ip_output.c revision 76ab608d86cf1ef5c5c46819b5733eb9f9f964f8
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 * Version: $Id: ip_output.c,v 1.100 2002/02/01 22:01:03 davem Exp $ 9 * 10 * Authors: Ross Biro 11 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> 12 * Donald Becker, <becker@super.org> 13 * Alan Cox, <Alan.Cox@linux.org> 14 * Richard Underwood 15 * Stefan Becker, <stefanb@yello.ping.de> 16 * Jorge Cwik, <jorge@laser.satlink.net> 17 * Arnt Gulbrandsen, <agulbra@nvg.unit.no> 18 * Hirokazu Takahashi, <taka@valinux.co.jp> 19 * 20 * See ip_input.c for original log 21 * 22 * Fixes: 23 * Alan Cox : Missing nonblock feature in ip_build_xmit. 24 * Mike Kilburn : htons() missing in ip_build_xmit. 25 * Bradford Johnson: Fix faulty handling of some frames when 26 * no route is found. 27 * Alexander Demenshin: Missing sk/skb free in ip_queue_xmit 28 * (in case if packet not accepted by 29 * output firewall rules) 30 * Mike McLagan : Routing by source 31 * Alexey Kuznetsov: use new route cache 32 * Andi Kleen: Fix broken PMTU recovery and remove 33 * some redundant tests. 34 * Vitaly E. Lavrov : Transparent proxy revived after year coma. 35 * Andi Kleen : Replace ip_reply with ip_send_reply. 36 * Andi Kleen : Split fast and slow ip_build_xmit path 37 * for decreased register pressure on x86 38 * and more readibility. 39 * Marc Boucher : When call_out_firewall returns FW_QUEUE, 40 * silently drop skb instead of failing with -EPERM. 41 * Detlev Wengorz : Copy protocol for fragments. 42 * Hirokazu Takahashi: HW checksumming for outgoing UDP 43 * datagrams. 44 * Hirokazu Takahashi: sendfile() on UDP works now. 45 */ 46 47#include <asm/uaccess.h> 48#include <asm/system.h> 49#include <linux/module.h> 50#include <linux/types.h> 51#include <linux/kernel.h> 52#include <linux/sched.h> 53#include <linux/mm.h> 54#include <linux/string.h> 55#include <linux/errno.h> 56#include <linux/config.h> 57 58#include <linux/socket.h> 59#include <linux/sockios.h> 60#include <linux/in.h> 61#include <linux/inet.h> 62#include <linux/netdevice.h> 63#include <linux/etherdevice.h> 64#include <linux/proc_fs.h> 65#include <linux/stat.h> 66#include <linux/init.h> 67 68#include <net/snmp.h> 69#include <net/ip.h> 70#include <net/protocol.h> 71#include <net/route.h> 72#include <linux/skbuff.h> 73#include <net/sock.h> 74#include <net/arp.h> 75#include <net/icmp.h> 76#include <net/checksum.h> 77#include <net/inetpeer.h> 78#include <net/checksum.h> 79#include <linux/igmp.h> 80#include <linux/netfilter_ipv4.h> 81#include <linux/netfilter_bridge.h> 82#include <linux/mroute.h> 83#include <linux/netlink.h> 84#include <linux/tcp.h> 85 86int sysctl_ip_default_ttl = IPDEFTTL; 87 88/* Generate a checksum for an outgoing IP datagram. */ 89__inline__ void ip_send_check(struct iphdr *iph) 90{ 91 iph->check = 0; 92 iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl); 93} 94 95/* dev_loopback_xmit for use with netfilter. */ 96static int ip_dev_loopback_xmit(struct sk_buff *newskb) 97{ 98 newskb->mac.raw = newskb->data; 99 __skb_pull(newskb, newskb->nh.raw - newskb->data); 100 newskb->pkt_type = PACKET_LOOPBACK; 101 newskb->ip_summed = CHECKSUM_UNNECESSARY; 102 BUG_TRAP(newskb->dst); 103 netif_rx(newskb); 104 return 0; 105} 106 107static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst) 108{ 109 int ttl = inet->uc_ttl; 110 111 if (ttl < 0) 112 ttl = dst_metric(dst, RTAX_HOPLIMIT); 113 return ttl; 114} 115 116/* 117 * Add an ip header to a skbuff and send it out. 118 * 119 */ 120int ip_build_and_send_pkt(struct sk_buff *skb, struct sock *sk, 121 u32 saddr, u32 daddr, struct ip_options *opt) 122{ 123 struct inet_sock *inet = inet_sk(sk); 124 struct rtable *rt = (struct rtable *)skb->dst; 125 struct iphdr *iph; 126 127 /* Build the IP header. */ 128 if (opt) 129 iph=(struct iphdr *)skb_push(skb,sizeof(struct iphdr) + opt->optlen); 130 else 131 iph=(struct iphdr *)skb_push(skb,sizeof(struct iphdr)); 132 133 iph->version = 4; 134 iph->ihl = 5; 135 iph->tos = inet->tos; 136 if (ip_dont_fragment(sk, &rt->u.dst)) 137 iph->frag_off = htons(IP_DF); 138 else 139 iph->frag_off = 0; 140 iph->ttl = ip_select_ttl(inet, &rt->u.dst); 141 iph->daddr = rt->rt_dst; 142 iph->saddr = rt->rt_src; 143 iph->protocol = sk->sk_protocol; 144 iph->tot_len = htons(skb->len); 145 ip_select_ident(iph, &rt->u.dst, sk); 146 skb->nh.iph = iph; 147 148 if (opt && opt->optlen) { 149 iph->ihl += opt->optlen>>2; 150 ip_options_build(skb, opt, daddr, rt, 0); 151 } 152 ip_send_check(iph); 153 154 skb->priority = sk->sk_priority; 155 156 /* Send it out. */ 157 return NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, skb, NULL, rt->u.dst.dev, 158 dst_output); 159} 160 