1 /* 2 * Author: Tatu Ylonen <ylo@cs.hut.fi> 3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 4 * All rights reserved 5 * Server main loop for handling the interactive session. 6 * 7 * As far as I am concerned, the code I have written for this software 8 * can be used freely for any purpose. Any derived versions of this 9 * software must be clearly marked as such, and if the derived work is 10 * incompatible with the protocol description in the RFC file, it must be 11 * called by a name other than "ssh" or "Secure Shell". 12 * 13 * SSH2 support by Markus Friedl. 14 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 15 * 16 * Redistribution and use in source and binary forms, with or without 17 * modification, are permitted provided that the following conditions 18 * are met: 19 * 1. Redistributions of source code must retain the above copyright 20 * notice, this list of conditions and the following disclaimer. 21 * 2. Redistributions in binary form must reproduce the above copyright 22 * notice, this list of conditions and the following disclaimer in the 23 * documentation and/or other materials provided with the distribution. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 26 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 27 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 28 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 29 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 30 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 31 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 32 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 33 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 34 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 35 */ 36 37 #include "includes.h" 38 RCSID("$OpenBSD: serverloop.c,v 1.115 2004/01/19 21:25:15 markus Exp $"); 39 40 #include "xmalloc.h" 41 #include "packet.h" 42 #include "buffer.h" 43 #include "log.h" 44 #include "servconf.h" 45 #include "canohost.h" 46 #include "sshpty.h" 47 #include "channels.h" 48 #include "compat.h" 49 #include "ssh1.h" 50 #include "ssh2.h" 51 #include "auth.h" 52 #include "session.h" 53 #include "dispatch.h" 54 #include "auth-options.h" 55 #include "serverloop.h" 56 #include "misc.h" 57 #include "kex.h" 58 59 extern ServerOptions options; 60 61 /* XXX */ 62 extern Kex *xxx_kex; 63 extern Authctxt *the_authctxt; 64 65 static Buffer stdin_buffer; /* Buffer for stdin data. */ 66 static Buffer stdout_buffer; /* Buffer for stdout data. */ 67 static Buffer stderr_buffer; /* Buffer for stderr data. */ 68 static int fdin; /* Descriptor for stdin (for writing) */ 69 static int fdout; /* Descriptor for stdout (for reading); 70 May be same number as fdin. */ 71 static int fderr; /* Descriptor for stderr. May be -1. */ 72 static long stdin_bytes = 0; /* Number of bytes written to stdin. */ 73 static long stdout_bytes = 0; /* Number of stdout bytes sent to client. */ 74 static long stderr_bytes = 0; /* Number of stderr bytes sent to client. */ 75 static long fdout_bytes = 0; /* Number of stdout bytes read from program. */ 76 static int stdin_eof = 0; /* EOF message received from client. */ 77 static int fdout_eof = 0; /* EOF encountered reading from fdout. */ 78 static int fderr_eof = 0; /* EOF encountered readung from fderr. */ 79 static int fdin_is_tty = 0; /* fdin points to a tty. */ 80 static int connection_in; /* Connection to client (input). */ 81 static int connection_out; /* Connection to client (output). */ 82 static int connection_closed = 0; /* Connection to client closed. */ 83 static u_int buffer_high; /* "Soft" max buffer size. */ 84 static int client_alive_timeouts = 0; 85 86 /* 87 * This SIGCHLD kludge is used to detect when the child exits. The server 88 * will exit after that, as soon as forwarded connections have terminated. 