| 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
| 2 | /* |
| 3 | * INET An implementation of the TCP/IP protocol suite for the LINUX |
| 4 | * operating system. INET is implemented using the BSD Socket |
| 5 | * interface as the means of communication with the user level. |
| 6 | * |
| 7 | * The Internet Protocol (IP) module. |
| 8 | * |
| 9 | * Authors: Ross Biro |
| 10 | * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> |
| 11 | * Donald Becker, <becker@super.org> |
| 12 | * Alan Cox, <alan@lxorguk.ukuu.org.uk> |
| 13 | * Richard Underwood |
| 14 | * Stefan Becker, <stefanb@yello.ping.de> |
| 15 | * Jorge Cwik, <jorge@laser.satlink.net> |
| 16 | * Arnt Gulbrandsen, <agulbra@nvg.unit.no> |
| 17 | * |
| 18 | * Fixes: |
| 19 | * Alan Cox : Commented a couple of minor bits of surplus code |
| 20 | * Alan Cox : Undefining IP_FORWARD doesn't include the code |
| 21 | * (just stops a compiler warning). |
| 22 | * Alan Cox : Frames with >=MAX_ROUTE record routes, strict routes or loose routes |
| 23 | * are junked rather than corrupting things. |
| 24 | * Alan Cox : Frames to bad broadcast subnets are dumped |
| 25 | * We used to process them non broadcast and |
| 26 | * boy could that cause havoc. |
| 27 | * Alan Cox : ip_forward sets the free flag on the |
| 28 | * new frame it queues. Still crap because |
| 29 | * it copies the frame but at least it |
| 30 | * doesn't eat memory too. |
| 31 | * Alan Cox : Generic queue code and memory fixes. |
| 32 | * Fred Van Kempen : IP fragment support (borrowed from NET2E) |
| 33 | * Gerhard Koerting: Forward fragmented frames correctly. |
| 34 | * Gerhard Koerting: Fixes to my fix of the above 8-). |
| 35 | * Gerhard Koerting: IP interface addressing fix. |
| 36 | * Linus Torvalds : More robustness checks |
| 37 | * Alan Cox : Even more checks: Still not as robust as it ought to be |
| 38 | * Alan Cox : Save IP header pointer for later |
| 39 | * Alan Cox : ip option setting |
| 40 | * Alan Cox : Use ip_tos/ip_ttl settings |
| 41 | * Alan Cox : Fragmentation bogosity removed |
| 42 | * (Thanks to Mark.Bush@prg.ox.ac.uk) |
| 43 | * Dmitry Gorodchanin : Send of a raw packet crash fix. |
| 44 | * Alan Cox : Silly ip bug when an overlength |
| 45 | * fragment turns up. Now frees the |
| 46 | * queue. |
| 47 | * Linus Torvalds/ : Memory leakage on fragmentation |
| 48 | * Alan Cox : handling. |
| 49 | * Gerhard Koerting: Forwarding uses IP priority hints |
| 50 | * Teemu Rantanen : Fragment problems. |
| 51 | * Alan Cox : General cleanup, comments and reformat |
| 52 | * Alan Cox : SNMP statistics |
| 53 | * Alan Cox : BSD address rule semantics. Also see |
| 54 | * UDP as there is a nasty checksum issue |
| 55 | * if you do things the wrong way. |
| 56 | * Alan Cox : Always defrag, moved IP_FORWARD to the config.in file |
| 57 | * Alan Cox : IP options adjust sk->priority. |
| 58 | * Pedro Roque : Fix mtu/length error in ip_forward. |
| 59 | * Alan Cox : Avoid ip_chk_addr when possible. |
| 60 | * Richard Underwood : IP multicasting. |
| 61 | * Alan Cox : Cleaned up multicast handlers. |
| 62 | * Alan Cox : RAW sockets demultiplex in the BSD style. |
