1 /* $OpenBSD: serverloop.c,v 1.148 2008/02/22 20:44:02 dtucker 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. */ 103 104 /* 105 * This SIGCHLD kludge is used to detect when the child exits. The server 106 * will exit after that, as soon as forwarded connections have terminated. 107 */ 108 109 static volatile sig_atomic_t child_terminated = 0; /* The child has terminated. */ 110 111 /* Cleanup on signals (!use_privsep case only) */ 112 static volatile sig_atomic_t received_sigterm = 0; 113 114 /* prototypes */ 115 static void server_init_dispatch(void); 116 117 /* 118 * we write to this pipe if a SIGCHLD is caught in order to avoid 119 * the race between select() and child_terminated 120 */ 121 static int notify_pipe[2]; 122 static void 123 notify_setup(void) 124 { 125 if (pipe(notify_pipe) < 0) { 126 error("pipe(notify_pipe) failed %s", strerror(errno)); 127 } else if ((fcntl(notify_pipe[0], F_SETFD, 1) == -1) || 128 (fcntl(notify_pipe[1], F_SETFD, 1) == -1)) { 129 error("fcntl(notify_pipe, F_SETFD) failed %s", strerror(errno)); 130 close(notify_pipe[0]); 131 close(notify_pipe[1]); 132 } else { 133 set_nonblock(notify_pipe[0]); 134 set_nonblock(notify_pipe[1]); 135 return; 136 } 137 notify_pipe[0] = -1; /* read end */ 138 notify_pipe[1] = -1; /* write end */ 139 } 140 static void 141 notify_parent(void) 142 { 143 if (notify_pipe[1] != -1) 144 write(notify_pipe[1], "", 1); 145 } 146 static void 147 notify_prepare(fd_set *readset) 148 { 149 if (notify_pipe[0] != -1) 150 FD_SET(notify_pipe[0], readset); 151 } 152 static void 153 notify_done(fd_set *readset) 154 { 155 char c; 156 157 if (notify_pipe[0] != -1 && FD_ISSET(notify_pipe[0], readset)) 158 while (read(notify_pipe[0], &c, 1) != -1) 159 debug2("notify_done: reading"); 160 } 161 162 /*ARGSUSED*/ 163 static void 164 sigchld_handler(int sig) 165 { 166 int save_errno = errno; 167 child_terminated = 1; 168 signal(SIGCHLD, sigchld_handler); 169 notify_parent(); 170 errno = save_errno; 171 } 172 173 /*ARGSUSED*/ 174 static void 175 sigterm_handler(int sig) 176 { 177 received_sigterm = sig; 178 } 179 180 /* 181 * Make packets from buffered stderr data, and buffer it for sending 182 * to the client. 183 */ 184 static void 185 make_packets_from_stderr_data(void) 186 { 187 u_int len; 188 189 /* Send buffered stderr data to the client. */ 190 while (buffer_len(&stderr_buffer) > 0 && 191 packet_not_very_much_data_to_write()) { 192 len = buffer_len(&stderr_buffer); 193 if (packet_is_interactive()) { 194 if (len > 512) 195 len = 512; 196 } else { 197 /* Keep the packets at reasonable size. */ 198 if (len > packet_get_maxsize()) 199 len = packet_get_maxsize(); 200 } 201 packet_start(SSH_SMSG_STDERR_DATA); 202 packet_put_string(buffer_ptr(&stderr_buffer), len); 203 packet_send(); 204 buffer_consume(&stderr_buffer, len); 205 stderr_bytes += len; 206 } 207 } 208 209 /* 210 * Make packets from buffered stdout data, and buffer it for sending to the 211 * client. 212 */ 213 static void 214 make_packets_from_stdout_data(void) 215 { 216 u_int len; 217 218 /* Send buffered stdout data to the client. */ 219 while (buffer_len(&stdout_buffer) > 0 && 220 packet_not_very_much_data_to_write()) { 221 len = buffer_len(&stdout_buffer); 222 if (packet_is_interactive()) { 223 if (len > 512) 224 len = 512; 225 } else { 226 /* Keep the packets at reasonable size. */ 227 if (len > packet_get_maxsize()) 228 len = packet_get_maxsize(); 229 } 230 packet_start(SSH_SMSG_STDOUT_DATA); 231 packet_put_string(buffer_ptr(&stdout_buffer), len); 232 packet_send(); 233 buffer_consume(&stdout_buffer, len); 234 stdout_bytes += len; 235 } 236 } 237 238 static void 239 client_alive_check(void) 240 { 241 int channel_id; 242 243 /* timeout, check to see how many we have had */ 244 if (++keep_alive_timeouts > options.client_alive_count_max) { 245 logit("Timeout, client not responding."); 246 cleanup_exit(255); 247 } 248 249 /* 250 * send a bogus global/channel request with "wantreply", 251 * we should get back a failure 252 */ 253 if ((channel_id = channel_find_open()) == -1) { 254 packet_start(SSH2_MSG_GLOBAL_REQUEST); 255 packet_put_cstring("keepalive@openssh.com"); 256 packet_put_char(1); /* boolean: want reply */ 257 } else { 258 channel_request_start(channel_id, "keepalive@openssh.com", 1); 259 } 260 packet_send(); 261 } 262 263 /* 264 * Sleep in select() until we can do something. This will initialize the 265 * select masks. Upon return, the masks will indicate which descriptors 266 * have data or can accept data. Optionally, a maximum time can be specified 267 * for the duration of the wait (0 = infinite). 