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 inline int ip6_rcv_finish( struct sk_buff *skb) 51 { 52 if (skb_dst(skb) == NULL) 53 ip6_route_input(skb); 54 55 return dst_input(skb); 56 } 57 58 int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev) 59 { 60 const struct ipv6hdr *hdr; 61 u32 pkt_len; 62 struct inet6_dev *idev; 63 struct net *net = dev_net(skb->dev); 64 65 if (skb->pkt_type == PACKET_OTHERHOST) { 66 kfree_skb(skb); 67 return NET_RX_DROP; 68 } 69 70 rcu_read_lock(); 71 72 idev = __in6_dev_get(skb->dev); 73 74 IP6_UPD_PO_STATS_BH(net, idev, IPSTATS_MIB_IN, skb->len); 75 76 if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL || 77 !idev || unlikely(idev->cnf.disable_ipv6)) { 78 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS); 79 goto drop; 80 } 81 82 memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm)); 83 84 /* 85 * Store incoming device index. When the packet will 86 * be queued, we cannot refer to skb->dev anymore. 87 * 88 * BTW, when we send a packet for our own local address on a 89 * non-loopback interface (e.g. ethX), it is being delivered 90 * via the loopback interface (lo) here; skb->dev = loopback_dev. 91 * It, however, should be considered as if it is being 92 * arrived via the sending interface (ethX), because of the 93 * nature of scoping architecture. --yoshfuji 94 */ 95 IP6CB(skb)->iif = skb_dst(skb) ? ip6_dst_idev(skb_dst(skb))->dev->ifindex : dev->ifindex; 96 97 if (unlikely(!pskb_may_pull(skb, sizeof(*hdr)))) 98 goto err; 99 100 hdr = ipv6_hdr(skb); 101 102 if (hdr->version != 6) 103 goto err; 104 105 /* 106 * RFC4291 2.5.3 107 * A packet received on an interface with a destination address 108 * of loopback must be dropped. 109 */ 110 if (!(dev->flags & IFF_LOOPBACK) && 111 ipv6_addr_loopback(&hdr->daddr)) 112 goto err; 113 114 /* 115 * RFC4291 2.7 116 * Multicast addresses must not be used as source addresses in IPv6 117 * packets or appear in any Routing header. 118 */ 119 if (ipv6_addr_is_multicast(&hdr->saddr)) 120 goto err; 121 122 skb->transport_header = skb->network_header + sizeof(*hdr); 123 IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr); 124 125 pkt_len = ntohs(hdr->payload_len); 126 127 /* pkt_len may be zero if Jumbo payload option is present */ 128 if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) { 129 if (pkt_len + sizeof(struct ipv6hdr) > skb->len) { 130 IP6_INC_STATS_BH(net, 131 idev, IPSTATS_MIB_INTRUNCATEDPKTS); 132 goto drop; 133 } 134 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) { 135 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS); 136 goto drop; 137 } 138 hdr = ipv6_hdr(skb); 139 } 140 141 if (hdr->nexthdr == NEXTHDR_HOP) { 142 if (ipv6_parse_hopopts(skb) < 0) { 143 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS); 144 rcu_read_unlock(); 145 return NET_RX_DROP; 146 } 147 } 148 149 rcu_read_unlock(); 150 151 /* Must drop socket now because of tproxy. */ 152 skb_orphan(skb); 153 154 return NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, skb, dev, NULL, 155 ip6_rcv_finish); 156 err: 157 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS); 158 drop: 159 rcu_read_unlock(); 160 kfree_skb(skb); 161 return NET_RX_DROP; 162 } 163 164 /* 165 * Deliver the packet to the host 166 */ 167 168 169 static int ip6_input_finish(struct sk_buff *skb) 170 { 171 const struct inet6_protocol *ipprot; 172 unsigned int nhoff; 173 int nexthdr; 174 bool raw; 175 u8 hash; 176 struct inet6_dev *idev; 177 struct net *net = dev_net(skb_dst(skb)->dev); 178 179 /* 180 * Parse extension headers 181 */ 182 183 rcu_read_lock(); 184 resubmit: 185 idev = ip6_dst_idev(skb_dst(skb)); 186 if (!pskb_pull(skb, skb_transport_offset(skb))) 187 goto discard; 188 nhoff = IP6CB(skb)->nhoff; 189 nexthdr = skb_network_header(skb)[nhoff]; 190 191 raw = raw6_local_deliver(skb, nexthdr); 192 193 hash = nexthdr & (MAX_INET_PROTOS - 1); 194 if ((ipprot = rcu_dereference(inet6_protos[hash])) != NULL) { 195 int ret; 196 197 if (ipprot->flags & INET6_PROTO_FINAL) { 198 const struct ipv6hdr *hdr; 199 200 /* Free reference early: we don't need it any more, 201 and it may hold ip_conntrack module loaded 202 indefinitely. */ 203 nf_reset(skb); 204 205 skb_postpull_rcsum(skb, skb_network_header(skb), 206 skb_network_header_len(skb)); 207 hdr = ipv6_hdr(skb); 208 if (ipv6_addr_is_multicast(&hdr->daddr) && 209 !ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, 210 &hdr->saddr) && 211 !ipv6_is_mld(skb, nexthdr)) 212 goto discard; 213 } 214 if (!(ipprot->flags & INET6_PROTO_NOPOLICY) && 215 !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) 216 goto discard; 217 218 ret = ipprot->handler(skb); 219 if (ret > 0) 220 goto resubmit; 221 else if (ret == 0) 222 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS); 223 } else { 224 if (!raw) { 225 if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) { 226 IP6_INC_STATS_BH(net, idev, 227 IPSTATS_MIB_INUNKNOWNPROTOS); 228 icmpv6_send(skb, ICMPV6_PARAMPROB, 229 ICMPV6_UNK_NEXTHDR, nhoff); 230 } 231 } else 232 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS); 233 kfree_skb(skb); 234 } 235 rcu_read_unlock(); 236 return 0; 237 238 discard: 239 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS); 240 rcu_read_unlock(); 241 kfree_skb(skb); 242 return 0; 243 } 244 245 246 int ip6_input(struct sk_buff *skb) 247 { 248 return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_IN, skb, skb->dev, NULL, 249 ip6_input_finish); 250 } 251 252 int ip6_mc_input(struct sk_buff *skb) 253 { 254 const struct ipv6hdr *hdr; 255 bool deliver; 256 257 IP6_UPD_PO_STATS_BH(dev_net(skb_dst(skb)->dev), 258 ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INMCAST, 259 skb->len); 260 261 hdr = ipv6_hdr(skb); 262 deliver = ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, NULL); 263 264 #ifdef CONFIG_IPV6_MROUTE 265 /* 266 * IPv6 multicast router mode is now supported ;) 267 */ 268 if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding && 269 !(ipv6_addr_type(&hdr->daddr) & IPV6_ADDR_LINKLOCAL) && 270 likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) { 271 /* 272 * Okay, we try to forward - split and duplicate 273 * packets. 274 */ 275 struct sk_buff *skb2; 276 struct inet6_skb_parm *opt = IP6CB(skb); 277 278 /* Check for MLD */ 279 if (unlikely(opt->ra)) { 280 /* Check if this is a mld message */ 281 u8 *ptr = skb_network_header(skb) + opt->ra; 282 struct icmp6hdr *icmp6; 283 u8 nexthdr = hdr->nexthdr; 284 __be16 frag_off; 285 int offset; 286 287 /* Check if the value of Router Alert 288 * is for MLD (0x0000). 289 */ 290 if ((ptr[2] | ptr[3]) == 0) { 291 deliver = false; 292 293 if (!ipv6_ext_hdr(nexthdr)) { 294 /* BUG */ 295 goto out; 296 } 297 offset = ipv6_skip_exthdr(skb, sizeof(*hdr), 298 &nexthdr, &frag_off); 299 if (offset < 0) 300 goto out; 301 302 if (nexthdr != IPPROTO_ICMPV6) 303 goto out; 304 305 if (!pskb_may_pull(skb, (skb_network_header(skb) + 306 offset + 1 - skb->data))) 307 goto out; 308 309 icmp6 = (struct icmp6hdr *)(skb_network_header(skb) + offset); 310 311 switch (icmp6->icmp6_type) { 312 case ICMPV6_MGM_QUERY: 313 case ICMPV6_MGM_REPORT: 314 case ICMPV6_MGM_REDUCTION: 315 case ICMPV6_MLD2_REPORT: 316 deliver = true; 317 break; 318 } 319 goto out; 320 } 321 /* unknown RA - process it normally */ 322 } 323 324 if (deliver) 325 skb2 = skb_clone(skb, GFP_ATOMIC); 326 else { 327 skb2 = skb; 328 skb = NULL; 329 } 330 331 if (skb2) { 332 ip6_mr_input(skb2); 333 } 334 } 335 out: 336 #endif 337 if (likely(deliver)) 338 ip6_input(skb); 339 else { 340 /* discard */ 341 kfree_skb(skb); 342 } 343 344 return 0; 345 } 346