| 63 | * Gunther Mayer : Fix the SNMP reporting typo |
| 64 | * Alan Cox : Always in group 224.0.0.1 |
| 65 | * Pauline Middelink : Fast ip_checksum update when forwarding |
| 66 | * Masquerading support. |
| 67 | * Alan Cox : Multicast loopback error for 224.0.0.1 |
| 68 | * Alan Cox : IP_MULTICAST_LOOP option. |
| 69 | * Alan Cox : Use notifiers. |
| 70 | * Bjorn Ekwall : Removed ip_csum (from slhc.c too) |
| 71 | * Bjorn Ekwall : Moved ip_fast_csum to ip.h (inline!) |
| 72 | * Stefan Becker : Send out ICMP HOST REDIRECT |
| 73 | * Arnt Gulbrandsen : ip_build_xmit |
| 74 | * Alan Cox : Per socket routing cache |
| 75 | * Alan Cox : Fixed routing cache, added header cache. |
| 76 | * Alan Cox : Loopback didn't work right in original ip_build_xmit - fixed it. |
| 77 | * Alan Cox : Only send ICMP_REDIRECT if src/dest are the same net. |
| 78 | * Alan Cox : Incoming IP option handling. |
| 79 | * Alan Cox : Set saddr on raw output frames as per BSD. |
| 80 | * Alan Cox : Stopped broadcast source route explosions. |
| 81 | * Alan Cox : Can disable source routing |
| 82 | * Takeshi Sone : Masquerading didn't work. |
| 83 | * Dave Bonn,Alan Cox : Faster IP forwarding whenever possible. |
| 84 | * Alan Cox : Memory leaks, tramples, misc debugging. |
| 85 | * Alan Cox : Fixed multicast (by popular demand 8)) |
| 86 | * Alan Cox : Fixed forwarding (by even more popular demand 8)) |
| 87 | * Alan Cox : Fixed SNMP statistics [I think] |
| 88 | * Gerhard Koerting : IP fragmentation forwarding fix |
| 89 | * Alan Cox : Device lock against page fault. |
| 90 | * Alan Cox : IP_HDRINCL facility. |
| 91 | * Werner Almesberger : Zero fragment bug |
| 92 | * Alan Cox : RAW IP frame length bug |
| 93 | * Alan Cox : Outgoing firewall on build_xmit |
| 94 | * A.N.Kuznetsov : IP_OPTIONS support throughout the kernel |
| 95 | * Alan Cox : Multicast routing hooks |
| 96 | * Jos Vos : Do accounting *before* call_in_firewall |
| 97 | * Willy Konynenberg : Transparent proxying support |
| 98 | * |
| 99 | * To Fix: |
| 100 | * IP fragmentation wants rewriting cleanly. The RFC815 algorithm is much more efficient |
| 101 | * and could be made very efficient with the addition of some virtual memory hacks to permit |
| 102 | * the allocation of a buffer that can then be 'grown' by twiddling page tables. |
| 103 | * Output fragmentation wants updating along with the buffer management to use a single |
| 104 | * interleaved copy algorithm so that fragmenting has a one copy overhead. Actual packet |
| 105 | * output should probably do its own fragmentation at the UDP/RAW layer. TCP shouldn't cause |
| 106 | * fragmentation anyway. |
| 107 | */ |
| 108 | |
| 109 | #define pr_fmt(fmt) "IPv4: " fmt |
| 110 | |
| 111 | #include <linux/module.h> |
| 112 | #include <linux/types.h> |
| 113 | #include <linux/kernel.h> |
| 114 | #include <linux/string.h> |
| 115 | #include <linux/errno.h> |
| 116 | #include <linux/slab.h> |
| 117 | |
| 118 | #include <linux/net.h> |
| 119 | #include <linux/socket.h> |
| 120 | #include <linux/sockios.h> |
| 121 | #include <linux/in.h> |
