1 /* $OpenBSD: serverloop.c,v 1.144 2006/08/03 03:34:42 deraadt Exp $ */ 2 /* 3 * Author: Tatu Ylonen <ylo@cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 5 * All rights reserved 6 * Server main loop for handling the interactive session. 7 * 8 * As far as I am concerned, the code I have written for this software 9 * can be used freely for any purpose. Any derived versions of this 10 * software must be clearly marked as such, and if the derived work is 11 * incompatible with the protocol description in the RFC file, it must be 12 * called by a name other than "ssh" or "Secure Shell". 13 * 14 * SSH2 support by Markus Friedl. 15 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 16 * 17 * Redistribution and use in source and binary forms, with or without 18 * modification, are permitted provided that the following conditions 19 * are met: 20 * 1. Redistributions of source code must retain the above copyright 21 * notice, this list of conditions and the following disclaimer. 22 * 2. Redistributions in binary form must reproduce the above copyright 23 * notice, this list of conditions and the following disclaimer in the 24 * documentation and/or other materials provided with the distribution. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 27 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 28 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 29 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 30 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 31 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 32 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 33 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 34 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 35 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 36 */ 37 38 #include <sys/types.h> 39 #include <sys/wait.h> 40 #include <sys/socket.h> 41 #include <sys/time.h> 42 #include <sys/param.h> 43 44 #include <netinet/in.h> 45 46 #include <errno.h> 47 #include <fcntl.h> 48 #include <pwd.h> 49 #include <signal.h> 50 #include <string.h> 51 #include <termios.h> 52 #include <unistd.h> 53 #include <stdarg.h> 54 55 #include "xmalloc.h" 56 #include "packet.h" 57 #include "buffer.h" 58 #include "log.h" 59 #include "servconf.h" 60 #include "canohost.h" 61 #include "sshpty.h" 62 #include "channels.h" 63 #include "compat.h" 64 #include "ssh1.h" 65 #include "ssh2.h" 66 #include "key.h" 67 #include "cipher.h" 68 #include "kex.h" 69 #include "hostfile.h" 70 #include "auth.h" 71 #include "session.h" 72 #include "dispatch.h" 73 #include "auth-options.h" 74 #include "serverloop.h" 75 #include "misc.h" 76 77 extern ServerOptions options; 78 79 /* XXX */ 80 extern Kex *xxx_kex; 81 extern Authctxt *the_authctxt; 82 extern int use_privsep; 83 84 static Buffer stdin_buffer; /* Buffer for stdin data. */ 85 static Buffer stdout_buffer; /* Buffer for stdout data. */ 86 static Buffer stderr_buffer; /* Buffer for stderr data. */ 87 static int fdin; /* Descriptor for stdin (for writing) */ 88 static int fdout; /* Descriptor for stdout (for reading); 89 May be same number as fdin. */ 90 static int fderr; /* Descriptor for stderr. May be -1. */ 91 static long stdin_bytes = 0; /* Number of bytes written to stdin. */ 92 static long stdout_bytes = 0; /* Number of stdout bytes sent to client. */ 93 static long stderr_bytes = 0; /* Number of stderr bytes sent to client. */ 94 static long fdout_bytes = 0; /* Number of stdout bytes read from program. */ 95 static int stdin_eof = 0; /* EOF message received from client. */ 96 static int fdout_eof = 0; /* EOF encountered reading from fdout. */ 97 static int fderr_eof = 0; /* EOF encountered readung from fderr. */ 98 static int fdin_is_tty = 0; /* fdin points to a tty. */ 99 static int connection_in; /* Connection to client (input). */ 100 static int connection_out; /* Connection to client (output). */ 101 static int connection_closed = 0; /* Connection to client closed. */ 102 static u_int buffer_high; /* "Soft" max buffer size. */ 103 static int client_alive_timeouts = 0; 104 105 /* 106 * This SIGCHLD kludge is used to detect when the child exits. The server 107 * will exit after that, as soon as forwarded connections have terminated. 