ip_output.c revision f6d8bd051c391c1c0458a30b2a7abcd939329259
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 84int sysctl_ip_default_ttl __read_mostly = IPDEFTTL; 85EXPORT_SYMBOL(sysctl_ip_default_ttl); 86 87/* Generate a checksum for an outgoing IP datagram. */ 88__inline__ void ip_send_check(struct iphdr *iph) 89{ 90 iph->check = 0; 91 iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl); 92} 93EXPORT_SYMBOL(ip_send_check); 94 95int __ip_local_out(struct sk_buff *skb) 96{ 97 struct iphdr *iph = ip_hdr(skb); 98 99 iph->tot_len = htons(skb->len); 100 ip_send_check(iph); 101 return nf_hook(NFPROTO_IPV4, NF_INET_LOCAL_OUT, skb, NULL, 102 skb_dst(skb)->dev, dst_output); 103} 104 105int ip_local_out(struct sk_buff *skb) 106{ 107 int err; 108 109 err = __ip_local_out(skb); 110 if (likely(err == 1)) 111 err = dst_output(skb); 112 113 return err; 114} 115EXPORT_SYMBOL_GPL(ip_local_out); 116 117/* dev_loopback_xmit for use with netfilter. */ 118static int ip_dev_loopback_xmit(struct sk_buff *newskb) 119{ 120 skb_reset_mac_header(newskb); 121 __skb_pull(newskb, skb_network_offset(newskb)); 122 newskb->pkt_type = PACKET_LOOPBACK; 123 newskb->ip_summed = CHECKSUM_UNNECESSARY; 124 WARN_ON(!skb_dst(newskb)); 125 netif_rx_ni(newskb); 126 return 0; 127} 128 129static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst) 130{ 131 int ttl = inet->uc_ttl; 132 133 if (ttl < 0) 134 ttl = ip4_dst_hoplimit(dst); 135 return ttl; 136} 137 138/* 139 * Add an ip header to a skbuff and send it out. 140 * 141 */ 142int ip_build_and_send_pkt(struct sk_buff *skb, struct sock *sk, 143 __be32 saddr, __be32 daddr, struct ip_options_rcu *opt) 144{ 145 struct inet_sock *inet = inet_sk(sk); 146 struct rtable *rt = skb_rtable(skb); 147 struct iphdr *iph; 148 149 /* Build the IP header. */ 150 skb_push(skb, sizeof(struct iphdr) + (opt ? opt->opt.optlen : 0)); 151 skb_reset_network_header(skb); 152 iph = ip_hdr(skb); 153 iph->version = 4; 154 iph->ihl = 5; 155 iph->tos = inet->tos; 156 if (ip_dont_fragment(sk, &rt->dst)) 157 iph->frag_off = htons(IP_DF); 158 else 159 iph->frag_off = 0; 160 iph->ttl = ip_select_ttl(inet, &rt->dst); 161 iph->daddr = rt->rt_dst; 162 iph->saddr = rt->rt_src; 163 iph->protocol = sk->sk_protocol; 164 ip_select_ident(iph, &rt->dst, sk); 165 166 if (opt && opt->opt.optlen) { 167 iph->ihl += opt->opt.optlen>>2; 168 ip_options_build(skb, &opt->opt, daddr, rt, 0); 169 } 170 171 skb->priority = sk->sk_priority; 172 skb->mark = sk->sk_mark; 173 174 /* Send it out. */ 175 return ip_local_out(skb); 176} 177EXPORT_SYMBOL_GPL(ip_build_and_send_pkt); 178 179static inline int ip_finish_output2(struct sk_buff *skb) 180{ 181 struct dst_entry *dst = skb_dst(skb); 182 struct rtable *rt = (struct rtable *)dst; 183 struct net_device *dev = dst->dev; 184 unsigned int hh_len = LL_RESERVED_SPACE(dev); 185 186 if (rt->rt_type == RTN_MULTICAST) { 187 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUTMCAST, skb->len); 188 } else if (rt->rt_type == RTN_BROADCAST) 189 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUTBCAST, skb->len); 190 191 /* Be paranoid, rather than too clever. */ 192 if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) { 193 struct sk_buff *skb2; 194 195 skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev)); 196 if (skb2 == NULL) { 197 kfree_skb(skb); 198 return -ENOMEM; 199 } 200 if (skb->sk) 201 skb_set_owner_w(skb2, skb->sk); 202 kfree_skb(skb); 203 skb = skb2; 204 } 205 206 if (dst->hh) 207 return neigh_hh_output(dst->hh, skb); 208 else if (dst->neighbour) 209 return dst->neighbour->output(skb); 210 211 if (net_ratelimit()) 212 printk(KERN_DEBUG "ip_finish_output2: No header cache and no neighbour!\n"); 213 kfree_skb(skb); 214 return -EINVAL; 215} 216 217static inline int ip_skb_dst_mtu(struct sk_buff *skb) 218{ 219 struct inet_sock *inet = skb->sk ? inet_sk(skb->sk) : NULL; 220 221 return (inet && inet->pmtudisc == IP_PMTUDISC_PROBE) ? 222 skb_dst(skb)->dev->mtu : dst_mtu(skb_dst(skb)); 223} 224 225static int ip_finish_output(struct sk_buff *skb) 226{ 227#if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM) 228 /* Policy lookup after SNAT yielded a new policy */ 229 if (skb_dst(skb)->xfrm != NULL) { 230 IPCB(skb)->flags |= IPSKB_REROUTED; 231 return dst_output(skb); 232 } 233#endif 234 if (skb->len > ip_skb_dst_mtu(skb) && !skb_is_gso(skb)) 235 return ip_fragment(skb, ip_finish_output2); 236 else 237 return ip_finish_output2(skb); 238} 239 240int ip_mc_output(struct sk_buff *skb) 241{ 242 struct sock *sk = skb->sk; 243 struct rtable *rt = skb_rtable(skb); 244 struct net_device *dev = rt->dst.dev; 245 246 /* 247 * If the indicated interface is up and running, send the packet. 