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 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 85 /* Generate a checksum for an outgoing IP datagram. */ 86 __inline__ void ip_send_check(struct iphdr *iph) 87 { 88 iph->check = 0; 89 iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl); 90 } 91 92 int __ip_local_out(struct sk_buff *skb) 93 { 94 struct iphdr *iph = ip_hdr(skb); 95 96 iph->tot_len = htons(skb->len); 97 ip_send_check(iph); 98 return nf_hook(PF_INET, NF_INET_LOCAL_OUT, skb, NULL, skb_dst(skb)->dev, 99 dst_output); 100 } 101 102 int ip_local_out(struct sk_buff *skb) 103 { 104 int err; 105 106 err = __ip_local_out(skb); 107 if (likely(err == 1)) 108 err = dst_output(skb); 109 110 return err; 111 } 112 EXPORT_SYMBOL_GPL(ip_local_out); 113 114 /* dev_loopback_xmit for use with netfilter. */ 115 static int ip_dev_loopback_xmit(struct sk_buff *newskb) 116 { 117 skb_reset_mac_header(newskb); 118 __skb_pull(newskb, skb_network_offset(newskb)); 119 newskb->pkt_type = PACKET_LOOPBACK; 120 newskb->ip_summed = CHECKSUM_UNNECESSARY; 121 WARN_ON(!skb_dst(newskb)); 122 netif_rx(newskb); 123 return 0; 124 } 125 126 static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst) 127 { 128 int ttl = inet->uc_ttl; 129 130 if (ttl < 0) 131 ttl = dst_metric(dst, RTAX_HOPLIMIT); 132 return ttl; 133 } 134 135 /* 136 * Add an ip header to a skbuff and send it out. 137 * 138 */ 139 int ip_build_and_send_pkt(struct sk_buff *skb, struct sock *sk, 140 __be32 saddr, __be32 daddr, struct ip_options *opt) 141 { 142 struct inet_sock *inet = inet_sk(sk); 143 struct rtable *rt = skb_rtable(skb); 144 struct iphdr *iph; 145 146 /* Build the IP header. */ 147 skb_push(skb, sizeof(struct iphdr) + (opt ? opt->optlen : 0)); 148 skb_reset_network_header(skb); 149 iph = ip_hdr(skb); 150 iph->version = 4; 151 iph->ihl = 5; 152 iph->tos = inet->tos; 153 if (ip_dont_fragment(sk, &rt->u.dst)) 154 iph->frag_off = htons(IP_DF); 155 else 156 iph->frag_off = 0; 157 iph->ttl = ip_select_ttl(inet, &rt->u.dst); 158 iph->daddr = rt->rt_dst; 159 iph->saddr = rt->rt_src; 160 iph->protocol = sk->sk_protocol; 161 ip_select_ident(iph, &rt->u.dst, sk); 162 163 if (opt && opt->optlen) { 164 iph->ihl += opt->optlen>>2; 165 ip_options_build(skb, opt, daddr, rt, 0); 166 } 167 168 skb->priority = sk->sk_priority; 169 skb->mark = sk->sk_mark; 170 171 /* Send it out. */ 172 return ip_local_out(skb); 173 } 174 175 EXPORT_SYMBOL_GPL(ip_build_and_send_pkt); 176 177 static inline int ip_finish_output2(struct sk_buff *skb) 178 { 179 struct dst_entry *dst = skb_dst(skb); 180 struct rtable *rt = (struct rtable *)dst; 181 struct net_device *dev = dst->dev; 182 unsigned int hh_len = LL_RESERVED_SPACE(dev); 183 184 if (rt->rt_type == RTN_MULTICAST) { 185 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUTMCAST, skb->len); 186 } else if (rt->rt_type == RTN_BROADCAST) 187 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUTBCAST, skb->len); 188 189 /* Be paranoid, rather than too clever. */ 190 if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) { 191 struct sk_buff *skb2; 192 193 skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev)); 194 if (skb2 == NULL) { 195 kfree_skb(skb); 196 return -ENOMEM; 197 } 198 if (skb->sk) 199 skb_set_owner_w(skb2, skb->sk); 200 kfree_skb(skb); 201 skb = skb2; 202 } 203 204 if (dst->hh) 205 return neigh_hh_output(dst->hh, skb); 206 else if (dst->neighbour) 207 return dst->neighbour->output(skb); 208 209 if (net_ratelimit()) 210 printk(KERN_DEBUG "ip_finish_output2: No header cache and no neighbour!\n"); 211 kfree_skb(skb); 212 return -EINVAL; 213 } 214 215 static inline int ip_skb_dst_mtu(struct sk_buff *skb) 216 { 217 struct inet_sock *inet = skb->sk ? inet_sk(skb->sk) : NULL; 218 219 return (inet && inet->pmtudisc == IP_PMTUDISC_PROBE) ? 220 skb_dst(skb)->dev->mtu : dst_mtu(skb_dst(skb)); 221 } 222 223 static int ip_finish_output(struct sk_buff *skb) 224 { 225 #if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM) 226 /* Policy lookup after SNAT yielded a new policy */ 227 if (skb_dst(skb)->xfrm != NULL) { 228 IPCB(skb)->flags |= IPSKB_REROUTED; 229 return dst_output(skb); 230 } 231 #endif 232 if (skb->len > ip_skb_dst_mtu(skb) && !skb_is_gso(skb)) 233 return ip_fragment(skb, ip_finish_output2); 234 else 235 return ip_finish_output2(skb); 236 } 237 238 int ip_mc_output(struct sk_buff *skb) 239 { 240 struct sock *sk = skb->sk; 241 struct rtable *rt = skb_rtable(skb); 242 struct net_device *dev = rt->u.dst.dev; 243 244 /* 245 * If the indicated interface is up and running, send the packet. 