1 /* $OpenBSD: session.c,v 1.305 2018/07/25 13:56:23 deraadt 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 "sshbuf.h" 74 #include "ssherr.h" 75 #include "match.h" 76 #include "uidswap.h" 77 #include "compat.h" 78 #include "channels.h" 79 #include "sshkey.h" 80 #include "cipher.h" 81 #ifdef GSSAPI 82 #include "ssh-gss.h" 83 #endif 84 #include "hostfile.h" 85 #include "auth.h" 86 #include "auth-options.h" 87 #include "authfd.h" 88 #include "pathnames.h" 89 #include "log.h" 90 #include "misc.h" 91 #include "servconf.h" 92 #include "sshlogin.h" 93 #include "serverloop.h" 94 #include "canohost.h" 95 #include "session.h" 96 #include "kex.h" 97 #include "monitor_wrap.h" 98 #include "sftp.h" 99 #include "atomicio.h" 100 101 #if defined(KRB5) && defined(USE_AFS) 102 #include <kafs.h> 103 #endif 104 105 #ifdef WITH_SELINUX 106 #include <selinux/selinux.h> 107 #endif 108 109 #define IS_INTERNAL_SFTP(c) \ 110 (!strncmp(c, INTERNAL_SFTP_NAME, sizeof(INTERNAL_SFTP_NAME) - 1) && \ 111 (c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\0' || \ 112 c[sizeof(INTERNAL_SFTP_NAME) - 1] == ' ' || \ 113 c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\t')) 114 115 /* func */ 116 117 Session *session_new(void); 118 void session_set_fds(struct ssh *, Session *, int, int, int, int, int); 119 void session_pty_cleanup(Session *); 120 void session_proctitle(Session *); 121 int session_setup_x11fwd(struct ssh *, Session *); 122 int do_exec_pty(struct ssh *, Session *, const char *); 123 int do_exec_no_pty(struct ssh *, Session *, const char *); 124 int do_exec(struct ssh *, Session *, const char *); 125 void do_login(struct ssh *, Session *, const char *); 126 void do_child(struct ssh *, Session *, const char *); 127 #ifdef LOGIN_NEEDS_UTMPX 128 static void do_pre_login(Session *s); 129 #endif 130 void do_motd(void); 131 int check_quietlogin(Session *, const char *); 132 133 static void do_authenticated2(struct ssh *, Authctxt *); 134 135 static int session_pty_req(struct ssh *, Session *); 136 137 /* import */ 138 extern ServerOptions options; 139 extern char *__progname; 140 extern int debug_flag; 141 extern u_int utmp_len; 142 extern int startup_pipe; 143 extern void destroy_sensitive_data(void); 144 extern struct sshbuf *loginmsg; 145 extern struct sshauthopt *auth_opts; 146 char *tun_fwd_ifnames; /* serverloop.c */ 147 148 /* original command from peer. */ 149 const char *original_command = NULL; 150 151 /* data */ 152 static int sessions_first_unused = -1; 153 static int sessions_nalloc = 0; 154 static Session *sessions = NULL; 155 156 #define SUBSYSTEM_NONE 0 157 #define SUBSYSTEM_EXT 1 158 #define SUBSYSTEM_INT_SFTP 2 159 #define SUBSYSTEM_INT_SFTP_ERROR 3 160 161 #ifdef HAVE_LOGIN_CAP 162 login_cap_t *lc; 163 #endif 164 165 static int is_child = 0; 166 static int in_chroot = 0; 167 168 /* File containing userauth info, if ExposeAuthInfo set */ 169 static char *auth_info_file = NULL; 170 171 /* Name and directory of socket for authentication agent forwarding. */ 172 static char *auth_sock_name = NULL; 173 static char *auth_sock_dir = NULL; 174 175 /* removes the agent forwarding socket */ 176 177 static void 178 auth_sock_cleanup_proc(struct passwd *pw) 179 { 180 if (auth_sock_name != NULL) { 181 temporarily_use_uid(pw); 182 unlink(auth_sock_name); 183 rmdir(auth_sock_dir); 184 auth_sock_name = NULL; 185 restore_uid(); 186 } 187 } 188 189 static int 190 auth_input_request_forwarding(struct ssh *ssh, struct passwd * pw) 191 { 192 Channel *nc; 193 int sock = -1; 194 195 if (auth_sock_name != NULL) { 196 error("authentication forwarding requested twice."); 197 return 0; 198 } 199 200 /* Temporarily drop privileged uid for mkdir/bind. */ 201 temporarily_use_uid(pw); 202 203 /* Allocate a buffer for the socket name, and format the name. */ 204 auth_sock_dir = xstrdup("/tmp/ssh-XXXXXXXXXX"); 205 206 /* Create private directory for socket */ 207 if (mkdtemp(auth_sock_dir) == NULL) { 208 packet_send_debug("Agent forwarding disabled: " 209 "mkdtemp() failed: %.100s", strerror(errno)); 210 restore_uid(); 211 free(auth_sock_dir); 212 auth_sock_dir = NULL; 213 goto authsock_err; 214 } 215 216 xasprintf(&auth_sock_name, "%s/agent.%ld", 217 auth_sock_dir, (long) getpid()); 218 219 /* Start a Unix listener on auth_sock_name. */ 220 sock = unix_listener(auth_sock_name, SSH_LISTEN_BACKLOG, 0); 221 222 /* Restore the privileged uid. */ 223 restore_uid(); 224 225 /* Check for socket/bind/listen failure. */ 226 if (sock < 0) 227 goto authsock_err; 228 229 /* Allocate a channel for the authentication agent socket. */ 230 nc = channel_new(ssh, "auth socket", 231 SSH_CHANNEL_AUTH_SOCKET, sock, sock, -1, 232 CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 233 0, "auth socket", 1); 234 nc->path = xstrdup(auth_sock_name); 235 return 1; 236 237 authsock_err: 238 free(auth_sock_name); 239 if (auth_sock_dir != NULL) { 240 rmdir(auth_sock_dir); 241 free(auth_sock_dir); 242 } 243 if (sock != -1) 244 close(sock); 245 auth_sock_name = NULL; 246 auth_sock_dir = NULL; 247 return 0; 248 } 249 250 static void 251 display_loginmsg(void) 252 { 253 int r; 254 255 if (sshbuf_len(loginmsg) == 0) 256 return; 257 if ((r = sshbuf_put_u8(loginmsg, 0)) != 0) 258 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 259 printf("%s", (char *)sshbuf_ptr(loginmsg)); 260 sshbuf_reset(loginmsg); 261 } 262 263 static void 264 prepare_auth_info_file(struct passwd *pw, struct sshbuf *info) 265 { 266 int fd = -1, success = 0; 267 268 if (!options.expose_userauth_info || info == NULL) 269 return; 270 271 temporarily_use_uid(pw); 272 auth_info_file = xstrdup("/tmp/sshauth.XXXXXXXXXXXXXXX"); 273 if ((fd = mkstemp(auth_info_file)) == -1) { 274 error("%s: mkstemp: %s", __func__, strerror(errno)); 275 goto out; 276 } 277 if (atomicio(vwrite, fd, sshbuf_mutable_ptr(info), 278 sshbuf_len(info)) != sshbuf_len(info)) { 279 error("%s: write: %s", __func__, strerror(errno)); 280 goto out; 281 } 282 if (close(fd) != 0) { 283 error("%s: close: %s", __func__, strerror(errno)); 284 goto out; 285 } 286 success = 1; 287 out: 288 if (!success) { 289 if (fd != -1) 290 close(fd); 291 free(auth_info_file); 292 auth_info_file = NULL; 293 } 294 restore_uid(); 295 } 296 297 static void 298 set_fwdpermit_from_authopts(struct ssh *ssh, const struct sshauthopt *opts) 299 { 300 char *tmp, *cp, *host; 301 int port; 302 size_t i; 303 304 if ((options.allow_tcp_forwarding & FORWARD_LOCAL) != 0) { 305 channel_clear_permission(ssh, FORWARD_USER, FORWARD_LOCAL); 306 for (i = 0; i < auth_opts->npermitopen; i++) { 307 tmp = cp = xstrdup(auth_opts->permitopen[i]); 308 /* This shouldn't fail as it has already been checked */ 309 if ((host = hpdelim(&cp)) == NULL) 310 fatal("%s: internal error: hpdelim", __func__); 311 host = cleanhostname(host); 312 if (cp == NULL || (port = permitopen_port(cp)) < 0) 313 fatal("%s: internal error: permitopen port", 314 __func__); 315 channel_add_permission(ssh, 316 FORWARD_USER, FORWARD_LOCAL, host, port); 317 free(tmp); 318 } 319 } 320 if ((options.allow_tcp_forwarding & FORWARD_REMOTE) != 0) { 321 channel_clear_permission(ssh, FORWARD_USER, FORWARD_REMOTE); 322 for (i = 0; i < auth_opts->npermitlisten; i++) { 323 tmp = cp = xstrdup(auth_opts->permitlisten[i]); 324 /* This shouldn't fail as it has already been checked */ 325 if ((host = hpdelim(&cp)) == NULL) 326 fatal("%s: internal error: hpdelim", __func__); 327 host = cleanhostname(host); 328 if (cp == NULL || (port = permitopen_port(cp)) < 0) 329 fatal("%s: internal error: permitlisten port", 330 __func__); 331 channel_add_permission(ssh, 332 FORWARD_USER, FORWARD_REMOTE, host, port); 333 free(tmp); 334 } 335 } 336 } 337 338 void 339 do_authenticated(struct ssh *ssh, Authctxt *authctxt) 340 { 341 setproctitle("%s", authctxt->pw->pw_name); 342 343 auth_log_authopts("active", auth_opts, 0); 344 345 /* setup the channel layer */ 346 /* XXX - streamlocal? */ 347 set_fwdpermit_from_authopts(ssh, auth_opts); 348 349 if (!auth_opts->permit_port_forwarding_flag || 350 options.disable_forwarding) { 351 channel_disable_admin(ssh, FORWARD_LOCAL); 352 channel_disable_admin(ssh, FORWARD_REMOTE); 353 } else { 354 if ((options.allow_tcp_forwarding & FORWARD_LOCAL) == 0) 355 channel_disable_admin(ssh, FORWARD_LOCAL); 356 else 357 channel_permit_all(ssh, FORWARD_LOCAL); 358 if ((options.allow_tcp_forwarding & FORWARD_REMOTE) == 0) 359 channel_disable_admin(ssh, FORWARD_REMOTE); 360 else 361 channel_permit_all(ssh, FORWARD_REMOTE); 362 } 363 auth_debug_send(); 364 365 prepare_auth_info_file(authctxt->pw, authctxt->session_info); 366 367 do_authenticated2(ssh, authctxt); 368 369 do_cleanup(ssh, authctxt); 370 } 371 372 /* Check untrusted xauth strings for metacharacters */ 373 static int 374 xauth_valid_string(const char *s) 375 { 376 size_t i; 377 378 for (i = 0; s[i] != '\0'; i++) { 379 if (!isalnum((u_char)s[i]) && 380 s[i] != '.' && s[i] != ':' && s[i] != '/' && 381 s[i] != '-' && s[i] != '_') 382 