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 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("$FreeBSD$"); 39 RCSID("$OpenBSD: serverloop.c,v 1.61 2001/04/13 22:46:54 beck Exp $"); 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 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 84 /* 85 * This SIGCHLD kludge is used to detect when the child exits. The server 86 * will exit after that, as soon as forwarded connections have terminated. 87 */ 88 89 static pid_t child_pid; /* Pid of the child. */ 90 static volatile int child_terminated; /* The child has terminated. */ 91 static volatile int child_wait_status; /* Status from wait(). */ 92 93 void server_init_dispatch(void); 94 95 int client_alive_timeouts = 0; 96 97 void 98 sigchld_handler(int sig) 99 { 100 int save_errno = errno; 101 pid_t wait_pid; 102 103 debug("Received SIGCHLD."); 104 wait_pid = wait((int *) &child_wait_status); 105 if (wait_pid != -1) { 106 if (wait_pid != child_pid) 107 error("Strange, got SIGCHLD and wait returned pid %d but child is %d", 108 wait_pid, child_pid); 109 if (WIFEXITED(child_wait_status) || 110 WIFSIGNALED(child_wait_status)) 111 child_terminated = 1; 112 } 113 signal(SIGCHLD, sigchld_handler); 114 errno = save_errno; 115 } 116 void 117 sigchld_handler2(int sig) 118 { 119 int save_errno = errno; 120 debug("Received SIGCHLD."); 121 child_terminated = 1; 122 signal(SIGCHLD, sigchld_handler2); 123 errno = save_errno; 124 } 125 126 /* 127 * Make packets from buffered stderr data, and buffer it for sending 128 * to the client. 129 */ 130 void 131 make_packets_from_stderr_data(void) 132 { 133 int len; 134 135 /* Send buffered stderr data to the client. */ 136 while (buffer_len(&stderr_buffer) > 0 && 137 packet_not_very_much_data_to_write()) { 138 len = buffer_len(&stderr_buffer); 139 if (packet_is_interactive()) { 140 if (len > 512) 141 len = 512; 142 } else { 143 /* Keep the packets at reasonable size. */ 144 if (len > packet_get_maxsize()) 145 len = packet_get_maxsize(); 146 } 147 packet_start(SSH_SMSG_STDERR_DATA); 148 packet_put_string(buffer_ptr(&stderr_buffer), len); 149 packet_send(); 150 buffer_consume(&stderr_buffer, len); 151 stderr_bytes += len; 152 } 153 } 154 155 /* 156 * Make packets from buffered stdout data, and buffer it for sending to the 157 * client. 158 */ 159 void 160 make_packets_from_stdout_data(void) 161 { 162 int len; 163 164 /* Send buffered stdout data to the client. */ 165 while (buffer_len(&stdout_buffer) > 0 && 166 packet_not_very_much_data_to_write()) { 167 len = buffer_len(&stdout_buffer); 168 if (packet_is_interactive()) { 169 if (len > 512) 170 len = 512; 171 } else { 172 /* Keep the packets at reasonable size. */ 173 if (len > packet_get_maxsize()) 174 len = packet_get_maxsize(); 175 } 176 packet_start(SSH_SMSG_STDOUT_DATA); 177 packet_put_string(buffer_ptr(&stdout_buffer), len); 178 packet_send(); 179 buffer_consume(&stdout_buffer, len); 180 stdout_bytes += len; 181 } 182 } 183 184 /* 185 * Sleep in select() until we can do something. This will initialize the 186 * select masks. Upon return, the masks will indicate which descriptors 187 * have data or can accept data. Optionally, a maximum time can be specified 188 * for the duration of the wait (0 = infinite). 189 */ 190 void 191 wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp, 192 u_int max_time_milliseconds) 193 { 194 struct timeval tv, *tvp; 195 int ret; 196 int client_alive_scheduled = 0; 197 198 /* 199 * if using client_alive, set the max timeout accordingly, 200 * and indicate that this particular timeout was for client 201 * alive by setting the client_alive_scheduled flag. 202 * 203 * this could be randomized somewhat to make traffic 204 * analysis more difficult, but we're not doing it yet. 205 */ 206 if (max_time_milliseconds == 0 && options.client_alive_interval) { 207 client_alive_scheduled = 1; 208 max_time_milliseconds = options.client_alive_interval * 1000; 209 } else 210 client_alive_scheduled = 0; 