ip_output.c revision 3a7c384ffd57ef5fbd95f48edaa2ca4eb3d9f2ee
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. */ 87__inline__ void ip_send_check(struct iphdr *iph) 88{ 89 iph->check = 0; 90 iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl); 91} 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(struct sk_buff *skb) 105{ 106 int err; 107 108 err = __ip_local_out(skb); 109 if (likely(err == 1)) 110 err = dst_output(skb); 111 112 return err; 113} 114EXPORT_SYMBOL_GPL(ip_local_out); 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(iph, &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 = rt->rt_gateway ? rt->rt_gateway : 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 inline int ip_skb_dst_mtu(struct sk_buff *skb) 215{ 216 struct inet_sock *inet = skb->sk ? inet_sk(skb->sk) : NULL; 217 218 return (inet && inet->pmtudisc == IP_PMTUDISC_PROBE) ? 219 skb_dst(skb)->dev->mtu : dst_mtu(skb_dst(skb)); 220} 221 222static int ip_finish_output(struct sk_buff *skb) 223{ 224#if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM) 225 /* Policy lookup after SNAT yielded a new policy */ 226 if (skb_dst(skb)->xfrm != NULL) { 227 IPCB(skb)->flags |= IPSKB_REROUTED; 228 return dst_output(skb); 229 } 230#endif 231 if (skb->len > ip_skb_dst_mtu(skb) && !skb_is_gso(skb)) 232 return ip_fragment(skb, ip_finish_output2); 233 else 234 return ip_finish_output2(skb); 235} 236 237int ip_mc_output(struct sk_buff *skb) 238{ 239 struct sock *sk = skb->sk; 240 struct rtable *rt = skb_rtable(skb); 241 struct net_device *dev = rt->dst.dev; 242 243 /* 244 * If the indicated interface is up and running, send the packet. 245 */ 246 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len); 247 248 skb->dev = dev; 249 skb->protocol = htons(ETH_P_IP); 250 251 /* 252 * Multicasts are looped back for other local users 253 */ 254 255 if (rt->rt_flags&RTCF_MULTICAST) { 256 if (sk_mc_loop(sk) 257#ifdef CONFIG_IP_MROUTE 258 /* Small optimization: do not loopback not local frames, 259 which returned after forwarding; they will be dropped 260 by ip_mr_input in any case. 261 Note, that local frames are looped back to be delivered 262 to local recipients. 263 264 This check is duplicated in ip_mr_input at the moment. 265 */ 266 && 267 ((rt->rt_flags & RTCF_LOCAL) || 268 !(IPCB(skb)->flags & IPSKB_FORWARDED)) 269#endif 270 ) { 271 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC); 272 if (newskb) 273 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, 274 newskb, NULL, newskb->dev, 275 dev_loopback_xmit); 276 } 277 278 /* Multicasts with ttl 0 must not go beyond the host */ 279 280 if (ip_hdr(skb)->ttl == 0) { 281 kfree_skb(skb); 282 return 0; 283 } 284 } 285 286 if (rt->rt_flags&RTCF_BROADCAST) { 287 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC); 288 if (newskb) 289 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, newskb, 290 NULL, newskb->dev, dev_loopback_xmit); 291 } 292 293 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb, NULL, 294 skb->dev, ip_finish_output, 295 !(IPCB(skb)->flags & IPSKB_REROUTED)); 296} 297 298int ip_output(struct sk_buff *skb) 299{ 300 struct net_device *dev = skb_dst(skb)->dev; 301 302 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len); 303 304 skb->dev = dev; 305 skb->protocol = htons(ETH_P_IP); 306 307 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb, NULL, dev, 308 ip_finish_output, 309 !(IPCB(skb)->flags & IPSKB_REROUTED)); 310} 311 312/* 313 * copy saddr and daddr, possibly using 64bit load/stores 314 * Equivalent to : 315 * iph->saddr = fl4->saddr; 316 * iph->daddr = fl4->daddr; 317 */ 318static void ip_copy_addrs(struct iphdr *iph, const struct flowi4 *fl4) 319{ 320 BUILD_BUG_ON(offsetof(typeof(*fl4), daddr) != 321 offsetof(typeof(*fl4), saddr) + sizeof(fl4->saddr)); 322 memcpy(&iph->saddr, &fl4->saddr, 323 sizeof(fl4->saddr) + sizeof(fl4->daddr)); 324} 325 326int ip_queue_xmit(struct sk_buff *skb, struct flowi *fl) 327{ 328 struct sock *sk = skb->sk; 329 struct inet_sock *inet = inet_sk(sk); 330 struct ip_options_rcu *inet_opt; 331 struct flowi4 *fl4; 332 struct rtable *rt; 333 struct iphdr *iph; 334 int res; 335 336 /* Skip all of this if the packet is already routed, 337 * f.e. by something like SCTP. 338 */ 339 rcu_read_lock(); 340 inet_opt = rcu_dereference(inet->inet_opt); 341 fl4 = &fl->u.ip4; 342 rt = skb_rtable(skb); 343 if (rt != NULL) 344 goto packet_routed; 345 346 /* Make sure we can route this packet. */ 347 rt = (struct rtable *)__sk_dst_check(sk, 0); 348 if (rt == NULL) { 349 __be32 daddr; 350 351 /* Use correct destination address