return 0; 383 } 384 return 1; 385 } 386 387 #define USE_PIPES 1 388 /* 389 * This is called to fork and execute a command when we have no tty. This 390 * will call do_child from the child, and server_loop from the parent after 391 * setting up file descriptors and such. 392 */ 393 int 394 do_exec_no_pty(struct ssh *ssh, Session *s, const char *command) 395 { 396 pid_t pid; 397 #ifdef USE_PIPES 398 int pin[2], pout[2], perr[2]; 399 400 if (s == NULL) 401 fatal("do_exec_no_pty: no session"); 402 403 /* Allocate pipes for communicating with the program. */ 404 if (pipe(pin) < 0) { 405 error("%s: pipe in: %.100s", __func__, strerror(errno)); 406 return -1; 407 } 408 if (pipe(pout) < 0) { 409 error("%s: pipe out: %.100s", __func__, strerror(errno)); 410 close(pin[0]); 411 close(pin[1]); 412 return -1; 413 } 414 if (pipe(perr) < 0) { 415 error("%s: pipe err: %.100s", __func__, 416 strerror(errno)); 417 close(pin[0]); 418 close(pin[1]); 419 close(pout[0]); 420 close(pout[1]); 421 return -1; 422 } 423 #else 424 int inout[2], err[2]; 425 426 if (s == NULL) 427 fatal("do_exec_no_pty: no session"); 428 429 /* Uses socket pairs to communicate with the program. */ 430 if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) < 0) { 431 error("%s: socketpair #1: %.100s", __func__, strerror(errno)); 432 return -1; 433 } 434 if (socketpair(AF_UNIX, SOCK_STREAM, 0, err) < 0) { 435 error("%s: socketpair #2: %.100s", __func__, 436 strerror(errno)); 437 close(inout[0]); 438 close(inout[1]); 439 return -1; 440 } 441 #endif 442 443 session_proctitle(s); 444 445 /* Fork the child. */ 446 switch ((pid = fork())) { 447 case -1: 448 error("%s: fork: %.100s", __func__, strerror(errno)); 449 #ifdef USE_PIPES 450 close(pin[0]); 451 close(pin[1]); 452 close(pout[0]); 453 close(pout[1]); 454 close(perr[0]); 455 close(perr[1]); 456 #else 457 close(inout[0]); 458 close(inout[1]); 459 close(err[0]); 460 close(err[1]); 461 #endif 462 return -1; 463 case 0: 464 is_child = 1; 465 466 /* 467 * Create a new session and process group since the 4.4BSD 468 * setlogin() affects the entire process group. 469 */ 470 if (setsid() < 0) 471 error("setsid failed: %.100s", strerror(errno)); 472 473 #ifdef USE_PIPES 474 /* 475 * Redirect stdin. We close the parent side of the socket 476 * pair, and make the child side the standard input. 477 */ 478 close(pin[1]); 479 if (dup2(pin[0], 0) < 0) 480 perror("dup2 stdin"); 481 close(pin[0]); 482 483 /* Redirect stdout. */ 484 close(pout[0]); 485 if (dup2(pout[1], 1) < 0) 486 perror("dup2 stdout"); 487 close(pout[1]); 488 489 /* Redirect stderr. */ 490 close(perr[0]); 491 if (dup2(perr[1], 2) < 0) 492 perror("dup2 stderr"); 493 close(perr[1]); 494 #else 495 /* 496 * Redirect stdin, stdout, and stderr. Stdin and stdout will 497 * use the same socket, as some programs (particularly rdist) 498 * seem to depend on it. 499 */ 500 close(inout[1]); 501 close(err[1]); 502 if (dup2(inout[0], 0) < 0) /* stdin */ 503 perror("dup2 stdin"); 504 if (dup2(inout[0], 1) < 0) /* stdout (same as stdin) */ 505 perror("dup2 stdout"); 506 close(inout[0]); 507 if (dup2(err[0], 2) < 0) /* stderr */ 508 perror("dup2 stderr"); 509 close(err[0]); 510 #endif 511 512 /* Do processing for the child (exec command etc). */ 513 do_child(ssh, s, command); 514 /* NOTREACHED */ 515 default: 516 break; 517 } 518 519 #ifdef HAVE_CYGWIN 520 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); 521 #endif 522 523 s->pid = pid; 524 /* Set interactive/non-interactive mode. */ 525 packet_set_interactive(s->display != NULL, 526 options.ip_qos_interactive, options.ip_qos_bulk); 527 528 /* 529 * Clear loginmsg, since it's the child's responsibility to display 530 * it to the user, otherwise multiple sessions may accumulate 531 * multiple copies of the login messages. 532 */ 533 sshbuf_reset(loginmsg); 534 535 #ifdef USE_PIPES 536 /* We are the parent. Close the child sides of the pipes. */ 537 close(pin[0]); 538 close(pout[1]); 539 close(perr[1]); 540 541 session_set_fds(ssh, s, pin[1], pout[0], perr[0], 542 s->is_subsystem, 0); 543 #else 544 /* We are the parent. Close the child sides of the socket pairs. */ 545 close(inout[0]); 546 close(err[0]); 547 548 /* 549 * Enter the interactive session. Note: server_loop must be able to 550 * handle the case that fdin and fdout are the same. 551 */ 552 session_set_fds(s, inout[1], inout[1], err[1], 553 s->is_subsystem, 0); 554 #endif 555 return 0; 556 } 557 558 /* 559 * This is called to fork and execute a command when we have a tty. This 560 * will call do_child from the child, and server_loop from the parent after 561 * setting up file descriptors, controlling tty, updating wtmp, utmp, 562 * lastlog, and other such operations. 563 */ 564 int 565 do_exec_pty(struct ssh *ssh, Session *s, const char *command) 566 { 567 int fdout, ptyfd, ttyfd, ptymaster; 568 pid_t pid; 569 570 if (s == NULL) 571 fatal("do_exec_pty: no session"); 572 ptyfd = s->ptyfd; 573 ttyfd = s->ttyfd; 574 575 /* 576 * Create another descriptor of the pty master side for use as the 577 * standard input. We could use the original descriptor, but this 578 * simplifies code in server_loop. The descriptor is bidirectional. 579 * Do this before forking (and cleanup in the child) so as to 580 * detect and gracefully fail out-of-fd conditions. 581 */ 582 if ((fdout = dup(ptyfd)) < 0) { 583 error("%s: dup #1: %s", __func__, strerror(errno)); 584 close(ttyfd); 585 close(ptyfd); 586 return -1; 587 } 588 /* we keep a reference to the pty master */ 589 if ((ptymaster = dup(ptyfd)) < 0) { 590 error("%s: dup #2: %s", __func__, strerror(errno)); 591 close(ttyfd); 592 close(ptyfd); 593 close(fdout); 594 return -1; 595 } 596 597 /* Fork the child. */ 598 switch ((pid = fork())) { 599 case -1: 600 error("%s: fork: %.100s", __func__, strerror(errno)); 601 close(fdout); 602 close(ptymaster); 603 close(ttyfd); 604 close(ptyfd); 605 return -1; 606 case 0: 607 is_child = 1; 608 609 close(fdout); 610 close(ptymaster); 611 612 /* Close the master side of the pseudo tty. */ 613 close(ptyfd); 614 615 /* Make the pseudo tty our controlling tty. */ 616 pty_make_controlling_tty(&ttyfd, s->tty); 617 618 /* Redirect stdin/stdout/stderr from the pseudo tty. */ 619 if (dup2(ttyfd, 0) < 0) 620 error("dup2 stdin: %s", strerror(errno)); 621 if (dup2(ttyfd, 1) < 0) 622 error("dup2 stdout: %s", strerror(errno)); 623 if (dup2(ttyfd, 2) < 0) 624 error("dup2 stderr: %s", strerror(errno)); 625 626 /* Close the extra descriptor for the pseudo tty. */ 627 close(ttyfd); 628 629 /* record login, etc. similar to login(1) */ 630 #ifndef HAVE_OSF_SIA 631 do_login(ssh, s, command); 632 #endif 633 /* 634 * Do common processing for the child, such as execing 635 * the command. 636 */ 637 do_child(ssh, s, command); 638 /* NOTREACHED */ 639 default: 640 break; 641 } 642 643 #ifdef HAVE_CYGWIN 644 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); 645 #endif 646 647 s->pid = pid; 648 649 /* Parent. Close the slave side of the pseudo tty. */ 650 close(ttyfd); 651 652 /* Enter interactive session. */ 653 s->ptymaster = ptymaster; 654 packet_set_interactive(1, 655 options.ip_qos_interactive, options.ip_qos_bulk); 656 session_set_fds(ssh, s, ptyfd, fdout, -1, 1, 1); 657 return 0; 658 } 659 660 #ifdef LOGIN_NEEDS_UTMPX 661 static void 662 do_pre_login(Session *s) 663 { 664 struct ssh *ssh = active_state; /* XXX */ 665 socklen_t fromlen; 666 struct sockaddr_storage from; 667 pid_t pid = getpid(); 668 669 /* 670 * Get IP address of client. If the connection is not a socket, let 671 * the address be 0.0.0.0. 672 */ 673 memset(&from, 0, sizeof(from)); 674 fromlen = sizeof(from); 675 if (packet_connection_is_on_socket()) { 676 if (getpeername(packet_get_connection_in(), 677 (struct sockaddr *)&from, &fromlen) < 0) { 678 debug("getpeername: %.100s", strerror(errno)); 679 cleanup_exit(255); 680 } 681 } 682 683 record_utmp_only(pid, s->tty, s->pw->pw_name, 684 session_get_remote_name_or_ip(ssh, utmp_len, options.use_dns), 685 (struct sockaddr *)&from, fromlen); 686 } 687 #endif 688 689 /* 690 * This is called to fork and execute a command. If another command is 691 * to be forced, execute that instead. 692 */ 693 int 694 do_exec(struct ssh *ssh, Session *s, const char *command) 695 { 696 int ret; 697 const char *forced = NULL, *tty = NULL; 698 char session_type[1024]; 699 700 if (options.adm_forced_command) { 701 original_command = command; 702 command = options.adm_forced_command; 703 forced = "(config)"; 704 } else if (auth_opts->force_command != NULL) { 705 original_command = command; 706 command = auth_opts->force_command; 707 forced = "(key-option)"; 708 } 709 if (forced != NULL) { 710 if (IS_INTERNAL_SFTP(command)) { 711 s->is_subsystem = s->is_subsystem ? 