1 /* $OpenBSD: session.c,v 1.241 2008/06/16 13:22:53 dtucker Exp $ */ 2 /* 3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 4 * All rights reserved 5 * 6 * As far as I am concerned, the code I have written for this software 7 * can be used freely for any purpose. Any derived versions of this 8 * software must be clearly marked as such, and if the derived work is 9 * incompatible with the protocol description in the RFC file, it must be 10 * called by a name other than "ssh" or "Secure Shell". 11 * 12 * SSH2 support by Markus Friedl. 13 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 14 * 15 * Redistribution and use in source and binary forms, with or without 16 * modification, are permitted provided that the following conditions 17 * are met: 18 * 1. Redistributions of source code must retain the above copyright 19 * notice, this list of conditions and the following disclaimer. 20 * 2. Redistributions in binary form must reproduce the above copyright 21 * notice, this list of conditions and the following disclaimer in the 22 * documentation and/or other materials provided with the distribution. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 25 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 26 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 27 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 28 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 29 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 30 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 31 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 32 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 33 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 34 */ 35 36 #include "includes.h" 37 __RCSID("$FreeBSD$"); 38 39 #include <sys/types.h> 40 #include <sys/param.h> 41 #ifdef HAVE_SYS_STAT_H 42 # include <sys/stat.h> 43 #endif 44 #include <sys/socket.h> 45 #include <sys/un.h> 46 #include <sys/wait.h> 47 48 #include <arpa/inet.h> 49 50 #include <errno.h> 51 #include <grp.h> 52 #ifdef HAVE_PATHS_H 53 #include <paths.h> 54 #endif 55 #include <pwd.h> 56 #include <signal.h> 57 #include <stdarg.h> 58 #include <stdio.h> 59 #include <stdlib.h> 60 #include <string.h> 61 #include <unistd.h> 62 63 #include "openbsd-compat/sys-queue.h" 64 #include "xmalloc.h" 65 #include "ssh.h" 66 #include "ssh1.h" 67 #include "ssh2.h" 68 #include "sshpty.h" 69 #include "packet.h" 70 #include "buffer.h" 71 #include "match.h" 72 #include "uidswap.h" 73 #include "compat.h" 74 #include "channels.h" 75 #include "key.h" 76 #include "cipher.h" 77 #ifdef GSSAPI 78 #include "ssh-gss.h" 79 #endif 80 #include "hostfile.h" 81 #include "auth.h" 82 #include "auth-options.h" 83 #include "pathnames.h" 84 #include "log.h" 85 #include "servconf.h" 86 #include "sshlogin.h" 87 #include "serverloop.h" 88 #include "canohost.h" 89 #include "misc.h" 90 #include "session.h" 91 #include "kex.h" 92 #include "monitor_wrap.h" 93 #include "sftp.h" 94 95 #if defined(KRB5) && defined(USE_AFS) 96 #include <kafs.h> 97 #endif 98 99 /* func */ 100 101 Session *session_new(void); 102 void session_set_fds(Session *, int, int, int, int); 103 void session_pty_cleanup(Session *); 104 void session_proctitle(Session *); 105 int session_setup_x11fwd(Session *); 106 int do_exec_pty(Session *, const char *); 107 int do_exec_no_pty(Session *, const char *); 108 int do_exec(Session *, const char *); 109 void do_login(Session *, const char *); 110 #ifdef LOGIN_NEEDS_UTMPX 111 static void do_pre_login(Session *s); 112 #endif 113 void do_child(Session *, const char *); 114 void do_motd(void); 115 int check_quietlogin(Session *, const char *); 116 117 static void do_authenticated1(Authctxt *); 118 static void do_authenticated2(Authctxt *); 119 120 static int session_pty_req(Session *); 121 122 /* import */ 123 extern ServerOptions options; 124 extern char *__progname; 125 extern int log_stderr; 126 extern int debug_flag; 127 extern u_int utmp_len; 128 extern int startup_pipe; 129 extern void destroy_sensitive_data(void); 130 extern Buffer loginmsg; 131 132 /* original command from peer. */ 133 const char *original_command = NULL; 134 135 /* data */ 136 static int sessions_first_unused = -1; 137 static int sessions_nalloc = 0; 138 static Session *sessions = NULL; 139 140 #define SUBSYSTEM_NONE 0 141 #define SUBSYSTEM_EXT 1 142 #define SUBSYSTEM_INT_SFTP 2 143 144 #ifdef HAVE_LOGIN_CAP 145 login_cap_t *lc; 146 #endif 147 148 static int is_child = 0; 149 150 /* Name and directory of socket for authentication agent forwarding. */ 151 static char *auth_sock_name = NULL; 152 static char *auth_sock_dir = NULL; 153 154 /* removes the agent forwarding socket */ 155 156 static void 157 auth_sock_cleanup_proc(struct passwd *pw) 158 { 159 if (auth_sock_name != NULL) { 160 temporarily_use_uid(pw); 161 unlink(auth_sock_name); 162 rmdir(auth_sock_dir); 163 auth_sock_name = NULL; 164 restore_uid(); 165 } 166 } 167 168 static int 169 auth_input_request_forwarding(struct passwd * pw) 170 { 171 Channel *nc; 172 int sock = -1; 173 struct sockaddr_un sunaddr; 174 175 if (auth_sock_name != NULL) { 176 error("authentication forwarding requested twice."); 177 return 0; 178 } 179 180 /* Temporarily drop privileged uid for mkdir/bind. */ 181 temporarily_use_uid(pw); 182 183 /* Allocate a buffer for the socket name, and format the name. */ 184 auth_sock_dir = xstrdup("/tmp/ssh-XXXXXXXXXX"); 185 186 /* Create private directory for socket */ 187 if (mkdtemp(auth_sock_dir) == NULL) { 188 packet_send_debug("Agent forwarding disabled: " 189 "mkdtemp() failed: %.100s", strerror(errno)); 190 restore_uid(); 191 xfree(auth_sock_dir); 192 auth_sock_dir = NULL; 193 goto authsock_err; 194 } 195 196 xasprintf(&auth_sock_name, "%s/agent.%ld", 197 auth_sock_dir, (long) getpid()); 198 199 /* Create the socket. */ 200 sock = socket(AF_UNIX, SOCK_STREAM, 0); 201 if (sock < 0) { 202 error("socket: %.100s", strerror(errno)); 203 restore_uid(); 204 goto authsock_err; 205 } 206 207 /* Bind it to the name. */ 208 memset(&sunaddr, 0, sizeof(sunaddr)); 209 sunaddr.sun_family = AF_UNIX; 210 strlcpy(sunaddr.sun_path, auth_sock_name, sizeof(sunaddr.sun_path)); 211 212 if (bind(sock, (struct sockaddr *)&sunaddr, sizeof(sunaddr)) < 0) { 213 error("bind: %.100s", strerror(errno)); 214 restore_uid(); 215 goto authsock_err; 216 } 217 218 /* Restore the privileged uid. */ 219 restore_uid(); 220 221 /* Start listening on the socket. */ 222 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) { 223 error("listen: %.100s", strerror(errno)); 224 goto authsock_err; 225 } 226 227 /* Allocate a channel for the authentication agent socket. */ 228 nc = channel_new("auth socket", 229 SSH_CHANNEL_AUTH_SOCKET, sock, sock, -1, 230 CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 231 0, "auth socket", 1); 232 strlcpy(nc->path, auth_sock_name, sizeof(nc->path)); 233 return 1; 234 235 authsock_err: 236 if (auth_sock_name != NULL) 237 xfree(auth_sock_name); 238 if (auth_sock_dir != NULL) { 239 rmdir(auth_sock_dir); 240 xfree(auth_sock_dir); 241 } 242 if (sock != -1) 243 close(sock); 244 auth_sock_name = NULL; 245 auth_sock_dir = NULL; 246 return 0; 247 } 248 249 static void 250 display_loginmsg(void) 251 { 252 if (buffer_len(&loginmsg) > 0) { 253 buffer_append(&loginmsg, "\0", 1); 254 printf("%s", (char *)buffer_ptr(&loginmsg)); 255 buffer_clear(&loginmsg); 256 } 257 } 258 259 void 260 do_authenticated(Authctxt *authctxt) 261 { 262 setproctitle("%s", authctxt->pw->pw_name); 263 264 /* setup the channel layer */ 265 if (!no_port_forwarding_flag && options.allow_tcp_forwarding) 266 channel_permit_all_opens(); 267 268 if (compat20) 269 do_authenticated2(authctxt); 270 else 271 do_authenticated1(authctxt); 272 273 do_cleanup(authctxt); 274 } 275 276 /* 277 * Prepares for an interactive session. This is called after the user has 278 * been successfully authenticated. During this message exchange, pseudo 279 * terminals are allocated, X11, TCP/IP, and authentication agent forwardings 280 * are requested, etc. 281 */ 282 static void 283 do_authenticated1(Authctxt *authctxt) 284 { 285 Session *s; 286 char *command; 287 int success, type, screen_flag; 288 int enable_compression_after_reply = 0; 289 u_int proto_len, data_len, dlen, compression_level = 0; 290 291 s = session_new(); 292 if (s == NULL) { 293 error("no more sessions"); 294 return; 295 } 296 s->authctxt = authctxt; 297 s->pw = authctxt->pw; 298 299 /* 300 * We stay in this loop until the client requests to execute a shell 301 * or a command. 