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Btrfs: do error checking in btrfs_del_csums
[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 <asm/system.h>
47 #include <linux/module.h>
48 #include <linux/types.h>
49 #include <linux/kernel.h>
50 #include <linux/mm.h>
51 #include <linux/string.h>
52 #include <linux/errno.h>
53 #include <linux/highmem.h>
54 #include <linux/slab.h>
55
56 #include <linux/socket.h>
57 #include <linux/sockios.h>
58 #include <linux/in.h>
59 #include <linux/inet.h>
60 #include <linux/netdevice.h>
61 #include <linux/etherdevice.h>
62 #include <linux/proc_fs.h>
63 #include <linux/stat.h>
64 #include <linux/init.h>
65
66 #include <net/snmp.h>
67 #include <net/ip.h>
68 #include <net/protocol.h>
69 #include <net/route.h>
70 #include <net/xfrm.h>
71 #include <linux/skbuff.h>
72 #include <net/sock.h>
73 #include <net/arp.h>
74 #include <net/icmp.h>
75 #include <net/checksum.h>
76 #include <net/inetpeer.h>
77 #include <linux/igmp.h>
78 #include <linux/netfilter_ipv4.h>
79 #include <linux/netfilter_bridge.h>
80 #include <linux/mroute.h>
81 #include <linux/netlink.h>
82 #include <linux/tcp.h>
83
84 int sysctl_ip_default_ttl __read_mostly = IPDEFTTL;
85
86 /* Generate a checksum for an outgoing IP datagram. */
87 __inline__ 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(struct sk_buff *skb)
105 {
106 int err;
107
108 err = __ip_local_out(skb);
109 if (likely(err == 1))
110 err = dst_output(skb);
111
112 return err;
113 }
114 EXPORT_SYMBOL_GPL(ip_local_out);
115
116 /* dev_loopback_xmit for use with netfilter. */
117 static int ip_dev_loopback_xmit(struct sk_buff *newskb)
118 {
119 skb_reset_mac_header(newskb);
120 __skb_pull(newskb, skb_network_offset(newskb));
121 newskb->pkt_type = PACKET_LOOPBACK;
122 newskb->ip_summed = CHECKSUM_UNNECESSARY;
123 WARN_ON(!skb_dst(newskb));
124 netif_rx_ni(newskb);
125 return 0;
126 }
127
128 static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst)
129 {
130 int ttl = inet->uc_ttl;
131
132 if (ttl < 0)
133 ttl = dst_metric(dst, RTAX_HOPLIMIT);
134 return ttl;
135 }
136
137 /*
138 * Add an ip header to a skbuff and send it out.
139 *
140 */
141 int ip_build_and_send_pkt(struct sk_buff *skb, struct sock *sk,
142 __be32 saddr, __be32 daddr, struct ip_options *opt)
143 {
144 struct inet_sock *inet = inet_sk(sk);
145 struct rtable *rt = skb_rtable(skb);
146 struct iphdr *iph;
147
148 /* Build the IP header. */
149 skb_push(skb, sizeof(struct iphdr) + (opt ? opt->optlen : 0));
150 skb_reset_network_header(skb);
151 iph = ip_hdr(skb);
152 iph->version = 4;
153 iph->ihl = 5;
154 iph->tos = inet->tos;
155 if (ip_dont_fragment(sk, &rt->dst))
156 iph->frag_off = htons(IP_DF);
157 else
158 iph->frag_off = 0;
159 iph->ttl = ip_select_ttl(inet, &rt->dst);
160 iph->daddr = rt->rt_dst;
161 iph->saddr = rt->rt_src;
162 iph->protocol = sk->sk_protocol;
163 ip_select_ident(iph, &rt->dst, sk);
164
165 if (opt && opt->optlen) {
166 iph->ihl += opt->optlen>>2;
167 ip_options_build(skb, opt, daddr, rt, 0);
168 }
169
170 skb->priority = sk->sk_priority;
171 skb->mark = sk->sk_mark;
172
173 /* Send it out. */
174 return ip_local_out(skb);
175 }
176 EXPORT_SYMBOL_GPL(ip_build_and_send_pkt);
177
178 static inline int ip_finish_output2(struct sk_buff *skb)
179 {
180 struct dst_entry *dst = skb_dst(skb);
181 struct rtable *rt = (struct rtable *)dst;
182 struct net_device *dev = dst->dev;
183 unsigned int hh_len = LL_RESERVED_SPACE(dev);
184
185 if (rt->rt_type == RTN_MULTICAST) {
186 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUTMCAST, skb->len);
187 } else if (rt->rt_type == RTN_BROADCAST)
188 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUTBCAST, skb->len);
189
190 /* Be paranoid, rather than too clever. */
191 if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) {
192 struct sk_buff *skb2;
193
194 skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev));
195 if (skb2 == NULL) {
196 kfree_skb(skb);
197 return -ENOMEM;
198 }
199 if (skb->sk)
200 skb_set_owner_w(skb2, skb->sk);
201 kfree_skb(skb);
202 skb = skb2;
203 }
204
205 if (dst->hh)
206 return neigh_hh_output(dst->hh, skb);
207 else if (dst->neighbour)
208 return dst->neighbour->output(skb);
209
210 if (net_ratelimit())
211 printk(KERN_DEBUG "ip_finish_output2: No header cache and no neighbour!\n");
212 kfree_skb(skb);
213 return -EINVAL;
214 }
215
216 static inline int ip_skb_dst_mtu(struct sk_buff *skb)
217 {
218 struct inet_sock *inet = skb->sk ? inet_sk(skb->sk) : NULL;
219
220 return (inet && inet->pmtudisc == IP_PMTUDISC_PROBE) ?
