1 /* $OpenBSD: serverloop.c,v 1.145 2006/10/11 12:38:03 markus 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 logit("Timeout, client not responding."); 247 cleanup_exit(255); 248 } 249 250 /* 251 * send a bogus global/channel request with "wantreply", 252 * we should get back a failure 253 */ 254 if ((channel_id = channel_find_open()) == -1) { 255 packet_start(SSH2_MSG_GLOBAL_REQUEST); 256 packet_put_cstring("keepalive@openssh.com"); 257 packet_put_char(1); /* boolean: want reply */ 258 } else { 259 channel_request_start(channel_id, "keepalive@openssh.com", 1); 260 } 261 packet_send(); 262 } 263 264 /* 265 * Sleep in select() until we can do something. This will initialize the 266 * select masks. Upon return, the masks will indicate which descriptors 267 * have data or can accept data. Optionally, a maximum time can be specified 268 * for the duration of the wait (0 = infinite). 269 */ 270 static void 271 wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp, 272 u_int *nallocp, u_int max_time_milliseconds) 273 { 274 struct timeval tv, *tvp; 275 int ret; 276 int client_alive_scheduled = 0; 277 278 /* 279 * if using client_alive, set the max timeout accordingly, 280 * and indicate that this particular timeout was for client 281 * alive by setting the client_alive_scheduled flag. 282 * 283 * this could be randomized somewhat to make traffic 284 * analysis more difficult, but we're not doing it yet. 285 */ 286 if (compat20 && 287 max_time_milliseconds == 0 && options.client_alive_interval) { 288 client_alive_scheduled = 1; 289 max_time_milliseconds = options.client_alive_interval * 1000; 290 } 291 292 /* Allocate and update select() masks for channel descriptors. */ 293 channel_prepare_select(readsetp, writesetp, maxfdp, nallocp, 0); 294 295 if (compat20) { 296 #if 0 297 /* wrong: bad condition XXX */ 298 if (channel_not_very_much_buffered_data()) 299 #endif 300 FD_SET(connection_in, *readsetp); 301 } else { 302 /* 303 * Read packets from the client unless we have too much 304 * buffered stdin or channel data. 305 */ 306 if (buffer_len(&stdin_buffer) < buffer_high && 307 channel_not_very_much_buffered_data()) 308 FD_SET(connection_in, *readsetp); 309 /* 310 * If there is not too much data already buffered going to 311 * the client, try to get some more data from the program. 312 */ 313 if (packet_not_very_much_data_to_write()) { 314 if (!fdout_eof) 315 FD_SET(fdout, *readsetp); 316 if (!fderr_eof) 317 FD_SET(fderr, *readsetp); 318 } 319 /* 320 * If we have buffered data, try to write some of that data 321 * to the program. 322 */ 323 if (fdin != -1 && buffer_len(&stdin_buffer) > 0) 324 FD_SET(fdin, *writesetp); 325 } 326 notify_prepare(*readsetp); 327 328 /* 329 * If we have buffered packet data going to the client, mark that 330 * descriptor. 331 */ 332 if (packet_have_data_to_write()) 333 FD_SET(connection_out, *writesetp); 334 335 /* 336 * If child has terminated and there is enough buffer space to read 337 * from it, then read as much as is available and exit. 338 */ 339 if (child_terminated && packet_not_very_much_data_to_write()) 340 if (max_time_milliseconds == 0 || client_alive_scheduled) 341 max_time_milliseconds = 100; 342 343 if (max_time_milliseconds == 0) 344 tvp = NULL; 345 else { 346 tv.tv_sec = max_time_milliseconds / 1000; 347 tv.tv_usec = 1000 * (max_time_milliseconds % 1000); 348 tvp = &tv; 349 } 350 351 /* Wait for something to happen, or the timeout to expire. */ 352 ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp); 353 354 if (ret == -1) { 355 memset(*readsetp, 0, *nallocp); 356 memset(*writesetp, 0, *nallocp); 357 if (errno != EINTR) 358 error("select: %.100s", strerror(errno)); 359 } else if (ret == 0 && client_alive_scheduled) 360 client_alive_check(); 361 362 notify_done(*readsetp); 363 } 364 365 /* 366 * Processes input from the client and the program. Input data is stored 367 * in buffers and processed later. 