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