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Merge remote-tracking branch 'regulator/topic/da9063' into regulator-next
[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 IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TRACE)
426 to->nf_trace = from->nf_trace;
427 #endif
428 #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
429 to->ipvs_property = from->ipvs_property;
430 #endif
431 skb_copy_secmark(to, from);
432 }
433
434 /*
435 * This IP datagram is too large to be sent in one piece. Break it up into
436 * smaller pieces (each of size equal to IP header plus
437 * a block of the data of the original IP data part) that will yet fit in a
438 * single device frame, and queue such a frame for sending.
439 */
440
441 int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *))
442 {
443 struct iphdr *iph;
444 int ptr;
445 struct net_device *dev;
446 struct sk_buff *skb2;
447 unsigned int mtu, hlen, left, len, ll_rs;
448 int offset;
449 __be16 not_last_frag;
450 struct rtable *rt = skb_rtable(skb);
451 int err = 0;
452
453 dev = rt->dst.dev;
454
455 /*
456 * Point into the IP datagram header.
457 */
458
459 iph = ip_hdr(skb);
460
461 if (unlikely(((iph->frag_off & htons(IP_DF)) && !skb->local_df) ||
462 (IPCB(skb)->frag_max_size &&
463 IPCB(skb)->frag_max_size > dst_mtu(&rt->dst)))) {
464 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
465 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
466 htonl(ip_skb_dst_mtu(skb)));
467 kfree_skb(skb);
468 return -EMSGSIZE;
469 }
470
471 /*
472 * Setup starting values.
473 */
474
475 hlen = iph->ihl * 4;
476 mtu = dst_mtu(&rt->dst) - hlen; /* Size of data space */
477 #ifdef CONFIG_BRIDGE_NETFILTER
478 if (skb->nf_bridge)
479 mtu -= nf_bridge_mtu_reduction(skb);
480 #endif
481 IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE;
482
483 /* When frag_list is given, use it. First, check its validity:
484 * some transformers could create wrong frag_list or break existing
485 * one, it is not prohibited. In this case fall back to copying.
486 *
487 * LATER: this step can be merged to real generation of fragments,
488 * we can switch to copy when see the first bad fragment.
489 */
490 if (skb_has_frag_list(skb)) {
491 struct sk_buff *frag, *frag2;
492 int first_len = skb_pagelen(skb);
493
494 if (first_len - hlen > mtu ||
495 ((first_len - hlen) & 7) ||
496 ip_is_fragment(iph) ||
497 skb_cloned(skb))
498 goto slow_path;
499
500 skb_walk_frags(skb, frag) {
501 /* Correct geometry. */
502 if (frag->len > mtu ||
503 ((frag->len & 7) && frag->next) ||
504 skb_headroom(frag) < hlen)
505 goto slow_path_clean;
506
507 /* Partially cloned skb? */
508 if (skb_shared(frag))
509 goto slow_path_clean;
510
511 BUG_ON(frag->sk);
512 if (skb->sk) {
513 frag->sk = skb->sk;
514 frag->destructor = sock_wfree;
515 }
516 skb->truesize -= frag->truesize;
517 }
518
519 /* Everything is OK. Generate! */
520
521 err = 0;
522 offset = 0;
523 frag = skb_shinfo(skb)->frag_list;
524 skb_frag_list_init(skb);
525 skb->data_len = first_len - skb_headlen(skb);
526 skb->len = first_len;
527 iph->tot_len = htons(first_len);
528 iph->frag_off = htons(IP_MF);
529 ip_send_check(iph);
530
531 for (;;) {
532 /* Prepare header of the next frame,
533 * before previous one went down. */
534 if (frag) {
535 frag->ip_summed = CHECKSUM_NONE;
536 skb_reset_transport_header(frag);
537 __skb_push(frag, hlen);
538 skb_reset_network_header(frag);
539 memcpy(skb_network_header(frag), iph, hlen);
540 iph = ip_hdr(frag);
541 iph->tot_len = htons(frag->len);
542 ip_copy_metadata(frag, skb);
543 if (offset == 0)
544 ip_options_fragment(frag);
545 offset += skb->len - hlen;
546 iph->frag_off = htons(offset>>3);
547 if (frag->next != NULL)
548 iph->frag_off |= htons(IP_MF);
549 /* Ready, complete checksum */
550 ip_send_check(iph);
551 }
552
553 err = output(skb);
554
555 if (!err)
556 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES);
557 if (err || !frag)
558 break;
559
560 skb = frag;
561 frag = skb->next;
562 skb->next = NULL;
563 }
564
565 if (err == 0) {
566 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS);
567 return 0;
568 }
569
570 while (frag) {
571 skb = frag->next;
572 kfree_skb(frag);
573 frag = skb;
574 }
575 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
576 return err;
577
578 slow_path_clean:
579 skb_walk_frags(skb, frag2) {
580 if (frag2 == frag)
581 break;
582 frag2->sk = NULL;
583 frag2->destructor = NULL;
584 skb->truesize += frag2->truesize;
585 }
586 }
587
588 slow_path:
589 /* for offloaded checksums cleanup checksum before fragmentation */
590 if ((skb->ip_summed == CHECKSUM_PARTIAL) && skb_checksum_help(skb))
591 goto fail;
592 iph = ip_hdr(skb);
593
594 left = skb->len - hlen; /* Space per frame */
595 ptr = hlen; /* Where to start from */
596
597 /* for bridged IP traffic encapsulated inside f.e. a vlan header,
598 * we need to make room for the encapsulating header
599 */
600 ll_rs = LL_RESERVED_SPACE_EXTRA(rt->dst.dev, nf_bridge_pad(skb));
601
602 /*
603 * Fragment the datagram.
