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 1.104 2002/09/19 16:03:15 stevesk Exp $"); 39 RCSID("$FreeBSD$"); 40 41 #include "xmalloc.h" 42 #include "packet.h" 43 #include "buffer.h" 44 #include "log.h" 45 #include "servconf.h" 46 #include "canohost.h" 47 #include "sshpty.h" 48 #include "channels.h" 49 #include "compat.h" 50 #include "ssh1.h" 51 #include "ssh2.h" 52 #include "auth.h" 53 #include "session.h" 54 #include "dispatch.h" 55 #include "auth-options.h" 56 #include "serverloop.h" 57 #include "misc.h" 58 #include "kex.h" 59 60 extern ServerOptions options; 61 62 /* XXX */ 63 extern Kex *xxx_kex; 64 static Authctxt *xxx_authctxt; 65 66 static Buffer stdin_buffer; /* Buffer for stdin data. */ 67 static Buffer stdout_buffer; /* Buffer for stdout data. */ 68 static Buffer stderr_buffer; /* Buffer for stderr data. */ 69 static int fdin; /* Descriptor for stdin (for writing) */ 70 static int fdout; /* Descriptor for stdout (for reading); 71 May be same number as fdin. */ 72 static int fderr; /* Descriptor for stderr. May be -1. */ 73 static long stdin_bytes = 0; /* Number of bytes written to stdin. */ 74 static long stdout_bytes = 0; /* Number of stdout bytes sent to client. */ 75 static long stderr_bytes = 0; /* Number of stderr bytes sent to client. */ 76 static long fdout_bytes = 0; /* Number of stdout bytes read from program. */ 77 static int stdin_eof = 0; /* EOF message received from client. */ 78 static int fdout_eof = 0; /* EOF encountered reading from fdout. */ 79 static int fderr_eof = 0; /* EOF encountered readung from fderr. */ 80 static int fdin_is_tty = 0; /* fdin points to a tty. */ 81 static int connection_in; /* Connection to client (input). */ 82 static int connection_out; /* Connection to client (output). */ 83 static int connection_closed = 0; /* Connection to client closed. */ 84 static u_int buffer_high; /* "Soft" max buffer size. */ 85 static int client_alive_timeouts = 0; 86 87 /* 88 * This SIGCHLD kludge is used to detect when the child exits. The server 89 * will exit after that, as soon as forwarded connections have terminated. 90 */ 91 92 static volatile sig_atomic_t child_terminated = 0; /* The child has terminated. */ 93 94 /* prototypes */ 95 static void server_init_dispatch(void); 96 97 /* 98 * we write to this pipe if a SIGCHLD is caught in order to avoid 99 * the race between select() and child_terminated 100 */ 101 static int notify_pipe[2]; 102 static void 103 notify_setup(void) 104 { 105 if (pipe(notify_pipe) < 0) { 106 error("pipe(notify_pipe) failed %s", strerror(errno)); 107 } else if ((fcntl(notify_pipe[0], F_SETFD, 1) == -1) || 108 (fcntl(notify_pipe[1], F_SETFD, 1) == -1)) { 109 error("fcntl(notify_pipe, F_SETFD) failed %s", strerror(errno)); 110 close(notify_pipe[0]); 111 close(notify_pipe[1]); 112 } else { 113 set_nonblock(notify_pipe[0]); 114 set_nonblock(notify_pipe[1]); 115 return; 116 } 117 notify_pipe[0] = -1; /* read end */ 118 notify_pipe[1] = -1; /* write end */ 119 } 120 static void 121 notify_parent(void) 122 { 123 if (notify_pipe[1] != -1) 124 write(notify_pipe[1], "", 1); 125 } 126 static void 127 notify_prepare(fd_set *readset) 128 { 129 if (notify_pipe[0] != -1) 130 FD_SET(notify_pipe[0], readset); 131 } 132 static void 133 notify_done(fd_set *readset) 134 { 135 char c; 136 137 if (notify_pipe[0] != -1 && FD_ISSET(notify_pipe[0], readset)) 138 while (read(notify_pipe[0], &c, 1) != -1) 139 debug2("notify_done: reading"); 140 } 141 142 static void 143 sigchld_handler(int sig) 144 { 145 int save_errno = errno; 146 debug("Received SIGCHLD."); 147 child_terminated = 1; 148 #ifndef _UNICOS 149 mysignal(SIGCHLD, sigchld_handler); 150 #endif 151 notify_parent(); 152 errno = save_errno; 153 } 154 155 /* 156 * Make packets from buffered stderr data, and buffer it for sending 157 * to the client. 