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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/inetpeer.h>
77#include <net/inet_ecn.h>
78#include <net/lwtunnel.h>
79#include <linux/bpf-cgroup.h>
80#include <linux/igmp.h>
81#include <linux/netfilter_ipv4.h>
82#include <linux/netfilter_bridge.h>
83#include <linux/netlink.h>
84#include <linux/tcp.h>
85
86static int
87ip_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
88 unsigned int mtu,
89 int (*output)(struct net *, struct sock *, struct sk_buff *));
90
91/* Generate a checksum for an outgoing IP datagram. */
92void ip_send_check(struct iphdr *iph)
93{
94 iph->check = 0;
95 iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
96}
97EXPORT_SYMBOL(ip_send_check);
98
99int __ip_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
100{
101 struct iphdr *iph = ip_hdr(skb);
102
103 iph->tot_len = htons(skb->len);
104 ip_send_check(iph);
105
106 /* if egress device is enslaved to an L3 master device pass the
107 * skb to its handler for processing
108 */
109 skb = l3mdev_ip_out(sk, skb);
110 if (unlikely(!skb))
111 return 0;
112
113 skb->protocol = htons(ETH_P_IP);
114
115 return nf_hook(NFPROTO_IPV4, NF_INET_LOCAL_OUT,
116 net, sk, skb, NULL, skb_dst(skb)->dev,
117 dst_output);
118}
119
120int ip_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
121{
122 int err;
123
124 err = __ip_local_out(net, sk, skb);
125 if (likely(err == 1))
126 err = dst_output(net, sk, skb);
127
128 return err;
129}
130EXPORT_SYMBOL_GPL(ip_local_out);
131
132static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst)
133{
134 int ttl = inet->uc_ttl;
135
136 if (ttl < 0)
137 ttl = ip4_dst_hoplimit(dst);
138 return ttl;
139}
140
141/*
142 * Add an ip header to a skbuff and send it out.
143 *
144 */
145int ip_build_and_send_pkt(struct sk_buff *skb, const struct sock *sk,
146 __be32 saddr, __be32 daddr, struct ip_options_rcu *opt,
147 u8 tos)
148{
149 struct inet_sock *inet = inet_sk(sk);
150 struct rtable *rt = skb_rtable(skb);
151 struct net *net = sock_net(sk);
152 struct iphdr *iph;
153
154 /* Build the IP header. */
155 skb_push(skb, sizeof(struct iphdr) + (opt ? opt->opt.optlen : 0));
156 skb_reset_network_header(skb);
157 iph = ip_hdr(skb);
158 iph->version = 4;
159 iph->ihl = 5;
160 iph->tos = tos;
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 /* Do not bother generating IPID for small packets (eg SYNACK) */
166 if (skb->len <= IPV4_MIN_MTU || ip_dont_fragment(sk, &rt->dst)) {
167 iph->frag_off = htons(IP_DF);
168 iph->id = 0;
169 } else {
170 iph->frag_off = 0;
171 /* TCP packets here are SYNACK with fat IPv4/TCP options.
172 * Avoid using the hashed IP ident generator.
173 */
174 if (sk->sk_protocol == IPPROTO_TCP)
175 iph->id = (__force __be16)get_random_u16();
176 else
177 __ip_select_ident(net, iph, 1);
178 }
179
180 if (opt && opt->opt.optlen) {
181 iph->ihl += opt->opt.optlen>>2;
182 ip_options_build(skb, &opt->opt, daddr, rt);
183 }
184
185 skb->priority = sk->sk_priority;
186 if (!skb->mark)
187 skb->mark = sk->sk_mark;
188
189 /* Send it out. */
190 return ip_local_out(net, skb->sk, skb);
191}
192EXPORT_SYMBOL_GPL(ip_build_and_send_pkt);
193
194static int ip_finish_output2(struct net *net, struct sock *sk, struct sk_buff *skb)
195{
196 struct dst_entry *dst = skb_dst(skb);
197 struct rtable *rt = (struct rtable *)dst;
198 struct net_device *dev = dst->dev;
199 unsigned int hh_len = LL_RESERVED_SPACE(dev);
200 struct neighbour *neigh;
201 bool is_v6gw = false;
202
203 if (rt->rt_type == RTN_MULTICAST) {
204 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUTMCAST, skb->len);
205 } else if (rt->rt_type == RTN_BROADCAST)
206 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUTBCAST, skb->len);
207
208 if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) {
209 skb = skb_expand_head(skb, hh_len);
210 if (!skb)
211 return -ENOMEM;
212 }
213
214 if (lwtunnel_xmit_redirect(dst->lwtstate)) {
215 int res = lwtunnel_xmit(skb);
216
217 if (res < 0 || res == LWTUNNEL_XMIT_DONE)
218 return res;
219 }
220
221 rcu_read_lock_bh();
222 neigh = ip_neigh_for_gw(rt, skb, &is_v6gw);
223 if (!IS_ERR(neigh)) {
224 int res;
225
226 sock_confirm_neigh(skb, neigh);
227 /* if crossing protocols, can not use the cached header */
228 res = neigh_output(neigh, skb, is_v6gw);
229 rcu_read_unlock_bh();
230 return res;
231 }
232 rcu_read_unlock_bh();
233
234 net_dbg_ratelimited("%s: No header cache and no neighbour!\n",
235 __func__);
236 kfree_skb_reason(skb, SKB_DROP_REASON_NEIGH_CREATEFAIL);
237 return -EINVAL;
238}
239
240static int ip_finish_output_gso(struct net *net, struct sock *sk,
241 struct sk_buff *skb, unsigned int mtu)
242{
243 struct sk_buff *segs, *nskb;
244 netdev_features_t features;
245 int ret = 0;
246
247 /* common case: seglen is <= mtu
248 */
249 if (skb_gso_validate_network_len(skb, mtu))
250 return ip_finish_output2(net, sk, skb);
251
252 /* Slowpath - GSO segment length exceeds the egress MTU.
253 *
254 * This can happen in several cases:
255 * - Forwarding of a TCP GRO skb, when DF flag is not set.
256 * - Forwarding of an skb that arrived on a virtualization interface
257 * (virtio-net/vhost/tap) with TSO/GSO size set by other network
258 * stack.
259 * - Local GSO skb transmitted on an NETIF_F_TSO tunnel stacked over an
260 * interface with a smaller MTU.
261 * - Arriving GRO skb (or GSO skb in a virtualized environment) that is
262 * bridged to a NETIF_F_TSO tunnel stacked over an interface with an
263 * insufficient MTU.
