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Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
[deliverable/linux.git] / net / ipv4 / ip_output.c
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/mroute.h>
80 #include <linux/netlink.h>
81 #include <linux/tcp.h>
82
83 int sysctl_ip_default_ttl __read_mostly = IPDEFTTL;
84 EXPORT_SYMBOL(sysctl_ip_default_ttl);
85
86 static int ip_fragment(struct sock *sk, struct sk_buff *skb,
87 unsigned int mtu,
88 int (*output)(struct sock *, struct sk_buff *));
89
90 /* Generate a checksum for an outgoing IP datagram. */
91 void ip_send_check(struct iphdr *iph)
92 {
93 iph->check = 0;
94 iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
95 }
96 EXPORT_SYMBOL(ip_send_check);
97
98 static int __ip_local_out_sk(struct sock *sk, struct sk_buff *skb)
99 {
100 struct net *net = dev_net(skb_dst(skb)->dev);
101 struct iphdr *iph = ip_hdr(skb);
102
103 iph->tot_len = htons(skb->len);
104 ip_send_check(iph);
105 return nf_hook(NFPROTO_IPV4, NF_INET_LOCAL_OUT,
106 net, sk, skb, NULL, skb_dst(skb)->dev,
107 dst_output_okfn);
108 }
109
110 int __ip_local_out(struct sk_buff *skb)
111 {
112 return __ip_local_out_sk(skb->sk, skb);
113 }
114
115 int ip_local_out_sk(struct sock *sk, struct sk_buff *skb)
116 {
117 int err;
118
119 err = __ip_local_out(skb);
120 if (likely(err == 1))
121 err = dst_output(sk, skb);
122
123 return err;
124 }
125 EXPORT_SYMBOL_GPL(ip_local_out_sk);
126
127 static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst)
128 {
129 int ttl = inet->uc_ttl;
130
131 if (ttl < 0)
132 ttl = ip4_dst_hoplimit(dst);
133 return ttl;
134 }
135
136 /*
137 * Add an ip header to a skbuff and send it out.
138 *
139 */
140 int ip_build_and_send_pkt(struct sk_buff *skb, const struct sock *sk,
141 __be32 saddr, __be32 daddr, struct ip_options_rcu *opt)
142 {
143 struct inet_sock *inet = inet_sk(sk);
144 struct rtable *rt = skb_rtable(skb);
145 struct iphdr *iph;
146
147 /* Build the IP header. */
148 skb_push(skb, sizeof(struct iphdr) + (opt ? opt->opt.optlen : 0));
149 skb_reset_network_header(skb);
150 iph = ip_hdr(skb);
151 iph->version = 4;
152 iph->ihl = 5;
153 iph->tos = inet->tos;
154 iph->ttl = ip_select_ttl(inet, &rt->dst);
155 iph->daddr = (opt && opt->opt.srr ? opt->opt.faddr : daddr);
156 iph->saddr = saddr;
157 iph->protocol = sk->sk_protocol;
158 if (ip_dont_fragment(sk, &rt->dst)) {
159 iph->frag_off = htons(IP_DF);
160 iph->id = 0;
161 } else {
162 iph->frag_off = 0;
163 __ip_select_ident(sock_net(sk), iph, 1);
164 }
165
166 if (opt && opt->opt.optlen) {
167 iph->ihl += opt->opt.optlen>>2;
168 ip_options_build(skb, &opt->opt, daddr, rt, 0);
169 }
170
171 skb->priority = sk->sk_priority;
172 skb->mark = sk->sk_mark;
173
174 /* Send it out. */
175 return ip_local_out(skb);
176 }
177 EXPORT_SYMBOL_GPL(ip_build_and_send_pkt);
178
179 static int ip_finish_output2(struct sock *sk, struct sk_buff *skb)
180 {
181 struct dst_entry *dst = skb_dst(skb);
182 struct rtable *rt = (struct rtable *)dst;
183 struct net_device *dev = dst->dev;
184 struct net *net = dev_net(dev);
185 unsigned int hh_len = LL_RESERVED_SPACE(dev);
186 struct neighbour *neigh;
187 u32 nexthop;
188
189 if (rt->rt_type == RTN_MULTICAST) {
190 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUTMCAST, skb->len);
191 } else if (rt->rt_type == RTN_BROADCAST)
192 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUTBCAST, skb->len);
193
194 /* Be paranoid, rather than too clever. */
195 if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) {
196 struct sk_buff *skb2;
197
198 skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev));
199 if (!skb2) {
200 kfree_skb(skb);
201 return -ENOMEM;
202 }
203 if (skb->sk)
204 skb_set_owner_w(skb2, skb->sk);
205 consume_skb(skb);
206 skb = skb2;
207 }
208
209 rcu_read_lock_bh();
210 nexthop = (__force u32) rt_nexthop(rt, ip_hdr(skb)->daddr);
211 neigh = __ipv4_neigh_lookup_noref(dev, nexthop);
212 if (unlikely(!neigh))
213 neigh = __neigh_create(&arp_tbl, &nexthop, dev, false);
214 if (!IS_ERR(neigh)) {
215 int res = dst_neigh_output(dst, neigh, skb);
216
217 rcu_read_unlock_bh();
218 return res;
219 }
220 rcu_read_unlock_bh();
221
222 net_dbg_ratelimited("%s: No header cache and no neighbour!\n",
223 __func__);
224 kfree_skb(skb);
225 return -EINVAL;
226 }
227
228 static int ip_finish_output_gso(struct sock *sk, struct sk_buff *skb,
229 unsigned int mtu)
230 {
231 netdev_features_t features;
232 struct sk_buff *segs;
233 int ret = 0;
234
235 /* common case: locally created skb or seglen is <= mtu */
236 if (((IPCB(skb)->flags & IPSKB_FORWARDED) == 0) ||
237 skb_gso_network_seglen(skb) <= mtu)
238 return ip_finish_output2(sk, skb);
239
240 /* Slowpath - GSO segment length is exceeding the dst MTU.
241 *
242 * This can happen in two cases:
243 * 1) TCP GRO packet, DF bit not set
244 * 2) skb arrived via virtio-net, we thus get TSO/GSO skbs directly
245 * from host network stack.
