1 /* $OpenBSD: session.c,v 1.330 2022/02/08 08:59:12 dtucker Exp $ */ 2 /* 3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 4 * All rights reserved 5 * 6 * As far as I am concerned, the code I have written for this software 7 * can be used freely for any purpose. Any derived versions of this 8 * software must be clearly marked as such, and if the derived work is 9 * incompatible with the protocol description in the RFC file, it must be 10 * called by a name other than "ssh" or "Secure Shell". 11 * 12 * SSH2 support by Markus Friedl. 13 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 14 * 15 * Redistribution and use in source and binary forms, with or without 16 * modification, are permitted provided that the following conditions 17 * are met: 18 * 1. Redistributions of source code must retain the above copyright 19 * notice, this list of conditions and the following disclaimer. 20 * 2. Redistributions in binary form must reproduce the above copyright 21 * notice, this list of conditions and the following disclaimer in the 22 * documentation and/or other materials provided with the distribution. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 25 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 26 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 27 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 28 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 29 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 30 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 31 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 32 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 33 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 34 */ 35 36 #include "includes.h" 37 38 #include <sys/types.h> 39 #ifdef HAVE_SYS_STAT_H 40 # include <sys/stat.h> 41 #endif 42 #include <sys/socket.h> 43 #include <sys/un.h> 44 #include <sys/wait.h> 45 46 #include <arpa/inet.h> 47 48 #include <ctype.h> 49 #include <errno.h> 50 #include <fcntl.h> 51 #include <grp.h> 52 #include <netdb.h> 53 #ifdef HAVE_PATHS_H 54 #include <paths.h> 55 #endif 56 #include <pwd.h> 57 #include <signal.h> 58 #include <stdio.h> 59 #include <stdlib.h> 60 #include <string.h> 61 #include <stdarg.h> 62 #include <unistd.h> 63 #include <limits.h> 64 65 #include "openbsd-compat/sys-queue.h" 66 #include "xmalloc.h" 67 #include "ssh.h" 68 #include "ssh2.h" 69 #include "sshpty.h" 70 #include "packet.h" 71 #include "sshbuf.h" 72 #include "ssherr.h" 73 #include "match.h" 74 #include "uidswap.h" 75 #include "compat.h" 76 #include "channels.h" 77 #include "sshkey.h" 78 #include "cipher.h" 79 #ifdef GSSAPI 80 #include "ssh-gss.h" 81 #endif 82 #include "hostfile.h" 83 #include "auth.h" 84 #include "auth-options.h" 85 #include "authfd.h" 86 #include "pathnames.h" 87 #include "log.h" 88 #include "misc.h" 89 #include "servconf.h" 90 #include "sshlogin.h" 91 #include "serverloop.h" 92 #include "canohost.h" 93 #include "session.h" 94 #include "kex.h" 95 #include "monitor_wrap.h" 96 #include "sftp.h" 97 #include "atomicio.h" 98 99 #if defined(KRB5) && defined(USE_AFS) 100 #include <kafs.h> 101 #endif 102 103 #ifdef WITH_SELINUX 104 #include <selinux/selinux.h> 105 #endif 106 107 #define IS_INTERNAL_SFTP(c) \ 108 (!strncmp(c, INTERNAL_SFTP_NAME, sizeof(INTERNAL_SFTP_NAME) - 1) && \ 109 (c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\0' || \ 110 c[sizeof(INTERNAL_SFTP_NAME) - 1] == ' ' || \ 111 c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\t')) 112 113 /* func */ 114 115 Session *session_new(void); 116 void session_set_fds(struct ssh *, Session *, int, int, int, int, int); 117 void session_pty_cleanup(Session *); 118 void session_proctitle(Session *); 119 int session_setup_x11fwd(struct ssh *, Session *); 120 int do_exec_pty(struct ssh *, Session *, const char *); 121 int do_exec_no_pty(struct ssh *, Session *, const char *); 122 int do_exec(struct ssh *, Session *, const char *); 123 void do_login(struct ssh *, Session *, const char *); 124 void do_child(struct ssh *, Session *, const char *); 125 void do_motd(void); 126 int check_quietlogin(Session *, const char *); 127 128 static void do_authenticated2(struct ssh *, Authctxt *); 129 130 static int session_pty_req(struct ssh *, Session *); 131 132 /* import */ 133 extern ServerOptions options; 134 extern char *__progname; 135 extern int debug_flag; 136 extern u_int utmp_len; 137 extern int startup_pipe; 138 extern void destroy_sensitive_data(void); 139 extern struct sshbuf *loginmsg; 140 extern struct sshauthopt *auth_opts; 141 extern char *tun_fwd_ifnames; /* serverloop.c */ 142 143 /* original command from peer. */ 144 const char *original_command = NULL; 145 146 /* data */ 147 static int sessions_first_unused = -1; 148 static int sessions_nalloc = 0; 149 static Session *sessions = NULL; 150 151 #define SUBSYSTEM_NONE 0 152 #define SUBSYSTEM_EXT 1 153 #define SUBSYSTEM_INT_SFTP 2 154 #define SUBSYSTEM_INT_SFTP_ERROR 3 155 156 #ifdef HAVE_LOGIN_CAP 157 login_cap_t *lc; 158 #endif 159 160 static int is_child = 0; 161 static int in_chroot = 0; 162 163 /* File containing userauth info, if ExposeAuthInfo set */ 164 static char *auth_info_file = NULL; 165 166 /* Name and directory of socket for authentication agent forwarding. */ 167 static char *auth_sock_name = NULL; 168 static char *auth_sock_dir = NULL; 169 170 /* removes the agent forwarding socket */ 171 172 static void 173 auth_sock_cleanup_proc(struct passwd *pw) 174 { 175 if (auth_sock_name != NULL) { 176 temporarily_use_uid(pw); 177 unlink(auth_sock_name); 178 rmdir(auth_sock_dir); 179 auth_sock_name = NULL; 180 restore_uid(); 181 } 182 } 183 184 static int 185 auth_input_request_forwarding(struct ssh *ssh, struct passwd * pw) 186 { 187 Channel *nc; 188 int sock = -1; 189 190 if (auth_sock_name != NULL) { 191 error("authentication forwarding requested twice."); 192 return 0; 193 } 194 195 /* Temporarily drop privileged uid for mkdir/bind. */ 196 temporarily_use_uid(pw); 197 198 /* Allocate a buffer for the socket name, and format the name. */ 199 auth_sock_dir = xstrdup("/tmp/ssh-XXXXXXXXXX"); 200 201 /* Create private directory for socket */ 202 if (mkdtemp(auth_sock_dir) == NULL) { 203 ssh_packet_send_debug(ssh, "Agent forwarding disabled: " 204 "mkdtemp() failed: %.100s", strerror(errno)); 205 restore_uid(); 206 free(auth_sock_dir); 207 auth_sock_dir = NULL; 208 goto authsock_err; 209 } 210 211 xasprintf(&auth_sock_name, "%s/agent.%ld", 212 auth_sock_dir, (long) getpid()); 213 214 /* Start a Unix listener on auth_sock_name. */ 215 sock = unix_listener(auth_sock_name, SSH_LISTEN_BACKLOG, 0); 216 217 /* Restore the privileged uid. */ 218 restore_uid(); 219 220 /* Check for socket/bind/listen failure. */ 221 if (sock < 0) 222 goto authsock_err; 223 224 /* Allocate a channel for the authentication agent socket. */ 225 nc = channel_new(ssh, "auth socket", 226 SSH_CHANNEL_AUTH_SOCKET, sock, sock, -1, 227 CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 228 0, "auth socket", 1); 229 nc->path = xstrdup(auth_sock_name); 230 return 1; 231 232 authsock_err: 233 free(auth_sock_name); 234 if (auth_sock_dir != NULL) { 235 temporarily_use_uid(pw); 236 rmdir(auth_sock_dir); 237 restore_uid(); 238 free(auth_sock_dir); 239 } 240 if (sock != -1) 241 close(sock); 242 auth_sock_name = NULL; 243 auth_sock_dir = NULL; 244 return 0; 245 } 246 247 static void 248 display_loginmsg(void) 249 { 250 int r; 251 252 if (sshbuf_len(loginmsg) == 0) 253 return; 254 if ((r = sshbuf_put_u8(loginmsg, 0)) != 0) 255 fatal_fr(r, "sshbuf_put_u8"); 256 printf("%s", (char *)sshbuf_ptr(loginmsg)); 257 sshbuf_reset(loginmsg); 258 } 259 260 static void 261 prepare_auth_info_file(struct passwd *pw, struct sshbuf *info) 262 { 263 int fd = -1, success = 0; 264 265 if (!options.expose_userauth_info || info == NULL) 266 return; 267 268 temporarily_use_uid(pw); 269 auth_info_file = xstrdup("/tmp/sshauth.XXXXXXXXXXXXXXX"); 270 if ((fd = mkstemp(auth_info_file)) == -1) { 271 error_f("mkstemp: %s", strerror(errno)); 272 goto out; 273 } 274 if (atomicio(vwrite, fd, sshbuf_mutable_ptr(info), 275 sshbuf_len(info)) != sshbuf_len(info)) { 276 error_f("write: %s", strerror(errno)); 277 goto out; 278 } 279 if (close(fd) != 0) { 280 error_f("close: %s", strerror(errno)); 281 goto out; 282 } 283 success = 1; 284 out: 285 if (!success) { 286 if (fd != -1) 287 close(fd); 288 free(auth_info_file); 289 auth_info_file = NULL; 290 } 291 restore_uid(); 292 } 293 294 static void 295 set_fwdpermit_from_authopts(struct ssh *ssh, const struct sshauthopt *opts) 296 { 297 char *tmp, *cp, *host; 298 int port; 299 size_t i; 300 301 if ((options.allow_tcp_forwarding & FORWARD_LOCAL) != 0) { 302 channel_clear_permission(ssh, FORWARD_USER, FORWARD_LOCAL); 303 for (i = 0; i < auth_opts->npermitopen; i++) { 304 tmp = cp = xstrdup(auth_opts->permitopen[i]); 305 /* This shouldn't fail as it has already been checked */ 306 if ((host = hpdelim2(&cp, NULL)) == NULL) 307 fatal_f("internal error: hpdelim"); 308 host = cleanhostname(host); 309 if (cp == NULL || (port = permitopen_port(cp)) < 0) 310 fatal_f("internal