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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 <linux/bpf-cgroup.h>
81#include <linux/igmp.h>
82#include <linux/netfilter_ipv4.h>
83#include <linux/netfilter_bridge.h>
84#include <linux/netlink.h>
85#include <linux/tcp.h>
86
87static int
88ip_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
89 unsigned int mtu,
90 int (*output)(struct net *, struct sock *, struct sk_buff *));
91
92/* Generate a checksum for an outgoing IP datagram. */
93void ip_send_check(struct iphdr *iph)
94{
95 iph->check = 0;
96 iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
97}
98EXPORT_SYMBOL(ip_send_check);
99
100int __ip_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
101{
102 struct iphdr *iph = ip_hdr(skb);
103
104 IP_INC_STATS(net, IPSTATS_MIB_OUTREQUESTS);
105
106 iph_set_totlen(iph, skb->len);
107 ip_send_check(iph);
108
109 /* if egress device is enslaved to an L3 master device pass the
110 * skb to its handler for processing
111 */
112 skb = l3mdev_ip_out(sk, skb);
113 if (unlikely(!skb))
114 return 0;
115
116 skb->protocol = htons(ETH_P_IP);
117
118 return nf_hook(NFPROTO_IPV4, NF_INET_LOCAL_OUT,
119 net, sk, skb, NULL, skb_dst(skb)->dev,
120 dst_output);
121}
122
123int ip_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
124{
125 int err;
126
127 err = __ip_local_out(net, sk, skb);
128 if (likely(err == 1))
129 err = dst_output(net, sk, skb);
130
131 return err;
132}
133EXPORT_SYMBOL_GPL(ip_local_out);
134
135static inline int ip_select_ttl(const struct inet_sock *inet,
136 const struct dst_entry *dst)
137{
138 int ttl = READ_ONCE(inet->uc_ttl);
139
140 if (ttl < 0)
141 ttl = ip4_dst_hoplimit(dst);
142 return ttl;
143}
144
145/*
146 * Add an ip header to a skbuff and send it out.
147 *
148 */
149int ip_build_and_send_pkt(struct sk_buff *skb, const struct sock *sk,
150 __be32 saddr, __be32 daddr, struct ip_options_rcu *opt,
151 u8 tos)
152{
153 const struct inet_sock *inet = inet_sk(sk);
154 struct rtable *rt = skb_rtable(skb);
155 struct net *net = sock_net(sk);
156 struct iphdr *iph;
157
158 /* Build the IP header. */
159 skb_push(skb, sizeof(struct iphdr) + (opt ? opt->opt.optlen : 0));
160 skb_reset_network_header(skb);
161 iph = ip_hdr(skb);
162 iph->version = 4;
163 iph->ihl = 5;
164 iph->tos = tos;
165 iph->ttl = ip_select_ttl(inet, &rt->dst);
166 iph->daddr = (opt && opt->opt.srr ? opt->opt.faddr : daddr);
167 iph->saddr = saddr;
168 iph->protocol = sk->sk_protocol;
169 /* Do not bother generating IPID for small packets (eg SYNACK) */
170 if (skb->len <= IPV4_MIN_MTU || ip_dont_fragment(sk, &rt->dst)) {
171 iph->frag_off = htons(IP_DF);
172 iph->id = 0;
173 } else {
174 iph->frag_off = 0;
175 /* TCP packets here are SYNACK with fat IPv4/TCP options.
176 * Avoid using the hashed IP ident generator.
177 */
178 if (sk->sk_protocol == IPPROTO_TCP)
179 iph->id = (__force __be16)get_random_u16();
180 else
181 __ip_select_ident(net, iph, 1);
182 }
183
184 if (opt && opt->opt.optlen) {
185 iph->ihl += opt->opt.optlen>>2;
186 ip_options_build(skb, &opt->opt, daddr, rt);
187 }
188
189 skb->priority = READ_ONCE(sk->sk_priority);
190 if (!skb->mark)
191 skb->mark = READ_ONCE(sk->sk_mark);
192
193 /* Send it out. */
194 return ip_local_out(net, skb->sk, skb);
195}
196EXPORT_SYMBOL_GPL(ip_build_and_send_pkt);
197
198static int ip_finish_output2(struct net *net, struct sock *sk, struct sk_buff *skb)
199{
200 struct dst_entry *dst = skb_dst(skb);
201 struct rtable *rt = dst_rtable(dst);
202 struct net_device *dev = dst->dev;
203 unsigned int hh_len = LL_RESERVED_SPACE(dev);
204 struct neighbour *neigh;
205 bool is_v6gw = false;
206
207 if (rt->rt_type == RTN_MULTICAST) {
208 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUTMCAST, skb->len);
209 } else if (rt->rt_type == RTN_BROADCAST)
210 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUTBCAST, skb->len);
211
212 /* OUTOCTETS should be counted after fragment */
213 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUT, skb->len);
214
215 if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) {
216 skb = skb_expand_head(skb, hh_len);
217 if (!skb)
218 return -ENOMEM;
219 }
220
221 if (lwtunnel_xmit_redirect(dst->lwtstate)) {
222 int res = lwtunnel_xmit(skb);
223
224 if (res != LWTUNNEL_XMIT_CONTINUE)
225 return res;
226 }
227
228 rcu_read_lock();
229 neigh = ip_neigh_for_gw(rt, skb, &is_v6gw);
230 if (!IS_ERR(neigh)) {
231 int res;
232
233 sock_confirm_neigh(skb, neigh);
234 /* if crossing protocols, can not use the cached header */
235 res = neigh_output(neigh, skb, is_v6gw);
236 rcu_read_unlock();
237 return res;
238 }
239 rcu_read_unlock();
240
241 net_dbg_ratelimited("%s: No header cache and no neighbour!\n",
242 __func__);
243 kfree_skb_reason(skb, SKB_DROP_REASON_NEIGH_CREATEFAIL);
244 return PTR_ERR(neigh);
245}
246
247static int ip_finish_output_gso(struct net *net, struct sock *sk,
248 struct sk_buff *skb, unsigned int mtu)
249{
250 struct sk_buff *segs, *nskb;
251 netdev_features_t features;
252 int ret = 0;
253
254 /* common case: seglen is <= mtu
255 */
256 if (skb_gso_validate_network_len(skb, mtu))
257 return ip_finish_output2(net, sk, skb);
258
259 /* Slowpath - GSO segment length exceeds the egress MTU.
260 *
261 * This can happen in several cases:
262 * - Forwarding of a TCP GRO skb, when DF flag is not set.
263 * - Forwarding of an skb that arrived on a virtualization interface
264 * (virtio-net/vhost/tap) with TSO/GSO size set by other network
265 * stack.
266 * - Local GSO skb transmitted on an NETIF_F_TSO tunnel stacked over an
267 * interface with a smaller MTU.
268 * - Arriving GRO skb (or GSO skb in a virtualized environment) that is
269 * bridged to a NETIF_F_TSO tunnel stacked over an interface with an
270 * insufficient MTU.
271 */
272 features = netif_skb_features(skb);
273 BUILD_BUG_ON(sizeof(*IPCB(skb)) > SKB_GSO_CB_OFFSET);
274 segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK);
275 if (IS_ERR_OR_NULL(segs)) {
276 kfree_skb(skb);
277 return -ENOMEM;
278 }
279
280 consume_skb(skb);
281
282 skb_list_walk_safe(segs, segs, nskb) {
283 int err;
284
285 skb_mark_not_on_list(segs);
286 err = ip_fragment(net, sk, segs, mtu, ip_finish_output2);
287
288 if (err && ret == 0)
289 ret = err;
290 }
291
292 return ret;
293}
294
295static int __ip_finish_output(struct net *net, struct sock *sk, struct sk_buff *skb)
296{
297 unsigned int mtu;
298
299#if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
300 /* Policy lookup after SNAT yielded a new policy */
301 if (skb_dst(skb)->xfrm) {
302 IPCB(skb)->flags |= IPSKB_REROUTED;
303 return dst_output(net, sk, skb);
304 }
305#endif
306 mtu = ip_skb_dst_mtu(sk, skb);
307 if (skb_is_gso(skb))
308 return ip_finish_output_gso(net, sk, skb, mtu);
309
310 if (skb->len > mtu || IPCB(skb)->frag_max_size)
311 return ip_fragment(net, sk, skb, mtu, ip_finish_output2);
312
313 return ip_finish_output2(net, sk, skb);
314}
315
316static int ip_finish_output(struct net *net, struct sock *sk, struct sk_buff *skb)
317{
318 int ret;
319
320 ret = BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb);
321 switch (ret) {
322 case NET_XMIT_SUCCESS:
323 return __ip_finish_output(net, sk, skb);
324 case NET_XMIT_CN:
325 return __ip_finish_output(net, sk, skb) ? : ret;
326 default:
327 kfree_skb_reason(skb, SKB_DROP_REASON_BPF_CGROUP_EGRESS);
328 return ret;
329 }
330}
331
332static int ip_mc_finish_output(struct net *net, struct sock *sk,
333 struct sk_buff *skb)
334{
335 struct rtable *new_rt;
336 bool do_cn = false;
337 int ret, err;
338
339 ret = BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb);
340 switch (ret) {
341 case NET_XMIT_CN:
342 do_cn = true;
343 fallthrough;
344 case NET_XMIT_SUCCESS:
345 break;
346 default:
347 kfree_skb_reason(skb, SKB_DROP_REASON_BPF_CGROUP_EGRESS);
348 return ret;
349 }
350
351 /* Reset rt_iif so that inet_iif() will return skb->skb_iif. Setting
352 * this to non-zero causes ipi_ifindex in in_pktinfo to be overwritten,
353 * see ipv4_pktinfo_prepare().
354 */
355 new_rt = rt_dst_clone(net->loopback_dev, skb_rtable(skb));
356 if (new_rt) {
357 new_rt->rt_iif = 0;
358 skb_dst_drop(skb);
359 skb_dst_set(skb, &new_rt->dst);
360 }
361
362 err = dev_loopback_xmit(net, sk, skb);
363 return (do_cn && err) ? ret : err;
364}
365
366int ip_mc_output(struct net *net, struct sock *sk, struct sk_buff *skb)
367{
368 struct rtable *rt = skb_rtable(skb);
369 struct net_device *dev = rt->dst.dev;
370
371 /*
372 * If the indicated interface is up and running, send the packet.
373 */
374 skb->dev = dev;
375 skb->protocol = htons(ETH_P_IP);
376
377 /*
378 * Multicasts are looped back for other local users
379 */
380
381 if (rt->rt_flags&RTCF_MULTICAST) {
382 if (sk_mc_loop(sk)
383#ifdef CONFIG_IP_MROUTE
384 /* Small optimization: do not loopback not local frames,
385 which returned after forwarding; they will be dropped
386 by ip_mr_input in any case.
387 Note, that local frames are looped back to be delivered
388 to local recipients.
389
390 This check is duplicated in ip_mr_input at the moment.
391 */
392 &&
393 ((rt->rt_flags & RTCF_LOCAL) ||
394 !(IPCB(skb)->flags & IPSKB_FORWARDED))
395#endif
396 ) {
397 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
398 if (newskb)
399 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
400 net, sk, newskb, NULL, newskb->dev,
401 ip_mc_finish_output);
402 }
403
404 /* Multicasts with ttl 0 must not go beyond the host */
405
406 if (ip_hdr(skb)->ttl == 0) {
407 kfree_skb(skb);
408 return 0;
409 }
410 }
411
412 if (rt->rt_flags&RTCF_BROADCAST) {
413 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
414 if (newskb)
415 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
416 net, sk, newskb, NULL, newskb->dev,
417 ip_mc_finish_output);
418 }
419
420 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
421 net, sk, skb, NULL, skb->dev,
422 ip_finish_output,
423 !(IPCB(skb)->flags & IPSKB_REROUTED));
424}
425
426int ip_output(struct net *net, struct sock *sk, struct sk_buff *skb)
427{
428 struct net_device *dev = skb_dst(skb)->dev, *indev = skb->dev;
429
430 skb->dev = dev;
431 skb->protocol = htons(ETH_P_IP);
432
433 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
434 net, sk, skb, indev, dev,
435 ip_finish_output,
436 !(IPCB(skb)->flags & IPSKB_REROUTED));
437}
438EXPORT_SYMBOL(ip_output);
439
440/*
441 * copy saddr and daddr, possibly using 64bit load/stores
442 * Equivalent to :
443 * iph->saddr = fl4->saddr;
444 * iph->daddr = fl4->daddr;
445 */
446static void ip_copy_addrs(struct iphdr *iph, const struct flowi4 *fl4)
447{
448 BUILD_BUG_ON(offsetof(typeof(*fl4), daddr) !=
449 offsetof(typeof(*fl4), saddr) + sizeof(fl4->saddr));
450
451 iph->saddr = fl4->saddr;
452 iph->daddr = fl4->daddr;
453}
454
455/* Note: skb->sk can be different from sk, in case of tunnels */
456int __ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl,
457 __u8 tos)
458{
459 struct inet_sock *inet = inet_sk(sk);
460 struct net *net = sock_net(sk);
461 struct ip_options_rcu *inet_opt;
462 struct flowi4 *fl4;
463 struct rtable *rt;
464 struct iphdr *iph;
465 int res;
466
467 /* Skip all of this if the packet is already routed,
468 * f.e. by something like SCTP.
