ip_output.c revision ba3d8d3f9f65807763b2e0e1ea7645d74a962248
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, 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_OR_NULL(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_segs(skb, sk, skb_shinfo(skb)->gso_segs ?: 1); 434 435 /* TODO : should we use skb->sk here instead of sk ? */ 436 skb->priority = sk->sk_priority; 437 skb->mark = sk->sk_mark; 438 439 res = ip_local_out(skb); 440 rcu_read_unlock(); 441 return res; 442 443no_route: 444 rcu_read_unlock(); 445 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES); 446 kfree_skb(skb); 447 return -EHOSTUNREACH; 448} 449EXPORT_SYMBOL(ip_queue_xmit); 450 451 452static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from) 453{ 454 to->pkt_type = from->pkt_type; 455 to->priority = from->priority; 456 to->protocol = from->protocol; 457 skb_dst_drop(to); 458 skb_dst_copy(to, from); 459 to->dev = from->dev; 460 to->mark = from->mark; 461 462 /* Copy the flags to each fragment. */ 463 IPCB(to)->flags = IPCB(from)->flags; 464 465#ifdef CONFIG_NET_SCHED 466 to->tc_index = from->tc_index; 467#endif 468 nf_copy(to, from); 469#if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE) 470 to->ipvs_property = from->ipvs_property; 471#endif 472 skb_copy_secmark(to, from); 473} 474 475/* 476 * This IP datagram is too large to be sent in one piece. Break it up into 477 * smaller pieces (each of size equal to IP header plus 478 * a block of the data of the original IP data part) that will yet fit in a 479 * single device frame, and queue such a frame for sending. 480 */ 481 482int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *)) 483{ 484 struct iphdr *iph; 485 int ptr; 486 struct net_device *dev; 487 struct sk_buff *skb2; 488 unsigned int mtu, hlen, left, len, ll_rs; 489 int offset; 490 __be16 not_last_frag; 491 struct rtable *rt = skb_rtable(skb); 492 int err = 0; 493 494 dev = rt->dst.dev; 495 496 /* 497 * Point into the IP datagram header. 498 */ 499 500 iph = ip_hdr(skb); 501 502 mtu = ip_skb_dst_mtu(skb); 503 if (unlikely(((iph->frag_off & htons(IP_DF)) && !skb->ignore_df) || 504 (IPCB(skb)->frag_max_size && 505 IPCB(skb)->frag_max_size > mtu))) { 506 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); 507 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, 508 htonl(mtu)); 509 kfree_skb(skb); 510 return -EMSGSIZE; 511 } 512 513 /* 514 * Setup starting values. 515 */ 516 517 hlen = iph->ihl * 4; 518 mtu = mtu - hlen; /* Size of data space */ 519#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) 520 if (skb->nf_bridge) 521 mtu -= nf_bridge_mtu_reduction(skb); 522#endif 523 IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE; 524 525 /* When frag_list is given, use it. First, check its validity: 526 * some transformers could create wrong frag_list or break existing 527 * one, it is not prohibited. In this case fall back to copying. 528 * 529 * LATER: this step can be merged to real generation of fragments, 530 * we can switch to copy when see the first bad fragment. 531 */ 532 if (skb_has_frag_list(skb)) { 533 struct sk_buff *frag, *frag2; 534 int first_len = skb_pagelen(skb); 535 536 if (first_len - hlen > mtu || 537 ((first_len - hlen) & 7) || 538 ip_is_fragment(iph) || 539 skb_cloned(skb)) 540 goto slow_path; 541 542 skb_walk_frags(skb, frag) { 543 /* Correct geometry. */ 544 if (frag->len > mtu || 545 ((frag->len & 7) && frag->next) || 546 skb_headroom(frag) < hlen) 547 goto slow_path_clean; 548 549 /* Partially cloned skb? */ 550 if (skb_shared(frag)) 551 goto slow_path_clean; 552 553 BUG_ON(frag->sk); 554 if (skb->sk) { 555 frag->sk = skb->sk; 556 frag->destructor = sock_wfree; 557 } 558 skb->truesize -= frag->truesize; 559 } 560 561 /* Everything is OK. Generate! */ 562 563 err = 0; 564 offset = 0; 565 frag = skb_shinfo(skb)->frag_list; 566 skb_frag_list_init(skb); 567 skb->data_len = first_len - skb_headlen(skb); 568 skb->len = first_len; 569 