1 /* $OpenBSD: session.c,v 1.307 2018/10/04 00:10:11 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 "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 s->forced = 0; 710 if (forced != NULL) { 711 s->forced = 1; 712 if (IS_INTERNAL_SFTP(command)) { 713 s->is_subsystem = s->is_subsystem ? 714 SUBSYSTEM_INT_SFTP : SUBSYSTEM_INT_SFTP_ERROR; 715 } else if (s->is_subsystem) 716 s->is_subsystem = SUBSYSTEM_EXT; 717 snprintf(session_type, sizeof(session_type), 718 "forced-command %s '%.900s'", forced, command); 719 } else if (s->is_subsystem) { 720 snprintf(session_type, sizeof(session_type), 721 "subsystem '%.900s'", s->subsys); 722 } else if (command == NULL) { 723 snprintf(session_type, sizeof(session_type), "shell"); 724 } else { 725 /* NB. we don't log unforced commands to preserve privacy */ 726 snprintf(session_type, sizeof(session_type), "command"); 727 } 728 729 if (s->ttyfd != -1) { 730 tty = s->tty; 731 if (strncmp(tty, "/dev/", 5) == 0) 732 tty += 5; 733 } 734 735 verbose("Starting session: %s%s%s for %s from %.200s port %d id %d", 736 session_type, 737 tty == NULL ? "" : " on ", 738 tty == NULL ? "" : tty, 739 s->pw->pw_name, 740 ssh_remote_ipaddr(ssh), 741 ssh_remote_port(ssh), 742 s->self); 743 744 #ifdef SSH_AUDIT_EVENTS 745 if (command != NULL) 746 PRIVSEP(audit_run_command(command)); 747 else if (s->ttyfd == -1) { 748 char *shell = s->pw->pw_shell; 749 750 if (shell[0] == '\0') /* empty shell means /bin/sh */ 751 shell =_PATH_BSHELL; 752 PRIVSEP(audit_run_command(shell)); 753 } 754 #endif 755 if (s->ttyfd != -1) 756 ret = do_exec_pty(ssh, s, command); 757 else 758 ret = do_exec_no_pty(ssh, s, command); 759 760 original_command = NULL; 761 762 /* 763 * Clear loginmsg: it's the child's responsibility to display 764 * it to the user, otherwise multiple sessions may accumulate 765 * multiple copies of the login messages. 766 */ 767 sshbuf_reset(loginmsg); 768 769 return ret; 770 } 771 772 /* administrative, login(1)-like work */ 773 void 774 do_login(struct ssh *ssh, Session *s, const char *command) 775 { 776 socklen_t fromlen; 777 struct sockaddr_storage from; 778 struct passwd * pw = s->pw; 779 pid_t pid = getpid(); 780 781 /* 782 * Get IP address of client. If the connection is not a socket, let 783 * the address be 0.0.0.0. 784 */ 785 memset(&from, 0, sizeof(from)); 786 fromlen = sizeof(from); 787 if (packet_connection_is_on_socket()) { 788 if (getpeername(packet_get_connection_in(), 789 (struct sockaddr *)&from, &fromlen) < 0) { 790 debug("getpeername: %.100s", strerror(errno)); 791 cleanup_exit(255); 792 } 793 } 794 795 /* Record that there was a login on that tty from the remote host. */ 796 if (!use_privsep) 797 record_login(pid, s->tty, pw->pw_name, pw->pw_uid, 798 session_get_remote_name_or_ip(ssh, utmp_len, 799 options.use_dns), 800 (struct sockaddr *)&from, fromlen); 801 802 #ifdef USE_PAM 803 /* 804 * If password change is needed, do it now. 805 * This needs to occur before the ~/.hushlogin check. 806 */ 807 if (options.use_pam && !use_privsep && s->authctxt->force_pwchange) { 808 display_loginmsg(); 809 do_pam_chauthtok(); 810 s->authctxt->force_pwchange = 0; 811 /* XXX - signal [net] parent to enable forwardings */ 812 } 813 #endif 814 815 if (check_quietlogin(s, command)) 816 return; 817 818 display_loginmsg(); 819 820 do_motd(); 821 } 822 823 /* 824 * Display the message of the day. 825 */ 826 void 827 do_motd(void) 828 { 829 FILE *f; 830 char buf[256]; 831 832 if (options.print_motd) { 833 #ifdef HAVE_LOGIN_CAP 834 f = fopen(login_getcapstr(lc, "welcome", "/etc/motd", 835 "/etc/motd"), "r"); 836 #else 837 f = fopen("/etc/motd", "r"); 838 #endif 839 if (f) { 840 while (fgets(buf, sizeof(buf), f)) 841 fputs(buf, stdout); 842 fclose(f); 843 } 844 } 845 } 846 847 848 /* 849 * Check for quiet login, either .hushlogin or command given. 850 */ 851 int 852 check_quietlogin(Session *s, const char *command) 853 { 854 char buf[256]; 855 struct passwd *pw = s->pw; 856 struct stat st; 857 858 /* Return 1 if .hushlogin exists or a command given. */ 859 if (command != NULL) 860 return 1; 861 snprintf(buf, sizeof(buf), "%.200s/.hushlogin", pw->pw_dir); 862 #ifdef HAVE_LOGIN_CAP 863 if (login_getcapbool(lc, "hushlogin", 0) || stat(buf, &st) >= 0) 864 return 1; 865 #else 866 if (stat(buf, &st) >= 0) 867 return 1; 868 #endif 869 return 0; 870 } 871 872 /* 873 * Reads environment variables from the given file and adds/overrides them 874 * into the environment. If the file does not exist, this does nothing. 875 * Otherwise, it must consist of empty lines, comments (line starts with '#') 876 * and assignments of the form name=value. No other forms are allowed. 877 * If whitelist is not NULL, then it is interpreted as a pattern list and 878 * only variable names that match it will be accepted. 879 */ 880 static void 881 read_environment_file(char ***env, u_int *envsize, 882 const char *filename, const char *whitelist) 883 { 884 FILE *f; 885 char *line = NULL, *cp, *value; 886 size_t linesize = 0; 887 u_int lineno = 0; 888 889 f = fopen(filename, "r"); 890 if (!f) 891 return; 892 893 while (getline(&line, &linesize, f) != -1) { 894 if (++lineno > 1000) 895 fatal("Too many lines in environment file %s", filename); 896 for (cp = line; *cp == ' ' || *cp == '\t'; cp++) 897 ; 898 if (!*cp || *cp == '#' || *cp == '\n') 899 continue; 900 901 cp[strcspn(cp, "\n")] = '\0'; 902 903 value = strchr(cp, '='); 904 if (value == NULL) { 905 fprintf(stderr, "Bad line %u in %.100s\n", lineno, 906 filename); 907 continue; 908 } 909 /* 910 * Replace the equals sign by nul, and advance value to 911 * the value string. 912 */ 913 *value = '\0'; 914 value++; 915 if (whitelist != NULL && 916 match_pattern_list(cp, whitelist, 0) != 1) 917 continue; 918 child_set_env(env, envsize, cp, value); 919 } 920 free(line); 921 fclose(f); 922 } 923 924 #ifdef HAVE_ETC_DEFAULT_LOGIN 925 /* 926 * Return named variable from specified environment, or NULL if not present. 927 */ 928 static char * 929 child_get_env(char **env, const char *name) 930 { 931 int i; 932 size_t len; 933 934 len = strlen(name); 935 for (i=0; env[i] != NULL; i++) 936 if (strncmp(name, env[i], len) == 0 && env[i][len] == '=') 937 return(env[i] + len + 1); 938 return NULL; 939 } 940 941 /* 942 * Read /etc/default/login. 943 * We pick up the PATH (or SUPATH for root) and UMASK. 