604 */
605
606 offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3;
607 not_last_frag = iph->frag_off & htons(IP_MF);
608
609 /*
610 * Keep copying data until we run out.
611 */
612
613 while (left > 0) {
614 len = left;
615 /* IF: it doesn't fit, use 'mtu' - the data space left */
616 if (len > mtu)
617 len = mtu;
618 /* IF: we are not sending up to and including the packet end
619 then align the next start on an eight byte boundary */
620 if (len < left) {
621 len &= ~7;
622 }
623 /*
624 * Allocate buffer.
625 */
626
627 if ((skb2 = alloc_skb(len+hlen+ll_rs, GFP_ATOMIC)) == NULL) {
628 NETDEBUG(KERN_INFO "IP: frag: no memory for new fragment!\n");
629 err = -ENOMEM;
630 goto fail;
631 }
632
633 /*
634 * Set up data on packet
635 */
636
637 ip_copy_metadata(skb2, skb);
638 skb_reserve(skb2, ll_rs);
639 skb_put(skb2, len + hlen);
640 skb_reset_network_header(skb2);
641 skb2->transport_header = skb2->network_header + hlen;
642
643 /*
644 * Charge the memory for the fragment to any owner
645 * it might possess
646 */
647
648 if (skb->sk)
649 skb_set_owner_w(skb2, skb->sk);
650
651 /*
652 * Copy the packet header into the new buffer.
653 */
654
655 skb_copy_from_linear_data(skb, skb_network_header(skb2), hlen);
656
657 /*
658 * Copy a block of the IP datagram.
659 */
660 if (skb_copy_bits(skb, ptr, skb_transport_header(skb2), len))
661 BUG();
662 left -= len;
663
664 /*
665 * Fill in the new header fields.
666 */
667 iph = ip_hdr(skb2);
668 iph->frag_off = htons((offset >> 3));
669
670 /* ANK: dirty, but effective trick. Upgrade options only if
671 * the segment to be fragmented was THE FIRST (otherwise,
672 * options are already fixed) and make it ONCE
673 * on the initial skb, so that all the following fragments
674 * will inherit fixed options.
675 */
676 if (offset == 0)
677 ip_options_fragment(skb);
678
679 /*
680 * Added AC : If we are fragmenting a fragment that's not the
681 * last fragment then keep MF on each bit
682 */
683 if (left > 0 || not_last_frag)
684 iph->frag_off |= htons(IP_MF);
685 ptr += len;
686 offset += len;
687
688 /*
689 * Put this fragment into the sending queue.
