1 /* 2 * Author: Tatu Ylonen <ylo@cs.hut.fi> 3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 4 * All rights reserved 5 * Server main loop for handling the interactive session. 6 * 7 * As far as I am concerned, the code I have written for this software 8 * can be used freely for any purpose. Any derived versions of this 9 * software must be clearly marked as such, and if the derived work is 10 * incompatible with the protocol description in the RFC file, it must be 11 * called by a name other than "ssh" or "Secure Shell". 12 * 13 * SSH2 support by Markus Friedl. 14 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 15 * 16 * Redistribution and use in source and binary forms, with or without 17 * modification, are permitted provided that the following conditions 18 * are met: 19 * 1. Redistributions of source code must retain the above copyright 20 * notice, this list of conditions and the following disclaimer. 21 * 2. Redistributions in binary form must reproduce the above copyright 22 * notice, this list of conditions and the following disclaimer in the 23 * documentation and/or other materials provided with the distribution. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 26 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 27 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 28 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 29 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 30 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 31 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 32 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 33 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 34 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 35 */ 36 37 #include "includes.h" 38 RCSID("$OpenBSD: serverloop.c,v 1.101 2002/03/30 18:51:15 markus Exp $"); 39 40 #include "xmalloc.h" 41 #include "packet.h" 42 #include "buffer.h" 43 #include "log.h" 44 #include "servconf.h" 45 #include "sshpty.h" 46 #include "channels.h" 47 #include "compat.h" 48 #include "ssh1.h" 49 #include "ssh2.h" 50 #include "auth.h" 51 #include "session.h" 52 #include "dispatch.h" 53 #include "auth-options.h" 54 #include "serverloop.h" 55 #include "misc.h" 56 #include "kex.h" 57 58 extern ServerOptions options; 59 60 /* XXX */ 61 extern Kex *xxx_kex; 62 static Authctxt *xxx_authctxt; 63 64 static Buffer stdin_buffer; /* Buffer for stdin data. */ 65 static Buffer stdout_buffer; /* Buffer for stdout data. */ 66 static Buffer stderr_buffer; /* Buffer for stderr data. */ 67 static int fdin; /* Descriptor for stdin (for writing) */ 68 static int fdout; /* Descriptor for stdout (for reading); 69 May be same number as fdin. */ 70 static int fderr; /* Descriptor for stderr. May be -1. */ 71 static long stdin_bytes = 0; /* Number of bytes written to stdin. */ 72 static long stdout_bytes = 0; /* Number of stdout bytes sent to client. */ 73 static long stderr_bytes = 0; /* Number of stderr bytes sent to client. */ 74 static long fdout_bytes = 0; /* Number of stdout bytes read from program. */ 75 static int stdin_eof = 0; /* EOF message received from client. */ 76 static int fdout_eof = 0; /* EOF encountered reading from fdout. */ 77 static int fderr_eof = 0; /* EOF encountered readung from fderr. */ 78 static int fdin_is_tty = 0; /* fdin points to a tty. */ 79 static int connection_in; /* Connection to client (input). */ 80 static int connection_out; /* Connection to client (output). */ 81 static int connection_closed = 0; /* Connection to client closed. */ 82 static u_int buffer_high; /* "Soft" max buffer size. */ 83 static int client_alive_timeouts = 0; 84 85 /* 86 * This SIGCHLD kludge is used to detect when the child exits. The server 87 * will exit after that, as soon as forwarded connections have terminated. 