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net: more Kconfig whitespace cleanup
[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_frag_list(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 exthdrlen = rt->dst.header_len;
848 length += exthdrlen;
849 transhdrlen += exthdrlen;
850 } else {
851 rt = (struct rtable *)inet->cork.dst;
852 if (inet->cork.flags & IPCORK_OPT)
853 opt = inet->cork.opt;
854
855 transhdrlen = 0;
856 exthdrlen = 0;
857 mtu = inet->cork.fragsize;
858 }
859 hh_len = LL_RESERVED_SPACE(rt->dst.dev);
860
861 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
862 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
863
864 if (inet->cork.length + length > 0xFFFF - fragheaderlen) {
865 ip_local_error(sk, EMSGSIZE, rt->rt_dst, inet->inet_dport,
866 mtu-exthdrlen);
867 return -EMSGSIZE;
868 }
869
870 /*
871 * transhdrlen > 0 means that this is the first fragment and we wish
872 * it won't be fragmented in the future.
873 */
874 if (transhdrlen &&
875 length + fragheaderlen <= mtu &&
876 rt->dst.dev->features & NETIF_F_V4_CSUM &&
877 !exthdrlen)
878 csummode = CHECKSUM_PARTIAL;
879
880 skb = skb_peek_tail(&sk->sk_write_queue);
881
882 inet->cork.length += length;
883 if (((length > mtu) || (skb && skb_is_gso(skb))) &&
884 (sk->sk_protocol == IPPROTO_UDP) &&
885 (rt->dst.dev->features & NETIF_F_UFO)) {
886 err = ip_ufo_append_data(sk, getfrag, from, length, hh_len,
887 fragheaderlen, transhdrlen, mtu,
888 flags);
889 if (err)
890 goto error;
891 return 0;
892 }
893
894 /* So, what's going on in the loop below?
895 *
896 * We use calculated fragment length to generate chained skb,
897 * each of segments is IP fragment ready for sending to network after
898 * adding appropriate IP header.
899 */
900
901 if (!skb)
902 goto alloc_new_skb;
903
904 while (length > 0) {
905 /* Check if the remaining data fits into current packet. */
906 copy = mtu - skb->len;
907 if (copy < length)
908 copy = maxfraglen - skb->len;
909 if (copy <= 0) {
910 char *data;
911 unsigned int datalen;
912 unsigned int fraglen;
913 unsigned int fraggap;
914 unsigned int alloclen;
915 struct sk_buff *skb_prev;
916 alloc_new_skb:
917 skb_prev = skb;
918 if (skb_prev)
919 fraggap = skb_prev->len - maxfraglen;
920 else
921 fraggap = 0;
922
923 /*
924 * If remaining data exceeds the mtu,
925 * we know we need more fragment(s).
926 */
927 datalen = length + fraggap;
928 if (datalen > mtu - fragheaderlen)
929 datalen = maxfraglen - fragheaderlen;
930 fraglen = datalen + fragheaderlen;
931
932 if ((flags & MSG_MORE) &&
933 !(rt->dst.dev->features&NETIF_F_SG))
934 alloclen = mtu;
935 else
936 alloclen = fraglen;
937
938 /* The last fragment gets additional space at tail.
939 * Note, with MSG_MORE we overallocate on fragments,
940 * because we have no idea what fragment will be
941 * the last.
942 */
943 if (datalen == length + fraggap) {
944 alloclen += rt->dst.trailer_len;
945 /* make sure mtu is not reached */
946 if (datalen > mtu - fragheaderlen - rt->dst.trailer_len)
947 datalen -= ALIGN(rt->dst.trailer_len, 8);
948 }
949 if (transhdrlen) {
950 skb = sock_alloc_send_skb(sk,
951 alloclen + hh_len + 15,
952 (flags & MSG_DONTWAIT), &err);
953 } else {
954 skb = NULL;
955 if (atomic_read(&sk->sk_wmem_alloc) <=
956 2 * sk->sk_sndbuf)
957 skb = sock_wmalloc(sk,
958 alloclen + hh_len + 15, 1,
959 sk->sk_allocation);
960 if (unlikely(skb == NULL))
961 err = -ENOBUFS;
962 else
963 /* only the initial fragment is
964 time stamped */
965 ipc->tx_flags = 0;
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 skb_shinfo(skb)->tx_flags = ipc->tx_flags;
977
978 /*
979 * Find where to start putting bytes.
