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 * Implementation of the Transmission Control Protocol(TCP). 7 * 8 * IPv4 specific functions 9 * 10 * 11 * code split from: 12 * linux/ipv4/tcp.c 13 * linux/ipv4/tcp_input.c 14 * linux/ipv4/tcp_output.c 15 * 16 * See tcp.c for author information 17 * 18 * This program is free software; you can redistribute it and/or 19 * modify it under the terms of the GNU General Public License 20 * as published by the Free Software Foundation; either version 21 * 2 of the License, or (at your option) any later version. 22 */ 23 24 /* 25 * Changes: 26 * David S. Miller : New socket lookup architecture. 27 * This code is dedicated to John Dyson. 28 * David S. Miller : Change semantics of established hash, 29 * half is devoted to TIME_WAIT sockets 30 * and the rest go in the other half. 31 * Andi Kleen : Add support for syncookies and fixed 32 * some bugs: ip options weren't passed to 33 * the TCP layer, missed a check for an 34 * ACK bit. 35 * Andi Kleen : Implemented fast path mtu discovery. 36 * Fixed many serious bugs in the 37 * request_sock handling and moved 38 * most of it into the af independent code. 39 * Added tail drop and some other bugfixes. 40 * Added new listen semantics. 41 * Mike McLagan : Routing by source 42 * Juan Jose Ciarlante: ip_dynaddr bits 43 * Andi Kleen: various fixes. 44 * Vitaly E. Lavrov : Transparent proxy revived after year 45 * coma. 46 * Andi Kleen : Fix new listen. 47 * Andi Kleen : Fix accept error reporting. 48 * YOSHIFUJI Hideaki @USAGI and: Support IPV6_V6ONLY socket option, which 49 * Alexey Kuznetsov allow both IPv4 and IPv6 sockets to bind 50 * a single port at the same time. 51 */ 52 53 54 #include <linux/bottom_half.h> 55 #include <linux/types.h> 56 #include <linux/fcntl.h> 57 #include <linux/module.h> 58 #include <linux/random.h> 59 #include <linux/cache.h> 60 #include <linux/jhash.h> 61 #include <linux/init.h> 62 #include <linux/times.h> 63 64 #include <net/net_namespace.h> 65 #include <net/icmp.h> 66 #include <net/inet_hashtables.h> 67 #include <net/tcp.h> 68 #include <net/transp_v6.h> 69 #include <net/ipv6.h> 70 #include <net/inet_common.h> 71 #include <net/timewait_sock.h> 72 #include <net/xfrm.h> 73 #include <net/netdma.h> 74 75 #include <linux/inet.h> 76 #include <linux/ipv6.h> 77 #include <linux/stddef.h> 78 #include <linux/proc_fs.h> 79 #include <linux/seq_file.h> 80 81 #include <linux/crypto.h> 82 #include <linux/scatterlist.h> 83 84 int sysctl_tcp_tw_reuse __read_mostly; 85 int sysctl_tcp_low_latency __read_mostly; 86 87 88 #ifdef CONFIG_TCP_MD5SIG 89 static struct tcp_md5sig_key *tcp_v4_md5_do_lookup(struct sock *sk, 90 __be32 addr); 91 static int tcp_v4_md5_hash_hdr(char *md5_hash, struct tcp_md5sig_key *key, 92 __be32 daddr, __be32 saddr, struct tcphdr *th); 93 #else 94 static inline 95 struct tcp_md5sig_key *tcp_v4_md5_do_lookup(struct sock *sk, __be32 addr) 96 { 97 return NULL; 98 } 99 #endif 100 101 struct inet_hashinfo tcp_hashinfo; 102 103 static inline __u32 tcp_v4_init_sequence(struct sk_buff *skb) 104 { 105 return secure_tcp_sequence_number(ip_hdr(skb)->daddr, 106 ip_hdr(skb)->saddr, 107 tcp_hdr(skb)->dest, 108 tcp_hdr(skb)->source); 109 } 110 111 int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp) 112 { 113 const struct tcp_timewait_sock *tcptw = tcp_twsk(sktw); 114 struct tcp_sock *tp = tcp_sk(sk); 115 116 /* With PAWS, it is safe from the viewpoint 117 of data integrity. Even without PAWS it is safe provided sequence 118 spaces do not overlap i.e. at data rates <= 80Mbit/sec. 119 120 Actually, the idea is close to VJ's one, only timestamp cache is 121 held not per host, but per port pair and TW bucket is used as state 122 holder. 123 124 If TW bucket has been already destroyed we fall back to VJ's scheme 125 and use initial timestamp retrieved from peer table. 126 */ 127 if (tcptw->tw_ts_recent_stamp && 128 (twp == NULL || (sysctl_tcp_tw_reuse && 129 get_seconds() - tcptw->tw_ts_recent_stamp > 1))) { 130 tp->write_seq = tcptw->tw_snd_nxt + 65535 + 2; 131 if (tp->write_seq == 0) 132 tp->write_seq = 1; 133 tp->rx_opt.ts_recent = tcptw->tw_ts_recent; 134 tp->rx_opt.ts_recent_stamp = tcptw->tw_ts_recent_stamp; 135 sock_hold(sktw); 136 return 1; 137 } 138 139 return 0; 140 } 141 142 EXPORT_SYMBOL_GPL(tcp_twsk_unique); 143 144 /* This will initiate an outgoing connection. */ 145 int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len) 146 { 147 struct inet_sock *inet = inet_sk(sk); 148 struct tcp_sock *tp = tcp_sk(sk); 149 struct sockaddr_in *usin = (struct sockaddr_in *)uaddr; 150 struct rtable *rt; 151 __be32 daddr, nexthop; 152 int tmp; 153 int err; 154 155 if (addr_len < sizeof(struct sockaddr_in)) 156 return -EINVAL; 157 158 if (usin->sin_family != AF_INET) 159 return -EAFNOSUPPORT; 160 161 nexthop = daddr = usin->sin_addr.s_addr; 162 if (inet->opt && inet->opt->srr) { 163 if (!daddr) 164 return -EINVAL; 165 nexthop = inet->opt->faddr; 166 } 167 168 tmp = ip_route_connect(&rt, nexthop, inet->saddr, 169 RT_CONN_FLAGS(sk), sk->sk_bound_dev_if, 170 IPPROTO_TCP, 171 inet->sport, usin->sin_port, sk, 1); 172 if (tmp < 0) { 173 if (tmp == -ENETUNREACH) 174 IP_INC_STATS_BH(sock_net(sk), IPSTATS_MIB_OUTNOROUTES); 175 return tmp; 176 } 177 178 if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) { 179 ip_rt_put(rt); 180 return -ENETUNREACH; 181 } 182 183 if (!inet->opt || !inet->opt->srr) 184 daddr = rt->rt_dst; 185 186 if (!inet->saddr) 187 inet->saddr = rt->rt_src; 188 inet->rcv_saddr = inet->saddr; 189 190 if (tp->rx_opt.ts_recent_stamp && inet->daddr != daddr) { 191 /* Reset inherited state */ 192 tp->rx_opt.ts_recent = 0; 193 tp->rx_opt.ts_recent_stamp = 0; 194 tp->write_seq = 0; 195 } 196 197 if (tcp_death_row.sysctl_tw_recycle && 198 !tp->rx_opt.ts_recent_stamp && rt->rt_dst == daddr) { 199 struct inet_peer *peer = rt_get_peer(rt); 200 /* 201 * VJ's idea. We save last timestamp seen from 202 * the destination in peer table, when entering state 203 * TIME-WAIT * and initialize rx_opt.ts_recent from it, 204 * when trying new connection. 205 */ 206 if (peer != NULL && 207 peer->tcp_ts_stamp + TCP_PAWS_MSL >= get_seconds()) { 208 tp->rx_opt.ts_recent_stamp = peer->tcp_ts_stamp; 209 tp->rx_opt.ts_recent = peer->tcp_ts; 210 } 211 } 212 213 inet->dport = usin->sin_port; 214 inet->daddr = daddr; 215 216 inet_csk(sk)->icsk_ext_hdr_len = 0; 217 if (inet->opt) 218 inet_csk(sk)->icsk_ext_hdr_len = inet->opt->optlen; 219 220 tp->rx_opt.mss_clamp = 536; 221 222 /* Socket identity is still unknown (sport may be zero). 223 * However we set state to SYN-SENT and not releasing socket 224 * lock select source port, enter ourselves into the hash tables and 225 * complete initialization after this. 226 */ 227 tcp_set_state(sk, TCP_SYN_SENT); 228 err = inet_hash_connect(&tcp_death_row, sk); 229 if (err) 230 goto failure; 231 232 err = ip_route_newports(&rt, IPPROTO_TCP, 233 inet->sport, inet->dport, sk); 234 if (err) 235 goto failure; 236 237 /* OK, now commit destination to socket. */ 238 sk->sk_gso_type = SKB_GSO_TCPV4; 239 sk_setup_caps(sk, &rt->u.dst); 240 241 if (!tp->write_seq) 242 tp->write_seq = secure_tcp_sequence_number(inet->saddr, 243 inet->daddr, 244 inet->sport, 245 usin->sin_port); 246 247 inet->id = tp->write_seq ^ jiffies; 248 249 err = tcp_connect(sk); 250 rt = NULL; 251 if (err) 252 goto failure; 253 254 return 0; 255 256 failure: 257 /* 258 * This unhashes the socket and releases the local port, 259 * if necessary. 260 */ 261 tcp_set_state(sk, TCP_CLOSE); 262 ip_rt_put(rt); 263 sk->sk_route_caps = 0; 264 inet->dport = 0; 265 return err; 266 } 267 268 /* 269 * This routine does path mtu discovery as defined in RFC1191. 270 */ 271 static void do_pmtu_discovery(struct sock *sk, struct iphdr *iph, u32 mtu) 272 { 273 struct dst_entry *dst; 274 struct inet_sock *inet = inet_sk(sk); 275 276 /* We are not interested in TCP_LISTEN and open_requests (SYN-ACKs 277 * send out by Linux are always <576bytes so they should go through 278 * unfragmented). 279 */ 280 if (sk->sk_state == TCP_LISTEN) 281 return; 282 283 /* We don't check in the destentry if pmtu discovery is forbidden 284 * on this route. We just assume that no packet_to_big packets 285 * are send back when pmtu discovery is not active. 286 * There is a small race when the user changes this flag in the 287 * route, but I think that's acceptable. 288 */ 289 if ((dst = __sk_dst_check(sk, 0)) == NULL) 290 return; 291 292 dst->ops->update_pmtu(dst, mtu); 293 294 /* Something is about to be wrong... Remember soft error 295 * for the case, if this connection will not able to recover. 