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 static int ip_fragment(struct sock *sk, struct sk_buff *skb, 87 unsigned int mtu, 88 int (*output)(struct sock *, struct sk_buff *)); 89 90 /* Generate a checksum for an outgoing IP datagram. */ 91 void ip_send_check(struct iphdr *iph) 92 { 93 iph->check = 0; 94 iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl); 95 } 96 EXPORT_SYMBOL(ip_send_check); 97 98 static int __ip_local_out_sk(struct sock *sk, struct sk_buff *skb) 99 { 100 struct net *net = dev_net(skb_dst(skb)->dev); 101 struct iphdr *iph = ip_hdr(skb); 102 103 iph->tot_len = htons(skb->len); 104 ip_send_check(iph); 105 return nf_hook(NFPROTO_IPV4, NF_INET_LOCAL_OUT, 106 net, sk, skb, NULL, skb_dst(skb)->dev, 107 dst_output_okfn); 108 } 109 110 int __ip_local_out(struct sk_buff *skb) 111 { 112 return __ip_local_out_sk(skb->sk, skb); 113 } 114 115 int ip_local_out_sk(struct sock *sk, struct sk_buff *skb) 116 { 117 int err; 118 119 err = __ip_local_out(skb); 120 if (likely(err == 1)) 121 err = dst_output(sk, skb); 122 123 return err; 124 } 125 EXPORT_SYMBOL_GPL(ip_local_out_sk); 126 127 static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst) 128 { 129 int ttl = inet->uc_ttl; 130 131 if (ttl < 0) 132 ttl = ip4_dst_hoplimit(dst); 133 return ttl; 134 } 135 136 /* 137 * Add an ip header to a skbuff and send it out. 138 * 139 */ 140 int ip_build_and_send_pkt(struct sk_buff *skb, const struct sock *sk, 141 __be32 saddr, __be32 daddr, struct ip_options_rcu *opt) 142 { 143 struct inet_sock *inet = inet_sk(sk); 144 struct rtable *rt = skb_rtable(skb); 145 struct iphdr *iph; 146 147 /* Build the IP header. */ 148 skb_push(skb, sizeof(struct iphdr) + (opt ? opt->opt.optlen : 0)); 149 skb_reset_network_header(skb); 150 iph = ip_hdr(skb); 151 iph->version = 4; 152 iph->ihl = 5; 153 iph->tos = inet->tos; 154 iph->ttl = ip_select_ttl(inet, &rt->dst); 155 iph->daddr = (opt && opt->opt.srr ? opt->opt.faddr : daddr); 156 iph->saddr = saddr; 157 iph->protocol = sk->sk_protocol; 158 if (ip_dont_fragment(sk, &rt->dst)) { 159 iph->frag_off = htons(IP_DF); 160 iph->id = 0; 161 } else { 162 iph->frag_off = 0; 163 __ip_select_ident(sock_net(sk), iph, 1); 164 } 165 166 if (opt && opt->opt.optlen) { 167 iph->ihl += opt->opt.optlen>>2; 168 ip_options_build(skb, &opt->opt, daddr, rt, 0); 169 } 170 171 skb->priority = sk->sk_priority; 172 skb->mark = sk->sk_mark; 173 174 /* Send it out. */ 175 return ip_local_out(skb); 176 } 177 EXPORT_SYMBOL_GPL(ip_build_and_send_pkt); 178 179 static int ip_finish_output2(struct sock *sk, struct sk_buff *skb) 180 { 181 struct dst_entry *dst = skb_dst(skb); 182 struct rtable *rt = (struct rtable *)dst; 183 struct net_device *dev = dst->dev; 184 struct net *net = dev_net(dev); 185 unsigned int hh_len = LL_RESERVED_SPACE(dev); 186 struct neighbour *neigh; 187 u32 nexthop; 188 189 if (rt->rt_type == RTN_MULTICAST) { 190 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUTMCAST, skb->len); 191 } else if (rt->rt_type == RTN_BROADCAST) 192 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUTBCAST, skb->len); 193 194 /* Be paranoid, rather than too clever. */ 195 if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) { 196 struct sk_buff *skb2; 197 198 skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev)); 199 if (!skb2) { 200 kfree_skb(skb); 201 return -ENOMEM; 202 } 203 if (skb->sk) 204 skb_set_owner_w(skb2, skb->sk); 205 consume_skb(skb); 206 skb = skb2; 207 } 208 209 rcu_read_lock_bh(); 210 nexthop = (__force u32) rt_nexthop(rt, ip_hdr(skb)->daddr); 211 neigh = __ipv4_neigh_lookup_noref(dev, nexthop); 212 if (unlikely(!neigh)) 213 neigh = __neigh_create(&arp_tbl, &nexthop, dev, false); 214 if (!IS_ERR(neigh)) { 215 int res = dst_neigh_output(dst, neigh, skb); 216 217 rcu_read_unlock_bh(); 218 return res; 219 } 220 rcu_read_unlock_bh(); 221 222 net_dbg_ratelimited("%s: No header cache and no neighbour!\n", 223 __func__); 224 kfree_skb(skb); 225 return -EINVAL; 226 } 227 228 static int ip_finish_output_gso(struct sock *sk, struct sk_buff *skb, 229 unsigned int mtu) 230 { 231 netdev_features_t features; 232 struct sk_buff *segs; 233 int ret = 0; 234 235 /* common case: locally created skb or seglen is <= mtu */ 236 if (((IPCB(skb)->flags & IPSKB_FORWARDED) == 0) || 237 skb_gso_network_seglen(skb) <= mtu) 238 return ip_finish_output2(sk, skb); 239 240 /* Slowpath - GSO segment length is exceeding the dst MTU. 241 * 242 * This can happen in two cases: 243 * 1) TCP GRO packet, DF bit not set 244 * 2) skb arrived via virtio-net, we thus get TSO/GSO skbs directly 245 * from host network stack. 