368 */ 369 static void 370 process_input(fd_set *readset) 371 { 372 int len; 373 char buf[16384]; 374 375 /* Read and buffer any input data from the client. */ 376 if (FD_ISSET(connection_in, readset)) { 377 len = read(connection_in, buf, sizeof(buf)); 378 if (len == 0) { 379 verbose("Connection closed by %.100s", 380 get_remote_ipaddr()); 381 connection_closed = 1; 382 if (compat20) 383 return; 384 cleanup_exit(255); 385 } else if (len < 0) { 386 if (errno != EINTR && errno != EAGAIN) { 387 verbose("Read error from remote host " 388 "%.100s: %.100s", 389 get_remote_ipaddr(), strerror(errno)); 390 cleanup_exit(255); 391 } 392 } else { 393 /* Buffer any received data. */ 394 packet_process_incoming(buf, len); 395 } 396 } 397 if (compat20) 398 return; 399 400 /* Read and buffer any available stdout data from the program. */ 401 if (!fdout_eof && FD_ISSET(fdout, readset)) { 402 len = read(fdout, buf, sizeof(buf)); 403 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 404 /* do nothing */ 405 } else if (len <= 0) { 406 fdout_eof = 1; 407 } else { 408 buffer_append(&stdout_buffer, buf, len); 409 fdout_bytes += len; 410 } 411 } 412 /* Read and buffer any available stderr data from the program. */ 413 if (!fderr_eof && FD_ISSET(fderr, readset)) { 414 len = read(fderr, buf, sizeof(buf)); 415 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 416 /* do nothing */ 417 } else if (len <= 0) { 418 fderr_eof = 1; 419 } else { 420 buffer_append(&stderr_buffer, buf, len); 421 } 422 } 423 } 424 425 /* 426 * Sends data from internal buffers to client program stdin. 427 */ 428 static void 429 process_output(fd_set *writeset) 430 { 431 struct termios tio; 432 u_char *data; 433 u_int dlen; 434 int len; 435 436 /* Write buffered data to program stdin. */ 437 if (!compat20 && fdin != -1 && FD_ISSET(fdin, writeset)) { 438 data = buffer_ptr(&stdin_buffer); 439 dlen = buffer_len(&stdin_buffer); 440 len = write(fdin, data, dlen); 441 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 442 /* do nothing */ 443 } else if (len <= 0) { 444 if (fdin != fdout) 445 close(fdin); 446 else 447 shutdown(fdin, SHUT_WR); /* We will no longer send. */ 448 fdin = -1; 449 } else { 450 /* Successful write. */ 451 if (fdin_is_tty && dlen >= 1 && data[0] != '\r' && 452 tcgetattr(fdin, &tio) == 0 && 453 !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) { 454 /* 455 * Simulate echo to reduce the impact of 456 * traffic analysis 457 */ 458 packet_send_ignore(len); 459 packet_send(); 460 } 461 /* Consume the data from the buffer. */ 462 buffer_consume(&stdin_buffer, len); 463 /* Update the count of bytes written to the program. */ 464 stdin_bytes += len; 465 } 466 } 467 /* Send any buffered packet data to the client. */ 468 if (FD_ISSET(connection_out, writeset)) 469 packet_write_poll(); 470 } 471 472 /* 473 * Wait until all buffered output has been sent to the client. 474 * This is used when the program terminates. 