ip_output.c revision e110861f86094cd78cc85593b873970092deb43a
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 <linux/module.h> 47#include <linux/types.h> 48#include <linux/kernel.h> 49#include <linux/mm.h> 50#include <linux/string.h> 51#include <linux/errno.h> 52#include <linux/highmem.h> 53#include <linux/slab.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 83int sysctl_ip_default_ttl __read_mostly = IPDEFTTL; 84EXPORT_SYMBOL(sysctl_ip_default_ttl); 85 86/* Generate a checksum for an outgoing IP datagram. */ 87void ip_send_check(struct iphdr *iph) 88{ 89 iph->check = 0; 90 iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl); 91} 92EXPORT_SYMBOL(ip_send_check); 93 94int __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 104int ip_local_out_sk(struct sock *sk, struct sk_buff *skb) 105{ 106 int err; 107 108 err = __ip_local_out(skb); 109 if (likely(err == 1)) 110 err = dst_output_sk(sk, skb); 111 112 return err; 113} 114EXPORT_SYMBOL_GPL(ip_local_out_sk); 115 116static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst) 117{ 118 int ttl = inet->uc_ttl; 119 120 if (ttl < 0) 121 ttl = ip4_dst_hoplimit(dst); 122 return ttl; 123} 124 125/* 126 * Add an ip header to a skbuff and send it out. 127 * 128 */ 129int ip_build_and_send_pkt(struct sk_buff *skb, struct sock *sk, 130 __be32 saddr, __be32 daddr, struct ip_options_rcu *opt) 131{ 132 struct inet_sock *inet = inet_sk(sk); 133 struct rtable *rt = skb_rtable(skb); 134 struct iphdr *iph; 135 136 /* Build the IP header. */ 137 skb_push(skb, sizeof(struct iphdr) + (opt ? opt->opt.optlen : 0)); 138 skb_reset_network_header(skb); 139 iph = ip_hdr(skb); 140 iph->version = 4; 141 iph->ihl = 5; 142 iph->tos = inet->tos; 143 if (ip_dont_fragment(sk, &rt->dst)) 144 iph->frag_off = htons(IP_DF); 145 else 146 iph->frag_off = 0; 147 iph->ttl = ip_select_ttl(inet, &rt->dst); 148 iph->daddr = (opt && opt->opt.srr ? opt->opt.faddr : daddr); 149 iph->saddr = saddr; 150 iph->protocol = sk->sk_protocol; 151 ip_select_ident(skb, &rt->dst, sk); 152 153 if (opt && opt->opt.optlen) { 154 iph->ihl += opt->opt.optlen>>2; 155 ip_options_build(skb, &opt->opt, daddr, rt, 0); 156 } 157 158 skb->priority = sk->sk_priority; 159 skb->mark = sk->sk_mark; 160 161 /* Send it out. */ 162 return ip_local_out(skb); 163} 164EXPORT_SYMBOL_GPL(ip_build_and_send_pkt); 165 166static inline int ip_finish_output2(struct sk_buff *skb) 167{ 168 struct dst_entry *dst = skb_dst(skb); 169 struct rtable *rt = (struct rtable *)dst; 170 struct net_device *dev = dst->dev; 171 unsigned int hh_len = LL_RESERVED_SPACE(dev); 172 struct neighbour *neigh; 173 u32 nexthop; 174 175 if (rt->rt_type == RTN_MULTICAST) { 176 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUTMCAST, skb->len); 177 } else if (rt->rt_type == RTN_BROADCAST) 178 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUTBCAST, skb->len); 179 180 /* Be paranoid, rather than too clever. */ 181 if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) { 182 struct sk_buff *skb2; 183 184 skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev)); 185 if (skb2 == NULL) { 186 kfree_skb(skb); 187 return -ENOMEM; 188 } 189 if (skb->sk) 190 skb_set_owner_w(skb2, skb->sk); 191 consume_skb(skb); 192 skb = skb2; 193 } 194 195 rcu_read_lock_bh(); 196 nexthop = (__force u32) rt_nexthop(rt, ip_hdr(skb)->daddr); 197 neigh = __ipv4_neigh_lookup_noref(dev, nexthop); 198 if (unlikely(!neigh)) 199 neigh = __neigh_create(&arp_tbl, &nexthop, dev, false); 200 if (!IS_ERR(neigh)) { 201 int res = dst_neigh_output(dst, neigh, skb); 202 203 rcu_read_unlock_bh(); 204 return res; 205 } 206 rcu_read_unlock_bh(); 207 208 net_dbg_ratelimited("%s: No header cache and no neighbour!\n", 209 __func__); 210 kfree_skb(skb); 211 return -EINVAL; 212} 213 214static int ip_finish_output_gso(struct sk_buff *skb) 215{ 216 netdev_features_t features; 217 struct sk_buff *segs; 218 int ret = 0; 219 220 /* common case: locally created skb or seglen is <= mtu */ 221 if (((IPCB(skb)->flags & IPSKB_FORWARDED) == 0) || 222 skb_gso_network_seglen(skb) <= ip_skb_dst_mtu(skb)) 223 return ip_finish_output2(skb); 224 225 /* Slowpath - GSO segment length is exceeding the dst MTU. 226 * 227 * This can happen in two cases: 228 * 1) TCP GRO packet, DF bit not set 229 * 2) skb arrived via virtio-net, we thus get TSO/GSO skbs directly 230 * from host network stack. 231 */ 232 features = netif_skb_features(skb); 233 segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK); 234 if (IS_ERR(segs)) { 235 kfree_skb(skb); 236 return -ENOMEM; 237 } 238 239 consume_skb(skb); 240 241 do { 242 struct sk_buff *nskb = segs->next; 243 int err; 244 245 segs->next = NULL; 246 err = ip_fragment(segs, ip_finish_output2); 247 248 if (err && ret == 0) 249 ret = err; 250 segs = nskb; 251 } while (segs); 252 253 return ret; 254} 255 256static int ip_finish_output(struct sk_buff *skb) 257{ 258#if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM) 259 /* Policy lookup after SNAT yielded a new policy */ 260 if (skb_dst(skb)->xfrm != NULL) { 261 IPCB(skb)->flags |= IPSKB_REROUTED; 262 return dst_output(skb); 263 } 264#endif 265 if (skb_is_gso(skb)) 266 return ip_finish_output_gso(skb); 267 268 if (skb->len > ip_skb_dst_mtu(skb)) 269 return ip_fragment(skb, ip_finish_output2); 270 271 return ip_finish_output2(skb); 272} 273 274int ip_mc_output(struct sock *sk, struct sk_buff *skb) 275{ 276 struct rtable *rt = skb_rtable(skb); 277 struct net_device *dev = rt->dst.dev; 278 279 /* 280 * If the indicated interface is up and running, send the packet. 