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 <asm/system.h> 47 #include <linux/module.h> 48 #include <linux/types.h> 49 #include <linux/kernel.h> 50 #include <linux/mm.h> 51 #include <linux/string.h> 52 #include <linux/errno.h> 53 #include <linux/highmem.h> 54 #include <linux/slab.h> 55 56 #include <linux/socket.h> 57 #include <linux/sockios.h> 58 #include <linux/in.h> 59 #include <linux/inet.h> 60 #include <linux/netdevice.h> 61 #include <linux/etherdevice.h> 62 #include <linux/proc_fs.h> 63 #include <linux/stat.h> 64 #include <linux/init.h> 65 66 #include <net/snmp.h> 67 #include <net/ip.h> 68 #include <net/protocol.h> 69 #include <net/route.h> 70 #include <net/xfrm.h> 71 #include <linux/skbuff.h> 72 #include <net/sock.h> 73 #include <net/arp.h> 74 #include <net/icmp.h> 75 #include <net/checksum.h> 76 #include <net/inetpeer.h> 77 #include <linux/igmp.h> 78 #include <linux/netfilter_ipv4.h> 79 #include <linux/netfilter_bridge.h> 80 #include <linux/mroute.h> 81 #include <linux/netlink.h> 82 #include <linux/tcp.h> 83 84 int sysctl_ip_default_ttl __read_mostly = IPDEFTTL; 85 86 /* Generate a checksum for an outgoing IP datagram. */ 87 __inline__ 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 93 int __ip_local_out(struct sk_buff *skb) 94 { 95 struct iphdr *iph = ip_hdr(skb); 96 97 iph->tot_len = htons(skb->len); 98 ip_send_check(iph); 99 return nf_hook(NFPROTO_IPV4, NF_INET_LOCAL_OUT, skb, NULL, 100 skb_dst(skb)->dev, dst_output); 101 } 102 103 int ip_local_out(struct sk_buff *skb) 104 { 105 int err; 106 107 err = __ip_local_out(skb); 108 if (likely(err == 1)) 109 err = dst_output(skb); 110 111 return err; 112 } 113 EXPORT_SYMBOL_GPL(ip_local_out); 114 115 /* dev_loopback_xmit for use with netfilter. */ 116 static int ip_dev_loopback_xmit(struct sk_buff *newskb) 117 { 118 skb_reset_mac_header(newskb); 119 __skb_pull(newskb, skb_network_offset(newskb)); 120 newskb->pkt_type = PACKET_LOOPBACK; 121 newskb->ip_summed = CHECKSUM_UNNECESSARY; 122 WARN_ON(!skb_dst(newskb)); 123 netif_rx_ni(newskb); 124 return 0; 125 } 126 127 static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst) 128 { 129 int ttl = inet->uc_ttl; 130 131 if (ttl < 0) 132 ttl = dst_metric(dst, RTAX_HOPLIMIT); 133 return ttl; 134 } 135 136 /* 137 * Add an ip header to a skbuff and send it out. 138 * 139 */ 140 int ip_build_and_send_pkt(struct sk_buff *skb, struct sock *sk, 141 __be32 saddr, __be32 daddr, struct ip_options *opt) 142 { 143 struct inet_sock *inet = inet_sk(sk); 144 struct rtable *rt = skb_rtable(skb); 145 struct iphdr *iph; 146 147 /* Build the IP header. */ 148 skb_push(skb, sizeof(struct iphdr) + (opt ? opt->optlen : 0)); 149 skb_reset_network_header(skb); 150 iph = ip_hdr(skb); 151 iph->version = 4; 152 iph->ihl = 5; 153 iph->tos = inet->tos; 154 if (ip_dont_fragment(sk, &rt->u.dst)) 155 iph->frag_off = htons(IP_DF); 156 else 157 iph->frag_off = 0; 158 iph->ttl = ip_select_ttl(inet, &rt->u.dst); 159 iph->daddr = rt->rt_dst; 160 iph->saddr = rt->rt_src; 161 iph->protocol = sk->sk_protocol; 162 ip_select_ident(iph, &rt->u.dst, sk); 163 164 if (opt && opt->optlen) { 165 iph->ihl += opt->optlen>>2; 166 ip_options_build(skb, opt, daddr, rt, 0); 167 } 168 169 skb->priority = sk->sk_priority; 170 skb->mark = sk->sk_mark; 171 172 /* Send it out. */ 173 return ip_local_out(skb); 174 } 175 176 EXPORT_SYMBOL_GPL(ip_build_and_send_pkt); 177 178 static inline int ip_finish_output2(struct sk_buff *skb) 179 { 180 struct dst_entry *dst = skb_dst(skb); 181 struct rtable *rt = (struct rtable *)dst; 182 struct net_device *dev = dst->dev; 183 unsigned int hh_len = LL_RESERVED_SPACE(dev); 184 185 if (rt->rt_type == RTN_MULTICAST) { 186 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUTMCAST, skb->len); 187 } else if (rt->rt_type == RTN_BROADCAST) 188 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUTBCAST, skb->len); 189 190 /* Be paranoid, rather than too clever. */ 191 if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) { 192 struct sk_buff *skb2; 193 194 skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev)); 195 if (skb2 == NULL) { 196 kfree_skb(skb); 197 return -ENOMEM; 198 } 199 if (skb->sk) 200 skb_set_owner_w(skb2, skb->sk); 201 kfree_skb(skb); 202 skb = skb2; 203 } 204 205 if (dst->hh) 206 return neigh_hh_output(dst->hh, skb); 207 else if (dst->neighbour) 208 return dst->neighbour->output(skb); 209 210 if (net_ratelimit()) 211 printk(KERN_DEBUG "ip_finish_output2: No header cache and no neighbour!\n"); 212 kfree_skb(skb); 213 return -EINVAL; 214 } 215 216 static inline int ip_skb_dst_mtu(struct sk_buff *skb) 217 { 218 struct inet_sock *inet = skb->sk ? inet_sk(skb->sk) : NULL; 219 220 return (inet && inet->pmtudisc == IP_PMTUDISC_PROBE) ? 