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 * Version: $Id: tcp.c,v 1.216 2002/02/01 22:01:04 davem Exp $ 9 * 10 * Authors: Ross Biro 11 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> 12 * Mark Evans, <evansmp@uhura.aston.ac.uk> 13 * Corey Minyard <wf-rch!minyard@relay.EU.net> 14 * Florian La Roche, <flla@stud.uni-sb.de> 15 * Charles Hedrick, <hedrick@klinzhai.rutgers.edu> 16 * Linus Torvalds, <torvalds@cs.helsinki.fi> 17 * Alan Cox, <gw4pts@gw4pts.ampr.org> 18 * Matthew Dillon, <dillon@apollo.west.oic.com> 19 * Arnt Gulbrandsen, <agulbra@nvg.unit.no> 20 * Jorge Cwik, <jorge@laser.satlink.net> 21 * 22 * Fixes: 23 * Alan Cox : Numerous verify_area() calls 24 * Alan Cox : Set the ACK bit on a reset 25 * Alan Cox : Stopped it crashing if it closed while 26 * sk->inuse=1 and was trying to connect 27 * (tcp_err()). 28 * Alan Cox : All icmp error handling was broken 29 * pointers passed where wrong and the 30 * socket was looked up backwards. Nobody 31 * tested any icmp error code obviously. 32 * Alan Cox : tcp_err() now handled properly. It 33 * wakes people on errors. poll 34 * behaves and the icmp error race 35 * has gone by moving it into sock.c 36 * Alan Cox : tcp_send_reset() fixed to work for 37 * everything not just packets for 38 * unknown sockets. 39 * Alan Cox : tcp option processing. 40 * Alan Cox : Reset tweaked (still not 100%) [Had 41 * syn rule wrong] 42 * Herp Rosmanith : More reset fixes 43 * Alan Cox : No longer acks invalid rst frames. 44 * Acking any kind of RST is right out. 45 * Alan Cox : Sets an ignore me flag on an rst 46 * receive otherwise odd bits of prattle 47 * escape still 48 * Alan Cox : Fixed another acking RST frame bug. 49 * Should stop LAN workplace lockups. 50 * Alan Cox : Some tidyups using the new skb list 51 * facilities 52 * Alan Cox : sk->keepopen now seems to work 53 * Alan Cox : Pulls options out correctly on accepts 54 * Alan Cox : Fixed assorted sk->rqueue->next errors 55 * Alan Cox : PSH doesn't end a TCP read. Switched a 56 * bit to skb ops. 57 * Alan Cox : Tidied tcp_data to avoid a potential 58 * nasty. 59 * Alan Cox : Added some better commenting, as the 60 * tcp is hard to follow 61 * Alan Cox : Removed incorrect check for 20 * psh 62 * Michael O'Reilly : ack < copied bug fix. 63 * Johannes Stille : Misc tcp fixes (not all in yet). 64 * Alan Cox : FIN with no memory -> CRASH 65 * Alan Cox : Added socket option proto entries. 66 * Also added awareness of them to accept. 67 * Alan Cox : Added TCP options (SOL_TCP) 68 * Alan Cox : Switched wakeup calls to callbacks, 69 * so the kernel can layer network 70 * sockets. 71 * Alan Cox : Use ip_tos/ip_ttl settings. 72 * Alan Cox : Handle FIN (more) properly (we hope). 73 * Alan Cox : RST frames sent on unsynchronised 74 * state ack error. 75 * Alan Cox : Put in missing check for SYN bit. 76 * Alan Cox : Added tcp_select_window() aka NET2E 77 * window non shrink trick. 78 * Alan Cox : Added a couple of small NET2E timer 79 * fixes 80 * Charles Hedrick : TCP fixes 81 * Toomas Tamm : TCP window fixes 82 * Alan Cox : Small URG fix to rlogin ^C ack fight 83 * Charles Hedrick : Rewrote most of it to actually work 84 * Linus : Rewrote tcp_read() and URG handling 85 * completely 86 * Gerhard Koerting: Fixed some missing timer handling 87 * Matthew Dillon : Reworked TCP machine states as per RFC 88 * Gerhard Koerting: PC/TCP workarounds 89 * Adam Caldwell : Assorted timer/timing errors 90 * Matthew Dillon : Fixed another RST bug 91 * Alan Cox : Move to kernel side addressing changes. 92 * Alan Cox : Beginning work on TCP fastpathing 93 * (not yet usable) 94 * Arnt Gulbrandsen: Turbocharged tcp_check() routine. 95 * Alan Cox : TCP fast path debugging 96 * Alan Cox : Window clamping 97 * Michael Riepe : Bug in tcp_check() 98 * Matt Dillon : More TCP improvements and RST bug fixes 99 * Matt Dillon : Yet more small nasties remove from the 100 * TCP code (Be very nice to this man if 101 * tcp finally works 100%) 8) 102 * Alan Cox : BSD accept semantics. 103 * Alan Cox : Reset on closedown bug. 104 * Peter De Schrijver : ENOTCONN check missing in tcp_sendto(). 105 * Michael Pall : Handle poll() after URG properly in 106 * all cases. 107 * Michael Pall : Undo the last fix in tcp_read_urg() 108 * (multi URG PUSH broke rlogin). 109 * Michael Pall : Fix the multi URG PUSH problem in 110 * tcp_readable(), poll() after URG 111 * works now. 112 * Michael Pall : recv(...,MSG_OOB) never blocks in the 113 * BSD api. 114 * Alan Cox : Changed the semantics of sk->socket to 115 * fix a race and a signal problem with 116 * accept() and async I/O. 117 * Alan Cox : Relaxed the rules on tcp_sendto(). 118 * Yury Shevchuk : Really fixed accept() blocking problem. 119 * Craig I. Hagan : Allow for BSD compatible TIME_WAIT for 120 * clients/servers which listen in on 121 * fixed ports. 122 * Alan Cox : Cleaned the above up and shrank it to 123 * a sensible code size. 124 * Alan Cox : Self connect lockup fix. 125 * Alan Cox : No connect to multicast. 126 * Ross Biro : Close unaccepted children on master 127 * socket close. 128 * Alan Cox : Reset tracing code. 129 * Alan Cox : Spurious resets on shutdown. 130 * Alan Cox : Giant 15 minute/60 second timer error 131 * Alan Cox : Small whoops in polling before an 132 * accept. 133 * Alan Cox : Kept the state trace facility since 134 * it's handy for debugging. 135 * Alan Cox : More reset handler fixes. 136 * Alan Cox : Started rewriting the code based on 137 * the RFC's for other useful protocol 138 * references see: Comer, KA9Q NOS, and 139 * for a reference on the difference 140 * between specifications and how BSD 141 * works see the 4.4lite source. 142 * A.N.Kuznetsov : Don't time wait on completion of tidy 143 * close. 144 * Linus Torvalds : Fin/Shutdown & copied_seq changes. 145 * Linus Torvalds : Fixed BSD port reuse to work first syn 146 * Alan Cox : Reimplemented timers as per the RFC 147 * and using multiple timers for sanity. 148 * Alan Cox : Small bug fixes, and a lot of new 149 * comments. 150 * Alan Cox : Fixed dual reader crash by locking 151 * the buffers (much like datagram.c) 152 * Alan Cox : Fixed stuck sockets in probe. A probe 153 * now gets fed up of retrying without 154 * (even a no space) answer. 155 * Alan Cox : Extracted closing code better 156 * Alan Cox : Fixed the closing state machine to 157 * resemble the RFC. 158 * Alan Cox : More 'per spec' fixes. 159 * Jorge Cwik : Even faster checksumming. 160 * Alan Cox : tcp_data() doesn't ack illegal PSH 161 * only frames. At least one pc tcp stack 162 * generates them. 163 * Alan Cox : Cache last socket. 164 * Alan Cox : Per route irtt. 165 * Matt Day : poll()->select() match BSD precisely on error 166 * Alan Cox : New buffers 167 * Marc Tamsky : Various sk->prot->retransmits and 168 * sk->retransmits misupdating fixed. 169 * Fixed tcp_write_timeout: stuck close, 170 * and TCP syn retries gets used now. 171 * Mark Yarvis : In tcp_read_wakeup(), don't send an 172 * ack if state is TCP_CLOSED. 173 * Alan Cox : Look up device on a retransmit - routes may 174 * change. Doesn't yet cope with MSS shrink right 175 * but it's a start! 176 * Marc Tamsky : Closing in closing fixes. 177 * Mike Shaver : RFC1122 verifications. 178 * Alan Cox : rcv_saddr errors. 179 * Alan Cox : Block double connect(). 180 * Alan Cox : Small hooks for enSKIP. 181 * Alexey Kuznetsov: Path MTU discovery. 182 * Alan Cox : Support soft errors. 183 * Alan Cox : Fix MTU discovery pathological case 184 * when the remote claims no mtu! 185 * Marc Tamsky : TCP_CLOSE fix. 186 * Colin (G3TNE) : Send a reset on syn ack replies in 187 * window but wrong (fixes NT lpd problems) 188 * Pedro Roque : Better TCP window handling, delayed ack. 189 * Joerg Reuter : No modification of locked buffers in 190 * tcp_do_retransmit() 191 * Eric Schenk : Changed receiver side silly window 192 * avoidance algorithm to BSD style 193 * algorithm. This doubles throughput 194 * against machines running Solaris, 195 * and seems to result in general 196 * improvement. 197 * Stefan Magdalinski : adjusted tcp_readable() to fix FIONREAD 198 * Willy Konynenberg : Transparent proxying support. 199 * Mike McLagan : Routing by source 200 * Keith Owens : Do proper merging with partial SKB's in 201 * tcp_do_sendmsg to avoid burstiness. 202 * Eric Schenk : Fix fast close down bug with 203 * shutdown() followed by close(). 204 * Andi Kleen : Make poll agree with SIGIO 205 * Salvatore Sanfilippo : Support SO_LINGER with linger == 1 and 206 * lingertime == 0 (RFC 793 ABORT Call) 207 * Hirokazu Takahashi : Use copy_from_user() instead of 208 * csum_and_copy_from_user() if possible. 209 * 210 * This program is free software; you can redistribute it and/or 211 * modify it under the terms of the GNU General Public License 212 * as published by the Free Software Foundation; either version 213 * 2 of the License, or(at your option) any later version. 214 * 215 * Description of States: 216 * 217 * TCP_SYN_SENT sent a connection request, waiting for ack 218 * 219 * TCP_SYN_RECV received a connection request, sent ack, 220 * waiting for final ack in three-way handshake. 