264 */
265 features = netif_skb_features(skb);
266 BUILD_BUG_ON(sizeof(*IPCB(skb)) > SKB_GSO_CB_OFFSET);
267 segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK);
268 if (IS_ERR_OR_NULL(segs)) {
269 kfree_skb(skb);
270 return -ENOMEM;
271 }
272
273 consume_skb(skb);
274
275 skb_list_walk_safe(segs, segs, nskb) {
276 int err;
277
278 skb_mark_not_on_list(segs);
279 err = ip_fragment(net, sk, segs, mtu, ip_finish_output2);
280
281 if (err && ret == 0)
282 ret = err;
283 }
284
285 return ret;
286}
287
288static int __ip_finish_output(struct net *net, struct sock *sk, struct sk_buff *skb)
289{
290 unsigned int mtu;
291
292#if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
293 /* Policy lookup after SNAT yielded a new policy */
294 if (skb_dst(skb)->xfrm) {
295 IPCB(skb)->flags |= IPSKB_REROUTED;
296 return dst_output(net, sk, skb);
297 }
298#endif
299 mtu = ip_skb_dst_mtu(sk, skb);
300 if (skb_is_gso(skb))
301 return ip_finish_output_gso(net, sk, skb, mtu);
302
303 if (skb->len > mtu || IPCB(skb)->frag_max_size)
304 return ip_fragment(net, sk, skb, mtu, ip_finish_output2);
305
306 return ip_finish_output2(net, sk, skb);
307}
308
309static int ip_finish_output(struct net *net, struct sock *sk, struct sk_buff *skb)
310{
311 int ret;
312
313 ret = BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb);
314 switch (ret) {
315 case NET_XMIT_SUCCESS:
316 return __ip_finish_output(net, sk, skb);
317 case NET_XMIT_CN:
318 return __ip_finish_output(net, sk, skb) ? : ret;
319 default:
320 kfree_skb_reason(skb, SKB_DROP_REASON_BPF_CGROUP_EGRESS);
321 return ret;
322 }
323}
324
325static int ip_mc_finish_output(struct net *net, struct sock *sk,
326 struct sk_buff *skb)
327{
328 struct rtable *new_rt;
329 bool do_cn = false;
330 int ret, err;
331
332 ret = BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb);
333 switch (ret) {
334 case NET_XMIT_CN:
335 do_cn = true;
336 fallthrough;
337 case NET_XMIT_SUCCESS:
338 break;
339 default:
340 kfree_skb_reason(skb, SKB_DROP_REASON_BPF_CGROUP_EGRESS);
341 return ret;
342 }
343
344 /* Reset rt_iif so that inet_iif() will return skb->skb_iif. Setting
345 * this to non-zero causes ipi_ifindex in in_pktinfo to be overwritten,
346 * see ipv4_pktinfo_prepare().
347 */
348 new_rt = rt_dst_clone(net->loopback_dev, skb_rtable(skb));
349 if (new_rt) {
350 new_rt->rt_iif = 0;
351 skb_dst_drop(skb);
352 skb_dst_set(skb, &new_rt->dst);
353 }
354
355 err = dev_loopback_xmit(net, sk, skb);
356 return (do_cn && err) ? ret : err;
357}
358
359int ip_mc_output(struct net *net, struct sock *sk, struct sk_buff *skb)
360{
361 struct rtable *rt = skb_rtable(skb);
362 struct net_device *dev = rt->dst.dev;
363
364 /*
365 * If the indicated interface is up and running, send the packet.
366 */
367 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUT, skb->len);
368
369 skb->dev = dev;
370 skb->protocol = htons(ETH_P_IP);
371
372 /*
373 * Multicasts are looped back for other local users
374 */
375
376 if (rt->rt_flags&RTCF_MULTICAST) {
377 if (sk_mc_loop(sk)
378#ifdef CONFIG_IP_MROUTE
379 /* Small optimization: do not loopback not local frames,
380 which returned after forwarding; they will be dropped
381 by ip_mr_input in any case.
382 Note, that local frames are looped back to be delivered
383 to local recipients.
384
385 This check is duplicated in ip_mr_input at the moment.
386 */
387 &&
388 ((rt->rt_flags & RTCF_LOCAL) ||
389 !(IPCB(skb)->flags & IPSKB_FORWARDED))
390#endif
391 ) {
392 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
393 if (newskb)
394 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
395 net, sk, newskb, NULL, newskb->dev,
396 ip_mc_finish_output);
397 }
398
399 /* Multicasts with ttl 0 must not go beyond the host */
400
401 if (ip_hdr(skb)->ttl == 0) {
402 kfree_skb(skb);
403 return 0;
404 }
405 }
406
407 if (rt->rt_flags&RTCF_BROADCAST) {
408 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
409 if (newskb)
410 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
411 net, sk, newskb, NULL, newskb->dev,
412 ip_mc_finish_output);
413 }
414
415 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
416 net, sk, skb, NULL, skb->dev,
417 ip_finish_output,
418 !(IPCB(skb)->flags & IPSKB_REROUTED));
419}
420
421int ip_output(struct net *net, struct sock *sk, struct sk_buff *skb)
422{
423 struct net_device *dev = skb_dst(skb)->dev, *indev = skb->dev;
424
425 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUT, skb->len);
426
427 skb->dev = dev;
428 skb->protocol = htons(ETH_P_IP);
429
430 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
431 net, sk, skb, indev, dev,
432 ip_finish_output,
433 !(IPCB(skb)->flags & IPSKB_REROUTED));
434}
435EXPORT_SYMBOL(ip_output);
436
437/*
438 * copy saddr and daddr, possibly using 64bit load/stores
439 * Equivalent to :
440 * iph->saddr = fl4->saddr;
441 * iph->daddr = fl4->daddr;
442 */
443static void ip_copy_addrs(struct iphdr *iph, const struct flowi4 *fl4)
444{
445 BUILD_BUG_ON(offsetof(typeof(*fl4), daddr) !=
446 offsetof(typeof(*fl4), saddr) + sizeof(fl4->saddr));
447
448 iph->saddr = fl4->saddr;
449 iph->daddr = fl4->daddr;
450}
451
452/* Note: skb->sk can be different from sk, in case of tunnels */
453int __ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl,
454 __u8 tos)
455{
456 struct inet_sock *inet = inet_sk(sk);
457 struct net *net = sock_net(sk);
458 struct ip_options_rcu *inet_opt;
459 struct flowi4 *fl4;
460 struct rtable *rt;
461 struct iphdr *iph;
462 int res;
463
464 /* Skip all of this if the packet is already routed,
465 * f.e. by something like SCTP.
466 */
467 rcu_read_lock();
468 inet_opt = rcu_dereference(inet->inet_opt);
469 fl4 = &fl->u.ip4;
470 rt = skb_rtable(skb);
471 if (rt)
472 goto packet_routed;
473
474 /* Make sure we can route this packet. */
475 rt = (struct rtable *)__sk_dst_check(sk, 0);
476 if (!rt) {
477 __be32 daddr;
478
479 /* Use correct destination address if we have options. */
480 daddr = inet->inet_daddr;
481 if (inet_opt && inet_opt->opt.srr)
482 daddr = inet_opt->opt.faddr;
483
484 /* If this fails, retransmit mechanism of transport layer will
485 * keep trying until route appears or the connection times
486 * itself out.
