1 /* $OpenBSD: session.c,v 1.294 2018/03/03 03:15:51 djm 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 <ctype.h> 51 #include <errno.h> 52 #include <fcntl.h> 53 #include <grp.h> 54 #include <netdb.h> 55 #ifdef HAVE_PATHS_H 56 #include <paths.h> 57 #endif 58 #include <pwd.h> 59 #include <signal.h> 60 #include <stdarg.h> 61 #include <stdio.h> 62 #include <stdlib.h> 63 #include <string.h> 64 #include <unistd.h> 65 #include <limits.h> 66 67 #include "openbsd-compat/sys-queue.h" 68 #include "xmalloc.h" 69 #include "ssh.h" 70 #include "ssh2.h" 71 #include "sshpty.h" 72 #include "packet.h" 73 #include "buffer.h" 74 #include "match.h" 75 #include "uidswap.h" 76 #include "compat.h" 77 #include "channels.h" 78 #include "key.h" 79 #include "cipher.h" 80 #ifdef GSSAPI 81 #include "ssh-gss.h" 82 #endif 83 #include "hostfile.h" 84 #include "auth.h" 85 #include "auth-options.h" 86 #include "authfd.h" 87 #include "pathnames.h" 88 #include "log.h" 89 #include "misc.h" 90 #include "servconf.h" 91 #include "sshlogin.h" 92 #include "serverloop.h" 93 #include "canohost.h" 94 #include "session.h" 95 #include "kex.h" 96 #include "monitor_wrap.h" 97 #include "sftp.h" 98 #include "atomicio.h" 99 100 #if defined(KRB5) && defined(USE_AFS) 101 #include <kafs.h> 102 #endif 103 104 #ifdef WITH_SELINUX 105 #include <selinux/selinux.h> 106 #endif 107 108 #define IS_INTERNAL_SFTP(c) \ 109 (!strncmp(c, INTERNAL_SFTP_NAME, sizeof(INTERNAL_SFTP_NAME) - 1) && \ 110 (c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\0' || \ 111 c[sizeof(INTERNAL_SFTP_NAME) - 1] == ' ' || \ 112 c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\t')) 113 114 /* func */ 115 116 Session *session_new(void); 117 void session_set_fds(struct ssh *, Session *, int, int, int, int, int); 118 void session_pty_cleanup(Session *); 119 void session_proctitle(Session *); 120 int session_setup_x11fwd(struct ssh *, Session *); 121 int do_exec_pty(struct ssh *, Session *, const char *); 122 int do_exec_no_pty(struct ssh *, Session *, const char *); 123 int do_exec(struct ssh *, Session *, const char *); 124 void do_login(struct ssh *, Session *, const char *); 125 void do_child(struct ssh *, Session *, const char *); 126 #ifdef LOGIN_NEEDS_UTMPX 127 static void do_pre_login(Session *s); 128 #endif 129 void do_motd(void); 130 int check_quietlogin(Session *, const char *); 131 132 static void do_authenticated2(struct ssh *, Authctxt *); 133 134 static int session_pty_req(struct ssh *, Session *); 135 136 /* import */ 137 extern ServerOptions options; 138 extern char *__progname; 139 extern int debug_flag; 140 extern u_int utmp_len; 141 extern int startup_pipe; 142 extern void destroy_sensitive_data(void); 143 extern Buffer loginmsg; 144 extern struct sshauthopt *auth_opts; 145 char *tun_fwd_ifnames; /* serverloop.c */ 146 147 /* original command from peer. */ 148 const char *original_command = NULL; 149 150 /* data */ 151 static int sessions_first_unused = -1; 152 static int sessions_nalloc = 0; 153 static Session *sessions = NULL; 154 155 #define SUBSYSTEM_NONE 0 156 #define SUBSYSTEM_EXT 1 157 #define SUBSYSTEM_INT_SFTP 2 158 #define SUBSYSTEM_INT_SFTP_ERROR 3 159 160 #ifdef HAVE_LOGIN_CAP 161 login_cap_t *lc; 162 #endif 163 164 static int is_child = 0; 165 static int in_chroot = 0; 166 167 /* File containing userauth info, if ExposeAuthInfo set */ 168 static char *auth_info_file = NULL; 169 170 /* Name and directory of socket for authentication agent forwarding. */ 171 static char *auth_sock_name = NULL; 172 static char *auth_sock_dir = NULL; 173 174 /* removes the agent forwarding socket */ 175 176 static void 177 auth_sock_cleanup_proc(struct passwd *pw) 178 { 179 if (auth_sock_name != NULL) { 180 temporarily_use_uid(pw); 181 unlink(auth_sock_name); 182 rmdir(auth_sock_dir); 183 auth_sock_name = NULL; 184 restore_uid(); 185 } 186 } 187 188 static int 189 auth_input_request_forwarding(struct ssh *ssh, struct passwd * pw) 190 { 191 Channel *nc; 192 int sock = -1; 193 194 if (auth_sock_name != NULL) { 195 error("authentication forwarding requested twice."); 196 return 0; 197 } 198 199 /* Temporarily drop privileged uid for mkdir/bind. */ 200 temporarily_use_uid(pw); 201 202 /* Allocate a buffer for the socket name, and format the name. */ 203 auth_sock_dir = xstrdup("/tmp/ssh-XXXXXXXXXX"); 204 205 /* Create private directory for socket */ 206 if (mkdtemp(auth_sock_dir) == NULL) { 207 packet_send_debug("Agent forwarding disabled: " 208 "mkdtemp() failed: %.100s", strerror(errno)); 209 restore_uid(); 210 free(auth_sock_dir); 211 auth_sock_dir = NULL; 212 goto authsock_err; 213 } 214 215 xasprintf(&auth_sock_name, "%s/agent.%ld", 216 auth_sock_dir, (long) getpid()); 217 218 /* Start a Unix listener on auth_sock_name. */ 219 sock = unix_listener(auth_sock_name, SSH_LISTEN_BACKLOG, 0); 220 221 /* Restore the privileged uid. */ 222 restore_uid(); 223 224 /* Check for socket/bind/listen failure. */ 225 if (sock < 0) 226 goto authsock_err; 227 228 /* Allocate a channel for the authentication agent socket. */ 229 nc = channel_new(ssh, "auth socket", 230 SSH_CHANNEL_AUTH_SOCKET, sock, sock, -1, 231 CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 232 0, "auth socket", 1); 233 nc->path = xstrdup(auth_sock_name); 234 return 1; 235 236 authsock_err: 237 free(auth_sock_name); 238 if (auth_sock_dir != NULL) { 239 rmdir(auth_sock_dir); 240 free(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 static void 260 prepare_auth_info_file(struct passwd *pw, struct sshbuf *info) 261 { 262 int fd = -1, success = 0; 263 264 if (!options.expose_userauth_info || info == NULL) 265 return; 266 267 temporarily_use_uid(pw); 268 auth_info_file = xstrdup("/tmp/sshauth.XXXXXXXXXXXXXXX"); 269 if ((fd = mkstemp(auth_info_file)) == -1) { 270 error("%s: mkstemp: %s", __func__, strerror(errno)); 271 goto out; 272 } 273 if (atomicio(vwrite, fd, sshbuf_mutable_ptr(info), 274 sshbuf_len(info)) != sshbuf_len(info)) { 275 error("%s: write: %s", __func__, strerror(errno)); 276 goto out; 277 } 278 if (close(fd) != 0) { 279 error("%s: close: %s", __func__, strerror(errno)); 280 goto out; 281 } 282 success = 1; 283 out: 284 if (!success) { 285 if (fd != -1) 286 close(fd); 287 free(auth_info_file); 288 auth_info_file = NULL; 289 } 290 restore_uid(); 291 } 292 293 static void 294 set_permitopen_from_authopts(struct ssh *ssh, const struct sshauthopt *opts) 295 { 296 char *tmp, *cp, *host; 297 int port; 298 size_t i; 299 300 if ((options.allow_tcp_forwarding & FORWARD_LOCAL) == 0) 301 return; 302 channel_clear_permitted_opens(ssh); 303 for (i = 0; i < auth_opts->npermitopen; i++) { 304 tmp = cp = xstrdup(auth_opts->permitopen[i]); 305 /* This shouldn't fail as it has already been checked */ 306 if ((host = hpdelim(&cp)) == NULL) 307 fatal("%s: internal error: hpdelim", __func__); 308 host = cleanhostname(host); 309 if (cp == NULL || (port = permitopen_port(cp)) < 0) 310 fatal("%s: internal error: permitopen port", 311 __func__); 312 channel_add_permitted_opens(ssh, host, port); 313 free(tmp); 314 } 315 } 316 317 void 318 do_authenticated(struct ssh *ssh, Authctxt *authctxt) 319 { 320 setproctitle("%s", authctxt->pw->pw_name); 321 322 auth_log_authopts("active", auth_opts, 0); 323 324 /* setup the channel layer */ 325 /* XXX - streamlocal? */ 326 set_permitopen_from_authopts(ssh, auth_opts); 327 if (!auth_opts->permit_port_forwarding_flag || 328 options.disable_forwarding || 329 (options.allow_tcp_forwarding & FORWARD_LOCAL) == 0) 330 channel_disable_adm_local_opens(ssh); 331 else 332 channel_permit_all_opens(ssh); 333 334 auth_debug_send(); 335 336 prepare_auth_info_file(authctxt->pw, authctxt->session_info); 337 338 do_authenticated2(ssh, authctxt); 339 340 do_cleanup(ssh, authctxt); 341 } 342 343 /* Check untrusted xauth strings for metacharacters */ 344 static int 345 xauth_valid_string(const char *s) 346 { 347 size_t i; 348 349 for (i = 0; s[i] != '\0'; i++) { 350 if (!isalnum((u_char)s[i]) && 351 s[i] != '.' && s[i] != ':' && s[i] != '/' && 352 s[i] != '-' && s[i] != '_') 353 return 0; 354 } 355 return 1; 356 } 357 358 #define USE_PIPES 1 359 /* 360 * This is called to fork and execute a command when we have no tty. This 361 * will call do_child from the child, and server_loop from the parent after 362 * setting up file descriptors and such. 363 */ 364 int 365 do_exec_no_pty(struct ssh *ssh, Session *s, const char *command) 366 { 367 pid_t pid; 368 #ifdef USE_PIPES 369 int pin[2], pout[2], perr[2]; 370 371 if (s == NULL) 372 fatal("do_exec_no_pty: no session"); 373 374 /* Allocate pipes for communicating with the program. */ 375 if (pipe(pin) < 0) { 376 error("%s: pipe in: %.100s", __func__, strerror(errno)); 377 return -1; 378 } 379 if (pipe(pout) < 0) { 380 error("%s: pipe out: %.100s", __func__, strerror(errno)); 381 close(pin[0]); 382 close(pin[1]); 383 return -1; 384 } 385 if (pipe(perr) < 0) { 386 error("%s: pipe err: %.100s", __func__, 387 strerror(errno)); 388 close(pin[0]); 389 close(pin[1]); 390 close(pout[0]); 391 close(pout[1]); 392 return -1; 393 } 394 #else 395 int inout[2], err[2]; 396 397 if (s == NULL) 398 fatal("do_exec_no_pty: no session"); 399 400 /* Uses socket pairs to communicate with the program. */ 401 if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) < 0) { 402 error("%s: socketpair #1: %.100s", __func__, strerror(errno)); 403 return -1; 404 } 405 if (socketpair(AF_UNIX, SOCK_STREAM, 0, err) < 0) { 406 error("%s: socketpair #2: %.100s", __func__, 407 strerror(errno)); 408 close(inout[0]); 409 close(inout[1]); 410 return -1; 411 } 412 #endif 413 414 session_proctitle(s); 415 416 /* Fork the child. */ 417 switch ((pid = fork())) { 418 case -1: 419 error("%s: fork: %.100s", __func__, strerror(errno)); 420 #ifdef USE_PIPES 421 close(pin[0]); 422 close(pin[1]); 423 close(pout[0]); 424 close(pout[1]); 425 close(perr[0]); 426 close(perr[1]); 427 #else 428 close(inout[0]); 429 close(inout[1]); 430 close(err[0]); 431 close(err[1]); 432 #endif 433 return -1; 434 case 0: 435 is_child = 1; 436 437 /* 438 * Create a new session and process group since the 4.4BSD 439 * setlogin() affects the entire process group. 440 */ 441 if (setsid() < 0) 442 error("setsid failed: %.100s", strerror(errno)); 443 444 #ifdef USE_PIPES 445 /* 446 * Redirect stdin. We close the parent side of the socket 447 * pair, and make the child side the standard input. 448 */ 449 close(pin[1]); 450 if (dup2(pin[0], 0) < 0) 451 perror("dup2 stdin"); 452 close(pin[0]); 453 454 /* Redirect stdout. */ 455 close(pout[0]); 456 if (dup2(pout[1], 1) < 0) 457 perror("dup2 stdout"); 458 close(pout[1]); 459 460 /* Redirect stderr. */ 461 close(perr[0]); 462 if (dup2(perr[1], 2) < 0) 463 perror("dup2 stderr"); 464 close(perr[1]); 465 #else 466 /* 467 * Redirect stdin, stdout, and stderr. Stdin and stdout will 468 * use the same socket, as some programs (particularly rdist) 469 * seem to depend on it. 470 */ 471 close(inout[1]); 472 close(err[1]); 473 if (dup2(inout[0], 0) < 0) /* stdin */ 474 perror("dup2 stdin"); 475 if (dup2(inout[0], 1) < 0) /* stdout (same as stdin) */ 476 perror("dup2 stdout"); 477 close(inout[0]); 478 if (dup2(err[0], 2) < 0) /* stderr */ 479 perror("dup2 stderr"); 480 close(err[0]); 481 #endif 482 483 /* Do processing for the child (exec command etc). */ 484 do_child(ssh, s, command); 485 /* NOTREACHED */ 486 default: 487 break; 488 } 489 490 #ifdef HAVE_CYGWIN 491 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); 492 #endif 493 494 s->pid = pid; 495 /* Set interactive/non-interactive mode. */ 496 packet_set_interactive(s->display != NULL, 497 options.ip_qos_interactive, options.ip_qos_bulk); 498 499 /* 500 * Clear loginmsg, since it's the child's responsibility to display 501 * it to the user, otherwise multiple sessions may accumulate 502 * multiple copies of the login messages. 503 */ 504 buffer_clear(&loginmsg); 505 506 #ifdef USE_PIPES 507 /* We are the parent. Close the child sides of the pipes. */ 508 close(pin[0]); 509 close(pout[1]); 510 close(perr[1]); 511 512 session_set_fds(ssh, s, pin[1], pout[0], perr[0], 513 s->is_subsystem, 0); 514 #else 515 /* We are the parent. Close the child sides of the socket pairs. */ 516 close(inout[0]); 517 close(err[0]); 518 519 /* 520 * Enter the interactive session. Note: server_loop must be able to 521 * handle the case that fdin and fdout are the same. 522 */ 523 session_set_fds(s, inout[1], inout[1], err[1], 524 s->is_subsystem, 0); 525 #endif 526 return 0; 527 } 528 529 /* 530 * This is called to fork and execute a command when we have a tty. This 531 * will call do_child from the child, and server_loop from the parent after 532 * setting up file descriptors, controlling tty, updating wtmp, utmp, 533 * lastlog, and other such operations. 534 */ 535 int 536 do_exec_pty(struct ssh *ssh, Session *s, const char *command) 537 { 538 int fdout, ptyfd, ttyfd, ptymaster; 539 pid_t pid; 540 541 if (s == NULL) 542 fatal("do_exec_pty: no session"); 543 ptyfd = s->ptyfd; 544 ttyfd = s->ttyfd; 545 546 /* 547 * Create another descriptor of the pty master side for use as the 548 * standard input. We could use the original descriptor, but this 549 * simplifies code in server_loop. The descriptor is bidirectional. 550 * Do this before forking (and cleanup in the child) so as to 551 * detect and gracefully fail out-of-fd conditions. 552 */ 553 if ((fdout = dup(ptyfd)) < 0) { 554 error("%s: dup #1: %s", __func__, strerror(errno)); 555 close(ttyfd); 556 close(ptyfd); 557 return -1; 558 } 559 /* we keep a reference to the pty master */ 560 if ((ptymaster = dup(ptyfd)) < 0) { 561 error("%s: dup #2: %s", __func__, strerror(errno)); 562 close(ttyfd); 563 close(ptyfd); 564 close(fdout); 565 return -1; 566 } 567 568 /* Fork the child. */ 569 switch ((pid = fork())) { 570 case -1: 571 error("%s: fork: %.100s", __func__, strerror(errno)); 572 close(fdout); 573 close(ptymaster); 574 close(ttyfd); 575 close(ptyfd); 576 return -1; 577 case 0: 578 is_child = 1; 579 580 close(fdout); 581 close(ptymaster); 582 583 /* Close the master side of the pseudo tty. */ 584 close(ptyfd); 585 586 /* Make the pseudo tty our controlling tty. */ 587 pty_make_controlling_tty(&ttyfd, s->tty); 588 589 /* Redirect stdin/stdout/stderr from the pseudo tty. */ 590 if (dup2(ttyfd, 0) < 0) 591 error("dup2 stdin: %s", strerror(errno)); 592 if (dup2(ttyfd, 1) < 0) 593 error("dup2 stdout: %s", strerror(errno)); 594 if (dup2(ttyfd, 2) < 0) 595 error("dup2 stderr: %s", strerror(errno)); 596 597 /* Close the extra descriptor for the pseudo tty. */ 598 close(ttyfd); 599 600 /* record login, etc. similar to login(1) */ 601 #ifndef HAVE_OSF_SIA 602 do_login(ssh, s, command); 603 #endif 604 /* 605 * Do common processing for the child, such as execing 606 * the command. 607 */ 608 do_child(ssh, s, command); 609 /* NOTREACHED */ 610 default: 611 break; 612 } 613 614 #ifdef HAVE_CYGWIN 615 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); 616 #endif 617 618 s->pid = pid; 619 620 /* Parent. Close the slave side of the pseudo tty. */ 621 close(ttyfd); 622 623 /* Enter interactive session. */ 624 s->ptymaster = ptymaster; 625 packet_set_interactive(1, 626 options.ip_qos_interactive, options.ip_qos_bulk); 627 session_set_fds(ssh, s, ptyfd, fdout, -1, 1, 1); 628 return 0; 629 } 630 631 #ifdef LOGIN_NEEDS_UTMPX 632 static void 633 do_pre_login(Session *s) 634 { 635 struct ssh *ssh = active_state; /* XXX */ 636 socklen_t fromlen; 637 struct sockaddr_storage from; 638 pid_t pid = getpid(); 639 640 /* 641 * Get IP address of client. If the connection is not a socket, let 642 * the address be 0.0.0.0. 643 */ 644 memset(&from, 0, sizeof(from)); 645 fromlen = sizeof(from); 646 if (packet_connection_is_on_socket()) { 647 if (getpeername(packet_get_connection_in(), 648 (struct sockaddr *)&from, &fromlen) < 0) { 649 debug("getpeername: %.100s", strerror(errno)); 650 cleanup_exit(255); 651 } 652 } 653 654 record_utmp_only(pid, s->tty, s->pw->pw_name, 655 session_get_remote_name_or_ip(ssh, utmp_len, options.use_dns), 656 (struct sockaddr *)&from, fromlen); 657 } 658 #endif 659 660 /* 661 * This is called to fork and execute a command. If another command is 662 * to be forced, execute that instead. 663 */ 664 int 665 do_exec(struct ssh *ssh, Session *s, const char *command) 666 { 667 int ret; 668 const char *forced = NULL, *tty = NULL; 669 char session_type[1024]; 670 671 if (options.adm_forced_command) { 672 original_command = command; 673 command = options.adm_forced_command; 674 forced = "(config)"; 675 } else if (auth_opts->force_command != NULL) { 676 original_command = command; 677 command = auth_opts->force_command; 678 forced = "(key-option)"; 679 } 680 if (forced != NULL) { 681 if (IS_INTERNAL_SFTP(command)) { 682 s->is_subsystem = s->is_subsystem ? 