1 /* $NetBSD: serverloop.c,v 1.5 2012/12/12 17:42:40 christos Exp $ */ 2 /* $OpenBSD: serverloop.c,v 1.162 2012/06/20 04:42:58 djm Exp $ */ 3 /* 4 * Author: Tatu Ylonen <ylo@cs.hut.fi> 5 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 6 * All rights reserved 7 * Server main loop for handling the interactive session. 8 * 9 * As far as I am concerned, the code I have written for this software 10 * can be used freely for any purpose. Any derived versions of this 11 * software must be clearly marked as such, and if the derived work is 12 * incompatible with the protocol description in the RFC file, it must be 13 * called by a name other than "ssh" or "Secure Shell". 14 * 15 * SSH2 support by Markus Friedl. 16 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 17 * 18 * Redistribution and use in source and binary forms, with or without 19 * modification, are permitted provided that the following conditions 20 * are met: 21 * 1. Redistributions of source code must retain the above copyright 22 * notice, this list of conditions and the following disclaimer. 23 * 2. Redistributions in binary form must reproduce the above copyright 24 * notice, this list of conditions and the following disclaimer in the 25 * documentation and/or other materials provided with the distribution. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 28 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 29 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 30 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 31 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 32 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 33 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 34 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 35 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 36 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 37 */ 38 39 #include "includes.h" 40 __RCSID("$NetBSD: serverloop.c,v 1.5 2012/12/12 17:42:40 christos Exp $"); 41 #include <sys/types.h> 42 #include <sys/wait.h> 43 #include <sys/socket.h> 44 #include <sys/time.h> 45 #include <sys/param.h> 46 #include <sys/queue.h> 47 48 #include <netinet/in.h> 49 50 #include <errno.h> 51 #include <fcntl.h> 52 #include <pwd.h> 53 #include <signal.h> 54 #include <string.h> 55 #include <termios.h> 56 #include <unistd.h> 57 #include <stdarg.h> 58 59 #include "xmalloc.h" 60 #include "packet.h" 61 #include "buffer.h" 62 #include "log.h" 63 #include "servconf.h" 64 #include "canohost.h" 65 #include "sshpty.h" 66 #include "channels.h" 67 #include "compat.h" 68 #include "ssh1.h" 69 #include "ssh2.h" 70 #include "key.h" 71 #include "cipher.h" 72 #include "kex.h" 73 #include "hostfile.h" 74 #include "auth.h" 75 #include "session.h" 76 #include "dispatch.h" 77 #include "auth-options.h" 78 #include "serverloop.h" 79 #include "misc.h" 80 #include "roaming.h" 81 82 extern ServerOptions options; 83 84 /* XXX */ 85 extern Kex *xxx_kex; 86 extern Authctxt *the_authctxt; 87 extern int use_privsep; 88 89 static Buffer stdin_buffer; /* Buffer for stdin data. */ 90 static Buffer stdout_buffer; /* Buffer for stdout data. */ 91 static Buffer stderr_buffer; /* Buffer for stderr data. */ 92 static int fdin; /* Descriptor for stdin (for writing) */ 93 static int fdout; /* Descriptor for stdout (for reading); 94 May be same number as fdin. */ 95 static int fderr; /* Descriptor for stderr. May be -1. */ 96 static u_long stdin_bytes = 0; /* Number of bytes written to stdin. */ 97 static u_long stdout_bytes = 0; /* Number of stdout bytes sent to client. */ 98 static u_long stderr_bytes = 0; /* Number of stderr bytes sent to client. */ 99 static u_long fdout_bytes = 0; /* Number of stdout bytes read from program. */ 100 static int stdin_eof = 0; /* EOF message received from client. */ 101 static int fdout_eof = 0; /* EOF encountered reading from fdout. */ 102 static int fderr_eof = 0; /* EOF encountered readung from fderr. */ 103 static int fdin_is_tty = 0; /* fdin points to a tty. */ 104 static int connection_in; /* Connection to client (input). */ 105 static int connection_out; /* Connection to client (output). */ 106 static int connection_closed = 0; /* Connection to client closed. */ 107 static u_int buffer_high; /* "Soft" max buffer size. */ 108 static int no_more_sessions = 0; /* Disallow further sessions. */ 109 110 /* 111 * This SIGCHLD kludge is used to detect when the child exits. The server 112 * will exit after that, as soon as forwarded connections have terminated. 113 */ 114 115 static volatile sig_atomic_t child_terminated = 0; /* The child has terminated. */ 116 117 /* Cleanup on signals (!use_privsep case only) */ 118 static volatile sig_atomic_t received_sigterm = 0; 119 120 /* prototypes */ 121 static void server_init_dispatch(void); 122 123 /* 124 * Returns current time in seconds from Jan 1, 1970 with the maximum 125 * available resolution. 