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 <linux/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 <net/lwtunnel.h>
  77#include <linux/bpf-cgroup.h>
  78#include <linux/igmp.h>
  79#include <linux/netfilter_ipv4.h>
  80#include <linux/netfilter_bridge.h>
  81#include <linux/netlink.h>
  82#include <linux/tcp.h>
  83
  84static int
  85ip_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
  86	    unsigned int mtu,
  87	    int (*output)(struct net *, struct sock *, struct sk_buff *));
  88
  89/* Generate a checksum for an outgoing IP datagram. */
  90void ip_send_check(struct iphdr *iph)
  91{
  92	iph->check = 0;
  93	iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
  94}
  95EXPORT_SYMBOL(ip_send_check);
  96
  97int __ip_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
  98{
  99	struct iphdr *iph = ip_hdr(skb);
 100
 101	iph->tot_len = htons(skb->len);
 102	ip_send_check(iph);
 103
 104	/* if egress device is enslaved to an L3 master device pass the
 105	 * skb to its handler for processing
 106	 */
 107	skb = l3mdev_ip_out(sk, skb);
 108	if (unlikely(!skb))
 109		return 0;
 110
 111	skb->protocol = htons(ETH_P_IP);
 112
 113	return nf_hook(NFPROTO_IPV4, NF_INET_LOCAL_OUT,
 114		       net, sk, skb, NULL, skb_dst(skb)->dev,
 115		       dst_output);
 116}
 117
 118int ip_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
 119{
 120	int err;
 121
 122	err = __ip_local_out(net, sk, skb);
 123	if (likely(err == 1))
 124		err = dst_output(net, sk, skb);
 125
 126	return err;
 127}
 128EXPORT_SYMBOL_GPL(ip_local_out);
 129
 130static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst)
 131{
 132	int ttl = inet->uc_ttl;
 133
 134	if (ttl < 0)
 135		ttl = ip4_dst_hoplimit(dst);
 136	return ttl;
 137}
 138
 139/*
 140 *		Add an ip header to a skbuff and send it out.
 141 *
 142 */
 143int ip_build_and_send_pkt(struct sk_buff *skb, const struct sock *sk,
 144			  __be32 saddr, __be32 daddr, struct ip_options_rcu *opt)
 145{
 146	struct inet_sock *inet = inet_sk(sk);
 147	struct rtable *rt = skb_rtable(skb);
 148	struct net *net = sock_net(sk);
 149	struct iphdr *iph;
 150
 151	/* Build the IP header. */
 152	skb_push(skb, sizeof(struct iphdr) + (opt ? opt->opt.optlen : 0));
 153	skb_reset_network_header(skb);
 154	iph = ip_hdr(skb);
 155	iph->version  = 4;
 156	iph->ihl      = 5;
 157	iph->tos      = inet->tos;
 158	iph->ttl      = ip_select_ttl(inet, &rt->dst);
 159	iph->daddr    = (opt && opt->opt.srr ? opt->opt.faddr : daddr);
 160	iph->saddr    = saddr;
 161	iph->protocol = sk->sk_protocol;
 162	if (ip_dont_fragment(sk, &rt->dst)) {
 163		iph->frag_off = htons(IP_DF);
 164		iph->id = 0;
 165	} else {
 166		iph->frag_off = 0;
 167		__ip_select_ident(net, iph, 1);
 168	}
 169
 170	if (opt && opt->opt.optlen) {
 171		iph->ihl += opt->opt.optlen>>2;
 172		ip_options_build(skb, &opt->opt, daddr, rt, 0);
 173	}
 174
 175	skb->priority = sk->sk_priority;
 176	if (!skb->mark)
 177		skb->mark = sk->sk_mark;
 178
 179	/* Send it out. */
 180	return ip_local_out(net, skb->sk, skb);
 181}
 182EXPORT_SYMBOL_GPL(ip_build_and_send_pkt);
 183
 184static int ip_finish_output2(struct net *net, struct sock *sk, struct sk_buff *skb)
 185{
 186	struct dst_entry *dst = skb_dst(skb);
 187	struct rtable *rt = (struct rtable *)dst;
 188	struct net_device *dev = dst->dev;
 189	unsigned int hh_len = LL_RESERVED_SPACE(dev);
 190	struct neighbour *neigh;
 191	u32 nexthop;
 192
 193	if (rt->rt_type == RTN_MULTICAST) {
 194		IP_UPD_PO_STATS(net, IPSTATS_MIB_OUTMCAST, skb->len);
 195	} else if (rt->rt_type == RTN_BROADCAST)
 196		IP_UPD_PO_STATS(net, IPSTATS_MIB_OUTBCAST, skb->len);
 197
 198	/* Be paranoid, rather than too clever. */
 199	if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) {
 200		struct sk_buff *skb2;
 201
 202		skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev));
 203		if (!skb2) {
 204			kfree_skb(skb);
 205			return -ENOMEM;
 206		}
 207		if (skb->sk)
 208			skb_set_owner_w(skb2, skb->sk);
 209		consume_skb(skb);
 210		skb = skb2;
 211	}
 212
 213	if (lwtunnel_xmit_redirect(dst->lwtstate)) {
 214		int res = lwtunnel_xmit(skb);
 215
 216		if (res < 0 || res == LWTUNNEL_XMIT_DONE)
 217			return res;
 218	}
 219
 220	rcu_read_lock_bh();
 221	nexthop = (__force u32) rt_nexthop(rt, ip_hdr(skb)->daddr);
 222	neigh = __ipv4_neigh_lookup_noref(dev, nexthop);
 223	if (unlikely(!neigh))
 224		neigh = __neigh_create(&arp_tbl, &nexthop, dev, false);
 225	if (!IS_ERR(neigh)) {
 226		int res;
 227
 228		sock_confirm_neigh(skb, neigh);
 229		res = neigh_output(neigh, skb);
 230
 231		rcu_read_unlock_bh();
 232		return res;
 233	}
 234	rcu_read_unlock_bh();
 235
 236	net_dbg_ratelimited("%s: No header cache and no neighbour!\n",
 237			    __func__);
 238	kfree_skb(skb);
 239	return -EINVAL;
 240}
 241
 242static int ip_finish_output_gso(struct net *net, struct sock *sk,
 243				struct sk_buff *skb, unsigned int mtu)
 244{
 245	netdev_features_t features;
 246	struct sk_buff *segs;
 247	int ret = 0;
 248
 249	/* common case: seglen is <= mtu
 250	 */
 251	if (skb_gso_validate_network_len(skb, mtu))
 252		return ip_finish_output2(net, sk, skb);
 253
 254	/* Slowpath -  GSO segment length exceeds the egress MTU.
 255	 *
 256	 * This can happen in several cases:
 257	 *  - Forwarding of a TCP GRO skb, when DF flag is not set.
 258	 *  - Forwarding of an skb that arrived on a virtualization interface
 259	 *    (virtio-net/vhost/tap) with TSO/GSO size set by other network
 260	 *    stack.
 261	 *  - Local GSO skb transmitted on an NETIF_F_TSO tunnel stacked over an
 262	 *    interface with a smaller MTU.
 263	 *  - Arriving GRO skb (or GSO skb in a virtualized environment) that is
 264	 *    bridged to a NETIF_F_TSO tunnel stacked over an interface with an
 265	 *    insufficent MTU.
 266	 */
 267	features = netif_skb_features(skb);
 268	BUILD_BUG_ON(sizeof(*IPCB(skb)) > SKB_SGO_CB_OFFSET);
 269	segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK);
 270	if (IS_ERR_OR_NULL(segs)) {
 271		kfree_skb(skb);
 272		return -ENOMEM;
 273	}
 274
 275	consume_skb(skb);
 276
 277	do {
 278		struct sk_buff *nskb = segs->next;
 279		int err;
 280
 281		segs->next = NULL;
 282		err = ip_fragment(net, sk, segs, mtu, ip_finish_output2);
 283
 284		if (err && ret == 0)
 285			ret = err;