iph->tot_len = htons(first_len); 570 iph->frag_off = htons(IP_MF); 571 ip_send_check(iph); 572 573 for (;;) { 574 /* Prepare header of the next frame, 575 * before previous one went down. */ 576 if (frag) { 577 frag->ip_summed = CHECKSUM_NONE; 578 skb_reset_transport_header(frag); 579 __skb_push(frag, hlen); 580 skb_reset_network_header(frag); 581 memcpy(skb_network_header(frag), iph, hlen); 582 iph = ip_hdr(frag); 583 iph->tot_len = htons(frag->len); 584 ip_copy_metadata(frag, skb); 585 if (offset == 0) 586 ip_options_fragment(frag); 587 offset += skb->len - hlen; 588 iph->frag_off = htons(offset>>3); 589 if (frag->next != NULL) 590 iph->frag_off |= htons(IP_MF); 591 /* Ready, complete checksum */ 592 ip_send_check(iph); 593 } 594 595 err = output(skb); 596 597 if (!err) 598 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES); 599 if (err || !frag) 600 break; 601 602 skb = frag; 603 frag = skb->next; 604 skb->next = NULL; 605 } 606 607 if (err == 0) { 608 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS); 609 return 0; 610 } 611 612 while (frag) { 613 skb = frag->next; 614 kfree_skb(frag); 615 frag = skb; 616 } 617 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); 618 return err; 619 620slow_path_clean: 621 skb_walk_frags(skb, frag2) { 622 if (frag2 == frag) 623 break; 624 frag2->sk = NULL; 625 frag2->destructor = NULL; 626 skb->truesize += frag2->truesize; 627 } 628 } 629 630slow_path: 631 /* for offloaded checksums cleanup checksum before fragmentation */ 632 if ((skb->ip_summed == CHECKSUM_PARTIAL) && skb_checksum_help(skb)) 633 goto fail; 634 iph = ip_hdr(skb); 635 636 left = skb->len - hlen; /* Space per frame */ 637 ptr = hlen; /* Where to start from */ 638 639 /* for bridged IP traffic encapsulated inside f.e. a vlan header, 640 * we need to make room for the encapsulating header 641 */ 642 ll_rs = LL_RESERVED_SPACE_EXTRA(rt->dst.dev, nf_bridge_pad(skb)); 643 644 /* 645 * Fragment the datagram. 646 */ 647 648 offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3; 649 not_last_frag = iph->frag_off & htons(IP_MF); 650 651 /* 652 * Keep copying data until we run out. 653 */ 654 655 while (left > 0) { 656 len = left; 657 /* IF: it doesn't fit, use 'mtu' - the data space left */ 658 if (len > mtu) 659 len = mtu; 660 /* IF: we are not sending up to and including the packet end 661 then align the next start on an eight byte boundary */ 662 if (len < left) { 663 len &= ~7; 664 } 665 /* 666 * Allocate buffer. 667 */ 668 669 if ((skb2 = alloc_skb(len+hlen+ll_rs, GFP_ATOMIC)) == NULL) { 670 NETDEBUG(KERN_INFO "IP: frag: no memory for new fragment!\n"); 671 err = -ENOMEM; 672 goto fail; 673 } 674 675 /* 676 * Set up data on packet 677 */ 678 679 ip_copy_metadata(skb2, skb); 680 skb_reserve(skb2, ll_rs); 681 skb_put(skb2, len + hlen); 682 skb_reset_network_header(skb2); 683 skb2->transport_header = skb2->network_header + hlen; 684 685 /* 686 * Charge the memory for the fragment to any owner 687 * it might possess 688 */ 689 690 if (skb->sk) 691 skb_set_owner_w(skb2, skb->sk); 692 693 /* 694 * Copy the packet header into the new buffer. 695 */ 696 697 skb_copy_from_linear_data(skb, skb_network_header(skb2), hlen); 698 699 /* 700 * Copy a block of the IP datagram. 701 */ 702 if (skb_copy_bits(skb, ptr, skb_transport_header(skb2), len)) 703 BUG(); 704 left -= len; 705 706 /* 707 * Fill in the new header fields. 708 */ 709 iph = ip_hdr(skb2); 710 iph->frag_off = htons((offset >> 3)); 711 712 /* ANK: dirty, but effective trick. Upgrade options only if 713 * the segment to be fragmented was THE FIRST (otherwise, 714 * options are already fixed) and make it ONCE 715 * on the initial skb, so that all the following fragments 716 * will inherit fixed options. 717 */ 718 if (offset == 0) 719 ip_options_fragment(skb); 720 721 /* 722 * Added AC : If we are fragmenting a fragment that's not the 723 * last fragment then keep MF on each bit 724 */ 725 if (left > 0 || not_last_frag) 726 iph->frag_off |= htons(IP_MF); 727 ptr += len; 728 offset += len; 729 730 /* 731 * Put this fragment into the sending queue. 