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Linux/net/ipv6/icmp.c

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  1 /*
  2  *      Internet Control Message Protocol (ICMPv6)
  3  *      Linux INET6 implementation
  4  *
  5  *      Authors:
  6  *      Pedro Roque             <roque@di.fc.ul.pt>
  7  *
  8  *      Based on net/ipv4/icmp.c
  9  *
 10  *      RFC 1885
 11  *
 12  *      This program is free software; you can redistribute it and/or
 13  *      modify it under the terms of the GNU General Public License
 14  *      as published by the Free Software Foundation; either version
 15  *      2 of the License, or (at your option) any later version.
 16  */
 17 
 18 /*
 19  *      Changes:
 20  *
 21  *      Andi Kleen              :       exception handling
 22  *      Andi Kleen                      add rate limits. never reply to a icmp.
 23  *                                      add more length checks and other fixes.
 24  *      yoshfuji                :       ensure to sent parameter problem for
 25  *                                      fragments.
 26  *      YOSHIFUJI Hideaki @USAGI:       added sysctl for icmp rate limit.
 27  *      Randy Dunlap and
 28  *      YOSHIFUJI Hideaki @USAGI:       Per-interface statistics support
 29  *      Kazunori MIYAZAWA @USAGI:       change output process to use ip6_append_data
 30  */
 31 
 32 #define pr_fmt(fmt) "IPv6: " fmt
 33 
 34 #include <linux/module.h>
 35 #include <linux/errno.h>
 36 #include <linux/types.h>
 37 #include <linux/socket.h>
 38 #include <linux/in.h>
 39 #include <linux/kernel.h>
 40 #include <linux/sockios.h>
 41 #include <linux/net.h>
 42 #include <linux/skbuff.h>
 43 #include <linux/init.h>
 44 #include <linux/netfilter.h>
 45 #include <linux/slab.h>
 46 
 47 #ifdef CONFIG_SYSCTL
 48 #include <linux/sysctl.h>
 49 #endif
 50 
 51 #include <linux/inet.h>
 52 #include <linux/netdevice.h>
 53 #include <linux/icmpv6.h>
 54 
 55 #include <net/ip.h>
 56 #include <net/sock.h>
 57 
 58 #include <net/ipv6.h>
 59 #include <net/ip6_checksum.h>
 60 #include <net/ping.h>
 61 #include <net/protocol.h>
 62 #include <net/raw.h>
 63 #include <net/rawv6.h>
 64 #include <net/transp_v6.h>
 65 #include <net/ip6_route.h>
 66 #include <net/addrconf.h>
 67 #include <net/icmp.h>
 68 #include <net/xfrm.h>
 69 #include <net/inet_common.h>
 70 #include <net/dsfield.h>
 71 #include <net/l3mdev.h>
 72 
 73 #include <linux/uaccess.h>
 74 
 75 /*
 76  *      The ICMP socket(s). This is the most convenient way to flow control
 77  *      our ICMP output as well as maintain a clean interface throughout
 78  *      all layers. All Socketless IP sends will soon be gone.
 79  *
 80  *      On SMP we have one ICMP socket per-cpu.
 81  */
 82 static inline struct sock *icmpv6_sk(struct net *net)
 83 {
 84         return net->ipv6.icmp_sk[smp_processor_id()];
 85 }
 86 
 87 static void icmpv6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 88                        u8 type, u8 code, int offset, __be32 info)
 89 {
 90         /* icmpv6_notify checks 8 bytes can be pulled, icmp6hdr is 8 bytes */
 91         struct icmp6hdr *icmp6 = (struct icmp6hdr *) (skb->data + offset);
 92         struct net *net = dev_net(skb->dev);
 93 
 94         if (type == ICMPV6_PKT_TOOBIG)
 95                 ip6_update_pmtu(skb, net, info, 0, 0, sock_net_uid(net, NULL));
 96         else if (type == NDISC_REDIRECT)
 97                 ip6_redirect(skb, net, skb->dev->ifindex, 0,
 98                              sock_net_uid(net, NULL));
 99 
100         if (!(type & ICMPV6_INFOMSG_MASK))
101                 if (icmp6->icmp6_type == ICMPV6_ECHO_REQUEST)
102                         ping_err(skb, offset, ntohl(info));
103 }
104 
105 static int icmpv6_rcv(struct sk_buff *skb);
106 
107 static const struct inet6_protocol icmpv6_protocol = {
108         .handler        =       icmpv6_rcv,
109         .err_handler    =       icmpv6_err,
110         .flags          =       INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,
111 };
112 
113 /* Called with BH disabled */
114 static __inline__ struct sock *icmpv6_xmit_lock(struct net *net)
115 {
116         struct sock *sk;
117 
118         sk = icmpv6_sk(net);
119         if (unlikely(!spin_trylock(&sk->sk_lock.slock))) {
120                 /* This can happen if the output path (f.e. SIT or
121                  * ip6ip6 tunnel) signals dst_link_failure() for an
122                  * outgoing ICMP6 packet.
123                  */
124                 return NULL;
125         }
126         return sk;
127 }
128 
129 static __inline__ void icmpv6_xmit_unlock(struct sock *sk)
130 {
131         spin_unlock(&sk->sk_lock.slock);
132 }
133 
134 /*
135  * Figure out, may we reply to this packet with icmp error.
136  *
137  * We do not reply, if:
138  *      - it was icmp error message.
