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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 * Authors: Ross Biro
9 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
10 * Donald Becker, <becker@super.org>
11 * Alan Cox, <alan@lxorguk.ukuu.org.uk>
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 *
17 *
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 *
99 *
100 *
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.
105 * Output fragmentation wants updating along with the buffer management to use a single
106 * 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
116#define pr_fmt(fmt) "IPv4: " fmt
117
118#include <linux/module.h>
119#include <linux/types.h>
120#include <linux/kernel.h>
121#include <linux/string.h>
122#include <linux/errno.h>
123#include <linux/slab.h>
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>
130#include <linux/inetdevice.h>
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 <net/inet_ecn.h>
145#include <linux/netfilter_ipv4.h>
146#include <net/xfrm.h>
147#include <linux/mroute.h>
148#include <linux/netlink.h>
149
150/*
151 * Process Router Attention IP option (RFC 2113)
152 */
153bool ip_call_ra_chain(struct sk_buff *skb)
154{
155 struct ip_ra_chain *ra;
156 u8 protocol = ip_hdr(skb)->protocol;
157 struct sock *last = NULL;
158 struct net_device *dev = skb->dev;
159
160 for (ra = rcu_dereference(ip_ra_chain); ra; ra = rcu_dereference(ra->next)) {
161 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 */
166 if (sk && inet_sk(sk)->inet_num == protocol &&
167 (!sk->sk_bound_dev_if ||
168 sk->sk_bound_dev_if == dev->ifindex) &&
169 net_eq(sock_net(sk), dev_net(dev))) {
170 if (ip_is_fragment(ip_hdr(skb))) {
171 if (ip_defrag(skb, IP_DEFRAG_CALL_RA_CHAIN))
172 return true;
173 }
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);
185 return true;
186 }
187 return false;
188}
189
190static int ip_local_deliver_finish(struct sk_buff *skb)
191{
192 struct net *net = dev_net(skb->dev);
193
194 __skb_pull(skb, skb_network_header_len(skb));
195
196 rcu_read_lock();
197 {
198 int protocol = ip_hdr(skb)->protocol;
199 const struct net_protocol *ipprot;
200 int raw;
201
202 resubmit:
203 raw = raw_local_deliver(skb, protocol);
204
205 ipprot = rcu_dereference(inet_protos[protocol]);
206 if (ipprot != NULL) {
207 int ret;
208
209 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);
215 }
216 ret = ipprot->handler(skb);
217 if (ret < 0) {
218 protocol = -ret;
219 goto resubmit;
220 }
221 IP_INC_STATS_BH(net, IPSTATS_MIB_INDELIVERS);
222 } else {
223 if (!raw) {
224 if (xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
225 IP_INC_STATS_BH(net, IPSTATS_MIB_INUNKNOWNPROTOS);
226 icmp_send(skb, ICMP_DEST_UNREACH,
227 ICMP_PROT_UNREACH, 0);
228 }
229 kfree_skb(skb);
230 } else {
231 IP_INC_STATS_BH(net, IPSTATS_MIB_INDELIVERS);
232 consume_skb(skb);
233 }
234 }
235 }
236 out:
237 rcu_read_unlock();
238
239 return 0;
240}
241
242/*
243 * Deliver IP Packets to the higher protocol layers.
244 */
245int ip_local_deliver(struct sk_buff *skb)
246{
247 /*
248 * Reassemble IP fragments.
