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 83 int sysctl_ip_default_ttl __read_mostly = IPDEFTTL; 84 EXPORT_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 } 92 EXPORT_SYMBOL(ip_send_check); 93 94 int __ip_local_out(struct sk_buff *skb) 95 { 96 struct iphdr *iph = ip_hdr(skb); 97 98 iph->tot_len = htons(skb->len); 99 ip_send_check(iph); 100 return nf_hook(NFPROTO_IPV4, NF_INET_LOCAL_OUT, skb, NULL, 101 skb_dst(skb)->dev, dst_output); 102 } 103 104 int ip_local_out(struct sk_buff *skb) 105 { 106 int err; 107 108 err = __ip_local_out(skb); 109 if (likely(err == 1)) 110 err = dst_output(skb); 111 112 return err; 113 } 114 EXPORT_SYMBOL_GPL(ip_local_out); 115 116 static 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 */ 129 int 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 } 164 EXPORT_SYMBOL_GPL(ip_build_and_send_pkt); 165 166 static 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 } 213 214 static 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 } 221 222 static 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 } 236 237 int 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 } 297 298 int 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 */ 318 static 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 } 325 326 int 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); 372 373 packet_routed: 374 if (inet_opt && inet_opt->opt.is_strictroute && rt->rt_uses_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; 406 407 no_route: 408 rcu_read_unlock(); 409 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES); 410 kfree_skb(skb); 411 return -EHOSTUNREACH; 412 } 413 EXPORT_SYMBOL(ip_queue_xmit); 414 415 416 static 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 */ 449 450 int 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 (IPCB(skb)->frag_max_size && 472 IPCB(skb)->frag_max_size > dst_mtu(&rt->dst)))) { 473 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); 474 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, 475 htonl(ip_skb_dst_mtu(skb))); 476 kfree_skb(skb); 477 return -EMSGSIZE; 478 } 479 480 /* 481 * Setup starting values. 482 */ 483 484 hlen = iph->ihl * 4; 485 mtu = dst_mtu(&rt->dst) - hlen; /* Size of data space */ 486 #ifdef CONFIG_BRIDGE_NETFILTER 487 if (skb->nf_bridge) 488 mtu -= nf_bridge_mtu_reduction(skb); 489 #endif 490 IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE; 491 492 /* When frag_list is given, use it. First, check its validity: 493 * some transformers could create wrong frag_list or break existing 494 * one, it is not prohibited. In this case fall back to copying. 495 * 496 * LATER: this step can be merged to real generation of fragments, 497 * we can switch to copy when see the first bad fragment. 498 */ 499 if (skb_has_frag_list(skb)) { 500 struct sk_buff *frag, *frag2; 501 int first_len = skb_pagelen(skb); 502 503 if (first_len - hlen > mtu || 504 ((first_len - hlen) & 7) || 505 ip_is_fragment(iph) || 506 skb_cloned(skb)) 507 goto slow_path; 508 509 skb_walk_frags(skb, frag) { 510 /* Correct geometry. */ 511 if (frag->len > mtu || 512 ((frag->len & 7) && frag->next) || 513 skb_headroom(frag) < hlen) 514 goto slow_path_clean; 515 516 /* Partially cloned skb? */ 517 if (skb_shared(frag)) 518 goto slow_path_clean; 519 520 BUG_ON(frag->sk); 521 if (skb->sk) { 522 frag->sk = skb->sk; 523 frag->destructor = sock_wfree; 524 } 525 skb->truesize -= frag->truesize; 526 } 527 528 /* Everything is OK. Generate! */ 529 530 err = 0; 531 offset = 0; 532 frag = skb_shinfo(skb)->frag_list; 533 skb_frag_list_init(skb); 534 skb->data_len = first_len - skb_headlen(skb); 535 skb->len = first_len; 536 iph->tot_len = htons(first_len); 537 iph->frag_off = htons(IP_MF); 538 ip_send_check(iph); 539 540 for (;;) { 541 /* Prepare