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 rcu_read_lock(); 56 ipprot = rcu_dereference(inet6_protos[ipv6_hdr(skb)->nexthdr]); 57 if (ipprot && ipprot->early_demux) 58 ipprot->early_demux(skb); 59 rcu_read_unlock(); 60 } 61 if (!skb_dst(skb)) 62 ip6_route_input(skb); 63 64 return dst_input(skb); 65 } 66 67 int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev) 68 { 69 const struct ipv6hdr *hdr; 70 u32 pkt_len; 71 struct inet6_dev *idev; 72 struct net *net = dev_net(skb->dev); 73 74 if (skb->pkt_type == PACKET_OTHERHOST) { 75 kfree_skb(skb); 76 return NET_RX_DROP; 77 } 78 79 rcu_read_lock(); 80 81 idev = __in6_dev_get(skb->dev); 82 83 IP6_UPD_PO_STATS_BH(net, idev, IPSTATS_MIB_IN, skb->len); 84 85 if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL || 86 !idev || unlikely(idev->cnf.disable_ipv6)) { 87 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS); 88 goto drop; 89 } 90 91 memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm)); 92 93 /* 94 * Store incoming device index. When the packet will 95 * be queued, we cannot refer to skb->dev anymore. 96 * 97 * BTW, when we send a packet for our own local address on a 98 * non-loopback interface (e.g. ethX), it is being delivered 99 * via the loopback interface (lo) here; skb->dev = loopback_dev. 100 * It, however, should be considered as if it is being 101 * arrived via the sending interface (ethX), because of the 102 * nature of scoping architecture. --yoshfuji 103 */ 104 IP6CB(skb)->iif = skb_dst(skb) ? ip6_dst_idev(skb_dst(skb))->dev->ifindex : dev->ifindex; 105 106 if (unlikely(!pskb_may_pull(skb, sizeof(*hdr)))) 107 goto err; 108 109 hdr = ipv6_hdr(skb); 110 111 if (hdr->version != 6) 112 goto err; 113 114 /* 115 * RFC4291 2.5.3 116 * A packet received on an interface with a destination address 117 * of loopback must be dropped. 118 */ 119 if (!(dev->flags & IFF_LOOPBACK) && 120 ipv6_addr_loopback(&hdr->daddr)) 121 goto err; 122 123 /* 124 * RFC4291 2.7 125 * Multicast addresses must not be used as source addresses in IPv6 126 * packets or appear in any Routing header. 127 */ 128 if (ipv6_addr_is_multicast(&hdr->saddr)) 129 goto err; 130 131 skb->transport_header = skb->network_header + sizeof(*hdr); 132 IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr); 133 134 pkt_len = ntohs(hdr->payload_len); 135 136 /* pkt_len may be zero if Jumbo payload option is present */ 137 if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) { 138 if (pkt_len + sizeof(struct ipv6hdr) > skb->len) { 139 IP6_INC_STATS_BH(net, 140 idev, IPSTATS_MIB_INTRUNCATEDPKTS); 141 goto drop; 142 } 143 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) { 144 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS); 145 goto drop; 146 } 147 hdr = ipv6_hdr(skb); 148 } 149 150 if (hdr->nexthdr == NEXTHDR_HOP) { 151 if (ipv6_parse_hopopts(skb) < 0) { 152 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS); 153 rcu_read_unlock(); 154 return NET_RX_DROP; 155 } 156 } 157 158 rcu_read_unlock(); 159 160 /* Must drop socket now because of tproxy. */ 161 skb_orphan(skb); 162 163 return NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, skb, dev, NULL, 164 ip6_rcv_finish); 165 err: 166 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS); 167 drop: 168 rcu_read_unlock(); 169 kfree_skb(skb); 170 return NET_RX_DROP; 171 } 172 173 /* 174 * Deliver the packet to the host 175 */ 176 177 178 static int ip6_input_finish(struct sk_buff *skb) 179 { 180 struct net *net = dev_net(skb_dst(skb)->dev); 181 const struct inet6_protocol *ipprot; 182 struct inet6_dev *idev; 183 unsigned int nhoff; 184 int nexthdr; 185 bool raw; 186 187 /* 188 * Parse extension headers 189 */ 190 191 rcu_read_lock(); 192 resubmit: 193 idev = ip6_dst_idev(skb_dst(skb)); 194 if (!pskb_pull(skb, skb_transport_offset(skb))) 195 goto discard; 196 