712 SUBSYSTEM_INT_SFTP : SUBSYSTEM_INT_SFTP_ERROR; 713 } else if (s->is_subsystem) 714 s->is_subsystem = SUBSYSTEM_EXT; 715 snprintf(session_type, sizeof(session_type), 716 "forced-command %s '%.900s'", forced, command); 717 } else if (s->is_subsystem) { 718 snprintf(session_type, sizeof(session_type), 719 "subsystem '%.900s'", s->subsys); 720 } else if (command == NULL) { 721 snprintf(session_type, sizeof(session_type), "shell"); 722 } else { 723 /* NB. we don't log unforced commands to preserve privacy */ 724 snprintf(session_type, sizeof(session_type), "command"); 725 } 726 727 if (s->ttyfd != -1) { 728 tty = s->tty; 729 if (strncmp(tty, "/dev/", 5) == 0) 730 tty += 5; 731 } 732 733 verbose("Starting session: %s%s%s for %s from %.200s port %d id %d", 734 session_type, 735 tty == NULL ? "" : " on ", 736 tty == NULL ? "" : tty, 737 s->pw->pw_name, 738 ssh_remote_ipaddr(ssh), 739 ssh_remote_port(ssh), 740 s->self); 741 742 #ifdef SSH_AUDIT_EVENTS 743 if (command != NULL) 744 PRIVSEP(audit_run_command(command)); 745 else if (s->ttyfd == -1) { 746 char *shell = s->pw->pw_shell; 747 748 if (shell[0] == '\0') /* empty shell means /bin/sh */ 749 shell =_PATH_BSHELL; 750 PRIVSEP(audit_run_command(shell)); 751 } 752 #endif 753 if (s->ttyfd != -1) 754 ret = do_exec_pty(ssh, s, command); 755 else 756 ret = do_exec_no_pty(ssh, s, command); 757 758 original_command = NULL; 759 760 /* 761 * Clear loginmsg: it's the child's responsibility to display 762 * it to the user, otherwise multiple sessions may accumulate 763 * multiple copies of the login messages. 764 */ 765 sshbuf_reset(loginmsg); 766 767 return ret; 768 } 769 770 /* administrative, login(1)-like work */ 771 void 772 do_login(struct ssh *ssh, Session *s, const char *command) 773 { 774 socklen_t fromlen; 775 struct sockaddr_storage from; 776 struct passwd * pw = s->pw; 777 pid_t pid = getpid(); 778 779 /* 780 * Get IP address of client. If the connection is not a socket, let 781 * the address be 0.0.0.0. 782 */ 783 memset(&from, 0, sizeof(from)); 784 fromlen = sizeof(from); 785 if (packet_connection_is_on_socket()) { 786 if (getpeername(packet_get_connection_in(), 787 (struct sockaddr *)&from, &fromlen) < 0) { 788 debug("getpeername: %.100s", strerror(errno)); 789 cleanup_exit(255); 790 } 791 } 792 793 /* Record that there was a login on that tty from the remote host. */ 794 if (!use_privsep) 795 record_login(pid, s->tty, pw->pw_name, pw->pw_uid, 796 session_get_remote_name_or_ip(ssh, utmp_len, 797 options.use_dns), 798 (struct sockaddr *)&from, fromlen); 799 800 #ifdef USE_PAM 801 /* 802 * If password change is needed, do it now. 803 * This needs to occur before the ~/.hushlogin check. 804 */ 805 if (options.use_pam && !use_privsep && s->authctxt->force_pwchange) { 806 display_loginmsg(); 807 do_pam_chauthtok(); 808 s->authctxt->force_pwchange = 0; 809 /* XXX - signal [net] parent to enable forwardings */ 810 } 811 #endif 812 813 if (check_quietlogin(s, command)) 814 return; 815 816 display_loginmsg(); 817 818 do_motd(); 819 } 820 821 /* 822 * Display the message of the day. 823 */ 824 void 825 do_motd(void) 826 { 827 FILE *f; 828 char buf[256]; 829 830 if (options.print_motd) { 831 #ifdef HAVE_LOGIN_CAP 832 f = fopen(login_getcapstr(lc, "welcome", "/etc/motd", 833 "/etc/motd"), "r"); 834 #else 835 f = fopen("/etc/motd", "r"); 836 #endif 837 if (f) { 838 while (fgets(buf, sizeof(buf), f)) 839 fputs(buf, stdout); 840 fclose(f); 841 } 842 } 843 } 844 845 846 /* 847 * Check for quiet login, either .hushlogin or command given. 848 */ 849 int 850 check_quietlogin(Session *s, const char *command) 851 { 852 char buf[256]; 853 struct passwd *pw = s->pw; 854 struct stat st; 855 856 /* Return 1 if .hushlogin exists or a command given. */ 857 if (command != NULL) 858 return 1; 859 snprintf(buf, sizeof(buf), "%.200s/.hushlogin", pw->pw_dir); 860 #ifdef HAVE_LOGIN_CAP 861 if (login_getcapbool(lc, "hushlogin", 0) || stat(buf, &st) >= 0) 862 return 1; 863 #else 864 if (stat(buf, &st) >= 0) 865 return 1; 866 #endif 867 return 0; 868 } 869 870 /* 871 * Reads environment variables from the given file and adds/overrides them 872 * into the environment. If the file does not exist, this does nothing. 873 * Otherwise, it must consist of empty lines, comments (line starts with '#') 874 * and assignments of the form name=value. No other forms are allowed. 875 * If whitelist is not NULL, then it is interpreted as a pattern list and 876 * only variable names that match it will be accepted. 877 */ 878 static void 879 read_environment_file(char ***env, u_int *envsize, 880 const char *filename, const char *whitelist) 881 { 882 FILE *f; 883 char *line = NULL, *cp, *value; 884 size_t linesize = 0; 885 u_int lineno = 0; 886 887 f = fopen(filename, "r"); 888 if (!f) 889 return; 890 891 while (getline(&line, &linesize, f) != -1) { 892 if (++lineno > 1000) 893 fatal("Too many lines in environment file %s", filename); 894 for (cp = line; *cp == ' ' || *cp == '\t'; cp++) 895 ; 896 if (!*cp || *cp == '#' || *cp == '\n') 897 continue; 898 899 cp[strcspn(cp, "\n")] = '\0'; 900 901 value = strchr(cp, '='); 902 if (value == NULL) { 903 fprintf(stderr, "Bad line %u in %.100s\n", lineno, 904 filename); 905 continue; 906 } 907 /* 908 * Replace the equals sign by nul, and advance value to 909 * the value string. 910 */ 911 *value = '\0'; 912 value++; 913 if (whitelist != NULL && 914 match_pattern_list(cp, whitelist, 0) != 1) 915 continue; 916 child_set_env(env, envsize, cp, value); 917 } 918 free(line); 919 fclose(f); 920 } 921 922 #ifdef HAVE_ETC_DEFAULT_LOGIN 923 /* 924 * Return named variable from specified environment, or NULL if not present. 925 */ 926 static char * 927 child_get_env(char **env, const char *name) 928 { 929 int i; 930 size_t len; 931 932 len = strlen(name); 933 for (i=0; env[i] != NULL; i++) 934 if (strncmp(name, env[i], len) == 0 && env[i][len] == '=') 935 return(env[i] + len + 1); 936 return NULL; 937 } 938 939 /* 940 * Read /etc/default/login. 941 * We pick up the PATH (or SUPATH for root) and UMASK. 942 */ 943 static void 944 read_etc_default_login(char ***env, u_int *envsize, uid_t uid) 945 { 946 char **tmpenv = NULL, *var; 947 u_int i, tmpenvsize = 0; 948 u_long mask; 949 950 /* 951 * We don't want to copy the whole file to the child's environment, 952 * so we use a temporary environment and copy the variables we're 953 * interested in. 954 */ 955 read_environment_file(&tmpenv, &tmpenvsize, "/etc/default/login", 956 options.permit_user_env_whitelist); 957 958 if (tmpenv == NULL) 959 return; 960 961 if (uid == 0) 962 var = child_get_env(tmpenv, "SUPATH"); 963 else 964 var = child_get_env(tmpenv, "PATH"); 965 if (var != NULL) 966 child_set_env(env, envsize, "PATH", var); 967 968 if ((var = child_get_env(tmpenv, "UMASK")) != NULL) 969 if (sscanf(var, "%5lo", &mask) == 1) 970 umask((mode_t)mask); 971 972 for (i = 0; tmpenv[i] != NULL; i++) 973 free(tmpenv[i]); 974 free(tmpenv); 975 } 976 #endif /* HAVE_ETC_DEFAULT_LOGIN */ 977 978 static void 979 copy_environment_blacklist(char **source, char ***env, u_int *envsize, 980 const char *blacklist) 981 { 982 char *var_name, *var_val; 983 int i; 984 985 if (source == NULL) 986 return; 987 988 for(i = 0; source[i] != NULL; i++) { 989 var_name = xstrdup(source[i]); 990 if ((var_val = strstr(var_name, "=")) == NULL) { 991 free(var_name); 992 continue; 993 } 994 *var_val++ = '\0'; 995 996 if (blacklist == NULL || 997 match_pattern_list(var_name, blacklist, 0) != 1) { 998 debug3("Copy environment: %s=%s", var_name, var_val); 999 child_set_env(env, envsize, var_name, var_val); 1000 } 1001 1002 free(var_name); 1003 } 1004 } 1005 1006 void 1007 copy_environment(char **source, char ***env, u_int *envsize) 1008 { 1009 copy_environment_blacklist(source, env, envsize, NULL); 1010 } 1011 1012 static char ** 1013 do_setup_env(struct ssh *ssh, Session *s, const char *shell) 1014 { 1015 char buf[256]; 1016 size_t n; 1017 u_int i, envsize; 1018 char *ocp, *cp, *value, **env, *laddr; 1019 struct passwd *pw = s->pw; 1020 #if !defined (HAVE_LOGIN_CAP) && !defined (HAVE_CYGWIN) 1021 char *path = NULL; 1022 #else 1023 extern char **environ; 1024 char **senv, **var, *val; 1025 #endif 1026 1027 /* Initialize the environment. */ 1028 envsize = 100; 1029 env = xcalloc(envsize, sizeof(char *)); 1030 env[0] = NULL; 1031 1032 #ifdef HAVE_CYGWIN 1033 /* 1034 * The Windows environment contains some setting which are 1035 * important for a running system. They must not be dropped. 1036 */ 1037 { 1038 char **p; 1039 1040 p = fetch_windows_environment(); 1041 copy_environment(p, &env, &envsize); 1042 free_windows_environment(p); 1043 } 1044 #endif 1045 1046 if (getenv("TZ")) 1047 child_set_env(&env, &envsize, "TZ", getenv("TZ")); 1048 1049 #ifdef GSSAPI 1050 /* Allow any GSSAPI methods that we've used to alter 1051 * the childs environment as they see fit 1052 */ 1053 ssh_gssapi_do_child(&env, &envsize); 1054 #endif 1055 1056 /* Set basic environment. */ 1057 for (i = 0; i < s->num_env; i++) 1058 child_set_env(&env, &envsize, s->env[i].name, s->env[i].val); 1059 1060 child_set_env(&env, &envsize, "USER", pw->pw_name); 1061 child_set_env(&env, &envsize, "LOGNAME", pw->pw_name); 1062 #ifdef _AIX 1063 child_set_env(&env, &envsize, "LOGIN", pw->pw_name); 1064 #endif 1065 child_set_env(&env, &envsize, "HOME", pw->pw_dir); 1066 snprintf(buf, sizeof buf, "%.200s/%.50s", _PATH_MAILDIR, pw->pw_name); 1067 child_set_env(&env, &envsize, "MAIL", buf); 1068 #ifdef HAVE_LOGIN_CAP 1069 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); 1070 child_set_env(&env, &envsize, "TERM", "su"); 1071 /* 1072 * Temporarily swap out our real environment with an empty one, 1073 * let setusercontext() apply any environment variables defined 1074 * for the user's login class, copy those variables to the child, 1075 * free the temporary environment, and restore the original. 