683 SUBSYSTEM_INT_SFTP : SUBSYSTEM_INT_SFTP_ERROR; 684 } else if (s->is_subsystem) 685 s->is_subsystem = SUBSYSTEM_EXT; 686 snprintf(session_type, sizeof(session_type), 687 "forced-command %s '%.900s'", forced, command); 688 } else if (s->is_subsystem) { 689 snprintf(session_type, sizeof(session_type), 690 "subsystem '%.900s'", s->subsys); 691 } else if (command == NULL) { 692 snprintf(session_type, sizeof(session_type), "shell"); 693 } else { 694 /* NB. we don't log unforced commands to preserve privacy */ 695 snprintf(session_type, sizeof(session_type), "command"); 696 } 697 698 if (s->ttyfd != -1) { 699 tty = s->tty; 700 if (strncmp(tty, "/dev/", 5) == 0) 701 tty += 5; 702 } 703 704 verbose("Starting session: %s%s%s for %s from %.200s port %d id %d", 705 session_type, 706 tty == NULL ? "" : " on ", 707 tty == NULL ? "" : tty, 708 s->pw->pw_name, 709 ssh_remote_ipaddr(ssh), 710 ssh_remote_port(ssh), 711 s->self); 712 713 #ifdef SSH_AUDIT_EVENTS 714 if (command != NULL) 715 PRIVSEP(audit_run_command(command)); 716 else if (s->ttyfd == -1) { 717 char *shell = s->pw->pw_shell; 718 719 if (shell[0] == '\0') /* empty shell means /bin/sh */ 720 shell =_PATH_BSHELL; 721 PRIVSEP(audit_run_command(shell)); 722 } 723 #endif 724 if (s->ttyfd != -1) 725 ret = do_exec_pty(ssh, s, command); 726 else 727 ret = do_exec_no_pty(ssh, s, command); 728 729 original_command = NULL; 730 731 /* 732 * Clear loginmsg: it's the child's responsibility to display 733 * it to the user, otherwise multiple sessions may accumulate 734 * multiple copies of the login messages. 735 */ 736 buffer_clear(&loginmsg); 737 738 return ret; 739 } 740 741 /* administrative, login(1)-like work */ 742 void 743 do_login(struct ssh *ssh, Session *s, const char *command) 744 { 745 socklen_t fromlen; 746 struct sockaddr_storage from; 747 struct passwd * pw = s->pw; 748 pid_t pid = getpid(); 749 750 /* 751 * Get IP address of client. If the connection is not a socket, let 752 * the address be 0.0.0.0. 753 */ 754 memset(&from, 0, sizeof(from)); 755 fromlen = sizeof(from); 756 if (packet_connection_is_on_socket()) { 757 if (getpeername(packet_get_connection_in(), 758 (struct sockaddr *)&from, &fromlen) < 0) { 759 debug("getpeername: %.100s", strerror(errno)); 760 cleanup_exit(255); 761 } 762 } 763 764 /* Record that there was a login on that tty from the remote host. */ 765 if (!use_privsep) 766 record_login(pid, s->tty, pw->pw_name, pw->pw_uid, 767 session_get_remote_name_or_ip(ssh, utmp_len, 768 options.use_dns), 769 (struct sockaddr *)&from, fromlen); 770 771 #ifdef USE_PAM 772 /* 773 * If password change is needed, do it now. 774 * This needs to occur before the ~/.hushlogin check. 775 */ 776 if (options.use_pam && !use_privsep && s->authctxt->force_pwchange) { 777 display_loginmsg(); 778 do_pam_chauthtok(); 779 s->authctxt->force_pwchange = 0; 780 /* XXX - signal [net] parent to enable forwardings */ 781 } 782 #endif 783 784 if (check_quietlogin(s, command)) 785 return; 786 787 display_loginmsg(); 788 789 do_motd(); 790 } 791 792 /* 793 * Display the message of the day. 794 */ 795 void 796 do_motd(void) 797 { 798 FILE *f; 799 char buf[256]; 800 801 if (options.print_motd) { 802 #ifdef HAVE_LOGIN_CAP 803 f = fopen(login_getcapstr(lc, "welcome", "/etc/motd", 804 "/etc/motd"), "r"); 805 #else 806 f = fopen("/etc/motd", "r"); 807 #endif 808 if (f) { 809 while (fgets(buf, sizeof(buf), f)) 810 fputs(buf, stdout); 811 fclose(f); 812 } 813 } 814 } 815 816 817 /* 818 * Check for quiet login, either .hushlogin or command given. 819 */ 820 int 821 check_quietlogin(Session *s, const char *command) 822 { 823 char buf[256]; 824 struct passwd *pw = s->pw; 825 struct stat st; 826 827 /* Return 1 if .hushlogin exists or a command given. */ 828 if (command != NULL) 829 return 1; 830 snprintf(buf, sizeof(buf), "%.200s/.hushlogin", pw->pw_dir); 831 #ifdef HAVE_LOGIN_CAP 832 if (login_getcapbool(lc, "hushlogin", 0) || stat(buf, &st) >= 0) 833 return 1; 834 #else 835 if (stat(buf, &st) >= 0) 836 return 1; 837 #endif 838 return 0; 839 } 840 841 /* 842 * Reads environment variables from the given file and adds/overrides them 843 * into the environment. If the file does not exist, this does nothing. 844 * Otherwise, it must consist of empty lines, comments (line starts with '#') 845 * and assignments of the form name=value. No other forms are allowed. 846 */ 847 static void 848 read_environment_file(char ***env, u_int *envsize, 849 const char *filename) 850 { 851 FILE *f; 852 char buf[4096]; 853 char *cp, *value; 854 u_int lineno = 0; 855 856 f = fopen(filename, "r"); 857 if (!f) 858 return; 859 860 while (fgets(buf, sizeof(buf), f)) { 861 if (++lineno > 1000) 862 fatal("Too many lines in environment file %s", filename); 863 for (cp = buf; *cp == ' ' || *cp == '\t'; cp++) 864 ; 865 if (!*cp || *cp == '#' || *cp == '\n') 866 continue; 867 868 cp[strcspn(cp, "\n")] = '\0'; 869 870 value = strchr(cp, '='); 871 if (value == NULL) { 872 fprintf(stderr, "Bad line %u in %.100s\n", lineno, 873 filename); 874 continue; 875 } 876 /* 877 * Replace the equals sign by nul, and advance value to 878 * the value string. 879 */ 880 *value = '\0'; 881 value++; 882 child_set_env(env, envsize, cp, value); 883 } 884 fclose(f); 885 } 886 887 #ifdef HAVE_ETC_DEFAULT_LOGIN 888 /* 889 * Return named variable from specified environment, or NULL if not present. 890 */ 891 static char * 892 child_get_env(char **env, const char *name) 893 { 894 int i; 895 size_t len; 896 897 len = strlen(name); 898 for (i=0; env[i] != NULL; i++) 899 if (strncmp(name, env[i], len) == 0 && env[i][len] == '=') 900 return(env[i] + len + 1); 901 return NULL; 902 } 903 904 /* 905 * Read /etc/default/login. 906 * We pick up the PATH (or SUPATH for root) and UMASK. 907 */ 908 static void 909 read_etc_default_login(char ***env, u_int *envsize, uid_t uid) 910 { 911 char **tmpenv = NULL, *var; 912 u_int i, tmpenvsize = 0; 913 u_long mask; 914 915 /* 916 * We don't want to copy the whole file to the child's environment, 917 * so we use a temporary environment and copy the variables we're 918 * interested in. 919 */ 920 read_environment_file(&tmpenv, &tmpenvsize, "/etc/default/login"); 921 922 if (tmpenv == NULL) 923 return; 924 925 if (uid == 0) 926 var = child_get_env(tmpenv, "SUPATH"); 927 else 928 var = child_get_env(tmpenv, "PATH"); 929 if (var != NULL) 930 child_set_env(env, envsize, "PATH", var); 931 932 if ((var = child_get_env(tmpenv, "UMASK")) != NULL) 933 if (sscanf(var, "%5lo", &mask) == 1) 934 umask((mode_t)mask); 935 936 for (i = 0; tmpenv[i] != NULL; i++) 937 free(tmpenv[i]); 938 free(tmpenv); 939 } 940 #endif /* HAVE_ETC_DEFAULT_LOGIN */ 941 942 static void 943 copy_environment_blacklist(char **source, char ***env, u_int *envsize, 944 const char *blacklist) 945 { 946 char *var_name, *var_val; 947 int i; 948 949 if (source == NULL) 950 return; 951 952 for(i = 0; source[i] != NULL; i++) { 953 var_name = xstrdup(source[i]); 954 if ((var_val = strstr(var_name, "=")) == NULL) { 955 free(var_name); 956 continue; 957 } 958 *var_val++ = '\0'; 959 960 if (blacklist == NULL || 961 match_pattern_list(var_name, blacklist, 0) != 1) { 962 debug3("Copy environment: %s=%s", var_name, var_val); 963 child_set_env(env, envsize, var_name, var_val); 964 } 965 966 free(var_name); 967 } 968 } 969 970 void 971 copy_environment(char **source, char ***env, u_int *envsize) 972 { 973 copy_environment_blacklist(source, env, envsize, NULL); 974 } 975 976 static char ** 977 do_setup_env(struct ssh *ssh, Session *s, const char *shell) 978 { 979 char buf[256]; 980 size_t n; 981 u_int i, envsize; 982 char *ocp, *cp, **env, *laddr; 983 struct passwd *pw = s->pw; 984 #if !defined (HAVE_LOGIN_CAP) && !defined (HAVE_CYGWIN) 985 char *path = NULL; 986 #else 987 extern char **environ; 988 char **senv, **var, *val; 989 #endif 990 991 /* Initialize the environment. */ 992 envsize = 100; 993 env = xcalloc(envsize, sizeof(char *)); 994 env[0] = NULL; 995 996 #ifdef HAVE_CYGWIN 997 /* 998 * The Windows environment contains some setting which are 999 * important for a running system. They must not be dropped. 1000 */ 1001 { 1002 char **p; 1003 1004 p = fetch_windows_environment(); 1005 copy_environment(p, &env, &envsize); 1006 free_windows_environment(p); 1007 } 1008 #endif 1009 1010 if (getenv("TZ")) 1011 child_set_env(&env, &envsize, "TZ", getenv("TZ")); 1012 1013 #ifdef GSSAPI 1014 /* Allow any GSSAPI methods that we've used to alter 1015 * the childs environment as they see fit 1016 */ 1017 ssh_gssapi_do_child(&env, &envsize); 1018 #endif 1019 1020 /* Set basic environment. */ 1021 for (i = 0; i < s->num_env; i++) 1022 child_set_env(&env, &envsize, s->env[i].name, s->env[i].val); 1023 1024 child_set_env(&env, &envsize, "USER", pw->pw_name); 1025 child_set_env(&env, &envsize, "LOGNAME", pw->pw_name); 1026 #ifdef _AIX 1027 child_set_env(&env, &envsize, "LOGIN", pw->pw_name); 1028 #endif 1029 child_set_env(&env, &envsize, "HOME", pw->pw_dir); 1030 snprintf(buf, sizeof buf, "%.200s/%.50s", _PATH_MAILDIR, pw->pw_name); 1031 child_set_env(&env, &envsize, "MAIL", buf); 1032 #ifdef HAVE_LOGIN_CAP 1033 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); 1034 child_set_env(&env, &envsize, "TERM", "su"); 1035 /* 1036 * Temporarily swap out our real environment with an empty one, 1037 * let setusercontext() apply any environment variables defined 1038 * for the user's login class, copy those variables to the child, 1039 * free the temporary environment, and restore the original. 