161EXPORT_SYMBOL_GPL(ip_build_and_send_pkt); 162 163static inline int ip_finish_output2(struct sk_buff *skb) 164{ 165 struct dst_entry *dst = skb->dst; 166 struct hh_cache *hh = dst->hh; 167 struct net_device *dev = dst->dev; 168 int hh_len = LL_RESERVED_SPACE(dev); 169 170 /* Be paranoid, rather than too clever. */ 171 if (unlikely(skb_headroom(skb) < hh_len && dev->hard_header)) { 172 struct sk_buff *skb2; 173 174 skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev)); 175 if (skb2 == NULL) { 176 kfree_skb(skb); 177 return -ENOMEM; 178 } 179 if (skb->sk) 180 skb_set_owner_w(skb2, skb->sk); 181 kfree_skb(skb); 182 skb = skb2; 183 } 184 185 if (hh) { 186 int hh_alen; 187 188 read_lock_bh(&hh->hh_lock); 189 hh_alen = HH_DATA_ALIGN(hh->hh_len); 190 memcpy(skb->data - hh_alen, hh->hh_data, hh_alen); 191 read_unlock_bh(&hh->hh_lock); 192 skb_push(skb, hh->hh_len); 193 return hh->hh_output(skb); 194 } else if (dst->neighbour) 195 return dst->neighbour->output(skb); 196 197 if (net_ratelimit()) 198 printk(KERN_DEBUG "ip_finish_output2: No header cache and no neighbour!\n"); 199 kfree_skb(skb); 200 return -EINVAL; 201} 202 203static inline int ip_finish_output(struct sk_buff *skb) 204{ 205 if (skb->len > dst_mtu(skb->dst) && 206 !(skb_shinfo(skb)->ufo_size || skb_shinfo(skb)->tso_size)) 207 return ip_fragment(skb, ip_finish_output2); 208 else 209 return ip_finish_output2(skb); 210} 211 212int ip_mc_output(struct sk_buff *skb) 213{ 214 struct sock *sk = skb->sk; 215 struct rtable *rt = (struct rtable*)skb->dst; 216 struct net_device *dev = rt->u.dst.dev; 217 218 /* 219 * If the indicated interface is up and running, send the packet. 220 */ 221 IP_INC_STATS(IPSTATS_MIB_OUTREQUESTS); 222 223 skb->dev = dev; 224 skb->protocol = htons(ETH_P_IP); 225 226 /* 227 * Multicasts are looped back for other local users 228 */ 229 230 if (rt->rt_flags&RTCF_MULTICAST) { 231 if ((!sk || inet_sk(sk)->mc_loop) 232#ifdef CONFIG_IP_MROUTE 233 /* Small optimization: do not loopback not local frames, 234 which returned after forwarding; they will be dropped 235 by ip_mr_input in any case. 236 Note, that local frames are looped back to be delivered 237 to local recipients. 238 239 This check is duplicated in ip_mr_input at the moment. 240 */ 241 && ((rt->rt_flags&RTCF_LOCAL) || !(IPCB(skb)->flags&IPSKB_FORWARDED)) 242#endif 243 ) { 244 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC); 245 if (newskb) 246 NF_HOOK(PF_INET, NF_IP_POST_ROUTING, newskb, NULL, 247 newskb->dev, 248 ip_dev_loopback_xmit); 249 } 250 251 /* Multicasts with ttl 0 must not go beyond the host */ 252 253 if (skb->nh.iph->ttl == 0) { 254 kfree_skb(skb); 255 return 0; 256 } 257 } 258 259 if (rt->rt_flags&RTCF_BROADCAST) { 260 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC); 261 if (newskb) 262 NF_HOOK(PF_INET, NF_IP_POST_ROUTING, newskb, NULL, 263 newskb->dev, ip_dev_loopback_xmit); 264 } 265 266 return NF_HOOK(PF_INET, NF_IP_POST_ROUTING, skb, NULL, skb->dev, 267 ip_finish_output); 268} 269 270int ip_output(struct sk_buff *skb) 271{ 272 struct net_device *dev = skb->dst->dev; 273 274 IP_INC_STATS(IPSTATS_MIB_OUTREQUESTS); 275 276 skb->dev = dev; 277 skb->protocol = htons(ETH_P_IP); 278 279 return NF_HOOK(PF_INET, NF_IP_POST_ROUTING, skb, NULL, dev, 280 ip_finish_output); 281} 282 283int ip_queue_xmit(struct sk_buff *skb, int ipfragok) 284{ 285 struct sock *sk = skb->sk; 286 struct inet_sock *inet = inet_sk(sk); 287 struct ip_options *opt = inet->opt; 288 struct rtable *rt; 289 struct iphdr *iph; 290 291 /* Skip all of this if the packet is already routed, 292 * f.e. by something like SCTP. 293 */ 294 rt = (struct rtable *) skb->dst; 295 if (rt != NULL) 296 goto packet_routed; 297 298 /* Make sure we can route this packet. */ 299 rt = (struct rtable *)__sk_dst_check(sk, 0); 300 if (rt == NULL) { 301 u32 daddr; 302 303 /* Use correct destination address if we have options. */ 304 daddr = inet->daddr; 305 if(opt && opt->srr) 306 daddr = opt->faddr; 307 308 { 309 struct flowi fl = { .oif = sk->sk_bound_dev_if, 310 .nl_u = { .ip4_u = 311 { .daddr = daddr, 312 .saddr = inet->saddr, 313 .tos = RT_CONN_FLAGS(sk) } }, 314 .proto = sk->sk_protocol, 315 .uli_u = { .ports = 316 { .sport = inet->sport, 317 .dport = inet->dport } } }; 318 319 /* If this fails, retransmit mechanism of transport layer will 320 * keep trying until route appears or the connection times 321 * itself out. 322 */ 323 if (ip_route_output_flow(&rt, &fl, sk, 0)) 324 goto no_route; 325 } 326 sk_setup_caps(sk, &rt->u.dst); 327 } 328 skb->dst = dst_clone(&rt->u.dst); 329 330packet_routed: 331 if (opt && opt->is_strictroute && rt->rt_dst != rt->rt_gateway) 332 goto no_route; 333 334 /* OK, we know where to send