268 */ 269 static void 270 wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp, 271 u_int *nallocp, u_int max_time_milliseconds) 272 { 273 struct timeval tv, *tvp; 274 int ret; 275 int client_alive_scheduled = 0; 276 277 /* 278 * if using client_alive, set the max timeout accordingly, 279 * and indicate that this particular timeout was for client 280 * alive by setting the client_alive_scheduled flag. 281 * 282 * this could be randomized somewhat to make traffic 283 * analysis more difficult, but we're not doing it yet. 284 */ 285 if (compat20 && 286 max_time_milliseconds == 0 && options.client_alive_interval) { 287 client_alive_scheduled = 1; 288 max_time_milliseconds = options.client_alive_interval * 1000; 289 } 290 291 /* Allocate and update select() masks for channel descriptors. */ 292 channel_prepare_select(readsetp, writesetp, maxfdp, nallocp, 0); 293 294 if (compat20) { 295 #if 0 296 /* wrong: bad condition XXX */ 297 if (channel_not_very_much_buffered_data()) 298 #endif 299 FD_SET(connection_in, *readsetp); 300 } else { 301 /* 302 * Read packets from the client unless we have too much 303 * buffered stdin or channel data. 304 */ 305 if (buffer_len(&stdin_buffer) < buffer_high && 306 channel_not_very_much_buffered_data()) 307 FD_SET(connection_in, *readsetp); 308 /* 309 * If there is not too much data already buffered going to 310 * the client, try to get some more data from the program. 311 */ 312 if (packet_not_very_much_data_to_write()) { 313 if (!fdout_eof) 314 FD_SET(fdout, *readsetp); 315 if (!fderr_eof) 316 FD_SET(fderr, *readsetp); 317 } 318 /* 319 * If we have buffered data, try to write some of that data 320 * to the program. 321 */ 322 if (fdin != -1 && buffer_len(&stdin_buffer) > 0) 323 FD_SET(fdin, *writesetp); 324 } 325 notify_prepare(*readsetp); 326 327 /* 328 * If we have buffered packet data going to the client, mark that 329 * descriptor. 330 */ 331 if (packet_have_data_to_write()) 332 FD_SET(connection_out, *writesetp); 333 334 /* 335 * If child has terminated and there is enough buffer space to read 336 * from it, then read as much as is available and exit. 337 */ 338 if (child_terminated && packet_not_very_much_data_to_write()) 339 if (max_time_milliseconds == 0 || client_alive_scheduled) 340 max_time_milliseconds = 100; 341 342 if (max_time_milliseconds == 0) 343 tvp = NULL; 344 else { 345 tv.tv_sec = max_time_milliseconds / 1000; 346 tv.tv_usec = 1000 * (max_time_milliseconds % 1000); 347 tvp = &tv; 348 } 349 350 /* Wait for something to happen, or the timeout to expire. */ 351 ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp); 352 353 if (ret == -1) { 354 memset(*readsetp, 0, *nallocp); 355 memset(*writesetp, 0, *nallocp); 356 if (errno != EINTR) 357 error("select: %.100s", strerror(errno)); 358 } else if (ret == 0 && client_alive_scheduled) 359 client_alive_check(); 360 361 notify_done(*readsetp); 362 } 363 364 /* 365 * Processes input from the client and the program. Input data is stored 366 * in buffers and processed later. 