246 */ 247 features = netif_skb_features(skb); 248 segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK); 249 if (IS_ERR_OR_NULL(segs)) { 250 kfree_skb(skb); 251 return -ENOMEM; 252 } 253 254 consume_skb(skb); 255 256 do { 257 struct sk_buff *nskb = segs->next; 258 int err; 259 260 segs->next = NULL; 261 err = ip_fragment(sk, segs, mtu, ip_finish_output2); 262 263 if (err && ret == 0) 264 ret = err; 265 segs = nskb; 266 } while (segs); 267 268 return ret; 269 } 270 271 static int ip_finish_output(struct net *net, struct sock *sk, struct sk_buff *skb) 272 { 273 unsigned int mtu; 274 275 #if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM) 276 /* Policy lookup after SNAT yielded a new policy */ 277 if (skb_dst(skb)->xfrm) { 278 IPCB(skb)->flags |= IPSKB_REROUTED; 279 return dst_output(sk, skb); 280 } 281 #endif 282 mtu = ip_skb_dst_mtu(skb); 283 if (skb_is_gso(skb)) 284 return ip_finish_output_gso(sk, skb, mtu); 285 286 if (skb->len > mtu || (IPCB(skb)->flags & IPSKB_FRAG_PMTU)) 287 return ip_fragment(sk, skb, mtu, ip_finish_output2); 288 289 return ip_finish_output2(sk, skb); 290 } 291 292 int ip_mc_output(struct sock *sk, struct sk_buff *skb) 293 { 294 struct rtable *rt = skb_rtable(skb); 295 struct net_device *dev = rt->dst.dev; 296 struct net *net = dev_net(dev); 297 298 /* 299 * If the indicated interface is up and running, send the packet. 300 */ 301 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUT, skb->len); 302 303 skb->dev = dev; 304 skb->protocol = htons(ETH_P_IP); 305 306 /* 307 * Multicasts are looped back for other local users 308 */ 309 310 if (rt->rt_flags&RTCF_MULTICAST) { 311 if (sk_mc_loop(sk) 312 #ifdef CONFIG_IP_MROUTE 313 /* Small optimization: do not loopback not local frames, 314 which returned after forwarding; they will be dropped 315 by ip_mr_input in any case. 316 Note, that local frames are looped back to be delivered 317 to local recipients. 318 319 This check is duplicated in ip_mr_input at the moment. 320 */ 321 && 322 ((rt->rt_flags & RTCF_LOCAL) || 323 !(IPCB(skb)->flags & IPSKB_FORWARDED)) 324 #endif 325 ) { 326 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC); 327 if (newskb) 328 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, 329 net, sk, newskb, NULL, newskb->dev, 330 dev_loopback_xmit); 331 } 332 333 /* Multicasts with ttl 0 must not go beyond the host */ 334 335 if (ip_hdr(skb)->ttl == 0) { 336 kfree_skb(skb); 337 return 0; 338 } 339 } 340 341 if (rt->rt_flags&RTCF_BROADCAST) { 342 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC); 343 if (newskb) 344 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, 345 net, sk, newskb, NULL, newskb->dev, 346 dev_loopback_xmit); 347 } 348 349 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, 350 net, sk, skb, NULL, skb->dev, 351 ip_finish_output, 352 !(IPCB(skb)->flags & IPSKB_REROUTED)); 353 } 354 355 int ip_output(struct sock *sk, struct sk_buff *skb) 356 { 357 struct net_device *dev = skb_dst(skb)->dev; 358 struct net *net = dev_net(dev); 359 360 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUT, skb->len); 361 362 skb->dev = dev; 363 skb->protocol = htons(ETH_P_IP); 364 365 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, 366 net, sk, skb, NULL, dev, 367 ip_finish_output, 368 !(IPCB(skb)->flags & IPSKB_REROUTED)); 369 } 370 371 /* 372 * copy saddr and daddr, possibly using 64bit load/stores 373 * Equivalent to : 374 * iph->saddr = fl4->saddr; 375 * iph->daddr = fl4->daddr; 376 */ 377 static void ip_copy_addrs(struct iphdr *iph, const struct flowi4 *fl4) 378 { 379 BUILD_BUG_ON(offsetof(typeof(*fl4), daddr) != 380 offsetof(typeof(*fl4), saddr) + sizeof(fl4->saddr)); 381 memcpy(&iph->saddr, &fl4->saddr, 382 sizeof(fl4->saddr) + sizeof(fl4->daddr)); 383 } 384 385 /* Note: skb->sk can be different from sk, in case of tunnels */ 386 int ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl) 387 { 388 struct inet_sock *inet = inet_sk(sk); 389 struct ip_options_rcu *inet_opt; 390 struct flowi4 *fl4; 391 struct rtable *rt; 392 struct iphdr *iph; 393 int res; 394 395 /* Skip all of this if the packet is already routed, 396 * f.e. by something like SCTP. 397 */ 398 rcu_read_lock(); 399 inet_opt = rcu_dereference(inet->inet_opt); 400 fl4 = &fl->u.ip4; 401 rt = skb_rtable(skb); 402 if (rt) 403 goto packet_routed; 404 405 /* Make sure we can route this packet. */ 406 rt = (struct rtable *)__sk_dst_check(sk, 0); 407 if (!rt) { 408 __be32 daddr; 409 410 /* Use correct destination address if we have options. */ 411 daddr = inet->inet_daddr; 412 if (inet_opt && inet_opt->opt.srr) 413 daddr = inet_opt->opt.faddr; 414 415 /* If this fails, retransmit mechanism of transport layer will 416 * keep trying until route appears or the connection times 417 * itself out. 418 */ 419 rt = ip_route_output_ports(sock_net(sk), fl4, sk, 420 daddr, inet->inet_saddr, 421 inet->inet_dport, 422 inet->inet_sport, 423 sk->sk_protocol, 424 RT_CONN_FLAGS(sk), 425 sk->sk_bound_dev_if); 426 if (IS_ERR(rt)) 427 goto no_route; 428 sk_setup_caps(sk, &rt->dst); 429 } 430 skb_dst_set_noref(skb, &rt->dst); 431 432 packet_routed: 433 if (inet_opt && inet_opt->opt.is_strictroute && rt->rt_uses_gateway) 434 goto no_route; 435 436 /* OK, we know where to send it, allocate and build IP header. */ 437 skb_push(skb, sizeof(struct iphdr) + (inet_opt ? inet_opt->opt.optlen : 0)); 438 skb_reset_network_header(skb); 439 iph = ip_hdr(skb); 440 *((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (inet->tos & 0xff)); 441 if (ip_dont_fragment(sk, &rt->dst) && !skb->ignore_df) 442 iph->frag_off = htons(IP_DF); 443 else 444 iph->frag_off = 0; 445 iph->ttl = ip_select_ttl(inet, &rt->dst); 446 iph->protocol = sk->sk_protocol; 447 ip_copy_addrs(iph, fl4); 448 449 /* Transport layer set skb->h.foo