it, allocate and build IP header. */ 335 iph = (struct iphdr *) skb_push(skb, sizeof(struct iphdr) + (opt ? opt->optlen : 0)); 336 *((__u16 *)iph) = htons((4 << 12) | (5 << 8) | (inet->tos & 0xff)); 337 iph->tot_len = htons(skb->len); 338 if (ip_dont_fragment(sk, &rt->u.dst) && !ipfragok) 339 iph->frag_off = htons(IP_DF); 340 else 341 iph->frag_off = 0; 342 iph->ttl = ip_select_ttl(inet, &rt->u.dst); 343 iph->protocol = sk->sk_protocol; 344 iph->saddr = rt->rt_src; 345 iph->daddr = rt->rt_dst; 346 skb->nh.iph = iph; 347 /* Transport layer set skb->h.foo itself. */ 348 349 if (opt && opt->optlen) { 350 iph->ihl += opt->optlen >> 2; 351 ip_options_build(skb, opt, inet->daddr, rt, 0); 352 } 353 354 ip_select_ident_more(iph, &rt->u.dst, sk, 355 (skb_shinfo(skb)->tso_segs ?: 1) - 1); 356 357 /* Add an IP checksum. */ 358 ip_send_check(iph); 359 360 skb->priority = sk->sk_priority; 361 362 return NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, skb, NULL, rt->u.dst.dev, 363 dst_output); 364 365no_route: 366 IP_INC_STATS(IPSTATS_MIB_OUTNOROUTES); 367 kfree_skb(skb); 368 return -EHOSTUNREACH; 369} 370 371 372static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from) 373{ 374 to->pkt_type = from->pkt_type; 375 to->priority = from->priority; 376 to->protocol = from->protocol; 377 dst_release(to->dst); 378 to->dst = dst_clone(from->dst); 379 to->dev = from->dev; 380 381 /* Copy the flags to each fragment. */ 382 IPCB(to)->flags = IPCB(from)->flags; 383 384#ifdef CONFIG_NET_SCHED 385 to->tc_index = from->tc_index; 386#endif 387#ifdef CONFIG_NETFILTER 388 to->nfmark = from->nfmark; 389 /* Connection association is same as pre-frag packet */ 390 nf_conntrack_put(to->nfct); 391 to->nfct = from->nfct; 392 nf_conntrack_get(to->nfct); 393 to->nfctinfo = from->nfctinfo; 394#if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE) 395 to->ipvs_property = from->ipvs_property; 396#endif 397#ifdef CONFIG_BRIDGE_NETFILTER 398 nf_bridge_put(to->nf_bridge); 399 to->nf_bridge = from->nf_bridge; 400 nf_bridge_get(to->nf_bridge); 401#endif 402#endif 403} 404 405/* 406 * This IP datagram is too large to be sent in one piece. Break it up into 407 * smaller pieces (each of size equal to IP header plus 408 * a block of the data of the original IP data part) that will yet fit in a 409 * single device frame, and queue such a frame for sending. 410 */ 411 412int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff*)) 413{ 414 struct iphdr *iph; 415 int raw = 0; 416 int ptr; 417 struct net_device *dev; 418 struct sk_buff *skb2; 419 unsigned int mtu, hlen, left, len, ll_rs; 420 int offset; 421 __be16 not_last_frag; 422 struct rtable *rt = (struct rtable*)skb->dst; 423 int err = 0; 424 425 dev = rt->u.dst.dev; 426 427 /* 428 * Point into the IP datagram header. 429 */ 430 431 iph = skb->nh.iph; 432 433 if (unlikely((iph->frag_off & htons(IP_DF)) && !skb->local_df)) { 434 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, 435 htonl(dst_mtu(&rt->u.dst))); 436 kfree_skb(skb); 437 return -EMSGSIZE; 438 } 439 440 /* 441 * Setup starting values. 442 */ 443 444 hlen = iph->ihl * 4; 445 mtu = dst_mtu(&rt->u.dst) - hlen; /* Size of data space */ 446 IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE; 447 448 /* When frag_list is given, use it. First, check its validity: 449 * some transformers could create wrong frag_list or break existing 450 * one, it is not prohibited. In this case fall back to copying. 451 * 452 * LATER: this step can be merged to real generation of fragments, 453 * we can switch to copy when see the first bad fragment. 454 */ 455 if (skb_shinfo(skb)->frag_list) { 456 struct sk_buff *frag; 457 int first_len = skb_pagelen(skb); 458 459 if (first_len - hlen > mtu || 460 ((first_len - hlen) & 7) || 461 (iph->frag_off & htons(IP_MF|IP_OFFSET)) || 462 skb_cloned(skb)) 463 goto slow_path; 464 465 for (frag = skb_shinfo(skb)->frag_list; frag; frag = frag->next) { 466 /* Correct geometry. */ 467 if (frag->len > mtu || 468 ((frag->len & 7) && frag->next) || 469 skb_headroom(frag) < hlen) 470 goto slow_path; 471 472 /* Partially cloned skb? */ 473 if (skb_shared(frag)) 474 goto slow_path; 475 476 BUG_ON(frag->sk); 477 if (skb->sk) { 478 sock_hold(skb->sk); 479 frag->sk = skb->sk; 480 frag->destructor = sock_wfree; 481 skb->truesize -= frag->truesize; 482 } 483 } 484 485 /* Everything is OK. Generate! */ 486 487 err = 0; 488 offset = 0; 489 frag = skb_shinfo(skb)->frag_list; 490 skb_shinfo(skb)->frag_list = NULL; 491 skb->data_len = first_len - skb_headlen(skb); 492 skb->len = first_len; 493 iph->tot_len = htons(first_len); 494 iph->frag_off = htons(IP_MF); 495 ip_send_check(iph); 496 497 for (;;) { 498 /* Prepare header of the