732 */ 733 iph->tot_len = htons(len + hlen); 734 735 ip_send_check(iph); 736 737 err = output(skb2); 738 if (err) 739 goto fail; 740 741 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES); 742 } 743 consume_skb(skb); 744 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS); 745 return err; 746 747fail: 748 kfree_skb(skb); 749 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); 750 return err; 751} 752EXPORT_SYMBOL(ip_fragment); 753 754int 755ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb) 756{ 757 struct iovec *iov = from; 758 759 if (skb->ip_summed == CHECKSUM_PARTIAL) { 760 if (memcpy_fromiovecend(to, iov, offset, len) < 0) 761 return -EFAULT; 762 } else { 763 __wsum csum = 0; 764 if (csum_partial_copy_fromiovecend(to, iov, offset, len, &csum) < 0) 765 return -EFAULT; 766 skb->csum = csum_block_add(skb->csum, csum, odd); 767 } 768 return 0; 769} 770EXPORT_SYMBOL(ip_generic_getfrag); 771 772static inline __wsum 773csum_page(struct page *page, int offset, int copy) 774{ 775 char *kaddr; 776 __wsum csum; 777 kaddr = kmap(page); 778 csum = csum_partial(kaddr + offset, copy, 0); 779 kunmap(page); 780 return csum; 781} 782 783static inline int ip_ufo_append_data(struct sock *sk, 784 struct sk_buff_head *queue, 785 int getfrag(void *from, char *to, int offset, int len, 786 int odd, struct sk_buff *skb), 787 void *from, int length, int hh_len, int fragheaderlen, 788 int transhdrlen, int maxfraglen, unsigned int flags) 789{ 790 struct sk_buff *skb; 791 int err; 792 793 /* There is support for UDP fragmentation offload by network 794 * device, so create one single skb packet containing complete 795 * udp datagram 796 */ 797 if ((skb = skb_peek_tail(queue)) == NULL) { 798 skb = sock_alloc_send_skb(sk, 799 hh_len + fragheaderlen + transhdrlen + 20, 800 (flags & MSG_DONTWAIT), &err); 801 802 if (skb == NULL) 803 return err; 804 805 /* reserve space for Hardware header */ 806 skb_reserve(skb, hh_len); 807 808 /* create space for UDP/IP header */ 809 skb_put(skb, fragheaderlen + transhdrlen); 810 811 /* initialize network header pointer */ 812 skb_reset_network_header(skb); 813 814 /* initialize protocol header pointer */ 815 skb->transport_header = skb->network_header + fragheaderlen; 816 817 skb->csum = 0; 818 819 820 __skb_queue_tail(queue, skb); 821 } else if (skb_is_gso(skb)) { 822 goto append; 823 } 824 825 skb->ip_summed = CHECKSUM_PARTIAL; 826 /* specify the length of each IP datagram fragment */ 827 skb_shinfo(skb)->gso_size = maxfraglen - fragheaderlen; 828 skb_shinfo(skb)->gso_type = SKB_GSO_UDP; 829 830append: 831 return skb_append_datato_frags(sk, skb, getfrag, from, 832 (length - transhdrlen)); 833} 834 835static int __ip_append_data(struct sock *sk, 836 struct flowi4 *fl4, 837 struct sk_buff_head *queue, 838 struct inet_cork *cork, 839 struct page_frag *pfrag, 840 int getfrag(void *from, char *to, int offset, 841 int len, int odd, struct sk_buff *skb), 842 void *from, int length, int transhdrlen, 843 unsigned int flags) 844{ 845 struct inet_sock *inet = inet_sk(sk); 846 struct sk_buff *skb; 847 848 struct ip_options *opt = cork->opt; 849 int hh_len; 850 int exthdrlen; 851 int mtu; 852 int copy; 853 int err; 854 int offset = 0; 855 unsigned int maxfraglen, fragheaderlen, maxnonfragsize; 856 int csummode = CHECKSUM_NONE; 857 struct rtable *rt = (struct rtable *)cork->dst; 858 u32 tskey = 0; 859 860 skb = skb_peek_tail(queue); 861 862 exthdrlen = !skb ? rt->dst.header_len : 0; 863 mtu = cork->fragsize; 864 if (cork->tx_flags & SKBTX_ANY_SW_TSTAMP && 865 sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID) 866 tskey = sk->sk_tskey++; 867 868 hh_len = LL_RESERVED_SPACE(rt->dst.dev); 869 870 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0); 871 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen; 872 maxnonfragsize = ip_sk_ignore_df(sk) ? 