469 */
470 rcu_read_lock();
471 inet_opt = rcu_dereference(inet->inet_opt);
472 fl4 = &fl->u.ip4;
473 rt = skb_rtable(skb);
474 if (rt)
475 goto packet_routed;
476
477 /* Make sure we can route this packet. */
478 rt = dst_rtable(__sk_dst_check(sk, 0));
479 if (!rt) {
480 __be32 daddr;
481
482 /* Use correct destination address if we have options. */
483 daddr = inet->inet_daddr;
484 if (inet_opt && inet_opt->opt.srr)
485 daddr = inet_opt->opt.faddr;
486
487 /* If this fails, retransmit mechanism of transport layer will
488 * keep trying until route appears or the connection times
489 * itself out.
490 */
491 rt = ip_route_output_ports(net, fl4, sk,
492 daddr, inet->inet_saddr,
493 inet->inet_dport,
494 inet->inet_sport,
495 sk->sk_protocol,
496 RT_TOS(tos),
497 sk->sk_bound_dev_if);
498 if (IS_ERR(rt))
499 goto no_route;
500 sk_setup_caps(sk, &rt->dst);
501 }
502 skb_dst_set_noref(skb, &rt->dst);
503
504packet_routed:
505 if (inet_opt && inet_opt->opt.is_strictroute && rt->rt_uses_gateway)
506 goto no_route;
507
508 /* OK, we know where to send it, allocate and build IP header. */
509 skb_push(skb, sizeof(struct iphdr) + (inet_opt ? inet_opt->opt.optlen : 0));
510 skb_reset_network_header(skb);
511 iph = ip_hdr(skb);
512 *((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (tos & 0xff));
513 if (ip_dont_fragment(sk, &rt->dst) && !skb->ignore_df)
514 iph->frag_off = htons(IP_DF);
515 else
516 iph->frag_off = 0;
517 iph->ttl = ip_select_ttl(inet, &rt->dst);
518 iph->protocol = sk->sk_protocol;
519 ip_copy_addrs(iph, fl4);
520
521 /* Transport layer set skb->h.foo itself. */
522
523 if (inet_opt && inet_opt->opt.optlen) {
524 iph->ihl += inet_opt->opt.optlen >> 2;
525 ip_options_build(skb, &inet_opt->opt, inet->inet_daddr, rt);
526 }
527
528 ip_select_ident_segs(net, skb, sk,
529 skb_shinfo(skb)->gso_segs ?: 1);
530
531 /* TODO : should we use skb->sk here instead of sk ? */
532 skb->priority = READ_ONCE(sk->sk_priority);
533 skb->mark = READ_ONCE(sk->sk_mark);
534
535 res = ip_local_out(net, sk, skb);
536 rcu_read_unlock();
537 return res;
538
539no_route:
540 rcu_read_unlock();
541 IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
542 kfree_skb_reason(skb, SKB_DROP_REASON_IP_OUTNOROUTES);
543 return -EHOSTUNREACH;
544}
545EXPORT_SYMBOL(__ip_queue_xmit);
546
547int ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl)
548{
549 return __ip_queue_xmit(sk, skb, fl, READ_ONCE(inet_sk(sk)->tos));
550}
551EXPORT_SYMBOL(ip_queue_xmit);
552
553static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from)
554{
555 to->pkt_type = from->pkt_type;
556 to->priority = from->priority;
557 to->protocol = from->protocol;
558 to->skb_iif = from->skb_iif;
559 skb_dst_drop(to);
560 skb_dst_copy(to, from);
561 to->dev = from->dev;
562 to->mark = from->mark;
563
564 skb_copy_hash(to, from);
565
566#ifdef CONFIG_NET_SCHED
567 to->tc_index = from->tc_index;
568#endif
569 nf_copy(to, from);
570 skb_ext_copy(to, from);
571#if IS_ENABLED(CONFIG_IP_VS)
572 to->ipvs_property = from->ipvs_property;
573#endif
574 skb_copy_secmark(to, from);
575}
576
577static int ip_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
578 unsigned int mtu,
579 int (*output)(struct net *, struct sock *, struct sk_buff *))
580{
581 struct iphdr *iph = ip_hdr(skb);
582
583 if ((iph->frag_off & htons(IP_DF)) == 0)
584 return ip_do_fragment(net, sk, skb, output);
585
586 if (unlikely(!skb->ignore_df ||
587 (IPCB(skb)->frag_max_size &&
588 IPCB(skb)->frag_max_size > mtu))) {
589 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
590 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
591 htonl(mtu));
592 kfree_skb(skb);
593 return -EMSGSIZE;
594 }
595
596 return ip_do_fragment(net, sk, skb, output);
597}
598
599void ip_fraglist_init(struct sk_buff *skb, struct iphdr *iph,
600 unsigned int hlen, struct ip_fraglist_iter *iter)
601{
602 unsigned int first_len = skb_pagelen(skb);
603
604 iter->frag = skb_shinfo(skb)->frag_list;
605 skb_frag_list_init(skb);
606
607 iter->offset = 0;
608 iter->iph = iph;
609 iter->hlen = hlen;
610
611 skb->data_len = first_len - skb_headlen(skb);
612 skb->len = first_len;
613 iph->tot_len = htons(first_len);
614 iph->frag_off = htons(IP_MF);
615 ip_send_check(iph);
616}
617EXPORT_SYMBOL(ip_fraglist_init);
618
619void ip_fraglist_prepare(struct sk_buff *skb, struct ip_fraglist_iter *iter)
620{
621 unsigned int hlen = iter->hlen;
622 struct iphdr *iph = iter->iph;
623 struct sk_buff *frag;
624
625 frag = iter->frag;
626 frag->ip_summed = CHECKSUM_NONE;
627 skb_reset_transport_header(frag);
628 __skb_push(frag, hlen);
629 skb_reset_network_header(frag);
630 memcpy(skb_network_header(frag), iph, hlen);
631 iter->iph = ip_hdr(frag);
632 iph = iter->iph;
633 iph->tot_len = htons(frag->len);
634 ip_copy_metadata(frag, skb);
635 iter->offset += skb->len - hlen;
636 iph->frag_off = htons(iter->offset >> 3);
637 if (frag->next)
638 iph->frag_off |= htons(IP_MF);
639 /* Ready, complete checksum */
640 ip_send_check(iph);
641}
642EXPORT_SYMBOL(ip_fraglist_prepare);
643
644void ip_frag_init(struct sk_buff *skb, unsigned int hlen,
645 unsigned int ll_rs, unsigned int mtu, bool DF,
646 struct ip_frag_state *state)
647{
648 struct iphdr *iph = ip_hdr(skb);
649
650 state->DF = DF;
651 state->hlen = hlen;
652 state->ll_rs = ll_rs;
653 state->mtu = mtu;
654
655 state->left = skb->len - hlen; /* Space per frame */
656 state->ptr = hlen; /* Where to start from */
657
658 state->offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3;
659 state->not_last_frag = iph->frag_off & htons(IP_MF);
660}
661EXPORT_SYMBOL(ip_frag_init);
662
663static void ip_frag_ipcb(struct sk_buff *from, struct sk_buff *to,
664 bool first_frag)
665{
666 /* Copy the flags to each fragment. */
667 IPCB(to)->flags = IPCB(from)->flags;
668
669 /* ANK: dirty, but effective trick. Upgrade options only if
670 * the segment to be fragmented was THE FIRST (otherwise,
671 * options are already fixed) and make it ONCE
672 * on the initial skb, so that all the following fragments
673 * will inherit fixed options.
674 */
675 if (first_frag)
676 ip_options_fragment(from);
677}
678
679struct sk_buff *ip_frag_next(struct sk_buff *skb, struct ip_frag_state *state)
680{
681 unsigned int len = state->left;
682 struct sk_buff *skb2;
683 struct iphdr *iph;
684
685 /* IF: it doesn't fit, use 'mtu' - the data space left */
686 if (len > state->mtu)
687 len = state->mtu;
688 /* IF: we are not sending up to and including the packet end
689 then align the next start on an eight byte boundary */
690 if (len < state->left) {
691 len &= ~7;
692 }
693
694 /* Allocate buffer */
695 skb2 = alloc_skb(len + state->hlen + state->ll_rs, GFP_ATOMIC);
696 if (!skb2)
697 return ERR_PTR(-ENOMEM);
698
699 /*
700 * Set up data on packet
701 */
702
703 ip_copy_metadata(skb2, skb);
704 skb_reserve(skb2, state->ll_rs);
705 skb_put(skb2, len + state->hlen);
706 skb_reset_network_header(skb2);
707 skb2->transport_header = skb2->network_header + state->hlen;
708
709 /*
710 * Charge the memory for the fragment to any owner
711 * it might possess
712 */
713
714 if (skb->sk)
715 skb_set_owner_w(skb2, skb->sk);
716
717 /*
718 * Copy the packet header into the new buffer.
719 */
720
721 skb_copy_from_linear_data(skb, skb_network_header(skb2), state->hlen);
722
723 /*
724 * Copy a block of the IP datagram.
725 */
726 if (skb_copy_bits(skb, state->ptr, skb_transport_header(skb2), len))
727 BUG();
728 state->left -= len;
729
730 /*
731 * Fill in the new header fields.
732 */
733 iph = ip_hdr(skb2);
734 iph->frag_off = htons((state->offset >> 3));
735 if (state->DF)
736 iph->frag_off |= htons(IP_DF);
737
738 /*
739 * Added AC : If we are fragmenting a fragment that's not the
740 * last fragment then keep MF on each bit
741 */
742 if (state->left > 0 || state->not_last_frag)
743 iph->frag_off |= htons(IP_MF);
744 state->ptr += len;
745 state->offset += len;
746
747 iph->tot_len = htons(len + state->hlen);
748
749 ip_send_check(iph);
750
751 return skb2;
752}
753EXPORT_SYMBOL(ip_frag_next);
754
755/*
756 * This IP datagram is too large to be sent in one piece. Break it up into
757 * smaller pieces (each of size equal to IP header plus
758 * a block of the data of the original IP data part) that will yet fit in a
759 * single device frame, and queue such a frame for sending.
760 */
761
762int ip_do_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
763 int (*output)(struct net *, struct sock *, struct sk_buff *))
764{
765 struct iphdr *iph;
766 struct sk_buff *skb2;
767 bool mono_delivery_time = skb->mono_delivery_time;
768 struct rtable *rt = skb_rtable(skb);
769 unsigned int mtu, hlen, ll_rs;
770 struct ip_fraglist_iter iter;
771 ktime_t tstamp = skb->tstamp;
772 struct ip_frag_state state;
773 int err = 0;
774
775 /* for offloaded checksums cleanup checksum before fragmentation */
776 if (skb->ip_summed == CHECKSUM_PARTIAL &&
777 (err = skb_checksum_help(skb)))
778 goto fail;
779
780 /*
781 * Point into the IP datagram header.
782 */
783
784 iph = ip_hdr(skb);
785
786 mtu = ip_skb_dst_mtu(sk, skb);
787 if (IPCB(skb)->frag_max_size && IPCB(skb)->frag_max_size < mtu)
788 mtu = IPCB(skb)->frag_max_size;
789
790 /*
791 * Setup starting values.
792 */
793
794 hlen = iph->ihl * 4;
795 mtu = mtu - hlen; /* Size of data space */
796 IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE;
797 ll_rs = LL_RESERVED_SPACE(rt->dst.dev);
798
799 /* When frag_list is given, use it. First, check its validity:
800 * some transformers could create wrong frag_list or break existing
801 * one, it is not prohibited. In this case fall back to copying.
802 *
803 * LATER: this step can be merged to real generation of fragments,
804 * we can switch to copy when see the first bad fragment.