next frame, 499 * before previous one went down. */ 500 if (frag) { 501 frag->ip_summed = CHECKSUM_NONE; 502 frag->h.raw = frag->data; 503 frag->nh.raw = __skb_push(frag, hlen); 504 memcpy(frag->nh.raw, iph, hlen); 505 iph = frag->nh.iph; 506 iph->tot_len = htons(frag->len); 507 ip_copy_metadata(frag, skb); 508 if (offset == 0) 509 ip_options_fragment(frag); 510 offset += skb->len - hlen; 511 iph->frag_off = htons(offset>>3); 512 if (frag->next != NULL) 513 iph->frag_off |= htons(IP_MF); 514 /* Ready, complete checksum */ 515 ip_send_check(iph); 516 } 517 518 err = output(skb); 519 520 if (err || !frag) 521 break; 522 523 skb = frag; 524 frag = skb->next; 525 skb->next = NULL; 526 } 527 528 if (err == 0) { 529 IP_INC_STATS(IPSTATS_MIB_FRAGOKS); 530 return 0; 531 } 532 533 while (frag) { 534 skb = frag->next; 535 kfree_skb(frag); 536 frag = skb; 537 } 538 IP_INC_STATS(IPSTATS_MIB_FRAGFAILS); 539 return err; 540 } 541 542slow_path: 543 left = skb->len - hlen; /* Space per frame */ 544 ptr = raw + hlen; /* Where to start from */ 545 546#ifdef CONFIG_BRIDGE_NETFILTER 547 /* for bridged IP traffic encapsulated inside f.e. a vlan header, 548 * we need to make room for the encapsulating header */ 549 ll_rs = LL_RESERVED_SPACE_EXTRA(rt->u.dst.dev, nf_bridge_pad(skb)); 550 mtu -= nf_bridge_pad(skb); 551#else 552 ll_rs = LL_RESERVED_SPACE(rt->u.dst.dev); 553#endif 554 /* 555 * Fragment the datagram. 556 */ 557 558 offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3; 559 not_last_frag = iph->frag_off & htons(IP_MF); 560 561 /* 562 * Keep copying data until we run out. 563 */ 564 565 while(left > 0) { 566 len = left; 567 /* IF: it doesn't fit, use 'mtu' - the data space left */ 568 if (len > mtu) 569 len = mtu; 570 /* IF: we are not sending upto and including the packet end 571 then align the next start on an eight byte boundary */ 572 if (len < left) { 573 len &= ~7; 574 } 575 /* 576 * Allocate buffer. 577 */ 578 579 if ((skb2 = alloc_skb(len+hlen+ll_rs, GFP_ATOMIC)) == NULL) { 580 NETDEBUG(KERN_INFO "IP: frag: no memory for new fragment!\n"); 581 err = -ENOMEM; 582 goto fail; 583 } 584 585 /* 586 * Set up data on packet 587 */ 588 589 ip_copy_metadata(skb2, skb); 590 skb_reserve(skb2, ll_rs); 591 skb_put(skb2, len + hlen); 592 skb2->nh.raw = skb2->data; 593 skb2->h.raw = skb2->data + hlen; 594 595 /* 596 * Charge the memory for the fragment to any owner 597 * it might possess 598 */ 599 600 if (skb->sk) 601 skb_set_owner_w(skb2, skb->sk); 602 603 /* 604 * Copy the packet header into the new buffer. 605 */ 606 607 memcpy(skb2->nh.raw, skb->data, hlen); 608 609 /* 610 * Copy a block of the IP datagram. 611 */ 612 if (skb_copy_bits(skb, ptr, skb2->h.raw, len)) 613 BUG(); 614 left -= len; 615 616 /* 617 * Fill in the new header fields. 618 */ 619 iph = skb2->nh.iph; 620 iph->frag_off = htons((offset >> 3)); 621 622 /* ANK: dirty, but effective trick. Upgrade options only if 623 * the segment to be fragmented was THE FIRST (otherwise, 624 * options are already fixed) and make it ONCE 625 * on the initial skb, so that all the following fragments 626 * will inherit fixed options. 627 */ 628 if (offset == 0) 629 ip_options_fragment(skb); 630 631 /* 632 * Added AC : If we are fragmenting a fragment that's not the 633 * last fragment then keep MF on each bit 634 */ 635 if (left > 0 || not_last_frag) 636 iph->frag_off |= htons(IP_MF); 637 ptr += len; 638 offset += len; 639 640 /* 641 * Put this fragment into the sending queue. 642 */ 643 644 IP_INC_STATS(IPSTATS_MIB_FRAGCREATES); 645 646 iph->tot_len = htons(len + hlen); 647 648 ip_send_check(iph); 649 650 err = output(skb2); 651 if (err) 652 goto fail; 653 } 654 kfree_skb(skb); 655 IP_INC_STATS(IPSTATS_MIB_FRAGOKS); 656 return err; 657 658fail: 659 kfree_skb(skb); 660 IP_INC_STATS(IPSTATS_MIB_FRAGFAILS); 661 return err; 662} 663 664int 665ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb) 666{ 667 struct iovec *iov = from; 668 669 if (skb->ip_summed == CHECKSUM_HW) { 670 if (memcpy_fromiovecend(to, iov, offset, len) < 0) 671 return -EFAULT; 672 } else { 673 unsigned int csum = 0; 674 if (csum_partial_copy_fromiovecend(to, iov, offset, len, &csum) < 0) 675 return -EFAULT; 676 skb->csum = csum_block_add(skb->csum, csum, odd); 677 } 678 return 0; 679} 680 681static inline unsigned int 682csum_page(struct page *page, int offset, int copy) 683{ 684 char *kaddr; 685 unsigned int csum; 686 kaddr = kmap(page); 687 csum = csum_partial(kaddr + offset, copy, 0); 688 kunmap(page); 689 return csum; 690} 691 692static inline int ip_ufo_append_data(struct sock *sk, 693 int getfrag(void *from, char *to, int offset, int len, 694 int odd, struct sk_buff *skb), 695 void *from, int length, int