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 1.103 2002/06/24 14:33:27 markus Exp $"); 39 RCSID("$FreeBSD$"); 40 41 #include "xmalloc.h" 42 #include "packet.h" 43 #include "buffer.h" 44 #include "log.h" 45 #include "servconf.h" 46 #include "sshpty.h" 47 #include "channels.h" 48 #include "compat.h" 49 #include "ssh1.h" 50 #include "ssh2.h" 51 #include "auth.h" 52 #include "session.h" 53 #include "dispatch.h" 54 #include "auth-options.h" 55 #include "serverloop.h" 56 #include "misc.h" 57 #include "kex.h" 58 59 extern ServerOptions options; 60 61 /* XXX */ 62 extern Kex *xxx_kex; 63 static Authctxt *xxx_authctxt; 64 65 static Buffer stdin_buffer; /* Buffer for stdin data. */ 66 static Buffer stdout_buffer; /* Buffer for stdout data. */ 67 static Buffer stderr_buffer; /* Buffer for stderr data. */ 68 static int fdin; /* Descriptor for stdin (for writing) */ 69 static int fdout; /* Descriptor for stdout (for reading); 70 May be same number as fdin. */ 71 static int fderr; /* Descriptor for stderr. May be -1. */ 72 static long stdin_bytes = 0; /* Number of bytes written to stdin. */ 73 static long stdout_bytes = 0; /* Number of stdout bytes sent to client. */ 74 static long stderr_bytes = 0; /* Number of stderr bytes sent to client. */ 75 static long fdout_bytes = 0; /* Number of stdout bytes read from program. */ 76 static int stdin_eof = 0; /* EOF message received from client. */ 77 static int fdout_eof = 0; /* EOF encountered reading from fdout. */ 78 static int fderr_eof = 0; /* EOF encountered readung from fderr. */ 79 static int fdin_is_tty = 0; /* fdin points to a tty. */ 80 static int connection_in; /* Connection to client (input). */ 81 static int connection_out; /* Connection to client (output). */ 82 static int connection_closed = 0; /* Connection to client closed. */ 83 static u_int buffer_high; /* "Soft" max buffer size. */ 84 static int client_alive_timeouts = 0; 85 86 /* 87 * This SIGCHLD kludge is used to detect when the child exits. The server 88 * will exit after that, as soon as forwarded connections have terminated. 89 */ 90 91 static volatile sig_atomic_t child_terminated = 0; /* The child has terminated. */ 92 93 /* prototypes */ 94 static void server_init_dispatch(void); 95 96 /* 97 * we write to this pipe if a SIGCHLD is caught in order to avoid 98 * the race between select() and child_terminated 99 */ 100 static int notify_pipe[2]; 101 static void 102 notify_setup(void) 103 { 104 if (pipe(notify_pipe) < 0) { 105 error("pipe(notify_pipe) failed %s", strerror(errno)); 106 } else if ((fcntl(notify_pipe[0], F_SETFD, 1) == -1) || 107 (fcntl(notify_pipe[1], F_SETFD, 1) == -1)) { 108 error("fcntl(notify_pipe, F_SETFD) failed %s", strerror(errno)); 109 close(notify_pipe[0]); 110 close(notify_pipe[1]); 111 } else { 112 set_nonblock(notify_pipe[0]); 113 set_nonblock(notify_pipe[1]); 114 return; 115 } 116 notify_pipe[0] = -1; /* read end */ 117 notify_pipe[1] = -1; /* write end */ 118 } 119 static void 120 notify_parent(void) 121 { 122 if (notify_pipe[1] != -1) 123 write(notify_pipe[1], "", 1); 124 } 125 static void 126 notify_prepare(fd_set *readset) 127 { 128 if (notify_pipe[0] != -1) 129 FD_SET(notify_pipe[0], readset); 130 } 131 static void 132 notify_done(fd_set *readset) 133 { 134 char c; 135 136 if (notify_pipe[0] != -1 && FD_ISSET(notify_pipe[0], readset)) 137 while (read(notify_pipe[0], &c, 1) != -1) 138 debug2("notify_done: reading"); 139 } 140 141 static void 142 sigchld_handler(int sig) 143 { 144 int save_errno = errno; 145 debug("Received SIGCHLD."); 146 child_terminated = 1; 147 mysignal(SIGCHLD, sigchld_handler); 148 notify_parent(); 149 errno = save_errno; 150 } 151 152 /* 153 * Make packets from buffered stderr data, and buffer it for sending 154 * to the client. 