805 */
806 if (skb_has_frag_list(skb)) {
807 struct sk_buff *frag, *frag2;
808 unsigned int first_len = skb_pagelen(skb);
809
810 if (first_len - hlen > mtu ||
811 ((first_len - hlen) & 7) ||
812 ip_is_fragment(iph) ||
813 skb_cloned(skb) ||
814 skb_headroom(skb) < ll_rs)
815 goto slow_path;
816
817 skb_walk_frags(skb, frag) {
818 /* Correct geometry. */
819 if (frag->len > mtu ||
820 ((frag->len & 7) && frag->next) ||
821 skb_headroom(frag) < hlen + ll_rs)
822 goto slow_path_clean;
823
824 /* Partially cloned skb? */
825 if (skb_shared(frag))
826 goto slow_path_clean;
827
828 BUG_ON(frag->sk);
829 if (skb->sk) {
830 frag->sk = skb->sk;
831 frag->destructor = sock_wfree;
832 }
833 skb->truesize -= frag->truesize;
834 }
835
836 /* Everything is OK. Generate! */
837 ip_fraglist_init(skb, iph, hlen, &iter);
838
839 for (;;) {
840 /* Prepare header of the next frame,
841 * before previous one went down. */
842 if (iter.frag) {
843 bool first_frag = (iter.offset == 0);
844
845 IPCB(iter.frag)->flags = IPCB(skb)->flags;
846 ip_fraglist_prepare(skb, &iter);
847 if (first_frag && IPCB(skb)->opt.optlen) {
848 /* ipcb->opt is not populated for frags
849 * coming from __ip_make_skb(),
850 * ip_options_fragment() needs optlen
851 */
852 IPCB(iter.frag)->opt.optlen =
853 IPCB(skb)->opt.optlen;
854 ip_options_fragment(iter.frag);
855 ip_send_check(iter.iph);
856 }
857 }
858
859 skb_set_delivery_time(skb, tstamp, mono_delivery_time);
860 err = output(net, sk, skb);
861
862 if (!err)
863 IP_INC_STATS(net, IPSTATS_MIB_FRAGCREATES);
864 if (err || !iter.frag)
865 break;
866
867 skb = ip_fraglist_next(&iter);
868 }
869
870 if (err == 0) {
871 IP_INC_STATS(net, IPSTATS_MIB_FRAGOKS);
872 return 0;
873 }
874
875 kfree_skb_list(iter.frag);
876
877 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
878 return err;
879
880slow_path_clean:
881 skb_walk_frags(skb, frag2) {
882 if (frag2 == frag)
883 break;
884 frag2->sk = NULL;
885 frag2->destructor = NULL;
886 skb->truesize += frag2->truesize;
887 }
888 }
889
890slow_path:
891 /*
892 * Fragment the datagram.
893 */
894
895 ip_frag_init(skb, hlen, ll_rs, mtu, IPCB(skb)->flags & IPSKB_FRAG_PMTU,
896 &state);
897
898 /*
899 * Keep copying data until we run out.
900 */
901
902 while (state.left > 0) {
903 bool first_frag = (state.offset == 0);
904
905 skb2 = ip_frag_next(skb, &state);
906 if (IS_ERR(skb2)) {
907 err = PTR_ERR(skb2);
908 goto fail;
909 }
910 ip_frag_ipcb(skb, skb2, first_frag);
911
912 /*
913 * Put this fragment into the sending queue.
914 */
915 skb_set_delivery_time(skb2, tstamp, mono_delivery_time);
916 err = output(net, sk, skb2);
917 if (err)
918 goto fail;
919
920 IP_INC_STATS(net, IPSTATS_MIB_FRAGCREATES);
921 }
922 consume_skb(skb);
923 IP_INC_STATS(net, IPSTATS_MIB_FRAGOKS);
924 return err;
925
926fail:
927 kfree_skb(skb);
928 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
929 return err;
930}
931EXPORT_SYMBOL(ip_do_fragment);
932
933int
934ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
935{
936 struct msghdr *msg = from;
937
938 if (skb->ip_summed == CHECKSUM_PARTIAL) {
939 if (!copy_from_iter_full(to, len, &msg->msg_iter))
940 return -EFAULT;
941 } else {
942 __wsum csum = 0;
943 if (!csum_and_copy_from_iter_full(to, len, &csum, &msg->msg_iter))
944 return -EFAULT;
945 skb->csum = csum_block_add(skb->csum, csum, odd);
946 }
947 return 0;
948}
949EXPORT_SYMBOL(ip_generic_getfrag);
950
951static int __ip_append_data(struct sock *sk,
952 struct flowi4 *fl4,
953 struct sk_buff_head *queue,
954 struct inet_cork *cork,
955 struct page_frag *pfrag,
956 int getfrag(void *from, char *to, int offset,
957 int len, int odd, struct sk_buff *skb),
958 void *from, int length, int transhdrlen,
959 unsigned int flags)
960{
961 struct inet_sock *inet = inet_sk(sk);
962 struct ubuf_info *uarg = NULL;
963 struct sk_buff *skb;
964 struct ip_options *opt = cork->opt;
965 int hh_len;
966 int exthdrlen;
967 int mtu;
968 int copy;
969 int err;
970 int offset = 0;
971 bool zc = false;
972 unsigned int maxfraglen, fragheaderlen, maxnonfragsize;
973 int csummode = CHECKSUM_NONE;
974 struct rtable *rt = dst_rtable(cork->dst);
975 bool paged, hold_tskey, extra_uref = false;
976 unsigned int wmem_alloc_delta = 0;
977 u32 tskey = 0;
978
979 skb = skb_peek_tail(queue);
980
981 exthdrlen = !skb ? rt->dst.header_len : 0;
982 mtu = cork->gso_size ? IP_MAX_MTU : cork->fragsize;
983 paged = !!cork->gso_size;
984
985 hh_len = LL_RESERVED_SPACE(rt->dst.dev);
986
987 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
988 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
989 maxnonfragsize = ip_sk_ignore_df(sk) ? IP_MAX_MTU : mtu;
990
991 if (cork->length + length > maxnonfragsize - fragheaderlen) {
992 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
993 mtu - (opt ? opt->optlen : 0));
994 return -EMSGSIZE;
995 }
996
997 /*
998 * transhdrlen > 0 means that this is the first fragment and we wish
999 * it won't be fragmented in the future.
1000 */
1001 if (transhdrlen &&
1002 length + fragheaderlen <= mtu &&
1003 rt->dst.dev->features & (NETIF_F_HW_CSUM | NETIF_F_IP_CSUM) &&
1004 (!(flags & MSG_MORE) || cork->gso_size) &&
1005 (!exthdrlen || (rt->dst.dev->features & NETIF_F_HW_ESP_TX_CSUM)))
1006 csummode = CHECKSUM_PARTIAL;
1007
1008 if ((flags & MSG_ZEROCOPY) && length) {
1009 struct msghdr *msg = from;
1010
1011 if (getfrag == ip_generic_getfrag && msg->msg_ubuf) {
1012 if (skb_zcopy(skb) && msg->msg_ubuf != skb_zcopy(skb))
1013 return -EINVAL;
1014
1015 /* Leave uarg NULL if can't zerocopy, callers should
1016 * be able to handle it.
1017 */
1018 if ((rt->dst.dev->features & NETIF_F_SG) &&
1019 csummode == CHECKSUM_PARTIAL) {
1020 paged = true;
1021 zc = true;
1022 uarg = msg->msg_ubuf;
1023 }
1024 } else if (sock_flag(sk, SOCK_ZEROCOPY)) {
1025 uarg = msg_zerocopy_realloc(sk, length, skb_zcopy(skb));
1026 if (!uarg)
1027 return -ENOBUFS;
1028 extra_uref = !skb_zcopy(skb); /* only ref on new uarg */
1029 if (rt->dst.dev->features & NETIF_F_SG &&
1030 csummode == CHECKSUM_PARTIAL) {
1031 paged = true;
1032 zc = true;
1033 } else {
1034 uarg_to_msgzc(uarg)->zerocopy = 0;
1035 skb_zcopy_set(skb, uarg, &extra_uref);
1036 }
1037 }
1038 } else if ((flags & MSG_SPLICE_PAGES) && length) {
1039 if (inet_test_bit(HDRINCL, sk))
1040 return -EPERM;
1041 if (rt->dst.dev->features & NETIF_F_SG &&
1042 getfrag == ip_generic_getfrag)
1043 /* We need an empty buffer to attach stuff to */
1044 paged = true;
1045 else
1046 flags &= ~MSG_SPLICE_PAGES;
1047 }
1048
1049 cork->length += length;
1050
1051 hold_tskey = cork->tx_flags & SKBTX_ANY_TSTAMP &&
1052 READ_ONCE(sk->sk_tsflags) & SOF_TIMESTAMPING_OPT_ID;
1053 if (hold_tskey)
1054 tskey = atomic_inc_return(&sk->sk_tskey) - 1;
1055
1056 /* So, what's going on in the loop below?
1057 *
1058 * We use calculated fragment length to generate chained skb,
1059 * each of segments is IP fragment ready for sending to network after
1060 * adding appropriate IP header.
1061 */
1062
1063 if (!skb)
1064 goto alloc_new_skb;
1065
1066 while (length > 0) {
1067 /* Check if the remaining data fits into current packet. */
1068 copy = mtu - skb->len;
1069 if (copy < length)
1070 copy = maxfraglen - skb->len;
1071 if (copy <= 0) {
1072 char *data;
1073 unsigned int datalen;
1074 unsigned int fraglen;
1075 unsigned int fraggap;
1076 unsigned int alloclen, alloc_extra;
1077 unsigned int pagedlen;
1078 struct sk_buff *skb_prev;
1079alloc_new_skb:
1080 skb_prev = skb;
1081 if (skb_prev)
1082 fraggap = skb_prev->len - maxfraglen;
1083 else
1084 fraggap = 0;
1085
1086 /*
1087 * If remaining data exceeds the mtu,
1088 * we know we need more fragment(s).
1089 */
1090 datalen = length + fraggap;
1091 if (datalen > mtu - fragheaderlen)
1092 datalen = maxfraglen - fragheaderlen;
1093 fraglen = datalen + fragheaderlen;
1094 pagedlen = 0;
1095
1096 alloc_extra = hh_len + 15;
1097 alloc_extra += exthdrlen;
1098
1099 /* The last fragment gets additional space at tail.
1100 * Note, with MSG_MORE we overallocate on fragments,
1101 * because we have no idea what fragment will be
1102 * the last.
1103 */
1104 if (datalen == length + fraggap)
1105 alloc_extra += rt->dst.trailer_len;
1106
1107 if ((flags & MSG_MORE) &&
1108 !(rt->dst.dev->features&NETIF_F_SG))
1109 alloclen = mtu;
1110 else if (!paged &&
1111 (fraglen + alloc_extra < SKB_MAX_ALLOC ||
1112 !(rt->dst.dev->features & NETIF_F_SG)))
1113 alloclen = fraglen;
1114 else {
1115 alloclen = fragheaderlen + transhdrlen;
1116 pagedlen = datalen - transhdrlen;
1117 }
1118
1119 alloclen += alloc_extra;
1120
1121 if (transhdrlen) {
1122 skb = sock_alloc_send_skb(sk, alloclen,
1123 (flags & MSG_DONTWAIT), &err);
1124 } else {
1125 skb = NULL;
1126 if (refcount_read(&sk->sk_wmem_alloc) + wmem_alloc_delta <=
1127 2 * sk->sk_sndbuf)
1128 skb = alloc_skb(alloclen,
1129 sk->sk_allocation);
1130 if (unlikely(!skb))
1131 err = -ENOBUFS;
1132 }
1133 if (!skb)
1134 goto error;
1135
1136 /*
1137 * Fill in the control structures
1138 */
1139 skb->ip_summed = csummode;
1140 skb->csum = 0;
1141 skb_reserve(skb, hh_len);
1142
1143 /*
1144 * Find where to start putting bytes.
1145 */
1146 data = skb_put(skb, fraglen + exthdrlen - pagedlen);
1147 skb_set_network_header(skb, exthdrlen);
1148 skb->transport_header = (skb->network_header +
1149 fragheaderlen);
1150 data += fragheaderlen + exthdrlen;
1151
1152 if (fraggap) {
1153 skb->csum = skb_copy_and_csum_bits(
1154 skb_prev, maxfraglen,
1155 data + transhdrlen, fraggap);
1156 skb_prev->csum = csum_sub(skb_prev->csum,
1157 skb->csum);
1158 data += fraggap;
1159 pskb_trim_unique(skb_prev, maxfraglen);
1160 }
1161
1162 copy = datalen - transhdrlen - fraggap - pagedlen;
1163 /* [!] NOTE: copy will be negative if pagedlen>0
1164 * because then the equation reduces to -fraggap.
1165 */
1166 if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) {
1167 err = -EFAULT;
1168 kfree_skb(skb);
1169 goto error;
1170 } else if (flags & MSG_SPLICE_PAGES) {
1171 copy = 0;
1172 }
1173
1174 offset += copy;
1175 length -= copy + transhdrlen;
1176 transhdrlen = 0;
1177 exthdrlen = 0;
1178 csummode = CHECKSUM_NONE;
1179
1180 /* only the initial fragment is time stamped */
1181 skb_shinfo(skb)->tx_flags = cork->tx_flags;
1182 cork->tx_flags = 0;
1183 skb_shinfo(skb)->tskey = tskey;
1184 tskey = 0;
1185 skb_zcopy_set(skb, uarg, &extra_uref);
1186
1187 if ((flags & MSG_CONFIRM) && !skb_prev)
1188 skb_set_dst_pending_confirm(skb, 1);
1189
1190 /*
1191 * Put the packet on the pending queue.
