1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Internet Control Message Protocol (ICMPv6)
4 * Linux INET6 implementation
5 *
6 * Authors:
7 * Pedro Roque <roque@di.fc.ul.pt>
8 *
9 * Based on net/ipv4/icmp.c
10 *
11 * RFC 1885
12 */
13
14 /*
15 * Changes:
16 *
17 * Andi Kleen : exception handling
18 * Andi Kleen add rate limits. never reply to a icmp.
19 * add more length checks and other fixes.
20 * yoshfuji : ensure to sent parameter problem for
21 * fragments.
22 * YOSHIFUJI Hideaki @USAGI: added sysctl for icmp rate limit.
23 * Randy Dunlap and
24 * YOSHIFUJI Hideaki @USAGI: Per-interface statistics support
25 * Kazunori MIYAZAWA @USAGI: change output process to use ip6_append_data
26 */
27
28 #define pr_fmt(fmt) "IPv6: " fmt
29
30 #include <linux/module.h>
31 #include <linux/errno.h>
32 #include <linux/types.h>
33 #include <linux/socket.h>
34 #include <linux/in.h>
35 #include <linux/kernel.h>
36 #include <linux/sockios.h>
37 #include <linux/net.h>
38 #include <linux/skbuff.h>
39 #include <linux/init.h>
40 #include <linux/netfilter.h>
41 #include <linux/slab.h>
42
43 #ifdef CONFIG_SYSCTL
44 #include <linux/sysctl.h>
45 #endif
46
47 #include <linux/inet.h>
48 #include <linux/netdevice.h>
49 #include <linux/icmpv6.h>
50
51 #include <net/ip.h>
52 #include <net/sock.h>
53
54 #include <net/ipv6.h>
55 #include <net/ip6_checksum.h>
56 #include <net/ping.h>
57 #include <net/protocol.h>
58 #include <net/raw.h>
59 #include <net/rawv6.h>
60 #include <net/seg6.h>
61 #include <net/transp_v6.h>
62 #include <net/ip6_route.h>
63 #include <net/addrconf.h>
64 #include <net/icmp.h>
65 #include <net/xfrm.h>
66 #include <net/inet_common.h>
67 #include <net/dsfield.h>
68 #include <net/l3mdev.h>
69
70 #include <linux/uaccess.h>
71
72 static DEFINE_PER_CPU(struct sock *, ipv6_icmp_sk);
73
icmpv6_err(struct sk_buff * skb,struct inet6_skb_parm * opt,u8 type,u8 code,int offset,__be32 info)74 static int icmpv6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
75 u8 type, u8 code, int offset, __be32 info)
76 {
77 /* icmpv6_notify checks 8 bytes can be pulled, icmp6hdr is 8 bytes */
78 struct icmp6hdr *icmp6 = (struct icmp6hdr *) (skb->data + offset);
79 struct net *net = dev_net(skb->dev);
80
81 if (type == ICMPV6_PKT_TOOBIG)
82 ip6_update_pmtu(skb, net, info, skb->dev->ifindex, 0, sock_net_uid(net, NULL));
83 else if (type == NDISC_REDIRECT)
84 ip6_redirect(skb, net, skb->dev->ifindex, 0,
85 sock_net_uid(net, NULL));
86
87 if (!(type & ICMPV6_INFOMSG_MASK))
88 if (icmp6->icmp6_type == ICMPV6_ECHO_REQUEST)
89 ping_err(skb, offset, ntohl(info));
90
91 return 0;
92 }
93
94 static int icmpv6_rcv(struct sk_buff *skb);
95
96 static const struct inet6_protocol icmpv6_protocol = {
97 .handler = icmpv6_rcv,
98 .err_handler = icmpv6_err,
99 .flags = INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,
100 };
101
102 /* Called with BH disabled */
icmpv6_xmit_lock(struct net * net)103 static struct sock *icmpv6_xmit_lock(struct net *net)
104 {
105 struct sock *sk;
106
107 sk = this_cpu_read(ipv6_icmp_sk);
108 if (unlikely(!spin_trylock(&sk->sk_lock.slock))) {
109 /* This can happen if the output path (f.e. SIT or
110 * ip6ip6 tunnel) signals dst_link_failure() for an
111 * outgoing ICMP6 packet.
112 */
113 return NULL;
114 }
115 sock_net_set(sk, net);
116 return sk;
117 }
118
icmpv6_xmit_unlock(struct sock * sk)119 static void icmpv6_xmit_unlock(struct sock *sk)
120 {
121 sock_net_set(sk, &init_net);
122 spin_unlock(&sk->sk_lock.slock);
123 }
124
125 /*
126 * Figure out, may we reply to this packet with icmp error.
127 *
128 * We do not reply, if:
129 * - it was icmp error message.
130 * - it is truncated, so that it is known, that protocol is ICMPV6
131 * (i.e. in the middle of some exthdr)
132 *
133 * --ANK (980726)
134 */
135
is_ineligible(const struct sk_buff * skb)136 static bool is_ineligible(const struct sk_buff *skb)
137 {
138 int ptr = (u8 *)(ipv6_hdr(skb) + 1) - skb->data;
139 int len = skb->len - ptr;
140 __u8 nexthdr = ipv6_hdr(skb)->nexthdr;
141 __be16 frag_off;
142
143 if (len < 0)
144 return true;
145
146 ptr = ipv6_skip_exthdr(skb, ptr, &nexthdr, &frag_off);
147 if (ptr < 0)
148 return false;
149 if (nexthdr == IPPROTO_ICMPV6) {
150 u8 _type, *tp;
151 tp = skb_header_pointer(skb,
152 ptr+offsetof(struct icmp6hdr, icmp6_type),
153 sizeof(_type), &_type);
154
155 /* Based on RFC 8200, Section 4.5 Fragment Header, return
156 * false if this is a fragment packet with no icmp header info.