itself. */ 450 451 if (inet_opt && inet_opt->opt.optlen) { 452 iph->ihl += inet_opt->opt.optlen >> 2; 453 ip_options_build(skb, &inet_opt->opt, inet->inet_daddr, rt, 0); 454 } 455 456 ip_select_ident_segs(sock_net(sk), skb, sk, 457 skb_shinfo(skb)->gso_segs ?: 1); 458 459 /* TODO : should we use skb->sk here instead of sk ? */ 460 skb->priority = sk->sk_priority; 461 skb->mark = sk->sk_mark; 462 463 res = ip_local_out(skb); 464 rcu_read_unlock(); 465 return res; 466 467 no_route: 468 rcu_read_unlock(); 469 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES); 470 kfree_skb(skb); 471 return -EHOSTUNREACH; 472 } 473 EXPORT_SYMBOL(ip_queue_xmit); 474 475 static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from) 476 { 477 to->pkt_type = from->pkt_type; 478 to->priority = from->priority; 479 to->protocol = from->protocol; 480 skb_dst_drop(to); 481 skb_dst_copy(to, from); 482 to->dev = from->dev; 483 to->mark = from->mark; 484 485 /* Copy the flags to each fragment. */ 486 IPCB(to)->flags = IPCB(from)->flags; 487 488 #ifdef CONFIG_NET_SCHED 489 to->tc_index = from->tc_index; 490 #endif 491 nf_copy(to, from); 492 #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE) 493 to->ipvs_property = from->ipvs_property; 494 #endif 495 skb_copy_secmark(to, from); 496 } 497 498 static int ip_fragment(struct sock *sk, struct sk_buff *skb, 499 unsigned int mtu, 500 int (*output)(struct sock *, struct sk_buff *)) 501 { 502 struct iphdr *iph = ip_hdr(skb); 503 504 if ((iph->frag_off & htons(IP_DF)) == 0) 505 return ip_do_fragment(sk, skb, output); 506 507 if (unlikely(!skb->ignore_df || 508 (IPCB(skb)->frag_max_size && 509 IPCB(skb)->frag_max_size > mtu))) { 510 struct net *net = dev_net(skb_rtable(skb)->dst.dev); 511 512 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS); 513 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, 514 htonl(mtu)); 515 kfree_skb(skb); 516 return -EMSGSIZE; 517 } 518 519 return ip_do_fragment(sk, skb, output); 520 } 521 522 /* 523 * This IP datagram is too large to be sent in one piece. Break it up into 524 * smaller pieces (each of size equal to IP header plus 525 * a block of the data of the original IP data part) that will yet fit in a 526 * single device frame, and queue such a frame for sending. 527 */ 528 529 int ip_do_fragment(struct sock *sk, struct sk_buff *skb, 530 int (*output)(struct sock *, struct sk_buff *)) 531 { 532 struct iphdr *iph; 533 int ptr; 534 struct net_device *dev; 535 struct sk_buff *skb2; 536 unsigned int mtu, hlen, left, len, ll_rs; 537 int offset; 538 __be16 not_last_frag; 539 struct rtable *rt = skb_rtable(skb); 540 struct net *net; 541 int err = 0; 542 543 dev = rt->dst.dev; 544 net = dev_net(dev); 545 546 /* 547 * Point into the IP datagram header. 548 */ 549 550 iph = ip_hdr(skb); 551 552 mtu = ip_skb_dst_mtu(skb); 553 if (IPCB(skb)->frag_max_size && IPCB(skb)->frag_max_size < mtu) 554 mtu = IPCB(skb)->frag_max_size; 555 556 /* 557 * Setup starting values. 558 */ 559 560 hlen = iph->ihl * 4; 561 mtu = mtu - hlen; /* Size of data space */ 562 IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE; 563 564 /* When frag_list is given, use it. First, check its validity: 565 * some transformers could create wrong frag_list or break existing 566 * one, it is not prohibited. In this case fall back to copying. 567 * 568 * LATER: this step can be merged to real generation of fragments, 569 * we can switch to copy when see the first bad fragment. 570 */ 571 if (skb_has_frag_list(skb)) { 572 struct sk_buff *frag, *frag2; 573 int first_len = skb_pagelen(skb); 574 575 if (first_len - hlen > mtu || 576 ((first_len - hlen) & 7) || 577 ip_is_fragment(iph) || 578 skb_cloned(skb)) 579 goto slow_path; 580 581 skb_walk_frags(skb, frag) { 582 /* Correct geometry. */ 583 if (frag->len > mtu || 584 ((frag->len & 7) && frag->next) || 585 skb_headroom(frag) < hlen) 586 goto slow_path_clean; 587 588 /* Partially cloned skb? */ 589 if (skb_shared(frag)) 590 goto slow_path_clean; 591 592 BUG_ON(frag->sk); 593 if (skb->sk) { 594 frag->sk = skb->sk; 595 frag->destructor = sock_wfree; 596 } 597 skb->truesize -= frag->truesize; 598 } 599 600 /* Everything is OK. Generate! */ 601 602 err = 0; 603 offset = 0; 604 frag = skb_shinfo(skb)->frag_list; 605 skb_frag_list_init(skb); 606 skb->data_len = first_len - skb_headlen(skb); 607 skb->len = first_len; 608 iph->tot_len = htons(first_len); 609 iph->frag_off = htons(IP_MF); 610 ip_send_check(iph); 611 612 for (;;) { 613 /* Prepare header of the next frame, 614 * before previous one went down. */ 615 if (frag) { 616 frag->ip_summed = CHECKSUM_NONE; 617 skb_reset_transport_header(frag); 618 __skb_push(frag, hlen); 619 skb_reset_network_header(frag); 620 memcpy(skb_network_header(frag), iph, hlen); 621 iph = ip_hdr(frag); 622 iph->tot_len = htons(frag->len); 623 ip_copy_metadata(frag, skb); 624 if (offset == 0) 625 ip_options_fragment(frag); 626 offset += skb->len - hlen; 627 iph->frag_off = htons(offset>>3); 628 if (frag->next) 629 iph->frag_off |= htons(IP_MF); 630 /* Ready, complete checksum */ 631 ip_send_check(iph); 632 } 633 634 err = output(sk, skb); 635 636 if (!err) 637 IP_INC_STATS(net, IPSTATS_MIB_FRAGCREATES); 638 