139  *      - it is truncated, so that it is known, that protocol is ICMPV6
140  *        (i.e. in the middle of some exthdr)
141  *
142  *      --ANK (980726)
143  */
144 
145 static bool is_ineligible(const struct sk_buff *skb)
146 {
147         int ptr = (u8 *)(ipv6_hdr(skb) + 1) - skb->data;
148         int len = skb->len - ptr;
149         __u8 nexthdr = ipv6_hdr(skb)->nexthdr;
150         __be16 frag_off;
151 
152         if (len < 0)
153                 return true;
154 
155         ptr = ipv6_skip_exthdr(skb, ptr, &nexthdr, &frag_off);
156         if (ptr < 0)
157                 return false;
158         if (nexthdr == IPPROTO_ICMPV6) {
159                 u8 _type, *tp;
160                 tp = skb_header_pointer(skb,
161                         ptr+offsetof(struct icmp6hdr, icmp6_type),
162                         sizeof(_type), &_type);
163                 if (!tp || !(*tp & ICMPV6_INFOMSG_MASK))
164                         return true;
165         }
166         return false;
167 }
168 
169 static bool icmpv6_mask_allow(int type)
170 {
171         /* Informational messages are not limited. */
172         if (type & ICMPV6_INFOMSG_MASK)
173                 return true;
174 
175         /* Do not limit pmtu discovery, it would break it. */
176         if (type == ICMPV6_PKT_TOOBIG)
177                 return true;
178 
179         return false;
180 }
181 
182 static bool icmpv6_global_allow(int type)
183 {
184         if (icmpv6_mask_allow(type))
185                 return true;
186 
187         if (icmp_global_allow())
188                 return true;
189 
190         return false;
191 }
192 
193 /*
194  * Check the ICMP output rate limit
195  */
196 static bool icmpv6_xrlim_allow(struct sock *sk, u8 type,
197                                struct flowi6 *fl6)
198 {
199         struct net *net = sock_net(sk);
200         struct dst_entry *dst;
201         bool res = false;
202 
203         if (icmpv6_mask_allow(type))
204                 return true;
205 
206         /*
207          * Look up the output route.
208          * XXX: perhaps the expire for routing entries cloned by
209          * this lookup should be more aggressive (not longer than timeout).
210          */
211         dst = ip6_route_output(net, sk, fl6);
212         if (dst->error) {
213                 IP6_INC_STATS(net, ip6_dst_idev(dst),
214                               IPSTATS_MIB_OUTNOROUTES);
215         } else if (dst->dev && (dst->dev->flags&IFF_LOOPBACK)) {
216                 res = true;
217         } else {
218                 struct rt6_info *rt = (struct rt6_info *)dst;
219                 int tmo = net->ipv6.sysctl.icmpv6_time;
220                 struct inet_peer *peer;
221 
222                 /* Give more bandwidth to wider prefixes. */
223                 if (rt->rt6i_dst.plen < 128)
224                         tmo >>= ((128 - rt->rt6i_dst.plen)>>5);
225 
226                 peer = inet_getpeer_v6(net->ipv6.peers, &fl6->daddr, 1);
227                 res = inet_peer_xrlim_allow(peer, tmo);
228                 if (peer)
229                         inet_putpeer(peer);
230         }
231         dst_release(dst);
232         return res;
233 }
234 
235 /*
236  *      an inline helper for the "simple" if statement below
237  *      checks if parameter problem report is caused by an
238  *      unrecognized IPv6 option that has the Option Type
239  *      highest-order two bits set to 10
240  */
241 
242 static bool opt_unrec(struct sk_buff *skb, __u32 offset)
243 {
244         u8 _optval, *op;
245 
246         offset += skb_network_offset(skb);
247         op = skb_header_pointer(skb, offset, sizeof(_optval), &_optval);
248         if (!op)
249                 return true;
250         return (*op & 0xC0) == 0x80;
251 }
252 
253 void icmpv6_push_pending_frames(struct sock *sk, struct flowi6 *fl6,
254                                 struct icmp6hdr *thdr, int len)
255 {
256         struct sk_buff *skb;
257         struct icmp6hdr *icmp6h;
258 
259         skb = skb_peek(&sk->sk_write_queue);
260         if (!skb)
261                 return;
262 
263         icmp6h = icmp6_hdr(skb);
264         memcpy(icmp6h, thdr, sizeof(struct icmp6hdr));
265         icmp6h->icmp6_cksum = 0;
266 
267         if (skb_queue_len(&sk->sk_write_queue) == 1) {
268                 skb->csum = csum_partial(icmp6h,
269                                         sizeof(struct icmp6hdr), skb->csum);
270                 icmp6h->icmp6_cksum = csum_ipv6_magic(&fl6->saddr,
271                                                       &fl6->daddr,
272                                                       len, fl6->flowi6_proto,
273                                                       skb->csum);
274         } else {
275                 __wsum tmp_csum = 0;
276 
277                 skb_queue_walk(&sk->sk_write_queue, skb) {
278                         tmp_csum = csum_add(tmp_csum, skb->csum);
279                 }
280 
281                 tmp_csum = csum_partial(icmp6h,
282                                         sizeof(struct icmp6hdr), tmp_csum);
283                 icmp6h->icmp6_cksum = csum_ipv6_magic(&fl6->saddr,
284                                                       &fl6->daddr,
285                                                       len, fl6->flowi6_proto,
286                                                       tmp_csum);
287         }
288         ip6_push_pending_frames(sk);
289 }
290 
291 struct icmpv6_msg {
292         struct sk_buff  *skb;
293         int             offset;
294         uint8_t         type;