296 */ 297 if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst)) 298 sk->sk_err_soft = EMSGSIZE; 299 300 mtu = dst_mtu(dst); 301 302 if (inet->pmtudisc != IP_PMTUDISC_DONT && 303 inet_csk(sk)->icsk_pmtu_cookie > mtu) { 304 tcp_sync_mss(sk, mtu); 305 306 /* Resend the TCP packet because it's 307 * clear that the old packet has been 308 * dropped. This is the new "fast" path mtu 309 * discovery. 310 */ 311 tcp_simple_retransmit(sk); 312 } /* else let the usual retransmit timer handle it */ 313 } 314 315 /* 316 * This routine is called by the ICMP module when it gets some 317 * sort of error condition. If err < 0 then the socket should 318 * be closed and the error returned to the user. If err > 0 319 * it's just the icmp type << 8 | icmp code. After adjustment 320 * header points to the first 8 bytes of the tcp header. We need 321 * to find the appropriate port. 322 * 323 * The locking strategy used here is very "optimistic". When 324 * someone else accesses the socket the ICMP is just dropped 325 * and for some paths there is no check at all. 326 * A more general error queue to queue errors for later handling 327 * is probably better. 328 * 329 */ 330 331 void tcp_v4_err(struct sk_buff *skb, u32 info) 332 { 333 struct iphdr *iph = (struct iphdr *)skb->data; 334 struct tcphdr *th = (struct tcphdr *)(skb->data + (iph->ihl << 2)); 335 struct tcp_sock *tp; 336 struct inet_sock *inet; 337 const int type = icmp_hdr(skb)->type; 338 const int code = icmp_hdr(skb)->code; 339 struct sock *sk; 340 __u32 seq; 341 int err; 342 struct net *net = dev_net(skb->dev); 343 344 if (skb->len < (iph->ihl << 2) + 8) { 345 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS); 346 return; 347 } 348 349 sk = inet_lookup(net, &tcp_hashinfo, iph->daddr, th->dest, 350 iph->saddr, th->source, inet_iif(skb)); 351 if (!sk) { 352 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS); 353 return; 354 } 355 if (sk->sk_state == TCP_TIME_WAIT) { 356 inet_twsk_put(inet_twsk(sk)); 357 return; 358 } 359 360 bh_lock_sock(sk); 361 /* If too many ICMPs get dropped on busy 362 * servers this needs to be solved differently. 363 */ 364 if (sock_owned_by_user(sk)) 365 NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS); 366 367 if (sk->sk_state == TCP_CLOSE) 368 goto out; 369 370 tp = tcp_sk(sk); 371 seq = ntohl(th->seq); 372 if (sk->sk_state != TCP_LISTEN && 373 !between(seq, tp->snd_una, tp->snd_nxt)) { 374 NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS); 375 goto out; 376 } 377 378 switch (type) { 379 case ICMP_SOURCE_QUENCH: 380 /* Just silently ignore these. */ 381 goto out; 382 case ICMP_PARAMETERPROB: 383 err = EPROTO; 384 break; 385 case ICMP_DEST_UNREACH: 386 if (code > NR_ICMP_UNREACH) 387 goto out; 388 389 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */ 390 if (!sock_owned_by_user(sk)) 391 do_pmtu_discovery(sk, iph, info); 392 goto out; 393 } 394 395 err = icmp_err_convert[code].errno; 396 break; 397 case ICMP_TIME_EXCEEDED: 398 err = EHOSTUNREACH; 399 break; 400 default: 401 goto out; 402 } 403 404 switch (sk->sk_state) { 405 struct request_sock *req, **prev; 406 case TCP_LISTEN: 407 if (sock_owned_by_user(sk)) 408 goto out; 409 410 req = inet_csk_search_req(sk, &prev, th->dest, 411 iph->daddr, iph->saddr); 412 if (!req) 413 goto out; 414 415 /* ICMPs are not backlogged, hence we cannot get 416 an established socket here. 417 */ 418 WARN_ON(req->sk); 419 420 if (seq != tcp_rsk(req)->snt_isn) { 421 NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS); 422 goto out; 423 } 424 425 /* 426 * Still in SYN_RECV, just remove it silently. 427 * There is no good way to pass the error to the newly 428 * created socket, and POSIX does not want network 429 * errors returned from accept(). 430 */ 431 inet_csk_reqsk_queue_drop(sk, req, prev); 432 goto out; 433 434 case TCP_SYN_SENT: 435 case TCP_SYN_RECV: /* Cannot happen. 436 It can f.e. if SYNs crossed. 437 */ 438 if (!sock_owned_by_user(sk)) { 439 sk->sk_err = err; 440 441 sk->sk_error_report(sk); 442 443 tcp_done(sk); 444 } else { 445 sk->sk_err_soft = err; 446 } 447 goto out; 448 } 449 450 /* If we've already connected we will keep trying 451 * until we time out, or the user gives up. 452 * 453 * rfc1122 4.2.3.9 allows to consider as hard errors 454 * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too, 455 * but it is obsoleted by pmtu discovery). 456 * 457 * Note, that in modern internet, where routing is unreliable 458 * and in each dark corner broken firewalls sit, sending random 459 * errors ordered by their masters even this two messages finally lose 460 * their original sense (even Linux sends invalid PORT_UNREACHs) 461 * 462 * Now we are in compliance with RFCs. 463 * --ANK (980905) 464 */ 465 466 inet = inet_sk(sk); 467 if (!sock_owned_by_user(sk) && inet->recverr) { 468 sk->sk_err = err; 469 sk->sk_error_report(sk); 470 } else { /* Only an error on timeout */ 471 sk->sk_err_soft = err; 472 } 473 474 out: 475 bh_unlock_sock(sk); 476 sock_put(sk); 477 } 478 479 /* This routine computes an IPv4 TCP checksum. */ 480 void tcp_v4_send_check(struct sock *sk, int len, struct sk_buff *skb) 481 { 482 struct inet_sock *inet = inet_sk(sk); 483 struct tcphdr *th = tcp_hdr(skb); 484 485 if (skb->ip_summed == CHECKSUM_PARTIAL) { 486 th->check = ~tcp_v4_check(len, inet->saddr, 487 inet->daddr, 0); 488 skb->csum_start = skb_transport_header(skb) - skb->head; 489 skb->csum_offset = offsetof(struct tcphdr, check); 490 } else { 491 th->check = tcp_v4_check(len, inet->saddr, inet->daddr, 492 csum_partial(th, 493 th->doff << 2, 494 skb->csum)); 495 } 496 } 497 498 int tcp_v4_gso_send_check(struct sk_buff *skb) 499 { 500 const struct iphdr *iph; 501 struct tcphdr *th; 502 503 if (!pskb_may_pull(skb, sizeof(*th))) 504 return -EINVAL; 505 506 iph = ip_hdr(skb); 507 th = tcp_hdr(skb); 508 509 th->check = 0; 510 th->check = ~tcp_v4_check(skb->len, iph->saddr, iph->daddr, 0); 511 skb->csum_start = skb_transport_header(skb) - skb->head; 512 skb->csum_offset = offsetof(struct tcphdr, check); 513 skb->ip_summed = CHECKSUM_PARTIAL; 514 return 0; 515 } 516 517 /* 518 * This routine will send an RST to the other tcp. 519 * 520 * Someone asks: why I NEVER use socket parameters (TOS, TTL etc.) 521 * for reset. 522 * Answer: if a packet caused RST, it is not for a socket 523 * existing in our system, if it is matched to a socket, 524 * it is just duplicate segment or bug in other side's TCP. 525 * So that we build reply only basing on parameters 526 * arrived with segment. 527 * Exception: precedence violation. We do not implement it in any case. 528 */ 529 530 static void tcp_v4_send_reset(struct sock *sk, struct sk_buff *skb) 531 { 532 struct tcphdr *th = tcp_hdr(skb); 533 struct { 534 struct tcphdr th; 535 #ifdef CONFIG_TCP_MD5SIG 536 __be32 opt[(TCPOLEN_MD5SIG_ALIGNED >> 2)]; 537 #endif 538 } rep; 539 struct ip_reply_arg arg; 540 #ifdef CONFIG_TCP_MD5SIG 541 struct tcp_md5sig_key *key; 542 #endif 543 struct net *net; 544 545 /* Never send a reset in response to a reset. */ 546 if (th->rst) 547 return; 548 549 if (skb->rtable->rt_type != RTN_LOCAL) 550 return; 551 552 /* Swap the send and the receive. */ 553 memset(&rep, 0, sizeof(rep)); 554 rep.th.dest = th->source; 555 rep.th.source = th->dest; 556 rep.th.doff = sizeof(struct tcphdr) / 4; 557 rep.th.rst = 1; 558 559 if (th->ack) { 560 rep.th.seq = th->ack_seq; 561 } else { 562 rep.th.ack = 1; 563 rep.th.ack_seq = htonl(ntohl(th->seq) + th->syn + th->fin + 564 skb->len - (th->doff << 2)); 565 } 566 567 memset(&arg, 0, sizeof(arg)); 568 arg.iov[0].iov_base = (unsigned char *)&rep; 569 arg.iov[0].iov_len = sizeof(rep.th); 570 571 #ifdef CONFIG_TCP_MD5SIG 572 key = sk ? tcp_v4_md5_do_lookup(sk, ip_hdr(skb)->daddr) : NULL; 573 if (key) { 574 rep.opt[0] = htonl((TCPOPT_NOP << 24) | 575 (TCPOPT_NOP << 16) | 576 (TCPOPT_MD5SIG << 8) | 577 TCPOLEN_MD5SIG); 578 /* Update length and the length the header thinks exists */ 579 arg.iov[0].iov_len += TCPOLEN_MD5SIG_ALIGNED; 580 rep.th.doff = arg.iov[0].iov_len / 4; 581 582 tcp_v4_md5_hash_hdr((__u8 *) &rep.opt[1], 583 key, ip_hdr(skb)->saddr, 584 ip_hdr(skb)->daddr, &rep.th); 585 } 586 #endif 587 arg.csum = csum_tcpudp_nofold(ip_hdr(skb)->daddr, 588 ip_hdr(skb)->saddr, /* XXX */ 589 arg.iov[0].iov_len, IPPROTO_TCP, 0); 590 arg.csumoffset = offsetof(struct tcphdr, check) / 2; 591 arg.flags = (sk && inet_sk(sk)->transparent) ? IP_REPLY_ARG_NOSRCCHECK : 0; 592 593 net = dev_net(skb->dst->dev); 594 ip_send_reply(net->ipv4.tcp_sock, skb, 595 &arg, arg.iov[0].iov_len); 596 597 TCP_INC_STATS_BH(net, TCP_MIB_OUTSEGS); 598 TCP_INC_STATS_BH(net, TCP_MIB_OUTRSTS); 599 } 600 601 /* The code following below sending ACKs in SYN-RECV and TIME-WAIT states 602 outside socket context is ugly, certainly. What can I do? 603 */ 604 605 static void tcp_v4_send_ack(struct sk_buff *skb, u32 seq, u32 ack, 606 u32 win, u32 ts, int oif, 607 struct tcp_md5sig_key *key, 608 int reply_flags) 609 { 610 struct tcphdr *th = tcp_hdr(skb); 611 struct { 612 struct tcphdr th; 613 __be32 opt[(TCPOLEN_TSTAMP_ALIGNED >> 2) 614 #ifdef CONFIG_TCP_MD5SIG 615 + (TCPOLEN_MD5SIG_ALIGNED >> 2) 616 #endif 617 ]; 618 } rep; 619 struct ip_reply_arg arg; 620 struct net *net = dev_net(skb->dst->dev); 621 622 memset(&rep.th, 0, sizeof(struct tcphdr)); 623 memset(&arg, 0, sizeof(arg)); 624 625 arg.iov[0].iov_base = (unsigned char *)&rep; 626 arg.iov[0].iov_len = sizeof(rep.th); 627 if (ts) { 628 rep.opt[0] = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) | 629 (TCPOPT_TIMESTAMP << 8) | 630 TCPOLEN_TIMESTAMP); 631 rep.opt[1] = htonl(tcp_time_stamp); 632 rep.opt[2] = htonl(ts); 633 arg.iov[0].iov_len += TCPOLEN_TSTAMP_ALIGNED; 634 } 635 636 /* Swap the send and the receive. */ 637 rep.th.dest = th->source; 638 rep.th.source = th->dest; 639 rep.th.doff = arg.iov[0].iov_len / 4; 640 rep.th.seq = htonl(seq); 641 rep.th.ack_seq = htonl(ack); 642 rep.th.ack = 1; 643 rep.th.window = htons(win); 644 645 #ifdef CONFIG_TCP_MD5SIG 646 if (key) { 647 int offset = (ts) ? 