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 1.93 2001/12/28 15:06:00 markus Exp $"); 39 40 #include "xmalloc.h" 41 #include "packet.h" 42 #include "buffer.h" 43 #include "log.h" 44 #include "servconf.h" 45 #include "sshpty.h" 46 #include "channels.h" 47 #include "compat.h" 48 #include "ssh1.h" 49 #include "ssh2.h" 50 #include "auth.h" 51 #include "session.h" 52 #include "dispatch.h" 53 #include "auth-options.h" 54 #include "serverloop.h" 55 #include "misc.h" 56 #include "kex.h" 57 58 extern ServerOptions options; 59 60 /* XXX */ 61 extern Kex *xxx_kex; 62 static Authctxt *xxx_authctxt; 63 64 static Buffer stdin_buffer; /* Buffer for stdin data. */ 65 static Buffer stdout_buffer; /* Buffer for stdout data. */ 66 static Buffer stderr_buffer; /* Buffer for stderr data. */ 67 static int fdin; /* Descriptor for stdin (for writing) */ 68 static int fdout; /* Descriptor for stdout (for reading); 69 May be same number as fdin. */ 70 static int fderr; /* Descriptor for stderr. May be -1. */ 71 static long stdin_bytes = 0; /* Number of bytes written to stdin. */ 72 static long stdout_bytes = 0; /* Number of stdout bytes sent to client. */ 73 static long stderr_bytes = 0; /* Number of stderr bytes sent to client. */ 74 static long fdout_bytes = 0; /* Number of stdout bytes read from program. */ 75 static int stdin_eof = 0; /* EOF message received from client. */ 76 static int fdout_eof = 0; /* EOF encountered reading from fdout. */ 77 static int fderr_eof = 0; /* EOF encountered readung from fderr. */ 78 static int fdin_is_tty = 0; /* fdin points to a tty. */ 79 static int connection_in; /* Connection to client (input). */ 80 static int connection_out; /* Connection to client (output). */ 81 static int connection_closed = 0; /* Connection to client closed. */ 82 static u_int buffer_high; /* "Soft" max buffer size. */ 83 static int client_alive_timeouts = 0; 84 85 /* 86 * This SIGCHLD kludge is used to detect when the child exits. The server 87 * will exit after that, as soon as forwarded connections have terminated. 88 */ 89 90 static volatile sig_atomic_t child_terminated = 0; /* The child has terminated. */ 91 92 /* prototypes */ 93 static void server_init_dispatch(void); 94 95 /* 96 * we write to this pipe if a SIGCHLD is caught in order to avoid 97 * the race between select() and child_terminated 98 */ 99 static int notify_pipe[2]; 100 static void 101 notify_setup(void) 102 { 103 if (pipe(notify_pipe) < 0) { 104 error("pipe(notify_pipe) failed %s", strerror(errno)); 105 } else if ((fcntl(notify_pipe[0], F_SETFD, 1) == -1) || 106 (fcntl(notify_pipe[1], F_SETFD, 1) == -1)) { 107 error("fcntl(notify_pipe, F_SETFD) failed %s", strerror(errno)); 108 close(notify_pipe[0]); 109 close(notify_pipe[1]); 110 } else { 111 set_nonblock(notify_pipe[0]); 112 set_nonblock(notify_pipe[1]); 113 return; 114 } 115 notify_pipe[0] = -1; /* read end */ 116 notify_pipe[1] = -1; /* write end */ 117 } 118 static void 119 notify_parent(void) 120 { 121 if (notify_pipe[1] != -1) 122 write(notify_pipe[1], "", 1); 123 } 124 static void 125 notify_prepare(fd_set *readset) 126 { 127 if (notify_pipe[0] != -1) 128 FD_SET(notify_pipe[0], readset); 129 } 130 static void 131 notify_done(fd_set *readset) 132 { 133 char c; 134 135 if (notify_pipe[0] != -1 && FD_ISSET(notify_pipe[0], readset)) 136 while (read(notify_pipe[0], &c, 1) != -1) 137 debug2("notify_done: reading"); 138 } 139 140 static void 141 sigchld_handler(int sig) 142 { 143 int save_errno = errno; 144 debug("Received SIGCHLD."); 145 child_terminated = 1; 146 signal(SIGCHLD, sigchld_handler); 147 notify_parent(); 148 errno = save_errno; 149 } 150 151 /* 152 * Make packets from buffered stderr data, and buffer it for sending 153 * to the client. 