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 <asm/system.h>
47 #include <linux/module.h>
48 #include <linux/types.h>
49 #include <linux/kernel.h>
50 #include <linux/mm.h>
51 #include <linux/string.h>
52 #include <linux/errno.h>
53 #include <linux/highmem.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
85 /* Generate a checksum for an outgoing IP datagram. */
ip_send_check(struct iphdr * iph)86 __inline__ void ip_send_check(struct iphdr *iph)
87 {
88 iph->check = 0;
89 iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
90 }
91
__ip_local_out(struct sk_buff * skb)92 int __ip_local_out(struct sk_buff *skb)
93 {
94 struct iphdr *iph = ip_hdr(skb);
95
96 iph->tot_len = htons(skb->len);
97 ip_send_check(iph);
98 return nf_hook(PF_INET, NF_INET_LOCAL_OUT, skb, NULL, skb->dst->dev,
99 dst_output);
100 }
101
ip_local_out(struct sk_buff * skb)102 int ip_local_out(struct sk_buff *skb)
103 {
104 int err;
105
106 err = __ip_local_out(skb);
107 if (likely(err == 1))
108 err = dst_output(skb);
109
110 return err;
111 }
112 EXPORT_SYMBOL_GPL(ip_local_out);
113
114 /* dev_loopback_xmit for use with netfilter. */
ip_dev_loopback_xmit(struct sk_buff * newskb)115 static int ip_dev_loopback_xmit(struct sk_buff *newskb)
116 {
117 skb_reset_mac_header(newskb);
118 __skb_pull(newskb, skb_network_offset(newskb));
119 newskb->pkt_type = PACKET_LOOPBACK;
120 newskb->ip_summed = CHECKSUM_UNNECESSARY;
121 WARN_ON(!newskb->dst);
122 netif_rx(newskb);
123 return 0;
124 }
125
ip_select_ttl(struct inet_sock * inet,struct dst_entry * dst)126 static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst)
127 {
128 int ttl = inet->uc_ttl;
129
130 if (ttl < 0)
131 ttl = dst_metric(dst, RTAX_HOPLIMIT);
132 return ttl;
133 }
134
135 /*
136 * Add an ip header to a skbuff and send it out.
137 *
138 */
ip_build_and_send_pkt(struct sk_buff * skb,struct sock * sk,__be32 saddr,__be32 daddr,struct ip_options * opt)139 int ip_build_and_send_pkt(struct sk_buff *skb, struct sock *sk,
140 __be32 saddr, __be32 daddr, struct ip_options *opt)
141 {
142 struct inet_sock *inet = inet_sk(sk);
143 struct rtable *rt = skb->rtable;
144 struct iphdr *iph;
145
146 /* Build the IP header. */
147 skb_push(skb, sizeof(struct iphdr) + (opt ? opt->optlen : 0));
148 skb_reset_network_header(skb);
149 iph = ip_hdr(skb);
150 iph->version = 4;
151 iph->ihl = 5;
152 iph->tos = inet->tos;
153 if (ip_dont_fragment(sk, &rt->u.dst))
154 iph->frag_off = htons(IP_DF);
155 else
156 iph->frag_off = 0;
157 iph->ttl = ip_select_ttl(inet, &rt->u.dst);
158 iph->daddr = rt->rt_dst;
159 iph->saddr = rt->rt_src;
160 iph->protocol = sk->sk_protocol;
161 ip_select_ident(iph, &rt->u.dst, sk);
162
163 if (opt && opt->optlen) {
164 iph->ihl += opt->optlen>>2;
165 ip_options_build(skb, opt, daddr, rt, 0);
166 }
167
168 skb->priority = sk->sk_priority;
169 skb->mark = sk->sk_mark;
170
171 /* Send it out. */
172 return ip_local_out(skb);
173 }
174
175 EXPORT_SYMBOL_GPL(ip_build_and_send_pkt);
176
ip_finish_output2(struct sk_buff * skb)177 static inline int ip_finish_output2(struct sk_buff *skb)
178 {
179 struct dst_entry *dst = skb->dst;
180 struct rtable *rt = (struct rtable *)dst;
181 struct net_device *dev = dst->dev;
182 unsigned int hh_len = LL_RESERVED_SPACE(dev);
183
184 if (rt->rt_type == RTN_MULTICAST)
185 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_OUTMCASTPKTS);
186 else if (rt->rt_type == RTN_BROADCAST)
187 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_OUTBCASTPKTS);
188
189 /* Be paranoid, rather than too clever. */
190 if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) {
191 struct sk_buff *skb2;
192
193 skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev));
194 if (skb2 == NULL) {
195 kfree_skb(skb);
196 return -ENOMEM;
197 }
198 if (skb->sk)
199 skb_set_owner_w(skb2, skb->sk);
200 kfree_skb(skb);
201 skb = skb2;
202 }
203
204 if (dst->hh)
205 return neigh_hh_output(dst->hh, skb);
206 else if (dst->neighbour)
207 return dst->neighbour->output(skb);
208
209 if (net_ratelimit())
210 printk(KERN_DEBUG "ip_finish_output2: No header cache and no neighbour!\n");
211 kfree_skb(skb);
212 return -EINVAL;
213 }
214
ip_skb_dst_mtu(struct sk_buff * skb)215 static inline int ip_skb_dst_mtu(struct sk_buff *skb)
216 {
217 struct inet_sock *inet = skb->sk ? inet_sk(skb->sk) : NULL;
218
219 return (inet && inet->pmtudisc == IP_PMTUDISC_PROBE) ?