302 */ 303 for (;;) { 304 success = 0; 305 306 /* Get a packet from the client. */ 307 type = packet_read(); 308 309 /* Process the packet. */ 310 switch (type) { 311 case SSH_CMSG_REQUEST_COMPRESSION: 312 compression_level = packet_get_int(); 313 packet_check_eom(); 314 if (compression_level < 1 || compression_level > 9) { 315 packet_send_debug("Received invalid compression level %d.", 316 compression_level); 317 break; 318 } 319 if (options.compression == COMP_NONE) { 320 debug2("compression disabled"); 321 break; 322 } 323 /* Enable compression after we have responded with SUCCESS. */ 324 enable_compression_after_reply = 1; 325 success = 1; 326 break; 327 328 case SSH_CMSG_REQUEST_PTY: 329 success = session_pty_req(s); 330 break; 331 332 case SSH_CMSG_X11_REQUEST_FORWARDING: 333 s->auth_proto = packet_get_string(&proto_len); 334 s->auth_data = packet_get_string(&data_len); 335 336 screen_flag = packet_get_protocol_flags() & 337 SSH_PROTOFLAG_SCREEN_NUMBER; 338 debug2("SSH_PROTOFLAG_SCREEN_NUMBER: %d", screen_flag); 339 340 if (packet_remaining() == 4) { 341 if (!screen_flag) 342 debug2("Buggy client: " 343 "X11 screen flag missing"); 344 s->screen = packet_get_int(); 345 } else { 346 s->screen = 0; 347 } 348 packet_check_eom(); 349 success = session_setup_x11fwd(s); 350 if (!success) { 351 xfree(s->auth_proto); 352 xfree(s->auth_data); 353 s->auth_proto = NULL; 354 s->auth_data = NULL; 355 } 356 break; 357 358 case SSH_CMSG_AGENT_REQUEST_FORWARDING: 359 if (!options.allow_agent_forwarding || 360 no_agent_forwarding_flag || compat13) { 361 debug("Authentication agent forwarding not permitted for this authentication."); 362 break; 363 } 364 debug("Received authentication agent forwarding request."); 365 success = auth_input_request_forwarding(s->pw); 366 break; 367 368 case SSH_CMSG_PORT_FORWARD_REQUEST: 369 if (no_port_forwarding_flag) { 370 debug("Port forwarding not permitted for this authentication."); 371 break; 372 } 373 if (!options.allow_tcp_forwarding) { 374 debug("Port forwarding not permitted."); 375 break; 376 } 377 debug("Received TCP/IP port forwarding request."); 378 if (channel_input_port_forward_request(s->pw->pw_uid == 0, 379 options.gateway_ports) < 0) { 380 debug("Port forwarding failed."); 381 break; 382 } 383 success = 1; 384 break; 385 386 case SSH_CMSG_MAX_PACKET_SIZE: 387 if (packet_set_maxsize(packet_get_int()) > 0) 388 success = 1; 389 break; 390 391 case SSH_CMSG_EXEC_SHELL: 392 case SSH_CMSG_EXEC_CMD: 393 if (type == SSH_CMSG_EXEC_CMD) { 394 command = packet_get_string(&dlen); 395 debug("Exec command '%.500s'", command); 396 if (do_exec(s, command) != 0) 397 packet_disconnect( 398 "command execution failed"); 399 xfree(command); 400 } else { 401 if (do_exec(s, NULL) != 0) 402 packet_disconnect( 403 "shell execution failed"); 404 } 405 packet_check_eom(); 406 session_close(s); 407 return; 408 409 default: 410 /* 411 * Any unknown messages in this phase are ignored, 412 * and a failure message is returned. 413 */ 414 logit("Unknown packet type received after authentication: %d", type); 415 } 416 packet_start(success ? SSH_SMSG_SUCCESS : SSH_SMSG_FAILURE); 417 packet_send(); 418 packet_write_wait(); 419 420 /* Enable compression now that we have replied if appropriate. */ 421 if (enable_compression_after_reply) { 422 enable_compression_after_reply = 0; 423 packet_start_compression(compression_level); 424 } 425 } 426 } 427 428 #define USE_PIPES 429 /* 430 * This is called to fork and execute a command when we have no tty. This 431 * will call do_child from the child, and server_loop from the parent after 432 * setting up file descriptors and such. 433 */ 434 int 435 do_exec_no_pty(Session *s, const char *command) 436 { 437 pid_t pid; 438 439 #ifdef USE_PIPES 440 int pin[2], pout[2], perr[2]; 441 442 /* Allocate pipes for communicating with the program. */ 443 if (pipe(pin) < 0) { 444 error("%s: pipe in: %.100s", __func__, strerror(errno)); 445 return -1; 446 } 447 if (pipe(pout) < 0) { 448 error("%s: pipe out: %.100s", __func__, strerror(errno)); 449 close(pin[0]); 450 close(pin[1]); 451 return -1; 452 } 453 if (pipe(perr) < 0) { 454 error("%s: pipe err: %.100s", __func__, strerror(errno)); 455 close(pin[0]); 456 close(pin[1]); 457 close(pout[0]); 458 close(pout[1]); 459 return -1; 460 } 461 #else 462 int inout[2], err[2]; 463 464 /* Uses socket pairs to communicate with the program. */ 465 if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) < 0) { 466 error("%s: socketpair #1: %.100s", __func__, strerror(errno)); 467 return -1; 468 } 469 if (socketpair(AF_UNIX, SOCK_STREAM, 0, err) < 0) { 470 error("%s: socketpair #2: %.100s", __func__, strerror(errno)); 471 close(inout[0]); 472 close(inout[1]); 473 return -1; 474 } 475 #endif 476 477 if (s == NULL) 478 fatal("do_exec_no_pty: no session"); 479 480 session_proctitle(s); 481 482 /* Fork the child. */ 483 switch ((pid = fork())) { 484 case -1: 485 error("%s: fork: %.100s", __func__, strerror(errno)); 486 #ifdef USE_PIPES 487 close(pin[0]); 488 close(pin[1]); 489 close(pout[0]); 490 close(pout[1]); 491 close(perr[0]); 492 close(perr[1]); 493 #else 494 close(inout[0]); 495 close(inout[1]); 496 close(err[0]); 497 close(err[1]); 498 #endif 499 return -1; 500 case 0: 501 is_child = 1; 502 503 /* Child. Reinitialize the log since the pid has changed. */ 504 log_init(__progname, options.log_level, 505 options.log_facility, log_stderr); 506 507 /* 508 * Create a new session and process group since the 4.4BSD 509 * setlogin() affects the entire process group. 510 */ 511 if (setsid() < 0) 512 error("setsid failed: %.100s", strerror(errno)); 513 514 #ifdef USE_PIPES 515 /* 516 * Redirect stdin. We close the parent side of the socket 517 * pair, and make the child side the standard input. 518 */ 519 close(pin[1]); 520 if (dup2(pin[0], 0) < 0) 521 perror("dup2 stdin"); 522 close(pin[0]); 523 524 /* Redirect stdout. */ 525 close(pout[0]); 526 if (dup2(pout[1], 1) < 0) 527 perror("dup2 stdout"); 528 close(pout[1]); 529 530 /* Redirect stderr. */ 531 close(perr[0]); 532 if (dup2(perr[1], 2) < 0) 533 perror("dup2 stderr"); 534 close(perr[1]); 535 #else 536 /* 537 * Redirect stdin, stdout, and stderr. Stdin and stdout will 538 * use the same socket, as some programs (particularly rdist) 539 * seem to depend on it. 540 */ 541 close(inout[1]); 542 close(err[1]); 543 if (dup2(inout[0], 0) < 0) /* stdin */ 544 perror("dup2 stdin"); 545 if (dup2(inout[0], 1) < 0) /* stdout (same as stdin) */ 546 perror("dup2 stdout"); 547 close(inout[0]); 548 if (dup2(err[0], 2) < 0) /* stderr */ 549 perror("dup2 stderr"); 550 close(err[0]); 551 #endif 552 553 554 #ifdef _UNICOS 555 cray_init_job(s->pw); /* set up cray jid and tmpdir */ 556 #endif 557 558 /* Do processing for the child (exec command etc). */ 559 do_child(s, command); 560 /* NOTREACHED */ 561 default: 562 break; 563 } 564 565 #ifdef _UNICOS 566 signal(WJSIGNAL, cray_job_termination_handler); 567 #endif /* _UNICOS */ 568 #ifdef HAVE_CYGWIN 569 if (is_winnt) 570 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); 571 #endif 572 573 s->pid = pid; 574 /* Set interactive/non-interactive mode. */ 575 packet_set_interactive(s->display != NULL); 576 577 /* 578 * Clear loginmsg, since it's the child's responsibility to display 579 * it to the user, otherwise multiple sessions may accumulate 580 * multiple copies of the login messages. 581 */ 582 buffer_clear(&loginmsg); 583 584 #ifdef USE_PIPES 585 /* We are the parent. Close the child sides of the pipes. */ 586 close(pin[0]); 587 close(pout[1]); 588 close(perr[1]); 589 590 if (compat20) { 591 if (s->is_subsystem) { 592 close(perr[0]); 593 perr[0] = -1; 594 } 595 session_set_fds(s, pin[1], pout[0], perr[0], 0); 596 } else { 597 /* Enter the interactive session. */ 598 server_loop(pid, pin[1], pout[0], perr[0]); 599 /* server_loop has closed pin[1], pout[0], and perr[0]. */ 600 } 601 #else 602 /* We are the parent. Close the child sides of the socket pairs. */ 603 close(inout[0]); 604 close(err[0]); 605 606 /* 607 * Enter the interactive session. Note: server_loop must be able to 608 * handle the case that fdin and fdout are the same. 609 */ 610 if (compat20) { 611 session_set_fds(s, inout[1], inout[1], 612 s->is_subsystem ? -1 : err[1], 0); 613 if (s->is_subsystem) 614 close(err[1]); 615 } else { 616 server_loop(pid, inout[1], inout[1], err[1]); 617 /* server_loop has closed inout[1] and err[1]. */ 618 } 619 #endif 620 return 0; 621 } 622 623 /* 624 * This is called to fork and execute a command when we have a tty. This 625 * will call do_child from the child, and server_loop from the parent after 626 * setting up file descriptors, controlling tty, updating wtmp, utmp, 627 * lastlog, and other such operations. 628 */ 629 int 630 do_exec_pty(Session *s, const char *command) 631 { 632 int fdout, ptyfd, ttyfd, ptymaster; 633 pid_t pid; 634 635 if (s == NULL) 636 fatal("do_exec_pty: no session"); 637 ptyfd = s->ptyfd; 638 ttyfd = s->ttyfd; 639 640 /* 641 * Create another descriptor of the pty master side for use as the 642 * standard input. We could use the original descriptor, but this 643 * simplifies code in server_loop. The descriptor is bidirectional. 644 * Do this before forking (and cleanup in the child) so as to 645 * detect and gracefully fail out-of-fd conditions. 646 */ 647 if ((fdout = dup(ptyfd)) < 0) { 648 error("%s: dup #1: %s", __func__, strerror(errno)); 649 close(ttyfd); 650 close(ptyfd); 651 return -1; 652 } 653 /* we keep a reference to the pty master */ 654 if ((ptymaster = dup(ptyfd)) < 0) { 655 error("%s: dup #2: %s", __func__, strerror(errno)); 656 close(ttyfd); 657 close(ptyfd); 658 close(fdout); 659 return -1; 660 } 661 662 /* Fork the child. */ 663 switch ((pid = fork())) { 664 case -1: 665 error("%s: fork: %.100s", __func__, strerror(errno)); 666 close(fdout); 667 close(ptymaster); 668 close(ttyfd); 669 close(ptyfd); 670 return -1; 671 case 0: 672 is_child = 1; 673 674 close(fdout); 675 close(ptymaster); 676 677 /* Child. Reinitialize the log because the pid has changed. */ 678 log_init(__progname, options.log_level, 679 options.log_facility, log_stderr); 680 /* Close the master side of the pseudo tty. */ 681 close(ptyfd); 682 683 /* Make the pseudo tty our controlling tty. */ 684 pty_make_controlling_tty(&ttyfd, s->tty); 685 686 /* Redirect stdin/stdout/stderr from the pseudo tty. */ 687 if (dup2(ttyfd, 0) < 0) 688 error("dup2 stdin: %s", strerror(errno)); 689 if (dup2(ttyfd, 1) < 0) 690 error("dup2 stdout: %s", strerror(errno)); 691 if (dup2(ttyfd, 2) < 0) 692 error("dup2 stderr: %s", strerror(errno)); 693 694 /* Close the extra descriptor for the pseudo tty. */ 695 close(ttyfd); 696 697 /* record login, etc. similar to login(1) */ 698 #ifndef HAVE_OSF_SIA 699 if (!