944 */ 945 static void 946 read_etc_default_login(char ***env, u_int *envsize, uid_t uid) 947 { 948 char **tmpenv = NULL, *var; 949 u_int i, tmpenvsize = 0; 950 u_long mask; 951 952 /* 953 * We don't want to copy the whole file to the child's environment, 954 * so we use a temporary environment and copy the variables we're 955 * interested in. 956 */ 957 read_environment_file(&tmpenv, &tmpenvsize, "/etc/default/login", 958 options.permit_user_env_whitelist); 959 960 if (tmpenv == NULL) 961 return; 962 963 if (uid == 0) 964 var = child_get_env(tmpenv, "SUPATH"); 965 else 966 var = child_get_env(tmpenv, "PATH"); 967 if (var != NULL) 968 child_set_env(env, envsize, "PATH", var); 969 970 if ((var = child_get_env(tmpenv, "UMASK")) != NULL) 971 if (sscanf(var, "%5lo", &mask) == 1) 972 umask((mode_t)mask); 973 974 for (i = 0; tmpenv[i] != NULL; i++) 975 free(tmpenv[i]); 976 free(tmpenv); 977 } 978 #endif /* HAVE_ETC_DEFAULT_LOGIN */ 979 980 static void 981 copy_environment_blacklist(char **source, char ***env, u_int *envsize, 982 const char *blacklist) 983 { 984 char *var_name, *var_val; 985 int i; 986 987 if (source == NULL) 988 return; 989 990 for(i = 0; source[i] != NULL; i++) { 991 var_name = xstrdup(source[i]); 992 if ((var_val = strstr(var_name, "=")) == NULL) { 993 free(var_name); 994 continue; 995 } 996 *var_val++ = '\0'; 997 998 if (blacklist == NULL || 999 match_pattern_list(var_name, blacklist, 0) != 1) { 1000 debug3("Copy environment: %s=%s", var_name, var_val); 1001 child_set_env(env, envsize, var_name, var_val); 1002 } 1003 1004 free(var_name); 1005 } 1006 } 1007 1008 void 1009 copy_environment(char **source, char ***env, u_int *envsize) 1010 { 1011 copy_environment_blacklist(source, env, envsize, NULL); 1012 } 1013 1014 static char ** 1015 do_setup_env(struct ssh *ssh, Session *s, const char *shell) 1016 { 1017 char buf[256]; 1018 size_t n; 1019 u_int i, envsize; 1020 char *ocp, *cp, *value, **env, *laddr; 1021 struct passwd *pw = s->pw; 1022 #if !defined (HAVE_LOGIN_CAP) && !defined (HAVE_CYGWIN) 1023 char *path = NULL; 1024 #else 1025 extern char **environ; 1026 char **senv, **var, *val; 1027 #endif 1028 1029 /* Initialize the environment. */ 1030 envsize = 100; 1031 env = xcalloc(envsize, sizeof(char *)); 1032 env[0] = NULL; 1033 1034 #ifdef HAVE_CYGWIN 1035 /* 1036 * The Windows environment contains some setting which are 1037 * important for a running system. They must not be dropped. 1038 */ 1039 { 1040 char **p; 1041 1042 p = fetch_windows_environment(); 1043 copy_environment(p, &env, &envsize); 1044 free_windows_environment(p); 1045 } 1046 #endif 1047 1048 if (getenv("TZ")) 1049 child_set_env(&env, &envsize, "TZ", getenv("TZ")); 1050 1051 #ifdef GSSAPI 1052 /* Allow any GSSAPI methods that we've used to alter 1053 * the childs environment as they see fit 1054 */ 1055 ssh_gssapi_do_child(&env, &envsize); 1056 #endif 1057 1058 /* Set basic environment. */ 1059 for (i = 0; i < s->num_env; i++) 1060 child_set_env(&env, &envsize, s->env[i].name, s->env[i].val); 1061 1062 child_set_env(&env, &envsize, "USER", pw->pw_name); 1063 child_set_env(&env, &envsize, "LOGNAME", pw->pw_name); 1064 #ifdef _AIX 1065 child_set_env(&env, &envsize, "LOGIN", pw->pw_name); 1066 #endif 1067 child_set_env(&env, &envsize, "HOME", pw->pw_dir); 1068 snprintf(buf, sizeof buf, "%.200s/%.50s", _PATH_MAILDIR, pw->pw_name); 1069 child_set_env(&env, &envsize, "MAIL", buf); 1070 #ifdef HAVE_LOGIN_CAP 1071 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); 1072 child_set_env(&env, &envsize, "TERM", "su"); 1073 /* 1074 * Temporarily swap out our real environment with an empty one, 1075 * let setusercontext() apply any environment variables defined 1076 * for the user's login class, copy those variables to the child, 1077 * free the temporary environment, and restore the original. 1078 */ 1079 senv = environ; 1080 environ = xmalloc(sizeof(*environ)); 1081 *environ = NULL; 1082 (void)setusercontext(lc, pw, pw->pw_uid, LOGIN_SETENV|LOGIN_SETPATH); 1083 for (var = environ; *var != NULL; ++var) { 1084 if ((val = strchr(*var, '=')) != NULL) { 1085 *val++ = '\0'; 1086 child_set_env(&env, &envsize, *var, val); 1087 } 1088 free(*var); 1089 } 1090 free(environ); 1091 environ = senv; 1092 #else /* HAVE_LOGIN_CAP */ 1093 # ifndef HAVE_CYGWIN 1094 /* 1095 * There's no standard path on Windows. The path contains 1096 * important components pointing to the system directories, 1097 * needed for loading shared libraries. So the path better 1098 * remains intact here. 1099 */ 1100 # ifdef HAVE_ETC_DEFAULT_LOGIN 1101 read_etc_default_login(&env, &envsize, pw->pw_uid); 1102 path = child_get_env(env, "PATH"); 1103 # endif /* HAVE_ETC_DEFAULT_LOGIN */ 1104 if (path == NULL || *path == '\0') { 1105 child_set_env(&env, &envsize, "PATH", 1106 s->pw->pw_uid == 0 ? SUPERUSER_PATH : _PATH_STDPATH); 1107 } 1108 # endif /* HAVE_CYGWIN */ 1109 #endif /* HAVE_LOGIN_CAP */ 1110 1111 /* Normal systems set SHELL by default. */ 1112 child_set_env(&env, &envsize, "SHELL", shell); 1113 1114 if (s->term) 1115 child_set_env(&env, &envsize, "TERM", s->term); 1116 if (s->display) 1117 child_set_env(&env, &envsize, "DISPLAY", s->display); 1118 1119 /* 1120 * Since we clear KRB5CCNAME at startup, if it's set now then it 1121 * must have been set by a native authentication method (eg AIX or 1122 * SIA), so copy it to the child. 1123 */ 1124 { 1125 char *cp; 1126 1127 if ((cp = getenv("KRB5CCNAME")) != NULL) 1128 child_set_env(&env, &envsize, "KRB5CCNAME", cp); 1129 } 1130 1131 #ifdef _AIX 1132 { 1133 char *cp; 1134 1135 if ((cp = getenv("AUTHSTATE")) != NULL) 1136 child_set_env(&env, &envsize, "AUTHSTATE", cp); 1137 read_environment_file(&env, &envsize, "/etc/environment", 1138 options.permit_user_env_whitelist); 1139 } 1140 #endif 1141 #ifdef KRB5 1142 if (s->authctxt->krb5_ccname) 1143 child_set_env(&env, &envsize, "KRB5CCNAME", 1144 s->authctxt->krb5_ccname); 1145 #endif 1146 if (auth_sock_name != NULL) 1147 child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME, 1148 auth_sock_name); 1149 1150 1151 /* Set custom environment options from pubkey authentication. */ 1152 if (options.permit_user_env) { 1153 for (n = 0 ; n < auth_opts->nenv; n++) { 1154 ocp = xstrdup(auth_opts->env[n]); 1155 cp = strchr(ocp, '='); 1156 if (*cp == '=') { 1157 *cp = '\0'; 1158 /* Apply PermitUserEnvironment whitelist */ 1159 if (options.permit_user_env_whitelist == NULL || 1160 match_pattern_list(ocp, 1161 options.permit_user_env_whitelist, 0) == 1) 1162 child_set_env(&env, &envsize, 1163 ocp, cp + 1); 1164 } 1165 free(ocp); 1166 } 1167 } 1168 1169 /* read $HOME/.ssh/environment. */ 1170 if (options.permit_user_env) { 1171 snprintf(buf, sizeof buf, "%.200s/.ssh/environment", 1172 pw->pw_dir); 1173 read_environment_file(&env, &envsize, buf, 1174 options.permit_user_env_whitelist); 1175 } 1176 1177 #ifdef USE_PAM 1178 /* 1179 * Pull in any environment variables that may have 1180 * been set by PAM. 1181 */ 1182 if (options.use_pam) { 1183 char **p; 1184 1185 /* 1186 * Don't allow SSH_AUTH_INFO variables posted to PAM to leak 1187 * back into the environment. 