net/ipv6/ip6_input.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *      IPv6 input
   4  *      Linux INET6 implementation
   5  *
   6  *      Authors:
   7  *      Pedro Roque             <roque@di.fc.ul.pt>
   8  *      Ian P. Morris           <I.P.Morris@soton.ac.uk>
   9  *
  10  *      Based in linux/net/ipv4/ip_input.c
  11  */
  12 /* Changes
  13  *
  14  *      Mitsuru KANDA @USAGI and
  15  *      YOSHIFUJI Hideaki @USAGI: Remove ipv6_parse_exthdrs().
  16  */
  17
  18 #include <linux/errno.h>
  19 #include <linux/types.h>
  20 #include <linux/socket.h>
  21 #include <linux/sockios.h>
  22 #include <linux/net.h>
  23 #include <linux/netdevice.h>
  24 #include <linux/in6.h>
  25 #include <linux/icmpv6.h>
  26 #include <linux/mroute6.h>
  27 #include <linux/slab.h>
  28 #include <linux/indirect_call_wrapper.h>
  29
  30 #include <linux/netfilter.h>
  31 #include <linux/netfilter_ipv6.h>
  32
  33 #include <net/sock.h>
  34 #include <net/snmp.h>
  35
  36 #include <net/ipv6.h>
  37 #include <net/protocol.h>
  38 #include <net/transp_v6.h>
  39 #include <net/rawv6.h>
  40 #include <net/ndisc.h>
  41 #include <net/ip6_route.h>
  42 #include <net/addrconf.h>
  43 #include <net/xfrm.h>
  44 #include <net/inet_ecn.h>
  45 #include <net/dst_metadata.h>
  46
  47 INDIRECT_CALLABLE_DECLARE(void udp_v6_early_demux(struct sk_buff *));
  48 INDIRECT_CALLABLE_DECLARE(void tcp_v6_early_demux(struct sk_buff *));
  49 static void ip6_rcv_finish_core(struct net *net, struct sock *sk,
  50                                 struct sk_buff *skb)
  51 {
  52         void (*edemux)(struct sk_buff *skb);
  53
  54         if (net->ipv4.sysctl_ip_early_demux && !skb_dst(skb) && skb->sk == NULL) {
  55                 const struct inet6_protocol *ipprot;
  56
  57                 ipprot = rcu_dereference(inet6_protos[ipv6_hdr(skb)->nexthdr]);
  58                 if (ipprot && (edemux = READ_ONCE(ipprot->early_demux)))
  59                         INDIRECT_CALL_2(edemux, tcp_v6_early_demux,
  60                                         udp_v6_early_demux, skb);
  61         }
  62         if (!skb_valid_dst(skb))
  63                 ip6_route_input(skb);
  64 }
  65
  66 int ip6_rcv_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
  67 {
  68         /* if ingress device is enslaved to an L3 master device pass the
  69          * skb to its handler for processing
  70          */
  71         skb = l3mdev_ip6_rcv(skb);
  72         if (!skb)
  73                 return NET_RX_SUCCESS;
  74         ip6_rcv_finish_core(net, sk, skb);
  75
  76         return dst_input(skb);
  77 }
  78
  79 static void ip6_sublist_rcv_finish(struct list_head *head)
  80 {
  81         struct sk_buff *skb, *next;
  82
  83         list_for_each_entry_safe(skb, next, head, list) {
  84                 skb_list_del_init(skb);
  85                 dst_input(skb);
  86         }
  87 }
  88
  89 static void ip6_list_rcv_finish(struct net *net, struct sock *sk,
  90                                 struct list_head *head)
  91 {
  92         struct dst_entry *curr_dst = NULL;
  93         struct sk_buff *skb, *next;
  94         struct list_head sublist;
  95
  96         INIT_LIST_HEAD(&sublist);
  97         list_for_each_entry_safe(skb, next, head, list) {
  98                 struct dst_entry *dst;
  99
 100                 skb_list_del_init(skb);
 101                 /* if ingress device is enslaved to an L3 master device pass the
 102                  * skb to its handler for processing
 103                  */
 104                 skb = l3mdev_ip6_rcv(skb);
 105                 if (!skb)
 106                         continue;
 107                 ip6_rcv_finish_core(net, sk, skb);
 108                 dst = skb_dst(skb);
 109                 if (curr_dst != dst) {
 110                         /* dispatch old sublist */
 111                         if (!list_empty(&sublist))
 112                                 ip6_sublist_rcv_finish(&sublist);
 113                         /* start new sublist */
 114                         INIT_LIST_HEAD(&sublist);
 115                         curr_dst = dst;
 116                 }
