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 1.117 2004/08/11 21:43:05 avsm Exp $"); 39 40 #include "xmalloc.h" 41 #include "packet.h" 42 #include "buffer.h" 43 #include "log.h" 44 #include "servconf.h" 45 #include "canohost.h" 46 #include "sshpty.h" 47 #include "channels.h" 48 #include "compat.h" 49 #include "ssh1.h" 50 #include "ssh2.h" 51 #include "auth.h" 52 #include "session.h" 53 #include "dispatch.h" 54 #include "auth-options.h" 55 #include "serverloop.h" 56 #include "misc.h" 57 #include "kex.h" 58 59 extern ServerOptions options; 60 61 /* XXX */ 62 extern Kex *xxx_kex; 63 extern Authctxt *the_authctxt; 64 65 static Buffer stdin_buffer; /* Buffer for stdin data. */ 66 static Buffer stdout_buffer; /* Buffer for stdout data. */ 67 static Buffer stderr_buffer; /* Buffer for stderr data. */ 68 static int fdin; /* Descriptor for stdin (for writing) */ 69 static int fdout; /* Descriptor for stdout (for reading); 70 May be same number as fdin. */ 71 static int fderr; /* Descriptor for stderr. May be -1. */ 72 static long stdin_bytes = 0; /* Number of bytes written to stdin. */ 73 static long stdout_bytes = 0; /* Number of stdout bytes sent to client. */ 74 static long stderr_bytes = 0; /* Number of stderr bytes sent to client. */ 75 static long fdout_bytes = 0; /* Number of stdout bytes read from program. */ 76 static int stdin_eof = 0; /* EOF message received from client. */ 77 static int fdout_eof = 0; /* EOF encountered reading from fdout. */ 78 static int fderr_eof = 0; /* EOF encountered readung from fderr. */ 79 static int fdin_is_tty = 0; /* fdin points to a tty. */ 80 static int connection_in; /* Connection to client (input). */ 81 static int connection_out; /* Connection to client (output). */ 82 static int connection_closed = 0; /* Connection to client closed. */ 83 static u_int buffer_high; /* "Soft" max buffer size. */ 84 static int client_alive_timeouts = 0; 85 86 /* 87 * This SIGCHLD kludge is used to detect when the child exits. The server 88 * will exit after that, as soon as forwarded connections have terminated. 89 */ 90 91 static volatile sig_atomic_t child_terminated = 0; /* The child has terminated. */ 92 93 /* prototypes */ 94 static void server_init_dispatch(void); 95 96 /* 97 * we write to this pipe if a SIGCHLD is caught in order to avoid 98 * the race between select() and child_terminated 99 */ 100 static int notify_pipe[2]; 101 static void 102 notify_setup(void) 103 { 104 if (pipe(notify_pipe) < 0) { 105 error("pipe(notify_pipe) failed %s", strerror(errno)); 106 } else if ((fcntl(notify_pipe[0], F_SETFD, 1) == -1) || 107 (fcntl(notify_pipe[1], F_SETFD, 1) == -1)) { 108 error("fcntl(notify_pipe, F_SETFD) failed %s", strerror(errno)); 109 close(notify_pipe[0]); 110 close(notify_pipe[1]); 111 } else { 112 set_nonblock(notify_pipe[0]); 113 set_nonblock(notify_pipe[1]); 114 return; 115 } 116 notify_pipe[0] = -1; /* read end */ 117 notify_pipe[1] = -1; /* write end */ 118 } 119 static void 120 notify_parent(void) 121 { 122 if (notify_pipe[1] != -1) 123 write(notify_pipe[1], "", 1); 124 } 125 static void 126 notify_prepare(fd_set *readset) 127 { 128 if (notify_pipe[0] != -1) 129 FD_SET(notify_pipe[0], readset); 130 } 131 static void 132 notify_done(fd_set *readset) 133 { 134 char c; 135 136 if (notify_pipe[0] != -1 && FD_ISSET(notify_pipe[0], readset)) 137 while (read(notify_pipe[0], &c, 1) != -1) 138 debug2("notify_done: reading"); 139 } 140 141 static void 142 sigchld_handler(int sig) 143 { 144 int save_errno = errno; 145 debug("Received SIGCHLD."); 146 child_terminated = 1; 147 signal(SIGCHLD, sigchld_handler); 148 notify_parent(); 149 errno = save_errno; 150 } 151 152 /* 153 * Make packets from buffered stderr data, and buffer it for sending 154 * to the client. 