error: permitopen port"); 311 channel_add_permission(ssh, 312 FORWARD_USER, FORWARD_LOCAL, host, port); 313 free(tmp); 314 } 315 } 316 if ((options.allow_tcp_forwarding & FORWARD_REMOTE) != 0) { 317 channel_clear_permission(ssh, FORWARD_USER, FORWARD_REMOTE); 318 for (i = 0; i < auth_opts->npermitlisten; i++) { 319 tmp = cp = xstrdup(auth_opts->permitlisten[i]); 320 /* This shouldn't fail as it has already been checked */ 321 if ((host = hpdelim(&cp)) == NULL) 322 fatal_f("internal error: hpdelim"); 323 host = cleanhostname(host); 324 if (cp == NULL || (port = permitopen_port(cp)) < 0) 325 fatal_f("internal error: permitlisten port"); 326 channel_add_permission(ssh, 327 FORWARD_USER, FORWARD_REMOTE, host, port); 328 free(tmp); 329 } 330 } 331 } 332 333 void 334 do_authenticated(struct ssh *ssh, Authctxt *authctxt) 335 { 336 setproctitle("%s", authctxt->pw->pw_name); 337 338 auth_log_authopts("active", auth_opts, 0); 339 340 /* setup the channel layer */ 341 /* XXX - streamlocal? */ 342 set_fwdpermit_from_authopts(ssh, auth_opts); 343 344 if (!auth_opts->permit_port_forwarding_flag || 345 options.disable_forwarding) { 346 channel_disable_admin(ssh, FORWARD_LOCAL); 347 channel_disable_admin(ssh, FORWARD_REMOTE); 348 } else { 349 if ((options.allow_tcp_forwarding & FORWARD_LOCAL) == 0) 350 channel_disable_admin(ssh, FORWARD_LOCAL); 351 else 352 channel_permit_all(ssh, FORWARD_LOCAL); 353 if ((options.allow_tcp_forwarding & FORWARD_REMOTE) == 0) 354 channel_disable_admin(ssh, FORWARD_REMOTE); 355 else 356 channel_permit_all(ssh, FORWARD_REMOTE); 357 } 358 auth_debug_send(ssh); 359 360 prepare_auth_info_file(authctxt->pw, authctxt->session_info); 361 362 do_authenticated2(ssh, authctxt); 363 364 do_cleanup(ssh, authctxt); 365 } 366 367 /* Check untrusted xauth strings for metacharacters */ 368 static int 369 xauth_valid_string(const char *s) 370 { 371 size_t i; 372 373 for (i = 0; s[i] != '\0'; i++) { 374 if (!isalnum((u_char)s[i]) && 375 s[i] != '.' && s[i] != ':' && s[i] != '/' && 376 s[i] != '-' && s[i] != '_') 377 return 0; 378 } 379 return 1; 380 } 381 382 #define USE_PIPES 1 383 /* 384 * This is called to fork and execute a command when we have no tty. This 385 * will call do_child from the child, and server_loop from the parent after 386 * setting up file descriptors and such. 387 */ 388 int 389 do_exec_no_pty(struct ssh *ssh, Session *s, const char *command) 390 { 391 pid_t pid; 392 #ifdef USE_PIPES 393 int pin[2], pout[2], perr[2]; 394 395 if (s == NULL) 396 fatal("do_exec_no_pty: no session"); 397 398 /* Allocate pipes for communicating with the program. */ 399 if (pipe(pin) == -1) { 400 error_f("pipe in: %.100s", strerror(errno)); 401 return -1; 402 } 403 if (pipe(pout) == -1) { 404 error_f("pipe out: %.100s", strerror(errno)); 405 close(pin[0]); 406 close(pin[1]); 407 return -1; 408 } 409 if (pipe(perr) == -1) { 410 error_f("pipe err: %.100s", strerror(errno)); 411 close(pin[0]); 412 close(pin[1]); 413 close(pout[0]); 414 close(pout[1]); 415 return -1; 416 } 417 #else 418 int inout[2], err[2]; 419 420 if (s == NULL) 421 fatal("do_exec_no_pty: no session"); 422 423 /* Uses socket pairs to communicate with the program. */ 424 if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) == -1) { 425 error_f("socketpair #1: %.100s", strerror(errno)); 426 return -1; 427 } 428 if (socketpair(AF_UNIX, SOCK_STREAM, 0, err) == -1) { 429 error_f("socketpair #2: %.100s", strerror(errno)); 430 close(inout[0]); 431 close(inout[1]); 432 return -1; 433 } 434 #endif 435 436 session_proctitle(s); 437 438 /* Fork the child. */ 439 switch ((pid = fork())) { 440 case -1: 441 error_f("fork: %.100s", strerror(errno)); 442 #ifdef USE_PIPES 443 close(pin[0]); 444 close(pin[1]); 445 close(pout[0]); 446 close(pout[1]); 447 close(perr[0]); 448 close(perr[1]); 449 #else 450 close(inout[0]); 451 close(inout[1]); 452 close(err[0]); 453 close(err[1]); 454 #endif 455 return -1; 456 case 0: 457 is_child = 1; 458 459 /* 460 * Create a new session and process group since the 4.4BSD 461 * setlogin() affects the entire process group. 462 */ 463 if (setsid() == -1) 464 error("setsid failed: %.100s", strerror(errno)); 465 466 #ifdef USE_PIPES 467 /* 468 * Redirect stdin. We close the parent side of the socket 469 * pair, and make the child side the standard input. 470 */ 471 close(pin[1]); 472 if (dup2(pin[0], 0) == -1) 473 perror("dup2 stdin"); 474 close(pin[0]); 475 476 /* Redirect stdout. */ 477 close(pout[0]); 478 if (dup2(pout[1], 1) == -1) 479 perror("dup2 stdout"); 480 close(pout[1]); 481 482 /* Redirect stderr. */ 483 close(perr[0]); 484 if (dup2(perr[1], 2) == -1) 485 perror("dup2 stderr"); 486 close(perr[1]); 487 #else 488 /* 489 * Redirect stdin, stdout, and stderr. Stdin and stdout will 490 * use the same socket, as some programs (particularly rdist) 491 * seem to depend on it. 492 */ 493 close(inout[1]); 494 close(err[1]); 495 if (dup2(inout[0], 0) == -1) /* stdin */ 496 perror("dup2 stdin"); 497 if (dup2(inout[0], 1) == -1) /* stdout (same as stdin) */ 498 perror("dup2 stdout"); 499 close(inout[0]); 500 if (dup2(err[0], 2) == -1) /* stderr */ 501 perror("dup2 stderr"); 502 close(err[0]); 503 #endif 504 505 /* Do processing for the child (exec command etc). */ 506 do_child(ssh, s, command); 507 /* NOTREACHED */ 508 default: 509 break; 510 } 511 512 #ifdef HAVE_CYGWIN 513 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); 514 #endif 515 516 s->pid = pid; 517 /* Set interactive/non-interactive mode. */ 518 ssh_packet_set_interactive(ssh, s->display != NULL, 519 options.ip_qos_interactive, options.ip_qos_bulk); 520 521 /* 522 * Clear loginmsg, since it's the child's responsibility to display 523 * it to the user, otherwise multiple sessions may accumulate 524 * multiple copies of the login messages. 525 */ 526 sshbuf_reset(loginmsg); 527 528 #ifdef USE_PIPES 529 /* We are the parent. Close the child sides of the pipes. */ 530 close(pin[0]); 531 close(pout[1]); 532 close(perr[1]); 533 534 session_set_fds(ssh, s, pin[1], pout[0], perr[0], 535 s->is_subsystem, 0); 536 #else 537 /* We are the parent. Close the child sides of the socket pairs. */ 538 close(inout[0]); 539 close(err[0]); 540 541 /* 542 * Enter the interactive session. Note: server_loop must be able to 543 * handle the case that fdin and fdout are the same. 544 */ 545 session_set_fds(ssh, s, inout[1], inout[1], err[1], 546 s->is_subsystem, 0); 547 #endif 548 return 0; 549 } 550 551 /* 552 * This is called to fork and execute a command when we have a tty. This 553 * will call do_child from the child, and server_loop from the parent after 554 * setting up file descriptors, controlling tty, updating wtmp, utmp, 555 * lastlog, and other such operations. 556 */ 557 int 558 do_exec_pty(struct ssh *ssh, Session *s, const char *command) 559 { 560 int fdout, ptyfd, ttyfd, ptymaster; 561 pid_t pid; 562 563 if (s == NULL) 564 fatal("do_exec_pty: no session"); 565 ptyfd = s->ptyfd; 566 ttyfd = s->ttyfd; 567 568 /* 569 * Create another descriptor of the pty master side for use as the 570 * standard input. We could use the original descriptor, but this 571 * simplifies code in server_loop. The descriptor is bidirectional. 572 * Do this before forking (and cleanup in the child) so as to 573 * detect and gracefully fail out-of-fd conditions. 574 */ 575 if ((fdout = dup(ptyfd)) == -1) { 576 error_f("dup #1: %s", strerror(errno)); 577 close(ttyfd); 578 close(ptyfd); 579 return -1; 580 } 581 /* we keep a reference to the pty master */ 582 if ((ptymaster = dup(ptyfd)) == -1) { 583 error_f("dup #2: %s", strerror(errno)); 584 close(ttyfd); 585 close(ptyfd); 586 close(fdout); 587 return -1; 588 } 589 590 /* Fork the child. */ 591 switch ((pid = fork())) { 592 case -1: 593 error_f("fork: %.100s", strerror(errno)); 594 close(fdout); 595 close(ptymaster); 596 close(ttyfd); 597 close(ptyfd); 598 return -1; 599 case 0: 600 is_child = 1; 601 602 close(fdout); 603 close(ptymaster); 604 605 /* Close the master side of the pseudo tty. */ 606 close(ptyfd); 607 608 /* Make the pseudo tty our controlling tty. */ 609 pty_make_controlling_tty(&ttyfd, s->tty); 610 611 /* Redirect stdin/stdout/stderr from the pseudo tty. */ 612 if (dup2(ttyfd, 0) == -1) 613 error("dup2 stdin: %s", strerror(errno)); 614 if (dup2(ttyfd, 1) == -1) 615 error("dup2 stdout: %s", strerror(errno)); 616 if (dup2(ttyfd, 2) == -1) 617 error("dup2 stderr: %s", strerror(errno)); 618 619 /* Close the extra descriptor for the pseudo tty. */ 620 close(ttyfd); 621 622 /* record login, etc. similar to login(1) */ 623 #ifndef HAVE_OSF_SIA 624 do_login(ssh, s, command); 625 #endif 626 /* 627 * Do common processing for the child, such as execing 628 * the command. 629 */ 630 do_child(ssh, s, command); 631 /* NOTREACHED */ 632 default: 633 break; 634 } 635 636 #ifdef HAVE_CYGWIN 637 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); 638 #endif 639 640 s->pid = pid; 641 642 /* Parent. Close the slave side of the pseudo tty. */ 643 close(ttyfd); 644 645 /* Enter interactive session. */ 646 s->ptymaster = ptymaster; 647 ssh_packet_set_interactive(ssh, 1, 648 options.ip_qos_interactive, options.ip_qos_bulk); 649 session_set_fds(ssh, s, ptyfd, fdout, -1, 1, 1); 650 return 0; 651 } 652 653 /* 654 * This is called to fork and execute a command. If another command is 655 * to be forced, execute that instead. 