if (err || !frag) 639 break; 640 641 skb = frag; 642 frag = skb->next; 643 skb->next = NULL; 644 } 645 646 if (err == 0) { 647 IP_INC_STATS(net, IPSTATS_MIB_FRAGOKS); 648 return 0; 649 } 650 651 while (frag) { 652 skb = frag->next; 653 kfree_skb(frag); 654 frag = skb; 655 } 656 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS); 657 return err; 658 659 slow_path_clean: 660 skb_walk_frags(skb, frag2) { 661 if (frag2 == frag) 662 break; 663 frag2->sk = NULL; 664 frag2->destructor = NULL; 665 skb->truesize += frag2->truesize; 666 } 667 } 668 669 slow_path: 670 /* for offloaded checksums cleanup checksum before fragmentation */ 671 if ((skb->ip_summed == CHECKSUM_PARTIAL) && skb_checksum_help(skb)) 672 goto fail; 673 iph = ip_hdr(skb); 674 675 left = skb->len - hlen; /* Space per frame */ 676 ptr = hlen; /* Where to start from */ 677 678 ll_rs = LL_RESERVED_SPACE(rt->dst.dev); 679 680 /* 681 * Fragment the datagram. 682 */ 683 684 offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3; 685 not_last_frag = iph->frag_off & htons(IP_MF); 686 687 /* 688 * Keep copying data until we run out. 689 */ 690 691 while (left > 0) { 692 len = left; 693 /* IF: it doesn't fit, use 'mtu' - the data space left */ 694 if (len > mtu) 695 len = mtu; 696 /* IF: we are not sending up to and including the packet end 697 then align the next start on an eight byte boundary */ 698 if (len < left) { 699 len &= ~7; 700 } 701 702 /* Allocate buffer */ 703 skb2 = alloc_skb(len + hlen + ll_rs, GFP_ATOMIC); 704 if (!skb2) { 705 err = -ENOMEM; 706 goto fail; 707 } 708 709 /* 710 * Set up data on packet 711 */ 712 713 ip_copy_metadata(skb2, skb); 714 skb_reserve(skb2, ll_rs); 715 skb_put(skb2, len + hlen); 716 skb_reset_network_header(skb2); 717 skb2->transport_header = skb2->network_header + hlen; 718 719 /* 720 * Charge the memory for the fragment to any owner 721 * it might possess 722 */ 723 724 if (skb->sk) 725 skb_set_owner_w(skb2, skb->sk); 726 727 /* 728 * Copy the packet header into the new buffer. 729 */ 730 731 skb_copy_from_linear_data(skb, skb_network_header(skb2), hlen); 732 733 /* 734 * Copy a block of the IP datagram. 735 */ 736 if (skb_copy_bits(skb, ptr, skb_transport_header(skb2), len)) 737 BUG(); 738 left -= len; 739 740 /* 741 * Fill in the new header fields. 742 */ 743 iph = ip_hdr(skb2); 744 iph->frag_off = htons((offset >> 3)); 745 746 if (IPCB(skb)->flags & IPSKB_FRAG_PMTU) 747 iph->frag_off |= htons(IP_DF); 748 749 /* ANK: dirty, but effective trick. Upgrade options only if 750 * the segment to be fragmented was THE FIRST (otherwise, 751 * options are already fixed) and make it ONCE 752 * on the initial skb, so that all the following fragments 753 * will inherit fixed options. 754 */ 755 if (offset == 0) 756 ip_options_fragment(skb); 757 758 /* 759 * Added AC : If we are fragmenting a fragment that's not the 760 * last fragment then keep MF on each bit 761 */ 762 if (left > 0 || not_last_frag) 763 iph->frag_off |= htons(IP_MF); 764 ptr += len; 765 offset += len; 766 767 /* 768 * Put this fragment into the sending queue. 769 */ 770 iph->tot_len = htons(len + hlen); 771 772 ip_send_check(iph); 773 774 err = output(sk, skb2); 775 if (err) 776 goto fail; 777 778 IP_INC_STATS(net, IPSTATS_MIB_FRAGCREATES); 779 } 780 consume_skb(skb); 781 IP_INC_STATS(net, IPSTATS_MIB_FRAGOKS); 782 return err; 783 784 fail: 785 kfree_skb(skb); 786 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS); 787 return err; 788 } 789 EXPORT_SYMBOL(ip_do_fragment); 790 791 int 792 ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb) 793 { 794 struct msghdr *msg = from; 795 796 if (skb->ip_summed == CHECKSUM_PARTIAL) { 797 if (copy_from_iter(to, len, &msg->msg_iter) != len) 798 return -EFAULT; 799 } else { 800 __wsum csum = 0; 801 if (csum_and_copy_from_iter(to, len, &csum, &msg->msg_iter) != len) 802 return -EFAULT; 803 skb->csum = csum_block_add(skb->csum, csum, odd); 804 } 805 return 0; 806 } 807 EXPORT_SYMBOL(ip_generic_getfrag); 808 809 static inline __wsum 810 csum_page(struct page *page, int offset, int copy) 811 { 812 char *kaddr; 813 __wsum csum; 814 kaddr = kmap(page); 815 csum = csum_partial(kaddr + offset, copy, 0); 816 kunmap(page); 817 return csum; 818 } 819 820 static inline int ip_ufo_append_data(struct sock *sk, 821 struct sk_buff_head *queue, 822 int getfrag(void *from, char *to, int offset, int len, 823 int odd, struct sk_buff *skb), 824 void *from, int length, int hh_len, int fragheaderlen, 825 int transhdrlen, int maxfraglen, unsigned int flags) 826 { 827 struct sk_buff *skb; 828 int err; 829 830 /* There is support for UDP fragmentation offload by network 831 * device, so create one single skb packet containing complete 832 * udp datagram 833 */ 834 skb = skb_peek_tail(queue); 835 if (!skb) { 836 skb = sock_alloc_send_skb(sk, 837 hh_len + fragheaderlen + transhdrlen + 20, 838 (flags & MSG_DONTWAIT), &err); 839 840 if (!skb) 841 return err; 842 843 /* reserve space for Hardware header */ 844 skb_reserve(skb, hh_len); 845 846 /* create space for UDP/IP header */ 847 skb_put(skb, fragheaderlen + transhdrlen); 848 849 /* initialize network header pointer */ 850 skb_reset_network_header(skb); 851 852 /* initialize