(options.use_login && command == NULL)) { 700 #ifdef _UNICOS 701 cray_init_job(s->pw); /* set up cray jid and tmpdir */ 702 #endif /* _UNICOS */ 703 do_login(s, command); 704 } 705 # ifdef LOGIN_NEEDS_UTMPX 706 else 707 do_pre_login(s); 708 # endif 709 #endif 710 /* 711 * Do common processing for the child, such as execing 712 * the command. 713 */ 714 do_child(s, command); 715 /* NOTREACHED */ 716 default: 717 break; 718 } 719 720 #ifdef _UNICOS 721 signal(WJSIGNAL, cray_job_termination_handler); 722 #endif /* _UNICOS */ 723 #ifdef HAVE_CYGWIN 724 if (is_winnt) 725 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); 726 #endif 727 728 s->pid = pid; 729 730 /* Parent. Close the slave side of the pseudo tty. */ 731 close(ttyfd); 732 733 /* Enter interactive session. */ 734 s->ptymaster = ptymaster; 735 packet_set_interactive(1); 736 if (compat20) { 737 session_set_fds(s, ptyfd, fdout, -1, 1); 738 } else { 739 server_loop(pid, ptyfd, fdout, -1); 740 /* server_loop _has_ closed ptyfd and fdout. */ 741 } 742 return 0; 743 } 744 745 #ifdef LOGIN_NEEDS_UTMPX 746 static void 747 do_pre_login(Session *s) 748 { 749 socklen_t fromlen; 750 struct sockaddr_storage from; 751 pid_t pid = getpid(); 752 753 /* 754 * Get IP address of client. If the connection is not a socket, let 755 * the address be 0.0.0.0. 756 */ 757 memset(&from, 0, sizeof(from)); 758 fromlen = sizeof(from); 759 if (packet_connection_is_on_socket()) { 760 if (getpeername(packet_get_connection_in(), 761 (struct sockaddr *)&from, &fromlen) < 0) { 762 debug("getpeername: %.100s", strerror(errno)); 763 cleanup_exit(255); 764 } 765 } 766 767 record_utmp_only(pid, s->tty, s->pw->pw_name, 768 get_remote_name_or_ip(utmp_len, options.use_dns), 769 (struct sockaddr *)&from, fromlen); 770 } 771 #endif 772 773 /* 774 * This is called to fork and execute a command. If another command is 775 * to be forced, execute that instead. 776 */ 777 int 778 do_exec(Session *s, const char *command) 779 { 780 int ret; 781 782 if (options.adm_forced_command) { 783 original_command = command; 784 command = options.adm_forced_command; 785 if (strcmp(INTERNAL_SFTP_NAME, command) == 0) 786 s->is_subsystem = SUBSYSTEM_INT_SFTP; 787 else if (s->is_subsystem) 788 s->is_subsystem = SUBSYSTEM_EXT; 789 debug("Forced command (config) '%.900s'", command); 790 } else if (forced_command) { 791 original_command = command; 792 command = forced_command; 793 if (strcmp(INTERNAL_SFTP_NAME, command) == 0) 794 s->is_subsystem = SUBSYSTEM_INT_SFTP; 795 else if (s->is_subsystem) 796 s->is_subsystem = SUBSYSTEM_EXT; 797 debug("Forced command (key option) '%.900s'", command); 798 } 799 800 #ifdef SSH_AUDIT_EVENTS 801 if (command != NULL) 802 PRIVSEP(audit_run_command(command)); 803 else if (s->ttyfd == -1) { 804 char *shell = s->pw->pw_shell; 805 806 if (shell[0] == '\0') /* empty shell means /bin/sh */ 807 shell =_PATH_BSHELL; 808 PRIVSEP(audit_run_command(shell)); 809 } 810 #endif 811 if (s->ttyfd != -1) 812 ret = do_exec_pty(s, command); 813 else 814 ret = do_exec_no_pty(s, command); 815 816 original_command = NULL; 817 818 /* 819 * Clear loginmsg: it's the child's responsibility to display 820 * it to the user, otherwise multiple sessions may accumulate 821 * multiple copies of the login messages. 822 */ 823 buffer_clear(&loginmsg); 824 825 return ret; 826 } 827 828 /* administrative, login(1)-like work */ 829 void 830 do_login(Session *s, const char *command) 831 { 832 socklen_t fromlen; 833 struct sockaddr_storage from; 834 struct passwd * pw = s->pw; 835 pid_t pid = getpid(); 836 837 /* 838 * Get IP address of client. If the connection is not a socket, let 839 * the address be 0.0.0.0. 840 */ 841 memset(&from, 0, sizeof(from)); 842 fromlen = sizeof(from); 843 if (packet_connection_is_on_socket()) { 844 if (getpeername(packet_get_connection_in(), 845 (struct sockaddr *) & from, &fromlen) < 0) { 846 debug("getpeername: %.100s", strerror(errno)); 847 cleanup_exit(255); 848 } 849 } 850 851 /* Record that there was a login on that tty from the remote host. */ 852 if (!use_privsep) 853 record_login(pid, s->tty, pw->pw_name, pw->pw_uid, 854 get_remote_name_or_ip(utmp_len, 855 options.use_dns), 856 (struct sockaddr *)&from, fromlen); 857 858 #ifdef USE_PAM 859 /* 860 * If password change is needed, do it now. 861 * This needs to occur before the ~/.hushlogin check. 862 */ 863 if (options.use_pam && !use_privsep && s->authctxt->force_pwchange) { 864 display_loginmsg(); 865 do_pam_chauthtok(); 866 s->authctxt->force_pwchange = 0; 867 /* XXX - signal [net] parent to enable forwardings */ 868 } 869 #endif 870 871 if (check_quietlogin(s, command)) 872 return; 873 874 display_loginmsg(); 875 876 do_motd(); 877 } 878 879 /* 880 * Display the message of the day. 881 */ 882 void 883 do_motd(void) 884 { 885 FILE *f; 886 char buf[256]; 887 #ifdef HAVE_LOGIN_CAP 888 const char *fname; 889 #endif 890 891 #ifdef HAVE_LOGIN_CAP 892 fname = login_getcapstr(lc, "copyright", NULL, NULL); 893 if (fname != NULL && (f = fopen(fname, "r")) != NULL) { 894 while (fgets(buf, sizeof(buf), f) != NULL) 895 fputs(buf, stdout); 896 fclose(f); 897 } else 898 #endif /* HAVE_LOGIN_CAP */ 899 (void)printf("%s\n\t%s %s\n", 900 "Copyright (c) 1980, 1983, 1986, 1988, 1990, 1991, 1993, 1994", 901 "The Regents of the University of California. ", 902 "All rights reserved."); 903 904 (void)printf("\n"); 905 906 if (options.print_motd) { 907 #ifdef HAVE_LOGIN_CAP 908 f = fopen(login_getcapstr(lc, "welcome", "/etc/motd", 909 "/etc/motd"), "r"); 910 #else 911 f = fopen("/etc/motd", "r"); 912 #endif 913 if (f) { 914 while (fgets(buf, sizeof(buf), f)) 915 fputs(buf, stdout); 916 fclose(f); 917 } 918 } 919 } 920 921 922 /* 923 * Check for quiet login, either .hushlogin or command given. 924 */ 925 int 926 check_quietlogin(Session *s, const char *command) 927 { 928 char buf[256]; 929 struct passwd *pw = s->pw; 930 struct stat st; 931 932 /* Return 1 if .hushlogin exists or a command given. */ 933 if (command != NULL) 934 return 1; 935 snprintf(buf, sizeof(buf), "%.200s/.hushlogin", pw->pw_dir); 936 #ifdef HAVE_LOGIN_CAP 937 if (login_getcapbool(lc, "hushlogin", 0) || stat(buf, &st) >= 0) 938 return 1; 939 #else 940 if (stat(buf, &st) >= 0) 941 return 1; 942 #endif 943 return 0; 944 } 945 946 /* 947 * Sets the value of the given variable in the environment. If the variable 948 * already exists, its value is overriden. 949 */ 950 void 951 child_set_env(char ***envp, u_int *envsizep, const char *name, 952 const char *value) 953 { 954 char **env; 955 u_int envsize; 956 u_int i, namelen; 957 958 /* 959 * If we're passed an uninitialized list, allocate a single null 960 * entry before continuing. 961 */ 962 if (*envp == NULL && *envsizep == 0) { 963 *envp = xmalloc(sizeof(char *)); 964 *envp[0] = NULL; 965 *envsizep = 1; 966 } 967 968 /* 969 * Find the slot where the value should be stored. If the variable 970 * already exists, we reuse the slot; otherwise we append a new slot 971 * at the end of the array, expanding if necessary. 972 */ 973 env = *envp; 974 namelen = strlen(name); 975 for (i = 0; env[i]; i++) 976 if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=') 977 break; 978 if (env[i]) { 979 /* Reuse the slot. */ 980 xfree(env[i]); 981 } else { 982 /* New variable. Expand if necessary. */ 983 envsize = *envsizep; 984 if (i >= envsize - 1) { 985 if (envsize >= 1000) 986 fatal("child_set_env: too many env vars"); 987 envsize += 50; 988 env = (*envp) = xrealloc(env, envsize, sizeof(char *)); 989 *envsizep = envsize; 990 } 991 /* Need to set the NULL pointer at end of array beyond the new slot. */ 992 env[i + 1] = NULL; 993 } 994 995 /* Allocate space and format the variable in the appropriate slot. */ 996 env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1); 997 snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value); 998 } 999 1000 /* 1001 * Reads environment variables from the given file and adds/overrides them 1002 * into the environment. If the file does not exist, this does nothing. 1003 * Otherwise, it must consist of empty lines, comments (line starts with '#') 1004 * and assignments of the form name=value. No other forms are allowed. 1005 */ 1006 static void 1007 read_environment_file(char ***env, u_int *envsize, 1008 const char *filename) 1009 { 1010 FILE *f; 1011 char buf[4096]; 1012 char *cp, *value; 1013 u_int lineno = 0; 1014 1015 f = fopen(filename, "r"); 1016 if (!f) 1017 return; 1018 1019 while (fgets(buf, sizeof(buf), f)) { 1020 if (++lineno > 1000) 1021 fatal("Too many lines in environment file %s", filename); 1022 for (cp = buf; *cp == ' ' || *cp == '\t'; cp++) 1023 ; 1024 if (!*cp || *cp == '#' || *cp == '\n') 1025 continue; 1026 1027 cp[strcspn(cp, "\n")] = '\0'; 1028 1029 value = strchr(cp, '='); 1030 if (value == NULL) { 1031 fprintf(stderr, "Bad line %u in %.100s\n", lineno, 1032 filename); 1033 continue; 1034 } 1035 /* 1036 * Replace the equals sign by nul, and advance value to 1037 * the value string. 1038 */ 1039 *value = '\0'; 1040 value++; 1041 child_set_env(env, envsize, cp, value); 1042 } 1043 fclose(f); 1044 } 1045 1046 #ifdef HAVE_ETC_DEFAULT_LOGIN 1047 /* 1048 * Return named variable from specified environment, or NULL if not present. 