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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 readability.
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/gso.h>
77#include <net/inetpeer.h>
78#include <net/inet_ecn.h>
79#include <net/lwtunnel.h>
80#include <net/inet_dscp.h>
81#include <linux/bpf-cgroup.h>
82#include <linux/igmp.h>
83#include <linux/netfilter_ipv4.h>
84#include <linux/netfilter_bridge.h>
85#include <linux/netlink.h>
86#include <linux/tcp.h>
87
88static int
89ip_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
90 unsigned int mtu,
91 int (*output)(struct net *, struct sock *, struct sk_buff *));
92
93/* Generate a checksum for an outgoing IP datagram. */
94void ip_send_check(struct iphdr *iph)
95{
96 iph->check = 0;
97 iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
98}
99EXPORT_SYMBOL(ip_send_check);
100
101int __ip_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
102{
103 struct iphdr *iph = ip_hdr(skb);
104
105 IP_INC_STATS(net, IPSTATS_MIB_OUTREQUESTS);
106
107 iph_set_totlen(iph, skb->len);
108 ip_send_check(iph);
109
110 /* if egress device is enslaved to an L3 master device pass the
111 * skb to its handler for processing
112 */
113 skb = l3mdev_ip_out(sk, skb);
114 if (unlikely(!skb))
115 return 0;
116
117 skb->protocol = htons(ETH_P_IP);
118
119 return nf_hook(NFPROTO_IPV4, NF_INET_LOCAL_OUT,
120 net, sk, skb, NULL, skb_dst(skb)->dev,
121 dst_output);
122}
123
124int ip_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
125{
126 int err;
127
128 err = __ip_local_out(net, sk, skb);
129 if (likely(err == 1))
130 err = dst_output(net, sk, skb);
131
132 return err;
133}
134EXPORT_SYMBOL_GPL(ip_local_out);
135
136static inline int ip_select_ttl(const struct inet_sock *inet,
137 const struct dst_entry *dst)
138{
139 int ttl = READ_ONCE(inet->uc_ttl);
140
141 if (ttl < 0)
142 ttl = ip4_dst_hoplimit(dst);
143 return ttl;
144}
145
146/*
147 * Add an ip header to a skbuff and send it out.
148 *
149 */
150int ip_build_and_send_pkt(struct sk_buff *skb, const struct sock *sk,
151 __be32 saddr, __be32 daddr, struct ip_options_rcu *opt,
152 u8 tos)
153{
154 const struct inet_sock *inet = inet_sk(sk);
155 struct rtable *rt = skb_rtable(skb);
156 struct net *net = sock_net(sk);
157 struct iphdr *iph;
158
159 /* Build the IP header. */
160 skb_push(skb, sizeof(struct iphdr) + (opt ? opt->opt.optlen : 0));
161 skb_reset_network_header(skb);
162 iph = ip_hdr(skb);
163 iph->version = 4;
164 iph->ihl = 5;
165 iph->tos = tos;
166 iph->ttl = ip_select_ttl(inet, &rt->dst);
167 iph->daddr = (opt && opt->opt.srr ? opt->opt.faddr : daddr);
168 iph->saddr = saddr;
169 iph->protocol = sk->sk_protocol;
170 /* Do not bother generating IPID for small packets (eg SYNACK) */
171 if (skb->len <= IPV4_MIN_MTU || ip_dont_fragment(sk, &rt->dst)) {
172 iph->frag_off = htons(IP_DF);
173 iph->id = 0;
174 } else {
175 iph->frag_off = 0;
176 /* TCP packets here are SYNACK with fat IPv4/TCP options.
177 * Avoid using the hashed IP ident generator.
178 */
179 if (sk->sk_protocol == IPPROTO_TCP)
180 iph->id = (__force __be16)get_random_u16();
181 else
182 __ip_select_ident(net, iph, 1);
183 }
184
185 if (opt && opt->opt.optlen) {
186 iph->ihl += opt->opt.optlen>>2;
187 ip_options_build(skb, &opt->opt, daddr, rt);
188 }
189
190 skb->priority = READ_ONCE(sk->sk_priority);
191 if (!skb->mark)
192 skb->mark = READ_ONCE(sk->sk_mark);
193
194 /* Send it out. */
195 return ip_local_out(net, skb->sk, skb);
196}
197EXPORT_SYMBOL_GPL(ip_build_and_send_pkt);
198
199static int ip_finish_output2(struct net *net, struct sock *sk, struct sk_buff *skb)
200{
201 struct dst_entry *dst = skb_dst(skb);
202 struct rtable *rt = dst_rtable(dst);
203 struct net_device *dev = dst->dev;
204 unsigned int hh_len = LL_RESERVED_SPACE(dev);
205 struct neighbour *neigh;
206 bool is_v6gw = false;
207
208 if (rt->rt_type == RTN_MULTICAST) {
209 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUTMCAST, skb->len);
210 } else if (rt->rt_type == RTN_BROADCAST)
211 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUTBCAST, skb->len);
212
213 /* OUTOCTETS should be counted after fragment */
214 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUT, skb->len);
215
216 if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) {
217 skb = skb_expand_head(skb, hh_len);
218 if (!skb)
219 return -ENOMEM;
220 }
221
222 if (lwtunnel_xmit_redirect(dst->lwtstate)) {
223 int res = lwtunnel_xmit(skb);
224
225 if (res != LWTUNNEL_XMIT_CONTINUE)
226 return res;
227 }
228
229 rcu_read_lock();
230 neigh = ip_neigh_for_gw(rt, skb, &is_v6gw);
231 if (!IS_ERR(neigh)) {
232 int res;
233
234 sock_confirm_neigh(skb, neigh);
235 /* if crossing protocols, can not use the cached header */
236 res = neigh_output(neigh, skb, is_v6gw);
237 rcu_read_unlock();
238 return res;
239 }
240 rcu_read_unlock();
241
242 net_dbg_ratelimited("%s: No header cache and no neighbour!\n",
243 __func__);
244 kfree_skb_reason(skb, SKB_DROP_REASON_NEIGH_CREATEFAIL);
245 return PTR_ERR(neigh);
246}
247
248static int ip_finish_output_gso(struct net *net, struct sock *sk,
249 struct sk_buff *skb, unsigned int mtu)
250{
251 struct sk_buff *segs, *nskb;
252 netdev_features_t features;
253 int ret = 0;
254
255 /* common case: seglen is <= mtu
256 */
257 if (skb_gso_validate_network_len(skb, mtu))
258 return ip_finish_output2(net, sk, skb);
259
260 /* Slowpath - GSO segment length exceeds the egress MTU.
261 *
262 * This can happen in several cases:
263 * - Forwarding of a TCP GRO skb, when DF flag is not set.
264 * - Forwarding of an skb that arrived on a virtualization interface
265 * (virtio-net/vhost/tap) with TSO/GSO size set by other network
266 * stack.
267 * - Local GSO skb transmitted on an NETIF_F_TSO tunnel stacked over an
268 * interface with a smaller MTU.
269 * - Arriving GRO skb (or GSO skb in a virtualized environment) that is
270 * bridged to a NETIF_F_TSO tunnel stacked over an interface with an
271 * insufficient MTU.
272 */
273 features = netif_skb_features(skb);
274 BUILD_BUG_ON(sizeof(*IPCB(skb)) > SKB_GSO_CB_OFFSET);
275 segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK);
276 if (IS_ERR_OR_NULL(segs)) {
277 kfree_skb(skb);
278 return -ENOMEM;
279 }
280
281 consume_skb(skb);
282
283 skb_list_walk_safe(segs, segs, nskb) {
284 int err;
285
286 skb_mark_not_on_list(segs);
287 err = ip_fragment(net, sk, segs, mtu, ip_finish_output2);
288
289 if (err && ret == 0)
290 ret = err;
291 }
292
293 return ret;
294}
295
296static int __ip_finish_output(struct net *net, struct sock *sk, struct sk_buff *skb)
297{
298 unsigned int mtu;
299
300#if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
301 /* Policy lookup after SNAT yielded a new policy */
302 if (skb_dst(skb)->xfrm) {
303 IPCB(skb)->flags |= IPSKB_REROUTED;
304 return dst_output(net, sk, skb);
305 }
306#endif
307 mtu = ip_skb_dst_mtu(sk, skb);
308 if (skb_is_gso(skb))
309 return ip_finish_output_gso(net, sk, skb, mtu);
310
311 if (skb->len > mtu || IPCB(skb)->frag_max_size)
312 return ip_fragment(net, sk, skb, mtu, ip_finish_output2);
313
314 return ip_finish_output2(net, sk, skb);
315}
316
317static int ip_finish_output(struct net *net, struct sock *sk, struct sk_buff *skb)
318{
319 int ret;
320
321 ret = BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb);
322 switch (ret) {
323 case NET_XMIT_SUCCESS:
324 return __ip_finish_output(net, sk, skb);
325 case NET_XMIT_CN:
326 return __ip_finish_output(net, sk, skb) ? : ret;
327 default:
328 kfree_skb_reason(skb, SKB_DROP_REASON_BPF_CGROUP_EGRESS);
329 return ret;
330 }
331}
332
333static int ip_mc_finish_output(struct net *net, struct sock *sk,
334 struct sk_buff *skb)
335{
336 struct rtable *new_rt;
337 bool do_cn = false;
338 int ret, err;
339
340 ret = BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb);
341 switch (ret) {
342 case NET_XMIT_CN:
343 do_cn = true;
344 fallthrough;
345 case NET_XMIT_SUCCESS:
346 break;
347 default:
348 kfree_skb_reason(skb, SKB_DROP_REASON_BPF_CGROUP_EGRESS);
349 return ret;
350 }
351
352 /* Reset rt_iif so that inet_iif() will return skb->skb_iif. Setting
353 * this to non-zero causes ipi_ifindex in in_pktinfo to be overwritten,
354 * see ipv4_pktinfo_prepare().
355 */
356 new_rt = rt_dst_clone(net->loopback_dev, skb_rtable(skb));
357 if (new_rt) {
358 new_rt->rt_iif = 0;
359 skb_dst_drop(skb);
360 skb_dst_set(skb, &new_rt->dst);
361 }
362
363 err = dev_loopback_xmit(net, sk, skb);
364 return (do_cn && err) ? ret : err;
365}
366
367int ip_mc_output(struct net *net, struct sock *sk, struct sk_buff *skb)
368{
369 struct rtable *rt = skb_rtable(skb);
370 struct net_device *dev = rt->dst.dev;
371
372 /*
373 * If the indicated interface is up and running, send the packet.
374 */
375 skb->dev = dev;
376 skb->protocol = htons(ETH_P_IP);
377
378 /*
379 * Multicasts are looped back for other local users
380 */
381
382 if (rt->rt_flags&RTCF_MULTICAST) {
383 if (sk_mc_loop(sk)
384#ifdef CONFIG_IP_MROUTE
385 /* Small optimization: do not loopback not local frames,
386 which returned after forwarding; they will be dropped
387 by ip_mr_input in any case.
388 Note, that local frames are looped back to be delivered
389 to local recipients.
390
391 This check is duplicated in ip_mr_input at the moment.
392 */
393 &&
394 ((rt->rt_flags & RTCF_LOCAL) ||
395 !(IPCB(skb)->flags & IPSKB_FORWARDED))
396#endif
397 ) {
398 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
399 if (newskb)
400 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
401 net, sk, newskb, NULL, newskb->dev,
402 ip_mc_finish_output);
403 }
404
405 /* Multicasts with ttl 0 must not go beyond the host */
406
407 if (ip_hdr(skb)->ttl == 0) {
408 kfree_skb(skb);
409 return 0;
410 }
411 }
412
413 if (rt->rt_flags&RTCF_BROADCAST) {
414 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
415 if (newskb)
416 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
417 net, sk, newskb, NULL, newskb->dev,
418 ip_mc_finish_output);
419 }
420
421 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
422 net, sk, skb, NULL, skb->dev,
423 ip_finish_output,
424 !(IPCB(skb)->flags & IPSKB_REROUTED));
425}
426
427int ip_output(struct net *net, struct sock *sk, struct sk_buff *skb)
428{
429 struct net_device *dev = skb_dst(skb)->dev, *indev = skb->dev;
430
431 skb->dev = dev;
432 skb->protocol = htons(ETH_P_IP);
433
434 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
435 net, sk, skb, indev, dev,
436 ip_finish_output,
437 !(IPCB(skb)->flags & IPSKB_REROUTED));
438}
439EXPORT_SYMBOL(ip_output);
440
441/*
442 * copy saddr and daddr, possibly using 64bit load/stores
443 * Equivalent to :
444 * iph->saddr = fl4->saddr;
445 * iph->daddr = fl4->daddr;
446 */
447static void ip_copy_addrs(struct iphdr *iph, const struct flowi4 *fl4)
448{
449 BUILD_BUG_ON(offsetof(typeof(*fl4), daddr) !=
450 offsetof(typeof(*fl4), saddr) + sizeof(fl4->saddr));
451
452 iph->saddr = fl4->saddr;
453 iph->daddr = fl4->daddr;
454}
455
456/* Note: skb->sk can be different from sk, in case of tunnels */
457int __ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl,
458 __u8 tos)
459{
460 struct inet_sock *inet = inet_sk(sk);
461 struct net *net = sock_net(sk);
462 struct ip_options_rcu *inet_opt;
463 struct flowi4 *fl4;
464 struct rtable *rt;
465 struct iphdr *iph;
466 int res;
467
468 /* Skip all of this if the packet is already routed,
469 * f.e. by something like SCTP.