248 */ 249 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len); 250 251 skb->dev = dev; 252 skb->protocol = htons(ETH_P_IP); 253 254 /* 255 * Multicasts are looped back for other local users 256 */ 257 258 if (rt->rt_flags&RTCF_MULTICAST) { 259 if (sk_mc_loop(sk) 260#ifdef CONFIG_IP_MROUTE 261 /* Small optimization: do not loopback not local frames, 262 which returned after forwarding; they will be dropped 263 by ip_mr_input in any case. 264 Note, that local frames are looped back to be delivered 265 to local recipients. 266 267 This check is duplicated in ip_mr_input at the moment. 268 */ 269 && 270 ((rt->rt_flags & RTCF_LOCAL) || 271 !(IPCB(skb)->flags & IPSKB_FORWARDED)) 272#endif 273 ) { 274 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC); 275 if (newskb) 276 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, 277 newskb, NULL, newskb->dev, 278 ip_dev_loopback_xmit); 279 } 280 281 /* Multicasts with ttl 0 must not go beyond the host */ 282 283 if (ip_hdr(skb)->ttl == 0) { 284 kfree_skb(skb); 285 return 0; 286 } 287 } 288 289 if (rt->rt_flags&RTCF_BROADCAST) { 290 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC); 291 if (newskb) 292 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, newskb, 293 NULL, newskb->dev, ip_dev_loopback_xmit); 294 } 295 296 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb, NULL, 297 skb->dev, ip_finish_output, 298 !(IPCB(skb)->flags & IPSKB_REROUTED)); 299} 300 301int ip_output(struct sk_buff *skb) 302{ 303 struct net_device *dev = skb_dst(skb)->dev; 304 305 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len); 306 307 skb->dev = dev; 308 skb->protocol = htons(ETH_P_IP); 309 310 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb, NULL, dev, 311 ip_finish_output, 312 !(IPCB(skb)->flags & IPSKB_REROUTED)); 313} 314 315int ip_queue_xmit(struct sk_buff *skb) 316{ 317 struct sock *sk = skb->sk; 318 struct inet_sock *inet = inet_sk(sk); 319 struct ip_options_rcu *inet_opt; 320 struct rtable *rt; 321 struct iphdr *iph; 322 int res; 323 324 /* Skip all of this if the packet is already routed, 325 * f.e. by something like SCTP. 326 */ 327 rcu_read_lock(); 328 inet_opt = rcu_dereference(inet->inet_opt); 329 rt = skb_rtable(skb); 330 if (rt != NULL) 331 goto packet_routed; 332 333 /* Make sure we can route this packet. */ 334 rt = (struct rtable *)__sk_dst_check(sk, 0); 335 if (rt == NULL) { 336 __be32 daddr; 337 338 /* Use correct destination address if we have options. */ 339 daddr = inet->inet_daddr; 340 if (inet_opt && inet_opt->opt.srr) 341 daddr = inet_opt->opt.faddr; 342 343 /* If this fails, retransmit mechanism of transport layer will 344 * keep trying until route appears or the connection times 345 * itself out. 346 */ 347 rt = ip_route_output_ports(sock_net(sk), sk, 348 daddr, inet->inet_saddr, 349 inet->inet_dport, 350 inet->inet_sport, 351 sk->sk_protocol, 352 RT_CONN_FLAGS(sk), 353 sk->sk_bound_dev_if); 354 if (IS_ERR(rt)) 355 goto no_route; 356 sk_setup_caps(sk, &rt->dst); 357 } 358 skb_dst_set_noref(skb, &rt->dst); 359 360packet_routed: 361 if (inet_opt && inet_opt->opt.is_strictroute && rt->rt_dst != rt->rt_gateway) 362 goto no_route; 363 364 /* OK, we know where to send it, allocate and build IP header. */ 365 skb_push(skb, sizeof(struct iphdr) + (inet_opt ? inet_opt->opt.optlen : 0)); 366 skb_reset_network_header(skb); 367 iph = ip_hdr(skb); 368 *((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (inet->tos & 0xff)); 369 if (ip_dont_fragment(sk, &rt->dst) && !skb->local_df) 370 iph->frag_off = htons(IP_DF); 371 else 372 iph->frag_off = 0; 373 iph->ttl = ip_select_ttl(inet, &rt->dst); 374 iph->protocol = sk->sk_protocol; 375 iph->saddr = rt->rt_src; 376 iph->daddr = rt->rt_dst; 377 /* Transport layer set skb->h.foo itself. */ 378 379 if (inet_opt && inet_opt->opt.optlen) { 380 iph->ihl += inet_opt->opt.optlen >> 2; 381 ip_options_build(skb, &inet_opt->opt, inet->inet_daddr, rt, 0); 382 } 383 384 ip_select_ident_more(iph, &rt->dst, sk, 385 (skb_shinfo(skb)->gso_segs ?: 1) - 1); 386 387 skb->priority = sk->sk_priority; 388 skb->mark = sk->sk_mark; 389 390 res = ip_local_out(skb); 391 rcu_read_unlock(); 392 return res; 393 394no_route: 395 rcu_read_unlock(); 396 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES); 397 kfree_skb(skb); 398 return -EHOSTUNREACH; 399} 400EXPORT_SYMBOL(ip_queue_xmit); 401 402 403static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from) 404{ 405 to->pkt_type = from->pkt_type; 406 to->priority = from->priority; 407 to->protocol = from->protocol; 408 skb_dst_drop(to); 409 skb_dst_copy(to, from); 410 to->dev = from->dev; 411 to->mark = from->mark; 412 413 /* Copy the flags to each fragment. */ 414 IPCB(to)->flags = IPCB(from)->flags; 415 416#ifdef CONFIG_NET_SCHED 417 to->tc_index = from->tc_index; 418#endif 419 nf_copy(to, from); 420#if defined(CONFIG_NETFILTER_XT_TARGET_TRACE) || \ 421 defined(CONFIG_NETFILTER_XT_TARGET_TRACE_MODULE) 422 to->nf_trace = from->nf_trace; 423#endif 424#if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE) 425 to->ipvs_property = from->ipvs_property; 426#endif 427 skb_copy_secmark(to, from); 428} 429 430/* 431 * This IP datagram is too large to be sent in one piece. Break it up into 432 * smaller pieces (each of size equal to IP header plus 433 * a block of the data of the original IP data part) that will yet fit in a 434 * single device frame, and queue such a frame for sending. 