1 /* $OpenBSD: serverloop.c,v 1.159 2009/05/28 16:50:16 andreas Exp $ */ 2 /* $FreeBSD$ */ 3 /* 4 * Author: Tatu Ylonen <ylo@cs.hut.fi> 5 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 6 * All rights reserved 7 * Server main loop for handling the interactive session. 8 * 9 * As far as I am concerned, the code I have written for this software 10 * can be used freely for any purpose. Any derived versions of this 11 * software must be clearly marked as such, and if the derived work is 12 * incompatible with the protocol description in the RFC file, it must be 13 * called by a name other than "ssh" or "Secure Shell". 14 * 15 * SSH2 support by Markus Friedl. 16 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 17 * 18 * Redistribution and use in source and binary forms, with or without 19 * modification, are permitted provided that the following conditions 20 * are met: 21 * 1. Redistributions of source code must retain the above copyright 22 * notice, this list of conditions and the following disclaimer. 23 * 2. Redistributions in binary form must reproduce the above copyright 24 * notice, this list of conditions and the following disclaimer in the 25 * documentation and/or other materials provided with the distribution. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 28 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 29 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 30 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 31 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 32 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 33 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 34 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 35 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 36 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 37 */ 38 39 #include "includes.h" 40 41 #include <sys/types.h> 42 #include <sys/param.h> 43 #include <sys/wait.h> 44 #include <sys/socket.h> 45 #ifdef HAVE_SYS_TIME_H 46 # include <sys/time.h> 47 #endif 48 49 #include <netinet/in.h> 50 51 #include <errno.h> 52 #include <fcntl.h> 53 #include <pwd.h> 54 #include <signal.h> 55 #include <string.h> 56 #include <termios.h> 57 #include <unistd.h> 58 #include <stdarg.h> 59 60 #include "openbsd-compat/sys-queue.h" 61 #include "xmalloc.h" 62 #include "packet.h" 63 #include "buffer.h" 64 #include "log.h" 65 #include "servconf.h" 66 #include "canohost.h" 67 #include "sshpty.h" 68 #include "channels.h" 69 #include "compat.h" 70 #include "ssh1.h" 71 #include "ssh2.h" 72 #include "key.h" 73 #include "cipher.h" 74 #include "kex.h" 75 #include "hostfile.h" 76 #include "auth.h" 77 #include "session.h" 78 #include "dispatch.h" 79 #include "auth-options.h" 80 #include "serverloop.h" 81 #include "misc.h" 82 #include "roaming.h" 83 84 extern ServerOptions options; 85 86 /* XXX */ 87 extern Kex *xxx_kex; 88 extern Authctxt *the_authctxt; 89 extern int use_privsep; 90 91 static Buffer stdin_buffer; /* Buffer for stdin data. */ 92 static Buffer stdout_buffer; /* Buffer for stdout data. */ 93 static Buffer stderr_buffer; /* Buffer for stderr data. */ 94 static int fdin; /* Descriptor for stdin (for writing) */ 95 static int fdout; /* Descriptor for stdout (for reading); 96 May be same number as fdin. */ 97 static int fderr; /* Descriptor for stderr. May be -1. */ 98 static long stdin_bytes = 0; /* Number of bytes written to stdin. */ 99 static long stdout_bytes = 0; /* Number of stdout bytes sent to client. */ 100 static long stderr_bytes = 0; /* Number of stderr bytes sent to client. */ 101 static long fdout_bytes = 0; /* Number of stdout bytes read from program. */ 102 static int stdin_eof = 0; /* EOF message received from client. */ 103 static int fdout_eof = 0; /* EOF encountered reading from fdout. */ 104 static int fderr_eof = 0; /* EOF encountered readung from fderr. */ 105 static int fdin_is_tty = 0; /* fdin points to a tty. */ 106 static int connection_in; /* Connection to client (input). */ 107 static int connection_out; /* Connection to client (output). */ 108 static int connection_closed = 0; /* Connection to client closed. */ 109 static u_int buffer_high; /* "Soft" max buffer size. */ 110 static int no_more_sessions = 0; /* Disallow further sessions. */ 111 112 /* 113 * This SIGCHLD kludge is used to detect when the child exits. The server 114 * will exit after that, as soon as forwarded connections have terminated. 