1188 */ 1189 p = fetch_pam_child_environment(); 1190 copy_environment_blacklist(p, &env, &envsize, "SSH_AUTH_INFO*"); 1191 free_pam_environment(p); 1192 1193 p = fetch_pam_environment(); 1194 copy_environment_blacklist(p, &env, &envsize, "SSH_AUTH_INFO*"); 1195 free_pam_environment(p); 1196 } 1197 #endif /* USE_PAM */ 1198 1199 /* Environment specified by admin */ 1200 for (i = 0; i < options.num_setenv; i++) { 1201 cp = xstrdup(options.setenv[i]); 1202 if ((value = strchr(cp, '=')) == NULL) { 1203 /* shouldn't happen; vars are checked in servconf.c */ 1204 fatal("Invalid config SetEnv: %s", options.setenv[i]); 1205 } 1206 *value++ = '\0'; 1207 child_set_env(&env, &envsize, cp, value); 1208 } 1209 1210 /* SSH_CLIENT deprecated */ 1211 snprintf(buf, sizeof buf, "%.50s %d %d", 1212 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 1213 ssh_local_port(ssh)); 1214 child_set_env(&env, &envsize, "SSH_CLIENT", buf); 1215 1216 laddr = get_local_ipaddr(packet_get_connection_in()); 1217 snprintf(buf, sizeof buf, "%.50s %d %.50s %d", 1218 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 1219 laddr, ssh_local_port(ssh)); 1220 free(laddr); 1221 child_set_env(&env, &envsize, "SSH_CONNECTION", buf); 1222 1223 if (tun_fwd_ifnames != NULL) 1224 child_set_env(&env, &envsize, "SSH_TUNNEL", tun_fwd_ifnames); 1225 if (auth_info_file != NULL) 1226 child_set_env(&env, &envsize, "SSH_USER_AUTH", auth_info_file); 1227 if (s->ttyfd != -1) 1228 child_set_env(&env, &envsize, "SSH_TTY", s->tty); 1229 if (original_command) 1230 child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND", 1231 original_command); 1232 1233 if (debug_flag) { 1234 /* dump the environment */ 1235 fprintf(stderr, "Environment:\n"); 1236 for (i = 0; env[i]; i++) 1237 fprintf(stderr, " %.200s\n", env[i]); 1238 } 1239 return env; 1240 } 1241 1242 /* 1243 * Run $HOME/.ssh/rc, /etc/ssh/sshrc, or xauth (whichever is found 1244 * first in this order). 1245 */ 1246 static void 1247 do_rc_files(struct ssh *ssh, Session *s, const char *shell) 1248 { 1249 FILE *f = NULL; 1250 char cmd[1024]; 1251 int do_xauth; 1252 struct stat st; 1253 1254 do_xauth = 1255 s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL; 1256 1257 /* ignore _PATH_SSH_USER_RC for subsystems and admin forced commands */ 1258 if (!s->is_subsystem && options.adm_forced_command == NULL && 1259 auth_opts->permit_user_rc && options.permit_user_rc && 1260 stat(_PATH_SSH_USER_RC, &st) >= 0) { 1261 snprintf(cmd, sizeof cmd, "%s -c '%s %s'", 1262 shell, _PATH_BSHELL, _PATH_SSH_USER_RC); 1263 if (debug_flag) 1264 fprintf(stderr, "Running %s\n", cmd); 1265 f = popen(cmd, "w"); 1266 if (f) { 1267 if (do_xauth) 1268 fprintf(f, "%s %s\n", s->auth_proto, 1269 s->auth_data); 1270 pclose(f); 1271 } else 1272 fprintf(stderr, "Could not run %s\n", 1273 _PATH_SSH_USER_RC); 1274 } else if (stat(_PATH_SSH_SYSTEM_RC, &st) >= 0) { 1275 if (debug_flag) 1276 fprintf(stderr, "Running %s %s\n", _PATH_BSHELL, 1277 _PATH_SSH_SYSTEM_RC); 1278 f = popen(_PATH_BSHELL " " _PATH_SSH_SYSTEM_RC, "w"); 1279 if (f) { 1280 if (do_xauth) 1281 fprintf(f, "%s %s\n", s->auth_proto, 1282 s->auth_data); 1283 pclose(f); 1284 } else 1285 fprintf(stderr, "Could not run %s\n", 1286 _PATH_SSH_SYSTEM_RC); 1287 } else if (do_xauth && options.xauth_location != NULL) { 1288 /* Add authority data to .Xauthority if appropriate. */ 1289 if (debug_flag) { 1290 fprintf(stderr, 1291 "Running %.500s remove %.100s\n", 1292 options.xauth_location, s->auth_display); 1293 fprintf(stderr, 1294 "%.500s add %.100s %.100s %.100s\n", 1295 options.xauth_location, s->auth_display, 1296 s->auth_proto, s->auth_data); 1297 } 1298 snprintf(cmd, sizeof cmd, "%s -q -", 1299 options.xauth_location); 1300 f = popen(cmd, "w"); 1301 if (f) { 1302 fprintf(f, "remove %s\n", 1303 s->auth_display); 1304 fprintf(f, "add %s %s %s\n", 1305 s->auth_display, s->auth_proto, 1306 s->auth_data); 1307 pclose(f); 1308 } else { 1309 fprintf(stderr, "Could not run %s\n", 1310 cmd); 1311 } 1312 } 1313 } 1314 1315 static void 1316 do_nologin(struct passwd *pw) 1317 { 1318 FILE *f = NULL; 1319 const char *nl; 1320 char buf[1024], *def_nl = _PATH_NOLOGIN; 1321 struct stat sb; 1322 1323 #ifdef HAVE_LOGIN_CAP 1324 if (login_getcapbool(lc, "ignorenologin", 0) || pw->pw_uid == 0) 1325 return; 1326 nl = login_getcapstr(lc, "nologin", def_nl, def_nl); 1327 #else 1328 if (pw->pw_uid == 0) 1329 return; 1330 nl = def_nl; 1331 #endif 1332 if (stat(nl, &sb) == -1) 1333 return; 1334 1335 /* /etc/nologin exists. Print its contents if we can and exit. */ 1336 logit("User %.100s not allowed because %s exists", pw->pw_name, nl); 1337 if ((f = fopen(nl, "r")) != NULL) { 1338 while (fgets(buf, sizeof(buf), f)) 1339 fputs(buf, stderr); 1340 fclose(f); 1341 } 1342 exit(254); 1343 } 1344 1345 /* 1346 * Chroot into a directory after checking it for safety: all path components 1347 * must be root-owned directories with strict permissions. 1348 */ 1349 static void 1350 safely_chroot(const char *path, uid_t uid) 1351 { 1352 const char *cp; 1353 char component[PATH_MAX]; 1354 struct stat st; 1355 1356 if (*path != '/') 1357 fatal("chroot path does not begin at root"); 1358 if (strlen(path) >= sizeof(component)) 1359 fatal("chroot path too long"); 1360 1361 /* 1362 * Descend the path, checking that each component is a 1363 * root-owned directory with strict permissions. 1364 */ 1365 for (cp = path; cp != NULL;) { 1366 if ((cp = strchr(cp, '/')) == NULL) 1367 strlcpy(component, path, sizeof(component)); 1368 else { 1369 cp++; 1370 memcpy(component, path, cp - path); 1371 component[cp - path] = '\0'; 1372 } 1373 1374 debug3("%s: checking '%s'", __func__, component); 1375 1376 if (stat(component, &st) != 0) 1377 fatal("%s: stat(\"%s\"): %s", __func__, 1378 component, strerror(errno)); 1379 if (st.st_uid != 0 || (st.st_mode & 022) != 0) 1380 fatal("bad ownership or modes for chroot " 1381 "directory %s\"%s\"", 1382 cp == NULL ? "" : "component ", component); 1383 if (!S_ISDIR(st.st_mode)) 1384 fatal("chroot path %s\"%s\" is not a directory", 1385 cp == NULL ? "" : "component ", component); 1386 1387 } 1388 1389 if (chdir(path) == -1) 1390 fatal("Unable to chdir to chroot path \"%s\": " 1391 "%s", path, strerror(errno)); 1392 if (chroot(path) == -1) 1393 fatal("chroot(\"%s\"): %s", path, strerror(errno)); 1394 if (chdir("/") == -1) 1395 fatal("%s: chdir(/) after chroot: %s", 1396 __func__, strerror(errno)); 1397 verbose("Changed root directory to \"%s\"", path); 1398 } 1399 1400 /* Set login name, uid, gid, and groups. */ 1401 void 1402 do_setusercontext(struct passwd *pw) 1403 { 1404 char uidstr[32], *chroot_path, *tmp; 1405 1406 platform_setusercontext(pw); 1407 1408 if (platform_privileged_uidswap()) { 1409 #ifdef HAVE_LOGIN_CAP 1410 if (setusercontext(lc, pw, pw->pw_uid, 1411 (LOGIN_SETALL & ~(LOGIN_SETENV|LOGIN_SETPATH|LOGIN_SETUSER))) < 0) { 1412 perror("unable to set user context"); 1413 exit(1); 1414 } 1415 #else 1416 if (setlogin(pw->pw_name) < 0) 1417 error("setlogin failed: %s", strerror(errno)); 1418 if (setgid(pw->pw_gid) < 0) { 1419 perror("setgid"); 1420 exit(1); 1421 } 1422 /* Initialize the group list. */ 1423 if (initgroups(pw->pw_name, pw->pw_gid) < 0) { 1424 perror("initgroups"); 1425 exit(1); 1426 } 1427 endgrent(); 1428 #endif 1429 1430 platform_setusercontext_post_groups(pw); 1431 1432 if (!in_chroot && options.chroot_directory != NULL && 1433 strcasecmp(options.chroot_directory, "none") != 0) { 1434 tmp = tilde_expand_filename(options.chroot_directory, 1435 pw->pw_uid); 1436 snprintf(uidstr, sizeof(uidstr), "%llu", 1437 (unsigned long long)pw->pw_uid); 1438 chroot_path = percent_expand(tmp, "h", pw->pw_dir, 1439 "u", pw->pw_name, "U", uidstr, (char *)NULL); 1440 safely_chroot(chroot_path, pw->pw_uid); 1441 free(tmp); 1442 free(chroot_path); 1443 /* Make sure