246 */
247 features = netif_skb_features(skb);
248 segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK);
249 if (IS_ERR_OR_NULL(segs)) {
250 kfree_skb(skb);
251 return -ENOMEM;
252 }
253
254 consume_skb(skb);
255
256 do {
257 struct sk_buff *nskb = segs->next;
258 int err;
259
260 segs->next = NULL;
261 err = ip_fragment(sk, segs, mtu, ip_finish_output2);
262
263 if (err && ret == 0)
264 ret = err;
265 segs = nskb;
266 } while (segs);
267
268 return ret;
269 }
270
271 static int ip_finish_output(struct net *net, struct sock *sk, struct sk_buff *skb)
272 {
273 unsigned int mtu;
274
275 #if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
276 /* Policy lookup after SNAT yielded a new policy */
277 if (skb_dst(skb)->xfrm) {
278 IPCB(skb)->flags |= IPSKB_REROUTED;
279 return dst_output(sk, skb);
280 }
281 #endif
282 mtu = ip_skb_dst_mtu(skb);
283 if (skb_is_gso(skb))
284 return ip_finish_output_gso(sk, skb, mtu);
285
286 if (skb->len > mtu || (IPCB(skb)->flags & IPSKB_FRAG_PMTU))
287 return ip_fragment(sk, skb, mtu, ip_finish_output2);
288
289 return ip_finish_output2(sk, skb);
290 }
291
292 int ip_mc_output(struct sock *sk, struct sk_buff *skb)
293 {
294 struct rtable *rt = skb_rtable(skb);
295 struct net_device *dev = rt->dst.dev;
296 struct net *net = dev_net(dev);
297
298 /*
299 * If the indicated interface is up and running, send the packet.
300 */
301 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUT, skb->len);
302
303 skb->dev = dev;
304 skb->protocol = htons(ETH_P_IP);
305
306 /*
307 * Multicasts are looped back for other local users
308 */
309
310 if (rt->rt_flags&RTCF_MULTICAST) {
311 if (sk_mc_loop(sk)
312 #ifdef CONFIG_IP_MROUTE
313 /* Small optimization: do not loopback not local frames,
314 which returned after forwarding; they will be dropped
315 by ip_mr_input in any case.
316 Note, that local frames are looped back to be delivered
317 to local recipients.
318
319 This check is duplicated in ip_mr_input at the moment.
320 */
321 &&
322 ((rt->rt_flags & RTCF_LOCAL) ||
323 !(IPCB(skb)->flags & IPSKB_FORWARDED))
324 #endif
325 ) {
326 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
327 if (newskb)
328 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
329 net, sk, newskb, NULL, newskb->dev,
330 dev_loopback_xmit);
331 }
332
333 /* Multicasts with ttl 0 must not go beyond the host */
334
335 if (ip_hdr(skb)->ttl == 0) {
336 kfree_skb(skb);
337 return 0;
338 }
339 }
340
341 if (rt->rt_flags&RTCF_BROADCAST) {
342 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
343 if (newskb)
344 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
345 net, sk, newskb, NULL, newskb->dev,
346 dev_loopback_xmit);
347 }
348
349 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
350 net, sk, skb, NULL, skb->dev,
351 ip_finish_output,
352 !(IPCB(skb)->flags & IPSKB_REROUTED));
353 }
354
355 int ip_output(struct sock *sk, struct sk_buff *skb)
356 {
357 struct net_device *dev = skb_dst(skb)->dev;
358 struct net *net = dev_net(dev);
359
360 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUT, skb->len);
361
362 skb->dev = dev;
363 skb->protocol = htons(ETH_P_IP);
364
365 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
366 net, sk, skb, NULL, dev,
367 ip_finish_output,
368 !(IPCB(skb)->flags & IPSKB_REROUTED));
369 }
370
371 /*
372 * copy saddr and daddr, possibly using 64bit load/stores
373 * Equivalent to :
374 * iph->saddr = fl4->saddr;
375 * iph->daddr = fl4->daddr;
376 */
377 static void ip_copy_addrs(struct iphdr *iph, const struct flowi4 *fl4)
378 {
379 BUILD_BUG_ON(offsetof(typeof(*fl4), daddr) !=
380 offsetof(typeof(*fl4), saddr) + sizeof(fl4->saddr));
381 memcpy(&iph->saddr, &fl4->saddr,
382 sizeof(fl4->saddr) + sizeof(fl4->daddr));
383 }
384
385 /* Note: skb->sk can be different from sk, in case of tunnels */
386 int ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl)
387 {
388 struct inet_sock *inet = inet_sk(sk);
389 struct ip_options_rcu *inet_opt;
390 struct flowi4 *fl4;
391 struct rtable *rt;
392 struct iphdr *iph;
393 int res;
394
395 /* Skip all of this if the packet is already routed,
396 * f.e. by something like SCTP.
397 */
398 rcu_read_lock();
399 inet_opt = rcu_dereference(inet->inet_opt);
400 fl4 = &fl->u.ip4;
401 rt = skb_rtable(skb);
402 if (rt)
403 goto packet_routed;
404
405 /* Make sure we can route this packet. */
406 rt = (struct rtable *)__sk_dst_check(sk, 0);
407 if (!rt) {
408 __be32 daddr;
409
410 /* Use correct destination address if we have options. */
411 daddr = inet->inet_daddr;
412 if (inet_opt && inet_opt->opt.srr)
413 daddr = inet_opt->opt.faddr;
414
415 /* If this fails, retransmit mechanism of transport layer will
416 * keep trying until route appears or the connection times
417 * itself out.
