1 | // SPDX-License-Identifier: GPL-2.0-or-later |
---|---|
2 | /* |
3 | * NET3: Implementation of the ICMP protocol layer. |
4 | * |
5 | * Alan Cox, <alan@lxorguk.ukuu.org.uk> |
6 | * |
7 | * Some of the function names and the icmp unreach table for this |
8 | * module were derived from [icmp.c 1.0.11 06/02/93] by |
9 | * Ross Biro, Fred N. van Kempen, Mark Evans, Alan Cox, Gerhard Koerting. |
10 | * Other than that this module is a complete rewrite. |
11 | * |
12 | * Fixes: |
13 | * Clemens Fruhwirth : introduce global icmp rate limiting |
14 | * with icmp type masking ability instead |
15 | * of broken per type icmp timeouts. |
16 | * Mike Shaver : RFC1122 checks. |
17 | * Alan Cox : Multicast ping reply as self. |
18 | * Alan Cox : Fix atomicity lockup in ip_build_xmit |
19 | * call. |
20 | * Alan Cox : Added 216,128 byte paths to the MTU |
21 | * code. |
22 | * Martin Mares : RFC1812 checks. |
23 | * Martin Mares : Can be configured to follow redirects |
24 | * if acting as a router _without_ a |
25 | * routing protocol (RFC 1812). |
26 | * Martin Mares : Echo requests may be configured to |
27 | * be ignored (RFC 1812). |
28 | * Martin Mares : Limitation of ICMP error message |
29 | * transmit rate (RFC 1812). |
30 | * Martin Mares : TOS and Precedence set correctly |
31 | * (RFC 1812). |
32 | * Martin Mares : Now copying as much data from the |
33 | * original packet as we can without |
34 | * exceeding 576 bytes (RFC 1812). |
35 | * Willy Konynenberg : Transparent proxying support. |
36 | * Keith Owens : RFC1191 correction for 4.2BSD based |
37 | * path MTU bug. |
38 | * Thomas Quinot : ICMP Dest Unreach codes up to 15 are |
39 | * valid (RFC 1812). |
40 | * Andi Kleen : Check all packet lengths properly |
41 | * and moved all kfree_skb() up to |
42 | * icmp_rcv. |
43 | * Andi Kleen : Move the rate limit bookkeeping |
44 | * into the dest entry and use a token |
45 | * bucket filter (thanks to ANK). Make |
46 | * the rates sysctl configurable. |
47 | * Yu Tianli : Fixed two ugly bugs in icmp_send |
48 | * - IP option length was accounted wrongly |
49 | * - ICMP header length was not accounted |
50 | * at all. |
51 | * Tristan Greaves : Added sysctl option to ignore bogus |
52 | * broadcast responses from broken routers. |
53 | * |
54 | * To Fix: |
55 | * |
56 | * - Should use skb_pull() instead of all the manual checking. |
57 | * This would also greatly simply some upper layer error handlers. --AK |
58 | */ |
59 | |
60 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
61 | |
62 | #include <linux/module.h> |
63 | #include <linux/types.h> |
64 | #include <linux/jiffies.h> |
65 | #include <linux/kernel.h> |
66 | #include <linux/fcntl.h> |
67 | #include <linux/socket.h> |
68 | #include <linux/in.h> |
69 | #include <linux/inet.h> |
70 | #include <linux/inetdevice.h> |
71 | #include <linux/netdevice.h> |
72 | #include <linux/string.h> |
73 | #include <linux/netfilter_ipv4.h> |
74 | #include <linux/slab.h> |
75 | #include <net/snmp.h> |
76 | #include <net/ip.h> |
77 | #include <net/route.h> |
78 | #include <net/protocol.h> |
79 | #include <net/icmp.h> |
80 | #include <net/tcp.h> |
81 | #include <net/udp.h> |
82 | #include <net/raw.h> |
83 | #include <net/ping.h> |
84 | #include <linux/skbuff.h> |
85 | #include <net/sock.h> |
86 | #include <linux/errno.h> |
87 | #include <linux/timer.h> |
88 | #include <linux/init.h> |
89 | #include <linux/uaccess.h> |
90 | #include <net/checksum.h> |
91 | #include <net/xfrm.h> |
92 | #include <net/inet_common.h> |
93 | #include <net/ip_fib.h> |
94 | #include <net/l3mdev.h> |
95 | #include <net/addrconf.h> |
96 | #include <net/inet_dscp.h> |
97 | #define CREATE_TRACE_POINTS |
98 | #include <trace/events/icmp.h> |
99 | |
100 | /* |
101 | * Build xmit assembly blocks |
102 | */ |
103 | |
104 | struct icmp_bxm { |
105 | struct sk_buff *skb; |
106 | int offset; |
107 | int data_len; |
108 | |
109 | struct { |
110 | struct icmphdr icmph; |
111 | __be32 times[3]; |
112 | } data; |
113 | int head_len; |
114 | struct ip_options_data replyopts; |
115 | }; |
116 | |
117 | /* An array of errno for error messages from dest unreach. */ |
118 | /* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */ |
119 | |
120 | const struct icmp_err icmp_err_convert[] = { |
121 | { |
122 | .errno = ENETUNREACH, /* ICMP_NET_UNREACH */ |
123 | .fatal = 0, |
124 | }, |
125 | { |
126 | .errno = EHOSTUNREACH, /* ICMP_HOST_UNREACH */ |
127 | .fatal = 0, |
128 | }, |
129 | { |
130 | .errno = ENOPROTOOPT /* ICMP_PROT_UNREACH */, |
131 | .fatal = 1, |
132 | }, |
133 | { |
134 | .errno = ECONNREFUSED, /* ICMP_PORT_UNREACH */ |
135 | .fatal = 1, |
136 | }, |
137 | { |
138 | .errno = EMSGSIZE, /* ICMP_FRAG_NEEDED */ |
139 | .fatal = 0, |
140 | }, |
141 | { |
142 | .errno = EOPNOTSUPP, /* ICMP_SR_FAILED */ |
143 | .fatal = 0, |
144 | }, |
145 | { |
146 | .errno = ENETUNREACH, /* ICMP_NET_UNKNOWN */ |
147 | .fatal = 1, |
148 | }, |
149 | { |
150 | .errno = EHOSTDOWN, /* ICMP_HOST_UNKNOWN */ |
151 | .fatal = 1, |
152 | }, |
153 | { |
154 | .errno = ENONET, /* ICMP_HOST_ISOLATED */ |
155 | .fatal = 1, |
156 | }, |
157 | { |
158 | .errno = ENETUNREACH, /* ICMP_NET_ANO */ |
159 | .fatal = 1, |
160 | }, |
161 | { |
162 | .errno = EHOSTUNREACH, /* ICMP_HOST_ANO */ |
163 | .fatal = 1, |
164 | }, |
165 | { |
166 | .errno = ENETUNREACH, /* ICMP_NET_UNR_TOS */ |
167 | .fatal = 0, |
168 | }, |
169 | { |
170 | .errno = EHOSTUNREACH, /* ICMP_HOST_UNR_TOS */ |
171 | .fatal = 0, |
172 | }, |
173 | { |
174 | .errno = EHOSTUNREACH, /* ICMP_PKT_FILTERED */ |
175 | .fatal = 1, |
176 | }, |
177 | { |
178 | .errno = EHOSTUNREACH, /* ICMP_PREC_VIOLATION */ |
179 | .fatal = 1, |
180 | }, |
181 | { |
182 | .errno = EHOSTUNREACH, /* ICMP_PREC_CUTOFF */ |
183 | .fatal = 1, |
184 | }, |
185 | }; |
186 | EXPORT_SYMBOL(icmp_err_convert); |
187 | |
188 | /* |
189 | * ICMP control array. This specifies what to do with each ICMP. |
190 | */ |
191 | |
192 | struct icmp_control { |
193 | enum skb_drop_reason (*handler)(struct sk_buff *skb); |
194 | short error; /* This ICMP is classed as an error message */ |
195 | }; |
196 | |
197 | static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1]; |
198 | |
199 | static DEFINE_PER_CPU(struct sock *, ipv4_icmp_sk); |
200 | |
201 | /* Called with BH disabled */ |
202 | static inline struct sock *icmp_xmit_lock(struct net *net) |
203 | { |
