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. */
ip_send_check(struct iphdr * iph)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
__ip_local_out(struct sk_buff * skb)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
ip_local_out(struct sk_buff * skb)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
ip_select_ttl(struct inet_sock * inet,struct dst_entry * dst)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 */
ip_build_and_send_pkt(struct sk_buff * skb,struct sock * sk,__be32 saddr,__be32 daddr,struct ip_options_rcu * opt)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
ip_finish_output2(struct sk_buff * skb)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
ip_skb_dst_mtu(struct sk_buff * skb)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
ip_finish_output(struct sk_buff * skb)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
ip_mc_output(struct sk_buff * skb)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
ip_output(struct sk_buff * skb)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 */
ip_copy_addrs(struct iphdr * iph,const struct flowi4 * fl4)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
ip_queue_xmit(struct sk_buff * skb,struct flowi * fl)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_uses_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
ip_copy_metadata(struct sk_buff * to,struct sk_buff * from)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 IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TRACE)
434 to->nf_trace = from->nf_trace;
435 #endif
436 #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
437 to->ipvs_property = from->ipvs_property;
438 #endif
439 skb_copy_secmark(to, from);
440 }
441
442 /*
443 * This IP datagram is too large to be sent in one piece. Break it up into
444 * smaller pieces (each of size equal to IP header plus
445 * a block of the data of the original IP data part) that will yet fit in a
446 * single device frame, and queue such a frame for sending.
447 */
448
ip_fragment(struct sk_buff * skb,int (* output)(struct sk_buff *))449 int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *))
450 {
451 struct iphdr *iph;
452 int ptr;
453 struct net_device *dev;
454 struct sk_buff *skb2;
455 unsigned int mtu, hlen, left, len, ll_rs;
456 int offset;
457 __be16 not_last_frag;
458 struct rtable *rt = skb_rtable(skb);
459 int err = 0;
460
461 dev = rt->dst.dev;
462
463 /*
464 * Point into the IP datagram header.
465 */
466
467 iph = ip_hdr(skb);
468
469 if (unlikely(((iph->frag_off & htons(IP_DF)) && !skb->local_df) ||
470 (IPCB(skb)->frag_max_size &&
471 IPCB(skb)->frag_max_size > dst_mtu(&rt->dst)))) {
472 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
473 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
474 htonl(ip_skb_dst_mtu(skb)));
475 kfree_skb(skb);
476 return -EMSGSIZE;
477 }
478
479 /*
480 * Setup starting values.
481 */
482
483 hlen = iph->ihl * 4;
484 mtu = dst_mtu(&rt->dst) - hlen; /* Size of data space */
485 #ifdef CONFIG_BRIDGE_NETFILTER
486 if (skb->nf_bridge)
487 mtu -= nf_bridge_mtu_reduction(skb);
488 #endif
489 IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE;
490
491 /* When frag_list is given, use it. First, check its validity:
492 * some transformers could create wrong frag_list or break existing
493 * one, it is not prohibited. In this case fall back to copying.
494 *
495 * LATER: this step can be merged to real generation of fragments,
496 * we can switch to copy when see the first bad fragment.