418 */
419 rt = ip_route_output_ports(sock_net(sk), fl4, sk,
420 daddr, inet->inet_saddr,
421 inet->inet_dport,
422 inet->inet_sport,
423 sk->sk_protocol,
424 RT_CONN_FLAGS(sk),
425 sk->sk_bound_dev_if);
426 if (IS_ERR(rt))
427 goto no_route;
428 sk_setup_caps(sk, &rt->dst);
429 }
430 skb_dst_set_noref(skb, &rt->dst);
431
432 packet_routed:
433 if (inet_opt && inet_opt->opt.is_strictroute && rt->rt_uses_gateway)
434 goto no_route;
435
436 /* OK, we know where to send it, allocate and build IP header. */
437 skb_push(skb, sizeof(struct iphdr) + (inet_opt ? inet_opt->opt.optlen : 0));
438 skb_reset_network_header(skb);
439 iph = ip_hdr(skb);
440 *((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (inet->tos & 0xff));
441 if (ip_dont_fragment(sk, &rt->dst) && !skb->ignore_df)
442 iph->frag_off = htons(IP_DF);
443 else
444 iph->frag_off = 0;
445 iph->ttl = ip_select_ttl(inet, &rt->dst);
446 iph->protocol = sk->sk_protocol;
447 ip_copy_addrs(iph, fl4);
448
449 /* Transport layer set skb->h.foo itself. */
450
451 if (inet_opt && inet_opt->opt.optlen) {
452 iph->ihl += inet_opt->opt.optlen >> 2;
453 ip_options_build(skb, &inet_opt->opt, inet->inet_daddr, rt, 0);
454 }
455
456 ip_select_ident_segs(sock_net(sk), skb, sk,
457 skb_shinfo(skb)->gso_segs ?: 1);
458
459 /* TODO : should we use skb->sk here instead of sk ? */
460 skb->priority = sk->sk_priority;
461 skb->mark = sk->sk_mark;
462
463 res = ip_local_out(skb);
464 rcu_read_unlock();
465 return res;
466
467 no_route:
468 rcu_read_unlock();
469 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
470 kfree_skb(skb);
471 return -EHOSTUNREACH;
472 }
473 EXPORT_SYMBOL(ip_queue_xmit);
474
475 static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from)
476 {
477 to->pkt_type = from->pkt_type;
478 to->priority = from->priority;
479 to->protocol = from->protocol;
480 skb_dst_drop(to);
481 skb_dst_copy(to, from);
482 to->dev = from->dev;
483 to->mark = from->mark;
484
485 /* Copy the flags to each fragment. */
486 IPCB(to)->flags = IPCB(from)->flags;
487
488 #ifdef CONFIG_NET_SCHED
489 to->tc_index = from->tc_index;
490 #endif
491 nf_copy(to, from);
492 #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
493 to->ipvs_property = from->ipvs_property;
494 #endif
495 skb_copy_secmark(to, from);
496 }
497
498 static int ip_fragment(struct sock *sk, struct sk_buff *skb,
499 unsigned int mtu,
500 int (*output)(struct sock *, struct sk_buff *))
501 {
502 struct iphdr *iph = ip_hdr(skb);
503
504 if ((iph->frag_off & htons(IP_DF)) == 0)
505 return ip_do_fragment(sk, skb, output);
506
507 if (unlikely(!skb->ignore_df ||
508 (IPCB(skb)->frag_max_size &&
509 IPCB(skb)->frag_max_size > mtu))) {
510 struct net *net = dev_net(skb_rtable(skb)->dst.dev);
511
512 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
513 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
514 htonl(mtu));
515 kfree_skb(skb);
516 return -EMSGSIZE;
517 }
518
519 return ip_do_fragment(sk, skb, output);
520 }
521
522 /*
523 * This IP datagram is too large to be sent in one piece. Break it up into
524 * smaller pieces (each of size equal to IP header plus
525 * a block of the data of the original IP data part) that will yet fit in a
526 * single device frame, and queue such a frame for sending.
527 */
528
529 int ip_do_fragment(struct sock *sk, struct sk_buff *skb,
530 int (*output)(struct sock *, struct sk_buff *))
531 {
532 struct iphdr *iph;
533 int ptr;
534 struct net_device *dev;
535 struct sk_buff *skb2;
536 unsigned int mtu, hlen, left, len, ll_rs;
537 int offset;
538 __be16 not_last_frag;
539 struct rtable *rt = skb_rtable(skb);
540 struct net *net;
541 int err = 0;
542
543 dev = rt->dst.dev;
544 net = dev_net(dev);
545
546 /*
547 * Point into the IP datagram header.
548 */
549
550 iph = ip_hdr(skb);
551
552 mtu = ip_skb_dst_mtu(skb);
553 if (IPCB(skb)->frag_max_size && IPCB(skb)->frag_max_size < mtu)
554 mtu = IPCB(skb)->frag_max_size;
555
556 /*
557 * Setup starting values.
558 */
559
560 hlen = iph->ihl * 4;
561 mtu = mtu - hlen; /* Size of data space */
562 IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE;
563
564 /* When frag_list is given, use it. First, check its validity:
565 * some transformers could create wrong frag_list or break existing
566 * one, it is not prohibited. In this case fall back to copying.
567 *
568 * LATER: this step can be merged to real generation of fragments,
569 * we can switch to copy when see the first bad fragment.
570 */
571 if (skb_has_frag_list(skb)) {
572 struct sk_buff *frag, *frag2;
573 int first_len = skb_pagelen(skb);
574
575 if (first_len - hlen > mtu ||
576 ((first_len - hlen) & 7) ||
577 ip_is_fragment(iph) ||
578 skb_cloned(skb))
579 goto slow_path;
580
581 skb_walk_frags(skb, frag) {
582 /* Correct geometry. */
583 if (frag->len > mtu ||
584 ((frag->len & 7) && frag->next) ||
585 skb_headroom(frag) < hlen)
586 goto slow_path_clean;
587
588 /* Partially cloned skb? */
589 if (skb_shared(frag))
590 goto slow_path_clean;
591
592 BUG_ON(frag->sk);
593 if (skb->sk) {
594 frag->sk = skb->sk;
595 frag->destructor = sock_wfree;
596 }
597 skb->truesize -= frag->truesize;
598 }
599
600 /* Everything is OK. Generate! */
601
602 err = 0;
603 offset = 0;
604 frag = skb_shinfo(skb)->frag_list;
605 skb_frag_list_init(skb);
606 skb->data_len = first_len - skb_headlen(skb);
607 skb->len = first_len;
608 iph->tot_len = htons(first_len);
609 iph->frag_off = htons(IP_MF);
610 ip_send_check(iph);
611
612 for (;;) {
613 /* Prepare header of the next frame,
614 * before previous one went down. */
615 if (frag) {
616 frag->ip_summed = CHECKSUM_NONE;
617 skb_reset_transport_header(frag);
618 __skb_push(frag, hlen);
619 skb_reset_network_header(frag);
620 memcpy(skb_network_header(frag), iph, hlen);
621 iph = ip_hdr(frag);
622 iph->tot_len = htons(frag->len);
623 ip_copy_metadata(frag, skb);
624 if (offset == 0)
625 ip_options_fragment(frag);
626 offset += skb->len - hlen;
627 iph->frag_off = htons(offset>>3);
628 if (frag->next)
629 iph->frag_off |= htons(IP_MF);
630 /* Ready, complete checksum */
631 ip_send_check(iph);
632 }
633
634 err = output(sk, skb);
635
636 if (!err)
637 IP_INC_STATS(net, IPSTATS_MIB_FRAGCREATES);
638 if (err || !frag)
639 break;
640
641 skb = frag;
642 frag = skb->next;
643 skb->next = NULL;
644 }
645
646 if (err == 0) {
647 IP_INC_STATS(net, IPSTATS_MIB_FRAGOKS);
648 return 0;
649 }
650
651 while (frag) {
652 skb = frag->next;
653 kfree_skb(frag);
654 frag = skb;
655 }
656 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
657 return err;
658
659 slow_path_clean:
660 skb_walk_frags(skb, frag2) {
661 if (frag2 == frag)
662 break;
663 frag2->sk = NULL;
664 frag2->destructor = NULL;
665 skb->truesize += frag2->truesize;
666 }
667 }
668
669 slow_path:
670 /* for offloaded checksums cleanup checksum before fragmentation */
671 if ((skb->ip_summed == CHECKSUM_PARTIAL) && skb_checksum_help(skb))
672 goto fail;
673 iph = ip_hdr(skb);
674
675 left = skb->len - hlen; /* Space per frame */
676 ptr = hlen; /* Where to start from */
677
678 ll_rs = LL_RESERVED_SPACE(rt->dst.dev);
679
680 /*
681 * Fragment the datagram.