470 */
471 rcu_read_lock();
472 inet_opt = rcu_dereference(inet->inet_opt);
473 fl4 = &fl->u.ip4;
474 rt = skb_rtable(skb);
475 if (rt)
476 goto packet_routed;
477
478 /* Make sure we can route this packet. */
479 rt = dst_rtable(__sk_dst_check(sk, 0));
480 if (!rt) {
481 __be32 daddr;
482
483 /* Use correct destination address if we have options. */
484 daddr = inet->inet_daddr;
485 if (inet_opt && inet_opt->opt.srr)
486 daddr = inet_opt->opt.faddr;
487
488 /* If this fails, retransmit mechanism of transport layer will
489 * keep trying until route appears or the connection times
490 * itself out.
491 */
492 rt = ip_route_output_ports(net, fl4, sk,
493 daddr, inet->inet_saddr,
494 inet->inet_dport,
495 inet->inet_sport,
496 sk->sk_protocol,
497 tos & INET_DSCP_MASK,
498 sk->sk_bound_dev_if);
499 if (IS_ERR(rt))
500 goto no_route;
501 sk_setup_caps(sk, &rt->dst);
502 }
503 skb_dst_set_noref(skb, &rt->dst);
504
505packet_routed:
506 if (inet_opt && inet_opt->opt.is_strictroute && rt->rt_uses_gateway)
507 goto no_route;
508
509 /* OK, we know where to send it, allocate and build IP header. */
510 skb_push(skb, sizeof(struct iphdr) + (inet_opt ? inet_opt->opt.optlen : 0));
511 skb_reset_network_header(skb);
512 iph = ip_hdr(skb);
513 *((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (tos & 0xff));
514 if (ip_dont_fragment(sk, &rt->dst) && !skb->ignore_df)
515 iph->frag_off = htons(IP_DF);
516 else
517 iph->frag_off = 0;
518 iph->ttl = ip_select_ttl(inet, &rt->dst);
519 iph->protocol = sk->sk_protocol;
520 ip_copy_addrs(iph, fl4);
521
522 /* Transport layer set skb->h.foo itself. */
523
524 if (inet_opt && inet_opt->opt.optlen) {
525 iph->ihl += inet_opt->opt.optlen >> 2;
526 ip_options_build(skb, &inet_opt->opt, inet->inet_daddr, rt);
527 }
528
529 ip_select_ident_segs(net, skb, sk,
530 skb_shinfo(skb)->gso_segs ?: 1);
531
532 /* TODO : should we use skb->sk here instead of sk ? */
533 skb->priority = READ_ONCE(sk->sk_priority);
534 skb->mark = READ_ONCE(sk->sk_mark);
535
536 res = ip_local_out(net, sk, skb);
537 rcu_read_unlock();
538 return res;
539
540no_route:
541 rcu_read_unlock();
542 IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
543 kfree_skb_reason(skb, SKB_DROP_REASON_IP_OUTNOROUTES);
544 return -EHOSTUNREACH;
545}
546EXPORT_SYMBOL(__ip_queue_xmit);
547
548int ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl)
549{
550 return __ip_queue_xmit(sk, skb, fl, READ_ONCE(inet_sk(sk)->tos));
551}
552EXPORT_SYMBOL(ip_queue_xmit);
553
554static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from)
555{
556 to->pkt_type = from->pkt_type;
557 to->priority = from->priority;
558 to->protocol = from->protocol;
559 to->skb_iif = from->skb_iif;
560 skb_dst_drop(to);
561 skb_dst_copy(to, from);
562 to->dev = from->dev;
563 to->mark = from->mark;
564
565 skb_copy_hash(to, from);
566
567#ifdef CONFIG_NET_SCHED
568 to->tc_index = from->tc_index;
569#endif
570 nf_copy(to, from);
571 skb_ext_copy(to, from);
572#if IS_ENABLED(CONFIG_IP_VS)
573 to->ipvs_property = from->ipvs_property;
574#endif
575 skb_copy_secmark(to, from);
576}
577
578static int ip_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
579 unsigned int mtu,
580 int (*output)(struct net *, struct sock *, struct sk_buff *))
581{
582 struct iphdr *iph = ip_hdr(skb);
583
584 if ((iph->frag_off & htons(IP_DF)) == 0)
585 return ip_do_fragment(net, sk, skb, output);
586
587 if (unlikely(!skb->ignore_df ||
588 (IPCB(skb)->frag_max_size &&
589 IPCB(skb)->frag_max_size > mtu))) {
590 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
591 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
592 htonl(mtu));
593 kfree_skb(skb);
594 return -EMSGSIZE;
595 }
596
597 return ip_do_fragment(net, sk, skb, output);
598}
599
600void ip_fraglist_init(struct sk_buff *skb, struct iphdr *iph,
601 unsigned int hlen, struct ip_fraglist_iter *iter)
602{
603 unsigned int first_len = skb_pagelen(skb);
604
605 iter->frag = skb_shinfo(skb)->frag_list;
606 skb_frag_list_init(skb);
607
608 iter->offset = 0;
609 iter->iph = iph;
610 iter->hlen = hlen;
611
612 skb->data_len = first_len - skb_headlen(skb);
613 skb->len = first_len;
614 iph->tot_len = htons(first_len);
615 iph->frag_off = htons(IP_MF);
616 ip_send_check(iph);
617}
618EXPORT_SYMBOL(ip_fraglist_init);
619
620void ip_fraglist_prepare(struct sk_buff *skb, struct ip_fraglist_iter *iter)
621{
622 unsigned int hlen = iter->hlen;
623 struct iphdr *iph = iter->iph;
624 struct sk_buff *frag;
625
626 frag = iter->frag;
627 frag->ip_summed = CHECKSUM_NONE;
628 skb_reset_transport_header(frag);
629 __skb_push(frag, hlen);
630 skb_reset_network_header(frag);
631 memcpy(skb_network_header(frag), iph, hlen);
632 iter->iph = ip_hdr(frag);
633 iph = iter->iph;
634 iph->tot_len = htons(frag->len);
635 ip_copy_metadata(frag, skb);
636 iter->offset += skb->len - hlen;
637 iph->frag_off = htons(iter->offset >> 3);
638 if (frag->next)
639 iph->frag_off |= htons(IP_MF);
640 /* Ready, complete checksum */
641 ip_send_check(iph);
642}
643EXPORT_SYMBOL(ip_fraglist_prepare);
644
645void ip_frag_init(struct sk_buff *skb, unsigned int hlen,
646 unsigned int ll_rs, unsigned int mtu, bool DF,
647 struct ip_frag_state *state)
648{
649 struct iphdr *iph = ip_hdr(skb);
650
651 state->DF = DF;
652 state->hlen = hlen;
653 state->ll_rs = ll_rs;
654 state->mtu = mtu;
655
656 state->left = skb->len - hlen; /* Space per frame */
657 state->ptr = hlen; /* Where to start from */
658
659 state->offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3;
660 state->not_last_frag = iph->frag_off & htons(IP_MF);
661}
662EXPORT_SYMBOL(ip_frag_init);
663
664static void ip_frag_ipcb(struct sk_buff *from, struct sk_buff *to,
665 bool first_frag)
666{
667 /* Copy the flags to each fragment. */
668 IPCB(to)->flags = IPCB(from)->flags;
669
670 /* ANK: dirty, but effective trick. Upgrade options only if
671 * the segment to be fragmented was THE FIRST (otherwise,
672 * options are already fixed) and make it ONCE
673 * on the initial skb, so that all the following fragments
674 * will inherit fixed options.
675 */
676 if (first_frag)
677 ip_options_fragment(from);
678}
679
680struct sk_buff *ip_frag_next(struct sk_buff *skb, struct ip_frag_state *state)
681{
682 unsigned int len = state->left;
683 struct sk_buff *skb2;
684 struct iphdr *iph;
685
686 /* IF: it doesn't fit, use 'mtu' - the data space left */
687 if (len > state->mtu)
688 len = state->mtu;
689 /* IF: we are not sending up to and including the packet end
690 then align the next start on an eight byte boundary */
691 if (len < state->left) {
692 len &= ~7;
693 }
694
695 /* Allocate buffer */
696 skb2 = alloc_skb(len + state->hlen + state->ll_rs, GFP_ATOMIC);
697 if (!skb2)
698 return ERR_PTR(-ENOMEM);
699
700 /*
701 * Set up data on packet
702 */
703
704 ip_copy_metadata(skb2, skb);
705 skb_reserve(skb2, state->ll_rs);
706 skb_put(skb2, len + state->hlen);
707 skb_reset_network_header(skb2);
708 skb2->transport_header = skb2->network_header + state->hlen;
709
710 /*
711 * Charge the memory for the fragment to any owner
712 * it might possess
713 */
714
715 if (skb->sk)
716 skb_set_owner_w(skb2, skb->sk);
717
718 /*
719 * Copy the packet header into the new buffer.
720 */
721
722 skb_copy_from_linear_data(skb, skb_network_header(skb2), state->hlen);
723
724 /*
725 * Copy a block of the IP datagram.
726 */
727 if (skb_copy_bits(skb, state->ptr, skb_transport_header(skb2), len))
728 BUG();
729 state->left -= len;
730
731 /*
732 * Fill in the new header fields.
733 */
734 iph = ip_hdr(skb2);
735 iph->frag_off = htons((state->offset >> 3));
736 if (state->DF)
737 iph->frag_off |= htons(IP_DF);
738
739 /*
740 * Added AC : If we are fragmenting a fragment that's not the
741 * last fragment then keep MF on each bit
742 */
743 if (state->left > 0 || state->not_last_frag)
744 iph->frag_off |= htons(IP_MF);
745 state->ptr += len;
746 state->offset += len;
747
748 iph->tot_len = htons(len + state->hlen);
749
750 ip_send_check(iph);
751
752 return skb2;
753}
754EXPORT_SYMBOL(ip_frag_next);
755
756/*
757 * This IP datagram is too large to be sent in one piece. Break it up into
758 * smaller pieces (each of size equal to IP header plus
759 * a block of the data of the original IP data part) that will yet fit in a
760 * single device frame, and queue such a frame for sending.
761 */
762
763int ip_do_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
764 int (*output)(struct net *, struct sock *, struct sk_buff *))
765{
766 struct iphdr *iph;
767 struct sk_buff *skb2;
768 u8 tstamp_type = skb->tstamp_type;
769 struct rtable *rt = skb_rtable(skb);
770 unsigned int mtu, hlen, ll_rs;
771 struct ip_fraglist_iter iter;
772 ktime_t tstamp = skb->tstamp;
773 struct ip_frag_state state;
774 int err = 0;
775
776 /* for offloaded checksums cleanup checksum before fragmentation */
777 if (skb->ip_summed == CHECKSUM_PARTIAL &&
778 (err = skb_checksum_help(skb)))
779 goto fail;
780
781 /*
782 * Point into the IP datagram header.
783 */
784
785 iph = ip_hdr(skb);
786
787 mtu = ip_skb_dst_mtu(sk, skb);
788 if (IPCB(skb)->frag_max_size && IPCB(skb)->frag_max_size < mtu)
789 mtu = IPCB(skb)->frag_max_size;
790
791 /*
792 * Setup starting values.
793 */
794
795 hlen = iph->ihl * 4;
796 mtu = mtu - hlen; /* Size of data space */
797 IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE;
798 ll_rs = LL_RESERVED_SPACE(rt->dst.dev);
799
800 /* When frag_list is given, use it. First, check its validity:
801 * some transformers could create wrong frag_list or break existing
802 * one, it is not prohibited. In this case fall back to copying.
803 *
804 * LATER: this step can be merged to real generation of fragments,
805 * we can switch to copy when see the first bad fragment.
806 */
807 if (skb_has_frag_list(skb)) {
808 struct sk_buff *frag, *frag2;
809 unsigned int first_len = skb_pagelen(skb);
810
811 if (first_len - hlen > mtu ||
812 ((first_len - hlen) & 7) ||
813 ip_is_fragment(iph) ||
814 skb_cloned(skb) ||
815 skb_headroom(skb) < ll_rs)
816 goto slow_path;
817
818 skb_walk_frags(skb, frag) {
819 /* Correct geometry. */
820 if (frag->len > mtu ||
821 ((frag->len & 7) && frag->next) ||
822 skb_headroom(frag) < hlen + ll_rs)
823 goto slow_path_clean;
824
825 /* Partially cloned skb? */
826 if (skb_shared(frag))
827 goto slow_path_clean;
828
829 BUG_ON(frag->sk);
830 if (skb->sk) {
831 frag->sk = skb->sk;
832 frag->destructor = sock_wfree;
833 }
834 skb->truesize -= frag->truesize;
835 }
836
837 /* Everything is OK. Generate! */
838 ip_fraglist_init(skb, iph, hlen, &iter);
839
840 for (;;) {
841 /* Prepare header of the next frame,
842 * before previous one went down. */
843 if (iter.frag) {
844 bool first_frag = (iter.offset == 0);
845
846 IPCB(iter.frag)->flags = IPCB(skb)->flags;
847 ip_fraglist_prepare(skb, &iter);
848 if (first_frag && IPCB(skb)->opt.optlen) {
849 /* ipcb->opt is not populated for frags
850 * coming from __ip_make_skb(),
851 * ip_options_fragment() needs optlen
852 */
853 IPCB(iter.frag)->opt.optlen =
854 IPCB(skb)->opt.optlen;
855 ip_options_fragment(iter.frag);
856 ip_send_check(iter.iph);
857 }
858 }
859
860 skb_set_delivery_time(skb, tstamp, tstamp_type);
861 err = output(net, sk, skb);
862
863 if (!err)
864 IP_INC_STATS(net, IPSTATS_MIB_FRAGCREATES);
865 if (err || !iter.frag)
866 break;
867
868 skb = ip_fraglist_next(&iter);
869 }
870
871 if (err == 0) {
872 IP_INC_STATS(net, IPSTATS_MIB_FRAGOKS);
873 return 0;
874 }
875
876 kfree_skb_list(iter.frag);
877
878 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
879 return err;
880
881slow_path_clean:
882 skb_walk_frags(skb, frag2) {
883 if (frag2 == frag)
884 break;
885 frag2->sk = NULL;
886 frag2->destructor = NULL;
887 skb->truesize += frag2->truesize;
888 }
889 }
890
891slow_path:
892 /*
893 * Fragment the datagram.