158 */ 159 static void 160 make_packets_from_stderr_data(void) 161 { 162 int len; 163 164 /* Send buffered stderr data to the client. */ 165 while (buffer_len(&stderr_buffer) > 0 && 166 packet_not_very_much_data_to_write()) { 167 len = buffer_len(&stderr_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_STDERR_DATA); 177 packet_put_string(buffer_ptr(&stderr_buffer), len); 178 packet_send(); 179 buffer_consume(&stderr_buffer, len); 180 stderr_bytes += len; 181 } 182 } 183 184 /* 185 * Make packets from buffered stdout data, and buffer it for sending to the 186 * client. 187 */ 188 static void 189 make_packets_from_stdout_data(void) 190 { 191 int len; 192 193 /* Send buffered stdout data to the client. */ 194 while (buffer_len(&stdout_buffer) > 0 && 195 packet_not_very_much_data_to_write()) { 196 len = buffer_len(&stdout_buffer); 197 if (packet_is_interactive()) { 198 if (len > 512) 199 len = 512; 200 } else { 201 /* Keep the packets at reasonable size. */ 202 if (len > packet_get_maxsize()) 203 len = packet_get_maxsize(); 204 } 205 packet_start(SSH_SMSG_STDOUT_DATA); 206 packet_put_string(buffer_ptr(&stdout_buffer), len); 207 packet_send(); 208 buffer_consume(&stdout_buffer, len); 209 stdout_bytes += len; 210 } 211 } 212 213 static void 214 client_alive_check(void) 215 { 216 static int had_channel = 0; 217 int id; 218 219 id = channel_find_open(); 220 if (id == -1) { 221 if (!had_channel) 222 return; 223 packet_disconnect("No open channels after timeout!"); 224 } 225 had_channel = 1; 226 227 /* timeout, check to see how many we have had */ 228 if (++client_alive_timeouts > options.client_alive_count_max) 229 packet_disconnect("Timeout, your session not responding."); 230 231 /* 232 * send a bogus channel request with "wantreply", 233 * we should get back a failure 234 */ 235 channel_request_start(id, "keepalive@openssh.com", 1); 236 packet_send(); 237 } 238 239 /* 240 * Sleep in select() until we can do something. This will initialize the 241 * select masks. Upon return, the masks will indicate which descriptors 242 * have data or can accept data. Optionally, a maximum time can be specified 243 * for the duration of the wait (0 = infinite). 244 */ 245 static void 246 wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp, 247 int *nallocp, u_int max_time_milliseconds) 248 { 249 struct timeval tv, *tvp; 250 int ret; 251 int client_alive_scheduled = 0; 252 253 /* 254 * if using client_alive, set the max timeout accordingly, 255 * and indicate that this particular timeout was for client 256 * alive by setting the client_alive_scheduled flag. 257 * 258 * this could be randomized somewhat to make traffic 259 * analysis more difficult, but we're not doing it yet. 260 */ 261 if (compat20 && 262 max_time_milliseconds == 0 && options.client_alive_interval) { 263 client_alive_scheduled = 1; 264 max_time_milliseconds = options.client_alive_interval * 1000; 265 } 266 267 /* Allocate and update select() masks for channel descriptors. */ 268 channel_prepare_select(readsetp, writesetp, maxfdp, nallocp, 0); 269 270 if (compat20) { 271 #if 0 272 /* wrong: bad condition XXX */ 273 if (channel_not_very_much_buffered_data()) 274 #endif 275 FD_SET(connection_in, *readsetp); 276 } else { 277 /* 278 * Read packets from the client unless we have too much 279 * buffered stdin or channel data. 280 */ 281 if (buffer_len(&stdin_buffer) < buffer_high && 282 channel_not_very_much_buffered_data()) 283 FD_SET(connection_in, *readsetp); 284 /* 285 * If there is not too much data already buffered going to 286 * the client, try to get some more data from the program. 