115 */ 116 117 static volatile sig_atomic_t child_terminated = 0; /* The child has terminated. */ 118 119 /* Cleanup on signals (!use_privsep case only) */ 120 static volatile sig_atomic_t received_sigterm = 0; 121 122 /* prototypes */ 123 static void server_init_dispatch(void); 124 125 /* 126 * we write to this pipe if a SIGCHLD is caught in order to avoid 127 * the race between select() and child_terminated 128 */ 129 static int notify_pipe[2]; 130 static void 131 notify_setup(void) 132 { 133 if (pipe(notify_pipe) < 0) { 134 error("pipe(notify_pipe) failed %s", strerror(errno)); 135 } else if ((fcntl(notify_pipe[0], F_SETFD, 1) == -1) || 136 (fcntl(notify_pipe[1], F_SETFD, 1) == -1)) { 137 error("fcntl(notify_pipe, F_SETFD) failed %s", strerror(errno)); 138 close(notify_pipe[0]); 139 close(notify_pipe[1]); 140 } else { 141 set_nonblock(notify_pipe[0]); 142 set_nonblock(notify_pipe[1]); 143 return; 144 } 145 notify_pipe[0] = -1; /* read end */ 146 notify_pipe[1] = -1; /* write end */ 147 } 148 static void 149 notify_parent(void) 150 { 151 if (notify_pipe[1] != -1) 152 write(notify_pipe[1], "", 1); 153 } 154 static void 155 notify_prepare(fd_set *readset) 156 { 157 if (notify_pipe[0] != -1) 158 FD_SET(notify_pipe[0], readset); 159 } 160 static void 161 notify_done(fd_set *readset) 162 { 163 char c; 164 165 if (notify_pipe[0] != -1 && FD_ISSET(notify_pipe[0], readset)) 166 while (read(notify_pipe[0], &c, 1) != -1) 167 debug2("notify_done: reading"); 168 } 169 170 /*ARGSUSED*/ 171 static void 172 sigchld_handler(int sig) 173 { 174 int save_errno = errno; 175 child_terminated = 1; 176 #ifndef _UNICOS 177 mysignal(SIGCHLD, sigchld_handler); 178 #endif 179 notify_parent(); 180 errno = save_errno; 181 } 182 183 /*ARGSUSED*/ 184 static void 185 sigterm_handler(int sig) 186 { 187 received_sigterm = sig; 188 } 189 190 /* 191 * Make packets from buffered stderr data, and buffer it for sending 192 * to the client. 193 */ 194 static void 195 make_packets_from_stderr_data(void) 196 { 197 u_int len; 198 199 /* Send buffered stderr data to the client. */ 200 while (buffer_len(&stderr_buffer) > 0 && 201 packet_not_very_much_data_to_write()) { 202 len = buffer_len(&stderr_buffer); 203 if (packet_is_interactive()) { 204 if (len > 512) 205 len = 512; 206 } else { 207 /* Keep the packets at reasonable size. */ 208 if (len > packet_get_maxsize()) 209 len = packet_get_maxsize(); 210 } 211 packet_start(SSH_SMSG_STDERR_DATA); 212 packet_put_string(buffer_ptr(&stderr_buffer), len); 213 packet_send(); 214 buffer_consume(&stderr_buffer, len); 215 stderr_bytes += len; 216 } 217 } 218 219 /* 220 * Make packets from buffered stdout data, and buffer it for sending to the 221 * client. 222 */ 223 static void 224 make_packets_from_stdout_data(void) 225 { 226 u_int len; 227 228 /* Send buffered stdout data to the client. */ 229 while (buffer_len(&stdout_buffer) > 0 && 230 packet_not_very_much_data_to_write()) { 231 len = buffer_len(&stdout_buffer); 232 if (packet_is_interactive()) { 233 if (len > 512) 234 len = 512; 235 } else { 236 /* Keep the packets at reasonable size. */ 237 if (len > packet_get_maxsize()) 238 len = packet_get_maxsize(); 239 } 240 packet_start(SSH_SMSG_STDOUT_DATA); 241 packet_put_string(buffer_ptr(&stdout_buffer), len); 242 packet_send(); 243 buffer_consume(&stdout_buffer, len); 244 stdout_bytes += len; 245 } 246 } 247 248 static void 249 client_alive_check(void) 250 { 251 int channel_id; 252 253 /* timeout, check to see how many we have had */ 254 if (packet_inc_alive_timeouts() > options.client_alive_count_max) { 255 logit("Timeout, client not responding."); 256 cleanup_exit(255); 257 } 258 259 /* 260 * send a bogus global/channel request with "wantreply", 261 * we should get back a failure 262 */ 263 if ((channel_id = channel_find_open()) == -1) { 264 packet_start(SSH2_MSG_GLOBAL_REQUEST); 265 packet_put_cstring("keepalive@openssh.com"); 266 packet_put_char(1); /* boolean: want reply */ 267 } else { 268 channel_request_start(channel_id, "keepalive@openssh.com", 1); 269 } 270 packet_send(); 271 } 272 273 /* 274 * Sleep in select() until we can do something. This will initialize the 275 * select masks. Upon return, the masks will indicate which descriptors 276 * have data or can accept data. Optionally, a maximum time can be specified 277 * for the duration of the wait (0 = infinite). 278 */ 279 static void 280 wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp, 281 u_int *nallocp, u_int max_time_milliseconds) 282 { 283 struct timeval tv, *tvp; 284 int ret; 285 int client_alive_scheduled = 0; 286 int program_alive_scheduled = 0; 287 288 /* 289 * if using client_alive, set the max timeout accordingly, 290 * and indicate that this particular timeout was for client 291 * alive by setting the client_alive_scheduled flag. 292 * 293 * this could be randomized somewhat to make traffic 294 * analysis more difficult, but we're not doing it yet. 295 */ 296 if (compat20 && 297 max_time_milliseconds == 0 && options.client_alive_interval) { 298 client_alive_scheduled = 1; 299 max_time_milliseconds = options.client_alive_interval * 1000; 300 } 301 302 /* Allocate and update select() masks for channel descriptors. */ 303 channel_prepare_select(readsetp, writesetp, maxfdp, nallocp, 0); 304 305 if (compat20) { 306 #if 0 307 /* wrong: bad condition XXX */ 308 if (channel_not_very_much_buffered_data()) 309 #endif 310 FD_SET(connection_in, *readsetp); 311 } else { 312 /* 313 * Read packets from the client unless we have too much 314 * buffered stdin or channel data. 315 */ 316 if (buffer_len(&stdin_buffer) < buffer_high && 317 channel_not_very_much_buffered_data()) 318 FD_SET(connection_in, *readsetp); 319 /* 320 * If there is not too much data already buffered going to 321 * the client, try to get some more data from the program. 