682 */
683
684 offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3;
685 not_last_frag = iph->frag_off & htons(IP_MF);
686
687 /*
688 * Keep copying data until we run out.
689 */
690
691 while (left > 0) {
692 len = left;
693 /* IF: it doesn't fit, use 'mtu' - the data space left */
694 if (len > mtu)
695 len = mtu;
696 /* IF: we are not sending up to and including the packet end
697 then align the next start on an eight byte boundary */
698 if (len < left) {
699 len &= ~7;
700 }
701
702 /* Allocate buffer */
703 skb2 = alloc_skb(len + hlen + ll_rs, GFP_ATOMIC);
704 if (!skb2) {
705 err = -ENOMEM;
706 goto fail;
707 }
708
709 /*
710 * Set up data on packet
711 */
712
713 ip_copy_metadata(skb2, skb);
714 skb_reserve(skb2, ll_rs);
715 skb_put(skb2, len + hlen);
716 skb_reset_network_header(skb2);
717 skb2->transport_header = skb2->network_header + hlen;
718
719 /*
720 * Charge the memory for the fragment to any owner
721 * it might possess
722 */
723
724 if (skb->sk)
725 skb_set_owner_w(skb2, skb->sk);
726
727 /*
728 * Copy the packet header into the new buffer.
729 */
730
731 skb_copy_from_linear_data(skb, skb_network_header(skb2), hlen);
732
733 /*
734 * Copy a block of the IP datagram.
735 */
736 if (skb_copy_bits(skb, ptr, skb_transport_header(skb2), len))
737 BUG();
738 left -= len;
739
740 /*
741 * Fill in the new header fields.
742 */
743 iph = ip_hdr(skb2);
744 iph->frag_off = htons((offset >> 3));
745
746 if (IPCB(skb)->flags & IPSKB_FRAG_PMTU)
747 iph->frag_off |= htons(IP_DF);
748
749 /* ANK: dirty, but effective trick. Upgrade options only if
750 * the segment to be fragmented was THE FIRST (otherwise,
751 * options are already fixed) and make it ONCE
752 * on the initial skb, so that all the following fragments
753 * will inherit fixed options.
754 */
755 if (offset == 0)
756 ip_options_fragment(skb);
757
758 /*
759 * Added AC : If we are fragmenting a fragment that's not the
760 * last fragment then keep MF on each bit
761 */
762 if (left > 0 || not_last_frag)
763 iph->frag_off |= htons(IP_MF);
764 ptr += len;
765 offset += len;
766
767 /*
768 * Put this fragment into the sending queue.
769 */
770 iph->tot_len = htons(len + hlen);
771
772 ip_send_check(iph);
773
774 err = output(sk, skb2);
775 if (err)
776 goto fail;
777
778 IP_INC_STATS(net, IPSTATS_MIB_FRAGCREATES);
779 }
780 consume_skb(skb);
781 IP_INC_STATS(net, IPSTATS_MIB_FRAGOKS);
782 return err;
783
784 fail:
785 kfree_skb(skb);
786 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
787 return err;
788 }
789 EXPORT_SYMBOL(ip_do_fragment);
790
791 int
792 ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
793 {
794 struct msghdr *msg = from;
795
796 if (skb->ip_summed == CHECKSUM_PARTIAL) {
797 if (copy_from_iter(to, len, &msg->msg_iter) != len)
798 return -EFAULT;
799 } else {
800 __wsum csum = 0;
801 if (csum_and_copy_from_iter(to, len, &csum, &msg->msg_iter) != len)
802 return -EFAULT;
803 skb->csum = csum_block_add(skb->csum, csum, odd);
804 }
805 return 0;
806 }
807 EXPORT_SYMBOL(ip_generic_getfrag);
808
809 static inline __wsum
810 csum_page(struct page *page, int offset, int copy)
811 {
812 char *kaddr;
813 __wsum csum;
814 kaddr = kmap(page);
815 csum = csum_partial(kaddr + offset, copy, 0);
816 kunmap(page);
817 return csum;
818 }
819
820 static inline int ip_ufo_append_data(struct sock *sk,
821 struct sk_buff_head *queue,
822 int getfrag(void *from, char *to, int offset, int len,
823 int odd, struct sk_buff *skb),
824 void *from, int length, int hh_len, int fragheaderlen,
825 int transhdrlen, int maxfraglen, unsigned int flags)
826 {
827 struct sk_buff *skb;
828 int err;
829
830 /* There is support for UDP fragmentation offload by network
831 * device, so create one single skb packet containing complete
832 * udp datagram
833 */
834 skb = skb_peek_tail(queue);
835 if (!skb) {
836 skb = sock_alloc_send_skb(sk,
837 hh_len + fragheaderlen + transhdrlen + 20,
838 (flags & MSG_DONTWAIT), &err);
839
840 if (!skb)
841 return err;
842
843 /* reserve space for Hardware header */
844 skb_reserve(skb, hh_len);
845
846 /* create space for UDP/IP header */
847 skb_put(skb, fragheaderlen + transhdrlen);
848
849 /* initialize network header pointer */
850 skb_reset_network_header(skb);
851
852 /* initialize protocol header pointer */
853 skb->transport_header = skb->network_header + fragheaderlen;
854
855 skb->csum = 0;
856
857 __skb_queue_tail(queue, skb);
858 } else if (skb_is_gso(skb)) {
859 goto append;
860 }
861
862 skb->ip_summed = CHECKSUM_PARTIAL;
863 /* specify the length of each IP datagram fragment */
864 skb_shinfo(skb)->gso_size = maxfraglen - fragheaderlen;
865 skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
866
867 append:
868 return skb_append_datato_frags(sk, skb, getfrag, from,
869 (length - transhdrlen));
870 }
871
872 static int __ip_append_data(struct sock *sk,
873 struct flowi4 *fl4,
874 struct sk_buff_head *queue,
875 struct inet_cork *cork,
876 struct page_frag *pfrag,
877 int getfrag(void *from, char *to, int offset,
878 int len, int odd, struct sk_buff *skb),
879 void *from, int length, int transhdrlen,
880 unsigned int flags)
881 {
882 struct inet_sock *inet = inet_sk(sk);
883 struct sk_buff *skb;
884
885 struct ip_options *opt = cork->opt;
886 int hh_len;
887 int exthdrlen;
888 int mtu;
889 int copy;
890 int err;
891 int offset = 0;
892 unsigned int maxfraglen, fragheaderlen, maxnonfragsize;
893 int csummode = CHECKSUM_NONE;
894 struct rtable *rt = (struct rtable *)cork->dst;
895 u32 tskey = 0;
896
897 skb = skb_peek_tail(queue);
898
899 exthdrlen = !skb ? rt->dst.header_len : 0;
900 mtu = cork->fragsize;
901 if (cork->tx_flags & SKBTX_ANY_SW_TSTAMP &&
902 sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID)
903 tskey = sk->sk_tskey++;
904
905 hh_len = LL_RESERVED_SPACE(rt->dst.dev);
906
907 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
908 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
909 maxnonfragsize = ip_sk_ignore_df(sk) ? 0xFFFF : mtu;
910
911 if (cork->length + length > maxnonfragsize - fragheaderlen) {
912 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
913 mtu - (opt ? opt->optlen : 0));
914 return -EMSGSIZE;
915 }
916
917 /*
918 * transhdrlen > 0 means that this is the first fragment and we wish
919 * it won't be fragmented in the future.
