blob: 3d4da2c16b6a3c6d6bc41d8fec0ed182037b0801 [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 *
Jesper Juhl02c30a82005-05-05 16:16:16 -07008 * Authors: Ross Biro
Linus Torvalds1da177e2005-04-16 15:20:36 -07009 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
10 * Donald Becker, <becker@super.org>
Alan Cox113aa832008-10-13 19:01:08 -070011 * Alan Cox, <alan@lxorguk.ukuu.org.uk>
Linus Torvalds1da177e2005-04-16 15:20:36 -070012 * Richard Underwood
13 * Stefan Becker, <stefanb@yello.ping.de>
14 * Jorge Cwik, <jorge@laser.satlink.net>
15 * Arnt Gulbrandsen, <agulbra@nvg.unit.no>
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +090016 *
Linus Torvalds1da177e2005-04-16 15:20:36 -070017 *
18 * Fixes:
19 * Alan Cox : Commented a couple of minor bits of surplus code
20 * Alan Cox : Undefining IP_FORWARD doesn't include the code
21 * (just stops a compiler warning).
22 * Alan Cox : Frames with >=MAX_ROUTE record routes, strict routes or loose routes
23 * are junked rather than corrupting things.
24 * Alan Cox : Frames to bad broadcast subnets are dumped
25 * We used to process them non broadcast and
26 * boy could that cause havoc.
27 * Alan Cox : ip_forward sets the free flag on the
28 * new frame it queues. Still crap because
29 * it copies the frame but at least it
30 * doesn't eat memory too.
31 * Alan Cox : Generic queue code and memory fixes.
32 * Fred Van Kempen : IP fragment support (borrowed from NET2E)
33 * Gerhard Koerting: Forward fragmented frames correctly.
34 * Gerhard Koerting: Fixes to my fix of the above 8-).
35 * Gerhard Koerting: IP interface addressing fix.
36 * Linus Torvalds : More robustness checks
37 * Alan Cox : Even more checks: Still not as robust as it ought to be
38 * Alan Cox : Save IP header pointer for later
39 * Alan Cox : ip option setting
40 * Alan Cox : Use ip_tos/ip_ttl settings
41 * Alan Cox : Fragmentation bogosity removed
42 * (Thanks to Mark.Bush@prg.ox.ac.uk)
43 * Dmitry Gorodchanin : Send of a raw packet crash fix.
44 * Alan Cox : Silly ip bug when an overlength
45 * fragment turns up. Now frees the
46 * queue.
47 * Linus Torvalds/ : Memory leakage on fragmentation
48 * Alan Cox : handling.
49 * Gerhard Koerting: Forwarding uses IP priority hints
50 * Teemu Rantanen : Fragment problems.
51 * Alan Cox : General cleanup, comments and reformat
52 * Alan Cox : SNMP statistics
53 * Alan Cox : BSD address rule semantics. Also see
54 * UDP as there is a nasty checksum issue
55 * if you do things the wrong way.
56 * Alan Cox : Always defrag, moved IP_FORWARD to the config.in file
57 * Alan Cox : IP options adjust sk->priority.
58 * Pedro Roque : Fix mtu/length error in ip_forward.
59 * Alan Cox : Avoid ip_chk_addr when possible.
60 * Richard Underwood : IP multicasting.
61 * Alan Cox : Cleaned up multicast handlers.
62 * Alan Cox : RAW sockets demultiplex in the BSD style.
63 * Gunther Mayer : Fix the SNMP reporting typo
64 * Alan Cox : Always in group 224.0.0.1
65 * Pauline Middelink : Fast ip_checksum update when forwarding
66 * Masquerading support.
67 * Alan Cox : Multicast loopback error for 224.0.0.1
68 * Alan Cox : IP_MULTICAST_LOOP option.
69 * Alan Cox : Use notifiers.
70 * Bjorn Ekwall : Removed ip_csum (from slhc.c too)
71 * Bjorn Ekwall : Moved ip_fast_csum to ip.h (inline!)
72 * Stefan Becker : Send out ICMP HOST REDIRECT
73 * Arnt Gulbrandsen : ip_build_xmit
74 * Alan Cox : Per socket routing cache
75 * Alan Cox : Fixed routing cache, added header cache.
76 * Alan Cox : Loopback didn't work right in original ip_build_xmit - fixed it.
77 * Alan Cox : Only send ICMP_REDIRECT if src/dest are the same net.