1076 */ 1077 senv = environ; 1078 environ = xmalloc(sizeof(*environ)); 1079 *environ = NULL; 1080 (void)setusercontext(lc, pw, pw->pw_uid, LOGIN_SETENV|LOGIN_SETPATH); 1081 for (var = environ; *var != NULL; ++var) { 1082 if ((val = strchr(*var, '=')) != NULL) { 1083 *val++ = '\0'; 1084 child_set_env(&env, &envsize, *var, val); 1085 } 1086 free(*var); 1087 } 1088 free(environ); 1089 environ = senv; 1090 #else /* HAVE_LOGIN_CAP */ 1091 # ifndef HAVE_CYGWIN 1092 /* 1093 * There's no standard path on Windows. The path contains 1094 * important components pointing to the system directories, 1095 * needed for loading shared libraries. So the path better 1096 * remains intact here. 1097 */ 1098 # ifdef HAVE_ETC_DEFAULT_LOGIN 1099 read_etc_default_login(&env, &envsize, pw->pw_uid); 1100 path = child_get_env(env, "PATH"); 1101 # endif /* HAVE_ETC_DEFAULT_LOGIN */ 1102 if (path == NULL || *path == '\0') { 1103 child_set_env(&env, &envsize, "PATH", 1104 s->pw->pw_uid == 0 ? SUPERUSER_PATH : _PATH_STDPATH); 1105 } 1106 # endif /* HAVE_CYGWIN */ 1107 #endif /* HAVE_LOGIN_CAP */ 1108 1109 /* Normal systems set SHELL by default. */ 1110 child_set_env(&env, &envsize, "SHELL", shell); 1111 1112 if (s->term) 1113 child_set_env(&env, &envsize, "TERM", s->term); 1114 if (s->display) 1115 child_set_env(&env, &envsize, "DISPLAY", s->display); 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 options.permit_user_env_whitelist); 1137 } 1138 #endif 1139 #ifdef KRB5 1140 if (s->authctxt->krb5_ccname) 1141 child_set_env(&env, &envsize, "KRB5CCNAME", 1142 s->authctxt->krb5_ccname); 1143 #endif 1144 if (auth_sock_name != NULL) 1145 child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME, 1146 auth_sock_name); 1147 1148 1149 /* Set custom environment options from pubkey authentication. */ 1150 if (options.permit_user_env) { 1151 for (n = 0 ; n < auth_opts->nenv; n++) { 1152 ocp = xstrdup(auth_opts->env[n]); 1153 cp = strchr(ocp, '='); 1154 if (*cp == '=') { 1155 *cp = '\0'; 1156 /* Apply PermitUserEnvironment whitelist */ 1157 if (options.permit_user_env_whitelist == NULL || 1158 match_pattern_list(ocp, 1159 options.permit_user_env_whitelist, 0) == 1) 1160 child_set_env(&env, &envsize, 1161 ocp, cp + 1); 1162 } 1163 free(ocp); 1164 } 1165 } 1166 1167 /* read $HOME/.ssh/environment. */ 1168 if (options.permit_user_env) { 1169 snprintf(buf, sizeof buf, "%.200s/.ssh/environment", 1170 pw->pw_dir); 1171 read_environment_file(&env, &envsize, buf, 1172 options.permit_user_env_whitelist); 1173 } 1174 1175 #ifdef USE_PAM 1176 /* 1177 * Pull in any environment variables that may have 1178 * been set by PAM. 1179 */ 1180 if (options.use_pam) { 1181 char **p; 1182 1183 /* 1184 * Don't allow SSH_AUTH_INFO variables posted to PAM to leak 1185 * back into the environment. 1186 */ 1187 p = fetch_pam_child_environment(); 1188 copy_environment_blacklist(p, &env, &envsize, "SSH_AUTH_INFO*"); 1189 free_pam_environment(p); 1190 1191 p = fetch_pam_environment(); 1192 copy_environment_blacklist(p, &env, &envsize, "SSH_AUTH_INFO*"); 1193 free_pam_environment(p); 1194 } 1195 #endif /* USE_PAM */ 1196 1197 /* Environment specified by admin */ 1198 for (i = 0; i < options.num_setenv; i++) { 1199 cp = xstrdup(options.setenv[i]); 1200 if ((value = strchr(cp, '=')) == NULL) { 1201 /* shouldn't happen; vars are checked in servconf.c */ 1202 fatal("Invalid config SetEnv: %s", options.setenv[i]); 1203 } 1204 *value++ = '\0'; 1205 child_set_env(&env, &envsize, cp, value); 1206 } 1207 1208 /* SSH_CLIENT deprecated */ 1209 snprintf(buf, sizeof buf, "%.50s %d %d", 1210 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 1211 ssh_local_port(ssh)); 1212 child_set_env(&env, &envsize, "SSH_CLIENT", buf); 1213 1214 laddr = get_local_ipaddr(packet_get_connection_in()); 1215 snprintf(buf, sizeof buf, "%.50s %d %.50s %d", 1216 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 1217 laddr, ssh_local_port(ssh)); 1218 free(laddr); 1219 child_set_env(&env, &envsize, "SSH_CONNECTION", buf); 1220 1221 if (tun_fwd_ifnames != NULL) 1222 child_set_env(&env, &envsize, "SSH_TUNNEL", tun_fwd_ifnames); 1223 if (auth_info_file != NULL) 1224 child_set_env(&env, &envsize, "SSH_USER_AUTH", auth_info_file); 1225 if (s->ttyfd != -1) 1226 child_set_env(&env, &envsize, "SSH_TTY", s->tty); 1227 if (original_command) 1228 child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND", 1229 original_command); 1230 1231 if (debug_flag) { 1232 /* dump the environment */ 1233 fprintf(stderr, "Environment:\n"); 1234 for (i = 0; env[i]; i++) 1235 fprintf(stderr, " %.200s\n", env[i]); 1236 } 1237 return env; 1238 } 1239 1240 /* 1241 * Run $HOME/.ssh/rc, /etc/ssh/sshrc, or xauth (whichever is found 1242 * first in this order). 1243 */ 1244 static void 1245 do_rc_files(struct ssh *ssh, Session *s, const char *shell) 1246 { 1247 FILE *f = NULL; 1248 char cmd[1024]; 1249 int do_xauth; 1250 struct stat st; 1251 1252 do_xauth = 1253 s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL; 1254 1255 /* ignore _PATH_SSH_USER_RC for subsystems and admin forced commands */ 1256 if (!s->is_subsystem && options.adm_forced_command == NULL && 1257 auth_opts->permit_user_rc && options.permit_user_rc && 1258 stat(_PATH_SSH_USER_RC, &st) >= 0) { 1259 snprintf(cmd, sizeof cmd, "%s -c '%s %s'", 1260 shell, _PATH_BSHELL, _PATH_SSH_USER_RC); 1261 if (debug_flag) 1262 fprintf(stderr, "Running %s\n", cmd); 1263 f = popen(cmd, "w"); 1264 if (f) { 1265 if (do_xauth) 1266 fprintf(f, "%s %s\n", s->auth_proto, 1267 s->auth_data); 1268 pclose(f); 1269 } else 1270 fprintf(stderr, "Could not run %s\n", 1271 _PATH_SSH_USER_RC); 1272 } else if (stat(_PATH_SSH_SYSTEM_RC, &st) >= 0) { 1273 if (debug_flag) 1274 fprintf(stderr, "Running %s %s\n", _PATH_BSHELL, 1275 _PATH_SSH_SYSTEM_RC); 1276 f = popen(_PATH_BSHELL " " _PATH_SSH_SYSTEM_RC, "w"); 1277 if (f) { 1278 if (do_xauth) 1279 fprintf(f, "%s %s\n", s->auth_proto, 1280 s->auth_data); 1281 pclose(f); 1282 } else 1283 fprintf(stderr, "Could not run %s\n", 1284 _PATH_SSH_SYSTEM_RC); 1285 } else if (do_xauth && options.xauth_location != NULL) { 1286 /* Add authority data to .Xauthority if appropriate. */ 1287 if (debug_flag) { 1288 fprintf(stderr, 1289 "Running %.500s remove %.100s\n", 1290 options.xauth_location, s->auth_display); 1291 fprintf(stderr, 1292 "%.500s add %.100s %.100s %.100s\n", 1293 options.xauth_location, s->auth_display, 1294 s->auth_proto, s->auth_data); 1295 } 1296 snprintf(cmd, sizeof cmd, "%s -q -", 1297 options.xauth_location); 1298 f = popen(cmd, "w"); 1299 if (f) { 1300 fprintf(f, "remove %s\n", 1301 s->auth_display); 1302 fprintf(f, "add %s %s %s\n", 1303 s->auth_display, s->auth_proto, 1304 s->auth_data); 1305 pclose(f); 1306 } else { 1307 fprintf(stderr, "Could not run %s\n", 1308 cmd); 1309 } 1310 } 1311 } 1312 1313 static void 1314 do_nologin(struct passwd *pw) 1315 { 1316 FILE *f = NULL; 1317 const char *nl; 1318 char buf[1024], *def_nl = _PATH_NOLOGIN; 1319 struct stat sb; 1320 1321 #ifdef HAVE_LOGIN_CAP 1322 if (login_getcapbool(lc, "ignorenologin", 0) || pw->pw_uid == 0) 1323 return; 1324 nl = login_getcapstr(lc, "nologin", def_nl, def_nl); 1325 #else 1326 if (pw->pw_uid == 0) 1327 return; 1328 nl = def_nl; 1329 #endif 1330 if (stat(nl, &sb) == -1) 1331 return; 1332 1333 /* /etc/nologin exists. Print its contents if we can and exit. */ 1334 logit("User %.100s not allowed because %s exists", pw->pw_name, nl); 1335 if ((f = fopen(nl, "r")) != NULL) { 1336 while (fgets(buf, sizeof(buf), f)) 1337 fputs(buf, stderr); 1338 fclose(f); 1339 } 1340 exit(254); 1341 } 1342 1343 /* 1344 * Chroot into a directory after checking it for safety: all path components 1345 * must be root-owned directories with strict permissions. 1346 */ 1347 static void 1348 safely_chroot(const char *path, uid_t uid) 1349 { 1350 const char *cp; 1351 char component[PATH_MAX]; 1352 struct stat st; 1353 1354 if (*path != '/') 1355 fatal("chroot path does not begin at root"); 1356 if (strlen(path) >= sizeof(component)) 1357 fatal("chroot path too long"); 1358 1359 /* 1360 * Descend the path, checking that each component is a 1361 * root-owned directory with strict permissions. 