protocol header pointer */ 853 skb->transport_header = skb->network_header + fragheaderlen; 854 855 skb->csum = 0; 856 857 __skb_queue_tail(queue, skb); 858 } else if (skb_is_gso(skb)) { 859 goto append; 860 } 861 862 skb->ip_summed = CHECKSUM_PARTIAL; 863 /* specify the length of each IP datagram fragment */ 864 skb_shinfo(skb)->gso_size = maxfraglen - fragheaderlen; 865 skb_shinfo(skb)->gso_type = SKB_GSO_UDP; 866 867 append: 868 return skb_append_datato_frags(sk, skb, getfrag, from, 869 (length - transhdrlen)); 870 } 871 872 static int __ip_append_data(struct sock *sk, 873 struct flowi4 *fl4, 874 struct sk_buff_head *queue, 875 struct inet_cork *cork, 876 struct page_frag *pfrag, 877 int getfrag(void *from, char *to, int offset, 878 int len, int odd, struct sk_buff *skb), 879 void *from, int length, int transhdrlen, 880 unsigned int flags) 881 { 882 struct inet_sock *inet = inet_sk(sk); 883 struct sk_buff *skb; 884 885 struct ip_options *opt = cork->opt; 886 int hh_len; 887 int exthdrlen; 888 int mtu; 889 int copy; 890 int err; 891 int offset = 0; 892 unsigned int maxfraglen, fragheaderlen, maxnonfragsize; 893 int csummode = CHECKSUM_NONE; 894 struct rtable *rt = (struct rtable *)cork->dst; 895 u32 tskey = 0; 896 897 skb = skb_peek_tail(queue); 898 899 exthdrlen = !skb ? rt->dst.header_len : 0; 900 mtu = cork->fragsize; 901 if (cork->tx_flags & SKBTX_ANY_SW_TSTAMP && 902 sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID) 903 tskey = sk->sk_tskey++; 904 905 hh_len = LL_RESERVED_SPACE(rt->dst.dev); 906 907 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0); 908 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen; 909 maxnonfragsize = ip_sk_ignore_df(sk) ? 0xFFFF : mtu; 910 911 if (cork->length + length > maxnonfragsize - fragheaderlen) { 912 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport, 913 mtu - (opt ? opt->optlen : 0)); 914 return -EMSGSIZE; 915 } 916 917 /* 918 * transhdrlen > 0 means that this is the first fragment and we wish 919 * it won't be fragmented in the future. 920 */ 921 if (transhdrlen && 922 length + fragheaderlen <= mtu && 923 rt->dst.dev->features & NETIF_F_V4_CSUM && 924 !exthdrlen) 925 csummode = CHECKSUM_PARTIAL; 926 927 cork->length += length; 928 if (((length > mtu) || (skb && skb_is_gso(skb))) && 929 (sk->sk_protocol == IPPROTO_UDP) && 930 (rt->dst.dev->features & NETIF_F_UFO) && !rt->dst.header_len && 931 (sk->sk_type == SOCK_DGRAM)) { 932 err = ip_ufo_append_data(sk, queue, getfrag, from, length, 933 hh_len, fragheaderlen, transhdrlen, 934 maxfraglen, flags); 935 if (err) 936 goto error; 937 return 0; 938 } 939 940 /* So, what's going on in the loop below? 941 * 942 * We use calculated fragment length to generate chained skb, 943 * each of segments is IP fragment ready for sending to network after 944 * adding appropriate IP header. 945 */ 946 947 if (!skb) 948 goto alloc_new_skb; 949 950 while (length > 0) { 951 /* Check if the remaining data fits into current packet. */ 952 copy = mtu - skb->len; 953 if (copy < length) 954 copy = maxfraglen - skb->len; 955 if (copy <= 0) { 956 char *data; 957 unsigned int datalen; 958 unsigned int fraglen; 959 unsigned int fraggap; 960 unsigned int alloclen; 961 struct sk_buff *skb_prev; 962 alloc_new_skb: 963 skb_prev = skb; 964 if (skb_prev) 965 fraggap = skb_prev->len - maxfraglen; 966 else 967 fraggap = 0; 968 969 /* 970 * If remaining data exceeds the mtu, 971 * we know we need more fragment(s). 972 */ 973 datalen = length + fraggap; 974 if (datalen > mtu - fragheaderlen) 975 datalen = maxfraglen - fragheaderlen; 976 fraglen = datalen + fragheaderlen; 977 978 if ((flags & MSG_MORE) && 979 !(rt->dst.dev->features&NETIF_F_SG)) 980 alloclen = mtu; 981 else 982 alloclen = fraglen; 983 984 alloclen += exthdrlen; 985 986 /* The last fragment gets additional space at tail. 987 * Note, with MSG_MORE we overallocate on fragments, 988 * because we have no idea what fragment will be 989 * the last. 990 */ 991 if (datalen == length + fraggap) 992 alloclen += rt->dst.trailer_len; 993 994 if (transhdrlen) { 995 skb = sock_alloc_send_skb(sk, 996 alloclen + hh_len + 15, 997 (flags & MSG_DONTWAIT), &err); 998 } else { 999 skb = NULL; 1000 if (atomic_read(&sk->sk_wmem_alloc) <= 1001 2 * sk->sk_sndbuf) 1002 skb = sock_wmalloc(sk, 1003 alloclen + hh_len + 15, 1, 1004 sk->sk_allocation); 1005 if (unlikely(!skb)) 1006 err = -ENOBUFS; 1007 } 1008 if (!skb) 1009 goto error; 1010 1011 /* 1012 * Fill in the control structures 1013 */ 1014 skb->ip_summed = csummode; 1015 skb->csum = 0; 1016 skb_reserve(skb, hh_len); 1017 1018 /* only the initial fragment is time stamped */ 1019 skb_shinfo(skb)->tx_flags = cork->tx_flags; 1020 cork->tx_flags = 0; 1021 skb_shinfo(skb)->tskey = tskey; 1022 tskey = 0; 1023 1024 /* 1025 * Find where to start putting bytes. 