1049 */ 1050 static char * 1051 child_get_env(char **env, const char *name) 1052 { 1053 int i; 1054 size_t len; 1055 1056 len = strlen(name); 1057 for (i=0; env[i] != NULL; i++) 1058 if (strncmp(name, env[i], len) == 0 && env[i][len] == '=') 1059 return(env[i] + len + 1); 1060 return NULL; 1061 } 1062 1063 /* 1064 * Read /etc/default/login. 1065 * We pick up the PATH (or SUPATH for root) and UMASK. 1066 */ 1067 static void 1068 read_etc_default_login(char ***env, u_int *envsize, uid_t uid) 1069 { 1070 char **tmpenv = NULL, *var; 1071 u_int i, tmpenvsize = 0; 1072 u_long mask; 1073 1074 /* 1075 * We don't want to copy the whole file to the child's environment, 1076 * so we use a temporary environment and copy the variables we're 1077 * interested in. 1078 */ 1079 read_environment_file(&tmpenv, &tmpenvsize, "/etc/default/login"); 1080 1081 if (tmpenv == NULL) 1082 return; 1083 1084 if (uid == 0) 1085 var = child_get_env(tmpenv, "SUPATH"); 1086 else 1087 var = child_get_env(tmpenv, "PATH"); 1088 if (var != NULL) 1089 child_set_env(env, envsize, "PATH", var); 1090 1091 if ((var = child_get_env(tmpenv, "UMASK")) != NULL) 1092 if (sscanf(var, "%5lo", &mask) == 1) 1093 umask((mode_t)mask); 1094 1095 for (i = 0; tmpenv[i] != NULL; i++) 1096 xfree(tmpenv[i]); 1097 xfree(tmpenv); 1098 } 1099 #endif /* HAVE_ETC_DEFAULT_LOGIN */ 1100 1101 void 1102 copy_environment(char **source, char ***env, u_int *envsize) 1103 { 1104 char *var_name, *var_val; 1105 int i; 1106 1107 if (source == NULL) 1108 return; 1109 1110 for(i = 0; source[i] != NULL; i++) { 1111 var_name = xstrdup(source[i]); 1112 if ((var_val = strstr(var_name, "=")) == NULL) { 1113 xfree(var_name); 1114 continue; 1115 } 1116 *var_val++ = '\0'; 1117 1118 debug3("Copy environment: %s=%s", var_name, var_val); 1119 child_set_env(env, envsize, var_name, var_val); 1120 1121 xfree(var_name); 1122 } 1123 } 1124 1125 static char ** 1126 do_setup_env(Session *s, const char *shell) 1127 { 1128 char buf[256]; 1129 u_int i, envsize; 1130 char **env, *laddr; 1131 struct passwd *pw = s->pw; 1132 #ifndef HAVE_LOGIN_CAP 1133 char *path = NULL; 1134 #else 1135 extern char **environ; 1136 char **senv, **var; 1137 #endif 1138 1139 /* Initialize the environment. */ 1140 envsize = 100; 1141 env = xcalloc(envsize, sizeof(char *)); 1142 env[0] = NULL; 1143 1144 #ifdef HAVE_CYGWIN 1145 /* 1146 * The Windows environment contains some setting which are 1147 * important for a running system. They must not be dropped. 1148 */ 1149 { 1150 char **p; 1151 1152 p = fetch_windows_environment(); 1153 copy_environment(p, &env, &envsize); 1154 free_windows_environment(p); 1155 } 1156 #endif 1157 1158 if (getenv("TZ")) 1159 child_set_env(&env, &envsize, "TZ", getenv("TZ")); 1160 1161 #ifdef GSSAPI 1162 /* Allow any GSSAPI methods that we've used to alter 1163 * the childs environment as they see fit 1164 */ 1165 ssh_gssapi_do_child(&env, &envsize); 1166 #endif 1167 1168 if (!options.use_login) { 1169 /* Set basic environment. */ 1170 for (i = 0; i < s->num_env; i++) 1171 child_set_env(&env, &envsize, s->env[i].name, 1172 s->env[i].val); 1173 1174 child_set_env(&env, &envsize, "USER", pw->pw_name); 1175 child_set_env(&env, &envsize, "LOGNAME", pw->pw_name); 1176 #ifdef _AIX 1177 child_set_env(&env, &envsize, "LOGIN", pw->pw_name); 1178 #endif 1179 child_set_env(&env, &envsize, "HOME", pw->pw_dir); 1180 snprintf(buf, sizeof buf, "%.200s/%.50s", 1181 _PATH_MAILDIR, pw->pw_name); 1182 child_set_env(&env, &envsize, "MAIL", buf); 1183 #ifdef HAVE_LOGIN_CAP 1184 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); 1185 child_set_env(&env, &envsize, "TERM", "su"); 1186 senv = environ; 1187 environ = xmalloc(sizeof(char *)); 1188 *environ = NULL; 1189 (void) setusercontext(lc, pw, pw->pw_uid, 1190 LOGIN_SETENV|LOGIN_SETPATH); 1191 copy_environment(environ, &env, &envsize); 1192 for (var = environ; *var != NULL; ++var) 1193 xfree(*var); 1194 xfree(environ); 1195 environ = senv; 1196 #else /* HAVE_LOGIN_CAP */ 1197 # ifndef HAVE_CYGWIN 1198 /* 1199 * There's no standard path on Windows. The path contains 1200 * important components pointing to the system directories, 1201 * needed for loading shared libraries. So the path better 1202 * remains intact here. 1203 */ 1204 # ifdef HAVE_ETC_DEFAULT_LOGIN 1205 read_etc_default_login(&env, &envsize, pw->pw_uid); 1206 path = child_get_env(env, "PATH"); 1207 # endif /* HAVE_ETC_DEFAULT_LOGIN */ 1208 if (path == NULL || *path == '\0') { 1209 child_set_env(&env, &envsize, "PATH", 1210 s->pw->pw_uid == 0 ? 1211 SUPERUSER_PATH : _PATH_STDPATH); 1212 } 1213 # endif /* HAVE_CYGWIN */ 1214 #endif /* HAVE_LOGIN_CAP */ 1215 1216 /* Normal systems set SHELL by default. */ 1217 child_set_env(&env, &envsize, "SHELL", shell); 1218 } 1219 1220 /* Set custom environment options from RSA authentication. */ 1221 if (!options.use_login) { 1222 while (custom_environment) { 1223 struct envstring *ce = custom_environment; 1224 char *str = ce->s; 1225 1226 for (i = 0; str[i] != '=' && str[i]; i++) 1227 ; 1228 if (str[i] == '=') { 1229 str[i] = 0; 1230 child_set_env(&env, &envsize, str, str + i + 1); 1231 } 1232 custom_environment = ce->next; 1233 xfree(ce->s); 1234 xfree(ce); 1235 } 1236 } 1237 1238 /* SSH_CLIENT deprecated */ 1239 snprintf(buf, sizeof buf, "%.50s %d %d", 1240 get_remote_ipaddr(), get_remote_port(), get_local_port()); 1241 child_set_env(&env, &envsize, "SSH_CLIENT", buf); 1242 1243 laddr = get_local_ipaddr(packet_get_connection_in()); 1244 snprintf(buf, sizeof buf, "%.50s %d %.50s %d", 1245 get_remote_ipaddr(), get_remote_port(), laddr, get_local_port()); 1246 xfree(laddr); 1247 child_set_env(&env, &envsize, "SSH_CONNECTION", buf); 1248 1249 if (s->ttyfd != -1) 1250 child_set_env(&env, &envsize, "SSH_TTY", s->tty); 1251 if (s->term) 1252 child_set_env(&env, &envsize, "TERM", s->term); 1253 if (s->display) 1254 child_set_env(&env, &envsize, "DISPLAY", s->display); 1255 if (original_command) 1256 child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND", 1257 original_command); 1258 1259 #ifdef _UNICOS 1260 if (cray_tmpdir[0] != '\0') 1261 child_set_env(&env, &envsize, "TMPDIR", cray_tmpdir); 1262 #endif /* _UNICOS */ 1263 1264 /* 1265 * Since we clear KRB5CCNAME at startup, if it's set now then it 1266 * must have been set by a native authentication method (eg AIX or 1267 * SIA), so copy it to the child. 1268 */ 1269 { 1270 char *cp; 1271 1272 if ((cp = getenv("KRB5CCNAME")) != NULL) 1273 child_set_env(&env, &envsize, "KRB5CCNAME", cp); 1274 } 1275 1276 #ifdef _AIX 1277 { 1278 char *cp; 1279 1280 if ((cp = getenv("AUTHSTATE")) != NULL) 1281 child_set_env(&env, &envsize, "AUTHSTATE", cp); 1282 read_environment_file(&env, &envsize, "/etc/environment"); 1283 } 1284 #endif 1285 #ifdef KRB5 1286 if (s->authctxt->krb5_ccname) 1287 child_set_env(&env, &envsize, "KRB5CCNAME", 1288 s->authctxt->krb5_ccname); 1289 #endif 1290 #ifdef USE_PAM 1291 /* 1292 * Pull in any environment variables that may have 1293 * been set by PAM. 1294 */ 1295 if (options.use_pam) { 1296 char **p; 1297 1298 p = fetch_pam_child_environment(); 1299 copy_environment(p, &env, &envsize); 1300 free_pam_environment(p); 1301 1302 p = fetch_pam_environment(); 1303 copy_environment(p, &env, &envsize); 1304 free_pam_environment(p); 1305 } 1306 #endif /* USE_PAM */ 1307 1308 if (auth_sock_name != NULL) 1309 child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME, 1310 auth_sock_name); 1311 1312 /* read $HOME/.ssh/environment. */ 1313 if (options.permit_user_env && !options.use_login) { 1314 snprintf(buf, sizeof buf, "%.200s/.ssh/environment", 1315 strcmp(pw->pw_dir, "/") ? pw->pw_dir : ""); 1316 read_environment_file(&env, &envsize, buf); 1317 } 1318 if (debug_flag) { 1319 /* dump the environment */ 1320 fprintf(stderr, "Environment:\n"); 1321 for (i = 0; env[i]; i++) 1322 fprintf(stderr, " %.200s\n", env[i]); 1323 } 1324 return env; 1325 } 1326 1327 /* 1328 * Run $HOME/.ssh/rc, /etc/ssh/sshrc, or xauth (whichever is found 1329 * first in this order). 1330 */ 1331 static void 1332 do_rc_files(Session *s, const char *shell) 1333 { 1334 FILE *f = NULL; 1335 char cmd[1024]; 1336 int do_xauth; 1337 struct stat st; 1338 1339 do_xauth = 1340 s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL; 1341 1342 /* ignore _PATH_SSH_USER_RC for subsystems and admin forced commands */ 1343 if (!s->is_subsystem && options.adm_forced_command == NULL && 1344 !no_user_rc && stat(_PATH_SSH_USER_RC, &st) >= 0) { 1345 snprintf(cmd, sizeof cmd, "%s -c '%s %s'", 1346 shell, _PATH_BSHELL, _PATH_SSH_USER_RC); 1347 if (debug_flag) 1348 fprintf(stderr, "Running %s\n", cmd); 1349 f = popen(cmd, "w"); 1350 if (f) { 1351 if (do_xauth) 1352 fprintf(f, "%s %s\n", s->auth_proto, 1353 s->auth_data); 1354 pclose(f); 1355 } else 1356 fprintf(stderr, "Could not run %s\n", 1357 _PATH_SSH_USER_RC); 1358 } else if (stat(_PATH_SSH_SYSTEM_RC, &st) >= 0) { 1359 if (debug_flag) 1360 fprintf(stderr, "Running %s %s\n", _PATH_BSHELL, 1361 _PATH_SSH_SYSTEM_RC); 1362 f = popen(_PATH_BSHELL " " _PATH_SSH_SYSTEM_RC, "w"); 1363 if (f) { 1364 if (do_xauth) 1365 fprintf(f, "%s %s\n", s->auth_proto, 1366 s->auth_data); 1367 pclose(f); 1368 } else 1369 fprintf(stderr, "Could not run %s\n", 1370 _PATH_SSH_SYSTEM_RC); 1371 } else if (do_xauth && options.xauth_location != NULL) { 1372 /* Add authority data to .Xauthority if appropriate. */ 1373 if (debug_flag) { 1374 fprintf(stderr, 1375 "Running %.500s remove %.100s\n", 1376 options.xauth_location, s->auth_display); 1377 fprintf(stderr, 1378 "%.500s add %.100s %.100s %.100s\n", 1379 options.xauth_location, s->auth_display, 1380 s->auth_proto, s->auth_data); 1381 } 1382 snprintf(cmd, sizeof cmd, "%s -q -", 1383 options.xauth_location); 1384 f = popen(cmd, "w"); 1385 if (f) { 1386 fprintf(f, "remove %s\n", 1387 s->auth_display); 1388 fprintf(f, "add %s %s %s\n", 1389 s->auth_display, s->auth_proto, 1390 s->auth_data); 1391 pclose(f); 1392 } else { 1393 fprintf(stderr, "Could not run %s\n", 1394 cmd); 1395 } 1396 } 1397 } 1398 1399 static void 1400 do_nologin(struct passwd *pw) 1401 { 1402 FILE *f = NULL; 1403 char buf[1024]; 1404 1405 #ifdef HAVE_LOGIN_CAP 1406 if (!login_getcapbool(lc, "ignorenologin", 0) && pw->pw_uid) 1407 f = fopen(login_getcapstr(lc, "nologin", _PATH_NOLOGIN, 1408 _PATH_NOLOGIN), "r"); 1409 #else 1410 if (pw->pw_uid) 1411 f = fopen(_PATH_NOLOGIN, "r"); 1412 #endif 1413 if (f) { 1414 /* /etc/nologin exists. Print its contents and exit. */ 1415 logit("User %.100s not allowed because %s exists", 1416 pw->pw_name, _PATH_NOLOGIN); 1417 while (fgets(buf, sizeof(buf), f)) 1418 fputs(buf, stderr); 1419 fclose(f); 1420 fflush(NULL); 1421 exit(254); 1422 } 1423 } 1424 1425 /* 1426 * Chroot into a directory after checking it for safety: all path components 1427 * must be root-owned directories with strict permissions. 