1 /* $NetBSD: serverloop.c,v 1.3 2009/12/27 01:40:47 christos Exp $ */ 2 /* $OpenBSD: serverloop.c,v 1.159 2009/05/28 16:50:16 andreas 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 1.3 2009/12/27 01:40:47 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 #include "roaming.h" 81 82 extern ServerOptions options; 83 84 /* XXX */ 85 extern Kex *xxx_kex; 86 extern Authctxt *the_authctxt; 87 extern int use_privsep; 88 89 static Buffer stdin_buffer; /* Buffer for stdin data. */ 90 static Buffer stdout_buffer; /* Buffer for stdout data. */ 91 static Buffer stderr_buffer; /* Buffer for stderr data. */ 92 static int fdin; /* Descriptor for stdin (for writing) */ 93 static int fdout; /* Descriptor for stdout (for reading); 94 May be same number as fdin. */ 95 static int fderr; /* Descriptor for stderr. May be -1. */ 96 static u_long stdin_bytes = 0; /* Number of bytes written to stdin. */ 97 static u_long stdout_bytes = 0; /* Number of stdout bytes sent to client. */ 98 static u_long stderr_bytes = 0; /* Number of stderr bytes sent to client. */ 99 static u_long fdout_bytes = 0; /* Number of stdout bytes read from program. */ 100 static int stdin_eof = 0; /* EOF message received from client. */ 101 static int fdout_eof = 0; /* EOF encountered reading from fdout. */ 102 static int fderr_eof = 0; /* EOF encountered readung from fderr. */ 103 static int fdin_is_tty = 0; /* fdin points to a tty. */ 104 static int connection_in; /* Connection to client (input). */ 105 static int connection_out; /* Connection to client (output). */ 106 static int connection_closed = 0; /* Connection to client closed. */ 107 static u_int buffer_high; /* "Soft" max buffer size. */ 108 static int no_more_sessions = 0; /* Disallow further sessions. */ 109 110 /* 111 * This SIGCHLD kludge is used to detect when the child exits. The server 112 * will exit after that, as soon as forwarded connections have terminated. 113 */ 114 115 static volatile sig_atomic_t child_terminated = 0; /* The child has terminated. */ 116 117 /* Cleanup on signals (!use_privsep case only) */ 118 static volatile sig_atomic_t received_sigterm = 0; 119 120 /* prototypes */ 121 static void server_init_dispatch(void); 122 123 /* 124 * Returns current time in seconds from Jan 1, 1970 with the maximum 125 * available resolution. 126 */ 127 128 static double 129 get_current_time(void) 130 { 131 struct timeval tv; 132 gettimeofday(&tv, NULL); 133 return (double) tv.tv_sec + (double) tv.tv_usec / 1000000.0; 134 } 135 136 /* 137 * we write to this pipe if a SIGCHLD is caught in order to avoid 138 * the race between select() and child_terminated 139 */ 140 static int notify_pipe[2]; 141 static void 142 notify_setup(void) 143 { 144 if (pipe(notify_pipe) < 0) { 145 error("pipe(notify_pipe) failed %s", strerror(errno)); 146 } else if ((fcntl(notify_pipe[0], F_SETFD, 1) == -1) || 147 (fcntl(notify_pipe[1], F_SETFD, 1) == -1)) { 148 error("fcntl(notify_pipe, F_SETFD) failed %s", strerror(errno)); 149 close(notify_pipe[0]); 150 close(notify_pipe[1]); 151 } else { 152 set_nonblock(notify_pipe[0]); 153 set_nonblock(notify_pipe[1]); 154 return; 155 } 156 notify_pipe[0] = -1; /* read end */ 157 notify_pipe[1] = -1; /* write end */ 158 } 159 static void 160 notify_parent(void) 161 { 162 if (notify_pipe[1] != -1) 163 write(notify_pipe[1], "", 1); 164 } 165 static void 166 notify_prepare(fd_set *readset) 167 { 168 if (notify_pipe[0] != -1) 169 FD_SET(notify_pipe[0], readset); 170 } 171 static void 172 notify_done(fd_set *readset) 173 { 174 char c; 175 176 if (notify_pipe[0] != -1 && FD_ISSET(notify_pipe[0], readset)) 177 while (read(notify_pipe[0], &c, 1) != -1) 178 debug2("notify_done: reading"); 179 } 180 181 /*ARGSUSED*/ 182 static void 183 sigchld_handler(int sig) 184 { 185 int save_errno = errno; 186 child_terminated = 1; 187 signal(SIGCHLD, sigchld_handler); 188 notify_parent(); 189 errno = save_errno; 190 } 191 192 /*ARGSUSED*/ 193 static void 194 sigterm_handler(int sig) 195 { 196 received_sigterm = sig; 197 } 198 199 /* 200 * Make packets from buffered stderr data, and buffer it for sending 201 * to the client. 