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 1.98 2002/02/06 14:55:16 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 signal(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 if (tvp!=NULL) 323 debug3("tvp!=NULL kid %d mili %d", (int) child_terminated, 324 max_time_milliseconds); 325 326 /* Wait for something to happen, or the timeout to expire. */ 327 ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp); 328 329 if (ret == -1) { 330 memset(*readsetp, 0, *nallocp); 331 memset(*writesetp, 0, *nallocp); 332 if (errno != EINTR) 333 error("select: %.100s", strerror(errno)); 334 } else if (ret == 0 && client_alive_scheduled) 335 client_alive_check(); 336 337 notify_done(*readsetp); 338 } 339 340 /* 341 * Processes input from the client and the program. Input data is stored 342 * in buffers and processed later. 343 */ 344 static void 345 process_input(fd_set * readset) 346 { 347 int len; 348 char buf[16384]; 349 350 /* Read and buffer any input data from the client. */ 351 if (FD_ISSET(connection_in, readset)) { 352 len = read(connection_in, buf, sizeof(buf)); 353 if (len == 0) { 354 verbose("Connection closed by remote host."); 355 connection_closed = 1; 356 if (compat20) 357 return; 358 fatal_cleanup(); 359 } else if (len < 0) { 360 if (errno != EINTR && errno != EAGAIN) { 361 verbose("Read error from remote host: %.100s", strerror(errno)); 362 fatal_cleanup(); 363 } 364 } else { 365 /* Buffer any received data. */ 366 packet_process_incoming(buf, len); 367 } 368 } 369 if (compat20) 370 return; 371 372 /* Read and buffer any available stdout data from the program. */ 373 if (!fdout_eof && FD_ISSET(fdout, readset)) { 374 len = read(fdout, buf, sizeof(buf)); 375 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 376 /* do nothing */ 377 } else if (len <= 0) { 378 fdout_eof = 1; 379 } else { 380 buffer_append(&stdout_buffer, buf, len); 381 fdout_bytes += len; 382 } 383 } 384 /* Read and buffer any available stderr data from the program. */ 385 if (!fderr_eof && FD_ISSET(fderr, readset)) { 386 len = read(fderr, buf, sizeof(buf)); 387 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 388 /* do nothing */ 389 } else if (len <= 0) { 390 fderr_eof = 1; 391 } else { 392 buffer_append(&stderr_buffer, buf, len); 393 } 394 } 395 } 396 397 /* 398 * Sends data from internal buffers to client program stdin. 399 */ 400 static void 401 process_output(fd_set * writeset) 402 { 403 struct termios tio; 404 u_char *data; 405 u_int dlen; 406 int len; 407 408 /* Write buffered data to program stdin. */ 409 if (!compat20 && fdin != -1 && FD_ISSET(fdin, writeset)) { 410 data = buffer_ptr(&stdin_buffer); 411 dlen = buffer_len(&stdin_buffer); 412 len = write(fdin, data, dlen); 413 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 414 /* do nothing */ 415 } else if (len <= 0) { 416 if (fdin != fdout) 417 close(fdin); 418 else 419 shutdown(fdin, SHUT_WR); /* We will no longer send. */ 420 fdin = -1; 421 } else { 422 /* Successful write. */ 423 if (fdin_is_tty && dlen >= 1 && data[0] != '\r' && 424 tcgetattr(fdin, &tio) == 0 && 425 !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) { 426 /* 427 * Simulate echo to reduce the impact of 428 * traffic analysis 429 */ 430 packet_send_ignore(len); 431 packet_send(); 432 } 433 /* Consume the data from the buffer. */ 434 buffer_consume(&stdin_buffer, len); 435 /* Update the count of bytes written to the program. */ 436 stdin_bytes += len; 437 } 438 } 439 /* Send any buffered packet data to the client. */ 440 if (FD_ISSET(connection_out, writeset)) 441 packet_write_poll(); 442 } 443 444 /* 445 * Wait until all buffered output has been sent to the client. 446 * This is used when the program terminates. 