88 */ 89 90 static volatile sig_atomic_t child_terminated = 0; /* The child has terminated. */ 91 92 /* prototypes */ 93 static void server_init_dispatch(void); 94 95 /* 96 * we write to this pipe if a SIGCHLD is caught in order to avoid 97 * the race between select() and child_terminated 98 */ 99 static int notify_pipe[2]; 100 static void 101 notify_setup(void) 102 { 103 if (pipe(notify_pipe) < 0) { 104 error("pipe(notify_pipe) failed %s", strerror(errno)); 105 } else if ((fcntl(notify_pipe[0], F_SETFD, 1) == -1) || 106 (fcntl(notify_pipe[1], F_SETFD, 1) == -1)) { 107 error("fcntl(notify_pipe, F_SETFD) failed %s", strerror(errno)); 108 close(notify_pipe[0]); 109 close(notify_pipe[1]); 110 } else { 111 set_nonblock(notify_pipe[0]); 112 set_nonblock(notify_pipe[1]); 113 return; 114 } 115 notify_pipe[0] = -1; /* read end */ 116 notify_pipe[1] = -1; /* write end */ 117 } 118 static void 119 notify_parent(void) 120 { 121 if (notify_pipe[1] != -1) 122 write(notify_pipe[1], "", 1); 123 } 124 static void 125 notify_prepare(fd_set *readset) 126 { 127 if (notify_pipe[0] != -1) 128 FD_SET(notify_pipe[0], readset); 129 } 130 static void 131 notify_done(fd_set *readset) 132 { 133 char c; 134 135 if (notify_pipe[0] != -1 && FD_ISSET(notify_pipe[0], readset)) 136 while (read(notify_pipe[0], &c, 1) != -1) 137 debug2("notify_done: reading"); 138 } 139 140 static void 141 sigchld_handler(int sig) 142 { 143 int save_errno = errno; 144 debug("Received SIGCHLD."); 145 child_terminated = 1; 146 signal(SIGCHLD, sigchld_handler); 147 notify_parent(); 148 errno = save_errno; 149 } 150 151 /* 152 * Make packets from buffered stderr data, and buffer it for sending 153 * to the client. 154 */ 155 static void 156 make_packets_from_stderr_data(void) 157 { 158 int len; 159 160 /* Send buffered stderr data to the client. */ 161 while (buffer_len(&stderr_buffer) > 0 && 162 packet_not_very_much_data_to_write()) { 163 len = buffer_len(&stderr_buffer); 164 if (packet_is_interactive()) { 165 if (len > 512) 166 len = 512; 167 } else { 168 /* Keep the packets at reasonable size. */ 169 if (len > packet_get_maxsize()) 170 len = packet_get_maxsize(); 171 } 172 packet_start(SSH_SMSG_STDERR_DATA); 173 packet_put_string(buffer_ptr(&stderr_buffer), len); 174 packet_send(); 175 buffer_consume(&stderr_buffer, len); 176 stderr_bytes += len; 177 } 178 } 179 180 /* 181 * Make packets from buffered stdout data, and buffer it for sending to the 182 * client. 183 */ 184 static void 185 make_packets_from_stdout_data(void) 186 { 187 int len; 188 189 /* Send buffered stdout data to the client. */ 190 while (buffer_len(&stdout_buffer) > 0 && 191 packet_not_very_much_data_to_write()) { 192 len = buffer_len(&stdout_buffer); 193 if (packet_is_interactive()) { 194 if (len > 512) 195 len = 512; 196 } else { 197 /* Keep the packets at reasonable size. */ 198 if (len > packet_get_maxsize()) 199 len = packet_get_maxsize(); 200 } 201 packet_start(SSH_SMSG_STDOUT_DATA); 202 packet_put_string(buffer_ptr(&stdout_buffer), len); 203 packet_send(); 204 buffer_consume(&stdout_buffer, len); 205 stdout_bytes += len; 206 } 207 } 208 209 static void 210 client_alive_check(void) 211 { 212 static int had_channel = 0; 213 int id; 214 215 id = channel_find_open(); 216 if (id == -1) { 217 if (!had_channel) 218 return; 219 packet_disconnect("No open channels after timeout!"); 220 } 221 had_channel = 1; 222 223 /* timeout, check to see how many we have had */ 224 if (++client_alive_timeouts > options.client_alive_count_max) 225 packet_disconnect("Timeout, your session not responding."); 226 227 /* 228 * send a bogus channel request with "wantreply", 229 * we should get back a failure 230 */ 231 channel_request_start(id, "keepalive@openssh.com", 1); 232 packet_send(); 233 } 234 235 /* 236 * Sleep in select() until we can do something. This will initialize the 237 * select masks. Upon return, the masks will indicate which descriptors 238 * have data or can accept data. Optionally, a maximum time can be specified 239 * for the duration of the wait (0 = infinite). 