202 */ 203 static void 204 make_packets_from_stderr_data(void) 205 { 206 u_int len; 207 208 /* Send buffered stderr data to the client. */ 209 while (buffer_len(&stderr_buffer) > 0 && 210 packet_not_very_much_data_to_write()) { 211 len = buffer_len(&stderr_buffer); 212 if (packet_is_interactive()) { 213 if (len > 512) 214 len = 512; 215 } else { 216 /* Keep the packets at reasonable size. */ 217 if (len > packet_get_maxsize()) 218 len = packet_get_maxsize(); 219 } 220 packet_start(SSH_SMSG_STDERR_DATA); 221 packet_put_string(buffer_ptr(&stderr_buffer), len); 222 packet_send(); 223 buffer_consume(&stderr_buffer, len); 224 stderr_bytes += len; 225 } 226 } 227 228 /* 229 * Make packets from buffered stdout data, and buffer it for sending to the 230 * client. 231 */ 232 static void 233 make_packets_from_stdout_data(void) 234 { 235 u_int len; 236 237 /* Send buffered stdout data to the client. */ 238 while (buffer_len(&stdout_buffer) > 0 && 239 packet_not_very_much_data_to_write()) { 240 len = buffer_len(&stdout_buffer); 241 if (packet_is_interactive()) { 242 if (len > 512) 243 len = 512; 244 } else { 245 /* Keep the packets at reasonable size. */ 246 if (len > packet_get_maxsize()) 247 len = packet_get_maxsize(); 248 } 249 packet_start(SSH_SMSG_STDOUT_DATA); 250 packet_put_string(buffer_ptr(&stdout_buffer), len); 251 packet_send(); 252 buffer_consume(&stdout_buffer, len); 253 stdout_bytes += len; 254 } 255 } 256 257 static void 258 client_alive_check(void) 259 { 260 int channel_id; 261 262 /* timeout, check to see how many we have had */ 263 if (packet_inc_alive_timeouts() > options.client_alive_count_max) { 264 logit("Timeout, client not responding."); 265 cleanup_exit(255); 266 } 267 268 /* 269 * send a bogus global/channel request with "wantreply", 270 * we should get back a failure 271 */ 272 if ((channel_id = channel_find_open()) == -1) { 273 packet_start(SSH2_MSG_GLOBAL_REQUEST); 274 packet_put_cstring("keepalive@openssh.com"); 275 packet_put_char(1); /* boolean: want reply */ 276 } else { 277 channel_request_start(channel_id, "keepalive@openssh.com", 1); 278 } 279 packet_send(); 280 } 281 282 /* 283 * Sleep in select() until we can do something. This will initialize the 284 * select masks. Upon return, the masks will indicate which descriptors 285 * have data or can accept data. Optionally, a maximum time can be specified 286 * for the duration of the wait (0 = infinite). 287 */ 288 static void 289 wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp, 290 u_int *nallocp, u_int max_time_milliseconds) 291 { 292 struct timeval tv, *tvp; 293 int ret; 294 int client_alive_scheduled = 0; 295 296 /* 297 * if using client_alive, set the max timeout accordingly, 298 * and indicate that this particular timeout was for client 299 * alive by setting the client_alive_scheduled flag. 300 * 301 * this could be randomized somewhat to make traffic 302 * analysis more difficult, but we're not doing it yet. 303 */ 304 if (compat20 && 305 max_time_milliseconds == 0 && options.client_alive_interval) { 306 client_alive_scheduled = 1; 307 max_time_milliseconds = options.client_alive_interval * 1000; 308 } 309 310 /* Allocate and update select() masks for channel descriptors. */ 311 channel_prepare_select(readsetp, writesetp, maxfdp, nallocp, 0); 312 313 if (compat20) { 314 #if 0 315 /* wrong: bad condition XXX */ 316 if (channel_not_very_much_buffered_data()) 317 #endif 318 FD_SET(connection_in, *readsetp); 319 } else { 320 /* 321 * Read packets from the client unless we have too much 322 * buffered stdin or channel data. 323 */ 324 if (buffer_len(&stdin_buffer) < buffer_high && 325 channel_not_very_much_buffered_data()) 326 FD_SET(connection_in, *readsetp); 327 /* 328 * If there is not too much data already buffered going to 329 * the client, try to get some more data from the program. 330 */ 331 if (packet_not_very_much_data_to_write()) { 332 if (!fdout_eof) 333 FD_SET(fdout, *readsetp); 334 if (!fderr_eof) 335 FD_SET(fderr, *readsetp); 336 } 337 /* 338 * If we have buffered data, try to write some of that data 339 * to the program. 340 */ 341 if (fdin != -1 && buffer_len(&stdin_buffer) > 0) 342 FD_SET(fdin, *writesetp); 343 } 344 notify_prepare(*readsetp); 345 346 /* 347 * If we have buffered packet data going to the client, mark that 348 * descriptor. 