if we have options. */ 352 daddr = inet->inet_daddr; 353 if (inet_opt && inet_opt->opt.srr) 354 daddr = inet_opt->opt.faddr; 355 356 /* If this fails, retransmit mechanism of transport layer will 357 * keep trying until route appears or the connection times 358 * itself out. 359 */ 360 rt = ip_route_output_ports(sock_net(sk), fl4, sk, 361 daddr, inet->inet_saddr, 362 inet->inet_dport, 363 inet->inet_sport, 364 sk->sk_protocol, 365 RT_CONN_FLAGS(sk), 366 sk->sk_bound_dev_if); 367 if (IS_ERR(rt)) 368 goto no_route; 369 sk_setup_caps(sk, &rt->dst); 370 } 371 skb_dst_set_noref(skb, &rt->dst); 372 373packet_routed: 374 if (inet_opt && inet_opt->opt.is_strictroute && rt->rt_gateway) 375 goto no_route; 376 377 /* OK, we know where to send it, allocate and build IP header. */ 378 skb_push(skb, sizeof(struct iphdr) + (inet_opt ? inet_opt->opt.optlen : 0)); 379 skb_reset_network_header(skb); 380 iph = ip_hdr(skb); 381 *((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (inet->tos & 0xff)); 382 if (ip_dont_fragment(sk, &rt->dst) && !skb->local_df) 383 iph->frag_off = htons(IP_DF); 384 else 385 iph->frag_off = 0; 386 iph->ttl = ip_select_ttl(inet, &rt->dst); 387 iph->protocol = sk->sk_protocol; 388 ip_copy_addrs(iph, fl4); 389 390 /* Transport layer set skb->h.foo itself. */ 391 392 if (inet_opt && inet_opt->opt.optlen) { 393 iph->ihl += inet_opt->opt.optlen >> 2; 394 ip_options_build(skb, &inet_opt->opt, inet->inet_daddr, rt, 0); 395 } 396 397 ip_select_ident_more(iph, &rt->dst, sk, 398 (skb_shinfo(skb)->gso_segs ?: 1) - 1); 399 400 skb->priority = sk->sk_priority; 401 skb->mark = sk->sk_mark; 402 403 res = ip_local_out(skb); 404 rcu_read_unlock(); 405 return res; 406 407no_route: 408 rcu_read_unlock(); 409 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES); 410 kfree_skb(skb); 411 return -EHOSTUNREACH; 412} 413EXPORT_SYMBOL(ip_queue_xmit); 414 415 416static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from) 417{ 418 to->pkt_type = from->pkt_type; 419 to->priority = from->priority; 420 to->protocol = from->protocol; 421 skb_dst_drop(to); 422 skb_dst_copy(to, from); 423 to->dev = from->dev; 424 to->mark = from->mark; 425 426 /* Copy the flags to each fragment. */ 427 IPCB(to)->flags = IPCB(from)->flags; 428 429#ifdef CONFIG_NET_SCHED 430 to->tc_index = from->tc_index; 431#endif 432 nf_copy(to, from); 433#if defined(CONFIG_NETFILTER_XT_TARGET_TRACE) || \ 434 defined(CONFIG_NETFILTER_XT_TARGET_TRACE_MODULE) 435 to->nf_trace = from->nf_trace; 436#endif 437#if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE) 438 to->ipvs_property = from->ipvs_property; 439#endif 440 skb_copy_secmark(to, from); 441} 442 443/* 444 * This IP datagram is too large to be sent in one piece. Break it up into 445 * smaller pieces (each of size equal to IP header plus 446 * a block of the data of the original IP data part) that will yet fit in a 447 * single device frame, and queue such a frame for sending. 448 */ 449 450int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *)) 451{ 452 struct iphdr *iph; 453 int ptr; 454 struct net_device *dev; 455 struct sk_buff *skb2; 456 unsigned int mtu, hlen, left, len, ll_rs; 457 int offset; 458 __be16 not_last_frag; 459 struct rtable *rt = skb_rtable(skb); 460 int err = 0; 461 462 dev = rt->dst.dev; 463 464 /* 465 * Point into the IP datagram header. 466 */ 467 468 iph = ip_hdr(skb); 469 470 if (unlikely((iph->frag_off & htons(IP_DF)) && !skb->local_df)) { 471 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); 472 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, 473 htonl(ip_skb_dst_mtu(skb))); 474 kfree_skb(skb); 475 return -EMSGSIZE; 476 } 477 478 /* 479 * Setup starting values. 480 */ 481 482 hlen = iph->ihl * 4; 483 mtu = dst_mtu(&rt->dst) - hlen; /* Size of data space */ 484#ifdef CONFIG_BRIDGE_NETFILTER 485 if (skb->nf_bridge) 486 mtu -= nf_bridge_mtu_reduction(skb); 487#endif 488 IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE; 489 490 /* When frag_list is given, use it. First, check its validity: 491 * some transformers could create wrong frag_list or break existing 492 * one, it is not prohibited. In this case fall back to copying. 493 * 494 * LATER: this step can be merged to real generation of fragments, 495 * we can switch to copy when see the first bad fragment. 