157 */
158 if (!tp && frag_off != 0)
159 return false;
160 else if (!tp || !(*tp & ICMPV6_INFOMSG_MASK))
161 return true;
162 }
163 return false;
164 }
165
icmpv6_mask_allow(struct net * net,int type)166 static bool icmpv6_mask_allow(struct net *net, int type)
167 {
168 if (type > ICMPV6_MSG_MAX)
169 return true;
170
171 /* Limit if icmp type is set in ratemask. */
172 if (!test_bit(type, net->ipv6.sysctl.icmpv6_ratemask))
173 return true;
174
175 return false;
176 }
177
icmpv6_global_allow(struct net * net,int type)178 static bool icmpv6_global_allow(struct net *net, int type)
179 {
180 if (icmpv6_mask_allow(net, type))
181 return true;
182
183 if (icmp_global_allow())
184 return true;
185
186 __ICMP_INC_STATS(net, ICMP_MIB_RATELIMITGLOBAL);
187 return false;
188 }
189
190 /*
191 * Check the ICMP output rate limit
192 */
icmpv6_xrlim_allow(struct sock * sk,u8 type,struct flowi6 * fl6)193 static bool icmpv6_xrlim_allow(struct sock *sk, u8 type,
194 struct flowi6 *fl6)
195 {
196 struct net *net = sock_net(sk);
197 struct dst_entry *dst;
198 bool res = false;
199
200 if (icmpv6_mask_allow(net, type))
201 return true;
202
203 /*
204 * Look up the output route.
205 * XXX: perhaps the expire for routing entries cloned by
206 * this lookup should be more aggressive (not longer than timeout).
207 */
208 dst = ip6_route_output(net, sk, fl6);
209 if (dst->error) {
210 IP6_INC_STATS(net, ip6_dst_idev(dst),
211 IPSTATS_MIB_OUTNOROUTES);
212 } else if (dst->dev && (dst->dev->flags&IFF_LOOPBACK)) {
213 res = true;
214 } else {
215 struct rt6_info *rt = (struct rt6_info *)dst;
216 int tmo = net->ipv6.sysctl.icmpv6_time;
217 struct inet_peer *peer;
218
219 /* Give more bandwidth to wider prefixes. */
220 if (rt->rt6i_dst.plen < 128)
221 tmo >>= ((128 - rt->rt6i_dst.plen)>>5);
222
223 peer = inet_getpeer_v6(net->ipv6.peers, &fl6->daddr, 1);
224 res = inet_peer_xrlim_allow(peer, tmo);
225 if (peer)
226 inet_putpeer(peer);
227 }
228 if (!res)
229 __ICMP6_INC_STATS(net, ip6_dst_idev(dst),
230 ICMP6_MIB_RATELIMITHOST);
231 dst_release(dst);
232 return res;
233 }
234
icmpv6_rt_has_prefsrc(struct sock * sk,u8 type,struct flowi6 * fl6)235 static bool icmpv6_rt_has_prefsrc(struct sock *sk, u8 type,
236 struct flowi6 *fl6)
237 {
238 struct net *net = sock_net(sk);
239 struct dst_entry *dst;
240 bool res = false;
241
242 dst = ip6_route_output(net, sk, fl6);
243 if (!dst->error) {
244 struct rt6_info *rt = (struct rt6_info *)dst;
245 struct in6_addr prefsrc;
246
247 rt6_get_prefsrc(rt, &prefsrc);
248 res = !ipv6_addr_any(&prefsrc);
249 }
250 dst_release(dst);
251 return res;
252 }
253
254 /*
255 * an inline helper for the "simple" if statement below
256 * checks if parameter problem report is caused by an
257 * unrecognized IPv6 option that has the Option Type
258 * highest-order two bits set to 10
259 */
260
opt_unrec(struct sk_buff * skb,__u32 offset)261 static bool opt_unrec(struct sk_buff *skb, __u32 offset)
262 {
263 u8 _optval, *op;
264
265 offset += skb_network_offset(skb);
266 op = skb_header_pointer(skb, offset, sizeof(_optval), &_optval);
267 if (!op)
268 return true;
269 return (*op & 0xC0) == 0x80;
270 }
271
icmpv6_push_pending_frames(struct sock * sk,struct flowi6 * fl6,struct icmp6hdr * thdr,int len)272 void icmpv6_push_pending_frames(struct sock *sk, struct flowi6 *fl6,
273 struct icmp6hdr *thdr, int len)
274 {
275 struct sk_buff *skb;
276 struct icmp6hdr *icmp6h;
277
278 skb = skb_peek(&sk->sk_write_queue);
279 if (!skb)
280 return;
281
282 icmp6h = icmp6_hdr(skb);
283 memcpy(icmp6h, thdr, sizeof(struct icmp6hdr));
284 icmp6h->icmp6_cksum = 0;
285
286 if (skb_queue_len(&sk->sk_write_queue) == 1) {
287 skb->csum = csum_partial(icmp6h,
288 sizeof(struct icmp6hdr), skb->csum);
289 icmp6h->icmp6_cksum = csum_ipv6_magic(&fl6->saddr,
290 &fl6->daddr,
291 len, fl6->flowi6_proto,
292 skb->csum);
293 } else {
294 __wsum tmp_csum = 0;
295
296 skb_queue_walk(&sk->sk_write_queue, skb) {
297 tmp_csum = csum_add(tmp_csum, skb->csum);
298 }
299
300 tmp_csum = csum_partial(icmp6h,
301 sizeof(struct icmp6hdr), tmp_csum);
302 icmp6h->icmp6_cksum = csum_ipv6_magic(&fl6->saddr,
303 &fl6->daddr,
304 len, fl6->flowi6_proto,
305 tmp_csum);
306 }
307 ip6_push_pending_frames(sk);
308 }
309
310 struct icmpv6_msg {
311 struct sk_buff *skb;
312 int offset;
313 uint8_t type;
314 };
315
icmpv6_getfrag(void * from,char * to,int offset,int len,int odd,struct sk_buff * skb)316 static int icmpv6_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
317 {
318 struct icmpv6_msg *msg = (struct icmpv6_msg *) from;
319 struct sk_buff *org_skb = msg->skb;
320 __wsum csum;
321
322 csum = skb_copy_and_csum_bits(org_skb, msg->offset + offset,
323 to, len);
324 skb->csum = csum_block_add(skb->csum, csum, odd);
325 if (!(msg->type & ICMPV6_INFOMSG_MASK))
326 nf_ct_attach(skb, org_skb);
327 return 0;
328 }
329
330 #if IS_ENABLED(CONFIG_IPV6_MIP6)
mip6_addr_swap(struct sk_buff * skb,const struct inet6_skb_parm * opt)331 static void mip6_addr_swap(struct sk_buff *skb, const struct inet6_skb_parm *opt)
332 {
333 struct ipv6hdr *iph = ipv6_hdr(skb);
334 struct ipv6_destopt_hao *hao;
335 int off;
336
337 if (opt->dsthao) {
338 off = ipv6_find_tlv(skb, opt->dsthao, IPV6_TLV_HAO);
339 if (likely(off >= 0)) {
340 hao = (struct ipv6_destopt_hao *)
341 (skb_network_header(skb) + off);
342 swap(iph->saddr, hao->addr);
343 }
344 }
345 }
346 #else
mip6_addr_swap(struct sk_buff * skb,const struct inet6_skb_parm * opt)347 static inline void mip6_addr_swap(struct sk_buff *skb, const struct inet6_skb_parm *opt) {}
348 #endif
349
icmpv6_route_lookup(struct net * net,struct sk_buff * skb,struct sock * sk,struct flowi6 * fl6)350 static struct dst_entry *icmpv6_route_lookup(struct net *net,
351 struct sk_buff *skb,
352 struct sock *sk,
353 struct flowi6 *fl6)
354 {
355 struct dst_entry *dst, *dst2;
356 struct flowi6 fl2;
357 int err;
358
359 err = ip6_dst_lookup(net, sk, &dst, fl6);
360 if (err)
361 return ERR_PTR(err);
362
363 /*
364 * We won't send icmp if the destination is known
365 * anycast unless we need to treat anycast as unicast.