 286		segs = nskb;
 287	} while (segs);
 288
 289	return ret;
 290}
 291
 292static int ip_finish_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 293{
 294	unsigned int mtu;
 295	int ret;
 296
 297	ret = BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb);
 298	if (ret) {
 299		kfree_skb(skb);
 300		return ret;
 301	}
 302
 303#if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
 304	/* Policy lookup after SNAT yielded a new policy */
 305	if (skb_dst(skb)->xfrm) {
 306		IPCB(skb)->flags |= IPSKB_REROUTED;
 307		return dst_output(net, sk, skb);
 308	}
 309#endif
 310	mtu = ip_skb_dst_mtu(sk, skb);
 311	if (skb_is_gso(skb))
 312		return ip_finish_output_gso(net, sk, skb, mtu);
 313
 314	if (skb->len > mtu || (IPCB(skb)->flags & IPSKB_FRAG_PMTU))
 315		return ip_fragment(net, sk, skb, mtu, ip_finish_output2);
 316
 317	return ip_finish_output2(net, sk, skb);
 318}
 319
 320static int ip_mc_finish_output(struct net *net, struct sock *sk,
 321			       struct sk_buff *skb)
 322{
 323	int ret;
 324
 325	ret = BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb);
 326	if (ret) {
 327		kfree_skb(skb);
 328		return ret;
 329	}
 330
 331	return dev_loopback_xmit(net, sk, skb);
 332}
 333
 334int ip_mc_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 335{
 336	struct rtable *rt = skb_rtable(skb);
 337	struct net_device *dev = rt->dst.dev;
 338
 339	/*
 340	 *	If the indicated interface is up and running, send the packet.
 341	 */
 342	IP_UPD_PO_STATS(net, IPSTATS_MIB_OUT, skb->len);
 343
 344	skb->dev = dev;
 345	skb->protocol = htons(ETH_P_IP);
 346
 347	/*
 348	 *	Multicasts are looped back for other local users
 349	 */
 350
 351	if (rt->rt_flags&RTCF_MULTICAST) {
 352		if (sk_mc_loop(sk)
 353#ifdef CONFIG_IP_MROUTE
 354		/* Small optimization: do not loopback not local frames,
 355		   which returned after forwarding; they will be  dropped
 356		   by ip_mr_input in any case.
 357		   Note, that local frames are looped back to be delivered
 358		   to local recipients.
 359
 360		   This check is duplicated in ip_mr_input at the moment.
 361		 */
 362		    &&
 363		    ((rt->rt_flags & RTCF_LOCAL) ||
 364		     !(IPCB(skb)->flags & IPSKB_FORWARDED))
 365#endif
 366		   ) {
 367			struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
 368			if (newskb)
 369				NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
 370					net, sk, newskb, NULL, newskb->dev,
 371					ip_mc_finish_output);
 372		}
 373
 374		/* Multicasts with ttl 0 must not go beyond the host */
 375
 376		if (ip_hdr(skb)->ttl == 0) {
 377			kfree_skb(skb);
 378			return 0;
 379		}
 380	}
 381
 382	if (rt->rt_flags&RTCF_BROADCAST) {
 383		struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
 384		if (newskb)
 385			NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
 386				net, sk, newskb, NULL, newskb->dev,
 387				ip_mc_finish_output);
 388	}
 389
 390	return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
 391			    net, sk, skb, NULL, skb->dev,
 392			    ip_finish_output,
 393			    !(IPCB(skb)->flags & IPSKB_REROUTED));
 394}
 395
 396int ip_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 397{
 398	struct net_device *dev = skb_dst(skb)->dev;
 399
 400	IP_UPD_PO_STATS(net, IPSTATS_MIB_OUT, skb->len);
 401
 402	skb->dev = dev;
 403	skb->protocol = htons(ETH_P_IP);
 404
 405	return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
 406			    net, sk, skb, NULL, dev,
 407			    ip_finish_output,
 408			    !(IPCB(skb)->flags & IPSKB_REROUTED));
 409}
 410
 411/*
 412 * copy saddr and daddr, possibly using 64bit load/stores
 413 * Equivalent to :
 414 *   iph->saddr = fl4->saddr;
 415 *   iph->daddr = fl4->daddr;
 416 */
 417static void ip_copy_addrs(struct iphdr *iph, const struct flowi4 *fl4)
 418{
 419	BUILD_BUG_ON(offsetof(typeof(*fl4), daddr) !=
 420		     offsetof(typeof(*fl4), saddr) + sizeof(fl4->saddr));
 421	memcpy(&iph->saddr, &fl4->saddr,
 422	       sizeof(fl4->saddr) + sizeof(fl4->daddr));
 423}
 424
 425/* Note: skb->sk can be different from sk, in case of tunnels */
 426int ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl)
 427{
 428	struct inet_sock *inet = inet_sk(sk);
 429	struct net *net = sock_net(sk);
 430	struct ip_options_rcu *inet_opt;
 431	struct flowi4 *fl4;
 432	struct rtable *rt;
 433	struct iphdr *iph;
 434	int res;
 435
 436	/* Skip all of this if the packet is already routed,
 437	 * f.e. by something like SCTP.
 438	 */
 439	rcu_read_lock();
 440	inet_opt = rcu_dereference(inet->inet_opt);
 441	fl4 = &fl->u.ip4;
 442	rt = skb_rtable(skb);
 443	if (rt)
 444		goto packet_routed;
 445
 446	/* Make sure we can route this packet. */
 447	rt = (struct rtable *)__sk_dst_check(sk, 0);
 448	if (!rt) {
 449		__be32 daddr;
 450
 451		/* Use correct destination address if we have options. */
 452		daddr = inet->inet_daddr;
 453		if (inet_opt && inet_opt->opt.srr)
 454			daddr = inet_opt->opt.faddr;
 455
 456		/* If this fails, retransmit mechanism of transport layer will
 457		 * keep trying until route appears or the connection times
 458		 * itself out.
 459		 */
 460		rt = ip_route_output_ports(net, fl4, sk,
 461					   daddr, inet->inet_saddr,
 462					   inet->inet_dport,
 463					   inet->inet_sport,
 464					   sk->sk_protocol,
 465					   RT_CONN_FLAGS(sk),
 466					   sk->sk_bound_dev_if);
 467		if (IS_ERR(rt))
 468			goto no_route;
 469		sk_setup_caps(sk, &rt->dst);
 470	}
 471	skb_dst_set_noref(skb, &rt->dst);
 472
 473packet_routed:
 474	if (inet_opt && inet_opt->opt.is_strictroute && rt->rt_uses_gateway)
 475		goto no_route;
 476
 477	/* OK, we know where to send it, allocate and build IP header. */
 478	skb_push(skb, sizeof(struct iphdr) + (inet_opt ? inet_opt->opt.optlen : 0));
 479	skb_reset_network_header(skb);
 480	iph = ip_hdr(skb);
 481	*((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (inet->tos & 0xff));
 482	if (ip_dont_fragment(sk, &rt->dst) && !skb->ignore_df)
 483		iph->frag_off = htons(IP_DF);
 484	else
 485		iph->frag_off = 0;
 486	iph->ttl      = ip_select_ttl(inet, &rt->dst);
 487	iph->protocol = sk->sk_protocol;
 488	ip_copy_addrs(iph, fl4);
 489
 490	/* Transport layer set skb->h.foo itself. */
 491
 492	if (inet_opt && inet_opt->opt.optlen) {
 493		iph->ihl += inet_opt->opt.optlen >> 2;
 494		ip_options_build(skb, &inet_opt->opt, inet->inet_daddr, rt, 0);