1362 */ 1363 for (cp = path; cp != NULL;) { 1364 if ((cp = strchr(cp, '/')) == NULL) 1365 strlcpy(component, path, sizeof(component)); 1366 else { 1367 cp++; 1368 memcpy(component, path, cp - path); 1369 component[cp - path] = '\0'; 1370 } 1371 1372 debug3("%s: checking '%s'", __func__, component); 1373 1374 if (stat(component, &st) != 0) 1375 fatal("%s: stat(\"%s\"): %s", __func__, 1376 component, strerror(errno)); 1377 if (st.st_uid != 0 || (st.st_mode & 022) != 0) 1378 fatal("bad ownership or modes for chroot " 1379 "directory %s\"%s\"", 1380 cp == NULL ? "" : "component ", component); 1381 if (!S_ISDIR(st.st_mode)) 1382 fatal("chroot path %s\"%s\" is not a directory", 1383 cp == NULL ? "" : "component ", component); 1384 1385 } 1386 1387 if (chdir(path) == -1) 1388 fatal("Unable to chdir to chroot path \"%s\": " 1389 "%s", path, strerror(errno)); 1390 if (chroot(path) == -1) 1391 fatal("chroot(\"%s\"): %s", path, strerror(errno)); 1392 if (chdir("/") == -1) 1393 fatal("%s: chdir(/) after chroot: %s", 1394 __func__, strerror(errno)); 1395 verbose("Changed root directory to \"%s\"", path); 1396 } 1397 1398 /* Set login name, uid, gid, and groups. */ 1399 void 1400 do_setusercontext(struct passwd *pw) 1401 { 1402 char uidstr[32], *chroot_path, *tmp; 1403 1404 platform_setusercontext(pw); 1405 1406 if (platform_privileged_uidswap()) { 1407 #ifdef HAVE_LOGIN_CAP 1408 if (setusercontext(lc, pw, pw->pw_uid, 1409 (LOGIN_SETALL & ~(LOGIN_SETENV|LOGIN_SETPATH|LOGIN_SETUSER))) < 0) { 1410 perror("unable to set user context"); 1411 exit(1); 1412 } 1413 #else 1414 if (setlogin(pw->pw_name) < 0) 1415 error("setlogin failed: %s", strerror(errno)); 1416 if (setgid(pw->pw_gid) < 0) { 1417 perror("setgid"); 1418 exit(1); 1419 } 1420 /* Initialize the group list. */ 1421 if (initgroups(pw->pw_name, pw->pw_gid) < 0) { 1422 perror("initgroups"); 1423 exit(1); 1424 } 1425 endgrent(); 1426 #endif 1427 1428 platform_setusercontext_post_groups(pw); 1429 1430 if (!in_chroot && options.chroot_directory != NULL && 1431 strcasecmp(options.chroot_directory, "none") != 0) { 1432 tmp = tilde_expand_filename(options.chroot_directory, 1433 pw->pw_uid); 1434 snprintf(uidstr, sizeof(uidstr), "%llu", 1435 (unsigned long long)pw->pw_uid); 1436 chroot_path = percent_expand(tmp, "h", pw->pw_dir, 1437 "u", pw->pw_name, "U", uidstr, (char *)NULL); 1438 safely_chroot(chroot_path, pw->pw_uid); 1439 free(tmp); 1440 free(chroot_path); 1441 /* Make sure we don't attempt to chroot again */ 1442 free(options.chroot_directory); 1443 options.chroot_directory = NULL; 1444 in_chroot = 1; 1445 } 1446 1447 #ifdef HAVE_LOGIN_CAP 1448 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUSER) < 0) { 1449 perror("unable to set user context (setuser)"); 1450 exit(1); 1451 } 1452 /* 1453 * FreeBSD's setusercontext() will not apply the user's 1454 * own umask setting unless running with the user's UID. 1455 */ 1456 (void) setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUMASK); 1457 #else 1458 # ifdef USE_LIBIAF 1459 /* 1460 * In a chroot environment, the set_id() will always fail; 1461 * typically because of the lack of necessary authentication 1462 * services and runtime such as ./usr/lib/libiaf.so, 1463 * ./usr/lib/libpam.so.1, and ./etc/passwd We skip it in the 1464 * internal sftp chroot case. We'll lose auditing and ACLs but 1465 * permanently_set_uid will take care of the rest. 1466 */ 1467 if (!in_chroot && set_id(pw->pw_name) != 0) 1468 fatal("set_id(%s) Failed", pw->pw_name); 1469 # endif /* USE_LIBIAF */ 1470 /* Permanently switch to the desired uid. */ 1471 permanently_set_uid(pw); 1472 #endif 1473 } else if (options.chroot_directory != NULL && 1474 strcasecmp(options.chroot_directory, "none") != 0) { 1475 fatal("server lacks privileges to chroot to ChrootDirectory"); 1476 } 1477 1478 if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) 1479 fatal("Failed to set uids to %u.", (u_int) pw->pw_uid); 1480 } 1481 1482 static void 1483 do_pwchange(Session *s) 1484 { 1485 fflush(NULL); 1486 fprintf(stderr, "WARNING: Your password has expired.\n"); 1487 if (s->ttyfd != -1) { 1488 fprintf(stderr, 1489 "You must change your password now and login again!\n"); 1490 #ifdef WITH_SELINUX 1491 setexeccon(NULL); 1492 #endif 1493 #ifdef PASSWD_NEEDS_USERNAME 1494 execl(_PATH_PASSWD_PROG, "passwd", s->pw->pw_name, 1495 (char *)NULL); 1496 #else 1497 execl(_PATH_PASSWD_PROG, "passwd", (char *)NULL); 1498 #endif 1499 perror("passwd"); 1500 } else { 1501 fprintf(stderr, 1502 "Password change required but no TTY available.\n"); 1503 } 1504 exit(1); 1505 } 1506 1507 static void 1508 child_close_fds(struct ssh *ssh) 1509 { 1510 extern int auth_sock; 1511 1512 if (auth_sock != -1) { 1513 close(auth_sock); 1514 auth_sock = -1; 1515 } 1516 1517 if (packet_get_connection_in() == packet_get_connection_out()) 1518 close(packet_get_connection_in()); 1519 else { 1520 close(packet_get_connection_in()); 1521 close(packet_get_connection_out()); 1522 } 1523 /* 1524 * Close all descriptors related to channels. They will still remain 1525 * open in the parent. 1526 */ 1527 /* XXX better use close-on-exec? -markus */ 1528 channel_close_all(ssh); 1529 1530 /* 1531 * Close any extra file descriptors. Note that there may still be 1532 * descriptors left by system functions. They will be closed later. 1533 */ 1534 endpwent(); 1535 1536 /* 1537 * Close any extra open file descriptors so that we don't have them 1538 * hanging around in clients. Note that we want to do this after 1539 * initgroups, because at least on Solaris 2.3 it leaves file 1540 * descriptors open. 1541 */ 1542 closefrom(STDERR_FILENO + 1); 1543 } 1544 1545 /* 1546 * Performs common processing for the child, such as setting up the 1547 * environment, closing extra file descriptors, setting the user and group 1548 * ids, and executing the command or shell. 1549 */ 1550 #define ARGV_MAX 10 1551 void 1552 do_child(struct ssh *ssh, Session *s, const char *command) 1553 { 1554 extern char **environ; 1555 char **env; 1556 char *argv[ARGV_MAX]; 1557 const char *shell, *shell0; 1558 struct passwd *pw = s->pw; 1559 int r = 0; 1560 1561 /* remove hostkey from the child's memory */ 1562 destroy_sensitive_data(); 1563 packet_clear_keys(); 1564 1565 /* Force a password change */ 1566 if (s->authctxt->force_pwchange) { 1567 do_setusercontext(pw); 1568 child_close_fds(ssh); 1569 do_pwchange(s); 1570 exit(1); 1571 } 1572 1573 /* 1574 * Login(1) does this as well, and it needs uid 0 for the "-h" 1575 * switch, so we let login(1) to this for us. 1576 */ 1577 #ifdef HAVE_OSF_SIA 1578 session_setup_sia(pw, s->ttyfd == -1 ? NULL : s->tty); 1579 if (!check_quietlogin(s, command)) 1580 do_motd(); 1581 #else /* HAVE_OSF_SIA */ 1582 /* When PAM is enabled we rely on it to do the nologin check */ 1583 if (!options.use_pam) 1584 do_nologin(pw); 1585 do_setusercontext(pw); 1586 /* 1587 * PAM session modules in do_setusercontext may have 1588 * generated messages, so if this in an interactive 1589 * login then display them too. 1590 */ 1591 if (!check_quietlogin(s, command)) 1592 display_loginmsg(); 1593 #endif /* HAVE_OSF_SIA */ 1594 1595 #ifdef USE_PAM 1596 if (options.use_pam && !is_pam_session_open()) { 1597 debug3("PAM session not opened, exiting"); 1598 display_loginmsg(); 1599 exit(254); 1600 } 1601 #endif 1602 1603 /* 1604 * Get the shell from the password data. An empty shell field is 1605 * legal, and means /bin/sh. 1606 */ 1607 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; 1608 1609 /* 1610 * Make sure $SHELL points to the shell from the password file, 1611 * even if shell is overridden from login.conf 1612 */ 1613 env = do_setup_env(ssh, s, shell); 1614 1615 #ifdef HAVE_LOGIN_CAP 1616 shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell); 1617 #endif 1618 1619 /* 1620 * Close the connection descriptors; note that this is the child, and 1621 * the server will still have the socket open, and it is important 1622 * that we do not shutdown it. Note that the descriptors cannot be 1623 * closed before building the environment, as we call 1624 * ssh_remote_ipaddr there. 1625 */ 1626 child_close_fds(ssh); 1627 1628 /* 1629 * Must take new environment into use so that .ssh/rc, 1630 * /etc/ssh/sshrc and xauth are run in the proper environment. 1631 */ 1632 environ = env; 1633 1634 #if defined(KRB5) && defined(USE_AFS) 1635 /* 1636 * At this point, we check to see if AFS is active and if we have 1637 * a valid Kerberos 5 TGT. If so, it seems like a good idea to see 1638 * if we can (and need to) extend the ticket into an AFS token. If 1639 * we don't do this, we run into potential problems if the user's 1640 * home directory is in AFS and it's not world-readable. 