366 */
367 if (!READ_ONCE(net->ipv6.sysctl.icmpv6_error_anycast_as_unicast) &&
368 ipv6_anycast_destination(dst, &fl6->daddr)) {
369 net_dbg_ratelimited("icmp6_send: acast source\n");
370 dst_release(dst);
371 return ERR_PTR(-EINVAL);
372 }
373
374 /* No need to clone since we're just using its address. */
375 dst2 = dst;
376
377 dst = xfrm_lookup(net, dst, flowi6_to_flowi(fl6), sk, 0);
378 if (!IS_ERR(dst)) {
379 if (dst != dst2)
380 return dst;
381 } else {
382 if (PTR_ERR(dst) == -EPERM)
383 dst = NULL;
384 else
385 return dst;
386 }
387
388 err = xfrm_decode_session_reverse(skb, flowi6_to_flowi(&fl2), AF_INET6);
389 if (err)
390 goto relookup_failed;
391
392 err = ip6_dst_lookup(net, sk, &dst2, &fl2);
393 if (err)
394 goto relookup_failed;
395
396 dst2 = xfrm_lookup(net, dst2, flowi6_to_flowi(&fl2), sk, XFRM_LOOKUP_ICMP);
397 if (!IS_ERR(dst2)) {
398 dst_release(dst);
399 dst = dst2;
400 } else {
401 err = PTR_ERR(dst2);
402 if (err == -EPERM) {
403 dst_release(dst);
404 return dst2;
405 } else
406 goto relookup_failed;
407 }
408
409 relookup_failed:
410 if (dst)
411 return dst;
412 return ERR_PTR(err);
413 }
414
icmp6_dev(const struct sk_buff * skb)415 static struct net_device *icmp6_dev(const struct sk_buff *skb)
416 {
417 struct net_device *dev = skb->dev;
418
419 /* for local traffic to local address, skb dev is the loopback
420 * device. Check if there is a dst attached to the skb and if so
421 * get the real device index. Same is needed for replies to a link
422 * local address on a device enslaved to an L3 master device
423 */
424 if (unlikely(dev->ifindex == LOOPBACK_IFINDEX || netif_is_l3_master(skb->dev))) {
425 const struct rt6_info *rt6 = skb_rt6_info(skb);
426
427 /* The destination could be an external IP in Ext Hdr (SRv6, RPL, etc.),
428 * and ip6_null_entry could be set to skb if no route is found.
429 */
430 if (rt6 && rt6->rt6i_idev)
431 dev = rt6->rt6i_idev->dev;
432 }
433
434 return dev;
435 }
436
icmp6_iif(const struct sk_buff * skb)437 static int icmp6_iif(const struct sk_buff *skb)
438 {
439 return icmp6_dev(skb)->ifindex;
440 }
441
442 /*
443 * Send an ICMP message in response to a packet in error
444 */
icmp6_send(struct sk_buff * skb,u8 type,u8 code,__u32 info,const struct in6_addr * force_saddr,const struct inet6_skb_parm * parm)445 void icmp6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info,
446 const struct in6_addr *force_saddr,
447 const struct inet6_skb_parm *parm)
448 {
449 struct inet6_dev *idev = NULL;
450 struct ipv6hdr *hdr = ipv6_hdr(skb);
451 struct sock *sk;
452 struct net *net;
453 struct ipv6_pinfo *np;
454 const struct in6_addr *saddr = NULL;
455 struct dst_entry *dst;
456 struct icmp6hdr tmp_hdr;
457 struct flowi6 fl6;
458 struct icmpv6_msg msg;
459 struct ipcm6_cookie ipc6;
460 int iif = 0;
461 int addr_type = 0;
462 int len;
463 u32 mark;
464
465 if ((u8 *)hdr < skb->head ||
466 (skb_network_header(skb) + sizeof(*hdr)) > skb_tail_pointer(skb))
467 return;
468
469 if (!skb->dev)
470 return;
471 net = dev_net(skb->dev);
472 mark = IP6_REPLY_MARK(net, skb->mark);
473 /*
474 * Make sure we respect the rules
475 * i.e. RFC 1885 2.4(e)
476 * Rule (e.1) is enforced by not using icmp6_send
477 * in any code that processes icmp errors.