154 */ 155 static void 156 make_packets_from_stderr_data(void) 157 { 158 int len; 159 160 /* Send buffered stderr data to the client. */ 161 while (buffer_len(&stderr_buffer) > 0 && 162 packet_not_very_much_data_to_write()) { 163 len = buffer_len(&stderr_buffer); 164 if (packet_is_interactive()) { 165 if (len > 512) 166 len = 512; 167 } else { 168 /* Keep the packets at reasonable size. */ 169 if (len > packet_get_maxsize()) 170 len = packet_get_maxsize(); 171 } 172 packet_start(SSH_SMSG_STDERR_DATA); 173 packet_put_string(buffer_ptr(&stderr_buffer), len); 174 packet_send(); 175 buffer_consume(&stderr_buffer, len); 176 stderr_bytes += len; 177 } 178 } 179 180 /* 181 * Make packets from buffered stdout data, and buffer it for sending to the 182 * client. 183 */ 184 static void 185 make_packets_from_stdout_data(void) 186 { 187 int len; 188 189 /* Send buffered stdout data to the client. */ 190 while (buffer_len(&stdout_buffer) > 0 && 191 packet_not_very_much_data_to_write()) { 192 len = buffer_len(&stdout_buffer); 193 if (packet_is_interactive()) { 194 if (len > 512) 195 len = 512; 196 } else { 197 /* Keep the packets at reasonable size. */ 198 if (len > packet_get_maxsize()) 199 len = packet_get_maxsize(); 200 } 201 packet_start(SSH_SMSG_STDOUT_DATA); 202 packet_put_string(buffer_ptr(&stdout_buffer), len); 203 packet_send(); 204 buffer_consume(&stdout_buffer, len); 205 stdout_bytes += len; 206 } 207 } 208 209 static void 210 client_alive_check(void) 211 { 212 int id; 213 214 /* timeout, check to see how many we have had */ 215 if (++client_alive_timeouts > options.client_alive_count_max) 216 packet_disconnect("Timeout, your session not responding."); 217 218 id = channel_find_open(); 219 if (id == -1) 220 packet_disconnect("No open channels after timeout!"); 221 /* 222 * send a bogus channel request with "wantreply", 223 * we should get back a failure 224 */ 225 channel_request_start(id, "keepalive@openssh.com", 1); 226 packet_send(); 227 } 228 229 /* 230 * Sleep in select() until we can do something. This will initialize the 231 * select masks. Upon return, the masks will indicate which descriptors 232 * have data or can accept data. Optionally, a maximum time can be specified 233 * for the duration of the wait (0 = infinite). 234 */ 235 static void 236 wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp, 237 int *nallocp, u_int max_time_milliseconds) 238 { 239 struct timeval tv, *tvp; 240 int ret; 241 int client_alive_scheduled = 0; 242 243 /* 244 * if using client_alive, set the max timeout accordingly, 245 * and indicate that this particular timeout was for client 246 * alive by setting the client_alive_scheduled flag. 247 * 248 * this could be randomized somewhat to make traffic 249 * analysis more difficult, but we're not doing it yet. 250 */ 251 if (compat20 && 252 max_time_milliseconds == 0 && options.client_alive_interval) { 253 client_alive_scheduled = 1; 254 max_time_milliseconds = options.client_alive_interval * 1000; 255 } 256 257 /* Allocate and update select() masks for channel descriptors. */ 258 channel_prepare_select(readsetp, writesetp, maxfdp, nallocp, 0); 259 260 if (compat20) { 261 #if 0 262 /* wrong: bad condition XXX */ 263 if (channel_not_very_much_buffered_data()) 264 #endif 265 FD_SET(connection_in, *readsetp); 266 } else { 267 /* 268 * Read packets from the client unless we have too much 269 * buffered stdin or channel data. 270 */ 271 if (buffer_len(&stdin_buffer) < buffer_high && 272 channel_not_very_much_buffered_data()) 273 FD_SET(connection_in, *readsetp); 274 /* 275 * If there is not too much data already buffered going to 276 * the client, try to get some more data from the program. 277 */ 278 if (packet_not_very_much_data_to_write()) { 279 if (!fdout_eof) 280 FD_SET(fdout, *readsetp); 281 if (!fderr_eof) 282 FD_SET(fderr, *readsetp); 283 } 284 /* 285 * If we have buffered data, try to write some of that data 286 * to the program. 