126 */ 127 128 static double 129 get_current_time(void) 130 { 131 struct timeval tv; 132 gettimeofday(&tv, NULL); 133 return (double) tv.tv_sec + (double) tv.tv_usec / 1000000.0; 134 } 135 136 /* 137 * we write to this pipe if a SIGCHLD is caught in order to avoid 138 * the race between select() and child_terminated 139 */ 140 static int notify_pipe[2]; 141 static void 142 notify_setup(void) 143 { 144 if (pipe(notify_pipe) < 0) { 145 error("pipe(notify_pipe) failed %s", strerror(errno)); 146 } else if ((fcntl(notify_pipe[0], F_SETFD, FD_CLOEXEC) == -1) || 147 (fcntl(notify_pipe[1], F_SETFD, FD_CLOEXEC) == -1)) { 148 error("fcntl(notify_pipe, F_SETFD) failed %s", strerror(errno)); 149 close(notify_pipe[0]); 150 close(notify_pipe[1]); 151 } else { 152 set_nonblock(notify_pipe[0]); 153 set_nonblock(notify_pipe[1]); 154 return; 155 } 156 notify_pipe[0] = -1; /* read end */ 157 notify_pipe[1] = -1; /* write end */ 158 } 159 static void 160 notify_parent(void) 161 { 162 if (notify_pipe[1] != -1) 163 write(notify_pipe[1], "", 1); 164 } 165 static void 166 notify_prepare(fd_set *readset) 167 { 168 if (notify_pipe[0] != -1) 169 FD_SET(notify_pipe[0], readset); 170 } 171 static void 172 notify_done(fd_set *readset) 173 { 174 char c; 175 176 if (notify_pipe[0] != -1 && FD_ISSET(notify_pipe[0], readset)) 177 while (read(notify_pipe[0], &c, 1) != -1) 178 debug2("notify_done: reading"); 179 } 180 181 /*ARGSUSED*/ 182 static void 183 sigchld_handler(int sig) 184 { 185 int save_errno = errno; 186 child_terminated = 1; 187 signal(SIGCHLD, sigchld_handler); 188 notify_parent(); 189 errno = save_errno; 190 } 191 192 /*ARGSUSED*/ 193 static void 194 sigterm_handler(int sig) 195 { 196 received_sigterm = sig; 197 } 198 199 /* 200 * Make packets from buffered stderr data, and buffer it for sending 201 * to the client. 202 */ 203 static void 204 make_packets_from_stderr_data(void) 205 { 206 u_int len; 207 208 /* Send buffered stderr data to the client. */ 209 while (buffer_len(&stderr_buffer) > 0 && 210 packet_not_very_much_data_to_write()) { 211 len = buffer_len(&stderr_buffer); 212 if (packet_is_interactive()) { 213 if (len > 512) 214 len = 512; 215 } else { 216 /* Keep the packets at reasonable size. */ 217 if (len > packet_get_maxsize()) 218 len = packet_get_maxsize(); 219 } 220 packet_start(SSH_SMSG_STDERR_DATA); 221 packet_put_string(buffer_ptr(&stderr_buffer), len); 222 packet_send(); 223 buffer_consume(&stderr_buffer, len); 224 stderr_bytes += len; 225 } 226 } 227 228 /* 229 * Make packets from buffered stdout data, and buffer it for sending to the 230 * client. 231 */ 232 static void 233 make_packets_from_stdout_data(void) 234 { 235 u_int len; 236 237 /* Send buffered stdout data to the client. */ 238 while (buffer_len(&stdout_buffer) > 0 && 239 packet_not_very_much_data_to_write()) { 240 len = buffer_len(&stdout_buffer); 241 if (packet_is_interactive()) { 242 if (len > 512) 243 len = 512; 244 } else { 245 /* Keep the packets at reasonable size. */ 246 if (len > packet_get_maxsize()) 247 len = packet_get_maxsize(); 248 } 249 packet_start(SSH_SMSG_STDOUT_DATA); 250 packet_put_string(buffer_ptr(&stdout_buffer), len); 251 packet_send(); 252 buffer_consume(&stdout_buffer, len); 253 stdout_bytes += len; 254 } 255 } 256 257 static void 258 client_alive_check(void) 259 { 260 int channel_id; 261 262 /* timeout, check to see how many we have had */ 263 if (packet_inc_alive_timeouts() > options.client_alive_count_max) { 264 logit("Timeout, client not responding."); 265 cleanup_exit(255); 266 } 267 268 /* 269 * send a bogus global/channel request with "wantreply", 270 * we should get back a failure 271 */ 272 if ((channel_id = channel_find_open()) == -1) { 273 packet_start(SSH2_MSG_GLOBAL_REQUEST); 274 packet_put_cstring("keepalive@openssh.com"); 275 packet_put_char(1); /* boolean: want reply */ 276 } else { 277 channel_request_start(channel_id, "keepalive@openssh.com", 1); 278 } 279 packet_send(); 280 } 281 282 /* 283 * Sleep in select() until we can do something. This will initialize the 284 * select masks. Upon return, the masks will indicate which descriptors 285 * have data or can accept data. Optionally, a maximum time can be specified 286 * for the duration of the wait (0 = infinite). 