108 */ 109 110 static volatile sig_atomic_t child_terminated = 0; /* The child has terminated. */ 111 112 /* Cleanup on signals (!use_privsep case only) */ 113 static volatile sig_atomic_t received_sigterm = 0; 114 115 /* prototypes */ 116 static void server_init_dispatch(void); 117 118 /* 119 * we write to this pipe if a SIGCHLD is caught in order to avoid 120 * the race between select() and child_terminated 121 */ 122 static int notify_pipe[2]; 123 static void 124 notify_setup(void) 125 { 126 if (pipe(notify_pipe) < 0) { 127 error("pipe(notify_pipe) failed %s", strerror(errno)); 128 } else if ((fcntl(notify_pipe[0], F_SETFD, 1) == -1) || 129 (fcntl(notify_pipe[1], F_SETFD, 1) == -1)) { 130 error("fcntl(notify_pipe, F_SETFD) failed %s", strerror(errno)); 131 close(notify_pipe[0]); 132 close(notify_pipe[1]); 133 } else { 134 set_nonblock(notify_pipe[0]); 135 set_nonblock(notify_pipe[1]); 136 return; 137 } 138 notify_pipe[0] = -1; /* read end */ 139 notify_pipe[1] = -1; /* write end */ 140 } 141 static void 142 notify_parent(void) 143 { 144 if (notify_pipe[1] != -1) 145 write(notify_pipe[1], "", 1); 146 } 147 static void 148 notify_prepare(fd_set *readset) 149 { 150 if (notify_pipe[0] != -1) 151 FD_SET(notify_pipe[0], readset); 152 } 153 static void 154 notify_done(fd_set *readset) 155 { 156 char c; 157 158 if (notify_pipe[0] != -1 && FD_ISSET(notify_pipe[0], readset)) 159 while (read(notify_pipe[0], &c, 1) != -1) 160 debug2("notify_done: reading"); 161 } 162 163 /*ARGSUSED*/ 164 static void 165 sigchld_handler(int sig) 166 { 167 int save_errno = errno; 168 child_terminated = 1; 169 signal(SIGCHLD, sigchld_handler); 170 notify_parent(); 171 errno = save_errno; 172 } 173 174 /*ARGSUSED*/ 175 static void 176 sigterm_handler(int sig) 177 { 178 received_sigterm = sig; 179 } 180 181 /* 182 * Make packets from buffered stderr data, and buffer it for sending 183 * to the client. 184 */ 185 static void 186 make_packets_from_stderr_data(void) 187 { 188 u_int len; 189 190 /* Send buffered stderr data to the client. */ 191 while (buffer_len(&stderr_buffer) > 0 && 192 packet_not_very_much_data_to_write()) { 193 len = buffer_len(&stderr_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_STDERR_DATA); 203 packet_put_string(buffer_ptr(&stderr_buffer), len); 204 packet_send(); 205 buffer_consume(&stderr_buffer, len); 206 stderr_bytes += len; 207 } 208 } 209 210 /* 211 * Make packets from buffered stdout data, and buffer it for sending to the 212 * client. 213 */ 214 static void 215 make_packets_from_stdout_data(void) 216 { 217 u_int len; 218 219 /* Send buffered stdout data to the client. */ 220 while (buffer_len(&stdout_buffer) > 0 && 221 packet_not_very_much_data_to_write()) { 222 len = buffer_len(&stdout_buffer); 223 if (packet_is_interactive()) { 224 if (len > 512) 225 len = 512; 226 } else { 227 /* Keep the packets at reasonable size. */ 228 if (len > packet_get_maxsize()) 229 len = packet_get_maxsize(); 230 } 231 packet_start(SSH_SMSG_STDOUT_DATA); 232 packet_put_string(buffer_ptr(&stdout_buffer), len); 233 packet_send(); 234 buffer_consume(&stdout_buffer, len); 235 stdout_bytes += len; 236 } 237 } 238 239 static void 240 client_alive_check(void) 241 { 242 int channel_id; 243 244 /* timeout, check to see how many we have had */ 245 if (++client_alive_timeouts > options.client_alive_count_max) 246 packet_disconnect("Timeout, your session not responding."); 247 248 /* 249 * send a bogus global/channel request with "wantreply", 250 * we should get back a failure 251 */ 252 if ((channel_id = channel_find_open()) == -1) { 253 packet_start(SSH2_MSG_GLOBAL_REQUEST); 254 packet_put_cstring("keepalive@openssh.com"); 255 packet_put_char(1); /* boolean: want reply */ 256 } else { 257 channel_request_start(channel_id, "keepalive@openssh.com", 1); 258 } 259 packet_send(); 260 } 261 262 /* 263 * Sleep in select() until we can do something. This will initialize the 264 * select masks. Upon return, the masks will indicate which descriptors 265 * have data or can accept data. Optionally, a maximum time can be specified 266 * for the duration of the wait (0 = infinite). 267 */ 268 static void 269 wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp, 270 u_int *nallocp, u_int max_time_milliseconds) 271 { 272 struct timeval tv, *tvp; 273 int ret; 274 int client_alive_scheduled = 0; 275 276 /* 277 * if using client_alive, set the max timeout accordingly, 278 * and indicate that this particular timeout was for client 279 * alive by setting the client_alive_scheduled flag. 280 * 281 * this could be randomized somewhat to make traffic 282 * analysis more difficult, but we're not doing it yet. 283 */ 284 if (compat20 && 285 max_time_milliseconds == 0 && options.client_alive_interval) { 286 client_alive_scheduled = 1; 287 max_time_milliseconds = options.client_alive_interval * 1000; 288 } 289 290 /* Allocate and update select() masks for channel descriptors. */ 291 channel_prepare_select(readsetp, writesetp, maxfdp, nallocp, 0); 292 293 if (compat20) { 294 #if 0 295 /* wrong: bad condition XXX */ 296 if (channel_not_very_much_buffered_data()) 297 #endif 298 FD_SET(connection_in, *readsetp); 299 } else { 300 /* 301 * Read packets from the client unless we have too much 302 * buffered stdin or channel data. 303 */ 304 if (buffer_len(&stdin_buffer) < buffer_high && 305 channel_not_very_much_buffered_data()) 306 FD_SET(connection_in, *readsetp); 307 /* 308 * If there is not too much data already buffered going to 309 * the client, try to get some more data from the program. 310 */ 311 if (packet_not_very_much_data_to_write()) { 312 if (!fdout_eof) 313 FD_SET(fdout, *readsetp); 314 if (!fderr_eof) 315 FD_SET(fderr, *readsetp); 316 } 317 /* 318 * If we have buffered data, try to write some of that data 319 * to the program. 320 */ 321 if (fdin != -1 && buffer_len(&stdin_buffer) > 0) 322 FD_SET(fdin, *writesetp); 323 } 324 notify_prepare(*readsetp); 325 326 /* 327 * If we have buffered packet data going to the client, mark that 328 * descriptor. 329 */ 330 if (packet_have_data_to_write()) 331 FD_SET(connection_out, *writesetp); 332 333 /* 334 * If child has terminated and there is enough buffer space to read 335 * from it, then read as much as is available and exit. 336 */ 337 if (child_terminated && packet_not_very_much_data_to_write()) 338 if (max_time_milliseconds == 0 || client_alive_scheduled) 339 max_time_milliseconds = 100; 340 341 if (max_time_milliseconds == 0) 342 tvp = NULL; 343 else { 344 tv.tv_sec = max_time_milliseconds / 1000; 345 tv.tv_usec = 1000 * (max_time_milliseconds % 1000); 346 tvp = &tv; 347 } 348 349 /* Wait for something to happen, or the timeout to expire. */ 350 ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp); 351 352 if (ret == -1) { 353 memset(*readsetp, 0, *nallocp); 354 memset(*writesetp, 0, *nallocp); 355 if (errno != EINTR) 356 error("select: %.100s", strerror(errno)); 357 } else if (ret == 0 && client_alive_scheduled) 358 client_alive_check(); 359 360 notify_done(*readsetp); 361 } 362 363 /* 364 * Processes input from the client and the program. Input data is stored 365 * in buffers and processed later. 366 */ 367 static void 368 process_input(fd_set *readset) 369 { 370 int len; 371 char buf[16384]; 372 373 /* Read and buffer any input data from the client. */ 374 if (FD_ISSET(connection_in, readset)) { 375 len = read(connection_in, buf, sizeof(buf)); 376 if (len == 0) { 377 verbose("Connection closed by %.100s", 378 get_remote_ipaddr()); 379 connection_closed = 1; 380 if (compat20) 381 return; 382 cleanup_exit(255); 383 } else if (len < 0) { 384 if (errno != EINTR && errno != EAGAIN) { 385 verbose("Read error from remote host " 386 "%.100s: %.100s", 387 get_remote_ipaddr(), strerror(errno)); 388 cleanup_exit(255); 389 } 390 } else { 391 /* Buffer any received data. */ 392 packet_process_incoming(buf, len); 393 } 394 } 395 if (compat20) 396 return; 397 398 /* Read and buffer any available stdout data from the program. */ 399 if (!fdout_eof && FD_ISSET(fdout, readset)) { 400 len = read(fdout, buf, sizeof(buf)); 401 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 402 /* do nothing */ 403 } else if (len <= 0) { 404 fdout_eof = 1; 405 } else { 406 buffer_append(&stdout_buffer, buf, len); 407 fdout_bytes += len; 408 } 409 } 410 /* Read and buffer any available stderr data from the program. */ 411 if (!fderr_eof && FD_ISSET(fderr, readset)) { 412 len = read(fderr, buf, sizeof(buf)); 413 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 414 /* do nothing */ 415 } else if (len <= 0) { 416 fderr_eof = 1; 417 } else { 418 buffer_append(&stderr_buffer, buf, len); 419 } 420 } 421 } 422 423 /* 424 * Sends data from internal buffers to client program stdin. 425 */ 426 static void 427 process_output(fd_set *writeset) 428 { 429 struct termios tio; 430 u_char *data; 431 u_int dlen; 432 int len; 433 434 /* Write buffered data to program stdin. */ 435 if (!compat20 && fdin != -1 && FD_ISSET(fdin, writeset)) { 436 data = buffer_ptr(&stdin_buffer); 437 dlen = buffer_len(&stdin_buffer); 438 len = write(fdin, data, dlen); 439 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 440 /* do nothing */ 441 } else if (len <= 0) { 442 if (fdin != fdout) 443 close(fdin); 444 else 445 shutdown(fdin, SHUT_WR); /* We will no longer send. */ 446 fdin = -1; 447 } else { 448 /* Successful write. */ 449 if (fdin_is_tty && dlen >= 1 && data[0] != '\r' && 450 tcgetattr(fdin, &tio) == 0 && 451 !