78 * Alan Cox : Incoming IP option handling.
79 * Alan Cox : Set saddr on raw output frames as per BSD.
80 * Alan Cox : Stopped broadcast source route explosions.
81 * Alan Cox : Can disable source routing
82 * Takeshi Sone : Masquerading didn't work.
83 * Dave Bonn,Alan Cox : Faster IP forwarding whenever possible.
84 * Alan Cox : Memory leaks, tramples, misc debugging.
85 * Alan Cox : Fixed multicast (by popular demand 8))
86 * Alan Cox : Fixed forwarding (by even more popular demand 8))
87 * Alan Cox : Fixed SNMP statistics [I think]
88 * Gerhard Koerting : IP fragmentation forwarding fix
89 * Alan Cox : Device lock against page fault.
90 * Alan Cox : IP_HDRINCL facility.
91 * Werner Almesberger : Zero fragment bug
92 * Alan Cox : RAW IP frame length bug
93 * Alan Cox : Outgoing firewall on build_xmit
94 * A.N.Kuznetsov : IP_OPTIONS support throughout the kernel
95 * Alan Cox : Multicast routing hooks
96 * Jos Vos : Do accounting *before* call_in_firewall
97 * Willy Konynenberg : Transparent proxying support
98 *
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +090099 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700100 *
101 * To Fix:
102 * IP fragmentation wants rewriting cleanly. The RFC815 algorithm is much more efficient
103 * and could be made very efficient with the addition of some virtual memory hacks to permit
104 * the allocation of a buffer that can then be 'grown' by twiddling page tables.
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900105 * Output fragmentation wants updating along with the buffer management to use a single
Linus Torvalds1da177e2005-04-16 15:20:36 -0700106 * interleaved copy algorithm so that fragmenting has a one copy overhead. Actual packet
107 * output should probably do its own fragmentation at the UDP/RAW layer. TCP shouldn't cause
108 * fragmentation anyway.
109 *
110 * This program is free software; you can redistribute it and/or
111 * modify it under the terms of the GNU General Public License
112 * as published by the Free Software Foundation; either version
113 * 2 of the License, or (at your option) any later version.
114 */
115
Joe Perchesafd465032012-03-12 07:03:32 +0000116#define pr_fmt(fmt) "IPv4: " fmt
117
Linus Torvalds1da177e2005-04-16 15:20:36 -0700118#include <linux/module.h>
119#include <linux/types.h>
120#include <linux/kernel.h>
121#include <linux/string.h>
122#include <linux/errno.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +0900123#include <linux/slab.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>
Eric Dumazet1f07d032013-08-06 03:32:11 -0700144#include <net/inet_ecn.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700145#include <linux/netfilter_ipv4.h>
146#include <net/xfrm.h>
147#include <linux/mroute.h>
148#include <linux/netlink.h>
149
150/*
Eric Dumazet66018502010-06-07 03:12:08 +0000151 * Process Router Attention IP option (RFC 2113)
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900152 */
David S. Millerba57b4d2012-03-07 20:45:32 -0500153bool ip_call_ra_chain(struct sk_buff *skb)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700154{
155 struct ip_ra_chain *ra;
Arnaldo Carvalho de Meloeddc9ec2007-04-20 22:47:35 -0700156 u8 protocol = ip_hdr(skb)->protocol;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700157 struct sock *last = NULL;
Denis V. Lunevcb846632008-03-24 15:31:00 -0700158 struct net_device *dev = skb->dev;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700159
Eric Dumazet66018502010-06-07 03:12:08 +0000160 for (ra = rcu_dereference(ip_ra_chain); ra; ra = rcu_dereference(ra->next)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161 struct sock *sk = ra->sk;
162
163 /* If socket is bound to an interface, only report
164 * the packet if it came from that interface.