295 };
296 
297 static int icmpv6_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
298 {
299         struct icmpv6_msg *msg = (struct icmpv6_msg *) from;
300         struct sk_buff *org_skb = msg->skb;
301         __wsum csum = 0;
302 
303         csum = skb_copy_and_csum_bits(org_skb, msg->offset + offset,
304                                       to, len, csum);
305         skb->csum = csum_block_add(skb->csum, csum, odd);
306         if (!(msg->type & ICMPV6_INFOMSG_MASK))
307                 nf_ct_attach(skb, org_skb);
308         return 0;
309 }
310 
311 #if IS_ENABLED(CONFIG_IPV6_MIP6)
312 static void mip6_addr_swap(struct sk_buff *skb)
313 {
314         struct ipv6hdr *iph = ipv6_hdr(skb);
315         struct inet6_skb_parm *opt = IP6CB(skb);
316         struct ipv6_destopt_hao *hao;
317         struct in6_addr tmp;
318         int off;
319 
320         if (opt->dsthao) {
321                 off = ipv6_find_tlv(skb, opt->dsthao, IPV6_TLV_HAO);
322                 if (likely(off >= 0)) {
323                         hao = (struct ipv6_destopt_hao *)
324                                         (skb_network_header(skb) + off);
325                         tmp = iph->saddr;
326                         iph->saddr = hao->addr;
327                         hao->addr = tmp;
328                 }
329         }
330 }
331 #else
332 static inline void mip6_addr_swap(struct sk_buff *skb) {}
333 #endif
334 
335 static struct dst_entry *icmpv6_route_lookup(struct net *net,
336                                              struct sk_buff *skb,
337                                              struct sock *sk,
338                                              struct flowi6 *fl6)
339 {
340         struct dst_entry *dst, *dst2;
341         struct flowi6 fl2;
342         int err;
343 
344         err = ip6_dst_lookup(net, sk, &dst, fl6);
345         if (err)
346                 return ERR_PTR(err);
347 
348         /*
349          * We won't send icmp if the destination is known
350          * anycast.
351          */
352         if (ipv6_anycast_destination(dst, &fl6->daddr)) {
353                 net_dbg_ratelimited("icmp6_send: acast source\n");
354                 dst_release(dst);
355                 return ERR_PTR(-EINVAL);
356         }
357 
358         /* No need to clone since we're just using its address. */
359         dst2 = dst;
360 
361         dst = xfrm_lookup(net, dst, flowi6_to_flowi(fl6), sk, 0);
362         if (!IS_ERR(dst)) {
363                 if (dst != dst2)
364                         return dst;
365         } else {
366                 if (PTR_ERR(dst) == -EPERM)
367                         dst = NULL;
368                 else
369                         return dst;
370         }
371 
372         err = xfrm_decode_session_reverse(skb, flowi6_to_flowi(&fl2), AF_INET6);
373         if (err)
374                 goto relookup_failed;
375 
376         err = ip6_dst_lookup(net, sk, &dst2, &fl2);
377         if (err)
378                 goto relookup_failed;
379 
380         dst2 = xfrm_lookup(net, dst2, flowi6_to_flowi(&fl2), sk, XFRM_LOOKUP_ICMP);
381         if (!IS_ERR(dst2)) {
382                 dst_release(dst);
383                 dst = dst2;
384         } else {
385                 err = PTR_ERR(dst2);
386                 if (err == -EPERM) {
387                         dst_release(dst);
388                         return dst2;
389                 } else
390                         goto relookup_failed;
391         }
392 
393 relookup_failed:
394         if (dst)
395                 return dst;
396         return ERR_PTR(err);
397 }
398 
399 static int icmp6_iif(const struct sk_buff *skb)
400 {
401         int iif = skb->dev->ifindex;
402 
403         /* for local traffic to local address, skb dev is the loopback
404          * device. Check if there is a dst attached to the skb and if so
405          * get the real device index. Same is needed for replies to a link
406          * local address on a device enslaved to an L3 master device
407          */
408         if (unlikely(iif == LOOPBACK_IFINDEX || netif_is_l3_master(skb->dev))) {
409                 const struct rt6_info *rt6 = skb_rt6_info(skb);
410 
411                 if (rt6)
412                         iif = rt6->rt6i_idev->dev->ifindex;
413         }
414 
415         return iif;
416 }
417 
418 /*
419  *      Send an ICMP message in response to a packet in error
420  */
421 static void icmp6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info,
422                        const struct in6_addr *force_saddr)
423 {
424         struct net *net = dev_net(skb->dev);
425         struct inet6_dev *idev = NULL;
426         struct ipv6hdr *hdr = ipv6_hdr(skb);
427         struct sock *sk;
428         struct ipv6_pinfo *np;
429         const struct in6_addr *saddr = NULL;
430         struct dst_entry *dst;
431         struct icmp6hdr tmp_hdr;
432         struct flowi6 fl6;
433         struct icmpv6_msg msg;
434         struct sockcm_cookie sockc_unused = {0};
435         struct ipcm6_cookie ipc6;
436         int iif = 0;
437         int addr_type = 0;
438         int len;
439         u32 mark = IP6_REPLY_MARK(net, skb->mark);
440 
441         if ((u8 *)hdr < skb->head ||
442             (skb_network_header(skb) + sizeof(*hdr)) > skb_tail_pointer(skb))
443                 return;
444 
445         /*
446          *      Make sure we respect the rules
447          *      i.e. RFC 1885 2.4(e)
448          *      Rule (e.1) is enforced by not using icmp6_send
449          *      in any code that processes icmp errors.
