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 1.110 2003/06/24 08:23:46 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 "canohost.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 #ifndef _UNICOS 148 mysignal(SIGCHLD, sigchld_handler); 149 #endif 150 notify_parent(); 151 errno = save_errno; 152 } 153 154 /* 155 * Make packets from buffered stderr data, and buffer it for sending 156 * to the client. 157 */ 158 static void 159 make_packets_from_stderr_data(void) 160 { 161 u_int len; 162 163 /* Send buffered stderr data to the client. */ 164 while (buffer_len(&stderr_buffer) > 0 && 165 packet_not_very_much_data_to_write()) { 166 len = buffer_len(&stderr_buffer); 167 if (packet_is_interactive()) { 168 if (len > 512) 169 len = 512; 170 } else { 171 /* Keep the packets at reasonable size. */ 172 if (len > packet_get_maxsize()) 173 len = packet_get_maxsize(); 174 } 175 packet_start(SSH_SMSG_STDERR_DATA); 176 packet_put_string(buffer_ptr(&stderr_buffer), len); 177 packet_send(); 178 buffer_consume(&stderr_buffer, len); 179 stderr_bytes += len; 180 } 181 } 182 183 /* 184 * Make packets from buffered stdout data, and buffer it for sending to the 185 * client. 186 */ 187 static void 188 make_packets_from_stdout_data(void) 189 { 190 u_int len; 191 192 /* Send buffered stdout data to the client. */ 193 while (buffer_len(&stdout_buffer) > 0 && 194 packet_not_very_much_data_to_write()) { 195 len = buffer_len(&stdout_buffer); 196 if (packet_is_interactive()) { 197 if (len > 512) 198 len = 512; 199 } else { 200 /* Keep the packets at reasonable size. */ 201 if (len > packet_get_maxsize()) 202 len = packet_get_maxsize(); 203 } 204 packet_start(SSH_SMSG_STDOUT_DATA); 205 packet_put_string(buffer_ptr(&stdout_buffer), len); 206 packet_send(); 207 buffer_consume(&stdout_buffer, len); 208 stdout_bytes += len; 209 } 210 } 211 212 static void 213 client_alive_check(void) 214 { 215 static int had_channel = 0; 216 int id; 217 218 id = channel_find_open(); 219 if (id == -1) { 220 if (!had_channel) 221 return; 222 packet_disconnect("No open channels after timeout!"); 223 } 224 had_channel = 1; 225 226 /* timeout, check to see how many we have had */ 227 if (++client_alive_timeouts > options.client_alive_count_max) 228 packet_disconnect("Timeout, your session not responding."); 229 230 /* 231 * send a bogus channel request with "wantreply", 232 * we should get back a failure 233 */ 234 channel_request_start(id, "keepalive@openssh.com", 1); 235 packet_send(); 236 } 237 238 /* 239 * Sleep in select() until we can do something. This will initialize the 240 * select masks. Upon return, the masks will indicate which descriptors 241 * have data or can accept data. Optionally, a maximum time can be specified 242 * for the duration of the wait (0 = infinite). 243 */ 244 static void 245 wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp, 246 int *nallocp, u_int max_time_milliseconds) 247 { 248 struct timeval tv, *tvp; 249 int ret; 250 int client_alive_scheduled = 0; 251 252 /* 253 * if using client_alive, set the max timeout accordingly, 254 * and indicate that this particular timeout was for client 255 * alive by setting the client_alive_scheduled flag. 256 * 257 * this could be randomized somewhat to make traffic 258 * analysis more difficult, but we're not doing it yet. 259 */ 260 if (compat20 && 261 max_time_milliseconds == 0 && options.client_alive_interval) { 262 client_alive_scheduled = 1; 263 max_time_milliseconds = options.client_alive_interval * 1000; 