155 */ 156 static void 157 make_packets_from_stderr_data(void) 158 { 159 u_int len; 160 161 /* Send buffered stderr data to the client. */ 162 while (buffer_len(&stderr_buffer) > 0 && 163 packet_not_very_much_data_to_write()) { 164 len = buffer_len(&stderr_buffer); 165 if (packet_is_interactive()) { 166 if (len > 512) 167 len = 512; 168 } else { 169 /* Keep the packets at reasonable size. */ 170 if (len > packet_get_maxsize()) 171 len = packet_get_maxsize(); 172 } 173 packet_start(SSH_SMSG_STDERR_DATA); 174 packet_put_string(buffer_ptr(&stderr_buffer), len); 175 packet_send(); 176 buffer_consume(&stderr_buffer, len); 177 stderr_bytes += len; 178 } 179 } 180 181 /* 182 * Make packets from buffered stdout data, and buffer it for sending to the 183 * client. 184 */ 185 static void 186 make_packets_from_stdout_data(void) 187 { 188 u_int len; 189 190 /* Send buffered stdout data to the client. */ 191 while (buffer_len(&stdout_buffer) > 0 && 192 packet_not_very_much_data_to_write()) { 193 len = buffer_len(&stdout_buffer); 194 if (packet_is_interactive()) { 195 if (len > 512) 196 len = 512; 197 } else { 198 /* Keep the packets at reasonable size. */ 199 if (len > packet_get_maxsize()) 200 len = packet_get_maxsize(); 201 } 202 packet_start(SSH_SMSG_STDOUT_DATA); 203 packet_put_string(buffer_ptr(&stdout_buffer), len); 204 packet_send(); 205 buffer_consume(&stdout_buffer, len); 206 stdout_bytes += len; 207 } 208 } 209 210 static void 211 client_alive_check(void) 212 { 213 int channel_id; 214 215 /* timeout, check to see how many we have had */ 216 if (++client_alive_timeouts > options.client_alive_count_max) 217 packet_disconnect("Timeout, your session not responding."); 218 219 /* 220 * send a bogus global/channel request with "wantreply", 221 * we should get back a failure 222 */ 223 if ((channel_id = channel_find_open()) == -1) { 224 packet_start(SSH2_MSG_GLOBAL_REQUEST); 225 packet_put_cstring("keepalive@openssh.com"); 226 packet_put_char(1); /* boolean: want reply */ 227 } else { 228 channel_request_start(channel_id, "keepalive@openssh.com", 1); 229 } 230 packet_send(); 231 } 232 233 /* 234 * Sleep in select() until we can do something. This will initialize the 235 * select masks. Upon return, the masks will indicate which descriptors 236 * have data or can accept data. Optionally, a maximum time can be specified 237 * for the duration of the wait (0 = infinite). 238 */ 239 static void 240 wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp, 241 u_int *nallocp, u_int max_time_milliseconds) 242 { 243 struct timeval tv, *tvp; 244 int ret; 245 int client_alive_scheduled = 0; 246 247 /* 248 * if using client_alive, set the max timeout accordingly, 249 * and indicate that this particular timeout was for client 250 * alive by setting the client_alive_scheduled flag. 251 * 252 * this could be randomized somewhat to make traffic 253 * analysis more difficult, but we're not doing it yet. 254 */ 255 if (compat20 && 256 max_time_milliseconds == 0 && options.client_alive_interval) { 257 client_alive_scheduled = 1; 258 max_time_milliseconds = options.client_alive_interval * 1000; 259 } 260 261 /* Allocate and update select() masks for channel descriptors. */ 262 channel_prepare_select(readsetp, writesetp, maxfdp, nallocp, 0); 263 264 if (compat20) { 265 #if 0 266 /* wrong: bad condition XXX */ 267 if (channel_not_very_much_buffered_data()) 268 #endif 269 FD_SET(connection_in, *readsetp); 270 } else { 271 /* 272 * Read packets from the client unless we have too much 273 * buffered stdin or channel data. 274 */ 275 if (buffer_len(&stdin_buffer) < buffer_high && 276 channel_not_very_much_buffered_data()) 277 FD_SET(connection_in, *readsetp); 278 /* 279 * If there is not too much data already buffered going to 280 * the client, try to get some more data from the program. 281 */ 282 if (packet_not_very_much_data_to_write()) { 283 if (!fdout_eof) 284 FD_SET(fdout, *readsetp); 285 if (!fderr_eof) 286 FD_SET(fderr, *readsetp); 287 } 288 /* 289 * If we have buffered data, try to write some of that data 290 * to the program. 291 */ 292 if (fdin != -1 && buffer_len(&stdin_buffer) > 0) 293 FD_SET(fdin, *writesetp); 294 } 295 notify_prepare(*readsetp); 296 297 /* 298 * If we have buffered packet data going to the client, mark that 299 * descriptor. 