240 */ 241 static void 242 wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp, 243 int *nallocp, u_int max_time_milliseconds) 244 { 245 struct timeval tv, *tvp; 246 int ret; 247 int client_alive_scheduled = 0; 248 249 /* 250 * if using client_alive, set the max timeout accordingly, 251 * and indicate that this particular timeout was for client 252 * alive by setting the client_alive_scheduled flag. 253 * 254 * this could be randomized somewhat to make traffic 255 * analysis more difficult, but we're not doing it yet. 256 */ 257 if (compat20 && 258 max_time_milliseconds == 0 && options.client_alive_interval) { 259 client_alive_scheduled = 1; 260 max_time_milliseconds = options.client_alive_interval * 1000; 261 } 262 263 /* Allocate and update select() masks for channel descriptors. */ 264 channel_prepare_select(readsetp, writesetp, maxfdp, nallocp, 0); 265 266 if (compat20) { 267 #if 0 268 /* wrong: bad condition XXX */ 269 if (channel_not_very_much_buffered_data()) 270 #endif 271 FD_SET(connection_in, *readsetp); 272 } else { 273 /* 274 * Read packets from the client unless we have too much 275 * buffered stdin or channel data. 276 */ 277 if (buffer_len(&stdin_buffer) < buffer_high && 278 channel_not_very_much_buffered_data()) 279 FD_SET(connection_in, *readsetp); 280 /* 281 * If there is not too much data already buffered going to 282 * the client, try to get some more data from the program. 283 */ 284 if (packet_not_very_much_data_to_write()) { 285 if (!fdout_eof) 286 FD_SET(fdout, *readsetp); 287 if (!fderr_eof) 288 FD_SET(fderr, *readsetp); 289 } 290 /* 291 * If we have buffered data, try to write some of that data 292 * to the program. 293 */ 294 if (fdin != -1 && buffer_len(&stdin_buffer) > 0) 295 FD_SET(fdin, *writesetp); 296 } 297 notify_prepare(*readsetp); 298 299 /* 300 * If we have buffered packet data going to the client, mark that 301 * descriptor. 302 */ 303 if (packet_have_data_to_write()) 304 FD_SET(connection_out, *writesetp); 305 306 /* 307 * If child has terminated and there is enough buffer space to read 308 * from it, then read as much as is available and exit. 309 */ 310 if (child_terminated && packet_not_very_much_data_to_write()) 311 if (max_time_milliseconds == 0 || client_alive_scheduled) 312 max_time_milliseconds = 100; 313 314 if (max_time_milliseconds == 0) 315 tvp = NULL; 316 else { 317 tv.tv_sec = max_time_milliseconds / 1000; 318 tv.tv_usec = 1000 * (max_time_milliseconds % 1000); 319 tvp = &tv; 320 } 321 322 /* Wait for something to happen, or the timeout to expire. */ 323 ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp); 324 325 if (ret == -1) { 326 memset(*readsetp, 0, *nallocp); 327 memset(*writesetp, 0, *nallocp); 328 if (errno != EINTR) 329 error("select: %.100s", strerror(errno)); 330 } else if (ret == 0 && client_alive_scheduled) 331 client_alive_check(); 332 333 notify_done(*readsetp); 334 } 335 336 /* 337 * Processes input from the client and the program. Input data is stored 338 * in buffers and processed later. 339 */ 340 static void 341 process_input(fd_set * readset) 342 { 343 int len; 344 char buf[16384]; 345 346 /* Read and buffer any input data from the client. */ 347 if (FD_ISSET(connection_in, readset)) { 348 len = read(connection_in, buf, sizeof(buf)); 349 if (len == 0) { 350 verbose("Connection closed by remote host."); 351 connection_closed = 1; 352 if (compat20) 353 return; 354 fatal_cleanup(); 355 } else if (len < 0) { 356 if (errno != EINTR && errno != EAGAIN) { 357 verbose("Read error from remote host: %.100s", strerror(errno)); 358 fatal_cleanup(); 359 } 360 } else { 361 /* Buffer any received data. */ 362 packet_process_incoming(buf, len); 363 } 364 } 365 if (compat20) 366 return; 367 368 /* Read and buffer any available stdout data from the program. */ 369 if (!fdout_eof && FD_ISSET(fdout, readset)) { 370 len = read(fdout, buf, sizeof(buf)); 371 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 372 /* do nothing */ 373 } else if (len <= 0) { 374 fdout_eof = 1; 375 } else { 376 buffer_append(&stdout_buffer, buf, len); 377 fdout_bytes += len; 378 } 379 } 380 /* Read and buffer any available stderr data from the program. */ 381 if (!fderr_eof && FD_ISSET(fderr, readset)) { 382 len = read(fderr, buf, sizeof(buf)); 383 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 384 /* do nothing */ 385 } else if (len <= 0) { 386 fderr_eof = 1; 387 } else { 388 buffer_append(&stderr_buffer, buf, len); 389 } 390 } 391 } 392 393 /* 394 * Sends data from internal buffers to client program stdin. 