3 : 0; 648 649 rep.opt[offset++] = htonl((TCPOPT_NOP << 24) | 650 (TCPOPT_NOP << 16) | 651 (TCPOPT_MD5SIG << 8) | 652 TCPOLEN_MD5SIG); 653 arg.iov[0].iov_len += TCPOLEN_MD5SIG_ALIGNED; 654 rep.th.doff = arg.iov[0].iov_len/4; 655 656 tcp_v4_md5_hash_hdr((__u8 *) &rep.opt[offset], 657 key, ip_hdr(skb)->saddr, 658 ip_hdr(skb)->daddr, &rep.th); 659 } 660 #endif 661 arg.flags = reply_flags; 662 arg.csum = csum_tcpudp_nofold(ip_hdr(skb)->daddr, 663 ip_hdr(skb)->saddr, /* XXX */ 664 arg.iov[0].iov_len, IPPROTO_TCP, 0); 665 arg.csumoffset = offsetof(struct tcphdr, check) / 2; 666 if (oif) 667 arg.bound_dev_if = oif; 668 669 ip_send_reply(net->ipv4.tcp_sock, skb, 670 &arg, arg.iov[0].iov_len); 671 672 TCP_INC_STATS_BH(net, TCP_MIB_OUTSEGS); 673 } 674 675 static void tcp_v4_timewait_ack(struct sock *sk, struct sk_buff *skb) 676 { 677 struct inet_timewait_sock *tw = inet_twsk(sk); 678 struct tcp_timewait_sock *tcptw = tcp_twsk(sk); 679 680 tcp_v4_send_ack(skb, tcptw->tw_snd_nxt, tcptw->tw_rcv_nxt, 681 tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale, 682 tcptw->tw_ts_recent, 683 tw->tw_bound_dev_if, 684 tcp_twsk_md5_key(tcptw), 685 tw->tw_transparent ? IP_REPLY_ARG_NOSRCCHECK : 0 686 ); 687 688 inet_twsk_put(tw); 689 } 690 691 static void tcp_v4_reqsk_send_ack(struct sock *sk, struct sk_buff *skb, 692 struct request_sock *req) 693 { 694 tcp_v4_send_ack(skb, tcp_rsk(req)->snt_isn + 1, 695 tcp_rsk(req)->rcv_isn + 1, req->rcv_wnd, 696 req->ts_recent, 697 0, 698 tcp_v4_md5_do_lookup(sk, ip_hdr(skb)->daddr), 699 inet_rsk(req)->no_srccheck ? IP_REPLY_ARG_NOSRCCHECK : 0); 700 } 701 702 /* 703 * Send a SYN-ACK after having received a SYN. 704 * This still operates on a request_sock only, not on a big 705 * socket. 706 */ 707 static int __tcp_v4_send_synack(struct sock *sk, struct request_sock *req, 708 struct dst_entry *dst) 709 { 710 const struct inet_request_sock *ireq = inet_rsk(req); 711 int err = -1; 712 struct sk_buff * skb; 713 714 /* First, grab a route. */ 715 if (!dst && (dst = inet_csk_route_req(sk, req)) == NULL) 716 return -1; 717 718 skb = tcp_make_synack(sk, dst, req); 719 720 if (skb) { 721 struct tcphdr *th = tcp_hdr(skb); 722 723 th->check = tcp_v4_check(skb->len, 724 ireq->loc_addr, 725 ireq->rmt_addr, 726 csum_partial(th, skb->len, 727 skb->csum)); 728 729 err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr, 730 ireq->rmt_addr, 731 ireq->opt); 732 err = net_xmit_eval(err); 733 } 734 735 dst_release(dst); 736 return err; 737 } 738 739 static int tcp_v4_send_synack(struct sock *sk, struct request_sock *req) 740 { 741 return __tcp_v4_send_synack(sk, req, NULL); 742 } 743 744 /* 745 * IPv4 request_sock destructor. 746 */ 747 static void tcp_v4_reqsk_destructor(struct request_sock *req) 748 { 749 kfree(inet_rsk(req)->opt); 750 } 751 752 #ifdef CONFIG_SYN_COOKIES 753 static void syn_flood_warning(struct sk_buff *skb) 754 { 755 static unsigned long warntime; 756 757 if (time_after(jiffies, (warntime + HZ * 60))) { 758 warntime = jiffies; 759 printk(KERN_INFO 760 "possible SYN flooding on port %d. Sending cookies.\n", 761 ntohs(tcp_hdr(skb)->dest)); 762 } 763 } 764 #endif 765 766 /* 767 * Save and compile IPv4 options into the request_sock if needed. 768 */ 769 static struct ip_options *tcp_v4_save_options(struct sock *sk, 770 struct sk_buff *skb) 771 { 772 struct ip_options *opt = &(IPCB(skb)->opt); 773 struct ip_options *dopt = NULL; 774 775 if (opt && opt->optlen) { 776 int opt_size = optlength(opt); 777 dopt = kmalloc(opt_size, GFP_ATOMIC); 778 if (dopt) { 779 if (ip_options_echo(dopt, skb)) { 780 kfree(dopt); 781 dopt = NULL; 782 } 783 } 784 } 785 return dopt; 786 } 787 788 #ifdef CONFIG_TCP_MD5SIG 789 /* 790 * RFC2385 MD5 checksumming requires a mapping of 791 * IP address->MD5 Key. 792 * We need to maintain these in the sk structure. 793 */ 794 795 /* Find the Key structure for an address. */ 796 static struct tcp_md5sig_key * 797 tcp_v4_md5_do_lookup(struct sock *sk, __be32 addr) 798 { 799 struct tcp_sock *tp = tcp_sk(sk); 800 int i; 801 802 if (!tp->md5sig_info || !tp->md5sig_info->entries4) 803 return NULL; 804 for (i = 0; i < tp->md5sig_info->entries4; i++) { 805 if (tp->md5sig_info->keys4[i].addr == addr) 806 return &tp->md5sig_info->keys4[i].base; 807 } 808 return NULL; 809 } 810 811 struct tcp_md5sig_key *tcp_v4_md5_lookup(struct sock *sk, 812 struct sock *addr_sk) 813 { 814 return tcp_v4_md5_do_lookup(sk, inet_sk(addr_sk)->daddr); 815 } 816 817 EXPORT_SYMBOL(tcp_v4_md5_lookup); 818 819 static struct tcp_md5sig_key *tcp_v4_reqsk_md5_lookup(struct sock *sk, 820 struct request_sock *req) 821 { 822 return tcp_v4_md5_do_lookup(sk, inet_rsk(req)->rmt_addr); 823 } 824 825 /* This can be called on a newly created socket, from other files */ 826 int tcp_v4_md5_do_add(struct sock *sk, __be32 addr, 827 u8 *newkey, u8 newkeylen) 828 { 829 /* Add Key to the list */ 830 struct tcp_md5sig_key *key; 831 struct tcp_sock *tp = tcp_sk(sk); 832 struct tcp4_md5sig_key *keys; 833 834 key = tcp_v4_md5_do_lookup(sk, addr); 835 if (key) { 836 /* Pre-existing entry - just update that one. */ 837 kfree(key->key); 838 key->key = newkey; 839 key->keylen = newkeylen; 840 } else { 841 struct tcp_md5sig_info *md5sig; 842 843 if (!tp->md5sig_info) { 844 tp->md5sig_info = kzalloc(sizeof(*tp->md5sig_info), 845 GFP_ATOMIC); 846 if (!tp->md5sig_info) { 847 kfree(newkey); 848 return -ENOMEM; 849 } 850 sk->sk_route_caps &= ~NETIF_F_GSO_MASK; 851 } 852 if (tcp_alloc_md5sig_pool() == NULL) { 853 kfree(newkey); 854 return -ENOMEM; 855 } 856 md5sig = tp->md5sig_info; 857 858 if (md5sig->alloced4 == md5sig->entries4) { 859 keys = kmalloc((sizeof(*keys) * 860 (md5sig->entries4 + 1)), GFP_ATOMIC); 861 if (!keys) { 862 kfree(newkey); 863 tcp_free_md5sig_pool(); 864 return -ENOMEM; 865 } 866 867 if (md5sig->entries4) 868 memcpy(keys, md5sig->keys4, 869 sizeof(*keys) * md5sig->entries4); 870 871 /* Free old key list, and reference new one */ 872 kfree(md5sig->keys4); 873 md5sig->keys4 = keys; 874 md5sig->alloced4++; 875 } 876 md5sig->entries4++; 877 md5sig->keys4[md5sig->entries4 - 1].addr = addr; 878 md5sig->keys4[md5sig->entries4 - 1].base.key = newkey; 879 md5sig->keys4[md5sig->entries4 - 1].base.keylen = newkeylen; 880 } 881 return 0; 882 } 883 884 EXPORT_SYMBOL(tcp_v4_md5_do_add); 885 886 static int tcp_v4_md5_add_func(struct sock *sk, struct sock *addr_sk, 887 u8 *newkey, u8 newkeylen) 888 { 889 return tcp_v4_md5_do_add(sk, inet_sk(addr_sk)->daddr, 890 newkey, newkeylen); 891 } 892 893 int tcp_v4_md5_do_del(struct sock *sk, __be32 addr) 894 { 895 struct tcp_sock *tp = tcp_sk(sk); 896 int i; 897 898 for (i = 0; i < tp->md5sig_info->entries4; i++) { 899 if (tp->md5sig_info->keys4[i].addr == addr) { 900 /* Free the key */ 901 kfree(tp->md5sig_info->keys4[i].base.key); 902 tp->md5sig_info->entries4--; 903 904 if (tp->md5sig_info->entries4 == 0) { 905 kfree(tp->md5sig_info->keys4); 906 tp->md5sig_info->keys4 = NULL; 907 tp->md5sig_info->alloced4 = 0; 908 } else if (tp->md5sig_info->entries4 != i) { 909 /* Need to do some manipulation */ 910 memmove(&tp->md5sig_info->keys4[i], 911 &tp->md5sig_info->keys4[i+1], 912 (tp->md5sig_info->entries4 - i) * 913 sizeof(struct tcp4_md5sig_key)); 914 } 915 tcp_free_md5sig_pool(); 916 return 0; 917 } 918 } 919 return -ENOENT; 920 } 921 922 EXPORT_SYMBOL(tcp_v4_md5_do_del); 923 924 static void tcp_v4_clear_md5_list(struct sock *sk) 925 { 926 struct tcp_sock *tp = tcp_sk(sk); 927 928 /* Free each key, then the set of key keys, 929 * the crypto element, and then decrement our 930 * hold on the last resort crypto. 