1026 */ 1027 data = skb_put(skb, fraglen + exthdrlen); 1028 skb_set_network_header(skb, exthdrlen); 1029 skb->transport_header = (skb->network_header + 1030 fragheaderlen); 1031 data += fragheaderlen + exthdrlen; 1032 1033 if (fraggap) { 1034 skb->csum = skb_copy_and_csum_bits( 1035 skb_prev, maxfraglen, 1036 data + transhdrlen, fraggap, 0); 1037 skb_prev->csum = csum_sub(skb_prev->csum, 1038 skb->csum); 1039 data += fraggap; 1040 pskb_trim_unique(skb_prev, maxfraglen); 1041 } 1042 1043 copy = datalen - transhdrlen - fraggap; 1044 if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) { 1045 err = -EFAULT; 1046 kfree_skb(skb); 1047 goto error; 1048 } 1049 1050 offset += copy; 1051 length -= datalen - fraggap; 1052 transhdrlen = 0; 1053 exthdrlen = 0; 1054 csummode = CHECKSUM_NONE; 1055 1056 /* 1057 * Put the packet on the pending queue. 1058 */ 1059 __skb_queue_tail(queue, skb); 1060 continue; 1061 } 1062 1063 if (copy > length) 1064 copy = length; 1065 1066 if (!(rt->dst.dev->features&NETIF_F_SG)) { 1067 unsigned int off; 1068 1069 off = skb->len; 1070 if (getfrag(from, skb_put(skb, copy), 1071 offset, copy, off, skb) < 0) { 1072 __skb_trim(skb, off); 1073 err = -EFAULT; 1074 goto error; 1075 } 1076 } else { 1077 int i = skb_shinfo(skb)->nr_frags; 1078 1079 err = -ENOMEM; 1080 if (!sk_page_frag_refill(sk, pfrag)) 1081 goto error; 1082 1083 if (!skb_can_coalesce(skb, i, pfrag->page, 1084 pfrag->offset)) { 1085 err = -EMSGSIZE; 1086 if (i == MAX_SKB_FRAGS) 1087 goto error; 1088 1089 __skb_fill_page_desc(skb, i, pfrag->page, 1090 pfrag->offset, 0); 1091 skb_shinfo(skb)->nr_frags = ++i; 1092 get_page(pfrag->page); 1093 } 1094 copy = min_t(int, copy, pfrag->size - pfrag->offset); 1095 if (getfrag(from, 1096 page_address(pfrag->page) + pfrag->offset, 1097 offset, copy, skb->len, skb) < 0) 1098 goto error_efault; 1099 1100 pfrag->offset += copy; 1101 skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy); 1102 skb->len += copy; 1103 skb->data_len += copy; 1104 skb->truesize += copy; 1105 atomic_add(copy, &sk->sk_wmem_alloc); 1106 } 1107 offset += copy; 1108 length -= copy; 1109 } 1110 1111 return 0; 1112 1113 error_efault: 1114 err = -EFAULT; 1115 error: 1116 cork->length -= length; 1117 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS); 1118 return err; 1119 } 1120 1121 static int ip_setup_cork(struct sock *sk, struct inet_cork *cork, 1122 struct ipcm_cookie *ipc, struct rtable **rtp) 1123 { 1124 struct ip_options_rcu *opt; 1125 struct rtable *rt; 1126 1127 /* 1128 * setup for corking. 1129 */ 1130 opt = ipc->opt; 1131 if (opt) { 1132 if (!cork->opt) { 1133 cork->opt = kmalloc(sizeof(struct ip_options) + 40, 1134 sk->sk_allocation); 1135 if (unlikely(!cork->opt)) 1136 return -ENOBUFS; 1137 } 1138 memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen); 1139 cork->flags |= IPCORK_OPT; 1140 cork->addr = ipc->addr; 1141 } 1142 rt = *rtp; 1143 if (unlikely(!rt)) 1144 return -EFAULT; 1145 /* 1146 * We steal reference to this route, caller should not release it 1147 */ 1148 *rtp = NULL; 1149 cork->fragsize = ip_sk_use_pmtu(sk) ? 1150 dst_mtu(&rt->dst) : rt->dst.dev->mtu; 1151 cork->dst = &rt->dst; 1152 cork->length = 0; 1153 cork->ttl = ipc->ttl; 1154 cork->tos = ipc->tos; 1155 cork->priority = ipc->priority; 1156 cork->tx_flags = ipc->tx_flags; 1157 1158 return 0; 1159 } 1160 1161 /* 1162 * ip_append_data() and ip_append_page() can make one large IP datagram 1163 * from many pieces of data. Each pieces will be holded on the socket 1164 * until ip_push_pending_frames() is called. Each piece can be a page 1165 * or non-page data. 1166 * 1167 * Not only UDP, other transport protocols - e.g. raw sockets - can use 1168 * this interface potentially. 1169 * 1170 * LATER: length must be adjusted by pad at tail, when it is required. 1171 */ 1172 int ip_append_data(struct sock *sk, struct flowi4 *fl4, 1173 int getfrag(void *from, char *to, int offset, int len, 1174 int odd, struct sk_buff *skb), 1175 void *from, int length, int transhdrlen, 1176 struct ipcm_cookie *ipc, struct rtable **rtp, 1177 unsigned int flags) 1178 { 1179 struct inet_sock *inet = inet_sk(sk); 1180 int err; 1181 1182 if (flags&MSG_PROBE) 1183 return 0; 1184 1185 if (skb_queue_empty(&sk->sk_write_queue)) { 1186 err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp); 1187 if (err) 1188 return err; 1189 } else { 1190 transhdrlen = 0; 1191 } 1192 1193 return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base, 1194 sk_page_frag(sk), getfrag, 1195 from, length, transhdrlen, flags); 1196 } 1197 1198 ssize_t ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page, 1199 int offset, size_t size, int flags) 1200 { 1201 struct inet_sock *inet = inet_sk(sk); 1202 struct sk_buff *skb; 1203 struct rtable *rt; 1204 struct ip_options *opt = NULL; 1205 struct inet_cork *cork; 1206 int hh_len; 1207 int mtu; 1208 int len; 1209 int err; 1210 unsigned int maxfraglen, fragheaderlen, fraggap, maxnonfragsize; 1211 1212 if (inet->hdrincl) 1213 return -EPERM; 1214 1215 if (flags&MSG_PROBE) 1216 return 0; 1217 1218 if (skb_queue_empty(&sk->sk_write_queue)) 1219 return -EINVAL; 1220 1221 cork = &inet->cork.base; 1222 rt = (struct rtable *)cork->dst; 1223 if (cork->flags & IPCORK_OPT) 1224 opt = cork->opt; 1225 1226 if (!(rt->dst.dev->features&NETIF_F_SG)) 1227 return -EOPNOTSUPP; 1228 1229 hh_len = LL_RESERVED_SPACE(rt->dst.dev); 1230 mtu = cork->fragsize; 1231 1232 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0); 1233 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen; 1234 maxnonfragsize = ip_sk_ignore_df(sk) ? 