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 skb = skb_peek_tail(&sk->sk_write_queue); 877 878 inet->cork.length += length; 879 if (((length > mtu) || (skb && skb_is_gso(skb))) && 880 (sk->sk_protocol == IPPROTO_UDP) && 881 (rt->u.dst.dev->features & NETIF_F_UFO)) { 882 err = ip_ufo_append_data(sk, getfrag, from, length, hh_len, 883 fragheaderlen, transhdrlen, mtu, 884 flags); 885 if (err) 886 goto error; 887 return 0; 888 } 889 890 /* So, what's going on in the loop below? 891 * 892 * We use calculated fragment length to generate chained skb, 893 * each of segments is IP fragment ready for sending to network after 894 * adding appropriate IP header. 895 */ 896 897 if (!skb) 898 goto alloc_new_skb; 899 900 while (length > 0) { 901 /* Check if the remaining data fits into current packet. */ 902 copy = mtu - skb->len; 903 if (copy < length) 904 copy = maxfraglen - skb->len; 905 if (copy <= 0) { 906 char *data; 907 unsigned int datalen; 908 unsigned int fraglen; 909 unsigned int fraggap; 910 unsigned int alloclen; 911 struct sk_buff *skb_prev; 912 alloc_new_skb: 913 skb_prev = skb; 914 if (skb_prev) 915 fraggap = skb_prev->len - maxfraglen; 916 else 917 fraggap = 0; 918 919 /* 920 * If remaining data exceeds the mtu, 921 * we know we need more fragment(s). 922 */ 923 datalen = length + fraggap; 924 if (datalen > mtu - fragheaderlen) 925 datalen = maxfraglen - fragheaderlen; 926 fraglen = datalen + fragheaderlen; 927 928 if ((flags & MSG_MORE) && 929 !(rt->u.dst.dev->features&NETIF_F_SG)) 930 alloclen = mtu; 931 else 932 alloclen = datalen + fragheaderlen; 933 934 /* The last fragment gets additional space at tail. 935 * Note, with MSG_MORE we overallocate on fragments, 936 * because we have no idea what fragment will be 937 * the last. 938 */ 939 if (datalen == length + fraggap) 940 alloclen += rt->u.dst.trailer_len; 941 942 if (transhdrlen) { 943 skb = sock_alloc_send_skb(sk, 944 alloclen + hh_len + 15, 945 (flags & MSG_DONTWAIT), &err); 946 } else { 947 skb = NULL; 948 if (atomic_read(&sk->sk_wmem_alloc) <= 949 2 * sk->sk_sndbuf) 950 skb = sock_wmalloc(sk, 951 alloclen + hh_len + 15, 1, 952 sk->sk_allocation); 953 if (unlikely(skb == NULL)) 954 err = -ENOBUFS; 955 else 956 /* only the initial fragment is 957 time stamped */ 958 ipc->shtx.flags = 0; 959 } 960 if (skb == NULL) 961 goto error; 962 963 /* 964 * Fill in the control structures 965 */ 966 skb->ip_summed = csummode; 967 skb->csum = 0; 968 skb_reserve(skb, hh_len); 969 *skb_tx(skb) = ipc->shtx; 970 971 /* 972 * Find where to start putting bytes. 973 */ 974 data = skb_put(skb, fraglen); 975 skb_set_network_header(skb, exthdrlen); 976 skb->transport_header = (skb->network_header + 977 fragheaderlen); 978 data += fragheaderlen; 979 980 if (fraggap) { 981 skb->csum = skb_copy_and_csum_bits( 982 skb_prev, maxfraglen, 983 data + transhdrlen, fraggap, 0); 984 skb_prev->csum = csum_sub(skb_prev->csum, 985 skb->csum); 986 data += fraggap; 987 pskb_trim_unique(skb_prev, maxfraglen); 988 } 989 990 copy = datalen - transhdrlen - fraggap; 991 if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) { 992 err = -EFAULT; 993 kfree_skb(skb); 994 goto error; 995 } 996 997 offset += copy; 998 length -= datalen - fraggap; 999 transhdrlen = 0; 1000 exthdrlen = 0; 1001 csummode = CHECKSUM_NONE; 1002 1003 /* 1004 * Put the packet on the pending queue. 