we don't attempt to chroot again */ 1444 free(options.chroot_directory); 1445 options.chroot_directory = NULL; 1446 in_chroot = 1; 1447 } 1448 1449 #ifdef HAVE_LOGIN_CAP 1450 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUSER) < 0) { 1451 perror("unable to set user context (setuser)"); 1452 exit(1); 1453 } 1454 /* 1455 * FreeBSD's setusercontext() will not apply the user's 1456 * own umask setting unless running with the user's UID. 1457 */ 1458 (void) setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUMASK); 1459 #else 1460 # ifdef USE_LIBIAF 1461 /* 1462 * In a chroot environment, the set_id() will always fail; 1463 * typically because of the lack of necessary authentication 1464 * services and runtime such as ./usr/lib/libiaf.so, 1465 * ./usr/lib/libpam.so.1, and ./etc/passwd We skip it in the 1466 * internal sftp chroot case. We'll lose auditing and ACLs but 1467 * permanently_set_uid will take care of the rest. 1468 */ 1469 if (!in_chroot && set_id(pw->pw_name) != 0) 1470 fatal("set_id(%s) Failed", pw->pw_name); 1471 # endif /* USE_LIBIAF */ 1472 /* Permanently switch to the desired uid. */ 1473 permanently_set_uid(pw); 1474 #endif 1475 } else if (options.chroot_directory != NULL && 1476 strcasecmp(options.chroot_directory, "none") != 0) { 1477 fatal("server lacks privileges to chroot to ChrootDirectory"); 1478 } 1479 1480 if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) 1481 fatal("Failed to set uids to %u.", (u_int) pw->pw_uid); 1482 } 1483 1484 static void 1485 do_pwchange(Session *s) 1486 { 1487 fflush(NULL); 1488 fprintf(stderr, "WARNING: Your password has expired.\n"); 1489 if (s->ttyfd != -1) { 1490 fprintf(stderr, 1491 "You must change your password now and login again!\n"); 1492 #ifdef WITH_SELINUX 1493 setexeccon(NULL); 1494 #endif 1495 #ifdef PASSWD_NEEDS_USERNAME 1496 execl(_PATH_PASSWD_PROG, "passwd", s->pw->pw_name, 1497 (char *)NULL); 1498 #else 1499 execl(_PATH_PASSWD_PROG, "passwd", (char *)NULL); 1500 #endif 1501 perror("passwd"); 1502 } else { 1503 fprintf(stderr, 1504 "Password change required but no TTY available.\n"); 1505 } 1506 exit(1); 1507 } 1508 1509 static void 1510 child_close_fds(struct ssh *ssh) 1511 { 1512 extern int auth_sock; 1513 1514 if (auth_sock != -1) { 1515 close(auth_sock); 1516 auth_sock = -1; 1517 } 1518 1519 if (packet_get_connection_in() == packet_get_connection_out()) 1520 close(packet_get_connection_in()); 1521 else { 1522 close(packet_get_connection_in()); 1523 close(packet_get_connection_out()); 1524 } 1525 /* 1526 * Close all descriptors related to channels. They will still remain 1527 * open in the parent. 1528 */ 1529 /* XXX better use close-on-exec? -markus */ 1530 channel_close_all(ssh); 1531 1532 /* 1533 * Close any extra file descriptors. Note that there may still be 1534 * descriptors left by system functions. They will be closed later. 1535 */ 1536 endpwent(); 1537 1538 /* 1539 * Close any extra open file descriptors so that we don't have them 1540 * hanging around in clients. Note that we want to do this after 1541 * initgroups, because at least on Solaris 2.3 it leaves file 1542 * descriptors open. 1543 */ 1544 closefrom(STDERR_FILENO + 1); 1545 } 1546 1547 /* 1548 * Performs common processing for the child, such as setting up the 1549 * environment, closing extra file descriptors, setting the user and group 1550 * ids, and executing the command or shell. 1551 */ 1552 #define ARGV_MAX 10 1553 void 1554 do_child(struct ssh *ssh, Session *s, const char *command) 1555 { 1556 extern char **environ; 1557 char **env; 1558 char *argv[ARGV_MAX]; 1559 const char *shell, *shell0; 1560 struct passwd *pw = s->pw; 1561 int r = 0; 1562 1563 /* remove hostkey from the child's memory */ 1564 destroy_sensitive_data(); 1565 packet_clear_keys(); 1566 1567 /* Force a password change */ 1568 if (s->authctxt->force_pwchange) { 1569 do_setusercontext(pw); 1570 child_close_fds(ssh); 1571 do_pwchange(s); 1572 exit(1); 1573 } 1574 1575 /* 1576 * Login(1) does this as well, and it needs uid 0 for the "-h" 1577 * switch, so we let login(1) to this for us. 1578 */ 1579 #ifdef HAVE_OSF_SIA 1580 session_setup_sia(pw, s->ttyfd == -1 ? NULL : s->tty); 1581 if (!check_quietlogin(s, command)) 1582 do_motd(); 1583 #else /* HAVE_OSF_SIA */ 1584 /* When PAM is enabled we rely on it to do the nologin check */ 1585 if (!options.use_pam) 1586 do_nologin(pw); 1587 do_setusercontext(pw); 1588 /* 1589 * PAM session modules in do_setusercontext may have 1590 * generated messages, so if this in an interactive 1591 * login then display them too. 1592 */ 1593 if (!check_quietlogin(s, command)) 1594 display_loginmsg(); 1595 #endif /* HAVE_OSF_SIA */ 1596 1597 #ifdef USE_PAM 1598 if (options.use_pam && !is_pam_session_open()) { 1599 debug3("PAM session not opened, exiting"); 1600 display_loginmsg(); 1601 exit(254); 1602 } 1603 #endif 1604 1605 /* 1606 * Get the shell from the password data. An empty shell field is 1607 * legal, and means /bin/sh. 1608 */ 1609 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; 1610 1611 /* 1612 * Make sure $SHELL points to the shell from the password file, 1613 * even if shell is overridden from login.conf 1614 */ 1615 env = do_setup_env(ssh, s, shell); 1616 1617 #ifdef HAVE_LOGIN_CAP 1618 shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell); 1619 #endif 1620 1621 /* 1622 * Close the connection descriptors; note that this is the child, and 1623 * the server will still have the socket open, and it is important 1624 * that we do not shutdown it. Note that the descriptors cannot be 1625 * closed before building the environment, as we call 1626 * ssh_remote_ipaddr there. 1627 */ 1628 child_close_fds(ssh); 1629 1630 /* 1631 * Must take new environment into use so that .ssh/rc, 1632 * /etc/ssh/sshrc and xauth are run in the proper environment. 1633 */ 1634 environ = env; 1635 1636 #if defined(KRB5) && defined(USE_AFS) 1637 /* 1638 * At this point, we check to see if AFS is active and if we have 1639 * a valid Kerberos 5 TGT. If so, it seems like a good idea to see 1640 * if we can (and need to) extend the ticket into an AFS token. If 1641 * we don't do this, we run into potential problems if the user's 1642 * home directory is in AFS and it's not world-readable. 1643 */ 1644 1645 if (options.kerberos_get_afs_token && k_hasafs() && 1646 (s->authctxt->krb5_ctx != NULL)) { 1647 char cell[64]; 1648 1649 debug("Getting AFS token"); 1650 1651 k_setpag(); 1652 1653 if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0) 1654 krb5_afslog(s->authctxt->krb5_ctx, 1655 s->authctxt->krb5_fwd_ccache, cell, NULL); 1656 1657 krb5_afslog_home(s->authctxt->krb5_ctx, 1658 s->authctxt->krb5_fwd_ccache, NULL, NULL, pw->pw_dir); 1659 } 1660 #endif 1661 1662 /* Change current directory to the user's home directory. */ 1663 if (chdir(pw->pw_dir) < 0) { 1664 /* Suppress missing homedir warning for chroot case */ 1665 #ifdef HAVE_LOGIN_CAP 1666 r = login_getcapbool(lc, "requirehome", 0); 1667 #endif 1668 if (r || !in_chroot) { 1669 fprintf(stderr, "Could not chdir to home " 1670 "directory %s: %s\n", pw->pw_dir, 1671 strerror(errno)); 1672 } 1673 if (r) 1674 exit(1); 1675 } 1676 1677 closefrom(STDERR_FILENO + 1); 1678 1679 do_rc_files(ssh, s, shell); 1680 1681 /* restore SIGPIPE for child */ 1682 signal(SIGPIPE, SIG_DFL); 1683 1684 if (s->is_subsystem == SUBSYSTEM_INT_SFTP_ERROR) { 1685 printf("This service allows sftp connections only.