690 */
691 iph->tot_len = htons(len + hlen);
692
693 ip_send_check(iph);
694
695 err = output(skb2);
696 if (err)
697 goto fail;
698
699 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES);
700 }
701 consume_skb(skb);
702 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS);
703 return err;
704
705 fail:
706 kfree_skb(skb);
707 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
708 return err;
709 }
710 EXPORT_SYMBOL(ip_fragment);
711
712 int
713 ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
714 {
715 struct iovec *iov = from;
716
717 if (skb->ip_summed == CHECKSUM_PARTIAL) {
718 if (memcpy_fromiovecend(to, iov, offset, len) < 0)
719 return -EFAULT;
720 } else {
721 __wsum csum = 0;
722 if (csum_partial_copy_fromiovecend(to, iov, offset, len, &csum) < 0)
723 return -EFAULT;
724 skb->csum = csum_block_add(skb->csum, csum, odd);
725 }
726 return 0;
727 }
728 EXPORT_SYMBOL(ip_generic_getfrag);
729
730 static inline __wsum
731 csum_page(struct page *page, int offset, int copy)
732 {
733 char *kaddr;
734 __wsum csum;
735 kaddr = kmap(page);
736 csum = csum_partial(kaddr + offset, copy, 0);
737 kunmap(page);
738 return csum;
739 }
740
741 static inline int ip_ufo_append_data(struct sock *sk,
742 struct sk_buff_head *queue,
743 int getfrag(void *from, char *to, int offset, int len,
744 int odd, struct sk_buff *skb),
745 void *from, int length, int hh_len, int fragheaderlen,
746 int transhdrlen, int maxfraglen, unsigned int flags)
747 {
748 struct sk_buff *skb;
749 int err;
750
751 /* There is support for UDP fragmentation offload by network
752 * device, so create one single skb packet containing complete
753 * udp datagram
754 */
755 if ((skb = skb_peek_tail(queue)) == NULL) {
756 skb = sock_alloc_send_skb(sk,
757 hh_len + fragheaderlen + transhdrlen + 20,
758 (flags & MSG_DONTWAIT), &err);
759
760 if (skb == NULL)
761 return err;
762
763 /* reserve space for Hardware header */
764 skb_reserve(skb, hh_len);
765
766 /* create space for UDP/IP header */
767 skb_put(skb, fragheaderlen + transhdrlen);
768
769 /* initialize network header pointer */
770 skb_reset_network_header(skb);
771
772 /* initialize protocol header pointer */
773 skb->transport_header = skb->network_header + fragheaderlen;
774
775 skb->ip_summed = CHECKSUM_PARTIAL;
776 skb->csum = 0;
777
778 /* specify the length of each IP datagram fragment */
779 skb_shinfo(skb)->gso_size = maxfraglen - fragheaderlen;
780 skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
781 __skb_queue_tail(queue, skb);
782 }
783
784 return skb_append_datato_frags(sk, skb, getfrag, from,
785 (length - transhdrlen));
786 }
787
788 static int __ip_append_data(struct sock *sk,
789 struct flowi4 *fl4,
790 struct sk_buff_head *queue,
791 struct inet_cork *cork,
792 struct page_frag *pfrag,
793 int getfrag(void *from, char *to, int offset,
794 int len, int odd, struct sk_buff *skb),
795 void *from, int length, int transhdrlen,
796 unsigned int flags)
797 {
798 struct inet_sock *inet = inet_sk(sk);
799 struct sk_buff *skb;
800
801 struct ip_options *opt = cork->opt;
802 int hh_len;
803 int exthdrlen;
804 int mtu;
805 int copy;
806 int err;
807 int offset = 0;
808 unsigned int maxfraglen, fragheaderlen;
809 int csummode = CHECKSUM_NONE;
810 struct rtable *rt = (struct rtable *)cork->dst;
811
812 skb = skb_peek_tail(queue);
813
814 exthdrlen = !skb ? rt->dst.header_len : 0;
815 mtu = cork->fragsize;
816
817 hh_len = LL_RESERVED_SPACE(rt->dst.dev);
818
819 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
820 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
821
822 if (cork->length + length > 0xFFFF - fragheaderlen) {
823 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
824 mtu-exthdrlen);
825 return -EMSGSIZE;
826 }
827
828 /*
829 * transhdrlen > 0 means that this is the first fragment and we wish
830 * it won't be fragmented in the future.
831 */
832 if (transhdrlen &&
833 length + fragheaderlen <= mtu &&
834 rt->dst.dev->features & NETIF_F_V4_CSUM &&
835 !exthdrlen)
836 csummode = CHECKSUM_PARTIAL;
837
838 cork->length += length;
839 if (((length > mtu) || (skb && skb_is_gso(skb))) &&
840 (sk->sk_protocol == IPPROTO_UDP) &&
841 (rt->dst.dev->features & NETIF_F_UFO) && !rt->dst.header_len) {
842 err = ip_ufo_append_data(sk, queue, getfrag, from, length,
843 hh_len, fragheaderlen, transhdrlen,
844 maxfraglen, flags);
845 if (err)
846 goto error;
847 return 0;
848 }
849
850 /* So, what's going on in the loop below?
851 *
852 * We use calculated fragment length to generate chained skb,
853 * each of segments is IP fragment ready for sending to network after
854 * adding appropriate IP header.
