1/* 2 * INET An implementation of the TCP/IP protocol suite for the LINUX 3 * operating system. INET is implemented using the BSD Socket 4 * interface as the means of communication with the user level. 5 * 6 * The Internet Protocol (IP) output module. 7 * 8 * Authors: Ross Biro 9 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> 10 * Donald Becker, <becker@super.org> 11 * Alan Cox, <Alan.Cox@linux.org> 12 * Richard Underwood 13 * Stefan Becker, <stefanb@yello.ping.de> 14 * Jorge Cwik, <jorge@laser.satlink.net> 15 * Arnt Gulbrandsen, <agulbra@nvg.unit.no> 16 * Hirokazu Takahashi, <taka@valinux.co.jp> 17 * 18 * See ip_input.c for original log 19 * 20 * Fixes: 21 * Alan Cox : Missing nonblock feature in ip_build_xmit. 22 * Mike Kilburn : htons() missing in ip_build_xmit. 23 * Bradford Johnson: Fix faulty handling of some frames when 24 * no route is found. 25 * Alexander Demenshin: Missing sk/skb free in ip_queue_xmit 26 * (in case if packet not accepted by 27 * output firewall rules) 28 * Mike McLagan : Routing by source 29 * Alexey Kuznetsov: use new route cache 30 * Andi Kleen: Fix broken PMTU recovery and remove 31 * some redundant tests. 32 * Vitaly E. Lavrov : Transparent proxy revived after year coma. 33 * Andi Kleen : Replace ip_reply with ip_send_reply. 34 * Andi Kleen : Split fast and slow ip_build_xmit path 35 * for decreased register pressure on x86 36 * and more readibility. 37 * Marc Boucher : When call_out_firewall returns FW_QUEUE, 38 * silently drop skb instead of failing with -EPERM. 39 * Detlev Wengorz : Copy protocol for fragments. 40 * Hirokazu Takahashi: HW checksumming for outgoing UDP 41 * datagrams. 42 * Hirokazu Takahashi: sendfile() on UDP works now. 43 */ 44 45#include <asm/uaccess.h> 46#include <linux/module.h> 47#include <linux/types.h> 48#include <linux/kernel.h> 49#include <linux/mm.h> 50#include <linux/string.h> 51#include <linux/errno.h> 52#include <linux/highmem.h> 53#include <linux/slab.h> 54 55#include <linux/socket.h> 56#include <linux/sockios.h> 57#include <linux/in.h> 58#include <linux/inet.h> 59#include <linux/netdevice.h> 60#include <linux/etherdevice.h> 61#include <linux/proc_fs.h> 62#include <linux/stat.h> 63#include <linux/init.h> 64 65#include <net/snmp.h> 66#include <net/ip.h> 67#include <net/protocol.h> 68#include <net/route.h> 69#include <net/xfrm.h> 70#include <linux/skbuff.h> 71#include <net/sock.h> 72#include <net/arp.h> 73#include <net/icmp.h> 74#include <net/checksum.h> 75#include <net/inetpeer.h> 76#include <linux/igmp.h> 77#include <linux/netfilter_ipv4.h> 78#include <linux/netfilter_bridge.h> 79#include <linux/mroute.h> 80#include <linux/netlink.h> 81#include <linux/tcp.h> 82 83int sysctl_ip_default_ttl __read_mostly = IPDEFTTL; 84EXPORT_SYMBOL(sysctl_ip_default_ttl); 85 86/* Generate a checksum for an outgoing IP datagram. */ 87void ip_send_check(struct iphdr *iph) 88{ 89 iph->check = 0; 90 iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl); 91} 92EXPORT_SYMBOL(ip_send_check); 93 94int __ip_local_out_sk(struct sock *sk, 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, sk, skb, NULL, 101 skb_dst(skb)->dev, dst_output_sk); 102} 103 104int __ip_local_out(struct sk_buff *skb) 105{ 106 return __ip_local_out_sk(skb->sk, skb); 107} 108 109int ip_local_out_sk(struct sock *sk, struct sk_buff *skb) 110{ 111 int err; 112 113 err = __ip_local_out(skb); 114 if (likely(err == 1)) 115 err = dst_output_sk(sk, skb); 116 117 return err; 118} 119EXPORT_SYMBOL_GPL(ip_local_out_sk); 120 121static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst) 122{ 123 int ttl = inet->uc_ttl; 124 125 if (ttl < 0) 126 ttl = ip4_dst_hoplimit(dst); 127 return ttl; 128} 129 130/* 131 * Add an ip header to a skbuff and send it out. 132 * 133 */ 134int ip_build_and_send_pkt(struct sk_buff *skb, struct sock *sk, 135 __be32 saddr, __be32 daddr, struct ip_options_rcu *opt) 136{ 137 struct inet_sock *inet = inet_sk(sk); 138 struct rtable *rt = skb_rtable(skb); 139 struct iphdr *iph; 140 141 /* Build the IP header. */ 142 skb_push(skb, sizeof(struct iphdr) + (opt ? opt->opt.optlen : 0)); 143 skb_reset_network_header(skb); 144 iph = ip_hdr(skb); 145 iph->version = 4; 146 iph->ihl = 5; 147 iph->tos = inet->tos; 148 if (ip_dont_fragment(sk, &rt->dst)) 149 iph->frag_off = htons(IP_DF); 150 else 151 iph->frag_off = 0; 152 iph->ttl = ip_select_ttl(inet, &rt->dst); 153 iph->daddr = (opt && opt->opt.srr ? opt->opt.faddr : daddr); 154 iph->saddr = saddr; 155 iph->protocol = sk->sk_protocol; 156 ip_select_ident(sock_net(sk), skb, sk); 157 158 if (opt && opt->opt.optlen) { 159 iph->ihl += opt->opt.optlen>>2; 160 ip_options_build(skb, &opt->opt, daddr, rt, 0); 161 } 162 163 skb->priority = sk->sk_priority; 164 skb->mark = sk->sk_mark; 165 166 /* Send it out. */ 167 return ip_local_out(skb); 168} 169EXPORT_SYMBOL_GPL(ip_build_and_send_pkt); 170 171static inline int ip_finish_output2(struct sock *sk, struct sk_buff *skb) 172{ 173 struct dst_entry *dst = skb_dst(skb); 174 struct rtable *rt = (struct rtable *)dst; 175 struct net_device *dev = dst->dev; 176 unsigned int hh_len = LL_RESERVED_SPACE(dev); 177 struct neighbour *neigh; 178 u32 nexthop; 179 180 if (rt->rt_type == RTN_MULTICAST) { 181 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUTMCAST, skb->len); 182 } else if (rt->rt_type == RTN_BROADCAST) 183 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUTBCAST, skb->len); 184 