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