header of the next frame, 542 * before previous one went down. */ 543 if (frag) { 544 frag->ip_summed = CHECKSUM_NONE; 545 skb_reset_transport_header(frag); 546 __skb_push(frag, hlen); 547 skb_reset_network_header(frag); 548 memcpy(skb_network_header(frag), iph, hlen); 549 iph = ip_hdr(frag); 550 iph->tot_len = htons(frag->len); 551 ip_copy_metadata(frag, skb); 552 if (offset == 0) 553 ip_options_fragment(frag); 554 offset += skb->len - hlen; 555 iph->frag_off = htons(offset>>3); 556 if (frag->next != NULL) 557 iph->frag_off |= htons(IP_MF); 558 /* Ready, complete checksum */ 559 ip_send_check(iph); 560 } 561 562 err = output(skb); 563 564 if (!err) 565 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES); 566 if (err || !frag) 567 break; 568 569 skb = frag; 570 frag = skb->next; 571 skb->next = NULL; 572 } 573 574 if (err == 0) { 575 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS); 576 return 0; 577 } 578 579 while (frag) { 580 skb = frag->next; 581 kfree_skb(frag); 582 frag = skb; 583 } 584 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); 585 return err; 586 587 slow_path_clean: 588 skb_walk_frags(skb, frag2) { 589 if (frag2 == frag) 590 break; 591 frag2->sk = NULL; 592 frag2->destructor = NULL; 593 skb->truesize += frag2->truesize; 594 } 595 } 596 597 slow_path: 598 left = skb->len - hlen; /* Space per frame */ 599 ptr = hlen; /* Where to start from */ 600 601 /* for bridged IP traffic encapsulated inside f.e. a vlan header, 602 * we need to make room for the encapsulating header 603 */ 604 ll_rs = LL_RESERVED_SPACE_EXTRA(rt->dst.dev, nf_bridge_pad(skb)); 605 606 /* 607 * Fragment the datagram. 608 */ 609 610 offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3; 611 not_last_frag = iph->frag_off & htons(IP_MF); 612 613 /* 614 * Keep copying data until we run out. 615 */ 616 617 while (left > 0) { 618 len = left; 619 /* IF: it doesn't fit, use 'mtu' - the data space left */ 620 if (len > mtu) 621 len = mtu; 622 /* IF: we are not sending up to and including the packet end 623 then align the next start on an eight byte boundary */ 624 if (len < left) { 625 len &= ~7; 626 } 627 /* 628 * Allocate buffer. 629 */ 630 631 if ((skb2 = alloc_skb(len+hlen+ll_rs, GFP_ATOMIC)) == NULL) { 632 NETDEBUG(KERN_INFO "IP: frag: no memory for new fragment!\n"); 633 err = -ENOMEM; 634 goto fail; 635 } 636 637 /* 638 * Set up data on packet 639 */ 640 641 ip_copy_metadata(skb2, skb); 642 skb_reserve(skb2, ll_rs); 643 skb_put(skb2, len + hlen); 644 skb_reset_network_header(skb2); 645 skb2->transport_header = skb2->network_header + hlen; 646 647 /* 648 * Charge the memory for the fragment to any owner 649 * it might possess 650 */ 651 652 if (skb->sk) 653 skb_set_owner_w(skb2, skb->sk); 654 655 /* 656 * Copy the packet header into the new buffer. 657 */ 658 659 skb_copy_from_linear_data(skb, skb_network_header(skb2), hlen); 660 661 /* 662 * Copy a block of the IP datagram. 663 */ 664 if (skb_copy_bits(skb, ptr, skb_transport_header(skb2), len)) 665 BUG(); 666 left -= len; 667 668 /* 669 * Fill in the new header fields. 670 */ 671 iph = ip_hdr(skb2); 672 iph->frag_off = htons((offset >> 3)); 673 674 /* ANK: dirty, but effective trick. Upgrade options only if 675 * the segment to be fragmented was THE FIRST (otherwise, 676 * options are already fixed) and make it ONCE 677 * on the initial skb, so that all the following fragments 678 * will inherit fixed options. 679 */ 680 if (offset == 0) 681 ip_options_fragment(skb); 682 683 /* 684 * Added AC : If we are fragmenting a fragment that's not the 685 * last fragment then keep MF on each bit 686 */ 687 if (left > 0 || not_last_frag) 688 iph->frag_off |= htons(IP_MF); 689 ptr += len; 690 offset += len; 691 692 /* 693 * Put this fragment into the sending queue. 