395 */ 396 static void 397 process_output(fd_set * writeset) 398 { 399 struct termios tio; 400 u_char *data; 401 u_int dlen; 402 int len; 403 404 /* Write buffered data to program stdin. */ 405 if (!compat20 && fdin != -1 && FD_ISSET(fdin, writeset)) { 406 data = buffer_ptr(&stdin_buffer); 407 dlen = buffer_len(&stdin_buffer); 408 len = write(fdin, data, dlen); 409 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 410 /* do nothing */ 411 } else if (len <= 0) { 412 if (fdin != fdout) 413 close(fdin); 414 else 415 shutdown(fdin, SHUT_WR); /* We will no longer send. */ 416 fdin = -1; 417 } else { 418 /* Successful write. */ 419 if (fdin_is_tty && dlen >= 1 && data[0] != '\r' && 420 tcgetattr(fdin, &tio) == 0 && 421 !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) { 422 /* 423 * Simulate echo to reduce the impact of 424 * traffic analysis 425 */ 426 packet_send_ignore(len); 427 packet_send(); 428 } 429 /* Consume the data from the buffer. */ 430 buffer_consume(&stdin_buffer, len); 431 /* Update the count of bytes written to the program. */ 432 stdin_bytes += len; 433 } 434 } 435 /* Send any buffered packet data to the client. */ 436 if (FD_ISSET(connection_out, writeset)) 437 packet_write_poll(); 438 } 439 440 /* 441 * Wait until all buffered output has been sent to the client. 442 * This is used when the program terminates. 443 */ 444 static void 445 drain_output(void) 446 { 447 /* Send any buffered stdout data to the client. */ 448 if (buffer_len(&stdout_buffer) > 0) { 449 packet_start(SSH_SMSG_STDOUT_DATA); 450 packet_put_string(buffer_ptr(&stdout_buffer), 451 buffer_len(&stdout_buffer)); 452 packet_send(); 453 /* Update the count of sent bytes. */ 454 stdout_bytes += buffer_len(&stdout_buffer); 455 } 456 /* Send any buffered stderr data to the client. */ 457 if (buffer_len(&stderr_buffer) > 0) { 458 packet_start(SSH_SMSG_STDERR_DATA); 459 packet_put_string(buffer_ptr(&stderr_buffer), 460 buffer_len(&stderr_buffer)); 461 packet_send(); 462 /* Update the count of sent bytes. */ 463 stderr_bytes += buffer_len(&stderr_buffer); 464 } 465 /* Wait until all buffered data has been written to the client. */ 466 packet_write_wait(); 467 } 468 469 static void 470 process_buffered_input_packets(void) 471 { 472 dispatch_run(DISPATCH_NONBLOCK, NULL, compat20 ? xxx_kex : NULL); 473 } 474 475 /* 476 * Performs the interactive session. This handles data transmission between 477 * the client and the program. Note that the notion of stdin, stdout, and 478 * stderr in this function is sort of reversed: this function writes to 479 * stdin (of the child program), and reads from stdout and stderr (of the 480 * child program). 481 */ 482 void 483 server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg) 484 { 485 fd_set *readset = NULL, *writeset = NULL; 486 int max_fd = 0, nalloc = 0; 487 int wait_status; /* Status returned by wait(). */ 488 pid_t wait_pid; /* pid returned by wait(). */ 489 int waiting_termination = 0; /* Have displayed waiting close message. */ 490 u_int max_time_milliseconds; 491 u_int previous_stdout_buffer_bytes; 492 u_int stdout_buffer_bytes; 493 int type; 494 495 debug("Entering interactive session."); 496 497 /* Initialize the SIGCHLD kludge. */ 498 child_terminated = 0; 499 signal(SIGCHLD, sigchld_handler); 500 501 /* Initialize our global variables. */ 502 fdin = fdin_arg; 503 fdout = fdout_arg; 504 fderr = fderr_arg; 505 506 /* nonblocking IO */ 507 set_nonblock(fdin); 508 set_nonblock(fdout); 509 /* we don't have stderr for interactive terminal sessions, see below */ 510 if (fderr != -1) 511 set_nonblock(fderr); 512 513 if (!(datafellows & SSH_BUG_IGNOREMSG) && isatty(fdin)) 514 fdin_is_tty = 1; 515 516 connection_in = packet_get_connection_in(); 517 connection_out = packet_get_connection_out(); 518 519 notify_setup(); 520 521 previous_stdout_buffer_bytes = 0; 522 523 /* Set approximate I/O buffer size. */ 524 if (packet_is_interactive()) 525 buffer_high = 4096; 526 else 527 buffer_high = 64 * 1024; 528 529 #if 0 530 /* Initialize max_fd to the maximum of the known file descriptors. */ 531 max_fd = MAX(connection_in, connection_out); 532 max_fd = MAX(max_fd, fdin); 533 max_fd = MAX(max_fd, fdout); 534 if (fderr != -1) 535 max_fd = MAX(max_fd, fderr); 536 #endif 537 538 /* Initialize Initialize buffers. */ 539 buffer_init(&stdin_buffer); 540 buffer_init(&stdout_buffer); 541 buffer_init(&stderr_buffer); 542 543 /* 544 * If we have no separate fderr (which is the case when we have a pty 545 * - there we cannot make difference between data sent to stdout and 546 * stderr), indicate that we have seen an EOF from stderr. This way 547 * we don\'t need to check the descriptor everywhere. 