450          */
451         addr_type = ipv6_addr_type(&hdr->daddr);
452 
453         if (ipv6_chk_addr(net, &hdr->daddr, skb->dev, 0) ||
454             ipv6_chk_acast_addr_src(net, skb->dev, &hdr->daddr))
455                 saddr = &hdr->daddr;
456 
457         /*
458          *      Dest addr check
459          */
460 
461         if (addr_type & IPV6_ADDR_MULTICAST || skb->pkt_type != PACKET_HOST) {
462                 if (type != ICMPV6_PKT_TOOBIG &&
463                     !(type == ICMPV6_PARAMPROB &&
464                       code == ICMPV6_UNK_OPTION &&
465                       (opt_unrec(skb, info))))
466                         return;
467 
468                 saddr = NULL;
469         }
470 
471         addr_type = ipv6_addr_type(&hdr->saddr);
472 
473         /*
474          *      Source addr check
475          */
476 
477         if (__ipv6_addr_needs_scope_id(addr_type)) {
478                 iif = icmp6_iif(skb);
479         } else {
480                 dst = skb_dst(skb);
481                 iif = l3mdev_master_ifindex(dst ? dst->dev : skb->dev);
482         }
483 
484         /*
485          *      Must not send error if the source does not uniquely
486          *      identify a single node (RFC2463 Section 2.4).
487          *      We check unspecified / multicast addresses here,
488          *      and anycast addresses will be checked later.
489          */
490         if ((addr_type == IPV6_ADDR_ANY) || (addr_type & IPV6_ADDR_MULTICAST)) {
491                 net_dbg_ratelimited("icmp6_send: addr_any/mcast source [%pI6c > %pI6c]\n",
492                                     &hdr->saddr, &hdr->daddr);
493                 return;
494         }
495 
496         /*
497          *      Never answer to a ICMP packet.
498          */
499         if (is_ineligible(skb)) {
500                 net_dbg_ratelimited("icmp6_send: no reply to icmp error [%pI6c > %pI6c]\n",
501                                     &hdr->saddr, &hdr->daddr);
502                 return;
503         }
504 
505         /* Needed by both icmp_global_allow and icmpv6_xmit_lock */
506         local_bh_disable();
507 
508         /* Check global sysctl_icmp_msgs_per_sec ratelimit */
509         if (!(skb->dev->flags&IFF_LOOPBACK) && !icmpv6_global_allow(type))
510                 goto out_bh_enable;
511 
512         mip6_addr_swap(skb);
513 
514         memset(&fl6, 0, sizeof(fl6));
515         fl6.flowi6_proto = IPPROTO_ICMPV6;
516         fl6.daddr = hdr->saddr;
517         if (force_saddr)
518                 saddr = force_saddr;
519         if (saddr)
520                 fl6.saddr = *saddr;
521         fl6.flowi6_mark = mark;
522         fl6.flowi6_oif = iif;
523         fl6.fl6_icmp_type = type;
524         fl6.fl6_icmp_code = code;
525         fl6.flowi6_uid = sock_net_uid(net, NULL);
526         fl6.mp_hash = rt6_multipath_hash(net, &fl6, skb, NULL);
527         security_skb_classify_flow(skb, flowi6_to_flowi(&fl6));
528 
529         sk = icmpv6_xmit_lock(net);
530         if (!sk)
531                 goto out_bh_enable;
532 
533         sk->sk_mark = mark;
534         np = inet6_sk(sk);
535 
536         if (!icmpv6_xrlim_allow(sk, type, &fl6))
537                 goto out;
538 
539         tmp_hdr.icmp6_type = type;
540         tmp_hdr.icmp6_code = code;
541         tmp_hdr.icmp6_cksum = 0;
542         tmp_hdr.icmp6_pointer = htonl(info);
543 
544         if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
545                 fl6.flowi6_oif = np->mcast_oif;
546         else if (!fl6.flowi6_oif)
547                 fl6.flowi6_oif = np->ucast_oif;
548 
549         ipc6.tclass = np->tclass;
550         fl6.flowlabel = ip6_make_flowinfo(ipc6.tclass, fl6.flowlabel);
551 
552         dst = icmpv6_route_lookup(net, skb, sk, &fl6);
553         if (IS_ERR(dst))
554                 goto out;
555 
556         ipc6.hlimit = ip6_sk_dst_hoplimit(np, &fl6, dst);
557         ipc6.dontfrag = np->dontfrag;
558         ipc6.opt = NULL;
559 
560         msg.skb = skb;
561         msg.offset = skb_network_offset(skb);
562         msg.type = type;
563 
564         len = skb->len - msg.offset;
565         len = min_t(unsigned int, len, IPV6_MIN_MTU - sizeof(struct ipv6hdr) - sizeof(struct icmp6hdr));
566         if (len < 0) {
567                 net_dbg_ratelimited("icmp: len problem [%pI6c > %pI6c]\n",
568                                     &hdr->saddr, &hdr->daddr);
569                 goto out_dst_release;
570         }
571 
572         rcu_read_lock();
573         idev = __in6_dev_get(skb->dev);
574 
575         if (ip6_append_data(sk, icmpv6_getfrag, &msg,
576                             len + sizeof(struct icmp6hdr),
577                             sizeof(struct icmp6hdr),
578                             &ipc6, &fl6, (struct rt6_info *)dst,
579                             MSG_DONTWAIT, &sockc_unused)) {
580                 ICMP6_INC_STATS(net, idev, ICMP6_MIB_OUTERRORS);
581                 ip6_flush_pending_frames(sk);
582         } else {
583                 icmpv6_push_pending_frames(sk, &fl6, &tmp_hdr,
584                                            len + sizeof(struct icmp6hdr));
585         }
586         rcu_read_unlock();
587 out_dst_release:
588         dst_release(dst);
589 out:
590         icmpv6_xmit_unlock(sk);
591 out_bh_enable:
592         local_bh_enable();
593 }
594 
595 /* Slightly more convenient version of icmp6_send.
