1 /* $NetBSD: serverloop.c,v 1.2 2009/06/07 22:38:47 christos Exp $ */ 2 /* $OpenBSD: serverloop.c,v 1.157 2009/02/12 03:16:01 djm Exp $ */ 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 __RCSID("$NetBSD: serverloop.c,v 1.2 2009/06/07 22:38:47 christos Exp $"); 41 #include <sys/types.h> 42 #include <sys/wait.h> 43 #include <sys/socket.h> 44 #include <sys/time.h> 45 #include <sys/param.h> 46 #include <sys/queue.h> 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 "xmalloc.h" 60 #include "packet.h" 61 #include "buffer.h" 62 #include "log.h" 63 #include "servconf.h" 64 #include "canohost.h" 65 #include "sshpty.h" 66 #include "channels.h" 67 #include "compat.h" 68 #include "ssh1.h" 69 #include "ssh2.h" 70 #include "key.h" 71 #include "cipher.h" 72 #include "kex.h" 73 #include "hostfile.h" 74 #include "auth.h" 75 #include "session.h" 76 #include "dispatch.h" 77 #include "auth-options.h" 78 #include "serverloop.h" 79 #include "misc.h" 80 81 extern ServerOptions options; 82 83 /* XXX */ 84 extern Kex *xxx_kex; 85 extern Authctxt *the_authctxt; 86 extern int use_privsep; 87 88 static Buffer stdin_buffer; /* Buffer for stdin data. */ 89 static Buffer stdout_buffer; /* Buffer for stdout data. */ 90 static Buffer stderr_buffer; /* Buffer for stderr data. */ 91 static int fdin; /* Descriptor for stdin (for writing) */ 92 static int fdout; /* Descriptor for stdout (for reading); 93 May be same number as fdin. */ 94 static int fderr; /* Descriptor for stderr. May be -1. */ 95 static u_long stdin_bytes = 0; /* Number of bytes written to stdin. */ 96 static u_long stdout_bytes = 0; /* Number of stdout bytes sent to client. */ 97 static u_long stderr_bytes = 0; /* Number of stderr bytes sent to client. */ 98 static u_long fdout_bytes = 0; /* Number of stdout bytes read from program. */ 99 static int stdin_eof = 0; /* EOF message received from client. */ 100 static int fdout_eof = 0; /* EOF encountered reading from fdout. */ 101 static int fderr_eof = 0; /* EOF encountered readung from fderr. */ 102 static int fdin_is_tty = 0; /* fdin points to a tty. */ 103 static int connection_in; /* Connection to client (input). */ 104 static int connection_out; /* Connection to client (output). */ 105 static int connection_closed = 0; /* Connection to client closed. */ 106 static u_int buffer_high; /* "Soft" max buffer size. */ 107 static int no_more_sessions = 0; /* Disallow further sessions. */ 108 109 /* 110 * This SIGCHLD kludge is used to detect when the child exits. The server 111 * will exit after that, as soon as forwarded connections have terminated. 112 */ 113 114 static volatile sig_atomic_t child_terminated = 0; /* The child has terminated. */ 115 116 /* Cleanup on signals (!use_privsep case only) */ 117 static volatile sig_atomic_t received_sigterm = 0; 118 119 /* prototypes */ 120 static void server_init_dispatch(void); 121 122 /* 123 * Returns current time in seconds from Jan 1, 1970 with the maximum 124 * available resolution. 125 */ 126 127 static double 128 get_current_time(void) 129 { 130 struct timeval tv; 131 gettimeofday(&tv, NULL); 132 return (double) tv.tv_sec + (double) tv.tv_usec / 1000000.0; 133 } 134 135 /* 136 * we write to this pipe if a SIGCHLD is caught in order to avoid 137 * the race between select() and child_terminated 138 */ 139 static int notify_pipe[2]; 140 static void 141 notify_setup(void) 142 { 143 if (pipe(notify_pipe) < 0) { 144 error("pipe(notify_pipe) failed %s", strerror(errno)); 145 } else if ((fcntl(notify_pipe[0], F_SETFD, 1) == -1) || 146 (fcntl(notify_pipe[1], F_SETFD, 1) == -1)) { 147 error("fcntl(notify_pipe, F_SETFD) failed %s", strerror(errno)); 148 close(notify_pipe[0]); 149 close(notify_pipe[1]); 150 } else { 151 set_nonblock(notify_pipe[0]); 152 set_nonblock(notify_pipe[1]); 153 return; 154 } 155 notify_pipe[0] = -1; /* read end */ 156 notify_pipe[1] = -1; /* write end */ 157 } 158 static void 159 notify_parent(void) 160 { 161 if (notify_pipe[1] != -1) 162 write(notify_pipe[1], "", 1); 163 } 164 static void 165 notify_prepare(fd_set *readset) 166 { 167 if (notify_pipe[0] != -1) 168 FD_SET(notify_pipe[0], readset); 169 } 170 static void 171 notify_done(fd_set *readset) 172 { 173 char c; 174 175 if (notify_pipe[0] != -1 && FD_ISSET(notify_pipe[0], readset)) 176 while (read(notify_pipe[0], &c, 1) != -1) 177 debug2("notify_done: reading"); 178 } 179 180 /*ARGSUSED*/ 181 static void 182 sigchld_handler(int sig) 183 { 184 int save_errno = errno; 185 child_terminated = 1; 186 signal(SIGCHLD, sigchld_handler); 187 notify_parent(); 188 errno = save_errno; 189 } 190 191 /*ARGSUSED*/ 192 static void 193 sigterm_handler(int sig) 194 { 195 received_sigterm = sig; 196 } 197 198 /* 199 * Make packets from buffered stderr data, and buffer it for sending 200 * to the client. 