155 */ 156 static void 157 make_packets_from_stderr_data(void) 158 { 159 int len; 160 161 /* Send buffered stderr data to the client. */ 162 while (buffer_len(&stderr_buffer) > 0 && 163 packet_not_very_much_data_to_write()) { 164 len = buffer_len(&stderr_buffer); 165 if (packet_is_interactive()) { 166 if (len > 512) 167 len = 512; 168 } else { 169 /* Keep the packets at reasonable size. */ 170 if (len > packet_get_maxsize()) 171 len = packet_get_maxsize(); 172 } 173 packet_start(SSH_SMSG_STDERR_DATA); 174 packet_put_string(buffer_ptr(&stderr_buffer), len); 175 packet_send(); 176 buffer_consume(&stderr_buffer, len); 177 stderr_bytes += len; 178 } 179 } 180 181 /* 182 * Make packets from buffered stdout data, and buffer it for sending to the 183 * client. 184 */ 185 static void 186 make_packets_from_stdout_data(void) 187 { 188 int len; 189 190 /* Send buffered stdout data to the client. */ 191 while (buffer_len(&stdout_buffer) > 0 && 192 packet_not_very_much_data_to_write()) { 193 len = buffer_len(&stdout_buffer); 194 if (packet_is_interactive()) { 195 if (len > 512) 196 len = 512; 197 } else { 198 /* Keep the packets at reasonable size. */ 199 if (len > packet_get_maxsize()) 200 len = packet_get_maxsize(); 201 } 202 packet_start(SSH_SMSG_STDOUT_DATA); 203 packet_put_string(buffer_ptr(&stdout_buffer), len); 204 packet_send(); 205 buffer_consume(&stdout_buffer, len); 206 stdout_bytes += len; 207 } 208 } 209 210 static void 211 client_alive_check(void) 212 { 213 static int had_channel = 0; 214 int id; 215 216 id = channel_find_open(); 217 if (id == -1) { 218 if (!had_channel) 219 return; 220 packet_disconnect("No open channels after timeout!"); 221 } 222 had_channel = 1; 223 224 /* timeout, check to see how many we have had */ 225 if (++client_alive_timeouts > options.client_alive_count_max) 226 packet_disconnect("Timeout, your session not responding."); 227 228 /* 229 * send a bogus channel request with "wantreply", 230 * we should get back a failure 231 */ 232 channel_request_start(id, "keepalive@openssh.com", 1); 233 packet_send(); 234 } 235 236 /* 237 * Sleep in select() until we can do something. This will initialize the 238 * select masks. Upon return, the masks will indicate which descriptors 239 * have data or can accept data. Optionally, a maximum time can be specified 240 * for the duration of the wait (0 = infinite). 241 */ 242 static void 243 wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp, 244 int *nallocp, u_int max_time_milliseconds) 245 { 246 struct timeval tv, *tvp; 247 int ret; 248 int client_alive_scheduled = 0; 249 250 /* 251 * if using client_alive, set the max timeout accordingly, 252 * and indicate that this particular timeout was for client 253 * alive by setting the client_alive_scheduled flag. 254 * 255 * this could be randomized somewhat to make traffic 256 * analysis more difficult, but we're not doing it yet. 257 */ 258 if (compat20 && 259 max_time_milliseconds == 0 && options.client_alive_interval) { 260 client_alive_scheduled = 1; 261 max_time_milliseconds = options.client_alive_interval * 1000; 262 } 263 264 /* Allocate and update select() masks for channel descriptors. */ 265 channel_prepare_select(readsetp, writesetp, maxfdp, nallocp, 0); 266 267 if (compat20) { 268 #if 0 269 /* wrong: bad condition XXX */ 270 if (channel_not_very_much_buffered_data()) 271 #endif 272 FD_SET(connection_in, *readsetp); 273 } else { 274 /* 275 * Read packets from the client unless we have too much 276 * buffered stdin or channel data. 277 */ 278 if (buffer_len(&stdin_buffer) < buffer_high && 279 channel_not_very_much_buffered_data()) 280 FD_SET(connection_in, *readsetp); 281 /* 282 * If there is not too much data already buffered going to 283 * the client, try to get some more data from the program. 284 */ 285 if (packet_not_very_much_data_to_write()) { 286 if (!fdout_eof) 287 FD_SET(fdout, *readsetp); 288 if (!fderr_eof) 289 FD_SET(fderr, *readsetp); 290 } 291 /* 292 * If we have buffered data, try to write some of that data 293 * to the program. 