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_sk(struct sock *sk, 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, sk, skb, NULL, 101 skb_dst(skb)->dev, dst_output_sk); 102 } 103 104 int __ip_local_out(struct sk_buff *skb) 105 { 106 return __ip_local_out_sk(skb->sk, skb); 107 } 108 109 int ip_local_out_sk(struct sock *sk, struct sk_buff *skb) 110 { 111 int err; 112 113 err = __ip_local_out(skb); 114 if (likely(err == 1)) 115 err = dst_output_sk(sk, skb); 116 117 return err; 118 } 119 EXPORT_SYMBOL_GPL(ip_local_out_sk); 120 121 static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst) 122 { 123 int ttl = inet->uc_ttl; 124 125 if (ttl < 0) 126 ttl = ip4_dst_hoplimit(dst); 127 return ttl; 128 } 129 130 /* 131 * Add an ip header to a skbuff and send it out. 132 * 133 */ 134 int ip_build_and_send_pkt(struct sk_buff *skb, struct sock *sk, 135 __be32 saddr, __be32 daddr, struct ip_options_rcu *opt) 136 { 137 struct inet_sock *inet = inet_sk(sk); 138 struct rtable *rt = skb_rtable(skb); 139 struct iphdr *iph; 140 141 /* Build the IP header. */ 142 skb_push(skb, sizeof(struct iphdr) + (opt ? opt->opt.optlen : 0)); 143 skb_reset_network_header(skb); 144 iph = ip_hdr(skb); 145 iph->version = 4; 146 iph->ihl = 5; 147 iph->tos = inet->tos; 148 if (ip_dont_fragment(sk, &rt->dst)) 149 iph->frag_off = htons(IP_DF); 150 else 151 iph->frag_off = 0; 152 iph->ttl = ip_select_ttl(inet, &rt->dst); 153 iph->daddr = (opt && opt->opt.srr ? opt->opt.faddr : daddr); 154 iph->saddr = saddr; 155 iph->protocol = sk->sk_protocol; 156 ip_select_ident(sock_net(sk), skb, sk); 157 158 if (opt && opt->opt.optlen) { 159 iph->ihl += opt->opt.optlen>>2; 160 ip_options_build(skb, &opt->opt, daddr, rt, 0); 161 } 162 163 skb->priority = sk->sk_priority; 164 skb->mark = sk->sk_mark; 165 166 /* Send it out. */ 167 return ip_local_out(skb); 168 } 169 EXPORT_SYMBOL_GPL(ip_build_and_send_pkt); 170 171 static inline int ip_finish_output2(struct sock *sk, struct sk_buff *skb) 172 { 173 struct dst_entry *dst = skb_dst(skb); 174 struct rtable *rt = (struct rtable *)dst; 175 struct net_device *dev = dst->dev; 176 unsigned int hh_len = LL_RESERVED_SPACE(dev); 177 struct neighbour *neigh; 178 u32 nexthop; 179 180 if (rt->rt_type == RTN_MULTICAST) { 181 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUTMCAST, skb->len); 182 } else if (rt->rt_type == RTN_BROADCAST) 183 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUTBCAST, skb->len); 184 185 /* Be paranoid, rather than too clever. */ 186 if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) { 187 struct sk_buff *skb2; 188 189 skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev)); 190 if (!skb2) { 191 kfree_skb(skb); 192 return -ENOMEM; 193 } 194 if (skb->sk) 195 skb_set_owner_w(skb2, skb->sk); 196 consume_skb(skb); 197 skb = skb2; 198 } 199 200 rcu_read_lock_bh(); 201 nexthop = (__force u32) rt_nexthop(rt, ip_hdr(skb)->daddr); 202 neigh = __ipv4_neigh_lookup_noref(dev, nexthop); 203 if (unlikely(!neigh)) 204 neigh = __neigh_create(&arp_tbl, &nexthop, dev, false); 205 if (!IS_ERR(neigh)) { 206 int res = dst_neigh_output(dst, neigh, skb); 207 208 rcu_read_unlock_bh(); 209 return res; 210 } 211 rcu_read_unlock_bh(); 212 213 net_dbg_ratelimited("%s: No header cache and no neighbour!\n", 214 __func__); 215 kfree_skb(skb); 216 return -EINVAL; 217 } 218 219 static int ip_finish_output_gso(struct sock *sk, struct sk_buff *skb) 220 { 221 netdev_features_t features; 222 struct sk_buff *segs; 223 int ret = 0; 224 225 /* common case: locally created skb or seglen is <= mtu */ 226 if (((IPCB(skb)->flags & IPSKB_FORWARDED) == 0) || 227 skb_gso_network_seglen(skb) <= ip_skb_dst_mtu(skb)) 228 return ip_finish_output2(sk, skb); 229 230 /* Slowpath - GSO segment length is exceeding the dst MTU. 231 * 232 * This can happen in two cases: 233 * 1) TCP GRO packet, DF bit not set 234 * 2) skb arrived via virtio-net, we thus get TSO/GSO skbs directly 235 * from host network stack. 236 */ 237 features = netif_skb_features(skb); 238 segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK); 239 if (IS_ERR_OR_NULL(segs)) { 240 kfree_skb(skb); 241 return -ENOMEM; 242 } 243 244 consume_skb(skb); 245 246 do { 247 struct sk_buff *nskb = segs->next; 248 int err; 249 250 segs->next = NULL; 251 err = ip_fragment(sk, segs, ip_finish_output2); 252 253 if (err && ret == 0) 254 ret = err; 255 segs = nskb; 256 } while (segs); 257 258 return ret; 259 } 260 261 static int ip_finish_output(struct sock *sk, struct sk_buff *skb) 262 { 263 #if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM) 264 /* Policy lookup after SNAT yielded a new policy */ 265 if (skb_dst(skb)->xfrm) { 266 IPCB(skb)->flags |= IPSKB_REROUTED; 267 return dst_output_sk(sk, skb); 268 } 269 #endif 270 if (skb_is_gso(skb)) 271 return ip_finish_output_gso(sk, skb); 272 273 if (skb->len > ip_skb_dst_mtu(skb)) 274 return ip_fragment(sk, skb, ip_finish_output2); 275 276 return ip_finish_output2(sk, skb); 277 } 278 279 int ip_mc_output(struct sock *sk, struct sk_buff *skb) 280 { 281 struct rtable *rt = skb_rtable(skb); 282 struct net_device *dev = rt->dst.dev; 283 284 /* 285 * If the indicated interface is up and running, send the packet. 