220 skb->dst->dev->mtu : dst_mtu(skb->dst);
221 }
222
ip_finish_output(struct sk_buff * skb)223 static int ip_finish_output(struct sk_buff *skb)
224 {
225 #if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
226 /* Policy lookup after SNAT yielded a new policy */
227 if (skb->dst->xfrm != NULL) {
228 IPCB(skb)->flags |= IPSKB_REROUTED;
229 return dst_output(skb);
230 }
231 #endif
232 if (skb->len > ip_skb_dst_mtu(skb) && !skb_is_gso(skb))
233 return ip_fragment(skb, ip_finish_output2);
234 else
235 return ip_finish_output2(skb);
236 }
237
ip_mc_output(struct sk_buff * skb)238 int ip_mc_output(struct sk_buff *skb)
239 {
240 struct sock *sk = skb->sk;
241 struct rtable *rt = skb->rtable;
242 struct net_device *dev = rt->u.dst.dev;
243
244 /*
245 * If the indicated interface is up and running, send the packet.
246 */
247 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_OUTREQUESTS);
248
249 skb->dev = dev;
250 skb->protocol = htons(ETH_P_IP);
251
252 /*
253 * Multicasts are looped back for other local users
254 */
255
256 if (rt->rt_flags&RTCF_MULTICAST) {
257 if ((!sk || inet_sk(sk)->mc_loop)
258 #ifdef CONFIG_IP_MROUTE
259 /* Small optimization: do not loopback not local frames,
260 which returned after forwarding; they will be dropped
261 by ip_mr_input in any case.
262 Note, that local frames are looped back to be delivered
263 to local recipients.
264
265 This check is duplicated in ip_mr_input at the moment.
266 */
267 && ((rt->rt_flags&RTCF_LOCAL) || !(IPCB(skb)->flags&IPSKB_FORWARDED))
268 #endif
269 ) {
270 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
271 if (newskb)
272 NF_HOOK(PF_INET, NF_INET_POST_ROUTING, newskb,
273 NULL, newskb->dev,
274 ip_dev_loopback_xmit);
275 }
276
277 /* Multicasts with ttl 0 must not go beyond the host */
278
279 if (ip_hdr(skb)->ttl == 0) {
280 kfree_skb(skb);
281 return 0;
282 }
283 }
284
285 if (rt->rt_flags&RTCF_BROADCAST) {
286 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
287 if (newskb)
288 NF_HOOK(PF_INET, NF_INET_POST_ROUTING, newskb, NULL,
289 newskb->dev, ip_dev_loopback_xmit);
290 }
291
292 return NF_HOOK_COND(PF_INET, NF_INET_POST_ROUTING, skb, NULL, skb->dev,
293 ip_finish_output,
294 !(IPCB(skb)->flags & IPSKB_REROUTED));
295 }
296
ip_output(struct sk_buff * skb)297 int ip_output(struct sk_buff *skb)
298 {
299 struct net_device *dev = skb->dst->dev;
300
301 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_OUTREQUESTS);
302
303 skb->dev = dev;
304 skb->protocol = htons(ETH_P_IP);
305
306 return NF_HOOK_COND(PF_INET, NF_INET_POST_ROUTING, skb, NULL, dev,
307 ip_finish_output,
308 !(IPCB(skb)->flags & IPSKB_REROUTED));
309 }
310
ip_queue_xmit(struct sk_buff * skb,int ipfragok)311 int ip_queue_xmit(struct sk_buff *skb, int ipfragok)
312 {
313 struct sock *sk = skb->sk;
314 struct inet_sock *inet = inet_sk(sk);
315 struct ip_options *opt = inet->opt;
316 struct rtable *rt;
317 struct iphdr *iph;
318
319 /* Skip all of this if the packet is already routed,
320 * f.e. by something like SCTP.
321 */
322 rt = skb->rtable;
323 if (rt != NULL)
324 goto packet_routed;
325
326 /* Make sure we can route this packet. */
327 rt = (struct rtable *)__sk_dst_check(sk, 0);
328 if (rt == NULL) {
329 __be32 daddr;
330
331 /* Use correct destination address if we have options. */
332 daddr = inet->daddr;
333 if(opt && opt->srr)
334 daddr = opt->faddr;
335
336 {
337 struct flowi fl = { .oif = sk->sk_bound_dev_if,
338 .nl_u = { .ip4_u =
339 { .daddr = daddr,
340 .saddr = inet->saddr,
341 .tos = RT_CONN_FLAGS(sk) } },
342 .proto = sk->sk_protocol,
343 .flags = inet_sk_flowi_flags(sk),
344 .uli_u = { .ports =
345 { .sport = inet->sport,
346 .dport = inet->dport } } };
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 security_sk_classify_flow(sk, &fl);
353 if (ip_route_output_flow(sock_net(sk), &rt, &fl, sk, 0))
354 goto no_route;
355 }
356 sk_setup_caps(sk, &rt->u.dst);
357 }
358 skb->dst = dst_clone(&rt->u.dst);
359
360 packet_routed:
361 if (opt && opt->is_strictroute && rt->rt_dst != rt->rt_gateway)
362 goto no_route;
363
364 /* OK, we know where to send it, allocate and build IP header. */
365 skb_push(skb, sizeof(struct iphdr) + (opt ? opt->optlen : 0));
366 skb_reset_network_header(skb);
367 iph = ip_hdr(skb);
368 *((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (inet->tos & 0xff));
369 if (ip_dont_fragment(sk, &rt->u.dst) && !ipfragok)
370 iph->frag_off = htons(IP_DF);
371 else
372 iph->frag_off = 0;
373 iph->ttl = ip_select_ttl(inet, &rt->u.dst);
374 iph->protocol = sk->sk_protocol;
375 iph->saddr = rt->rt_src;
376 iph->daddr = rt->rt_dst;
377 /* Transport layer set skb->h.foo itself. */
378
379 if (opt && opt->optlen) {
380 iph->ihl += opt->optlen >> 2;
381 ip_options_build(skb, opt, inet->daddr, rt, 0);
382 }
383
384 ip_select_ident_more(iph, &rt->u.dst, sk,
385 (skb_shinfo(skb)->gso_segs ?: 1) - 1);
386
387 skb->priority = sk->sk_priority;
388 skb->mark = sk->sk_mark;
389
390 return ip_local_out(skb);
391
392 no_route:
393 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
394 kfree_skb(skb);
395 return -EHOSTUNREACH;
396 }
397
398
ip_copy_metadata(struct sk_buff * to,struct sk_buff * from)399 static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from)
400 {
401 to->pkt_type = from->pkt_type;
402 to->priority = from->priority;
403 to->protocol = from->protocol;
404 dst_release(to->dst);
405 to->dst = dst_clone(from->dst);
406 to->dev = from->dev;
407 to->mark = from->mark;
408
409 /* Copy the flags to each fragment. */
410 IPCB(to)->flags = IPCB(from)->flags;
411
412 #ifdef CONFIG_NET_SCHED
413 to->tc_index = from->tc_index;
414 #endif
415 nf_copy(to, from);
416 #if defined(CONFIG_NETFILTER_XT_TARGET_TRACE) || \
417 defined(CONFIG_NETFILTER_XT_TARGET_TRACE_MODULE)
418 to->nf_trace = from->nf_trace;
419 #endif
420 #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
421 to->ipvs_property = from->ipvs_property;
422 #endif
423 skb_copy_secmark(to, from);
424 }
425
426 /*
427 * This IP datagram is too large to be sent in one piece. Break it up into
428 * smaller pieces (each of size equal to IP header plus
429 * a block of the data of the original IP data part) that will yet fit in a
430 * single device frame, and queue such a frame for sending.