264 } 265 266 /* Allocate and update select() masks for channel descriptors. */ 267 channel_prepare_select(readsetp, writesetp, maxfdp, nallocp, 0); 268 269 if (compat20) { 270 #if 0 271 /* wrong: bad condition XXX */ 272 if (channel_not_very_much_buffered_data()) 273 #endif 274 FD_SET(connection_in, *readsetp); 275 } else { 276 /* 277 * Read packets from the client unless we have too much 278 * buffered stdin or channel data. 279 */ 280 if (buffer_len(&stdin_buffer) < buffer_high && 281 channel_not_very_much_buffered_data()) 282 FD_SET(connection_in, *readsetp); 283 /* 284 * If there is not too much data already buffered going to 285 * the client, try to get some more data from the program. 286 */ 287 if (packet_not_very_much_data_to_write()) { 288 if (!fdout_eof) 289 FD_SET(fdout, *readsetp); 290 if (!fderr_eof) 291 FD_SET(fderr, *readsetp); 292 } 293 /* 294 * If we have buffered data, try to write some of that data 295 * to the program. 296 */ 297 if (fdin != -1 && buffer_len(&stdin_buffer) > 0) 298 FD_SET(fdin, *writesetp); 299 } 300 notify_prepare(*readsetp); 301 302 /* 303 * If we have buffered packet data going to the client, mark that 304 * descriptor. 305 */ 306 if (packet_have_data_to_write()) 307 FD_SET(connection_out, *writesetp); 308 309 /* 310 * If child has terminated and there is enough buffer space to read 311 * from it, then read as much as is available and exit. 312 */ 313 if (child_terminated && packet_not_very_much_data_to_write()) 314 if (max_time_milliseconds == 0 || client_alive_scheduled) 315 max_time_milliseconds = 100; 316 317 if (max_time_milliseconds == 0) 318 tvp = NULL; 319 else { 320 tv.tv_sec = max_time_milliseconds / 1000; 321 tv.tv_usec = 1000 * (max_time_milliseconds % 1000); 322 tvp = &tv; 323 } 324 325 /* Wait for something to happen, or the timeout to expire. */ 326 ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp); 327 328 if (ret == -1) { 329 memset(*readsetp, 0, *nallocp); 330 memset(*writesetp, 0, *nallocp); 331 if (errno != EINTR) 332 error("select: %.100s", strerror(errno)); 333 } else if (ret == 0 && client_alive_scheduled) 334 client_alive_check(); 335 336 notify_done(*readsetp); 337 } 338 339 /* 340 * Processes input from the client and the program. Input data is stored 341 * in buffers and processed later. 342 */ 343 static void 344 process_input(fd_set * readset) 345 { 346 int len; 347 char buf[16384]; 348 349 /* Read and buffer any input data from the client. */ 350 if (FD_ISSET(connection_in, readset)) { 351 len = read(connection_in, buf, sizeof(buf)); 352 if (len == 0) { 353 verbose("Connection closed by %.100s", 354 get_remote_ipaddr()); 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 " 362 "%.100s: %.100s", 363 get_remote_ipaddr(), strerror(errno)); 364 fatal_cleanup(); 365 } 366 } else { 367 /* Buffer any received data. */ 368 packet_process_incoming(buf, len); 369 } 370 } 371 if (compat20) 372 return; 373 374 /* Read and buffer any available stdout data from the program. */ 375 if (!fdout_eof && FD_ISSET(fdout, readset)) { 376 len = read(fdout, buf, sizeof(buf)); 377 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 378 /* do nothing */ 379 } else if (len <= 0) { 380 fdout_eof = 1; 381 } else { 382 buffer_append(&stdout_buffer, buf, len); 383 fdout_bytes += len; 384 } 385 } 386 /* Read and buffer any available stderr data from the program. */ 387 if (!fderr_eof && FD_ISSET(fderr, readset)) { 388 len = read(fderr, buf, sizeof(buf)); 389 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 390 /* do nothing */ 391 } else if (len <= 0) { 392 fderr_eof = 1; 393 } else { 394 buffer_append(&stderr_buffer, buf, len); 395 } 396 } 397 } 398 399 /* 400 * Sends data from internal buffers to client program stdin. 