447 */ 448 static void 449 drain_output(void) 450 { 451 /* Send any buffered stdout data to the client. */ 452 if (buffer_len(&stdout_buffer) > 0) { 453 packet_start(SSH_SMSG_STDOUT_DATA); 454 packet_put_string(buffer_ptr(&stdout_buffer), 455 buffer_len(&stdout_buffer)); 456 packet_send(); 457 /* Update the count of sent bytes. */ 458 stdout_bytes += buffer_len(&stdout_buffer); 459 } 460 /* Send any buffered stderr data to the client. */ 461 if (buffer_len(&stderr_buffer) > 0) { 462 packet_start(SSH_SMSG_STDERR_DATA); 463 packet_put_string(buffer_ptr(&stderr_buffer), 464 buffer_len(&stderr_buffer)); 465 packet_send(); 466 /* Update the count of sent bytes. */ 467 stderr_bytes += buffer_len(&stderr_buffer); 468 } 469 /* Wait until all buffered data has been written to the client. */ 470 packet_write_wait(); 471 } 472 473 static void 474 process_buffered_input_packets(void) 475 { 476 dispatch_run(DISPATCH_NONBLOCK, NULL, compat20 ? xxx_kex : NULL); 477 } 478 479 /* 480 * Performs the interactive session. This handles data transmission between 481 * the client and the program. Note that the notion of stdin, stdout, and 482 * stderr in this function is sort of reversed: this function writes to 483 * stdin (of the child program), and reads from stdout and stderr (of the 484 * child program). 485 */ 486 void 487 server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg) 488 { 489 fd_set *readset = NULL, *writeset = NULL; 490 int max_fd = 0, nalloc = 0; 491 int wait_status; /* Status returned by wait(). */ 492 pid_t wait_pid; /* pid returned by wait(). */ 493 int waiting_termination = 0; /* Have displayed waiting close message. */ 494 u_int max_time_milliseconds; 495 u_int previous_stdout_buffer_bytes; 496 u_int stdout_buffer_bytes; 497 int type; 498 499 debug("Entering interactive session."); 500 501 /* Initialize the SIGCHLD kludge. */ 502 child_terminated = 0; 503 signal(SIGCHLD, sigchld_handler); 504 505 /* Initialize our global variables. */ 506 fdin = fdin_arg; 507 fdout = fdout_arg; 508 fderr = fderr_arg; 509 510 /* nonblocking IO */ 511 set_nonblock(fdin); 512 set_nonblock(fdout); 513 /* we don't have stderr for interactive terminal sessions, see below */ 514 if (fderr != -1) 515 set_nonblock(fderr); 516 517 if (!(datafellows & SSH_BUG_IGNOREMSG) && isatty(fdin)) 518 fdin_is_tty = 1; 519 520 connection_in = packet_get_connection_in(); 521 connection_out = packet_get_connection_out(); 522 523 notify_setup(); 524 525 previous_stdout_buffer_bytes = 0; 526 527 /* Set approximate I/O buffer size. */ 528 if (packet_is_interactive()) 529 buffer_high = 4096; 530 else 531 buffer_high = 64 * 1024; 532 533 #if 0 534 /* Initialize max_fd to the maximum of the known file descriptors. */ 535 max_fd = MAX(connection_in, connection_out); 536 max_fd = MAX(max_fd, fdin); 537 max_fd = MAX(max_fd, fdout); 538 if (fderr != -1) 539 max_fd = MAX(max_fd, fderr); 540 #endif 541 542 /* Initialize Initialize buffers. */ 543 buffer_init(&stdin_buffer); 544 buffer_init(&stdout_buffer); 545 buffer_init(&stderr_buffer); 546 547 /* 548 * If we have no separate fderr (which is the case when we have a pty 549 * - there we cannot make difference between data sent to stdout and 550 * stderr), indicate that we have seen an EOF from stderr. This way 551 * we don\'t need to check the descriptor everywhere. 552 */ 553 if (fderr == -1) 554 fderr_eof = 1; 555 556 server_init_dispatch(); 557 558 /* Main loop of the server for the interactive session mode. */ 559 for (;;) { 560 561 /* Process buffered packets from the client. */ 562 process_buffered_input_packets(); 563 564 /* 565 * If we have received eof, and there is no more pending 566 * input data, cause a real eof by closing fdin. 567 */ 568 if (stdin_eof && fdin != -1 && buffer_len(&stdin_buffer) == 0) { 569 if (fdin != fdout) 570 close(fdin); 571 else 572 shutdown(fdin, SHUT_WR); /* We will no longer send. */ 573 fdin = -1; 574 } 575 /* Make packets from buffered stderr data to send to the client. */ 576 make_packets_from_stderr_data(); 577 578 /* 579 * Make packets from buffered stdout data to send to the 580 * client. If there is very little to send, this arranges to 581 * not send them now, but to wait a short while to see if we 582 * are getting more data. This is necessary, as some systems 583 * wake up readers from a pty after each separate character. 