300 */ 301 if (packet_have_data_to_write()) 302 FD_SET(connection_out, *writesetp); 303 304 /* 305 * If child has terminated and there is enough buffer space to read 306 * from it, then read as much as is available and exit. 307 */ 308 if (child_terminated && packet_not_very_much_data_to_write()) 309 if (max_time_milliseconds == 0 || client_alive_scheduled) 310 max_time_milliseconds = 100; 311 312 if (max_time_milliseconds == 0) 313 tvp = NULL; 314 else { 315 tv.tv_sec = max_time_milliseconds / 1000; 316 tv.tv_usec = 1000 * (max_time_milliseconds % 1000); 317 tvp = &tv; 318 } 319 320 /* Wait for something to happen, or the timeout to expire. */ 321 ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp); 322 323 if (ret == -1) { 324 memset(*readsetp, 0, *nallocp); 325 memset(*writesetp, 0, *nallocp); 326 if (errno != EINTR) 327 error("select: %.100s", strerror(errno)); 328 } else if (ret == 0 && client_alive_scheduled) 329 client_alive_check(); 330 331 notify_done(*readsetp); 332 } 333 334 /* 335 * Processes input from the client and the program. Input data is stored 336 * in buffers and processed later. 337 */ 338 static void 339 process_input(fd_set * readset) 340 { 341 int len; 342 char buf[16384]; 343 344 /* Read and buffer any input data from the client. */ 345 if (FD_ISSET(connection_in, readset)) { 346 len = read(connection_in, buf, sizeof(buf)); 347 if (len == 0) { 348 verbose("Connection closed by %.100s", 349 get_remote_ipaddr()); 350 connection_closed = 1; 351 if (compat20) 352 return; 353 cleanup_exit(255); 354 } else if (len < 0) { 355 if (errno != EINTR && errno != EAGAIN) { 356 verbose("Read error from remote host " 357 "%.100s: %.100s", 358 get_remote_ipaddr(), strerror(errno)); 359 cleanup_exit(255); 360 } 361 } else { 362 /* Buffer any received data. */ 363 packet_process_incoming(buf, len); 364 } 365 } 366 if (compat20) 367 return; 368 369 /* Read and buffer any available stdout data from the program. */ 370 if (!fdout_eof && FD_ISSET(fdout, readset)) { 371 len = read(fdout, buf, sizeof(buf)); 372 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 373 /* do nothing */ 374 } else if (len <= 0) { 375 fdout_eof = 1; 376 } else { 377 buffer_append(&stdout_buffer, buf, len); 378 fdout_bytes += len; 379 } 380 } 381 /* Read and buffer any available stderr data from the program. */ 382 if (!fderr_eof && FD_ISSET(fderr, readset)) { 383 len = read(fderr, buf, sizeof(buf)); 384 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 385 /* do nothing */ 386 } else if (len <= 0) { 387 fderr_eof = 1; 388 } else { 389 buffer_append(&stderr_buffer, buf, len); 390 } 391 } 392 } 393 394 /* 395 * Sends data from internal buffers to client program stdin. 396 */ 397 static void 398 process_output(fd_set * writeset) 399 { 400 struct termios tio; 401 u_char *data; 402 u_int dlen; 403 int len; 404 405 /* Write buffered data to program stdin. */ 406 if (!compat20 && fdin != -1 && FD_ISSET(fdin, writeset)) { 407 data = buffer_ptr(&stdin_buffer); 408 dlen = buffer_len(&stdin_buffer); 409 len = write(fdin, data, dlen); 410 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 411 /* do nothing */ 412 } else if (len <= 0) { 413 if (fdin != fdout) 414 close(fdin); 415 else 416 shutdown(fdin, SHUT_WR); /* We will no longer send. */ 417 fdin = -1; 418 } else { 419 /* Successful write. */ 420 if (fdin_is_tty && dlen >= 1 && data[0] != '\r' && 421 tcgetattr(fdin, &tio) == 0 && 422 !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) { 423 /* 424 * Simulate echo to reduce the impact of 425 * traffic analysis 426 */ 427 packet_send_ignore(len); 428 packet_send(); 429 } 430 /* Consume the data from the buffer. */ 431 buffer_consume(&stdin_buffer, len); 432 /* Update the count of bytes written to the program. */ 433 stdin_bytes += len; 434 } 435 } 436 /* Send any buffered packet data to the client. */ 437 if (FD_ISSET(connection_out, writeset)) 438 packet_write_poll(); 439 } 440 441 /* 442 * Wait until all buffered output has been sent to the client. 