0xFFFF : mtu; 873 874 if (cork->length + length > maxnonfragsize - fragheaderlen) { 875 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport, 876 mtu - (opt ? opt->optlen : 0)); 877 return -EMSGSIZE; 878 } 879 880 /* 881 * transhdrlen > 0 means that this is the first fragment and we wish 882 * it won't be fragmented in the future. 883 */ 884 if (transhdrlen && 885 length + fragheaderlen <= mtu && 886 rt->dst.dev->features & NETIF_F_V4_CSUM && 887 !exthdrlen) 888 csummode = CHECKSUM_PARTIAL; 889 890 cork->length += length; 891 if (((length > mtu) || (skb && skb_is_gso(skb))) && 892 (sk->sk_protocol == IPPROTO_UDP) && 893 (rt->dst.dev->features & NETIF_F_UFO) && !rt->dst.header_len) { 894 err = ip_ufo_append_data(sk, queue, getfrag, from, length, 895 hh_len, fragheaderlen, transhdrlen, 896 maxfraglen, flags); 897 if (err) 898 goto error; 899 return 0; 900 } 901 902 /* So, what's going on in the loop below? 903 * 904 * We use calculated fragment length to generate chained skb, 905 * each of segments is IP fragment ready for sending to network after 906 * adding appropriate IP header. 907 */ 908 909 if (!skb) 910 goto alloc_new_skb; 911 912 while (length > 0) { 913 /* Check if the remaining data fits into current packet. */ 914 copy = mtu - skb->len; 915 if (copy < length) 916 copy = maxfraglen - skb->len; 917 if (copy <= 0) { 918 char *data; 919 unsigned int datalen; 920 unsigned int fraglen; 921 unsigned int fraggap; 922 unsigned int alloclen; 923 struct sk_buff *skb_prev; 924alloc_new_skb: 925 skb_prev = skb; 926 if (skb_prev) 927 fraggap = skb_prev->len - maxfraglen; 928 else 929 fraggap = 0; 930 931 /* 932 * If remaining data exceeds the mtu, 933 * we know we need more fragment(s). 934 */ 935 datalen = length + fraggap; 936 if (datalen > mtu - fragheaderlen) 937 datalen = maxfraglen - fragheaderlen; 938 fraglen = datalen + fragheaderlen; 939 940 if ((flags & MSG_MORE) && 941 !(rt->dst.dev->features&NETIF_F_SG)) 942 alloclen = mtu; 943 else 944 alloclen = fraglen; 945 946 alloclen += exthdrlen; 947 948 /* The last fragment gets additional space at tail. 949 * Note, with MSG_MORE we overallocate on fragments, 950 * because we have no idea what fragment will be 951 * the last. 952 */ 953 if (datalen == length + fraggap) 954 alloclen += rt->dst.trailer_len; 955 956 if (transhdrlen) { 957 skb = sock_alloc_send_skb(sk, 958 alloclen + hh_len + 15, 959 (flags & MSG_DONTWAIT), &err); 960 } else { 961 skb = NULL; 962 if (atomic_read(&sk->sk_wmem_alloc) <= 963 2 * sk->sk_sndbuf) 964 skb = sock_wmalloc(sk, 965 alloclen + hh_len + 15, 1, 966 sk->sk_allocation); 967 if (unlikely(skb == NULL)) 968 err = -ENOBUFS; 969 } 970 if (skb == NULL) 971 goto error; 972 973 /* 974 * Fill in the control structures 975 */ 976 skb->ip_summed = csummode; 977 skb->csum = 0; 978 skb_reserve(skb, hh_len); 979 980 /* only the initial fragment is time stamped */ 981 skb_shinfo(skb)->tx_flags = cork->tx_flags; 982 cork->tx_flags = 0; 983 skb_shinfo(skb)->tskey = tskey; 984 tskey = 0; 985 986 /* 987 * Find where to start putting bytes. 988 */ 989 data = skb_put(skb, fraglen + exthdrlen); 990 skb_set_network_header(skb, exthdrlen); 991 skb->transport_header = (skb->network_header + 992 fragheaderlen); 993 data += fragheaderlen + exthdrlen; 994 995 if (fraggap) { 996 skb->csum = skb_copy_and_csum_bits( 997 skb_prev, maxfraglen, 998 data + transhdrlen, fraggap, 0); 999 skb_prev->csum = csum_sub(skb_prev->csum, 1000 skb->csum); 1001 data += fraggap; 1002 pskb_trim_unique(skb_prev, maxfraglen); 1003 } 1004 1005 copy = datalen - transhdrlen - fraggap; 1006 if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) { 1007 err = -EFAULT; 1008 kfree_skb(skb); 1009 goto error; 1010 } 1011 1012 offset += copy; 1013 length -= datalen - fraggap; 1014 transhdrlen = 0; 1015 exthdrlen = 0; 1016 csummode = CHECKSUM_NONE; 1017 1018 /* 1019 * Put the packet on the pending queue. 