401 */ 402 static void 403 process_output(fd_set * writeset) 404 { 405 struct termios tio; 406 u_char *data; 407 u_int dlen; 408 int len; 409 410 /* Write buffered data to program stdin. */ 411 if (!compat20 && fdin != -1 && FD_ISSET(fdin, writeset)) { 412 data = buffer_ptr(&stdin_buffer); 413 dlen = buffer_len(&stdin_buffer); 414 len = write(fdin, data, dlen); 415 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 416 /* do nothing */ 417 } else if (len <= 0) { 418 if (fdin != fdout) 419 close(fdin); 420 else 421 shutdown(fdin, SHUT_WR); /* We will no longer send. */ 422 fdin = -1; 423 } else { 424 /* Successful write. */ 425 if (fdin_is_tty && dlen >= 1 && data[0] != '\r' && 426 tcgetattr(fdin, &tio) == 0 && 427 !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) { 428 /* 429 * Simulate echo to reduce the impact of 430 * traffic analysis 431 */ 432 packet_send_ignore(len); 433 packet_send(); 434 } 435 /* Consume the data from the buffer. */ 436 buffer_consume(&stdin_buffer, len); 437 /* Update the count of bytes written to the program. */ 438 stdin_bytes += len; 439 } 440 } 441 /* Send any buffered packet data to the client. */ 442 if (FD_ISSET(connection_out, writeset)) 443 packet_write_poll(); 444 } 445 446 /* 447 * Wait until all buffered output has been sent to the client. 448 * This is used when the program terminates. 449 */ 450 static void 451 drain_output(void) 452 { 453 /* Send any buffered stdout data to the client. */ 454 if (buffer_len(&stdout_buffer) > 0) { 455 packet_start(SSH_SMSG_STDOUT_DATA); 456 packet_put_string(buffer_ptr(&stdout_buffer), 457 buffer_len(&stdout_buffer)); 458 packet_send(); 459 /* Update the count of sent bytes. */ 460 stdout_bytes += buffer_len(&stdout_buffer); 461 } 462 /* Send any buffered stderr data to the client. */ 463 if (buffer_len(&stderr_buffer) > 0) { 464 packet_start(SSH_SMSG_STDERR_DATA); 465 packet_put_string(buffer_ptr(&stderr_buffer), 466 buffer_len(&stderr_buffer)); 467 packet_send(); 468 /* Update the count of sent bytes. */ 469 stderr_bytes += buffer_len(&stderr_buffer); 470 } 471 /* Wait until all buffered data has been written to the client. */ 472 packet_write_wait(); 473 } 474 475 static void 476 process_buffered_input_packets(void) 477 { 478 dispatch_run(DISPATCH_NONBLOCK, NULL, compat20 ? xxx_kex : NULL); 479 } 480 481 /* 482 * Performs the interactive session. This handles data transmission between 483 * the client and the program. Note that the notion of stdin, stdout, and 484 * stderr in this function is sort of reversed: this function writes to 485 * stdin (of the child program), and reads from stdout and stderr (of the 486 * child program). 487 */ 488 void 489 server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg) 490 { 491 fd_set *readset = NULL, *writeset = NULL; 492 int max_fd = 0, nalloc = 0; 493 int wait_status; /* Status returned by wait(). */ 494 pid_t wait_pid; /* pid returned by wait(). */ 495 int waiting_termination = 0; /* Have displayed waiting close message. */ 496 u_int max_time_milliseconds; 497 u_int previous_stdout_buffer_bytes; 498 u_int stdout_buffer_bytes; 499 int type; 500 501 debug("Entering interactive session."); 502 503 /* Initialize the SIGCHLD kludge. */ 504 child_terminated = 0; 505 mysignal(SIGCHLD, sigchld_handler); 506 507 /* Initialize our global variables. */ 508 fdin = fdin_arg; 509 fdout = fdout_arg; 510 fderr = fderr_arg; 511 512 /* nonblocking IO */ 513 set_nonblock(fdin); 514 set_nonblock(fdout); 515 /* we don't have stderr for interactive terminal sessions, see below */ 516 if (fderr != -1) 517 set_nonblock(fderr); 518 519 if (!