1040 */ 1041 senv = environ; 1042 environ = xmalloc(sizeof(*environ)); 1043 *environ = NULL; 1044 (void)setusercontext(lc, pw, pw->pw_uid, LOGIN_SETENV|LOGIN_SETPATH); 1045 for (var = environ; *var != NULL; ++var) { 1046 if ((val = strchr(*var, '=')) != NULL) { 1047 *val++ = '\0'; 1048 child_set_env(&env, &envsize, *var, val); 1049 } 1050 free(*var); 1051 } 1052 free(environ); 1053 environ = senv; 1054 #else /* HAVE_LOGIN_CAP */ 1055 # ifndef HAVE_CYGWIN 1056 /* 1057 * There's no standard path on Windows. The path contains 1058 * important components pointing to the system directories, 1059 * needed for loading shared libraries. So the path better 1060 * remains intact here. 1061 */ 1062 # ifdef HAVE_ETC_DEFAULT_LOGIN 1063 read_etc_default_login(&env, &envsize, pw->pw_uid); 1064 path = child_get_env(env, "PATH"); 1065 # endif /* HAVE_ETC_DEFAULT_LOGIN */ 1066 if (path == NULL || *path == '\0') { 1067 child_set_env(&env, &envsize, "PATH", 1068 s->pw->pw_uid == 0 ? SUPERUSER_PATH : _PATH_STDPATH); 1069 } 1070 # endif /* HAVE_CYGWIN */ 1071 #endif /* HAVE_LOGIN_CAP */ 1072 1073 /* Normal systems set SHELL by default. */ 1074 child_set_env(&env, &envsize, "SHELL", shell); 1075 1076 1077 /* Set custom environment options from pubkey authentication. */ 1078 if (options.permit_user_env) { 1079 for (n = 0 ; n < auth_opts->nenv; n++) { 1080 ocp = xstrdup(auth_opts->env[n]); 1081 cp = strchr(ocp, '='); 1082 if (*cp == '=') { 1083 *cp = '\0'; 1084 child_set_env(&env, &envsize, ocp, cp + 1); 1085 } 1086 free(ocp); 1087 } 1088 } 1089 1090 /* SSH_CLIENT deprecated */ 1091 snprintf(buf, sizeof buf, "%.50s %d %d", 1092 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 1093 ssh_local_port(ssh)); 1094 child_set_env(&env, &envsize, "SSH_CLIENT", buf); 1095 1096 laddr = get_local_ipaddr(packet_get_connection_in()); 1097 snprintf(buf, sizeof buf, "%.50s %d %.50s %d", 1098 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 1099 laddr, ssh_local_port(ssh)); 1100 free(laddr); 1101 child_set_env(&env, &envsize, "SSH_CONNECTION", buf); 1102 1103 if (tun_fwd_ifnames != NULL) 1104 child_set_env(&env, &envsize, "SSH_TUNNEL", tun_fwd_ifnames); 1105 if (auth_info_file != NULL) 1106 child_set_env(&env, &envsize, "SSH_USER_AUTH", auth_info_file); 1107 if (s->ttyfd != -1) 1108 child_set_env(&env, &envsize, "SSH_TTY", s->tty); 1109 if (s->term) 1110 child_set_env(&env, &envsize, "TERM", s->term); 1111 if (s->display) 1112 child_set_env(&env, &envsize, "DISPLAY", s->display); 1113 if (original_command) 1114 child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND", 1115 original_command); 1116 1117 /* 1118 * Since we clear KRB5CCNAME at startup, if it's set now then it 1119 * must have been set by a native authentication method (eg AIX or 1120 * SIA), so copy it to the child. 1121 */ 1122 { 1123 char *cp; 1124 1125 if ((cp = getenv("KRB5CCNAME")) != NULL) 1126 child_set_env(&env, &envsize, "KRB5CCNAME", cp); 1127 } 1128 1129 #ifdef _AIX 1130 { 1131 char *cp; 1132 1133 if ((cp = getenv("AUTHSTATE")) != NULL) 1134 child_set_env(&env, &envsize, "AUTHSTATE", cp); 1135 read_environment_file(&env, &envsize, "/etc/environment"); 1136 } 1137 #endif 1138 #ifdef KRB5 1139 if (s->authctxt->krb5_ccname) 1140 child_set_env(&env, &envsize, "KRB5CCNAME", 1141 s->authctxt->krb5_ccname); 1142 #endif 1143 #ifdef USE_PAM 1144 /* 1145 * Pull in any environment variables that may have 1146 * been set by PAM. 1147 */ 1148 if (options.use_pam) { 1149 char **p; 1150 1151 /* 1152 * Don't allow SSH_AUTH_INFO variables posted to PAM to leak 1153 * back into the environment. 1154 */ 1155 p = fetch_pam_child_environment(); 1156 copy_environment_blacklist(p, &env, &envsize, "SSH_AUTH_INFO*"); 1157 free_pam_environment(p); 1158 1159 p = fetch_pam_environment(); 1160 copy_environment_blacklist(p, &env, &envsize, "SSH_AUTH_INFO*"); 1161 free_pam_environment(p); 1162 } 1163 #endif /* USE_PAM */ 1164 1165 if (auth_sock_name != NULL) 1166 child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME, 1167 auth_sock_name); 1168 1169 /* read $HOME/.ssh/environment. */ 1170 if (options.permit_user_env) { 1171 snprintf(buf, sizeof buf, "%.200s/.ssh/environment", 1172 strcmp(pw->pw_dir, "/") ? pw->pw_dir : ""); 1173 read_environment_file(&env, &envsize, buf); 1174 } 1175 if (debug_flag) { 1176 /* dump the environment */ 1177 fprintf(stderr, "Environment:\n"); 1178 for (i = 0; env[i]; i++) 1179 fprintf(stderr, " %.200s\n", env[i]); 1180 } 1181 return env; 1182 } 1183 1184 /* 1185 * Run $HOME/.ssh/rc, /etc/ssh/sshrc, or xauth (whichever is found 1186 * first in this order). 1187 */ 1188 static void 1189 do_rc_files(struct ssh *ssh, Session *s, const char *shell) 1190 { 1191 FILE *f = NULL; 1192 char cmd[1024]; 1193 int do_xauth; 1194 struct stat st; 1195 1196 do_xauth = 1197 s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL; 1198 1199 /* ignore _PATH_SSH_USER_RC for subsystems and admin forced commands */ 1200 if (!s->is_subsystem && options.adm_forced_command == NULL && 1201 auth_opts->permit_user_rc && options.permit_user_rc && 1202 stat(_PATH_SSH_USER_RC, &st) >= 0) { 1203 snprintf(cmd, sizeof cmd, "%s -c '%s %s'", 1204 shell, _PATH_BSHELL, _PATH_SSH_USER_RC); 1205 if (debug_flag) 1206 fprintf(stderr, "Running %s\n", cmd); 1207 f = popen(cmd, "w"); 1208 if (f) { 1209 if (do_xauth) 1210 fprintf(f, "%s %s\n", s->auth_proto, 1211 s->auth_data); 1212 pclose(f); 1213 } else 1214 fprintf(stderr, "Could not run %s\n", 1215 _PATH_SSH_USER_RC); 1216 } else if (stat(_PATH_SSH_SYSTEM_RC, &st) >= 0) { 1217 if (debug_flag) 1218 fprintf(stderr, "Running %s %s\n", _PATH_BSHELL, 1219 _PATH_SSH_SYSTEM_RC); 1220 f = popen(_PATH_BSHELL " " _PATH_SSH_SYSTEM_RC, "w"); 1221 if (f) { 1222 if (do_xauth) 1223 fprintf(f, "%s %s\n", s->auth_proto, 1224 s->auth_data); 1225 pclose(f); 1226 } else 1227 fprintf(stderr, "Could not run %s\n", 1228 _PATH_SSH_SYSTEM_RC); 1229 } else if (do_xauth && options.xauth_location != NULL) { 1230 /* Add authority data to .Xauthority if appropriate. */ 1231 if (debug_flag) { 1232 fprintf(stderr, 1233 "Running %.500s remove %.100s\n", 1234 options.xauth_location, s->auth_display); 1235 fprintf(stderr, 1236 "%.500s add %.100s %.100s %.100s\n", 1237 options.xauth_location, s->auth_display, 1238 s->auth_proto, s->auth_data); 1239 } 1240 snprintf(cmd, sizeof cmd, "%s -q -", 1241 options.xauth_location); 1242 f = popen(cmd, "w"); 1243 if (f) { 1244 fprintf(f, "remove %s\n", 1245 s->auth_display); 1246 fprintf(f, "add %s %s %s\n", 1247 s->auth_display, s->auth_proto, 1248 s->auth_data); 1249 pclose(f); 1250 } else { 1251 fprintf(stderr, "Could not run %s\n", 1252 cmd); 1253 } 1254 } 1255 } 1256 1257 static void 1258 do_nologin(struct passwd *pw) 1259 { 1260 FILE *f = NULL; 1261 const char *nl; 1262 char buf[1024], *def_nl = _PATH_NOLOGIN; 1263 struct stat sb; 1264 1265 #ifdef HAVE_LOGIN_CAP 1266 if (login_getcapbool(lc, "ignorenologin", 0) || pw->pw_uid == 0) 1267 return; 1268 nl = login_getcapstr(lc, "nologin", def_nl, def_nl); 1269 #else 1270 if (pw->pw_uid == 0) 1271 return; 1272 nl = def_nl; 1273 #endif 1274 if (stat(nl, &sb) == -1) 1275 return; 1276 1277 /* /etc/nologin exists. Print its contents if we can and exit. */ 1278 logit("User %.100s not allowed because %s exists", pw->pw_name, nl); 1279 if ((f = fopen(nl, "r")) != NULL) { 1280 while (fgets(buf, sizeof(buf), f)) 1281 fputs(buf, stderr); 1282 fclose(f); 1283 } 1284 exit(254); 1285 } 1286 1287 /* 1288 * Chroot into a directory after checking it for safety: all path components 1289 * must be root-owned directories with strict permissions. 1290 */ 1291 static void 1292 safely_chroot(const char *path, uid_t uid) 1293 { 1294 const char *cp; 1295 char component[PATH_MAX]; 1296 struct stat st; 1297 1298 if (*path != '/') 1299 fatal("chroot path does not begin at root"); 1300 if (strlen(path) >= sizeof(component)) 1301 fatal("chroot path too long"); 1302 1303 /* 1304 * Descend the path, checking that each component is a 1305 * root-owned directory with strict permissions. 