287 */ 288 if (fdin != -1 && buffer_len(&stdin_buffer) > 0) 289 FD_SET(fdin, *writesetp); 290 } 291 notify_prepare(*readsetp); 292 293 /* 294 * If we have buffered packet data going to the client, mark that 295 * descriptor. 296 */ 297 if (packet_have_data_to_write()) 298 FD_SET(connection_out, *writesetp); 299 300 /* 301 * If child has terminated and there is enough buffer space to read 302 * from it, then read as much as is available and exit. 303 */ 304 if (child_terminated && packet_not_very_much_data_to_write()) 305 if (max_time_milliseconds == 0 || client_alive_scheduled) 306 max_time_milliseconds = 100; 307 308 if (max_time_milliseconds == 0) 309 tvp = NULL; 310 else { 311 tv.tv_sec = max_time_milliseconds / 1000; 312 tv.tv_usec = 1000 * (max_time_milliseconds % 1000); 313 tvp = &tv; 314 } 315 if (tvp!=NULL) 316 debug3("tvp!=NULL kid %d mili %d", (int) child_terminated, 317 max_time_milliseconds); 318 319 /* Wait for something to happen, or the timeout to expire. */ 320 ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp); 321 322 if (ret == -1) { 323 memset(*readsetp, 0, *nallocp); 324 memset(*writesetp, 0, *nallocp); 325 if (errno != EINTR) 326 error("select: %.100s", strerror(errno)); 327 } else if (ret == 0 && client_alive_scheduled) 328 client_alive_check(); 329 330 notify_done(*readsetp); 331 } 332 333 /* 334 * Processes input from the client and the program. Input data is stored 335 * in buffers and processed later. 336 */ 337 static void 338 process_input(fd_set * readset) 339 { 340 int len; 341 char buf[16384]; 342 343 /* Read and buffer any input data from the client. */ 344 if (FD_ISSET(connection_in, readset)) { 345 len = read(connection_in, buf, sizeof(buf)); 346 if (len == 0) { 347 verbose("Connection closed by remote host."); 348 connection_closed = 1; 349 if (compat20) 350 return; 351 fatal_cleanup(); 352 } else if (len < 0) { 353 if (errno != EINTR && errno != EAGAIN) { 354 verbose("Read error from remote host: %.100s", strerror(errno)); 355 fatal_cleanup(); 356 } 357 } else { 358 /* Buffer any received data. */ 359 packet_process_incoming(buf, len); 360 } 361 } 362 if (compat20) 363 return; 364 365 /* Read and buffer any available stdout data from the program. */ 366 if (!fdout_eof && FD_ISSET(fdout, readset)) { 367 len = read(fdout, buf, sizeof(buf)); 368 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 369 /* do nothing */ 370 } else if (len <= 0) { 371 fdout_eof = 1; 372 } else { 373 buffer_append(&stdout_buffer, buf, len); 374 fdout_bytes += len; 375 } 376 } 377 /* Read and buffer any available stderr data from the program. */ 378 if (!fderr_eof && FD_ISSET(fderr, readset)) { 379 len = read(fderr, buf, sizeof(buf)); 380 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 381 /* do nothing */ 382 } else if (len <= 0) { 383 fderr_eof = 1; 384 } else { 385 buffer_append(&stderr_buffer, buf, len); 386 } 387 } 388 } 389 390 /* 391 * Sends data from internal buffers to client program stdin. 392 */ 393 static void 394 process_output(fd_set * writeset) 395 { 396 struct termios tio; 397 u_char *data; 398 u_int dlen; 399 int len; 400 401 /* Write buffered data to program stdin. */ 402 if (!compat20 && fdin != -1 && FD_ISSET(fdin, writeset)) { 403 data = buffer_ptr(&stdin_buffer); 404 dlen = buffer_len(&stdin_buffer); 405 len = write(fdin, data, dlen); 406 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 407 /* do nothing */ 408 } else if (len <= 0) { 409 if (fdin != fdout) 410 close(fdin); 411 else 412 shutdown(fdin, SHUT_WR); /* We will no longer send. */ 413 fdin = -1; 414 } else { 415 /* Successful write. */ 416 if (fdin_is_tty && dlen >= 1 && data[0] != '\r' && 417 tcgetattr(fdin, &tio) == 0 && 418 !