221 skb_dst(skb)->dev->mtu : dst_mtu(skb_dst(skb));
222 }
223
224 static int ip_finish_output(struct sk_buff *skb)
225 {
226 #if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
227 /* Policy lookup after SNAT yielded a new policy */
228 if (skb_dst(skb)->xfrm != NULL) {
229 IPCB(skb)->flags |= IPSKB_REROUTED;
230 return dst_output(skb);
231 }
232 #endif
233 if (skb->len > ip_skb_dst_mtu(skb) && !skb_is_gso(skb))
234 return ip_fragment(skb, ip_finish_output2);
235 else
236 return ip_finish_output2(skb);
237 }
238
239 int ip_mc_output(struct sk_buff *skb)
240 {
241 struct sock *sk = skb->sk;
242 struct rtable *rt = skb_rtable(skb);
243 struct net_device *dev = rt->dst.dev;
244
245 /*
246 * If the indicated interface is up and running, send the packet.
247 */
248 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len);
249
250 skb->dev = dev;
251 skb->protocol = htons(ETH_P_IP);
252
253 /*
254 * Multicasts are looped back for other local users
255 */
256
257 if (rt->rt_flags&RTCF_MULTICAST) {
258 if (sk_mc_loop(sk)
259 #ifdef CONFIG_IP_MROUTE
260 /* Small optimization: do not loopback not local frames,
261 which returned after forwarding; they will be dropped
262 by ip_mr_input in any case.
263 Note, that local frames are looped back to be delivered
264 to local recipients.
265
266 This check is duplicated in ip_mr_input at the moment.
267 */
268 &&
269 ((rt->rt_flags & RTCF_LOCAL) ||
270 !(IPCB(skb)->flags & IPSKB_FORWARDED))
271 #endif
272 ) {
273 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
274 if (newskb)
275 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
276 newskb, NULL, newskb->dev,
277 ip_dev_loopback_xmit);
278 }
279
280 /* Multicasts with ttl 0 must not go beyond the host */
281
282 if (ip_hdr(skb)->ttl == 0) {
283 kfree_skb(skb);
284 return 0;
285 }
286 }
287
288 if (rt->rt_flags&RTCF_BROADCAST) {
289 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
290 if (newskb)
291 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, newskb,
292 NULL, newskb->dev, ip_dev_loopback_xmit);
293 }
294
295 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb, NULL,
296 skb->dev, ip_finish_output,
297 !(IPCB(skb)->flags & IPSKB_REROUTED));
298 }
299
300 int ip_output(struct sk_buff *skb)
301 {
302 struct net_device *dev = skb_dst(skb)->dev;
303
304 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len);
305
306 skb->dev = dev;
307 skb->protocol = htons(ETH_P_IP);
308
309 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb, NULL, dev,
310 ip_finish_output,
311 !(IPCB(skb)->flags & IPSKB_REROUTED));
312 }
313
314 int ip_queue_xmit(struct sk_buff *skb)
315 {
316 struct sock *sk = skb->sk;
317 struct inet_sock *inet = inet_sk(sk);
318 struct ip_options *opt = inet->opt;
319 struct rtable *rt;
320 struct iphdr *iph;
321 int res;
322
323 /* Skip all of this if the packet is already routed,
324 * f.e. by something like SCTP.
325 */
326 rcu_read_lock();
327 rt = skb_rtable(skb);
328 if (rt != NULL)
329 goto packet_routed;
330
331 /* Make sure we can route this packet. */
332 rt = (struct rtable *)__sk_dst_check(sk, 0);
333 if (rt == NULL) {
334 __be32 daddr;
335
336 /* Use correct destination address if we have options. */
337 daddr = inet->inet_daddr;
338 if(opt && opt->srr)
339 daddr = opt->faddr;
340
341 {
342 struct flowi fl = { .oif = sk->sk_bound_dev_if,
343 .mark = sk->sk_mark,
344 .nl_u = { .ip4_u =
345 { .daddr = daddr,
346 .saddr = inet->inet_saddr,
347 .tos = RT_CONN_FLAGS(sk) } },
348 .proto = sk->sk_protocol,
349 .flags = inet_sk_flowi_flags(sk),
350 .uli_u = { .ports =
351 { .sport = inet->inet_sport,
352 .dport = inet->inet_dport } } };
353
354 /* If this fails, retransmit mechanism of transport layer will
355 * keep trying until route appears or the connection times
356 * itself out.
357 */
358 security_sk_classify_flow(sk, &fl);
359 if (ip_route_output_flow(sock_net(sk), &rt, &fl, sk, 0))
360 goto no_route;
361 }
362 sk_setup_caps(sk, &rt->dst);
363 }
364 skb_dst_set_noref(skb, &rt->dst);
365
366 packet_routed:
367 if (opt && opt->is_strictroute && rt->rt_dst != rt->rt_gateway)
368 goto no_route;
369
370 /* OK, we know where to send it, allocate and build IP header. */
371 skb_push(skb, sizeof(struct iphdr) + (opt ? opt->optlen : 0));
372 skb_reset_network_header(skb);
373 iph = ip_hdr(skb);
374 *((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (inet->tos & 0xff));
375 if (ip_dont_fragment(sk, &rt->dst) && !skb->local_df)
376 iph->frag_off = htons(IP_DF);
377 else
378 iph->frag_off = 0;
379 iph->ttl = ip_select_ttl(inet, &rt->dst);
380 iph->protocol = sk->sk_protocol;
381 iph->saddr = rt->rt_src;
382 iph->daddr = rt->rt_dst;
383 /* Transport layer set skb->h.foo itself. */
384
385 if (opt && opt->optlen) {
386 iph->ihl += opt->optlen >> 2;
387 ip_options_build(skb, opt, inet->inet_daddr, rt, 0);
388 }
389
390 ip_select_ident_more(iph, &rt->dst, sk,
391 (skb_shinfo(skb)->gso_segs ?: 1) - 1);
392
393 skb->priority = sk->sk_priority;
394 skb->mark = sk->sk_mark;
395
396 res = ip_local_out(skb);
397 rcu_read_unlock();
398 return res;
399
400 no_route:
401 rcu_read_unlock();
402 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
403 kfree_skb(skb);
404 return -EHOSTUNREACH;
405 }
406 EXPORT_SYMBOL(ip_queue_xmit);
407
408
409 static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from)
410 {
411 to->pkt_type = from->pkt_type;
412 to->priority = from->priority;
413 to->protocol = from->protocol;
414 skb_dst_drop(to);
415 skb_dst_copy(to, from);
416 to->dev = from->dev;
417 to->mark = from->mark;
418
419 /* Copy the flags to each fragment. */
420 IPCB(to)->flags = IPCB(from)->flags;
421
422 #ifdef CONFIG_NET_SCHED
423 to->tc_index = from->tc_index;
424 #endif
425 nf_copy(to, from);
426 #if defined(CONFIG_NETFILTER_XT_TARGET_TRACE) || \
427 defined(CONFIG_NETFILTER_XT_TARGET_TRACE_MODULE)
428 to->nf_trace = from->nf_trace;
429 #endif
430 #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
431 to->ipvs_property = from->ipvs_property;
432 #endif
433 skb_copy_secmark(to, from);
434 }
435
436 /*
437 * This IP datagram is too large to be sent in one piece. Break it up into
438 * smaller pieces (each of size equal to IP header plus
439 * a block of the data of the original IP data part) that will yet fit in a
440 * single device frame, and queue such a frame for sending.