980 */
981 data = skb_put(skb, fraglen);
982 skb_set_network_header(skb, exthdrlen);
983 skb->transport_header = (skb->network_header +
984 fragheaderlen);
985 data += fragheaderlen;
986
987 if (fraggap) {
988 skb->csum = skb_copy_and_csum_bits(
989 skb_prev, maxfraglen,
990 data + transhdrlen, fraggap, 0);
991 skb_prev->csum = csum_sub(skb_prev->csum,
992 skb->csum);
993 data += fraggap;
994 pskb_trim_unique(skb_prev, maxfraglen);
995 }
996
997 copy = datalen - transhdrlen - fraggap;
998 if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) {
999 err = -EFAULT;
1000 kfree_skb(skb);
1001 goto error;
1002 }
1003
1004 offset += copy;
1005 length -= datalen - fraggap;
1006 transhdrlen = 0;
1007 exthdrlen = 0;
1008 csummode = CHECKSUM_NONE;
1009
1010 /*
1011 * Put the packet on the pending queue.
1012 */
1013 __skb_queue_tail(&sk->sk_write_queue, skb);
1014 continue;
1015 }
1016
1017 if (copy > length)
1018 copy = length;
1019
1020 if (!(rt->dst.dev->features&NETIF_F_SG)) {
1021 unsigned int off;
1022
1023 off = skb->len;
1024 if (getfrag(from, skb_put(skb, copy),
1025 offset, copy, off, skb) < 0) {
1026 __skb_trim(skb, off);
1027 err = -EFAULT;
1028 goto error;
1029 }
1030 } else {
1031 int i = skb_shinfo(skb)->nr_frags;
1032 skb_frag_t *frag = &skb_shinfo(skb)->frags[i-1];
1033 struct page *page = sk->sk_sndmsg_page;
1034 int off = sk->sk_sndmsg_off;
1035 unsigned int left;
1036
1037 if (page && (left = PAGE_SIZE - off) > 0) {
1038 if (copy >= left)
1039 copy = left;
1040 if (page != frag->page) {
1041 if (i == MAX_SKB_FRAGS) {
1042 err = -EMSGSIZE;
1043 goto error;
1044 }
1045 get_page(page);
1046 skb_fill_page_desc(skb, i, page, sk->sk_sndmsg_off, 0);
1047 frag = &skb_shinfo(skb)->frags[i];
1048 }
1049 } else if (i < MAX_SKB_FRAGS) {
1050 if (copy > PAGE_SIZE)
1051 copy = PAGE_SIZE;
1052 page = alloc_pages(sk->sk_allocation, 0);
1053 if (page == NULL) {
1054 err = -ENOMEM;
1055 goto error;
1056 }
1057 sk->sk_sndmsg_page = page;
1058 sk->sk_sndmsg_off = 0;
1059
1060 skb_fill_page_desc(skb, i, page, 0, 0);
1061 frag = &skb_shinfo(skb)->frags[i];
1062 } else {
1063 err = -EMSGSIZE;
1064 goto error;
1065 }
1066 if (getfrag(from, page_address(frag->page)+frag->page_offset+frag->size, offset, copy, skb->len, skb) < 0) {
1067 err = -EFAULT;
1068 goto error;
1069 }
1070 sk->sk_sndmsg_off += copy;
1071 frag->size += copy;
1072 skb->len += copy;
1073 skb->data_len += copy;
1074 skb->truesize += copy;
1075 atomic_add(copy, &sk->sk_wmem_alloc);
1076 }
1077 offset += copy;
1078 length -= copy;
1079 }
1080
1081 return 0;
1082
1083 error:
1084 inet->cork.length -= length;
1085 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1086 return err;
1087 }
1088
1089 ssize_t ip_append_page(struct sock *sk, struct page *page,
1090 int offset, size_t size, int flags)
1091 {
1092 struct inet_sock *inet = inet_sk(sk);
1093 struct sk_buff *skb;
1094 struct rtable *rt;
1095 struct ip_options *opt = NULL;
1096 int hh_len;
1097 int mtu;
1098 int len;
1099 int err;
1100 unsigned int maxfraglen, fragheaderlen, fraggap;
1101
1102 if (inet->hdrincl)
1103 return -EPERM;
1104
1105 if (flags&MSG_PROBE)
1106 return 0;
1107
1108 if (skb_queue_empty(&sk->sk_write_queue))
1109 return -EINVAL;
1110
1111 rt = (struct rtable *)inet->cork.dst;
1112 if (inet->cork.flags & IPCORK_OPT)
1113 opt = inet->cork.opt;
1114