286 */ 287 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len); 288 289 skb->dev = dev; 290 skb->protocol = htons(ETH_P_IP); 291 292 /* 293 * Multicasts are looped back for other local users 294 */ 295 296 if (rt->rt_flags&RTCF_MULTICAST) { 297 if (sk_mc_loop(sk) 298 #ifdef CONFIG_IP_MROUTE 299 /* Small optimization: do not loopback not local frames, 300 which returned after forwarding; they will be dropped 301 by ip_mr_input in any case. 302 Note, that local frames are looped back to be delivered 303 to local recipients. 304 305 This check is duplicated in ip_mr_input at the moment. 306 */ 307 && 308 ((rt->rt_flags & RTCF_LOCAL) || 309 !(IPCB(skb)->flags & IPSKB_FORWARDED)) 310 #endif 311 ) { 312 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC); 313 if (newskb) 314 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, 315 sk, newskb, NULL, newskb->dev, 316 dev_loopback_xmit); 317 } 318 319 /* Multicasts with ttl 0 must not go beyond the host */ 320 321 if (ip_hdr(skb)->ttl == 0) { 322 kfree_skb(skb); 323 return 0; 324 } 325 } 326 327 if (rt->rt_flags&RTCF_BROADCAST) { 328 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC); 329 if (newskb) 330 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, sk, newskb, 331 NULL, newskb->dev, dev_loopback_xmit); 332 } 333 334 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, sk, skb, NULL, 335 skb->dev, ip_finish_output, 336 !(IPCB(skb)->flags & IPSKB_REROUTED)); 337 } 338 339 int ip_output(struct sock *sk, struct sk_buff *skb) 340 { 341 struct net_device *dev = skb_dst(skb)->dev; 342 343 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len); 344 345 skb->dev = dev; 346 skb->protocol = htons(ETH_P_IP); 347 348 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, sk, skb, 349 NULL, dev, 350 ip_finish_output, 351 !(IPCB(skb)->flags & IPSKB_REROUTED)); 352 } 353 354 /* 355 * copy saddr and daddr, possibly using 64bit load/stores 356 * Equivalent to : 357 * iph->saddr = fl4->saddr; 358 * iph->daddr = fl4->daddr; 359 */ 360 static void ip_copy_addrs(struct iphdr *iph, const struct flowi4 *fl4) 361 { 362 BUILD_BUG_ON(offsetof(typeof(*fl4), daddr) != 363 offsetof(typeof(*fl4), saddr) + sizeof(fl4->saddr)); 364 memcpy(&iph->saddr, &fl4->saddr, 365 sizeof(fl4->saddr) + sizeof(fl4->daddr)); 366 } 367 368 /* Note: skb->sk can be different from sk, in case of tunnels */ 369 int ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl) 370 { 371 struct inet_sock *inet = inet_sk(sk); 372 struct ip_options_rcu *inet_opt; 373 struct flowi4 *fl4; 374 struct rtable *rt; 375 struct iphdr *iph; 376 int res; 377 378 /* Skip all of this if the packet is already routed, 379 * f.e. by something like SCTP. 380 */ 381 rcu_read_lock(); 382 inet_opt = rcu_dereference(inet->inet_opt); 383 fl4 = &fl->u.ip4; 384 rt = skb_rtable(skb); 385 if (rt) 386 goto packet_routed; 387 388 /* Make sure we can route this packet. */ 389 rt = (struct rtable *)__sk_dst_check(sk, 0); 390 if (!rt) { 391 __be32 daddr; 392 393 /* Use correct destination address if we have options. */ 394 daddr = inet->inet_daddr; 395 if (inet_opt && inet_opt->opt.srr) 396 daddr = inet_opt->opt.faddr; 397 398 /* If this fails, retransmit mechanism of transport layer will 399 * keep trying until route appears or the connection times 400 * itself out. 401 */ 402 rt = ip_route_output_ports(sock_net(sk), fl4, sk, 403 daddr, inet->inet_saddr, 404 inet->inet_dport, 405 inet->inet_sport, 406 sk->sk_protocol, 407 RT_CONN_FLAGS(sk), 408 sk->sk_bound_dev_if); 409 if (IS_ERR(rt)) 410 goto no_route; 411 sk_setup_caps(sk, &rt->dst); 412 } 413 skb_dst_set_noref(skb, &rt->dst); 414 415 packet_routed: 416 if (inet_opt && inet_opt->opt.is_strictroute && rt->rt_uses_gateway) 417 goto no_route; 418 419 /* OK, we know where to send it, allocate and build IP header. */ 420 skb_push(skb, sizeof(struct iphdr) + (inet_opt ? inet_opt->opt.optlen : 0)); 421 skb_reset_network_header(skb); 422 iph = ip_hdr(skb); 423 *((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (inet->tos & 0xff)); 424 if (ip_dont_fragment(sk, &rt->dst) && !skb->ignore_df) 425 iph->frag_off = htons(IP_DF); 426 else 427 iph->frag_off = 0; 428 iph->ttl = ip_select_ttl(inet, &rt->dst); 429 iph->protocol = sk->sk_protocol; 430 ip_copy_addrs(iph, fl4); 431 432 /* Transport layer set skb->h.foo itself. */ 433 434 if (inet_opt && inet_opt->opt.optlen) { 435 iph->ihl += inet_opt->opt.optlen >> 2; 436 ip_options_build(skb, &inet_opt->opt, inet->inet_daddr, rt, 0); 437 } 438 439 ip_select_ident_segs(sock_net(sk), skb, sk, 440 skb_shinfo(skb)->gso_segs ?: 1); 441 442 /* TODO : should we use skb->sk here instead of sk ? */ 443 skb->priority = sk->sk_priority; 444 skb->mark = sk->sk_mark; 445 446 res = ip_local_out(skb); 447 rcu_read_unlock(); 448 return res; 449 450 no_route: 451 rcu_read_unlock(); 452 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES); 