\n"); 1686 fflush(NULL); 1687 exit(1); 1688 } else if (s->is_subsystem == SUBSYSTEM_INT_SFTP) { 1689 extern int optind, optreset; 1690 int i; 1691 char *p, *args; 1692 1693 setproctitle("%s@%s", s->pw->pw_name, INTERNAL_SFTP_NAME); 1694 args = xstrdup(command ? command : "sftp-server"); 1695 for (i = 0, (p = strtok(args, " ")); p; (p = strtok(NULL, " "))) 1696 if (i < ARGV_MAX - 1) 1697 argv[i++] = p; 1698 argv[i] = NULL; 1699 optind = optreset = 1; 1700 __progname = argv[0]; 1701 #ifdef WITH_SELINUX 1702 ssh_selinux_change_context("sftpd_t"); 1703 #endif 1704 exit(sftp_server_main(i, argv, s->pw)); 1705 } 1706 1707 fflush(NULL); 1708 1709 /* Get the last component of the shell name. */ 1710 if ((shell0 = strrchr(shell, '/')) != NULL) 1711 shell0++; 1712 else 1713 shell0 = shell; 1714 1715 /* 1716 * If we have no command, execute the shell. In this case, the shell 1717 * name to be passed in argv[0] is preceded by '-' to indicate that 1718 * this is a login shell. 1719 */ 1720 if (!command) { 1721 char argv0[256]; 1722 1723 /* Start the shell. Set initial character to '-'. */ 1724 argv0[0] = '-'; 1725 1726 if (strlcpy(argv0 + 1, shell0, sizeof(argv0) - 1) 1727 >= sizeof(argv0) - 1) { 1728 errno = EINVAL; 1729 perror(shell); 1730 exit(1); 1731 } 1732 1733 /* Execute the shell. */ 1734 argv[0] = argv0; 1735 argv[1] = NULL; 1736 execve(shell, argv, env); 1737 1738 /* Executing the shell failed. */ 1739 perror(shell); 1740 exit(1); 1741 } 1742 /* 1743 * Execute the command using the user's shell. This uses the -c 1744 * option to execute the command. 1745 */ 1746 argv[0] = (char *) shell0; 1747 argv[1] = "-c"; 1748 argv[2] = (char *) command; 1749 argv[3] = NULL; 1750 execve(shell, argv, env); 1751 perror(shell); 1752 exit(1); 1753 } 1754 1755 void 1756 session_unused(int id) 1757 { 1758 debug3("%s: session id %d unused", __func__, id); 1759 if (id >= options.max_sessions || 1760 id >= sessions_nalloc) { 1761 fatal("%s: insane session id %d (max %d nalloc %d)", 1762 __func__, id, options.max_sessions, sessions_nalloc); 1763 } 1764 memset(&sessions[id], 0, sizeof(*sessions)); 1765 sessions[id].self = id; 1766 sessions[id].used = 0; 1767 sessions[id].chanid = -1; 1768 sessions[id].ptyfd = -1; 1769 sessions[id].ttyfd = -1; 1770 sessions[id].ptymaster = -1; 1771 sessions[id].x11_chanids = NULL; 1772 sessions[id].next_unused = sessions_first_unused; 1773 sessions_first_unused = id; 1774 } 1775 1776 Session * 1777 session_new(void) 1778 { 1779 Session *s, *tmp; 1780 1781 if (sessions_first_unused == -1) { 1782 if (sessions_nalloc >= options.max_sessions) 1783 return NULL; 1784 debug2("%s: allocate (allocated %d max %d)", 1785 __func__, sessions_nalloc, options.max_sessions); 1786 tmp = xrecallocarray(sessions, sessions_nalloc, 1787 sessions_nalloc + 1, sizeof(*sessions)); 1788 if (tmp == NULL) { 1789 error("%s: cannot allocate %d sessions", 1790 __func__, sessions_nalloc + 1); 1791 return NULL; 1792 } 1793 sessions = tmp; 1794 session_unused(sessions_nalloc++); 1795 } 1796 1797 if (sessions_first_unused >= sessions_nalloc || 1798 sessions_first_unused < 0) { 1799 fatal("%s: insane first_unused %d max %d nalloc %d", 1800 __func__, sessions_first_unused, options.max_sessions, 1801 sessions_nalloc); 1802 } 1803 1804 s = &sessions[sessions_first_unused]; 1805 if (s->used) { 1806 fatal("%s: session %d already used", 1807 __func__, sessions_first_unused); 1808 } 1809 sessions_first_unused = s->next_unused; 1810 s->used = 1; 1811 s->next_unused = -1; 1812 debug("session_new: session %d", s->self); 1813 1814 return s; 1815 } 1816 1817 static void 1818 session_dump(void) 1819 { 1820 int i; 1821 for (i = 0; i < sessions_nalloc; i++) { 1822 Session *s = &sessions[i]; 1823 1824 debug("dump: used %d next_unused %d session %d %p " 1825 "channel %d pid %ld", 1826 s->used, 1827 s->next_unused, 1828 s->self, 1829 s, 1830 s->chanid, 1831 (long)s->pid); 1832 } 1833 } 1834 1835 int 1836 session_open(Authctxt *authctxt, int chanid) 1837 { 1838 Session *s = session_new(); 1839 debug("session_open: channel %d", chanid); 1840 if (s == NULL) { 1841 error("no more sessions"); 1842 return 0; 1843 } 1844 s->authctxt = authctxt; 1845 s->pw = authctxt->pw; 1846 if (s->pw == NULL || !authctxt->valid) 1847 fatal("no user for session %d", s->self); 1848 debug("session_open: session %d: link with channel %d", s->self, chanid); 1849 s->chanid = chanid; 1850 return 1; 1851 } 1852 1853 Session * 1854 session_by_tty(char *tty) 1855 { 1856 int i; 1857 for (i = 0; i < sessions_nalloc; i++) { 1858 Session *s = &sessions[i]; 1859 if (s->used && s->ttyfd != -1 && strcmp(s->tty, tty) == 0) { 1860 debug("session_by_tty: session %d tty %s", i, tty); 1861 return s; 1862 } 1863 } 1864 debug("session_by_tty: unknown tty %.100s", tty); 1865 session_dump(); 1866 return NULL; 1867 } 1868 1869 static Session * 1870 session_by_channel(int id) 1871 { 1872 int i; 1873 for (i = 0; i < sessions_nalloc; i++) { 1874 Session *s = &sessions[i]; 1875 if (s->used && s->chanid == id) { 1876 debug("session_by_channel: session %d channel %d", 1877 i, id); 1878 return s; 1879 } 1880 } 1881 debug("session_by_channel: unknown channel %d", id); 1882 session_dump(); 1883 return NULL; 1884 } 1885 1886 static Session * 1887 session_by_x11_channel(int id) 1888 { 1889 int i, j; 1890 1891 for (i = 0; i < sessions_nalloc; i++) { 1892 Session *s = &sessions[i]; 1893 1894 if (s->x11_chanids == NULL || !s->used) 1895 continue; 1896 for (j = 0; s->x11_chanids[j] != -1; j++) { 1897 if (s->x11_chanids[j] == id) { 1898 debug("session_by_x11_channel: session %d " 1899 "channel %d", s->self, id); 1900 return s; 1901 } 1902 } 1903 } 1904 debug("session_by_x11_channel: unknown channel %d", id); 1905 session_dump(); 1906 return NULL; 1907 } 1908 1909 static Session * 1910 session_by_pid(pid_t pid) 1911 { 1912 int i; 1913 debug("session_by_pid: pid %ld", (long)pid); 1914 for (i = 0; i < sessions_nalloc; i++) { 1915 Session *s = &sessions[i]; 1916 if (s->used && s->pid == pid) 1917 return s; 1918 } 1919 error("session_by_pid: unknown pid %ld", (long)pid); 1920 session_dump(); 1921 return NULL; 1922 } 1923 1924 static int 1925 session_window_change_req(struct ssh *ssh, Session *s) 1926 { 1927 s->col = packet_get_int(); 1928 s->row = packet_get_int(); 1929 s->xpixel = packet_get_int(); 1930 s->ypixel = packet_get_int(); 1931 packet_check_eom(); 1932 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 1933 return 1; 1934 } 1935 1936 static int 1937 session_pty_req(struct ssh *ssh, Session *s) 1938 { 1939 u_int len; 1940 1941 if (!auth_opts->permit_pty_flag || !options.permit_tty) { 1942 debug("Allocating a pty not permitted for this connection."); 1943 return 0; 1944 } 1945 if (s->ttyfd != -1) { 1946 packet_disconnect("Protocol