349 */ 350 if (packet_have_data_to_write()) 351 FD_SET(connection_out, *writesetp); 352 353 /* 354 * If child has terminated and there is enough buffer space to read 355 * from it, then read as much as is available and exit. 356 */ 357 if (child_terminated && packet_not_very_much_data_to_write()) 358 if (max_time_milliseconds == 0 || client_alive_scheduled) 359 max_time_milliseconds = 100; 360 361 if (max_time_milliseconds == 0) 362 tvp = NULL; 363 else { 364 tv.tv_sec = max_time_milliseconds / 1000; 365 tv.tv_usec = 1000 * (max_time_milliseconds % 1000); 366 tvp = &tv; 367 } 368 369 /* Wait for something to happen, or the timeout to expire. */ 370 ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp); 371 372 if (ret == -1) { 373 memset(*readsetp, 0, *nallocp); 374 memset(*writesetp, 0, *nallocp); 375 if (errno != EINTR) 376 error("select: %.100s", strerror(errno)); 377 } else if (ret == 0 && client_alive_scheduled) 378 client_alive_check(); 379 380 notify_done(*readsetp); 381 } 382 383 /* 384 * Processes input from the client and the program. Input data is stored 385 * in buffers and processed later. 386 */ 387 static void 388 process_input(fd_set *readset) 389 { 390 int len; 391 char buf[16384]; 392 393 /* Read and buffer any input data from the client. */ 394 if (FD_ISSET(connection_in, readset)) { 395 int cont = 0; 396 len = roaming_read(connection_in, buf, sizeof(buf), &cont); 397 if (len == 0) { 398 if (cont) 399 return; 400 verbose("Connection closed by %.100s", 401 get_remote_ipaddr()); 402 connection_closed = 1; 403 if (compat20) 404 return; 405 cleanup_exit(255); 406 } else if (len < 0) { 407 if (errno != EINTR && errno != EAGAIN) { 408 verbose("Read error from remote host " 409 "%.100s: %.100s", 410 get_remote_ipaddr(), strerror(errno)); 411 cleanup_exit(255); 412 } 413 } else { 414 /* Buffer any received data. */ 415 packet_process_incoming(buf, len); 416 fdout_bytes += len; 417 } 418 } 419 if (compat20) 420 return; 421 422 /* Read and buffer any available stdout data from the program. */ 423 if (!fdout_eof && FD_ISSET(fdout, readset)) { 424 len = read(fdout, buf, sizeof(buf)); 425 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 426 /* do nothing */ 427 } else if (len <= 0) { 428 fdout_eof = 1; 429 } else { 430 buffer_append(&stdout_buffer, buf, len); 431 debug ("FD out now: %ld", fdout_bytes); 432 fdout_bytes += len; 433 } 434 } 435 /* Read and buffer any available stderr data from the program. */ 436 if (!fderr_eof && FD_ISSET(fderr, readset)) { 437 len = read(fderr, buf, sizeof(buf)); 438 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 439 /* do nothing */ 440 } else if (len <= 0) { 441 fderr_eof = 1; 442 } else { 443 buffer_append(&stderr_buffer, buf, len); 444 } 445 } 446 } 447 448 /* 449 * Sends data from internal buffers to client program stdin. 450 */ 451 static void 452 process_output(fd_set *writeset) 453 { 454 struct termios tio; 455 u_char *data; 456 u_int dlen; 457 int len; 458 459 /* Write buffered data to program stdin. */ 460 if (!compat20 && fdin != -1 && FD_ISSET(fdin, writeset)) { 461 data = buffer_ptr(&stdin_buffer); 462 dlen = buffer_len(&stdin_buffer); 463 len = write(fdin, data, dlen); 464 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 465 /* do nothing */ 466 } else if (len <= 0) { 467 if (fdin != fdout) 468 close(fdin); 469 else 470 shutdown(fdin, SHUT_WR); /* We will no longer send. */ 471 fdin = -1; 472 } else { 473 /* Successful write. */ 474 if (fdin_is_tty && dlen >= 1 && data[0] != '\r' && 475 tcgetattr(fdin, &tio) == 0 && 476 !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) { 477 /* 478 * Simulate echo to reduce the impact of 479 * traffic analysis 480 */ 481 packet_send_ignore(len); 482 packet_send(); 483 } 484 /* Consume the data from the buffer. */ 485 buffer_consume(&stdin_buffer, len); 486 /* Update the count of bytes written to the program. */ 487 stdin_bytes += len; 488 } 489 } 490 /* Send any buffered packet data to the client. */ 491 if (FD_ISSET(connection_out, writeset)) 492 stdin_bytes += packet_write_poll(); 493 } 494 495 /* 496 * Wait until all buffered output has been sent to the client. 497 * This is used when the program terminates. 498 */ 499 static void 500 drain_output(void) 501 { 502 /* Send any buffered stdout data to the client. */ 503 if (buffer_len(&stdout_buffer) > 0) { 504 packet_start(SSH_SMSG_STDOUT_DATA); 505 packet_put_string(buffer_ptr(&stdout_buffer), 506 buffer_len(&stdout_buffer)); 507 packet_send(); 508 /* Update the count of sent bytes. */ 509 stdout_bytes += buffer_len(&stdout_buffer); 510 } 511 /* Send any buffered stderr data to the client. */ 512 if (buffer_len(&stderr_buffer) > 0) { 513 packet_start(SSH_SMSG_STDERR_DATA); 514 packet_put_string(buffer_ptr(&stderr_buffer), 515 buffer_len(&stderr_buffer)); 516 packet_send(); 517 /* Update the count of sent bytes. */ 518 stderr_bytes += buffer_len(&stderr_buffer); 519 } 520 /* Wait until all buffered data has been written to the client. */ 521 packet_write_wait(); 522 } 523 524 static void 525 process_buffered_input_packets(void) 526 { 527 dispatch_run(DISPATCH_NONBLOCK, NULL, compat20 ? xxx_kex : NULL); 528 } 529 530 /* 531 * Performs the interactive session. This handles data transmission between 532 * the client and the program. Note that the notion of stdin, stdout, and 533 * stderr in this function is sort of reversed: this function writes to 534 * stdin (of the child program), and reads from stdout and stderr (of the 535 * child program). 