441 */
442
443 int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *))
444 {
445 struct iphdr *iph;
446 int ptr;
447 struct net_device *dev;
448 struct sk_buff *skb2;
449 unsigned int mtu, hlen, left, len, ll_rs;
450 int offset;
451 __be16 not_last_frag;
452 struct rtable *rt = skb_rtable(skb);
453 int err = 0;
454
455 dev = rt->dst.dev;
456
457 /*
458 * Point into the IP datagram header.
459 */
460
461 iph = ip_hdr(skb);
462
463 if (unlikely((iph->frag_off & htons(IP_DF)) && !skb->local_df)) {
464 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
465 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
466 htonl(ip_skb_dst_mtu(skb)));
467 kfree_skb(skb);
468 return -EMSGSIZE;
469 }
470
471 /*
472 * Setup starting values.
473 */
474
475 hlen = iph->ihl * 4;
476 mtu = dst_mtu(&rt->dst) - hlen; /* Size of data space */
477 #ifdef CONFIG_BRIDGE_NETFILTER
478 if (skb->nf_bridge)
479 mtu -= nf_bridge_mtu_reduction(skb);
480 #endif
481 IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE;
482
483 /* When frag_list is given, use it. First, check its validity:
484 * some transformers could create wrong frag_list or break existing
485 * one, it is not prohibited. In this case fall back to copying.
486 *
487 * LATER: this step can be merged to real generation of fragments,
488 * we can switch to copy when see the first bad fragment.
489 */
490 if (skb_has_frags(skb)) {
491 struct sk_buff *frag, *frag2;
492 int first_len = skb_pagelen(skb);
493
494 if (first_len - hlen > mtu ||
495 ((first_len - hlen) & 7) ||
496 (iph->frag_off & htons(IP_MF|IP_OFFSET)) ||
497 skb_cloned(skb))
498 goto slow_path;
499
500 skb_walk_frags(skb, frag) {
501 /* Correct geometry. */
502 if (frag->len > mtu ||
503 ((frag->len & 7) && frag->next) ||
504 skb_headroom(frag) < hlen)
505 goto slow_path_clean;
506
507 /* Partially cloned skb? */
508 if (skb_shared(frag))
509 goto slow_path_clean;
510
511 BUG_ON(frag->sk);
512 if (skb->sk) {
513 frag->sk = skb->sk;
514 frag->destructor = sock_wfree;
515 }
516 skb->truesize -= frag->truesize;
517 }
518
519 /* Everything is OK. Generate! */
520
521 err = 0;
522 offset = 0;
523 frag = skb_shinfo(skb)->frag_list;
524 skb_frag_list_init(skb);
525 skb->data_len = first_len - skb_headlen(skb);
526 skb->len = first_len;
527 iph->tot_len = htons(first_len);
528 iph->frag_off = htons(IP_MF);
529 ip_send_check(iph);
530
531 for (;;) {
532 /* Prepare header of the next frame,
533 * before previous one went down. */
534 if (frag) {
535 frag->ip_summed = CHECKSUM_NONE;
536 skb_reset_transport_header(frag);
537 __skb_push(frag, hlen);
538 skb_reset_network_header(frag);
539 memcpy(skb_network_header(frag), iph, hlen);
540 iph = ip_hdr(frag);
541 iph->tot_len = htons(frag->len);
542 ip_copy_metadata(frag, skb);
543 if (offset == 0)
544 ip_options_fragment(frag);
545 offset += skb->len - hlen;
546 iph->frag_off = htons(offset>>3);
547 if (frag->next != NULL)
548 iph->frag_off |= htons(IP_MF);
549 /* Ready, complete checksum */
550 ip_send_check(iph);
551 }
552
553 err = output(skb);
554
555 if (!err)
556 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES);
557 if (err || !frag)
558 break;
559
560 skb = frag;
561 frag = skb->next;
562 skb->next = NULL;
563 }
564
565 if (err == 0) {
566 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS);
567 return 0;
568 }
569
570 while (frag) {
571 skb = frag->next;
572 kfree_skb(frag);
573 frag = skb;
574 }
575 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
576 return err;
577
578 slow_path_clean:
579 skb_walk_frags(skb, frag2) {
580 if (frag2 == frag)
581 break;
582 frag2->sk = NULL;
583 frag2->destructor = NULL;
584 skb->truesize += frag2->truesize;
585 }
586 }
587
588 slow_path:
589 left = skb->len - hlen; /* Space per frame */
590 ptr = hlen; /* Where to start from */
591
592 /* for bridged IP traffic encapsulated inside f.e. a vlan header,
593 * we need to make room for the encapsulating header
594 */
595 ll_rs = LL_RESERVED_SPACE_EXTRA(rt->dst.dev, nf_bridge_pad(skb));
596
597 /*
598 * Fragment the datagram.