211 212 /* When select fails we restart from here. */ 213 retry_select: 214 215 /* Allocate and update select() masks for channel descriptors. */ 216 channel_prepare_select(readsetp, writesetp, maxfdp, 0); 217 218 if (compat20) { 219 /* wrong: bad condition XXX */ 220 if (channel_not_very_much_buffered_data()) 221 FD_SET(connection_in, *readsetp); 222 } else { 223 /* 224 * Read packets from the client unless we have too much 225 * buffered stdin or channel data. 226 */ 227 if (buffer_len(&stdin_buffer) < buffer_high && 228 channel_not_very_much_buffered_data()) 229 FD_SET(connection_in, *readsetp); 230 /* 231 * If there is not too much data already buffered going to 232 * the client, try to get some more data from the program. 233 */ 234 if (packet_not_very_much_data_to_write()) { 235 if (!fdout_eof) 236 FD_SET(fdout, *readsetp); 237 if (!fderr_eof) 238 FD_SET(fderr, *readsetp); 239 } 240 /* 241 * If we have buffered data, try to write some of that data 242 * to the program. 243 */ 244 if (fdin != -1 && buffer_len(&stdin_buffer) > 0) 245 FD_SET(fdin, *writesetp); 246 } 247 248 /* 249 * If we have buffered packet data going to the client, mark that 250 * descriptor. 251 */ 252 if (packet_have_data_to_write()) 253 FD_SET(connection_out, *writesetp); 254 255 /* 256 * If child has terminated and there is enough buffer space to read 257 * from it, then read as much as is available and exit. 258 */ 259 if (child_terminated && packet_not_very_much_data_to_write()) 260 if (max_time_milliseconds == 0 || client_alive_scheduled) 261 max_time_milliseconds = 100; 262 263 if (max_time_milliseconds == 0) 264 tvp = NULL; 265 else { 266 tv.tv_sec = max_time_milliseconds / 1000; 267 tv.tv_usec = 1000 * (max_time_milliseconds % 1000); 268 tvp = &tv; 269 } 270 if (tvp!=NULL) 271 debug3("tvp!=NULL kid %d mili %d", child_terminated, max_time_milliseconds); 272 273 /* Wait for something to happen, or the timeout to expire. */ 274 ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp); 275 276 if (ret == -1) { 277 if (errno != EINTR) 278 error("select: %.100s", strerror(errno)); 279 else 280 goto retry_select; 281 } 282 if (ret == 0 && client_alive_scheduled) { 283 /* timeout, check to see how many we have had */ 284 client_alive_timeouts++; 285 286 if (client_alive_timeouts > options.client_alive_count_max ) { 287 packet_disconnect( 288 "Timeout, your session not responding."); 289 } else { 290 /* 291 * send a bogus channel request with "wantreply" 292 * we should get back a failure 293 */ 294 int id; 295 296 id = channel_find_open(); 297 if (id != -1) { 298 channel_request_start(id, 299 "keepalive@openssh.com", 1); 300 packet_send(); 301 } else 302 packet_disconnect( 303 "No open channels after timeout!"); 304 } 305 } 306 } 307 308 /* 309 * Processes input from the client and the program. Input data is stored 310 * in buffers and processed later. 311 */ 312 void 313 process_input(fd_set * readset) 314 { 315 int len; 316 char buf[16384]; 317 318 /* Read and buffer any input data from the client. */ 319 if (FD_ISSET(connection_in, readset)) { 320 len = read(connection_in, buf, sizeof(buf)); 321 if (len == 0) { 322 verbose("Connection closed by remote host."); 323 connection_closed = 1; 324 if (compat20) 325 return; 326 fatal_cleanup(); 327 } else if (len < 0) { 328 if (errno != EINTR && errno != EAGAIN) { 329 verbose("Read error from remote host: %.100s", strerror(errno)); 330 fatal_cleanup(); 331 } 332 } else { 333 /* Buffer any received data. */ 334 packet_process_incoming(buf, len); 335 } 336 } 337 if (compat20) 338 return; 339 340 /* Read and buffer any available stdout data from the program. */ 341 if (!fdout_eof && FD_ISSET(fdout, readset)) { 342 len = read(fdout, buf, sizeof(buf)); 343 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 344 /* do nothing */ 345 } else if (len <= 0) { 346 fdout_eof = 1; 347 } else { 348 buffer_append(&stdout_buffer, buf, len); 349 fdout_bytes += len; 350 } 351 } 352 /* Read and buffer any available stderr data from the program. */ 353 if (!fderr_eof && FD_ISSET(fderr, readset)) { 354 len = read(fderr, buf, sizeof(buf)); 355 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 356 /* do nothing */ 357 } else if (len <= 0) { 358 fderr_eof = 1; 359 } else { 360 buffer_append(&stderr_buffer, buf, len); 361 } 362 } 363 } 364 365 /* 366 * Sends data from internal buffers to client program stdin. 