| 122 | #include <linux/inet.h> |
| 123 | #include <linux/inetdevice.h> |
| 124 | #include <linux/netdevice.h> |
| 125 | #include <linux/etherdevice.h> |
| 126 | #include <linux/indirect_call_wrapper.h> |
| 127 | |
| 128 | #include <net/snmp.h> |
| 129 | #include <net/ip.h> |
| 130 | #include <net/protocol.h> |
| 131 | #include <net/route.h> |
| 132 | #include <linux/skbuff.h> |
| 133 | #include <net/sock.h> |
| 134 | #include <net/arp.h> |
| 135 | #include <net/icmp.h> |
| 136 | #include <net/raw.h> |
| 137 | #include <net/checksum.h> |
| 138 | #include <net/inet_ecn.h> |
| 139 | #include <linux/netfilter_ipv4.h> |
| 140 | #include <net/xfrm.h> |
| 141 | #include <linux/mroute.h> |
| 142 | #include <linux/netlink.h> |
| 143 | #include <net/dst_metadata.h> |
| 144 | |
| 145 | /* |
| 146 | * Process Router Attention IP option (RFC 2113) |
| 147 | */ |
| 148 | bool ip_call_ra_chain(struct sk_buff *skb) |
| 149 | { |
| 150 | struct ip_ra_chain *ra; |
| 151 | u8 protocol = ip_hdr(skb)->protocol; |
| 152 | struct sock *last = NULL; |
| 153 | struct net_device *dev = skb->dev; |
| 154 | struct net *net = dev_net(dev); |
| 155 | |
| 156 | for (ra = rcu_dereference(net->ipv4.ra_chain); ra; ra = rcu_dereference(ra->next)) { |
| 157 | struct sock *sk = ra->sk; |
| 158 | |
| 159 | /* If socket is bound to an interface, only report |
| 160 | * the packet if it came from that interface. |
| 161 | */ |
| 162 | if (sk && inet_sk(sk)->inet_num == protocol && |
| 163 | (!sk->sk_bound_dev_if || |
| 164 | sk->sk_bound_dev_if == dev->ifindex)) { |
| 165 | if (ip_is_fragment(ip_hdr(skb))) { |
| 166 | if (ip_defrag(net, skb, IP_DEFRAG_CALL_RA_CHAIN)) |
| 167 | return true; |
| 168 | } |
| 169 | if (last) { |
| 170 | struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC); |
| 171 | if (skb2) |
| 172 | raw_rcv(last, skb2); |
| 173 | } |
| 174 | last = sk; |
| 175 | } |
| 176 | } |
| 177 | |
| 178 | if (last) { |
| 179 | raw_rcv(last, skb); |
| 180 | return true; |
| 181 | } |
| 182 | return false; |
| 183 | } |
| 184 | |
| 185 | INDIRECT_CALLABLE_DECLARE(int udp_rcv(struct sk_buff *)); |
| 186 | INDIRECT_CALLABLE_DECLARE(int tcp_v4_rcv(struct sk_buff *)); |
| 187 | void ip_protocol_deliver_rcu(struct net *net, struct sk_buff *skb, int protocol) |
| 188 | { |
| 189 | const struct net_protocol *ipprot; |
| 190 | int raw, ret; |
| 191 | |
| 192 | resubmit: |
| 193 | raw = raw_local_deliver(skb, protocol); |
| 194 | |
| 195 | ipprot = rcu_dereference(inet_protos[protocol]); |
| 196 | if (ipprot) { |
| 197 | if (!ipprot->no_policy) { |
| 198 | if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { |
| 199 | kfree_skb_reason(skb, |
| 200 | SKB_DROP_REASON_XFRM_POLICY); |
| 201 | return; |
| 202 | } |
| 203 | nf_reset_ct(skb); |
| 204 | } |
| 205 | ret = INDIRECT_CALL_2(ipprot->handler, tcp_v4_rcv, udp_rcv, |
| 206 | skb); |
| 207 | if (ret < 0) { |
| 208 | protocol = -ret; |
| 209 | goto resubmit; |
| 210 | } |
| 211 | __IP_INC_STATS(net, IPSTATS_MIB_INDELIVERS); |
| 212 | } else { |
| 213 | if (!raw) { |
| 214 | if (xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { |
| 215 | __IP_INC_STATS(net, IPSTATS_MIB_INUNKNOWNPROTOS); |
| 216 | icmp_send(skb, ICMP_DEST_UNREACH, |
| 217 | ICMP_PROT_UNREACH, 0); |
| 218 | } |
| 219 | kfree_skb_reason(skb, SKB_DROP_REASON_IP_NOPROTO); |
| 220 | } else { |
| 221 | __IP_INC_STATS(net, IPSTATS_MIB_INDELIVERS); |
| 222 | consume_skb(skb); |
| 223 | } |
| 224 | } |
| 225 | } |
| 226 | |
| 227 | static int ip_local_deliver_finish(struct net *net, struct sock *sk, struct sk_buff *skb) |
| 228 | { |
| 229 | skb_clear_delivery_time(skb); |
| 230 | __skb_pull(skb, skb_network_header_len(skb)); |
| 231 | |
| 232 | rcu_read_lock(); |
| 233 | ip_protocol_deliver_rcu(net, skb, ip_hdr(skb)->protocol); |
| 234 | rcu_read_unlock(); |
| 235 | |
| 236 | return 0; |
| 237 | } |
| 238 | |
| 239 | /* |
| 240 | * Deliver IP Packets to the higher protocol layers. |
| 241 | */ |
| 242 | int ip_local_deliver(struct sk_buff *skb) |
| 243 | { |
| 244 | /* |
| 245 | * Reassemble IP fragments. |
| 246 | */ |
| 247 | struct net *net = dev_net(skb->dev); |
| 248 | |
| 249 | if (ip_is_fragment(ip_hdr(skb))) { |
| 250 | if (ip_defrag(net, skb, IP_DEFRAG_LOCAL_DELIVER)) |
| 251 | return 0; |
| 252 | } |
| 253 | |
| 254 | return NF_HOOK(NFPROTO_IPV4, NF_INET_LOCAL_IN, |
| 255 | net, NULL, skb, skb->dev, NULL, |
| 256 | ip_local_deliver_finish); |
| 257 | } |
| 258 | EXPORT_SYMBOL(ip_local_deliver); |
| 259 | |
| 260 | static inline bool ip_rcv_options(struct sk_buff *skb, struct net_device *dev) |
| 261 | { |
| 262 | struct ip_options *opt; |
| 263 | const struct iphdr *iph; |
| 264 | |
| 265 | /* It looks as overkill, because not all |
| 266 | IP options require packet mangling. |
| 267 | But it is the easiest for now, especially taking |
| 268 | into account that combination of IP options |
| 269 | and running sniffer is extremely rare condition. |
| 270 | --ANK (980813) |
| 271 | */ |
| 272 | if (skb_cow(skb, skb_headroom(skb))) { |
| 273 | __IP_INC_STATS(dev_net(dev), IPSTATS_MIB_INDISCARDS); |
| 274 | goto drop; |
| 275 | } |
| 276 | |
| 277 | iph = ip_hdr(skb); |
| 278 | opt = &(IPCB(skb)->opt); |
| 279 | opt->optlen = iph->ihl*4 - sizeof(struct iphdr); |
| 280 | |
| 281 | if (ip_options_compile(dev_net(dev), opt, skb)) { |
| 282 | __IP_INC_STATS(dev_net(dev), IPSTATS_MIB_INHDRERRORS); |
| 283 | goto drop; |
| 284 | } |
| 285 | |
| 286 | if (unlikely(opt->srr)) { |
| 287 | struct in_device *in_dev = __in_dev_get_rcu(dev); |
| 288 | |
| 289 | if (in_dev) { |
| 290 | if (!IN_DEV_SOURCE_ROUTE(in_dev)) { |
| 291 | if (IN_DEV_LOG_MARTIANS(in_dev)) |
| 292 | net_info_ratelimited("source route option %pI4 -> %pI4\n", |
| 293 | &iph->saddr, |
| 294 | &iph->daddr); |
| 295 | goto drop; |
| 296 | } |
| 297 | } |
| 298 | |
| 299 | if (ip_options_rcv_srr(skb, dev)) |
| 300 | goto drop; |
| 301 | } |
| 302 | |
| 303 | return false; |
| 304 | drop: |
| 305 | return true; |
| 306 | } |
| 307 | |
| 308 | static bool ip_can_use_hint(const struct sk_buff *skb, const struct iphdr *iph, |
| 309 | const struct sk_buff *hint) |
| 310 | { |
| 311 | return hint && !skb_dst(skb) && ip_hdr(hint)->daddr == iph->daddr && |
| 312 | ip_hdr(hint)->tos == iph->tos; |
| 313 | } |