931 */ 932 if (tp->md5sig_info->entries4) { 933 int i; 934 for (i = 0; i < tp->md5sig_info->entries4; i++) 935 kfree(tp->md5sig_info->keys4[i].base.key); 936 tp->md5sig_info->entries4 = 0; 937 tcp_free_md5sig_pool(); 938 } 939 if (tp->md5sig_info->keys4) { 940 kfree(tp->md5sig_info->keys4); 941 tp->md5sig_info->keys4 = NULL; 942 tp->md5sig_info->alloced4 = 0; 943 } 944 } 945 946 static int tcp_v4_parse_md5_keys(struct sock *sk, char __user *optval, 947 int optlen) 948 { 949 struct tcp_md5sig cmd; 950 struct sockaddr_in *sin = (struct sockaddr_in *)&cmd.tcpm_addr; 951 u8 *newkey; 952 953 if (optlen < sizeof(cmd)) 954 return -EINVAL; 955 956 if (copy_from_user(&cmd, optval, sizeof(cmd))) 957 return -EFAULT; 958 959 if (sin->sin_family != AF_INET) 960 return -EINVAL; 961 962 if (!cmd.tcpm_key || !cmd.tcpm_keylen) { 963 if (!tcp_sk(sk)->md5sig_info) 964 return -ENOENT; 965 return tcp_v4_md5_do_del(sk, sin->sin_addr.s_addr); 966 } 967 968 if (cmd.tcpm_keylen > TCP_MD5SIG_MAXKEYLEN) 969 return -EINVAL; 970 971 if (!tcp_sk(sk)->md5sig_info) { 972 struct tcp_sock *tp = tcp_sk(sk); 973 struct tcp_md5sig_info *p = kzalloc(sizeof(*p), GFP_KERNEL); 974 975 if (!p) 976 return -EINVAL; 977 978 tp->md5sig_info = p; 979 sk->sk_route_caps &= ~NETIF_F_GSO_MASK; 980 } 981 982 newkey = kmemdup(cmd.tcpm_key, cmd.tcpm_keylen, GFP_KERNEL); 983 if (!newkey) 984 return -ENOMEM; 985 return tcp_v4_md5_do_add(sk, sin->sin_addr.s_addr, 986 newkey, cmd.tcpm_keylen); 987 } 988 989 static int tcp_v4_md5_hash_pseudoheader(struct tcp_md5sig_pool *hp, 990 __be32 daddr, __be32 saddr, int nbytes) 991 { 992 struct tcp4_pseudohdr *bp; 993 struct scatterlist sg; 994 995 bp = &hp->md5_blk.ip4; 996 997 /* 998 * 1. the TCP pseudo-header (in the order: source IP address, 999 * destination IP address, zero-padded protocol number, and 1000 * segment length) 1001 */ 1002 bp->saddr = saddr; 1003 bp->daddr = daddr; 1004 bp->pad = 0; 1005 bp->protocol = IPPROTO_TCP; 1006 bp->len = cpu_to_be16(nbytes); 1007 1008 sg_init_one(&sg, bp, sizeof(*bp)); 1009 return crypto_hash_update(&hp->md5_desc, &sg, sizeof(*bp)); 1010 } 1011 1012 static int tcp_v4_md5_hash_hdr(char *md5_hash, struct tcp_md5sig_key *key, 1013 __be32 daddr, __be32 saddr, struct tcphdr *th) 1014 { 1015 struct tcp_md5sig_pool *hp; 1016 struct hash_desc *desc; 1017 1018 hp = tcp_get_md5sig_pool(); 1019 if (!hp) 1020 goto clear_hash_noput; 1021 desc = &hp->md5_desc; 1022 1023 if (crypto_hash_init(desc)) 1024 goto clear_hash; 1025 if (tcp_v4_md5_hash_pseudoheader(hp, daddr, saddr, th->doff << 2)) 1026 goto clear_hash; 1027 if (tcp_md5_hash_header(hp, th)) 1028 goto clear_hash; 1029 if (tcp_md5_hash_key(hp, key)) 1030 goto clear_hash; 1031 if (crypto_hash_final(desc, md5_hash)) 1032 goto clear_hash; 1033 1034 tcp_put_md5sig_pool(); 1035 return 0; 1036 1037 clear_hash: 1038 tcp_put_md5sig_pool(); 1039 clear_hash_noput: 1040 memset(md5_hash, 0, 16); 1041 return 1; 1042 } 1043 1044 int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key, 1045 struct sock *sk, struct request_sock *req, 1046 struct sk_buff *skb) 1047 { 1048 struct tcp_md5sig_pool *hp; 1049 struct hash_desc *desc; 1050 struct tcphdr *th = tcp_hdr(skb); 1051 __be32 saddr, daddr; 1052 1053 if (sk) { 1054 saddr = inet_sk(sk)->saddr; 1055 daddr = inet_sk(sk)->daddr; 1056 } else if (req) { 1057 saddr = inet_rsk(req)->loc_addr; 1058 daddr = inet_rsk(req)->rmt_addr; 1059 } else { 1060 const struct iphdr *iph = ip_hdr(skb); 1061 saddr = iph->saddr; 1062 daddr = iph->daddr; 1063 } 1064 1065 hp = tcp_get_md5sig_pool(); 1066 if (!hp) 1067 goto clear_hash_noput; 1068 desc = &hp->md5_desc; 1069 1070 if (crypto_hash_init(desc)) 1071 goto clear_hash; 1072 1073 if (tcp_v4_md5_hash_pseudoheader(hp, daddr, saddr, skb->len)) 1074 goto clear_hash; 1075 if (tcp_md5_hash_header(hp, th)) 1076 goto clear_hash; 1077 if (tcp_md5_hash_skb_data(hp, skb, th->doff << 2)) 1078 goto clear_hash; 1079 if (tcp_md5_hash_key(hp, key)) 1080 goto clear_hash; 1081 if (crypto_hash_final(desc, md5_hash)) 1082 goto clear_hash; 1083 1084 tcp_put_md5sig_pool(); 1085 return 0; 1086 1087 clear_hash: 1088 tcp_put_md5sig_pool(); 1089 clear_hash_noput: 1090 memset(md5_hash, 0, 16); 1091 return 1; 1092 } 1093 1094 EXPORT_SYMBOL(tcp_v4_md5_hash_skb); 1095 1096 static int tcp_v4_inbound_md5_hash(struct sock *sk, struct sk_buff *skb) 1097 { 1098 /* 1099 * This gets called for each TCP segment that arrives 1100 * so we want to be efficient. 1101 * We have 3 drop cases: 1102 * o No MD5 hash and one expected. 1103 * o MD5 hash and we're not expecting one. 1104 * o MD5 hash and its wrong. 1105 */ 1106 __u8 *hash_location = NULL; 1107 struct tcp_md5sig_key *hash_expected; 1108 const struct iphdr *iph = ip_hdr(skb); 1109 struct tcphdr *th = tcp_hdr(skb); 1110 int genhash; 1111 unsigned char newhash[16]; 1112 1113 hash_expected = tcp_v4_md5_do_lookup(sk, iph->saddr); 1114 hash_location = tcp_parse_md5sig_option(th); 1115 1116 /* We've parsed the options - do we have a hash? */ 1117 if (!hash_expected && !hash_location) 1118 return 0; 1119 1120 if (hash_expected && !hash_location) { 1121 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPMD5NOTFOUND); 1122 return 1; 1123 } 1124 1125 if (!hash_expected && hash_location) { 1126 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPMD5UNEXPECTED); 1127 return 1; 1128 } 1129 1130 /* Okay, so this is hash_expected and hash_location - 1131 * so we need to calculate the checksum. 1132 */ 1133 genhash = tcp_v4_md5_hash_skb(newhash, 1134 hash_expected, 1135 NULL, NULL, skb); 1136 1137 if (genhash || memcmp(hash_location, newhash, 16) != 0) { 1138 if (net_ratelimit()) { 1139 printk(KERN_INFO "MD5 Hash failed for (%pI4, %d)->(%pI4, %d)%s\n", 1140 &iph->saddr, ntohs(th->source), 1141 &iph->daddr, ntohs(th->dest), 1142 genhash ? " tcp_v4_calc_md5_hash failed" : ""); 1143 } 1144 return 1; 1145 } 1146 return 0; 1147 } 1148 1149 #endif 1150 1151 struct request_sock_ops tcp_request_sock_ops __read_mostly = { 1152 .family = PF_INET, 1153 .obj_size = sizeof(struct tcp_request_sock), 1154 .rtx_syn_ack = tcp_v4_send_synack, 1155 .send_ack = tcp_v4_reqsk_send_ack, 1156 .destructor = tcp_v4_reqsk_destructor, 1157 .send_reset = tcp_v4_send_reset, 1158 }; 1159 1160 #ifdef CONFIG_TCP_MD5SIG 1161 static struct tcp_request_sock_ops tcp_request_sock_ipv4_ops = { 1162 .md5_lookup = tcp_v4_reqsk_md5_lookup, 1163 }; 1164 #endif 1165 1166 static struct timewait_sock_ops tcp_timewait_sock_ops = { 1167 .twsk_obj_size = sizeof(struct tcp_timewait_sock), 1168 .twsk_unique = tcp_twsk_unique, 1169 .twsk_destructor= tcp_twsk_destructor, 1170 }; 1171 1172 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb) 1173 { 1174 struct inet_request_sock *ireq; 1175 struct tcp_options_received tmp_opt; 1176 struct request_sock *req; 1177 __be32 saddr = ip_hdr(skb)->saddr; 1178 __be32 daddr = ip_hdr(skb)->daddr; 1179 __u32 isn = TCP_SKB_CB(skb)->when; 1180 struct dst_entry *dst = NULL; 1181 #ifdef CONFIG_SYN_COOKIES 1182 int want_cookie = 0; 1183 #else 1184 #define want_cookie 0 /* Argh, why doesn't gcc optimize this :( */ 1185 #endif 1186 1187 /* Never answer to SYNs send to broadcast or multicast */ 1188 if (skb->rtable->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 1189 goto drop; 1190 1191 /* TW buckets are converted to open requests without 1192 * limitations, they conserve resources and peer is 1193 * evidently real one. 1194 */ 1195 if (inet_csk_reqsk_queue_is_full(sk) && !isn) { 1196 #ifdef CONFIG_SYN_COOKIES 1197 if (sysctl_tcp_syncookies) { 1198 want_cookie = 1; 1199 } else 1200 #endif 1201 goto drop; 1202 } 1203 1204 /* Accept backlog is full. If we have already queued enough 1205 * of warm entries in syn queue, drop request. It is better than 1206 * clogging syn queue with openreqs with exponentially increasing 1207 * timeout. 1208 */ 1209 if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1) 1210 goto drop; 1211 1212 req = inet_reqsk_alloc(&tcp_request_sock_ops); 1213 if (!req) 1214 goto drop; 1215 1216 #ifdef CONFIG_TCP_MD5SIG 1217 tcp_rsk(req)->af_specific = &tcp_request_sock_ipv4_ops; 1218 #endif 1219 1220 tcp_clear_options(&tmp_opt); 1221 tmp_opt.mss_clamp = 536; 1222 tmp_opt.user_mss = tcp_sk(sk)->rx_opt.user_mss; 1223 1224 tcp_parse_options(skb, &tmp_opt, 0); 1225 1226 if (want_cookie && !tmp_opt.saw_tstamp) 1227 tcp_clear_options(&tmp_opt); 1228 1229 if (tmp_opt.saw_tstamp && !tmp_opt.rcv_tsval) { 1230 /* Some OSes (unknown ones, but I see them on web server, which 1231 * contains information interesting only for windows' 1232 * users) do not send their stamp in SYN. It is easy case. 1233 * We simply do not advertise TS support. 