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 (sysctl_ip_early_demux && !skb_dst(skb) && skb->sk == NULL) { 53 const struct inet6_protocol *ipprot; 54 55 ipprot = rcu_dereference(inet6_protos[ipv6_hdr(skb)->nexthdr]); 56 if (ipprot && ipprot->early_demux) 57 ipprot->early_demux(skb); 58 } 59 if (!skb_valid_dst(skb)) 60 ip6_route_input(skb); 61 62 return dst_input(skb); 63 } 64 65 int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev) 66 { 67 const struct ipv6hdr *hdr; 68 u32 pkt_len; 69 struct inet6_dev *idev; 70 struct net *net = dev_net(skb->dev); 71 72 if (skb->pkt_type == PACKET_OTHERHOST) { 73 kfree_skb(skb); 74 return NET_RX_DROP; 75 } 76 77 rcu_read_lock(); 78 79 idev = __in6_dev_get(skb->dev); 80 81 IP6_UPD_PO_STATS_BH(net, idev, IPSTATS_MIB_IN, skb->len); 82 83 if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL || 84 !idev || unlikely(idev->cnf.disable_ipv6)) { 85 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS); 86 goto drop; 87 } 88 89 memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm)); 90 91 /* 92 * Store incoming device index. When the packet will 93 * be queued, we cannot refer to skb->dev anymore. 94 * 95 * BTW, when we send a packet for our own local address on a 96 * non-loopback interface (e.g. ethX), it is being delivered 97 * via the loopback interface (lo) here; skb->dev = loopback_dev. 98 * It, however, should be considered as if it is being 99 * arrived via the sending interface (ethX), because of the 100 * nature of scoping architecture. --yoshfuji 101 */ 102 IP6CB(skb)->iif = skb_valid_dst(skb) ? ip6_dst_idev(skb_dst(skb))->dev->ifindex : dev->ifindex; 103 104 if (unlikely(!pskb_may_pull(skb, sizeof(*hdr)))) 105 goto err; 106 107 hdr = ipv6_hdr(skb); 108 109 if (hdr->version != 6) 110 goto err; 111 112 IP6_ADD_STATS_BH(net, idev, 113 IPSTATS_MIB_NOECTPKTS + 114 (ipv6_get_dsfield(hdr) & INET_ECN_MASK), 115 max_t(unsigned short, 1, skb_shinfo(skb)->gso_segs)); 116 /* 117 * RFC4291 2.5.3 118 * A packet received on an interface with a destination address 119 * of loopback must be dropped. 120 */ 121 if (!(dev->flags & IFF_LOOPBACK) && 122 ipv6_addr_loopback(&hdr->daddr)) 123 goto err; 124 125 /* RFC4291 Errata ID: 3480 126 * Interface-Local scope spans only a single interface on a 127 * node and is useful only for loopback transmission of 128 * multicast. Packets with interface-local scope received 129 * from another node must be discarded. 130 */ 131 if (!(skb->pkt_type == PACKET_LOOPBACK || 132 dev->flags & IFF_LOOPBACK) && 133 ipv6_addr_is_multicast(&hdr->daddr) && 134 IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 1) 135 goto err; 136 137 /* RFC4291 2.7 138 * Nodes must not originate a packet to a multicast address whose scope 139 * field contains the reserved value 0; if such a packet is received, it 140 * must be silently dropped. 141 */ 142 if (ipv6_addr_is_multicast(&hdr->daddr) && 143 IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 0) 144 goto err; 145 146 /* 147 * RFC4291 2.7 148 * Multicast addresses must not be used as source addresses in IPv6 149 * packets or appear in any Routing header. 150 */ 151 if (ipv6_addr_is_multicast(&hdr->saddr)) 152 goto err; 153 154 skb->transport_header = skb->network_header + sizeof(*hdr); 155 IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr); 156 157 pkt_len = ntohs(hdr->payload_len); 158 159 /* pkt_len may be zero if Jumbo payload option is present */ 160 if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) { 161 if (pkt_len + sizeof(struct ipv6hdr) > skb->len) { 162 IP6_INC_STATS_BH(net, 163 idev, IPSTATS_MIB_INTRUNCATEDPKTS); 164 goto drop; 165 } 166 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) { 167 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS); 168 goto drop; 169 } 170 hdr = ipv6_hdr(skb); 171 } 172 173 if (hdr->nexthdr == NEXTHDR_HOP) { 174 if (ipv6_parse_hopopts(skb) < 0) { 175 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS); 176 rcu_read_unlock(); 177 return NET_RX_DROP; 178 } 179 } 180 181 rcu_read_unlock(); 182 183 /* Must drop socket now because of tproxy. */ 184 skb_orphan(skb); 185 186 return NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, 187 net, NULL, skb, dev, NULL, 