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) { 452 /* 453 * Simulate echo to reduce the impact of 454 * traffic analysis 455 */ 456 packet_send_ignore(len); 457 packet_send(); 458 } 459 /* Consume the data from the buffer. */ 460 buffer_consume(&stdin_buffer, len); 461 /* Update the count of bytes written to the program. */ 462 stdin_bytes += len; 463 } 464 } 465 /* Send any buffered packet data to the client. */ 466 if (FD_ISSET(connection_out, writeset)) 467 packet_write_poll(); 468 } 469 470 /* 471 * Wait until all buffered output has been sent to the client. 472 * This is used when the program terminates. 473 */ 474 static void 475 drain_output(void) 476 { 477 /* Send any buffered stdout data to the client. */ 478 if (buffer_len(&stdout_buffer) > 0) { 479 packet_start(SSH_SMSG_STDOUT_DATA); 480 packet_put_string(buffer_ptr(&stdout_buffer), 481 buffer_len(&stdout_buffer)); 482 packet_send(); 483 /* Update the count of sent bytes. */ 484 stdout_bytes += buffer_len(&stdout_buffer); 485 } 486 /* Send any buffered stderr data to the client. */ 487 if (buffer_len(&stderr_buffer) > 0) { 488 packet_start(SSH_SMSG_STDERR_DATA); 489 packet_put_string(buffer_ptr(&stderr_buffer), 490 buffer_len(&stderr_buffer)); 491 packet_send(); 492 /* Update the count of sent bytes. */ 493 stderr_bytes += buffer_len(&stderr_buffer); 494 } 495 /* Wait until all buffered data has been written to the client. */ 496 packet_write_wait(); 497 } 498 499 static void 500 process_buffered_input_packets(void) 501 { 502 dispatch_run(DISPATCH_NONBLOCK, NULL, compat20 ? xxx_kex : NULL); 503 } 504 505 /* 506 * Performs the interactive session. This handles data transmission between 507 * the client and the program. Note that the notion of stdin, stdout, and 508 * stderr in this function is sort of reversed: this function writes to 509 * stdin (of the child program), and reads from stdout and stderr (of the 510 * child program). 511 */ 512 void 513 server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg) 514 { 515 fd_set *readset = NULL, *writeset = NULL; 516 int max_fd = 0; 517 u_int nalloc = 0; 518 int wait_status; /* Status returned by wait(). */ 519 pid_t wait_pid; /* pid returned by wait(). */ 520 int waiting_termination = 0; /* Have displayed waiting close message. */ 521 u_int max_time_milliseconds; 522 u_int previous_stdout_buffer_bytes; 523 u_int stdout_buffer_bytes; 524 int type; 525 526 debug("Entering interactive session."); 527 528 /* Initialize the SIGCHLD kludge. */ 529 child_terminated = 0; 530 signal(SIGCHLD, sigchld_handler); 531 532 if (!use_privsep) { 533 signal(SIGTERM, sigterm_handler); 534 signal(SIGINT, sigterm_handler); 535 signal(SIGQUIT, sigterm_handler); 536 } 537 538 /* Initialize our global variables. */ 539 fdin = fdin_arg; 540 fdout = fdout_arg; 541 fderr = fderr_arg; 542 543 /* nonblocking IO */ 544 set_nonblock(fdin); 545 set_nonblock(fdout); 546 /* we don't have stderr for interactive terminal sessions, see below */ 547 if (fderr != -1) 548 set_nonblock(fderr); 549 550 if (!(datafellows & SSH_BUG_IGNOREMSG) && isatty(fdin)) 551 fdin_is_tty = 1; 552 553 connection_in = packet_get_connection_in(); 554 connection_out = packet_get_connection_out(); 555 556 notify_setup(); 557 558 previous_stdout_buffer_bytes = 0; 559 560 /* Set approximate I/O buffer size. */ 561 if (packet_is_interactive()) 562 buffer_high = 4096; 563 else 564 buffer_high = 64 * 1024; 565 566 #if 0 567 /* Initialize max_fd to the maximum of the known file descriptors. */ 568 max_fd = MAX(connection_in, connection_out); 569 max_fd = MAX(max_fd, fdin); 570 max_fd = MAX(max_fd, fdout); 571 if (fderr != -1) 572 max_fd = MAX(max_fd, fderr); 573 #endif 574 575 /* Initialize Initialize buffers. */ 576 buffer_init(&stdin_buffer); 577 buffer_init(&stdout_buffer); 578 buffer_init(&stderr_buffer); 579 580 /* 581 * If we have no separate fderr (which is the case when we have a pty 582 * - there we cannot make difference between data sent to stdout and 583 * stderr), indicate that we have seen an EOF from stderr. This way 584 * we don't need to check the descriptor everywhere. 