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) { 419 /* 420 * Simulate echo to reduce the impact of 421 * traffic analysis 422 */ 423 packet_send_ignore(len); 424 packet_send(); 425 } 426 /* Consume the data from the buffer. */ 427 buffer_consume(&stdin_buffer, len); 428 /* Update the count of bytes written to the program. */ 429 stdin_bytes += len; 430 } 431 } 432 /* Send any buffered packet data to the client. */ 433 if (FD_ISSET(connection_out, writeset)) 434 packet_write_poll(); 435 } 436 437 /* 438 * Wait until all buffered output has been sent to the client. 439 * This is used when the program terminates. 440 */ 441 static void 442 drain_output(void) 443 { 444 /* Send any buffered stdout data to the client. */ 445 if (buffer_len(&stdout_buffer) > 0) { 446 packet_start(SSH_SMSG_STDOUT_DATA); 447 packet_put_string(buffer_ptr(&stdout_buffer), 448 buffer_len(&stdout_buffer)); 449 packet_send(); 450 /* Update the count of sent bytes. */ 451 stdout_bytes += buffer_len(&stdout_buffer); 452 } 453 /* Send any buffered stderr data to the client. */ 454 if (buffer_len(&stderr_buffer) > 0) { 455 packet_start(SSH_SMSG_STDERR_DATA); 456 packet_put_string(buffer_ptr(&stderr_buffer), 457 buffer_len(&stderr_buffer)); 458 packet_send(); 459 /* Update the count of sent bytes. */ 460 stderr_bytes += buffer_len(&stderr_buffer); 461 } 462 /* Wait until all buffered data has been written to the client. */ 463 packet_write_wait(); 464 } 465 466 static void 467 process_buffered_input_packets(void) 468 { 469 dispatch_run(DISPATCH_NONBLOCK, NULL, compat20 ? xxx_kex : NULL); 470 } 471 472 /* 473 * Performs the interactive session. This handles data transmission between 474 * the client and the program. Note that the notion of stdin, stdout, and 475 * stderr in this function is sort of reversed: this function writes to 476 * stdin (of the child program), and reads from stdout and stderr (of the 477 * child program). 478 */ 479 void 480 server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg) 481 { 482 fd_set *readset = NULL, *writeset = NULL; 483 int max_fd = 0, nalloc = 0; 484 int wait_status; /* Status returned by wait(). */ 485 pid_t wait_pid; /* pid returned by wait(). */ 486 int waiting_termination = 0; /* Have displayed waiting close message. */ 487 u_int max_time_milliseconds; 488 u_int previous_stdout_buffer_bytes; 489 u_int stdout_buffer_bytes; 490 int type; 491 492 debug("Entering interactive session."); 493 494 /* Initialize the SIGCHLD kludge. */ 495 child_terminated = 0; 496 signal(SIGCHLD, sigchld_handler); 497 498 /* Initialize our global variables. */ 499 fdin = fdin_arg; 500 fdout = fdout_arg; 501 fderr = fderr_arg; 502 503 /* nonblocking IO */ 504 set_nonblock(fdin); 505 set_nonblock(fdout); 506 /* we don't have stderr for interactive terminal sessions, see below */ 507 if (fderr != -1) 508 set_nonblock(fderr); 509 510 if (!(datafellows & SSH_BUG_IGNOREMSG) && isatty(fdin)) 511 fdin_is_tty = 1; 512 513 connection_in = packet_get_connection_in(); 514 connection_out = packet_get_connection_out(); 515 516 notify_setup(); 517 518 previous_stdout_buffer_bytes = 0; 519 520 /* Set approximate I/O buffer size. */ 521 if (packet_is_interactive()) 522 buffer_high = 4096; 523 else 524 buffer_high = 64 * 1024; 525 526 #if 0 527 /* Initialize max_fd to the maximum of the known file descriptors. */ 528 max_fd = MAX(connection_in, connection_out); 529 max_fd = MAX(max_fd, fdin); 530 max_fd = MAX(max_fd, fdout); 531 if (fderr != -1) 532 max_fd = MAX(max_fd, fderr); 533 #endif 534 535 /* Initialize Initialize buffers. */ 536 buffer_init(&stdin_buffer); 537 buffer_init(&stdout_buffer); 538 buffer_init(&stderr_buffer); 539 540 /* 541 * If we have no separate fderr (which is the case when we have a pty 542 * - there we cannot make difference between data sent to stdout and 543 * stderr), indicate that we have seen an EOF from stderr. This way 544 * we don\'t need to check the descriptor everywhere. 