204 | struct sock *sk; |
205 | |
206 | sk = this_cpu_read(ipv4_icmp_sk); |
207 | |
208 | if (unlikely(!spin_trylock(&sk->sk_lock.slock))) { |
209 | /* This can happen if the output path signals a |
210 | * dst_link_failure() for an outgoing ICMP packet. |
211 | */ |
212 | return NULL; |
213 | } |
214 | sock_net_set(sk, net); |
215 | return sk; |
216 | } |
217 | |
218 | static inline void icmp_xmit_unlock(struct sock *sk) |
219 | { |
220 | sock_net_set(sk, net: &init_net); |
221 | spin_unlock(lock: &sk->sk_lock.slock); |
222 | } |
223 | |
224 | /** |
225 | * icmp_global_allow - Are we allowed to send one more ICMP message ? |
226 | * @net: network namespace |
227 | * |
228 | * Uses a token bucket to limit our ICMP messages to ~sysctl_icmp_msgs_per_sec. |
229 | * Returns false if we reached the limit and can not send another packet. |
230 | * Works in tandem with icmp_global_consume(). |
231 | */ |
232 | bool icmp_global_allow(struct net *net) |
233 | { |
234 | u32 delta, now, oldstamp; |
235 | int incr, new, old; |
236 | |
237 | /* Note: many cpus could find this condition true. |
238 | * Then later icmp_global_consume() could consume more credits, |
239 | * this is an acceptable race. |
240 | */ |
241 | if (atomic_read(v: &net->ipv4.icmp_global_credit) > 0) |
242 | return true; |
243 | |
244 | now = jiffies; |
245 | oldstamp = READ_ONCE(net->ipv4.icmp_global_stamp); |
246 | delta = min_t(u32, now - oldstamp, HZ); |
247 | if (delta < HZ / 50) |
248 | return false; |
249 | |
250 | incr = READ_ONCE(net->ipv4.sysctl_icmp_msgs_per_sec) * delta / HZ; |
251 | if (!incr) |
252 | return false; |
253 | |
254 | if (cmpxchg(&net->ipv4.icmp_global_stamp, oldstamp, now) == oldstamp) { |
255 | old = atomic_read(v: &net->ipv4.icmp_global_credit); |
256 | do { |
257 | new = min(old + incr, READ_ONCE(net->ipv4.sysctl_icmp_msgs_burst)); |
258 | } while (!atomic_try_cmpxchg(v: &net->ipv4.icmp_global_credit, old: &old, new)); |
259 | } |
260 | return true; |
261 | } |
262 | EXPORT_SYMBOL(icmp_global_allow); |
263 | |
264 | void icmp_global_consume(struct net *net) |
265 | { |
266 | int credits = get_random_u32_below(ceil: 3); |
267 | |
268 | /* Note: this might make icmp_global.credit negative. */ |
269 | if (credits) |
270 | atomic_sub(i: credits, v: &net->ipv4.icmp_global_credit); |
271 | } |
272 | EXPORT_SYMBOL(icmp_global_consume); |
273 | |
274 | static bool icmpv4_mask_allow(struct net *net, int type, int code) |
275 | { |
276 | if (type > NR_ICMP_TYPES) |
277 | return true; |
278 | |
279 | /* Don't limit PMTU discovery. */ |
280 | if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) |
281 | return true; |
282 | |
283 | /* Limit if icmp type is enabled in ratemask. */ |
284 | if (!((1 << type) & READ_ONCE(net->ipv4.sysctl_icmp_ratemask))) |
285 | return true; |
286 | |
287 | return false; |
288 | } |
289 | |
290 | static bool icmpv4_global_allow(struct net *net, int type, int code, |
291 | bool *apply_ratelimit) |
292 | { |
293 | if (icmpv4_mask_allow(net, type, code)) |
294 | return true; |
295 | |
296 | if (icmp_global_allow(net)) { |
297 | *apply_ratelimit = true; |
298 | return true; |
299 | } |
300 | __ICMP_INC_STATS(net, ICMP_MIB_RATELIMITGLOBAL); |
301 | return false; |
302 | } |
303 | |
304 | /* |
305 | * Send an ICMP frame. |
306 | */ |
307 | |
308 | static bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt, |
309 | struct flowi4 *fl4, int type, int code, |
310 | bool apply_ratelimit) |
311 | { |
312 | struct dst_entry *dst = &rt->dst; |
313 | struct inet_peer *peer; |
314 | bool rc = true; |
315 | |
316 | if (!apply_ratelimit) |
317 | return true; |
318 | |
319 | /* No rate limit on loopback */ |
320 | if (dst->dev && (dst->dev->flags&IFF_LOOPBACK)) |
321 | goto out; |
322 | |
323 | rcu_read_lock(); |
324 | peer = inet_getpeer_v4(base: net->ipv4.peers, v4daddr: fl4->daddr, |
325 | vif: l3mdev_master_ifindex_rcu(dev: dst->dev)); |
326 | rc = inet_peer_xrlim_allow(peer, |
327 | READ_ONCE(net->ipv4.sysctl_icmp_ratelimit)); |
328 | rcu_read_unlock(); |
329 | out: |
330 | if (!rc) |
331 | __ICMP_INC_STATS(net, ICMP_MIB_RATELIMITHOST); |
332 | else |
333 | icmp_global_consume(net); |
334 | return rc; |
335 | } |
336 | |
337 | /* |
338 | * Maintain the counters used in the SNMP statistics for outgoing ICMP |
339 | */ |
340 | void icmp_out_count(struct net *net, unsigned char type) |
341 | { |
342 | ICMPMSGOUT_INC_STATS(net, type); |
343 | ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS); |
344 | } |
345 | |
346 | /* |
347 | * Checksum each fragment, and on the first include the headers and final |
348 | * checksum. |
349 | */ |
350 | static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd, |
351 | struct sk_buff *skb) |
352 | { |
353 | struct icmp_bxm *icmp_param = from; |
354 | __wsum csum; |
355 | |
356 | csum = skb_copy_and_csum_bits(skb: icmp_param->skb, |
357 | offset: icmp_param->offset + offset, |
358 | to, len); |
359 | |
360 | skb->csum = csum_block_add(csum: skb->csum, csum2: csum, offset: odd); |
361 | if (icmp_pointers[icmp_param->data.icmph.type].error) |
362 | nf_ct_attach(skb, icmp_param->skb); |
363 | return 0; |
364 | } |
365 | |
366 | static void icmp_push_reply(struct sock *sk, |
367 | struct icmp_bxm *icmp_param, |
368 | struct flowi4 *fl4, |
369 | struct ipcm_cookie *ipc, struct rtable **rt) |
370 | { |
371 | struct sk_buff *skb; |
372 | |
373 | if (ip_append_data(sk, fl4, getfrag: icmp_glue_bits, from: icmp_param, |
374 | len: icmp_param->data_len+icmp_param->head_len, |
375 | protolen: icmp_param->head_len, |
376 | ipc, rt, MSG_DONTWAIT) < 0) { |
377 | __ICMP_INC_STATS(sock_net(sk), ICMP_MIB_OUTERRORS); |
378 | ip_flush_pending_frames(sk); |
379 | } else if ((skb = skb_peek(list_: &sk->sk_write_queue)) != NULL) { |
380 | struct icmphdr *icmph = icmp_hdr(skb); |
381 | __wsum csum; |
382 | struct sk_buff *skb1; |
383 | |
384 | csum = csum_partial_copy_nocheck(src: (void *)&icmp_param->data, |
385 | dst: (char *)icmph, |
386 | len: icmp_param->head_len); |
387 | skb_queue_walk(&sk->sk_write_queue, skb1) { |
388 | csum = csum_add(csum, addend: skb1->csum); |
389 | } |
390 | icmph->checksum = csum_fold(csum); |
391 | skb->ip_summed = CHECKSUM_NONE; |
392 | ip_push_pending_frames(sk, fl4); |
393 | } |
394 | } |
395 | |
396 | /* |
397 | * Driving logic for building and sending ICMP messages. |
398 | */ |
399 | |