89 */ 90 91 static volatile sig_atomic_t child_terminated = 0; /* The child has terminated. */ 92 93 /* prototypes */ 94 static void server_init_dispatch(void); 95 96 /* 97 * we write to this pipe if a SIGCHLD is caught in order to avoid 98 * the race between select() and child_terminated 99 */ 100 static int notify_pipe[2]; 101 static void 102 notify_setup(void) 103 { 104 if (pipe(notify_pipe) < 0) { 105 error("pipe(notify_pipe) failed %s", strerror(errno)); 106 } else if ((fcntl(notify_pipe[0], F_SETFD, 1) == -1) || 107 (fcntl(notify_pipe[1], F_SETFD, 1) == -1)) { 108 error("fcntl(notify_pipe, F_SETFD) failed %s", strerror(errno)); 109 close(notify_pipe[0]); 110 close(notify_pipe[1]); 111 } else { 112 set_nonblock(notify_pipe[0]); 113 set_nonblock(notify_pipe[1]); 114 return; 115 } 116 notify_pipe[0] = -1; /* read end */ 117 notify_pipe[1] = -1; /* write end */ 118 } 119 static void 120 notify_parent(void) 121 { 122 if (notify_pipe[1] != -1) 123 write(notify_pipe[1], "", 1); 124 } 125 static void 126 notify_prepare(fd_set *readset) 127 { 128 if (notify_pipe[0] != -1) 129 FD_SET(notify_pipe[0], readset); 130 } 131 static void 132 notify_done(fd_set *readset) 133 { 134 char c; 135 136 if (notify_pipe[0] != -1 && FD_ISSET(notify_pipe[0], readset)) 137 while (read(notify_pipe[0], &c, 1) != -1) 138 debug2("notify_done: reading"); 139 } 140 141 static void 142 sigchld_handler(int sig) 143 { 144 int save_errno = errno; 145 debug("Received SIGCHLD."); 146 child_terminated = 1; 147 #ifndef _UNICOS 148 mysignal(SIGCHLD, sigchld_handler); 149 #endif 150 notify_parent(); 151 errno = save_errno; 152 } 153 154 /* 155 * Make packets from buffered stderr data, and buffer it for sending 156 * to the client. 157 */ 158 static void 159 make_packets_from_stderr_data(void) 160 { 161 u_int len; 162 163 /* Send buffered stderr data to the client. */ 164 while (buffer_len(&stderr_buffer) > 0 && 165 packet_not_very_much_data_to_write()) { 166 len = buffer_len(&stderr_buffer); 167 if (packet_is_interactive()) { 168 if (len > 512) 169 len = 512; 170 } else { 171 /* Keep the packets at reasonable size. */ 172 if (len > packet_get_maxsize()) 173 len = packet_get_maxsize(); 174 } 175 packet_start(SSH_SMSG_STDERR_DATA); 176 packet_put_string(buffer_ptr(&stderr_buffer), len); 177 packet_send(); 178 buffer_consume(&stderr_buffer, len); 179 stderr_bytes += len; 180 } 181 } 182 183 /* 184 * Make packets from buffered stdout data, and buffer it for sending to the 185 * client. 186 */ 187 static void 188 make_packets_from_stdout_data(void) 189 { 190 u_int len; 191 192 /* Send buffered stdout data to the client. */ 193 while (buffer_len(&stdout_buffer) > 0 && 194 packet_not_very_much_data_to_write()) { 195 len = buffer_len(&stdout_buffer); 196 if (packet_is_interactive()) { 197 if (len > 512) 198 len = 512; 199 } else { 200 /* Keep the packets at reasonable size. */ 201 if (len > packet_get_maxsize()) 202 len = packet_get_maxsize(); 203 } 204 packet_start(SSH_SMSG_STDOUT_DATA); 205 packet_put_string(buffer_ptr(&stdout_buffer), len); 206 packet_send(); 207 buffer_consume(&stdout_buffer, len); 208 stdout_bytes += len; 209 } 210 } 211 212 static void 213 client_alive_check(void) 214 { 215 int channel_id; 216 217 /* timeout, check to see how many we have had */ 218 if (++client_alive_timeouts > options.client_alive_count_max) 219 packet_disconnect("Timeout, your session not responding."); 220 221 /* 222 * send a bogus global/channel request with "wantreply", 223 * we should get back a failure 224 */ 225 if ((channel_id = channel_find_open()) == -1) { 226 packet_start(SSH2_MSG_GLOBAL_REQUEST); 227 packet_put_cstring("keepalive@openssh.com"); 228 packet_put_char(1); /* boolean: want reply */ 229 } else { 230 channel_request_start(channel_id, "keepalive@openssh.com", 1); 231 } 232 packet_send(); 233 } 234 235 /* 236 * Sleep in select() until we can do something. This will initialize the 237 * select masks. Upon return, the masks will indicate which descriptors 238 * have data or can accept data. Optionally, a maximum time can be specified 239 * for the duration of the wait (0 = infinite). 