475 */ 476 static void 477 drain_output(void) 478 { 479 /* Send any buffered stdout data to the client. */ 480 if (buffer_len(&stdout_buffer) > 0) { 481 packet_start(SSH_SMSG_STDOUT_DATA); 482 packet_put_string(buffer_ptr(&stdout_buffer), 483 buffer_len(&stdout_buffer)); 484 packet_send(); 485 /* Update the count of sent bytes. */ 486 stdout_bytes += buffer_len(&stdout_buffer); 487 } 488 /* Send any buffered stderr data to the client. */ 489 if (buffer_len(&stderr_buffer) > 0) { 490 packet_start(SSH_SMSG_STDERR_DATA); 491 packet_put_string(buffer_ptr(&stderr_buffer), 492 buffer_len(&stderr_buffer)); 493 packet_send(); 494 /* Update the count of sent bytes. */ 495 stderr_bytes += buffer_len(&stderr_buffer); 496 } 497 /* Wait until all buffered data has been written to the client. */ 498 packet_write_wait(); 499 } 500 501 static void 502 process_buffered_input_packets(void) 503 { 504 dispatch_run(DISPATCH_NONBLOCK, NULL, compat20 ? xxx_kex : NULL); 505 } 506 507 /* 508 * Performs the interactive session. This handles data transmission between 509 * the client and the program. Note that the notion of stdin, stdout, and 510 * stderr in this function is sort of reversed: this function writes to 511 * stdin (of the child program), and reads from stdout and stderr (of the 512 * child program). 513 */ 514 void 515 server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg) 516 { 517 fd_set *readset = NULL, *writeset = NULL; 518 int max_fd = 0; 519 u_int nalloc = 0; 520 int wait_status; /* Status returned by wait(). */ 521 pid_t wait_pid; /* pid returned by wait(). */ 522 int waiting_termination = 0; /* Have displayed waiting close message. */ 523 u_int max_time_milliseconds; 524 u_int previous_stdout_buffer_bytes; 525 u_int stdout_buffer_bytes; 526 int type; 527 528 debug("Entering interactive session."); 529 530 /* Initialize the SIGCHLD kludge. */ 531 child_terminated = 0; 532 signal(SIGCHLD, sigchld_handler); 533 534 if (!use_privsep) { 535 signal(SIGTERM, sigterm_handler); 536 signal(SIGINT, sigterm_handler); 537 signal(SIGQUIT, sigterm_handler); 538 } 539 540 /* Initialize our global variables. */ 541 fdin = fdin_arg; 542 fdout = fdout_arg; 543 fderr = fderr_arg; 544 545 /* nonblocking IO */ 546 set_nonblock(fdin); 547 set_nonblock(fdout); 548 /* we don't have stderr for interactive terminal sessions, see below */ 549 if (fderr != -1) 550 set_nonblock(fderr); 551 552 if (!(datafellows & SSH_BUG_IGNOREMSG) && isatty(fdin)) 553 fdin_is_tty = 1; 554 555 connection_in = packet_get_connection_in(); 556 connection_out = packet_get_connection_out(); 557 558 notify_setup(); 559 560 previous_stdout_buffer_bytes = 0; 561 562 /* Set approximate I/O buffer size. */ 563 if (packet_is_interactive()) 564 buffer_high = 4096; 565 else 566 buffer_high = 64 * 1024; 567 568 #if 0 569 /* Initialize max_fd to the maximum of the known file descriptors. */ 570 max_fd = MAX(connection_in, connection_out); 571 max_fd = MAX(max_fd, fdin); 572 max_fd = MAX(max_fd, fdout); 573 if (fderr != -1) 574 max_fd = MAX(max_fd, fderr); 575 #endif 576 577 /* Initialize Initialize buffers. */ 578 buffer_init(&stdin_buffer); 579 buffer_init(&stdout_buffer); 580 buffer_init(&stderr_buffer); 581 582 /* 583 * If we have no separate fderr (which is the case when we have a pty 584 * - there we cannot make difference between data sent to stdout and 585 * stderr), indicate that we have seen an EOF from stderr. This way 586 * we don't need to check the descriptor everywhere. 