1 /* 2 * INET An implementation of the TCP/IP protocol suite for the LINUX 3 * operating system. INET is implemented using the BSD Socket 4 * interface as the means of communication with the user level. 5 * 6 * The Internet Protocol (IP) output module. 7 * 8 * Authors: Ross Biro 9 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> 10 * Donald Becker, <becker@super.org> 11 * Alan Cox, <Alan.Cox@linux.org> 12 * Richard Underwood 13 * Stefan Becker, <stefanb@yello.ping.de> 14 * Jorge Cwik, <jorge@laser.satlink.net> 15 * Arnt Gulbrandsen, <agulbra@nvg.unit.no> 16 * Hirokazu Takahashi, <taka@valinux.co.jp> 17 * 18 * See ip_input.c for original log 19 * 20 * Fixes: 21 * Alan Cox : Missing nonblock feature in ip_build_xmit. 22 * Mike Kilburn : htons() missing in ip_build_xmit. 23 * Bradford Johnson: Fix faulty handling of some frames when 24 * no route is found. 25 * Alexander Demenshin: Missing sk/skb free in ip_queue_xmit 26 * (in case if packet not accepted by 27 * output firewall rules) 28 * Mike McLagan : Routing by source 29 * Alexey Kuznetsov: use new route cache 30 * Andi Kleen: Fix broken PMTU recovery and remove 31 * some redundant tests. 32 * Vitaly E. Lavrov : Transparent proxy revived after year coma. 33 * Andi Kleen : Replace ip_reply with ip_send_reply. 34 * Andi Kleen : Split fast and slow ip_build_xmit path 35 * for decreased register pressure on x86 36 * and more readibility. 37 * Marc Boucher : When call_out_firewall returns FW_QUEUE, 38 * silently drop skb instead of failing with -EPERM. 39 * Detlev Wengorz : Copy protocol for fragments. 40 * Hirokazu Takahashi: HW checksumming for outgoing UDP 41 * datagrams. 42 * Hirokazu Takahashi: sendfile() on UDP works now. 43 */ 44 45 #include <asm/uaccess.h> 46 #include <linux/module.h> 47 #include <linux/types.h> 48 #include <linux/kernel.h> 49 #include <linux/mm.h> 50 #include <linux/string.h> 51 #include <linux/errno.h> 52 #include <linux/highmem.h> 53 #include <linux/slab.h> 54 55 #include <linux/socket.h> 56 #include <linux/sockios.h> 57 #include <linux/in.h> 58 #include <linux/inet.h> 59 #include <linux/netdevice.h> 60 #include <linux/etherdevice.h> 61 #include <linux/proc_fs.h> 62 #include <linux/stat.h> 63 #include <linux/init.h> 64 65 #include <net/snmp.h> 66 #include <net/ip.h> 67 #include <net/protocol.h> 68 #include <net/route.h> 69 #include <net/xfrm.h> 70 #include <linux/skbuff.h> 71 #include <net/sock.h> 72 #include <net/arp.h> 73 #include <net/icmp.h> 74 #include <net/checksum.h> 75 #include <net/inetpeer.h> 76 #include <linux/igmp.h> 77 #include <linux/netfilter_ipv4.h> 78 #include <linux/netfilter_bridge.h> 79 #include <linux/mroute.h> 80 #include <linux/netlink.h> 81 #include <linux/tcp.h> 82 83 int sysctl_ip_default_ttl __read_mostly = IPDEFTTL; 84 EXPORT_SYMBOL(sysctl_ip_default_ttl); 85 86 /* Generate a checksum for an outgoing IP datagram. */ 87 void ip_send_check(struct iphdr *iph) 88 { 89 iph->check = 0; 90 iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl); 91 } 92 EXPORT_SYMBOL(ip_send_check); 93 94 int __ip_local_out(struct sk_buff *skb) 95 { 96 struct iphdr *iph = ip_hdr(skb); 97 98 iph->tot_len = htons(skb->len); 99 ip_send_check(iph); 100 return nf_hook(NFPROTO_IPV4, NF_INET_LOCAL_OUT, skb, NULL, 101 skb_dst(skb)->dev, dst_output); 102 } 103 104 int ip_local_out_sk(struct sock *sk, struct sk_buff *skb) 105 { 106 int err; 107 108 err = __ip_local_out(skb); 109 if (likely(err == 1)) 110 err = dst_output_sk(sk, skb); 111 112 return err; 113 } 114 EXPORT_SYMBOL_GPL(ip_local_out_sk); 115 116 static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst) 117 { 118 int ttl = inet->uc_ttl; 119 120 if (ttl < 0) 121 ttl = ip4_dst_hoplimit(dst); 122 return ttl; 123 } 124 125 /* 126 * Add an ip header to a skbuff and send it out. 127 * 128 */ 129 int ip_build_and_send_pkt(struct sk_buff *skb, struct sock *sk, 130 __be32 saddr, __be32 daddr, struct ip_options_rcu *opt) 131 { 132 struct inet_sock *inet = inet_sk(sk); 133 struct rtable *rt = skb_rtable(skb); 134 struct iphdr *iph; 135 136 /* Build the IP header. */ 137 skb_push(skb, sizeof(struct iphdr) + (opt ? opt->opt.optlen : 0)); 138 skb_reset_network_header(skb); 139 iph = ip_hdr(skb); 140 iph->version = 4; 141 iph->ihl = 5; 142 iph->tos = inet->tos; 143 if (ip_dont_fragment(sk, &rt->dst)) 144 iph->frag_off = htons(IP_DF); 145 else 146 iph->frag_off = 0; 147 iph->ttl = ip_select_ttl(inet, &rt->dst); 148 iph->daddr = (opt && opt->opt.srr ? opt->opt.faddr : daddr); 149 iph->saddr = saddr; 150 iph->protocol = sk->sk_protocol; 151 ip_select_ident(skb, sk); 152 153 if (opt && opt->opt.optlen) { 154 iph->ihl += opt->opt.optlen>>2; 155 ip_options_build(skb, &opt->opt, daddr, rt, 0); 156 } 157 158 skb->priority = sk->sk_priority; 159 skb->mark = sk->sk_mark; 160 161 /* Send it out. */ 162 return ip_local_out(skb); 163 } 164 EXPORT_SYMBOL_GPL(ip_build_and_send_pkt); 165 166 static inline int ip_finish_output2(struct sk_buff *skb) 167 { 168 struct dst_entry *dst = skb_dst(skb); 169 struct rtable *rt = (struct rtable *)dst; 170 struct net_device *dev = dst->dev; 171 unsigned int hh_len = LL_RESERVED_SPACE(dev); 172 struct neighbour *neigh; 173 u32 nexthop; 174 175 if (rt->rt_type == RTN_MULTICAST) { 176 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUTMCAST, skb->len); 177 } else if (rt->rt_type == RTN_BROADCAST) 178 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUTBCAST, skb->len); 