221 * 222 * TCP_ESTABLISHED connection established 223 * 224 * TCP_FIN_WAIT1 our side has shutdown, waiting to complete 225 * transmission of remaining buffered data 226 * 227 * TCP_FIN_WAIT2 all buffered data sent, waiting for remote 228 * to shutdown 229 * 230 * TCP_CLOSING both sides have shutdown but we still have 231 * data we have to finish sending 232 * 233 * TCP_TIME_WAIT timeout to catch resent junk before entering 234 * closed, can only be entered from FIN_WAIT2 235 * or CLOSING. Required because the other end 236 * may not have gotten our last ACK causing it 237 * to retransmit the data packet (which we ignore) 238 * 239 * TCP_CLOSE_WAIT remote side has shutdown and is waiting for 240 * us to finish writing our data and to shutdown 241 * (we have to close() to move on to LAST_ACK) 242 * 243 * TCP_LAST_ACK out side has shutdown after remote has 244 * shutdown. There may still be data in our 245 * buffer that we have to finish sending 246 * 247 * TCP_CLOSE socket is finished 248 */ 249 250 #include <linux/module.h> 251 #include <linux/types.h> 252 #include <linux/fcntl.h> 253 #include <linux/poll.h> 254 #include <linux/init.h> 255 #include <linux/smp_lock.h> 256 #include <linux/fs.h> 257 #include <linux/random.h> 258 #include <linux/bootmem.h> 259 #include <linux/cache.h> 260 #include <linux/err.h> 261 #include <linux/crypto.h> 262 263 #include <net/icmp.h> 264 #include <net/tcp.h> 265 #include <net/xfrm.h> 266 #include <net/ip.h> 267 #include <net/netdma.h> 268 269 #include <asm/uaccess.h> 270 #include <asm/ioctls.h> 271 272 int sysctl_tcp_fin_timeout __read_mostly = TCP_FIN_TIMEOUT; 273 274 DEFINE_SNMP_STAT(struct tcp_mib, tcp_statistics) __read_mostly; 275 276 atomic_t tcp_orphan_count = ATOMIC_INIT(0); 277 278 EXPORT_SYMBOL_GPL(tcp_orphan_count); 279 280 int sysctl_tcp_mem[3] __read_mostly; 281 int sysctl_tcp_wmem[3] __read_mostly; 282 int sysctl_tcp_rmem[3] __read_mostly; 283 284 EXPORT_SYMBOL(sysctl_tcp_mem); 285 EXPORT_SYMBOL(sysctl_tcp_rmem); 286 EXPORT_SYMBOL(sysctl_tcp_wmem); 287 288 atomic_t tcp_memory_allocated; /* Current allocated memory. */ 289 atomic_t tcp_sockets_allocated; /* Current number of TCP sockets. */ 290 291 EXPORT_SYMBOL(tcp_memory_allocated); 292 EXPORT_SYMBOL(tcp_sockets_allocated); 293 294 /* 295 * Pressure flag: try to collapse. 296 * Technical note: it is used by multiple contexts non atomically. 297 * All the sk_stream_mem_schedule() is of this nature: accounting 298 * is strict, actions are advisory and have some latency. 299 */ 300 int tcp_memory_pressure __read_mostly; 301 302 EXPORT_SYMBOL(tcp_memory_pressure); 303 304 void tcp_enter_memory_pressure(void) 305 { 306 if (!tcp_memory_pressure) { 307 NET_INC_STATS(LINUX_MIB_TCPMEMORYPRESSURES); 308 tcp_memory_pressure = 1; 309 } 310 } 311 312 EXPORT_SYMBOL(tcp_enter_memory_pressure); 313 314 /* 315 * Wait for a TCP event. 316 * 317 * Note that we don't need to lock the socket, as the upper poll layers 318 * take care of normal races (between the test and the event) and we don't 319 * go look at any of the socket buffers directly. 320 */ 321 unsigned int tcp_poll(struct file *file, struct socket *sock, poll_table *wait) 322 { 323 unsigned int mask; 324 struct sock *sk = sock->sk; 325 struct tcp_sock *tp = tcp_sk(sk); 326 327 poll_wait(file, sk->sk_sleep, wait); 328 if (sk->sk_state == TCP_LISTEN) 329 return inet_csk_listen_poll(sk); 330 331 /* Socket is not locked. We are protected from async events 332 by poll logic and correct handling of state changes 333 made by another threads is impossible in any case. 334 */ 335 336 mask = 0; 337 if (sk->sk_err) 338 mask = POLLERR; 339 340 /* 341 * POLLHUP is certainly not done right. But poll() doesn't 342 * have a notion of HUP in just one direction, and for a 343 * socket the read side is more interesting. 344 * 345 * Some poll() documentation says that POLLHUP is incompatible 346 * with the POLLOUT/POLLWR flags, so somebody should check this 347 * all. But careful, it tends to be safer to return too many 348 * bits than too few, and you can easily break real applications 349 * if you don't tell them that something has hung up! 350 * 351 * Check-me. 352 * 353 * Check number 1. POLLHUP is _UNMASKABLE_ event (see UNIX98 and 354 * our fs/select.c). It means that after we received EOF, 355 * poll always returns immediately, making impossible poll() on write() 356 * in state CLOSE_WAIT. One solution is evident --- to set POLLHUP 357 * if and only if shutdown has been made in both directions. 358 * Actually, it is interesting to look how Solaris and DUX 359 * solve this dilemma. I would prefer, if PULLHUP were maskable, 360 * then we could set it on SND_SHUTDOWN. BTW examples given 361 * in Stevens' books assume exactly this behaviour, it explains 362 * why PULLHUP is incompatible with POLLOUT. --ANK 363 * 364 * NOTE. Check for TCP_CLOSE is added. The goal is to prevent 365 * blocking on fresh not-connected or disconnected socket. --ANK 366 */ 367 if (sk->sk_shutdown == SHUTDOWN_MASK || sk->sk_state == TCP_CLOSE) 368 mask |= POLLHUP; 369 if (sk->sk_shutdown & RCV_SHUTDOWN) 370 mask |= POLLIN | POLLRDNORM | POLLRDHUP; 371 372 /* Connected? */ 373 if ((1 << sk->sk_state) & ~(TCPF_SYN_SENT | TCPF_SYN_RECV)) { 374 /* Potential race condition. If read of tp below will 375 * escape above sk->sk_state, we can be illegally awaken 376 * in SYN_* states. */ 377 if ((tp->rcv_nxt != tp->copied_seq) && 378 (tp->urg_seq != tp->copied_seq || 379 tp->rcv_nxt != tp->copied_seq + 1 || 380 sock_flag(sk, SOCK_URGINLINE) || !tp->urg_data)) 381 mask |= POLLIN | POLLRDNORM; 382 383 if (!(sk->sk_shutdown & SEND_SHUTDOWN)) { 384 if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk)) { 385 mask |= POLLOUT | POLLWRNORM; 386 } else { /* send SIGIO later */ 387 set_bit(SOCK_ASYNC_NOSPACE, 388 &sk->sk_socket->flags); 389 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags); 390 391 /* Race breaker. If space is freed after 392 * wspace test but before the flags are set, 393 * IO signal will be lost. 394 */ 395 if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk)) 396 mask |= POLLOUT | POLLWRNORM; 397 } 398 } 399 400 if (tp->urg_data & TCP_URG_VALID) 401 mask |= POLLPRI; 402 } 403 return mask; 404 } 405 406 int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg) 407 { 408 struct tcp_sock *tp = tcp_sk(sk); 409 int answ; 410 411 switch (cmd) { 412 case SIOCINQ: 413 if (sk->sk_state == TCP_LISTEN) 414 return -EINVAL; 415 416 lock_sock(sk); 417 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) 418 answ = 0; 419 else if (sock_flag(sk, SOCK_URGINLINE) || 420 !tp->urg_data || 421 before(tp->urg_seq, tp->copied_seq) || 422 !before(tp->urg_seq, tp->rcv_nxt)) { 423 answ = tp->rcv_nxt - tp->copied_seq; 424 425 /* Subtract 1, if FIN is in queue. */ 426 if (answ && !skb_queue_empty(&sk->sk_receive_queue)) 427 answ -= 428 tcp_hdr((struct sk_buff *)sk->sk_receive_queue.prev)->fin; 429 } else 430 answ = tp->urg_seq - tp->copied_seq; 431 release_sock(sk); 432 break; 433 case SIOCATMARK: 434 answ = tp->urg_data && tp->urg_seq == tp->copied_seq; 435 break; 436 case SIOCOUTQ: 437 if (sk->sk_state == TCP_LISTEN) 438 return -EINVAL; 439 440 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) 441 answ = 0; 442 else 443 answ = tp->write_seq - tp->snd_una; 444 break; 445 default: 446 return -ENOIOCTLCMD; 447 } 448 449 return put_user(answ, (int __user *)arg); 450 } 451 452 static inline void tcp_mark_push(struct tcp_sock *tp, struct sk_buff *skb) 453 { 454 TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_PSH; 455 tp->pushed_seq = tp->write_seq; 456 } 457 458 static inline int forced_push(struct tcp_sock *tp) 459 { 460 return after(tp->write_seq, tp->pushed_seq + (tp->max_window >> 1)); 461 } 462 463 static inline void skb_entail(struct sock *sk, struct sk_buff *skb) 464 { 465 struct tcp_sock *tp = tcp_sk(sk); 466 struct tcp_skb_cb *tcb = TCP_SKB_CB(skb); 467 468 skb->csum = 0; 469 tcb->seq = tcb->end_seq = tp->write_seq; 470 tcb->flags = TCPCB_FLAG_ACK; 471 tcb->sacked = 0; 472 skb_header_release(skb); 473 tcp_add_write_queue_tail(sk, skb); 474 sk_charge_skb(sk, skb); 475 if (tp->nonagle & TCP_NAGLE_PUSH) 476 tp->nonagle &= ~TCP_NAGLE_PUSH; 477 } 478 479 static inline void tcp_mark_urg(struct tcp_sock *tp, int flags, 480 struct sk_buff *skb) 481 { 482 if (flags & MSG_OOB) { 483 tp->urg_mode = 1; 484 tp->snd_up = tp->write_seq; 485 TCP_SKB_CB(skb)->sacked |= TCPCB_URG; 486 } 487 } 488 489 static inline void tcp_push(struct sock *sk, int flags, int mss_now, 490 int nonagle) 491 { 492 struct tcp_sock *tp = tcp_sk(sk); 493 494 if (tcp_send_head(sk)) { 495 struct sk_buff *skb = tcp_write_queue_tail(sk); 496 if (!(flags & MSG_MORE) || forced_push(tp)) 497 tcp_mark_push(tp, skb); 498 tcp_mark_urg(tp, flags, skb); 499 __tcp_push_pending_frames(sk, mss_now, 500 (flags & MSG_MORE) ? TCP_NAGLE_CORK : nonagle); 501 } 502 } 503 504 static ssize_t do_tcp_sendpages(struct sock *sk, struct page **pages, int poffset, 505 size_t psize, int flags) 506 { 507 struct tcp_sock *tp = tcp_sk(sk); 508 int mss_now, size_goal; 509 int err; 510 ssize_t copied; 511 long timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT); 512 513 /* Wait for a connection to finish. */ 514 if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) 515 if ((err = sk_stream_wait_connect(sk, &timeo)) != 0) 516 goto out_err; 517 518 clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags); 519 520 mss_now = tcp_current_mss(sk, !