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[deliverable/linux.git] / net / ipv4 / ip_output.c
1 /*
2 * INET An implementation of the TCP/IP protocol suite for the LINUX
3 * operating system. INET is implemented using the BSD Socket
4 * interface as the means of communication with the user level.
5 *
6 * The Internet Protocol (IP) output module.
7 *
8 * Authors: Ross Biro
9 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
10 * Donald Becker, <becker@super.org>
11 * Alan Cox, <Alan.Cox@linux.org>
12 * Richard Underwood
13 * Stefan Becker, <stefanb@yello.ping.de>
14 * Jorge Cwik, <jorge@laser.satlink.net>
15 * Arnt Gulbrandsen, <agulbra@nvg.unit.no>
16 * Hirokazu Takahashi, <taka@valinux.co.jp>
17 *
18 * See ip_input.c for original log
19 *
20 * Fixes:
21 * Alan Cox : Missing nonblock feature in ip_build_xmit.
22 * Mike Kilburn : htons() missing in ip_build_xmit.
23 * Bradford Johnson: Fix faulty handling of some frames when
24 * no route is found.
25 * Alexander Demenshin: Missing sk/skb free in ip_queue_xmit
26 * (in case if packet not accepted by
27 * output firewall rules)
28 * Mike McLagan : Routing by source
29 * Alexey Kuznetsov: use new route cache
30 * Andi Kleen: Fix broken PMTU recovery and remove
31 * some redundant tests.
32 * Vitaly E. Lavrov : Transparent proxy revived after year coma.
33 * Andi Kleen : Replace ip_reply with ip_send_reply.
34 * Andi Kleen : Split fast and slow ip_build_xmit path
35 * for decreased register pressure on x86
36 * and more readibility.
37 * Marc Boucher : When call_out_firewall returns FW_QUEUE,
38 * silently drop skb instead of failing with -EPERM.
39 * Detlev Wengorz : Copy protocol for fragments.
40 * Hirokazu Takahashi: HW checksumming for outgoing UDP
41 * datagrams.
42 * Hirokazu Takahashi: sendfile() on UDP works now.
43 */
44
45 #include <asm/uaccess.h>
46 #include <linux/module.h>
47 #include <linux/types.h>
48 #include <linux/kernel.h>
49 #include <linux/mm.h>
50 #include <linux/string.h>
51 #include <linux/errno.h>
52 #include <linux/highmem.h>
53 #include <linux/slab.h>
54
55 #include <linux/socket.h>
56 #include <linux/sockios.h>
57 #include <linux/in.h>
58 #include <linux/inet.h>
59 #include <linux/netdevice.h>
60 #include <linux/etherdevice.h>
61 #include <linux/proc_fs.h>
62 #include <linux/stat.h>
63 #include <linux/init.h>
64
65 #include <net/snmp.h>
66 #include <net/ip.h>
67 #include <net/protocol.h>
68 #include <net/route.h>
69 #include <net/xfrm.h>
70 #include <linux/skbuff.h>
71 #include <net/sock.h>
72 #include <net/arp.h>
73 #include <net/icmp.h>
74 #include <net/checksum.h>
75 #include <net/inetpeer.h>
76 #include <linux/igmp.h>
77 #include <linux/netfilter_ipv4.h>
78 #include <linux/netfilter_bridge.h>
79 #include <linux/mroute.h>
80 #include <linux/netlink.h>
81 #include <linux/tcp.h>
82
83 int sysctl_ip_default_ttl __read_mostly = IPDEFTTL;
84 EXPORT_SYMBOL(sysctl_ip_default_ttl);
85
86 /* Generate a checksum for an outgoing IP datagram. */
87 void ip_send_check(struct iphdr *iph)
88 {
89 iph->check = 0;
90 iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
91 }
92 EXPORT_SYMBOL(ip_send_check);
93
94 int __ip_local_out(struct sk_buff *skb)
95 {
96 struct iphdr *iph = ip_hdr(skb);
97
98 iph->tot_len = htons(skb->len);
99 ip_send_check(iph);
100 return nf_hook(NFPROTO_IPV4, NF_INET_LOCAL_OUT, skb, NULL,
101 skb_dst(skb)->dev, dst_output);
102 }
103
104 int ip_local_out(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
450 dev = rt->dst.dev;
451
452 /*
453 * Point into the IP datagram header.