536 */ 537 void 538 server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg) 539 { 540 fd_set *readset = NULL, *writeset = NULL; 541 int max_fd = 0; 542 u_int nalloc = 0; 543 int wait_status; /* Status returned by wait(). */ 544 pid_t wait_pid; /* pid returned by wait(). */ 545 int waiting_termination = 0; /* Have displayed waiting close message. */ 546 u_int max_time_milliseconds; 547 u_int previous_stdout_buffer_bytes; 548 u_int stdout_buffer_bytes; 549 int type; 550 551 debug("Entering interactive session."); 552 553 /* Initialize the SIGCHLD kludge. */ 554 child_terminated = 0; 555 signal(SIGCHLD, sigchld_handler); 556 557 if (!use_privsep) { 558 signal(SIGTERM, sigterm_handler); 559 signal(SIGINT, sigterm_handler); 560 signal(SIGQUIT, sigterm_handler); 561 } 562 563 /* Initialize our global variables. */ 564 fdin = fdin_arg; 565 fdout = fdout_arg; 566 fderr = fderr_arg; 567 568 /* nonblocking IO */ 569 set_nonblock(fdin); 570 set_nonblock(fdout); 571 /* we don't have stderr for interactive terminal sessions, see below */ 572 if (fderr != -1) 573 set_nonblock(fderr); 574 575 if (!(datafellows & SSH_BUG_IGNOREMSG) && isatty(fdin)) 576 fdin_is_tty = 1; 577 578 connection_in = packet_get_connection_in(); 579 connection_out = packet_get_connection_out(); 580 581 notify_setup(); 582 583 previous_stdout_buffer_bytes = 0; 584 585 /* Set approximate I/O buffer size. */ 586 if (packet_is_interactive()) 587 buffer_high = 4096; 588 else 589 buffer_high = 64 * 1024; 590 591 #if 0 592 /* Initialize max_fd to the maximum of the known file descriptors. */ 593 max_fd = MAX(connection_in, connection_out); 594 max_fd = MAX(max_fd, fdin); 595 max_fd = MAX(max_fd, fdout); 596 if (fderr != -1) 597 max_fd = MAX(max_fd, fderr); 598 #endif 599 600 /* Initialize Initialize buffers. */ 601 buffer_init(&stdin_buffer); 602 buffer_init(&stdout_buffer); 603 buffer_init(&stderr_buffer); 604 605 /* 606 * If we have no separate fderr (which is the case when we have a pty 607 * - there we cannot make difference between data sent to stdout and 608 * stderr), indicate that we have seen an EOF from stderr. This way 609 * we don't need to check the descriptor everywhere. 610 */ 611 if (fderr == -1) 612 fderr_eof = 1; 613 614 server_init_dispatch(); 615 616 /* Main loop of the server for the interactive session mode. */ 617 for (;;) { 618 619 /* Process buffered packets from the client. */ 620 process_buffered_input_packets(); 621 622 /* 623 * If we have received eof, and there is no more pending 624 * input data, cause a real eof by closing fdin. 625 */ 626 if (stdin_eof && fdin != -1 && buffer_len(&stdin_buffer) == 0) { 627 if (fdin != fdout) 628 close(fdin); 629 else 630 shutdown(fdin, SHUT_WR); /* We will no longer send. */ 631 fdin = -1; 632 } 633 /* Make packets from buffered stderr data to send to the client. */ 634 make_packets_from_stderr_data(); 635 636 /* 637 * Make packets from buffered stdout data to send to the 638 * client. If there is very little to send, this arranges to 639 * not send them now, but to wait a short while to see if we 640 * are getting more data. This is necessary, as some systems 641 * wake up readers from a pty after each separate character. 642 */ 643 max_time_milliseconds = 0; 644 stdout_buffer_bytes = buffer_len(&stdout_buffer); 645 if (stdout_buffer_bytes != 0 && stdout_buffer_bytes < 256 && 646 stdout_buffer_bytes != previous_stdout_buffer_bytes) { 647 /* try again after a while */ 648 max_time_milliseconds = 10; 649 } else { 650 /* Send it now. */ 651 make_packets_from_stdout_data(); 652 } 653 previous_stdout_buffer_bytes = buffer_len(&stdout_buffer); 654 655 /* Send channel data to the client. */ 656 if (packet_not_very_much_data_to_write()) 657 channel_output_poll(); 658 659 /* 660 * Bail out of the loop if the program has closed its output 661 * descriptors, and we have no more data to send to the 662 * client, and there is no pending buffered data. 663 */ 664 if (fdout_eof && fderr_eof && !packet_have_data_to_write() && 665 buffer_len(&stdout_buffer) == 0 && buffer_len(&stderr_buffer) == 0) { 666 if (!channel_still_open()) 667 break; 668 if (!waiting_termination) { 669 const char *s = "Waiting for forwarded connections to terminate...