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 33 #include <linux/netfilter.h> 34 #include <linux/netfilter_ipv6.h> 35 36 #include <net/sock.h> 37 #include <net/snmp.h> 38 39 #include <net/ipv6.h> 40 #include <net/protocol.h> 41 #include <net/transp_v6.h> 42 #include <net/rawv6.h> 43 #include <net/ndisc.h> 44 #include <net/ip6_route.h> 45 #include <net/addrconf.h> 46 #include <net/xfrm.h> 47 #include <net/inet_ecn.h> 48 #include <net/dst_metadata.h> 49 50 int ip6_rcv_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 51 { 52 /* if ingress device is enslaved to an L3 master device pass the 53 * skb to its handler for processing 54 */ 55 skb = l3mdev_ip6_rcv(skb); 56 if (!skb) 57 return NET_RX_SUCCESS; 58 59 if (net->ipv4.sysctl_ip_early_demux && !skb_dst(skb) && skb->sk == NULL) { 60 const struct inet6_protocol *ipprot; 61 62 ipprot = rcu_dereference(inet6_protos[ipv6_hdr(skb)->nexthdr]); 63 if (ipprot && ipprot->early_demux) 64 ipprot->early_demux(skb); 65 } 66 if (!skb_valid_dst(skb)) 67 ip6_route_input(skb); 68 69 return dst_input(skb); 70 } 71 72 int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev) 73 { 74 const struct ipv6hdr *hdr; 75 u32 pkt_len; 76 struct inet6_dev *idev; 77 struct net *net = dev_net(skb->dev); 78 79 if (skb->pkt_type == PACKET_OTHERHOST) { 80 kfree_skb(skb); 81 return NET_RX_DROP; 82 } 83 84 rcu_read_lock(); 85 86 idev = __in6_dev_get(skb->dev); 87 88 __IP6_UPD_PO_STATS(net, idev, IPSTATS_MIB_IN, skb->len); 89 90 if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL || 91 !idev || unlikely(idev->cnf.disable_ipv6)) { 92 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDISCARDS); 93 goto drop; 94 } 95 96 memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm)); 97 98 /* 99 * Store incoming device index. When the packet will 100 * be queued, we cannot refer to skb->dev anymore. 101 * 102 * BTW, when we send a packet for our own local address on a 103 * non-loopback interface (e.g. ethX), it is being delivered 104 * via the loopback interface (lo) here; skb->dev = loopback_dev. 105 * It, however, should be considered as if it is being 106 * arrived via the sending interface (ethX), because of the 107 * nature of scoping architecture. --yoshfuji 108 */ 109 IP6CB(skb)->iif = skb_valid_dst(skb) ? ip6_dst_idev(skb_dst(skb))->dev->ifindex : dev->ifindex; 110 111 if (unlikely(!pskb_may_pull(skb, sizeof(*hdr)))) 112 goto err; 113 114 hdr = ipv6_hdr(skb); 115 116 if (hdr->version != 6) 117 goto err; 118 119 __IP6_ADD_STATS(net, idev, 120 IPSTATS_MIB_NOECTPKTS + 121 (ipv6_get_dsfield(hdr) & INET_ECN_MASK), 122 max_t(unsigned short, 1, skb_shinfo(skb)->gso_segs)); 123 /* 124 * RFC4291 2.5.3 125 * The loopback address must not be used as the source address in IPv6 126 * packets that are sent outside of a single node. [..] 127 * A packet received on an interface with a destination address 128 * of loopback must be dropped. 129 */ 130 if ((ipv6_addr_loopback(&hdr->saddr) || 131 ipv6_addr_loopback(&hdr->daddr)) && 132 !(dev->flags & IFF_LOOPBACK)) 133 goto err; 134 135 /* RFC4291 Errata ID: 3480 136 * Interface-Local scope spans only a single interface on a 137 * node and is useful only for loopback transmission of 138 * multicast. Packets with interface-local scope received 139 * from another node must be discarded. 140 */ 141 if (!