1306 */ 1307 for (cp = path; cp != NULL;) { 1308 if ((cp = strchr(cp, '/')) == NULL) 1309 strlcpy(component, path, sizeof(component)); 1310 else { 1311 cp++; 1312 memcpy(component, path, cp - path); 1313 component[cp - path] = '\0'; 1314 } 1315 1316 debug3("%s: checking '%s'", __func__, component); 1317 1318 if (stat(component, &st) != 0) 1319 fatal("%s: stat(\"%s\"): %s", __func__, 1320 component, strerror(errno)); 1321 if (st.st_uid != 0 || (st.st_mode & 022) != 0) 1322 fatal("bad ownership or modes for chroot " 1323 "directory %s\"%s\"", 1324 cp == NULL ? "" : "component ", component); 1325 if (!S_ISDIR(st.st_mode)) 1326 fatal("chroot path %s\"%s\" is not a directory", 1327 cp == NULL ? "" : "component ", component); 1328 1329 } 1330 1331 if (chdir(path) == -1) 1332 fatal("Unable to chdir to chroot path \"%s\": " 1333 "%s", path, strerror(errno)); 1334 if (chroot(path) == -1) 1335 fatal("chroot(\"%s\"): %s", path, strerror(errno)); 1336 if (chdir("/") == -1) 1337 fatal("%s: chdir(/) after chroot: %s", 1338 __func__, strerror(errno)); 1339 verbose("Changed root directory to \"%s\"", path); 1340 } 1341 1342 /* Set login name, uid, gid, and groups. */ 1343 void 1344 do_setusercontext(struct passwd *pw) 1345 { 1346 char *chroot_path, *tmp; 1347 1348 platform_setusercontext(pw); 1349 1350 if (platform_privileged_uidswap()) { 1351 #ifdef HAVE_LOGIN_CAP 1352 if (setusercontext(lc, pw, pw->pw_uid, 1353 (LOGIN_SETALL & ~(LOGIN_SETENV|LOGIN_SETPATH|LOGIN_SETUSER))) < 0) { 1354 perror("unable to set user context"); 1355 exit(1); 1356 } 1357 #else 1358 if (setlogin(pw->pw_name) < 0) 1359 error("setlogin failed: %s", strerror(errno)); 1360 if (setgid(pw->pw_gid) < 0) { 1361 perror("setgid"); 1362 exit(1); 1363 } 1364 /* Initialize the group list. */ 1365 if (initgroups(pw->pw_name, pw->pw_gid) < 0) { 1366 perror("initgroups"); 1367 exit(1); 1368 } 1369 endgrent(); 1370 #endif 1371 1372 platform_setusercontext_post_groups(pw); 1373 1374 if (!in_chroot && options.chroot_directory != NULL && 1375 strcasecmp(options.chroot_directory, "none") != 0) { 1376 tmp = tilde_expand_filename(options.chroot_directory, 1377 pw->pw_uid); 1378 chroot_path = percent_expand(tmp, "h", pw->pw_dir, 1379 "u", pw->pw_name, (char *)NULL); 1380 safely_chroot(chroot_path, pw->pw_uid); 1381 free(tmp); 1382 free(chroot_path); 1383 /* Make sure we don't attempt to chroot again */ 1384 free(options.chroot_directory); 1385 options.chroot_directory = NULL; 1386 in_chroot = 1; 1387 } 1388 1389 #ifdef HAVE_LOGIN_CAP 1390 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUSER) < 0) { 1391 perror("unable to set user context (setuser)"); 1392 exit(1); 1393 } 1394 /* 1395 * FreeBSD's setusercontext() will not apply the user's 1396 * own umask setting unless running with the user's UID. 1397 */ 1398 (void) setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUMASK); 1399 #else 1400 # ifdef USE_LIBIAF 1401 /* 1402 * In a chroot environment, the set_id() will always fail; 1403 * typically because of the lack of necessary authentication 1404 * services and runtime such as ./usr/lib/libiaf.so, 1405 * ./usr/lib/libpam.so.1, and ./etc/passwd We skip it in the 1406 * internal sftp chroot case. We'll lose auditing and ACLs but 1407 * permanently_set_uid will take care of the rest. 1408 */ 1409 if (!in_chroot && set_id(pw->pw_name) != 0) 1410 fatal("set_id(%s) Failed", pw->pw_name); 1411 # endif /* USE_LIBIAF */ 1412 /* Permanently switch to the desired uid. */ 1413 permanently_set_uid(pw); 1414 #endif 1415 } else if (options.chroot_directory != NULL && 1416 strcasecmp(options.chroot_directory, "none") != 0) { 1417 fatal("server lacks privileges to chroot to ChrootDirectory"); 1418 } 1419 1420 if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) 1421 fatal("Failed to set uids to %u.", (u_int) pw->pw_uid); 1422 } 1423 1424 static void 1425 do_pwchange(Session *s) 1426 { 1427 fflush(NULL); 1428 fprintf(stderr, "WARNING: Your password has expired.\n"); 1429 if (s->ttyfd != -1) { 1430 fprintf(stderr, 1431 "You must change your password now and login again!\n"); 1432 #ifdef WITH_SELINUX 1433 setexeccon(NULL); 1434 #endif 1435 #ifdef PASSWD_NEEDS_USERNAME 1436 execl(_PATH_PASSWD_PROG, "passwd", s->pw->pw_name, 1437 (char *)NULL); 1438 #else 1439 execl(_PATH_PASSWD_PROG, "passwd", (char *)NULL); 1440 #endif 1441 perror("passwd"); 1442 } else { 1443 fprintf(stderr, 1444 "Password change required but no TTY available.\n"); 1445 } 1446 exit(1); 1447 } 1448 1449 static void 1450 child_close_fds(struct ssh *ssh) 1451 { 1452 extern int auth_sock; 1453 1454 if (auth_sock != -1) { 1455 close(auth_sock); 1456 auth_sock = -1; 1457 } 1458 1459 if (packet_get_connection_in() == packet_get_connection_out()) 1460 close(packet_get_connection_in()); 1461 else { 1462 close(packet_get_connection_in()); 1463 close(packet_get_connection_out()); 1464 } 1465 /* 1466 * Close all descriptors related to channels. They will still remain 1467 * open in the parent. 1468 */ 1469 /* XXX better use close-on-exec? -markus */ 1470 channel_close_all(ssh); 1471 1472 /* 1473 * Close any extra file descriptors. Note that there may still be 1474 * descriptors left by system functions. They will be closed later. 1475 */ 1476 endpwent(); 1477 1478 /* 1479 * Close any extra open file descriptors so that we don't have them 1480 * hanging around in clients. Note that we want to do this after 1481 * initgroups, because at least on Solaris 2.3 it leaves file 1482 * descriptors open. 1483 */ 1484 closefrom(STDERR_FILENO + 1); 1485 } 1486 1487 /* 1488 * Performs common processing for the child, such as setting up the 1489 * environment, closing extra file descriptors, setting the user and group 1490 * ids, and executing the command or shell. 1491 */ 1492 #define ARGV_MAX 10 1493 void 1494 do_child(struct ssh *ssh, Session *s, const char *command) 1495 { 1496 extern char **environ; 1497 char **env; 1498 char *argv[ARGV_MAX]; 1499 const char *shell, *shell0; 1500 struct passwd *pw = s->pw; 1501 int r = 0; 1502 1503 /* remove hostkey from the child's memory */ 1504 destroy_sensitive_data(); 1505 packet_clear_keys(); 1506 1507 /* Force a password change */ 1508 if (s->authctxt->force_pwchange) { 1509 do_setusercontext(pw); 1510 child_close_fds(ssh); 1511 do_pwchange(s); 1512 exit(1); 1513 } 1514 1515 /* 1516 * Login(1) does this as well, and it needs uid 0 for the "-h" 1517 * switch, so we let login(1) to this for us. 1518 */ 1519 #ifdef HAVE_OSF_SIA 1520 session_setup_sia(pw, s->ttyfd == -1 ? NULL : s->tty); 1521 if (!check_quietlogin(s, command)) 1522 do_motd(); 1523 #else /* HAVE_OSF_SIA */ 1524 /* When PAM is enabled we rely on it to do the nologin check */ 1525 if (!options.use_pam) 1526 do_nologin(pw); 1527 do_setusercontext(pw); 1528 /* 1529 * PAM session modules in do_setusercontext may have 1530 * generated messages, so if this in an interactive 1531 * login then display them too. 1532 */ 1533 if (!check_quietlogin(s, command)) 1534 display_loginmsg(); 1535 #endif /* HAVE_OSF_SIA */ 1536 1537 #ifdef USE_PAM 1538 if (options.use_pam && !is_pam_session_open()) { 1539 debug3("PAM session not opened, exiting"); 1540 display_loginmsg(); 1541 exit(254); 1542 } 1543 #endif 1544 1545 /* 1546 * Get the shell from the password data. An empty shell field is 1547 * legal, and means /bin/sh. 1548 */ 1549 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; 1550 1551 /* 1552 * Make sure $SHELL points to the shell from the password file, 1553 * even if shell is overridden from login.conf 1554 */ 1555 env = do_setup_env(ssh, s, shell); 1556 1557 #ifdef HAVE_LOGIN_CAP 1558 shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell); 1559 #endif 1560 1561 /* 1562 * Close the connection descriptors; note that this is the child, and 1563 * the server will still have the socket open, and it is important 1564 * that we do not shutdown it. Note that the descriptors cannot be 1565 * closed before building the environment, as we call 1566 * ssh_remote_ipaddr there. 1567 */ 1568 child_close_fds(ssh); 1569 1570 /* 1571 * Must take new environment into use so that .ssh/rc, 1572 * /etc/ssh/sshrc and xauth are run in the proper environment. 1573 */ 1574 environ = env; 1575 1576 #if defined(KRB5) && defined(USE_AFS) 1577 /* 1578 * At this point, we check to see if AFS is active and if we have 1579 * a valid Kerberos 5 TGT. If so, it seems like a good idea to see 1580 * if we can (and need to) extend the ticket into an AFS token. If 1581 * we don't do this, we run into potential problems if the user's 1582 * home directory is in AFS and it's not world-readable. 1583 */ 1584 1585 if (options.kerberos_get_afs_token && k_hasafs() && 1586 (s->authctxt->krb5_ctx != NULL)) { 1587 char cell[64]; 1588 1589 debug("Getting AFS token"); 1590 1591 k_setpag(); 1592 1593 if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0) 1594 krb5_afslog(s->authctxt->krb5_ctx, 1595 s->authctxt->krb5_fwd_ccache, cell, NULL); 1596 1597 krb5_afslog_home(s->authctxt->krb5_ctx, 1598 s->authctxt->krb5_fwd_ccache, NULL, NULL, pw->pw_dir); 1599 } 1600 #endif 1601 1602 /* Change current directory to the user's home directory. */ 1603 if (chdir(pw->pw_dir) < 0) { 1604 /* Suppress missing homedir warning for chroot case */ 1605 #ifdef HAVE_LOGIN_CAP 1606 r = login_getcapbool(lc, "requirehome", 0); 1607 #endif 1608 if (r || !in_chroot) { 1609 fprintf(stderr, "Could not chdir to home " 1610 "directory %s: %s\n", pw->pw_dir, 1611 strerror(errno)); 1612 } 1613 if (r) 1614 exit(1); 1615 } 1616 1617 closefrom(STDERR_FILENO + 1); 1618 1619 do_rc_files(ssh, s, shell); 1620 1621 /* restore SIGPIPE for child */ 1622 signal(SIGPIPE, SIG_DFL); 1623 1624 if (s->is_subsystem == SUBSYSTEM_INT_SFTP_ERROR) { 1625 printf("This service allows sftp connections only.