1 /* $OpenBSD: serverloop.c,v 1.159 2009/05/28 16:50:16 andreas 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 "includes.h" 39 40 #include <sys/types.h> 41 #include <sys/param.h> 42 #include <sys/wait.h> 43 #include <sys/socket.h> 44 #ifdef HAVE_SYS_TIME_H 45 # include <sys/time.h> 46 #endif 47 48 #include <netinet/in.h> 49 50 #include <errno.h> 51 #include <fcntl.h> 52 #include <pwd.h> 53 #include <signal.h> 54 #include <string.h> 55 #include <termios.h> 56 #include <unistd.h> 57 #include <stdarg.h> 58 59 #include "openbsd-compat/sys-queue.h" 60 #include "xmalloc.h" 61 #include "packet.h" 62 #include "buffer.h" 63 #include "log.h" 64 #include "servconf.h" 65 #include "canohost.h" 66 #include "sshpty.h" 67 #include "channels.h" 68 #include "compat.h" 69 #include "ssh1.h" 70 #include "ssh2.h" 71 #include "key.h" 72 #include "cipher.h" 73 #include "kex.h" 74 #include "hostfile.h" 75 #include "auth.h" 76 #include "session.h" 77 #include "dispatch.h" 78 #include "auth-options.h" 79 #include "serverloop.h" 80 #include "misc.h" 81 #include "roaming.h" 82 83 extern ServerOptions options; 84 85 /* XXX */ 86 extern Kex *xxx_kex; 87 extern Authctxt *the_authctxt; 88 extern int use_privsep; 89 90 static Buffer stdin_buffer; /* Buffer for stdin data. */ 91 static Buffer stdout_buffer; /* Buffer for stdout data. */ 92 static Buffer stderr_buffer; /* Buffer for stderr data. */ 93 static int fdin; /* Descriptor for stdin (for writing) */ 94 static int fdout; /* Descriptor for stdout (for reading); 95 May be same number as fdin. */ 96 static int fderr; /* Descriptor for stderr. May be -1. */ 97 static u_long stdin_bytes = 0; /* Number of bytes written to stdin. */ 98 static u_long stdout_bytes = 0; /* Number of stdout bytes sent to client. */ 99 static u_long stderr_bytes = 0; /* Number of stderr bytes sent to client. */ 100 static u_long fdout_bytes = 0; /* Number of stdout bytes read from program. */ 101 static int stdin_eof = 0; /* EOF message received from client. */ 102 static int fdout_eof = 0; /* EOF encountered reading from fdout. */ 103 static int fderr_eof = 0; /* EOF encountered readung from fderr. */ 104 static int fdin_is_tty = 0; /* fdin points to a tty. */ 105 static int connection_in; /* Connection to client (input). */ 106 static int connection_out; /* Connection to client (output). */ 107 static int connection_closed = 0; /* Connection to client closed. */ 108 static u_int buffer_high; /* "Soft" max buffer size. */ 109 static int no_more_sessions = 0; /* Disallow further sessions. */ 110 111 /* 112 * This SIGCHLD kludge is used to detect when the child exits. The server 113 * will exit after that, as soon as forwarded connections have terminated. 114 */ 115 116 static volatile sig_atomic_t child_terminated = 0; /* The child has terminated. */ 117 118 /* Cleanup on signals (!use_privsep case only) */ 119 static volatile sig_atomic_t received_sigterm = 0; 120 121 /* prototypes */ 122 static void server_init_dispatch(void); 123 124 /* 125 * Returns current time in seconds from Jan 1, 1970 with the maximum 126 * available resolution. 127 */ 128 129 static double 130 get_current_time(void) 131 { 132 struct timeval tv; 133 gettimeofday(&tv, NULL); 134 return (double) tv.tv_sec + (double) tv.tv_usec / 1000000.0; 135 } 136 137 138 /* 139 * we write to this pipe if a SIGCHLD is caught in order to avoid 140 * the race between select() and child_terminated 141 */ 142 static int notify_pipe[2]; 143 static void 144 notify_setup(void) 145 { 146 if (pipe(notify_pipe) < 0) { 147 error("pipe(notify_pipe) failed %s", strerror(errno)); 148 } else if ((fcntl(notify_pipe[0], F_SETFD, 1) == -1) || 149 (fcntl(notify_pipe[1], F_SETFD, 1) == -1)) { 150 error("fcntl(notify_pipe, F_SETFD) failed %s", strerror(errno)); 151 close(notify_pipe[0]); 152 close(notify_pipe[1]); 153 } else { 154 set_nonblock(notify_pipe[0]); 155 set_nonblock(notify_pipe[1]); 156 return; 157 } 158 notify_pipe[0] = -1; /* read end */ 159 notify_pipe[1] = -1; /* write end */ 160 } 161 static void 162 notify_parent(void) 163 { 164 if (notify_pipe[1] != -1) 165 write(notify_pipe[1], "", 1); 166 } 167 static void 168 notify_prepare(fd_set *readset) 169 { 170 if (notify_pipe[0] != -1) 171 FD_SET(notify_pipe[0], readset); 172 } 173 static void 174 notify_done(fd_set *readset) 175 { 176 char c; 177 178 if (notify_pipe[0] != -1 && FD_ISSET(notify_pipe[0], readset)) 179 while (read(notify_pipe[0], &c, 1) != -1) 180 debug2("notify_done: reading"); 181 } 182 183 /*ARGSUSED*/ 184 static void 185 sigchld_handler(int sig) 186 { 187 int save_errno = errno; 188 child_terminated = 1; 189 #ifndef _UNICOS 190 mysignal(SIGCHLD, sigchld_handler); 191 #endif 192 notify_parent(); 193 errno = save_errno; 194 } 195 196 /*ARGSUSED*/ 197 static void 198 sigterm_handler(int sig) 199 { 200 received_sigterm = sig; 201 } 202 203 /* 204 * Make packets from buffered stderr data, and buffer it for sending 205 * to the client. 