blob: 212734ca238fa88e2bcee0eb43e13c246a5f9720 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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) module.
7 *
8 * Version: $Id: ip_input.c,v 1.55 2002/01/12 07:39:45 davem Exp $
9 *
Jesper Juhl02c30a82005-05-05 16:16:16 -070010 * Authors: Ross Biro
Linus Torvalds1da177e2005-04-16 15:20:36 -070011 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
12 * Donald Becker, <becker@super.org>
13 * Alan Cox, <Alan.Cox@linux.org>
14 * Richard Underwood
15 * Stefan Becker, <stefanb@yello.ping.de>
16 * Jorge Cwik, <jorge@laser.satlink.net>
17 * Arnt Gulbrandsen, <agulbra@nvg.unit.no>
18 *
19 *
20 * Fixes:
21 * Alan Cox : Commented a couple of minor bits of surplus code
22 * Alan Cox : Undefining IP_FORWARD doesn't include the code
23 * (just stops a compiler warning).
24 * Alan Cox : Frames with >=MAX_ROUTE record routes, strict routes or loose routes
25 * are junked rather than corrupting things.
26 * Alan Cox : Frames to bad broadcast subnets are dumped
27 * We used to process them non broadcast and
28 * boy could that cause havoc.
29 * Alan Cox : ip_forward sets the free flag on the
30 * new frame it queues. Still crap because
31 * it copies the frame but at least it
32 * doesn't eat memory too.
33 * Alan Cox : Generic queue code and memory fixes.
34 * Fred Van Kempen : IP fragment support (borrowed from NET2E)
35 * Gerhard Koerting: Forward fragmented frames correctly.
36 * Gerhard Koerting: Fixes to my fix of the above 8-).
37 * Gerhard Koerting: IP interface addressing fix.
38 * Linus Torvalds : More robustness checks
39 * Alan Cox : Even more checks: Still not as robust as it ought to be
40 * Alan Cox : Save IP header pointer for later
41 * Alan Cox : ip option setting
42 * Alan Cox : Use ip_tos/ip_ttl settings
43 * Alan Cox : Fragmentation bogosity removed
44 * (Thanks to Mark.Bush@prg.ox.ac.uk)
45 * Dmitry Gorodchanin : Send of a raw packet crash fix.
46 * Alan Cox : Silly ip bug when an overlength
47 * fragment turns up. Now frees the
48 * queue.
49 * Linus Torvalds/ : Memory leakage on fragmentation
50 * Alan Cox : handling.
51 * Gerhard Koerting: Forwarding uses IP priority hints
52 * Teemu Rantanen : Fragment problems.
53 * Alan Cox : General cleanup, comments and reformat
54 * Alan Cox : SNMP statistics
55 * Alan Cox : BSD address rule semantics. Also see
56 * UDP as there is a nasty checksum issue
57 * if you do things the wrong way.
58 * Alan Cox : Always defrag, moved IP_FORWARD to the config.in file
59 * Alan Cox : IP options adjust sk->priority.
60 * Pedro Roque : Fix mtu/length error in ip_forward.
61 * Alan Cox : Avoid ip_chk_addr when possible.
62 * Richard Underwood : IP multicasting.
63 * Alan Cox : Cleaned up multicast handlers.
64 * Alan Cox : RAW sockets demultiplex in the BSD style.
65 * Gunther Mayer : Fix the SNMP reporting typo
66 * Alan Cox : Always in group 224.0.0.1
67 * Pauline Middelink : Fast ip_checksum update when forwarding
68 * Masquerading support.
69 * Alan Cox : Multicast loopback error for 224.0.0.1
70 * Alan Cox : IP_MULTICAST_LOOP option.
71 * Alan Cox : Use notifiers.
72 * Bjorn Ekwall : Removed ip_csum (from slhc.c too)
73 * Bjorn Ekwall : Moved ip_fast_csum to ip.h (inline!)
74 * Stefan Becker : Send out ICMP HOST REDIRECT
75 * Arnt Gulbrandsen : ip_build_xmit
76 * Alan Cox : Per socket routing cache
77 * Alan Cox : Fixed routing cache, added header cache.
78 * Alan Cox : Loopback didn't work right in original ip_build_xmit - fixed it.
79 * Alan Cox : Only send ICMP_REDIRECT if src/dest are the same net.
80 * Alan Cox : Incoming IP option handling.
81 * Alan Cox : Set saddr on raw output frames as per BSD.
82 * Alan Cox : Stopped broadcast source route explosions.
83 * Alan Cox : Can disable source routing
84 * Takeshi Sone : Masquerading didn't work.
85 * Dave Bonn,Alan Cox : Faster IP forwarding whenever possible.