249 */
250
251 if (ip_is_fragment(ip_hdr(skb))) {
252 if (ip_defrag(skb, IP_DEFRAG_LOCAL_DELIVER))
253 return 0;
254 }
255
256 return NF_HOOK(NFPROTO_IPV4, NF_INET_LOCAL_IN, skb, skb->dev, NULL,
257 ip_local_deliver_finish);
258}
259
260static inline bool ip_rcv_options(struct sk_buff *skb)
261{
262 struct ip_options *opt;
263 const struct iphdr *iph;
264 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))) {
274 IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
275 goto drop;
276 }
277
278 iph = ip_hdr(skb);
279 opt = &(IPCB(skb)->opt);
280 opt->optlen = iph->ihl*4 - sizeof(struct iphdr);
281
282 if (ip_options_compile(dev_net(dev), opt, skb)) {
283 IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INHDRERRORS);
284 goto drop;
285 }
286
287 if (unlikely(opt->srr)) {
288 struct in_device *in_dev = __in_dev_get_rcu(dev);
289
290 if (in_dev) {
291 if (!IN_DEV_SOURCE_ROUTE(in_dev)) {
292 if (IN_DEV_LOG_MARTIANS(in_dev))
293 net_info_ratelimited("source route option %pI4 -> %pI4\n",
294 &iph->saddr,
295 &iph->daddr);
296 goto drop;
297 }
298 }
299
300 if (ip_options_rcv_srr(skb))
301 goto drop;
302 }
303
304 return false;
305drop:
306 return true;
307}
308
309int sysctl_ip_early_demux __read_mostly = 1;
310EXPORT_SYMBOL(sysctl_ip_early_demux);
311
312static int ip_rcv_finish(struct sk_buff *skb)
313{
314 const struct iphdr *iph = ip_hdr(skb);
315 struct rtable *rt;
316
317 if (sysctl_ip_early_demux && !skb_dst(skb) && skb->sk == NULL) {
318 const struct net_protocol *ipprot;
319 int protocol = iph->protocol;
320
321 ipprot = rcu_dereference(inet_protos[protocol]);
322 if (ipprot && ipprot->early_demux) {
323 ipprot->early_demux(skb);
324 /* must reload iph, skb->head might have changed */
325 iph = ip_hdr(skb);
326 }
327 }
328
329 /*
330 * Initialise the virtual path cache for the packet. It describes
331 * how the packet travels inside Linux networking.
332 */
333 if (!skb_dst(skb)) {
334 int err = ip_route_input_noref(skb, iph->daddr, iph->saddr,
335 iph->tos, skb->dev);
336 if (unlikely(err)) {
337 if (err == -EXDEV)
338 NET_INC_STATS_BH(dev_net(skb->dev),
339 LINUX_MIB_IPRPFILTER);
340 goto drop;
341 }
342 }
343
344#ifdef CONFIG_IP_ROUTE_CLASSID
345 if (unlikely(skb_dst(skb)->tclassid)) {
346 struct ip_rt_acct *st = this_cpu_ptr(ip_rt_acct);
347 u32 idx = skb_dst(skb)->tclassid;
348 st[idx&0xFF].o_packets++;
349 st[idx&0xFF].o_bytes += skb->len;
350 st[(idx>>16)&0xFF].i_packets++;
351 st[(idx>>16)&0xFF].i_bytes += skb->len;
352 }
353#endif
354
355 if (iph->ihl > 5 && ip_rcv_options(skb))
356 goto drop;
357
358 rt = skb_rtable(skb);
359 if (rt->rt_type == RTN_MULTICAST) {
360 IP_UPD_PO_STATS_BH(dev_net(rt->dst.dev), IPSTATS_MIB_INMCAST,
361 skb->len);
362 } else if (rt->rt_type == RTN_BROADCAST)
363 IP_UPD_PO_STATS_BH(dev_net(rt->dst.dev), IPSTATS_MIB_INBCAST,
364 skb->len);
365
366 return dst_input(skb);
367
368drop:
369 kfree_skb(skb);
370 return NET_RX_DROP;
371}
372
373/*
374 * Main IP Receive routine.
375 */
376int ip_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev)
377{
378 const struct iphdr *iph;
379 u32 len;
380
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
387
388 IP_UPD_PO_STATS_BH(dev_net(dev), IPSTATS_MIB_IN, skb->len);
389
390 if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL) {
391 IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
392 goto out;
393 }
394
395 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
396 goto inhdr_error;
397
398 iph = ip_hdr(skb);
399
400 /*
401 * RFC1122: 3.2.1.2 MUST silently discard any IP frame that fails the checksum.
402 *
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)
412 goto inhdr_error;
413
414 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
421 if (!pskb_may_pull(skb, iph->ihl*4))
422 goto inhdr_error;
423
424 iph = ip_hdr(skb);
425
426 if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
427 goto csum_error;
428
429 len = ntohs(iph->tot_len);
430 if (skb->len < len) {
431 IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INTRUNCATEDPKTS);
432 goto drop;
433 } else if (len < (iph->ihl*4))
434 goto inhdr_error;
435
436 /* 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)) {
441 IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
442 goto drop;
443 }
444
445 skb->transport_header = skb->network_header + iph->ihl*4;
446
447 /* Remove any debris in the socket control block */
448 memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
449
450 /* Must drop socket now because of tproxy. */
451 skb_orphan(skb);
452
453 return NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, skb, dev, NULL,
454 ip_rcv_finish);
455
456csum_error:
457 IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_CSUMERRORS);
458inhdr_error:
459 IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INHDRERRORS);
460drop:
461 kfree_skb(skb);
462out:
463 return NET_RX_DROP;
464}
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 * Authors: Ross Biro
9 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
10 * Donald Becker, <becker@super.org>
11 * Alan Cox, <alan@lxorguk.ukuu.org.uk>
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 *
17 *
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 *
99 *
100 *
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.