(datafellows & SSH_BUG_IGNOREMSG) && isatty(fdin)) 520 fdin_is_tty = 1; 521 522 connection_in = packet_get_connection_in(); 523 connection_out = packet_get_connection_out(); 524 525 notify_setup(); 526 527 previous_stdout_buffer_bytes = 0; 528 529 /* Set approximate I/O buffer size. */ 530 if (packet_is_interactive()) 531 buffer_high = 4096; 532 else 533 buffer_high = 64 * 1024; 534 535 #if 0 536 /* Initialize max_fd to the maximum of the known file descriptors. */ 537 max_fd = MAX(connection_in, connection_out); 538 max_fd = MAX(max_fd, fdin); 539 max_fd = MAX(max_fd, fdout); 540 if (fderr != -1) 541 max_fd = MAX(max_fd, fderr); 542 #endif 543 544 /* Initialize Initialize buffers. */ 545 buffer_init(&stdin_buffer); 546 buffer_init(&stdout_buffer); 547 buffer_init(&stderr_buffer); 548 549 /* 550 * If we have no separate fderr (which is the case when we have a pty 551 * - there we cannot make difference between data sent to stdout and 552 * stderr), indicate that we have seen an EOF from stderr. This way 553 * we don\'t need to check the descriptor everywhere. 554 */ 555 if (fderr == -1) 556 fderr_eof = 1; 557 558 server_init_dispatch(); 559 560 /* Main loop of the server for the interactive session mode. */ 561 for (;;) { 562 563 /* Process buffered packets from the client. */ 564 process_buffered_input_packets(); 565 566 /* 567 * If we have received eof, and there is no more pending 568 * input data, cause a real eof by closing fdin. 569 */ 570 if (stdin_eof && fdin != -1 && buffer_len(&stdin_buffer) == 0) { 571 if (fdin != fdout) 572 close(fdin); 573 else 574 shutdown(fdin, SHUT_WR); /* We will no longer send. */ 575 fdin = -1; 576 } 577 /* Make packets from buffered stderr data to send to the client. */ 578 make_packets_from_stderr_data(); 579 580 /* 581 * Make packets from buffered stdout data to send to the 582 * client. If there is very little to send, this arranges to 583 * not send them now, but to wait a short while to see if we 584 * are getting more data. This is necessary, as some systems 585 * wake up readers from a pty after each separate character. 586 */ 587 max_time_milliseconds = 0; 588 stdout_buffer_bytes = buffer_len(&stdout_buffer); 589 if (stdout_buffer_bytes != 0 && stdout_buffer_bytes < 256 && 590 stdout_buffer_bytes != previous_stdout_buffer_bytes) { 591 /* try again after a while */ 592 max_time_milliseconds = 10; 593 } else { 594 /* Send it now. */ 595 make_packets_from_stdout_data(); 596 } 597 previous_stdout_buffer_bytes = buffer_len(&stdout_buffer); 598 599 /* Send channel data to the client. */ 600 if (packet_not_very_much_data_to_write()) 601 channel_output_poll(); 602 603 /* 604 * Bail out of the loop if the program has closed its output 605 * descriptors, and we have no more data to send to the 606 * client, and there is no pending buffered data. 607 */ 608 if (fdout_eof && fderr_eof && !packet_have_data_to_write() && 609 buffer_len(&stdout_buffer) == 0 && buffer_len(&stderr_buffer) == 0) { 610 if (!channel_still_open()) 611 break; 612 if (!waiting_termination) { 613 const char *s = "Waiting for forwarded connections to terminate...