(flags&MSG_OOB)); 521 size_goal = tp->xmit_size_goal; 522 copied = 0; 523 524 err = -EPIPE; 525 if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN)) 526 goto do_error; 527 528 while (psize > 0) { 529 struct sk_buff *skb = tcp_write_queue_tail(sk); 530 struct page *page = pages[poffset / PAGE_SIZE]; 531 int copy, i, can_coalesce; 532 int offset = poffset % PAGE_SIZE; 533 int size = min_t(size_t, psize, PAGE_SIZE - offset); 534 535 if (!tcp_send_head(sk) || (copy = size_goal - skb->len) <= 0) { 536 new_segment: 537 if (!sk_stream_memory_free(sk)) 538 goto wait_for_sndbuf; 539 540 skb = sk_stream_alloc_pskb(sk, 0, 0, 541 sk->sk_allocation); 542 if (!skb) 543 goto wait_for_memory; 544 545 skb_entail(sk, skb); 546 copy = size_goal; 547 } 548 549 if (copy > size) 550 copy = size; 551 552 i = skb_shinfo(skb)->nr_frags; 553 can_coalesce = skb_can_coalesce(skb, i, page, offset); 554 if (!can_coalesce && i >= MAX_SKB_FRAGS) { 555 tcp_mark_push(tp, skb); 556 goto new_segment; 557 } 558 if (!sk_stream_wmem_schedule(sk, copy)) 559 goto wait_for_memory; 560 561 if (can_coalesce) { 562 skb_shinfo(skb)->frags[i - 1].size += copy; 563 } else { 564 get_page(page); 565 skb_fill_page_desc(skb, i, page, offset, copy); 566 } 567 568 skb->len += copy; 569 skb->data_len += copy; 570 skb->truesize += copy; 571 sk->sk_wmem_queued += copy; 572 sk->sk_forward_alloc -= copy; 573 skb->ip_summed = CHECKSUM_PARTIAL; 574 tp->write_seq += copy; 575 TCP_SKB_CB(skb)->end_seq += copy; 576 skb_shinfo(skb)->gso_segs = 0; 577 578 if (!copied) 579 TCP_SKB_CB(skb)->flags &= ~TCPCB_FLAG_PSH; 580 581 copied += copy; 582 poffset += copy; 583 if (!(psize -= copy)) 584 goto out; 585 586 if (skb->len < mss_now || (flags & MSG_OOB)) 587 continue; 588 589 if (forced_push(tp)) { 590 tcp_mark_push(tp, skb); 591 __tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_PUSH); 592 } else if (skb == tcp_send_head(sk)) 593 tcp_push_one(sk, mss_now); 594 continue; 595 596 wait_for_sndbuf: 597 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags); 598 wait_for_memory: 599 if (copied) 600 tcp_push(sk, flags & ~MSG_MORE, mss_now, TCP_NAGLE_PUSH); 601 602 if ((err = sk_stream_wait_memory(sk, &timeo)) != 0) 603 goto do_error; 604 605 mss_now = tcp_current_mss(sk, !(flags&MSG_OOB)); 606 size_goal = tp->xmit_size_goal; 607 } 608 609 out: 610 if (copied) 611 tcp_push(sk, flags, mss_now, tp->nonagle); 612 return copied; 613 614 do_error: 615 if (copied) 616 goto out; 617 out_err: 618 return sk_stream_error(sk, flags, err); 619 } 620 621 ssize_t tcp_sendpage(struct socket *sock, struct page *page, int offset, 622 size_t size, int flags) 623 { 624 ssize_t res; 625 struct sock *sk = sock->sk; 626 627 if (!(sk->sk_route_caps & NETIF_F_SG) || 628 !(sk->sk_route_caps & NETIF_F_ALL_CSUM)) 629 return sock_no_sendpage(sock, page, offset, size, flags); 630 631 lock_sock(sk); 632 TCP_CHECK_TIMER(sk); 633 res = do_tcp_sendpages(sk, &page, offset, size, flags); 634 TCP_CHECK_TIMER(sk); 635 release_sock(sk); 636 return res; 637 } 638 639 #define TCP_PAGE(sk) (sk->sk_sndmsg_page) 640 #define TCP_OFF(sk) (sk->sk_sndmsg_off) 641 642 static inline int select_size(struct sock *sk) 643 { 644 struct tcp_sock *tp = tcp_sk(sk); 645 int tmp = tp->mss_cache; 646 647 if (sk->sk_route_caps & NETIF_F_SG) { 648 if (sk_can_gso(sk)) 649 tmp = 0; 650 else { 651 int pgbreak = SKB_MAX_HEAD(MAX_TCP_HEADER); 652 653 if (tmp >= pgbreak && 654 tmp <= pgbreak + (MAX_SKB_FRAGS - 1) * PAGE_SIZE) 655 tmp = pgbreak; 656 } 657 } 658 659 return tmp; 660 } 661 662 int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, 663 size_t size) 664 { 665 struct iovec *iov; 666 struct tcp_sock *tp = tcp_sk(sk); 667 struct sk_buff *skb; 668 int iovlen, flags; 669 int mss_now, size_goal; 670 int err, copied; 671 long timeo; 672 673 lock_sock(sk); 674 TCP_CHECK_TIMER(sk); 675 676 flags = msg->msg_flags; 677 timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT); 678 679 /* Wait for a connection to finish. */ 680 if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) 681 if ((err = sk_stream_wait_connect(sk, &timeo)) != 0) 682 goto out_err; 683 684 /* This should be in poll */ 685 clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags); 686 687 mss_now = tcp_current_mss(sk, !(flags&MSG_OOB)); 688 size_goal = tp->xmit_size_goal; 689 690 /* Ok commence sending. */ 691 iovlen = msg->msg_iovlen; 692 iov = msg->msg_iov; 693 copied = 0; 694 695 err = -EPIPE; 696 if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN)) 697 goto do_error; 698 699 while (--iovlen >= 0) { 700 int seglen = iov->iov_len; 701 unsigned char __user *from = iov->iov_base; 702 703 iov++; 704 705 while (seglen > 0) { 706 int copy; 707 708 skb = tcp_write_queue_tail(sk); 709 710 if (!tcp_send_head(sk) || 711 (copy = size_goal - skb->len) <= 0) { 712 713 new_segment: 714 /* Allocate new segment. If the interface is SG, 715 * allocate skb fitting to single page. 716 */ 717 if (!sk_stream_memory_free(sk)) 718 goto wait_for_sndbuf; 719 720 skb = sk_stream_alloc_pskb(sk, select_size(sk), 721 0, sk->sk_allocation); 722 if (!skb) 723 goto wait_for_memory; 724 725 /* 726 * Check whether we can use HW checksum. 727 */ 728 if (sk->sk_route_caps & NETIF_F_ALL_CSUM) 729 skb->ip_summed = CHECKSUM_PARTIAL; 730 731 skb_entail(sk, skb); 732 copy = size_goal; 733 } 734 735 /* Try to append data to the end of skb. */ 736 if (copy > seglen) 737 copy = seglen; 738 739 /* Where to copy to? */ 740 if (skb_tailroom(skb) > 0) { 741 /* We have some space in skb head. Superb! */ 742 if (copy > skb_tailroom(skb)) 743 copy = skb_tailroom(skb); 744 if ((err = skb_add_data(skb, from, copy)) != 0) 745 goto do_fault; 746 } else { 747 int merge = 0; 748 int i = skb_shinfo(skb)->nr_frags; 749 struct page *page = TCP_PAGE(sk); 750 int off = TCP_OFF(sk); 751 752 if (skb_can_coalesce(skb, i, page, off) && 753 off != PAGE_SIZE) { 754 /* We can extend the last page 755 * fragment. */ 756 merge = 1; 757 } else if (i == MAX_SKB_FRAGS || 758 (!i && 759 !(sk->sk_route_caps & NETIF_F_SG))) { 760 /* Need to add new fragment and cannot 761 * do this because interface is non-SG, 762 * or because all the page slots are 763 * busy. */ 764 tcp_mark_push(tp, skb); 765 goto new_segment; 766 } else if (page) { 767 if (off == PAGE_SIZE) { 768 put_page(page); 769 TCP_PAGE(sk) = page = NULL; 770 off = 0; 771 } 772 } else 773 off = 0; 774 775 if (copy > PAGE_SIZE - off) 776 copy = PAGE_SIZE - off; 777 778 if (!sk_stream_wmem_schedule(sk, copy)) 779 goto wait_for_memory; 780 781 if (!page) { 782 /* Allocate new cache page. */ 783 if (!(page = sk_stream_alloc_page(sk))) 784 goto wait_for_memory; 785 } 786 787 /* Time to copy data. We are close to 788 * the end! */ 789 err = skb_copy_to_page(sk, from, skb, page, 790 off, copy); 791 if (err) { 792 /* If this page was new, give it to the 793 * socket so it does not get leaked. 794 */ 795 if (!TCP_PAGE(sk)) { 796 TCP_PAGE(sk) = page; 797 TCP_OFF(sk) = 0; 798 } 799 goto do_error; 800 } 801 802 /* Update the skb. */ 803 if (merge) { 804 skb_shinfo(skb)->frags[i - 1].size += 805 copy; 806 } else { 807 skb_fill_page_desc(skb, i, page, off, copy); 808 if (TCP_PAGE(sk)) { 809 get_page(page); 810 } else if (off + copy < PAGE_SIZE) { 811 get_page(page); 812 TCP_PAGE(sk) = page; 813 } 814 } 815 816 TCP_OFF(sk) = off + copy; 817 } 818 819 if (!copied) 820 TCP_SKB_CB(skb)->flags &= ~TCPCB_FLAG_PSH; 821 822 tp->write_seq += copy; 823 TCP_SKB_CB(skb)->end_seq += copy; 824 skb_shinfo(skb)->gso_segs = 0; 825 826 from += copy; 827 copied += copy; 828 if ((seglen -= copy) == 0 && iovlen == 0) 829 goto out; 830 831 if (skb->len < mss_now || (flags & MSG_OOB)) 832 continue; 833 834 if (forced_push(tp)) { 835 tcp_mark_push(tp, skb); 836 __tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_PUSH); 837 } else if (skb == tcp_send_head(sk)) 838 tcp_push_one(sk, mss_now); 839 continue; 840 841 wait_for_sndbuf: 842 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags); 843 wait_for_memory: 844 if (copied) 845 tcp_push(sk, flags & ~MSG_MORE, mss_now, TCP_NAGLE_PUSH); 846 847 if ((err = sk_stream_wait_memory(sk, &timeo)) != 0) 848 goto do_error; 849 850 mss_now = tcp_current_mss(sk, !(flags&MSG_OOB)); 851 size_goal = tp->xmit_size_goal; 852 } 853 } 854 855 out: 856 if (copied) 857 tcp_push(sk, flags, mss_now, tp->nonagle); 858 TCP_CHECK_TIMER(sk); 859 release_sock(sk); 860 return copied; 861 862 do_fault: 863 if (!skb->len) { 864 tcp_unlink_write_queue(skb, sk); 865 /* It is the one place in all of TCP, except connection 866 * reset, where we can be unlinking the send_head. 867 */ 868 tcp_check_send_head(sk, skb); 869 sk_stream_free_skb(sk, skb); 870 } 871 872 do_error: 873 if (copied) 874 goto out; 875 out_err: 876 err = sk_stream_error(sk, flags, err); 877 TCP_CHECK_TIMER(sk); 878 release_sock(sk); 879 return err; 880 } 881 882 /* 883 * Handle reading urgent data. BSD has very simple semantics for 884 * this, no blocking and very strange errors 8) 885 */ 886 887 static int tcp_recv_urg(struct sock *sk, long timeo, 888 struct msghdr *msg, int len, int flags, 889 int *addr_len) 890 { 891 struct tcp_sock *tp = tcp_sk(sk); 892 893 /* No URG data to read. */ 894 if (sock_flag(sk, SOCK_URGINLINE) || !tp->urg_data || 895 tp->urg_data == TCP_URG_READ) 896 return -EINVAL; /* Yes this is right ! */ 897 898 if (sk->sk_state == TCP_CLOSE && !sock_flag(sk, SOCK_DONE)) 899 return -ENOTCONN; 900 901 if (tp->urg_data & TCP_URG_VALID) { 902 int err = 0; 903 char c = tp->urg_data; 904 905 if (!