487 */
488 rt = ip_route_output_ports(net, fl4, sk,
489 daddr, inet->inet_saddr,
490 inet->inet_dport,
491 inet->inet_sport,
492 sk->sk_protocol,
493 RT_CONN_FLAGS_TOS(sk, tos),
494 sk->sk_bound_dev_if);
495 if (IS_ERR(rt))
496 goto no_route;
497 sk_setup_caps(sk, &rt->dst);
498 }
499 skb_dst_set_noref(skb, &rt->dst);
500
501packet_routed:
502 if (inet_opt && inet_opt->opt.is_strictroute && rt->rt_uses_gateway)
503 goto no_route;
504
505 /* OK, we know where to send it, allocate and build IP header. */
506 skb_push(skb, sizeof(struct iphdr) + (inet_opt ? inet_opt->opt.optlen : 0));
507 skb_reset_network_header(skb);
508 iph = ip_hdr(skb);
509 *((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (tos & 0xff));
510 if (ip_dont_fragment(sk, &rt->dst) && !skb->ignore_df)
511 iph->frag_off = htons(IP_DF);
512 else
513 iph->frag_off = 0;
514 iph->ttl = ip_select_ttl(inet, &rt->dst);
515 iph->protocol = sk->sk_protocol;
516 ip_copy_addrs(iph, fl4);
517
518 /* Transport layer set skb->h.foo itself. */
519
520 if (inet_opt && inet_opt->opt.optlen) {
521 iph->ihl += inet_opt->opt.optlen >> 2;
522 ip_options_build(skb, &inet_opt->opt, inet->inet_daddr, rt);
523 }
524
525 ip_select_ident_segs(net, skb, sk,
526 skb_shinfo(skb)->gso_segs ?: 1);
527
528 /* TODO : should we use skb->sk here instead of sk ? */
529 skb->priority = sk->sk_priority;
530 skb->mark = sk->sk_mark;
531
532 res = ip_local_out(net, sk, skb);
533 rcu_read_unlock();
534 return res;
535
536no_route:
537 rcu_read_unlock();
538 IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
539 kfree_skb_reason(skb, SKB_DROP_REASON_IP_OUTNOROUTES);
540 return -EHOSTUNREACH;
541}
542EXPORT_SYMBOL(__ip_queue_xmit);
543
544int ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl)
545{
546 return __ip_queue_xmit(sk, skb, fl, inet_sk(sk)->tos);
547}
548EXPORT_SYMBOL(ip_queue_xmit);
549
550static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from)
551{
552 to->pkt_type = from->pkt_type;
553 to->priority = from->priority;
554 to->protocol = from->protocol;
555 to->skb_iif = from->skb_iif;
556 skb_dst_drop(to);
557 skb_dst_copy(to, from);
558 to->dev = from->dev;
559 to->mark = from->mark;
560
561 skb_copy_hash(to, from);
562
563#ifdef CONFIG_NET_SCHED
564 to->tc_index = from->tc_index;
565#endif
566 nf_copy(to, from);
567 skb_ext_copy(to, from);
568#if IS_ENABLED(CONFIG_IP_VS)
569 to->ipvs_property = from->ipvs_property;
570#endif
571 skb_copy_secmark(to, from);
572}
573
574static int ip_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
575 unsigned int mtu,
576 int (*output)(struct net *, struct sock *, struct sk_buff *))
577{
578 struct iphdr *iph = ip_hdr(skb);
579
580 if ((iph->frag_off & htons(IP_DF)) == 0)
581 return ip_do_fragment(net, sk, skb, output);
582
583 if (unlikely(!skb->ignore_df ||
584 (IPCB(skb)->frag_max_size &&
585 IPCB(skb)->frag_max_size > mtu))) {
586 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
587 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
588 htonl(mtu));
589 kfree_skb(skb);
590 return -EMSGSIZE;
591 }
592
593 return ip_do_fragment(net, sk, skb, output);
594}
595
596void ip_fraglist_init(struct sk_buff *skb, struct iphdr *iph,
597 unsigned int hlen, struct ip_fraglist_iter *iter)
598{
599 unsigned int first_len = skb_pagelen(skb);
600
601 iter->frag = skb_shinfo(skb)->frag_list;
602 skb_frag_list_init(skb);
603
604 iter->offset = 0;
605 iter->iph = iph;
606 iter->hlen = hlen;
607
608 skb->data_len = first_len - skb_headlen(skb);
609 skb->len = first_len;
610 iph->tot_len = htons(first_len);
611 iph->frag_off = htons(IP_MF);
612 ip_send_check(iph);
613}
614EXPORT_SYMBOL(ip_fraglist_init);
615
616void ip_fraglist_prepare(struct sk_buff *skb, struct ip_fraglist_iter *iter)
617{
618 unsigned int hlen = iter->hlen;
619 struct iphdr *iph = iter->iph;
620 struct sk_buff *frag;
621
622 frag = iter->frag;
623 frag->ip_summed = CHECKSUM_NONE;
624 skb_reset_transport_header(frag);
625 __skb_push(frag, hlen);
626 skb_reset_network_header(frag);
627 memcpy(skb_network_header(frag), iph, hlen);
628 iter->iph = ip_hdr(frag);
629 iph = iter->iph;
630 iph->tot_len = htons(frag->len);
631 ip_copy_metadata(frag, skb);
632 iter->offset += skb->len - hlen;
633 iph->frag_off = htons(iter->offset >> 3);
634 if (frag->next)
635 iph->frag_off |= htons(IP_MF);
636 /* Ready, complete checksum */
637 ip_send_check(iph);
638}
639EXPORT_SYMBOL(ip_fraglist_prepare);
640
641void ip_frag_init(struct sk_buff *skb, unsigned int hlen,
642 unsigned int ll_rs, unsigned int mtu, bool DF,
643 struct ip_frag_state *state)
644{
645 struct iphdr *iph = ip_hdr(skb);
646
647 state->DF = DF;
648 state->hlen = hlen;
649 state->ll_rs = ll_rs;
650 state->mtu = mtu;
651
652 state->left = skb->len - hlen; /* Space per frame */
653 state->ptr = hlen; /* Where to start from */
654
655 state->offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3;
656 state->not_last_frag = iph->frag_off & htons(IP_MF);
657}
658EXPORT_SYMBOL(ip_frag_init);
659
660static void ip_frag_ipcb(struct sk_buff *from, struct sk_buff *to,
661 bool first_frag)
662{
663 /* Copy the flags to each fragment. */
664 IPCB(to)->flags = IPCB(from)->flags;
665
666 /* ANK: dirty, but effective trick. Upgrade options only if
667 * the segment to be fragmented was THE FIRST (otherwise,
668 * options are already fixed) and make it ONCE
669 * on the initial skb, so that all the following fragments
670 * will inherit fixed options.
671 */
672 if (first_frag)
673 ip_options_fragment(from);
674}
675
676struct sk_buff *ip_frag_next(struct sk_buff *skb, struct ip_frag_state *state)
677{
678 unsigned int len = state->left;
679 struct sk_buff *skb2;
680 struct iphdr *iph;
681
682 /* IF: it doesn't fit, use 'mtu' - the data space left */
683 if (len > state->mtu)
684 len = state->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 < state->left) {
688 len &= ~7;
689 }
690
691 /* Allocate buffer */
692 skb2 = alloc_skb(len + state->hlen + state->ll_rs, GFP_ATOMIC);
693 if (!skb2)
694 return ERR_PTR(-ENOMEM);
695
696 /*
697 * Set up data on packet
698 */
699
700 ip_copy_metadata(skb2, skb);
701 skb_reserve(skb2, state->ll_rs);
702 skb_put(skb2, len + state->hlen);
703 skb_reset_network_header(skb2);
704 skb2->transport_header = skb2->network_header + state->hlen;
705
706 /*
707 * Charge the memory for the fragment to any owner
708 * it might possess
709 */
710
711 if (skb->sk)
712 skb_set_owner_w(skb2, skb->sk);
713
714 /*
715 * Copy the packet header into the new buffer.