246 */ 247 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len); 248 249 skb->dev = dev; 250 skb->protocol = htons(ETH_P_IP); 251 252 /* 253 * Multicasts are looped back for other local users 254 */ 255 256 if (rt->rt_flags&RTCF_MULTICAST) { 257 if ((!sk || inet_sk(sk)->mc_loop) 258 #ifdef CONFIG_IP_MROUTE 259 /* Small optimization: do not loopback not local frames, 260 which returned after forwarding; they will be dropped 261 by ip_mr_input in any case. 262 Note, that local frames are looped back to be delivered 263 to local recipients. 264 265 This check is duplicated in ip_mr_input at the moment. 266 */ 267 && ((rt->rt_flags&RTCF_LOCAL) || !(IPCB(skb)->flags&IPSKB_FORWARDED)) 268 #endif 269 ) { 270 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC); 271 if (newskb) 272 NF_HOOK(PF_INET, NF_INET_POST_ROUTING, newskb, 273 NULL, newskb->dev, 274 ip_dev_loopback_xmit); 275 } 276 277 /* Multicasts with ttl 0 must not go beyond the host */ 278 279 if (ip_hdr(skb)->ttl == 0) { 280 kfree_skb(skb); 281 return 0; 282 } 283 } 284 285 if (rt->rt_flags&RTCF_BROADCAST) { 286 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC); 287 if (newskb) 288 NF_HOOK(PF_INET, NF_INET_POST_ROUTING, newskb, NULL, 289 newskb->dev, ip_dev_loopback_xmit); 290 } 291 292 return NF_HOOK_COND(PF_INET, NF_INET_POST_ROUTING, skb, NULL, skb->dev, 293 ip_finish_output, 294 !(IPCB(skb)->flags & IPSKB_REROUTED)); 295 } 296 297 int ip_output(struct sk_buff *skb) 298 { 299 struct net_device *dev = skb_dst(skb)->dev; 300 301 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len); 302 303 skb->dev = dev; 304 skb->protocol = htons(ETH_P_IP); 305 306 return NF_HOOK_COND(PF_INET, NF_INET_POST_ROUTING, skb, NULL, dev, 307 ip_finish_output, 308 !(IPCB(skb)->flags & IPSKB_REROUTED)); 309 } 310 311 int ip_queue_xmit(struct sk_buff *skb, int ipfragok) 312 { 313 struct sock *sk = skb->sk; 314 struct inet_sock *inet = inet_sk(sk); 315 struct ip_options *opt = inet->opt; 316 struct rtable *rt; 317 struct iphdr *iph; 318 319 /* Skip all of this if the packet is already routed, 320 * f.e. by something like SCTP. 321 */ 322 rt = skb_rtable(skb); 323 if (rt != NULL) 324 goto packet_routed; 325 326 /* Make sure we can route this packet. */ 327 rt = (struct rtable *)__sk_dst_check(sk, 0); 328 if (rt == NULL) { 329 __be32 daddr; 330 331 /* Use correct destination address if we have options. */ 332 daddr = inet->daddr; 333 if(opt && opt->srr) 334 daddr = opt->faddr; 335 336 { 337 struct flowi fl = { .oif = sk->sk_bound_dev_if, 338 .mark = sk->sk_mark, 339 .nl_u = { .ip4_u = 340 { .daddr = daddr, 341 .saddr = inet->saddr, 342 .tos = RT_CONN_FLAGS(sk) } }, 343 .proto = sk->sk_protocol, 344 .flags = inet_sk_flowi_flags(sk), 345 .uli_u = { .ports = 346 { .sport = inet->sport, 347 .dport = inet->dport } } }; 348 349 /* If this fails, retransmit mechanism of transport layer will 350 * keep trying until route appears or the connection times 351 * itself out. 352 */ 353 security_sk_classify_flow(sk, &fl); 354 if (ip_route_output_flow(sock_net(sk), &rt, &fl, sk, 0)) 355 goto no_route; 356 } 357 sk_setup_caps(sk, &rt->u.dst); 358 } 359 skb_dst_set(skb, dst_clone(&rt->u.dst)); 360 361 packet_routed: 362 if (opt && opt->is_strictroute && rt->rt_dst != rt->rt_gateway) 363 goto no_route; 364 365 /* OK, we know where to send it, allocate and build IP header. */ 366 skb_push(skb, sizeof(struct iphdr) + (opt ? opt->optlen : 0)); 367 skb_reset_network_header(skb); 368 iph = ip_hdr(skb); 369 *((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (inet->tos & 0xff)); 370 if (ip_dont_fragment(sk, &rt->u.dst) && !ipfragok) 371 iph->frag_off = htons(IP_DF); 372 else 373 iph->frag_off = 0; 374 iph->ttl = ip_select_ttl(inet, &rt->u.dst); 375 iph->protocol = sk->sk_protocol; 376 iph->saddr = rt->rt_src; 377 iph->daddr = rt->rt_dst; 378 /* Transport layer set skb->h.foo itself. */ 379 380 if (opt && opt->optlen) { 381 iph->ihl += opt->optlen >> 2; 382 ip_options_build(skb, opt, inet->daddr, rt, 0); 383 } 384 385 ip_select_ident_more(iph, &rt->u.dst, sk, 386 (skb_shinfo(skb)->gso_segs ?: 1) - 1); 387 388 skb->priority = sk->sk_priority; 389 skb->mark = sk->sk_mark; 390 391 return ip_local_out(skb); 392 393 no_route: 394 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES); 395 kfree_skb(skb); 396 return -EHOSTUNREACH; 397 } 398 399 400 static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from) 401 { 402 to->pkt_type = from->pkt_type; 403 to->priority = from->priority; 404 to->protocol = from->protocol; 405 skb_dst_drop(to); 406 skb_dst_set(to, dst_clone(skb_dst(from))); 407 to->dev = from->dev; 408 to->mark = from->mark; 409 410 /* Copy the flags to each fragment. */ 411 IPCB(to)->flags = IPCB(from)->flags; 412 413 #ifdef CONFIG_NET_SCHED 414 to->tc_index = from->tc_index; 415 #endif 416 nf_copy(to, from); 417 #if defined(CONFIG_NETFILTER_XT_TARGET_TRACE) || \ 418 defined(CONFIG_NETFILTER_XT_TARGET_TRACE_MODULE) 419 to->nf_trace = from->nf_trace; 420 #endif 421 #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE) 422 to->ipvs_property = from->ipvs_property; 423 #endif 424 skb_copy_secmark(to, from); 425 } 426 427 /* 428 * This IP datagram is too large to be sent in one piece. Break it up into 429 * smaller pieces (each of size equal to IP header plus 430 * a block of the data of the original IP data part) that will yet fit in a 431 * single device frame, and queue such a frame for sending. 432 */ 433 434 int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *)) 435 { 436 struct iphdr *iph; 437 int raw = 0; 438 int ptr; 439 struct net_device *dev; 440 struct sk_buff *skb2; 441 unsigned int mtu, hlen, left, len, ll_rs, pad; 442 int offset; 443 __be16 not_last_frag; 444 struct rtable *rt = skb_rtable(skb); 445 int err = 0; 446 447 dev = rt->u.dst.dev; 448 449 /* 450 * Point into the IP datagram header. 451 */ 452 453 iph = ip_hdr(skb); 454 455 if (unlikely((iph->frag_off & htons(IP_DF)) && !skb->local_df)) { 456 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); 457 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, 458 htonl(ip_skb_dst_mtu(skb))); 459 kfree_skb(skb); 460 return -EMSGSIZE; 461 } 462 463 /* 464 * Setup starting values. 465 */ 466 467 hlen = iph->ihl * 4; 468 mtu = dst_mtu(&rt->u.dst) - hlen; /* Size of data space */ 469 IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE; 470 471 /* When frag_list is given, use it. First, check its validity: 472 * some transformers could create wrong frag_list or break existing 473 * one, it is not prohibited. In this case fall back to copying. 474 * 475 * LATER: this step can be merged to real generation of fragments, 476 * we can switch to copy when see the first bad fragment. 477 */ 478 if (skb_has_frags(skb)) { 479 struct sk_buff *frag; 480 int first_len = skb_pagelen(skb); 481 int truesizes = 0; 482 483 if (first_len - hlen > mtu || 484 ((first_len - hlen) & 7) || 485 (iph->frag_off & htons(IP_MF|IP_OFFSET)) || 486 skb_cloned(skb)) 487 goto slow_path; 488 489 skb_walk_frags(skb, frag) { 490 /* Correct geometry. */ 491 if (frag->len > mtu || 492 ((frag->len & 7) && frag->next) || 493 skb_headroom(frag) < hlen) 494 goto slow_path; 495 496 /* Partially cloned skb? */ 497 if (skb_shared(frag)) 498 goto slow_path; 499 500 BUG_ON(frag->sk); 501 if (skb->sk) { 502 frag->sk = skb->sk; 503 frag->destructor = sock_wfree; 504 truesizes += frag->truesize; 505 } 506 } 507 508 /* Everything is OK. Generate! */ 509 510 err = 0; 511 offset = 0; 512 frag = skb_shinfo(skb)->frag_list; 513 skb_frag_list_init(skb); 514 skb->data_len = first_len - skb_headlen(skb); 515 skb->truesize -= truesizes; 516 skb->len = first_len; 517 iph->tot_len = htons(first_len); 518 iph->frag_off = htons(IP_MF); 519 ip_send_check(iph); 520 521 for (;;) { 522 /* Prepare header of the next frame, 523 * before previous one went down. */ 524 if (frag) { 525 frag->ip_summed = CHECKSUM_NONE; 526 skb_reset_transport_header(frag); 527 __skb_push(frag, hlen); 528 skb_reset_network_header(frag); 529 memcpy(skb_network_header(frag), iph, hlen); 530 iph = ip_hdr(frag); 531 iph->tot_len = htons(frag->len); 532 ip_copy_metadata(frag, skb); 533 if (offset == 0) 534 ip_options_fragment(frag); 535 offset += skb->len - hlen; 536 iph->frag_off = htons(offset>>3); 537 if (frag->next != NULL) 538 iph->frag_off |= htons(IP_MF); 539 /* Ready, complete checksum */ 540 ip_send_check(iph); 541 } 542 543 err = output(skb); 544 545 if (!err) 546 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES); 547 if (err || !frag) 548 break; 549 550 skb = frag; 551 frag = skb->next; 552 skb->next = NULL; 553 } 554 555 if (err == 0) { 556 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS); 557 return 0; 558 } 559 560 while (frag) { 561 skb = frag->next; 562 kfree_skb(frag); 563 frag = skb; 564 } 565 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); 566 return err; 567 } 568 569 slow_path: 570 left = skb->len - hlen; /* Space per frame */ 571 ptr = raw + hlen; /* Where to start from */ 572 573 /* for bridged IP traffic encapsulated inside f.e. a vlan header, 574 * we need to make room for the encapsulating header 575 */ 576 pad = nf_bridge_pad(skb); 577 ll_rs = LL_RESERVED_SPACE_EXTRA(rt->u.dst.dev, pad); 578 mtu -= pad; 579 580 /* 581 * Fragment the datagram. 