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 * A packet received on an interface with a destination address 126 * of loopback must be dropped. 127 */ 128 if (!(dev->flags & IFF_LOOPBACK) && 129 ipv6_addr_loopback(&hdr->daddr)) 130 goto err; 131 132 /* RFC4291 Errata ID: 3480 133 * Interface-Local scope spans only a single interface on a 134 * node and is useful only for loopback transmission of 135 * multicast. Packets with interface-local scope received 136 * from another node must be discarded. 137 */ 138 if (!(skb->pkt_type == PACKET_LOOPBACK || 139 dev->flags & IFF_LOOPBACK) && 140 ipv6_addr_is_multicast(&hdr->daddr) && 141 IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 1) 142 goto err; 143 144 /* If enabled, drop unicast packets that were encapsulated in link-layer 145 * multicast or broadcast to protected against the so-called "hole-196" 146 * attack in 802.11 wireless. 147 */ 148 if (!ipv6_addr_is_multicast(&hdr->daddr) && 149 (skb->pkt_type == PACKET_BROADCAST || 150 skb->pkt_type == PACKET_MULTICAST) && 151 idev->cnf.drop_unicast_in_l2_multicast) 152 goto err; 153 154 /* RFC4291 2.7 155 * Nodes must not originate a packet to a multicast address whose scope 156 * field contains the reserved value 0; if such a packet is received, it 157 * must be silently dropped. 158 */ 159 if (ipv6_addr_is_multicast(&hdr->daddr) && 160 IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 0) 161 goto err; 162 163 /* 164 * RFC4291 2.7 165 * Multicast addresses must not be used as source addresses in IPv6 166 * packets or appear in any Routing header. 167 */ 168 if (ipv6_addr_is_multicast(&hdr->saddr)) 169 goto err; 170 171 skb->transport_header = skb->network_header + sizeof(*hdr); 172 IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr); 173 174 pkt_len = ntohs(hdr->payload_len); 175 176 /* pkt_len may be zero if Jumbo payload option is present */ 177 if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) { 178 if (pkt_len + sizeof(struct ipv6hdr) > skb->len) { 179 __IP6_INC_STATS(net, 180 idev, IPSTATS_MIB_INTRUNCATEDPKTS); 181 goto drop; 182 } 183 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) { 184 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS); 185 goto drop; 186 } 187 hdr = ipv6_hdr(skb); 188 } 189 190 if (hdr->nexthdr == NEXTHDR_HOP) { 191 if (ipv6_parse_hopopts(skb) < 0) { 192 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS); 193 rcu_read_unlock(); 194 return NET_RX_DROP; 195 } 196 } 197 198 rcu_read_unlock(); 199 200 /* Must drop socket now because of tproxy. */ 201 skb_orphan(skb); 202 203 return NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, 204 net, NULL, skb, dev, NULL, 205 ip6_rcv_finish); 206 err: 207 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS); 208 drop: 209 rcu_read_unlock(); 210 kfree_skb(skb); 211 return NET_RX_DROP; 212 } 213 214 /* 215 * Deliver the packet to the host 216 */ 217 218 219 static int ip6_input_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 220 { 221 const struct inet6_protocol *ipprot; 222 struct inet6_dev *idev; 223 unsigned int nhoff; 224 int nexthdr; 225 bool raw; 226 227 /* 228 * Parse extension headers 229 */ 230 231 rcu_read_lock(); 232 resubmit: 233 idev = ip6_dst_idev(skb_dst(skb)); 234 if (!pskb_pull(skb, skb_transport_offset(skb))) 235 goto discard; 236 nhoff = IP6CB(skb)->nhoff; 237 nexthdr = skb_network_header(skb)[nhoff]; 238 239 raw = raw6_local_deliver(skb, nexthdr); 240 ipprot = rcu_dereference(inet6_protos[nexthdr]); 241 if (ipprot) { 242 int ret; 243 244 if (ipprot->flags & INET6_PROTO_FINAL) { 245 const struct ipv6hdr *hdr; 246 247 /* Free reference early: we don't need it any more, 248 and it may hold ip_conntrack module loaded 249 indefinitely. */ 250 nf_reset(skb); 251 252 skb_postpull_rcsum(skb, skb_network_header(skb), 253 skb_network_header_len(skb)); 254 hdr = ipv6_hdr(skb); 255 if (ipv6_addr_is_multicast(&hdr->daddr) && 256 !ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, 257 &hdr->saddr) && 258 !ipv6_is_mld(skb, nexthdr, skb_network_header_len(skb))) 259 goto discard; 260 } 261 if (!(ipprot->flags & INET6_PROTO_NOPOLICY) && 262 !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) 263 goto discard; 264 265 ret = ipprot->handler(skb); 266 if (ret > 0) 267 goto resubmit; 268 else if (ret == 0) 269 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDELIVERS); 270 } else { 271 if (!raw) { 272 if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) { 273 __IP6_INC_STATS(net, idev, 274 IPSTATS_MIB_INUNKNOWNPROTOS); 275 icmpv6_send(skb, ICMPV6_PARAMPROB, 276 ICMPV6_UNK_NEXTHDR, nhoff); 277 } 278 kfree_skb(skb); 279 } else { 280 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDELIVERS); 281 consume_skb(skb); 282 } 283 } 284 rcu_read_unlock(); 285 return 0; 286 287 discard: 288 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDISCARDS); 289 rcu_read_unlock(); 290 kfree_skb(skb); 291 return 0; 292 } 293 294 295 int ip6_input(struct sk_buff *skb) 296 { 297 return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_IN, 298 dev_net(skb->dev), NULL, skb, skb->dev, NULL, 299 ip6_input_finish); 300 } 301 302 int ip6_mc_input(struct sk_buff *skb) 303 { 304 const struct ipv6hdr *hdr; 305 bool deliver; 306 307 __IP6_UPD_PO_STATS(dev_net(skb_dst(skb)->dev), 308 ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INMCAST, 309 skb->len); 310 311 hdr = ipv6_hdr(skb); 312 deliver = ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, NULL); 313 314 #ifdef CONFIG_IPV6_MROUTE 315 /* 316 * IPv6 multicast router mode is now supported ;) 317 */ 318 if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding && 319 !(ipv6_addr_type(&hdr->daddr) & 320 (IPV6_ADDR_LOOPBACK|IPV6_ADDR_LINKLOCAL)) && 321 likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) { 322 /* 323 * Okay, we try to forward - split and duplicate 324 * packets. 325 */ 326 struct sk_buff *skb2; 327 struct inet6_skb_parm *opt = IP6CB(skb); 328 329 /* Check for MLD */ 330 if (unlikely(opt->flags & IP6SKB_ROUTERALERT)) { 331 /* Check if this is a mld message */ 332 u8 nexthdr = hdr->nexthdr; 333 __be16 frag_off; 334 int offset; 335 336 /* Check if the value of Router Alert 337 * is for MLD (0x0000). 338 */ 339 if (opt->ra == htons(IPV6_OPT_ROUTERALERT_MLD)) { 340 deliver = false; 341 342 if (!ipv6_ext_hdr(nexthdr)) { 343 /* BUG */ 344 goto out; 345 } 346 offset = ipv6_skip_exthdr(skb, sizeof(*hdr), 347 &nexthdr, &frag_off); 348 if (offset < 0) 349 goto out; 350 351 if (ipv6_is_mld(skb, nexthdr, offset)) 352 deliver = true; 353 354 goto out; 355 } 356 /* unknown RA - process it normally */ 357 } 358 359 if (deliver) 360 skb2 = skb_clone(skb, GFP_ATOMIC); 361 else { 362 skb2 = skb; 363 skb = NULL; 364 } 365 366 if (skb2) { 367 ip6_mr_input(skb2); 368 } 369 } 370 out: 371 #endif 372 if (likely(deliver)) 373 ip6_input(skb); 374 else { 375 /* discard */ 376 kfree_skb(skb); 377 } 378 379 return 0; 380 } 381