240 */ 241 static void 242 wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp, 243 int *nallocp, u_int max_time_milliseconds) 244 { 245 struct timeval tv, *tvp; 246 int ret; 247 int client_alive_scheduled = 0; 248 249 /* 250 * if using client_alive, set the max timeout accordingly, 251 * and indicate that this particular timeout was for client 252 * alive by setting the client_alive_scheduled flag. 253 * 254 * this could be randomized somewhat to make traffic 255 * analysis more difficult, but we're not doing it yet. 256 */ 257 if (compat20 && 258 max_time_milliseconds == 0 && options.client_alive_interval) { 259 client_alive_scheduled = 1; 260 max_time_milliseconds = options.client_alive_interval * 1000; 261 } 262 263 /* Allocate and update select() masks for channel descriptors. */ 264 channel_prepare_select(readsetp, writesetp, maxfdp, nallocp, 0); 265 266 if (compat20) { 267 #if 0 268 /* wrong: bad condition XXX */ 269 if (channel_not_very_much_buffered_data()) 270 #endif 271 FD_SET(connection_in, *readsetp); 272 } else { 273 /* 274 * Read packets from the client unless we have too much 275 * buffered stdin or channel data. 276 */ 277 if (buffer_len(&stdin_buffer) < buffer_high && 278 channel_not_very_much_buffered_data()) 279 FD_SET(connection_in, *readsetp); 280 /* 281 * If there is not too much data already buffered going to 282 * the client, try to get some more data from the program. 283 */ 284 if (packet_not_very_much_data_to_write()) { 285 if (!fdout_eof) 286 FD_SET(fdout, *readsetp); 287 if (!fderr_eof) 288 FD_SET(fderr, *readsetp); 289 } 290 /* 291 * If we have buffered data, try to write some of that data 292 * to the program. 293 */ 294 if (fdin != -1 && buffer_len(&stdin_buffer) > 0) 295 FD_SET(fdin, *writesetp); 296 } 297 notify_prepare(*readsetp); 298 299 /* 300 * If we have buffered packet data going to the client, mark that 301 * descriptor. 302 */ 303 if (packet_have_data_to_write()) 304 FD_SET(connection_out, *writesetp); 305 306 /* 307 * If child has terminated and there is enough buffer space to read 308 * from it, then read as much as is available and exit. 309 */ 310 if (child_terminated && packet_not_very_much_data_to_write()) 311 if (max_time_milliseconds == 0 || client_alive_scheduled) 312 max_time_milliseconds = 100; 313 314 if (max_time_milliseconds == 0) 315 tvp = NULL; 316 else { 317 tv.tv_sec = max_time_milliseconds / 1000; 318 tv.tv_usec = 1000 * (max_time_milliseconds % 1000); 319 tvp = &tv; 320 } 321 322 /* Wait for something to happen, or the timeout to expire. */ 323 ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp); 324 325 if (ret == -1) { 326 memset(*readsetp, 0, *nallocp); 327 memset(*writesetp, 0, *nallocp); 328 if (errno != EINTR) 329 error("select: %.100s", strerror(errno)); 330 } else if (ret == 0 && client_alive_scheduled) 331 client_alive_check(); 332 333 notify_done(*readsetp); 334 } 335 336 /* 337 * Processes input from the client and the program. Input data is stored 338 * in buffers and processed later. 339 */ 340 static void 341 process_input(fd_set * readset) 342 { 343 int len; 344 char buf[16384]; 345 346 /* Read and buffer any input data from the client. */ 347 if (FD_ISSET(connection_in, readset)) { 348 len = read(connection_in, buf, sizeof(buf)); 349 if (len == 0) { 350 verbose("Connection closed by %.100s", 351 get_remote_ipaddr()); 352 connection_closed = 1; 353 if (compat20) 354 return; 355 cleanup_exit(255); 356 } else if (len < 0) { 357 if (errno != EINTR && errno != EAGAIN) { 358 verbose("Read error from remote host " 359 "%.100s: %.100s", 360 get_remote_ipaddr(), strerror(errno)); 361 cleanup_exit(255); 362 } 363 } else { 364 /* Buffer any received data. */ 365 packet_process_incoming(buf, len); 366 } 367 } 368 if (compat20) 369 return; 370 371 /* Read and buffer any available stdout data from the program. */ 372 if (!fdout_eof && FD_ISSET(fdout, readset)) { 373 len = read(fdout, buf, sizeof(buf)); 374 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 375 /* do nothing */ 376 } else if (len <= 0) { 377 fdout_eof = 1; 378 } else { 379 buffer_append(&stdout_buffer, buf, len); 380 fdout_bytes += len; 381 } 382 } 383 /* Read and buffer any available stderr data from the program. */ 384 if (!fderr_eof && FD_ISSET(fderr, readset)) { 385 len = read(fderr, buf, sizeof(buf)); 386 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 387 /* do nothing */ 388 } else if (len <= 0) { 389 fderr_eof = 1; 390 } else { 391 buffer_append(&stderr_buffer, buf, len); 392 } 393 } 394 } 395 396 /* 397 * Sends data from internal buffers to client program stdin. 