1020 */ 1021 __skb_queue_tail(queue, skb); 1022 continue; 1023 } 1024 1025 if (copy > length) 1026 copy = length; 1027 1028 if (!(rt->dst.dev->features&NETIF_F_SG)) { 1029 unsigned int off; 1030 1031 off = skb->len; 1032 if (getfrag(from, skb_put(skb, copy), 1033 offset, copy, off, skb) < 0) { 1034 __skb_trim(skb, off); 1035 err = -EFAULT; 1036 goto error; 1037 } 1038 } else { 1039 int i = skb_shinfo(skb)->nr_frags; 1040 1041 err = -ENOMEM; 1042 if (!sk_page_frag_refill(sk, pfrag)) 1043 goto error; 1044 1045 if (!skb_can_coalesce(skb, i, pfrag->page, 1046 pfrag->offset)) { 1047 err = -EMSGSIZE; 1048 if (i == MAX_SKB_FRAGS) 1049 goto error; 1050 1051 __skb_fill_page_desc(skb, i, pfrag->page, 1052 pfrag->offset, 0); 1053 skb_shinfo(skb)->nr_frags = ++i; 1054 get_page(pfrag->page); 1055 } 1056 copy = min_t(int, copy, pfrag->size - pfrag->offset); 1057 if (getfrag(from, 1058 page_address(pfrag->page) + pfrag->offset, 1059 offset, copy, skb->len, skb) < 0) 1060 goto error_efault; 1061 1062 pfrag->offset += copy; 1063 skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy); 1064 skb->len += copy; 1065 skb->data_len += copy; 1066 skb->truesize += copy; 1067 atomic_add(copy, &sk->sk_wmem_alloc); 1068 } 1069 offset += copy; 1070 length -= copy; 1071 } 1072 1073 return 0; 1074 1075error_efault: 1076 err = -EFAULT; 1077error: 1078 cork->length -= length; 1079 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS); 1080 return err; 1081} 1082 1083static int ip_setup_cork(struct sock *sk, struct inet_cork *cork, 1084 struct ipcm_cookie *ipc, struct rtable **rtp) 1085{ 1086 struct ip_options_rcu *opt; 1087 struct rtable *rt; 1088 1089 /* 1090 * setup for corking. 1091 */ 1092 opt = ipc->opt; 1093 if (opt) { 1094 if (cork->opt == NULL) { 1095 cork->opt = kmalloc(sizeof(struct ip_options) + 40, 1096 sk->sk_allocation); 1097 if (unlikely(cork->opt == NULL)) 1098 return -ENOBUFS; 1099 } 1100 memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen); 1101 cork->flags |= IPCORK_OPT; 1102 cork->addr = ipc->addr; 1103 } 1104 rt = *rtp; 1105 if (unlikely(!rt)) 1106 return -EFAULT; 1107 /* 1108 * We steal reference to this route, caller should not release it 1109 */ 1110 *rtp = NULL; 1111 cork->fragsize = ip_sk_use_pmtu(sk) ? 1112 dst_mtu(&rt->dst) : rt->dst.dev->mtu; 1113 cork->dst = &rt->dst; 1114 cork->length = 0; 1115 cork->ttl = ipc->ttl; 1116 cork->tos = ipc->tos; 1117 cork->priority = ipc->priority; 1118 cork->tx_flags = ipc->tx_flags; 1119 1120 return 0; 1121} 1122 1123/* 1124 * ip_append_data() and ip_append_page() can make one large IP datagram 1125 * from many pieces of data. Each pieces will be holded on the socket 1126 * until ip_push_pending_frames() is called. Each piece can be a page 1127 * or non-page data. 1128 * 1129 * Not only UDP, other transport protocols - e.g. raw sockets - can use 1130 * this interface potentially. 1131 * 1132 * LATER: length must be adjusted by pad at tail, when it is required. 1133 */ 1134int ip_append_data(struct sock *sk, struct flowi4 *fl4, 1135 int getfrag(void *from, char *to, int offset, int len, 1136 int odd, struct sk_buff *skb), 1137 void *from, int length, int transhdrlen, 1138 struct ipcm_cookie *ipc, struct rtable **rtp, 1139 unsigned int flags) 1140{ 1141 struct inet_sock *inet = inet_sk(sk); 1142 int err; 1143 1144 if (flags&MSG_PROBE) 1145 return 0; 1146 1147 if (skb_queue_empty(&sk->sk_write_queue)) { 1148 err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp); 1149 if (err) 1150 return err; 1151 } else { 1152 transhdrlen = 0; 1153 } 1154 1155 return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base, 1156 sk_page_frag(sk), getfrag, 1157 from, length, transhdrlen, flags); 1158} 1159 1160ssize_t ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page, 1161 int offset, size_t size, int flags) 1162{ 1163 struct inet_sock *inet = inet_sk(sk); 1164 struct sk_buff *skb; 1165 struct rtable *rt; 1166 struct ip_options *opt = NULL; 1167 struct inet_cork *cork; 1168 int hh_len; 1169 int mtu; 1170 int len; 1171 int err; 1172 unsigned int maxfraglen, fragheaderlen, fraggap, maxnonfragsize; 1173 1174 if (inet->hdrincl) 1175 return -EPERM; 1176 1177 if (flags&MSG_PROBE) 1178 return 0; 1179 1180 if (skb_queue_empty(&sk->sk_write_queue)) 1181 return -EINVAL; 1182 1183 cork = &inet->cork.base; 1184 rt = (struct rtable *)cork->dst; 1185 if (cork->flags & IPCORK_OPT) 1186 opt = cork->opt; 1187 1188 if (!