206 */ 207 static void 208 make_packets_from_stderr_data(void) 209 { 210 u_int len; 211 212 /* Send buffered stderr data to the client. */ 213 while (buffer_len(&stderr_buffer) > 0 && 214 packet_not_very_much_data_to_write()) { 215 len = buffer_len(&stderr_buffer); 216 if (packet_is_interactive()) { 217 if (len > 512) 218 len = 512; 219 } else { 220 /* Keep the packets at reasonable size. */ 221 if (len > packet_get_maxsize()) 222 len = packet_get_maxsize(); 223 } 224 packet_start(SSH_SMSG_STDERR_DATA); 225 packet_put_string(buffer_ptr(&stderr_buffer), len); 226 packet_send(); 227 buffer_consume(&stderr_buffer, len); 228 stderr_bytes += len; 229 } 230 } 231 232 /* 233 * Make packets from buffered stdout data, and buffer it for sending to the 234 * client. 235 */ 236 static void 237 make_packets_from_stdout_data(void) 238 { 239 u_int len; 240 241 /* Send buffered stdout data to the client. */ 242 while (buffer_len(&stdout_buffer) > 0 && 243 packet_not_very_much_data_to_write()) { 244 len = buffer_len(&stdout_buffer); 245 if (packet_is_interactive()) { 246 if (len > 512) 247 len = 512; 248 } else { 249 /* Keep the packets at reasonable size. */ 250 if (len > packet_get_maxsize()) 251 len = packet_get_maxsize(); 252 } 253 packet_start(SSH_SMSG_STDOUT_DATA); 254 packet_put_string(buffer_ptr(&stdout_buffer), len); 255 packet_send(); 256 buffer_consume(&stdout_buffer, len); 257 stdout_bytes += len; 258 } 259 } 260 261 static void 262 client_alive_check(void) 263 { 264 int channel_id; 265 266 /* timeout, check to see how many we have had */ 267 if (packet_inc_alive_timeouts() > options.client_alive_count_max) { 268 logit("Timeout, client not responding."); 269 cleanup_exit(255); 270 } 271 272 /* 273 * send a bogus global/channel request with "wantreply", 274 * we should get back a failure 275 */ 276 if ((channel_id = channel_find_open()) == -1) { 277 packet_start(SSH2_MSG_GLOBAL_REQUEST); 278 packet_put_cstring("keepalive@openssh.com"); 279 packet_put_char(1); /* boolean: want reply */ 280 } else { 281 channel_request_start(channel_id, "keepalive@openssh.com", 1); 282 } 283 packet_send(); 284 } 285 286 /* 287 * Sleep in select() until we can do something. This will initialize the 288 * select masks. Upon return, the masks will indicate which descriptors 289 * have data or can accept data. Optionally, a maximum time can be specified 290 * for the duration of the wait (0 = infinite). 291 */ 292 static void 293 wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp, 294 u_int *nallocp, u_int max_time_milliseconds) 295 { 296 struct timeval tv, *tvp; 297 int ret; 298 int client_alive_scheduled = 0; 299 int program_alive_scheduled = 0; 300 301 /* 302 * if using client_alive, set the max timeout accordingly, 303 * and indicate that this particular timeout was for client 304 * alive by setting the client_alive_scheduled flag. 305 * 306 * this could be randomized somewhat to make traffic 307 * analysis more difficult, but we're not doing it yet. 308 */ 309 if (compat20 && 310 max_time_milliseconds == 0 && options.client_alive_interval) { 311 client_alive_scheduled = 1; 312 max_time_milliseconds = options.client_alive_interval * 1000; 313 } 314 315 /* Allocate and update select() masks for channel descriptors. */ 316 channel_prepare_select(readsetp, writesetp, maxfdp, nallocp, 0); 317 318 if (compat20) { 319 #if 0 320 /* wrong: bad condition XXX */ 321 if (channel_not_very_much_buffered_data()) 322 #endif 323 FD_SET(connection_in, *readsetp); 324 } else { 325 /* 326 * Read packets from the client unless we have too much 327 * buffered stdin or channel data. 328 */ 329 if (buffer_len(&stdin_buffer) < buffer_high && 330 channel_not_very_much_buffered_data()) 331 FD_SET(connection_in, *readsetp); 332 /* 333 * If there is not too much data already buffered going to 334 * the client, try to get some more data from the program. 335 */ 336 if (packet_not_very_much_data_to_write()) { 337 program_alive_scheduled = child_terminated; 338 if (!fdout_eof) 339 FD_SET(fdout, *readsetp); 340 if (!fderr_eof) 341 FD_SET(fderr, *readsetp); 342 } 343 /* 344 * If we have buffered data, try to write some of that data 345 * to the program. 346 */ 347 if (fdin != -1 && buffer_len(&stdin_buffer) > 0) 348 FD_SET(fdin, *writesetp); 349 } 350 notify_prepare(*readsetp); 351 352 /* 353 * If we have buffered packet data going to the client, mark that 354 * descriptor. 