1192 */
1193 if (!skb->destructor) {
1194 skb->destructor = sock_wfree;
1195 skb->sk = sk;
1196 wmem_alloc_delta += skb->truesize;
1197 }
1198 __skb_queue_tail(queue, skb);
1199 continue;
1200 }
1201
1202 if (copy > length)
1203 copy = length;
1204
1205 if (!(rt->dst.dev->features&NETIF_F_SG) &&
1206 skb_tailroom(skb) >= copy) {
1207 unsigned int off;
1208
1209 off = skb->len;
1210 if (getfrag(from, skb_put(skb, copy),
1211 offset, copy, off, skb) < 0) {
1212 __skb_trim(skb, off);
1213 err = -EFAULT;
1214 goto error;
1215 }
1216 } else if (flags & MSG_SPLICE_PAGES) {
1217 struct msghdr *msg = from;
1218
1219 err = -EIO;
1220 if (WARN_ON_ONCE(copy > msg->msg_iter.count))
1221 goto error;
1222
1223 err = skb_splice_from_iter(skb, &msg->msg_iter, copy,
1224 sk->sk_allocation);
1225 if (err < 0)
1226 goto error;
1227 copy = err;
1228 wmem_alloc_delta += copy;
1229 } else if (!zc) {
1230 int i = skb_shinfo(skb)->nr_frags;
1231
1232 err = -ENOMEM;
1233 if (!sk_page_frag_refill(sk, pfrag))
1234 goto error;
1235
1236 skb_zcopy_downgrade_managed(skb);
1237 if (!skb_can_coalesce(skb, i, pfrag->page,
1238 pfrag->offset)) {
1239 err = -EMSGSIZE;
1240 if (i == MAX_SKB_FRAGS)
1241 goto error;
1242
1243 __skb_fill_page_desc(skb, i, pfrag->page,
1244 pfrag->offset, 0);
1245 skb_shinfo(skb)->nr_frags = ++i;
1246 get_page(pfrag->page);
1247 }
1248 copy = min_t(int, copy, pfrag->size - pfrag->offset);
1249 if (getfrag(from,
1250 page_address(pfrag->page) + pfrag->offset,
1251 offset, copy, skb->len, skb) < 0)
1252 goto error_efault;
1253
1254 pfrag->offset += copy;
1255 skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
1256 skb_len_add(skb, copy);
1257 wmem_alloc_delta += copy;
1258 } else {
1259 err = skb_zerocopy_iter_dgram(skb, from, copy);
1260 if (err < 0)
1261 goto error;
1262 }
1263 offset += copy;
1264 length -= copy;
1265 }
1266
1267 if (wmem_alloc_delta)
1268 refcount_add(wmem_alloc_delta, &sk->sk_wmem_alloc);
1269 return 0;
1270
1271error_efault:
1272 err = -EFAULT;
1273error:
1274 net_zcopy_put_abort(uarg, extra_uref);
1275 cork->length -= length;
1276 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1277 refcount_add(wmem_alloc_delta, &sk->sk_wmem_alloc);
1278 if (hold_tskey)
1279 atomic_dec(&sk->sk_tskey);
1280 return err;
1281}
1282
1283static int ip_setup_cork(struct sock *sk, struct inet_cork *cork,
1284 struct ipcm_cookie *ipc, struct rtable **rtp)
1285{
1286 struct ip_options_rcu *opt;
1287 struct rtable *rt;
1288
1289 rt = *rtp;
1290 if (unlikely(!rt))
1291 return -EFAULT;
1292
1293 cork->fragsize = ip_sk_use_pmtu(sk) ?
1294 dst_mtu(&rt->dst) : READ_ONCE(rt->dst.dev->mtu);
1295
1296 if (!inetdev_valid_mtu(cork->fragsize))
1297 return -ENETUNREACH;
1298
1299 /*
1300 * setup for corking.
1301 */
1302 opt = ipc->opt;
1303 if (opt) {
1304 if (!cork->opt) {
1305 cork->opt = kmalloc(sizeof(struct ip_options) + 40,
1306 sk->sk_allocation);
1307 if (unlikely(!cork->opt))
1308 return -ENOBUFS;
1309 }
1310 memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen);
1311 cork->flags |= IPCORK_OPT;
1312 cork->addr = ipc->addr;
1313 }
1314
1315 cork->gso_size = ipc->gso_size;
1316
1317 cork->dst = &rt->dst;
1318 /* We stole this route, caller should not release it. */
1319 *rtp = NULL;
1320
1321 cork->length = 0;
1322 cork->ttl = ipc->ttl;
1323 cork->tos = ipc->tos;
1324 cork->mark = ipc->sockc.mark;
1325 cork->priority = ipc->priority;
1326 cork->transmit_time = ipc->sockc.transmit_time;
1327 cork->tx_flags = 0;
1328 sock_tx_timestamp(sk, ipc->sockc.tsflags, &cork->tx_flags);
1329
1330 return 0;
1331}
1332
1333/*
1334 * ip_append_data() can make one large IP datagram from many pieces of
1335 * data. Each piece will be held on the socket until
1336 * ip_push_pending_frames() is called. Each piece can be a page or
1337 * non-page data.
1338 *
1339 * Not only UDP, other transport protocols - e.g. raw sockets - can use
1340 * this interface potentially.
1341 *
1342 * LATER: length must be adjusted by pad at tail, when it is required.
1343 */
1344int ip_append_data(struct sock *sk, struct flowi4 *fl4,
1345 int getfrag(void *from, char *to, int offset, int len,
1346 int odd, struct sk_buff *skb),
1347 void *from, int length, int transhdrlen,
1348 struct ipcm_cookie *ipc, struct rtable **rtp,
1349 unsigned int flags)
1350{
1351 struct inet_sock *inet = inet_sk(sk);
1352 int err;
1353
1354 if (flags&MSG_PROBE)
1355 return 0;
1356
1357 if (skb_queue_empty(&sk->sk_write_queue)) {
1358 err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp);
1359 if (err)
1360 return err;
1361 } else {
1362 transhdrlen = 0;
1363 }
1364
1365 return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base,
1366 sk_page_frag(sk), getfrag,
1367 from, length, transhdrlen, flags);
1368}
1369
1370static void ip_cork_release(struct inet_cork *cork)
1371{
1372 cork->flags &= ~IPCORK_OPT;
1373 kfree(cork->opt);
1374 cork->opt = NULL;
1375 dst_release(cork->dst);
1376 cork->dst = NULL;
1377}
1378
1379/*
1380 * Combined all pending IP fragments on the socket as one IP datagram
1381 * and push them out.
1382 */
1383struct sk_buff *__ip_make_skb(struct sock *sk,
1384 struct flowi4 *fl4,
1385 struct sk_buff_head *queue,
1386 struct inet_cork *cork)
1387{
1388 struct sk_buff *skb, *tmp_skb;
1389 struct sk_buff **tail_skb;
1390 struct inet_sock *inet = inet_sk(sk);
1391 struct net *net = sock_net(sk);
1392 struct ip_options *opt = NULL;
1393 struct rtable *rt = dst_rtable(cork->dst);
1394 struct iphdr *iph;
1395 u8 pmtudisc, ttl;
1396 __be16 df = 0;
1397
1398 skb = __skb_dequeue(queue);
1399 if (!skb)
1400 goto out;
1401 tail_skb = &(skb_shinfo(skb)->frag_list);
1402
1403 /* move skb->data to ip header from ext header */
1404 if (skb->data < skb_network_header(skb))
1405 __skb_pull(skb, skb_network_offset(skb));
1406 while ((tmp_skb = __skb_dequeue(queue)) != NULL) {
1407 __skb_pull(tmp_skb, skb_network_header_len(skb));
1408 *tail_skb = tmp_skb;
1409 tail_skb = &(tmp_skb->next);
1410 skb->len += tmp_skb->len;
1411 skb->data_len += tmp_skb->len;
1412 skb->truesize += tmp_skb->truesize;
1413 tmp_skb->destructor = NULL;
1414 tmp_skb->sk = NULL;
1415 }
1416
1417 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow
1418 * to fragment the frame generated here. No matter, what transforms
1419 * how transforms change size of the packet, it will come out.
1420 */
1421 skb->ignore_df = ip_sk_ignore_df(sk);
1422
1423 /* DF bit is set when we want to see DF on outgoing frames.
1424 * If ignore_df is set too, we still allow to fragment this frame
1425 * locally. */
1426 pmtudisc = READ_ONCE(inet->pmtudisc);
1427 if (pmtudisc == IP_PMTUDISC_DO ||
1428 pmtudisc == IP_PMTUDISC_PROBE ||
1429 (skb->len <= dst_mtu(&rt->dst) &&
1430 ip_dont_fragment(sk, &rt->dst)))
1431 df = htons(IP_DF);
1432
1433 if (cork->flags & IPCORK_OPT)
1434 opt = cork->opt;
1435
1436 if (cork->ttl != 0)
1437 ttl = cork->ttl;
1438 else if (rt->rt_type == RTN_MULTICAST)
1439 ttl = READ_ONCE(inet->mc_ttl);
1440 else
1441 ttl = ip_select_ttl(inet, &rt->dst);
1442
1443 iph = ip_hdr(skb);
1444 iph->version = 4;
1445 iph->ihl = 5;
1446 iph->tos = (cork->tos != -1) ? cork->tos : READ_ONCE(inet->tos);
1447 iph->frag_off = df;
1448 iph->ttl = ttl;
1449 iph->protocol = sk->sk_protocol;
1450 ip_copy_addrs(iph, fl4);
1451 ip_select_ident(net, skb, sk);
1452
1453 if (opt) {
1454 iph->ihl += opt->optlen >> 2;
1455 ip_options_build(skb, opt, cork->addr, rt);
1456 }
1457
1458 skb->priority = (cork->tos != -1) ? cork->priority: READ_ONCE(sk->sk_priority);
1459 skb->mark = cork->mark;
1460 skb->tstamp = cork->transmit_time;
1461 /*
1462 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec
1463 * on dst refcount
1464 */
1465 cork->dst = NULL;
1466 skb_dst_set(skb, &rt->dst);
1467
1468 if (iph->protocol == IPPROTO_ICMP) {
1469 u8 icmp_type;
1470
1471 /* For such sockets, transhdrlen is zero when do ip_append_data(),
1472 * so icmphdr does not in skb linear region and can not get icmp_type
1473 * by icmp_hdr(skb)->type.
1474 */
1475 if (sk->sk_type == SOCK_RAW &&
1476 !(fl4->flowi4_flags & FLOWI_FLAG_KNOWN_NH))
1477 icmp_type = fl4->fl4_icmp_type;
1478 else
1479 icmp_type = icmp_hdr(skb)->type;
1480 icmp_out_count(net, icmp_type);
1481 }
1482
1483 ip_cork_release(cork);
1484out:
1485 return skb;
1486}
1487
1488int ip_send_skb(struct net *net, struct sk_buff *skb)
1489{
1490 int err;
1491
1492 err = ip_local_out(net, skb->sk, skb);
1493 if (err) {
1494 if (err > 0)
1495 err = net_xmit_errno(err);
1496 if (err)
1497 IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS);
1498 }
1499
1500 return err;
1501}
1502
1503int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4)
1504{
1505 struct sk_buff *skb;
1506
1507 skb = ip_finish_skb(sk, fl4);
1508 if (!skb)
1509 return 0;
1510
1511 /* Netfilter gets whole the not fragmented skb. */
1512 return ip_send_skb(sock_net(sk), skb);
1513}
1514
1515/*
1516 * Throw away all pending data on the socket.
1517 */
1518static void __ip_flush_pending_frames(struct sock *sk,
1519 struct sk_buff_head *queue,
1520 struct inet_cork *cork)
1521{
1522 struct sk_buff *skb;
1523
1524 while ((skb = __skb_dequeue_tail(queue)) != NULL)
1525 kfree_skb(skb);
1526
1527 ip_cork_release(cork);
1528}
1529
1530void ip_flush_pending_frames(struct sock *sk)
1531{
1532 __ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork.base);
1533}
1534
1535struct sk_buff *ip_make_skb(struct sock *sk,
1536 struct flowi4 *fl4,
1537 int getfrag(void *from, char *to, int offset,
1538 int len, int odd, struct sk_buff *skb),
1539 void *from, int length, int transhdrlen,
1540 struct ipcm_cookie *ipc, struct rtable **rtp,
1541 struct inet_cork *cork, unsigned int flags)
1542{
1543 struct sk_buff_head queue;
1544 int err;
1545
1546 if (flags & MSG_PROBE)
1547 return NULL;
1548
1549 __skb_queue_head_init(&queue);
1550
1551 cork->flags = 0;
1552 cork->addr = 0;
1553 cork->opt = NULL;
1554 err = ip_setup_cork(sk, cork, ipc, rtp);
1555 if (err)
1556 return ERR_PTR(err);
1557
1558 err = __ip_append_data(sk, fl4, &queue, cork,
1559 ¤t->task_frag, getfrag,
1560 from, length, transhdrlen, flags);
1561 if (err) {
1562 __ip_flush_pending_frames(sk, &queue, cork);
1563 return ERR_PTR(err);
1564 }
1565
1566 return __ip_make_skb(sk, fl4, &queue, cork);
1567}
1568
1569/*
1570 * Fetch data from kernel space and fill in checksum if needed.
