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