584 */ 585 max_time_milliseconds = 0; 586 stdout_buffer_bytes = buffer_len(&stdout_buffer); 587 if (stdout_buffer_bytes != 0 && stdout_buffer_bytes < 256 && 588 stdout_buffer_bytes != previous_stdout_buffer_bytes) { 589 /* try again after a while */ 590 max_time_milliseconds = 10; 591 } else { 592 /* Send it now. */ 593 make_packets_from_stdout_data(); 594 } 595 previous_stdout_buffer_bytes = buffer_len(&stdout_buffer); 596 597 /* Send channel data to the client. */ 598 if (packet_not_very_much_data_to_write()) 599 channel_output_poll(); 600 601 /* 602 * Bail out of the loop if the program has closed its output 603 * descriptors, and we have no more data to send to the 604 * client, and there is no pending buffered data. 605 */ 606 if (fdout_eof && fderr_eof && !packet_have_data_to_write() && 607 buffer_len(&stdout_buffer) == 0 && buffer_len(&stderr_buffer) == 0) { 608 if (!channel_still_open()) 609 break; 610 if (!waiting_termination) { 611 const char *s = "Waiting for forwarded connections to terminate...\r\n"; 612 char *cp; 613 waiting_termination = 1; 614 buffer_append(&stderr_buffer, s, strlen(s)); 615 616 /* Display list of open channels. */ 617 cp = channel_open_message(); 618 buffer_append(&stderr_buffer, cp, strlen(cp)); 619 xfree(cp); 620 } 621 } 622 max_fd = MAX(connection_in, connection_out); 623 max_fd = MAX(max_fd, fdin); 624 max_fd = MAX(max_fd, fdout); 625 max_fd = MAX(max_fd, fderr); 626 max_fd = MAX(max_fd, notify_pipe[0]); 627 628 /* Sleep in select() until we can do something. */ 629 wait_until_can_do_something(&readset, &writeset, &max_fd, 630 &nalloc, max_time_milliseconds); 631 632 /* Process any channel events. */ 633 channel_after_select(readset, writeset); 634 635 /* Process input from the client and from program stdout/stderr. */ 636 process_input(readset); 637 638 /* Process output to the client and to program stdin. */ 639 process_output(writeset); 640 } 641 if (readset) 642 xfree(readset); 643 if (writeset) 644 xfree(writeset); 645 646 /* Cleanup and termination code. */ 647 648 /* Wait until all output has been sent to the client. */ 649 drain_output(); 650 651 debug("End of interactive session; stdin %ld, stdout (read %ld, sent %ld), stderr %ld bytes.", 652 stdin_bytes, fdout_bytes, stdout_bytes, stderr_bytes); 653 654 /* Free and clear the buffers. */ 655 buffer_free(&stdin_buffer); 656 buffer_free(&stdout_buffer); 657 buffer_free(&stderr_buffer); 658 659 /* Close the file descriptors. */ 660 if (fdout != -1) 661 close(fdout); 662 fdout = -1; 663 fdout_eof = 1; 664 if (fderr != -1) 665 close(fderr); 666 fderr = -1; 667 fderr_eof = 1; 668 if (fdin != -1) 669 close(fdin); 670 fdin = -1; 671 672 channel_free_all(); 673 674 /* We no longer want our SIGCHLD handler to be called. */ 675 signal(SIGCHLD, SIG_DFL); 676 677 wait_pid = waitpid(-1, &wait_status, 0); 678 if (wait_pid == -1) 679 packet_disconnect("wait: %.100s", strerror(errno)); 680 else if (wait_pid != pid) 681 error("Strange, wait returned pid %d, expected %d", 682 wait_pid, pid); 683 684 /* Check if it exited normally. */ 685 if (WIFEXITED(wait_status)) { 686 /* Yes, normal exit. Get exit status and send it to the client. */ 687 debug("Command exited with status %d.", WEXITSTATUS(wait_status)); 688 packet_start(SSH_SMSG_EXITSTATUS); 689 packet_put_int(WEXITSTATUS(wait_status)); 690 packet_send(); 691 packet_write_wait(); 692 693 /* 694 * Wait for exit confirmation. Note that there might be 695 * other packets coming before it; however, the program has 696 * already died so we just ignore them. The client is 697 * supposed to respond with the confirmation when it receives 698 * the exit status. 