188 ip6_rcv_finish); 189 err: 190 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS); 191 drop: 192 rcu_read_unlock(); 193 kfree_skb(skb); 194 return NET_RX_DROP; 195 } 196 197 /* 198 * Deliver the packet to the host 199 */ 200 201 202 static int ip6_input_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 203 { 204 const struct inet6_protocol *ipprot; 205 struct inet6_dev *idev; 206 unsigned int nhoff; 207 int nexthdr; 208 bool raw; 209 210 /* 211 * Parse extension headers 212 */ 213 214 rcu_read_lock(); 215 resubmit: 216 idev = ip6_dst_idev(skb_dst(skb)); 217 if (!pskb_pull(skb, skb_transport_offset(skb))) 218 goto discard; 219 nhoff = IP6CB(skb)->nhoff; 220 nexthdr = skb_network_header(skb)[nhoff]; 221 222 raw = raw6_local_deliver(skb, nexthdr); 223 ipprot = rcu_dereference(inet6_protos[nexthdr]); 224 if (ipprot) { 225 int ret; 226 227 if (ipprot->flags & INET6_PROTO_FINAL) { 228 const struct ipv6hdr *hdr; 229 230 /* Free reference early: we don't need it any more, 231 and it may hold ip_conntrack module loaded 232 indefinitely. */ 233 nf_reset(skb); 234 235 skb_postpull_rcsum(skb, skb_network_header(skb), 236 skb_network_header_len(skb)); 237 hdr = ipv6_hdr(skb); 238 if (ipv6_addr_is_multicast(&hdr->daddr) && 239 !ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, 240 &hdr->saddr) && 241 !ipv6_is_mld(skb, nexthdr, skb_network_header_len(skb))) 242 goto discard; 243 } 244 if (!(ipprot->flags & INET6_PROTO_NOPOLICY) && 245 !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) 246 goto discard; 247 248 ret = ipprot->handler(skb); 249 if (ret > 0) 250 goto resubmit; 251 else if (ret == 0) 252 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS); 253 } else { 254 if (!raw) { 255 if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) { 256 IP6_INC_STATS_BH(net, idev, 257 IPSTATS_MIB_INUNKNOWNPROTOS); 258 icmpv6_send(skb, ICMPV6_PARAMPROB, 259 ICMPV6_UNK_NEXTHDR, nhoff); 260 } 261 kfree_skb(skb); 262 } else { 263 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS); 264 consume_skb(skb); 265 } 266 } 267 rcu_read_unlock(); 268 return 0; 269 270 discard: 271 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS); 272 rcu_read_unlock(); 273 kfree_skb(skb); 274 return 0; 275 } 276 277 278 int ip6_input(struct sk_buff *skb) 279 { 280 return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_IN, 281 dev_net(skb->dev), NULL, skb, skb->dev, NULL, 282 ip6_input_finish); 283 } 284 285 int ip6_mc_input(struct sk_buff *skb) 286 { 287 const struct ipv6hdr *hdr; 288 bool deliver; 289 290 IP6_UPD_PO_STATS_BH(dev_net(skb_dst(skb)->dev), 291 ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INMCAST, 292 skb->len); 293 294 hdr = ipv6_hdr(skb); 295 deliver = ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, NULL); 296 297 #ifdef CONFIG_IPV6_MROUTE 298 /* 299 * IPv6 multicast router mode is now supported ;) 300 */ 301 if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding && 302 !(ipv6_addr_type(&hdr->daddr) & 303 (IPV6_ADDR_LOOPBACK|IPV6_ADDR_LINKLOCAL)) && 304 likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) { 305 /* 306 * Okay, we try to forward - split and duplicate 307 * packets. 308 */ 309 struct sk_buff *skb2; 310 struct inet6_skb_parm *opt = IP6CB(skb); 311 312 /* Check for MLD */ 313 if (unlikely(opt->flags & IP6SKB_ROUTERALERT)) { 314 /* Check if this is a mld message */ 315 u8 nexthdr = hdr->nexthdr; 316 __be16 frag_off; 317 int offset; 318 319 /* Check if the value of Router Alert 320 * is for MLD (0x0000). 321 */ 322 if (opt->ra == htons(IPV6_OPT_ROUTERALERT_MLD)) { 323 deliver = false; 324 325 if (!ipv6_ext_hdr(nexthdr)) { 326 /* BUG */ 327 goto out; 328 } 329 offset = ipv6_skip_exthdr(skb, sizeof(*hdr), 330 &nexthdr, &frag_off); 331 if (offset < 0) 332 goto out; 333 334 if (ipv6_is_mld(skb, nexthdr, offset)) 335 deliver = true; 336 337 goto out; 338 } 339 /* unknown RA - process it normally */ 340 } 341 342 if (deliver) 343 skb2 = skb_clone(skb, GFP_ATOMIC); 344 else { 345 skb2 = skb; 346 skb = NULL; 347 } 348 349 if (skb2) { 350 ip6_mr_input(skb2); 351 } 352 } 353 out: 354 #endif 355 if (likely(deliver)) 356 ip6_input(skb); 357 else { 358 /* discard */ 359 kfree_skb(skb); 360 } 361 362 return 0; 363 } 364