582 */ 583 584 offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3; 585 not_last_frag = iph->frag_off & htons(IP_MF); 586 587 /* 588 * Keep copying data until we run out. 589 */ 590 591 while (left > 0) { 592 len = left; 593 /* IF: it doesn't fit, use 'mtu' - the data space left */ 594 if (len > mtu) 595 len = mtu; 596 /* IF: we are not sending upto and including the packet end 597 then align the next start on an eight byte boundary */ 598 if (len < left) { 599 len &= ~7; 600 } 601 /* 602 * Allocate buffer. 603 */ 604 605 if ((skb2 = alloc_skb(len+hlen+ll_rs, GFP_ATOMIC)) == NULL) { 606 NETDEBUG(KERN_INFO "IP: frag: no memory for new fragment!\n"); 607 err = -ENOMEM; 608 goto fail; 609 } 610 611 /* 612 * Set up data on packet 613 */ 614 615 ip_copy_metadata(skb2, skb); 616 skb_reserve(skb2, ll_rs); 617 skb_put(skb2, len + hlen); 618 skb_reset_network_header(skb2); 619 skb2->transport_header = skb2->network_header + hlen; 620 621 /* 622 * Charge the memory for the fragment to any owner 623 * it might possess 624 */ 625 626 if (skb->sk) 627 skb_set_owner_w(skb2, skb->sk); 628 629 /* 630 * Copy the packet header into the new buffer. 631 */ 632 633 skb_copy_from_linear_data(skb, skb_network_header(skb2), hlen); 634 635 /* 636 * Copy a block of the IP datagram. 637 */ 638 if (skb_copy_bits(skb, ptr, skb_transport_header(skb2), len)) 639 BUG(); 640 left -= len; 641 642 /* 643 * Fill in the new header fields. 644 */ 645 iph = ip_hdr(skb2); 646 iph->frag_off = htons((offset >> 3)); 647 648 /* ANK: dirty, but effective trick. Upgrade options only if 649 * the segment to be fragmented was THE FIRST (otherwise, 650 * options are already fixed) and make it ONCE 651 * on the initial skb, so that all the following fragments 652 * will inherit fixed options. 653 */ 654 if (offset == 0) 655 ip_options_fragment(skb); 656 657 /* 658 * Added AC : If we are fragmenting a fragment that's not the 659 * last fragment then keep MF on each bit 660 */ 661 if (left > 0 || not_last_frag) 662 iph->frag_off |= htons(IP_MF); 663 ptr += len; 664 offset += len; 665 666 /* 667 * Put this fragment into the sending queue. 668 */ 669 iph->tot_len = htons(len + hlen); 670 671 ip_send_check(iph); 672 673 err = output(skb2); 674 if (err) 675 goto fail; 676 677 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES); 678 } 679 kfree_skb(skb); 680 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS); 681 return err; 682 683 fail: 684 kfree_skb(skb); 685 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); 686 return err; 687 } 688 689 EXPORT_SYMBOL(ip_fragment); 690 691 int 692 ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb) 693 { 694 struct iovec *iov = from; 695 696 if (skb->ip_summed == CHECKSUM_PARTIAL) { 697 if (memcpy_fromiovecend(to, iov, offset, len) < 0) 698 return -EFAULT; 699 } else { 700 __wsum csum = 0; 701 if (csum_partial_copy_fromiovecend(to, iov, offset, len, &csum) < 0) 702 return -EFAULT; 703 skb->csum = csum_block_add(skb->csum, csum, odd); 704 } 705 return 0; 706 } 707 708 static inline __wsum 709 csum_page(struct page *page, int offset, int copy) 710 { 711 char *kaddr; 712 __wsum csum; 713 kaddr = kmap(page); 714 csum = csum_partial(kaddr + offset, copy, 0); 715 kunmap(page); 716 return csum; 717 } 718 719 static inline int ip_ufo_append_data(struct sock *sk, 720 int getfrag(void *from, char *to, int offset, int len, 721 int odd, struct sk_buff *skb), 722 void *from, int length, int hh_len, int fragheaderlen, 723 int transhdrlen, int mtu, unsigned int flags) 724 { 725 struct sk_buff *skb; 726 int err; 727 728 /* There is support for UDP fragmentation offload by network 729 * device, so create one single skb packet containing complete 730 * udp datagram 731 */ 732 if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL) { 733 skb = sock_alloc_send_skb(sk, 734 hh_len + fragheaderlen + transhdrlen + 20, 735 (flags & MSG_DONTWAIT), &err); 736 737 if (skb == NULL) 738 return err; 739 740 /* reserve space for Hardware header */ 741 skb_reserve(skb, hh_len); 742 743 /* create space for UDP/IP header */ 744 skb_put(skb, fragheaderlen + transhdrlen); 745 746 /* initialize network header pointer */ 747 skb_reset_network_header(skb); 748 749 /* initialize protocol header pointer */ 750 skb->transport_header = skb->network_header + fragheaderlen; 751 752 skb->ip_summed = CHECKSUM_PARTIAL; 753 skb->csum = 0; 754 sk->sk_sndmsg_off = 0; 755 756 /* specify the length of each IP datagram fragment */ 757 skb_shinfo(skb)->gso_size = mtu - fragheaderlen; 758 skb_shinfo(skb)->gso_type = SKB_GSO_UDP; 759 __skb_queue_tail(&sk->sk_write_queue, skb); 760 } 761 762 return skb_append_datato_frags(sk, skb, getfrag, from, 763 (length - transhdrlen)); 764 } 765 766 /* 767 * ip_append_data() and ip_append_page() can make one large IP datagram 768 * from many pieces of data. Each pieces will be holded on the socket 769 * until ip_push_pending_frames() is called. Each piece can be a page 770 * or non-page data. 771 * 772 * Not only UDP, other transport protocols - e.g. raw sockets - can use 773 * this interface potentially. 