\r\n"; 614 char *cp; 615 waiting_termination = 1; 616 buffer_append(&stderr_buffer, s, strlen(s)); 617 618 /* Display list of open channels. */ 619 cp = channel_open_message(); 620 buffer_append(&stderr_buffer, cp, strlen(cp)); 621 xfree(cp); 622 } 623 } 624 max_fd = MAX(connection_in, connection_out); 625 max_fd = MAX(max_fd, fdin); 626 max_fd = MAX(max_fd, fdout); 627 max_fd = MAX(max_fd, fderr); 628 max_fd = MAX(max_fd, notify_pipe[0]); 629 630 /* Sleep in select() until we can do something. */ 631 wait_until_can_do_something(&readset, &writeset, &max_fd, 632 &nalloc, max_time_milliseconds); 633 634 /* Process any channel events. */ 635 channel_after_select(readset, writeset); 636 637 /* Process input from the client and from program stdout/stderr. */ 638 process_input(readset); 639 640 /* Process output to the client and to program stdin. */ 641 process_output(writeset); 642 } 643 if (readset) 644 xfree(readset); 645 if (writeset) 646 xfree(writeset); 647 648 /* Cleanup and termination code. */ 649 650 /* Wait until all output has been sent to the client. */ 651 drain_output(); 652 653 debug("End of interactive session; stdin %ld, stdout (read %ld, sent %ld), stderr %ld bytes.", 654 stdin_bytes, fdout_bytes, stdout_bytes, stderr_bytes); 655 656 /* Free and clear the buffers. */ 657 buffer_free(&stdin_buffer); 658 buffer_free(&stdout_buffer); 659 buffer_free(&stderr_buffer); 660 661 /* Close the file descriptors. */ 662 if (fdout != -1) 663 close(fdout); 664 fdout = -1; 665 fdout_eof = 1; 666 if (fderr != -1) 667 close(fderr); 668 fderr = -1; 669 fderr_eof = 1; 670 if (fdin != -1) 671 close(fdin); 672 fdin = -1; 673 674 channel_free_all(); 675 676 /* We no longer want our SIGCHLD handler to be called. */ 677 mysignal(SIGCHLD, SIG_DFL); 678 679 while ((wait_pid = waitpid(-1, &wait_status, 0)) < 0) 680 if (errno != EINTR) 681 packet_disconnect("wait: %.100s", strerror(errno)); 682 if (wait_pid != pid) 683 error("Strange, wait returned pid %ld, expected %ld", 684 (long)wait_pid, (long)pid); 685 686 /* Check if it exited normally. */ 687 if (WIFEXITED(wait_status)) { 688 /* Yes, normal exit. Get exit status and send it to the client. */ 689 debug("Command exited with status %d.", WEXITSTATUS(wait_status)); 690 packet_start(SSH_SMSG_EXITSTATUS); 691 packet_put_int(WEXITSTATUS(wait_status)); 692 packet_send(); 693 packet_write_wait(); 694 695 /* 696 * Wait for exit confirmation. Note that there might be 697 * other packets coming before it; however, the program has 698 * already died so we just ignore them. The client is 699 * supposed to respond with the confirmation when it receives 700 * the exit status. 701 */ 702 do { 703 type = packet_read(); 704 } 705 while (type != SSH_CMSG_EXIT_CONFIRMATION); 706 707 debug("Received exit confirmation."); 708 return; 709 } 710 /* Check if the program terminated due to a signal. */ 711 if (WIFSIGNALED(wait_status)) 712 packet_disconnect("Command terminated on signal %d.", 713 WTERMSIG(wait_status)); 714 715 /* Some weird exit cause. Just exit. */ 716 packet_disconnect("wait returned status %04x.", wait_status); 717 /* NOTREACHED */ 718 } 719 720 static void 721 collect_children(void) 722 { 723 pid_t pid; 724 sigset_t oset, nset; 725 int status; 726 727 /* block SIGCHLD while we check for dead children */ 728 sigemptyset(&nset); 729 sigaddset(&nset, SIGCHLD); 730 sigprocmask(SIG_BLOCK, &nset, &oset); 731 if (child_terminated) { 732 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 733 (pid < 0 && errno == EINTR)) 734 if (pid > 0) 735 session_close_by_pid(pid, status); 