656 */ 657 int 658 do_exec(struct ssh *ssh, Session *s, const char *command) 659 { 660 int ret; 661 const char *forced = NULL, *tty = NULL; 662 char session_type[1024]; 663 664 if (options.adm_forced_command) { 665 original_command = command; 666 command = options.adm_forced_command; 667 forced = "(config)"; 668 } else if (auth_opts->force_command != NULL) { 669 original_command = command; 670 command = auth_opts->force_command; 671 forced = "(key-option)"; 672 } 673 s->forced = 0; 674 if (forced != NULL) { 675 s->forced = 1; 676 if (IS_INTERNAL_SFTP(command)) { 677 s->is_subsystem = s->is_subsystem ? 678 SUBSYSTEM_INT_SFTP : SUBSYSTEM_INT_SFTP_ERROR; 679 } else if (s->is_subsystem) 680 s->is_subsystem = SUBSYSTEM_EXT; 681 snprintf(session_type, sizeof(session_type), 682 "forced-command %s '%.900s'", forced, command); 683 } else if (s->is_subsystem) { 684 snprintf(session_type, sizeof(session_type), 685 "subsystem '%.900s'", s->subsys); 686 } else if (command == NULL) { 687 snprintf(session_type, sizeof(session_type), "shell"); 688 } else { 689 /* NB. we don't log unforced commands to preserve privacy */ 690 snprintf(session_type, sizeof(session_type), "command"); 691 } 692 693 if (s->ttyfd != -1) { 694 tty = s->tty; 695 if (strncmp(tty, "/dev/", 5) == 0) 696 tty += 5; 697 } 698 699 verbose("Starting session: %s%s%s for %s from %.200s port %d id %d", 700 session_type, 701 tty == NULL ? "" : " on ", 702 tty == NULL ? "" : tty, 703 s->pw->pw_name, 704 ssh_remote_ipaddr(ssh), 705 ssh_remote_port(ssh), 706 s->self); 707 708 #ifdef SSH_AUDIT_EVENTS 709 if (command != NULL) 710 PRIVSEP(audit_run_command(command)); 711 else if (s->ttyfd == -1) { 712 char *shell = s->pw->pw_shell; 713 714 if (shell[0] == '\0') /* empty shell means /bin/sh */ 715 shell =_PATH_BSHELL; 716 PRIVSEP(audit_run_command(shell)); 717 } 718 #endif 719 if (s->ttyfd != -1) 720 ret = do_exec_pty(ssh, s, command); 721 else 722 ret = do_exec_no_pty(ssh, s, command); 723 724 original_command = NULL; 725 726 /* 727 * Clear loginmsg: it's the child's responsibility to display 728 * it to the user, otherwise multiple sessions may accumulate 729 * multiple copies of the login messages. 730 */ 731 sshbuf_reset(loginmsg); 732 733 return ret; 734 } 735 736 /* administrative, login(1)-like work */ 737 void 738 do_login(struct ssh *ssh, Session *s, const char *command) 739 { 740 socklen_t fromlen; 741 struct sockaddr_storage from; 742 struct passwd * pw = s->pw; 743 pid_t pid = getpid(); 744 745 /* 746 * Get IP address of client. If the connection is not a socket, let 747 * the address be 0.0.0.0. 748 */ 749 memset(&from, 0, sizeof(from)); 750 fromlen = sizeof(from); 751 if (ssh_packet_connection_is_on_socket(ssh)) { 752 if (getpeername(ssh_packet_get_connection_in(ssh), 753 (struct sockaddr *)&from, &fromlen) == -1) { 754 debug("getpeername: %.100s", strerror(errno)); 755 cleanup_exit(255); 756 } 757 } 758 759 /* Record that there was a login on that tty from the remote host. */ 760 if (!use_privsep) 761 record_login(pid, s->tty, pw->pw_name, pw->pw_uid, 762 session_get_remote_name_or_ip(ssh, utmp_len, 763 options.use_dns), 764 (struct sockaddr *)&from, fromlen); 765 766 #ifdef USE_PAM 767 /* 768 * If password change is needed, do it now. 769 * This needs to occur before the ~/.hushlogin check. 770 */ 771 if (options.use_pam && !use_privsep && s->authctxt->force_pwchange) { 772 display_loginmsg(); 773 do_pam_chauthtok(); 774 s->authctxt->force_pwchange = 0; 775 /* XXX - signal [net] parent to enable forwardings */ 776 } 777 #endif 778 779 if (check_quietlogin(s, command)) 780 return; 781 782 display_loginmsg(); 783 784 do_motd(); 785 } 786 787 /* 788 * Display the message of the day. 789 */ 790 void 791 do_motd(void) 792 { 793 FILE *f; 794 char buf[256]; 795 796 if (options.print_motd) { 797 #ifdef HAVE_LOGIN_CAP 798 f = fopen(login_getcapstr(lc, "welcome", "/etc/motd", 799 "/etc/motd"), "r"); 800 #else 801 f = fopen("/etc/motd", "r"); 802 #endif 803 if (f) { 804 while (fgets(buf, sizeof(buf), f)) 805 fputs(buf, stdout); 806 fclose(f); 807 } 808 } 809 } 810 811 812 /* 813 * Check for quiet login, either .hushlogin or command given. 814 */ 815 int 816 check_quietlogin(Session *s, const char *command) 817 { 818 char buf[256]; 819 struct passwd *pw = s->pw; 820 struct stat st; 821 822 /* Return 1 if .hushlogin exists or a command given. */ 823 if (command != NULL) 824 return 1; 825 snprintf(buf, sizeof(buf), "%.200s/.hushlogin", pw->pw_dir); 826 #ifdef HAVE_LOGIN_CAP 827 if (login_getcapbool(lc, "hushlogin", 0) || stat(buf, &st) >= 0) 828 return 1; 829 #else 830 if (stat(buf, &st) >= 0) 831 return 1; 832 #endif 833 return 0; 834 } 835 836 /* 837 * Reads environment variables from the given file and adds/overrides them 838 * into the environment. If the file does not exist, this does nothing. 839 * Otherwise, it must consist of empty lines, comments (line starts with '#') 840 * and assignments of the form name=value. No other forms are allowed. 841 * If allowlist is not NULL, then it is interpreted as a pattern list and 842 * only variable names that match it will be accepted. 843 */ 844 static void 845 read_environment_file(char ***env, u_int *envsize, 846 const char *filename, const char *allowlist) 847 { 848 FILE *f; 849 char *line = NULL, *cp, *value; 850 size_t linesize = 0; 851 u_int lineno = 0; 852 853 f = fopen(filename, "r"); 854 if (!f) 855 return; 856 857 while (getline(&line, &linesize, f) != -1) { 858 if (++lineno > 1000) 859 fatal("Too many lines in environment file %s", filename); 860 for (cp = line; *cp == ' ' || *cp == '\t'; cp++) 861 ; 862 if (!*cp || *cp == '#' || *cp == '\n') 863 continue; 864 865 cp[strcspn(cp, "\n")] = '\0'; 866 867 value = strchr(cp, '='); 868 if (value == NULL) { 869 fprintf(stderr, "Bad line %u in %.100s\n", lineno, 870 filename); 871 continue; 872 } 873 /* 874 * Replace the equals sign by nul, and advance value to 875 * the value string. 876 */ 877 *value = '\0'; 878 value++; 879 if (allowlist != NULL && 880 match_pattern_list(cp, allowlist, 0) != 1) 881 continue; 882 child_set_env(env, envsize, cp, value); 883 } 884 free(line); 885 fclose(f); 886 } 887 888 #ifdef HAVE_ETC_DEFAULT_LOGIN 889 /* 890 * Return named variable from specified environment, or NULL if not present. 891 */ 892 static char * 893 child_get_env(char **env, const char *name) 894 { 895 int i; 896 size_t len; 897 898 len = strlen(name); 899 for (i=0; env[i] != NULL; i++) 900 if (strncmp(name, env[i], len) == 0 && env[i][len] == '=') 901 return(env[i] + len + 1); 902 return NULL; 903 } 904 905 /* 906 * Read /etc/default/login. 907 * We pick up the PATH (or SUPATH for root) and UMASK. 908 */ 909 static void 910 read_etc_default_login(char ***env, u_int *envsize, uid_t uid) 911 { 912 char **tmpenv = NULL, *var; 913 u_int i, tmpenvsize = 0; 914 u_long mask; 915 916 /* 917 * We don't want to copy the whole file to the child's environment, 918 * so we use a temporary environment and copy the variables we're 919 * interested in. 920 */ 921 read_environment_file(&tmpenv, &tmpenvsize, "/etc/default/login", 922 options.permit_user_env_allowlist); 923 924 if (tmpenv == NULL) 925 return; 926 927 if (uid == 0) 928 var = child_get_env(tmpenv, "SUPATH"); 929 else 930 var = child_get_env(tmpenv, "PATH"); 931 if (var != NULL) 932 child_set_env(env, envsize, "PATH", var); 933 934 if ((var = child_get_env(tmpenv, "UMASK")) != NULL) 935 if (sscanf(var, "%5lo", &mask) == 1) 936 umask((mode_t)mask); 937 938 for (i = 0; tmpenv[i] != NULL; i++) 939 free(tmpenv[i]); 940 free(tmpenv); 941 } 942 #endif /* HAVE_ETC_DEFAULT_LOGIN */ 943 944 #if defined(USE_PAM) || defined(HAVE_CYGWIN) 945 static void 946 copy_environment_denylist(char **source, char ***env, u_int *envsize, 947 const char *denylist) 948 { 949 char *var_name, *var_val; 950 int i; 951 952 if (source == NULL) 953 return; 954 955 for(i = 0; source[i] != NULL; i++) { 956 var_name = xstrdup(source[i]); 957 if ((var_val = strstr(var_name, "=")) == NULL) { 958 free(var_name); 959 continue; 960 } 961 *var_val++ = '\0'; 962 963 if (denylist == NULL || 964 match_pattern_list(var_name, denylist, 0) != 1) { 965 debug3("Copy environment: %s=%s", var_name, var_val); 966 child_set_env(env, envsize, var_name, var_val); 967 } 968 969 free(var_name); 970 } 971 } 972 #endif /* defined(USE_PAM) || defined(HAVE_CYGWIN) */ 973 974 #ifdef HAVE_CYGWIN 975 static void 976 copy_environment(char **source, char ***env, u_int *envsize) 977 { 978 copy_environment_denylist(source, env, envsize, NULL); 979 } 980 #endif 981 982 static char ** 983 do_setup_env(struct ssh *ssh, Session *s, const char *shell) 984 { 985 char buf[256]; 986 size_t n; 987 u_int i, envsize; 988 char *ocp, *cp, *value, **env, *laddr; 989 struct passwd *pw = s->pw; 990 #if !defined (HAVE_LOGIN_CAP) && !defined (HAVE_CYGWIN) 991 char *path = NULL; 992 #endif 993 994 /* Initialize the environment. */ 995 envsize = 100; 996 env = xcalloc(envsize, sizeof(char *)); 997 env[0] = NULL; 998 999 #ifdef HAVE_CYGWIN 1000 /* 1001 * The Windows environment contains some setting which are 1002 * important for a running system. They must not be dropped. 