453 kfree_skb(skb); 454 return -EHOSTUNREACH; 455 } 456 EXPORT_SYMBOL(ip_queue_xmit); 457 458 static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from) 459 { 460 to->pkt_type = from->pkt_type; 461 to->priority = from->priority; 462 to->protocol = from->protocol; 463 skb_dst_drop(to); 464 skb_dst_copy(to, from); 465 to->dev = from->dev; 466 to->mark = from->mark; 467 468 /* Copy the flags to each fragment. */ 469 IPCB(to)->flags = IPCB(from)->flags; 470 471 #ifdef CONFIG_NET_SCHED 472 to->tc_index = from->tc_index; 473 #endif 474 nf_copy(to, from); 475 #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE) 476 to->ipvs_property = from->ipvs_property; 477 #endif 478 skb_copy_secmark(to, from); 479 } 480 481 /* 482 * This IP datagram is too large to be sent in one piece. Break it up into 483 * smaller pieces (each of size equal to IP header plus 484 * a block of the data of the original IP data part) that will yet fit in a 485 * single device frame, and queue such a frame for sending. 486 */ 487 488 int ip_fragment(struct sock *sk, struct sk_buff *skb, 489 int (*output)(struct sock *, struct sk_buff *)) 490 { 491 struct iphdr *iph; 492 int ptr; 493 struct net_device *dev; 494 struct sk_buff *skb2; 495 unsigned int mtu, hlen, left, len, ll_rs; 496 int offset; 497 __be16 not_last_frag; 498 struct rtable *rt = skb_rtable(skb); 499 int err = 0; 500 501 dev = rt->dst.dev; 502 503 /* 504 * Point into the IP datagram header. 505 */ 506 507 iph = ip_hdr(skb); 508 509 mtu = ip_skb_dst_mtu(skb); 510 if (unlikely(((iph->frag_off & htons(IP_DF)) && !skb->ignore_df) || 511 (IPCB(skb)->frag_max_size && 512 IPCB(skb)->frag_max_size > mtu))) { 513 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); 514 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, 515 htonl(mtu)); 516 kfree_skb(skb); 517 return -EMSGSIZE; 518 } 519 520 /* 521 * Setup starting values. 522 */ 523 524 hlen = iph->ihl * 4; 525 mtu = mtu - hlen; /* Size of data space */ 526 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) 527 if (skb->nf_bridge) 528 mtu -= nf_bridge_mtu_reduction(skb); 529 #endif 530 IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE; 531 532 /* When frag_list is given, use it. First, check its validity: 533 * some transformers could create wrong frag_list or break existing 534 * one, it is not prohibited. In this case fall back to copying. 535 * 536 * LATER: this step can be merged to real generation of fragments, 537 * we can switch to copy when see the first bad fragment. 538 */ 539 if (skb_has_frag_list(skb)) { 540 struct sk_buff *frag, *frag2; 541 int first_len = skb_pagelen(skb); 542 543 if (first_len - hlen > mtu || 544 ((first_len - hlen) & 7) || 545 ip_is_fragment(iph) || 546 skb_cloned(skb)) 547 goto slow_path; 548 549 skb_walk_frags(skb, frag) { 550 /* Correct geometry. */ 551 if (frag->len > mtu || 552 ((frag->len & 7) && frag->next) || 553 skb_headroom(frag) < hlen) 554 goto slow_path_clean; 555 556 /* Partially cloned skb? */ 557 if (skb_shared(frag)) 558 goto slow_path_clean; 559 560 BUG_ON(frag->sk); 561 if (skb->sk) { 562 frag->sk = skb->sk; 563 frag->destructor = sock_wfree; 564 } 565 skb->truesize -= frag->truesize; 566 } 567 568 /* Everything is OK. Generate! */ 569 570 err = 0; 571 offset = 0; 572 frag = skb_shinfo(skb)->frag_list; 573 skb_frag_list_init(skb); 574 skb->data_len = first_len - skb_headlen(skb); 575 skb->len = first_len; 576 iph->tot_len = htons(first_len); 577 iph->frag_off = htons(IP_MF); 578 ip_send_check(iph); 579 580 for (;;) { 581 /* Prepare header of the next frame, 582 * before previous one went down. */ 583 if (frag) { 584 frag->ip_summed = CHECKSUM_NONE; 585 skb_reset_transport_header(frag); 586 __skb_push(frag, hlen); 587 skb_reset_network_header(frag); 588 memcpy(skb_network_header(frag), iph, hlen); 589 iph = ip_hdr(frag); 590 iph->tot_len = htons(frag->len); 591 ip_copy_metadata(frag, skb); 592 if (offset == 0) 593 ip_options_fragment(frag); 594 offset += skb->len - hlen; 595 iph->frag_off = htons(offset>>3); 596 if (frag->next) 597 iph->frag_off |= htons(IP_MF); 598 /* Ready, complete checksum */ 599 ip_send_check(iph); 600 } 601 602 err = output(sk, skb); 603 604 if (!err) 605 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES); 606 if (err || !frag) 607 break; 608 609 skb = frag; 610 frag = skb->next; 611 skb->next = NULL; 612 } 613 614 if (err == 0) { 615 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS); 616 return 0; 617 } 618 619 while (frag) { 620 skb = frag->next; 621 kfree_skb(frag); 622 frag = skb; 623 } 624 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); 625 return err; 626 627 slow_path_clean: 628 skb_walk_frags(skb, frag2) { 629 if (frag2 == frag) 630 break; 631 frag2->sk = NULL; 632 frag2->destructor = NULL; 633 skb->truesize += frag2->truesize; 634 } 635 } 636 637 slow_path: 638 /* for offloaded checksums cleanup checksum before fragmentation */ 639 if ((skb->ip_summed == CHECKSUM_PARTIAL) && skb_checksum_help(skb)) 640 goto fail; 641 iph = ip_hdr(skb); 642 643 left = skb->len - hlen; /* Space per frame */ 644 ptr = hlen; /* Where to start from */ 645 646 ll_rs = LL_RESERVED_SPACE(rt->dst.dev); 647 648 /* 649 * Fragment the datagram. 