431 */
432
ip_fragment(struct sk_buff * skb,int (* output)(struct sk_buff *))433 int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *))
434 {
435 struct iphdr *iph;
436 int raw = 0;
437 int ptr;
438 struct net_device *dev;
439 struct sk_buff *skb2;
440 unsigned int mtu, hlen, left, len, ll_rs, pad;
441 int offset;
442 __be16 not_last_frag;
443 struct rtable *rt = skb->rtable;
444 int err = 0;
445
446 dev = rt->u.dst.dev;
447
448 /*
449 * Point into the IP datagram header.
450 */
451
452 iph = ip_hdr(skb);
453
454 if (unlikely((iph->frag_off & htons(IP_DF)) && !skb->local_df)) {
455 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
456 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
457 htonl(ip_skb_dst_mtu(skb)));
458 kfree_skb(skb);
459 return -EMSGSIZE;
460 }
461
462 /*
463 * Setup starting values.
464 */
465
466 hlen = iph->ihl * 4;
467 mtu = dst_mtu(&rt->u.dst) - hlen; /* Size of data space */
468 IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE;
469
470 /* When frag_list is given, use it. First, check its validity:
471 * some transformers could create wrong frag_list or break existing
472 * one, it is not prohibited. In this case fall back to copying.
473 *
474 * LATER: this step can be merged to real generation of fragments,
475 * we can switch to copy when see the first bad fragment.
476 */
477 if (skb_shinfo(skb)->frag_list) {
478 struct sk_buff *frag;
479 int first_len = skb_pagelen(skb);
480 int truesizes = 0;
481
482 if (first_len - hlen > mtu ||
483 ((first_len - hlen) & 7) ||
484 (iph->frag_off & htons(IP_MF|IP_OFFSET)) ||
485 skb_cloned(skb))
486 goto slow_path;
487
488 for (frag = skb_shinfo(skb)->frag_list; frag; frag = frag->next) {
489 /* Correct geometry. */
490 if (frag->len > mtu ||
491 ((frag->len & 7) && frag->next) ||
492 skb_headroom(frag) < hlen)
493 goto slow_path;
494
495 /* Partially cloned skb? */
496 if (skb_shared(frag))
497 goto slow_path;
498
499 BUG_ON(frag->sk);
500 if (skb->sk) {
501 sock_hold(skb->sk);
502 frag->sk = skb->sk;
503 frag->destructor = sock_wfree;
504 truesizes += frag->truesize;
505 }
506 }
507
508 /* Everything is OK. Generate! */
509
510 err = 0;
511 offset = 0;
512 frag = skb_shinfo(skb)->frag_list;
513 skb_shinfo(skb)->frag_list = NULL;
514 skb->data_len = first_len - skb_headlen(skb);
515 skb->truesize -= truesizes;
516 skb->len = first_len;
517 iph->tot_len = htons(first_len);
518 iph->frag_off = htons(IP_MF);
519 ip_send_check(iph);
520
521 for (;;) {
522 /* Prepare header of the next frame,
523 * before previous one went down. */
524 if (frag) {
525 frag->ip_summed = CHECKSUM_NONE;
526 skb_reset_transport_header(frag);
527 __skb_push(frag, hlen);
528 skb_reset_network_header(frag);
529 memcpy(skb_network_header(frag), iph, hlen);
530 iph = ip_hdr(frag);
531 iph->tot_len = htons(frag->len);
532 ip_copy_metadata(frag, skb);
533 if (offset == 0)
534 ip_options_fragment(frag);
535 offset += skb->len - hlen;
536 iph->frag_off = htons(offset>>3);
537 if (frag->next != NULL)
538 iph->frag_off |= htons(IP_MF);
539 /* Ready, complete checksum */
540 ip_send_check(iph);
541 }
542
543 err = output(skb);
544
545 if (!err)
546 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES);
547 if (err || !frag)
548 break;
549
550 skb = frag;
551 frag = skb->next;
552 skb->next = NULL;
553 }
554
555 if (err == 0) {
556 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS);
557 return 0;
558 }
559
560 while (frag) {
561 skb = frag->next;
562 kfree_skb(frag);
563 frag = skb;
564 }
565 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
566 return err;
567 }
568
569 slow_path:
570 left = skb->len - hlen; /* Space per frame */
571 ptr = raw + hlen; /* Where to start from */
572
573 /* for bridged IP traffic encapsulated inside f.e. a vlan header,
574 * we need to make room for the encapsulating header
575 */
576 pad = nf_bridge_pad(skb);
577 ll_rs = LL_RESERVED_SPACE_EXTRA(rt->u.dst.dev, pad);
578 mtu -= pad;
579
580 /*
581 * Fragment the datagram.
