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 EXPORT_SYMBOL(ip_send_check); 93 94 int __ip_local_out(struct sk_buff *skb) 95 { 96 struct iphdr *iph = ip_hdr(skb); 97 98 iph->tot_len = htons(skb->len); 99 ip_send_check(iph); 100 return nf_hook(NFPROTO_IPV4, NF_INET_LOCAL_OUT, skb, NULL, 101 skb_dst(skb)->dev, dst_output); 102 } 103 104 int ip_local_out(struct sk_buff *skb) 105 { 106 int err; 107 108 err = __ip_local_out(skb); 109 if (likely(err == 1)) 110 err = dst_output(skb); 111 112 return err; 113 } 114 EXPORT_SYMBOL_GPL(ip_local_out); 115 116 /* dev_loopback_xmit for use with netfilter. */ 117 static int ip_dev_loopback_xmit(struct sk_buff *newskb) 118 { 119 skb_reset_mac_header(newskb); 120 __skb_pull(newskb, skb_network_offset(newskb)); 121 newskb->pkt_type = PACKET_LOOPBACK; 122 newskb->ip_summed = CHECKSUM_UNNECESSARY; 123 WARN_ON(!skb_dst(newskb)); 124 netif_rx_ni(newskb); 125 return 0; 126 } 127 128 static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst) 129 { 130 int ttl = inet->uc_ttl; 131 132 if (ttl < 0) 133 ttl = dst_metric(dst, RTAX_HOPLIMIT); 134 return ttl; 135 } 136 137 /* 138 * Add an ip header to a skbuff and send it out. 139 * 140 */ 141 int ip_build_and_send_pkt(struct sk_buff *skb, struct sock *sk, 142 __be32 saddr, __be32 daddr, struct ip_options *opt) 143 { 144 struct inet_sock *inet = inet_sk(sk); 145 struct rtable *rt = skb_rtable(skb); 146 struct iphdr *iph; 147 148 /* Build the IP header. */ 149 skb_push(skb, sizeof(struct iphdr) + (opt ? opt->optlen : 0)); 150 skb_reset_network_header(skb); 151 iph = ip_hdr(skb); 152 iph->version = 4; 153 iph->ihl = 5; 154 iph->tos = inet->tos; 155 if (ip_dont_fragment(sk, &rt->dst)) 156 iph->frag_off = htons(IP_DF); 157 else 158 iph->frag_off = 0; 159 iph->ttl = ip_select_ttl(inet, &rt->dst); 160 iph->daddr = rt->rt_dst; 161 iph->saddr = rt->rt_src; 162 iph->protocol = sk->sk_protocol; 163 ip_select_ident(iph, &rt->dst, sk); 164 165 if (opt && opt->optlen) { 166 iph->ihl += opt->optlen>>2; 167 ip_options_build(skb, opt, daddr, rt, 0); 168 } 169 170 skb->priority = sk->sk_priority; 171 skb->mark = sk->sk_mark; 172 173 /* Send it out. */ 174 return ip_local_out(skb); 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->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->dst); 363 } 364 skb_dst_set_noref(skb, &rt->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->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->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->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 EXPORT_SYMBOL(ip_queue_xmit); 407 408 409 static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from) 410 { 411 to->pkt_type = from->pkt_type; 412 to->priority = from->priority; 413 to->protocol = from->protocol; 414 skb_dst_drop(to); 415 skb_dst_copy(to, from); 416 to->dev = from->dev; 417 to->mark = from->mark; 418 419 /* Copy the flags to each fragment. */ 420 IPCB(to)->flags = IPCB(from)->flags; 421 422 #ifdef CONFIG_NET_SCHED 423 to->tc_index = from->tc_index; 424 #endif 425 nf_copy(to, from); 426 #if defined(CONFIG_NETFILTER_XT_TARGET_TRACE) || \ 427 defined(CONFIG_NETFILTER_XT_TARGET_TRACE_MODULE) 428 to->nf_trace = from->nf_trace; 429 #endif 430 #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE) 431 to->ipvs_property = from->ipvs_property; 432 #endif 433 skb_copy_secmark(to, from); 434 } 435 436 /* 437 * This IP datagram is too large to be sent in one piece. Break it up into 438 * smaller pieces (each of size equal to IP header plus 439 * a block of the data of the original IP data part) that will yet fit in a 440 * single device frame, and queue such a frame for sending. 