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(skb); 200 return; 201 } 202 nf_reset_ct(skb); 203 } 204 ret = INDIRECT_CALL_2(ipprot->handler, tcp_v4_rcv, udp_rcv, 205 skb); 206 if (ret < 0) { 207 protocol = -ret; 208 goto resubmit; 209 } 210 __IP_INC_STATS(net, IPSTATS_MIB_INDELIVERS); 211 } else { 212 if (!raw) { 213 if (xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { 214 __IP_INC_STATS(net, IPSTATS_MIB_INUNKNOWNPROTOS); 215 icmp_send(skb, ICMP_DEST_UNREACH, 216 ICMP_PROT_UNREACH, 0); 217 } 218 kfree_skb(skb); 219 } else { 220 __IP_INC_STATS(net, IPSTATS_MIB_INDELIVERS); 221 consume_skb(skb); 222 } 223 } 224 } 225 226 static int ip_local_deliver_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 227 { 228 __skb_pull(skb, skb_network_header_len(skb)); 229 230 rcu_read_lock(); 231 ip_protocol_deliver_rcu(net, skb, ip_hdr(skb)->protocol); 232 rcu_read_unlock(); 233 234 return 0; 235 } 236 237 /* 238 * Deliver IP Packets to the higher protocol layers. 239 */ 240 int ip_local_deliver(struct sk_buff *skb) 241 { 242 /* 243 * Reassemble IP fragments. 244 */ 245 struct net *net = dev_net(skb->dev); 246 247 if (ip_is_fragment(ip_hdr(skb))) { 248 if (ip_defrag(net, skb, IP_DEFRAG_LOCAL_DELIVER)) 249 return 0; 250 } 251 252 return NF_HOOK(NFPROTO_IPV4, NF_INET_LOCAL_IN, 253 net, NULL, skb, skb->dev, NULL, 254 ip_local_deliver_finish); 255 } 256 EXPORT_SYMBOL(ip_local_deliver); 257 258 static inline bool ip_rcv_options(struct sk_buff *skb, struct net_device *dev) 259 { 260 struct ip_options *opt; 261 const struct iphdr *iph; 262 263 /* It looks as overkill, because not all 264 IP options require packet mangling. 265 But it is the easiest for now, especially taking 266 into account that combination of IP options 267 and running sniffer is extremely rare condition. 268 --ANK (980813) 269 */ 270 if (skb_cow(skb, skb_headroom(skb))) { 271 __IP_INC_STATS(dev_net(dev), IPSTATS_MIB_INDISCARDS); 272 goto drop; 273 } 274 275 iph = ip_hdr(skb); 276 opt = &(IPCB(skb)->opt); 277 opt->optlen = iph->ihl*4 - sizeof(struct iphdr); 278 279 if (ip_options_compile(dev_net(dev), opt, skb)) { 280 __IP_INC_STATS(dev_net(dev), IPSTATS_MIB_INHDRERRORS); 281 goto drop; 282 } 283 284 if (unlikely(opt->srr)) { 285 struct in_device *in_dev = __in_dev_get_rcu(dev); 286 287 if (in_dev) { 288 if (!IN_DEV_SOURCE_ROUTE(in_dev)) { 289 if (IN_DEV_LOG_MARTIANS(in_dev)) 290 net_info_ratelimited("source route option %pI4 -> %pI4\n", 291 &iph->saddr, 292 &iph->daddr); 293 goto drop; 294 } 295 } 296 297 if (ip_options_rcv_srr(skb, dev)) 298 goto drop; 299 } 300 301 return false; 302 drop: 303 return true; 304 } 305 306 static bool ip_can_use_hint(const struct sk_buff *skb, const struct iphdr *iph, 307 const struct sk_buff *hint) 308 { 309 return hint && !skb_dst(skb) && ip_hdr(hint)->daddr == iph->daddr && 310 ip_hdr(hint)->tos == iph->tos; 311 } 312 313 INDIRECT_CALLABLE_DECLARE(int udp_v4_early_demux(struct sk_buff *)); 314 INDIRECT_CALLABLE_DECLARE(int tcp_v4_early_demux(struct sk_buff *)); 315 static int ip_rcv_finish_core(struct net *net, struct sock *sk, 316 struct sk_buff *skb, struct