894 */
895
896 ip_frag_init(skb, hlen, ll_rs, mtu, IPCB(skb)->flags & IPSKB_FRAG_PMTU,
897 &state);
898
899 /*
900 * Keep copying data until we run out.
901 */
902
903 while (state.left > 0) {
904 bool first_frag = (state.offset == 0);
905
906 skb2 = ip_frag_next(skb, &state);
907 if (IS_ERR(skb2)) {
908 err = PTR_ERR(skb2);
909 goto fail;
910 }
911 ip_frag_ipcb(skb, skb2, first_frag);
912
913 /*
914 * Put this fragment into the sending queue.
915 */
916 skb_set_delivery_time(skb2, tstamp, tstamp_type);
917 err = output(net, sk, skb2);
918 if (err)
919 goto fail;
920
921 IP_INC_STATS(net, IPSTATS_MIB_FRAGCREATES);
922 }
923 consume_skb(skb);
924 IP_INC_STATS(net, IPSTATS_MIB_FRAGOKS);
925 return err;
926
927fail:
928 kfree_skb(skb);
929 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
930 return err;
931}
932EXPORT_SYMBOL(ip_do_fragment);
933
934int
935ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
936{
937 struct msghdr *msg = from;
938
939 if (skb->ip_summed == CHECKSUM_PARTIAL) {
940 if (!copy_from_iter_full(to, len, &msg->msg_iter))
941 return -EFAULT;
942 } else {
943 __wsum csum = 0;
944 if (!csum_and_copy_from_iter_full(to, len, &csum, &msg->msg_iter))
945 return -EFAULT;
946 skb->csum = csum_block_add(skb->csum, csum, odd);
947 }
948 return 0;
949}
950EXPORT_SYMBOL(ip_generic_getfrag);
951
952static int __ip_append_data(struct sock *sk,
953 struct flowi4 *fl4,
954 struct sk_buff_head *queue,
955 struct inet_cork *cork,
956 struct page_frag *pfrag,
957 int getfrag(void *from, char *to, int offset,
958 int len, int odd, struct sk_buff *skb),
959 void *from, int length, int transhdrlen,
960 unsigned int flags)
961{
962 struct inet_sock *inet = inet_sk(sk);
963 struct ubuf_info *uarg = NULL;
964 struct sk_buff *skb;
965 struct ip_options *opt = cork->opt;
966 int hh_len;
967 int exthdrlen;
968 int mtu;
969 int copy;
970 int err;
971 int offset = 0;
972 bool zc = false;
973 unsigned int maxfraglen, fragheaderlen, maxnonfragsize;
974 int csummode = CHECKSUM_NONE;
975 struct rtable *rt = dst_rtable(cork->dst);
976 bool paged, hold_tskey = false, extra_uref = false;
977 unsigned int wmem_alloc_delta = 0;
978 u32 tskey = 0;
979
980 skb = skb_peek_tail(queue);
981
982 exthdrlen = !skb ? rt->dst.header_len : 0;
983 mtu = cork->gso_size ? IP_MAX_MTU : cork->fragsize;
984 paged = !!cork->gso_size;
985
986 hh_len = LL_RESERVED_SPACE(rt->dst.dev);
987
988 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
989 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
990 maxnonfragsize = ip_sk_ignore_df(sk) ? IP_MAX_MTU : mtu;
991
992 if (cork->length + length > maxnonfragsize - fragheaderlen) {
993 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
994 mtu - (opt ? opt->optlen : 0));
995 return -EMSGSIZE;
996 }
997
998 /*
999 * transhdrlen > 0 means that this is the first fragment and we wish
1000 * it won't be fragmented in the future.
1001 */
1002 if (transhdrlen &&
1003 length + fragheaderlen <= mtu &&
1004 rt->dst.dev->features & (NETIF_F_HW_CSUM | NETIF_F_IP_CSUM) &&
1005 (!(flags & MSG_MORE) || cork->gso_size) &&
1006 (!exthdrlen || (rt->dst.dev->features & NETIF_F_HW_ESP_TX_CSUM)))
1007 csummode = CHECKSUM_PARTIAL;
1008
1009 if ((flags & MSG_ZEROCOPY) && length) {
1010 struct msghdr *msg = from;
1011
1012 if (getfrag == ip_generic_getfrag && msg->msg_ubuf) {
1013 if (skb_zcopy(skb) && msg->msg_ubuf != skb_zcopy(skb))
1014 return -EINVAL;
1015
1016 /* Leave uarg NULL if can't zerocopy, callers should
1017 * be able to handle it.
1018 */
1019 if ((rt->dst.dev->features & NETIF_F_SG) &&
1020 csummode == CHECKSUM_PARTIAL) {
1021 paged = true;
1022 zc = true;
1023 uarg = msg->msg_ubuf;
1024 }
1025 } else if (sock_flag(sk, SOCK_ZEROCOPY)) {
1026 uarg = msg_zerocopy_realloc(sk, length, skb_zcopy(skb));
1027 if (!uarg)
1028 return -ENOBUFS;
1029 extra_uref = !skb_zcopy(skb); /* only ref on new uarg */
1030 if (rt->dst.dev->features & NETIF_F_SG &&
1031 csummode == CHECKSUM_PARTIAL) {
1032 paged = true;
1033 zc = true;
1034 } else {
1035 uarg_to_msgzc(uarg)->zerocopy = 0;
1036 skb_zcopy_set(skb, uarg, &extra_uref);
1037 }
1038 }
1039 } else if ((flags & MSG_SPLICE_PAGES) && length) {
1040 if (inet_test_bit(HDRINCL, sk))
1041 return -EPERM;
1042 if (rt->dst.dev->features & NETIF_F_SG &&
1043 getfrag == ip_generic_getfrag)
1044 /* We need an empty buffer to attach stuff to */
1045 paged = true;
1046 else
1047 flags &= ~MSG_SPLICE_PAGES;
1048 }
1049
1050 cork->length += length;
1051
1052 if (cork->tx_flags & SKBTX_ANY_TSTAMP &&
1053 READ_ONCE(sk->sk_tsflags) & SOF_TIMESTAMPING_OPT_ID) {
1054 if (cork->flags & IPCORK_TS_OPT_ID) {
1055 tskey = cork->ts_opt_id;
1056 } else {
1057 tskey = atomic_inc_return(&sk->sk_tskey) - 1;
1058 hold_tskey = true;
1059 }
1060 }
1061
1062 /* So, what's going on in the loop below?
1063 *
1064 * We use calculated fragment length to generate chained skb,
1065 * each of segments is IP fragment ready for sending to network after
1066 * adding appropriate IP header.
1067 */
1068
1069 if (!skb)
1070 goto alloc_new_skb;
1071
1072 while (length > 0) {
1073 /* Check if the remaining data fits into current packet. */
1074 copy = mtu - skb->len;
1075 if (copy < length)
1076 copy = maxfraglen - skb->len;
1077 if (copy <= 0) {
1078 char *data;
1079 unsigned int datalen;
1080 unsigned int fraglen;
1081 unsigned int fraggap;
1082 unsigned int alloclen, alloc_extra;
1083 unsigned int pagedlen;
1084 struct sk_buff *skb_prev;
1085alloc_new_skb:
1086 skb_prev = skb;
1087 if (skb_prev)
1088 fraggap = skb_prev->len - maxfraglen;
1089 else
1090 fraggap = 0;
1091
1092 /*
1093 * If remaining data exceeds the mtu,
1094 * we know we need more fragment(s).
1095 */
1096 datalen = length + fraggap;
1097 if (datalen > mtu - fragheaderlen)
1098 datalen = maxfraglen - fragheaderlen;
1099 fraglen = datalen + fragheaderlen;
1100 pagedlen = 0;
1101
1102 alloc_extra = hh_len + 15;
1103 alloc_extra += exthdrlen;
1104
1105 /* The last fragment gets additional space at tail.
1106 * Note, with MSG_MORE we overallocate on fragments,
1107 * because we have no idea what fragment will be
1108 * the last.
1109 */
1110 if (datalen == length + fraggap)
1111 alloc_extra += rt->dst.trailer_len;
1112
1113 if ((flags & MSG_MORE) &&
1114 !(rt->dst.dev->features&NETIF_F_SG))
1115 alloclen = mtu;
1116 else if (!paged &&
1117 (fraglen + alloc_extra < SKB_MAX_ALLOC ||
1118 !(rt->dst.dev->features & NETIF_F_SG)))
1119 alloclen = fraglen;
1120 else {
1121 alloclen = fragheaderlen + transhdrlen;
1122 pagedlen = datalen - transhdrlen;
1123 }
1124
1125 alloclen += alloc_extra;
1126
1127 if (transhdrlen) {
1128 skb = sock_alloc_send_skb(sk, alloclen,
1129 (flags & MSG_DONTWAIT), &err);
1130 } else {
1131 skb = NULL;
1132 if (refcount_read(&sk->sk_wmem_alloc) + wmem_alloc_delta <=
1133 2 * sk->sk_sndbuf)
1134 skb = alloc_skb(alloclen,
1135 sk->sk_allocation);
1136 if (unlikely(!skb))
1137 err = -ENOBUFS;
1138 }
1139 if (!skb)
1140 goto error;
1141
1142 /*
1143 * Fill in the control structures
1144 */
1145 skb->ip_summed = csummode;
1146 skb->csum = 0;
1147 skb_reserve(skb, hh_len);
1148
1149 /*
1150 * Find where to start putting bytes.
1151 */
1152 data = skb_put(skb, fraglen + exthdrlen - pagedlen);
1153 skb_set_network_header(skb, exthdrlen);
1154 skb->transport_header = (skb->network_header +
1155 fragheaderlen);
1156 data += fragheaderlen + exthdrlen;
1157
1158 if (fraggap) {
1159 skb->csum = skb_copy_and_csum_bits(
1160 skb_prev, maxfraglen,
1161 data + transhdrlen, fraggap);
1162 skb_prev->csum = csum_sub(skb_prev->csum,
1163 skb->csum);
1164 data += fraggap;
1165 pskb_trim_unique(skb_prev, maxfraglen);
1166 }
1167
1168 copy = datalen - transhdrlen - fraggap - pagedlen;
1169 /* [!] NOTE: copy will be negative if pagedlen>0
1170 * because then the equation reduces to -fraggap.
1171 */
1172 if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) {
1173 err = -EFAULT;
1174 kfree_skb(skb);
1175 goto error;
1176 } else if (flags & MSG_SPLICE_PAGES) {
1177 copy = 0;
1178 }
1179
1180 offset += copy;
1181 length -= copy + transhdrlen;
1182 transhdrlen = 0;
1183 exthdrlen = 0;
1184 csummode = CHECKSUM_NONE;
1185
1186 /* only the initial fragment is time stamped */
1187 skb_shinfo(skb)->tx_flags = cork->tx_flags;
1188 cork->tx_flags = 0;
1189 skb_shinfo(skb)->tskey = tskey;
1190 tskey = 0;
1191 skb_zcopy_set(skb, uarg, &extra_uref);
1192
1193 if ((flags & MSG_CONFIRM) && !skb_prev)
1194 skb_set_dst_pending_confirm(skb, 1);
1195
1196 /*
1197 * Put the packet on the pending queue.
1198 */
1199 if (!skb->destructor) {
1200 skb->destructor = sock_wfree;
1201 skb->sk = sk;
1202 wmem_alloc_delta += skb->truesize;
1203 }
1204 __skb_queue_tail(queue, skb);
1205 continue;
1206 }
1207
1208 if (copy > length)
1209 copy = length;
1210
1211 if (!(rt->dst.dev->features&NETIF_F_SG) &&
1212 skb_tailroom(skb) >= copy) {
1213 unsigned int off;
1214
1215 off = skb->len;
1216 if (getfrag(from, skb_put(skb, copy),
1217 offset, copy, off, skb) < 0) {
1218 __skb_trim(skb, off);
1219 err = -EFAULT;
1220 goto error;
1221 }
1222 } else if (flags & MSG_SPLICE_PAGES) {
1223 struct msghdr *msg = from;
1224
1225 err = -EIO;
1226 if (WARN_ON_ONCE(copy > msg->msg_iter.count))
1227 goto error;
1228
1229 err = skb_splice_from_iter(skb, &msg->msg_iter, copy,
1230 sk->sk_allocation);
1231 if (err < 0)
1232 goto error;
1233 copy = err;
1234 wmem_alloc_delta += copy;
1235 } else if (!zc) {
1236 int i = skb_shinfo(skb)->nr_frags;
1237
1238 err = -ENOMEM;
1239 if (!sk_page_frag_refill(sk, pfrag))
1240 goto error;
1241
1242 skb_zcopy_downgrade_managed(skb);
1243 if (!skb_can_coalesce(skb, i, pfrag->page,
1244 pfrag->offset)) {
1245 err = -EMSGSIZE;
1246 if (i == MAX_SKB_FRAGS)
1247 goto error;
1248
1249 __skb_fill_page_desc(skb, i, pfrag->page,
1250 pfrag->offset, 0);
1251 skb_shinfo(skb)->nr_frags = ++i;
1252 get_page(pfrag->page);
1253 }
1254 copy = min_t(int, copy, pfrag->size - pfrag->offset);
1255 if (getfrag(from,
1256 page_address(pfrag->page) + pfrag->offset,
1257 offset, copy, skb->len, skb) < 0)
1258 goto error_efault;
1259
1260 pfrag->offset += copy;
1261 skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
1262 skb_len_add(skb, copy);
1263 wmem_alloc_delta += copy;
1264 } else {
1265 err = skb_zerocopy_iter_dgram(skb, from, copy);
1266 if (err < 0)
1267 goto error;
1268 }
1269 offset += copy;
1270 length -= copy;
1271 }
1272
1273 if (wmem_alloc_delta)
1274 refcount_add(wmem_alloc_delta, &sk->sk_wmem_alloc);
1275 return 0;
1276
1277error_efault:
1278 err = -EFAULT;
1279error:
1280 net_zcopy_put_abort(uarg, extra_uref);
1281 cork->length -= length;
1282 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1283 refcount_add(wmem_alloc_delta, &sk->sk_wmem_alloc);
1284 if (hold_tskey)
1285 atomic_dec(&sk->sk_tskey);
1286 return err;
1287}
1288
1289static int ip_setup_cork(struct sock *sk, struct inet_cork *cork,
1290 struct ipcm_cookie *ipc, struct rtable **rtp)
1291{
1292 struct ip_options_rcu *opt;
1293 struct rtable *rt;
1294
1295 rt = *rtp;
1296 if (unlikely(!rt))
1297 return -EFAULT;
1298
1299 cork->fragsize = ip_sk_use_pmtu(sk) ?