650 */ 651 652 offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3; 653 not_last_frag = iph->frag_off & htons(IP_MF); 654 655 /* 656 * Keep copying data until we run out. 657 */ 658 659 while (left > 0) { 660 len = left; 661 /* IF: it doesn't fit, use 'mtu' - the data space left */ 662 if (len > mtu) 663 len = mtu; 664 /* IF: we are not sending up to and including the packet end 665 then align the next start on an eight byte boundary */ 666 if (len < left) { 667 len &= ~7; 668 } 669 670 /* Allocate buffer */ 671 skb2 = alloc_skb(len + hlen + ll_rs, GFP_ATOMIC); 672 if (!skb2) { 673 err = -ENOMEM; 674 goto fail; 675 } 676 677 /* 678 * Set up data on packet 679 */ 680 681 ip_copy_metadata(skb2, skb); 682 skb_reserve(skb2, ll_rs); 683 skb_put(skb2, len + hlen); 684 skb_reset_network_header(skb2); 685 skb2->transport_header = skb2->network_header + hlen; 686 687 /* 688 * Charge the memory for the fragment to any owner 689 * it might possess 690 */ 691 692 if (skb->sk) 693 skb_set_owner_w(skb2, skb->sk); 694 695 /* 696 * Copy the packet header into the new buffer. 697 */ 698 699 skb_copy_from_linear_data(skb, skb_network_header(skb2), hlen); 700 701 /* 702 * Copy a block of the IP datagram. 703 */ 704 if (skb_copy_bits(skb, ptr, skb_transport_header(skb2), len)) 705 BUG(); 706 left -= len; 707 708 /* 709 * Fill in the new header fields. 710 */ 711 iph = ip_hdr(skb2); 712 iph->frag_off = htons((offset >> 3)); 713 714 /* ANK: dirty, but effective trick. Upgrade options only if 715 * the segment to be fragmented was THE FIRST (otherwise, 716 * options are already fixed) and make it ONCE 717 * on the initial skb, so that all the following fragments 718 * will inherit fixed options. 719 */ 720 if (offset == 0) 721 ip_options_fragment(skb); 722 723 /* 724 * Added AC : If we are fragmenting a fragment that's not the 725 * last fragment then keep MF on each bit 726 */ 727 if (left > 0 || not_last_frag) 728 iph->frag_off |= htons(IP_MF); 729 ptr += len; 730 offset += len; 731 732 /* 733 * Put this fragment into the sending queue. 734 */ 735 iph->tot_len = htons(len + hlen); 736 737 ip_send_check(iph); 738 739 err = output(sk, skb2); 740 if (err) 741 goto fail; 742 743 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES); 744 } 745 consume_skb(skb); 746 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS); 747 return err; 748 749 fail: 750 kfree_skb(skb); 751 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); 752 return err; 753 } 754 EXPORT_SYMBOL(ip_fragment); 755 756 int 757 ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb) 758 { 759 struct msghdr *msg = from; 760 761 if (skb->ip_summed == CHECKSUM_PARTIAL) { 762 if (copy_from_iter(to, len, &msg->msg_iter) != len) 763 return -EFAULT; 764 } else { 765 __wsum csum = 0; 766 if (csum_and_copy_from_iter(to, len, &csum, &msg->msg_iter) != len) 767 return -EFAULT; 768 skb->csum = csum_block_add(skb->csum, csum, odd); 769 } 770 return 0; 771 } 772 EXPORT_SYMBOL(ip_generic_getfrag); 773 774 static inline __wsum 775 csum_page(struct page *page, int offset, int copy) 776 { 777 char *kaddr; 778 __wsum csum; 779 kaddr = kmap(page); 780 csum = csum_partial(kaddr + offset, copy, 0); 781 kunmap(page); 782 return csum; 783 } 784 785 static inline int ip_ufo_append_data(struct sock *sk, 786 struct sk_buff_head *queue, 787 int getfrag(void *from, char *to, int offset, int len, 788 int odd, struct sk_buff *skb), 789 void *from, int length, int hh_len, int fragheaderlen, 790 int transhdrlen, int maxfraglen, unsigned int flags) 791 { 792 struct sk_buff *skb; 793 int err; 794 795 /* There is support for UDP fragmentation offload by network 796 * device, so create one single skb packet containing complete 797 * udp datagram 798 */ 799 skb = skb_peek_tail(queue); 800 if (!skb) { 801 skb = sock_alloc_send_skb(sk, 802 hh_len + fragheaderlen + transhdrlen + 20, 803 (flags & MSG_DONTWAIT), &err); 804 805 if (!skb) 806 return err; 807 808 /* reserve space for Hardware header */ 809 skb_reserve(skb, hh_len); 810 811 /* create space for UDP/IP header */ 812 skb_put(skb, fragheaderlen + transhdrlen); 813 814 /* initialize network header pointer */ 815 skb_reset_network_header(skb); 816 817 /* initialize protocol header pointer */ 818 skb->transport_header = skb->network_header + fragheaderlen; 819 820 skb->csum = 0; 821 822 __skb_queue_tail(queue, skb); 823 } else if (skb_is_gso(skb)) { 824 goto append; 825 } 826 827 skb->ip_summed = CHECKSUM_PARTIAL; 828 /* specify the length of each IP datagram fragment */ 829 skb_shinfo(skb)->gso_size = maxfraglen - fragheaderlen; 830 skb_shinfo(skb)->gso_type = SKB_GSO_UDP; 831 832 append: 833 return skb_append_datato_frags(sk, skb, getfrag, from, 834 (length - transhdrlen)); 835 } 836 837 static int __ip_append_data(struct sock *sk, 838 struct flowi4 *fl4, 839 struct sk_buff_head *queue, 840 struct inet_cork *cork, 841 