454 */
455
456 iph = ip_hdr(skb);
457
458 mtu = ip_skb_dst_mtu(skb);
459 if (unlikely(((iph->frag_off & htons(IP_DF)) && !skb->local_df) ||
460 (IPCB(skb)->frag_max_size &&
461 IPCB(skb)->frag_max_size > mtu))) {
462 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
463 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
464 htonl(mtu));
465 kfree_skb(skb);
466 return -EMSGSIZE;
467 }
468
469 /*
470 * Setup starting values.
471 */
472
473 hlen = iph->ihl * 4;
474 mtu = mtu - hlen; /* Size of data space */
475 #ifdef CONFIG_BRIDGE_NETFILTER
476 if (skb->nf_bridge)
477 mtu -= nf_bridge_mtu_reduction(skb);
478 #endif
479 IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE;
480
481 /* When frag_list is given, use it. First, check its validity:
482 * some transformers could create wrong frag_list or break existing
483 * one, it is not prohibited. In this case fall back to copying.
484 *
485 * LATER: this step can be merged to real generation of fragments,
486 * we can switch to copy when see the first bad fragment.
487 */
488 if (skb_has_frag_list(skb)) {
489 struct sk_buff *frag, *frag2;
490 int first_len = skb_pagelen(skb);
491
492 if (first_len - hlen > mtu ||
493 ((first_len - hlen) & 7) ||
494 ip_is_fragment(iph) ||
495 skb_cloned(skb))
496 goto slow_path;
497
498 skb_walk_frags(skb, frag) {
499 /* Correct geometry. */
500 if (frag->len > mtu ||
501 ((frag->len & 7) && frag->next) ||
502 skb_headroom(frag) < hlen)
503 goto slow_path_clean;
504
505 /* Partially cloned skb? */
506 if (skb_shared(frag))
507 goto slow_path_clean;
508
509 BUG_ON(frag->sk);
510 if (skb->sk) {
511 frag->sk = skb->sk;
512 frag->destructor = sock_wfree;
513 }
514 skb->truesize -= frag->truesize;
515 }
516
517 /* Everything is OK. Generate! */
518
519 err = 0;
520 offset = 0;
521 frag = skb_shinfo(skb)->frag_list;
522 skb_frag_list_init(skb);
523 skb->data_len = first_len - skb_headlen(skb);
524 skb->len = first_len;
525 iph->tot_len = htons(first_len);
526 iph->frag_off = htons(IP_MF);
527 ip_send_check(iph);
528
529 for (;;) {
530 /* Prepare header of the next frame,
531 * before previous one went down. */
532 if (frag) {
533 frag->ip_summed = CHECKSUM_NONE;
534 skb_reset_transport_header(frag);
535 __skb_push(frag, hlen);
536 skb_reset_network_header(frag);
537 memcpy(skb_network_header(frag), iph, hlen);
538 iph = ip_hdr(frag);
539 iph->tot_len = htons(frag->len);
540 ip_copy_metadata(frag, skb);
541 if (offset == 0)
542 ip_options_fragment(frag);
543 offset += skb->len - hlen;
544 iph->frag_off = htons(offset>>3);
545 if (frag->next != NULL)
546 iph->frag_off |= htons(IP_MF);
547 /* Ready, complete checksum */
548 ip_send_check(iph);
549 }
550
551 err = output(skb);
552
553 if (!err)
554 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES);
555 if (err || !frag)
556 break;
557
558 skb = frag;
559 frag = skb->next;
560 skb->next = NULL;
561 }
562
563 if (err == 0) {
564 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS);
565 return 0;
566 }
567
568 while (frag) {
569 skb = frag->next;
570 kfree_skb(frag);
571 frag = skb;
572 }
573 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
574 return err;
575
576 slow_path_clean:
577 skb_walk_frags(skb, frag2) {
578 if (frag2 == frag)
579 break;
580 frag2->sk = NULL;
581 frag2->destructor = NULL;
582 skb->truesize += frag2->truesize;
583 }
584 }
585
586 slow_path:
587 /* for offloaded checksums cleanup checksum before fragmentation */
588 if ((skb->ip_summed == CHECKSUM_PARTIAL) && skb_checksum_help(skb))
589 goto fail;
590 iph = ip_hdr(skb);
591
592 left = skb->len - hlen; /* Space per frame */
593 ptr = hlen; /* Where to start from */
594
595 /* for bridged IP traffic encapsulated inside f.e. a vlan header,
596 * we need to make room for the encapsulating header
597 */
598 ll_rs = LL_RESERVED_SPACE_EXTRA(rt->dst.dev, nf_bridge_pad(skb));
599
600 /*
601 * Fragment the datagram.
