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