1005 */ 1006 __skb_queue_tail(&sk->sk_write_queue, skb); 1007 continue; 1008 } 1009 1010 if (copy > length) 1011 copy = length; 1012 1013 if (!(rt->u.dst.dev->features&NETIF_F_SG)) { 1014 unsigned int off; 1015 1016 off = skb->len; 1017 if (getfrag(from, skb_put(skb, copy), 1018 offset, copy, off, skb) < 0) { 1019 __skb_trim(skb, off); 1020 err = -EFAULT; 1021 goto error; 1022 } 1023 } else { 1024 int i = skb_shinfo(skb)->nr_frags; 1025 skb_frag_t *frag = &skb_shinfo(skb)->frags[i-1]; 1026 struct page *page = sk->sk_sndmsg_page; 1027 int off = sk->sk_sndmsg_off; 1028 unsigned int left; 1029 1030 if (page && (left = PAGE_SIZE - off) > 0) { 1031 if (copy >= left) 1032 copy = left; 1033 if (page != frag->page) { 1034 if (i == MAX_SKB_FRAGS) { 1035 err = -EMSGSIZE; 1036 goto error; 1037 } 1038 get_page(page); 1039 skb_fill_page_desc(skb, i, page, sk->sk_sndmsg_off, 0); 1040 frag = &skb_shinfo(skb)->frags[i]; 1041 } 1042 } else if (i < MAX_SKB_FRAGS) { 1043 if (copy > PAGE_SIZE) 1044 copy = PAGE_SIZE; 1045 page = alloc_pages(sk->sk_allocation, 0); 1046 if (page == NULL) { 1047 err = -ENOMEM; 1048 goto error; 1049 } 1050 sk->sk_sndmsg_page = page; 1051 sk->sk_sndmsg_off = 0; 1052 1053 skb_fill_page_desc(skb, i, page, 0, 0); 1054 frag = &skb_shinfo(skb)->frags[i]; 1055 } else { 1056 err = -EMSGSIZE; 1057 goto error; 1058 } 1059 if (getfrag(from, page_address(frag->page)+frag->page_offset+frag->size, offset, copy, skb->len, skb) < 0) { 1060 err = -EFAULT; 1061 goto error; 1062 } 1063 sk->sk_sndmsg_off += copy; 1064 frag->size += copy; 1065 skb->len += copy; 1066 skb->data_len += copy; 1067 skb->truesize += copy; 1068 atomic_add(copy, &sk->sk_wmem_alloc); 1069 } 1070 offset += copy; 1071 length -= copy; 1072 } 1073 1074 return 0; 1075 1076 error: 1077 inet->cork.length -= length; 1078 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS); 1079 return err; 1080 } 1081 1082 ssize_t ip_append_page(struct sock *sk, struct page *page, 1083 int offset, size_t size, int flags) 1084 { 1085 struct inet_sock *inet = inet_sk(sk); 1086 struct sk_buff *skb; 1087 struct rtable *rt; 1088 struct ip_options *opt = NULL; 1089 int hh_len; 1090 int mtu; 1091 int len; 1092 int err; 1093 unsigned int maxfraglen, fragheaderlen, fraggap; 1094 1095 if (inet->hdrincl) 1096 return -EPERM; 1097 1098 if (flags&MSG_PROBE) 1099 return 0; 1100 1101 if (skb_queue_empty(&sk->sk_write_queue)) 1102 return -EINVAL; 1103 1104 rt = (struct rtable *)inet->cork.dst; 1105 if (inet->cork.flags & IPCORK_OPT) 1106 opt = inet->cork.opt; 1107 1108 if (!