221 skb_dst(skb)->dev->mtu : dst_mtu(skb_dst(skb)); 222 } 223 224 static int ip_finish_output(struct sk_buff *skb) 225 { 226 #if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM) 227 /* Policy lookup after SNAT yielded a new policy */ 228 if (skb_dst(skb)->xfrm != NULL) { 229 IPCB(skb)->flags |= IPSKB_REROUTED; 230 return dst_output(skb); 231 } 232 #endif 233 if (skb->len > ip_skb_dst_mtu(skb) && !skb_is_gso(skb)) 234 return ip_fragment(skb, ip_finish_output2); 235 else 236 return ip_finish_output2(skb); 237 } 238 239 int ip_mc_output(struct sk_buff *skb) 240 { 241 struct sock *sk = skb->sk; 242 struct rtable *rt = skb_rtable(skb); 243 struct net_device *dev = rt->u.dst.dev; 244 245 /* 246 * If the indicated interface is up and running, send the packet. 247 */ 248 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len); 249 250 skb->dev = dev; 251 skb->protocol = htons(ETH_P_IP); 252 253 /* 254 * Multicasts are looped back for other local users 255 */ 256 257 if (rt->rt_flags&RTCF_MULTICAST) { 258 if (sk_mc_loop(sk) 259 #ifdef CONFIG_IP_MROUTE 260 /* Small optimization: do not loopback not local frames, 261 which returned after forwarding; they will be dropped 262 by ip_mr_input in any case. 263 Note, that local frames are looped back to be delivered 264 to local recipients. 265 266 This check is duplicated in ip_mr_input at the moment. 267 */ 268 && 269 ((rt->rt_flags & RTCF_LOCAL) || 270 !(IPCB(skb)->flags & IPSKB_FORWARDED)) 271 #endif 272 ) { 273 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC); 274 if (newskb) 275 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, 276 newskb, NULL, newskb->dev, 277 ip_dev_loopback_xmit); 278 } 279 280 /* Multicasts with ttl 0 must not go beyond the host */ 281 282 if (ip_hdr(skb)->ttl == 0) { 283 kfree_skb(skb); 284 return 0; 285 } 286 } 287 288 if (rt->rt_flags&RTCF_BROADCAST) { 289 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC); 290 if (newskb) 291 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, newskb, 292 NULL, newskb->dev, ip_dev_loopback_xmit); 293 } 294 295 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb, NULL, 296 skb->dev, ip_finish_output, 297 !(IPCB(skb)->flags & IPSKB_REROUTED)); 298 } 299 300 int ip_output(struct sk_buff *skb) 301 { 302 struct net_device *dev = skb_dst(skb)->dev; 303 304 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len); 305 306 skb->dev = dev; 307 skb->protocol = htons(ETH_P_IP); 308 309 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb, NULL, dev, 310 ip_finish_output, 311 !(IPCB(skb)->flags & IPSKB_REROUTED)); 312 } 313 314 int ip_queue_xmit(struct sk_buff *skb) 315 { 316 struct sock *sk = skb->sk; 317 struct inet_sock *inet = inet_sk(sk); 318 struct ip_options *opt = inet->opt; 319 struct rtable *rt; 320 struct iphdr *iph; 321 int res; 322 323 /* Skip all of this if the packet is already routed, 324 * f.e. by something like SCTP. 325 */ 326 rcu_read_lock(); 327 rt = skb_rtable(skb); 328 if (rt != NULL) 329 goto packet_routed; 330 331 /* Make sure we can route this packet. */ 332 rt = (struct rtable *)__sk_dst_check(sk, 0); 333 if (rt == NULL) { 334 __be32 daddr; 335 336 /* Use correct destination address if we have options. */ 337 daddr = inet->inet_daddr; 338 if(opt && opt->srr) 339 daddr = opt->faddr; 340 341 { 342 struct flowi fl = { .oif = sk->sk_bound_dev_if, 343 .mark = sk->sk_mark, 344 .nl_u = { .ip4_u = 345 { .daddr = daddr, 346 .saddr = inet->inet_saddr, 347 .tos = RT_CONN_FLAGS(sk) } }, 348 .proto = sk->sk_protocol, 349 .flags = inet_sk_flowi_flags(sk), 350 .uli_u = { .ports = 351 { .sport = inet->inet_sport, 352 .dport = inet->inet_dport } } }; 353 354 /* If this fails, retransmit mechanism of transport layer will 355 * keep trying until route appears or the connection times 356 * itself out. 357 */ 358 security_sk_classify_flow(sk, &fl); 359 if (ip_route_output_flow(sock_net(sk), &rt, &fl, sk, 0)) 360 goto no_route; 361 } 362 sk_setup_caps(sk, &rt->u.dst); 363 } 364 skb_dst_set_noref(skb, &rt->u.dst); 365 366 packet_routed: 367 if (opt && opt->is_strictroute && rt->rt_dst != rt->rt_gateway) 368 goto no_route; 369 370 /* OK, we know where to send it, allocate and build IP header. */ 371 skb_push(skb, sizeof(struct iphdr) + (opt ? opt->optlen : 0)); 372 skb_reset_network_header(skb); 373 iph = ip_hdr(skb); 374 *((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (inet->tos & 0xff)); 375 if (ip_dont_fragment(sk, &rt->u.dst) && !skb->local_df) 376 iph->frag_off = htons(IP_DF); 377 else 378 iph->frag_off = 0; 379 iph->ttl = ip_select_ttl(inet, &rt->u.dst); 380 iph->protocol = sk->sk_protocol; 381 iph->saddr = rt->rt_src; 382 iph->daddr = rt->rt_dst; 383 /* Transport layer set skb->h.foo itself. */ 384 385 if (opt && opt->optlen) { 386 iph->ihl += opt->optlen >> 2; 387 ip_options_build(skb, opt, inet->inet_daddr, rt, 0); 388 } 389 390 ip_select_ident_more(iph, &rt->u.dst, sk, 391 (skb_shinfo(skb)->gso_segs ?: 1) - 1); 392 393 skb->priority = sk->sk_priority; 394 skb->mark = sk->sk_mark; 395 396 res = ip_local_out(skb); 397 rcu_read_unlock(); 398 return res; 399 400 no_route: 401 rcu_read_unlock(); 402 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES); 403 kfree_skb(skb); 404 return -EHOSTUNREACH; 405 } 406 407 408 static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from) 409 { 410 to->pkt_type = from->pkt_type; 411 to->priority = from->priority; 412 to->protocol = from->protocol; 413 skb_dst_drop(to); 414 skb_dst_set(to, dst_clone(skb_dst(from))); 415 to->dev = from->dev; 416 to->mark = from->mark; 417 418 /* Copy the flags to each fragment. */ 419 IPCB(to)->flags = IPCB(from)->flags; 420 421 #ifdef CONFIG_NET_SCHED 422 to->tc_index = from->tc_index; 423 #endif 424 nf_copy(to, from); 425 #if defined(CONFIG_NETFILTER_XT_TARGET_TRACE) || \ 426 defined(CONFIG_NETFILTER_XT_TARGET_TRACE_MODULE) 427 to->nf_trace = from->nf_trace; 428 #endif 429 #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE) 430 to->ipvs_property = from->ipvs_property; 431 #endif 432 skb_copy_secmark(to, from); 433 } 434 435 /* 436 * This IP datagram is too large to be sent in one piece. Break it up into 437 * smaller pieces (each of size equal to IP header plus 438 * a block of the data of the original IP data part) that will yet fit in a 439 * single device frame, and queue such a frame for sending. 440 */ 441 442 int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *)) 443 { 444 struct iphdr *iph; 445 int raw = 0; 446 int ptr; 447 struct net_device *dev; 448 struct sk_buff *skb2; 449 unsigned int mtu, hlen, left, len, ll_rs, pad; 450 int offset; 451 __be16 not_last_frag; 452 struct rtable *rt = skb_rtable(skb); 453 int err = 0; 454 455 dev = rt->u.dst.dev; 456 457 /* 458 * Point into the IP datagram header. 459 */ 460 461 iph = ip_hdr(skb); 462 463 if (unlikely((iph->frag_off & htons(IP_DF)) && !skb->local_df)) { 464 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); 465 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, 466 htonl(ip_skb_dst_mtu(skb))); 467 kfree_skb(skb); 468 return -EMSGSIZE; 469 } 470 471 /* 472 * Setup starting values. 473 */ 474 475 hlen = iph->ihl * 4; 476 mtu = dst_mtu(&rt->u.dst) - hlen; /* Size of data space */ 477 #ifdef CONFIG_BRIDGE_NETFILTER 478 if (skb->nf_bridge) 479 mtu -= nf_bridge_mtu_reduction(skb); 480 #endif 481 IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE; 482 483 /* When frag_list is given, use it. First, check its validity: 484 * some transformers could create wrong frag_list or break existing 485 * one, it is not prohibited. In this case fall back to copying. 486 * 487 * LATER: this step can be merged to real generation of fragments, 488 * we can switch to copy when see the first bad fragment. 489 */ 490 if (skb_has_frags(skb)) { 491 struct sk_buff *frag; 492 int first_len = skb_pagelen(skb); 493 int truesizes = 0; 494 495 if (first_len - hlen > mtu || 496 ((first_len - hlen) & 7) || 497 (iph->frag_off & htons(IP_MF|IP_OFFSET)) || 498 skb_cloned(skb)) 499 goto slow_path; 500 501 skb_walk_frags(skb, frag) { 502 /* Correct geometry. */ 503 if (frag->len > mtu || 504 ((frag->len & 7) && frag->next) || 505 skb_headroom(frag) < hlen) 506 goto slow_path; 507 508 /* Partially cloned skb? */ 509 if (skb_shared(frag)) 510 goto slow_path; 511 512 BUG_ON(frag->sk); 513 if (skb->sk) { 514 frag->sk = skb->sk; 515 frag->destructor = sock_wfree; 516 } 517 truesizes += frag->truesize; 518 } 519 520 /* Everything is OK. Generate! */ 521 522 err = 0; 523 offset = 0; 524 frag = skb_shinfo(skb)->frag_list; 525 skb_frag_list_init(skb); 526 skb->data_len = first_len - skb_headlen(skb); 527 skb->truesize -= truesizes; 528 skb->len = first_len; 529 iph->tot_len = htons(first_len); 530 iph->frag_off = htons(IP_MF); 531 ip_send_check(iph); 532 533 for (;;) { 534 /* Prepare header of the next frame, 535 * before previous one went down. */ 536 if (frag) { 537 frag->ip_summed = CHECKSUM_NONE; 538 skb_reset_transport_header(frag); 539 __skb_push(frag, hlen); 540 skb_reset_network_header(frag); 541 memcpy(skb_network_header(frag), iph, hlen); 542 iph = ip_hdr(frag); 543 iph->tot_len = htons(frag->len); 544 ip_copy_metadata(frag, skb); 545 if (offset == 0) 546 ip_options_fragment(frag); 547 offset += skb->len - hlen; 548 iph->frag_off = htons(offset>>3); 549 if (frag->next != NULL) 550 iph->frag_off |= htons(IP_MF); 551 /* Ready, complete checksum */ 552 ip_send_check(iph); 553 } 554 555 err = output(skb); 556 557 if (!err) 558 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES); 559 if (err || !frag) 560 break; 561 562 skb = frag; 563 frag = skb->next; 564 skb->next = NULL; 565 } 566 567 if (err == 0) { 568 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS); 569 return 0; 570 } 571 572 while (frag) { 573 skb = frag->next; 574 kfree_skb(frag); 575 frag = skb; 576 } 577 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); 578 return err; 579 } 580 581 slow_path: 582 left = skb->len - hlen; /* Space per frame */ 583 ptr = raw + hlen; /* Where to start from */ 584 585 /* for bridged IP traffic encapsulated inside f.e. a vlan header, 586 * we need to make room for the encapsulating header 587 */ 588 pad = nf_bridge_pad(skb); 589 ll_rs = LL_RESERVED_SPACE_EXTRA(rt->u.dst.dev, pad); 590 mtu -= pad; 591 592 /* 593 * Fragment the datagram. 594 */ 595 596 offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3; 597 not_last_frag = iph->frag_off & htons(IP_MF); 598 599 /* 600 * Keep copying data until we run out. 601 */ 602 603 while (left > 0) { 604 len = left; 605 /* IF: it doesn't fit, use 'mtu' - the data space left */ 606 if (len > mtu) 607 len = mtu; 608 /* IF: we are not sending upto and including the packet end 609 then align the next start on an eight byte boundary */ 610 if (len < left) { 611 len &= ~7; 612 } 613 /* 614 * Allocate buffer. 615 */ 616 617 if ((skb2 = alloc_skb(len+hlen+ll_rs, GFP_ATOMIC)) == NULL) { 618 NETDEBUG(KERN_INFO "IP: frag: no memory for new fragment!\n"); 619 err = -ENOMEM; 620 goto fail; 621 } 622 623 /* 624 * Set up data on packet 625 */ 626 627 ip_copy_metadata(skb2, skb); 628 skb_reserve(skb2, ll_rs); 629 skb_put(skb2, len + hlen); 630 skb_reset_network_header(skb2); 631 skb2->transport_header = skb2->network_header + hlen; 632 633 /* 634 * Charge the memory for the fragment to any owner 635 * it might possess 636 */ 637 638 if (skb->sk) 639 skb_set_owner_w(skb2, skb->sk); 640 641 /* 642 * Copy the packet header into the new buffer. 643 */ 644 645 skb_copy_from_linear_data(skb, skb_network_header(skb2), hlen); 646 647 /* 648 * Copy a block of the IP datagram. 649 */ 650 if (skb_copy_bits(skb, ptr, skb_transport_header(skb2), len)) 651 BUG(); 652 left -= len; 653 654 /* 655 * Fill in the new header fields. 656 */ 657 iph = ip_hdr(skb2); 658 iph->frag_off = htons((offset >> 3)); 659 660 /* ANK: dirty, but effective trick. Upgrade options only if 661 * the segment to be fragmented was THE FIRST (otherwise, 662 * options are already fixed) and make it ONCE 663 * on the initial skb, so that all the following fragments 664 * will inherit fixed options. 665 */ 666 if (offset == 0) 667 ip_options_fragment(skb); 668 669 /* 670 * Added AC : If we are fragmenting a fragment that's not the 671 * last fragment then keep MF on each bit 672 */ 673 if (left > 0 || not_last_frag) 674 iph->frag_off |= htons(IP_MF); 675 ptr += len; 676 offset += len; 677 678 /* 679 * Put this fragment into the sending queue. 680 */ 681 iph->tot_len = htons(len + hlen); 682 683 ip_send_check(iph); 684 685 err = output(skb2); 686 if (err) 687 goto fail; 688 689 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES); 690 } 691 kfree_skb(skb); 692 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS); 693 return err; 694 695 fail: 696 kfree_skb(skb); 697 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); 698 return err; 699 } 700 701 EXPORT_SYMBOL(ip_fragment); 702 703 int 704 ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb) 705 { 706 struct iovec *iov = from; 707 708 if (skb->ip_summed == CHECKSUM_PARTIAL) { 709 if (memcpy_fromiovecend(to, iov, offset, len) < 0) 710 return -EFAULT; 711 } else { 712 __wsum csum = 0; 713 if (csum_partial_copy_fromiovecend(to, iov, offset, len, &csum) < 0) 714 return -EFAULT; 715 skb->csum = csum_block_add(skb->csum, csum, odd); 716 } 717 return 0; 718 } 719 720 static inline __wsum 721 csum_page(struct page *page, int offset, int copy) 722 { 723 char *kaddr; 724 __wsum csum; 725 kaddr = kmap(page); 726 csum = csum_partial(kaddr + offset, copy, 0); 727 kunmap(page); 728 return csum; 729 } 730 731 static inline int ip_ufo_append_data(struct sock *sk, 732 int getfrag(void *from, char *to, int offset, int len, 733 int odd, struct sk_buff *skb), 734 void *from, int length, int hh_len, int fragheaderlen, 735 int transhdrlen, int mtu, unsigned int flags) 736 { 737 struct sk_buff *skb; 738 int err; 739 740 /* There is support for UDP fragmentation offload by network 741 * device, so create one single skb packet containing complete 742 * udp datagram 743 */ 744 if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL) { 745 skb = sock_alloc_send_skb(sk, 746 hh_len + fragheaderlen + transhdrlen + 20, 747 (flags & MSG_DONTWAIT), &err); 748 749 if (skb == NULL) 750 return err; 751 752 /* reserve space for Hardware