| 314 | |
| 315 | int tcp_v4_early_demux(struct sk_buff *skb); |
| 316 | int udp_v4_early_demux(struct sk_buff *skb); |
| 317 | static int ip_rcv_finish_core(struct net *net, struct sock *sk, |
| 318 | struct sk_buff *skb, struct net_device *dev, |
| 319 | const struct sk_buff *hint) |
| 320 | { |
| 321 | const struct iphdr *iph = ip_hdr(skb); |
| 322 | int err, drop_reason; |
| 323 | struct rtable *rt; |
| 324 | |
| 325 | drop_reason = SKB_DROP_REASON_NOT_SPECIFIED; |
| 326 | |
| 327 | if (ip_can_use_hint(skb, iph, hint)) { |
| 328 | err = ip_route_use_hint(skb, iph->daddr, iph->saddr, iph->tos, |
| 329 | dev, hint); |
| 330 | if (unlikely(err)) |
| 331 | goto drop_error; |
| 332 | } |
| 333 | |
| 334 | if (READ_ONCE(net->ipv4.sysctl_ip_early_demux) && |
| 335 | !skb_dst(skb) && |
| 336 | !skb->sk && |
| 337 | !ip_is_fragment(iph)) { |
| 338 | switch (iph->protocol) { |
| 339 | case IPPROTO_TCP: |
| 340 | if (READ_ONCE(net->ipv4.sysctl_tcp_early_demux)) { |
| 341 | tcp_v4_early_demux(skb); |
| 342 | |
| 343 | /* must reload iph, skb->head might have changed */ |
| 344 | iph = ip_hdr(skb); |
| 345 | } |
| 346 | break; |
| 347 | case IPPROTO_UDP: |
| 348 | if (READ_ONCE(net->ipv4.sysctl_udp_early_demux)) { |
| 349 | err = udp_v4_early_demux(skb); |
| 350 | if (unlikely(err)) |
| 351 | goto drop_error; |
| 352 | |
| 353 | /* must reload iph, skb->head might have changed */ |
| 354 | iph = ip_hdr(skb); |
| 355 | } |
| 356 | break; |
| 357 | } |
| 358 | } |
| 359 | |
| 360 | /* |
| 361 | * Initialise the virtual path cache for the packet. It describes |
| 362 | * how the packet travels inside Linux networking. |
| 363 | */ |
| 364 | if (!skb_valid_dst(skb)) { |
| 365 | err = ip_route_input_noref(skb, iph->daddr, iph->saddr, |
| 366 | iph->tos, dev); |
| 367 | if (unlikely(err)) |
| 368 | goto drop_error; |
| 369 | } else { |
| 370 | struct in_device *in_dev = __in_dev_get_rcu(dev); |
| 371 | |
| 372 | if (in_dev && IN_DEV_ORCONF(in_dev, NOPOLICY)) |
| 373 | IPCB(skb)->flags |= IPSKB_NOPOLICY; |
| 374 | } |
| 375 | |
| 376 | #ifdef CONFIG_IP_ROUTE_CLASSID |
| 377 | if (unlikely(skb_dst(skb)->tclassid)) { |
| 378 | struct ip_rt_acct *st = this_cpu_ptr(ip_rt_acct); |
| 379 | u32 idx = skb_dst(skb)->tclassid; |
| 380 | st[idx&0xFF].o_packets++; |
| 381 | st[idx&0xFF].o_bytes += skb->len; |
| 382 | st[(idx>>16)&0xFF].i_packets++; |
| 383 | st[(idx>>16)&0xFF].i_bytes += skb->len; |
| 384 | } |
| 385 | #endif |
| 386 | |
| 387 | if (iph->ihl > 5 && ip_rcv_options(skb, dev)) |
| 388 | goto drop; |
| 389 | |
| 390 | rt = skb_rtable(skb); |
| 391 | if (rt->rt_type == RTN_MULTICAST) { |
| 392 | __IP_UPD_PO_STATS(net, IPSTATS_MIB_INMCAST, skb->len); |
| 393 | } else if (rt->rt_type == RTN_BROADCAST) { |
| 394 | __IP_UPD_PO_STATS(net, IPSTATS_MIB_INBCAST, skb->len); |
| 395 | } else if (skb->pkt_type == PACKET_BROADCAST || |
| 396 | skb->pkt_type == PACKET_MULTICAST) { |
| 397 | struct in_device *in_dev = __in_dev_get_rcu(dev); |
| 398 | |
| 399 | /* RFC 1122 3.3.6: |
| 400 | * |
| 401 | * When a host sends a datagram to a link-layer broadcast |
| 402 | * address, the IP destination address MUST be a legal IP |