1571 */
1572static int ip_reply_glue_bits(void *dptr, char *to, int offset,
1573 int len, int odd, struct sk_buff *skb)
1574{
1575 __wsum csum;
1576
1577 csum = csum_partial_copy_nocheck(dptr+offset, to, len);
1578 skb->csum = csum_block_add(skb->csum, csum, odd);
1579 return 0;
1580}
1581
1582/*
1583 * Generic function to send a packet as reply to another packet.
1584 * Used to send some TCP resets/acks so far.
1585 */
1586void ip_send_unicast_reply(struct sock *sk, struct sk_buff *skb,
1587 const struct ip_options *sopt,
1588 __be32 daddr, __be32 saddr,
1589 const struct ip_reply_arg *arg,
1590 unsigned int len, u64 transmit_time, u32 txhash)
1591{
1592 struct ip_options_data replyopts;
1593 struct ipcm_cookie ipc;
1594 struct flowi4 fl4;
1595 struct rtable *rt = skb_rtable(skb);
1596 struct net *net = sock_net(sk);
1597 struct sk_buff *nskb;
1598 int err;
1599 int oif;
1600
1601 if (__ip_options_echo(net, &replyopts.opt.opt, skb, sopt))
1602 return;
1603
1604 ipcm_init(&ipc);
1605 ipc.addr = daddr;
1606 ipc.sockc.transmit_time = transmit_time;
1607
1608 if (replyopts.opt.opt.optlen) {
1609 ipc.opt = &replyopts.opt;
1610
1611 if (replyopts.opt.opt.srr)
1612 daddr = replyopts.opt.opt.faddr;
1613 }
1614
1615 oif = arg->bound_dev_if;
1616 if (!oif && netif_index_is_l3_master(net, skb->skb_iif))
1617 oif = skb->skb_iif;
1618
1619 flowi4_init_output(&fl4, oif,
1620 IP4_REPLY_MARK(net, skb->mark) ?: sk->sk_mark,
1621 RT_TOS(arg->tos),
1622 RT_SCOPE_UNIVERSE, ip_hdr(skb)->protocol,
1623 ip_reply_arg_flowi_flags(arg),
1624 daddr, saddr,
1625 tcp_hdr(skb)->source, tcp_hdr(skb)->dest,
1626 arg->uid);
1627 security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4));
1628 rt = ip_route_output_flow(net, &fl4, sk);
1629 if (IS_ERR(rt))
1630 return;
1631
1632 inet_sk(sk)->tos = arg->tos & ~INET_ECN_MASK;
1633
1634 sk->sk_protocol = ip_hdr(skb)->protocol;
1635 sk->sk_bound_dev_if = arg->bound_dev_if;
1636 sk->sk_sndbuf = READ_ONCE(sysctl_wmem_default);
1637 ipc.sockc.mark = fl4.flowi4_mark;
1638 err = ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base,
1639 len, 0, &ipc, &rt, MSG_DONTWAIT);
1640 if (unlikely(err)) {
1641 ip_flush_pending_frames(sk);
1642 goto out;
1643 }
1644
1645 nskb = skb_peek(&sk->sk_write_queue);
1646 if (nskb) {
1647 if (arg->csumoffset >= 0)
1648 *((__sum16 *)skb_transport_header(nskb) +
1649 arg->csumoffset) = csum_fold(csum_add(nskb->csum,
1650 arg->csum));
1651 nskb->ip_summed = CHECKSUM_NONE;
1652 nskb->mono_delivery_time = !!transmit_time;
1653 if (txhash)
1654 skb_set_hash(nskb, txhash, PKT_HASH_TYPE_L4);
1655 ip_push_pending_frames(sk, &fl4);
1656 }
1657out:
1658 ip_rt_put(rt);
1659}
1660
1661void __init ip_init(void)
1662{
1663 ip_rt_init();
1664 inet_initpeers();
1665
1666#if defined(CONFIG_IP_MULTICAST)
1667 igmp_mc_init();
1668#endif
1669}
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 <asm/system.h>
47#include <linux/module.h>
48#include <linux/types.h>
49#include <linux/kernel.h>
50#include <linux/mm.h>
51#include <linux/string.h>
52#include <linux/errno.h>
53#include <linux/highmem.h>
54#include <linux/slab.h>
55
56#include <linux/socket.h>
57#include <linux/sockios.h>
58#include <linux/in.h>
59#include <linux/inet.h>
60#include <linux/netdevice.h>
61#include <linux/etherdevice.h>
62#include <linux/proc_fs.h>
63#include <linux/stat.h>
64#include <linux/init.h>
65
66#include <net/snmp.h>
67#include <net/ip.h>
68#include <net/protocol.h>
69#include <net/route.h>
70#include <net/xfrm.h>
71#include <linux/skbuff.h>
72#include <net/sock.h>
73#include <net/arp.h>
74#include <net/icmp.h>
75#include <net/checksum.h>
76#include <net/inetpeer.h>
77#include <linux/igmp.h>
78#include <linux/netfilter_ipv4.h>
79#include <linux/netfilter_bridge.h>
80#include <linux/mroute.h>
81#include <linux/netlink.h>
82#include <linux/tcp.h>
83
84int sysctl_ip_default_ttl __read_mostly = IPDEFTTL;
85EXPORT_SYMBOL(sysctl_ip_default_ttl);
86
87/* Generate a checksum for an outgoing IP datagram. */
88__inline__ void 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 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, skb, NULL,
102 skb_dst(skb)->dev, dst_output);
103}
104
105int ip_local_out(struct sk_buff *skb)
106{
107 int err;
108
109 err = __ip_local_out(skb);
110 if (likely(err == 1))
111 err = dst_output(skb);
112
113 return err;
114}
115EXPORT_SYMBOL_GPL(ip_local_out);
116
117/* dev_loopback_xmit for use with netfilter. */
118static int ip_dev_loopback_xmit(struct sk_buff *newskb)
119{
120 skb_reset_mac_header(newskb);
121 __skb_pull(newskb, skb_network_offset(newskb));
122 newskb->pkt_type = PACKET_LOOPBACK;
123 newskb->ip_summed = CHECKSUM_UNNECESSARY;
124 WARN_ON(!skb_dst(newskb));
125 skb_dst_force(newskb);
126 netif_rx_ni(newskb);
127 return 0;
128}
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, 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 iphdr *iph;
149
150 /* Build the IP header. */
151 skb_push(skb, sizeof(struct iphdr) + (opt ? opt->opt.optlen : 0));
152 skb_reset_network_header(skb);
153 iph = ip_hdr(skb);
154 iph->version = 4;
155 iph->ihl = 5;
156 iph->tos = inet->tos;
157 if (ip_dont_fragment(sk, &rt->dst))
158 iph->frag_off = htons(IP_DF);
159 else
160 iph->frag_off = 0;
161 iph->ttl = ip_select_ttl(inet, &rt->dst);
162 iph->daddr = (opt && opt->opt.srr ? opt->opt.faddr : daddr);
163 iph->saddr = saddr;
164 iph->protocol = sk->sk_protocol;
165 ip_select_ident(iph, &rt->dst, sk);
166
167 if (opt && opt->opt.optlen) {
168 iph->ihl += opt->opt.optlen>>2;
169 ip_options_build(skb, &opt->opt, daddr, rt, 0);
170 }
171
172 skb->priority = sk->sk_priority;
173 skb->mark = sk->sk_mark;
174
175 /* Send it out. */
176 return ip_local_out(skb);
177}
178EXPORT_SYMBOL_GPL(ip_build_and_send_pkt);
179
180static inline int ip_finish_output2(struct sk_buff *skb)
181{
182 struct dst_entry *dst = skb_dst(skb);
183 struct rtable *rt = (struct rtable *)dst;
184 struct net_device *dev = dst->dev;
185 unsigned int hh_len = LL_RESERVED_SPACE(dev);
186 struct neighbour *neigh;
187
188 if (rt->rt_type == RTN_MULTICAST) {
189 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUTMCAST, skb->len);
190 } else if (rt->rt_type == RTN_BROADCAST)
191 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUTBCAST, skb->len);
192
193 /* Be paranoid, rather than too clever. */
194 if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) {
195 struct sk_buff *skb2;
196
197 skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev));
198 if (skb2 == NULL) {
199 kfree_skb(skb);
200 return -ENOMEM;
201 }
202 if (skb->sk)
203 skb_set_owner_w(skb2, skb->sk);
204 kfree_skb(skb);
205 skb = skb2;
206 }
207
208 rcu_read_lock();
209 neigh = dst_get_neighbour(dst);
210 if (neigh) {
211 int res = neigh_output(neigh, skb);
212
213 rcu_read_unlock();
214 return res;
215 }
216 rcu_read_unlock();
217
218 if (net_ratelimit())
219 printk(KERN_DEBUG "ip_finish_output2: No header cache and no neighbour!\n");
220 kfree_skb(skb);
221 return -EINVAL;
222}
223
224static inline int ip_skb_dst_mtu(struct sk_buff *skb)
225{
226 struct inet_sock *inet = skb->sk ? inet_sk(skb->sk) : NULL;
227
228 return (inet && inet->pmtudisc == IP_PMTUDISC_PROBE) ?
229 skb_dst(skb)->dev->mtu : dst_mtu(skb_dst(skb));
230}
231
232static int ip_finish_output(struct sk_buff *skb)
233{
234#if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
235 /* Policy lookup after SNAT yielded a new policy */
236 if (skb_dst(skb)->xfrm != NULL) {
237 IPCB(skb)->flags |= IPSKB_REROUTED;
238 return dst_output(skb);
239 }
240#endif
241 if (skb->len > ip_skb_dst_mtu(skb) && !skb_is_gso(skb))
242 return ip_fragment(skb, ip_finish_output2);
243 else
244 return ip_finish_output2(skb);
245}
246
247int ip_mc_output(struct sk_buff *skb)
248{
249 struct sock *sk = skb->sk;
250 struct rtable *rt = skb_rtable(skb);
251 struct net_device *dev = rt->dst.dev;
252
253 /*
254 * If the indicated interface is up and running, send the packet.
255 */
256 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len);
257
258 skb->dev = dev;
259 skb->protocol = htons(ETH_P_IP);
260
261 /*
262 * Multicasts are looped back for other local users
263 */
264
265 if (rt->rt_flags&RTCF_MULTICAST) {
266 if (sk_mc_loop(sk)
267#ifdef CONFIG_IP_MROUTE
268 /* Small optimization: do not loopback not local frames,
269 which returned after forwarding; they will be dropped
270 by ip_mr_input in any case.
271 Note, that local frames are looped back to be delivered
272 to local recipients.
273
274 This check is duplicated in ip_mr_input at the moment.
275 */
276 &&
277 ((rt->rt_flags & RTCF_LOCAL) ||
278 !(IPCB(skb)->flags & IPSKB_FORWARDED))
279#endif
280 ) {
281 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
282 if (newskb)
283 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
284 newskb, NULL, newskb->dev,
285 ip_dev_loopback_xmit);
286 }
287
288 /* Multicasts with ttl 0 must not go beyond the host */
289
290 if (ip_hdr(skb)->ttl == 0) {
291 kfree_skb(skb);
292 return 0;
293 }
294 }
295
296 if (rt->rt_flags&RTCF_BROADCAST) {
297 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
298 if (newskb)
299 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, newskb,
300 NULL, newskb->dev, ip_dev_loopback_xmit);
301 }
302
303 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb, NULL,
304 skb->dev, ip_finish_output,
305 !(IPCB(skb)->flags & IPSKB_REROUTED));
306}
307
308int ip_output(struct sk_buff *skb)
309{
310 struct net_device *dev = skb_dst(skb)->dev;
311
312 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len);
313
314 skb->dev = dev;
315 skb->protocol = htons(ETH_P_IP);
316
317 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb, NULL, dev,
318 ip_finish_output,
319 !(IPCB(skb)->flags & IPSKB_REROUTED));
320}
321
322int ip_queue_xmit(struct sk_buff *skb, struct flowi *fl)
323{
324 struct sock *sk = skb->sk;
325 struct inet_sock *inet = inet_sk(sk);
326 struct ip_options_rcu *inet_opt;
327 struct flowi4 *fl4;
328 struct rtable *rt;
329 struct iphdr *iph;
330 int res;
331
332 /* Skip all of this if the packet is already routed,
333 * f.e. by something like SCTP.