105 * Output fragmentation wants updating along with the buffer management to use a single
106 * 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
116#define pr_fmt(fmt) "IPv4: " fmt
117
118#include <linux/module.h>
119#include <linux/types.h>
120#include <linux/kernel.h>
121#include <linux/string.h>
122#include <linux/errno.h>
123#include <linux/slab.h>
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>
130#include <linux/inetdevice.h>
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 <net/inet_ecn.h>
145#include <linux/netfilter_ipv4.h>
146#include <net/xfrm.h>
147#include <linux/mroute.h>
148#include <linux/netlink.h>
149#include <net/dst_metadata.h>
150
151/*
152 * Process Router Attention IP option (RFC 2113)
153 */
154bool ip_call_ra_chain(struct sk_buff *skb)
155{
156 struct ip_ra_chain *ra;
157 u8 protocol = ip_hdr(skb)->protocol;
158 struct sock *last = NULL;
159 struct net_device *dev = skb->dev;
160 struct net *net = dev_net(dev);
161
162 for (ra = rcu_dereference(ip_ra_chain); ra; ra = rcu_dereference(ra->next)) {
163 struct sock *sk = ra->sk;
164
165 /* If socket is bound to an interface, only report
166 * the packet if it came from that interface.
167 */
168 if (sk && inet_sk(sk)->inet_num == protocol &&
169 (!sk->sk_bound_dev_if ||
170 sk->sk_bound_dev_if == dev->ifindex) &&
171 net_eq(sock_net(sk), net)) {
172 if (ip_is_fragment(ip_hdr(skb))) {
173 if (ip_defrag(net, skb, IP_DEFRAG_CALL_RA_CHAIN))
174 return true;
175 }
176 if (last) {
177 struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
178 if (skb2)
179 raw_rcv(last, skb2);
180 }
181 last = sk;
182 }
183 }
184
185 if (last) {
186 raw_rcv(last, skb);
187 return true;
188 }
189 return false;
190}
191
192static int ip_local_deliver_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
193{
194 __skb_pull(skb, skb_network_header_len(skb));
195
196 rcu_read_lock();
197 {
198 int protocol = ip_hdr(skb)->protocol;
199 const struct net_protocol *ipprot;
200 int raw;
201
202 resubmit:
203 raw = raw_local_deliver(skb, protocol);
204
205 ipprot = rcu_dereference(inet_protos[protocol]);
206 if (ipprot) {
207 int ret;
208
209 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);
215 }
216 ret = ipprot->handler(skb);
217 if (ret < 0) {
218 protocol = -ret;
219 goto resubmit;
220 }
221 __IP_INC_STATS(net, IPSTATS_MIB_INDELIVERS);
222 } else {
223 if (!raw) {
224 if (xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
225 __IP_INC_STATS(net, IPSTATS_MIB_INUNKNOWNPROTOS);
226 icmp_send(skb, ICMP_DEST_UNREACH,
227 ICMP_PROT_UNREACH, 0);
228 }
229 kfree_skb(skb);
230 } else {
231 __IP_INC_STATS(net, IPSTATS_MIB_INDELIVERS);
232 consume_skb(skb);
233 }
234 }
235 }
236 out:
237 rcu_read_unlock();
238
239 return 0;
240}
241
242/*
243 * Deliver IP Packets to the higher protocol layers.
244 */
245int ip_local_deliver(struct sk_buff *skb)
246{
247 /*
248 * Reassemble IP fragments.
