1 /* $OpenBSD: session.c,v 1.319 2020/03/13 03:17:07 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 38 #include <sys/types.h> 39 #include <sys/param.h> 40 #ifdef HAVE_SYS_STAT_H 41 # include <sys/stat.h> 42 #endif 43 #include <sys/socket.h> 44 #include <sys/un.h> 45 #include <sys/wait.h> 46 47 #include <arpa/inet.h> 48 49 #include <ctype.h> 50 #include <errno.h> 51 #include <fcntl.h> 52 #include <grp.h> 53 #include <netdb.h> 54 #ifdef HAVE_PATHS_H 55 #include <paths.h> 56 #endif 57 #include <pwd.h> 58 #include <signal.h> 59 #include <stdio.h> 60 #include <stdlib.h> 61 #include <string.h> 62 #include <stdarg.h> 63 #include <unistd.h> 64 #include <limits.h> 65 66 #include "openbsd-compat/sys-queue.h" 67 #include "xmalloc.h" 68 #include "ssh.h" 69 #include "ssh2.h" 70 #include "sshpty.h" 71 #include "packet.h" 72 #include "sshbuf.h" 73 #include "ssherr.h" 74 #include "match.h" 75 #include "uidswap.h" 76 #include "compat.h" 77 #include "channels.h" 78 #include "sshkey.h" 79 #include "cipher.h" 80 #ifdef GSSAPI 81 #include "ssh-gss.h" 82 #endif 83 #include "hostfile.h" 84 #include "auth.h" 85 #include "auth-options.h" 86 #include "authfd.h" 87 #include "pathnames.h" 88 #include "log.h" 89 #include "misc.h" 90 #include "servconf.h" 91 #include "sshlogin.h" 92 #include "serverloop.h" 93 #include "canohost.h" 94 #include "session.h" 95 #include "kex.h" 96 #include "monitor_wrap.h" 97 #include "sftp.h" 98 #include "atomicio.h" 99 100 #if defined(KRB5) && defined(USE_AFS) 101 #include <kafs.h> 102 #endif 103 104 #ifdef WITH_SELINUX 105 #include <selinux/selinux.h> 106 #endif 107 108 #define IS_INTERNAL_SFTP(c) \ 109 (!strncmp(c, INTERNAL_SFTP_NAME, sizeof(INTERNAL_SFTP_NAME) - 1) && \ 110 (c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\0' || \ 111 c[sizeof(INTERNAL_SFTP_NAME) - 1] == ' ' || \ 112 c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\t')) 113 114 /* func */ 115 116 Session *session_new(void); 117 void session_set_fds(struct ssh *, Session *, int, int, int, int, int); 118 void session_pty_cleanup(Session *); 119 void session_proctitle(Session *); 120 int session_setup_x11fwd(struct ssh *, Session *); 121 int do_exec_pty(struct ssh *, Session *, const char *); 122 int do_exec_no_pty(struct ssh *, Session *, const char *); 123 int do_exec(struct ssh *, Session *, const char *); 124 void do_login(struct ssh *, Session *, const char *); 125 void do_child(struct ssh *, Session *, const char *); 126 void do_motd(void); 127 int check_quietlogin(Session *, const char *); 128 129 static void do_authenticated2(struct ssh *, Authctxt *); 130 131 static int session_pty_req(struct ssh *, Session *); 132 133 /* import */ 134 extern ServerOptions options; 135 extern char *__progname; 136 extern int debug_flag; 137 extern u_int utmp_len; 138 extern int startup_pipe; 139 extern void destroy_sensitive_data(void); 140 extern struct sshbuf *loginmsg; 141 extern struct sshauthopt *auth_opts; 142 extern char *tun_fwd_ifnames; /* serverloop.c */ 143 144 /* original command from peer. */ 145 const char *original_command = NULL; 146 147 /* data */ 148 static int sessions_first_unused = -1; 149 static int sessions_nalloc = 0; 150 static Session *sessions = NULL; 151 152 #define SUBSYSTEM_NONE 0 153 #define SUBSYSTEM_EXT 1 154 #define SUBSYSTEM_INT_SFTP 2 155 #define SUBSYSTEM_INT_SFTP_ERROR 3 156 157 #ifdef HAVE_LOGIN_CAP 158 login_cap_t *lc; 159 #endif 160 161 static int is_child = 0; 162 static int in_chroot = 0; 163 164 /* File containing userauth info, if ExposeAuthInfo set */ 165 static char *auth_info_file = NULL; 166 167 /* Name and directory of socket for authentication agent forwarding. */ 168 static char *auth_sock_name = NULL; 169 static char *auth_sock_dir = NULL; 170 171 /* removes the agent forwarding socket */ 172 173 static void 174 auth_sock_cleanup_proc(struct passwd *pw) 175 { 176 if (auth_sock_name != NULL) { 177 temporarily_use_uid(pw); 178 unlink(auth_sock_name); 179 rmdir(auth_sock_dir); 180 auth_sock_name = NULL; 181 restore_uid(); 182 } 183 } 184 185 static int 186 auth_input_request_forwarding(struct ssh *ssh, struct passwd * pw) 187 { 188 Channel *nc; 189 int sock = -1; 190 191 if (auth_sock_name != NULL) { 192 error("authentication forwarding requested twice."); 193 return 0; 194 } 195 196 /* Temporarily drop privileged uid for mkdir/bind. */ 197 temporarily_use_uid(pw); 198 199 /* Allocate a buffer for the socket name, and format the name. */ 200 auth_sock_dir = xstrdup("/tmp/ssh-XXXXXXXXXX"); 201 202 /* Create private directory for socket */ 203 if (mkdtemp(auth_sock_dir) == NULL) { 204 ssh_packet_send_debug(ssh, "Agent forwarding disabled: " 205 "mkdtemp() failed: %.100s", strerror(errno)); 206 restore_uid(); 207 free(auth_sock_dir); 208 auth_sock_dir = NULL; 209 goto authsock_err; 210 } 211 212 xasprintf(&auth_sock_name, "%s/agent.%ld", 213 auth_sock_dir, (long) getpid()); 214 215 /* Start a Unix listener on auth_sock_name. */ 216 sock = unix_listener(auth_sock_name, SSH_LISTEN_BACKLOG, 0); 217 218 /* Restore the privileged uid. */ 219 restore_uid(); 220 221 /* Check for socket/bind/listen failure. */ 222 if (sock < 0) 223 goto authsock_err; 224 225 /* Allocate a channel for the authentication agent socket. */ 226 nc = channel_new(ssh, "auth socket", 227 SSH_CHANNEL_AUTH_SOCKET, sock, sock, -1, 228 CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 229 0, "auth socket", 1); 230 nc->path = xstrdup(auth_sock_name); 231 return 1; 232 233 authsock_err: 234 free(auth_sock_name); 235 if (auth_sock_dir != NULL) { 236 temporarily_use_uid(pw); 237 rmdir(auth_sock_dir); 238 restore_uid(); 239 free(auth_sock_dir); 240 } 241 if (sock != -1) 242 close(sock); 243 auth_sock_name = NULL; 244 auth_sock_dir = NULL; 245 return 0; 246 } 247 248 static void 249 display_loginmsg(void) 250 { 251 int r; 252 253 if (sshbuf_len(loginmsg) == 0) 254 return; 255 if ((r = sshbuf_put_u8(loginmsg, 0)) != 0) 256 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 257 printf("%s", (char *)sshbuf_ptr(loginmsg)); 258 sshbuf_reset(loginmsg); 259 } 260 261 static void 262 prepare_auth_info_file(struct passwd *pw, struct sshbuf *info) 263 { 264 int fd = -1, success = 0; 265 266 if (!options.expose_userauth_info || info == NULL) 267 return; 268 269 temporarily_use_uid(pw); 270 auth_info_file = xstrdup("/tmp/sshauth.XXXXXXXXXXXXXXX"); 271 if ((fd = mkstemp(auth_info_file)) == -1) { 272 error("%s: mkstemp: %s", __func__, strerror(errno)); 273 goto out; 274 } 275 if (atomicio(vwrite, fd, sshbuf_mutable_ptr(info), 276 sshbuf_len(info)) != sshbuf_len(info)) { 277 error("%s: write: %s", __func__, strerror(errno)); 278 goto out; 279 } 280 if (close(fd) != 0) { 281 error("%s: close: %s", __func__, strerror(errno)); 282 goto out; 283 } 284 success = 1; 285 out: 286 if (!success) { 287 if (fd != -1) 288 close(fd); 289 free(auth_info_file); 290 auth_info_file = NULL; 291 } 292 restore_uid(); 293 } 294 295 static void 296 set_fwdpermit_from_authopts(struct ssh *ssh, const struct sshauthopt *opts) 297 { 298 char *tmp, *cp, *host; 299 int port; 300 size_t i; 301 302 if ((options.allow_tcp_forwarding & FORWARD_LOCAL) != 0) { 303 channel_clear_permission(ssh, FORWARD_USER, FORWARD_LOCAL); 304 for (i = 0; i < auth_opts->npermitopen; i++) { 305 tmp = cp = xstrdup(auth_opts->permitopen[i]); 306 /* This shouldn't fail as it has already been checked */ 307 if ((host = hpdelim(&cp)) == NULL) 308 fatal("%s: internal error: hpdelim", __func__); 309 host = cleanhostname(host); 310 if (cp == NULL || (port = permitopen_port(cp)) < 0) 311 fatal("%s: internal error: permitopen port", 312 __func__); 313 channel_add_permission(ssh, 314 FORWARD_USER, FORWARD_LOCAL, host, port); 315 free(tmp); 316 } 317 } 318 if ((options.allow_tcp_forwarding & FORWARD_REMOTE) != 0) { 319 channel_clear_permission(ssh, FORWARD_USER, FORWARD_REMOTE); 320 for (i = 0; i < auth_opts->npermitlisten; i++) { 321 tmp = cp = xstrdup(auth_opts->permitlisten[i]); 322 /* This shouldn't fail as it has already been checked */ 323 if ((host = hpdelim(&cp)) == NULL) 324 fatal("%s: internal error: hpdelim", __func__); 325 host = cleanhostname(host); 326 if (cp == NULL || (port = permitopen_port(cp)) < 0) 327 fatal("%s: internal error: permitlisten port", 328 __func__); 329 channel_add_permission(ssh, 330 FORWARD_USER, FORWARD_REMOTE, host, port); 331 free(tmp); 332 } 333 } 334 } 335 336 void 337 do_authenticated(struct ssh *ssh, Authctxt *authctxt) 338 { 339 setproctitle("%s", authctxt->pw->pw_name); 340 341 auth_log_authopts("active", auth_opts, 0); 342 343 /* setup the channel layer */ 344 /* XXX - streamlocal? */ 345 set_fwdpermit_from_authopts(ssh, auth_opts); 346 347 if (!auth_opts->permit_port_forwarding_flag || 348 options.disable_forwarding) { 349 channel_disable_admin(ssh, FORWARD_LOCAL); 350 channel_disable_admin(ssh, FORWARD_REMOTE); 351 } else { 352 if ((options.allow_tcp_forwarding & FORWARD_LOCAL) == 0) 353 channel_disable_admin(ssh, FORWARD_LOCAL); 354 else 355 channel_permit_all(ssh, FORWARD_LOCAL); 356 if ((options.allow_tcp_forwarding & FORWARD_REMOTE) == 0) 357 channel_disable_admin(ssh, FORWARD_REMOTE); 358 else 359 channel_permit_all(ssh, FORWARD_REMOTE); 360 } 361 auth_debug_send(ssh); 362 363 prepare_auth_info_file(authctxt->pw, authctxt->session_info); 364 365 do_authenticated2(ssh, authctxt); 366 367 do_cleanup(ssh, authctxt); 368 } 369 370 /* Check untrusted xauth strings for metacharacters */ 