587 */ 588 if (fderr == -1) 589 fderr_eof = 1; 590 591 server_init_dispatch(); 592 593 /* Main loop of the server for the interactive session mode. */ 594 for (;;) { 595 596 /* Process buffered packets from the client. */ 597 process_buffered_input_packets(); 598 599 /* 600 * If we have received eof, and there is no more pending 601 * input data, cause a real eof by closing fdin. 602 */ 603 if (stdin_eof && fdin != -1 && buffer_len(&stdin_buffer) == 0) { 604 if (fdin != fdout) 605 close(fdin); 606 else 607 shutdown(fdin, SHUT_WR); /* We will no longer send. */ 608 fdin = -1; 609 } 610 /* Make packets from buffered stderr data to send to the client. */ 611 make_packets_from_stderr_data(); 612 613 /* 614 * Make packets from buffered stdout data to send to the 615 * client. If there is very little to send, this arranges to 616 * not send them now, but to wait a short while to see if we 617 * are getting more data. This is necessary, as some systems 618 * wake up readers from a pty after each separate character. 619 */ 620 max_time_milliseconds = 0; 621 stdout_buffer_bytes = buffer_len(&stdout_buffer); 622 if (stdout_buffer_bytes != 0 && stdout_buffer_bytes < 256 && 623 stdout_buffer_bytes != previous_stdout_buffer_bytes) { 624 /* try again after a while */ 625 max_time_milliseconds = 10; 626 } else { 627 /* Send it now. */ 628 make_packets_from_stdout_data(); 629 } 630 previous_stdout_buffer_bytes = buffer_len(&stdout_buffer); 631 632 /* Send channel data to the client. */ 633 if (packet_not_very_much_data_to_write()) 634 channel_output_poll(); 635 636 /* 637 * Bail out of the loop if the program has closed its output 638 * descriptors, and we have no more data to send to the 639 * client, and there is no pending buffered data. 640 */ 641 if (fdout_eof && fderr_eof && !packet_have_data_to_write() && 642 buffer_len(&stdout_buffer) == 0 && buffer_len(&stderr_buffer) == 0) { 643 if (!channel_still_open()) 644 break; 645 if (!waiting_termination) { 646 const char *s = "Waiting for forwarded connections to terminate...\r\n"; 647 char *cp; 648 waiting_termination = 1; 649 buffer_append(&stderr_buffer, s, strlen(s)); 650 651 /* Display list of open channels. */ 652 cp = channel_open_message(); 653 buffer_append(&stderr_buffer, cp, strlen(cp)); 654 xfree(cp); 655 } 656 } 657 max_fd = MAX(connection_in, connection_out); 658 max_fd = MAX(max_fd, fdin); 659 max_fd = MAX(max_fd, fdout); 660 max_fd = MAX(max_fd, fderr); 661 max_fd = MAX(max_fd, notify_pipe[0]); 662 663 /* Sleep in select() until we can do something. */ 664 wait_until_can_do_something(&readset, &writeset, &max_fd, 665 &nalloc, max_time_milliseconds); 666 667 if (received_sigterm) { 668 logit("Exiting on signal %d", received_sigterm); 669 /* Clean up sessions, utmp, etc. */ 670 cleanup_exit(255); 671 } 672 673 /* Process any channel events. */ 674 channel_after_select(readset, writeset); 675 676 /* Process input from the client and from program stdout/stderr. */ 677 process_input(readset); 678 679 /* Process output to the client and to program stdin. */ 680 process_output(writeset); 681 } 682 if (readset) 683 xfree(readset); 684 if (writeset) 685 xfree(writeset); 686 687 /* Cleanup and termination code. */ 688 689 /* Wait until all output has been sent to the client. */ 690 drain_output(); 691 692 debug("End of interactive session; stdin %ld, stdout (read %ld, sent %ld), stderr %ld bytes.", 693 stdin_bytes, fdout_bytes, stdout_bytes, stderr_bytes); 694 695 /* Free and clear the buffers. */ 696 buffer_free(&stdin_buffer); 697 buffer_free(&stdout_buffer); 698 buffer_free(&stderr_buffer); 699 700 /* Close the file descriptors. */ 701 if (fdout != -1) 702 close(fdout); 703 fdout = -1; 704 fdout_eof = 1; 705 if (fderr != -1) 706 close(fderr); 707 fderr = -1; 708 fderr_eof = 1; 709 if (fdin != -1) 710 close(fdin); 711 fdin = -1; 712 713 channel_free_all(); 714 715 /* We no longer want our SIGCHLD handler to be called. */ 716 signal(SIGCHLD, SIG_DFL); 717 718 