545 */ 546 if (fderr == -1) 547 fderr_eof = 1; 548 549 server_init_dispatch(); 550 551 /* Main loop of the server for the interactive session mode. */ 552 for (;;) { 553 554 /* Process buffered packets from the client. */ 555 process_buffered_input_packets(); 556 557 /* 558 * If we have received eof, and there is no more pending 559 * input data, cause a real eof by closing fdin. 560 */ 561 if (stdin_eof && fdin != -1 && buffer_len(&stdin_buffer) == 0) { 562 if (fdin != fdout) 563 close(fdin); 564 else 565 shutdown(fdin, SHUT_WR); /* We will no longer send. */ 566 fdin = -1; 567 } 568 /* Make packets from buffered stderr data to send to the client. */ 569 make_packets_from_stderr_data(); 570 571 /* 572 * Make packets from buffered stdout data to send to the 573 * client. If there is very little to send, this arranges to 574 * not send them now, but to wait a short while to see if we 575 * are getting more data. This is necessary, as some systems 576 * wake up readers from a pty after each separate character. 577 */ 578 max_time_milliseconds = 0; 579 stdout_buffer_bytes = buffer_len(&stdout_buffer); 580 if (stdout_buffer_bytes != 0 && stdout_buffer_bytes < 256 && 581 stdout_buffer_bytes != previous_stdout_buffer_bytes) { 582 /* try again after a while */ 583 max_time_milliseconds = 10; 584 } else { 585 /* Send it now. */ 586 make_packets_from_stdout_data(); 587 } 588 previous_stdout_buffer_bytes = buffer_len(&stdout_buffer); 589 590 /* Send channel data to the client. */ 591 if (packet_not_very_much_data_to_write()) 592 channel_output_poll(); 593 594 /* 595 * Bail out of the loop if the program has closed its output 596 * descriptors, and we have no more data to send to the 597 * client, and there is no pending buffered data. 598 */ 599 if (fdout_eof && fderr_eof && !packet_have_data_to_write() && 600 buffer_len(&stdout_buffer) == 0 && buffer_len(&stderr_buffer) == 0) { 601 if (!channel_still_open()) 602 break; 603 if (!waiting_termination) { 604 const char *s = "Waiting for forwarded connections to terminate...\r\n"; 605 char *cp; 606 waiting_termination = 1; 607 buffer_append(&stderr_buffer, s, strlen(s)); 608 609 /* Display list of open channels. */ 610 cp = channel_open_message(); 611 buffer_append(&stderr_buffer, cp, strlen(cp)); 612 xfree(cp); 613 } 614 } 615 max_fd = MAX(connection_in, connection_out); 616 max_fd = MAX(max_fd, fdin); 617 max_fd = MAX(max_fd, fdout); 618 max_fd = MAX(max_fd, fderr); 619 max_fd = MAX(max_fd, notify_pipe[0]); 620 621 /* Sleep in select() until we can do something. */ 622 wait_until_can_do_something(&readset, &writeset, &max_fd, 623 &nalloc, max_time_milliseconds); 624 625 /* Process any channel events. */ 626 channel_after_select(readset, writeset); 627 628 /* Process input from the client and from program stdout/stderr. */ 629 process_input(readset); 630 631 /* Process output to the client and to program stdin. */ 632 process_output(writeset); 633 } 634 if (readset) 635 xfree(readset); 636 if (writeset) 637 xfree(writeset); 638 639 /* Cleanup and termination code. */ 640 641 /* Wait until all output has been sent to the client. */ 642 drain_output(); 643 644 debug("End of interactive session; stdin %ld, stdout (read %ld, sent %ld), stderr %ld bytes.", 645 stdin_bytes, fdout_bytes, stdout_bytes, stderr_bytes); 646 647 /* Free and clear the buffers. */ 648 buffer_free(&stdin_buffer); 649 buffer_free(&stdout_buffer); 650 buffer_free(&stderr_buffer); 651 652 /* Close the file descriptors. */ 653 if (fdout != -1) 654 close(fdout); 655 fdout = -1; 656 fdout_eof = 1; 657 if (fderr != -1) 658 close(fderr); 659 fderr = -1; 660 fderr_eof = 1; 661 if (fdin != -1) 662 close(fdin); 663 fdin = -1; 664 665 channel_free_all(); 666 667 /* We no longer want our SIGCHLD handler to be called. */ 668 signal(SIGCHLD, SIG_DFL); 669 670 wait_pid = waitpid(-1, &wait_status, child_terminated ? WNOHANG : 0); 671 if (wait_pid == -1) 672 packet_disconnect("wait: %.100s", strerror(errno)); 673 else if (wait_pid != pid) 674 error("Strange, wait returned pid %d, expected %d", 675 wait_pid, pid); 676 677 /* Check if it exited normally. */ 678 if (WIFEXITED(wait_status)) { 679 /* Yes, normal exit. Get exit status and send it to the client. */ 680 debug("Command exited with status %d.", WEXITSTATUS(wait_status)); 681 packet_start(SSH_SMSG_EXITSTATUS); 682 packet_put_int(WEXITSTATUS(wait_status)); 683 packet_send(); 684 packet_write_wait(); 685 686 /* 687 * Wait for exit confirmation. Note that there might be 688 * other packets coming before it; however, the program has 689 * already died so we just ignore them. The client is 690 * supposed to respond with the confirmation when it receives 691 * the exit status. 692 */ 693 do { 694 type = packet_read(); 695 } 696 while (type != SSH_CMSG_EXIT_CONFIRMATION); 697 698 debug("Received exit confirmation."); 699 return; 700 } 701 /* Check if the program terminated due to a signal. */ 702 if (WIFSIGNALED(wait_status)) 703 packet_disconnect("Command terminated on signal %d.", 704 WTERMSIG(wait_status)); 705 706 /* Some weird exit cause. Just exit. */ 707 packet_disconnect("wait returned status %04x.", wait_status); 708 /* NOTREACHED */ 709 } 710 711 static void 712 collect_children(void) 713 { 714 pid_t pid; 715 sigset_t oset, nset; 716 int status; 717 718 /* block SIGCHLD while we check for dead children */ 719 sigemptyset(&nset); 720 sigaddset(&nset, SIGCHLD); 721 sigprocmask(SIG_BLOCK, &nset, &oset); 722 if (child_terminated) { 723 while ((pid = waitpid(-1, &status, WNOHANG)) > 0) 724 session_close_by_pid(pid, status); 725 child_terminated = 0; 726 } 727 sigprocmask(SIG_SETMASK, &oset, NULL); 728 } 729 730 void 731 server_loop2(Authctxt *authctxt) 732 { 733 fd_set *readset = NULL, *writeset = NULL; 734 int rekeying = 0, max_fd, nalloc = 0; 735 736 debug("Entering interactive session for SSH2."); 737 738 signal(SIGCHLD, sigchld_handler); 739 child_terminated = 0; 740 connection_in = packet_get_connection_in(); 741 connection_out = packet_get_connection_out(); 742 743 notify_setup(); 744 745 max_fd = MAX(connection_in, connection_out); 746 max_fd = MAX(max_fd, notify_pipe[0]); 747 748 xxx_authctxt = authctxt; 749 750 server_init_dispatch(); 751 752 for (;;) { 753 process_buffered_input_packets(); 754 755 rekeying = (xxx_kex != NULL && !xxx_kex->done); 756 757 if (!rekeying && packet_not_very_much_data_to_write()) 758 channel_output_poll(); 759 wait_until_can_do_something(&readset, &writeset, &max_fd, 760 &nalloc, 0); 761 762 collect_children(); 763 if (!rekeying) 764 channel_after_select(readset, writeset); 765 process_input(readset); 766 if (connection_closed) 767 break; 768 process_output(writeset); 769 } 770 collect_children(); 771 772 if (readset) 773 xfree(readset); 774 if (writeset) 775 xfree(writeset); 776 777 /* free all channels, no more reads and writes */ 778 channel_free_all(); 779 780 /* free remaining sessions, e.g. remove wtmp entries */ 781 session_destroy_all(); 782 } 783 784 static void 785 server_input_channel_failure(int type, u_int32_t seq, void *ctxt) 786 { 787 debug("Got CHANNEL_FAILURE for keepalive"); 788 /* 789 * reset timeout, since we got a sane answer from the client. 790 * even if this was generated by something other than 791 * the bogus CHANNEL_REQUEST we send for keepalives. 792 */ 793 client_alive_timeouts = 0; 794 } 795 796 797 static void 798 server_input_stdin_data(int type, u_int32_t seq, void *ctxt) 799 { 800 char *data; 801 u_int data_len; 802 803 /* Stdin data from the client. Append it to the buffer. */ 804 /* Ignore any data if the client has closed stdin. */ 805 if (fdin == -1) 806 return; 807 data = packet_get_string(&data_len); 808 packet_check_eom(); 809 buffer_append(&stdin_buffer, data, data_len); 810 memset(data, 0, data_len); 811 xfree(data); 812 } 813 814 static void 815 server_input_eof(int type, u_int32_t seq, void *ctxt) 816 { 817 /* 818 * Eof from the client. The stdin descriptor to the 819 * program will be closed when all buffered data has 820 * drained. 