602 */
603
604 offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3;
605 not_last_frag = iph->frag_off & htons(IP_MF);
606
607 /*
608 * Keep copying data until we run out.
609 */
610
611 while (left > 0) {
612 len = left;
613 /* IF: it doesn't fit, use 'mtu' - the data space left */
614 if (len > mtu)
615 len = mtu;
616 /* IF: we are not sending up to and including the packet end
617 then align the next start on an eight byte boundary */
618 if (len < left) {
619 len &= ~7;
620 }
621 /*
622 * Allocate buffer.
623 */
624
625 if ((skb2 = alloc_skb(len+hlen+ll_rs, GFP_ATOMIC)) == NULL) {
626 NETDEBUG(KERN_INFO "IP: frag: no memory for new fragment!\n");
627 err = -ENOMEM;
628 goto fail;
629 }
630
631 /*
632 * Set up data on packet
633 */
634
635 ip_copy_metadata(skb2, skb);
636 skb_reserve(skb2, ll_rs);
637 skb_put(skb2, len + hlen);
638 skb_reset_network_header(skb2);
639 skb2->transport_header = skb2->network_header + hlen;
640
641 /*
642 * Charge the memory for the fragment to any owner
643 * it might possess
644 */
645
646 if (skb->sk)
647 skb_set_owner_w(skb2, skb->sk);
648
649 /*
650 * Copy the packet header into the new buffer.
651 */
652
653 skb_copy_from_linear_data(skb, skb_network_header(skb2), hlen);
654
655 /*
656 * Copy a block of the IP datagram.
657 */
658 if (skb_copy_bits(skb, ptr, skb_transport_header(skb2), len))
659 BUG();
660 left -= len;
661
662 /*
663 * Fill in the new header fields.
664 */
665 iph = ip_hdr(skb2);
666 iph->frag_off = htons((offset >> 3));
667
668 /* ANK: dirty, but effective trick. Upgrade options only if
669 * the segment to be fragmented was THE FIRST (otherwise,
670 * options are already fixed) and make it ONCE
671 * on the initial skb, so that all the following fragments
672 * will inherit fixed options.
673 */
674 if (offset == 0)
675 ip_options_fragment(skb);
676
677 /*
678 * Added AC : If we are fragmenting a fragment that's not the
679 * last fragment then keep MF on each bit
680 */
681 if (left > 0 || not_last_frag)
682 iph->frag_off |= htons(IP_MF);
683 ptr += len;
684 offset += len;
685
686 /*
687 * Put this fragment into the sending queue.
