1 /* $OpenBSD: serverloop.c,v 1.162 2012/06/20 04:42:58 djm 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, FD_CLOEXEC) == -1) || 149 (fcntl(notify_pipe[1], F_SETFD, FD_CLOEXEC) == -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 time_t minwait_secs = 0; 299 int client_alive_scheduled = 0; 300 int program_alive_scheduled = 0; 301 302 /* Allocate and update select() masks for channel descriptors. */ 303 channel_prepare_select(readsetp, writesetp, maxfdp, nallocp, 304 &minwait_secs, 0); 305 306 if (minwait_secs != 0) 307 max_time_milliseconds = MIN(max_time_milliseconds, 308 (u_int)minwait_secs * 1000); 309 310 /* 311 * if using client_alive, set the max timeout accordingly, 312 * and indicate that this particular timeout was for client 313 * alive by setting the client_alive_scheduled flag. 314 * 315 * this could be randomized somewhat to make traffic 316 * analysis more difficult, but we're not doing it yet. 317 */ 318 if (compat20 && 319 max_time_milliseconds == 0 && options.client_alive_interval) { 320 client_alive_scheduled = 1; 321 max_time_milliseconds = options.client_alive_interval * 1000; 322 } 323 324 if (compat20) { 325 #if 0 326 /* wrong: bad condition XXX */ 327 if (channel_not_very_much_buffered_data()) 328 #endif 329 FD_SET(connection_in, *readsetp); 330 } else { 331 /* 332 * Read packets from the client unless we have too much 333 * buffered stdin or channel data. 334 */ 335 if (buffer_len(&stdin_buffer) < buffer_high && 336 channel_not_very_much_buffered_data()) 337 FD_SET(connection_in, *readsetp); 338 /* 339 * If there is not too much data already buffered going to 340 * the client, try to get some more data from the program. 341 */ 342 if (packet_not_very_much_data_to_write()) { 343 program_alive_scheduled = child_terminated; 344 if (!fdout_eof) 345 FD_SET(fdout, *readsetp); 346 if (!fderr_eof) 347 FD_SET(fderr, *readsetp); 348 } 349 /* 350 * If we have buffered data, try to write some of that data 351 * to the program. 352 */ 353 if (fdin != -1 && buffer_len(&stdin_buffer) > 0) 354 FD_SET(fdin, *writesetp); 355 } 356 notify_prepare(*readsetp); 357 358 /* 359 * If we have buffered packet data going to the client, mark that 360 * descriptor. 361 */ 362 if (packet_have_data_to_write()) 363 FD_SET(connection_out, *writesetp); 364 365 /* 366 * If child has terminated and there is enough buffer space to read 367 * from it, then read as much as is available and exit. 368 */ 369 if (child_terminated && packet_not_very_much_data_to_write()) 370 if (max_time_milliseconds == 0 || client_alive_scheduled) 371 max_time_milliseconds = 100; 372 373 if (max_time_milliseconds == 0) 374 tvp = NULL; 375 else { 376 tv.tv_sec = max_time_milliseconds / 1000; 377 tv.tv_usec = 1000 * (max_time_milliseconds % 1000); 378 tvp = &tv; 379 } 380 381 /* Wait for something to happen, or the timeout to expire. */ 382 ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp); 383 384 if (ret == -1) { 385 memset(*readsetp, 0, *nallocp); 386 memset(*writesetp, 0, *nallocp); 387 if (errno != EINTR) 388 error("select: %.100s", strerror(errno)); 389 } else { 390 if (ret == 0 && client_alive_scheduled) 391 client_alive_check(); 392 if (!compat20 && program_alive_scheduled && fdin_is_tty) { 393 if (!fdout_eof) 394 FD_SET(fdout, *readsetp); 395 if (!fderr_eof) 396 FD_SET(fderr, *readsetp); 397 } 398 } 399 400 notify_done(*readsetp); 401 } 402 403 /* 404 * Processes input from the client and the program. Input data is stored 405 * in buffers and processed later. 