185 /* Be paranoid, rather than too clever. */ 186 if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) { 187 struct sk_buff *skb2; 188 189 skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev)); 190 if (!skb2) { 191 kfree_skb(skb); 192 return -ENOMEM; 193 } 194 if (skb->sk) 195 skb_set_owner_w(skb2, skb->sk); 196 consume_skb(skb); 197 skb = skb2; 198 } 199 200 rcu_read_lock_bh(); 201 nexthop = (__force u32) rt_nexthop(rt, ip_hdr(skb)->daddr); 202 neigh = __ipv4_neigh_lookup_noref(dev, nexthop); 203 if (unlikely(!neigh)) 204 neigh = __neigh_create(&arp_tbl, &nexthop, dev, false); 205 if (!IS_ERR(neigh)) { 206 int res = dst_neigh_output(dst, neigh, skb); 207 208 rcu_read_unlock_bh(); 209 return res; 210 } 211 rcu_read_unlock_bh(); 212 213 net_dbg_ratelimited("%s: No header cache and no neighbour!\n", 214 __func__); 215 kfree_skb(skb); 216 return -EINVAL; 217} 218 219static int ip_finish_output_gso(struct sock *sk, struct sk_buff *skb) 220{ 221 netdev_features_t features; 222 struct sk_buff *segs; 223 int ret = 0; 224 225 /* common case: locally created skb or seglen is <= mtu */ 226 if (((IPCB(skb)->flags & IPSKB_FORWARDED) == 0) || 227 skb_gso_network_seglen(skb) <= ip_skb_dst_mtu(skb)) 228 return ip_finish_output2(sk, skb); 229 230 /* Slowpath - GSO segment length is exceeding the dst MTU. 231 * 232 * This can happen in two cases: 233 * 1) TCP GRO packet, DF bit not set 234 * 2) skb arrived via virtio-net, we thus get TSO/GSO skbs directly 235 * from host network stack. 236 */ 237 features = netif_skb_features(skb); 238 BUILD_BUG_ON(sizeof(*IPCB(skb)) > SKB_SGO_CB_OFFSET); 239 segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK); 240 if (IS_ERR_OR_NULL(segs)) { 241 kfree_skb(skb); 242 return -ENOMEM; 243 } 244 245 consume_skb(skb); 246 247 do { 248 struct sk_buff *nskb = segs->next; 249 int err; 250 251 segs->next = NULL; 252 err = ip_fragment(sk, segs, ip_finish_output2); 253 254 if (err && ret == 0) 255 ret = err; 256 segs = nskb; 257 } while (segs); 258 259 return ret; 260} 261 262static int ip_finish_output(struct sock *sk, struct sk_buff *skb) 263{ 264#if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM) 265 /* Policy lookup after SNAT yielded a new policy */ 266 if (skb_dst(skb)->xfrm) { 267 IPCB(skb)->flags |= IPSKB_REROUTED; 268 return dst_output_sk(sk, skb); 269 } 270#endif 271 if (skb_is_gso(skb)) 272 return ip_finish_output_gso(sk, skb); 273 274 if (skb->len > ip_skb_dst_mtu(skb)) 275 return ip_fragment(sk, skb, ip_finish_output2); 276 277 return ip_finish_output2(sk, skb); 278} 279 280int ip_mc_output(struct sock *sk, struct sk_buff *skb) 281{ 282 struct rtable *rt = skb_rtable(skb); 283 struct net_device *dev = rt->dst.dev; 284 285 /* 286 * If the indicated interface is up and running, send the packet. 287 */ 288 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len); 289 290 skb->dev = dev; 291 skb->protocol = htons(ETH_P_IP); 292 293 /* 294 * Multicasts are looped back for other local users 295 */ 296 297 if (rt->rt_flags&RTCF_MULTICAST) { 298 if (sk_mc_loop(sk) 299#ifdef CONFIG_IP_MROUTE 300 /* Small optimization: do not loopback not local frames, 301 which returned after forwarding; they will be dropped 302 by ip_mr_input in any case. 303 Note, that local frames are looped back to be delivered 304 to local recipients. 305 306 This check is duplicated in ip_mr_input at the moment. 307 */ 308 && 309 ((rt->rt_flags & RTCF_LOCAL) || 310 !(IPCB(skb)->flags & IPSKB_FORWARDED)) 311#endif 312 ) { 313 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC); 314 if (newskb) 315 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, 316 sk, newskb, NULL, newskb->dev, 317 dev_loopback_xmit); 318 } 319 320 /* Multicasts with ttl 0 must not go beyond the host */ 321 322 if (ip_hdr(skb)->ttl == 0) { 323 kfree_skb(skb); 324 return 0; 325 } 326 } 327 328 if (rt->rt_flags&RTCF_BROADCAST) { 329 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC); 330 if (newskb) 331 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, sk, newskb, 332 NULL, newskb->dev, dev_loopback_xmit); 333 } 334 335 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, sk, skb, NULL, 336 skb->dev, ip_finish_output, 337 !(IPCB(skb)->flags & IPSKB_REROUTED)); 338} 339 340int ip_output(struct sock *sk, struct sk_buff *skb) 341{ 342 struct net_device *dev = skb_dst(skb)->dev; 343 344 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len); 345 346 skb->dev = dev; 347 skb->protocol = htons(ETH_P_IP); 348 349 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, sk, skb, 350 NULL, dev, 351 ip_finish_output, 352 !(IPCB(skb)->flags & IPSKB_REROUTED)); 353} 354 355/* 356 * copy saddr and daddr, possibly using 64bit load/stores 357 * Equivalent to : 358 * iph->saddr = fl4->saddr; 359 * iph->daddr = fl4->daddr; 360 */ 361static void ip_copy_addrs(struct iphdr *iph, const struct flowi4 *fl4) 362{ 363 BUILD_BUG_ON(offsetof(typeof(*fl4), daddr) != 364 offsetof(typeof(*fl4), saddr) + sizeof(fl4->saddr)); 365 memcpy(&iph->saddr, &fl4->saddr, 366 sizeof(fl4->saddr) + sizeof(fl4->daddr)); 367} 368 369/* Note: skb->sk can be different from sk, in case of tunnels */ 370int ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl) 371{ 372 struct inet_sock *inet = inet_sk(sk); 373 struct ip_options_rcu *inet_opt; 374 struct flowi4 *fl4; 375 struct rtable *rt; 376 struct iphdr *iph; 377 int res; 378 379 /* Skip all of this if the