179 180 /* Be paranoid, rather than too clever. */ 181 if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) { 182 struct sk_buff *skb2; 183 184 skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev)); 185 if (skb2 == NULL) { 186 kfree_skb(skb); 187 return -ENOMEM; 188 } 189 if (skb->sk) 190 skb_set_owner_w(skb2, skb->sk); 191 consume_skb(skb); 192 skb = skb2; 193 } 194 195 rcu_read_lock_bh(); 196 nexthop = (__force u32) rt_nexthop(rt, ip_hdr(skb)->daddr); 197 neigh = __ipv4_neigh_lookup_noref(dev, nexthop); 198 if (unlikely(!neigh)) 199 neigh = __neigh_create(&arp_tbl, &nexthop, dev, false); 200 if (!IS_ERR(neigh)) { 201 int res = dst_neigh_output(dst, neigh, skb); 202 203 rcu_read_unlock_bh(); 204 return res; 205 } 206 rcu_read_unlock_bh(); 207 208 net_dbg_ratelimited("%s: No header cache and no neighbour!\n", 209 __func__); 210 kfree_skb(skb); 211 return -EINVAL; 212 } 213 214 static int ip_finish_output_gso(struct sk_buff *skb) 215 { 216 netdev_features_t features; 217 struct sk_buff *segs; 218 int ret = 0; 219 220 /* common case: locally created skb or seglen is <= mtu */ 221 if (((IPCB(skb)->flags & IPSKB_FORWARDED) == 0) || 222 skb_gso_network_seglen(skb) <= ip_skb_dst_mtu(skb)) 223 return ip_finish_output2(skb); 224 225 /* Slowpath - GSO segment length is exceeding the dst MTU. 226 * 227 * This can happen in two cases: 228 * 1) TCP GRO packet, DF bit not set 229 * 2) skb arrived via virtio-net, we thus get TSO/GSO skbs directly 230 * from host network stack. 231 */ 232 features = netif_skb_features(skb); 233 segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK); 234 if (IS_ERR_OR_NULL(segs)) { 235 kfree_skb(skb); 236 return -ENOMEM; 237 } 238 239 consume_skb(skb); 240 241 do { 242 struct sk_buff *nskb = segs->next; 243 int err; 244 245 segs->next = NULL; 246 err = ip_fragment(segs, ip_finish_output2); 247 248 if (err && ret == 0) 249 ret = err; 250 segs = nskb; 251 } while (segs); 252 253 return ret; 254 } 255 256 static int ip_finish_output(struct sk_buff *skb) 257 { 258 #if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM) 259 /* Policy lookup after SNAT yielded a new policy */ 260 if (skb_dst(skb)->xfrm != NULL) { 261 IPCB(skb)->flags |= IPSKB_REROUTED; 262 return dst_output(skb); 263 } 264 #endif 265 if (skb_is_gso(skb)) 266 return ip_finish_output_gso(skb); 267 268 if (skb->len > ip_skb_dst_mtu(skb)) 269 return ip_fragment(skb, ip_finish_output2); 270 271 return ip_finish_output2(skb); 272 } 273 274 int ip_mc_output(struct sock *sk, struct sk_buff *skb) 275 { 276 struct rtable *rt = skb_rtable(skb); 277 struct net_device *dev = rt->dst.dev; 278 279 /* 280 * If the indicated interface is up and running, send the packet. 281 */ 282 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len); 283 284 skb->dev = dev; 285 skb->protocol = htons(ETH_P_IP); 286 287 /* 288 * Multicasts are looped back for other local users 289 */ 290 291 if (rt->rt_flags&RTCF_MULTICAST) { 292 if (sk_mc_loop(sk) 293 #ifdef CONFIG_IP_MROUTE 294 /* Small optimization: do not loopback not local frames, 295 which returned after forwarding; they will be dropped 296 by ip_mr_input in any case. 297 Note, that local frames are looped back to be delivered 298 to local recipients. 299 300 This check is duplicated in ip_mr_input at the moment. 301 */ 302 && 303 ((rt->rt_flags & RTCF_LOCAL) || 304 !(IPCB(skb)->flags & IPSKB_FORWARDED)) 305 #endif 306 ) { 307 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC); 308 if (newskb) 309 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, 310 newskb, NULL, newskb->dev, 311 dev_loopback_xmit); 312 } 313 314 /* Multicasts with ttl 0 must not go beyond the host */ 315 316 if (ip_hdr(skb)->ttl == 0) { 317 kfree_skb(skb); 318 return 0; 319 } 320 } 321 322 if (rt->rt_flags&RTCF_BROADCAST) { 323 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC); 324 if (newskb) 325 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, newskb, 326 NULL, newskb->dev, dev_loopback_xmit); 327 } 328 329 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb, NULL, 330 skb->dev, ip_finish_output, 331 !(IPCB(skb)->flags & IPSKB_REROUTED)); 332 } 333 334 int ip_output(struct sock *sk, struct sk_buff *skb) 335 { 336 struct net_device *dev = skb_dst(skb)->dev; 337 338 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len); 339 340 skb->dev = dev; 341 skb->protocol = htons(ETH_P_IP); 342 343 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb, NULL, dev, 344 ip_finish_output, 345 !(IPCB(skb)->flags & IPSKB_REROUTED)); 346 } 347 348 /* 349 * copy saddr and daddr, possibly using 64bit load/stores 350 * Equivalent to : 351 * iph->saddr = fl4->saddr; 352 * iph->daddr = fl4->daddr; 353 */ 354 static void ip_copy_addrs(struct iphdr *iph, const struct flowi4 *fl4) 355 { 356 BUILD_BUG_ON(offsetof(typeof(*fl4), daddr) != 357 offsetof(typeof(*fl4), saddr) + sizeof(fl4->saddr)); 358 memcpy(&iph->saddr, &fl4->saddr, 359 sizeof(fl4->saddr) + sizeof(fl4->daddr)); 360 } 361 362 /* Note: skb->sk can be different from sk, in case of tunnels */ 363 int ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl) 364 { 365 struct inet_sock *inet = inet_sk(sk); 366 struct ip_options_rcu *inet_opt; 367 struct flowi4 *fl4; 368 struct rtable *rt; 369 struct iphdr *iph; 370 int res; 371 372 /* Skip all of this if the packet is already routed, 373 * f.e. by something like SCTP. 374 */ 375 rcu_read_lock(); 376 inet_opt = rcu_dereference(inet->inet_opt); 377 fl4 = &fl->u.ip4; 378 rt = skb_rtable(skb); 379 if (rt != NULL) 380 goto packet_routed; 381 382 /* Make sure we can route this packet. */ 383 rt = (struct rtable *)__sk_dst_check(sk, 0); 384 if (rt == NULL) { 385 __be32 daddr; 386 387 /* Use correct destination address if we have options. */ 388 daddr = inet->inet_daddr; 389 if (inet_opt && inet_opt->opt.srr) 390 daddr = inet_opt->opt.faddr; 391 392 /* If this fails, retransmit mechanism of transport layer will 393 * keep trying until route appears or the connection times 394 * itself out. 395 */ 396 rt = ip_route_output_ports(sock_net(sk), fl4, sk, 397 daddr, inet->inet_saddr, 398 inet->inet_dport, 399 inet->inet_sport, 400 sk->sk_protocol, 401 RT_CONN_FLAGS(sk), 402 sk->sk_bound_dev_if); 403 if (IS_ERR(rt)) 404 goto no_route; 405 sk_setup_caps(sk, &rt->dst); 406 } 407 skb_dst_set_noref(skb, &rt->dst); 408 409 packet_routed: 410 if (inet_opt && inet_opt->opt.is_strictroute && rt->rt_uses_gateway) 411 goto no_route; 412 413 /* OK, we know where to send it, allocate and build IP header. */ 414 skb_push(skb, sizeof(struct iphdr) + (inet_opt ? inet_opt->opt.optlen : 0)); 415 skb_reset_network_header(skb); 416 iph = ip_hdr(skb); 417 *((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (inet->tos & 0xff)); 418 if (ip_dont_fragment(sk, &rt->dst) && !skb->ignore_df) 419 iph->frag_off = htons(IP_DF); 420 else 421 iph->frag_off = 0; 422 iph->ttl = ip_select_ttl(inet, &rt->dst); 423 iph->protocol = sk->sk_protocol; 424 ip_copy_addrs(iph, fl4); 425 426 /* Transport layer set skb->h.foo itself. */ 427 428 if (inet_opt && inet_opt->opt.optlen) { 429 iph->ihl += inet_opt->opt.optlen >> 2; 430 ip_options_build(skb, &inet_opt->opt, inet->inet_daddr, rt, 0); 431 } 432 433 ip_select_ident_segs(skb, sk, skb_shinfo(skb)->gso_segs ?: 1); 434 435 /* TODO : should we use skb->sk here instead of sk ? */ 436 skb->priority = sk->sk_priority; 437 skb->mark = sk->sk_mark; 438 439 res = ip_local_out(skb); 440 rcu_read_unlock(); 441 return res; 442 443 no_route: 444 rcu_read_unlock(); 445 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES); 446 kfree_skb(skb); 447 return -EHOSTUNREACH; 448 } 449 EXPORT_SYMBOL(ip_queue_xmit); 450 451 452 static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from) 453 { 454 to->pkt_type = from->pkt_type; 455 to->priority = from->priority; 456 to->protocol = from->protocol; 457 skb_dst_drop(to); 458 skb_dst_copy(to, from); 459 to->dev = from->dev; 460 to->mark = from->mark; 461 462 /* Copy the flags to each fragment. */ 463 IPCB(to)->flags = IPCB(from)->flags; 464 465 #ifdef CONFIG_NET_SCHED 466 to->tc_index = from->tc_index; 467 #endif 468 nf_copy(to, from); 469 #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE) 470 to->ipvs_property = from->ipvs_property; 471 #endif 472 skb_copy_secmark(to, from); 473 } 474 475 /* 476 * This IP datagram is too large to be sent in one piece. Break it up into 477 * smaller pieces (each of size equal to IP header plus 478 * a block of the data of the original IP data part) that will yet fit in a 479 * single device frame, and queue such a frame for sending. 480 */ 481 482 int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *)) 483 { 484 struct iphdr *iph; 485 int ptr; 486 struct net_device *dev; 487 struct sk_buff *skb2; 488 unsigned int mtu, hlen, left, len, ll_rs; 489 int offset; 490 __be16 not_last_frag; 491 struct rtable *rt = skb_rtable(skb); 492 int err = 0; 493 494 dev = rt->dst.dev; 495 496 /* 497 * Point into the IP datagram header. 498 */ 499 500 iph = ip_hdr(skb); 501 502 mtu = ip_skb_dst_mtu(skb); 503 if (unlikely(((iph->frag_off & htons(IP_DF)) && !skb->ignore_df) || 504 (IPCB(skb)->frag_max_size && 505 IPCB(skb)->frag_max_size > mtu))) { 506 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); 507 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, 508 htonl(mtu)); 509 kfree_skb(skb); 510 return -EMSGSIZE; 511 } 512 513 /* 514 * Setup starting values. 515 */ 516 517 hlen = iph->ihl * 4; 518 mtu = mtu - hlen; /* Size of data space */ 519 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) 520 if (skb->nf_bridge) 521 mtu -= nf_bridge_mtu_reduction(skb); 522 #endif 523 IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE; 524 525 /* When frag_list is given, use it. First, check its validity: 526 * some transformers could create wrong frag_list or break existing 527 * one, it is not prohibited. In this case fall back to copying. 528 * 529 * LATER: this step can be merged to real generation of fragments, 530 * we can switch to copy when see the first bad fragment. 