287 */ 288 static void 289 wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp, 290 u_int *nallocp, u_int max_time_milliseconds) 291 { 292 struct timeval tv, *tvp; 293 int ret; 294 time_t minwait_secs = 0; 295 int client_alive_scheduled = 0; 296 297 /* Allocate and update select() masks for channel descriptors. */ 298 channel_prepare_select(readsetp, writesetp, maxfdp, nallocp, 299 &minwait_secs, 0); 300 301 if (minwait_secs != 0) 302 max_time_milliseconds = MIN(max_time_milliseconds, 303 (u_int)minwait_secs * 1000); 304 305 /* 306 * if using client_alive, set the max timeout accordingly, 307 * and indicate that this particular timeout was for client 308 * alive by setting the client_alive_scheduled flag. 309 * 310 * this could be randomized somewhat to make traffic 311 * analysis more difficult, but we're not doing it yet. 312 */ 313 if (compat20 && 314 max_time_milliseconds == 0 && options.client_alive_interval) { 315 client_alive_scheduled = 1; 316 max_time_milliseconds = options.client_alive_interval * 1000; 317 } 318 319 if (compat20) { 320 #if 0 321 /* wrong: bad condition XXX */ 322 if (channel_not_very_much_buffered_data()) 323 #endif 324 FD_SET(connection_in, *readsetp); 325 } else { 326 /* 327 * Read packets from the client unless we have too much 328 * buffered stdin or channel data. 329 */ 330 if (buffer_len(&stdin_buffer) < buffer_high && 331 channel_not_very_much_buffered_data()) 332 FD_SET(connection_in, *readsetp); 333 /* 334 * If there is not too much data already buffered going to 335 * the client, try to get some more data from the program. 336 */ 337 if (packet_not_very_much_data_to_write()) { 338 if (!fdout_eof) 339 FD_SET(fdout, *readsetp); 340 if (!fderr_eof) 341 FD_SET(fderr, *readsetp); 342 } 343 /* 344 * If we have buffered data, try to write some of that data 345 * to the program. 346 */ 347 if (fdin != -1 && buffer_len(&stdin_buffer) > 0) 348 FD_SET(fdin, *writesetp); 349 } 350 notify_prepare(*readsetp); 351 352 /* 353 * If we have buffered packet data going to the client, mark that 354 * descriptor. 355 */ 356 if (packet_have_data_to_write()) 357 FD_SET(connection_out, *writesetp); 358 359 /* 360 * If child has terminated and there is enough buffer space to read 361 * from it, then read as much as is available and exit. 362 */ 363 if (child_terminated && packet_not_very_much_data_to_write()) 364 if (max_time_milliseconds == 0 || client_alive_scheduled) 365 max_time_milliseconds = 100; 366 367 if (max_time_milliseconds == 0) 368 tvp = NULL; 369 else { 370 tv.tv_sec = max_time_milliseconds / 1000; 371 tv.tv_usec = 1000 * (max_time_milliseconds % 1000); 372 tvp = &tv; 373 } 374 375 /* Wait for something to happen, or the timeout to expire. */ 376 ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp); 377 378 if (ret == -1) { 379 memset(*readsetp, 0, *nallocp); 380 memset(*writesetp, 0, *nallocp); 381 if (errno != EINTR) 382 error("select: %.100s", strerror(errno)); 383 } else if (ret == 0 && client_alive_scheduled) 384 client_alive_check(); 385 386 notify_done(*readsetp); 387 } 388 389 /* 390 * Processes input from the client and the program. Input data is stored 391 * in buffers and processed later. 392 */ 393 static void 394 process_input(fd_set *readset) 395 { 396 int len; 397 char buf[16384]; 398 399 /* Read and buffer any input data from the client. */ 400 if (FD_ISSET(connection_in, readset)) { 401 int cont = 0; 402 len = roaming_read(connection_in, buf, sizeof(buf), &cont); 403 if (len == 0) { 404 if (cont) 405 return; 406 verbose("Connection closed by %.100s", 407 get_remote_ipaddr()); 408 connection_closed = 1; 409 if (compat20) 410 return; 411 cleanup_exit(255); 412 } else if (len < 0) { 413 if (errno != EINTR && errno != EAGAIN) { 414 verbose("Read error from remote host " 415 "%.100s: %.100s", 416 get_remote_ipaddr(), strerror(errno)); 417 cleanup_exit(255); 418 } 419 } else { 420 /* Buffer any received data. */ 421 packet_process_incoming(buf, len); 422 fdout_bytes += len; 423 } 424 } 425 if (compat20) 426 return; 427 428 /* Read and buffer any available stdout data from the program. */ 429 if (!fdout_eof && FD_ISSET(fdout, readset)) { 430 len = read(fdout, buf, sizeof(buf)); 431 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 432 /* do nothing */ 433 } else if (len <= 0) { 434 fdout_eof = 1; 435 } else { 436 buffer_append(&stdout_buffer, buf, len); 437 debug ("FD out now: %ld", fdout_bytes); 438 fdout_bytes += len; 439 } 440 } 441 /* Read and buffer any available stderr data from the program. */ 442 if (!fderr_eof && FD_ISSET(fderr, readset)) { 443 len = read(fderr, buf, sizeof(buf)); 444 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 445 /* do nothing */ 446 } else if (len <= 0) { 447 fderr_eof = 1; 448 } else { 449 buffer_append(&stderr_buffer, buf, len); 450 } 451 } 452 } 453 454 /* 455 * Sends data from internal buffers to client program stdin. 456 */ 457 static void 458 process_output(fd_set *writeset) 459 { 460 struct termios tio; 461 u_char *data; 462 u_int dlen; 463 int len; 464 465 /* Write buffered data to program stdin. */ 466 if (!compat20 && fdin != -1 && FD_ISSET(fdin, writeset)) { 467 data = buffer_ptr(&stdin_buffer); 468 dlen = buffer_len(&stdin_buffer); 469 len = write(fdin, data, dlen); 470 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 471 /* do nothing */ 472 } else if (len <= 0) { 473 if (fdin != fdout) 474 close(fdin); 475 else 476 shutdown(fdin, SHUT_WR); /* We will no longer send. */ 477 fdin = -1; 478 } else { 479 /* Successful write. */ 480 if (fdin_is_tty && dlen >= 1 && data[0] != '\r' && 481 tcgetattr(fdin, &tio) == 0 && 482 !