688 */
689 iph->tot_len = htons(len + hlen);
690
691 ip_send_check(iph);
692
693 err = output(skb2);
694 if (err)
695 goto fail;
696
697 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES);
698 }
699 consume_skb(skb);
700 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS);
701 return err;
702
703 fail:
704 kfree_skb(skb);
705 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
706 return err;
707 }
708 EXPORT_SYMBOL(ip_fragment);
709
710 int
711 ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
712 {
713 struct iovec *iov = from;
714
715 if (skb->ip_summed == CHECKSUM_PARTIAL) {
716 if (memcpy_fromiovecend(to, iov, offset, len) < 0)
717 return -EFAULT;
718 } else {
719 __wsum csum = 0;
720 if (csum_partial_copy_fromiovecend(to, iov, offset, len, &csum) < 0)
721 return -EFAULT;
722 skb->csum = csum_block_add(skb->csum, csum, odd);
723 }
724 return 0;
725 }
726 EXPORT_SYMBOL(ip_generic_getfrag);
727
728 static inline __wsum
729 csum_page(struct page *page, int offset, int copy)
730 {
731 char *kaddr;
732 __wsum csum;
733 kaddr = kmap(page);
734 csum = csum_partial(kaddr + offset, copy, 0);
735 kunmap(page);
736 return csum;
737 }
738
739 static inline int ip_ufo_append_data(struct sock *sk,
740 struct sk_buff_head *queue,
741 int getfrag(void *from, char *to, int offset, int len,
742 int odd, struct sk_buff *skb),
743 void *from, int length, int hh_len, int fragheaderlen,
744 int transhdrlen, int maxfraglen, unsigned int flags)
745 {
746 struct sk_buff *skb;
747 int err;
748
749 /* There is support for UDP fragmentation offload by network
750 * device, so create one single skb packet containing complete
751 * udp datagram
752 */
753 if ((skb = skb_peek_tail(queue)) == NULL) {
754 skb = sock_alloc_send_skb(sk,
755 hh_len + fragheaderlen + transhdrlen + 20,
756 (flags & MSG_DONTWAIT), &err);
757
758 if (skb == NULL)
759 return err;
760
761 /* reserve space for Hardware header */
762 skb_reserve(skb, hh_len);
763
764 /* create space for UDP/IP header */
765 skb_put(skb, fragheaderlen + transhdrlen);
766
767 /* initialize network header pointer */
768 skb_reset_network_header(skb);
769
770 /* initialize protocol header pointer */
771 skb->transport_header = skb->network_header + fragheaderlen;
772
773 skb->csum = 0;
774
775
776 __skb_queue_tail(queue, skb);
777 } else if (skb_is_gso(skb)) {
778 goto append;
779 }
780
781 skb->ip_summed = CHECKSUM_PARTIAL;
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
786 append:
787 return skb_append_datato_frags(sk, skb, getfrag, from,
788 (length - transhdrlen));
789 }
790
791 static int __ip_append_data(struct sock *sk,
792 struct flowi4 *fl4,
793 struct sk_buff_head *queue,
794 struct inet_cork *cork,
795 struct page_frag *pfrag,
796 int getfrag(void *from, char *to, int offset,
797 int len, int odd, struct sk_buff *skb),
798 void *from, int length, int transhdrlen,
799 unsigned int flags)
800 {
801 struct inet_sock *inet = inet_sk(sk);
802 struct sk_buff *skb;
803
804 struct ip_options *opt = cork->opt;
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, maxnonfragsize;
812 int csummode = CHECKSUM_NONE;
813 struct rtable *rt = (struct rtable *)cork->dst;
814
815 skb = skb_peek_tail(queue);
816
817 exthdrlen = !skb ? rt->dst.header_len : 0;
818 mtu = cork->fragsize;
819
820 hh_len = LL_RESERVED_SPACE(rt->dst.dev);
821
822 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
823 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
824 maxnonfragsize = ip_sk_local_df(sk) ? 0xFFFF : mtu;
825
826 if (cork->length + length > maxnonfragsize - fragheaderlen) {
827 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
828 mtu - (opt ? opt->optlen : 0));
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 ip_options_rcu *opt;
1038 struct rtable *rt;
1039
1040 /*
1041 * setup for corking.
1042 */
1043 opt = ipc->opt;
1044 if (opt) {
1045 if (cork->opt == NULL) {
1046 cork->opt = kmalloc(sizeof(struct ip_options) + 40,
1047 sk->sk_allocation);
1048 if (unlikely(cork->opt == NULL))
1049 return -ENOBUFS;
1050 }
1051 memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen);
1052 cork->flags |= IPCORK_OPT;
1053 cork->addr = ipc->addr;
1054 }
1055 rt = *rtp;
1056 if (unlikely(!rt))
1057 return -EFAULT;
1058 /*
1059 * We steal reference to this route, caller should not release it
1060 */
1061 *rtp = NULL;
1062 cork->fragsize = ip_sk_use_pmtu(sk) ?
1063 dst_mtu(&rt->dst) : rt->dst.dev->mtu;
1064 cork->dst = &rt->dst;
1065 cork->length = 0;
1066 cork->ttl = ipc->ttl;
1067 cork->tos = ipc->tos;
1068 cork->priority = ipc->priority;
1069 cork->tx_flags = ipc->tx_flags;
1070
1071 return 0;
1072 }
1073
1074 /*
1075 * ip_append_data() and ip_append_page() can make one large IP datagram
1076 * from many pieces of data. Each pieces will be holded on the socket
1077 * until ip_push_pending_frames() is called. Each piece can be a page
1078 * or non-page data.