855 */
856
857 if (!skb)
858 goto alloc_new_skb;
859
860 while (length > 0) {
861 /* Check if the remaining data fits into current packet. */
862 copy = mtu - skb->len;
863 if (copy < length)
864 copy = maxfraglen - skb->len;
865 if (copy <= 0) {
866 char *data;
867 unsigned int datalen;
868 unsigned int fraglen;
869 unsigned int fraggap;
870 unsigned int alloclen;
871 struct sk_buff *skb_prev;
872 alloc_new_skb:
873 skb_prev = skb;
874 if (skb_prev)
875 fraggap = skb_prev->len - maxfraglen;
876 else
877 fraggap = 0;
878
879 /*
880 * If remaining data exceeds the mtu,
881 * we know we need more fragment(s).
882 */
883 datalen = length + fraggap;
884 if (datalen > mtu - fragheaderlen)
885 datalen = maxfraglen - fragheaderlen;
886 fraglen = datalen + fragheaderlen;
887
888 if ((flags & MSG_MORE) &&
889 !(rt->dst.dev->features&NETIF_F_SG))
890 alloclen = mtu;
891 else
892 alloclen = fraglen;
893
894 alloclen += exthdrlen;
895
896 /* The last fragment gets additional space at tail.
897 * Note, with MSG_MORE we overallocate on fragments,
898 * because we have no idea what fragment will be
899 * the last.
900 */
901 if (datalen == length + fraggap)
902 alloclen += rt->dst.trailer_len;
903
904 if (transhdrlen) {
905 skb = sock_alloc_send_skb(sk,
906 alloclen + hh_len + 15,
907 (flags & MSG_DONTWAIT), &err);
908 } else {
909 skb = NULL;
910 if (atomic_read(&sk->sk_wmem_alloc) <=
911 2 * sk->sk_sndbuf)
912 skb = sock_wmalloc(sk,
913 alloclen + hh_len + 15, 1,
914 sk->sk_allocation);
915 if (unlikely(skb == NULL))
916 err = -ENOBUFS;
917 else
918 /* only the initial fragment is
919 time stamped */
920 cork->tx_flags = 0;
921 }
922 if (skb == NULL)
923 goto error;
924
925 /*
926 * Fill in the control structures
927 */
928 skb->ip_summed = csummode;
929 skb->csum = 0;
930 skb_reserve(skb, hh_len);
931 skb_shinfo(skb)->tx_flags = cork->tx_flags;
932
933 /*
934 * Find where to start putting bytes.
935 */
936 data = skb_put(skb, fraglen + exthdrlen);
937 skb_set_network_header(skb, exthdrlen);
938 skb->transport_header = (skb->network_header +
939 fragheaderlen);
940 data += fragheaderlen + exthdrlen;
941
942 if (fraggap) {
943 skb->csum = skb_copy_and_csum_bits(
944 skb_prev, maxfraglen,
945 data + transhdrlen, fraggap, 0);
946 skb_prev->csum = csum_sub(skb_prev->csum,
947 skb->csum);
948 data += fraggap;
949 pskb_trim_unique(skb_prev, maxfraglen);
950 }
951
952 copy = datalen - transhdrlen - fraggap;
953 if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) {
954 err = -EFAULT;
955 kfree_skb(skb);
956 goto error;
957 }
958
959 offset += copy;
960 length -= datalen - fraggap;
961 transhdrlen = 0;
962 exthdrlen = 0;
963 csummode = CHECKSUM_NONE;
964
965 /*
966 * Put the packet on the pending queue.
967 */
968 __skb_queue_tail(queue, skb);
969 continue;
970 }
971
972 if (copy > length)
973 copy = length;
974
975 if (!(rt->dst.dev->features&NETIF_F_SG)) {
976 unsigned int off;
977
978 off = skb->len;
979 if (getfrag(from, skb_put(skb, copy),
980 offset, copy, off, skb) < 0) {
981 __skb_trim(skb, off);
982 err = -EFAULT;
983 goto error;
984 }
985 } else {
986 int i = skb_shinfo(skb)->nr_frags;
987
988 err = -ENOMEM;
989 if (!sk_page_frag_refill(sk, pfrag))
990 goto error;
991
992 if (!skb_can_coalesce(skb, i, pfrag->page,
993 pfrag->offset)) {
994 err = -EMSGSIZE;
995 if (i == MAX_SKB_FRAGS)
996 goto error;
997
998 __skb_fill_page_desc(skb, i, pfrag->page,
999 pfrag->offset, 0);
1000 skb_shinfo(skb)->nr_frags = ++i;
1001 get_page(pfrag->page);
1002 }
1003 copy = min_t(int, copy, pfrag->size - pfrag->offset);
1004 if (getfrag(from,
1005 page_address(pfrag->page) + pfrag->offset,
1006 offset, copy, skb->len, skb) < 0)
1007 goto error_efault;
1008
1009 pfrag->offset += copy;
1010 skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
1011 skb->len += copy;
1012 skb->data_len += copy;
1013 skb->truesize += copy;
1014 atomic_add(copy, &sk->sk_wmem_alloc);
1015 }
1016 offset += copy;
1017 length -= copy;
1018 }
1019
1020 return 0;
1021
1022 error_efault:
1023 err = -EFAULT;
1024 error:
1025 cork->length -= length;
1026 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1027 return err;
1028 }
1029
1030 static int ip_setup_cork(struct sock *sk, struct inet_cork *cork,
1031 struct ipcm_cookie *ipc, struct rtable **rtp)
1032 {
1033 struct inet_sock *inet = inet_sk(sk);
1034 struct ip_options_rcu *opt;
1035 struct rtable *rt;
1036
1037 /*
1038 * setup for corking.