443 * This is used when the program terminates. 444 */ 445 static void 446 drain_output(void) 447 { 448 /* Send any buffered stdout data to the client. */ 449 if (buffer_len(&stdout_buffer) > 0) { 450 packet_start(SSH_SMSG_STDOUT_DATA); 451 packet_put_string(buffer_ptr(&stdout_buffer), 452 buffer_len(&stdout_buffer)); 453 packet_send(); 454 /* Update the count of sent bytes. */ 455 stdout_bytes += buffer_len(&stdout_buffer); 456 } 457 /* Send any buffered stderr data to the client. */ 458 if (buffer_len(&stderr_buffer) > 0) { 459 packet_start(SSH_SMSG_STDERR_DATA); 460 packet_put_string(buffer_ptr(&stderr_buffer), 461 buffer_len(&stderr_buffer)); 462 packet_send(); 463 /* Update the count of sent bytes. */ 464 stderr_bytes += buffer_len(&stderr_buffer); 465 } 466 /* Wait until all buffered data has been written to the client. */ 467 packet_write_wait(); 468 } 469 470 static void 471 process_buffered_input_packets(void) 472 { 473 dispatch_run(DISPATCH_NONBLOCK, NULL, compat20 ? xxx_kex : NULL); 474 } 475 476 /* 477 * Performs the interactive session. This handles data transmission between 478 * the client and the program. Note that the notion of stdin, stdout, and 479 * stderr in this function is sort of reversed: this function writes to 480 * stdin (of the child program), and reads from stdout and stderr (of the 481 * child program). 482 */ 483 void 484 server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg) 485 { 486 fd_set *readset = NULL, *writeset = NULL; 487 int max_fd = 0; 488 u_int nalloc = 0; 489 int wait_status; /* Status returned by wait(). */ 490 pid_t wait_pid; /* pid returned by wait(). */ 491 int waiting_termination = 0; /* Have displayed waiting close message. */ 492 u_int max_time_milliseconds; 493 u_int previous_stdout_buffer_bytes; 494 u_int stdout_buffer_bytes; 495 int type; 496 497 debug("Entering interactive session."); 498 499 /* Initialize the SIGCHLD kludge. */ 500 child_terminated = 0; 501 signal(SIGCHLD, sigchld_handler); 502 503 /* Initialize our global variables. */ 504 fdin = fdin_arg; 505 fdout = fdout_arg; 506 fderr = fderr_arg; 507 508 /* nonblocking IO */ 509 set_nonblock(fdin); 510 set_nonblock(fdout); 511 /* we don't have stderr for interactive terminal sessions, see below */ 512 if (fderr != -1) 513 set_nonblock(fderr); 514 515 if (!(datafellows & SSH_BUG_IGNOREMSG) && isatty(fdin)) 516 fdin_is_tty = 1; 517 518 connection_in = packet_get_connection_in(); 519 connection_out = packet_get_connection_out(); 520 521 notify_setup(); 522 523 previous_stdout_buffer_bytes = 0; 524 525 /* Set approximate I/O buffer size. */ 526 if (packet_is_interactive()) 527 buffer_high = 4096; 528 else 529 buffer_high = 64 * 1024; 530 531 #if 0 532 /* Initialize max_fd to the maximum of the known file descriptors. */ 533 max_fd = MAX(connection_in, connection_out); 534 max_fd = MAX(max_fd, fdin); 535 max_fd = MAX(max_fd, fdout); 536 if (fderr != -1) 537 max_fd = MAX(max_fd, fderr); 538 #endif 539 540 /* Initialize Initialize buffers. */ 541 buffer_init(&stdin_buffer); 542 buffer_init(&stdout_buffer); 543 buffer_init(&stderr_buffer); 544 545 /* 546 * If we have no separate fderr (which is the case when we have a pty 547 * - there we cannot make difference between data sent to stdout and 548 * stderr), indicate that we have seen an EOF from stderr. This way 549 * we don\'t need to check the descriptor everywhere. 