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) { 483 /* 484 * Simulate echo to reduce the impact of 485 * traffic analysis 486 */ 487 packet_send_ignore(len); 488 packet_send(); 489 } 490 /* Consume the data from the buffer. */ 491 buffer_consume(&stdin_buffer, len); 492 /* Update the count of bytes written to the program. */ 493 stdin_bytes += len; 494 } 495 } 496 /* Send any buffered packet data to the client. */ 497 if (FD_ISSET(connection_out, writeset)) 498 stdin_bytes += packet_write_poll(); 499 } 500 501 /* 502 * Wait until all buffered output has been sent to the client. 503 * This is used when the program terminates. 504 */ 505 static void 506 drain_output(void) 507 { 508 /* Send any buffered stdout data to the client. */ 509 if (buffer_len(&stdout_buffer) > 0) { 510 packet_start(SSH_SMSG_STDOUT_DATA); 511 packet_put_string(buffer_ptr(&stdout_buffer), 512 buffer_len(&stdout_buffer)); 513 packet_send(); 514 /* Update the count of sent bytes. */ 515 stdout_bytes += buffer_len(&stdout_buffer); 516 } 517 /* Send any buffered stderr data to the client. */ 518 if (buffer_len(&stderr_buffer) > 0) { 519 packet_start(SSH_SMSG_STDERR_DATA); 520 packet_put_string(buffer_ptr(&stderr_buffer), 521 buffer_len(&stderr_buffer)); 522 packet_send(); 523 /* Update the count of sent bytes. */ 524 stderr_bytes += buffer_len(&stderr_buffer); 525 } 526 /* Wait until all buffered data has been written to the client. */ 527 packet_write_wait(); 528 } 529 530 static void 531 process_buffered_input_packets(void) 532 { 533 dispatch_run(DISPATCH_NONBLOCK, NULL, compat20 ? xxx_kex : NULL); 534 } 535 536 /* 537 * Performs the interactive session. This handles data transmission between 538 * the client and the program. Note that the notion of stdin, stdout, and 539 * stderr in this function is sort of reversed: this function writes to 540 * stdin (of the child program), and reads from stdout and stderr (of the 541 * child program). 542 */ 543 void 544 server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg) 545 { 546 fd_set *readset = NULL, *writeset = NULL; 547 int max_fd = 0; 548 u_int nalloc = 0; 549 int wait_status; /* Status returned by wait(). */ 550 pid_t wait_pid; /* pid returned by wait(). */ 551 int waiting_termination = 0; /* Have displayed waiting close message. */ 552 u_int max_time_milliseconds; 553 u_int previous_stdout_buffer_bytes; 554 u_int stdout_buffer_bytes; 555 int type; 556 557 debug("Entering interactive session."); 558 559 /* Initialize the SIGCHLD kludge. */ 560 child_terminated = 0; 561 signal(SIGCHLD, sigchld_handler); 562 563 if (!use_privsep) { 564 signal(SIGTERM, sigterm_handler); 565 signal(SIGINT, sigterm_handler); 566 signal(SIGQUIT, sigterm_handler); 567 } 568 569 /* Initialize our global variables. */ 570 fdin = fdin_arg; 571 fdout = fdout_arg; 572 fderr = fderr_arg; 573 574 /* nonblocking IO */ 575 set_nonblock(fdin); 576 set_nonblock(fdout); 577 /* we don't have stderr for interactive terminal sessions, see below */ 578 if (fderr != -1) 579 set_nonblock(fderr); 580 581 if (!(datafellows & SSH_BUG_IGNOREMSG) && isatty(fdin)) 582 fdin_is_tty = 1; 583 584 connection_in = packet_get_connection_in(); 585 connection_out = packet_get_connection_out(); 586 587 notify_setup(); 588 589 previous_stdout_buffer_bytes = 0; 590 591 /* Set approximate I/O buffer size. */ 592 if (packet_is_interactive()) 593 buffer_high = 4096; 594 else 595 buffer_high = 64 * 1024; 596 597 #if 0 598 /* Initialize max_fd to the maximum of the known file descriptors. */ 599 max_fd = MAX(connection_in, connection_out); 600 max_fd = MAX(max_fd, fdin); 601 max_fd = MAX(max_fd, fdout); 602 if (fderr != -1) 603 max_fd = MAX(max_fd, fderr); 604 #endif 605 606 /* Initialize Initialize buffers. */ 607 buffer_init(&stdin_buffer); 608 buffer_init(&stdout_buffer); 609 buffer_init(&stderr_buffer); 610 611 /* 612 * If we have no separate fderr (which is the case when we have a pty 613 * - there we cannot make difference between data sent to stdout and 614 * stderr), indicate that we have seen an EOF from stderr. This way 615 * we don't need to check the descriptor everywhere. 