(flags & MSG_PEEK)) 906 tp->urg_data = TCP_URG_READ; 907 908 /* Read urgent data. */ 909 msg->msg_flags |= MSG_OOB; 910 911 if (len > 0) { 912 if (!(flags & MSG_TRUNC)) 913 err = memcpy_toiovec(msg->msg_iov, &c, 1); 914 len = 1; 915 } else 916 msg->msg_flags |= MSG_TRUNC; 917 918 return err ? -EFAULT : len; 919 } 920 921 if (sk->sk_state == TCP_CLOSE || (sk->sk_shutdown & RCV_SHUTDOWN)) 922 return 0; 923 924 /* Fixed the recv(..., MSG_OOB) behaviour. BSD docs and 925 * the available implementations agree in this case: 926 * this call should never block, independent of the 927 * blocking state of the socket. 928 * Mike <pall@rz.uni-karlsruhe.de> 929 */ 930 return -EAGAIN; 931 } 932 933 /* Clean up the receive buffer for full frames taken by the user, 934 * then send an ACK if necessary. COPIED is the number of bytes 935 * tcp_recvmsg has given to the user so far, it speeds up the 936 * calculation of whether or not we must ACK for the sake of 937 * a window update. 938 */ 939 void tcp_cleanup_rbuf(struct sock *sk, int copied) 940 { 941 struct tcp_sock *tp = tcp_sk(sk); 942 int time_to_ack = 0; 943 944 #if TCP_DEBUG 945 struct sk_buff *skb = skb_peek(&sk->sk_receive_queue); 946 947 BUG_TRAP(!skb || before(tp->copied_seq, TCP_SKB_CB(skb)->end_seq)); 948 #endif 949 950 if (inet_csk_ack_scheduled(sk)) { 951 const struct inet_connection_sock *icsk = inet_csk(sk); 952 /* Delayed ACKs frequently hit locked sockets during bulk 953 * receive. */ 954 if (icsk->icsk_ack.blocked || 955 /* Once-per-two-segments ACK was not sent by tcp_input.c */ 956 tp->rcv_nxt - tp->rcv_wup > icsk->icsk_ack.rcv_mss || 957 /* 958 * If this read emptied read buffer, we send ACK, if 959 * connection is not bidirectional, user drained 960 * receive buffer and there was a small segment 961 * in queue. 962 */ 963 (copied > 0 && 964 ((icsk->icsk_ack.pending & ICSK_ACK_PUSHED2) || 965 ((icsk->icsk_ack.pending & ICSK_ACK_PUSHED) && 966 !icsk->icsk_ack.pingpong)) && 967 !atomic_read(&sk->sk_rmem_alloc))) 968 time_to_ack = 1; 969 } 970 971 /* We send an ACK if we can now advertise a non-zero window 972 * which has been raised "significantly". 973 * 974 * Even if window raised up to infinity, do not send window open ACK 975 * in states, where we will not receive more. It is useless. 976 */ 977 if (copied > 0 && !time_to_ack && !(sk->sk_shutdown & RCV_SHUTDOWN)) { 978 __u32 rcv_window_now = tcp_receive_window(tp); 979 980 /* Optimize, __tcp_select_window() is not cheap. */ 981 if (2*rcv_window_now <= tp->window_clamp) { 982 __u32 new_window = __tcp_select_window(sk); 983 984 /* Send ACK now, if this read freed lots of space 985 * in our buffer. Certainly, new_window is new window. 986 * We can advertise it now, if it is not less than current one. 987 * "Lots" means "at least twice" here. 988 */ 989 if (new_window && new_window >= 2 * rcv_window_now) 990 time_to_ack = 1; 991 } 992 } 993 if (time_to_ack) 994 tcp_send_ack(sk); 995 } 996 997 static void tcp_prequeue_process(struct sock *sk) 998 { 999 struct sk_buff *skb; 1000 struct tcp_sock *tp = tcp_sk(sk); 1001 1002 NET_INC_STATS_USER(LINUX_MIB_TCPPREQUEUED); 1003 1004 /* RX process wants to run with disabled BHs, though it is not 1005 * necessary */ 1006 local_bh_disable(); 1007 while ((skb = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) 1008 sk->sk_backlog_rcv(sk, skb); 1009 local_bh_enable(); 1010 1011 /* Clear memory counter. */ 1012 tp->ucopy.memory = 0; 1013 } 1014 1015 static inline struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off) 1016 { 1017 struct sk_buff *skb; 1018 u32 offset; 1019 1020 skb_queue_walk(&sk->sk_receive_queue, skb) { 1021 offset = seq - TCP_SKB_CB(skb)->seq; 1022 if (tcp_hdr(skb)->syn) 1023 offset--; 1024 if (offset < skb->len || tcp_hdr(skb)->fin) { 1025 *off = offset; 1026 return skb; 1027 } 1028 } 1029 return NULL; 1030 } 1031 1032 /* 1033 * This routine provides an alternative to tcp_recvmsg() for routines 1034 * that would like to handle copying from skbuffs directly in 'sendfile' 1035 * fashion. 1036 * Note: 1037 * - It is assumed that the socket was locked by the caller. 1038 * - The routine does not block. 1039 * - At present, there is no support for reading OOB data 1040 * or for 'peeking' the socket using this routine 1041 * (although both would be easy to implement). 1042 */ 1043 int tcp_read_sock(struct sock *sk, read_descriptor_t *desc, 1044 sk_read_actor_t recv_actor) 1045 { 1046 struct sk_buff *skb; 1047 struct tcp_sock *tp = tcp_sk(sk); 1048 u32 seq = tp->copied_seq; 1049 u32 offset; 1050 int copied = 0; 1051 1052 if (sk->sk_state == TCP_LISTEN) 1053 return -ENOTCONN; 1054 while ((skb = tcp_recv_skb(sk, seq, &offset)) != NULL) { 1055 if (offset < skb->len) { 1056 size_t used, len; 1057 1058 len = skb->len - offset; 1059 /* Stop reading if we hit a patch of urgent data */ 1060 if (tp->urg_data) { 1061 u32 urg_offset = tp->urg_seq - seq; 1062 if (urg_offset < len) 1063 len = urg_offset; 1064 if (!len) 1065 break; 1066 } 1067 used = recv_actor(desc, skb, offset, len); 1068 if (used <= len) { 1069 seq += used; 1070 copied += used; 1071 offset += used; 1072 } 1073 if (offset != skb->len) 1074 break; 1075 } 1076 if (tcp_hdr(skb)->fin) { 1077 sk_eat_skb(sk, skb, 0); 1078 ++seq; 1079 break; 1080 } 1081 sk_eat_skb(sk, skb, 0); 1082 if (!desc->count) 1083 break; 1084 } 1085 tp->copied_seq = seq; 1086 1087 tcp_rcv_space_adjust(sk); 1088 1089 /* Clean up data we have read: This will do ACK frames. */ 1090 if (copied) 1091 tcp_cleanup_rbuf(sk, copied); 1092 return copied; 1093 } 1094 1095 /* 1096 * This routine copies from a sock struct into the user buffer. 1097 * 1098 * Technical note: in 2.3 we work on _locked_ socket, so that 1099 * tricks with *seq access order and skb->users are not required. 1100 * Probably, code can be easily improved even more. 1101 */ 1102 1103 int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, 1104 size_t len, int nonblock, int flags, int *addr_len) 1105 { 1106 struct tcp_sock *tp = tcp_sk(sk); 1107 int copied = 0; 1108 u32 peek_seq; 1109 u32 *seq; 1110 unsigned long used; 1111 int err; 1112 int target; /* Read at least this many bytes */ 1113 long timeo; 1114 struct task_struct *user_recv = NULL; 1115 int copied_early = 0; 1116 1117 lock_sock(sk); 1118 1119 TCP_CHECK_TIMER(sk); 1120 1121 err = -ENOTCONN; 1122 if (sk->sk_state == TCP_LISTEN) 1123 goto out; 1124 1125 timeo = sock_rcvtimeo(sk, nonblock); 1126 1127 /* Urgent data needs to be handled specially. */ 1128 if (flags & MSG_OOB) 1129 goto recv_urg; 1130 1131 seq = &tp->copied_seq; 1132 if (flags & MSG_PEEK) { 1133 peek_seq = tp->copied_seq; 1134 seq = &peek_seq; 1135 } 1136 1137 target = sock_rcvlowat(sk, flags & MSG_WAITALL, len); 1138 1139 #ifdef CONFIG_NET_DMA 1140 tp->ucopy.dma_chan = NULL; 1141 preempt_disable(); 1142 if ((len > sysctl_tcp_dma_copybreak) && !(flags & MSG_PEEK) && 1143 !sysctl_tcp_low_latency && __get_cpu_var(softnet_data).net_dma) { 1144 preempt_enable_no_resched(); 1145 tp->ucopy.pinned_list = dma_pin_iovec_pages(msg->msg_iov, len); 1146 } else 1147 preempt_enable_no_resched(); 1148 #endif 1149 1150 do { 1151 struct sk_buff *skb; 1152 u32 offset; 1153 1154 /* Are we at urgent data? Stop if we have read anything or have SIGURG pending. */ 1155 if (tp->urg_data && tp->urg_seq == *seq) { 1156 if (copied) 1157 break; 1158 if (signal_pending(current)) { 1159 copied = timeo ? sock_intr_errno(timeo) : -EAGAIN; 1160 break; 1161 } 1162 } 1163 1164 /* Next get a buffer. */ 1165 1166 skb = skb_peek(&sk->sk_receive_queue); 1167 do { 1168 if (!skb) 1169 break; 1170 1171 /* Now that we have two receive queues this 1172 * shouldn't happen. 1173 */ 1174 if (before(*seq, TCP_SKB_CB(skb)->seq)) { 1175 printk(KERN_INFO "recvmsg bug: copied %X " 1176 "seq %X\n", *seq, TCP_SKB_CB(skb)->seq); 1177 break; 1178 } 1179 offset = *seq - TCP_SKB_CB(skb)->seq; 1180 if (tcp_hdr(skb)->syn) 1181 offset--; 1182 if (offset < skb->len) 1183 goto found_ok_skb; 1184 if (tcp_hdr(skb)->fin) 1185 goto found_fin_ok; 1186 BUG_TRAP(flags & MSG_PEEK); 1187 skb = skb->next; 1188 } while (skb != (struct sk_buff *)&sk->sk_receive_queue); 1189 1190 /* Well, if we have backlog, try to process it now yet. */ 1191 1192 if (copied >= target && !sk->sk_backlog.tail) 1193 break; 1194 1195 if (copied) { 1196 if (sk->sk_err || 1197 sk->sk_state == TCP_CLOSE || 1198 (sk->sk_shutdown & RCV_SHUTDOWN) || 1199 !timeo || 1200 signal_pending(current) || 1201 (flags & MSG_PEEK)) 1202 break; 1203 } else { 1204 if (sock_flag(sk, SOCK_DONE)) 1205 break; 1206 1207 if (sk->sk_err) { 1208 copied = sock_error(sk); 1209 break; 1210 } 1211 1212 if (sk->sk_shutdown & RCV_SHUTDOWN) 1213 break; 1214 1215 if (sk->sk_state == TCP_CLOSE) { 1216 if (!sock_flag(sk, SOCK_DONE)) { 1217 /* This occurs when user tries to read 1218 * from never connected socket. 1219 */ 1220 copied = -ENOTCONN; 1221 break; 1222 } 1223 break; 1224 } 1225 1226 if (!timeo) { 1227 copied = -EAGAIN; 1228 break; 1229 } 1230 1231 if (signal_pending(current)) { 1232 copied = sock_intr_errno(timeo); 1233 break; 1234 } 1235 } 1236 1237 tcp_cleanup_rbuf(sk, copied); 1238 1239 if (!sysctl_tcp_low_latency && tp->ucopy.task == user_recv) { 1240 /* Install new reader */ 1241 if (!user_recv && !