398 */ 399 static void 400 process_output(fd_set * writeset) 401 { 402 struct termios tio; 403 u_char *data; 404 u_int dlen; 405 int len; 406 407 /* Write buffered data to program stdin. */ 408 if (!compat20 && fdin != -1 && FD_ISSET(fdin, writeset)) { 409 data = buffer_ptr(&stdin_buffer); 410 dlen = buffer_len(&stdin_buffer); 411 len = write(fdin, data, dlen); 412 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 413 /* do nothing */ 414 } else if (len <= 0) { 415 if (fdin != fdout) 416 close(fdin); 417 else 418 shutdown(fdin, SHUT_WR); /* We will no longer send. */ 419 fdin = -1; 420 } else { 421 /* Successful write. */ 422 if (fdin_is_tty && dlen >= 1 && data[0] != '\r' && 423 tcgetattr(fdin, &tio) == 0 && 424 !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) { 425 /* 426 * Simulate echo to reduce the impact of 427 * traffic analysis 428 */ 429 packet_send_ignore(len); 430 packet_send(); 431 } 432 /* Consume the data from the buffer. */ 433 buffer_consume(&stdin_buffer, len); 434 /* Update the count of bytes written to the program. */ 435 stdin_bytes += len; 436 } 437 } 438 /* Send any buffered packet data to the client. */ 439 if (FD_ISSET(connection_out, writeset)) 440 packet_write_poll(); 441 } 442 443 /* 444 * Wait until all buffered output has been sent to the client. 445 * This is used when the program terminates. 446 */ 447 static void 448 drain_output(void) 449 { 450 /* Send any buffered stdout data to the client. */ 451 if (buffer_len(&stdout_buffer) > 0) { 452 packet_start(SSH_SMSG_STDOUT_DATA); 453 packet_put_string(buffer_ptr(&stdout_buffer), 454 buffer_len(&stdout_buffer)); 455 packet_send(); 456 /* Update the count of sent bytes. */ 457 stdout_bytes += buffer_len(&stdout_buffer); 458 } 459 /* Send any buffered stderr data to the client. */ 460 if (buffer_len(&stderr_buffer) > 0) { 461 packet_start(SSH_SMSG_STDERR_DATA); 462 packet_put_string(buffer_ptr(&stderr_buffer), 463 buffer_len(&stderr_buffer)); 464 packet_send(); 465 /* Update the count of sent bytes. */ 466 stderr_bytes += buffer_len(&stderr_buffer); 467 } 468 /* Wait until all buffered data has been written to the client. */ 469 packet_write_wait(); 470 } 471 472 static void 473 process_buffered_input_packets(void) 474 { 475 dispatch_run(DISPATCH_NONBLOCK, NULL, compat20 ? xxx_kex : NULL); 476 } 477 478 /* 479 * Performs the interactive session. This handles data transmission between 480 * the client and the program. Note that the notion of stdin, stdout, and 481 * stderr in this function is sort of reversed: this function writes to 482 * stdin (of the child program), and reads from stdout and stderr (of the 483 * child program). 484 */ 485 void 486 server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg) 487 { 488 fd_set *readset = NULL, *writeset = NULL; 489 int max_fd = 0, nalloc = 0; 490 int wait_status; /* Status returned by wait(). */ 491 pid_t wait_pid; /* pid returned by wait(). */ 492 int waiting_termination = 0; /* Have displayed waiting close message. */ 493 u_int max_time_milliseconds; 494 u_int previous_stdout_buffer_bytes; 495 u_int stdout_buffer_bytes; 496 int type; 497 498 debug("Entering interactive session."); 499 500 /* Initialize the SIGCHLD kludge. */ 501 child_terminated = 0; 502 mysignal(SIGCHLD, sigchld_handler); 503 504 /* Initialize our global variables. */ 505 fdin = fdin_arg; 506 fdout = fdout_arg; 507 fderr = fderr_arg; 508 509 /* nonblocking IO */ 510 set_nonblock(fdin); 511 set_nonblock(fdout); 512 /* we don't have stderr for interactive terminal sessions, see below */ 513 if (fderr != -1) 514 set_nonblock(fderr); 515 516 if (!(datafellows & SSH_BUG_IGNOREMSG) && isatty(fdin)) 517 fdin_is_tty = 1; 518 519 connection_in = packet_get_connection_in(); 520 connection_out = packet_get_connection_out(); 521 522 notify_setup(); 523 524 previous_stdout_buffer_bytes = 0; 525 526 /* Set approximate I/O buffer size. */ 527 if (packet_is_interactive()) 528 buffer_high = 4096; 529 else 530 buffer_high = 64 * 1024; 531 532 #if 0 533 /* Initialize max_fd to the maximum of the known file descriptors. */ 534 max_fd = MAX(connection_in, connection_out); 535 max_fd = MAX(max_fd, fdin); 536 max_fd = MAX(max_fd, fdout); 537 if (fderr != -1) 538 max_fd = MAX(max_fd, fderr); 539 #endif 540 541 /* Initialize Initialize buffers. */ 542 buffer_init(&stdin_buffer); 543 buffer_init(&stdout_buffer); 544 buffer_init(&stderr_buffer); 545 546 /* 547 * If we have no separate fderr (which is the case when we have a pty 548 * - there we cannot make difference between data sent to stdout and 549 * stderr), indicate that we have seen an EOF from stderr. This way 550 * we don\'t need to check the descriptor everywhere. 