716 */
717
718 skb_copy_from_linear_data(skb, skb_network_header(skb2), state->hlen);
719
720 /*
721 * Copy a block of the IP datagram.
722 */
723 if (skb_copy_bits(skb, state->ptr, skb_transport_header(skb2), len))
724 BUG();
725 state->left -= len;
726
727 /*
728 * Fill in the new header fields.
729 */
730 iph = ip_hdr(skb2);
731 iph->frag_off = htons((state->offset >> 3));
732 if (state->DF)
733 iph->frag_off |= htons(IP_DF);
734
735 /*
736 * Added AC : If we are fragmenting a fragment that's not the
737 * last fragment then keep MF on each bit
738 */
739 if (state->left > 0 || state->not_last_frag)
740 iph->frag_off |= htons(IP_MF);
741 state->ptr += len;
742 state->offset += len;
743
744 iph->tot_len = htons(len + state->hlen);
745
746 ip_send_check(iph);
747
748 return skb2;
749}
750EXPORT_SYMBOL(ip_frag_next);
751
752/*
753 * This IP datagram is too large to be sent in one piece. Break it up into
754 * smaller pieces (each of size equal to IP header plus
755 * a block of the data of the original IP data part) that will yet fit in a
756 * single device frame, and queue such a frame for sending.
757 */
758
759int ip_do_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
760 int (*output)(struct net *, struct sock *, struct sk_buff *))
761{
762 struct iphdr *iph;
763 struct sk_buff *skb2;
764 bool mono_delivery_time = skb->mono_delivery_time;
765 struct rtable *rt = skb_rtable(skb);
766 unsigned int mtu, hlen, ll_rs;
767 struct ip_fraglist_iter iter;
768 ktime_t tstamp = skb->tstamp;
769 struct ip_frag_state state;
770 int err = 0;
771
772 /* for offloaded checksums cleanup checksum before fragmentation */
773 if (skb->ip_summed == CHECKSUM_PARTIAL &&
774 (err = skb_checksum_help(skb)))
775 goto fail;
776
777 /*
778 * Point into the IP datagram header.
779 */
780
781 iph = ip_hdr(skb);
782
783 mtu = ip_skb_dst_mtu(sk, skb);
784 if (IPCB(skb)->frag_max_size && IPCB(skb)->frag_max_size < mtu)
785 mtu = IPCB(skb)->frag_max_size;
786
787 /*
788 * Setup starting values.
789 */
790
791 hlen = iph->ihl * 4;
792 mtu = mtu - hlen; /* Size of data space */
793 IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE;
794 ll_rs = LL_RESERVED_SPACE(rt->dst.dev);
795
796 /* When frag_list is given, use it. First, check its validity:
797 * some transformers could create wrong frag_list or break existing
798 * one, it is not prohibited. In this case fall back to copying.
799 *
800 * LATER: this step can be merged to real generation of fragments,
801 * we can switch to copy when see the first bad fragment.
802 */
803 if (skb_has_frag_list(skb)) {
804 struct sk_buff *frag, *frag2;
805 unsigned int first_len = skb_pagelen(skb);
806
807 if (first_len - hlen > mtu ||
808 ((first_len - hlen) & 7) ||
809 ip_is_fragment(iph) ||
810 skb_cloned(skb) ||
811 skb_headroom(skb) < ll_rs)
812 goto slow_path;
813
814 skb_walk_frags(skb, frag) {
815 /* Correct geometry. */
816 if (frag->len > mtu ||
817 ((frag->len & 7) && frag->next) ||
818 skb_headroom(frag) < hlen + ll_rs)
819 goto slow_path_clean;
820
821 /* Partially cloned skb? */
822 if (skb_shared(frag))
823 goto slow_path_clean;
824
825 BUG_ON(frag->sk);
826 if (skb->sk) {
827 frag->sk = skb->sk;
828 frag->destructor = sock_wfree;
829 }
830 skb->truesize -= frag->truesize;
831 }
832
833 /* Everything is OK. Generate! */
834 ip_fraglist_init(skb, iph, hlen, &iter);
835
836 for (;;) {
837 /* Prepare header of the next frame,
838 * before previous one went down. */
839 if (iter.frag) {
840 bool first_frag = (iter.offset == 0);
841
842 IPCB(iter.frag)->flags = IPCB(skb)->flags;
843 ip_fraglist_prepare(skb, &iter);
844 if (first_frag && IPCB(skb)->opt.optlen) {
845 /* ipcb->opt is not populated for frags
846 * coming from __ip_make_skb(),
847 * ip_options_fragment() needs optlen
848 */
849 IPCB(iter.frag)->opt.optlen =
850 IPCB(skb)->opt.optlen;
851 ip_options_fragment(iter.frag);
852 ip_send_check(iter.iph);
853 }
854 }
855
856 skb_set_delivery_time(skb, tstamp, mono_delivery_time);
857 err = output(net, sk, skb);
858
859 if (!err)
860 IP_INC_STATS(net, IPSTATS_MIB_FRAGCREATES);
861 if (err || !iter.frag)
862 break;
863
864 skb = ip_fraglist_next(&iter);
865 }
866
867 if (err == 0) {
868 IP_INC_STATS(net, IPSTATS_MIB_FRAGOKS);
869 return 0;
870 }
871
872 kfree_skb_list(iter.frag);
873
874 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
875 return err;
876
877slow_path_clean:
878 skb_walk_frags(skb, frag2) {
879 if (frag2 == frag)
880 break;
881 frag2->sk = NULL;
882 frag2->destructor = NULL;
883 skb->truesize += frag2->truesize;
884 }
885 }
886
887slow_path:
888 /*
889 * Fragment the datagram.
890 */
891
892 ip_frag_init(skb, hlen, ll_rs, mtu, IPCB(skb)->flags & IPSKB_FRAG_PMTU,
893 &state);
894
895 /*
896 * Keep copying data until we run out.
897 */
898
899 while (state.left > 0) {
900 bool first_frag = (state.offset == 0);
901
902 skb2 = ip_frag_next(skb, &state);
903 if (IS_ERR(skb2)) {
904 err = PTR_ERR(skb2);
905 goto fail;
906 }
907 ip_frag_ipcb(skb, skb2, first_frag);
908
909 /*
910 * Put this fragment into the sending queue.