334 */
335 rcu_read_lock();
336 inet_opt = rcu_dereference(inet->inet_opt);
337 fl4 = &fl->u.ip4;
338 rt = skb_rtable(skb);
339 if (rt != NULL)
340 goto packet_routed;
341
342 /* Make sure we can route this packet. */
343 rt = (struct rtable *)__sk_dst_check(sk, 0);
344 if (rt == NULL) {
345 __be32 daddr;
346
347 /* Use correct destination address if we have options. */
348 daddr = inet->inet_daddr;
349 if (inet_opt && inet_opt->opt.srr)
350 daddr = inet_opt->opt.faddr;
351
352 /* If this fails, retransmit mechanism of transport layer will
353 * keep trying until route appears or the connection times
354 * itself out.
355 */
356 rt = ip_route_output_ports(sock_net(sk), fl4, sk,
357 daddr, inet->inet_saddr,
358 inet->inet_dport,
359 inet->inet_sport,
360 sk->sk_protocol,
361 RT_CONN_FLAGS(sk),
362 sk->sk_bound_dev_if);
363 if (IS_ERR(rt))
364 goto no_route;
365 sk_setup_caps(sk, &rt->dst);
366 }
367 skb_dst_set_noref(skb, &rt->dst);
368
369packet_routed:
370 if (inet_opt && inet_opt->opt.is_strictroute && fl4->daddr != rt->rt_gateway)
371 goto no_route;
372
373 /* OK, we know where to send it, allocate and build IP header. */
374 skb_push(skb, sizeof(struct iphdr) + (inet_opt ? inet_opt->opt.optlen : 0));
375 skb_reset_network_header(skb);
376 iph = ip_hdr(skb);
377 *((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (inet->tos & 0xff));
378 if (ip_dont_fragment(sk, &rt->dst) && !skb->local_df)
379 iph->frag_off = htons(IP_DF);
380 else
381 iph->frag_off = 0;
382 iph->ttl = ip_select_ttl(inet, &rt->dst);
383 iph->protocol = sk->sk_protocol;
384 iph->saddr = fl4->saddr;
385 iph->daddr = fl4->daddr;
386 /* Transport layer set skb->h.foo itself. */
387
388 if (inet_opt && inet_opt->opt.optlen) {
389 iph->ihl += inet_opt->opt.optlen >> 2;
390 ip_options_build(skb, &inet_opt->opt, inet->inet_daddr, rt, 0);
391 }
392
393 ip_select_ident_more(iph, &rt->dst, sk,
394 (skb_shinfo(skb)->gso_segs ?: 1) - 1);
395
396 skb->priority = sk->sk_priority;
397 skb->mark = sk->sk_mark;
398
399 res = ip_local_out(skb);
400 rcu_read_unlock();
401 return res;
402
403no_route:
404 rcu_read_unlock();
405 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
406 kfree_skb(skb);
407 return -EHOSTUNREACH;
408}
409EXPORT_SYMBOL(ip_queue_xmit);
410
411
412static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from)
413{
414 to->pkt_type = from->pkt_type;
415 to->priority = from->priority;
416 to->protocol = from->protocol;
417 skb_dst_drop(to);
418 skb_dst_copy(to, from);
419 to->dev = from->dev;
420 to->mark = from->mark;
421
422 /* Copy the flags to each fragment. */
423 IPCB(to)->flags = IPCB(from)->flags;
424
425#ifdef CONFIG_NET_SCHED
426 to->tc_index = from->tc_index;
427#endif
428 nf_copy(to, from);
429#if defined(CONFIG_NETFILTER_XT_TARGET_TRACE) || \
430 defined(CONFIG_NETFILTER_XT_TARGET_TRACE_MODULE)
431 to->nf_trace = from->nf_trace;
432#endif
433#if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
434 to->ipvs_property = from->ipvs_property;
435#endif
436 skb_copy_secmark(to, from);
437}
438
439/*
440 * This IP datagram is too large to be sent in one piece. Break it up into
441 * smaller pieces (each of size equal to IP header plus
442 * a block of the data of the original IP data part) that will yet fit in a
443 * single device frame, and queue such a frame for sending.
444 */
445
446int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *))
447{
448 struct iphdr *iph;
449 int ptr;
450 struct net_device *dev;
451 struct sk_buff *skb2;
452 unsigned int mtu, hlen, left, len, ll_rs;
453 int offset;
454 __be16 not_last_frag;
455 struct rtable *rt = skb_rtable(skb);
456 int err = 0;
457
458 dev = rt->dst.dev;
459
460 /*
461 * Point into the IP datagram header.
462 */
463
464 iph = ip_hdr(skb);
465
466 if (unlikely((iph->frag_off & htons(IP_DF)) && !skb->local_df)) {
467 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
468 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
469 htonl(ip_skb_dst_mtu(skb)));
470 kfree_skb(skb);
471 return -EMSGSIZE;
472 }
473
474 /*
475 * Setup starting values.
476 */
477
478 hlen = iph->ihl * 4;
479 mtu = dst_mtu(&rt->dst) - hlen; /* Size of data space */
480#ifdef CONFIG_BRIDGE_NETFILTER
481 if (skb->nf_bridge)
482 mtu -= nf_bridge_mtu_reduction(skb);
483#endif
484 IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE;
485
486 /* When frag_list is given, use it. First, check its validity:
487 * some transformers could create wrong frag_list or break existing
488 * one, it is not prohibited. In this case fall back to copying.
489 *
490 * LATER: this step can be merged to real generation of fragments,
491 * we can switch to copy when see the first bad fragment.
492 */
493 if (skb_has_frag_list(skb)) {
494 struct sk_buff *frag, *frag2;
495 int first_len = skb_pagelen(skb);
496
497 if (first_len - hlen > mtu ||
498 ((first_len - hlen) & 7) ||
499 ip_is_fragment(iph) ||
500 skb_cloned(skb))
501 goto slow_path;
502
503 skb_walk_frags(skb, frag) {
504 /* Correct geometry. */
505 if (frag->len > mtu ||
506 ((frag->len & 7) && frag->next) ||
507 skb_headroom(frag) < hlen)
508 goto slow_path_clean;
509
510 /* Partially cloned skb? */
511 if (skb_shared(frag))
512 goto slow_path_clean;
513
514 BUG_ON(frag->sk);
515 if (skb->sk) {
516 frag->sk = skb->sk;
517 frag->destructor = sock_wfree;
518 }
519 skb->truesize -= frag->truesize;
520 }
521
522 /* Everything is OK. Generate! */
523
524 err = 0;
525 offset = 0;
526 frag = skb_shinfo(skb)->frag_list;
527 skb_frag_list_init(skb);
528 skb->data_len = first_len - skb_headlen(skb);
529 skb->len = first_len;
530 iph->tot_len = htons(first_len);
531 iph->frag_off = htons(IP_MF);
532 ip_send_check(iph);
533
534 for (;;) {
535 /* Prepare header of the next frame,
536 * before previous one went down. */
537 if (frag) {
538 frag->ip_summed = CHECKSUM_NONE;
539 skb_reset_transport_header(frag);
540 __skb_push(frag, hlen);
541 skb_reset_network_header(frag);
542 memcpy(skb_network_header(frag), iph, hlen);
543 iph = ip_hdr(frag);
544 iph->tot_len = htons(frag->len);
545 ip_copy_metadata(frag, skb);
546 if (offset == 0)
547 ip_options_fragment(frag);
548 offset += skb->len - hlen;
549 iph->frag_off = htons(offset>>3);
550 if (frag->next != NULL)
551 iph->frag_off |= htons(IP_MF);
552 /* Ready, complete checksum */
553 ip_send_check(iph);
554 }
555
556 err = output(skb);
557
558 if (!err)
559 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES);
560 if (err || !frag)
561 break;
562
563 skb = frag;
564 frag = skb->next;
565 skb->next = NULL;
566 }
567
568 if (err == 0) {
569 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS);
570 return 0;
571 }
572
573 while (frag) {
574 skb = frag->next;
575 kfree_skb(frag);
576 frag = skb;
577 }
578 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
579 return err;
580
581slow_path_clean:
582 skb_walk_frags(skb, frag2) {
583 if (frag2 == frag)
584 break;
585 frag2->sk = NULL;
586 frag2->destructor = NULL;
587 skb->truesize += frag2->truesize;
588 }
589 }
590
591slow_path:
592 left = skb->len - hlen; /* Space per frame */
593 ptr = hlen; /* Where to start from */
594
595 /* for bridged IP traffic encapsulated inside f.e. a vlan header,
596 * we need to make room for the encapsulating header
597 */
598 ll_rs = LL_RESERVED_SPACE_EXTRA(rt->dst.dev, nf_bridge_pad(skb));
599
600 /*
601 * Fragment the datagram.
602 */
603
604 offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3;
605 not_last_frag = iph->frag_off & htons(IP_MF);
606
607 /*
608 * Keep copying data until we run out.
609 */
610
611 while (left > 0) {
612 len = left;
613 /* IF: it doesn't fit, use 'mtu' - the data space left */
614 if (len > mtu)
615 len = mtu;
616 /* IF: we are not sending up to and including the packet end
617 then align the next start on an eight byte boundary */
618 if (len < left) {
619 len &= ~7;
620 }
621 /*
622 * Allocate buffer.
623 */
624
625 if ((skb2 = alloc_skb(len+hlen+ll_rs, GFP_ATOMIC)) == NULL) {
626 NETDEBUG(KERN_INFO "IP: frag: no memory for new fragment!\n");
627 err = -ENOMEM;
628 goto fail;
629 }
630
631 /*
632 * Set up data on packet
633 */
634
635 ip_copy_metadata(skb2, skb);
636 skb_reserve(skb2, ll_rs);
637 skb_put(skb2, len + hlen);
638 skb_reset_network_header(skb2);
639 skb2->transport_header = skb2->network_header + hlen;
640
641 /*
642 * Charge the memory for the fragment to any owner
643 * it might possess
644 */
645
646 if (skb->sk)
647 skb_set_owner_w(skb2, skb->sk);
648
649 /*
650 * Copy the packet header into the new buffer.
651 */
652
653 skb_copy_from_linear_data(skb, skb_network_header(skb2), hlen);
654
655 /*
656 * Copy a block of the IP datagram.
657 */
658 if (skb_copy_bits(skb, ptr, skb_transport_header(skb2), len))
659 BUG();
660 left -= len;
661
662 /*
663 * Fill in the new header fields.
664 */
665 iph = ip_hdr(skb2);
666 iph->frag_off = htons((offset >> 3));
667
668 /* ANK: dirty, but effective trick. Upgrade options only if
669 * the segment to be fragmented was THE FIRST (otherwise,
670 * options are already fixed) and make it ONCE
671 * on the initial skb, so that all the following fragments
672 * will inherit fixed options.
673 */
674 if (offset == 0)
675 ip_options_fragment(skb);
676
677 /*
678 * Added AC : If we are fragmenting a fragment that's not the
679 * last fragment then keep MF on each bit
680 */
681 if (left > 0 || not_last_frag)
682 iph->frag_off |= htons(IP_MF);
683 ptr += len;
684 offset += len;
685
686 /*
687 * Put this fragment into the sending queue.