400 | static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb) |
401 | { |
402 | struct rtable *rt = skb_rtable(skb); |
403 | struct net *net = dev_net_rcu(dev: rt->dst.dev); |
404 | bool apply_ratelimit = false; |
405 | struct ipcm_cookie ipc; |
406 | struct flowi4 fl4; |
407 | struct sock *sk; |
408 | __be32 daddr, saddr; |
409 | u32 mark = IP4_REPLY_MARK(net, skb->mark); |
410 | int type = icmp_param->data.icmph.type; |
411 | int code = icmp_param->data.icmph.code; |
412 | |
413 | if (ip_options_echo(net, dopt: &icmp_param->replyopts.opt.opt, skb)) |
414 | return; |
415 | |
416 | /* Needed by both icmpv4_global_allow and icmp_xmit_lock */ |
417 | local_bh_disable(); |
418 | |
419 | /* is global icmp_msgs_per_sec exhausted ? */ |
420 | if (!icmpv4_global_allow(net, type, code, apply_ratelimit: &apply_ratelimit)) |
421 | goto out_bh_enable; |
422 | |
423 | sk = icmp_xmit_lock(net); |
424 | if (!sk) |
425 | goto out_bh_enable; |
426 | |
427 | icmp_param->data.icmph.checksum = 0; |
428 | |
429 | ipcm_init(ipcm: &ipc); |
430 | ipc.tos = ip_hdr(skb)->tos; |
431 | ipc.sockc.mark = mark; |
432 | daddr = ipc.addr = ip_hdr(skb)->saddr; |
433 | saddr = fib_compute_spec_dst(skb); |
434 | |
435 | if (icmp_param->replyopts.opt.opt.optlen) { |
436 | ipc.opt = &icmp_param->replyopts.opt; |
437 | if (ipc.opt->opt.srr) |
438 | daddr = icmp_param->replyopts.opt.opt.faddr; |
439 | } |
440 | memset(&fl4, 0, sizeof(fl4)); |
441 | fl4.daddr = daddr; |
442 | fl4.saddr = saddr; |
443 | fl4.flowi4_mark = mark; |
444 | fl4.flowi4_uid = sock_net_uid(net, NULL); |
445 | fl4.flowi4_tos = inet_dscp_to_dsfield(dscp: ip4h_dscp(ip4h: ip_hdr(skb))); |
446 | fl4.flowi4_proto = IPPROTO_ICMP; |
447 | fl4.flowi4_oif = l3mdev_master_ifindex(dev: skb->dev); |
448 | security_skb_classify_flow(skb, flic: flowi4_to_flowi_common(fl4: &fl4)); |
449 | rt = ip_route_output_key(net, flp: &fl4); |
450 | if (IS_ERR(ptr: rt)) |
451 | goto out_unlock; |
452 | if (icmpv4_xrlim_allow(net, rt, fl4: &fl4, type, code, apply_ratelimit)) |
453 | icmp_push_reply(sk, icmp_param, fl4: &fl4, ipc: &ipc, rt: &rt); |
454 | ip_rt_put(rt); |
455 | out_unlock: |
456 | icmp_xmit_unlock(sk); |
457 | out_bh_enable: |
458 | local_bh_enable(); |
459 | } |
460 | |
461 | /* |
462 | * The device used for looking up which routing table to use for sending an ICMP |
463 | * error is preferably the source whenever it is set, which should ensure the |
464 | * icmp error can be sent to the source host, else lookup using the routing |
465 | * table of the destination device, else use the main routing table (index 0). |
466 | */ |
467 | static struct net_device *icmp_get_route_lookup_dev(struct sk_buff *skb) |
468 | { |
469 | struct net_device *route_lookup_dev = NULL; |
470 | |
471 | if (skb->dev) |
472 | route_lookup_dev = skb->dev; |
473 | else if (skb_dst(skb)) |
474 | route_lookup_dev = skb_dst(skb)->dev; |
475 | return route_lookup_dev; |
476 | } |
477 | |
478 | static struct rtable *icmp_route_lookup(struct net *net, struct flowi4 *fl4, |
479 | struct sk_buff *skb_in, |
480 | const struct iphdr *iph, __be32 saddr, |
481 | dscp_t dscp, u32 mark, int type, |
482 | int code, struct icmp_bxm *param) |
483 | { |
484 | struct net_device *route_lookup_dev; |
485 | struct dst_entry *dst, *dst2; |
486 | struct rtable *rt, *rt2; |
487 | struct flowi4 fl4_dec; |
488 | int err; |
489 | |
490 | memset(fl4, 0, sizeof(*fl4)); |
491 | fl4->daddr = (param->replyopts.opt.opt.srr ? |
492 | param->replyopts.opt.opt.faddr : iph->saddr); |
493 | fl4->saddr = saddr; |
494 | fl4->flowi4_mark = mark; |
495 | fl4->flowi4_uid = sock_net_uid(net, NULL); |
496 | fl4->flowi4_tos = inet_dscp_to_dsfield(dscp); |
497 | fl4->flowi4_proto = IPPROTO_ICMP; |
498 | fl4->fl4_icmp_type = type; |
499 | fl4->fl4_icmp_code = code; |
500 | route_lookup_dev = icmp_get_route_lookup_dev(skb: skb_in); |
501 | fl4->flowi4_oif = l3mdev_master_ifindex(dev: route_lookup_dev); |
502 | |
503 | security_skb_classify_flow(skb: skb_in, flic: flowi4_to_flowi_common(fl4)); |
504 | rt = ip_route_output_key_hash(net, flp: fl4, skb: skb_in); |
505 | if (IS_ERR(ptr: rt)) |
506 | return rt; |
507 | |
508 | /* No need to clone since we're just using its address. */ |
509 | rt2 = rt; |
510 | |
511 | dst = xfrm_lookup(net, dst_orig: &rt->dst, |
512 | fl: flowi4_to_flowi(fl4), NULL, flags: 0); |
513 | rt = dst_rtable(dst); |
514 | if (!IS_ERR(ptr: dst)) { |
515 | if (rt != rt2) |
516 | return rt; |
517 | if (inet_addr_type_dev_table(net, dev: route_lookup_dev, |
518 | addr: fl4->daddr) == RTN_LOCAL) |
519 | return rt; |
520 | } else if (PTR_ERR(ptr: dst) == -EPERM) { |
521 | rt = NULL; |
522 | } else { |
523 | return rt; |
524 | } |
525 | err = xfrm_decode_session_reverse(net, skb: skb_in, fl: flowi4_to_flowi(fl4: &fl4_dec), AF_INET); |
526 | if (err) |
527 | goto relookup_failed; |
528 | |
529 | if (inet_addr_type_dev_table(net, dev: route_lookup_dev, |
530 | addr: fl4_dec.saddr) == RTN_LOCAL) { |
531 | rt2 = __ip_route_output_key(net, flp: &fl4_dec); |
532 | if (IS_ERR(ptr: rt2)) |
533 | err = PTR_ERR(ptr: rt2); |
534 | } else { |
535 | struct flowi4 fl4_2 = {}; |
536 | unsigned long orefdst; |
537 | |
538 | fl4_2.daddr = fl4_dec.saddr; |
539 | rt2 = ip_route_output_key(net, flp: &fl4_2); |
540 | if (IS_ERR(ptr: rt2)) { |
541 | err = PTR_ERR(ptr: rt2); |
542 | goto relookup_failed; |
543 | } |
544 | /* Ugh! */ |
545 | orefdst = skb_in->_skb_refdst; /* save old refdst */ |
546 | skb_dst_set(skb: skb_in, NULL); |
547 | err = ip_route_input(skb: skb_in, dst: fl4_dec.daddr, src: fl4_dec.saddr, |
548 | dscp, devin: rt2->dst.dev) ? -EINVAL : 0; |
549 | |
550 | dst_release(dst: &rt2->dst); |
551 | rt2 = skb_rtable(skb: skb_in); |
552 | skb_in->_skb_refdst = orefdst; /* restore old refdst */ |
553 | } |
554 | |
555 | if (err) |
556 | goto relookup_failed; |
557 | |
558 | dst2 = xfrm_lookup(net, dst_orig: &rt2->dst, fl: flowi4_to_flowi(fl4: &fl4_dec), NULL, |
559 | flags: XFRM_LOOKUP_ICMP); |
560 | rt2 = dst_rtable(dst2); |
561 | if (!IS_ERR(ptr: dst2)) { |
562 | dst_release(dst: &rt->dst); |
563 | memcpy(fl4, &fl4_dec, sizeof(*fl4)); |
564 | rt = rt2; |
565 | } else if (PTR_ERR(ptr: dst2) == -EPERM) { |
566 | if (rt) |
567 | dst_release(dst: &rt->dst); |
568 | return rt2; |
569 | } else { |
570 | err = PTR_ERR(ptr: dst2); |
571 | goto relookup_failed; |
572 | } |
573 | return rt; |
574 | |
575 | relookup_failed: |