599 */
600
601 offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3;
602 not_last_frag = iph->frag_off & htons(IP_MF);
603
604 /*
605 * Keep copying data until we run out.
606 */
607
608 while (left > 0) {
609 len = left;
610 /* IF: it doesn't fit, use 'mtu' - the data space left */
611 if (len > mtu)
612 len = mtu;
613 /* IF: we are not sending upto and including the packet end
614 then align the next start on an eight byte boundary */
615 if (len < left) {
616 len &= ~7;
617 }
618 /*
619 * Allocate buffer.
620 */
621
622 if ((skb2 = alloc_skb(len+hlen+ll_rs, GFP_ATOMIC)) == NULL) {
623 NETDEBUG(KERN_INFO "IP: frag: no memory for new fragment!\n");
624 err = -ENOMEM;
625 goto fail;
626 }
627
628 /*
629 * Set up data on packet
630 */
631
632 ip_copy_metadata(skb2, skb);
633 skb_reserve(skb2, ll_rs);
634 skb_put(skb2, len + hlen);
635 skb_reset_network_header(skb2);
636 skb2->transport_header = skb2->network_header + hlen;
637
638 /*
639 * Charge the memory for the fragment to any owner
640 * it might possess
641 */
642
643 if (skb->sk)
644 skb_set_owner_w(skb2, skb->sk);
645
646 /*
647 * Copy the packet header into the new buffer.
648 */
649
650 skb_copy_from_linear_data(skb, skb_network_header(skb2), hlen);
651
652 /*
653 * Copy a block of the IP datagram.
654 */
655 if (skb_copy_bits(skb, ptr, skb_transport_header(skb2), len))
656 BUG();
657 left -= len;
658
659 /*
660 * Fill in the new header fields.
661 */
662 iph = ip_hdr(skb2);
663 iph->frag_off = htons((offset >> 3));
664
665 /* ANK: dirty, but effective trick. Upgrade options only if
666 * the segment to be fragmented was THE FIRST (otherwise,
667 * options are already fixed) and make it ONCE
668 * on the initial skb, so that all the following fragments
669 * will inherit fixed options.
670 */
671 if (offset == 0)
672 ip_options_fragment(skb);
673
674 /*
675 * Added AC : If we are fragmenting a fragment that's not the
676 * last fragment then keep MF on each bit
677 */
678 if (left > 0 || not_last_frag)
679 iph->frag_off |= htons(IP_MF);
680 ptr += len;
681 offset += len;
682
683 /*
684 * Put this fragment into the sending queue.
685 */
686 iph->tot_len = htons(len + hlen);
687
688 ip_send_check(iph);
689
690 err = output(skb2);
691 if (err)
692 goto fail;
693
694 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES);
695 }
696 kfree_skb(skb);
697 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS);
698 return err;
699
700 fail:
701 kfree_skb(skb);
702 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
703 return err;
704 }
705 EXPORT_SYMBOL(ip_fragment);
706
707 int
708 ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
709 {
710 struct iovec *iov = from;
711
712 if (skb->ip_summed == CHECKSUM_PARTIAL) {
713 if (memcpy_fromiovecend(to, iov, offset, len) < 0)
714 return -EFAULT;
715 } else {
716 __wsum csum = 0;
717 if (csum_partial_copy_fromiovecend(to, iov, offset, len, &csum) < 0)
718 return -EFAULT;
719 skb->csum = csum_block_add(skb->csum, csum, odd);
720 }
721 return 0;
722 }
723 EXPORT_SYMBOL(ip_generic_getfrag);
724
725 static inline __wsum
726 csum_page(struct page *page, int offset, int copy)
727 {
728 char *kaddr;
729 __wsum csum;
730 kaddr = kmap(page);
731 csum = csum_partial(kaddr + offset, copy, 0);
732 kunmap(page);
733 return csum;
734 }
735
736 static inline int ip_ufo_append_data(struct sock *sk,
737 int getfrag(void *from, char *to, int offset, int len,
738 int odd, struct sk_buff *skb),
739 void *from, int length, int hh_len, int fragheaderlen,
740 int transhdrlen, int mtu, unsigned int flags)
741 {
742 struct sk_buff *skb;
743 int err;
744
745 /* There is support for UDP fragmentation offload by network
746 * device, so create one single skb packet containing complete
747 * udp datagram
748 */
749 if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL) {
750 skb = sock_alloc_send_skb(sk,
751 hh_len + fragheaderlen + transhdrlen + 20,
752 (flags & MSG_DONTWAIT), &err);
753
754 if (skb == NULL)
755 return err;
756
757 /* reserve space for Hardware header */
758 skb_reserve(skb, hh_len);
759
760 /* create space for UDP/IP header */
761 skb_put(skb, fragheaderlen + transhdrlen);
762
763 /* initialize network header pointer */
764 skb_reset_network_header(skb);
765
766 /* initialize protocol header pointer */
767 skb->transport_header = skb->network_header + fragheaderlen;
768
769 skb->ip_summed = CHECKSUM_PARTIAL;
770 skb->csum = 0;
771 sk->sk_sndmsg_off = 0;
772
773 /* specify the length of each IP datagram fragment */
774 skb_shinfo(skb)->gso_size = mtu - fragheaderlen;
775 skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
776 __skb_queue_tail(&sk->sk_write_queue, skb);
777 }
778
779 return skb_append_datato_frags(sk, skb, getfrag, from,
780 (length - transhdrlen));
781 }
782
783 /*
784 * ip_append_data() and ip_append_page() can make one large IP datagram
785 * from many pieces of data. Each pieces will be holded on the socket
786 * until ip_push_pending_frames() is called. Each piece can be a page
787 * or non-page data.
