Commit | Line | Data |
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1da177e4 LT |
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) module. | |
7 | * | |
8 | * Version: $Id: ip_input.c,v 1.55 2002/01/12 07:39:45 davem Exp $ | |
9 | * | |
02c30a84 | 10 | * Authors: Ross Biro |
1da177e4 LT |
11 | * 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> | |
1da177e4 LT |
124 | |
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> | |
14c85021 | 130 | #include <linux/inetdevice.h> |
1da177e4 LT |
131 | #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 | ||
ba89966c | 153 | DEFINE_SNMP_STAT(struct ipstats_mib, ip_statistics) __read_mostly; |
1da177e4 LT |
154 | |
155 | /* | |
156 | * Process Router Attention IP option | |
157 | */ | |
158 | int 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 | ||
199 | static inline int ip_local_deliver_finish(struct sk_buff *skb) | |
200 | { | |
201 | int ihl = skb->nh.iph->ihl*4; | |
202 | ||
1da177e4 LT |
203 | __skb_pull(skb, ihl); |
204 | ||
1da177e4 LT |
205 | /* 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 | */ | |
d13964f4 PM |
223 | if (raw_sk && !raw_v4_input(skb, skb->nh.iph, hash)) |
224 | raw_sk = NULL; | |
1da177e4 LT |
225 | |
226 | if ((ipprot = rcu_dereference(inet_protos[hash])) != NULL) { | |
227 | int ret; | |
228 | ||
b59c2701 PM |
229 | 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); | |
1da177e4 LT |
235 | } |
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 | */ | |
263 | int 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 | ||
d245407e TG |
279 | static 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; | |
327 | drop: | |
328 | return -1; | |
329 | } | |
330 | ||
1da177e4 LT |
331 | static inline int ip_rcv_finish(struct sk_buff *skb) |
332 | { | |
1da177e4 LT |
333 | 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 | */ | |
0182bd2b | 339 | if (skb->dst == NULL) { |
3e192bea TG |
340 | int err = ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, |
341 | skb->dev); | |
342 | if (unlikely(err)) { | |
2c2910a4 DE |
343 | if (err == -EHOSTUNREACH) |
344 | IP_INC_STATS_BH(IPSTATS_MIB_INADDRERRORS); | |
1da177e4 | 345 | goto drop; |
2c2910a4 | 346 | } |
1da177e4 LT |
347 | } |
348 | ||
349 | #ifdef CONFIG_NET_CLS_ROUTE | |
3e192bea | 350 | if (unlikely(skb->dst->tclassid)) { |
1da177e4 LT |
351 | 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 | ||
d245407e TG |
360 | if (iph->ihl > 5 && ip_rcv_options(skb)) |
361 | goto drop; | |
1da177e4 LT |
362 | |
363 | return dst_input(skb); | |
364 | ||
1da177e4 LT |
365 | drop: |
366 | kfree_skb(skb); | |
367 | return NET_RX_DROP; | |
368 | } | |
369 | ||
370 | /* | |
371 | * Main IP Receive routine. | |
372 | */ | |
f2ccd8fa | 373 | int ip_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev) |
1da177e4 LT |
374 | { |
375 | struct iphdr *iph; | |
58615242 | 376 | u32 len; |
1da177e4 LT |
377 | |
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) | |
58615242 | 408 | goto inhdr_error; |
1da177e4 LT |
409 | |
410 | if (!pskb_may_pull(skb, iph->ihl*4)) | |
411 | goto inhdr_error; | |
412 | ||
413 | iph = skb->nh.iph; | |
414 | ||
e9c60422 | 415 | if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl))) |
58615242 | 416 | goto inhdr_error; |
1da177e4 | 417 | |
58615242 TG |
418 | len = ntohs(iph->tot_len); |
419 | if (skb->len < len || len < (iph->ihl*4)) | |
420 | goto inhdr_error; | |
1da177e4 | 421 | |
58615242 TG |
422 | /* 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; | |
1da177e4 LT |
429 | } |
430 | ||
53602f92 | 431 | /* Remove any debris in the socket control block */ |
d569f1d7 | 432 | memset(IPCB(skb), 0, sizeof(struct inet_skb_parm)); |
53602f92 | 433 | |
1da177e4 LT |
434 | return NF_HOOK(PF_INET, NF_IP_PRE_ROUTING, skb, dev, NULL, |
435 | ip_rcv_finish); | |
436 | ||
437 | inhdr_error: | |
438 | IP_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS); | |
439 | drop: | |
440 | kfree_skb(skb); | |
441 | out: | |
442 | return NET_RX_DROP; | |
443 | } | |
444 | ||
1da177e4 | 445 | EXPORT_SYMBOL(ip_statistics); |