582 */
583
584 offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3;
585 not_last_frag = iph->frag_off & htons(IP_MF);
586
587 /*
588 * Keep copying data until we run out.
589 */
590
591 while (left > 0) {
592 len = left;
593 /* IF: it doesn't fit, use 'mtu' - the data space left */
594 if (len > mtu)
595 len = mtu;
596 /* IF: we are not sending upto and including the packet end
597 then align the next start on an eight byte boundary */
598 if (len < left) {
599 len &= ~7;
600 }
601 /*
602 * Allocate buffer.
603 */
604
605 if ((skb2 = alloc_skb(len+hlen+ll_rs, GFP_ATOMIC)) == NULL) {
606 NETDEBUG(KERN_INFO "IP: frag: no memory for new fragment!\n");
607 err = -ENOMEM;
608 goto fail;
609 }
610
611 /*
612 * Set up data on packet
613 */
614
615 ip_copy_metadata(skb2, skb);
616 skb_reserve(skb2, ll_rs);
617 skb_put(skb2, len + hlen);
618 skb_reset_network_header(skb2);
619 skb2->transport_header = skb2->network_header + hlen;
620
621 /*
622 * Charge the memory for the fragment to any owner
623 * it might possess
624 */
625
626 if (skb->sk)
627 skb_set_owner_w(skb2, skb->sk);
628
629 /*
630 * Copy the packet header into the new buffer.
631 */
632
633 skb_copy_from_linear_data(skb, skb_network_header(skb2), hlen);
634
635 /*
636 * Copy a block of the IP datagram.
637 */
638 if (skb_copy_bits(skb, ptr, skb_transport_header(skb2), len))
639 BUG();
640 left -= len;
641
642 /*
643 * Fill in the new header fields.
644 */
645 iph = ip_hdr(skb2);
646 iph->frag_off = htons((offset >> 3));
647
648 /* ANK: dirty, but effective trick. Upgrade options only if
649 * the segment to be fragmented was THE FIRST (otherwise,
650 * options are already fixed) and make it ONCE
651 * on the initial skb, so that all the following fragments
652 * will inherit fixed options.
653 */
654 if (offset == 0)
655 ip_options_fragment(skb);
656
657 /*
658 * Added AC : If we are fragmenting a fragment that's not the
659 * last fragment then keep MF on each bit
660 */
661 if (left > 0 || not_last_frag)
662 iph->frag_off |= htons(IP_MF);
663 ptr += len;
664 offset += len;
665
666 /*
667 * Put this fragment into the sending queue.
668 */
669 iph->tot_len = htons(len + hlen);
670
671 ip_send_check(iph);
672
673 err = output(skb2);
674 if (err)
675 goto fail;
676
677 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES);
678 }
679 kfree_skb(skb);
680 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS);
681 return err;
682
683 fail:
684 kfree_skb(skb);
685 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
686 return err;
687 }
688
689 EXPORT_SYMBOL(ip_fragment);
690
691 int
ip_generic_getfrag(void * from,char * to,int offset,int len,int odd,struct sk_buff * skb)692 ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
693 {
694 struct iovec *iov = from;
695
696 if (skb->ip_summed == CHECKSUM_PARTIAL) {
697 if (memcpy_fromiovecend(to, iov, offset, len) < 0)
698 return -EFAULT;
699 } else {
700 __wsum csum = 0;
701 if (csum_partial_copy_fromiovecend(to, iov, offset, len, &csum) < 0)
702 return -EFAULT;
703 skb->csum = csum_block_add(skb->csum, csum, odd);
704 }
705 return 0;
706 }
707
708 static inline __wsum
csum_page(struct page * page,int offset,int copy)709 csum_page(struct page *page, int offset, int copy)
710 {
711 char *kaddr;
712 __wsum csum;
713 kaddr = kmap(page);
714 csum = csum_partial(kaddr + offset, copy, 0);
715 kunmap(page);
716 return csum;
717 }
718
ip_ufo_append_data(struct sock * sk,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 mtu,unsigned int flags)719 static inline int ip_ufo_append_data(struct sock *sk,
720 int getfrag(void *from, char *to, int offset, int len,
721 int odd, struct sk_buff *skb),
722 void *from, int length, int hh_len, int fragheaderlen,
723 int transhdrlen, int mtu, unsigned int flags)
724 {
725 struct sk_buff *skb;
726 int err;
727
728 /* There is support for UDP fragmentation offload by network
729 * device, so create one single skb packet containing complete
730 * udp datagram
731 */
732 if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL) {
733 skb = sock_alloc_send_skb(sk,
734 hh_len + fragheaderlen + transhdrlen + 20,
735 (flags & MSG_DONTWAIT), &err);
736
737 if (skb == NULL)
738 return err;
739
740 /* reserve space for Hardware header */
741 skb_reserve(skb, hh_len);
742
743 /* create space for UDP/IP header */
744 skb_put(skb, fragheaderlen + transhdrlen);
745
746 /* initialize network header pointer */
747 skb_reset_network_header(skb);
748
749 /* initialize protocol header pointer */
750 skb->transport_header = skb->network_header + fragheaderlen;
751
752 skb->ip_summed = CHECKSUM_PARTIAL;
753 skb->csum = 0;
754 sk->sk_sndmsg_off = 0;
755
756 /* specify the length of each IP datagram fragment */
757 skb_shinfo(skb)->gso_size = mtu - fragheaderlen;
758 skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
759 __skb_queue_tail(&sk->sk_write_queue, skb);
760 }
761
762 return skb_append_datato_frags(sk, skb, getfrag, from,
763 (length - transhdrlen));
764 }
765
766 /*
767 * ip_append_data() and ip_append_page() can make one large IP datagram
768 * from many pieces of data. Each pieces will be holded on the socket
769 * until ip_push_pending_frames() is called. Each piece can be a page
770 * or non-page data.