(rt->u.dst.dev->features&NETIF_F_SG)) 1109 return -EOPNOTSUPP; 1110 1111 hh_len = LL_RESERVED_SPACE(rt->u.dst.dev); 1112 mtu = inet->cork.fragsize; 1113 1114 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0); 1115 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen; 1116 1117 if (inet->cork.length + size > 0xFFFF - fragheaderlen) { 1118 ip_local_error(sk, EMSGSIZE, rt->rt_dst, inet->inet_dport, mtu); 1119 return -EMSGSIZE; 1120 } 1121 1122 if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL) 1123 return -EINVAL; 1124 1125 inet->cork.length += size; 1126 if ((size + skb->len > mtu) && 1127 (sk->sk_protocol == IPPROTO_UDP) && 1128 (rt->u.dst.dev->features & NETIF_F_UFO)) { 1129 skb_shinfo(skb)->gso_size = mtu - fragheaderlen; 1130 skb_shinfo(skb)->gso_type = SKB_GSO_UDP; 1131 } 1132 1133 1134 while (size > 0) { 1135 int i; 1136 1137 if (skb_is_gso(skb)) 1138 len = size; 1139 else { 1140 1141 /* Check if the remaining data fits into current packet. */ 1142 len = mtu - skb->len; 1143 if (len < size) 1144 len = maxfraglen - skb->len; 1145 } 1146 if (len <= 0) { 1147 struct sk_buff *skb_prev; 1148 int alloclen; 1149 1150 skb_prev = skb; 1151 fraggap = skb_prev->len - maxfraglen; 1152 1153 alloclen = fragheaderlen + hh_len + fraggap + 15; 1154 skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation); 1155 if (unlikely(!skb)) { 1156 err = -ENOBUFS; 1157 goto error; 1158 } 1159 1160 /* 1161 * Fill in the control structures 1162 */ 1163 skb->ip_summed = CHECKSUM_NONE; 1164 skb->csum = 0; 1165 skb_reserve(skb, hh_len); 1166 1167 /* 1168 * Find where to start putting bytes. 1169 */ 1170 skb_put(skb, fragheaderlen + fraggap); 1171 skb_reset_network_header(skb); 1172 skb->transport_header = (skb->network_header + 1173 fragheaderlen); 1174 if (fraggap) { 1175 skb->csum = skb_copy_and_csum_bits(skb_prev, 1176 maxfraglen, 1177 skb_transport_header(skb), 1178 fraggap, 0); 1179 skb_prev->csum = csum_sub(skb_prev->csum, 1180 skb->csum); 1181 pskb_trim_unique(skb_prev, maxfraglen); 1182 } 1183 1184 /* 1185 * Put the packet on the pending queue. 1186 */ 1187 __skb_queue_tail(&sk->sk_write_queue, skb); 1188 continue; 1189 } 1190 1191 i = skb_shinfo(skb)->nr_frags; 1192 if (len > size) 1193 len = size; 1194 if (skb_can_coalesce(skb, i, page, offset)) { 1195 skb_shinfo(skb)->frags[i-1].size += len; 1196 } else if (i < MAX_SKB_FRAGS) { 1197 get_page(page); 1198 skb_fill_page_desc(skb, i, page, offset, len); 1199 } else { 1200 err = -EMSGSIZE; 1201 goto error; 1202 } 1203 1204 if (skb->ip_summed == CHECKSUM_NONE) { 1205 __wsum csum; 1206 csum = csum_page(page, offset, len); 1207 skb->csum = csum_block_add(skb->csum, csum, skb->len); 1208 } 1209 1210 skb->len += len; 1211 skb->data_len += len; 1212 skb->truesize += len; 1213 atomic_add(len, &sk->sk_wmem_alloc); 1214 offset += len; 1215 size -= len; 1216 } 1217 return 0; 1218 1219 error: 1220 inet->cork.length -= size; 1221 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS); 1222 return err; 1223 } 1224 1225 static void ip_cork_release(struct inet_sock *inet) 1226 { 1227 inet->cork.flags &= ~IPCORK_OPT; 1228 kfree(inet->cork.opt); 1229 inet->cork.opt = NULL; 1230 dst_release(inet->cork.dst); 1231 inet->cork.dst = NULL; 1232 } 1233 1234 /* 1235 * Combined all pending IP fragments on the socket as one IP datagram 1236 * and push them out. 1237 */ 1238 int ip_push_pending_frames(struct