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