585 */ 586 if (fderr == -1) 587 fderr_eof = 1; 588 589 server_init_dispatch(); 590 591 /* Main loop of the server for the interactive session mode. */ 592 for (;;) { 593 594 /* Process buffered packets from the client. */ 595 process_buffered_input_packets(); 596 597 /* 598 * If we have received eof, and there is no more pending 599 * input data, cause a real eof by closing fdin. 600 */ 601 if (stdin_eof && fdin != -1 && buffer_len(&stdin_buffer) == 0) { 602 if (fdin != fdout) 603 close(fdin); 604 else 605 shutdown(fdin, SHUT_WR); /* We will no longer send. */ 606 fdin = -1; 607 } 608 /* Make packets from buffered stderr data to send to the client. */ 609 make_packets_from_stderr_data(); 610 611 /* 612 * Make packets from buffered stdout data to send to the 613 * client. If there is very little to send, this arranges to 614 * not send them now, but to wait a short while to see if we 615 * are getting more data. This is necessary, as some systems 616 * wake up readers from a pty after each separate character. 617 */ 618 max_time_milliseconds = 0; 619 stdout_buffer_bytes = buffer_len(&stdout_buffer); 620 if (stdout_buffer_bytes != 0 && stdout_buffer_bytes < 256 && 621 stdout_buffer_bytes != previous_stdout_buffer_bytes) { 622 /* try again after a while */ 623 max_time_milliseconds = 10; 624 } else { 625 /* Send it now. */ 626 make_packets_from_stdout_data(); 627 } 628 previous_stdout_buffer_bytes = buffer_len(&stdout_buffer); 629 630 /* Send channel data to the client. */ 631 if (packet_not_very_much_data_to_write()) 632 channel_output_poll(); 633 634 /* 635 * Bail out of the loop if the program has closed its output 636 * descriptors, and we have no more data to send to the 637 * client, and there is no pending buffered data. 638 */ 639 if (fdout_eof && fderr_eof && !packet_have_data_to_write() && 640 buffer_len(&stdout_buffer) == 0 && buffer_len(&stderr_buffer) == 0) { 641 if (!channel_still_open()) 642 break; 643 if (!waiting_termination) { 644 const char *s = "Waiting for forwarded connections to terminate...\r\n"; 645 char *cp; 646 waiting_termination = 1; 647 buffer_append(&stderr_buffer, s, strlen(s)); 648 649 /* Display list of open channels. */ 650 cp = channel_open_message(); 651 buffer_append(&stderr_buffer, cp, strlen(cp)); 652 xfree(cp); 653 } 654 } 655 max_fd = MAX(connection_in, connection_out); 656 max_fd = MAX(max_fd, fdin); 657 max_fd = MAX(max_fd, fdout); 658 max_fd = MAX(max_fd, fderr); 659 max_fd = MAX(max_fd, notify_pipe[0]); 660 661 /* Sleep in select() until we can do something. */ 662 wait_until_can_do_something(&readset, &writeset, &max_fd, 663 &nalloc, max_time_milliseconds); 664 665 if (received_sigterm) { 666 logit("Exiting on signal %d", received_sigterm); 667 /* Clean up sessions, utmp, etc. */ 668 cleanup_exit(255); 669 } 670 671 /* Process any channel events. */ 672 channel_after_select(readset, writeset); 673 674 /* Process input from the client and from program stdout/stderr. */ 675 process_input(readset); 676 677 /* Process output to the client and to program stdin. */ 678 process_output(writeset); 679 } 680 if (readset) 681 xfree(readset); 682 if (writeset) 683 xfree(writeset); 684 685 /* Cleanup and termination code. */ 686 687 /* Wait until all output has been sent to the client. */ 688 drain_output(); 689 690 debug("End of interactive session; stdin %ld, stdout (read %ld, sent %ld), stderr %ld bytes.", 691 stdin_bytes, fdout_bytes, stdout_bytes, stderr_bytes); 692 693 /* Free and clear the buffers. */ 694 buffer_free(&stdin_buffer); 695 buffer_free(&stdout_buffer); 696 buffer_free(&stderr_buffer); 697 698 /* Close the file descriptors. */ 699 if (fdout != -1) 700 close(fdout); 701 fdout = -1; 702 fdout_eof = 1; 703 if (fderr != -1) 704 close(fderr); 705 fderr = -1; 706 fderr_eof = 1; 707 if (fdin != -1) 708 close(fdin); 709 fdin = -1; 710 711 channel_free_all(); 712 713 /* We no longer want our SIGCHLD handler to be called. */ 714 signal(SIGCHLD, SIG_DFL); 715 716 while ((wait_pid = waitpid(-1, &wait_status, 0)) < 0) 717 if (errno != EINTR) 718 packet_disconnect("wait: %.100s", strerror(errno)); 719 if (wait_pid != pid) 720 error("Strange, wait returned pid %ld, expected %ld", 721 (long)wait_pid, (long)pid); 722 723 /* Check if it exited normally. */ 724 if (WIFEXITED(wait_status)) { 725 /* Yes, normal exit. Get exit status and send it to the client. */ 726 debug("Command exited with status %d.", WEXITSTATUS(wait_status)); 727 packet_start(SSH_SMSG_EXITSTATUS); 728 packet_put_int(WEXITSTATUS(wait_status)); 729 packet_send(); 730 packet_write_wait(); 731 732 /* 733 * Wait for exit confirmation. Note that there might be 734 * other packets coming before it; however, the program has 735 * already died so we just ignore them. The client is 736 * supposed to respond with the confirmation when it receives 737 * the exit status. 