sock *sk) 1239 { 1240 struct sk_buff *skb, *tmp_skb; 1241 struct sk_buff **tail_skb; 1242 struct inet_sock *inet = inet_sk(sk); 1243 struct net *net = sock_net(sk); 1244 struct ip_options *opt = NULL; 1245 struct rtable *rt = (struct rtable *)inet->cork.dst; 1246 struct iphdr *iph; 1247 __be16 df = 0; 1248 __u8 ttl; 1249 int err = 0; 1250 1251 if ((skb = __skb_dequeue(&sk->sk_write_queue)) == NULL) 1252 goto out; 1253 tail_skb = &(skb_shinfo(skb)->frag_list); 1254 1255 /* move skb->data to ip header from ext header */ 1256 if (skb->data < skb_network_header(skb)) 1257 __skb_pull(skb, skb_network_offset(skb)); 1258 while ((tmp_skb = __skb_dequeue(&sk->sk_write_queue)) != NULL) { 1259 __skb_pull(tmp_skb, skb_network_header_len(skb)); 1260 *tail_skb = tmp_skb; 1261 tail_skb = &(tmp_skb->next); 1262 skb->len += tmp_skb->len; 1263 skb->data_len += tmp_skb->len; 1264 skb->truesize += tmp_skb->truesize; 1265 tmp_skb->destructor = NULL; 1266 tmp_skb->sk = NULL; 1267 } 1268 1269 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow 1270 * to fragment the frame generated here. No matter, what transforms 1271 * how transforms change size of the packet, it will come out. 1272 */ 1273 if (inet->pmtudisc < IP_PMTUDISC_DO) 1274 skb->local_df = 1; 1275 1276 /* DF bit is set when we want to see DF on outgoing frames. 1277 * If local_df is set too, we still allow to fragment this frame 1278 * locally. */ 1279 if (inet->pmtudisc >= IP_PMTUDISC_DO || 1280 (skb->len <= dst_mtu(&rt->u.dst) && 1281 ip_dont_fragment(sk, &rt->u.dst))) 1282 df = htons(IP_DF); 1283 1284 if (inet->cork.flags & IPCORK_OPT) 1285 opt = inet->cork.opt; 1286 1287 if (rt->rt_type == RTN_MULTICAST) 1288 ttl = inet->mc_ttl; 1289 else 1290 ttl = ip_select_ttl(inet, &rt->u.dst); 1291 1292 iph = (struct iphdr *)skb->data; 1293 iph->version = 4; 1294 iph->ihl = 5; 1295 if (opt) { 1296 iph->ihl += opt->optlen>>2; 1297 ip_options_build(skb, opt, inet->cork.addr, rt, 0); 1298 } 1299 iph->tos = inet->tos; 1300 iph->frag_off = df; 1301 ip_select_ident(iph, &rt->u.dst, sk); 1302 iph->ttl = ttl; 1303 iph->protocol = sk->sk_protocol; 1304 iph->saddr = rt->rt_src; 1305 iph->daddr = rt->rt_dst; 1306 1307 skb->priority = sk->sk_priority; 1308 skb->mark = sk->sk_mark; 1309 /* 1310 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec 1311 * on dst refcount 1312 */ 1313 inet->cork.dst = NULL; 1314 skb_dst_set(skb, &rt->u.dst); 1315 1316 if (iph->protocol == IPPROTO_ICMP) 1317 icmp_out_count(net, ((struct icmphdr *) 1318 skb_transport_header(skb))->type); 1319 1320 /* Netfilter gets whole the not fragmented skb. */ 1321 err = ip_local_out(skb); 1322 if (err) { 1323 if (err > 0) 1324 err = net_xmit_errno(err); 1325 if (err) 1326 goto error; 1327 } 1328 1329 out: 1330 ip_cork_release(inet); 1331 return err; 1332 1333 error: 1334 IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS); 1335 goto out; 1336 } 1337 1338 /* 1339 * Throw away all pending data on the socket. 