736 child_terminated = 0; 737 } 738 sigprocmask(SIG_SETMASK, &oset, NULL); 739 } 740 741 void 742 server_loop2(Authctxt *authctxt) 743 { 744 fd_set *readset = NULL, *writeset = NULL; 745 int rekeying = 0, max_fd, nalloc = 0; 746 747 debug("Entering interactive session for SSH2."); 748 749 mysignal(SIGCHLD, sigchld_handler); 750 child_terminated = 0; 751 connection_in = packet_get_connection_in(); 752 connection_out = packet_get_connection_out(); 753 754 notify_setup(); 755 756 max_fd = MAX(connection_in, connection_out); 757 max_fd = MAX(max_fd, notify_pipe[0]); 758 759 xxx_authctxt = authctxt; 760 761 server_init_dispatch(); 762 763 for (;;) { 764 process_buffered_input_packets(); 765 766 rekeying = (xxx_kex != NULL && !xxx_kex->done); 767 768 if (!rekeying && packet_not_very_much_data_to_write()) 769 channel_output_poll(); 770 wait_until_can_do_something(&readset, &writeset, &max_fd, 771 &nalloc, 0); 772 773 collect_children(); 774 if (!rekeying) { 775 channel_after_select(readset, writeset); 776 if (packet_need_rekeying()) { 777 debug("need rekeying"); 778 xxx_kex->done = 0; 779 kex_send_kexinit(xxx_kex); 780 } 781 } 782 process_input(readset); 783 if (connection_closed) 784 break; 785 process_output(writeset); 786 } 787 collect_children(); 788 789 if (readset) 790 xfree(readset); 791 if (writeset) 792 xfree(writeset); 793 794 /* free all channels, no more reads and writes */ 795 channel_free_all(); 796 797 /* free remaining sessions, e.g. remove wtmp entries */ 798 session_destroy_all(NULL); 799 } 800 801 static void 802 server_input_channel_failure(int type, u_int32_t seq, void *ctxt) 803 { 804 debug("Got CHANNEL_FAILURE for keepalive"); 805 /* 806 * reset timeout, since we got a sane answer from the client. 807 * even if this was generated by something other than 808 * the bogus CHANNEL_REQUEST we send for keepalives. 809 */ 810 client_alive_timeouts = 0; 811 } 812 813 814 static void 815 server_input_stdin_data(int type, u_int32_t seq, void *ctxt) 816 { 817 char *data; 818 u_int data_len; 819 820 /* Stdin data from the client. Append it to the buffer. */ 821 /* Ignore any data if the client has closed stdin. */ 822 if (fdin == -1) 823 return; 824 data = packet_get_string(&data_len); 825 packet_check_eom(); 826 buffer_append(&stdin_buffer, data, data_len); 827 memset(data, 0, data_len); 828 xfree(data); 829 } 830 831 static void 832 server_input_eof(int type, u_int32_t seq, void *ctxt) 833 { 834 /* 835 * Eof from the client. The stdin descriptor to the 836 * program will be closed when all buffered data has 837 * drained. 838 */ 839 debug("EOF received for stdin."); 840 packet_check_eom(); 841 stdin_eof = 1; 842 } 843 844 static void 845 server_input_window_size(int type, u_int32_t seq, void *ctxt) 846 { 847 int row = packet_get_int(); 848 int col = packet_get_int(); 849 int xpixel = packet_get_int(); 850 int ypixel = packet_get_int(); 851 852 debug("Window change received."); 853 packet_check_eom(); 854 if (fdin != -1) 855 pty_change_window_size(fdin, row, col, xpixel, ypixel); 856 } 857 858 static Channel * 859 server_request_direct_tcpip(char *ctype) 860 { 861 Channel *c; 862 int sock; 863 char *target, *originator; 864 int target_port, originator_port; 865 866 target = packet_get_string(NULL); 867 target_port = packet_get_int(); 868 originator = packet_get_string(NULL); 869 originator_port = packet_get_int(); 870 packet_check_eom(); 871 872 debug("server_request_direct_tcpip: originator %s port %d, target %s port %d", 873 