1428 */ 1429 static void 1430 safely_chroot(const char *path, uid_t uid) 1431 { 1432 const char *cp; 1433 char component[MAXPATHLEN]; 1434 struct stat st; 1435 1436 if (*path != '/') 1437 fatal("chroot path does not begin at root"); 1438 if (strlen(path) >= sizeof(component)) 1439 fatal("chroot path too long"); 1440 1441 /* 1442 * Descend the path, checking that each component is a 1443 * root-owned directory with strict permissions. 1444 */ 1445 for (cp = path; cp != NULL;) { 1446 if ((cp = strchr(cp, '/')) == NULL) 1447 strlcpy(component, path, sizeof(component)); 1448 else { 1449 cp++; 1450 memcpy(component, path, cp - path); 1451 component[cp - path] = '\0'; 1452 } 1453 1454 debug3("%s: checking '%s'", __func__, component); 1455 1456 if (stat(component, &st) != 0) 1457 fatal("%s: stat(\"%s\"): %s", __func__, 1458 component, strerror(errno)); 1459 if (st.st_uid != 0 || (st.st_mode & 022) != 0) 1460 fatal("bad ownership or modes for chroot " 1461 "directory %s\"%s\"", 1462 cp == NULL ? "" : "component ", component); 1463 if (!S_ISDIR(st.st_mode)) 1464 fatal("chroot path %s\"%s\" is not a directory", 1465 cp == NULL ? "" : "component ", component); 1466 1467 } 1468 1469 if (chdir(path) == -1) 1470 fatal("Unable to chdir to chroot path \"%s\": " 1471 "%s", path, strerror(errno)); 1472 if (chroot(path) == -1) 1473 fatal("chroot(\"%s\"): %s", path, strerror(errno)); 1474 if (chdir("/") == -1) 1475 fatal("%s: chdir(/) after chroot: %s", 1476 __func__, strerror(errno)); 1477 verbose("Changed root directory to \"%s\"", path); 1478 } 1479 1480 /* Set login name, uid, gid, and groups. */ 1481 void 1482 do_setusercontext(struct passwd *pw) 1483 { 1484 char *chroot_path, *tmp; 1485 1486 #ifdef WITH_SELINUX 1487 /* Cache selinux status for later use */ 1488 (void)ssh_selinux_enabled(); 1489 #endif 1490 1491 #ifndef HAVE_CYGWIN 1492 if (getuid() == 0 || geteuid() == 0) 1493 #endif /* HAVE_CYGWIN */ 1494 { 1495 1496 #ifdef HAVE_SETPCRED 1497 if (setpcred(pw->pw_name, (char **)NULL) == -1) 1498 fatal("Failed to set process credentials"); 1499 #endif /* HAVE_SETPCRED */ 1500 #ifdef HAVE_LOGIN_CAP 1501 # ifdef __bsdi__ 1502 setpgid(0, 0); 1503 # endif 1504 # ifdef USE_PAM 1505 if (options.use_pam) { 1506 do_pam_setcred(use_privsep); 1507 } 1508 # endif /* USE_PAM */ 1509 if (setusercontext(lc, pw, pw->pw_uid, 1510 (LOGIN_SETALL & ~(LOGIN_SETENV|LOGIN_SETPATH|LOGIN_SETUSER))) < 0) { 1511 perror("unable to set user context"); 1512 exit(1); 1513 } 1514 #else 1515 # if defined(HAVE_GETLUID) && defined(HAVE_SETLUID) 1516 /* Sets login uid for accounting */ 1517 if (getluid() == -1 && setluid(pw->pw_uid) == -1) 1518 error("setluid: %s", strerror(errno)); 1519 # endif /* defined(HAVE_GETLUID) && defined(HAVE_SETLUID) */ 1520 1521 if (setlogin(pw->pw_name) < 0) 1522 error("setlogin failed: %s", strerror(errno)); 1523 if (setgid(pw->pw_gid) < 0) { 1524 perror("setgid"); 1525 exit(1); 1526 } 1527 /* Initialize the group list. */ 1528 if (initgroups(pw->pw_name, pw->pw_gid) < 0) { 1529 perror("initgroups"); 1530 exit(1); 1531 } 1532 endgrent(); 1533 # ifdef USE_PAM 1534 /* 1535 * PAM credentials may take the form of supplementary groups. 1536 * These will have been wiped by the above initgroups() call. 1537 * Reestablish them here. 1538 */ 1539 if (options.use_pam) { 1540 do_pam_setcred(use_privsep); 1541 } 1542 # endif /* USE_PAM */ 1543 # if defined(WITH_IRIX_PROJECT) || defined(WITH_IRIX_JOBS) || defined(WITH_IRIX_ARRAY) 1544 irix_setusercontext(pw); 1545 # endif /* defined(WITH_IRIX_PROJECT) || defined(WITH_IRIX_JOBS) || defined(WITH_IRIX_ARRAY) */ 1546 # ifdef _AIX 1547 aix_usrinfo(pw); 1548 # endif /* _AIX */ 1549 # ifdef USE_LIBIAF 1550 if (set_id(pw->pw_name) != 0) { 1551 exit(1); 1552 } 1553 # endif /* USE_LIBIAF */ 1554 #endif 1555 1556 if (options.chroot_directory != NULL && 1557 strcasecmp(options.chroot_directory, "none") != 0) { 1558 tmp = tilde_expand_filename(options.chroot_directory, 1559 pw->pw_uid); 1560 chroot_path = percent_expand(tmp, "h", pw->pw_dir, 1561 "u", pw->pw_name, (char *)NULL); 1562 safely_chroot(chroot_path, pw->pw_uid); 1563 free(tmp); 1564 free(chroot_path); 1565 } 1566 1567 #ifdef HAVE_LOGIN_CAP 1568 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUSER) < 0) { 1569 perror("unable to set user context (setuser)"); 1570 exit(1); 1571 } 1572 #else 1573 /* Permanently switch to the desired uid. */ 1574 permanently_set_uid(pw); 1575 #endif 1576 } 1577 1578 #ifdef HAVE_CYGWIN 1579 if (is_winnt) 1580 #endif 1581 if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) 1582 fatal("Failed to set uids to %u.", (u_int) pw->pw_uid); 1583 1584 #ifdef WITH_SELINUX 1585 ssh_selinux_setup_exec_context(pw->pw_name); 1586 #endif 1587 } 1588 1589 static void 1590 do_pwchange(Session *s) 1591 { 1592 fflush(NULL); 1593 fprintf(stderr, "WARNING: Your password has expired.\n"); 1594 if (s->ttyfd != -1) { 1595 fprintf(stderr, 1596 "You must change your password now and login again!\n"); 1597 #ifdef PASSWD_NEEDS_USERNAME 1598 execl(_PATH_PASSWD_PROG, "passwd", s->pw->pw_name, 1599 (char *)NULL); 1600 #else 1601 execl(_PATH_PASSWD_PROG, "passwd", (char *)NULL); 1602 #endif 1603 perror("passwd"); 1604 } else { 1605 fprintf(stderr, 1606 "Password change required but no TTY available.\n"); 1607 } 1608 exit(1); 1609 } 1610 1611 static void 1612 launch_login(struct passwd *pw, const char *hostname) 1613 { 1614 /* Launch login(1). */ 1615 1616 execl(LOGIN_PROGRAM, "login", "-h", hostname, 1617 #ifdef xxxLOGIN_NEEDS_TERM 1618 (s->term ? s->term : "unknown"), 1619 #endif /* LOGIN_NEEDS_TERM */ 1620 #ifdef LOGIN_NO_ENDOPT 1621 "-p", "-f", pw->pw_name, (char *)NULL); 1622 #else 1623 "-p", "-f", "--", pw->pw_name, (char *)NULL); 1624 #endif 1625 1626 /* Login couldn't be executed, die. */ 1627 1628 perror("login"); 1629 exit(1); 1630 } 1631 1632 static void 1633 child_close_fds(void) 1634 { 1635 int i; 1636 1637 if (packet_get_connection_in() == packet_get_connection_out()) 1638 close(packet_get_connection_in()); 1639 else { 1640 close(packet_get_connection_in()); 1641 close(packet_get_connection_out()); 1642 } 1643 /* 1644 * Close all descriptors related to channels. They will still remain 1645 * open in the parent. 1646 */ 1647 /* XXX better use close-on-exec? -markus */ 1648 channel_close_all(); 1649 1650 /* 1651 * Close any extra file descriptors. Note that there may still be 1652 * descriptors left by system functions. They will be closed later. 1653 */ 1654 endpwent(); 1655 1656 /* 1657 * Close any extra open file descriptors so that we don't have them 1658 * hanging around in clients. Note that we want to do this after 1659 * initgroups, because at least on Solaris 2.3 it leaves file 1660 * descriptors open. 1661 */ 1662 for (i = 3; i < 64; i++) 1663 close(i); 1664 } 1665 1666 /* 1667 * Performs common processing for the child, such as setting up the 1668 * environment, closing extra file descriptors, setting the user and group 1669 * ids, and executing the command or shell. 