hh_len, int fragheaderlen, 696 int transhdrlen, int mtu,unsigned int flags) 697{ 698 struct sk_buff *skb; 699 int err; 700 701 /* There is support for UDP fragmentation offload by network 702 * device, so create one single skb packet containing complete 703 * udp datagram 704 */ 705 if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL) { 706 skb = sock_alloc_send_skb(sk, 707 hh_len + fragheaderlen + transhdrlen + 20, 708 (flags & MSG_DONTWAIT), &err); 709 710 if (skb == NULL) 711 return err; 712 713 /* reserve space for Hardware header */ 714 skb_reserve(skb, hh_len); 715 716 /* create space for UDP/IP header */ 717 skb_put(skb,fragheaderlen + transhdrlen); 718 719 /* initialize network header pointer */ 720 skb->nh.raw = skb->data; 721 722 /* initialize protocol header pointer */ 723 skb->h.raw = skb->data + fragheaderlen; 724 725 skb->ip_summed = CHECKSUM_HW; 726 skb->csum = 0; 727 sk->sk_sndmsg_off = 0; 728 } 729 730 err = skb_append_datato_frags(sk,skb, getfrag, from, 731 (length - transhdrlen)); 732 if (!err) { 733 /* specify the length of each IP datagram fragment*/ 734 skb_shinfo(skb)->ufo_size = (mtu - fragheaderlen); 735 __skb_queue_tail(&sk->sk_write_queue, skb); 736 737 return 0; 738 } 739 /* There is not enough support do UFO , 740 * so follow normal path 741 */ 742 kfree_skb(skb); 743 return err; 744} 745 746/* 747 * ip_append_data() and ip_append_page() can make one large IP datagram 748 * from many pieces of data. Each pieces will be holded on the socket 749 * until ip_push_pending_frames() is called. Each piece can be a page 750 * or non-page data. 751 * 752 * Not only UDP, other transport protocols - e.g. raw sockets - can use 753 * this interface potentially. 754 * 755 * LATER: length must be adjusted by pad at tail, when it is required. 756 */ 757int ip_append_data(struct sock *sk, 758 int getfrag(void *from, char *to, int offset, int len, 759 int odd, struct sk_buff *skb), 760 void *from, int length, int transhdrlen, 761 struct ipcm_cookie *ipc, struct rtable *rt, 762 unsigned int flags) 763{ 764 struct inet_sock *inet = inet_sk(sk); 765 struct sk_buff *skb; 766 767 struct ip_options *opt = NULL; 768 int hh_len; 769 int exthdrlen; 770 int mtu; 771 int copy; 772 int err; 773 int offset = 0; 774 unsigned int maxfraglen, fragheaderlen; 775 int csummode = CHECKSUM_NONE; 776 777 if (flags&MSG_PROBE) 778 return 0; 779 780 if (skb_queue_empty(&sk->sk_write_queue)) { 781 /* 782 * setup for corking. 783 */ 784 opt = ipc->opt; 785 if (opt) { 786 if (inet->cork.opt == NULL) { 787 inet->cork.opt = kmalloc(sizeof(struct ip_options) + 40, sk->sk_allocation); 788 if (unlikely(inet->cork.opt == NULL)) 789 return -ENOBUFS; 790 } 791 memcpy(inet->cork.opt, opt, sizeof(struct ip_options)+opt->optlen); 792 inet->cork.flags |= IPCORK_OPT; 793 inet->cork.addr = ipc->addr; 794 } 795 dst_hold(&rt->u.dst); 796 inet->cork.fragsize = mtu = dst_mtu(rt->u.dst.path); 797 inet->cork.rt = rt; 798 inet->cork.length = 0; 799 sk->sk_sndmsg_page = NULL; 800 sk->sk_sndmsg_off = 0; 801 if ((exthdrlen = rt->u.dst.header_len) != 0) { 802 length += exthdrlen; 803 transhdrlen += exthdrlen; 804 } 805 } else { 806 rt = inet->cork.rt; 807 if (inet->cork.flags & IPCORK_OPT) 808 opt = inet->cork.opt; 809 810 transhdrlen = 0; 811 exthdrlen = 0; 812 mtu = inet->cork.fragsize; 813 } 814 hh_len = LL_RESERVED_SPACE(rt->u.dst.dev); 815 816 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0); 817 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen; 818 819 if (inet->cork.length + length > 0xFFFF - fragheaderlen) { 820 ip_local_error(sk, EMSGSIZE, rt->rt_dst, inet->dport, mtu-exthdrlen); 821 return -EMSGSIZE; 822 } 823 824 /* 825 * transhdrlen > 0 means that this is the first fragment and we wish 826 * it won't be fragmented in the future. 827 */ 828 if (transhdrlen && 829 length + fragheaderlen <= mtu && 830 rt->u.dst.dev->features&(NETIF_F_IP_CSUM|NETIF_F_NO_CSUM|NETIF_F_HW_CSUM) && 831 !exthdrlen) 832 csummode = CHECKSUM_HW; 833 834 inet->cork.length += length; 835 if (((length > mtu) && (sk->sk_protocol == IPPROTO_UDP)) && 836 (rt->u.dst.dev->features & NETIF_F_UFO)) { 837 838 if(ip_ufo_append_data(sk, getfrag, from, length, hh_len, 839 fragheaderlen, transhdrlen, mtu, flags)) 840 goto error; 841 842 return 0; 843 } 844 845 /* So, what's going on in the loop below? 846 * 847 * We use calculated fragment length to generate chained skb, 848 * each of segments is IP fragment ready for sending to network after 849 * adding appropriate IP header. 