738 */ 739 do { 740 type = packet_read(); 741 } 742 while (type != SSH_CMSG_EXIT_CONFIRMATION); 743 744 debug("Received exit confirmation."); 745 return; 746 } 747 /* Check if the program terminated due to a signal. */ 748 if (WIFSIGNALED(wait_status)) 749 packet_disconnect("Command terminated on signal %d.", 750 WTERMSIG(wait_status)); 751 752 /* Some weird exit cause. Just exit. */ 753 packet_disconnect("wait returned status %04x.", wait_status); 754 /* NOTREACHED */ 755 } 756 757 static void 758 collect_children(void) 759 { 760 pid_t pid; 761 sigset_t oset, nset; 762 int status; 763 764 /* block SIGCHLD while we check for dead children */ 765 sigemptyset(&nset); 766 sigaddset(&nset, SIGCHLD); 767 sigprocmask(SIG_BLOCK, &nset, &oset); 768 if (child_terminated) { 769 debug("Received SIGCHLD."); 770 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 771 (pid < 0 && errno == EINTR)) 772 if (pid > 0) 773 session_close_by_pid(pid, status); 774 child_terminated = 0; 775 } 776 sigprocmask(SIG_SETMASK, &oset, NULL); 777 } 778 779 void 780 server_loop2(Authctxt *authctxt) 781 { 782 fd_set *readset = NULL, *writeset = NULL; 783 int rekeying = 0, max_fd, nalloc = 0; 784 785 debug("Entering interactive session for SSH2."); 786 787 signal(SIGCHLD, sigchld_handler); 788 child_terminated = 0; 789 connection_in = packet_get_connection_in(); 790 connection_out = packet_get_connection_out(); 791 792 if (!use_privsep) { 793 signal(SIGTERM, sigterm_handler); 794 signal(SIGINT, sigterm_handler); 795 signal(SIGQUIT, sigterm_handler); 796 } 797 798 notify_setup(); 799 800 max_fd = MAX(connection_in, connection_out); 801 max_fd = MAX(max_fd, notify_pipe[0]); 802 803 server_init_dispatch(); 804 805 for (;;) { 806 process_buffered_input_packets(); 807 808 rekeying = (xxx_kex != NULL && !xxx_kex->done); 809 810 if (!rekeying && packet_not_very_much_data_to_write()) 811 channel_output_poll(); 812 wait_until_can_do_something(&readset, &writeset, &max_fd, 813 &nalloc, 0); 814 815 if (received_sigterm) { 816 logit("Exiting on signal %d", received_sigterm); 817 /* Clean up sessions, utmp, etc. */ 818 cleanup_exit(255); 819 } 820 821 collect_children(); 822 if (!rekeying) { 823 channel_after_select(readset, writeset); 824 if (packet_need_rekeying()) { 825 debug("need rekeying"); 826 xxx_kex->done = 0; 827 kex_send_kexinit(xxx_kex); 828 } 829 } 830 process_input(readset); 831 if (connection_closed) 832 break; 833 process_output(writeset); 834 } 835 collect_children(); 836 837 if (readset) 838 xfree(readset); 839 if (writeset) 840 xfree(writeset); 841 842 /* free all channels, no more reads and writes */ 843 channel_free_all(); 844 845 /* free remaining sessions, e.g. remove wtmp entries */ 846 session_destroy_all(NULL); 847 } 848 849 static void 850 server_input_keep_alive(int type, u_int32_t seq, void *ctxt) 851 { 852 debug("Got %d/%u for keepalive", type, seq); 853 /* 854 * reset timeout, since we got a sane answer from the client. 855 * even if this was generated by something other than 856 * the bogus CHANNEL_REQUEST we send for keepalives. 857 */ 858 client_alive_timeouts = 0; 859 } 860 861 static void 862 server_input_stdin_data(int type, u_int32_t seq, void *ctxt) 863 { 864 char *data; 865 u_int data_len; 866 867 /* Stdin data from the client. Append it to the buffer. */ 868 /* Ignore any data if the client has closed stdin. */ 869 if (fdin == -1) 870 return; 871 data = packet_get_string(&data_len); 872 packet_check_eom(); 873 buffer_append(&stdin_buffer, data, data_len); 874 memset(data, 0, data_len); 875 xfree(data); 876 } 877 878 static void 879 server_input_eof(int type, u_int32_t seq, void *ctxt) 880 { 881 /* 882 * Eof from the client. The stdin descriptor to the 883 * program will be closed when all buffered data has 884 * drained. 