249 */
250 struct net *net = dev_net(skb->dev);
251
252 if (ip_is_fragment(ip_hdr(skb))) {
253 if (ip_defrag(net, skb, IP_DEFRAG_LOCAL_DELIVER))
254 return 0;
255 }
256
257 return NF_HOOK(NFPROTO_IPV4, NF_INET_LOCAL_IN,
258 net, NULL, skb, skb->dev, NULL,
259 ip_local_deliver_finish);
260}
261
262static inline bool ip_rcv_options(struct sk_buff *skb)
263{
264 struct ip_options *opt;
265 const struct iphdr *iph;
266 struct net_device *dev = skb->dev;
267
268 /* It looks as overkill, because not all
269 IP options require packet mangling.
270 But it is the easiest for now, especially taking
271 into account that combination of IP options
272 and running sniffer is extremely rare condition.
273 --ANK (980813)
274 */
275 if (skb_cow(skb, skb_headroom(skb))) {
276 __IP_INC_STATS(dev_net(dev), IPSTATS_MIB_INDISCARDS);
277 goto drop;
278 }
279
280 iph = ip_hdr(skb);
281 opt = &(IPCB(skb)->opt);
282 opt->optlen = iph->ihl*4 - sizeof(struct iphdr);
283
284 if (ip_options_compile(dev_net(dev), opt, skb)) {
285 __IP_INC_STATS(dev_net(dev), IPSTATS_MIB_INHDRERRORS);
286 goto drop;
287 }
288
289 if (unlikely(opt->srr)) {
290 struct in_device *in_dev = __in_dev_get_rcu(dev);
291
292 if (in_dev) {
293 if (!IN_DEV_SOURCE_ROUTE(in_dev)) {
294 if (IN_DEV_LOG_MARTIANS(in_dev))
295 net_info_ratelimited("source route option %pI4 -> %pI4\n",
296 &iph->saddr,
297 &iph->daddr);
298 goto drop;
299 }
300 }
301
302 if (ip_options_rcv_srr(skb))
303 goto drop;
304 }
305
306 return false;
307drop:
308 return true;
309}
310
311static int ip_rcv_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
312{
313 const struct iphdr *iph = ip_hdr(skb);
314 struct rtable *rt;
315 struct net_device *dev = skb->dev;
316
317 /* if ingress device is enslaved to an L3 master device pass the
318 * skb to its handler for processing
319 */
320 skb = l3mdev_ip_rcv(skb);
321 if (!skb)
322 return NET_RX_SUCCESS;
323
324 if (net->ipv4.sysctl_ip_early_demux &&
325 !skb_dst(skb) &&
326 !skb->sk &&
327 !ip_is_fragment(iph)) {
328 const struct net_protocol *ipprot;
329 int protocol = iph->protocol;
330
331 ipprot = rcu_dereference(inet_protos[protocol]);
332 if (ipprot && ipprot->early_demux) {
333 ipprot->early_demux(skb);
334 /* must reload iph, skb->head might have changed */
335 iph = ip_hdr(skb);
336 }
337 }
338
339 /*
340 * Initialise the virtual path cache for the packet. It describes
341 * how the packet travels inside Linux networking.
342 */
343 if (!skb_valid_dst(skb)) {
344 int err = ip_route_input_noref(skb, iph->daddr, iph->saddr,
345 iph->tos, dev);
346 if (unlikely(err)) {
347 if (err == -EXDEV)
348 __NET_INC_STATS(net, LINUX_MIB_IPRPFILTER);
349 goto drop;
350 }
351 }
352
353#ifdef CONFIG_IP_ROUTE_CLASSID
354 if (unlikely(skb_dst(skb)->tclassid)) {
355 struct ip_rt_acct *st = this_cpu_ptr(ip_rt_acct);
356 u32 idx = skb_dst(skb)->tclassid;
357 st[idx&0xFF].o_packets++;
358 st[idx&0xFF].o_bytes += skb->len;
359 st[(idx>>16)&0xFF].i_packets++;
360 st[(idx>>16)&0xFF].i_bytes += skb->len;
361 }
362#endif
363
364 if (iph->ihl > 5 && ip_rcv_options(skb))
365 goto drop;
366
367 rt = skb_rtable(skb);
368 if (rt->rt_type == RTN_MULTICAST) {
369 __IP_UPD_PO_STATS(net, IPSTATS_MIB_INMCAST, skb->len);
370 } else if (rt->rt_type == RTN_BROADCAST) {
371 __IP_UPD_PO_STATS(net, IPSTATS_MIB_INBCAST, skb->len);
372 } else if (skb->pkt_type == PACKET_BROADCAST ||
373 skb->pkt_type == PACKET_MULTICAST) {
374 struct in_device *in_dev = __in_dev_get_rcu(dev);
375
376 /* RFC 1122 3.3.6:
377 *
378 * When a host sends a datagram to a link-layer broadcast
379 * address, the IP destination address MUST be a legal IP
380 * broadcast or IP multicast address.