435 */ 436 437int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *)) 438{ 439 struct iphdr *iph; 440 int ptr; 441 struct net_device *dev; 442 struct sk_buff *skb2; 443 unsigned int mtu, hlen, left, len, ll_rs; 444 int offset; 445 __be16 not_last_frag; 446 struct rtable *rt = skb_rtable(skb); 447 int err = 0; 448 449 dev = rt->dst.dev; 450 451 /* 452 * Point into the IP datagram header. 453 */ 454 455 iph = ip_hdr(skb); 456 457 if (unlikely((iph->frag_off & htons(IP_DF)) && !skb->local_df)) { 458 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); 459 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, 460 htonl(ip_skb_dst_mtu(skb))); 461 kfree_skb(skb); 462 return -EMSGSIZE; 463 } 464 465 /* 466 * Setup starting values. 467 */ 468 469 hlen = iph->ihl * 4; 470 mtu = dst_mtu(&rt->dst) - hlen; /* Size of data space */ 471#ifdef CONFIG_BRIDGE_NETFILTER 472 if (skb->nf_bridge) 473 mtu -= nf_bridge_mtu_reduction(skb); 474#endif 475 IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE; 476 477 /* When frag_list is given, use it. First, check its validity: 478 * some transformers could create wrong frag_list or break existing 479 * one, it is not prohibited. In this case fall back to copying. 480 * 481 * LATER: this step can be merged to real generation of fragments, 482 * we can switch to copy when see the first bad fragment. 483 */ 484 if (skb_has_frag_list(skb)) { 485 struct sk_buff *frag, *frag2; 486 int first_len = skb_pagelen(skb); 487 488 if (first_len - hlen > mtu || 489 ((first_len - hlen) & 7) || 490 (iph->frag_off & htons(IP_MF|IP_OFFSET)) || 491 skb_cloned(skb)) 492 goto slow_path; 493 494 skb_walk_frags(skb, frag) { 495 /* Correct geometry. */ 496 if (frag->len > mtu || 497 ((frag->len & 7) && frag->next) || 498 skb_headroom(frag) < hlen) 499 goto slow_path_clean; 500 501 /* Partially cloned skb? */ 502 if (skb_shared(frag)) 503 goto slow_path_clean; 504 505 BUG_ON(frag->sk); 506 if (skb->sk) { 507 frag->sk = skb->sk; 508 frag->destructor = sock_wfree; 509 } 510 skb->truesize -= frag->truesize; 511 } 512 513 /* Everything is OK. Generate! */ 514 515 err = 0; 516 offset = 0; 517 frag = skb_shinfo(skb)->frag_list; 518 skb_frag_list_init(skb); 519 skb->data_len = first_len - skb_headlen(skb); 520 skb->len = first_len; 521 iph->tot_len = htons(first_len); 522 iph->frag_off = htons(IP_MF); 523 ip_send_check(iph); 524 525 for (;;) { 526 /* Prepare header of the next frame, 527 * before previous one went down. */ 528 if (frag) { 529 frag->ip_summed = CHECKSUM_NONE; 530 skb_reset_transport_header(frag); 531 __skb_push(frag, hlen); 532 skb_reset_network_header(frag); 533 memcpy(skb_network_header(frag), iph, hlen); 534 iph = ip_hdr(frag); 535 iph->tot_len = htons(frag->len); 536 ip_copy_metadata(frag, skb); 537 if (offset == 0) 538 ip_options_fragment(frag); 539 offset += skb->len - hlen; 540 iph->frag_off = htons(offset>>3); 541 if (frag->next != NULL) 542 iph->frag_off |= htons(IP_MF); 543 /* Ready, complete checksum */ 544 ip_send_check(iph); 545 } 546 547 err = output(skb); 548 549 if (!err) 550 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES); 551 if (err || !frag) 552 break; 553 554 skb = frag; 555 frag = skb->next; 556 skb->next = NULL; 557 } 558 559 if (err == 0) { 560 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS); 561 return 0; 562 } 563 564 while (frag) { 565 skb = frag->next; 566 kfree_skb(frag); 567 frag = skb; 568 } 569 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); 570 return err; 571 572slow_path_clean: 573 skb_walk_frags(skb, frag2) { 574 if (frag2 == frag) 575 break; 576 frag2->sk = NULL; 577 frag2->destructor = NULL; 578 skb->truesize += frag2->truesize; 579 } 580 } 581 582slow_path: 583 left = skb->len - hlen; /* Space per frame */ 584 ptr = hlen; /* Where to start from */ 585 586 /* for bridged IP traffic encapsulated inside f.e. a vlan header, 587 * we need to make room for the encapsulating header 588 */ 589 ll_rs = LL_RESERVED_SPACE_EXTRA(rt->dst.dev, nf_bridge_pad(skb)); 590 591 /* 592 * Fragment the datagram. 