551 */ 552 if (fderr == -1) 553 fderr_eof = 1; 554 555 server_init_dispatch(); 556 557 /* Main loop of the server for the interactive session mode. */ 558 for (;;) { 559 560 /* Process buffered packets from the client. */ 561 process_buffered_input_packets(); 562 563 /* 564 * If we have received eof, and there is no more pending 565 * input data, cause a real eof by closing fdin. 566 */ 567 if (stdin_eof && fdin != -1 && buffer_len(&stdin_buffer) == 0) { 568 if (fdin != fdout) 569 close(fdin); 570 else 571 shutdown(fdin, SHUT_WR); /* We will no longer send. */ 572 fdin = -1; 573 } 574 /* Make packets from buffered stderr data to send to the client. */ 575 make_packets_from_stderr_data(); 576 577 /* 578 * Make packets from buffered stdout data to send to the 579 * client. If there is very little to send, this arranges to 580 * not send them now, but to wait a short while to see if we 581 * are getting more data. This is necessary, as some systems 582 * wake up readers from a pty after each separate character. 583 */ 584 max_time_milliseconds = 0; 585 stdout_buffer_bytes = buffer_len(&stdout_buffer); 586 if (stdout_buffer_bytes != 0 && stdout_buffer_bytes < 256 && 587 stdout_buffer_bytes != previous_stdout_buffer_bytes) { 588 /* try again after a while */ 589 max_time_milliseconds = 10; 590 } else { 591 /* Send it now. */ 592 make_packets_from_stdout_data(); 593 } 594 previous_stdout_buffer_bytes = buffer_len(&stdout_buffer); 595 596 /* Send channel data to the client. */ 597 if (packet_not_very_much_data_to_write()) 598 channel_output_poll(); 599 600 /* 601 * Bail out of the loop if the program has closed its output 602 * descriptors, and we have no more data to send to the 603 * client, and there is no pending buffered data. 604 */ 605 if (fdout_eof && fderr_eof && !packet_have_data_to_write() && 606 buffer_len(&stdout_buffer) == 0 && buffer_len(&stderr_buffer) == 0) { 607 if (!channel_still_open()) 608 break; 609 if (!waiting_termination) { 610 const char *s = "Waiting for forwarded connections to terminate...\r\n"; 611 char *cp; 612 waiting_termination = 1; 613 buffer_append(&stderr_buffer, s, strlen(s)); 614 615 /* Display list of open channels. */ 616 cp = channel_open_message(); 617 buffer_append(&stderr_buffer, cp, strlen(cp)); 618 xfree(cp); 619 } 620 } 621 max_fd = MAX(connection_in, connection_out); 622 max_fd = MAX(max_fd, fdin); 623 max_fd = MAX(max_fd, fdout); 624 max_fd = MAX(max_fd, fderr); 625 max_fd = MAX(max_fd, notify_pipe[0]); 626 627 /* Sleep in select() until we can do something. */ 628 wait_until_can_do_something(&readset, &writeset, &max_fd, 629 &nalloc, max_time_milliseconds); 630 631 /* Process any channel events. */ 632 channel_after_select(readset, writeset); 633 634 /* Process input from the client and from program stdout/stderr. */ 635 process_input(readset); 636 637 /* Process output to the client and to program stdin. */ 638 process_output(writeset); 639 } 640 if (readset) 641 xfree(readset); 642 if (writeset) 643 xfree(writeset); 644 645 /* Cleanup and termination code. */ 646 647 /* Wait until all output has been sent to the client. */ 648 drain_output(); 649 650 debug("End of interactive session; stdin %ld, stdout (read %ld, sent %ld), stderr %ld bytes.", 651 stdin_bytes, fdout_bytes, stdout_bytes, stderr_bytes); 652 653 /* Free and clear the buffers. */ 654 buffer_free(&stdin_buffer); 655 buffer_free(&stdout_buffer); 656 buffer_free(&stderr_buffer); 657 658 /* Close the file descriptors. */ 659 if (fdout != -1) 660 close(fdout); 661 fdout = -1; 662 fdout_eof = 1; 663 if (fderr != -1) 664 close(fderr); 665 fderr = -1; 666 fderr_eof = 1; 667 if (fdin != -1) 668 close(fdin); 669 fdin = -1; 670 671 