699 */ 700 do { 701 type = packet_read(); 702 } 703 while (type != SSH_CMSG_EXIT_CONFIRMATION); 704 705 debug("Received exit confirmation."); 706 return; 707 } 708 /* Check if the program terminated due to a signal. */ 709 if (WIFSIGNALED(wait_status)) 710 packet_disconnect("Command terminated on signal %d.", 711 WTERMSIG(wait_status)); 712 713 /* Some weird exit cause. Just exit. */ 714 packet_disconnect("wait returned status %04x.", wait_status); 715 /* NOTREACHED */ 716 } 717 718 static void 719 collect_children(void) 720 { 721 pid_t pid; 722 sigset_t oset, nset; 723 int status; 724 725 /* block SIGCHLD while we check for dead children */ 726 sigemptyset(&nset); 727 sigaddset(&nset, SIGCHLD); 728 sigprocmask(SIG_BLOCK, &nset, &oset); 729 if (child_terminated) { 730 while ((pid = waitpid(-1, &status, WNOHANG)) > 0) 731 session_close_by_pid(pid, status); 732 child_terminated = 0; 733 } 734 sigprocmask(SIG_SETMASK, &oset, NULL); 735 } 736 737 void 738 server_loop2(Authctxt *authctxt) 739 { 740 fd_set *readset = NULL, *writeset = NULL; 741 int rekeying = 0, max_fd, nalloc = 0; 742 743 debug("Entering interactive session for SSH2."); 744 745 signal(SIGCHLD, sigchld_handler); 746 child_terminated = 0; 747 connection_in = packet_get_connection_in(); 748 connection_out = packet_get_connection_out(); 749 750 notify_setup(); 751 752 max_fd = MAX(connection_in, connection_out); 753 max_fd = MAX(max_fd, notify_pipe[0]); 754 755 xxx_authctxt = authctxt; 756 757 server_init_dispatch(); 758 759 for (;;) { 760 process_buffered_input_packets(); 761 762 rekeying = (xxx_kex != NULL && !xxx_kex->done); 763 764 if (!rekeying && packet_not_very_much_data_to_write()) 765 channel_output_poll(); 766 wait_until_can_do_something(&readset, &writeset, &max_fd, 767 &nalloc, 0); 768 769 collect_children(); 770 if (!rekeying) 771 channel_after_select(readset, writeset); 772 process_input(readset); 773 if (connection_closed) 774 break; 775 process_output(writeset); 776 } 777 collect_children(); 778 779 if (readset) 780 xfree(readset); 781 if (writeset) 782 xfree(writeset); 783 784 /* free all channels, no more reads and writes */ 785 channel_free_all(); 786 787 /* free remaining sessions, e.g. remove wtmp entries */ 788 session_destroy_all(); 789 } 790 791 static void 792 server_input_channel_failure(int type, u_int32_t seq, void *ctxt) 793 { 794 debug("Got CHANNEL_FAILURE for keepalive"); 795 /* 796 * reset timeout, since we got a sane answer from the client. 797 * even if this was generated by something other than 798 * the bogus CHANNEL_REQUEST we send for keepalives. 799 */ 800 client_alive_timeouts = 0; 801 } 802 803 804 static void 805 server_input_stdin_data(int type, u_int32_t seq, void *ctxt) 806 { 807 char *data; 808 u_int data_len; 809 810 /* Stdin data from the client. Append it to the buffer. */ 811 /* Ignore any data if the client has closed stdin. */ 812 if (fdin == -1) 813 return; 814 data = packet_get_string(&data_len); 815 packet_check_eom(); 816 buffer_append(&stdin_buffer, data, data_len); 817 memset(data, 0, data_len); 818 xfree(data); 819 } 820 821 static void 822 server_input_eof(int type, u_int32_t seq, void *ctxt) 823 { 824 /* 825 * Eof from the client. The stdin descriptor to the 826 * program will be closed when all buffered data has 827 * drained. 