367 */ 368 void 369 process_output(fd_set * writeset) 370 { 371 struct termios tio; 372 int len; 373 374 /* Write buffered data to program stdin. */ 375 if (!compat20 && fdin != -1 && FD_ISSET(fdin, writeset)) { 376 len = write(fdin, buffer_ptr(&stdin_buffer), 377 buffer_len(&stdin_buffer)); 378 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 379 /* do nothing */ 380 } else if (len <= 0) { 381 #ifdef USE_PIPES 382 close(fdin); 383 #else 384 if (fdin != fdout) 385 close(fdin); 386 else 387 shutdown(fdin, SHUT_WR); /* We will no longer send. */ 388 #endif 389 fdin = -1; 390 } else { 391 /* Successful write. */ 392 if (fdin_is_tty && tcgetattr(fdin, &tio) == 0 && 393 !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) { 394 /* 395 * Simulate echo to reduce the impact of 396 * traffic analysis 397 */ 398 packet_send_ignore(len); 399 packet_send(); 400 } 401 /* Consume the data from the buffer. */ 402 buffer_consume(&stdin_buffer, len); 403 /* Update the count of bytes written to the program. */ 404 stdin_bytes += len; 405 } 406 } 407 /* Send any buffered packet data to the client. */ 408 if (FD_ISSET(connection_out, writeset)) 409 packet_write_poll(); 410 } 411 412 /* 413 * Wait until all buffered output has been sent to the client. 414 * This is used when the program terminates. 415 */ 416 void 417 drain_output(void) 418 { 419 /* Send any buffered stdout data to the client. */ 420 if (buffer_len(&stdout_buffer) > 0) { 421 packet_start(SSH_SMSG_STDOUT_DATA); 422 packet_put_string(buffer_ptr(&stdout_buffer), 423 buffer_len(&stdout_buffer)); 424 packet_send(); 425 /* Update the count of sent bytes. */ 426 stdout_bytes += buffer_len(&stdout_buffer); 427 } 428 /* Send any buffered stderr data to the client. */ 429 if (buffer_len(&stderr_buffer) > 0) { 430 packet_start(SSH_SMSG_STDERR_DATA); 431 packet_put_string(buffer_ptr(&stderr_buffer), 432 buffer_len(&stderr_buffer)); 433 packet_send(); 434 /* Update the count of sent bytes. */ 435 stderr_bytes += buffer_len(&stderr_buffer); 436 } 437 /* Wait until all buffered data has been written to the client. */ 438 packet_write_wait(); 439 } 440 441 void 442 process_buffered_input_packets(void) 443 { 444 dispatch_run(DISPATCH_NONBLOCK, NULL, compat20 ? xxx_kex : NULL); 445 } 446 447 /* 448 * Performs the interactive session. This handles data transmission between 449 * the client and the program. Note that the notion of stdin, stdout, and 450 * stderr in this function is sort of reversed: this function writes to 451 * stdin (of the child program), and reads from stdout and stderr (of the 452 * child program). 453 */ 454 void 455 server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg) 456 { 457 fd_set *readset = NULL, *writeset = NULL; 458 int max_fd; 459 int wait_status; /* Status returned by wait(). */ 460 pid_t wait_pid; /* pid returned by wait(). */ 461 int waiting_termination = 0; /* Have displayed waiting close message. */ 462 u_int max_time_milliseconds; 463 u_int previous_stdout_buffer_bytes; 464 u_int stdout_buffer_bytes; 465 int type; 466 467 debug("Entering interactive session."); 468 469 /* Initialize the SIGCHLD kludge. */ 470 child_pid = pid; 471 child_terminated = 0; 472 signal(SIGCHLD, sigchld_handler); 473 474 /* Initialize our global variables. */ 475 fdin = fdin_arg; 476 fdout = fdout_arg; 477 fderr = fderr_arg; 478 479 /* nonblocking IO */ 480 set_nonblock(fdin); 481 set_nonblock(fdout); 482 /* we don't have stderr for interactive terminal sessions, see below */ 483 if (fderr != -1) 484 set_nonblock(fderr); 485 486 if (!