441 */ 442 443 int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *)) 444 { 445 struct iphdr *iph; 446 int ptr; 447 struct net_device *dev; 448 struct sk_buff *skb2; 449 unsigned int mtu, hlen, left, len, ll_rs; 450 int offset; 451 __be16 not_last_frag; 452 struct rtable *rt = skb_rtable(skb); 453 int err = 0; 454 455 dev = rt->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->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_frag_list(skb)) { 491 struct sk_buff *frag, *frag2; 492 int first_len = skb_pagelen(skb); 493 494 if (first_len - hlen > mtu || 495 ((first_len - hlen) & 7) || 496 (iph->frag_off & htons(IP_MF|IP_OFFSET)) || 497 skb_cloned(skb)) 498 goto slow_path; 499 500 skb_walk_frags(skb, frag) { 501 /* Correct geometry. */ 502 if (frag->len > mtu || 503 ((frag->len & 7) && frag->next) || 504 skb_headroom(frag) < hlen) 505 goto slow_path_clean; 506 507 /* Partially cloned skb? */ 508 if (skb_shared(frag)) 509 goto slow_path_clean; 510 511 BUG_ON(frag->sk); 512 if (skb->sk) { 513 frag->sk = skb->sk; 514 frag->destructor = sock_wfree; 515 } 516 skb->truesize -= frag->truesize; 517 } 518 519 /* Everything is OK. Generate! */ 520 521 err = 0; 522 offset = 0; 523 frag = skb_shinfo(skb)->frag_list; 524 skb_frag_list_init(skb); 525 skb->data_len = first_len - skb_headlen(skb); 526 skb->len = first_len; 527 iph->tot_len = htons(first_len); 528 iph->frag_off = htons(IP_MF); 529 ip_send_check(iph); 530 531 for (;;) { 532 /* Prepare header of the next frame, 533 * before previous one went down. */ 534 if (frag) { 535 frag->ip_summed = CHECKSUM_NONE; 536 skb_reset_transport_header(frag); 537 __skb_push(frag, hlen); 538 skb_reset_network_header(frag); 539 memcpy(skb_network_header(frag), iph, hlen); 540 iph = ip_hdr(frag); 541 iph->tot_len = htons(frag->len); 542 ip_copy_metadata(frag, skb); 543 if (offset == 0) 544 ip_options_fragment(frag); 545 offset += skb->len - hlen; 546 iph->frag_off = htons(offset>>3); 547 if (frag->next != NULL) 548 iph->frag_off |= htons(IP_MF); 549 /* Ready, complete checksum */ 550 ip_send_check(iph); 551 } 552 553 err = output(skb); 554 555 if (!err) 556 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES); 557 if (err || !frag) 558 break; 559 560 skb = frag; 561 frag = skb->next; 562 skb->next = NULL; 563 } 564 565 if (err == 0) { 566 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS); 567 return 0; 568 } 569 570 while (frag) { 571 skb = frag->next; 572 kfree_skb(frag); 573 frag = skb; 574 } 575 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); 576 return err; 577 578 slow_path_clean: 579 skb_walk_frags(skb, frag2) { 580 if (frag2 == frag) 581 break; 582 frag2->sk = NULL; 583 frag2->destructor = NULL; 584 skb->truesize += frag2->truesize; 585 } 586 } 587 588 slow_path: 589 left = skb->len - hlen; /* Space per frame */ 590 ptr = hlen; /* Where to start from */ 591 592 /* for bridged IP traffic encapsulated inside f.e. a vlan header, 593 * we need to make room for the encapsulating header 594 */ 595 ll_rs = LL_RESERVED_SPACE_EXTRA(rt->dst.dev, nf_bridge_pad(skb)); 596 597 /* 598 * Fragment the datagram. 599 */ 600 601 offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3; 602 not_last_frag = iph->frag_off & htons(IP_MF); 603 604 /* 605 * Keep copying data until we run out. 606 */ 607 608 while (left > 0) { 609 len = left; 610 /* IF: it doesn't fit, use 'mtu' - the data space left */ 611 if (len > mtu) 612 len = mtu; 613 /* IF: we are not sending upto and including the packet end 614 then align the next start on an eight byte boundary */ 615 if (len < left) { 616 len &= ~7; 617 } 618 /* 619 * Allocate buffer. 620 */ 621 622 if ((skb2 = alloc_skb(len+hlen+ll_rs, GFP_ATOMIC)) == NULL) { 623 NETDEBUG(KERN_INFO "IP: frag: no memory for new fragment!