net_device *dev, 317 const struct sk_buff *hint) 318 { 319 const struct iphdr *iph = ip_hdr(skb); 320 int (*edemux)(struct sk_buff *skb); 321 struct rtable *rt; 322 int err; 323 324 if (ip_can_use_hint(skb, iph, hint)) { 325 err = ip_route_use_hint(skb, iph->daddr, iph->saddr, iph->tos, 326 dev, hint); 327 if (unlikely(err)) 328 goto drop_error; 329 } 330 331 if (net->ipv4.sysctl_ip_early_demux && 332 !skb_dst(skb) && 333 !skb->sk && 334 !ip_is_fragment(iph)) { 335 const struct net_protocol *ipprot; 336 int protocol = iph->protocol; 337 338 ipprot = rcu_dereference(inet_protos[protocol]); 339 if (ipprot && (edemux = READ_ONCE(ipprot->early_demux))) { 340 err = INDIRECT_CALL_2(edemux, tcp_v4_early_demux, 341 udp_v4_early_demux, skb); 342 if (unlikely(err)) 343 goto drop_error; 344 /* must reload iph, skb->head might have changed */ 345 iph = ip_hdr(skb); 346 } 347 } 348 349 /* 350 * Initialise the virtual path cache for the packet. It describes 351 * how the packet travels inside Linux networking. 352 */ 353 if (!skb_valid_dst(skb)) { 354 err = ip_route_input_noref(skb, iph->daddr, iph->saddr, 355 iph->tos, dev); 356 if (unlikely(err)) 357 goto drop_error; 358 } 359 360 #ifdef CONFIG_IP_ROUTE_CLASSID 361 if (unlikely(skb_dst(skb)->tclassid)) { 362 struct ip_rt_acct *st = this_cpu_ptr(ip_rt_acct); 363 u32 idx = skb_dst(skb)->tclassid; 364 st[idx&0xFF].o_packets++; 365 st[idx&0xFF].o_bytes += skb->len; 366 st[(idx>>16)&0xFF].i_packets++; 367 st[(idx>>16)&0xFF].i_bytes += skb->len; 368 } 369 #endif 370 371 if (iph->ihl > 5 && ip_rcv_options(skb, dev)) 372 goto drop; 373 374 rt = skb_rtable(skb); 375 if (rt->rt_type == RTN_MULTICAST) { 376 __IP_UPD_PO_STATS(net, IPSTATS_MIB_INMCAST, skb->len); 377 } else if (rt->rt_type == RTN_BROADCAST) { 378 __IP_UPD_PO_STATS(net, IPSTATS_MIB_INBCAST, skb->len); 379 } else if (skb->pkt_type == PACKET_BROADCAST || 380 skb->pkt_type == PACKET_MULTICAST) { 381 struct in_device *in_dev = __in_dev_get_rcu(dev); 382 383 /* RFC 1122 3.3.6: 384 * 385 * When a host sends a datagram to a link-layer broadcast 386 * address, the IP destination address MUST be a legal IP 387 * broadcast or IP multicast address. 388 * 389 * A host SHOULD silently discard a datagram that is received 390 * via a link-layer broadcast (see Section 2.4) but does not 391 * specify an IP multicast or broadcast destination address. 392 * 393 * This doesn't explicitly say L2 *broadcast*, but broadcast is 394 * in a way a form of multicast and the most common use case for 395 * this is 802.11 protecting against cross-station spoofing (the 396 * so-called "hole-196" attack) so do it for both. 397 */ 398 if (in_dev && 399 IN_DEV_ORCONF(in_dev, DROP_UNICAST_IN_L2_MULTICAST)) 400 goto drop; 401 } 402 403 return NET_RX_SUCCESS; 404 405 drop: 406 kfree_skb(skb); 407 return NET_RX_DROP; 408 409 drop_error: 410 if (err == -EXDEV) 411 __NET_INC_STATS(net, LINUX_MIB_IPRPFILTER); 412 goto drop; 413 } 414 415 static int ip_rcv_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 416 { 417 struct net_device *dev = skb->dev; 418 int ret; 419 420 /* if ingress device is enslaved to an L3 master device pass the 421 * skb to its handler for processing 422 */ 423 skb = l3mdev_ip_rcv(skb); 424 if (!skb) 425 return NET_RX_SUCCESS; 426 427 ret = ip_rcv_finish_core(net, sk, skb, dev, NULL); 428 if (ret != NET_RX_DROP) 429 ret = dst_input(skb); 430 return ret; 431 } 432 433 /* 434 * Main IP Receive routine. 