406 */ 407 static void 408 process_input(fd_set *readset) 409 { 410 int len; 411 char buf[16384]; 412 413 /* Read and buffer any input data from the client. */ 414 if (FD_ISSET(connection_in, readset)) { 415 int cont = 0; 416 len = roaming_read(connection_in, buf, sizeof(buf), &cont); 417 if (len == 0) { 418 if (cont) 419 return; 420 verbose("Connection closed by %.100s", 421 get_remote_ipaddr()); 422 connection_closed = 1; 423 if (compat20) 424 return; 425 cleanup_exit(255); 426 } else if (len < 0) { 427 if (errno != EINTR && errno != EAGAIN && 428 errno != EWOULDBLOCK) { 429 verbose("Read error from remote host " 430 "%.100s: %.100s", 431 get_remote_ipaddr(), strerror(errno)); 432 cleanup_exit(255); 433 } 434 } else { 435 /* Buffer any received data. */ 436 packet_process_incoming(buf, len); 437 fdout_bytes += len; 438 } 439 } 440 if (compat20) 441 return; 442 443 /* Read and buffer any available stdout data from the program. */ 444 if (!fdout_eof && FD_ISSET(fdout, readset)) { 445 errno = 0; 446 len = read(fdout, buf, sizeof(buf)); 447 if (len < 0 && (errno == EINTR || ((errno == EAGAIN || 448 errno == EWOULDBLOCK) && !child_terminated))) { 449 /* do nothing */ 450 #ifndef PTY_ZEROREAD 451 } else if (len <= 0) { 452 #else 453 } else if ((!isatty(fdout) && len <= 0) || 454 (isatty(fdout) && (len < 0 || (len == 0 && errno != 0)))) { 455 #endif 456 fdout_eof = 1; 457 } else { 458 buffer_append(&stdout_buffer, buf, len); 459 fdout_bytes += len; 460 debug ("FD out now: %ld", fdout_bytes); 461 } 462 } 463 /* Read and buffer any available stderr data from the program. */ 464 if (!fderr_eof && FD_ISSET(fderr, readset)) { 465 errno = 0; 466 len = read(fderr, buf, sizeof(buf)); 467 if (len < 0 && (errno == EINTR || ((errno == EAGAIN || 468 errno == EWOULDBLOCK) && !child_terminated))) { 469 /* do nothing */ 470 #ifndef PTY_ZEROREAD 471 } else if (len <= 0) { 472 #else 473 } else if ((!isatty(fderr) && len <= 0) || 474 (isatty(fderr) && (len < 0 || (len == 0 && errno != 0)))) { 475 #endif 476 fderr_eof = 1; 477 } else { 478 buffer_append(&stderr_buffer, buf, len); 479 } 480 } 481 } 482 483 /* 484 * Sends data from internal buffers to client program stdin. 485 */ 486 static void 487 process_output(fd_set *writeset) 488 { 489 struct termios tio; 490 u_char *data; 491 u_int dlen; 492 int len; 493 494 /* Write buffered data to program stdin. */ 495 if (!compat20 && fdin != -1 && FD_ISSET(fdin, writeset)) { 496 data = buffer_ptr(&stdin_buffer); 497 dlen = buffer_len(&stdin_buffer); 498 len = write(fdin, data, dlen); 499 if (len < 0 && 500 (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK)) { 501 /* do nothing */ 502 } else if (len <= 0) { 503 if (fdin != fdout) 504 close(fdin); 505 else 506 shutdown(fdin, SHUT_WR); /* We will no longer send. */ 507 fdin = -1; 508 } else { 509 /* Successful write. */ 510 if (fdin_is_tty && dlen >= 1 && data[0] != '\r' && 511 tcgetattr(fdin, &tio) == 0 && 512 !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) { 513 /* 514 * Simulate echo to reduce the impact of 515 * traffic analysis 516 */ 517 packet_send_ignore(len); 518 packet_send(); 519 } 520 /* Consume the data from the buffer. */ 521 buffer_consume(&stdin_buffer, len); 522 /* Update the count of bytes written to the program. */ 523 stdin_bytes += len; 524 } 525 } 526 /* Send any buffered packet data to the client. */ 527 if (FD_ISSET(connection_out, writeset)) 528 stdin_bytes += packet_write_poll(); 529 } 530 531 /* 532 * Wait until all buffered output has been sent to the client. 533 * This is used when the program terminates. 