packet is already routed, 380 * f.e. by something like SCTP. 381 */ 382 rcu_read_lock(); 383 inet_opt = rcu_dereference(inet->inet_opt); 384 fl4 = &fl->u.ip4; 385 rt = skb_rtable(skb); 386 if (rt) 387 goto packet_routed; 388 389 /* Make sure we can route this packet. */ 390 rt = (struct rtable *)__sk_dst_check(sk, 0); 391 if (!rt) { 392 __be32 daddr; 393 394 /* Use correct destination address if we have options. */ 395 daddr = inet->inet_daddr; 396 if (inet_opt && inet_opt->opt.srr) 397 daddr = inet_opt->opt.faddr; 398 399 /* If this fails, retransmit mechanism of transport layer will 400 * keep trying until route appears or the connection times 401 * itself out. 402 */ 403 rt = ip_route_output_ports(sock_net(sk), fl4, sk, 404 daddr, inet->inet_saddr, 405 inet->inet_dport, 406 inet->inet_sport, 407 sk->sk_protocol, 408 RT_CONN_FLAGS(sk), 409 sk->sk_bound_dev_if); 410 if (IS_ERR(rt)) 411 goto no_route; 412 sk_setup_caps(sk, &rt->dst); 413 } 414 skb_dst_set_noref(skb, &rt->dst); 415 416packet_routed: 417 if (inet_opt && inet_opt->opt.is_strictroute && rt->rt_uses_gateway) 418 goto no_route; 419 420 /* OK, we know where to send it, allocate and build IP header. */ 421 skb_push(skb, sizeof(struct iphdr) + (inet_opt ? inet_opt->opt.optlen : 0)); 422 skb_reset_network_header(skb); 423 iph = ip_hdr(skb); 424 *((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (inet->tos & 0xff)); 425 if (ip_dont_fragment(sk, &rt->dst) && !skb->ignore_df) 426 iph->frag_off = htons(IP_DF); 427 else 428 iph->frag_off = 0; 429 iph->ttl = ip_select_ttl(inet, &rt->dst); 430 iph->protocol = sk->sk_protocol; 431 ip_copy_addrs(iph, fl4); 432 433 /* Transport layer set skb->h.foo itself. */ 434 435 if (inet_opt && inet_opt->opt.optlen) { 436 iph->ihl += inet_opt->opt.optlen >> 2; 437 ip_options_build(skb, &inet_opt->opt, inet->inet_daddr, rt, 0); 438 } 439 440 ip_select_ident_segs(sock_net(sk), skb, sk, 441 skb_shinfo(skb)->gso_segs ?: 1); 442 443 /* TODO : should we use skb->sk here instead of sk ? */ 444 skb->priority = sk->sk_priority; 445 skb->mark = sk->sk_mark; 446 447 res = ip_local_out(skb); 448 rcu_read_unlock(); 449 return res; 450 451no_route: 452 rcu_read_unlock(); 453 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES); 454 kfree_skb(skb); 455 return -EHOSTUNREACH; 456} 457EXPORT_SYMBOL(ip_queue_xmit); 458 459static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from) 460{ 461 to->pkt_type = from->pkt_type; 462 to->priority = from->priority; 463 to->protocol = from->protocol; 464 skb_dst_drop(to); 465 skb_dst_copy(to, from); 466 to->dev = from->dev; 467 to->mark = from->mark; 468 469 /* Copy the flags to each fragment. */ 470 IPCB(to)->flags = IPCB(from)->flags; 471 472#ifdef CONFIG_NET_SCHED 473 to->tc_index = from->tc_index; 474#endif 475 nf_copy(to, from); 476#if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE) 477 to->ipvs_property = from->ipvs_property; 478#endif 479 skb_copy_secmark(to, from); 480} 481 482/* 483 * This IP datagram is too large to be sent in one piece. Break it up into 484 * smaller pieces (each of size equal to IP header plus 485 * a block of the data of the original IP data part) that will yet fit in a 486 * single device frame, and queue such a frame for sending. 487 */ 488 489int ip_fragment(struct sock *sk, struct sk_buff *skb, 490 int (*output)(struct sock *, struct sk_buff *)) 491{ 492 struct iphdr *iph; 493 int ptr; 494 struct net_device *dev; 495 struct sk_buff *skb2; 496 unsigned int mtu, hlen, left, len, ll_rs; 497 int offset; 498 __be16 not_last_frag; 499 struct rtable *rt = skb_rtable(skb); 500 int err = 0; 501 502 dev = rt->dst.dev; 503 504 /* 505 * Point into the IP datagram header. 506 */ 507 508 iph = ip_hdr(skb); 509 510 mtu = ip_skb_dst_mtu(skb); 511 if (unlikely(((iph->frag_off & htons(IP_DF)) && !skb->ignore_df) || 512 (IPCB(skb)->frag_max_size && 513 IPCB(skb)->frag_max_size > mtu))) { 514 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); 515 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, 516 htonl(mtu)); 517 kfree_skb(skb); 518 return -EMSGSIZE; 519 } 520 521 /* 522 * Setup starting values. 523 */ 524 525 hlen = iph->ihl * 4; 526 mtu = mtu - hlen; /* Size of data space */ 527#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) 528 if (skb->nf_bridge) 529 mtu -= nf_bridge_mtu_reduction(skb); 530#endif 531 IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE; 532 533 /* When frag_list is given, use it. First, check its validity: 534 * some transformers could create wrong frag_list or break existing 535 * one, it is not prohibited. In this case fall back to copying. 536 * 537 * LATER: this step can be merged to real generation of fragments, 538 * we can switch to copy when see the first bad fragment. 