201 */ 202 static void 203 make_packets_from_stderr_data(void) 204 { 205 u_int len; 206 207 /* Send buffered stderr data to the client. */ 208 while (buffer_len(&stderr_buffer) > 0 && 209 packet_not_very_much_data_to_write()) { 210 len = buffer_len(&stderr_buffer); 211 if (packet_is_interactive()) { 212 if (len > 512) 213 len = 512; 214 } else { 215 /* Keep the packets at reasonable size. */ 216 if (len > packet_get_maxsize()) 217 len = packet_get_maxsize(); 218 } 219 packet_start(SSH_SMSG_STDERR_DATA); 220 packet_put_string(buffer_ptr(&stderr_buffer), len); 221 packet_send(); 222 buffer_consume(&stderr_buffer, len); 223 stderr_bytes += len; 224 } 225 } 226 227 /* 228 * Make packets from buffered stdout data, and buffer it for sending to the 229 * client. 230 */ 231 static void 232 make_packets_from_stdout_data(void) 233 { 234 u_int len; 235 236 /* Send buffered stdout data to the client. */ 237 while (buffer_len(&stdout_buffer) > 0 && 238 packet_not_very_much_data_to_write()) { 239 len = buffer_len(&stdout_buffer); 240 if (packet_is_interactive()) { 241 if (len > 512) 242 len = 512; 243 } else { 244 /* Keep the packets at reasonable size. */ 245 if (len > packet_get_maxsize()) 246 len = packet_get_maxsize(); 247 } 248 packet_start(SSH_SMSG_STDOUT_DATA); 249 packet_put_string(buffer_ptr(&stdout_buffer), len); 250 packet_send(); 251 buffer_consume(&stdout_buffer, len); 252 stdout_bytes += len; 253 } 254 } 255 256 static void 257 client_alive_check(void) 258 { 259 int channel_id; 260 261 /* timeout, check to see how many we have had */ 262 if (++keep_alive_timeouts > options.client_alive_count_max) { 263 logit("Timeout, client not responding."); 264 cleanup_exit(255); 265 } 266 267 /* 268 * send a bogus global/channel request with "wantreply", 269 * we should get back a failure 270 */ 271 if ((channel_id = channel_find_open()) == -1) { 272 packet_start(SSH2_MSG_GLOBAL_REQUEST); 273 packet_put_cstring("keepalive@openssh.com"); 274 packet_put_char(1); /* boolean: want reply */ 275 } else { 276 channel_request_start(channel_id, "keepalive@openssh.com", 1); 277 } 278 packet_send(); 279 } 280 281 /* 282 * Sleep in select() until we can do something. This will initialize the 283 * select masks. Upon return, the masks will indicate which descriptors 284 * have data or can accept data. Optionally, a maximum time can be specified 285 * for the duration of the wait (0 = infinite). 286 */ 287 static void 288 wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp, 289 u_int *nallocp, u_int max_time_milliseconds) 290 { 291 struct timeval tv, *tvp; 292 int ret; 293 int client_alive_scheduled = 0; 294 295 /* 296 * if using client_alive, set the max timeout accordingly, 297 * and indicate that this particular timeout was for client 298 * alive by setting the client_alive_scheduled flag. 299 * 300 * this could be randomized somewhat to make traffic 301 * analysis more difficult, but we're not doing it yet. 302 */ 303 if (compat20 && 304 max_time_milliseconds == 0 && options.client_alive_interval) { 305 client_alive_scheduled = 1; 306 max_time_milliseconds = options.client_alive_interval * 1000; 307 } 308 309 /* Allocate and update select() masks for channel descriptors. */ 310 channel_prepare_select(readsetp, writesetp, maxfdp, nallocp, 0); 311 312 if (compat20) { 313 #if 0 314 /* wrong: bad condition XXX */ 315 if (channel_not_very_much_buffered_data()) 316 #endif 317 FD_SET(connection_in, *readsetp); 318 } else { 319 /* 320 * Read packets from the client unless we have too much 321 * buffered stdin or channel data. 322 */ 323 if (buffer_len(&stdin_buffer) < buffer_high && 324 channel_not_very_much_buffered_data()) 325 FD_SET(connection_in, *readsetp); 326 /* 327 * If there is not too much data already buffered going to 328 * the client, try to get some more data from the program. 329 */ 330 if (packet_not_very_much_data_to_write()) { 331 if (!fdout_eof) 332 FD_SET(fdout, *readsetp); 333 if (!fderr_eof) 334 FD_SET(fderr, *readsetp); 335 } 336 /* 337 * If we have buffered data, try to write some of that data 338 * to the program. 339 */ 340 if (fdin != -1 && buffer_len(&stdin_buffer) > 0) 341 FD_SET(fdin, *writesetp); 342 } 343 notify_prepare(*readsetp); 344 345 /* 346 * If we have buffered packet data going to the client, mark that 347 * descriptor. 