165 */
Eric Dumazetc720c7e2009-10-15 06:30:45 +0000166 if (sk && inet_sk(sk)->inet_num == protocol &&
Linus Torvalds1da177e2005-04-16 15:20:36 -0700167 (!sk->sk_bound_dev_if ||
Denis V. Lunevcb846632008-03-24 15:31:00 -0700168 sk->sk_bound_dev_if == dev->ifindex) &&
Octavian Purdila09ad9bc2009-11-25 15:14:13 -0800169 net_eq(sock_net(sk), dev_net(dev))) {
Paul Gortmaker56f8a752011-06-21 20:33:34 -0700170 if (ip_is_fragment(ip_hdr(skb))) {
Eric Dumazet66018502010-06-07 03:12:08 +0000171 if (ip_defrag(skb, IP_DEFRAG_CALL_RA_CHAIN))
David S. Millerba57b4d2012-03-07 20:45:32 -0500172 return true;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700173 }
174 if (last) {
175 struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
176 if (skb2)
177 raw_rcv(last, skb2);
178 }
179 last = sk;
180 }
181 }
182
183 if (last) {
184 raw_rcv(last, skb);
David S. Millerba57b4d2012-03-07 20:45:32 -0500185 return true;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700186 }
David S. Millerba57b4d2012-03-07 20:45:32 -0500187 return false;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700188}
189
Patrick McHardy861d0482007-10-15 01:48:39 -0700190static int ip_local_deliver_finish(struct sk_buff *skb)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700191{
YOSHIFUJI Hideakic346dca2008-03-25 21:47:49 +0900192 struct net *net = dev_net(skb->dev);
Denis V. Lunevf1450492008-03-24 15:33:00 -0700193
Eric Dumazet21d11962013-07-15 20:03:19 -0700194 __skb_pull(skb, skb_network_header_len(skb));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700195
196 rcu_read_lock();
197 {
Arnaldo Carvalho de Meloeddc9ec2007-04-20 22:47:35 -0700198 int protocol = ip_hdr(skb)->protocol;
Alexey Dobriyan32613092009-09-14 12:21:47 +0000199 const struct net_protocol *ipprot;
David S. Millerf9242b62012-06-19 18:56:21 -0700200 int raw;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201
202 resubmit:
Pavel Emelyanov7bc54c92007-11-19 22:35:07 -0800203 raw = raw_local_deliver(skb, protocol);
204
David S. Millerf9242b62012-06-19 18:56:21 -0700205 ipprot = rcu_dereference(inet_protos[protocol]);
Alexey Dobriyan9c0188a2008-11-12 23:23:51 -0800206 if (ipprot != NULL) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700207 int ret;
208
Patrick McHardyb59c2702006-01-06 23:06:10 -0800209 if (!ipprot->no_policy) {
210 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
211 kfree_skb(skb);
212 goto out;
213 }
214 nf_reset(skb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700215 }
216 ret = ipprot->handler(skb);
217 if (ret < 0) {
218 protocol = -ret;
219 goto resubmit;
220 }
Pavel Emelyanov7c73a6f2008-07-16 20:20:11 -0700221 IP_INC_STATS_BH(net, IPSTATS_MIB_INDELIVERS);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700222 } else {
Pavel Emelyanov7bc54c92007-11-19 22:35:07 -0800223 if (!raw) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700224 if (xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
Pavel Emelyanov7c73a6f2008-07-16 20:20:11 -0700225 IP_INC_STATS_BH(net, IPSTATS_MIB_INUNKNOWNPROTOS);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700226 icmp_send(skb, ICMP_DEST_UNREACH,
227 ICMP_PROT_UNREACH, 0);
228 }
Neil Hormand8c6f4b2013-03-01 07:44:08 +0000229 kfree_skb(skb);
230 } else {
Pavel Emelyanov7c73a6f2008-07-16 20:20:11 -0700231 IP_INC_STATS_BH(net, IPSTATS_MIB_INDELIVERS);
Neil Hormand8c6f4b2013-03-01 07:44:08 +0000232 consume_skb(skb);
233 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700234 }
235 }
236 out:
237 rcu_read_unlock();
238
239 return 0;
240}
241
242/*
243 * Deliver IP Packets to the higher protocol layers.
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900244 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700245int ip_local_deliver(struct sk_buff *skb)
246{
247 /*
248 * Reassemble IP fragments.