539 */ 540 if (skb_has_frag_list(skb)) { 541 struct sk_buff *frag, *frag2; 542 int first_len = skb_pagelen(skb); 543 544 if (first_len - hlen > mtu || 545 ((first_len - hlen) & 7) || 546 ip_is_fragment(iph) || 547 skb_cloned(skb)) 548 goto slow_path; 549 550 skb_walk_frags(skb, frag) { 551 /* Correct geometry. */ 552 if (frag->len > mtu || 553 ((frag->len & 7) && frag->next) || 554 skb_headroom(frag) < hlen) 555 goto slow_path_clean; 556 557 /* Partially cloned skb? */ 558 if (skb_shared(frag)) 559 goto slow_path_clean; 560 561 BUG_ON(frag->sk); 562 if (skb->sk) { 563 frag->sk = skb->sk; 564 frag->destructor = sock_wfree; 565 } 566 skb->truesize -= frag->truesize; 567 } 568 569 /* Everything is OK. Generate! */ 570 571 err = 0; 572 offset = 0; 573 frag = skb_shinfo(skb)->frag_list; 574 skb_frag_list_init(skb); 575 skb->data_len = first_len - skb_headlen(skb); 576 skb->len = first_len; 577 iph->tot_len = htons(first_len); 578 iph->frag_off = htons(IP_MF); 579 ip_send_check(iph); 580 581 for (;;) { 582 /* Prepare header of the next frame, 583 * before previous one went down. */ 584 if (frag) { 585 frag->ip_summed = CHECKSUM_NONE; 586 skb_reset_transport_header(frag); 587 __skb_push(frag, hlen); 588 skb_reset_network_header(frag); 589 memcpy(skb_network_header(frag), iph, hlen); 590 iph = ip_hdr(frag); 591 iph->tot_len = htons(frag->len); 592 ip_copy_metadata(frag, skb); 593 if (offset == 0) 594 ip_options_fragment(frag); 595 offset += skb->len - hlen; 596 iph->frag_off = htons(offset>>3); 597 if (frag->next) 598 iph->frag_off |= htons(IP_MF); 599 /* Ready, complete checksum */ 600 ip_send_check(iph); 601 } 602 603 err = output(sk, skb); 604 605 if (!err) 606 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES); 607 if (err || !frag) 608 break; 609 610 skb = frag; 611 frag = skb->next; 612 skb->next = NULL; 613 } 614 615 if (err == 0) { 616 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS); 617 return 0; 618 } 619 620 while (frag) { 621 skb = frag->next; 622 kfree_skb(frag); 623 frag = skb; 624 } 625 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); 626 return err; 627 628slow_path_clean: 629 skb_walk_frags(skb, frag2) { 630 if (frag2 == frag) 631 break; 632 frag2->sk = NULL; 633 frag2->destructor = NULL; 634 skb->truesize += frag2->truesize; 635 } 636 } 637 638slow_path: 639 /* for offloaded checksums cleanup checksum before fragmentation */ 640 if ((skb->ip_summed == CHECKSUM_PARTIAL) && skb_checksum_help(skb)) 641 goto fail; 642 iph = ip_hdr(skb); 643 644 left = skb->len - hlen; /* Space per frame */ 645 ptr = hlen; /* Where to start from */ 646 647 ll_rs = LL_RESERVED_SPACE(rt->dst.dev); 648 649 /* 650 * Fragment the datagram. 651 */ 652 653 offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3; 654 not_last_frag = iph->frag_off & htons(IP_MF); 655 656 /* 657 * Keep copying data until we run out. 658 */ 659 660 while (left > 0) { 661 len = left; 662 /* IF: it doesn't fit, use 'mtu' - the data space left */ 663 if (len > mtu) 664 len = mtu; 665 /* IF: we are not sending up to and including the packet end 666 then align the next start on an eight byte boundary */ 667 if (len < left) { 668 len &= ~7; 669 } 670 671 /* Allocate buffer */ 672 skb2 = alloc_skb(len + hlen + ll_rs, GFP_ATOMIC); 673 if (!skb2) { 674 err = -ENOMEM; 675 goto fail; 676 } 677 678 /* 679 * Set up data on packet 680 */ 681 682 ip_copy_metadata(skb2, skb); 683 skb_reserve(skb2, ll_rs); 684 skb_put(skb2, len + hlen); 685 skb_reset_network_header(skb2); 686 skb2->transport_header = skb2->network_header + hlen; 687 688 /* 689 * Charge the memory for the fragment to any owner 690 * it might possess 691 */ 692 693 if (skb->sk) 694 skb_set_owner_w(skb2, skb->sk); 695 696 /* 697 * Copy the packet header into the new buffer. 698 */ 699 700 skb_copy_from_linear_data(skb, skb_network_header(skb2), hlen); 701 702 /* 703 * Copy a block of the IP datagram. 704 */ 705 if (skb_copy_bits(skb, ptr, skb_transport_header(skb2), len)) 706 BUG(); 707 left -= len; 708 709 /* 710 * Fill in the new header fields. 711 */ 712 iph = ip_hdr(skb2); 713 iph->frag_off = htons((offset >> 3)); 714 715 /* ANK: dirty, but effective trick. Upgrade options only if 716 * the segment to be fragmented was THE FIRST (otherwise, 717 * options are already fixed) and make it ONCE 718 * on the initial skb, so that all the following fragments 719 * will inherit fixed options. 720 */ 721 if (offset == 0) 722 ip_options_fragment(skb); 723 724 /* 725 * Added AC : If we are fragmenting a fragment that's not the 726 * last fragment then keep MF on each bit 727 */ 728 if (left > 0 || not_last_frag) 729 iph->frag_off |= htons(IP_MF); 730 ptr += len; 731 offset += len; 732 733 /* 734 * Put this fragment into the sending queue. 735 */ 736 iph->tot_len = htons(len + hlen); 737 738 ip_send_check(iph); 739 740 err = output(sk, skb2); 741 if (err) 742 goto fail; 743 744 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES); 745 } 746 consume_skb(skb); 747 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS); 748 return err; 749 750fail: 751 kfree_skb(skb); 752 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); 753 return err; 754} 755EXPORT_SYMBOL(ip_fragment); 756 757int 758ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb) 759{ 760 struct msghdr *msg = from; 761 762 if (skb->ip_summed == CHECKSUM_PARTIAL) { 763 if (copy_from_iter(to, len, &msg->msg_iter) != len) 764 return -EFAULT; 765 } else { 766 __wsum csum = 0; 767 if (csum_and_copy_from_iter(to, len, &csum, &msg->msg_iter) != len) 768 return -EFAULT; 769 skb->csum = csum_block_add(skb->csum, csum, odd); 770 } 771 return 0; 772} 773EXPORT_SYMBOL(ip_generic_getfrag); 774 775static inline __wsum 776csum_page(struct page *page, int offset, int copy) 777{ 778 char *kaddr; 779 __wsum csum; 780 kaddr = kmap(page); 781 csum = csum_partial(kaddr + offset, copy, 0); 782 kunmap(page); 783 return csum; 784} 785 786static inline int ip_ufo_append_data(struct sock *sk, 787 struct sk_buff_head *queue, 788 int getfrag(void *from, char *to, int offset, int len, 789 