497 */
498 if (skb_has_frag_list(skb)) {
499 struct sk_buff *frag, *frag2;
500 int first_len = skb_pagelen(skb);
501
502 if (first_len - hlen > mtu ||
503 ((first_len - hlen) & 7) ||
504 ip_is_fragment(iph) ||
505 skb_cloned(skb))
506 goto slow_path;
507
508 skb_walk_frags(skb, frag) {
509 /* Correct geometry. */
510 if (frag->len > mtu ||
511 ((frag->len & 7) && frag->next) ||
512 skb_headroom(frag) < hlen)
513 goto slow_path_clean;
514
515 /* Partially cloned skb? */
516 if (skb_shared(frag))
517 goto slow_path_clean;
518
519 BUG_ON(frag->sk);
520 if (skb->sk) {
521 frag->sk = skb->sk;
522 frag->destructor = sock_wfree;
523 }
524 skb->truesize -= frag->truesize;
525 }
526
527 /* Everything is OK. Generate! */
528
529 err = 0;
530 offset = 0;
531 frag = skb_shinfo(skb)->frag_list;
532 skb_frag_list_init(skb);
533 skb->data_len = first_len - skb_headlen(skb);
534 skb->len = first_len;
535 iph->tot_len = htons(first_len);
536 iph->frag_off = htons(IP_MF);
537 ip_send_check(iph);
538
539 for (;;) {
540 /* Prepare header of the next frame,
541 * before previous one went down. */
542 if (frag) {
543 frag->ip_summed = CHECKSUM_NONE;
544 skb_reset_transport_header(frag);
545 __skb_push(frag, hlen);
546 skb_reset_network_header(frag);
547 memcpy(skb_network_header(frag), iph, hlen);
548 iph = ip_hdr(frag);
549 iph->tot_len = htons(frag->len);
550 ip_copy_metadata(frag, skb);
551 if (offset == 0)
552 ip_options_fragment(frag);
553 offset += skb->len - hlen;
554 iph->frag_off = htons(offset>>3);
555 if (frag->next != NULL)
556 iph->frag_off |= htons(IP_MF);
557 /* Ready, complete checksum */
558 ip_send_check(iph);
559 }
560
561 err = output(skb);
562
563 if (!err)
564 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES);
565 if (err || !frag)
566 break;
567
568 skb = frag;
569 frag = skb->next;
570 skb->next = NULL;
571 }
572
573 if (err == 0) {
574 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS);
575 return 0;
576 }
577
578 while (frag) {
579 skb = frag->next;
580 kfree_skb(frag);
581 frag = skb;
582 }
583 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
584 return err;
585
586 slow_path_clean:
587 skb_walk_frags(skb, frag2) {
588 if (frag2 == frag)
589 break;
590 frag2->sk = NULL;
591 frag2->destructor = NULL;
592 skb->truesize += frag2->truesize;
593 }
594 }
595
596 slow_path:
597 /* for offloaded checksums cleanup checksum before fragmentation */
598 if ((skb->ip_summed == CHECKSUM_PARTIAL) && skb_checksum_help(skb))
599 goto fail;
600 iph = ip_hdr(skb);
601
602 left = skb->len - hlen; /* Space per frame */
603 ptr = hlen; /* Where to start from */
604
605 /* for bridged IP traffic encapsulated inside f.e. a vlan header,
606 * we need to make room for the encapsulating header
607 */
608 ll_rs = LL_RESERVED_SPACE_EXTRA(rt->dst.dev, nf_bridge_pad(skb));
609
610 /*
611 * Fragment the datagram.
612 */
613
614 offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3;
615 not_last_frag = iph->frag_off & htons(IP_MF);
616
617 /*
618 * Keep copying data until we run out.
619 */
620
621 while (left > 0) {
622 len = left;
623 /* IF: it doesn't fit, use 'mtu' - the data space left */
624 if (len > mtu)
625 len = mtu;
626 /* IF: we are not sending up to and including the packet end
627 then align the next start on an eight byte boundary */
628 if (len < left) {
629 len &= ~7;
630 }
631 /*
632 * Allocate buffer.
633 */
634
635 if ((skb2 = alloc_skb(len+hlen+ll_rs, GFP_ATOMIC)) == NULL) {
636 NETDEBUG(KERN_INFO "IP: frag: no memory for new fragment!\n");
637 err = -ENOMEM;
638 goto fail;
639 }
640
641 /*
642 * Set up data on packet
643 */
644
645 ip_copy_metadata(skb2, skb);
646 skb_reserve(skb2, ll_rs);
647 skb_put(skb2, len + hlen);
648 skb_reset_network_header(skb2);
649 skb2->transport_header = skb2->network_header + hlen;
650
651 /*
652 * Charge the memory for the fragment to any owner
653 * it might possess
654 */
655
656 if (skb->sk)
657 skb_set_owner_w(skb2, skb->sk);
658
659 /*
660 * Copy the packet header into the new buffer.
661 */
662
663 skb_copy_from_linear_data(skb, skb_network_header(skb2), hlen);
664
665 /*
666 * Copy a block of the IP datagram.
667 */
668 if (skb_copy_bits(skb, ptr, skb_transport_header(skb2), len))
669 BUG();
670 left -= len;
671
672 /*
673 * Fill in the new header fields.