channel_free_all(); 672 673 /* We no longer want our SIGCHLD handler to be called. */ 674 mysignal(SIGCHLD, SIG_DFL); 675 676 while ((wait_pid = waitpid(-1, &wait_status, 0)) < 0) 677 if (errno != EINTR) 678 packet_disconnect("wait: %.100s", strerror(errno)); 679 if (wait_pid != pid) 680 error("Strange, wait returned pid %ld, expected %ld", 681 (long)wait_pid, (long)pid); 682 683 /* Check if it exited normally. */ 684 if (WIFEXITED(wait_status)) { 685 /* Yes, normal exit. Get exit status and send it to the client. */ 686 debug("Command exited with status %d.", WEXITSTATUS(wait_status)); 687 packet_start(SSH_SMSG_EXITSTATUS); 688 packet_put_int(WEXITSTATUS(wait_status)); 689 packet_send(); 690 packet_write_wait(); 691 692 /* 693 * Wait for exit confirmation. Note that there might be 694 * other packets coming before it; however, the program has 695 * already died so we just ignore them. The client is 696 * supposed to respond with the confirmation when it receives 697 * the exit status. 698 */ 699 do { 700 type = packet_read(); 701 } 702 while (type != SSH_CMSG_EXIT_CONFIRMATION); 703 704 debug("Received exit confirmation."); 705 return; 706 } 707 /* Check if the program terminated due to a signal. */ 708 if (WIFSIGNALED(wait_status)) 709 packet_disconnect("Command terminated on signal %d.", 710 WTERMSIG(wait_status)); 711 712 /* Some weird exit cause. Just exit. */ 713 packet_disconnect("wait returned status %04x.", wait_status); 714 /* NOTREACHED */ 715 } 716 717 static void 718 collect_children(void) 719 { 720 pid_t pid; 721 sigset_t oset, nset; 722 int status; 723 724 /* block SIGCHLD while we check for dead children */ 725 sigemptyset(&nset); 726 sigaddset(&nset, SIGCHLD); 727 sigprocmask(SIG_BLOCK, &nset, &oset); 728 if (child_terminated) { 729 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 730 (pid < 0 && errno == EINTR)) 731 if (pid > 0) 732 session_close_by_pid(pid, status); 733 child_terminated = 0; 734 } 735 sigprocmask(SIG_SETMASK, &oset, NULL); 736 } 737 738 void 739 server_loop2(Authctxt *authctxt) 740 { 741 fd_set *readset = NULL, *writeset = NULL; 742 int rekeying = 0, max_fd, nalloc = 0; 743 744 debug("Entering interactive session for SSH2."); 745 746 mysignal(SIGCHLD, sigchld_handler); 747 child_terminated = 0; 748 connection_in = packet_get_connection_in(); 749 connection_out = packet_get_connection_out(); 750 751 notify_setup(); 752 753 max_fd = MAX(connection_in, connection_out); 754 max_fd = MAX(max_fd, notify_pipe[0]); 755 756 server_init_dispatch(); 757 758 for (;;) { 759 process_buffered_input_packets(); 760 761 rekeying = (xxx_kex != NULL && !xxx_kex->done); 762 763 if (!rekeying && packet_not_very_much_data_to_write()) 764 channel_output_poll(); 765 wait_until_can_do_something(&readset, &writeset, &max_fd, 766 &nalloc, 0); 767 768 collect_children(); 769 if (!rekeying) { 770 channel_after_select(readset, writeset); 771 if (packet_need_rekeying()) { 772 debug("need rekeying"); 773 xxx_kex->done = 0; 774 kex_send_kexinit(xxx_kex); 775 } 776 } 777 process_input(readset); 778 if (connection_closed) 779 break; 780 process_output(writeset); 781 } 782 collect_children(); 783 784 if (readset) 785 xfree(readset); 786 if (writeset) 787 xfree(writeset); 788 789 /* free all channels, no more reads and writes */ 790 channel_free_all(); 791 792 /* free remaining sessions, e.g. remove wtmp entries */ 793 session_destroy_all(NULL); 794 } 795 796 static void 797 server_input_keep_alive(int type, u_int32_t seq, void *ctxt) 798 { 799 debug("Got %d/%u for keepalive", type, seq); 800 /* 801 * reset timeout, since we got a sane answer from the client. 802 * even if this was generated by something other than 803 * the bogus CHANNEL_REQUEST we send for keepalives. 804 */ 805 client_alive_timeouts = 0; 806 } 807 808 static void 809 server_input_stdin_data(int type, u_int32_t seq, void *ctxt) 810 { 811 char *data; 812 u_int data_len; 813 814 /* Stdin data from the client. Append it to the buffer. */ 815 /* Ignore any data if the client has closed stdin. */ 816 if (fdin == -1) 817 return; 818 data = packet_get_string(&data_len); 819 packet_check_eom(); 820 buffer_append(&stdin_buffer, data, data_len); 821 memset(data, 0, data_len); 822 xfree(data); 823 } 824 825 static void 826 server_input_eof(int type, u_int32_t seq, void *ctxt) 827 { 828 /* 829 * Eof from the client. The stdin descriptor to the 830 * program will be closed when all buffered data has 831 * drained. 