550 */ 551 if (fderr == -1) 552 fderr_eof = 1; 553 554 server_init_dispatch(); 555 556 /* Main loop of the server for the interactive session mode. */ 557 for (;;) { 558 559 /* Process buffered packets from the client. */ 560 process_buffered_input_packets(); 561 562 /* 563 * If we have received eof, and there is no more pending 564 * input data, cause a real eof by closing fdin. 565 */ 566 if (stdin_eof && fdin != -1 && buffer_len(&stdin_buffer) == 0) { 567 if (fdin != fdout) 568 close(fdin); 569 else 570 shutdown(fdin, SHUT_WR); /* We will no longer send. */ 571 fdin = -1; 572 } 573 /* Make packets from buffered stderr data to send to the client. */ 574 make_packets_from_stderr_data(); 575 576 /* 577 * Make packets from buffered stdout data to send to the 578 * client. If there is very little to send, this arranges to 579 * not send them now, but to wait a short while to see if we 580 * are getting more data. This is necessary, as some systems 581 * wake up readers from a pty after each separate character. 582 */ 583 max_time_milliseconds = 0; 584 stdout_buffer_bytes = buffer_len(&stdout_buffer); 585 if (stdout_buffer_bytes != 0 && stdout_buffer_bytes < 256 && 586 stdout_buffer_bytes != previous_stdout_buffer_bytes) { 587 /* try again after a while */ 588 max_time_milliseconds = 10; 589 } else { 590 /* Send it now. */ 591 make_packets_from_stdout_data(); 592 } 593 previous_stdout_buffer_bytes = buffer_len(&stdout_buffer); 594 595 /* Send channel data to the client. */ 596 if (packet_not_very_much_data_to_write()) 597 channel_output_poll(); 598 599 /* 600 * Bail out of the loop if the program has closed its output 601 * descriptors, and we have no more data to send to the 602 * client, and there is no pending buffered data. 603 */ 604 if (fdout_eof && fderr_eof && !packet_have_data_to_write() && 605 buffer_len(&stdout_buffer) == 0 && buffer_len(&stderr_buffer) == 0) { 606 if (!channel_still_open()) 607 break; 608 if (!waiting_termination) { 609 const char *s = "Waiting for forwarded connections to terminate...\r\n"; 610 char *cp; 611 waiting_termination = 1; 612 buffer_append(&stderr_buffer, s, strlen(s)); 613 614 /* Display list of open channels. */ 615 cp = channel_open_message(); 616 buffer_append(&stderr_buffer, cp, strlen(cp)); 617 xfree(cp); 618 } 619 } 620 max_fd = MAX(connection_in, connection_out); 621 max_fd = MAX(max_fd, fdin); 622 max_fd = MAX(max_fd, fdout); 623 max_fd = MAX(max_fd, fderr); 624 max_fd = MAX(max_fd, notify_pipe[0]); 625 626 /* Sleep in select() until we can do something. */ 627 wait_until_can_do_something(&readset, &writeset, &max_fd, 628 &nalloc, max_time_milliseconds); 629 630 /* Process any channel events. */ 631 channel_after_select(readset, writeset); 632 633 /* Process input from the client and from program stdout/stderr. */ 634 process_input(readset); 635 636 /* Process output to the client and to program stdin. */ 637 process_output(writeset); 638 } 639 if (readset) 640 xfree(readset); 641 if (writeset) 642 xfree(writeset); 643 644 /* Cleanup and termination code. */ 645 646 /* Wait until all output has been sent to the client. */ 647 drain_output(); 648 649 debug("End of interactive session; stdin %ld, stdout (read %ld, sent %ld), stderr %ld bytes.", 650 stdin_bytes, fdout_bytes, stdout_bytes, stderr_bytes); 651 652 /* Free and clear the buffers. */ 653 buffer_free(&stdin_buffer); 654 buffer_free(&stdout_buffer); 655 buffer_free(&stderr_buffer); 656 657 /* Close the file descriptors. */ 658 if (fdout != -1) 659 close(fdout); 660 fdout = -1; 661 fdout_eof = 1; 662 if (fderr != -1) 663 close(fderr); 664 fderr = -1; 665 fderr_eof = 1; 666 if (fdin != -1) 667 close(fdin); 668 fdin = -1; 669 670 channel_free_all(); 671 672 /* We no longer want our SIGCHLD handler to be called. */ 673 signal(SIGCHLD, SIG_DFL); 674 675 while ((wait_pid = waitpid(-1, &wait_status, 0)) < 0) 676 if (errno != EINTR) 677 packet_disconnect("wait: %.100s", strerror(errno)); 678 if (wait_pid != pid) 679 error("Strange, wait returned pid %ld, expected %ld", 680 (long)wait_pid, (long)pid); 681 682 /* Check if it exited normally. */ 683 if (WIFEXITED(wait_status)) { 684 /* Yes, normal exit. Get exit status and send it to the client. */ 685 debug("Command exited with status %d.", WEXITSTATUS(wait_status)); 686 packet_start(SSH_SMSG_EXITSTATUS); 687 packet_put_int(WEXITSTATUS(wait_status)); 688 packet_send(); 689 packet_write_wait(); 690 691 /* 692 * Wait for exit confirmation. Note that there might be 693 * other packets coming before it; however, the program has 694 * already died so we just ignore them. The client is 695 * supposed to respond with the confirmation when it receives 696 * the exit status. 