596  */
597 void icmpv6_param_prob(struct sk_buff *skb, u8 code, int pos)
598 {
599         icmp6_send(skb, ICMPV6_PARAMPROB, code, pos, NULL);
600         kfree_skb(skb);
601 }
602 
603 /* Generate icmpv6 with type/code ICMPV6_DEST_UNREACH/ICMPV6_ADDR_UNREACH
604  * if sufficient data bytes are available
605  * @nhs is the size of the tunnel header(s) :
606  *  Either an IPv4 header for SIT encap
607  *         an IPv4 header + GRE header for GRE encap
608  */
609 int ip6_err_gen_icmpv6_unreach(struct sk_buff *skb, int nhs, int type,
610                                unsigned int data_len)
611 {
612         struct in6_addr temp_saddr;
613         struct rt6_info *rt;
614         struct sk_buff *skb2;
615         u32 info = 0;
616 
617         if (!pskb_may_pull(skb, nhs + sizeof(struct ipv6hdr) + 8))
618                 return 1;
619 
620         /* RFC 4884 (partial) support for ICMP extensions */
621         if (data_len < 128 || (data_len & 7) || skb->len < data_len)
622                 data_len = 0;
623 
624         skb2 = data_len ? skb_copy(skb, GFP_ATOMIC) : skb_clone(skb, GFP_ATOMIC);
625 
626         if (!skb2)
627                 return 1;
628 
629         skb_dst_drop(skb2);
630         skb_pull(skb2, nhs);
631         skb_reset_network_header(skb2);
632 
633         rt = rt6_lookup(dev_net(skb->dev), &ipv6_hdr(skb2)->saddr, NULL, 0,
634                         skb, 0);
635 
636         if (rt && rt->dst.dev)
637                 skb2->dev = rt->dst.dev;
638 
639         ipv6_addr_set_v4mapped(ip_hdr(skb)->saddr, &temp_saddr);
640 
641         if (data_len) {
642                 /* RFC 4884 (partial) support :
643                  * insert 0 padding at the end, before the extensions
644                  */
645                 __skb_push(skb2, nhs);
646                 skb_reset_network_header(skb2);
647                 memmove(skb2->data, skb2->data + nhs, data_len - nhs);
648                 memset(skb2->data + data_len - nhs, 0, nhs);
649                 /* RFC 4884 4.5 : Length is measured in 64-bit words,
650                  * and stored in reserved[0]
651                  */
652                 info = (data_len/8) << 24;
653         }
654         if (type == ICMP_TIME_EXCEEDED)
655                 icmp6_send(skb2, ICMPV6_TIME_EXCEED, ICMPV6_EXC_HOPLIMIT,
656                            info, &temp_saddr);
657         else
658                 icmp6_send(skb2, ICMPV6_DEST_UNREACH, ICMPV6_ADDR_UNREACH,
659                            info, &temp_saddr);
660         if (rt)
661                 ip6_rt_put(rt);
662 
663         kfree_skb(skb2);
664 
665         return 0;
666 }
667 EXPORT_SYMBOL(ip6_err_gen_icmpv6_unreach);
668 
669 static void icmpv6_echo_reply(struct sk_buff *skb)
670 {
671         struct net *net = dev_net(skb->dev);
672         struct sock *sk;
673         struct inet6_dev *idev;
674         struct ipv6_pinfo *np;
675         const struct in6_addr *saddr = NULL;
676         struct icmp6hdr *icmph = icmp6_hdr(skb);
677         struct icmp6hdr tmp_hdr;
678         struct flowi6 fl6;
679         struct icmpv6_msg msg;
680         struct dst_entry *dst;
681         struct ipcm6_cookie ipc6;
682         u32 mark = IP6_REPLY_MARK(net, skb->mark);
683         struct sockcm_cookie sockc_unused = {0};
684 
685         saddr = &ipv6_hdr(skb)->daddr;
686 
687         if (!ipv6_unicast_destination(skb) &&
688             !(net->ipv6.sysctl.anycast_src_echo_reply &&
689               ipv6_anycast_destination(skb_dst(skb), saddr)))
690                 saddr = NULL;
691 
692         memcpy(&tmp_hdr, icmph, sizeof(tmp_hdr));
693         tmp_hdr.icmp6_type = ICMPV6_ECHO_REPLY;
694 
695         memset(&fl6, 0, sizeof(fl6));
696         fl6.flowi6_proto = IPPROTO_ICMPV6;
697         fl6.daddr = ipv6_hdr(skb)->saddr;
698         if (saddr)
699                 fl6.saddr = *saddr;
700         fl6.flowi6_oif = icmp6_iif(skb);
701         fl6.fl6_icmp_type = ICMPV6_ECHO_REPLY;
702         fl6.flowi6_mark = mark;
703         fl6.flowi6_uid = sock_net_uid(net, NULL);
704         security_skb_classify_flow(skb, flowi6_to_flowi(&fl6));
705 
706         local_bh_disable();
707         sk = icmpv6_xmit_lock(net);
708         if (!sk)
709                 goto out_bh_enable;
710         sk->sk_mark = mark;
711         np = inet6_sk(sk);
712 
713         if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
714                 fl6.flowi6_oif = np->mcast_oif;
715         else if (!fl6.flowi6_oif)
716                 fl6.flowi6_oif = np->ucast_oif;
717 
718         if (ip6_dst_lookup(net, sk, &dst, &fl6))
719                 goto out;