 495	}
 496
 497	ip_select_ident_segs(net, skb, sk,
 498			     skb_shinfo(skb)->gso_segs ?: 1);
 499
 500	/* TODO : should we use skb->sk here instead of sk ? */
 501	skb->priority = sk->sk_priority;
 502	skb->mark = sk->sk_mark;
 503
 504	res = ip_local_out(net, sk, skb);
 505	rcu_read_unlock();
 506	return res;
 507
 508no_route:
 509	rcu_read_unlock();
 510	IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
 511	kfree_skb(skb);
 512	return -EHOSTUNREACH;
 513}
 514EXPORT_SYMBOL(ip_queue_xmit);
 515
 516static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from)
 517{
 518	to->pkt_type = from->pkt_type;
 519	to->priority = from->priority;
 520	to->protocol = from->protocol;
 521	skb_dst_drop(to);
 522	skb_dst_copy(to, from);
 523	to->dev = from->dev;
 524	to->mark = from->mark;
 525
 526	/* Copy the flags to each fragment. */
 527	IPCB(to)->flags = IPCB(from)->flags;
 528
 529#ifdef CONFIG_NET_SCHED
 530	to->tc_index = from->tc_index;
 531#endif
 532	nf_copy(to, from);
 533#if IS_ENABLED(CONFIG_IP_VS)
 534	to->ipvs_property = from->ipvs_property;
 535#endif
 536	skb_copy_secmark(to, from);
 537}
 538
 539static int ip_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
 540		       unsigned int mtu,
 541		       int (*output)(struct net *, struct sock *, struct sk_buff *))
 542{
 543	struct iphdr *iph = ip_hdr(skb);
 544
 545	if ((iph->frag_off & htons(IP_DF)) == 0)
 546		return ip_do_fragment(net, sk, skb, output);
 547
 548	if (unlikely(!skb->ignore_df ||
 549		     (IPCB(skb)->frag_max_size &&
 550		      IPCB(skb)->frag_max_size > mtu))) {
 551		IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
 552		icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
 553			  htonl(mtu));
 554		kfree_skb(skb);
 555		return -EMSGSIZE;
 556	}
 557
 558	return ip_do_fragment(net, sk, skb, output);
 559}
 560
 561/*
 562 *	This IP datagram is too large to be sent in one piece.  Break it up into
 563 *	smaller pieces (each of size equal to IP header plus
 564 *	a block of the data of the original IP data part) that will yet fit in a
 565 *	single device frame, and queue such a frame for sending.
 566 */
 567
 568int ip_do_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
 569		   int (*output)(struct net *, struct sock *, struct sk_buff *))
 570{
 571	struct iphdr *iph;
 572	int ptr;
 573	struct sk_buff *skb2;
 574	unsigned int mtu, hlen, left, len, ll_rs;
 575	int offset;
 576	__be16 not_last_frag;
 577	struct rtable *rt = skb_rtable(skb);
 578	int err = 0;
 579
 580	/* for offloaded checksums cleanup checksum before fragmentation */
 581	if (skb->ip_summed == CHECKSUM_PARTIAL &&
 582	    (err = skb_checksum_help(skb)))
 583		goto fail;
 584
 585	/*
 586	 *	Point into the IP datagram header.
 587	 */
 588
 589	iph = ip_hdr(skb);
 590
 591	mtu = ip_skb_dst_mtu(sk, skb);
 592	if (IPCB(skb)->frag_max_size && IPCB(skb)->frag_max_size < mtu)
 593		mtu = IPCB(skb)->frag_max_size;
 594
 595	/*
 596	 *	Setup starting values.
 597	 */
 598
 599	hlen = iph->ihl * 4;
 600	mtu = mtu - hlen;	/* Size of data space */
 601	IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE;
 602	ll_rs = LL_RESERVED_SPACE(rt->dst.dev);
 603
 604	/* When frag_list is given, use it. First, check its validity:
 605	 * some transformers could create wrong frag_list or break existing
 606	 * one, it is not prohibited. In this case fall back to copying.
 607	 *
 608	 * LATER: this step can be merged to real generation of fragments,
 609	 * we can switch to copy when see the first bad fragment.
 610	 */
 611	if (skb_has_frag_list(skb)) {
 612		struct sk_buff *frag, *frag2;
 613		unsigned int first_len = skb_pagelen(skb);
 614
 615		if (first_len - hlen > mtu ||
 616		    ((first_len - hlen) & 7) ||
 617		    ip_is_fragment(iph) ||
 618		    skb_cloned(skb) ||
 619		    skb_headroom(skb) < ll_rs)
 620			goto slow_path;
 621
 622		skb_walk_frags(skb, frag) {
 623			/* Correct geometry. */
 624			if (frag->len > mtu ||
 625			    ((frag->len & 7) && frag->next) ||
 626			    skb_headroom(frag) < hlen + ll_rs)
 627				goto slow_path_clean;
 628
 629			/* Partially cloned skb? */
 630			if (skb_shared(frag))
 631				goto slow_path_clean;
 632
 633			BUG_ON(frag->sk);
 634			if (skb->sk) {
 635				frag->sk = skb->sk;
 636				frag->destructor = sock_wfree;
 637			}
 638			skb->truesize -= frag->truesize;
 639		}
 640
 641		/* Everything is OK. Generate! */
 642
 643		err = 0;
 644		offset = 0;
 645		frag = skb_shinfo(skb)->frag_list;
 646		skb_frag_list_init(skb);
 647		skb->data_len = first_len - skb_headlen(skb);
 648		skb->len = first_len;
 649		iph->tot_len = htons(first_len);
 650		iph->frag_off = htons(IP_MF);
 651		ip_send_check(iph);
 652
 653		for (;;) {
 654			/* Prepare header of the next frame,
 655			 * before previous one went down. */
 656			if (frag) {
 657				frag->ip_summed = CHECKSUM_NONE;
 658				skb_reset_transport_header(frag);
 659				__skb_push(frag, hlen);
 660				skb_reset_network_header(frag);
 661				memcpy(skb_network_header(frag), iph, hlen);
 662				iph = ip_hdr(frag);
 663				iph->tot_len = htons(frag->len);
 664				ip_copy_metadata(frag, skb);
 665				if (offset == 0)
 666					ip_options_fragment(frag);
 667				offset += skb->len - hlen;
 668				iph->frag_off = htons(offset>>3);
 669				if (frag->next)
 670					iph->frag_off |= htons(IP_MF);
 671				/* Ready, complete checksum */
 672				ip_send_check(iph);
 673			}
 674
 675			err = output(net, sk, skb);
 676
 677			if (!err)
 678				IP_INC_STATS(net, IPSTATS_MIB_FRAGCREATES);
 679			if (err || !frag)
 680				break;
 681
 682			skb = frag;
 683			frag = skb->next;
 684			skb->next = NULL;
 685		}
 686
 687		if (err == 0) {
 688			IP_INC_STATS(net, IPSTATS_MIB_FRAGOKS);
 689			return 0;
 690		}
 691
 692		while (frag) {
 693			skb = frag->next;
 694			kfree_skb(frag);
 695			frag = skb;
 696		}
 697		IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
 698		return err;
 699
 700slow_path_clean:
 701		skb_walk_frags(skb, frag2) {
 702			if (frag2 == frag)
 703				break;
 704			frag2->sk = NULL;
 705			frag2->destructor = NULL;
 706			skb->truesize += frag2->truesize;
 707		}
 708	}
 709
 710slow_path:
 711	iph = ip_hdr(skb);
 712
 713	left = skb->len - hlen;		/* Space per frame */
 714	ptr = hlen;		/* Where to start from */
 715
 