496 */ 497 if (skb_has_frag_list(skb)) { 498 struct sk_buff *frag, *frag2; 499 int first_len = skb_pagelen(skb); 500 501 if (first_len - hlen > mtu || 502 ((first_len - hlen) & 7) || 503 ip_is_fragment(iph) || 504 skb_cloned(skb)) 505 goto slow_path; 506 507 skb_walk_frags(skb, frag) { 508 /* Correct geometry. */ 509 if (frag->len > mtu || 510 ((frag->len & 7) && frag->next) || 511 skb_headroom(frag) < hlen) 512 goto slow_path_clean; 513 514 /* Partially cloned skb? */ 515 if (skb_shared(frag)) 516 goto slow_path_clean; 517 518 BUG_ON(frag->sk); 519 if (skb->sk) { 520 frag->sk = skb->sk; 521 frag->destructor = sock_wfree; 522 } 523 skb->truesize -= frag->truesize; 524 } 525 526 /* Everything is OK. Generate! */ 527 528 err = 0; 529 offset = 0; 530 frag = skb_shinfo(skb)->frag_list; 531 skb_frag_list_init(skb); 532 skb->data_len = first_len - skb_headlen(skb); 533 skb->len = first_len; 534 iph->tot_len = htons(first_len); 535 iph->frag_off = htons(IP_MF); 536 ip_send_check(iph); 537 538 for (;;) { 539 /* Prepare header of the next frame, 540 * before previous one went down. */ 541 if (frag) { 542 frag->ip_summed = CHECKSUM_NONE; 543 skb_reset_transport_header(frag); 544 __skb_push(frag, hlen); 545 skb_reset_network_header(frag); 546 memcpy(skb_network_header(frag), iph, hlen); 547 iph = ip_hdr(frag); 548 iph->tot_len = htons(frag->len); 549 ip_copy_metadata(frag, skb); 550 if (offset == 0) 551 ip_options_fragment(frag); 552 offset += skb->len - hlen; 553 iph->frag_off = htons(offset>>3); 554 if (frag->next != NULL) 555 iph->frag_off |= htons(IP_MF); 556 /* Ready, complete checksum */ 557 ip_send_check(iph); 558 } 559 560 err = output(skb); 561 562 if (!err) 563 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES); 564 if (err || !frag) 565 break; 566 567 skb = frag; 568 frag = skb->next; 569 skb->next = NULL; 570 } 571 572 if (err == 0) { 573 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS); 574 return 0; 575 } 576 577 while (frag) { 578 skb = frag->next; 579 kfree_skb(frag); 580 frag = skb; 581 } 582 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); 583 return err; 584 585slow_path_clean: 586 skb_walk_frags(skb, frag2) { 587 if (frag2 == frag) 588 break; 589 frag2->sk = NULL; 590 frag2->destructor = NULL; 591 skb->truesize += frag2->truesize; 592 } 593 } 594 595slow_path: 596 left = skb->len - hlen; /* Space per frame */ 597 ptr = hlen; /* Where to start from */ 598 599 /* for bridged IP traffic encapsulated inside f.e. a vlan header, 600 * we need to make room for the encapsulating header 601 */ 602 ll_rs = LL_RESERVED_SPACE_EXTRA(rt->dst.dev, nf_bridge_pad(skb)); 603 604 /* 605 * Fragment the datagram. 606 */ 607 608 offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3; 609 not_last_frag = iph->frag_off & htons(IP_MF); 610 611 /* 612 * Keep copying data until we run out. 613 */ 614 615 while (left > 0) { 616 len = left; 617 /* IF: it doesn't fit, use 'mtu' - the data space left */ 618 if (len > mtu) 619 len = mtu; 620 /* IF: we are not sending up to and including the packet end 621 then align the next start on an eight byte boundary */ 622 if (len < left) { 623 len &= ~7; 624 } 625 /* 626 * Allocate buffer. 627 */ 628 629 if ((skb2 = alloc_skb(len+hlen+ll_rs, GFP_ATOMIC)) == NULL) { 630 NETDEBUG(KERN_INFO "IP: frag: no memory for new fragment!\n"); 631 err = -ENOMEM; 632 goto fail; 633 } 634 635 /* 636 * Set up data on packet 637 */ 638 639 ip_copy_metadata(skb2, skb); 640 skb_reserve(skb2, ll_rs); 641 skb_put(skb2, len + hlen); 642 skb_reset_network_header(skb2); 643 skb2->transport_header = skb2->network_header + hlen; 644 645 /* 646 * Charge the memory for the fragment to any owner 647 * it might possess 648 */ 649 650 if (skb->sk) 651 skb_set_owner_w(skb2, skb->sk); 652 653 /* 654 * Copy the packet header into the new buffer. 655 */ 656 657 skb_copy_from_linear_data(skb, skb_network_header(skb2), hlen); 658 659 /* 660 * Copy a block of the IP datagram. 661 */ 662 if (skb_copy_bits(skb, ptr, skb_transport_header(skb2), len)) 663 BUG(); 664 left -= len; 665 666 /* 667 * Fill in the new header fields. 668 */ 669 iph = ip_hdr(skb2); 670 iph->frag_off = htons((offset >> 3)); 671 672 /* ANK: dirty, but effective trick. Upgrade options only if 673 * the segment to be fragmented was THE FIRST (otherwise, 674 * options are already fixed) and make it ONCE 675 * on the initial skb, so that all the following fragments 676 * will inherit fixed options. 677 */ 678 if (offset == 0) 679 ip_options_fragment(skb); 680 681 /* 682 * Added AC : If we are fragmenting a fragment that's not the 683 * last fragment then keep MF on each bit 684 */ 685 if (left > 0 || not_last_frag) 686 iph->frag_off |= htons(IP_MF); 687 ptr += len; 688 offset += len; 689 690 /* 691 * Put this fragment into the sending queue. 