920 */
921 if (transhdrlen &&
922 length + fragheaderlen <= mtu &&
923 rt->dst.dev->features & NETIF_F_V4_CSUM &&
924 !exthdrlen)
925 csummode = CHECKSUM_PARTIAL;
926
927 cork->length += length;
928 if (((length > mtu) || (skb && skb_is_gso(skb))) &&
929 (sk->sk_protocol == IPPROTO_UDP) &&
930 (rt->dst.dev->features & NETIF_F_UFO) && !rt->dst.header_len &&
931 (sk->sk_type == SOCK_DGRAM)) {
932 err = ip_ufo_append_data(sk, queue, getfrag, from, length,
933 hh_len, fragheaderlen, transhdrlen,
934 maxfraglen, flags);
935 if (err)
936 goto error;
937 return 0;
938 }
939
940 /* So, what's going on in the loop below?
941 *
942 * We use calculated fragment length to generate chained skb,
943 * each of segments is IP fragment ready for sending to network after
944 * adding appropriate IP header.
945 */
946
947 if (!skb)
948 goto alloc_new_skb;
949
950 while (length > 0) {
951 /* Check if the remaining data fits into current packet. */
952 copy = mtu - skb->len;
953 if (copy < length)
954 copy = maxfraglen - skb->len;
955 if (copy <= 0) {
956 char *data;
957 unsigned int datalen;
958 unsigned int fraglen;
959 unsigned int fraggap;
960 unsigned int alloclen;
961 struct sk_buff *skb_prev;
962 alloc_new_skb:
963 skb_prev = skb;
964 if (skb_prev)
965 fraggap = skb_prev->len - maxfraglen;
966 else
967 fraggap = 0;
968
969 /*
970 * If remaining data exceeds the mtu,
971 * we know we need more fragment(s).
972 */
973 datalen = length + fraggap;
974 if (datalen > mtu - fragheaderlen)
975 datalen = maxfraglen - fragheaderlen;
976 fraglen = datalen + fragheaderlen;
977
978 if ((flags & MSG_MORE) &&
979 !(rt->dst.dev->features&NETIF_F_SG))
980 alloclen = mtu;
981 else
982 alloclen = fraglen;
983
984 alloclen += exthdrlen;
985
986 /* The last fragment gets additional space at tail.
987 * Note, with MSG_MORE we overallocate on fragments,
988 * because we have no idea what fragment will be
989 * the last.
990 */
991 if (datalen == length + fraggap)
992 alloclen += rt->dst.trailer_len;
993
994 if (transhdrlen) {
995 skb = sock_alloc_send_skb(sk,
996 alloclen + hh_len + 15,
997 (flags & MSG_DONTWAIT), &err);
998 } else {
999 skb = NULL;
1000 if (atomic_read(&sk->sk_wmem_alloc) <=
1001 2 * sk->sk_sndbuf)
1002 skb = sock_wmalloc(sk,
1003 alloclen + hh_len + 15, 1,
1004 sk->sk_allocation);
1005 if (unlikely(!skb))
1006 err = -ENOBUFS;
1007 }
1008 if (!skb)
1009 goto error;
1010
1011 /*
1012 * Fill in the control structures
1013 */
1014 skb->ip_summed = csummode;
1015 skb->csum = 0;
1016 skb_reserve(skb, hh_len);
1017
1018 /* only the initial fragment is time stamped */
1019 skb_shinfo(skb)->tx_flags = cork->tx_flags;
1020 cork->tx_flags = 0;
1021 skb_shinfo(skb)->tskey = tskey;
1022 tskey = 0;
1023
1024 /*
1025 * Find where to start putting bytes.
1026 */
1027 data = skb_put(skb, fraglen + exthdrlen);
1028 skb_set_network_header(skb, exthdrlen);
1029 skb->transport_header = (skb->network_header +
1030 fragheaderlen);
1031 data += fragheaderlen + exthdrlen;
1032
1033 if (fraggap) {
1034 skb->csum = skb_copy_and_csum_bits(
1035 skb_prev, maxfraglen,
1036 data + transhdrlen, fraggap, 0);
1037 skb_prev->csum = csum_sub(skb_prev->csum,
1038 skb->csum);
1039 data += fraggap;
1040 pskb_trim_unique(skb_prev, maxfraglen);
1041 }
1042
1043 copy = datalen - transhdrlen - fraggap;
1044 if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) {
1045 err = -EFAULT;
1046 kfree_skb(skb);
1047 goto error;
1048 }
1049
1050 offset += copy;
1051 length -= datalen - fraggap;
1052 transhdrlen = 0;
1053 exthdrlen = 0;
1054 csummode = CHECKSUM_NONE;
1055
1056 /*
1057 * Put the packet on the pending queue.