322 */ 323 if (packet_not_very_much_data_to_write()) { 324 program_alive_scheduled = child_terminated; 325 if (!fdout_eof) 326 FD_SET(fdout, *readsetp); 327 if (!fderr_eof) 328 FD_SET(fderr, *readsetp); 329 } 330 /* 331 * If we have buffered data, try to write some of that data 332 * to the program. 333 */ 334 if (fdin != -1 && buffer_len(&stdin_buffer) > 0) 335 FD_SET(fdin, *writesetp); 336 } 337 notify_prepare(*readsetp); 338 339 /* 340 * If we have buffered packet data going to the client, mark that 341 * descriptor. 342 */ 343 if (packet_have_data_to_write()) 344 FD_SET(connection_out, *writesetp); 345 346 /* 347 * If child has terminated and there is enough buffer space to read 348 * from it, then read as much as is available and exit. 349 */ 350 if (child_terminated && packet_not_very_much_data_to_write()) 351 if (max_time_milliseconds == 0 || client_alive_scheduled) 352 max_time_milliseconds = 100; 353 354 if (max_time_milliseconds == 0) 355 tvp = NULL; 356 else { 357 tv.tv_sec = max_time_milliseconds / 1000; 358 tv.tv_usec = 1000 * (max_time_milliseconds % 1000); 359 tvp = &tv; 360 } 361 362 /* Wait for something to happen, or the timeout to expire. */ 363 ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp); 364 365 if (ret == -1) { 366 memset(*readsetp, 0, *nallocp); 367 memset(*writesetp, 0, *nallocp); 368 if (errno != EINTR) 369 error("select: %.100s", strerror(errno)); 370 } else { 371 if (ret == 0 && client_alive_scheduled) 372 client_alive_check(); 373 if (!compat20 && program_alive_scheduled && fdin_is_tty) { 374 if (!fdout_eof) 375 FD_SET(fdout, *readsetp); 376 if (!fderr_eof) 377 FD_SET(fderr, *readsetp); 378 } 379 } 380 381 notify_done(*readsetp); 382 } 383 384 /* 385 * Processes input from the client and the program. Input data is stored 386 * in buffers and processed later. 387 */ 388 static void 389 process_input(fd_set *readset) 390 { 391 int len; 392 char buf[16384]; 393 394 /* Read and buffer any input data from the client. */ 395 if (FD_ISSET(connection_in, readset)) { 396 int cont = 0; 397 len = roaming_read(connection_in, buf, sizeof(buf), &cont); 398 if (len == 0) { 399 if (cont) 400 return; 401 verbose("Connection closed by %.100s", 402 get_remote_ipaddr()); 403 connection_closed = 1; 404 if (compat20) 405 return; 406 cleanup_exit(255); 407 } else if (len < 0) { 408 if (errno != EINTR && errno != EAGAIN && 409 errno != EWOULDBLOCK) { 410 verbose("Read error from remote host " 411 "%.100s: %.100s", 412 get_remote_ipaddr(), strerror(errno)); 413 cleanup_exit(255); 414 } 415 } else { 416 /* Buffer any received data. */ 417 packet_process_incoming(buf, len); 418 } 419 } 420 if (compat20) 421 return; 422 423 /* Read and buffer any available stdout data from the program. */ 424 if (!fdout_eof && FD_ISSET(fdout, readset)) { 425 errno = 0; 426 len = read(fdout, buf, sizeof(buf)); 427 if (len < 0 && (errno == EINTR || ((errno == EAGAIN || 428 errno == EWOULDBLOCK) && !child_terminated))) { 429 /* do nothing */ 430 #ifndef PTY_ZEROREAD 431 } else if (len <= 0) { 432 #else 433 } else if ((!isatty(fdout) && len <= 0) || 434 (isatty(fdout) && (len < 0 || (len == 0 && errno != 0)))) { 435 #endif 436 fdout_eof = 1; 437 } else { 438 buffer_append(&stdout_buffer, buf, len); 439 fdout_bytes += len; 440 } 441 } 442 /* Read and buffer any available stderr data from the program. */ 443 if (!fderr_eof && FD_ISSET(fderr, readset)) { 444 errno = 0; 445 len = read(fderr, buf, sizeof(buf)); 446 if (len < 0 && (errno == EINTR || ((errno == EAGAIN || 447 errno == EWOULDBLOCK) && !child_terminated))) { 448 /* do nothing */ 449 #ifndef PTY_ZEROREAD 450 } else if (len <= 0) { 451 #else 452 } else if ((!isatty(fderr) && len <= 0) || 453 (isatty(fderr) && (len < 0 || (len == 0 && errno != 0)))) { 454 #endif 455 fderr_eof = 1; 456 } else { 457 buffer_append(&stderr_buffer, buf, len); 458 } 459 } 460 } 461 462 /* 463 * Sends data from internal buffers to client program stdin. 