249 */
250
Paul Gortmaker56f8a752011-06-21 20:33:34 -0700251 if (ip_is_fragment(ip_hdr(skb))) {
Herbert Xu776c7292007-10-14 00:38:32 -0700252 if (ip_defrag(skb, IP_DEFRAG_LOCAL_DELIVER))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700253 return 0;
254 }
255
Jan Engelhardt9bbc7682010-03-23 04:07:29 +0100256 return NF_HOOK(NFPROTO_IPV4, NF_INET_LOCAL_IN, skb, skb->dev, NULL,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700257 ip_local_deliver_finish);
258}
259
David S. Miller6a913952012-03-07 20:48:08 -0500260static inline bool ip_rcv_options(struct sk_buff *skb)
Thomas Grafd2454072005-08-20 17:26:12 -0700261{
262 struct ip_options *opt;
Eric Dumazetb71d1d42011-04-22 04:53:02 +0000263 const struct iphdr *iph;
Thomas Grafd2454072005-08-20 17:26:12 -0700264 struct net_device *dev = skb->dev;
265
266 /* It looks as overkill, because not all
267 IP options require packet mangling.
268 But it is the easiest for now, especially taking
269 into account that combination of IP options
270 and running sniffer is extremely rare condition.
271 --ANK (980813)
272 */
273 if (skb_cow(skb, skb_headroom(skb))) {
Pavel Emelyanov7c73a6f2008-07-16 20:20:11 -0700274 IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
Thomas Grafd2454072005-08-20 17:26:12 -0700275 goto drop;
276 }
277
Arnaldo Carvalho de Meloeddc9ec2007-04-20 22:47:35 -0700278 iph = ip_hdr(skb);
Denis V. Lunev22aba382008-03-22 16:36:20 -0700279 opt = &(IPCB(skb)->opt);
280 opt->optlen = iph->ihl*4 - sizeof(struct iphdr);
Thomas Grafd2454072005-08-20 17:26:12 -0700281
YOSHIFUJI Hideakic346dca2008-03-25 21:47:49 +0900282 if (ip_options_compile(dev_net(dev), opt, skb)) {
Pavel Emelyanov7c73a6f2008-07-16 20:20:11 -0700283 IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INHDRERRORS);
Thomas Grafd2454072005-08-20 17:26:12 -0700284 goto drop;
285 }
286
Thomas Grafd2454072005-08-20 17:26:12 -0700287 if (unlikely(opt->srr)) {
Eric Dumazet6e8b11b2010-06-07 03:54:46 +0000288 struct in_device *in_dev = __in_dev_get_rcu(dev);
289
Thomas Grafd2454072005-08-20 17:26:12 -0700290 if (in_dev) {
291 if (!IN_DEV_SOURCE_ROUTE(in_dev)) {
Joe Perchese87cc472012-05-13 21:56:26 +0000292 if (IN_DEV_LOG_MARTIANS(in_dev))
293 net_info_ratelimited("source route option %pI4 -> %pI4\n",
294 &iph->saddr,
295 &iph->daddr);
Thomas Grafd2454072005-08-20 17:26:12 -0700296 goto drop;
297 }
Thomas Grafd2454072005-08-20 17:26:12 -0700298 }
299
300 if (ip_options_rcv_srr(skb))
301 goto drop;
302 }
303
David S. Miller6a913952012-03-07 20:48:08 -0500304 return false;
Thomas Grafd2454072005-08-20 17:26:12 -0700305drop:
David S. Miller6a913952012-03-07 20:48:08 -0500306 return true;
Thomas Grafd2454072005-08-20 17:26:12 -0700307}
308
Alexander Duyck6648bd72012-06-21 13:58:31 +0000309int sysctl_ip_early_demux __read_mostly = 1;
Eric Dumazetc7109982012-07-26 12:18:11 +0000310EXPORT_SYMBOL(sysctl_ip_early_demux);
Alexander Duyck6648bd72012-06-21 13:58:31 +0000311
Patrick McHardy861d0482007-10-15 01:48:39 -0700312static int ip_rcv_finish(struct sk_buff *skb)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700313{
Arnaldo Carvalho de Meloeddc9ec2007-04-20 22:47:35 -0700314 const struct iphdr *iph = ip_hdr(skb);
Mitsuru Chinen5506b542007-04-30 00:48:10 -0700315 struct rtable *rt;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700316
Holger Eitzenbergera452ce32014-01-27 10:33:18 +0100317 if (sysctl_ip_early_demux && !skb_dst(skb) && skb->sk == NULL) {
David S. Miller160eb5a2012-06-27 22:01:22 -0700318 const struct net_protocol *ipprot;
319 int protocol = iph->protocol;
320
David S. Miller160eb5a2012-06-27 22:01:22 -0700321 ipprot = rcu_dereference(inet_protos[protocol]);
Eric Dumazet9cb429d2012-07-24 01:19:31 +0000322 if (ipprot && ipprot->early_demux) {
David S. Miller160eb5a2012-06-27 22:01:22 -0700323 ipprot->early_demux(skb);
Eric Dumazet9cb429d2012-07-24 01:19:31 +0000324 /* must reload iph, skb->head might have changed */
325 iph = ip_hdr(skb);
326 }
David S. Miller160eb5a2012-06-27 22:01:22 -0700327 }
328
Linus Torvalds1da177e2005-04-16 15:20:36 -0700329 /*
330 * Initialise the virtual path cache for the packet. It describes
331 * how the packet travels inside Linux networking.
