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 32 #include <linux/netfilter.h> 33 #include <linux/netfilter_ipv6.h> 34 35 #include <net/sock.h> 36 #include <net/snmp.h> 37 38 #include <net/ipv6.h> 39 #include <net/protocol.h> 40 #include <net/transp_v6.h> 41 #include <net/rawv6.h> 42 #include <net/ndisc.h> 43 #include <net/ip6_route.h> 44 #include <net/addrconf.h> 45 #include <net/xfrm.h> 46 47 48 49 inline int ip6_rcv_finish( struct sk_buff *skb) 50 { 51 if (skb->dst == NULL) 52 ip6_route_input(skb); 53 54 return dst_input(skb); 55 } 56 57 int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev) 58 { 59 struct ipv6hdr *hdr; 60 u32 pkt_len; 61 struct inet6_dev *idev; 62 struct net *net = dev_net(skb->dev); 63 64 if (skb->pkt_type == PACKET_OTHERHOST) { 65 kfree_skb(skb); 66 return 0; 67 } 68 69 rcu_read_lock(); 70 71 idev = __in6_dev_get(skb->dev); 72 73 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INRECEIVES); 74 75 if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL || 76 !idev || unlikely(idev->cnf.disable_ipv6)) { 77 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS); 78 goto drop; 79 } 80 81 memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm)); 82 83 /* 84 * Store incoming device index. When the packet will 85 * be queued, we cannot refer to skb->dev anymore. 86 * 87 * BTW, when we send a packet for our own local address on a 88 * non-loopback interface (e.g. ethX), it is being delivered 89 * via the loopback interface (lo) here; skb->dev = loopback_dev. 90 * It, however, should be considered as if it is being 91 * arrived via the sending interface (ethX), because of the 92 * nature of scoping architecture. --yoshfuji 93 */ 94 IP6CB(skb)->iif = skb->dst ? ip6_dst_idev(skb->dst)->dev->ifindex : dev->ifindex; 95 96 if (unlikely(!pskb_may_pull(skb, sizeof(*hdr)))) 97 goto err; 98 99 hdr = ipv6_hdr(skb); 100 101 if (hdr->version != 6) 102 goto err; 103 104 /* 105 * RFC4291 2.5.3 106 * A packet received on an interface with a destination address 107 * of loopback must be dropped. 108 */ 109 if (!(dev->flags & IFF_LOOPBACK) && 110 ipv6_addr_loopback(&hdr->daddr)) 111 goto err; 112 113 skb->transport_header = skb->network_header + sizeof(*hdr); 114 IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr); 115 116 pkt_len = ntohs(hdr->payload_len); 117 118 /* pkt_len may be zero if Jumbo payload option is present */ 119 if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) { 120 if (pkt_len + sizeof(struct ipv6hdr) > skb->len) { 121 IP6_INC_STATS_BH(net, 122 idev, IPSTATS_MIB_INTRUNCATEDPKTS); 123 goto drop; 124 } 125 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) { 126 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS); 127 goto drop; 128 } 129 hdr = ipv6_hdr(skb); 130 } 131 132 if (hdr->nexthdr == NEXTHDR_HOP) { 133 if (ipv6_parse_hopopts(skb) < 0) { 134 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS); 135 rcu_read_unlock(); 136 return 0; 137 } 138 } 139 140 rcu_read_unlock(); 141 142 return NF_HOOK(PF_INET6, NF_INET_PRE_ROUTING, skb, dev, NULL, 143 ip6_rcv_finish); 144 err: 145 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS); 146 drop: 147 rcu_read_unlock(); 148 kfree_skb(skb); 149 return 0; 150 } 151 152 /* 153 * Deliver the packet to the host 154 */ 155 156 157 static int ip6_input_finish(struct sk_buff *skb) 158 { 159 struct inet6_protocol *ipprot; 160 unsigned int nhoff; 161 int nexthdr, raw; 162 u8 hash; 163 struct inet6_dev *idev; 164 struct net *net = dev_net(skb->dst->dev); 165 166 /* 167 * Parse extension headers 168 */ 169 170 rcu_read_lock(); 171 resubmit: 172 idev = ip6_dst_idev(skb->dst); 173 if (!pskb_pull(skb, skb_transport_offset(skb))) 174 goto discard; 175 nhoff = IP6CB(skb)->nhoff; 176 nexthdr = skb_network_header(skb)[nhoff]; 177 178 raw = raw6_local_deliver(skb, nexthdr); 179 180 hash = nexthdr & (MAX_INET_PROTOS - 1); 181 if ((ipprot = rcu_dereference(inet6_protos[hash])) != NULL) { 182 int ret; 183 184 if (ipprot->flags & INET6_PROTO_FINAL) { 185 struct ipv6hdr *hdr; 186 187 /* Free reference early: we don't need it any more, 188 and it may hold ip_conntrack module loaded 189 indefinitely. */ 190 nf_reset(skb); 191 192 skb_postpull_rcsum(skb, skb_network_header(skb), 193 skb_network_header_len(skb)); 194 hdr = ipv6_hdr(skb); 195 if (ipv6_addr_is_multicast(&hdr->daddr) && 196 !ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, 197 &hdr->saddr) && 198 !ipv6_is_mld(skb, nexthdr)) 199 goto discard; 200 } 201 if (!(ipprot->flags & INET6_PROTO_NOPOLICY) && 202 !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) 203 goto discard; 204 205 ret = ipprot->handler(skb); 206 if (ret > 0) 207 goto resubmit; 208 else if (ret == 0) 209 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS); 210 } else { 211 if (!raw) { 212 if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) { 213 IP6_INC_STATS_BH(net, idev, 214 IPSTATS_MIB_INUNKNOWNPROTOS); 215 icmpv6_send(skb, ICMPV6_PARAMPROB, 216 ICMPV6_UNK_NEXTHDR, nhoff, 217 skb->dev); 218 } 219 } else 220 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS); 221 kfree_skb(skb); 222 } 223 rcu_read_unlock(); 224 return 0; 225 226 discard: 227 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS); 228 rcu_read_unlock(); 229 kfree_skb(skb); 230 return 0; 231 } 232 233 234 int ip6_input(struct sk_buff *skb) 235 { 236 return NF_HOOK(PF_INET6, NF_INET_LOCAL_IN, skb, skb->dev, NULL, 237 ip6_input_finish); 238 } 239 240 int ip6_mc_input(struct sk_buff *skb) 241 { 242 struct ipv6hdr *hdr; 243 int deliver; 244 245 IP6_INC_STATS_BH(dev_net(skb->dst->dev), 246 ip6_dst_idev(skb->dst), IPSTATS_MIB_INMCASTPKTS); 247 248 hdr = ipv6_hdr(skb); 249 deliver = ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, NULL); 250 251 #ifdef CONFIG_IPV6_MROUTE 252 /* 253 * IPv6 multicast router mode is now supported ;) 254 */ 255 if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding && 256 !(ipv6_addr_type(&hdr->daddr) & IPV6_ADDR_LINKLOCAL) && 257 likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) { 258 /* 259 * Okay, we try to forward - split and duplicate 260 * packets. 261 */ 262 struct sk_buff *skb2; 263 struct inet6_skb_parm *opt = IP6CB(skb); 264 265 /* Check for MLD */ 266 if (unlikely(opt->ra)) { 267 /* Check if this is a mld message */ 268 u8 *ptr = skb_network_header(skb) + opt->ra; 269 struct icmp6hdr *icmp6; 270 u8 nexthdr = hdr->nexthdr; 271 int offset; 272 273 /* Check if the value of Router Alert 274 * is for MLD (0x0000). 275 */ 276 if ((ptr[2] | ptr[3]) == 0) { 277 deliver = 0; 278 279 if (!ipv6_ext_hdr(nexthdr)) { 280 /* BUG */ 281 goto out; 282 } 283 offset = ipv6_skip_exthdr(skb, sizeof(*hdr), 284 &nexthdr); 285 if (offset < 0) 286 goto out; 287 288 if (nexthdr != IPPROTO_ICMPV6) 289 goto out; 290 291 if (!pskb_may_pull(skb, (skb_network_header(skb) + 292 offset + 1 - skb->data))) 293 goto out; 294 295 icmp6 = (struct icmp6hdr *)(skb_network_header(skb) + offset); 296 297 switch (icmp6->icmp6_type) { 298 case ICMPV6_MGM_QUERY: 299 case ICMPV6_MGM_REPORT: 300 case ICMPV6_MGM_REDUCTION: 301 case ICMPV6_MLD2_REPORT: 302 deliver = 1; 303 break; 304 } 305 goto out; 306 } 307 /* unknown RA - process it normally */ 308 } 309 310 if (deliver) 311 skb2 = skb_clone(skb, GFP_ATOMIC); 312 else { 313 skb2 = skb; 314 skb = NULL; 315 } 316 317 if (skb2) { 318 ip6_mr_input(skb2); 319 } 320 } 321 out: 322 #endif 323 if (likely(deliver)) 324 ip6_input(skb); 325 else { 326 /* discard */ 327 kfree_skb(skb); 328 } 329 330 return 0; 331 } 332