1234 */ 1235 tmp_opt.saw_tstamp = 0; 1236 tmp_opt.tstamp_ok = 0; 1237 } 1238 tmp_opt.tstamp_ok = tmp_opt.saw_tstamp; 1239 1240 tcp_openreq_init(req, &tmp_opt, skb); 1241 1242 if (security_inet_conn_request(sk, skb, req)) 1243 goto drop_and_free; 1244 1245 ireq = inet_rsk(req); 1246 ireq->loc_addr = daddr; 1247 ireq->rmt_addr = saddr; 1248 ireq->no_srccheck = inet_sk(sk)->transparent; 1249 ireq->opt = tcp_v4_save_options(sk, skb); 1250 if (!want_cookie) 1251 TCP_ECN_create_request(req, tcp_hdr(skb)); 1252 1253 if (want_cookie) { 1254 #ifdef CONFIG_SYN_COOKIES 1255 syn_flood_warning(skb); 1256 req->cookie_ts = tmp_opt.tstamp_ok; 1257 #endif 1258 isn = cookie_v4_init_sequence(sk, skb, &req->mss); 1259 } else if (!isn) { 1260 struct inet_peer *peer = NULL; 1261 1262 /* VJ's idea. We save last timestamp seen 1263 * from the destination in peer table, when entering 1264 * state TIME-WAIT, and check against it before 1265 * accepting new connection request. 1266 * 1267 * If "isn" is not zero, this request hit alive 1268 * timewait bucket, so that all the necessary checks 1269 * are made in the function processing timewait state. 1270 */ 1271 if (tmp_opt.saw_tstamp && 1272 tcp_death_row.sysctl_tw_recycle && 1273 (dst = inet_csk_route_req(sk, req)) != NULL && 1274 (peer = rt_get_peer((struct rtable *)dst)) != NULL && 1275 peer->v4daddr == saddr) { 1276 if (get_seconds() < peer->tcp_ts_stamp + TCP_PAWS_MSL && 1277 (s32)(peer->tcp_ts - req->ts_recent) > 1278 TCP_PAWS_WINDOW) { 1279 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_PAWSPASSIVEREJECTED); 1280 goto drop_and_release; 1281 } 1282 } 1283 /* Kill the following clause, if you dislike this way. */ 1284 else if (!sysctl_tcp_syncookies && 1285 (sysctl_max_syn_backlog - inet_csk_reqsk_queue_len(sk) < 1286 (sysctl_max_syn_backlog >> 2)) && 1287 (!peer || !peer->tcp_ts_stamp) && 1288 (!dst || !dst_metric(dst, RTAX_RTT))) { 1289 /* Without syncookies last quarter of 1290 * backlog is filled with destinations, 1291 * proven to be alive. 1292 * It means that we continue to communicate 1293 * to destinations, already remembered 1294 * to the moment of synflood. 1295 */ 1296 LIMIT_NETDEBUG(KERN_DEBUG "TCP: drop open request from %pI4/%u\n", 1297 &saddr, ntohs(tcp_hdr(skb)->source)); 1298 goto drop_and_release; 1299 } 1300 1301 isn = tcp_v4_init_sequence(skb); 1302 } 1303 tcp_rsk(req)->snt_isn = isn; 1304 1305 if (__tcp_v4_send_synack(sk, req, dst) || want_cookie) 1306 goto drop_and_free; 1307 1308 inet_csk_reqsk_queue_hash_add(sk, req, TCP_TIMEOUT_INIT); 1309 return 0; 1310 1311 drop_and_release: 1312 dst_release(dst); 1313 drop_and_free: 1314 reqsk_free(req); 1315 drop: 1316 return 0; 1317 } 1318 1319 1320 /* 1321 * The three way handshake has completed - we got a valid synack - 1322 * now create the new socket. 1323 */ 1324 struct sock *tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb, 1325 struct request_sock *req, 1326 struct dst_entry *dst) 1327 { 1328 struct inet_request_sock *ireq; 1329 struct inet_sock *newinet; 1330 struct tcp_sock *newtp; 1331 struct sock *newsk; 1332 #ifdef CONFIG_TCP_MD5SIG 1333 struct tcp_md5sig_key *key; 1334 #endif 1335 1336 if (sk_acceptq_is_full(sk)) 1337 goto exit_overflow; 1338 1339 if (!dst && (dst = inet_csk_route_req(sk, req)) == NULL) 1340 goto exit; 1341 1342 newsk = tcp_create_openreq_child(sk, req, skb); 1343 if (!newsk) 1344 goto exit; 1345 1346 newsk->sk_gso_type = SKB_GSO_TCPV4; 1347 sk_setup_caps(newsk, dst); 1348 1349 newtp = tcp_sk(newsk); 1350 newinet = inet_sk(newsk); 1351 ireq = inet_rsk(req); 1352 newinet->daddr = ireq->rmt_addr; 1353 newinet->rcv_saddr = ireq->loc_addr; 1354 newinet->saddr = ireq->loc_addr; 1355 newinet->opt = ireq->opt; 1356 ireq->opt = NULL; 1357 newinet->mc_index = inet_iif(skb); 1358 newinet->mc_ttl = ip_hdr(skb)->ttl; 1359 inet_csk(newsk)->icsk_ext_hdr_len = 0; 1360 if (newinet->opt) 1361 inet_csk(newsk)->icsk_ext_hdr_len = newinet->opt->optlen; 1362 newinet->id = newtp->write_seq ^ jiffies; 1363 1364 tcp_mtup_init(newsk); 1365 tcp_sync_mss(newsk, dst_mtu(dst)); 1366 newtp->advmss = dst_metric(dst, RTAX_ADVMSS); 1367 if (tcp_sk(sk)->rx_opt.user_mss && 1368 tcp_sk(sk)->rx_opt.user_mss < newtp->advmss) 1369 newtp->advmss = tcp_sk(sk)->rx_opt.user_mss; 1370 1371 tcp_initialize_rcv_mss(newsk); 1372 1373 #ifdef CONFIG_TCP_MD5SIG 1374 /* Copy over the MD5 key from the original socket */ 1375 if ((key = tcp_v4_md5_do_lookup(sk, newinet->daddr)) != NULL) { 1376 /* 1377 * We're using one, so create a matching key 1378 * on the newsk structure. If we fail to get 1379 * memory, then we end up not copying the key 1380 * across. Shucks. 1381 */ 1382 char *newkey = kmemdup(key->key, key->keylen, GFP_ATOMIC); 1383 if (newkey != NULL) 1384 tcp_v4_md5_do_add(newsk, inet_sk(sk)->daddr, 1385 newkey, key->keylen); 1386 newsk->sk_route_caps &= ~NETIF_F_GSO_MASK; 1387 } 1388 #endif 1389 1390 __inet_hash_nolisten(newsk); 1391 __inet_inherit_port(sk, newsk); 1392 1393 return newsk; 1394 1395 exit_overflow: 1396 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS); 1397 exit: 1398 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS); 1399 dst_release(dst); 1400 return NULL; 1401 } 1402 1403 static struct sock *tcp_v4_hnd_req(struct sock *sk, struct sk_buff *skb) 1404 { 1405 struct tcphdr *th = tcp_hdr(skb); 1406 const struct iphdr *iph = ip_hdr(skb); 1407 struct sock *nsk; 1408 struct request_sock **prev; 1409 /* Find possible connection requests. */ 1410 struct request_sock *req = inet_csk_search_req(sk, &prev, th->source, 1411 iph->saddr, iph->daddr); 1412 if (req) 1413 return tcp_check_req(sk, skb, req, prev); 1414 1415 nsk = inet_lookup_established(sock_net(sk), &tcp_hashinfo, iph->saddr, 1416 th->source, iph->daddr, th->dest, inet_iif(skb)); 1417 1418 if (nsk) { 1419 if (nsk->sk_state != TCP_TIME_WAIT) { 1420 bh_lock_sock(nsk); 1421 return nsk; 1422 } 1423 inet_twsk_put(inet_twsk(nsk)); 1424 return NULL; 1425 } 1426 1427 #ifdef CONFIG_SYN_COOKIES 1428 if (!th->rst && !th->syn && th->ack) 1429 sk = cookie_v4_check(sk, skb, &(IPCB(skb)->opt)); 1430 #endif 1431 return sk; 1432 } 1433 1434 static __sum16 tcp_v4_checksum_init(struct sk_buff *skb) 1435 { 1436 const struct iphdr *iph = ip_hdr(skb); 1437 1438 if (skb->ip_summed == CHECKSUM_COMPLETE) { 1439 if (!tcp_v4_check(skb->len, iph->saddr, 1440 iph->daddr, skb->csum)) { 1441 skb->ip_summed = CHECKSUM_UNNECESSARY; 1442 return 0; 1443 } 1444 } 1445 1446 skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr, 1447 skb->len, IPPROTO_TCP, 0); 1448 1449 if (skb->len <= 76) { 1450 return __skb_checksum_complete(skb); 1451 } 1452 return 0; 1453 } 1454 1455 1456 /* The socket must have it's spinlock held when we get 1457 * here. 1458 * 1459 * We have a potential double-lock case here, so even when 1460 * doing backlog processing we use the BH locking scheme. 1461 * This is because we cannot sleep with the original spinlock 1462 * held. 1463 */ 1464 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb) 1465 { 1466 struct sock *rsk; 1467 #ifdef CONFIG_TCP_MD5SIG 1468 /* 1469 * We really want to reject the packet as early as possible 1470 * if: 1471 * o We're expecting an MD5'd packet and this is no MD5 tcp option 1472 * o There is an MD5 option and we're not expecting one 1473 */ 1474 if (tcp_v4_inbound_md5_hash(sk, skb)) 1475 goto discard; 1476 #endif 1477 1478 if (sk->sk_state == TCP_ESTABLISHED) { /* Fast path */ 1479 TCP_CHECK_TIMER(sk); 1480 if (tcp_rcv_established(sk, skb, tcp_hdr(skb), skb->len)) { 1481 rsk = sk; 1482 goto reset; 1483 } 1484 TCP_CHECK_TIMER(sk); 1485 return 0; 1486 } 1487 1488 if (skb->len < tcp_hdrlen(skb) || tcp_checksum_complete(skb)) 1489 goto csum_err; 1490 1491 if (sk->sk_state == TCP_LISTEN) { 1492 struct sock *nsk = tcp_v4_hnd_req(sk, skb); 1493 if (!nsk) 1494 goto discard; 1495 1496 if (nsk != sk) { 1497 if (tcp_child_process(sk, nsk, skb)) { 1498 rsk = nsk; 1499 goto reset; 1500 } 1501 return 0; 1502 } 1503 } 1504 1505 TCP_CHECK_TIMER(sk); 1506 if (tcp_rcv_state_process(sk, skb, tcp_hdr(skb), skb->len)) { 1507 rsk = sk; 1508 goto reset; 1509 } 1510 TCP_CHECK_TIMER(sk); 1511 return 0; 1512 1513 reset: 1514 tcp_v4_send_reset(rsk, skb); 1515 discard: 1516 kfree_skb(skb); 1517 /* Be careful here. If this function gets more complicated and 1518 * gcc suffers from register pressure on the x86, sk (in %ebx) 1519 * might be destroyed here. This current version compiles correctly, 1520 * but you have been warned. 