(datafellows & SSH_BUG_IGNOREMSG) && isatty(fdin)) 487 fdin_is_tty = 1; 488 489 connection_in = packet_get_connection_in(); 490 connection_out = packet_get_connection_out(); 491 492 previous_stdout_buffer_bytes = 0; 493 494 /* Set approximate I/O buffer size. */ 495 if (packet_is_interactive()) 496 buffer_high = 4096; 497 else 498 buffer_high = 64 * 1024; 499 500 /* Initialize max_fd to the maximum of the known file descriptors. */ 501 max_fd = MAX(fdin, fdout); 502 if (fderr != -1) 503 max_fd = MAX(max_fd, fderr); 504 max_fd = MAX(max_fd, connection_in); 505 max_fd = MAX(max_fd, connection_out); 506 507 /* Initialize Initialize buffers. */ 508 buffer_init(&stdin_buffer); 509 buffer_init(&stdout_buffer); 510 buffer_init(&stderr_buffer); 511 512 /* 513 * If we have no separate fderr (which is the case when we have a pty 514 * - there we cannot make difference between data sent to stdout and 515 * stderr), indicate that we have seen an EOF from stderr. This way 516 * we don\'t need to check the descriptor everywhere. 517 */ 518 if (fderr == -1) 519 fderr_eof = 1; 520 521 server_init_dispatch(); 522 523 /* Main loop of the server for the interactive session mode. */ 524 for (;;) { 525 526 /* Process buffered packets from the client. */ 527 process_buffered_input_packets(); 528 529 /* 530 * If we have received eof, and there is no more pending 531 * input data, cause a real eof by closing fdin. 532 */ 533 if (stdin_eof && fdin != -1 && buffer_len(&stdin_buffer) == 0) { 534 #ifdef USE_PIPES 535 close(fdin); 536 #else 537 if (fdin != fdout) 538 close(fdin); 539 else 540 shutdown(fdin, SHUT_WR); /* We will no longer send. */ 541 #endif 542 fdin = -1; 543 } 544 /* Make packets from buffered stderr data to send to the client. */ 545 make_packets_from_stderr_data(); 546 547 /* 548 * Make packets from buffered stdout data to send to the 549 * client. If there is very little to send, this arranges to 550 * not send them now, but to wait a short while to see if we 551 * are getting more data. This is necessary, as some systems 552 * wake up readers from a pty after each separate character. 553 */ 554 max_time_milliseconds = 0; 555 stdout_buffer_bytes = buffer_len(&stdout_buffer); 556 if (stdout_buffer_bytes != 0 && stdout_buffer_bytes < 256 && 557 stdout_buffer_bytes != previous_stdout_buffer_bytes) { 558 /* try again after a while */ 559 max_time_milliseconds = 10; 560 } else { 561 /* Send it now. */ 562 make_packets_from_stdout_data(); 563 } 564 previous_stdout_buffer_bytes = buffer_len(&stdout_buffer); 565 566 /* Send channel data to the client. */ 567 if (packet_not_very_much_data_to_write()) 568 channel_output_poll(); 569 570 /* 571 * Bail out of the loop if the program has closed its output 572 * descriptors, and we have no more data to send to the 573 * client, and there is no pending buffered data. 574 */ 575 if (fdout_eof && fderr_eof && !packet_have_data_to_write() && 576 buffer_len(&stdout_buffer) == 0 && buffer_len(&stderr_buffer) == 0) { 577 if (!channel_still_open()) 578 break; 579 if (!waiting_termination) { 580 const char *s = "Waiting for forwarded connections to terminate...\r\n"; 581 char *cp; 582 waiting_termination = 1; 583 buffer_append(&stderr_buffer, s, strlen(s)); 584 585 /* Display list of open channels. */ 586 cp = channel_open_message(); 587 buffer_append(&stderr_buffer, cp, strlen(cp)); 588 xfree(cp); 589 } 590 } 591 /* Sleep in select() until we can do something. */ 592 wait_until_can_do_something(&readset, &writeset, &max_fd, 593 max_time_milliseconds); 594 595 /* Process any channel events. */ 596 channel_after_select(readset, writeset); 597 598 /* Process input from the client and from program stdout/stderr. */ 599 process_input(readset); 600 601 /* Process output to the client and to program stdin. */ 602 process_output(writeset); 603 } 604 if (readset) 605 xfree(readset); 606 if (writeset) 607 xfree(writeset); 608 609 /* Cleanup and termination code. */ 610 611 /* Wait until all output has been sent to the