 
 716	/*
 717	 *	Fragment the datagram.
 718	 */
 719
 720	offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3;
 721	not_last_frag = iph->frag_off & htons(IP_MF);
 722
 723	/*
 724	 *	Keep copying data until we run out.
 725	 */
 726
 727	while (left > 0) {
 728		len = left;
 729		/* IF: it doesn't fit, use 'mtu' - the data space left */
 730		if (len > mtu)
 731			len = mtu;
 732		/* IF: we are not sending up to and including the packet end
 733		   then align the next start on an eight byte boundary */
 734		if (len < left)	{
 735			len &= ~7;
 736		}
 737
 738		/* Allocate buffer */
 739		skb2 = alloc_skb(len + hlen + ll_rs, GFP_ATOMIC);
 740		if (!skb2) {
 741			err = -ENOMEM;
 742			goto fail;
 743		}
 744
 745		/*
 746		 *	Set up data on packet
 747		 */
 748
 749		ip_copy_metadata(skb2, skb);
 750		skb_reserve(skb2, ll_rs);
 751		skb_put(skb2, len + hlen);
 752		skb_reset_network_header(skb2);
 753		skb2->transport_header = skb2->network_header + hlen;
 754
 755		/*
 756		 *	Charge the memory for the fragment to any owner
 757		 *	it might possess
 758		 */
 759
 760		if (skb->sk)
 761			skb_set_owner_w(skb2, skb->sk);
 762
 763		/*
 764		 *	Copy the packet header into the new buffer.
 765		 */
 766
 767		skb_copy_from_linear_data(skb, skb_network_header(skb2), hlen);
 768
 769		/*
 770		 *	Copy a block of the IP datagram.
 771		 */
 772		if (skb_copy_bits(skb, ptr, skb_transport_header(skb2), len))
 773			BUG();
 774		left -= len;
 775
 776		/*
 777		 *	Fill in the new header fields.
 778		 */
 779		iph = ip_hdr(skb2);
 780		iph->frag_off = htons((offset >> 3));
 781
 782		if (IPCB(skb)->flags & IPSKB_FRAG_PMTU)
 783			iph->frag_off |= htons(IP_DF);
 784
 785		/* ANK: dirty, but effective trick. Upgrade options only if
 786		 * the segment to be fragmented was THE FIRST (otherwise,
 787		 * options are already fixed) and make it ONCE
 788		 * on the initial skb, so that all the following fragments
 789		 * will inherit fixed options.
 790		 */
 791		if (offset == 0)
 792			ip_options_fragment(skb);
 793
 794		/*
 795		 *	Added AC : If we are fragmenting a fragment that's not the
 796		 *		   last fragment then keep MF on each bit
 797		 */
 798		if (left > 0 || not_last_frag)
 799			iph->frag_off |= htons(IP_MF);
 800		ptr += len;
 801		offset += len;
 802
 803		/*
 804		 *	Put this fragment into the sending queue.
 805		 */
 806		iph->tot_len = htons(len + hlen);
 807
 808		ip_send_check(iph);
 809
 810		err = output(net, sk, skb2);
 811		if (err)
 812			goto fail;
 813
 814		IP_INC_STATS(net, IPSTATS_MIB_FRAGCREATES);
 815	}
 816	consume_skb(skb);
 817	IP_INC_STATS(net, IPSTATS_MIB_FRAGOKS);
 818	return err;
 819
 820fail:
 821	kfree_skb(skb);
 822	IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
 823	return err;
 824}
 825EXPORT_SYMBOL(ip_do_fragment);
 826
 827int
 828ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
 829{
 830	struct msghdr *msg = from;
 831
 832	if (skb->ip_summed == CHECKSUM_PARTIAL) {
 833		if (!copy_from_iter_full(to, len, &msg->msg_iter))
 834			return -EFAULT;
 835	} else {
 836		__wsum csum = 0;
 837		if (!csum_and_copy_from_iter_full(to, len, &csum, &msg->msg_iter))
 838			return -EFAULT;
 839		skb->csum = csum_block_add(skb->csum, csum, odd);
 840	}
 841	return 0;
 842}
 843EXPORT_SYMBOL(ip_generic_getfrag);
 844
 845static inline __wsum
 846csum_page(struct page *page, int offset, int copy)
 847{
 848	char *kaddr;
 849	__wsum csum;
 850	kaddr = kmap(page);
 851	csum = csum_partial(kaddr + offset, copy, 0);
 852	kunmap(page);
 853	return csum;
 854}
 855
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 856static int __ip_append_data(struct sock *sk,
 857			    struct flowi4 *fl4,
 858			    struct sk_buff_head *queue,
 859			    struct inet_cork *cork,
 860			    struct page_frag *pfrag,
 861			    int getfrag(void *from, char *to, int offset,
 862					int len, int odd, struct sk_buff *skb),
 863			    void *from, int length, int transhdrlen,
 864			    unsigned int flags)
 865{
 866	struct inet_sock *inet = inet_sk(sk);
 867	struct sk_buff *skb;
 868
 869	struct ip_options *opt = cork->opt;
 870	int hh_len;
 871	int exthdrlen;
 872	int mtu;
 873	int copy;
 874	int err;
 875	int offset = 0;
 876	unsigned int maxfraglen, fragheaderlen, maxnonfragsize;
 877	int csummode = CHECKSUM_NONE;
 878	struct rtable *rt = (struct rtable *)cork->dst;
 879	unsigned int wmem_alloc_delta = 0;
 880	u32 tskey = 0;
 881
 882	skb = skb_peek_tail(queue);
 883
 884	exthdrlen = !skb ? rt->dst.header_len : 0;
 885	mtu = cork->fragsize;
 886	if (cork->tx_flags & SKBTX_ANY_SW_TSTAMP &&
 887	    sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID)
 888		tskey = sk->sk_tskey++;
 889
 890	hh_len = LL_RESERVED_SPACE(rt->dst.dev);
 891
 892	fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
 893	maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
 894	maxnonfragsize = ip_sk_ignore_df(sk) ? 0xFFFF : mtu;
 895
 896	if (cork->length + length > maxnonfragsize - fragheaderlen) {
 897		ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
 898			       mtu - (opt ? opt->optlen : 0));
 899		return -EMSGSIZE;
 900	}
 901
 902	/*
 903	 * transhdrlen > 0 means that this is the first fragment and we wish
 904	 * it won't be fragmented in the future.
 905	 */
 906	if (transhdrlen &&
 907	    length + fragheaderlen <= mtu &&
 908	    rt->dst.dev->features & (NETIF_F_HW_CSUM | NETIF_F_IP_CSUM) &&
 909	    !(flags & MSG_MORE) &&
 910	    !exthdrlen)
 911		csummode = CHECKSUM_PARTIAL;
 912
 913	cork->length += length;
 