367 */ 368 static void 369 process_input(fd_set *readset) 370 { 371 int len; 372 char buf[16384]; 373 374 /* Read and buffer any input data from the client. */ 375 if (FD_ISSET(connection_in, readset)) { 376 len = read(connection_in, buf, sizeof(buf)); 377 if (len == 0) { 378 verbose("Connection closed by %.100s", 379 get_remote_ipaddr()); 380 connection_closed = 1; 381 if (compat20) 382 return; 383 cleanup_exit(255); 384 } else if (len < 0) { 385 if (errno != EINTR && errno != EAGAIN) { 386 verbose("Read error from remote host " 387 "%.100s: %.100s", 388 get_remote_ipaddr(), strerror(errno)); 389 cleanup_exit(255); 390 } 391 } else { 392 /* Buffer any received data. */ 393 packet_process_incoming(buf, len); 394 } 395 } 396 if (compat20) 397 return; 398 399 /* Read and buffer any available stdout data from the program. */ 400 if (!fdout_eof && FD_ISSET(fdout, readset)) { 401 len = read(fdout, buf, sizeof(buf)); 402 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 403 /* do nothing */ 404 } else if (len <= 0) { 405 fdout_eof = 1; 406 } else { 407 buffer_append(&stdout_buffer, buf, len); 408 fdout_bytes += len; 409 } 410 } 411 /* Read and buffer any available stderr data from the program. */ 412 if (!fderr_eof && FD_ISSET(fderr, readset)) { 413 len = read(fderr, buf, sizeof(buf)); 414 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 415 /* do nothing */ 416 } else if (len <= 0) { 417 fderr_eof = 1; 418 } else { 419 buffer_append(&stderr_buffer, buf, len); 420 } 421 } 422 } 423 424 /* 425 * Sends data from internal buffers to client program stdin. 426 */ 427 static void 428 process_output(fd_set *writeset) 429 { 430 struct termios tio; 431 u_char *data; 432 u_int dlen; 433 int len; 434 435 /* Write buffered data to program stdin. */ 436 if (!compat20 && fdin != -1 && FD_ISSET(fdin, writeset)) { 437 data = buffer_ptr(&stdin_buffer); 438 dlen = buffer_len(&stdin_buffer); 439 len = write(fdin, data, dlen); 440 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 441 /* do nothing */ 442 } else if (len <= 0) { 443 if (fdin != fdout) 444 close(fdin); 445 else 446 shutdown(fdin, SHUT_WR); /* We will no longer send. */ 447 fdin = -1; 448 } else { 449 /* Successful write. */ 450 if (fdin_is_tty && dlen >= 1 && data[0] != '\r' && 451 tcgetattr(fdin, &tio) == 0 && 452 !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) { 453 /* 454 * Simulate echo to reduce the impact of 455 * traffic analysis 456 */ 457 packet_send_ignore(len); 458 packet_send(); 459 } 460 /* Consume the data from the buffer. */ 461 buffer_consume(&stdin_buffer, len); 462 /* Update the count of bytes written to the program. */ 463 stdin_bytes += len; 464 } 465 } 466 /* Send any buffered packet data to the client. */ 467 if (FD_ISSET(connection_out, writeset)) 468 packet_write_poll(); 469 } 470 471 /* 472 * Wait until all buffered output has been sent to the client. 473 * This is used when the program terminates. 474 */ 475 static void 476 drain_output(void) 477 { 478 /* Send any buffered stdout data to the client. */ 479 if (buffer_len(&stdout_buffer) > 0) { 480 packet_start(SSH_SMSG_STDOUT_DATA); 481 packet_put_string(buffer_ptr(&stdout_buffer), 482 buffer_len(&stdout_buffer)); 483 packet_send(); 484 /* Update the count of sent bytes. */ 485 stdout_bytes += buffer_len(&stdout_buffer); 486 } 487 /* Send any buffered stderr data to the client. */ 488 if (buffer_len(&stderr_buffer) > 0) { 489 packet_start(SSH_SMSG_STDERR_DATA); 490 packet_put_string(buffer_ptr(&stderr_buffer), 491 buffer_len(&stderr_buffer)); 492 packet_send(); 493 /* Update the count of sent bytes. */ 494 stderr_bytes += buffer_len(&stderr_buffer); 495 } 496 /* Wait until all buffered data has been written to the client. */ 497 packet_write_wait(); 498 } 499 500 static void 501 process_buffered_input_packets(void) 502 { 503 dispatch_run(DISPATCH_NONBLOCK, NULL, compat20 ? xxx_kex : NULL); 504 } 505 506 /* 507 * Performs the interactive session. This handles data transmission between 508 * the client and the program. Note that the notion of stdin, stdout, and 509 * stderr in this function is sort of reversed: this function writes to 510 * stdin (of the child program), and reads from stdout and stderr (of the 511 * child program). 