694 */ 695 iph->tot_len = htons(len + hlen); 696 697 ip_send_check(iph); 698 699 err = output(skb2); 700 if (err) 701 goto fail; 702 703 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES); 704 } 705 consume_skb(skb); 706 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS); 707 return err; 708 709 fail: 710 kfree_skb(skb); 711 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); 712 return err; 713 } 714 EXPORT_SYMBOL(ip_fragment); 715 716 int 717 ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb) 718 { 719 struct iovec *iov = from; 720 721 if (skb->ip_summed == CHECKSUM_PARTIAL) { 722 if (memcpy_fromiovecend(to, iov, offset, len) < 0) 723 return -EFAULT; 724 } else { 725 __wsum csum = 0; 726 if (csum_partial_copy_fromiovecend(to, iov, offset, len, &csum) < 0) 727 return -EFAULT; 728 skb->csum = csum_block_add(skb->csum, csum, odd); 729 } 730 return 0; 731 } 732 EXPORT_SYMBOL(ip_generic_getfrag); 733 734 static inline __wsum 735 csum_page(struct page *page, int offset, int copy) 736 { 737 char *kaddr; 738 __wsum csum; 739 kaddr = kmap(page); 740 csum = csum_partial(kaddr + offset, copy, 0); 741 kunmap(page); 742 return csum; 743 } 744 745 static inline int ip_ufo_append_data(struct sock *sk, 746 struct sk_buff_head *queue, 747 int getfrag(void *from, char *to, int offset, int len, 748 int odd, struct sk_buff *skb), 749 void *from, int length, int hh_len, int fragheaderlen, 750 int transhdrlen, int maxfraglen, unsigned int flags) 751 { 752 struct sk_buff *skb; 753 int err; 754 755 /* There is support for UDP fragmentation offload by network 756 * device, so create one single skb packet containing complete 757 * udp datagram 758 */ 759 if ((skb = skb_peek_tail(queue)) == NULL) { 760 skb = sock_alloc_send_skb(sk, 761 hh_len + fragheaderlen + transhdrlen + 20, 762 (flags & MSG_DONTWAIT), &err); 763 764 if (skb == NULL) 765 return err; 766 767 /* reserve space for Hardware header */ 768 skb_reserve(skb, hh_len); 769 770 /* create space for UDP/IP header */ 771 skb_put(skb, fragheaderlen + transhdrlen); 772 773 /* initialize network header pointer */ 774 skb_reset_network_header(skb); 775 776 /* initialize protocol header pointer */ 777 skb->transport_header = skb->network_header + fragheaderlen; 778 779 skb->ip_summed = CHECKSUM_PARTIAL; 780 skb->csum = 0; 781 782 /* specify the length of each IP datagram fragment */ 783 skb_shinfo(skb)->gso_size = maxfraglen - fragheaderlen; 784 skb_shinfo(skb)->gso_type = SKB_GSO_UDP; 785 __skb_queue_tail(queue, skb); 786 } 787 788 return skb_append_datato_frags(sk, skb, getfrag, from, 789 (length - transhdrlen)); 790 } 791 792 static int __ip_append_data(struct sock *sk, 793 struct flowi4 *fl4, 794 struct sk_buff_head *queue, 795 struct inet_cork *cork, 796 struct page_frag *pfrag, 797 int getfrag(void *from, char *to, int offset, 798 int len, int odd, struct sk_buff *skb), 799 void *from, int length, int transhdrlen, 800 unsigned int flags) 801 { 802 struct inet_sock *inet = inet_sk(sk); 803 struct sk_buff *skb; 804 805 struct ip_options *opt = cork->opt; 806 int hh_len; 807 int exthdrlen; 808 int mtu; 809 int copy; 810 int err; 811 int offset = 0; 812 unsigned int maxfraglen, fragheaderlen; 813 int csummode = CHECKSUM_NONE; 814 struct rtable *rt = (struct rtable *)cork->dst; 815 816 skb = skb_peek_tail(queue); 817 818 exthdrlen = !skb ? rt->dst.header_len : 0; 819 mtu = cork->fragsize; 820 821 hh_len = LL_RESERVED_SPACE(rt->dst.dev); 822 823 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0); 824 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen; 825 826 if (cork->length + length > 0xFFFF - fragheaderlen) { 827 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport, 828 mtu-exthdrlen); 829 return -EMSGSIZE; 830 } 831 832 /* 833 * transhdrlen > 0 means that this is the first fragment and we wish 834 * it won't be fragmented in the future. 