548 */ 549 if (fderr == -1) 550 fderr_eof = 1; 551 552 server_init_dispatch(); 553 554 /* Main loop of the server for the interactive session mode. */ 555 for (;;) { 556 557 /* Process buffered packets from the client. */ 558 process_buffered_input_packets(); 559 560 /* 561 * If we have received eof, and there is no more pending 562 * input data, cause a real eof by closing fdin. 563 */ 564 if (stdin_eof && fdin != -1 && buffer_len(&stdin_buffer) == 0) { 565 if (fdin != fdout) 566 close(fdin); 567 else 568 shutdown(fdin, SHUT_WR); /* We will no longer send. */ 569 fdin = -1; 570 } 571 /* Make packets from buffered stderr data to send to the client. */ 572 make_packets_from_stderr_data(); 573 574 /* 575 * Make packets from buffered stdout data to send to the 576 * client. If there is very little to send, this arranges to 577 * not send them now, but to wait a short while to see if we 578 * are getting more data. This is necessary, as some systems 579 * wake up readers from a pty after each separate character. 580 */ 581 max_time_milliseconds = 0; 582 stdout_buffer_bytes = buffer_len(&stdout_buffer); 583 if (stdout_buffer_bytes != 0 && stdout_buffer_bytes < 256 && 584 stdout_buffer_bytes != previous_stdout_buffer_bytes) { 585 /* try again after a while */ 586 max_time_milliseconds = 10; 587 } else { 588 /* Send it now. */ 589 make_packets_from_stdout_data(); 590 } 591 previous_stdout_buffer_bytes = buffer_len(&stdout_buffer); 592 593 /* Send channel data to the client. */ 594 if (packet_not_very_much_data_to_write()) 595 channel_output_poll(); 596 597 /* 598 * Bail out of the loop if the program has closed its output 599 * descriptors, and we have no more data to send to the 600 * client, and there is no pending buffered data. 601 */ 602 if (fdout_eof && fderr_eof && !packet_have_data_to_write() && 603 buffer_len(&stdout_buffer) == 0 && buffer_len(&stderr_buffer) == 0) { 604 if (!channel_still_open()) 605 break; 606 if (!waiting_termination) { 607 const char *s = "Waiting for forwarded connections to terminate...\r\n"; 608 char *cp; 609 waiting_termination = 1; 610 buffer_append(&stderr_buffer, s, strlen(s)); 611 612 /* Display list of open channels. */ 613 cp = channel_open_message(); 614 buffer_append(&stderr_buffer, cp, strlen(cp)); 615 xfree(cp); 616 } 617 } 618 max_fd = MAX(connection_in, connection_out); 619 max_fd = MAX(max_fd, fdin); 620 max_fd = MAX(max_fd, fdout); 621 max_fd = MAX(max_fd, fderr); 622 max_fd = MAX(max_fd, notify_pipe[0]); 623 624 /* Sleep in select() until we can do something. */ 625 wait_until_can_do_something(&readset, &writeset, &max_fd, 626 &nalloc, max_time_milliseconds); 627 628 /* Process any channel events. */ 629 channel_after_select(readset, writeset); 630 631 /* Process input from the client and from program stdout/stderr. */ 632 process_input(readset); 633 634 /* Process output to the client and to program stdin. */ 635 process_output(writeset); 636 } 637 if (readset) 638 xfree(readset); 639 if (writeset) 640 xfree(writeset); 641 642 /* Cleanup and termination code. */ 643 644 /* Wait until all output has been sent to the client. */ 645 drain_output(); 646 647 debug("End of interactive session; stdin %ld, stdout (read %ld, sent %ld), stderr %ld bytes.", 648 stdin_bytes, fdout_bytes, stdout_bytes, stderr_bytes); 649 650 /* Free and clear the buffers. */ 651 buffer_free(&stdin_buffer); 652 buffer_free(&stdout_buffer); 653 buffer_free(&stderr_buffer); 654 655 /* Close the file descriptors. */ 656 if (fdout != -1) 657 close(fdout); 658 fdout = -1; 659 fdout_eof = 1; 660 if (fderr != -1) 661 close(fderr); 