0xFFFF : mtu; 1235 1236 if (cork->length + size > maxnonfragsize - fragheaderlen) { 1237 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport, 1238 mtu - (opt ? opt->optlen : 0)); 1239 return -EMSGSIZE; 1240 } 1241 1242 skb = skb_peek_tail(&sk->sk_write_queue); 1243 if (!skb) 1244 return -EINVAL; 1245 1246 cork->length += size; 1247 if ((size + skb->len > mtu) && 1248 (sk->sk_protocol == IPPROTO_UDP) && 1249 (rt->dst.dev->features & NETIF_F_UFO)) { 1250 skb_shinfo(skb)->gso_size = mtu - fragheaderlen; 1251 skb_shinfo(skb)->gso_type = SKB_GSO_UDP; 1252 } 1253 1254 while (size > 0) { 1255 if (skb_is_gso(skb)) { 1256 len = size; 1257 } else { 1258 1259 /* Check if the remaining data fits into current packet. */ 1260 len = mtu - skb->len; 1261 if (len < size) 1262 len = maxfraglen - skb->len; 1263 } 1264 if (len <= 0) { 1265 struct sk_buff *skb_prev; 1266 int alloclen; 1267 1268 skb_prev = skb; 1269 fraggap = skb_prev->len - maxfraglen; 1270 1271 alloclen = fragheaderlen + hh_len + fraggap + 15; 1272 skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation); 1273 if (unlikely(!skb)) { 1274 err = -ENOBUFS; 1275 goto error; 1276 } 1277 1278 /* 1279 * Fill in the control structures 1280 */ 1281 skb->ip_summed = CHECKSUM_NONE; 1282 skb->csum = 0; 1283 skb_reserve(skb, hh_len); 1284 1285 /* 1286 * Find where to start putting bytes. 1287 */ 1288 skb_put(skb, fragheaderlen + fraggap); 1289 skb_reset_network_header(skb); 1290 skb->transport_header = (skb->network_header + 1291 fragheaderlen); 1292 if (fraggap) { 1293 skb->csum = skb_copy_and_csum_bits(skb_prev, 1294 maxfraglen, 1295 skb_transport_header(skb), 1296 fraggap, 0); 1297 skb_prev->csum = csum_sub(skb_prev->csum, 1298 skb->csum); 1299 pskb_trim_unique(skb_prev, maxfraglen); 1300 } 1301 1302 /* 1303 * Put the packet on the pending queue. 1304 */ 1305 __skb_queue_tail(&sk->sk_write_queue, skb); 1306 continue; 1307 } 1308 1309 if (len > size) 1310 len = size; 1311 1312 if (skb_append_pagefrags(skb, page, offset, len)) { 1313 err = -EMSGSIZE; 1314 goto error; 1315 } 1316 1317 if (skb->ip_summed == CHECKSUM_NONE) { 1318 __wsum csum; 1319 csum = csum_page(page, offset, len); 1320 skb->csum = csum_block_add(skb->csum, csum, skb->len); 1321 } 1322 1323 skb->len += len; 1324 skb->data_len += len; 1325 skb->truesize += len; 1326 atomic_add(len, &sk->sk_wmem_alloc); 1327 offset += len; 1328 size -= len; 1329 } 1330 return 0; 1331 1332 error: 1333 cork->length -= size; 1334 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS); 1335 return err; 1336 } 1337 1338 static void ip_cork_release(struct inet_cork *cork) 1339 { 1340 cork->flags &= ~IPCORK_OPT; 1341 kfree(cork->opt); 1342 cork->opt = NULL; 1343 dst_release(cork->dst); 1344 cork->dst = NULL; 1345 } 1346 1347 /* 1348 * Combined all pending IP fragments on the socket as one IP datagram 1349 * and push them out. 1350 */ 1351 struct sk_buff *__ip_make_skb(struct sock *sk, 1352 struct flowi4 *fl4, 1353 struct sk_buff_head *queue, 1354 struct inet_cork *cork) 1355 { 1356 struct sk_buff *skb, *tmp_skb; 1357 struct sk_buff **tail_skb; 1358 struct inet_sock *inet = inet_sk(sk); 1359 struct net *net = sock_net(sk); 1360 struct ip_options *opt = NULL; 1361 struct rtable *rt = (struct rtable *)cork->dst; 1362 struct iphdr *iph; 1363 __be16 df = 0; 1364 __u8 ttl; 1365 1366 skb = __skb_dequeue(queue); 1367 if (!skb) 1368 goto out; 1369 tail_skb = &(skb_shinfo(skb)->frag_list); 1370 1371 /* move skb->data to ip header from ext header */ 1372 if (skb->data < skb_network_header(skb)) 1373 __skb_pull(skb, skb_network_offset(skb)); 1374 while ((tmp_skb = __skb_dequeue(queue)) != NULL) { 1375 __skb_pull(tmp_skb, skb_network_header_len(skb)); 1376 *tail_skb = tmp_skb; 1377 tail_skb = &(tmp_skb->next); 1378 skb->len += tmp_skb->len; 1379 skb->data_len += tmp_skb->len; 1380 skb->truesize += tmp_skb->truesize; 1381 tmp_skb->destructor = NULL; 1382 tmp_skb->sk = NULL; 1383 } 1384 1385 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow 1386 * to fragment the frame generated here. No matter, what transforms 1387 * how transforms change size of the packet, it will come out. 1388 */ 1389 skb->ignore_df = ip_sk_ignore_df(sk); 1390 1391 /* DF bit is set when we want to see DF on outgoing frames. 1392 * If ignore_df is set too, we still allow to fragment this frame 1393 * locally. */ 1394 if (inet->pmtudisc == IP_PMTUDISC_DO || 1395 inet->pmtudisc == IP_PMTUDISC_PROBE || 1396 (skb->len <= dst_mtu(&rt->dst) && 1397 ip_dont_fragment(sk, &rt->dst))) 1398 df = htons(IP_DF); 1399 1400 if (cork->flags & IPCORK_OPT) 1401 opt = cork->opt; 1402 1403 if (cork->ttl != 0) 1404 ttl = cork->ttl; 1405 else if (rt->rt_type == RTN_MULTICAST) 1406 ttl = inet->mc_ttl; 1407 else 1408 ttl = ip_select_ttl(inet, &rt->dst); 1409 1410 iph = ip_hdr(skb); 1411 iph->version = 4; 1412 iph->ihl = 5; 1413 iph->tos = (cork->tos != -1) ? cork->tos : inet->tos; 1414 iph->frag_off = df; 1415 iph->ttl = ttl; 1416 iph->protocol = sk->sk_protocol; 1417 ip_copy_addrs(iph, fl4); 1418 ip_select_ident(net, skb, sk); 1419 1420 if (opt) { 1421 iph->ihl += opt->optlen>>2; 1422 ip_options_build(skb, opt, cork->addr, rt, 0); 1423 } 1424 1425 skb->priority = (cork->tos != -1) ? cork->priority: sk->sk_priority; 1426 skb->mark = sk->sk_mark; 1427 /* 1428 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec 1429 * on dst refcount 1430 */ 1431 cork->dst = NULL; 1432 skb_dst_set(skb, &rt->dst); 1433 1434 if (iph->protocol == IPPROTO_ICMP) 1435 icmp_out_count(net, ((struct icmphdr *) 1436 skb_transport_header(skb))->type); 1437 1438 ip_cork_release(cork); 1439 out: 1440 return skb; 1441 } 1442 1443 int ip_send_skb(struct net *net, struct sk_buff *skb) 1444 { 1445 int err; 1446 1447 err = ip_local_out(skb); 1448 if (err) { 1449 if (err > 0) 1450 err = net_xmit_errno(err); 1451 if (err) 1452 IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS); 1453 } 1454 1455 return err; 1456 } 1457 1458 int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4) 1459 { 1460 struct sk_buff *skb; 1461 1462 skb = ip_finish_skb(sk, fl4); 1463 if (!skb) 1464 return 0; 1465 1466 /* Netfilter gets whole the not fragmented skb. */ 1467 return ip_send_skb(sock_net(sk), skb); 1468 } 1469 1470 /* 1471 * Throw away all pending data on the socket. 1472 */ 1473 static void __ip_flush_pending_frames(struct sock *sk, 1474 struct sk_buff_head *queue, 1475 struct inet_cork *cork) 1476 { 1477 struct sk_buff *skb; 1478 1479 while ((skb = __skb_dequeue_tail(queue)) != NULL) 1480 kfree_skb(skb); 1481 1482 ip_cork_release(cork); 1483 } 1484 1485 void ip_flush_pending_frames(struct sock *sk) 1486 { 1487 __ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork.base); 1488 } 1489 1490 struct sk_buff *ip_make_skb(struct sock *sk, 1491 struct flowi4 *fl4, 1492 int getfrag(void *from, char *to, int offset, 1493 int len, int odd, struct sk_buff *skb), 1494 void *from, int length, int transhdrlen, 1495 struct ipcm_cookie *ipc, struct rtable **rtp, 1496 unsigned int flags) 1497 { 1498 struct inet_cork cork; 1499 struct sk_buff_head queue; 1500 int err; 1501 1502 if (flags & MSG_PROBE) 1503 return NULL; 1504 1505 __skb_queue_head_init(&queue); 1506 1507 cork.flags = 0; 1508 cork.addr = 0; 1509 cork.opt = NULL; 1510 err = ip_setup_cork(sk, &cork, ipc, rtp); 1511 if (err) 1512 return ERR_PTR(err); 1513 1514 err = __ip_append_data(sk, fl4, &queue, &cork, 1515 ¤t->task_frag, getfrag, 1516 from, length, transhdrlen, flags); 1517 if (err) { 1518 __ip_flush_pending_frames(sk, &queue, &cork); 1519 return ERR_PTR(err); 1520 } 1521 1522 return __ip_make_skb(sk, fl4, &queue, &cork); 1523 } 1524 1525 /* 1526 * Fetch data from kernel space and fill in checksum if needed. 1527 */ 1528 static int ip_reply_glue_bits(void *dptr, char *to, int offset, 1529 int len, int odd, struct sk_buff *skb) 1530 { 1531 __wsum csum; 1532 1533 csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0); 1534 skb->csum = csum_block_add(skb->csum, csum, odd); 1535 return 0; 1536 } 1537 1538 /* 1539 * Generic function to send a packet as reply to another packet. 1540 * Used to send some TCP resets/acks so far. 1541 */ 1542 void ip_send_unicast_reply(struct sock *sk, struct sk_buff *skb, 1543 const struct ip_options *sopt, 1544 __be32 daddr, __be32 saddr, 1545 const struct ip_reply_arg *arg, 1546 unsigned int len) 1547 { 1548 struct ip_options_data replyopts; 1549 struct ipcm_cookie ipc; 1550 struct flowi4 fl4; 1551 struct rtable *rt = skb_rtable(skb); 1552 struct net *net = sock_net(sk); 1553 struct sk_buff *nskb; 1554 int err; 1555 int oif; 1556 1557 if (__ip_options_echo(&replyopts.opt.opt, skb, sopt)) 1558 return; 1559 1560 ipc.addr = daddr; 1561 ipc.opt = NULL; 1562 ipc.tx_flags = 0; 1563 ipc.ttl = 0; 1564 ipc.tos = -1; 1565 1566 if (replyopts.opt.opt.optlen) { 1567 ipc.opt = &replyopts.opt; 1568 1569 if (replyopts.opt.opt.srr) 1570 daddr = replyopts.opt.opt.faddr; 1571 } 1572 1573 oif = arg->bound_dev_if; 1574 if (!oif && netif_index_is_l3_master(net, skb->skb_iif)) 1575 oif = skb->skb_iif; 1576 1577 flowi4_init_output(&fl4, oif, 1578 IP4_REPLY_MARK(net, skb->mark), 1579 RT_TOS(arg->tos), 1580 RT_SCOPE_UNIVERSE, ip_hdr(skb)->protocol, 1581 ip_reply_arg_flowi_flags(arg), 1582 daddr, saddr, 1583 tcp_hdr(skb)->source, tcp_hdr(skb)->dest); 1584 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4)); 1585 rt = ip_route_output_key(net, &fl4); 1586 if (IS_ERR(rt)) 1587 return; 1588 1589 inet_sk(sk)->tos = arg->tos; 1590 1591 sk->sk_priority = skb->priority; 1592 sk->sk_protocol = ip_hdr(skb)->protocol; 1593 sk->sk_bound_dev_if = arg->bound_dev_if; 1594 sk->sk_sndbuf = sysctl_wmem_default; 1595 err = ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base, 1596 len, 0, &ipc, &rt, MSG_DONTWAIT); 1597 if (unlikely(err)) { 1598 ip_flush_pending_frames(sk); 1599 goto out; 1600 } 1601 1602 nskb = skb_peek(&sk->sk_write_queue); 1603 if (nskb) { 1604 if (arg->csumoffset >= 0) 1605 *((__sum16 *)skb_transport_header(nskb) + 1606 arg->csumoffset) = csum_fold(csum_add(nskb->csum, 1607 arg->csum)); 1608 nskb->ip_summed = CHECKSUM_NONE; 1609 skb_set_queue_mapping(nskb, skb_get_queue_mapping(skb)); 1610 ip_push_pending_frames(sk, &fl4); 1611 } 1612 out: 1613 ip_rt_put(rt); 1614 } 1615 1616 void __init ip_init(void) 1617 { 1618 ip_rt_init(); 1619 inet_initpeers(); 1620 1621 #if defined(CONFIG_IP_MULTICAST) 1622 igmp_mc_init(); 1623 #endif 1624 } 1625