1641 */ 1642 1643 if (options.kerberos_get_afs_token && k_hasafs() && 1644 (s->authctxt->krb5_ctx != NULL)) { 1645 char cell[64]; 1646 1647 debug("Getting AFS token"); 1648 1649 k_setpag(); 1650 1651 if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0) 1652 krb5_afslog(s->authctxt->krb5_ctx, 1653 s->authctxt->krb5_fwd_ccache, cell, NULL); 1654 1655 krb5_afslog_home(s->authctxt->krb5_ctx, 1656 s->authctxt->krb5_fwd_ccache, NULL, NULL, pw->pw_dir); 1657 } 1658 #endif 1659 1660 /* Change current directory to the user's home directory. */ 1661 if (chdir(pw->pw_dir) < 0) { 1662 /* Suppress missing homedir warning for chroot case */ 1663 #ifdef HAVE_LOGIN_CAP 1664 r = login_getcapbool(lc, "requirehome", 0); 1665 #endif 1666 if (r || !in_chroot) { 1667 fprintf(stderr, "Could not chdir to home " 1668 "directory %s: %s\n", pw->pw_dir, 1669 strerror(errno)); 1670 } 1671 if (r) 1672 exit(1); 1673 } 1674 1675 closefrom(STDERR_FILENO + 1); 1676 1677 do_rc_files(ssh, s, shell); 1678 1679 /* restore SIGPIPE for child */ 1680 signal(SIGPIPE, SIG_DFL); 1681 1682 if (s->is_subsystem == SUBSYSTEM_INT_SFTP_ERROR) { 1683 printf("This service allows sftp connections only.\n"); 1684 fflush(NULL); 1685 exit(1); 1686 } else if (s->is_subsystem == SUBSYSTEM_INT_SFTP) { 1687 extern int optind, optreset; 1688 int i; 1689 char *p, *args; 1690 1691 setproctitle("%s@%s", s->pw->pw_name, INTERNAL_SFTP_NAME); 1692 args = xstrdup(command ? command : "sftp-server"); 1693 for (i = 0, (p = strtok(args, " ")); p; (p = strtok(NULL, " "))) 1694 if (i < ARGV_MAX - 1) 1695 argv[i++] = p; 1696 argv[i] = NULL; 1697 optind = optreset = 1; 1698 __progname = argv[0]; 1699 #ifdef WITH_SELINUX 1700 ssh_selinux_change_context("sftpd_t"); 1701 #endif 1702 exit(sftp_server_main(i, argv, s->pw)); 1703 } 1704 1705 fflush(NULL); 1706 1707 /* Get the last component of the shell name. */ 1708 if ((shell0 = strrchr(shell, '/')) != NULL) 1709 shell0++; 1710 else 1711 shell0 = shell; 1712 1713 /* 1714 * If we have no command, execute the shell. In this case, the shell 1715 * name to be passed in argv[0] is preceded by '-' to indicate that 1716 * this is a login shell. 1717 */ 1718 if (!command) { 1719 char argv0[256]; 1720 1721 /* Start the shell. Set initial character to '-'. */ 1722 argv0[0] = '-'; 1723 1724 if (strlcpy(argv0 + 1, shell0, sizeof(argv0) - 1) 1725 >= sizeof(argv0) - 1) { 1726 errno = EINVAL; 1727 perror(shell); 1728 exit(1); 1729 } 1730 1731 /* Execute the shell. */ 1732 argv[0] = argv0; 1733 argv[1] = NULL; 1734 execve(shell, argv, env); 1735 1736 /* Executing the shell failed. */ 1737 perror(shell); 1738 exit(1); 1739 } 1740 /* 1741 * Execute the command using the user's shell. This uses the -c 1742 * option to execute the command. 1743 */ 1744 argv[0] = (char *) shell0; 1745 argv[1] = "-c"; 1746 argv[2] = (char *) command; 1747 argv[3] = NULL; 1748 execve(shell, argv, env); 1749 perror(shell); 1750 exit(1); 1751 } 1752 1753 void 1754 session_unused(int id) 1755 { 1756 debug3("%s: session id %d unused", __func__, id); 1757 if (id >= options.max_sessions || 1758 id >= sessions_nalloc) { 1759 fatal("%s: insane session id %d (max %d nalloc %d)", 1760 __func__, id, options.max_sessions, sessions_nalloc); 1761 } 1762 memset(&sessions[id], 0, sizeof(*sessions)); 1763 sessions[id].self = id; 1764 sessions[id].used = 0; 1765 sessions[id].chanid = -1; 1766 sessions[id].ptyfd = -1; 1767 sessions[id].ttyfd = -1; 1768 sessions[id].ptymaster = -1; 1769 sessions[id].x11_chanids = NULL; 1770 sessions[id].next_unused = sessions_first_unused; 1771 sessions_first_unused = id; 1772 } 1773 1774 Session * 1775 session_new(void) 1776 { 1777 Session *s, *tmp; 1778 1779 if (sessions_first_unused == -1) { 1780 if (sessions_nalloc >= options.max_sessions) 1781 return NULL; 1782 debug2("%s: allocate (allocated %d max %d)", 1783 __func__, sessions_nalloc, options.max_sessions); 1784 tmp = xrecallocarray(sessions, sessions_nalloc, 1785 sessions_nalloc + 1, sizeof(*sessions)); 1786 if (tmp == NULL) { 1787 error("%s: cannot allocate %d sessions", 1788 __func__, sessions_nalloc + 1); 1789 return NULL; 1790 } 1791 sessions = tmp; 1792 session_unused(sessions_nalloc++); 1793 } 1794 1795 if (sessions_first_unused >= sessions_nalloc || 1796 sessions_first_unused < 0) { 1797 fatal("%s: insane first_unused %d max %d nalloc %d", 1798 __func__, sessions_first_unused, options.max_sessions, 1799 sessions_nalloc); 1800 } 1801 1802 s = &sessions[sessions_first_unused]; 1803 if (s->used) { 1804 fatal("%s: session %d already used", 1805 __func__, sessions_first_unused); 1806 } 1807 sessions_first_unused = s->next_unused; 1808 s->used = 1; 1809 s->next_unused = -1; 1810 debug("session_new: session %d", s->self); 1811 1812 return s; 1813 } 1814 1815 static void 1816 session_dump(void) 1817 { 1818 int i; 1819 for (i = 0; i < sessions_nalloc; i++) { 1820 Session *s = &sessions[i]; 1821 1822 debug("dump: used %d next_unused %d session %d %p " 1823 "channel %d pid %ld", 1824 s->used, 1825 s->next_unused, 1826 s->self, 1827 s, 1828 s->chanid, 1829 (long)s->pid); 1830 } 1831 } 1832 1833 int 1834 session_open(Authctxt *authctxt, int chanid) 1835 { 1836 Session *s = session_new(); 1837 debug("session_open: channel %d", chanid); 1838 if (s == NULL) { 1839 error("no more sessions"); 1840 return 0; 1841 } 1842 s->authctxt = authctxt; 1843 s->pw = authctxt->pw; 1844 if (s->pw == NULL || !authctxt->valid) 1845 fatal("no user for session %d", s->self); 1846 debug("session_open: session %d: link with channel %d", s->self, chanid); 1847 s->chanid = chanid; 1848 return 1; 1849 } 1850 1851 Session * 1852 session_by_tty(char *tty) 1853 { 1854 int i; 1855 for (i = 0; i < sessions_nalloc; i++) { 1856 Session *s = &sessions[i]; 1857 if (s->used && s->ttyfd != -1 && strcmp(s->tty, tty) == 0) { 1858 debug("session_by_tty: session %d tty %s", i, tty); 1859 return s; 1860 } 1861 } 1862 debug("session_by_tty: unknown tty %.100s", tty); 1863 session_dump(); 1864 return NULL; 1865 } 1866 1867 static Session * 1868 session_by_channel(int id) 1869 { 1870 int i; 1871 for (i = 0; i < sessions_nalloc; i++) { 1872 Session *s = &sessions[i]; 1873 if (s->used && s->chanid == id) { 1874 debug("session_by_channel: session %d channel %d", 1875 i, id); 1876 return s; 1877 } 1878 } 1879 debug("session_by_channel: unknown channel %d", id); 1880 session_dump(); 1881 return NULL; 1882 } 1883 1884 static Session * 1885 session_by_x11_channel(int id) 1886 { 1887 int i, j; 1888 1889 for (i = 0; i < sessions_nalloc; i++) { 1890 Session *s = &sessions[i]; 1891 1892 if (s->x11_chanids == NULL || !s->used) 1893 continue; 1894 for (j = 0; s->x11_chanids[j] != -1; j++) { 1895 if (s->x11_chanids[j] == id) { 1896 debug("session_by_x11_channel: session %d " 1897 "channel %d", s->self, id); 1898 return s; 1899 } 1900 } 1901 } 1902 debug("session_by_x11_channel: unknown channel %d", id); 1903 session_dump(); 1904 return NULL; 1905 } 1906 1907 static Session * 1908 session_by_pid(pid_t pid) 1909 { 1910 int i; 1911 debug("session_by_pid: pid %ld", (long)pid); 1912 for (i = 0; i < sessions_nalloc; i++) { 1913 Session *s = &sessions[i]; 1914 if (s->used && s->pid == pid) 1915 return s; 1916 } 1917 error("session_by_pid: unknown pid %ld", (long)pid); 1918 session_dump(); 1919 return NULL; 1920 } 1921 1922 static int 1923 session_window_change_req(struct ssh *ssh, Session *s) 1924 { 1925 s->col = packet_get_int(); 1926 s->row = packet_get_int(); 1927 s->xpixel = packet_get_int(); 1928 s->ypixel = packet_get_int(); 1929 packet_check_eom(); 1930 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 1931 return 1; 1932 } 1933 1934 static int 1935 session_pty_req(struct ssh *ssh, Session *s) 1936 { 1937 u_int len; 1938 1939 if (!auth_opts->permit_pty_flag || !options.permit_tty) { 1940 debug("Allocating a pty not permitted for this connection."); 1941 return 0; 1942 } 1943 if (s->ttyfd != -1) { 1944 packet_disconnect("Protocol error: you already have a pty."); 1945 return 0; 1946 } 1947 1948 s->term = packet_get_string(&len); 1949 s->col = packet_get_int(); 1950 s->row = packet_get_int(); 1951 s->xpixel = packet_get_int(); 1952 s->ypixel = packet_get_int(); 1953 1954 if (strcmp(s->term, "") == 0) { 1955 free(s->term); 1956 s->term = NULL; 1957 } 1958 1959 /* Allocate a pty and open it. */ 1960 debug("Allocating pty."); 1961 if (!PRIVSEP(pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, 1962 sizeof(s->tty)))) { 1963 free(s->term); 1964 s->term = NULL; 1965 s->ptyfd = -1; 1966 s->ttyfd = -1; 1967 error("session_pty_req: session %d alloc failed", s->self); 1968 return 0; 1969 } 1970 debug("session_pty_req: session %d alloc %s", s->self, s->tty); 1971 1972 ssh_tty_parse_modes(ssh, s->ttyfd); 1973 1974 if (!use_privsep) 1975 pty_setowner(s->pw, s->tty); 1976 1977 /* Set window size from the packet. */ 1978 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 1979 1980 packet_check_eom(); 1981 session_proctitle(s); 1982 return 1; 1983 } 1984 1985 static int 1986 session_subsystem_req(struct ssh *ssh, Session *s) 1987 { 1988 struct stat st; 1989 u_int len; 1990 int success = 0; 1991 char *prog, *cmd; 1992 u_int i; 1993 1994 s->subsys = packet_get_string(&len); 1995 packet_check_eom(); 1996 debug2("subsystem request for %.100s by user %s", s->subsys, 1997 s->pw->pw_name); 1998 1999 