(rt->dst.dev->features&NETIF_F_SG)) 1189 return -EOPNOTSUPP; 1190 1191 hh_len = LL_RESERVED_SPACE(rt->dst.dev); 1192 mtu = cork->fragsize; 1193 1194 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0); 1195 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen; 1196 maxnonfragsize = ip_sk_ignore_df(sk) ? 0xFFFF : mtu; 1197 1198 if (cork->length + size > maxnonfragsize - fragheaderlen) { 1199 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport, 1200 mtu - (opt ? opt->optlen : 0)); 1201 return -EMSGSIZE; 1202 } 1203 1204 if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL) 1205 return -EINVAL; 1206 1207 cork->length += size; 1208 if ((size + skb->len > mtu) && 1209 (sk->sk_protocol == IPPROTO_UDP) && 1210 (rt->dst.dev->features & NETIF_F_UFO)) { 1211 skb_shinfo(skb)->gso_size = mtu - fragheaderlen; 1212 skb_shinfo(skb)->gso_type = SKB_GSO_UDP; 1213 } 1214 1215 1216 while (size > 0) { 1217 int i; 1218 1219 if (skb_is_gso(skb)) 1220 len = size; 1221 else { 1222 1223 /* Check if the remaining data fits into current packet. */ 1224 len = mtu - skb->len; 1225 if (len < size) 1226 len = maxfraglen - skb->len; 1227 } 1228 if (len <= 0) { 1229 struct sk_buff *skb_prev; 1230 int alloclen; 1231 1232 skb_prev = skb; 1233 fraggap = skb_prev->len - maxfraglen; 1234 1235 alloclen = fragheaderlen + hh_len + fraggap + 15; 1236 skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation); 1237 if (unlikely(!skb)) { 1238 err = -ENOBUFS; 1239 goto error; 1240 } 1241 1242 /* 1243 * Fill in the control structures 1244 */ 1245 skb->ip_summed = CHECKSUM_NONE; 1246 skb->csum = 0; 1247 skb_reserve(skb, hh_len); 1248 1249 /* 1250 * Find where to start putting bytes. 1251 */ 1252 skb_put(skb, fragheaderlen + fraggap); 1253 skb_reset_network_header(skb); 1254 skb->transport_header = (skb->network_header + 1255 fragheaderlen); 1256 if (fraggap) { 1257 skb->csum = skb_copy_and_csum_bits(skb_prev, 1258 maxfraglen, 1259 skb_transport_header(skb), 1260 fraggap, 0); 1261 skb_prev->csum = csum_sub(skb_prev->csum, 1262 skb->csum); 1263 pskb_trim_unique(skb_prev, maxfraglen); 1264 } 1265 1266 /* 1267 * Put the packet on the pending queue. 1268 */ 1269 __skb_queue_tail(&sk->sk_write_queue, skb); 1270 continue; 1271 } 1272 1273 i = skb_shinfo(skb)->nr_frags; 1274 if (len > size) 1275 len = size; 1276 if (skb_can_coalesce(skb, i, page, offset)) { 1277 skb_frag_size_add(&skb_shinfo(skb)->frags[i-1], len); 1278 } else if (i < MAX_SKB_FRAGS) { 1279 get_page(page); 1280 skb_fill_page_desc(skb, i, page, offset, len); 1281 } else { 1282 err = -EMSGSIZE; 1283 goto error; 1284 } 1285 1286 if (skb->ip_summed == CHECKSUM_NONE) { 1287 __wsum csum; 1288 csum = csum_page(page, offset, len); 1289 skb->csum = csum_block_add(skb->csum, csum, skb->len); 1290 } 1291 1292 skb->len += len; 1293 skb->data_len += len; 1294 skb->truesize += len; 1295 atomic_add(len, &sk->sk_wmem_alloc); 1296 offset += len; 1297 size -= len; 1298 } 1299 return 0; 1300 1301error: 1302 cork->length -= size; 1303 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS); 1304 return err; 1305} 1306 1307static void ip_cork_release(struct inet_cork *cork) 1308{ 1309 cork->flags &= ~IPCORK_OPT; 1310 kfree(cork->opt); 1311 cork->opt = NULL; 1312 dst_release(cork->dst); 1313 cork->dst = NULL; 1314} 1315 1316/* 1317 * Combined all pending IP fragments on the socket as one IP datagram 1318 * and push them out. 1319 */ 1320struct sk_buff *__ip_make_skb(struct sock *sk, 1321 struct flowi4 *fl4, 1322 struct