error: you already have a pty."); 1947 return 0; 1948 } 1949 1950 s->term = packet_get_string(&len); 1951 s->col = packet_get_int(); 1952 s->row = packet_get_int(); 1953 s->xpixel = packet_get_int(); 1954 s->ypixel = packet_get_int(); 1955 1956 if (strcmp(s->term, "") == 0) { 1957 free(s->term); 1958 s->term = NULL; 1959 } 1960 1961 /* Allocate a pty and open it. */ 1962 debug("Allocating pty."); 1963 if (!PRIVSEP(pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, 1964 sizeof(s->tty)))) { 1965 free(s->term); 1966 s->term = NULL; 1967 s->ptyfd = -1; 1968 s->ttyfd = -1; 1969 error("session_pty_req: session %d alloc failed", s->self); 1970 return 0; 1971 } 1972 debug("session_pty_req: session %d alloc %s", s->self, s->tty); 1973 1974 ssh_tty_parse_modes(ssh, s->ttyfd); 1975 1976 if (!use_privsep) 1977 pty_setowner(s->pw, s->tty); 1978 1979 /* Set window size from the packet. */ 1980 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 1981 1982 packet_check_eom(); 1983 session_proctitle(s); 1984 return 1; 1985 } 1986 1987 static int 1988 session_subsystem_req(struct ssh *ssh, Session *s) 1989 { 1990 struct stat st; 1991 u_int len; 1992 int success = 0; 1993 char *prog, *cmd; 1994 u_int i; 1995 1996 s->subsys = packet_get_string(&len); 1997 packet_check_eom(); 1998 debug2("subsystem request for %.100s by user %s", s->subsys, 1999 s->pw->pw_name); 2000 2001 for (i = 0; i < options.num_subsystems; i++) { 2002 if (strcmp(s->subsys, options.subsystem_name[i]) == 0) { 2003 prog = options.subsystem_command[i]; 2004 cmd = options.subsystem_args[i]; 2005 if (strcmp(INTERNAL_SFTP_NAME, prog) == 0) { 2006 s->is_subsystem = SUBSYSTEM_INT_SFTP; 2007 debug("subsystem: %s", prog); 2008 } else { 2009 if (stat(prog, &st) < 0) 2010 debug("subsystem: cannot stat %s: %s", 2011 prog, strerror(errno)); 2012 s->is_subsystem = SUBSYSTEM_EXT; 2013 debug("subsystem: exec() %s", cmd); 2014 } 2015 success = do_exec(ssh, s, cmd) == 0; 2016 break; 2017 } 2018 } 2019 2020 if (!success) 2021 logit("subsystem request for %.100s by user %s failed, " 2022 "subsystem not found", s->subsys, s->pw->pw_name); 2023 2024 return success; 2025 } 2026 2027 static int 2028 session_x11_req(struct ssh *ssh, Session *s) 2029 { 2030 int success; 2031 2032 if (s->auth_proto != NULL || s->auth_data != NULL) { 2033 error("session_x11_req: session %d: " 2034 "x11 forwarding already active", s->self); 2035 return 0; 2036 } 2037 s->single_connection = packet_get_char(); 2038 s->auth_proto = packet_get_string(NULL); 2039 s->auth_data = packet_get_string(NULL); 2040 s->screen = packet_get_int(); 2041 packet_check_eom(); 2042 2043 if (xauth_valid_string(s->auth_proto) && 2044 xauth_valid_string(s->auth_data)) 2045 success = session_setup_x11fwd(ssh, s); 2046 else { 2047 success = 0; 2048 error("Invalid X11 forwarding data"); 2049 } 2050 if (!success) { 2051 free(s->auth_proto); 2052 free(s->auth_data); 2053 s->auth_proto = NULL; 2054 s->auth_data = NULL; 2055 } 2056 return success; 2057 } 2058 2059 static int 2060 session_shell_req(struct ssh *ssh, Session *s) 2061 { 2062 packet_check_eom(); 2063 return do_exec(ssh, s, NULL) == 0; 2064 } 2065 2066 static int 2067 session_exec_req(struct ssh *ssh, Session *s) 2068 { 2069 u_int len, success; 2070 2071 char *command = packet_get_string(&len); 2072 packet_check_eom(); 2073 success = do_exec(ssh, s, command) == 0; 2074 free(command); 2075 return success; 2076 } 2077 2078 static int 2079 session_break_req(struct ssh *ssh, Session *s) 2080 { 2081 2082 packet_get_int(); /* ignored */ 2083 packet_check_eom(); 2084 2085 if (s->ptymaster == -1 || tcsendbreak(s->ptymaster, 0) < 0) 2086 return 0; 2087 return 1; 2088 } 2089 2090 static int 2091 session_env_req(struct ssh *ssh, Session *s) 2092 { 2093 char *name, *val; 2094 u_int name_len, val_len, i; 2095 2096 name = packet_get_cstring(&name_len); 2097 val = packet_get_cstring(&val_len); 2098 packet_check_eom(); 2099 2100 /* Don't set too many environment variables */ 2101 if (s->num_env > 128) { 2102 debug2("Ignoring env request %s: too many env vars", name); 2103 goto fail; 2104 } 2105 2106 for (i = 0; i < options.num_accept_env; i++) { 2107 if (match_pattern(name, options.accept_env[i])) { 2108 debug2("Setting env %d: %s=%s", s->num_env, name, val); 2109 s->env = xrecallocarray(s->env, s->num_env, 2110 s->num_env + 1, sizeof(*s->env)); 2111 s->env[s->num_env].name = name; 2112 s->env[s->num_env].val = val; 2113 s->num_env++; 2114 return (1); 2115 } 2116 } 2117 debug2("Ignoring env request %s: disallowed name", name); 2118 2119 fail: 2120 free(name); 2121 free(val); 2122 return (0); 2123 } 2124 2125 /* 2126 * Conversion of signals from ssh channel request names. 2127 * Subset of signals from RFC 4254 section 6.10C, with SIGINFO as 2128 * local extension. 2129 */ 2130 static int 2131 name2sig(char *name) 2132 { 2133 #define SSH_SIG(x) if (strcmp(name, #x) == 0) return SIG ## x 2134 SSH_SIG(HUP); 2135 SSH_SIG(INT); 2136 SSH_SIG(KILL); 2137 SSH_SIG(QUIT); 2138 SSH_SIG(TERM); 2139 SSH_SIG(USR1); 2140 SSH_SIG(USR2); 2141 #undef SSH_SIG 2142 #ifdef SIGINFO 2143 if (strcmp(name, "INFO@openssh.com") == 0) 2144 return SIGINFO; 2145 #endif 2146 return -1; 2147 } 2148 2149 static int 2150 session_signal_req(struct ssh *ssh, Session *s) 2151 { 2152 char *signame = NULL; 2153 int r, sig, success = 0; 2154 2155 if ((r = sshpkt_get_cstring(ssh, &signame, NULL)) != 0 || 2156 (r = sshpkt_get_end(ssh)) != 0) { 2157 error("%s: parse packet: %s", __func__, ssh_err(r)); 2158 goto out; 2159 } 2160 if ((sig = name2sig(signame)) == -1) { 2161 error("%s: unsupported signal \"%s\"", __func__, signame); 2162 goto out; 2163 } 2164 if (s->pid <= 0) { 2165 error("%s: no pid for session %d", __func__, s->self); 2166 goto out; 2167 } 2168 if (s->forced || s->is_subsystem) { 2169 error("%s: refusing to send signal %s to %s session", __func__, 2170 signame, s->forced ? "forced-command" : "subsystem"); 2171 goto out; 2172 } 2173 if (!use_privsep || mm_is_monitor()) { 2174 error("%s: session signalling requires privilege separation", 2175 __func__); 2176 goto out; 2177 } 2178 2179 debug("%s: signal %s, killpg(%ld, %d)", __func__, signame, 2180 (long)s->pid, sig); 2181 temporarily_use_uid(s->pw); 2182 r = killpg(s->pid, sig); 2183 restore_uid(); 2184 if (r != 0) { 2185 error("%s: killpg(%ld, %d): %s", __func__, (long)s->pid, 2186 sig, strerror(errno)); 2187 goto out; 2188 } 2189 2190 /* success */ 2191 success = 1; 2192 out: 2193 free(signame); 2194 return success; 2195 } 2196 2197 static int 2198 session_auth_agent_req(struct ssh *ssh, Session *s) 2199 { 2200 static int called = 0; 2201 2202 packet_check_eom(); 2203 if (!auth_opts->permit_agent_forwarding_flag || 2204 !options.allow_agent_forwarding) { 2205 debug("%s: agent forwarding disabled", __func__); 2206 return 0; 2207 } 2208 if (called) { 2209 return 0; 2210 } else { 2211 called = 1; 2212 return auth_input_request_forwarding(ssh, s->pw); 2213 } 2214 } 2215 2216 int 2217 session_input_channel_req(struct ssh *ssh, Channel *c, const char *rtype) 2218 { 2219 int success = 0; 2220 Session *s; 2221 2222 