534 */ 535 static void 536 drain_output(void) 537 { 538 /* Send any buffered stdout data to the client. */ 539 if (buffer_len(&stdout_buffer) > 0) { 540 packet_start(SSH_SMSG_STDOUT_DATA); 541 packet_put_string(buffer_ptr(&stdout_buffer), 542 buffer_len(&stdout_buffer)); 543 packet_send(); 544 /* Update the count of sent bytes. */ 545 stdout_bytes += buffer_len(&stdout_buffer); 546 } 547 /* Send any buffered stderr data to the client. */ 548 if (buffer_len(&stderr_buffer) > 0) { 549 packet_start(SSH_SMSG_STDERR_DATA); 550 packet_put_string(buffer_ptr(&stderr_buffer), 551 buffer_len(&stderr_buffer)); 552 packet_send(); 553 /* Update the count of sent bytes. */ 554 stderr_bytes += buffer_len(&stderr_buffer); 555 } 556 /* Wait until all buffered data has been written to the client. */ 557 packet_write_wait(); 558 } 559 560 static void 561 process_buffered_input_packets(void) 562 { 563 dispatch_run(DISPATCH_NONBLOCK, NULL, compat20 ? xxx_kex : NULL); 564 } 565 566 /* 567 * Performs the interactive session. This handles data transmission between 568 * the client and the program. Note that the notion of stdin, stdout, and 569 * stderr in this function is sort of reversed: this function writes to 570 * stdin (of the child program), and reads from stdout and stderr (of the 571 * child program). 572 */ 573 void 574 server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg) 575 { 576 fd_set *readset = NULL, *writeset = NULL; 577 int max_fd = 0; 578 u_int nalloc = 0; 579 int wait_status; /* Status returned by wait(). */ 580 pid_t wait_pid; /* pid returned by wait(). */ 581 int waiting_termination = 0; /* Have displayed waiting close message. */ 582 u_int max_time_milliseconds; 583 u_int previous_stdout_buffer_bytes; 584 u_int stdout_buffer_bytes; 585 int type; 586 587 debug("Entering interactive session."); 588 589 /* Initialize the SIGCHLD kludge. */ 590 child_terminated = 0; 591 mysignal(SIGCHLD, sigchld_handler); 592 593 if (!use_privsep) { 594 signal(SIGTERM, sigterm_handler); 595 signal(SIGINT, sigterm_handler); 596 signal(SIGQUIT, sigterm_handler); 597 } 598 599 /* Initialize our global variables. */ 600 fdin = fdin_arg; 601 fdout = fdout_arg; 602 fderr = fderr_arg; 603 604 /* nonblocking IO */ 605 set_nonblock(fdin); 606 set_nonblock(fdout); 607 /* we don't have stderr for interactive terminal sessions, see below */ 608 if (fderr != -1) 609 set_nonblock(fderr); 610 611 if (!(datafellows & SSH_BUG_IGNOREMSG) && isatty(fdin)) 612 fdin_is_tty = 1; 613 614 connection_in = packet_get_connection_in(); 615 connection_out = packet_get_connection_out(); 616 617 notify_setup(); 618 619 previous_stdout_buffer_bytes = 0; 620 621 /* Set approximate I/O buffer size. */ 622 if (packet_is_interactive()) 623 buffer_high = 4096; 624 else 625 buffer_high = 64 * 1024; 626 627 #if 0 628 /* Initialize max_fd to the maximum of the known file descriptors. */ 629 max_fd = MAX(connection_in, connection_out); 630 max_fd = MAX(max_fd, fdin); 631 max_fd = MAX(max_fd, fdout); 632 if (fderr != -1) 633 max_fd = MAX(max_fd, fderr); 634 #endif 635 636 /* Initialize Initialize buffers. */ 637 buffer_init(&stdin_buffer); 638 buffer_init(&stdout_buffer); 639 buffer_init(&stderr_buffer); 640 641 /* 642 * If we have no separate fderr (which is the case when we have a pty 643 * - there we cannot make difference between data sent to stdout and 644 * stderr), indicate that we have seen an EOF from stderr. This way 645 * we don't need to check the descriptor everywhere. 646 */ 647 if (fderr == -1) 648 fderr_eof = 1; 649 650 server_init_dispatch(); 651 652 /* Main loop of the server for the interactive session mode. */ 653 for (;;) { 654 655 /* Process buffered packets from the client. */ 656 process_buffered_input_packets(); 657 658 /* 659 * If we have received eof, and there is no more pending 660 * input data, cause a real eof by closing fdin. 661 */ 662 if (stdin_eof && fdin != -1 && buffer_len(&stdin_buffer) == 0) { 663 if (fdin != fdout) 664 close(fdin); 665 else 666 shutdown(fdin, SHUT_WR); /* We will no longer send. */ 667 fdin = -1; 668 } 669 /* Make packets from buffered stderr data to send to the client. */ 670 make_packets_from_stderr_data(); 671 672 /* 673 * Make packets from buffered stdout data to send to the 674 * client. If there is very little to send, this arranges to 675 * not send them now, but to wait a short while to see if we 676 * are getting more data. This is necessary, as some systems 677 * wake up readers from a pty after each separate character. 