struct page_frag *pfrag, 842 int getfrag(void *from, char *to, int offset, 843 int len, int odd, struct sk_buff *skb), 844 void *from, int length, int transhdrlen, 845 unsigned int flags) 846 { 847 struct inet_sock *inet = inet_sk(sk); 848 struct sk_buff *skb; 849 850 struct ip_options *opt = cork->opt; 851 int hh_len; 852 int exthdrlen; 853 int mtu; 854 int copy; 855 int err; 856 int offset = 0; 857 unsigned int maxfraglen, fragheaderlen, maxnonfragsize; 858 int csummode = CHECKSUM_NONE; 859 struct rtable *rt = (struct rtable *)cork->dst; 860 u32 tskey = 0; 861 862 skb = skb_peek_tail(queue); 863 864 exthdrlen = !skb ? rt->dst.header_len : 0; 865 mtu = cork->fragsize; 866 if (cork->tx_flags & SKBTX_ANY_SW_TSTAMP && 867 sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID) 868 tskey = sk->sk_tskey++; 869 870 hh_len = LL_RESERVED_SPACE(rt->dst.dev); 871 872 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0); 873 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen; 874 maxnonfragsize = ip_sk_ignore_df(sk) ? 0xFFFF : mtu; 875 876 if (cork->length + length > maxnonfragsize - fragheaderlen) { 877 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport, 878 mtu - (opt ? opt->optlen : 0)); 879 return -EMSGSIZE; 880 } 881 882 /* 883 * transhdrlen > 0 means that this is the first fragment and we wish 884 * it won't be fragmented in the future. 885 */ 886 if (transhdrlen && 887 length + fragheaderlen <= mtu && 888 rt->dst.dev->features & NETIF_F_V4_CSUM && 889 !exthdrlen) 890 csummode = CHECKSUM_PARTIAL; 891 892 cork->length += length; 893 if (((length > mtu) || (skb && skb_is_gso(skb))) && 894 (sk->sk_protocol == IPPROTO_UDP) && 895 (rt->dst.dev->features & NETIF_F_UFO) && !rt->dst.header_len && 896 (sk->sk_type == SOCK_DGRAM)) { 897 err = ip_ufo_append_data(sk, queue, getfrag, from, length, 898 hh_len, fragheaderlen, transhdrlen, 899 maxfraglen, flags); 900 if (err) 901 goto error; 902 return 0; 903 } 904 905 /* So, what's going on in the loop below? 906 * 907 * We use calculated fragment length to generate chained skb, 908 * each of segments is IP fragment ready for sending to network after 909 * adding appropriate IP header. 910 */ 911 912 if (!skb) 913 goto alloc_new_skb; 914 915 while (length > 0) { 916 /* Check if the remaining data fits into current packet. */ 917 copy = mtu - skb->len; 918 if (copy < length) 919 copy = maxfraglen - skb->len; 920 if (copy <= 0) { 921 char *data; 922 unsigned int datalen; 923 unsigned int fraglen; 924 unsigned int fraggap; 925 unsigned int alloclen; 926 struct sk_buff *skb_prev; 927 alloc_new_skb: 928 skb_prev = skb; 929 if (skb_prev) 930 fraggap = skb_prev->len - maxfraglen; 931 else 932 fraggap = 0; 933 934 /* 935 * If remaining data exceeds the mtu, 936 * we know we need more fragment(s). 937 */ 938 datalen = length + fraggap; 939 if (datalen > mtu - fragheaderlen) 940 datalen = maxfraglen - fragheaderlen; 941 fraglen = datalen + fragheaderlen; 942 943 if ((flags & MSG_MORE) && 944 !(rt->dst.dev->features&NETIF_F_SG)) 945 alloclen = mtu; 946 else 947 alloclen = fraglen; 948 949 alloclen += exthdrlen; 950 951 /* The last fragment gets additional space at tail. 952 * Note, with MSG_MORE we overallocate on fragments, 953 * because we have no idea what fragment will be 954 * the last. 955 */ 956 if (datalen == length + fraggap) 957 alloclen += rt->dst.trailer_len; 958 959 if (transhdrlen) { 960 skb = sock_alloc_send_skb(sk, 961 alloclen + hh_len + 15, 962 (flags & MSG_DONTWAIT), &err); 963 } else { 964 skb = NULL; 965 if (atomic_read(&sk->sk_wmem_alloc) <= 966 2 * sk->sk_sndbuf) 967 skb = sock_wmalloc(sk, 968 alloclen + hh_len + 15, 1, 969 sk->sk_allocation); 970 if (unlikely(!skb)) 971 err = -ENOBUFS; 972 } 973 if (!skb) 974 goto error; 975 976 /* 977 * Fill in the control structures 978 */ 979 skb->ip_summed = csummode; 980 skb->csum = 0; 981 skb_reserve(skb, hh_len); 982 983 /* only the initial fragment is time stamped */ 984 skb_shinfo(skb)->tx_flags = cork->tx_flags; 985 cork->tx_flags = 0; 986 skb_shinfo(skb)->tskey = tskey; 987 tskey = 0; 988 989 /* 990 * Find where to start putting bytes. 991 */ 992 data = skb_put(skb, fraglen + exthdrlen); 993 skb_set_network_header(skb, exthdrlen); 994 skb->transport_header = (skb->network_header + 995 fragheaderlen); 996 data += fragheaderlen + exthdrlen; 997 998 if (fraggap) { 999 skb->csum = skb_copy_and_csum_bits( 1000 skb_prev, maxfraglen, 1001 data + transhdrlen, fraggap, 0); 1002 skb_prev->csum = csum_sub(skb_prev->csum, 1003 skb->csum); 1004 data += fraggap; 1005 pskb_trim_unique(skb_prev, maxfraglen); 1006 } 1007 1008 copy = datalen - transhdrlen - fraggap; 1009 if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) { 1010 err = -EFAULT; 1011 kfree_skb(skb); 1012 goto error; 1013 } 1014 1015 offset += copy; 1016 length -= datalen - fraggap; 1017 transhdrlen = 0; 1018 exthdrlen = 0; 1019 csummode = CHECKSUM_NONE; 1020 1021 /* 1022 * Put the packet on the pending queue. 1023 */ 1024 __skb_queue_tail(queue, skb); 1025 continue; 1026 } 1027 1028 if (copy > length) 1029 copy = length; 1030 1031 if (!