616 */ 617 if (fderr == -1) 618 fderr_eof = 1; 619 620 server_init_dispatch(); 621 622 /* Main loop of the server for the interactive session mode. */ 623 for (;;) { 624 625 /* Process buffered packets from the client. */ 626 process_buffered_input_packets(); 627 628 /* 629 * If we have received eof, and there is no more pending 630 * input data, cause a real eof by closing fdin. 631 */ 632 if (stdin_eof && fdin != -1 && buffer_len(&stdin_buffer) == 0) { 633 if (fdin != fdout) 634 close(fdin); 635 else 636 shutdown(fdin, SHUT_WR); /* We will no longer send. */ 637 fdin = -1; 638 } 639 /* Make packets from buffered stderr data to send to the client. */ 640 make_packets_from_stderr_data(); 641 642 /* 643 * Make packets from buffered stdout data to send to the 644 * client. If there is very little to send, this arranges to 645 * not send them now, but to wait a short while to see if we 646 * are getting more data. This is necessary, as some systems 647 * wake up readers from a pty after each separate character. 648 */ 649 max_time_milliseconds = 0; 650 stdout_buffer_bytes = buffer_len(&stdout_buffer); 651 if (stdout_buffer_bytes != 0 && stdout_buffer_bytes < 256 && 652 stdout_buffer_bytes != previous_stdout_buffer_bytes) { 653 /* try again after a while */ 654 max_time_milliseconds = 10; 655 } else { 656 /* Send it now. */ 657 make_packets_from_stdout_data(); 658 } 659 previous_stdout_buffer_bytes = buffer_len(&stdout_buffer); 660 661 /* Send channel data to the client. */ 662 if (packet_not_very_much_data_to_write()) 663 channel_output_poll(); 664 665 /* 666 * Bail out of the loop if the program has closed its output 667 * descriptors, and we have no more data to send to the 668 * client, and there is no pending buffered data. 669 */ 670 if (fdout_eof && fderr_eof && !packet_have_data_to_write() && 671 buffer_len(&stdout_buffer) == 0 && buffer_len(&stderr_buffer) == 0) { 672 if (!channel_still_open()) 673 break; 674 if (!waiting_termination) { 675 const char *s = "Waiting for forwarded connections to terminate...\r\n"; 676 char *cp; 677 waiting_termination = 1; 678 buffer_append(&stderr_buffer, s, strlen(s)); 679 680 /* Display list of open channels. */ 681 cp = channel_open_message(); 682 buffer_append(&stderr_buffer, cp, strlen(cp)); 683 xfree(cp); 684 } 685 } 686 max_fd = MAX(connection_in, connection_out); 687 max_fd = MAX(max_fd, fdin); 688 max_fd = MAX(max_fd, fdout); 689 max_fd = MAX(max_fd, fderr); 690 max_fd = MAX(max_fd, notify_pipe[0]); 691 692 /* Sleep in select() until we can do something. */ 693 wait_until_can_do_something(&readset, &writeset, &max_fd, 694 &nalloc, max_time_milliseconds); 695 696 if (received_sigterm) { 697 logit("Exiting on signal %ld", (long)received_sigterm); 698 /* Clean up sessions, utmp, etc. */ 699 cleanup_exit(255); 700 } 701 702 /* Process any channel events. */ 703 channel_after_select(readset, writeset); 704 705 /* Process input from the client and from program stdout/stderr. */ 706 process_input(readset); 707 708 /* Process output to the client and to program stdin. */ 709 process_output(writeset); 710 } 711 if (readset) 712 xfree(readset); 713 if (writeset) 714 xfree(writeset); 715 716 /* Cleanup and termination code. */ 717 718 /* Wait until all output has been sent to the client. */ 719 drain_output(); 720 721 debug("End of interactive session; stdin %ld, stdout (read %ld, sent %ld), stderr %ld bytes.", 722 stdin_bytes, fdout_bytes, stdout_bytes, stderr_bytes); 723 724 /* Free and clear the buffers. */ 725 buffer_free(&stdin_buffer); 726 buffer_free(&stdout_buffer); 727 buffer_free(&stderr_buffer); 728 729 /* Close the file descriptors. */ 730 if (fdout != -1) 731 close(fdout); 732 fdout = -1; 733 fdout_eof = 1; 734 if (fderr != -1) 735 close(fderr); 736 fderr = -1; 737 fderr_eof = 1; 738 if (fdin != -1) 739 close(fdin); 740 fdin = -1; 741 742 channel_free_all(); 743 744 /* We no longer want our SIGCHLD handler to be called. */ 745 signal(SIGCHLD, SIG_DFL); 746 747 while ((wait_pid = waitpid(-1, &wait_status, 0)) < 0) 748 if (errno != EINTR) 749 packet_disconnect("wait: %.100s", strerror(errno)); 750 if (wait_pid != pid) 751 error("Strange, wait returned pid %ld, expected %ld", 752 (long)wait_pid, (long)pid); 753 754 /* Check if it exited normally. */ 755 if (WIFEXITED(wait_status)) { 756 /* Yes, normal exit. Get exit status and send it to the client. */ 757 debug("Command exited with status %d.", WEXITSTATUS(wait_status)); 758 packet_start(SSH_SMSG_EXITSTATUS); 759 packet_put_int(WEXITSTATUS(wait_status)); 760 packet_send(); 761 packet_write_wait(); 762 763 /* 764 * Wait for exit confirmation. Note that there might be 765 * other packets coming before it; however, the program has 766 * already died so we just ignore them. The client is 767 * supposed to respond with the confirmation when it receives 768 * the exit status. 