464 */ 465 static void 466 process_output(fd_set *writeset) 467 { 468 struct termios tio; 469 u_char *data; 470 u_int dlen; 471 int len; 472 473 /* Write buffered data to program stdin. */ 474 if (!compat20 && fdin != -1 && FD_ISSET(fdin, writeset)) { 475 data = buffer_ptr(&stdin_buffer); 476 dlen = buffer_len(&stdin_buffer); 477 len = write(fdin, data, dlen); 478 if (len < 0 && 479 (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK)) { 480 /* do nothing */ 481 } else if (len <= 0) { 482 if (fdin != fdout) 483 close(fdin); 484 else 485 shutdown(fdin, SHUT_WR); /* We will no longer send. */ 486 fdin = -1; 487 } else { 488 /* Successful write. */ 489 if (fdin_is_tty && dlen >= 1 && data[0] != '\r' && 490 tcgetattr(fdin, &tio) == 0 && 491 !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) { 492 /* 493 * Simulate echo to reduce the impact of 494 * traffic analysis 495 */ 496 packet_send_ignore(len); 497 packet_send(); 498 } 499 /* Consume the data from the buffer. */ 500 buffer_consume(&stdin_buffer, len); 501 /* Update the count of bytes written to the program. */ 502 stdin_bytes += len; 503 } 504 } 505 /* Send any buffered packet data to the client. */ 506 if (FD_ISSET(connection_out, writeset)) 507 packet_write_poll(); 508 } 509 510 /* 511 * Wait until all buffered output has been sent to the client. 512 * This is used when the program terminates. 513 */ 514 static void 515 drain_output(void) 516 { 517 /* Send any buffered stdout data to the client. */ 518 if (buffer_len(&stdout_buffer) > 0) { 519 packet_start(SSH_SMSG_STDOUT_DATA); 520 packet_put_string(buffer_ptr(&stdout_buffer), 521 buffer_len(&stdout_buffer)); 522 packet_send(); 523 /* Update the count of sent bytes. */ 524 stdout_bytes += buffer_len(&stdout_buffer); 525 } 526 /* Send any buffered stderr data to the client. */ 527 if (buffer_len(&stderr_buffer) > 0) { 528 packet_start(SSH_SMSG_STDERR_DATA); 529 packet_put_string(buffer_ptr(&stderr_buffer), 530 buffer_len(&stderr_buffer)); 531 packet_send(); 532 /* Update the count of sent bytes. */ 533 stderr_bytes += buffer_len(&stderr_buffer); 534 } 535 /* Wait until all buffered data has been written to the client. */ 536 packet_write_wait(); 537 } 538 539 static void 540 process_buffered_input_packets(void) 541 { 542 dispatch_run(DISPATCH_NONBLOCK, NULL, compat20 ? xxx_kex : NULL); 543 } 544 545 /* 546 * Performs the interactive session. This handles data transmission between 547 * the client and the program. Note that the notion of stdin, stdout, and 548 * stderr in this function is sort of reversed: this function writes to 549 * stdin (of the child program), and reads from stdout and stderr (of the 550 * child program). 551 */ 552 void 553 server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg) 554 { 555 fd_set *readset = NULL, *writeset = NULL; 556 int max_fd = 0; 557 u_int nalloc = 0; 558 int wait_status; /* Status returned by wait(). */ 559 pid_t wait_pid; /* pid returned by wait(). */ 560 int waiting_termination = 0; /* Have displayed waiting close message. */ 561 u_int max_time_milliseconds; 562 u_int previous_stdout_buffer_bytes; 563 u_int stdout_buffer_bytes; 564 int type; 565 566 debug("Entering interactive session."); 567 568 /* Initialize the SIGCHLD kludge. */ 569 child_terminated = 0; 570 mysignal(SIGCHLD, sigchld_handler); 571 572 if (!use_privsep) { 573 signal(SIGTERM, sigterm_handler); 574 signal(SIGINT, sigterm_handler); 575 signal(SIGQUIT, sigterm_handler); 576 } 577 578 /* Initialize our global variables. */ 579 fdin = fdin_arg; 580 fdout = fdout_arg; 581 fderr = fderr_arg; 582 583 /* nonblocking IO */ 584 set_nonblock(fdin); 585 set_nonblock(fdout); 586 /* we don't have stderr for interactive terminal sessions, see below */ 587 if (fderr != -1) 588 set_nonblock(fderr); 589 590 if (!(datafellows & SSH_BUG_IGNOREMSG) && isatty(fdin)) 591 fdin_is_tty = 1; 592 593 connection_in = packet_get_connection_in(); 594 connection_out = packet_get_connection_out(); 595 596 notify_setup(); 597 598 previous_stdout_buffer_bytes = 0; 599 600 /* Set approximate I/O buffer size. */ 601 if (packet_is_interactive()) 602 buffer_high = 4096; 603 else 604 buffer_high = 64 * 1024; 605 606 #if 0 607 /* Initialize max_fd to the maximum of the known file descriptors. */ 608 max_fd = MAX(connection_in, connection_out); 609 max_fd = MAX(max_fd, fdin); 610 max_fd = MAX(max_fd, fdout); 611 if (fderr != -1) 612 max_fd = MAX(max_fd, fderr); 613 #endif 614 615 /* Initialize Initialize buffers. */ 616 buffer_init(&stdin_buffer); 617 buffer_init(&stdout_buffer); 618 buffer_init(&stderr_buffer); 619 620 /* 621 * If we have no separate fderr (which is the case when we have a pty 622 * - there we cannot make difference between data sent to stdout and 623 * stderr), indicate that we have seen an EOF from stderr. This way 624 * we don't need to check the descriptor everywhere. 