1340 */ 1341 void ip_flush_pending_frames(struct sock *sk) 1342 { 1343 struct sk_buff *skb; 1344 1345 while ((skb = __skb_dequeue_tail(&sk->sk_write_queue)) != NULL) 1346 kfree_skb(skb); 1347 1348 ip_cork_release(inet_sk(sk)); 1349 } 1350 1351 1352 /* 1353 * Fetch data from kernel space and fill in checksum if needed. 1354 */ 1355 static int ip_reply_glue_bits(void *dptr, char *to, int offset, 1356 int len, int odd, struct sk_buff *skb) 1357 { 1358 __wsum csum; 1359 1360 csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0); 1361 skb->csum = csum_block_add(skb->csum, csum, odd); 1362 return 0; 1363 } 1364 1365 /* 1366 * Generic function to send a packet as reply to another packet. 1367 * Used to send TCP resets so far. ICMP should use this function too. 1368 * 1369 * Should run single threaded per socket because it uses the sock 1370 * structure to pass arguments. 1371 */ 1372 void ip_send_reply(struct sock *sk, struct sk_buff *skb, struct ip_reply_arg *arg, 1373 unsigned int len) 1374 { 1375 struct inet_sock *inet = inet_sk(sk); 1376 struct { 1377 struct ip_options opt; 1378 char data[40]; 1379 } replyopts; 1380 struct ipcm_cookie ipc; 1381 __be32 daddr; 1382 struct rtable *rt = skb_rtable(skb); 1383 1384 if (ip_options_echo(&replyopts.opt, skb)) 1385 return; 1386 1387 daddr = ipc.addr = rt->rt_src; 1388 ipc.opt = NULL; 1389 ipc.shtx.flags = 0; 1390 1391 if (replyopts.opt.optlen) { 1392 ipc.opt = &replyopts.opt; 1393 1394 if (ipc.opt->srr) 1395 daddr = replyopts.opt.faddr; 1396 } 1397 1398 { 1399 struct flowi fl = { .oif = arg->bound_dev_if, 1400 .nl_u = { .ip4_u = 1401 { .daddr = daddr, 1402 .saddr = rt->rt_spec_dst, 1403 .tos = RT_TOS(ip_hdr(skb)->tos) } }, 1404 /* Not quite clean, but right. */ 1405 .uli_u = { .ports = 1406 { .sport = tcp_hdr(skb)->dest, 1407 .dport = tcp_hdr(skb)->source } }, 1408 .proto = sk->sk_protocol, 1409 .flags = ip_reply_arg_flowi_flags(arg) }; 1410 security_skb_classify_flow(skb, &fl); 1411 if (ip_route_output_key(sock_net(sk), &rt, &fl)) 1412 return; 1413 } 1414 1415 /* And let IP do all the hard work. 1416 1417 This chunk is not reenterable, hence spinlock. 1418 Note that it uses the fact, that this function is called 1419 with locally disabled BH and that sk cannot be already spinlocked. 1420 */ 1421 bh_lock_sock(sk); 1422 inet->tos = ip_hdr(skb)->tos; 1423 sk->sk_priority = skb->priority; 1424 sk->sk_protocol = ip_hdr(skb)->protocol; 1425 sk->sk_bound_dev_if = arg->bound_dev_if; 1426 ip_append_data(sk, ip_reply_glue_bits, arg->iov->iov_base, len, 0, 1427 &ipc, &rt, MSG_DONTWAIT); 1428 if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) { 1429 if (arg->csumoffset >= 0) 1430 *((__sum16 *)skb_transport_header(skb) + 1431 arg->csumoffset) = csum_fold(csum_add(skb->csum, 1432 arg->csum)); 1433 skb->ip_summed = CHECKSUM_NONE; 1434 ip_push_pending_frames(sk); 1435 } 1436 1437 bh_unlock_sock(sk); 1438 1439 ip_rt_put(rt); 1440 } 1441 1442 void __init ip_init(void) 1443 { 1444 ip_rt_init(); 1445 inet_initpeers(); 1446 1447 #if defined(CONFIG_IP_MULTICAST) && defined(CONFIG_PROC_FS) 1448 igmp_mc_proc_init(); 1449 #endif 1450 } 1451 1452 EXPORT_SYMBOL(ip_generic_getfrag); 1453 EXPORT_SYMBOL(ip_queue_xmit); 1454 EXPORT_SYMBOL(ip_send_check); 1455