593 */ 594 595 offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3; 596 not_last_frag = iph->frag_off & htons(IP_MF); 597 598 /* 599 * Keep copying data until we run out. 600 */ 601 602 while (left > 0) { 603 len = left; 604 /* IF: it doesn't fit, use 'mtu' - the data space left */ 605 if (len > mtu) 606 len = mtu; 607 /* IF: we are not sending up to and including the packet end 608 then align the next start on an eight byte boundary */ 609 if (len < left) { 610 len &= ~7; 611 } 612 /* 613 * Allocate buffer. 614 */ 615 616 if ((skb2 = alloc_skb(len+hlen+ll_rs, GFP_ATOMIC)) == NULL) { 617 NETDEBUG(KERN_INFO "IP: frag: no memory for new fragment!\n"); 618 err = -ENOMEM; 619 goto fail; 620 } 621 622 /* 623 * Set up data on packet 624 */ 625 626 ip_copy_metadata(skb2, skb); 627 skb_reserve(skb2, ll_rs); 628 skb_put(skb2, len + hlen); 629 skb_reset_network_header(skb2); 630 skb2->transport_header = skb2->network_header + hlen; 631 632 /* 633 * Charge the memory for the fragment to any owner 634 * it might possess 635 */ 636 637 if (skb->sk) 638 skb_set_owner_w(skb2, skb->sk); 639 640 /* 641 * Copy the packet header into the new buffer. 642 */ 643 644 skb_copy_from_linear_data(skb, skb_network_header(skb2), hlen); 645 646 /* 647 * Copy a block of the IP datagram. 648 */ 649 if (skb_copy_bits(skb, ptr, skb_transport_header(skb2), len)) 650 BUG(); 651 left -= len; 652 653 /* 654 * Fill in the new header fields. 655 */ 656 iph = ip_hdr(skb2); 657 iph->frag_off = htons((offset >> 3)); 658 659 /* ANK: dirty, but effective trick. Upgrade options only if 660 * the segment to be fragmented was THE FIRST (otherwise, 661 * options are already fixed) and make it ONCE 662 * on the initial skb, so that all the following fragments 663 * will inherit fixed options. 664 */ 665 if (offset == 0) 666 ip_options_fragment(skb); 667 668 /* 669 * Added AC : If we are fragmenting a fragment that's not the 670 * last fragment then keep MF on each bit 671 */ 672 if (left > 0 || not_last_frag) 673 iph->frag_off |= htons(IP_MF); 674 ptr += len; 675 offset += len; 676 677 /* 678 * Put this fragment into the sending queue. 679 */ 680 iph->tot_len = htons(len + hlen); 681 682 ip_send_check(iph); 683 684 err = output(skb2); 685 if (err) 686 goto fail; 687 688 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES); 689 } 690 kfree_skb(skb); 691 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS); 692 return err; 693 694fail: 695 kfree_skb(skb); 696 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); 697 return err; 698} 699EXPORT_SYMBOL(ip_fragment); 700 701int 702ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb) 703{ 704 struct iovec *iov = from; 705 706 if (skb->ip_summed == CHECKSUM_PARTIAL) { 707 if (memcpy_fromiovecend(to, iov, offset, len) < 0) 708 return -EFAULT; 709 } else { 710 __wsum csum = 0; 711 if (csum_partial_copy_fromiovecend(to, iov, offset, len, &csum) < 0) 712 return -EFAULT; 713 skb->csum = csum_block_add(skb->csum, csum, odd); 714 } 715 return 0; 716} 717EXPORT_SYMBOL(ip_generic_getfrag); 718 719static inline __wsum 720csum_page(struct page *page, int offset, int copy) 721{ 722 char *kaddr; 723 __wsum csum; 724 kaddr = kmap(page); 725 csum = csum_partial(kaddr + offset, copy, 0); 726 kunmap(page); 727 return csum; 728} 729 730static inline int ip_ufo_append_data(struct sock *sk, 731 struct sk_buff_head *queue, 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(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; 766 767 /* specify the length of each IP datagram fragment */ 768 skb_shinfo(skb)->gso_size = mtu - fragheaderlen; 769 skb_shinfo(skb)->gso_type = SKB_GSO_UDP; 770 __skb_queue_tail(queue, skb); 771 } 772 773 return skb_append_datato_frags(sk, skb, getfrag, from, 774 (length - transhdrlen)); 775} 776 777static int __ip_append_data(struct sock *sk, struct sk_buff_head *queue, 778 struct inet_cork *cork, 779 int getfrag(void *from, char *to, int offset, 780 int len, int odd, struct sk_buff *skb), 781 void *from, int length, int transhdrlen, 782 unsigned int flags) 783{ 784 struct inet_sock *inet = inet_sk(sk); 785 struct sk_buff *skb; 786 787 struct ip_options *opt = cork->opt; 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 = (struct rtable *)cork->dst; 797 798 exthdrlen = transhdrlen ? rt->dst.header_len : 0; 799 length += exthdrlen; 800 transhdrlen += exthdrlen; 801 mtu = cork->fragsize; 802 803 hh_len = LL_RESERVED_SPACE(rt->dst.dev); 804 805 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0); 806 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen; 807 808 if (cork->length + length > 0xFFFF - fragheaderlen) { 809 ip_local_error(sk, EMSGSIZE, rt->rt_dst, inet->inet_dport, 810 mtu-exthdrlen); 811 return -EMSGSIZE; 812 } 813 814 /* 815 * transhdrlen > 0 means that this is the first fragment and we wish 816 * it won't be fragmented in the future. 