1115 if (!(rt->dst.dev->features&NETIF_F_SG))
1116 return -EOPNOTSUPP;
1117
1118 hh_len = LL_RESERVED_SPACE(rt->dst.dev);
1119 mtu = inet->cork.fragsize;
1120
1121 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
1122 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
1123
1124 if (inet->cork.length + size > 0xFFFF - fragheaderlen) {
1125 ip_local_error(sk, EMSGSIZE, rt->rt_dst, inet->inet_dport, mtu);
1126 return -EMSGSIZE;
1127 }
1128
1129 if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL)
1130 return -EINVAL;
1131
1132 inet->cork.length += size;
1133 if ((size + skb->len > mtu) &&
1134 (sk->sk_protocol == IPPROTO_UDP) &&
1135 (rt->dst.dev->features & NETIF_F_UFO)) {
1136 skb_shinfo(skb)->gso_size = mtu - fragheaderlen;
1137 skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
1138 }
1139
1140
1141 while (size > 0) {
1142 int i;
1143
1144 if (skb_is_gso(skb))
1145 len = size;
1146 else {
1147
1148 /* Check if the remaining data fits into current packet. */
1149 len = mtu - skb->len;
1150 if (len < size)
1151 len = maxfraglen - skb->len;
1152 }
1153 if (len <= 0) {
1154 struct sk_buff *skb_prev;
1155 int alloclen;
1156
1157 skb_prev = skb;
1158 fraggap = skb_prev->len - maxfraglen;
1159
1160 alloclen = fragheaderlen + hh_len + fraggap + 15;
1161 skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation);
1162 if (unlikely(!skb)) {
1163 err = -ENOBUFS;
1164 goto error;
1165 }
1166
1167 /*
1168 * Fill in the control structures
1169 */
1170 skb->ip_summed = CHECKSUM_NONE;
1171 skb->csum = 0;
1172 skb_reserve(skb, hh_len);
1173
1174 /*
1175 * Find where to start putting bytes.
1176 */
1177 skb_put(skb, fragheaderlen + fraggap);
1178 skb_reset_network_header(skb);
1179 skb->transport_header = (skb->network_header +
1180 fragheaderlen);
1181 if (fraggap) {
1182 skb->csum = skb_copy_and_csum_bits(skb_prev,
1183 maxfraglen,
1184 skb_transport_header(skb),
1185 fraggap, 0);
1186 skb_prev->csum = csum_sub(skb_prev->csum,
1187 skb->csum);
1188 pskb_trim_unique(skb_prev, maxfraglen);
1189 }
1190
1191 /*
1192 * Put the packet on the pending queue.
1193 */
1194 __skb_queue_tail(&sk->sk_write_queue, skb);
1195 continue;
1196 }
1197
1198 i = skb_shinfo(skb)->nr_frags;
1199 if (len > size)
1200 len = size;
1201 if (skb_can_coalesce(skb, i, page, offset)) {
1202 skb_shinfo(skb)->frags[i-1].size += len;
1203 } else if (i < MAX_SKB_FRAGS) {
1204 get_page(page);
1205 skb_fill_page_desc(skb, i, page, offset, len);
1206 } else {
1207 err = -EMSGSIZE;
1208 goto error;
1209 }
1210
1211 if (skb->ip_summed == CHECKSUM_NONE) {
1212 __wsum csum;
1213 csum = csum_page(page, offset, len);
1214 skb->csum = csum_block_add(skb->csum, csum, skb->len);
1215 }
1216
1217 skb->len += len;
1218 skb->data_len += len;
1219 skb->truesize += len;
1220 atomic_add(len, &sk->sk_wmem_alloc);
1221 offset += len;
1222 size -= len;
1223 }
1224 return 0;
1225
1226 error:
1227 inet->cork.length -= size;
1228 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1229 return err;
1230 }
1231
1232 static void ip_cork_release(struct inet_sock *inet)
1233 {
1234 inet->cork.flags &= ~IPCORK_OPT;
1235 kfree(inet->cork.opt);
1236 inet->cork.opt = NULL;
1237 dst_release(inet->cork.dst);
1238 inet->cork.dst = NULL;
1239 }
1240
1241 /*
1242 * Combined all pending IP fragments on the socket as one IP datagram
1243 * and push them out.