281 */ 282 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len); 283 284 skb->dev = dev; 285 skb->protocol = htons(ETH_P_IP); 286 287 /* 288 * Multicasts are looped back for other local users 289 */ 290 291 if (rt->rt_flags&RTCF_MULTICAST) { 292 if (sk_mc_loop(sk) 293#ifdef CONFIG_IP_MROUTE 294 /* Small optimization: do not loopback not local frames, 295 which returned after forwarding; they will be dropped 296 by ip_mr_input in any case. 297 Note, that local frames are looped back to be delivered 298 to local recipients. 299 300 This check is duplicated in ip_mr_input at the moment. 301 */ 302 && 303 ((rt->rt_flags & RTCF_LOCAL) || 304 !(IPCB(skb)->flags & IPSKB_FORWARDED)) 305#endif 306 ) { 307 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC); 308 if (newskb) 309 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, 310 newskb, NULL, newskb->dev, 311 dev_loopback_xmit); 312 } 313 314 /* Multicasts with ttl 0 must not go beyond the host */ 315 316 if (ip_hdr(skb)->ttl == 0) { 317 kfree_skb(skb); 318 return 0; 319 } 320 } 321 322 if (rt->rt_flags&RTCF_BROADCAST) { 323 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC); 324 if (newskb) 325 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, newskb, 326 NULL, newskb->dev, dev_loopback_xmit); 327 } 328 329 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb, NULL, 330 skb->dev, ip_finish_output, 331 !(IPCB(skb)->flags & IPSKB_REROUTED)); 332} 333 334int ip_output(struct sock *sk, struct sk_buff *skb) 335{ 336 struct net_device *dev = skb_dst(skb)->dev; 337 338 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len); 339 340 skb->dev = dev; 341 skb->protocol = htons(ETH_P_IP); 342 343 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb, NULL, dev, 344 ip_finish_output, 345 !(IPCB(skb)->flags & IPSKB_REROUTED)); 346} 347 348/* 349 * copy saddr and daddr, possibly using 64bit load/stores 350 * Equivalent to : 351 * iph->saddr = fl4->saddr; 352 * iph->daddr = fl4->daddr; 353 */ 354static void ip_copy_addrs(struct iphdr *iph, const struct flowi4 *fl4) 355{ 356 BUILD_BUG_ON(offsetof(typeof(*fl4), daddr) != 357 offsetof(typeof(*fl4), saddr) + sizeof(fl4->saddr)); 358 memcpy(&iph->saddr, &fl4->saddr, 359 sizeof(fl4->saddr) + sizeof(fl4->daddr)); 360} 361 362/* Note: skb->sk can be different from sk, in case of tunnels */ 363int ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl) 364{ 365 struct inet_sock *inet = inet_sk(sk); 366 struct ip_options_rcu *inet_opt; 367 struct flowi4 *fl4; 368 struct rtable *rt; 369 struct iphdr *iph; 370 int res; 371 372 /* Skip all of this if the packet is already routed, 373 * f.e. by something like SCTP. 374 */ 375 rcu_read_lock(); 376 inet_opt = rcu_dereference(inet->inet_opt); 377 fl4 = &fl->u.ip4; 378 rt = skb_rtable(skb); 379 if (rt != NULL) 380 goto packet_routed; 381 382 /* Make sure we can route this packet. */ 383 rt = (struct rtable *)__sk_dst_check(sk, 0); 384 if (rt == NULL) { 385 __be32 daddr; 386 387 /* Use correct destination address if we have options. */ 388 daddr = inet->inet_daddr; 389 if (inet_opt && inet_opt->opt.srr) 390 daddr = inet_opt->opt.faddr; 391 392 /* If this fails, retransmit mechanism of transport layer will 393 * keep trying until route appears or the connection times 394 * itself out. 395 */ 396 rt = ip_route_output_ports(sock_net(sk), fl4, sk, 397 daddr, inet->inet_saddr, 398 inet->inet_dport, 399 inet->inet_sport, 400 sk->sk_protocol, 401 RT_CONN_FLAGS(sk), 402 sk->sk_bound_dev_if); 403 if (IS_ERR(rt)) 404 goto no_route; 405 sk_setup_caps(sk, &rt->dst); 406 } 407 skb_dst_set_noref(skb, &rt->dst); 408 409packet_routed: 410 if (inet_opt && inet_opt->opt.is_strictroute && rt->rt_uses_gateway) 411 goto no_route; 412 413 /* OK, we know where to send it, allocate and build IP header. */ 414 skb_push(skb, sizeof(struct iphdr) + (inet_opt ? inet_opt->opt.optlen : 0)); 415 skb_reset_network_header(skb); 416 iph = ip_hdr(skb); 417 *((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (inet->tos & 0xff)); 418 if (ip_dont_fragment(sk, &rt->dst) && !skb->ignore_df) 419 iph->frag_off = htons(IP_DF); 420 else 421 iph->frag_off = 0; 422 iph->ttl = ip_select_ttl(inet, &rt->dst); 423 iph->protocol = sk->sk_protocol; 424 ip_copy_addrs(iph, fl4); 425 426 /* Transport layer set skb->h.foo itself. */ 427 428 if (inet_opt && inet_opt->opt.optlen) { 429 iph->ihl += inet_opt->opt.optlen >> 2; 430 ip_options_build(skb, &inet_opt->opt, inet->inet_daddr, rt, 0); 431 } 432 433 ip_select_ident_more(skb, &rt->dst, sk, 434 (skb_shinfo(skb)->gso_segs ?: 1) - 1); 435 436 /* TODO : should we use skb->sk here instead of sk ? */ 437 skb->priority = sk->sk_priority; 438 skb->mark = sk->sk_mark; 439 440 res = ip_local_out(skb); 441 rcu_read_unlock(); 442 return res; 443 444no_route: 445 rcu_read_unlock(); 446 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES); 447 kfree_skb(skb); 448 return -EHOSTUNREACH; 449} 450EXPORT_SYMBOL(ip_queue_xmit); 451 452 453static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from) 454{ 455 to->pkt_type = from->pkt_type; 456 to->priority = from->priority; 457 to->protocol = from->protocol; 458 skb_dst_drop(to); 459 skb_dst_copy(to, from); 460 to->dev = from->dev; 461 to->mark = from->mark; 462 463 /* Copy the flags to each fragment. */ 464 IPCB(to)->flags = IPCB(from)->flags; 465 466#ifdef CONFIG_NET_SCHED 467 to->tc_index = from->tc_index; 468#endif 469 nf_copy(to, from); 470#if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE) 471 to->ipvs_property = from->ipvs_property; 472#endif 473 skb_copy_secmark(to, from); 474} 475 476/* 477 * This IP datagram is too large to be sent in one piece. Break it up into 478 * smaller pieces (each of size equal to IP header plus 479 * a block of the data of the original IP data part) that will yet fit in a 480 * single device frame, and queue such a frame for sending. 481 */ 482 483int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *)) 484{ 485 struct iphdr *iph; 486 int ptr; 487 struct net_device *dev; 488 struct sk_buff *skb2; 489 unsigned int mtu, hlen, left, len, ll_rs; 490 int offset; 491 __be16 not_last_frag; 492 struct rtable *rt = skb_rtable(skb); 493 int err = 0; 494 495 dev = rt->dst.dev; 496 497 /* 498 * Point into the IP datagram header. 499 */ 500 501 iph = ip_hdr(skb); 502 503 mtu = ip_skb_dst_mtu(skb); 504 if (unlikely(((iph->frag_off & htons(IP_DF)) && !skb->ignore_df) || 505 (IPCB(skb)->frag_max_size && 506 IPCB(skb)->frag_max_size > mtu))) { 507 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); 508 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, 509 htonl(mtu)); 510 kfree_skb(skb); 511 return -EMSGSIZE; 512 } 513 514 /* 515 * Setup starting values. 516 */ 517 518 hlen = iph->ihl * 4; 519 mtu = mtu - hlen; /* Size of data space */ 520#ifdef CONFIG_BRIDGE_NETFILTER 521 if (skb->nf_bridge) 522 mtu -= nf_bridge_mtu_reduction(skb); 523#endif 524 IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE; 525 526 /* When frag_list is given, use it. First, check its validity: 527 * some transformers could create wrong frag_list or break existing 528 * one, it is not prohibited. In this case fall back to copying. 529 * 530 * LATER: this step can be merged to real generation of fragments, 531 * we can switch to copy when see the first bad fragment. 532 */ 533 if (skb_has_frag_list(skb)) { 534 struct sk_buff *frag, *frag2; 535 int first_len = skb_pagelen(skb); 536 537 if (first_len - hlen > mtu || 538 ((first_len - hlen) & 7) || 539 ip_is_fragment(iph) || 540 skb_cloned(skb)) 541 goto slow_path; 542 543 skb_walk_frags(skb, frag) { 544 /* Correct geometry. */ 545 if (frag->len > mtu || 546 ((frag->len & 7) && frag->next) || 547 skb_headroom(frag) < hlen) 548 goto slow_path_clean; 549 550 /* Partially cloned skb? */ 551 if (skb_shared(frag)) 552 goto slow_path_clean; 553 554 BUG_ON(frag->sk); 555 if (skb->sk) { 556 frag->sk = skb->sk; 557 frag->destructor = sock_wfree; 558 } 559 skb->truesize -= frag->truesize; 560 } 561 562 /* Everything is OK. Generate! */ 563 564 err = 0; 565 offset = 0; 566 frag = skb_shinfo(skb)->frag_list; 567 skb_frag_list_init(skb); 568 skb->data_len = first_len - skb_headlen(skb); 569 skb->len = first_len; 570 iph->tot_len = htons(first_len); 571 iph->frag_off = htons(IP_MF); 572 ip_send_check(iph); 573 574 for (;;) { 575 /* Prepare header of the next frame, 576 * before previous one went down. */ 577 if (frag) { 578 frag->ip_summed = CHECKSUM_NONE; 579 skb_reset_transport_header(frag); 580 __skb_push(frag, hlen); 581 skb_reset_network_header(frag); 582 memcpy(skb_network_header(frag), iph, hlen); 583 iph = ip_hdr(frag); 584 iph->tot_len = htons(frag->len); 585 ip_copy_metadata(frag, skb); 586 if (offset == 0) 587 ip_options_fragment(frag); 588 offset += skb->len - hlen; 589 iph->frag_off = htons(offset>>3); 590 if (frag->next != NULL) 591 iph->frag_off |= htons(IP_MF); 592 /* Ready, complete checksum */ 593 ip_send_check(iph); 594 } 595 596 err = output(skb); 597 598 if (!err) 599 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES); 600 if (err || !frag) 601 break; 602 603 skb = frag; 604 frag = skb->next; 605 skb->next = NULL; 606 } 607 608 if (err == 0) { 609 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS); 610 return 0; 611 } 612 613 while (frag) { 614 skb = frag->next; 615 kfree_skb(frag); 616 frag = skb; 617 } 618 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); 619 return err; 620 621slow_path_clean: 622 skb_walk_frags(skb, frag2) { 623 if (frag2 == frag) 624 break; 625 frag2->sk = NULL; 626 frag2->destructor = NULL; 627 skb->truesize += frag2->truesize; 628 } 629 } 630 631slow_path: 632 /* for offloaded checksums cleanup checksum before fragmentation */ 633 if ((skb->ip_summed == CHECKSUM_PARTIAL) && skb_checksum_help(skb)) 634 goto fail; 635 iph = ip_hdr(skb); 636 637 left = skb->len - hlen; /* Space per frame */ 638 ptr = hlen; /* Where to start from */ 639 640 /* for bridged IP traffic encapsulated inside f.e. a vlan header, 641 * we need to make room for the encapsulating header 642 */ 643 ll_rs = LL_RESERVED_SPACE_EXTRA(rt->dst.dev, nf_bridge_pad(skb)); 644 645 /* 646 * Fragment the datagram. 