478 */
479 addr_type = ipv6_addr_type(&hdr->daddr);
480
481 if (ipv6_chk_addr(net, &hdr->daddr, skb->dev, 0) ||
482 ipv6_chk_acast_addr_src(net, skb->dev, &hdr->daddr))
483 saddr = &hdr->daddr;
484
485 /*
486 * Dest addr check
487 */
488
489 if (addr_type & IPV6_ADDR_MULTICAST || skb->pkt_type != PACKET_HOST) {
490 if (type != ICMPV6_PKT_TOOBIG &&
491 !(type == ICMPV6_PARAMPROB &&
492 code == ICMPV6_UNK_OPTION &&
493 (opt_unrec(skb, info))))
494 return;
495
496 saddr = NULL;
497 }
498
499 addr_type = ipv6_addr_type(&hdr->saddr);
500
501 /*
502 * Source addr check
503 */
504
505 if (__ipv6_addr_needs_scope_id(addr_type)) {
506 iif = icmp6_iif(skb);
507 } else {
508 /*
509 * The source device is used for looking up which routing table
510 * to use for sending an ICMP error.
511 */
512 iif = l3mdev_master_ifindex(skb->dev);
513 }
514
515 /*
516 * Must not send error if the source does not uniquely
517 * identify a single node (RFC2463 Section 2.4).
518 * We check unspecified / multicast addresses here,
519 * and anycast addresses will be checked later.
520 */
521 if ((addr_type == IPV6_ADDR_ANY) || (addr_type & IPV6_ADDR_MULTICAST)) {
522 net_dbg_ratelimited("icmp6_send: addr_any/mcast source [%pI6c > %pI6c]\n",
523 &hdr->saddr, &hdr->daddr);
524 return;
525 }
526
527 /*
528 * Never answer to a ICMP packet.
529 */
530 if (is_ineligible(skb)) {
531 net_dbg_ratelimited("icmp6_send: no reply to icmp error [%pI6c > %pI6c]\n",
532 &hdr->saddr, &hdr->daddr);
533 return;
534 }
535
536 /* Needed by both icmp_global_allow and icmpv6_xmit_lock */
537 local_bh_disable();
538
539 /* Check global sysctl_icmp_msgs_per_sec ratelimit */
540 if (!(skb->dev->flags & IFF_LOOPBACK) && !icmpv6_global_allow(net, type))
541 goto out_bh_enable;
542
543 mip6_addr_swap(skb, parm);
544
545 sk = icmpv6_xmit_lock(net);
546 if (!sk)
547 goto out_bh_enable;
548
549 memset(&fl6, 0, sizeof(fl6));
550 fl6.flowi6_proto = IPPROTO_ICMPV6;
551 fl6.daddr = hdr->saddr;
552 if (force_saddr)
553 saddr = force_saddr;
554 if (saddr) {
555 fl6.saddr = *saddr;
556 } else if (!icmpv6_rt_has_prefsrc(sk, type, &fl6)) {
557 /* select a more meaningful saddr from input if */
558 struct net_device *in_netdev;
559
560 in_netdev = dev_get_by_index(net, parm->iif);
561 if (in_netdev) {
562 ipv6_dev_get_saddr(net, in_netdev, &fl6.daddr,
563 inet6_sk(sk)->srcprefs,
564 &fl6.saddr);
565 dev_put(in_netdev);
566 }
567 }
568 fl6.flowi6_mark = mark;
569 fl6.flowi6_oif = iif;
570 fl6.fl6_icmp_type = type;
571 fl6.fl6_icmp_code = code;
572 fl6.flowi6_uid = sock_net_uid(net, NULL);
573 fl6.mp_hash = rt6_multipath_hash(net, &fl6, skb, NULL);
574 security_skb_classify_flow(skb, flowi6_to_flowi_common(&fl6));
575
576 np = inet6_sk(sk);
577
578 if (!icmpv6_xrlim_allow(sk, type, &fl6))
579 goto out;
580
581 tmp_hdr.icmp6_type = type;
582 tmp_hdr.icmp6_code = code;
583 tmp_hdr.icmp6_cksum = 0;
584 tmp_hdr.icmp6_pointer = htonl(info);
585
586 if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
587 fl6.flowi6_oif = np->mcast_oif;
588 else if (!fl6.flowi6_oif)
589 fl6.flowi6_oif = np->ucast_oif;
590
591 ipcm6_init_sk(&ipc6, np);
592 ipc6.sockc.mark = mark;
593 fl6.flowlabel = ip6_make_flowinfo(ipc6.tclass, fl6.flowlabel);
594
595 dst = icmpv6_route_lookup(net, skb, sk, &fl6);
596 if (IS_ERR(dst))
597 goto out;
598
599 ipc6.hlimit = ip6_sk_dst_hoplimit(np, &fl6, dst);
600
601 msg.skb = skb;
602 msg.offset = skb_network_offset(skb);
603 msg.type = type;
604
605 len = skb->len - msg.offset;
606 len = min_t(unsigned int, len, IPV6_MIN_MTU - sizeof(struct ipv6hdr) - sizeof(struct icmp6hdr));
607 if (len < 0) {
608 net_dbg_ratelimited("icmp: len problem [%pI6c > %pI6c]\n",
609 &hdr->saddr, &hdr->daddr);
610 goto out_dst_release;
611 }
612
613 rcu_read_lock();
614 idev = __in6_dev_get(skb->dev);
615
616 if (ip6_append_data(sk, icmpv6_getfrag, &msg,
617 len + sizeof(struct icmp6hdr),
618 sizeof(struct icmp6hdr),
619 &ipc6, &fl6, (struct rt6_info *)dst,
620 MSG_DONTWAIT)) {
621 ICMP6_INC_STATS(net, idev, ICMP6_MIB_OUTERRORS);
622 ip6_flush_pending_frames(sk);
623 } else {
624 icmpv6_push_pending_frames(sk, &fl6, &tmp_hdr,
625 len + sizeof(struct icmp6hdr));
626 }
627 rcu_read_unlock();
628 out_dst_release:
629 dst_release(dst);
630 out:
631 icmpv6_xmit_unlock(sk);
632 out_bh_enable:
633 local_bh_enable();
634 }
635 EXPORT_SYMBOL(icmp6_send);
636
637 /* Slightly more convenient version of icmp6_send with drop reasons.