if ((s = session_by_channel(c->self)) == NULL) { 2223 logit("%s: no session %d req %.100s", __func__, c->self, rtype); 2224 return 0; 2225 } 2226 debug("%s: session %d req %s", __func__, s->self, rtype); 2227 2228 /* 2229 * a session is in LARVAL state until a shell, a command 2230 * or a subsystem is executed 2231 */ 2232 if (c->type == SSH_CHANNEL_LARVAL) { 2233 if (strcmp(rtype, "shell") == 0) { 2234 success = session_shell_req(ssh, s); 2235 } else if (strcmp(rtype, "exec") == 0) { 2236 success = session_exec_req(ssh, s); 2237 } else if (strcmp(rtype, "pty-req") == 0) { 2238 success = session_pty_req(ssh, s); 2239 } else if (strcmp(rtype, "x11-req") == 0) { 2240 success = session_x11_req(ssh, s); 2241 } else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) { 2242 success = session_auth_agent_req(ssh, s); 2243 } else if (strcmp(rtype, "subsystem") == 0) { 2244 success = session_subsystem_req(ssh, s); 2245 } else if (strcmp(rtype, "env") == 0) { 2246 success = session_env_req(ssh, s); 2247 } 2248 } 2249 if (strcmp(rtype, "window-change") == 0) { 2250 success = session_window_change_req(ssh, s); 2251 } else if (strcmp(rtype, "break") == 0) { 2252 success = session_break_req(ssh, s); 2253 } else if (strcmp(rtype, "signal") == 0) { 2254 success = session_signal_req(ssh, s); 2255 } 2256 2257 return success; 2258 } 2259 2260 void 2261 session_set_fds(struct ssh *ssh, Session *s, 2262 int fdin, int fdout, int fderr, int ignore_fderr, int is_tty) 2263 { 2264 /* 2265 * now that have a child and a pipe to the child, 2266 * we can activate our channel and register the fd's 2267 */ 2268 if (s->chanid == -1) 2269 fatal("no channel for session %d", s->self); 2270 channel_set_fds(ssh, s->chanid, 2271 fdout, fdin, fderr, 2272 ignore_fderr ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ, 2273 1, is_tty, CHAN_SES_WINDOW_DEFAULT); 2274 } 2275 2276 /* 2277 * Function to perform pty cleanup. Also called if we get aborted abnormally 2278 * (e.g., due to a dropped connection). 2279 */ 2280 void 2281 session_pty_cleanup2(Session *s) 2282 { 2283 if (s == NULL) { 2284 error("%s: no session", __func__); 2285 return; 2286 } 2287 if (s->ttyfd == -1) 2288 return; 2289 2290 debug("%s: session %d release %s", __func__, s->self, s->tty); 2291 2292 /* Record that the user has logged out. */ 2293 if (s->pid != 0) 2294 record_logout(s->pid, s->tty, s->pw->pw_name); 2295 2296 /* Release the pseudo-tty. */ 2297 if (getuid() == 0) 2298 pty_release(s->tty); 2299 2300 /* 2301 * Close the server side of the socket pairs. We must do this after 2302 * the pty cleanup, so that another process doesn't get this pty 2303 * while we're still cleaning up. 2304 */ 2305 if (s->ptymaster != -1 && close(s->ptymaster) < 0) 2306 error("close(s->ptymaster/%d): %s", 2307 s->ptymaster, strerror(errno)); 2308 2309 /* unlink pty from session */ 2310 s->ttyfd = -1; 2311 } 2312 2313 void 2314 session_pty_cleanup(Session *s) 2315 { 2316 PRIVSEP(session_pty_cleanup2(s)); 2317 } 2318 2319 static char * 2320 sig2name(int sig) 2321 { 2322 #define SSH_SIG(x) if (sig == SIG ## x) return #x 2323 SSH_SIG(ABRT); 2324 SSH_SIG(ALRM); 2325 SSH_SIG(FPE); 2326 SSH_SIG(HUP); 2327 SSH_SIG(ILL); 2328 SSH_SIG(INT); 2329 SSH_SIG(KILL); 2330 SSH_SIG(PIPE); 2331 SSH_SIG(QUIT); 2332 SSH_SIG(SEGV); 2333 SSH_SIG(TERM); 2334 SSH_SIG(USR1); 2335 SSH_SIG(USR2); 2336 #undef SSH_SIG 2337 return "SIG@openssh.com"; 2338 } 2339 2340 static void 2341 session_close_x11(struct ssh *ssh, int id) 2342 { 2343 Channel *c; 2344 2345 if ((c = channel_by_id(ssh, id)) == NULL) { 2346 debug("%s: x11 channel %d missing", __func__, id); 2347 } else { 2348 /* Detach X11 listener */ 2349 debug("%s: detach x11 channel %d", __func__, id); 2350 channel_cancel_cleanup(ssh, id); 2351 if (c->ostate != CHAN_OUTPUT_CLOSED) 2352 chan_mark_dead(ssh, c); 2353 } 2354 } 2355 2356 static void 2357 session_close_single_x11(struct ssh *ssh, int id, void *arg) 2358 { 2359 Session *s; 2360 u_int i; 2361 2362 debug3("%s: channel %d", __func__, id); 2363 channel_cancel_cleanup(ssh, id); 2364 if ((s = session_by_x11_channel(id)) == NULL) 2365 fatal("%s: no x11 channel %d", __func__, id); 2366 for (i = 0; s->x11_chanids[i] != -1; i++) { 2367 debug("%s: session %d: closing channel %d", 2368 __func__, s->self, s->x11_chanids[i]); 2369 /* 2370 * The channel "id" is already closing, but make sure we 2371 * close all of its siblings. 2372 */ 2373 if (s->x11_chanids[i] != id) 2374 session_close_x11(ssh, s->x11_chanids[i]); 2375 } 2376 free(s->x11_chanids); 2377 s->x11_chanids = NULL; 2378 free(s->display); 2379 s->display = NULL; 2380 free(s->auth_proto); 2381 s->auth_proto = NULL; 2382 free(s->auth_data); 2383 s->auth_data = NULL; 2384 free(s->auth_display); 2385 s->auth_display = NULL; 2386 } 2387 2388 static void 2389 session_exit_message(struct ssh *ssh, Session *s, int status) 2390 { 2391 Channel *c; 2392 2393 if ((c = channel_lookup(ssh, s->chanid)) == NULL) 2394 fatal("%s: session %d: no channel %d", 2395 __func__, s->self, s->chanid); 2396 debug("%s: session %d channel %d pid %ld", 2397 __func__, s->self, s->chanid, (long)s->pid); 2398 2399 if (WIFEXITED(status)) { 2400 channel_request_start(ssh, s->chanid, "exit-status", 0); 2401 packet_put_int(WEXITSTATUS(status)); 2402 packet_send(); 2403 } else if (WIFSIGNALED(status)) { 2404 channel_request_start(ssh, s->chanid, "exit-signal", 0); 2405 packet_put_cstring(sig2name(WTERMSIG(status))); 2406 #ifdef WCOREDUMP 2407 packet_put_char(WCOREDUMP(status)? 1 : 0); 2408 #else /* WCOREDUMP */ 2409 packet_put_char(0); 2410 #endif /* WCOREDUMP */ 2411 packet_put_cstring(""); 2412 packet_put_cstring(""); 2413 packet_send(); 2414 } else { 2415 /* Some weird exit cause. Just exit. */ 2416 packet_disconnect("wait returned status %04x.", status); 2417 } 2418 2419 /* disconnect channel */ 2420 debug("%s: release channel %d", __func__, s->chanid); 2421 2422 /* 2423 * Adjust cleanup callback attachment to send close messages when 2424 * the channel gets EOF. The session will be then be closed 2425 * by session_close_by_channel when the childs close their fds. 2426 */ 2427 channel_register_cleanup(ssh, c->self, session_close_by_channel, 1); 2428 2429 /* 2430 * emulate a write failure with 'chan_write_failed', nobody will be 2431 * interested in data we write. 