817 */ 818 if (transhdrlen && 819 length + fragheaderlen <= mtu && 820 rt->dst.dev->features & NETIF_F_V4_CSUM && 821 !exthdrlen) 822 csummode = CHECKSUM_PARTIAL; 823 824 skb = skb_peek_tail(queue); 825 826 cork->length += length; 827 if (((length > mtu) || (skb && skb_is_gso(skb))) && 828 (sk->sk_protocol == IPPROTO_UDP) && 829 (rt->dst.dev->features & NETIF_F_UFO)) { 830 err = ip_ufo_append_data(sk, queue, getfrag, from, length, 831 hh_len, fragheaderlen, transhdrlen, 832 mtu, flags); 833 if (err) 834 goto error; 835 return 0; 836 } 837 838 /* So, what's going on in the loop below? 839 * 840 * We use calculated fragment length to generate chained skb, 841 * each of segments is IP fragment ready for sending to network after 842 * adding appropriate IP header. 843 */ 844 845 if (!skb) 846 goto alloc_new_skb; 847 848 while (length > 0) { 849 /* Check if the remaining data fits into current packet. */ 850 copy = mtu - skb->len; 851 if (copy < length) 852 copy = maxfraglen - skb->len; 853 if (copy <= 0) { 854 char *data; 855 unsigned int datalen; 856 unsigned int fraglen; 857 unsigned int fraggap; 858 unsigned int alloclen; 859 struct sk_buff *skb_prev; 860alloc_new_skb: 861 skb_prev = skb; 862 if (skb_prev) 863 fraggap = skb_prev->len - maxfraglen; 864 else 865 fraggap = 0; 866 867 /* 868 * If remaining data exceeds the mtu, 869 * we know we need more fragment(s). 870 */ 871 datalen = length + fraggap; 872 if (datalen > mtu - fragheaderlen) 873 datalen = maxfraglen - fragheaderlen; 874 fraglen = datalen + fragheaderlen; 875 876 if ((flags & MSG_MORE) && 877 !(rt->dst.dev->features&NETIF_F_SG)) 878 alloclen = mtu; 879 else 880 alloclen = fraglen; 881 882 /* The last fragment gets additional space at tail. 883 * Note, with MSG_MORE we overallocate on fragments, 884 * because we have no idea what fragment will be 885 * the last. 886 */ 887 if (datalen == length + fraggap) { 888 alloclen += rt->dst.trailer_len; 889 /* make sure mtu is not reached */ 890 if (datalen > mtu - fragheaderlen - rt->dst.trailer_len) 891 datalen -= ALIGN(rt->dst.trailer_len, 8); 892 } 893 if (transhdrlen) { 894 skb = sock_alloc_send_skb(sk, 895 alloclen + hh_len + 15, 896 (flags & MSG_DONTWAIT), &err); 897 } else { 898 skb = NULL; 899 if (atomic_read(&sk->sk_wmem_alloc) <= 900 2 * sk->sk_sndbuf) 901 skb = sock_wmalloc(sk, 902 alloclen + hh_len + 15, 1, 903 sk->sk_allocation); 904 if (unlikely(skb == NULL)) 905 err = -ENOBUFS; 906 else 907 /* only the initial fragment is 908 time stamped */ 909 cork->tx_flags = 0; 910 } 911 if (skb == NULL) 912 goto error; 913 914 /* 915 * Fill in the control structures 916 */ 917 skb->ip_summed = csummode; 918 skb->csum = 0; 919 skb_reserve(skb, hh_len); 920 skb_shinfo(skb)->tx_flags = cork->tx_flags; 921 922 /* 923 * Find where to start putting bytes. 924 */ 925 data = skb_put(skb, fraglen); 926 skb_set_network_header(skb, exthdrlen); 927 skb->transport_header = (skb->network_header + 928 fragheaderlen); 929 data += fragheaderlen; 930 931 if (fraggap) { 932 skb->csum = skb_copy_and_csum_bits( 933 skb_prev, maxfraglen, 934 data + transhdrlen, fraggap, 0); 935 skb_prev->csum = csum_sub(skb_prev->csum, 936 skb->csum); 937 data += fraggap; 938 pskb_trim_unique(skb_prev, maxfraglen); 939 } 940 941 copy = datalen - transhdrlen - fraggap; 942 if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) { 943 err = -EFAULT; 944 kfree_skb(skb); 945 goto error; 946 } 947 948 offset += copy; 949 length -= datalen - fraggap; 950 transhdrlen = 0; 951 exthdrlen = 0; 952 csummode = CHECKSUM_NONE; 953 954 /* 955 * Put the packet on the pending queue. 956 */ 957 __skb_queue_tail(queue, skb); 958 continue; 959 } 960 961 if (copy > length) 962 copy = length; 963 964 if (!(rt->dst.dev->features&NETIF_F_SG)) { 965 unsigned int off; 966 967 off = skb->len; 968 if (getfrag(from, skb_put(skb, copy), 969 offset, copy, off, skb) < 0) { 970 __skb_trim(skb, off); 971 err = -EFAULT; 972 goto error; 973 } 974 } else { 975 int i = skb_shinfo(skb)->nr_frags; 976 skb_frag_t *frag = &skb_shinfo(skb)->frags[i-1]; 977 struct page *page = cork->page; 978 int off = cork->off; 979 unsigned int left; 980 981 if (page && (left = PAGE_SIZE - off) > 0) { 982 if (copy >= left) 983 copy = left; 984 if (page != frag->page) { 985 if (i == MAX_SKB_FRAGS) { 986 err = -EMSGSIZE; 987 goto error; 988 } 989 get_page(page); 990 skb_fill_page_desc(skb, i, page, off, 0); 991 frag = &skb_shinfo(skb)->frags[i]; 992 } 993 } else if (i < MAX_SKB_FRAGS) { 994 if (copy > PAGE_SIZE) 995 copy = PAGE_SIZE; 996 page = alloc_pages(sk->sk_allocation, 0); 997 if (page == NULL) { 998 err = -ENOMEM; 999 goto error; 1000 } 1001 cork->page = page; 1002 cork->off = 0; 1003 1004 skb_fill_page_desc(skb, i, page, 0, 0); 1005 frag = &skb_shinfo(skb)->frags[i]; 1006 } else { 1007 err = -EMSGSIZE; 1008 goto error; 1009 } 1010 if (getfrag(from, page_address(frag->page)+frag->page_offset+frag->size, offset, copy, skb->len, skb) < 0) { 1011 err = -EFAULT; 1012 goto error; 1013 } 1014 cork->off += copy; 1015 frag->size += copy; 1016 skb->len += copy; 1017 skb->data_len += copy; 1018 skb->truesize += copy; 1019 atomic_add(copy, &sk->sk_wmem_alloc); 1020 } 1021 offset += copy; 1022 length -= copy; 1023 } 1024 1025 return 0; 1026 1027error: 1028 cork->length -= length; 1029 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS); 1030 return err; 1031} 1032 1033static int ip_setup_cork(struct sock *sk, struct inet_cork *cork, 1034 struct ipcm_cookie *ipc, struct rtable **rtp) 1035{ 1036 struct inet_sock *inet = inet_sk(sk); 1037 struct ip_options_rcu *opt; 1038 struct rtable *rt; 1039 1040 /* 1041 * setup for corking. 1042 */ 1043 opt = ipc->opt; 1044 if (opt) { 1045 if (cork->opt == NULL) { 1046 cork->opt = kmalloc(sizeof(struct ip_options) + 40, 1047 sk->sk_allocation); 1048 if (unlikely(cork->opt == NULL)) 1049 return -ENOBUFS; 1050 } 1051 memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen); 1052 cork->flags |= IPCORK_OPT; 1053 cork->addr = ipc->addr; 1054 } 1055 rt = *rtp; 1056 if (unlikely(!rt)) 1057 return -EFAULT; 1058 /* 1059 * We steal reference to this route, caller should not release it 1060 */ 1061 *rtp = NULL; 1062 cork->fragsize = inet->pmtudisc == IP_PMTUDISC_PROBE ? 1063 rt->dst.dev->mtu : dst_mtu(rt->dst.path); 1064 cork->dst = &rt->dst; 1065 cork->length = 0; 1066 cork->tx_flags = ipc->tx_flags; 1067 cork->page = NULL; 1068 cork->off = 0; 1069 1070 return 0; 1071} 1072 1073/* 1074 * ip_append_data() and ip_append_page() can make one large IP datagram 1075 * from many pieces of data. Each pieces will be holded on the socket 1076 * until ip_push_pending_frames() is called. Each piece can be a page 1077 * or non-page data. 1078 * 1079 * Not only UDP, other transport protocols - e.g. raw sockets - can use 1080 * this interface potentially. 1081 * 1082 * LATER: length must be adjusted by pad at tail, when it is required. 1083 */ 1084int ip_append_data(struct sock *sk, 1085 int getfrag(void *from, char *to, int offset, int len, 1086 int odd, struct sk_buff *skb), 1087 void *from, int length, int transhdrlen, 1088 struct ipcm_cookie *ipc, struct rtable **rtp, 1089 unsigned int flags) 1090{ 1091 struct inet_sock *inet = inet_sk(sk); 1092 int err; 1093 1094 if (flags&MSG_PROBE) 1095 return 0; 1096 1097 if (skb_queue_empty(&sk->sk_write_queue)) { 1098 err = ip_setup_cork(sk, &inet->cork, ipc, rtp); 1099 if (err) 1100 return err; 1101 } else { 1102 transhdrlen = 0; 1103 } 1104 1105 return __ip_append_data(sk, &sk->sk_write_queue, &inet->cork, getfrag, 1106 from, length, transhdrlen, flags); 1107} 1108 1109ssize_t ip_append_page(struct sock *sk, struct page *page, 1110 int offset, size_t size, int flags) 1111{ 1112 struct inet_sock *inet = inet_sk(sk); 1113 struct sk_buff *skb; 1114 struct rtable *rt; 1115 struct ip_options *opt = NULL; 1116 int hh_len; 1117 int mtu; 1118 int len; 1119 int err; 1120 unsigned int maxfraglen, fragheaderlen, fraggap; 1121 1122 if (inet->hdrincl) 1123 return -EPERM; 1124 1125 if (flags&MSG_PROBE) 1126 return 0; 1127 1128 if (skb_queue_empty(&sk->sk_write_queue)) 1129 return -EINVAL; 1130 1131 rt = (struct rtable *)inet->cork.dst; 1132 if (inet->cork.flags & IPCORK_OPT) 1133 opt = inet->cork.opt; 1134 1135 if (!(rt->dst.dev->features&NETIF_F_SG)) 1136 return -EOPNOTSUPP; 1137 1138 hh_len = LL_RESERVED_SPACE(rt->dst.dev); 1139 mtu = inet->cork.fragsize; 1140 1141 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0); 1142 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen; 1143 1144 if (inet->cork.length + size > 0xFFFF - fragheaderlen) { 1145 ip_local_error(sk, EMSGSIZE, rt->rt_dst, inet->inet_dport, mtu); 1146 return -EMSGSIZE; 1147 } 1148 1149 if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL) 1150 return -EINVAL; 1151 1152 inet->cork.length += size; 1153 if ((size + skb->len > mtu) && 1154 (sk->sk_protocol == IPPROTO_UDP) && 1155 (rt->dst.dev->features & NETIF_F_UFO)) { 1156 skb_shinfo(skb)->gso_size = mtu - fragheaderlen; 1157 skb_shinfo(skb)->gso_type = SKB_GSO_UDP; 1158 } 1159 1160 1161 while (size > 0) { 1162 int i; 1163 1164 if (skb_is_gso(skb)) 1165 len = size; 1166 else { 1167 1168 /* Check if the remaining data fits into current packet. */ 1169 len = mtu - skb->len; 1170 if (len < size) 1171 len = maxfraglen - skb->len; 1172 } 1173 if (len <= 0) { 1174 struct sk_buff *skb_prev; 1175 int alloclen; 1176 1177 skb_prev = skb; 1178 fraggap = skb_prev->len - maxfraglen; 1179 1180 alloclen = fragheaderlen + hh_len + fraggap + 15; 1181 skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation); 1182 if (unlikely(!skb)) { 1183 err = -ENOBUFS; 1184 goto error; 1185 } 1186 1187 /* 1188 * Fill in the control structures 1189 */ 1190 skb->ip_summed = CHECKSUM_NONE; 1191 skb->csum = 0; 1192 skb_reserve(skb, hh_len); 1193 1194 /* 1195 * Find where to start putting bytes. 