1079 *
1080 * Not only UDP, other transport protocols - e.g. raw sockets - can use
1081 * this interface potentially.
1082 *
1083 * LATER: length must be adjusted by pad at tail, when it is required.
1084 */
1085 int ip_append_data(struct sock *sk, struct flowi4 *fl4,
1086 int getfrag(void *from, char *to, int offset, int len,
1087 int odd, struct sk_buff *skb),
1088 void *from, int length, int transhdrlen,
1089 struct ipcm_cookie *ipc, struct rtable **rtp,
1090 unsigned int flags)
1091 {
1092 struct inet_sock *inet = inet_sk(sk);
1093 int err;
1094
1095 if (flags&MSG_PROBE)
1096 return 0;
1097
1098 if (skb_queue_empty(&sk->sk_write_queue)) {
1099 err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp);
1100 if (err)
1101 return err;
1102 } else {
1103 transhdrlen = 0;
1104 }
1105
1106 return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base,
1107 sk_page_frag(sk), getfrag,
1108 from, length, transhdrlen, flags);
1109 }
1110
1111 ssize_t ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page,
1112 int offset, size_t size, int flags)
1113 {
1114 struct inet_sock *inet = inet_sk(sk);
1115 struct sk_buff *skb;
1116 struct rtable *rt;
1117 struct ip_options *opt = NULL;
1118 struct inet_cork *cork;
1119 int hh_len;
1120 int mtu;
1121 int len;
1122 int err;
1123 unsigned int maxfraglen, fragheaderlen, fraggap, maxnonfragsize;
1124
1125 if (inet->hdrincl)
1126 return -EPERM;
1127
1128 if (flags&MSG_PROBE)
1129 return 0;
1130
1131 if (skb_queue_empty(&sk->sk_write_queue))
1132 return -EINVAL;
1133
1134 cork = &inet->cork.base;
1135 rt = (struct rtable *)cork->dst;
1136 if (cork->flags & IPCORK_OPT)
1137 opt = cork->opt;
1138
1139 if (!(rt->dst.dev->features&NETIF_F_SG))
1140 return -EOPNOTSUPP;
1141
1142 hh_len = LL_RESERVED_SPACE(rt->dst.dev);
1143 mtu = cork->fragsize;
1144
1145 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
1146 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
1147 maxnonfragsize = ip_sk_local_df(sk) ? 0xFFFF : mtu;
1148
1149 if (cork->length + size > maxnonfragsize - fragheaderlen) {
1150 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
1151 mtu - (opt ? opt->optlen : 0));
1152 return -EMSGSIZE;
1153 }
1154
1155 if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL)
1156 return -EINVAL;
1157
1158 cork->length += size;
1159 if ((size + skb->len > mtu) &&
1160 (sk->sk_protocol == IPPROTO_UDP) &&
1161 (rt->dst.dev->features & NETIF_F_UFO)) {
1162 skb_shinfo(skb)->gso_size = mtu - fragheaderlen;
1163 skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
1164 }
1165
1166
1167 while (size > 0) {
1168 int i;
1169
1170 if (skb_is_gso(skb))
1171 len = size;
1172 else {
1173
1174 /* Check if the remaining data fits into current packet. */
1175 len = mtu - skb->len;
1176 if (len < size)
1177 len = maxfraglen - skb->len;
1178 }
1179 if (len <= 0) {
1180 struct sk_buff *skb_prev;
1181 int alloclen;
1182
1183 skb_prev = skb;
1184 fraggap = skb_prev->len - maxfraglen;
1185
1186 alloclen = fragheaderlen + hh_len + fraggap + 15;
1187 skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation);
1188 if (unlikely(!skb)) {
1189 err = -ENOBUFS;
1190 goto error;
1191 }
1192
1193 /*
1194 * Fill in the control structures
1195 */
1196 skb->ip_summed = CHECKSUM_NONE;
1197 skb->csum = 0;
1198 skb_reserve(skb, hh_len);
1199
1200 /*
1201 * Find where to start putting bytes.