nhoff = IP6CB(skb)->nhoff; 197 nexthdr = skb_network_header(skb)[nhoff]; 198 199 raw = raw6_local_deliver(skb, nexthdr); 200 if ((ipprot = rcu_dereference(inet6_protos[nexthdr])) != NULL) { 201 int ret; 202 203 if (ipprot->flags & INET6_PROTO_FINAL) { 204 const struct ipv6hdr *hdr; 205 206 /* Free reference early: we don't need it any more, 207 and it may hold ip_conntrack module loaded 208 indefinitely. */ 209 nf_reset(skb); 210 211 skb_postpull_rcsum(skb, skb_network_header(skb), 212 skb_network_header_len(skb)); 213 hdr = ipv6_hdr(skb); 214 if (ipv6_addr_is_multicast(&hdr->daddr) && 215 !ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, 216 &hdr->saddr) && 217 !ipv6_is_mld(skb, nexthdr)) 218 goto discard; 219 } 220 if (!(ipprot->flags & INET6_PROTO_NOPOLICY) && 221 !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) 222 goto discard; 223 224 ret = ipprot->handler(skb); 225 if (ret > 0) 226 goto resubmit; 227 else if (ret == 0) 228 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS); 229 } else { 230 if (!raw) { 231 if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) { 232 IP6_INC_STATS_BH(net, idev, 233 IPSTATS_MIB_INUNKNOWNPROTOS); 234 icmpv6_send(skb, ICMPV6_PARAMPROB, 235 ICMPV6_UNK_NEXTHDR, nhoff); 236 } 237 } else 238 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS); 239 kfree_skb(skb); 240 } 241 rcu_read_unlock(); 242 return 0; 243 244 discard: 245 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS); 246 rcu_read_unlock(); 247 kfree_skb(skb); 248 return 0; 249 } 250 251 252 int ip6_input(struct sk_buff *skb) 253 { 254 return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_IN, skb, skb->dev, NULL, 255 ip6_input_finish); 256 } 257 258 int ip6_mc_input(struct sk_buff *skb) 259 { 260 const struct ipv6hdr *hdr; 261 bool deliver; 262 263 IP6_UPD_PO_STATS_BH(dev_net(skb_dst(skb)->dev), 264 ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INMCAST, 265 skb->len); 266 267 hdr = ipv6_hdr(skb); 268 deliver = ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, NULL); 269 270 #ifdef CONFIG_IPV6_MROUTE 271 /* 272 * IPv6 multicast router mode is now supported ;) 273 */ 274 if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding && 275 !(ipv6_addr_type(&hdr->daddr) & IPV6_ADDR_LINKLOCAL) && 276 likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) { 277 /* 278 * Okay, we try to forward - split and duplicate 279 * packets. 280 */ 281 struct sk_buff *skb2; 282 struct inet6_skb_parm *opt = IP6CB(skb); 283 284 /* Check for MLD */ 285 if (unlikely(opt->ra)) { 286 /* Check if this is a mld message */ 287 u8 *ptr = skb_network_header(skb) + opt->ra; 288 struct icmp6hdr *icmp6; 289 u8 nexthdr = hdr->nexthdr; 290 __be16 frag_off; 291 int offset; 292 293 /* Check if the value of Router Alert 294 * is for MLD (0x0000). 295 */ 296 if ((ptr[2] | ptr[3]) == 0) { 297 deliver = false; 298 299 if (!ipv6_ext_hdr(nexthdr)) { 300 /* BUG */ 301 goto out; 302 } 303 offset = ipv6_skip_exthdr(skb, sizeof(*hdr), 304 &nexthdr, &frag_off); 305 if (offset < 0) 306 goto out; 307 308 if (nexthdr != IPPROTO_ICMPV6) 309 goto out; 310 311 if (!pskb_may_pull(skb, (skb_network_header(skb) + 312 offset + 1 - skb->data))) 313 goto out; 314 315 icmp6 = (struct icmp6hdr *)(skb_network_header(skb) + offset); 316 317 switch (icmp6->icmp6_type) { 318 case ICMPV6_MGM_QUERY: 319 case ICMPV6_MGM_REPORT: 320 case ICMPV6_MGM_REDUCTION: 321 case ICMPV6_MLD2_REPORT: 322 deliver = true; 323 break; 324 } 325 goto out; 326 } 327 /* unknown RA - process it normally */ 328 } 329 330 if (deliver) 331 skb2 = skb_clone(skb, GFP_ATOMIC); 332 else { 333 skb2 = skb; 334 skb = NULL; 335 } 336 337 if (skb2) { 338 ip6_mr_input(skb2); 339 } 340 } 341 out: 342 #endif 343 if (likely(deliver)) 344 ip6_input(skb); 345 else { 346 /* discard */ 347 kfree_skb(skb); 348 } 349 350 return 0; 351 } 352