678 */ 679 max_time_milliseconds = 0; 680 stdout_buffer_bytes = buffer_len(&stdout_buffer); 681 if (stdout_buffer_bytes != 0 && stdout_buffer_bytes < 256 && 682 stdout_buffer_bytes != previous_stdout_buffer_bytes) { 683 /* try again after a while */ 684 max_time_milliseconds = 10; 685 } else { 686 /* Send it now. */ 687 make_packets_from_stdout_data(); 688 } 689 previous_stdout_buffer_bytes = buffer_len(&stdout_buffer); 690 691 /* Send channel data to the client. */ 692 if (packet_not_very_much_data_to_write()) 693 channel_output_poll(); 694 695 /* 696 * Bail out of the loop if the program has closed its output 697 * descriptors, and we have no more data to send to the 698 * client, and there is no pending buffered data. 699 */ 700 if (fdout_eof && fderr_eof && !packet_have_data_to_write() && 701 buffer_len(&stdout_buffer) == 0 && buffer_len(&stderr_buffer) == 0) { 702 if (!channel_still_open()) 703 break; 704 if (!waiting_termination) { 705 const char *s = "Waiting for forwarded connections to terminate...\r\n"; 706 char *cp; 707 waiting_termination = 1; 708 buffer_append(&stderr_buffer, s, strlen(s)); 709 710 /* Display list of open channels. */ 711 cp = channel_open_message(); 712 buffer_append(&stderr_buffer, cp, strlen(cp)); 713 xfree(cp); 714 } 715 } 716 max_fd = MAX(connection_in, connection_out); 717 max_fd = MAX(max_fd, fdin); 718 max_fd = MAX(max_fd, fdout); 719 max_fd = MAX(max_fd, fderr); 720 max_fd = MAX(max_fd, notify_pipe[0]); 721 722 /* Sleep in select() until we can do something. */ 723 wait_until_can_do_something(&readset, &writeset, &max_fd, 724 &nalloc, max_time_milliseconds); 725 726 if (received_sigterm) { 727 logit("Exiting on signal %d", received_sigterm); 728 /* Clean up sessions, utmp, etc. */ 729 cleanup_exit(255); 730 } 731 732 /* Process any channel events. */ 733 channel_after_select(readset, writeset); 734 735 /* Process input from the client and from program stdout/stderr. */ 736 process_input(readset); 737 738 /* Process output to the client and to program stdin. */ 739 process_output(writeset); 740 } 741 if (readset) 742 xfree(readset); 743 if (writeset) 744 xfree(writeset); 745 746 /* Cleanup and termination code. */ 747 748 /* Wait until all output has been sent to the client. */ 749 drain_output(); 750 751 debug("End of interactive session; stdin %ld, stdout (read %ld, sent %ld), stderr %ld bytes.", 752 stdin_bytes, fdout_bytes, stdout_bytes, stderr_bytes); 753 754 /* Free and clear the buffers. */ 755 buffer_free(&stdin_buffer); 756 buffer_free(&stdout_buffer); 757 buffer_free(&stderr_buffer); 758 759 /* Close the file descriptors. */ 760 if (fdout != -1) 761 close(fdout); 762 fdout = -1; 763 fdout_eof = 1; 764 if (fderr != -1) 765 close(fderr); 766 fderr = -1; 767 fderr_eof = 1; 768 if (fdin != -1) 769 close(fdin); 770 fdin = -1; 771 772 channel_free_all(); 773 774 /* We no longer want our SIGCHLD handler to be called. */ 775 mysignal(SIGCHLD, SIG_DFL); 776 777 while ((wait_pid = waitpid(-1, &wait_status, 0)) < 0) 778 if (errno != EINTR) 779 packet_disconnect("wait: %.100s", strerror(errno)); 780 if (wait_pid != pid) 781 error("Strange, wait returned pid %ld, expected %ld", 782 (long)wait_pid, (long)pid); 783 784 /* Check if it exited normally. */ 785 if (WIFEXITED(wait_status)) { 786 /* Yes, normal exit. Get exit status and send it to the client. */ 787 debug("Command exited with status %d.", WEXITSTATUS(wait_status)); 788 packet_start(SSH_SMSG_EXITSTATUS); 789 packet_put_int(WEXITSTATUS(wait_status)); 790 packet_send(); 791 packet_write_wait(); 792 793 /* 794 * Wait for exit confirmation. Note that there might be 795 * other packets coming before it; however, the program has 796 * already died so we just ignore them. The client is 797 * supposed to respond with the confirmation when it receives 798 * the exit status. 