674 */
675 iph = ip_hdr(skb2);
676 iph->frag_off = htons((offset >> 3));
677
678 /* ANK: dirty, but effective trick. Upgrade options only if
679 * the segment to be fragmented was THE FIRST (otherwise,
680 * options are already fixed) and make it ONCE
681 * on the initial skb, so that all the following fragments
682 * will inherit fixed options.
683 */
684 if (offset == 0)
685 ip_options_fragment(skb);
686
687 /*
688 * Added AC : If we are fragmenting a fragment that's not the
689 * last fragment then keep MF on each bit
690 */
691 if (left > 0 || not_last_frag)
692 iph->frag_off |= htons(IP_MF);
693 ptr += len;
694 offset += len;
695
696 /*
697 * Put this fragment into the sending queue.
698 */
699 iph->tot_len = htons(len + hlen);
700
701 ip_send_check(iph);
702
703 err = output(skb2);
704 if (err)
705 goto fail;
706
707 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES);
708 }
709 consume_skb(skb);
710 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS);
711 return err;
712
713 fail:
714 kfree_skb(skb);
715 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
716 return err;
717 }
718 EXPORT_SYMBOL(ip_fragment);
719
720 int
ip_generic_getfrag(void * from,char * to,int offset,int len,int odd,struct sk_buff * skb)721 ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
722 {
723 struct iovec *iov = from;
724
725 if (skb->ip_summed == CHECKSUM_PARTIAL) {
726 if (memcpy_fromiovecend(to, iov, offset, len) < 0)
727 return -EFAULT;
728 } else {
729 __wsum csum = 0;
730 if (csum_partial_copy_fromiovecend(to, iov, offset, len, &csum) < 0)
731 return -EFAULT;
732 skb->csum = csum_block_add(skb->csum, csum, odd);
733 }
734 return 0;
735 }
736 EXPORT_SYMBOL(ip_generic_getfrag);
737
738 static inline __wsum
csum_page(struct page * page,int offset,int copy)739 csum_page(struct page *page, int offset, int copy)
740 {
741 char *kaddr;
742 __wsum csum;
743 kaddr = kmap(page);
744 csum = csum_partial(kaddr + offset, copy, 0);
745 kunmap(page);
746 return csum;
747 }
748
ip_ufo_append_data(struct sock * sk,struct sk_buff_head * queue,int getfrag (void * from,char * to,int offset,int len,int odd,struct sk_buff * skb),void * from,int length,int hh_len,int fragheaderlen,int transhdrlen,int maxfraglen,unsigned int flags)749 static inline int ip_ufo_append_data(struct sock *sk,
750 struct sk_buff_head *queue,
751 int getfrag(void *from, char *to, int offset, int len,
752 int odd, struct sk_buff *skb),
753 void *from, int length, int hh_len, int fragheaderlen,
754 int transhdrlen, int maxfraglen, unsigned int flags)
755 {
756 struct sk_buff *skb;
757 int err;
758
759 /* There is support for UDP fragmentation offload by network
760 * device, so create one single skb packet containing complete
761 * udp datagram
762 */
763 if ((skb = skb_peek_tail(queue)) == NULL) {
764 skb = sock_alloc_send_skb(sk,
765 hh_len + fragheaderlen + transhdrlen + 20,
766 (flags & MSG_DONTWAIT), &err);
767
768 if (skb == NULL)
769 return err;
770
771 /* reserve space for Hardware header */
772 skb_reserve(skb, hh_len);
773
774 /* create space for UDP/IP header */
775 skb_put(skb, fragheaderlen + transhdrlen);
776
777 /* initialize network header pointer */
778 skb_reset_network_header(skb);
779
780 /* initialize protocol header pointer */
781 skb->transport_header = skb->network_header + fragheaderlen;
782
783 skb->ip_summed = CHECKSUM_PARTIAL;
784 skb->csum = 0;
785
786 /* specify the length of each IP datagram fragment */
787 skb_shinfo(skb)->gso_size = maxfraglen - fragheaderlen;
788 skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