771 *
772 * Not only UDP, other transport protocols - e.g. raw sockets - can use
773 * this interface potentially.
774 *
775 * LATER: length must be adjusted by pad at tail, when it is required.
776 */
ip_append_data(struct sock * sk,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)777 int ip_append_data(struct sock *sk,
778 int getfrag(void *from, char *to, int offset, int len,
779 int odd, struct sk_buff *skb),
780 void *from, int length, int transhdrlen,
781 struct ipcm_cookie *ipc, struct rtable **rtp,
782 unsigned int flags)
783 {
784 struct inet_sock *inet = inet_sk(sk);
785 struct sk_buff *skb;
786
787 struct ip_options *opt = NULL;
788 int hh_len;
789 int exthdrlen;
790 int mtu;
791 int copy;
792 int err;
793 int offset = 0;
794 unsigned int maxfraglen, fragheaderlen;
795 int csummode = CHECKSUM_NONE;
796 struct rtable *rt;
797
798 if (flags&MSG_PROBE)
799 return 0;
800
801 if (skb_queue_empty(&sk->sk_write_queue)) {
802 /*
803 * setup for corking.
804 */
805 opt = ipc->opt;
806 if (opt) {
807 if (inet->cork.opt == NULL) {
808 inet->cork.opt = kmalloc(sizeof(struct ip_options) + 40, sk->sk_allocation);
809 if (unlikely(inet->cork.opt == NULL))
810 return -ENOBUFS;
811 }
812 memcpy(inet->cork.opt, opt, sizeof(struct ip_options)+opt->optlen);
813 inet->cork.flags |= IPCORK_OPT;
814 inet->cork.addr = ipc->addr;
815 }
816 rt = *rtp;
817 /*
818 * We steal reference to this route, caller should not release it
819 */
820 *rtp = NULL;
821 inet->cork.fragsize = mtu = inet->pmtudisc == IP_PMTUDISC_PROBE ?
822 rt->u.dst.dev->mtu :
823 dst_mtu(rt->u.dst.path);
824 inet->cork.dst = &rt->u.dst;
825 inet->cork.length = 0;
826 sk->sk_sndmsg_page = NULL;
827 sk->sk_sndmsg_off = 0;
828 if ((exthdrlen = rt->u.dst.header_len) != 0) {
829 length += exthdrlen;
830 transhdrlen += exthdrlen;
831 }
832 } else {
833 rt = (struct rtable *)inet->cork.dst;
834 if (inet->cork.flags & IPCORK_OPT)
835 opt = inet->cork.opt;
836
837 transhdrlen = 0;
838 exthdrlen = 0;
839 mtu = inet->cork.fragsize;
840 }
841 hh_len = LL_RESERVED_SPACE(rt->u.dst.dev);
842
843 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
844 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
845
846 if (inet->cork.length + length > 0xFFFF - fragheaderlen) {
847 ip_local_error(sk, EMSGSIZE, rt->rt_dst, inet->dport, mtu-exthdrlen);
848 return -EMSGSIZE;
849 }
850
851 /*
852 * transhdrlen > 0 means that this is the first fragment and we wish
853 * it won't be fragmented in the future.
854 */
855 if (transhdrlen &&
856 length + fragheaderlen <= mtu &&
857 rt->u.dst.dev->features & NETIF_F_V4_CSUM &&
858 !exthdrlen)
859 csummode = CHECKSUM_PARTIAL;
860
861 inet->cork.length += length;
862 if (((length> mtu) || !skb_queue_empty(&sk->sk_write_queue)) &&
863 (sk->sk_protocol == IPPROTO_UDP) &&
864 (rt->u.dst.dev->features & NETIF_F_UFO)) {
865 err = ip_ufo_append_data(sk, getfrag, from, length, hh_len,
866 fragheaderlen, transhdrlen, mtu,
867 flags);
868 if (err)
869 goto error;
870 return 0;
871 }
872
873 /* So, what's going on in the loop below?
874 *
875 * We use calculated fragment length to generate chained skb,
876 * each of segments is IP fragment ready for sending to network after
877 * adding appropriate IP header.
878 */
879
880 if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL)
881 goto alloc_new_skb;
882
883 while (length > 0) {
884 /* Check if the remaining data fits into current packet. */
885 copy = mtu - skb->len;
886 if (copy < length)
887 copy = maxfraglen - skb->len;
888 if (copy <= 0) {
889 char *data;
890 unsigned int datalen;
891 unsigned int fraglen;
892 unsigned int fraggap;
893 unsigned int alloclen;
894 struct sk_buff *skb_prev;
895 alloc_new_skb:
896 skb_prev = skb;
897 if (skb_prev)
898 fraggap = skb_prev->len - maxfraglen;
899 else
900 fraggap = 0;
901
902 /*
903 * If remaining data exceeds the mtu,
904 * we know we need more fragment(s).
905 */
906 datalen = length + fraggap;
907 if (datalen > mtu - fragheaderlen)
908 datalen = maxfraglen - fragheaderlen;
909 fraglen = datalen + fragheaderlen;
910
911 if ((flags & MSG_MORE) &&
912 !(rt->u.dst.dev->features&NETIF_F_SG))
913 alloclen = mtu;
914 else
915 alloclen = datalen + fragheaderlen;
916
917 /* The last fragment gets additional space at tail.
918 * Note, with MSG_MORE we overallocate on fragments,
919 * because we have no idea what fragment will be
920 * the last.
921 */
922 if (datalen == length + fraggap)
923 alloclen += rt->u.dst.trailer_len;
924
925 if (transhdrlen) {
926 skb = sock_alloc_send_skb(sk,
927 alloclen + hh_len + 15,
928 (flags & MSG_DONTWAIT), &err);
929 } else {
930 skb = NULL;
931 if (atomic_read(&sk->sk_wmem_alloc) <=
932 2 * sk->sk_sndbuf)
933 skb = sock_wmalloc(sk,
934 alloclen + hh_len + 15, 1,
935 sk->sk_allocation);
936 if (unlikely(skb == NULL))
937 err = -ENOBUFS;
938 }
939 if (skb == NULL)
940 goto error;
941
942 /*
943 * Fill in the control structures
944 */
945 skb->ip_summed = csummode;
946 skb->csum = 0;
947 skb_reserve(skb, hh_len);
948
949 /*
950 * Find where to start putting bytes.