1003 */ 1004 { 1005 char **p; 1006 1007 p = fetch_windows_environment(); 1008 copy_environment(p, &env, &envsize); 1009 free_windows_environment(p); 1010 } 1011 #endif 1012 1013 #ifdef GSSAPI 1014 /* Allow any GSSAPI methods that we've used to alter 1015 * the child's environment as they see fit 1016 */ 1017 ssh_gssapi_do_child(&env, &envsize); 1018 #endif 1019 1020 /* Set basic environment. */ 1021 for (i = 0; i < s->num_env; i++) 1022 child_set_env(&env, &envsize, s->env[i].name, s->env[i].val); 1023 1024 child_set_env(&env, &envsize, "USER", pw->pw_name); 1025 child_set_env(&env, &envsize, "LOGNAME", pw->pw_name); 1026 #ifdef _AIX 1027 child_set_env(&env, &envsize, "LOGIN", pw->pw_name); 1028 #endif 1029 child_set_env(&env, &envsize, "HOME", pw->pw_dir); 1030 #ifdef HAVE_LOGIN_CAP 1031 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETPATH) < 0) 1032 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); 1033 else 1034 child_set_env(&env, &envsize, "PATH", getenv("PATH")); 1035 #else /* HAVE_LOGIN_CAP */ 1036 # ifndef HAVE_CYGWIN 1037 /* 1038 * There's no standard path on Windows. The path contains 1039 * important components pointing to the system directories, 1040 * needed for loading shared libraries. So the path better 1041 * remains intact here. 1042 */ 1043 # ifdef HAVE_ETC_DEFAULT_LOGIN 1044 read_etc_default_login(&env, &envsize, pw->pw_uid); 1045 path = child_get_env(env, "PATH"); 1046 # endif /* HAVE_ETC_DEFAULT_LOGIN */ 1047 if (path == NULL || *path == '\0') { 1048 child_set_env(&env, &envsize, "PATH", 1049 s->pw->pw_uid == 0 ? SUPERUSER_PATH : _PATH_STDPATH); 1050 } 1051 # endif /* HAVE_CYGWIN */ 1052 #endif /* HAVE_LOGIN_CAP */ 1053 1054 if (!options.use_pam) { 1055 snprintf(buf, sizeof buf, "%.200s/%.50s", 1056 _PATH_MAILDIR, pw->pw_name); 1057 child_set_env(&env, &envsize, "MAIL", buf); 1058 } 1059 1060 /* Normal systems set SHELL by default. */ 1061 child_set_env(&env, &envsize, "SHELL", shell); 1062 1063 if (getenv("TZ")) 1064 child_set_env(&env, &envsize, "TZ", getenv("TZ")); 1065 if (s->term) 1066 child_set_env(&env, &envsize, "TERM", s->term); 1067 if (s->display) 1068 child_set_env(&env, &envsize, "DISPLAY", s->display); 1069 1070 /* 1071 * Since we clear KRB5CCNAME at startup, if it's set now then it 1072 * must have been set by a native authentication method (eg AIX or 1073 * SIA), so copy it to the child. 1074 */ 1075 { 1076 char *cp; 1077 1078 if ((cp = getenv("KRB5CCNAME")) != NULL) 1079 child_set_env(&env, &envsize, "KRB5CCNAME", cp); 1080 } 1081 1082 #ifdef _AIX 1083 { 1084 char *cp; 1085 1086 if ((cp = getenv("AUTHSTATE")) != NULL) 1087 child_set_env(&env, &envsize, "AUTHSTATE", cp); 1088 read_environment_file(&env, &envsize, "/etc/environment", 1089 options.permit_user_env_allowlist); 1090 } 1091 #endif 1092 #ifdef KRB5 1093 if (s->authctxt->krb5_ccname) 1094 child_set_env(&env, &envsize, "KRB5CCNAME", 1095 s->authctxt->krb5_ccname); 1096 #endif 1097 if (auth_sock_name != NULL) 1098 child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME, 1099 auth_sock_name); 1100 1101 1102 /* Set custom environment options from pubkey authentication. */ 1103 if (options.permit_user_env) { 1104 for (n = 0 ; n < auth_opts->nenv; n++) { 1105 ocp = xstrdup(auth_opts->env[n]); 1106 cp = strchr(ocp, '='); 1107 if (cp != NULL) { 1108 *cp = '\0'; 1109 /* Apply PermitUserEnvironment allowlist */ 1110 if (options.permit_user_env_allowlist == NULL || 1111 match_pattern_list(ocp, 1112 options.permit_user_env_allowlist, 0) == 1) 1113 child_set_env(&env, &envsize, 1114 ocp, cp + 1); 1115 } 1116 free(ocp); 1117 } 1118 } 1119 1120 /* read $HOME/.ssh/environment. */ 1121 if (options.permit_user_env) { 1122 snprintf(buf, sizeof buf, "%.200s/%s/environment", 1123 pw->pw_dir, _PATH_SSH_USER_DIR); 1124 read_environment_file(&env, &envsize, buf, 1125 options.permit_user_env_allowlist); 1126 } 1127 1128 #ifdef USE_PAM 1129 /* 1130 * Pull in any environment variables that may have 1131 * been set by PAM. 1132 */ 1133 if (options.use_pam) { 1134 char **p; 1135 1136 /* 1137 * Don't allow PAM-internal env vars to leak 1138 * back into the session environment. 1139 */ 1140 #define PAM_ENV_DENYLIST "SSH_AUTH_INFO*,SSH_CONNECTION*" 1141 p = fetch_pam_child_environment(); 1142 copy_environment_denylist(p, &env, &envsize, 1143 PAM_ENV_DENYLIST); 1144 free_pam_environment(p); 1145 1146 p = fetch_pam_environment(); 1147 copy_environment_denylist(p, &env, &envsize, 1148 PAM_ENV_DENYLIST); 1149 free_pam_environment(p); 1150 } 1151 #endif /* USE_PAM */ 1152 1153 /* Environment specified by admin */ 1154 for (i = 0; i < options.num_setenv; i++) { 1155 cp = xstrdup(options.setenv[i]); 1156 if ((value = strchr(cp, '=')) == NULL) { 1157 /* shouldn't happen; vars are checked in servconf.c */ 1158 fatal("Invalid config SetEnv: %s", options.setenv[i]); 1159 } 1160 *value++ = '\0'; 1161 child_set_env(&env, &envsize, cp, value); 1162 } 1163 1164 /* SSH_CLIENT deprecated */ 1165 snprintf(buf, sizeof buf, "%.50s %d %d", 1166 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 1167 ssh_local_port(ssh)); 1168 child_set_env(&env, &envsize, "SSH_CLIENT", buf); 1169 1170 laddr = get_local_ipaddr(ssh_packet_get_connection_in(ssh)); 1171 snprintf(buf, sizeof buf, "%.50s %d %.50s %d", 1172 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 1173 laddr, ssh_local_port(ssh)); 1174 free(laddr); 1175 child_set_env(&env, &envsize, "SSH_CONNECTION", buf); 1176 1177 if (tun_fwd_ifnames != NULL) 1178 child_set_env(&env, &envsize, "SSH_TUNNEL", tun_fwd_ifnames); 1179 if (auth_info_file != NULL) 1180 child_set_env(&env, &envsize, "SSH_USER_AUTH", auth_info_file); 1181 if (s->ttyfd != -1) 1182 child_set_env(&env, &envsize, "SSH_TTY", s->tty); 1183 if (original_command) 1184 child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND", 1185 original_command); 1186 1187 if (debug_flag) { 1188 /* dump the environment */ 1189 fprintf(stderr, "Environment:\n"); 1190 for (i = 0; env[i]; i++) 1191 fprintf(stderr, " %.200s\n", env[i]); 1192 } 1193 return env; 1194 } 1195 1196 /* 1197 * Run $HOME/.ssh/rc, /etc/ssh/sshrc, or xauth (whichever is found 1198 * first in this order). 1199 */ 1200 static void 1201 do_rc_files(struct ssh *ssh, Session *s, const char *shell) 1202 { 1203 FILE *f = NULL; 1204 char *cmd = NULL, *user_rc = NULL; 1205 int do_xauth; 1206 struct stat st; 1207 1208 do_xauth = 1209 s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL; 1210 xasprintf(&user_rc, "%s/%s", s->pw->pw_dir, _PATH_SSH_USER_RC); 1211 1212 /* ignore _PATH_SSH_USER_RC for subsystems and admin forced commands */ 1213 if (!s->is_subsystem && options.adm_forced_command == NULL && 1214 auth_opts->permit_user_rc && options.permit_user_rc && 1215 stat(user_rc, &st) >= 0) { 1216 if (xasprintf(&cmd, "%s -c '%s %s'", shell, _PATH_BSHELL, 1217 user_rc) == -1) 1218 fatal_f("xasprintf: %s", strerror(errno)); 1219 if (debug_flag) 1220 fprintf(stderr, "Running %s\n", cmd); 1221 f = popen(cmd, "w"); 1222 if (f) { 1223 if (do_xauth) 1224 fprintf(f, "%s %s\n", s->auth_proto, 1225 s->auth_data); 1226 pclose(f); 1227 } else 1228 fprintf(stderr, "Could not run %s\n", 1229 user_rc); 1230 } else if (stat(_PATH_SSH_SYSTEM_RC, &st) >= 0) { 1231 if (debug_flag) 1232 fprintf(stderr, "Running %s %s\n", _PATH_BSHELL, 1233 _PATH_SSH_SYSTEM_RC); 1234 f = popen(_PATH_BSHELL " " _PATH_SSH_SYSTEM_RC, "w"); 1235 if (f) { 1236 if (do_xauth) 1237 fprintf(f, "%s %s\n", s->auth_proto, 1238 s->auth_data); 1239 pclose(f); 1240 } else 1241 fprintf(stderr, "Could not run %s\n", 1242 _PATH_SSH_SYSTEM_RC); 1243 } else if (do_xauth && options.xauth_location != NULL) { 1244 /* Add authority data to .Xauthority if appropriate. */ 1245 if (debug_flag) { 1246 fprintf(stderr, 1247 "Running %.500s remove %.100s\n", 1248 options.xauth_location, s->auth_display); 1249 fprintf(stderr, 1250 "%.500s add %.100s %.100s %.100s\n", 1251 options.xauth_location, s->auth_display, 1252 s->auth_proto, s->auth_data); 1253 } 1254 if (xasprintf(&cmd, "%s -q -", options.xauth_location) == -1) 1255 fatal_f("xasprintf: %s", strerror(errno)); 1256 f = popen(cmd, "w"); 1257 if (f) { 1258 fprintf(f, "remove %s\n", 1259 s->auth_display); 1260 fprintf(f, "add %s %s %s\n", 1261 s->auth_display, s->auth_proto, 1262 s->auth_data); 1263 pclose(f); 1264 } else { 1265 fprintf(stderr, "Could not run %s\n", 1266 cmd); 1267 } 1268 } 1269 free(cmd); 1270 free(user_rc); 1271 } 1272 1273 static void 1274 do_nologin(struct passwd *pw) 1275 { 1276 FILE *f = NULL; 1277 char buf[1024], *nl, *def_nl = _PATH_NOLOGIN; 1278 struct stat sb; 1279 1280 #ifdef HAVE_LOGIN_CAP 1281 if (login_getcapbool(lc, "ignorenologin", 0) || pw->pw_uid == 0) 1282 return; 1283 nl = strdup(login_getcapstr(lc, "nologin", def_nl, def_nl)); 1284 #else 1285 if (pw->pw_uid == 0) 1286 return; 1287 nl = def_nl; 1288 #endif 1289 if (stat(nl, &sb) == -1) 1290 return; 1291 1292 /* /etc/nologin exists. Print its contents if we can and exit. */ 1293 logit("User %.100s not allowed because %s exists", pw->pw_name, nl); 1294 if ((f = fopen(nl, "r")) != NULL) { 1295 while (fgets(buf, sizeof(buf), f)) 1296 fputs(buf, stderr); 1297 fclose(f); 1298 } 1299 exit(254); 1300 } 1301 1302 /* 1303 * Chroot into a directory after checking it for safety: all path components 1304 * must be root-owned directories with strict permissions. 