638 */
icmpv6_param_prob_reason(struct sk_buff * skb,u8 code,int pos,enum skb_drop_reason reason)639 void icmpv6_param_prob_reason(struct sk_buff *skb, u8 code, int pos,
640 enum skb_drop_reason reason)
641 {
642 icmp6_send(skb, ICMPV6_PARAMPROB, code, pos, NULL, IP6CB(skb));
643 kfree_skb_reason(skb, reason);
644 }
645
646 /* Generate icmpv6 with type/code ICMPV6_DEST_UNREACH/ICMPV6_ADDR_UNREACH
647 * if sufficient data bytes are available
648 * @nhs is the size of the tunnel header(s) :
649 * Either an IPv4 header for SIT encap
650 * an IPv4 header + GRE header for GRE encap
651 */
ip6_err_gen_icmpv6_unreach(struct sk_buff * skb,int nhs,int type,unsigned int data_len)652 int ip6_err_gen_icmpv6_unreach(struct sk_buff *skb, int nhs, int type,
653 unsigned int data_len)
654 {
655 struct in6_addr temp_saddr;
656 struct rt6_info *rt;
657 struct sk_buff *skb2;
658 u32 info = 0;
659
660 if (!pskb_may_pull(skb, nhs + sizeof(struct ipv6hdr) + 8))
661 return 1;
662
663 /* RFC 4884 (partial) support for ICMP extensions */
664 if (data_len < 128 || (data_len & 7) || skb->len < data_len)
665 data_len = 0;
666
667 skb2 = data_len ? skb_copy(skb, GFP_ATOMIC) : skb_clone(skb, GFP_ATOMIC);
668
669 if (!skb2)
670 return 1;
671
672 skb_dst_drop(skb2);
673 skb_pull(skb2, nhs);
674 skb_reset_network_header(skb2);
675
676 rt = rt6_lookup(dev_net(skb->dev), &ipv6_hdr(skb2)->saddr, NULL, 0,
677 skb, 0);
678
679 if (rt && rt->dst.dev)
680 skb2->dev = rt->dst.dev;
681
682 ipv6_addr_set_v4mapped(ip_hdr(skb)->saddr, &temp_saddr);
683
684 if (data_len) {
685 /* RFC 4884 (partial) support :
686 * insert 0 padding at the end, before the extensions
687 */
688 __skb_push(skb2, nhs);
689 skb_reset_network_header(skb2);
690 memmove(skb2->data, skb2->data + nhs, data_len - nhs);
691 memset(skb2->data + data_len - nhs, 0, nhs);
692 /* RFC 4884 4.5 : Length is measured in 64-bit words,
693 * and stored in reserved[0]
694 */
695 info = (data_len/8) << 24;
696 }
697 if (type == ICMP_TIME_EXCEEDED)
698 icmp6_send(skb2, ICMPV6_TIME_EXCEED, ICMPV6_EXC_HOPLIMIT,
699 info, &temp_saddr, IP6CB(skb2));
700 else
701 icmp6_send(skb2, ICMPV6_DEST_UNREACH, ICMPV6_ADDR_UNREACH,
702 info, &temp_saddr, IP6CB(skb2));
703 if (rt)
704 ip6_rt_put(rt);
705
706 kfree_skb(skb2);
707
708 return 0;
709 }
710 EXPORT_SYMBOL(ip6_err_gen_icmpv6_unreach);
711
icmpv6_echo_reply(struct sk_buff * skb)712 static enum skb_drop_reason icmpv6_echo_reply(struct sk_buff *skb)
713 {
714 struct net *net = dev_net(skb->dev);
715 struct sock *sk;
716 struct inet6_dev *idev;
717 struct ipv6_pinfo *np;
718 const struct in6_addr *saddr = NULL;
719 struct icmp6hdr *icmph = icmp6_hdr(skb);
720 struct icmp6hdr tmp_hdr;
721 struct flowi6 fl6;
722 struct icmpv6_msg msg;
723 struct dst_entry *dst;
724 struct ipcm6_cookie ipc6;
725 u32 mark = IP6_REPLY_MARK(net, skb->mark);
726 SKB_DR(reason);
727 bool acast;
728 u8 type;
729
730 if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr) &&
731 net->ipv6.sysctl.icmpv6_echo_ignore_multicast)
732 return reason;
733
734 saddr = &ipv6_hdr(skb)->daddr;
735
736 acast = ipv6_anycast_destination(skb_dst(skb), saddr);
737 if (acast && net->ipv6.sysctl.icmpv6_echo_ignore_anycast)
738 return reason;
739
740 if (!ipv6_unicast_destination(skb) &&
741 !(net->ipv6.sysctl.anycast_src_echo_reply && acast))
742 saddr = NULL;
743
744 if (icmph->icmp6_type == ICMPV6_EXT_ECHO_REQUEST)
745 type = ICMPV6_EXT_ECHO_REPLY;
746 else
747 type = ICMPV6_ECHO_REPLY;
748
749 memcpy(&tmp_hdr, icmph, sizeof(tmp_hdr));
750 tmp_hdr.icmp6_type = type;
751
752 memset(&fl6, 0, sizeof(fl6));
753 if (net->ipv6.sysctl.flowlabel_reflect & FLOWLABEL_REFLECT_ICMPV6_ECHO_REPLIES)
754 fl6.flowlabel = ip6_flowlabel(ipv6_hdr(skb));
755
756 fl6.flowi6_proto = IPPROTO_ICMPV6;
757 fl6.daddr = ipv6_hdr(skb)->saddr;
758 if (saddr)
759 fl6.saddr = *saddr;
760 fl6.flowi6_oif = icmp6_iif(skb);
761 fl6.fl6_icmp_type = type;
762 fl6.flowi6_mark = mark;
763 fl6.flowi6_uid = sock_net_uid(net, NULL);
764 security_skb_classify_flow(skb, flowi6_to_flowi_common(&fl6));
765
766 local_bh_disable();
767 sk = icmpv6_xmit_lock(net);
768 if (!sk)
769 goto out_bh_enable;
770 np = inet6_sk(sk);
771
772 if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