1244 */
1245 int ip_push_pending_frames(struct sock *sk)
1246 {
1247 struct sk_buff *skb, *tmp_skb;
1248 struct sk_buff **tail_skb;
1249 struct inet_sock *inet = inet_sk(sk);
1250 struct net *net = sock_net(sk);
1251 struct ip_options *opt = NULL;
1252 struct rtable *rt = (struct rtable *)inet->cork.dst;
1253 struct iphdr *iph;
1254 __be16 df = 0;
1255 __u8 ttl;
1256 int err = 0;
1257
1258 if ((skb = __skb_dequeue(&sk->sk_write_queue)) == NULL)
1259 goto out;
1260 tail_skb = &(skb_shinfo(skb)->frag_list);
1261
1262 /* move skb->data to ip header from ext header */
1263 if (skb->data < skb_network_header(skb))
1264 __skb_pull(skb, skb_network_offset(skb));
1265 while ((tmp_skb = __skb_dequeue(&sk->sk_write_queue)) != NULL) {
1266 __skb_pull(tmp_skb, skb_network_header_len(skb));
1267 *tail_skb = tmp_skb;
1268 tail_skb = &(tmp_skb->next);
1269 skb->len += tmp_skb->len;
1270 skb->data_len += tmp_skb->len;
1271 skb->truesize += tmp_skb->truesize;
1272 tmp_skb->destructor = NULL;
1273 tmp_skb->sk = NULL;
1274 }
1275
1276 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow
1277 * to fragment the frame generated here. No matter, what transforms
1278 * how transforms change size of the packet, it will come out.
1279 */
1280 if (inet->pmtudisc < IP_PMTUDISC_DO)
1281 skb->local_df = 1;
1282
1283 /* DF bit is set when we want to see DF on outgoing frames.
1284 * If local_df is set too, we still allow to fragment this frame
1285 * locally. */
1286 if (inet->pmtudisc >= IP_PMTUDISC_DO ||
1287 (skb->len <= dst_mtu(&rt->dst) &&
1288 ip_dont_fragment(sk, &rt->dst)))
1289 df = htons(IP_DF);
1290
1291 if (inet->cork.flags & IPCORK_OPT)
1292 opt = inet->cork.opt;
1293
1294 if (rt->rt_type == RTN_MULTICAST)
1295 ttl = inet->mc_ttl;
1296 else
1297 ttl = ip_select_ttl(inet, &rt->dst);
1298
1299 iph = (struct iphdr *)skb->data;
1300 iph->version = 4;
1301 iph->ihl = 5;
1302 if (opt) {
1303 iph->ihl += opt->optlen>>2;
1304 ip_options_build(skb, opt, inet->cork.addr, rt, 0);
1305 }
1306 iph->tos = inet->tos;
1307 iph->frag_off = df;
1308 ip_select_ident(iph, &rt->dst, sk);
1309 iph->ttl = ttl;
1310 iph->protocol = sk->sk_protocol;
1311 iph->saddr = rt->rt_src;
1312 iph->daddr = rt->rt_dst;
1313
1314 skb->priority = sk->sk_priority;
1315 skb->mark = sk->sk_mark;
1316 /*
1317 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec
1318 * on dst refcount
1319 */
1320 inet->cork.dst = NULL;
1321 skb_dst_set(skb, &rt->dst);
1322
1323 if (iph->protocol == IPPROTO_ICMP)
1324 icmp_out_count(net, ((struct icmphdr *)
1325 skb_transport_header(skb))->type);
1326
1327 /* Netfilter gets whole the not fragmented skb. */
1328 err = ip_local_out(skb);
1329 if (err) {
1330 if (err > 0)
1331 err = net_xmit_errno(err);
1332 if (err)
1333 goto error;
1334 }
1335
1336 out:
1337 ip_cork_release(inet);
1338 return err;
1339
1340 error:
1341 IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS);
1342 goto out;
1343 }
1344
1345 /*
1346 * Throw away all pending data on the socket.