1305 */ 1306 static void 1307 safely_chroot(const char *path, uid_t uid) 1308 { 1309 const char *cp; 1310 char component[PATH_MAX]; 1311 struct stat st; 1312 1313 if (!path_absolute(path)) 1314 fatal("chroot path does not begin at root"); 1315 if (strlen(path) >= sizeof(component)) 1316 fatal("chroot path too long"); 1317 1318 /* 1319 * Descend the path, checking that each component is a 1320 * root-owned directory with strict permissions. 1321 */ 1322 for (cp = path; cp != NULL;) { 1323 if ((cp = strchr(cp, '/')) == NULL) 1324 strlcpy(component, path, sizeof(component)); 1325 else { 1326 cp++; 1327 memcpy(component, path, cp - path); 1328 component[cp - path] = '\0'; 1329 } 1330 1331 debug3_f("checking '%s'", component); 1332 1333 if (stat(component, &st) != 0) 1334 fatal_f("stat(\"%s\"): %s", 1335 component, strerror(errno)); 1336 if (st.st_uid != 0 || (st.st_mode & 022) != 0) 1337 fatal("bad ownership or modes for chroot " 1338 "directory %s\"%s\"", 1339 cp == NULL ? "" : "component ", component); 1340 if (!S_ISDIR(st.st_mode)) 1341 fatal("chroot path %s\"%s\" is not a directory", 1342 cp == NULL ? "" : "component ", component); 1343 1344 } 1345 1346 if (chdir(path) == -1) 1347 fatal("Unable to chdir to chroot path \"%s\": " 1348 "%s", path, strerror(errno)); 1349 if (chroot(path) == -1) 1350 fatal("chroot(\"%s\"): %s", path, strerror(errno)); 1351 if (chdir("/") == -1) 1352 fatal_f("chdir(/) after chroot: %s", strerror(errno)); 1353 verbose("Changed root directory to \"%s\"", path); 1354 } 1355 1356 /* Set login name, uid, gid, and groups. */ 1357 void 1358 do_setusercontext(struct passwd *pw) 1359 { 1360 char uidstr[32], *chroot_path, *tmp; 1361 1362 platform_setusercontext(pw); 1363 1364 if (platform_privileged_uidswap()) { 1365 #ifdef HAVE_LOGIN_CAP 1366 if (setusercontext(lc, pw, pw->pw_uid, 1367 (LOGIN_SETALL & ~(LOGIN_SETPATH|LOGIN_SETUSER))) < 0) { 1368 perror("unable to set user context"); 1369 exit(1); 1370 } 1371 #else 1372 if (setlogin(pw->pw_name) < 0) 1373 error("setlogin failed: %s", strerror(errno)); 1374 if (setgid(pw->pw_gid) < 0) { 1375 perror("setgid"); 1376 exit(1); 1377 } 1378 /* Initialize the group list. */ 1379 if (initgroups(pw->pw_name, pw->pw_gid) < 0) { 1380 perror("initgroups"); 1381 exit(1); 1382 } 1383 endgrent(); 1384 #endif 1385 1386 platform_setusercontext_post_groups(pw); 1387 1388 if (!in_chroot && options.chroot_directory != NULL && 1389 strcasecmp(options.chroot_directory, "none") != 0) { 1390 tmp = tilde_expand_filename(options.chroot_directory, 1391 pw->pw_uid); 1392 snprintf(uidstr, sizeof(uidstr), "%llu", 1393 (unsigned long long)pw->pw_uid); 1394 chroot_path = percent_expand(tmp, "h", pw->pw_dir, 1395 "u", pw->pw_name, "U", uidstr, (char *)NULL); 1396 safely_chroot(chroot_path, pw->pw_uid); 1397 free(tmp); 1398 free(chroot_path); 1399 /* Make sure we don't attempt to chroot again */ 1400 free(options.chroot_directory); 1401 options.chroot_directory = NULL; 1402 in_chroot = 1; 1403 } 1404 1405 #ifdef HAVE_LOGIN_CAP 1406 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUSER) < 0) { 1407 perror("unable to set user context (setuser)"); 1408 exit(1); 1409 } 1410 /* 1411 * FreeBSD's setusercontext() will not apply the user's 1412 * own umask setting unless running with the user's UID. 1413 */ 1414 (void) setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUMASK); 1415 #else 1416 # ifdef USE_LIBIAF 1417 /* 1418 * In a chroot environment, the set_id() will always fail; 1419 * typically because of the lack of necessary authentication 1420 * services and runtime such as ./usr/lib/libiaf.so, 1421 * ./usr/lib/libpam.so.1, and ./etc/passwd We skip it in the 1422 * internal sftp chroot case. We'll lose auditing and ACLs but 1423 * permanently_set_uid will take care of the rest. 1424 */ 1425 if (!in_chroot && set_id(pw->pw_name) != 0) 1426 fatal("set_id(%s) Failed", pw->pw_name); 1427 # endif /* USE_LIBIAF */ 1428 /* Permanently switch to the desired uid. */ 1429 permanently_set_uid(pw); 1430 #endif 1431 } else if (options.chroot_directory != NULL && 1432 strcasecmp(options.chroot_directory, "none") != 0) { 1433 fatal("server lacks privileges to chroot to ChrootDirectory"); 1434 } 1435 1436 if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) 1437 fatal("Failed to set uids to %u.", (u_int) pw->pw_uid); 1438 } 1439 1440 static void 1441 do_pwchange(Session *s) 1442 { 1443 fflush(NULL); 1444 fprintf(stderr, "WARNING: Your password has expired.\n"); 1445 if (s->ttyfd != -1) { 1446 fprintf(stderr, 1447 "You must change your password now and login again!\n"); 1448 #ifdef WITH_SELINUX 1449 setexeccon(NULL); 1450 #endif 1451 #ifdef PASSWD_NEEDS_USERNAME 1452 execl(_PATH_PASSWD_PROG, "passwd", s->pw->pw_name, 1453 (char *)NULL); 1454 #else 1455 execl(_PATH_PASSWD_PROG, "passwd", (char *)NULL); 1456 #endif 1457 perror("passwd"); 1458 } else { 1459 fprintf(stderr, 1460 "Password change required but no TTY available.\n"); 1461 } 1462 exit(1); 1463 } 1464 1465 static void 1466 child_close_fds(struct ssh *ssh) 1467 { 1468 extern int auth_sock; 1469 1470 if (auth_sock != -1) { 1471 close(auth_sock); 1472 auth_sock = -1; 1473 } 1474 1475 if (ssh_packet_get_connection_in(ssh) == 1476 ssh_packet_get_connection_out(ssh)) 1477 close(ssh_packet_get_connection_in(ssh)); 1478 else { 1479 close(ssh_packet_get_connection_in(ssh)); 1480 close(ssh_packet_get_connection_out(ssh)); 1481 } 1482 /* 1483 * Close all descriptors related to channels. They will still remain 1484 * open in the parent. 1485 */ 1486 /* XXX better use close-on-exec? -markus */ 1487 channel_close_all(ssh); 1488 1489 /* 1490 * Close any extra file descriptors. Note that there may still be 1491 * descriptors left by system functions. They will be closed later. 1492 */ 1493 endpwent(); 1494 1495 /* Stop directing logs to a high-numbered fd before we close it */ 1496 log_redirect_stderr_to(NULL); 1497 1498 /* 1499 * Close any extra open file descriptors so that we don't have them 1500 * hanging around in clients. Note that we want to do this after 1501 * initgroups, because at least on Solaris 2.3 it leaves file 1502 * descriptors open. 1503 */ 1504 closefrom(STDERR_FILENO + 1); 1505 } 1506 1507 /* 1508 * Performs common processing for the child, such as setting up the 1509 * environment, closing extra file descriptors, setting the user and group 1510 * ids, and executing the command or shell. 1511 */ 1512 #define ARGV_MAX 10 1513 void 1514 do_child(struct ssh *ssh, Session *s, const char *command) 1515 { 1516 extern char **environ; 1517 char **env, *argv[ARGV_MAX], remote_id[512]; 1518 const char *shell, *shell0; 1519 struct passwd *pw = s->pw; 1520 int r = 0; 1521 1522 sshpkt_fmt_connection_id(ssh, remote_id, sizeof(remote_id)); 1523 1524 /* remove hostkey from the child's memory */ 1525 destroy_sensitive_data(); 1526 ssh_packet_clear_keys(ssh); 1527 1528 /* Force a password change */ 1529 if (s->authctxt->force_pwchange) { 1530 do_setusercontext(pw); 1531 child_close_fds(ssh); 1532 do_pwchange(s); 1533 exit(1); 1534 } 1535 1536 /* 1537 * Login(1) does this as well, and it needs uid 0 for the "-h" 1538 * switch, so we let login(1) to this for us. 1539 */ 1540 #ifdef HAVE_OSF_SIA 1541 session_setup_sia(pw, s->ttyfd == -1 ? NULL : s->tty); 1542 if (!check_quietlogin(s, command)) 1543 do_motd(); 1544 #else /* HAVE_OSF_SIA */ 1545 /* When PAM is enabled we rely on it to do the nologin check */ 1546 if (!options.use_pam) 1547 do_nologin(pw); 1548 do_setusercontext(pw); 1549 /* 1550 * PAM session modules in do_setusercontext may have 1551 * generated messages, so if this in an interactive 1552 * login then display them too. 1553 */ 1554 if (!check_quietlogin(s, command)) 1555 display_loginmsg(); 1556 #endif /* HAVE_OSF_SIA */ 1557 1558 #ifdef USE_PAM 1559 if (options.use_pam && !is_pam_session_open()) { 1560 debug3("PAM session not opened, exiting"); 1561 display_loginmsg(); 1562 exit(254); 1563 } 1564 #endif 1565 1566 /* 1567 * Get the shell from the password data. An empty shell field is 1568 * legal, and means /bin/sh. 1569 */ 1570 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; 1571 1572 /* 1573 * Make sure $SHELL points to the shell from the password file, 1574 * even if shell is overridden from login.conf 1575 */ 1576 env = do_setup_env(ssh, s, shell); 1577 1578 #ifdef HAVE_LOGIN_CAP 1579 shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell); 1580 #endif 1581 1582 /* 1583 * Close the connection descriptors; note that this is the child, and 1584 * the server will still have the socket open, and it is important 1585 * that we do not shutdown it. Note that the descriptors cannot be 1586 * closed before building the environment, as we call 1587 * ssh_remote_ipaddr there. 