647 */ 648 649 offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3; 650 not_last_frag = iph->frag_off & htons(IP_MF); 651 652 /* 653 * Keep copying data until we run out. 654 */ 655 656 while (left > 0) { 657 len = left; 658 /* IF: it doesn't fit, use 'mtu' - the data space left */ 659 if (len > mtu) 660 len = mtu; 661 /* IF: we are not sending up to and including the packet end 662 then align the next start on an eight byte boundary */ 663 if (len < left) { 664 len &= ~7; 665 } 666 /* 667 * Allocate buffer. 668 */ 669 670 if ((skb2 = alloc_skb(len+hlen+ll_rs, GFP_ATOMIC)) == NULL) { 671 NETDEBUG(KERN_INFO "IP: frag: no memory for new fragment!\n"); 672 err = -ENOMEM; 673 goto fail; 674 } 675 676 /* 677 * Set up data on packet 678 */ 679 680 ip_copy_metadata(skb2, skb); 681 skb_reserve(skb2, ll_rs); 682 skb_put(skb2, len + hlen); 683 skb_reset_network_header(skb2); 684 skb2->transport_header = skb2->network_header + hlen; 685 686 /* 687 * Charge the memory for the fragment to any owner 688 * it might possess 689 */ 690 691 if (skb->sk) 692 skb_set_owner_w(skb2, skb->sk); 693 694 /* 695 * Copy the packet header into the new buffer. 696 */ 697 698 skb_copy_from_linear_data(skb, skb_network_header(skb2), hlen); 699 700 /* 701 * Copy a block of the IP datagram. 702 */ 703 if (skb_copy_bits(skb, ptr, skb_transport_header(skb2), len)) 704 BUG(); 705 left -= len; 706 707 /* 708 * Fill in the new header fields. 709 */ 710 iph = ip_hdr(skb2); 711 iph->frag_off = htons((offset >> 3)); 712 713 /* ANK: dirty, but effective trick. Upgrade options only if 714 * the segment to be fragmented was THE FIRST (otherwise, 715 * options are already fixed) and make it ONCE 716 * on the initial skb, so that all the following fragments 717 * will inherit fixed options. 718 */ 719 if (offset == 0) 720 ip_options_fragment(skb); 721 722 /* 723 * Added AC : If we are fragmenting a fragment that's not the 724 * last fragment then keep MF on each bit 725 */ 726 if (left > 0 || not_last_frag) 727 iph->frag_off |= htons(IP_MF); 728 ptr += len; 729 offset += len; 730 731 /* 732 * Put this fragment into the sending queue. 733 */ 734 iph->tot_len = htons(len + hlen); 735 736 ip_send_check(iph); 737 738 err = output(skb2); 739 if (err) 740 goto fail; 741 742 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES); 743 } 744 consume_skb(skb); 745 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS); 746 return err; 747 748fail: 749 kfree_skb(skb); 750 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); 751 return err; 752} 753EXPORT_SYMBOL(ip_fragment); 754 755int 756ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb) 757{ 758 struct iovec *iov = from; 759 760 if (skb->ip_summed == CHECKSUM_PARTIAL) { 761 if (memcpy_fromiovecend(to, iov, offset, len) < 0) 762 return -EFAULT; 763 } else { 764 __wsum csum = 0; 765 if (csum_partial_copy_fromiovecend(to, iov, offset, len, &csum) < 0) 766 return -EFAULT; 767 skb->csum = csum_block_add(skb->csum, csum, odd); 768 } 769 return 0; 770} 771EXPORT_SYMBOL(ip_generic_getfrag); 772 773static inline __wsum 774csum_page(struct page *page, int offset, int copy) 775{ 776 char *kaddr; 777 __wsum csum; 778 kaddr = kmap(page); 779 csum = csum_partial(kaddr + offset, copy, 0); 780 kunmap(page); 781 return csum; 782} 783 784static inline int ip_ufo_append_data(struct sock *sk, 785 struct sk_buff_head *queue, 786 int getfrag(void *from, char *to, int offset, int len, 787 int odd, struct sk_buff *skb), 788 void *from, int length, int hh_len, int fragheaderlen, 789 int transhdrlen, int maxfraglen, unsigned int flags) 790{ 791 struct sk_buff *skb; 792 int err; 793 794 /* There is support for UDP fragmentation offload by network 795 * device, so create one single skb packet containing complete 796 * udp datagram 797 */ 798 if ((skb = skb_peek_tail(queue)) == NULL) { 799 skb = sock_alloc_send_skb(sk, 800 hh_len + fragheaderlen + transhdrlen + 20, 801 (flags & MSG_DONTWAIT), &err); 802 803 if (skb == NULL) 804 return err; 805 806 /* reserve space for Hardware header */ 807 skb_reserve(skb, hh_len); 808 809 /* create space for UDP/IP header */ 810 skb_put(skb, fragheaderlen + transhdrlen); 811 812 /* initialize network header pointer */ 813 skb_reset_network_header(skb); 814 815 /* initialize protocol header pointer */ 816 skb->transport_header = skb->network_header + fragheaderlen; 817 818 skb->csum = 0; 819 820 821 __skb_queue_tail(queue, skb); 822 } else if (skb_is_gso(skb)) { 823 goto append; 824 } 825 826 skb->ip_summed = CHECKSUM_PARTIAL; 827 /* specify the length of each IP datagram fragment */ 828 skb_shinfo(skb)->gso_size = maxfraglen - fragheaderlen; 829 skb_shinfo(skb)->gso_type = SKB_GSO_UDP; 830 831append: 832 return skb_append_datato_frags(sk, skb, getfrag, from, 833 (length - transhdrlen)); 834} 835 