371 static int 372 xauth_valid_string(const char *s) 373 { 374 size_t i; 375 376 for (i = 0; s[i] != '\0'; i++) { 377 if (!isalnum((u_char)s[i]) && 378 s[i] != '.' && s[i] != ':' && s[i] != '/' && 379 s[i] != '-' && s[i] != '_') 380 return 0; 381 } 382 return 1; 383 } 384 385 #define USE_PIPES 1 386 /* 387 * This is called to fork and execute a command when we have no tty. This 388 * will call do_child from the child, and server_loop from the parent after 389 * setting up file descriptors and such. 390 */ 391 int 392 do_exec_no_pty(struct ssh *ssh, Session *s, const char *command) 393 { 394 pid_t pid; 395 #ifdef USE_PIPES 396 int pin[2], pout[2], perr[2]; 397 398 if (s == NULL) 399 fatal("do_exec_no_pty: no session"); 400 401 /* Allocate pipes for communicating with the program. */ 402 if (pipe(pin) == -1) { 403 error("%s: pipe in: %.100s", __func__, strerror(errno)); 404 return -1; 405 } 406 if (pipe(pout) == -1) { 407 error("%s: pipe out: %.100s", __func__, strerror(errno)); 408 close(pin[0]); 409 close(pin[1]); 410 return -1; 411 } 412 if (pipe(perr) == -1) { 413 error("%s: pipe err: %.100s", __func__, 414 strerror(errno)); 415 close(pin[0]); 416 close(pin[1]); 417 close(pout[0]); 418 close(pout[1]); 419 return -1; 420 } 421 #else 422 int inout[2], err[2]; 423 424 if (s == NULL) 425 fatal("do_exec_no_pty: no session"); 426 427 /* Uses socket pairs to communicate with the program. */ 428 if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) == -1) { 429 error("%s: socketpair #1: %.100s", __func__, strerror(errno)); 430 return -1; 431 } 432 if (socketpair(AF_UNIX, SOCK_STREAM, 0, err) == -1) { 433 error("%s: socketpair #2: %.100s", __func__, 434 strerror(errno)); 435 close(inout[0]); 436 close(inout[1]); 437 return -1; 438 } 439 #endif 440 441 session_proctitle(s); 442 443 /* Fork the child. */ 444 switch ((pid = fork())) { 445 case -1: 446 error("%s: fork: %.100s", __func__, strerror(errno)); 447 #ifdef USE_PIPES 448 close(pin[0]); 449 close(pin[1]); 450 close(pout[0]); 451 close(pout[1]); 452 close(perr[0]); 453 close(perr[1]); 454 #else 455 close(inout[0]); 456 close(inout[1]); 457 close(err[0]); 458 close(err[1]); 459 #endif 460 return -1; 461 case 0: 462 is_child = 1; 463 464 /* 465 * Create a new session and process group since the 4.4BSD 466 * setlogin() affects the entire process group. 467 */ 468 if (setsid() == -1) 469 error("setsid failed: %.100s", strerror(errno)); 470 471 #ifdef USE_PIPES 472 /* 473 * Redirect stdin. We close the parent side of the socket 474 * pair, and make the child side the standard input. 475 */ 476 close(pin[1]); 477 if (dup2(pin[0], 0) == -1) 478 perror("dup2 stdin"); 479 close(pin[0]); 480 481 /* Redirect stdout. */ 482 close(pout[0]); 483 if (dup2(pout[1], 1) == -1) 484 perror("dup2 stdout"); 485 close(pout[1]); 486 487 /* Redirect stderr. */ 488 close(perr[0]); 489 if (dup2(perr[1], 2) == -1) 490 perror("dup2 stderr"); 491 close(perr[1]); 492 #else 493 /* 494 * Redirect stdin, stdout, and stderr. Stdin and stdout will 495 * use the same socket, as some programs (particularly rdist) 496 * seem to depend on it. 497 */ 498 close(inout[1]); 499 close(err[1]); 500 if (dup2(inout[0], 0) == -1) /* stdin */ 501 perror("dup2 stdin"); 502 if (dup2(inout[0], 1) == -1) /* stdout (same as stdin) */ 503 perror("dup2 stdout"); 504 close(inout[0]); 505 if (dup2(err[0], 2) == -1) /* stderr */ 506 perror("dup2 stderr"); 507 close(err[0]); 508 #endif 509 510 /* Do processing for the child (exec command etc). */ 511 do_child(ssh, s, command); 512 /* NOTREACHED */ 513 default: 514 break; 515 } 516 517 #ifdef HAVE_CYGWIN 518 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); 519 #endif 520 521 s->pid = pid; 522 /* Set interactive/non-interactive mode. */ 523 ssh_packet_set_interactive(ssh, s->display != NULL, 524 options.ip_qos_interactive, options.ip_qos_bulk); 525 526 /* 527 * Clear loginmsg, since it's the child's responsibility to display 528 * it to the user, otherwise multiple sessions may accumulate 529 * multiple copies of the login messages. 530 */ 531 sshbuf_reset(loginmsg); 532 533 #ifdef USE_PIPES 534 /* We are the parent. Close the child sides of the pipes. */ 535 close(pin[0]); 536 close(pout[1]); 537 close(perr[1]); 538 539 session_set_fds(ssh, s, pin[1], pout[0], perr[0], 540 s->is_subsystem, 0); 541 #else 542 /* We are the parent. Close the child sides of the socket pairs. */ 543 close(inout[0]); 544 close(err[0]); 545 546 /* 547 * Enter the interactive session. Note: server_loop must be able to 548 * handle the case that fdin and fdout are the same. 549 */ 550 session_set_fds(ssh, s, inout[1], inout[1], err[1], 551 s->is_subsystem, 0); 552 #endif 553 return 0; 554 } 555 556 /* 557 * This is called to fork and execute a command when we have a tty. This 558 * will call do_child from the child, and server_loop from the parent after 559 * setting up file descriptors, controlling tty, updating wtmp, utmp, 560 * lastlog, and other such operations. 561 */ 562 int 563 do_exec_pty(struct ssh *ssh, Session *s, const char *command) 564 { 565 int fdout, ptyfd, ttyfd, ptymaster; 566 pid_t pid; 567 568 if (s == NULL) 569 fatal("do_exec_pty: no session"); 570 ptyfd = s->ptyfd; 571 ttyfd = s->ttyfd; 572 573 /* 574 * Create another descriptor of the pty master side for use as the 575 * standard input. We could use the original descriptor, but this 576 * simplifies code in server_loop. The descriptor is bidirectional. 577 * Do this before forking (and cleanup in the child) so as to 578 * detect and gracefully fail out-of-fd conditions. 579 */ 580 if ((fdout = dup(ptyfd)) == -1) { 581 error("%s: dup #1: %s", __func__, strerror(errno)); 582 close(ttyfd); 583 close(ptyfd); 584 return -1; 585 } 586 /* we keep a reference to the pty master */ 587 if ((ptymaster = dup(ptyfd)) == -1) { 588 error("%s: dup #2: %s", __func__, strerror(errno)); 589 close(ttyfd); 590 close(ptyfd); 591 close(fdout); 592 return -1; 593 } 594 595 /* Fork the child. */ 596 switch ((pid = fork())) { 597 case -1: 598 error("%s: fork: %.100s", __func__, strerror(errno)); 599 close(fdout); 600 close(ptymaster); 601 close(ttyfd); 602 close(ptyfd); 603 return -1; 604 case 0: 605 is_child = 1; 606 607 close(fdout); 608 close(ptymaster); 609 610 /* Close the master side of the pseudo tty. */ 611 close(ptyfd); 612 613 /* Make the pseudo tty our controlling tty. */ 614 pty_make_controlling_tty(&ttyfd, s->tty); 615 616 /* Redirect stdin/stdout/stderr from the pseudo tty. */ 617 if (dup2(ttyfd, 0) == -1) 618 error("dup2 stdin: %s", strerror(errno)); 619 if (dup2(ttyfd, 1) == -1) 620 error("dup2 stdout: %s", strerror(errno)); 621 if (dup2(ttyfd, 2) == -1) 622 error("dup2 stderr: %s", strerror(errno)); 623 624 /* Close the extra descriptor for the pseudo tty. */ 625 close(ttyfd); 626 627 /* record login, etc. similar to login(1) */ 628 #ifndef HAVE_OSF_SIA 629 do_login(ssh, s, command); 630 #endif 631 /* 632 * Do common processing for the child, such as execing 633 * the command. 634 */ 635 do_child(ssh, s, command); 636 /* NOTREACHED */ 637 default: 638 break; 639 } 640 641 #ifdef HAVE_CYGWIN 642 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); 643 #endif 644 645 s->pid = pid; 646 647 /* Parent. Close the slave side of the pseudo tty. */ 648 close(ttyfd); 649 650 /* Enter interactive session. */ 651 s->ptymaster = ptymaster; 652 ssh_packet_set_interactive(ssh, 1, 653 options.ip_qos_interactive, options.ip_qos_bulk); 654 session_set_fds(ssh, s, ptyfd, fdout, -1, 1, 1); 655 return 0; 656 } 657 658 /* 659 * This is called to fork and execute a command. If another command is 660 * to be forced, execute that instead. 661 */ 662 int 663 do_exec(struct ssh *ssh, Session *s, const char *command) 664 { 665 int ret; 666 const char *forced = NULL, *tty = NULL; 667 char session_type[1024]; 668 669 if (options.adm_forced_command) { 670 original_command = command; 671 command = options.adm_forced_command; 672 forced = "(config)"; 673 } else if (auth_opts->force_command != NULL) { 674 original_command = command; 675 command = auth_opts->force_command; 676 forced = "(key-option)"; 677 } 678 s->forced = 0; 679 if (forced != NULL) { 680 s->forced = 1; 681 if (IS_INTERNAL_SFTP(command)) { 682 s->is_subsystem = s->is_subsystem ? 683 SUBSYSTEM_INT_SFTP : SUBSYSTEM_INT_SFTP_ERROR; 684 } else if (s->is_subsystem) 685 s->is_subsystem = SUBSYSTEM_EXT; 686 snprintf(session_type, sizeof(session_type), 687 "forced-command %s '%.900s'", forced, command); 688 } else if (s->is_subsystem) { 689 snprintf(session_type, sizeof(session_type), 690 "subsystem '%.900s'", s->subsys); 691 } else if (command == NULL) { 692 snprintf(session_type, sizeof(session_type), "shell"); 693 } else { 694 /* NB. we don't log unforced commands to preserve privacy */ 695 snprintf(session_type, sizeof(session_type), "command"); 696 } 697 698 if (s->ttyfd != -1) { 699 tty = s->tty; 700 if (strncmp(tty, "/dev/", 5) == 0) 701 tty += 5; 702 } 703 704 verbose("Starting session: %s%s%s for %s from %.200s port %d id %d", 705 session_type, 706 tty == NULL ? "" : " on ", 707 tty == NULL ? "" : tty, 708 s->pw->pw_name, 709 ssh_remote_ipaddr(ssh), 710 ssh_remote_port(ssh), 711 s->self); 712 713 #ifdef SSH_AUDIT_EVENTS 714 if (command != NULL) 715 PRIVSEP(audit_run_command(command)); 716 else if (s->ttyfd == -1) { 717 char *shell = s->pw->pw_shell; 718 719 if (shell[0] == '\0') /* empty shell means /bin/sh */ 720 shell =_PATH_BSHELL; 721 PRIVSEP(audit_run_command(shell)); 722 } 723 #endif 724 if (s->ttyfd != -1) 725 ret = do_exec_pty(ssh, s, command); 726 else 727 ret = do_exec_no_pty(ssh, s, command); 728 729 original_command = NULL; 730 731 /* 732 * Clear loginmsg: it's the child's responsibility to display 733 * it to the user, otherwise multiple sessions may accumulate 734 * multiple copies of the login messages. 