\n"); 624 err = -ENOMEM; 625 goto fail; 626 } 627 628 /* 629 * Set up data on packet 630 */ 631 632 ip_copy_metadata(skb2, skb); 633 skb_reserve(skb2, ll_rs); 634 skb_put(skb2, len + hlen); 635 skb_reset_network_header(skb2); 636 skb2->transport_header = skb2->network_header + hlen; 637 638 /* 639 * Charge the memory for the fragment to any owner 640 * it might possess 641 */ 642 643 if (skb->sk) 644 skb_set_owner_w(skb2, skb->sk); 645 646 /* 647 * Copy the packet header into the new buffer. 648 */ 649 650 skb_copy_from_linear_data(skb, skb_network_header(skb2), hlen); 651 652 /* 653 * Copy a block of the IP datagram. 654 */ 655 if (skb_copy_bits(skb, ptr, skb_transport_header(skb2), len)) 656 BUG(); 657 left -= len; 658 659 /* 660 * Fill in the new header fields. 661 */ 662 iph = ip_hdr(skb2); 663 iph->frag_off = htons((offset >> 3)); 664 665 /* ANK: dirty, but effective trick. Upgrade options only if 666 * the segment to be fragmented was THE FIRST (otherwise, 667 * options are already fixed) and make it ONCE 668 * on the initial skb, so that all the following fragments 669 * will inherit fixed options. 670 */ 671 if (offset == 0) 672 ip_options_fragment(skb); 673 674 /* 675 * Added AC : If we are fragmenting a fragment that's not the 676 * last fragment then keep MF on each bit 677 */ 678 if (left > 0 || not_last_frag) 679 iph->frag_off |= htons(IP_MF); 680 ptr += len; 681 offset += len; 682 683 /* 684 * Put this fragment into the sending queue. 685 */ 686 iph->tot_len = htons(len + hlen); 687 688 ip_send_check(iph); 689 690 err = output(skb2); 691 if (err) 692 goto fail; 693 694 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES); 695 } 696 kfree_skb(skb); 697 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS); 698 return err; 699 700 fail: 701 kfree_skb(skb); 702 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); 703 return err; 704 } 705 EXPORT_SYMBOL(ip_fragment); 706 707 int 708 ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb) 709 { 710 struct iovec *iov = from; 711 712 if (skb->ip_summed == CHECKSUM_PARTIAL) { 713 if (memcpy_fromiovecend(to, iov, offset, len) < 0) 714 return -EFAULT; 715 } else { 716 __wsum csum = 0; 717 if (csum_partial_copy_fromiovecend(to, iov, offset, len, &csum) < 0) 718 return -EFAULT; 719 skb->csum = csum_block_add(skb->csum, csum, odd); 720 } 721 return 0; 722 } 723 EXPORT_SYMBOL(ip_generic_getfrag); 724 725 static inline __wsum 726 csum_page(struct page *page, int offset, int copy) 727 { 728 char *kaddr; 729 __wsum csum; 730 kaddr = kmap(page); 731 csum = csum_partial(kaddr + offset, copy, 0); 732 kunmap(page); 733 return csum; 734 } 735 736 static inline int ip_ufo_append_data(struct sock *sk, 737 int getfrag(void *from, char *to, int offset, int len, 738 int odd, struct sk_buff *skb), 739 void *from, int length, int hh_len, int fragheaderlen, 740 int transhdrlen, int mtu, unsigned int flags) 741 { 742 struct sk_buff *skb; 743 int err; 744 745 /* There is support for UDP fragmentation offload by network 746 * device, so create one single skb packet containing complete 747 * udp datagram 748 */ 749 if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL) { 750 skb = sock_alloc_send_skb(sk, 751 hh_len + fragheaderlen + transhdrlen + 20, 752 (flags & MSG_DONTWAIT), &err); 753 754 if (skb == NULL) 755 return err; 756 757 /* reserve space for Hardware header */ 758 skb_reserve(skb, hh_len); 759 760 /* create space for UDP/IP header */ 761 skb_put(skb, fragheaderlen + transhdrlen); 762 763 /* initialize network header pointer */ 764 skb_reset_network_header(skb); 765 766 /* initialize protocol header pointer */ 767 skb->transport_header = skb->network_header + fragheaderlen; 768 769 skb->ip_summed = CHECKSUM_PARTIAL; 770 skb->csum = 0; 771 sk->sk_sndmsg_off = 0; 772 773 /* specify the length of each IP datagram fragment */ 774 skb_shinfo(skb)->gso_size = mtu - fragheaderlen; 775 skb_shinfo(skb)->gso_type = SKB_GSO_UDP; 776 __skb_queue_tail(&sk->sk_write_queue, skb); 777 } 778 779 return skb_append_datato_frags(sk, skb, getfrag, from, 780 (length - transhdrlen)); 781 } 782 783 /* 784 * ip_append_data() and ip_append_page() can make one large IP datagram 785 * from many pieces of data. Each pieces will be holded on the socket 786 * until ip_push_pending_frames() is called. Each piece can be a page 787 * or non-page data. 788 * 789 * Not only UDP, other transport protocols - e.g. raw sockets - can use 790 * this interface potentially. 791 * 792 * LATER: length must be adjusted by pad at tail, when it is required. 793 */ 794 int ip_append_data(struct sock *sk, 795 int getfrag(void *from, char *to, int offset, int len, 796 int odd, struct sk_buff *skb), 797 void *from, int length, int transhdrlen, 798 struct ipcm_cookie *ipc, struct rtable **rtp, 799 unsigned int flags) 800 { 801 struct inet_sock *inet = inet_sk(sk); 802 struct sk_buff *skb; 803 804 struct ip_options *opt = NULL; 805 int hh_len; 806 int exthdrlen; 807 int mtu; 808 int copy; 809 int err; 810 int offset = 0; 811 unsigned int maxfraglen, fragheaderlen; 812 int csummode = CHECKSUM_NONE; 813 struct rtable *rt; 814 815 if (flags&MSG_PROBE) 816 return 0; 817 818 if (skb_queue_empty(&sk->sk_write_queue)) { 819 /* 820 * setup for corking. 821 */ 822 opt = ipc->opt; 823 if (opt) { 824 if (inet->cork.opt == NULL) { 825 inet->cork.opt = kmalloc(sizeof(struct ip_options) + 40, sk->sk_allocation); 826 if (unlikely(inet->cork.opt == NULL)) 827 return -ENOBUFS; 828 } 829 memcpy(inet->cork.opt, opt, sizeof(struct ip_options)+opt->optlen); 830 inet->cork.flags |= IPCORK_OPT; 831 inet->cork.addr = ipc->addr; 832 } 833 rt = *rtp; 834 if (unlikely(!rt)) 835 return -EFAULT; 836 /* 837 * We steal reference to this route, caller should not release it 838 */ 839 *rtp = NULL; 840 inet->cork.fragsize = mtu = inet->pmtudisc == IP_PMTUDISC_PROBE ? 841 rt->dst.dev->mtu : 842 dst_mtu(rt->dst.path); 843 inet->cork.dst = &rt->dst; 844 inet->cork.length = 0; 845 sk->sk_sndmsg_page = NULL; 846 sk->sk_sndmsg_off = 0; 847 exthdrlen = rt->dst.header_len; 848 length += exthdrlen; 849 transhdrlen += exthdrlen; 850 } else { 851 rt = (struct rtable *)inet->cork.dst; 852 if (inet->cork.flags & IPCORK_OPT) 853 opt = inet->cork.opt; 854 855 transhdrlen = 0; 856 exthdrlen = 0; 857 mtu = inet->cork.fragsize; 858 } 859 hh_len = LL_RESERVED_SPACE(rt->dst.dev); 860 861 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0); 862 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen; 863 864 if (inet->cork.length + length > 0xFFFF - fragheaderlen) { 865 ip_local_error(sk, EMSGSIZE, rt->rt_dst, inet->inet_dport, 866 mtu-exthdrlen); 867 return -EMSGSIZE; 868 } 869 870 /* 871 * transhdrlen > 0 means that this is the first fragment and we wish 872 * it won't be fragmented in the future. 873 */ 874 if (transhdrlen && 875 length + fragheaderlen <= mtu && 876 rt->dst.dev->features & NETIF_F_V4_CSUM && 877 !exthdrlen) 878 csummode = CHECKSUM_PARTIAL; 879 880 skb = skb_peek_tail(&sk->sk_write_queue); 881 882 inet->cork.length += length; 883 if (((length > mtu) || (skb && skb_is_gso(skb))) && 884 (sk->sk_protocol == IPPROTO_UDP) && 885 (rt->dst.dev->features & NETIF_F_UFO)) { 886 err = ip_ufo_append_data(sk, getfrag, from, length, hh_len, 887 fragheaderlen, transhdrlen, mtu, 888 flags); 889 if (err) 890 goto error; 891 return 0; 892 } 893 894 /* So, what's going on in the loop below? 895 * 896 * We use calculated fragment length to generate chained skb, 897 * each of segments is IP fragment ready for sending to network after 898 * adding appropriate IP header. 