header */ 753 skb_reserve(skb, hh_len); 754 755 /* create space for UDP/IP header */ 756 skb_put(skb, fragheaderlen + transhdrlen); 757 758 /* initialize network header pointer */ 759 skb_reset_network_header(skb); 760 761 /* initialize protocol header pointer */ 762 skb->transport_header = skb->network_header + fragheaderlen; 763 764 skb->ip_summed = CHECKSUM_PARTIAL; 765 skb->csum = 0; 766 sk->sk_sndmsg_off = 0; 767 768 /* specify the length of each IP datagram fragment */ 769 skb_shinfo(skb)->gso_size = mtu - fragheaderlen; 770 skb_shinfo(skb)->gso_type = SKB_GSO_UDP; 771 __skb_queue_tail(&sk->sk_write_queue, skb); 772 } 773 774 return skb_append_datato_frags(sk, skb, getfrag, from, 775 (length - transhdrlen)); 776 } 777 778 /* 779 * ip_append_data() and ip_append_page() can make one large IP datagram 780 * from many pieces of data. Each pieces will be holded on the socket 781 * until ip_push_pending_frames() is called. Each piece can be a page 782 * or non-page data. 783 * 784 * Not only UDP, other transport protocols - e.g. raw sockets - can use 785 * this interface potentially. 786 * 787 * LATER: length must be adjusted by pad at tail, when it is required. 788 */ 789 int ip_append_data(struct sock *sk, 790 int getfrag(void *from, char *to, int offset, int len, 791 int odd, struct sk_buff *skb), 792 void *from, int length, int transhdrlen, 793 struct ipcm_cookie *ipc, struct rtable **rtp, 794 unsigned int flags) 795 { 796 struct inet_sock *inet = inet_sk(sk); 797 struct sk_buff *skb; 798 799 struct ip_options *opt = NULL; 800 int hh_len; 801 int exthdrlen; 802 int mtu; 803 int copy; 804 int err; 805 int offset = 0; 806 unsigned int maxfraglen, fragheaderlen; 807 int csummode = CHECKSUM_NONE; 808 struct rtable *rt; 809 810 if (flags&MSG_PROBE) 811 return 0; 812 813 if (skb_queue_empty(&sk->sk_write_queue)) { 814 /* 815 * setup for corking. 816 */ 817 opt = ipc->opt; 818 if (opt) { 819 if (inet->cork.opt == NULL) { 820 inet->cork.opt = kmalloc(sizeof(struct ip_options) + 40, sk->sk_allocation); 821 if (unlikely(inet->cork.opt == NULL)) 822 return -ENOBUFS; 823 } 824 memcpy(inet->cork.opt, opt, sizeof(struct ip_options)+opt->optlen); 825 inet->cork.flags |= IPCORK_OPT; 826 inet->cork.addr = ipc->addr; 827 } 828 rt = *rtp; 829 if (unlikely(!rt)) 830 return -EFAULT; 831 /* 832 * We steal reference to this route, caller should not release it 833 */ 834 *rtp = NULL; 835 inet->cork.fragsize = mtu = inet->pmtudisc == IP_PMTUDISC_PROBE ? 836 rt->u.dst.dev->mtu : 837 dst_mtu(rt->u.dst.path); 838 inet->cork.dst = &rt->u.dst; 839 inet->cork.length = 0; 840 sk->sk_sndmsg_page = NULL; 841 sk->sk_sndmsg_off = 0; 842 if ((exthdrlen = rt->u.dst.header_len) != 0) { 843 length += exthdrlen; 844 transhdrlen += exthdrlen; 845 } 846 } else { 847 rt = (struct rtable *)inet->cork.dst; 848 if (inet->cork.flags & IPCORK_OPT) 849 opt = inet->cork.opt; 850 851 transhdrlen = 0; 852 exthdrlen = 0; 853 mtu = inet->cork.fragsize; 854 } 855 hh_len = LL_RESERVED_SPACE(rt->u.dst.dev); 856 857 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0); 858 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen; 859 860 if (inet->cork.length + length > 0xFFFF - fragheaderlen) { 861 ip_local_error(sk, EMSGSIZE, rt->rt_dst, inet->inet_dport, 862 mtu-exthdrlen); 863 return -EMSGSIZE; 864 } 865 866 /* 867 * transhdrlen > 0 means that this is the first fragment and we wish 868 * it won't be fragmented in the future. 869 */ 870 if (transhdrlen && 871 length + fragheaderlen <= mtu && 872 rt->u.dst.dev->features & NETIF_F_V4_CSUM && 873 !exthdrlen) 874 csummode = CHECKSUM_PARTIAL; 875 876 inet->cork.length += length; 877 if (((length> mtu) || !skb_queue_empty(&sk->sk_write_queue)) && 878 (sk->sk_protocol == IPPROTO_UDP) && 879 (rt->u.dst.dev->features & NETIF_F_UFO)) { 880 err = ip_ufo_append_data(sk, getfrag, from, length, hh_len, 881 fragheaderlen, transhdrlen, mtu, 882 flags); 883 if (err) 884 goto error; 885 return 0; 886 } 887 888 /* So, what's going on in the loop below? 889 * 890 * We use calculated fragment length to generate chained skb, 891 * each of segments is IP fragment ready for sending to network after 892 * adding appropriate IP header. 893 */ 894 895 if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL) 896 goto alloc_new_skb; 897 898 while (length > 0) { 899 /* Check if the remaining data fits into current packet. */ 900 copy = mtu - skb->len; 901 if (copy < length) 902 copy = maxfraglen - skb->len; 903 if (copy <= 0) { 904 char *data; 905 unsigned int datalen; 906 unsigned int fraglen; 907 unsigned int fraggap; 908 unsigned int alloclen; 909 struct sk_buff *skb_prev; 910 alloc_new_skb: 911 skb_prev = skb; 912 if (skb_prev) 913 fraggap = skb_prev->len - maxfraglen; 914 else 915 fraggap = 0; 916 917 /* 918 * If remaining data exceeds the mtu, 919 * we know we need more fragment(s). 