 117                 list_add_tail(&skb->list, &sublist);
 118         }
 119         /* dispatch final sublist */
 120         ip6_sublist_rcv_finish(&sublist);
 121 }
 122
 123 static struct sk_buff *ip6_rcv_core(struct sk_buff *skb, struct net_device *dev,
 124                                     struct net *net)
 125 {
 126         const struct ipv6hdr *hdr;
 127         u32 pkt_len;
 128         struct inet6_dev *idev;
 129
 130         if (skb->pkt_type == PACKET_OTHERHOST) {
 131                 kfree_skb(skb);
 132                 return NULL;
 133         }
 134
 135         rcu_read_lock();
 136
 137         idev = __in6_dev_get(skb->dev);
 138
 139         __IP6_UPD_PO_STATS(net, idev, IPSTATS_MIB_IN, skb->len);
 140
 141         if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL ||
 142             !idev || unlikely(idev->cnf.disable_ipv6)) {
 143                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDISCARDS);
 144                 goto drop;
 145         }
 146
 147         memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm));
 148
 149         /*
 150          * Store incoming device index. When the packet will
 151          * be queued, we cannot refer to skb->dev anymore.
 152          *
 153          * BTW, when we send a packet for our own local address on a
 154          * non-loopback interface (e.g. ethX), it is being delivered
 155          * via the loopback interface (lo) here; skb->dev = loopback_dev.
 156          * It, however, should be considered as if it is being
 157          * arrived via the sending interface (ethX), because of the
 158          * nature of scoping architecture. --yoshfuji
 159          */
 160         IP6CB(skb)->iif = skb_valid_dst(skb) ? ip6_dst_idev(skb_dst(skb))->dev->ifindex : dev->ifindex;
 161
 162         if (unlikely(!pskb_may_pull(skb, sizeof(*hdr))))
 163                 goto err;
 164
 165         hdr = ipv6_hdr(skb);
 166
 167         if (hdr->version != 6)
 168                 goto err;
 169
 170         __IP6_ADD_STATS(net, idev,
 171                         IPSTATS_MIB_NOECTPKTS +
 172                                 (ipv6_get_dsfield(hdr) & INET_ECN_MASK),
 173                         max_t(unsigned short, 1, skb_shinfo(skb)->gso_segs));
 174         /*
 175          * RFC4291 2.5.3
 176          * The loopback address must not be used as the source address in IPv6
 177          * packets that are sent outside of a single node. [..]
 178          * A packet received on an interface with a destination address
 179          * of loopback must be dropped.
 180          */
 181         if ((ipv6_addr_loopback(&hdr->saddr) ||
 182              ipv6_addr_loopback(&hdr->daddr)) &&
 183             !(dev->flags & IFF_LOOPBACK) &&
 184             !netif_is_l3_master(dev))
 185                 goto err;
 186
 187         /* RFC4291 Errata ID: 3480
 188          * Interface-Local scope spans only a single interface on a
 189          * node and is useful only for loopback transmission of
 190          * multicast.  Packets with interface-local scope received
 191          * from another node must be discarded.
 192          */
 193         if (!(skb->pkt_type == PACKET_LOOPBACK ||
 194               dev->flags & IFF_LOOPBACK) &&
 195             ipv6_addr_is_multicast(&hdr->daddr) &&
 196             IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 1)
 197                 goto err;
 198
 199         /* If enabled, drop unicast packets that were encapsulated in link-layer
 200          * multicast or broadcast to protected against the so-called "hole-196"
 201          * attack in 802.11 wireless.
 202          */
 203         if (!ipv6_addr_is_multicast(&hdr->daddr) &&
 204             (skb->pkt_type == PACKET_BROADCAST ||
 205              skb->pkt_type == PACKET_MULTICAST) &&
 206             idev->cnf.drop_unicast_in_l2_multicast)
 207                 goto err;
 208
 209         /* RFC4291 2.7
 210          * Nodes must not originate a packet to a multicast address whose scope
 211          * field contains the reserved value 0; if such a packet is received, it
 212          * must be silently dropped.