1300 dst_mtu(&rt->dst) : READ_ONCE(rt->dst.dev->mtu);
1301
1302 if (!inetdev_valid_mtu(cork->fragsize))
1303 return -ENETUNREACH;
1304
1305 /*
1306 * setup for corking.
1307 */
1308 opt = ipc->opt;
1309 if (opt) {
1310 if (!cork->opt) {
1311 cork->opt = kmalloc(sizeof(struct ip_options) + 40,
1312 sk->sk_allocation);
1313 if (unlikely(!cork->opt))
1314 return -ENOBUFS;
1315 }
1316 memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen);
1317 cork->flags |= IPCORK_OPT;
1318 cork->addr = ipc->addr;
1319 }
1320
1321 cork->gso_size = ipc->gso_size;
1322
1323 cork->dst = &rt->dst;
1324 /* We stole this route, caller should not release it. */
1325 *rtp = NULL;
1326
1327 cork->length = 0;
1328 cork->ttl = ipc->ttl;
1329 cork->tos = ipc->tos;
1330 cork->mark = ipc->sockc.mark;
1331 cork->priority = ipc->priority;
1332 cork->transmit_time = ipc->sockc.transmit_time;
1333 cork->tx_flags = 0;
1334 sock_tx_timestamp(sk, &ipc->sockc, &cork->tx_flags);
1335 if (ipc->sockc.tsflags & SOCKCM_FLAG_TS_OPT_ID) {
1336 cork->flags |= IPCORK_TS_OPT_ID;
1337 cork->ts_opt_id = ipc->sockc.ts_opt_id;
1338 }
1339
1340 return 0;
1341}
1342
1343/*
1344 * ip_append_data() can make one large IP datagram from many pieces of
1345 * data. Each piece will be held on the socket until
1346 * ip_push_pending_frames() is called. Each piece can be a page or
1347 * non-page data.
1348 *
1349 * Not only UDP, other transport protocols - e.g. raw sockets - can use
1350 * this interface potentially.
1351 *
1352 * LATER: length must be adjusted by pad at tail, when it is required.
1353 */
1354int ip_append_data(struct sock *sk, struct flowi4 *fl4,
1355 int getfrag(void *from, char *to, int offset, int len,
1356 int odd, struct sk_buff *skb),
1357 void *from, int length, int transhdrlen,
1358 struct ipcm_cookie *ipc, struct rtable **rtp,
1359 unsigned int flags)
1360{
1361 struct inet_sock *inet = inet_sk(sk);
1362 int err;
1363
1364 if (flags&MSG_PROBE)
1365 return 0;
1366
1367 if (skb_queue_empty(&sk->sk_write_queue)) {
1368 err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp);
1369 if (err)
1370 return err;
1371 } else {
1372 transhdrlen = 0;
1373 }
1374
1375 return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base,
1376 sk_page_frag(sk), getfrag,
1377 from, length, transhdrlen, flags);
1378}
1379
1380static void ip_cork_release(struct inet_cork *cork)
1381{
1382 cork->flags &= ~IPCORK_OPT;
1383 kfree(cork->opt);
1384 cork->opt = NULL;
1385 dst_release(cork->dst);
1386 cork->dst = NULL;
1387}
1388
1389/*
1390 * Combined all pending IP fragments on the socket as one IP datagram
1391 * and push them out.
1392 */
1393struct sk_buff *__ip_make_skb(struct sock *sk,
1394 struct flowi4 *fl4,
1395 struct sk_buff_head *queue,
1396 struct inet_cork *cork)
1397{
1398 struct sk_buff *skb, *tmp_skb;
1399 struct sk_buff **tail_skb;
1400 struct inet_sock *inet = inet_sk(sk);
1401 struct net *net = sock_net(sk);
1402 struct ip_options *opt = NULL;
1403 struct rtable *rt = dst_rtable(cork->dst);
1404 struct iphdr *iph;
1405 u8 pmtudisc, ttl;
1406 __be16 df = 0;
1407
1408 skb = __skb_dequeue(queue);
1409 if (!skb)
1410 goto out;
1411 tail_skb = &(skb_shinfo(skb)->frag_list);
1412
1413 /* move skb->data to ip header from ext header */
1414 if (skb->data < skb_network_header(skb))
1415 __skb_pull(skb, skb_network_offset(skb));
1416 while ((tmp_skb = __skb_dequeue(queue)) != NULL) {
1417 __skb_pull(tmp_skb, skb_network_header_len(skb));
1418 *tail_skb = tmp_skb;
1419 tail_skb = &(tmp_skb->next);
1420 skb->len += tmp_skb->len;
1421 skb->data_len += tmp_skb->len;
1422 skb->truesize += tmp_skb->truesize;
1423 tmp_skb->destructor = NULL;
1424 tmp_skb->sk = NULL;
1425 }
1426
1427 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow
1428 * to fragment the frame generated here. No matter, what transforms
1429 * how transforms change size of the packet, it will come out.
1430 */
1431 skb->ignore_df = ip_sk_ignore_df(sk);
1432
1433 /* DF bit is set when we want to see DF on outgoing frames.
1434 * If ignore_df is set too, we still allow to fragment this frame
1435 * locally. */
1436 pmtudisc = READ_ONCE(inet->pmtudisc);
1437 if (pmtudisc == IP_PMTUDISC_DO ||
1438 pmtudisc == IP_PMTUDISC_PROBE ||
1439 (skb->len <= dst_mtu(&rt->dst) &&
1440 ip_dont_fragment(sk, &rt->dst)))
1441 df = htons(IP_DF);
1442
1443 if (cork->flags & IPCORK_OPT)
1444 opt = cork->opt;
1445
1446 if (cork->ttl != 0)
1447 ttl = cork->ttl;
1448 else if (rt->rt_type == RTN_MULTICAST)
1449 ttl = READ_ONCE(inet->mc_ttl);
1450 else
1451 ttl = ip_select_ttl(inet, &rt->dst);
1452
1453 iph = ip_hdr(skb);
1454 iph->version = 4;
1455 iph->ihl = 5;
1456 iph->tos = (cork->tos != -1) ? cork->tos : READ_ONCE(inet->tos);
1457 iph->frag_off = df;
1458 iph->ttl = ttl;
1459 iph->protocol = sk->sk_protocol;
1460 ip_copy_addrs(iph, fl4);
1461 ip_select_ident(net, skb, sk);
1462
1463 if (opt) {
1464 iph->ihl += opt->optlen >> 2;
1465 ip_options_build(skb, opt, cork->addr, rt);
1466 }
1467
1468 skb->priority = (cork->tos != -1) ? cork->priority: READ_ONCE(sk->sk_priority);
1469 skb->mark = cork->mark;
1470 if (sk_is_tcp(sk))
1471 skb_set_delivery_time(skb, cork->transmit_time, SKB_CLOCK_MONOTONIC);
1472 else
1473 skb_set_delivery_type_by_clockid(skb, cork->transmit_time, sk->sk_clockid);
1474 /*
1475 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec
1476 * on dst refcount
1477 */
1478 cork->dst = NULL;
1479 skb_dst_set(skb, &rt->dst);
1480
1481 if (iph->protocol == IPPROTO_ICMP) {
1482 u8 icmp_type;
1483
1484 /* For such sockets, transhdrlen is zero when do ip_append_data(),
1485 * so icmphdr does not in skb linear region and can not get icmp_type
1486 * by icmp_hdr(skb)->type.
1487 */
1488 if (sk->sk_type == SOCK_RAW &&
1489 !(fl4->flowi4_flags & FLOWI_FLAG_KNOWN_NH))
1490 icmp_type = fl4->fl4_icmp_type;
1491 else
1492 icmp_type = icmp_hdr(skb)->type;
1493 icmp_out_count(net, icmp_type);
1494 }
1495
1496 ip_cork_release(cork);
1497out:
1498 return skb;
1499}
1500
1501int ip_send_skb(struct net *net, struct sk_buff *skb)
1502{
1503 int err;
1504
1505 err = ip_local_out(net, skb->sk, skb);
1506 if (err) {
1507 if (err > 0)
1508 err = net_xmit_errno(err);
1509 if (err)
1510 IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS);
1511 }
1512
1513 return err;
1514}
1515
1516int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4)
1517{
1518 struct sk_buff *skb;
1519
1520 skb = ip_finish_skb(sk, fl4);
1521 if (!skb)
1522 return 0;
1523
1524 /* Netfilter gets whole the not fragmented skb. */
1525 return ip_send_skb(sock_net(sk), skb);
1526}
1527
1528/*
1529 * Throw away all pending data on the socket.
1530 */
1531static void __ip_flush_pending_frames(struct sock *sk,
1532 struct sk_buff_head *queue,
1533 struct inet_cork *cork)
1534{
1535 struct sk_buff *skb;
1536
1537 while ((skb = __skb_dequeue_tail(queue)) != NULL)
1538 kfree_skb(skb);
1539
1540 ip_cork_release(cork);
1541}
1542
1543void ip_flush_pending_frames(struct sock *sk)
1544{
1545 __ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork.base);
1546}
1547
1548struct sk_buff *ip_make_skb(struct sock *sk,
1549 struct flowi4 *fl4,
1550 int getfrag(void *from, char *to, int offset,
1551 int len, int odd, struct sk_buff *skb),
1552 void *from, int length, int transhdrlen,
1553 struct ipcm_cookie *ipc, struct rtable **rtp,
1554 struct inet_cork *cork, unsigned int flags)
1555{
1556 struct sk_buff_head queue;
1557 int err;
1558
1559 if (flags & MSG_PROBE)
1560 return NULL;
1561
1562 __skb_queue_head_init(&queue);
1563
1564 cork->flags = 0;
1565 cork->addr = 0;
1566 cork->opt = NULL;
1567 err = ip_setup_cork(sk, cork, ipc, rtp);
1568 if (err)
1569 return ERR_PTR(err);
1570
1571 err = __ip_append_data(sk, fl4, &queue, cork,
1572 ¤t->task_frag, getfrag,
1573 from, length, transhdrlen, flags);
1574 if (err) {
1575 __ip_flush_pending_frames(sk, &queue, cork);
1576 return ERR_PTR(err);
1577 }
1578
1579 return __ip_make_skb(sk, fl4, &queue, cork);
1580}
1581
1582/*
1583 * Fetch data from kernel space and fill in checksum if needed.
1584 */
1585static int ip_reply_glue_bits(void *dptr, char *to, int offset,
1586 int len, int odd, struct sk_buff *skb)
1587{
1588 __wsum csum;
1589
1590 csum = csum_partial_copy_nocheck(dptr+offset, to, len);
1591 skb->csum = csum_block_add(skb->csum, csum, odd);
1592 return 0;
1593}
1594
1595/*
1596 * Generic function to send a packet as reply to another packet.
1597 * Used to send some TCP resets/acks so far.