692 */ 693 iph->tot_len = htons(len + hlen); 694 695 ip_send_check(iph); 696 697 err = output(skb2); 698 if (err) 699 goto fail; 700 701 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES); 702 } 703 consume_skb(skb); 704 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS); 705 return err; 706 707fail: 708 kfree_skb(skb); 709 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); 710 return err; 711} 712EXPORT_SYMBOL(ip_fragment); 713 714int 715ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb) 716{ 717 struct iovec *iov = from; 718 719 if (skb->ip_summed == CHECKSUM_PARTIAL) { 720 if (memcpy_fromiovecend(to, iov, offset, len) < 0) 721 return -EFAULT; 722 } else { 723 __wsum csum = 0; 724 if (csum_partial_copy_fromiovecend(to, iov, offset, len, &csum) < 0) 725 return -EFAULT; 726 skb->csum = csum_block_add(skb->csum, csum, odd); 727 } 728 return 0; 729} 730EXPORT_SYMBOL(ip_generic_getfrag); 731 732static inline __wsum 733csum_page(struct page *page, int offset, int copy) 734{ 735 char *kaddr; 736 __wsum csum; 737 kaddr = kmap(page); 738 csum = csum_partial(kaddr + offset, copy, 0); 739 kunmap(page); 740 return csum; 741} 742 743static inline int ip_ufo_append_data(struct sock *sk, 744 struct sk_buff_head *queue, 745 int getfrag(void *from, char *to, int offset, int len, 746 int odd, struct sk_buff *skb), 747 void *from, int length, int hh_len, int fragheaderlen, 748 int transhdrlen, int maxfraglen, unsigned int flags) 749{ 750 struct sk_buff *skb; 751 int err; 752 753 /* There is support for UDP fragmentation offload by network 754 * device, so create one single skb packet containing complete 755 * udp datagram 756 */ 757 if ((skb = skb_peek_tail(queue)) == NULL) { 758 skb = sock_alloc_send_skb(sk, 759 hh_len + fragheaderlen + transhdrlen + 20, 760 (flags & MSG_DONTWAIT), &err); 761 762 if (skb == NULL) 763 return err; 764 765 /* reserve space for Hardware header */ 766 skb_reserve(skb, hh_len); 767 768 /* create space for UDP/IP header */ 769 skb_put(skb, fragheaderlen + transhdrlen); 770 771 /* initialize network header pointer */ 772 skb_reset_network_header(skb); 773 774 /* initialize protocol header pointer */ 775 skb->transport_header = skb->network_header + fragheaderlen; 776 777 skb->ip_summed = CHECKSUM_PARTIAL; 778 skb->csum = 0; 779 780 /* specify the length of each IP datagram fragment */ 781 skb_shinfo(skb)->gso_size = maxfraglen - fragheaderlen; 782 skb_shinfo(skb)->gso_type = SKB_GSO_UDP; 783 __skb_queue_tail(queue, skb); 784 } 785 786 return skb_append_datato_frags(sk, skb, getfrag, from, 787 (length - transhdrlen)); 788} 789 790static int __ip_append_data(struct sock *sk, 791 struct flowi4 *fl4, 792 struct sk_buff_head *queue, 793 struct inet_cork *cork, 794 int getfrag(void *from, char *to, int offset, 795 int len, int odd, struct sk_buff *skb), 796 void *from, int length, int transhdrlen, 797 unsigned int flags) 798{ 799 struct inet_sock *inet = inet_sk(sk); 800 struct sk_buff *skb; 801 802 struct ip_options *opt = cork->opt; 803 int hh_len; 804 int exthdrlen; 805 int mtu; 806 int copy; 807 int err; 808 int offset = 0; 809 unsigned int maxfraglen, fragheaderlen; 810 int csummode = CHECKSUM_NONE; 811 struct rtable *rt = (struct rtable *)cork->dst; 812 813 skb = skb_peek_tail(queue); 814 815 exthdrlen = !skb ? rt->dst.header_len : 0; 816 mtu = cork->fragsize; 817 818 hh_len = LL_RESERVED_SPACE(rt->dst.dev); 819 820 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0); 821 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen; 822 823 if (cork->length + length > 0xFFFF - fragheaderlen) { 824 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport, 825 mtu-exthdrlen); 826 return -EMSGSIZE; 827 } 828 829 /* 830 * transhdrlen > 0 means that this is the first fragment and we wish 831 * it won't be fragmented in the future. 832 */ 833 if (transhdrlen && 834 length + fragheaderlen <= mtu && 835 rt->dst.dev->features & NETIF_F_V4_CSUM && 836 !exthdrlen) 837 csummode = CHECKSUM_PARTIAL; 838 839 cork->length += length; 840 if (((length > mtu) || (skb && skb_is_gso(skb))) && 841 (sk->sk_protocol == IPPROTO_UDP) && 842 (rt->dst.dev->features & NETIF_F_UFO) && !rt->dst.header_len) { 843 err = ip_ufo_append_data(sk, queue, getfrag, from, length, 844 hh_len, fragheaderlen, transhdrlen, 845 maxfraglen, flags); 846 if (err) 847 goto error; 848 return 0; 849 } 850 851 /* So, what's going on in the loop below? 852 * 853 * We use calculated fragment length to generate chained skb, 854 * each of segments is IP fragment ready for sending to network after 855 * adding appropriate IP header. 