911 */
912 skb_set_delivery_time(skb2, tstamp, mono_delivery_time);
913 err = output(net, sk, skb2);
914 if (err)
915 goto fail;
916
917 IP_INC_STATS(net, IPSTATS_MIB_FRAGCREATES);
918 }
919 consume_skb(skb);
920 IP_INC_STATS(net, IPSTATS_MIB_FRAGOKS);
921 return err;
922
923fail:
924 kfree_skb(skb);
925 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
926 return err;
927}
928EXPORT_SYMBOL(ip_do_fragment);
929
930int
931ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
932{
933 struct msghdr *msg = from;
934
935 if (skb->ip_summed == CHECKSUM_PARTIAL) {
936 if (!copy_from_iter_full(to, len, &msg->msg_iter))
937 return -EFAULT;
938 } else {
939 __wsum csum = 0;
940 if (!csum_and_copy_from_iter_full(to, len, &csum, &msg->msg_iter))
941 return -EFAULT;
942 skb->csum = csum_block_add(skb->csum, csum, odd);
943 }
944 return 0;
945}
946EXPORT_SYMBOL(ip_generic_getfrag);
947
948static inline __wsum
949csum_page(struct page *page, int offset, int copy)
950{
951 char *kaddr;
952 __wsum csum;
953 kaddr = kmap(page);
954 csum = csum_partial(kaddr + offset, copy, 0);
955 kunmap(page);
956 return csum;
957}
958
959static int __ip_append_data(struct sock *sk,
960 struct flowi4 *fl4,
961 struct sk_buff_head *queue,
962 struct inet_cork *cork,
963 struct page_frag *pfrag,
964 int getfrag(void *from, char *to, int offset,
965 int len, int odd, struct sk_buff *skb),
966 void *from, int length, int transhdrlen,
967 unsigned int flags)
968{
969 struct inet_sock *inet = inet_sk(sk);
970 struct ubuf_info *uarg = NULL;
971 struct sk_buff *skb;
972 struct ip_options *opt = cork->opt;
973 int hh_len;
974 int exthdrlen;
975 int mtu;
976 int copy;
977 int err;
978 int offset = 0;
979 bool zc = false;
980 unsigned int maxfraglen, fragheaderlen, maxnonfragsize;
981 int csummode = CHECKSUM_NONE;
982 struct rtable *rt = (struct rtable *)cork->dst;
983 unsigned int wmem_alloc_delta = 0;
984 bool paged, extra_uref = false;
985 u32 tskey = 0;
986
987 skb = skb_peek_tail(queue);
988
989 exthdrlen = !skb ? rt->dst.header_len : 0;
990 mtu = cork->gso_size ? IP_MAX_MTU : cork->fragsize;
991 paged = !!cork->gso_size;
992
993 if (cork->tx_flags & SKBTX_ANY_SW_TSTAMP &&
994 sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID)
995 tskey = atomic_inc_return(&sk->sk_tskey) - 1;
996
997 hh_len = LL_RESERVED_SPACE(rt->dst.dev);
998
999 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
1000 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
1001 maxnonfragsize = ip_sk_ignore_df(sk) ? IP_MAX_MTU : mtu;
1002
1003 if (cork->length + length > maxnonfragsize - fragheaderlen) {
1004 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
1005 mtu - (opt ? opt->optlen : 0));
1006 return -EMSGSIZE;
1007 }
1008
1009 /*
1010 * transhdrlen > 0 means that this is the first fragment and we wish
1011 * it won't be fragmented in the future.
1012 */
1013 if (transhdrlen &&
1014 length + fragheaderlen <= mtu &&
1015 rt->dst.dev->features & (NETIF_F_HW_CSUM | NETIF_F_IP_CSUM) &&
1016 (!(flags & MSG_MORE) || cork->gso_size) &&
1017 (!exthdrlen || (rt->dst.dev->features & NETIF_F_HW_ESP_TX_CSUM)))
1018 csummode = CHECKSUM_PARTIAL;
1019
1020 if ((flags & MSG_ZEROCOPY) && length) {
1021 struct msghdr *msg = from;
1022
1023 if (getfrag == ip_generic_getfrag && msg->msg_ubuf) {
1024 if (skb_zcopy(skb) && msg->msg_ubuf != skb_zcopy(skb))
1025 return -EINVAL;
1026
1027 /* Leave uarg NULL if can't zerocopy, callers should
1028 * be able to handle it.
1029 */
1030 if ((rt->dst.dev->features & NETIF_F_SG) &&
1031 csummode == CHECKSUM_PARTIAL) {
1032 paged = true;
1033 zc = true;
1034 uarg = msg->msg_ubuf;
1035 }
1036 } else if (sock_flag(sk, SOCK_ZEROCOPY)) {
1037 uarg = msg_zerocopy_realloc(sk, length, skb_zcopy(skb));
1038 if (!uarg)
1039 return -ENOBUFS;
1040 extra_uref = !skb_zcopy(skb); /* only ref on new uarg */
1041 if (rt->dst.dev->features & NETIF_F_SG &&
1042 csummode == CHECKSUM_PARTIAL) {
1043 paged = true;
1044 zc = true;
1045 } else {
1046 uarg_to_msgzc(uarg)->zerocopy = 0;
1047 skb_zcopy_set(skb, uarg, &extra_uref);
1048 }
1049 }
1050 }
1051
1052 cork->length += length;
1053
1054 /* So, what's going on in the loop below?
1055 *
1056 * We use calculated fragment length to generate chained skb,
1057 * each of segments is IP fragment ready for sending to network after
1058 * adding appropriate IP header.
1059 */
1060
1061 if (!skb)
1062 goto alloc_new_skb;
1063
1064 while (length > 0) {
1065 /* Check if the remaining data fits into current packet. */
1066 copy = mtu - skb->len;
1067 if (copy < length)
1068 copy = maxfraglen - skb->len;
1069 if (copy <= 0) {
1070 char *data;
1071 unsigned int datalen;
1072 unsigned int fraglen;
1073 unsigned int fraggap;
1074 unsigned int alloclen, alloc_extra;
1075 unsigned int pagedlen;
1076 struct sk_buff *skb_prev;
1077alloc_new_skb:
1078 skb_prev = skb;
1079 if (skb_prev)
1080 fraggap = skb_prev->len - maxfraglen;
1081 else
1082 fraggap = 0;
1083
1084 /*
1085 * If remaining data exceeds the mtu,
1086 * we know we need more fragment(s).
1087 */
1088 datalen = length + fraggap;
1089 if (datalen > mtu - fragheaderlen)
1090 datalen = maxfraglen - fragheaderlen;
1091 fraglen = datalen + fragheaderlen;
1092 pagedlen = 0;
1093
1094 alloc_extra = hh_len + 15;
1095 alloc_extra += exthdrlen;
1096
1097 /* The last fragment gets additional space at tail.
1098 * Note, with MSG_MORE we overallocate on fragments,
1099 * because we have no idea what fragment will be
1100 * the last.
1101 */
1102 if (datalen == length + fraggap)
1103 alloc_extra += rt->dst.trailer_len;
1104
1105 if ((flags & MSG_MORE) &&
1106 !(rt->dst.dev->features&NETIF_F_SG))
1107 alloclen = mtu;
1108 else if (!paged &&
1109 (fraglen + alloc_extra < SKB_MAX_ALLOC ||
1110 !(rt->dst.dev->features & NETIF_F_SG)))
1111 alloclen = fraglen;
1112 else {
1113 alloclen = fragheaderlen + transhdrlen;
1114 pagedlen = datalen - transhdrlen;
1115 }
1116
1117 alloclen += alloc_extra;
1118
1119 if (transhdrlen) {
1120 skb = sock_alloc_send_skb(sk, alloclen,
1121 (flags & MSG_DONTWAIT), &err);
1122 } else {
1123 skb = NULL;
1124 if (refcount_read(&sk->sk_wmem_alloc) + wmem_alloc_delta <=
1125 2 * sk->sk_sndbuf)
1126 skb = alloc_skb(alloclen,
1127 sk->sk_allocation);
1128 if (unlikely(!skb))
1129 err = -ENOBUFS;
1130 }
1131 if (!skb)
1132 goto error;
1133
1134 /*
1135 * Fill in the control structures
1136 */
1137 skb->ip_summed = csummode;
1138 skb->csum = 0;
1139 skb_reserve(skb, hh_len);
1140
1141 /*
1142 * Find where to start putting bytes.