(flags & (MSG_TRUNC | MSG_PEEK))) { 1242 user_recv = current; 1243 tp->ucopy.task = user_recv; 1244 tp->ucopy.iov = msg->msg_iov; 1245 } 1246 1247 tp->ucopy.len = len; 1248 1249 BUG_TRAP(tp->copied_seq == tp->rcv_nxt || 1250 (flags & (MSG_PEEK | MSG_TRUNC))); 1251 1252 /* Ugly... If prequeue is not empty, we have to 1253 * process it before releasing socket, otherwise 1254 * order will be broken at second iteration. 1255 * More elegant solution is required!!! 1256 * 1257 * Look: we have the following (pseudo)queues: 1258 * 1259 * 1. packets in flight 1260 * 2. backlog 1261 * 3. prequeue 1262 * 4. receive_queue 1263 * 1264 * Each queue can be processed only if the next ones 1265 * are empty. At this point we have empty receive_queue. 1266 * But prequeue _can_ be not empty after 2nd iteration, 1267 * when we jumped to start of loop because backlog 1268 * processing added something to receive_queue. 1269 * We cannot release_sock(), because backlog contains 1270 * packets arrived _after_ prequeued ones. 1271 * 1272 * Shortly, algorithm is clear --- to process all 1273 * the queues in order. We could make it more directly, 1274 * requeueing packets from backlog to prequeue, if 1275 * is not empty. It is more elegant, but eats cycles, 1276 * unfortunately. 1277 */ 1278 if (!skb_queue_empty(&tp->ucopy.prequeue)) 1279 goto do_prequeue; 1280 1281 /* __ Set realtime policy in scheduler __ */ 1282 } 1283 1284 if (copied >= target) { 1285 /* Do not sleep, just process backlog. */ 1286 release_sock(sk); 1287 lock_sock(sk); 1288 } else 1289 sk_wait_data(sk, &timeo); 1290 1291 #ifdef CONFIG_NET_DMA 1292 tp->ucopy.wakeup = 0; 1293 #endif 1294 1295 if (user_recv) { 1296 int chunk; 1297 1298 /* __ Restore normal policy in scheduler __ */ 1299 1300 if ((chunk = len - tp->ucopy.len) != 0) { 1301 NET_ADD_STATS_USER(LINUX_MIB_TCPDIRECTCOPYFROMBACKLOG, chunk); 1302 len -= chunk; 1303 copied += chunk; 1304 } 1305 1306 if (tp->rcv_nxt == tp->copied_seq && 1307 !skb_queue_empty(&tp->ucopy.prequeue)) { 1308 do_prequeue: 1309 tcp_prequeue_process(sk); 1310 1311 if ((chunk = len - tp->ucopy.len) != 0) { 1312 NET_ADD_STATS_USER(LINUX_MIB_TCPDIRECTCOPYFROMPREQUEUE, chunk); 1313 len -= chunk; 1314 copied += chunk; 1315 } 1316 } 1317 } 1318 if ((flags & MSG_PEEK) && peek_seq != tp->copied_seq) { 1319 if (net_ratelimit()) 1320 printk(KERN_DEBUG "TCP(%s:%d): Application bug, race in MSG_PEEK.\n", 1321 current->comm, current->pid); 1322 peek_seq = tp->copied_seq; 1323 } 1324 continue; 1325 1326 found_ok_skb: 1327 /* Ok so how much can we use? */ 1328 used = skb->len - offset; 1329 if (len < used) 1330 used = len; 1331 1332 /* Do we have urgent data here? */ 1333 if (tp->urg_data) { 1334 u32 urg_offset = tp->urg_seq - *seq; 1335 if (urg_offset < used) { 1336 if (!urg_offset) { 1337 if (!sock_flag(sk, SOCK_URGINLINE)) { 1338 ++*seq; 1339 offset++; 1340 used--; 1341 if (!used) 1342 goto skip_copy; 1343 } 1344 } else 1345 used = urg_offset; 1346 } 1347 } 1348 1349 if (!(flags & MSG_TRUNC)) { 1350 #ifdef CONFIG_NET_DMA 1351 if (!tp->ucopy.dma_chan && tp->ucopy.pinned_list) 1352 tp->ucopy.dma_chan = get_softnet_dma(); 1353 1354 if (tp->ucopy.dma_chan) { 1355 tp->ucopy.dma_cookie = dma_skb_copy_datagram_iovec( 1356 tp->ucopy.dma_chan, skb, offset, 1357 msg->msg_iov, used, 1358 tp->ucopy.pinned_list); 1359 1360 if (tp->ucopy.dma_cookie < 0) { 1361 1362 printk(KERN_ALERT "dma_cookie < 0\n"); 1363 1364 /* Exception. Bailout! */ 1365 if (!copied) 1366 copied = -EFAULT; 1367 break; 1368 } 1369 if ((offset + used) == skb->len) 1370 copied_early = 1; 1371 1372 } else 1373 #endif 1374 { 1375 err = skb_copy_datagram_iovec(skb, offset, 1376 msg->msg_iov, used); 1377 if (err) { 1378 /* Exception. Bailout! */ 1379 if (!copied) 1380 copied = -EFAULT; 1381 break; 1382 } 1383 } 1384 } 1385 1386 *seq += used; 1387 copied += used; 1388 len -= used; 1389 1390 tcp_rcv_space_adjust(sk); 1391 1392 skip_copy: 1393 if (tp->urg_data && after(tp->copied_seq, tp->urg_seq)) { 1394 tp->urg_data = 0; 1395 tcp_fast_path_check(sk); 1396 } 1397 if (used + offset < skb->len) 1398 continue; 1399 1400 if (tcp_hdr(skb)->fin) 1401 goto found_fin_ok; 1402 if (!(flags & MSG_PEEK)) { 1403 sk_eat_skb(sk, skb, copied_early); 1404 copied_early = 0; 1405 } 1406 continue; 1407 1408 found_fin_ok: 1409 /* Process the FIN. */ 1410 ++*seq; 1411 if (!(flags & MSG_PEEK)) { 1412 sk_eat_skb(sk, skb, copied_early); 1413 copied_early = 0; 1414 } 1415 break; 1416 } while (len > 0); 1417 1418 if (user_recv) { 1419 if (!skb_queue_empty(&tp->ucopy.prequeue)) { 1420 int chunk; 1421 1422 tp->ucopy.len = copied > 0 ? len : 0; 1423 1424 tcp_prequeue_process(sk); 1425 1426 if (copied > 0 && (chunk = len - tp->ucopy.len) != 0) { 1427 NET_ADD_STATS_USER(LINUX_MIB_TCPDIRECTCOPYFROMPREQUEUE, chunk); 1428 len -= chunk; 1429 copied += chunk; 1430 } 1431 } 1432 1433 tp->ucopy.task = NULL; 1434 tp->ucopy.len = 0; 1435 } 1436 1437 #ifdef CONFIG_NET_DMA 1438 if (tp->ucopy.dma_chan) { 1439 struct sk_buff *skb; 1440 dma_cookie_t done, used; 1441 1442 dma_async_memcpy_issue_pending(tp->ucopy.dma_chan); 1443 1444 while (dma_async_memcpy_complete(tp->ucopy.dma_chan, 1445 tp->ucopy.dma_cookie, &done, 1446 &used) == DMA_IN_PROGRESS) { 1447 /* do partial cleanup of sk_async_wait_queue */ 1448 while ((skb = skb_peek(&sk->sk_async_wait_queue)) && 1449 (dma_async_is_complete(skb->dma_cookie, done, 1450 used) == DMA_SUCCESS)) { 1451 __skb_dequeue(&sk->sk_async_wait_queue); 1452 kfree_skb(skb); 1453 } 1454 } 1455 1456 /* Safe to free early-copied skbs now */ 1457 __skb_queue_purge(&sk->sk_async_wait_queue); 1458 dma_chan_put(tp->ucopy.dma_chan); 1459 tp->ucopy.dma_chan = NULL; 1460 } 1461 if (tp->ucopy.pinned_list) { 1462 dma_unpin_iovec_pages(tp->ucopy.pinned_list); 1463 tp->ucopy.pinned_list = NULL; 1464 } 1465 #endif 1466 1467 /* According to UNIX98, msg_name/msg_namelen are ignored 1468 * on connected socket. I was just happy when found this 8) --ANK 1469 */ 1470 1471 /* Clean up data we have read: This will do ACK frames. */ 1472 tcp_cleanup_rbuf(sk, copied); 1473 1474 TCP_CHECK_TIMER(sk); 1475 release_sock(sk); 1476 return copied; 1477 1478 out: 1479 TCP_CHECK_TIMER(sk); 1480 release_sock(sk); 1481 return err; 1482 1483 recv_urg: 1484 err = tcp_recv_urg(sk, timeo, msg, len, flags, addr_len); 1485 goto out; 1486 } 1487 1488 /* 1489 * State processing on a close. This implements the state shift for 1490 * sending our FIN frame. Note that we only send a FIN for some 1491 * states. A shutdown() may have already sent the FIN, or we may be 1492 * closed. 1493 */ 1494 1495 static const unsigned char new_state[16] = { 1496 /* current state: new state: action: */ 1497 /* (Invalid) */ TCP_CLOSE, 1498 /* TCP_ESTABLISHED */ TCP_FIN_WAIT1 | TCP_ACTION_FIN, 1499 /* TCP_SYN_SENT */ TCP_CLOSE, 1500 /* TCP_SYN_RECV */ TCP_FIN_WAIT1 | TCP_ACTION_FIN, 1501 /* TCP_FIN_WAIT1 */ TCP_FIN_WAIT1, 1502 /* TCP_FIN_WAIT2 */ TCP_FIN_WAIT2, 1503 /* TCP_TIME_WAIT */ TCP_CLOSE, 1504 /* TCP_CLOSE */ TCP_CLOSE, 1505 /* TCP_CLOSE_WAIT */ TCP_LAST_ACK | TCP_ACTION_FIN, 1506 /* TCP_LAST_ACK */ TCP_LAST_ACK, 1507 /* TCP_LISTEN */ TCP_CLOSE, 1508 /* TCP_CLOSING */ TCP_CLOSING, 1509 }; 1510 1511 static int tcp_close_state(struct sock *sk) 1512 { 1513 int next = (int)new_state[sk->sk_state]; 1514 int ns = next & TCP_STATE_MASK; 1515 1516 tcp_set_state(sk, ns); 1517 1518 return next & TCP_ACTION_FIN; 1519 } 1520 1521 /* 1522 * Shutdown the sending side of a connection. Much like close except 1523 * that we don't receive shut down or set_sock_flag(sk, SOCK_DEAD). 1524 */ 1525 1526 void tcp_shutdown(struct sock *sk, int how) 1527 { 1528 /* We need to grab some memory, and put together a FIN, 1529 * and then put it into the queue to be sent. 1530 * Tim MacKenzie(tym@dibbler.cs.monash.edu.au) 4 Dec '92. 1531 */ 1532 if (!(how & SEND_SHUTDOWN)) 1533 return; 1534 1535 /* If we've already sent a FIN, or it's a closed state, skip this. */ 1536 if ((1 << sk->sk_state) & 1537 (TCPF_ESTABLISHED | TCPF_SYN_SENT | 1538 TCPF_SYN_RECV | TCPF_CLOSE_WAIT)) { 1539 /* Clear out any half completed packets. FIN if needed. */ 1540 if (tcp_close_state(sk)) 1541 tcp_send_fin(sk); 1542 } 1543 } 1544 1545 void tcp_close(struct sock *sk, long timeout) 1546 { 1547 struct sk_buff *skb; 1548 int data_was_unread = 0; 1549 int state; 1550 1551 lock_sock(sk); 1552 sk->sk_shutdown = SHUTDOWN_MASK; 1553 1554 if (sk->sk_state == TCP_LISTEN) { 1555 tcp_set_state(sk, TCP_CLOSE); 1556 1557 /* Special case. */ 1558 inet_csk_listen_stop(sk); 1559 1560 goto adjudge_to_death; 1561 } 1562 1563 /* We need to flush the recv. buffs. We do this only on the 1564 * descriptor close, not protocol-sourced closes, because the 1565 * reader process may not have drained the data yet! 1566 */ 1567 while ((skb = __skb_dequeue(&sk->sk_receive_queue)) != NULL) { 1568 u32 len = TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq - 1569 tcp_hdr(skb)->fin; 1570 data_was_unread += len; 1571 __kfree_skb(skb); 1572 } 1573 1574 sk_stream_mem_reclaim(sk); 1575 1576 /* As outlined in RFC 2525, section 2.17, we send a RST here because 1577 * data was lost. To witness the awful effects of the old behavior of 1578 * always doing a FIN, run an older 2.1.x kernel or 2.0.x, start a bulk 1579 * GET in an FTP client, suspend the process, wait for the client to 1580 * advertise a zero window, then kill -9 the FTP client, wheee... 