885 */ 886 debug("EOF received for stdin."); 887 packet_check_eom(); 888 stdin_eof = 1; 889 } 890 891 static void 892 server_input_window_size(int type, u_int32_t seq, void *ctxt) 893 { 894 u_int row = packet_get_int(); 895 u_int col = packet_get_int(); 896 u_int xpixel = packet_get_int(); 897 u_int ypixel = packet_get_int(); 898 899 debug("Window change received."); 900 packet_check_eom(); 901 if (fdin != -1) 902 pty_change_window_size(fdin, row, col, xpixel, ypixel); 903 } 904 905 static Channel * 906 server_request_direct_tcpip(void) 907 { 908 Channel *c; 909 int sock; 910 char *target, *originator; 911 int target_port, originator_port; 912 913 target = packet_get_string(NULL); 914 target_port = packet_get_int(); 915 originator = packet_get_string(NULL); 916 originator_port = packet_get_int(); 917 packet_check_eom(); 918 919 debug("server_request_direct_tcpip: originator %s port %d, target %s port %d", 920 originator, originator_port, target, target_port); 921 922 /* XXX check permission */ 923 sock = channel_connect_to(target, target_port); 924 xfree(target); 925 xfree(originator); 926 if (sock < 0) 927 return NULL; 928 c = channel_new("direct-tcpip", SSH_CHANNEL_CONNECTING, 929 sock, sock, -1, CHAN_TCP_WINDOW_DEFAULT, 930 CHAN_TCP_PACKET_DEFAULT, 0, "direct-tcpip", 1); 931 return c; 932 } 933 934 static Channel * 935 server_request_tun(void) 936 { 937 Channel *c = NULL; 938 int mode, tun; 939 int sock; 940 941 mode = packet_get_int(); 942 switch (mode) { 943 case SSH_TUNMODE_POINTOPOINT: 944 case SSH_TUNMODE_ETHERNET: 945 break; 946 default: 947 packet_send_debug("Unsupported tunnel device mode."); 948 return NULL; 949 } 950 if ((options.permit_tun & mode) == 0) { 951 packet_send_debug("Server has rejected tunnel device " 952 "forwarding"); 953 return NULL; 954 } 955 956 tun = packet_get_int(); 957 if (forced_tun_device != -1) { 958 if (tun != SSH_TUNID_ANY && forced_tun_device != tun) 959 goto done; 960 tun = forced_tun_device; 961 } 962 sock = tun_open(tun, mode); 963 if (sock < 0) 964 goto done; 965 c = channel_new("tun", SSH_CHANNEL_OPEN, sock, sock, -1, 966 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1); 967 c->datagram = 1; 968 969 done: 970 if (c == NULL) 971 packet_send_debug("Failed to open the tunnel device."); 972 return c; 973 } 974 975 static Channel * 976 server_request_session(void) 977 { 978 Channel *c; 979 980 debug("input_session_request"); 981 packet_check_eom(); 982 /* 983 * A server session has no fd to read or write until a 984 * CHANNEL_REQUEST for a shell is made, so we set the type to 985 * SSH_CHANNEL_LARVAL. Additionally, a callback for handling all 986 * CHANNEL_REQUEST messages is registered. 987 */ 988 c = channel_new("session", SSH_CHANNEL_LARVAL, 989 -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT, 990 0, "server-session", 1); 991 if (session_open(the_authctxt, c->self) != 1) { 992 debug("session open failed, free channel %d", c->self); 993 channel_free(c); 994 return NULL; 995 } 996 channel_register_cleanup(c->self, session_close_by_channel, 0); 997 return c; 998 } 999 1000 static void 1001 server_input_channel_open(int type, u_int32_t seq, void *ctxt) 1002 { 1003 Channel *c = NULL; 1004 char *ctype; 1005 int rchan; 1006 u_int rmaxpack, rwindow, len; 1007 1008 ctype = packet_get_string(&len); 1009 rchan = packet_get_int(); 1010 rwindow = packet_get_int(); 1011 rmaxpack = packet_get_int(); 1012 1013 debug("server_input_channel_open: ctype %s rchan %d win %d max %d", 1014 ctype, rchan, rwindow, rmaxpack); 1015 1016 if (strcmp(ctype, "session") == 0) { 1017 c = server_request_session(); 1018 } else if (strcmp(ctype, "direct-tcpip") == 0) { 1019 c = server_request_direct_tcpip(); 1020 } else if (strcmp(ctype, "tun@openssh.com") == 0) { 1021 c = server_request_tun(); 1022 } 1023 if (c != NULL) { 1024 debug("server_input_channel_open: confirm %s", ctype); 1025 c->remote_id = rchan; 1026 c->remote_window = rwindow; 1027 c->remote_maxpacket = rmaxpack; 1028 if (c->type != SSH_CHANNEL_CONNECTING) { 1029 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION); 1030 packet_put_int(c->remote_id); 1031 packet_put_int(c->self); 1032 packet_put_int(c->local_window); 1033 packet_put_int(c->local_maxpacket); 1034 packet_send(); 1035 } 1036 } else { 1037 debug("server_input_channel_open: failure %s", ctype); 1038 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE); 1039 packet_put_int(rchan); 1040 packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED); 1041 if (!