originator, originator_port, target, target_port); 874 875 /* XXX check permission */ 876 sock = channel_connect_to(target, target_port); 877 xfree(target); 878 xfree(originator); 879 if (sock < 0) 880 return NULL; 881 c = channel_new(ctype, SSH_CHANNEL_CONNECTING, 882 sock, sock, -1, CHAN_TCP_WINDOW_DEFAULT, 883 CHAN_TCP_PACKET_DEFAULT, 0, "direct-tcpip", 1); 884 return c; 885 } 886 887 static Channel * 888 server_request_session(char *ctype) 889 { 890 Channel *c; 891 892 debug("input_session_request"); 893 packet_check_eom(); 894 /* 895 * A server session has no fd to read or write until a 896 * CHANNEL_REQUEST for a shell is made, so we set the type to 897 * SSH_CHANNEL_LARVAL. Additionally, a callback for handling all 898 * CHANNEL_REQUEST messages is registered. 899 */ 900 c = channel_new(ctype, SSH_CHANNEL_LARVAL, 901 -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT, 902 0, "server-session", 1); 903 if (session_open(xxx_authctxt, c->self) != 1) { 904 debug("session open failed, free channel %d", c->self); 905 channel_free(c); 906 return NULL; 907 } 908 channel_register_cleanup(c->self, session_close_by_channel); 909 return c; 910 } 911 912 static void 913 server_input_channel_open(int type, u_int32_t seq, void *ctxt) 914 { 915 Channel *c = NULL; 916 char *ctype; 917 int rchan; 918 u_int rmaxpack, rwindow, len; 919 920 ctype = packet_get_string(&len); 921 rchan = packet_get_int(); 922 rwindow = packet_get_int(); 923 rmaxpack = packet_get_int(); 924 925 debug("server_input_channel_open: ctype %s rchan %d win %d max %d", 926 ctype, rchan, rwindow, rmaxpack); 927 928 if (strcmp(ctype, "session") == 0) { 929 c = server_request_session(ctype); 930 } else if (strcmp(ctype, "direct-tcpip") == 0) { 931 c = server_request_direct_tcpip(ctype); 932 } 933 if (c != NULL) { 934 debug("server_input_channel_open: confirm %s", ctype); 935 c->remote_id = rchan; 936 c->remote_window = rwindow; 937 c->remote_maxpacket = rmaxpack; 938 if (c->type != SSH_CHANNEL_CONNECTING) { 939 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION); 940 packet_put_int(c->remote_id); 941 packet_put_int(c->self); 942 packet_put_int(c->local_window); 943 packet_put_int(c->local_maxpacket); 944 packet_send(); 945 } 946 } else { 947 debug("server_input_channel_open: failure %s", ctype); 948 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE); 949 packet_put_int(rchan); 950 packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED); 951 if (!(datafellows & SSH_BUG_OPENFAILURE)) { 952 packet_put_cstring("open failed"); 953 packet_put_cstring(""); 954 } 955 packet_send(); 956 } 957 xfree(ctype); 958 } 959 960 static void 961 server_input_global_request(int type, u_int32_t seq, void *ctxt) 962 { 963 char *rtype; 964 int want_reply; 965 int success = 0; 966 967 rtype = packet_get_string(NULL); 968 want_reply = packet_get_char(); 969 debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply); 970 971 /* -R style forwarding */ 972 if (strcmp(rtype, "tcpip-forward") == 0) { 973 struct passwd *pw; 974 char *listen_address; 975 u_short listen_port; 976 977 pw = auth_get_user(); 978 if (pw == NULL) 979 fatal("server_input_global_request: no user"); 980 listen_address = packet_get_string(NULL); 981 listen_port = (u_short)packet_get_int(); 982 debug("server_input_global_request: tcpip-forward listen %s port %d", 983 listen_address, listen_port); 984 985 /* check permissions */ 986 if (!options.allow_tcp_forwarding || 987 no_port_forwarding_flag 988 #ifndef NO_IPPORT_RESERVED_CONCEPT 989 || (listen_port < IPPORT_RESERVED && pw->pw_uid != 0) 990 #endif 991 ) { 992 success = 0; 993 packet_send_debug("Server has disabled port forwarding."); 994 } else { 995 /* Start listening on the port */ 996 success = channel_setup_remote_fwd_listener( 997 listen_address, listen_port, options.gateway_ports); 998 } 999 xfree(listen_address); 1000 } 1001 if (want_reply) { 1002 packet_start(success ? 