576 | if (rt) |
577 | return rt; |
578 | return ERR_PTR(error: err); |
579 | } |
580 | |
581 | /* |
582 | * Send an ICMP message in response to a situation |
583 | * |
584 | * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. |
585 | * MAY send more (we do). |
586 | * MUST NOT change this header information. |
587 | * MUST NOT reply to a multicast/broadcast IP address. |
588 | * MUST NOT reply to a multicast/broadcast MAC address. |
589 | * MUST reply to only the first fragment. |
590 | */ |
591 | |
592 | void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info, |
593 | const struct ip_options *opt) |
594 | { |
595 | struct iphdr *iph; |
596 | int room; |
597 | struct icmp_bxm icmp_param; |
598 | struct rtable *rt = skb_rtable(skb: skb_in); |
599 | bool apply_ratelimit = false; |
600 | struct ipcm_cookie ipc; |
601 | struct flowi4 fl4; |
602 | __be32 saddr; |
603 | u8 tos; |
604 | u32 mark; |
605 | struct net *net; |
606 | struct sock *sk; |
607 | |
608 | if (!rt) |
609 | return; |
610 | |
611 | rcu_read_lock(); |
612 | |
613 | if (rt->dst.dev) |
614 | net = dev_net_rcu(dev: rt->dst.dev); |
615 | else if (skb_in->dev) |
616 | net = dev_net_rcu(dev: skb_in->dev); |
617 | else |
618 | goto out; |
619 | |
620 | /* |
621 | * Find the original header. It is expected to be valid, of course. |
622 | * Check this, icmp_send is called from the most obscure devices |
623 | * sometimes. |
624 | */ |
625 | iph = ip_hdr(skb: skb_in); |
626 | |
627 | if ((u8 *)iph < skb_in->head || |
628 | (skb_network_header(skb: skb_in) + sizeof(*iph)) > |
629 | skb_tail_pointer(skb: skb_in)) |
630 | goto out; |
631 | |
632 | /* |
633 | * No replies to physical multicast/broadcast |
634 | */ |
635 | if (skb_in->pkt_type != PACKET_HOST) |
636 | goto out; |
637 | |
638 | /* |
639 | * Now check at the protocol level |
640 | */ |
641 | if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) |
642 | goto out; |
643 | |
644 | /* |
645 | * Only reply to fragment 0. We byte re-order the constant |
646 | * mask for efficiency. |
647 | */ |
648 | if (iph->frag_off & htons(IP_OFFSET)) |
649 | goto out; |
650 | |
651 | /* |
652 | * If we send an ICMP error to an ICMP error a mess would result.. |
653 | */ |
654 | if (icmp_pointers[type].error) { |
655 | /* |
656 | * We are an error, check if we are replying to an |
657 | * ICMP error |
658 | */ |
659 | if (iph->protocol == IPPROTO_ICMP) { |
660 | u8 _inner_type, *itp; |
661 | |
662 | itp = skb_header_pointer(skb: skb_in, |
663 | offset: skb_network_header(skb: skb_in) + |
664 | (iph->ihl << 2) + |
665 | offsetof(struct icmphdr, |
666 | type) - |
667 | skb_in->data, |
668 | len: sizeof(_inner_type), |
669 | buffer: &_inner_type); |
670 | if (!itp) |
671 | goto out; |
672 | |
673 | /* |
674 | * Assume any unknown ICMP type is an error. This |
675 | * isn't specified by the RFC, but think about it.. |
676 | */ |
677 | if (*itp > NR_ICMP_TYPES || |
678 | icmp_pointers[*itp].error) |
679 | goto out; |
680 | } |
681 | } |
682 | |
683 | /* Needed by both icmpv4_global_allow and icmp_xmit_lock */ |
684 | local_bh_disable(); |
685 | |
686 | /* Check global sysctl_icmp_msgs_per_sec ratelimit, unless |
687 | * incoming dev is loopback. If outgoing dev change to not be |
688 | * loopback, then peer ratelimit still work (in icmpv4_xrlim_allow) |
689 | */ |
690 | if (!(skb_in->dev && (skb_in->dev->flags&IFF_LOOPBACK)) && |
691 | !icmpv4_global_allow(net, type, code, apply_ratelimit: &apply_ratelimit)) |
692 | goto out_bh_enable; |
693 | |
694 | sk = icmp_xmit_lock(net); |
695 | if (!sk) |
696 | goto out_bh_enable; |
697 | |
698 | /* |
699 | * Construct source address and options. |
700 | */ |
701 | |
702 | saddr = iph->daddr; |
703 | if (!(rt->rt_flags & RTCF_LOCAL)) { |
704 | struct net_device *dev = NULL; |
705 | |
706 | rcu_read_lock(); |
707 | if (rt_is_input_route(rt) && |
708 | READ_ONCE(net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)) |
709 | dev = dev_get_by_index_rcu(net, ifindex: inet_iif(skb: skb_in)); |
710 | |
711 | if (dev) |
712 | saddr = inet_select_addr(dev, dst: iph->saddr, |
713 | scope: RT_SCOPE_LINK); |
714 | else |
715 | saddr = 0; |
716 | rcu_read_unlock(); |
717 | } |
718 | |
719 | tos = icmp_pointers[type].error ? (RT_TOS(iph->tos) | |
720 | IPTOS_PREC_INTERNETCONTROL) : |
721 | iph->tos; |
722 | mark = IP4_REPLY_MARK(net, skb_in->mark); |
723 | |
724 | if (__ip_options_echo(net, dopt: &icmp_param.replyopts.opt.opt, skb: skb_in, sopt: opt)) |
725 | goto out_unlock; |
726 | |
727 | |
728 | /* |
729 | * Prepare data for ICMP header. |
730 | */ |
731 | |
732 | icmp_param.data.icmph.type = type; |
733 | icmp_param.data.icmph.code = code; |
734 | icmp_param.data.icmph.un.gateway = info; |
735 | icmp_param.data.icmph.checksum = 0; |
736 | icmp_param.skb = skb_in; |
737 | icmp_param.offset = skb_network_offset(skb: skb_in); |
738 | ipcm_init(ipcm: &ipc); |
739 | ipc.tos = tos; |
740 | ipc.addr = iph->saddr; |
741 | ipc.opt = &icmp_param.replyopts.opt; |
742 | ipc.sockc.mark = mark; |
743 | |
744 | rt = icmp_route_lookup(net, fl4: &fl4, skb_in, iph, saddr, |
745 | dscp: inet_dsfield_to_dscp(dsfield: tos), mark, type, code, |
746 | param: &icmp_param); |
747 | if (IS_ERR(ptr: rt)) |
748 | goto out_unlock; |
749 | |
750 | /* peer icmp_ratelimit */ |
751 | if (!icmpv4_xrlim_allow(net, rt, fl4: &fl4, type, code, apply_ratelimit)) |
752 | goto ende; |
753 | |
754 | /* RFC says return as much as we can without exceeding 576 bytes. */ |
755 | |
756 | room = dst_mtu(dst: &rt->dst); |
757 | if (room > 576) |
758 | room = 576; |
759 | room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen; |
760 | room -= sizeof(struct icmphdr); |
761 | /* Guard against tiny mtu. We need to include at least one |
762 | * IP network header for this message to make any sense. |
763 | */ |
764 | if (room <= (int)sizeof(struct iphdr)) |
765 | goto ende; |
766 | |
767 | icmp_param.data_len = skb_in->len - icmp_param.offset; |
768 | if (icmp_param.data_len > room) |
769 | icmp_param.data_len = room; |
770 | icmp_param.head_len = sizeof(struct icmphdr); |
771 | |
772 | /* if we don't have a source address at this point, fall back to the |
773 | * dummy address instead of sending out a packet with a source address |
774 | * of 0.0.0.0 |
775 | */ |
776 | if (!fl4.saddr) |
777 | fl4.saddr = htonl(INADDR_DUMMY); |
778 | |
779 | trace_icmp_send(skb: skb_in, type, code); |