625 */ 626 if (fderr == -1) 627 fderr_eof = 1; 628 629 server_init_dispatch(); 630 631 /* Main loop of the server for the interactive session mode. */ 632 for (;;) { 633 634 /* Process buffered packets from the client. */ 635 process_buffered_input_packets(); 636 637 /* 638 * If we have received eof, and there is no more pending 639 * input data, cause a real eof by closing fdin. 640 */ 641 if (stdin_eof && fdin != -1 && buffer_len(&stdin_buffer) == 0) { 642 if (fdin != fdout) 643 close(fdin); 644 else 645 shutdown(fdin, SHUT_WR); /* We will no longer send. */ 646 fdin = -1; 647 } 648 /* Make packets from buffered stderr data to send to the client. */ 649 make_packets_from_stderr_data(); 650 651 /* 652 * Make packets from buffered stdout data to send to the 653 * client. If there is very little to send, this arranges to 654 * not send them now, but to wait a short while to see if we 655 * are getting more data. This is necessary, as some systems 656 * wake up readers from a pty after each separate character. 657 */ 658 max_time_milliseconds = 0; 659 stdout_buffer_bytes = buffer_len(&stdout_buffer); 660 if (stdout_buffer_bytes != 0 && stdout_buffer_bytes < 256 && 661 stdout_buffer_bytes != previous_stdout_buffer_bytes) { 662 /* try again after a while */ 663 max_time_milliseconds = 10; 664 } else { 665 /* Send it now. */ 666 make_packets_from_stdout_data(); 667 } 668 previous_stdout_buffer_bytes = buffer_len(&stdout_buffer); 669 670 /* Send channel data to the client. */ 671 if (packet_not_very_much_data_to_write()) 672 channel_output_poll(); 673 674 /* 675 * Bail out of the loop if the program has closed its output 676 * descriptors, and we have no more data to send to the 677 * client, and there is no pending buffered data. 678 */ 679 if (fdout_eof && fderr_eof && !packet_have_data_to_write() && 680 buffer_len(&stdout_buffer) == 0 && buffer_len(&stderr_buffer) == 0) { 681 if (!channel_still_open()) 682 break; 683 if (!waiting_termination) { 684 const char *s = "Waiting for forwarded connections to terminate...\r\n"; 685 char *cp; 686 waiting_termination = 1; 687 buffer_append(&stderr_buffer, s, strlen(s)); 688 689 /* Display list of open channels. */ 690 cp = channel_open_message(); 691 buffer_append(&stderr_buffer, cp, strlen(cp)); 692 xfree(cp); 693 } 694 } 695 max_fd = MAX(connection_in, connection_out); 696 max_fd = MAX(max_fd, fdin); 697 max_fd = MAX(max_fd, fdout); 698 max_fd = MAX(max_fd, fderr); 699 max_fd = MAX(max_fd, notify_pipe[0]); 700 701 /* Sleep in select() until we can do something. */ 702 wait_until_can_do_something(&readset, &writeset, &max_fd, 703 &nalloc, max_time_milliseconds); 704 705 if (received_sigterm) { 706 logit("Exiting on signal %d", received_sigterm); 707 /* Clean up sessions, utmp, etc. */ 708 cleanup_exit(255); 709 } 710 711 /* Process any channel events. */ 712 channel_after_select(readset, writeset); 713 714 /* Process input from the client and from program stdout/stderr. */ 715 process_input(readset); 716 717 /* Process output to the client and to program stdin. */ 718 process_output(writeset); 719 } 720 if (readset) 721 xfree(readset); 722 if (writeset) 723 xfree(writeset); 724 725 /* Cleanup and termination code. */ 726 727 /* Wait until all output has been sent to the client. */ 728 drain_output(); 729 730 debug("End of interactive session; stdin %ld, stdout (read %ld, " "sent %ld), stderr %ld bytes.", 731 stdin_bytes, fdout_bytes, stdout_bytes, stderr_bytes); 732 733 /* Free and clear the buffers. */ 734 buffer_free(&stdin_buffer); 735 buffer_free(&stdout_buffer); 736 buffer_free(&stderr_buffer); 737 738 /* Close the file descriptors. */ 739 if (fdout != -1) 740 close(fdout); 741 fdout = -1; 742 fdout_eof = 1; 743 if (fderr != -1) 744 close(fderr); 745 fderr = -1; 746 fderr_eof = 1; 747 if (fdin != -1) 748 close(fdin); 749 fdin = -1; 750 751 channel_free_all(); 752 753 /* We no longer want our SIGCHLD handler to be called. */ 754 mysignal(SIGCHLD, SIG_DFL); 755 756 while ((wait_pid = waitpid(-1, &wait_status, 0)) < 0) 757 if (errno != EINTR) 758 packet_disconnect("wait: %.100s", strerror(errno)); 759 if (wait_pid != pid) 760 error("Strange, wait returned pid %ld, expected %ld", 761 (long)wait_pid, (long)pid); 762 763 /* Check if it exited normally. */ 764 if (WIFEXITED(wait_status)) { 765 /* Yes, normal exit. Get exit status and send it to the client. */ 766 debug("Command exited with status %d.", WEXITSTATUS(wait_status)); 767 packet_start(SSH_SMSG_EXITSTATUS); 768 packet_put_int(WEXITSTATUS(wait_status)); 769 packet_send(); 770 packet_write_wait(); 771 772 /* 773 * Wait for exit confirmation. Note that there might be 774 * other packets coming before it; however, the program has 775 * already died so we just ignore them. The client is 776 * supposed to respond with the confirmation when it receives 777 * the exit status. 