355 */ 356 if (packet_have_data_to_write()) 357 FD_SET(connection_out, *writesetp); 358 359 /* 360 * If child has terminated and there is enough buffer space to read 361 * from it, then read as much as is available and exit. 362 */ 363 if (child_terminated && packet_not_very_much_data_to_write()) 364 if (max_time_milliseconds == 0 || client_alive_scheduled) 365 max_time_milliseconds = 100; 366 367 if (max_time_milliseconds == 0) 368 tvp = NULL; 369 else { 370 tv.tv_sec = max_time_milliseconds / 1000; 371 tv.tv_usec = 1000 * (max_time_milliseconds % 1000); 372 tvp = &tv; 373 } 374 375 /* Wait for something to happen, or the timeout to expire. */ 376 ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp); 377 378 if (ret == -1) { 379 memset(*readsetp, 0, *nallocp); 380 memset(*writesetp, 0, *nallocp); 381 if (errno != EINTR) 382 error("select: %.100s", strerror(errno)); 383 } else { 384 if (ret == 0 && client_alive_scheduled) 385 client_alive_check(); 386 if (!compat20 && program_alive_scheduled && fdin_is_tty) { 387 if (!fdout_eof) 388 FD_SET(fdout, *readsetp); 389 if (!fderr_eof) 390 FD_SET(fderr, *readsetp); 391 } 392 } 393 394 notify_done(*readsetp); 395 } 396 397 /* 398 * Processes input from the client and the program. Input data is stored 399 * in buffers and processed later. 400 */ 401 static void 402 process_input(fd_set *readset) 403 { 404 int len; 405 char buf[16384]; 406 407 /* Read and buffer any input data from the client. */ 408 if (FD_ISSET(connection_in, readset)) { 409 int cont = 0; 410 len = roaming_read(connection_in, buf, sizeof(buf), &cont); 411 if (len == 0) { 412 if (cont) 413 return; 414 verbose("Connection closed by %.100s", 415 get_remote_ipaddr()); 416 connection_closed = 1; 417 if (compat20) 418 return; 419 cleanup_exit(255); 420 } else if (len < 0) { 421 if (errno != EINTR && errno != EAGAIN && 422 errno != EWOULDBLOCK) { 423 verbose("Read error from remote host " 424 "%.100s: %.100s", 425 get_remote_ipaddr(), strerror(errno)); 426 cleanup_exit(255); 427 } 428 } else { 429 /* Buffer any received data. */ 430 packet_process_incoming(buf, len); 431 fdout_bytes += len; 432 } 433 } 434 if (compat20) 435 return; 436 437 /* Read and buffer any available stdout data from the program. */ 438 if (!fdout_eof && FD_ISSET(fdout, readset)) { 439 errno = 0; 440 len = read(fdout, buf, sizeof(buf)); 441 if (len < 0 && (errno == EINTR || ((errno == EAGAIN || 442 errno == EWOULDBLOCK) && !child_terminated))) { 443 /* do nothing */ 444 #ifndef PTY_ZEROREAD 445 } else if (len <= 0) { 446 #else 447 } else if ((!isatty(fdout) && len <= 0) || 448 (isatty(fdout) && (len < 0 || (len == 0 && errno != 0)))) { 449 #endif 450 fdout_eof = 1; 451 } else { 452 buffer_append(&stdout_buffer, buf, len); 453 fdout_bytes += len; 454 debug ("FD out now: %ld", fdout_bytes); 455 } 456 } 457 /* Read and buffer any available stderr data from the program. */ 458 if (!fderr_eof && FD_ISSET(fderr, readset)) { 459 errno = 0; 460 len = read(fderr, buf, sizeof(buf)); 461 if (len < 0 && (errno == EINTR || ((errno == EAGAIN || 462 errno == EWOULDBLOCK) && !child_terminated))) { 463 /* do nothing */ 464 #ifndef PTY_ZEROREAD 465 } else if (len <= 0) { 466 #else 467 } else if ((!isatty(fderr) && len <= 0) || 468 (isatty(fderr) && (len < 0 || (len == 0 && errno != 0)))) { 469 #endif 470 fderr_eof = 1; 471 } else { 472 buffer_append(&stderr_buffer, buf, len); 473 } 474 } 475 } 476 477 /* 478 * Sends data from internal buffers to client program stdin. 479 */ 480 static void 481 process_output(fd_set *writeset) 482 { 483 struct termios tio; 484 u_char *data; 485 u_int dlen; 486 int len; 487 488 /* Write buffered data to program stdin. */ 489 if (!compat20 && fdin != -1 && FD_ISSET(fdin, writeset)) { 490 data = buffer_ptr(&stdin_buffer); 491 dlen = buffer_len(&stdin_buffer); 492 len = write(fdin, data, dlen); 493 if (len < 0 && 494 (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK)) { 495 /* do nothing */ 496 } else if (len <= 0) { 497 if (fdin != fdout) 498 close(fdin); 499 else 500 shutdown(fdin, SHUT_WR); /* We will no longer send. */ 501 fdin = -1; 502 } else { 503 /* Successful write. */ 504 if (fdin_is_tty && dlen >= 1 && data[0] != '\r' && 505 tcgetattr(fdin, &tio) == 0 && 506 !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) { 507 /* 508 * Simulate echo to reduce the impact of 509 * traffic analysis 510 */ 511 packet_send_ignore(len); 512 packet_send(); 513 } 514 /* Consume the data from the buffer. */ 515 buffer_consume(&stdin_buffer, len); 516 /* Update the count of bytes written to the program. */ 517 stdin_bytes += len; 518 } 519 } 520 /* Send any buffered packet data to the client. */ 521 if (FD_ISSET(connection_out, writeset)) 522 stdin_bytes += packet_write_poll(); 523 } 524 525 /* 526 * Wait until all buffered output has been sent to the client. 