531 */ 532 if (skb_has_frag_list(skb)) { 533 struct sk_buff *frag, *frag2; 534 int first_len = skb_pagelen(skb); 535 536 if (first_len - hlen > mtu || 537 ((first_len - hlen) & 7) || 538 ip_is_fragment(iph) || 539 skb_cloned(skb)) 540 goto slow_path; 541 542 skb_walk_frags(skb, frag) { 543 /* Correct geometry. */ 544 if (frag->len > mtu || 545 ((frag->len & 7) && frag->next) || 546 skb_headroom(frag) < hlen) 547 goto slow_path_clean; 548 549 /* Partially cloned skb? */ 550 if (skb_shared(frag)) 551 goto slow_path_clean; 552 553 BUG_ON(frag->sk); 554 if (skb->sk) { 555 frag->sk = skb->sk; 556 frag->destructor = sock_wfree; 557 } 558 skb->truesize -= frag->truesize; 559 } 560 561 /* Everything is OK. Generate! */ 562 563 err = 0; 564 offset = 0; 565 frag = skb_shinfo(skb)->frag_list; 566 skb_frag_list_init(skb); 567 skb->data_len = first_len - skb_headlen(skb); 568 skb->len = first_len; 569 iph->tot_len = htons(first_len); 570 iph->frag_off = htons(IP_MF); 571 ip_send_check(iph); 572 573 for (;;) { 574 /* Prepare header of the next frame, 575 * before previous one went down. */ 576 if (frag) { 577 frag->ip_summed = CHECKSUM_NONE; 578 skb_reset_transport_header(frag); 579 __skb_push(frag, hlen); 580 skb_reset_network_header(frag); 581 memcpy(skb_network_header(frag), iph, hlen); 582 iph = ip_hdr(frag); 583 iph->tot_len = htons(frag->len); 584 ip_copy_metadata(frag, skb); 585 if (offset == 0) 586 ip_options_fragment(frag); 587 offset += skb->len - hlen; 588 iph->frag_off = htons(offset>>3); 589 if (frag->next != NULL) 590 iph->frag_off |= htons(IP_MF); 591 /* Ready, complete checksum */ 592 ip_send_check(iph); 593 } 594 595 err = output(skb); 596 597 if (!err) 598 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES); 599 if (err || !frag) 600 break; 601 602 skb = frag; 603 frag = skb->next; 604 skb->next = NULL; 605 } 606 607 if (err == 0) { 608 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS); 609 return 0; 610 } 611 612 while (frag) { 613 skb = frag->next; 614 kfree_skb(frag); 615 frag = skb; 616 } 617 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); 618 return err; 619 620 slow_path_clean: 621 skb_walk_frags(skb, frag2) { 622 if (frag2 == frag) 623 break; 624 frag2->sk = NULL; 625 frag2->destructor = NULL; 626 skb->truesize += frag2->truesize; 627 } 628 } 629 630 slow_path: 631 /* for offloaded checksums cleanup checksum before fragmentation */ 632 if ((skb->ip_summed == CHECKSUM_PARTIAL) && skb_checksum_help(skb)) 633 goto fail; 634 iph = ip_hdr(skb); 635 636 left = skb->len - hlen; /* Space per frame */ 637 ptr = hlen; /* Where to start from */ 638 639 /* for bridged IP traffic encapsulated inside f.e. a vlan header, 640 * we need to make room for the encapsulating header 641 */ 642 ll_rs = LL_RESERVED_SPACE_EXTRA(rt->dst.dev, nf_bridge_pad(skb)); 643 644 /* 645 * Fragment the datagram. 646 */ 647 648 offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3; 649 not_last_frag = iph->frag_off & htons(IP_MF); 650 651 /* 652 * Keep copying data until we run out. 653 */ 654 655 while (left > 0) { 656 len = left; 657 /* IF: it doesn't fit, use 'mtu' - the data space left */ 658 if (len > mtu) 659 len = mtu; 660 /* IF: we are not sending up to and including the packet end 661 then align the next start on an eight byte boundary */ 662 if (len < left) { 663 len &= ~7; 664 } 665 666 /* Allocate buffer */ 667 skb2 = alloc_skb(len + hlen + ll_rs, GFP_ATOMIC); 668 if (!skb2) { 669 err = -ENOMEM; 670 goto fail; 671 } 672 673 /* 674 * Set up data on packet 675 */ 676 677 ip_copy_metadata(skb2, skb); 678 skb_reserve(skb2, ll_rs); 679 skb_put(skb2, len + hlen); 680 skb_reset_network_header(skb2); 681 skb2->transport_header = skb2->network_header + hlen; 682 683 /* 684 * Charge the memory for the fragment to any owner 685 * it might possess 686 */ 687 688 if (skb->sk) 689 skb_set_owner_w(skb2, skb->sk); 690 691 /* 692 * Copy the packet header into the new buffer. 693 */ 694 695 skb_copy_from_linear_data(skb, skb_network_header(skb2), hlen); 696 697 /* 698 * Copy a block of the IP datagram. 699 */ 700 if (skb_copy_bits(skb, ptr, skb_transport_header(skb2), len)) 701 BUG(); 702 left -= len; 703 704 /* 705 * Fill in the new header fields. 706 */ 707 iph = ip_hdr(skb2); 708 iph->frag_off = htons((offset >> 3)); 709 710 /* ANK: dirty, but effective trick. Upgrade options only if 711 * the segment to be fragmented was THE FIRST (otherwise, 712 * options are already fixed) and make it ONCE 713 * on the initial skb, so that all the following fragments 714 * will inherit fixed options. 715 */ 716 if (offset == 0) 717 ip_options_fragment(skb); 718 719 /* 720 * Added AC : If we are fragmenting a fragment that's not the 721 * last fragment then keep MF on each bit 722 */ 723 if (left > 0 || not_last_frag) 724 iph->frag_off |= htons(IP_MF); 725 ptr += len; 726 offset += len; 727 728 /* 729 * Put this fragment into the sending queue. 730 */ 731 iph->tot_len = htons(len + hlen); 732 733 ip_send_check(iph); 734 735 err = output(skb2); 736 if (err) 737 goto fail; 738 739 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES); 740 } 741 consume_skb(skb); 742 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS); 743 return err; 744 745 fail: 746 kfree_skb(skb); 747 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); 748 return err; 749 } 750 EXPORT_SYMBOL(ip_fragment); 751 752 int 753 ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb) 754 { 755 struct msghdr *msg = from; 756 757 if (skb->ip_summed == CHECKSUM_PARTIAL) { 758 if (copy_from_iter(to, len, &msg->msg_iter) != len) 759 return -EFAULT; 760 } else { 761 __wsum csum = 0; 762 if (csum_and_copy_from_iter(to, len, &csum, &msg->msg_iter) != len) 763 return -EFAULT; 764 skb->csum = csum_block_add(skb->csum, csum, odd); 765 } 766 return 0; 767 } 768 EXPORT_SYMBOL(ip_generic_getfrag); 769 770 static inline __wsum 771 csum_page(struct page *page, int offset, int copy) 772 { 773 char *kaddr; 774 __wsum csum; 775 kaddr = kmap(page); 776 csum = csum_partial(kaddr + offset, copy, 0); 777 kunmap(page); 778 return csum; 779 } 780 781 static inline int ip_ufo_append_data(struct sock *sk, 782 struct sk_buff_head *queue, 783 int getfrag(void *from, char *to, int offset, int