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