899 */ 900 901 if (!skb) 902 goto alloc_new_skb; 903 904 while (length > 0) { 905 /* Check if the remaining data fits into current packet. */ 906 copy = mtu - skb->len; 907 if (copy < length) 908 copy = maxfraglen - skb->len; 909 if (copy <= 0) { 910 char *data; 911 unsigned int datalen; 912 unsigned int fraglen; 913 unsigned int fraggap; 914 unsigned int alloclen; 915 struct sk_buff *skb_prev; 916 alloc_new_skb: 917 skb_prev = skb; 918 if (skb_prev) 919 fraggap = skb_prev->len - maxfraglen; 920 else 921 fraggap = 0; 922 923 /* 924 * If remaining data exceeds the mtu, 925 * we know we need more fragment(s). 926 */ 927 datalen = length + fraggap; 928 if (datalen > mtu - fragheaderlen) 929 datalen = maxfraglen - fragheaderlen; 930 fraglen = datalen + fragheaderlen; 931 932 if ((flags & MSG_MORE) && 933 !(rt->dst.dev->features&NETIF_F_SG)) 934 alloclen = mtu; 935 else 936 alloclen = fraglen; 937 938 /* The last fragment gets additional space at tail. 939 * Note, with MSG_MORE we overallocate on fragments, 940 * because we have no idea what fragment will be 941 * the last. 942 */ 943 if (datalen == length + fraggap) { 944 alloclen += rt->dst.trailer_len; 945 /* make sure mtu is not reached */ 946 if (datalen > mtu - fragheaderlen - rt->dst.trailer_len) 947 datalen -= ALIGN(rt->dst.trailer_len, 8); 948 } 949 if (transhdrlen) { 950 skb = sock_alloc_send_skb(sk, 951 alloclen + hh_len + 15, 952 (flags & MSG_DONTWAIT), &err); 953 } else { 954 skb = NULL; 955 if (atomic_read(&sk->sk_wmem_alloc) <= 956 2 * sk->sk_sndbuf) 957 skb = sock_wmalloc(sk, 958 alloclen + hh_len + 15, 1, 959 sk->sk_allocation); 960 if (unlikely(skb == NULL)) 961 err = -ENOBUFS; 962 else 963 /* only the initial fragment is 964 time stamped */ 965 ipc->tx_flags = 0; 966 } 967 if (skb == NULL) 968 goto error; 969 970 /* 971 * Fill in the control structures 972 */ 973 skb->ip_summed = csummode; 974 skb->csum = 0; 975 skb_reserve(skb, hh_len); 976 skb_shinfo(skb)->tx_flags = ipc->tx_flags; 977 978 /* 979 * Find where to start putting bytes. 980 */ 981 data = skb_put(skb, fraglen); 982 skb_set_network_header(skb, exthdrlen); 983 skb->transport_header = (skb->network_header + 984 fragheaderlen); 985 data += fragheaderlen; 986 987 if (fraggap) { 988 skb->csum = skb_copy_and_csum_bits( 989 skb_prev, maxfraglen, 990 data + transhdrlen, fraggap, 0); 991 skb_prev->csum = csum_sub(skb_prev->csum, 992 skb->csum); 993 data += fraggap; 994 pskb_trim_unique(skb_prev, maxfraglen); 995 } 996 997 copy = datalen - transhdrlen - fraggap; 998 if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) { 999 err = -EFAULT; 1000 kfree_skb(skb); 1001 goto error; 1002 } 1003 1004 offset += copy; 1005 length -= datalen - fraggap; 1006 transhdrlen = 0; 1007 exthdrlen = 0; 1008 csummode = CHECKSUM_NONE; 1009 1010 /* 1011 * Put the packet on the pending queue. 1012 */ 1013 __skb_queue_tail(&sk->sk_write_queue, skb); 1014 continue; 1015 } 1016 1017 if (copy > length) 1018 copy = length; 1019 1020 if (!(rt->dst.dev->features&NETIF_F_SG)) { 1021 unsigned int off; 1022 1023 off = skb->len; 1024 if (getfrag(from, skb_put(skb, copy), 1025 offset, copy, off, skb) < 0) { 1026 __skb_trim(skb, off); 1027 err = -EFAULT; 1028 goto error; 1029 } 1030 } else { 1031 int i = skb_shinfo(skb)->nr_frags; 1032 skb_frag_t *frag = &skb_shinfo(skb)->frags[i-1]; 1033 struct page *page = sk->sk_sndmsg_page; 1034 int off = sk->sk_sndmsg_off; 1035 unsigned int left; 1036 1037 if (page && (left = PAGE_SIZE - off) > 0) { 1038 if (copy >= left) 1039 copy = left; 1040 if (page != frag->page) { 1041 if (i == MAX_SKB_FRAGS) { 1042 err = -EMSGSIZE; 1043 goto error; 1044 } 1045 