735 */ 736 sshbuf_reset(loginmsg); 737 738 return ret; 739 } 740 741 /* administrative, login(1)-like work */ 742 void 743 do_login(struct ssh *ssh, Session *s, const char *command) 744 { 745 socklen_t fromlen; 746 struct sockaddr_storage from; 747 struct passwd * pw = s->pw; 748 pid_t pid = getpid(); 749 750 /* 751 * Get IP address of client. If the connection is not a socket, let 752 * the address be 0.0.0.0. 753 */ 754 memset(&from, 0, sizeof(from)); 755 fromlen = sizeof(from); 756 if (ssh_packet_connection_is_on_socket(ssh)) { 757 if (getpeername(ssh_packet_get_connection_in(ssh), 758 (struct sockaddr *)&from, &fromlen) == -1) { 759 debug("getpeername: %.100s", strerror(errno)); 760 cleanup_exit(255); 761 } 762 } 763 764 /* Record that there was a login on that tty from the remote host. */ 765 if (!use_privsep) 766 record_login(pid, s->tty, pw->pw_name, pw->pw_uid, 767 session_get_remote_name_or_ip(ssh, utmp_len, 768 options.use_dns), 769 (struct sockaddr *)&from, fromlen); 770 771 #ifdef USE_PAM 772 /* 773 * If password change is needed, do it now. 774 * This needs to occur before the ~/.hushlogin check. 775 */ 776 if (options.use_pam && !use_privsep && s->authctxt->force_pwchange) { 777 display_loginmsg(); 778 do_pam_chauthtok(); 779 s->authctxt->force_pwchange = 0; 780 /* XXX - signal [net] parent to enable forwardings */ 781 } 782 #endif 783 784 if (check_quietlogin(s, command)) 785 return; 786 787 display_loginmsg(); 788 789 do_motd(); 790 } 791 792 /* 793 * Display the message of the day. 794 */ 795 void 796 do_motd(void) 797 { 798 FILE *f; 799 char buf[256]; 800 801 if (options.print_motd) { 802 #ifdef HAVE_LOGIN_CAP 803 f = fopen(login_getcapstr(lc, "welcome", "/etc/motd", 804 "/etc/motd"), "r"); 805 #else 806 f = fopen("/etc/motd", "r"); 807 #endif 808 if (f) { 809 while (fgets(buf, sizeof(buf), f)) 810 fputs(buf, stdout); 811 fclose(f); 812 } 813 } 814 } 815 816 817 /* 818 * Check for quiet login, either .hushlogin or command given. 819 */ 820 int 821 check_quietlogin(Session *s, const char *command) 822 { 823 char buf[256]; 824 struct passwd *pw = s->pw; 825 struct stat st; 826 827 /* Return 1 if .hushlogin exists or a command given. */ 828 if (command != NULL) 829 return 1; 830 snprintf(buf, sizeof(buf), "%.200s/.hushlogin", pw->pw_dir); 831 #ifdef HAVE_LOGIN_CAP 832 if (login_getcapbool(lc, "hushlogin", 0) || stat(buf, &st) >= 0) 833 return 1; 834 #else 835 if (stat(buf, &st) >= 0) 836 return 1; 837 #endif 838 return 0; 839 } 840 841 /* 842 * Reads environment variables from the given file and adds/overrides them 843 * into the environment. If the file does not exist, this does nothing. 844 * Otherwise, it must consist of empty lines, comments (line starts with '#') 845 * and assignments of the form name=value. No other forms are allowed. 846 * If whitelist is not NULL, then it is interpreted as a pattern list and 847 * only variable names that match it will be accepted. 848 */ 849 static void 850 read_environment_file(char ***env, u_int *envsize, 851 const char *filename, const char *whitelist) 852 { 853 FILE *f; 854 char *line = NULL, *cp, *value; 855 size_t linesize = 0; 856 u_int lineno = 0; 857 858 f = fopen(filename, "r"); 859 if (!f) 860 return; 861 862 while (getline(&line, &linesize, f) != -1) { 863 if (++lineno > 1000) 864 fatal("Too many lines in environment file %s", filename); 865 for (cp = line; *cp == ' ' || *cp == '\t'; cp++) 866 ; 867 if (!*cp || *cp == '#' || *cp == '\n') 868 continue; 869 870 cp[strcspn(cp, "\n")] = '\0'; 871 872 value = strchr(cp, '='); 873 if (value == NULL) { 874 fprintf(stderr, "Bad line %u in %.100s\n", lineno, 875 filename); 876 continue; 877 } 878 /* 879 * Replace the equals sign by nul, and advance value to 880 * the value string. 881 */ 882 *value = '\0'; 883 value++; 884 if (whitelist != NULL && 885 match_pattern_list(cp, whitelist, 0) != 1) 886 continue; 887 child_set_env(env, envsize, cp, value); 888 } 889 free(line); 890 fclose(f); 891 } 892 893 #ifdef HAVE_ETC_DEFAULT_LOGIN 894 /* 895 * Return named variable from specified environment, or NULL if not present. 896 */ 897 static char * 898 child_get_env(char **env, const char *name) 899 { 900 int i; 901 size_t len; 902 903 len = strlen(name); 904 for (i=0; env[i] != NULL; i++) 905 if (strncmp(name, env[i], len) == 0 && env[i][len] == '=') 906 return(env[i] + len + 1); 907 return NULL; 908 } 909 910 /* 911 * Read /etc/default/login. 912 * We pick up the PATH (or SUPATH for root) and UMASK. 913 */ 914 static void 915 read_etc_default_login(char ***env, u_int *envsize, uid_t uid) 916 { 917 char **tmpenv = NULL, *var; 918 u_int i, tmpenvsize = 0; 919 u_long mask; 920 921 /* 922 * We don't want to copy the whole file to the child's environment, 923 * so we use a temporary environment and copy the variables we're 924 * interested in. 925 */ 926 read_environment_file(&tmpenv, &tmpenvsize, "/etc/default/login", 927 options.permit_user_env_whitelist); 928 929 if (tmpenv == NULL) 930 return; 931 932 if (uid == 0) 933 var = child_get_env(tmpenv, "SUPATH"); 934 else 935 var = child_get_env(tmpenv, "PATH"); 936 if (var != NULL) 937 child_set_env(env, envsize, "PATH", var); 938 939 if ((var = child_get_env(tmpenv, "UMASK")) != NULL) 940 if (sscanf(var, "%5lo", &mask) == 1) 941 umask((mode_t)mask); 942 943 for (i = 0; tmpenv[i] != NULL; i++) 944 free(tmpenv[i]); 945 free(tmpenv); 946 } 947 #endif /* HAVE_ETC_DEFAULT_LOGIN */ 948 949 #if defined(USE_PAM) || defined(HAVE_CYGWIN) 950 static void 951 copy_environment_blacklist(char **source, char ***env, u_int *envsize, 952 const char *blacklist) 953 { 954 char *var_name, *var_val; 955 int i; 956 957 if (source == NULL) 958 return; 959 960 for(i = 0; source[i] != NULL; i++) { 961 var_name = xstrdup(source[i]); 962 if ((var_val = strstr(var_name, "=")) == NULL) { 963 free(var_name); 964 continue; 965 } 966 *var_val++ = '\0'; 967 968 if (blacklist == NULL || 969 match_pattern_list(var_name, blacklist, 0) != 1) { 970 debug3("Copy environment: %s=%s", var_name, var_val); 971 child_set_env(env, envsize, var_name, var_val); 972 } 973 974 free(var_name); 975 } 976 } 977 #endif /* defined(USE_PAM) || defined(HAVE_CYGWIN) */ 978 979 #ifdef HAVE_CYGWIN 980 static void 981 copy_environment(char **source, char ***env, u_int *envsize) 982 { 983 copy_environment_blacklist(source, env, envsize, NULL); 984 } 985 #endif 986 987 static char ** 988 do_setup_env(struct ssh *ssh, Session *s, const char *shell) 989 { 990 char buf[256]; 991 size_t n; 992 u_int i, envsize; 993 char *ocp, *cp, *value, **env, *laddr; 994 struct passwd *pw = s->pw; 995 #if !defined (HAVE_LOGIN_CAP) && !defined (HAVE_CYGWIN) 996 char *path = NULL; 997 #endif 998 999 /* Initialize the environment. */ 1000 envsize = 100; 1001 env = xcalloc(envsize, sizeof(char *)); 1002 env[0] = NULL; 1003 1004 #ifdef HAVE_CYGWIN 1005 /* 1006 * The Windows environment contains some setting which are 1007 * important for a running system. They must not be dropped. 1008 */ 1009 { 1010 char **p; 1011 1012 p = fetch_windows_environment(); 1013 copy_environment(p, &env, &envsize); 1014 free_windows_environment(p); 1015 } 1016 #endif 1017 1018 #ifdef GSSAPI 1019 /* Allow any GSSAPI methods that we've used to alter 1020 * the child's environment as they see fit 1021 */ 1022 ssh_gssapi_do_child(&env, &envsize); 1023 #endif 1024 1025 /* Set basic environment. */ 1026 for (i = 0; i < s->num_env; i++) 1027 child_set_env(&env, &envsize, s->env[i].name, s->env[i].val); 1028 1029 child_set_env(&env, &envsize, "USER", pw->pw_name); 1030 child_set_env(&env, &envsize, "LOGNAME", pw->pw_name); 1031 #ifdef _AIX 1032 child_set_env(&env, &envsize, "LOGIN", pw->pw_name); 1033 #endif 1034 child_set_env(&env, &envsize, "HOME", pw->pw_dir); 1035 #ifdef HAVE_LOGIN_CAP 1036 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETPATH) < 0) 1037 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); 1038 else 1039 child_set_env(&env, &envsize, "PATH", getenv("PATH")); 1040 #else /* HAVE_LOGIN_CAP */ 1041 # ifndef HAVE_CYGWIN 1042 /* 1043 * There's no standard path on Windows. The path contains 1044 * important components pointing to the system directories, 1045 * needed for loading shared libraries. So the path better 1046 * remains intact here. 1047 */ 1048 # ifdef HAVE_ETC_DEFAULT_LOGIN 1049 read_etc_default_login(&env, &envsize, pw->pw_uid); 1050 path = child_get_env(env, "PATH"); 1051 # endif /* HAVE_ETC_DEFAULT_LOGIN */ 1052 if (path == NULL || *path == '\0') { 1053 child_set_env(&env, &envsize, "PATH", 1054 s->pw->pw_uid == 0 ? SUPERUSER_PATH : _PATH_STDPATH); 1055 } 1056 # endif /* HAVE_CYGWIN */ 1057 #endif /* HAVE_LOGIN_CAP */ 1058 1059 if (!options.use_pam) { 1060 snprintf(buf, sizeof buf, "%.200s/%.50s", 1061 _PATH_MAILDIR, pw->pw_name); 1062 child_set_env(&env, &envsize, "MAIL", buf); 1063 } 1064 1065 /* Normal systems set SHELL by default. */ 1066 child_set_env(&env, &envsize, "SHELL", shell); 1067 1068 if (getenv("TZ")) 1069 child_set_env(&env, &envsize, "TZ", getenv("TZ")); 1070 if (s->term) 1071 child_set_env(&env, &envsize, "TERM", s->term); 1072 if (s->display) 1073 child_set_env(&env, &envsize, "DISPLAY", s->display); 1074 1075 /* 1076 * Since we clear KRB5CCNAME at startup, if it's set now then it 1077 * must have been set by a native authentication method (eg AIX or 1078 * SIA), so copy it to the child. 