835 */ 836 if (transhdrlen && 837 length + fragheaderlen <= mtu && 838 rt->dst.dev->features & NETIF_F_V4_CSUM && 839 !exthdrlen) 840 csummode = CHECKSUM_PARTIAL; 841 842 cork->length += length; 843 if (((length > mtu) || (skb && skb_is_gso(skb))) && 844 (sk->sk_protocol == IPPROTO_UDP) && 845 (rt->dst.dev->features & NETIF_F_UFO) && !rt->dst.header_len) { 846 err = ip_ufo_append_data(sk, queue, getfrag, from, length, 847 hh_len, fragheaderlen, transhdrlen, 848 maxfraglen, flags); 849 if (err) 850 goto error; 851 return 0; 852 } 853 854 /* So, what's going on in the loop below? 855 * 856 * We use calculated fragment length to generate chained skb, 857 * each of segments is IP fragment ready for sending to network after 858 * adding appropriate IP header. 859 */ 860 861 if (!skb) 862 goto alloc_new_skb; 863 864 while (length > 0) { 865 /* Check if the remaining data fits into current packet. */ 866 copy = mtu - skb->len; 867 if (copy < length) 868 copy = maxfraglen - skb->len; 869 if (copy <= 0) { 870 char *data; 871 unsigned int datalen; 872 unsigned int fraglen; 873 unsigned int fraggap; 874 unsigned int alloclen; 875 struct sk_buff *skb_prev; 876 alloc_new_skb: 877 skb_prev = skb; 878 if (skb_prev) 879 fraggap = skb_prev->len - maxfraglen; 880 else 881 fraggap = 0; 882 883 /* 884 * If remaining data exceeds the mtu, 885 * we know we need more fragment(s). 886 */ 887 datalen = length + fraggap; 888 if (datalen > mtu - fragheaderlen) 889 datalen = maxfraglen - fragheaderlen; 890 fraglen = datalen + fragheaderlen; 891 892 if ((flags & MSG_MORE) && 893 !(rt->dst.dev->features&NETIF_F_SG)) 894 alloclen = mtu; 895 else 896 alloclen = fraglen; 897 898 alloclen += exthdrlen; 899 900 /* The last fragment gets additional space at tail. 901 * Note, with MSG_MORE we overallocate on fragments, 902 * because we have no idea what fragment will be 903 * the last. 904 */ 905 if (datalen == length + fraggap) 906 alloclen += rt->dst.trailer_len; 907 908 if (transhdrlen) { 909 skb = sock_alloc_send_skb(sk, 910 alloclen + hh_len + 15, 911 (flags & MSG_DONTWAIT), &err); 912 } else { 913 skb = NULL; 914 if (atomic_read(&sk->sk_wmem_alloc) <= 915 2 * sk->sk_sndbuf) 916 skb = sock_wmalloc(sk, 917 alloclen + hh_len + 15, 1, 918 sk->sk_allocation); 919 if (unlikely(skb == NULL)) 920 err = -ENOBUFS; 921 else 922 /* only the initial fragment is 923 time stamped */ 924 cork->tx_flags = 0; 925 } 926 if (skb == NULL) 927 goto error; 928 929 /* 930 * Fill in the control structures 931 */ 932 skb->ip_summed = csummode; 933 skb->csum = 0; 934 skb_reserve(skb, hh_len); 935 skb_shinfo(skb)->tx_flags = cork->tx_flags; 936 937 /* 938 * Find where to start putting bytes. 939 */ 940 data = skb_put(skb, fraglen + exthdrlen); 941 skb_set_network_header(skb, exthdrlen); 942 skb->transport_header = (skb->network_header + 943 fragheaderlen); 944 data += fragheaderlen + exthdrlen; 945 946 if (fraggap) { 947 skb->csum = skb_copy_and_csum_bits( 948 skb_prev, maxfraglen, 949 data + transhdrlen, fraggap, 0); 950 skb_prev->csum = csum_sub(skb_prev->csum, 951 skb->csum); 952 data += fraggap; 953 pskb_trim_unique(skb_prev, maxfraglen); 954 } 955 956 copy = datalen - transhdrlen - fraggap; 957 if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) { 958 err = -EFAULT; 959 kfree_skb(skb); 960 goto error; 961 } 962 963 offset += copy; 964 length -= datalen - fraggap; 965 transhdrlen = 0; 966 exthdrlen = 0; 967 csummode = CHECKSUM_NONE; 968 969 /* 970 * Put the packet on the pending queue. 971 */ 972 __skb_queue_tail(queue, skb); 973 continue; 974 } 975 976 if (copy > length) 977 copy = length; 978 979 if (!