\n"); 1626 fflush(NULL); 1627 exit(1); 1628 } else if (s->is_subsystem == SUBSYSTEM_INT_SFTP) { 1629 extern int optind, optreset; 1630 int i; 1631 char *p, *args; 1632 1633 setproctitle("%s@%s", s->pw->pw_name, INTERNAL_SFTP_NAME); 1634 args = xstrdup(command ? command : "sftp-server"); 1635 for (i = 0, (p = strtok(args, " ")); p; (p = strtok(NULL, " "))) 1636 if (i < ARGV_MAX - 1) 1637 argv[i++] = p; 1638 argv[i] = NULL; 1639 optind = optreset = 1; 1640 __progname = argv[0]; 1641 #ifdef WITH_SELINUX 1642 ssh_selinux_change_context("sftpd_t"); 1643 #endif 1644 exit(sftp_server_main(i, argv, s->pw)); 1645 } 1646 1647 fflush(NULL); 1648 1649 /* Get the last component of the shell name. */ 1650 if ((shell0 = strrchr(shell, '/')) != NULL) 1651 shell0++; 1652 else 1653 shell0 = shell; 1654 1655 /* 1656 * If we have no command, execute the shell. In this case, the shell 1657 * name to be passed in argv[0] is preceded by '-' to indicate that 1658 * this is a login shell. 1659 */ 1660 if (!command) { 1661 char argv0[256]; 1662 1663 /* Start the shell. Set initial character to '-'. */ 1664 argv0[0] = '-'; 1665 1666 if (strlcpy(argv0 + 1, shell0, sizeof(argv0) - 1) 1667 >= sizeof(argv0) - 1) { 1668 errno = EINVAL; 1669 perror(shell); 1670 exit(1); 1671 } 1672 1673 /* Execute the shell. */ 1674 argv[0] = argv0; 1675 argv[1] = NULL; 1676 execve(shell, argv, env); 1677 1678 /* Executing the shell failed. */ 1679 perror(shell); 1680 exit(1); 1681 } 1682 /* 1683 * Execute the command using the user's shell. This uses the -c 1684 * option to execute the command. 1685 */ 1686 argv[0] = (char *) shell0; 1687 argv[1] = "-c"; 1688 argv[2] = (char *) command; 1689 argv[3] = NULL; 1690 execve(shell, argv, env); 1691 perror(shell); 1692 exit(1); 1693 } 1694 1695 void 1696 session_unused(int id) 1697 { 1698 debug3("%s: session id %d unused", __func__, id); 1699 if (id >= options.max_sessions || 1700 id >= sessions_nalloc) { 1701 fatal("%s: insane session id %d (max %d nalloc %d)", 1702 __func__, id, options.max_sessions, sessions_nalloc); 1703 } 1704 memset(&sessions[id], 0, sizeof(*sessions)); 1705 sessions[id].self = id; 1706 sessions[id].used = 0; 1707 sessions[id].chanid = -1; 1708 sessions[id].ptyfd = -1; 1709 sessions[id].ttyfd = -1; 1710 sessions[id].ptymaster = -1; 1711 sessions[id].x11_chanids = NULL; 1712 sessions[id].next_unused = sessions_first_unused; 1713 sessions_first_unused = id; 1714 } 1715 1716 Session * 1717 session_new(void) 1718 { 1719 Session *s, *tmp; 1720 1721 if (sessions_first_unused == -1) { 1722 if (sessions_nalloc >= options.max_sessions) 1723 return NULL; 1724 debug2("%s: allocate (allocated %d max %d)", 1725 __func__, sessions_nalloc, options.max_sessions); 1726 tmp = xrecallocarray(sessions, sessions_nalloc, 1727 sessions_nalloc + 1, sizeof(*sessions)); 1728 if (tmp == NULL) { 1729 error("%s: cannot allocate %d sessions", 1730 __func__, sessions_nalloc + 1); 1731 return NULL; 1732 } 1733 sessions = tmp; 1734 session_unused(sessions_nalloc++); 1735 } 1736 1737 if (sessions_first_unused >= sessions_nalloc || 1738 sessions_first_unused < 0) { 1739 fatal("%s: insane first_unused %d max %d nalloc %d", 1740 __func__, sessions_first_unused, options.max_sessions, 1741 sessions_nalloc); 1742 } 1743 1744 s = &sessions[sessions_first_unused]; 1745 if (s->used) { 1746 fatal("%s: session %d already used", 1747 __func__, sessions_first_unused); 1748 } 1749 sessions_first_unused = s->next_unused; 1750 s->used = 1; 1751 s->next_unused = -1; 1752 debug("session_new: session %d", s->self); 1753 1754 return s; 1755 } 1756 1757 static void 1758 session_dump(void) 1759 { 1760 int i; 1761 for (i = 0; i < sessions_nalloc; i++) { 1762 Session *s = &sessions[i]; 1763 1764 debug("dump: used %d next_unused %d session %d %p " 1765 "channel %d pid %ld", 1766 s->used, 1767 s->next_unused, 1768 s->self, 1769 s, 1770 s->chanid, 1771 (long)s->pid); 1772 } 1773 } 1774 1775 int 1776 session_open(Authctxt *authctxt, int chanid) 1777 { 1778 Session *s = session_new(); 1779 debug("session_open: channel %d", chanid); 1780 if (s == NULL) { 1781 error("no more sessions"); 1782 return 0; 1783 } 1784 s->authctxt = authctxt; 1785 s->pw = authctxt->pw; 1786 if (s->pw == NULL || !authctxt->valid) 1787 fatal("no user for session %d", s->self); 1788 debug("session_open: session %d: link with channel %d", s->self, chanid); 1789 s->chanid = chanid; 1790 return 1; 1791 } 1792 1793 Session * 1794 session_by_tty(char *tty) 1795 { 1796 int i; 1797 for (i = 0; i < sessions_nalloc; i++) { 1798 Session *s = &sessions[i]; 1799 if (s->used && s->ttyfd != -1 && strcmp(s->tty, tty) == 0) { 1800 debug("session_by_tty: session %d tty %s", i, tty); 1801 return s; 1802 } 1803 } 1804 debug("session_by_tty: unknown tty %.100s", tty); 1805 session_dump(); 1806 return NULL; 1807 } 1808 1809 static Session * 1810 session_by_channel(int id) 1811 { 1812 int i; 1813 for (i = 0; i < sessions_nalloc; i++) { 1814 Session *s = &sessions[i]; 1815 if (s->used && s->chanid == id) { 1816 debug("session_by_channel: session %d channel %d", 1817 i, id); 1818 return s; 1819 } 1820 } 1821 debug("session_by_channel: unknown channel %d", id); 1822 session_dump(); 1823 return NULL; 1824 } 1825 1826 static Session * 1827 session_by_x11_channel(int id) 1828 { 1829 int i, j; 1830 1831 for (i = 0; i < sessions_nalloc; i++) { 1832 Session *s = &sessions[i]; 1833 1834 if (s->x11_chanids == NULL || !s->used) 1835 continue; 1836 for (j = 0; s->x11_chanids[j] != -1; j++) { 1837 if (s->x11_chanids[j] == id) { 1838 debug("session_by_x11_channel: session %d " 1839 "channel %d", s->self, id); 1840 return s; 1841 } 1842 } 1843 } 1844 debug("session_by_x11_channel: unknown channel %d", id); 1845 session_dump(); 1846 return NULL; 1847 } 1848 1849 static Session * 1850 session_by_pid(pid_t pid) 1851 { 1852 int i; 1853 debug("session_by_pid: pid %ld", (long)pid); 1854 for (i = 0; i < sessions_nalloc; i++) { 1855 Session *s = &sessions[i]; 1856 if (s->used && s->pid == pid) 1857 return s; 1858 } 1859 error("session_by_pid: unknown pid %ld", (long)pid); 1860 session_dump(); 1861 return NULL; 1862 } 1863 1864 static int 1865 session_window_change_req(struct ssh *ssh, Session *s) 1866 { 1867 s->col = packet_get_int(); 1868 s->row = packet_get_int(); 1869 s->xpixel = packet_get_int(); 1870 s->ypixel = packet_get_int(); 1871 packet_check_eom(); 1872 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 1873 return 1; 1874 } 1875 1876 static int 1877 session_pty_req(struct ssh *ssh, Session *s) 1878 { 1879 u_int len; 1880 int n_bytes; 1881 1882 if (!auth_opts->permit_pty_flag || !options.permit_tty) { 1883 debug("Allocating a pty not permitted for this connection."); 1884 return 0; 1885 } 1886 if (s->ttyfd != -1) { 1887 packet_disconnect("Protocol error: you already have a pty."); 1888 return 0; 1889 } 1890 1891 s->term = packet_get_string(&len); 1892 s->col = packet_get_int(); 1893 s->row = packet_get_int(); 1894 s->xpixel = packet_get_int(); 1895 s->ypixel = packet_get_int(); 1896 1897 if (strcmp(s->term, "") == 0) { 1898 free(s->term); 1899 s->term = NULL; 1900 } 1901 1902 /* Allocate a pty and open it. */ 1903 debug("Allocating pty."); 1904 if (!PRIVSEP(pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, 1905 sizeof(s->tty)))) { 1906 free(s->term); 1907 s->term = NULL; 1908 s->ptyfd = -1; 1909 s->ttyfd = -1; 1910 error("session_pty_req: session %d alloc failed", s->self); 1911 return 0; 1912 } 1913 debug("session_pty_req: session %d alloc %s", s->self, s->tty); 1914 1915 n_bytes = packet_remaining(); 1916 tty_parse_modes(s->ttyfd, &n_bytes); 1917 1918 if (!use_privsep) 1919 pty_setowner(s->pw, s->tty); 1920 1921 /* Set window size from the packet. */ 1922 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 1923 1924 packet_check_eom(); 1925 session_proctitle(s); 1926 return 1; 1927 } 1928 1929 static int 1930 session_subsystem_req(struct ssh *ssh, Session *s) 1931 { 1932 struct stat st; 1933 u_int len; 1934 int success = 0; 1935 char *prog, *cmd; 1936 u_int i; 1937 1938 s->subsys = packet_get_string(&len); 1939 packet_check_eom(); 1940 debug2("subsystem request for %.100s by user %s", s->subsys, 1941 s->pw->pw_name); 1942 1943 for (i = 0; i < options.num_subsystems; i++) { 1944 if (strcmp(s->subsys, options.subsystem_name[i]) == 0) { 1945 prog = options.subsystem_command[i]; 1946 cmd = options.subsystem_args[i]; 1947 if (strcmp(INTERNAL_SFTP_NAME, prog) == 0) { 1948 s->is_subsystem = SUBSYSTEM_INT_SFTP; 1949 debug("subsystem: %s", prog); 1950 } else { 1951 if (stat(prog, &st) < 0) 1952 