1143 */
1144 data = skb_put(skb, fraglen + exthdrlen - pagedlen);
1145 skb_set_network_header(skb, exthdrlen);
1146 skb->transport_header = (skb->network_header +
1147 fragheaderlen);
1148 data += fragheaderlen + exthdrlen;
1149
1150 if (fraggap) {
1151 skb->csum = skb_copy_and_csum_bits(
1152 skb_prev, maxfraglen,
1153 data + transhdrlen, fraggap);
1154 skb_prev->csum = csum_sub(skb_prev->csum,
1155 skb->csum);
1156 data += fraggap;
1157 pskb_trim_unique(skb_prev, maxfraglen);
1158 }
1159
1160 copy = datalen - transhdrlen - fraggap - pagedlen;
1161 if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) {
1162 err = -EFAULT;
1163 kfree_skb(skb);
1164 goto error;
1165 }
1166
1167 offset += copy;
1168 length -= copy + transhdrlen;
1169 transhdrlen = 0;
1170 exthdrlen = 0;
1171 csummode = CHECKSUM_NONE;
1172
1173 /* only the initial fragment is time stamped */
1174 skb_shinfo(skb)->tx_flags = cork->tx_flags;
1175 cork->tx_flags = 0;
1176 skb_shinfo(skb)->tskey = tskey;
1177 tskey = 0;
1178 skb_zcopy_set(skb, uarg, &extra_uref);
1179
1180 if ((flags & MSG_CONFIRM) && !skb_prev)
1181 skb_set_dst_pending_confirm(skb, 1);
1182
1183 /*
1184 * Put the packet on the pending queue.
1185 */
1186 if (!skb->destructor) {
1187 skb->destructor = sock_wfree;
1188 skb->sk = sk;
1189 wmem_alloc_delta += skb->truesize;
1190 }
1191 __skb_queue_tail(queue, skb);
1192 continue;
1193 }
1194
1195 if (copy > length)
1196 copy = length;
1197
1198 if (!(rt->dst.dev->features&NETIF_F_SG) &&
1199 skb_tailroom(skb) >= copy) {
1200 unsigned int off;
1201
1202 off = skb->len;
1203 if (getfrag(from, skb_put(skb, copy),
1204 offset, copy, off, skb) < 0) {
1205 __skb_trim(skb, off);
1206 err = -EFAULT;
1207 goto error;
1208 }
1209 } else if (!zc) {
1210 int i = skb_shinfo(skb)->nr_frags;
1211
1212 err = -ENOMEM;
1213 if (!sk_page_frag_refill(sk, pfrag))
1214 goto error;
1215
1216 skb_zcopy_downgrade_managed(skb);
1217 if (!skb_can_coalesce(skb, i, pfrag->page,
1218 pfrag->offset)) {
1219 err = -EMSGSIZE;
1220 if (i == MAX_SKB_FRAGS)
1221 goto error;
1222
1223 __skb_fill_page_desc(skb, i, pfrag->page,
1224 pfrag->offset, 0);
1225 skb_shinfo(skb)->nr_frags = ++i;
1226 get_page(pfrag->page);
1227 }
1228 copy = min_t(int, copy, pfrag->size - pfrag->offset);
1229 if (getfrag(from,
1230 page_address(pfrag->page) + pfrag->offset,
1231 offset, copy, skb->len, skb) < 0)
1232 goto error_efault;
1233
1234 pfrag->offset += copy;
1235 skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
1236 skb_len_add(skb, copy);
1237 wmem_alloc_delta += copy;
1238 } else {
1239 err = skb_zerocopy_iter_dgram(skb, from, copy);
1240 if (err < 0)
1241 goto error;
1242 }
1243 offset += copy;
1244 length -= copy;
1245 }
1246
1247 if (wmem_alloc_delta)
1248 refcount_add(wmem_alloc_delta, &sk->sk_wmem_alloc);
1249 return 0;
1250
1251error_efault:
1252 err = -EFAULT;
1253error:
1254 net_zcopy_put_abort(uarg, extra_uref);
1255 cork->length -= length;
1256 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1257 refcount_add(wmem_alloc_delta, &sk->sk_wmem_alloc);
1258 return err;
1259}
1260
1261static int ip_setup_cork(struct sock *sk, struct inet_cork *cork,
1262 struct ipcm_cookie *ipc, struct rtable **rtp)
1263{
1264 struct ip_options_rcu *opt;
1265 struct rtable *rt;
1266
1267 rt = *rtp;
1268 if (unlikely(!rt))
1269 return -EFAULT;
1270
1271 /*
1272 * setup for corking.
1273 */
1274 opt = ipc->opt;
1275 if (opt) {
1276 if (!cork->opt) {
1277 cork->opt = kmalloc(sizeof(struct ip_options) + 40,
1278 sk->sk_allocation);
1279 if (unlikely(!cork->opt))
1280 return -ENOBUFS;
1281 }
1282 memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen);
1283 cork->flags |= IPCORK_OPT;
1284 cork->addr = ipc->addr;
1285 }
1286
1287 cork->fragsize = ip_sk_use_pmtu(sk) ?
1288 dst_mtu(&rt->dst) : READ_ONCE(rt->dst.dev->mtu);
1289
1290 if (!inetdev_valid_mtu(cork->fragsize))
1291 return -ENETUNREACH;
1292
1293 cork->gso_size = ipc->gso_size;
1294
1295 cork->dst = &rt->dst;
1296 /* We stole this route, caller should not release it. */
1297 *rtp = NULL;
1298
1299 cork->length = 0;
1300 cork->ttl = ipc->ttl;
1301 cork->tos = ipc->tos;
1302 cork->mark = ipc->sockc.mark;
1303 cork->priority = ipc->priority;
1304 cork->transmit_time = ipc->sockc.transmit_time;
1305 cork->tx_flags = 0;
1306 sock_tx_timestamp(sk, ipc->sockc.tsflags, &cork->tx_flags);
1307
1308 return 0;
1309}
1310
1311/*
1312 * ip_append_data() and ip_append_page() can make one large IP datagram
1313 * from many pieces of data. Each pieces will be holded on the socket
1314 * until ip_push_pending_frames() is called. Each piece can be a page
1315 * or non-page data.
1316 *
1317 * Not only UDP, other transport protocols - e.g. raw sockets - can use
1318 * this interface potentially.
1319 *
1320 * LATER: length must be adjusted by pad at tail, when it is required.