774 * 775 * LATER: length must be adjusted by pad at tail, when it is required. 776 */ 777 int ip_append_data(struct sock *sk, 778 int getfrag(void *from, char *to, int offset, int len, 779 int odd, struct sk_buff *skb), 780 void *from, int length, int transhdrlen, 781 struct ipcm_cookie *ipc, struct rtable **rtp, 782 unsigned int flags) 783 { 784 struct inet_sock *inet = inet_sk(sk); 785 struct sk_buff *skb; 786 787 struct ip_options *opt = NULL; 788 int hh_len; 789 int exthdrlen; 790 int mtu; 791 int copy; 792 int err; 793 int offset = 0; 794 unsigned int maxfraglen, fragheaderlen; 795 int csummode = CHECKSUM_NONE; 796 struct rtable *rt; 797 798 if (flags&MSG_PROBE) 799 return 0; 800 801 if (skb_queue_empty(&sk->sk_write_queue)) { 802 /* 803 * setup for corking. 804 */ 805 opt = ipc->opt; 806 if (opt) { 807 if (inet->cork.opt == NULL) { 808 inet->cork.opt = kmalloc(sizeof(struct ip_options) + 40, sk->sk_allocation); 809 if (unlikely(inet->cork.opt == NULL)) 810 return -ENOBUFS; 811 } 812 memcpy(inet->cork.opt, opt, sizeof(struct ip_options)+opt->optlen); 813 inet->cork.flags |= IPCORK_OPT; 814 inet->cork.addr = ipc->addr; 815 } 816 rt = *rtp; 817 if (unlikely(!rt)) 818 return -EFAULT; 819 /* 820 * We steal reference to this route, caller should not release it 821 */ 822 *rtp = NULL; 823 inet->cork.fragsize = mtu = inet->pmtudisc == IP_PMTUDISC_PROBE ? 824 rt->u.dst.dev->mtu : 825 dst_mtu(rt->u.dst.path); 826 inet->cork.dst = &rt->u.dst; 827 inet->cork.length = 0; 828 sk->sk_sndmsg_page = NULL; 829 sk->sk_sndmsg_off = 0; 830 if ((exthdrlen = rt->u.dst.header_len) != 0) { 831 length += exthdrlen; 832 transhdrlen += exthdrlen; 833 } 834 } else { 835 rt = (struct rtable *)inet->cork.dst; 836 if (inet->cork.flags & IPCORK_OPT) 837 opt = inet->cork.opt; 838 839 transhdrlen = 0; 840 exthdrlen = 0; 841 mtu = inet->cork.fragsize; 842 } 843 hh_len = LL_RESERVED_SPACE(rt->u.dst.dev); 844 845 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0); 846 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen; 847 848 if (inet->cork.length + length > 0xFFFF - fragheaderlen) { 849 ip_local_error(sk, EMSGSIZE, rt->rt_dst, inet->dport, mtu-exthdrlen); 850 return -EMSGSIZE; 851 } 852 853 /* 854 * transhdrlen > 0 means that this is the first fragment and we wish 855 * it won't be fragmented in the future. 856 */ 857 if (transhdrlen && 858 length + fragheaderlen <= mtu && 859 rt->u.dst.dev->features & NETIF_F_V4_CSUM && 860 !exthdrlen) 861 csummode = CHECKSUM_PARTIAL; 862 863 inet->cork.length += length; 864 if (((length> mtu) || !skb_queue_empty(&sk->sk_write_queue)) && 865 (sk->sk_protocol == IPPROTO_UDP) && 866 (rt->u.dst.dev->features & NETIF_F_UFO)) { 867 err = ip_ufo_append_data(sk, getfrag, from, length, hh_len, 868 fragheaderlen, transhdrlen, mtu, 869 flags); 870 if (err) 871 goto error; 872 return 0; 873 } 874 875 /* So, what's going on in the loop below? 876 * 877 * We use calculated fragment length to generate chained skb, 878 * each of segments is IP fragment ready for sending to network after 879 * adding appropriate IP header. 880 */ 881 882 if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL) 883 goto alloc_new_skb; 884 885 while (length > 0) { 886 /* Check if the remaining data fits into current packet. */ 887 copy = mtu - skb->len; 888 if (copy < length) 889 copy = maxfraglen - skb->len; 890 if (copy <= 0) { 891 char *data; 892 unsigned int datalen; 893 unsigned int fraglen; 894 unsigned int fraggap; 895 unsigned int alloclen; 896 struct sk_buff *skb_prev; 897 alloc_new_skb: 898 skb_prev = skb; 899 if (skb_prev) 900 fraggap = skb_prev->len - maxfraglen; 901 else 902 fraggap = 0; 903 904 /* 905 * If remaining data exceeds the mtu, 906 * we know we need more fragment(s). 907 */ 908 datalen = length + fraggap; 909 if (datalen > mtu - fragheaderlen) 910 datalen = maxfraglen - fragheaderlen; 911 fraglen = datalen + fragheaderlen; 912 913 if ((flags & MSG_MORE) && 914 !