1347 */
1348 void ip_flush_pending_frames(struct sock *sk)
1349 {
1350 struct sk_buff *skb;
1351
1352 while ((skb = __skb_dequeue_tail(&sk->sk_write_queue)) != NULL)
1353 kfree_skb(skb);
1354
1355 ip_cork_release(inet_sk(sk));
1356 }
1357
1358
1359 /*
1360 * Fetch data from kernel space and fill in checksum if needed.
1361 */
1362 static int ip_reply_glue_bits(void *dptr, char *to, int offset,
1363 int len, int odd, struct sk_buff *skb)
1364 {
1365 __wsum csum;
1366
1367 csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0);
1368 skb->csum = csum_block_add(skb->csum, csum, odd);
1369 return 0;
1370 }
1371
1372 /*
1373 * Generic function to send a packet as reply to another packet.
1374 * Used to send TCP resets so far. ICMP should use this function too.
1375 *
1376 * Should run single threaded per socket because it uses the sock
1377 * structure to pass arguments.
1378 */
1379 void ip_send_reply(struct sock *sk, struct sk_buff *skb, struct ip_reply_arg *arg,
1380 unsigned int len)
1381 {
1382 struct inet_sock *inet = inet_sk(sk);
1383 struct {
1384 struct ip_options opt;
1385 char data[40];
1386 } replyopts;
1387 struct ipcm_cookie ipc;
1388 __be32 daddr;
1389 struct rtable *rt = skb_rtable(skb);
1390
1391 if (ip_options_echo(&replyopts.opt, skb))
1392 return;
1393
1394 daddr = ipc.addr = rt->rt_src;
1395 ipc.opt = NULL;
1396 ipc.tx_flags = 0;
1397
1398 if (replyopts.opt.optlen) {
1399 ipc.opt = &replyopts.opt;
1400
1401 if (ipc.opt->srr)
1402 daddr = replyopts.opt.faddr;
1403 }
1404
1405 {
1406 struct flowi fl = { .oif = arg->bound_dev_if,
1407 .nl_u = { .ip4_u =
1408 { .daddr = daddr,
1409 .saddr = rt->rt_spec_dst,
1410 .tos = RT_TOS(ip_hdr(skb)->tos) } },
1411 /* Not quite clean, but right. */
1412 .uli_u = { .ports =
1413 { .sport = tcp_hdr(skb)->dest,
1414 .dport = tcp_hdr(skb)->source } },
1415 .proto = sk->sk_protocol,
1416 .flags = ip_reply_arg_flowi_flags(arg) };
1417 security_skb_classify_flow(skb, &fl);
1418 if (ip_route_output_key(sock_net(sk), &rt, &fl))
1419 return;
1420 }
1421
1422 /* And let IP do all the hard work.
1423
1424 This chunk is not reenterable, hence spinlock.
1425 Note that it uses the fact, that this function is called
1426 with locally disabled BH and that sk cannot be already spinlocked.
1427 */
1428 bh_lock_sock(sk);
1429 inet->tos = ip_hdr(skb)->tos;
1430 sk->sk_priority = skb->priority;
1431 sk->sk_protocol = ip_hdr(skb)->protocol;
1432 sk->sk_bound_dev_if = arg->bound_dev_if;
1433 ip_append_data(sk, ip_reply_glue_bits, arg->iov->iov_base, len, 0,
1434 &ipc, &rt, MSG_DONTWAIT);
1435 if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
1436 if (arg->csumoffset >= 0)
1437 *((__sum16 *)skb_transport_header(skb) +
1438 arg->csumoffset) = csum_fold(csum_add(skb->csum,
1439 arg->csum));
1440 skb->ip_summed = CHECKSUM_NONE;
1441 ip_push_pending_frames(sk);
1442 }
1443
1444 bh_unlock_sock(sk);
1445
1446 ip_rt_put(rt);
1447 }
1448
1449 void __init ip_init(void)
1450 {
1451 ip_rt_init();
1452 inet_initpeers();
1453
1454 #if defined(CONFIG_IP_MULTICAST) && defined(CONFIG_PROC_FS)
1455 igmp_mc_proc_init();
1456 #endif
1457 }
Linux kernel - Deliverables
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