1581 * Note: timeout is always zero in such a case. 1582 */ 1583 if (data_was_unread) { 1584 /* Unread data was tossed, zap the connection. */ 1585 NET_INC_STATS_USER(LINUX_MIB_TCPABORTONCLOSE); 1586 tcp_set_state(sk, TCP_CLOSE); 1587 tcp_send_active_reset(sk, GFP_KERNEL); 1588 } else if (sock_flag(sk, SOCK_LINGER) && !sk->sk_lingertime) { 1589 /* Check zero linger _after_ checking for unread data. */ 1590 sk->sk_prot->disconnect(sk, 0); 1591 NET_INC_STATS_USER(LINUX_MIB_TCPABORTONDATA); 1592 } else if (tcp_close_state(sk)) { 1593 /* We FIN if the application ate all the data before 1594 * zapping the connection. 1595 */ 1596 1597 /* RED-PEN. Formally speaking, we have broken TCP state 1598 * machine. State transitions: 1599 * 1600 * TCP_ESTABLISHED -> TCP_FIN_WAIT1 1601 * TCP_SYN_RECV -> TCP_FIN_WAIT1 (forget it, it's impossible) 1602 * TCP_CLOSE_WAIT -> TCP_LAST_ACK 1603 * 1604 * are legal only when FIN has been sent (i.e. in window), 1605 * rather than queued out of window. Purists blame. 1606 * 1607 * F.e. "RFC state" is ESTABLISHED, 1608 * if Linux state is FIN-WAIT-1, but FIN is still not sent. 1609 * 1610 * The visible declinations are that sometimes 1611 * we enter time-wait state, when it is not required really 1612 * (harmless), do not send active resets, when they are 1613 * required by specs (TCP_ESTABLISHED, TCP_CLOSE_WAIT, when 1614 * they look as CLOSING or LAST_ACK for Linux) 1615 * Probably, I missed some more holelets. 1616 * --ANK 1617 */ 1618 tcp_send_fin(sk); 1619 } 1620 1621 sk_stream_wait_close(sk, timeout); 1622 1623 adjudge_to_death: 1624 state = sk->sk_state; 1625 sock_hold(sk); 1626 sock_orphan(sk); 1627 atomic_inc(sk->sk_prot->orphan_count); 1628 1629 /* It is the last release_sock in its life. It will remove backlog. */ 1630 release_sock(sk); 1631 1632 1633 /* Now socket is owned by kernel and we acquire BH lock 1634 to finish close. No need to check for user refs. 1635 */ 1636 local_bh_disable(); 1637 bh_lock_sock(sk); 1638 BUG_TRAP(!sock_owned_by_user(sk)); 1639 1640 /* Have we already been destroyed by a softirq or backlog? */ 1641 if (state != TCP_CLOSE && sk->sk_state == TCP_CLOSE) 1642 goto out; 1643 1644 /* This is a (useful) BSD violating of the RFC. There is a 1645 * problem with TCP as specified in that the other end could 1646 * keep a socket open forever with no application left this end. 1647 * We use a 3 minute timeout (about the same as BSD) then kill 1648 * our end. If they send after that then tough - BUT: long enough 1649 * that we won't make the old 4*rto = almost no time - whoops 1650 * reset mistake. 1651 * 1652 * Nope, it was not mistake. It is really desired behaviour 1653 * f.e. on http servers, when such sockets are useless, but 1654 * consume significant resources. Let's do it with special 1655 * linger2 option. --ANK 1656 */ 1657 1658 if (sk->sk_state == TCP_FIN_WAIT2) { 1659 struct tcp_sock *tp = tcp_sk(sk); 1660 if (tp->linger2 < 0) { 1661 tcp_set_state(sk, TCP_CLOSE); 1662 tcp_send_active_reset(sk, GFP_ATOMIC); 1663 NET_INC_STATS_BH(LINUX_MIB_TCPABORTONLINGER); 1664 } else { 1665 const int tmo = tcp_fin_time(sk); 1666 1667 if (tmo > TCP_TIMEWAIT_LEN) { 1668 inet_csk_reset_keepalive_timer(sk, 1669 tmo - TCP_TIMEWAIT_LEN); 1670 } else { 1671 tcp_time_wait(sk, TCP_FIN_WAIT2, tmo); 1672 goto out; 1673 } 1674 } 1675 } 1676 if (sk->sk_state != TCP_CLOSE) { 1677 sk_stream_mem_reclaim(sk); 1678 if (atomic_read(sk->sk_prot->orphan_count) > sysctl_tcp_max_orphans || 1679 (sk->sk_wmem_queued > SOCK_MIN_SNDBUF && 1680 atomic_read(&tcp_memory_allocated) > sysctl_tcp_mem[2])) { 1681 if (net_ratelimit()) 1682 printk(KERN_INFO "TCP: too many of orphaned " 1683 "sockets\n"); 1684 tcp_set_state(sk, TCP_CLOSE); 1685 tcp_send_active_reset(sk, GFP_ATOMIC); 1686 NET_INC_STATS_BH(LINUX_MIB_TCPABORTONMEMORY); 1687 } 1688 } 1689 1690 if (sk->sk_state == TCP_CLOSE) 1691 inet_csk_destroy_sock(sk); 1692 /* Otherwise, socket is reprieved until protocol close. */ 1693 1694 out: 1695 bh_unlock_sock(sk); 1696 local_bh_enable(); 1697 sock_put(sk); 1698 } 1699 1700 /* These states need RST on ABORT according to RFC793 */ 1701 1702 static inline int tcp_need_reset(int state) 1703 { 1704 return (1 << state) & 1705 (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT | TCPF_FIN_WAIT1 | 1706 TCPF_FIN_WAIT2 | TCPF_SYN_RECV); 1707 } 1708 1709 int tcp_disconnect(struct sock *sk, int flags) 1710 { 1711 struct inet_sock *inet = inet_sk(sk); 1712 struct inet_connection_sock *icsk = inet_csk(sk); 1713 struct tcp_sock *tp = tcp_sk(sk); 1714 int err = 0; 1715 int old_state = sk->sk_state; 1716 1717 if (old_state != TCP_CLOSE) 1718 tcp_set_state(sk, TCP_CLOSE); 1719 1720 /* ABORT function of RFC793 */ 1721 if (old_state == TCP_LISTEN) { 1722 inet_csk_listen_stop(sk); 1723 } else if (tcp_need_reset(old_state) || 1724 (tp->snd_nxt != tp->write_seq && 1725 (1 << old_state) & (TCPF_CLOSING | TCPF_LAST_ACK))) { 1726 /* The last check adjusts for discrepancy of Linux wrt. RFC 1727 * states 1728 */ 1729 tcp_send_active_reset(sk, gfp_any()); 1730 sk->sk_err = ECONNRESET; 1731 } else if (old_state == TCP_SYN_SENT) 1732 sk->sk_err = ECONNRESET; 1733 1734 tcp_clear_xmit_timers(sk); 1735 __skb_queue_purge(&sk->sk_receive_queue); 1736 tcp_write_queue_purge(sk); 1737 __skb_queue_purge(&tp->out_of_order_queue); 1738 #ifdef CONFIG_NET_DMA 1739 __skb_queue_purge(&sk->sk_async_wait_queue); 1740 #endif 1741 1742 inet->dport = 0; 1743 1744 if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK)) 1745 inet_reset_saddr(sk); 1746 1747 sk->sk_shutdown = 0; 1748 sock_reset_flag(sk, SOCK_DONE); 1749 tp->srtt = 0; 1750 if ((tp->write_seq += tp->max_window + 2) == 0) 1751 tp->write_seq = 1; 1752 icsk->icsk_backoff = 0; 1753 tp->snd_cwnd = 2; 1754 icsk->icsk_probes_out = 0; 1755 tp->packets_out = 0; 1756 tp->snd_ssthresh = 0x7fffffff; 1757 tp->snd_cwnd_cnt = 0; 1758 tp->bytes_acked = 0; 1759 tcp_set_ca_state(sk, TCP_CA_Open); 1760 tcp_clear_retrans(tp); 1761 inet_csk_delack_init(sk); 1762 tcp_init_send_head(sk); 1763 memset(&tp->rx_opt, 0, sizeof(tp->rx_opt)); 1764 __sk_dst_reset(sk); 1765 1766 BUG_TRAP(!inet->num || icsk->icsk_bind_hash); 1767 1768 sk->sk_error_report(sk); 1769 return err; 1770 } 1771 1772 /* 1773 * Socket option code for TCP. 1774 */ 1775 static int do_tcp_setsockopt(struct sock *sk, int level, 1776 int optname, char __user *optval, int optlen) 1777 { 1778 struct tcp_sock *tp = tcp_sk(sk); 1779 struct inet_connection_sock *icsk = inet_csk(sk); 1780 int val; 1781 int err = 0; 1782 1783 /* This is a string value all the others are int's */ 1784 if (optname == TCP_CONGESTION) { 1785 char name[TCP_CA_NAME_MAX]; 1786 1787 if (optlen < 1) 1788 return -EINVAL; 1789 1790 val = strncpy_from_user(name, optval, 1791 min(TCP_CA_NAME_MAX-1, optlen)); 1792 if (val < 0) 1793 return -EFAULT; 1794 name[val] = 0; 1795 1796 lock_sock(sk); 1797 err = tcp_set_congestion_control(sk, name); 1798 release_sock(sk); 1799 return err; 1800 } 1801 1802 if (optlen < sizeof(int)) 1803 return -EINVAL; 1804 1805 if (get_user(val, (int __user *)optval)) 1806 return -EFAULT; 1807 1808 lock_sock(sk); 1809 1810 switch (optname) { 1811 case TCP_MAXSEG: 1812 /* Values greater than interface MTU won't take effect. However 1813 * at the point when this call is done we typically don't yet 1814 * know which interface is going to be used */ 1815 if (val < 8 || val > MAX_TCP_WINDOW) { 1816 err = -EINVAL; 1817 break; 1818 } 1819 tp->rx_opt.user_mss = val; 1820 break; 1821 1822 case TCP_NODELAY: 1823 if (val) { 1824 /* TCP_NODELAY is weaker than TCP_CORK, so that 1825 * this option on corked socket is remembered, but 1826 * it is not activated until cork is cleared. 1827 * 1828 * However, when TCP_NODELAY is set we make 1829 * an explicit push, which overrides even TCP_CORK 1830 * for currently queued segments. 1831 */ 1832 tp->nonagle |= TCP_NAGLE_OFF|TCP_NAGLE_PUSH; 1833 tcp_push_pending_frames(sk); 1834 } else { 1835 tp->nonagle &= ~TCP_NAGLE_OFF; 1836 } 1837 break; 1838 1839 case TCP_CORK: 1840 /* When set indicates to always queue non-full frames. 1841 * Later the user clears this option and we transmit 1842 * any pending partial frames in the queue. This is 1843 * meant to be used alongside sendfile() to get properly 1844 * filled frames when the user (for example) must write 1845 * out headers with a write() call first and then use 1846 * sendfile to send out the data parts. 1847 * 1848 * TCP_CORK can be set together with TCP_NODELAY and it is 1849 * stronger than TCP_NODELAY. 1850 */ 1851 if (val) { 1852 tp->nonagle |= TCP_NAGLE_CORK; 1853 } else { 1854 tp->nonagle &= ~TCP_NAGLE_CORK; 1855 if (tp->nonagle&TCP_NAGLE_OFF) 1856 tp->nonagle |= TCP_NAGLE_PUSH; 1857 tcp_push_pending_frames(sk); 1858 } 1859 break; 1860 1861 case TCP_KEEPIDLE: 1862 if (val < 1 || val > MAX_TCP_KEEPIDLE) 1863 err = -EINVAL; 1864 else { 1865 tp->keepalive_time = val * HZ; 1866 if (sock_flag(sk, SOCK_KEEPOPEN) && 1867 !