512 */ 513 void 514 server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg) 515 { 516 fd_set *readset = NULL, *writeset = NULL; 517 int max_fd = 0; 518 u_int nalloc = 0; 519 int wait_status; /* Status returned by wait(). */ 520 pid_t wait_pid; /* pid returned by wait(). */ 521 int waiting_termination = 0; /* Have displayed waiting close message. */ 522 u_int max_time_milliseconds; 523 u_int previous_stdout_buffer_bytes; 524 u_int stdout_buffer_bytes; 525 int type; 526 527 debug("Entering interactive session."); 528 529 /* Initialize the SIGCHLD kludge. */ 530 child_terminated = 0; 531 signal(SIGCHLD, sigchld_handler); 532 533 if (!use_privsep) { 534 signal(SIGTERM, sigterm_handler); 535 signal(SIGINT, sigterm_handler); 536 signal(SIGQUIT, sigterm_handler); 537 } 538 539 /* Initialize our global variables. */ 540 fdin = fdin_arg; 541 fdout = fdout_arg; 542 fderr = fderr_arg; 543 544 /* nonblocking IO */ 545 set_nonblock(fdin); 546 set_nonblock(fdout); 547 /* we don't have stderr for interactive terminal sessions, see below */ 548 if (fderr != -1) 549 set_nonblock(fderr); 550 551 if (!(datafellows & SSH_BUG_IGNOREMSG) && isatty(fdin)) 552 fdin_is_tty = 1; 553 554 connection_in = packet_get_connection_in(); 555 connection_out = packet_get_connection_out(); 556 557 notify_setup(); 558 559 previous_stdout_buffer_bytes = 0; 560 561 /* Set approximate I/O buffer size. */ 562 if (packet_is_interactive()) 563 buffer_high = 4096; 564 else 565 buffer_high = 64 * 1024; 566 567 #if 0 568 /* Initialize max_fd to the maximum of the known file descriptors. */ 569 max_fd = MAX(connection_in, connection_out); 570 max_fd = MAX(max_fd, fdin); 571 max_fd = MAX(max_fd, fdout); 572 if (fderr != -1) 573 max_fd = MAX(max_fd, fderr); 574 #endif 575 576 /* Initialize Initialize buffers. */ 577 buffer_init(&stdin_buffer); 578 buffer_init(&stdout_buffer); 579 buffer_init(&stderr_buffer); 580 581 /* 582 * If we have no separate fderr (which is the case when we have a pty 583 * - there we cannot make difference between data sent to stdout and 584 * stderr), indicate that we have seen an EOF from stderr. This way 585 * we don't need to check the descriptor everywhere. 586 */ 587 if (fderr == -1) 588 fderr_eof = 1; 589 590 server_init_dispatch(); 591 592 /* Main loop of the server for the interactive session mode. */ 593 for (;;) { 594 595 /* Process buffered packets from the client. */ 596 process_buffered_input_packets(); 597 598 /* 599 * If we have received eof, and there is no more pending 600 * input data, cause a real eof by closing fdin. 601 */ 602 if (stdin_eof && fdin != -1 && buffer_len(&stdin_buffer) == 0) { 603 if (fdin != fdout) 604 close(fdin); 605 else 606 shutdown(fdin, SHUT_WR); /* We will no longer send. */ 607 fdin = -1; 608 } 609 /* Make packets from buffered stderr data to send to the client. */ 610 make_packets_from_stderr_data(); 611 612 /* 613 * Make packets from buffered stdout data to send to the 614 * client. If there is very little to send, this arranges to 615 * not send them now, but to wait a short while to see if we 616 * are getting more data. This is necessary, as some systems 617 * wake up readers from a pty after each separate character. 618 */ 619 max_time_milliseconds = 0; 620 stdout_buffer_bytes = buffer_len(&stdout_buffer); 621 if (stdout_buffer_bytes != 0 && stdout_buffer_bytes < 256 && 622 stdout_buffer_bytes != previous_stdout_buffer_bytes) { 623 /* try again after a while */ 624 max_time_milliseconds = 10; 625 } else { 626 /* Send it now. */ 627 make_packets_from_stdout_data(); 628 } 629 previous_stdout_buffer_bytes = buffer_len(&stdout_buffer); 630 631 /* Send channel data to the client. */ 632 if (packet_not_very_much_data_to_write()) 633 channel_output_poll(); 634 635 /* 636 * Bail out of the loop if the program has closed its output 637 * descriptors, and we have no more data to send to the 638 * client, and there is no pending buffered data. 639 */ 640 if (fdout_eof && fderr_eof && !packet_have_data_to_write() && 641 buffer_len(&stdout_buffer) == 0 && buffer_len(&stderr_buffer) == 0) { 642 if (!channel_still_open()) 643 break; 644 if (!waiting_termination) { 645 const char *s = "Waiting for forwarded connections to terminate...