856 */ 857 858 if (!skb) 859 goto alloc_new_skb; 860 861 while (length > 0) { 862 /* Check if the remaining data fits into current packet. */ 863 copy = mtu - skb->len; 864 if (copy < length) 865 copy = maxfraglen - skb->len; 866 if (copy <= 0) { 867 char *data; 868 unsigned int datalen; 869 unsigned int fraglen; 870 unsigned int fraggap; 871 unsigned int alloclen; 872 struct sk_buff *skb_prev; 873alloc_new_skb: 874 skb_prev = skb; 875 if (skb_prev) 876 fraggap = skb_prev->len - maxfraglen; 877 else 878 fraggap = 0; 879 880 /* 881 * If remaining data exceeds the mtu, 882 * we know we need more fragment(s). 883 */ 884 datalen = length + fraggap; 885 if (datalen > mtu - fragheaderlen) 886 datalen = maxfraglen - fragheaderlen; 887 fraglen = datalen + fragheaderlen; 888 889 if ((flags & MSG_MORE) && 890 !(rt->dst.dev->features&NETIF_F_SG)) 891 alloclen = mtu; 892 else 893 alloclen = fraglen; 894 895 alloclen += exthdrlen; 896 897 /* The last fragment gets additional space at tail. 898 * Note, with MSG_MORE we overallocate on fragments, 899 * because we have no idea what fragment will be 900 * the last. 901 */ 902 if (datalen == length + fraggap) 903 alloclen += rt->dst.trailer_len; 904 905 if (transhdrlen) { 906 skb = sock_alloc_send_skb(sk, 907 alloclen + hh_len + 15, 908 (flags & MSG_DONTWAIT), &err); 909 } else { 910 skb = NULL; 911 if (atomic_read(&sk->sk_wmem_alloc) <= 912 2 * sk->sk_sndbuf) 913 skb = sock_wmalloc(sk, 914 alloclen + hh_len + 15, 1, 915 sk->sk_allocation); 916 if (unlikely(skb == NULL)) 917 err = -ENOBUFS; 918 else 919 /* only the initial fragment is 920 time stamped */ 921 cork->tx_flags = 0; 922 } 923 if (skb == NULL) 924 goto error; 925 926 /* 927 * Fill in the control structures 928 */ 929 skb->ip_summed = csummode; 930 skb->csum = 0; 931 skb_reserve(skb, hh_len); 932 skb_shinfo(skb)->tx_flags = cork->tx_flags; 933 934 /* 935 * Find where to start putting bytes. 936 */ 937 data = skb_put(skb, fraglen + exthdrlen); 938 skb_set_network_header(skb, exthdrlen); 939 skb->transport_header = (skb->network_header + 940 fragheaderlen); 941 data += fragheaderlen + exthdrlen; 942 943 if (fraggap) { 944 skb->csum = skb_copy_and_csum_bits( 945 skb_prev, maxfraglen, 946 data + transhdrlen, fraggap, 0); 947 skb_prev->csum = csum_sub(skb_prev->csum, 948 skb->csum); 949 data += fraggap; 950 pskb_trim_unique(skb_prev, maxfraglen); 951 } 952 953 copy = datalen - transhdrlen - fraggap; 954 if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) { 955 err = -EFAULT; 956 kfree_skb(skb); 957 goto error; 958 } 959 960 offset += copy; 961 length -= datalen - fraggap; 962 transhdrlen = 0; 963 exthdrlen = 0; 964 csummode = CHECKSUM_NONE; 965 966 /* 967 * Put the packet on the pending queue. 968 */ 969 __skb_queue_tail(queue, skb); 970 continue; 971 } 972 973 if (copy > length) 974 copy = length; 975 976 if (!(rt->dst.dev->features&NETIF_F_SG)) { 977 unsigned int off; 978 979 off = skb->len; 980 if (getfrag(from, skb_put(skb, copy), 981 offset, copy, off, skb) < 0) { 982 __skb_trim(skb, off); 983 err = -EFAULT; 984 goto error; 985 } 986 } else { 987 int i = skb_shinfo(skb)->nr_frags; 988 skb_frag_t *frag = &skb_shinfo(skb)->frags[i-1]; 989 struct page *page = cork->page; 990 int off = cork->off; 991 unsigned int left; 992 993 if (page && (left = PAGE_SIZE - off) > 0) { 994 if (copy >= left) 995 copy = left; 996 if (page != skb_frag_page(frag)) { 997 if (i == MAX_SKB_FRAGS) { 998 err = -EMSGSIZE; 999 goto error; 1000 } 1001 skb_fill_page_desc(skb, i, page, off, 0); 1002 skb_frag_ref(skb, i); 1003 frag = &skb_shinfo(skb)->frags[i]; 1004 } 1005 } else if (i < MAX_SKB_FRAGS) { 1006 if (copy > PAGE_SIZE) 1007 copy = PAGE_SIZE; 1008 page = alloc_pages(sk->sk_allocation, 0); 1009 if (page == NULL) { 1010 err = -ENOMEM; 1011 goto error; 1012 } 1013 cork->page = page; 1014 cork->off = 0; 1015 1016 skb_fill_page_desc(skb, i, page, 0, 0); 1017 frag = &skb_shinfo(skb)->frags[i]; 1018 } else { 1019 err = -EMSGSIZE; 1020 goto error; 1021 } 1022 if (getfrag(from, skb_frag_address(frag)+skb_frag_size(frag), 1023 offset, copy, skb->len, skb) < 0) { 1024 err = -EFAULT; 1025 goto error; 1026 } 1027 cork->off += copy; 1028 skb_frag_size_add(frag, copy); 1029 skb->len += copy; 1030 skb->data_len += copy; 1031 skb->truesize += copy; 1032 atomic_add(copy, &sk->sk_wmem_alloc); 1033 } 1034 offset += copy; 1035 length -= copy; 1036 } 1037 1038 return 0; 1039 1040error: 1041 cork->length -= length; 1042 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS); 1043 return err; 1044} 1045 1046static int ip_setup_cork(struct sock *sk, struct inet_cork *cork, 1047 struct ipcm_cookie *ipc, struct rtable **rtp) 1048{ 1049 struct inet_sock *inet = inet_sk(sk); 1050 struct ip_options_rcu *opt; 1051 struct rtable *rt; 1052 1053 /* 1054 * setup for corking. 