527 * This is used when the program terminates. 528 */ 529 static void 530 drain_output(void) 531 { 532 /* Send any buffered stdout data to the client. */ 533 if (buffer_len(&stdout_buffer) > 0) { 534 packet_start(SSH_SMSG_STDOUT_DATA); 535 packet_put_string(buffer_ptr(&stdout_buffer), 536 buffer_len(&stdout_buffer)); 537 packet_send(); 538 /* Update the count of sent bytes. */ 539 stdout_bytes += buffer_len(&stdout_buffer); 540 } 541 /* Send any buffered stderr data to the client. */ 542 if (buffer_len(&stderr_buffer) > 0) { 543 packet_start(SSH_SMSG_STDERR_DATA); 544 packet_put_string(buffer_ptr(&stderr_buffer), 545 buffer_len(&stderr_buffer)); 546 packet_send(); 547 /* Update the count of sent bytes. */ 548 stderr_bytes += buffer_len(&stderr_buffer); 549 } 550 /* Wait until all buffered data has been written to the client. */ 551 packet_write_wait(); 552 } 553 554 static void 555 process_buffered_input_packets(void) 556 { 557 dispatch_run(DISPATCH_NONBLOCK, NULL, compat20 ? xxx_kex : NULL); 558 } 559 560 /* 561 * Performs the interactive session. This handles data transmission between 562 * the client and the program. Note that the notion of stdin, stdout, and 563 * stderr in this function is sort of reversed: this function writes to 564 * stdin (of the child program), and reads from stdout and stderr (of the 565 * child program). 566 */ 567 void 568 server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg) 569 { 570 fd_set *readset = NULL, *writeset = NULL; 571 int max_fd = 0; 572 u_int nalloc = 0; 573 int wait_status; /* Status returned by wait(). */ 574 pid_t wait_pid; /* pid returned by wait(). */ 575 int waiting_termination = 0; /* Have displayed waiting close message. */ 576 u_int max_time_milliseconds; 577 u_int previous_stdout_buffer_bytes; 578 u_int stdout_buffer_bytes; 579 int type; 580 581 debug("Entering interactive session."); 582 583 /* Initialize the SIGCHLD kludge. */ 584 child_terminated = 0; 585 mysignal(SIGCHLD, sigchld_handler); 586 587 if (!use_privsep) { 588 signal(SIGTERM, sigterm_handler); 589 signal(SIGINT, sigterm_handler); 590 signal(SIGQUIT, sigterm_handler); 591 } 592 593 /* Initialize our global variables. */ 594 fdin = fdin_arg; 595 fdout = fdout_arg; 596 fderr = fderr_arg; 597 598 /* nonblocking IO */ 599 set_nonblock(fdin); 600 set_nonblock(fdout); 601 /* we don't have stderr for interactive terminal sessions, see below */ 602 if (fderr != -1) 603 set_nonblock(fderr); 604 605 if (!(datafellows & SSH_BUG_IGNOREMSG) && isatty(fdin)) 606 fdin_is_tty = 1; 607 608 connection_in = packet_get_connection_in(); 609 connection_out = packet_get_connection_out(); 610 611 notify_setup(); 612 613 previous_stdout_buffer_bytes = 0; 614 615 /* Set approximate I/O buffer size. */ 616 if (packet_is_interactive()) 617 buffer_high = 4096; 618 else 619 buffer_high = 64 * 1024; 620 621 #if 0 622 /* Initialize max_fd to the maximum of the known file descriptors. */ 623 max_fd = MAX(connection_in, connection_out); 624 max_fd = MAX(max_fd, fdin); 625 max_fd = MAX(max_fd, fdout); 626 if (fderr != -1) 627 max_fd = MAX(max_fd, fderr); 628 #endif 629 630 /* Initialize Initialize buffers. */ 631 buffer_init(&stdin_buffer); 632 buffer_init(&stdout_buffer); 633 buffer_init(&stderr_buffer); 634 635 /* 636 * If we have no separate fderr (which is the case when we have a pty 637 * - there we cannot make difference between data sent to stdout and 638 * stderr), indicate that we have seen an EOF from stderr. This way 639 * we don't need to check the descriptor everywhere. 640 */ 641 if (fderr == -1) 642 fderr_eof = 1; 643 644 server_init_dispatch(); 645 646 /* Main loop of the server for the interactive session mode. */ 647 for (;;) { 648 649 /* Process buffered packets from the client. */ 650 process_buffered_input_packets(); 651 652 /* 653 * If we have received eof, and there is no more pending 654 * input data, cause a real eof by closing fdin. 655 */ 656 if (stdin_eof && fdin != -1 && buffer_len(&stdin_buffer) == 0) { 657 if (fdin != fdout) 658 close(fdin); 659 else 660 shutdown(fdin, SHUT_WR); /* We will no longer send. */ 661 fdin = -1; 662 } 663 /* Make packets from buffered stderr data to send to the client. */ 664 make_packets_from_stderr_data(); 665 666 /* 667 * Make packets from buffered stdout data to send to the 668 * client. If there is very little to send, this arranges to 669 * not send them now, but to wait a short while to see if we 670 * are getting more data. This is necessary, as some systems 671 * wake up readers from a pty after each separate character. 