1598 */
1599void ip_send_unicast_reply(struct sock *sk, const struct sock *orig_sk,
1600 struct sk_buff *skb,
1601 const struct ip_options *sopt,
1602 __be32 daddr, __be32 saddr,
1603 const struct ip_reply_arg *arg,
1604 unsigned int len, u64 transmit_time, u32 txhash)
1605{
1606 struct ip_options_data replyopts;
1607 struct ipcm_cookie ipc;
1608 struct flowi4 fl4;
1609 struct rtable *rt = skb_rtable(skb);
1610 struct net *net = sock_net(sk);
1611 struct sk_buff *nskb;
1612 int err;
1613 int oif;
1614
1615 if (__ip_options_echo(net, &replyopts.opt.opt, skb, sopt))
1616 return;
1617
1618 ipcm_init(&ipc);
1619 ipc.addr = daddr;
1620 ipc.sockc.transmit_time = transmit_time;
1621
1622 if (replyopts.opt.opt.optlen) {
1623 ipc.opt = &replyopts.opt;
1624
1625 if (replyopts.opt.opt.srr)
1626 daddr = replyopts.opt.opt.faddr;
1627 }
1628
1629 oif = arg->bound_dev_if;
1630 if (!oif && netif_index_is_l3_master(net, skb->skb_iif))
1631 oif = skb->skb_iif;
1632
1633 flowi4_init_output(&fl4, oif,
1634 IP4_REPLY_MARK(net, skb->mark) ?: sk->sk_mark,
1635 arg->tos & INET_DSCP_MASK,
1636 RT_SCOPE_UNIVERSE, ip_hdr(skb)->protocol,
1637 ip_reply_arg_flowi_flags(arg),
1638 daddr, saddr,
1639 tcp_hdr(skb)->source, tcp_hdr(skb)->dest,
1640 arg->uid);
1641 security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4));
1642 rt = ip_route_output_flow(net, &fl4, sk);
1643 if (IS_ERR(rt))
1644 return;
1645
1646 inet_sk(sk)->tos = arg->tos & ~INET_ECN_MASK;
1647
1648 sk->sk_protocol = ip_hdr(skb)->protocol;
1649 sk->sk_bound_dev_if = arg->bound_dev_if;
1650 sk->sk_sndbuf = READ_ONCE(sysctl_wmem_default);
1651 ipc.sockc.mark = fl4.flowi4_mark;
1652 err = ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base,
1653 len, 0, &ipc, &rt, MSG_DONTWAIT);
1654 if (unlikely(err)) {
1655 ip_flush_pending_frames(sk);
1656 goto out;
1657 }
1658
1659 nskb = skb_peek(&sk->sk_write_queue);
1660 if (nskb) {
1661 if (arg->csumoffset >= 0)
1662 *((__sum16 *)skb_transport_header(nskb) +
1663 arg->csumoffset) = csum_fold(csum_add(nskb->csum,
1664 arg->csum));
1665 nskb->ip_summed = CHECKSUM_NONE;
1666 if (orig_sk)
1667 skb_set_owner_edemux(nskb, (struct sock *)orig_sk);
1668 if (transmit_time)
1669 nskb->tstamp_type = SKB_CLOCK_MONOTONIC;
1670 if (txhash)
1671 skb_set_hash(nskb, txhash, PKT_HASH_TYPE_L4);
1672 ip_push_pending_frames(sk, &fl4);
1673 }
1674out:
1675 ip_rt_put(rt);
1676}
1677
1678void __init ip_init(void)
1679{
1680 ip_rt_init();
1681 inet_initpeers();
1682
1683#if defined(CONFIG_IP_MULTICAST)
1684 igmp_mc_init();
1685#endif
1686}
1/*
2 * INET An implementation of the TCP/IP protocol suite for the LINUX
3 * operating system. INET is implemented using the BSD Socket
4 * interface as the means of communication with the user level.
5 *
6 * The Internet Protocol (IP) output module.
7 *
8 * Authors: Ross Biro
9 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
10 * Donald Becker, <becker@super.org>
11 * Alan Cox, <Alan.Cox@linux.org>
12 * Richard Underwood
13 * Stefan Becker, <stefanb@yello.ping.de>
14 * Jorge Cwik, <jorge@laser.satlink.net>
15 * Arnt Gulbrandsen, <agulbra@nvg.unit.no>
16 * Hirokazu Takahashi, <taka@valinux.co.jp>
17 *
18 * See ip_input.c for original log
19 *
20 * Fixes:
21 * Alan Cox : Missing nonblock feature in ip_build_xmit.
22 * Mike Kilburn : htons() missing in ip_build_xmit.
23 * Bradford Johnson: Fix faulty handling of some frames when
24 * no route is found.
25 * Alexander Demenshin: Missing sk/skb free in ip_queue_xmit
26 * (in case if packet not accepted by
27 * output firewall rules)
28 * Mike McLagan : Routing by source
29 * Alexey Kuznetsov: use new route cache
30 * Andi Kleen: Fix broken PMTU recovery and remove
31 * some redundant tests.
32 * Vitaly E. Lavrov : Transparent proxy revived after year coma.
33 * Andi Kleen : Replace ip_reply with ip_send_reply.
34 * Andi Kleen : Split fast and slow ip_build_xmit path
35 * for decreased register pressure on x86
36 * and more readibility.
37 * Marc Boucher : When call_out_firewall returns FW_QUEUE,
38 * silently drop skb instead of failing with -EPERM.
39 * Detlev Wengorz : Copy protocol for fragments.
40 * Hirokazu Takahashi: HW checksumming for outgoing UDP
41 * datagrams.
42 * Hirokazu Takahashi: sendfile() on UDP works now.
43 */
44
45#include <asm/uaccess.h>
46#include <linux/module.h>
47#include <linux/types.h>
48#include <linux/kernel.h>
49#include <linux/mm.h>
50#include <linux/string.h>
51#include <linux/errno.h>
52#include <linux/highmem.h>
53#include <linux/slab.h>
54
55#include <linux/socket.h>
56#include <linux/sockios.h>
57#include <linux/in.h>
58#include <linux/inet.h>
59#include <linux/netdevice.h>
60#include <linux/etherdevice.h>
61#include <linux/proc_fs.h>
62#include <linux/stat.h>
63#include <linux/init.h>
64
65#include <net/snmp.h>
66#include <net/ip.h>
67#include <net/protocol.h>
68#include <net/route.h>
69#include <net/xfrm.h>
70#include <linux/skbuff.h>
71#include <net/sock.h>
72#include <net/arp.h>
73#include <net/icmp.h>
74#include <net/checksum.h>
75#include <net/inetpeer.h>
76#include <linux/igmp.h>
77#include <linux/netfilter_ipv4.h>
78#include <linux/netfilter_bridge.h>
79#include <linux/netlink.h>
80#include <linux/tcp.h>
81
82static int
83ip_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
84 unsigned int mtu,
85 int (*output)(struct net *, struct sock *, struct sk_buff *));
86
87/* Generate a checksum for an outgoing IP datagram. */
88void ip_send_check(struct iphdr *iph)
89{
90 iph->check = 0;
91 iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
92}
93EXPORT_SYMBOL(ip_send_check);
94
95int __ip_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
96{
97 struct iphdr *iph = ip_hdr(skb);
98
99 iph->tot_len = htons(skb->len);
100 ip_send_check(iph);
101 return nf_hook(NFPROTO_IPV4, NF_INET_LOCAL_OUT,
102 net, sk, skb, NULL, skb_dst(skb)->dev,
103 dst_output);
104}
105
106int ip_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
107{
108 int err;
109
110 err = __ip_local_out(net, sk, skb);
111 if (likely(err == 1))
112 err = dst_output(net, sk, skb);
113
114 return err;
115}
116EXPORT_SYMBOL_GPL(ip_local_out);
117
118static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst)
119{
120 int ttl = inet->uc_ttl;
121
122 if (ttl < 0)
123 ttl = ip4_dst_hoplimit(dst);
124 return ttl;
125}
126
127/*
128 * Add an ip header to a skbuff and send it out.
129 *
130 */
131int ip_build_and_send_pkt(struct sk_buff *skb, const struct sock *sk,
132 __be32 saddr, __be32 daddr, struct ip_options_rcu *opt)
133{
134 struct inet_sock *inet = inet_sk(sk);
135 struct rtable *rt = skb_rtable(skb);
136 struct net *net = sock_net(sk);
137 struct iphdr *iph;
138
139 /* Build the IP header. */
140 skb_push(skb, sizeof(struct iphdr) + (opt ? opt->opt.optlen : 0));
141 skb_reset_network_header(skb);
142 iph = ip_hdr(skb);
143 iph->version = 4;
144 iph->ihl = 5;
145 iph->tos = inet->tos;
146 iph->ttl = ip_select_ttl(inet, &rt->dst);
147 iph->daddr = (opt && opt->opt.srr ? opt->opt.faddr : daddr);
148 iph->saddr = saddr;
149 iph->protocol = sk->sk_protocol;
150 if (ip_dont_fragment(sk, &rt->dst)) {
151 iph->frag_off = htons(IP_DF);
152 iph->id = 0;
153 } else {
154 iph->frag_off = 0;
155 __ip_select_ident(net, iph, 1);
156 }
157
158 if (opt && opt->opt.optlen) {
159 iph->ihl += opt->opt.optlen>>2;
160 ip_options_build(skb, &opt->opt, daddr, rt, 0);
161 }
162
163 skb->priority = sk->sk_priority;
164 skb->mark = sk->sk_mark;
165
166 /* Send it out. */
167 return ip_local_out(net, skb->sk, skb);
168}
169EXPORT_SYMBOL_GPL(ip_build_and_send_pkt);
170
171static int ip_finish_output2(struct net *net, struct sock *sk, struct sk_buff *skb)
172{
173 struct dst_entry *dst = skb_dst(skb);
174 struct rtable *rt = (struct rtable *)dst;
175 struct net_device *dev = dst->dev;
176 unsigned int hh_len = LL_RESERVED_SPACE(dev);
177 struct neighbour *neigh;
178 u32 nexthop;
179
180 if (rt->rt_type == RTN_MULTICAST) {
181 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUTMCAST, skb->len);
182 } else if (rt->rt_type == RTN_BROADCAST)
183 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUTBCAST, skb->len);
184
185 /* Be paranoid, rather than too clever. */
186 if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) {
187 struct sk_buff *skb2;
188
189 skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev));
190 if (!skb2) {
191 kfree_skb(skb);
192 return -ENOMEM;
193 }
194 if (skb->sk)
195 skb_set_owner_w(skb2, skb->sk);
196 consume_skb(skb);
197 skb = skb2;
198 }
199
200 rcu_read_lock_bh();
201 nexthop = (__force u32) rt_nexthop(rt, ip_hdr(skb)->daddr);
202 neigh = __ipv4_neigh_lookup_noref(dev, nexthop);
203 if (unlikely(!neigh))
204 neigh = __neigh_create(&arp_tbl, &nexthop, dev, false);
205 if (!IS_ERR(neigh)) {
206 int res = dst_neigh_output(dst, neigh, skb);
207
208 rcu_read_unlock_bh();
209 return res;
210 }
211 rcu_read_unlock_bh();
212
213 net_dbg_ratelimited("%s: No header cache and no neighbour!\n",
214 __func__);
215 kfree_skb(skb);
216 return -EINVAL;
217}
218
219static int ip_finish_output_gso(struct net *net, struct sock *sk,
220 struct sk_buff *skb, unsigned int mtu)
221{
222 netdev_features_t features;
223 struct sk_buff *segs;
224 int ret = 0;
225
226 /* common case: locally created skb or seglen is <= mtu */
227 if (((IPCB(skb)->flags & IPSKB_FORWARDED) == 0) ||
228 skb_gso_network_seglen(skb) <= mtu)
229 return ip_finish_output2(net, sk, skb);
230
231 /* Slowpath - GSO segment length is exceeding the dst MTU.
232 *
233 * This can happen in two cases:
234 * 1) TCP GRO packet, DF bit not set
235 * 2) skb arrived via virtio-net, we thus get TSO/GSO skbs directly
236 * from host network stack.
237 */
238 features = netif_skb_features(skb);
239 BUILD_BUG_ON(sizeof(*IPCB(skb)) > SKB_SGO_CB_OFFSET);
240 segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK);
241 if (IS_ERR_OR_NULL(segs)) {
242 kfree_skb(skb);
243 return -ENOMEM;
244 }
245
246 consume_skb(skb);
247
248 do {
249 struct sk_buff *nskb = segs->next;
250 int err;
251
252 segs->next = NULL;
253 err = ip_fragment(net, sk, segs, mtu, ip_finish_output2);
254
255 if (err && ret == 0)
256 ret = err;
257 segs = nskb;
258 } while (segs);
259
260 return ret;
261}
262
263static int ip_finish_output(struct net *net, struct sock *sk, struct sk_buff *skb)
264{
265 unsigned int mtu;
266
267#if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
268 /* Policy lookup after SNAT yielded a new policy */
269 if (skb_dst(skb)->xfrm) {
270 IPCB(skb)->flags |= IPSKB_REROUTED;
271 return dst_output(net, sk, skb);
272 }
273#endif
274 mtu = ip_skb_dst_mtu(skb);
275 if (skb_is_gso(skb))
276 return ip_finish_output_gso(net, sk, skb, mtu);
277
278 if (skb->len > mtu || (IPCB(skb)->flags & IPSKB_FRAG_PMTU))
279 return ip_fragment(net, sk, skb, mtu, ip_finish_output2);
280
281 return ip_finish_output2(net, sk, skb);
282}
283
284int ip_mc_output(struct net *net, struct sock *sk, struct sk_buff *skb)
285{
286 struct rtable *rt = skb_rtable(skb);
287 struct net_device *dev = rt->dst.dev;
288
289 /*
290 * If the indicated interface is up and running, send the packet.
291 */
292 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUT, skb->len);
293
294 skb->dev = dev;
295 skb->protocol = htons(ETH_P_IP);
296
297 /*
298 * Multicasts are looped back for other local users
299 */
300
301 if (rt->rt_flags&RTCF_MULTICAST) {
302 if (sk_mc_loop(sk)
303#ifdef CONFIG_IP_MROUTE
304 /* Small optimization: do not loopback not local frames,
305 which returned after forwarding; they will be dropped
306 by ip_mr_input in any case.
307 Note, that local frames are looped back to be delivered
308 to local recipients.