(rt->u.dst.dev->features&NETIF_F_SG)) 915 alloclen = mtu; 916 else 917 alloclen = datalen + fragheaderlen; 918 919 /* The last fragment gets additional space at tail. 920 * Note, with MSG_MORE we overallocate on fragments, 921 * because we have no idea what fragment will be 922 * the last. 923 */ 924 if (datalen == length + fraggap) 925 alloclen += rt->u.dst.trailer_len; 926 927 if (transhdrlen) { 928 skb = sock_alloc_send_skb(sk, 929 alloclen + hh_len + 15, 930 (flags & MSG_DONTWAIT), &err); 931 } else { 932 skb = NULL; 933 if (atomic_read(&sk->sk_wmem_alloc) <= 934 2 * sk->sk_sndbuf) 935 skb = sock_wmalloc(sk, 936 alloclen + hh_len + 15, 1, 937 sk->sk_allocation); 938 if (unlikely(skb == NULL)) 939 err = -ENOBUFS; 940 else 941 /* only the initial fragment is 942 time stamped */ 943 ipc->shtx.flags = 0; 944 } 945 if (skb == NULL) 946 goto error; 947 948 /* 949 * Fill in the control structures 950 */ 951 skb->ip_summed = csummode; 952 skb->csum = 0; 953 skb_reserve(skb, hh_len); 954 *skb_tx(skb) = ipc->shtx; 955 956 /* 957 * Find where to start putting bytes. 958 */ 959 data = skb_put(skb, fraglen); 960 skb_set_network_header(skb, exthdrlen); 961 skb->transport_header = (skb->network_header + 962 fragheaderlen); 963 data += fragheaderlen; 964 965 if (fraggap) { 966 skb->csum = skb_copy_and_csum_bits( 967 skb_prev, maxfraglen, 968 data + transhdrlen, fraggap, 0); 969 skb_prev->csum = csum_sub(skb_prev->csum, 970 skb->csum); 971 data += fraggap; 972 pskb_trim_unique(skb_prev, maxfraglen); 973 } 974 975 copy = datalen - transhdrlen - fraggap; 976 if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) { 977 err = -EFAULT; 978 kfree_skb(skb); 979 goto error; 980 } 981 982 offset += copy; 983 length -= datalen - fraggap; 984 transhdrlen = 0; 985 exthdrlen = 0; 986 csummode = CHECKSUM_NONE; 987 988 /* 989 * Put the packet on the pending queue. 990 */ 991 __skb_queue_tail(&sk->sk_write_queue, skb); 992 continue; 993 } 994 995 if (copy > length) 996 copy = length; 997 998 if (!(rt->u.dst.dev->features&NETIF_F_SG)) { 999 unsigned int off; 1000 1001 off = skb->len; 1002 if (getfrag(from, skb_put(skb, copy), 1003 offset, copy, off, skb) < 0) { 1004 __skb_trim(skb, off); 1005 err = -EFAULT; 1006 goto error; 1007 } 1008 } else { 1009 int i = skb_shinfo(skb)->nr_frags; 1010 skb_frag_t *frag = &skb_shinfo(skb)->frags[i-1]; 1011 struct page *page = sk->sk_sndmsg_page; 1012 int off = sk->sk_sndmsg_off; 1013 unsigned int left; 1014 1015 if (page && (left = PAGE_SIZE - off) > 0) { 1016 if (copy >= left) 1017 copy = left; 1018 if (page != frag->page) { 1019 if (i == MAX_SKB_FRAGS) { 1020 err = -EMSGSIZE; 1021 goto error; 1022 } 1023 get_page(page); 1024 skb_fill_page_desc(skb, i, page, sk->sk_sndmsg_off, 0); 1025 frag = &skb_shinfo(skb)->frags[i]; 1026 } 1027 } else if (i < MAX_SKB_FRAGS) { 1028 if (copy > PAGE_SIZE) 1029 copy = PAGE_SIZE; 1030 page = alloc_pages(sk->sk_allocation, 0); 1031 if (page == NULL) { 1032 err = -ENOMEM; 1033 goto error; 1034 } 1035 sk->sk_sndmsg_page = page; 1036 sk->sk_sndmsg_off = 0; 1037 1038 skb_fill_page_desc(skb, i, page, 0, 0); 1039 frag = &skb_shinfo(skb)->frags[i]; 1040 } else { 1041 err = -EMSGSIZE; 1042 goto error; 1043 } 1044 if (getfrag(from, page_address(frag->page)+frag->page_offset+frag->size, offset, copy, skb->len, skb) < 0) { 1045 err = -EFAULT; 1046 goto error; 1047 } 1048 sk->sk_sndmsg_off += copy; 1049 frag->size += copy; 1050 skb->len += copy; 1051 skb->data_len += copy; 1052 skb->truesize += copy; 1053 atomic_add(copy, &sk->sk_wmem_alloc); 1054 } 1055 offset += copy; 1056 length -= copy; 1057 } 1058 1059 return 0; 1060 1061 error: 1062 inet->cork.length -= length; 1063 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS); 1064 return err; 1065 } 1066 1067 ssize_t ip_append_page(struct sock *sk, struct page *page, 1068 int offset, size_t size, int flags) 1069 { 1070 struct inet_sock *inet = inet_sk(sk); 1071 struct sk_buff *skb; 1072 struct rtable *rt; 1073 struct ip_options *opt = NULL; 1074 int hh_len; 1075 int mtu; 1076 int len; 1077 int err; 1078 unsigned int maxfraglen, fragheaderlen, fraggap; 1079 1080 if (inet->hdrincl) 1081 return -EPERM; 1082 1083 if (flags&MSG_PROBE) 1084 return 0; 1085 1086 if (skb_queue_empty(&sk->sk_write_queue)) 1087 return -EINVAL; 1088 1089 rt = (struct rtable *)inet->cork.dst; 1090 if (inet->cork.flags & IPCORK_OPT) 1091 opt = inet->cork.opt; 1092 1093 if (!