287 */ 288 if (packet_not_very_much_data_to_write()) { 289 if (!fdout_eof) 290 FD_SET(fdout, *readsetp); 291 if (!fderr_eof) 292 FD_SET(fderr, *readsetp); 293 } 294 /* 295 * If we have buffered data, try to write some of that data 296 * to the program. 297 */ 298 if (fdin != -1 && buffer_len(&stdin_buffer) > 0) 299 FD_SET(fdin, *writesetp); 300 } 301 notify_prepare(*readsetp); 302 303 /* 304 * If we have buffered packet data going to the client, mark that 305 * descriptor. 306 */ 307 if (packet_have_data_to_write()) 308 FD_SET(connection_out, *writesetp); 309 310 /* 311 * If child has terminated and there is enough buffer space to read 312 * from it, then read as much as is available and exit. 313 */ 314 if (child_terminated && packet_not_very_much_data_to_write()) 315 if (max_time_milliseconds == 0 || client_alive_scheduled) 316 max_time_milliseconds = 100; 317 318 if (max_time_milliseconds == 0) 319 tvp = NULL; 320 else { 321 tv.tv_sec = max_time_milliseconds / 1000; 322 tv.tv_usec = 1000 * (max_time_milliseconds % 1000); 323 tvp = &tv; 324 } 325 326 /* Wait for something to happen, or the timeout to expire. */ 327 ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp); 328 329 if (ret == -1) { 330 memset(*readsetp, 0, *nallocp); 331 memset(*writesetp, 0, *nallocp); 332 if (errno != EINTR) 333 error("select: %.100s", strerror(errno)); 334 } else if (ret == 0 && client_alive_scheduled) 335 client_alive_check(); 336 337 notify_done(*readsetp); 338 } 339 340 /* 341 * Processes input from the client and the program. Input data is stored 342 * in buffers and processed later. 343 */ 344 static void 345 process_input(fd_set * readset) 346 { 347 int len; 348 char buf[16384]; 349 350 /* Read and buffer any input data from the client. */ 351 if (FD_ISSET(connection_in, readset)) { 352 len = read(connection_in, buf, sizeof(buf)); 353 if (len == 0) { 354 verbose("Connection closed by %.100s", 355 get_remote_ipaddr()); 356 connection_closed = 1; 357 if (compat20) 358 return; 359 fatal_cleanup(); 360 } else if (len < 0) { 361 if (errno != EINTR && errno != EAGAIN) { 362 verbose("Read error from remote host " 363 "%.100s: %.100s", 364 get_remote_ipaddr(), strerror(errno)); 365 fatal_cleanup(); 366 } 367 } else { 368 /* Buffer any received data. */ 369 packet_process_incoming(buf, len); 370 } 371 } 372 if (compat20) 373 return; 374 375 /* Read and buffer any available stdout data from the program. */ 376 if (!fdout_eof && FD_ISSET(fdout, readset)) { 377 len = read(fdout, buf, sizeof(buf)); 378 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 379 /* do nothing */ 380 } else if (len <= 0) { 381 fdout_eof = 1; 382 } else { 383 buffer_append(&stdout_buffer, buf, len); 384 fdout_bytes += len; 385 } 386 } 387 /* Read and buffer any available stderr data from the program. */ 388 if (!fderr_eof && FD_ISSET(fderr, readset)) { 389 len = read(fderr, buf, sizeof(buf)); 390 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 391 /* do nothing */ 392 } else if (len <= 0) { 393 fderr_eof = 1; 394 } else { 395 buffer_append(&stderr_buffer, buf, len); 396 } 397 } 398 } 399 400 /* 401 * Sends data from internal buffers to client program stdin. 