while ((wait_pid = waitpid(-1, &wait_status, 0)) < 0) 719 if (errno != EINTR) 720 packet_disconnect("wait: %.100s", strerror(errno)); 721 if (wait_pid != pid) 722 error("Strange, wait returned pid %ld, expected %ld", 723 (long)wait_pid, (long)pid); 724 725 /* Check if it exited normally. */ 726 if (WIFEXITED(wait_status)) { 727 /* Yes, normal exit. Get exit status and send it to the client. */ 728 debug("Command exited with status %d.", WEXITSTATUS(wait_status)); 729 packet_start(SSH_SMSG_EXITSTATUS); 730 packet_put_int(WEXITSTATUS(wait_status)); 731 packet_send(); 732 packet_write_wait(); 733 734 /* 735 * Wait for exit confirmation. Note that there might be 736 * other packets coming before it; however, the program has 737 * already died so we just ignore them. The client is 738 * supposed to respond with the confirmation when it receives 739 * the exit status. 740 */ 741 do { 742 type = packet_read(); 743 } 744 while (type != SSH_CMSG_EXIT_CONFIRMATION); 745 746 debug("Received exit confirmation."); 747 return; 748 } 749 /* Check if the program terminated due to a signal. */ 750 if (WIFSIGNALED(wait_status)) 751 packet_disconnect("Command terminated on signal %d.", 752 WTERMSIG(wait_status)); 753 754 /* Some weird exit cause. Just exit. */ 755 packet_disconnect("wait returned status %04x.", wait_status); 756 /* NOTREACHED */ 757 } 758 759 static void 760 collect_children(void) 761 { 762 pid_t pid; 763 sigset_t oset, nset; 764 int status; 765 766 /* block SIGCHLD while we check for dead children */ 767 sigemptyset(&nset); 768 sigaddset(&nset, SIGCHLD); 769 sigprocmask(SIG_BLOCK, &nset, &oset); 770 if (child_terminated) { 771 debug("Received SIGCHLD."); 772 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 773 (pid < 0 && errno == EINTR)) 774 if (pid > 0) 775 session_close_by_pid(pid, status); 776 child_terminated = 0; 777 } 778 sigprocmask(SIG_SETMASK, &oset, NULL); 779 } 780 781 void 782 server_loop2(Authctxt *authctxt) 783 { 784 fd_set *readset = NULL, *writeset = NULL; 785 int rekeying = 0, max_fd, nalloc = 0; 786 787 debug("Entering interactive session for SSH2."); 788 789 signal(SIGCHLD, sigchld_handler); 790 child_terminated = 0; 791 connection_in = packet_get_connection_in(); 792 connection_out = packet_get_connection_out(); 793 794 if (!use_privsep) { 795 signal(SIGTERM, sigterm_handler); 796 signal(SIGINT, sigterm_handler); 797 signal(SIGQUIT, sigterm_handler); 798 } 799 800 notify_setup(); 801 802 max_fd = MAX(connection_in, connection_out); 803 max_fd = MAX(max_fd, notify_pipe[0]); 804 805 server_init_dispatch(); 806 807 for (;;) { 808 process_buffered_input_packets(); 809 810 rekeying = (xxx_kex != NULL && !xxx_kex->done); 811 812 if (!rekeying && packet_not_very_much_data_to_write()) 813 channel_output_poll(); 814 wait_until_can_do_something(&readset, &writeset, &max_fd, 815 &nalloc, 0); 816 817 if (received_sigterm) { 818 logit("Exiting on signal %d", received_sigterm); 819 /* Clean up sessions, utmp, etc. */ 820 cleanup_exit(255); 821 } 822 823 collect_children(); 824 if (!rekeying) { 825 channel_after_select(readset, writeset); 826 if (packet_need_rekeying()) { 827 debug("need rekeying"); 828 xxx_kex->done = 0; 829 kex_send_kexinit(xxx_kex); 830 } 831 } 832 process_input(readset); 833 if (connection_closed) 834 break; 835 process_output(writeset); 836 } 837 collect_children(); 838 839 if (readset) 840 xfree(readset); 841 if (writeset) 842 xfree(writeset); 843 844 /* free all channels, no more reads and writes */ 845 channel_free_all(); 846 847 /* free remaining sessions, e.g. remove wtmp entries */ 848 session_destroy_all(NULL); 849 } 850 851 static void 852 server_input_keep_alive(int type, u_int32_t seq, void *ctxt) 853 { 854 debug("Got %d/%u for keepalive", type, seq); 855 /* 856 * reset timeout, since we got a sane answer from the client. 