for (i = 0; i < options.num_subsystems; i++) { 2000 if (strcmp(s->subsys, options.subsystem_name[i]) == 0) { 2001 prog = options.subsystem_command[i]; 2002 cmd = options.subsystem_args[i]; 2003 if (strcmp(INTERNAL_SFTP_NAME, prog) == 0) { 2004 s->is_subsystem = SUBSYSTEM_INT_SFTP; 2005 debug("subsystem: %s", prog); 2006 } else { 2007 if (stat(prog, &st) < 0) 2008 debug("subsystem: cannot stat %s: %s", 2009 prog, strerror(errno)); 2010 s->is_subsystem = SUBSYSTEM_EXT; 2011 debug("subsystem: exec() %s", cmd); 2012 } 2013 success = do_exec(ssh, s, cmd) == 0; 2014 break; 2015 } 2016 } 2017 2018 if (!success) 2019 logit("subsystem request for %.100s by user %s failed, " 2020 "subsystem not found", s->subsys, s->pw->pw_name); 2021 2022 return success; 2023 } 2024 2025 static int 2026 session_x11_req(struct ssh *ssh, Session *s) 2027 { 2028 int success; 2029 2030 if (s->auth_proto != NULL || s->auth_data != NULL) { 2031 error("session_x11_req: session %d: " 2032 "x11 forwarding already active", s->self); 2033 return 0; 2034 } 2035 s->single_connection = packet_get_char(); 2036 s->auth_proto = packet_get_string(NULL); 2037 s->auth_data = packet_get_string(NULL); 2038 s->screen = packet_get_int(); 2039 packet_check_eom(); 2040 2041 if (xauth_valid_string(s->auth_proto) && 2042 xauth_valid_string(s->auth_data)) 2043 success = session_setup_x11fwd(ssh, s); 2044 else { 2045 success = 0; 2046 error("Invalid X11 forwarding data"); 2047 } 2048 if (!success) { 2049 free(s->auth_proto); 2050 free(s->auth_data); 2051 s->auth_proto = NULL; 2052 s->auth_data = NULL; 2053 } 2054 return success; 2055 } 2056 2057 static int 2058 session_shell_req(struct ssh *ssh, Session *s) 2059 { 2060 packet_check_eom(); 2061 return do_exec(ssh, s, NULL) == 0; 2062 } 2063 2064 static int 2065 session_exec_req(struct ssh *ssh, Session *s) 2066 { 2067 u_int len, success; 2068 2069 char *command = packet_get_string(&len); 2070 packet_check_eom(); 2071 success = do_exec(ssh, s, command) == 0; 2072 free(command); 2073 return success; 2074 } 2075 2076 static int 2077 session_break_req(struct ssh *ssh, Session *s) 2078 { 2079 2080 packet_get_int(); /* ignored */ 2081 packet_check_eom(); 2082 2083 if (s->ptymaster == -1 || tcsendbreak(s->ptymaster, 0) < 0) 2084 return 0; 2085 return 1; 2086 } 2087 2088 static int 2089 session_env_req(struct ssh *ssh, Session *s) 2090 { 2091 char *name, *val; 2092 u_int name_len, val_len, i; 2093 2094 name = packet_get_cstring(&name_len); 2095 val = packet_get_cstring(&val_len); 2096 packet_check_eom(); 2097 2098 /* Don't set too many environment variables */ 2099 if (s->num_env > 128) { 2100 debug2("Ignoring env request %s: too many env vars", name); 2101 goto fail; 2102 } 2103 2104 for (i = 0; i < options.num_accept_env; i++) { 2105 if (match_pattern(name, options.accept_env[i])) { 2106 debug2("Setting env %d: %s=%s", s->num_env, name, val); 2107 s->env = xrecallocarray(s->env, s->num_env, 2108 s->num_env + 1, sizeof(*s->env)); 2109 s->env[s->num_env].name = name; 2110 s->env[s->num_env].val = val; 2111 s->num_env++; 2112 return (1); 2113 } 2114 } 2115 debug2("Ignoring env request %s: disallowed name", name); 2116 2117 fail: 2118 free(name); 2119 free(val); 2120 return (0); 2121 } 2122 2123 static int 2124 session_auth_agent_req(struct ssh *ssh, Session *s) 2125 { 2126 static int called = 0; 2127 2128 packet_check_eom(); 2129 if (!auth_opts->permit_agent_forwarding_flag || 2130 !options.allow_agent_forwarding) { 2131 debug("%s: agent forwarding disabled", __func__); 2132 return 0; 2133 } 2134 if (called) { 2135 return 0; 2136 } else { 2137 called = 1; 2138 return auth_input_request_forwarding(ssh, s->pw); 2139 } 2140 } 2141 2142 int 2143 session_input_channel_req(struct ssh *ssh, Channel *c, const char *rtype) 2144 { 2145 int success = 0; 2146 Session *s; 2147 2148 if ((s = session_by_channel(c->self)) == NULL) { 2149 logit("%s: no session %d req %.100s", __func__, c->self, rtype); 2150 return 0; 2151 } 2152 debug("%s: session %d req %s", __func__, s->self, rtype); 2153 2154 /* 2155 * a session is in LARVAL state until a shell, a command 2156 * or a subsystem is executed 2157 */ 2158 if (c->type == SSH_CHANNEL_LARVAL) { 2159 if (strcmp(rtype, "shell") == 0) { 2160 success = session_shell_req(ssh, s); 2161 } else if (strcmp(rtype, "exec") == 0) { 2162 success = session_exec_req(ssh, s); 2163 } else if (strcmp(rtype, "pty-req") == 0) { 2164 success = session_pty_req(ssh, s); 2165 } else if (strcmp(rtype, "x11-req") == 0) { 2166 success = session_x11_req(ssh, s); 2167 } else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) { 2168 success = session_auth_agent_req(ssh, s); 2169 } else if (strcmp(rtype, "subsystem") == 0) { 2170 success = session_subsystem_req(ssh, s); 2171 } else if (strcmp(rtype, "env") == 0) { 2172 success = session_env_req(ssh, s); 2173 } 2174 } 2175 if (strcmp(rtype, "window-change") == 0) { 2176 success = session_window_change_req(ssh, s); 2177 } else if (strcmp(rtype, "break") == 0) { 2178 success = session_break_req(ssh, s); 2179 } 2180 2181 return success; 2182 } 2183 2184 void 2185 session_set_fds(struct ssh *ssh, Session *s, 2186 int fdin, int fdout, int fderr, int ignore_fderr, int is_tty) 2187 { 2188 /* 2189 * now that have a child and a pipe to the child, 2190 * we can activate our channel and register the fd's 2191 */ 2192 if (s->chanid == -1) 2193 fatal("no channel for session %d", s->self); 2194 channel_set_fds(ssh, s->chanid, 2195 fdout, fdin, fderr, 2196 ignore_fderr ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ, 2197 1, is_tty, CHAN_SES_WINDOW_DEFAULT); 2198 } 2199 2200 /* 2201 * Function to perform pty cleanup. Also called if we get aborted abnormally 2202 * (e.g., due to a dropped connection). 2203 */ 2204 void 2205 session_pty_cleanup2(Session *s) 2206 { 2207 if (s == NULL) { 2208 error("session_pty_cleanup: no session"); 2209 return; 2210 } 2211 if (s->ttyfd == -1) 2212 return; 2213 2214 debug("session_pty_cleanup: session %d release %s", s->self, s->tty); 2215 2216 /* Record that the user has logged out. */ 2217 if (s->pid != 0) 2218 record_logout(s->pid, s->tty, s->pw->pw_name); 2219 2220 /* Release the pseudo-tty. */ 2221 if (getuid() == 0) 2222 pty_release(s->tty); 2223 2224 /* 2225 * Close the server side of the socket pairs. We must do this after 2226 * the pty cleanup, so that another process doesn't get this pty 2227 * while we're still cleaning up. 2228 */ 2229 if (s->ptymaster != -1 && close(s->ptymaster) < 0) 2230 error("close(s->ptymaster/%d): %s", 2231 s->ptymaster, strerror(errno)); 2232 2233 /* unlink pty from session */ 2234 s->ttyfd = -1; 2235 } 2236 2237 void 2238 session_pty_cleanup(Session *s) 2239 { 2240 PRIVSEP(session_pty_cleanup2(s)); 2241 } 2242 2243 static char * 2244 sig2name(int sig) 2245 { 2246 #define SSH_SIG(x) if (sig == SIG ## x) return #x 2247 SSH_SIG(ABRT); 2248 SSH_SIG(ALRM); 2249 SSH_SIG(FPE); 2250 SSH_SIG(HUP); 2251 SSH_SIG(ILL); 2252 SSH_SIG(INT); 2253 SSH_SIG(KILL); 2254 SSH_SIG(PIPE); 2255 SSH_SIG(QUIT); 2256 SSH_SIG(SEGV); 2257 SSH_SIG(TERM); 2258 SSH_SIG(USR1); 2259 SSH_SIG(USR2); 2260 #undef SSH_SIG 2261 return "SIG@openssh.com"; 2262 } 2263 2264 static void 2265 session_close_x11(struct ssh *ssh, int id) 2266 { 2267 Channel *c; 2268 2269 if ((c = channel_by_id(ssh, id)) == NULL) { 2270 debug("%s: x11 channel %d missing", __func__, id); 2271 } else { 2272 /* Detach X11 listener */ 2273 debug("%s: detach x11 channel %d", __func__, id); 2274 channel_cancel_cleanup(ssh, id); 2275 if (c->ostate != CHAN_OUTPUT_CLOSED) 2276 chan_mark_dead(ssh, c); 2277 } 2278 } 2279 2280 static void 2281 session_close_single_x11(struct ssh *ssh, int id, void *arg) 2282 { 2283 Session *s; 2284 u_int i; 2285 2286 debug3("%s: channel %d", __func__, id); 2287 channel_cancel_cleanup(ssh, id); 2288 if ((s = session_by_x11_channel(id)) == NULL) 2289 fatal("%s: no x11 channel %d", __func__, id); 2290 for (i = 0; s->x11_chanids[i] != -1; i++) { 2291 debug("%s: session %d: closing channel %d", 2292 __func__, s->self, s->x11_chanids[i]); 2293 /* 2294 * The channel "id" is already closing, but make sure we 2295 * close all of its siblings. 2296 */ 2297 if (s->x11_chanids[i] != id) 2298 session_close_x11(ssh, s->x11_chanids[i]); 2299 } 2300 free(s->x11_chanids); 2301 s->x11_chanids = NULL; 2302 free(s->display); 2303 s->display = NULL; 2304 free(s->auth_proto); 2305 s->auth_proto = NULL; 2306 free(s->auth_data); 2307 s->auth_data = NULL; 2308 free(s->auth_display); 2309 s->auth_display = NULL; 2310 } 2311 2312 static void 2313 session_exit_message(struct ssh *ssh, Session *s, int status) 2314 { 2315 Channel *c; 2316 2317 if ((c = channel_lookup(ssh, s->chanid)) == NULL) 2318 fatal("%s: session %d: no channel %d", 2319 __func__, s->self, s->chanid); 2320 debug("%s: session %d channel %d pid %ld", 2321 __func__, s->self, s->chanid, (long)s->pid); 2322 2323 if (WIFEXITED(status)) { 2324 channel_request_start(ssh, s->chanid, "exit-status", 0); 2325 packet_put_int(WEXITSTATUS(status)); 2326 packet_send(); 2327 } else if (WIFSIGNALED(status)) { 2328 channel_request_start(ssh, s->chanid, "exit-signal", 0); 2329 packet_put_cstring(sig2name(WTERMSIG(status))); 2330 #ifdef WCOREDUMP 2331 packet_put_char(WCOREDUMP(status)? 