1588 */ 1589 child_close_fds(ssh); 1590 1591 /* 1592 * Must take new environment into use so that .ssh/rc, 1593 * /etc/ssh/sshrc and xauth are run in the proper environment. 1594 */ 1595 environ = env; 1596 1597 #if defined(KRB5) && defined(USE_AFS) 1598 /* 1599 * At this point, we check to see if AFS is active and if we have 1600 * a valid Kerberos 5 TGT. If so, it seems like a good idea to see 1601 * if we can (and need to) extend the ticket into an AFS token. If 1602 * we don't do this, we run into potential problems if the user's 1603 * home directory is in AFS and it's not world-readable. 1604 */ 1605 1606 if (options.kerberos_get_afs_token && k_hasafs() && 1607 (s->authctxt->krb5_ctx != NULL)) { 1608 char cell[64]; 1609 1610 debug("Getting AFS token"); 1611 1612 k_setpag(); 1613 1614 if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0) 1615 krb5_afslog(s->authctxt->krb5_ctx, 1616 s->authctxt->krb5_fwd_ccache, cell, NULL); 1617 1618 krb5_afslog_home(s->authctxt->krb5_ctx, 1619 s->authctxt->krb5_fwd_ccache, NULL, NULL, pw->pw_dir); 1620 } 1621 #endif 1622 1623 /* Change current directory to the user's home directory. */ 1624 if (chdir(pw->pw_dir) == -1) { 1625 /* Suppress missing homedir warning for chroot case */ 1626 #ifdef HAVE_LOGIN_CAP 1627 r = login_getcapbool(lc, "requirehome", 0); 1628 #endif 1629 if (r || !in_chroot) { 1630 fprintf(stderr, "Could not chdir to home " 1631 "directory %s: %s\n", pw->pw_dir, 1632 strerror(errno)); 1633 } 1634 if (r) 1635 exit(1); 1636 } 1637 1638 closefrom(STDERR_FILENO + 1); 1639 1640 do_rc_files(ssh, s, shell); 1641 1642 /* restore SIGPIPE for child */ 1643 ssh_signal(SIGPIPE, SIG_DFL); 1644 1645 if (s->is_subsystem == SUBSYSTEM_INT_SFTP_ERROR) { 1646 error("Connection from %s: refusing non-sftp session", 1647 remote_id); 1648 printf("This service allows sftp connections only.\n"); 1649 fflush(NULL); 1650 exit(1); 1651 } else if (s->is_subsystem == SUBSYSTEM_INT_SFTP) { 1652 extern int optind, optreset; 1653 int i; 1654 char *p, *args; 1655 1656 setproctitle("%s@%s", s->pw->pw_name, INTERNAL_SFTP_NAME); 1657 args = xstrdup(command ? command : "sftp-server"); 1658 for (i = 0, (p = strtok(args, " ")); p; (p = strtok(NULL, " "))) 1659 if (i < ARGV_MAX - 1) 1660 argv[i++] = p; 1661 argv[i] = NULL; 1662 optind = optreset = 1; 1663 __progname = argv[0]; 1664 #ifdef WITH_SELINUX 1665 ssh_selinux_change_context("sftpd_t"); 1666 #endif 1667 exit(sftp_server_main(i, argv, s->pw)); 1668 } 1669 1670 fflush(NULL); 1671 1672 /* Get the last component of the shell name. */ 1673 if ((shell0 = strrchr(shell, '/')) != NULL) 1674 shell0++; 1675 else 1676 shell0 = shell; 1677 1678 /* 1679 * If we have no command, execute the shell. In this case, the shell 1680 * name to be passed in argv[0] is preceded by '-' to indicate that 1681 * this is a login shell. 1682 */ 1683 if (!command) { 1684 char argv0[256]; 1685 1686 /* Start the shell. Set initial character to '-'. */ 1687 argv0[0] = '-'; 1688 1689 if (strlcpy(argv0 + 1, shell0, sizeof(argv0) - 1) 1690 >= sizeof(argv0) - 1) { 1691 errno = EINVAL; 1692 perror(shell); 1693 exit(1); 1694 } 1695 1696 /* Execute the shell. */ 1697 argv[0] = argv0; 1698 argv[1] = NULL; 1699 execve(shell, argv, env); 1700 1701 /* Executing the shell failed. */ 1702 perror(shell); 1703 exit(1); 1704 } 1705 /* 1706 * Execute the command using the user's shell. This uses the -c 1707 * option to execute the command. 1708 */ 1709 argv[0] = (char *) shell0; 1710 argv[1] = "-c"; 1711 argv[2] = (char *) command; 1712 argv[3] = NULL; 1713 execve(shell, argv, env); 1714 perror(shell); 1715 exit(1); 1716 } 1717 1718 void 1719 session_unused(int id) 1720 { 1721 debug3_f("session id %d unused", id); 1722 if (id >= options.max_sessions || 1723 id >= sessions_nalloc) { 1724 fatal_f("insane session id %d (max %d nalloc %d)", 1725 id, options.max_sessions, sessions_nalloc); 1726 } 1727 memset(&sessions[id], 0, sizeof(*sessions)); 1728 sessions[id].self = id; 1729 sessions[id].used = 0; 1730 sessions[id].chanid = -1; 1731 sessions[id].ptyfd = -1; 1732 sessions[id].ttyfd = -1; 1733 sessions[id].ptymaster = -1; 1734 sessions[id].x11_chanids = NULL; 1735 sessions[id].next_unused = sessions_first_unused; 1736 sessions_first_unused = id; 1737 } 1738 1739 Session * 1740 session_new(void) 1741 { 1742 Session *s, *tmp; 1743 1744 if (sessions_first_unused == -1) { 1745 if (sessions_nalloc >= options.max_sessions) 1746 return NULL; 1747 debug2_f("allocate (allocated %d max %d)", 1748 sessions_nalloc, options.max_sessions); 1749 tmp = xrecallocarray(sessions, sessions_nalloc, 1750 sessions_nalloc + 1, sizeof(*sessions)); 1751 if (tmp == NULL) { 1752 error_f("cannot allocate %d sessions", 1753 sessions_nalloc + 1); 1754 return NULL; 1755 } 1756 sessions = tmp; 1757 session_unused(sessions_nalloc++); 1758 } 1759 1760 if (sessions_first_unused >= sessions_nalloc || 1761 sessions_first_unused < 0) { 1762 fatal_f("insane first_unused %d max %d nalloc %d", 1763 sessions_first_unused, options.max_sessions, 1764 sessions_nalloc); 1765 } 1766 1767 s = &sessions[sessions_first_unused]; 1768 if (s->used) 1769 fatal_f("session %d already used", sessions_first_unused); 1770 sessions_first_unused = s->next_unused; 1771 s->used = 1; 1772 s->next_unused = -1; 1773 debug("session_new: session %d", s->self); 1774 1775 return s; 1776 } 1777 1778 static void 1779 session_dump(void) 1780 { 1781 int i; 1782 for (i = 0; i < sessions_nalloc; i++) { 1783 Session *s = &sessions[i]; 1784 1785 debug("dump: used %d next_unused %d session %d " 1786 "channel %d pid %ld", 1787 s->used, 1788 s->next_unused, 1789 s->self, 1790 s->chanid, 1791 (long)s->pid); 1792 } 1793 } 1794 1795 int 1796 session_open(Authctxt *authctxt, int chanid) 1797 { 1798 Session *s = session_new(); 1799 debug("session_open: channel %d", chanid); 1800 if (s == NULL) { 1801 error("no more sessions"); 1802 return 0; 1803 } 1804 s->authctxt = authctxt; 1805 s->pw = authctxt->pw; 1806 if (s->pw == NULL || !authctxt->valid) 1807 fatal("no user for session %d", s->self); 1808 debug("session_open: session %d: link with channel %d", s->self, chanid); 1809 s->chanid = chanid; 1810 return 1; 1811 } 1812 1813 Session * 1814 session_by_tty(char *tty) 1815 { 1816 int i; 1817 for (i = 0; i < sessions_nalloc; i++) { 1818 Session *s = &sessions[i]; 1819 if (s->used && s->ttyfd != -1 && strcmp(s->tty, tty) == 0) { 1820 debug("session_by_tty: session %d tty %s", i, tty); 1821 return s; 1822 } 1823 } 1824 debug("session_by_tty: unknown tty %.100s", tty); 1825 session_dump(); 1826 return NULL; 1827 } 1828 1829 static Session * 1830 session_by_channel(int id) 1831 { 1832 int i; 1833 for (i = 0; i < sessions_nalloc; i++) { 1834 Session *s = &sessions[i]; 1835 if (s->used && s->chanid == id) { 1836 debug("session_by_channel: session %d channel %d", 1837 i, id); 1838 return s; 1839 } 1840 } 1841 debug("session_by_channel: unknown channel %d", id); 1842 session_dump(); 1843 return NULL; 1844 } 1845 1846 static Session * 1847 session_by_x11_channel(int id) 1848 { 1849 int i, j; 1850 1851 for (i = 0; i < sessions_nalloc; i++) { 1852 Session *s = &sessions[i]; 1853 1854 if (s->x11_chanids == NULL || !s->used) 1855 continue; 1856 for (j = 0; s->x11_chanids[j] != -1; j++) { 1857 if (s->x11_chanids[j] == id) { 1858 debug("session_by_x11_channel: session %d " 1859 "channel %d", s->self, id); 1860 return s; 1861 } 1862 } 1863 } 1864 debug("session_by_x11_channel: unknown channel %d", id); 1865 session_dump(); 1866 return NULL; 1867 } 1868 1869 static Session * 1870 session_by_pid(pid_t pid) 1871 { 1872 int i; 1873 debug("session_by_pid: pid %ld", (long)pid); 1874 for (i = 0; i < sessions_nalloc; i++) { 1875 Session *s = &sessions[i]; 1876 if (s->used && s->pid == pid) 1877 return s; 1878 } 1879 error("session_by_pid: unknown pid %ld", (long)pid); 1880 session_dump(); 1881 return NULL; 1882 } 1883 1884 static int 1885 session_window_change_req(struct ssh *ssh, Session *s) 1886 { 1887 int r; 1888 1889 if ((r = sshpkt_get_u32(ssh, &s->col)) != 0 || 1890 (r = sshpkt_get_u32(ssh, &s->row)) != 0 || 1891 (r = sshpkt_get_u32(ssh, &s->xpixel)) != 0 || 1892 (r = sshpkt_get_u32(ssh, &s->ypixel)) != 0 || 1893 (r = sshpkt_get_end(ssh)) != 0) 1894 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 1895 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 1896 return 1; 1897 } 1898 1899 static int 1900 session_pty_req(struct ssh *ssh, Session *s) 1901 { 1902 int r; 1903 1904 if (!auth_opts->permit_pty_flag || !options.permit_tty) { 1905 debug("Allocating a pty not permitted for this connection."); 1906 return 0; 1907 } 1908 if (s->ttyfd != -1) { 1909 ssh_packet_disconnect(ssh, "Protocol error: you already have a pty."); 1910 return 0; 1911 } 1912 1913 if ((r = sshpkt_get_cstring(ssh, &s->term, NULL)) != 0 || 1914 (r = sshpkt_get_u32(ssh, &s->col)) != 0 || 1915 (r = sshpkt_get_u32(ssh, &s->row)) != 0 || 1916 (r = sshpkt_get_u32(ssh, &s->xpixel)) != 0 || 1917 (r = sshpkt_get_u32(ssh, &s->ypixel)) != 0) 1918 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 1919 1920 if (strcmp(s->term, "") == 0) { 1921 free(s->term); 1922 s->term = NULL; 1923 } 1924 1925 /* Allocate a pty and open it. */ 1926 debug("Allocating pty."); 1927 if (!PRIVSEP(pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, 1928 sizeof(s->tty)))) { 1929 free(s->term); 1930 s->term = NULL; 1931 s->ptyfd = -1; 1932 s->ttyfd = -1; 1933 error("session_pty_req: session %d alloc failed", s->self); 1934 return 0; 1935 } 1936 debug("session_pty_req: session %d alloc %s", s->self, s->tty); 1937 1938 ssh_tty_parse_modes(ssh, s->ttyfd); 1939 1940 if ((r = sshpkt_get_end(ssh)) != 0) 1941 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 1942 1943 if (!use_privsep) 1944 pty_setowner(s->pw, s->tty); 1945 1946 /* Set window size from the packet. */ 1947 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 1948 1949 session_proctitle(s); 1950 return 1; 1951 } 1952 1953 static int 1954 session_subsystem_req(struct ssh *ssh, Session *s) 1955 { 1956 struct stat st; 1957 int r, success = 0; 1958 char *prog, *cmd; 1959 u_int i; 1960 1961 if ((r = sshpkt_get_cstring(ssh, &s->subsys, NULL)) != 0 || 1962 (r = sshpkt_get_end(ssh)) != 0) 1963 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 1964 debug2("subsystem request for %.100s by user %s", s->subsys, 1965 s->pw->pw_name); 1966 1967 for (i = 0; i < options.num_subsystems; i++) { 1968 if (strcmp(s->subsys, options.subsystem_name[i]) == 0) { 1969 prog = options.subsystem_command[i]; 1970 cmd = options.subsystem_args[i]; 1971 if (strcmp(INTERNAL_SFTP_NAME, prog) == 0) { 1972 s->is_subsystem = SUBSYSTEM_INT_SFTP; 1973 debug("subsystem: %s", prog); 1974 } else { 1975 if (stat(prog, &st) == -1) 1976 debug("subsystem: cannot stat %s: %s", 1977 prog, strerror(errno)); 1978 s->is_subsystem = SUBSYSTEM_EXT; 1979 debug("subsystem: exec() %s", cmd); 1980 } 1981 success = do_exec(ssh, s, cmd) == 0; 1982 break; 1983 } 1984 } 1985 1986 if (!success) 1987 logit("subsystem request for %.100s by user %s failed, " 1988 "subsystem not found", s->subsys, s->pw->pw_name); 1989 1990 return success; 1991 } 1992 1993 static int 1994 session_x11_req(struct ssh *ssh, Session *s) 1995 { 1996 int r, success; 1997 u_char single_connection = 0; 1998 1999 if (s->auth_proto != NULL || s->auth_data != NULL) { 2000 error("session_x11_req: session %d: " 2001 "x11 forwarding already active", s->self); 2002 return 0; 2003 } 2004 if ((r = sshpkt_get_u8(ssh, &single_connection)) != 0 || 2005 (r = sshpkt_get_cstring(ssh, &s->auth_proto, NULL)) != 0 || 2006 (r = sshpkt_get_cstring(ssh, &s->auth_data, NULL)) != 0 || 2007 (r = sshpkt_get_u32(ssh, &s->screen)) != 0 || 2008 (r = sshpkt_get_end(ssh)) != 0) 2009 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 2010 2011 s->single_connection = single_connection; 2012 2013 if (xauth_valid_string(s->auth_proto) && 2014 xauth_valid_string(s->auth_data)) 2015 success = session_setup_x11fwd(ssh, s); 2016 else { 2017 success = 0; 2018 error("Invalid X11 forwarding data"); 2019 } 2020 if (!success) { 2021 free(s->auth_proto); 2022 free(s->auth_data); 2023 s->auth_proto = NULL; 2024 s->auth_data = NULL; 2025 } 2026 return success; 2027 } 2028 2029 static int 2030 session_shell_req(struct ssh *ssh, Session *s) 2031 { 2032 int r; 2033 2034 if ((r = sshpkt_get_end(ssh)) != 0) 2035 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 2036 return do_exec(ssh, s, NULL) == 0; 2037 } 2038 2039 static int 2040 session_exec_req(struct ssh *ssh, Session *s) 2041 { 2042 u_int success; 2043 int r; 2044 char *command = NULL; 2045 2046 if ((r = sshpkt_get_cstring(ssh, &command, NULL)) != 0 || 2047 (r = sshpkt_get_end(ssh)) != 0) 2048 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 2049 2050 success = do_exec(ssh, s, command) == 0; 2051 free(command); 2052 return success; 2053 } 2054 2055 static int 2056 session_break_req(struct ssh *ssh, Session *s) 2057 { 2058 int r; 2059 2060 if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* ignore */ 2061 (r = sshpkt_get_end(ssh)) != 0) 2062 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 2063 2064 if (s->ptymaster == -1 || tcsendbreak(s->ptymaster, 0) == -1) 2065 return 0; 2066 return 1; 2067 } 2068 2069 static int 2070 session_env_req(struct ssh *ssh, Session *s) 2071 { 2072 char *name, *val; 2073 u_int i; 2074 int r; 2075 2076 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 || 2077 (r = sshpkt_get_cstring(ssh, &val, NULL)) != 0 || 2078 (r = sshpkt_get_end(ssh)) != 0) 2079 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 2080 2081 /* Don't set too many environment variables */ 2082 if (s->num_env > 128) { 2083 debug2("Ignoring env request %s: too many env vars", name); 2084 goto fail; 2085 } 2086 2087 for (i = 0; i < options.num_accept_env; i++) { 2088 if (match_pattern(name, options.accept_env[i])) { 2089 debug2("Setting env %d: %s=%s", s->num_env, name, val); 2090 s->env = xrecallocarray(s->env, s->num_env, 2091 s->num_env + 1, sizeof(*s->env)); 2092 s->env[s->num_env].name = name; 2093 s->env[s->num_env].val = val; 2094 s->num_env++; 2095 return (1); 2096 } 2097 } 2098 debug2("Ignoring env request %s: disallowed name", name); 2099 2100 fail: 2101 free(name); 2102 free(val); 2103 return (0); 2104 } 2105 2106 /* 2107 * Conversion of signals from ssh channel request names. 2108 * Subset of signals from RFC 4254 section 6.10C, with SIGINFO as 2109 * local extension. 2110 */ 2111 static int 2112 name2sig(char *name) 2113 { 2114 #define SSH_SIG(x) if (strcmp(name, #x) == 0) return SIG ## x 2115 SSH_SIG(HUP); 2116 SSH_SIG(INT); 2117 SSH_SIG(KILL); 2118 SSH_SIG(QUIT); 2119 SSH_SIG(TERM); 2120 SSH_SIG(USR1); 2121 SSH_SIG(USR2); 2122 #undef SSH_SIG 2123 #ifdef SIGINFO 2124 if (strcmp(name, "INFO@openssh.com") == 0) 2125 return SIGINFO; 2126 #endif 2127 return -1; 2128 } 2129 2130 static int 2131 session_signal_req(struct ssh *ssh, Session *s) 2132 { 2133 char *signame = NULL; 2134 int r, sig, success = 0; 2135 2136 if ((r = sshpkt_get_cstring(ssh, &signame, NULL)) != 0 || 2137 (r = sshpkt_get_end(ssh)) != 0) { 2138 error_fr(r, "parse"); 2139 goto out; 2140 } 2141 if ((sig = name2sig(signame)) == -1) { 2142 error_f("unsupported signal \"%s\"", signame); 2143 goto out; 2144 } 2145 if (s->pid <= 0) { 2146 error_f("no pid for session %d", s->self); 2147 goto out; 2148 } 2149 if (s->forced || s->is_subsystem) { 2150 error_f("refusing to send signal %s to %s session", 2151 signame, s->forced ? "forced-command" : "subsystem"); 2152 goto out; 2153 } 2154 if (!use_privsep || mm_is_monitor()) { 2155 error_f("session signalling requires privilege separation"); 2156 goto out; 2157 } 2158 2159 debug_f("signal %s, killpg(%ld, %d)", signame, (long)s->pid, sig); 2160 temporarily_use_uid(s->pw); 2161 r = killpg(s->pid, sig); 2162 restore_uid(); 2163 if (r != 0) { 2164 error_f("killpg(%ld, %d): %s", (long)s->pid, 2165 sig, strerror(errno)); 2166 goto out; 2167 } 2168 2169 /* success */ 2170 success = 1; 2171 out: 2172 free(signame); 2173 return success; 2174 } 2175 2176 static int 2177 session_auth_agent_req(struct ssh *ssh, Session *s) 2178 { 2179 static int called = 0; 2180 int r; 2181 2182 if ((r = sshpkt_get_end(ssh)) != 0) 2183 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 2184 if (!auth_opts->permit_agent_forwarding_flag || 2185 !options.allow_agent_forwarding) { 2186 debug_f("agent forwarding disabled"); 2187 return 0; 2188 } 2189 if (called) { 2190 return 0; 2191 } else { 2192 called = 1; 2193 return auth_input_request_forwarding(ssh, s->pw); 2194 } 2195 } 2196 2197 int 2198 session_input_channel_req(struct ssh *ssh, Channel *c, const char *rtype) 2199 { 2200 int success = 0; 2201 Session *s; 2202 2203 if ((s = session_by_channel(c->self)) == NULL) { 2204 logit_f("no session %d req %.100s", c->self, rtype); 2205 return 0; 2206 } 2207 debug_f("session %d req %s", s->self, rtype); 2208 2209 /* 2210 * a session is in LARVAL state until a shell, a command 2211 * or a subsystem is executed 2212 */ 2213 if (c->type == SSH_CHANNEL_LARVAL) { 2214 if (strcmp(rtype, "shell") == 0) { 2215 success = session_shell_req(ssh, s); 2216 } else if (strcmp(rtype, "exec") == 0) { 2217 success = session_exec_req(ssh, s); 2218 } else if (strcmp(rtype, "pty-req") == 0) { 2219 success = session_pty_req(ssh, s); 2220 } else if (strcmp(rtype, "x11-req") == 0) { 2221 success = session_x11_req(ssh, s); 2222 } else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) { 2223 success = session_auth_agent_req(ssh, s); 2224 } else if (strcmp(rtype, "subsystem") == 0) { 2225 success = session_subsystem_req(ssh, s); 2226 } else if (strcmp(rtype, "env") == 0) { 2227 success = session_env_req(ssh, s); 2228 } 2229 } 2230 if (strcmp(rtype, "window-change") == 0) { 2231 success = session_window_change_req(ssh, s); 2232 } else if (strcmp(rtype, "break") == 0) { 2233 success = session_break_req(ssh, s); 2234 } else if (strcmp(rtype, "signal") == 0) { 2235 success = session_signal_req(ssh, s); 2236 } 2237 2238 return success; 2239 } 2240 2241 void 2242 session_set_fds(struct ssh *ssh, Session *s, 2243 int fdin, int fdout, int fderr, int ignore_fderr, int is_tty) 2244 { 2245 /* 2246 * now that have a child and a pipe to the child, 2247 * we can activate our channel and register the fd's 2248 */ 2249 if (s->chanid == -1) 2250 fatal("no channel for session %d", s->self); 2251 channel_set_fds(ssh, s->chanid, 2252 fdout, fdin, fderr, 2253 ignore_fderr ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ, 2254 1, is_tty, CHAN_SES_WINDOW_DEFAULT); 2255 } 2256 2257 /* 2258 * Function to perform pty cleanup. Also called if we get aborted abnormally 2259 * (e.g., due to a dropped connection). 