348 */ 349 if (packet_have_data_to_write()) 350 FD_SET(connection_out, *writesetp); 351 352 /* 353 * If child has terminated and there is enough buffer space to read 354 * from it, then read as much as is available and exit. 355 */ 356 if (child_terminated && packet_not_very_much_data_to_write()) 357 if (max_time_milliseconds == 0 || client_alive_scheduled) 358 max_time_milliseconds = 100; 359 360 if (max_time_milliseconds == 0) 361 tvp = NULL; 362 else { 363 tv.tv_sec = max_time_milliseconds / 1000; 364 tv.tv_usec = 1000 * (max_time_milliseconds % 1000); 365 tvp = &tv; 366 } 367 368 /* Wait for something to happen, or the timeout to expire. */ 369 ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp); 370 371 if (ret == -1) { 372 memset(*readsetp, 0, *nallocp); 373 memset(*writesetp, 0, *nallocp); 374 if (errno != EINTR) 375 error("select: %.100s", strerror(errno)); 376 } else if (ret == 0 && client_alive_scheduled) 377 client_alive_check(); 378 379 notify_done(*readsetp); 380 } 381 382 /* 383 * Processes input from the client and the program. Input data is stored 384 * in buffers and processed later. 385 */ 386 static void 387 process_input(fd_set *readset) 388 { 389 int len; 390 char buf[16384]; 391 392 /* Read and buffer any input data from the client. */ 393 if (FD_ISSET(connection_in, readset)) { 394 len = read(connection_in, buf, sizeof(buf)); 395 if (len == 0) { 396 verbose("Connection closed by %.100s", 397 get_remote_ipaddr()); 398 connection_closed = 1; 399 if (compat20) 400 return; 401 cleanup_exit(255); 402 } else if (len < 0) { 403 if (errno != EINTR && errno != EAGAIN) { 404 verbose("Read error from remote host " 405 "%.100s: %.100s", 406 get_remote_ipaddr(), strerror(errno)); 407 cleanup_exit(255); 408 } 409 } else { 410 /* Buffer any received data. */ 411 packet_process_incoming(buf, len); 412 fdout_bytes += len; 413 } 414 } 415 if (compat20) 416 return; 417 418 /* Read and buffer any available stdout data from the program. */ 419 if (!fdout_eof && FD_ISSET(fdout, readset)) { 420 len = read(fdout, buf, sizeof(buf)); 421 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 422 /* do nothing */ 423 } else if (len <= 0) { 424 fdout_eof = 1; 425 } else { 426 buffer_append(&stdout_buffer, buf, len); 427 debug ("FD out now: %ld", fdout_bytes); 428 fdout_bytes += len; 429 } 430 } 431 /* Read and buffer any available stderr data from the program. */ 432 if (!fderr_eof && FD_ISSET(fderr, readset)) { 433 len = read(fderr, buf, sizeof(buf)); 434 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 435 /* do nothing */ 436 } else if (len <= 0) { 437 fderr_eof = 1; 438 } else { 439 buffer_append(&stderr_buffer, buf, len); 440 } 441 } 442 } 443 444 /* 445 * Sends data from internal buffers to client program stdin. 446 */ 447 static void 448 process_output(fd_set *writeset) 449 { 450 struct termios tio; 451 u_char *data; 452 u_int dlen; 453 int len; 454 455 /* Write buffered data to program stdin. */ 456 if (!compat20 && fdin != -1 && FD_ISSET(fdin, writeset)) { 457 data = buffer_ptr(&stdin_buffer); 458 dlen = buffer_len(&stdin_buffer); 459 len = write(fdin, data, dlen); 460 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 461 /* do nothing */ 462 } else if (len <= 0) { 463 if (fdin != fdout) 464 close(fdin); 465 else 466 shutdown(fdin, SHUT_WR); /* We will no longer send. */ 467 fdin = -1; 468 } else { 469 /* Successful write. */ 470 if (fdin_is_tty && dlen >= 1 && data[0] != '\r' && 471 tcgetattr(fdin, &tio) == 0 && 472 !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) { 473 /* 474 * Simulate echo to reduce the impact of 475 * traffic analysis 476 */ 477 packet_send_ignore(len); 478 packet_send(); 479 } 480 /* Consume the data from the buffer. */ 481 buffer_consume(&stdin_buffer, len); 482 /* Update the count of bytes written to the program. */ 483 stdin_bytes += len; 484 } 485 } 486 /* Send any buffered packet data to the client. */ 487 if (FD_ISSET(connection_out, writeset)) 488 stdin_bytes += packet_write_poll(); 489 } 490 491 /* 492 * Wait until all buffered output has been sent to the client. 493 * This is used when the program terminates. 