86 * Alan Cox : Memory leaks, tramples, misc debugging.
87 * Alan Cox : Fixed multicast (by popular demand 8))
88 * Alan Cox : Fixed forwarding (by even more popular demand 8))
89 * Alan Cox : Fixed SNMP statistics [I think]
90 * Gerhard Koerting : IP fragmentation forwarding fix
91 * Alan Cox : Device lock against page fault.
92 * Alan Cox : IP_HDRINCL facility.
93 * Werner Almesberger : Zero fragment bug
94 * Alan Cox : RAW IP frame length bug
95 * Alan Cox : Outgoing firewall on build_xmit
96 * A.N.Kuznetsov : IP_OPTIONS support throughout the kernel
97 * Alan Cox : Multicast routing hooks
98 * Jos Vos : Do accounting *before* call_in_firewall
99 * Willy Konynenberg : Transparent proxying support
100 *
101 *
102 *
103 * To Fix:
104 * IP fragmentation wants rewriting cleanly. The RFC815 algorithm is much more efficient
105 * and could be made very efficient with the addition of some virtual memory hacks to permit
106 * the allocation of a buffer that can then be 'grown' by twiddling page tables.
107 * Output fragmentation wants updating along with the buffer management to use a single
108 * interleaved copy algorithm so that fragmenting has a one copy overhead. Actual packet
109 * output should probably do its own fragmentation at the UDP/RAW layer. TCP shouldn't cause
110 * fragmentation anyway.
111 *
112 * This program is free software; you can redistribute it and/or
113 * modify it under the terms of the GNU General Public License
114 * as published by the Free Software Foundation; either version
115 * 2 of the License, or (at your option) any later version.
116 */
117
118#include <asm/system.h>
119#include <linux/module.h>
120#include <linux/types.h>
121#include <linux/kernel.h>
122#include <linux/string.h>
123#include <linux/errno.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700124
125#include <linux/net.h>
126#include <linux/socket.h>
127#include <linux/sockios.h>
128#include <linux/in.h>
129#include <linux/inet.h>
Arnaldo Carvalho de Melo14c85022005-12-27 02:43:12 -0200130#include <linux/inetdevice.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131#include <linux/netdevice.h>
132#include <linux/etherdevice.h>
133
134#include <net/snmp.h>
135#include <net/ip.h>
136#include <net/protocol.h>
137#include <net/route.h>
138#include <linux/skbuff.h>
139#include <net/sock.h>
140#include <net/arp.h>
141#include <net/icmp.h>
142#include <net/raw.h>
143#include <net/checksum.h>
144#include <linux/netfilter_ipv4.h>
145#include <net/xfrm.h>
146#include <linux/mroute.h>
147#include <linux/netlink.h>
148
149/*
150 * SNMP management statistics
151 */
152
Eric Dumazetba899662005-08-26 12:05:31 -0700153DEFINE_SNMP_STAT(struct ipstats_mib, ip_statistics) __read_mostly;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700154
155/*
156 * Process Router Attention IP option
157 */
158int ip_call_ra_chain(struct sk_buff *skb)
159{
160 struct ip_ra_chain *ra;
161 u8 protocol = skb->nh.iph->protocol;
162 struct sock *last = NULL;
163
164 read_lock(&ip_ra_lock);
165 for (ra = ip_ra_chain; ra; ra = ra->next) {
166 struct sock *sk = ra->sk;
167
168 /* If socket is bound to an interface, only report
169 * the packet if it came from that interface.