780 | |
781 | icmp_push_reply(sk, icmp_param: &icmp_param, fl4: &fl4, ipc: &ipc, rt: &rt); |
782 | ende: |
783 | ip_rt_put(rt); |
784 | out_unlock: |
785 | icmp_xmit_unlock(sk); |
786 | out_bh_enable: |
787 | local_bh_enable(); |
788 | out: |
789 | rcu_read_unlock(); |
790 | } |
791 | EXPORT_SYMBOL(__icmp_send); |
792 | |
793 | #if IS_ENABLED(CONFIG_NF_NAT) |
794 | #include <net/netfilter/nf_conntrack.h> |
795 | void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info) |
796 | { |
797 | struct sk_buff *cloned_skb = NULL; |
798 | struct ip_options opts = { 0 }; |
799 | enum ip_conntrack_info ctinfo; |
800 | struct nf_conn *ct; |
801 | __be32 orig_ip; |
802 | |
803 | ct = nf_ct_get(skb: skb_in, ctinfo: &ctinfo); |
804 | if (!ct || !(ct->status & IPS_SRC_NAT)) { |
805 | __icmp_send(skb_in, type, code, info, &opts); |
806 | return; |
807 | } |
808 | |
809 | if (skb_shared(skb: skb_in)) |
810 | skb_in = cloned_skb = skb_clone(skb: skb_in, GFP_ATOMIC); |
811 | |
812 | if (unlikely(!skb_in || skb_network_header(skb_in) < skb_in->head || |
813 | (skb_network_header(skb_in) + sizeof(struct iphdr)) > |
814 | skb_tail_pointer(skb_in) || skb_ensure_writable(skb_in, |
815 | skb_network_offset(skb_in) + sizeof(struct iphdr)))) |
816 | goto out; |
817 | |
818 | orig_ip = ip_hdr(skb: skb_in)->saddr; |
819 | ip_hdr(skb: skb_in)->saddr = ct->tuplehash[0].tuple.src.u3.ip; |
820 | __icmp_send(skb_in, type, code, info, &opts); |
821 | ip_hdr(skb: skb_in)->saddr = orig_ip; |
822 | out: |
823 | consume_skb(skb: cloned_skb); |
824 | } |
825 | EXPORT_SYMBOL(icmp_ndo_send); |
826 | #endif |
827 | |
828 | static void icmp_socket_deliver(struct sk_buff *skb, u32 info) |
829 | { |
830 | const struct iphdr *iph = (const struct iphdr *)skb->data; |
831 | const struct net_protocol *ipprot; |
832 | int protocol = iph->protocol; |
833 | |
834 | /* Checkin full IP header plus 8 bytes of protocol to |
835 | * avoid additional coding at protocol handlers. |
836 | */ |
837 | if (!pskb_may_pull(skb, len: iph->ihl * 4 + 8)) { |
838 | __ICMP_INC_STATS(dev_net_rcu(skb->dev), ICMP_MIB_INERRORS); |
839 | return; |
840 | } |
841 | |
842 | raw_icmp_error(skb, protocol, info); |
843 | |
844 | ipprot = rcu_dereference(inet_protos[protocol]); |
845 | if (ipprot && ipprot->err_handler) |
846 | ipprot->err_handler(skb, info); |
847 | } |
848 | |
849 | static bool icmp_tag_validation(int proto) |
850 | { |
851 | bool ok; |
852 | |
853 | rcu_read_lock(); |
854 | ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation; |
855 | rcu_read_unlock(); |
856 | return ok; |
857 | } |
858 | |
859 | /* |
860 | * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEEDED, ICMP_QUENCH, and |
861 | * ICMP_PARAMETERPROB. |
862 | */ |
863 | |
864 | static enum skb_drop_reason icmp_unreach(struct sk_buff *skb) |
865 | { |
866 | enum skb_drop_reason reason = SKB_NOT_DROPPED_YET; |
867 | const struct iphdr *iph; |
868 | struct icmphdr *icmph; |
869 | struct net *net; |
870 | u32 info = 0; |
871 | |
872 | net = dev_net_rcu(dev: skb_dst(skb)->dev); |
873 | |
874 | /* |
875 | * Incomplete header ? |
876 | * Only checks for the IP header, there should be an |
877 | * additional check for longer headers in upper levels. |
878 | */ |
879 | |
880 | if (!pskb_may_pull(skb, len: sizeof(struct iphdr))) |
881 | goto out_err; |
882 | |
883 | icmph = icmp_hdr(skb); |
884 | iph = (const struct iphdr *)skb->data; |
885 | |
886 | if (iph->ihl < 5) { /* Mangled header, drop. */ |
887 | reason = SKB_DROP_REASON_IP_INHDR; |
888 | goto out_err; |
889 | } |
890 | |
891 | switch (icmph->type) { |
892 | case ICMP_DEST_UNREACH: |
893 | switch (icmph->code & 15) { |
894 | case ICMP_NET_UNREACH: |
895 | case ICMP_HOST_UNREACH: |
896 | case ICMP_PROT_UNREACH: |
897 | case ICMP_PORT_UNREACH: |
898 | break; |
899 | case ICMP_FRAG_NEEDED: |
900 | /* for documentation of the ip_no_pmtu_disc |
901 | * values please see |
902 | * Documentation/networking/ip-sysctl.rst |
903 | */ |
904 | switch (READ_ONCE(net->ipv4.sysctl_ip_no_pmtu_disc)) { |
905 | default: |
906 | net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n", |
907 | &iph->daddr); |
908 | break; |
909 | case 2: |
910 | goto out; |
911 | case 3: |
912 | if (!icmp_tag_validation(proto: iph->protocol)) |
913 | goto out; |
914 | fallthrough; |
915 | case 0: |
916 | info = ntohs(icmph->un.frag.mtu); |
917 | } |
918 | break; |
919 | case ICMP_SR_FAILED: |
920 | net_dbg_ratelimited("%pI4: Source Route Failed\n", |
921 | &iph->daddr); |
922 | break; |
923 | default: |
924 | break; |
925 | } |
926 | if (icmph->code > NR_ICMP_UNREACH) |
927 | goto out; |
928 | break; |
929 | case ICMP_PARAMETERPROB: |
930 | info = ntohl(icmph->un.gateway) >> 24; |
931 | break; |
932 | case ICMP_TIME_EXCEEDED: |
933 | __ICMP_INC_STATS(net, ICMP_MIB_INTIMEEXCDS); |
934 | if (icmph->code == ICMP_EXC_FRAGTIME) |
935 | goto out; |
936 | break; |
937 | } |
938 | |
939 | /* |
940 | * Throw it at our lower layers |
941 | * |
942 | * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed |
943 | * header. |
944 | * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the |
945 | * transport layer. |
946 | * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to |
947 | * transport layer. |
948 | */ |
949 | |
950 | /* |
951 | * Check the other end isn't violating RFC 1122. Some routers send |
952 | * bogus responses to broadcast frames. If you see this message |
953 | * first check your netmask matches at both ends, if it does then |
954 | * get the other vendor to fix their kit. |
955 | */ |
956 | |
957 | if (!READ_ONCE(net->ipv4.sysctl_icmp_ignore_bogus_error_responses) && |
958 | inet_addr_type_dev_table(net, dev: skb->dev, addr: iph->daddr) == RTN_BROADCAST) { |
959 | net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n", |
960 | &ip_hdr(skb)->saddr, |
961 | icmph->type, icmph->code, |
962 | &iph->daddr, skb->dev->name); |
963 | goto out; |
964 | } |
965 | |
966 | icmp_socket_deliver(skb, info); |
967 | |
968 | out: |
969 | return reason; |
970 | out_err: |
971 | __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); |
972 | return reason ?: SKB_DROP_REASON_NOT_SPECIFIED; |
973 | } |
974 | |
975 | |
976 | /* |
977 | * Handle ICMP_REDIRECT. |
978 | */ |
979 | |
980 | static enum skb_drop_reason icmp_redirect(struct sk_buff *skb) |
981 | { |
982 | if (skb->len < sizeof(struct iphdr)) { |