1521 */ 1522 return 0; 1523 1524 csum_err: 1525 TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_INERRS); 1526 goto discard; 1527 } 1528 1529 /* 1530 * From tcp_input.c 1531 */ 1532 1533 int tcp_v4_rcv(struct sk_buff *skb) 1534 { 1535 const struct iphdr *iph; 1536 struct tcphdr *th; 1537 struct sock *sk; 1538 int ret; 1539 struct net *net = dev_net(skb->dev); 1540 1541 if (skb->pkt_type != PACKET_HOST) 1542 goto discard_it; 1543 1544 /* Count it even if it's bad */ 1545 TCP_INC_STATS_BH(net, TCP_MIB_INSEGS); 1546 1547 if (!pskb_may_pull(skb, sizeof(struct tcphdr))) 1548 goto discard_it; 1549 1550 th = tcp_hdr(skb); 1551 1552 if (th->doff < sizeof(struct tcphdr) / 4) 1553 goto bad_packet; 1554 if (!pskb_may_pull(skb, th->doff * 4)) 1555 goto discard_it; 1556 1557 /* An explanation is required here, I think. 1558 * Packet length and doff are validated by header prediction, 1559 * provided case of th->doff==0 is eliminated. 1560 * So, we defer the checks. */ 1561 if (!skb_csum_unnecessary(skb) && tcp_v4_checksum_init(skb)) 1562 goto bad_packet; 1563 1564 th = tcp_hdr(skb); 1565 iph = ip_hdr(skb); 1566 TCP_SKB_CB(skb)->seq = ntohl(th->seq); 1567 TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin + 1568 skb->len - th->doff * 4); 1569 TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq); 1570 TCP_SKB_CB(skb)->when = 0; 1571 TCP_SKB_CB(skb)->flags = iph->tos; 1572 TCP_SKB_CB(skb)->sacked = 0; 1573 1574 sk = __inet_lookup_skb(&tcp_hashinfo, skb, th->source, th->dest); 1575 if (!sk) 1576 goto no_tcp_socket; 1577 1578 process: 1579 if (sk->sk_state == TCP_TIME_WAIT) 1580 goto do_time_wait; 1581 1582 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) 1583 goto discard_and_relse; 1584 nf_reset(skb); 1585 1586 if (sk_filter(sk, skb)) 1587 goto discard_and_relse; 1588 1589 skb->dev = NULL; 1590 1591 bh_lock_sock_nested(sk); 1592 ret = 0; 1593 if (!sock_owned_by_user(sk)) { 1594 #ifdef CONFIG_NET_DMA 1595 struct tcp_sock *tp = tcp_sk(sk); 1596 if (!tp->ucopy.dma_chan && tp->ucopy.pinned_list) 1597 tp->ucopy.dma_chan = dma_find_channel(DMA_MEMCPY); 1598 if (tp->ucopy.dma_chan) 1599 ret = tcp_v4_do_rcv(sk, skb); 1600 else 1601 #endif 1602 { 1603 if (!tcp_prequeue(sk, skb)) 1604 ret = tcp_v4_do_rcv(sk, skb); 1605 } 1606 } else 1607 sk_add_backlog(sk, skb); 1608 bh_unlock_sock(sk); 1609 1610 sock_put(sk); 1611 1612 return ret; 1613 1614 no_tcp_socket: 1615 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) 1616 goto discard_it; 1617 1618 if (skb->len < (th->doff << 2) || tcp_checksum_complete(skb)) { 1619 bad_packet: 1620 TCP_INC_STATS_BH(net, TCP_MIB_INERRS); 1621 } else { 1622 tcp_v4_send_reset(NULL, skb); 1623 } 1624 1625 discard_it: 1626 /* Discard frame. */ 1627 kfree_skb(skb); 1628 return 0; 1629 1630 discard_and_relse: 1631 sock_put(sk); 1632 goto discard_it; 1633 1634 do_time_wait: 1635 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { 1636 inet_twsk_put(inet_twsk(sk)); 1637 goto discard_it; 1638 } 1639 1640 if (skb->len < (th->doff << 2) || tcp_checksum_complete(skb)) { 1641 TCP_INC_STATS_BH(net, TCP_MIB_INERRS); 1642 inet_twsk_put(inet_twsk(sk)); 1643 goto discard_it; 1644 } 1645 switch (tcp_timewait_state_process(inet_twsk(sk), skb, th)) { 1646 case TCP_TW_SYN: { 1647 struct sock *sk2 = inet_lookup_listener(dev_net(skb->dev), 1648 &tcp_hashinfo, 1649 iph->daddr, th->dest, 1650 inet_iif(skb)); 1651 if (sk2) { 1652 inet_twsk_deschedule(inet_twsk(sk), &tcp_death_row); 1653 inet_twsk_put(inet_twsk(sk)); 1654 sk = sk2; 1655 goto process; 1656 } 1657 /* Fall through to ACK */ 1658 } 1659 case TCP_TW_ACK: 1660 tcp_v4_timewait_ack(sk, skb); 1661 break; 1662 case TCP_TW_RST: 1663 goto no_tcp_socket; 1664 case TCP_TW_SUCCESS:; 1665 } 1666 goto discard_it; 1667 } 1668 1669 /* VJ's idea. Save last timestamp seen from this destination 1670 * and hold it at least for normal timewait interval to use for duplicate 1671 * segment detection in subsequent connections, before they enter synchronized 1672 * state. 1673 */ 1674 1675 int tcp_v4_remember_stamp(struct sock *sk) 1676 { 1677 struct inet_sock *inet = inet_sk(sk); 1678 struct tcp_sock *tp = tcp_sk(sk); 1679 struct rtable *rt = (struct rtable *)__sk_dst_get(sk); 1680 struct inet_peer *peer = NULL; 1681 int release_it = 0; 1682 1683 if (!rt || rt->rt_dst != inet->daddr) { 1684 peer = inet_getpeer(inet->daddr, 1); 1685 release_it = 1; 1686 } else { 1687 if (!rt->peer) 1688 rt_bind_peer(rt, 1); 1689 peer = rt->peer; 1690 } 1691 1692 if (peer) { 1693 if ((s32)(peer->tcp_ts - tp->rx_opt.ts_recent) <= 0 || 1694 (peer->tcp_ts_stamp + TCP_PAWS_MSL < get_seconds() && 1695 peer->tcp_ts_stamp <= tp->rx_opt.ts_recent_stamp)) { 1696 peer->tcp_ts_stamp = tp->rx_opt.ts_recent_stamp; 1697 peer->tcp_ts = tp->rx_opt.ts_recent; 1698 } 1699 if (release_it) 1700 inet_putpeer(peer); 1701 return 1; 1702 } 1703 1704 return 0; 1705 } 1706 1707 int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw) 1708 { 1709 struct inet_peer *peer = inet_getpeer(tw->tw_daddr, 1); 1710 1711 if (peer) { 1712 const struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw); 1713 1714 if ((s32)(peer->tcp_ts - tcptw->tw_ts_recent) <= 0 || 1715 (peer->tcp_ts_stamp + TCP_PAWS_MSL < get_seconds() && 1716 peer->tcp_ts_stamp <= tcptw->tw_ts_recent_stamp)) { 1717 peer->tcp_ts_stamp = tcptw->tw_ts_recent_stamp; 1718 peer->tcp_ts = tcptw->tw_ts_recent; 1719 } 1720 inet_putpeer(peer); 1721 return 1; 1722 } 1723 1724 return 0; 1725 } 1726 1727 struct inet_connection_sock_af_ops ipv4_specific = { 1728 .queue_xmit = ip_queue_xmit, 1729 .send_check = tcp_v4_send_check, 1730 .rebuild_header = inet_sk_rebuild_header, 1731 .conn_request = tcp_v4_conn_request, 1732 .syn_recv_sock = tcp_v4_syn_recv_sock, 1733 .remember_stamp = tcp_v4_remember_stamp, 1734 .net_header_len = sizeof(struct iphdr), 1735 .setsockopt = ip_setsockopt, 1736 .getsockopt = ip_getsockopt, 1737 .addr2sockaddr = inet_csk_addr2sockaddr, 1738 .sockaddr_len = sizeof(struct sockaddr_in), 1739 .bind_conflict = inet_csk_bind_conflict, 1740 #ifdef CONFIG_COMPAT 1741 .compat_setsockopt = compat_ip_setsockopt, 1742 .compat_getsockopt = compat_ip_getsockopt, 1743 #endif 1744 }; 1745 1746 #ifdef CONFIG_TCP_MD5SIG 1747 static struct tcp_sock_af_ops tcp_sock_ipv4_specific = { 1748 .md5_lookup = tcp_v4_md5_lookup, 1749 .calc_md5_hash = tcp_v4_md5_hash_skb, 1750 .md5_add = tcp_v4_md5_add_func, 1751 .md5_parse = tcp_v4_parse_md5_keys, 1752 }; 1753 #endif 1754 1755 /* NOTE: A lot of things set to zero explicitly by call to 1756 * sk_alloc() so need not be done here. 1757 */ 1758 static int tcp_v4_init_sock(struct sock *sk) 1759 { 1760 struct inet_connection_sock *icsk = inet_csk(sk); 1761 struct tcp_sock *tp = tcp_sk(sk); 1762 1763 skb_queue_head_init(&tp->out_of_order_queue); 1764 tcp_init_xmit_timers(sk); 1765 tcp_prequeue_init(tp); 1766 1767 icsk->icsk_rto = TCP_TIMEOUT_INIT; 1768 tp->mdev = TCP_TIMEOUT_INIT; 1769 1770 /* So many TCP implementations out there (incorrectly) count the 1771 * initial SYN frame in their delayed-ACK and congestion control 1772 * algorithms that we must have the following bandaid to talk 1773 * efficiently to them. -DaveM 1774 */ 1775 tp->snd_cwnd = 2; 1776 1777 /* See draft-stevens-tcpca-spec-01 for discussion of the 1778 * initialization of these values. 1779 */ 1780 tp->snd_ssthresh = 0x7fffffff; /* Infinity */ 1781 tp->snd_cwnd_clamp = ~0; 1782 tp->mss_cache = 536; 1783 1784 tp->reordering = sysctl_tcp_reordering; 1785 icsk->icsk_ca_ops = &tcp_init_congestion_ops; 1786 1787 sk->sk_state = TCP_CLOSE; 1788 1789 sk->sk_write_space = sk_stream_write_space; 1790 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE); 1791 1792 icsk->icsk_af_ops = &ipv4_specific; 1793 icsk->icsk_sync_mss = tcp_sync_mss; 1794 #ifdef CONFIG_TCP_MD5SIG 1795 tp->af_specific = &tcp_sock_ipv4_specific; 1796 #endif 1797 1798 sk->sk_sndbuf = sysctl_tcp_wmem[1]; 1799 sk->sk_rcvbuf = sysctl_tcp_rmem[1]; 1800 1801 local_bh_disable(); 1802 percpu_counter_inc(&tcp_sockets_allocated); 1803 local_bh_enable(); 1804 1805 return 0; 1806 } 1807 1808 void tcp_v4_destroy_sock(struct sock *sk) 1809 { 1810 struct tcp_sock *tp = tcp_sk(sk); 1811 1812 tcp_clear_xmit_timers(sk); 1813 1814 tcp_cleanup_congestion_control(sk); 1815 1816 /* Cleanup up the write buffer. */ 1817 tcp_write_queue_purge(sk); 1818 1819 /* Cleans up our, hopefully empty, out_of_order_queue. */ 1820 __skb_queue_purge(&tp->out_of_order_queue); 1821 1822 #ifdef CONFIG_TCP_MD5SIG 1823 /* Clean up the MD5 key list, if any */ 1824 if (tp->md5sig_info) { 1825 tcp_v4_clear_md5_list(sk); 1826 kfree(tp->md5sig_info); 1827 tp->md5sig_info = NULL; 1828 } 1829 #endif 1830 1831 #ifdef CONFIG_NET_DMA 1832 /* Cleans up our sk_async_wait_queue */ 1833 __skb_queue_purge(&sk->sk_async_wait_queue); 1834 #endif 1835 1836 /* Clean prequeue, it must be empty really */ 1837 __skb_queue_purge(&tp->ucopy.prequeue); 1838 1839 /* Clean up a referenced TCP bind bucket. */ 1840 if (inet_csk(sk)->icsk_bind_hash) 1841 inet_put_port(sk); 1842 1843 /* 1844 * If sendmsg cached page exists, toss it. 1845 */ 1846 if (sk->sk_sndmsg_page) { 1847 __free_page(sk->sk_sndmsg_page); 1848 sk->sk_sndmsg_page = NULL; 1849 } 1850 1851 percpu_counter_dec(&tcp_sockets_allocated); 1852 } 1853 1854 EXPORT_SYMBOL(tcp_v4_destroy_sock); 1855 1856 #ifdef CONFIG_PROC_FS 1857 /* Proc filesystem TCP sock list dumping. */ 1858 1859 static inline struct inet_timewait_sock *tw_head(struct hlist_nulls_head *head) 1860 { 1861 return hlist_nulls_empty(head) ? NULL : 1862 list_entry(head->first, struct inet_timewait_sock, tw_node); 1863 } 1864 1865 static inline struct inet_timewait_sock *tw_next(struct inet_timewait_sock *tw) 1866 { 1867 return !is_a_nulls(tw->tw_node.next) ? 