778 */ 779 do { 780 type = packet_read(); 781 } 782 while (type != SSH_CMSG_EXIT_CONFIRMATION); 783 784 debug("Received exit confirmation."); 785 return; 786 } 787 /* Check if the program terminated due to a signal. */ 788 if (WIFSIGNALED(wait_status)) 789 packet_disconnect("Command terminated on signal %d.", 790 WTERMSIG(wait_status)); 791 792 /* Some weird exit cause. Just exit. */ 793 packet_disconnect("wait returned status %04x.", wait_status); 794 /* NOTREACHED */ 795 } 796 797 static void 798 collect_children(void) 799 { 800 pid_t pid; 801 sigset_t oset, nset; 802 int status; 803 804 /* block SIGCHLD while we check for dead children */ 805 sigemptyset(&nset); 806 sigaddset(&nset, SIGCHLD); 807 sigprocmask(SIG_BLOCK, &nset, &oset); 808 if (child_terminated) { 809 debug("Received SIGCHLD."); 810 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 811 (pid < 0 && errno == EINTR)) 812 if (pid > 0) 813 session_close_by_pid(pid, status); 814 child_terminated = 0; 815 } 816 sigprocmask(SIG_SETMASK, &oset, NULL); 817 } 818 819 void 820 server_loop2(Authctxt *authctxt) 821 { 822 fd_set *readset = NULL, *writeset = NULL; 823 int rekeying = 0, max_fd, nalloc = 0; 824 825 debug("Entering interactive session for SSH2."); 826 827 mysignal(SIGCHLD, sigchld_handler); 828 child_terminated = 0; 829 connection_in = packet_get_connection_in(); 830 connection_out = packet_get_connection_out(); 831 832 if (!use_privsep) { 833 signal(SIGTERM, sigterm_handler); 834 signal(SIGINT, sigterm_handler); 835 signal(SIGQUIT, sigterm_handler); 836 } 837 838 notify_setup(); 839 840 max_fd = MAX(connection_in, connection_out); 841 max_fd = MAX(max_fd, notify_pipe[0]); 842 843 server_init_dispatch(); 844 845 for (;;) { 846 process_buffered_input_packets(); 847 848 rekeying = (xxx_kex != NULL && !xxx_kex->done); 849 850 if (!rekeying && packet_not_very_much_data_to_write()) 851 channel_output_poll(); 852 wait_until_can_do_something(&readset, &writeset, &max_fd, 853 &nalloc, 0); 854 855 if (received_sigterm) { 856 logit("Exiting on signal %d", received_sigterm); 857 /* Clean up sessions, utmp, etc. */ 858 cleanup_exit(255); 859 } 860 861 collect_children(); 862 if (!rekeying) { 863 channel_after_select(readset, writeset); 864 if (packet_need_rekeying()) { 865 debug("need rekeying"); 866 xxx_kex->done = 0; 867 kex_send_kexinit(xxx_kex); 868 } 869 } 870 process_input(readset); 871 if (connection_closed) 872 break; 873 process_output(writeset); 874 } 875 collect_children(); 876 877 if (readset) 878 xfree(readset); 879 if (writeset) 880 xfree(writeset); 881 882 /* free all channels, no more reads and writes */ 883 channel_free_all(); 884 885 /* free remaining sessions, e.g. remove wtmp entries */ 886 session_destroy_all(NULL); 887 } 888 889 static void 890 server_input_keep_alive(int type, u_int32_t seq, void *ctxt) 891 { 892 debug("Got %d/%u for keepalive", type, seq); 893 /* 894 * reset timeout, since we got a sane answer from the client. 895 * even if this was generated by something other than 896 * the bogus CHANNEL_REQUEST we send for keepalives. 897 */ 898 packet_set_alive_timeouts(0); 899 } 900 901 static void 902 server_input_stdin_data(int type, u_int32_t seq, void *ctxt) 903 { 904 char *data; 905 u_int data_len; 906 907 /* Stdin data from the client. Append it to the buffer. */ 908 /* Ignore any data if the client has closed stdin. */ 909 if (fdin == -1) 910 return; 911 data = packet_get_string(&data_len); 912 packet_check_eom(); 913 buffer_append(&stdin_buffer, data, data_len); 914 memset(data, 0, data_len); 915 xfree(data); 916 } 917 918 static void 919 server_input_eof(int type, u_int32_t seq, void *ctxt) 920 { 921 /* 922 * Eof from the client. The stdin descriptor to the 923 * program will be closed when all buffered data has 924 * drained. 925 */ 926 debug("EOF received for stdin."); 927 packet_check_eom(); 928 stdin_eof = 1; 929 } 930 931 static void 932 server_input_window_size(int type, u_int32_t seq, void *ctxt) 933 { 934 u_int row = packet_get_int(); 935 u_int col = packet_get_int(); 936 u_int xpixel = packet_get_int(); 937 u_int ypixel = packet_get_int(); 938 939 debug("Window change received."); 940 packet_check_eom(); 941 if (fdin != -1) 942 pty_change_window_size(fdin, row, col, xpixel, ypixel); 943 } 944 945 static Channel * 946 server_request_direct_tcpip(void) 947 { 948 Channel *c; 949 char *target, *originator; 950 u_short target_port, originator_port; 951 952 target = packet_get_string(NULL); 953 target_port = packet_get_int(); 954 originator = packet_get_string(NULL); 955 originator_port = packet_get_int(); 956 packet_check_eom(); 957 958 debug("server_request_direct_tcpip: originator %s port %d, target %s " 959 "port %d", originator, originator_port, target, target_port); 960 961 /* XXX check permission */ 962 c = channel_connect_to(target, target_port, 963 "direct-tcpip", "direct-tcpip"); 964 965 xfree(originator); 966 xfree(target); 967 968 return c; 969 } 970 971 static Channel * 972 server_request_tun(void) 973 { 974 Channel *c = NULL; 975 int mode, tun; 976 int sock; 977 978 mode = packet_get_int(); 979 switch (mode) { 980 case SSH_TUNMODE_POINTOPOINT: 981 case SSH_TUNMODE_ETHERNET: 982 break; 983 default: 984 packet_send_debug("Unsupported tunnel device mode."); 985 return NULL; 986 } 987 if ((options.permit_tun & mode) == 0) { 988 packet_send_debug("Server has rejected tunnel device " 989 "forwarding"); 990 return NULL; 991 } 992 993 tun = packet_get_int(); 994 if (forced_tun_device != -1) { 995 if (tun != SSH_TUNID_ANY && forced_tun_device != tun) 996 goto done; 997 tun = forced_tun_device; 998 } 999 sock = tun_open(tun, mode); 1000 if (sock < 0) 1001 goto done; 1002 if (options.hpn_disabled) 1003 c = channel_new("tun", SSH_CHANNEL_OPEN, sock, sock, -1, 1004 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, 1005 "tun", 1); 1006 else 1007 c = channel_new("tun", SSH_CHANNEL_OPEN, sock, sock, -1, 1008 options.hpn_buffer_size, CHAN_TCP_PACKET_DEFAULT, 0, 1009 "tun", 1); 1010 c->datagram = 1; 1011 #if defined(SSH_TUN_FILTER) 1012 if (mode == SSH_TUNMODE_POINTOPOINT) 1013 channel_register_filter(c->self, sys_tun_infilter, 1014 sys_tun_outfilter, NULL, NULL); 1015 #endif 1016 1017 done: 1018 if (c == NULL) 1019 packet_send_debug("Failed to open the tunnel device."); 1020 return c; 1021 } 1022 1023 static Channel * 1024 server_request_session(void) 1025 { 1026 Channel *c; 1027 1028 debug("input_session_request"); 1029 packet_check_eom(); 1030 1031 if (no_more_sessions) { 1032 packet_disconnect("Possible attack: attempt to open a session " 1033 "after additional sessions disabled"); 1034 } 1035 1036 /* 1037 * A server session has no fd to read or write until a 1038 * CHANNEL_REQUEST for a shell is made, so we set the type to 1039 * SSH_CHANNEL_LARVAL. Additionally, a callback for handling all 1040 * CHANNEL_REQUEST messages is registered. 1041 */ 1042 c = channel_new("session", SSH_CHANNEL_LARVAL, 1043 -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT, 1044 0, "server-session", 1); 1045 if (!options.hpn_disabled && options.tcp_rcv_buf_poll) 1046 c->dynamic_window = 1; 1047 if (session_open(the_authctxt, c->self) != 1) { 1048 debug("session open failed, free channel %d", c->self); 1049 channel_free(c); 1050 return NULL; 1051 } 1052 channel_register_cleanup(c->self, session_close_by_channel, 0); 1053 return c; 1054 } 1055 1056 static void 1057 server_input_channel_open(int type, u_int32_t seq, void *ctxt) 1058 { 1059 Channel *c = NULL; 1060 char *ctype; 1061 int rchan; 1062 u_int rmaxpack, rwindow, len; 1063 1064 ctype = packet_get_string(&len); 1065 rchan = packet_get_int(); 1066 rwindow = packet_get_int(); 1067 rmaxpack = packet_get_int(); 1068 1069 debug("server_input_channel_open: ctype %s rchan %d win %d max %d", 1070 ctype, rchan, rwindow, rmaxpack); 1071 1072 if (strcmp(ctype, "session") == 0) { 1073 c = server_request_session(); 1074 } else if (strcmp(ctype, "direct-tcpip") == 0) { 1075 c = server_request_direct_tcpip(); 1076 } else if (strcmp(ctype, "tun@openssh.com") == 0) { 1077 c = server_request_tun(); 1078 } 1079 if (c != NULL) { 1080 debug("server_input_channel_open: confirm %s", ctype); 1081 c->remote_id = rchan; 1082 c->remote_window = rwindow; 1083 c->remote_maxpacket = rmaxpack; 1084 if (c->type != SSH_CHANNEL_CONNECTING) { 1085 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION); 1086 packet_put_int(c->remote_id); 1087 packet_put_int(c->self); 1088 packet_put_int(c->local_window); 1089 packet_put_int(c->local_maxpacket); 1090 packet_send(); 1091 } 1092 } else { 1093 debug("server_input_channel_open: failure %s", ctype); 1094 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE); 1095 packet_put_int(rchan); 1096 packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED); 1097 if (!(datafellows & SSH_BUG_OPENFAILURE)) { 1098 packet_put_cstring("open failed"); 1099 packet_put_cstring(""); 1100 } 1101 packet_send(); 1102 } 1103 xfree(ctype); 1104 } 1105 1106 static void 1107 server_input_global_request(int type, u_int32_t seq, void *ctxt) 1108 { 1109 char *rtype; 1110 int want_reply; 1111 int success = 0, allocated_listen_port = 0; 1112 1113 rtype = packet_get_string(NULL); 1114 want_reply = packet_get_char(); 1115 debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply); 1116 1117 /* -R style forwarding */ 1118 if (strcmp(rtype, "tcpip-forward") == 0) { 1119 struct passwd *pw; 1120 char *listen_address; 1121 u_short listen_port; 1122 1123 pw = the_authctxt->pw; 1124 if (pw == NULL || !the_authctxt->valid) 1125 fatal("server_input_global_request: no/invalid user"); 1126 listen_address = packet_get_string(NULL); 1127 listen_port = (u_short)packet_get_int(); 1128 debug("server_input_global_request: tcpip-forward listen %s port %d", 