1055 */ 1056 opt = ipc->opt; 1057 if (opt) { 1058 if (cork->opt == NULL) { 1059 cork->opt = kmalloc(sizeof(struct ip_options) + 40, 1060 sk->sk_allocation); 1061 if (unlikely(cork->opt == NULL)) 1062 return -ENOBUFS; 1063 } 1064 memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen); 1065 cork->flags |= IPCORK_OPT; 1066 cork->addr = ipc->addr; 1067 } 1068 rt = *rtp; 1069 if (unlikely(!rt)) 1070 return -EFAULT; 1071 /* 1072 * We steal reference to this route, caller should not release it 1073 */ 1074 *rtp = NULL; 1075 cork->fragsize = inet->pmtudisc == IP_PMTUDISC_PROBE ? 1076 rt->dst.dev->mtu : dst_mtu(&rt->dst); 1077 cork->dst = &rt->dst; 1078 cork->length = 0; 1079 cork->tx_flags = ipc->tx_flags; 1080 cork->page = NULL; 1081 cork->off = 0; 1082 1083 return 0; 1084} 1085 1086/* 1087 * ip_append_data() and ip_append_page() can make one large IP datagram 1088 * from many pieces of data. Each pieces will be holded on the socket 1089 * until ip_push_pending_frames() is called. Each piece can be a page 1090 * or non-page data. 1091 * 1092 * Not only UDP, other transport protocols - e.g. raw sockets - can use 1093 * this interface potentially. 1094 * 1095 * LATER: length must be adjusted by pad at tail, when it is required. 1096 */ 1097int ip_append_data(struct sock *sk, struct flowi4 *fl4, 1098 int getfrag(void *from, char *to, int offset, int len, 1099 int odd, struct sk_buff *skb), 1100 void *from, int length, int transhdrlen, 1101 struct ipcm_cookie *ipc, struct rtable **rtp, 1102 unsigned int flags) 1103{ 1104 struct inet_sock *inet = inet_sk(sk); 1105 int err; 1106 1107 if (flags&MSG_PROBE) 1108 return 0; 1109 1110 if (skb_queue_empty(&sk->sk_write_queue)) { 1111 err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp); 1112 if (err) 1113 return err; 1114 } else { 1115 transhdrlen = 0; 1116 } 1117 1118 return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base, getfrag, 1119 from, length, transhdrlen, flags); 1120} 1121 1122ssize_t ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page, 1123 int offset, size_t size, int flags) 1124{ 1125 struct inet_sock *inet = inet_sk(sk); 1126 struct sk_buff *skb; 1127 struct rtable *rt; 1128 struct ip_options *opt = NULL; 1129 struct inet_cork *cork; 1130 int hh_len; 1131 int mtu; 1132 int len; 1133 int err; 1134 unsigned int maxfraglen, fragheaderlen, fraggap; 1135 1136 if (inet->hdrincl) 1137 return -EPERM; 1138 1139 if (flags&MSG_PROBE) 1140 return 0; 1141 1142 if (skb_queue_empty(&sk->sk_write_queue)) 1143 return -EINVAL; 1144 1145 cork = &inet->cork.base; 1146 rt = (struct rtable *)cork->dst; 1147 if (cork->flags & IPCORK_OPT) 1148 opt = cork->opt; 1149 1150 if (!(rt->dst.dev->features&NETIF_F_SG)) 1151 return -EOPNOTSUPP; 1152 1153 hh_len = LL_RESERVED_SPACE(rt->dst.dev); 1154 mtu = cork->fragsize; 1155 1156 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0); 1157 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen; 1158 1159 if (cork->length + size > 0xFFFF - fragheaderlen) { 1160 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport, mtu); 1161 return -EMSGSIZE; 1162 } 1163 1164 if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL) 1165 return -EINVAL; 1166 1167 cork->length += size; 1168 if ((size + skb->len > mtu) && 1169 (sk->sk_protocol == IPPROTO_UDP) && 1170 (rt->dst.dev->features & NETIF_F_UFO)) { 1171 skb_shinfo(skb)->gso_size = mtu - fragheaderlen; 1172 skb_shinfo(skb)->gso_type = SKB_GSO_UDP; 1173 } 1174 1175 1176 while (size > 0) { 1177 int i; 1178 1179 if (skb_is_gso(skb)) 1180 len = size; 1181 else { 1182 1183 /* Check if the remaining data fits into current packet. */ 1184 len = mtu - skb->len; 1185 if (len < size) 1186 len = maxfraglen - skb->len; 1187 } 1188 if (len <= 0) { 1189 struct sk_buff *skb_prev; 1190 int alloclen; 1191 1192 skb_prev = skb; 1193 fraggap = skb_prev->len - maxfraglen; 1194 1195 alloclen = fragheaderlen + hh_len + fraggap + 15; 1196 skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation); 1197 if (unlikely(!skb)) { 1198 err = -ENOBUFS; 1199 goto error; 1200 } 1201 1202 /* 1203 * Fill in the control structures 1204 */ 1205 skb->ip_summed = CHECKSUM_NONE; 1206 skb->csum = 0; 1207 skb_reserve(skb, hh_len); 1208 1209 /* 1210 * Find where to start putting bytes. 