1039 */
1040 opt = ipc->opt;
1041 if (opt) {
1042 if (cork->opt == NULL) {
1043 cork->opt = kmalloc(sizeof(struct ip_options) + 40,
1044 sk->sk_allocation);
1045 if (unlikely(cork->opt == NULL))
1046 return -ENOBUFS;
1047 }
1048 memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen);
1049 cork->flags |= IPCORK_OPT;
1050 cork->addr = ipc->addr;
1051 }
1052 rt = *rtp;
1053 if (unlikely(!rt))
1054 return -EFAULT;
1055 /*
1056 * We steal reference to this route, caller should not release it
1057 */
1058 *rtp = NULL;
1059 cork->fragsize = inet->pmtudisc == IP_PMTUDISC_PROBE ?
1060 rt->dst.dev->mtu : dst_mtu(&rt->dst);
1061 cork->dst = &rt->dst;
1062 cork->length = 0;
1063 cork->tx_flags = ipc->tx_flags;
1064
1065 return 0;
1066 }
1067
1068 /*
1069 * ip_append_data() and ip_append_page() can make one large IP datagram
1070 * from many pieces of data. Each pieces will be holded on the socket
1071 * until ip_push_pending_frames() is called. Each piece can be a page
1072 * or non-page data.
1073 *
1074 * Not only UDP, other transport protocols - e.g. raw sockets - can use
1075 * this interface potentially.
1076 *
1077 * LATER: length must be adjusted by pad at tail, when it is required.
1078 */
1079 int ip_append_data(struct sock *sk, struct flowi4 *fl4,
1080 int getfrag(void *from, char *to, int offset, int len,
1081 int odd, struct sk_buff *skb),
1082 void *from, int length, int transhdrlen,
1083 struct ipcm_cookie *ipc, struct rtable **rtp,
1084 unsigned int flags)
1085 {
1086 struct inet_sock *inet = inet_sk(sk);
1087 int err;
1088
1089 if (flags&MSG_PROBE)
1090 return 0;
1091
1092 if (skb_queue_empty(&sk->sk_write_queue)) {
1093 err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp);
1094 if (err)
1095 return err;
1096 } else {
1097 transhdrlen = 0;
1098 }
1099
1100 return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base,
1101 sk_page_frag(sk), getfrag,
1102 from, length, transhdrlen, flags);
1103 }
1104
1105 ssize_t ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page,
1106 int offset, size_t size, int flags)
1107 {
1108 struct inet_sock *inet = inet_sk(sk);
1109 struct sk_buff *skb;
1110 struct rtable *rt;
1111 struct ip_options *opt = NULL;
1112 struct inet_cork *cork;
1113 int hh_len;
1114 int mtu;
1115 int len;
1116 int err;
1117 unsigned int maxfraglen, fragheaderlen, fraggap;
1118
1119 if (inet->hdrincl)
1120 return -EPERM;
1121
1122 if (flags&MSG_PROBE)
1123 return 0;
1124
1125 if (skb_queue_empty(&sk->sk_write_queue))
1126 return -EINVAL;
1127
1128 cork = &inet->cork.base;
1129 rt = (struct rtable *)cork->dst;
1130 if (cork->flags & IPCORK_OPT)
1131 opt = cork->opt;
1132
1133 if (!(rt->dst.dev->features&NETIF_F_SG))
1134 return -EOPNOTSUPP;
1135
1136 hh_len = LL_RESERVED_SPACE(rt->dst.dev);
1137 mtu = cork->fragsize;
1138
1139 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
1140 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
1141
1142 if (cork->length + size > 0xFFFF - fragheaderlen) {
1143 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport, mtu);
1144 return -EMSGSIZE;
1145 }
1146
1147 if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL)
1148 return -EINVAL;
1149
1150 cork->length += size;
1151 if ((size + skb->len > mtu) &&
1152 (sk->sk_protocol == IPPROTO_UDP) &&
1153 (rt->dst.dev->features & NETIF_F_UFO)) {
1154 skb_shinfo(skb)->gso_size = mtu - fragheaderlen;
1155 skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
1156 }
1157
1158
1159 while (size > 0) {
1160 int i;
1161
1162 if (skb_is_gso(skb))
1163 len = size;
1164 else {
1165
1166 /* Check if the remaining data fits into current packet. */
1167 len = mtu - skb->len;
1168 if (len < size)
1169 len = maxfraglen - skb->len;
1170 }
1171 if (len <= 0) {
1172 struct sk_buff *skb_prev;
1173 int alloclen;
1174
1175 skb_prev = skb;
1176 fraggap = skb_prev->len - maxfraglen;
1177
1178 alloclen = fragheaderlen + hh_len + fraggap + 15;
1179 skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation);
1180 if (unlikely(!skb)) {
1181 err = -ENOBUFS;
1182 goto error;
1183 }
1184
1185 /*
1186 * Fill in the control structures
1187 */
1188 skb->ip_summed = CHECKSUM_NONE;
1189 skb->csum = 0;
1190 skb_reserve(skb, hh_len);
1191
1192 /*
1193 * Find where to start putting bytes.