client. */ 612 drain_output(); 613 614 debug("End of interactive session; stdin %ld, stdout (read %ld, sent %ld), stderr %ld bytes.", 615 stdin_bytes, fdout_bytes, stdout_bytes, stderr_bytes); 616 617 /* Free and clear the buffers. */ 618 buffer_free(&stdin_buffer); 619 buffer_free(&stdout_buffer); 620 buffer_free(&stderr_buffer); 621 622 /* Close the file descriptors. */ 623 if (fdout != -1) 624 close(fdout); 625 fdout = -1; 626 fdout_eof = 1; 627 if (fderr != -1) 628 close(fderr); 629 fderr = -1; 630 fderr_eof = 1; 631 if (fdin != -1) 632 close(fdin); 633 fdin = -1; 634 635 /* Stop listening for channels; this removes unix domain sockets. */ 636 channel_stop_listening(); 637 638 /* Wait for the child to exit. Get its exit status. */ 639 wait_pid = wait(&wait_status); 640 if (wait_pid == -1) { 641 /* 642 * It is possible that the wait was handled by SIGCHLD 643 * handler. This may result in either: this call 644 * returning with EINTR, or: this call returning ECHILD. 645 */ 646 if (child_terminated) 647 wait_status = child_wait_status; 648 else 649 packet_disconnect("wait: %.100s", strerror(errno)); 650 } else { 651 /* Check if it matches the process we forked. */ 652 if (wait_pid != pid) 653 error("Strange, wait returned pid %d, expected %d", 654 wait_pid, pid); 655 } 656 657 /* We no longer want our SIGCHLD handler to be called. */ 658 signal(SIGCHLD, SIG_DFL); 659 660 /* Check if it exited normally. */ 661 if (WIFEXITED(wait_status)) { 662 /* Yes, normal exit. Get exit status and send it to the client. */ 663 debug("Command exited with status %d.", WEXITSTATUS(wait_status)); 664 packet_start(SSH_SMSG_EXITSTATUS); 665 packet_put_int(WEXITSTATUS(wait_status)); 666 packet_send(); 667 packet_write_wait(); 668 669 /* 670 * Wait for exit confirmation. Note that there might be 671 * other packets coming before it; however, the program has 672 * already died so we just ignore them. The client is 673 * supposed to respond with the confirmation when it receives 674 * the exit status. 675 */ 676 do { 677 int plen; 678 type = packet_read(&plen); 679 } 680 while (type != SSH_CMSG_EXIT_CONFIRMATION); 681 682 debug("Received exit confirmation."); 683 return; 684 } 685 /* Check if the program terminated due to a signal. */ 686 if (WIFSIGNALED(wait_status)) 687 packet_disconnect("Command terminated on signal %d.", 688 WTERMSIG(wait_status)); 689 690 /* Some weird exit cause. Just exit. */ 691 packet_disconnect("wait returned status %04x.", wait_status); 692 /* NOTREACHED */ 693 } 694 695 void 696 server_loop2(void) 697 { 698 fd_set *readset = NULL, *writeset = NULL; 699 int rekeying = 0, max_fd, status; 700 pid_t pid; 701 702 debug("Entering interactive session for SSH2."); 703 704 signal(SIGCHLD, sigchld_handler2); 705 child_terminated = 0; 706 connection_in = packet_get_connection_in(); 707 connection_out = packet_get_connection_out(); 708 709 max_fd = MAX(connection_in, connection_out); 710 711 server_init_dispatch(); 712 713 for (;;) { 714 process_buffered_input_packets(); 715 716 rekeying = (xxx_kex != NULL && !xxx_kex->done); 717 718 if (!rekeying && packet_not_very_much_data_to_write()) 719 channel_output_poll(); 720 wait_until_can_do_something(&readset, &writeset, &max_fd, 721 rekeying); 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 if (!rekeying) 728 channel_after_select(readset, writeset); 729 process_input(readset); 730 if (connection_closed) 731 break; 732 process_output(writeset); 733 } 734 if (readset) 735 xfree(readset); 736 if (writeset) 737 xfree(writeset); 738 739 signal(SIGCHLD, SIG_DFL); 740 while ((pid = waitpid(-1, &status, WNOHANG)) > 0) 741 session_close_by_pid(pid, status); 742 channel_stop_listening(); 743 } 744 745 void 746 server_input_channel_failure(int type, int plen, void *ctxt) 747 { 748 debug("Got CHANNEL_FAILURE for keepalive"); 749 /* 750 * reset timeout, since we got a sane answer from the client. 751 * even if this was generated by something other than 752 * the bogus CHANNEL_REQUEST we send for keepalives. 