1670 */ 1671 #define ARGV_MAX 10 1672 void 1673 do_child(Session *s, const char *command) 1674 { 1675 extern char **environ; 1676 char **env; 1677 char *argv[ARGV_MAX]; 1678 const char *shell, *shell0, *hostname = NULL; 1679 struct passwd *pw = s->pw; 1680 int r = 0; 1681 1682 /* remove hostkey from the child's memory */ 1683 destroy_sensitive_data(); 1684 1685 /* Force a password change */ 1686 if (s->authctxt->force_pwchange) { 1687 do_setusercontext(pw); 1688 child_close_fds(); 1689 do_pwchange(s); 1690 exit(1); 1691 } 1692 1693 /* login(1) is only called if we execute the login shell */ 1694 if (options.use_login && command != NULL) 1695 options.use_login = 0; 1696 1697 #ifdef _UNICOS 1698 cray_setup(pw->pw_uid, pw->pw_name, command); 1699 #endif /* _UNICOS */ 1700 1701 /* 1702 * Login(1) does this as well, and it needs uid 0 for the "-h" 1703 * switch, so we let login(1) to this for us. 1704 */ 1705 if (!options.use_login) { 1706 #ifdef HAVE_OSF_SIA 1707 session_setup_sia(pw, s->ttyfd == -1 ? NULL : s->tty); 1708 if (!check_quietlogin(s, command)) 1709 do_motd(); 1710 #else /* HAVE_OSF_SIA */ 1711 /* When PAM is enabled we rely on it to do the nologin check */ 1712 if (!options.use_pam) 1713 do_nologin(pw); 1714 do_setusercontext(pw); 1715 /* 1716 * PAM session modules in do_setusercontext may have 1717 * generated messages, so if this in an interactive 1718 * login then display them too. 1719 */ 1720 if (!check_quietlogin(s, command)) 1721 display_loginmsg(); 1722 #endif /* HAVE_OSF_SIA */ 1723 } 1724 1725 #ifdef USE_PAM 1726 if (options.use_pam && !options.use_login && !is_pam_session_open()) { 1727 debug3("PAM session not opened, exiting"); 1728 display_loginmsg(); 1729 exit(254); 1730 } 1731 #endif 1732 1733 /* 1734 * Get the shell from the password data. An empty shell field is 1735 * legal, and means /bin/sh. 1736 */ 1737 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; 1738 1739 /* 1740 * Make sure $SHELL points to the shell from the password file, 1741 * even if shell is overridden from login.conf 1742 */ 1743 env = do_setup_env(s, shell); 1744 1745 #ifdef HAVE_LOGIN_CAP 1746 shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell); 1747 #endif 1748 1749 /* we have to stash the hostname before we close our socket. */ 1750 if (options.use_login) 1751 hostname = get_remote_name_or_ip(utmp_len, 1752 options.use_dns); 1753 /* 1754 * Close the connection descriptors; note that this is the child, and 1755 * the server will still have the socket open, and it is important 1756 * that we do not shutdown it. Note that the descriptors cannot be 1757 * closed before building the environment, as we call 1758 * get_remote_ipaddr there. 1759 */ 1760 child_close_fds(); 1761 1762 /* 1763 * Must take new environment into use so that .ssh/rc, 1764 * /etc/ssh/sshrc and xauth are run in the proper environment. 1765 */ 1766 environ = env; 1767 1768 #if defined(KRB5) && defined(USE_AFS) 1769 /* 1770 * At this point, we check to see if AFS is active and if we have 1771 * a valid Kerberos 5 TGT. If so, it seems like a good idea to see 1772 * if we can (and need to) extend the ticket into an AFS token. If 1773 * we don't do this, we run into potential problems if the user's 1774 * home directory is in AFS and it's not world-readable. 1775 */ 1776 1777 if (options.kerberos_get_afs_token && k_hasafs() && 1778 (s->authctxt->krb5_ctx != NULL)) { 1779 char cell[64]; 1780 1781 debug("Getting AFS token"); 1782 1783 k_setpag(); 1784 1785 if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0) 1786 krb5_afslog(s->authctxt->krb5_ctx, 1787 s->authctxt->krb5_fwd_ccache, cell, NULL); 1788 1789 krb5_afslog_home(s->authctxt->krb5_ctx, 1790 s->authctxt->krb5_fwd_ccache, NULL, NULL, pw->pw_dir); 1791 } 1792 #endif 1793 1794 /* Change current directory to the user's home directory. */ 1795 if (chdir(pw->pw_dir) < 0) { 1796 /* Suppress missing homedir warning for chroot case */ 1797 #ifdef HAVE_LOGIN_CAP 1798 r = login_getcapbool(lc, "requirehome", 0); 1799 #endif 1800 if (r || options.chroot_directory == NULL) 1801 fprintf(stderr, "Could not chdir to home " 1802 "directory %s: %s\n", pw->pw_dir, 1803 strerror(errno)); 1804 if (r) 1805 exit(1); 1806 } 1807 1808 closefrom(STDERR_FILENO + 1); 1809 1810 if (!options.use_login) 1811 do_rc_files(s, shell); 1812 1813 /* restore SIGPIPE for child */ 1814 signal(SIGPIPE, SIG_DFL); 1815 1816 if (s->is_subsystem == SUBSYSTEM_INT_SFTP) { 1817 extern int optind, optreset; 1818 int i; 1819 char *p, *args; 1820 1821 setproctitle("%s@internal-sftp-server", s->pw->pw_name); 1822 args = strdup(command ? command : "sftp-server"); 1823 for (i = 0, (p = strtok(args, " ")); p; (p = strtok(NULL, " "))) 1824 if (i < ARGV_MAX - 1) 1825 argv[i++] = p; 1826 argv[i] = NULL; 1827 optind = optreset = 1; 1828 __progname = argv[0]; 1829 exit(sftp_server_main(i, argv, s->pw)); 1830 } 1831 1832 if (options.use_login) { 1833 launch_login(pw, hostname); 1834 /* NEVERREACHED */ 1835 } 1836 1837 /* Get the last component of the shell name. */ 1838 if ((shell0 = strrchr(shell, '/')) != NULL) 1839 shell0++; 1840 else 1841 shell0 = shell; 1842 1843 /* 1844 * If we have no command, execute the shell. In this case, the shell 1845 * name to be passed in argv[0] is preceded by '-' to indicate that 1846 * this is a login shell. 1847 */ 1848 if (!command) { 1849 char argv0[256]; 1850 1851 /* Start the shell. Set initial character to '-'. */ 1852 argv0[0] = '-'; 1853 1854 if (strlcpy(argv0 + 1, shell0, sizeof(argv0) - 1) 1855 >= sizeof(argv0) - 1) { 1856 errno = EINVAL; 1857 perror(shell); 1858 exit(1); 1859 } 1860 1861 /* Execute the shell. */ 1862 argv[0] = argv0; 1863 argv[1] = NULL; 1864 execve(shell, argv, env); 1865 1866 /* Executing the shell failed. */ 1867 perror(shell); 1868 exit(1); 1869 } 1870 /* 1871 * Execute the command using the user's shell. This uses the -c 1872 * option to execute the command. 1873 */ 1874 argv[0] = (char *) shell0; 1875 argv[1] = "-c"; 1876 argv[2] = (char *) command; 1877 argv[3] = NULL; 1878 execve(shell, argv, env); 1879 perror(shell); 1880 exit(1); 1881 } 1882 1883 void 1884 session_unused(int id) 1885 { 1886 debug3("%s: session id %d unused", __func__, id); 1887 if (id >= options.max_sessions || 1888 id >= sessions_nalloc) { 1889 fatal("%s: insane session id %d (max %d nalloc %d)", 1890 __func__, id, options.max_sessions, sessions_nalloc); 1891 } 1892 bzero(&sessions[id], sizeof(*sessions)); 1893 sessions[id].self = id; 1894 sessions[id].used = 0; 1895 sessions[id].chanid = -1; 1896 sessions[id].ptyfd = -1; 1897 sessions[id].ttyfd = -1; 1898 sessions[id].ptymaster = -1; 1899 sessions[id].x11_chanids = NULL; 1900 sessions[id].next_unused = sessions_first_unused; 1901 sessions_first_unused = id; 1902 } 1903 1904 Session * 1905 session_new(void) 1906 { 1907 Session *s, *tmp; 1908 1909 if (sessions_first_unused == -1) { 1910 if (sessions_nalloc >= options.max_sessions) 1911 return NULL; 1912 debug2("%s: allocate (allocated %d max %d)", 1913 __func__, sessions_nalloc, options.max_sessions); 1914 tmp = xrealloc(sessions, sessions_nalloc + 1, 1915 sizeof(*sessions)); 1916 if (tmp == NULL) { 1917 error("%s: cannot allocate %d sessions", 1918 __func__, sessions_nalloc + 1); 1919 return NULL; 1920 } 1921 sessions = tmp; 1922 session_unused(sessions_nalloc++); 1923 } 1924 1925 if (sessions_first_unused >= sessions_nalloc || 1926 sessions_first_unused < 0) { 1927 fatal("%s: insane first_unused %d max %d nalloc %d", 1928 __func__, sessions_first_unused, options.max_sessions, 1929 sessions_nalloc); 1930 } 1931 1932 s = &sessions[sessions_first_unused]; 1933 if (s->used) { 1934 fatal("%s: session %d already used", 1935 __func__, sessions_first_unused); 1936 } 1937 sessions_first_unused = s->next_unused; 1938 s->used = 1; 1939 s->next_unused = -1; 1940 debug("session_new: session %d", s->self); 1941 1942 return s; 1943 } 1944 1945 static void 1946 session_dump(void) 1947 { 1948 int i; 1949 for (i = 0; i < sessions_nalloc; i++) { 1950 Session *s = &sessions[i]; 1951 1952 debug("dump: used %d next_unused %d session %d %p " 1953 "channel %d pid %ld", 1954 s->used, 1955 s->next_unused, 1956 s->self, 1957 s, 1958 s->chanid, 1959 (long)s->pid); 1960 } 1961 } 1962 1963 int 1964 session_open(Authctxt *authctxt, int chanid) 1965 { 1966 Session *s = session_new(); 1967 debug("session_open: channel %d", chanid); 1968 if (s == NULL) { 1969 error("no more sessions"); 1970 return 0; 1971 } 1972 s->authctxt = authctxt; 1973 s->pw = authctxt->pw; 1974 if (s->pw == NULL || !authctxt->valid) 1975 fatal("no user for session %d", s->self); 1976 debug("session_open: session %d: link with channel %d", s->self, chanid); 1977 s->chanid = chanid; 1978 return 1; 1979 } 1980 1981 Session * 1982 session_by_tty(char *tty) 1983 { 1984 int i; 1985 for (i = 0; i < sessions_nalloc; i++) { 1986 Session *s = &sessions[i]; 1987 if (s->used && s->ttyfd != -1 && strcmp(s->tty, tty) == 0) { 1988 debug("session_by_tty: session %d tty %s", i, tty); 1989 return s; 1990 } 1991 } 1992 debug("session_by_tty: unknown tty %.100s", tty); 1993 session_dump(); 1994 return NULL; 1995 } 1996 1997 static Session * 1998 session_by_channel(int id) 1999 { 2000 int i; 2001 for (i = 0; i < sessions_nalloc; i++) { 2002 Session *s = &sessions[i]; 2003 if (s->used && s->chanid == id) { 2004 debug("session_by_channel: session %d channel %d", 2005 i, id); 2006 return s; 2007 } 2008 } 2009 debug("session_by_channel: unknown channel %d", id); 2010 session_dump(); 2011 return NULL; 2012 } 2013 2014 static Session * 2015 session_by_x11_channel(int id) 2016 { 2017 int i, j; 2018 2019 for (i = 0; i < sessions_nalloc; i++) { 2020 Session *s = &sessions[i]; 2021 2022 if (s->x11_chanids == NULL || !s->used) 2023 continue; 2024 for (j = 0; s->x11_chanids[j] != -1; j++) { 2025 if (s->x11_chanids[j] == id) { 2026 debug("session_by_x11_channel: session %d " 2027 "channel %d", s->self, id); 2028 return s; 2029 } 2030 } 2031 } 2032 debug("session_by_x11_channel: unknown channel %d", id); 2033 session_dump(); 2034 return NULL; 2035 } 2036 2037 static Session * 2038 session_by_pid(pid_t pid) 2039 { 2040 int i; 2041 debug("session_by_pid: pid %ld", (long)pid); 2042 for (i = 0; i < sessions_nalloc; i++) { 2043 Session *s = &sessions[i]; 2044 if (s->used && s->pid == pid) 2045 return s; 2046 } 2047 error("session_by_pid: unknown pid %ld", (long)pid); 2048 session_dump(); 2049 return NULL; 2050 } 2051 2052 static int 2053 session_window_change_req(Session *s) 2054 { 2055 s->col = packet_get_int(); 2056 s->row = packet_get_int(); 2057 s->xpixel = packet_get_int(); 2058 s->ypixel = packet_get_int(); 2059 packet_check_eom(); 2060 