951 */
952 data = skb_put(skb, fraglen);
953 skb_set_network_header(skb, exthdrlen);
954 skb->transport_header = (skb->network_header +
955 fragheaderlen);
956 data += fragheaderlen;
957
958 if (fraggap) {
959 skb->csum = skb_copy_and_csum_bits(
960 skb_prev, maxfraglen,
961 data + transhdrlen, fraggap, 0);
962 skb_prev->csum = csum_sub(skb_prev->csum,
963 skb->csum);
964 data += fraggap;
965 pskb_trim_unique(skb_prev, maxfraglen);
966 }
967
968 copy = datalen - transhdrlen - fraggap;
969 if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) {
970 err = -EFAULT;
971 kfree_skb(skb);
972 goto error;
973 }
974
975 offset += copy;
976 length -= datalen - fraggap;
977 transhdrlen = 0;
978 exthdrlen = 0;
979 csummode = CHECKSUM_NONE;
980
981 /*
982 * Put the packet on the pending queue.
983 */
984 __skb_queue_tail(&sk->sk_write_queue, skb);
985 continue;
986 }
987
988 if (copy > length)
989 copy = length;
990
991 if (!(rt->u.dst.dev->features&NETIF_F_SG)) {
992 unsigned int off;
993
994 off = skb->len;
995 if (getfrag(from, skb_put(skb, copy),
996 offset, copy, off, skb) < 0) {
997 __skb_trim(skb, off);
998 err = -EFAULT;
999 goto error;
1000 }
1001 } else {
1002 int i = skb_shinfo(skb)->nr_frags;
1003 skb_frag_t *frag = &skb_shinfo(skb)->frags[i-1];
1004 struct page *page = sk->sk_sndmsg_page;
1005 int off = sk->sk_sndmsg_off;
1006 unsigned int left;
1007
1008 if (page && (left = PAGE_SIZE - off) > 0) {
1009 if (copy >= left)
1010 copy = left;
1011 if (page != frag->page) {
1012 if (i == MAX_SKB_FRAGS) {
1013 err = -EMSGSIZE;
1014 goto error;
1015 }
1016 get_page(page);
1017 skb_fill_page_desc(skb, i, page, sk->sk_sndmsg_off, 0);
1018 frag = &skb_shinfo(skb)->frags[i];
1019 }
1020 } else if (i < MAX_SKB_FRAGS) {
1021 if (copy > PAGE_SIZE)
1022 copy = PAGE_SIZE;
1023 page = alloc_pages(sk->sk_allocation, 0);
1024 if (page == NULL) {
1025 err = -ENOMEM;
1026 goto error;
1027 }
1028 sk->sk_sndmsg_page = page;
1029 sk->sk_sndmsg_off = 0;
1030
1031 skb_fill_page_desc(skb, i, page, 0, 0);
1032 frag = &skb_shinfo(skb)->frags[i];
1033 } else {
1034 err = -EMSGSIZE;
1035 goto error;
1036 }
1037 if (getfrag(from, page_address(frag->page)+frag->page_offset+frag->size, offset, copy, skb->len, skb) < 0) {
1038 err = -EFAULT;
1039 goto error;
1040 }
1041 sk->sk_sndmsg_off += copy;
1042 frag->size += copy;
1043 skb->len += copy;
1044 skb->data_len += copy;
1045 skb->truesize += copy;
1046 atomic_add(copy, &sk->sk_wmem_alloc);
1047 }
1048 offset += copy;
1049 length -= copy;
1050 }
1051
1052 return 0;
1053
1054 error:
1055 inet->cork.length -= length;
1056 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1057 return err;
1058 }
1059
ip_append_page(struct sock * sk,struct page * page,int offset,size_t size,int flags)1060 ssize_t ip_append_page(struct sock *sk, struct page *page,
1061 int offset, size_t size, int flags)
1062 {
1063 struct inet_sock *inet = inet_sk(sk);
1064 struct sk_buff *skb;
1065 struct rtable *rt;
1066 struct ip_options *opt = NULL;
1067 int hh_len;
1068 int mtu;
1069 int len;
1070 int err;
1071 unsigned int maxfraglen, fragheaderlen, fraggap;
1072
1073 if (inet->hdrincl)
1074 return -EPERM;
1075
1076 if (flags&MSG_PROBE)
1077 return 0;
1078
1079 if (skb_queue_empty(&sk->sk_write_queue))
1080 return -EINVAL;
1081
1082 rt = (struct rtable *)inet->cork.dst;
1083 if (inet->cork.flags & IPCORK_OPT)
1084 opt = inet->cork.opt;
1085
1086 if (!(rt->u.dst.dev->features&NETIF_F_SG))
1087 return -EOPNOTSUPP;
1088
1089 hh_len = LL_RESERVED_SPACE(rt->u.dst.dev);
1090 mtu = inet->cork.fragsize;
1091
1092 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
1093 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
1094
1095 if (inet->cork.length + size > 0xFFFF - fragheaderlen) {
1096 ip_local_error(sk, EMSGSIZE, rt->rt_dst, inet->dport, mtu);
1097 return -EMSGSIZE;
1098 }
1099
1100 if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL)
1101 return -EINVAL;
1102
1103 inet->cork.length += size;
1104 if ((sk->sk_protocol == IPPROTO_UDP) &&
1105 (rt->u.dst.dev->features & NETIF_F_UFO)) {
1106 skb_shinfo(skb)->gso_size = mtu - fragheaderlen;
1107 skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
1108 }
1109
1110
1111 while (size > 0) {
1112 int i;
1113
1114 if (skb_is_gso(skb))
1115 len = size;
1116 else {
1117
1118 /* Check if the remaining data fits into current packet. */
1119 len = mtu - skb->len;
1120 if (len < size)
1121 len = maxfraglen - skb->len;
1122 }
1123 if (len <= 0) {
1124 struct sk_buff *skb_prev;
1125 int alloclen;
1126
1127 skb_prev = skb;
1128 fraggap = skb_prev->len - maxfraglen;
1129
1130 alloclen = fragheaderlen + hh_len + fraggap + 15;
1131 skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation);
1132 if (unlikely(!skb)) {
1133 err = -ENOBUFS;
1134 goto error;
1135 }
1136
1137 /*
1138 * Fill in the control structures
1139 */
1140 skb->ip_summed = CHECKSUM_NONE;
1141 skb->csum = 0;
1142 skb_reserve(skb, hh_len);
1143
1144 /*
1145 * Find where to start putting bytes.