(rt->u.dst.dev->features&NETIF_F_SG)) 1094 return -EOPNOTSUPP; 1095 1096 hh_len = LL_RESERVED_SPACE(rt->u.dst.dev); 1097 mtu = inet->cork.fragsize; 1098 1099 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0); 1100 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen; 1101 1102 if (inet->cork.length + size > 0xFFFF - fragheaderlen) { 1103 ip_local_error(sk, EMSGSIZE, rt->rt_dst, inet->dport, mtu); 1104 return -EMSGSIZE; 1105 } 1106 1107 if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL) 1108 return -EINVAL; 1109 1110 inet->cork.length += size; 1111 if ((sk->sk_protocol == IPPROTO_UDP) && 1112 (rt->u.dst.dev->features & NETIF_F_UFO)) { 1113 skb_shinfo(skb)->gso_size = mtu - fragheaderlen; 1114 skb_shinfo(skb)->gso_type = SKB_GSO_UDP; 1115 } 1116 1117 1118 while (size > 0) { 1119 int i; 1120 1121 if (skb_is_gso(skb)) 1122 len = size; 1123 else { 1124 1125 /* Check if the remaining data fits into current packet. */ 1126 len = mtu - skb->len; 1127 if (len < size) 1128 len = maxfraglen - skb->len; 1129 } 1130 if (len <= 0) { 1131 struct sk_buff *skb_prev; 1132 int alloclen; 1133 1134 skb_prev = skb; 1135 fraggap = skb_prev->len - maxfraglen; 1136 1137 alloclen = fragheaderlen + hh_len + fraggap + 15; 1138 skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation); 1139 if (unlikely(!skb)) { 1140 err = -ENOBUFS; 1141 goto error; 1142 } 1143 1144 /* 1145 * Fill in the control structures 1146 */ 1147 skb->ip_summed = CHECKSUM_NONE; 1148 skb->csum = 0; 1149 skb_reserve(skb, hh_len); 1150 1151 /* 1152 * Find where to start putting bytes. 1153 */ 1154 skb_put(skb, fragheaderlen + fraggap); 1155 skb_reset_network_header(skb); 1156 skb->transport_header = (skb->network_header + 1157 fragheaderlen); 1158 if (fraggap) { 1159 skb->csum = skb_copy_and_csum_bits(skb_prev, 1160 maxfraglen, 1161 skb_transport_header(skb), 1162 fraggap, 0); 1163 skb_prev->csum = csum_sub(skb_prev->csum, 1164 skb->csum); 1165 pskb_trim_unique(skb_prev, maxfraglen); 1166 } 1167 1168 /* 1169 * Put the packet on the pending queue. 1170 */ 1171 __skb_queue_tail(&sk->sk_write_queue, skb); 1172 continue; 1173 } 1174 1175 i = skb_shinfo(skb)->nr_frags; 1176 if (len > size) 1177 len = size; 1178 if (skb_can_coalesce(skb, i, page, offset)) { 1179 skb_shinfo(skb)->frags[i-1].size += len; 1180 } else if (i < MAX_SKB_FRAGS) { 1181 get_page(page); 1182 skb_fill_page_desc(skb, i, page, offset, len); 1183 } else { 1184 err = -EMSGSIZE; 1185 goto error; 1186 } 1187 1188 if (skb->ip_summed == CHECKSUM_NONE) { 1189 __wsum csum; 1190 csum = csum_page(page, offset, len); 1191 skb->csum = csum_block_add(skb->csum, csum, skb->len); 1192 } 1193 1194 skb->len += len; 1195 skb->data_len += len; 1196 skb->truesize += len; 1197 atomic_add(len, &sk->sk_wmem_alloc); 1198 offset += len; 1199 size -= len; 1200 } 1201 return 0; 1202 1203 error: 1204 inet->cork.length -= size; 1205 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS); 1206 return err; 1207 } 1208 1209 static void ip_cork_release(struct inet_sock *inet) 1210 { 1211 inet->cork.flags &= ~IPCORK_OPT; 1212 kfree(inet->cork.opt); 1213 inet->cork.opt = NULL; 1214 dst_release(inet->cork.dst); 1215 inet->cork.dst = NULL; 1216 } 1217 1218 /* 1219 * Combined all pending IP fragments on the socket as one IP datagram 1220 * and push them out. 1221 */ 1222 int ip_push_pending_frames(struct sock *sk) 1223 { 1224 struct sk_buff *skb, *tmp_skb; 1225 struct sk_buff **tail_skb; 1226 struct inet_sock *inet = inet_sk(sk); 1227 struct net *net = sock_net(sk); 1228 struct ip_options *opt = NULL; 1229 struct rtable *rt = (struct rtable *)inet->cork.dst; 1230 struct iphdr *iph; 1231 __be16 df = 0; 1232 __u8 ttl; 1233 int err = 0; 1234 1235 if ((skb = __skb_dequeue(&sk->sk_write_queue)) == NULL) 1236 goto out; 1237 tail_skb = &(skb_shinfo(skb)->frag_list); 1238 1239 /* move skb->data to ip header from ext header */ 1240 if (skb->data < skb_network_header(skb)) 1241 __skb_pull(skb, skb_network_offset(skb)); 1242 while ((tmp_skb = __skb_dequeue(&sk->sk_write_queue)) != NULL) { 1243 __skb_pull(tmp_skb, skb_network_header_len(skb)); 1244 *tail_skb = tmp_skb; 1245 tail_skb = &(tmp_skb->next); 1246 skb->len += tmp_skb->len; 1247 skb->data_len += tmp_skb->len; 1248 skb->truesize += tmp_skb->truesize; 1249 tmp_skb->destructor = NULL; 1250 tmp_skb->sk = NULL; 1251 } 1252 1253 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow 1254 * to fragment the frame generated here. No matter, what transforms 1255 * how transforms change size of the packet, it will come out. 1256 */ 1257 if (inet->pmtudisc < IP_PMTUDISC_DO) 1258 skb->local_df = 1; 1259 1260 /* DF bit is set when we want to see DF on outgoing frames. 