850 */ 851 852 if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL) 853 goto alloc_new_skb; 854 855 while (length > 0) { 856 /* Check if the remaining data fits into current packet. */ 857 copy = mtu - skb->len; 858 if (copy < length) 859 copy = maxfraglen - skb->len; 860 if (copy <= 0) { 861 char *data; 862 unsigned int datalen; 863 unsigned int fraglen; 864 unsigned int fraggap; 865 unsigned int alloclen; 866 struct sk_buff *skb_prev; 867alloc_new_skb: 868 skb_prev = skb; 869 if (skb_prev) 870 fraggap = skb_prev->len - maxfraglen; 871 else 872 fraggap = 0; 873 874 /* 875 * If remaining data exceeds the mtu, 876 * we know we need more fragment(s). 877 */ 878 datalen = length + fraggap; 879 if (datalen > mtu - fragheaderlen) 880 datalen = maxfraglen - fragheaderlen; 881 fraglen = datalen + fragheaderlen; 882 883 if ((flags & MSG_MORE) && 884 !(rt->u.dst.dev->features&NETIF_F_SG)) 885 alloclen = mtu; 886 else 887 alloclen = datalen + fragheaderlen; 888 889 /* The last fragment gets additional space at tail. 890 * Note, with MSG_MORE we overallocate on fragments, 891 * because we have no idea what fragment will be 892 * the last. 893 */ 894 if (datalen == length) 895 alloclen += rt->u.dst.trailer_len; 896 897 if (transhdrlen) { 898 skb = sock_alloc_send_skb(sk, 899 alloclen + hh_len + 15, 900 (flags & MSG_DONTWAIT), &err); 901 } else { 902 skb = NULL; 903 if (atomic_read(&sk->sk_wmem_alloc) <= 904 2 * sk->sk_sndbuf) 905 skb = sock_wmalloc(sk, 906 alloclen + hh_len + 15, 1, 907 sk->sk_allocation); 908 if (unlikely(skb == NULL)) 909 err = -ENOBUFS; 910 } 911 if (skb == NULL) 912 goto error; 913 914 /* 915 * Fill in the control structures 916 */ 917 skb->ip_summed = csummode; 918 skb->csum = 0; 919 skb_reserve(skb, hh_len); 920 921 /* 922 * Find where to start putting bytes. 923 */ 924 data = skb_put(skb, fraglen); 925 skb->nh.raw = data + exthdrlen; 926 data += fragheaderlen; 927 skb->h.raw = data + exthdrlen; 928 929 if (fraggap) { 930 skb->csum = skb_copy_and_csum_bits( 931 skb_prev, maxfraglen, 932 data + transhdrlen, fraggap, 0); 933 skb_prev->csum = csum_sub(skb_prev->csum, 934 skb->csum); 935 data += fraggap; 936 skb_trim(skb_prev, maxfraglen); 937 } 938 939 copy = datalen - transhdrlen - fraggap; 940 if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) { 941 err = -EFAULT; 942 kfree_skb(skb); 943 goto error; 944 } 945 946 offset += copy; 947 length -= datalen - fraggap; 948 transhdrlen = 0; 949 exthdrlen = 0; 950 csummode = CHECKSUM_NONE; 951 952 /* 953 * Put the packet on the pending queue. 954 */ 955 __skb_queue_tail(&sk->sk_write_queue, skb); 956 continue; 957 } 958 959 if (copy > length) 960 copy = length; 961 962 if (!(rt->u.dst.dev->features&NETIF_F_SG)) { 963 unsigned int off; 964 965 off = skb->len; 966 if (getfrag(from, skb_put(skb, copy), 967 offset, copy, off, skb) < 0) { 968 __skb_trim(skb, off); 969 err = -EFAULT; 970 goto error; 971 } 972 } else { 973 int i = skb_shinfo(skb)->nr_frags; 974 skb_frag_t *frag = &skb_shinfo(skb)->frags[i-1]; 975 struct page *page = sk->sk_sndmsg_page; 976 int off = sk->sk_sndmsg_off; 977 unsigned int left; 978 979 if (page && (left = PAGE_SIZE - off) > 0) { 980 if (copy >= left) 981 copy = left; 982 if (page != frag->page) { 983 if (i == MAX_SKB_FRAGS) { 984 err = -EMSGSIZE; 985 goto error; 986 } 987 get_page(page); 988 skb_fill_page_desc(skb, i, page, sk->sk_sndmsg_off, 0); 989 frag = &skb_shinfo(skb)->frags[i]; 990 } 991 } else if (i < MAX_SKB_FRAGS) { 992 if (copy > PAGE_SIZE) 993 copy = PAGE_SIZE; 994 page = alloc_pages(sk->sk_allocation, 0); 995 if (page == NULL) { 996 err = -ENOMEM; 997 goto error; 998 } 999 sk->sk_sndmsg_page = page; 1000 sk->sk_sndmsg_off = 0; 1001 1002 skb_fill_page_desc(skb, i, page, 0, 0); 1003 frag = &skb_shinfo(skb)->frags[i]; 1004 skb->truesize += PAGE_SIZE; 1005 atomic_add(PAGE_SIZE, &sk->sk_wmem_alloc); 1006 } else { 1007 err = -EMSGSIZE; 1008 goto error; 1009 } 1010 if (getfrag(from, page_address(frag->page)+frag->page_offset+frag->size, offset, copy, skb->len, skb) < 0) { 1011 err = -EFAULT; 1012 goto error; 1013 } 1014 sk->sk_sndmsg_off += copy; 1015 frag->size += copy; 1016 skb->len += copy; 1017 skb->data_len += copy; 1018 } 1019 offset += copy; 1020 length -= copy; 1021 } 1022 1023 return 0; 1024 1025error: 1026 inet->cork.length -= length; 1027 IP_INC_STATS(IPSTATS_MIB_OUTDISCARDS); 1028 return err; 1029} 1030 1031ssize_t ip_append_page(struct sock *sk, struct page *page, 1032 int offset, size_t size, int flags) 1033{ 1034 struct inet_sock *inet = inet_sk(sk); 1035 struct sk_buff *skb; 1036 struct rtable *rt; 1037 struct ip_options *opt = NULL; 1038 int hh_len; 1039 int mtu; 1040 int len; 1041 int err; 1042 unsigned int maxfraglen, fragheaderlen, fraggap; 1043 1044 if (inet->hdrincl) 1045 return -EPERM; 1046 1047 if (flags&MSG_PROBE) 1048 return 0; 1049 1050 if (skb_queue_empty(&sk->sk_write_queue)) 1051 return -EINVAL; 1052 1053 rt = inet->cork.rt; 1054 if (inet->cork.flags & IPCORK_OPT) 1055 opt = inet->cork.opt; 1056 1057 if (!