get_page(page); 1046 skb_fill_page_desc(skb, i, page, sk->sk_sndmsg_off, 0); 1047 frag = &skb_shinfo(skb)->frags[i]; 1048 } 1049 } else if (i < MAX_SKB_FRAGS) { 1050 if (copy > PAGE_SIZE) 1051 copy = PAGE_SIZE; 1052 page = alloc_pages(sk->sk_allocation, 0); 1053 if (page == NULL) { 1054 err = -ENOMEM; 1055 goto error; 1056 } 1057 sk->sk_sndmsg_page = page; 1058 sk->sk_sndmsg_off = 0; 1059 1060 skb_fill_page_desc(skb, i, page, 0, 0); 1061 frag = &skb_shinfo(skb)->frags[i]; 1062 } else { 1063 err = -EMSGSIZE; 1064 goto error; 1065 } 1066 if (getfrag(from, page_address(frag->page)+frag->page_offset+frag->size, offset, copy, skb->len, skb) < 0) { 1067 err = -EFAULT; 1068 goto error; 1069 } 1070 sk->sk_sndmsg_off += copy; 1071 frag->size += copy; 1072 skb->len += copy; 1073 skb->data_len += copy; 1074 skb->truesize += copy; 1075 atomic_add(copy, &sk->sk_wmem_alloc); 1076 } 1077 offset += copy; 1078 length -= copy; 1079 } 1080 1081 return 0; 1082 1083 error: 1084 inet->cork.length -= length; 1085 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS); 1086 return err; 1087 } 1088 1089 ssize_t ip_append_page(struct sock *sk, struct page *page, 1090 int offset, size_t size, int flags) 1091 { 1092 struct inet_sock *inet = inet_sk(sk); 1093 struct sk_buff *skb; 1094 struct rtable *rt; 1095 struct ip_options *opt = NULL; 1096 int hh_len; 1097 int mtu; 1098 int len; 1099 int err; 1100 unsigned int maxfraglen, fragheaderlen, fraggap; 1101 1102 if (inet->hdrincl) 1103 return -EPERM; 1104 1105 if (flags&MSG_PROBE) 1106 return 0; 1107 1108 if (skb_queue_empty(&sk->sk_write_queue)) 1109 return -EINVAL; 1110 1111 rt = (struct rtable *)inet->cork.dst; 1112 if (inet->cork.flags & IPCORK_OPT) 1113 opt = inet->cork.opt; 1114 1115 if (!(rt->dst.dev->features&NETIF_F_SG)) 1116 return -EOPNOTSUPP; 1117 1118 hh_len = LL_RESERVED_SPACE(rt->dst.dev); 1119 mtu = inet->cork.fragsize; 1120 1121 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0); 1122 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen; 1123 1124 if (inet->cork.length + size > 0xFFFF - fragheaderlen) { 1125 ip_local_error(sk, EMSGSIZE, rt->rt_dst, inet->inet_dport, mtu); 1126 return -EMSGSIZE; 1127 } 1128 1129 if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL) 1130 return -EINVAL; 1131 1132 inet->cork.length += size; 1133 if ((size + skb->len > mtu) && 1134 (sk->sk_protocol == IPPROTO_UDP) && 1135 (rt->dst.dev->features & NETIF_F_UFO)) { 1136 skb_shinfo(skb)->gso_size = mtu - fragheaderlen; 1137 skb_shinfo(skb)->gso_type = SKB_GSO_UDP; 1138 } 1139 1140 1141 while (size > 0) { 1142 int i; 1143 1144 if (skb_is_gso(skb)) 1145 len = size; 1146 else { 1147 1148 /* Check if the remaining data fits into current packet. */ 1149 len = mtu - skb->len; 1150 if (len < size) 1151 len = maxfraglen - skb->len; 1152 } 1153 if (len <= 0) { 1154 struct sk_buff *skb_prev; 1155 int alloclen; 1156 1157 skb_prev = skb; 1158 fraggap = skb_prev->len - maxfraglen; 1159 1160 alloclen = fragheaderlen + hh_len + fraggap + 15; 1161 skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation); 1162 if (unlikely(!skb)) { 1163 err = -ENOBUFS; 1164 goto error; 1165 } 1166 1167 /* 1168 * Fill in the control structures 1169 */ 1170 skb->ip_summed = CHECKSUM_NONE; 1171 skb->csum = 0; 1172 skb_reserve(skb, hh_len); 1173 1174 /* 1175 * Find where to start putting bytes. 1176 */ 1177 skb_put(skb, fragheaderlen + fraggap); 1178 skb_reset_network_header(skb); 1179 skb->transport_header = (skb->network_header + 1180 fragheaderlen); 1181 if (fraggap) { 1182 skb->csum = skb_copy_and_csum_bits(skb_prev, 1183 maxfraglen, 1184 skb_transport_header(skb), 1185 fraggap, 0); 1186 skb_prev->csum = csum_sub(skb_prev->csum, 1187 skb->csum); 1188 pskb_trim_unique(skb_prev, maxfraglen); 1189 } 1190 1191 /* 1192 * Put the packet on the pending queue. 