1194 */
1195 skb_put(skb, fragheaderlen + fraggap);
1196 skb_reset_network_header(skb);
1197 skb->transport_header = (skb->network_header +
1198 fragheaderlen);
1199 if (fraggap) {
1200 skb->csum = skb_copy_and_csum_bits(skb_prev,
1201 maxfraglen,
1202 skb_transport_header(skb),
1203 fraggap, 0);
1204 skb_prev->csum = csum_sub(skb_prev->csum,
1205 skb->csum);
1206 pskb_trim_unique(skb_prev, maxfraglen);
1207 }
1208
1209 /*
1210 * Put the packet on the pending queue.
1211 */
1212 __skb_queue_tail(&sk->sk_write_queue, skb);
1213 continue;
1214 }
1215
1216 i = skb_shinfo(skb)->nr_frags;
1217 if (len > size)
1218 len = size;
1219 if (skb_can_coalesce(skb, i, page, offset)) {
1220 skb_frag_size_add(&skb_shinfo(skb)->frags[i-1], len);
1221 } else if (i < MAX_SKB_FRAGS) {
1222 get_page(page);
1223 skb_fill_page_desc(skb, i, page, offset, len);
1224 } else {
1225 err = -EMSGSIZE;
1226 goto error;
1227 }
1228
1229 if (skb->ip_summed == CHECKSUM_NONE) {
1230 __wsum csum;
1231 csum = csum_page(page, offset, len);
1232 skb->csum = csum_block_add(skb->csum, csum, skb->len);
1233 }
1234
1235 skb->len += len;
1236 skb->data_len += len;
1237 skb->truesize += len;
1238 atomic_add(len, &sk->sk_wmem_alloc);
1239 offset += len;
1240 size -= len;
1241 }
1242 return 0;
1243
1244 error:
1245 cork->length -= size;
1246 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1247 return err;
1248 }
1249
1250 static void ip_cork_release(struct inet_cork *cork)
1251 {
1252 cork->flags &= ~IPCORK_OPT;
1253 kfree(cork->opt);
1254 cork->opt = NULL;
1255 dst_release(cork->dst);
1256 cork->dst = NULL;
1257 }
1258
1259 /*
1260 * Combined all pending IP fragments on the socket as one IP datagram
1261 * and push them out.
1262 */
1263 struct sk_buff *__ip_make_skb(struct sock *sk,
1264 struct flowi4 *fl4,
1265 struct sk_buff_head *queue,
1266 struct inet_cork *cork)
1267 {
1268 struct sk_buff *skb, *tmp_skb;
1269 struct sk_buff **tail_skb;
1270 struct inet_sock *inet = inet_sk(sk);
1271 struct net *net = sock_net(sk);
1272 struct ip_options *opt = NULL;
1273 struct rtable *rt = (struct rtable *)cork->dst;
1274 struct iphdr *iph;
1275 __be16 df = 0;
1276 __u8 ttl;
1277
1278 if ((skb = __skb_dequeue(queue)) == NULL)
1279 goto out;
1280 tail_skb = &(skb_shinfo(skb)->frag_list);
1281
1282 /* move skb->data to ip header from ext header */
1283 if (skb->data < skb_network_header(skb))
1284 __skb_pull(skb, skb_network_offset(skb));
1285 while ((tmp_skb = __skb_dequeue(queue)) != NULL) {
1286 __skb_pull(tmp_skb, skb_network_header_len(skb));
1287 *tail_skb = tmp_skb;
1288 tail_skb = &(tmp_skb->next);
1289 skb->len += tmp_skb->len;
1290 skb->data_len += tmp_skb->len;
1291 skb->truesize += tmp_skb->truesize;
1292 tmp_skb->destructor = NULL;
1293 tmp_skb->sk = NULL;
1294 }
1295
1296 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow
1297 * to fragment the frame generated here. No matter, what transforms
1298 * how transforms change size of the packet, it will come out.