(rt->u.dst.dev->features&NETIF_F_SG)) 1058 return -EOPNOTSUPP; 1059 1060 hh_len = LL_RESERVED_SPACE(rt->u.dst.dev); 1061 mtu = inet->cork.fragsize; 1062 1063 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0); 1064 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen; 1065 1066 if (inet->cork.length + size > 0xFFFF - fragheaderlen) { 1067 ip_local_error(sk, EMSGSIZE, rt->rt_dst, inet->dport, mtu); 1068 return -EMSGSIZE; 1069 } 1070 1071 if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL) 1072 return -EINVAL; 1073 1074 inet->cork.length += size; 1075 if ((sk->sk_protocol == IPPROTO_UDP) && 1076 (rt->u.dst.dev->features & NETIF_F_UFO)) 1077 skb_shinfo(skb)->ufo_size = (mtu - fragheaderlen); 1078 1079 1080 while (size > 0) { 1081 int i; 1082 1083 if (skb_shinfo(skb)->ufo_size) 1084 len = size; 1085 else { 1086 1087 /* Check if the remaining data fits into current packet. */ 1088 len = mtu - skb->len; 1089 if (len < size) 1090 len = maxfraglen - skb->len; 1091 } 1092 if (len <= 0) { 1093 struct sk_buff *skb_prev; 1094 char *data; 1095 struct iphdr *iph; 1096 int alloclen; 1097 1098 skb_prev = skb; 1099 fraggap = skb_prev->len - maxfraglen; 1100 1101 alloclen = fragheaderlen + hh_len + fraggap + 15; 1102 skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation); 1103 if (unlikely(!skb)) { 1104 err = -ENOBUFS; 1105 goto error; 1106 } 1107 1108 /* 1109 * Fill in the control structures 1110 */ 1111 skb->ip_summed = CHECKSUM_NONE; 1112 skb->csum = 0; 1113 skb_reserve(skb, hh_len); 1114 1115 /* 1116 * Find where to start putting bytes. 1117 */ 1118 data = skb_put(skb, fragheaderlen + fraggap); 1119 skb->nh.iph = iph = (struct iphdr *)data; 1120 data += fragheaderlen; 1121 skb->h.raw = data; 1122 1123 if (fraggap) { 1124 skb->csum = skb_copy_and_csum_bits( 1125 skb_prev, maxfraglen, 1126 data, fraggap, 0); 1127 skb_prev->csum = csum_sub(skb_prev->csum, 1128 skb->csum); 1129 skb_trim(skb_prev, maxfraglen); 1130 } 1131 1132 /* 1133 * Put the packet on the pending queue. 1134 */ 1135 __skb_queue_tail(&sk->sk_write_queue, skb); 1136 continue; 1137 } 1138 1139 i = skb_shinfo(skb)->nr_frags; 1140 if (len > size) 1141 len = size; 1142 if (skb_can_coalesce(skb, i, page, offset)) { 1143 skb_shinfo(skb)->frags[i-1].size += len; 1144 } else if (i < MAX_SKB_FRAGS) { 1145 get_page(page); 1146 skb_fill_page_desc(skb, i, page, offset, len); 1147 } else { 1148 err = -EMSGSIZE; 1149 goto error; 1150 } 1151 1152 if (skb->ip_summed == CHECKSUM_NONE) { 1153 unsigned int csum; 1154 csum = csum_page(page, offset, len); 1155 skb->csum = csum_block_add(skb->csum, csum, skb->len); 1156 } 1157 1158 skb->len += len; 1159 skb->data_len += len; 1160 offset += len; 1161 size -= len; 1162 } 1163 return 0; 1164 1165error: 1166 inet->cork.length -= size; 1167 IP_INC_STATS(IPSTATS_MIB_OUTDISCARDS); 1168 return err; 1169} 1170 1171/* 1172 * Combined all pending IP fragments on the socket as one IP datagram 1173 * and push them out. 1174 */ 1175int ip_push_pending_frames(struct sock *sk) 1176{ 1177 struct sk_buff *skb, *tmp_skb; 1178 struct sk_buff **tail_skb; 1179 struct inet_sock *inet = inet_sk(sk); 1180 struct ip_options *opt = NULL; 1181 struct rtable *rt = inet->cork.rt; 1182 struct iphdr *iph; 1183 __be16 df = 0; 1184 __u8 ttl; 1185 int err = 0; 1186 1187 if ((skb = __skb_dequeue(&sk->sk_write_queue)) == NULL) 1188 goto out; 1189 tail_skb = &(skb_shinfo(skb)->frag_list); 1190 1191 /* move skb->data to ip header from ext header */ 1192 if (skb->data < skb->nh.raw) 1193 __skb_pull(skb, skb->nh.raw - skb->data); 1194 while ((tmp_skb = __skb_dequeue(&sk->sk_write_queue)) != NULL) { 1195 __skb_pull(tmp_skb, skb->h.raw - skb->nh.raw); 1196 *tail_skb = tmp_skb; 1197 tail_skb = &(tmp_skb->next); 1198 skb->len += tmp_skb->len; 1199 skb->data_len += tmp_skb->len; 1200 skb->truesize += tmp_skb->truesize; 1201 __sock_put(tmp_skb->sk); 1202 tmp_skb->destructor = NULL; 1203 tmp_skb->sk = NULL; 1204 } 1205 1206 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow 1207 * to fragment the frame generated here. No matter, what transforms 1208 * how transforms change size of the packet, it will come out. 1209 */ 1210 if (inet->pmtudisc != IP_PMTUDISC_DO) 1211 skb->local_df = 1; 1212 1213 /* DF bit is set when we want to see DF on outgoing frames. 