672 */ 673 max_time_milliseconds = 0; 674 stdout_buffer_bytes = buffer_len(&stdout_buffer); 675 if (stdout_buffer_bytes != 0 && stdout_buffer_bytes < 256 && 676 stdout_buffer_bytes != previous_stdout_buffer_bytes) { 677 /* try again after a while */ 678 max_time_milliseconds = 10; 679 } else { 680 /* Send it now. */ 681 make_packets_from_stdout_data(); 682 } 683 previous_stdout_buffer_bytes = buffer_len(&stdout_buffer); 684 685 /* Send channel data to the client. */ 686 if (packet_not_very_much_data_to_write()) 687 channel_output_poll(); 688 689 /* 690 * Bail out of the loop if the program has closed its output 691 * descriptors, and we have no more data to send to the 692 * client, and there is no pending buffered data. 693 */ 694 if (fdout_eof && fderr_eof && !packet_have_data_to_write() && 695 buffer_len(&stdout_buffer) == 0 && buffer_len(&stderr_buffer) == 0) { 696 if (!channel_still_open()) 697 break; 698 if (!waiting_termination) { 699 const char *s = "Waiting for forwarded connections to terminate...\r\n"; 700 char *cp; 701 waiting_termination = 1; 702 buffer_append(&stderr_buffer, s, strlen(s)); 703 704 /* Display list of open channels. */ 705 cp = channel_open_message(); 706 buffer_append(&stderr_buffer, cp, strlen(cp)); 707 xfree(cp); 708 } 709 } 710 max_fd = MAX(connection_in, connection_out); 711 max_fd = MAX(max_fd, fdin); 712 max_fd = MAX(max_fd, fdout); 713 max_fd = MAX(max_fd, fderr); 714 max_fd = MAX(max_fd, notify_pipe[0]); 715 716 /* Sleep in select() until we can do something. */ 717 wait_until_can_do_something(&readset, &writeset, &max_fd, 718 &nalloc, max_time_milliseconds); 719 720 if (received_sigterm) { 721 logit("Exiting on signal %d", received_sigterm); 722 /* Clean up sessions, utmp, etc. */ 723 cleanup_exit(255); 724 } 725 726 /* Process any channel events. */ 727 channel_after_select(readset, writeset); 728 729 /* Process input from the client and from program stdout/stderr. */ 730 process_input(readset); 731 732 /* Process output to the client and to program stdin. */ 733 process_output(writeset); 734 } 735 if (readset) 736 xfree(readset); 737 if (writeset) 738 xfree(writeset); 739 740 /* Cleanup and termination code. */ 741 742 /* Wait until all output has been sent to the client. */ 743 drain_output(); 744 745 debug("End of interactive session; stdin %ld, stdout (read %ld, sent %ld), stderr %ld bytes.", 746 stdin_bytes, fdout_bytes, stdout_bytes, stderr_bytes); 747 748 /* Free and clear the buffers. */ 749 buffer_free(&stdin_buffer); 750 buffer_free(&stdout_buffer); 751 buffer_free(&stderr_buffer); 752 753 /* Close the file descriptors. */ 754 if (fdout != -1) 755 close(fdout); 756 fdout = -1; 757 fdout_eof = 1; 758 if (fderr != -1) 759 close(fderr); 760 fderr = -1; 761 fderr_eof = 1; 762 if (fdin != -1) 763 close(fdin); 764 fdin = -1; 765 766 channel_free_all(); 767 768 /* We no longer want our SIGCHLD handler to be called. */ 769 mysignal(SIGCHLD, SIG_DFL); 770 771 while ((wait_pid = waitpid(-1, &wait_status, 0)) < 0) 772 if (errno != EINTR) 773 packet_disconnect("wait: %.100s", strerror(errno)); 774 if (wait_pid != pid) 775 error("Strange, wait returned pid %ld, expected %ld", 776 (long)wait_pid, (long)pid); 777 778 /* Check if it exited normally. */ 779 if (WIFEXITED(wait_status)) { 780 /* Yes, normal exit. Get exit status and send it to the client. */ 781 debug("Command exited with status %d.", WEXITSTATUS(wait_status)); 782 packet_start(SSH_SMSG_EXITSTATUS); 783 packet_put_int(WEXITSTATUS(wait_status)); 784 packet_send(); 785 packet_write_wait(); 786 787 /* 788 * Wait for exit confirmation. Note that there might be 789 * other packets coming before it; however, the program has 790 * already died so we just ignore them. The client is 791 * supposed to respond with the confirmation when it receives 792 * the exit status. 793 */ 794 do { 795 type = packet_read(); 796 } 797 while (type != SSH_CMSG_EXIT_CONFIRMATION); 798 799 debug("Received exit confirmation."); 800 return; 801 } 802 /* Check if the program terminated due to a signal. */ 803 if (WIFSIGNALED(wait_status)) 804 packet_disconnect("Command terminated on signal %d.", 805 WTERMSIG(wait_status)); 806 807 /* Some weird exit cause. Just exit. */ 808 packet_disconnect("wait returned status %04x.", wait_status); 809 /* NOTREACHED */ 810 } 811 812 static void 813 collect_children(void) 814 { 815 pid_t pid; 816 sigset_t oset, nset; 817 int status; 818 819 /* block SIGCHLD while we check for dead children */ 820 sigemptyset(&nset); 821 sigaddset(&nset, SIGCHLD); 822 sigprocmask(SIG_BLOCK, &nset, &oset); 823 if (child_terminated) { 824 debug("Received SIGCHLD."); 825 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 826 (pid < 0 && errno == EINTR)) 827 if (pid > 0) 828 session_close_by_pid(pid, status); 829 child_terminated = 0; 830 } 831 sigprocmask(SIG_SETMASK, &oset, NULL); 832 } 833 834 void 835 server_loop2(Authctxt *authctxt) 836 { 837 fd_set *readset = NULL, *writeset = NULL; 838 int rekeying = 0, max_fd, nalloc = 0; 839 double start_time, total_time; 840 841 debug("Entering interactive session for SSH2."); 842 start_time = get_current_time(); 843 844 mysignal(SIGCHLD, sigchld_handler); 845 child_terminated = 0; 846 connection_in = packet_get_connection_in(); 847 connection_out = packet_get_connection_out(); 848 849 if (!use_privsep) { 850 signal(SIGTERM, sigterm_handler); 851 signal(SIGINT, sigterm_handler); 852 signal(SIGQUIT, sigterm_handler); 853 } 854 855 notify_setup(); 856 857 max_fd = MAX(connection_in, connection_out); 858 max_fd = MAX(max_fd, notify_pipe[0]); 859 860 server_init_dispatch(); 861 862 for (;;) { 863 process_buffered_input_packets(); 864 865 rekeying = (xxx_kex != NULL && !xxx_kex->done); 866 867 if (!rekeying && packet_not_very_much_data_to_write()) 868 channel_output_poll(); 869 wait_until_can_do_something(&readset, &writeset, &max_fd, 870 &nalloc, 0); 871 872 if (received_sigterm) { 873 logit("Exiting on signal %d", received_sigterm); 874 /* Clean up sessions, utmp, etc. */ 875 cleanup_exit(255); 876 } 877 878 collect_children(); 879 if (!rekeying) { 880 channel_after_select(readset, writeset); 881 if (packet_need_rekeying()) { 882 debug("need rekeying"); 883 xxx_kex->done = 0; 884 kex_send_kexinit(xxx_kex); 885 } 886 } 887 process_input(readset); 888 if (connection_closed) 889 break; 890 process_output(writeset); 891 } 892 collect_children(); 893 894 if (readset) 895 xfree(readset); 896 if (writeset) 897 xfree(writeset); 898 899 /* free all channels, no more reads and writes */ 900 channel_free_all(); 901 902 /* free remaining sessions, e.g. remove wtmp entries */ 903 session_destroy_all(NULL); 904 total_time = get_current_time() - start_time; 905 logit("SSH: Server;LType: Throughput;Remote: %s-%d;IN: %lu;OUT: %lu;Duration: %.1f;tPut_in: %.1f;tPut_out: %.1f", 906 get_remote_ipaddr(), get_remote_port(), 907 stdin_bytes, fdout_bytes, total_time, stdin_bytes / total_time, 908 fdout_bytes / total_time); 909 } 910 911 static void 912 server_input_keep_alive(int type, u_int32_t seq, void *ctxt) 913 { 914 debug("Got %d/%u for keepalive", type, seq); 915 /* 916 * reset timeout, since we got a sane answer from the client. 917 * even if this was generated by something other than 918 * the bogus CHANNEL_REQUEST we send for keepalives. 919 */ 920 packet_set_alive_timeouts(0); 921 } 922 923 static void 924 server_input_stdin_data(int type, u_int32_t seq, void *ctxt) 925 { 926 char *data; 927 u_int data_len; 928 929 /* Stdin data from the client. Append it to the buffer. */ 930 /* Ignore any data if the client has closed stdin. */ 931 if (fdin == -1) 932 return; 933 data = packet_get_string(&data_len); 934 packet_check_eom(); 935 buffer_append(&stdin_buffer, data, data_len); 936 memset(data, 0, data_len); 937 xfree(data); 938 } 939 940 static void 941 server_input_eof(int type, u_int32_t seq, void *ctxt) 942 { 943 /* 944 * Eof from the client. The stdin descriptor to the 945 * program will be closed when all buffered data has 946 * drained. 947 */ 948 debug("EOF received for stdin."); 949 packet_check_eom(); 950 stdin_eof = 1; 951 } 952 953 static void 954 server_input_window_size(int type, u_int32_t seq, void *ctxt) 955 { 956 u_int row = packet_get_int(); 957 u_int col = packet_get_int(); 958 u_int xpixel = packet_get_int(); 959 u_int ypixel = packet_get_int(); 960 961 debug("Window change received."); 962 packet_check_eom(); 963 if (fdin != -1) 964 pty_change_window_size(fdin, row, col, xpixel, ypixel); 965 } 966 967 static Channel * 968 server_request_direct_tcpip(void) 969 { 970 Channel *c; 971 char *target, *originator; 972 u_short target_port, originator_port; 973 974 target = packet_get_string(NULL); 975 target_port = packet_get_int(); 976 originator = packet_get_string(NULL); 977 originator_port = packet_get_int(); 978 packet_check_eom(); 979 980 debug("server_request_direct_tcpip: originator %s port %d, target %s " 981 "port %d", originator, originator_port, target, target_port); 982 983 /* XXX check permission */ 984 c = channel_connect_to(target, target_port, 985 "direct-tcpip", "direct-tcpip"); 986 987 xfree(originator); 988 xfree(target); 989 990 return c; 991 } 992 993 static Channel * 994 server_request_tun(void) 995 { 996 Channel *c = NULL; 997 int mode, tun; 998 int sock; 999 1000 mode = packet_get_int(); 1001 switch (mode) { 1002 case SSH_TUNMODE_POINTOPOINT: 1003 case SSH_TUNMODE_ETHERNET: 1004 break; 