920 */ 921 datalen = length + fraggap; 922 if (datalen > mtu - fragheaderlen) 923 datalen = maxfraglen - fragheaderlen; 924 fraglen = datalen + fragheaderlen; 925 926 if ((flags & MSG_MORE) && 927 !(rt->u.dst.dev->features&NETIF_F_SG)) 928 alloclen = mtu; 929 else 930 alloclen = datalen + fragheaderlen; 931 932 /* The last fragment gets additional space at tail. 933 * Note, with MSG_MORE we overallocate on fragments, 934 * because we have no idea what fragment will be 935 * the last. 936 */ 937 if (datalen == length + fraggap) 938 alloclen += rt->u.dst.trailer_len; 939 940 if (transhdrlen) { 941 skb = sock_alloc_send_skb(sk, 942 alloclen + hh_len + 15, 943 (flags & MSG_DONTWAIT), &err); 944 } else { 945 skb = NULL; 946 if (atomic_read(&sk->sk_wmem_alloc) <= 947 2 * sk->sk_sndbuf) 948 skb = sock_wmalloc(sk, 949 alloclen + hh_len + 15, 1, 950 sk->sk_allocation); 951 if (unlikely(skb == NULL)) 952 err = -ENOBUFS; 953 else 954 /* only the initial fragment is 955 time stamped */ 956 ipc->shtx.flags = 0; 957 } 958 if (skb == NULL) 959 goto error; 960 961 /* 962 * Fill in the control structures 963 */ 964 skb->ip_summed = csummode; 965 skb->csum = 0; 966 skb_reserve(skb, hh_len); 967 *skb_tx(skb) = ipc->shtx; 968 969 /* 970 * Find where to start putting bytes. 971 */ 972 data = skb_put(skb, fraglen); 973 skb_set_network_header(skb, exthdrlen); 974 skb->transport_header = (skb->network_header + 975 fragheaderlen); 976 data += fragheaderlen; 977 978 if (fraggap) { 979 skb->csum = skb_copy_and_csum_bits( 980 skb_prev, maxfraglen, 981 data + transhdrlen, fraggap, 0); 982 skb_prev->csum = csum_sub(skb_prev->csum, 983 skb->csum); 984 data += fraggap; 985 pskb_trim_unique(skb_prev, maxfraglen); 986 } 987 988 copy = datalen - transhdrlen - fraggap; 989 if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) { 990 err = -EFAULT; 991 kfree_skb(skb); 992 goto error; 993 } 994 995 offset += copy; 996 length -= datalen - fraggap; 997 transhdrlen = 0; 998 exthdrlen = 0; 999 csummode = CHECKSUM_NONE; 1000 1001 /* 1002 * Put the packet on the pending queue. 1003 */ 1004 __skb_queue_tail(&sk->sk_write_queue, skb); 1005 continue; 1006 } 1007 1008 if (copy > length) 1009 copy = length; 1010 1011 if (!(rt->u.dst.dev->features&NETIF_F_SG)) { 1012 unsigned int off; 1013 1014 off = skb->len; 1015 if (getfrag(from, skb_put(skb, copy), 1016 offset, copy, off, skb) < 0) { 1017 __skb_trim(skb, off); 1018 err = -EFAULT; 1019 goto error; 1020 } 1021 } else { 1022 int i = skb_shinfo(skb)->nr_frags; 1023 skb_frag_t *frag = &skb_shinfo(skb)->frags[i-1]; 1024 struct page *page = sk->sk_sndmsg_page; 1025 int off = sk->sk_sndmsg_off; 1026 unsigned int left; 1027 1028 if (page && (left = PAGE_SIZE - off) > 0) { 1029 if (copy >= left) 1030 copy = left; 1031 if (page != frag->page) { 1032 if (i == MAX_SKB_FRAGS) { 1033 err = -EMSGSIZE; 1034 goto error; 1035 } 1036 get_page(page); 1037 skb_fill_page_desc(skb, i, page, sk->sk_sndmsg_off, 0); 1038 frag = &skb_shinfo(skb)->frags[i]; 1039 } 1040 } else if (i < MAX_SKB_FRAGS) { 1041 if (copy > PAGE_SIZE) 1042 copy = PAGE_SIZE; 1043 page = alloc_pages(sk->sk_allocation, 0); 1044 if (page == NULL) { 1045 err = -ENOMEM; 1046 goto error; 1047 } 1048 sk->sk_sndmsg_page = page; 1049 sk->sk_sndmsg_off = 0; 1050 1051 skb_fill_page_desc(skb, i, page, 0, 0); 1052 frag = &skb_shinfo(skb)->frags[i]; 1053 } else { 1054 err = -EMSGSIZE; 1055 goto error; 1056 } 1057 if (getfrag(from, page_address(frag->page)+frag->page_offset+frag->size, offset, copy, skb->len, skb) < 0) { 1058 err = -EFAULT; 1059 goto error; 1060 } 1061 sk->sk_sndmsg_off += copy; 1062 frag->size += copy; 1063 skb->len += copy; 1064 skb->data_len += copy; 1065 skb->truesize += copy; 1066 atomic_add(copy, &sk->sk_wmem_alloc); 1067 } 1068 offset += copy; 1069 length -= copy; 1070 } 1071 1072 return 0; 1073 1074 error: 1075 inet->cork.length -= length; 1076 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS); 1077 return err; 1078 } 1079 1080 ssize_t ip_append_page(struct sock *sk, struct page *page, 1081 int offset, size_t size, int flags) 1082 { 1083 struct inet_sock *inet = inet_sk(sk); 1084 struct sk_buff *skb; 1085 struct rtable *rt; 1086 struct ip_options *opt = NULL; 1087 int hh_len; 1088 int mtu; 1089 int len; 1090 int err; 1091 unsigned int maxfraglen, fragheaderlen, fraggap; 1092 1093 if (inet->hdrincl) 1094 return -EPERM; 1095 1096 if (flags&MSG_PROBE) 1097 return 0; 1098 1099 if (skb_queue_empty(&sk->sk_write_queue)) 1100 return -EINVAL; 1101 1102 rt = (struct rtable *)inet->cork.dst; 1103 if (inet->cork.flags & IPCORK_OPT) 1104 opt = inet->cork.opt; 1105 1106 if (!