836static int __ip_append_data(struct sock *sk, 837 struct flowi4 *fl4, 838 struct sk_buff_head *queue, 839 struct inet_cork *cork, 840 struct page_frag *pfrag, 841 int getfrag(void *from, char *to, int offset, 842 int len, int odd, struct sk_buff *skb), 843 void *from, int length, int transhdrlen, 844 unsigned int flags) 845{ 846 struct inet_sock *inet = inet_sk(sk); 847 struct sk_buff *skb; 848 849 struct ip_options *opt = cork->opt; 850 int hh_len; 851 int exthdrlen; 852 int mtu; 853 int copy; 854 int err; 855 int offset = 0; 856 unsigned int maxfraglen, fragheaderlen, maxnonfragsize; 857 int csummode = CHECKSUM_NONE; 858 struct rtable *rt = (struct rtable *)cork->dst; 859 860 skb = skb_peek_tail(queue); 861 862 exthdrlen = !skb ? rt->dst.header_len : 0; 863 mtu = cork->fragsize; 864 865 hh_len = LL_RESERVED_SPACE(rt->dst.dev); 866 867 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0); 868 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen; 869 maxnonfragsize = ip_sk_ignore_df(sk) ? 0xFFFF : mtu; 870 871 if (cork->length + length > maxnonfragsize - fragheaderlen) { 872 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport, 873 mtu - (opt ? opt->optlen : 0)); 874 return -EMSGSIZE; 875 } 876 877 /* 878 * transhdrlen > 0 means that this is the first fragment and we wish 879 * it won't be fragmented in the future. 880 */ 881 if (transhdrlen && 882 length + fragheaderlen <= mtu && 883 rt->dst.dev->features & NETIF_F_V4_CSUM && 884 !exthdrlen) 885 csummode = CHECKSUM_PARTIAL; 886 887 cork->length += length; 888 if (((length > mtu) || (skb && skb_is_gso(skb))) && 889 (sk->sk_protocol == IPPROTO_UDP) && 890 (rt->dst.dev->features & NETIF_F_UFO) && !rt->dst.header_len) { 891 err = ip_ufo_append_data(sk, queue, getfrag, from, length, 892 hh_len, fragheaderlen, transhdrlen, 893 maxfraglen, flags); 894 if (err) 895 goto error; 896 return 0; 897 } 898 899 /* So, what's going on in the loop below? 900 * 901 * We use calculated fragment length to generate chained skb, 902 * each of segments is IP fragment ready for sending to network after 903 * adding appropriate IP header. 904 */ 905 906 if (!skb) 907 goto alloc_new_skb; 908 909 while (length > 0) { 910 /* Check if the remaining data fits into current packet. */ 911 copy = mtu - skb->len; 912 if (copy < length) 913 copy = maxfraglen - skb->len; 914 if (copy <= 0) { 915 char *data; 916 unsigned int datalen; 917 unsigned int fraglen; 918 unsigned int fraggap; 919 unsigned int alloclen; 920 struct sk_buff *skb_prev; 921alloc_new_skb: 922 skb_prev = skb; 923 if (skb_prev) 924 fraggap = skb_prev->len - maxfraglen; 925 else 926 fraggap = 0; 927 928 /* 929 * If remaining data exceeds the mtu, 930 * we know we need more fragment(s). 931 */ 932 datalen = length + fraggap; 933 if (datalen > mtu - fragheaderlen) 934 datalen = maxfraglen - fragheaderlen; 935 fraglen = datalen + fragheaderlen; 936 937 if ((flags & MSG_MORE) && 938 !(rt->dst.dev->features&NETIF_F_SG)) 939 alloclen = mtu; 940 else 941 alloclen = fraglen; 942 943 alloclen += exthdrlen; 944 945 /* The last fragment gets additional space at tail. 946 * Note, with MSG_MORE we overallocate on fragments, 947 * because we have no idea what fragment will be 948 * the last. 949 */ 950 if (datalen == length + fraggap) 951 alloclen += rt->dst.trailer_len; 952 953 if (transhdrlen) { 954 skb = sock_alloc_send_skb(sk, 955 alloclen + hh_len + 15, 956 (flags & MSG_DONTWAIT), &err); 957 } else { 958 skb = NULL; 959 if (atomic_read(&sk->sk_wmem_alloc) <= 960 2 * sk->sk_sndbuf) 961 skb = sock_wmalloc(sk, 962 alloclen + hh_len + 15, 1, 963 sk->sk_allocation); 964 if (unlikely(skb == NULL)) 965 err = -ENOBUFS; 966 else 967 /* only the initial fragment is 968 time stamped */ 969 cork->tx_flags = 0; 970 } 971 if (skb == NULL) 972 goto error; 973 974 /* 975 * Fill in the control structures 976 */ 977 skb->ip_summed = csummode; 978 skb->csum = 0; 979 skb_reserve(skb, hh_len); 980 skb_shinfo(skb)->tx_flags = cork->tx_flags; 981 982 /* 983 * Find where to start putting bytes. 984 */ 985 data = skb_put(skb, fraglen + exthdrlen); 986 skb_set_network_header(skb, exthdrlen); 987 skb->transport_header = (skb->network_header + 988 fragheaderlen); 989 data += fragheaderlen + exthdrlen; 990 991 if (fraggap) { 992 skb->csum = skb_copy_and_csum_bits( 993 skb_prev, maxfraglen, 994 data + transhdrlen, fraggap, 0); 995 skb_prev->csum = csum_sub(skb_prev->csum, 996 skb->csum); 997 data += fraggap; 998 pskb_trim_unique(skb_prev, maxfraglen); 999 } 1000 1001 copy = datalen - transhdrlen - fraggap; 1002 if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) { 1003 err = -EFAULT; 1004 kfree_skb(skb); 1005 goto error; 1006 } 1007 1008 offset += copy; 1009 length -= datalen - fraggap; 1010 transhdrlen = 0; 1011 exthdrlen = 0; 1012 csummode = CHECKSUM_NONE; 1013 1014 /* 1015 * Put the packet on the pending queue. 1016 */ 1017 __skb_queue_tail(queue, skb); 1018 continue; 1019 } 1020 1021 if (copy > length) 1022 copy = length; 1023 1024 if (!