788 *
789 * Not only UDP, other transport protocols - e.g. raw sockets - can use
790 * this interface potentially.
791 *
792 * LATER: length must be adjusted by pad at tail, when it is required.
793 */
794 int ip_append_data(struct sock *sk,
795 int getfrag(void *from, char *to, int offset, int len,
796 int odd, struct sk_buff *skb),
797 void *from, int length, int transhdrlen,
798 struct ipcm_cookie *ipc, struct rtable **rtp,
799 unsigned int flags)
800 {
801 struct inet_sock *inet = inet_sk(sk);
802 struct sk_buff *skb;
803
804 struct ip_options *opt = NULL;
805 int hh_len;
806 int exthdrlen;
807 int mtu;
808 int copy;
809 int err;
810 int offset = 0;
811 unsigned int maxfraglen, fragheaderlen;
812 int csummode = CHECKSUM_NONE;
813 struct rtable *rt;
814
815 if (flags&MSG_PROBE)
816 return 0;
817
818 if (skb_queue_empty(&sk->sk_write_queue)) {
819 /*
820 * setup for corking.
821 */
822 opt = ipc->opt;
823 if (opt) {
824 if (inet->cork.opt == NULL) {
825 inet->cork.opt = kmalloc(sizeof(struct ip_options) + 40, sk->sk_allocation);
826 if (unlikely(inet->cork.opt == NULL))
827 return -ENOBUFS;
828 }
829 memcpy(inet->cork.opt, opt, sizeof(struct ip_options)+opt->optlen);
830 inet->cork.flags |= IPCORK_OPT;
831 inet->cork.addr = ipc->addr;
832 }
833 rt = *rtp;
834 if (unlikely(!rt))
835 return -EFAULT;
836 /*
837 * We steal reference to this route, caller should not release it
838 */
839 *rtp = NULL;
840 inet->cork.fragsize = mtu = inet->pmtudisc == IP_PMTUDISC_PROBE ?
841 rt->dst.dev->mtu :
842 dst_mtu(rt->dst.path);
843 inet->cork.dst = &rt->dst;
844 inet->cork.length = 0;
845 sk->sk_sndmsg_page = NULL;
846 sk->sk_sndmsg_off = 0;
847 if ((exthdrlen = rt->dst.header_len) != 0) {
848 length += exthdrlen;
849 transhdrlen += exthdrlen;
850 }
851 } else {
852 rt = (struct rtable *)inet->cork.dst;
853 if (inet->cork.flags & IPCORK_OPT)
854 opt = inet->cork.opt;
855
856 transhdrlen = 0;
857 exthdrlen = 0;
858 mtu = inet->cork.fragsize;
859 }
860 hh_len = LL_RESERVED_SPACE(rt->dst.dev);
861
862 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
863 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
864
865 if (inet->cork.length + length > 0xFFFF - fragheaderlen) {
866 ip_local_error(sk, EMSGSIZE, rt->rt_dst, inet->inet_dport,
867 mtu-exthdrlen);
868 return -EMSGSIZE;
869 }
870
871 /*
872 * transhdrlen > 0 means that this is the first fragment and we wish
873 * it won't be fragmented in the future.
874 */
875 if (transhdrlen &&
876 length + fragheaderlen <= mtu &&
877 rt->dst.dev->features & NETIF_F_V4_CSUM &&
878 !exthdrlen)
879 csummode = CHECKSUM_PARTIAL;
880
881 skb = skb_peek_tail(&sk->sk_write_queue);
882
883 inet->cork.length += length;
884 if (((length > mtu) || (skb && skb_is_gso(skb))) &&
885 (sk->sk_protocol == IPPROTO_UDP) &&
886 (rt->dst.dev->features & NETIF_F_UFO)) {
887 err = ip_ufo_append_data(sk, getfrag, from, length, hh_len,
888 fragheaderlen, transhdrlen, mtu,
889 flags);
890 if (err)
891 goto error;
892 return 0;
893 }
894
895 /* So, what's going on in the loop below?
896 *
897 * We use calculated fragment length to generate chained skb,
898 * each of segments is IP fragment ready for sending to network after
899 * adding appropriate IP header.
900 */
901
902 if (!skb)
903 goto alloc_new_skb;
904
905 while (length > 0) {
906 /* Check if the remaining data fits into current packet. */
907 copy = mtu - skb->len;
908 if (copy < length)
909 copy = maxfraglen - skb->len;
910 if (copy <= 0) {
911 char *data;
912 unsigned int datalen;
913 unsigned int fraglen;
914 unsigned int fraggap;
915 unsigned int alloclen;
916 struct sk_buff *skb_prev;
917 alloc_new_skb:
918 skb_prev = skb;
919 if (skb_prev)
920 fraggap = skb_prev->len - maxfraglen;
921 else
922 fraggap = 0;
923
924 /*
925 * If remaining data exceeds the mtu,
926 * we know we need more fragment(s).
927 */
928 datalen = length + fraggap;
929 if (datalen > mtu - fragheaderlen)
930 datalen = maxfraglen - fragheaderlen;
931 fraglen = datalen + fragheaderlen;
932
933 if ((flags & MSG_MORE) &&
934 !(rt->dst.dev->features&NETIF_F_SG))
935 alloclen = mtu;
936 else
937 alloclen = datalen + fragheaderlen;
938
939 /* The last fragment gets additional space at tail.
940 * Note, with MSG_MORE we overallocate on fragments,
941 * because we have no idea what fragment will be
942 * the last.