821 */ 822 debug("EOF received for stdin."); 823 packet_check_eom(); 824 stdin_eof = 1; 825 } 826 827 static void 828 server_input_window_size(int type, u_int32_t seq, void *ctxt) 829 { 830 int row = packet_get_int(); 831 int col = packet_get_int(); 832 int xpixel = packet_get_int(); 833 int ypixel = packet_get_int(); 834 835 debug("Window change received."); 836 packet_check_eom(); 837 if (fdin != -1) 838 pty_change_window_size(fdin, row, col, xpixel, ypixel); 839 } 840 841 static Channel * 842 server_request_direct_tcpip(char *ctype) 843 { 844 Channel *c; 845 int sock; 846 char *target, *originator; 847 int target_port, originator_port; 848 849 target = packet_get_string(NULL); 850 target_port = packet_get_int(); 851 originator = packet_get_string(NULL); 852 originator_port = packet_get_int(); 853 packet_check_eom(); 854 855 debug("server_request_direct_tcpip: originator %s port %d, target %s port %d", 856 originator, originator_port, target, target_port); 857 858 /* XXX check permission */ 859 sock = channel_connect_to(target, target_port); 860 xfree(target); 861 xfree(originator); 862 if (sock < 0) 863 return NULL; 864 c = channel_new(ctype, SSH_CHANNEL_CONNECTING, 865 sock, sock, -1, CHAN_TCP_WINDOW_DEFAULT, 866 CHAN_TCP_PACKET_DEFAULT, 0, xstrdup("direct-tcpip"), 1); 867 if (c == NULL) { 868 error("server_request_direct_tcpip: channel_new failed"); 869 close(sock); 870 } 871 return c; 872 } 873 874 static Channel * 875 server_request_session(char *ctype) 876 { 877 Channel *c; 878 879 debug("input_session_request"); 880 packet_check_eom(); 881 /* 882 * A server session has no fd to read or write until a 883 * CHANNEL_REQUEST for a shell is made, so we set the type to 884 * SSH_CHANNEL_LARVAL. Additionally, a callback for handling all 885 * CHANNEL_REQUEST messages is registered. 886 */ 887 c = channel_new(ctype, SSH_CHANNEL_LARVAL, 888 -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT, 889 0, xstrdup("server-session"), 1); 890 if (c == NULL) { 891 error("server_request_session: channel_new failed"); 892 return NULL; 893 } 894 if (session_open(xxx_authctxt, c->self) != 1) { 895 debug("session open failed, free channel %d", c->self); 896 channel_free(c); 897 return NULL; 898 } 899 channel_register_callback(c->self, SSH2_MSG_CHANNEL_REQUEST, 900 session_input_channel_req, (void *)0); 901 channel_register_cleanup(c->self, session_close_by_channel); 902 return c; 903 } 904 905 static void 906 server_input_channel_open(int type, u_int32_t seq, void *ctxt) 907 { 908 Channel *c = NULL; 909 char *ctype; 910 u_int len; 911 int rchan; 912 int rmaxpack; 913 int rwindow; 914 915 ctype = packet_get_string(&len); 916 rchan = packet_get_int(); 917 rwindow = packet_get_int(); 918 rmaxpack = packet_get_int(); 919 920 debug("server_input_channel_open: ctype %s rchan %d win %d max %d", 921 ctype, rchan, rwindow, rmaxpack); 922 923 if (strcmp(ctype, "session") == 0) { 924 c = server_request_session(ctype); 925 } else if (strcmp(ctype, "direct-tcpip") == 0) { 926 c = server_request_direct_tcpip(ctype); 927 } 928 if (c != NULL) { 929 debug("server_input_channel_open: confirm %s", ctype); 930 c->remote_id = rchan; 931 c->remote_window = rwindow; 932 c->remote_maxpacket = rmaxpack; 933 if (c->type != SSH_CHANNEL_CONNECTING) { 934 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION); 935 packet_put_int(c->remote_id); 936 packet_put_int(c->self); 937 packet_put_int(c->local_window); 938 packet_put_int(c->local_maxpacket); 939 packet_send(); 940 } 941 } else { 942 debug("server_input_channel_open: failure %s", ctype); 943 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE); 944 packet_put_int(rchan); 945 packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED); 946 if (!