170 */
171 if (sk && inet_sk(sk)->num == protocol &&
172 (!sk->sk_bound_dev_if ||
173 sk->sk_bound_dev_if == skb->dev->ifindex)) {
174 if (skb->nh.iph->frag_off & htons(IP_MF|IP_OFFSET)) {
175 skb = ip_defrag(skb, IP_DEFRAG_CALL_RA_CHAIN);
176 if (skb == NULL) {
177 read_unlock(&ip_ra_lock);
178 return 1;
179 }
180 }
181 if (last) {
182 struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
183 if (skb2)
184 raw_rcv(last, skb2);
185 }
186 last = sk;
187 }
188 }
189
190 if (last) {
191 raw_rcv(last, skb);
192 read_unlock(&ip_ra_lock);
193 return 1;
194 }
195 read_unlock(&ip_ra_lock);
196 return 0;
197}
198
199static inline int ip_local_deliver_finish(struct sk_buff *skb)
200{
201 int ihl = skb->nh.iph->ihl*4;
202
Linus Torvalds1da177e2005-04-16 15:20:36 -0700203 __skb_pull(skb, ihl);
204
Linus Torvalds1da177e2005-04-16 15:20:36 -0700205 /* Point into the IP datagram, just past the header. */
206 skb->h.raw = skb->data;
207
208 rcu_read_lock();
209 {
210 /* Note: See raw.c and net/raw.h, RAWV4_HTABLE_SIZE==MAX_INET_PROTOS */
211 int protocol = skb->nh.iph->protocol;
212 int hash;
213 struct sock *raw_sk;
214 struct net_protocol *ipprot;
215
216 resubmit:
217 hash = protocol & (MAX_INET_PROTOS - 1);
218 raw_sk = sk_head(&raw_v4_htable[hash]);
219
220 /* If there maybe a raw socket we must check - if not we
221 * don't care less
222 */
Patrick McHardyd13964f2005-08-09 19:45:02 -0700223 if (raw_sk && !raw_v4_input(skb, skb->nh.iph, hash))
224 raw_sk = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700225
226 if ((ipprot = rcu_dereference(inet_protos[hash])) != NULL) {
227 int ret;
228
Patrick McHardyb59c2702006-01-06 23:06:10 -0800229 if (!ipprot->no_policy) {
230 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
231 kfree_skb(skb);
232 goto out;
233 }
234 nf_reset(skb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700235 }
236 ret = ipprot->handler(skb);
237 if (ret < 0) {
238 protocol = -ret;
239 goto resubmit;
240 }
241 IP_INC_STATS_BH(IPSTATS_MIB_INDELIVERS);
242 } else {
243 if (!raw_sk) {
244 if (xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
245 IP_INC_STATS_BH(IPSTATS_MIB_INUNKNOWNPROTOS);
246 icmp_send(skb, ICMP_DEST_UNREACH,
247 ICMP_PROT_UNREACH, 0);
248 }
249 } else
250 IP_INC_STATS_BH(IPSTATS_MIB_INDELIVERS);
251 kfree_skb(skb);
252 }
253 }
254 out:
255 rcu_read_unlock();
256
257 return 0;
258}
259
260/*
261 * Deliver IP Packets to the higher protocol layers.
262 */
263int ip_local_deliver(struct sk_buff *skb)
264{
265 /*
266 * Reassemble IP fragments.
267 */
268
269 if (skb->nh.iph->frag_off & htons(IP_MF|IP_OFFSET)) {
270 skb = ip_defrag(skb, IP_DEFRAG_LOCAL_DELIVER);
271 if (!skb)
272 return 0;
273 }
274
275 return NF_HOOK(PF_INET, NF_IP_LOCAL_IN, skb, skb->dev, NULL,
276 ip_local_deliver_finish);
277}
278
Thomas Grafd2454072005-08-20 17:26:12 -0700279static inline int ip_rcv_options(struct sk_buff *skb)
280{
281 struct ip_options *opt;
282 struct iphdr *iph;
283 struct net_device *dev = skb->dev;
284
285 /* It looks as overkill, because not all
286 IP options require packet mangling.
287 But it is the easiest for now, especially taking
288 into account that combination of IP options
289 and running sniffer is extremely rare condition.
290 --ANK (980813)
291 */
292 if (skb_cow(skb, skb_headroom(skb))) {
293 IP_INC_STATS_BH(IPSTATS_MIB_INDISCARDS);
294 goto drop;
295 }
296
297 iph = skb->nh.iph;
298
299 if (ip_options_compile(NULL, skb)) {
300 IP_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
301 goto drop;
302 }
303
304 opt = &(IPCB(skb)->opt);
305 if (unlikely(opt->srr)) {
306 struct in_device *in_dev = in_dev_get(dev);
307 if (in_dev) {
308 if (!IN_DEV_SOURCE_ROUTE(in_dev)) {
309 if (IN_DEV_LOG_MARTIANS(in_dev) &&
310 net_ratelimit())
311 printk(KERN_INFO "source route option "
312 "%u.%u.%u.%u -> %u.%u.%u.%u\n",
313 NIPQUAD(iph->saddr),
314 NIPQUAD(iph->daddr));
315 in_dev_put(in_dev);
316 goto drop;
317 }
318
319 in_dev_put(in_dev);
320 }
321
322 if (ip_options_rcv_srr(skb))
323 goto drop;
324 }
325
326 return 0;
327drop:
328 return -1;
329}
330
Linus Torvalds1da177e2005-04-16 15:20:36 -0700331static inline int ip_rcv_finish(struct sk_buff *skb)
332{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333 struct iphdr *iph = skb->nh.iph;
334
335 /*
336 * Initialise the virtual path cache for the packet. It describes
337 * how the packet travels inside Linux networking.