 
 
 
 
 
 
 
 
 
 
 914
 915	/* So, what's going on in the loop below?
 916	 *
 917	 * We use calculated fragment length to generate chained skb,
 918	 * each of segments is IP fragment ready for sending to network after
 919	 * adding appropriate IP header.
 920	 */
 921
 922	if (!skb)
 923		goto alloc_new_skb;
 924
 925	while (length > 0) {
 926		/* Check if the remaining data fits into current packet. */
 927		copy = mtu - skb->len;
 928		if (copy < length)
 929			copy = maxfraglen - skb->len;
 930		if (copy <= 0) {
 931			char *data;
 932			unsigned int datalen;
 933			unsigned int fraglen;
 934			unsigned int fraggap;
 935			unsigned int alloclen;
 936			struct sk_buff *skb_prev;
 937alloc_new_skb:
 938			skb_prev = skb;
 939			if (skb_prev)
 940				fraggap = skb_prev->len - maxfraglen;
 941			else
 942				fraggap = 0;
 943
 944			/*
 945			 * If remaining data exceeds the mtu,
 946			 * we know we need more fragment(s).
 947			 */
 948			datalen = length + fraggap;
 949			if (datalen > mtu - fragheaderlen)
 950				datalen = maxfraglen - fragheaderlen;
 951			fraglen = datalen + fragheaderlen;
 952
 953			if ((flags & MSG_MORE) &&
 954			    !(rt->dst.dev->features&NETIF_F_SG))
 955				alloclen = mtu;
 956			else
 957				alloclen = fraglen;
 958
 959			alloclen += exthdrlen;
 960
 961			/* The last fragment gets additional space at tail.
 962			 * Note, with MSG_MORE we overallocate on fragments,
 963			 * because we have no idea what fragment will be
 964			 * the last.
 965			 */
 966			if (datalen == length + fraggap)
 967				alloclen += rt->dst.trailer_len;
 968
 969			if (transhdrlen) {
 970				skb = sock_alloc_send_skb(sk,
 971						alloclen + hh_len + 15,
 972						(flags & MSG_DONTWAIT), &err);
 973			} else {
 974				skb = NULL;
 975				if (refcount_read(&sk->sk_wmem_alloc) + wmem_alloc_delta <=
 976				    2 * sk->sk_sndbuf)
 977					skb = alloc_skb(alloclen + hh_len + 15,
 978							sk->sk_allocation);
 