1058 */
1059 __skb_queue_tail(queue, skb);
1060 continue;
1061 }
1062
1063 if (copy > length)
1064 copy = length;
1065
1066 if (!(rt->dst.dev->features&NETIF_F_SG)) {
1067 unsigned int off;
1068
1069 off = skb->len;
1070 if (getfrag(from, skb_put(skb, copy),
1071 offset, copy, off, skb) < 0) {
1072 __skb_trim(skb, off);
1073 err = -EFAULT;
1074 goto error;
1075 }
1076 } else {
1077 int i = skb_shinfo(skb)->nr_frags;
1078
1079 err = -ENOMEM;
1080 if (!sk_page_frag_refill(sk, pfrag))
1081 goto error;
1082
1083 if (!skb_can_coalesce(skb, i, pfrag->page,
1084 pfrag->offset)) {
1085 err = -EMSGSIZE;
1086 if (i == MAX_SKB_FRAGS)
1087 goto error;
1088
1089 __skb_fill_page_desc(skb, i, pfrag->page,
1090 pfrag->offset, 0);
1091 skb_shinfo(skb)->nr_frags = ++i;
1092 get_page(pfrag->page);
1093 }
1094 copy = min_t(int, copy, pfrag->size - pfrag->offset);
1095 if (getfrag(from,
1096 page_address(pfrag->page) + pfrag->offset,
1097 offset, copy, skb->len, skb) < 0)
1098 goto error_efault;
1099
1100 pfrag->offset += copy;
1101 skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
1102 skb->len += copy;
1103 skb->data_len += copy;
1104 skb->truesize += copy;
1105 atomic_add(copy, &sk->sk_wmem_alloc);
1106 }
1107 offset += copy;
1108 length -= copy;
1109 }
1110
1111 return 0;
1112
1113 error_efault:
1114 err = -EFAULT;
1115 error:
1116 cork->length -= length;
1117 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1118 return err;
1119 }
1120
1121 static int ip_setup_cork(struct sock *sk, struct inet_cork *cork,
1122 struct ipcm_cookie *ipc, struct rtable **rtp)
1123 {
1124 struct ip_options_rcu *opt;
1125 struct rtable *rt;
1126
1127 /*
1128 * setup for corking.
1129 */
1130 opt = ipc->opt;
1131 if (opt) {
1132 if (!cork->opt) {
1133 cork->opt = kmalloc(sizeof(struct ip_options) + 40,
1134 sk->sk_allocation);
1135 if (unlikely(!cork->opt))
1136 return -ENOBUFS;
1137 }
1138 memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen);
1139 cork->flags |= IPCORK_OPT;
1140 cork->addr = ipc->addr;
1141 }
1142 rt = *rtp;
1143 if (unlikely(!rt))
1144 return -EFAULT;
1145 /*
1146 * We steal reference to this route, caller should not release it
1147 */
1148 *rtp = NULL;
1149 cork->fragsize = ip_sk_use_pmtu(sk) ?
1150 dst_mtu(&rt->dst) : rt->dst.dev->mtu;
1151 cork->dst = &rt->dst;
1152 cork->length = 0;
1153 cork->ttl = ipc->ttl;
1154 cork->tos = ipc->tos;
1155 cork->priority = ipc->priority;
1156 cork->tx_flags = ipc->tx_flags;
1157
1158 return 0;
1159 }
1160
1161 /*
1162 * ip_append_data() and ip_append_page() can make one large IP datagram
1163 * from many pieces of data. Each pieces will be holded on the socket
1164 * until ip_push_pending_frames() is called. Each piece can be a page
1165 * or non-page data.
1166 *
1167 * Not only UDP, other transport protocols - e.g. raw sockets - can use
1168 * this interface potentially.
1169 *
1170 * LATER: length must be adjusted by pad at tail, when it is required.
1171 */
1172 int ip_append_data(struct sock *sk, struct flowi4 *fl4,
1173 int getfrag(void *from, char *to, int offset, int len,
1174 int odd, struct sk_buff *skb),
1175 void *from, int length, int transhdrlen,
1176 struct ipcm_cookie *ipc, struct rtable **rtp,
1177 unsigned int flags)
1178 {
1179 struct inet_sock *inet = inet_sk(sk);
1180 int err;
1181
1182 if (flags&MSG_PROBE)
1183 return 0;
1184
1185 if (skb_queue_empty(&sk->sk_write_queue)) {
1186 err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp);
1187 if (err)
1188 return err;
1189 } else {
1190 transhdrlen = 0;
1191 }
1192
1193 return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base,
1194 sk_page_frag(sk), getfrag,
1195 from, length, transhdrlen, flags);
1196 }
1197
1198 ssize_t ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page,
1199 int offset, size_t size, int flags)
1200 {
1201 struct inet_sock *inet = inet_sk(sk);
1202 struct sk_buff *skb;
1203 struct rtable *rt;
1204 struct ip_options *opt = NULL;
1205 struct inet_cork *cork;
1206 int hh_len;
1207 int mtu;
1208 int len;
1209 int err;
1210 unsigned int maxfraglen, fragheaderlen, fraggap, maxnonfragsize;
1211
1212 if (inet->hdrincl)
1213 return -EPERM;
1214
1215 if (flags&MSG_PROBE)
1216 return 0;
1217
1218 if (skb_queue_empty(&sk->sk_write_queue))
1219 return -EINVAL;
1220
1221 cork = &inet->cork.base;
1222 rt = (struct rtable *)cork->dst;
1223 if (cork->flags & IPCORK_OPT)
1224 opt = cork->opt;
1225
1226 if (!(rt->dst.dev->features&NETIF_F_SG))
1227 return -EOPNOTSUPP;
1228
1229 hh_len = LL_RESERVED_SPACE(rt->dst.dev);
1230 mtu = cork->fragsize;
1231
1232 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
1233 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
1234 maxnonfragsize = ip_sk_ignore_df(sk) ? 0xFFFF : mtu;
1235
1236 if (cork->length + size > maxnonfragsize - fragheaderlen) {
1237 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
1238 mtu - (opt ? opt->optlen : 0));
1239 return -EMSGSIZE;
1240 }
1241
1242 skb = skb_peek_tail(&sk->sk_write_queue);
1243 if (!skb)
1244 return -EINVAL;
1245
1246 cork->length += size;
1247 if ((size + skb->len > mtu) &&
1248 (sk->sk_protocol == IPPROTO_UDP) &&
1249 (rt->dst.dev->features & NETIF_F_UFO)) {
1250 skb_shinfo(skb)->gso_size = mtu - fragheaderlen;
1251 skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
1252 }
1253
1254 while (size > 0) {
1255 if (skb_is_gso(skb)) {
1256 len = size;
1257 } else {
1258
1259 /* Check if the remaining data fits into current packet. */
1260 len = mtu - skb->len;
1261 if (len < size)
1262 len = maxfraglen - skb->len;
1263 }
1264 if (len <= 0) {
1265 struct sk_buff *skb_prev;
1266 int alloclen;
1267
1268 skb_prev = skb;
1269 fraggap = skb_prev->len - maxfraglen;
1270
1271 alloclen = fragheaderlen + hh_len + fraggap + 15;
1272 skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation);
1273 if (unlikely(!skb)) {
1274 err = -ENOBUFS;
1275 goto error;
1276 }
1277
1278 /*
1279 * Fill in the control structures
1280 */
1281 skb->ip_summed = CHECKSUM_NONE;
1282 skb->csum = 0;
1283 skb_reserve(skb, hh_len);
1284
1285 /*
1286 * Find where to start putting bytes.