1321 */
1322int ip_append_data(struct sock *sk, struct flowi4 *fl4,
1323 int getfrag(void *from, char *to, int offset, int len,
1324 int odd, struct sk_buff *skb),
1325 void *from, int length, int transhdrlen,
1326 struct ipcm_cookie *ipc, struct rtable **rtp,
1327 unsigned int flags)
1328{
1329 struct inet_sock *inet = inet_sk(sk);
1330 int err;
1331
1332 if (flags&MSG_PROBE)
1333 return 0;
1334
1335 if (skb_queue_empty(&sk->sk_write_queue)) {
1336 err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp);
1337 if (err)
1338 return err;
1339 } else {
1340 transhdrlen = 0;
1341 }
1342
1343 return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base,
1344 sk_page_frag(sk), getfrag,
1345 from, length, transhdrlen, flags);
1346}
1347
1348ssize_t ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page,
1349 int offset, size_t size, int flags)
1350{
1351 struct inet_sock *inet = inet_sk(sk);
1352 struct sk_buff *skb;
1353 struct rtable *rt;
1354 struct ip_options *opt = NULL;
1355 struct inet_cork *cork;
1356 int hh_len;
1357 int mtu;
1358 int len;
1359 int err;
1360 unsigned int maxfraglen, fragheaderlen, fraggap, maxnonfragsize;
1361
1362 if (inet->hdrincl)
1363 return -EPERM;
1364
1365 if (flags&MSG_PROBE)
1366 return 0;
1367
1368 if (skb_queue_empty(&sk->sk_write_queue))
1369 return -EINVAL;
1370
1371 cork = &inet->cork.base;
1372 rt = (struct rtable *)cork->dst;
1373 if (cork->flags & IPCORK_OPT)
1374 opt = cork->opt;
1375
1376 if (!(rt->dst.dev->features & NETIF_F_SG))
1377 return -EOPNOTSUPP;
1378
1379 hh_len = LL_RESERVED_SPACE(rt->dst.dev);
1380 mtu = cork->gso_size ? IP_MAX_MTU : cork->fragsize;
1381
1382 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
1383 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
1384 maxnonfragsize = ip_sk_ignore_df(sk) ? 0xFFFF : mtu;
1385
1386 if (cork->length + size > maxnonfragsize - fragheaderlen) {
1387 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
1388 mtu - (opt ? opt->optlen : 0));
1389 return -EMSGSIZE;
1390 }
1391
1392 skb = skb_peek_tail(&sk->sk_write_queue);
1393 if (!skb)
1394 return -EINVAL;
1395
1396 cork->length += size;
1397
1398 while (size > 0) {
1399 /* Check if the remaining data fits into current packet. */
1400 len = mtu - skb->len;
1401 if (len < size)
1402 len = maxfraglen - skb->len;
1403
1404 if (len <= 0) {
1405 struct sk_buff *skb_prev;
1406 int alloclen;
1407
1408 skb_prev = skb;
1409 fraggap = skb_prev->len - maxfraglen;
1410
1411 alloclen = fragheaderlen + hh_len + fraggap + 15;
1412 skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation);
1413 if (unlikely(!skb)) {
1414 err = -ENOBUFS;
1415 goto error;
1416 }
1417
1418 /*
1419 * Fill in the control structures
1420 */
1421 skb->ip_summed = CHECKSUM_NONE;
1422 skb->csum = 0;
1423 skb_reserve(skb, hh_len);
1424
1425 /*
1426 * Find where to start putting bytes.
1427 */
1428 skb_put(skb, fragheaderlen + fraggap);
1429 skb_reset_network_header(skb);
1430 skb->transport_header = (skb->network_header +
1431 fragheaderlen);
1432 if (fraggap) {
1433 skb->csum = skb_copy_and_csum_bits(skb_prev,
1434 maxfraglen,
1435 skb_transport_header(skb),
1436 fraggap);
1437 skb_prev->csum = csum_sub(skb_prev->csum,
1438 skb->csum);
1439 pskb_trim_unique(skb_prev, maxfraglen);
1440 }
1441
1442 /*
1443 * Put the packet on the pending queue.
1444 */
1445 __skb_queue_tail(&sk->sk_write_queue, skb);
1446 continue;
1447 }
1448
1449 if (len > size)
1450 len = size;
1451
1452 if (skb_append_pagefrags(skb, page, offset, len)) {
1453 err = -EMSGSIZE;
1454 goto error;
1455 }
1456
1457 if (skb->ip_summed == CHECKSUM_NONE) {
1458 __wsum csum;
1459 csum = csum_page(page, offset, len);
1460 skb->csum = csum_block_add(skb->csum, csum, skb->len);
1461 }
1462
1463 skb_len_add(skb, len);
1464 refcount_add(len, &sk->sk_wmem_alloc);
1465 offset += len;
1466 size -= len;
1467 }
1468 return 0;
1469
1470error:
1471 cork->length -= size;
1472 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1473 return err;
1474}
1475
1476static void ip_cork_release(struct inet_cork *cork)
1477{
1478 cork->flags &= ~IPCORK_OPT;
1479 kfree(cork->opt);
1480 cork->opt = NULL;
1481 dst_release(cork->dst);
1482 cork->dst = NULL;
1483}
1484
1485/*
1486 * Combined all pending IP fragments on the socket as one IP datagram
1487 * and push them out.
1488 */
1489struct sk_buff *__ip_make_skb(struct sock *sk,
1490 struct flowi4 *fl4,
1491 struct sk_buff_head *queue,
1492 struct inet_cork *cork)
1493{
1494 struct sk_buff *skb, *tmp_skb;
1495 struct sk_buff **tail_skb;
1496 struct inet_sock *inet = inet_sk(sk);
1497 struct net *net = sock_net(sk);
1498 struct ip_options *opt = NULL;
1499 struct rtable *rt = (struct rtable *)cork->dst;
1500 struct iphdr *iph;
1501 __be16 df = 0;
1502 __u8 ttl;
1503
1504 skb = __skb_dequeue(queue);
1505 if (!skb)
1506 goto out;
1507 tail_skb = &(skb_shinfo(skb)->frag_list);
1508
1509 /* move skb->data to ip header from ext header */
1510 if (skb->data < skb_network_header(skb))
1511 __skb_pull(skb, skb_network_offset(skb));
1512 while ((tmp_skb = __skb_dequeue(queue)) != NULL) {
1513 __skb_pull(tmp_skb, skb_network_header_len(skb));
1514 *tail_skb = tmp_skb;
1515 tail_skb = &(tmp_skb->next);
1516 skb->len += tmp_skb->len;
1517 skb->data_len += tmp_skb->len;
1518 skb->truesize += tmp_skb->truesize;
1519 tmp_skb->destructor = NULL;
1520 tmp_skb->sk = NULL;
1521 }
1522
1523 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow
1524 * to fragment the frame generated here. No matter, what transforms
1525 * how transforms change size of the packet, it will come out.
1526 */
1527 skb->ignore_df = ip_sk_ignore_df(sk);
1528
1529 /* DF bit is set when we want to see DF on outgoing frames.