983 | __ICMP_INC_STATS(dev_net_rcu(skb->dev), ICMP_MIB_INERRORS); |
984 | return SKB_DROP_REASON_PKT_TOO_SMALL; |
985 | } |
986 | |
987 | if (!pskb_may_pull(skb, len: sizeof(struct iphdr))) { |
988 | /* there aught to be a stat */ |
989 | return SKB_DROP_REASON_NOMEM; |
990 | } |
991 | |
992 | icmp_socket_deliver(skb, ntohl(icmp_hdr(skb)->un.gateway)); |
993 | return SKB_NOT_DROPPED_YET; |
994 | } |
995 | |
996 | /* |
997 | * Handle ICMP_ECHO ("ping") and ICMP_EXT_ECHO ("PROBE") requests. |
998 | * |
999 | * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo |
1000 | * requests. |
1001 | * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be |
1002 | * included in the reply. |
1003 | * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring |
1004 | * echo requests, MUST have default=NOT. |
1005 | * RFC 8335: 8 MUST have a config option to enable/disable ICMP |
1006 | * Extended Echo Functionality, MUST be disabled by default |
1007 | * See also WRT handling of options once they are done and working. |
1008 | */ |
1009 | |
1010 | static enum skb_drop_reason icmp_echo(struct sk_buff *skb) |
1011 | { |
1012 | struct icmp_bxm icmp_param; |
1013 | struct net *net; |
1014 | |
1015 | net = dev_net_rcu(dev: skb_dst(skb)->dev); |
1016 | /* should there be an ICMP stat for ignored echos? */ |
1017 | if (READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_all)) |
1018 | return SKB_NOT_DROPPED_YET; |
1019 | |
1020 | icmp_param.data.icmph = *icmp_hdr(skb); |
1021 | icmp_param.skb = skb; |
1022 | icmp_param.offset = 0; |
1023 | icmp_param.data_len = skb->len; |
1024 | icmp_param.head_len = sizeof(struct icmphdr); |
1025 | |
1026 | if (icmp_param.data.icmph.type == ICMP_ECHO) |
1027 | icmp_param.data.icmph.type = ICMP_ECHOREPLY; |
1028 | else if (!icmp_build_probe(skb, icmphdr: &icmp_param.data.icmph)) |
1029 | return SKB_NOT_DROPPED_YET; |
1030 | |
1031 | icmp_reply(icmp_param: &icmp_param, skb); |
1032 | return SKB_NOT_DROPPED_YET; |
1033 | } |
1034 | |
1035 | /* Helper for icmp_echo and icmpv6_echo_reply. |
1036 | * Searches for net_device that matches PROBE interface identifier |
1037 | * and builds PROBE reply message in icmphdr. |
1038 | * |
1039 | * Returns false if PROBE responses are disabled via sysctl |
1040 | */ |
1041 | |
1042 | bool icmp_build_probe(struct sk_buff *skb, struct icmphdr *icmphdr) |
1043 | { |
1044 | struct net *net = dev_net_rcu(dev: skb->dev); |
1045 | struct icmp_ext_hdr *ext_hdr, _ext_hdr; |
1046 | struct icmp_ext_echo_iio *iio, _iio; |
1047 | struct inet6_dev *in6_dev; |
1048 | struct in_device *in_dev; |
1049 | struct net_device *dev; |
1050 | char buff[IFNAMSIZ]; |
1051 | u16 ident_len; |
1052 | u8 status; |
1053 | |
1054 | if (!READ_ONCE(net->ipv4.sysctl_icmp_echo_enable_probe)) |
1055 | return false; |
1056 | |
1057 | /* We currently only support probing interfaces on the proxy node |
1058 | * Check to ensure L-bit is set |
1059 | */ |
1060 | if (!(ntohs(icmphdr->un.echo.sequence) & 1)) |
1061 | return false; |
1062 | /* Clear status bits in reply message */ |
1063 | icmphdr->un.echo.sequence &= htons(0xFF00); |
1064 | if (icmphdr->type == ICMP_EXT_ECHO) |
1065 | icmphdr->type = ICMP_EXT_ECHOREPLY; |
1066 | else |
1067 | icmphdr->type = ICMPV6_EXT_ECHO_REPLY; |
1068 | ext_hdr = skb_header_pointer(skb, offset: 0, len: sizeof(_ext_hdr), buffer: &_ext_hdr); |
1069 | /* Size of iio is class_type dependent. |
1070 | * Only check header here and assign length based on ctype in the switch statement |
1071 | */ |
1072 | iio = skb_header_pointer(skb, offset: sizeof(_ext_hdr), len: sizeof(iio->extobj_hdr), buffer: &_iio); |
1073 | if (!ext_hdr || !iio) |
1074 | goto send_mal_query; |
1075 | if (ntohs(iio->extobj_hdr.length) <= sizeof(iio->extobj_hdr) || |
1076 | ntohs(iio->extobj_hdr.length) > sizeof(_iio)) |
1077 | goto send_mal_query; |
1078 | ident_len = ntohs(iio->extobj_hdr.length) - sizeof(iio->extobj_hdr); |
1079 | iio = skb_header_pointer(skb, offset: sizeof(_ext_hdr), |
1080 | len: sizeof(iio->extobj_hdr) + ident_len, buffer: &_iio); |
1081 | if (!iio) |
1082 | goto send_mal_query; |
1083 | |
1084 | status = 0; |
1085 | dev = NULL; |
1086 | switch (iio->extobj_hdr.class_type) { |
1087 | case ICMP_EXT_ECHO_CTYPE_NAME: |
1088 | if (ident_len >= IFNAMSIZ) |
1089 | goto send_mal_query; |
1090 | memset(buff, 0, sizeof(buff)); |
1091 | memcpy(buff, &iio->ident.name, ident_len); |
1092 | dev = dev_get_by_name(net, name: buff); |
1093 | break; |
1094 | case ICMP_EXT_ECHO_CTYPE_INDEX: |
1095 | if (ident_len != sizeof(iio->ident.ifindex)) |
1096 | goto send_mal_query; |
1097 | dev = dev_get_by_index(net, ntohl(iio->ident.ifindex)); |
1098 | break; |
1099 | case ICMP_EXT_ECHO_CTYPE_ADDR: |
1100 | if (ident_len < sizeof(iio->ident.addr.ctype3_hdr) || |
1101 | ident_len != sizeof(iio->ident.addr.ctype3_hdr) + |
1102 | iio->ident.addr.ctype3_hdr.addrlen) |
1103 | goto send_mal_query; |
1104 | switch (ntohs(iio->ident.addr.ctype3_hdr.afi)) { |
1105 | case ICMP_AFI_IP: |
1106 | if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in_addr)) |
1107 | goto send_mal_query; |
1108 | dev = ip_dev_find(net, addr: iio->ident.addr.ip_addr.ipv4_addr); |
1109 | break; |
1110 | #if IS_ENABLED(CONFIG_IPV6) |
1111 | case ICMP_AFI_IP6: |
1112 | if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in6_addr)) |
1113 | goto send_mal_query; |
1114 | dev = ipv6_stub->ipv6_dev_find(net, &iio->ident.addr.ip_addr.ipv6_addr, dev); |
1115 | dev_hold(dev); |
1116 | break; |
1117 | #endif |
1118 | default: |
1119 | goto send_mal_query; |
1120 | } |
1121 | break; |
1122 | default: |
1123 | goto send_mal_query; |
1124 | } |
1125 | if (!dev) { |
1126 | icmphdr->code = ICMP_EXT_CODE_NO_IF; |
1127 | return true; |
1128 | } |
1129 | /* Fill bits in reply message */ |
1130 | if (dev->flags & IFF_UP) |
1131 | status |= ICMP_EXT_ECHOREPLY_ACTIVE; |
1132 | |
1133 | in_dev = __in_dev_get_rcu(dev); |
1134 | if (in_dev && rcu_access_pointer(in_dev->ifa_list)) |
1135 | status |= ICMP_EXT_ECHOREPLY_IPV4; |
1136 | |
1137 | in6_dev = __in6_dev_get(dev); |
1138 | if (in6_dev && !list_empty(head: &in6_dev->addr_list)) |
1139 | status |= ICMP_EXT_ECHOREPLY_IPV6; |
1140 | |
1141 | dev_put(dev); |
1142 | icmphdr->un.echo.sequence |= htons(status); |
1143 | return true; |
1144 | send_mal_query: |
1145 | icmphdr->code = ICMP_EXT_CODE_MAL_QUERY; |
1146 | return true; |
1147 | } |
