (arg->csumoffset >= 0)
1715			*((__sum16 *)skb_transport_header(nskb) +
1716			  arg->csumoffset) = csum_fold(csum_add(nskb->csum,
1717								arg->csum));
1718		nskb->ip_summed = CHECKSUM_NONE;
 
 
 
1719		ip_push_pending_frames(sk, &fl4);
1720	}
1721out:
1722	ip_rt_put(rt);
1723}
1724
1725void __init ip_init(void)
1726{
1727	ip_rt_init();
1728	inet_initpeers();
1729
1730#if defined(CONFIG_IP_MULTICAST)
1731	igmp_mc_init();
1732#endif
1733}