1193 */ 1194 __skb_queue_tail(&sk->sk_write_queue, skb); 1195 continue; 1196 } 1197 1198 i = skb_shinfo(skb)->nr_frags; 1199 if (len > size) 1200 len = size; 1201 if (skb_can_coalesce(skb, i, page, offset)) { 1202 skb_shinfo(skb)->frags[i-1].size += len; 1203 } else if (i < MAX_SKB_FRAGS) { 1204 get_page(page); 1205 skb_fill_page_desc(skb, i, page, offset, len); 1206 } else { 1207 err = -EMSGSIZE; 1208 goto error; 1209 } 1210 1211 if (skb->ip_summed == CHECKSUM_NONE) { 1212 __wsum csum; 1213 csum = csum_page(page, offset, len); 1214 skb->csum = csum_block_add(skb->csum, csum, skb->len); 1215 } 1216 1217 skb->len += len; 1218 skb->data_len += len; 1219 skb->truesize += len; 1220 atomic_add(len, &sk->sk_wmem_alloc); 1221 offset += len; 1222 size -= len; 1223 } 1224 return 0; 1225 1226 error: 1227 inet->cork.length -= size; 1228 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS); 1229 return err; 1230 } 1231 1232 static void ip_cork_release(struct inet_sock *inet) 1233 { 1234 inet->cork.flags &= ~IPCORK_OPT; 1235 kfree(inet->cork.opt); 1236 inet->cork.opt = NULL; 1237 dst_release(inet->cork.dst); 1238 inet->cork.dst = NULL; 1239 } 1240 1241 /* 1242 * Combined all pending IP fragments on the socket as one IP datagram 1243 * and push them out. 1244 */ 1245 int ip_push_pending_frames(struct sock *sk) 1246 { 1247 struct sk_buff *skb, *tmp_skb; 1248 struct sk_buff **tail_skb; 1249 struct inet_sock *inet = inet_sk(sk); 1250 struct net *net = sock_net(sk); 1251 struct ip_options *opt = NULL; 1252 struct rtable *rt = (struct rtable *)inet->cork.dst; 1253 struct iphdr *iph; 1254 __be16 df = 0; 1255 __u8 ttl; 1256 int err = 0; 1257 1258 if ((skb = __skb_dequeue(&sk->sk_write_queue)) == NULL) 1259 goto out; 1260 tail_skb = &(skb_shinfo(skb)->frag_list); 1261 1262 /* move skb->data to ip header from ext header */ 1263 if (skb->data < skb_network_header(skb)) 1264 __skb_pull(skb, skb_network_offset(skb)); 1265 while ((tmp_skb = __skb_dequeue(&sk->sk_write_queue)) != NULL) { 1266 __skb_pull(tmp_skb, skb_network_header_len(skb)); 1267 *tail_skb = tmp_skb; 1268 tail_skb = &(tmp_skb->next); 1269 skb->len += tmp_skb->len; 1270 skb->data_len += tmp_skb->len; 1271 skb->truesize += tmp_skb->truesize; 1272 tmp_skb->destructor = NULL; 1273 tmp_skb->sk = NULL; 1274 } 1275 1276 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow 1277 * to fragment the frame generated here. No matter, what transforms 1278 * how transforms change size of the packet, it will come out. 1279 */ 1280 if (inet->pmtudisc < IP_PMTUDISC_DO) 1281 skb->local_df = 1; 1282 1283 /* DF bit is set when we want to see DF on outgoing frames. 1284 * If local_df is set too, we still allow to fragment this frame 1285 * locally. */ 1286 if (inet->pmtudisc >= IP_PMTUDISC_DO || 1287 (skb->len <= dst_mtu(&rt->dst) && 1288 ip_dont_fragment(sk, &rt->dst))) 1289 df = htons(IP_DF); 1290 1291 if (inet->cork.flags & IPCORK_OPT) 1292 opt = inet->cork.opt; 1293 1294 if (rt->rt_type == RTN_MULTICAST) 1295 ttl = inet->mc_ttl; 1296 else 1297 ttl = ip_select_ttl(inet, &rt->dst); 1298 1299 iph = (struct iphdr *)skb->data; 1300 iph->version = 4; 1301 iph->ihl = 5; 1302 if (opt) { 1303 iph->ihl += opt->optlen>>2; 1304 ip_options_build(skb, opt, inet->cork.addr, rt, 0); 1305 } 1306 iph->tos = inet->tos; 1307 iph->frag_off = df; 1308 ip_select_ident(iph, &rt->dst, sk); 1309 iph->ttl = ttl; 1310 iph->protocol = sk->sk_protocol; 1311 iph->saddr = rt->rt_src; 1312 iph->daddr = rt->rt_dst; 1313 1314 skb->priority = sk->sk_priority; 1315 skb->mark = sk->sk_mark; 1316 /* 1317 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec 1318 * on dst refcount 1319 */ 