1211 */ 1212 skb_put(skb, fragheaderlen + fraggap); 1213 skb_reset_network_header(skb); 1214 skb->transport_header = (skb->network_header + 1215 fragheaderlen); 1216 if (fraggap) { 1217 skb->csum = skb_copy_and_csum_bits(skb_prev, 1218 maxfraglen, 1219 skb_transport_header(skb), 1220 fraggap, 0); 1221 skb_prev->csum = csum_sub(skb_prev->csum, 1222 skb->csum); 1223 pskb_trim_unique(skb_prev, maxfraglen); 1224 } 1225 1226 /* 1227 * Put the packet on the pending queue. 1228 */ 1229 __skb_queue_tail(&sk->sk_write_queue, skb); 1230 continue; 1231 } 1232 1233 i = skb_shinfo(skb)->nr_frags; 1234 if (len > size) 1235 len = size; 1236 if (skb_can_coalesce(skb, i, page, offset)) { 1237 skb_frag_size_add(&skb_shinfo(skb)->frags[i-1], len); 1238 } else if (i < MAX_SKB_FRAGS) { 1239 get_page(page); 1240 skb_fill_page_desc(skb, i, page, offset, len); 1241 } else { 1242 err = -EMSGSIZE; 1243 goto error; 1244 } 1245 1246 if (skb->ip_summed == CHECKSUM_NONE) { 1247 __wsum csum; 1248 csum = csum_page(page, offset, len); 1249 skb->csum = csum_block_add(skb->csum, csum, skb->len); 1250 } 1251 1252 skb->len += len; 1253 skb->data_len += len; 1254 skb->truesize += len; 1255 atomic_add(len, &sk->sk_wmem_alloc); 1256 offset += len; 1257 size -= len; 1258 } 1259 return 0; 1260 1261error: 1262 cork->length -= size; 1263 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS); 1264 return err; 1265} 1266 1267static void ip_cork_release(struct inet_cork *cork) 1268{ 1269 cork->flags &= ~IPCORK_OPT; 1270 kfree(cork->opt); 1271 cork->opt = NULL; 1272 dst_release(cork->dst); 1273 cork->dst = NULL; 1274} 1275 1276/* 1277 * Combined all pending IP fragments on the socket as one IP datagram 1278 * and push them out. 1279 */ 1280struct sk_buff *__ip_make_skb(struct sock *sk, 1281 struct flowi4 *fl4, 1282 struct sk_buff_head *queue, 1283 struct inet_cork *cork) 1284{ 1285 struct sk_buff *skb, *tmp_skb; 1286 struct sk_buff **tail_skb; 1287 struct inet_sock *inet = inet_sk(sk); 1288 struct net *net = sock_net(sk); 1289 struct ip_options *opt = NULL; 1290 struct rtable *rt = (struct rtable *)cork->dst; 1291 struct iphdr *iph; 1292 __be16 df = 0; 1293 __u8 ttl; 1294 1295 if ((skb = __skb_dequeue(queue)) == NULL) 1296 goto out; 1297 tail_skb = &(skb_shinfo(skb)->frag_list); 1298 1299 /* move skb->data to ip header from ext header */ 1300 if (skb->data < skb_network_header(skb)) 1301 __skb_pull(skb, skb_network_offset(skb)); 1302 while ((tmp_skb = __skb_dequeue(queue)) != NULL) { 1303 __skb_pull(tmp_skb, skb_network_header_len(skb)); 1304 *tail_skb = tmp_skb; 1305 tail_skb = &(tmp_skb->next); 1306 skb->len += tmp_skb->len; 1307 skb->data_len += tmp_skb->len; 1308 skb->truesize += tmp_skb->truesize; 1309 tmp_skb->destructor = NULL; 1310 tmp_skb->sk = NULL; 1311 } 1312 1313 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow 1314 * to fragment the frame generated here. No matter, what transforms 1315 * how transforms change size of the packet, it will come out. 1316 */ 1317 if (inet->pmtudisc < IP_PMTUDISC_DO) 1318 skb->local_df = 1; 1319 1320 /* DF bit is set when we want to see DF on outgoing frames. 1321 * If local_df is set too, we still allow to fragment this frame 1322 * locally. */ 1323 if (inet->pmtudisc >= IP_PMTUDISC_DO || 1324 (skb->len <= dst_mtu(&rt->dst) && 1325 ip_dont_fragment(sk, &rt->dst))) 1326 df = htons(IP_DF); 1327 1328 if (cork->flags & IPCORK_OPT) 1329 opt = cork->opt; 1330 1331 if (rt->rt_type == RTN_MULTICAST) 1332 ttl = inet->mc_ttl; 1333 else 1334 ttl = ip_select_ttl(inet, &rt->dst); 1335 1336 iph = (struct iphdr *)skb->data; 1337 iph->version = 4; 1338 iph->ihl = 5; 1339 iph->tos = inet->tos; 1340 iph->frag_off = df; 1341 ip_select_ident(iph, &rt->dst, sk); 1342 iph->ttl = ttl; 1343 iph->protocol = sk->sk_protocol; 1344 ip_copy_addrs(iph, fl4); 1345 1346 if (opt) { 1347 iph->ihl += opt->optlen>>2; 1348 ip_options_build(skb, opt, cork->addr, rt, 0); 1349 } 1350 1351 skb->priority = sk->sk_priority; 1352 skb->mark = sk->sk_mark; 1353 /* 1354 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec 1355 * on dst refcount 1356 */ 1357 cork->dst = NULL; 1358 skb_dst_set(skb, &rt->dst); 1359 1360 if (iph->protocol == IPPROTO_ICMP) 1361 icmp_out_count(net, ((struct icmphdr *) 1362 skb_transport_header(skb))->type); 1363 1364 ip_cork_release(cork); 1365out: 1366 return skb; 1367} 1368 1369int ip_send_skb(struct sk_buff *skb) 1370{ 1371 struct net *net = sock_net(skb->sk); 1372 int err; 1373 1374 err = ip_local_out(skb); 1375 if (err) { 1376 if (err > 0) 1377 err = net_xmit_errno(err); 1378 if (err) 1379 IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS); 1380 } 1381 1382 return err; 1383} 1384 1385int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4) 1386{ 1387 struct sk_buff *skb; 1388 1389 skb = ip_finish_skb(sk, fl4); 1390 if (!skb) 1391 return 0; 1392 1393 /* Netfilter gets whole the not fragmented skb. */ 1394 return ip_send_skb(skb); 1395} 1396 1397/* 1398 * Throw away all pending data on the socket. 