789 __skb_queue_tail(queue, skb);
790 }
791
792 return skb_append_datato_frags(sk, skb, getfrag, from,
793 (length - transhdrlen));
794 }
795
__ip_append_data(struct sock * sk,struct flowi4 * fl4,struct sk_buff_head * queue,struct inet_cork * cork,struct page_frag * pfrag,int getfrag (void * from,char * to,int offset,int len,int odd,struct sk_buff * skb),void * from,int length,int transhdrlen,unsigned int flags)796 static int __ip_append_data(struct sock *sk,
797 struct flowi4 *fl4,
798 struct sk_buff_head *queue,
799 struct inet_cork *cork,
800 struct page_frag *pfrag,
801 int getfrag(void *from, char *to, int offset,
802 int len, int odd, struct sk_buff *skb),
803 void *from, int length, int transhdrlen,
804 unsigned int flags)
805 {
806 struct inet_sock *inet = inet_sk(sk);
807 struct sk_buff *skb;
808
809 struct ip_options *opt = cork->opt;
810 int hh_len;
811 int exthdrlen;
812 int mtu;
813 int copy;
814 int err;
815 int offset = 0;
816 unsigned int maxfraglen, fragheaderlen;
817 int csummode = CHECKSUM_NONE;
818 struct rtable *rt = (struct rtable *)cork->dst;
819
820 skb = skb_peek_tail(queue);
821
822 exthdrlen = !skb ? rt->dst.header_len : 0;
823 mtu = cork->fragsize;
824
825 hh_len = LL_RESERVED_SPACE(rt->dst.dev);
826
827 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
828 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
829
830 if (cork->length + length > 0xFFFF - fragheaderlen) {
831 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
832 mtu-exthdrlen);
833 return -EMSGSIZE;
834 }
835
836 /*
837 * transhdrlen > 0 means that this is the first fragment and we wish
838 * it won't be fragmented in the future.
839 */
840 if (transhdrlen &&
841 length + fragheaderlen <= mtu &&
842 rt->dst.dev->features & NETIF_F_V4_CSUM &&
843 !exthdrlen)
844 csummode = CHECKSUM_PARTIAL;
845
846 cork->length += length;
847 if (((length > mtu) || (skb && skb_is_gso(skb))) &&
848 (sk->sk_protocol == IPPROTO_UDP) &&
849 (rt->dst.dev->features & NETIF_F_UFO) && !rt->dst.header_len) {
850 err = ip_ufo_append_data(sk, queue, getfrag, from, length,
851 hh_len, fragheaderlen, transhdrlen,
852 maxfraglen, flags);
853 if (err)
854 goto error;
855 return 0;
856 }
857
858 /* So, what's going on in the loop below?
859 *
860 * We use calculated fragment length to generate chained skb,
861 * each of segments is IP fragment ready for sending to network after
862 * adding appropriate IP header.
863 */
864
865 if (!skb)
866 goto alloc_new_skb;
867
868 while (length > 0) {
869 /* Check if the remaining data fits into current packet. */
870 copy = mtu - skb->len;
871 if (copy < length)
872 copy = maxfraglen - skb->len;
873 if (copy <= 0) {
874 char *data;
875 unsigned int datalen;
876 unsigned int fraglen;
877 unsigned int fraggap;
878 unsigned int alloclen;
879 struct sk_buff *skb_prev;
880 alloc_new_skb:
881 skb_prev = skb;
882 if (skb_prev)
883 fraggap = skb_prev->len - maxfraglen;
884 else
885 fraggap = 0;
886
887 /*
888 * If remaining data exceeds the mtu,
889 * we know we need more fragment(s).
890 */
891 datalen = length + fraggap;
892 if (datalen > mtu - fragheaderlen)
893 datalen = maxfraglen - fragheaderlen;
894 fraglen = datalen + fragheaderlen;
895
896 if ((flags & MSG_MORE) &&
897 !(rt->dst.dev->features&NETIF_F_SG))
898 alloclen = mtu;
899 else
900 alloclen = fraglen;
901
902 alloclen += exthdrlen;
903
904 /* The last fragment gets additional space at tail.
905 * Note, with MSG_MORE we overallocate on fragments,
906 * because we have no idea what fragment will be
907 * the last.