| 403 | * broadcast or IP multicast address. |
| 404 | * |
| 405 | * A host SHOULD silently discard a datagram that is received |
| 406 | * via a link-layer broadcast (see Section 2.4) but does not |
| 407 | * specify an IP multicast or broadcast destination address. |
| 408 | * |
| 409 | * This doesn't explicitly say L2 *broadcast*, but broadcast is |
| 410 | * in a way a form of multicast and the most common use case for |
| 411 | * this is 802.11 protecting against cross-station spoofing (the |
| 412 | * so-called "hole-196" attack) so do it for both. |
| 413 | */ |
| 414 | if (in_dev && |
| 415 | IN_DEV_ORCONF(in_dev, DROP_UNICAST_IN_L2_MULTICAST)) { |
| 416 | drop_reason = SKB_DROP_REASON_UNICAST_IN_L2_MULTICAST; |
| 417 | goto drop; |
| 418 | } |
| 419 | } |
| 420 | |
| 421 | return NET_RX_SUCCESS; |
| 422 | |
| 423 | drop: |
| 424 | kfree_skb_reason(skb, drop_reason); |
| 425 | return NET_RX_DROP; |
| 426 | |
| 427 | drop_error: |
| 428 | if (err == -EXDEV) { |
| 429 | drop_reason = SKB_DROP_REASON_IP_RPFILTER; |
| 430 | __NET_INC_STATS(net, LINUX_MIB_IPRPFILTER); |
| 431 | } |
| 432 | goto drop; |
| 433 | } |
| 434 | |
| 435 | static int ip_rcv_finish(struct net *net, struct sock *sk, struct sk_buff *skb) |
| 436 | { |
| 437 | struct net_device *dev = skb->dev; |
| 438 | int ret; |
| 439 | |
| 440 | /* if ingress device is enslaved to an L3 master device pass the |
| 441 | * skb to its handler for processing |
| 442 | */ |
| 443 | skb = l3mdev_ip_rcv(skb); |
| 444 | if (!skb) |
| 445 | return NET_RX_SUCCESS; |
| 446 | |
| 447 | ret = ip_rcv_finish_core(net, sk, skb, dev, NULL); |
| 448 | if (ret != NET_RX_DROP) |
| 449 | ret = dst_input(skb); |
| 450 | return ret; |
| 451 | } |
| 452 | |
| 453 | /* |
| 454 | * Main IP Receive routine. |
| 455 | */ |
| 456 | static struct sk_buff *ip_rcv_core(struct sk_buff *skb, struct net *net) |
| 457 | { |
| 458 | const struct iphdr *iph; |
| 459 | int drop_reason; |
| 460 | u32 len; |
| 461 | |
| 462 | /* When the interface is in promisc. mode, drop all the crap |
| 463 | * that it receives, do not try to analyse it. |
| 464 | */ |
| 465 | if (skb->pkt_type == PACKET_OTHERHOST) { |
| 466 | dev_core_stats_rx_otherhost_dropped_inc(skb->dev); |
| 467 | drop_reason = SKB_DROP_REASON_OTHERHOST; |
| 468 | goto drop; |
| 469 | } |
| 470 | |
| 471 | __IP_UPD_PO_STATS(net, IPSTATS_MIB_IN, skb->len); |
| 472 | |
| 473 | skb = skb_share_check(skb, GFP_ATOMIC); |
| 474 | if (!skb) { |
| 475 | __IP_INC_STATS(net, IPSTATS_MIB_INDISCARDS); |
| 476 | goto out; |
| 477 | } |
| 478 | |
| 479 | drop_reason = SKB_DROP_REASON_NOT_SPECIFIED; |
| 480 | if (!pskb_may_pull(skb, sizeof(struct iphdr))) |
| 481 | goto inhdr_error; |
| 482 | |
| 483 | iph = ip_hdr(skb); |
| 484 | |
| 485 | /* |
| 486 | * RFC1122: 3.2.1.2 MUST silently discard any IP frame that fails the checksum. |
| 487 | * |
| 488 | * Is the datagram acceptable? |
| 489 | * |
| 490 | * 1. Length at least the size of an ip header |
| 491 | * 2. Version of 4 |
| 492 | * 3. Checksums correctly. [Speed optimisation for later, skip loopback checksums] |