662 fderr = -1; 663 fderr_eof = 1; 664 if (fdin != -1) 665 close(fdin); 666 fdin = -1; 667 668 channel_free_all(); 669 670 /* We no longer want our SIGCHLD handler to be called. */ 671 signal(SIGCHLD, SIG_DFL); 672 673 while ((wait_pid = waitpid(-1, &wait_status, 0)) < 0) 674 if (errno != EINTR) 675 packet_disconnect("wait: %.100s", strerror(errno)); 676 if (wait_pid != pid) 677 error("Strange, wait returned pid %d, expected %d", 678 wait_pid, pid); 679 680 /* Check if it exited normally. */ 681 if (WIFEXITED(wait_status)) { 682 /* Yes, normal exit. Get exit status and send it to the client. */ 683 debug("Command exited with status %d.", WEXITSTATUS(wait_status)); 684 packet_start(SSH_SMSG_EXITSTATUS); 685 packet_put_int(WEXITSTATUS(wait_status)); 686 packet_send(); 687 packet_write_wait(); 688 689 /* 690 * Wait for exit confirmation. Note that there might be 691 * other packets coming before it; however, the program has 692 * already died so we just ignore them. The client is 693 * supposed to respond with the confirmation when it receives 694 * the exit status. 695 */ 696 do { 697 type = packet_read(); 698 } 699 while (type != SSH_CMSG_EXIT_CONFIRMATION); 700 701 debug("Received exit confirmation."); 702 return; 703 } 704 /* Check if the program terminated due to a signal. */ 705 if (WIFSIGNALED(wait_status)) 706 packet_disconnect("Command terminated on signal %d.", 707 WTERMSIG(wait_status)); 708 709 /* Some weird exit cause. Just exit. */ 710 packet_disconnect("wait returned status %04x.", wait_status); 711 /* NOTREACHED */ 712 } 713 714 static void 715 collect_children(void) 716 { 717 pid_t pid; 718 sigset_t oset, nset; 719 int status; 720 721 /* block SIGCHLD while we check for dead children */ 722 sigemptyset(&nset); 723 sigaddset(&nset, SIGCHLD); 724 sigprocmask(SIG_BLOCK, &nset, &oset); 725 if (child_terminated) { 726 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 727 (pid < 0 && errno == EINTR)) 728 if (pid > 0) 729 session_close_by_pid(pid, status); 730 child_terminated = 0; 731 } 732 sigprocmask(SIG_SETMASK, &oset, NULL); 733 } 734 735 void 736 server_loop2(Authctxt *authctxt) 737 { 738 fd_set *readset = NULL, *writeset = NULL; 739 int rekeying = 0, max_fd, nalloc = 0; 740 741 debug("Entering interactive session for SSH2."); 742 743 signal(SIGCHLD, sigchld_handler); 744 child_terminated = 0; 745 connection_in = packet_get_connection_in(); 746 connection_out = packet_get_connection_out(); 747 748 notify_setup(); 749 750 max_fd = MAX(connection_in, connection_out); 751 max_fd = MAX(max_fd, notify_pipe[0]); 752 753 xxx_authctxt = authctxt; 754 755 server_init_dispatch(); 756 757 for (;;) { 758 process_buffered_input_packets(); 759 760 rekeying = (xxx_kex != NULL && !xxx_kex->done); 761 762 if (!rekeying && packet_not_very_much_data_to_write()) 763 channel_output_poll(); 764 wait_until_can_do_something(&readset, &writeset, &max_fd, 765 &nalloc, 0); 766 767 collect_children(); 768 if (!rekeying) 769 channel_after_select(readset, writeset); 770 process_input(readset); 771 if (connection_closed) 772 break; 773 process_output(writeset); 774 } 775 collect_children(); 776 777 if (readset) 778 xfree(readset); 779 if (writeset) 780 xfree(writeset); 781 782 /* free all channels, no more reads and writes */ 783 channel_free_all(); 784 785 /* free remaining sessions, e.g. remove wtmp entries */ 786 session_destroy_all(NULL); 787 } 788 789 static void 790 server_input_channel_failure(int type, u_int32_t seq, void *ctxt) 791 { 792 debug("Got CHANNEL_FAILURE for keepalive"); 793 /* 794 * reset timeout, since we got a sane answer from the client. 795 * even if this was generated by something other than 796 * the bogus CHANNEL_REQUEST we send for keepalives. 797 */ 798 client_alive_timeouts = 0; 799 } 800 801 802 static void 803 server_input_stdin_data(int type, u_int32_t seq, void *ctxt) 804 { 805 char *data; 806 u_int data_len; 807 808 /* Stdin data from the client. Append it to the buffer. */ 809 /* Ignore any data if the client has closed stdin. */ 810 if (fdin == -1) 811 return; 812 data = packet_get_string(&data_len); 813 packet_check_eom(); 814 buffer_append(&stdin_buffer, data, data_len); 815 memset(data, 0, data_len); 816 xfree(data); 817 } 818 819 static void 820 server_input_eof(int type, u_int32_t seq, void *ctxt) 821 { 822 /* 823 * Eof from the client. The stdin descriptor to the 824 * program will be closed when all buffered data has 825 * drained. 