1148 | EXPORT_SYMBOL_GPL(icmp_build_probe); |
1149 | |
1150 | /* |
1151 | * Handle ICMP Timestamp requests. |
1152 | * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests. |
1153 | * SHOULD be in the kernel for minimum random latency. |
1154 | * MUST be accurate to a few minutes. |
1155 | * MUST be updated at least at 15Hz. |
1156 | */ |
1157 | static enum skb_drop_reason icmp_timestamp(struct sk_buff *skb) |
1158 | { |
1159 | struct icmp_bxm icmp_param; |
1160 | /* |
1161 | * Too short. |
1162 | */ |
1163 | if (skb->len < 4) |
1164 | goto out_err; |
1165 | |
1166 | /* |
1167 | * Fill in the current time as ms since midnight UT: |
1168 | */ |
1169 | icmp_param.data.times[1] = inet_current_timestamp(); |
1170 | icmp_param.data.times[2] = icmp_param.data.times[1]; |
1171 | |
1172 | BUG_ON(skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4)); |
1173 | |
1174 | icmp_param.data.icmph = *icmp_hdr(skb); |
1175 | icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY; |
1176 | icmp_param.data.icmph.code = 0; |
1177 | icmp_param.skb = skb; |
1178 | icmp_param.offset = 0; |
1179 | icmp_param.data_len = 0; |
1180 | icmp_param.head_len = sizeof(struct icmphdr) + 12; |
1181 | icmp_reply(icmp_param: &icmp_param, skb); |
1182 | return SKB_NOT_DROPPED_YET; |
1183 | |
1184 | out_err: |
1185 | __ICMP_INC_STATS(dev_net_rcu(skb_dst(skb)->dev), ICMP_MIB_INERRORS); |
1186 | return SKB_DROP_REASON_PKT_TOO_SMALL; |
1187 | } |
1188 | |
1189 | static enum skb_drop_reason icmp_discard(struct sk_buff *skb) |
1190 | { |
1191 | /* pretend it was a success */ |
1192 | return SKB_NOT_DROPPED_YET; |
1193 | } |
1194 | |
1195 | /* |
1196 | * Deal with incoming ICMP packets. |
1197 | */ |
1198 | int icmp_rcv(struct sk_buff *skb) |
1199 | { |
1200 | enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED; |
1201 | struct rtable *rt = skb_rtable(skb); |
1202 | struct net *net = dev_net_rcu(dev: rt->dst.dev); |
1203 | struct icmphdr *icmph; |
1204 | |
1205 | if (!xfrm4_policy_check(NULL, dir: XFRM_POLICY_IN, skb)) { |
1206 | struct sec_path *sp = skb_sec_path(skb); |
1207 | int nh; |
1208 | |
1209 | if (!(sp && sp->xvec[sp->len - 1]->props.flags & |
1210 | XFRM_STATE_ICMP)) { |
1211 | reason = SKB_DROP_REASON_XFRM_POLICY; |
1212 | goto drop; |
1213 | } |
1214 | |
1215 | if (!pskb_may_pull(skb, len: sizeof(*icmph) + sizeof(struct iphdr))) |
1216 | goto drop; |
1217 | |
1218 | nh = skb_network_offset(skb); |
1219 | skb_set_network_header(skb, offset: sizeof(*icmph)); |
1220 | |
1221 | if (!xfrm4_policy_check_reverse(NULL, dir: XFRM_POLICY_IN, |
1222 | skb)) { |
1223 | reason = SKB_DROP_REASON_XFRM_POLICY; |
1224 | goto drop; |
1225 | } |
1226 | |
1227 | skb_set_network_header(skb, offset: nh); |
1228 | } |
1229 | |
1230 | __ICMP_INC_STATS(net, ICMP_MIB_INMSGS); |
1231 | |
1232 | if (skb_checksum_simple_validate(skb)) |
1233 | goto csum_error; |
1234 | |
1235 | if (!pskb_pull(skb, len: sizeof(*icmph))) |
1236 | goto error; |
1237 | |
1238 | icmph = icmp_hdr(skb); |
1239 | |
1240 | ICMPMSGIN_INC_STATS(net, icmph->type); |
1241 | |
1242 | /* Check for ICMP Extended Echo (PROBE) messages */ |
1243 | if (icmph->type == ICMP_EXT_ECHO) { |
1244 | /* We can't use icmp_pointers[].handler() because it is an array of |
1245 | * size NR_ICMP_TYPES + 1 (19 elements) and PROBE has code 42. |
1246 | */ |
1247 | reason = icmp_echo(skb); |
1248 | goto reason_check; |
1249 | } |
1250 | |
1251 | /* |
1252 | * Parse the ICMP message |
1253 | */ |
1254 | |
1255 | if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) { |
1256 | /* |
1257 | * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be |
1258 | * silently ignored (we let user decide with a sysctl). |
1259 | * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently |
1260 | * discarded if to broadcast/multicast. |
1261 | */ |
1262 | if ((icmph->type == ICMP_ECHO || |
1263 | icmph->type == ICMP_TIMESTAMP) && |
1264 | READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_broadcasts)) { |
1265 | reason = SKB_DROP_REASON_INVALID_PROTO; |
1266 | goto error; |
1267 | } |
1268 | if (icmph->type != ICMP_ECHO && |
1269 | icmph->type != ICMP_TIMESTAMP && |
1270 | icmph->type != ICMP_ADDRESS && |
1271 | icmph->type != ICMP_ADDRESSREPLY) { |
1272 | reason = SKB_DROP_REASON_INVALID_PROTO; |
1273 | goto error; |
1274 | } |
1275 | } |
1276 | |
1277 | if (icmph->type == ICMP_EXT_ECHOREPLY || |
1278 | icmph->type == ICMP_ECHOREPLY) { |
1279 | reason = ping_rcv(skb); |
1280 | return reason ? NET_RX_DROP : NET_RX_SUCCESS; |
1281 | } |
1282 | |
1283 | /* |
1284 | * 18 is the highest 'known' ICMP type. Anything else is a mystery |
1285 | * |
1286 | * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently |
1287 | * discarded. |
1288 | */ |
1289 | if (icmph->type > NR_ICMP_TYPES) { |
1290 | reason = SKB_DROP_REASON_UNHANDLED_PROTO; |
1291 | goto error; |
1292 | } |
1293 | |
1294 | reason = icmp_pointers[icmph->type].handler(skb); |
1295 | reason_check: |
1296 | if (!reason) { |
1297 | consume_skb(skb); |
1298 | return NET_RX_SUCCESS; |
1299 | } |
1300 | |
1301 | drop: |
1302 | kfree_skb_reason(skb, reason); |
1303 | return NET_RX_DROP; |
1304 | csum_error: |
1305 | reason = SKB_DROP_REASON_ICMP_CSUM; |
1306 | __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS); |
1307 | error: |
1308 | __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); |
1309 | goto drop; |
1310 | } |
1311 | |
1312 | static bool ip_icmp_error_rfc4884_validate(const struct sk_buff *skb, int off) |
1313 | { |
1314 | struct icmp_extobj_hdr *objh, _objh; |
1315 | struct icmp_ext_hdr *exth, _exth; |
1316 | u16 olen; |
1317 | |
1318 | exth = skb_header_pointer(skb, offset: off, len: sizeof(_exth), buffer: &_exth); |
1319 | if (!exth) |
1320 | return false; |
1321 | if (exth->version != 2) |
1322 | return true; |
1323 | |
1324 | if (exth->checksum && |
1325 | csum_fold(csum: skb_checksum(skb, offset: off, len: skb->len - off, csum: 0))) |
1326 | return false; |
1327 | |
1328 | off += sizeof(_exth); |
1329 | while (off < skb->len) { |
1330 | objh = skb_header_pointer(skb, offset: off, len: sizeof(_objh), buffer: &_objh); |
1331 | if (!objh) |
1332 | return false; |
1333 | |
1334 | olen = ntohs(objh->length); |
1335 | if (olen < sizeof(_objh)) |
1336 | return false; |
1337 | |
1338 | off += olen; |
1339 | if (off > skb->len) |
1340 | return false; |
1341 | } |
1342 | |
1343 | return true; |
1344 | } |