\r\n"; 670 char *cp; 671 waiting_termination = 1; 672 buffer_append(&stderr_buffer, s, strlen(s)); 673 674 /* Display list of open channels. */ 675 cp = channel_open_message(); 676 buffer_append(&stderr_buffer, cp, strlen(cp)); 677 xfree(cp); 678 } 679 } 680 max_fd = MAX(connection_in, connection_out); 681 max_fd = MAX(max_fd, fdin); 682 max_fd = MAX(max_fd, fdout); 683 max_fd = MAX(max_fd, fderr); 684 max_fd = MAX(max_fd, notify_pipe[0]); 685 686 /* Sleep in select() until we can do something. */ 687 wait_until_can_do_something(&readset, &writeset, &max_fd, 688 &nalloc, max_time_milliseconds); 689 690 if (received_sigterm) { 691 logit("Exiting on signal %ld", (long)received_sigterm); 692 /* Clean up sessions, utmp, etc. */ 693 cleanup_exit(255); 694 } 695 696 /* Process any channel events. */ 697 channel_after_select(readset, writeset); 698 699 /* Process input from the client and from program stdout/stderr. */ 700 process_input(readset); 701 702 /* Process output to the client and to program stdin. */ 703 process_output(writeset); 704 } 705 if (readset) 706 xfree(readset); 707 if (writeset) 708 xfree(writeset); 709 710 /* Cleanup and termination code. */ 711 712 /* Wait until all output has been sent to the client. */ 713 drain_output(); 714 715 debug("End of interactive session; stdin %ld, stdout (read %ld, sent %ld), stderr %ld bytes.", 716 stdin_bytes, fdout_bytes, stdout_bytes, stderr_bytes); 717 718 /* Free and clear the buffers. */ 719 buffer_free(&stdin_buffer); 720 buffer_free(&stdout_buffer); 721 buffer_free(&stderr_buffer); 722 723 /* Close the file descriptors. */ 724 if (fdout != -1) 725 close(fdout); 726 fdout = -1; 727 fdout_eof = 1; 728 if (fderr != -1) 729 close(fderr); 730 fderr = -1; 731 fderr_eof = 1; 732 if (fdin != -1) 733 close(fdin); 734 fdin = -1; 735 736 channel_free_all(); 737 738 /* We no longer want our SIGCHLD handler to be called. */ 739 signal(SIGCHLD, SIG_DFL); 740 741 while ((wait_pid = waitpid(-1, &wait_status, 0)) < 0) 742 if (errno != EINTR) 743 packet_disconnect("wait: %.100s", strerror(errno)); 744 if (wait_pid != pid) 745 error("Strange, wait returned pid %ld, expected %ld", 746 (long)wait_pid, (long)pid); 747 748 /* Check if it exited normally. */ 749 if (WIFEXITED(wait_status)) { 750 /* Yes, normal exit. Get exit status and send it to the client. */ 751 debug("Command exited with status %d.", WEXITSTATUS(wait_status)); 752 packet_start(SSH_SMSG_EXITSTATUS); 753 packet_put_int(WEXITSTATUS(wait_status)); 754 packet_send(); 755 packet_write_wait(); 756 757 /* 758 * Wait for exit confirmation. Note that there might be 759 * other packets coming before it; however, the program has 760 * already died so we just ignore them. The client is 761 * supposed to respond with the confirmation when it receives 762 * the exit status. 763 */ 764 do { 765 type = packet_read(); 766 } 767 while (type != SSH_CMSG_EXIT_CONFIRMATION); 768 769 debug("Received exit confirmation."); 770 return; 771 } 772 /* Check if the program terminated due to a signal. */ 773 if (WIFSIGNALED(wait_status)) 774 packet_disconnect("Command terminated on signal %d.", 775 WTERMSIG(wait_status)); 776 777 /* Some weird exit cause. Just exit. */ 778 packet_disconnect("wait returned status %04x.", wait_status); 779 /* NOTREACHED */ 780 } 781 782 static void 783 collect_children(void) 784 { 785 pid_t pid; 786 sigset_t oset, nset; 787 int status; 788 789 /* block SIGCHLD while we check for dead children */ 790 sigemptyset(&nset); 791 sigaddset(&nset, SIGCHLD); 792 sigprocmask(SIG_BLOCK, &nset, &oset); 793 if (child_terminated) { 794 debug("Received SIGCHLD."); 795 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 796 (pid < 0 && errno == EINTR)) 797 if (pid > 0) 798 session_close_by_pid(pid, status); 799 child_terminated = 0; 800 } 801 sigprocmask(SIG_SETMASK, &oset, NULL); 802 } 803 804 void 805 server_loop2(Authctxt *authctxt) 806 { 807 fd_set *readset = NULL, *writeset = NULL; 808 int rekeying = 0, max_fd; 809 u_int nalloc = 0; 810 double start_time, total_time; 811 812 debug("Entering interactive session for SSH2."); 813 start_time = get_current_time(); 814 815 