494 */ 495 static void 496 drain_output(void) 497 { 498 /* Send any buffered stdout data to the client. */ 499 if (buffer_len(&stdout_buffer) > 0) { 500 packet_start(SSH_SMSG_STDOUT_DATA); 501 packet_put_string(buffer_ptr(&stdout_buffer), 502 buffer_len(&stdout_buffer)); 503 packet_send(); 504 /* Update the count of sent bytes. */ 505 stdout_bytes += buffer_len(&stdout_buffer); 506 } 507 /* Send any buffered stderr data to the client. */ 508 if (buffer_len(&stderr_buffer) > 0) { 509 packet_start(SSH_SMSG_STDERR_DATA); 510 packet_put_string(buffer_ptr(&stderr_buffer), 511 buffer_len(&stderr_buffer)); 512 packet_send(); 513 /* Update the count of sent bytes. */ 514 stderr_bytes += buffer_len(&stderr_buffer); 515 } 516 /* Wait until all buffered data has been written to the client. */ 517 packet_write_wait(); 518 } 519 520 static void 521 process_buffered_input_packets(void) 522 { 523 dispatch_run(DISPATCH_NONBLOCK, NULL, compat20 ? xxx_kex : NULL); 524 } 525 526 /* 527 * Performs the interactive session. This handles data transmission between 528 * the client and the program. Note that the notion of stdin, stdout, and 529 * stderr in this function is sort of reversed: this function writes to 530 * stdin (of the child program), and reads from stdout and stderr (of the 531 * child program). 532 */ 533 void 534 server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg) 535 { 536 fd_set *readset = NULL, *writeset = NULL; 537 int max_fd = 0; 538 u_int nalloc = 0; 539 int wait_status; /* Status returned by wait(). */ 540 pid_t wait_pid; /* pid returned by wait(). */ 541 int waiting_termination = 0; /* Have displayed waiting close message. */ 542 u_int max_time_milliseconds; 543 u_int previous_stdout_buffer_bytes; 544 u_int stdout_buffer_bytes; 545 int type; 546 547 debug("Entering interactive session."); 548 549 /* Initialize the SIGCHLD kludge. */ 550 child_terminated = 0; 551 signal(SIGCHLD, sigchld_handler); 552 553 if (!use_privsep) { 554 signal(SIGTERM, sigterm_handler); 555 signal(SIGINT, sigterm_handler); 556 signal(SIGQUIT, sigterm_handler); 557 } 558 559 /* Initialize our global variables. */ 560 fdin = fdin_arg; 561 fdout = fdout_arg; 562 fderr = fderr_arg; 563 564 /* nonblocking IO */ 565 set_nonblock(fdin); 566 set_nonblock(fdout); 567 /* we don't have stderr for interactive terminal sessions, see below */ 568 if (fderr != -1) 569 set_nonblock(fderr); 570 571 if (!(datafellows & SSH_BUG_IGNOREMSG) && isatty(fdin)) 572 fdin_is_tty = 1; 573 574 connection_in = packet_get_connection_in(); 575 connection_out = packet_get_connection_out(); 576 577 notify_setup(); 578 579 previous_stdout_buffer_bytes = 0; 580 581 /* Set approximate I/O buffer size. */ 582 if (packet_is_interactive()) 583 buffer_high = 4096; 584 else 585 buffer_high = 64 * 1024; 586 587 #if 0 588 /* Initialize max_fd to the maximum of the known file descriptors. */ 589 max_fd = MAX(connection_in, connection_out); 590 max_fd = MAX(max_fd, fdin); 591 max_fd = MAX(max_fd, fdout); 592 if (fderr != -1) 593 max_fd = MAX(max_fd, fderr); 594 #endif 595 596 /* Initialize Initialize buffers. */ 597 buffer_init(&stdin_buffer); 598 buffer_init(&stdout_buffer); 599 buffer_init(&stderr_buffer); 600 601 /* 602 * If we have no separate fderr (which is the case when we have a pty 603 * - there we cannot make difference between data sent to stdout and 604 * stderr), indicate that we have seen an EOF from stderr. This way 605 * we don't need to check the descriptor everywhere. 606 */ 607 if (fderr == -1) 608 fderr_eof = 1; 609 610 server_init_dispatch(); 611 612 /* Main loop of the server for the interactive session mode. */ 613 for (;;) { 614 615 /* Process buffered packets from the client. */ 616 process_buffered_input_packets(); 617 618 /* 619 * If we have received eof, and there is no more pending 620 * input data, cause a real eof by closing fdin. 621 */ 622 if (stdin_eof && fdin != -1 && buffer_len(&stdin_buffer) == 0) { 623 if (fdin != fdout) 624 close(fdin); 625 else 626 shutdown(fdin, SHUT_WR); /* We will no longer send. */ 627 fdin = -1; 628 } 629 /* Make packets from buffered stderr data to send to the client. */ 630 make_packets_from_stderr_data(); 631 632 /* 633 * Make packets from buffered stdout data to send to the 634 * client. If there is very little to send, this arranges to 635 * not send them now, but to wait a short while to see if we 636 * are getting more data. This is necessary, as some systems 637 * wake up readers from a pty after each separate character. 