 979				if (unlikely(!skb))
 980					err = -ENOBUFS;
 981			}
 982			if (!skb)
 983				goto error;
 984
 985			/*
 986			 *	Fill in the control structures
 987			 */
 988			skb->ip_summed = csummode;
 989			skb->csum = 0;
 990			skb_reserve(skb, hh_len);
 991
 992			/* only the initial fragment is time stamped */
 993			skb_shinfo(skb)->tx_flags = cork->tx_flags;
 994			cork->tx_flags = 0;
 995			skb_shinfo(skb)->tskey = tskey;
 996			tskey = 0;
 997
 998			/*
 999			 *	Find where to start putting bytes.
1000			 */
1001			data = skb_put(skb, fraglen + exthdrlen);
1002			skb_set_network_header(skb, exthdrlen);
1003			skb->transport_header = (skb->network_header +
1004						 fragheaderlen);
1005			data += fragheaderlen + exthdrlen;
1006
1007			if (fraggap) {
1008				skb->csum = skb_copy_and_csum_bits(
1009					skb_prev, maxfraglen,
1010					data + transhdrlen, fraggap, 0);
1011				skb_prev->csum = csum_sub(skb_prev->csum,
1012							  skb->csum);
1013				data += fraggap;
1014				pskb_trim_unique(skb_prev, maxfraglen);
1015			}
1016
1017			copy = datalen - transhdrlen - fraggap;
1018			if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) {
1019				err = -EFAULT;
1020				kfree_skb(skb);
1021				goto error;
1022			}
1023
1024			offset += copy;
1025			length -= datalen - fraggap;
1026			transhdrlen = 0;
1027			exthdrlen = 0;
1028			csummode = CHECKSUM_NONE;
1029
1030			if ((flags & MSG_CONFIRM) && !skb_prev)
1031				skb_set_dst_pending_confirm(skb, 1);
1032
1033			/*
1034			 * Put the packet on the pending queue.
1035			 */
1036			if (!skb->destructor) {
1037				skb->destructor = sock_wfree;
1038				skb->sk = sk;
1039				wmem_alloc_delta += skb->truesize;
1040			}
1041			__skb_queue_tail(queue, skb);
1042			continue;
1043		}
1044
1045		if (copy > length)
1046			copy = length;
1047
1048		if (!(rt->dst.dev->features&NETIF_F_SG) &&
1049		    skb_tailroom(skb) >= copy) {
1050			unsigned int off;
1051
1052			off = skb->len;
1053			if (getfrag(from, skb_put(skb, copy),
1054					offset, copy, off, skb) < 0) {
1055				__skb_trim(skb, off);
1056				err = -EFAULT;
1057				goto error;
1058			}
1059		} else {
1060			int i = skb_shinfo(skb)->nr_frags;
1061
1062			err = -ENOMEM;
1063			if (!sk_page_frag_refill(sk, pfrag))
1064				goto error;
1065
1066			if (!skb_can_coalesce(skb, i, pfrag->page,
1067					      pfrag->offset)) {
1068				err = -EMSGSIZE;
1069				if (i == MAX_SKB_FRAGS)
1070					goto error;
1071
1072				__skb_fill_page_desc(skb, i, pfrag->page,
1073						     pfrag->offset, 0);
1074				skb_shinfo(skb)->nr_frags = ++i;
1075				get_page(pfrag->page);
1076			}
1077			copy = min_t(int, copy, pfrag->size - pfrag->offset);
1078			if (getfrag(from,
1079				    page_address(pfrag->page) + pfrag->offset,
1080				    offset, copy, skb->len, skb) < 0)
1081				goto error_efault;
1082
1083			pfrag->offset += copy;
1084			skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
1085			skb->len += copy;
1086			skb->data_len += copy;
1087			skb->truesize += copy;
1088			wmem_alloc_delta += copy;
1089		}
1090		offset += copy;
1091		length -= copy;
1092	}
1093
1094	if (wmem_alloc_delta)
1095		refcount_add(wmem_alloc_delta, &sk->sk_wmem_alloc);
1096	return 0;
1097
1098error_efault:
1099	err = -EFAULT;
1100error:
1101	cork->length -= length;
1102	IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1103	refcount_add(wmem_alloc_delta, &sk->sk_wmem_alloc);
1104	return err;
1105}
1106
1107static int ip_setup_cork(struct sock *sk, struct inet_cork *cork,
1108			 struct ipcm_cookie *ipc, struct rtable **rtp)
1109{
1110	struct ip_options_rcu *opt;
1111	struct rtable *rt;
1112
1113	rt = *rtp;
1114	if (unlikely(!rt))
1115		return -EFAULT;
1116
1117	/*
1118	 * setup for corking.
1119	 */
1120	opt = ipc->opt;
1121	if (opt) {
1122		if (!cork->opt) {
1123			cork->opt = kmalloc(sizeof(struct ip_options) + 40,
1124					    sk->sk_allocation);
1125			if (unlikely(!cork->opt))
1126				return -ENOBUFS;
1127		}
1128		memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen);
1129		cork->flags |= IPCORK_OPT;
1130		cork->addr = ipc->addr;
1131	}
1132
 
 
1133	/*
1134	 * We steal reference to this route, caller should not release it
1135	 */
1136	*rtp = NULL;
1137	cork->fragsize = ip_sk_use_pmtu(sk) ?
1138			 dst_mtu(&rt->dst) : rt->dst.dev->mtu;
1139	cork->dst = &rt->dst;
1140	cork->length = 0;
1141	cork->ttl = ipc->ttl;
1142	cork->tos = ipc->tos;
1143	cork->priority = ipc->priority;
1144	cork->tx_flags = ipc->tx_flags;
1145
1146	return 0;
1147}
1148
1149/*
1150 *	ip_append_data() and ip_append_page() can make one large IP datagram
1151 *	from many pieces of data. Each pieces will be holded on the socket
1152 *	until ip_push_pending_frames() is called. Each piece can be a page
1153 *	or non-page data.
1154 *
1155 *	Not only UDP, other transport protocols - e.g. raw sockets - can use
1156 *	this interface potentially.
1157 *
1158 *	LATER: length must be adjusted by pad at tail, when it is required.
1159 */
1160int ip_append_data(struct sock *sk, struct flowi4 *fl4,
1161		   int getfrag(void *from, char *to, int offset, int len,
1162			       int odd, struct sk_buff *skb),
1163		   void *from, int length, int transhdrlen,
1164		   struct ipcm_cookie *ipc, struct rtable **rtp,
1165		   unsigned int flags)
1166{
1167	struct inet_sock *inet = inet_sk(sk);
1168	int err;
1169
1170	if (flags&MSG_PROBE)
1171		return 0;
1172
1173	if (skb_queue_empty(&sk->sk_write_queue)) {
1174		err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp);
1175		if (err)
1176			return err;
1177	} else {
1178		transhdrlen = 0;
1179	}
1180
1181	return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base,
1182				sk_page_frag(sk), getfrag,
1183				from, length, transhdrlen, flags);
1184}
1185
1186ssize_t	ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page,
1187		       int offset, size_t size, int flags)
1188{
1189	struct inet_sock *inet = inet_sk(sk);
1190	struct sk_buff *skb;
1191	struct rtable *rt;
1192	struct ip_options *opt = NULL;
1193	struct inet_cork *cork;
1194	int hh_len;
1195	int mtu;
1196	int len;
1197	int err;
1198	unsigned int maxfraglen, fragheaderlen, fraggap, maxnonfragsize;
1199
1200	if (inet->hdrincl)
1201		return -EPERM;
1202
1203	if (flags&MSG_PROBE)
1204		return 0;
1205
1206	if (skb_queue_empty(&sk->sk_write_queue))
1207		return -EINVAL;
1208
1209	cork = &inet->cork.base;
1210	rt = (struct rtable *)cork->dst;
1211	if (cork->flags & IPCORK_OPT)
1212		opt = cork->opt;
1213
1214	if (!(rt->dst.dev->features&NETIF_F_SG))
1215		return -EOPNOTSUPP;
1216
1217	hh_len = LL_RESERVED_SPACE(rt->dst.dev);
1218	mtu = cork->fragsize;
1219
1220	fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
1221	maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
1222	maxnonfragsize = ip_sk_ignore_df(sk) ? 0xFFFF : mtu;
1223
1224	if (cork->length + size > maxnonfragsize - fragheaderlen) {
1225		ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
1226			       mtu - (opt ? opt->optlen : 0));
1227		return -EMSGSIZE;
1228	}
1229
1230	skb = skb_peek_tail(&sk->sk_write_queue);
1231	if (!skb)
1232		return -EINVAL;
1233
 