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900332 */
David S. Miller160eb5a2012-06-27 22:01:22 -0700333 if (!skb_dst(skb)) {
David S. Millerc6cffba2012-07-26 11:14:38 +0000334 int err = ip_route_input_noref(skb, iph->daddr, iph->saddr,
335 iph->tos, skb->dev);
David S. Miller160eb5a2012-06-27 22:01:22 -0700336 if (unlikely(err)) {
337 if (err == -EXDEV)
338 NET_INC_STATS_BH(dev_net(skb->dev),
339 LINUX_MIB_IPRPFILTER);
340 goto drop;
Dietmar Eggemann2c2910a2005-06-28 13:06:23 -0700341 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700342 }
343
Patrick McHardyc7066f72011-01-14 13:36:42 +0100344#ifdef CONFIG_IP_ROUTE_CLASSID
Eric Dumazetadf30902009-06-02 05:19:30 +0000345 if (unlikely(skb_dst(skb)->tclassid)) {
Eric Dumazet7a9b2d52010-06-24 00:52:37 +0000346 struct ip_rt_acct *st = this_cpu_ptr(ip_rt_acct);
Eric Dumazetadf30902009-06-02 05:19:30 +0000347 u32 idx = skb_dst(skb)->tclassid;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700348 st[idx&0xFF].o_packets++;
Jianjun Kongfd3f8c42008-11-03 02:47:38 -0800349 st[idx&0xFF].o_bytes += skb->len;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700350 st[(idx>>16)&0xFF].i_packets++;
Jianjun Kongfd3f8c42008-11-03 02:47:38 -0800351 st[(idx>>16)&0xFF].i_bytes += skb->len;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700352 }
353#endif
354
Thomas Grafd2454072005-08-20 17:26:12 -0700355 if (iph->ihl > 5 && ip_rcv_options(skb))
356 goto drop;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700357
Eric Dumazet511c3f92009-06-02 05:14:27 +0000358 rt = skb_rtable(skb);
Neil Hormanedf391f2009-04-27 02:45:02 -0700359 if (rt->rt_type == RTN_MULTICAST) {
Changli Gaod8d1f302010-06-10 23:31:35 -0700360 IP_UPD_PO_STATS_BH(dev_net(rt->dst.dev), IPSTATS_MIB_INMCAST,
Neil Hormanedf391f2009-04-27 02:45:02 -0700361 skb->len);
362 } else if (rt->rt_type == RTN_BROADCAST)
Changli Gaod8d1f302010-06-10 23:31:35 -0700363 IP_UPD_PO_STATS_BH(dev_net(rt->dst.dev), IPSTATS_MIB_INBCAST,
Neil Hormanedf391f2009-04-27 02:45:02 -0700364 skb->len);
Mitsuru Chinen5506b542007-04-30 00:48:10 -0700365
Linus Torvalds1da177e2005-04-16 15:20:36 -0700366 return dst_input(skb);
367
Linus Torvalds1da177e2005-04-16 15:20:36 -0700368drop:
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900369 kfree_skb(skb);
370 return NET_RX_DROP;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700371}
372
373/*
374 * Main IP Receive routine.
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900375 */
David S. Millerf2ccd8f2005-08-09 19:34:12 -0700376int 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 -0700377{
Eric Dumazetb71d1d42011-04-22 04:53:02 +0000378 const struct iphdr *iph;
Thomas Graf58615242005-08-20 17:25:29 -0700379 u32 len;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700380
381 /* When the interface is in promisc. mode, drop all the crap
382 * that it receives, do not try to analyse it.