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 2061 return 1; 2062 } 2063 2064 static int 2065 session_pty_req(Session *s) 2066 { 2067 u_int len; 2068 int n_bytes; 2069 2070 if (no_pty_flag) { 2071 debug("Allocating a pty not permitted for this authentication."); 2072 return 0; 2073 } 2074 if (s->ttyfd != -1) { 2075 packet_disconnect("Protocol error: you already have a pty."); 2076 return 0; 2077 } 2078 2079 s->term = packet_get_string(&len); 2080 2081 if (compat20) { 2082 s->col = packet_get_int(); 2083 s->row = packet_get_int(); 2084 } else { 2085 s->row = packet_get_int(); 2086 s->col = packet_get_int(); 2087 } 2088 s->xpixel = packet_get_int(); 2089 s->ypixel = packet_get_int(); 2090 2091 if (strcmp(s->term, "") == 0) { 2092 xfree(s->term); 2093 s->term = NULL; 2094 } 2095 2096 /* Allocate a pty and open it. */ 2097 debug("Allocating pty."); 2098 if (!PRIVSEP(pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, 2099 sizeof(s->tty)))) { 2100 if (s->term) 2101 xfree(s->term); 2102 s->term = NULL; 2103 s->ptyfd = -1; 2104 s->ttyfd = -1; 2105 error("session_pty_req: session %d alloc failed", s->self); 2106 return 0; 2107 } 2108 debug("session_pty_req: session %d alloc %s", s->self, s->tty); 2109 2110 /* for SSH1 the tty modes length is not given */ 2111 if (!compat20) 2112 n_bytes = packet_remaining(); 2113 tty_parse_modes(s->ttyfd, &n_bytes); 2114 2115 if (!use_privsep) 2116 pty_setowner(s->pw, s->tty); 2117 2118 /* Set window size from the packet. */ 2119 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 2120 2121 packet_check_eom(); 2122 session_proctitle(s); 2123 return 1; 2124 } 2125 2126 static int 2127 session_subsystem_req(Session *s) 2128 { 2129 struct stat st; 2130 u_int len; 2131 int success = 0; 2132 char *prog, *cmd, *subsys = packet_get_string(&len); 2133 u_int i; 2134 2135 packet_check_eom(); 2136 logit("subsystem request for %.100s", subsys); 2137 2138 for (i = 0; i < options.num_subsystems; i++) { 2139 if (strcmp(subsys, options.subsystem_name[i]) == 0) { 2140 prog = options.subsystem_command[i]; 2141 cmd = options.subsystem_args[i]; 2142 if (!strcmp(INTERNAL_SFTP_NAME, prog)) { 2143 s->is_subsystem = SUBSYSTEM_INT_SFTP; 2144 } else if (stat(prog, &st) < 0) { 2145 error("subsystem: cannot stat %s: %s", prog, 2146 strerror(errno)); 2147 break; 2148 } else { 2149 s->is_subsystem = SUBSYSTEM_EXT; 2150 } 2151 debug("subsystem: exec() %s", cmd); 2152 success = do_exec(s, cmd) == 0; 2153 break; 2154 } 2155 } 2156 2157 if (!success) 2158 logit("subsystem request for %.100s failed, subsystem not found", 2159 subsys); 2160 2161 xfree(subsys); 2162 return success; 2163 } 2164 2165 static int 2166 session_x11_req(Session *s) 2167 { 2168 int success; 2169 2170 if (s->auth_proto != NULL || s->auth_data != NULL) { 2171 error("session_x11_req: session %d: " 2172 "x11 forwarding already active", s->self); 2173 return 0; 2174 } 2175 s->single_connection = packet_get_char(); 2176 s->auth_proto = packet_get_string(NULL); 2177 s->auth_data = packet_get_string(NULL); 2178 s->screen = packet_get_int(); 2179 packet_check_eom(); 2180 2181 success = session_setup_x11fwd(s); 2182 if (!success) { 2183 xfree(s->auth_proto); 2184 xfree(s->auth_data); 2185 s->auth_proto = NULL; 2186 s->auth_data = NULL; 2187 } 2188 return success; 2189 } 2190 2191 static int 2192 session_shell_req(Session *s) 2193 { 2194 packet_check_eom(); 2195 return do_exec(s, NULL) == 0; 2196 } 2197 2198 static int 2199 session_exec_req(Session *s) 2200 { 2201 u_int len, success; 2202 2203 char *command = packet_get_string(&len); 2204 packet_check_eom(); 2205 success = do_exec(s, command) == 0; 2206 xfree(command); 2207 return success; 2208 } 2209 2210 static int 2211 session_break_req(Session *s) 2212 { 2213 2214 packet_get_int(); /* ignored */ 2215 packet_check_eom(); 2216 2217 if (s->ttyfd == -1 || tcsendbreak(s->ttyfd, 0) < 0) 2218 return 0; 2219 return 1; 2220 } 2221 2222 static int 2223 session_env_req(Session *s) 2224 { 2225 char *name, *val; 2226 u_int name_len, val_len, i; 2227 2228 name = packet_get_string(&name_len); 2229 val = packet_get_string(&val_len); 2230 packet_check_eom(); 2231 2232 /* Don't set too many environment variables */ 2233 if (s->num_env > 128) { 2234 debug2("Ignoring env request %s: too many env vars", name); 2235 goto fail; 2236 } 2237 2238 for (i = 0; i < options.num_accept_env; i++) { 2239 if (match_pattern(name, options.accept_env[i])) { 2240 debug2("Setting env %d: %s=%s", s->num_env, name, val); 2241 s->env = xrealloc(s->env, s->num_env + 1, 2242 sizeof(*s->env)); 2243 s->env[s->num_env].name = name; 2244 s->env[s->num_env].val = val; 2245 s->num_env++; 2246 return (1); 2247 } 2248 } 2249 debug2("Ignoring env request %s: disallowed name", name); 2250 2251 fail: 2252 xfree(name); 2253 xfree(val); 2254 return (0); 2255 } 2256 2257 static int 2258 session_auth_agent_req(Session *s) 2259 { 2260 static int called = 0; 2261 packet_check_eom(); 2262 if (no_agent_forwarding_flag || !options.allow_agent_forwarding) { 2263 debug("session_auth_agent_req: no_agent_forwarding_flag"); 2264 return 0; 2265 } 2266 if (called) { 2267 return 0; 2268 } else { 2269 called = 1; 2270 return auth_input_request_forwarding(s->pw); 2271 } 2272 } 2273 2274 int 2275 session_input_channel_req(Channel *c, const char *rtype) 2276 { 2277 int success = 0; 2278 Session *s; 2279 2280 if ((s = session_by_channel(c->self)) == NULL) { 2281 logit("session_input_channel_req: no session %d req %.100s", 2282 c->self, rtype); 2283 return 0; 2284 } 2285 debug("session_input_channel_req: session %d req %s", s->self, rtype); 2286 2287 /* 2288 * a session is in LARVAL state until a shell, a command 2289 * or a subsystem is executed 2290 */ 2291 if (c->type == SSH_CHANNEL_LARVAL) { 2292 if (strcmp(rtype, "shell") == 0) { 2293 success = session_shell_req(s); 2294 } else if (strcmp(rtype, "exec") == 0) { 2295 success = session_exec_req(s); 2296 } else if (strcmp(rtype, "pty-req") == 0) { 2297 success = session_pty_req(s); 2298 } else if (strcmp(rtype, "x11-req") == 0) { 2299 success = session_x11_req(s); 2300 } else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) { 2301 success = session_auth_agent_req(s); 2302 } else if (strcmp(rtype, "subsystem") == 0) { 2303 success = session_subsystem_req(s); 2304 } else if (strcmp(rtype, "env") == 0) { 2305 success = session_env_req(s); 2306 } 2307 } 2308 if (strcmp(rtype, "window-change") == 0) { 2309 success = session_window_change_req(s); 2310 } else if (strcmp(rtype, "break") == 0) { 2311 success = session_break_req(s); 2312 } 2313 2314 return success; 2315 } 2316 2317 void 2318 session_set_fds(Session *s, int fdin, int fdout, int fderr, int is_tty) 2319 { 2320 if (!compat20) 2321 fatal("session_set_fds: called for proto != 2.0"); 2322 /* 2323 * now that have a child and a pipe to the child, 2324 * we can activate our channel and register the fd's 2325 */ 2326 if (s->chanid == -1) 2327 fatal("no channel for session %d", s->self); 2328 channel_set_fds(s->chanid, 2329 fdout, fdin, fderr, 2330 fderr == -1 ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ, 2331 1, is_tty, CHAN_SES_WINDOW_DEFAULT); 2332 } 2333 2334 /* 2335 * Function to perform pty cleanup. Also called if we get aborted abnormally 2336 * (e.g., due to a dropped connection). 2337 */ 2338 void 2339 session_pty_cleanup2(Session *s) 2340 { 2341 if (s == NULL) { 2342 error("session_pty_cleanup: no session"); 2343 return; 2344 } 2345 if (s->ttyfd == -1) 2346 return; 2347 2348 debug("session_pty_cleanup: session %d release %s", s->self, s->tty); 2349 2350 /* Record that the user has logged out. */ 2351 if (s->pid != 0) 2352 record_logout(s->pid, s->tty, s->pw->pw_name); 2353 2354 /* Release the pseudo-tty. */ 2355 if (getuid() == 0) 2356 pty_release(s->tty); 2357 2358 /* 2359 * Close the server side of the socket pairs. We must do this after 2360 * the pty cleanup, so that another process doesn't get this pty 2361 * while we're still cleaning up. 2362 */ 2363 if (s->ptymaster != -1 && close(s->ptymaster) < 0) 2364 error("close(s->ptymaster/%d): %s", 2365 s->ptymaster, strerror(errno)); 2366 2367 /* unlink pty from session */ 2368 s->ttyfd = -1; 2369 } 2370 2371 void 2372 session_pty_cleanup(Session *s) 2373 { 2374 PRIVSEP(session_pty_cleanup2(s)); 2375 } 2376 2377 static char * 2378 sig2name(int sig) 2379 { 2380 #define SSH_SIG(x) if (sig == SIG ## x) return #x 2381 SSH_SIG(ABRT); 2382 SSH_SIG(ALRM); 2383 SSH_SIG(FPE); 2384 SSH_SIG(HUP); 2385 SSH_SIG(ILL); 2386 SSH_SIG(INT); 2387 SSH_SIG(KILL); 2388 SSH_SIG(PIPE); 2389 SSH_SIG(QUIT); 2390 SSH_SIG(SEGV); 2391 SSH_SIG(TERM); 2392 SSH_SIG(USR1); 2393 SSH_SIG(USR2); 2394 #undef SSH_SIG 2395 return "SIG@openssh.com"; 2396 } 2397 2398 static void 2399 session_close_x11(int id) 2400 { 2401 Channel *c; 2402 2403 if ((c = channel_by_id(id)) == NULL) { 2404 debug("session_close_x11: x11 channel %d missing", id); 2405 } else { 2406 /* Detach X11 listener */ 2407 debug("session_close_x11: detach x11 channel %d", id); 2408 channel_cancel_cleanup(id); 2409 if (c->ostate != CHAN_OUTPUT_CLOSED) 2410 chan_mark_dead(c); 2411 } 2412 } 2413 2414 static void 2415 session_close_single_x11(int id, void *arg) 2416 { 2417 Session *s; 2418 u_int i; 2419 2420 debug3("session_close_single_x11: channel %d", id); 2421 channel_cancel_cleanup(id); 2422 if ((s = session_by_x11_channel(id)) == NULL) 2423 fatal("session_close_single_x11: no x11 channel %d", id); 2424 for (i = 0; s->x11_chanids[i] != -1; i++) { 2425 debug("session_close_single_x11: session %d: " 2426 "closing channel %d", s->self, s->x11_chanids[i]); 2427 /* 2428 * The channel "id" is already closing, but make sure we 2429 * close all of its siblings. 