402 */ 403 static void 404 process_output(fd_set * writeset) 405 { 406 struct termios tio; 407 u_char *data; 408 u_int dlen; 409 int len; 410 411 /* Write buffered data to program stdin. */ 412 if (!compat20 && fdin != -1 && FD_ISSET(fdin, writeset)) { 413 data = buffer_ptr(&stdin_buffer); 414 dlen = buffer_len(&stdin_buffer); 415 len = write(fdin, data, dlen); 416 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 417 /* do nothing */ 418 } else if (len <= 0) { 419 if (fdin != fdout) 420 close(fdin); 421 else 422 shutdown(fdin, SHUT_WR); /* We will no longer send. */ 423 fdin = -1; 424 } else { 425 /* Successful write. */ 426 if (fdin_is_tty && dlen >= 1 && data[0] != '\r' && 427 tcgetattr(fdin, &tio) == 0 && 428 !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) { 429 /* 430 * Simulate echo to reduce the impact of 431 * traffic analysis 432 */ 433 packet_send_ignore(len); 434 packet_send(); 435 } 436 /* Consume the data from the buffer. */ 437 buffer_consume(&stdin_buffer, len); 438 /* Update the count of bytes written to the program. */ 439 stdin_bytes += len; 440 } 441 } 442 /* Send any buffered packet data to the client. */ 443 if (FD_ISSET(connection_out, writeset)) 444 packet_write_poll(); 445 } 446 447 /* 448 * Wait until all buffered output has been sent to the client. 449 * This is used when the program terminates. 450 */ 451 static void 452 drain_output(void) 453 { 454 /* Send any buffered stdout data to the client. */ 455 if (buffer_len(&stdout_buffer) > 0) { 456 packet_start(SSH_SMSG_STDOUT_DATA); 457 packet_put_string(buffer_ptr(&stdout_buffer), 458 buffer_len(&stdout_buffer)); 459 packet_send(); 460 /* Update the count of sent bytes. */ 461 stdout_bytes += buffer_len(&stdout_buffer); 462 } 463 /* Send any buffered stderr data to the client. */ 464 if (buffer_len(&stderr_buffer) > 0) { 465 packet_start(SSH_SMSG_STDERR_DATA); 466 packet_put_string(buffer_ptr(&stderr_buffer), 467 buffer_len(&stderr_buffer)); 468 packet_send(); 469 /* Update the count of sent bytes. */ 470 stderr_bytes += buffer_len(&stderr_buffer); 471 } 472 /* Wait until all buffered data has been written to the client. */ 473 packet_write_wait(); 474 } 475 476 static void 477 process_buffered_input_packets(void) 478 { 479 dispatch_run(DISPATCH_NONBLOCK, NULL, compat20 ? xxx_kex : NULL); 480 } 481 482 /* 483 * Performs the interactive session. This handles data transmission between 484 * the client and the program. Note that the notion of stdin, stdout, and 485 * stderr in this function is sort of reversed: this function writes to 486 * stdin (of the child program), and reads from stdout and stderr (of the 487 * child program). 488 */ 489 void 490 server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg) 491 { 492 fd_set *readset = NULL, *writeset = NULL; 493 int max_fd = 0, nalloc = 0; 494 int wait_status; /* Status returned by wait(). */ 495 pid_t wait_pid; /* pid returned by wait(). */ 496 int waiting_termination = 0; /* Have displayed waiting close message. */ 497 u_int max_time_milliseconds; 498 u_int previous_stdout_buffer_bytes; 499 u_int stdout_buffer_bytes; 500 int type; 501 502 debug("Entering interactive session."); 503 504 /* Initialize the SIGCHLD kludge. */ 505 child_terminated = 0; 506 mysignal(SIGCHLD, sigchld_handler); 507 508 /* Initialize our global variables. */ 509 fdin = fdin_arg; 510 fdout = fdout_arg; 511 fderr = fderr_arg; 512 513 /* nonblocking IO */ 514 set_nonblock(fdin); 515 set_nonblock(fdout); 516 /* we don't have stderr for interactive terminal sessions, see below */ 517 if (fderr != -1) 518 set_nonblock(fderr); 519 520 if (!