signal(SIGCHLD, sigchld_handler); 816 child_terminated = 0; 817 connection_in = packet_get_connection_in(); 818 connection_out = packet_get_connection_out(); 819 820 if (!use_privsep) { 821 signal(SIGTERM, sigterm_handler); 822 signal(SIGINT, sigterm_handler); 823 signal(SIGQUIT, sigterm_handler); 824 } 825 826 notify_setup(); 827 828 max_fd = MAX(connection_in, connection_out); 829 max_fd = MAX(max_fd, notify_pipe[0]); 830 831 server_init_dispatch(); 832 833 for (;;) { 834 process_buffered_input_packets(); 835 836 rekeying = (xxx_kex != NULL && !xxx_kex->done); 837 838 if (!rekeying && packet_not_very_much_data_to_write()) 839 channel_output_poll(); 840 wait_until_can_do_something(&readset, &writeset, &max_fd, 841 &nalloc, 0); 842 843 if (received_sigterm) { 844 logit("Exiting on signal %ld", (long)received_sigterm); 845 /* Clean up sessions, utmp, etc. */ 846 cleanup_exit(255); 847 } 848 849 collect_children(); 850 if (!rekeying) { 851 channel_after_select(readset, writeset); 852 if (packet_need_rekeying()) { 853 debug("need rekeying"); 854 xxx_kex->done = 0; 855 kex_send_kexinit(xxx_kex); 856 } 857 } 858 process_input(readset); 859 if (connection_closed) 860 break; 861 process_output(writeset); 862 } 863 collect_children(); 864 865 if (readset) 866 xfree(readset); 867 if (writeset) 868 xfree(writeset); 869 870 /* free all channels, no more reads and writes */ 871 channel_free_all(); 872 873 /* free remaining sessions, e.g. remove wtmp entries */ 874 session_destroy_all(NULL); 875 total_time = get_current_time() - start_time; 876 logit("SSH: Server;LType: Throughput;Remote: %s-%d;IN: %lu;OUT: %lu;Duration: %.1f;tPut_in: %.1f;tPut_out: %.1f", 877 get_remote_ipaddr(), get_remote_port(), 878 stdin_bytes, fdout_bytes, total_time, stdin_bytes / total_time, 879 fdout_bytes / total_time); 880 } 881 882 static void 883 server_input_keep_alive(int type, u_int32_t seq, void *ctxt) 884 { 885 debug("Got %d/%u for keepalive", type, seq); 886 /* 887 * reset timeout, since we got a sane answer from the client. 888 * even if this was generated by something other than 889 * the bogus CHANNEL_REQUEST we send for keepalives. 890 */ 891 packet_set_alive_timeouts(0); 892 } 893 894 static void 895 server_input_stdin_data(int type, u_int32_t seq, void *ctxt) 896 { 897 char *data; 898 u_int data_len; 899 900 /* Stdin data from the client. Append it to the buffer. */ 901 /* Ignore any data if the client has closed stdin. */ 902 if (fdin == -1) 903 return; 904 data = packet_get_string(&data_len); 905 packet_check_eom(); 906 buffer_append(&stdin_buffer, data, data_len); 907 memset(data, 0, data_len); 908 xfree(data); 909 } 910 911 static void 912 server_input_eof(int type, u_int32_t seq, void *ctxt) 913 { 914 /* 915 * Eof from the client. The stdin descriptor to the 916 * program will be closed when all buffered data has 917 * drained. 918 */ 919 debug("EOF received for stdin."); 920 packet_check_eom(); 921 stdin_eof = 1; 922 } 923 924 static void 925 server_input_window_size(int type, u_int32_t seq, void *ctxt) 926 { 927 u_int row = packet_get_int(); 928 u_int col = packet_get_int(); 929 u_int xpixel = packet_get_int(); 930 u_int ypixel = packet_get_int(); 931 932 debug("Window change received."); 933 packet_check_eom(); 934 if (fdin != -1) 935 pty_change_window_size(fdin, row, col, xpixel, ypixel); 936 } 937 938 static Channel * 939 server_request_direct_tcpip(void) 940 { 941 Channel *c; 942 char *target, *originator; 943 u_short target_port, originator_port; 944 945 target = packet_get_string(NULL); 946 target_port = packet_get_int(); 947 originator = packet_get_string(NULL); 948 originator_port = packet_get_int(); 949 packet_check_eom(); 950 951 debug("server_request_direct_tcpip: originator %s port %d, target %s " 952 "port %d", originator, originator_port, target, target_port); 953 954 /* XXX check permission */ 955 c = channel_connect_to(target, target_port, 956 "direct-tcpip", "direct-tcpip"); 957 958 xfree(originator); 959 xfree(target); 960 961 return c; 962 } 963 964 static Channel * 965 server_request_tun(void) 966 { 967 Channel *c = NULL; 968 int mode, tun; 969 int sock; 970 971 mode = packet_get_int(); 972 switch (mode) { 973 case SSH_TUNMODE_POINTOPOINT: 974 case SSH_TUNMODE_ETHERNET: 975 break; 976 default: 977 packet_send_debug("Unsupported tunnel device mode."); 978 return NULL; 979 } 980 if ((options.permit_tun & mode) == 0) { 981 packet_send_debug("Server has rejected tunnel device " 982 "forwarding"); 983 return NULL; 984 } 985 986 tun = packet_get_int(); 987 if (forced_tun_device != -1) { 988 if (tun != SSH_TUNID_ANY && forced_tun_device != tun) 989 goto done; 990 tun = forced_tun_device; 991 } 992 sock = tun_open(tun, mode); 993 if (sock < 0) 994 goto done; 995 if (options.hpn_disabled) 996 c = channel_new("tun", SSH_CHANNEL_OPEN, sock, sock, -1, 997 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1); 998 else 999 c = channel_new("tun", SSH_CHANNEL_OPEN, sock, sock, -1, 1000 options.hpn_buffer_size, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1); 1001 c->datagram = 1; 1002 1003 done: 1004 if (c == NULL) 1005 packet_send_debug("Failed to open the tunnel device."); 1006 return c; 1007 } 1008 1009 static Channel * 1010 server_request_session(void) 1011 { 1012 Channel *c; 1013 1014 debug("input_session_request"); 1015 packet_check_eom(); 1016 1017 if (no_more_sessions) { 1018 packet_disconnect("Possible attack: attempt to open a session " 1019 "after additional sessions disabled"); 1020 } 1021 1022 /* 1023 * A server session has no fd to read or write until a 1024 * CHANNEL_REQUEST for a shell is made, so we set the type to 1025 * SSH_CHANNEL_LARVAL. Additionally, a callback for handling all 1026 * CHANNEL_REQUEST messages is registered. 1027 */ 1028 c = channel_new("session", SSH_CHANNEL_LARVAL, 1029 -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT, 1030 0, "server-session", 1); 1031 if ((options.tcp_rcv_buf_poll > 0) && (!options.hpn_disabled)) 1032 c->dynamic_window = 1; 1033 if (session_open(the_authctxt, c->self) != 1) { 1034 debug("session open failed, free channel %d", c->self); 1035 channel_free(c); 1036 return NULL; 1037 } 1038 channel_register_cleanup(c->self, session_close_by_channel, 0); 1039 return c; 1040 } 1041 1042 static void 1043 server_input_channel_open(int type, u_int32_t seq, void *ctxt) 1044 { 1045 Channel *c = NULL; 1046 char *ctype; 1047 int rchan; 1048 u_int rmaxpack, rwindow, len; 1049 1050 ctype = packet_get_string(&len); 1051 rchan = packet_get_int(); 1052 rwindow = packet_get_int(); 1053 rmaxpack = packet_get_int(); 1054 1055 debug("server_input_channel_open: ctype %s rchan %d win %d max %d", 1056 ctype, rchan, rwindow, rmaxpack); 1057 1058 if (strcmp(ctype, "session") == 0) { 1059 c = server_request_session(); 1060 } else if (strcmp(ctype, "direct-tcpip") == 0) { 1061 c = server_request_direct_tcpip(); 1062 } else if (strcmp(ctype, "tun@openssh.com") == 0) { 1063 c = server_request_tun(); 1064 } 1065 if (c != NULL) { 1066 debug("server_input_channel_open: confirm %s", ctype); 1067 c->remote_id = rchan; 1068 c->remote_window = rwindow; 1069 c->remote_maxpacket = rmaxpack; 1070 if (c->type != SSH_CHANNEL_CONNECTING) { 1071 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION); 1072 packet_put_int(c->remote_id); 1073 packet_put_int(c->self); 1074 packet_put_int(c->local_window); 1075 packet_put_int(c->local_maxpacket); 1076 packet_send(); 1077 } 1078 } else { 1079 debug("server_input_channel_open: failure %s", ctype); 1080 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE); 1081 packet_put_int(rchan); 1082 packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED); 1083 if (!(datafellows & SSH_BUG_OPENFAILURE)) { 1084 packet_put_cstring("open failed"); 1085 packet_put_cstring(""); 1086 } 1087 packet_send(); 1088 } 1089 xfree(ctype); 1090 } 1091 1092 static void 1093 server_input_global_request(int type, u_int32_t seq, void *ctxt) 1094 { 1095 char *rtype; 1096 int want_reply; 1097 int success = 0, allocated_listen_port = 0; 1098 1099 rtype = packet_get_string(NULL); 1100 want_reply = packet_get_char(); 1101 debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply); 1102 1103 /* -R style forwarding */ 1104 if (strcmp(rtype, "tcpip-forward") == 0) { 1105 struct passwd *pw; 1106 char *listen_address; 1107 u_short listen_port; 1108 1109 pw = the_authctxt->pw; 1110 if (pw == NULL || !the_authctxt->valid) 1111 fatal("server_input_global_request: no/invalid user"); 1112 listen_address = packet_get_string(NULL); 1113 listen_port = (u_short)packet_get_int(); 1114 debug("server_input_global_request: tcpip-forward listen %s port %d", 1115 listen_address, listen_port); 1116 1117 /* check permissions */ 1118 if (!options.allow_tcp_forwarding || 1119 no_port_forwarding_flag || 1120 (!want_reply && listen_port == 0) || 1121 (listen_port != 0 && listen_port < IPPORT_RESERVED && 1122 pw->pw_uid != 0)) { 1123 success = 0; 