 213          */
 214         if (ipv6_addr_is_multicast(&hdr->daddr) &&
 215             IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 0)
 216                 goto err;
 217
 218         /*
 219          * RFC4291 2.7
 220          * Multicast addresses must not be used as source addresses in IPv6
 221          * packets or appear in any Routing header.
 222          */
 223         if (ipv6_addr_is_multicast(&hdr->saddr))
 224                 goto err;
 225
 226         /* While RFC4291 is not explicit about v4mapped addresses
 227          * in IPv6 headers, it seems clear linux dual-stack
 228          * model can not deal properly with these.
 229          * Security models could be fooled by ::ffff:127.0.0.1 for example.
 230          *
 231          * https://tools.ietf.org/html/draft-itojun-v6ops-v4mapped-harmful-02
 232          */
 233         if (ipv6_addr_v4mapped(&hdr->saddr))
 234                 goto err;
 235
 236         skb->transport_header = skb->network_header + sizeof(*hdr);
 237         IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
 238
 239         pkt_len = ntohs(hdr->payload_len);
 240
 241         /* pkt_len may be zero if Jumbo payload option is present */
 242         if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
 243                 if (pkt_len + sizeof(struct ipv6hdr) > skb->len) {
 244                         __IP6_INC_STATS(net,
 245                                         idev, IPSTATS_MIB_INTRUNCATEDPKTS);
 246                         goto drop;
 247                 }
 248                 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) {
 249                         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 250                         goto drop;
 251                 }
 252                 hdr = ipv6_hdr(skb);
 253         }
 254
 255         if (hdr->nexthdr == NEXTHDR_HOP) {
 256                 if (ipv6_parse_hopopts(skb) < 0) {
 257                         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 258                         rcu_read_unlock();
 259                         return NULL;
 260                 }
 261         }
 262
 263         rcu_read_unlock();
 264
 265         /* Must drop socket now because of tproxy. */
 266         skb_orphan(skb);
 267
 268         return skb;
 269 err:
 270         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 271 drop:
 272         rcu_read_unlock();
 273         kfree_skb(skb);
 274         return NULL;
 275 }
 276
 277 int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev)
 278 {
 279         struct net *net = dev_net(skb->dev);
 280
 281         skb = ip6_rcv_core(skb, dev, net);
 282         if (skb == NULL)
 283                 return NET_RX_DROP;
 284         return NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING,
 285                        net, NULL, skb, dev, NULL,
 286                        ip6_rcv_finish);
 287 }
 288
 289 static void ip6_sublist_rcv(struct list_head *head, struct net_device *dev,
 290                             struct net *net)
 291 {
 292         NF_HOOK_LIST(NFPROTO_IPV6, NF_INET_PRE_ROUTING, net, NULL,
 293                      head, dev, NULL, ip6_rcv_finish);
 294         ip6_list_rcv_finish(net, NULL, head);
 295 }
 296
 297 /* Receive a list of IPv6 packets */
 298 void ipv6_list_rcv(struct list_head *head, struct packet_type *pt,
 299                    struct net_device *orig_dev)
 300 {
 301         struct net_device *curr_dev = NULL;
 302         struct net *curr_net = NULL;
 303         struct sk_buff *skb, *next;
 304         struct list_head sublist;
 305
 306         INIT_LIST_HEAD(&sublist);
 307         list_for_each_entry_safe(skb, next, head, list) {
 308                 struct net_device *dev = skb->dev;
 309                 struct net *net = dev_net(dev);
 310
 311                 skb_list_del_init(skb);
 312                 skb = ip6_rcv_core(skb, dev, net);
 313                 if (skb == NULL)
 314                         continue;
 315
 316                 if (curr_dev != dev || curr_net != net) {
 317                         /* dispatch old sublist */
 318                         if (!list_empty(&sublist))
 319                                 ip6_sublist_rcv(&sublist, curr_dev, curr_net);
 320                         /* start new sublist */
 321                         INIT_LIST_HEAD(&sublist);