753 */ 754 client_alive_timeouts = 0; 755 } 756 757 758 void 759 server_input_stdin_data(int type, int plen, void *ctxt) 760 { 761 char *data; 762 u_int data_len; 763 764 /* Stdin data from the client. Append it to the buffer. */ 765 /* Ignore any data if the client has closed stdin. */ 766 if (fdin == -1) 767 return; 768 data = packet_get_string(&data_len); 769 packet_integrity_check(plen, (4 + data_len), type); 770 buffer_append(&stdin_buffer, data, data_len); 771 memset(data, 0, data_len); 772 xfree(data); 773 } 774 775 void 776 server_input_eof(int type, int plen, void *ctxt) 777 { 778 /* 779 * Eof from the client. The stdin descriptor to the 780 * program will be closed when all buffered data has 781 * drained. 782 */ 783 debug("EOF received for stdin."); 784 packet_integrity_check(plen, 0, type); 785 stdin_eof = 1; 786 } 787 788 void 789 server_input_window_size(int type, int plen, void *ctxt) 790 { 791 int row = packet_get_int(); 792 int col = packet_get_int(); 793 int xpixel = packet_get_int(); 794 int ypixel = packet_get_int(); 795 796 debug("Window change received."); 797 packet_integrity_check(plen, 4 * 4, type); 798 if (fdin != -1) 799 pty_change_window_size(fdin, row, col, xpixel, ypixel); 800 } 801 802 Channel * 803 server_request_direct_tcpip(char *ctype) 804 { 805 int sock, newch; 806 char *target, *originator; 807 int target_port, originator_port; 808 809 target = packet_get_string(NULL); 810 target_port = packet_get_int(); 811 originator = packet_get_string(NULL); 812 originator_port = packet_get_int(); 813 packet_done(); 814 815 debug("server_request_direct_tcpip: originator %s port %d, target %s port %d", 816 originator, originator_port, target, target_port); 817 818 /* XXX check permission */ 819 sock = channel_connect_to(target, target_port); 820 xfree(target); 821 xfree(originator); 822 if (sock < 0) 823 return NULL; 824 newch = channel_new(ctype, SSH_CHANNEL_CONNECTING, 825 sock, sock, -1, CHAN_TCP_WINDOW_DEFAULT, 826 CHAN_TCP_PACKET_DEFAULT, 0, xstrdup("direct-tcpip"), 1); 827 return (newch >= 0) ? channel_lookup(newch) : NULL; 828 } 829 830 Channel * 831 server_request_session(char *ctype) 832 { 833 int newch; 834 835 debug("input_session_request"); 836 packet_done(); 837 /* 838 * A server session has no fd to read or write until a 839 * CHANNEL_REQUEST for a shell is made, so we set the type to 840 * SSH_CHANNEL_LARVAL. Additionally, a callback for handling all 841 * CHANNEL_REQUEST messages is registered. 842 */ 843 newch = channel_new(ctype, SSH_CHANNEL_LARVAL, 844 -1, -1, -1, 0, CHAN_SES_PACKET_DEFAULT, 845 0, xstrdup("server-session"), 1); 846 if (session_open(newch) == 1) { 847 channel_register_callback(newch, SSH2_MSG_CHANNEL_REQUEST, 848 session_input_channel_req, (void *)0); 849 channel_register_cleanup(newch, session_close_by_channel); 850 return channel_lookup(newch); 851 } else { 852 debug("session open failed, free channel %d", newch); 853 channel_free(newch); 854 } 855 return NULL; 856 } 857 858 void 859 server_input_channel_open(int type, int plen, void *ctxt) 860 { 861 Channel *c = NULL; 862 char *ctype; 863 u_int len; 864 int rchan; 865 int rmaxpack; 866 int rwindow; 867 868 ctype = packet_get_string(&len); 869 rchan = packet_get_int(); 870 rwindow = packet_get_int(); 871 rmaxpack = packet_get_int(); 872 873 debug("server_input_channel_open: ctype %s rchan %d win %d max %d", 874 ctype, rchan, rwindow, rmaxpack); 875 876 if (strcmp(ctype, "session") == 0) { 877 c = server_request_session(ctype); 878 } else if (strcmp(ctype, "direct-tcpip") == 0) { 879 c = server_request_direct_tcpip(ctype); 880 } 881 if (c != NULL) { 882 debug("server_input_channel_open: confirm %s", ctype); 883 c->remote_id = rchan; 884 c->remote_window = rwindow; 885 c->remote_maxpacket = rmaxpack; 886 887 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION); 888 packet_put_int(c->remote_id); 889 packet_put_int(c->self); 890 packet_put_int(c->local_window); 891 