(rt->dst.dev->features&NETIF_F_SG)) { 980 unsigned int off; 981 982 off = skb->len; 983 if (getfrag(from, skb_put(skb, copy), 984 offset, copy, off, skb) < 0) { 985 __skb_trim(skb, off); 986 err = -EFAULT; 987 goto error; 988 } 989 } else { 990 int i = skb_shinfo(skb)->nr_frags; 991 992 err = -ENOMEM; 993 if (!sk_page_frag_refill(sk, pfrag)) 994 goto error; 995 996 if (!skb_can_coalesce(skb, i, pfrag->page, 997 pfrag->offset)) { 998 err = -EMSGSIZE; 999 if (i == MAX_SKB_FRAGS) 1000 goto error; 1001 1002 __skb_fill_page_desc(skb, i, pfrag->page, 1003 pfrag->offset, 0); 1004 skb_shinfo(skb)->nr_frags = ++i; 1005 get_page(pfrag->page); 1006 } 1007 copy = min_t(int, copy, pfrag->size - pfrag->offset); 1008 if (getfrag(from, 1009 page_address(pfrag->page) + pfrag->offset, 1010 offset, copy, skb->len, skb) < 0) 1011 goto error_efault; 1012 1013 pfrag->offset += copy; 1014 skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy); 1015 skb->len += copy; 1016 skb->data_len += copy; 1017 skb->truesize += copy; 1018 atomic_add(copy, &sk->sk_wmem_alloc); 1019 } 1020 offset += copy; 1021 length -= copy; 1022 } 1023 1024 return 0; 1025 1026 error_efault: 1027 err = -EFAULT; 1028 error: 1029 cork->length -= length; 1030 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS); 1031 return err; 1032 } 1033 1034 static int ip_setup_cork(struct sock *sk, struct inet_cork *cork, 1035 struct ipcm_cookie *ipc, struct rtable **rtp) 1036 { 1037 struct inet_sock *inet = inet_sk(sk); 1038 struct ip_options_rcu *opt; 1039 struct rtable *rt; 1040 1041 /* 1042 * setup for corking. 1043 */ 1044 opt = ipc->opt; 1045 if (opt) { 1046 if (cork->opt == NULL) { 1047 cork->opt = kmalloc(sizeof(struct ip_options) + 40, 1048 sk->sk_allocation); 1049 if (unlikely(cork->opt == NULL)) 1050 return -ENOBUFS; 1051 } 1052 memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen); 1053 cork->flags |= IPCORK_OPT; 1054 cork->addr = ipc->addr; 1055 } 1056 rt = *rtp; 1057 if (unlikely(!rt)) 1058 return -EFAULT; 1059 /* 1060 * We steal reference to this route, caller should not release it 1061 */ 1062 *rtp = NULL; 1063 cork->fragsize = inet->pmtudisc == IP_PMTUDISC_PROBE ? 1064 rt->dst.dev->mtu : dst_mtu(&rt->dst); 1065 cork->dst = &rt->dst; 1066 cork->length = 0; 1067 cork->tx_flags = ipc->tx_flags; 1068 1069 return 0; 1070 } 1071 1072 /* 1073 * ip_append_data() and ip_append_page() can make one large IP datagram 1074 * from many pieces of data. Each pieces will be holded on the socket 1075 * until ip_push_pending_frames() is called. Each piece can be a page 1076 * or non-page data. 1077 * 1078 * Not only UDP, other transport protocols - e.g. raw sockets - can use 1079 * this interface potentially. 1080 * 1081 * LATER: length must be adjusted by pad at tail, when it is required. 1082 */ 1083 int ip_append_data(struct sock *sk, struct flowi4 *fl4, 1084 int getfrag(void *from, char *to, int offset, int len, 1085 int odd, struct sk_buff *skb), 1086 void *from, int length, int transhdrlen, 1087 struct ipcm_cookie *ipc, struct rtable **rtp, 1088 unsigned int flags) 1089 { 1090 struct inet_sock *inet = inet_sk(sk); 1091 int err; 1092 1093 if (flags&MSG_PROBE) 1094 return 0; 1095 1096 if (skb_queue_empty(&sk->sk_write_queue)) { 1097 err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp); 1098 if (err) 1099 return err; 1100 } else { 1101 transhdrlen = 0; 1102 } 1103 1104 return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base, 1105 sk_page_frag(sk), getfrag, 1106 from, length, transhdrlen, flags); 1107 } 1108 1109 ssize_t ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page, 1110 int offset, size_t size, int flags) 1111 { 1112 struct inet_sock *inet = inet_sk(sk); 1113 struct sk_buff *skb; 1114 struct rtable *rt; 1115 struct ip_options *opt = NULL; 1116 struct inet_cork *cork; 1117 int hh_len; 1118 int mtu; 1119 int len; 1120 int err; 1121 unsigned int maxfraglen, fragheaderlen, fraggap; 1122 1123 if (inet->hdrincl) 1124 return -EPERM; 1125 1126 if (flags&MSG_PROBE) 1127 return 0; 1128 1129 if (skb_queue_empty(&sk->sk_write_queue)) 1130 return -EINVAL; 1131 1132 cork = &inet->cork.base; 1133 rt = (struct rtable *)cork->dst; 1134 if (cork->flags & IPCORK_OPT) 1135 opt = cork->opt; 1136 1137 if (!