len, 784 int odd, struct sk_buff *skb), 785 void *from, int length, int hh_len, int fragheaderlen, 786 int transhdrlen, int maxfraglen, unsigned int flags) 787 { 788 struct sk_buff *skb; 789 int err; 790 791 /* There is support for UDP fragmentation offload by network 792 * device, so create one single skb packet containing complete 793 * udp datagram 794 */ 795 if ((skb = skb_peek_tail(queue)) == NULL) { 796 skb = sock_alloc_send_skb(sk, 797 hh_len + fragheaderlen + transhdrlen + 20, 798 (flags & MSG_DONTWAIT), &err); 799 800 if (skb == NULL) 801 return err; 802 803 /* reserve space for Hardware header */ 804 skb_reserve(skb, hh_len); 805 806 /* create space for UDP/IP header */ 807 skb_put(skb, fragheaderlen + transhdrlen); 808 809 /* initialize network header pointer */ 810 skb_reset_network_header(skb); 811 812 /* initialize protocol header pointer */ 813 skb->transport_header = skb->network_header + fragheaderlen; 814 815 skb->csum = 0; 816 817 818 __skb_queue_tail(queue, skb); 819 } else if (skb_is_gso(skb)) { 820 goto append; 821 } 822 823 skb->ip_summed = CHECKSUM_PARTIAL; 824 /* specify the length of each IP datagram fragment */ 825 skb_shinfo(skb)->gso_size = maxfraglen - fragheaderlen; 826 skb_shinfo(skb)->gso_type = SKB_GSO_UDP; 827 828 append: 829 return skb_append_datato_frags(sk, skb, getfrag, from, 830 (length - transhdrlen)); 831 } 832 833 static int __ip_append_data(struct sock *sk, 834 struct flowi4 *fl4, 835 struct sk_buff_head *queue, 836 struct inet_cork *cork, 837 struct page_frag *pfrag, 838 int getfrag(void *from, char *to, int offset, 839 int len, int odd, struct sk_buff *skb), 840 void *from, int length, int transhdrlen, 841 unsigned int flags) 842 { 843 struct inet_sock *inet = inet_sk(sk); 844 struct sk_buff *skb; 845 846 struct ip_options *opt = cork->opt; 847 int hh_len; 848 int exthdrlen; 849 int mtu; 850 int copy; 851 int err; 852 int offset = 0; 853 unsigned int maxfraglen, fragheaderlen, maxnonfragsize; 854 int csummode = CHECKSUM_NONE; 855 struct rtable *rt = (struct rtable *)cork->dst; 856 u32 tskey = 0; 857 858 skb = skb_peek_tail(queue); 859 860 exthdrlen = !skb ? rt->dst.header_len : 0; 861 mtu = cork->fragsize; 862 if (cork->tx_flags & SKBTX_ANY_SW_TSTAMP && 863 sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID) 864 tskey = sk->sk_tskey++; 865 866 hh_len = LL_RESERVED_SPACE(rt->dst.dev); 867 868 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0); 869 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen; 870 maxnonfragsize = ip_sk_ignore_df(sk) ? 0xFFFF : mtu; 871 872 if (cork->length + length > maxnonfragsize - fragheaderlen) { 873 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport, 874 mtu - (opt ? opt->optlen : 0)); 875 return -EMSGSIZE; 876 } 877 878 /* 879 * transhdrlen > 0 means that this is the first fragment and we wish 880 * it won't be fragmented in the future. 881 */ 882 if (transhdrlen && 883 length + fragheaderlen <= mtu && 884 rt->dst.dev->features & NETIF_F_V4_CSUM && 885 !exthdrlen) 886 csummode = CHECKSUM_PARTIAL; 887 888 cork->length += length; 889 if (((length > mtu) || (skb && skb_is_gso(skb))) && 890 (sk->sk_protocol == IPPROTO_UDP) && 891 (rt->dst.dev->features & NETIF_F_UFO) && !rt->dst.header_len) { 892 err = ip_ufo_append_data(sk, queue, getfrag, from, length, 893 hh_len, fragheaderlen, transhdrlen, 894 maxfraglen, flags); 895 if (err) 896 goto error; 897 return 0; 898 } 899 900 /* So, what's going on in the loop below? 901 * 902 * We use calculated fragment length to generate chained skb, 903 * each of segments is IP fragment ready for sending to network after 904 * adding appropriate IP header. 905 */ 906 907 if (!skb) 908 goto alloc_new_skb; 909 910 while (length > 0) { 911 /* Check if the remaining data fits into current packet. */ 912 copy = mtu - skb->len; 913 if (copy < length) 914 copy = maxfraglen - skb->len; 915 if (copy <= 0) { 916 char *data; 917 unsigned int datalen; 918 unsigned int fraglen; 919 unsigned int fraggap; 920 unsigned int alloclen; 921 struct sk_buff *skb_prev; 922 alloc_new_skb: 923 skb_prev = skb; 924 if (skb_prev) 925 fraggap = skb_prev->len - maxfraglen; 926 else 927 fraggap = 0; 928 929 /* 930 * If remaining data exceeds the mtu, 931 * we know we need more fragment(s). 932 */ 933 datalen = length + fraggap; 934 if (datalen > mtu - fragheaderlen) 935 datalen = maxfraglen - fragheaderlen; 936 fraglen = datalen + fragheaderlen; 937 938 if ((flags & MSG_MORE) && 939 !(rt->dst.dev->features&NETIF_F_SG)) 940 alloclen = mtu; 941 else 942 alloclen = fraglen; 943 944 alloclen += exthdrlen; 945 946 /* The last fragment gets additional space at tail. 947 * Note, with MSG_MORE we overallocate on fragments, 948 * because we have no idea what fragment will be 949 * the last. 950 */ 951 if (datalen == length + fraggap) 952 alloclen += rt->dst.trailer_len; 953 954 if (transhdrlen) { 955 skb = sock_alloc_send_skb(sk, 956 alloclen + hh_len + 15, 957 (flags & MSG_DONTWAIT), &err); 958 } else { 959 skb = NULL; 960 if (atomic_read(&sk->sk_wmem_alloc) <= 961 2 * sk->sk_sndbuf) 962 skb = sock_wmalloc(sk, 963 alloclen + hh_len + 15, 1, 964 sk->sk_allocation); 965 if (unlikely(skb == NULL)) 966 err = -ENOBUFS; 967 } 968 if (skb == NULL) 969 goto error; 970 971 /* 972 * Fill in the control structures 973 */ 974 skb->ip_summed = csummode; 975 skb->csum = 0; 976 skb_reserve(skb, hh_len); 977 978 /* only the initial fragment is time stamped */ 979 skb_shinfo(skb)->tx_flags = cork->tx_flags; 980 cork->tx_flags = 0; 981 skb_shinfo(skb)->tskey = tskey; 982 tskey = 0; 983 984 /* 985 * Find where to start putting bytes. 