(datafellows & SSH_BUG_OPENFAILURE)) { 1042 packet_put_cstring("open failed"); 1043 packet_put_cstring(""); 1044 } 1045 packet_send(); 1046 } 1047 xfree(ctype); 1048 } 1049 1050 static void 1051 server_input_global_request(int type, u_int32_t seq, void *ctxt) 1052 { 1053 char *rtype; 1054 int want_reply; 1055 int success = 0; 1056 1057 rtype = packet_get_string(NULL); 1058 want_reply = packet_get_char(); 1059 debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply); 1060 1061 /* -R style forwarding */ 1062 if (strcmp(rtype, "tcpip-forward") == 0) { 1063 struct passwd *pw; 1064 char *listen_address; 1065 u_short listen_port; 1066 1067 pw = the_authctxt->pw; 1068 if (pw == NULL || !the_authctxt->valid) 1069 fatal("server_input_global_request: no/invalid user"); 1070 listen_address = packet_get_string(NULL); 1071 listen_port = (u_short)packet_get_int(); 1072 debug("server_input_global_request: tcpip-forward listen %s port %d", 1073 listen_address, listen_port); 1074 1075 /* check permissions */ 1076 if (!options.allow_tcp_forwarding || 1077 no_port_forwarding_flag || 1078 (listen_port < IPPORT_RESERVED && pw->pw_uid != 0)) { 1079 success = 0; 1080 packet_send_debug("Server has disabled port forwarding."); 1081 } else { 1082 /* Start listening on the port */ 1083 success = channel_setup_remote_fwd_listener( 1084 listen_address, listen_port, options.gateway_ports); 1085 } 1086 xfree(listen_address); 1087 } else if (strcmp(rtype, "cancel-tcpip-forward") == 0) { 1088 char *cancel_address; 1089 u_short cancel_port; 1090 1091 cancel_address = packet_get_string(NULL); 1092 cancel_port = (u_short)packet_get_int(); 1093 debug("%s: cancel-tcpip-forward addr %s port %d", __func__, 1094 cancel_address, cancel_port); 1095 1096 success = channel_cancel_rport_listener(cancel_address, 1097 cancel_port); 1098 xfree(cancel_address); 1099 } 1100 if (want_reply) { 1101 packet_start(success ? 1102 SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE); 1103 packet_send(); 1104 packet_write_wait(); 1105 } 1106 xfree(rtype); 1107 } 1108 1109 static void 1110 server_input_channel_req(int type, u_int32_t seq, void *ctxt) 1111 { 1112 Channel *c; 1113 int id, reply, success = 0; 1114 char *rtype; 1115 1116 id = packet_get_int(); 1117 rtype = packet_get_string(NULL); 1118 reply = packet_get_char(); 1119 1120 debug("server_input_channel_req: channel %d request %s reply %d", 1121 id, rtype, reply); 1122 1123 if ((c = channel_lookup(id)) == NULL) 1124 packet_disconnect("server_input_channel_req: " 1125 "unknown channel %d", id); 1126 if (c->type == SSH_CHANNEL_LARVAL || c->type == SSH_CHANNEL_OPEN) 1127 success = session_input_channel_req(c, rtype); 1128 if (reply) { 1129 packet_start(success ? 1130 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE); 1131 packet_put_int(c->remote_id); 1132 packet_send(); 1133 } 1134 xfree(rtype); 1135 } 1136 1137 static void 1138 server_init_dispatch_20(void) 1139 { 1140 debug("server_init_dispatch_20"); 1141 dispatch_init(&dispatch_protocol_error); 1142 dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); 1143 dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data); 1144 dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); 1145 dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); 1146 dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open); 1147 dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 1148 dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 1149 dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req); 1150 dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); 1151 dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request); 1152 /* client_alive */ 1153 dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_keep_alive); 1154 dispatch_set(SSH2_MSG_REQUEST_SUCCESS, &server_input_keep_alive); 1155 dispatch_set(SSH2_MSG_REQUEST_FAILURE, &server_input_keep_alive); 1156 /* rekeying */ 1157 dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); 1158 } 1159 static void 1160 server_init_dispatch_13(void) 1161 { 1162 debug("server_init_dispatch_13"); 1163 dispatch_init(NULL); 1164 dispatch_set(SSH_CMSG_EOF, &server_input_eof); 1165 dispatch_set(SSH_CMSG_STDIN_DATA, &server_input_stdin_data); 1166 dispatch_set(SSH_CMSG_WINDOW_SIZE, &server_input_window_size); 1167 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close); 1168 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation); 1169 dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data); 1170 dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 1171 dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 1172 dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open); 1173 } 1174 static void 1175 server_init_dispatch_15(void) 1176 { 1177 server_init_dispatch_13(); 1178 debug("server_init_dispatch_15"); 1179 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof); 1180 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_oclose); 1181 } 1182 static void 1183 server_init_dispatch(void) 1184 { 1185 if (compat20) 1186 server_init_dispatch_20(); 1187 else if (compat13) 1188 server_init_dispatch_13(); 1189 else 1190 server_init_dispatch_15(); 1191 } 1192