int odd, struct sk_buff *skb), 790 void *from, int length, int hh_len, int fragheaderlen, 791 int transhdrlen, int maxfraglen, unsigned int flags) 792{ 793 struct sk_buff *skb; 794 int err; 795 796 /* There is support for UDP fragmentation offload by network 797 * device, so create one single skb packet containing complete 798 * udp datagram 799 */ 800 skb = skb_peek_tail(queue); 801 if (!skb) { 802 skb = sock_alloc_send_skb(sk, 803 hh_len + fragheaderlen + transhdrlen + 20, 804 (flags & MSG_DONTWAIT), &err); 805 806 if (!skb) 807 return err; 808 809 /* reserve space for Hardware header */ 810 skb_reserve(skb, hh_len); 811 812 /* create space for UDP/IP header */ 813 skb_put(skb, fragheaderlen + transhdrlen); 814 815 /* initialize network header pointer */ 816 skb_reset_network_header(skb); 817 818 /* initialize protocol header pointer */ 819 skb->transport_header = skb->network_header + fragheaderlen; 820 821 skb->csum = 0; 822 823 __skb_queue_tail(queue, skb); 824 } else if (skb_is_gso(skb)) { 825 goto append; 826 } 827 828 skb->ip_summed = CHECKSUM_PARTIAL; 829 /* specify the length of each IP datagram fragment */ 830 skb_shinfo(skb)->gso_size = maxfraglen - fragheaderlen; 831 skb_shinfo(skb)->gso_type = SKB_GSO_UDP; 832 833append: 834 return skb_append_datato_frags(sk, skb, getfrag, from, 835 (length - transhdrlen)); 836} 837 838static int __ip_append_data(struct sock *sk, 839 struct flowi4 *fl4, 840 struct sk_buff_head *queue, 841 struct inet_cork *cork, 842 struct page_frag *pfrag, 843 int getfrag(void *from, char *to, int offset, 844 int len, int odd, struct sk_buff *skb), 845 void *from, int length, int transhdrlen, 846 unsigned int flags) 847{ 848 struct inet_sock *inet = inet_sk(sk); 849 struct sk_buff *skb; 850 851 struct ip_options *opt = cork->opt; 852 int hh_len; 853 int exthdrlen; 854 int mtu; 855 int copy; 856 int err; 857 int offset = 0; 858 unsigned int maxfraglen, fragheaderlen, maxnonfragsize; 859 int csummode = CHECKSUM_NONE; 860 struct rtable *rt = (struct rtable *)cork->dst; 861 u32 tskey = 0; 862 863 skb = skb_peek_tail(queue); 864 865 exthdrlen = !skb ? rt->dst.header_len : 0; 866 mtu = cork->fragsize; 867 if (cork->tx_flags & SKBTX_ANY_SW_TSTAMP && 868 sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID) 869 tskey = sk->sk_tskey++; 870 871 hh_len = LL_RESERVED_SPACE(rt->dst.dev); 872 873 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0); 874 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen; 875 maxnonfragsize = ip_sk_ignore_df(sk) ? 0xFFFF : mtu; 876 877 if (cork->length + length > maxnonfragsize - fragheaderlen) { 878 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport, 879 mtu - (opt ? opt->optlen : 0)); 880 return -EMSGSIZE; 881 } 882 883 /* 884 * transhdrlen > 0 means that this is the first fragment and we wish 885 * it won't be fragmented in the future. 886 */ 887 if (transhdrlen && 888 length + fragheaderlen <= mtu && 889 rt->dst.dev->features & NETIF_F_V4_CSUM && 890 !exthdrlen) 891 csummode = CHECKSUM_PARTIAL; 892 893 cork->length += length; 894 if (((length > mtu) || (skb && skb_is_gso(skb))) && 895 (sk->sk_protocol == IPPROTO_UDP) && 896 (rt->dst.dev->features & NETIF_F_UFO) && !rt->dst.header_len && 897 (sk->sk_type == SOCK_DGRAM) && !sk->sk_no_check_tx) { 898 err = ip_ufo_append_data(sk, queue, getfrag, from, length, 899 hh_len, fragheaderlen, transhdrlen, 900 maxfraglen, flags); 901 if (err) 902 goto error; 903 return 0; 904 } 905 906 /* So, what's going on in the loop below? 907 * 908 * We use calculated fragment length to generate chained skb, 909 * each of segments is IP fragment ready for sending to network after 910 * adding appropriate IP header. 911 */ 912 913 if (!skb) 914 goto alloc_new_skb; 915 916 while (length > 0) { 917 /* Check if the remaining data fits into current packet. */ 918 copy = mtu - skb->len; 919 if (copy < length) 920 copy = maxfraglen - skb->len; 921 if (copy <= 0) { 922 char *data; 923 unsigned int datalen; 924 unsigned int fraglen; 925 unsigned int fraggap; 926 unsigned int alloclen; 927 struct sk_buff *skb_prev; 928alloc_new_skb: 929 skb_prev = skb; 930 if (skb_prev) 931 fraggap = skb_prev->len - maxfraglen; 932 else 933 fraggap = 0; 934 935 /* 936 * If remaining data exceeds the mtu, 937 * we know we need more fragment(s). 938 */ 939 datalen = length + fraggap; 940 if (datalen > mtu - fragheaderlen) 941 datalen = maxfraglen - fragheaderlen; 942 fraglen = datalen + fragheaderlen; 943 944 if ((flags & MSG_MORE) && 945 !(rt->dst.dev->features&NETIF_F_SG)) 946 alloclen = mtu; 947 else 948 alloclen = fraglen; 949 950 alloclen += exthdrlen; 951 952 /* The last fragment gets additional space at tail. 953 * Note, with MSG_MORE we overallocate on fragments, 954 * because we have no idea what fragment will be 955 * the last. 956 */ 957 if (datalen == length + fraggap) 958 alloclen += rt->dst.trailer_len; 959 960 if (transhdrlen) { 961 skb = sock_alloc_send_skb(sk, 962 alloclen + hh_len + 15, 963 (flags & MSG_DONTWAIT), &err); 964 } else { 965 skb = NULL; 966 if (atomic_read(&sk->sk_wmem_alloc) <= 967 2 * sk->sk_sndbuf) 968 skb = sock_wmalloc(sk, 969 alloclen + hh_len + 15, 1, 970 sk->sk_allocation); 971 if (unlikely(!skb)) 972 err = -ENOBUFS; 973 } 974 if (!skb) 975 goto error; 976 977 /* 978 * Fill in the control structures 979 */ 980 skb->ip_summed = csummode; 981 skb->csum = 0; 982 skb_reserve(skb, hh_len); 983 984 /* only the initial fragment is time stamped */ 985 skb_shinfo(skb)->tx_flags = cork->tx_flags; 986 cork->tx_flags = 0; 987 skb_shinfo(skb)->tskey = tskey; 988 tskey = 0; 989 990 /* 991 * Find where to start putting bytes. 