638 */ 639 max_time_milliseconds = 0; 640 stdout_buffer_bytes = buffer_len(&stdout_buffer); 641 if (stdout_buffer_bytes != 0 && stdout_buffer_bytes < 256 && 642 stdout_buffer_bytes != previous_stdout_buffer_bytes) { 643 /* try again after a while */ 644 max_time_milliseconds = 10; 645 } else { 646 /* Send it now. */ 647 make_packets_from_stdout_data(); 648 } 649 previous_stdout_buffer_bytes = buffer_len(&stdout_buffer); 650 651 /* Send channel data to the client. */ 652 if (packet_not_very_much_data_to_write()) 653 channel_output_poll(); 654 655 /* 656 * Bail out of the loop if the program has closed its output 657 * descriptors, and we have no more data to send to the 658 * client, and there is no pending buffered data. 659 */ 660 if (fdout_eof && fderr_eof && !packet_have_data_to_write() && 661 buffer_len(&stdout_buffer) == 0 && buffer_len(&stderr_buffer) == 0) { 662 if (!channel_still_open()) 663 break; 664 if (!waiting_termination) { 665 const char *s = "Waiting for forwarded connections to terminate...\r\n"; 666 char *cp; 667 waiting_termination = 1; 668 buffer_append(&stderr_buffer, s, strlen(s)); 669 670 /* Display list of open channels. */ 671 cp = channel_open_message(); 672 buffer_append(&stderr_buffer, cp, strlen(cp)); 673 xfree(cp); 674 } 675 } 676 max_fd = MAX(connection_in, connection_out); 677 max_fd = MAX(max_fd, fdin); 678 max_fd = MAX(max_fd, fdout); 679 max_fd = MAX(max_fd, fderr); 680 max_fd = MAX(max_fd, notify_pipe[0]); 681 682 /* Sleep in select() until we can do something. */ 683 wait_until_can_do_something(&readset, &writeset, &max_fd, 684 &nalloc, max_time_milliseconds); 685 686 if (received_sigterm) { 687 logit("Exiting on signal %ld", (long)received_sigterm); 688 /* Clean up sessions, utmp, etc. */ 689 cleanup_exit(255); 690 } 691 692 /* Process any channel events. */ 693 channel_after_select(readset, writeset); 694 695 /* Process input from the client and from program stdout/stderr. */ 696 process_input(readset); 697 698 /* Process output to the client and to program stdin. */ 699 process_output(writeset); 700 } 701 if (readset) 702 xfree(readset); 703 if (writeset) 704 xfree(writeset); 705 706 /* Cleanup and termination code. */ 707 708 /* Wait until all output has been sent to the client. */ 709 drain_output(); 710 711 debug("End of interactive session; stdin %ld, stdout (read %ld, sent %ld), stderr %ld bytes.", 712 stdin_bytes, fdout_bytes, stdout_bytes, stderr_bytes); 713 714 /* Free and clear the buffers. */ 715 buffer_free(&stdin_buffer); 716 buffer_free(&stdout_buffer); 717 buffer_free(&stderr_buffer); 718 719 /* Close the file descriptors. */ 720 if (fdout != -1) 721 close(fdout); 722 fdout = -1; 723 fdout_eof = 1; 724 if (fderr != -1) 725 close(fderr); 726 fderr = -1; 727 fderr_eof = 1; 728 if (fdin != -1) 729 close(fdin); 730 fdin = -1; 731 732 channel_free_all(); 733 734 /* We no longer want our SIGCHLD handler to be called. */ 735 signal(SIGCHLD, SIG_DFL); 736 737 while ((wait_pid = waitpid(-1, &wait_status, 0)) < 0) 738 if (errno != EINTR) 739 packet_disconnect("wait: %.100s", strerror(errno)); 740 if (wait_pid != pid) 741 error("Strange, wait returned pid %ld, expected %ld", 742 (long)wait_pid, (long)pid); 743 744 /* Check if it exited normally. */ 745 if (WIFEXITED(wait_status)) { 746 /* Yes, normal exit. Get exit status and send it to the client. */ 747 debug("Command exited with status %d.", WEXITSTATUS(wait_status)); 748 packet_start(SSH_SMSG_EXITSTATUS); 749 packet_put_int(WEXITSTATUS(wait_status)); 750 packet_send(); 751 packet_write_wait(); 752 753 /* 754 * Wait for exit confirmation. Note that there might be 755 * other packets coming before it; however, the program has 756 * already died so we just ignore them. The client is 757 * supposed to respond with the confirmation when it receives 758 * the exit status. 759 */ 760 do { 761 type = packet_read(); 762 } 763 while (type != SSH_CMSG_EXIT_CONFIRMATION); 764 765 debug("Received exit confirmation."); 766 return; 767 } 768 /* Check if the program terminated due to a signal. */ 769 if (WIFSIGNALED(wait_status)) 770 packet_disconnect("Command terminated on signal %d.", 771 WTERMSIG(wait_status)); 772 773 /* Some weird exit cause. Just exit. */ 774 packet_disconnect("wait returned status %04x.", wait_status); 775 /* NOTREACHED */ 776 } 777 778 static void 779 collect_children(void) 780 { 781 pid_t pid; 782 sigset_t oset, nset; 783 int status; 784 785 /* block SIGCHLD while we check for dead children */ 786 sigemptyset(&nset); 787 sigaddset(&nset, SIGCHLD); 788 sigprocmask(SIG_BLOCK, &nset, &oset); 789 if (child_terminated) { 790 debug("Received SIGCHLD."); 791 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 792 (pid < 0 && errno == EINTR)) 793 if (pid > 0) 794 session_close_by_pid(pid, status); 795 child_terminated = 0; 796 } 797 sigprocmask(SIG_SETMASK, &oset, NULL); 798 } 799 800 void 801 server_loop2(Authctxt *authctxt) 802 { 803 fd_set *readset = NULL, *writeset = NULL; 804 int rekeying = 0, max_fd; 805 u_int nalloc = 0; 806 double start_time, total_time; 807 808 debug("Entering interactive session for SSH2."); 809 start_time = get_current_time(); 810 811 signal(SIGCHLD, sigchld_handler); 812 child_terminated = 0; 813 connection_in = packet_get_connection_in(); 814 connection_out = packet_get_connection_out(); 815 816 if (!use_privsep) { 817 signal(SIGTERM, sigterm_handler); 818 signal(SIGINT, sigterm_handler); 819 signal(SIGQUIT, sigterm_handler); 820 } 821 822 notify_setup(); 823 824 max_fd = MAX(connection_in, connection_out); 825 max_fd = MAX(max_fd, notify_pipe[0]); 826 827 server_init_dispatch(); 828 829 for (;;) { 830 process_buffered_input_packets(); 831 832 rekeying = (xxx_kex != NULL && !xxx_kex->done); 833 834 if (!rekeying && packet_not_very_much_data_to_write()) 835 channel_output_poll(); 836 wait_until_can_do_something(&readset, &writeset, &max_fd, 837 &nalloc, 0); 838 839 if (received_sigterm) { 840 logit("Exiting on signal %ld", (long)received_sigterm); 841 /* Clean up sessions, utmp, etc. */ 842 cleanup_exit(255); 843 } 844 845 collect_children(); 846 if (!rekeying) { 847 channel_after_select(readset, writeset); 848 if (packet_need_rekeying()) { 849 debug("need rekeying"); 850 xxx_kex->done = 0; 851 kex_send_kexinit(xxx_kex); 852 } 853 } 854 process_input(readset); 855 if (connection_closed) 856 break; 857 process_output(writeset); 858 } 859 collect_children(); 860 861 if (readset) 862 xfree(readset); 863 if (writeset) 864 xfree(writeset); 865 866 /* free all channels, no more reads and writes */ 867 channel_free_all(); 868 869 /* free remaining sessions, e.g. remove wtmp entries */ 870 session_destroy_all(NULL); 871 total_time = get_current_time() - start_time; 872 logit("SSH: Server;LType: Throughput;Remote: %s-%d;IN: %lu;OUT: %lu;Duration: %.1f;tPut_in: %.1f;tPut_out: %.1f", 873 get_remote_ipaddr(), get_remote_port(), 874 stdin_bytes, fdout_bytes, total_time, stdin_bytes / total_time, 875 fdout_bytes / total_time); 876 } 877 878 static void 879 server_input_keep_alive(int type, u_int32_t seq, void *ctxt) 880 { 881 debug("Got %d/%u for keepalive", type, seq); 882 /* 883 * reset timeout, since we got a sane answer from the client. 884 * even if this was generated by something other than 885 * the bogus CHANNEL_REQUEST we send for keepalives. 886 */ 887 keep_alive_timeouts = 0; 888 } 889 890 static void 891 server_input_stdin_data(int type, u_int32_t seq, void *ctxt) 892 { 893 char *data; 894 u_int data_len; 895 896 /* Stdin data from the client. Append it to the buffer. */ 897 /* Ignore any data if the client has closed stdin. */ 898 if (fdin == -1) 899 return; 900 data = packet_get_string(&data_len); 901 packet_check_eom(); 902 buffer_append(&stdin_buffer, data, data_len); 903 memset(data, 0, data_len); 904 xfree(data); 905 } 906 907 static void 908 server_input_eof(int type, u_int32_t seq, void *ctxt) 909 { 910 /* 911 * Eof from the client. The stdin descriptor to the 912 * program will be closed when all buffered data has 913 * drained. 914 */ 915 debug("EOF received for stdin."); 916 packet_check_eom(); 917 stdin_eof = 1; 918 } 919 920 static void 921 server_input_window_size(int type, u_int32_t seq, void *ctxt) 922 { 923 u_int row = packet_get_int(); 924 u_int col = packet_get_int(); 925 u_int xpixel = packet_get_int(); 926 u_int ypixel = packet_get_int(); 927 928 debug("Window change received."); 929 packet_check_eom(); 930 if (fdin != -1) 931 pty_change_window_size(fdin, row, col, xpixel, ypixel); 932 } 933 934 static Channel * 935 server_request_direct_tcpip(void) 936 { 937 Channel *c; 938 char *target, *originator; 939 u_short target_port, originator_port; 940 941 target = packet_get_string(NULL); 942 target_port = packet_get_int(); 943 originator = packet_get_string(NULL); 944 originator_port = packet_get_int(); 945 packet_check_eom(); 946 947 debug("server_request_direct_tcpip: originator %s port %d, target %s " 948 "port %d", originator, originator_port, target, target_port); 949 950 /* XXX check permission */ 951 c = channel_connect_to(target, target_port, 952 "direct-tcpip", "direct-tcpip"); 953 954 xfree(originator); 955 xfree(target); 956 957 return c; 958 } 959 960 static Channel * 961 server_request_tun(void) 962 { 963 Channel *c = NULL; 964 int mode, tun; 965 int sock; 966 967 mode = packet_get_int(); 968 switch (mode) { 969 case SSH_TUNMODE_POINTOPOINT: 970 case SSH_TUNMODE_ETHERNET: 971 break; 972 default: 973 packet_send_debug("Unsupported