720         dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), sk, 0);
721         if (IS_ERR(dst))
722                 goto out;
723 
724         idev = __in6_dev_get(skb->dev);
725 
726         msg.skb = skb;
727         msg.offset = 0;
728         msg.type = ICMPV6_ECHO_REPLY;
729 
730         ipc6.hlimit = ip6_sk_dst_hoplimit(np, &fl6, dst);
731         ipc6.tclass = ipv6_get_dsfield(ipv6_hdr(skb));
732         ipc6.dontfrag = np->dontfrag;
733         ipc6.opt = NULL;
734 
735         if (ip6_append_data(sk, icmpv6_getfrag, &msg,
736                             skb->len + sizeof(struct icmp6hdr),
737                             sizeof(struct icmp6hdr), &ipc6, &fl6,
738                             (struct rt6_info *)dst, MSG_DONTWAIT,
739                             &sockc_unused)) {
740                 __ICMP6_INC_STATS(net, idev, ICMP6_MIB_OUTERRORS);
741                 ip6_flush_pending_frames(sk);
742         } else {
743                 icmpv6_push_pending_frames(sk, &fl6, &tmp_hdr,
744                                            skb->len + sizeof(struct icmp6hdr));
745         }
746         dst_release(dst);
747 out:
748         icmpv6_xmit_unlock(sk);
749 out_bh_enable:
750         local_bh_enable();
751 }
752 
753 void icmpv6_notify(struct sk_buff *skb, u8 type, u8 code, __be32 info)
754 {
755         const struct inet6_protocol *ipprot;
756         int inner_offset;
757         __be16 frag_off;
758         u8 nexthdr;
759         struct net *net = dev_net(skb->dev);
760 
761         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
762                 goto out;
763 
764         nexthdr = ((struct ipv6hdr *)skb->data)->nexthdr;
765         if (ipv6_ext_hdr(nexthdr)) {
766                 /* now skip over extension headers */
767                 inner_offset = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr),
768                                                 &nexthdr, &frag_off);
769                 if (inner_offset < 0)
770                         goto out;
771         } else {
772                 inner_offset = sizeof(struct ipv6hdr);
773         }
774 
775         /* Checkin header including 8 bytes of inner protocol header. */
776         if (!pskb_may_pull(skb, inner_offset+8))
777                 goto out;
778 
779         /* BUGGG_FUTURE: we should try to parse exthdrs in this packet.
780            Without this we will not able f.e. to make source routed
781            pmtu discovery.
782            Corresponding argument (opt) to notifiers is already added.
783            --ANK (980726)
784          */
785 
786         ipprot = rcu_dereference(inet6_protos[nexthdr]);
787         if (ipprot && ipprot->err_handler)
788                 ipprot->err_handler(skb, NULL, type, code, inner_offset, info);
789 
790         raw6_icmp_error(skb, nexthdr, type, code, inner_offset, info);
791         return;
792 
793 out:
794         __ICMP6_INC_STATS(net, __in6_dev_get(skb->dev), ICMP6_MIB_INERRORS);
795 }
796 
797 /*
798  *      Handle icmp messages
799  */
800 
801 static int icmpv6_rcv(struct sk_buff *skb)
802 {
803         struct net_device *dev = skb->dev;
804         struct inet6_dev *idev = __in6_dev_get(dev);
805         const struct in6_addr *saddr, *daddr;
806         struct icmp6hdr *hdr;
807         u8 type;
808         bool success = false;
809 
810         if (!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
811                 struct sec_path *sp = skb_sec_path(skb);
812                 int nh;
813 
814                 if (!(sp && sp->xvec[sp->len - 1]->props.flags &
815                                  XFRM_STATE_ICMP))
816                         goto drop_no_count;
817 
818                 if (!pskb_may_pull(skb, sizeof(*hdr) + sizeof(struct ipv6hdr)))
819                         goto drop_no_count;
820 
821                 nh = skb_network_offset(skb);
822                 skb_set_network_header(skb, sizeof(*hdr));
823 
824                 if (!xfrm6_policy_check_reverse(NULL, XFRM_POLICY_IN, skb))
825                         goto drop_no_count;
826 
827                 skb_set_network_header(skb, nh);
828         }
829 
830         __ICMP6_INC_STATS(dev_net(dev), idev, ICMP6_MIB_INMSGS);
831 
832         saddr = &ipv6_hdr(skb)->saddr;
833         daddr = &ipv6_hdr(skb)->daddr;
834 
835         if (skb_checksum_validate(skb, IPPROTO_ICMPV6, ip6_compute_pseudo)) {
836                 net_dbg_ratelimited("ICMPv6 checksum failed [%pI6c > %pI6c]\n",
837                                     saddr, daddr);
838                 goto csum_error;
839         }
840 
841         if (!pskb_pull(skb, sizeof(*hdr)))
842                 goto discard_it;
843 
844         hdr = icmp6_hdr(skb);