1868 hlist_nulls_entry(tw->tw_node.next, typeof(*tw), tw_node) : NULL; 1869 } 1870 1871 static void *listening_get_next(struct seq_file *seq, void *cur) 1872 { 1873 struct inet_connection_sock *icsk; 1874 struct hlist_nulls_node *node; 1875 struct sock *sk = cur; 1876 struct inet_listen_hashbucket *ilb; 1877 struct tcp_iter_state *st = seq->private; 1878 struct net *net = seq_file_net(seq); 1879 1880 if (!sk) { 1881 st->bucket = 0; 1882 ilb = &tcp_hashinfo.listening_hash[0]; 1883 spin_lock_bh(&ilb->lock); 1884 sk = sk_nulls_head(&ilb->head); 1885 goto get_sk; 1886 } 1887 ilb = &tcp_hashinfo.listening_hash[st->bucket]; 1888 ++st->num; 1889 1890 if (st->state == TCP_SEQ_STATE_OPENREQ) { 1891 struct request_sock *req = cur; 1892 1893 icsk = inet_csk(st->syn_wait_sk); 1894 req = req->dl_next; 1895 while (1) { 1896 while (req) { 1897 if (req->rsk_ops->family == st->family) { 1898 cur = req; 1899 goto out; 1900 } 1901 req = req->dl_next; 1902 } 1903 if (++st->sbucket >= icsk->icsk_accept_queue.listen_opt->nr_table_entries) 1904 break; 1905 get_req: 1906 req = icsk->icsk_accept_queue.listen_opt->syn_table[st->sbucket]; 1907 } 1908 sk = sk_next(st->syn_wait_sk); 1909 st->state = TCP_SEQ_STATE_LISTENING; 1910 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock); 1911 } else { 1912 icsk = inet_csk(sk); 1913 read_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock); 1914 if (reqsk_queue_len(&icsk->icsk_accept_queue)) 1915 goto start_req; 1916 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock); 1917 sk = sk_next(sk); 1918 } 1919 get_sk: 1920 sk_nulls_for_each_from(sk, node) { 1921 if (sk->sk_family == st->family && net_eq(sock_net(sk), net)) { 1922 cur = sk; 1923 goto out; 1924 } 1925 icsk = inet_csk(sk); 1926 read_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock); 1927 if (reqsk_queue_len(&icsk->icsk_accept_queue)) { 1928 start_req: 1929 st->uid = sock_i_uid(sk); 1930 st->syn_wait_sk = sk; 1931 st->state = TCP_SEQ_STATE_OPENREQ; 1932 st->sbucket = 0; 1933 goto get_req; 1934 } 1935 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock); 1936 } 1937 spin_unlock_bh(&ilb->lock); 1938 if (++st->bucket < INET_LHTABLE_SIZE) { 1939 ilb = &tcp_hashinfo.listening_hash[st->bucket]; 1940 spin_lock_bh(&ilb->lock); 1941 sk = sk_nulls_head(&ilb->head); 1942 goto get_sk; 1943 } 1944 cur = NULL; 1945 out: 1946 return cur; 1947 } 1948 1949 static void *listening_get_idx(struct seq_file *seq, loff_t *pos) 1950 { 1951 void *rc = listening_get_next(seq, NULL); 1952 1953 while (rc && *pos) { 1954 rc = listening_get_next(seq, rc); 1955 --*pos; 1956 } 1957 return rc; 1958 } 1959 1960 static inline int empty_bucket(struct tcp_iter_state *st) 1961 { 1962 return hlist_nulls_empty(&tcp_hashinfo.ehash[st->bucket].chain) && 1963 hlist_nulls_empty(&tcp_hashinfo.ehash[st->bucket].twchain); 1964 } 1965 1966 static void *established_get_first(struct seq_file *seq) 1967 { 1968 struct tcp_iter_state *st = seq->private; 1969 struct net *net = seq_file_net(seq); 1970 void *rc = NULL; 1971 1972 for (st->bucket = 0; st->bucket < tcp_hashinfo.ehash_size; ++st->bucket) { 1973 struct sock *sk; 1974 struct hlist_nulls_node *node; 1975 struct inet_timewait_sock *tw; 1976 spinlock_t *lock = inet_ehash_lockp(&tcp_hashinfo, st->bucket); 1977 1978 /* Lockless fast path for the common case of empty buckets */ 1979 if (empty_bucket(st)) 1980 continue; 1981 1982 spin_lock_bh(lock); 1983 sk_nulls_for_each(sk, node, &tcp_hashinfo.ehash[st->bucket].chain) { 1984 if (sk->sk_family != st->family || 1985 !net_eq(sock_net(sk), net)) { 1986 continue; 1987 } 1988 rc = sk; 1989 goto out; 1990 } 1991 st->state = TCP_SEQ_STATE_TIME_WAIT; 1992 inet_twsk_for_each(tw, node, 1993 &tcp_hashinfo.ehash[st->bucket].twchain) { 1994 if (tw->tw_family != st->family || 1995 !net_eq(twsk_net(tw), net)) { 1996 continue; 1997 } 1998 rc = tw; 1999 goto out; 2000 } 2001 spin_unlock_bh(lock); 2002 st->state = TCP_SEQ_STATE_ESTABLISHED; 2003 } 2004 out: 2005 return rc; 2006 } 2007 2008 static void *established_get_next(struct seq_file *seq, void *cur) 2009 { 2010 struct sock *sk = cur; 2011 struct inet_timewait_sock *tw; 2012 struct hlist_nulls_node *node; 2013 struct tcp_iter_state *st = seq->private; 2014 struct net *net = seq_file_net(seq); 2015 2016 ++st->num; 2017 2018 if (st->state == TCP_SEQ_STATE_TIME_WAIT) { 2019 tw = cur; 2020 tw = tw_next(tw); 2021 get_tw: 2022 while (tw && (tw->tw_family != st->family || !net_eq(twsk_net(tw), net))) { 2023 tw = tw_next(tw); 2024 } 2025 if (tw) { 2026 cur = tw; 2027 goto out; 2028 } 2029 spin_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket)); 2030 st->state = TCP_SEQ_STATE_ESTABLISHED; 2031 2032 /* Look for next non empty bucket */ 2033 while (++st->bucket < tcp_hashinfo.ehash_size && 2034 empty_bucket(st)) 2035 ; 2036 if (st->bucket >= tcp_hashinfo.ehash_size) 2037 return NULL; 2038 2039 spin_lock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket)); 2040 sk = sk_nulls_head(&tcp_hashinfo.ehash[st->bucket].chain); 2041 } else 2042 sk = sk_nulls_next(sk); 2043 2044 sk_nulls_for_each_from(sk, node) { 2045 if (sk->sk_family == st->family && net_eq(sock_net(sk), net)) 2046 goto found; 2047 } 2048 2049 st->state = TCP_SEQ_STATE_TIME_WAIT; 2050 tw = tw_head(&tcp_hashinfo.ehash[st->bucket].twchain); 2051 goto get_tw; 2052 found: 2053 cur = sk; 2054 out: 2055 return cur; 2056 } 2057 2058 static void *established_get_idx(struct seq_file *seq, loff_t pos) 2059 { 2060 void *rc = established_get_first(seq); 2061 2062 while (rc && pos) { 2063 rc = established_get_next(seq, rc); 2064 --pos; 2065 } 2066 return rc; 2067 } 2068 2069 static void *tcp_get_idx(struct seq_file *seq, loff_t pos) 2070 { 2071 void *rc; 2072 struct tcp_iter_state *st = seq->private; 2073 2074 st->state = TCP_SEQ_STATE_LISTENING; 2075 rc = listening_get_idx(seq, &pos); 2076 2077 if (!rc) { 2078 st->state = TCP_SEQ_STATE_ESTABLISHED; 2079 rc = established_get_idx(seq, pos); 2080 } 2081 2082 return rc; 2083 } 2084 2085 static void *tcp_seq_start(struct seq_file *seq, loff_t *pos) 2086 { 2087 struct tcp_iter_state *st = seq->private; 2088 st->state = TCP_SEQ_STATE_LISTENING; 2089 st->num = 0; 2090 return *pos ? tcp_get_idx(seq, *pos - 1) : SEQ_START_TOKEN; 2091 } 2092 2093 static void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos) 2094 { 2095 void *rc = NULL; 2096 struct tcp_iter_state *st; 2097 2098 if (v == SEQ_START_TOKEN) { 2099 rc = tcp_get_idx(seq, 0); 2100 goto out; 2101 } 2102 st = seq->private; 2103 2104 switch (st->state) { 2105 case TCP_SEQ_STATE_OPENREQ: 2106 case TCP_SEQ_STATE_LISTENING: 2107 rc = listening_get_next(seq, v); 2108 if (!rc) { 2109 st->state = TCP_SEQ_STATE_ESTABLISHED; 2110 rc = established_get_first(seq); 2111 } 2112 break; 2113 case TCP_SEQ_STATE_ESTABLISHED: 2114 case TCP_SEQ_STATE_TIME_WAIT: 2115 rc = established_get_next(seq, v); 2116 break; 2117 } 2118 out: 2119 ++*pos; 2120 return rc; 2121 } 2122 2123 static void tcp_seq_stop(struct seq_file *seq, void *v) 2124 { 2125 struct tcp_iter_state *st = seq->private; 2126 2127 switch (st->state) { 2128 case TCP_SEQ_STATE_OPENREQ: 2129 if (v) { 2130 struct inet_connection_sock *icsk = inet_csk(st->syn_wait_sk); 2131 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock); 2132 } 2133 case TCP_SEQ_STATE_LISTENING: 2134 if (v != SEQ_START_TOKEN) 2135 spin_unlock_bh(&tcp_hashinfo.listening_hash[st->bucket].lock); 2136 break; 2137 case TCP_SEQ_STATE_TIME_WAIT: 2138 case TCP_SEQ_STATE_ESTABLISHED: 2139 if (v) 2140 spin_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket)); 2141 break; 2142 } 2143 } 2144 2145 static int tcp_seq_open(struct inode *inode, struct file *file) 2146 { 2147 struct tcp_seq_afinfo *afinfo = PDE(inode)->data; 2148 struct tcp_iter_state *s; 2149 int err; 2150 2151 err = seq_open_net(inode, file, &afinfo->seq_ops, 2152 sizeof(struct tcp_iter_state)); 2153 if (err < 0) 2154 return err; 2155 2156 s = ((struct seq_file *)file->private_data)->private; 2157 s->family = afinfo->family; 2158 return 0; 2159 } 2160 2161 int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo) 2162 { 2163 int rc = 0; 2164 struct proc_dir_entry *p; 2165 2166 