383 */
384 if (skb->pkt_type == PACKET_OTHERHOST)
385 goto drop;
386
Neil Hormanedf391f2009-04-27 02:45:02 -0700387
388 IP_UPD_PO_STATS_BH(dev_net(dev), IPSTATS_MIB_IN, skb->len);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700389
390 if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL) {
Pavel Emelyanov7c73a6f2008-07-16 20:20:11 -0700391 IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700392 goto out;
393 }
394
395 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
396 goto inhdr_error;
397
Arnaldo Carvalho de Meloeddc9ec2007-04-20 22:47:35 -0700398 iph = ip_hdr(skb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700399
400 /*
J.H.M. Dassen (Ray)c67fa022008-05-08 01:11:04 -0700401 * RFC1122: 3.2.1.2 MUST silently discard any IP frame that fails the checksum.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700402 *
403 * Is the datagram acceptable?
404 *
405 * 1. Length at least the size of an ip header
406 * 2. Version of 4
407 * 3. Checksums correctly. [Speed optimisation for later, skip loopback checksums]
408 * 4. Doesn't have a bogus length
409 */
410
411 if (iph->ihl < 5 || iph->version != 4)
Thomas Graf58615242005-08-20 17:25:29 -0700412 goto inhdr_error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700413
Eric Dumazet1f07d032013-08-06 03:32:11 -0700414 BUILD_BUG_ON(IPSTATS_MIB_ECT1PKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_ECT_1);
415 BUILD_BUG_ON(IPSTATS_MIB_ECT0PKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_ECT_0);
416 BUILD_BUG_ON(IPSTATS_MIB_CEPKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_CE);
417 IP_ADD_STATS_BH(dev_net(dev),
418 IPSTATS_MIB_NOECTPKTS + (iph->tos & INET_ECN_MASK),
419 max_t(unsigned short, 1, skb_shinfo(skb)->gso_segs));
420
Linus Torvalds1da177e2005-04-16 15:20:36 -0700421 if (!pskb_may_pull(skb, iph->ihl*4))
422 goto inhdr_error;
423
Arnaldo Carvalho de Meloeddc9ec2007-04-20 22:47:35 -0700424 iph = ip_hdr(skb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700425
Thomas Grafe9c60422005-08-20 17:25:52 -0700426 if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
Eric Dumazet6a5dc9e2013-04-29 08:39:56 +0000427 goto csum_error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700428
Thomas Graf58615242005-08-20 17:25:29 -0700429 len = ntohs(iph->tot_len);
Mitsuru Chinen704aed52007-04-30 00:46:30 -0700430 if (skb->len < len) {
Pavel Emelyanov7c73a6f2008-07-16 20:20:11 -0700431 IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INTRUNCATEDPKTS);
Mitsuru Chinen704aed52007-04-30 00:46:30 -0700432 goto drop;
433 } else if (len < (iph->ihl*4))
Thomas Graf58615242005-08-20 17:25:29 -0700434 goto inhdr_error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700435
Thomas Graf58615242005-08-20 17:25:29 -0700436 /* Our transport medium may have padded the buffer out. Now we know it
437 * is IP we can trim to the true length of the frame.
438 * Note this now means skb->len holds ntohs(iph->tot_len).
439 */
440 if (pskb_trim_rcsum(skb, len)) {
Pavel Emelyanov7c73a6f2008-07-16 20:20:11 -0700441 IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
Thomas Graf58615242005-08-20 17:25:29 -0700442 goto drop;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700443 }
444
Eric Dumazet21d11962013-07-15 20:03:19 -0700445 skb->transport_header = skb->network_header + iph->ihl*4;
446
Stephen Hemminger53602f92006-07-14 14:49:32 -0700447 /* Remove any debris in the socket control block */
Guillaume Chazaraind569f1d2006-07-24 23:45:16 -0700448 memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
Stephen Hemminger53602f92006-07-14 14:49:32 -0700449
Herbert Xu71f9dac2009-06-26 19:22:37 -0700450 /* Must drop socket now because of tproxy. */
451 skb_orphan(skb);
452
Jan Engelhardt9bbc7682010-03-23 04:07:29 +0100453 return NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, skb, dev, NULL,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700454 ip_rcv_finish);
455
Eric Dumazet6a5dc9e2013-04-29 08:39:56 +0000456csum_error:
457 IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_CSUMERRORS);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700458inhdr_error:
Pavel Emelyanov7c73a6f2008-07-16 20:20:11 -0700459 IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INHDRERRORS);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700460drop:
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900461 kfree_skb(skb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700462out:
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900463 return NET_RX_DROP;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700464}