1196 */ 1197 skb_put(skb, fragheaderlen + fraggap); 1198 skb_reset_network_header(skb); 1199 skb->transport_header = (skb->network_header + 1200 fragheaderlen); 1201 if (fraggap) { 1202 skb->csum = skb_copy_and_csum_bits(skb_prev, 1203 maxfraglen, 1204 skb_transport_header(skb), 1205 fraggap, 0); 1206 skb_prev->csum = csum_sub(skb_prev->csum, 1207 skb->csum); 1208 pskb_trim_unique(skb_prev, maxfraglen); 1209 } 1210 1211 /* 1212 * Put the packet on the pending queue. 1213 */ 1214 __skb_queue_tail(&sk->sk_write_queue, skb); 1215 continue; 1216 } 1217 1218 i = skb_shinfo(skb)->nr_frags; 1219 if (len > size) 1220 len = size; 1221 if (skb_can_coalesce(skb, i, page, offset)) { 1222 skb_shinfo(skb)->frags[i-1].size += len; 1223 } else if (i < MAX_SKB_FRAGS) { 1224 get_page(page); 1225 skb_fill_page_desc(skb, i, page, offset, len); 1226 } else { 1227 err = -EMSGSIZE; 1228 goto error; 1229 } 1230 1231 if (skb->ip_summed == CHECKSUM_NONE) { 1232 __wsum csum; 1233 csum = csum_page(page, offset, len); 1234 skb->csum = csum_block_add(skb->csum, csum, skb->len); 1235 } 1236 1237 skb->len += len; 1238 skb->data_len += len; 1239 skb->truesize += len; 1240 atomic_add(len, &sk->sk_wmem_alloc); 1241 offset += len; 1242 size -= len; 1243 } 1244 return 0; 1245 1246error: 1247 inet->cork.length -= size; 1248 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS); 1249 return err; 1250} 1251 1252static void ip_cork_release(struct inet_cork *cork) 1253{ 1254 cork->flags &= ~IPCORK_OPT; 1255 kfree(cork->opt); 1256 cork->opt = NULL; 1257 dst_release(cork->dst); 1258 cork->dst = NULL; 1259} 1260 1261/* 1262 * Combined all pending IP fragments on the socket as one IP datagram 1263 * and push them out. 1264 */ 1265struct sk_buff *__ip_make_skb(struct sock *sk, 1266 struct sk_buff_head *queue, 1267 struct inet_cork *cork) 1268{ 1269 struct sk_buff *skb, *tmp_skb; 1270 struct sk_buff **tail_skb; 1271 struct inet_sock *inet = inet_sk(sk); 1272 struct net *net = sock_net(sk); 1273 struct ip_options *opt = NULL; 1274 struct rtable *rt = (struct rtable *)cork->dst; 1275 struct iphdr *iph; 1276 __be16 df = 0; 1277 __u8 ttl; 1278 1279 if ((skb = __skb_dequeue(queue)) == NULL) 1280 goto out; 1281 tail_skb = &(skb_shinfo(skb)->frag_list); 1282 1283 /* move skb->data to ip header from ext header */ 1284 if (skb->data < skb_network_header(skb)) 1285 __skb_pull(skb, skb_network_offset(skb)); 1286 while ((tmp_skb = __skb_dequeue(queue)) != NULL) { 1287 __skb_pull(tmp_skb, skb_network_header_len(skb)); 1288 *tail_skb = tmp_skb; 1289 tail_skb = &(tmp_skb->next); 1290 skb->len += tmp_skb->len; 1291 skb->data_len += tmp_skb->len; 1292 skb->truesize += tmp_skb->truesize; 1293 tmp_skb->destructor = NULL; 1294 tmp_skb->sk = NULL; 1295 } 1296 1297 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow 1298 * to fragment the frame generated here. No matter, what transforms 1299 * how transforms change size of the packet, it will come out. 1300 */ 1301 if (inet->pmtudisc < IP_PMTUDISC_DO) 1302 skb->local_df = 1; 1303 1304 /* DF bit is set when we want to see DF on outgoing frames. 1305 * If local_df is set too, we still allow to fragment this frame 1306 * locally. */ 1307 if (inet->pmtudisc >= IP_PMTUDISC_DO || 1308 (skb->len <= dst_mtu(&rt->dst) && 1309 ip_dont_fragment(sk, &rt->dst))) 1310 df = htons(IP_DF); 1311 1312 if (cork->flags & IPCORK_OPT) 1313 opt = cork->opt; 1314 1315 if (rt->rt_type == RTN_MULTICAST) 1316 ttl = inet->mc_ttl; 1317 else 1318 ttl = ip_select_ttl(inet, &rt->dst); 1319 1320 iph = (struct iphdr *)skb->data; 1321 iph->version = 4; 1322 iph->ihl = 5; 1323 if (opt) { 1324 iph->ihl += opt->optlen>>2; 1325 ip_options_build(skb, opt, cork->addr, rt, 0); 1326 } 1327 iph->tos = inet->tos; 1328 iph->frag_off = df; 1329 ip_select_ident(iph, &rt->dst, sk); 1330 iph->ttl = ttl; 1331 iph->protocol = sk->sk_protocol; 1332 iph->saddr = rt->rt_src; 1333 iph->daddr = rt->rt_dst; 1334 1335 skb->priority = sk->sk_priority; 1336 skb->mark = sk->sk_mark; 1337 /* 1338 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec 1339 * on dst refcount 1340 */ 1341 cork->dst = NULL; 1342 skb_dst_set(skb, &rt->dst); 1343 1344 if (iph->protocol == IPPROTO_ICMP) 1345 icmp_out_count(net, ((struct