afinfo->seq_fops.open = tcp_seq_open; 2167 afinfo->seq_fops.read = seq_read; 2168 afinfo->seq_fops.llseek = seq_lseek; 2169 afinfo->seq_fops.release = seq_release_net; 2170 2171 afinfo->seq_ops.start = tcp_seq_start; 2172 afinfo->seq_ops.next = tcp_seq_next; 2173 afinfo->seq_ops.stop = tcp_seq_stop; 2174 2175 p = proc_create_data(afinfo->name, S_IRUGO, net->proc_net, 2176 &afinfo->seq_fops, afinfo); 2177 if (!p) 2178 rc = -ENOMEM; 2179 return rc; 2180 } 2181 2182 void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo) 2183 { 2184 proc_net_remove(net, afinfo->name); 2185 } 2186 2187 static void get_openreq4(struct sock *sk, struct request_sock *req, 2188 struct seq_file *f, int i, int uid, int *len) 2189 { 2190 const struct inet_request_sock *ireq = inet_rsk(req); 2191 int ttd = req->expires - jiffies; 2192 2193 seq_printf(f, "%4d: %08X:%04X %08X:%04X" 2194 " %02X %08X:%08X %02X:%08lX %08X %5d %8d %u %d %p%n", 2195 i, 2196 ireq->loc_addr, 2197 ntohs(inet_sk(sk)->sport), 2198 ireq->rmt_addr, 2199 ntohs(ireq->rmt_port), 2200 TCP_SYN_RECV, 2201 0, 0, /* could print option size, but that is af dependent. */ 2202 1, /* timers active (only the expire timer) */ 2203 jiffies_to_clock_t(ttd), 2204 req->retrans, 2205 uid, 2206 0, /* non standard timer */ 2207 0, /* open_requests have no inode */ 2208 atomic_read(&sk->sk_refcnt), 2209 req, 2210 len); 2211 } 2212 2213 static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i, int *len) 2214 { 2215 int timer_active; 2216 unsigned long timer_expires; 2217 struct tcp_sock *tp = tcp_sk(sk); 2218 const struct inet_connection_sock *icsk = inet_csk(sk); 2219 struct inet_sock *inet = inet_sk(sk); 2220 __be32 dest = inet->daddr; 2221 __be32 src = inet->rcv_saddr; 2222 __u16 destp = ntohs(inet->dport); 2223 __u16 srcp = ntohs(inet->sport); 2224 2225 if (icsk->icsk_pending == ICSK_TIME_RETRANS) { 2226 timer_active = 1; 2227 timer_expires = icsk->icsk_timeout; 2228 } else if (icsk->icsk_pending == ICSK_TIME_PROBE0) { 2229 timer_active = 4; 2230 timer_expires = icsk->icsk_timeout; 2231 } else if (timer_pending(&sk->sk_timer)) { 2232 timer_active = 2; 2233 timer_expires = sk->sk_timer.expires; 2234 } else { 2235 timer_active = 0; 2236 timer_expires = jiffies; 2237 } 2238 2239 seq_printf(f, "%4d: %08X:%04X %08X:%04X %02X %08X:%08X %02X:%08lX " 2240 "%08X %5d %8d %lu %d %p %lu %lu %u %u %d%n", 2241 i, src, srcp, dest, destp, sk->sk_state, 2242 tp->write_seq - tp->snd_una, 2243 sk->sk_state == TCP_LISTEN ? sk->sk_ack_backlog : 2244 (tp->rcv_nxt - tp->copied_seq), 2245 timer_active, 2246 jiffies_to_clock_t(timer_expires - jiffies), 2247 icsk->icsk_retransmits, 2248 sock_i_uid(sk), 2249 icsk->icsk_probes_out, 2250 sock_i_ino(sk), 2251 atomic_read(&sk->sk_refcnt), sk, 2252 jiffies_to_clock_t(icsk->icsk_rto), 2253 jiffies_to_clock_t(icsk->icsk_ack.ato), 2254 (icsk->icsk_ack.quick << 1) | icsk->icsk_ack.pingpong, 2255 tp->snd_cwnd, 2256 tp->snd_ssthresh >= 0xFFFF ? -1 : tp->snd_ssthresh, 2257 len); 2258 } 2259 2260 static void get_timewait4_sock(struct inet_timewait_sock *tw, 2261 struct seq_file *f, int i, int *len) 2262 { 2263 __be32 dest, src; 2264 __u16 destp, srcp; 2265 int ttd = tw->tw_ttd - jiffies; 2266 2267 if (ttd < 0) 2268 ttd = 0; 2269 2270 dest = tw->tw_daddr; 2271 src = tw->tw_rcv_saddr; 2272 destp = ntohs(tw->tw_dport); 2273 srcp = ntohs(tw->tw_sport); 2274 2275 seq_printf(f, "%4d: %08X:%04X %08X:%04X" 2276 " %02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %p%n", 2277 i, src, srcp, dest, destp, tw->tw_substate, 0, 0, 2278 3, jiffies_to_clock_t(ttd), 0, 0, 0, 0, 2279 atomic_read(&tw->tw_refcnt), tw, len); 2280 } 2281 2282 #define TMPSZ 150 2283 2284 static int tcp4_seq_show(struct seq_file *seq, void *v) 2285 { 2286 struct tcp_iter_state *st; 2287 int len; 2288 2289 if (v == SEQ_START_TOKEN) { 2290 seq_printf(seq, "%-*s\n", TMPSZ - 1, 2291 " sl local_address rem_address st tx_queue " 2292 "rx_queue tr tm->when retrnsmt uid timeout " 2293 "inode"); 2294 goto out; 2295 } 2296 st = seq->private; 2297 2298 switch (st->state) { 2299 case TCP_SEQ_STATE_LISTENING: 2300 case TCP_SEQ_STATE_ESTABLISHED: 2301 get_tcp4_sock(v, seq, st->num, &len); 2302 break; 2303 case TCP_SEQ_STATE_OPENREQ: 2304 get_openreq4(st->syn_wait_sk, v, seq, st->num, st->uid, &len); 2305 break; 2306 case TCP_SEQ_STATE_TIME_WAIT: 2307 get_timewait4_sock(v, seq, st->num, &len); 2308 break; 2309 } 2310 seq_printf(seq, "%*s\n", TMPSZ - 1 - len, ""); 2311 out: 2312 return 0; 2313 } 2314 2315 static struct tcp_seq_afinfo tcp4_seq_afinfo = { 2316 .name = "tcp", 2317 .family = AF_INET, 2318 .seq_fops = { 2319 .owner = THIS_MODULE, 2320 }, 2321 .seq_ops = { 2322 .show = tcp4_seq_show, 2323 }, 2324 }; 2325 2326 static int tcp4_proc_init_net(struct net *net) 2327 { 2328 return tcp_proc_register(net, &tcp4_seq_afinfo); 2329 } 2330 2331 static void tcp4_proc_exit_net(struct net *net) 2332 { 2333 tcp_proc_unregister(net, &tcp4_seq_afinfo); 2334 } 2335 2336 static struct pernet_operations tcp4_net_ops = { 2337 .init = tcp4_proc_init_net, 2338 .exit = tcp4_proc_exit_net, 2339 }; 2340 2341 int __init tcp4_proc_init(void) 2342 { 2343 return register_pernet_subsys(&tcp4_net_ops); 2344 } 2345 2346 void tcp4_proc_exit(void) 2347 { 2348 unregister_pernet_subsys(&tcp4_net_ops); 2349 } 2350 #endif /* CONFIG_PROC_FS */ 2351 2352 struct sk_buff **tcp4_gro_receive(struct sk_buff **head, struct sk_buff *skb) 2353 { 2354 struct iphdr *iph = ip_hdr(skb); 2355 2356 switch (skb->ip_summed) { 2357 case CHECKSUM_COMPLETE: 2358 if (!tcp_v4_check(skb->len, iph->saddr, iph->daddr, 2359 skb->csum)) { 2360 skb->ip_summed = CHECKSUM_UNNECESSARY; 2361 break; 2362 } 2363 2364 /* fall through */ 2365 case CHECKSUM_NONE: 2366 NAPI_GRO_CB(skb)->flush = 1; 2367 return NULL; 2368 } 2369 2370 return tcp_gro_receive(head, skb); 2371 } 2372 EXPORT_SYMBOL(tcp4_gro_receive); 2373 2374 int tcp4_gro_complete(struct sk_buff *skb) 2375 { 2376 struct iphdr *iph = ip_hdr(skb); 2377 struct tcphdr *th = tcp_hdr(skb); 2378 2379 th->check = ~tcp_v4_check(skb->len - skb_transport_offset(skb), 2380 iph->saddr, iph->daddr, 0); 2381 skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4; 2382 2383 return tcp_gro_complete(skb); 2384 } 2385 EXPORT_SYMBOL(tcp4_gro_complete); 2386 2387 struct proto tcp_prot = { 2388 .name = "TCP", 2389 .owner = THIS_MODULE, 2390 .close = tcp_close, 2391 .connect = tcp_v4_connect, 2392 .disconnect = tcp_disconnect, 2393 .accept = inet_csk_accept, 2394 .ioctl = tcp_ioctl, 2395 .init = tcp_v4_init_sock, 2396 .destroy = tcp_v4_destroy_sock, 2397 .shutdown = tcp_shutdown, 2398 .setsockopt = tcp_setsockopt, 2399 .getsockopt = tcp_getsockopt, 2400 .recvmsg = tcp_recvmsg, 2401 .backlog_rcv = tcp_v4_do_rcv, 2402 .hash = inet_hash, 2403 .unhash = inet_unhash, 2404 .get_port = inet_csk_get_port, 2405 .enter_memory_pressure = tcp_enter_memory_pressure, 2406 .sockets_allocated = &tcp_sockets_allocated, 2407 .orphan_count = &tcp_orphan_count, 2408 .memory_allocated = &tcp_memory_allocated, 2409 .memory_pressure = &tcp_memory_pressure, 2410 .sysctl_mem = sysctl_tcp_mem, 2411 .sysctl_wmem = sysctl_tcp_wmem, 2412 .sysctl_rmem = sysctl_tcp_rmem, 2413 .max_header = MAX_TCP_HEADER, 2414 .obj_size = sizeof(struct tcp_sock), 2415 .slab_flags = SLAB_DESTROY_BY_RCU, 2416 .twsk_prot = &tcp_timewait_sock_ops, 2417 .rsk_prot = &tcp_request_sock_ops, 2418 .h.hashinfo = &tcp_hashinfo, 2419 #ifdef CONFIG_COMPAT 2420 .compat_setsockopt = compat_tcp_setsockopt, 2421 .compat_getsockopt = compat_tcp_getsockopt, 2422 #endif 2423 }; 2424 2425 2426 static int __net_init tcp_sk_init(struct net *net) 2427 { 2428 return inet_ctl_sock_create(&net->ipv4.tcp_sock, 2429 PF_INET, SOCK_RAW, IPPROTO_TCP, net); 2430 } 2431 2432 static void __net_exit tcp_sk_exit(struct net *net) 2433 { 2434 inet_ctl_sock_destroy(net->ipv4.tcp_sock); 2435 inet_twsk_purge(net, &tcp_hashinfo, &tcp_death_row, AF_INET); 2436 } 2437 2438 static struct pernet_operations __net_initdata tcp_sk_ops = { 2439 .init = tcp_sk_init, 2440 .exit = tcp_sk_exit, 2441 }; 2442 2443 void __init tcp_v4_init(void) 2444 { 2445 inet_hashinfo_init(&tcp_hashinfo); 2446 if (register_pernet_subsys(&tcp_sk_ops)) 2447 panic("Failed to create the TCP control socket.\n"); 2448 } 2449 2450 EXPORT_SYMBOL(ipv4_specific); 2451 EXPORT_SYMBOL(tcp_hashinfo); 2452 EXPORT_SYMBOL(tcp_prot); 2453 EXPORT_SYMBOL(tcp_v4_conn_request); 2454 EXPORT_SYMBOL(tcp_v4_connect); 2455 EXPORT_SYMBOL(tcp_v4_do_rcv); 2456 EXPORT_SYMBOL(tcp_v4_remember_stamp); 2457 EXPORT_SYMBOL(tcp_v4_send_check); 2458 EXPORT_SYMBOL(tcp_v4_syn_recv_sock); 2459 2460 #ifdef CONFIG_PROC_FS 2461 EXPORT_SYMBOL(tcp_proc_register); 2462 EXPORT_SYMBOL(tcp_proc_unregister); 2463 #endif 2464 EXPORT_SYMBOL(sysctl_tcp_low_latency); 2465 2466