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 48 49 50 int ip6_rcv_finish(struct sk_buff *skb) 51 { 52 if (sysctl_ip_early_demux && !skb_dst(skb)) { 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_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_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 /* 113 * RFC4291 2.5.3 114 * A packet received on an interface with a destination address 115 * of loopback must be dropped. 116 */ 117 if (!(dev->flags & IFF_LOOPBACK) && 118 ipv6_addr_loopback(&hdr->daddr)) 119 goto err; 120 121 /* RFC4291 Errata ID: 3480 122 * Interface-Local scope spans only a single interface on a 123 * node and is useful only for loopback transmission of 124 * multicast. Packets with interface-local scope received 125 * from another node must be discarded. 126 */ 127 if (!(skb->pkt_type == PACKET_LOOPBACK || 128 dev->flags & IFF_LOOPBACK) && 129 ipv6_addr_is_multicast(&hdr->daddr) && 130 IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 1) 131 goto err; 132 133 /* RFC4291 2.7 134 * Nodes must not originate a packet to a multicast address whose scope 135 * field contains the reserved value 0; if such a packet is received, it 136 * must be silently dropped. 137 */ 138 if (ipv6_addr_is_multicast(&hdr->daddr) && 139 IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 0) 140 goto err; 141 142 /* 143 * RFC4291 2.7 144 * Multicast addresses must not be used as source addresses in IPv6 145 * packets or appear in any Routing header. 146 */ 147 if (ipv6_addr_is_multicast(&hdr->saddr)) 148 goto err; 149 150 skb->transport_header = skb->network_header + sizeof(*hdr); 151 IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr); 152 153 pkt_len = ntohs(hdr->payload_len); 154 155 /* pkt_len may be zero if Jumbo payload option is present */ 156 if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) { 157 if (pkt_len + sizeof(struct ipv6hdr) > skb->len) { 158 IP6_INC_STATS_BH(net, 159 idev, IPSTATS_MIB_INTRUNCATEDPKTS); 160 goto drop; 161 } 162 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) { 163 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS); 164 goto drop; 165 } 166 hdr = ipv6_hdr(skb); 167 } 168 169 if (hdr->nexthdr == NEXTHDR_HOP) { 170 if (ipv6_parse_hopopts(skb) < 0) { 171 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS); 172 rcu_read_unlock(); 173 return NET_RX_DROP; 174 } 175 } 176 177 rcu_read_unlock(); 178 179 /* Must drop socket now because of tproxy. */ 180 skb_orphan(skb); 181 182 return NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, skb, dev, NULL, 183 ip6_rcv_finish); 184 err: 185 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS); 186 drop: 187 rcu_read_unlock(); 188 kfree_skb(skb); 189 return NET_RX_DROP; 190 } 191 192 /* 193 * Deliver the packet to the host 194 */ 195 196 197 static int ip6_input_finish(struct sk_buff *skb) 198 { 199 struct net *net = dev_net(skb_dst(skb)->dev); 200 const struct inet6_protocol *ipprot; 201 struct inet6_dev *idev; 202 unsigned int nhoff; 203 int nexthdr; 204 bool raw; 205 206 /* 207 * Parse extension headers 208 */ 209 210 rcu_read_lock(); 211 resubmit: 212 idev = ip6_dst_idev(skb_dst(skb)); 213 if (!pskb_pull(skb, skb_transport_offset(skb))) 214 goto discard; 215 nhoff = IP6CB(skb)->nhoff; 216 nexthdr = skb_network_header(skb)[nhoff]; 217 218 raw = raw6_local_deliver(skb, nexthdr); 219 if ((ipprot = rcu_dereference(inet6_protos[nexthdr])) != NULL) { 220 int ret; 221 222 if (ipprot->flags & INET6_PROTO_FINAL) { 223 const struct ipv6hdr *hdr; 224 225 /* Free reference early: we don't need it any more, 226 and it may hold ip_conntrack module loaded 227 indefinitely. */ 228 nf_reset(skb); 229 230 skb_postpull_rcsum(skb, skb_network_header(skb), 231 skb_network_header_len(skb)); 232 hdr = ipv6_hdr(skb); 233 if (ipv6_addr_is_multicast(&hdr->daddr) && 234 !ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, 235 &hdr->saddr) && 236 !ipv6_is_mld(skb, nexthdr, skb_network_header_len(skb))) 237 goto discard; 238 } 239 if (!(ipprot->flags & INET6_PROTO_NOPOLICY) && 240 !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) 241 goto discard; 242 243 ret = ipprot->handler(skb); 244 if (ret > 0) 245 goto resubmit; 246 else if (ret == 0) 247 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS); 248 } else { 249 if (!raw) { 250 if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) { 251 IP6_INC_STATS_BH(net, idev, 252 IPSTATS_MIB_INUNKNOWNPROTOS); 253 icmpv6_send(skb, ICMPV6_PARAMPROB, 254 ICMPV6_UNK_NEXTHDR, nhoff); 255 } 256 kfree_skb(skb); 257 } else { 258 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS); 259 consume_skb(skb); 260 } 261 } 262 rcu_read_unlock(); 263 return 0; 264 265 discard: 266 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS); 267 rcu_read_unlock(); 268 kfree_skb(skb); 269 return 0; 270 } 271 272 273 int ip6_input(struct sk_buff *skb) 274 { 275 return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_IN, skb, skb->dev, NULL, 276 ip6_input_finish); 277 } 278 279 int ip6_mc_input(struct sk_buff *skb) 280 { 281 const struct ipv6hdr *hdr; 282 bool deliver; 283 284 IP6_UPD_PO_STATS_BH(dev_net(skb_dst(skb)->dev), 285 ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INMCAST, 286 skb->len); 287 288 hdr = ipv6_hdr(skb); 289 deliver = ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, NULL); 290 291 #ifdef CONFIG_IPV6_MROUTE 292 /* 293 * IPv6 multicast router mode is now supported ;) 294 */ 295 if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding && 296 !(ipv6_addr_type(&hdr->daddr) & 297 (IPV6_ADDR_LOOPBACK|IPV6_ADDR_LINKLOCAL)) && 298 likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) { 299 /* 300 * Okay, we try to forward - split and duplicate 301 * packets. 302 */ 303 struct sk_buff *skb2; 304 struct inet6_skb_parm *opt = IP6CB(skb); 305 306 /* Check for MLD */ 307 if (unlikely(opt->flags & IP6SKB_ROUTERALERT)) { 308 /* Check if this is a mld message */ 309 u8 nexthdr = hdr->nexthdr; 310 __be16 frag_off; 311 int offset; 312 313 /* Check if the value of Router Alert 314 * is for MLD (0x0000). 315 */ 316 if (opt->ra == htons(IPV6_OPT_ROUTERALERT_MLD)) { 317 deliver = false; 318 319 if (!ipv6_ext_hdr(nexthdr)) { 320 /* BUG */ 321 goto out; 322 } 323 offset = ipv6_skip_exthdr(skb, sizeof(*hdr), 324 &nexthdr, &frag_off); 325 if (offset < 0) 326 goto out; 327 328 if (!ipv6_is_mld(skb, nexthdr, offset)) 329 goto out; 330 331 deliver = true; 332 } 333 /* unknown RA - process it normally */ 334 } 335 336 if (deliver) 337 skb2 = skb_clone(skb, GFP_ATOMIC); 338 else { 339 skb2 = skb; 340 skb = NULL; 341 } 342 343 if (skb2) { 344 ip6_mr_input(skb2); 345 } 346 } 347 out: 348 #endif 349 if (likely(deliver)) 350 ip6_input(skb); 351 else { 352 /* discard */ 353 kfree_skb(skb); 354 } 355 356 return 0; 357 } 358