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 skb->transport_header = skb->network_header + sizeof(*hdr); 227 IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr); 228 229 pkt_len = ntohs(hdr->payload_len); 230 231 /* pkt_len may be zero if Jumbo payload option is present */ 232 if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) { 233 if (pkt_len + sizeof(struct ipv6hdr) > skb->len) { 234 __IP6_INC_STATS(net, 235 idev, IPSTATS_MIB_INTRUNCATEDPKTS); 236 goto drop; 237 } 238 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) { 239 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS); 240 goto drop; 241 } 242 hdr = ipv6_hdr(skb); 243 } 244 245 if (hdr->nexthdr == NEXTHDR_HOP) { 246 if (ipv6_parse_hopopts(skb) < 0) { 247 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS); 248 rcu_read_unlock(); 249 return NULL; 250 } 251 } 252 253 rcu_read_unlock(); 254 255 /* Must drop socket now because of tproxy. */ 256 skb_orphan(skb); 257 258 return skb; 259 err: 260 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS); 261 drop: 262 rcu_read_unlock(); 263 kfree_skb(skb); 264 return NULL; 265 } 266 267 int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev) 268 { 269 struct net *net = dev_net(skb->dev); 270 271 skb = ip6_rcv_core(skb, dev, net); 272 if (skb == NULL) 273 return NET_RX_DROP; 274 return NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, 275 net, NULL, skb, dev, NULL, 276 ip6_rcv_finish); 277 } 278 279 static void ip6_sublist_rcv(struct list_head *head, struct net_device *dev, 280 struct net *net) 281 { 282 NF_HOOK_LIST(NFPROTO_IPV6, NF_INET_PRE_ROUTING, net, NULL, 283 head, dev, NULL, ip6_rcv_finish); 284 ip6_list_rcv_finish(net, NULL, head); 285 } 286 287 /* Receive a list of IPv6 packets */ 288 void ipv6_list_rcv(struct list_head *head, struct packet_type *pt, 289 struct net_device *orig_dev) 290 { 291 struct net_device *curr_dev = NULL; 292 struct net *curr_net = NULL; 293 struct sk_buff *skb, *next; 294 struct list_head sublist; 295 296 INIT_LIST_HEAD(&sublist); 297 list_for_each_entry_safe(skb, next, head, list) { 298 struct net_device *dev = skb->dev; 299 struct net *net = dev_net(dev); 300 301 skb_list_del_init(skb); 302 skb = ip6_rcv_core(skb, dev, net); 303 if (skb == NULL) 304 continue; 305 306 if (curr_dev != dev || curr_net != net) { 307 /* dispatch old sublist */ 308 if (!list_empty(&sublist)) 309 ip6_sublist_rcv(&sublist, curr_dev, curr_net); 310 /* start new sublist */ 311 INIT_LIST_HEAD(&sublist); 312 curr_dev = dev; 313 curr_net = net; 314 } 315 list_add_tail(&skb->list, &sublist); 316 } 317 /* dispatch final sublist */ 318 ip6_sublist_rcv(&sublist, curr_dev, curr_net); 319 } 320 321 INDIRECT_CALLABLE_DECLARE(int udpv6_rcv(struct sk_buff *)); 322 INDIRECT_CALLABLE_DECLARE(int tcp_v6_rcv(struct sk_buff *)); 323 324 /* 325 * Deliver the packet to the host 326 */ 327 void ip6_protocol_deliver_rcu(struct net *net, struct sk_buff *skb, int nexthdr, 328 bool have_final) 329 { 330 const struct inet6_protocol *ipprot; 331 struct inet6_dev *idev; 332 unsigned int nhoff; 333 bool raw; 334 335 /* 336 * Parse extension headers 337 */ 338 339 resubmit: 340 idev = ip6_dst_idev(skb_dst(skb)); 341 nhoff = IP6CB(skb)->nhoff; 342 if (!have_final) { 343 if (!pskb_pull(skb, skb_transport_offset(skb))) 344 goto discard; 345 nexthdr = skb_network_header(skb)[nhoff]; 346 } 347 348 resubmit_final: 349 raw = raw6_local_deliver(skb, nexthdr); 350 ipprot = rcu_dereference(inet6_protos[nexthdr]); 351 if (ipprot) { 352 int ret; 353 354 if (have_final) { 355 if (!(ipprot->flags & INET6_PROTO_FINAL)) { 356 /* Once we've seen a final protocol don't 357 * allow encapsulation on any non-final 358 * ones. This allows foo in UDP encapsulation 359 * to work. 360 */ 361 goto discard; 362 } 363 } else if (ipprot->flags & INET6_PROTO_FINAL) { 364 const struct ipv6hdr *hdr; 365 int sdif = inet6_sdif(skb); 366 struct net_device *dev; 367 368 /* Only do this once for first final protocol */ 369 have_final = true; 370 371 /* Free reference early: we don't need it any more, 372 and it may hold ip_conntrack module loaded 373 indefinitely. */ 374 nf_reset(skb); 375 376 skb_postpull_rcsum(skb, skb_network_header(skb), 377 skb_network_header_len(skb)); 378 hdr = ipv6_hdr(skb); 379 380 /* skb->dev passed may be master dev for vrfs. */ 381 if (sdif) { 382 dev = dev_get_by_index_rcu(net, sdif); 383 if (!dev) 384 goto discard; 385 } else { 386 dev = skb->dev; 387 } 388 389 if (ipv6_addr_is_multicast(&hdr->daddr) && 390 !ipv6_chk_mcast_addr(dev, &hdr->daddr, 391 &hdr->saddr) && 392 !ipv6_is_mld(skb, nexthdr, skb_network_header_len(skb))) 393 goto discard; 394 } 395 if (!