1129 listen_address, listen_port); 1130 1131 /* check permissions */ 1132 if (!options.allow_tcp_forwarding || 1133 no_port_forwarding_flag || 1134 (!want_reply && listen_port == 0) 1135 #ifndef NO_IPPORT_RESERVED_CONCEPT 1136 || (listen_port != 0 && listen_port < IPPORT_RESERVED && 1137 pw->pw_uid != 0) 1138 #endif 1139 ) { 1140 success = 0; 1141 packet_send_debug("Server has disabled port forwarding."); 1142 } else { 1143 /* Start listening on the port */ 1144 success = channel_setup_remote_fwd_listener( 1145 listen_address, listen_port, 1146 &allocated_listen_port, options.gateway_ports); 1147 } 1148 xfree(listen_address); 1149 } else if (strcmp(rtype, "cancel-tcpip-forward") == 0) { 1150 char *cancel_address; 1151 u_short cancel_port; 1152 1153 cancel_address = packet_get_string(NULL); 1154 cancel_port = (u_short)packet_get_int(); 1155 debug("%s: cancel-tcpip-forward addr %s port %d", __func__, 1156 cancel_address, cancel_port); 1157 1158 success = channel_cancel_rport_listener(cancel_address, 1159 cancel_port); 1160 xfree(cancel_address); 1161 } else if (strcmp(rtype, "no-more-sessions@openssh.com") == 0) { 1162 no_more_sessions = 1; 1163 success = 1; 1164 } 1165 if (want_reply) { 1166 packet_start(success ? 1167 SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE); 1168 if (success && allocated_listen_port > 0) 1169 packet_put_int(allocated_listen_port); 1170 packet_send(); 1171 packet_write_wait(); 1172 } 1173 xfree(rtype); 1174 } 1175 1176 static void 1177 server_input_channel_req(int type, u_int32_t seq, void *ctxt) 1178 { 1179 Channel *c; 1180 int id, reply, success = 0; 1181 char *rtype; 1182 1183 id = packet_get_int(); 1184 rtype = packet_get_string(NULL); 1185 reply = packet_get_char(); 1186 1187 debug("server_input_channel_req: channel %d request %s reply %d", 1188 id, rtype, reply); 1189 1190 if ((c = channel_lookup(id)) == NULL) 1191 packet_disconnect("server_input_channel_req: " 1192 "unknown channel %d", id); 1193 if (!strcmp(rtype, "eow@openssh.com")) { 1194 packet_check_eom(); 1195 chan_rcvd_eow(c); 1196 } else if ((c->type == SSH_CHANNEL_LARVAL || 1197 c->type == SSH_CHANNEL_OPEN) && strcmp(c->ctype, "session") == 0) 1198 success = session_input_channel_req(c, rtype); 1199 if (reply) { 1200 packet_start(success ? 1201 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE); 1202 packet_put_int(c->remote_id); 1203 packet_send(); 1204 } 1205 xfree(rtype); 1206 } 1207 1208 static void 1209 server_init_dispatch_20(void) 1210 { 1211 debug("server_init_dispatch_20"); 1212 dispatch_init(&dispatch_protocol_error); 1213 dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); 1214 dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data); 1215 dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); 1216 dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); 1217 dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open); 1218 dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 1219 dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 1220 dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req); 1221 dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); 1222 dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request); 1223 /* client_alive */ 1224 dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &server_input_keep_alive); 1225 dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_keep_alive); 1226 dispatch_set(SSH2_MSG_REQUEST_SUCCESS, &server_input_keep_alive); 1227 dispatch_set(SSH2_MSG_REQUEST_FAILURE, &server_input_keep_alive); 1228 /* rekeying */ 1229 dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); 1230 } 1231 static void 1232 server_init_dispatch_13(void) 1233 { 1234 debug("server_init_dispatch_13"); 1235 dispatch_init(NULL); 1236 dispatch_set(SSH_CMSG_EOF, &server_input_eof); 1237 dispatch_set(SSH_CMSG_STDIN_DATA, &server_input_stdin_data); 1238 dispatch_set(SSH_CMSG_WINDOW_SIZE, &server_input_window_size); 1239 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close); 1240 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation); 1241 dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data); 1242 dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 1243 dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 1244 dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open); 1245 } 1246 static void 1247 server_init_dispatch_15(void) 1248 { 1249 server_init_dispatch_13(); 1250 debug("server_init_dispatch_15"); 1251 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof); 1252 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_oclose); 1253 } 1254 static void 1255 server_init_dispatch(void) 1256 { 1257 if (compat20) 1258 server_init_dispatch_20(); 1259 else if (compat13) 1260 server_init_dispatch_13(); 1261 else 1262 server_init_dispatch_15(); 1263 } 1264