992 */ 993 data = skb_put(skb, fraglen + exthdrlen); 994 skb_set_network_header(skb, exthdrlen); 995 skb->transport_header = (skb->network_header + 996 fragheaderlen); 997 data += fragheaderlen + exthdrlen; 998 999 if (fraggap) { 1000 skb->csum = skb_copy_and_csum_bits( 1001 skb_prev, maxfraglen, 1002 data + transhdrlen, fraggap, 0); 1003 skb_prev->csum = csum_sub(skb_prev->csum, 1004 skb->csum); 1005 data += fraggap; 1006 pskb_trim_unique(skb_prev, maxfraglen); 1007 } 1008 1009 copy = datalen - transhdrlen - fraggap; 1010 if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) { 1011 err = -EFAULT; 1012 kfree_skb(skb); 1013 goto error; 1014 } 1015 1016 offset += copy; 1017 length -= datalen - fraggap; 1018 transhdrlen = 0; 1019 exthdrlen = 0; 1020 csummode = CHECKSUM_NONE; 1021 1022 /* 1023 * Put the packet on the pending queue. 1024 */ 1025 __skb_queue_tail(queue, skb); 1026 continue; 1027 } 1028 1029 if (copy > length) 1030 copy = length; 1031 1032 if (!(rt->dst.dev->features&NETIF_F_SG)) { 1033 unsigned int off; 1034 1035 off = skb->len; 1036 if (getfrag(from, skb_put(skb, copy), 1037 offset, copy, off, skb) < 0) { 1038 __skb_trim(skb, off); 1039 err = -EFAULT; 1040 goto error; 1041 } 1042 } else { 1043 int i = skb_shinfo(skb)->nr_frags; 1044 1045 err = -ENOMEM; 1046 if (!sk_page_frag_refill(sk, pfrag)) 1047 goto error; 1048 1049 if (!skb_can_coalesce(skb, i, pfrag->page, 1050 pfrag->offset)) { 1051 err = -EMSGSIZE; 1052 if (i == MAX_SKB_FRAGS) 1053 goto error; 1054 1055 __skb_fill_page_desc(skb, i, pfrag->page, 1056 pfrag->offset, 0); 1057 skb_shinfo(skb)->nr_frags = ++i; 1058 get_page(pfrag->page); 1059 } 1060 copy = min_t(int, copy, pfrag->size - pfrag->offset); 1061 if (getfrag(from, 1062 page_address(pfrag->page) + pfrag->offset, 1063 offset, copy, skb->len, skb) < 0) 1064 goto error_efault; 1065 1066 pfrag->offset += copy; 1067 skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy); 1068 skb->len += copy; 1069 skb->data_len += copy; 1070 skb->truesize += copy; 1071 atomic_add(copy, &sk->sk_wmem_alloc); 1072 } 1073 offset += copy; 1074 length -= copy; 1075 } 1076 1077 return 0; 1078 1079error_efault: 1080 err = -EFAULT; 1081error: 1082 cork->length -= length; 1083 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS); 1084 return err; 1085} 1086 1087static int ip_setup_cork(struct sock *sk, struct inet_cork *cork, 1088 struct ipcm_cookie *ipc, struct rtable **rtp) 1089{ 1090 struct ip_options_rcu *opt; 1091 struct rtable *rt; 1092 1093 /* 1094 * setup for corking. 1095 */ 1096 opt = ipc->opt; 1097 if (opt) { 1098 if (!cork->opt) { 1099 cork->opt = kmalloc(sizeof(struct ip_options) + 40, 1100 sk->sk_allocation); 1101 if (unlikely(!cork->opt)) 1102 return -ENOBUFS; 1103 } 1104 memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen); 1105 cork->flags |= IPCORK_OPT; 1106 cork->addr = ipc->addr; 1107 } 1108 rt = *rtp; 1109 if (unlikely(!rt)) 1110 return -EFAULT; 1111 /* 1112 * We steal reference to this route, caller should not release it 1113 */ 1114 *rtp = NULL; 1115 cork->fragsize = ip_sk_use_pmtu(sk) ? 1116 dst_mtu(&rt->dst) : rt->dst.dev->mtu; 1117 cork->dst = &rt->dst; 1118 cork->length = 0; 1119 cork->ttl = ipc->ttl; 1120 cork->tos = ipc->tos; 1121 cork->priority = ipc->priority; 1122 cork->tx_flags = ipc->tx_flags; 1123 1124 return 0; 1125} 1126 1127/* 1128 * ip_append_data() and ip_append_page() can make one large IP datagram 1129 * from many pieces of data. Each pieces will be holded on the socket 1130 * until ip_push_pending_frames() is called. Each piece can be a page 1131 * or non-page data. 1132 * 1133 * Not only UDP, other transport protocols - e.g. raw sockets - can use 1134 * this interface potentially. 1135 * 1136 * LATER: length must be adjusted by pad at tail, when it is required. 1137 */ 1138int ip_append_data(struct sock *sk, struct flowi4 *fl4, 1139 int getfrag(void *from, char *to, int offset, int len, 1140 int odd, struct sk_buff *skb), 1141 void *from, int length, int transhdrlen, 1142 struct ipcm_cookie *ipc, struct rtable **rtp, 1143 unsigned int flags) 1144{ 1145 struct inet_sock *inet = inet_sk(sk); 1146 int err; 1147 1148 if (flags&MSG_PROBE) 1149 return 0; 1150 1151 if (skb_queue_empty(&sk->sk_write_queue)) { 1152 err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp); 1153 if (err) 1154 return err; 1155 } else { 1156 transhdrlen = 0; 1157 } 1158 1159 return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base, 1160 sk_page_frag(sk), getfrag, 1161 from, length, transhdrlen, flags); 1162} 1163 1164ssize_t ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page, 1165 int offset, size_t size, int flags) 1166{ 1167 struct inet_sock *inet = inet_sk(sk); 1168 struct sk_buff *skb; 1169 struct rtable *rt; 1170 struct ip_options *opt = NULL; 1171 struct inet_cork *cork; 1172 int hh_len; 1173 int mtu; 1174 int len; 1175 int err; 1176 unsigned int maxfraglen, fragheaderlen, fraggap, maxnonfragsize; 1177 1178 if (inet->hdrincl) 1179 return -EPERM; 1180 1181 if (flags&MSG_PROBE) 1182 return 0; 1183 1184 if (skb_queue_empty(&sk->sk_write_queue)) 1185 return -EINVAL; 1186 1187 cork = &inet->cork.base; 1188 rt = (struct rtable *)cork->dst; 1189 if (cork->flags & IPCORK_OPT) 1190 opt = cork->opt; 1191 1192 if (!