381 *
382 * A host SHOULD silently discard a datagram that is received
383 * via a link-layer broadcast (see Section 2.4) but does not
384 * specify an IP multicast or broadcast destination address.
385 *
386 * This doesn't explicitly say L2 *broadcast*, but broadcast is
387 * in a way a form of multicast and the most common use case for
388 * this is 802.11 protecting against cross-station spoofing (the
389 * so-called "hole-196" attack) so do it for both.
390 */
391 if (in_dev &&
392 IN_DEV_ORCONF(in_dev, DROP_UNICAST_IN_L2_MULTICAST))
393 goto drop;
394 }
395
396 return dst_input(skb);
397
398drop:
399 kfree_skb(skb);
400 return NET_RX_DROP;
401}
402
403/*
404 * Main IP Receive routine.
405 */
406int ip_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev)
407{
408 const struct iphdr *iph;
409 struct net *net;
410 u32 len;
411
412 /* When the interface is in promisc. mode, drop all the crap
413 * that it receives, do not try to analyse it.
414 */
415 if (skb->pkt_type == PACKET_OTHERHOST)
416 goto drop;
417
418
419 net = dev_net(dev);
420 __IP_UPD_PO_STATS(net, IPSTATS_MIB_IN, skb->len);
421
422 skb = skb_share_check(skb, GFP_ATOMIC);
423 if (!skb) {
424 __IP_INC_STATS(net, IPSTATS_MIB_INDISCARDS);
425 goto out;
426 }
427
428 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
429 goto inhdr_error;
430
431 iph = ip_hdr(skb);
432
433 /*
434 * RFC1122: 3.2.1.2 MUST silently discard any IP frame that fails the checksum.
435 *
436 * Is the datagram acceptable?
437 *
438 * 1. Length at least the size of an ip header
439 * 2. Version of 4
440 * 3. Checksums correctly. [Speed optimisation for later, skip loopback checksums]
441 * 4. Doesn't have a bogus length
442 */
443
444 if (iph->ihl < 5 || iph->version != 4)
445 goto inhdr_error;
446
447 BUILD_BUG_ON(IPSTATS_MIB_ECT1PKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_ECT_1);
448 BUILD_BUG_ON(IPSTATS_MIB_ECT0PKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_ECT_0);
449 BUILD_BUG_ON(IPSTATS_MIB_CEPKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_CE);
450 __IP_ADD_STATS(net,
451 IPSTATS_MIB_NOECTPKTS + (iph->tos & INET_ECN_MASK),
452 max_t(unsigned short, 1, skb_shinfo(skb)->gso_segs));
453
454 if (!pskb_may_pull(skb, iph->ihl*4))
455 goto inhdr_error;
456
457 iph = ip_hdr(skb);
458
459 if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
460 goto csum_error;
461
462 len = ntohs(iph->tot_len);
463 if (skb->len < len) {
464 __IP_INC_STATS(net, IPSTATS_MIB_INTRUNCATEDPKTS);
465 goto drop;
466 } else if (len < (iph->ihl*4))
467 goto inhdr_error;
468
469 /* Our transport medium may have padded the buffer out. Now we know it
470 * is IP we can trim to the true length of the frame.
471 * Note this now means skb->len holds ntohs(iph->tot_len).
472 */
473 if (pskb_trim_rcsum(skb, len)) {
474 __IP_INC_STATS(net, IPSTATS_MIB_INDISCARDS);
475 goto drop;
476 }
477
478 skb->transport_header = skb->network_header + iph->ihl*4;
479
480 /* Remove any debris in the socket control block */
481 memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
482 IPCB(skb)->iif = skb->skb_iif;
483
484 /* Must drop socket now because of tproxy. */
485 skb_orphan(skb);
486
487 return NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING,
488 net, NULL, skb, dev, NULL,
489 ip_rcv_finish);
490
491csum_error:
492 __IP_INC_STATS(net, IPSTATS_MIB_CSUMERRORS);
493inhdr_error:
494 __IP_INC_STATS(net, IPSTATS_MIB_INHDRERRORS);
495drop:
496 kfree_skb(skb);
497out:
498 return NET_RX_DROP;
499}