((1 << sk->sk_state) & 1868 (TCPF_CLOSE | TCPF_LISTEN))) { 1869 __u32 elapsed = tcp_time_stamp - tp->rcv_tstamp; 1870 if (tp->keepalive_time > elapsed) 1871 elapsed = tp->keepalive_time - elapsed; 1872 else 1873 elapsed = 0; 1874 inet_csk_reset_keepalive_timer(sk, elapsed); 1875 } 1876 } 1877 break; 1878 case TCP_KEEPINTVL: 1879 if (val < 1 || val > MAX_TCP_KEEPINTVL) 1880 err = -EINVAL; 1881 else 1882 tp->keepalive_intvl = val * HZ; 1883 break; 1884 case TCP_KEEPCNT: 1885 if (val < 1 || val > MAX_TCP_KEEPCNT) 1886 err = -EINVAL; 1887 else 1888 tp->keepalive_probes = val; 1889 break; 1890 case TCP_SYNCNT: 1891 if (val < 1 || val > MAX_TCP_SYNCNT) 1892 err = -EINVAL; 1893 else 1894 icsk->icsk_syn_retries = val; 1895 break; 1896 1897 case TCP_LINGER2: 1898 if (val < 0) 1899 tp->linger2 = -1; 1900 else if (val > sysctl_tcp_fin_timeout / HZ) 1901 tp->linger2 = 0; 1902 else 1903 tp->linger2 = val * HZ; 1904 break; 1905 1906 case TCP_DEFER_ACCEPT: 1907 icsk->icsk_accept_queue.rskq_defer_accept = 0; 1908 if (val > 0) { 1909 /* Translate value in seconds to number of 1910 * retransmits */ 1911 while (icsk->icsk_accept_queue.rskq_defer_accept < 32 && 1912 val > ((TCP_TIMEOUT_INIT / HZ) << 1913 icsk->icsk_accept_queue.rskq_defer_accept)) 1914 icsk->icsk_accept_queue.rskq_defer_accept++; 1915 icsk->icsk_accept_queue.rskq_defer_accept++; 1916 } 1917 break; 1918 1919 case TCP_WINDOW_CLAMP: 1920 if (!val) { 1921 if (sk->sk_state != TCP_CLOSE) { 1922 err = -EINVAL; 1923 break; 1924 } 1925 tp->window_clamp = 0; 1926 } else 1927 tp->window_clamp = val < SOCK_MIN_RCVBUF / 2 ? 1928 SOCK_MIN_RCVBUF / 2 : val; 1929 break; 1930 1931 case TCP_QUICKACK: 1932 if (!val) { 1933 icsk->icsk_ack.pingpong = 1; 1934 } else { 1935 icsk->icsk_ack.pingpong = 0; 1936 if ((1 << sk->sk_state) & 1937 (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT) && 1938 inet_csk_ack_scheduled(sk)) { 1939 icsk->icsk_ack.pending |= ICSK_ACK_PUSHED; 1940 tcp_cleanup_rbuf(sk, 1); 1941 if (!(val & 1)) 1942 icsk->icsk_ack.pingpong = 1; 1943 } 1944 } 1945 break; 1946 1947 #ifdef CONFIG_TCP_MD5SIG 1948 case TCP_MD5SIG: 1949 /* Read the IP->Key mappings from userspace */ 1950 err = tp->af_specific->md5_parse(sk, optval, optlen); 1951 break; 1952 #endif 1953 1954 default: 1955 err = -ENOPROTOOPT; 1956 break; 1957 } 1958 1959 release_sock(sk); 1960 return err; 1961 } 1962 1963 int tcp_setsockopt(struct sock *sk, int level, int optname, char __user *optval, 1964 int optlen) 1965 { 1966 struct inet_connection_sock *icsk = inet_csk(sk); 1967 1968 if (level != SOL_TCP) 1969 return icsk->icsk_af_ops->setsockopt(sk, level, optname, 1970 optval, optlen); 1971 return do_tcp_setsockopt(sk, level, optname, optval, optlen); 1972 } 1973 1974 #ifdef CONFIG_COMPAT 1975 int compat_tcp_setsockopt(struct sock *sk, int level, int optname, 1976 char __user *optval, int optlen) 1977 { 1978 if (level != SOL_TCP) 1979 return inet_csk_compat_setsockopt(sk, level, optname, 1980 optval, optlen); 1981 return do_tcp_setsockopt(sk, level, optname, optval, optlen); 1982 } 1983 1984 EXPORT_SYMBOL(compat_tcp_setsockopt); 1985 #endif 1986 1987 /* Return information about state of tcp endpoint in API format. */ 1988 void tcp_get_info(struct sock *sk, struct tcp_info *info) 1989 { 1990 struct tcp_sock *tp = tcp_sk(sk); 1991 const struct inet_connection_sock *icsk = inet_csk(sk); 1992 u32 now = tcp_time_stamp; 1993 1994 memset(info, 0, sizeof(*info)); 1995 1996 info->tcpi_state = sk->sk_state; 1997 info->tcpi_ca_state = icsk->icsk_ca_state; 1998 info->tcpi_retransmits = icsk->icsk_retransmits; 1999 info->tcpi_probes = icsk->icsk_probes_out; 2000 info->tcpi_backoff = icsk->icsk_backoff; 2001 2002 if (tp->rx_opt.tstamp_ok) 2003 info->tcpi_options |= TCPI_OPT_TIMESTAMPS; 2004 if (tp->rx_opt.sack_ok) 2005 info->tcpi_options |= TCPI_OPT_SACK; 2006 if (tp->rx_opt.wscale_ok) { 2007 info->tcpi_options |= TCPI_OPT_WSCALE; 2008 info->tcpi_snd_wscale = tp->rx_opt.snd_wscale; 2009 info->tcpi_rcv_wscale = tp->rx_opt.rcv_wscale; 2010 } 2011 2012 if (tp->ecn_flags&TCP_ECN_OK) 2013 info->tcpi_options |= TCPI_OPT_ECN; 2014 2015 info->tcpi_rto = jiffies_to_usecs(icsk->icsk_rto); 2016 info->tcpi_ato = jiffies_to_usecs(icsk->icsk_ack.ato); 2017 info->tcpi_snd_mss = tp->mss_cache; 2018 info->tcpi_rcv_mss = icsk->icsk_ack.rcv_mss; 2019 2020 info->tcpi_unacked = tp->packets_out; 2021 info->tcpi_sacked = tp->sacked_out; 2022 info->tcpi_lost = tp->lost_out; 2023 info->tcpi_retrans = tp->retrans_out; 2024 info->tcpi_fackets = tp->fackets_out; 2025 2026 info->tcpi_last_data_sent = jiffies_to_msecs(now - tp->lsndtime); 2027 info->tcpi_last_data_recv = jiffies_to_msecs(now - icsk->icsk_ack.lrcvtime); 2028 info->tcpi_last_ack_recv = jiffies_to_msecs(now - tp->rcv_tstamp); 2029 2030 info->tcpi_pmtu = icsk->icsk_pmtu_cookie; 2031 info->tcpi_rcv_ssthresh = tp->rcv_ssthresh; 2032 info->tcpi_rtt = jiffies_to_usecs(tp->srtt)>>3; 2033 info->tcpi_rttvar = jiffies_to_usecs(tp->mdev)>>2; 2034 info->tcpi_snd_ssthresh = tp->snd_ssthresh; 2035 info->tcpi_snd_cwnd = tp->snd_cwnd; 2036 info->tcpi_advmss = tp->advmss; 2037 info->tcpi_reordering = tp->reordering; 2038 2039 info->tcpi_rcv_rtt = jiffies_to_usecs(tp->rcv_rtt_est.rtt)>>3; 2040 info->tcpi_rcv_space = tp->rcvq_space.space; 2041 2042 info->tcpi_total_retrans = tp->total_retrans; 2043 } 2044 2045 EXPORT_SYMBOL_GPL(tcp_get_info); 2046 2047 static int do_tcp_getsockopt(struct sock *sk, int level, 2048 int optname, char __user *optval, int __user *optlen) 2049 { 2050 struct inet_connection_sock *icsk = inet_csk(sk); 2051 struct tcp_sock *tp = tcp_sk(sk); 2052 int val, len; 2053 2054 if (get_user(len, optlen)) 2055 return -EFAULT; 2056 2057 len = min_t(unsigned int, len, sizeof(int)); 2058 2059 if (len < 0) 2060 return -EINVAL; 2061 2062 switch (optname) { 2063 case TCP_MAXSEG: 2064 val = tp->mss_cache; 2065 if (!val && ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN))) 2066 val = tp->rx_opt.user_mss; 2067 break; 2068 case TCP_NODELAY: 2069 val = !!(tp->nonagle&TCP_NAGLE_OFF); 2070 break; 2071 case TCP_CORK: 2072 val = !!(tp->nonagle&TCP_NAGLE_CORK); 2073 break; 2074 case TCP_KEEPIDLE: 2075 val = (tp->keepalive_time ? : sysctl_tcp_keepalive_time) / HZ; 2076 break; 2077 case TCP_KEEPINTVL: 2078 val = (tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl) / HZ; 2079 break; 2080 case TCP_KEEPCNT: 2081 val = tp->keepalive_probes ? : sysctl_tcp_keepalive_probes; 2082 break; 2083 case TCP_SYNCNT: 2084 val = icsk->icsk_syn_retries ? : sysctl_tcp_syn_retries; 2085 break; 2086 case TCP_LINGER2: 2087 val = tp->linger2; 2088 if (val >= 0) 2089 val = (val ? : sysctl_tcp_fin_timeout) / HZ; 2090 break; 2091 case TCP_DEFER_ACCEPT: 2092 val = !icsk->icsk_accept_queue.rskq_defer_accept ? 0 : 2093 ((TCP_TIMEOUT_INIT / HZ) << (icsk->icsk_accept_queue.rskq_defer_accept - 1)); 2094 break; 2095 case TCP_WINDOW_CLAMP: 2096 val = tp->window_clamp; 2097 break; 2098 case TCP_INFO: { 2099 struct tcp_info info; 2100 2101 if (get_user(len, optlen)) 2102 return -EFAULT; 2103 2104 tcp_get_info(sk, &info); 2105 2106 len = min_t(unsigned int, len, sizeof(info)); 2107 if (put_user(len, optlen)) 2108 return -EFAULT; 2109 if (copy_to_user(optval, &info, len)) 2110 return -EFAULT; 2111 return 0; 2112 } 2113 case TCP_QUICKACK: 2114 val = !icsk->icsk_ack.pingpong; 2115 break; 2116 2117 case TCP_CONGESTION: 2118 if (get_user(len, optlen)) 2119 return -EFAULT; 2120 len = min_t(unsigned int, len, TCP_CA_NAME_MAX); 2121 if (put_user(len, optlen)) 2122 return -EFAULT; 2123 if (copy_to_user(optval, icsk->icsk_ca_ops->name, len)) 2124 return -EFAULT; 2125 return 0; 2126 default: 2127 return -ENOPROTOOPT; 2128 } 2129 2130 if (put_user(len, optlen)) 2131 return -EFAULT; 2132 if (copy_to_user(optval, &val, len)) 2133 return -EFAULT; 2134 return 0; 2135 } 2136 2137 int tcp_getsockopt(struct sock *sk, int level, int optname, char __user *optval, 2138 int __user *optlen) 2139 { 2140 struct inet_connection_sock *icsk = inet_csk(sk); 2141 2142 if (level != SOL_TCP) 2143 return icsk->icsk_af_ops->getsockopt(sk, level, optname, 2144 optval, optlen); 2145 return do_tcp_getsockopt(sk, level, optname, optval, optlen); 2146 } 2147 2148 #ifdef CONFIG_COMPAT 2149 int compat_tcp_getsockopt(struct sock *sk, int level, int optname, 2150 char __user *optval, int __user *optlen) 2151 { 2152 if (level != SOL_TCP) 2153 return inet_csk_compat_getsockopt(sk, level, optname, 2154 optval, optlen); 2155 return do_tcp_getsockopt(sk, level, optname, optval, optlen); 2156 } 2157 2158 EXPORT_SYMBOL(compat_tcp_getsockopt); 2159 #endif 2160 2161 struct sk_buff *tcp_tso_segment(struct sk_buff *skb, int features) 2162 { 2163 struct sk_buff *segs = ERR_PTR(-EINVAL); 2164 struct tcphdr *th; 2165 unsigned thlen; 2166 unsigned int seq; 2167 __be32 delta; 2168 unsigned int oldlen; 2169 unsigned int len; 2170 2171 if (!pskb_may_pull(skb, sizeof(*th))) 2172 goto out; 2173 2174 th = tcp_hdr(skb); 2175 thlen = th->doff * 4; 2176 if (thlen < sizeof(*th)) 2177 goto out; 2178 2179 if (!pskb_may_pull(skb, thlen)) 2180 goto out; 2181 2182 oldlen = (u16)~skb->len; 2183 __skb_pull(skb, thlen); 2184 2185 if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) { 2186 /* Packet is from an untrusted source, reset gso_segs. */ 2187 int type = skb_shinfo(skb)->gso_type; 2188 int mss; 2189 2190 if (unlikely(type & 2191 ~(SKB_GSO_TCPV4 | 2192 SKB_GSO_DODGY | 2193 SKB_GSO_TCP_ECN | 2194 SKB_GSO_TCPV6 | 2195 0) || 2196 !