826 */ 827 debug("EOF received for stdin."); 828 packet_check_eom(); 829 stdin_eof = 1; 830 } 831 832 static void 833 server_input_window_size(int type, u_int32_t seq, void *ctxt) 834 { 835 int row = packet_get_int(); 836 int col = packet_get_int(); 837 int xpixel = packet_get_int(); 838 int ypixel = packet_get_int(); 839 840 debug("Window change received."); 841 packet_check_eom(); 842 if (fdin != -1) 843 pty_change_window_size(fdin, row, col, xpixel, ypixel); 844 } 845 846 static Channel * 847 server_request_direct_tcpip(char *ctype) 848 { 849 Channel *c; 850 int sock; 851 char *target, *originator; 852 int target_port, originator_port; 853 854 target = packet_get_string(NULL); 855 target_port = packet_get_int(); 856 originator = packet_get_string(NULL); 857 originator_port = packet_get_int(); 858 packet_check_eom(); 859 860 debug("server_request_direct_tcpip: originator %s port %d, target %s port %d", 861 originator, originator_port, target, target_port); 862 863 /* XXX check permission */ 864 sock = channel_connect_to(target, target_port); 865 xfree(target); 866 xfree(originator); 867 if (sock < 0) 868 return NULL; 869 c = channel_new(ctype, SSH_CHANNEL_CONNECTING, 870 sock, sock, -1, CHAN_TCP_WINDOW_DEFAULT, 871 CHAN_TCP_PACKET_DEFAULT, 0, xstrdup("direct-tcpip"), 1); 872 return c; 873 } 874 875 static Channel * 876 server_request_session(char *ctype) 877 { 878 Channel *c; 879 880 debug("input_session_request"); 881 packet_check_eom(); 882 /* 883 * A server session has no fd to read or write until a 884 * CHANNEL_REQUEST for a shell is made, so we set the type to 885 * SSH_CHANNEL_LARVAL. Additionally, a callback for handling all 886 * CHANNEL_REQUEST messages is registered. 887 */ 888 c = channel_new(ctype, SSH_CHANNEL_LARVAL, 889 -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT, 890 0, xstrdup("server-session"), 1); 891 if (session_open(xxx_authctxt, c->self) != 1) { 892 debug("session open failed, free channel %d", c->self); 893 channel_free(c); 894 return NULL; 895 } 896 channel_register_cleanup(c->self, session_close_by_channel); 897 return c; 898 } 899 900 static void 901 server_input_channel_open(int type, u_int32_t seq, void *ctxt) 902 { 903 Channel *c = NULL; 904 char *ctype; 905 u_int len; 906 int rchan; 907 int rmaxpack; 908 int rwindow; 909 910 ctype = packet_get_string(&len); 911 rchan = packet_get_int(); 912 rwindow = packet_get_int(); 913 rmaxpack = packet_get_int(); 914 915 debug("server_input_channel_open: ctype %s rchan %d win %d max %d", 916 ctype, rchan, rwindow, rmaxpack); 917 918 if (strcmp(ctype, "session") == 0) { 919 c = server_request_session(ctype); 920 } else if (strcmp(ctype, "direct-tcpip") == 0) { 921 c = server_request_direct_tcpip(ctype); 922 } 923 if (c != NULL) { 924 debug("server_input_channel_open: confirm %s", ctype); 925 c->remote_id = rchan; 926 c->remote_window = rwindow; 927 c->remote_maxpacket = rmaxpack; 928 if (c->type != SSH_CHANNEL_CONNECTING) { 929 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION); 930 packet_put_int(c->remote_id); 931 packet_put_int(c->self); 932 packet_put_int(c->local_window); 933 packet_put_int(c->local_maxpacket); 934 packet_send(); 935 } 936 } else { 937 debug("server_input_channel_open: failure %s", ctype); 938 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE); 939 packet_put_int(rchan); 940 packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED); 941 if (!