| 493 | * 4. Doesn't have a bogus length |
| 494 | */ |
| 495 | |
| 496 | if (iph->ihl < 5 || iph->version != 4) |
| 497 | goto inhdr_error; |
| 498 | |
| 499 | BUILD_BUG_ON(IPSTATS_MIB_ECT1PKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_ECT_1); |
| 500 | BUILD_BUG_ON(IPSTATS_MIB_ECT0PKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_ECT_0); |
| 501 | BUILD_BUG_ON(IPSTATS_MIB_CEPKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_CE); |
| 502 | __IP_ADD_STATS(net, |
| 503 | IPSTATS_MIB_NOECTPKTS + (iph->tos & INET_ECN_MASK), |
| 504 | max_t(unsigned short, 1, skb_shinfo(skb)->gso_segs)); |
| 505 | |
| 506 | if (!pskb_may_pull(skb, iph->ihl*4)) |
| 507 | goto inhdr_error; |
| 508 | |
| 509 | iph = ip_hdr(skb); |
| 510 | |
| 511 | if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl))) |
| 512 | goto csum_error; |
| 513 | |
| 514 | len = iph_totlen(skb, iph); |
| 515 | if (skb->len < len) { |
| 516 | drop_reason = SKB_DROP_REASON_PKT_TOO_SMALL; |
| 517 | __IP_INC_STATS(net, IPSTATS_MIB_INTRUNCATEDPKTS); |
| 518 | goto drop; |
| 519 | } else if (len < (iph->ihl*4)) |
| 520 | goto inhdr_error; |
| 521 | |
| 522 | /* Our transport medium may have padded the buffer out. Now we know it |
| 523 | * is IP we can trim to the true length of the frame. |
| 524 | * Note this now means skb->len holds ntohs(iph->tot_len). |
| 525 | */ |
| 526 | if (pskb_trim_rcsum(skb, len)) { |
| 527 | __IP_INC_STATS(net, IPSTATS_MIB_INDISCARDS); |
| 528 | goto drop; |
| 529 | } |
| 530 | |
| 531 | iph = ip_hdr(skb); |
| 532 | skb->transport_header = skb->network_header + iph->ihl*4; |
| 533 | |
| 534 | /* Remove any debris in the socket control block */ |
| 535 | memset(IPCB(skb), 0, sizeof(struct inet_skb_parm)); |
| 536 | IPCB(skb)->iif = skb->skb_iif; |
| 537 | |
| 538 | /* Must drop socket now because of tproxy. */ |
| 539 | if (!skb_sk_is_prefetched(skb)) |
| 540 | skb_orphan(skb); |
| 541 | |
| 542 | return skb; |
| 543 | |
| 544 | csum_error: |
| 545 | drop_reason = SKB_DROP_REASON_IP_CSUM; |
| 546 | __IP_INC_STATS(net, IPSTATS_MIB_CSUMERRORS); |
| 547 | inhdr_error: |
| 548 | if (drop_reason == SKB_DROP_REASON_NOT_SPECIFIED) |
| 549 | drop_reason = SKB_DROP_REASON_IP_INHDR; |
| 550 | __IP_INC_STATS(net, IPSTATS_MIB_INHDRERRORS); |
| 551 | drop: |
| 552 | kfree_skb_reason(skb, drop_reason); |
| 553 | out: |
| 554 | return NULL; |
| 555 | } |
| 556 | |
| 557 | /* |
| 558 | * IP receive entry point |
| 559 | */ |
| 560 | int ip_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, |
| 561 | struct net_device *orig_dev) |
| 562 | { |
| 563 | struct net *net = dev_net(dev); |
| 564 | |
| 565 | skb = ip_rcv_core(skb, net); |
| 566 | if (skb == NULL) |
| 567 | return NET_RX_DROP; |
| 568 | |
| 569 | return NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, |
| 570 | net, NULL, skb, dev, NULL, |
| 571 | ip_rcv_finish); |
| 572 | } |
| 573 | |
| 574 | static void ip_sublist_rcv_finish(struct list_head *head) |
| 575 | { |
| 576 | struct sk_buff *skb, *next; |
| 577 | |
| 578 | list_for_each_entry_safe(skb, next, head, list) { |
| 579 | skb_list_del_init(skb); |