845 
846         type = hdr->icmp6_type;
847 
848         ICMP6MSGIN_INC_STATS(dev_net(dev), idev, type);
849 
850         switch (type) {
851         case ICMPV6_ECHO_REQUEST:
852                 icmpv6_echo_reply(skb);
853                 break;
854 
855         case ICMPV6_ECHO_REPLY:
856                 success = ping_rcv(skb);
857                 break;
858 
859         case ICMPV6_PKT_TOOBIG:
860                 /* BUGGG_FUTURE: if packet contains rthdr, we cannot update
861                    standard destination cache. Seems, only "advanced"
862                    destination cache will allow to solve this problem
863                    --ANK (980726)
864                  */
865                 if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
866                         goto discard_it;
867                 hdr = icmp6_hdr(skb);
868 
869                 /* to notify */
870                 /* fall through */
871         case ICMPV6_DEST_UNREACH:
872         case ICMPV6_TIME_EXCEED:
873         case ICMPV6_PARAMPROB:
874                 icmpv6_notify(skb, type, hdr->icmp6_code, hdr->icmp6_mtu);
875                 break;
876 
877         case NDISC_ROUTER_SOLICITATION:
878         case NDISC_ROUTER_ADVERTISEMENT:
879         case NDISC_NEIGHBOUR_SOLICITATION:
880         case NDISC_NEIGHBOUR_ADVERTISEMENT:
881         case NDISC_REDIRECT:
882                 ndisc_rcv(skb);
883                 break;
884 
885         case ICMPV6_MGM_QUERY:
886                 igmp6_event_query(skb);
887                 break;
888 
889         case ICMPV6_MGM_REPORT:
890                 igmp6_event_report(skb);
891                 break;
892 
893         case ICMPV6_MGM_REDUCTION:
894         case ICMPV6_NI_QUERY:
895         case ICMPV6_NI_REPLY:
896         case ICMPV6_MLD2_REPORT:
897         case ICMPV6_DHAAD_REQUEST:
898         case ICMPV6_DHAAD_REPLY:
899         case ICMPV6_MOBILE_PREFIX_SOL:
900         case ICMPV6_MOBILE_PREFIX_ADV:
901                 break;
902 
903         default:
904                 /* informational */
905                 if (type & ICMPV6_INFOMSG_MASK)
906                         break;
907 
908                 net_dbg_ratelimited("icmpv6: msg of unknown type [%pI6c > %pI6c]\n",
909                                     saddr, daddr);
910 
911                 /*
912                  * error of unknown type.
913                  * must pass to upper level
914                  */
915 
916                 icmpv6_notify(skb, type, hdr->icmp6_code, hdr->icmp6_mtu);
917         }
918 
919         /* until the v6 path can be better sorted assume failure and
920          * preserve the status quo behaviour for the rest of the paths to here
921          */
922         if (success)
923                 consume_skb(skb);
924         else
925                 kfree_skb(skb);
926 
927         return 0;
928 
929 csum_error:
930         __ICMP6_INC_STATS(dev_net(dev), idev, ICMP6_MIB_CSUMERRORS);
931 discard_it:
932         __ICMP6_INC_STATS(dev_net(dev), idev, ICMP6_MIB_INERRORS);
933 drop_no_count:
934         kfree_skb(skb);
935         return 0;
936 }
937 
938 void icmpv6_flow_init(struct sock *sk, struct flowi6 *fl6,
939                       u8 type,
940                       const struct in6_addr *saddr,
941                       const struct in6_addr *daddr,
942                       int oif)
943 {
944         memset(fl6, 0, sizeof(*fl6));
945         fl6->saddr = *saddr;
946         fl6->daddr = *daddr;
947         fl6->flowi6_proto       = IPPROTO_ICMPV6;
948         fl6->fl6_icmp_type      = type;
949         fl6->fl6_icmp_code      = 0;
950         fl6->flowi6_oif         = oif;
951         security_sk_classify_flow(sk, flowi6_to_flowi(fl6));
952 }
953 
954 static int __net_init icmpv6_sk_init(struct net *net)
955 {
956         struct sock *sk;
957         int err, i, j;
958 
959         net->ipv6.icmp_sk =
960                 kcalloc(nr_cpu_ids, sizeof(struct sock *), GFP_KERNEL);
961         if (!net->ipv6.icmp_sk)
962                 return -ENOMEM;
963 
964         for_each_possible_cpu(i) {
965                 err = inet_ctl_sock_create(&sk, PF_INET6,
966                                            SOCK_RAW, IPPROTO_ICMPV6, net);
967                 if (err < 0) {
968                         pr_err("Failed to initialize the ICMP6 control socket (err %d)\n",
969                                err);
970                         goto fail;
971                 }
972 
973                 net->ipv6.icmp_sk[i] = sk;
974 
975                 /* Enough space for 2 64K ICMP packets, including
976                  * sk_buff struct overhead.