1320 inet->cork.dst = NULL; 1321 skb_dst_set(skb, &rt->dst); 1322 1323 if (iph->protocol == IPPROTO_ICMP) 1324 icmp_out_count(net, ((struct icmphdr *) 1325 skb_transport_header(skb))->type); 1326 1327 /* Netfilter gets whole the not fragmented skb. */ 1328 err = ip_local_out(skb); 1329 if (err) { 1330 if (err > 0) 1331 err = net_xmit_errno(err); 1332 if (err) 1333 goto error; 1334 } 1335 1336 out: 1337 ip_cork_release(inet); 1338 return err; 1339 1340 error: 1341 IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS); 1342 goto out; 1343 } 1344 1345 /* 1346 * Throw away all pending data on the socket. 1347 */ 1348 void ip_flush_pending_frames(struct sock *sk) 1349 { 1350 struct sk_buff *skb; 1351 1352 while ((skb = __skb_dequeue_tail(&sk->sk_write_queue)) != NULL) 1353 kfree_skb(skb); 1354 1355 ip_cork_release(inet_sk(sk)); 1356 } 1357 1358 1359 /* 1360 * Fetch data from kernel space and fill in checksum if needed. 1361 */ 1362 static int ip_reply_glue_bits(void *dptr, char *to, int offset, 1363 int len, int odd, struct sk_buff *skb) 1364 { 1365 __wsum csum; 1366 1367 csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0); 1368 skb->csum = csum_block_add(skb->csum, csum, odd); 1369 return 0; 1370 } 1371 1372 /* 1373 * Generic function to send a packet as reply to another packet. 1374 * Used to send TCP resets so far. ICMP should use this function too. 1375 * 1376 * Should run single threaded per socket because it uses the sock 1377 * structure to pass arguments. 1378 */ 1379 void ip_send_reply(struct sock *sk, struct sk_buff *skb, struct ip_reply_arg *arg, 1380 unsigned int len) 1381 { 1382 struct inet_sock *inet = inet_sk(sk); 1383 struct { 1384 struct ip_options opt; 1385 char data[40]; 1386 } replyopts; 1387 struct ipcm_cookie ipc; 1388 __be32 daddr; 1389 struct rtable *rt = skb_rtable(skb); 1390 1391 if (ip_options_echo(&replyopts.opt, skb)) 1392 return; 1393 1394 daddr = ipc.addr = rt->rt_src; 1395 ipc.opt = NULL; 1396 ipc.tx_flags = 0; 1397 1398 if (replyopts.opt.optlen) { 1399 ipc.opt = &replyopts.opt; 1400 1401 if (ipc.opt->srr) 1402 daddr = replyopts.opt.faddr; 1403 } 1404 1405 { 1406 struct flowi fl = { .oif = arg->bound_dev_if, 1407 .nl_u = { .ip4_u = 1408 { .daddr = daddr, 1409 .saddr = rt->rt_spec_dst, 1410 .tos = RT_TOS(ip_hdr(skb)->tos) } }, 1411 /* Not quite clean, but right. */ 1412 .uli_u = { .ports = 1413 { .sport = tcp_hdr(skb)->dest, 1414 .dport = tcp_hdr(skb)->source } }, 1415 .proto = sk->sk_protocol, 1416 .flags = ip_reply_arg_flowi_flags(arg) }; 1417 security_skb_classify_flow(skb, &fl); 1418 if (ip_route_output_key(sock_net(sk), &rt, &fl)) 1419 return; 1420 } 1421 1422 /* And let IP do all the hard work. 1423 1424 This chunk is not reenterable, hence spinlock. 1425 Note that it uses the fact, that this function is called 1426 with locally disabled BH and that sk cannot be already spinlocked. 1427 */ 1428 bh_lock_sock(sk); 1429 inet->tos = ip_hdr(skb)->tos; 1430 sk->sk_priority = skb->priority; 1431 sk->sk_protocol = ip_hdr(skb)->protocol; 1432 sk->sk_bound_dev_if = arg->bound_dev_if; 1433 ip_append_data(sk, ip_reply_glue_bits, arg->iov->iov_base, len, 0, 1434 &ipc, &rt, MSG_DONTWAIT); 1435 if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) { 1436 if (arg->csumoffset >= 0) 1437 *((__sum16 *)skb_transport_header(skb) + 1438 arg->csumoffset) = csum_fold(csum_add(skb->csum, 1439 arg->csum)); 1440 skb->ip_summed = CHECKSUM_NONE; 1441 ip_push_pending_frames(sk); 1442 } 1443 1444 bh_unlock_sock(sk); 1445 1446 ip_rt_put(rt); 1447 } 1448 1449 void __init ip_init(void) 1450 { 1451 ip_rt_init(); 1452 inet_initpeers(); 1453 1454 #if defined(CONFIG_IP_MULTICAST) && defined(CONFIG_PROC_FS) 1455 igmp_mc_proc_init(); 1456 #endif 1457 } 1458