908 */
909 if (datalen == length + fraggap)
910 alloclen += rt->dst.trailer_len;
911
912 if (transhdrlen) {
913 skb = sock_alloc_send_skb(sk,
914 alloclen + hh_len + 15,
915 (flags & MSG_DONTWAIT), &err);
916 } else {
917 skb = NULL;
918 if (atomic_read(&sk->sk_wmem_alloc) <=
919 2 * sk->sk_sndbuf)
920 skb = sock_wmalloc(sk,
921 alloclen + hh_len + 15, 1,
922 sk->sk_allocation);
923 if (unlikely(skb == NULL))
924 err = -ENOBUFS;
925 else
926 /* only the initial fragment is
927 time stamped */
928 cork->tx_flags = 0;
929 }
930 if (skb == NULL)
931 goto error;
932
933 /*
934 * Fill in the control structures
935 */
936 skb->ip_summed = csummode;
937 skb->csum = 0;
938 skb_reserve(skb, hh_len);
939 skb_shinfo(skb)->tx_flags = cork->tx_flags;
940
941 /*
942 * Find where to start putting bytes.
943 */
944 data = skb_put(skb, fraglen + exthdrlen);
945 skb_set_network_header(skb, exthdrlen);
946 skb->transport_header = (skb->network_header +
947 fragheaderlen);
948 data += fragheaderlen + exthdrlen;
949
950 if (fraggap) {
951 skb->csum = skb_copy_and_csum_bits(
952 skb_prev, maxfraglen,
953 data + transhdrlen, fraggap, 0);
954 skb_prev->csum = csum_sub(skb_prev->csum,
955 skb->csum);
956 data += fraggap;
957 pskb_trim_unique(skb_prev, maxfraglen);
958 }
959
960 copy = datalen - transhdrlen - fraggap;
961 if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) {
962 err = -EFAULT;
963 kfree_skb(skb);
964 goto error;
965 }
966
967 offset += copy;
968 length -= datalen - fraggap;
969 transhdrlen = 0;
970 exthdrlen = 0;
971 csummode = CHECKSUM_NONE;
972
973 /*
974 * Put the packet on the pending queue.
975 */
976 __skb_queue_tail(queue, skb);
977 continue;
978 }
979
980 if (copy > length)
981 copy = length;
982
983 if (!(rt->dst.dev->features&NETIF_F_SG)) {
984 unsigned int off;
985
986 off = skb->len;
987 if (getfrag(from, skb_put(skb, copy),
988 offset, copy, off, skb) < 0) {
989 __skb_trim(skb, off);
990 err = -EFAULT;
991 goto error;
992 }
993 } else {
994 int i = skb_shinfo(skb)->nr_frags;
995
996 err = -ENOMEM;
997 if (!sk_page_frag_refill(sk, pfrag))
998 goto error;
999
1000 if (!skb_can_coalesce(skb, i, pfrag->page,
1001 pfrag->offset)) {
1002 err = -EMSGSIZE;
1003 if (i == MAX_SKB_FRAGS)
1004 goto error;
1005
1006 __skb_fill_page_desc(skb, i, pfrag->page,
1007 pfrag->offset, 0);
1008 skb_shinfo(skb)->nr_frags = ++i;
1009 get_page(pfrag->page);
1010 }
1011 copy = min_t(int, copy, pfrag->size - pfrag->offset);
1012 if (getfrag(from,
1013 page_address(pfrag->page) + pfrag->offset,
1014 offset, copy, skb->len, skb) < 0)
1015 goto error_efault;
1016
1017 pfrag->offset += copy;
1018 skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
1019 skb->len += copy;
1020 skb->data_len += copy;
1021 skb->truesize += copy;
1022 atomic_add(copy, &sk->sk_wmem_alloc);
1023 }
1024 offset += copy;
1025 length -= copy;
1026 }
1027
1028 return 0;
1029
1030 error_efault:
1031 err = -EFAULT;
1032 error:
1033 cork->length -= length;
1034 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1035 return err;
1036 }
1037
ip_setup_cork(struct sock * sk,struct inet_cork * cork,struct ipcm_cookie * ipc,struct rtable ** rtp)1038 static int ip_setup_cork(struct sock *sk, struct inet_cork *cork,
1039 struct ipcm_cookie *ipc, struct rtable **rtp)
1040 {
1041 struct inet_sock *inet = inet_sk(sk);
1042 struct ip_options_rcu *opt;
1043 struct rtable *rt;
1044
1045 /*
1046 * setup for corking.