986 */ 987 data = skb_put(skb, fraglen + exthdrlen); 988 skb_set_network_header(skb, exthdrlen); 989 skb->transport_header = (skb->network_header + 990 fragheaderlen); 991 data += fragheaderlen + exthdrlen; 992 993 if (fraggap) { 994 skb->csum = skb_copy_and_csum_bits( 995 skb_prev, maxfraglen, 996 data + transhdrlen, fraggap, 0); 997 skb_prev->csum = csum_sub(skb_prev->csum, 998 skb->csum); 999 data += fraggap; 1000 pskb_trim_unique(skb_prev, maxfraglen); 1001 } 1002 1003 copy = datalen - transhdrlen - fraggap; 1004 if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) { 1005 err = -EFAULT; 1006 kfree_skb(skb); 1007 goto error; 1008 } 1009 1010 offset += copy; 1011 length -= datalen - fraggap; 1012 transhdrlen = 0; 1013 exthdrlen = 0; 1014 csummode = CHECKSUM_NONE; 1015 1016 /* 1017 * Put the packet on the pending queue. 1018 */ 1019 __skb_queue_tail(queue, skb); 1020 continue; 1021 } 1022 1023 if (copy > length) 1024 copy = length; 1025 1026 if (!(rt->dst.dev->features&NETIF_F_SG)) { 1027 unsigned int off; 1028 1029 off = skb->len; 1030 if (getfrag(from, skb_put(skb, copy), 1031 offset, copy, off, skb) < 0) { 1032 __skb_trim(skb, off); 1033 err = -EFAULT; 1034 goto error; 1035 } 1036 } else { 1037 int i = skb_shinfo(skb)->nr_frags; 1038 1039 err = -ENOMEM; 1040 if (!sk_page_frag_refill(sk, pfrag)) 1041 goto error; 1042 1043 if (!skb_can_coalesce(skb, i, pfrag->page, 1044 pfrag->offset)) { 1045 err = -EMSGSIZE; 1046 if (i == MAX_SKB_FRAGS) 1047 goto error; 1048 1049 __skb_fill_page_desc(skb, i, pfrag->page, 1050 pfrag->offset, 0); 1051 skb_shinfo(skb)->nr_frags = ++i; 1052 get_page(pfrag->page); 1053 } 1054 copy = min_t(int, copy, pfrag->size - pfrag->offset); 1055 if (getfrag(from, 1056 page_address(pfrag->page) + pfrag->offset, 1057 offset, copy, skb->len, skb) < 0) 1058 goto error_efault; 1059 1060 pfrag->offset += copy; 1061 skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy); 1062 skb->len += copy; 1063 skb->data_len += copy; 1064 skb->truesize += copy; 1065 atomic_add(copy, &sk->sk_wmem_alloc); 1066 } 1067 offset += copy; 1068 length -= copy; 1069 } 1070 1071 return 0; 1072 1073 error_efault: 1074 err = -EFAULT; 1075 error: 1076 cork->length -= length; 1077 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS); 1078 return err; 1079 } 1080 1081 static int ip_setup_cork(struct sock *sk, struct inet_cork *cork, 1082 struct ipcm_cookie *ipc, struct rtable **rtp) 1083 { 1084 struct ip_options_rcu *opt; 1085 struct rtable *rt; 1086 1087 /* 1088 * setup for corking. 1089 */ 1090 opt = ipc->opt; 1091 if (opt) { 1092 if (cork->opt == NULL) { 1093 cork->opt = kmalloc(sizeof(struct ip_options) + 40, 1094 sk->sk_allocation); 1095 if (unlikely(cork->opt == NULL)) 1096 return -ENOBUFS; 1097 } 1098 memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen); 1099 cork->flags |= IPCORK_OPT; 1100 cork->addr = ipc->addr; 1101 } 1102 rt = *rtp; 1103 if (unlikely(!rt)) 1104 return -EFAULT; 1105 /* 1106 * We steal reference to this route, caller should not release it 1107 */ 1108 *rtp = NULL; 1109 cork->fragsize = ip_sk_use_pmtu(sk) ? 1110 dst_mtu(&rt->dst) : rt->dst.dev->mtu; 1111 cork->dst = &rt->dst; 1112 cork->length = 0; 1113 cork->ttl = ipc->ttl; 1114 cork->tos = ipc->tos; 1115 cork->priority = ipc->priority; 1116 cork->tx_flags = ipc->tx_flags; 1117 1118 return 0; 1119 } 1120 1121 /* 1122 * ip_append_data() and ip_append_page() can make one large IP datagram 1123 * from many pieces of data. Each pieces will be holded on the socket 1124 * until ip_push_pending_frames() is called. Each piece can be a page 1125 * or non-page data. 1126 * 1127 * Not only UDP, other transport protocols - e.g. raw sockets - can use 1128 * this interface potentially. 1129 * 1130 * LATER: length must be adjusted by pad at tail, when it is required. 1131 */ 1132 int ip_append_data(struct sock *sk, struct flowi4 *fl4, 1133 int getfrag(void *from, char *to, int offset, int len, 1134 int odd, struct sk_buff *skb), 1135 void *from, int length, int transhdrlen, 1136 struct ipcm_cookie *ipc, struct rtable **rtp, 1137 unsigned int flags) 1138 { 1139 struct inet_sock *inet = inet_sk(sk); 1140 int err; 1141 1142 if (flags&MSG_PROBE) 1143 return 0; 1144 1145 if (skb_queue_empty(&sk->sk_write_queue)) { 1146 err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp); 1147 if (err) 1148 return err; 1149 } else { 1150 transhdrlen = 0; 1151 } 1152 1153 return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base, 1154 sk_page_frag(sk), getfrag, 1155 from, length, transhdrlen, flags); 1156 } 1157 1158 ssize_t ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page, 1159 int offset, size_t size, int flags) 1160 { 1161 struct inet_sock *inet = inet_sk(sk); 1162 struct sk_buff *skb; 1163 struct rtable *rt; 1164 struct ip_options *opt = NULL; 1165 struct inet_cork *cork; 1166 int hh_len; 1167 int mtu; 1168 int len; 1169 int err; 1170 unsigned int maxfraglen, fragheaderlen, fraggap, maxnonfragsize; 1171 1172 if (inet->hdrincl) 1173 return -EPERM; 1174 1175 if (flags&MSG_PROBE) 1176 return 0; 1177 1178 if (skb_queue_empty(&sk->sk_write_queue)) 1179 return -EINVAL; 1180 1181 cork = &inet->cork.base; 1182 rt = (struct rtable *)cork->dst; 1183 if (cork->flags & IPCORK_OPT) 1184 opt = cork->opt; 1185 1186 if (!