943 */
944 if (datalen == length + fraggap)
945 alloclen += rt->dst.trailer_len;
946
947 if (transhdrlen) {
948 skb = sock_alloc_send_skb(sk,
949 alloclen + hh_len + 15,
950 (flags & MSG_DONTWAIT), &err);
951 } else {
952 skb = NULL;
953 if (atomic_read(&sk->sk_wmem_alloc) <=
954 2 * sk->sk_sndbuf)
955 skb = sock_wmalloc(sk,
956 alloclen + hh_len + 15, 1,
957 sk->sk_allocation);
958 if (unlikely(skb == NULL))
959 err = -ENOBUFS;
960 else
961 /* only the initial fragment is
962 time stamped */
963 ipc->shtx.flags = 0;
964 }
965 if (skb == NULL)
966 goto error;
967
968 /*
969 * Fill in the control structures
970 */
971 skb->ip_summed = csummode;
972 skb->csum = 0;
973 skb_reserve(skb, hh_len);
974 *skb_tx(skb) = ipc->shtx;
975
976 /*
977 * Find where to start putting bytes.
978 */
979 data = skb_put(skb, fraglen);
980 skb_set_network_header(skb, exthdrlen);
981 skb->transport_header = (skb->network_header +
982 fragheaderlen);
983 data += fragheaderlen;
984
985 if (fraggap) {
986 skb->csum = skb_copy_and_csum_bits(
987 skb_prev, maxfraglen,
988 data + transhdrlen, fraggap, 0);
989 skb_prev->csum = csum_sub(skb_prev->csum,
990 skb->csum);
991 data += fraggap;
992 pskb_trim_unique(skb_prev, maxfraglen);
993 }
994
995 copy = datalen - transhdrlen - fraggap;
996 if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) {
997 err = -EFAULT;
998 kfree_skb(skb);
999 goto error;
1000 }
1001
1002 offset += copy;
1003 length -= datalen - fraggap;
1004 transhdrlen = 0;
1005 exthdrlen = 0;
1006 csummode = CHECKSUM_NONE;
1007
1008 /*
1009 * Put the packet on the pending queue.
1010 */
1011 __skb_queue_tail(&sk->sk_write_queue, skb);
1012 continue;
1013 }
1014
1015 if (copy > length)
1016 copy = length;
1017
1018 if (!(rt->dst.dev->features&NETIF_F_SG)) {
1019 unsigned int off;
1020
1021 off = skb->len;
1022 if (getfrag(from, skb_put(skb, copy),
1023 offset, copy, off, skb) < 0) {
1024 __skb_trim(skb, off);
1025 err = -EFAULT;
1026 goto error;
1027 }
1028 } else {
1029 int i = skb_shinfo(skb)->nr_frags;
1030 skb_frag_t *frag = &skb_shinfo(skb)->frags[i-1];
1031 struct page *page = sk->sk_sndmsg_page;
1032 int off = sk->sk_sndmsg_off;
1033 unsigned int left;
1034
1035 if (page && (left = PAGE_SIZE - off) > 0) {
1036 if (copy >= left)
1037 copy = left;
1038 if (page != frag->page) {
1039 if (i == MAX_SKB_FRAGS) {
1040 err = -EMSGSIZE;
1041 goto error;
1042 }
1043 get_page(page);
1044 skb_fill_page_desc(skb, i, page, sk->sk_sndmsg_off, 0);
1045 frag = &skb_shinfo(skb)->frags[i];
1046 }
1047 } else if (i < MAX_SKB_FRAGS) {
1048 if (copy > PAGE_SIZE)
1049 copy = PAGE_SIZE;
1050 page = alloc_pages(sk->sk_allocation, 0);
1051 if (page == NULL) {
1052 err = -ENOMEM;
1053 goto error;
1054 }
1055 sk->sk_sndmsg_page = page;
1056 sk->sk_sndmsg_off = 0;
1057
1058 skb_fill_page_desc(skb, i, page, 0, 0);
1059 frag = &skb_shinfo(skb)->frags[i];
1060 } else {
1061 err = -EMSGSIZE;
1062 goto error;
1063 }
1064 if (getfrag(from, page_address(frag->page)+frag->page_offset+frag->size, offset, copy, skb->len, skb) < 0) {
1065 err = -EFAULT;
1066 goto error;
1067 }
1068 sk->sk_sndmsg_off += copy;
1069 frag->size += copy;
1070 skb->len += copy;
1071 skb->data_len += copy;
1072 skb->truesize += copy;
1073 atomic_add(copy, &sk->sk_wmem_alloc);
1074 }
1075 offset += copy;
1076 length -= copy;
1077 }
1078
1079 return 0;
1080
1081 error:
1082 inet->cork.length -= length;
1083 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1084 return err;
1085 }
1086
1087 ssize_t ip_append_page(struct sock *sk, struct page *page,
1088 int offset, size_t size, int flags)
1089 {
1090 struct inet_sock *inet = inet_sk(sk);
1091 struct sk_buff *skb;
1092 struct rtable *rt;
1093 struct ip_options *opt = NULL;
1094 int hh_len;
1095 int mtu;
1096 int len;
1097 int err;
1098 unsigned int maxfraglen, fragheaderlen, fraggap;
1099
1100 if (inet->hdrincl)
1101 return -EPERM;
1102
1103 if (flags&MSG_PROBE)
1104 return 0;
1105
1106 if (skb_queue_empty(&sk->sk_write_queue))
1107 return -EINVAL;
1108
1109 rt = (struct rtable *)inet->cork.dst;
1110 if (inet->cork.flags & IPCORK_OPT)
1111 opt = inet->cork.opt;
1112
1113 if (!(rt->dst.dev->features&NETIF_F_SG))
1114 return -EOPNOTSUPP;
1115
1116 hh_len = LL_RESERVED_SPACE(rt->dst.dev);
1117 mtu = inet->cork.fragsize;
1118
1119 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
1120 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
1121
1122 if (inet->cork.length + size > 0xFFFF - fragheaderlen) {
1123 ip_local_error(sk, EMSGSIZE, rt->rt_dst, inet->inet_dport, mtu);
1124 return -EMSGSIZE;
1125 }
1126
1127 if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL)
1128 return -EINVAL;
1129
1130 inet->cork.length += size;
1131 if ((size + skb->len > mtu) &&
1132 (sk->sk_protocol == IPPROTO_UDP) &&
1133 (rt->dst.dev->features & NETIF_F_UFO)) {
1134 skb_shinfo(skb)->gso_size = mtu - fragheaderlen;
1135 skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
1136 }
1137
1138
1139 while (size > 0) {
1140 int i;
1141
1142 if (skb_is_gso(skb))
1143 len = size;
1144 else {
1145
1146 /* Check if the remaining data fits into current packet. */
1147 len = mtu - skb->len;
1148 if (len < size)
1149 len = maxfraglen - skb->len;
1150 }
1151 if (len <= 0) {
1152 struct sk_buff *skb_prev;
1153 int alloclen;
1154
1155 skb_prev = skb;
1156 fraggap = skb_prev->len - maxfraglen;
1157
1158 alloclen = fragheaderlen + hh_len + fraggap + 15;
1159 skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation);
1160 if (unlikely(!skb)) {
1161 err = -ENOBUFS;
1162 goto error;
1163 }
1164
1165 /*
1166 * Fill in the control structures
1167 */
1168 skb->ip_summed = CHECKSUM_NONE;
1169 skb->csum = 0;
1170 skb_reserve(skb, hh_len);
1171
1172 /*
1173 * Find where to start putting bytes.