1047 */
1048 opt = ipc->opt;
1049 if (opt) {
1050 if (cork->opt == NULL) {
1051 cork->opt = kmalloc(sizeof(struct ip_options) + 40,
1052 sk->sk_allocation);
1053 if (unlikely(cork->opt == NULL))
1054 return -ENOBUFS;
1055 }
1056 memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen);
1057 cork->flags |= IPCORK_OPT;
1058 cork->addr = ipc->addr;
1059 }
1060 rt = *rtp;
1061 if (unlikely(!rt))
1062 return -EFAULT;
1063 /*
1064 * We steal reference to this route, caller should not release it
1065 */
1066 *rtp = NULL;
1067 cork->fragsize = inet->pmtudisc == IP_PMTUDISC_PROBE ?
1068 rt->dst.dev->mtu : dst_mtu(&rt->dst);
1069 cork->dst = &rt->dst;
1070 cork->length = 0;
1071 cork->tx_flags = ipc->tx_flags;
1072
1073 return 0;
1074 }
1075
1076 /*
1077 * ip_append_data() and ip_append_page() can make one large IP datagram
1078 * from many pieces of data. Each pieces will be holded on the socket
1079 * until ip_push_pending_frames() is called. Each piece can be a page
1080 * or non-page data.
1081 *
1082 * Not only UDP, other transport protocols - e.g. raw sockets - can use
1083 * this interface potentially.
1084 *
1085 * LATER: length must be adjusted by pad at tail, when it is required.
1086 */
ip_append_data(struct sock * sk,struct flowi4 * fl4,int getfrag (void * from,char * to,int offset,int len,int odd,struct sk_buff * skb),void * from,int length,int transhdrlen,struct ipcm_cookie * ipc,struct rtable ** rtp,unsigned int flags)1087 int ip_append_data(struct sock *sk, struct flowi4 *fl4,
1088 int getfrag(void *from, char *to, int offset, int len,
1089 int odd, struct sk_buff *skb),
1090 void *from, int length, int transhdrlen,
1091 struct ipcm_cookie *ipc, struct rtable **rtp,
1092 unsigned int flags)
1093 {
1094 struct inet_sock *inet = inet_sk(sk);
1095 int err;
1096
1097 if (flags&MSG_PROBE)
1098 return 0;
1099
1100 if (skb_queue_empty(&sk->sk_write_queue)) {
1101 err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp);
1102 if (err)
1103 return err;
1104 } else {
1105 transhdrlen = 0;
1106 }
1107
1108 return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base,
1109 sk_page_frag(sk), getfrag,
1110 from, length, transhdrlen, flags);
1111 }
1112
ip_append_page(struct sock * sk,struct flowi4 * fl4,struct page * page,int offset,size_t size,int flags)1113 ssize_t ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page,
1114 int offset, size_t size, int flags)
1115 {
1116 struct inet_sock *inet = inet_sk(sk);
1117 struct sk_buff *skb;
1118 struct rtable *rt;
1119 struct ip_options *opt = NULL;
1120 struct inet_cork *cork;
1121 int hh_len;
1122 int mtu;
1123 int len;
1124 int err;
1125 unsigned int maxfraglen, fragheaderlen, fraggap;
1126
1127 if (inet->hdrincl)
1128 return -EPERM;
1129
1130 if (flags&MSG_PROBE)
1131 return 0;
1132
1133 if (skb_queue_empty(&sk->sk_write_queue))
1134 return -EINVAL;
1135
1136 cork = &inet->cork.base;
1137 rt = (struct rtable *)cork->dst;
1138 if (cork->flags & IPCORK_OPT)
1139 opt = cork->opt;
1140
1141 if (!(rt->dst.dev->features&NETIF_F_SG))
1142 return -EOPNOTSUPP;
1143
1144 hh_len = LL_RESERVED_SPACE(rt->dst.dev);
1145 mtu = cork->fragsize;
1146
1147 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
1148 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
1149
1150 if (cork->length + size > 0xFFFF - fragheaderlen) {
1151 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport, mtu);
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
ip_cork_release(struct inet_cork * cork)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 */
__ip_make_skb(struct sock * sk,struct flowi4 * fl4,struct sk_buff_head * queue,struct inet_cork * cork)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 if (inet->pmtudisc < IP_PMTUDISC_DO)
1309 skb->local_df = 1;
1310
1311 /* DF bit is set when we want to see DF on outgoing frames.