1 : 0); 2332 #else /* WCOREDUMP */ 2333 packet_put_char(0); 2334 #endif /* WCOREDUMP */ 2335 packet_put_cstring(""); 2336 packet_put_cstring(""); 2337 packet_send(); 2338 } else { 2339 /* Some weird exit cause. Just exit. */ 2340 packet_disconnect("wait returned status %04x.", status); 2341 } 2342 2343 /* disconnect channel */ 2344 debug("%s: release channel %d", __func__, s->chanid); 2345 2346 /* 2347 * Adjust cleanup callback attachment to send close messages when 2348 * the channel gets EOF. The session will be then be closed 2349 * by session_close_by_channel when the childs close their fds. 2350 */ 2351 channel_register_cleanup(ssh, c->self, session_close_by_channel, 1); 2352 2353 /* 2354 * emulate a write failure with 'chan_write_failed', nobody will be 2355 * interested in data we write. 2356 * Note that we must not call 'chan_read_failed', since there could 2357 * be some more data waiting in the pipe. 2358 */ 2359 if (c->ostate != CHAN_OUTPUT_CLOSED) 2360 chan_write_failed(ssh, c); 2361 } 2362 2363 void 2364 session_close(struct ssh *ssh, Session *s) 2365 { 2366 u_int i; 2367 2368 verbose("Close session: user %s from %.200s port %d id %d", 2369 s->pw->pw_name, 2370 ssh_remote_ipaddr(ssh), 2371 ssh_remote_port(ssh), 2372 s->self); 2373 2374 if (s->ttyfd != -1) 2375 session_pty_cleanup(s); 2376 free(s->term); 2377 free(s->display); 2378 free(s->x11_chanids); 2379 free(s->auth_display); 2380 free(s->auth_data); 2381 free(s->auth_proto); 2382 free(s->subsys); 2383 if (s->env != NULL) { 2384 for (i = 0; i < s->num_env; i++) { 2385 free(s->env[i].name); 2386 free(s->env[i].val); 2387 } 2388 free(s->env); 2389 } 2390 session_proctitle(s); 2391 session_unused(s->self); 2392 } 2393 2394 void 2395 session_close_by_pid(struct ssh *ssh, pid_t pid, int status) 2396 { 2397 Session *s = session_by_pid(pid); 2398 if (s == NULL) { 2399 debug("%s: no session for pid %ld", __func__, (long)pid); 2400 return; 2401 } 2402 if (s->chanid != -1) 2403 session_exit_message(ssh, s, status); 2404 if (s->ttyfd != -1) 2405 session_pty_cleanup(s); 2406 s->pid = 0; 2407 } 2408 2409 /* 2410 * this is called when a channel dies before 2411 * the session 'child' itself dies 2412 */ 2413 void 2414 session_close_by_channel(struct ssh *ssh, int id, void *arg) 2415 { 2416 Session *s = session_by_channel(id); 2417 u_int i; 2418 2419 if (s == NULL) { 2420 debug("%s: no session for id %d", __func__, id); 2421 return; 2422 } 2423 debug("%s: channel %d child %ld", __func__, id, (long)s->pid); 2424 if (s->pid != 0) { 2425 debug("%s: channel %d: has child", __func__, id); 2426 /* 2427 * delay detach of session, but release pty, since 2428 * the fd's to the child are already closed 2429 */ 2430 if (s->ttyfd != -1) 2431 session_pty_cleanup(s); 2432 return; 2433 } 2434 /* detach by removing callback */ 2435 channel_cancel_cleanup(ssh, s->chanid); 2436 2437 /* Close any X11 listeners associated with this session */ 2438 if (s->x11_chanids != NULL) { 2439 for (i = 0; s->x11_chanids[i] != -1; i++) { 2440 session_close_x11(ssh, s->x11_chanids[i]); 2441 s->x11_chanids[i] = -1; 2442 } 2443 } 2444 2445 s->chanid = -1; 2446 session_close(ssh, s); 2447 } 2448 2449 void 2450 session_destroy_all(struct ssh *ssh, void (*closefunc)(Session *)) 2451 { 2452 int i; 2453 for (i = 0; i < sessions_nalloc; i++) { 2454 Session *s = &sessions[i]; 2455 if (s->used) { 2456 if (closefunc != NULL) 2457 closefunc(s); 2458 else 2459 session_close(ssh, s); 2460 } 2461 } 2462 } 2463 2464 static char * 2465 session_tty_list(void) 2466 { 2467 static char buf[1024]; 2468 int i; 2469 char *cp; 2470 2471 buf[0] = '\0'; 2472 for (i = 0; i < sessions_nalloc; i++) { 2473 Session *s = &sessions[i]; 2474 if (s->used && s->ttyfd != -1) { 2475 2476 if (strncmp(s->tty, "/dev/", 5) != 0) { 2477 cp = strrchr(s->tty, '/'); 2478 cp = (cp == NULL) ? s->tty : cp + 1; 2479 } else 2480 cp = s->tty + 5; 2481 2482 if (buf[0] != '\0') 2483 strlcat(buf, ",", sizeof buf); 2484 strlcat(buf, cp, sizeof buf); 2485 } 2486 } 2487 if (buf[0] == '\0') 2488 strlcpy(buf, "notty", sizeof buf); 2489 return buf; 2490 } 2491 2492 void 2493 session_proctitle(Session *s) 2494 { 2495 if (s->pw == NULL) 2496 error("no user for session %d", s->self); 2497 else 2498 setproctitle("%s@%s", s->pw->pw_name, session_tty_list()); 2499 } 2500 2501 int 2502 session_setup_x11fwd(struct ssh *ssh, Session *s) 2503 { 2504 struct stat st; 2505 char display[512], auth_display[512]; 2506 char hostname[NI_MAXHOST]; 2507 u_int i; 2508 2509 if (!auth_opts->permit_x11_forwarding_flag) { 2510 packet_send_debug("X11 forwarding disabled by key options."); 2511 return 0; 2512 } 2513 if (!options.x11_forwarding) { 2514 debug("X11 forwarding disabled in server configuration file."); 2515 return 0; 2516 } 2517 if (options.xauth_location == NULL || 2518 (stat(options.xauth_location, &st) == -1)) { 2519 packet_send_debug("No xauth program; cannot forward X11."); 2520 return 0; 2521 } 2522 if (s->display != NULL) { 2523 debug("X11 display already set."); 2524 return 0; 2525 } 2526 if (x11_create_display_inet(ssh, options.x11_display_offset, 2527 options.x11_use_localhost, s->single_connection, 2528 &s->display_number, &s->x11_chanids) == -1) { 2529 debug("x11_create_display_inet failed."); 2530 return 0; 2531 } 2532 for (i = 0; s->x11_chanids[i] != -1; i++) { 2533 channel_register_cleanup(ssh, s->x11_chanids[i], 2534 session_close_single_x11, 0); 2535 } 2536 2537 /* Set up a suitable value for the DISPLAY variable. */ 2538 if (gethostname(hostname, sizeof(hostname)) < 0) 2539 fatal("gethostname: %.100s", strerror(errno)); 2540 /* 2541 * auth_display must be used as the displayname when the 2542 * authorization entry is added with xauth(1). This will be 2543 * different than the DISPLAY string for localhost displays. 2544 */ 2545 if (options.x11_use_localhost) { 2546 snprintf(display, sizeof display, "localhost:%u.%u", 2547 s->display_number, s->screen); 2548 snprintf(auth_display, sizeof auth_display, "unix:%u.%u", 2549 s->display_number, s->screen); 2550 s->display = xstrdup(display); 2551 s->auth_display = xstrdup(auth_display); 2552 } else { 2553 #ifdef IPADDR_IN_DISPLAY 2554 struct hostent *he; 2555 struct in_addr my_addr; 2556 2557 he = gethostbyname(hostname); 2558 if (he == NULL) { 2559 error("Can't get IP address for X11 DISPLAY."); 2560 packet_send_debug("Can't get IP address for X11 DISPLAY."); 2561 return 0; 2562 } 2563 memcpy(&my_addr, he->h_addr_list[0], sizeof(struct in_addr)); 2564 snprintf(display, sizeof display, "%.50s:%u.%u", inet_ntoa(my_addr), 2565 s->display_number, s->screen); 2566 #else 2567 snprintf(display, sizeof display, "%.400s:%u.%u", hostname, 2568 s->display_number, s->screen); 2569 #endif 2570 s->display = xstrdup(display); 2571 s->auth_display = xstrdup(display); 2572 } 2573 2574 return 1; 2575 } 2576 2577 static void 2578 do_authenticated2(struct ssh *ssh, Authctxt *authctxt) 2579 { 2580 server_loop2(ssh, authctxt); 2581 } 2582 2583 void 2584 do_cleanup(struct ssh *ssh, Authctxt *authctxt) 2585 { 2586 static int called = 0; 2587 2588 debug("do_cleanup"); 2589 2590 /* no cleanup if we're in the child for login shell */ 2591 if (is_child) 2592 return; 2593 2594 /* avoid double cleanup */ 2595 if (called) 2596 return; 2597 called = 1; 2598 2599 if (authctxt == NULL) 2600 return; 2601 2602 #ifdef USE_PAM 2603 if (options.use_pam) { 2604 sshpam_cleanup(); 2605 sshpam_thread_cleanup(); 2606 } 2607 #endif 2608 2609 if (!authctxt->authenticated) 2610 return; 2611 2612 #ifdef KRB5 2613 if (options.kerberos_ticket_cleanup && 2614 authctxt->krb5_ctx) 2615 krb5_cleanup_proc(authctxt); 2616 #endif 2617 2618 #ifdef GSSAPI 2619 if (options.gss_cleanup_creds) 2620 ssh_gssapi_cleanup_creds(); 2621 #endif 2622 2623 /* remove agent socket */ 2624 auth_sock_cleanup_proc(authctxt->pw); 2625 2626 /* remove userauth info */ 2627 if (auth_info_file != NULL) { 2628 temporarily_use_uid(authctxt->pw); 2629 unlink(auth_info_file); 2630 restore_uid(); 2631 free(auth_info_file); 2632 auth_info_file = NULL; 2633 } 2634 2635 /* 2636 * Cleanup ptys/utmp only if privsep is disabled, 2637 * or if running in monitor. 2638 */ 2639 if (!use_privsep || mm_is_monitor()) 2640 session_destroy_all(ssh, session_pty_cleanup2); 2641 } 2642 2643 /* Return a name for the remote host that fits inside utmp_size */ 2644 2645 const char * 2646 session_get_remote_name_or_ip(struct ssh *ssh, u_int utmp_size, int use_dns) 2647 { 2648 const char *remote = ""; 2649 2650 if (utmp_size > 0) 2651 remote = auth_get_canonical_hostname(ssh, use_dns); 2652 if (utmp_size == 0 || strlen(remote) > utmp_size) 2653 remote = ssh_remote_ipaddr(ssh); 2654 return remote; 2655 } 2656 2657