1005 default: 1006 packet_send_debug("Unsupported tunnel device mode."); 1007 return NULL; 1008 } 1009 if ((options.permit_tun & mode) == 0) { 1010 packet_send_debug("Server has rejected tunnel device " 1011 "forwarding"); 1012 return NULL; 1013 } 1014 1015 tun = packet_get_int(); 1016 if (forced_tun_device != -1) { 1017 if (tun != SSH_TUNID_ANY && forced_tun_device != tun) 1018 goto done; 1019 tun = forced_tun_device; 1020 } 1021 sock = tun_open(tun, mode); 1022 if (sock < 0) 1023 goto done; 1024 if (options.hpn_disabled) 1025 c = channel_new("tun", SSH_CHANNEL_OPEN, sock, sock, -1, 1026 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1); 1027 else 1028 c = channel_new("tun", SSH_CHANNEL_OPEN, sock, sock, -1, 1029 options.hpn_buffer_size, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1); 1030 c->datagram = 1; 1031 #if defined(SSH_TUN_FILTER) 1032 if (mode == SSH_TUNMODE_POINTOPOINT) 1033 channel_register_filter(c->self, sys_tun_infilter, 1034 sys_tun_outfilter, NULL, NULL); 1035 #endif 1036 1037 done: 1038 if (c == NULL) 1039 packet_send_debug("Failed to open the tunnel device."); 1040 return c; 1041 } 1042 1043 static Channel * 1044 server_request_session(void) 1045 { 1046 Channel *c; 1047 1048 debug("input_session_request"); 1049 packet_check_eom(); 1050 1051 if (no_more_sessions) { 1052 packet_disconnect("Possible attack: attempt to open a session " 1053 "after additional sessions disabled"); 1054 } 1055 1056 /* 1057 * A server session has no fd to read or write until a 1058 * CHANNEL_REQUEST for a shell is made, so we set the type to 1059 * SSH_CHANNEL_LARVAL. Additionally, a callback for handling all 1060 * CHANNEL_REQUEST messages is registered. 1061 */ 1062 c = channel_new("session", SSH_CHANNEL_LARVAL, 1063 -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT, 1064 0, "server-session", 1); 1065 if ((options.tcp_rcv_buf_poll) && (!options.hpn_disabled)) 1066 c->dynamic_window = 1; 1067 if (session_open(the_authctxt, c->self) != 1) { 1068 debug("session open failed, free channel %d", c->self); 1069 channel_free(c); 1070 return NULL; 1071 } 1072 channel_register_cleanup(c->self, session_close_by_channel, 0); 1073 return c; 1074 } 1075 1076 static void 1077 server_input_channel_open(int type, u_int32_t seq, void *ctxt) 1078 { 1079 Channel *c = NULL; 1080 char *ctype; 1081 int rchan; 1082 u_int rmaxpack, rwindow, len; 1083 1084 ctype = packet_get_string(&len); 1085 rchan = packet_get_int(); 1086 rwindow = packet_get_int(); 1087 rmaxpack = packet_get_int(); 1088 1089 debug("server_input_channel_open: ctype %s rchan %d win %d max %d", 1090 ctype, rchan, rwindow, rmaxpack); 1091 1092 if (strcmp(ctype, "session") == 0) { 1093 c = server_request_session(); 1094 } else if (strcmp(ctype, "direct-tcpip") == 0) { 1095 c = server_request_direct_tcpip(); 1096 } else if (strcmp(ctype, "tun@openssh.com") == 0) { 1097 c = server_request_tun(); 1098 } 1099 if (c != NULL) { 1100 debug("server_input_channel_open: confirm %s", ctype); 1101 c->remote_id = rchan; 1102 c->remote_window = rwindow; 1103 c->remote_maxpacket = rmaxpack; 1104 if (c->type != SSH_CHANNEL_CONNECTING) { 1105 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION); 1106 packet_put_int(c->remote_id); 1107 packet_put_int(c->self); 1108 packet_put_int(c->local_window); 1109 packet_put_int(c->local_maxpacket); 1110 packet_send(); 1111 } 1112 } else { 1113 debug("server_input_channel_open: failure %s", ctype); 1114 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE); 1115 packet_put_int(rchan); 1116 packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED); 1117 if (!(datafellows & SSH_BUG_OPENFAILURE)) { 1118 packet_put_cstring("open failed"); 1119 packet_put_cstring(""); 1120 } 1121 packet_send(); 1122 } 1123 xfree(ctype); 1124 } 1125 1126 static void 1127 server_input_global_request(int type, u_int32_t seq, void *ctxt) 1128 { 1129 char *rtype; 1130 int want_reply; 1131 int success = 0, allocated_listen_port = 0; 1132 1133 rtype = packet_get_string(NULL); 1134 want_reply = packet_get_char(); 1135 debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply); 1136 1137 /* -R style forwarding */ 1138 if (strcmp(rtype, "tcpip-forward") == 0) { 1139 struct passwd *pw; 1140 char *listen_address; 1141 u_short listen_port; 1142 1143 pw = the_authctxt->pw; 1144 if (pw == NULL || !the_authctxt->valid) 1145 fatal("server_input_global_request: no/invalid user"); 1146 listen_address = packet_get_string(NULL); 1147 listen_port = (u_short)packet_get_int(); 1148 debug("server_input_global_request: tcpip-forward listen %s port %d", 1149 listen_address, listen_port); 1150 1151 /* check permissions */ 1152 if (!options.allow_tcp_forwarding || 1153 