(rt->dst.dev->features&NETIF_F_SG)) 1187 return -EOPNOTSUPP; 1188 1189 hh_len = LL_RESERVED_SPACE(rt->dst.dev); 1190 mtu = cork->fragsize; 1191 1192 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0); 1193 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen; 1194 maxnonfragsize = ip_sk_ignore_df(sk) ? 0xFFFF : mtu; 1195 1196 if (cork->length + size > maxnonfragsize - fragheaderlen) { 1197 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport, 1198 mtu - (opt ? opt->optlen : 0)); 1199 return -EMSGSIZE; 1200 } 1201 1202 if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL) 1203 return -EINVAL; 1204 1205 cork->length += size; 1206 if ((size + skb->len > mtu) && 1207 (sk->sk_protocol == IPPROTO_UDP) && 1208 (rt->dst.dev->features & NETIF_F_UFO)) { 1209 skb_shinfo(skb)->gso_size = mtu - fragheaderlen; 1210 skb_shinfo(skb)->gso_type = SKB_GSO_UDP; 1211 } 1212 1213 1214 while (size > 0) { 1215 int i; 1216 1217 if (skb_is_gso(skb)) 1218 len = size; 1219 else { 1220 1221 /* Check if the remaining data fits into current packet. */ 1222 len = mtu - skb->len; 1223 if (len < size) 1224 len = maxfraglen - skb->len; 1225 } 1226 if (len <= 0) { 1227 struct sk_buff *skb_prev; 1228 int alloclen; 1229 1230 skb_prev = skb; 1231 fraggap = skb_prev->len - maxfraglen; 1232 1233 alloclen = fragheaderlen + hh_len + fraggap + 15; 1234 skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation); 1235 if (unlikely(!skb)) { 1236 err = -ENOBUFS; 1237 goto error; 1238 } 1239 1240 /* 1241 * Fill in the control structures 1242 */ 1243 skb->ip_summed = CHECKSUM_NONE; 1244 skb->csum = 0; 1245 skb_reserve(skb, hh_len); 1246 1247 /* 1248 * Find where to start putting bytes. 1249 */ 1250 skb_put(skb, fragheaderlen + fraggap); 1251 skb_reset_network_header(skb); 1252 skb->transport_header = (skb->network_header + 1253 fragheaderlen); 1254 if (fraggap) { 1255 skb->csum = skb_copy_and_csum_bits(skb_prev, 1256 maxfraglen, 1257 skb_transport_header(skb), 1258 fraggap, 0); 1259 skb_prev->csum = csum_sub(skb_prev->csum, 1260 skb->csum); 1261 pskb_trim_unique(skb_prev, maxfraglen); 1262 } 1263 1264 /* 1265 * Put the packet on the pending queue. 1266 */ 1267 __skb_queue_tail(&sk->sk_write_queue, skb); 1268 continue; 1269 } 1270 1271 i = skb_shinfo(skb)->nr_frags; 1272 if (len > size) 1273 len = size; 1274 if (skb_can_coalesce(skb, i, page, offset)) { 1275 skb_frag_size_add(&skb_shinfo(skb)->frags[i-1], len); 1276 } else if (i < MAX_SKB_FRAGS) { 1277 get_page(page); 1278 skb_fill_page_desc(skb, i, page, offset, len); 1279 } else { 1280 err = -EMSGSIZE; 1281 goto error; 1282 } 1283 1284 if (skb->ip_summed == CHECKSUM_NONE) { 1285 __wsum csum; 1286 csum = csum_page(page, offset, len); 1287 skb->csum = csum_block_add(skb->csum, csum, skb->len); 1288 } 1289 1290 skb->len += len; 1291 skb->data_len += len; 1292 skb->truesize += len; 1293 atomic_add(len, &sk->sk_wmem_alloc); 1294 offset += len; 1295 size -= len; 1296 } 1297 return 0; 1298 1299 error: 1300 cork->length -= size; 1301 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS); 1302 return err; 1303 } 1304 1305 static void ip_cork_release(struct inet_cork *cork) 1306 { 1307 cork->flags &= ~IPCORK_OPT; 1308 kfree(cork->opt); 1309 cork->opt = NULL; 1310 dst_release(cork->dst); 1311 cork->dst = NULL; 1312 } 1313 1314 /* 1315 * Combined all pending IP fragments on the socket as one IP datagram 1316 * and push them out. 1317 */ 1318 struct sk_buff *__ip_make_skb(struct sock *sk, 1319 struct flowi4 *fl4, 1320 struct sk_buff_head *queue, 1321 struct inet_cork *cork) 1322 { 1323 struct sk_buff *skb, *tmp_skb; 1324 struct sk_buff **tail_skb; 1325 struct inet_sock *inet = inet_sk(sk); 1326 struct net *net = sock_net(sk); 1327 struct ip_options *opt = NULL; 1328 struct rtable *rt = (struct rtable *)cork->dst; 1329 struct iphdr *iph; 1330 __be16 df = 0; 1331 __u8 ttl; 1332 1333 if ((skb = __skb_dequeue(queue)) == NULL) 1334 goto out; 1335 tail_skb = &(skb_shinfo(skb)->frag_list); 1336 1337 /* move skb->data to ip header from ext header */ 1338 if (skb->data < skb_network_header(skb)) 1339 __skb_pull(skb, skb_network_offset(skb)); 1340 while ((tmp_skb = __skb_dequeue(queue)) != NULL) { 1341 __skb_pull(tmp_skb, skb_network_header_len(skb)); 1342 *tail_skb = tmp_skb; 1343 tail_skb = &(tmp_skb->next); 1344 skb->len += tmp_skb->len; 1345 skb->data_len += tmp_skb->len; 1346 skb->truesize += tmp_skb->truesize; 1347 tmp_skb->destructor = NULL; 1348 tmp_skb->sk = NULL; 1349 } 1350 1351 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow 1352 * to fragment the frame generated here. No matter, what transforms 1353 * how transforms change size of the packet, it will come out. 1354 */ 1355 skb->ignore_df = ip_sk_ignore_df(sk); 1356 1357 /* DF bit is set when we want to see DF on outgoing frames. 