1261 * If local_df is set too, we still allow to fragment this frame 1262 * locally. */ 1263 if (inet->pmtudisc >= IP_PMTUDISC_DO || 1264 (skb->len <= dst_mtu(&rt->u.dst) && 1265 ip_dont_fragment(sk, &rt->u.dst))) 1266 df = htons(IP_DF); 1267 1268 if (inet->cork.flags & IPCORK_OPT) 1269 opt = inet->cork.opt; 1270 1271 if (rt->rt_type == RTN_MULTICAST) 1272 ttl = inet->mc_ttl; 1273 else 1274 ttl = ip_select_ttl(inet, &rt->u.dst); 1275 1276 iph = (struct iphdr *)skb->data; 1277 iph->version = 4; 1278 iph->ihl = 5; 1279 if (opt) { 1280 iph->ihl += opt->optlen>>2; 1281 ip_options_build(skb, opt, inet->cork.addr, rt, 0); 1282 } 1283 iph->tos = inet->tos; 1284 iph->frag_off = df; 1285 ip_select_ident(iph, &rt->u.dst, sk); 1286 iph->ttl = ttl; 1287 iph->protocol = sk->sk_protocol; 1288 iph->saddr = rt->rt_src; 1289 iph->daddr = rt->rt_dst; 1290 1291 skb->priority = sk->sk_priority; 1292 skb->mark = sk->sk_mark; 1293 /* 1294 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec 1295 * on dst refcount 1296 */ 1297 inet->cork.dst = NULL; 1298 skb_dst_set(skb, &rt->u.dst); 1299 1300 if (iph->protocol == IPPROTO_ICMP) 1301 icmp_out_count(net, ((struct icmphdr *) 1302 skb_transport_header(skb))->type); 1303 1304 /* Netfilter gets whole the not fragmented skb. */ 1305 err = ip_local_out(skb); 1306 if (err) { 1307 if (err > 0) 1308 err = net_xmit_errno(err); 1309 if (err) 1310 goto error; 1311 } 1312 1313 out: 1314 ip_cork_release(inet); 1315 return err; 1316 1317 error: 1318 IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS); 1319 goto out; 1320 } 1321 1322 /* 1323 * Throw away all pending data on the socket. 1324 */ 1325 void ip_flush_pending_frames(struct sock *sk) 1326 { 1327 struct sk_buff *skb; 1328 1329 while ((skb = __skb_dequeue_tail(&sk->sk_write_queue)) != NULL) 1330 kfree_skb(skb); 1331 1332 ip_cork_release(inet_sk(sk)); 1333 } 1334 1335 1336 /* 1337 * Fetch data from kernel space and fill in checksum if needed. 1338 */ 1339 static int ip_reply_glue_bits(void *dptr, char *to, int offset, 1340 int len, int odd, struct sk_buff *skb) 1341 { 1342 __wsum csum; 1343 1344 csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0); 1345 skb->csum = csum_block_add(skb->csum, csum, odd); 1346 return 0; 1347 } 1348 1349 /* 1350 * Generic function to send a packet as reply to another packet. 1351 * Used to send TCP resets so far. ICMP should use this function too. 1352 * 1353 * Should run single threaded per socket because it uses the sock 1354 * structure to pass arguments. 1355 */ 1356 void ip_send_reply(struct sock *sk, struct sk_buff *skb, struct ip_reply_arg *arg, 1357 unsigned int len) 1358 { 1359 struct inet_sock *inet = inet_sk(sk); 1360 struct { 1361 struct ip_options opt; 1362 char data[40]; 1363 } replyopts; 1364 struct ipcm_cookie ipc; 1365 __be32 daddr; 1366 struct rtable *rt = skb_rtable(skb); 1367 1368 if (ip_options_echo(&replyopts.opt, skb)) 1369 return; 1370 1371 daddr = ipc.addr = rt->rt_src; 1372 ipc.opt = NULL; 1373 ipc.shtx.flags = 0; 1374 1375 if (replyopts.opt.optlen) { 1376 ipc.opt = &replyopts.opt; 1377 1378 if (ipc.opt->srr) 1379 daddr = replyopts.opt.faddr; 1380 } 1381 1382 { 1383 struct flowi fl = { .oif = arg->bound_dev_if, 1384 .nl_u = { .ip4_u = 1385 { .daddr = daddr, 1386 .saddr = rt->rt_spec_dst, 1387 .tos = RT_TOS(ip_hdr(skb)->tos) } }, 1388 /* Not quite clean, but right. */ 1389 .uli_u = { .ports = 1390 { .sport = tcp_hdr(skb)->dest, 1391 .dport = tcp_hdr(skb)->source } }, 1392 .proto = sk->sk_protocol, 1393 .flags = ip_reply_arg_flowi_flags(arg) }; 1394 security_skb_classify_flow(skb, &fl); 1395 if (ip_route_output_key(sock_net(sk), &rt, &fl)) 1396 return; 1397 } 1398 1399 /* And let IP do all the hard work. 1400 1401 This chunk is not reenterable, hence spinlock. 1402 Note that it uses the fact, that this function is called 1403 with locally disabled BH and that sk cannot be already spinlocked. 1404 */ 1405 bh_lock_sock(sk); 1406 inet->tos = ip_hdr(skb)->tos; 1407 sk->sk_priority = skb->priority; 1408 sk->sk_protocol = ip_hdr(skb)->protocol; 1409 sk->sk_bound_dev_if = arg->bound_dev_if; 1410 ip_append_data(sk, ip_reply_glue_bits, arg->iov->iov_base, len, 0, 1411 &ipc, &rt, MSG_DONTWAIT); 1412 if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) { 1413 if (arg->csumoffset >= 0) 1414 *((__sum16 *)skb_transport_header(skb) + 1415 arg->csumoffset) = csum_fold(csum_add(skb->csum, 1416 arg->csum)); 1417 skb->ip_summed = CHECKSUM_NONE; 1418 ip_push_pending_frames(sk); 1419 } 1420 1421 bh_unlock_sock(sk); 1422 1423 ip_rt_put(rt); 1424 } 1425 1426 void __init ip_init(void) 1427 { 1428 ip_rt_init(); 1429 inet_initpeers(); 1430 1431 #if defined(CONFIG_IP_MULTICAST) && defined(CONFIG_PROC_FS) 1432 igmp_mc_proc_init(); 1433 #endif 1434 } 1435 1436 EXPORT_SYMBOL(ip_generic_getfrag); 1437 EXPORT_SYMBOL(ip_queue_xmit); 1438 EXPORT_SYMBOL(ip_send_check); 1439