688 */
689 iph->tot_len = htons(len + hlen);
690
691 ip_send_check(iph);
692
693 err = output(skb2);
694 if (err)
695 goto fail;
696
697 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES);
698 }
699 kfree_skb(skb);
700 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS);
701 return err;
702
703fail:
704 kfree_skb(skb);
705 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
706 return err;
707}
708EXPORT_SYMBOL(ip_fragment);
709
710int
711ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
712{
713 struct iovec *iov = from;
714
715 if (skb->ip_summed == CHECKSUM_PARTIAL) {
716 if (memcpy_fromiovecend(to, iov, offset, len) < 0)
717 return -EFAULT;
718 } else {
719 __wsum csum = 0;
720 if (csum_partial_copy_fromiovecend(to, iov, offset, len, &csum) < 0)
721 return -EFAULT;
722 skb->csum = csum_block_add(skb->csum, csum, odd);
723 }
724 return 0;
725}
726EXPORT_SYMBOL(ip_generic_getfrag);
727
728static inline __wsum
729csum_page(struct page *page, int offset, int copy)
730{
731 char *kaddr;
732 __wsum csum;
733 kaddr = kmap(page);
734 csum = csum_partial(kaddr + offset, copy, 0);
735 kunmap(page);
736 return csum;
737}
738
739static inline int ip_ufo_append_data(struct sock *sk,
740 struct sk_buff_head *queue,
741 int getfrag(void *from, char *to, int offset, int len,
742 int odd, struct sk_buff *skb),
743 void *from, int length, int hh_len, int fragheaderlen,
744 int transhdrlen, int maxfraglen, unsigned int flags)
745{
746 struct sk_buff *skb;
747 int err;
748
749 /* There is support for UDP fragmentation offload by network
750 * device, so create one single skb packet containing complete
751 * udp datagram
752 */
753 if ((skb = skb_peek_tail(queue)) == NULL) {
754 skb = sock_alloc_send_skb(sk,
755 hh_len + fragheaderlen + transhdrlen + 20,
756 (flags & MSG_DONTWAIT), &err);
757
758 if (skb == NULL)
759 return err;
760
761 /* reserve space for Hardware header */
762 skb_reserve(skb, hh_len);
763
764 /* create space for UDP/IP header */
765 skb_put(skb, fragheaderlen + transhdrlen);
766
767 /* initialize network header pointer */
768 skb_reset_network_header(skb);
769
770 /* initialize protocol header pointer */
771 skb->transport_header = skb->network_header + fragheaderlen;
772
773 skb->ip_summed = CHECKSUM_PARTIAL;
774 skb->csum = 0;
775
776 /* specify the length of each IP datagram fragment */
777 skb_shinfo(skb)->gso_size = maxfraglen - fragheaderlen;
778 skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
779 __skb_queue_tail(queue, skb);
780 }
781
782 return skb_append_datato_frags(sk, skb, getfrag, from,
783 (length - transhdrlen));
784}
785
786static int __ip_append_data(struct sock *sk,
787 struct flowi4 *fl4,
788 struct sk_buff_head *queue,
789 struct inet_cork *cork,
790 int getfrag(void *from, char *to, int offset,
791 int len, int odd, struct sk_buff *skb),
792 void *from, int length, int transhdrlen,
793 unsigned int flags)
794{
795 struct inet_sock *inet = inet_sk(sk);
796 struct sk_buff *skb;
797
798 struct ip_options *opt = cork->opt;
799 int hh_len;
800 int exthdrlen;
801 int mtu;
802 int copy;
803 int err;
804 int offset = 0;
805 unsigned int maxfraglen, fragheaderlen;
806 int csummode = CHECKSUM_NONE;
807 struct rtable *rt = (struct rtable *)cork->dst;
808
809 skb = skb_peek_tail(queue);
810
811 exthdrlen = !skb ? rt->dst.header_len : 0;
812 mtu = cork->fragsize;
813
814 hh_len = LL_RESERVED_SPACE(rt->dst.dev);
815
816 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
817 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
818
819 if (cork->length + length > 0xFFFF - fragheaderlen) {
820 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
821 mtu-exthdrlen);
822 return -EMSGSIZE;
823 }
824
825 /*
826 * transhdrlen > 0 means that this is the first fragment and we wish
827 * it won't be fragmented in the future.
828 */
829 if (transhdrlen &&
830 length + fragheaderlen <= mtu &&
831 rt->dst.dev->features & NETIF_F_V4_CSUM &&
832 !exthdrlen)
833 csummode = CHECKSUM_PARTIAL;
834
835 cork->length += length;
836 if (((length > mtu) || (skb && skb_is_gso(skb))) &&
837 (sk->sk_protocol == IPPROTO_UDP) &&
838 (rt->dst.dev->features & NETIF_F_UFO) && !rt->dst.header_len) {
839 err = ip_ufo_append_data(sk, queue, getfrag, from, length,
840 hh_len, fragheaderlen, transhdrlen,
841 maxfraglen, flags);
842 if (err)
843 goto error;
844 return 0;
845 }
846
847 /* So, what's going on in the loop below?
848 *
849 * We use calculated fragment length to generate chained skb,
850 * each of segments is IP fragment ready for sending to network after
851 * adding appropriate IP header.
852 */
853
854 if (!skb)
855 goto alloc_new_skb;
856
857 while (length > 0) {
858 /* Check if the remaining data fits into current packet. */
859 copy = mtu - skb->len;
860 if (copy < length)
861 copy = maxfraglen - skb->len;
862 if (copy <= 0) {
863 char *data;
864 unsigned int datalen;
865 unsigned int fraglen;
866 unsigned int fraggap;
867 unsigned int alloclen;
868 struct sk_buff *skb_prev;
869alloc_new_skb:
870 skb_prev = skb;
871 if (skb_prev)
872 fraggap = skb_prev->len - maxfraglen;
873 else
874 fraggap = 0;
875
876 /*
877 * If remaining data exceeds the mtu,
878 * we know we need more fragment(s).
879 */
880 datalen = length + fraggap;
881 if (datalen > mtu - fragheaderlen)
882 datalen = maxfraglen - fragheaderlen;
883 fraglen = datalen + fragheaderlen;
884
885 if ((flags & MSG_MORE) &&
886 !(rt->dst.dev->features&NETIF_F_SG))
887 alloclen = mtu;
888 else
889 alloclen = fraglen;
890
891 alloclen += exthdrlen;
892
893 /* The last fragment gets additional space at tail.
894 * Note, with MSG_MORE we overallocate on fragments,
895 * because we have no idea what fragment will be
896 * the last.
897 */
898 if (datalen == length + fraggap)
899 alloclen += rt->dst.trailer_len;
900
901 if (transhdrlen) {
902 skb = sock_alloc_send_skb(sk,
903 alloclen + hh_len + 15,
904 (flags & MSG_DONTWAIT), &err);
905 } else {
906 skb = NULL;
907 if (atomic_read(&sk->sk_wmem_alloc) <=
908 2 * sk->sk_sndbuf)
909 skb = sock_wmalloc(sk,
910 alloclen + hh_len + 15, 1,
911 sk->sk_allocation);
912 if (unlikely(skb == NULL))
913 err = -ENOBUFS;
914 else
915 /* only the initial fragment is
916 time stamped */
917 cork->tx_flags = 0;
918 }
919 if (skb == NULL)
920 goto error;
921
922 /*
923 * Fill in the control structures
924 */
925 skb->ip_summed = csummode;
926 skb->csum = 0;
927 skb_reserve(skb, hh_len);
928 skb_shinfo(skb)->tx_flags = cork->tx_flags;
929
930 /*
931 * Find where to start putting bytes.
932 */
933 data = skb_put(skb, fraglen + exthdrlen);
934 skb_set_network_header(skb, exthdrlen);
935 skb->transport_header = (skb->network_header +
936 fragheaderlen);
937 data += fragheaderlen + exthdrlen;
938
939 if (fraggap) {
940 skb->csum = skb_copy_and_csum_bits(
941 skb_prev, maxfraglen,
942 data + transhdrlen, fraggap, 0);
943 skb_prev->csum = csum_sub(skb_prev->csum,
944 skb->csum);
945 data += fraggap;
946 pskb_trim_unique(skb_prev, maxfraglen);
947 }
948
949 copy = datalen - transhdrlen - fraggap;
950 if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) {
951 err = -EFAULT;
952 kfree_skb(skb);
953 goto error;
954 }
955
956 offset += copy;
957 length -= datalen - fraggap;
958 transhdrlen = 0;
959 exthdrlen = 0;
960 csummode = CHECKSUM_NONE;
961
962 /*
963 * Put the packet on the pending queue.
964 */
965 __skb_queue_tail(queue, skb);
966 continue;
967 }
968
969 if (copy > length)
970 copy = length;
971
972 if (!(rt->dst.dev->features&NETIF_F_SG)) {
973 unsigned int off;
974
975 off = skb->len;
976 if (getfrag(from, skb_put(skb, copy),
977 offset, copy, off, skb) < 0) {
978 __skb_trim(skb, off);
979 err = -EFAULT;
980 goto error;
981 }
982 } else {
983 int i = skb_shinfo(skb)->nr_frags;
984 skb_frag_t *frag = &skb_shinfo(skb)->frags[i-1];
985 struct page *page = cork->page;
986 int off = cork->off;
987 unsigned int left;
988
989 if (page && (left = PAGE_SIZE - off) > 0) {
990 if (copy >= left)
991 copy = left;
992 if (page != frag->page) {
993 if (i == MAX_SKB_FRAGS) {
994 err = -EMSGSIZE;
995 goto error;
996 }
997 get_page(page);
998 skb_fill_page_desc(skb, i, page, off, 0);
999 frag = &skb_shinfo(skb)->frags[i];
1000 }
1001 } else if (i < MAX_SKB_FRAGS) {
1002 if (copy > PAGE_SIZE)
1003 copy = PAGE_SIZE;
1004 page = alloc_pages(sk->sk_allocation, 0);
1005 if (page == NULL) {
1006 err = -ENOMEM;
1007 goto error;
1008 }
1009 cork->page = page;
1010 cork->off = 0;
1011
1012 skb_fill_page_desc(skb, i, page, 0, 0);
1013 frag = &skb_shinfo(skb)->frags[i];
1014 } else {
1015 err = -EMSGSIZE;
1016 goto error;
1017 }
1018 if (getfrag(from, page_address(frag->page)+frag->page_offset+frag->size, offset, copy, skb->len, skb) < 0) {
1019 err = -EFAULT;
1020 goto error;
1021 }
1022 cork->off += copy;
1023 frag->size += copy;
1024 skb->len += copy;
1025 skb->data_len += copy;
1026 skb->truesize += copy;
1027 atomic_add(copy, &sk->sk_wmem_alloc);
1028 }
1029 offset += copy;
1030 length -= copy;
1031 }
1032
1033 return 0;
1034
1035error:
1036 cork->length -= length;
1037 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1038 return err;
1039}
1040
1041static int ip_setup_cork(struct sock *sk, struct inet_cork *cork,
1042 struct ipcm_cookie *ipc, struct rtable **rtp)
1043{
1044 struct inet_sock *inet = inet_sk(sk);
1045 struct ip_options_rcu *opt;
1046 struct rtable *rt;
1047
1048 /*
1049 * setup for corking.
1050 */
1051 opt = ipc->opt;
1052 if (opt) {
1053 if (cork->opt == NULL) {
1054 cork->opt = kmalloc(sizeof(struct ip_options) + 40,
1055 sk->sk_allocation);
1056 if (unlikely(cork->opt == NULL))
1057 return -ENOBUFS;
1058 }
1059 memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen);
1060 cork->flags |= IPCORK_OPT;
1061 cork->addr = ipc->addr;
1062 }
1063 rt = *rtp;
1064 if (unlikely(!rt))
1065 return -EFAULT;
1066 /*
1067 * We steal reference to this route, caller should not release it
1068 */
1069 *rtp = NULL;
1070 cork->fragsize = inet->pmtudisc == IP_PMTUDISC_PROBE ?
1071 rt->dst.dev->mtu : dst_mtu(&rt->dst);
1072 cork->dst = &rt->dst;
1073 cork->length = 0;
1074 cork->tx_flags = ipc->tx_flags;
1075 cork->page = NULL;
1076 cork->off = 0;
1077
1078 return 0;
1079}
1080
1081/*
1082 * ip_append_data() and ip_append_page() can make one large IP datagram
1083 * from many pieces of data. Each pieces will be holded on the socket
1084 * until ip_push_pending_frames() is called. Each piece can be a page
1085 * or non-page data.
1086 *
1087 * Not only UDP, other transport protocols - e.g. raw sockets - can use
1088 * this interface potentially.
1089 *
1090 * LATER: length must be adjusted by pad at tail, when it is required.
1091 */
1092int ip_append_data(struct sock *sk, struct flowi4 *fl4,
1093 int getfrag(void *from, char *to, int offset, int len,
1094 int odd, struct sk_buff *skb),
1095 void *from, int length, int transhdrlen,
1096 struct ipcm_cookie *ipc, struct rtable **rtp,
1097 unsigned int flags)
1098{
1099 struct inet_sock *inet = inet_sk(sk);
1100 int err;
1101
1102 if (flags&MSG_PROBE)
1103 return 0;
1104
1105 if (skb_queue_empty(&sk->sk_write_queue)) {
1106 err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp);
1107 if (err)
1108 return err;
1109 } else {
1110 transhdrlen = 0;
1111 }
1112
1113 return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base, getfrag,
1114 from, length, transhdrlen, flags);
1115}
1116
1117ssize_t ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page,
1118 int offset, size_t size, int flags)
1119{
1120 struct inet_sock *inet = inet_sk(sk);
1121 struct sk_buff *skb;
1122 struct rtable *rt;
1123 struct ip_options *opt = NULL;
1124 struct inet_cork *cork;
1125 int hh_len;
1126 int mtu;
1127 int len;
1128 int err;
1129 unsigned int maxfraglen, fragheaderlen, fraggap;
1130
1131 if (inet->hdrincl)
1132 return -EPERM;
1133
1134 if (flags&MSG_PROBE)
1135 return 0;
1136
1137 if (skb_queue_empty(&sk->sk_write_queue))
1138 return -EINVAL;
1139
1140 cork = &inet->cork.base;
1141 rt = (struct rtable *)cork->dst;
1142 if (cork->flags & IPCORK_OPT)
1143 opt = cork->opt;
1144
1145 if (!(rt->dst.dev->features&NETIF_F_SG))
1146 return -EOPNOTSUPP;
1147
1148 hh_len = LL_RESERVED_SPACE(rt->dst.dev);
1149 mtu = cork->fragsize;
1150
1151 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
1152 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
1153
1154 if (cork->length + size > 0xFFFF - fragheaderlen) {
1155 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport, mtu);
1156 return -EMSGSIZE;
1157 }
1158
1159 if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL)
1160 return -EINVAL;
1161
1162 cork->length += size;
1163 if ((size + skb->len > mtu) &&
1164 (sk->sk_protocol == IPPROTO_UDP) &&
1165 (rt->dst.dev->features & NETIF_F_UFO)) {
1166 skb_shinfo(skb)->gso_size = mtu - fragheaderlen;
1167 skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
1168 }
1169
1170
1171 while (size > 0) {
1172 int i;
1173
1174 if (skb_is_gso(skb))
1175 len = size;
1176 else {
1177
1178 /* Check if the remaining data fits into current packet. */
1179 len = mtu - skb->len;
1180 if (len < size)
1181 len = maxfraglen - skb->len;
1182 }
1183 if (len <= 0) {
1184 struct sk_buff *skb_prev;
1185 int alloclen;
1186
1187 skb_prev = skb;
1188 fraggap = skb_prev->len - maxfraglen;
1189
1190 alloclen = fragheaderlen + hh_len + fraggap + 15;
1191 skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation);
1192 if (unlikely(!skb)) {
1193 err = -ENOBUFS;
1194 goto error;
1195 }
1196
1197 /*
1198 * Fill in the control structures
1199 */
1200 skb->ip_summed = CHECKSUM_NONE;
1201 skb->csum = 0;
1202 skb_reserve(skb, hh_len);
1203
1204 /*
1205 * Find where to start putting bytes.