 322                         curr_dev = dev;
 323                         curr_net = net;
 324                 }
 325                 list_add_tail(&skb->list, &sublist);
 326         }
 327         /* dispatch final sublist */
 328         if (!list_empty(&sublist))
 329                 ip6_sublist_rcv(&sublist, curr_dev, curr_net);
 330 }
 331
 332 INDIRECT_CALLABLE_DECLARE(int udpv6_rcv(struct sk_buff *));
 333 INDIRECT_CALLABLE_DECLARE(int tcp_v6_rcv(struct sk_buff *));
 334
 335 /*
 336  *      Deliver the packet to the host
 337  */
 338 void ip6_protocol_deliver_rcu(struct net *net, struct sk_buff *skb, int nexthdr,
 339                               bool have_final)
 340 {
 341         const struct inet6_protocol *ipprot;
 342         struct inet6_dev *idev;
 343         unsigned int nhoff;
 344         bool raw;
 345
 346         /*
 347          *      Parse extension headers
 348          */
 349
 350 resubmit:
 351         idev = ip6_dst_idev(skb_dst(skb));
 352         nhoff = IP6CB(skb)->nhoff;
 353         if (!have_final) {
 354                 if (!pskb_pull(skb, skb_transport_offset(skb)))
 355                         goto discard;
 356                 nexthdr = skb_network_header(skb)[nhoff];
 357         }
 358
 359 resubmit_final:
 360         raw = raw6_local_deliver(skb, nexthdr);
 361         ipprot = rcu_dereference(inet6_protos[nexthdr]);
 362         if (ipprot) {
 363                 int ret;
 364
 365                 if (have_final) {
 366                         if (!(ipprot->flags & INET6_PROTO_FINAL)) {
 367                                 /* Once we've seen a final protocol don't
 368                                  * allow encapsulation on any non-final
 369                                  * ones. This allows foo in UDP encapsulation
 370                                  * to work.
 371                                  */
 372                                 goto discard;
 373                         }
 374                 } else if (ipprot->flags & INET6_PROTO_FINAL) {
 375                         const struct ipv6hdr *hdr;
 376                         int sdif = inet6_sdif(skb);
 377                         struct net_device *dev;
 378
 379                         /* Only do this once for first final protocol */
 380                         have_final = true;
 381
 382                         /* Free reference early: we don't need it any more,
 383                            and it may hold ip_conntrack module loaded
 384                            indefinitely. */
 385                         nf_reset_ct(skb);
 386
 387                         skb_postpull_rcsum(skb, skb_network_header(skb),
 388                                            skb_network_header_len(skb));
 389                         hdr = ipv6_hdr(skb);
 390
 391                         /* skb->dev passed may be master dev for vrfs. */
 392                         if (sdif) {
 393                                 dev = dev_get_by_index_rcu(net, sdif);
 394                                 if (!dev)
 395                                         goto discard;
 396                         } else {
 397                                 dev = skb->dev;
 398                         }
 399
 400                         if (ipv6_addr_is_multicast(&hdr->daddr) &&
 401                             !ipv6_chk_mcast_addr(dev, &hdr->daddr,
 402                                                  &hdr->saddr) &&
 403                             !ipv6_is_mld(skb, nexthdr, skb_network_header_len(skb)))
 404                                 goto discard;
 405                 }
 406                 if (!(ipprot->flags & INET6_PROTO_NOPOLICY) &&
 407                     !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
 408                         goto discard;
 409
 410                 ret = INDIRECT_CALL_2(ipprot->handler, tcp_v6_rcv, udpv6_rcv,
 411                                       skb);
 412                 if (ret > 0) {
 413                         if (ipprot->flags & INET6_PROTO_FINAL) {
 414                                 /* Not an extension header, most likely UDP
 415                                  * encapsulation. Use return value as nexthdr
 416                                  * protocol not nhoff (which presumably is
 417                                  * not set by handler).