832 */ 833 debug("EOF received for stdin."); 834 packet_check_eom(); 835 stdin_eof = 1; 836 } 837 838 static void 839 server_input_window_size(int type, u_int32_t seq, void *ctxt) 840 { 841 int row = packet_get_int(); 842 int col = packet_get_int(); 843 int xpixel = packet_get_int(); 844 int ypixel = packet_get_int(); 845 846 debug("Window change received."); 847 packet_check_eom(); 848 if (fdin != -1) 849 pty_change_window_size(fdin, row, col, xpixel, ypixel); 850 } 851 852 static Channel * 853 server_request_direct_tcpip(void) 854 { 855 Channel *c; 856 int sock; 857 char *target, *originator; 858 int target_port, originator_port; 859 860 target = packet_get_string(NULL); 861 target_port = packet_get_int(); 862 originator = packet_get_string(NULL); 863 originator_port = packet_get_int(); 864 packet_check_eom(); 865 866 debug("server_request_direct_tcpip: originator %s port %d, target %s port %d", 867 originator, originator_port, target, target_port); 868 869 /* XXX check permission */ 870 sock = channel_connect_to(target, target_port); 871 xfree(target); 872 xfree(originator); 873 if (sock < 0) 874 return NULL; 875 c = channel_new("direct-tcpip", SSH_CHANNEL_CONNECTING, 876 sock, sock, -1, CHAN_TCP_WINDOW_DEFAULT, 877 CHAN_TCP_PACKET_DEFAULT, 0, "direct-tcpip", 1); 878 return c; 879 } 880 881 static Channel * 882 server_request_session(void) 883 { 884 Channel *c; 885 886 debug("input_session_request"); 887 packet_check_eom(); 888 /* 889 * A server session has no fd to read or write until a 890 * CHANNEL_REQUEST for a shell is made, so we set the type to 891 * SSH_CHANNEL_LARVAL. Additionally, a callback for handling all 892 * CHANNEL_REQUEST messages is registered. 893 */ 894 c = channel_new("session", SSH_CHANNEL_LARVAL, 895 -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT, 896 0, "server-session", 1); 897 if (session_open(the_authctxt, c->self) != 1) { 898 debug("session open failed, free channel %d", c->self); 899 channel_free(c); 900 return NULL; 901 } 902 channel_register_cleanup(c->self, session_close_by_channel); 903 return c; 904 } 905 906 static void 907 server_input_channel_open(int type, u_int32_t seq, void *ctxt) 908 { 909 Channel *c = NULL; 910 char *ctype; 911 int rchan; 912 u_int rmaxpack, rwindow, len; 913 914 ctype = packet_get_string(&len); 915 rchan = packet_get_int(); 916 rwindow = packet_get_int(); 917 rmaxpack = packet_get_int(); 918 919 debug("server_input_channel_open: ctype %s rchan %d win %d max %d", 920 ctype, rchan, rwindow, rmaxpack); 921 922 if (strcmp(ctype, "session") == 0) { 923 c = server_request_session(); 924 } else if (strcmp(ctype, "direct-tcpip") == 0) { 925 c = server_request_direct_tcpip(); 926 } 927 if (c != NULL) { 928 debug("server_input_channel_open: confirm %s", ctype); 929 c->remote_id = rchan; 930 c->remote_window = rwindow; 931 c->remote_maxpacket = rmaxpack; 932 if (c->type != SSH_CHANNEL_CONNECTING) { 933 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION); 934 packet_put_int(c->remote_id); 935 packet_put_int(c->self); 936 packet_put_int(c->local_window); 937 packet_put_int(c->local_maxpacket); 938 packet_send(); 939 } 940 } else { 941 debug("server_input_channel_open: failure %s", ctype); 942 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE); 943 packet_put_int(rchan); 944 packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED); 945 if (!