tunnel device mode."); 974 return NULL; 975 } 976 if ((options.permit_tun & mode) == 0) { 977 packet_send_debug("Server has rejected tunnel device " 978 "forwarding"); 979 return NULL; 980 } 981 982 tun = packet_get_int(); 983 if (forced_tun_device != -1) { 984 if (tun != SSH_TUNID_ANY && forced_tun_device != tun) 985 goto done; 986 tun = forced_tun_device; 987 } 988 sock = tun_open(tun, mode); 989 if (sock < 0) 990 goto done; 991 if (options.hpn_disabled) 992 c = channel_new("tun", SSH_CHANNEL_OPEN, sock, sock, -1, 993 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1); 994 else 995 c = channel_new("tun", SSH_CHANNEL_OPEN, sock, sock, -1, 996 options.hpn_buffer_size, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1); 997 c->datagram = 1; 998 999 done: 1000 if (c == NULL) 1001 packet_send_debug("Failed to open the tunnel device."); 1002 return c; 1003 } 1004 1005 static Channel * 1006 server_request_session(void) 1007 { 1008 Channel *c; 1009 1010 debug("input_session_request"); 1011 packet_check_eom(); 1012 1013 if (no_more_sessions) { 1014 packet_disconnect("Possible attack: attempt to open a session " 1015 "after additional sessions disabled"); 1016 } 1017 1018 /* 1019 * A server session has no fd to read or write until a 1020 * CHANNEL_REQUEST for a shell is made, so we set the type to 1021 * SSH_CHANNEL_LARVAL. Additionally, a callback for handling all 1022 * CHANNEL_REQUEST messages is registered. 1023 */ 1024 c = channel_new("session", SSH_CHANNEL_LARVAL, 1025 -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT, 1026 0, "server-session", 1); 1027 if ((options.tcp_rcv_buf_poll > 0) && (!options.hpn_disabled)) 1028 c->dynamic_window = 1; 1029 if (session_open(the_authctxt, c->self) != 1) { 1030 debug("session open failed, free channel %d", c->self); 1031 channel_free(c); 1032 return NULL; 1033 } 1034 channel_register_cleanup(c->self, session_close_by_channel, 0); 1035 return c; 1036 } 1037 1038 static void 1039 server_input_channel_open(int type, u_int32_t seq, void *ctxt) 1040 { 1041 Channel *c = NULL; 1042 char *ctype; 1043 int rchan; 1044 u_int rmaxpack, rwindow, len; 1045 1046 ctype = packet_get_string(&len); 1047 rchan = packet_get_int(); 1048 rwindow = packet_get_int(); 1049 rmaxpack = packet_get_int(); 1050 1051 debug("server_input_channel_open: ctype %s rchan %d win %d max %d", 1052 ctype, rchan, rwindow, rmaxpack); 1053 1054 if (strcmp(ctype, "session") == 0) { 1055 c = server_request_session(); 1056 } else if (strcmp(ctype, "direct-tcpip") == 0) { 1057 c = server_request_direct_tcpip(); 1058 } else if (strcmp(ctype, "tun@openssh.com") == 0) { 1059 c = server_request_tun(); 1060 } 1061 if (c != NULL) { 1062 debug("server_input_channel_open: confirm %s", ctype); 1063 c->remote_id = rchan; 1064 c->remote_window = rwindow; 1065 c->remote_maxpacket = rmaxpack; 1066 if (c->type != SSH_CHANNEL_CONNECTING) { 1067 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION); 1068 packet_put_int(c->remote_id); 1069 packet_put_int(c->self); 1070 packet_put_int(c->local_window); 1071 packet_put_int(c->local_maxpacket); 1072 packet_send(); 1073 } 1074 } else { 1075 debug("server_input_channel_open: failure %s", ctype); 1076 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE); 1077 packet_put_int(rchan); 1078 packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED); 1079 if (!(datafellows & SSH_BUG_OPENFAILURE)) { 1080 packet_put_cstring("open failed"); 1081 packet_put_cstring(""); 1082 } 1083 packet_send(); 1084 } 1085 xfree(ctype); 1086 } 1087 1088 static void 1089 server_input_global_request(int type, u_int32_t seq, void *ctxt) 1090 { 1091 char *rtype; 1092 int want_reply; 1093 int success = 0, allocated_listen_port = 0; 1094 1095 rtype = packet_get_string(NULL); 1096 want_reply = packet_get_char(); 1097 debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply); 1098 1099 /* -R style forwarding */ 1100 if (strcmp(rtype, "tcpip-forward") == 0) { 1101 struct passwd *pw; 1102 char *listen_address; 1103 u_short listen_port; 1104 1105 pw = the_authctxt->pw; 1106 if (pw == NULL || !the_authctxt->valid) 1107 fatal("server_input_global_request: no/invalid user"); 1108 listen_address = packet_get_string(NULL); 1109 listen_port = (u_short)packet_get_int(); 1110 debug("server_input_global_request: tcpip-forward listen %s port %d", 1111 listen_address, listen_port); 1112 1113 /* check permissions */ 1114 if (!options.allow_tcp_forwarding || 1115 no_port_forwarding_flag || 1116 (!want_reply && listen_port == 0) || 1117 (listen_port != 0 && listen_port < IPPORT_RESERVED && 1118 pw->pw_uid != 0)) { 1119 success = 0; 1120 packet_send_debug("Server has disabled port forwarding."); 1121 } else { 1122 /* Start listening on the port */ 1123 success = channel_setup_remote_fwd_listener( 1124 listen_address, listen_port, 1125 &allocated_listen_port, options.gateway_ports); 1126 } 1127 xfree(listen_address); 1128 } else if (strcmp(rtype, "cancel-tcpip-forward") == 0) { 1129 char *cancel_address; 1130 u_short cancel_port; 1131 1132 cancel_address = packet_get_string(NULL); 1133 cancel_port = (u_short)packet_get_int(); 1134 debug("%s: cancel-tcpip-forward addr %s port %d", __func__, 1135 cancel_address, cancel_port); 1136 1137 success = channel_cancel_rport_listener(cancel_address, 1138 cancel_port); 1139 xfree(cancel_address); 1140 } else if (strcmp(rtype, "no-more-sessions@openssh.com") == 0) { 1141 no_more_sessions = 1; 1142 success = 1; 1143 } 1144 if (want_reply) { 1145 packet_start(success ? 1146 SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE); 1147 if (success && allocated_listen_port > 0) 1148 packet_put_int(allocated_listen_port); 1149 packet_send(); 1150 packet_write_wait(); 1151 } 1152 xfree(rtype); 1153 } 1154 1155 static void 1156 server_input_channel_req(int type, u_int32_t seq, void *ctxt) 1157 { 1158 Channel *c; 1159 int id, reply, success = 0; 1160 char *rtype; 1161 1162 id = packet_get_int(); 1163 rtype = packet_get_string(NULL); 1164 reply = packet_get_char(); 1165 1166 debug("server_input_channel_req: channel %d request %s reply %d", 1167 id, rtype, reply); 1168 1169 if ((c = channel_lookup(id)) == NULL) 1170 packet_disconnect("server_input_channel_req: " 1171 "unknown channel %d", id); 1172 if (!strcmp(rtype, "eow@openssh.com")) { 1173 packet_check_eom(); 1174 chan_rcvd_eow(c); 1175 } else if ((c->type == SSH_CHANNEL_LARVAL || 1176 c->type == SSH_CHANNEL_OPEN) && strcmp(c->ctype, "session") == 0) 1177 success = session_input_channel_req(c, rtype); 1178 if (reply) { 1179 packet_start(success ? 1180 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE); 1181 packet_put_int(c->remote_id); 1182 packet_send(); 1183 } 1184 xfree(rtype); 1185 } 1186 1187 static void 1188 server_init_dispatch_20(void) 1189 { 1190 debug("server_init_dispatch_20"); 1191 dispatch_init(&dispatch_protocol_error); 1192 dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); 1193 dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data); 1194 dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); 1195 dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); 1196 dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open); 1197 dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 1198 dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 1199 dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req); 1200 dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); 1201 dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request); 1202 /* client_alive */ 1203 dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &server_input_keep_alive); 1204 dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_keep_alive); 1205 dispatch_set(SSH2_MSG_REQUEST_SUCCESS, &server_input_keep_alive); 1206 dispatch_set(SSH2_MSG_REQUEST_FAILURE, &server_input_keep_alive); 1207 /* rekeying */ 1208 dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); 1209 } 1210 static void 1211 server_init_dispatch_13(void) 1212 { 1213 debug("server_init_dispatch_13"); 1214 dispatch_init(NULL); 1215 dispatch_set(SSH_CMSG_EOF, &server_input_eof); 1216 dispatch_set(SSH_CMSG_STDIN_DATA, &server_input_stdin_data); 1217 dispatch_set(SSH_CMSG_WINDOW_SIZE, &server_input_window_size); 1218 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close); 1219 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation); 1220 dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data); 1221 dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 1222 dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 1223 dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open); 1224 } 1225 static void 1226 server_init_dispatch_15(void) 1227 { 1228 server_init_dispatch_13(); 1229 debug("server_init_dispatch_15"); 1230 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof); 1231 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_oclose); 1232 } 1233 static void 1234 server_init_dispatch(void) 1235 { 1236 if (compat20) 1237 server_init_dispatch_20(); 1238 else if (compat13) 1239 server_init_dispatch_13(); 1240 else 1241 server_init_dispatch_15(); 1242 } 1243