773 fl6.flowi6_oif = np->mcast_oif;
774 else if (!fl6.flowi6_oif)
775 fl6.flowi6_oif = np->ucast_oif;
776
777 if (ip6_dst_lookup(net, sk, &dst, &fl6))
778 goto out;
779 dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), sk, 0);
780 if (IS_ERR(dst))
781 goto out;
782
783 /* Check the ratelimit */
784 if ((!(skb->dev->flags & IFF_LOOPBACK) && !icmpv6_global_allow(net, ICMPV6_ECHO_REPLY)) ||
785 !icmpv6_xrlim_allow(sk, ICMPV6_ECHO_REPLY, &fl6))
786 goto out_dst_release;
787
788 idev = __in6_dev_get(skb->dev);
789
790 msg.skb = skb;
791 msg.offset = 0;
792 msg.type = type;
793
794 ipcm6_init_sk(&ipc6, np);
795 ipc6.hlimit = ip6_sk_dst_hoplimit(np, &fl6, dst);
796 ipc6.tclass = ipv6_get_dsfield(ipv6_hdr(skb));
797 ipc6.sockc.mark = mark;
798
799 if (icmph->icmp6_type == ICMPV6_EXT_ECHO_REQUEST)
800 if (!icmp_build_probe(skb, (struct icmphdr *)&tmp_hdr))
801 goto out_dst_release;
802
803 if (ip6_append_data(sk, icmpv6_getfrag, &msg,
804 skb->len + sizeof(struct icmp6hdr),
805 sizeof(struct icmp6hdr), &ipc6, &fl6,
806 (struct rt6_info *)dst, MSG_DONTWAIT)) {
807 __ICMP6_INC_STATS(net, idev, ICMP6_MIB_OUTERRORS);
808 ip6_flush_pending_frames(sk);
809 } else {
810 icmpv6_push_pending_frames(sk, &fl6, &tmp_hdr,
811 skb->len + sizeof(struct icmp6hdr));
812 reason = SKB_CONSUMED;
813 }
814 out_dst_release:
815 dst_release(dst);
816 out:
817 icmpv6_xmit_unlock(sk);
818 out_bh_enable:
819 local_bh_enable();
820 return reason;
821 }
822
icmpv6_notify(struct sk_buff * skb,u8 type,u8 code,__be32 info)823 enum skb_drop_reason icmpv6_notify(struct sk_buff *skb, u8 type,
824 u8 code, __be32 info)
825 {
826 struct inet6_skb_parm *opt = IP6CB(skb);
827 struct net *net = dev_net(skb->dev);
828 const struct inet6_protocol *ipprot;
829 enum skb_drop_reason reason;
830 int inner_offset;
831 __be16 frag_off;
832 u8 nexthdr;
833
834 reason = pskb_may_pull_reason(skb, sizeof(struct ipv6hdr));
835 if (reason != SKB_NOT_DROPPED_YET)
836 goto out;
837
838 seg6_icmp_srh(skb, opt);
839
840 nexthdr = ((struct ipv6hdr *)skb->data)->nexthdr;
841 if (ipv6_ext_hdr(nexthdr)) {
842 /* now skip over extension headers */
843 inner_offset = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr),
844 &nexthdr, &frag_off);
845 if (inner_offset < 0) {
846 SKB_DR_SET(reason, IPV6_BAD_EXTHDR);
847 goto out;
848 }
849 } else {
850 inner_offset = sizeof(struct ipv6hdr);
851 }
852
853 /* Checkin header including 8 bytes of inner protocol header. */
854 reason = pskb_may_pull_reason(skb, inner_offset + 8);
855 if (reason != SKB_NOT_DROPPED_YET)
856 goto out;
857
858 /* BUGGG_FUTURE: we should try to parse exthdrs in this packet.
859 Without this we will not able f.e. to make source routed
860 pmtu discovery.
861 Corresponding argument (opt) to notifiers is already added.
862 --ANK (980726)
863 */
864
865 ipprot = rcu_dereference(inet6_protos[nexthdr]);
866 if (ipprot && ipprot->err_handler)
867 ipprot->err_handler(skb, opt, type, code, inner_offset, info);
868
869 raw6_icmp_error(skb, nexthdr, type, code, inner_offset, info);
870 return SKB_CONSUMED;
871
872 out:
873 __ICMP6_INC_STATS(net, __in6_dev_get(skb->dev), ICMP6_MIB_INERRORS);
874 return reason;
875 }
876
877 /*
878 * Handle icmp messages
879 */
880
icmpv6_rcv(struct sk_buff * skb)881 static int icmpv6_rcv(struct sk_buff *skb)
882 {
883 enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED;
884 struct net *net = dev_net(skb->dev);
885 struct net_device *dev = icmp6_dev(skb);
886 struct inet6_dev *idev = __in6_dev_get(dev);
887 const struct in6_addr *saddr, *daddr;
888 struct icmp6hdr *hdr;
889 u8 type;
890
891 if (!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
892 struct sec_path *sp = skb_sec_path(skb);
893 int nh;
894
895 if (!(sp && sp->xvec[sp->len - 1]->props.flags &
896 XFRM_STATE_ICMP)) {
897 reason = SKB_DROP_REASON_XFRM_POLICY;
898 goto drop_no_count;
899 }
900
901 if (!pskb_may_pull(skb, sizeof(*hdr) + sizeof(struct ipv6hdr)))
902 goto drop_no_count;
903
904 nh = skb_network_offset(skb);
905 skb_set_network_header(skb, sizeof(*hdr));
906
907 if (!xfrm6_policy_check_reverse(NULL, XFRM_POLICY_IN,
908 skb)) {
909 reason = SKB_DROP_REASON_XFRM_POLICY;
910 goto drop_no_count;
911 }
912