(ipprot->flags & INET6_PROTO_NOPOLICY) && 396 !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) 397 goto discard; 398 399 ret = INDIRECT_CALL_2(ipprot->handler, tcp_v6_rcv, udpv6_rcv, 400 skb); 401 if (ret > 0) { 402 if (ipprot->flags & INET6_PROTO_FINAL) { 403 /* Not an extension header, most likely UDP 404 * encapsulation. Use return value as nexthdr 405 * protocol not nhoff (which presumably is 406 * not set by handler). 407 */ 408 nexthdr = ret; 409 goto resubmit_final; 410 } else { 411 goto resubmit; 412 } 413 } else if (ret == 0) { 414 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDELIVERS); 415 } 416 } else { 417 if (!raw) { 418 if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) { 419 __IP6_INC_STATS(net, idev, 420 IPSTATS_MIB_INUNKNOWNPROTOS); 421 icmpv6_send(skb, ICMPV6_PARAMPROB, 422 ICMPV6_UNK_NEXTHDR, nhoff); 423 } 424 kfree_skb(skb); 425 } else { 426 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDELIVERS); 427 consume_skb(skb); 428 } 429 } 430 return; 431 432 discard: 433 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDISCARDS); 434 kfree_skb(skb); 435 } 436 437 static int ip6_input_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 438 { 439 rcu_read_lock(); 440 ip6_protocol_deliver_rcu(net, skb, 0, false); 441 rcu_read_unlock(); 442 443 return 0; 444 } 445 446 447 int ip6_input(struct sk_buff *skb) 448 { 449 return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_IN, 450 dev_net(skb->dev), NULL, skb, skb->dev, NULL, 451 ip6_input_finish); 452 } 453 EXPORT_SYMBOL_GPL(ip6_input); 454 455 int ip6_mc_input(struct sk_buff *skb) 456 { 457 int sdif = inet6_sdif(skb); 458 const struct ipv6hdr *hdr; 459 struct net_device *dev; 460 bool deliver; 461 462 __IP6_UPD_PO_STATS(dev_net(skb_dst(skb)->dev), 463 __in6_dev_get_safely(skb->dev), IPSTATS_MIB_INMCAST, 464 skb->len); 465 466 /* skb->dev passed may be master dev for vrfs. */ 467 if (sdif) { 468 rcu_read_lock(); 469 dev = dev_get_by_index_rcu(dev_net(skb->dev), sdif); 470 if (!dev) { 471 rcu_read_unlock(); 472 kfree_skb(skb); 473 return -ENODEV; 474 } 475 } else { 476 dev = skb->dev; 477 } 478 479 hdr = ipv6_hdr(skb); 480 deliver = ipv6_chk_mcast_addr(dev, &hdr->daddr, NULL); 481 if (sdif) 482 rcu_read_unlock(); 483 484 #ifdef CONFIG_IPV6_MROUTE 485 /* 486 * IPv6 multicast router mode is now supported ;) 487 */ 488 if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding && 489 !(ipv6_addr_type(&hdr->daddr) & 490 (IPV6_ADDR_LOOPBACK|IPV6_ADDR_LINKLOCAL)) && 491 likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) { 492 /* 493 * Okay, we try to forward - split and duplicate 494 * packets. 495 */ 496 struct sk_buff *skb2; 497 struct inet6_skb_parm *opt = IP6CB(skb); 498 499 /* Check for MLD */ 500 if (unlikely(opt->flags & IP6SKB_ROUTERALERT)) { 501 /* Check if this is a mld message */ 502 u8 nexthdr = hdr->nexthdr; 503 __be16 frag_off; 504 int offset; 505 506 /* Check if the value of Router Alert 507 * is for MLD (0x0000). 508 */ 509 if (opt->ra == htons(IPV6_OPT_ROUTERALERT_MLD)) { 510 deliver = false; 511 512 if (!ipv6_ext_hdr(nexthdr)) { 513 /* BUG */ 514 goto out; 515 } 516 offset = ipv6_skip_exthdr(skb, sizeof(*hdr), 517 &nexthdr, &frag_off); 518 if (offset < 0) 519 goto out; 520 521 if (ipv6_is_mld(skb, nexthdr, offset)) 522 deliver = true; 523 524 goto out; 525 } 526 /* unknown RA - process it normally */ 527 } 528 529 if (deliver) 530 skb2 = skb_clone(skb, GFP_ATOMIC); 531 else { 532 skb2 = skb; 533 skb = NULL; 534 } 535 536 if (skb2) { 537 ip6_mr_input(skb2); 538 } 539 } 540 out: 541 #endif 542 if (likely(deliver)) 543 ip6_input(skb); 544 else { 545 /* discard */ 546 kfree_skb(skb); 547 } 548 549 return 0; 550 } 551