(datafellows & SSH_BUG_IGNOREMSG) && isatty(fdin)) 521 fdin_is_tty = 1; 522 523 connection_in = packet_get_connection_in(); 524 connection_out = packet_get_connection_out(); 525 526 notify_setup(); 527 528 previous_stdout_buffer_bytes = 0; 529 530 /* Set approximate I/O buffer size. */ 531 if (packet_is_interactive()) 532 buffer_high = 4096; 533 else 534 buffer_high = 64 * 1024; 535 536 #if 0 537 /* Initialize max_fd to the maximum of the known file descriptors. */ 538 max_fd = MAX(connection_in, connection_out); 539 max_fd = MAX(max_fd, fdin); 540 max_fd = MAX(max_fd, fdout); 541 if (fderr != -1) 542 max_fd = MAX(max_fd, fderr); 543 #endif 544 545 /* Initialize Initialize buffers. */ 546 buffer_init(&stdin_buffer); 547 buffer_init(&stdout_buffer); 548 buffer_init(&stderr_buffer); 549 550 /* 551 * If we have no separate fderr (which is the case when we have a pty 552 * - there we cannot make difference between data sent to stdout and 553 * stderr), indicate that we have seen an EOF from stderr. This way 554 * we don\'t need to check the descriptor everywhere. 555 */ 556 if (fderr == -1) 557 fderr_eof = 1; 558 559 server_init_dispatch(); 560 561 /* Main loop of the server for the interactive session mode. */ 562 for (;;) { 563 564 /* Process buffered packets from the client. */ 565 process_buffered_input_packets(); 566 567 /* 568 * If we have received eof, and there is no more pending 569 * input data, cause a real eof by closing fdin. 570 */ 571 if (stdin_eof && fdin != -1 && buffer_len(&stdin_buffer) == 0) { 572 if (fdin != fdout) 573 close(fdin); 574 else 575 shutdown(fdin, SHUT_WR); /* We will no longer send. */ 576 fdin = -1; 577 } 578 /* Make packets from buffered stderr data to send to the client. */ 579 make_packets_from_stderr_data(); 580 581 /* 582 * Make packets from buffered stdout data to send to the 583 * client. If there is very little to send, this arranges to 584 * not send them now, but to wait a short while to see if we 585 * are getting more data. This is necessary, as some systems 586 * wake up readers from a pty after each separate character. 587 */ 588 max_time_milliseconds = 0; 589 stdout_buffer_bytes = buffer_len(&stdout_buffer); 590 if (stdout_buffer_bytes != 0 && stdout_buffer_bytes < 256 && 591 stdout_buffer_bytes != previous_stdout_buffer_bytes) { 592 /* try again after a while */ 593 max_time_milliseconds = 10; 594 } else { 595 /* Send it now. */ 596 make_packets_from_stdout_data(); 597 } 598 previous_stdout_buffer_bytes = buffer_len(&stdout_buffer); 599 600 /* Send channel data to the client. */ 601 if (packet_not_very_much_data_to_write()) 602 channel_output_poll(); 603 604 /* 605 * Bail out of the loop if the program has closed its output 606 * descriptors, and we have no more data to send to the 607 * client, and there is no pending buffered data. 608 */ 609 if (fdout_eof && fderr_eof && !packet_have_data_to_write() && 610 buffer_len(&stdout_buffer) == 0 && buffer_len(&stderr_buffer) == 0) { 611 if (!channel_still_open()) 612 break; 613 if (!waiting_termination) { 614 const char *s = "Waiting for forwarded connections to terminate...\r\n"; 615 char *cp; 616 waiting_termination = 1; 617 buffer_append(&stderr_buffer, s, strlen(s)); 618 619 /* Display list of open channels. */ 620 cp = channel_open_message(); 621 buffer_append(&stderr_buffer, cp, strlen(cp)); 622 xfree(cp); 623 } 624 } 625 max_fd = MAX(connection_in, connection_out); 626 max_fd = MAX(max_fd, fdin); 627 max_fd = MAX(max_fd, fdout); 628 max_fd = MAX(max_fd, fderr); 629 max_fd = MAX(max_fd, notify_pipe[0]); 630 631 /* Sleep in select() until we can do something. */ 632 wait_until_can_do_something(&readset, &writeset, &max_fd, 633 &nalloc, max_time_milliseconds); 634 635 /* Process any channel events. */ 636 channel_after_select(readset, writeset); 637 638 /* Process input from the client and from program stdout/stderr. */ 639 process_input(readset); 640 641 /* Process output to the