1287 */
1288 skb_put(skb, fragheaderlen + fraggap);
1289 skb_reset_network_header(skb);
1290 skb->transport_header = (skb->network_header +
1291 fragheaderlen);
1292 if (fraggap) {
1293 skb->csum = skb_copy_and_csum_bits(skb_prev,
1294 maxfraglen,
1295 skb_transport_header(skb),
1296 fraggap, 0);
1297 skb_prev->csum = csum_sub(skb_prev->csum,
1298 skb->csum);
1299 pskb_trim_unique(skb_prev, maxfraglen);
1300 }
1301
1302 /*
1303 * Put the packet on the pending queue.
1304 */
1305 __skb_queue_tail(&sk->sk_write_queue, skb);
1306 continue;
1307 }
1308
1309 if (len > size)
1310 len = size;
1311
1312 if (skb_append_pagefrags(skb, page, offset, len)) {
1313 err = -EMSGSIZE;
1314 goto error;
1315 }
1316
1317 if (skb->ip_summed == CHECKSUM_NONE) {
1318 __wsum csum;
1319 csum = csum_page(page, offset, len);
1320 skb->csum = csum_block_add(skb->csum, csum, skb->len);
1321 }
1322
1323 skb->len += len;
1324 skb->data_len += len;
1325 skb->truesize += len;
1326 atomic_add(len, &sk->sk_wmem_alloc);
1327 offset += len;
1328 size -= len;
1329 }
1330 return 0;
1331
1332 error:
1333 cork->length -= size;
1334 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1335 return err;
1336 }
1337
1338 static void ip_cork_release(struct inet_cork *cork)
1339 {
1340 cork->flags &= ~IPCORK_OPT;
1341 kfree(cork->opt);
1342 cork->opt = NULL;
1343 dst_release(cork->dst);
1344 cork->dst = NULL;
1345 }
1346
1347 /*
1348 * Combined all pending IP fragments on the socket as one IP datagram
1349 * and push them out.
1350 */
1351 struct sk_buff *__ip_make_skb(struct sock *sk,
1352 struct flowi4 *fl4,
1353 struct sk_buff_head *queue,
1354 struct inet_cork *cork)
1355 {
1356 struct sk_buff *skb, *tmp_skb;
1357 struct sk_buff **tail_skb;
1358 struct inet_sock *inet = inet_sk(sk);
1359 struct net *net = sock_net(sk);
1360 struct ip_options *opt = NULL;
1361 struct rtable *rt = (struct rtable *)cork->dst;
1362 struct iphdr *iph;
1363 __be16 df = 0;
1364 __u8 ttl;
1365
1366 skb = __skb_dequeue(queue);
1367 if (!skb)
1368 goto out;
1369 tail_skb = &(skb_shinfo(skb)->frag_list);
1370
1371 /* move skb->data to ip header from ext header */
1372 if (skb->data < skb_network_header(skb))
1373 __skb_pull(skb, skb_network_offset(skb));
1374 while ((tmp_skb = __skb_dequeue(queue)) != NULL) {
1375 __skb_pull(tmp_skb, skb_network_header_len(skb));
1376 *tail_skb = tmp_skb;
1377 tail_skb = &(tmp_skb->next);
1378 skb->len += tmp_skb->len;
1379 skb->data_len += tmp_skb->len;
1380 skb->truesize += tmp_skb->truesize;
1381 tmp_skb->destructor = NULL;
1382 tmp_skb->sk = NULL;
1383 }
1384
1385 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow
1386 * to fragment the frame generated here. No matter, what transforms
1387 * how transforms change size of the packet, it will come out.
1388 */
1389 skb->ignore_df = ip_sk_ignore_df(sk);
1390
1391 /* DF bit is set when we want to see DF on outgoing frames.
1392 * If ignore_df is set too, we still allow to fragment this frame
1393 * locally. */
1394 if (inet->pmtudisc == IP_PMTUDISC_DO ||
1395 inet->pmtudisc == IP_PMTUDISC_PROBE ||
1396 (skb->len <= dst_mtu(&rt->dst) &&
1397 ip_dont_fragment(sk, &rt->dst)))
1398 df = htons(IP_DF);
1399
1400 if (cork->flags & IPCORK_OPT)
1401 opt = cork->opt;
1402
1403 if (cork->ttl != 0)
1404 ttl = cork->ttl;
1405 else if (rt->rt_type == RTN_MULTICAST)
1406 ttl = inet->mc_ttl;
1407 else
1408 ttl = ip_select_ttl(inet, &rt->dst);
1409
1410 iph = ip_hdr(skb);
1411 iph->version = 4;
1412 iph->ihl = 5;
1413 iph->tos = (cork->tos != -1) ? cork->tos : inet->tos;
1414 iph->frag_off = df;
1415 iph->ttl = ttl;
1416 iph->protocol = sk->sk_protocol;
1417 ip_copy_addrs(iph, fl4);
1418 ip_select_ident(net, skb, sk);
1419
1420 if (opt) {
1421 iph->ihl += opt->optlen>>2;
1422 ip_options_build(skb, opt, cork->addr, rt, 0);
1423 }
1424
1425 skb->priority = (cork->tos != -1) ? cork->priority: sk->sk_priority;
1426 skb->mark = sk->sk_mark;
1427 /*
1428 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec
1429 * on dst refcount
1430 */
1431 cork->dst = NULL;
1432 skb_dst_set(skb, &rt->dst);
1433
1434 if (iph->protocol == IPPROTO_ICMP)
1435 icmp_out_count(net, ((struct icmphdr *)
1436 skb_transport_header(skb))->type);
1437
1438 ip_cork_release(cork);
1439 out:
1440 return skb;
1441 }
1442
1443 int ip_send_skb(struct net *net, struct sk_buff *skb)
1444 {
1445 int err;
1446
1447 err = ip_local_out(skb);
1448 if (err) {
1449 if (err > 0)
1450 err = net_xmit_errno(err);
1451 if (err)
1452 IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS);
1453 }
1454
1455 return err;
1456 }
1457
1458 int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4)
1459 {
1460 struct sk_buff *skb;
1461
1462 skb = ip_finish_skb(sk, fl4);
1463 if (!skb)
1464 return 0;
1465
1466 /* Netfilter gets whole the not fragmented skb. */
1467 return ip_send_skb(sock_net(sk), skb);
1468 }
1469
1470 /*
1471 * Throw away all pending data on the socket.