1345 | |
1346 | void ip_icmp_error_rfc4884(const struct sk_buff *skb, |
1347 | struct sock_ee_data_rfc4884 *out, |
1348 | int thlen, int off) |
1349 | { |
1350 | int hlen; |
1351 | |
1352 | /* original datagram headers: end of icmph to payload (skb->data) */ |
1353 | hlen = -skb_transport_offset(skb) - thlen; |
1354 | |
1355 | /* per rfc 4884: minimal datagram length of 128 bytes */ |
1356 | if (off < 128 || off < hlen) |
1357 | return; |
1358 | |
1359 | /* kernel has stripped headers: return payload offset in bytes */ |
1360 | off -= hlen; |
1361 | if (off + sizeof(struct icmp_ext_hdr) > skb->len) |
1362 | return; |
1363 | |
1364 | out->len = off; |
1365 | |
1366 | if (!ip_icmp_error_rfc4884_validate(skb, off)) |
1367 | out->flags |= SO_EE_RFC4884_FLAG_INVALID; |
1368 | } |
1369 | EXPORT_SYMBOL_GPL(ip_icmp_error_rfc4884); |
1370 | |
1371 | int icmp_err(struct sk_buff *skb, u32 info) |
1372 | { |
1373 | struct iphdr *iph = (struct iphdr *)skb->data; |
1374 | int offset = iph->ihl<<2; |
1375 | struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset); |
1376 | struct net *net = dev_net_rcu(dev: skb->dev); |
1377 | int type = icmp_hdr(skb)->type; |
1378 | int code = icmp_hdr(skb)->code; |
1379 | |
1380 | /* |
1381 | * Use ping_err to handle all icmp errors except those |
1382 | * triggered by ICMP_ECHOREPLY which sent from kernel. |
1383 | */ |
1384 | if (icmph->type != ICMP_ECHOREPLY) { |
1385 | ping_err(skb, offset, info); |
1386 | return 0; |
1387 | } |
1388 | |
1389 | if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) |
1390 | ipv4_update_pmtu(skb, net, mtu: info, oif: 0, IPPROTO_ICMP); |
1391 | else if (type == ICMP_REDIRECT) |
1392 | ipv4_redirect(skb, net, oif: 0, IPPROTO_ICMP); |
1393 | |
1394 | return 0; |
1395 | } |
1396 | |
1397 | /* |
1398 | * This table is the definition of how we handle ICMP. |
1399 | */ |
1400 | static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = { |
1401 | [ICMP_ECHOREPLY] = { |
1402 | .handler = ping_rcv, |
1403 | }, |
1404 | [1] = { |
1405 | .handler = icmp_discard, |
1406 | .error = 1, |
1407 | }, |
1408 | [2] = { |
1409 | .handler = icmp_discard, |
1410 | .error = 1, |
1411 | }, |
1412 | [ICMP_DEST_UNREACH] = { |
1413 | .handler = icmp_unreach, |
1414 | .error = 1, |
1415 | }, |
1416 | [ICMP_SOURCE_QUENCH] = { |
1417 | .handler = icmp_unreach, |
1418 | .error = 1, |
1419 | }, |
1420 | [ICMP_REDIRECT] = { |
1421 | .handler = icmp_redirect, |
1422 | .error = 1, |
1423 | }, |
1424 | [6] = { |
1425 | .handler = icmp_discard, |
1426 | .error = 1, |
1427 | }, |
1428 | [7] = { |
1429 | .handler = icmp_discard, |
1430 | .error = 1, |
1431 | }, |
1432 | [ICMP_ECHO] = { |
1433 | .handler = icmp_echo, |
1434 | }, |
1435 | [9] = { |
1436 | .handler = icmp_discard, |
1437 | .error = 1, |
1438 | }, |
1439 | [10] = { |
1440 | .handler = icmp_discard, |
1441 | .error = 1, |
1442 | }, |
1443 | [ICMP_TIME_EXCEEDED] = { |
1444 | .handler = icmp_unreach, |
1445 | .error = 1, |
1446 | }, |
1447 | [ICMP_PARAMETERPROB] = { |
1448 | .handler = icmp_unreach, |
1449 | .error = 1, |
1450 | }, |
1451 | [ICMP_TIMESTAMP] = { |
1452 | .handler = icmp_timestamp, |
1453 | }, |
1454 | [ICMP_TIMESTAMPREPLY] = { |
1455 | .handler = icmp_discard, |
1456 | }, |
1457 | [ICMP_INFO_REQUEST] = { |
1458 | .handler = icmp_discard, |
1459 | }, |
1460 | [ICMP_INFO_REPLY] = { |
1461 | .handler = icmp_discard, |
1462 | }, |
1463 | [ICMP_ADDRESS] = { |
1464 | .handler = icmp_discard, |
1465 | }, |
1466 | [ICMP_ADDRESSREPLY] = { |
1467 | .handler = icmp_discard, |
1468 | }, |
1469 | }; |
1470 | |
1471 | static int __net_init icmp_sk_init(struct net *net) |
1472 | { |
1473 | /* Control parameters for ECHO replies. */ |
1474 | net->ipv4.sysctl_icmp_echo_ignore_all = 0; |
1475 | net->ipv4.sysctl_icmp_echo_enable_probe = 0; |
1476 | net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1; |
1477 | |
1478 | /* Control parameter - ignore bogus broadcast responses? */ |
1479 | net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1; |
1480 | |
1481 | /* |
1482 | * Configurable global rate limit. |
1483 | * |
1484 | * ratelimit defines tokens/packet consumed for dst->rate_token |
1485 | * bucket ratemask defines which icmp types are ratelimited by |
1486 | * setting it's bit position. |
1487 | * |
1488 | * default: |
1489 | * dest unreachable (3), source quench (4), |
1490 | * time exceeded (11), parameter problem (12) |
1491 | */ |
1492 | |
1493 | net->ipv4.sysctl_icmp_ratelimit = 1 * HZ; |
1494 | net->ipv4.sysctl_icmp_ratemask = 0x1818; |
1495 | net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0; |
1496 | net->ipv4.sysctl_icmp_msgs_per_sec = 1000; |
1497 | net->ipv4.sysctl_icmp_msgs_burst = 50; |
1498 | |
1499 | return 0; |
1500 | } |
1501 | |
1502 | static struct pernet_operations __net_initdata icmp_sk_ops = { |
1503 | .init = icmp_sk_init, |
1504 | }; |
1505 | |
1506 | int __init icmp_init(void) |
1507 | { |
1508 | int err, i; |
1509 | |
1510 | for_each_possible_cpu(i) { |
1511 | struct sock *sk; |
1512 | |
1513 | err = inet_ctl_sock_create(sk: &sk, PF_INET, |
1514 | type: SOCK_RAW, IPPROTO_ICMP, net: &init_net); |
1515 | if (err < 0) |
1516 | return err; |
1517 | |
1518 | per_cpu(ipv4_icmp_sk, i) = sk; |
1519 | |
1520 | /* Enough space for 2 64K ICMP packets, including |
1521 | * sk_buff/skb_shared_info struct overhead. |
1522 | */ |
1523 | sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024); |
1524 | |
1525 | /* |
1526 | * Speedup sock_wfree() |
1527 | */ |
1528 | sock_set_flag(sk, flag: SOCK_USE_WRITE_QUEUE); |
1529 | inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT; |
1530 | } |
1531 | return register_pernet_subsys(&icmp_sk_ops); |
1532 | } |
1533 |
Definitions
- icmp_bxm
- icmp_err_convert
- icmp_control
- icmp_pointers
- ipv4_icmp_sk
- icmp_xmit_lock
- icmp_xmit_unlock
- icmp_global_allow
- icmp_global_consume
- icmpv4_mask_allow
- icmpv4_global_allow
- icmpv4_xrlim_allow
- icmp_out_count
- icmp_glue_bits
- icmp_push_reply
- icmp_reply
- icmp_get_route_lookup_dev
- icmp_route_lookup
- __icmp_send
- icmp_ndo_send
- icmp_socket_deliver
- icmp_tag_validation
- icmp_unreach
- icmp_redirect
- icmp_echo
- icmp_build_probe
- icmp_timestamp
- icmp_discard
- icmp_rcv
- ip_icmp_error_rfc4884_validate
- ip_icmp_error_rfc4884
- icmp_err
- icmp_pointers
- icmp_sk_init
- icmp_sk_ops
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