packet_put_int(c->local_maxpacket); 892 packet_send(); 893 } else { 894 debug("server_input_channel_open: failure %s", ctype); 895 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE); 896 packet_put_int(rchan); 897 packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED); 898 packet_put_cstring("bla bla"); 899 packet_put_cstring(""); 900 packet_send(); 901 } 902 xfree(ctype); 903 } 904 905 void 906 server_input_global_request(int type, int plen, void *ctxt) 907 { 908 char *rtype; 909 int want_reply; 910 int success = 0; 911 912 rtype = packet_get_string(NULL); 913 want_reply = packet_get_char(); 914 debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply); 915 916 /* -R style forwarding */ 917 if (strcmp(rtype, "tcpip-forward") == 0) { 918 struct passwd *pw; 919 char *listen_address; 920 u_short listen_port; 921 922 pw = auth_get_user(); 923 if (pw == NULL) 924 fatal("server_input_global_request: no user"); 925 listen_address = packet_get_string(NULL); /* XXX currently ignored */ 926 listen_port = (u_short)packet_get_int(); 927 debug("server_input_global_request: tcpip-forward listen %s port %d", 928 listen_address, listen_port); 929 930 /* check permissions */ 931 if (!options.allow_tcp_forwarding || 932 no_port_forwarding_flag || 933 (listen_port < IPPORT_RESERVED && pw->pw_uid != 0)) { 934 success = 0; 935 packet_send_debug("Server has disabled port forwarding."); 936 } else { 937 /* Start listening on the port */ 938 success = channel_request_forwarding( 939 listen_address, listen_port, 940 /*unspec host_to_connect*/ "<unspec host>", 941 /*unspec port_to_connect*/ 0, 942 options.gateway_ports, /*remote*/ 1); 943 } 944 xfree(listen_address); 945 } 946 if (want_reply) { 947 packet_start(success ? 948 SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE); 949 packet_send(); 950 packet_write_wait(); 951 } 952 xfree(rtype); 953 } 954 955 void 956 server_init_dispatch_20(void) 957 { 958 debug("server_init_dispatch_20"); 959 dispatch_init(&dispatch_protocol_error); 960 dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); 961 dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data); 962 dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); 963 dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); 964 dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open); 965 dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 966 dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 967 dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &channel_input_channel_request); 968 dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); 969 dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request); 970 /* client_alive */ 971 dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_channel_failure); 972 /* rekeying */ 973 dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); 974 } 975 void 976 server_init_dispatch_13(void) 977 { 978 debug("server_init_dispatch_13"); 979 dispatch_init(NULL); 980 dispatch_set(SSH_CMSG_EOF, &server_input_eof); 981 dispatch_set(SSH_CMSG_STDIN_DATA, &server_input_stdin_data); 982 dispatch_set(SSH_CMSG_WINDOW_SIZE, &server_input_window_size); 983 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close); 984 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation); 985 dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data); 986 dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 987 dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 988 dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open); 989 } 990 void 991 server_init_dispatch_15(void) 992 { 993 server_init_dispatch_13(); 994 debug("server_init_dispatch_15"); 995 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof); 996 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_oclose); 997 } 998 void 999 server_init_dispatch(void) 1000 { 1001 if (compat20) 1002 server_init_dispatch_20(); 1003 else if (compat13) 1004 server_init_dispatch_13(); 1005 else 1006 server_init_dispatch_15(); 1007 } 1008 1009