1358 * If ignore_df is set too, we still allow to fragment this frame 1359 * locally. */ 1360 if (inet->pmtudisc == IP_PMTUDISC_DO || 1361 inet->pmtudisc == IP_PMTUDISC_PROBE || 1362 (skb->len <= dst_mtu(&rt->dst) && 1363 ip_dont_fragment(sk, &rt->dst))) 1364 df = htons(IP_DF); 1365 1366 if (cork->flags & IPCORK_OPT) 1367 opt = cork->opt; 1368 1369 if (cork->ttl != 0) 1370 ttl = cork->ttl; 1371 else if (rt->rt_type == RTN_MULTICAST) 1372 ttl = inet->mc_ttl; 1373 else 1374 ttl = ip_select_ttl(inet, &rt->dst); 1375 1376 iph = ip_hdr(skb); 1377 iph->version = 4; 1378 iph->ihl = 5; 1379 iph->tos = (cork->tos != -1) ? cork->tos : inet->tos; 1380 iph->frag_off = df; 1381 iph->ttl = ttl; 1382 iph->protocol = sk->sk_protocol; 1383 ip_copy_addrs(iph, fl4); 1384 ip_select_ident(skb, sk); 1385 1386 if (opt) { 1387 iph->ihl += opt->optlen>>2; 1388 ip_options_build(skb, opt, cork->addr, rt, 0); 1389 } 1390 1391 skb->priority = (cork->tos != -1) ? cork->priority: sk->sk_priority; 1392 skb->mark = sk->sk_mark; 1393 /* 1394 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec 1395 * on dst refcount 1396 */ 1397 cork->dst = NULL; 1398 skb_dst_set(skb, &rt->dst); 1399 1400 if (iph->protocol == IPPROTO_ICMP) 1401 icmp_out_count(net, ((struct icmphdr *) 1402 skb_transport_header(skb))->type); 1403 1404 ip_cork_release(cork); 1405 out: 1406 return skb; 1407 } 1408 1409 int ip_send_skb(struct net *net, struct sk_buff *skb) 1410 { 1411 int err; 1412 1413 err = ip_local_out(skb); 1414 if (err) { 1415 if (err > 0) 1416 err = net_xmit_errno(err); 1417 if (err) 1418 IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS); 1419 } 1420 1421 return err; 1422 } 1423 1424 int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4) 1425 { 1426 struct sk_buff *skb; 1427 1428 skb = ip_finish_skb(sk, fl4); 1429 if (!skb) 1430 return 0; 1431 1432 /* Netfilter gets whole the not fragmented skb. */ 1433 return ip_send_skb(sock_net(sk), skb); 1434 } 1435 1436 /* 1437 * Throw away all pending data on the socket. 1438 */ 1439 static void __ip_flush_pending_frames(struct sock *sk, 1440 struct sk_buff_head *queue, 1441 struct inet_cork *cork) 1442 { 1443 struct sk_buff *skb; 1444 1445 while ((skb = __skb_dequeue_tail(queue)) != NULL) 1446 kfree_skb(skb); 1447 1448 ip_cork_release(cork); 1449 } 1450 1451 void ip_flush_pending_frames(struct sock *sk) 1452 { 1453 __ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork.base); 1454 } 1455 1456 struct sk_buff *ip_make_skb(struct sock *sk, 1457 struct flowi4 *fl4, 1458 int getfrag(void *from, char *to, int offset, 1459 int len, int odd, struct sk_buff *skb), 1460 void *from, int length, int transhdrlen, 1461 struct ipcm_cookie *ipc, struct rtable **rtp, 1462 unsigned int flags) 1463 { 1464 struct inet_cork cork; 1465 struct sk_buff_head queue; 1466 int err; 1467 1468 if (flags & MSG_PROBE) 1469 return NULL; 1470 1471 __skb_queue_head_init(&queue); 1472 1473 cork.flags = 0; 1474 cork.addr = 0; 1475 cork.opt = NULL; 1476 err = ip_setup_cork(sk, &cork, ipc, rtp); 1477 if (err) 1478 return ERR_PTR(err); 1479 1480 err = __ip_append_data(sk, fl4, &queue, &cork, 1481 ¤t->task_frag, getfrag, 1482 from, length, transhdrlen, flags); 1483 if (err) { 1484 __ip_flush_pending_frames(sk, &queue, &cork); 1485 return ERR_PTR(err); 1486 } 1487 1488 return __ip_make_skb(sk, fl4, &queue, &cork); 1489 } 1490 1491 /* 1492 * Fetch data from kernel space and fill in checksum if needed. 1493 */ 1494 static int ip_reply_glue_bits(void *dptr, char *to, int offset, 1495 int len, int odd, struct sk_buff *skb) 1496 { 1497 __wsum csum; 1498 1499 csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0); 1500 skb->csum = csum_block_add(skb->csum, csum, odd); 1501 return 0; 1502 } 1503 1504 /* 1505 * Generic function to send a packet as reply to another packet. 1506 * Used to send some TCP resets/acks so far. 1507 */ 1508 void ip_send_unicast_reply(struct sock *sk, struct sk_buff *skb, 1509 const struct ip_options *sopt, 1510 __be32 daddr, __be32 saddr, 1511 const struct ip_reply_arg *arg, 1512 unsigned int len) 1513 { 1514 struct ip_options_data replyopts; 1515 struct ipcm_cookie ipc; 1516 struct flowi4 fl4; 1517 struct rtable *rt = skb_rtable(skb); 1518 struct net *net = sock_net(sk); 1519 struct sk_buff *nskb; 1520 int err; 1521 1522 if (__ip_options_echo(&replyopts.opt.opt, skb, sopt)) 1523 return; 1524 1525 ipc.addr = daddr; 1526 ipc.opt = NULL; 1527 ipc.tx_flags = 0; 1528 ipc.ttl = 0; 1529 ipc.tos = -1; 1530 1531 if (replyopts.opt.opt.optlen) { 1532 ipc.opt = &replyopts.opt; 1533 1534 if (replyopts.opt.opt.srr) 1535 daddr = replyopts.opt.opt.faddr; 1536 } 1537 1538 flowi4_init_output(&fl4, arg->bound_dev_if, 1539 IP4_REPLY_MARK(net, skb->mark), 1540 RT_TOS(arg->tos), 1541 RT_SCOPE_UNIVERSE, ip_hdr(skb)->protocol, 1542 ip_reply_arg_flowi_flags(arg), 1543 daddr, saddr, 1544 tcp_hdr(skb)->source, tcp_hdr(skb)->dest); 1545 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4)); 1546 rt = ip_route_output_key(net, &fl4); 1547 if (IS_ERR(rt)) 1548 return; 1549 1550 inet_sk(sk)->tos = arg->tos; 1551 1552 sk->sk_priority = skb->priority; 1553 sk->sk_protocol = ip_hdr(skb)->protocol; 1554 sk->sk_bound_dev_if = arg->bound_dev_if; 1555 sk->sk_sndbuf = sysctl_wmem_default; 1556 err = ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base, 1557 len, 0, &ipc, &rt, MSG_DONTWAIT); 1558 if (unlikely(err)) { 1559 ip_flush_pending_frames(sk); 1560 goto out; 1561 } 1562 1563 nskb = skb_peek(&sk->sk_write_queue); 1564 if (nskb) { 1565 if (arg->csumoffset >= 0) 1566 *((__sum16 *)skb_transport_header(nskb) + 1567 arg->csumoffset) = csum_fold(csum_add(nskb->csum, 1568 arg->csum)); 1569 nskb->ip_summed = CHECKSUM_NONE; 1570 skb_set_queue_mapping(nskb, skb_get_queue_mapping(skb)); 1571 ip_push_pending_frames(sk, &fl4); 1572 } 1573 out: 1574 ip_rt_put(rt); 1575 } 1576 1577 void __init ip_init(void) 1578 { 1579 ip_rt_init(); 1580 inet_initpeers(); 1581 1582 #if defined(CONFIG_IP_MULTICAST) 1583 igmp_mc_init(); 1584 #endif 1585 } 1586