857 * even if this was generated by something other than 858 * the bogus CHANNEL_REQUEST we send for keepalives. 859 */ 860 client_alive_timeouts = 0; 861 } 862 863 static void 864 server_input_stdin_data(int type, u_int32_t seq, void *ctxt) 865 { 866 char *data; 867 u_int data_len; 868 869 /* Stdin data from the client. Append it to the buffer. */ 870 /* Ignore any data if the client has closed stdin. */ 871 if (fdin == -1) 872 return; 873 data = packet_get_string(&data_len); 874 packet_check_eom(); 875 buffer_append(&stdin_buffer, data, data_len); 876 memset(data, 0, data_len); 877 xfree(data); 878 } 879 880 static void 881 server_input_eof(int type, u_int32_t seq, void *ctxt) 882 { 883 /* 884 * Eof from the client. The stdin descriptor to the 885 * program will be closed when all buffered data has 886 * drained. 887 */ 888 debug("EOF received for stdin."); 889 packet_check_eom(); 890 stdin_eof = 1; 891 } 892 893 static void 894 server_input_window_size(int type, u_int32_t seq, void *ctxt) 895 { 896 u_int row = packet_get_int(); 897 u_int col = packet_get_int(); 898 u_int xpixel = packet_get_int(); 899 u_int ypixel = packet_get_int(); 900 901 debug("Window change received."); 902 packet_check_eom(); 903 if (fdin != -1) 904 pty_change_window_size(fdin, row, col, xpixel, ypixel); 905 } 906 907 static Channel * 908 server_request_direct_tcpip(void) 909 { 910 Channel *c; 911 int sock; 912 char *target, *originator; 913 int target_port, originator_port; 914 915 target = packet_get_string(NULL); 916 target_port = packet_get_int(); 917 originator = packet_get_string(NULL); 918 originator_port = packet_get_int(); 919 packet_check_eom(); 920 921 debug("server_request_direct_tcpip: originator %s port %d, target %s port %d", 922 originator, originator_port, target, target_port); 923 924 /* XXX check permission */ 925 sock = channel_connect_to(target, target_port); 926 xfree(target); 927 xfree(originator); 928 if (sock < 0) 929 return NULL; 930 c = channel_new("direct-tcpip", SSH_CHANNEL_CONNECTING, 931 sock, sock, -1, CHAN_TCP_WINDOW_DEFAULT, 932 CHAN_TCP_PACKET_DEFAULT, 0, "direct-tcpip", 1); 933 return c; 934 } 935 936 static Channel * 937 server_request_tun(void) 938 { 939 Channel *c = NULL; 940 int mode, tun; 941 int sock; 942 943 mode = packet_get_int(); 944 switch (mode) { 945 case SSH_TUNMODE_POINTOPOINT: 946 case SSH_TUNMODE_ETHERNET: 947 break; 948 default: 949 packet_send_debug("Unsupported tunnel device mode."); 950 return NULL; 951 } 952 if ((options.permit_tun & mode) == 0) { 953 packet_send_debug("Server has rejected tunnel device " 954 "forwarding"); 955 return NULL; 956 } 957 958 tun = packet_get_int(); 959 if (forced_tun_device != -1) { 960 if (tun != SSH_TUNID_ANY && forced_tun_device != tun) 961 goto done; 962 tun = forced_tun_device; 963 } 964 sock = tun_open(tun, mode); 965 if (sock < 0) 966 goto done; 967 c = channel_new("tun", SSH_CHANNEL_OPEN, sock, sock, -1, 968 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1); 969 c->datagram = 1; 970 971 done: 972 if (c == NULL) 973 packet_send_debug("Failed to open the tunnel device."); 974 return c; 975 } 976 977 static Channel * 978 server_request_session(void) 979 { 980 Channel *c; 981 982 debug("input_session_request"); 983 packet_check_eom(); 984 /* 985 * A server session has no fd to read or write until a 986 * CHANNEL_REQUEST for a shell is made, so we set the type to 987 * SSH_CHANNEL_LARVAL. Additionally, a callback for handling all 988 * CHANNEL_REQUEST messages is registered. 