no_port_forwarding_flag || 1154 (!want_reply && listen_port == 0) 1155 #ifndef NO_IPPORT_RESERVED_CONCEPT 1156 || (listen_port != 0 && listen_port < IPPORT_RESERVED && 1157 pw->pw_uid != 0) 1158 #endif 1159 ) { 1160 success = 0; 1161 packet_send_debug("Server has disabled port forwarding."); 1162 } else { 1163 /* Start listening on the port */ 1164 success = channel_setup_remote_fwd_listener( 1165 listen_address, listen_port, 1166 &allocated_listen_port, options.gateway_ports); 1167 } 1168 xfree(listen_address); 1169 } else if (strcmp(rtype, "cancel-tcpip-forward") == 0) { 1170 char *cancel_address; 1171 u_short cancel_port; 1172 1173 cancel_address = packet_get_string(NULL); 1174 cancel_port = (u_short)packet_get_int(); 1175 debug("%s: cancel-tcpip-forward addr %s port %d", __func__, 1176 cancel_address, cancel_port); 1177 1178 success = channel_cancel_rport_listener(cancel_address, 1179 cancel_port); 1180 xfree(cancel_address); 1181 } else if (strcmp(rtype, "no-more-sessions@openssh.com") == 0) { 1182 no_more_sessions = 1; 1183 success = 1; 1184 } 1185 if (want_reply) { 1186 packet_start(success ? 1187 SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE); 1188 if (success && allocated_listen_port > 0) 1189 packet_put_int(allocated_listen_port); 1190 packet_send(); 1191 packet_write_wait(); 1192 } 1193 xfree(rtype); 1194 } 1195 1196 static void 1197 server_input_channel_req(int type, u_int32_t seq, void *ctxt) 1198 { 1199 Channel *c; 1200 int id, reply, success = 0; 1201 char *rtype; 1202 1203 id = packet_get_int(); 1204 rtype = packet_get_string(NULL); 1205 reply = packet_get_char(); 1206 1207 debug("server_input_channel_req: channel %d request %s reply %d", 1208 id, rtype, reply); 1209 1210 if ((c = channel_lookup(id)) == NULL) 1211 packet_disconnect("server_input_channel_req: " 1212 "unknown channel %d", id); 1213 if (!strcmp(rtype, "eow@openssh.com")) { 1214 packet_check_eom(); 1215 chan_rcvd_eow(c); 1216 } else if ((c->type == SSH_CHANNEL_LARVAL || 1217 c->type == SSH_CHANNEL_OPEN) && strcmp(c->ctype, "session") == 0) 1218 success = session_input_channel_req(c, rtype); 1219 if (reply) { 1220 packet_start(success ? 1221 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE); 1222 packet_put_int(c->remote_id); 1223 packet_send(); 1224 } 1225 xfree(rtype); 1226 } 1227 1228 static void 1229 server_init_dispatch_20(void) 1230 { 1231 debug("server_init_dispatch_20"); 1232 dispatch_init(&dispatch_protocol_error); 1233 dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); 1234 dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data); 1235 dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); 1236 dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); 1237 dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open); 1238 dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 1239 dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 1240 dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req); 1241 dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); 1242 dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request); 1243 /* client_alive */ 1244 dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &server_input_keep_alive); 1245 dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_keep_alive); 1246 dispatch_set(SSH2_MSG_REQUEST_SUCCESS, &server_input_keep_alive); 1247 dispatch_set(SSH2_MSG_REQUEST_FAILURE, &server_input_keep_alive); 1248 /* rekeying */ 1249 dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); 1250 } 1251 static void 1252 server_init_dispatch_13(void) 1253 { 1254 debug("server_init_dispatch_13"); 1255 dispatch_init(NULL); 1256 dispatch_set(SSH_CMSG_EOF, &server_input_eof); 1257 dispatch_set(SSH_CMSG_STDIN_DATA, &server_input_stdin_data); 1258 dispatch_set(SSH_CMSG_WINDOW_SIZE, &server_input_window_size); 1259 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close); 1260 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation); 1261 dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data); 1262 dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 1263 dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 1264 dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open); 1265 } 1266 static void 1267 server_init_dispatch_15(void) 1268 { 1269 server_init_dispatch_13(); 1270 debug("server_init_dispatch_15"); 1271 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof); 1272 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_oclose); 1273 } 1274 static void 1275 server_init_dispatch(void) 1276 { 1277 if (compat20) 1278 server_init_dispatch_20(); 1279 else if (compat13) 1280 server_init_dispatch_13(); 1281 else 1282 server_init_dispatch_15(); 1283 } 1284