1472 */
1473 static void __ip_flush_pending_frames(struct sock *sk,
1474 struct sk_buff_head *queue,
1475 struct inet_cork *cork)
1476 {
1477 struct sk_buff *skb;
1478
1479 while ((skb = __skb_dequeue_tail(queue)) != NULL)
1480 kfree_skb(skb);
1481
1482 ip_cork_release(cork);
1483 }
1484
1485 void ip_flush_pending_frames(struct sock *sk)
1486 {
1487 __ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork.base);
1488 }
1489
1490 struct sk_buff *ip_make_skb(struct sock *sk,
1491 struct flowi4 *fl4,
1492 int getfrag(void *from, char *to, int offset,
1493 int len, int odd, struct sk_buff *skb),
1494 void *from, int length, int transhdrlen,
1495 struct ipcm_cookie *ipc, struct rtable **rtp,
1496 unsigned int flags)
1497 {
1498 struct inet_cork cork;
1499 struct sk_buff_head queue;
1500 int err;
1501
1502 if (flags & MSG_PROBE)
1503 return NULL;
1504
1505 __skb_queue_head_init(&queue);
1506
1507 cork.flags = 0;
1508 cork.addr = 0;
1509 cork.opt = NULL;
1510 err = ip_setup_cork(sk, &cork, ipc, rtp);
1511 if (err)
1512 return ERR_PTR(err);
1513
1514 err = __ip_append_data(sk, fl4, &queue, &cork,
1515 &current->task_frag, getfrag,
1516 from, length, transhdrlen, flags);
1517 if (err) {
1518 __ip_flush_pending_frames(sk, &queue, &cork);
1519 return ERR_PTR(err);
1520 }
1521
1522 return __ip_make_skb(sk, fl4, &queue, &cork);
1523 }
1524
1525 /*
1526 * Fetch data from kernel space and fill in checksum if needed.
1527 */
1528 static int ip_reply_glue_bits(void *dptr, char *to, int offset,
1529 int len, int odd, struct sk_buff *skb)
1530 {
1531 __wsum csum;
1532
1533 csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0);
1534 skb->csum = csum_block_add(skb->csum, csum, odd);
1535 return 0;
1536 }
1537
1538 /*
1539 * Generic function to send a packet as reply to another packet.
1540 * Used to send some TCP resets/acks so far.
1541 */
1542 void ip_send_unicast_reply(struct sock *sk, struct sk_buff *skb,
1543 const struct ip_options *sopt,
1544 __be32 daddr, __be32 saddr,
1545 const struct ip_reply_arg *arg,
1546 unsigned int len)
1547 {
1548 struct ip_options_data replyopts;
1549 struct ipcm_cookie ipc;
1550 struct flowi4 fl4;
1551 struct rtable *rt = skb_rtable(skb);
1552 struct net *net = sock_net(sk);
1553 struct sk_buff *nskb;
1554 int err;
1555 int oif;
1556
1557 if (__ip_options_echo(&replyopts.opt.opt, skb, sopt))
1558 return;
1559
1560 ipc.addr = daddr;
1561 ipc.opt = NULL;
1562 ipc.tx_flags = 0;
1563 ipc.ttl = 0;
1564 ipc.tos = -1;
1565
1566 if (replyopts.opt.opt.optlen) {
1567 ipc.opt = &replyopts.opt;
1568
1569 if (replyopts.opt.opt.srr)
1570 daddr = replyopts.opt.opt.faddr;
1571 }
1572
1573 oif = arg->bound_dev_if;
1574 if (!oif && netif_index_is_vrf(net, skb->skb_iif))
1575 oif = skb->skb_iif;
1576
1577 flowi4_init_output(&fl4, oif,
1578 IP4_REPLY_MARK(net, skb->mark),
1579 RT_TOS(arg->tos),
1580 RT_SCOPE_UNIVERSE, ip_hdr(skb)->protocol,
1581 ip_reply_arg_flowi_flags(arg),
1582 daddr, saddr,
1583 tcp_hdr(skb)->source, tcp_hdr(skb)->dest);
1584 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
1585 rt = ip_route_output_key(net, &fl4);
1586 if (IS_ERR(rt))
1587 return;
1588
1589 inet_sk(sk)->tos = arg->tos;
1590
1591 sk->sk_priority = skb->priority;
1592 sk->sk_protocol = ip_hdr(skb)->protocol;
1593 sk->sk_bound_dev_if = arg->bound_dev_if;
1594 sk->sk_sndbuf = sysctl_wmem_default;
1595 err = ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base,
1596 len, 0, &ipc, &rt, MSG_DONTWAIT);
1597 if (unlikely(err)) {
1598 ip_flush_pending_frames(sk);
1599 goto out;
1600 }
1601
1602 nskb = skb_peek(&sk->sk_write_queue);
1603 if (nskb) {
1604 if (arg->csumoffset >= 0)
1605 *((__sum16 *)skb_transport_header(nskb) +
1606 arg->csumoffset) = csum_fold(csum_add(nskb->csum,
1607 arg->csum));
1608 nskb->ip_summed = CHECKSUM_NONE;
1609 skb_set_queue_mapping(nskb, skb_get_queue_mapping(skb));
1610 ip_push_pending_frames(sk, &fl4);
1611 }
1612 out:
1613 ip_rt_put(rt);
1614 }
1615
1616 void __init ip_init(void)
1617 {
1618 ip_rt_init();
1619 inet_initpeers();
1620
1621 #if defined(CONFIG_IP_MULTICAST)
1622 igmp_mc_init();
1623 #endif
1624 }
Linux kernel - Deliverables
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