1299 */
1300 if (inet->pmtudisc < IP_PMTUDISC_DO)
1301 skb->local_df = 1;
1302
1303 /* DF bit is set when we want to see DF on outgoing frames.
1304 * If local_df is set too, we still allow to fragment this frame
1305 * locally. */
1306 if (inet->pmtudisc >= IP_PMTUDISC_DO ||
1307 (skb->len <= dst_mtu(&rt->dst) &&
1308 ip_dont_fragment(sk, &rt->dst)))
1309 df = htons(IP_DF);
1310
1311 if (cork->flags & IPCORK_OPT)
1312 opt = cork->opt;
1313
1314 if (rt->rt_type == RTN_MULTICAST)
1315 ttl = inet->mc_ttl;
1316 else
1317 ttl = ip_select_ttl(inet, &rt->dst);
1318
1319 iph = ip_hdr(skb);
1320 iph->version = 4;
1321 iph->ihl = 5;
1322 iph->tos = inet->tos;
1323 iph->frag_off = df;
1324 iph->ttl = ttl;
1325 iph->protocol = sk->sk_protocol;
1326 ip_copy_addrs(iph, fl4);
1327 ip_select_ident(skb, &rt->dst, sk);
1328
1329 if (opt) {
1330 iph->ihl += opt->optlen>>2;
1331 ip_options_build(skb, opt, cork->addr, rt, 0);
1332 }
1333
1334 skb->priority = sk->sk_priority;
1335 skb->mark = sk->sk_mark;
1336 /*
1337 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec
1338 * on dst refcount
1339 */
1340 cork->dst = NULL;
1341 skb_dst_set(skb, &rt->dst);
1342
1343 if (iph->protocol == IPPROTO_ICMP)
1344 icmp_out_count(net, ((struct icmphdr *)
1345 skb_transport_header(skb))->type);
1346
1347 ip_cork_release(cork);
1348 out:
1349 return skb;
1350 }
1351
1352 int ip_send_skb(struct net *net, struct sk_buff *skb)
1353 {
1354 int err;
1355
1356 err = ip_local_out(skb);
1357 if (err) {
1358 if (err > 0)
1359 err = net_xmit_errno(err);
1360 if (err)
1361 IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS);
1362 }
1363
1364 return err;
1365 }
1366
1367 int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4)
1368 {
1369 struct sk_buff *skb;
1370
1371 skb = ip_finish_skb(sk, fl4);
1372 if (!skb)
1373 return 0;
1374
1375 /* Netfilter gets whole the not fragmented skb. */
1376 return ip_send_skb(sock_net(sk), skb);
1377 }
1378
1379 /*
1380 * Throw away all pending data on the socket.
1381 */
1382 static void __ip_flush_pending_frames(struct sock *sk,
1383 struct sk_buff_head *queue,
1384 struct inet_cork *cork)
1385 {
1386 struct sk_buff *skb;
1387
1388 while ((skb = __skb_dequeue_tail(queue)) != NULL)
1389 kfree_skb(skb);
1390
1391 ip_cork_release(cork);
1392 }
1393
1394 void ip_flush_pending_frames(struct sock *sk)
1395 {
1396 __ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork.base);
1397 }
1398
1399 struct sk_buff *ip_make_skb(struct sock *sk,
1400 struct flowi4 *fl4,
1401 int getfrag(void *from, char *to, int offset,
1402 int len, int odd, struct sk_buff *skb),
1403 void *from, int length, int transhdrlen,
1404 struct ipcm_cookie *ipc, struct rtable **rtp,
1405 unsigned int flags)
1406 {
1407 struct inet_cork cork;
1408 struct sk_buff_head queue;
1409 int err;
1410
1411 if (flags & MSG_PROBE)
1412 return NULL;
1413
1414 __skb_queue_head_init(&queue);
1415
1416 cork.flags = 0;
1417 cork.addr = 0;
1418 cork.opt = NULL;
1419 err = ip_setup_cork(sk, &cork, ipc, rtp);
1420 if (err)
1421 return ERR_PTR(err);
1422
1423 err = __ip_append_data(sk, fl4, &queue, &cork,
1424 &current->task_frag, getfrag,
1425 from, length, transhdrlen, flags);
1426 if (err) {
1427 __ip_flush_pending_frames(sk, &queue, &cork);
1428 return ERR_PTR(err);
1429 }
1430
1431 return __ip_make_skb(sk, fl4, &queue, &cork);
1432 }
1433
1434 /*
1435 * Fetch data from kernel space and fill in checksum if needed.