(rt->dst.dev->features&NETIF_F_SG)) { 1032 unsigned int off; 1033 1034 off = skb->len; 1035 if (getfrag(from, skb_put(skb, copy), 1036 offset, copy, off, skb) < 0) { 1037 __skb_trim(skb, off); 1038 err = -EFAULT; 1039 goto error; 1040 } 1041 } else { 1042 int i = skb_shinfo(skb)->nr_frags; 1043 1044 err = -ENOMEM; 1045 if (!sk_page_frag_refill(sk, pfrag)) 1046 goto error; 1047 1048 if (!skb_can_coalesce(skb, i, pfrag->page, 1049 pfrag->offset)) { 1050 err = -EMSGSIZE; 1051 if (i == MAX_SKB_FRAGS) 1052 goto error; 1053 1054 __skb_fill_page_desc(skb, i, pfrag->page, 1055 pfrag->offset, 0); 1056 skb_shinfo(skb)->nr_frags = ++i; 1057 get_page(pfrag->page); 1058 } 1059 copy = min_t(int, copy, pfrag->size - pfrag->offset); 1060 if (getfrag(from, 1061 page_address(pfrag->page) + pfrag->offset, 1062 offset, copy, skb->len, skb) < 0) 1063 goto error_efault; 1064 1065 pfrag->offset += copy; 1066 skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy); 1067 skb->len += copy; 1068 skb->data_len += copy; 1069 skb->truesize += copy; 1070 atomic_add(copy, &sk->sk_wmem_alloc); 1071 } 1072 offset += copy; 1073 length -= copy; 1074 } 1075 1076 return 0; 1077 1078 error_efault: 1079 err = -EFAULT; 1080 error: 1081 cork->length -= length; 1082 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS); 1083 return err; 1084 } 1085 1086 static int ip_setup_cork(struct sock *sk, struct inet_cork *cork, 1087 struct ipcm_cookie *ipc, struct rtable **rtp) 1088 { 1089 struct ip_options_rcu *opt; 1090 struct rtable *rt; 1091 1092 /* 1093 * setup for corking. 1094 */ 1095 opt = ipc->opt; 1096 if (opt) { 1097 if (!cork->opt) { 1098 cork->opt = kmalloc(sizeof(struct ip_options) + 40, 1099 sk->sk_allocation); 1100 if (unlikely(!cork->opt)) 1101 return -ENOBUFS; 1102 } 1103 memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen); 1104 cork->flags |= IPCORK_OPT; 1105 cork->addr = ipc->addr; 1106 } 1107 rt = *rtp; 1108 if (unlikely(!rt)) 1109 return -EFAULT; 1110 /* 1111 * We steal reference to this route, caller should not release it 1112 */ 1113 *rtp = NULL; 1114 cork->fragsize = ip_sk_use_pmtu(sk) ? 1115 dst_mtu(&rt->dst) : rt->dst.dev->mtu; 1116 cork->dst = &rt->dst; 1117 cork->length = 0; 1118 cork->ttl = ipc->ttl; 1119 cork->tos = ipc->tos; 1120 cork->priority = ipc->priority; 1121 cork->tx_flags = ipc->tx_flags; 1122 1123 return 0; 1124 } 1125 1126 /* 1127 * ip_append_data() and ip_append_page() can make one large IP datagram 1128 * from many pieces of data. Each pieces will be holded on the socket 1129 * until ip_push_pending_frames() is called. Each piece can be a page 1130 * or non-page data. 1131 * 1132 * Not only UDP, other transport protocols - e.g. raw sockets - can use 1133 * this interface potentially. 1134 * 1135 * LATER: length must be adjusted by pad at tail, when it is required. 1136 */ 1137 int ip_append_data(struct sock *sk, struct flowi4 *fl4, 1138 int getfrag(void *from, char *to, int offset, int len, 1139 int odd, struct sk_buff *skb), 1140 void *from, int length, int transhdrlen, 1141 struct ipcm_cookie *ipc, struct rtable **rtp, 1142 unsigned int flags) 1143 { 1144 struct inet_sock *inet = inet_sk(sk); 1145 int err; 1146 1147 if (flags&MSG_PROBE) 1148 return 0; 1149 1150 if (skb_queue_empty(&sk->sk_write_queue)) { 1151 err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp); 1152 if (err) 1153 return err; 1154 } else { 1155 transhdrlen = 0; 1156 } 1157 1158 return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base, 1159 sk_page_frag(sk), getfrag, 1160 from, length, transhdrlen, flags); 1161 } 1162 1163 ssize_t ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page, 1164 int offset, size_t size, int flags) 1165 { 1166 struct inet_sock *inet = inet_sk(sk); 1167 struct sk_buff *skb; 1168 struct rtable *rt; 1169 struct ip_options *opt = NULL; 1170 struct inet_cork *cork; 1171 int hh_len; 1172 int mtu; 1173 int len; 1174 int err; 1175 unsigned int maxfraglen, fragheaderlen, fraggap, maxnonfragsize; 1176 1177 if (inet->hdrincl) 1178 return -EPERM; 1179 1180 if (flags&MSG_PROBE) 1181 return 0; 1182 1183 if (skb_queue_empty(&sk->sk_write_queue)) 1184 return -EINVAL; 1185 1186 cork = &inet->cork.base; 1187 rt = (struct rtable *)cork->dst; 1188 if (cork->flags & IPCORK_OPT) 1189 opt = cork->opt; 1190 1191 if (!(rt->dst.dev->features&NETIF_F_SG)) 1192 return -EOPNOTSUPP; 1193 1194 hh_len = LL_RESERVED_SPACE(rt->dst.dev); 1195 mtu = cork->fragsize; 1196 1197 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0); 1198 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen; 1199 maxnonfragsize = ip_sk_ignore_df(sk) ? 