 418                                  */
 419                                 nexthdr = ret;
 420                                 goto resubmit_final;
 421                         } else {
 422                                 goto resubmit;
 423                         }
 424                 } else if (ret == 0) {
 425                         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDELIVERS);
 426                 }
 427         } else {
 428                 if (!raw) {
 429                         if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
 430                                 __IP6_INC_STATS(net, idev,
 431                                                 IPSTATS_MIB_INUNKNOWNPROTOS);
 432                                 icmpv6_send(skb, ICMPV6_PARAMPROB,
 433                                             ICMPV6_UNK_NEXTHDR, nhoff);
 434                         }
 435                         kfree_skb(skb);
 436                 } else {
 437                         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDELIVERS);
 438                         consume_skb(skb);
 439                 }
 440         }
 441         return;
 442
 443 discard:
 444         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDISCARDS);
 445         kfree_skb(skb);
 446 }
 447
 448 static int ip6_input_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
 449 {
 450         rcu_read_lock();
 451         ip6_protocol_deliver_rcu(net, skb, 0, false);
 452         rcu_read_unlock();
 453
 454         return 0;
 455 }
 456
 457
 458 int ip6_input(struct sk_buff *skb)
 459 {
 460         return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_IN,
 461                        dev_net(skb->dev), NULL, skb, skb->dev, NULL,
 462                        ip6_input_finish);
 463 }
 464 EXPORT_SYMBOL_GPL(ip6_input);
 465
 466 int ip6_mc_input(struct sk_buff *skb)
 467 {
 468         int sdif = inet6_sdif(skb);
 469         const struct ipv6hdr *hdr;
 470         struct net_device *dev;
 471         bool deliver;
 472
 473         __IP6_UPD_PO_STATS(dev_net(skb_dst(skb)->dev),
 474                          __in6_dev_get_safely(skb->dev), IPSTATS_MIB_INMCAST,
 475                          skb->len);
 476
 477         /* skb->dev passed may be master dev for vrfs. */
 478         if (sdif) {
 479                 rcu_read_lock();
 480                 dev = dev_get_by_index_rcu(dev_net(skb->dev), sdif);
 481                 if (!dev) {
 482                         rcu_read_unlock();
 483                         kfree_skb(skb);
 484                         return -ENODEV;
 485                 }
 486         } else {
 487                 dev = skb->dev;
 488         }
 489
 490         hdr = ipv6_hdr(skb);
 491         deliver = ipv6_chk_mcast_addr(dev, &hdr->daddr, NULL);
 492         if (sdif)
 493                 rcu_read_unlock();
 494
 495 #ifdef CONFIG_IPV6_MROUTE
 496         /*
 497          *      IPv6 multicast router mode is now supported ;)
 498          */
 499         if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding &&
 500             !(ipv6_addr_type(&hdr->daddr) &
 501               (IPV6_ADDR_LOOPBACK|IPV6_ADDR_LINKLOCAL)) &&
 502             likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) {
 503                 /*
 504                  * Okay, we try to forward - split and duplicate
 505                  * packets.
 506                  */
 507                 struct sk_buff *skb2;
 508                 struct inet6_skb_parm *opt = IP6CB(skb);
 509
 510                 /* Check for MLD */
 511                 if (unlikely(opt->flags & IP6SKB_ROUTERALERT)) {
 512                         /* Check if this is a mld message */
 513                         u8 nexthdr = hdr->nexthdr;
 514                         __be16 frag_off;
 515                         int offset;
 516
 517                         /* Check if the value of Router Alert
 518                          * is for MLD (0x0000).
 519                          */
 520                         if (opt->ra == htons(IPV6_OPT_ROUTERALERT_MLD)) {
 521                                 deliver = false;
 522
 523                                 if (!ipv6_ext_hdr(nexthdr)) {
 524                                         /* BUG */
 525                                         goto out;
 526                                 }
 527                                 offset = ipv6_skip_exthdr(skb, sizeof(*hdr),
 528                                                           &nexthdr, &frag_off);
 529                                 if (offset < 0)
 530                                         goto out;
 531
 532                                 if (ipv6_is_mld(skb, nexthdr, offset))
 533                                         deliver = true;
 534
 535                                 goto out;
 536                         }
 537                         /* unknown RA - process it normally */
 538                 }
 539
 540                 if (deliver)
 541                         skb2 = skb_clone(skb, GFP_ATOMIC);
 542                 else {
 543                         skb2 = skb;
 544                         skb = NULL;
 545                 }
 546
 547                 if (skb2) {
 548                         ip6_mr_input(skb2);
 549                 }
 550         }
 551 out:
 552 #endif
 553         if (likely(deliver))
 554                 ip6_input(skb);
 555         else {
 556                 /* discard */
 557                 kfree_skb(skb);
 558         }
 559
 560         return 0;
 561 }