1436 */
1437 static int ip_reply_glue_bits(void *dptr, char *to, int offset,
1438 int len, int odd, struct sk_buff *skb)
1439 {
1440 __wsum csum;
1441
1442 csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0);
1443 skb->csum = csum_block_add(skb->csum, csum, odd);
1444 return 0;
1445 }
1446
1447 /*
1448 * Generic function to send a packet as reply to another packet.
1449 * Used to send some TCP resets/acks so far.
1450 *
1451 * Use a fake percpu inet socket to avoid false sharing and contention.
1452 */
1453 static DEFINE_PER_CPU(struct inet_sock, unicast_sock) = {
1454 .sk = {
1455 .__sk_common = {
1456 .skc_refcnt = ATOMIC_INIT(1),
1457 },
1458 .sk_wmem_alloc = ATOMIC_INIT(1),
1459 .sk_allocation = GFP_ATOMIC,
1460 .sk_flags = (1UL << SOCK_USE_WRITE_QUEUE),
1461 },
1462 .pmtudisc = IP_PMTUDISC_WANT,
1463 .uc_ttl = -1,
1464 };
1465
1466 void ip_send_unicast_reply(struct net *net, struct sk_buff *skb, __be32 daddr,
1467 __be32 saddr, const struct ip_reply_arg *arg,
1468 unsigned int len)
1469 {
1470 struct ip_options_data replyopts;
1471 struct ipcm_cookie ipc;
1472 struct flowi4 fl4;
1473 struct rtable *rt = skb_rtable(skb);
1474 struct sk_buff *nskb;
1475 struct sock *sk;
1476 struct inet_sock *inet;
1477
1478 if (ip_options_echo(&replyopts.opt.opt, skb))
1479 return;
1480
1481 ipc.addr = daddr;
1482 ipc.opt = NULL;
1483 ipc.tx_flags = 0;
1484
1485 if (replyopts.opt.opt.optlen) {
1486 ipc.opt = &replyopts.opt;
1487
1488 if (replyopts.opt.opt.srr)
1489 daddr = replyopts.opt.opt.faddr;
1490 }
1491
1492 flowi4_init_output(&fl4, arg->bound_dev_if, 0,
1493 RT_TOS(arg->tos),
1494 RT_SCOPE_UNIVERSE, ip_hdr(skb)->protocol,
1495 ip_reply_arg_flowi_flags(arg),
1496 daddr, saddr,
1497 tcp_hdr(skb)->source, tcp_hdr(skb)->dest);
1498 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
1499 rt = ip_route_output_key(net, &fl4);
1500 if (IS_ERR(rt))
1501 return;
1502
1503 inet = &get_cpu_var(unicast_sock);
1504
1505 inet->tos = arg->tos;
1506 sk = &inet->sk;
1507 sk->sk_priority = skb->priority;
1508 sk->sk_protocol = ip_hdr(skb)->protocol;
1509 sk->sk_bound_dev_if = arg->bound_dev_if;
1510 sock_net_set(sk, net);
1511 __skb_queue_head_init(&sk->sk_write_queue);
1512 sk->sk_sndbuf = sysctl_wmem_default;
1513 ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base, len, 0,
1514 &ipc, &rt, MSG_DONTWAIT);
1515 nskb = skb_peek(&sk->sk_write_queue);
1516 if (nskb) {
1517 if (arg->csumoffset >= 0)
1518 *((__sum16 *)skb_transport_header(nskb) +
1519 arg->csumoffset) = csum_fold(csum_add(nskb->csum,
1520 arg->csum));
1521 nskb->ip_summed = CHECKSUM_NONE;
1522 skb_orphan(nskb);
1523 skb_set_queue_mapping(nskb, skb_get_queue_mapping(skb));
1524 ip_push_pending_frames(sk, &fl4);
1525 }
1526
1527 put_cpu_var(unicast_sock);
1528
1529 ip_rt_put(rt);
1530 }
1531
1532 void __init ip_init(void)
1533 {
1534 ip_rt_init();
1535 inet_initpeers();
1536
1537 #if defined(CONFIG_IP_MULTICAST) && defined(CONFIG_PROC_FS)
1538 igmp_mc_proc_init();
1539 #endif
1540 }
Linux kernel - Deliverables
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