client and to program stdin. */ 642 process_output(writeset); 643 } 644 if (readset) 645 xfree(readset); 646 if (writeset) 647 xfree(writeset); 648 649 /* Cleanup and termination code. */ 650 651 /* Wait until all output has been sent to the client. */ 652 drain_output(); 653 654 debug("End of interactive session; stdin %ld, stdout (read %ld, sent %ld), stderr %ld bytes.", 655 stdin_bytes, fdout_bytes, stdout_bytes, stderr_bytes); 656 657 /* Free and clear the buffers. */ 658 buffer_free(&stdin_buffer); 659 buffer_free(&stdout_buffer); 660 buffer_free(&stderr_buffer); 661 662 /* Close the file descriptors. */ 663 if (fdout != -1) 664 close(fdout); 665 fdout = -1; 666 fdout_eof = 1; 667 if (fderr != -1) 668 close(fderr); 669 fderr = -1; 670 fderr_eof = 1; 671 if (fdin != -1) 672 close(fdin); 673 fdin = -1; 674 675 channel_free_all(); 676 677 /* We no longer want our SIGCHLD handler to be called. */ 678 mysignal(SIGCHLD, SIG_DFL); 679 680 while ((wait_pid = waitpid(-1, &wait_status, 0)) < 0) 681 if (errno != EINTR) 682 packet_disconnect("wait: %.100s", strerror(errno)); 683 if (wait_pid != pid) 684 error("Strange, wait returned pid %ld, expected %ld", 685 (long)wait_pid, (long)pid); 686 687 /* Check if it exited normally. */ 688 if (WIFEXITED(wait_status)) { 689 /* Yes, normal exit. Get exit status and send it to the client. */ 690 debug("Command exited with status %d.", WEXITSTATUS(wait_status)); 691 packet_start(SSH_SMSG_EXITSTATUS); 692 packet_put_int(WEXITSTATUS(wait_status)); 693 packet_send(); 694 packet_write_wait(); 695 696 /* 697 * Wait for exit confirmation. Note that there might be 698 * other packets coming before it; however, the program has 699 * already died so we just ignore them. The client is 700 * supposed to respond with the confirmation when it receives 701 * the exit status. 702 */ 703 do { 704 type = packet_read(); 705 } 706 while (type != SSH_CMSG_EXIT_CONFIRMATION); 707 708 debug("Received exit confirmation."); 709 return; 710 } 711 /* Check if the program terminated due to a signal. */ 712 if (WIFSIGNALED(wait_status)) 713 packet_disconnect("Command terminated on signal %d.", 714 WTERMSIG(wait_status)); 715 716 /* Some weird exit cause. Just exit. */ 717 packet_disconnect("wait returned status %04x.", wait_status); 718 /* NOTREACHED */ 719 } 720 721 static void 722 collect_children(void) 723 { 724 pid_t pid; 725 sigset_t oset, nset; 726 int status; 727 728 /* block SIGCHLD while we check for dead children */ 729 sigemptyset(&nset); 730 sigaddset(&nset, SIGCHLD); 731 sigprocmask(SIG_BLOCK, &nset, &oset); 732 if (child_terminated) { 733 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 734 (pid < 0 && errno == EINTR)) 735 if (pid > 0) 736 session_close_by_pid(pid, status); 737 child_terminated = 0; 738 } 739 sigprocmask(SIG_SETMASK, &oset, NULL); 740 } 741 742 void 743 server_loop2(Authctxt *authctxt) 744 { 745 fd_set *readset = NULL, *writeset = NULL; 746 int rekeying = 0, max_fd, nalloc = 0; 747 748 debug("Entering interactive session for SSH2."); 749 750 mysignal(SIGCHLD, sigchld_handler); 751 child_terminated = 0; 752 connection_in = packet_get_connection_in(); 753 connection_out = packet_get_connection_out(); 754 755 notify_setup(); 756 757 max_fd = MAX(connection_in, connection_out); 758 max_fd = MAX(max_fd, notify_pipe[0]); 759 760 xxx_authctxt = authctxt; 761 762 server_init_dispatch(); 763 764 for (;;) { 765 process_buffered_input_packets(); 766 767 rekeying = (xxx_kex != NULL && !xxx_kex->done); 768 769 if (!rekeying && packet_not_very_much_data_to_write()) 770 channel_output_poll(); 771 wait_until_can_do_something(&readset, &writeset, &max_fd, 