icmphdr *) 1346 skb_transport_header(skb))->type); 1347 1348 ip_cork_release(cork); 1349out: 1350 return skb; 1351} 1352 1353int ip_send_skb(struct sk_buff *skb) 1354{ 1355 struct net *net = sock_net(skb->sk); 1356 int err; 1357 1358 err = ip_local_out(skb); 1359 if (err) { 1360 if (err > 0) 1361 err = net_xmit_errno(err); 1362 if (err) 1363 IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS); 1364 } 1365 1366 return err; 1367} 1368 1369int ip_push_pending_frames(struct sock *sk) 1370{ 1371 struct sk_buff *skb; 1372 1373 skb = ip_finish_skb(sk); 1374 if (!skb) 1375 return 0; 1376 1377 /* Netfilter gets whole the not fragmented skb. */ 1378 return ip_send_skb(skb); 1379} 1380 1381/* 1382 * Throw away all pending data on the socket. 1383 */ 1384static void __ip_flush_pending_frames(struct sock *sk, 1385 struct sk_buff_head *queue, 1386 struct inet_cork *cork) 1387{ 1388 struct sk_buff *skb; 1389 1390 while ((skb = __skb_dequeue_tail(queue)) != NULL) 1391 kfree_skb(skb); 1392 1393 ip_cork_release(cork); 1394} 1395 1396void ip_flush_pending_frames(struct sock *sk) 1397{ 1398 __ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork); 1399} 1400 1401struct sk_buff *ip_make_skb(struct sock *sk, 1402 int getfrag(void *from, char *to, int offset, 1403 int len, int odd, struct sk_buff *skb), 1404 void *from, int length, int transhdrlen, 1405 struct ipcm_cookie *ipc, struct rtable **rtp, 1406 unsigned int flags) 1407{ 1408 struct inet_cork cork = {}; 1409 struct sk_buff_head queue; 1410 int err; 1411 1412 if (flags & MSG_PROBE) 1413 return NULL; 1414 1415 __skb_queue_head_init(&queue); 1416 1417 err = ip_setup_cork(sk, &cork, ipc, rtp); 1418 if (err) 1419 return ERR_PTR(err); 1420 1421 err = __ip_append_data(sk, &queue, &cork, getfrag, 1422 from, length, transhdrlen, flags); 1423 if (err) { 1424 __ip_flush_pending_frames(sk, &queue, &cork); 1425 return ERR_PTR(err); 1426 } 1427 1428 return __ip_make_skb(sk, &queue, &cork); 1429} 1430 1431/* 1432 * Fetch data from kernel space and fill in checksum if needed. 1433 */ 1434static int ip_reply_glue_bits(void *dptr, char *to, int offset, 1435 int len, int odd, struct sk_buff *skb) 1436{ 1437 __wsum csum; 1438 1439 csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0); 1440 skb->csum = csum_block_add(skb->csum, csum, odd); 1441 return 0; 1442} 1443 1444/* 1445 * Generic function to send a packet as reply to another packet. 1446 * Used to send TCP resets so far. ICMP should use this function too. 1447 * 1448 * Should run single threaded per socket because it uses the sock 1449 * structure to pass arguments. 1450 */ 1451void ip_send_reply(struct sock *sk, struct sk_buff *skb, struct ip_reply_arg *arg, 1452 unsigned int len) 1453{ 1454 struct inet_sock *inet = inet_sk(sk); 1455 struct ip_options_data replyopts; 1456 struct ipcm_cookie ipc; 1457 __be32 daddr; 1458 struct rtable *rt = skb_rtable(skb); 1459 1460 if (ip_options_echo(&replyopts.opt.opt, skb)) 1461 return; 1462 1463 daddr = ipc.addr = rt->rt_src; 1464 ipc.opt = NULL; 1465 ipc.tx_flags = 0; 1466 1467 if (replyopts.opt.opt.optlen) { 1468 ipc.opt = &replyopts.opt; 1469 1470 if (replyopts.opt.opt.srr) 1471 daddr = replyopts.opt.opt.faddr; 1472 } 1473 1474 { 1475 struct flowi4 fl4; 1476 1477 flowi4_init_output(&fl4, arg->bound_dev_if, 0, 1478 RT_TOS(ip_hdr(skb)->tos), 1479 RT_SCOPE_UNIVERSE, sk->sk_protocol, 1480 ip_reply_arg_flowi_flags(arg), 1481 daddr, rt->rt_spec_dst, 1482 tcp_hdr(skb)->source, tcp_hdr(skb)->dest); 1483 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4)); 1484 rt = ip_route_output_key(sock_net(sk), &fl4); 1485 if (IS_ERR(rt)) 1486 return; 1487 } 1488 1489 /* And let IP do all the hard work. 1490 1491 This chunk is not reenterable, hence spinlock. 1492 Note that it uses the fact, that this function is called 1493 with locally disabled BH and that sk cannot be already spinlocked. 1494 */ 1495 bh_lock_sock(sk); 1496 inet->tos = ip_hdr(skb)->tos; 1497 sk->sk_priority = skb->priority; 1498 sk->sk_protocol = ip_hdr(skb)->protocol; 1499 sk->sk_bound_dev_if = arg->bound_dev_if; 1500 ip_append_data(sk, ip_reply_glue_bits, arg->iov->iov_base, len, 0, 1501 &ipc, &rt, MSG_DONTWAIT); 1502 if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) { 1503 if (arg->csumoffset >= 0) 1504 *((__sum16 *)skb_transport_header(skb) + 1505 arg->csumoffset) = csum_fold(csum_add(skb->csum, 1506 arg->csum)); 1507 skb->ip_summed = CHECKSUM_NONE; 1508 ip_push_pending_frames(sk); 1509 } 1510 1511 bh_unlock_sock(sk); 1512 1513 ip_rt_put(rt); 1514} 1515 1516void __init ip_init(void) 1517{ 1518 ip_rt_init(); 1519 inet_initpeers(); 1520 1521#if defined(CONFIG_IP_MULTICAST) && defined(CONFIG_PROC_FS) 1522 igmp_mc_proc_init(); 1523#endif 1524} 1525