799 */ 800 do { 801 type = packet_read(); 802 } 803 while (type != SSH_CMSG_EXIT_CONFIRMATION); 804 805 debug("Received exit confirmation."); 806 return; 807 } 808 /* Check if the program terminated due to a signal. */ 809 if (WIFSIGNALED(wait_status)) 810 packet_disconnect("Command terminated on signal %d.", 811 WTERMSIG(wait_status)); 812 813 /* Some weird exit cause. Just exit. */ 814 packet_disconnect("wait returned status %04x.", wait_status); 815 /* NOTREACHED */ 816 } 817 818 static void 819 collect_children(void) 820 { 821 pid_t pid; 822 sigset_t oset, nset; 823 int status; 824 825 /* block SIGCHLD while we check for dead children */ 826 sigemptyset(&nset); 827 sigaddset(&nset, SIGCHLD); 828 sigprocmask(SIG_BLOCK, &nset, &oset); 829 if (child_terminated) { 830 debug("Received SIGCHLD."); 831 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 832 (pid < 0 && errno == EINTR)) 833 if (pid > 0) 834 session_close_by_pid(pid, status); 835 child_terminated = 0; 836 } 837 sigprocmask(SIG_SETMASK, &oset, NULL); 838 } 839 840 void 841 server_loop2(Authctxt *authctxt) 842 { 843 fd_set *readset = NULL, *writeset = NULL; 844 int rekeying = 0, max_fd, nalloc = 0; 845 double start_time, total_time; 846 847 debug("Entering interactive session for SSH2."); 848 start_time = get_current_time(); 849 850 mysignal(SIGCHLD, sigchld_handler); 851 child_terminated = 0; 852 connection_in = packet_get_connection_in(); 853 connection_out = packet_get_connection_out(); 854 855 if (!use_privsep) { 856 signal(SIGTERM, sigterm_handler); 857 signal(SIGINT, sigterm_handler); 858 signal(SIGQUIT, sigterm_handler); 859 } 860 861 notify_setup(); 862 863 max_fd = MAX(connection_in, connection_out); 864 max_fd = MAX(max_fd, notify_pipe[0]); 865 866 server_init_dispatch(); 867 868 for (;;) { 869 process_buffered_input_packets(); 870 871 rekeying = (xxx_kex != NULL && !xxx_kex->done); 872 873 if (!rekeying && packet_not_very_much_data_to_write()) 874 channel_output_poll(); 875 wait_until_can_do_something(&readset, &writeset, &max_fd, 876 &nalloc, 0); 877 878 if (received_sigterm) { 879 logit("Exiting on signal %d", received_sigterm); 880 /* Clean up sessions, utmp, etc. */ 881 cleanup_exit(255); 882 } 883 884 collect_children(); 885 if (!rekeying) { 886 channel_after_select(readset, writeset); 887 if (packet_need_rekeying()) { 888 debug("need rekeying"); 889 xxx_kex->done = 0; 890 kex_send_kexinit(xxx_kex); 891 } 892 } 893 process_input(readset); 894 if (connection_closed) 895 break; 896 process_output(writeset); 897 } 898 collect_children(); 899 900 if (readset) 901 xfree(readset); 902 if (writeset) 903 xfree(writeset); 904 905 /* free all channels, no more reads and writes */ 906 channel_free_all(); 907 908 /* free remaining sessions, e.g. remove wtmp entries */ 909 session_destroy_all(NULL); 910 total_time = get_current_time() - start_time; 911 logit("SSH: Server;LType: Throughput;Remote: %s-%d;IN: %lu;OUT: %lu;Duration: %.1f;tPut_in: %.1f;tPut_out: %.1f", 912 get_remote_ipaddr(), get_remote_port(), 913 stdin_bytes, fdout_bytes, total_time, stdin_bytes / total_time, 914 fdout_bytes / total_time); 915 } 916 917 static void 918 server_input_keep_alive(int type, u_int32_t seq, void *ctxt) 919 { 920 debug("Got %d/%u for keepalive", type, seq); 921 /* 922 * reset timeout, since we got a sane answer from the client. 923 * even if this was generated by something other than 924 * the bogus CHANNEL_REQUEST we send for keepalives. 