1399 */ 1400static void __ip_flush_pending_frames(struct sock *sk, 1401 struct sk_buff_head *queue, 1402 struct inet_cork *cork) 1403{ 1404 struct sk_buff *skb; 1405 1406 while ((skb = __skb_dequeue_tail(queue)) != NULL) 1407 kfree_skb(skb); 1408 1409 ip_cork_release(cork); 1410} 1411 1412void ip_flush_pending_frames(struct sock *sk) 1413{ 1414 __ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork.base); 1415} 1416 1417struct sk_buff *ip_make_skb(struct sock *sk, 1418 struct flowi4 *fl4, 1419 int getfrag(void *from, char *to, int offset, 1420 int len, int odd, struct sk_buff *skb), 1421 void *from, int length, int transhdrlen, 1422 struct ipcm_cookie *ipc, struct rtable **rtp, 1423 unsigned int flags) 1424{ 1425 struct inet_cork cork; 1426 struct sk_buff_head queue; 1427 int err; 1428 1429 if (flags & MSG_PROBE) 1430 return NULL; 1431 1432 __skb_queue_head_init(&queue); 1433 1434 cork.flags = 0; 1435 cork.addr = 0; 1436 cork.opt = NULL; 1437 err = ip_setup_cork(sk, &cork, ipc, rtp); 1438 if (err) 1439 return ERR_PTR(err); 1440 1441 err = __ip_append_data(sk, fl4, &queue, &cork, getfrag, 1442 from, length, transhdrlen, flags); 1443 if (err) { 1444 __ip_flush_pending_frames(sk, &queue, &cork); 1445 return ERR_PTR(err); 1446 } 1447 1448 return __ip_make_skb(sk, fl4, &queue, &cork); 1449} 1450 1451/* 1452 * Fetch data from kernel space and fill in checksum if needed. 1453 */ 1454static int ip_reply_glue_bits(void *dptr, char *to, int offset, 1455 int len, int odd, struct sk_buff *skb) 1456{ 1457 __wsum csum; 1458 1459 csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0); 1460 skb->csum = csum_block_add(skb->csum, csum, odd); 1461 return 0; 1462} 1463 1464/* 1465 * Generic function to send a packet as reply to another packet. 1466 * Used to send some TCP resets/acks so far. 1467 * 1468 * Use a fake percpu inet socket to avoid false sharing and contention. 1469 */ 1470static DEFINE_PER_CPU(struct inet_sock, unicast_sock) = { 1471 .sk = { 1472 .__sk_common = { 1473 .skc_refcnt = ATOMIC_INIT(1), 1474 }, 1475 .sk_wmem_alloc = ATOMIC_INIT(1), 1476 .sk_allocation = GFP_ATOMIC, 1477 .sk_flags = (1UL << SOCK_USE_WRITE_QUEUE), 1478 }, 1479 .pmtudisc = IP_PMTUDISC_WANT, 1480 .uc_ttl = -1, 1481}; 1482 1483void ip_send_unicast_reply(struct net *net, struct sk_buff *skb, __be32 daddr, 1484 __be32 saddr, const struct ip_reply_arg *arg, 1485 unsigned int len) 1486{ 1487 struct ip_options_data replyopts; 1488 struct ipcm_cookie ipc; 1489 struct flowi4 fl4; 1490 struct rtable *rt = skb_rtable(skb); 1491 struct sk_buff *nskb; 1492 struct sock *sk; 1493 struct inet_sock *inet; 1494 1495 if (ip_options_echo(&replyopts.opt.opt, skb)) 1496 return; 1497 1498 ipc.addr = daddr; 1499 ipc.opt = NULL; 1500 ipc.tx_flags = 0; 1501 1502 if (replyopts.opt.opt.optlen) { 1503 ipc.opt = &replyopts.opt; 1504 1505 if (replyopts.opt.opt.srr) 1506 daddr = replyopts.opt.opt.faddr; 1507 } 1508 1509 flowi4_init_output(&fl4, arg->bound_dev_if, 0, 1510 RT_TOS(arg->tos), 1511 RT_SCOPE_UNIVERSE, ip_hdr(skb)->protocol, 1512 ip_reply_arg_flowi_flags(arg), 1513 daddr, saddr, 1514 tcp_hdr(skb)->source, tcp_hdr(skb)->dest); 1515 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4)); 1516 rt = ip_route_output_key(net, &fl4); 1517 if (IS_ERR(rt)) 1518 return; 1519 1520 inet = &get_cpu_var(unicast_sock); 1521 1522 inet->tos = arg->tos; 1523 sk = &inet->sk; 1524 sk->sk_priority = skb->priority; 1525 sk->sk_protocol = ip_hdr(skb)->protocol; 1526 sk->sk_bound_dev_if = arg->bound_dev_if; 1527 sock_net_set(sk, net); 1528 __skb_queue_head_init(&sk->sk_write_queue); 1529 sk->sk_sndbuf = sysctl_wmem_default; 1530 ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base, len, 0, 1531 &ipc, &rt, MSG_DONTWAIT); 1532 nskb = skb_peek(&sk->sk_write_queue); 1533 if (nskb) { 1534 if (arg->csumoffset >= 0) 1535 *((__sum16 *)skb_transport_header(nskb) + 1536 arg->csumoffset) = csum_fold(csum_add(nskb->csum, 1537 arg->csum)); 1538 nskb->ip_summed = CHECKSUM_NONE; 1539 skb_orphan(nskb); 1540 skb_set_queue_mapping(nskb, skb_get_queue_mapping(skb)); 1541 ip_push_pending_frames(sk, &fl4); 1542 } 1543 1544 put_cpu_var(unicast_sock); 1545 1546 ip_rt_put(rt); 1547} 1548 1549void __init ip_init(void) 1550{ 1551 ip_rt_init(); 1552 inet_initpeers(); 1553 1554#if defined(CONFIG_IP_MULTICAST) && defined(CONFIG_PROC_FS) 1555 igmp_mc_proc_init(); 1556#endif 1557} 1558