309
310 This check is duplicated in ip_mr_input at the moment.
311 */
312 &&
313 ((rt->rt_flags & RTCF_LOCAL) ||
314 !(IPCB(skb)->flags & IPSKB_FORWARDED))
315#endif
316 ) {
317 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
318 if (newskb)
319 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
320 net, sk, newskb, NULL, newskb->dev,
321 dev_loopback_xmit);
322 }
323
324 /* Multicasts with ttl 0 must not go beyond the host */
325
326 if (ip_hdr(skb)->ttl == 0) {
327 kfree_skb(skb);
328 return 0;
329 }
330 }
331
332 if (rt->rt_flags&RTCF_BROADCAST) {
333 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
334 if (newskb)
335 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
336 net, sk, newskb, NULL, newskb->dev,
337 dev_loopback_xmit);
338 }
339
340 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
341 net, sk, skb, NULL, skb->dev,
342 ip_finish_output,
343 !(IPCB(skb)->flags & IPSKB_REROUTED));
344}
345
346int ip_output(struct net *net, struct sock *sk, struct sk_buff *skb)
347{
348 struct net_device *dev = skb_dst(skb)->dev;
349
350 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUT, skb->len);
351
352 skb->dev = dev;
353 skb->protocol = htons(ETH_P_IP);
354
355 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
356 net, sk, skb, NULL, dev,
357 ip_finish_output,
358 !(IPCB(skb)->flags & IPSKB_REROUTED));
359}
360
361/*
362 * copy saddr and daddr, possibly using 64bit load/stores
363 * Equivalent to :
364 * iph->saddr = fl4->saddr;
365 * iph->daddr = fl4->daddr;
366 */
367static void ip_copy_addrs(struct iphdr *iph, const struct flowi4 *fl4)
368{
369 BUILD_BUG_ON(offsetof(typeof(*fl4), daddr) !=
370 offsetof(typeof(*fl4), saddr) + sizeof(fl4->saddr));
371 memcpy(&iph->saddr, &fl4->saddr,
372 sizeof(fl4->saddr) + sizeof(fl4->daddr));
373}
374
375/* Note: skb->sk can be different from sk, in case of tunnels */
376int ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl)
377{
378 struct inet_sock *inet = inet_sk(sk);
379 struct net *net = sock_net(sk);
380 struct ip_options_rcu *inet_opt;
381 struct flowi4 *fl4;
382 struct rtable *rt;
383 struct iphdr *iph;
384 int res;
385
386 /* Skip all of this if the packet is already routed,
387 * f.e. by something like SCTP.
388 */
389 rcu_read_lock();
390 inet_opt = rcu_dereference(inet->inet_opt);
391 fl4 = &fl->u.ip4;
392 rt = skb_rtable(skb);
393 if (rt)
394 goto packet_routed;
395
396 /* Make sure we can route this packet. */
397 rt = (struct rtable *)__sk_dst_check(sk, 0);
398 if (!rt) {
399 __be32 daddr;
400
401 /* Use correct destination address if we have options. */
402 daddr = inet->inet_daddr;
403 if (inet_opt && inet_opt->opt.srr)
404 daddr = inet_opt->opt.faddr;
405
406 /* If this fails, retransmit mechanism of transport layer will
407 * keep trying until route appears or the connection times
408 * itself out.
409 */
410 rt = ip_route_output_ports(net, fl4, sk,
411 daddr, inet->inet_saddr,
412 inet->inet_dport,
413 inet->inet_sport,
414 sk->sk_protocol,
415 RT_CONN_FLAGS(sk),
416 sk->sk_bound_dev_if);
417 if (IS_ERR(rt))
418 goto no_route;
419 sk_setup_caps(sk, &rt->dst);
420 }
421 skb_dst_set_noref(skb, &rt->dst);
422
423packet_routed:
424 if (inet_opt && inet_opt->opt.is_strictroute && rt->rt_uses_gateway)
425 goto no_route;
426
427 /* OK, we know where to send it, allocate and build IP header. */
428 skb_push(skb, sizeof(struct iphdr) + (inet_opt ? inet_opt->opt.optlen : 0));
429 skb_reset_network_header(skb);
430 iph = ip_hdr(skb);
431 *((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (inet->tos & 0xff));
432 if (ip_dont_fragment(sk, &rt->dst) && !skb->ignore_df)
433 iph->frag_off = htons(IP_DF);
434 else
435 iph->frag_off = 0;
436 iph->ttl = ip_select_ttl(inet, &rt->dst);
437 iph->protocol = sk->sk_protocol;
438 ip_copy_addrs(iph, fl4);
439
440 /* Transport layer set skb->h.foo itself. */
441
442 if (inet_opt && inet_opt->opt.optlen) {
443 iph->ihl += inet_opt->opt.optlen >> 2;
444 ip_options_build(skb, &inet_opt->opt, inet->inet_daddr, rt, 0);
445 }
446
447 ip_select_ident_segs(net, skb, sk,
448 skb_shinfo(skb)->gso_segs ?: 1);
449
450 /* TODO : should we use skb->sk here instead of sk ? */
451 skb->priority = sk->sk_priority;
452 skb->mark = sk->sk_mark;
453
454 res = ip_local_out(net, sk, skb);
455 rcu_read_unlock();
456 return res;
457
458no_route:
459 rcu_read_unlock();
460 IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
461 kfree_skb(skb);
462 return -EHOSTUNREACH;
463}
464EXPORT_SYMBOL(ip_queue_xmit);
465
466static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from)
467{
468 to->pkt_type = from->pkt_type;
469 to->priority = from->priority;
470 to->protocol = from->protocol;
471 skb_dst_drop(to);
472 skb_dst_copy(to, from);
473 to->dev = from->dev;
474 to->mark = from->mark;
475
476 /* Copy the flags to each fragment. */
477 IPCB(to)->flags = IPCB(from)->flags;
478
479#ifdef CONFIG_NET_SCHED
480 to->tc_index = from->tc_index;
481#endif
482 nf_copy(to, from);
483#if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
484 to->ipvs_property = from->ipvs_property;
485#endif
486 skb_copy_secmark(to, from);
487}
488
489static int ip_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
490 unsigned int mtu,
491 int (*output)(struct net *, struct sock *, struct sk_buff *))
492{
493 struct iphdr *iph = ip_hdr(skb);
494
495 if ((iph->frag_off & htons(IP_DF)) == 0)
496 return ip_do_fragment(net, sk, skb, output);
497
498 if (unlikely(!skb->ignore_df ||
499 (IPCB(skb)->frag_max_size &&
500 IPCB(skb)->frag_max_size > mtu))) {
501 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
502 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
503 htonl(mtu));
504 kfree_skb(skb);
505 return -EMSGSIZE;
506 }
507
508 return ip_do_fragment(net, sk, skb, output);
509}
510
511/*
512 * This IP datagram is too large to be sent in one piece. Break it up into
513 * smaller pieces (each of size equal to IP header plus
514 * a block of the data of the original IP data part) that will yet fit in a
515 * single device frame, and queue such a frame for sending.
516 */
517
518int ip_do_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
519 int (*output)(struct net *, struct sock *, struct sk_buff *))
520{
521 struct iphdr *iph;
522 int ptr;
523 struct net_device *dev;
524 struct sk_buff *skb2;
525 unsigned int mtu, hlen, left, len, ll_rs;
526 int offset;
527 __be16 not_last_frag;
528 struct rtable *rt = skb_rtable(skb);
529 int err = 0;
530
531 dev = rt->dst.dev;
532
533 /* for offloaded checksums cleanup checksum before fragmentation */
534 if (skb->ip_summed == CHECKSUM_PARTIAL &&
535 (err = skb_checksum_help(skb)))
536 goto fail;
537
538 /*
539 * Point into the IP datagram header.
540 */
541
542 iph = ip_hdr(skb);
543
544 mtu = ip_skb_dst_mtu(skb);
545 if (IPCB(skb)->frag_max_size && IPCB(skb)->frag_max_size < mtu)
546 mtu = IPCB(skb)->frag_max_size;
547
548 /*
549 * Setup starting values.
550 */
551
552 hlen = iph->ihl * 4;
553 mtu = mtu - hlen; /* Size of data space */
554 IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE;
555
556 /* When frag_list is given, use it. First, check its validity:
557 * some transformers could create wrong frag_list or break existing
558 * one, it is not prohibited. In this case fall back to copying.
559 *
560 * LATER: this step can be merged to real generation of fragments,
561 * we can switch to copy when see the first bad fragment.
562 */
563 if (skb_has_frag_list(skb)) {
564 struct sk_buff *frag, *frag2;
565 int first_len = skb_pagelen(skb);
566
567 if (first_len - hlen > mtu ||
568 ((first_len - hlen) & 7) ||
569 ip_is_fragment(iph) ||
570 skb_cloned(skb))
571 goto slow_path;
572
573 skb_walk_frags(skb, frag) {
574 /* Correct geometry. */
575 if (frag->len > mtu ||
576 ((frag->len & 7) && frag->next) ||
577 skb_headroom(frag) < hlen)
578 goto slow_path_clean;
579
580 /* Partially cloned skb? */
581 if (skb_shared(frag))
582 goto slow_path_clean;
583
584 BUG_ON(frag->sk);
585 if (skb->sk) {
586 frag->sk = skb->sk;
587 frag->destructor = sock_wfree;
588 }
589 skb->truesize -= frag->truesize;
590 }
591
592 /* Everything is OK. Generate! */
593
594 err = 0;
595 offset = 0;
596 frag = skb_shinfo(skb)->frag_list;
597 skb_frag_list_init(skb);
598 skb->data_len = first_len - skb_headlen(skb);
599 skb->len = first_len;
600 iph->tot_len = htons(first_len);
601 iph->frag_off = htons(IP_MF);
602 ip_send_check(iph);
603
604 for (;;) {
605 /* Prepare header of the next frame,
606 * before previous one went down. */
607 if (frag) {
608 frag->ip_summed = CHECKSUM_NONE;
609 skb_reset_transport_header(frag);
610 __skb_push(frag, hlen);
611 skb_reset_network_header(frag);
612 memcpy(skb_network_header(frag), iph, hlen);
613 iph = ip_hdr(frag);
614 iph->tot_len = htons(frag->len);
615 ip_copy_metadata(frag, skb);
616 if (offset == 0)
617 ip_options_fragment(frag);
618 offset += skb->len - hlen;
619 iph->frag_off = htons(offset>>3);
620 if (frag->next)
621 iph->frag_off |= htons(IP_MF);
622 /* Ready, complete checksum */
623 ip_send_check(iph);
624 }
625
626 err = output(net, sk, skb);
627
628 if (!err)
629 IP_INC_STATS(net, IPSTATS_MIB_FRAGCREATES);
630 if (err || !frag)
631 break;
632
633 skb = frag;
634 frag = skb->next;
635 skb->next = NULL;
636 }
637
638 if (err == 0) {
639 IP_INC_STATS(net, IPSTATS_MIB_FRAGOKS);
640 return 0;
641 }
642
643 while (frag) {
644 skb = frag->next;
645 kfree_skb(frag);
646 frag = skb;
647 }
648 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
649 return err;
650
651slow_path_clean:
652 skb_walk_frags(skb, frag2) {
653 if (frag2 == frag)
654 break;
655 frag2->sk = NULL;
656 frag2->destructor = NULL;
657 skb->truesize += frag2->truesize;
658 }
659 }
660
661slow_path:
662 iph = ip_hdr(skb);
663
664 left = skb->len - hlen; /* Space per frame */
665 ptr = hlen; /* Where to start from */
666
667 ll_rs = LL_RESERVED_SPACE(rt->dst.dev);
668
669 /*
670 * Fragment the datagram.
671 */
672
673 offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3;
674 not_last_frag = iph->frag_off & htons(IP_MF);
675
676 /*
677 * Keep copying data until we run out.
678 */
679
680 while (left > 0) {
681 len = left;
682 /* IF: it doesn't fit, use 'mtu' - the data space left */
683 if (len > mtu)
684 len = mtu;
685 /* IF: we are not sending up to and including the packet end
686 then align the next start on an eight byte boundary */
687 if (len < left) {
688 len &= ~7;
689 }
690
691 /* Allocate buffer */
692 skb2 = alloc_skb(len + hlen + ll_rs, GFP_ATOMIC);
693 if (!skb2) {
694 err = -ENOMEM;
695 goto fail;
696 }
697
698 /*
699 * Set up data on packet
700 */
701
702 ip_copy_metadata(skb2, skb);
703 skb_reserve(skb2, ll_rs);
704 skb_put(skb2, len + hlen);
705 skb_reset_network_header(skb2);
706 skb2->transport_header = skb2->network_header + hlen;
707
708 /*
709 * Charge the memory for the fragment to any owner
710 * it might possess
711 */
712
713 if (skb->sk)
714 skb_set_owner_w(skb2, skb->sk);
715
716 /*
717 * Copy the packet header into the new buffer.
718 */
719
720 skb_copy_from_linear_data(skb, skb_network_header(skb2), hlen);
721
722 /*
723 * Copy a block of the IP datagram.
724 */
725 if (skb_copy_bits(skb, ptr, skb_transport_header(skb2), len))
726 BUG();
727 left -= len;
728
729 /*
730 * Fill in the new header fields.
731 */
732 iph = ip_hdr(skb2);
733 iph->frag_off = htons((offset >> 3));
734
735 if (IPCB(skb)->flags & IPSKB_FRAG_PMTU)
736 iph->frag_off |= htons(IP_DF);
737
738 /* ANK: dirty, but effective trick. Upgrade options only if
739 * the segment to be fragmented was THE FIRST (otherwise,
740 * options are already fixed) and make it ONCE
741 * on the initial skb, so that all the following fragments
742 * will inherit fixed options.
743 */
744 if (offset == 0)
745 ip_options_fragment(skb);
746
747 /*
748 * Added AC : If we are fragmenting a fragment that's not the
749 * last fragment then keep MF on each bit
750 */
751 if (left > 0 || not_last_frag)
752 iph->frag_off |= htons(IP_MF);
753 ptr += len;
754 offset += len;
755
756 /*
757 * Put this fragment into the sending queue.
