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 ip6_sublist_rcv(&sublist, curr_dev, curr_net); 329 } 330 331 INDIRECT_CALLABLE_DECLARE(int udpv6_rcv(struct sk_buff *)); 332 INDIRECT_CALLABLE_DECLARE(int tcp_v6_rcv(struct sk_buff *)); 333 334 /* 335 * Deliver the packet to the host 336 */ 337 void ip6_protocol_deliver_rcu(struct net *net, struct sk_buff *skb, int nexthdr, 338 bool have_final) 339 { 340 const struct inet6_protocol *ipprot; 341 struct inet6_dev *idev; 342 unsigned int nhoff; 343 bool raw; 344 345 /* 346 * Parse extension headers 347 */ 348 349 resubmit: 350 idev = ip6_dst_idev(skb_dst(skb)); 351 nhoff = IP6CB(skb)->nhoff; 352 if (!have_final) { 353 if (!pskb_pull(skb, skb_transport_offset(skb))) 354 goto discard; 355 nexthdr = skb_network_header(skb)[nhoff]; 356 } 357 358 resubmit_final: 359 raw = raw6_local_deliver(skb, nexthdr); 360 ipprot = rcu_dereference(inet6_protos[nexthdr]); 361 if (ipprot) { 362 int ret; 363 364 if (have_final) { 365 if (!(ipprot->flags & INET6_PROTO_FINAL)) { 366 /* Once we've seen a final protocol don't 367 * allow encapsulation on any non-final 368 * ones. This allows foo in UDP encapsulation 369 * to work. 370 */ 371 goto discard; 372 } 373 } else if (ipprot->flags & INET6_PROTO_FINAL) { 374 const struct ipv6hdr *hdr; 375 int sdif = inet6_sdif(skb); 376 struct net_device *dev; 377 378 /* Only do this once for first final protocol */ 379 have_final = true; 380 381 /* Free reference early: we don't need it any more, 382 and it may hold ip_conntrack module loaded 383 indefinitely. */ 384 nf_reset_ct(skb); 385 386 skb_postpull_rcsum(skb, skb_network_header(skb), 387 skb_network_header_len(skb)); 388 hdr = ipv6_hdr(skb); 389 390 /* skb->dev passed may be master dev for vrfs. */ 391 if (sdif) { 392 dev = dev_get_by_index_rcu(net, sdif); 393 if (!dev) 394 goto discard; 395 } else { 396 dev = skb->dev; 397 } 398 399 if (ipv6_addr_is_multicast(&hdr->daddr) && 400 !ipv6_chk_mcast_addr(dev, &hdr->daddr, 401 &hdr->saddr) && 402 !ipv6_is_mld(skb, nexthdr, skb_network_header_len(skb))) 403 goto discard; 404 } 405 if (!(ipprot->flags & INET6_PROTO_NOPOLICY) && 406 !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) 407 goto discard; 408 409 ret = INDIRECT_CALL_2(ipprot->handler, tcp_v6_rcv, udpv6_rcv, 410 skb); 411 if (ret > 0) { 412 if (ipprot->flags & INET6_PROTO_FINAL) { 413 /* Not an extension header, most likely UDP 414 * encapsulation. Use return value as nexthdr 415 * protocol not nhoff (which presumably is 416 * not set by handler). 417 */ 418 nexthdr = ret; 419 goto resubmit_final; 420 } else { 421 goto resubmit; 422 } 423 } else if (ret == 0) { 424 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDELIVERS); 425 } 426 } else { 427 if (!raw) { 428 if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) { 429 __IP6_INC_STATS(net, idev, 430 IPSTATS_MIB_INUNKNOWNPROTOS); 431 icmpv6_send(skb, ICMPV6_PARAMPROB, 432 ICMPV6_UNK_NEXTHDR, nhoff); 433 } 434 kfree_skb(skb); 435 } else { 436 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDELIVERS); 437 consume_skb(skb); 438 } 439 } 440 return; 441 442 discard: 443 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDISCARDS); 444 kfree_skb(skb); 445 } 446 447 static int ip6_input_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 448 { 449 rcu_read_lock(); 450 ip6_protocol_deliver_rcu(net, skb, 0, false); 451 rcu_read_unlock(); 452 453 return 0; 454 } 455 456 457 int ip6_input(struct sk_buff *skb) 458 { 459 return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_IN, 460 dev_net(skb->dev), NULL, skb, skb->dev, NULL, 461 ip6_input_finish); 462 } 463 EXPORT_SYMBOL_GPL(ip6_input); 464 465 int ip6_mc_input(struct sk_buff *skb) 466 { 467 int sdif = inet6_sdif(skb); 468 const struct ipv6hdr *hdr; 469 struct net_device *dev; 470 bool deliver; 471 472 __IP6_UPD_PO_STATS(dev_net(skb_dst(skb)->dev), 473 __in6_dev_get_safely(skb->dev), IPSTATS_MIB_INMCAST, 474 skb->len); 475 476 /* skb->dev passed may be master dev for vrfs. */ 477 if (sdif) { 478 rcu_read_lock(); 479 dev = dev_get_by_index_rcu(dev_net(skb->dev), sdif); 480 if (!dev) { 481 rcu_read_unlock(); 482 kfree_skb(skb); 483 return -ENODEV; 484 } 485 } else { 486 dev = skb->dev; 487 } 488 489 hdr = ipv6_hdr(skb); 490 deliver = ipv6_chk_mcast_addr(dev, &hdr->daddr, NULL); 491 if (sdif) 492 rcu_read_unlock(); 493 494 #ifdef CONFIG_IPV6_MROUTE 495 /* 496 * IPv6 multicast router mode is now supported ;) 497 */ 498 if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding && 499 !(ipv6_addr_type(&hdr->daddr) & 500 (IPV6_ADDR_LOOPBACK|IPV6_ADDR_LINKLOCAL)) && 501 likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) { 502 /* 503 * Okay, we try to forward - split and duplicate 504 * packets. 505 */ 506 struct sk_buff *skb2; 507 struct inet6_skb_parm *opt = IP6CB(skb); 508 509 /* Check for MLD */ 510 if (unlikely(opt->flags & IP6SKB_ROUTERALERT)) { 511 /* Check if this is a mld message */ 512 u8 nexthdr = hdr->nexthdr; 513 __be16 frag_off; 514 int offset; 515 516 /* Check if the value of Router Alert 517 * is for MLD (0x0000). 518 */ 519 if (opt->ra == htons(IPV6_OPT_ROUTERALERT_MLD)) { 520 deliver = false; 521 522 if (!ipv6_ext_hdr(nexthdr)) { 523 /* BUG */ 524 goto out; 525 } 526 offset = ipv6_skip_exthdr(skb, sizeof(*hdr), 527 &nexthdr, &frag_off); 528 if (offset < 0) 529 goto out; 530 531 if (ipv6_is_mld(skb, nexthdr, offset)) 532 deliver = true; 533 534 goto out; 535 } 536 /* unknown RA - process it normally */ 537 } 538 539 if (deliver) 540 skb2 = skb_clone(skb, GFP_ATOMIC); 541 else { 542 skb2 = skb; 543 skb = NULL; 544 } 545 546 if (skb2) { 547 ip6_mr_input(skb2); 548 } 549 } 550 out: 551 #endif 552 if (likely(deliver)) 553 ip6_input(skb); 554 else { 555 /* discard */ 556 kfree_skb(skb); 557 } 558 559 return 0; 560 } 561