697 */ 698 do { 699 type = packet_read(); 700 } 701 while (type != SSH_CMSG_EXIT_CONFIRMATION); 702 703 debug("Received exit confirmation."); 704 return; 705 } 706 /* Check if the program terminated due to a signal. */ 707 if (WIFSIGNALED(wait_status)) 708 packet_disconnect("Command terminated on signal %d.", 709 WTERMSIG(wait_status)); 710 711 /* Some weird exit cause. Just exit. */ 712 packet_disconnect("wait returned status %04x.", wait_status); 713 /* NOTREACHED */ 714 } 715 716 static void 717 collect_children(void) 718 { 719 pid_t pid; 720 sigset_t oset, nset; 721 int status; 722 723 /* block SIGCHLD while we check for dead children */ 724 sigemptyset(&nset); 725 sigaddset(&nset, SIGCHLD); 726 sigprocmask(SIG_BLOCK, &nset, &oset); 727 if (child_terminated) { 728 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 729 (pid < 0 && errno == EINTR)) 730 if (pid > 0) 731 session_close_by_pid(pid, status); 732 child_terminated = 0; 733 } 734 sigprocmask(SIG_SETMASK, &oset, NULL); 735 } 736 737 void 738 server_loop2(Authctxt *authctxt) 739 { 740 fd_set *readset = NULL, *writeset = NULL; 741 int rekeying = 0, max_fd, nalloc = 0; 742 743 debug("Entering interactive session for SSH2."); 744 745 signal(SIGCHLD, sigchld_handler); 746 child_terminated = 0; 747 connection_in = packet_get_connection_in(); 748 connection_out = packet_get_connection_out(); 749 750 notify_setup(); 751 752 max_fd = MAX(connection_in, connection_out); 753 max_fd = MAX(max_fd, notify_pipe[0]); 754 755 server_init_dispatch(); 756 757 for (;;) { 758 process_buffered_input_packets(); 759 760 rekeying = (xxx_kex != NULL && !xxx_kex->done); 761 762 if (!rekeying && packet_not_very_much_data_to_write()) 763 channel_output_poll(); 764 wait_until_can_do_something(&readset, &writeset, &max_fd, 765 &nalloc, 0); 766 767 collect_children(); 768 if (!rekeying) { 769 channel_after_select(readset, writeset); 770 if (packet_need_rekeying()) { 771 debug("need rekeying"); 772 xxx_kex->done = 0; 773 kex_send_kexinit(xxx_kex); 774 } 775 } 776 process_input(readset); 777 if (connection_closed) 778 break; 779 process_output(writeset); 780 } 781 collect_children(); 782 783 if (readset) 784 xfree(readset); 785 if (writeset) 786 xfree(writeset); 787 788 /* free all channels, no more reads and writes */ 789 channel_free_all(); 790 791 /* free remaining sessions, e.g. remove wtmp entries */ 792 session_destroy_all(NULL); 793 } 794 795 static void 796 server_input_keep_alive(int type, u_int32_t seq, void *ctxt) 797 { 798 debug("Got %d/%u for keepalive", type, seq); 799 /* 800 * reset timeout, since we got a sane answer from the client. 801 * even if this was generated by something other than 802 * the bogus CHANNEL_REQUEST we send for keepalives. 803 */ 804 client_alive_timeouts = 0; 805 } 806 807 static void 808 server_input_stdin_data(int type, u_int32_t seq, void *ctxt) 809 { 810 char *data; 811 u_int data_len; 812 813 /* Stdin data from the client. Append it to the buffer. */ 814 /* Ignore any data if the client has closed stdin. */ 815 if (fdin == -1) 816 return; 817 data = packet_get_string(&data_len); 818 packet_check_eom(); 819 buffer_append(&stdin_buffer, data, data_len); 820 memset(data, 0, data_len); 821 xfree(data); 822 } 823 824 static void 825 server_input_eof(int type, u_int32_t seq, void *ctxt) 826 { 827 /* 828 * Eof from the client. The stdin descriptor to the 829 * program will be closed when all buffered data has 830 * drained. 