(rt->dst.dev->features&NETIF_F_SG)) 1138 return -EOPNOTSUPP; 1139 1140 hh_len = LL_RESERVED_SPACE(rt->dst.dev); 1141 mtu = cork->fragsize; 1142 1143 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0); 1144 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen; 1145 1146 if (cork->length + size > 0xFFFF - fragheaderlen) { 1147 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport, mtu); 1148 return -EMSGSIZE; 1149 } 1150 1151 if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL) 1152 return -EINVAL; 1153 1154 cork->length += size; 1155 if ((size + skb->len > mtu) && 1156 (sk->sk_protocol == IPPROTO_UDP) && 1157 (rt->dst.dev->features & NETIF_F_UFO)) { 1158 skb_shinfo(skb)->gso_size = mtu - fragheaderlen; 1159 skb_shinfo(skb)->gso_type = SKB_GSO_UDP; 1160 } 1161 1162 1163 while (size > 0) { 1164 int i; 1165 1166 if (skb_is_gso(skb)) 1167 len = size; 1168 else { 1169 1170 /* Check if the remaining data fits into current packet. */ 1171 len = mtu - skb->len; 1172 if (len < size) 1173 len = maxfraglen - skb->len; 1174 } 1175 if (len <= 0) { 1176 struct sk_buff *skb_prev; 1177 int alloclen; 1178 1179 skb_prev = skb; 1180 fraggap = skb_prev->len - maxfraglen; 1181 1182 alloclen = fragheaderlen + hh_len + fraggap + 15; 1183 skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation); 1184 if (unlikely(!skb)) { 1185 err = -ENOBUFS; 1186 goto error; 1187 } 1188 1189 /* 1190 * Fill in the control structures 1191 */ 1192 skb->ip_summed = CHECKSUM_NONE; 1193 skb->csum = 0; 1194 skb_reserve(skb, hh_len); 1195 1196 /* 1197 * Find where to start putting bytes. 1198 */ 1199 skb_put(skb, fragheaderlen + fraggap); 1200 skb_reset_network_header(skb); 1201 skb->transport_header = (skb->network_header + 1202 fragheaderlen); 1203 if (fraggap) { 1204 skb->csum = skb_copy_and_csum_bits(skb_prev, 1205 maxfraglen, 1206 skb_transport_header(skb), 1207 fraggap, 0); 1208 skb_prev->csum = csum_sub(skb_prev->csum, 1209 skb->csum); 1210 pskb_trim_unique(skb_prev, maxfraglen); 1211 } 1212 1213 /* 1214 * Put the packet on the pending queue. 1215 */ 1216 __skb_queue_tail(&sk->sk_write_queue, skb); 1217 continue; 1218 } 1219 1220 i = skb_shinfo(skb)->nr_frags; 1221 if (len > size) 1222 len = size; 1223 if (skb_can_coalesce(skb, i, page, offset)) { 1224 skb_frag_size_add(&skb_shinfo(skb)->frags[i-1], len); 1225 } else if (i < MAX_SKB_FRAGS) { 1226 get_page(page); 1227 skb_fill_page_desc(skb, i, page, offset, len); 1228 } else { 1229 err = -EMSGSIZE; 1230 goto error; 1231 } 1232 1233 if (skb->ip_summed == CHECKSUM_NONE) { 1234 __wsum csum; 1235 csum = csum_page(page, offset, len); 1236 skb->csum = csum_block_add(skb->csum, csum, skb->len); 1237 } 1238 1239 skb->len += len; 1240 skb->data_len += len; 1241 skb->truesize += len; 1242 atomic_add(len, &sk->sk_wmem_alloc); 1243 offset += len; 1244 size -= len; 1245 } 1246 return 0; 1247 1248 error: 1249 cork->length -= size; 1250 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS); 1251 return err; 1252 } 1253 1254 static void ip_cork_release(struct inet_cork *cork) 1255 { 1256 cork->flags &= ~IPCORK_OPT; 1257 kfree(cork->opt); 1258 cork->opt = NULL; 1259 dst_release(cork->dst); 1260 cork->dst = NULL; 1261 } 1262 1263 /* 1264 * Combined all pending IP fragments on the socket as one IP datagram 1265 * and push them out. 1266 */ 1267 struct sk_buff *__ip_make_skb(struct sock *sk, 1268 struct flowi4 *fl4, 1269 struct sk_buff_head *queue, 1270 