913 skb_set_network_header(skb, nh);
914 }
915
916 __ICMP6_INC_STATS(dev_net(dev), idev, ICMP6_MIB_INMSGS);
917
918 saddr = &ipv6_hdr(skb)->saddr;
919 daddr = &ipv6_hdr(skb)->daddr;
920
921 if (skb_checksum_validate(skb, IPPROTO_ICMPV6, ip6_compute_pseudo)) {
922 net_dbg_ratelimited("ICMPv6 checksum failed [%pI6c > %pI6c]\n",
923 saddr, daddr);
924 goto csum_error;
925 }
926
927 if (!pskb_pull(skb, sizeof(*hdr)))
928 goto discard_it;
929
930 hdr = icmp6_hdr(skb);
931
932 type = hdr->icmp6_type;
933
934 ICMP6MSGIN_INC_STATS(dev_net(dev), idev, type);
935
936 switch (type) {
937 case ICMPV6_ECHO_REQUEST:
938 if (!net->ipv6.sysctl.icmpv6_echo_ignore_all)
939 reason = icmpv6_echo_reply(skb);
940 break;
941 case ICMPV6_EXT_ECHO_REQUEST:
942 if (!net->ipv6.sysctl.icmpv6_echo_ignore_all &&
943 READ_ONCE(net->ipv4.sysctl_icmp_echo_enable_probe))
944 reason = icmpv6_echo_reply(skb);
945 break;
946
947 case ICMPV6_ECHO_REPLY:
948 reason = ping_rcv(skb);
949 break;
950
951 case ICMPV6_EXT_ECHO_REPLY:
952 reason = ping_rcv(skb);
953 break;
954
955 case ICMPV6_PKT_TOOBIG:
956 /* BUGGG_FUTURE: if packet contains rthdr, we cannot update
957 standard destination cache. Seems, only "advanced"
958 destination cache will allow to solve this problem
959 --ANK (980726)
960 */
961 if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
962 goto discard_it;
963 hdr = icmp6_hdr(skb);
964
965 /* to notify */
966 fallthrough;
967 case ICMPV6_DEST_UNREACH:
968 case ICMPV6_TIME_EXCEED:
969 case ICMPV6_PARAMPROB:
970 reason = icmpv6_notify(skb, type, hdr->icmp6_code,
971 hdr->icmp6_mtu);
972 break;
973
974 case NDISC_ROUTER_SOLICITATION:
975 case NDISC_ROUTER_ADVERTISEMENT:
976 case NDISC_NEIGHBOUR_SOLICITATION:
977 case NDISC_NEIGHBOUR_ADVERTISEMENT:
978 case NDISC_REDIRECT:
979 reason = ndisc_rcv(skb);
980 break;
981
982 case ICMPV6_MGM_QUERY:
983 igmp6_event_query(skb);
984 return 0;
985
986 case ICMPV6_MGM_REPORT:
987 igmp6_event_report(skb);
988 return 0;
989
990 case ICMPV6_MGM_REDUCTION:
991 case ICMPV6_NI_QUERY:
992 case ICMPV6_NI_REPLY:
993 case ICMPV6_MLD2_REPORT:
994 case ICMPV6_DHAAD_REQUEST:
995 case ICMPV6_DHAAD_REPLY:
996 case ICMPV6_MOBILE_PREFIX_SOL:
997 case ICMPV6_MOBILE_PREFIX_ADV:
998 break;
999
1000 default:
1001 /* informational */
1002 if (type & ICMPV6_INFOMSG_MASK)
1003 break;
1004
1005 net_dbg_ratelimited("icmpv6: msg of unknown type [%pI6c > %pI6c]\n",
1006 saddr, daddr);
1007
1008 /*
1009 * error of unknown type.
1010 * must pass to upper level
1011 */
1012
1013 reason = icmpv6_notify(skb, type, hdr->icmp6_code,
1014 hdr->icmp6_mtu);
1015 }
1016
1017 /* until the v6 path can be better sorted assume failure and
1018 * preserve the status quo behaviour for the rest of the paths to here
1019 */
1020 if (reason)
1021 kfree_skb_reason(skb, reason);
1022 else
1023 consume_skb(skb);
1024
1025 return 0;
1026
1027 csum_error:
1028 reason = SKB_DROP_REASON_ICMP_CSUM;
1029 __ICMP6_INC_STATS(dev_net(dev), idev, ICMP6_MIB_CSUMERRORS);
1030 discard_it:
1031 __ICMP6_INC_STATS(dev_net(dev), idev, ICMP6_MIB_INERRORS);
1032 drop_no_count:
1033 kfree_skb_reason(skb, reason);
1034 return 0;
1035 }
1036
icmpv6_flow_init(const struct sock * sk,struct flowi6 * fl6,u8 type,const struct in6_addr * saddr,const struct in6_addr * daddr,int oif)1037 void icmpv6_flow_init(const struct sock *sk, struct flowi6 *fl6, u8 type,
1038 const struct in6_addr *saddr,
1039 const struct in6_addr *daddr, int oif)
1040 {
1041 memset(fl6, 0, sizeof(*fl6));
1042 fl6->saddr = *saddr;
1043 fl6->daddr = *daddr;
1044 fl6->flowi6_proto = IPPROTO_ICMPV6;
1045 fl6->fl6_icmp_type = type;
1046 fl6->fl6_icmp_code = 0;
1047 fl6->flowi6_oif = oif;
1048 security_sk_classify_flow(sk, flowi6_to_flowi_common(fl6));
1049 }
1050
icmpv6_init(void)1051 int __init icmpv6_init(void)
1052 {
1053 struct sock *sk;
1054 int err, i;
1055
1056 for_each_possible_cpu(i) {
1057 err = inet_ctl_sock_create(&sk, PF_INET6,
1058 SOCK_RAW, IPPROTO_ICMPV6, &init_net);
1059 if (err < 0) {
1060 pr_err("Failed to initialize the ICMP6 control socket (err %d)\n",
1061 err);
1062 return err;
1063 }
1064
1065 per_cpu(ipv6_icmp_sk, i) = sk;
1066
1067 /* Enough space for 2 64K ICMP packets, including
1068 * sk_buff struct overhead.