(datafellows & SSH_BUG_OPENFAILURE)) { 942 packet_put_cstring("open failed"); 943 packet_put_cstring(""); 944 } 945 packet_send(); 946 } 947 xfree(ctype); 948 } 949 950 static void 951 server_input_global_request(int type, u_int32_t seq, void *ctxt) 952 { 953 char *rtype; 954 int want_reply; 955 int success = 0; 956 957 rtype = packet_get_string(NULL); 958 want_reply = packet_get_char(); 959 debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply); 960 961 /* -R style forwarding */ 962 if (strcmp(rtype, "tcpip-forward") == 0) { 963 struct passwd *pw; 964 char *listen_address; 965 u_short listen_port; 966 967 pw = auth_get_user(); 968 if (pw == NULL) 969 fatal("server_input_global_request: no user"); 970 listen_address = packet_get_string(NULL); /* XXX currently ignored */ 971 listen_port = (u_short)packet_get_int(); 972 debug("server_input_global_request: tcpip-forward listen %s port %d", 973 listen_address, listen_port); 974 975 /* check permissions */ 976 if (!options.allow_tcp_forwarding || 977 no_port_forwarding_flag || 978 (listen_port < IPPORT_RESERVED && pw->pw_uid != 0)) { 979 success = 0; 980 packet_send_debug("Server has disabled port forwarding."); 981 } else { 982 /* Start listening on the port */ 983 success = channel_setup_remote_fwd_listener( 984 listen_address, listen_port, options.gateway_ports); 985 } 986 xfree(listen_address); 987 } 988 if (want_reply) { 989 packet_start(success ? 990 SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE); 991 packet_send(); 992 packet_write_wait(); 993 } 994 xfree(rtype); 995 } 996 static void 997 server_input_channel_req(int type, u_int32_t seq, void *ctxt) 998 { 999 Channel *c; 1000 int id, reply, success = 0; 1001 char *rtype; 1002 1003 id = packet_get_int(); 1004 rtype = packet_get_string(NULL); 1005 reply = packet_get_char(); 1006 1007 debug("server_input_channel_req: channel %d request %s reply %d", 1008 id, rtype, reply); 1009 1010 if ((c = channel_lookup(id)) == NULL) 1011 packet_disconnect("server_input_channel_req: " 1012 "unknown channel %d", id); 1013 if (c->type == SSH_CHANNEL_LARVAL || c->type == SSH_CHANNEL_OPEN) 1014 success = session_input_channel_req(c, rtype); 1015 if (reply) { 1016 packet_start(success ? 1017 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE); 1018 packet_put_int(c->remote_id); 1019 packet_send(); 1020 } 1021 xfree(rtype); 1022 } 1023 1024 static void 1025 server_init_dispatch_20(void) 1026 { 1027 debug("server_init_dispatch_20"); 1028 dispatch_init(&dispatch_protocol_error); 1029 dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); 1030 dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data); 1031 dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); 1032 dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); 1033 dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open); 1034 dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 1035 dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 1036 dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req); 1037 dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); 1038 dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request); 1039 /* client_alive */ 1040 dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_channel_failure); 1041 /* rekeying */ 1042 dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); 1043 } 1044 static void 1045 server_init_dispatch_13(void) 1046 { 1047 debug("server_init_dispatch_13"); 1048 dispatch_init(NULL); 1049 dispatch_set(SSH_CMSG_EOF, &server_input_eof); 1050 dispatch_set(SSH_CMSG_STDIN_DATA, &server_input_stdin_data); 1051 dispatch_set(SSH_CMSG_WINDOW_SIZE, &server_input_window_size); 1052 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close); 1053 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation); 1054 dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data); 1055 dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 1056 dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 1057 dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open); 1058 } 1059 static void 1060 server_init_dispatch_15(void) 1061 { 1062 server_init_dispatch_13(); 1063 debug("server_init_dispatch_15"); 1064 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof); 1065 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_oclose); 1066 } 1067 static void 1068 server_init_dispatch(void) 1069 { 1070 if (compat20) 1071 server_init_dispatch_20(); 1072 else if (compat13) 1073 server_init_dispatch_13(); 1074 else 1075 server_init_dispatch_15(); 1076 } 1077