1174 */
1175 skb_put(skb, fragheaderlen + fraggap);
1176 skb_reset_network_header(skb);
1177 skb->transport_header = (skb->network_header +
1178 fragheaderlen);
1179 if (fraggap) {
1180 skb->csum = skb_copy_and_csum_bits(skb_prev,
1181 maxfraglen,
1182 skb_transport_header(skb),
1183 fraggap, 0);
1184 skb_prev->csum = csum_sub(skb_prev->csum,
1185 skb->csum);
1186 pskb_trim_unique(skb_prev, maxfraglen);
1187 }
1188
1189 /*
1190 * Put the packet on the pending queue.
1191 */
1192 __skb_queue_tail(&sk->sk_write_queue, skb);
1193 continue;
1194 }
1195
1196 i = skb_shinfo(skb)->nr_frags;
1197 if (len > size)
1198 len = size;
1199 if (skb_can_coalesce(skb, i, page, offset)) {
1200 skb_shinfo(skb)->frags[i-1].size += len;
1201 } else if (i < MAX_SKB_FRAGS) {
1202 get_page(page);
1203 skb_fill_page_desc(skb, i, page, offset, len);
1204 } else {
1205 err = -EMSGSIZE;
1206 goto error;
1207 }
1208
1209 if (skb->ip_summed == CHECKSUM_NONE) {
1210 __wsum csum;
1211 csum = csum_page(page, offset, len);
1212 skb->csum = csum_block_add(skb->csum, csum, skb->len);
1213 }
1214
1215 skb->len += len;
1216 skb->data_len += len;
1217 skb->truesize += len;
1218 atomic_add(len, &sk->sk_wmem_alloc);
1219 offset += len;
1220 size -= len;
1221 }
1222 return 0;
1223
1224 error:
1225 inet->cork.length -= size;
1226 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1227 return err;
1228 }
1229
1230 static void ip_cork_release(struct inet_sock *inet)
1231 {
1232 inet->cork.flags &= ~IPCORK_OPT;
1233 kfree(inet->cork.opt);
1234 inet->cork.opt = NULL;
1235 dst_release(inet->cork.dst);
1236 inet->cork.dst = NULL;
1237 }
1238
1239 /*
1240 * Combined all pending IP fragments on the socket as one IP datagram
1241 * and push them out.
1242 */
1243 int ip_push_pending_frames(struct sock *sk)
1244 {
1245 struct sk_buff *skb, *tmp_skb;
1246 struct sk_buff **tail_skb;
1247 struct inet_sock *inet = inet_sk(sk);
1248 struct net *net = sock_net(sk);
1249 struct ip_options *opt = NULL;
1250 struct rtable *rt = (struct rtable *)inet->cork.dst;
1251 struct iphdr *iph;
1252 __be16 df = 0;
1253 __u8 ttl;
1254 int err = 0;
1255
1256 if ((skb = __skb_dequeue(&sk->sk_write_queue)) == NULL)
1257 goto out;
1258 tail_skb = &(skb_shinfo(skb)->frag_list);
1259
1260 /* move skb->data to ip header from ext header */
1261 if (skb->data < skb_network_header(skb))
1262 __skb_pull(skb, skb_network_offset(skb));
1263 while ((tmp_skb = __skb_dequeue(&sk->sk_write_queue)) != NULL) {
1264 __skb_pull(tmp_skb, skb_network_header_len(skb));
1265 *tail_skb = tmp_skb;
1266 tail_skb = &(tmp_skb->next);
1267 skb->len += tmp_skb->len;
1268 skb->data_len += tmp_skb->len;
1269 skb->truesize += tmp_skb->truesize;
1270 tmp_skb->destructor = NULL;
1271 tmp_skb->sk = NULL;
1272 }
1273
1274 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow
1275 * to fragment the frame generated here. No matter, what transforms
1276 * how transforms change size of the packet, it will come out.
1277 */
1278 if (inet->pmtudisc < IP_PMTUDISC_DO)
1279 skb->local_df = 1;
1280
1281 /* DF bit is set when we want to see DF on outgoing frames.
