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