1146 */
1147 skb_put(skb, fragheaderlen + fraggap);
1148 skb_reset_network_header(skb);
1149 skb->transport_header = (skb->network_header +
1150 fragheaderlen);
1151 if (fraggap) {
1152 skb->csum = skb_copy_and_csum_bits(skb_prev,
1153 maxfraglen,
1154 skb_transport_header(skb),
1155 fraggap, 0);
1156 skb_prev->csum = csum_sub(skb_prev->csum,
1157 skb->csum);
1158 pskb_trim_unique(skb_prev, maxfraglen);
1159 }
1160
1161 /*
1162 * Put the packet on the pending queue.
1163 */
1164 __skb_queue_tail(&sk->sk_write_queue, skb);
1165 continue;
1166 }
1167
1168 i = skb_shinfo(skb)->nr_frags;
1169 if (len > size)
1170 len = size;
1171 if (skb_can_coalesce(skb, i, page, offset)) {
1172 skb_shinfo(skb)->frags[i-1].size += len;
1173 } else if (i < MAX_SKB_FRAGS) {
1174 get_page(page);
1175 skb_fill_page_desc(skb, i, page, offset, len);
1176 } else {
1177 err = -EMSGSIZE;
1178 goto error;
1179 }
1180
1181 if (skb->ip_summed == CHECKSUM_NONE) {
1182 __wsum csum;
1183 csum = csum_page(page, offset, len);
1184 skb->csum = csum_block_add(skb->csum, csum, skb->len);
1185 }
1186
1187 skb->len += len;
1188 skb->data_len += len;
1189 skb->truesize += len;
1190 atomic_add(len, &sk->sk_wmem_alloc);
1191 offset += len;
1192 size -= len;
1193 }
1194 return 0;
1195
1196 error:
1197 inet->cork.length -= size;
1198 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1199 return err;
1200 }
1201
ip_cork_release(struct inet_sock * inet)1202 static void ip_cork_release(struct inet_sock *inet)
1203 {
1204 inet->cork.flags &= ~IPCORK_OPT;
1205 kfree(inet->cork.opt);
1206 inet->cork.opt = NULL;
1207 dst_release(inet->cork.dst);
1208 inet->cork.dst = NULL;
1209 }
1210
1211 /*
1212 * Combined all pending IP fragments on the socket as one IP datagram
1213 * and push them out.
1214 */
ip_push_pending_frames(struct sock * sk)1215 int ip_push_pending_frames(struct sock *sk)
1216 {
1217 struct sk_buff *skb, *tmp_skb;
1218 struct sk_buff **tail_skb;
1219 struct inet_sock *inet = inet_sk(sk);
1220 struct net *net = sock_net(sk);
1221 struct ip_options *opt = NULL;
1222 struct rtable *rt = (struct rtable *)inet->cork.dst;
1223 struct iphdr *iph;
1224 __be16 df = 0;
1225 __u8 ttl;
1226 int err = 0;
1227
1228 if ((skb = __skb_dequeue(&sk->sk_write_queue)) == NULL)
1229 goto out;
1230 tail_skb = &(skb_shinfo(skb)->frag_list);
1231
1232 /* move skb->data to ip header from ext header */
1233 if (skb->data < skb_network_header(skb))
1234 __skb_pull(skb, skb_network_offset(skb));
1235 while ((tmp_skb = __skb_dequeue(&sk->sk_write_queue)) != NULL) {
1236 __skb_pull(tmp_skb, skb_network_header_len(skb));
1237 *tail_skb = tmp_skb;
1238 tail_skb = &(tmp_skb->next);
1239 skb->len += tmp_skb->len;
1240 skb->data_len += tmp_skb->len;
1241 skb->truesize += tmp_skb->truesize;
1242 __sock_put(tmp_skb->sk);
1243 tmp_skb->destructor = NULL;
1244 tmp_skb->sk = NULL;
1245 }
1246
1247 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow
1248 * to fragment the frame generated here. No matter, what transforms
1249 * how transforms change size of the packet, it will come out.
1250 */
1251 if (inet->pmtudisc < IP_PMTUDISC_DO)
1252 skb->local_df = 1;
1253
1254 /* DF bit is set when we want to see DF on outgoing frames.