1202 */
1203 skb_put(skb, fragheaderlen + fraggap);
1204 skb_reset_network_header(skb);
1205 skb->transport_header = (skb->network_header +
1206 fragheaderlen);
1207 if (fraggap) {
1208 skb->csum = skb_copy_and_csum_bits(skb_prev,
1209 maxfraglen,
1210 skb_transport_header(skb),
1211 fraggap, 0);
1212 skb_prev->csum = csum_sub(skb_prev->csum,
1213 skb->csum);
1214 pskb_trim_unique(skb_prev, maxfraglen);
1215 }
1216
1217 /*
1218 * Put the packet on the pending queue.
1219 */
1220 __skb_queue_tail(&sk->sk_write_queue, skb);
1221 continue;
1222 }
1223
1224 i = skb_shinfo(skb)->nr_frags;
1225 if (len > size)
1226 len = size;
1227 if (skb_can_coalesce(skb, i, page, offset)) {
1228 skb_frag_size_add(&skb_shinfo(skb)->frags[i-1], len);
1229 } else if (i < MAX_SKB_FRAGS) {
1230 get_page(page);
1231 skb_fill_page_desc(skb, i, page, offset, len);
1232 } else {
1233 err = -EMSGSIZE;
1234 goto error;
1235 }
1236
1237 if (skb->ip_summed == CHECKSUM_NONE) {
1238 __wsum csum;
1239 csum = csum_page(page, offset, len);
1240 skb->csum = csum_block_add(skb->csum, csum, skb->len);
1241 }
1242
1243 skb->len += len;
1244 skb->data_len += len;
1245 skb->truesize += len;
1246 atomic_add(len, &sk->sk_wmem_alloc);
1247 offset += len;
1248 size -= len;
1249 }
1250 return 0;
1251
1252 error:
1253 cork->length -= size;
1254 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1255 return err;
1256 }
1257
1258 static void ip_cork_release(struct inet_cork *cork)
1259 {
1260 cork->flags &= ~IPCORK_OPT;
1261 kfree(cork->opt);
1262 cork->opt = NULL;
1263 dst_release(cork->dst);
1264 cork->dst = NULL;
1265 }
1266
1267 /*
1268 * Combined all pending IP fragments on the socket as one IP datagram
1269 * and push them out.
1270 */
1271 struct sk_buff *__ip_make_skb(struct sock *sk,
1272 struct flowi4 *fl4,
1273 struct sk_buff_head *queue,
1274 struct inet_cork *cork)
1275 {
1276 struct sk_buff *skb, *tmp_skb;
1277 struct sk_buff **tail_skb;
1278 struct inet_sock *inet = inet_sk(sk);
1279 struct net *net = sock_net(sk);
1280 struct ip_options *opt = NULL;
1281 struct rtable *rt = (struct rtable *)cork->dst;
1282 struct iphdr *iph;
1283 __be16 df = 0;
1284 __u8 ttl;
1285
1286 if ((skb = __skb_dequeue(queue)) == NULL)
1287 goto out;
1288 tail_skb = &(skb_shinfo(skb)->frag_list);
1289
1290 /* move skb->data to ip header from ext header */
1291 if (skb->data < skb_network_header(skb))
1292 __skb_pull(skb, skb_network_offset(skb));
1293 while ((tmp_skb = __skb_dequeue(queue)) != NULL) {
1294 __skb_pull(tmp_skb, skb_network_header_len(skb));
1295 *tail_skb = tmp_skb;
1296 tail_skb = &(tmp_skb->next);
1297 skb->len += tmp_skb->len;
1298 skb->data_len += tmp_skb->len;
1299 skb->truesize += tmp_skb->truesize;
1300 tmp_skb->destructor = NULL;
1301 tmp_skb->sk = NULL;
1302 }
1303
1304 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow
1305 * to fragment the frame generated here. No matter, what transforms
1306 * how transforms change size of the packet, it will come out.
1307 */
1308 skb->local_df = ip_sk_local_df(sk);
1309
1310 /* DF bit is set when we want to see DF on outgoing frames.