769 */ 770 do { 771 type = packet_read(); 772 } 773 while (type != SSH_CMSG_EXIT_CONFIRMATION); 774 775 debug("Received exit confirmation."); 776 return; 777 } 778 /* Check if the program terminated due to a signal. */ 779 if (WIFSIGNALED(wait_status)) 780 packet_disconnect("Command terminated on signal %d.", 781 WTERMSIG(wait_status)); 782 783 /* Some weird exit cause. Just exit. */ 784 packet_disconnect("wait returned status %04x.", wait_status); 785 /* NOTREACHED */ 786 } 787 788 static void 789 collect_children(void) 790 { 791 pid_t pid; 792 sigset_t oset, nset; 793 int status; 794 795 /* block SIGCHLD while we check for dead children */ 796 sigemptyset(&nset); 797 sigaddset(&nset, SIGCHLD); 798 sigprocmask(SIG_BLOCK, &nset, &oset); 799 if (child_terminated) { 800 debug("Received SIGCHLD."); 801 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 802 (pid < 0 && errno == EINTR)) 803 if (pid > 0) 804 session_close_by_pid(pid, status); 805 child_terminated = 0; 806 } 807 sigprocmask(SIG_SETMASK, &oset, NULL); 808 } 809 810 void 811 server_loop2(Authctxt *authctxt) 812 { 813 fd_set *readset = NULL, *writeset = NULL; 814 int rekeying = 0, max_fd; 815 u_int nalloc = 0; 816 double start_time, total_time; 817 818 debug("Entering interactive session for SSH2."); 819 start_time = get_current_time(); 820 821 signal(SIGCHLD, sigchld_handler); 822 child_terminated = 0; 823 connection_in = packet_get_connection_in(); 824 connection_out = packet_get_connection_out(); 825 826 if (!use_privsep) { 827 signal(SIGTERM, sigterm_handler); 828 signal(SIGINT, sigterm_handler); 829 signal(SIGQUIT, sigterm_handler); 830 } 831 832 notify_setup(); 833 834 max_fd = MAX(connection_in, connection_out); 835 max_fd = MAX(max_fd, notify_pipe[0]); 836 837 server_init_dispatch(); 838 839 for (;;) { 840 process_buffered_input_packets(); 841 842 rekeying = (xxx_kex != NULL && !xxx_kex->done); 843 844 if (!rekeying && packet_not_very_much_data_to_write()) 845 channel_output_poll(); 846 wait_until_can_do_something(&readset, &writeset, &max_fd, 847 &nalloc, 0); 848 849 if (received_sigterm) { 850 logit("Exiting on signal %ld", (long)received_sigterm); 851 /* Clean up sessions, utmp, etc. */ 852 cleanup_exit(255); 853 } 854 855 collect_children(); 856 if (!rekeying) { 857 channel_after_select(readset, writeset); 858 if (packet_need_rekeying()) { 859 debug("need rekeying"); 860 xxx_kex->done = 0; 861 kex_send_kexinit(xxx_kex); 862 } 863 } 864 process_input(readset); 865 if (connection_closed) 866 break; 867 process_output(writeset); 868 } 869 collect_children(); 870 871 if (readset) 872 xfree(readset); 873 if (writeset) 874 xfree(writeset); 875 876 /* free all channels, no more reads and writes */ 877 channel_free_all(); 878 879 /* free remaining sessions, e.g. remove wtmp entries */ 880 session_destroy_all(NULL); 881 total_time = get_current_time() - start_time; 882 logit("SSH: Server;LType: Throughput;Remote: %s-%d;IN: %lu;OUT: %lu;Duration: %.1f;tPut_in: %.1f;tPut_out: %.1f", 883 get_remote_ipaddr(), get_remote_port(), 884 stdin_bytes, fdout_bytes, total_time, stdin_bytes / total_time, 885 fdout_bytes / total_time); 886 } 887 888 static void 889 server_input_keep_alive(int type, u_int32_t seq, void *ctxt) 890 { 891 debug("Got %d/%u for keepalive", type, seq); 892 /* 893 * reset timeout, since we got a sane answer from the client. 894 * even if this was generated by something other than 895 * the bogus CHANNEL_REQUEST we send for keepalives. 896 */ 897 packet_set_alive_timeouts(0); 898 } 899 900 static void 901 server_input_stdin_data(int type, u_int32_t seq, void *ctxt) 902 { 903 char *data; 904 u_int data_len; 905 906 /* Stdin data from the client. Append it to the buffer. */ 907 /* Ignore any data if the client has closed stdin. */ 908 if (fdin == -1) 909 return; 910 data = packet_get_string(&data_len); 911 packet_check_eom(); 912 buffer_append(&stdin_buffer, data, data_len); 913 memset(data, 0, data_len); 914 xfree(data); 915 } 916 917 static void 918 server_input_eof(int type, u_int32_t seq, void *ctxt) 919 { 920 /* 921 * Eof from the client. The stdin descriptor to the 922 * program will be closed when all buffered data has 923 * drained. 924 */ 925 debug("EOF received for stdin."); 926 packet_check_eom(); 927 stdin_eof = 1; 928 } 929 930 static void 931 server_input_window_size(int type, u_int32_t seq, void *ctxt) 932 { 933 u_int row = packet_get_int(); 934 u_int col = packet_get_int(); 935 u_int xpixel = packet_get_int(); 936 u_int ypixel = packet_get_int(); 937 938 debug("Window change received."); 939 packet_check_eom(); 940 if (fdin != -1) 941 pty_change_window_size(fdin, row, col, xpixel, ypixel); 942 } 943 944 static Channel * 945 server_request_direct_tcpip(void) 946 { 947 Channel *c; 948 char *target, *originator; 949 u_short target_port, originator_port; 950 951 target = packet_get_string(NULL); 952 target_port = packet_get_int(); 953 originator = packet_get_string(NULL); 954 originator_port = packet_get_int(); 955 packet_check_eom(); 956 957 debug("server_request_direct_tcpip: originator %s port %d, target %s " 958 "port %d", originator, originator_port, target, target_port); 959 960 /* XXX check permission */ 961 c = channel_connect_to(target, target_port, 962 "direct-tcpip", "direct-tcpip"); 963 964 xfree(originator); 965 xfree(target); 966 967 return c; 968 } 969 970 static Channel * 971 server_request_tun(void) 972 { 973 Channel *c = NULL; 974 int mode, tun; 975 int sock; 976 977 mode = packet_get_int(); 978 switch (mode) { 979 case SSH_TUNMODE_POINTOPOINT: 980 case SSH_TUNMODE_ETHERNET: 981 break; 982 default: 983 packet_send_debug("Unsupported tunnel device mode."); 984 return NULL; 985 } 986 if ((options.permit_tun & mode) == 0) { 987 packet_send_debug("Server has rejected tunnel device " 988 "forwarding"); 989 return NULL; 990 } 991 992 tun = packet_get_int(); 993 if (forced_tun_device != -1) { 994 if (tun != SSH_TUNID_ANY && forced_tun_device != tun) 995 goto done; 996 tun = forced_tun_device; 997 } 998 sock = tun_open(tun, mode); 999 if (sock < 0) 1000 goto done; 1001 if (options.hpn_disabled) 1002 c = channel_new("tun", SSH_CHANNEL_OPEN, sock, sock, -1, 1003 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1); 1004 else 1005 c = channel_new("tun", SSH_CHANNEL_OPEN, sock, sock, -1, 1006 options.hpn_buffer_size, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1); 1007 c->datagram = 1; 1008 1009 done: 1010 if (c == NULL) 1011 packet_send_debug("Failed to open the tunnel device."); 1012 return c; 1013 } 1014 1015 static Channel * 1016 server_request_session(void) 1017 { 1018 Channel *c; 1019 1020 debug("input_session_request"); 1021 packet_check_eom(); 1022 1023 if (no_more_sessions) { 1024 packet_disconnect("Possible attack: attempt to open a session " 1025 "after additional sessions disabled"); 1026 } 1027 1028 /* 1029 * A server session has no fd to read or write until a 1030 * CHANNEL_REQUEST for a shell is made, so we set the type to 1031 * SSH_CHANNEL_LARVAL. Additionally, a callback for handling all 1032 * CHANNEL_REQUEST messages is registered. 1033 */ 1034 c = channel_new("session", SSH_CHANNEL_LARVAL, 1035 -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT, 1036 0, "server-session", 1); 1037 if ((options.tcp_rcv_buf_poll > 0) && (!options.hpn_disabled)) 1038 c->dynamic_window = 1; 1039 if (session_open(the_authctxt, c->self) != 1) { 1040 debug("session open failed, free channel %d", c->self); 1041 channel_free(c); 1042 return NULL; 1043 } 1044 channel_register_cleanup(c->self, session_close_by_channel, 0); 1045 return c; 1046 } 1047 1048 static void 1049 server_input_channel_open(int type, u_int32_t seq, void *ctxt) 1050 { 1051 Channel *c = NULL; 1052 char *ctype; 1053 int rchan; 1054 u_int rmaxpack, rwindow, len; 1055 1056 ctype = packet_get_string(&len); 1057 rchan = packet_get_int(); 1058 rwindow = packet_get_int(); 1059 rmaxpack = packet_get_int(); 1060 1061 debug("server_input_channel_open: ctype %s rchan %d win %d max %d", 1062 ctype, rchan, rwindow, rmaxpack); 1063 1064 if (strcmp(ctype, "session") == 0) { 1065 c = server_request_session(); 1066 } else if (strcmp(ctype, "direct-tcpip") == 0) { 1067 c = server_request_direct_tcpip(); 1068 } else if (strcmp(ctype, "tun@openssh.com") == 0) { 1069 c = server_request_tun(); 1070 } 1071 if (c != NULL) { 1072 debug("server_input_channel_open: confirm %s", ctype); 1073 c->remote_id = rchan; 1074 c->remote_window = rwindow; 1075 c->remote_maxpacket = rmaxpack; 1076 if (c->type != SSH_CHANNEL_CONNECTING) { 1077 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION); 1078 packet_put_int(c->remote_id); 1079 packet_put_int(c->self); 1080 packet_put_int(c->local_window); 1081 packet_put_int(c->local_maxpacket); 1082 packet_send(); 1083 } 1084 } else { 1085 debug("server_input_channel_open: failure %s", ctype); 1086 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE); 1087 packet_put_int(rchan); 1088 packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED); 1089 if (!(datafellows & SSH_BUG_OPENFAILURE)) { 1090 packet_put_cstring("open failed"); 1091 packet_put_cstring(""); 1092 } 1093 packet_send(); 1094 } 1095 xfree(ctype); 1096 } 1097 1098 static void 1099 server_input_global_request(int type, u_int32_t seq, void *ctxt) 1100 { 1101 char *rtype; 1102 int want_reply; 1103 int success = 0, allocated_listen_port = 0; 1104 1105 rtype = packet_get_string(NULL); 1106 want_reply = packet_get_char(); 1107 debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply); 1108 1109 /* -R style forwarding */ 1110 if (strcmp(rtype, "tcpip-forward") == 0) { 1111 struct passwd *pw; 1112 char *listen_address; 1113 u_short listen_port; 1114 1115 pw = the_authctxt->pw; 1116 if (pw == NULL || !the_authctxt->valid) 1117 fatal("server_input_global_request: no/invalid user"); 1118 listen_address = packet_get_string(NULL); 1119 listen_port = (u_short)packet_get_int(); 1120 