758 */
759 iph->tot_len = htons(len + hlen);
760
761 ip_send_check(iph);
762
763 err = output(net, sk, skb2);
764 if (err)
765 goto fail;
766
767 IP_INC_STATS(net, IPSTATS_MIB_FRAGCREATES);
768 }
769 consume_skb(skb);
770 IP_INC_STATS(net, IPSTATS_MIB_FRAGOKS);
771 return err;
772
773fail:
774 kfree_skb(skb);
775 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
776 return err;
777}
778EXPORT_SYMBOL(ip_do_fragment);
779
780int
781ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
782{
783 struct msghdr *msg = from;
784
785 if (skb->ip_summed == CHECKSUM_PARTIAL) {
786 if (copy_from_iter(to, len, &msg->msg_iter) != len)
787 return -EFAULT;
788 } else {
789 __wsum csum = 0;
790 if (csum_and_copy_from_iter(to, len, &csum, &msg->msg_iter) != len)
791 return -EFAULT;
792 skb->csum = csum_block_add(skb->csum, csum, odd);
793 }
794 return 0;
795}
796EXPORT_SYMBOL(ip_generic_getfrag);
797
798static inline __wsum
799csum_page(struct page *page, int offset, int copy)
800{
801 char *kaddr;
802 __wsum csum;
803 kaddr = kmap(page);
804 csum = csum_partial(kaddr + offset, copy, 0);
805 kunmap(page);
806 return csum;
807}
808
809static inline int ip_ufo_append_data(struct sock *sk,
810 struct sk_buff_head *queue,
811 int getfrag(void *from, char *to, int offset, int len,
812 int odd, struct sk_buff *skb),
813 void *from, int length, int hh_len, int fragheaderlen,
814 int transhdrlen, int maxfraglen, unsigned int flags)
815{
816 struct sk_buff *skb;
817 int err;
818
819 /* There is support for UDP fragmentation offload by network
820 * device, so create one single skb packet containing complete
821 * udp datagram
822 */
823 skb = skb_peek_tail(queue);
824 if (!skb) {
825 skb = sock_alloc_send_skb(sk,
826 hh_len + fragheaderlen + transhdrlen + 20,
827 (flags & MSG_DONTWAIT), &err);
828
829 if (!skb)
830 return err;
831
832 /* reserve space for Hardware header */
833 skb_reserve(skb, hh_len);
834
835 /* create space for UDP/IP header */
836 skb_put(skb, fragheaderlen + transhdrlen);
837
838 /* initialize network header pointer */
839 skb_reset_network_header(skb);
840
841 /* initialize protocol header pointer */
842 skb->transport_header = skb->network_header + fragheaderlen;
843
844 skb->csum = 0;
845
846 __skb_queue_tail(queue, skb);
847 } else if (skb_is_gso(skb)) {
848 goto append;
849 }
850
851 skb->ip_summed = CHECKSUM_PARTIAL;
852 /* specify the length of each IP datagram fragment */
853 skb_shinfo(skb)->gso_size = maxfraglen - fragheaderlen;
854 skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
855
856append:
857 return skb_append_datato_frags(sk, skb, getfrag, from,
858 (length - transhdrlen));
859}
860
861static int __ip_append_data(struct sock *sk,
862 struct flowi4 *fl4,
863 struct sk_buff_head *queue,
864 struct inet_cork *cork,
865 struct page_frag *pfrag,
866 int getfrag(void *from, char *to, int offset,
867 int len, int odd, struct sk_buff *skb),
868 void *from, int length, int transhdrlen,
869 unsigned int flags)
870{
871 struct inet_sock *inet = inet_sk(sk);
872 struct sk_buff *skb;
873
874 struct ip_options *opt = cork->opt;
875 int hh_len;
876 int exthdrlen;
877 int mtu;
878 int copy;
879 int err;
880 int offset = 0;
881 unsigned int maxfraglen, fragheaderlen, maxnonfragsize;
882 int csummode = CHECKSUM_NONE;
883 struct rtable *rt = (struct rtable *)cork->dst;
884 u32 tskey = 0;
885
886 skb = skb_peek_tail(queue);
887
888 exthdrlen = !skb ? rt->dst.header_len : 0;
889 mtu = cork->fragsize;
890 if (cork->tx_flags & SKBTX_ANY_SW_TSTAMP &&
891 sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID)
892 tskey = sk->sk_tskey++;
893
894 hh_len = LL_RESERVED_SPACE(rt->dst.dev);
895
896 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
897 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
898 maxnonfragsize = ip_sk_ignore_df(sk) ? 0xFFFF : mtu;
899
900 if (cork->length + length > maxnonfragsize - fragheaderlen) {
901 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
902 mtu - (opt ? opt->optlen : 0));
903 return -EMSGSIZE;
904 }
905
906 /*
907 * transhdrlen > 0 means that this is the first fragment and we wish
908 * it won't be fragmented in the future.
909 */
910 if (transhdrlen &&
911 length + fragheaderlen <= mtu &&
912 rt->dst.dev->features & (NETIF_F_HW_CSUM | NETIF_F_IP_CSUM) &&
913 !(flags & MSG_MORE) &&
914 !exthdrlen)
915 csummode = CHECKSUM_PARTIAL;
916
917 cork->length += length;
918 if (((length > mtu) || (skb && skb_is_gso(skb))) &&
919 (sk->sk_protocol == IPPROTO_UDP) &&
920 (rt->dst.dev->features & NETIF_F_UFO) && !rt->dst.header_len &&
921 (sk->sk_type == SOCK_DGRAM) && !sk->sk_no_check_tx) {
922 err = ip_ufo_append_data(sk, queue, getfrag, from, length,
923 hh_len, fragheaderlen, transhdrlen,
924 maxfraglen, flags);
925 if (err)
926 goto error;
927 return 0;
928 }
929
930 /* So, what's going on in the loop below?
931 *
932 * We use calculated fragment length to generate chained skb,
933 * each of segments is IP fragment ready for sending to network after
934 * adding appropriate IP header.
935 */
936
937 if (!skb)
938 goto alloc_new_skb;
939
940 while (length > 0) {
941 /* Check if the remaining data fits into current packet. */
942 copy = mtu - skb->len;
943 if (copy < length)
944 copy = maxfraglen - skb->len;
945 if (copy <= 0) {
946 char *data;
947 unsigned int datalen;
948 unsigned int fraglen;
949 unsigned int fraggap;
950 unsigned int alloclen;
951 struct sk_buff *skb_prev;
952alloc_new_skb:
953 skb_prev = skb;
954 if (skb_prev)
955 fraggap = skb_prev->len - maxfraglen;
956 else
957 fraggap = 0;
958
959 /*
960 * If remaining data exceeds the mtu,
961 * we know we need more fragment(s).
962 */
963 datalen = length + fraggap;
964 if (datalen > mtu - fragheaderlen)
965 datalen = maxfraglen - fragheaderlen;
966 fraglen = datalen + fragheaderlen;
967
968 if ((flags & MSG_MORE) &&
969 !(rt->dst.dev->features&NETIF_F_SG))
970 alloclen = mtu;
971 else
972 alloclen = fraglen;
973
974 alloclen += exthdrlen;
975
976 /* The last fragment gets additional space at tail.
977 * Note, with MSG_MORE we overallocate on fragments,
978 * because we have no idea what fragment will be
979 * the last.
980 */
981 if (datalen == length + fraggap)
982 alloclen += rt->dst.trailer_len;
983
984 if (transhdrlen) {
985 skb = sock_alloc_send_skb(sk,
986 alloclen + hh_len + 15,
987 (flags & MSG_DONTWAIT), &err);
988 } else {
989 skb = NULL;
990 if (atomic_read(&sk->sk_wmem_alloc) <=
991 2 * sk->sk_sndbuf)
992 skb = sock_wmalloc(sk,
993 alloclen + hh_len + 15, 1,
994 sk->sk_allocation);
995 if (unlikely(!skb))
996 err = -ENOBUFS;
997 }
998 if (!skb)
999 goto error;
1000
1001 /*
1002 * Fill in the control structures
1003 */
1004 skb->ip_summed = csummode;
1005 skb->csum = 0;
1006 skb_reserve(skb, hh_len);
1007
1008 /* only the initial fragment is time stamped */
1009 skb_shinfo(skb)->tx_flags = cork->tx_flags;
1010 cork->tx_flags = 0;
1011 skb_shinfo(skb)->tskey = tskey;
1012 tskey = 0;
1013
1014 /*
1015 * Find where to start putting bytes.
1016 */
1017 data = skb_put(skb, fraglen + exthdrlen);
1018 skb_set_network_header(skb, exthdrlen);
1019 skb->transport_header = (skb->network_header +
1020 fragheaderlen);
1021 data += fragheaderlen + exthdrlen;
1022
1023 if (fraggap) {
1024 skb->csum = skb_copy_and_csum_bits(
1025 skb_prev, maxfraglen,
1026 data + transhdrlen, fraggap, 0);
1027 skb_prev->csum = csum_sub(skb_prev->csum,
1028 skb->csum);
1029 data += fraggap;
1030 pskb_trim_unique(skb_prev, maxfraglen);
1031 }
1032
1033 copy = datalen - transhdrlen - fraggap;
1034 if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) {
1035 err = -EFAULT;
1036 kfree_skb(skb);
1037 goto error;
1038 }
1039
1040 offset += copy;
1041 length -= datalen - fraggap;
1042 transhdrlen = 0;
1043 exthdrlen = 0;
1044 csummode = CHECKSUM_NONE;
1045
1046 /*
1047 * Put the packet on the pending queue.
1048 */
1049 __skb_queue_tail(queue, skb);
1050 continue;
1051 }
1052
1053 if (copy > length)
1054 copy = length;
1055
1056 if (!(rt->dst.dev->features&NETIF_F_SG)) {
1057 unsigned int off;
1058
1059 off = skb->len;
1060 if (getfrag(from, skb_put(skb, copy),
1061 offset, copy, off, skb) < 0) {
1062 __skb_trim(skb, off);
1063 err = -EFAULT;
1064 goto error;
1065 }
1066 } else {
1067 int i = skb_shinfo(skb)->nr_frags;
1068
1069 err = -ENOMEM;
1070 if (!sk_page_frag_refill(sk, pfrag))
1071 goto error;
1072
1073 if (!skb_can_coalesce(skb, i, pfrag->page,
1074 pfrag->offset)) {
1075 err = -EMSGSIZE;
1076 if (i == MAX_SKB_FRAGS)
1077 goto error;
1078
1079 __skb_fill_page_desc(skb, i, pfrag->page,
1080 pfrag->offset, 0);
1081 skb_shinfo(skb)->nr_frags = ++i;
1082 get_page(pfrag->page);
1083 }
1084 copy = min_t(int, copy, pfrag->size - pfrag->offset);
1085 if (getfrag(from,
1086 page_address(pfrag->page) + pfrag->offset,
1087 offset, copy, skb->len, skb) < 0)
1088 goto error_efault;
1089
1090 pfrag->offset += copy;
1091 skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
1092 skb->len += copy;
1093 skb->data_len += copy;
1094 skb->truesize += copy;
1095 atomic_add(copy, &sk->sk_wmem_alloc);
1096 }
1097 offset += copy;
1098 length -= copy;
1099 }
1100
1101 return 0;
1102
1103error_efault:
1104 err = -EFAULT;
1105error:
1106 cork->length -= length;
1107 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1108 return err;
1109}
1110
1111static int ip_setup_cork(struct sock *sk, struct inet_cork *cork,
1112 struct ipcm_cookie *ipc, struct rtable **rtp)
1113{
1114 struct ip_options_rcu *opt;
1115 struct rtable *rt;
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 rt = *rtp;
1133 if (unlikely(!rt))
1134 return -EFAULT;
1135 /*
1136 * We steal reference to this route, caller should not release it
1137 */
1138 *rtp = NULL;
1139 cork->fragsize = ip_sk_use_pmtu(sk) ?
1140 dst_mtu(&rt->dst) : rt->dst.dev->mtu;
1141 cork->dst = &rt->dst;
1142 cork->length = 0;
1143 cork->ttl = ipc->ttl;
1144 cork->tos = ipc->tos;
1145 cork->priority = ipc->priority;
1146 cork->tx_flags = ipc->tx_flags;
1147
1148 return 0;
1149}
1150
1151/*
1152 * ip_append_data() and ip_append_page() can make one large IP datagram
1153 * from many pieces of data. Each pieces will be holded on the socket
1154 * until ip_push_pending_frames() is called. Each piece can be a page
1155 * or non-page data.
1156 *
1157 * Not only UDP, other transport protocols - e.g. raw sockets - can use
1158 * this interface potentially.
1159 *
1160 * LATER: length must be adjusted by pad at tail, when it is required.