1311 * If local_df is set too, we still allow to fragment this frame
1312 * locally. */
1313 if (inet->pmtudisc == IP_PMTUDISC_DO ||
1314 inet->pmtudisc == IP_PMTUDISC_PROBE ||
1315 (skb->len <= dst_mtu(&rt->dst) &&
1316 ip_dont_fragment(sk, &rt->dst)))
1317 df = htons(IP_DF);
1318
1319 if (cork->flags & IPCORK_OPT)
1320 opt = cork->opt;
1321
1322 if (cork->ttl != 0)
1323 ttl = cork->ttl;
1324 else if (rt->rt_type == RTN_MULTICAST)
1325 ttl = inet->mc_ttl;
1326 else
1327 ttl = ip_select_ttl(inet, &rt->dst);
1328
1329 iph = ip_hdr(skb);
1330 iph->version = 4;
1331 iph->ihl = 5;
1332 iph->tos = (cork->tos != -1) ? cork->tos : inet->tos;
1333 iph->frag_off = df;
1334 iph->ttl = ttl;
1335 iph->protocol = sk->sk_protocol;
1336 ip_copy_addrs(iph, fl4);
1337 ip_select_ident(skb, &rt->dst, sk);
1338
1339 if (opt) {
1340 iph->ihl += opt->optlen>>2;
1341 ip_options_build(skb, opt, cork->addr, rt, 0);
1342 }
1343
1344 skb->priority = (cork->tos != -1) ? cork->priority: sk->sk_priority;
1345 skb->mark = sk->sk_mark;
1346 /*
1347 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec
1348 * on dst refcount
1349 */
1350 cork->dst = NULL;
1351 skb_dst_set(skb, &rt->dst);
1352
1353 if (iph->protocol == IPPROTO_ICMP)
1354 icmp_out_count(net, ((struct icmphdr *)
1355 skb_transport_header(skb))->type);
1356
1357 ip_cork_release(cork);
1358 out:
1359 return skb;
1360 }
1361
1362 int ip_send_skb(struct net *net, struct sk_buff *skb)
1363 {
1364 int err;
1365
1366 err = ip_local_out(skb);
1367 if (err) {
1368 if (err > 0)
1369 err = net_xmit_errno(err);
1370 if (err)
1371 IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS);
1372 }
1373
1374 return err;
1375 }
1376
1377 int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4)
1378 {
1379 struct sk_buff *skb;
1380
1381 skb = ip_finish_skb(sk, fl4);
1382 if (!skb)
1383 return 0;
1384
1385 /* Netfilter gets whole the not fragmented skb. */
1386 return ip_send_skb(sock_net(sk), skb);
1387 }
1388
1389 /*
1390 * Throw away all pending data on the socket.
1391 */
1392 static void __ip_flush_pending_frames(struct sock *sk,
1393 struct sk_buff_head *queue,
1394 struct inet_cork *cork)
1395 {
1396 struct sk_buff *skb;
1397
1398 while ((skb = __skb_dequeue_tail(queue)) != NULL)
1399 kfree_skb(skb);
1400
1401 ip_cork_release(cork);
1402 }
1403
1404 void ip_flush_pending_frames(struct sock *sk)
1405 {
1406 __ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork.base);
1407 }
1408
1409 struct sk_buff *ip_make_skb(struct sock *sk,
1410 struct flowi4 *fl4,
1411 int getfrag(void *from, char *to, int offset,
1412 int len, int odd, struct sk_buff *skb),
1413 void *from, int length, int transhdrlen,
1414 struct ipcm_cookie *ipc, struct rtable **rtp,
1415 unsigned int flags)
1416 {
1417 struct inet_cork cork;
1418 struct sk_buff_head queue;
1419 int err;
1420
1421 if (flags & MSG_PROBE)
1422 return NULL;
1423
1424 __skb_queue_head_init(&queue);
1425
1426 cork.flags = 0;
1427 cork.addr = 0;
1428 cork.opt = NULL;
1429 err = ip_setup_cork(sk, &cork, ipc, rtp);
1430 if (err)
1431 return ERR_PTR(err);
1432
1433 err = __ip_append_data(sk, fl4, &queue, &cork,
1434 &current->task_frag, getfrag,
1435 from, length, transhdrlen, flags);
1436 if (err) {
1437 __ip_flush_pending_frames(sk, &queue, &cork);
1438 return ERR_PTR(err);
1439 }
1440
1441 return __ip_make_skb(sk, fl4, &queue, &cork);
1442 }
1443
1444 /*
1445 * Fetch data from kernel space and fill in checksum if needed.