(rt->dst.dev->features&NETIF_F_SG)) { 1025 unsigned int off; 1026 1027 off = skb->len; 1028 if (getfrag(from, skb_put(skb, copy), 1029 offset, copy, off, skb) < 0) { 1030 __skb_trim(skb, off); 1031 err = -EFAULT; 1032 goto error; 1033 } 1034 } else { 1035 int i = skb_shinfo(skb)->nr_frags; 1036 1037 err = -ENOMEM; 1038 if (!sk_page_frag_refill(sk, pfrag)) 1039 goto error; 1040 1041 if (!skb_can_coalesce(skb, i, pfrag->page, 1042 pfrag->offset)) { 1043 err = -EMSGSIZE; 1044 if (i == MAX_SKB_FRAGS) 1045 goto error; 1046 1047 __skb_fill_page_desc(skb, i, pfrag->page, 1048 pfrag->offset, 0); 1049 skb_shinfo(skb)->nr_frags = ++i; 1050 get_page(pfrag->page); 1051 } 1052 copy = min_t(int, copy, pfrag->size - pfrag->offset); 1053 if (getfrag(from, 1054 page_address(pfrag->page) + pfrag->offset, 1055 offset, copy, skb->len, skb) < 0) 1056 goto error_efault; 1057 1058 pfrag->offset += copy; 1059 skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy); 1060 skb->len += copy; 1061 skb->data_len += copy; 1062 skb->truesize += copy; 1063 atomic_add(copy, &sk->sk_wmem_alloc); 1064 } 1065 offset += copy; 1066 length -= copy; 1067 } 1068 1069 return 0; 1070 1071error_efault: 1072 err = -EFAULT; 1073error: 1074 cork->length -= length; 1075 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS); 1076 return err; 1077} 1078 1079static int ip_setup_cork(struct sock *sk, struct inet_cork *cork, 1080 struct ipcm_cookie *ipc, struct rtable **rtp) 1081{ 1082 struct ip_options_rcu *opt; 1083 struct rtable *rt; 1084 1085 /* 1086 * setup for corking. 1087 */ 1088 opt = ipc->opt; 1089 if (opt) { 1090 if (cork->opt == NULL) { 1091 cork->opt = kmalloc(sizeof(struct ip_options) + 40, 1092 sk->sk_allocation); 1093 if (unlikely(cork->opt == NULL)) 1094 return -ENOBUFS; 1095 } 1096 memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen); 1097 cork->flags |= IPCORK_OPT; 1098 cork->addr = ipc->addr; 1099 } 1100 rt = *rtp; 1101 if (unlikely(!rt)) 1102 return -EFAULT; 1103 /* 1104 * We steal reference to this route, caller should not release it 1105 */ 1106 *rtp = NULL; 1107 cork->fragsize = ip_sk_use_pmtu(sk) ? 1108 dst_mtu(&rt->dst) : rt->dst.dev->mtu; 1109 cork->dst = &rt->dst; 1110 cork->length = 0; 1111 cork->ttl = ipc->ttl; 1112 cork->tos = ipc->tos; 1113 cork->priority = ipc->priority; 1114 cork->tx_flags = ipc->tx_flags; 1115 1116 return 0; 1117} 1118 1119/* 1120 * ip_append_data() and ip_append_page() can make one large IP datagram 1121 * from many pieces of data. Each pieces will be holded on the socket 1122 * until ip_push_pending_frames() is called. Each piece can be a page 1123 * or non-page data. 1124 * 1125 * Not only UDP, other transport protocols - e.g. raw sockets - can use 1126 * this interface potentially. 1127 * 1128 * LATER: length must be adjusted by pad at tail, when it is required. 1129 */ 1130int ip_append_data(struct sock *sk, struct flowi4 *fl4, 1131 int getfrag(void *from, char *to, int offset, int len, 1132 int odd, struct sk_buff *skb), 1133 void *from, int length, int transhdrlen, 1134 struct ipcm_cookie *ipc, struct rtable **rtp, 1135 unsigned int flags) 1136{ 1137 struct inet_sock *inet = inet_sk(sk); 1138 int err; 1139 1140 if (flags&MSG_PROBE) 1141 return 0; 1142 1143 if (skb_queue_empty(&sk->sk_write_queue)) { 1144 err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp); 1145 if (err) 1146 return err; 1147 } else { 1148 transhdrlen = 0; 1149 } 1150 1151 return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base, 1152 sk_page_frag(sk), getfrag, 1153 from, length, transhdrlen, flags); 1154} 1155 1156ssize_t ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page, 1157 int offset, size_t size, int flags) 1158{ 1159 struct inet_sock *inet = inet_sk(sk); 1160 struct sk_buff *skb; 1161 struct rtable *rt; 1162 struct ip_options *opt = NULL; 1163 struct inet_cork *cork; 1164 int hh_len; 1165 int mtu; 1166 int len; 1167 int err; 1168 unsigned int maxfraglen, fragheaderlen, fraggap, maxnonfragsize; 1169 1170 if (inet->hdrincl) 1171 return -EPERM; 1172 1173 if (flags&MSG_PROBE) 1174 return 0; 1175 1176 if (skb_queue_empty(&sk->sk_write_queue)) 1177 return -EINVAL; 1178 1179 cork = &inet->cork.base; 1180 rt = (struct rtable *)cork->dst; 1181 if (cork->flags & IPCORK_OPT) 1182 opt = cork->opt; 1183 1184 if (!(rt->dst.dev->features&NETIF_F_SG)) 1185 return -EOPNOTSUPP; 1186 1187 hh_len = LL_RESERVED_SPACE(rt->dst.dev); 1188 mtu = cork->fragsize; 1189 1190 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0); 1191 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen; 1192 maxnonfragsize = ip_sk_ignore_df(sk) ? 