1079 */ 1080 { 1081 char *cp; 1082 1083 if ((cp = getenv("KRB5CCNAME")) != NULL) 1084 child_set_env(&env, &envsize, "KRB5CCNAME", cp); 1085 } 1086 1087 #ifdef _AIX 1088 { 1089 char *cp; 1090 1091 if ((cp = getenv("AUTHSTATE")) != NULL) 1092 child_set_env(&env, &envsize, "AUTHSTATE", cp); 1093 read_environment_file(&env, &envsize, "/etc/environment", 1094 options.permit_user_env_whitelist); 1095 } 1096 #endif 1097 #ifdef KRB5 1098 if (s->authctxt->krb5_ccname) 1099 child_set_env(&env, &envsize, "KRB5CCNAME", 1100 s->authctxt->krb5_ccname); 1101 #endif 1102 if (auth_sock_name != NULL) 1103 child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME, 1104 auth_sock_name); 1105 1106 1107 /* Set custom environment options from pubkey authentication. */ 1108 if (options.permit_user_env) { 1109 for (n = 0 ; n < auth_opts->nenv; n++) { 1110 ocp = xstrdup(auth_opts->env[n]); 1111 cp = strchr(ocp, '='); 1112 if (*cp == '=') { 1113 *cp = '\0'; 1114 /* Apply PermitUserEnvironment whitelist */ 1115 if (options.permit_user_env_whitelist == NULL || 1116 match_pattern_list(ocp, 1117 options.permit_user_env_whitelist, 0) == 1) 1118 child_set_env(&env, &envsize, 1119 ocp, cp + 1); 1120 } 1121 free(ocp); 1122 } 1123 } 1124 1125 /* read $HOME/.ssh/environment. */ 1126 if (options.permit_user_env) { 1127 snprintf(buf, sizeof buf, "%.200s/.ssh/environment", 1128 pw->pw_dir); 1129 read_environment_file(&env, &envsize, buf, 1130 options.permit_user_env_whitelist); 1131 } 1132 1133 #ifdef USE_PAM 1134 /* 1135 * Pull in any environment variables that may have 1136 * been set by PAM. 1137 */ 1138 if (options.use_pam) { 1139 char **p; 1140 1141 /* 1142 * Don't allow PAM-internal env vars to leak 1143 * back into the session environment. 1144 */ 1145 #define PAM_ENV_BLACKLIST "SSH_AUTH_INFO*,SSH_CONNECTION*" 1146 p = fetch_pam_child_environment(); 1147 copy_environment_blacklist(p, &env, &envsize, 1148 PAM_ENV_BLACKLIST); 1149 free_pam_environment(p); 1150 1151 p = fetch_pam_environment(); 1152 copy_environment_blacklist(p, &env, &envsize, 1153 PAM_ENV_BLACKLIST); 1154 free_pam_environment(p); 1155 } 1156 #endif /* USE_PAM */ 1157 1158 /* Environment specified by admin */ 1159 for (i = 0; i < options.num_setenv; i++) { 1160 cp = xstrdup(options.setenv[i]); 1161 if ((value = strchr(cp, '=')) == NULL) { 1162 /* shouldn't happen; vars are checked in servconf.c */ 1163 fatal("Invalid config SetEnv: %s", options.setenv[i]); 1164 } 1165 *value++ = '\0'; 1166 child_set_env(&env, &envsize, cp, value); 1167 } 1168 1169 /* SSH_CLIENT deprecated */ 1170 snprintf(buf, sizeof buf, "%.50s %d %d", 1171 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 1172 ssh_local_port(ssh)); 1173 child_set_env(&env, &envsize, "SSH_CLIENT", buf); 1174 1175 laddr = get_local_ipaddr(ssh_packet_get_connection_in(ssh)); 1176 snprintf(buf, sizeof buf, "%.50s %d %.50s %d", 1177 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 1178 laddr, ssh_local_port(ssh)); 1179 free(laddr); 1180 child_set_env(&env, &envsize, "SSH_CONNECTION", buf); 1181 1182 if (tun_fwd_ifnames != NULL) 1183 child_set_env(&env, &envsize, "SSH_TUNNEL", tun_fwd_ifnames); 1184 if (auth_info_file != NULL) 1185 child_set_env(&env, &envsize, "SSH_USER_AUTH", auth_info_file); 1186 if (s->ttyfd != -1) 1187 child_set_env(&env, &envsize, "SSH_TTY", s->tty); 1188 if (original_command) 1189 child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND", 1190 original_command); 1191 1192 if (debug_flag) { 1193 /* dump the environment */ 1194 fprintf(stderr, "Environment:\n"); 1195 for (i = 0; env[i]; i++) 1196 fprintf(stderr, " %.200s\n", env[i]); 1197 } 1198 return env; 1199 } 1200 1201 /* 1202 * Run $HOME/.ssh/rc, /etc/ssh/sshrc, or xauth (whichever is found 1203 * first in this order). 1204 */ 1205 static void 1206 do_rc_files(struct ssh *ssh, Session *s, const char *shell) 1207 { 1208 FILE *f = NULL; 1209 char cmd[1024]; 1210 int do_xauth; 1211 struct stat st; 1212 1213 do_xauth = 1214 s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL; 1215 1216 /* ignore _PATH_SSH_USER_RC for subsystems and admin forced commands */ 1217 if (!s->is_subsystem && options.adm_forced_command == NULL && 1218 auth_opts->permit_user_rc && options.permit_user_rc && 1219 stat(_PATH_SSH_USER_RC, &st) >= 0) { 1220 snprintf(cmd, sizeof cmd, "%s -c '%s %s'", 1221 shell, _PATH_BSHELL, _PATH_SSH_USER_RC); 1222 if (debug_flag) 1223 fprintf(stderr, "Running %s\n", cmd); 1224 f = popen(cmd, "w"); 1225 if (f) { 1226 if (do_xauth) 1227 fprintf(f, "%s %s\n", s->auth_proto, 1228 s->auth_data); 1229 pclose(f); 1230 } else 1231 fprintf(stderr, "Could not run %s\n", 1232 _PATH_SSH_USER_RC); 1233 } else if (stat(_PATH_SSH_SYSTEM_RC, &st) >= 0) { 1234 if (debug_flag) 1235 fprintf(stderr, "Running %s %s\n", _PATH_BSHELL, 1236 _PATH_SSH_SYSTEM_RC); 1237 f = popen(_PATH_BSHELL " " _PATH_SSH_SYSTEM_RC, "w"); 1238 if (f) { 1239 if (do_xauth) 1240 fprintf(f, "%s %s\n", s->auth_proto, 1241 s->auth_data); 1242 pclose(f); 1243 } else 1244 fprintf(stderr, "Could not run %s\n", 1245 _PATH_SSH_SYSTEM_RC); 1246 } else if (do_xauth && options.xauth_location != NULL) { 1247 /* Add authority data to .Xauthority if appropriate. */ 1248 if (debug_flag) { 1249 fprintf(stderr, 1250 "Running %.500s remove %.100s\n", 1251 options.xauth_location, s->auth_display); 1252 fprintf(stderr, 1253 "%.500s add %.100s %.100s %.100s\n", 1254 options.xauth_location, s->auth_display, 1255 s->auth_proto, s->auth_data); 1256 } 1257 snprintf(cmd, sizeof cmd, "%s -q -", 1258 options.xauth_location); 1259 f = popen(cmd, "w"); 1260 if (f) { 1261 fprintf(f, "remove %s\n", 1262 s->auth_display); 1263 fprintf(f, "add %s %s %s\n", 1264 s->auth_display, s->auth_proto, 1265 s->auth_data); 1266 pclose(f); 1267 } else { 1268 fprintf(stderr, "Could not run %s\n", 1269 cmd); 1270 } 1271 } 1272 } 1273 1274 static void 1275 do_nologin(struct passwd *pw) 1276 { 1277 FILE *f = NULL; 1278 char buf[1024], *nl, *def_nl = _PATH_NOLOGIN; 1279 struct stat sb; 1280 1281 #ifdef HAVE_LOGIN_CAP 1282 if (login_getcapbool(lc, "ignorenologin", 0) || pw->pw_uid == 0) 1283 return; 1284 nl = login_getcapstr(lc, "nologin", def_nl, def_nl); 1285 #else 1286 if (pw->pw_uid == 0) 1287 return; 1288 nl = def_nl; 1289 #endif 1290 if (stat(nl, &sb) == -1) { 1291 if (nl != def_nl) 1292 free(nl); 1293 return; 1294 } 1295 1296 /* /etc/nologin exists. Print its contents if we can and exit. */ 1297 logit("User %.100s not allowed because %s exists", pw->pw_name, nl); 1298 if ((f = fopen(nl, "r")) != NULL) { 1299 while (fgets(buf, sizeof(buf), f)) 1300 fputs(buf, stderr); 1301 fclose(f); 1302 } 1303 exit(254); 1304 } 1305 1306 /* 1307 * Chroot into a directory after checking it for safety: all path components 1308 * must be root-owned directories with strict permissions. 1309 */ 1310 static void 1311 safely_chroot(const char *path, uid_t uid) 1312 { 1313 const char *cp; 1314 char component[PATH_MAX]; 1315 struct stat st; 1316 1317 if (!path_absolute(path)) 1318 fatal("chroot path does not begin at root"); 1319 if (strlen(path) >= sizeof(component)) 1320 fatal("chroot path too long"); 1321 1322 /* 1323 * Descend the path, checking that each component is a 1324 * root-owned directory with strict permissions. 1325 */ 1326 for (cp = path; cp != NULL;) { 1327 if ((cp = strchr(cp, '/')) == NULL) 1328 strlcpy(component, path, sizeof(component)); 1329 else { 1330 cp++; 1331 memcpy(component, path, cp - path); 1332 component[cp - path] = '\0'; 1333 } 1334 1335 debug3("%s: checking '%s'", __func__, component); 1336 1337 if (stat(component, &st) != 0) 1338 fatal("%s: stat(\"%s\"): %s", __func__, 1339 component, strerror(errno)); 1340 if (st.st_uid != 0 || (st.st_mode & 022) != 0) 1341 fatal("bad ownership or modes for chroot " 1342 "directory %s\"%s\"", 1343 cp == NULL ? "" : "component ", component); 1344 if (!S_ISDIR(st.st_mode)) 1345 fatal("chroot path %s\"%s\" is not a directory", 1346 cp == NULL ? "" : "component ", component); 1347 1348 } 1349 1350 if (chdir(path) == -1) 1351 fatal("Unable to chdir to chroot path \"%s\": " 1352 "%s", path, strerror(errno)); 1353 if (chroot(path) == -1) 1354 fatal("chroot(\"%s\"): %s", path, strerror(errno)); 1355 if (chdir("/") == -1) 1356 fatal("%s: chdir(/) after chroot: %s", 1357 __func__, strerror(errno)); 1358 verbose("Changed root directory to \"%s\"", path); 1359 } 1360 1361 /* Set login name, uid, gid, and groups. */ 1362 void 1363 do_setusercontext(struct passwd *pw) 1364 { 1365 char uidstr[32], *chroot_path, *tmp; 1366 1367 platform_setusercontext(pw); 1368 1369 if (platform_privileged_uidswap()) { 1370 #ifdef HAVE_LOGIN_CAP 1371 if (setusercontext(lc, pw, pw->pw_uid, 1372 (LOGIN_SETALL & ~(LOGIN_SETPATH|LOGIN_SETUSER))) < 0) { 1373 perror("unable to set user context"); 1374 exit(1); 1375 } 1376 #else 1377 if (setlogin(pw->pw_name) < 0) 1378 error("setlogin failed: %s", strerror(errno)); 1379 if (setgid(pw->pw_gid) < 0) { 1380 perror("setgid"); 1381 exit(1); 1382 } 1383 /* Initialize the group list. */ 1384 if (initgroups(pw->pw_name, pw->pw_gid) < 0) { 1385 perror("initgroups"); 1386 exit(1); 1387 } 1388 