(skb->pkt_type == PACKET_LOOPBACK || 142 dev->flags & IFF_LOOPBACK) && 143 ipv6_addr_is_multicast(&hdr->daddr) && 144 IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 1) 145 goto err; 146 147 /* If enabled, drop unicast packets that were encapsulated in link-layer 148 * multicast or broadcast to protected against the so-called "hole-196" 149 * attack in 802.11 wireless. 150 */ 151 if (!ipv6_addr_is_multicast(&hdr->daddr) && 152 (skb->pkt_type == PACKET_BROADCAST || 153 skb->pkt_type == PACKET_MULTICAST) && 154 idev->cnf.drop_unicast_in_l2_multicast) 155 goto err; 156 157 /* RFC4291 2.7 158 * Nodes must not originate a packet to a multicast address whose scope 159 * field contains the reserved value 0; if such a packet is received, it 160 * must be silently dropped. 161 */ 162 if (ipv6_addr_is_multicast(&hdr->daddr) && 163 IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 0) 164 goto err; 165 166 /* 167 * RFC4291 2.7 168 * Multicast addresses must not be used as source addresses in IPv6 169 * packets or appear in any Routing header. 170 */ 171 if (ipv6_addr_is_multicast(&hdr->saddr)) 172 goto err; 173 174 skb->transport_header = skb->network_header + sizeof(*hdr); 175 IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr); 176 177 pkt_len = ntohs(hdr->payload_len); 178 179 /* pkt_len may be zero if Jumbo payload option is present */ 180 if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) { 181 if (pkt_len + sizeof(struct ipv6hdr) > skb->len) { 182 __IP6_INC_STATS(net, 183 idev, IPSTATS_MIB_INTRUNCATEDPKTS); 184 goto drop; 185 } 186 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) { 187 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS); 188 goto drop; 189 } 190 hdr = ipv6_hdr(skb); 191 } 192 193 if (hdr->nexthdr == NEXTHDR_HOP) { 194 if (ipv6_parse_hopopts(skb) < 0) { 195 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS); 196 rcu_read_unlock(); 197 return NET_RX_DROP; 198 } 199 } 200 201 rcu_read_unlock(); 202 203 /* Must drop socket now because of tproxy. */ 204 skb_orphan(skb); 205 206 return NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, 207 net, NULL, skb, dev, NULL, 208 ip6_rcv_finish); 209 err: 210 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS); 211 drop: 212 rcu_read_unlock(); 213 kfree_skb(skb); 214 return NET_RX_DROP; 215 } 216 217 /* 218 * Deliver the packet to the host 219 */ 220 221 222 static int ip6_input_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 223 { 224 const struct inet6_protocol *ipprot; 225 struct inet6_dev *idev; 226 unsigned int nhoff; 227 int nexthdr; 228 bool raw; 229 bool have_final = false; 230 231 /* 232 * Parse extension headers 233 */ 234 235 rcu_read_lock(); 236 resubmit: 237 idev = ip6_dst_idev(skb_dst(skb)); 238 if (!pskb_pull(skb, skb_transport_offset(skb))) 239 goto discard; 240 nhoff = IP6CB(skb)->nhoff; 241 nexthdr = skb_network_header(skb)[nhoff]; 242 243 resubmit_final: 244 raw = raw6_local_deliver(skb, nexthdr); 245 ipprot = rcu_dereference(inet6_protos[nexthdr]); 246 if (ipprot) { 247 int ret; 248 249 if (have_final) { 250 if (!(ipprot->flags & INET6_PROTO_FINAL)) { 251 /* Once we've seen a final protocol don't 252 * allow encapsulation on any non-final 253 * ones. This allows foo in UDP encapsulation 254 * to work. 255 */ 256 goto discard; 257 } 258 } else if (ipprot->flags & INET6_PROTO_FINAL) { 259 const struct ipv6hdr *hdr; 260 261 /* Only do this once for first final protocol */ 262 have_final = true; 263 264 /* Free reference early: we don't need it any more, 265 and it may hold ip_conntrack module loaded 266 indefinitely. */ 267 nf_reset(skb); 268 269 skb_postpull_rcsum(skb, skb_network_header(skb), 270 skb_network_header_len(skb)); 271 hdr = ipv6_hdr(skb); 272 if (ipv6_addr_is_multicast(&hdr->daddr) && 273 !ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, 274 &hdr->saddr) && 275 !ipv6_is_mld(skb, nexthdr, skb_network_header_len(skb))) 276 goto discard; 277 } 278 if (!(ipprot->flags & INET6_PROTO_NOPOLICY) && 279 !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) 280 goto discard; 281 282 ret = ipprot->handler(skb); 283 if (ret > 0) { 284 if (ipprot->flags & INET6_PROTO_FINAL) { 285 /* Not an extension header, most likely UDP 286 * encapsulation. Use return value as nexthdr 287 * protocol not nhoff (which presumably is 288 * not set by handler). 289 */ 290 nexthdr = ret; 291 goto resubmit_final; 292 } else { 293 goto resubmit; 294 } 295 } else if (ret == 0) { 296 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDELIVERS); 297 } 298 } else { 299 if (!raw) { 300 if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) { 301 __IP6_INC_STATS(net, idev, 302 IPSTATS_MIB_INUNKNOWNPROTOS); 303 icmpv6_send(skb, ICMPV6_PARAMPROB, 304 ICMPV6_UNK_NEXTHDR, nhoff); 305 } 306 kfree_skb(skb); 307 } else { 308 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDELIVERS); 309 consume_skb(skb); 310 } 311 } 312 rcu_read_unlock(); 313 return 0; 314 315 discard: 316 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDISCARDS); 317 rcu_read_unlock(); 318 kfree_skb(skb); 319 return 0; 320 } 321 322 323 int ip6_input(struct sk_buff *skb) 324 { 325 return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_IN, 326 dev_net(skb->dev), NULL, skb, skb->dev, NULL, 327 ip6_input_finish); 328 } 329 EXPORT_SYMBOL_GPL(ip6_input); 330 331 int ip6_mc_input(struct sk_buff *skb) 332 { 333 const struct ipv6hdr *hdr; 334 bool deliver; 335 336 __IP6_UPD_PO_STATS(dev_net(skb_dst(skb)->dev), 337 ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INMCAST, 338 skb->len); 339 340 hdr = ipv6_hdr(skb); 341 deliver = ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, NULL); 342 343 #ifdef CONFIG_IPV6_MROUTE 344 /* 345 * IPv6 multicast router mode is now supported ;) 346 */ 347 if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding && 348 !(ipv6_addr_type(&hdr->daddr) & 349 (IPV6_ADDR_LOOPBACK|IPV6_ADDR_LINKLOCAL)) && 350 likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) { 351 /* 352 * Okay, we try to forward - split and duplicate 353 * packets. 354 */ 355 struct sk_buff *skb2; 356 struct inet6_skb_parm *opt = IP6CB(skb); 357 358 /* Check for MLD */ 359 if (unlikely(opt->flags & IP6SKB_ROUTERALERT)) { 360 /* Check if this is a mld message */ 361 u8 nexthdr = hdr->nexthdr; 362 __be16 frag_off; 363 int offset; 364 365 /* Check if the value of Router Alert 366 * is for MLD (0x0000). 367 */ 368 if (opt->ra == htons(IPV6_OPT_ROUTERALERT_MLD)) { 369 deliver = false; 370 371 if (!ipv6_ext_hdr(nexthdr)) { 372 /* BUG */ 373 goto out; 374 } 375 offset = ipv6_skip_exthdr(skb, sizeof(*hdr), 376 &nexthdr, &frag_off); 377 if (offset < 0) 378 goto out; 379 380 if (ipv6_is_mld(skb, nexthdr, offset)) 381 deliver = true; 382 383 goto out; 384 } 385 /* unknown RA - process it normally */ 386 } 387 388 if (deliver) 389 skb2 = skb_clone(skb, GFP_ATOMIC); 390 else { 391 skb2 = skb; 392 skb = NULL; 393 } 394 395 if (skb2) { 396 ip6_mr_input(skb2); 397 } 398 } 399 out: 400 #endif 401 if (likely(deliver)) 402 ip6_input(skb); 403 else { 404 /* discard */ 405 kfree_skb(skb); 406 } 407 408 return 0; 409 } 410