925 */ 926 packet_set_alive_timeouts(0); 927 } 928 929 static void 930 server_input_stdin_data(int type, u_int32_t seq, void *ctxt) 931 { 932 char *data; 933 u_int data_len; 934 935 /* Stdin data from the client. Append it to the buffer. */ 936 /* Ignore any data if the client has closed stdin. */ 937 if (fdin == -1) 938 return; 939 data = packet_get_string(&data_len); 940 packet_check_eom(); 941 buffer_append(&stdin_buffer, data, data_len); 942 memset(data, 0, data_len); 943 xfree(data); 944 } 945 946 static void 947 server_input_eof(int type, u_int32_t seq, void *ctxt) 948 { 949 /* 950 * Eof from the client. The stdin descriptor to the 951 * program will be closed when all buffered data has 952 * drained. 953 */ 954 debug("EOF received for stdin."); 955 packet_check_eom(); 956 stdin_eof = 1; 957 } 958 959 static void 960 server_input_window_size(int type, u_int32_t seq, void *ctxt) 961 { 962 u_int row = packet_get_int(); 963 u_int col = packet_get_int(); 964 u_int xpixel = packet_get_int(); 965 u_int ypixel = packet_get_int(); 966 967 debug("Window change received."); 968 packet_check_eom(); 969 if (fdin != -1) 970 pty_change_window_size(fdin, row, col, xpixel, ypixel); 971 } 972 973 static Channel * 974 server_request_direct_tcpip(void) 975 { 976 Channel *c; 977 char *target, *originator; 978 u_short target_port, originator_port; 979 980 target = packet_get_string(NULL); 981 target_port = packet_get_int(); 982 originator = packet_get_string(NULL); 983 originator_port = packet_get_int(); 984 packet_check_eom(); 985 986 debug("server_request_direct_tcpip: originator %s port %d, target %s " 987 "port %d", originator, originator_port, target, target_port); 988 989 /* XXX check permission */ 990 c = channel_connect_to(target, target_port, 991 "direct-tcpip", "direct-tcpip"); 992 993 xfree(originator); 994 xfree(target); 995 996 return c; 997 } 998 999 static Channel * 1000 server_request_tun(void) 1001 { 1002 Channel *c = NULL; 1003 int mode, tun; 1004 int sock; 1005 1006 mode = packet_get_int(); 1007 switch (mode) { 1008 case SSH_TUNMODE_POINTOPOINT: 1009 case SSH_TUNMODE_ETHERNET: 1010 break; 1011 default: 1012 packet_send_debug("Unsupported tunnel device mode."); 1013 return NULL; 1014 } 1015 if ((options.permit_tun & mode) == 0) { 1016 packet_send_debug("Server has rejected tunnel device " 1017 "forwarding"); 1018 return NULL; 1019 } 1020 1021 tun = packet_get_int(); 1022 if (forced_tun_device != -1) { 1023 if (tun != SSH_TUNID_ANY && forced_tun_device != tun) 1024 goto done; 1025 tun = forced_tun_device; 1026 } 1027 sock = tun_open(tun, mode); 1028 if (sock < 0) 1029 goto done; 1030 if (options.hpn_disabled) 1031 c = channel_new("tun", SSH_CHANNEL_OPEN, sock, sock, -1, 1032 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1); 1033 else 1034 c = channel_new("tun", SSH_CHANNEL_OPEN, sock, sock, -1, 1035 options.hpn_buffer_size, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1); 1036 c->datagram = 1; 1037 #if defined(SSH_TUN_FILTER) 1038 if (mode == SSH_TUNMODE_POINTOPOINT) 1039 channel_register_filter(c->self, sys_tun_infilter, 1040 sys_tun_outfilter, NULL, NULL); 1041 #endif 1042 1043 done: 1044 if (c == NULL) 1045 packet_send_debug("Failed to open the tunnel device."); 1046 return c; 1047 } 1048 1049 static Channel * 1050 server_request_session(void) 1051 { 1052 Channel *c; 1053 1054 debug("input_session_request"); 1055 packet_check_eom(); 1056 1057 if (no_more_sessions) { 1058 packet_disconnect("Possible attack: attempt to open a session " 1059 "after additional sessions disabled"); 1060 } 1061 1062 /* 1063 * A server session has no fd to read or write until a 1064 * CHANNEL_REQUEST for a shell is made, so we set the type to 1065 * SSH_CHANNEL_LARVAL. Additionally, a callback for handling all 1066 * CHANNEL_REQUEST messages is registered. 