772 &nalloc, 0); 773 774 collect_children(); 775 if (!rekeying) 776 channel_after_select(readset, writeset); 777 process_input(readset); 778 if (connection_closed) 779 break; 780 process_output(writeset); 781 } 782 collect_children(); 783 784 if (readset) 785 xfree(readset); 786 if (writeset) 787 xfree(writeset); 788 789 /* free all channels, no more reads and writes */ 790 channel_free_all(); 791 792 /* free remaining sessions, e.g. remove wtmp entries */ 793 session_destroy_all(NULL); 794 } 795 796 static void 797 server_input_channel_failure(int type, u_int32_t seq, void *ctxt) 798 { 799 debug("Got CHANNEL_FAILURE for keepalive"); 800 /* 801 * reset timeout, since we got a sane answer from the client. 802 * even if this was generated by something other than 803 * the bogus CHANNEL_REQUEST we send for keepalives. 804 */ 805 client_alive_timeouts = 0; 806 } 807 808 809 static void 810 server_input_stdin_data(int type, u_int32_t seq, void *ctxt) 811 { 812 char *data; 813 u_int data_len; 814 815 /* Stdin data from the client. Append it to the buffer. */ 816 /* Ignore any data if the client has closed stdin. */ 817 if (fdin == -1) 818 return; 819 data = packet_get_string(&data_len); 820 packet_check_eom(); 821 buffer_append(&stdin_buffer, data, data_len); 822 memset(data, 0, data_len); 823 xfree(data); 824 } 825 826 static void 827 server_input_eof(int type, u_int32_t seq, void *ctxt) 828 { 829 /* 830 * Eof from the client. The stdin descriptor to the 831 * program will be closed when all buffered data has 832 * drained. 833 */ 834 debug("EOF received for stdin."); 835 packet_check_eom(); 836 stdin_eof = 1; 837 } 838 839 static void 840 server_input_window_size(int type, u_int32_t seq, void *ctxt) 841 { 842 int row = packet_get_int(); 843 int col = packet_get_int(); 844 int xpixel = packet_get_int(); 845 int ypixel = packet_get_int(); 846 847 debug("Window change received."); 848 packet_check_eom(); 849 if (fdin != -1) 850 pty_change_window_size(fdin, row, col, xpixel, ypixel); 851 } 852 853 static Channel * 854 server_request_direct_tcpip(char *ctype) 855 { 856 Channel *c; 857 int sock; 858 char *target, *originator; 859 int target_port, originator_port; 860 861 target = packet_get_string(NULL); 862 target_port = packet_get_int(); 863 originator = packet_get_string(NULL); 864 originator_port = packet_get_int(); 865 packet_check_eom(); 866 867 debug("server_request_direct_tcpip: originator %s port %d, target %s port %d", 868 originator, originator_port, target, target_port); 869 870 /* XXX check permission */ 871 sock = channel_connect_to(target, target_port); 872 xfree(target); 873 xfree(originator); 874 if (sock < 0) 875 return NULL; 876 c = channel_new(ctype, SSH_CHANNEL_CONNECTING, 877 sock, sock, -1, CHAN_TCP_WINDOW_DEFAULT, 878 CHAN_TCP_PACKET_DEFAULT, 0, xstrdup("direct-tcpip"), 1); 879 return c; 880 } 881 882 static Channel * 883 server_request_session(char *ctype) 884 { 885 Channel *c; 886 887 debug("input_session_request"); 888 packet_check_eom(); 889 /* 890 * A server session has no fd to read or write until a 891 * CHANNEL_REQUEST for a shell is made, so we set the type to 892 * SSH_CHANNEL_LARVAL. Additionally, a callback for handling all 893 * CHANNEL_REQUEST messages is registered. 