(rt->dst.dev->features&NETIF_F_SG)) 1193 return -EOPNOTSUPP; 1194 1195 hh_len = LL_RESERVED_SPACE(rt->dst.dev); 1196 mtu = cork->fragsize; 1197 1198 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0); 1199 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen; 1200 maxnonfragsize = ip_sk_ignore_df(sk) ? 0xFFFF : mtu; 1201 1202 if (cork->length + size > maxnonfragsize - fragheaderlen) { 1203 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport, 1204 mtu - (opt ? opt->optlen : 0)); 1205 return -EMSGSIZE; 1206 } 1207 1208 skb = skb_peek_tail(&sk->sk_write_queue); 1209 if (!skb) 1210 return -EINVAL; 1211 1212 cork->length += size; 1213 if ((size + skb->len > mtu) && 1214 (sk->sk_protocol == IPPROTO_UDP) && 1215 (rt->dst.dev->features & NETIF_F_UFO)) { 1216 skb_shinfo(skb)->gso_size = mtu - fragheaderlen; 1217 skb_shinfo(skb)->gso_type = SKB_GSO_UDP; 1218 } 1219 1220 while (size > 0) { 1221 int i; 1222 1223 if (skb_is_gso(skb)) 1224 len = size; 1225 else { 1226 1227 /* Check if the remaining data fits into current packet. */ 1228 len = mtu - skb->len; 1229 if (len < size) 1230 len = maxfraglen - skb->len; 1231 } 1232 if (len <= 0) { 1233 struct sk_buff *skb_prev; 1234 int alloclen; 1235 1236 skb_prev = skb; 1237 fraggap = skb_prev->len - maxfraglen; 1238 1239 alloclen = fragheaderlen + hh_len + fraggap + 15; 1240 skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation); 1241 if (unlikely(!skb)) { 1242 err = -ENOBUFS; 1243 goto error; 1244 } 1245 1246 /* 1247 * Fill in the control structures 1248 */ 1249 skb->ip_summed = CHECKSUM_NONE; 1250 skb->csum = 0; 1251 skb_reserve(skb, hh_len); 1252 1253 /* 1254 * Find where to start putting bytes. 1255 */ 1256 skb_put(skb, fragheaderlen + fraggap); 1257 skb_reset_network_header(skb); 1258 skb->transport_header = (skb->network_header + 1259 fragheaderlen); 1260 if (fraggap) { 1261 skb->csum = skb_copy_and_csum_bits(skb_prev, 1262 maxfraglen, 1263 skb_transport_header(skb), 1264 fraggap, 0); 1265 skb_prev->csum = csum_sub(skb_prev->csum, 1266 skb->csum); 1267 pskb_trim_unique(skb_prev, maxfraglen); 1268 } 1269 1270 /* 1271 * Put the packet on the pending queue. 1272 */ 1273 __skb_queue_tail(&sk->sk_write_queue, skb); 1274 continue; 1275 } 1276 1277 i = skb_shinfo(skb)->nr_frags; 1278 if (len > size) 1279 len = size; 1280 if (skb_can_coalesce(skb, i, page, offset)) { 1281 skb_frag_size_add(&skb_shinfo(skb)->frags[i-1], len); 1282 } else if (i < MAX_SKB_FRAGS) { 1283 get_page(page); 1284 skb_fill_page_desc(skb, i, page, offset, len); 1285 } else { 1286 err = -EMSGSIZE; 1287 goto error; 1288 } 1289 1290 if (skb->ip_summed == CHECKSUM_NONE) { 1291 __wsum csum; 1292 csum = csum_page(page, offset, len); 1293 skb->csum = csum_block_add(skb->csum, csum, skb->len); 1294 } 1295 1296 skb->len += len; 1297 skb->data_len += len; 1298 skb->truesize += len; 1299 atomic_add(len, &sk->sk_wmem_alloc); 1300 offset += len; 1301 size -= len; 1302 } 1303 return 0; 1304 1305error: 1306 cork->length -= size; 1307 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS); 1308 return err; 1309} 1310 1311static void ip_cork_release(struct inet_cork *cork) 1312{ 1313 cork->flags &= ~IPCORK_OPT; 1314 kfree(cork->opt); 1315 cork->opt = NULL; 1316 dst_release(cork->dst); 1317 cork->dst = NULL; 1318} 1319 1320/* 1321 * Combined all pending IP fragments on the socket as one IP datagram 1322 * and push them out. 1323 */ 1324struct sk_buff *__ip_make_skb(struct sock *sk, 1325 struct flowi4 *fl4, 1326 struct sk_buff_head *queue, 1327 struct inet_cork *cork) 1328{ 1329 struct sk_buff *skb, *tmp_skb; 1330 struct sk_buff **tail_skb; 1331 struct inet_sock *inet = inet_sk(sk); 1332 struct net *net = sock_net(sk); 1333 struct ip_options *opt = NULL; 1334 struct rtable *rt = (struct rtable *)cork->dst; 1335 struct iphdr *iph; 1336 __be16 df = 0; 1337 __u8 ttl; 1338 1339 skb = __skb_dequeue(queue); 1340 if (!skb) 1341 goto out; 1342 tail_skb = &(skb_shinfo(skb)->frag_list); 1343 1344 /* move skb->data to ip header from ext header */ 1345 if (skb->data < skb_network_header(skb)) 1346 __skb_pull(skb, skb_network_offset(skb)); 1347 while ((tmp_skb = __skb_dequeue(queue)) != NULL) { 1348 __skb_pull(tmp_skb, skb_network_header_len(skb)); 1349 *tail_skb = tmp_skb; 1350 tail_skb = &(tmp_skb->next); 1351 skb->len += tmp_skb->len; 1352 skb->data_len += tmp_skb->len; 1353 skb->truesize += tmp_skb->truesize; 1354 tmp_skb->destructor = NULL; 1355 tmp_skb->sk = NULL; 1356 } 1357 1358 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow 1359 * to fragment the frame generated here. No matter, what transforms 1360 * how transforms change size of the packet, it will come out. 1361 */ 1362 skb->ignore_df = ip_sk_ignore_df(sk); 1363 1364 /* DF bit is set when we want to see DF on outgoing frames. 