294 */ 295 if (fdin != -1 && buffer_len(&stdin_buffer) > 0) 296 FD_SET(fdin, *writesetp); 297 } 298 notify_prepare(*readsetp); 299 300 /* 301 * If we have buffered packet data going to the client, mark that 302 * descriptor. 303 */ 304 if (packet_have_data_to_write()) 305 FD_SET(connection_out, *writesetp); 306 307 /* 308 * If child has terminated and there is enough buffer space to read 309 * from it, then read as much as is available and exit. 310 */ 311 if (child_terminated && packet_not_very_much_data_to_write()) 312 if (max_time_milliseconds == 0 || client_alive_scheduled) 313 max_time_milliseconds = 100; 314 315 if (max_time_milliseconds == 0) 316 tvp = NULL; 317 else { 318 tv.tv_sec = max_time_milliseconds / 1000; 319 tv.tv_usec = 1000 * (max_time_milliseconds % 1000); 320 tvp = &tv; 321 } 322 323 /* Wait for something to happen, or the timeout to expire. */ 324 ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp); 325 326 if (ret == -1) { 327 memset(*readsetp, 0, *nallocp); 328 memset(*writesetp, 0, *nallocp); 329 if (errno != EINTR) 330 error("select: %.100s", strerror(errno)); 331 } else if (ret == 0 && client_alive_scheduled) 332 client_alive_check(); 333 334 notify_done(*readsetp); 335 } 336 337 /* 338 * Processes input from the client and the program. Input data is stored 339 * in buffers and processed later. 340 */ 341 static void 342 process_input(fd_set * readset) 343 { 344 int len; 345 char buf[16384]; 346 347 /* Read and buffer any input data from the client. */ 348 if (FD_ISSET(connection_in, readset)) { 349 len = read(connection_in, buf, sizeof(buf)); 350 if (len == 0) { 351 verbose("Connection closed by remote host."); 352 connection_closed = 1; 353 if (compat20) 354 return; 355 fatal_cleanup(); 356 } else if (len < 0) { 357 if (errno != EINTR && errno != EAGAIN) { 358 verbose("Read error from remote host: %.100s", strerror(errno)); 359 fatal_cleanup(); 360 } 361 } else { 362 /* Buffer any received data. */ 363 packet_process_incoming(buf, len); 364 } 365 } 366 if (compat20) 367 return; 368 369 /* Read and buffer any available stdout data from the program. */ 370 if (!fdout_eof && FD_ISSET(fdout, readset)) { 371 len = read(fdout, buf, sizeof(buf)); 372 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 373 /* do nothing */ 374 } else if (len <= 0) { 375 fdout_eof = 1; 376 } else { 377 buffer_append(&stdout_buffer, buf, len); 378 fdout_bytes += len; 379 } 380 } 381 /* Read and buffer any available stderr data from the program. */ 382 if (!fderr_eof && FD_ISSET(fderr, readset)) { 383 len = read(fderr, buf, sizeof(buf)); 384 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 385 /* do nothing */ 386 } else if (len <= 0) { 387 fderr_eof = 1; 388 } else { 389 buffer_append(&stderr_buffer, buf, len); 390 } 391 } 392 } 393 394 /* 395 * Sends data from internal buffers to client program stdin. 396 */ 397 static void 398 process_output(fd_set * writeset) 399 { 400 struct termios tio; 401 u_char *data; 402 u_int dlen; 403 int len; 404 405 /* Write buffered data to program stdin. */ 406 if (!compat20 && fdin != -1 && FD_ISSET(fdin, writeset)) { 407 data = buffer_ptr(&stdin_buffer); 408 dlen = buffer_len(&stdin_buffer); 409 len = write(fdin, data, dlen); 410 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 411 /* do nothing */ 412 } else if (len <= 0) { 413 if (fdin != fdout) 414 close(fdin); 415 else 416 shutdown(fdin, SHUT_WR); /* We will no longer send. */ 417 fdin = -1; 418 } else { 419 /* Successful write. */ 420 if (fdin_is_tty && dlen >= 1 && data[0] != '\r' && 421 tcgetattr(fdin, &tio) == 0 && 422 !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) { 423 /* 424 * Simulate echo to reduce the impact of 425 * traffic analysis 426 */ 427 packet_send_ignore(len); 428 packet_send(); 429 } 430 /* Consume the data from the buffer. */ 431 buffer_consume(&stdin_buffer, len); 432 /* Update the count of bytes written to the program. */ 433 stdin_bytes += len; 434 } 435 } 436 /* Send any buffered packet data to the client. */ 437 if (FD_ISSET(connection_out, writeset)) 438 packet_write_poll(); 439 } 440 441 /* 442 * Wait until all buffered output has been sent to the client. 