\r\n"; 646 char *cp; 647 waiting_termination = 1; 648 buffer_append(&stderr_buffer, s, strlen(s)); 649 650 /* Display list of open channels. */ 651 cp = channel_open_message(); 652 buffer_append(&stderr_buffer, cp, strlen(cp)); 653 xfree(cp); 654 } 655 } 656 max_fd = MAX(connection_in, connection_out); 657 max_fd = MAX(max_fd, fdin); 658 max_fd = MAX(max_fd, fdout); 659 max_fd = MAX(max_fd, fderr); 660 max_fd = MAX(max_fd, notify_pipe[0]); 661 662 /* Sleep in select() until we can do something. */ 663 wait_until_can_do_something(&readset, &writeset, &max_fd, 664 &nalloc, max_time_milliseconds); 665 666 if (received_sigterm) { 667 logit("Exiting on signal %d", received_sigterm); 668 /* Clean up sessions, utmp, etc. */ 669 cleanup_exit(255); 670 } 671 672 /* Process any channel events. */ 673 channel_after_select(readset, writeset); 674 675 /* Process input from the client and from program stdout/stderr. */ 676 process_input(readset); 677 678 /* Process output to the client and to program stdin. */ 679 process_output(writeset); 680 } 681 if (readset) 682 xfree(readset); 683 if (writeset) 684 xfree(writeset); 685 686 /* Cleanup and termination code. */ 687 688 /* Wait until all output has been sent to the client. */ 689 drain_output(); 690 691 debug("End of interactive session; stdin %ld, stdout (read %ld, sent %ld), stderr %ld bytes.", 692 stdin_bytes, fdout_bytes, stdout_bytes, stderr_bytes); 693 694 /* Free and clear the buffers. */ 695 buffer_free(&stdin_buffer); 696 buffer_free(&stdout_buffer); 697 buffer_free(&stderr_buffer); 698 699 /* Close the file descriptors. */ 700 if (fdout != -1) 701 close(fdout); 702 fdout = -1; 703 fdout_eof = 1; 704 if (fderr != -1) 705 close(fderr); 706 fderr = -1; 707 fderr_eof = 1; 708 if (fdin != -1) 709 close(fdin); 710 fdin = -1; 711 712 channel_free_all(); 713 714 /* We no longer want our SIGCHLD handler to be called. */ 715 signal(SIGCHLD, SIG_DFL); 716 717 while ((wait_pid = waitpid(-1, &wait_status, 0)) < 0) 718 if (errno != EINTR) 719 packet_disconnect("wait: %.100s", strerror(errno)); 720 if (wait_pid != pid) 721 error("Strange, wait returned pid %ld, expected %ld", 722 (long)wait_pid, (long)pid); 723 724 /* Check if it exited normally. */ 725 if (WIFEXITED(wait_status)) { 726 /* Yes, normal exit. Get exit status and send it to the client. */ 727 debug("Command exited with status %d.", WEXITSTATUS(wait_status)); 728 packet_start(SSH_SMSG_EXITSTATUS); 729 packet_put_int(WEXITSTATUS(wait_status)); 730 packet_send(); 731 packet_write_wait(); 732 733 /* 734 * Wait for exit confirmation. Note that there might be 735 * other packets coming before it; however, the program has 736 * already died so we just ignore them. The client is 737 * supposed to respond with the confirmation when it receives 738 * the exit status. 739 */ 740 do { 741 type = packet_read(); 742 } 743 while (type != SSH_CMSG_EXIT_CONFIRMATION); 744 745 debug("Received exit confirmation."); 746 return; 747 } 748 /* Check if the program terminated due to a signal. */ 749 if (WIFSIGNALED(wait_status)) 750 packet_disconnect("Command terminated on signal %d.", 751 WTERMSIG(wait_status)); 752 753 /* Some weird exit cause. Just exit. */ 754 packet_disconnect("wait returned status %04x.", wait_status); 755 /* NOTREACHED */ 756 } 757 758 static void 759 collect_children(void) 760 { 761 pid_t pid; 762 sigset_t oset, nset; 763 int status; 764 765 /* block SIGCHLD while we check for dead children */ 766 sigemptyset(&nset); 767 sigaddset(&nset, SIGCHLD); 768 sigprocmask(SIG_BLOCK, &nset, &oset); 769 if (child_terminated) { 770 debug("Received SIGCHLD."); 771 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 772 (pid < 0 && errno == EINTR)) 773 if (pid > 0) 774 session_close_by_pid(pid, status); 775 child_terminated = 0; 776 } 777 sigprocmask(SIG_SETMASK, &oset, NULL); 778 } 779 780 void 781 server_loop2(Authctxt *authctxt) 782 { 783 fd_set *readset = NULL, *writeset = NULL; 784 int rekeying = 0, max_fd, nalloc = 0; 785 786 debug("Entering interactive session for SSH2."); 787 788 signal(SIGCHLD, sigchld_handler); 789 child_terminated = 0; 790 