endgrent(); 1389 #endif 1390 1391 platform_setusercontext_post_groups(pw); 1392 1393 if (!in_chroot && options.chroot_directory != NULL && 1394 strcasecmp(options.chroot_directory, "none") != 0) { 1395 tmp = tilde_expand_filename(options.chroot_directory, 1396 pw->pw_uid); 1397 snprintf(uidstr, sizeof(uidstr), "%llu", 1398 (unsigned long long)pw->pw_uid); 1399 chroot_path = percent_expand(tmp, "h", pw->pw_dir, 1400 "u", pw->pw_name, "U", uidstr, (char *)NULL); 1401 safely_chroot(chroot_path, pw->pw_uid); 1402 free(tmp); 1403 free(chroot_path); 1404 /* Make sure we don't attempt to chroot again */ 1405 free(options.chroot_directory); 1406 options.chroot_directory = NULL; 1407 in_chroot = 1; 1408 } 1409 1410 #ifdef HAVE_LOGIN_CAP 1411 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUSER) < 0) { 1412 perror("unable to set user context (setuser)"); 1413 exit(1); 1414 } 1415 /* 1416 * FreeBSD's setusercontext() will not apply the user's 1417 * own umask setting unless running with the user's UID. 1418 */ 1419 (void) setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUMASK); 1420 #else 1421 # ifdef USE_LIBIAF 1422 /* 1423 * In a chroot environment, the set_id() will always fail; 1424 * typically because of the lack of necessary authentication 1425 * services and runtime such as ./usr/lib/libiaf.so, 1426 * ./usr/lib/libpam.so.1, and ./etc/passwd We skip it in the 1427 * internal sftp chroot case. We'll lose auditing and ACLs but 1428 * permanently_set_uid will take care of the rest. 1429 */ 1430 if (!in_chroot && set_id(pw->pw_name) != 0) 1431 fatal("set_id(%s) Failed", pw->pw_name); 1432 # endif /* USE_LIBIAF */ 1433 /* Permanently switch to the desired uid. */ 1434 permanently_set_uid(pw); 1435 #endif 1436 } else if (options.chroot_directory != NULL && 1437 strcasecmp(options.chroot_directory, "none") != 0) { 1438 fatal("server lacks privileges to chroot to ChrootDirectory"); 1439 } 1440 1441 if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) 1442 fatal("Failed to set uids to %u.", (u_int) pw->pw_uid); 1443 } 1444 1445 static void 1446 do_pwchange(Session *s) 1447 { 1448 fflush(NULL); 1449 fprintf(stderr, "WARNING: Your password has expired.\n"); 1450 if (s->ttyfd != -1) { 1451 fprintf(stderr, 1452 "You must change your password now and login again!\n"); 1453 #ifdef WITH_SELINUX 1454 setexeccon(NULL); 1455 #endif 1456 #ifdef PASSWD_NEEDS_USERNAME 1457 execl(_PATH_PASSWD_PROG, "passwd", s->pw->pw_name, 1458 (char *)NULL); 1459 #else 1460 execl(_PATH_PASSWD_PROG, "passwd", (char *)NULL); 1461 #endif 1462 perror("passwd"); 1463 } else { 1464 fprintf(stderr, 1465 "Password change required but no TTY available.\n"); 1466 } 1467 exit(1); 1468 } 1469 1470 static void 1471 child_close_fds(struct ssh *ssh) 1472 { 1473 extern int auth_sock; 1474 1475 if (auth_sock != -1) { 1476 close(auth_sock); 1477 auth_sock = -1; 1478 } 1479 1480 if (ssh_packet_get_connection_in(ssh) == 1481 ssh_packet_get_connection_out(ssh)) 1482 close(ssh_packet_get_connection_in(ssh)); 1483 else { 1484 close(ssh_packet_get_connection_in(ssh)); 1485 close(ssh_packet_get_connection_out(ssh)); 1486 } 1487 /* 1488 * Close all descriptors related to channels. They will still remain 1489 * open in the parent. 1490 */ 1491 /* XXX better use close-on-exec? -markus */ 1492 channel_close_all(ssh); 1493 1494 /* 1495 * Close any extra file descriptors. Note that there may still be 1496 * descriptors left by system functions. They will be closed later. 1497 */ 1498 endpwent(); 1499 1500 /* 1501 * Close any extra open file descriptors so that we don't have them 1502 * hanging around in clients. Note that we want to do this after 1503 * initgroups, because at least on Solaris 2.3 it leaves file 1504 * descriptors open. 1505 */ 1506 closefrom(STDERR_FILENO + 1); 1507 } 1508 1509 /* 1510 * Performs common processing for the child, such as setting up the 1511 * environment, closing extra file descriptors, setting the user and group 1512 * ids, and executing the command or shell. 1513 */ 1514 #define ARGV_MAX 10 1515 void 1516 do_child(struct ssh *ssh, Session *s, const char *command) 1517 { 1518 extern char **environ; 1519 char **env, *argv[ARGV_MAX], remote_id[512]; 1520 const char *shell, *shell0; 1521 struct passwd *pw = s->pw; 1522 int r = 0; 1523 1524 sshpkt_fmt_connection_id(ssh, remote_id, sizeof(remote_id)); 1525 1526 /* remove hostkey from the child's memory */ 1527 destroy_sensitive_data(); 1528 ssh_packet_clear_keys(ssh); 1529 1530 /* Force a password change */ 1531 if (s->authctxt->force_pwchange) { 1532 do_setusercontext(pw); 1533 child_close_fds(ssh); 1534 do_pwchange(s); 1535 exit(1); 1536 } 1537 1538 /* 1539 * Login(1) does this as well, and it needs uid 0 for the "-h" 1540 * switch, so we let login(1) to this for us. 1541 */ 1542 #ifdef HAVE_OSF_SIA 1543 session_setup_sia(pw, s->ttyfd == -1 ? NULL : s->tty); 1544 if (!check_quietlogin(s, command)) 1545 do_motd(); 1546 #else /* HAVE_OSF_SIA */ 1547 /* When PAM is enabled we rely on it to do the nologin check */ 1548 if (!options.use_pam) 1549 do_nologin(pw); 1550 do_setusercontext(pw); 1551 /* 1552 * PAM session modules in do_setusercontext may have 1553 * generated messages, so if this in an interactive 1554 * login then display them too. 1555 */ 1556 if (!check_quietlogin(s, command)) 1557 display_loginmsg(); 1558 #endif /* HAVE_OSF_SIA */ 1559 1560 #ifdef USE_PAM 1561 if (options.use_pam && !is_pam_session_open()) { 1562 debug3("PAM session not opened, exiting"); 1563 display_loginmsg(); 1564 exit(254); 1565 } 1566 #endif 1567 1568 /* 1569 * Get the shell from the password data. An empty shell field is 1570 * legal, and means /bin/sh. 1571 */ 1572 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; 1573 1574 /* 1575 * Make sure $SHELL points to the shell from the password file, 1576 * even if shell is overridden from login.conf 1577 */ 1578 env = do_setup_env(ssh, s, shell); 1579 1580 #ifdef HAVE_LOGIN_CAP 1581 shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell); 1582 #endif 1583 1584 /* 1585 * Close the connection descriptors; note that this is the child, and 1586 * the server will still have the socket open, and it is important 1587 * that we do not shutdown it. Note that the descriptors cannot be 1588 * closed before building the environment, as we call 1589 * ssh_remote_ipaddr there. 1590 */ 1591 child_close_fds(ssh); 1592 1593 /* 1594 * Must take new environment into use so that .ssh/rc, 1595 * /etc/ssh/sshrc and xauth are run in the proper environment. 1596 */ 1597 environ = env; 1598 1599 #if defined(KRB5) && defined(USE_AFS) 1600 /* 1601 * At this point, we check to see if AFS is active and if we have 1602 * a valid Kerberos 5 TGT. If so, it seems like a good idea to see 1603 * if we can (and need to) extend the ticket into an AFS token. If 1604 * we don't do this, we run into potential problems if the user's 1605 * home directory is in AFS and it's not world-readable. 1606 */ 1607 1608 if (options.kerberos_get_afs_token && k_hasafs() && 1609 (s->authctxt->krb5_ctx != NULL)) { 1610 char cell[64]; 1611 1612 debug("Getting AFS token"); 1613 1614 k_setpag(); 1615 1616 if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0) 1617 krb5_afslog(s->authctxt->krb5_ctx, 1618 s->authctxt->krb5_fwd_ccache, cell, NULL); 1619 1620 krb5_afslog_home(s->authctxt->krb5_ctx, 1621 s->authctxt->krb5_fwd_ccache, NULL, NULL, pw->pw_dir); 1622 } 1623 #endif 1624 1625 /* Change current directory to the user's home directory. */ 1626 if (chdir(pw->pw_dir) == -1) { 1627 /* Suppress missing homedir warning for chroot case */ 1628 #ifdef HAVE_LOGIN_CAP 1629 r = login_getcapbool(lc, "requirehome", 0); 1630 #endif 1631 if (r || !in_chroot) { 1632 fprintf(stderr, "Could not chdir to home " 1633 "directory %s: %s\n", pw->pw_dir, 1634 strerror(errno)); 1635 } 1636 if (r) 1637 exit(1); 1638 } 1639 1640 closefrom(STDERR_FILENO + 1); 1641 1642 do_rc_files(ssh, s, shell); 1643 1644 /* restore SIGPIPE for child */ 1645 ssh_signal(SIGPIPE, SIG_DFL); 1646 1647 if (s->is_subsystem == SUBSYSTEM_INT_SFTP_ERROR) { 1648 error("Connection from %s: refusing non-sftp session", 1649 remote_id); 1650 printf("This service allows sftp connections only.\n"); 1651 fflush(NULL); 1652 exit(1); 1653 } else if (s->is_subsystem == SUBSYSTEM_INT_SFTP) { 1654 extern int optind, optreset; 1655 int i; 1656 char *p, *args; 1657 1658 setproctitle("%s@%s", s->pw->pw_name, INTERNAL_SFTP_NAME); 1659 args = xstrdup(command ? command : "sftp-server"); 1660 for (i = 0, (p = strtok(args, " ")); p; (p = strtok(NULL, " "))) 1661 if (i < ARGV_MAX - 1) 1662 argv[i++] = p; 1663 argv[i] = NULL; 1664 optind = optreset = 1; 1665 __progname = argv[0]; 1666 #ifdef WITH_SELINUX 1667 ssh_selinux_change_context("sftpd_t"); 1668 #endif 1669 exit(sftp_server_main(i, argv, s->pw)); 1670 } 1671 1672 fflush(NULL); 1673 1674 /* Get the last component of the shell name. */ 1675 if ((shell0 = strrchr(shell, '/')) != NULL) 1676 shell0++; 1677 else 1678 shell0 = shell; 1679 1680 /* 1681 * If we have no command, execute the shell. In this case, the shell 1682 * name to be passed in argv[0] is preceded by '-' to indicate that 1683 * this is a login shell. 