989 */ 990 c = channel_new("session", SSH_CHANNEL_LARVAL, 991 -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT, 992 0, "server-session", 1); 993 if (session_open(the_authctxt, c->self) != 1) { 994 debug("session open failed, free channel %d", c->self); 995 channel_free(c); 996 return NULL; 997 } 998 channel_register_cleanup(c->self, session_close_by_channel, 0); 999 return c; 1000 } 1001 1002 static void 1003 server_input_channel_open(int type, u_int32_t seq, void *ctxt) 1004 { 1005 Channel *c = NULL; 1006 char *ctype; 1007 int rchan; 1008 u_int rmaxpack, rwindow, len; 1009 1010 ctype = packet_get_string(&len); 1011 rchan = packet_get_int(); 1012 rwindow = packet_get_int(); 1013 rmaxpack = packet_get_int(); 1014 1015 debug("server_input_channel_open: ctype %s rchan %d win %d max %d", 1016 ctype, rchan, rwindow, rmaxpack); 1017 1018 if (strcmp(ctype, "session") == 0) { 1019 c = server_request_session(); 1020 } else if (strcmp(ctype, "direct-tcpip") == 0) { 1021 c = server_request_direct_tcpip(); 1022 } else if (strcmp(ctype, "tun@openssh.com") == 0) { 1023 c = server_request_tun(); 1024 } 1025 if (c != NULL) { 1026 debug("server_input_channel_open: confirm %s", ctype); 1027 c->remote_id = rchan; 1028 c->remote_window = rwindow; 1029 c->remote_maxpacket = rmaxpack; 1030 if (c->type != SSH_CHANNEL_CONNECTING) { 1031 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION); 1032 packet_put_int(c->remote_id); 1033 packet_put_int(c->self); 1034 packet_put_int(c->local_window); 1035 packet_put_int(c->local_maxpacket); 1036 packet_send(); 1037 } 1038 } else { 1039 debug("server_input_channel_open: failure %s", ctype); 1040 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE); 1041 packet_put_int(rchan); 1042 packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED); 1043 if (!(datafellows & SSH_BUG_OPENFAILURE)) { 1044 packet_put_cstring("open failed"); 1045 packet_put_cstring(""); 1046 } 1047 packet_send(); 1048 } 1049 xfree(ctype); 1050 } 1051 1052 static void 1053 server_input_global_request(int type, u_int32_t seq, void *ctxt) 1054 { 1055 char *rtype; 1056 int want_reply; 1057 int success = 0; 1058 1059 rtype = packet_get_string(NULL); 1060 want_reply = packet_get_char(); 1061 debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply); 1062 1063 /* -R style forwarding */ 1064 if (strcmp(rtype, "tcpip-forward") == 0) { 1065 struct passwd *pw; 1066 char *listen_address; 1067 u_short listen_port; 1068 1069 pw = the_authctxt->pw; 1070 if (pw == NULL || !the_authctxt->valid) 1071 fatal("server_input_global_request: no/invalid user"); 1072 listen_address = packet_get_string(NULL); 1073 listen_port = (u_short)packet_get_int(); 1074 debug("server_input_global_request: tcpip-forward listen %s port %d", 1075 listen_address, listen_port); 1076 1077 /* check permissions */ 1078 if (!options.allow_tcp_forwarding || 1079 no_port_forwarding_flag || 1080 (listen_port < IPPORT_RESERVED && pw->pw_uid != 0)) { 1081 success = 0; 1082 packet_send_debug("Server has disabled port forwarding."); 1083 } else { 1084 /* Start listening on the port */ 1085 success = channel_setup_remote_fwd_listener( 1086 listen_address, listen_port, options.gateway_ports); 1087 } 1088 xfree(listen_address); 1089 } else if (strcmp(rtype, "cancel-tcpip-forward") == 0) { 1090 char *cancel_address; 1091 u_short cancel_port; 1092 1093 cancel_address = packet_get_string(NULL); 1094 cancel_port = (u_short)packet_get_int(); 1095 debug("%s: cancel-tcpip-forward addr %s port %d", __func__, 1096 cancel_address, cancel_port); 1097 1098 success = channel_cancel_rport_listener(cancel_address, 1099 cancel_port); 1100 xfree(cancel_address); 1101 } 1102 if (want_reply) { 1103 packet_start(success ? 