 
 
 
 
 
 
 
 
1234	cork->length += size;
1235
1236	while (size > 0) {
1237		/* Check if the remaining data fits into current packet. */
1238		len = mtu - skb->len;
1239		if (len < size)
1240			len = maxfraglen - skb->len;
1241
 
 
 
 
 
1242		if (len <= 0) {
1243			struct sk_buff *skb_prev;
1244			int alloclen;
1245
1246			skb_prev = skb;
1247			fraggap = skb_prev->len - maxfraglen;
1248
1249			alloclen = fragheaderlen + hh_len + fraggap + 15;
1250			skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation);
1251			if (unlikely(!skb)) {
1252				err = -ENOBUFS;
1253				goto error;
1254			}
1255
1256			/*
1257			 *	Fill in the control structures
1258			 */
1259			skb->ip_summed = CHECKSUM_NONE;
1260			skb->csum = 0;
1261			skb_reserve(skb, hh_len);
1262
1263			/*
1264			 *	Find where to start putting bytes.
1265			 */
1266			skb_put(skb, fragheaderlen + fraggap);
1267			skb_reset_network_header(skb);
1268			skb->transport_header = (skb->network_header +
1269						 fragheaderlen);
1270			if (fraggap) {
1271				skb->csum = skb_copy_and_csum_bits(skb_prev,
1272								   maxfraglen,
1273						    skb_transport_header(skb),
1274								   fraggap, 0);
1275				skb_prev->csum = csum_sub(skb_prev->csum,
1276							  skb->csum);
1277				pskb_trim_unique(skb_prev, maxfraglen);
1278			}
1279
1280			/*
1281			 * Put the packet on the pending queue.
1282			 */
1283			__skb_queue_tail(&sk->sk_write_queue, skb);
1284			continue;
1285		}
1286
1287		if (len > size)
1288			len = size;
1289
1290		if (skb_append_pagefrags(skb, page, offset, len)) {
1291			err = -EMSGSIZE;
1292			goto error;
1293		}
1294
1295		if (skb->ip_summed == CHECKSUM_NONE) {
1296			__wsum csum;
1297			csum = csum_page(page, offset, len);
1298			skb->csum = csum_block_add(skb->csum, csum, skb->len);
1299		}
1300
1301		skb->len += len;
1302		skb->data_len += len;
1303		skb->truesize += len;
1304		refcount_add(len, &sk->sk_wmem_alloc);
1305		offset += len;
1306		size -= len;
1307	}
1308	return 0;
1309
1310error:
1311	cork->length -= size;
1312	IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1313	return err;
1314}
1315
1316static void ip_cork_release(struct inet_cork *cork)
1317{
1318	cork->flags &= ~IPCORK_OPT;
1319	kfree(cork->opt);
1320	cork->opt = NULL;
1321	dst_release(cork->dst);
1322	cork->dst = NULL;
1323}
1324
1325/*
1326 *	Combined all pending IP fragments on the socket as one IP datagram
1327 *	and push them out.
1328 */
1329struct sk_buff *__ip_make_skb(struct sock *sk,
1330			      struct flowi4 *fl4,
1331			      struct sk_buff_head *queue,
1332			      struct inet_cork *cork)
1333{
1334	struct sk_buff *skb, *tmp_skb;
1335	struct sk_buff **tail_skb;
1336	struct inet_sock *inet = inet_sk(sk);
1337	struct net *net = sock_net(sk);
1338	struct ip_options *opt = NULL;
1339	struct rtable *rt = (struct rtable *)cork->dst;
1340	struct iphdr *iph;
1341	__be16 df = 0;
1342	__u8 ttl;
1343
1344	skb = __skb_dequeue(queue);
1345	if (!skb)
1346		goto out;
1347	tail_skb = &(skb_shinfo(skb)->frag_list);
1348
1349	/* move skb->data to ip header from ext header */
1350	if (skb->data < skb_network_header(skb))
1351		__skb_pull(skb, skb_network_offset(skb));
1352	while ((tmp_skb = __skb_dequeue(queue)) != NULL) {
1353		__skb_pull(tmp_skb, skb_network_header_len(skb));
1354		*tail_skb = tmp_skb;
1355		tail_skb = &(tmp_skb->next);
1356		skb->len += tmp_skb->len;
1357		skb->data_len += tmp_skb->len;
1358		skb->truesize += tmp_skb->truesize;
1359		tmp_skb->destructor = NULL;
1360		tmp_skb->sk = NULL;
1361	}
1362
1363	/* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow
1364	 * to fragment the frame generated here. No matter, what transforms
1365	 * how transforms change size of the packet, it will come out.
1366	 */
1367	skb->ignore_df = ip_sk_ignore_df(sk);
1368
1369	/* DF bit is set when we want to see DF on outgoing frames.
1370	 * If ignore_df is set too, we still allow to fragment this frame
1371	 * locally. */
1372	if (inet->pmtudisc == IP_PMTUDISC_DO ||
1373	    inet->pmtudisc == IP_PMTUDISC_PROBE ||
1374	    (skb->len <= dst_mtu(&rt->dst) &&
1375	     ip_dont_fragment(sk, &rt->dst)))
1376		df = htons(IP_DF);
1377
1378	if (cork->flags & IPCORK_OPT)
1379		opt = cork->opt;
1380
1381	if (cork->ttl != 0)
1382		ttl = cork->ttl;
1383	else if (rt->rt_type == RTN_MULTICAST)
1384		ttl = inet->mc_ttl;
1385	else
1386		ttl = ip_select_ttl(inet, &rt->dst);
1387
1388	iph = ip_hdr(skb);
1389	iph->version = 4;
1390	iph->ihl = 5;
1391	iph->tos = (cork->tos != -1) ? cork->tos : inet->tos;
1392	iph->frag_off = df;
1393	iph->ttl = ttl;
1394	iph->protocol = sk->sk_protocol;
1395	ip_copy_addrs(iph, fl4);
1396	ip_select_ident(net, skb, sk);
1397
1398	if (opt) {
1399		iph->ihl += opt->optlen>>2;
1400		ip_options_build(skb, opt, cork->addr, rt, 0);
1401	}
1402
1403	skb->priority = (cork->tos != -1) ? cork->priority: sk->sk_priority;
1404	skb->mark = sk->sk_mark;
1405	/*
1406	 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec
1407	 * on dst refcount
1408	 */
1409	cork->dst = NULL;
1410	skb_dst_set(skb, &rt->dst);
1411
1412	if (iph->protocol == IPPROTO_ICMP)