2432 * Note that we must not call 'chan_read_failed', since there could 2433 * be some more data waiting in the pipe. 2434 */ 2435 if (c->ostate != CHAN_OUTPUT_CLOSED) 2436 chan_write_failed(ssh, c); 2437 } 2438 2439 void 2440 session_close(struct ssh *ssh, Session *s) 2441 { 2442 u_int i; 2443 2444 verbose("Close session: user %s from %.200s port %d id %d", 2445 s->pw->pw_name, 2446 ssh_remote_ipaddr(ssh), 2447 ssh_remote_port(ssh), 2448 s->self); 2449 2450 if (s->ttyfd != -1) 2451 session_pty_cleanup(s); 2452 free(s->term); 2453 free(s->display); 2454 free(s->x11_chanids); 2455 free(s->auth_display); 2456 free(s->auth_data); 2457 free(s->auth_proto); 2458 free(s->subsys); 2459 if (s->env != NULL) { 2460 for (i = 0; i < s->num_env; i++) { 2461 free(s->env[i].name); 2462 free(s->env[i].val); 2463 } 2464 free(s->env); 2465 } 2466 session_proctitle(s); 2467 session_unused(s->self); 2468 } 2469 2470 void 2471 session_close_by_pid(struct ssh *ssh, pid_t pid, int status) 2472 { 2473 Session *s = session_by_pid(pid); 2474 if (s == NULL) { 2475 debug("%s: no session for pid %ld", __func__, (long)pid); 2476 return; 2477 } 2478 if (s->chanid != -1) 2479 session_exit_message(ssh, s, status); 2480 if (s->ttyfd != -1) 2481 session_pty_cleanup(s); 2482 s->pid = 0; 2483 } 2484 2485 /* 2486 * this is called when a channel dies before 2487 * the session 'child' itself dies 2488 */ 2489 void 2490 session_close_by_channel(struct ssh *ssh, int id, void *arg) 2491 { 2492 Session *s = session_by_channel(id); 2493 u_int i; 2494 2495 if (s == NULL) { 2496 debug("%s: no session for id %d", __func__, id); 2497 return; 2498 } 2499 debug("%s: channel %d child %ld", __func__, id, (long)s->pid); 2500 if (s->pid != 0) { 2501 debug("%s: channel %d: has child, ttyfd %d", 2502 __func__, id, s->ttyfd); 2503 /* 2504 * delay detach of session, but release pty, since 2505 * the fd's to the child are already closed 2506 */ 2507 if (s->ttyfd != -1) 2508 session_pty_cleanup(s); 2509 return; 2510 } 2511 /* detach by removing callback */ 2512 channel_cancel_cleanup(ssh, s->chanid); 2513 2514 /* Close any X11 listeners associated with this session */ 2515 if (s->x11_chanids != NULL) { 2516 for (i = 0; s->x11_chanids[i] != -1; i++) { 2517 session_close_x11(ssh, s->x11_chanids[i]); 2518 s->x11_chanids[i] = -1; 2519 } 2520 } 2521 2522 s->chanid = -1; 2523 session_close(ssh, s); 2524 } 2525 2526 void 2527 session_destroy_all(struct ssh *ssh, void (*closefunc)(Session *)) 2528 { 2529 int i; 2530 for (i = 0; i < sessions_nalloc; i++) { 2531 Session *s = &sessions[i]; 2532 if (s->used) { 2533 if (closefunc != NULL) 2534 closefunc(s); 2535 else 2536 session_close(ssh, s); 2537 } 2538 } 2539 } 2540 2541 static char * 2542 session_tty_list(void) 2543 { 2544 static char buf[1024]; 2545 int i; 2546 char *cp; 2547 2548 buf[0] = '\0'; 2549 for (i = 0; i < sessions_nalloc; i++) { 2550 Session *s = &sessions[i]; 2551 if (s->used && s->ttyfd != -1) { 2552 2553 if (strncmp(s->tty, "/dev/", 5) != 0) { 2554 cp = strrchr(s->tty, '/'); 2555 cp = (cp == NULL) ? s->tty : cp + 1; 2556 } else 2557 cp = s->tty + 5; 2558 2559 if (buf[0] != '\0') 2560 strlcat(buf, ",", sizeof buf); 2561 strlcat(buf, cp, sizeof buf); 2562 } 2563 } 2564 if (buf[0] == '\0') 2565 strlcpy(buf, "notty", sizeof buf); 2566 return buf; 2567 } 2568 2569 void 2570 session_proctitle(Session *s) 2571 { 2572 if (s->pw == NULL) 2573 error("no user for session %d", s->self); 2574 else 2575 setproctitle("%s@%s", s->pw->pw_name, session_tty_list()); 2576 } 2577 2578 int 2579 session_setup_x11fwd(struct ssh *ssh, Session *s) 2580 { 2581 struct stat st; 2582 char display[512], auth_display[512]; 2583 char hostname[NI_MAXHOST]; 2584 u_int i; 2585 2586 if (!auth_opts->permit_x11_forwarding_flag) { 2587 packet_send_debug("X11 forwarding disabled by key options."); 2588 return 0; 2589 } 2590 if (!options.x11_forwarding) { 2591 debug("X11 forwarding disabled in server configuration file."); 2592 return 0; 2593 } 2594 if (options.xauth_location == NULL || 2595 (stat(options.xauth_location, &st) == -1)) { 2596 packet_send_debug("No xauth program; cannot forward X11."); 2597 return 0; 2598 } 2599 if (s->display != NULL) { 2600 debug("X11 display already set."); 2601 return 0; 2602 } 2603 if (x11_create_display_inet(ssh, options.x11_display_offset, 2604 options.x11_use_localhost, s->single_connection, 2605 &s->display_number, &s->x11_chanids) == -1) { 2606 debug("x11_create_display_inet failed."); 2607 return 0; 2608 } 2609 for (i = 0; s->x11_chanids[i] != -1; i++) { 2610 channel_register_cleanup(ssh, s->x11_chanids[i], 2611 session_close_single_x11, 0); 2612 } 2613 2614 /* Set up a suitable value for the DISPLAY variable. */ 2615 if (gethostname(hostname, sizeof(hostname)) < 0) 2616 fatal("gethostname: %.100s", strerror(errno)); 2617 /* 2618 * auth_display must be used as the displayname when the 2619 * authorization entry is added with xauth(1). This will be 2620 * different than the DISPLAY string for localhost displays. 2621 */ 2622 if (options.x11_use_localhost) { 2623 snprintf(display, sizeof display, "localhost:%u.%u", 2624 s->display_number, s->screen); 2625 snprintf(auth_display, sizeof auth_display, "unix:%u.%u", 2626 s->display_number, s->screen); 2627 s->display = xstrdup(display); 2628 s->auth_display = xstrdup(auth_display); 2629 } else { 2630 #ifdef IPADDR_IN_DISPLAY 2631 struct hostent *he; 2632 struct in_addr my_addr; 2633 2634 he = gethostbyname(hostname); 2635 if (he == NULL) { 2636 error("Can't get IP address for X11 DISPLAY."); 2637 packet_send_debug("Can't get IP address for X11 DISPLAY."); 2638 return 0; 2639 } 2640 memcpy(&my_addr, he->h_addr_list[0], sizeof(struct in_addr)); 2641 snprintf(display, sizeof display, "%.50s:%u.%u", inet_ntoa(my_addr), 2642 s->display_number, s->screen); 2643 #else 2644 snprintf(display, sizeof display, "%.400s:%u.%u", hostname, 2645 s->display_number, s->screen); 2646 #endif 2647 s->display = xstrdup(display); 2648 s->auth_display = xstrdup(display); 2649 } 2650 2651 return 1; 2652 } 2653 2654 static void 2655 do_authenticated2(struct ssh *ssh, Authctxt *authctxt) 2656 { 2657 server_loop2(ssh, authctxt); 2658 } 2659 2660 void 2661 do_cleanup(struct ssh *ssh, Authctxt *authctxt) 2662 { 2663 static int called = 0; 2664 2665 debug("do_cleanup"); 2666 2667 /* no cleanup if we're in the child for login shell */ 2668 if (is_child) 2669 return; 2670 2671 /* avoid double cleanup */ 2672 if (called) 2673 return; 2674 called = 1; 2675 2676 if (authctxt == NULL) 2677 return; 2678 2679 #ifdef USE_PAM 2680 if (options.use_pam) { 2681 sshpam_cleanup(); 2682 sshpam_thread_cleanup(); 2683 } 2684 #endif 2685 2686 if (!authctxt->authenticated) 2687 return; 2688 2689 #ifdef KRB5 2690 if (options.kerberos_ticket_cleanup && 2691 authctxt->krb5_ctx) 2692 krb5_cleanup_proc(authctxt); 2693 #endif 2694 2695 #ifdef GSSAPI 2696 if (options.gss_cleanup_creds) 2697 ssh_gssapi_cleanup_creds(); 2698 #endif 2699 2700 /* remove agent socket */ 2701 auth_sock_cleanup_proc(authctxt->pw); 2702 2703 /* remove userauth info */ 2704 if (auth_info_file != NULL) { 2705 temporarily_use_uid(authctxt->pw); 2706 unlink(auth_info_file); 2707 restore_uid(); 2708 free(auth_info_file); 2709 auth_info_file = NULL; 2710 } 2711 2712 /* 2713 * Cleanup ptys/utmp only if privsep is disabled, 2714 * or if running in monitor. 2715 */ 2716 if (!use_privsep || mm_is_monitor()) 2717 session_destroy_all(ssh, session_pty_cleanup2); 2718 } 2719 2720 /* Return a name for the remote host that fits inside utmp_size */ 2721 2722 const char * 2723 session_get_remote_name_or_ip(struct ssh *ssh, u_int utmp_size, int use_dns) 2724 { 2725 const char *remote = ""; 2726 2727 if (utmp_size > 0) 2728 remote = auth_get_canonical_hostname(ssh, use_dns); 2729 if (utmp_size == 0 || strlen(remote) > utmp_size) 2730 remote = ssh_remote_ipaddr(ssh); 2731 return remote; 2732 } 2733 2734