1282 * If local_df is set too, we still allow to fragment this frame
1283 * locally. */
1284 if (inet->pmtudisc >= IP_PMTUDISC_DO ||
1285 (skb->len <= dst_mtu(&rt->dst) &&
1286 ip_dont_fragment(sk, &rt->dst)))
1287 df = htons(IP_DF);
1288
1289 if (inet->cork.flags & IPCORK_OPT)
1290 opt = inet->cork.opt;
1291
1292 if (rt->rt_type == RTN_MULTICAST)
1293 ttl = inet->mc_ttl;
1294 else
1295 ttl = ip_select_ttl(inet, &rt->dst);
1296
1297 iph = (struct iphdr *)skb->data;
1298 iph->version = 4;
1299 iph->ihl = 5;
1300 if (opt) {
1301 iph->ihl += opt->optlen>>2;
1302 ip_options_build(skb, opt, inet->cork.addr, rt, 0);
1303 }
1304 iph->tos = inet->tos;
1305 iph->frag_off = df;
1306 ip_select_ident(iph, &rt->dst, sk);
1307 iph->ttl = ttl;
1308 iph->protocol = sk->sk_protocol;
1309 iph->saddr = rt->rt_src;
1310 iph->daddr = rt->rt_dst;
1311
1312 skb->priority = sk->sk_priority;
1313 skb->mark = sk->sk_mark;
1314 /*
1315 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec
1316 * on dst refcount
1317 */
1318 inet->cork.dst = NULL;
1319 skb_dst_set(skb, &rt->dst);
1320
1321 if (iph->protocol == IPPROTO_ICMP)
1322 icmp_out_count(net, ((struct icmphdr *)
1323 skb_transport_header(skb))->type);
1324
1325 /* Netfilter gets whole the not fragmented skb. */
1326 err = ip_local_out(skb);
1327 if (err) {
1328 if (err > 0)
1329 err = net_xmit_errno(err);
1330 if (err)
1331 goto error;
1332 }
1333
1334 out:
1335 ip_cork_release(inet);
1336 return err;
1337
1338 error:
1339 IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS);
1340 goto out;
1341 }
1342
1343 /*
1344 * Throw away all pending data on the socket.
1345 */
1346 void ip_flush_pending_frames(struct sock *sk)
1347 {
1348 struct sk_buff *skb;
1349
1350 while ((skb = __skb_dequeue_tail(&sk->sk_write_queue)) != NULL)
1351 kfree_skb(skb);
1352
1353 ip_cork_release(inet_sk(sk));
1354 }
1355
1356
1357 /*
1358 * Fetch data from kernel space and fill in checksum if needed.
1359 */
1360 static int ip_reply_glue_bits(void *dptr, char *to, int offset,
1361 int len, int odd, struct sk_buff *skb)
1362 {
1363 __wsum csum;
1364
1365 csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0);
1366 skb->csum = csum_block_add(skb->csum, csum, odd);
1367 return 0;
1368 }
1369
1370 /*
1371 * Generic function to send a packet as reply to another packet.
1372 * Used to send TCP resets so far. ICMP should use this function too.
1373 *
1374 * Should run single threaded per socket because it uses the sock
1375 * structure to pass arguments.
1376 */
1377 void ip_send_reply(struct sock *sk, struct sk_buff *skb, struct ip_reply_arg *arg,
1378 unsigned int len)
1379 {
1380 struct inet_sock *inet = inet_sk(sk);
1381 struct {
1382 struct ip_options opt;
1383 char data[40];
1384 } replyopts;
1385 struct ipcm_cookie ipc;
1386 __be32 daddr;
1387 struct rtable *rt = skb_rtable(skb);
1388
1389 if (ip_options_echo(&replyopts.opt, skb))
1390 return;
1391
1392 daddr = ipc.addr = rt->rt_src;
1393 ipc.opt = NULL;
1394 ipc.shtx.flags = 0;
1395
1396 if (replyopts.opt.optlen) {
1397 ipc.opt = &replyopts.opt;
1398
1399 if (ipc.opt->srr)
1400 daddr = replyopts.opt.faddr;
1401 }
1402
1403 {
1404 struct flowi fl = { .oif = arg->bound_dev_if,
1405 .nl_u = { .ip4_u =
1406 { .daddr = daddr,
1407 .saddr = rt->rt_spec_dst,
1408 .tos = RT_TOS(ip_hdr(skb)->tos) } },
1409 /* Not quite clean, but right. */
1410 .uli_u = { .ports =
1411 { .sport = tcp_hdr(skb)->dest,
1412 .dport = tcp_hdr(skb)->source } },
1413 .proto = sk->sk_protocol,
1414 .flags = ip_reply_arg_flowi_flags(arg) };
1415 security_skb_classify_flow(skb, &fl);
1416 if (ip_route_output_key(sock_net(sk), &rt, &fl))
1417 return;
1418 }
1419
1420 /* And let IP do all the hard work.
1421
1422 This chunk is not reenterable, hence spinlock.
1423 Note that it uses the fact, that this function is called
1424 with locally disabled BH and that sk cannot be already spinlocked.
1425 */
1426 bh_lock_sock(sk);
1427 inet->tos = ip_hdr(skb)->tos;
1428 sk->sk_priority = skb->priority;
1429 sk->sk_protocol = ip_hdr(skb)->protocol;
1430 sk->sk_bound_dev_if = arg->bound_dev_if;
1431 ip_append_data(sk, ip_reply_glue_bits, arg->iov->iov_base, len, 0,
1432 &ipc, &rt, MSG_DONTWAIT);
1433 if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
1434 if (arg->csumoffset >= 0)
1435 *((__sum16 *)skb_transport_header(skb) +
1436 arg->csumoffset) = csum_fold(csum_add(skb->csum,
1437 arg->csum));
1438 skb->ip_summed = CHECKSUM_NONE;
1439 ip_push_pending_frames(sk);
1440 }
1441
1442 bh_unlock_sock(sk);
1443
1444 ip_rt_put(rt);
1445 }
1446
1447 void __init ip_init(void)
1448 {
1449 ip_rt_init();
1450 inet_initpeers();
1451
1452 #if defined(CONFIG_IP_MULTICAST) && defined(CONFIG_PROC_FS)
1453 igmp_mc_proc_init();
1454 #endif
1455 }
Linux kernel - Deliverables
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