1104 SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE); 1105 packet_send(); 1106 packet_write_wait(); 1107 } 1108 xfree(rtype); 1109 } 1110 1111 static void 1112 server_input_channel_req(int type, u_int32_t seq, void *ctxt) 1113 { 1114 Channel *c; 1115 int id, reply, success = 0; 1116 char *rtype; 1117 1118 id = packet_get_int(); 1119 rtype = packet_get_string(NULL); 1120 reply = packet_get_char(); 1121 1122 debug("server_input_channel_req: channel %d request %s reply %d", 1123 id, rtype, reply); 1124 1125 if ((c = channel_lookup(id)) == NULL) 1126 packet_disconnect("server_input_channel_req: " 1127 "unknown channel %d", id); 1128 if (c->type == SSH_CHANNEL_LARVAL || c->type == SSH_CHANNEL_OPEN) 1129 success = session_input_channel_req(c, rtype); 1130 if (reply) { 1131 packet_start(success ? 1132 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE); 1133 packet_put_int(c->remote_id); 1134 packet_send(); 1135 } 1136 xfree(rtype); 1137 } 1138 1139 static void 1140 server_init_dispatch_20(void) 1141 { 1142 debug("server_init_dispatch_20"); 1143 dispatch_init(&dispatch_protocol_error); 1144 dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); 1145 dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data); 1146 dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); 1147 dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); 1148 dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open); 1149 dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 1150 dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 1151 dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req); 1152 dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); 1153 dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request); 1154 /* client_alive */ 1155 dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_keep_alive); 1156 dispatch_set(SSH2_MSG_REQUEST_SUCCESS, &server_input_keep_alive); 1157 dispatch_set(SSH2_MSG_REQUEST_FAILURE, &server_input_keep_alive); 1158 /* rekeying */ 1159 dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); 1160 } 1161 static void 1162 server_init_dispatch_13(void) 1163 { 1164 debug("server_init_dispatch_13"); 1165 dispatch_init(NULL); 1166 dispatch_set(SSH_CMSG_EOF, &server_input_eof); 1167 dispatch_set(SSH_CMSG_STDIN_DATA, &server_input_stdin_data); 1168 dispatch_set(SSH_CMSG_WINDOW_SIZE, &server_input_window_size); 1169 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close); 1170 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation); 1171 dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data); 1172 dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 1173 dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 1174 dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open); 1175 } 1176 static void 1177 server_init_dispatch_15(void) 1178 { 1179 server_init_dispatch_13(); 1180 debug("server_init_dispatch_15"); 1181 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof); 1182 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_oclose); 1183 } 1184 static void 1185 server_init_dispatch(void) 1186 { 1187 if (compat20) 1188 server_init_dispatch_20(); 1189 else if (compat13) 1190 server_init_dispatch_13(); 1191 else 1192 server_init_dispatch_15(); 1193 } 1194