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 struct net *net = dev_net(skb_dst(skb)->dev); 172 const struct inet6_protocol *ipprot; 173 struct inet6_dev *idev; 174 unsigned int nhoff; 175 int nexthdr; 176 bool raw; 177 178 /* 179 * Parse extension headers 180 */ 181 182 rcu_read_lock(); 183 resubmit: 184 idev = ip6_dst_idev(skb_dst(skb)); 185 if (!pskb_pull(skb, skb_transport_offset(skb))) 186 goto discard; 187 nhoff = IP6CB(skb)->nhoff; 188 nexthdr = skb_network_header(skb)[nhoff]; 189 190 raw = raw6_local_deliver(skb, nexthdr); 191 if ((ipprot = rcu_dereference(inet6_protos[nexthdr])) != NULL) { 192 int ret; 193 194 if (ipprot->flags & INET6_PROTO_FINAL) { 195 const struct ipv6hdr *hdr; 196 197 /* Free reference early: we don't need it any more, 198 and it may hold ip_conntrack module loaded 199 indefinitely. */ 200 nf_reset(skb); 201 202 skb_postpull_rcsum(skb, skb_network_header(skb), 203 skb_network_header_len(skb)); 204 hdr = ipv6_hdr(skb); 205 if (ipv6_addr_is_multicast(&hdr->daddr) && 206 !ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, 207 &hdr->saddr) && 208 !ipv6_is_mld(skb, nexthdr)) 209 goto discard; 210 } 211 if (!(ipprot->flags & INET6_PROTO_NOPOLICY) && 212 !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) 213 goto discard; 214 215 ret = ipprot->handler(skb); 216 if (ret > 0) 217 goto resubmit; 218 else if (ret == 0) 219 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS); 220 } else { 221 if (!raw) { 222 if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) { 223 IP6_INC_STATS_BH(net, idev, 224 IPSTATS_MIB_INUNKNOWNPROTOS); 225 icmpv6_send(skb, ICMPV6_PARAMPROB, 226 ICMPV6_UNK_NEXTHDR, nhoff); 227 } 228 } else 229 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDELIVERS); 230 kfree_skb(skb); 231 } 232 rcu_read_unlock(); 233 return 0; 234 235 discard: 236 IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INDISCARDS); 237 rcu_read_unlock(); 238 kfree_skb(skb); 239 return 0; 240 } 241 242 243 int ip6_input(struct sk_buff *skb) 244 { 245 return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_IN, skb, skb->dev, NULL, 246 ip6_input_finish); 247 } 248 249 int ip6_mc_input(struct sk_buff *skb) 250 { 251 const struct ipv6hdr *hdr; 252 bool deliver; 253 254 IP6_UPD_PO_STATS_BH(dev_net(skb_dst(skb)->dev), 255 ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INMCAST, 256 skb->len); 257 258 hdr = ipv6_hdr(skb); 259 deliver = ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, NULL); 260 261 #ifdef CONFIG_IPV6_MROUTE 262 /* 263 * IPv6 multicast router mode is now supported ;) 264 */ 265 if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding && 266 !(ipv6_addr_type(&hdr->daddr) & IPV6_ADDR_LINKLOCAL) && 267 likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) { 268 /* 269 * Okay, we try to forward - split and duplicate 270 * packets. 271 */ 272 struct sk_buff *skb2; 273 struct inet6_skb_parm *opt = IP6CB(skb); 274 275 /* Check for MLD */ 276 if (unlikely(opt->ra)) { 277 /* Check if this is a mld message */ 278 u8 *ptr = skb_network_header(skb) + opt->ra; 279 struct icmp6hdr *icmp6; 280 u8 nexthdr = hdr->nexthdr; 281 __be16 frag_off; 282 int offset; 283 284 /* Check if the value of Router Alert 285 * is for MLD (0x0000). 286 */ 287 if ((ptr[2] | ptr[3]) == 0) { 288 deliver = false; 289 290 if (!ipv6_ext_hdr(nexthdr)) { 291 /* BUG */ 292 goto out; 293 } 294 offset = ipv6_skip_exthdr(skb, sizeof(*hdr), 295 &nexthdr, &frag_off); 296 if (offset < 0) 297 goto out; 298 299 if (nexthdr != IPPROTO_ICMPV6) 300 goto out; 301 302 if (!pskb_may_pull(skb, (skb_network_header(skb) + 303 offset + 1 - skb->data))) 304 goto out; 305 306 icmp6 = (struct icmp6hdr *)(skb_network_header(skb) + offset); 307 308 switch (icmp6->icmp6_type) { 309 case ICMPV6_MGM_QUERY: 310 case ICMPV6_MGM_REPORT: 311 case ICMPV6_MGM_REDUCTION: 312 case ICMPV6_MLD2_REPORT: 313 deliver = true; 314 break; 315 } 316 goto out; 317 } 318 /* unknown RA - process it normally */ 319 } 320 321 if (deliver) 322 skb2 = skb_clone(skb, GFP_ATOMIC); 323 else { 324 skb2 = skb; 325 skb = NULL; 326 } 327 328 if (skb2) { 329 ip6_mr_input(skb2); 330 } 331 } 332 out: 333 #endif 334 if (likely(deliver)) 335 ip6_input(skb); 336 else { 337 /* discard */ 338 kfree_skb(skb); 339 } 340 341 return 0; 342 } 343