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