0xFFFF : mtu; 1200 1201 if (cork->length + size > maxnonfragsize - fragheaderlen) { 1202 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport, 1203 mtu - (opt ? opt->optlen : 0)); 1204 return -EMSGSIZE; 1205 } 1206 1207 skb = skb_peek_tail(&sk->sk_write_queue); 1208 if (!skb) 1209 return -EINVAL; 1210 1211 cork->length += size; 1212 if ((size + skb->len > mtu) && 1213 (sk->sk_protocol == IPPROTO_UDP) && 1214 (rt->dst.dev->features & NETIF_F_UFO)) { 1215 skb_shinfo(skb)->gso_size = mtu - fragheaderlen; 1216 skb_shinfo(skb)->gso_type = SKB_GSO_UDP; 1217 } 1218 1219 while (size > 0) { 1220 int i; 1221 1222 if (skb_is_gso(skb)) 1223 len = size; 1224 else { 1225 1226 /* Check if the remaining data fits into current packet. */ 1227 len = mtu - skb->len; 1228 if (len < size) 1229 len = maxfraglen - skb->len; 1230 } 1231 if (len <= 0) { 1232 struct sk_buff *skb_prev; 1233 int alloclen; 1234 1235 skb_prev = skb; 1236 fraggap = skb_prev->len - maxfraglen; 1237 1238 alloclen = fragheaderlen + hh_len + fraggap + 15; 1239 skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation); 1240 if (unlikely(!skb)) { 1241 err = -ENOBUFS; 1242 goto error; 1243 } 1244 1245 /* 1246 * Fill in the control structures 1247 */ 1248 skb->ip_summed = CHECKSUM_NONE; 1249 skb->csum = 0; 1250 skb_reserve(skb, hh_len); 1251 1252 /* 1253 * Find where to start putting bytes. 1254 */ 1255 skb_put(skb, fragheaderlen + fraggap); 1256 skb_reset_network_header(skb); 1257 skb->transport_header = (skb->network_header + 1258 fragheaderlen); 1259 if (fraggap) { 1260 skb->csum = skb_copy_and_csum_bits(skb_prev, 1261 maxfraglen, 1262 skb_transport_header(skb), 1263 fraggap, 0); 1264 skb_prev->csum = csum_sub(skb_prev->csum, 1265 skb->csum); 1266 pskb_trim_unique(skb_prev, maxfraglen); 1267 } 1268 1269 /* 1270 * Put the packet on the pending queue. 1271 */ 1272 __skb_queue_tail(&sk->sk_write_queue, skb); 1273 continue; 1274 } 1275 1276 i = skb_shinfo(skb)->nr_frags; 1277 if (len > size) 1278 len = size; 1279 if (skb_can_coalesce(skb, i, page, offset)) { 1280 skb_frag_size_add(&skb_shinfo(skb)->frags[i-1], len); 1281 } else if (i < MAX_SKB_FRAGS) { 1282 get_page(page); 1283 skb_fill_page_desc(skb, i, page, offset, len); 1284 } else { 1285 err = -EMSGSIZE; 1286 goto error; 1287 } 1288 1289 if (skb->ip_summed == CHECKSUM_NONE) { 1290 __wsum csum; 1291 csum = csum_page(page, offset, len); 1292 skb->csum = csum_block_add(skb->csum, csum, skb->len); 1293 } 1294 1295 skb->len += len; 1296 skb->data_len += len; 1297 skb->truesize += len; 1298 atomic_add(len, &sk->sk_wmem_alloc); 1299 offset += len; 1300 size -= len; 1301 } 1302 return 0; 1303 1304 error: 1305 cork->length -= size; 1306 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS); 1307 return err; 1308 } 1309 1310 static void ip_cork_release(struct inet_cork *cork) 1311 { 1312 cork->flags &= ~IPCORK_OPT; 1313 kfree(cork->opt); 1314 cork->opt = NULL; 1315 dst_release(cork->dst); 1316 cork->dst = NULL; 1317 } 1318 1319 /* 1320 * Combined all pending IP fragments on the socket as one IP datagram 1321 * and push them out. 1322 */ 1323 struct sk_buff *__ip_make_skb(struct sock *sk, 1324 struct flowi4 *fl4, 1325 struct sk_buff_head *queue, 1326 struct inet_cork *cork) 1327 { 1328 struct sk_buff *skb, *tmp_skb; 1329 struct sk_buff **tail_skb; 1330 struct inet_sock *inet = inet_sk(sk); 1331 struct net *net = sock_net(sk); 1332 struct ip_options *opt = NULL; 1333 struct rtable *rt = (struct rtable *)cork->dst; 1334 struct iphdr *iph; 1335 __be16 df = 0; 1336 __u8 ttl; 1337 1338 skb = __skb_dequeue(queue); 1339 if (!skb) 1340 goto out; 1341 tail_skb = &(skb_shinfo(skb)->frag_list); 1342 1343 /* move skb->data to ip header from ext header */ 1344 if (skb->data < skb_network_header(skb)) 1345 __skb_pull(skb, skb_network_offset(skb)); 1346 while ((tmp_skb = __skb_dequeue(queue)) != NULL) { 1347 __skb_pull(tmp_skb, skb_network_header_len(skb)); 1348 *tail_skb = tmp_skb; 1349 tail_skb = &(tmp_skb->next); 1350 skb->len += tmp_skb->len; 1351 skb->data_len += tmp_skb->len; 1352 skb->truesize += tmp_skb->truesize; 1353 tmp_skb->destructor = NULL; 1354 tmp_skb->sk = NULL; 1355 } 1356 1357 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow 1358 * to fragment the frame generated here. No matter, what transforms 1359 * how transforms change size of the packet, it will come out. 1360 */ 1361 skb->ignore_df = ip_sk_ignore_df(sk); 1362 1363 /* DF bit is set when we want to see DF on outgoing frames. 1364 * If ignore_df is set too, we still allow to fragment this frame 1365 * locally. */ 1366 if (inet->pmtudisc == IP_PMTUDISC_DO || 1367 inet->pmtudisc == IP_PMTUDISC_PROBE || 1368 (skb->len <= dst_mtu(&rt->dst) && 1369 ip_dont_fragment(sk, &rt->dst))) 1370 df = htons(IP_DF); 1371 1372 if (cork->flags & IPCORK_OPT) 1373 opt = cork->opt; 1374 1375 if (cork->ttl != 0) 1376 ttl = cork->ttl; 1377 else if (rt->rt_type == RTN_MULTICAST) 1378 ttl = inet->mc_ttl; 1379 else 1380 ttl = ip_select_ttl(inet, &rt->dst); 1381 1382 iph = ip_hdr(skb); 1383 iph->version = 4; 1384 iph->ihl = 5; 1385 iph->tos = (cork->tos != -1) ? cork->tos : inet->tos; 1386 iph->frag_off = df; 1387 iph->ttl = ttl; 1388 iph->protocol = sk->sk_protocol; 1389 ip_copy_addrs(iph, fl4); 1390 ip_select_ident(net, skb, sk); 1391 1392 if (opt) { 1393 iph->ihl += opt->optlen>>2; 1394 ip_options_build(skb, opt, cork->addr, rt, 0); 1395 } 1396 1397 skb->priority = (cork->tos != -1) ? cork->priority: sk->sk_priority; 1398 skb->mark = sk->sk_mark; 1399 /* 1400 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec 1401 * on dst refcount 1402 */ 1403 cork->dst = NULL; 1404 skb_dst_set(skb, &rt->dst); 1405 1406 if (iph->protocol == IPPROTO_ICMP) 1407 icmp_out_count(net, ((struct icmphdr *) 1408 skb_transport_header(skb))->type); 1409 1410 ip_cork_release(cork); 1411 out: 1412 return skb; 1413 } 1414 1415 int ip_send_skb(struct net *net, struct sk_buff *skb) 1416 { 1417 int err; 1418 1419 err = ip_local_out(skb); 1420 if (err) { 1421 if (err > 0) 1422 err = net_xmit_errno(err); 1423 if (err) 1424 IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS); 1425 } 1426 1427 return err; 1428 } 1429 1430 int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4) 1431 { 1432 struct sk_buff *skb; 1433 1434 skb = ip_finish_skb(sk, fl4); 1435 if (!skb) 1436 return 0; 1437 1438 /* Netfilter gets whole the not fragmented skb. */ 1439 return ip_send_skb(sock_net(sk), skb); 1440 } 1441 1442 /* 1443 * Throw away all pending data on the socket. 1444 */ 1445 static void __ip_flush_pending_frames(struct sock *sk, 1446 struct sk_buff_head *queue, 1447 struct inet_cork *cork) 1448 { 1449 struct sk_buff *skb; 1450 1451 while ((skb = __skb_dequeue_tail(queue)) != NULL) 1452 kfree_skb(skb); 1453 1454 ip_cork_release(cork); 1455 } 1456 1457 void ip_flush_pending_frames(struct sock *sk) 1458 { 1459 __ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork.base); 1460 } 1461 1462 struct sk_buff *ip_make_skb(struct sock *sk, 1463 struct flowi4 *fl4, 1464 int getfrag(void *from, char *to, int offset, 1465 int len, int odd, struct sk_buff *skb), 1466 void *from, int length, int transhdrlen, 1467 struct ipcm_cookie *ipc, struct rtable **rtp, 1468 unsigned int flags) 1469 { 1470 struct inet_cork cork; 1471 struct sk_buff_head queue; 1472 int err; 1473 1474 if (flags & MSG_PROBE) 1475 return NULL; 1476 1477 __skb_queue_head_init(&queue); 1478 1479 cork.flags = 0; 1480 cork.addr = 0; 1481 cork.opt = NULL; 1482 err = ip_setup_cork(sk, &cork, ipc, rtp); 1483 if (err) 1484 return ERR_PTR(err); 1485 1486 err = __ip_append_data(sk, fl4, &queue, &cork, 1487 ¤t->task_frag, getfrag, 1488 from, length, transhdrlen, flags); 1489 if (err) { 1490 __ip_flush_pending_frames(sk, &queue, &cork); 1491 return ERR_PTR(err); 1492 } 1493 1494 return __ip_make_skb(sk, fl4, &queue, &cork); 1495 } 1496 1497 /* 1498 * Fetch data from kernel space and fill in checksum if needed. 1499 */ 1500 static int ip_reply_glue_bits(void *dptr, char *to, int offset, 1501 int len, int odd, struct sk_buff *skb) 1502 { 1503 __wsum csum; 1504 1505 csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0); 1506 skb->csum = csum_block_add(skb->csum, csum, odd); 1507 return 0; 1508 } 1509 1510 /* 1511 * Generic function to send a packet as reply to another packet. 1512 * Used to send some TCP resets/acks so far. 1513 */ 1514 void ip_send_unicast_reply(struct sock *sk, struct sk_buff *skb, 1515 const struct ip_options *sopt, 1516 __be32 daddr, __be32 saddr, 1517 const struct ip_reply_arg *arg, 1518 unsigned int len) 1519 { 1520 struct ip_options_data replyopts; 1521 struct ipcm_cookie ipc; 1522 struct flowi4 fl4; 1523 struct rtable *rt = skb_rtable(skb); 1524 struct net *net = sock_net(sk); 1525 struct sk_buff *nskb; 1526 int err; 1527 1528 if (__ip_options_echo(&replyopts.opt.opt, skb, sopt)) 1529 return; 1530 1531 ipc.addr = daddr; 1532 ipc.opt = NULL; 1533 ipc.tx_flags = 0; 1534 ipc.ttl = 0; 1535 ipc.tos = -1; 1536 1537 if (replyopts.opt.opt.optlen) { 1538 ipc.opt = &replyopts.opt; 1539 1540 if (replyopts.opt.opt.srr) 1541 daddr = replyopts.opt.opt.faddr; 1542 } 1543 1544 flowi4_init_output(&fl4, arg->bound_dev_if, 1545 IP4_REPLY_MARK(net, skb->mark), 1546 RT_TOS(arg->tos), 1547 RT_SCOPE_UNIVERSE, ip_hdr(skb)->protocol, 1548 ip_reply_arg_flowi_flags(arg), 1549 daddr, saddr, 1550 tcp_hdr(skb)->source, tcp_hdr(skb)->dest); 1551 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4)); 1552 rt = ip_route_output_key(net, &fl4); 1553 if (IS_ERR(rt)) 1554 return; 1555 1556 inet_sk(sk)->tos = arg->tos; 1557 1558 sk->sk_priority = skb->priority; 1559 sk->sk_protocol = ip_hdr(skb)->protocol; 1560 sk->sk_bound_dev_if = arg->bound_dev_if; 1561 sk->sk_sndbuf = sysctl_wmem_default; 1562 err = ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base, 1563 len, 0, &ipc, &rt, MSG_DONTWAIT); 1564 if (unlikely(err)) { 1565 ip_flush_pending_frames(sk); 1566 goto out; 1567 } 1568 1569 nskb = skb_peek(&sk->sk_write_queue); 1570 if (nskb) { 1571 if (arg->csumoffset >= 0) 1572 *((__sum16 *)skb_transport_header(nskb) + 1573 arg->csumoffset) = csum_fold(csum_add(nskb->csum, 1574 arg->csum)); 1575 nskb->ip_summed = CHECKSUM_NONE; 1576 skb_set_queue_mapping(nskb, skb_get_queue_mapping(skb)); 1577 ip_push_pending_frames(sk, &fl4); 1578 } 1579 out: 1580 ip_rt_put(rt); 1581 } 1582 1583 void __init ip_init(void) 1584 { 1585 ip_rt_init(); 1586 inet_initpeers(); 1587 1588 #if defined(CONFIG_IP_MULTICAST) 1589 igmp_mc_init(); 1590 #endif 1591 } 1592