struct inet_cork *cork) 1271 { 1272 struct sk_buff *skb, *tmp_skb; 1273 struct sk_buff **tail_skb; 1274 struct inet_sock *inet = inet_sk(sk); 1275 struct net *net = sock_net(sk); 1276 struct ip_options *opt = NULL; 1277 struct rtable *rt = (struct rtable *)cork->dst; 1278 struct iphdr *iph; 1279 __be16 df = 0; 1280 __u8 ttl; 1281 1282 if ((skb = __skb_dequeue(queue)) == NULL) 1283 goto out; 1284 tail_skb = &(skb_shinfo(skb)->frag_list); 1285 1286 /* move skb->data to ip header from ext header */ 1287 if (skb->data < skb_network_header(skb)) 1288 __skb_pull(skb, skb_network_offset(skb)); 1289 while ((tmp_skb = __skb_dequeue(queue)) != NULL) { 1290 __skb_pull(tmp_skb, skb_network_header_len(skb)); 1291 *tail_skb = tmp_skb; 1292 tail_skb = &(tmp_skb->next); 1293 skb->len += tmp_skb->len; 1294 skb->data_len += tmp_skb->len; 1295 skb->truesize += tmp_skb->truesize; 1296 tmp_skb->destructor = NULL; 1297 tmp_skb->sk = NULL; 1298 } 1299 1300 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow 1301 * to fragment the frame generated here. No matter, what transforms 1302 * how transforms change size of the packet, it will come out. 1303 */ 1304 if (inet->pmtudisc < IP_PMTUDISC_DO) 1305 skb->local_df = 1; 1306 1307 /* DF bit is set when we want to see DF on outgoing frames. 1308 * If local_df is set too, we still allow to fragment this frame 1309 * locally. */ 1310 if (inet->pmtudisc >= IP_PMTUDISC_DO || 1311 (skb->len <= dst_mtu(&rt->dst) && 1312 ip_dont_fragment(sk, &rt->dst))) 1313 df = htons(IP_DF); 1314 1315 if (cork->flags & IPCORK_OPT) 1316 opt = cork->opt; 1317 1318 if (rt->rt_type == RTN_MULTICAST) 1319 ttl = inet->mc_ttl; 1320 else 1321 ttl = ip_select_ttl(inet, &rt->dst); 1322 1323 iph = (struct iphdr *)skb->data; 1324 iph->version = 4; 1325 iph->ihl = 5; 1326 iph->tos = inet->tos; 1327 iph->frag_off = df; 1328 iph->ttl = ttl; 1329 iph->protocol = sk->sk_protocol; 1330 ip_copy_addrs(iph, fl4); 1331 ip_select_ident(iph, &rt->dst, sk); 1332 1333 if (opt) { 1334 iph->ihl += opt->optlen>>2; 1335 ip_options_build(skb, opt, cork->addr, rt, 0); 1336 } 1337 1338 skb->priority = sk->sk_priority; 1339 skb->mark = sk->sk_mark; 1340 /* 1341 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec 1342 * on dst refcount 1343 */ 1344 cork->dst = NULL; 1345 skb_dst_set(skb, &rt->dst); 1346 1347 if (iph->protocol == IPPROTO_ICMP) 1348 icmp_out_count(net, ((struct icmphdr *) 1349 skb_transport_header(skb))->type); 1350 1351 ip_cork_release(cork); 1352 out: 1353 return skb; 1354 } 1355 1356 int ip_send_skb(struct net *net, struct sk_buff *skb) 1357 { 1358 int err; 1359 1360 err = ip_local_out(skb); 1361 if (err) { 1362 if (err > 0) 1363 err = net_xmit_errno(err); 1364 if (err) 1365 IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS); 1366 } 1367 1368 return err; 1369 } 1370 1371 int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4) 1372 { 1373 struct sk_buff *skb; 1374 1375 skb = ip_finish_skb(sk, fl4); 1376 if (!skb) 1377 return 0; 1378 1379 /* Netfilter gets whole the not fragmented skb. */ 1380 return ip_send_skb(sock_net(sk), skb); 1381 } 1382 1383 /* 1384 * Throw away all pending data on the socket. 1385 */ 1386 static void __ip_flush_pending_frames(struct sock *sk, 1387 struct sk_buff_head *queue, 1388 struct inet_cork *cork) 1389 { 1390 struct sk_buff *skb; 1391 1392 while ((skb = __skb_dequeue_tail(queue)) != NULL) 1393 kfree_skb(skb); 1394 1395 ip_cork_release(cork); 1396 } 1397 1398 void ip_flush_pending_frames(struct sock *sk) 1399 { 1400 __ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork.base); 1401 } 1402 1403 struct sk_buff *ip_make_skb(struct sock *sk, 1404 struct flowi4 *fl4, 1405 int getfrag(void *from, char *to, int offset, 1406 int len, int odd, struct sk_buff *skb), 1407 void *from, int length, int