1530 * If ignore_df is set too, we still allow to fragment this frame
1531 * locally. */
1532 if (inet->pmtudisc == IP_PMTUDISC_DO ||
1533 inet->pmtudisc == IP_PMTUDISC_PROBE ||
1534 (skb->len <= dst_mtu(&rt->dst) &&
1535 ip_dont_fragment(sk, &rt->dst)))
1536 df = htons(IP_DF);
1537
1538 if (cork->flags & IPCORK_OPT)
1539 opt = cork->opt;
1540
1541 if (cork->ttl != 0)
1542 ttl = cork->ttl;
1543 else if (rt->rt_type == RTN_MULTICAST)
1544 ttl = inet->mc_ttl;
1545 else
1546 ttl = ip_select_ttl(inet, &rt->dst);
1547
1548 iph = ip_hdr(skb);
1549 iph->version = 4;
1550 iph->ihl = 5;
1551 iph->tos = (cork->tos != -1) ? cork->tos : inet->tos;
1552 iph->frag_off = df;
1553 iph->ttl = ttl;
1554 iph->protocol = sk->sk_protocol;
1555 ip_copy_addrs(iph, fl4);
1556 ip_select_ident(net, skb, sk);
1557
1558 if (opt) {
1559 iph->ihl += opt->optlen >> 2;
1560 ip_options_build(skb, opt, cork->addr, rt);
1561 }
1562
1563 skb->priority = (cork->tos != -1) ? cork->priority: sk->sk_priority;
1564 skb->mark = cork->mark;
1565 skb->tstamp = cork->transmit_time;
1566 /*
1567 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec
1568 * on dst refcount
1569 */
1570 cork->dst = NULL;
1571 skb_dst_set(skb, &rt->dst);
1572
1573 if (iph->protocol == IPPROTO_ICMP)
1574 icmp_out_count(net, ((struct icmphdr *)
1575 skb_transport_header(skb))->type);
1576
1577 ip_cork_release(cork);
1578out:
1579 return skb;
1580}
1581
1582int ip_send_skb(struct net *net, struct sk_buff *skb)
1583{
1584 int err;
1585
1586 err = ip_local_out(net, skb->sk, skb);
1587 if (err) {
1588 if (err > 0)
1589 err = net_xmit_errno(err);
1590 if (err)
1591 IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS);
1592 }
1593
1594 return err;
1595}
1596
1597int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4)
1598{
1599 struct sk_buff *skb;
1600
1601 skb = ip_finish_skb(sk, fl4);
1602 if (!skb)
1603 return 0;
1604
1605 /* Netfilter gets whole the not fragmented skb. */
1606 return ip_send_skb(sock_net(sk), skb);
1607}
1608
1609/*
1610 * Throw away all pending data on the socket.
1611 */
1612static void __ip_flush_pending_frames(struct sock *sk,
1613 struct sk_buff_head *queue,
1614 struct inet_cork *cork)
1615{
1616 struct sk_buff *skb;
1617
1618 while ((skb = __skb_dequeue_tail(queue)) != NULL)
1619 kfree_skb(skb);
1620
1621 ip_cork_release(cork);
1622}
1623
1624void ip_flush_pending_frames(struct sock *sk)
1625{
1626 __ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork.base);
1627}
1628
1629struct sk_buff *ip_make_skb(struct sock *sk,
1630 struct flowi4 *fl4,
1631 int getfrag(void *from, char *to, int offset,
1632 int len, int odd, struct sk_buff *skb),
1633 void *from, int length, int transhdrlen,
1634 struct ipcm_cookie *ipc, struct rtable **rtp,
1635 struct inet_cork *cork, unsigned int flags)
1636{
1637 struct sk_buff_head queue;
1638 int err;
1639
1640 if (flags & MSG_PROBE)
1641 return NULL;
1642
1643 __skb_queue_head_init(&queue);
1644
1645 cork->flags = 0;
1646 cork->addr = 0;
1647 cork->opt = NULL;
1648 err = ip_setup_cork(sk, cork, ipc, rtp);
1649 if (err)
1650 return ERR_PTR(err);
1651
1652 err = __ip_append_data(sk, fl4, &queue, cork,
1653 ¤t->task_frag, getfrag,
1654 from, length, transhdrlen, flags);
1655 if (err) {
1656 __ip_flush_pending_frames(sk, &queue, cork);
1657 return ERR_PTR(err);
1658 }
1659
1660 return __ip_make_skb(sk, fl4, &queue, cork);
1661}
1662
1663/*
1664 * Fetch data from kernel space and fill in checksum if needed.
1665 */
1666static int ip_reply_glue_bits(void *dptr, char *to, int offset,
1667 int len, int odd, struct sk_buff *skb)
1668{
1669 __wsum csum;
1670
1671 csum = csum_partial_copy_nocheck(dptr+offset, to, len);
1672 skb->csum = csum_block_add(skb->csum, csum, odd);
1673 return 0;
1674}
1675
1676/*
1677 * Generic function to send a packet as reply to another packet.
1678 * Used to send some TCP resets/acks so far.
1679 */
1680void ip_send_unicast_reply(struct sock *sk, struct sk_buff *skb,
1681 const struct ip_options *sopt,
1682 __be32 daddr, __be32 saddr,
1683 const struct ip_reply_arg *arg,
1684 unsigned int len, u64 transmit_time)
1685{
1686 struct ip_options_data replyopts;
1687 struct ipcm_cookie ipc;
1688 struct flowi4 fl4;
1689 struct rtable *rt = skb_rtable(skb);
1690 struct net *net = sock_net(sk);
1691 struct sk_buff *nskb;
1692 int err;
1693 int oif;
1694
1695 if (__ip_options_echo(net, &replyopts.opt.opt, skb, sopt))
1696 return;
1697
1698 ipcm_init(&ipc);
1699 ipc.addr = daddr;
1700 ipc.sockc.transmit_time = transmit_time;
1701
1702 if (replyopts.opt.opt.optlen) {
1703 ipc.opt = &replyopts.opt;
1704
1705 if (replyopts.opt.opt.srr)
1706 daddr = replyopts.opt.opt.faddr;
1707 }
1708
1709 oif = arg->bound_dev_if;
1710 if (!oif && netif_index_is_l3_master(net, skb->skb_iif))
1711 oif = skb->skb_iif;
1712
1713 flowi4_init_output(&fl4, oif,
1714 IP4_REPLY_MARK(net, skb->mark) ?: sk->sk_mark,
1715 RT_TOS(arg->tos),
1716 RT_SCOPE_UNIVERSE, ip_hdr(skb)->protocol,
1717 ip_reply_arg_flowi_flags(arg),
1718 daddr, saddr,
1719 tcp_hdr(skb)->source, tcp_hdr(skb)->dest,
1720 arg->uid);
1721 security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4));
1722 rt = ip_route_output_flow(net, &fl4, sk);
1723 if (IS_ERR(rt))
1724 return;
1725
1726 inet_sk(sk)->tos = arg->tos & ~INET_ECN_MASK;
1727
1728 sk->sk_protocol = ip_hdr(skb)->protocol;
1729 sk->sk_bound_dev_if = arg->bound_dev_if;
1730 sk->sk_sndbuf = READ_ONCE(sysctl_wmem_default);
1731 ipc.sockc.mark = fl4.flowi4_mark;
1732 err = ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base,
1733 len, 0, &ipc, &rt, MSG_DONTWAIT);
1734 if (unlikely(err)) {
1735 ip_flush_pending_frames(sk);
1736 goto out;
1737 }
1738
1739 nskb = skb_peek(&sk->sk_write_queue);
1740 if (nskb) {
1741 if (arg->csumoffset >= 0)
1742 *((__sum16 *)skb_transport_header(nskb) +
1743 arg->csumoffset) = csum_fold(csum_add(nskb->csum,
1744 arg->csum));
1745 nskb->ip_summed = CHECKSUM_NONE;
1746 nskb->mono_delivery_time = !!transmit_time;
1747 ip_push_pending_frames(sk, &fl4);
1748 }
1749out:
1750 ip_rt_put(rt);
1751}
1752
1753void __init ip_init(void)
1754{
1755 ip_rt_init();
1756 inet_initpeers();
1757
1758#if defined(CONFIG_IP_MULTICAST)
1759 igmp_mc_init();
1760#endif
1761}
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}