connection_in = packet_get_connection_in(); 791 connection_out = packet_get_connection_out(); 792 793 if (!use_privsep) { 794 signal(SIGTERM, sigterm_handler); 795 signal(SIGINT, sigterm_handler); 796 signal(SIGQUIT, sigterm_handler); 797 } 798 799 notify_setup(); 800 801 max_fd = MAX(connection_in, connection_out); 802 max_fd = MAX(max_fd, notify_pipe[0]); 803 804 server_init_dispatch(); 805 806 for (;;) { 807 process_buffered_input_packets(); 808 809 rekeying = (xxx_kex != NULL && !xxx_kex->done); 810 811 if (!rekeying && packet_not_very_much_data_to_write()) 812 channel_output_poll(); 813 wait_until_can_do_something(&readset, &writeset, &max_fd, 814 &nalloc, 0); 815 816 if (received_sigterm) { 817 logit("Exiting on signal %d", received_sigterm); 818 /* Clean up sessions, utmp, etc. */ 819 cleanup_exit(255); 820 } 821 822 collect_children(); 823 if (!rekeying) { 824 channel_after_select(readset, writeset); 825 if (packet_need_rekeying()) { 826 debug("need rekeying"); 827 xxx_kex->done = 0; 828 kex_send_kexinit(xxx_kex); 829 } 830 } 831 process_input(readset); 832 if (connection_closed) 833 break; 834 process_output(writeset); 835 } 836 collect_children(); 837 838 if (readset) 839 xfree(readset); 840 if (writeset) 841 xfree(writeset); 842 843 /* free all channels, no more reads and writes */ 844 channel_free_all(); 845 846 /* free remaining sessions, e.g. remove wtmp entries */ 847 session_destroy_all(NULL); 848 } 849 850 static void 851 server_input_keep_alive(int type, u_int32_t seq, void *ctxt) 852 { 853 debug("Got %d/%u for keepalive", type, seq); 854 /* 855 * reset timeout, since we got a sane answer from the client. 856 * even if this was generated by something other than 857 * the bogus CHANNEL_REQUEST we send for keepalives. 858 */ 859 keep_alive_timeouts = 0; 860 } 861 862 static void 863 server_input_stdin_data(int type, u_int32_t seq, void *ctxt) 864 { 865 char *data; 866 u_int data_len; 867 868 /* Stdin data from the client. Append it to the buffer. */ 869 /* Ignore any data if the client has closed stdin. */ 870 if (fdin == -1) 871 return; 872 data = packet_get_string(&data_len); 873 packet_check_eom(); 874 buffer_append(&stdin_buffer, data, data_len); 875 memset(data, 0, data_len); 876 xfree(data); 877 } 878 879 static void 880 server_input_eof(int type, u_int32_t seq, void *ctxt) 881 { 882 /* 883 * Eof from the client. The stdin descriptor to the 884 * program will be closed when all buffered data has 885 * drained. 886 */ 887 debug("EOF received for stdin."); 888 packet_check_eom(); 889 stdin_eof = 1; 890 } 891 892 static void 893 server_input_window_size(int type, u_int32_t seq, void *ctxt) 894 { 895 u_int row = packet_get_int(); 896 u_int col = packet_get_int(); 897 u_int xpixel = packet_get_int(); 898 u_int ypixel = packet_get_int(); 899 900 debug("Window change received."); 901 packet_check_eom(); 902 if (fdin != -1) 903 pty_change_window_size(fdin, row, col, xpixel, ypixel); 904 } 905 906 static Channel * 907 server_request_direct_tcpip(void) 908 { 909 Channel *c; 910 int sock; 911 char *target, *originator; 912 int target_port, originator_port; 913 914 target = packet_get_string(NULL); 915 target_port = packet_get_int(); 916 originator = packet_get_string(NULL); 917 originator_port = packet_get_int(); 918 packet_check_eom(); 919 920 debug("server_request_direct_tcpip: originator %s port %d, target %s port %d", 921 originator, originator_port, target, target_port); 922 923 /* XXX check permission */ 924 sock = channel_connect_to(target, target_port); 925 xfree(target); 926 xfree(originator); 927 if (sock < 0) 928 return NULL; 929 c = channel_new("direct-tcpip", SSH_CHANNEL_CONNECTING, 930 sock, sock, -1, CHAN_TCP_WINDOW_DEFAULT, 931 CHAN_TCP_PACKET_DEFAULT, 0, "direct-tcpip", 1); 932 return c; 933 } 934 935 static Channel * 936 server_request_tun(void) 937 { 938 Channel *c = NULL; 939 int mode, tun; 940 int sock; 941 942 mode = packet_get_int(); 943 switch (mode) { 944 case SSH_TUNMODE_POINTOPOINT: 945 case SSH_TUNMODE_ETHERNET: 946 break; 947 default: 