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