1214 * If local_df is set too, we still allow to fragment this frame 1215 * locally. */ 1216 if (inet->pmtudisc == IP_PMTUDISC_DO || 1217 (skb->len <= dst_mtu(&rt->u.dst) && 1218 ip_dont_fragment(sk, &rt->u.dst))) 1219 df = htons(IP_DF); 1220 1221 if (inet->cork.flags & IPCORK_OPT) 1222 opt = inet->cork.opt; 1223 1224 if (rt->rt_type == RTN_MULTICAST) 1225 ttl = inet->mc_ttl; 1226 else 1227 ttl = ip_select_ttl(inet, &rt->u.dst); 1228 1229 iph = (struct iphdr *)skb->data; 1230 iph->version = 4; 1231 iph->ihl = 5; 1232 if (opt) { 1233 iph->ihl += opt->optlen>>2; 1234 ip_options_build(skb, opt, inet->cork.addr, rt, 0); 1235 } 1236 iph->tos = inet->tos; 1237 iph->tot_len = htons(skb->len); 1238 iph->frag_off = df; 1239 if (!df) { 1240 __ip_select_ident(iph, &rt->u.dst, 0); 1241 } else { 1242 iph->id = htons(inet->id++); 1243 } 1244 iph->ttl = ttl; 1245 iph->protocol = sk->sk_protocol; 1246 iph->saddr = rt->rt_src; 1247 iph->daddr = rt->rt_dst; 1248 ip_send_check(iph); 1249 1250 skb->priority = sk->sk_priority; 1251 skb->dst = dst_clone(&rt->u.dst); 1252 1253 /* Netfilter gets whole the not fragmented skb. */ 1254 err = NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, skb, NULL, 1255 skb->dst->dev, dst_output); 1256 if (err) { 1257 if (err > 0) 1258 err = inet->recverr ? net_xmit_errno(err) : 0; 1259 if (err) 1260 goto error; 1261 } 1262 1263out: 1264 inet->cork.flags &= ~IPCORK_OPT; 1265 kfree(inet->cork.opt); 1266 inet->cork.opt = NULL; 1267 if (inet->cork.rt) { 1268 ip_rt_put(inet->cork.rt); 1269 inet->cork.rt = NULL; 1270 } 1271 return err; 1272 1273error: 1274 IP_INC_STATS(IPSTATS_MIB_OUTDISCARDS); 1275 goto out; 1276} 1277 1278/* 1279 * Throw away all pending data on the socket. 1280 */ 1281void ip_flush_pending_frames(struct sock *sk) 1282{ 1283 struct inet_sock *inet = inet_sk(sk); 1284 struct sk_buff *skb; 1285 1286 while ((skb = __skb_dequeue_tail(&sk->sk_write_queue)) != NULL) 1287 kfree_skb(skb); 1288 1289 inet->cork.flags &= ~IPCORK_OPT; 1290 kfree(inet->cork.opt); 1291 inet->cork.opt = NULL; 1292 if (inet->cork.rt) { 1293 ip_rt_put(inet->cork.rt); 1294 inet->cork.rt = NULL; 1295 } 1296} 1297 1298 1299/* 1300 * Fetch data from kernel space and fill in checksum if needed. 1301 */ 1302static int ip_reply_glue_bits(void *dptr, char *to, int offset, 1303 int len, int odd, struct sk_buff *skb) 1304{ 1305 unsigned int csum; 1306 1307 csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0); 1308 skb->csum = csum_block_add(skb->csum, csum, odd); 1309 return 0; 1310} 1311 1312/* 1313 * Generic function to send a packet as reply to another packet. 1314 * Used to send TCP resets so far. ICMP should use this function too. 1315 * 1316 * Should run single threaded per socket because it uses the sock 1317 * structure to pass arguments. 1318 * 1319 * LATER: switch from ip_build_xmit to ip_append_* 1320 */ 1321void ip_send_reply(struct sock *sk, struct sk_buff *skb, struct ip_reply_arg *arg, 1322 unsigned int len) 1323{ 1324 struct inet_sock *inet = inet_sk(sk); 1325 struct { 1326 struct ip_options opt; 1327 char data[40]; 1328 } replyopts; 1329 struct ipcm_cookie ipc; 1330 u32 daddr; 1331 struct rtable *rt = (struct rtable*)skb->dst; 1332 1333 if (ip_options_echo(&replyopts.opt, skb)) 1334 return; 1335 1336 daddr = ipc.addr = rt->rt_src; 1337 ipc.opt = NULL; 1338 1339 if (replyopts.opt.optlen) { 1340 ipc.opt = &replyopts.opt; 1341 1342 if (ipc.opt->srr) 1343 daddr = replyopts.opt.faddr; 1344 } 1345 1346 { 1347 struct flowi fl = { .nl_u = { .ip4_u = 1348 { .daddr = daddr, 1349 .saddr = rt->rt_spec_dst, 1350 .tos = RT_TOS(skb->nh.iph->tos) } }, 1351 /* Not quite clean, but right. */ 1352 .uli_u = { .ports = 1353 { .sport = skb->h.th->dest, 1354 .dport = skb->h.th->source } }, 1355 .proto = sk->sk_protocol }; 1356 if (ip_route_output_key(&rt, &fl)) 1357 return; 1358 } 1359 1360 /* And let IP do all the hard work. 1361 1362 This chunk is not reenterable, hence spinlock. 1363 Note that it uses the fact, that this function is called 1364 with locally disabled BH and that sk cannot be already spinlocked. 1365 */ 1366 bh_lock_sock(sk); 1367 inet->tos = skb->nh.iph->tos; 1368 sk->sk_priority = skb->priority; 1369 sk->sk_protocol = skb->nh.iph->protocol; 1370 ip_append_data(sk, ip_reply_glue_bits, arg->iov->iov_base, len, 0, 1371 &ipc, rt, MSG_DONTWAIT); 1372 if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) { 1373 if (arg->csumoffset >= 0) 1374 *((u16 *)skb->h.raw + arg->csumoffset) = csum_fold(csum_add(skb->csum, arg->csum)); 1375 skb->ip_summed = CHECKSUM_NONE; 1376 ip_push_pending_frames(sk); 1377 } 1378 1379 bh_unlock_sock(sk); 1380 1381 ip_rt_put(rt); 1382} 1383 1384void __init ip_init(void) 1385{ 1386 ip_rt_init(); 1387 inet_initpeers(); 1388 1389#if defined(CONFIG_IP_MULTICAST) && defined(CONFIG_PROC_FS) 1390 igmp_mc_proc_init(); 1391#endif 1392} 1393 1394EXPORT_SYMBOL(ip_fragment); 1395EXPORT_SYMBOL(ip_generic_getfrag); 1396EXPORT_SYMBOL(ip_queue_xmit); 1397EXPORT_SYMBOL(ip_send_check); 1398