transhdrlen, 1408 struct ipcm_cookie *ipc, struct rtable **rtp, 1409 unsigned int flags) 1410 { 1411 struct inet_cork cork; 1412 struct sk_buff_head queue; 1413 int err; 1414 1415 if (flags & MSG_PROBE) 1416 return NULL; 1417 1418 __skb_queue_head_init(&queue); 1419 1420 cork.flags = 0; 1421 cork.addr = 0; 1422 cork.opt = NULL; 1423 err = ip_setup_cork(sk, &cork, ipc, rtp); 1424 if (err) 1425 return ERR_PTR(err); 1426 1427 err = __ip_append_data(sk, fl4, &queue, &cork, 1428 ¤t->task_frag, getfrag, 1429 from, length, transhdrlen, flags); 1430 if (err) { 1431 __ip_flush_pending_frames(sk, &queue, &cork); 1432 return ERR_PTR(err); 1433 } 1434 1435 return __ip_make_skb(sk, fl4, &queue, &cork); 1436 } 1437 1438 /* 1439 * Fetch data from kernel space and fill in checksum if needed. 1440 */ 1441 static int ip_reply_glue_bits(void *dptr, char *to, int offset, 1442 int len, int odd, struct sk_buff *skb) 1443 { 1444 __wsum csum; 1445 1446 csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0); 1447 skb->csum = csum_block_add(skb->csum, csum, odd); 1448 return 0; 1449 } 1450 1451 /* 1452 * Generic function to send a packet as reply to another packet. 1453 * Used to send some TCP resets/acks so far. 1454 * 1455 * Use a fake percpu inet socket to avoid false sharing and contention. 1456 */ 1457 static DEFINE_PER_CPU(struct inet_sock, unicast_sock) = { 1458 .sk = { 1459 .__sk_common = { 1460 .skc_refcnt = ATOMIC_INIT(1), 1461 }, 1462 .sk_wmem_alloc = ATOMIC_INIT(1), 1463 .sk_allocation = GFP_ATOMIC, 1464 .sk_flags = (1UL << SOCK_USE_WRITE_QUEUE), 1465 }, 1466 .pmtudisc = IP_PMTUDISC_WANT, 1467 .uc_ttl = -1, 1468 }; 1469 1470 void ip_send_unicast_reply(struct net *net, struct sk_buff *skb, __be32 daddr, 1471 __be32 saddr, const struct ip_reply_arg *arg, 1472 unsigned int len) 1473 { 1474 struct ip_options_data replyopts; 1475 struct ipcm_cookie ipc; 1476 struct flowi4 fl4; 1477 struct rtable *rt = skb_rtable(skb); 1478 struct sk_buff *nskb; 1479 struct sock *sk; 1480 struct inet_sock *inet; 1481 1482 if (ip_options_echo(&replyopts.opt.opt, skb)) 1483 return; 1484 1485 ipc.addr = daddr; 1486 ipc.opt = NULL; 1487 ipc.tx_flags = 0; 1488 1489 if (replyopts.opt.opt.optlen) { 1490 ipc.opt = &replyopts.opt; 1491 1492 if (replyopts.opt.opt.srr) 1493 daddr = replyopts.opt.opt.faddr; 1494 } 1495 1496 flowi4_init_output(&fl4, arg->bound_dev_if, 0, 1497 RT_TOS(arg->tos), 1498 RT_SCOPE_UNIVERSE, ip_hdr(skb)->protocol, 1499 ip_reply_arg_flowi_flags(arg), 1500 daddr, saddr, 1501 tcp_hdr(skb)->source, tcp_hdr(skb)->dest); 1502 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4)); 1503 rt = ip_route_output_key(net, &fl4); 1504 if (IS_ERR(rt)) 1505 return; 1506 1507 inet = &get_cpu_var(unicast_sock); 1508 1509 inet->tos = arg->tos; 1510 sk = &inet->sk; 1511 sk->sk_priority = skb->priority; 1512 sk->sk_protocol = ip_hdr(skb)->protocol; 1513 sk->sk_bound_dev_if = arg->bound_dev_if; 1514 sock_net_set(sk, net); 1515 __skb_queue_head_init(&sk->sk_write_queue); 1516 sk->sk_sndbuf = sysctl_wmem_default; 1517 ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base, len, 0, 1518 &ipc, &rt, MSG_DONTWAIT); 1519 nskb = skb_peek(&sk->sk_write_queue); 1520 if (nskb) { 1521 if (arg->csumoffset >= 0) 1522 *((__sum16 *)skb_transport_header(nskb) + 1523 arg->csumoffset) = csum_fold(csum_add(nskb->csum, 1524 arg->csum)); 1525 nskb->ip_summed = CHECKSUM_NONE; 1526 skb_orphan(nskb); 1527 skb_set_queue_mapping(nskb, skb_get_queue_mapping(skb)); 1528 ip_push_pending_frames(sk, &fl4); 1529 } 1530 1531 put_cpu_var(unicast_sock); 1532 1533 ip_rt_put(rt); 1534 } 1535 1536 void __init ip_init(void) 1537 { 1538 ip_rt_init(); 1539 inet_initpeers(); 1540 1541 #if defined(CONFIG_IP_MULTICAST) && defined(CONFIG_PROC_FS) 1542 igmp_mc_proc_init(); 1543 #endif 1544 } 1545