debug("server_input_global_request: tcpip-forward listen %s port %d", 1121 listen_address, listen_port); 1122 1123 /* check permissions */ 1124 if (!options.allow_tcp_forwarding || 1125 no_port_forwarding_flag || 1126 (!want_reply && listen_port == 0) || 1127 (listen_port != 0 && listen_port < IPPORT_RESERVED && 1128 pw->pw_uid != 0)) { 1129 success = 0; 1130 packet_send_debug("Server has disabled port forwarding."); 1131 } else { 1132 /* Start listening on the port */ 1133 success = channel_setup_remote_fwd_listener( 1134 listen_address, listen_port, 1135 &allocated_listen_port, options.gateway_ports); 1136 } 1137 xfree(listen_address); 1138 } else if (strcmp(rtype, "cancel-tcpip-forward") == 0) { 1139 char *cancel_address; 1140 u_short cancel_port; 1141 1142 cancel_address = packet_get_string(NULL); 1143 cancel_port = (u_short)packet_get_int(); 1144 debug("%s: cancel-tcpip-forward addr %s port %d", __func__, 1145 cancel_address, cancel_port); 1146 1147 success = channel_cancel_rport_listener(cancel_address, 1148 cancel_port); 1149 xfree(cancel_address); 1150 } else if (strcmp(rtype, "no-more-sessions@openssh.com") == 0) { 1151 no_more_sessions = 1; 1152 success = 1; 1153 } 1154 if (want_reply) { 1155 packet_start(success ? 1156 SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE); 1157 if (success && allocated_listen_port > 0) 1158 packet_put_int(allocated_listen_port); 1159 packet_send(); 1160 packet_write_wait(); 1161 } 1162 xfree(rtype); 1163 } 1164 1165 static void 1166 server_input_channel_req(int type, u_int32_t seq, void *ctxt) 1167 { 1168 Channel *c; 1169 int id, reply, success = 0; 1170 char *rtype; 1171 1172 id = packet_get_int(); 1173 rtype = packet_get_string(NULL); 1174 reply = packet_get_char(); 1175 1176 debug("server_input_channel_req: channel %d request %s reply %d", 1177 id, rtype, reply); 1178 1179 if ((c = channel_lookup(id)) == NULL) 1180 packet_disconnect("server_input_channel_req: " 1181 "unknown channel %d", id); 1182 if (!strcmp(rtype, "eow@openssh.com")) { 1183 packet_check_eom(); 1184 chan_rcvd_eow(c); 1185 } else if ((c->type == SSH_CHANNEL_LARVAL || 1186 c->type == SSH_CHANNEL_OPEN) && strcmp(c->ctype, "session") == 0) 1187 success = session_input_channel_req(c, rtype); 1188 if (reply) { 1189 packet_start(success ? 1190 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE); 1191 packet_put_int(c->remote_id); 1192 packet_send(); 1193 } 1194 xfree(rtype); 1195 } 1196 1197 static void 1198 server_init_dispatch_20(void) 1199 { 1200 debug("server_init_dispatch_20"); 1201 dispatch_init(&dispatch_protocol_error); 1202 dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); 1203 dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data); 1204 dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); 1205 dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); 1206 dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open); 1207 dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 1208 dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 1209 dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req); 1210 dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); 1211 dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request); 1212 /* client_alive */ 1213 dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &server_input_keep_alive); 1214 dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_keep_alive); 1215 dispatch_set(SSH2_MSG_REQUEST_SUCCESS, &server_input_keep_alive); 1216 dispatch_set(SSH2_MSG_REQUEST_FAILURE, &server_input_keep_alive); 1217 /* rekeying */ 1218 dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); 1219 } 1220 static void 1221 server_init_dispatch_13(void) 1222 { 1223 debug("server_init_dispatch_13"); 1224 dispatch_init(NULL); 1225 dispatch_set(SSH_CMSG_EOF, &server_input_eof); 1226 dispatch_set(SSH_CMSG_STDIN_DATA, &server_input_stdin_data); 1227 dispatch_set(SSH_CMSG_WINDOW_SIZE, &server_input_window_size); 1228 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close); 1229 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation); 1230 dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data); 1231 dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 1232 dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 1233 dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open); 1234 } 1235 static void 1236 server_init_dispatch_15(void) 1237 { 1238 server_init_dispatch_13(); 1239 debug("server_init_dispatch_15"); 1240 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof); 1241 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_oclose); 1242 } 1243 static void 1244 server_init_dispatch(void) 1245 { 1246 if (compat20) 1247 server_init_dispatch_20(); 1248 else if (compat13) 1249 server_init_dispatch_13(); 1250 else 1251 server_init_dispatch_15(); 1252 } 1253