443 * This is used when the program terminates. 444 */ 445 static void 446 drain_output(void) 447 { 448 /* Send any buffered stdout data to the client. */ 449 if (buffer_len(&stdout_buffer) > 0) { 450 packet_start(SSH_SMSG_STDOUT_DATA); 451 packet_put_string(buffer_ptr(&stdout_buffer), 452 buffer_len(&stdout_buffer)); 453 packet_send(); 454 /* Update the count of sent bytes. */ 455 stdout_bytes += buffer_len(&stdout_buffer); 456 } 457 /* Send any buffered stderr data to the client. */ 458 if (buffer_len(&stderr_buffer) > 0) { 459 packet_start(SSH_SMSG_STDERR_DATA); 460 packet_put_string(buffer_ptr(&stderr_buffer), 461 buffer_len(&stderr_buffer)); 462 packet_send(); 463 /* Update the count of sent bytes. */ 464 stderr_bytes += buffer_len(&stderr_buffer); 465 } 466 /* Wait until all buffered data has been written to the client. */ 467 packet_write_wait(); 468 } 469 470 static void 471 process_buffered_input_packets(void) 472 { 473 dispatch_run(DISPATCH_NONBLOCK, NULL, compat20 ? xxx_kex : NULL); 474 } 475 476 /* 477 * Performs the interactive session. This handles data transmission between 478 * the client and the program. Note that the notion of stdin, stdout, and 479 * stderr in this function is sort of reversed: this function writes to 480 * stdin (of the child program), and reads from stdout and stderr (of the 481 * child program). 482 */ 483 void 484 server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg) 485 { 486 fd_set *readset = NULL, *writeset = NULL; 487 int max_fd = 0, nalloc = 0; 488 int wait_status; /* Status returned by wait(). */ 489 pid_t wait_pid; /* pid returned by wait(). */ 490 int waiting_termination = 0; /* Have displayed waiting close message. */ 491 u_int max_time_milliseconds; 492 u_int previous_stdout_buffer_bytes; 493 u_int stdout_buffer_bytes; 494 int type; 495 496 debug("Entering interactive session."); 497 498 /* Initialize the SIGCHLD kludge. */ 499 child_terminated = 0; 500 mysignal(SIGCHLD, sigchld_handler); 501 502 /* Initialize our global variables. */ 503 fdin = fdin_arg; 504 fdout = fdout_arg; 505 fderr = fderr_arg; 506 507 /* nonblocking IO */ 508 set_nonblock(fdin); 509 set_nonblock(fdout); 510 /* we don't have stderr for interactive terminal sessions, see below */ 511 if (fderr != -1) 512 set_nonblock(fderr); 513 514 if (!(datafellows & SSH_BUG_IGNOREMSG) && isatty(fdin)) 515 fdin_is_tty = 1; 516 517 connection_in = packet_get_connection_in(); 518 connection_out = packet_get_connection_out(); 519 520 notify_setup(); 521 522 previous_stdout_buffer_bytes = 0; 523 524 /* Set approximate I/O buffer size. */ 525 if (packet_is_interactive()) 526 buffer_high = 4096; 527 else 528 buffer_high = 64 * 1024; 529 530 #if 0 531 /* Initialize max_fd to the maximum of the known file descriptors. */ 532 max_fd = MAX(connection_in, connection_out); 533 max_fd = MAX(max_fd, fdin); 534 max_fd = MAX(max_fd, fdout); 535 if (fderr != -1) 536 max_fd = MAX(max_fd, fderr); 537 #endif 538 539 /* Initialize Initialize buffers. */ 540 buffer_init(&stdin_buffer); 541 buffer_init(&stdout_buffer); 542 buffer_init(&stderr_buffer); 543 544 /* 545 * If we have no separate fderr (which is the case when we have a pty 546 * - there we cannot make difference between data sent to stdout and 547 * stderr), indicate that we have seen an EOF from stderr. This way 548 * we don\'t need to check the descriptor everywhere. 