| 580 | dst_input(skb); |
| 581 | } |
| 582 | } |
| 583 | |
| 584 | static struct sk_buff *ip_extract_route_hint(const struct net *net, |
| 585 | struct sk_buff *skb, int rt_type) |
| 586 | { |
| 587 | if (fib4_has_custom_rules(net) || rt_type == RTN_BROADCAST || |
| 588 | IPCB(skb)->flags & IPSKB_MULTIPATH) |
| 589 | return NULL; |
| 590 | |
| 591 | return skb; |
| 592 | } |
| 593 | |
| 594 | static void ip_list_rcv_finish(struct net *net, struct sock *sk, |
| 595 | struct list_head *head) |
| 596 | { |
| 597 | struct sk_buff *skb, *next, *hint = NULL; |
| 598 | struct dst_entry *curr_dst = NULL; |
| 599 | LIST_HEAD(sublist); |
| 600 | |
| 601 | list_for_each_entry_safe(skb, next, head, list) { |
| 602 | struct net_device *dev = skb->dev; |
| 603 | struct dst_entry *dst; |
| 604 | |
| 605 | skb_list_del_init(skb); |
| 606 | /* if ingress device is enslaved to an L3 master device pass the |
| 607 | * skb to its handler for processing |
| 608 | */ |
| 609 | skb = l3mdev_ip_rcv(skb); |
| 610 | if (!skb) |
| 611 | continue; |
| 612 | if (ip_rcv_finish_core(net, sk, skb, dev, hint) == NET_RX_DROP) |
| 613 | continue; |
| 614 | |
| 615 | dst = skb_dst(skb); |
| 616 | if (curr_dst != dst) { |
| 617 | hint = ip_extract_route_hint(net, skb, |
| 618 | dst_rtable(dst)->rt_type); |
| 619 | |
| 620 | /* dispatch old sublist */ |
| 621 | if (!list_empty(&sublist)) |
| 622 | ip_sublist_rcv_finish(&sublist); |
| 623 | /* start new sublist */ |
| 624 | INIT_LIST_HEAD(&sublist); |
| 625 | curr_dst = dst; |
| 626 | } |
| 627 | list_add_tail(&skb->list, &sublist); |
| 628 | } |
| 629 | /* dispatch final sublist */ |
| 630 | ip_sublist_rcv_finish(&sublist); |
| 631 | } |
| 632 | |
| 633 | static void ip_sublist_rcv(struct list_head *head, struct net_device *dev, |
| 634 | struct net *net) |
| 635 | { |
| 636 | NF_HOOK_LIST(NFPROTO_IPV4, NF_INET_PRE_ROUTING, net, NULL, |
| 637 | head, dev, NULL, ip_rcv_finish); |
| 638 | ip_list_rcv_finish(net, NULL, head); |
| 639 | } |
| 640 | |
| 641 | /* Receive a list of IP packets */ |
| 642 | void ip_list_rcv(struct list_head *head, struct packet_type *pt, |
| 643 | struct net_device *orig_dev) |
| 644 | { |
| 645 | struct net_device *curr_dev = NULL; |
| 646 | struct net *curr_net = NULL; |
| 647 | struct sk_buff *skb, *next; |
| 648 | LIST_HEAD(sublist); |
| 649 | |
| 650 | list_for_each_entry_safe(skb, next, head, list) { |
| 651 | struct net_device *dev = skb->dev; |
| 652 | struct net *net = dev_net(dev); |
| 653 | |
| 654 | skb_list_del_init(skb); |
| 655 | skb = ip_rcv_core(skb, net); |
| 656 | if (skb == NULL) |
| 657 | continue; |
| 658 | |
| 659 | if (curr_dev != dev || curr_net != net) { |
| 660 | /* dispatch old sublist */ |
| 661 | if (!list_empty(&sublist)) |
| 662 | ip_sublist_rcv(&sublist, curr_dev, curr_net); |
| 663 | /* start new sublist */ |
| 664 | INIT_LIST_HEAD(&sublist); |
| 665 | curr_dev = dev; |
| 666 | curr_net = net; |
| 667 | } |
| 668 | list_add_tail(&skb->list, &sublist); |
| 669 | } |
| 670 | /* dispatch final sublist */ |
| 671 | if (!list_empty(&sublist)) |
| 672 | ip_sublist_rcv(&sublist, curr_dev, curr_net); |
| 673 | } |