debug("subsystem: cannot stat %s: %s", 1953 prog, strerror(errno)); 1954 s->is_subsystem = SUBSYSTEM_EXT; 1955 debug("subsystem: exec() %s", cmd); 1956 } 1957 success = do_exec(ssh, s, cmd) == 0; 1958 break; 1959 } 1960 } 1961 1962 if (!success) 1963 logit("subsystem request for %.100s by user %s failed, " 1964 "subsystem not found", s->subsys, s->pw->pw_name); 1965 1966 return success; 1967 } 1968 1969 static int 1970 session_x11_req(struct ssh *ssh, Session *s) 1971 { 1972 int success; 1973 1974 if (s->auth_proto != NULL || s->auth_data != NULL) { 1975 error("session_x11_req: session %d: " 1976 "x11 forwarding already active", s->self); 1977 return 0; 1978 } 1979 s->single_connection = packet_get_char(); 1980 s->auth_proto = packet_get_string(NULL); 1981 s->auth_data = packet_get_string(NULL); 1982 s->screen = packet_get_int(); 1983 packet_check_eom(); 1984 1985 if (xauth_valid_string(s->auth_proto) && 1986 xauth_valid_string(s->auth_data)) 1987 success = session_setup_x11fwd(ssh, s); 1988 else { 1989 success = 0; 1990 error("Invalid X11 forwarding data"); 1991 } 1992 if (!success) { 1993 free(s->auth_proto); 1994 free(s->auth_data); 1995 s->auth_proto = NULL; 1996 s->auth_data = NULL; 1997 } 1998 return success; 1999 } 2000 2001 static int 2002 session_shell_req(struct ssh *ssh, Session *s) 2003 { 2004 packet_check_eom(); 2005 return do_exec(ssh, s, NULL) == 0; 2006 } 2007 2008 static int 2009 session_exec_req(struct ssh *ssh, Session *s) 2010 { 2011 u_int len, success; 2012 2013 char *command = packet_get_string(&len); 2014 packet_check_eom(); 2015 success = do_exec(ssh, s, command) == 0; 2016 free(command); 2017 return success; 2018 } 2019 2020 static int 2021 session_break_req(struct ssh *ssh, Session *s) 2022 { 2023 2024 packet_get_int(); /* ignored */ 2025 packet_check_eom(); 2026 2027 if (s->ptymaster == -1 || tcsendbreak(s->ptymaster, 0) < 0) 2028 return 0; 2029 return 1; 2030 } 2031 2032 static int 2033 session_env_req(struct ssh *ssh, Session *s) 2034 { 2035 char *name, *val; 2036 u_int name_len, val_len, i; 2037 2038 name = packet_get_cstring(&name_len); 2039 val = packet_get_cstring(&val_len); 2040 packet_check_eom(); 2041 2042 /* Don't set too many environment variables */ 2043 if (s->num_env > 128) { 2044 debug2("Ignoring env request %s: too many env vars", name); 2045 goto fail; 2046 } 2047 2048 for (i = 0; i < options.num_accept_env; i++) { 2049 if (match_pattern(name, options.accept_env[i])) { 2050 debug2("Setting env %d: %s=%s", s->num_env, name, val); 2051 s->env = xrecallocarray(s->env, s->num_env, 2052 s->num_env + 1, sizeof(*s->env)); 2053 s->env[s->num_env].name = name; 2054 s->env[s->num_env].val = val; 2055 s->num_env++; 2056 return (1); 2057 } 2058 } 2059 debug2("Ignoring env request %s: disallowed name", name); 2060 2061 fail: 2062 free(name); 2063 free(val); 2064 return (0); 2065 } 2066 2067 static int 2068 session_auth_agent_req(struct ssh *ssh, Session *s) 2069 { 2070 static int called = 0; 2071 2072 packet_check_eom(); 2073 if (!auth_opts->permit_agent_forwarding_flag || 2074 !options.allow_agent_forwarding) { 2075 debug("%s: agent forwarding disabled", __func__); 2076 return 0; 2077 } 2078 if (called) { 2079 return 0; 2080 } else { 2081 called = 1; 2082 return auth_input_request_forwarding(ssh, s->pw); 2083 } 2084 } 2085 2086 int 2087 session_input_channel_req(struct ssh *ssh, Channel *c, const char *rtype) 2088 { 2089 int success = 0; 2090 Session *s; 2091 2092 if ((s = session_by_channel(c->self)) == NULL) { 2093 logit("%s: no session %d req %.100s", __func__, c->self, rtype); 2094 return 0; 2095 } 2096 debug("%s: session %d req %s", __func__, s->self, rtype); 2097 2098 /* 2099 * a session is in LARVAL state until a shell, a command 2100 * or a subsystem is executed 2101 */ 2102 if (c->type == SSH_CHANNEL_LARVAL) { 2103 if (strcmp(rtype, "shell") == 0) { 2104 success = session_shell_req(ssh, s); 2105 } else if (strcmp(rtype, "exec") == 0) { 2106 success = session_exec_req(ssh, s); 2107 } else if (strcmp(rtype, "pty-req") == 0) { 2108 success = session_pty_req(ssh, s); 2109 } else if (strcmp(rtype, "x11-req") == 0) { 2110 success = session_x11_req(ssh, s); 2111 } else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) { 2112 success = session_auth_agent_req(ssh, s); 2113 } else if (strcmp(rtype, "subsystem") == 0) { 2114 success = session_subsystem_req(ssh, s); 2115 } else if (strcmp(rtype, "env") == 0) { 2116 success = session_env_req(ssh, s); 2117 } 2118 } 2119 if (strcmp(rtype, "window-change") == 0) { 2120 success = session_window_change_req(ssh, s); 2121 } else if (strcmp(rtype, "break") == 0) { 2122 success = session_break_req(ssh, s); 2123 } 2124 2125 return success; 2126 } 2127 2128 void 2129 session_set_fds(struct ssh *ssh, Session *s, 2130 int fdin, int fdout, int fderr, int ignore_fderr, int is_tty) 2131 { 2132 /* 2133 * now that have a child and a pipe to the child, 2134 * we can activate our channel and register the fd's 2135 */ 2136 if (s->chanid == -1) 2137 fatal("no channel for session %d", s->self); 2138 channel_set_fds(ssh, s->chanid, 2139 fdout, fdin, fderr, 2140 ignore_fderr ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ, 2141 1, is_tty, CHAN_SES_WINDOW_DEFAULT); 2142 } 2143 2144 /* 2145 * Function to perform pty cleanup. Also called if we get aborted abnormally 2146 * (e.g., due to a dropped connection). 2147 */ 2148 void 2149 session_pty_cleanup2(Session *s) 2150 { 2151 if (s == NULL) { 2152 error("session_pty_cleanup: no session"); 2153 return; 2154 } 2155 if (s->ttyfd == -1) 2156 return; 2157 2158 debug("session_pty_cleanup: session %d release %s", s->self, s->tty); 2159 2160 /* Record that the user has logged out. */ 2161 if (s->pid != 0) 2162 record_logout(s->pid, s->tty, s->pw->pw_name); 2163 2164 /* Release the pseudo-tty. */ 2165 if (getuid() == 0) 2166 pty_release(s->tty); 2167 2168 /* 2169 * Close the server side of the socket pairs. We must do this after 2170 * the pty cleanup, so that another process doesn't get this pty 2171 * while we're still cleaning up. 2172 */ 2173 if (s->ptymaster != -1 && close(s->ptymaster) < 0) 2174 error("close(s->ptymaster/%d): %s", 2175 s->ptymaster, strerror(errno)); 2176 2177 /* unlink pty from session */ 2178 s->ttyfd = -1; 2179 } 2180 2181 void 2182 session_pty_cleanup(Session *s) 2183 { 2184 PRIVSEP(session_pty_cleanup2(s)); 2185 } 2186 2187 static char * 2188 sig2name(int sig) 2189 { 2190 #define SSH_SIG(x) if (sig == SIG ## x) return #x 2191 SSH_SIG(ABRT); 2192 SSH_SIG(ALRM); 2193 SSH_SIG(FPE); 2194 SSH_SIG(HUP); 2195 SSH_SIG(ILL); 2196 SSH_SIG(INT); 2197 SSH_SIG(KILL); 2198 SSH_SIG(PIPE); 2199 SSH_SIG(QUIT); 2200 SSH_SIG(SEGV); 2201 SSH_SIG(TERM); 2202 SSH_SIG(USR1); 2203 SSH_SIG(USR2); 2204 #undef SSH_SIG 2205 return "SIG@openssh.com"; 2206 } 2207 2208 static void 2209 session_close_x11(struct ssh *ssh, int id) 2210 { 2211 Channel *c; 2212 2213 if ((c = channel_by_id(ssh, id)) == NULL) { 2214 debug("%s: x11 channel %d missing", __func__, id); 2215 } else { 2216 /* Detach X11 listener */ 2217 debug("%s: detach x11 channel %d", __func__, id); 2218 channel_cancel_cleanup(ssh, id); 2219 if (c->ostate != CHAN_OUTPUT_CLOSED) 2220 chan_mark_dead(ssh, c); 2221 } 2222 } 2223 2224 static void 2225 session_close_single_x11(struct ssh *ssh, int id, void *arg) 2226 { 2227 Session *s; 2228 u_int i; 2229 2230 debug3("%s: channel %d", __func__, id); 2231 channel_cancel_cleanup(ssh, id); 2232 if ((s = session_by_x11_channel(id)) == NULL) 2233 fatal("%s: no x11 channel %d", __func__, id); 2234 for (i = 0; s->x11_chanids[i] != -1; i++) { 2235 debug("%s: session %d: closing channel %d", 2236 __func__, s->self, s->x11_chanids[i]); 2237 /* 2238 * The channel "id" is already closing, but make sure we 2239 * close all of its siblings. 2240 */ 2241 if (s->x11_chanids[i] != id) 2242 session_close_x11(ssh, s->x11_chanids[i]); 2243 } 2244 free(s->x11_chanids); 2245 s->x11_chanids = NULL; 2246 free(s->display); 2247 s->display = NULL; 2248 free(s->auth_proto); 2249 s->auth_proto = NULL; 2250 free(s->auth_data); 2251 s->auth_data = NULL; 2252 free(s->auth_display); 2253 s->auth_display = NULL; 2254 } 2255 2256 static void 2257 session_exit_message(struct ssh *ssh, Session *s, int status) 2258 { 2259 Channel *c; 2260 2261 if ((c = channel_lookup(ssh, s->chanid)) == NULL) 2262 fatal("%s: session %d: no channel %d", 2263 __func__, s->self, s->chanid); 2264 debug("%s: session %d channel %d pid %ld", 2265 __func__, s->self, s->chanid, (long)s->pid); 2266 2267 if (WIFEXITED(status)) { 2268 channel_request_start(ssh, s->chanid, "exit-status", 0); 2269 packet_put_int(WEXITSTATUS(status)); 2270 packet_send(); 2271 } else if (WIFSIGNALED(status)) { 2272 channel_request_start(ssh, s->chanid, "exit-signal", 0); 2273 packet_put_cstring(sig2name(WTERMSIG(status))); 2274 #ifdef WCOREDUMP 2275 packet_put_char(WCOREDUMP(status)? 