1069 */
1070 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024);
1071 }
1072
1073 err = -EAGAIN;
1074 if (inet6_add_protocol(&icmpv6_protocol, IPPROTO_ICMPV6) < 0)
1075 goto fail;
1076
1077 err = inet6_register_icmp_sender(icmp6_send);
1078 if (err)
1079 goto sender_reg_err;
1080 return 0;
1081
1082 sender_reg_err:
1083 inet6_del_protocol(&icmpv6_protocol, IPPROTO_ICMPV6);
1084 fail:
1085 pr_err("Failed to register ICMP6 protocol\n");
1086 return err;
1087 }
1088
icmpv6_cleanup(void)1089 void icmpv6_cleanup(void)
1090 {
1091 inet6_unregister_icmp_sender(icmp6_send);
1092 inet6_del_protocol(&icmpv6_protocol, IPPROTO_ICMPV6);
1093 }
1094
1095
1096 static const struct icmp6_err {
1097 int err;
1098 int fatal;
1099 } tab_unreach[] = {
1100 { /* NOROUTE */
1101 .err = ENETUNREACH,
1102 .fatal = 0,
1103 },
1104 { /* ADM_PROHIBITED */
1105 .err = EACCES,
1106 .fatal = 1,
1107 },
1108 { /* Was NOT_NEIGHBOUR, now reserved */
1109 .err = EHOSTUNREACH,
1110 .fatal = 0,
1111 },
1112 { /* ADDR_UNREACH */
1113 .err = EHOSTUNREACH,
1114 .fatal = 0,
1115 },
1116 { /* PORT_UNREACH */
1117 .err = ECONNREFUSED,
1118 .fatal = 1,
1119 },
1120 { /* POLICY_FAIL */
1121 .err = EACCES,
1122 .fatal = 1,
1123 },
1124 { /* REJECT_ROUTE */
1125 .err = EACCES,
1126 .fatal = 1,
1127 },
1128 };
1129
icmpv6_err_convert(u8 type,u8 code,int * err)1130 int icmpv6_err_convert(u8 type, u8 code, int *err)
1131 {
1132 int fatal = 0;
1133
1134 *err = EPROTO;
1135
1136 switch (type) {
1137 case ICMPV6_DEST_UNREACH:
1138 fatal = 1;
1139 if (code < ARRAY_SIZE(tab_unreach)) {
1140 *err = tab_unreach[code].err;
1141 fatal = tab_unreach[code].fatal;
1142 }
1143 break;
1144
1145 case ICMPV6_PKT_TOOBIG:
1146 *err = EMSGSIZE;
1147 break;
1148
1149 case ICMPV6_PARAMPROB:
1150 *err = EPROTO;
1151 fatal = 1;
1152 break;
1153
1154 case ICMPV6_TIME_EXCEED:
1155 *err = EHOSTUNREACH;
1156 break;
1157 }
1158
1159 return fatal;
1160 }
1161 EXPORT_SYMBOL(icmpv6_err_convert);
1162
1163 #ifdef CONFIG_SYSCTL
1164 static struct ctl_table ipv6_icmp_table_template[] = {
1165 {
1166 .procname = "ratelimit",
1167 .data = &init_net.ipv6.sysctl.icmpv6_time,
1168 .maxlen = sizeof(int),
1169 .mode = 0644,
1170 .proc_handler = proc_dointvec_ms_jiffies,
1171 },
1172 {
1173 .procname = "echo_ignore_all",
1174 .data = &init_net.ipv6.sysctl.icmpv6_echo_ignore_all,
1175 .maxlen = sizeof(u8),
1176 .mode = 0644,
1177 .proc_handler = proc_dou8vec_minmax,
1178 },
1179 {
1180 .procname = "echo_ignore_multicast",
1181 .data = &init_net.ipv6.sysctl.icmpv6_echo_ignore_multicast,
1182 .maxlen = sizeof(u8),
1183 .mode = 0644,
1184 .proc_handler = proc_dou8vec_minmax,
1185 },
1186 {
1187 .procname = "echo_ignore_anycast",
1188 .data = &init_net.ipv6.sysctl.icmpv6_echo_ignore_anycast,
1189 .maxlen = sizeof(u8),
1190 .mode = 0644,
1191 .proc_handler = proc_dou8vec_minmax,
1192 },
1193 {
1194 .procname = "ratemask",
1195 .data = &init_net.ipv6.sysctl.icmpv6_ratemask_ptr,
1196 .maxlen = ICMPV6_MSG_MAX + 1,
1197 .mode = 0644,
1198 .proc_handler = proc_do_large_bitmap,
1199 },
1200 {
1201 .procname = "error_anycast_as_unicast",
1202 .data = &init_net.ipv6.sysctl.icmpv6_error_anycast_as_unicast,
1203 .maxlen = sizeof(u8),
1204 .mode = 0644,
1205 .proc_handler = proc_dou8vec_minmax,
1206 .extra1 = SYSCTL_ZERO,
1207 .extra2 = SYSCTL_ONE,
1208 },
1209 { },
1210 };
1211
ipv6_icmp_sysctl_init(struct net * net)1212 struct ctl_table * __net_init ipv6_icmp_sysctl_init(struct net *net)
1213 {
1214 struct ctl_table *table;
1215
1216 table = kmemdup(ipv6_icmp_table_template,
1217 sizeof(ipv6_icmp_table_template),
1218 GFP_KERNEL);
1219
1220 if (table) {
1221 table[0].data = &net->ipv6.sysctl.icmpv6_time;
1222 table[1].data = &net->ipv6.sysctl.icmpv6_echo_ignore_all;
1223 table[2].data = &net->ipv6.sysctl.icmpv6_echo_ignore_multicast;
1224 table[3].data = &net->ipv6.sysctl.icmpv6_echo_ignore_anycast;
1225 table[4].data = &net->ipv6.sysctl.icmpv6_ratemask_ptr;
1226 table[5].data = &net->ipv6.sysctl.icmpv6_error_anycast_as_unicast;
1227 }
1228 return table;
1229 }
1230
ipv6_icmp_sysctl_table_size(void)1231 size_t ipv6_icmp_sysctl_table_size(void)
1232 {
1233 return ARRAY_SIZE(ipv6_icmp_table_template);
1234 }
1235 #endif
1236