831 */ 832 debug("EOF received for stdin."); 833 packet_check_eom(); 834 stdin_eof = 1; 835 } 836 837 static void 838 server_input_window_size(int type, u_int32_t seq, void *ctxt) 839 { 840 int row = packet_get_int(); 841 int col = packet_get_int(); 842 int xpixel = packet_get_int(); 843 int ypixel = packet_get_int(); 844 845 debug("Window change received."); 846 packet_check_eom(); 847 if (fdin != -1) 848 pty_change_window_size(fdin, row, col, xpixel, ypixel); 849 } 850 851 static Channel * 852 server_request_direct_tcpip(void) 853 { 854 Channel *c; 855 int sock; 856 char *target, *originator; 857 int target_port, originator_port; 858 859 target = packet_get_string(NULL); 860 target_port = packet_get_int(); 861 originator = packet_get_string(NULL); 862 originator_port = packet_get_int(); 863 packet_check_eom(); 864 865 debug("server_request_direct_tcpip: originator %s port %d, target %s port %d", 866 originator, originator_port, target, target_port); 867 868 /* XXX check permission */ 869 sock = channel_connect_to(target, target_port); 870 xfree(target); 871 xfree(originator); 872 if (sock < 0) 873 return NULL; 874 c = channel_new("direct-tcpip", SSH_CHANNEL_CONNECTING, 875 sock, sock, -1, CHAN_TCP_WINDOW_DEFAULT, 876 CHAN_TCP_PACKET_DEFAULT, 0, "direct-tcpip", 1); 877 return c; 878 } 879 880 static Channel * 881 server_request_session(void) 882 { 883 Channel *c; 884 885 debug("input_session_request"); 886 packet_check_eom(); 887 /* 888 * A server session has no fd to read or write until a 889 * CHANNEL_REQUEST for a shell is made, so we set the type to 890 * SSH_CHANNEL_LARVAL. Additionally, a callback for handling all 891 * CHANNEL_REQUEST messages is registered. 892 */ 893 c = channel_new("session", SSH_CHANNEL_LARVAL, 894 -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT, 895 0, "server-session", 1); 896 if (session_open(the_authctxt, c->self) != 1) { 897 debug("session open failed, free channel %d", c->self); 898 channel_free(c); 899 return NULL; 900 } 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 int rchan; 911 u_int rmaxpack, rwindow, len; 912 913 ctype = packet_get_string(&len); 914 rchan = packet_get_int(); 915 rwindow = packet_get_int(); 916 rmaxpack = packet_get_int(); 917 918 debug("server_input_channel_open: ctype %s rchan %d win %d max %d", 919 ctype, rchan, rwindow, rmaxpack); 920 921 if (strcmp(ctype, "session") == 0) { 922 c = server_request_session(); 923 } else if (strcmp(ctype, "direct-tcpip") == 0) { 924 c = server_request_direct_tcpip(); 925 } 926 if (c != NULL) { 927 debug("server_input_channel_open: confirm %s", ctype); 928 c->remote_id = rchan; 929 c->remote_window = rwindow; 930 c->remote_maxpacket = rmaxpack; 931 if (c->type != SSH_CHANNEL_CONNECTING) { 932 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION); 933 packet_put_int(c->remote_id); 934 packet_put_int(c->self); 935 packet_put_int(c->local_window); 936 packet_put_int(c->local_maxpacket); 937 packet_send(); 938 } 939 } else { 940 debug("server_input_channel_open: failure %s", ctype); 941 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE); 942 packet_put_int(rchan); 943 packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED); 944 if (!(datafellows & SSH_BUG_OPENFAILURE)) { 945 packet_put_cstring("open failed"); 946 packet_put_cstring(""); 947 } 948 packet_send(); 949 } 950 xfree(ctype); 951 } 952 953 static void 954 server_input_global_request(int type, u_int32_t seq, void *ctxt) 955 { 956 char *rtype; 957 int want_reply; 958 int success = 0; 959 960 rtype = packet_get_string(NULL); 961 want_reply = packet_get_char(); 962 debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply); 963 964 /* -R style forwarding */ 965 if (strcmp(rtype, "tcpip-forward") == 0) { 966 struct passwd *pw; 967 char *listen_address; 968 u_short listen_port; 969 970 pw = the_authctxt->pw; 971 if (pw == NULL || !the_authctxt->valid) 972 fatal("server_input_global_request: no/invalid user"); 973 listen_address = packet_get_string(NULL); 974 listen_port = (u_short)packet_get_int(); 975 debug("server_input_global_request: tcpip-forward listen %s port %d", 976 listen_address, listen_port); 977 978 /* check permissions */ 979 if (!options.allow_tcp_forwarding || 980 no_port_forwarding_flag || 981 (listen_port < IPPORT_RESERVED && pw->pw_uid != 0)) { 982 success = 0; 983 packet_send_debug("Server has disabled port forwarding."); 984 } else { 985 /* Start listening on the port */ 986 success = channel_setup_remote_fwd_listener( 987 listen_address, listen_port, options.gateway_ports); 988 } 989 xfree(listen_address); 990 } else if (strcmp(rtype, "cancel-tcpip-forward") == 0) { 991 char *cancel_address; 992 u_short cancel_port; 993 994 cancel_address = packet_get_string(NULL); 995 cancel_port = (u_short)packet_get_int(); 996 debug("%s: cancel-tcpip-forward addr %s port %d", __func__, 997 cancel_address, cancel_port); 998 999 success = channel_cancel_rport_listener(cancel_address, 1000 cancel_port); 1001 } 1002 if (want_reply) { 1003 packet_start(success ? 1004 SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE); 1005 packet_send(); 1006 packet_write_wait(); 1007 } 1008 xfree(rtype); 1009 } 1010 static void 1011 server_input_channel_req(int type, u_int32_t seq, void *ctxt) 1012 { 1013 Channel *c; 1014 int id, reply, success = 0; 1015 char *rtype; 1016 1017 id = packet_get_int(); 1018 rtype = packet_get_string(NULL); 1019 reply = packet_get_char(); 1020 1021 debug("server_input_channel_req: channel %d request %s reply %d", 1022 id, rtype, reply); 1023 1024 if ((c = channel_lookup(id)) == NULL) 1025 packet_disconnect("server_input_channel_req: " 1026 "unknown channel %d", id); 1027 if (c->type == SSH_CHANNEL_LARVAL || c->type == SSH_CHANNEL_OPEN) 1028 success = session_input_channel_req(c, rtype); 1029 if (reply) { 1030 packet_start(success ? 1031 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE); 1032 packet_put_int(c->remote_id); 1033 packet_send(); 1034 } 1035 xfree(rtype); 1036 } 1037 1038 static void 1039 server_init_dispatch_20(void) 1040 { 1041 debug("server_init_dispatch_20"); 1042 dispatch_init(&dispatch_protocol_error); 1043 dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); 1044 dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data); 1045 dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); 1046 dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); 1047 dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open); 1048 dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 1049 dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 1050 dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req); 1051 dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); 1052 dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request); 1053 /* client_alive */ 1054 dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_keep_alive); 1055 dispatch_set(SSH2_MSG_REQUEST_SUCCESS, &server_input_keep_alive); 1056 dispatch_set(SSH2_MSG_REQUEST_FAILURE, &server_input_keep_alive); 1057 /* rekeying */ 1058 dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); 1059 } 1060 static void 1061 server_init_dispatch_13(void) 1062 { 1063 debug("server_init_dispatch_13"); 1064 dispatch_init(NULL); 1065 dispatch_set(SSH_CMSG_EOF, &server_input_eof); 1066 dispatch_set(SSH_CMSG_STDIN_DATA, &server_input_stdin_data); 1067 dispatch_set(SSH_CMSG_WINDOW_SIZE, &server_input_window_size); 1068 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close); 1069 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation); 1070 dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data); 1071 dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 1072 dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 1073 dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open); 1074 } 1075 static void 1076 server_init_dispatch_15(void) 1077 { 1078 server_init_dispatch_13(); 1079 debug("server_init_dispatch_15"); 1080 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof); 1081 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_oclose); 1082 } 1083 static void 1084 server_init_dispatch(void) 1085 { 1086 if (compat20) 1087 server_init_dispatch_20(); 1088 else if (compat13) 1089 server_init_dispatch_13(); 1090 else 1091 server_init_dispatch_15(); 1092 } 1093