(datafellows & SSH_BUG_OPENFAILURE)) { 947 packet_put_cstring("open failed"); 948 packet_put_cstring(""); 949 } 950 packet_send(); 951 } 952 xfree(ctype); 953 } 954 955 static void 956 server_input_global_request(int type, u_int32_t seq, void *ctxt) 957 { 958 char *rtype; 959 int want_reply; 960 int success = 0; 961 962 rtype = packet_get_string(NULL); 963 want_reply = packet_get_char(); 964 debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply); 965 966 /* -R style forwarding */ 967 if (strcmp(rtype, "tcpip-forward") == 0) { 968 struct passwd *pw; 969 char *listen_address; 970 u_short listen_port; 971 972 pw = auth_get_user(); 973 if (pw == NULL) 974 fatal("server_input_global_request: no user"); 975 listen_address = packet_get_string(NULL); /* XXX currently ignored */ 976 listen_port = (u_short)packet_get_int(); 977 debug("server_input_global_request: tcpip-forward listen %s port %d", 978 listen_address, listen_port); 979 980 /* check permissions */ 981 if (!options.allow_tcp_forwarding || 982 no_port_forwarding_flag || 983 (listen_port < IPPORT_RESERVED && pw->pw_uid != 0)) { 984 success = 0; 985 packet_send_debug("Server has disabled port forwarding."); 986 } else { 987 /* Start listening on the port */ 988 success = channel_request_forwarding( 989 listen_address, listen_port, 990 /*unspec host_to_connect*/ "<unspec host>", 991 /*unspec port_to_connect*/ 0, 992 options.gateway_ports, /*remote*/ 1); 993 } 994 xfree(listen_address); 995 } 996 if (want_reply) { 997 packet_start(success ? 998 SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE); 999 packet_send(); 1000 packet_write_wait(); 1001 } 1002 xfree(rtype); 1003 } 1004 1005 static void 1006 server_init_dispatch_20(void) 1007 { 1008 debug("server_init_dispatch_20"); 1009 dispatch_init(&dispatch_protocol_error); 1010 dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); 1011 dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data); 1012 dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); 1013 dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); 1014 dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open); 1015 dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 1016 dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 1017 dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &channel_input_channel_request); 1018 dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); 1019 dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request); 1020 /* client_alive */ 1021 dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_channel_failure); 1022 /* rekeying */ 1023 dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); 1024 } 1025 static void 1026 server_init_dispatch_13(void) 1027 { 1028 debug("server_init_dispatch_13"); 1029 dispatch_init(NULL); 1030 dispatch_set(SSH_CMSG_EOF, &server_input_eof); 1031 dispatch_set(SSH_CMSG_STDIN_DATA, &server_input_stdin_data); 1032 dispatch_set(SSH_CMSG_WINDOW_SIZE, &server_input_window_size); 1033 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close); 1034 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation); 1035 dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data); 1036 dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 1037 dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 1038 dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open); 1039 } 1040 static void 1041 server_init_dispatch_15(void) 1042 { 1043 server_init_dispatch_13(); 1044 debug("server_init_dispatch_15"); 1045 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof); 1046 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_oclose); 1047 } 1048 static void 1049 server_init_dispatch(void) 1050 { 1051 if (compat20) 1052 server_init_dispatch_20(); 1053 else if (compat13) 1054 server_init_dispatch_13(); 1055 else 1056 server_init_dispatch_15(); 1057 } 1058