338 */
Hua Zhong0182bd22006-05-06 18:11:39 -0700339 if (skb->dst == NULL) {
Thomas Graf3e192be2005-08-20 17:26:30 -0700340 int err = ip_route_input(skb, iph->daddr, iph->saddr, iph->tos,
341 skb->dev);
342 if (unlikely(err)) {
Dietmar Eggemann2c2910a2005-06-28 13:06:23 -0700343 if (err == -EHOSTUNREACH)
344 IP_INC_STATS_BH(IPSTATS_MIB_INADDRERRORS);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700345 goto drop;
Dietmar Eggemann2c2910a2005-06-28 13:06:23 -0700346 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700347 }
348
349#ifdef CONFIG_NET_CLS_ROUTE
Thomas Graf3e192be2005-08-20 17:26:30 -0700350 if (unlikely(skb->dst->tclassid)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700351 struct ip_rt_acct *st = ip_rt_acct + 256*smp_processor_id();
352 u32 idx = skb->dst->tclassid;
353 st[idx&0xFF].o_packets++;
354 st[idx&0xFF].o_bytes+=skb->len;
355 st[(idx>>16)&0xFF].i_packets++;
356 st[(idx>>16)&0xFF].i_bytes+=skb->len;
357 }
358#endif
359
Thomas Grafd2454072005-08-20 17:26:12 -0700360 if (iph->ihl > 5 && ip_rcv_options(skb))
361 goto drop;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700362
363 return dst_input(skb);
364
Linus Torvalds1da177e2005-04-16 15:20:36 -0700365drop:
366 kfree_skb(skb);
367 return NET_RX_DROP;
368}
369
370/*
371 * Main IP Receive routine.
372 */
David S. Millerf2ccd8f2005-08-09 19:34:12 -0700373int ip_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700374{
375 struct iphdr *iph;
Thomas Graf58615242005-08-20 17:25:29 -0700376 u32 len;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700377
378 /* When the interface is in promisc. mode, drop all the crap
379 * that it receives, do not try to analyse it.
380 */
381 if (skb->pkt_type == PACKET_OTHERHOST)
382 goto drop;
383
384 IP_INC_STATS_BH(IPSTATS_MIB_INRECEIVES);
385
386 if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL) {
387 IP_INC_STATS_BH(IPSTATS_MIB_INDISCARDS);
388 goto out;
389 }
390
391 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
392 goto inhdr_error;
393
394 iph = skb->nh.iph;
395
396 /*
397 * RFC1122: 3.1.2.2 MUST silently discard any IP frame that fails the checksum.
398 *
399 * Is the datagram acceptable?
400 *
401 * 1. Length at least the size of an ip header
402 * 2. Version of 4
403 * 3. Checksums correctly. [Speed optimisation for later, skip loopback checksums]
404 * 4. Doesn't have a bogus length
405 */
406
407 if (iph->ihl < 5 || iph->version != 4)
Thomas Graf58615242005-08-20 17:25:29 -0700408 goto inhdr_error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700409
410 if (!pskb_may_pull(skb, iph->ihl*4))
411 goto inhdr_error;
412
413 iph = skb->nh.iph;
414
Thomas Grafe9c60422005-08-20 17:25:52 -0700415 if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
Thomas Graf58615242005-08-20 17:25:29 -0700416 goto inhdr_error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700417
Thomas Graf58615242005-08-20 17:25:29 -0700418 len = ntohs(iph->tot_len);
419 if (skb->len < len || len < (iph->ihl*4))
420 goto inhdr_error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700421
Thomas Graf58615242005-08-20 17:25:29 -0700422 /* Our transport medium may have padded the buffer out. Now we know it
423 * is IP we can trim to the true length of the frame.
424 * Note this now means skb->len holds ntohs(iph->tot_len).
425 */
426 if (pskb_trim_rcsum(skb, len)) {
427 IP_INC_STATS_BH(IPSTATS_MIB_INDISCARDS);
428 goto drop;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700429 }
430
Stephen Hemminger53602f92006-07-14 14:49:32 -0700431 /* Remove any debris in the socket control block */
Guillaume Chazaraind569f1d2006-07-24 23:45:16 -0700432 memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
Stephen Hemminger53602f92006-07-14 14:49:32 -0700433
Linus Torvalds1da177e2005-04-16 15:20:36 -0700434 return NF_HOOK(PF_INET, NF_IP_PRE_ROUTING, skb, dev, NULL,
435 ip_rcv_finish);
436
437inhdr_error:
438 IP_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
439drop:
440 kfree_skb(skb);
441out:
442 return NET_RX_DROP;
443}
444
Linus Torvalds1da177e2005-04-16 15:20:36 -0700445EXPORT_SYMBOL(ip_statistics);