1255 * If local_df is set too, we still allow to fragment this frame
1256 * locally. */
1257 if (inet->pmtudisc >= IP_PMTUDISC_DO ||
1258 (skb->len <= dst_mtu(&rt->u.dst) &&
1259 ip_dont_fragment(sk, &rt->u.dst)))
1260 df = htons(IP_DF);
1261
1262 if (inet->cork.flags & IPCORK_OPT)
1263 opt = inet->cork.opt;
1264
1265 if (rt->rt_type == RTN_MULTICAST)
1266 ttl = inet->mc_ttl;
1267 else
1268 ttl = ip_select_ttl(inet, &rt->u.dst);
1269
1270 iph = (struct iphdr *)skb->data;
1271 iph->version = 4;
1272 iph->ihl = 5;
1273 if (opt) {
1274 iph->ihl += opt->optlen>>2;
1275 ip_options_build(skb, opt, inet->cork.addr, rt, 0);
1276 }
1277 iph->tos = inet->tos;
1278 iph->frag_off = df;
1279 ip_select_ident(iph, &rt->u.dst, sk);
1280 iph->ttl = ttl;
1281 iph->protocol = sk->sk_protocol;
1282 iph->saddr = rt->rt_src;
1283 iph->daddr = rt->rt_dst;
1284
1285 skb->priority = sk->sk_priority;
1286 skb->mark = sk->sk_mark;
1287 /*
1288 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec
1289 * on dst refcount
1290 */
1291 inet->cork.dst = NULL;
1292 skb->dst = &rt->u.dst;
1293
1294 if (iph->protocol == IPPROTO_ICMP)
1295 icmp_out_count(net, ((struct icmphdr *)
1296 skb_transport_header(skb))->type);
1297
1298 /* Netfilter gets whole the not fragmented skb. */
1299 err = ip_local_out(skb);
1300 if (err) {
1301 if (err > 0)
1302 err = inet->recverr ? net_xmit_errno(err) : 0;
1303 if (err)
1304 goto error;
1305 }
1306
1307 out:
1308 ip_cork_release(inet);
1309 return err;
1310
1311 error:
1312 IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS);
1313 goto out;
1314 }
1315
1316 /*
1317 * Throw away all pending data on the socket.
1318 */
ip_flush_pending_frames(struct sock * sk)1319 void ip_flush_pending_frames(struct sock *sk)
1320 {
1321 struct sk_buff *skb;
1322
1323 while ((skb = __skb_dequeue_tail(&sk->sk_write_queue)) != NULL)
1324 kfree_skb(skb);
1325
1326 ip_cork_release(inet_sk(sk));
1327 }
1328
1329
1330 /*
1331 * Fetch data from kernel space and fill in checksum if needed.
1332 */
ip_reply_glue_bits(void * dptr,char * to,int offset,int len,int odd,struct sk_buff * skb)1333 static int ip_reply_glue_bits(void *dptr, char *to, int offset,
1334 int len, int odd, struct sk_buff *skb)
1335 {
1336 __wsum csum;
1337
1338 csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0);
1339 skb->csum = csum_block_add(skb->csum, csum, odd);
1340 return 0;
1341 }
1342
1343 /*
1344 * Generic function to send a packet as reply to another packet.
1345 * Used to send TCP resets so far. ICMP should use this function too.
1346 *
1347 * Should run single threaded per socket because it uses the sock
1348 * structure to pass arguments.
1349 */
ip_send_reply(struct sock * sk,struct sk_buff * skb,struct ip_reply_arg * arg,unsigned int len)1350 void ip_send_reply(struct sock *sk, struct sk_buff *skb, struct ip_reply_arg *arg,
1351 unsigned int len)
1352 {
1353 struct inet_sock *inet = inet_sk(sk);
1354 struct {
1355 struct ip_options opt;
1356 char data[40];
1357 } replyopts;
1358 struct ipcm_cookie ipc;
1359 __be32 daddr;
1360 struct rtable *rt = skb->rtable;
1361
1362 if (ip_options_echo(&replyopts.opt, skb))
1363 return;
1364
1365 daddr = ipc.addr = rt->rt_src;
1366 ipc.opt = NULL;
1367
1368 if (replyopts.opt.optlen) {
1369 ipc.opt = &replyopts.opt;
1370
1371 if (ipc.opt->srr)
1372 daddr = replyopts.opt.faddr;
1373 }
1374
1375 {
1376 struct flowi fl = { .oif = arg->bound_dev_if,
1377 .nl_u = { .ip4_u =
1378 { .daddr = daddr,
1379 .saddr = rt->rt_spec_dst,
1380 .tos = RT_TOS(ip_hdr(skb)->tos) } },
1381 /* Not quite clean, but right. */
1382 .uli_u = { .ports =
1383 { .sport = tcp_hdr(skb)->dest,
1384 .dport = tcp_hdr(skb)->source } },
1385 .proto = sk->sk_protocol,
1386 .flags = ip_reply_arg_flowi_flags(arg) };
1387 security_skb_classify_flow(skb, &fl);
1388 if (ip_route_output_key(sock_net(sk), &rt, &fl))
1389 return;
1390 }
1391
1392 /* And let IP do all the hard work.
1393
1394 This chunk is not reenterable, hence spinlock.
1395 Note that it uses the fact, that this function is called
1396 with locally disabled BH and that sk cannot be already spinlocked.
1397 */
1398 bh_lock_sock(sk);
1399 inet->tos = ip_hdr(skb)->tos;
1400 sk->sk_priority = skb->priority;
1401 sk->sk_protocol = ip_hdr(skb)->protocol;
1402 sk->sk_bound_dev_if = arg->bound_dev_if;
1403 ip_append_data(sk, ip_reply_glue_bits, arg->iov->iov_base, len, 0,
1404 &ipc, &rt, MSG_DONTWAIT);
1405 if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
1406 if (arg->csumoffset >= 0)
1407 *((__sum16 *)skb_transport_header(skb) +
1408 arg->csumoffset) = csum_fold(csum_add(skb->csum,
1409 arg->csum));
1410 skb->ip_summed = CHECKSUM_NONE;
1411 ip_push_pending_frames(sk);
1412 }
1413
1414 bh_unlock_sock(sk);
1415
1416 ip_rt_put(rt);
1417 }
1418
ip_init(void)1419 void __init ip_init(void)
1420 {
1421 ip_rt_init();
1422 inet_initpeers();
1423
1424 #if defined(CONFIG_IP_MULTICAST) && defined(CONFIG_PROC_FS)
1425 igmp_mc_proc_init();
1426 #endif
1427 }
1428
1429 EXPORT_SYMBOL(ip_generic_getfrag);
1430 EXPORT_SYMBOL(ip_queue_xmit);
1431 EXPORT_SYMBOL(ip_send_check);
1432