2430 */ 2431 if (s->x11_chanids[i] != id) 2432 session_close_x11(s->x11_chanids[i]); 2433 } 2434 xfree(s->x11_chanids); 2435 s->x11_chanids = NULL; 2436 if (s->display) { 2437 xfree(s->display); 2438 s->display = NULL; 2439 } 2440 if (s->auth_proto) { 2441 xfree(s->auth_proto); 2442 s->auth_proto = NULL; 2443 } 2444 if (s->auth_data) { 2445 xfree(s->auth_data); 2446 s->auth_data = NULL; 2447 } 2448 if (s->auth_display) { 2449 xfree(s->auth_display); 2450 s->auth_display = NULL; 2451 } 2452 } 2453 2454 static void 2455 session_exit_message(Session *s, int status) 2456 { 2457 Channel *c; 2458 2459 if ((c = channel_lookup(s->chanid)) == NULL) 2460 fatal("session_exit_message: session %d: no channel %d", 2461 s->self, s->chanid); 2462 debug("session_exit_message: session %d channel %d pid %ld", 2463 s->self, s->chanid, (long)s->pid); 2464 2465 if (WIFEXITED(status)) { 2466 channel_request_start(s->chanid, "exit-status", 0); 2467 packet_put_int(WEXITSTATUS(status)); 2468 packet_send(); 2469 } else if (WIFSIGNALED(status)) { 2470 channel_request_start(s->chanid, "exit-signal", 0); 2471 packet_put_cstring(sig2name(WTERMSIG(status))); 2472 #ifdef WCOREDUMP 2473 packet_put_char(WCOREDUMP(status)? 1 : 0); 2474 #else /* WCOREDUMP */ 2475 packet_put_char(0); 2476 #endif /* WCOREDUMP */ 2477 packet_put_cstring(""); 2478 packet_put_cstring(""); 2479 packet_send(); 2480 } else { 2481 /* Some weird exit cause. Just exit. */ 2482 packet_disconnect("wait returned status %04x.", status); 2483 } 2484 2485 /* disconnect channel */ 2486 debug("session_exit_message: release channel %d", s->chanid); 2487 2488 /* 2489 * Adjust cleanup callback attachment to send close messages when 2490 * the channel gets EOF. The session will be then be closed 2491 * by session_close_by_channel when the childs close their fds. 2492 */ 2493 channel_register_cleanup(c->self, session_close_by_channel, 1); 2494 2495 /* 2496 * emulate a write failure with 'chan_write_failed', nobody will be 2497 * interested in data we write. 2498 * Note that we must not call 'chan_read_failed', since there could 2499 * be some more data waiting in the pipe. 2500 */ 2501 if (c->ostate != CHAN_OUTPUT_CLOSED) 2502 chan_write_failed(c); 2503 } 2504 2505 void 2506 session_close(Session *s) 2507 { 2508 u_int i; 2509 2510 debug("session_close: session %d pid %ld", s->self, (long)s->pid); 2511 if (s->ttyfd != -1) 2512 session_pty_cleanup(s); 2513 if (s->term) 2514 xfree(s->term); 2515 if (s->display) 2516 xfree(s->display); 2517 if (s->x11_chanids) 2518 xfree(s->x11_chanids); 2519 if (s->auth_display) 2520 xfree(s->auth_display); 2521 if (s->auth_data) 2522 xfree(s->auth_data); 2523 if (s->auth_proto) 2524 xfree(s->auth_proto); 2525 if (s->env != NULL) { 2526 for (i = 0; i < s->num_env; i++) { 2527 xfree(s->env[i].name); 2528 xfree(s->env[i].val); 2529 } 2530 xfree(s->env); 2531 } 2532 session_proctitle(s); 2533 session_unused(s->self); 2534 } 2535 2536 void 2537 session_close_by_pid(pid_t pid, int status) 2538 { 2539 Session *s = session_by_pid(pid); 2540 if (s == NULL) { 2541 debug("session_close_by_pid: no session for pid %ld", 2542 (long)pid); 2543 return; 2544 } 2545 if (s->chanid != -1) 2546 session_exit_message(s, status); 2547 if (s->ttyfd != -1) 2548 session_pty_cleanup(s); 2549 s->pid = 0; 2550 } 2551 2552 /* 2553 * this is called when a channel dies before 2554 * the session 'child' itself dies 2555 */ 2556 void 2557 session_close_by_channel(int id, void *arg) 2558 { 2559 Session *s = session_by_channel(id); 2560 u_int i; 2561 2562 if (s == NULL) { 2563 debug("session_close_by_channel: no session for id %d", id); 2564 return; 2565 } 2566 debug("session_close_by_channel: channel %d child %ld", 2567 id, (long)s->pid); 2568 if (s->pid != 0) { 2569 debug("session_close_by_channel: channel %d: has child", id); 2570 /* 2571 * delay detach of session, but release pty, since 2572 * the fd's to the child are already closed 2573 */ 2574 if (s->ttyfd != -1) 2575 session_pty_cleanup(s); 2576 return; 2577 } 2578 /* detach by removing callback */ 2579 channel_cancel_cleanup(s->chanid); 2580 2581 /* Close any X11 listeners associated with this session */ 2582 if (s->x11_chanids != NULL) { 2583 for (i = 0; s->x11_chanids[i] != -1; i++) { 2584 session_close_x11(s->x11_chanids[i]); 2585 s->x11_chanids[i] = -1; 2586 } 2587 } 2588 2589 s->chanid = -1; 2590 session_close(s); 2591 } 2592 2593 void 2594 session_destroy_all(void (*closefunc)(Session *)) 2595 { 2596 int i; 2597 for (i = 0; i < sessions_nalloc; i++) { 2598 Session *s = &sessions[i]; 2599 if (s->used) { 2600 if (closefunc != NULL) 2601 closefunc(s); 2602 else 2603 session_close(s); 2604 } 2605 } 2606 } 2607 2608 static char * 2609 session_tty_list(void) 2610 { 2611 static char buf[1024]; 2612 int i; 2613 char *cp; 2614 2615 buf[0] = '\0'; 2616 for (i = 0; i < sessions_nalloc; i++) { 2617 Session *s = &sessions[i]; 2618 if (s->used && s->ttyfd != -1) { 2619 2620 if (strncmp(s->tty, "/dev/", 5) != 0) { 2621 cp = strrchr(s->tty, '/'); 2622 cp = (cp == NULL) ? s->tty : cp + 1; 2623 } else 2624 cp = s->tty + 5; 2625 2626 if (buf[0] != '\0') 2627 strlcat(buf, ",", sizeof buf); 2628 strlcat(buf, cp, sizeof buf); 2629 } 2630 } 2631 if (buf[0] == '\0') 2632 strlcpy(buf, "notty", sizeof buf); 2633 return buf; 2634 } 2635 2636 void 2637 session_proctitle(Session *s) 2638 { 2639 if (s->pw == NULL) 2640 error("no user for session %d", s->self); 2641 else 2642 setproctitle("%s@%s", s->pw->pw_name, session_tty_list()); 2643 } 2644 2645 int 2646 session_setup_x11fwd(Session *s) 2647 { 2648 struct stat st; 2649 char display[512], auth_display[512]; 2650 char hostname[MAXHOSTNAMELEN]; 2651 u_int i; 2652 2653 if (no_x11_forwarding_flag) { 2654 packet_send_debug("X11 forwarding disabled in user configuration file."); 2655 return 0; 2656 } 2657 if (!options.x11_forwarding) { 2658 debug("X11 forwarding disabled in server configuration file."); 2659 return 0; 2660 } 2661 if (!options.xauth_location || 2662 (stat(options.xauth_location, &st) == -1)) { 2663 packet_send_debug("No xauth program; cannot forward with spoofing."); 2664 return 0; 2665 } 2666 if (options.use_login) { 2667 packet_send_debug("X11 forwarding disabled; " 2668 "not compatible with UseLogin=yes."); 2669 return 0; 2670 } 2671 if (s->display != NULL) { 2672 debug("X11 display already set."); 2673 return 0; 2674 } 2675 if (x11_create_display_inet(options.x11_display_offset, 2676 options.x11_use_localhost, s->single_connection, 2677 &s->display_number, &s->x11_chanids) == -1) { 2678 debug("x11_create_display_inet failed."); 2679 return 0; 2680 } 2681 for (i = 0; s->x11_chanids[i] != -1; i++) { 2682 channel_register_cleanup(s->x11_chanids[i], 2683 session_close_single_x11, 0); 2684 } 2685 2686 /* Set up a suitable value for the DISPLAY variable. */ 2687 if (gethostname(hostname, sizeof(hostname)) < 0) 2688 fatal("gethostname: %.100s", strerror(errno)); 2689 /* 2690 * auth_display must be used as the displayname when the 2691 * authorization entry is added with xauth(1). This will be 2692 * different than the DISPLAY string for localhost displays. 2693 */ 2694 if (options.x11_use_localhost) { 2695 snprintf(display, sizeof display, "localhost:%u.%u", 2696 s->display_number, s->screen); 2697 snprintf(auth_display, sizeof auth_display, "unix:%u.%u", 2698 s->display_number, s->screen); 2699 s->display = xstrdup(display); 2700 s->auth_display = xstrdup(auth_display); 2701 } else { 2702 #ifdef IPADDR_IN_DISPLAY 2703 struct hostent *he; 2704 struct in_addr my_addr; 2705 2706 he = gethostbyname(hostname); 2707 if (he == NULL) { 2708 error("Can't get IP address for X11 DISPLAY."); 2709 packet_send_debug("Can't get IP address for X11 DISPLAY."); 2710 return 0; 2711 } 2712 memcpy(&my_addr, he->h_addr_list[0], sizeof(struct in_addr)); 2713 snprintf(display, sizeof display, "%.50s:%u.%u", inet_ntoa(my_addr), 2714 s->display_number, s->screen); 2715 #else 2716 snprintf(display, sizeof display, "%.400s:%u.%u", hostname, 2717 s->display_number, s->screen); 2718 #endif 2719 s->display = xstrdup(display); 2720 s->auth_display = xstrdup(display); 2721 } 2722 2723 return 1; 2724 } 2725 2726 static void 2727 do_authenticated2(Authctxt *authctxt) 2728 { 2729 server_loop2(authctxt); 2730 } 2731 2732 void 2733 do_cleanup(Authctxt *authctxt) 2734 { 2735 static int called = 0; 2736 2737 debug("do_cleanup"); 2738 2739 /* no cleanup if we're in the child for login shell */ 2740 if (is_child) 2741 return; 2742 2743 /* avoid double cleanup */ 2744 if (called) 2745 return; 2746 called = 1; 2747 2748 if (authctxt == NULL) 2749 return; 2750 2751 #ifdef USE_PAM 2752 if (options.use_pam) { 2753 sshpam_cleanup(); 2754 sshpam_thread_cleanup(); 2755 } 2756 #endif 2757 2758 if (!authctxt->authenticated) 2759 return; 2760 2761 #ifdef KRB5 2762 if (options.kerberos_ticket_cleanup && 2763 authctxt->krb5_ctx) 2764 krb5_cleanup_proc(authctxt); 2765 #endif 2766 2767 #ifdef GSSAPI 2768 if (compat20 && options.gss_cleanup_creds) 2769 ssh_gssapi_cleanup_creds(); 2770 #endif 2771 2772 /* remove agent socket */ 2773 auth_sock_cleanup_proc(authctxt->pw); 2774 2775 /* 2776 * Cleanup ptys/utmp only if privsep is disabled, 2777 * or if running in monitor. 2778 */ 2779 if (!use_privsep || mm_is_monitor()) 2780 session_destroy_all(session_pty_cleanup2); 2781 } 2782