1067 */ 1068 c = channel_new("session", SSH_CHANNEL_LARVAL, 1069 -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT, 1070 0, "server-session", 1); 1071 if ((options.tcp_rcv_buf_poll) && (!options.hpn_disabled)) 1072 c->dynamic_window = 1; 1073 if (session_open(the_authctxt, c->self) != 1) { 1074 debug("session open failed, free channel %d", c->self); 1075 channel_free(c); 1076 return NULL; 1077 } 1078 channel_register_cleanup(c->self, session_close_by_channel, 0); 1079 return c; 1080 } 1081 1082 static void 1083 server_input_channel_open(int type, u_int32_t seq, void *ctxt) 1084 { 1085 Channel *c = NULL; 1086 char *ctype; 1087 int rchan; 1088 u_int rmaxpack, rwindow, len; 1089 1090 ctype = packet_get_string(&len); 1091 rchan = packet_get_int(); 1092 rwindow = packet_get_int(); 1093 rmaxpack = packet_get_int(); 1094 1095 debug("server_input_channel_open: ctype %s rchan %d win %d max %d", 1096 ctype, rchan, rwindow, rmaxpack); 1097 1098 if (strcmp(ctype, "session") == 0) { 1099 c = server_request_session(); 1100 } else if (strcmp(ctype, "direct-tcpip") == 0) { 1101 c = server_request_direct_tcpip(); 1102 } else if (strcmp(ctype, "tun@openssh.com") == 0) { 1103 c = server_request_tun(); 1104 } 1105 if (c != NULL) { 1106 debug("server_input_channel_open: confirm %s", ctype); 1107 c->remote_id = rchan; 1108 c->remote_window = rwindow; 1109 c->remote_maxpacket = rmaxpack; 1110 if (c->type != SSH_CHANNEL_CONNECTING) { 1111 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION); 1112 packet_put_int(c->remote_id); 1113 packet_put_int(c->self); 1114 packet_put_int(c->local_window); 1115 packet_put_int(c->local_maxpacket); 1116 packet_send(); 1117 } 1118 } else { 1119 debug("server_input_channel_open: failure %s", ctype); 1120 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE); 1121 packet_put_int(rchan); 1122 packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED); 1123 if (!(datafellows & SSH_BUG_OPENFAILURE)) { 1124 packet_put_cstring("open failed"); 1125 packet_put_cstring(""); 1126 } 1127 packet_send(); 1128 } 1129 xfree(ctype); 1130 } 1131 1132 static void 1133 server_input_global_request(int type, u_int32_t seq, void *ctxt) 1134 { 1135 char *rtype; 1136 int want_reply; 1137 int success = 0, allocated_listen_port = 0; 1138 1139 rtype = packet_get_string(NULL); 1140 want_reply = packet_get_char(); 1141 debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply); 1142 1143 /* -R style forwarding */ 1144 if (strcmp(rtype, "tcpip-forward") == 0) { 1145 struct passwd *pw; 1146 char *listen_address; 1147 u_short listen_port; 1148 1149 pw = the_authctxt->pw; 1150 if (pw == NULL || !the_authctxt->valid) 1151 fatal("server_input_global_request: no/invalid user"); 1152 listen_address = packet_get_string(NULL); 1153 listen_port = (u_short)packet_get_int(); 1154 debug("server_input_global_request: tcpip-forward listen %s port %d", 1155 listen_address, listen_port); 1156 1157 /* check permissions */ 1158 if (!options.allow_tcp_forwarding || 1159 no_port_forwarding_flag || 1160 (!want_reply && listen_port == 0) 1161 #ifndef NO_IPPORT_RESERVED_CONCEPT 1162 || (listen_port != 0 && listen_port < IPPORT_RESERVED && 1163 pw->pw_uid != 0) 1164 #endif 1165 ) { 1166 success = 0; 1167 packet_send_debug("Server has disabled port forwarding."); 1168 } else { 1169 /* Start listening on the port */ 1170 success = channel_setup_remote_fwd_listener( 1171 listen_address, listen_port, 1172 &allocated_listen_port, options.gateway_ports); 1173 } 1174 xfree(listen_address); 1175 } else if (strcmp(rtype, "cancel-tcpip-forward") == 0) { 1176 char *cancel_address; 1177 u_short cancel_port; 1178 1179 cancel_address = packet_get_string(NULL); 1180 cancel_port = (u_short)packet_get_int(); 1181 debug("%s: cancel-tcpip-forward addr %s port %d", __func__, 1182 cancel_address, cancel_port); 1183 1184 success = channel_cancel_rport_listener(cancel_address, 1185 cancel_port); 1186 xfree(cancel_address); 1187 } else if (strcmp(rtype, "no-more-sessions@openssh.com") == 0) { 1188 no_more_sessions = 1; 1189 success = 1; 1190 } 1191 if (want_reply) { 1192 packet_start(success ? 