1312 * If local_df is set too, we still allow to fragment this frame
1313 * locally. */
1314 if (inet->pmtudisc >= IP_PMTUDISC_DO ||
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 (rt->rt_type == RTN_MULTICAST)
1323 ttl = inet->mc_ttl;
1324 else
1325 ttl = ip_select_ttl(inet, &rt->dst);
1326
1327 iph = (struct iphdr *)skb->data;
1328 iph->version = 4;
1329 iph->ihl = 5;
1330 iph->tos = inet->tos;
1331 iph->frag_off = df;
1332 iph->ttl = ttl;
1333 iph->protocol = sk->sk_protocol;
1334 ip_copy_addrs(iph, fl4);
1335 ip_select_ident(iph, &rt->dst, sk);
1336
1337 if (opt) {
1338 iph->ihl += opt->optlen>>2;
1339 ip_options_build(skb, opt, cork->addr, rt, 0);
1340 }
1341
1342 skb->priority = sk->sk_priority;
1343 skb->mark = sk->sk_mark;
1344 /*
1345 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec
1346 * on dst refcount
1347 */
1348 cork->dst = NULL;
1349 skb_dst_set(skb, &rt->dst);
1350
1351 if (iph->protocol == IPPROTO_ICMP)
1352 icmp_out_count(net, ((struct icmphdr *)
1353 skb_transport_header(skb))->type);
1354
1355 ip_cork_release(cork);
1356 out:
1357 return skb;
1358 }
1359
ip_send_skb(struct net * net,struct sk_buff * skb)1360 int ip_send_skb(struct net *net, struct sk_buff *skb)
1361 {
1362 int err;
1363
1364 err = ip_local_out(skb);
1365 if (err) {
1366 if (err > 0)
1367 err = net_xmit_errno(err);
1368 if (err)
1369 IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS);
1370 }
1371
1372 return err;
1373 }
1374
ip_push_pending_frames(struct sock * sk,struct flowi4 * fl4)1375 int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4)
1376 {
1377 struct sk_buff *skb;
1378
1379 skb = ip_finish_skb(sk, fl4);
1380 if (!skb)
1381 return 0;
1382
1383 /* Netfilter gets whole the not fragmented skb. */
1384 return ip_send_skb(sock_net(sk), skb);
1385 }
1386
1387 /*
1388 * Throw away all pending data on the socket.
1389 */
__ip_flush_pending_frames(struct sock * sk,struct sk_buff_head * queue,struct inet_cork * cork)1390 static void __ip_flush_pending_frames(struct sock *sk,
1391 struct sk_buff_head *queue,
1392 struct inet_cork *cork)
1393 {
1394 struct sk_buff *skb;
1395
1396 while ((skb = __skb_dequeue_tail(queue)) != NULL)
1397 kfree_skb(skb);
1398
1399 ip_cork_release(cork);
1400 }
1401
ip_flush_pending_frames(struct sock * sk)1402 void ip_flush_pending_frames(struct sock *sk)
1403 {
1404 __ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork.base);
1405 }
1406
ip_make_skb(struct sock * sk,struct flowi4 * fl4,int getfrag (void * from,char * to,int offset,int len,int odd,struct sk_buff * skb),void * from,int length,int transhdrlen,struct ipcm_cookie * ipc,struct rtable ** rtp,unsigned int flags)1407 struct sk_buff *ip_make_skb(struct sock *sk,
1408 struct flowi4 *fl4,
1409 int getfrag(void *from, char *to, int offset,
1410 int len, int odd, struct sk_buff *skb),
1411 void *from, int length, int transhdrlen,
1412 struct ipcm_cookie *ipc, struct rtable **rtp,
1413 unsigned int flags)
1414 {
1415 struct inet_cork cork;
1416 struct sk_buff_head queue;
1417 int err;
1418
1419 if (flags & MSG_PROBE)
1420 return NULL;
1421
1422 __skb_queue_head_init(&queue);
1423
1424 cork.flags = 0;
1425 cork.addr = 0;
1426 cork.opt = NULL;
1427 err = ip_setup_cork(sk, &cork, ipc, rtp);
1428 if (err)
1429 return ERR_PTR(err);
1430
1431 err = __ip_append_data(sk, fl4, &queue, &cork,
1432 ¤t->task_frag, getfrag,
1433 from, length, transhdrlen, flags);
1434 if (err) {
1435 __ip_flush_pending_frames(sk, &queue, &cork);
1436 return ERR_PTR(err);
1437 }
1438
1439 return __ip_make_skb(sk, fl4, &queue, &cork);
1440 }
1441
1442 /*
1443 * Fetch data from kernel space and fill in checksum if needed.