549 */ 550 if (fderr == -1) 551 fderr_eof = 1; 552 553 server_init_dispatch(); 554 555 /* Main loop of the server for the interactive session mode. */ 556 for (;;) { 557 558 /* Process buffered packets from the client. */ 559 process_buffered_input_packets(); 560 561 /* 562 * If we have received eof, and there is no more pending 563 * input data, cause a real eof by closing fdin. 564 */ 565 if (stdin_eof && fdin != -1 && buffer_len(&stdin_buffer) == 0) { 566 if (fdin != fdout) 567 close(fdin); 568 else 569 shutdown(fdin, SHUT_WR); /* We will no longer send. */ 570 fdin = -1; 571 } 572 /* Make packets from buffered stderr data to send to the client. */ 573 make_packets_from_stderr_data(); 574 575 /* 576 * Make packets from buffered stdout data to send to the 577 * client. If there is very little to send, this arranges to 578 * not send them now, but to wait a short while to see if we 579 * are getting more data. This is necessary, as some systems 580 * wake up readers from a pty after each separate character. 581 */ 582 max_time_milliseconds = 0; 583 stdout_buffer_bytes = buffer_len(&stdout_buffer); 584 if (stdout_buffer_bytes != 0 && stdout_buffer_bytes < 256 && 585 stdout_buffer_bytes != previous_stdout_buffer_bytes) { 586 /* try again after a while */ 587 max_time_milliseconds = 10; 588 } else { 589 /* Send it now. */ 590 make_packets_from_stdout_data(); 591 } 592 previous_stdout_buffer_bytes = buffer_len(&stdout_buffer); 593 594 /* Send channel data to the client. */ 595 if (packet_not_very_much_data_to_write()) 596 channel_output_poll(); 597 598 /* 599 * Bail out of the loop if the program has closed its output 600 * descriptors, and we have no more data to send to the 601 * client, and there is no pending buffered data. 602 */ 603 if (fdout_eof && fderr_eof && !packet_have_data_to_write() && 604 buffer_len(&stdout_buffer) == 0 && buffer_len(&stderr_buffer) == 0) { 605 if (!channel_still_open()) 606 break; 607 if (!waiting_termination) { 608 const char *s = "Waiting for forwarded connections to terminate...\r\n"; 609 char *cp; 610 waiting_termination = 1; 611 buffer_append(&stderr_buffer, s, strlen(s)); 612 613 /* Display list of open channels. */ 614 cp = channel_open_message(); 615 buffer_append(&stderr_buffer, cp, strlen(cp)); 616 xfree(cp); 617 } 618 } 619 max_fd = MAX(connection_in, connection_out); 620 max_fd = MAX(max_fd, fdin); 621 max_fd = MAX(max_fd, fdout); 622 max_fd = MAX(max_fd, fderr); 623 max_fd = MAX(max_fd, notify_pipe[0]); 624 625 /* Sleep in select() until we can do something. */ 626 wait_until_can_do_something(&readset, &writeset, &max_fd, 627 &nalloc, max_time_milliseconds); 628 629 /* Process any channel events. */ 630 channel_after_select(readset, writeset); 631 632 /* Process input from the client and from program stdout/stderr. */ 633 process_input(readset); 634 635 /* Process output to the client and to program stdin. */ 636 process_output(writeset); 637 } 638 if (readset) 639 xfree(readset); 640 if (writeset) 641 xfree(writeset); 642 643 /* Cleanup and termination code. */ 644 645 /* Wait until all output has been sent to the client. */ 646 drain_output(); 647 648 debug("End of interactive session; stdin %ld, stdout (read %ld, sent %ld), stderr %ld bytes.", 649 stdin_bytes, fdout_bytes, stdout_bytes, stderr_bytes); 650 651 /* Free and clear the buffers. */ 652 buffer_free(&stdin_buffer); 653 buffer_free(&stdout_buffer); 654 buffer_free(&stderr_buffer); 655 656 /* Close the file descriptors. */ 657 if (fdout != -1) 658 close(fdout); 659 fdout = -1; 660 fdout_eof = 1; 661 if (fderr != -1) 662 close(fderr); 663 fderr = -1; 664 fderr_eof = 1; 665 if (fdin != -1) 666 close(fdin); 667 fdin = -1; 668 669 channel_free_all(); 670 671 /* We no longer want our SIGCHLD handler to be called. */ 672 mysignal(SIGCHLD, SIG_DFL); 673 674 while ((wait_pid = waitpid(-1, &wait_status, 0)) < 0) 675 if (errno != EINTR) 676 packet_disconnect("wait: %.100s", strerror(errno)); 677 if (wait_pid != pid) 678 error("Strange, wait returned pid %ld, expected %ld", 679 (long)wait_pid, (long)pid); 680 681 /* Check if it exited normally. */ 682 if (WIFEXITED(wait_status)) { 683 /* Yes, normal exit. Get exit status and send it to the client. */ 684 debug("Command exited with status %d.", WEXITSTATUS(wait_status)); 685 packet_start(SSH_SMSG_EXITSTATUS); 686 packet_put_int(WEXITSTATUS(wait_status)); 687 packet_send(); 688 packet_write_wait(); 689 690 /* 691 * Wait for exit confirmation. Note that there might be 692 * other packets coming before it; however, the program has 693 * already died so we just ignore them. The client is 694 * supposed to respond with the confirmation when it receives 695 * the exit status. 