1365 * If ignore_df is set too, we still allow to fragment this frame 1366 * locally. */ 1367 if (inet->pmtudisc == IP_PMTUDISC_DO || 1368 inet->pmtudisc == IP_PMTUDISC_PROBE || 1369 (skb->len <= dst_mtu(&rt->dst) && 1370 ip_dont_fragment(sk, &rt->dst))) 1371 df = htons(IP_DF); 1372 1373 if (cork->flags & IPCORK_OPT) 1374 opt = cork->opt; 1375 1376 if (cork->ttl != 0) 1377 ttl = cork->ttl; 1378 else if (rt->rt_type == RTN_MULTICAST) 1379 ttl = inet->mc_ttl; 1380 else 1381 ttl = ip_select_ttl(inet, &rt->dst); 1382 1383 iph = ip_hdr(skb); 1384 iph->version = 4; 1385 iph->ihl = 5; 1386 iph->tos = (cork->tos != -1) ? cork->tos : inet->tos; 1387 iph->frag_off = df; 1388 iph->ttl = ttl; 1389 iph->protocol = sk->sk_protocol; 1390 ip_copy_addrs(iph, fl4); 1391 ip_select_ident(net, skb, sk); 1392 1393 if (opt) { 1394 iph->ihl += opt->optlen>>2; 1395 ip_options_build(skb, opt, cork->addr, rt, 0); 1396 } 1397 1398 skb->priority = (cork->tos != -1) ? cork->priority: sk->sk_priority; 1399 skb->mark = sk->sk_mark; 1400 /* 1401 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec 1402 * on dst refcount 1403 */ 1404 cork->dst = NULL; 1405 skb_dst_set(skb, &rt->dst); 1406 1407 if (iph->protocol == IPPROTO_ICMP) 1408 icmp_out_count(net, ((struct icmphdr *) 1409 skb_transport_header(skb))->type); 1410 1411 ip_cork_release(cork); 1412out: 1413 return skb; 1414} 1415 1416int ip_send_skb(struct net *net, struct sk_buff *skb) 1417{ 1418 int err; 1419 1420 err = ip_local_out(skb); 1421 if (err) { 1422 if (err > 0) 1423 err = net_xmit_errno(err); 1424 if (err) 1425 IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS); 1426 } 1427 1428 return err; 1429} 1430 1431int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4) 1432{ 1433 struct sk_buff *skb; 1434 1435 skb = ip_finish_skb(sk, fl4); 1436 if (!skb) 1437 return 0; 1438 1439 /* Netfilter gets whole the not fragmented skb. */ 1440 return ip_send_skb(sock_net(sk), skb); 1441} 1442 1443/* 1444 * Throw away all pending data on the socket. 1445 */ 1446static void __ip_flush_pending_frames(struct sock *sk, 1447 struct sk_buff_head *queue, 1448 struct inet_cork *cork) 1449{ 1450 struct sk_buff *skb; 1451 1452 while ((skb = __skb_dequeue_tail(queue)) != NULL) 1453 kfree_skb(skb); 1454 1455 ip_cork_release(cork); 1456} 1457 1458void ip_flush_pending_frames(struct sock *sk) 1459{ 1460 __ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork.base); 1461} 1462 1463struct sk_buff *ip_make_skb(struct sock *sk, 1464 struct flowi4 *fl4, 1465 int getfrag(void *from, char *to, int offset, 1466 int len, int odd, struct sk_buff *skb), 1467 void *from, int length, int transhdrlen, 1468 struct ipcm_cookie *ipc, struct rtable **rtp, 1469 unsigned int flags) 1470{ 1471 struct inet_cork cork; 1472 struct sk_buff_head queue; 1473 int err; 1474 1475 if (flags & MSG_PROBE) 1476 return NULL; 1477 1478 __skb_queue_head_init(&queue); 1479 1480 cork.flags = 0; 1481 cork.addr = 0; 1482 cork.opt = NULL; 1483 err = ip_setup_cork(sk, &cork, ipc, rtp); 1484 if (err) 1485 return ERR_PTR(err); 1486 1487 err = __ip_append_data(sk, fl4, &queue, &cork, 1488 ¤t->task_frag, getfrag, 1489 from, length, transhdrlen, flags); 1490 if (err) { 1491 __ip_flush_pending_frames(sk, &queue, &cork); 1492 return ERR_PTR(err); 1493 } 1494 1495 return __ip_make_skb(sk, fl4, &queue, &cork); 1496} 1497 1498/* 1499 * Fetch data from kernel space and fill in checksum if needed. 1500 */ 1501static int ip_reply_glue_bits(void *dptr, char *to, int offset, 1502 int len, int odd, struct sk_buff *skb) 1503{ 1504 __wsum csum; 1505 1506 csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0); 1507 skb->csum = csum_block_add(skb->csum, csum, odd); 1508 return 0; 1509} 1510 1511/* 1512 * Generic function to send a packet as reply to another packet. 1513 * Used to send some TCP resets/acks so far. 1514 */ 1515void ip_send_unicast_reply(struct sock *sk, struct sk_buff *skb, 1516 const struct ip_options *sopt, 1517 __be32 daddr, __be32 saddr, 1518 const struct ip_reply_arg *arg, 1519 unsigned int len) 1520{ 1521 struct ip_options_data replyopts; 1522 struct ipcm_cookie ipc; 1523 struct flowi4 fl4; 1524 struct rtable *rt = skb_rtable(skb); 1525 struct net *net = sock_net(sk); 1526 struct sk_buff *nskb; 1527 int err; 1528 1529 if (__ip_options_echo(&replyopts.opt.opt, skb, sopt)) 1530 return; 1531 1532 ipc.addr = daddr; 1533 ipc.opt = NULL; 1534 ipc.tx_flags = 0; 1535 ipc.ttl = 0; 1536 ipc.tos = -1; 1537 1538 if (replyopts.opt.opt.optlen) { 1539 ipc.opt = &replyopts.opt; 1540 1541 if (replyopts.opt.opt.srr) 1542 daddr = replyopts.opt.opt.faddr; 1543 } 1544 1545 flowi4_init_output(&fl4, arg->bound_dev_if, 1546 IP4_REPLY_MARK(net, skb->mark), 1547 RT_TOS(arg->tos), 1548 RT_SCOPE_UNIVERSE, ip_hdr(skb)->protocol, 1549 ip_reply_arg_flowi_flags(arg), 1550 daddr, saddr, 1551 tcp_hdr(skb)->source, tcp_hdr(skb)->dest); 1552 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4)); 1553 rt = ip_route_output_key(net, &fl4); 1554 if (IS_ERR(rt)) 1555 return; 1556 1557 inet_sk(sk)->tos = arg->tos; 1558 1559 sk->sk_priority = skb->priority; 1560 sk->sk_protocol = ip_hdr(skb)->protocol; 1561 sk->sk_bound_dev_if = arg->bound_dev_if; 1562 sk->sk_sndbuf = sysctl_wmem_default; 1563 err = ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base, 1564 len, 0, &ipc, &rt, MSG_DONTWAIT); 1565 if (unlikely(err)) { 1566 ip_flush_pending_frames(sk); 1567 goto out; 1568 } 1569 1570 nskb = skb_peek(&sk->sk_write_queue); 1571 if (nskb) { 1572 if (arg->csumoffset >= 0) 1573 *((__sum16 *)skb_transport_header(nskb) + 1574 arg->csumoffset) = csum_fold(csum_add(nskb->csum, 1575 arg->csum)); 1576 nskb->ip_summed = CHECKSUM_NONE; 1577 skb_set_queue_mapping(nskb, skb_get_queue_mapping(skb)); 1578 ip_push_pending_frames(sk, &fl4); 1579 } 1580out: 1581 ip_rt_put(rt); 1582} 1583 1584void __init ip_init(void) 1585{ 1586 ip_rt_init(); 1587 inet_initpeers(); 1588 1589#if defined(CONFIG_IP_MULTICAST) 1590 igmp_mc_init(); 1591#endif 1592} 1593