(rt->u.dst.dev->features&NETIF_F_SG)) 1107 return -EOPNOTSUPP; 1108 1109 hh_len = LL_RESERVED_SPACE(rt->u.dst.dev); 1110 mtu = inet->cork.fragsize; 1111 1112 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0); 1113 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen; 1114 1115 if (inet->cork.length + size > 0xFFFF - fragheaderlen) { 1116 ip_local_error(sk, EMSGSIZE, rt->rt_dst, inet->inet_dport, mtu); 1117 return -EMSGSIZE; 1118 } 1119 1120 if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL) 1121 return -EINVAL; 1122 1123 inet->cork.length += size; 1124 if ((sk->sk_protocol == IPPROTO_UDP) && 1125 (rt->u.dst.dev->features & NETIF_F_UFO)) { 1126 skb_shinfo(skb)->gso_size = mtu - fragheaderlen; 1127 skb_shinfo(skb)->gso_type = SKB_GSO_UDP; 1128 } 1129 1130 1131 while (size > 0) { 1132 int i; 1133 1134 if (skb_is_gso(skb)) 1135 len = size; 1136 else { 1137 1138 /* Check if the remaining data fits into current packet. */ 1139 len = mtu - skb->len; 1140 if (len < size) 1141 len = maxfraglen - skb->len; 1142 } 1143 if (len <= 0) { 1144 struct sk_buff *skb_prev; 1145 int alloclen; 1146 1147 skb_prev = skb; 1148 fraggap = skb_prev->len - maxfraglen; 1149 1150 alloclen = fragheaderlen + hh_len + fraggap + 15; 1151 skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation); 1152 if (unlikely(!skb)) { 1153 err = -ENOBUFS; 1154 goto error; 1155 } 1156 1157 /* 1158 * Fill in the control structures 1159 */ 1160 skb->ip_summed = CHECKSUM_NONE; 1161 skb->csum = 0; 1162 skb_reserve(skb, hh_len); 1163 1164 /* 1165 * Find where to start putting bytes. 1166 */ 1167 skb_put(skb, fragheaderlen + fraggap); 1168 skb_reset_network_header(skb); 1169 skb->transport_header = (skb->network_header + 1170 fragheaderlen); 1171 if (fraggap) { 1172 skb->csum = skb_copy_and_csum_bits(skb_prev, 1173 maxfraglen, 1174 skb_transport_header(skb), 1175 fraggap, 0); 1176 skb_prev->csum = csum_sub(skb_prev->csum, 1177 skb->csum); 1178 pskb_trim_unique(skb_prev, maxfraglen); 1179 } 1180 1181 /* 1182 * Put the packet on the pending queue. 1183 */ 1184 __skb_queue_tail(&sk->sk_write_queue, skb); 1185 continue; 1186 } 1187 1188 i = skb_shinfo(skb)->nr_frags; 1189 if (len > size) 1190 len = size; 1191 if (skb_can_coalesce(skb, i, page, offset)) { 1192 skb_shinfo(skb)->frags[i-1].size += len; 1193 } else if (i < MAX_SKB_FRAGS) { 1194 get_page(page); 1195 skb_fill_page_desc(skb, i, page, offset, len); 1196 } else { 1197 err = -EMSGSIZE; 1198 goto error; 1199 } 1200 1201 if (skb->ip_summed == CHECKSUM_NONE) { 1202 __wsum csum; 1203 csum = csum_page(page, offset, len); 1204 skb->csum = csum_block_add(skb->csum, csum, skb->len); 1205 } 1206 1207 skb->len += len; 1208 skb->data_len += len; 1209 skb->truesize += len; 1210 atomic_add(len, &sk->sk_wmem_alloc); 1211 offset += len; 1212 size -= len; 1213 } 1214 return 0; 1215 1216 error: 1217 inet->cork.length -= size; 1218 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS); 1219 return err; 1220 } 1221 1222 static void ip_cork_release(struct inet_sock *inet) 1223 { 1224 inet->cork.flags &= ~IPCORK_OPT; 1225 kfree(inet->cork.opt); 1226 inet->cork.opt = NULL; 1227 dst_release(inet->cork.dst); 1228 inet->cork.dst = NULL; 1229 } 1230 1231 /* 1232 * Combined all pending IP fragments on the socket as one IP datagram 1233 * and push them out. 1234 */ 1235 int ip_push_pending_frames(struct sock *sk) 1236 { 1237 struct sk_buff *skb, *tmp_skb; 1238 struct sk_buff **tail_skb; 1239 struct inet_sock *inet = inet_sk(sk); 1240 struct net *net = sock_net(sk); 1241 struct ip_options *opt = NULL; 1242 struct rtable *rt = (struct rtable *)inet->cork.dst; 1243 struct iphdr *iph; 1244 __be16 df = 0; 1245 __u8 ttl; 1246 int err = 0; 1247 1248 if ((skb = __skb_dequeue(&sk->sk_write_queue)) == NULL) 1249 goto out; 1250 tail_skb = &(skb_shinfo(skb)->frag_list); 1251 1252 /* move skb->data to ip header from ext header */ 1253 if (skb->data < skb_network_header(skb)) 1254 __skb_pull(skb, skb_network_offset(skb)); 1255 while ((tmp_skb = __skb_dequeue(&sk->sk_write_queue)) != NULL) { 1256 __skb_pull(tmp_skb, skb_network_header_len(skb)); 1257 *tail_skb = tmp_skb; 1258 tail_skb = &(tmp_skb->next); 1259 skb->len += tmp_skb->len; 1260 skb->data_len += tmp_skb->len; 1261 skb->truesize += tmp_skb->truesize; 1262 tmp_skb->destructor = NULL; 1263 tmp_skb->sk = NULL; 1264 } 1265 1266 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow 1267 * to fragment the frame generated here. No matter, what transforms 1268 * how transforms change size of the packet, it will come out. 1269 */ 1270 if (inet->pmtudisc < IP_PMTUDISC_DO) 1271 skb->local_df = 1; 1272 1273 /* DF bit is set when we want to see DF on outgoing frames. 