696 */ 697 do { 698 type = packet_read(); 699 } 700 while (type != SSH_CMSG_EXIT_CONFIRMATION); 701 702 debug("Received exit confirmation."); 703 return; 704 } 705 /* Check if the program terminated due to a signal. */ 706 if (WIFSIGNALED(wait_status)) 707 packet_disconnect("Command terminated on signal %d.", 708 WTERMSIG(wait_status)); 709 710 /* Some weird exit cause. Just exit. */ 711 packet_disconnect("wait returned status %04x.", wait_status); 712 /* NOTREACHED */ 713 } 714 715 static void 716 collect_children(void) 717 { 718 pid_t pid; 719 sigset_t oset, nset; 720 int status; 721 722 /* block SIGCHLD while we check for dead children */ 723 sigemptyset(&nset); 724 sigaddset(&nset, SIGCHLD); 725 sigprocmask(SIG_BLOCK, &nset, &oset); 726 if (child_terminated) { 727 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 728 (pid < 0 && errno == EINTR)) 729 if (pid > 0) 730 session_close_by_pid(pid, status); 731 child_terminated = 0; 732 } 733 sigprocmask(SIG_SETMASK, &oset, NULL); 734 } 735 736 void 737 server_loop2(Authctxt *authctxt) 738 { 739 fd_set *readset = NULL, *writeset = NULL; 740 int rekeying = 0, max_fd, nalloc = 0; 741 742 debug("Entering interactive session for SSH2."); 743 744 mysignal(SIGCHLD, sigchld_handler); 745 child_terminated = 0; 746 connection_in = packet_get_connection_in(); 747 connection_out = packet_get_connection_out(); 748 749 notify_setup(); 750 751 max_fd = MAX(connection_in, connection_out); 752 max_fd = MAX(max_fd, notify_pipe[0]); 753 754 xxx_authctxt = authctxt; 755 756 server_init_dispatch(); 757 758 for (;;) { 759 process_buffered_input_packets(); 760 761 rekeying = (xxx_kex != NULL && !xxx_kex->done); 762 763 if (!rekeying && packet_not_very_much_data_to_write()) 764 channel_output_poll(); 765 wait_until_can_do_something(&readset, &writeset, &max_fd, 766 &nalloc, 0); 767 768 collect_children(); 769 if (!rekeying) 770 channel_after_select(readset, writeset); 771 process_input(readset); 772 if (connection_closed) 773 break; 774 process_output(writeset); 775 } 776 collect_children(); 777 778 if (readset) 779 xfree(readset); 780 if (writeset) 781 xfree(writeset); 782 783 /* free all channels, no more reads and writes */ 784 channel_free_all(); 785 786 /* free remaining sessions, e.g. remove wtmp entries */ 787 session_destroy_all(NULL); 788 } 789 790 static void 791 server_input_channel_failure(int type, u_int32_t seq, void *ctxt) 792 { 793 debug("Got CHANNEL_FAILURE for keepalive"); 794 /* 795 * reset timeout, since we got a sane answer from the client. 796 * even if this was generated by something other than 797 * the bogus CHANNEL_REQUEST we send for keepalives. 798 */ 799 client_alive_timeouts = 0; 800 } 801 802 803 static void 804 server_input_stdin_data(int type, u_int32_t seq, void *ctxt) 805 { 806 char *data; 807 u_int data_len; 808 809 /* Stdin data from the client. Append it to the buffer. */ 810 /* Ignore any data if the client has closed stdin. */ 811 if (fdin == -1) 812 return; 813 data = packet_get_string(&data_len); 814 packet_check_eom(); 815 buffer_append(&stdin_buffer, data, data_len); 816 memset(data, 0, data_len); 817 xfree(data); 818 } 819 820 static void 821 server_input_eof(int type, u_int32_t seq, void *ctxt) 822 { 823 /* 824 * Eof from the client. The stdin descriptor to the 825 * program will be closed when all buffered data has 826 * drained. 