1124 packet_send_debug("Server has disabled port forwarding."); 1125 } else { 1126 /* Start listening on the port */ 1127 success = channel_setup_remote_fwd_listener( 1128 listen_address, listen_port, 1129 &allocated_listen_port, options.gateway_ports); 1130 } 1131 xfree(listen_address); 1132 } else if (strcmp(rtype, "cancel-tcpip-forward") == 0) { 1133 char *cancel_address; 1134 u_short cancel_port; 1135 1136 cancel_address = packet_get_string(NULL); 1137 cancel_port = (u_short)packet_get_int(); 1138 debug("%s: cancel-tcpip-forward addr %s port %d", __func__, 1139 cancel_address, cancel_port); 1140 1141 success = channel_cancel_rport_listener(cancel_address, 1142 cancel_port); 1143 xfree(cancel_address); 1144 } else if (strcmp(rtype, "no-more-sessions@openssh.com") == 0) { 1145 no_more_sessions = 1; 1146 success = 1; 1147 } 1148 if (want_reply) { 1149 packet_start(success ? 1150 SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE); 1151 if (success && allocated_listen_port > 0) 1152 packet_put_int(allocated_listen_port); 1153 packet_send(); 1154 packet_write_wait(); 1155 } 1156 xfree(rtype); 1157 } 1158 1159 static void 1160 server_input_channel_req(int type, u_int32_t seq, void *ctxt) 1161 { 1162 Channel *c; 1163 int id, reply, success = 0; 1164 char *rtype; 1165 1166 id = packet_get_int(); 1167 rtype = packet_get_string(NULL); 1168 reply = packet_get_char(); 1169 1170 debug("server_input_channel_req: channel %d request %s reply %d", 1171 id, rtype, reply); 1172 1173 if ((c = channel_lookup(id)) == NULL) 1174 packet_disconnect("server_input_channel_req: " 1175 "unknown channel %d", id); 1176 if (!strcmp(rtype, "eow@openssh.com")) { 1177 packet_check_eom(); 1178 chan_rcvd_eow(c); 1179 } else if ((c->type == SSH_CHANNEL_LARVAL || 1180 c->type == SSH_CHANNEL_OPEN) && strcmp(c->ctype, "session") == 0) 1181 success = session_input_channel_req(c, rtype); 1182 if (reply) { 1183 packet_start(success ? 1184 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE); 1185 packet_put_int(c->remote_id); 1186 packet_send(); 1187 } 1188 xfree(rtype); 1189 } 1190 1191 static void 1192 server_init_dispatch_20(void) 1193 { 1194 debug("server_init_dispatch_20"); 1195 dispatch_init(&dispatch_protocol_error); 1196 dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); 1197 dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data); 1198 dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); 1199 dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); 1200 dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open); 1201 dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 1202 dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 1203 dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req); 1204 dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); 1205 dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request); 1206 /* client_alive */ 1207 dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &server_input_keep_alive); 1208 dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_keep_alive); 1209 dispatch_set(SSH2_MSG_REQUEST_SUCCESS, &server_input_keep_alive); 1210 dispatch_set(SSH2_MSG_REQUEST_FAILURE, &server_input_keep_alive); 1211 /* rekeying */ 1212 dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); 1213 } 1214 static void 1215 server_init_dispatch_13(void) 1216 { 1217 debug("server_init_dispatch_13"); 1218 dispatch_init(NULL); 1219 dispatch_set(SSH_CMSG_EOF, &server_input_eof); 1220 dispatch_set(SSH_CMSG_STDIN_DATA, &server_input_stdin_data); 1221 dispatch_set(SSH_CMSG_WINDOW_SIZE, &server_input_window_size); 1222 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close); 1223 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation); 1224 dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data); 1225 dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 1226 dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 1227 dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open); 1228 } 1229 static void 1230 server_init_dispatch_15(void) 1231 { 1232 server_init_dispatch_13(); 1233 debug("server_init_dispatch_15"); 1234 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof); 1235 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_oclose); 1236 } 1237 static void 1238 server_init_dispatch(void) 1239 { 1240 if (compat20) 1241 server_init_dispatch_20(); 1242 else if (compat13) 1243 server_init_dispatch_13(); 1244 else 1245 server_init_dispatch_15(); 1246 } 1247