977                  */
978                 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024);
979         }
980         return 0;
981 
982  fail:
983         for (j = 0; j < i; j++)
984                 inet_ctl_sock_destroy(net->ipv6.icmp_sk[j]);
985         kfree(net->ipv6.icmp_sk);
986         return err;
987 }
988 
989 static void __net_exit icmpv6_sk_exit(struct net *net)
990 {
991         int i;
992 
993         for_each_possible_cpu(i) {
994                 inet_ctl_sock_destroy(net->ipv6.icmp_sk[i]);
995         }
996         kfree(net->ipv6.icmp_sk);
997 }
998 
999 static struct pernet_operations icmpv6_sk_ops = {
1000         .init = icmpv6_sk_init,
1001         .exit = icmpv6_sk_exit,
1002 };
1003 
1004 int __init icmpv6_init(void)
1005 {
1006         int err;
1007 
1008         err = register_pernet_subsys(&icmpv6_sk_ops);
1009         if (err < 0)
1010                 return err;
1011 
1012         err = -EAGAIN;
1013         if (inet6_add_protocol(&icmpv6_protocol, IPPROTO_ICMPV6) < 0)
1014                 goto fail;
1015 
1016         err = inet6_register_icmp_sender(icmp6_send);
1017         if (err)
1018                 goto sender_reg_err;
1019         return 0;
1020 
1021 sender_reg_err:
1022         inet6_del_protocol(&icmpv6_protocol, IPPROTO_ICMPV6);
1023 fail:
1024         pr_err("Failed to register ICMP6 protocol\n");
1025         unregister_pernet_subsys(&icmpv6_sk_ops);
1026         return err;
1027 }
1028 
1029 void icmpv6_cleanup(void)
1030 {
1031         inet6_unregister_icmp_sender(icmp6_send);
1032         unregister_pernet_subsys(&icmpv6_sk_ops);
1033         inet6_del_protocol(&icmpv6_protocol, IPPROTO_ICMPV6);
1034 }
1035 
1036 
1037 static const struct icmp6_err {
1038         int err;
1039         int fatal;
1040 } tab_unreach[] = {
1041         {       /* NOROUTE */
1042                 .err    = ENETUNREACH,
1043                 .fatal  = 0,
1044         },
1045         {       /* ADM_PROHIBITED */
1046                 .err    = EACCES,
1047                 .fatal  = 1,
1048         },
1049         {       /* Was NOT_NEIGHBOUR, now reserved */
1050                 .err    = EHOSTUNREACH,
1051                 .fatal  = 0,
1052         },
1053         {       /* ADDR_UNREACH */
1054                 .err    = EHOSTUNREACH,
1055                 .fatal  = 0,
1056         },
1057         {       /* PORT_UNREACH */
1058                 .err    = ECONNREFUSED,
1059                 .fatal  = 1,
1060         },
1061         {       /* POLICY_FAIL */
1062                 .err    = EACCES,
1063                 .fatal  = 1,
1064         },
1065         {       /* REJECT_ROUTE */
1066                 .err    = EACCES,
1067                 .fatal  = 1,
1068         },
1069 };
1070 
1071 int icmpv6_err_convert(u8 type, u8 code, int *err)
1072 {
1073         int fatal = 0;
1074 
1075         *err = EPROTO;
1076 
1077         switch (type) {
1078         case ICMPV6_DEST_UNREACH:
1079                 fatal = 1;
1080                 if (code < ARRAY_SIZE(tab_unreach)) {
1081                         *err  = tab_unreach[code].err;
1082                         fatal = tab_unreach[code].fatal;
1083                 }
1084                 break;
1085 
1086         case ICMPV6_PKT_TOOBIG:
1087                 *err = EMSGSIZE;
1088                 break;
1089 
1090         case ICMPV6_PARAMPROB:
1091                 *err = EPROTO;
1092                 fatal = 1;
1093                 break;
1094 
1095         case ICMPV6_TIME_EXCEED:
1096                 *err = EHOSTUNREACH;
1097                 break;
1098         }
1099 
1100         return fatal;
1101 }
1102 EXPORT_SYMBOL(icmpv6_err_convert);
1103 
1104 #ifdef CONFIG_SYSCTL
1105 static struct ctl_table ipv6_icmp_table_template[] = {
1106         {
1107                 .procname       = "ratelimit",
1108                 .data           = &init_net.ipv6.sysctl.icmpv6_time,
1109                 .maxlen         = sizeof(int),
1110                 .mode           = 0644,
1111                 .proc_handler   = proc_dointvec_ms_jiffies,
1112         },
1113         { },
1114 };
1115 
1116 struct ctl_table * __net_init ipv6_icmp_sysctl_init(struct net *net)
1117 {
1118         struct ctl_table *table;
1119 
1120         table = kmemdup(ipv6_icmp_table_template,
1121                         sizeof(ipv6_icmp_table_template),
1122                         GFP_KERNEL);
1123 
1124         if (table)
1125                 table[0].data = &net->ipv6.sysctl.icmpv6_time;
1126 
1127         return table;
1128 }
1129 #endif
1130 

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