827 */ 828 debug("EOF received for stdin."); 829 packet_check_eom(); 830 stdin_eof = 1; 831 } 832 833 static void 834 server_input_window_size(int type, u_int32_t seq, void *ctxt) 835 { 836 int row = packet_get_int(); 837 int col = packet_get_int(); 838 int xpixel = packet_get_int(); 839 int ypixel = packet_get_int(); 840 841 debug("Window change received."); 842 packet_check_eom(); 843 if (fdin != -1) 844 pty_change_window_size(fdin, row, col, xpixel, ypixel); 845 } 846 847 static Channel * 848 server_request_direct_tcpip(char *ctype) 849 { 850 Channel *c; 851 int sock; 852 char *target, *originator; 853 int target_port, originator_port; 854 855 target = packet_get_string(NULL); 856 target_port = packet_get_int(); 857 originator = packet_get_string(NULL); 858 originator_port = packet_get_int(); 859 packet_check_eom(); 860 861 debug("server_request_direct_tcpip: originator %s port %d, target %s port %d", 862 originator, originator_port, target, target_port); 863 864 /* XXX check permission */ 865 sock = channel_connect_to(target, target_port); 866 xfree(target); 867 xfree(originator); 868 if (sock < 0) 869 return NULL; 870 c = channel_new(ctype, SSH_CHANNEL_CONNECTING, 871 sock, sock, -1, CHAN_TCP_WINDOW_DEFAULT, 872 CHAN_TCP_PACKET_DEFAULT, 0, xstrdup("direct-tcpip"), 1); 873 return c; 874 } 875 876 static Channel * 877 server_request_session(char *ctype) 878 { 879 Channel *c; 880 881 debug("input_session_request"); 882 packet_check_eom(); 883 /* 884 * A server session has no fd to read or write until a 885 * CHANNEL_REQUEST for a shell is made, so we set the type to 886 * SSH_CHANNEL_LARVAL. Additionally, a callback for handling all 887 * CHANNEL_REQUEST messages is registered. 888 */ 889 c = channel_new(ctype, SSH_CHANNEL_LARVAL, 890 -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT, 891 0, xstrdup("server-session"), 1); 892 if (session_open(xxx_authctxt, c->self) != 1) { 893 debug("session open failed, free channel %d", c->self); 894 channel_free(c); 895 return NULL; 896 } 897 channel_register_cleanup(c->self, session_close_by_channel); 898 return c; 899 } 900 901 static void 902 server_input_channel_open(int type, u_int32_t seq, void *ctxt) 903 { 904 Channel *c = NULL; 905 char *ctype; 906 int rchan; 907 u_int rmaxpack, rwindow, len; 908 909 ctype = packet_get_string(&len); 910 rchan = packet_get_int(); 911 rwindow = packet_get_int(); 912 rmaxpack = packet_get_int(); 913 914 debug("server_input_channel_open: ctype %s rchan %d win %d max %d", 915 ctype, rchan, rwindow, rmaxpack); 916 917 if (strcmp(ctype, "session") == 0) { 918 c = server_request_session(ctype); 919 } else if (strcmp(ctype, "direct-tcpip") == 0) { 920 c = server_request_direct_tcpip(ctype); 921 } 922 if (c != NULL) { 923 debug("server_input_channel_open: confirm %s", ctype); 924 c->remote_id = rchan; 925 c->remote_window = rwindow; 926 c->remote_maxpacket = rmaxpack; 927 if (c->type != SSH_CHANNEL_CONNECTING) { 928 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION); 929 packet_put_int(c->remote_id); 930 packet_put_int(c->self); 931 packet_put_int(c->local_window); 932 packet_put_int(c->local_maxpacket); 933 packet_send(); 934 } 935 } else { 936 debug("server_input_channel_open: failure %s", ctype); 937 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE); 938 packet_put_int(rchan); 939 packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED); 940 if (!(datafellows & SSH_BUG_OPENFAILURE)) { 941 packet_put_cstring("open failed"); 942 packet_put_cstring(""); 943 } 944 packet_send(); 945 } 946 xfree(ctype); 947 } 948 949 static void 950 server_input_global_request(int type, u_int32_t seq, void *ctxt) 951 { 952 char *rtype; 953 int want_reply; 954 int success = 0; 955 956 rtype = packet_get_string(NULL); 957 want_reply = packet_get_char(); 958 debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply); 959 960 /* -R style forwarding */ 961 if (strcmp(rtype, "tcpip-forward") == 0) { 962 struct passwd *pw; 963 char *listen_address; 964 u_short listen_port; 