1444 */
ip_reply_glue_bits(void * dptr,char * to,int offset,int len,int odd,struct sk_buff * skb)1445 static int ip_reply_glue_bits(void *dptr, char *to, int offset,
1446 int len, int odd, struct sk_buff *skb)
1447 {
1448 __wsum csum;
1449
1450 csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0);
1451 skb->csum = csum_block_add(skb->csum, csum, odd);
1452 return 0;
1453 }
1454
1455 /*
1456 * Generic function to send a packet as reply to another packet.
1457 * Used to send some TCP resets/acks so far.
1458 */
ip_send_unicast_reply(struct sock * sk,struct sk_buff * skb,__be32 daddr,__be32 saddr,const struct ip_reply_arg * arg,unsigned int len)1459 void ip_send_unicast_reply(struct sock *sk, struct sk_buff *skb, __be32 daddr,
1460 __be32 saddr, const struct ip_reply_arg *arg,
1461 unsigned int len)
1462 {
1463 struct ip_options_data replyopts;
1464 struct ipcm_cookie ipc;
1465 struct flowi4 fl4;
1466 struct rtable *rt = skb_rtable(skb);
1467 struct net *net = sock_net(sk);
1468 struct sk_buff *nskb;
1469 int err;
1470
1471 if (ip_options_echo(&replyopts.opt.opt, skb))
1472 return;
1473
1474 ipc.addr = daddr;
1475 ipc.opt = NULL;
1476 ipc.tx_flags = 0;
1477
1478 if (replyopts.opt.opt.optlen) {
1479 ipc.opt = &replyopts.opt;
1480
1481 if (replyopts.opt.opt.srr)
1482 daddr = replyopts.opt.opt.faddr;
1483 }
1484
1485 flowi4_init_output(&fl4, arg->bound_dev_if,
1486 IP4_REPLY_MARK(net, skb->mark),
1487 RT_TOS(arg->tos),
1488 RT_SCOPE_UNIVERSE, ip_hdr(skb)->protocol,
1489 ip_reply_arg_flowi_flags(arg),
1490 daddr, saddr,
1491 tcp_hdr(skb)->source, tcp_hdr(skb)->dest,
1492 arg->uid);
1493 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
1494 rt = ip_route_output_key(net, &fl4);
1495 if (IS_ERR(rt))
1496 return;
1497
1498 inet_sk(sk)->tos = arg->tos;
1499
1500 sk->sk_priority = skb->priority;
1501 sk->sk_protocol = ip_hdr(skb)->protocol;
1502 sk->sk_bound_dev_if = arg->bound_dev_if;
1503 sk->sk_sndbuf = sysctl_wmem_default;
1504 err = ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base,
1505 len, 0, &ipc, &rt, MSG_DONTWAIT);
1506 if (unlikely(err)) {
1507 ip_flush_pending_frames(sk);
1508 goto out;
1509 }
1510
1511 nskb = skb_peek(&sk->sk_write_queue);
1512 if (nskb) {
1513 if (arg->csumoffset >= 0)
1514 *((__sum16 *)skb_transport_header(nskb) +
1515 arg->csumoffset) = csum_fold(csum_add(nskb->csum,
1516 arg->csum));
1517 nskb->ip_summed = CHECKSUM_NONE;
1518 skb_set_queue_mapping(nskb, skb_get_queue_mapping(skb));
1519 ip_push_pending_frames(sk, &fl4);
1520 }
1521 out:
1522 ip_rt_put(rt);
1523 }
1524
ip_init(void)1525 void __init ip_init(void)
1526 {
1527 ip_rt_init();
1528 inet_initpeers();
1529
1530 #if defined(CONFIG_IP_MULTICAST) && defined(CONFIG_PROC_FS)
1531 igmp_mc_proc_init();
1532 #endif
1533 }
1534