1161 */
1162int ip_append_data(struct sock *sk, struct flowi4 *fl4,
1163 int getfrag(void *from, char *to, int offset, int len,
1164 int odd, struct sk_buff *skb),
1165 void *from, int length, int transhdrlen,
1166 struct ipcm_cookie *ipc, struct rtable **rtp,
1167 unsigned int flags)
1168{
1169 struct inet_sock *inet = inet_sk(sk);
1170 int err;
1171
1172 if (flags&MSG_PROBE)
1173 return 0;
1174
1175 if (skb_queue_empty(&sk->sk_write_queue)) {
1176 err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp);
1177 if (err)
1178 return err;
1179 } else {
1180 transhdrlen = 0;
1181 }
1182
1183 return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base,
1184 sk_page_frag(sk), getfrag,
1185 from, length, transhdrlen, flags);
1186}
1187
1188ssize_t ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page,
1189 int offset, size_t size, int flags)
1190{
1191 struct inet_sock *inet = inet_sk(sk);
1192 struct sk_buff *skb;
1193 struct rtable *rt;
1194 struct ip_options *opt = NULL;
1195 struct inet_cork *cork;
1196 int hh_len;
1197 int mtu;
1198 int len;
1199 int err;
1200 unsigned int maxfraglen, fragheaderlen, fraggap, maxnonfragsize;
1201
1202 if (inet->hdrincl)
1203 return -EPERM;
1204
1205 if (flags&MSG_PROBE)
1206 return 0;
1207
1208 if (skb_queue_empty(&sk->sk_write_queue))
1209 return -EINVAL;
1210
1211 cork = &inet->cork.base;
1212 rt = (struct rtable *)cork->dst;
1213 if (cork->flags & IPCORK_OPT)
1214 opt = cork->opt;
1215
1216 if (!(rt->dst.dev->features&NETIF_F_SG))
1217 return -EOPNOTSUPP;
1218
1219 hh_len = LL_RESERVED_SPACE(rt->dst.dev);
1220 mtu = cork->fragsize;
1221
1222 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
1223 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
1224 maxnonfragsize = ip_sk_ignore_df(sk) ? 0xFFFF : mtu;
1225
1226 if (cork->length + size > maxnonfragsize - fragheaderlen) {
1227 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
1228 mtu - (opt ? opt->optlen : 0));
1229 return -EMSGSIZE;
1230 }
1231
1232 skb = skb_peek_tail(&sk->sk_write_queue);
1233 if (!skb)
1234 return -EINVAL;
1235
1236 if ((size + skb->len > mtu) &&
1237 (sk->sk_protocol == IPPROTO_UDP) &&
1238 (rt->dst.dev->features & NETIF_F_UFO)) {
1239 if (skb->ip_summed != CHECKSUM_PARTIAL)
1240 return -EOPNOTSUPP;
1241
1242 skb_shinfo(skb)->gso_size = mtu - fragheaderlen;
1243 skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
1244 }
1245 cork->length += size;
1246
1247 while (size > 0) {
1248 if (skb_is_gso(skb)) {
1249 len = size;
1250 } else {
1251
1252 /* Check if the remaining data fits into current packet. */
1253 len = mtu - skb->len;
1254 if (len < size)
1255 len = maxfraglen - skb->len;
1256 }
1257 if (len <= 0) {
1258 struct sk_buff *skb_prev;
1259 int alloclen;
1260
1261 skb_prev = skb;
1262 fraggap = skb_prev->len - maxfraglen;
1263
1264 alloclen = fragheaderlen + hh_len + fraggap + 15;
1265 skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation);
1266 if (unlikely(!skb)) {
1267 err = -ENOBUFS;
1268 goto error;
1269 }
1270
1271 /*
1272 * Fill in the control structures
1273 */
1274 skb->ip_summed = CHECKSUM_NONE;
1275 skb->csum = 0;
1276 skb_reserve(skb, hh_len);
1277
1278 /*
1279 * Find where to start putting bytes.
1280 */
1281 skb_put(skb, fragheaderlen + fraggap);
1282 skb_reset_network_header(skb);
1283 skb->transport_header = (skb->network_header +
1284 fragheaderlen);
1285 if (fraggap) {
1286 skb->csum = skb_copy_and_csum_bits(skb_prev,
1287 maxfraglen,
1288 skb_transport_header(skb),
1289 fraggap, 0);
1290 skb_prev->csum = csum_sub(skb_prev->csum,
1291 skb->csum);
1292 pskb_trim_unique(skb_prev, maxfraglen);
1293 }
1294
1295 /*
1296 * Put the packet on the pending queue.
1297 */
1298 __skb_queue_tail(&sk->sk_write_queue, skb);
1299 continue;
1300 }
1301
1302 if (len > size)
1303 len = size;
1304
1305 if (skb_append_pagefrags(skb, page, offset, len)) {
1306 err = -EMSGSIZE;
1307 goto error;
1308 }
1309
1310 if (skb->ip_summed == CHECKSUM_NONE) {
1311 __wsum csum;
1312 csum = csum_page(page, offset, len);
1313 skb->csum = csum_block_add(skb->csum, csum, skb->len);
1314 }
1315
1316 skb->len += len;
1317 skb->data_len += len;
1318 skb->truesize += len;
1319 atomic_add(len, &sk->sk_wmem_alloc);
1320 offset += len;
1321 size -= len;
1322 }
1323 return 0;
1324
1325error:
1326 cork->length -= size;
1327 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1328 return err;
1329}
1330
1331static void ip_cork_release(struct inet_cork *cork)
1332{
1333 cork->flags &= ~IPCORK_OPT;
1334 kfree(cork->opt);
1335 cork->opt = NULL;
1336 dst_release(cork->dst);
1337 cork->dst = NULL;
1338}
1339
1340/*
1341 * Combined all pending IP fragments on the socket as one IP datagram
1342 * and push them out.
1343 */
1344struct sk_buff *__ip_make_skb(struct sock *sk,
1345 struct flowi4 *fl4,
1346 struct sk_buff_head *queue,
1347 struct inet_cork *cork)
1348{
1349 struct sk_buff *skb, *tmp_skb;
1350 struct sk_buff **tail_skb;
1351 struct inet_sock *inet = inet_sk(sk);
1352 struct net *net = sock_net(sk);
1353 struct ip_options *opt = NULL;
1354 struct rtable *rt = (struct rtable *)cork->dst;
1355 struct iphdr *iph;
1356 __be16 df = 0;
1357 __u8 ttl;
1358
1359 skb = __skb_dequeue(queue);
1360 if (!skb)
1361 goto out;
1362 tail_skb = &(skb_shinfo(skb)->frag_list);
1363
1364 /* move skb->data to ip header from ext header */
1365 if (skb->data < skb_network_header(skb))
1366 __skb_pull(skb, skb_network_offset(skb));
1367 while ((tmp_skb = __skb_dequeue(queue)) != NULL) {
1368 __skb_pull(tmp_skb, skb_network_header_len(skb));
1369 *tail_skb = tmp_skb;
1370 tail_skb = &(tmp_skb->next);
1371 skb->len += tmp_skb->len;
1372 skb->data_len += tmp_skb->len;
1373 skb->truesize += tmp_skb->truesize;
1374 tmp_skb->destructor = NULL;
1375 tmp_skb->sk = NULL;
1376 }
1377
1378 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow
1379 * to fragment the frame generated here. No matter, what transforms
1380 * how transforms change size of the packet, it will come out.
1381 */
1382 skb->ignore_df = ip_sk_ignore_df(sk);
1383
1384 /* DF bit is set when we want to see DF on outgoing frames.
1385 * If ignore_df is set too, we still allow to fragment this frame
1386 * locally. */
1387 if (inet->pmtudisc == IP_PMTUDISC_DO ||
1388 inet->pmtudisc == IP_PMTUDISC_PROBE ||
1389 (skb->len <= dst_mtu(&rt->dst) &&
1390 ip_dont_fragment(sk, &rt->dst)))
1391 df = htons(IP_DF);
1392
1393 if (cork->flags & IPCORK_OPT)
1394 opt = cork->opt;
1395
1396 if (cork->ttl != 0)
1397 ttl = cork->ttl;
1398 else if (rt->rt_type == RTN_MULTICAST)
1399 ttl = inet->mc_ttl;
1400 else
1401 ttl = ip_select_ttl(inet, &rt->dst);
1402
1403 iph = ip_hdr(skb);
1404 iph->version = 4;
1405 iph->ihl = 5;
1406 iph->tos = (cork->tos != -1) ? cork->tos : inet->tos;
1407 iph->frag_off = df;
1408 iph->ttl = ttl;
1409 iph->protocol = sk->sk_protocol;
1410 ip_copy_addrs(iph, fl4);
1411 ip_select_ident(net, skb, sk);
1412
1413 if (opt) {
1414 iph->ihl += opt->optlen>>2;
1415 ip_options_build(skb, opt, cork->addr, rt, 0);
1416 }
1417
1418 skb->priority = (cork->tos != -1) ? cork->priority: sk->sk_priority;
1419 skb->mark = sk->sk_mark;
1420 /*
1421 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec
1422 * on dst refcount
1423 */
1424 cork->dst = NULL;
1425 skb_dst_set(skb, &rt->dst);
1426
1427 if (iph->protocol == IPPROTO_ICMP)
1428 icmp_out_count(net, ((struct icmphdr *)
1429 skb_transport_header(skb))->type);
1430
1431 ip_cork_release(cork);
1432out:
1433 return skb;
1434}
1435
1436int ip_send_skb(struct net *net, struct sk_buff *skb)
1437{
1438 int err;
1439
1440 err = ip_local_out(net, skb->sk, skb);
1441 if (err) {
1442 if (err > 0)
1443 err = net_xmit_errno(err);
1444 if (err)
1445 IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS);
1446 }
1447
1448 return err;
1449}
1450
1451int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4)
1452{
1453 struct sk_buff *skb;
1454
1455 skb = ip_finish_skb(sk, fl4);
1456 if (!skb)
1457 return 0;
1458
1459 /* Netfilter gets whole the not fragmented skb. */
1460 return ip_send_skb(sock_net(sk), skb);
1461}
1462
1463/*
1464 * Throw away all pending data on the socket.
1465 */
1466static void __ip_flush_pending_frames(struct sock *sk,
1467 struct sk_buff_head *queue,
1468 struct inet_cork *cork)
1469{
1470 struct sk_buff *skb;
1471
1472 while ((skb = __skb_dequeue_tail(queue)) != NULL)
1473 kfree_skb(skb);
1474
1475 ip_cork_release(cork);
1476}
1477
1478void ip_flush_pending_frames(struct sock *sk)
1479{
1480 __ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork.base);
1481}
1482
1483struct sk_buff *ip_make_skb(struct sock *sk,
1484 struct flowi4 *fl4,
1485 int getfrag(void *from, char *to, int offset,
1486 int len, int odd, struct sk_buff *skb),
1487 void *from, int length, int transhdrlen,
1488 struct ipcm_cookie *ipc, struct rtable **rtp,
1489 unsigned int flags)
1490{
1491 struct inet_cork cork;
1492 struct sk_buff_head queue;
1493 int err;
1494
1495 if (flags & MSG_PROBE)
1496 return NULL;
1497
1498 __skb_queue_head_init(&queue);
1499
1500 cork.flags = 0;
1501 cork.addr = 0;
1502 cork.opt = NULL;
1503 err = ip_setup_cork(sk, &cork, ipc, rtp);
1504 if (err)
1505 return ERR_PTR(err);
1506
1507 err = __ip_append_data(sk, fl4, &queue, &cork,
1508 ¤t->task_frag, getfrag,
1509 from, length, transhdrlen, flags);
1510 if (err) {
1511 __ip_flush_pending_frames(sk, &queue, &cork);
1512 return ERR_PTR(err);
1513 }
1514
1515 return __ip_make_skb(sk, fl4, &queue, &cork);
1516}
1517
1518/*
1519 * Fetch data from kernel space and fill in checksum if needed.
1520 */
1521static int ip_reply_glue_bits(void *dptr, char *to, int offset,
1522 int len, int odd, struct sk_buff *skb)
1523{
1524 __wsum csum;
1525
1526 csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0);
1527 skb->csum = csum_block_add(skb->csum, csum, odd);
1528 return 0;
1529}
1530
1531/*
1532 * Generic function to send a packet as reply to another packet.
1533 * Used to send some TCP resets/acks so far.
1534 */
1535void ip_send_unicast_reply(struct sock *sk, struct sk_buff *skb,
1536 const struct ip_options *sopt,
1537 __be32 daddr, __be32 saddr,
1538 const struct ip_reply_arg *arg,
1539 unsigned int len)
1540{
1541 struct ip_options_data replyopts;
1542 struct ipcm_cookie ipc;
1543 struct flowi4 fl4;
1544 struct rtable *rt = skb_rtable(skb);
1545 struct net *net = sock_net(sk);
1546 struct sk_buff *nskb;
1547 int err;
1548 int oif;
1549
1550 if (__ip_options_echo(&replyopts.opt.opt, skb, sopt))
1551 return;
1552
1553 ipc.addr = daddr;
1554 ipc.opt = NULL;
1555 ipc.tx_flags = 0;
1556 ipc.ttl = 0;
1557 ipc.tos = -1;
1558
1559 if (replyopts.opt.opt.optlen) {
1560 ipc.opt = &replyopts.opt;
1561
1562 if (replyopts.opt.opt.srr)
1563 daddr = replyopts.opt.opt.faddr;
1564 }
1565
1566 oif = arg->bound_dev_if;
1567 if (!oif && netif_index_is_l3_master(net, skb->skb_iif))
1568 oif = skb->skb_iif;
1569
1570 flowi4_init_output(&fl4, oif,
1571 IP4_REPLY_MARK(net, skb->mark),
1572 RT_TOS(arg->tos),
1573 RT_SCOPE_UNIVERSE, ip_hdr(skb)->protocol,
1574 ip_reply_arg_flowi_flags(arg),
1575 daddr, saddr,
1576 tcp_hdr(skb)->source, tcp_hdr(skb)->dest);
1577 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
1578 rt = ip_route_output_key(net, &fl4);
1579 if (IS_ERR(rt))
1580 return;
1581
1582 inet_sk(sk)->tos = arg->tos;
1583
1584 sk->sk_priority = skb->priority;
1585 sk->sk_protocol = ip_hdr(skb)->protocol;
1586 sk->sk_bound_dev_if = arg->bound_dev_if;
1587 sk->sk_sndbuf = sysctl_wmem_default;
1588 err = ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base,
1589 len, 0, &ipc, &rt, MSG_DONTWAIT);
1590 if (unlikely(err)) {
1591 ip_flush_pending_frames(sk);
1592 goto out;
1593 }
1594
1595 nskb = skb_peek(&sk->sk_write_queue);
1596 if (nskb) {
1597 if (arg->csumoffset >= 0)
1598 *((__sum16 *)skb_transport_header(nskb) +
1599 arg->csumoffset) = csum_fold(csum_add(nskb->csum,
1600 arg->csum));
1601 nskb->ip_summed = CHECKSUM_NONE;
1602 ip_push_pending_frames(sk, &fl4);
1603 }
1604out:
1605 ip_rt_put(rt);
1606}
1607
1608void __init ip_init(void)
1609{
1610 ip_rt_init();
1611 inet_initpeers();
1612
1613#if defined(CONFIG_IP_MULTICAST)
1614 igmp_mc_init();
1615#endif
1616}