965 966 pw = auth_get_user(); 967 if (pw == NULL) 968 fatal("server_input_global_request: no user"); 969 listen_address = packet_get_string(NULL); /* XXX currently ignored */ 970 listen_port = (u_short)packet_get_int(); 971 debug("server_input_global_request: tcpip-forward listen %s port %d", 972 listen_address, listen_port); 973 974 /* check permissions */ 975 if (!options.allow_tcp_forwarding || 976 no_port_forwarding_flag || 977 (listen_port < IPPORT_RESERVED && pw->pw_uid != 0)) { 978 success = 0; 979 packet_send_debug("Server has disabled port forwarding."); 980 } else { 981 /* Start listening on the port */ 982 success = channel_setup_remote_fwd_listener( 983 listen_address, listen_port, options.gateway_ports); 984 } 985 xfree(listen_address); 986 } 987 if (want_reply) { 988 packet_start(success ? 989 SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE); 990 packet_send(); 991 packet_write_wait(); 992 } 993 xfree(rtype); 994 } 995 static void 996 server_input_channel_req(int type, u_int32_t seq, void *ctxt) 997 { 998 Channel *c; 999 int id, reply, success = 0; 1000 char *rtype; 1001 1002 id = packet_get_int(); 1003 rtype = packet_get_string(NULL); 1004 reply = packet_get_char(); 1005 1006 debug("server_input_channel_req: channel %d request %s reply %d", 1007 id, rtype, reply); 1008 1009 if ((c = channel_lookup(id)) == NULL) 1010 packet_disconnect("server_input_channel_req: " 1011 "unknown channel %d", id); 1012 if (c->type == SSH_CHANNEL_LARVAL || c->type == SSH_CHANNEL_OPEN) 1013 success = session_input_channel_req(c, rtype); 1014 if (reply) { 1015 packet_start(success ? 1016 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE); 1017 packet_put_int(c->remote_id); 1018 packet_send(); 1019 } 1020 xfree(rtype); 1021 } 1022 1023 static void 1024 server_init_dispatch_20(void) 1025 { 1026 debug("server_init_dispatch_20"); 1027 dispatch_init(&dispatch_protocol_error); 1028 dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); 1029 dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data); 1030 dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); 1031 dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); 1032 dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open); 1033 dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 1034 dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 1035 dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req); 1036 dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); 1037 dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request); 1038 /* client_alive */ 1039 dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_channel_failure); 1040 /* rekeying */ 1041 dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); 1042 } 1043 static void 1044 server_init_dispatch_13(void) 1045 { 1046 debug("server_init_dispatch_13"); 1047 dispatch_init(NULL); 1048 dispatch_set(SSH_CMSG_EOF, &server_input_eof); 1049 dispatch_set(SSH_CMSG_STDIN_DATA, &server_input_stdin_data); 1050 dispatch_set(SSH_CMSG_WINDOW_SIZE, &server_input_window_size); 1051 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close); 1052 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation); 1053 dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data); 1054 dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 1055 dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 1056 dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open); 1057 } 1058 static void 1059 server_init_dispatch_15(void) 1060 { 1061 server_init_dispatch_13(); 1062 debug("server_init_dispatch_15"); 1063 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof); 1064 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_oclose); 1065 } 1066 static void 1067 server_init_dispatch(void) 1068 { 1069 if (compat20) 1070 server_init_dispatch_20(); 1071 else if (compat13) 1072 server_init_dispatch_13(); 1073 else 1074 server_init_dispatch_15(); 1075 } 1076