1193 SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE); 1194 if (success && allocated_listen_port > 0) 1195 packet_put_int(allocated_listen_port); 1196 packet_send(); 1197 packet_write_wait(); 1198 } 1199 xfree(rtype); 1200 } 1201 1202 static void 1203 server_input_channel_req(int type, u_int32_t seq, void *ctxt) 1204 { 1205 Channel *c; 1206 int id, reply, success = 0; 1207 char *rtype; 1208 1209 id = packet_get_int(); 1210 rtype = packet_get_string(NULL); 1211 reply = packet_get_char(); 1212 1213 debug("server_input_channel_req: channel %d request %s reply %d", 1214 id, rtype, reply); 1215 1216 if ((c = channel_lookup(id)) == NULL) 1217 packet_disconnect("server_input_channel_req: " 1218 "unknown channel %d", id); 1219 if (!strcmp(rtype, "eow@openssh.com")) { 1220 packet_check_eom(); 1221 chan_rcvd_eow(c); 1222 } else if ((c->type == SSH_CHANNEL_LARVAL || 1223 c->type == SSH_CHANNEL_OPEN) && strcmp(c->ctype, "session") == 0) 1224 success = session_input_channel_req(c, rtype); 1225 if (reply) { 1226 packet_start(success ? 1227 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE); 1228 packet_put_int(c->remote_id); 1229 packet_send(); 1230 } 1231 xfree(rtype); 1232 } 1233 1234 static void 1235 server_init_dispatch_20(void) 1236 { 1237 debug("server_init_dispatch_20"); 1238 dispatch_init(&dispatch_protocol_error); 1239 dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); 1240 dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data); 1241 dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); 1242 dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); 1243 dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open); 1244 dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 1245 dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 1246 dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req); 1247 dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); 1248 dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request); 1249 /* client_alive */ 1250 dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &server_input_keep_alive); 1251 dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_keep_alive); 1252 dispatch_set(SSH2_MSG_REQUEST_SUCCESS, &server_input_keep_alive); 1253 dispatch_set(SSH2_MSG_REQUEST_FAILURE, &server_input_keep_alive); 1254 /* rekeying */ 1255 dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); 1256 } 1257 static void 1258 server_init_dispatch_13(void) 1259 { 1260 debug("server_init_dispatch_13"); 1261 dispatch_init(NULL); 1262 dispatch_set(SSH_CMSG_EOF, &server_input_eof); 1263 dispatch_set(SSH_CMSG_STDIN_DATA, &server_input_stdin_data); 1264 dispatch_set(SSH_CMSG_WINDOW_SIZE, &server_input_window_size); 1265 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close); 1266 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation); 1267 dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data); 1268 dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 1269 dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 1270 dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open); 1271 } 1272 static void 1273 server_init_dispatch_15(void) 1274 { 1275 server_init_dispatch_13(); 1276 debug("server_init_dispatch_15"); 1277 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof); 1278 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_oclose); 1279 } 1280 static void 1281 server_init_dispatch(void) 1282 { 1283 if (compat20) 1284 server_init_dispatch_20(); 1285 else if (compat13) 1286 server_init_dispatch_13(); 1287 else 1288 server_init_dispatch_15(); 1289 } 1290