1003 SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE); 1004 packet_send(); 1005 packet_write_wait(); 1006 } 1007 xfree(rtype); 1008 } 1009 static void 1010 server_input_channel_req(int type, u_int32_t seq, void *ctxt) 1011 { 1012 Channel *c; 1013 int id, reply, success = 0; 1014 char *rtype; 1015 1016 id = packet_get_int(); 1017 rtype = packet_get_string(NULL); 1018 reply = packet_get_char(); 1019 1020 debug("server_input_channel_req: channel %d request %s reply %d", 1021 id, rtype, reply); 1022 1023 if ((c = channel_lookup(id)) == NULL) 1024 packet_disconnect("server_input_channel_req: " 1025 "unknown channel %d", id); 1026 if (c->type == SSH_CHANNEL_LARVAL || c->type == SSH_CHANNEL_OPEN) 1027 success = session_input_channel_req(c, rtype); 1028 if (reply) { 1029 packet_start(success ? 1030 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE); 1031 packet_put_int(c->remote_id); 1032 packet_send(); 1033 } 1034 xfree(rtype); 1035 } 1036 1037 static void 1038 server_init_dispatch_20(void) 1039 { 1040 debug("server_init_dispatch_20"); 1041 dispatch_init(&dispatch_protocol_error); 1042 dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); 1043 dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data); 1044 dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); 1045 dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); 1046 dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open); 1047 dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 1048 dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 1049 dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req); 1050 dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); 1051 dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request); 1052 /* client_alive */ 1053 dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_channel_failure); 1054 /* rekeying */ 1055 dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); 1056 } 1057 static void 1058 server_init_dispatch_13(void) 1059 { 1060 debug("server_init_dispatch_13"); 1061 dispatch_init(NULL); 1062 dispatch_set(SSH_CMSG_EOF, &server_input_eof); 1063 dispatch_set(SSH_CMSG_STDIN_DATA, &server_input_stdin_data); 1064 dispatch_set(SSH_CMSG_WINDOW_SIZE, &server_input_window_size); 1065 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close); 1066 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation); 1067 dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data); 1068 dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 1069 dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 1070 dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open); 1071 } 1072 static void 1073 server_init_dispatch_15(void) 1074 { 1075 server_init_dispatch_13(); 1076 debug("server_init_dispatch_15"); 1077 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof); 1078 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_oclose); 1079 } 1080 static void 1081 server_init_dispatch(void) 1082 { 1083 if (compat20) 1084 server_init_dispatch_20(); 1085 else if (compat13) 1086 server_init_dispatch_13(); 1087 else 1088 server_init_dispatch_15(); 1089 } 1090