1684 */ 1685 if (!command) { 1686 char argv0[256]; 1687 1688 /* Start the shell. Set initial character to '-'. */ 1689 argv0[0] = '-'; 1690 1691 if (strlcpy(argv0 + 1, shell0, sizeof(argv0) - 1) 1692 >= sizeof(argv0) - 1) { 1693 errno = EINVAL; 1694 perror(shell); 1695 exit(1); 1696 } 1697 1698 /* Execute the shell. */ 1699 argv[0] = argv0; 1700 argv[1] = NULL; 1701 execve(shell, argv, env); 1702 1703 /* Executing the shell failed. */ 1704 perror(shell); 1705 exit(1); 1706 } 1707 /* 1708 * Execute the command using the user's shell. This uses the -c 1709 * option to execute the command. 1710 */ 1711 argv[0] = (char *) shell0; 1712 argv[1] = "-c"; 1713 argv[2] = (char *) command; 1714 argv[3] = NULL; 1715 execve(shell, argv, env); 1716 perror(shell); 1717 exit(1); 1718 } 1719 1720 void 1721 session_unused(int id) 1722 { 1723 debug3("%s: session id %d unused", __func__, id); 1724 if (id >= options.max_sessions || 1725 id >= sessions_nalloc) { 1726 fatal("%s: insane session id %d (max %d nalloc %d)", 1727 __func__, id, options.max_sessions, sessions_nalloc); 1728 } 1729 memset(&sessions[id], 0, sizeof(*sessions)); 1730 sessions[id].self = id; 1731 sessions[id].used = 0; 1732 sessions[id].chanid = -1; 1733 sessions[id].ptyfd = -1; 1734 sessions[id].ttyfd = -1; 1735 sessions[id].ptymaster = -1; 1736 sessions[id].x11_chanids = NULL; 1737 sessions[id].next_unused = sessions_first_unused; 1738 sessions_first_unused = id; 1739 } 1740 1741 Session * 1742 session_new(void) 1743 { 1744 Session *s, *tmp; 1745 1746 if (sessions_first_unused == -1) { 1747 if (sessions_nalloc >= options.max_sessions) 1748 return NULL; 1749 debug2("%s: allocate (allocated %d max %d)", 1750 __func__, sessions_nalloc, options.max_sessions); 1751 tmp = xrecallocarray(sessions, sessions_nalloc, 1752 sessions_nalloc + 1, sizeof(*sessions)); 1753 if (tmp == NULL) { 1754 error("%s: cannot allocate %d sessions", 1755 __func__, sessions_nalloc + 1); 1756 return NULL; 1757 } 1758 sessions = tmp; 1759 session_unused(sessions_nalloc++); 1760 } 1761 1762 if (sessions_first_unused >= sessions_nalloc || 1763 sessions_first_unused < 0) { 1764 fatal("%s: insane first_unused %d max %d nalloc %d", 1765 __func__, sessions_first_unused, options.max_sessions, 1766 sessions_nalloc); 1767 } 1768 1769 s = &sessions[sessions_first_unused]; 1770 if (s->used) { 1771 fatal("%s: session %d already used", 1772 __func__, sessions_first_unused); 1773 } 1774 sessions_first_unused = s->next_unused; 1775 s->used = 1; 1776 s->next_unused = -1; 1777 debug("session_new: session %d", s->self); 1778 1779 return s; 1780 } 1781 1782 static void 1783 session_dump(void) 1784 { 1785 int i; 1786 for (i = 0; i < sessions_nalloc; i++) { 1787 Session *s = &sessions[i]; 1788 1789 debug("dump: used %d next_unused %d session %d %p " 1790 "channel %d pid %ld", 1791 s->used, 1792 s->next_unused, 1793 s->self, 1794 s, 1795 s->chanid, 1796 (long)s->pid); 1797 } 1798 } 1799 1800 int 1801 session_open(Authctxt *authctxt, int chanid) 1802 { 1803 Session *s = session_new(); 1804 debug("session_open: channel %d", chanid); 1805 if (s == NULL) { 1806 error("no more sessions"); 1807 return 0; 1808 } 1809 s->authctxt = authctxt; 1810 s->pw = authctxt->pw; 1811 if (s->pw == NULL || !authctxt->valid) 1812 fatal("no user for session %d", s->self); 1813 debug("session_open: session %d: link with channel %d", s->self, chanid); 1814 s->chanid = chanid; 1815 return 1; 1816 } 1817 1818 Session * 1819 session_by_tty(char *tty) 1820 { 1821 int i; 1822 for (i = 0; i < sessions_nalloc; i++) { 1823 Session *s = &sessions[i]; 1824 if (s->used && s->ttyfd != -1 && strcmp(s->tty, tty) == 0) { 1825 debug("session_by_tty: session %d tty %s", i, tty); 1826 return s; 1827 } 1828 } 1829 debug("session_by_tty: unknown tty %.100s", tty); 1830 session_dump(); 1831 return NULL; 1832 } 1833 1834 static Session * 1835 session_by_channel(int id) 1836 { 1837 int i; 1838 for (i = 0; i < sessions_nalloc; i++) { 1839 Session *s = &sessions[i]; 1840 if (s->used && s->chanid == id) { 1841 debug("session_by_channel: session %d channel %d", 1842 i, id); 1843 return s; 1844 } 1845 } 1846 debug("session_by_channel: unknown channel %d", id); 1847 session_dump(); 1848 return NULL; 1849 } 1850 1851 static Session * 1852 session_by_x11_channel(int id) 1853 { 1854 int i, j; 1855 1856 for (i = 0; i < sessions_nalloc; i++) { 1857 Session *s = &sessions[i]; 1858 1859 if (s->x11_chanids == NULL || !s->used) 1860 continue; 1861 for (j = 0; s->x11_chanids[j] != -1; j++) { 1862 if (s->x11_chanids[j] == id) { 1863 debug("session_by_x11_channel: session %d " 1864 "channel %d", s->self, id); 1865 return s; 1866 } 1867 } 1868 } 1869 debug("session_by_x11_channel: unknown channel %d", id); 1870 session_dump(); 1871 return NULL; 1872 } 1873 1874 static Session * 1875 session_by_pid(pid_t pid) 1876 { 1877 int i; 1878 debug("session_by_pid: pid %ld", (long)pid); 1879 for (i = 0; i < sessions_nalloc; i++) { 1880 Session *s = &sessions[i]; 1881 if (s->used && s->pid == pid) 1882 return s; 1883 } 1884 error("session_by_pid: unknown pid %ld", (long)pid); 1885 session_dump(); 1886 return NULL; 1887 } 1888 1889 static int 1890 session_window_change_req(struct ssh *ssh, Session *s) 1891 { 1892 int r; 1893 1894 if ((r = sshpkt_get_u32(ssh, &s->col)) != 0 || 1895 (r = sshpkt_get_u32(ssh, &s->row)) != 0 || 1896 (r = sshpkt_get_u32(ssh, &s->xpixel)) != 0 || 1897 (r = sshpkt_get_u32(ssh, &s->ypixel)) != 0 || 1898 (r = sshpkt_get_end(ssh)) != 0) 1899 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 1900 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 1901 return 1; 1902 } 1903 1904 static int 1905 session_pty_req(struct ssh *ssh, Session *s) 1906 { 1907 int r; 1908 1909 if (!auth_opts->permit_pty_flag || !options.permit_tty) { 1910 debug("Allocating a pty not permitted for this connection."); 1911 return 0; 1912 } 1913 if (s->ttyfd != -1) { 1914 ssh_packet_disconnect(ssh, "Protocol error: you already have a pty."); 1915 return 0; 1916 } 1917 1918 if ((r = sshpkt_get_cstring(ssh, &s->term, NULL)) != 0 || 1919 (r = sshpkt_get_u32(ssh, &s->col)) != 0 || 1920 (r = sshpkt_get_u32(ssh, &s->row)) != 0 || 1921 (r = sshpkt_get_u32(ssh, &s->xpixel)) != 0 || 1922 (r = sshpkt_get_u32(ssh, &s->ypixel)) != 0) 1923 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 1924 1925 if (strcmp(s->term, "") == 0) { 1926 free(s->term); 1927 s->term = NULL; 1928 } 1929 1930 /* Allocate a pty and open it. */ 1931 debug("Allocating pty."); 1932 if (!PRIVSEP(pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, 1933 sizeof(s->tty)))) { 1934 free(s->term); 1935 s->term = NULL; 1936 s->ptyfd = -1; 1937 s->ttyfd = -1; 1938 error("session_pty_req: session %d alloc failed", s->self); 1939 return 0; 1940 } 1941 debug("session_pty_req: session %d alloc %s", s->self, s->tty); 1942 1943 ssh_tty_parse_modes(ssh, s->ttyfd); 1944 1945 if ((r = sshpkt_get_end(ssh)) != 0) 1946 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 1947 1948 if (!use_privsep) 1949 pty_setowner(s->pw, s->tty); 1950 1951 /* Set window size from the packet. */ 1952 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 1953 1954 session_proctitle(s); 1955 return 1; 1956 } 1957 1958 static int 1959 session_subsystem_req(struct ssh *ssh, Session *s) 1960 { 1961 struct stat st; 1962 int r, success = 0; 1963 char *prog, *cmd; 1964 u_int i; 1965 1966 if ((r = sshpkt_get_cstring(ssh, &s->subsys, NULL)) != 0 || 1967 (r = sshpkt_get_end(ssh)) != 0) 1968 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 1969 debug2("subsystem request for %.100s by user %s", s->subsys, 1970 s->pw->pw_name); 1971 1972 for (i = 0; i < options.num_subsystems; i++) { 1973 if (strcmp(s->subsys, options.subsystem_name[i]) == 0) { 1974 prog = options.subsystem_command[i]; 1975 cmd = options.subsystem_args[i]; 1976 if (strcmp(INTERNAL_SFTP_NAME, prog) == 0) { 1977 s->is_subsystem = SUBSYSTEM_INT_SFTP; 1978 debug("subsystem: %s", prog); 1979 } else { 1980 if (stat(prog, &st) == -1) 1981 debug("subsystem: cannot stat %s: %s", 1982 prog, strerror(errno)); 1983 s->is_subsystem = SUBSYSTEM_EXT; 1984 debug("subsystem: exec() %s", cmd); 1985 } 1986 success = do_exec(ssh, s, cmd) == 0; 1987 break; 1988 } 1989 } 1990 1991 if (!success) 1992 logit("subsystem request for %.100s by user %s failed, " 1993 "subsystem not found", s->subsys, s->pw->pw_name); 1994 1995 return success; 1996 } 1997 1998 static int 1999 session_x11_req(struct ssh *ssh, Session *s) 2000 { 2001 int r, success; 2002 u_char single_connection = 0; 2003 2004 if (s->auth_proto != NULL || s->auth_data != NULL) { 2005 error("session_x11_req: session %d: " 2006 "x11 forwarding already active", s->self); 2007 return 0; 2008 } 2009 if ((r = sshpkt_get_u8(ssh, &single_connection)) != 0 || 2010 (r = sshpkt_get_cstring(ssh, &s->auth_proto, NULL)) != 0 || 2011 (r = sshpkt_get_cstring(ssh, &s->auth_data, NULL)) != 0 || 2012 (r = sshpkt_get_u32(ssh, &s->screen)) != 0 || 2013 (r = sshpkt_get_end(ssh)) != 0) 2014 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 2015 2016 s->single_connection = single_connection; 2017 2018 if (xauth_valid_string(s->auth_proto) && 2019 xauth_valid_string(s->auth_data)) 2020 success = session_setup_x11fwd(ssh, s); 2021 else { 2022 success = 0; 2023 error("Invalid X11 forwarding data"); 2024 } 2025 if (!success) { 2026 free(s->auth_proto); 2027 free(s->auth_data); 2028 s->auth_proto = NULL; 2029 s->auth_data = NULL; 2030 } 2031 return success; 2032 } 2033 2034 static int 2035 session_shell_req(struct ssh *ssh, Session *s) 2036 { 2037 int r; 2038 2039 if ((r = sshpkt_get_end(ssh)) != 0) 2040 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 2041 return