1 : 0); 2276 #else /* WCOREDUMP */ 2277 packet_put_char(0); 2278 #endif /* WCOREDUMP */ 2279 packet_put_cstring(""); 2280 packet_put_cstring(""); 2281 packet_send(); 2282 } else { 2283 /* Some weird exit cause. Just exit. */ 2284 packet_disconnect("wait returned status %04x.", status); 2285 } 2286 2287 /* disconnect channel */ 2288 debug("%s: release channel %d", __func__, s->chanid); 2289 2290 /* 2291 * Adjust cleanup callback attachment to send close messages when 2292 * the channel gets EOF. The session will be then be closed 2293 * by session_close_by_channel when the childs close their fds. 2294 */ 2295 channel_register_cleanup(ssh, c->self, session_close_by_channel, 1); 2296 2297 /* 2298 * emulate a write failure with 'chan_write_failed', nobody will be 2299 * interested in data we write. 2300 * Note that we must not call 'chan_read_failed', since there could 2301 * be some more data waiting in the pipe. 2302 */ 2303 if (c->ostate != CHAN_OUTPUT_CLOSED) 2304 chan_write_failed(ssh, c); 2305 } 2306 2307 void 2308 session_close(struct ssh *ssh, Session *s) 2309 { 2310 u_int i; 2311 2312 verbose("Close session: user %s from %.200s port %d id %d", 2313 s->pw->pw_name, 2314 ssh_remote_ipaddr(ssh), 2315 ssh_remote_port(ssh), 2316 s->self); 2317 2318 if (s->ttyfd != -1) 2319 session_pty_cleanup(s); 2320 free(s->term); 2321 free(s->display); 2322 free(s->x11_chanids); 2323 free(s->auth_display); 2324 free(s->auth_data); 2325 free(s->auth_proto); 2326 free(s->subsys); 2327 if (s->env != NULL) { 2328 for (i = 0; i < s->num_env; i++) { 2329 free(s->env[i].name); 2330 free(s->env[i].val); 2331 } 2332 free(s->env); 2333 } 2334 session_proctitle(s); 2335 session_unused(s->self); 2336 } 2337 2338 void 2339 session_close_by_pid(struct ssh *ssh, pid_t pid, int status) 2340 { 2341 Session *s = session_by_pid(pid); 2342 if (s == NULL) { 2343 debug("%s: no session for pid %ld", __func__, (long)pid); 2344 return; 2345 } 2346 if (s->chanid != -1) 2347 session_exit_message(ssh, s, status); 2348 if (s->ttyfd != -1) 2349 session_pty_cleanup(s); 2350 s->pid = 0; 2351 } 2352 2353 /* 2354 * this is called when a channel dies before 2355 * the session 'child' itself dies 2356 */ 2357 void 2358 session_close_by_channel(struct ssh *ssh, int id, void *arg) 2359 { 2360 Session *s = session_by_channel(id); 2361 u_int i; 2362 2363 if (s == NULL) { 2364 debug("%s: no session for id %d", __func__, id); 2365 return; 2366 } 2367 debug("%s: channel %d child %ld", __func__, id, (long)s->pid); 2368 if (s->pid != 0) { 2369 debug("%s: channel %d: has child", __func__, id); 2370 /* 2371 * delay detach of session, but release pty, since 2372 * the fd's to the child are already closed 2373 */ 2374 if (s->ttyfd != -1) 2375 session_pty_cleanup(s); 2376 return; 2377 } 2378 /* detach by removing callback */ 2379 channel_cancel_cleanup(ssh, s->chanid); 2380 2381 /* Close any X11 listeners associated with this session */ 2382 if (s->x11_chanids != NULL) { 2383 for (i = 0; s->x11_chanids[i] != -1; i++) { 2384 session_close_x11(ssh, s->x11_chanids[i]); 2385 s->x11_chanids[i] = -1; 2386 } 2387 } 2388 2389 s->chanid = -1; 2390 session_close(ssh, s); 2391 } 2392 2393 void 2394 session_destroy_all(struct ssh *ssh, void (*closefunc)(Session *)) 2395 { 2396 int i; 2397 for (i = 0; i < sessions_nalloc; i++) { 2398 Session *s = &sessions[i]; 2399 if (s->used) { 2400 if (closefunc != NULL) 2401 closefunc(s); 2402 else 2403 session_close(ssh, s); 2404 } 2405 } 2406 } 2407 2408 static char * 2409 session_tty_list(void) 2410 { 2411 static char buf[1024]; 2412 int i; 2413 char *cp; 2414 2415 buf[0] = '\0'; 2416 for (i = 0; i < sessions_nalloc; i++) { 2417 Session *s = &sessions[i]; 2418 if (s->used && s->ttyfd != -1) { 2419 2420 if (strncmp(s->tty, "/dev/", 5) != 0) { 2421 cp = strrchr(s->tty, '/'); 2422 cp = (cp == NULL) ? s->tty : cp + 1; 2423 } else 2424 cp = s->tty + 5; 2425 2426 if (buf[0] != '\0') 2427 strlcat(buf, ",", sizeof buf); 2428 strlcat(buf, cp, sizeof buf); 2429 } 2430 } 2431 if (buf[0] == '\0') 2432 strlcpy(buf, "notty", sizeof buf); 2433 return buf; 2434 } 2435 2436 void 2437 session_proctitle(Session *s) 2438 { 2439 if (s->pw == NULL) 2440 error("no user for session %d", s->self); 2441 else 2442 setproctitle("%s@%s", s->pw->pw_name, session_tty_list()); 2443 } 2444 2445 int 2446 session_setup_x11fwd(struct ssh *ssh, Session *s) 2447 { 2448 struct stat st; 2449 char display[512], auth_display[512]; 2450 char hostname[NI_MAXHOST]; 2451 u_int i; 2452 2453 if (!auth_opts->permit_x11_forwarding_flag) { 2454 packet_send_debug("X11 forwarding disabled by key options."); 2455 return 0; 2456 } 2457 if (!options.x11_forwarding) { 2458 debug("X11 forwarding disabled in server configuration file."); 2459 return 0; 2460 } 2461 if (options.xauth_location == NULL || 2462 (stat(options.xauth_location, &st) == -1)) { 2463 packet_send_debug("No xauth program; cannot forward X11."); 2464 return 0; 2465 } 2466 if (s->display != NULL) { 2467 debug("X11 display already set."); 2468 return 0; 2469 } 2470 if (x11_create_display_inet(ssh, options.x11_display_offset, 2471 options.x11_use_localhost, s->single_connection, 2472 &s->display_number, &s->x11_chanids) == -1) { 2473 debug("x11_create_display_inet failed."); 2474 return 0; 2475 } 2476 for (i = 0; s->x11_chanids[i] != -1; i++) { 2477 channel_register_cleanup(ssh, s->x11_chanids[i], 2478 session_close_single_x11, 0); 2479 } 2480 2481 /* Set up a suitable value for the DISPLAY variable. */ 2482 if (gethostname(hostname, sizeof(hostname)) < 0) 2483 fatal("gethostname: %.100s", strerror(errno)); 2484 /* 2485 * auth_display must be used as the displayname when the 2486 * authorization entry is added with xauth(1). This will be 2487 * different than the DISPLAY string for localhost displays. 2488 */ 2489 if (options.x11_use_localhost) { 2490 snprintf(display, sizeof display, "localhost:%u.%u", 2491 s->display_number, s->screen); 2492 snprintf(auth_display, sizeof auth_display, "unix:%u.%u", 2493 s->display_number, s->screen); 2494 s->display = xstrdup(display); 2495 s->auth_display = xstrdup(auth_display); 2496 } else { 2497 #ifdef IPADDR_IN_DISPLAY 2498 struct hostent *he; 2499 struct in_addr my_addr; 2500 2501 he = gethostbyname(hostname); 2502 if (he == NULL) { 2503 error("Can't get IP address for X11 DISPLAY."); 2504 packet_send_debug("Can't get IP address for X11 DISPLAY."); 2505 return 0; 2506 } 2507 memcpy(&my_addr, he->h_addr_list[0], sizeof(struct in_addr)); 2508 snprintf(display, sizeof display, "%.50s:%u.%u", inet_ntoa(my_addr), 2509 s->display_number, s->screen); 2510 #else 2511 snprintf(display, sizeof display, "%.400s:%u.%u", hostname, 2512 s->display_number, s->screen); 2513 #endif 2514 s->display = xstrdup(display); 2515 s->auth_display = xstrdup(display); 2516 } 2517 2518 return 1; 2519 } 2520 2521 static void 2522 do_authenticated2(struct ssh *ssh, Authctxt *authctxt) 2523 { 2524 server_loop2(ssh, authctxt); 2525 } 2526 2527 void 2528 do_cleanup(struct ssh *ssh, Authctxt *authctxt) 2529 { 2530 static int called = 0; 2531 2532 debug("do_cleanup"); 2533 2534 /* no cleanup if we're in the child for login shell */ 2535 if (is_child) 2536 return; 2537 2538 /* avoid double cleanup */ 2539 if (called) 2540 return; 2541 called = 1; 2542 2543 if (authctxt == NULL) 2544 return; 2545 2546 #ifdef USE_PAM 2547 if (options.use_pam) { 2548 sshpam_cleanup(); 2549 sshpam_thread_cleanup(); 2550 } 2551 #endif 2552 2553 if (!authctxt->authenticated) 2554 return; 2555 2556 #ifdef KRB5 2557 if (options.kerberos_ticket_cleanup && 2558 authctxt->krb5_ctx) 2559 krb5_cleanup_proc(authctxt); 2560 #endif 2561 2562 #ifdef GSSAPI 2563 if (options.gss_cleanup_creds) 2564 ssh_gssapi_cleanup_creds(); 2565 #endif 2566 2567 /* remove agent socket */ 2568 auth_sock_cleanup_proc(authctxt->pw); 2569 2570 /* remove userauth info */ 2571 if (auth_info_file != NULL) { 2572 temporarily_use_uid(authctxt->pw); 2573 unlink(auth_info_file); 2574 restore_uid(); 2575 free(auth_info_file); 2576 auth_info_file = NULL; 2577 } 2578 2579 /* 2580 * Cleanup ptys/utmp only if privsep is disabled, 2581 * or if running in monitor. 2582 */ 2583 if (!use_privsep || mm_is_monitor()) 2584 session_destroy_all(ssh, session_pty_cleanup2); 2585 } 2586 2587 /* Return a name for the remote host that fits inside utmp_size */ 2588 2589 const char * 2590 session_get_remote_name_or_ip(struct ssh *ssh, u_int utmp_size, int use_dns) 2591 { 2592 const char *remote = ""; 2593 2594 if (utmp_size > 0) 2595 remote = auth_get_canonical_hostname(ssh, use_dns); 2596 if (utmp_size == 0 || strlen(remote) > utmp_size) 2597 remote = ssh_remote_ipaddr(ssh); 2598 return remote; 2599 } 2600 2601