sk_buff_head *queue, 1323 struct inet_cork *cork) 1324{ 1325 struct sk_buff *skb, *tmp_skb; 1326 struct sk_buff **tail_skb; 1327 struct inet_sock *inet = inet_sk(sk); 1328 struct net *net = sock_net(sk); 1329 struct ip_options *opt = NULL; 1330 struct rtable *rt = (struct rtable *)cork->dst; 1331 struct iphdr *iph; 1332 __be16 df = 0; 1333 __u8 ttl; 1334 1335 if ((skb = __skb_dequeue(queue)) == NULL) 1336 goto out; 1337 tail_skb = &(skb_shinfo(skb)->frag_list); 1338 1339 /* move skb->data to ip header from ext header */ 1340 if (skb->data < skb_network_header(skb)) 1341 __skb_pull(skb, skb_network_offset(skb)); 1342 while ((tmp_skb = __skb_dequeue(queue)) != NULL) { 1343 __skb_pull(tmp_skb, skb_network_header_len(skb)); 1344 *tail_skb = tmp_skb; 1345 tail_skb = &(tmp_skb->next); 1346 skb->len += tmp_skb->len; 1347 skb->data_len += tmp_skb->len; 1348 skb->truesize += tmp_skb->truesize; 1349 tmp_skb->destructor = NULL; 1350 tmp_skb->sk = NULL; 1351 } 1352 1353 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow 1354 * to fragment the frame generated here. No matter, what transforms 1355 * how transforms change size of the packet, it will come out. 1356 */ 1357 skb->ignore_df = ip_sk_ignore_df(sk); 1358 1359 /* DF bit is set when we want to see DF on outgoing frames. 1360 * If ignore_df is set too, we still allow to fragment this frame 1361 * locally. */ 1362 if (inet->pmtudisc == IP_PMTUDISC_DO || 1363 inet->pmtudisc == IP_PMTUDISC_PROBE || 1364 (skb->len <= dst_mtu(&rt->dst) && 1365 ip_dont_fragment(sk, &rt->dst))) 1366 df = htons(IP_DF); 1367 1368 if (cork->flags & IPCORK_OPT) 1369 opt = cork->opt; 1370 1371 if (cork->ttl != 0) 1372 ttl = cork->ttl; 1373 else if (rt->rt_type == RTN_MULTICAST) 1374 ttl = inet->mc_ttl; 1375 else 1376 ttl = ip_select_ttl(inet, &rt->dst); 1377 1378 iph = ip_hdr(skb); 1379 iph->version = 4; 1380 iph->ihl = 5; 1381 iph->tos = (cork->tos != -1) ? cork->tos : inet->tos; 1382 iph->frag_off = df; 1383 iph->ttl = ttl; 1384 iph->protocol = sk->sk_protocol; 1385 ip_copy_addrs(iph, fl4); 1386 ip_select_ident(skb, sk); 1387 1388 if (opt) { 1389 iph->ihl += opt->optlen>>2; 1390 ip_options_build(skb, opt, cork->addr, rt, 0); 1391 } 1392 1393 skb->priority = (cork->tos != -1) ? cork->priority: sk->sk_priority; 1394 skb->mark = sk->sk_mark; 1395 /* 1396 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec 1397 * on dst refcount 1398 */ 1399 cork->dst = NULL; 1400 skb_dst_set(skb, &rt->dst); 1401 1402 if (iph->protocol == IPPROTO_ICMP) 1403 icmp_out_count(net, ((struct icmphdr *) 1404 skb_transport_header(skb))->type); 1405 1406 ip_cork_release(cork); 1407out: 1408 return skb; 1409} 1410 1411int ip_send_skb(struct net *net, struct sk_buff *skb) 1412{ 1413 int err; 1414 1415 err = ip_local_out(skb); 1416 if (err) { 1417 if (err > 0) 1418 err = net_xmit_errno(err); 1419 if (err) 1420 IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS); 1421 } 1422 1423 return err; 1424} 1425 1426int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4) 1427{ 1428 struct sk_buff *skb; 1429 1430 skb = ip_finish_skb(sk, fl4); 1431 if (!skb) 1432 return 0; 1433 1434 /* Netfilter gets whole the not fragmented skb. */ 1435 return ip_send_skb(sock_net(sk), skb); 1436} 1437 1438/* 1439 * Throw away all pending data on the socket. 1440 */ 1441static void __ip_flush_pending_frames(struct sock *sk, 1442 struct sk_buff_head *queue, 1443 struct inet_cork *cork) 1444{ 1445 struct sk_buff *skb; 1446 1447 while ((skb = __skb_dequeue_tail(queue)) != NULL) 1448 kfree_skb(skb); 1449 1450 ip_cork_release(cork); 1451} 1452 1453void ip_flush_pending_frames(struct sock *sk) 1454{ 1455 __ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork.base); 1456} 1457 1458struct sk_buff *ip_make_skb(struct sock *sk, 1459 struct flowi4 *fl4, 1460 int getfrag(void *from, char *to, int offset, 1461 int len, int odd, struct sk_buff *skb), 1462 void *from, int length, int transhdrlen, 1463 struct ipcm_cookie *ipc, struct rtable **rtp, 1464 unsigned int flags) 1465{ 1466 struct inet_cork cork; 1467 struct sk_buff_head queue; 1468 int err; 1469 1470 if (flags & MSG_PROBE) 1471 return NULL; 1472 1473 __skb_queue_head_init(&queue); 1474 1475 cork.flags = 0; 1476 cork.addr = 0; 1477 cork.opt = NULL; 1478 err = ip_setup_cork(sk, &cork, ipc, rtp); 1479 if (err) 1480 return ERR_PTR(err); 1481 1482 err = __ip_append_data(sk, fl4, &queue, &cork, 1483 ¤t->task_frag, getfrag, 1484 from, length, transhdrlen, flags); 1485 if (err) { 1486 __ip_flush_pending_frames(sk, &queue, &cork); 1487 return ERR_PTR(err); 1488 } 1489 1490 return __ip_make_skb(sk, fl4, &queue, &cork); 1491} 1492 1493/* 1494 * Fetch data from kernel space and fill in checksum if needed. 1495 */ 1496static int ip_reply_glue_bits(void *dptr, char *to, int offset, 1497 int len, int odd, struct sk_buff *skb) 1498{ 1499 __wsum csum; 1500 1501 csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0); 1502 skb->csum = csum_block_add(skb->csum, csum, odd); 1503 return 0; 1504} 1505 1506/* 1507 * Generic function to send a packet as reply to another packet. 1508 * Used to send some TCP resets/acks so far. 1509 * 1510 * Use a fake percpu inet socket to avoid false sharing and contention. 1511 */ 1512static DEFINE_PER_CPU(struct inet_sock, unicast_sock) = { 1513 .sk = { 1514 .__sk_common = { 1515 .skc_refcnt = ATOMIC_INIT(1), 1516 }, 1517 .sk_wmem_alloc = ATOMIC_INIT(1), 1518 .sk_allocation = GFP_ATOMIC, 1519 .sk_flags = (1UL << SOCK_USE_WRITE_QUEUE), 1520 }, 1521 .pmtudisc = IP_PMTUDISC_WANT, 1522 .uc_ttl = -1, 1523}; 1524 1525void ip_send_unicast_reply(struct net *net, struct sk_buff *skb, 1526 const struct ip_options *sopt, 1527 __be32 daddr, __be32 saddr, 1528 const struct ip_reply_arg *arg, 1529 unsigned int len) 1530{ 1531 struct ip_options_data replyopts; 1532 struct ipcm_cookie ipc; 1533 struct flowi4 fl4; 1534 struct rtable *rt = skb_rtable(skb); 1535 struct sk_buff *nskb; 1536 struct sock *sk; 1537 struct inet_sock *inet; 1538 int err; 1539 1540 if (__ip_options_echo(&replyopts.opt.opt, skb, sopt)) 1541 return; 1542 1543 ipc.addr = daddr; 1544 ipc.opt = NULL; 1545 ipc.tx_flags = 0; 1546 ipc.ttl = 0; 1547 ipc.tos = -1; 1548 1549 if (replyopts.opt.opt.optlen) { 1550 ipc.opt = &replyopts.opt; 1551 1552 if (replyopts.opt.opt.srr) 1553 daddr = replyopts.opt.opt.faddr; 1554 } 1555 1556 flowi4_init_output(&fl4, arg->bound_dev_if, 1557 IP4_REPLY_MARK(net, skb->mark), 1558 RT_TOS(arg->tos), 1559 RT_SCOPE_UNIVERSE, ip_hdr(skb)->protocol, 1560 ip_reply_arg_flowi_flags(arg), 1561 daddr, saddr, 1562 tcp_hdr(skb)->source, tcp_hdr(skb)->dest, 1563 arg->uid); 1564 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4)); 1565 rt = ip_route_output_key(net, &fl4); 1566 if (IS_ERR(rt)) 1567 return; 1568 1569 inet = &get_cpu_var(unicast_sock); 1570 1571 inet->tos = arg->tos; 1572 sk = &inet->sk; 1573 sk->sk_priority = skb->priority; 1574 sk->sk_protocol = ip_hdr(skb)->protocol; 1575 sk->sk_bound_dev_if = arg->bound_dev_if; 1576 sock_net_set(sk, net); 1577 __skb_queue_head_init(&sk->sk_write_queue); 1578 sk->sk_sndbuf = sysctl_wmem_default; 1579 err = ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base, 1580 len, 0, &ipc, &rt, MSG_DONTWAIT); 1581 if (unlikely(err)) { 1582 ip_flush_pending_frames(sk); 1583 goto out; 1584 } 1585 1586 nskb = skb_peek(&sk->sk_write_queue); 1587 if (nskb) { 1588 if (arg->csumoffset >= 0) 1589 *((__sum16 *)skb_transport_header(nskb) + 1590 arg->csumoffset) = csum_fold(csum_add(nskb->csum, 1591 arg->csum)); 1592 nskb->ip_summed = CHECKSUM_NONE; 1593 skb_orphan(nskb); 1594 skb_set_queue_mapping(nskb, skb_get_queue_mapping(skb)); 1595 ip_push_pending_frames(sk, &fl4); 1596 } 1597out: 1598 put_cpu_var(unicast_sock); 1599 1600 ip_rt_put(rt); 1601} 1602 1603void __init ip_init(void) 1604{ 1605 ip_rt_init(); 1606 inet_initpeers(); 1607 1608#if defined(CONFIG_IP_MULTICAST) 1609 igmp_mc_init(); 1610#endif 1611} 1612