do_exec(ssh, s, NULL) == 0; 2042 } 2043 2044 static int 2045 session_exec_req(struct ssh *ssh, Session *s) 2046 { 2047 u_int success; 2048 int r; 2049 char *command = NULL; 2050 2051 if ((r = sshpkt_get_cstring(ssh, &command, NULL)) != 0 || 2052 (r = sshpkt_get_end(ssh)) != 0) 2053 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 2054 2055 success = do_exec(ssh, s, command) == 0; 2056 free(command); 2057 return success; 2058 } 2059 2060 static int 2061 session_break_req(struct ssh *ssh, Session *s) 2062 { 2063 int r; 2064 2065 if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* ignore */ 2066 (r = sshpkt_get_end(ssh)) != 0) 2067 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 2068 2069 if (s->ptymaster == -1 || tcsendbreak(s->ptymaster, 0) == -1) 2070 return 0; 2071 return 1; 2072 } 2073 2074 static int 2075 session_env_req(struct ssh *ssh, Session *s) 2076 { 2077 char *name, *val; 2078 u_int i; 2079 int r; 2080 2081 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 || 2082 (r = sshpkt_get_cstring(ssh, &val, NULL)) != 0 || 2083 (r = sshpkt_get_end(ssh)) != 0) 2084 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 2085 2086 /* Don't set too many environment variables */ 2087 if (s->num_env > 128) { 2088 debug2("Ignoring env request %s: too many env vars", name); 2089 goto fail; 2090 } 2091 2092 for (i = 0; i < options.num_accept_env; i++) { 2093 if (match_pattern(name, options.accept_env[i])) { 2094 debug2("Setting env %d: %s=%s", s->num_env, name, val); 2095 s->env = xrecallocarray(s->env, s->num_env, 2096 s->num_env + 1, sizeof(*s->env)); 2097 s->env[s->num_env].name = name; 2098 s->env[s->num_env].val = val; 2099 s->num_env++; 2100 return (1); 2101 } 2102 } 2103 debug2("Ignoring env request %s: disallowed name", name); 2104 2105 fail: 2106 free(name); 2107 free(val); 2108 return (0); 2109 } 2110 2111 /* 2112 * Conversion of signals from ssh channel request names. 2113 * Subset of signals from RFC 4254 section 6.10C, with SIGINFO as 2114 * local extension. 2115 */ 2116 static int 2117 name2sig(char *name) 2118 { 2119 #define SSH_SIG(x) if (strcmp(name, #x) == 0) return SIG ## x 2120 SSH_SIG(HUP); 2121 SSH_SIG(INT); 2122 SSH_SIG(KILL); 2123 SSH_SIG(QUIT); 2124 SSH_SIG(TERM); 2125 SSH_SIG(USR1); 2126 SSH_SIG(USR2); 2127 #undef SSH_SIG 2128 #ifdef SIGINFO 2129 if (strcmp(name, "INFO@openssh.com") == 0) 2130 return SIGINFO; 2131 #endif 2132 return -1; 2133 } 2134 2135 static int 2136 session_signal_req(struct ssh *ssh, Session *s) 2137 { 2138 char *signame = NULL; 2139 int r, sig, success = 0; 2140 2141 if ((r = sshpkt_get_cstring(ssh, &signame, NULL)) != 0 || 2142 (r = sshpkt_get_end(ssh)) != 0) { 2143 error("%s: parse packet: %s", __func__, ssh_err(r)); 2144 goto out; 2145 } 2146 if ((sig = name2sig(signame)) == -1) { 2147 error("%s: unsupported signal \"%s\"", __func__, signame); 2148 goto out; 2149 } 2150 if (s->pid <= 0) { 2151 error("%s: no pid for session %d", __func__, s->self); 2152 goto out; 2153 } 2154 if (s->forced || s->is_subsystem) { 2155 error("%s: refusing to send signal %s to %s session", __func__, 2156 signame, s->forced ? "forced-command" : "subsystem"); 2157 goto out; 2158 } 2159 if (!use_privsep || mm_is_monitor()) { 2160 error("%s: session signalling requires privilege separation", 2161 __func__); 2162 goto out; 2163 } 2164 2165 debug("%s: signal %s, killpg(%ld, %d)", __func__, signame, 2166 (long)s->pid, sig); 2167 temporarily_use_uid(s->pw); 2168 r = killpg(s->pid, sig); 2169 restore_uid(); 2170 if (r != 0) { 2171 error("%s: killpg(%ld, %d): %s", __func__, (long)s->pid, 2172 sig, strerror(errno)); 2173 goto out; 2174 } 2175 2176 /* success */ 2177 success = 1; 2178 out: 2179 free(signame); 2180 return success; 2181 } 2182 2183 static int 2184 session_auth_agent_req(struct ssh *ssh, Session *s) 2185 { 2186 static int called = 0; 2187 int r; 2188 2189 if ((r = sshpkt_get_end(ssh)) != 0) 2190 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 2191 if (!auth_opts->permit_agent_forwarding_flag || 2192 !options.allow_agent_forwarding) { 2193 debug("%s: agent forwarding disabled", __func__); 2194 return 0; 2195 } 2196 if (called) { 2197 return 0; 2198 } else { 2199 called = 1; 2200 return auth_input_request_forwarding(ssh, s->pw); 2201 } 2202 } 2203 2204 int 2205 session_input_channel_req(struct ssh *ssh, Channel *c, const char *rtype) 2206 { 2207 int success = 0; 2208 Session *s; 2209 2210 if ((s = session_by_channel(c->self)) == NULL) { 2211 logit("%s: no session %d req %.100s", __func__, c->self, rtype); 2212 return 0; 2213 } 2214 debug("%s: session %d req %s", __func__, s->self, rtype); 2215 2216 /* 2217 * a session is in LARVAL state until a shell, a command 2218 * or a subsystem is executed 2219 */ 2220 if (c->type == SSH_CHANNEL_LARVAL) { 2221 if (strcmp(rtype, "shell") == 0) { 2222 success = session_shell_req(ssh, s); 2223 } else if (strcmp(rtype, "exec") == 0) { 2224 success = session_exec_req(ssh, s); 2225 } else if (strcmp(rtype, "pty-req") == 0) { 2226 success = session_pty_req(ssh, s); 2227 } else if (strcmp(rtype, "x11-req") == 0) { 2228 success = session_x11_req(ssh, s); 2229 } else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) { 2230 success = session_auth_agent_req(ssh, s); 2231 } else if (strcmp(rtype, "subsystem") == 0) { 2232 success = session_subsystem_req(ssh, s); 2233 } else if (strcmp(rtype, "env") == 0) { 2234 success = session_env_req(ssh, s); 2235 } 2236 } 2237 if (strcmp(rtype, "window-change") == 0) { 2238 success = session_window_change_req(ssh, s); 2239 } else if (strcmp(rtype, "break") == 0) { 2240 success = session_break_req(ssh, s); 2241 } else if (strcmp(rtype, "signal") == 0) { 2242 success = session_signal_req(ssh, s); 2243 } 2244 2245 return success; 2246 } 2247 2248 void 2249 session_set_fds(struct ssh *ssh, Session *s, 2250 int fdin, int fdout, int fderr, int ignore_fderr, int is_tty) 2251 { 2252 /* 2253 * now that have a child and a pipe to the child, 2254 * we can activate our channel and register the fd's 2255 */ 2256 if (s->chanid == -1) 2257 fatal("no channel for session %d", s->self); 2258 channel_set_fds(ssh, s->chanid, 2259 fdout, fdin, fderr, 2260 ignore_fderr ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ, 2261 1, is_tty, CHAN_SES_WINDOW_DEFAULT); 2262 } 2263 2264 /* 2265 * Function to perform pty cleanup. Also called if we get aborted abnormally 2266 * (e.g., due to a dropped connection). 2267 */ 2268 void 2269 session_pty_cleanup2(Session *s) 2270 { 2271 if (s == NULL) { 2272 error("%s: no session", __func__); 2273 return; 2274 } 2275 if (s->ttyfd == -1) 2276 return; 2277 2278 debug("%s: session %d release %s", __func__, s->self, s->tty); 2279 2280 /* Record that the user has logged out. */ 2281 if (s->pid != 0) 2282 record_logout(s->pid, s->tty, s->pw->pw_name); 2283 2284 /* Release the pseudo-tty. */ 2285 if (getuid() == 0) 2286 pty_release(s->tty); 2287 2288 /* 2289 * Close the server side of the socket pairs. We must do this after 2290 * the pty cleanup, so that another process doesn't get this pty 2291 * while we're still cleaning up. 2292 */ 2293 if (s->ptymaster != -1 && close(s->ptymaster) == -1) 2294 error("close(s->ptymaster/%d): %s", 2295 s->ptymaster, strerror(errno)); 2296 2297 /* unlink pty from session */ 2298 s->ttyfd = -1; 2299 } 2300 2301 void 2302 session_pty_cleanup(Session *s) 2303 { 2304 PRIVSEP(session_pty_cleanup2(s)); 2305 } 2306 2307 static char * 2308 sig2name(int sig) 2309 { 2310 #define SSH_SIG(x) if (sig == SIG ## x) return #x 2311 SSH_SIG(ABRT); 2312 SSH_SIG(ALRM); 2313 SSH_SIG(FPE); 2314 SSH_SIG(HUP); 2315 SSH_SIG(ILL); 2316 SSH_SIG(INT); 2317 SSH_SIG(KILL); 2318 SSH_SIG(PIPE); 2319 SSH_SIG(QUIT); 2320 SSH_SIG(SEGV); 2321 SSH_SIG(TERM); 2322 SSH_SIG(USR1); 2323 SSH_SIG(USR2); 2324 #undef SSH_SIG 2325 return "SIG@openssh.com"; 2326 } 2327 2328 static void 2329 session_close_x11(struct ssh *ssh, int id) 2330 { 2331 Channel *c; 2332 2333 if ((c = channel_by_id(ssh, id)) == NULL) { 2334 debug("%s: x11 channel %d missing", __func__, id); 2335 } else { 2336 /* Detach X11 listener */ 2337 debug("%s: detach x11 channel %d", __func__, id); 2338 channel_cancel_cleanup(ssh, id); 2339 if (c->ostate != CHAN_OUTPUT_CLOSED) 2340 chan_mark_dead(ssh, c); 2341 } 2342 } 2343 2344 static void 2345 session_close_single_x11(struct ssh *ssh, int id, void *arg) 2346 { 2347 Session *s; 2348 u_int i; 2349 2350 debug3("%s: channel %d", __func__, id); 2351 channel_cancel_cleanup(ssh, id); 2352 if ((s = session_by_x11_channel(id)) == NULL) 2353 fatal("%s: no x11 channel %d", __func__, id); 2354 for (i = 0; s->x11_chanids[i] != -1; i++) { 2355 debug("%s: session %d: closing channel %d", 2356 __func__, s->self, s->x11_chanids[i]); 2357 /* 2358 * The channel "id" is already closing, but make sure we 2359 * close all of its siblings. 