1413		icmp_out_count(net, ((struct icmphdr *)
1414			skb_transport_header(skb))->type);
1415
1416	ip_cork_release(cork);
1417out:
1418	return skb;
1419}
1420
1421int ip_send_skb(struct net *net, struct sk_buff *skb)
1422{
1423	int err;
1424
1425	err = ip_local_out(net, skb->sk, skb);
1426	if (err) {
1427		if (err > 0)
1428			err = net_xmit_errno(err);
1429		if (err)
1430			IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS);
1431	}
1432
1433	return err;
1434}
1435
1436int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4)
1437{
1438	struct sk_buff *skb;
1439
1440	skb = ip_finish_skb(sk, fl4);
1441	if (!skb)
1442		return 0;
1443
1444	/* Netfilter gets whole the not fragmented skb. */
1445	return ip_send_skb(sock_net(sk), skb);
1446}
1447
1448/*
1449 *	Throw away all pending data on the socket.
1450 */
1451static void __ip_flush_pending_frames(struct sock *sk,
1452				      struct sk_buff_head *queue,
1453				      struct inet_cork *cork)
1454{
1455	struct sk_buff *skb;
1456
1457	while ((skb = __skb_dequeue_tail(queue)) != NULL)
1458		kfree_skb(skb);
1459
1460	ip_cork_release(cork);
1461}
1462
1463void ip_flush_pending_frames(struct sock *sk)
1464{
1465	__ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork.base);
1466}
1467
1468struct sk_buff *ip_make_skb(struct sock *sk,
1469			    struct flowi4 *fl4,
1470			    int getfrag(void *from, char *to, int offset,
1471					int len, int odd, struct sk_buff *skb),
1472			    void *from, int length, int transhdrlen,
1473			    struct ipcm_cookie *ipc, struct rtable **rtp,
1474			    unsigned int flags)
1475{
1476	struct inet_cork cork;
1477	struct sk_buff_head queue;
1478	int err;
1479
1480	if (flags & MSG_PROBE)
1481		return NULL;
1482
1483	__skb_queue_head_init(&queue);
1484
1485	cork.flags = 0;
1486	cork.addr = 0;
1487	cork.opt = NULL;
1488	err = ip_setup_cork(sk, &cork, ipc, rtp);
1489	if (err)
1490		return ERR_PTR(err);
1491
1492	err = __ip_append_data(sk, fl4, &queue, &cork,
1493			       &current->task_frag, getfrag,
1494			       from, length, transhdrlen, flags);
1495	if (err) {
1496		__ip_flush_pending_frames(sk, &queue, &cork);
1497		return ERR_PTR(err);
1498	}
1499
1500	return __ip_make_skb(sk, fl4, &queue, &cork);
1501}
1502
1503/*
1504 *	Fetch data from kernel space and fill in checksum if needed.
1505 */
1506static int ip_reply_glue_bits(void *dptr, char *to, int offset,
1507			      int len, int odd, struct sk_buff *skb)
1508{
1509	__wsum csum;
1510
1511	csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0);
1512	skb->csum = csum_block_add(skb->csum, csum, odd);
1513	return 0;
1514}
1515
1516/*
1517 *	Generic function to send a packet as reply to another packet.
1518 *	Used to send some TCP resets/acks so far.
1519 */
1520void ip_send_unicast_reply(struct sock *sk, struct sk_buff *skb,
1521			   const struct ip_options *sopt,
1522			   __be32 daddr, __be32 saddr,
1523			   const struct ip_reply_arg *arg,
1524			   unsigned int len)
1525{
1526	struct ip_options_data replyopts;
1527	struct ipcm_cookie ipc;
1528	struct flowi4 fl4;
1529	struct rtable *rt = skb_rtable(skb);
1530	struct net *net = sock_net(sk);
1531	struct sk_buff *nskb;
1532	int err;
1533	int oif;
1534
1535	if (__ip_options_echo(net, &replyopts.opt.opt, skb, sopt))
1536		return;
1537
1538	ipc.addr = daddr;
1539	ipc.opt = NULL;
1540	ipc.tx_flags = 0;
1541	ipc.ttl = 0;
1542	ipc.tos = -1;
1543
1544	if (replyopts.opt.opt.optlen) {
1545		ipc.opt = &replyopts.opt;
1546
1547		if (replyopts.opt.opt.srr)
1548			daddr = replyopts.opt.opt.faddr;
1549	}
1550
1551	oif = arg->bound_dev_if;
1552	if (!oif && netif_index_is_l3_master(net, skb->skb_iif))
1553		oif = skb->skb_iif;
1554
1555	flowi4_init_output(&fl4, oif,
1556			   IP4_REPLY_MARK(net, skb->mark),
1557			   RT_TOS(arg->tos),
1558			   RT_SCOPE_UNIVERSE, ip_hdr(skb)->protocol,
1559			   ip_reply_arg_flowi_flags(arg),
1560			   daddr, saddr,
1561			   tcp_hdr(skb)->source, tcp_hdr(skb)->dest,
1562			   arg->uid);
1563	security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
1564	rt = ip_route_output_key(net, &fl4);
1565	if (IS_ERR(rt))
1566		return;
1567
1568	inet_sk(sk)->tos = arg->tos;
1569
1570	sk->sk_priority = skb->priority;
1571	sk->sk_protocol = ip_hdr(skb)->protocol;
1572	sk->sk_bound_dev_if = arg->bound_dev_if;
1573	sk->sk_sndbuf = sysctl_wmem_default;
1574	sk->sk_mark = fl4.flowi4_mark;
1575	err = ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base,
1576			     len, 0, &ipc, &rt, MSG_DONTWAIT);
1577	if (unlikely(err)) {
1578		ip_flush_pending_frames(sk);
1579		goto out;
1580	}
1581
1582	nskb = skb_peek(&sk->sk_write_queue);
1583	if (nskb) {
1584		if (arg->csumoffset >= 0)
1585			*((__sum16 *)skb_transport_header(nskb) +
1586			  arg->csumoffset) = csum_fold(csum_add(nskb->csum,
1587								arg->csum));
1588		nskb->ip_summed = CHECKSUM_NONE;
1589		ip_push_pending_frames(sk, &fl4);
1590	}
1591out:
1592	ip_rt_put(rt);
1593}
1594
1595void __init ip_init(void)
1596{
1597	ip_rt_init();
1598	inet_initpeers();
1599
1600#if defined(CONFIG_IP_MULTICAST)
1601	igmp_mc_init();
1602#endif
1603}