0xFFFF : mtu; 1193 1194 if (cork->length + size > maxnonfragsize - fragheaderlen) { 1195 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport, 1196 mtu - (opt ? opt->optlen : 0)); 1197 return -EMSGSIZE; 1198 } 1199 1200 if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL) 1201 return -EINVAL; 1202 1203 cork->length += size; 1204 if ((size + skb->len > mtu) && 1205 (sk->sk_protocol == IPPROTO_UDP) && 1206 (rt->dst.dev->features & NETIF_F_UFO)) { 1207 skb_shinfo(skb)->gso_size = mtu - fragheaderlen; 1208 skb_shinfo(skb)->gso_type = SKB_GSO_UDP; 1209 } 1210 1211 1212 while (size > 0) { 1213 int i; 1214 1215 if (skb_is_gso(skb)) 1216 len = size; 1217 else { 1218 1219 /* Check if the remaining data fits into current packet. */ 1220 len = mtu - skb->len; 1221 if (len < size) 1222 len = maxfraglen - skb->len; 1223 } 1224 if (len <= 0) { 1225 struct sk_buff *skb_prev; 1226 int alloclen; 1227 1228 skb_prev = skb; 1229 fraggap = skb_prev->len - maxfraglen; 1230 1231 alloclen = fragheaderlen + hh_len + fraggap + 15; 1232 skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation); 1233 if (unlikely(!skb)) { 1234 err = -ENOBUFS; 1235 goto error; 1236 } 1237 1238 /* 1239 * Fill in the control structures 1240 */ 1241 skb->ip_summed = CHECKSUM_NONE; 1242 skb->csum = 0; 1243 skb_reserve(skb, hh_len); 1244 1245 /* 1246 * Find where to start putting bytes. 1247 */ 1248 skb_put(skb, fragheaderlen + fraggap); 1249 skb_reset_network_header(skb); 1250 skb->transport_header = (skb->network_header + 1251 fragheaderlen); 1252 if (fraggap) { 1253 skb->csum = skb_copy_and_csum_bits(skb_prev, 1254 maxfraglen, 1255 skb_transport_header(skb), 1256 fraggap, 0); 1257 skb_prev->csum = csum_sub(skb_prev->csum, 1258 skb->csum); 1259 pskb_trim_unique(skb_prev, maxfraglen); 1260 } 1261 1262 /* 1263 * Put the packet on the pending queue. 1264 */ 1265 __skb_queue_tail(&sk->sk_write_queue, skb); 1266 continue; 1267 } 1268 1269 i = skb_shinfo(skb)->nr_frags; 1270 if (len > size) 1271 len = size; 1272 if (skb_can_coalesce(skb, i, page, offset)) { 1273 skb_frag_size_add(&skb_shinfo(skb)->frags[i-1], len); 1274 } else if (i < MAX_SKB_FRAGS) { 1275 get_page(page); 1276 skb_fill_page_desc(skb, i, page, offset, len); 1277 } else { 1278 err = -EMSGSIZE; 1279 goto error; 1280 } 1281 1282 if (skb->ip_summed == CHECKSUM_NONE) { 1283 __wsum csum; 1284 csum = csum_page(page, offset, len); 1285 skb->csum = csum_block_add(skb->csum, csum, skb->len); 1286 } 1287 1288 skb->len += len; 1289 skb->data_len += len; 1290 skb->truesize += len; 1291 atomic_add(len, &sk->sk_wmem_alloc); 1292 offset += len; 1293 size -= len; 1294 } 1295 return 0; 1296 1297error: 1298 cork->length -= size; 1299 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS); 1300 return err; 1301} 1302 1303static void ip_cork_release(struct inet_cork *cork) 1304{ 1305 cork->flags &= ~IPCORK_OPT; 1306 kfree(cork->opt); 1307 cork->opt = NULL; 1308 dst_release(cork->dst); 1309 cork->dst = NULL; 1310} 1311 1312/* 1313 * Combined all pending IP fragments on the socket as one IP datagram 1314 * and push them out. 1315 */ 1316struct sk_buff *__ip_make_skb(struct sock *sk, 1317 struct flowi4 *fl4, 1318 struct sk_buff_head *queue, 1319 struct inet_cork *cork) 1320{ 1321 struct sk_buff *skb, *tmp_skb; 1322 struct sk_buff **tail_skb; 1323 struct inet_sock *inet = inet_sk(sk); 1324 struct net *net = sock_net(sk); 1325 struct ip_options *opt = NULL; 1326 struct rtable *rt = (struct rtable *)cork->dst; 1327 struct iphdr *iph; 1328 __be16 df = 0; 1329 __u8 ttl; 1330 1331 if ((skb = __skb_dequeue(queue)) == NULL) 1332 goto out; 1333 tail_skb = &(skb_shinfo(skb)->frag_list); 1334 1335 /* move skb->data to ip header from ext header */ 1336 if (skb->data < skb_network_header(skb)) 1337 __skb_pull(skb, skb_network_offset(skb)); 1338 while ((tmp_skb = __skb_dequeue(queue)) != NULL) { 1339 __skb_pull(tmp_skb, skb_network_header_len(skb)); 1340 *tail_skb = tmp_skb; 1341 tail_skb = &(tmp_skb->next); 1342 skb->len += tmp_skb->len; 1343 skb->data_len += tmp_skb->len; 1344 skb->truesize += tmp_skb->truesize; 1345 tmp_skb->destructor = NULL; 1346 tmp_skb->sk = NULL; 1347 } 1348 1349 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow 1350 * to fragment the frame generated here. No matter, what transforms 1351 * how transforms change size of the packet, it will come out. 1352 */ 1353 skb->ignore_df = ip_sk_ignore_df(sk); 1354 1355 /* DF bit is set when we want to see DF on outgoing frames. 1356 * If ignore_df is set too, we still allow to fragment this frame 1357 * locally. */ 1358 if (inet->pmtudisc == IP_PMTUDISC_DO || 1359 inet->pmtudisc == IP_PMTUDISC_PROBE || 1360 (skb->len <= dst_mtu(&rt->dst) && 1361 ip_dont_fragment(sk, &rt->dst))) 1362 df = htons(IP_DF); 1363 1364 if (cork->flags & IPCORK_OPT) 1365 opt = cork->opt; 1366 1367 if (cork->ttl != 0) 1368 ttl = cork->ttl; 1369 else if (rt->rt_type == RTN_MULTICAST) 1370 ttl = inet->mc_ttl; 1371 else 1372 ttl = ip_select_ttl(inet, &rt->dst); 1373 1374 iph = ip_hdr(skb); 1375 iph->version = 4; 1376 iph->ihl = 5; 1377 iph->tos = (cork->tos != -1) ? cork->tos : inet->tos; 1378 iph->frag_off = df; 1379 iph->ttl = ttl; 1380 iph->protocol = sk->sk_protocol; 1381 ip_copy_addrs(iph, fl4); 1382 ip_select_ident(skb, &rt->dst, sk); 1383 1384 if (opt) { 1385 iph->ihl += opt->optlen>>2; 1386 ip_options_build(skb, opt, cork->addr, rt, 0); 1387 } 1388 1389 skb->priority = (cork->tos != -1) ? cork->priority: sk->sk_priority; 1390 skb->mark = sk->sk_mark; 1391 /* 1392 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec 1393 * on dst refcount 1394 */ 1395 cork->dst = NULL; 1396 skb_dst_set(skb, &rt->dst); 1397 1398 if (iph->protocol == IPPROTO_ICMP) 1399 icmp_out_count(net, ((struct icmphdr *) 1400 skb_transport_header(skb))->type); 1401 1402 ip_cork_release(cork); 1403out: 1404 return skb; 1405} 1406 1407int ip_send_skb(struct net *net, struct sk_buff *skb) 1408{ 1409 int err; 1410 1411 err = ip_local_out(skb); 1412 if (err) { 1413 if (err > 0) 1414 err = net_xmit_errno(err); 1415 if (err) 1416 IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS); 1417 } 1418 1419 return err; 1420} 1421 1422int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4) 1423{ 1424 struct sk_buff *skb; 1425 1426 skb = ip_finish_skb(sk, fl4); 1427 if (!skb) 1428 return 0; 1429 1430 /* Netfilter gets whole the not fragmented skb. */ 1431 return ip_send_skb(sock_net(sk), skb); 1432} 1433 1434/* 1435 * Throw away all pending data on the socket. 