435 */ 436 static struct sk_buff *ip_rcv_core(struct sk_buff *skb, struct net *net) 437 { 438 const struct iphdr *iph; 439 u32 len; 440 441 /* When the interface is in promisc. mode, drop all the crap 442 * that it receives, do not try to analyse it. 443 */ 444 if (skb->pkt_type == PACKET_OTHERHOST) 445 goto drop; 446 447 __IP_UPD_PO_STATS(net, IPSTATS_MIB_IN, skb->len); 448 449 skb = skb_share_check(skb, GFP_ATOMIC); 450 if (!skb) { 451 __IP_INC_STATS(net, IPSTATS_MIB_INDISCARDS); 452 goto out; 453 } 454 455 if (!pskb_may_pull(skb, sizeof(struct iphdr))) 456 goto inhdr_error; 457 458 iph = ip_hdr(skb); 459 460 /* 461 * RFC1122: 3.2.1.2 MUST silently discard any IP frame that fails the checksum. 462 * 463 * Is the datagram acceptable? 464 * 465 * 1. Length at least the size of an ip header 466 * 2. Version of 4 467 * 3. Checksums correctly. [Speed optimisation for later, skip loopback checksums] 468 * 4. Doesn't have a bogus length 469 */ 470 471 if (iph->ihl < 5 || iph->version != 4) 472 goto inhdr_error; 473 474 BUILD_BUG_ON(IPSTATS_MIB_ECT1PKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_ECT_1); 475 BUILD_BUG_ON(IPSTATS_MIB_ECT0PKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_ECT_0); 476 BUILD_BUG_ON(IPSTATS_MIB_CEPKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_CE); 477 __IP_ADD_STATS(net, 478 IPSTATS_MIB_NOECTPKTS + (iph->tos & INET_ECN_MASK), 479 max_t(unsigned short, 1, skb_shinfo(skb)->gso_segs)); 480 481 if (!pskb_may_pull(skb, iph->ihl*4)) 482 goto inhdr_error; 483 484 iph = ip_hdr(skb); 485 486 if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl))) 487 goto csum_error; 488 489 len = ntohs(iph->tot_len); 490 if (skb->len < len) { 491 __IP_INC_STATS(net, IPSTATS_MIB_INTRUNCATEDPKTS); 492 goto drop; 493 } else if (len < (iph->ihl*4)) 494 goto inhdr_error; 495 496 /* Our transport medium may have padded the buffer out. Now we know it 497 * is IP we can trim to the true length of the frame. 498 * Note this now means skb->len holds ntohs(iph->tot_len). 499 */ 500 if (pskb_trim_rcsum(skb, len)) { 501 __IP_INC_STATS(net, IPSTATS_MIB_INDISCARDS); 502 goto drop; 503 } 504 505 iph = ip_hdr(skb); 506 skb->transport_header = skb->network_header + iph->ihl*4; 507 508 /* Remove any debris in the socket control block */ 509 memset(IPCB(skb), 0, sizeof(struct inet_skb_parm)); 510 IPCB(skb)->iif = skb->skb_iif; 511 512 /* Must drop socket now because of tproxy. */ 513 if (!skb_sk_is_prefetched(skb)) 514 skb_orphan(skb); 515 516 return skb; 517 518 csum_error: 519 __IP_INC_STATS(net, IPSTATS_MIB_CSUMERRORS); 520 inhdr_error: 521 __IP_INC_STATS(net, IPSTATS_MIB_INHDRERRORS); 522 drop: 523 kfree_skb(skb); 524 out: 525 return NULL; 526 } 527 528 /* 529 * IP receive entry point 530 */ 531 int ip_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, 