1446 */
1447 static int ip_reply_glue_bits(void *dptr, char *to, int offset,
1448 int len, int odd, struct sk_buff *skb)
1449 {
1450 __wsum csum;
1451
1452 csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0);
1453 skb->csum = csum_block_add(skb->csum, csum, odd);
1454 return 0;
1455 }
1456
1457 /*
1458 * Generic function to send a packet as reply to another packet.
1459 * Used to send some TCP resets/acks so far.
1460 *
1461 * Use a fake percpu inet socket to avoid false sharing and contention.
1462 */
1463 static DEFINE_PER_CPU(struct inet_sock, unicast_sock) = {
1464 .sk = {
1465 .__sk_common = {
1466 .skc_refcnt = ATOMIC_INIT(1),
1467 },
1468 .sk_wmem_alloc = ATOMIC_INIT(1),
1469 .sk_allocation = GFP_ATOMIC,
1470 .sk_flags = (1UL << SOCK_USE_WRITE_QUEUE),
1471 },
1472 .pmtudisc = IP_PMTUDISC_WANT,
1473 .uc_ttl = -1,
1474 };
1475
1476 void ip_send_unicast_reply(struct net *net, struct sk_buff *skb, __be32 daddr,
1477 __be32 saddr, const struct ip_reply_arg *arg,
1478 unsigned int len)
1479 {
1480 struct ip_options_data replyopts;
1481 struct ipcm_cookie ipc;
1482 struct flowi4 fl4;
1483 struct rtable *rt = skb_rtable(skb);
1484 struct sk_buff *nskb;
1485 struct sock *sk;
1486 struct inet_sock *inet;
1487
1488 if (ip_options_echo(&replyopts.opt.opt, skb))
1489 return;
1490
1491 ipc.addr = daddr;
1492 ipc.opt = NULL;
1493 ipc.tx_flags = 0;
1494 ipc.ttl = 0;
1495 ipc.tos = -1;
1496
1497 if (replyopts.opt.opt.optlen) {
1498 ipc.opt = &replyopts.opt;
1499
1500 if (replyopts.opt.opt.srr)
1501 daddr = replyopts.opt.opt.faddr;
1502 }
1503
1504 flowi4_init_output(&fl4, arg->bound_dev_if, 0,
1505 RT_TOS(arg->tos),
1506 RT_SCOPE_UNIVERSE, ip_hdr(skb)->protocol,
1507 ip_reply_arg_flowi_flags(arg),
1508 daddr, saddr,
1509 tcp_hdr(skb)->source, tcp_hdr(skb)->dest);
1510 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
1511 rt = ip_route_output_key(net, &fl4);
1512 if (IS_ERR(rt))
1513 return;
1514
1515 inet = &get_cpu_var(unicast_sock);
1516
1517 inet->tos = arg->tos;
1518 sk = &inet->sk;
1519 sk->sk_priority = skb->priority;
1520 sk->sk_protocol = ip_hdr(skb)->protocol;
1521 sk->sk_bound_dev_if = arg->bound_dev_if;
1522 sock_net_set(sk, net);
1523 __skb_queue_head_init(&sk->sk_write_queue);
1524 sk->sk_sndbuf = sysctl_wmem_default;
1525 ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base, len, 0,
1526 &ipc, &rt, MSG_DONTWAIT);
1527 nskb = skb_peek(&sk->sk_write_queue);
1528 if (nskb) {
1529 if (arg->csumoffset >= 0)
1530 *((__sum16 *)skb_transport_header(nskb) +
1531 arg->csumoffset) = csum_fold(csum_add(nskb->csum,
1532 arg->csum));
1533 nskb->ip_summed = CHECKSUM_NONE;
1534 skb_orphan(nskb);
1535 skb_set_queue_mapping(nskb, skb_get_queue_mapping(skb));
1536 ip_push_pending_frames(sk, &fl4);
1537 }
1538
1539 put_cpu_var(unicast_sock);
1540
1541 ip_rt_put(rt);
1542 }
1543
1544 void __init ip_init(void)
1545 {
1546 ip_rt_init();
1547 inet_initpeers();
1548
1549 #if defined(CONFIG_IP_MULTICAST)
1550 igmp_mc_init();
1551 #endif
1552 }
Linux kernel - Deliverables
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