1436 */ 1437static void __ip_flush_pending_frames(struct sock *sk, 1438 struct sk_buff_head *queue, 1439 struct inet_cork *cork) 1440{ 1441 struct sk_buff *skb; 1442 1443 while ((skb = __skb_dequeue_tail(queue)) != NULL) 1444 kfree_skb(skb); 1445 1446 ip_cork_release(cork); 1447} 1448 1449void ip_flush_pending_frames(struct sock *sk) 1450{ 1451 __ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork.base); 1452} 1453 1454struct sk_buff *ip_make_skb(struct sock *sk, 1455 struct flowi4 *fl4, 1456 int getfrag(void *from, char *to, int offset, 1457 int len, int odd, struct sk_buff *skb), 1458 void *from, int length, int transhdrlen, 1459 struct ipcm_cookie *ipc, struct rtable **rtp, 1460 unsigned int flags) 1461{ 1462 struct inet_cork cork; 1463 struct sk_buff_head queue; 1464 int err; 1465 1466 if (flags & MSG_PROBE) 1467 return NULL; 1468 1469 __skb_queue_head_init(&queue); 1470 1471 cork.flags = 0; 1472 cork.addr = 0; 1473 cork.opt = NULL; 1474 err = ip_setup_cork(sk, &cork, ipc, rtp); 1475 if (err) 1476 return ERR_PTR(err); 1477 1478 err = __ip_append_data(sk, fl4, &queue, &cork, 1479 ¤t->task_frag, getfrag, 1480 from, length, transhdrlen, flags); 1481 if (err) { 1482 __ip_flush_pending_frames(sk, &queue, &cork); 1483 return ERR_PTR(err); 1484 } 1485 1486 return __ip_make_skb(sk, fl4, &queue, &cork); 1487} 1488 1489/* 1490 * Fetch data from kernel space and fill in checksum if needed. 1491 */ 1492static int ip_reply_glue_bits(void *dptr, char *to, int offset, 1493 int len, int odd, struct sk_buff *skb) 1494{ 1495 __wsum csum; 1496 1497 csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0); 1498 skb->csum = csum_block_add(skb->csum, csum, odd); 1499 return 0; 1500} 1501 1502/* 1503 * Generic function to send a packet as reply to another packet. 1504 * Used to send some TCP resets/acks so far. 1505 * 1506 * Use a fake percpu inet socket to avoid false sharing and contention. 1507 */ 1508static DEFINE_PER_CPU(struct inet_sock, unicast_sock) = { 1509 .sk = { 1510 .__sk_common = { 1511 .skc_refcnt = ATOMIC_INIT(1), 1512 }, 1513 .sk_wmem_alloc = ATOMIC_INIT(1), 1514 .sk_allocation = GFP_ATOMIC, 1515 .sk_flags = (1UL << SOCK_USE_WRITE_QUEUE), 1516 }, 1517 .pmtudisc = IP_PMTUDISC_WANT, 1518 .uc_ttl = -1, 1519}; 1520 1521void ip_send_unicast_reply(struct net *net, struct sk_buff *skb, __be32 daddr, 1522 __be32 saddr, const struct ip_reply_arg *arg, 1523 unsigned int len) 1524{ 1525 struct ip_options_data replyopts; 1526 struct ipcm_cookie ipc; 1527 struct flowi4 fl4; 1528 struct rtable *rt = skb_rtable(skb); 1529 struct sk_buff *nskb; 1530 struct sock *sk; 1531 struct inet_sock *inet; 1532 1533 if (ip_options_echo(&replyopts.opt.opt, skb)) 1534 return; 1535 1536 ipc.addr = daddr; 1537 ipc.opt = NULL; 1538 ipc.tx_flags = 0; 1539 ipc.ttl = 0; 1540 ipc.tos = -1; 1541 1542 if (replyopts.opt.opt.optlen) { 1543 ipc.opt = &replyopts.opt; 1544 1545 if (replyopts.opt.opt.srr) 1546 daddr = replyopts.opt.opt.faddr; 1547 } 1548 1549 flowi4_init_output(&fl4, arg->bound_dev_if, 1550 IP4_REPLY_MARK(net, skb->mark), 1551 RT_TOS(arg->tos), 1552 RT_SCOPE_UNIVERSE, ip_hdr(skb)->protocol, 1553 ip_reply_arg_flowi_flags(arg), 1554 daddr, saddr, 1555 tcp_hdr(skb)->source, tcp_hdr(skb)->dest); 1556 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4)); 1557 rt = ip_route_output_key(net, &fl4); 1558 if (IS_ERR(rt)) 1559 return; 1560 1561 inet = &get_cpu_var(unicast_sock); 1562 1563 inet->tos = arg->tos; 1564 sk = &inet->sk; 1565 sk->sk_priority = skb->priority; 1566 sk->sk_protocol = ip_hdr(skb)->protocol; 1567 sk->sk_bound_dev_if = arg->bound_dev_if; 1568 sock_net_set(sk, net); 1569 __skb_queue_head_init(&sk->sk_write_queue); 1570 sk->sk_sndbuf = sysctl_wmem_default; 1571 ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base, len, 0, 1572 &ipc, &rt, MSG_DONTWAIT); 1573 nskb = skb_peek(&sk->sk_write_queue); 1574 if (nskb) { 1575 if (arg->csumoffset >= 0) 1576 *((__sum16 *)skb_transport_header(nskb) + 1577 arg->csumoffset) = csum_fold(csum_add(nskb->csum, 1578 arg->csum)); 1579 nskb->ip_summed = CHECKSUM_NONE; 1580 skb_orphan(nskb); 1581 skb_set_queue_mapping(nskb, skb_get_queue_mapping(skb)); 1582 ip_push_pending_frames(sk, &fl4); 1583 } 1584 1585 put_cpu_var(unicast_sock); 1586 1587 ip_rt_put(rt); 1588} 1589 1590void __init ip_init(void) 1591{ 1592 ip_rt_init(); 1593 inet_initpeers(); 1594 1595#if defined(CONFIG_IP_MULTICAST) 1596 igmp_mc_init(); 1597#endif 1598} 1599