(datafellows & SSH_BUG_OPENFAILURE)) { 946 packet_put_cstring("open failed"); 947 packet_put_cstring(""); 948 } 949 packet_send(); 950 } 951 xfree(ctype); 952 } 953 954 static void 955 server_input_global_request(int type, u_int32_t seq, void *ctxt) 956 { 957 char *rtype; 958 int want_reply; 959 int success = 0; 960 961 rtype = packet_get_string(NULL); 962 want_reply = packet_get_char(); 963 debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply); 964 965 /* -R style forwarding */ 966 if (strcmp(rtype, "tcpip-forward") == 0) { 967 struct passwd *pw; 968 char *listen_address; 969 u_short listen_port; 970 971 pw = the_authctxt->pw; 972 if (pw == NULL || !the_authctxt->valid) 973 fatal("server_input_global_request: no/invalid user"); 974 listen_address = packet_get_string(NULL); 975 listen_port = (u_short)packet_get_int(); 976 debug("server_input_global_request: tcpip-forward listen %s port %d", 977 listen_address, listen_port); 978 979 /* check permissions */ 980 if (!options.allow_tcp_forwarding || 981 no_port_forwarding_flag 982 #ifndef NO_IPPORT_RESERVED_CONCEPT 983 || (listen_port < IPPORT_RESERVED && pw->pw_uid != 0) 984 #endif 985 ) { 986 success = 0; 987 packet_send_debug("Server has disabled port forwarding."); 988 } else { 989 /* Start listening on the port */ 990 success = channel_setup_remote_fwd_listener( 991 listen_address, listen_port, options.gateway_ports); 992 } 993 xfree(listen_address); 994 } 995 if (want_reply) { 996 packet_start(success ? 997 SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE); 998 packet_send(); 999 packet_write_wait(); 1000 } 1001 xfree(rtype); 1002 } 1003 static void 1004 server_input_channel_req(int type, u_int32_t seq, void *ctxt) 1005 { 1006 Channel *c; 1007 int id, reply, success = 0; 1008 char *rtype; 1009 1010 id = packet_get_int(); 1011 rtype = packet_get_string(NULL); 1012 reply = packet_get_char(); 1013 1014 debug("server_input_channel_req: channel %d request %s reply %d", 1015 id, rtype, reply); 1016 1017 if ((c = channel_lookup(id)) == NULL) 1018 packet_disconnect("server_input_channel_req: " 1019 "unknown channel %d", id); 1020 if (c->type == SSH_CHANNEL_LARVAL || c->type == SSH_CHANNEL_OPEN) 1021 success = session_input_channel_req(c, rtype); 1022 if (reply) { 1023 packet_start(success ? 1024 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE); 1025 packet_put_int(c->remote_id); 1026 packet_send(); 1027 } 1028 xfree(rtype); 1029 } 1030 1031 static void 1032 server_init_dispatch_20(void) 1033 { 1034 debug("server_init_dispatch_20"); 1035 dispatch_init(&dispatch_protocol_error); 1036 dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); 1037 dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data); 1038 dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); 1039 dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); 1040 dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open); 1041 dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 1042 dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 1043 dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req); 1044 dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); 1045 dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request); 1046 /* client_alive */ 1047 dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_keep_alive); 1048 dispatch_set(SSH2_MSG_REQUEST_SUCCESS, &server_input_keep_alive); 1049 dispatch_set(SSH2_MSG_REQUEST_FAILURE, &server_input_keep_alive); 1050 /* rekeying */ 1051 dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); 1052 } 1053 static void 1054 server_init_dispatch_13(void) 1055 { 1056 debug("server_init_dispatch_13"); 1057 dispatch_init(NULL); 1058 dispatch_set(SSH_CMSG_EOF, &server_input_eof); 1059 dispatch_set(SSH_CMSG_STDIN_DATA, &server_input_stdin_data); 1060 dispatch_set(SSH_CMSG_WINDOW_SIZE, &server_input_window_size); 1061 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close); 1062 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation); 1063 dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data); 1064 dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 1065 dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 1066 dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open); 1067 } 1068 static void 1069 server_init_dispatch_15(void) 1070 { 1071 server_init_dispatch_13(); 1072 debug("server_init_dispatch_15"); 1073 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof); 1074 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_oclose); 1075 } 1076 static void 1077 server_init_dispatch(void) 1078 { 1079 if (compat20) 1080 server_init_dispatch_20(); 1081 else if (compat13) 1082 server_init_dispatch_13(); 1083 else 1084 server_init_dispatch_15(); 1085 } 1086