828 */ 829 debug("EOF received for stdin."); 830 packet_check_eom(); 831 stdin_eof = 1; 832 } 833 834 static void 835 server_input_window_size(int type, u_int32_t seq, void *ctxt) 836 { 837 int row = packet_get_int(); 838 int col = packet_get_int(); 839 int xpixel = packet_get_int(); 840 int ypixel = packet_get_int(); 841 842 debug("Window change received."); 843 packet_check_eom(); 844 if (fdin != -1) 845 pty_change_window_size(fdin, row, col, xpixel, ypixel); 846 } 847 848 static Channel * 849 server_request_direct_tcpip(char *ctype) 850 { 851 Channel *c; 852 int sock; 853 char *target, *originator; 854 int target_port, originator_port; 855 856 target = packet_get_string(NULL); 857 target_port = packet_get_int(); 858 originator = packet_get_string(NULL); 859 originator_port = packet_get_int(); 860 packet_check_eom(); 861 862 debug("server_request_direct_tcpip: originator %s port %d, target %s port %d", 863 originator, originator_port, target, target_port); 864 865 /* XXX check permission */ 866 sock = channel_connect_to(target, target_port); 867 xfree(target); 868 xfree(originator); 869 if (sock < 0) 870 return NULL; 871 c = channel_new(ctype, SSH_CHANNEL_CONNECTING, 872 sock, sock, -1, CHAN_TCP_WINDOW_DEFAULT, 873 CHAN_TCP_PACKET_DEFAULT, 0, xstrdup("direct-tcpip"), 1); 874 return c; 875 } 876 877 static Channel * 878 server_request_session(char *ctype) 879 { 880 Channel *c; 881 882 debug("input_session_request"); 883 packet_check_eom(); 884 /* 885 * A server session has no fd to read or write until a 886 * CHANNEL_REQUEST for a shell is made, so we set the type to 887 * SSH_CHANNEL_LARVAL. Additionally, a callback for handling all 888 * CHANNEL_REQUEST messages is registered. 889 */ 890 c = channel_new(ctype, SSH_CHANNEL_LARVAL, 891 -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT, 892 0, xstrdup("server-session"), 1); 893 if (session_open(xxx_authctxt, c->self) != 1) { 894 debug("session open failed, free channel %d", c->self); 895 channel_free(c); 896 return NULL; 897 } 898 channel_register_cleanup(c->self, session_close_by_channel); 899 return c; 900 } 901 902 static void 903 server_input_channel_open(int type, u_int32_t seq, void *ctxt) 904 { 905 Channel *c = NULL; 906 char *ctype; 907 u_int len; 908 int rchan; 909 int rmaxpack; 910 int rwindow; 911 912 ctype = packet_get_string(&len); 913 rchan = packet_get_int(); 914 rwindow = packet_get_int(); 915 rmaxpack = packet_get_int(); 916 917 debug("server_input_channel_open: ctype %s rchan %d win %d max %d", 918 ctype, rchan, rwindow, rmaxpack); 919 920 if (strcmp(ctype, "session") == 0) { 921 c = server_request_session(ctype); 922 } else if (strcmp(ctype, "direct-tcpip") == 0) { 923 c = server_request_direct_tcpip(ctype); 924 } 925 if (c != NULL) { 926 debug("server_input_channel_open: confirm %s", ctype); 927 c->remote_id = rchan; 928 c->remote_window = rwindow; 929 c->remote_maxpacket = rmaxpack; 930 if (c->type != SSH_CHANNEL_CONNECTING) { 931 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION); 932 packet_put_int(c->remote_id); 933 packet_put_int(c->self); 934 packet_put_int(c->local_window); 935 packet_put_int(c->local_maxpacket); 936 packet_send(); 937 } 938 } else { 939 debug("server_input_channel_open: failure %s", ctype); 940 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE); 941 packet_put_int(rchan); 942 packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED); 943 if (!(datafellows & SSH_BUG_OPENFAILURE)) { 944 packet_put_cstring("open failed"); 945 packet_put_cstring(""); 946 } 947 packet_send(); 948 } 949 xfree(ctype); 950 } 951 952 static void 953 server_input_global_request(int type, u_int32_t seq, void *ctxt) 954 { 955 char *rtype; 956 int want_reply; 957 int success = 0; 958 959 rtype = packet_get_string(NULL); 960 want_reply = packet_get_char(); 961 debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply); 962 963 /* -R style forwarding */ 964 if (strcmp(rtype, "tcpip-forward") == 0) { 965 struct passwd *pw; 966 char *listen_address; 967 u_short listen_port; 968 969 pw = auth_get_user(); 970 if (pw == NULL) 971 fatal("server_input_global_request: no user"); 972 listen_address = packet_get_string(NULL); /* XXX currently ignored */ 973 listen_port = (u_short)packet_get_int(); 974 debug("server_input_global_request: tcpip-forward listen %s port %d", 975 listen_address, listen_port); 976 977 /* check permissions */ 978 if (!options.allow_tcp_forwarding || 979 no_port_forwarding_flag || 980 (listen_port < IPPORT_RESERVED && pw->pw_uid != 0)) { 981 success = 0; 982 packet_send_debug("Server has disabled port forwarding."); 983 } else { 984 /* Start listening on the port */ 985 success = channel_setup_remote_fwd_listener( 986 listen_address, listen_port, options.gateway_ports); 987 } 988 xfree(listen_address); 989 } 990 if (want_reply) { 991 packet_start(success ? 992 SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE); 993 packet_send(); 994 packet_write_wait(); 995 } 996 xfree(rtype); 997 } 998 static void 999 server_input_channel_req(int type, u_int32_t seq, void *ctxt) 1000 { 1001 Channel *c; 1002 int id, reply, success = 0; 1003 char *rtype; 1004 1005 id = packet_get_int(); 1006 rtype = packet_get_string(NULL); 1007 reply = packet_get_char(); 1008 1009 debug("server_input_channel_req: channel %d request %s reply %d", 1010 id, rtype, reply); 1011 1012 if ((c = channel_lookup(id)) == NULL) 1013 packet_disconnect("server_input_channel_req: " 1014 "unknown channel %d", id); 1015 if (c->type == SSH_CHANNEL_LARVAL || c->type == SSH_CHANNEL_OPEN) 1016 success = session_input_channel_req(c, rtype); 1017 if (reply) { 1018 packet_start(success ? 1019 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE); 1020 packet_put_int(c->remote_id); 1021 packet_send(); 1022 } 1023 xfree(rtype); 1024 } 1025 1026 static void 1027 server_init_dispatch_20(void) 1028 { 1029 debug("server_init_dispatch_20"); 1030 dispatch_init(&dispatch_protocol_error); 1031 dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); 1032 dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data); 1033 dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); 1034 dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); 1035 dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open); 1036 dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 1037 dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 1038 dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req); 1039 dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); 1040 dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request); 1041 /* client_alive */ 1042 dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_channel_failure); 1043 /* rekeying */ 1044 dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); 1045 } 1046 static void 1047 server_init_dispatch_13(void) 1048 { 1049 debug("server_init_dispatch_13"); 1050 dispatch_init(NULL); 1051 dispatch_set(SSH_CMSG_EOF, &server_input_eof); 1052 dispatch_set(SSH_CMSG_STDIN_DATA, &server_input_stdin_data); 1053 dispatch_set(SSH_CMSG_WINDOW_SIZE, &server_input_window_size); 1054 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close); 1055 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation); 1056 dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data); 1057 dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 1058 dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 1059 dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open); 1060 } 1061 static void 1062 server_init_dispatch_15(void) 1063 { 1064 server_init_dispatch_13(); 1065 debug("server_init_dispatch_15"); 1066 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof); 1067 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_oclose); 1068 } 1069 static void 1070 server_init_dispatch(void) 1071 { 1072 if (compat20) 1073 server_init_dispatch_20(); 1074 else if (compat13) 1075 server_init_dispatch_13(); 1076 else 1077 server_init_dispatch_15(); 1078 } 1079