948 packet_send_debug("Unsupported tunnel device mode."); 949 return NULL; 950 } 951 if ((options.permit_tun & mode) == 0) { 952 packet_send_debug("Server has rejected tunnel device " 953 "forwarding"); 954 return NULL; 955 } 956 957 tun = packet_get_int(); 958 if (forced_tun_device != -1) { 959 if (tun != SSH_TUNID_ANY && forced_tun_device != tun) 960 goto done; 961 tun = forced_tun_device; 962 } 963 sock = tun_open(tun, mode); 964 if (sock < 0) 965 goto done; 966 c = channel_new("tun", SSH_CHANNEL_OPEN, sock, sock, -1, 967 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1); 968 c->datagram = 1; 969 970 done: 971 if (c == NULL) 972 packet_send_debug("Failed to open the tunnel device."); 973 return c; 974 } 975 976 static Channel * 977 server_request_session(void) 978 { 979 Channel *c; 980 981 debug("input_session_request"); 982 packet_check_eom(); 983 /* 984 * A server session has no fd to read or write until a 985 * CHANNEL_REQUEST for a shell is made, so we set the type to 986 * SSH_CHANNEL_LARVAL. Additionally, a callback for handling all 987 * CHANNEL_REQUEST messages is registered. 988 */ 989 c = channel_new("session", SSH_CHANNEL_LARVAL, 990 -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT, 991 0, "server-session", 1); 992 if (session_open(the_authctxt, c->self) != 1) { 993 debug("session open failed, free channel %d", c->self); 994 channel_free(c); 995 return NULL; 996 } 997 channel_register_cleanup(c->self, session_close_by_channel, 0); 998 return c; 999 } 1000 1001 static void 1002 server_input_channel_open(int type, u_int32_t seq, void *ctxt) 1003 { 1004 Channel *c = NULL; 1005 char *ctype; 1006 int rchan; 1007 u_int rmaxpack, rwindow, len; 1008 1009 ctype = packet_get_string(&len); 1010 rchan = packet_get_int(); 1011 rwindow = packet_get_int(); 1012 rmaxpack = packet_get_int(); 1013 1014 debug("server_input_channel_open: ctype %s rchan %d win %d max %d", 1015 ctype, rchan, rwindow, rmaxpack); 1016 1017 if (strcmp(ctype, "session") == 0) { 1018 c = server_request_session(); 1019 } else if (strcmp(ctype, "direct-tcpip") == 0) { 1020 c = server_request_direct_tcpip(); 1021 } else if (strcmp(ctype, "tun@openssh.com") == 0) { 1022 c = server_request_tun(); 1023 } 1024 if (c != NULL) { 1025 debug("server_input_channel_open: confirm %s", ctype); 1026 c->remote_id = rchan; 1027 c->remote_window = rwindow; 1028 c->remote_maxpacket = rmaxpack; 1029 if (c->type != SSH_CHANNEL_CONNECTING) { 1030 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION); 1031 packet_put_int(c->remote_id); 1032 packet_put_int(c->self); 1033 packet_put_int(c->local_window); 1034 packet_put_int(c->local_maxpacket); 1035 packet_send(); 1036 } 1037 } else { 1038 debug("server_input_channel_open: failure %s", ctype); 1039 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE); 1040 packet_put_int(rchan); 1041 packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED); 1042 if (!(datafellows & SSH_BUG_OPENFAILURE)) { 1043 packet_put_cstring("open failed"); 1044 packet_put_cstring(""); 1045 } 1046 packet_send(); 1047 } 1048 xfree(ctype); 1049 } 1050 1051 static void 1052 server_input_global_request(int type, u_int32_t seq, void *ctxt) 1053 { 1054 char *rtype; 1055 int want_reply; 1056 int success = 0; 1057 1058 rtype = packet_get_string(NULL); 1059 want_reply = packet_get_char(); 1060 debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply); 1061 1062 /* -R style forwarding */ 1063 if (strcmp(rtype, "tcpip-forward") == 0) { 1064 struct passwd *pw; 1065 char *listen_address; 1066 u_short listen_port; 1067 1068 pw = the_authctxt->pw; 1069 if (pw == NULL || !the_authctxt->valid) 1070 fatal("server_input_global_request: no/invalid user"); 1071 listen_address = packet_get_string(NULL); 1072 listen_port = (u_short)packet_get_int(); 1073 debug("server_input_global_request: tcpip-forward listen %s port %d", 1074 listen_address, listen_port); 1075 1076 /* check permissions */ 1077 if (!options.allow_tcp_forwarding || 1078 no_port_forwarding_flag || 1079 (listen_port < IPPORT_RESERVED && pw->pw_uid != 0)) { 1080 success = 0; 1081 packet_send_debug("Server has disabled port forwarding."); 1082 } else { 1083 /* Start listening on the port */ 1084 success = channel_setup_remote_fwd_listener( 1085 listen_address, listen_port, options.gateway_ports); 1086 } 1087 xfree(listen_address); 1088 } else if (strcmp(rtype, "cancel-tcpip-forward") == 0) { 1089 char *cancel_address; 1090 u_short cancel_port; 1091 1092 cancel_address = packet_get_string(NULL); 1093 cancel_port = (u_short)packet_get_int(); 1094 debug("%s: cancel-tcpip-forward addr %s port %d", __func__, 1095 cancel_address, cancel_port); 1096 1097 success = channel_cancel_rport_listener(cancel_address, 1098 cancel_port); 1099 xfree(cancel_address); 1100 } 1101 if (want_reply) { 1102 packet_start(success ? 1103 SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE); 1104 packet_send(); 1105 packet_write_wait(); 1106 } 1107 xfree(rtype); 1108 } 1109 1110 static void 1111 server_input_channel_req(int type, u_int32_t seq, void *ctxt) 1112 { 1113 Channel *c; 1114 int id, reply, success = 0; 1115 char *rtype; 1116 1117 id = packet_get_int(); 1118 rtype = packet_get_string(NULL); 1119 reply = packet_get_char(); 1120 1121 debug("server_input_channel_req: channel %d request %s reply %d", 1122 id, rtype, reply); 1123 1124 if ((c = channel_lookup(id)) == NULL) 1125 packet_disconnect("server_input_channel_req: " 1126 "unknown channel %d", id); 1127 if (c->type == SSH_CHANNEL_LARVAL || c->type == SSH_CHANNEL_OPEN) 1128 success = session_input_channel_req(c, rtype); 1129 if (reply) { 1130 packet_start(success ? 1131 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE); 1132 packet_put_int(c->remote_id); 1133 packet_send(); 1134 } 1135 xfree(rtype); 1136 } 1137 1138 static void 1139 server_init_dispatch_20(void) 1140 { 1141 debug("server_init_dispatch_20"); 1142 dispatch_init(&dispatch_protocol_error); 1143 dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); 1144 dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data); 1145 dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); 1146 dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); 1147 dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open); 1148 dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 1149 dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 1150 dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req); 1151 dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); 1152 dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request); 1153 /* client_alive */ 1154 dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_keep_alive); 1155 dispatch_set(SSH2_MSG_REQUEST_SUCCESS, &server_input_keep_alive); 1156 dispatch_set(SSH2_MSG_REQUEST_FAILURE, &server_input_keep_alive); 1157 /* rekeying */ 1158 dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); 1159 } 1160 static void 1161 server_init_dispatch_13(void) 1162 { 1163 debug("server_init_dispatch_13"); 1164 dispatch_init(NULL); 1165 dispatch_set(SSH_CMSG_EOF, &server_input_eof); 1166 dispatch_set(SSH_CMSG_STDIN_DATA, &server_input_stdin_data); 1167 dispatch_set(SSH_CMSG_WINDOW_SIZE, &server_input_window_size); 1168 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close); 1169 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation); 1170 dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data); 1171 dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 1172 dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 1173 dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open); 1174 } 1175 static void 1176 server_init_dispatch_15(void) 1177 { 1178 server_init_dispatch_13(); 1179 debug("server_init_dispatch_15"); 1180 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof); 1181 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_oclose); 1182 } 1183 static void 1184 server_init_dispatch(void) 1185 { 1186 if (compat20) 1187 server_init_dispatch_20(); 1188 else if (compat13) 1189 server_init_dispatch_13(); 1190 else 1191 server_init_dispatch_15(); 1192 } 1193