894 */ 895 c = channel_new(ctype, SSH_CHANNEL_LARVAL, 896 -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT, 897 0, xstrdup("server-session"), 1); 898 if (session_open(xxx_authctxt, c->self) != 1) { 899 debug("session open failed, free channel %d", c->self); 900 channel_free(c); 901 return NULL; 902 } 903 channel_register_cleanup(c->self, session_close_by_channel); 904 return c; 905 } 906 907 static void 908 server_input_channel_open(int type, u_int32_t seq, void *ctxt) 909 { 910 Channel *c = NULL; 911 char *ctype; 912 int rchan; 913 u_int rmaxpack, rwindow, len; 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 #ifndef NO_IPPORT_RESERVED_CONCEPT 984 || (listen_port < IPPORT_RESERVED && pw->pw_uid != 0) 985 #endif 986 ) { 987 success = 0; 988 packet_send_debug("Server has disabled port forwarding."); 989 } else { 990 /* Start listening on the port */ 991 success = channel_setup_remote_fwd_listener( 992 listen_address, listen_port, options.gateway_ports); 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 static void 1005 server_input_channel_req(int type, u_int32_t seq, void *ctxt) 1006 { 1007 Channel *c; 1008 int id, reply, success = 0; 1009 char *rtype; 1010 1011 id = packet_get_int(); 1012 rtype = packet_get_string(NULL); 1013 reply = packet_get_char(); 1014 1015 debug("server_input_channel_req: channel %d request %s reply %d", 1016 id, rtype, reply); 1017 1018 if ((c = channel_lookup(id)) == NULL) 1019 packet_disconnect("server_input_channel_req: " 1020 "unknown channel %d", id); 1021 if (c->type == SSH_CHANNEL_LARVAL || c->type == SSH_CHANNEL_OPEN) 1022 success = session_input_channel_req(c, rtype); 1023 if (reply) { 1024 packet_start(success ? 1025 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE); 1026 packet_put_int(c->remote_id); 1027 packet_send(); 1028 } 1029 xfree(rtype); 1030 } 1031 1032 static void 1033 server_init_dispatch_20(void) 1034 { 1035 debug("server_init_dispatch_20"); 1036 dispatch_init(&dispatch_protocol_error); 1037 dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); 1038 dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data); 1039 dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); 1040 dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); 1041 dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open); 1042 dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 1043 dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 1044 dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req); 1045 dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); 1046 dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request); 1047 /* client_alive */ 1048 dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_channel_failure); 1049 /* rekeying */ 1050 dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); 1051 } 1052 static void 1053 server_init_dispatch_13(void) 1054 { 1055 debug("server_init_dispatch_13"); 1056 dispatch_init(NULL); 1057 dispatch_set(SSH_CMSG_EOF, &server_input_eof); 1058 dispatch_set(SSH_CMSG_STDIN_DATA, &server_input_stdin_data); 1059 dispatch_set(SSH_CMSG_WINDOW_SIZE, &server_input_window_size); 1060 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close); 1061 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation); 1062 dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data); 1063 dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 1064 dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 1065 dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open); 1066 } 1067 static void 1068 server_init_dispatch_15(void) 1069 { 1070 server_init_dispatch_13(); 1071 debug("server_init_dispatch_15"); 1072 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof); 1073 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_oclose); 1074 } 1075 static void 1076 server_init_dispatch(void) 1077 { 1078 if (compat20) 1079 server_init_dispatch_20(); 1080 else if (compat13) 1081 server_init_dispatch_13(); 1082 else 1083 server_init_dispatch_15(); 1084 } 1085