532 struct net_device *orig_dev) 533 { 534 struct net *net = dev_net(dev); 535 536 skb = ip_rcv_core(skb, net); 537 if (skb == NULL) 538 return NET_RX_DROP; 539 540 return NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, 541 net, NULL, skb, dev, NULL, 542 ip_rcv_finish); 543 } 544 545 static void ip_sublist_rcv_finish(struct list_head *head) 546 { 547 struct sk_buff *skb, *next; 548 549 list_for_each_entry_safe(skb, next, head, list) { 550 skb_list_del_init(skb); 551 dst_input(skb); 552 } 553 } 554 555 static struct sk_buff *ip_extract_route_hint(const struct net *net, 556 struct sk_buff *skb, int rt_type) 557 { 558 if (fib4_has_custom_rules(net) || rt_type == RTN_BROADCAST) 559 return NULL; 560 561 return skb; 562 } 563 564 static void ip_list_rcv_finish(struct net *net, struct sock *sk, 565 struct list_head *head) 566 { 567 struct sk_buff *skb, *next, *hint = NULL; 568 struct dst_entry *curr_dst = NULL; 569 struct list_head sublist; 570 571 INIT_LIST_HEAD(&sublist); 572 list_for_each_entry_safe(skb, next, head, list) { 573 struct net_device *dev = skb->dev; 574 struct dst_entry *dst; 575 576 skb_list_del_init(skb); 577 /* if ingress device is enslaved to an L3 master device pass the 578 * skb to its handler for processing 579 */ 580 skb = l3mdev_ip_rcv(skb); 581 if (!skb) 582 continue; 583 if (ip_rcv_finish_core(net, sk, skb, dev, hint) == NET_RX_DROP) 584 continue; 585 586 dst = skb_dst(skb); 587 if (curr_dst != dst) { 588 hint = ip_extract_route_hint(net, skb, 589 ((struct rtable *)dst)->rt_type); 590 591 /* dispatch old sublist */ 592 if (!list_empty(&sublist)) 593 ip_sublist_rcv_finish(&sublist); 594 /* start new sublist */ 595 INIT_LIST_HEAD(&sublist); 596 curr_dst = dst; 597 } 598 list_add_tail(&skb->list, &sublist); 599 } 600 /* dispatch final sublist */ 601 ip_sublist_rcv_finish(&sublist); 602 } 603 604 static void ip_sublist_rcv(struct list_head *head, struct net_device *dev, 605 struct net *net) 606 { 607 NF_HOOK_LIST(NFPROTO_IPV4, NF_INET_PRE_ROUTING, net, NULL, 608 head, dev, NULL, ip_rcv_finish); 609 ip_list_rcv_finish(net, NULL, head); 610 } 611 612 /* Receive a list of IP packets */ 613 void ip_list_rcv(struct list_head *head, struct packet_type *pt, 614 struct net_device *orig_dev) 615 { 616 struct net_device *curr_dev = NULL; 617 struct net *curr_net = NULL; 618 struct sk_buff *skb, *next; 619 struct list_head sublist; 620 621 INIT_LIST_HEAD(&sublist); 622 list_for_each_entry_safe(skb, next, head, list) { 623 struct net_device *dev = skb->dev; 624 struct net *net = dev_net(dev); 625 626 skb_list_del_init(skb); 627 skb = ip_rcv_core(skb, net); 628 if (skb == NULL) 629 continue; 630 631 if (curr_dev != dev || curr_net != net) { 632 /* dispatch old sublist */ 633 if (!list_empty(&sublist)) 634 ip_sublist_rcv(&sublist, curr_dev, curr_net); 635 /* start new sublist */ 636 INIT_LIST_HEAD(&sublist); 637 curr_dev = dev; 638 curr_net = net; 639 } 640 list_add_tail(&skb->list, &sublist); 641 } 642 /* dispatch final sublist */ 643 if (!list_empty(&sublist)) 644 ip_sublist_rcv(&sublist, curr_dev, curr_net); 645 } 646