(type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6)))) 2197 goto out; 2198 2199 mss = skb_shinfo(skb)->gso_size; 2200 skb_shinfo(skb)->gso_segs = (skb->len + mss - 1) / mss; 2201 2202 segs = NULL; 2203 goto out; 2204 } 2205 2206 segs = skb_segment(skb, features); 2207 if (IS_ERR(segs)) 2208 goto out; 2209 2210 len = skb_shinfo(skb)->gso_size; 2211 delta = htonl(oldlen + (thlen + len)); 2212 2213 skb = segs; 2214 th = tcp_hdr(skb); 2215 seq = ntohl(th->seq); 2216 2217 do { 2218 th->fin = th->psh = 0; 2219 2220 th->check = ~csum_fold((__force __wsum)((__force u32)th->check + 2221 (__force u32)delta)); 2222 if (skb->ip_summed != CHECKSUM_PARTIAL) 2223 th->check = 2224 csum_fold(csum_partial(skb_transport_header(skb), 2225 thlen, skb->csum)); 2226 2227 seq += len; 2228 skb = skb->next; 2229 th = tcp_hdr(skb); 2230 2231 th->seq = htonl(seq); 2232 th->cwr = 0; 2233 } while (skb->next); 2234 2235 delta = htonl(oldlen + (skb->tail - skb->transport_header) + 2236 skb->data_len); 2237 th->check = ~csum_fold((__force __wsum)((__force u32)th->check + 2238 (__force u32)delta)); 2239 if (skb->ip_summed != CHECKSUM_PARTIAL) 2240 th->check = csum_fold(csum_partial(skb_transport_header(skb), 2241 thlen, skb->csum)); 2242 2243 out: 2244 return segs; 2245 } 2246 EXPORT_SYMBOL(tcp_tso_segment); 2247 2248 #ifdef CONFIG_TCP_MD5SIG 2249 static unsigned long tcp_md5sig_users; 2250 static struct tcp_md5sig_pool **tcp_md5sig_pool; 2251 static DEFINE_SPINLOCK(tcp_md5sig_pool_lock); 2252 2253 static void __tcp_free_md5sig_pool(struct tcp_md5sig_pool **pool) 2254 { 2255 int cpu; 2256 for_each_possible_cpu(cpu) { 2257 struct tcp_md5sig_pool *p = *per_cpu_ptr(pool, cpu); 2258 if (p) { 2259 if (p->md5_desc.tfm) 2260 crypto_free_hash(p->md5_desc.tfm); 2261 kfree(p); 2262 p = NULL; 2263 } 2264 } 2265 free_percpu(pool); 2266 } 2267 2268 void tcp_free_md5sig_pool(void) 2269 { 2270 struct tcp_md5sig_pool **pool = NULL; 2271 2272 spin_lock_bh(&tcp_md5sig_pool_lock); 2273 if (--tcp_md5sig_users == 0) { 2274 pool = tcp_md5sig_pool; 2275 tcp_md5sig_pool = NULL; 2276 } 2277 spin_unlock_bh(&tcp_md5sig_pool_lock); 2278 if (pool) 2279 __tcp_free_md5sig_pool(pool); 2280 } 2281 2282 EXPORT_SYMBOL(tcp_free_md5sig_pool); 2283 2284 static struct tcp_md5sig_pool **__tcp_alloc_md5sig_pool(void) 2285 { 2286 int cpu; 2287 struct tcp_md5sig_pool **pool; 2288 2289 pool = alloc_percpu(struct tcp_md5sig_pool *); 2290 if (!pool) 2291 return NULL; 2292 2293 for_each_possible_cpu(cpu) { 2294 struct tcp_md5sig_pool *p; 2295 struct crypto_hash *hash; 2296 2297 p = kzalloc(sizeof(*p), GFP_KERNEL); 2298 if (!p) 2299 goto out_free; 2300 *per_cpu_ptr(pool, cpu) = p; 2301 2302 hash = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC); 2303 if (!hash || IS_ERR(hash)) 2304 goto out_free; 2305 2306 p->md5_desc.tfm = hash; 2307 } 2308 return pool; 2309 out_free: 2310 __tcp_free_md5sig_pool(pool); 2311 return NULL; 2312 } 2313 2314 struct tcp_md5sig_pool **tcp_alloc_md5sig_pool(void) 2315 { 2316 struct tcp_md5sig_pool **pool; 2317 int alloc = 0; 2318 2319 retry: 2320 spin_lock_bh(&tcp_md5sig_pool_lock); 2321 pool = tcp_md5sig_pool; 2322 if (tcp_md5sig_users++ == 0) { 2323 alloc = 1; 2324 spin_unlock_bh(&tcp_md5sig_pool_lock); 2325 } else if (!pool) { 2326 tcp_md5sig_users--; 2327 spin_unlock_bh(&tcp_md5sig_pool_lock); 2328 cpu_relax(); 2329 goto retry; 2330 } else 2331 spin_unlock_bh(&tcp_md5sig_pool_lock); 2332 2333 if (alloc) { 2334 /* we cannot hold spinlock here because this may sleep. */ 2335 struct tcp_md5sig_pool **p = __tcp_alloc_md5sig_pool(); 2336 spin_lock_bh(&tcp_md5sig_pool_lock); 2337 if (!p) { 2338 tcp_md5sig_users--; 2339 spin_unlock_bh(&tcp_md5sig_pool_lock); 2340 return NULL; 2341 } 2342 pool = tcp_md5sig_pool; 2343 if (pool) { 2344 /* oops, it has already been assigned. */ 2345 spin_unlock_bh(&tcp_md5sig_pool_lock); 2346 __tcp_free_md5sig_pool(p); 2347 } else { 2348 tcp_md5sig_pool = pool = p; 2349 spin_unlock_bh(&tcp_md5sig_pool_lock); 2350 } 2351 } 2352 return pool; 2353 } 2354 2355 EXPORT_SYMBOL(tcp_alloc_md5sig_pool); 2356 2357 struct tcp_md5sig_pool *__tcp_get_md5sig_pool(int cpu) 2358 { 2359 struct tcp_md5sig_pool **p; 2360 spin_lock_bh(&tcp_md5sig_pool_lock); 2361 p = tcp_md5sig_pool; 2362 if (p) 2363 tcp_md5sig_users++; 2364 spin_unlock_bh(&tcp_md5sig_pool_lock); 2365 return (p ? *per_cpu_ptr(p, cpu) : NULL); 2366 } 2367 2368 EXPORT_SYMBOL(__tcp_get_md5sig_pool); 2369 2370 void __tcp_put_md5sig_pool(void) 2371 { 2372 tcp_free_md5sig_pool(); 2373 } 2374 2375 EXPORT_SYMBOL(__tcp_put_md5sig_pool); 2376 #endif 2377 2378 void tcp_done(struct sock *sk) 2379 { 2380 if(sk->sk_state == TCP_SYN_SENT || sk->sk_state == TCP_SYN_RECV) 2381 TCP_INC_STATS_BH(TCP_MIB_ATTEMPTFAILS); 2382 2383 tcp_set_state(sk, TCP_CLOSE); 2384 tcp_clear_xmit_timers(sk); 2385 2386 sk->sk_shutdown = SHUTDOWN_MASK; 2387 2388 if (!sock_flag(sk, SOCK_DEAD)) 2389 sk->sk_state_change(sk); 2390 else 2391 inet_csk_destroy_sock(sk); 2392 } 2393 EXPORT_SYMBOL_GPL(tcp_done); 2394 2395 extern void __skb_cb_too_small_for_tcp(int, int); 2396 extern struct tcp_congestion_ops tcp_reno; 2397 2398 static __initdata unsigned long thash_entries; 2399 static int __init set_thash_entries(char *str) 2400 { 2401 if (!str) 2402 return 0; 2403 thash_entries = simple_strtoul(str, &str, 0); 2404 return 1; 2405 } 2406 __setup("thash_entries=", set_thash_entries); 2407 2408 void __init tcp_init(void) 2409 { 2410 struct sk_buff *skb = NULL; 2411 unsigned long limit; 2412 int order, i, max_share; 2413 2414 if (sizeof(struct tcp_skb_cb) > sizeof(skb->cb)) 2415 __skb_cb_too_small_for_tcp(sizeof(struct tcp_skb_cb), 2416 sizeof(skb->cb)); 2417 2418 tcp_hashinfo.bind_bucket_cachep = 2419 kmem_cache_create("tcp_bind_bucket", 2420 sizeof(struct inet_bind_bucket), 0, 2421 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); 2422 2423 /* Size and allocate the main established and bind bucket 2424 * hash tables. 2425 * 2426 * The methodology is similar to that of the buffer cache. 2427 */ 2428 tcp_hashinfo.ehash = 2429 alloc_large_system_hash("TCP established", 2430 sizeof(struct inet_ehash_bucket), 2431 thash_entries, 2432 (num_physpages >= 128 * 1024) ? 2433 13 : 15, 2434 0, 2435 &tcp_hashinfo.ehash_size, 2436 NULL, 2437 0); 2438 tcp_hashinfo.ehash_size = 1 << tcp_hashinfo.ehash_size; 2439 for (i = 0; i < tcp_hashinfo.ehash_size; i++) { 2440 rwlock_init(&tcp_hashinfo.ehash[i].lock); 2441 INIT_HLIST_HEAD(&tcp_hashinfo.ehash[i].chain); 2442 INIT_HLIST_HEAD(&tcp_hashinfo.ehash[i].twchain); 2443 } 2444 2445 tcp_hashinfo.bhash = 2446 alloc_large_system_hash("TCP bind", 2447 sizeof(struct inet_bind_hashbucket), 2448 tcp_hashinfo.ehash_size, 2449 (num_physpages >= 128 * 1024) ? 2450 13 : 15, 2451 0, 2452 &tcp_hashinfo.bhash_size, 2453 NULL, 2454 64 * 1024); 2455 tcp_hashinfo.bhash_size = 1 << tcp_hashinfo.bhash_size; 2456 for (i = 0; i < tcp_hashinfo.bhash_size; i++) { 2457 spin_lock_init(&tcp_hashinfo.bhash[i].lock); 2458 INIT_HLIST_HEAD(&tcp_hashinfo.bhash[i].chain); 2459 } 2460 2461 /* Try to be a bit smarter and adjust defaults depending 2462 * on available memory. 2463 */ 2464 for (order = 0; ((1 << order) << PAGE_SHIFT) < 2465 (tcp_hashinfo.bhash_size * sizeof(struct inet_bind_hashbucket)); 2466 order++) 2467 ; 2468 if (order >= 4) { 2469 sysctl_local_port_range[0] = 32768; 2470 sysctl_local_port_range[1] = 61000; 2471 tcp_death_row.sysctl_max_tw_buckets = 180000; 2472 sysctl_tcp_max_orphans = 4096 << (order - 4); 2473 sysctl_max_syn_backlog = 1024; 2474 } else if (order < 3) { 2475 sysctl_local_port_range[0] = 1024 * (3 - order); 2476 tcp_death_row.sysctl_max_tw_buckets >>= (3 - order); 2477 sysctl_tcp_max_orphans >>= (3 - order); 2478 sysctl_max_syn_backlog = 128; 2479 } 2480 2481 /* Set the pressure threshold to be a fraction of global memory that 2482 * is up to 1/2 at 256 MB, decreasing toward zero with the amount of 2483 * memory, with a floor of 128 pages. 2484 */ 2485 limit = min(nr_all_pages, 1UL<<(28-PAGE_SHIFT)) >> (20-PAGE_SHIFT); 2486 limit = (limit * (nr_all_pages >> (20-PAGE_SHIFT))) >> (PAGE_SHIFT-11); 2487 limit = max(limit, 128UL); 2488 sysctl_tcp_mem[0] = limit / 4 * 3; 2489 sysctl_tcp_mem[1] = limit; 2490 sysctl_tcp_mem[2] = sysctl_tcp_mem[0] * 2; 2491 2492 /* Set per-socket limits to no more than 1/128 the pressure threshold */ 2493 limit = ((unsigned long)sysctl_tcp_mem[1]) << (PAGE_SHIFT - 7); 2494 max_share = min(4UL*1024*1024, limit); 2495 2496 sysctl_tcp_wmem[0] = SK_STREAM_MEM_QUANTUM; 2497 sysctl_tcp_wmem[1] = 16*1024; 2498 sysctl_tcp_wmem[2] = max(64*1024, max_share); 2499 2500 sysctl_tcp_rmem[0] = SK_STREAM_MEM_QUANTUM; 2501 sysctl_tcp_rmem[1] = 87380; 2502 sysctl_tcp_rmem[2] = max(87380, max_share); 2503 2504 printk(KERN_INFO "TCP: Hash tables configured " 2505 "(established %d bind %d)\n", 2506 tcp_hashinfo.ehash_size, tcp_hashinfo.bhash_size); 2507 2508 tcp_register_congestion_control(&tcp_reno); 2509 } 2510 2511 EXPORT_SYMBOL(tcp_close); 2512 EXPORT_SYMBOL(tcp_disconnect); 2513 EXPORT_SYMBOL(tcp_getsockopt); 2514 EXPORT_SYMBOL(tcp_ioctl); 2515 EXPORT_SYMBOL(tcp_poll); 2516 EXPORT_SYMBOL(tcp_read_sock); 2517 EXPORT_SYMBOL(tcp_recvmsg); 2518 EXPORT_SYMBOL(tcp_sendmsg); 2519 EXPORT_SYMBOL(tcp_sendpage); 2520 EXPORT_SYMBOL(tcp_setsockopt); 2521 EXPORT_SYMBOL(tcp_shutdown); 2522 EXPORT_SYMBOL(tcp_statistics); 2523