1274 * If local_df is set too, we still allow to fragment this frame 1275 * locally. */ 1276 if (inet->pmtudisc >= IP_PMTUDISC_DO || 1277 (skb->len <= dst_mtu(&rt->u.dst) && 1278 ip_dont_fragment(sk, &rt->u.dst))) 1279 df = htons(IP_DF); 1280 1281 if (inet->cork.flags & IPCORK_OPT) 1282 opt = inet->cork.opt; 1283 1284 if (rt->rt_type == RTN_MULTICAST) 1285 ttl = inet->mc_ttl; 1286 else 1287 ttl = ip_select_ttl(inet, &rt->u.dst); 1288 1289 iph = (struct iphdr *)skb->data; 1290 iph->version = 4; 1291 iph->ihl = 5; 1292 if (opt) { 1293 iph->ihl += opt->optlen>>2; 1294 ip_options_build(skb, opt, inet->cork.addr, rt, 0); 1295 } 1296 iph->tos = inet->tos; 1297 iph->frag_off = df; 1298 ip_select_ident(iph, &rt->u.dst, sk); 1299 iph->ttl = ttl; 1300 iph->protocol = sk->sk_protocol; 1301 iph->saddr = rt->rt_src; 1302 iph->daddr = rt->rt_dst; 1303 1304 skb->priority = sk->sk_priority; 1305 skb->mark = sk->sk_mark; 1306 /* 1307 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec 1308 * on dst refcount 1309 */ 1310 inet->cork.dst = NULL; 1311 skb_dst_set(skb, &rt->u.dst); 1312 1313 if (iph->protocol == IPPROTO_ICMP) 1314 icmp_out_count(net, ((struct icmphdr *) 1315 skb_transport_header(skb))->type); 1316 1317 /* Netfilter gets whole the not fragmented skb. */ 1318 err = ip_local_out(skb); 1319 if (err) { 1320 if (err > 0) 1321 err = net_xmit_errno(err); 1322 if (err) 1323 goto error; 1324 } 1325 1326 out: 1327 ip_cork_release(inet); 1328 return err; 1329 1330 error: 1331 IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS); 1332 goto out; 1333 } 1334 1335 /* 1336 * Throw away all pending data on the socket. 1337 */ 1338 void ip_flush_pending_frames(struct sock *sk) 1339 { 1340 struct sk_buff *skb; 1341 1342 while ((skb = __skb_dequeue_tail(&sk->sk_write_queue)) != NULL) 1343 kfree_skb(skb); 1344 1345 ip_cork_release(inet_sk(sk)); 1346 } 1347 1348 1349 /* 1350 * Fetch data from kernel space and fill in checksum if needed. 1351 */ 1352 static int ip_reply_glue_bits(void *dptr, char *to, int offset, 1353 int len, int odd, struct sk_buff *skb) 1354 { 1355 __wsum csum; 1356 1357 csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0); 1358 skb->csum = csum_block_add(skb->csum, csum, odd); 1359 return 0; 1360 } 1361 1362 /* 1363 * Generic function to send a packet as reply to another packet. 1364 * Used to send TCP resets so far. ICMP should use this function too. 1365 * 1366 * Should run single threaded per socket because it uses the sock 1367 * structure to pass arguments. 1368 */ 1369 void ip_send_reply(struct sock *sk, struct sk_buff *skb, struct ip_reply_arg *arg, 1370 unsigned int len) 1371 { 1372 struct inet_sock *inet = inet_sk(sk); 1373 struct { 1374 struct ip_options opt; 1375 char data[40]; 1376 } replyopts; 1377 struct ipcm_cookie ipc; 1378 __be32 daddr; 1379 struct rtable *rt = skb_rtable(skb); 1380 1381 if (ip_options_echo(&replyopts.opt, skb)) 1382 return; 1383 1384 daddr = ipc.addr = rt->rt_src; 1385 ipc.opt = NULL; 1386 ipc.shtx.flags = 0; 1387 1388 if (replyopts.opt.optlen) { 1389 ipc.opt = &replyopts.opt; 1390 1391 if (ipc.opt->srr) 1392 daddr = replyopts.opt.faddr; 1393 } 1394 1395 { 1396 struct flowi fl = { .oif = arg->bound_dev_if, 1397 .nl_u = { .ip4_u = 1398 { .daddr = daddr, 1399 .saddr = rt->rt_spec_dst, 1400 .tos = RT_TOS(ip_hdr(skb)->tos) } }, 1401 /* Not quite clean, but right. */ 1402 .uli_u = { .ports = 1403 { .sport = tcp_hdr(skb)->dest, 1404 .dport = tcp_hdr(skb)->source } }, 1405 .proto = sk->sk_protocol, 1406 .flags = ip_reply_arg_flowi_flags(arg) }; 1407 security_skb_classify_flow(skb, &fl); 1408 if (ip_route_output_key(sock_net(sk), &rt, &fl)) 1409 return; 1410 } 1411 1412 /* And let IP do all the hard work. 1413 1414 This chunk is not reenterable, hence spinlock. 1415 Note that it uses the fact, that this function is called 1416 with locally disabled BH and that sk cannot be already spinlocked. 1417 */ 1418 bh_lock_sock(sk); 1419 inet->tos = ip_hdr(skb)->tos; 1420 sk->sk_priority = skb->priority; 1421 sk->sk_protocol = ip_hdr(skb)->protocol; 1422 sk->sk_bound_dev_if = arg->bound_dev_if; 1423 ip_append_data(sk, ip_reply_glue_bits, arg->iov->iov_base, len, 0, 1424 &ipc, &rt, MSG_DONTWAIT); 1425 if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) { 1426 if (arg->csumoffset >= 0) 1427 *((__sum16 *)skb_transport_header(skb) + 1428 arg->csumoffset) = csum_fold(csum_add(skb->csum, 1429 arg->csum)); 1430 skb->ip_summed = CHECKSUM_NONE; 1431 ip_push_pending_frames(sk); 1432 } 1433 1434 bh_unlock_sock(sk); 1435 1436 ip_rt_put(rt); 1437 } 1438 1439 void __init ip_init(void) 1440 { 1441 ip_rt_init(); 1442 inet_initpeers(); 1443 1444 #if defined(CONFIG_IP_MULTICAST) && defined(CONFIG_PROC_FS) 1445 igmp_mc_proc_init(); 1446 #endif 1447 } 1448 1449 EXPORT_SYMBOL(ip_generic_getfrag); 1450 EXPORT_SYMBOL(ip_queue_xmit); 1451 EXPORT_SYMBOL(ip_send_check); 1452