1206 */
1207 skb_put(skb, fragheaderlen + fraggap);
1208 skb_reset_network_header(skb);
1209 skb->transport_header = (skb->network_header +
1210 fragheaderlen);
1211 if (fraggap) {
1212 skb->csum = skb_copy_and_csum_bits(skb_prev,
1213 maxfraglen,
1214 skb_transport_header(skb),
1215 fraggap, 0);
1216 skb_prev->csum = csum_sub(skb_prev->csum,
1217 skb->csum);
1218 pskb_trim_unique(skb_prev, maxfraglen);
1219 }
1220
1221 /*
1222 * Put the packet on the pending queue.
1223 */
1224 __skb_queue_tail(&sk->sk_write_queue, skb);
1225 continue;
1226 }
1227
1228 i = skb_shinfo(skb)->nr_frags;
1229 if (len > size)
1230 len = size;
1231 if (skb_can_coalesce(skb, i, page, offset)) {
1232 skb_shinfo(skb)->frags[i-1].size += len;
1233 } else if (i < MAX_SKB_FRAGS) {
1234 get_page(page);
1235 skb_fill_page_desc(skb, i, page, offset, len);
1236 } else {
1237 err = -EMSGSIZE;
1238 goto error;
1239 }
1240
1241 if (skb->ip_summed == CHECKSUM_NONE) {
1242 __wsum csum;
1243 csum = csum_page(page, offset, len);
1244 skb->csum = csum_block_add(skb->csum, csum, skb->len);
1245 }
1246
1247 skb->len += len;
1248 skb->data_len += len;
1249 skb->truesize += len;
1250 atomic_add(len, &sk->sk_wmem_alloc);
1251 offset += len;
1252 size -= len;
1253 }
1254 return 0;
1255
1256error:
1257 cork->length -= size;
1258 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1259 return err;
1260}
1261
1262static void ip_cork_release(struct inet_cork *cork)
1263{
1264 cork->flags &= ~IPCORK_OPT;
1265 kfree(cork->opt);
1266 cork->opt = NULL;
1267 dst_release(cork->dst);
1268 cork->dst = NULL;
1269}
1270
1271/*
1272 * Combined all pending IP fragments on the socket as one IP datagram
1273 * and push them out.
1274 */
1275struct sk_buff *__ip_make_skb(struct sock *sk,
1276 struct flowi4 *fl4,
1277 struct sk_buff_head *queue,
1278 struct inet_cork *cork)
1279{
1280 struct sk_buff *skb, *tmp_skb;
1281 struct sk_buff **tail_skb;
1282 struct inet_sock *inet = inet_sk(sk);
1283 struct net *net = sock_net(sk);
1284 struct ip_options *opt = NULL;
1285 struct rtable *rt = (struct rtable *)cork->dst;
1286 struct iphdr *iph;
1287 __be16 df = 0;
1288 __u8 ttl;
1289
1290 if ((skb = __skb_dequeue(queue)) == NULL)
1291 goto out;
1292 tail_skb = &(skb_shinfo(skb)->frag_list);
1293
1294 /* move skb->data to ip header from ext header */
1295 if (skb->data < skb_network_header(skb))
1296 __skb_pull(skb, skb_network_offset(skb));
1297 while ((tmp_skb = __skb_dequeue(queue)) != NULL) {
1298 __skb_pull(tmp_skb, skb_network_header_len(skb));
1299 *tail_skb = tmp_skb;
1300 tail_skb = &(tmp_skb->next);
1301 skb->len += tmp_skb->len;
1302 skb->data_len += tmp_skb->len;
1303 skb->truesize += tmp_skb->truesize;
1304 tmp_skb->destructor = NULL;
1305 tmp_skb->sk = NULL;
1306 }
1307
1308 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow
1309 * to fragment the frame generated here. No matter, what transforms
1310 * how transforms change size of the packet, it will come out.
1311 */
1312 if (inet->pmtudisc < IP_PMTUDISC_DO)
1313 skb->local_df = 1;
1314
1315 /* DF bit is set when we want to see DF on outgoing frames.
1316 * If local_df is set too, we still allow to fragment this frame
1317 * locally. */
1318 if (inet->pmtudisc >= IP_PMTUDISC_DO ||
1319 (skb->len <= dst_mtu(&rt->dst) &&
1320 ip_dont_fragment(sk, &rt->dst)))
1321 df = htons(IP_DF);
1322
1323 if (cork->flags & IPCORK_OPT)
1324 opt = cork->opt;
1325
1326 if (rt->rt_type == RTN_MULTICAST)
1327 ttl = inet->mc_ttl;
1328 else
1329 ttl = ip_select_ttl(inet, &rt->dst);
1330
1331 iph = (struct iphdr *)skb->data;
1332 iph->version = 4;
1333 iph->ihl = 5;
1334 iph->tos = inet->tos;
1335 iph->frag_off = df;
1336 ip_select_ident(iph, &rt->dst, sk);
1337 iph->ttl = ttl;
1338 iph->protocol = sk->sk_protocol;
1339 iph->saddr = fl4->saddr;
1340 iph->daddr = fl4->daddr;
1341
1342 if (opt) {
1343 iph->ihl += opt->optlen>>2;
1344 ip_options_build(skb, opt, cork->addr, rt, 0);
1345 }
1346
1347 skb->priority = sk->sk_priority;
1348 skb->mark = sk->sk_mark;
1349 /*
1350 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec
1351 * on dst refcount
1352 */
1353 cork->dst = NULL;
1354 skb_dst_set(skb, &rt->dst);
1355
1356 if (iph->protocol == IPPROTO_ICMP)
1357 icmp_out_count(net, ((struct icmphdr *)
1358 skb_transport_header(skb))->type);
1359
1360 ip_cork_release(cork);
1361out:
1362 return skb;
1363}
1364
1365int ip_send_skb(struct sk_buff *skb)
1366{
1367 struct net *net = sock_net(skb->sk);
1368 int err;
1369
1370 err = ip_local_out(skb);
1371 if (err) {
1372 if (err > 0)
1373 err = net_xmit_errno(err);
1374 if (err)
1375 IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS);
1376 }
1377
1378 return err;
1379}
1380
1381int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4)
1382{
1383 struct sk_buff *skb;
1384
1385 skb = ip_finish_skb(sk, fl4);
1386 if (!skb)
1387 return 0;
1388
1389 /* Netfilter gets whole the not fragmented skb. */
1390 return ip_send_skb(skb);
1391}
1392
1393/*
1394 * Throw away all pending data on the socket.
1395 */
1396static void __ip_flush_pending_frames(struct sock *sk,
1397 struct sk_buff_head *queue,
1398 struct inet_cork *cork)
1399{
1400 struct sk_buff *skb;
1401
1402 while ((skb = __skb_dequeue_tail(queue)) != NULL)
1403 kfree_skb(skb);
1404
1405 ip_cork_release(cork);
1406}
1407
1408void ip_flush_pending_frames(struct sock *sk)
1409{
1410 __ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork.base);
1411}
1412
1413struct sk_buff *ip_make_skb(struct sock *sk,
1414 struct flowi4 *fl4,
1415 int getfrag(void *from, char *to, int offset,
1416 int len, int odd, struct sk_buff *skb),
1417 void *from, int length, int transhdrlen,
1418 struct ipcm_cookie *ipc, struct rtable **rtp,
1419 unsigned int flags)
1420{
1421 struct inet_cork cork;
1422 struct sk_buff_head queue;
1423 int err;
1424
1425 if (flags & MSG_PROBE)
1426 return NULL;
1427
1428 __skb_queue_head_init(&queue);
1429
1430 cork.flags = 0;
1431 cork.addr = 0;
1432 cork.opt = NULL;
1433 err = ip_setup_cork(sk, &cork, ipc, rtp);
1434 if (err)
1435 return ERR_PTR(err);
1436
1437 err = __ip_append_data(sk, fl4, &queue, &cork, getfrag,
1438 from, length, transhdrlen, flags);
1439 if (err) {
1440 __ip_flush_pending_frames(sk, &queue, &cork);
1441 return ERR_PTR(err);
1442 }
1443
1444 return __ip_make_skb(sk, fl4, &queue, &cork);
1445}
1446
1447/*
1448 * Fetch data from kernel space and fill in checksum if needed.
1449 */
1450static int ip_reply_glue_bits(void *dptr, char *to, int offset,
1451 int len, int odd, struct sk_buff *skb)
1452{
1453 __wsum csum;
1454
1455 csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0);
1456 skb->csum = csum_block_add(skb->csum, csum, odd);
1457 return 0;
1458}
1459
1460/*
1461 * Generic function to send a packet as reply to another packet.
1462 * Used to send TCP resets so far. ICMP should use this function too.
1463 *
1464 * Should run single threaded per socket because it uses the sock
1465 * structure to pass arguments.
1466 */
1467void ip_send_reply(struct sock *sk, struct sk_buff *skb, __be32 daddr,
1468 struct ip_reply_arg *arg, unsigned int len)
1469{
1470 struct inet_sock *inet = inet_sk(sk);
1471 struct ip_options_data replyopts;
1472 struct ipcm_cookie ipc;
1473 struct flowi4 fl4;
1474 struct rtable *rt = skb_rtable(skb);
1475
1476 if (ip_options_echo(&replyopts.opt.opt, skb))
1477 return;
1478
1479 ipc.addr = daddr;
1480 ipc.opt = NULL;
1481 ipc.tx_flags = 0;
1482
1483 if (replyopts.opt.opt.optlen) {
1484 ipc.opt = &replyopts.opt;
1485
1486 if (replyopts.opt.opt.srr)
1487 daddr = replyopts.opt.opt.faddr;
1488 }
1489
1490 flowi4_init_output(&fl4, arg->bound_dev_if, 0,
1491 RT_TOS(ip_hdr(skb)->tos),
1492 RT_SCOPE_UNIVERSE, sk->sk_protocol,
1493 ip_reply_arg_flowi_flags(arg),
1494 daddr, rt->rt_spec_dst,
1495 tcp_hdr(skb)->source, tcp_hdr(skb)->dest);
1496 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
1497 rt = ip_route_output_key(sock_net(sk), &fl4);
1498 if (IS_ERR(rt))
1499 return;
1500
1501 /* And let IP do all the hard work.
1502
1503 This chunk is not reenterable, hence spinlock.
1504 Note that it uses the fact, that this function is called
1505 with locally disabled BH and that sk cannot be already spinlocked.
1506 */
1507 bh_lock_sock(sk);
1508 inet->tos = ip_hdr(skb)->tos;
1509 sk->sk_priority = skb->priority;
1510 sk->sk_protocol = ip_hdr(skb)->protocol;
1511 sk->sk_bound_dev_if = arg->bound_dev_if;
1512 ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base, len, 0,
1513 &ipc, &rt, MSG_DONTWAIT);
1514 if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
1515 if (arg->csumoffset >= 0)
1516 *((__sum16 *)skb_transport_header(skb) +
1517 arg->csumoffset) = csum_fold(csum_add(skb->csum,
1518 arg->csum));
1519 skb->ip_summed = CHECKSUM_NONE;
1520 ip_push_pending_frames(sk, &fl4);
1521 }
1522
1523 bh_unlock_sock(sk);
1524
1525 ip_rt_put(rt);
1526}
1527
1528void __init ip_init(void)
1529{
1530 ip_rt_init();
1531 inet_initpeers();
1532
1533#if defined(CONFIG_IP_MULTICAST) && defined(CONFIG_PROC_FS)
1534 igmp_mc_proc_init();
1535#endif
1536}