2360 */ 2361 if (s->x11_chanids[i] != id) 2362 session_close_x11(ssh, s->x11_chanids[i]); 2363 } 2364 free(s->x11_chanids); 2365 s->x11_chanids = NULL; 2366 free(s->display); 2367 s->display = NULL; 2368 free(s->auth_proto); 2369 s->auth_proto = NULL; 2370 free(s->auth_data); 2371 s->auth_data = NULL; 2372 free(s->auth_display); 2373 s->auth_display = NULL; 2374 } 2375 2376 static void 2377 session_exit_message(struct ssh *ssh, Session *s, int status) 2378 { 2379 Channel *c; 2380 int r; 2381 2382 if ((c = channel_lookup(ssh, s->chanid)) == NULL) 2383 fatal("%s: session %d: no channel %d", 2384 __func__, s->self, s->chanid); 2385 debug("%s: session %d channel %d pid %ld", 2386 __func__, s->self, s->chanid, (long)s->pid); 2387 2388 if (WIFEXITED(status)) { 2389 channel_request_start(ssh, s->chanid, "exit-status", 0); 2390 if ((r = sshpkt_put_u32(ssh, WEXITSTATUS(status))) != 0 || 2391 (r = sshpkt_send(ssh)) != 0) 2392 sshpkt_fatal(ssh, r, "%s: exit reply", __func__); 2393 } else if (WIFSIGNALED(status)) { 2394 channel_request_start(ssh, s->chanid, "exit-signal", 0); 2395 #ifndef WCOREDUMP 2396 # define WCOREDUMP(x) (0) 2397 #endif 2398 if ((r = sshpkt_put_cstring(ssh, sig2name(WTERMSIG(status)))) != 0 || 2399 (r = sshpkt_put_u8(ssh, WCOREDUMP(status)? 1 : 0)) != 0 || 2400 (r = sshpkt_put_cstring(ssh, "")) != 0 || 2401 (r = sshpkt_put_cstring(ssh, "")) != 0 || 2402 (r = sshpkt_send(ssh)) != 0) 2403 sshpkt_fatal(ssh, r, "%s: exit reply", __func__); 2404 } else { 2405 /* Some weird exit cause. Just exit. */ 2406 ssh_packet_disconnect(ssh, "wait returned status %04x.", status); 2407 } 2408 2409 /* disconnect channel */ 2410 debug("%s: release channel %d", __func__, s->chanid); 2411 2412 /* 2413 * Adjust cleanup callback attachment to send close messages when 2414 * the channel gets EOF. The session will be then be closed 2415 * by session_close_by_channel when the child sessions close their fds. 2416 */ 2417 channel_register_cleanup(ssh, c->self, session_close_by_channel, 1); 2418 2419 /* 2420 * emulate a write failure with 'chan_write_failed', nobody will be 2421 * interested in data we write. 2422 * Note that we must not call 'chan_read_failed', since there could 2423 * be some more data waiting in the pipe. 2424 */ 2425 if (c->ostate != CHAN_OUTPUT_CLOSED) 2426 chan_write_failed(ssh, c); 2427 } 2428 2429 void 2430 session_close(struct ssh *ssh, Session *s) 2431 { 2432 u_int i; 2433 2434 verbose("Close session: user %s from %.200s port %d id %d", 2435 s->pw->pw_name, 2436 ssh_remote_ipaddr(ssh), 2437 ssh_remote_port(ssh), 2438 s->self); 2439 2440 if (s->ttyfd != -1) 2441 session_pty_cleanup(s); 2442 free(s->term); 2443 free(s->display); 2444 free(s->x11_chanids); 2445 free(s->auth_display); 2446 free(s->auth_data); 2447 free(s->auth_proto); 2448 free(s->subsys); 2449 if (s->env != NULL) { 2450 for (i = 0; i < s->num_env; i++) { 2451 free(s->env[i].name); 2452 free(s->env[i].val); 2453 } 2454 free(s->env); 2455 } 2456 session_proctitle(s); 2457 session_unused(s->self); 2458 } 2459 2460 void 2461 session_close_by_pid(struct ssh *ssh, pid_t pid, int status) 2462 { 2463 Session *s = session_by_pid(pid); 2464 if (s == NULL) { 2465 debug("%s: no session for pid %ld", __func__, (long)pid); 2466 return; 2467 } 2468 if (s->chanid != -1) 2469 session_exit_message(ssh, s, status); 2470 if (s->ttyfd != -1) 2471 session_pty_cleanup(s); 2472 s->pid = 0; 2473 } 2474 2475 /* 2476 * this is called when a channel dies before 2477 * the session 'child' itself dies 2478 */ 2479 void 2480 session_close_by_channel(struct ssh *ssh, int id, void *arg) 2481 { 2482 Session *s = session_by_channel(id); 2483 u_int i; 2484 2485 if (s == NULL) { 2486 debug("%s: no session for id %d", __func__, id); 2487 return; 2488 } 2489 debug("%s: channel %d child %ld", __func__, id, (long)s->pid); 2490 if (s->pid != 0) { 2491 debug("%s: channel %d: has child, ttyfd %d", 2492 __func__, id, s->ttyfd); 2493 /* 2494 * delay detach of session, but release pty, since 2495 * the fd's to the child are already closed 2496 */ 2497 if (s->ttyfd != -1) 2498 session_pty_cleanup(s); 2499 return; 2500 } 2501 /* detach by removing callback */ 2502 channel_cancel_cleanup(ssh, s->chanid); 2503 2504 /* Close any X11 listeners associated with this session */ 2505 if (s->x11_chanids != NULL) { 2506 for (i = 0; s->x11_chanids[i] != -1; i++) { 2507 session_close_x11(ssh, s->x11_chanids[i]); 2508 s->x11_chanids[i] = -1; 2509 } 2510 } 2511 2512 s->chanid = -1; 2513 session_close(ssh, s); 2514 } 2515 2516 void 2517 session_destroy_all(struct ssh *ssh, void (*closefunc)(Session *)) 2518 { 2519 int i; 2520 for (i = 0; i < sessions_nalloc; i++) { 2521 Session *s = &sessions[i]; 2522 if (s->used) { 2523 if (closefunc != NULL) 2524 closefunc(s); 2525 else 2526 session_close(ssh, s); 2527 } 2528 } 2529 } 2530 2531 static char * 2532 session_tty_list(void) 2533 { 2534 static char buf[1024]; 2535 int i; 2536 char *cp; 2537 2538 buf[0] = '\0'; 2539 for (i = 0; i < sessions_nalloc; i++) { 2540 Session *s = &sessions[i]; 2541 if (s->used && s->ttyfd != -1) { 2542 2543 if (strncmp(s->tty, "/dev/", 5) != 0) { 2544 cp = strrchr(s->tty, '/'); 2545 cp = (cp == NULL) ? s->tty : cp + 1; 2546 } else 2547 cp = s->tty + 5; 2548 2549 if (buf[0] != '\0') 2550 strlcat(buf, ",", sizeof buf); 2551 strlcat(buf, cp, sizeof buf); 2552 } 2553 } 2554 if (buf[0] == '\0') 2555 strlcpy(buf, "notty", sizeof buf); 2556 return buf; 2557 } 2558 2559 void 2560 session_proctitle(Session *s) 2561 { 2562 if (s->pw == NULL) 2563 error("no user for session %d", s->self); 2564 else 2565 setproctitle("%s@%s", s->pw->pw_name, session_tty_list()); 2566 } 2567 2568 int 2569 session_setup_x11fwd(struct ssh *ssh, Session *s) 2570 { 2571 struct stat st; 2572 char display[512], auth_display[512]; 2573 char hostname[NI_MAXHOST]; 2574 u_int i; 2575 2576 if (!auth_opts->permit_x11_forwarding_flag) { 2577 ssh_packet_send_debug(ssh, "X11 forwarding disabled by key options."); 2578 return 0; 2579 } 2580 if (!options.x11_forwarding) { 2581 debug("X11 forwarding disabled in server configuration file."); 2582 return 0; 2583 } 2584 if (options.xauth_location == NULL || 2585 (stat(options.xauth_location, &st) == -1)) { 2586 ssh_packet_send_debug(ssh, "No xauth program; cannot forward X11."); 2587 return 0; 2588 } 2589 if (s->display != NULL) { 2590 debug("X11 display already set."); 2591 return 0; 2592 } 2593 if (x11_create_display_inet(ssh, options.x11_display_offset, 2594 options.x11_use_localhost, s->single_connection, 2595 &s->display_number, &s->x11_chanids) == -1) { 2596 debug("x11_create_display_inet failed."); 2597 return 0; 2598 } 2599 for (i = 0; s->x11_chanids[i] != -1; i++) { 2600 channel_register_cleanup(ssh, s->x11_chanids[i], 2601 session_close_single_x11, 0); 2602 } 2603 2604 /* Set up a suitable value for the DISPLAY variable. */ 2605 if (gethostname(hostname, sizeof(hostname)) == -1) 2606 fatal("gethostname: %.100s", strerror(errno)); 2607 /* 2608 * auth_display must be used as the displayname when the 2609 * authorization entry is added with xauth(1). This will be 2610 * different than the DISPLAY string for localhost displays. 2611 */ 2612 if (options.x11_use_localhost) { 2613 snprintf(display, sizeof display, "localhost:%u.%u", 2614 s->display_number, s->screen); 2615 snprintf(auth_display, sizeof auth_display, "unix:%u.%u", 2616 s->display_number, s->screen); 2617 s->display = xstrdup(display); 2618 s->auth_display = xstrdup(auth_display); 2619 } else { 2620 #ifdef IPADDR_IN_DISPLAY 2621 struct hostent *he; 2622 struct in_addr my_addr; 2623 2624 he = gethostbyname(hostname); 2625 if (he == NULL) { 2626 error("Can't get IP address for X11 DISPLAY."); 2627 ssh_packet_send_debug(ssh, "Can't get IP address for X11 DISPLAY."); 2628 return 0; 2629 } 2630 memcpy(&my_addr, he->h_addr_list[0], sizeof(struct in_addr)); 2631 snprintf(display, sizeof display, "%.50s:%u.%u", inet_ntoa(my_addr), 2632 s->display_number, s->screen); 2633 #else 2634 snprintf(display, sizeof display, "%.400s:%u.%u", hostname, 2635 s->display_number, s->screen); 2636 #endif 2637 s->display = xstrdup(display); 2638 s->auth_display = xstrdup(display); 2639 } 2640 2641 return 1; 2642 } 2643 2644 static void 2645 do_authenticated2(struct ssh *ssh, Authctxt *authctxt) 2646 { 2647 server_loop2(ssh, authctxt); 2648 } 2649 2650 void 2651 do_cleanup(struct ssh *ssh, Authctxt *authctxt) 2652 { 2653 static int called = 0; 2654 2655 debug("do_cleanup"); 2656 2657 /* no cleanup if we're in the child for login shell */ 2658 if (is_child) 2659 return; 2660 2661 /* avoid double cleanup */ 2662 if (called) 2663 return; 2664 called = 1; 2665 2666 if (authctxt == NULL) 2667 return; 2668 2669 #ifdef USE_PAM 2670 if (options.use_pam) { 2671 sshpam_cleanup(); 2672 sshpam_thread_cleanup(); 2673 } 2674 #endif 2675 2676 if (!authctxt->authenticated) 2677 return; 2678 2679 #ifdef KRB5 2680 if (options.kerberos_ticket_cleanup && 2681 authctxt->krb5_ctx) 2682 krb5_cleanup_proc(authctxt); 2683 #endif 2684 2685 #ifdef GSSAPI 2686 if (options.gss_cleanup_creds) 2687 ssh_gssapi_cleanup_creds(); 2688 #endif 2689 2690 /* remove agent socket */ 2691 auth_sock_cleanup_proc(authctxt->pw); 2692 2693 /* remove userauth info */ 2694 if (auth_info_file != NULL) { 2695 temporarily_use_uid(authctxt->pw); 2696 unlink(auth_info_file); 2697 restore_uid(); 2698 free(auth_info_file); 2699 auth_info_file = NULL; 2700 } 2701 2702 /* 2703 * Cleanup ptys/utmp only if privsep is disabled, 2704 * or if running in monitor. 2705 */ 2706 if (!use_privsep || mm_is_monitor()) 2707 session_destroy_all(ssh, session_pty_cleanup2); 2708 } 2709 2710 /* Return a name for the remote host that fits inside utmp_size */ 2711 2712 const char * 2713 session_get_remote_name_or_ip(struct ssh *ssh, u_int utmp_size, int use_dns) 2714 { 2715 const char *remote = ""; 2716 2717 if (utmp_size > 0) 2718 remote = auth_get_canonical_hostname(ssh, use_dns); 2719 if (utmp_size == 0 || strlen(remote) > utmp_size) 2720 remote = ssh_remote_ipaddr(ssh); 2721 return remote; 2722 } 2723 2724