2260 */ 2261 void 2262 session_pty_cleanup2(Session *s) 2263 { 2264 if (s == NULL) { 2265 error_f("no session"); 2266 return; 2267 } 2268 if (s->ttyfd == -1) 2269 return; 2270 2271 debug_f("session %d release %s", s->self, s->tty); 2272 2273 /* Record that the user has logged out. */ 2274 if (s->pid != 0) 2275 record_logout(s->pid, s->tty, s->pw->pw_name); 2276 2277 /* Release the pseudo-tty. */ 2278 if (getuid() == 0) 2279 pty_release(s->tty); 2280 2281 /* 2282 * Close the server side of the socket pairs. We must do this after 2283 * the pty cleanup, so that another process doesn't get this pty 2284 * while we're still cleaning up. 2285 */ 2286 if (s->ptymaster != -1 && close(s->ptymaster) == -1) 2287 error("close(s->ptymaster/%d): %s", 2288 s->ptymaster, strerror(errno)); 2289 2290 /* unlink pty from session */ 2291 s->ttyfd = -1; 2292 } 2293 2294 void 2295 session_pty_cleanup(Session *s) 2296 { 2297 PRIVSEP(session_pty_cleanup2(s)); 2298 } 2299 2300 static char * 2301 sig2name(int sig) 2302 { 2303 #define SSH_SIG(x) if (sig == SIG ## x) return #x 2304 SSH_SIG(ABRT); 2305 SSH_SIG(ALRM); 2306 SSH_SIG(FPE); 2307 SSH_SIG(HUP); 2308 SSH_SIG(ILL); 2309 SSH_SIG(INT); 2310 SSH_SIG(KILL); 2311 SSH_SIG(PIPE); 2312 SSH_SIG(QUIT); 2313 SSH_SIG(SEGV); 2314 SSH_SIG(TERM); 2315 SSH_SIG(USR1); 2316 SSH_SIG(USR2); 2317 #undef SSH_SIG 2318 return "SIG@openssh.com"; 2319 } 2320 2321 static void 2322 session_close_x11(struct ssh *ssh, int id) 2323 { 2324 Channel *c; 2325 2326 if ((c = channel_by_id(ssh, id)) == NULL) { 2327 debug_f("x11 channel %d missing", id); 2328 } else { 2329 /* Detach X11 listener */ 2330 debug_f("detach x11 channel %d", id); 2331 channel_cancel_cleanup(ssh, id); 2332 if (c->ostate != CHAN_OUTPUT_CLOSED) 2333 chan_mark_dead(ssh, c); 2334 } 2335 } 2336 2337 static void 2338 session_close_single_x11(struct ssh *ssh, int id, void *arg) 2339 { 2340 Session *s; 2341 u_int i; 2342 2343 debug3_f("channel %d", id); 2344 channel_cancel_cleanup(ssh, id); 2345 if ((s = session_by_x11_channel(id)) == NULL) 2346 fatal_f("no x11 channel %d", id); 2347 for (i = 0; s->x11_chanids[i] != -1; i++) { 2348 debug_f("session %d: closing channel %d", 2349 s->self, s->x11_chanids[i]); 2350 /* 2351 * The channel "id" is already closing, but make sure we 2352 * close all of its siblings. 2353 */ 2354 if (s->x11_chanids[i] != id) 2355 session_close_x11(ssh, s->x11_chanids[i]); 2356 } 2357 free(s->x11_chanids); 2358 s->x11_chanids = NULL; 2359 free(s->display); 2360 s->display = NULL; 2361 free(s->auth_proto); 2362 s->auth_proto = NULL; 2363 free(s->auth_data); 2364 s->auth_data = NULL; 2365 free(s->auth_display); 2366 s->auth_display = NULL; 2367 } 2368 2369 static void 2370 session_exit_message(struct ssh *ssh, Session *s, int status) 2371 { 2372 Channel *c; 2373 int r; 2374 2375 if ((c = channel_lookup(ssh, s->chanid)) == NULL) 2376 fatal_f("session %d: no channel %d", s->self, s->chanid); 2377 debug_f("session %d channel %d pid %ld", 2378 s->self, s->chanid, (long)s->pid); 2379 2380 if (WIFEXITED(status)) { 2381 channel_request_start(ssh, s->chanid, "exit-status", 0); 2382 if ((r = sshpkt_put_u32(ssh, WEXITSTATUS(status))) != 0 || 2383 (r = sshpkt_send(ssh)) != 0) 2384 sshpkt_fatal(ssh, r, "%s: exit reply", __func__); 2385 } else if (WIFSIGNALED(status)) { 2386 channel_request_start(ssh, s->chanid, "exit-signal", 0); 2387 #ifndef WCOREDUMP 2388 # define WCOREDUMP(x) (0) 2389 #endif 2390 if ((r = sshpkt_put_cstring(ssh, sig2name(WTERMSIG(status)))) != 0 || 2391 (r = sshpkt_put_u8(ssh, WCOREDUMP(status)? 1 : 0)) != 0 || 2392 (r = sshpkt_put_cstring(ssh, "")) != 0 || 2393 (r = sshpkt_put_cstring(ssh, "")) != 0 || 2394 (r = sshpkt_send(ssh)) != 0) 2395 sshpkt_fatal(ssh, r, "%s: exit reply", __func__); 2396 } else { 2397 /* Some weird exit cause. Just exit. */ 2398 ssh_packet_disconnect(ssh, "wait returned status %04x.", status); 2399 } 2400 2401 /* disconnect channel */ 2402 debug_f("release channel %d", s->chanid); 2403 2404 /* 2405 * Adjust cleanup callback attachment to send close messages when 2406 * the channel gets EOF. The session will be then be closed 2407 * by session_close_by_channel when the child sessions close their fds. 2408 */ 2409 channel_register_cleanup(ssh, c->self, session_close_by_channel, 1); 2410 2411 /* 2412 * emulate a write failure with 'chan_write_failed', nobody will be 2413 * interested in data we write. 2414 * Note that we must not call 'chan_read_failed', since there could 2415 * be some more data waiting in the pipe. 2416 */ 2417 if (c->ostate != CHAN_OUTPUT_CLOSED) 2418 chan_write_failed(ssh, c); 2419 } 2420 2421 void 2422 session_close(struct ssh *ssh, Session *s) 2423 { 2424 u_int i; 2425 2426 verbose("Close session: user %s from %.200s port %d id %d", 2427 s->pw->pw_name, 2428 ssh_remote_ipaddr(ssh), 2429 ssh_remote_port(ssh), 2430 s->self); 2431 2432 if (s->ttyfd != -1) 2433 session_pty_cleanup(s); 2434 free(s->term); 2435 free(s->display); 2436 free(s->x11_chanids); 2437 free(s->auth_display); 2438 free(s->auth_data); 2439 free(s->auth_proto); 2440 free(s->subsys); 2441 if (s->env != NULL) { 2442 for (i = 0; i < s->num_env; i++) { 2443 free(s->env[i].name); 2444 free(s->env[i].val); 2445 } 2446 free(s->env); 2447 } 2448 session_proctitle(s); 2449 session_unused(s->self); 2450 } 2451 2452 void 2453 session_close_by_pid(struct ssh *ssh, pid_t pid, int status) 2454 { 2455 Session *s = session_by_pid(pid); 2456 if (s == NULL) { 2457 debug_f("no session for pid %ld", (long)pid); 2458 return; 2459 } 2460 if (s->chanid != -1) 2461 session_exit_message(ssh, s, status); 2462 if (s->ttyfd != -1) 2463 session_pty_cleanup(s); 2464 s->pid = 0; 2465 } 2466 2467 /* 2468 * this is called when a channel dies before 2469 * the session 'child' itself dies 2470 */ 2471 void 2472 session_close_by_channel(struct ssh *ssh, int id, void *arg) 2473 { 2474 Session *s = session_by_channel(id); 2475 u_int i; 2476 2477 if (s == NULL) { 2478 debug_f("no session for id %d", id); 2479 return; 2480 } 2481 debug_f("channel %d child %ld", id, (long)s->pid); 2482 if (s->pid != 0) { 2483 debug_f("channel %d: has child, ttyfd %d", id, s->ttyfd); 2484 /* 2485 * delay detach of session, but release pty, since 2486 * the fd's to the child are already closed 2487 */ 2488 if (s->ttyfd != -1) 2489 session_pty_cleanup(s); 2490 return; 2491 } 2492 /* detach by removing callback */ 2493 channel_cancel_cleanup(ssh, s->chanid); 2494 2495 /* Close any X11 listeners associated with this session */ 2496 if (s->x11_chanids != NULL) { 2497 for (i = 0; s->x11_chanids[i] != -1; i++) { 2498 session_close_x11(ssh, s->x11_chanids[i]); 2499 s->x11_chanids[i] = -1; 2500 } 2501 } 2502 2503 s->chanid = -1; 2504 session_close(ssh, s); 2505 } 2506 2507 void 2508 session_destroy_all(struct ssh *ssh, void (*closefunc)(Session *)) 2509 { 2510 int i; 2511 for (i = 0; i < sessions_nalloc; i++) { 2512 Session *s = &sessions[i]; 2513 if (s->used) { 2514 if (closefunc != NULL) 2515 closefunc(s); 2516 else 2517 session_close(ssh, s); 2518 } 2519 } 2520 } 2521 2522 static char * 2523 session_tty_list(void) 2524 { 2525 static char buf[1024]; 2526 int i; 2527 char *cp; 2528 2529 buf[0] = '\0'; 2530 for (i = 0; i < sessions_nalloc; i++) { 2531 Session *s = &sessions[i]; 2532 if (s->used && s->ttyfd != -1) { 2533 2534 if (strncmp(s->tty, "/dev/", 5) != 0) { 2535 cp = strrchr(s->tty, '/'); 2536 cp = (cp == NULL) ? s->tty : cp + 1; 2537 } else 2538 cp = s->tty + 5; 2539 2540 if (buf[0] != '\0') 2541 strlcat(buf, ",", sizeof buf); 2542 strlcat(buf, cp, sizeof buf); 2543 } 2544 } 2545 if (buf[0] == '\0') 2546 strlcpy(buf, "notty", sizeof buf); 2547 return buf; 2548 } 2549 2550 void 2551 session_proctitle(Session *s) 2552 { 2553 if (s->pw == NULL) 2554 error("no user for session %d", s->self); 2555 else 2556 setproctitle("%s@%s", s->pw->pw_name, session_tty_list()); 2557 } 2558 2559 int 2560 session_setup_x11fwd(struct ssh *ssh, Session *s) 2561 { 2562 struct stat st; 2563 char display[512], auth_display[512]; 2564 char hostname[NI_MAXHOST]; 2565 u_int i; 2566 2567 if (!auth_opts->permit_x11_forwarding_flag) { 2568 ssh_packet_send_debug(ssh, "X11 forwarding disabled by key options."); 2569 return 0; 2570 } 2571 if (!options.x11_forwarding) { 2572 debug("X11 forwarding disabled in server configuration file."); 2573 return 0; 2574 } 2575 if (options.xauth_location == NULL || 2576 (stat(options.xauth_location, &st) == -1)) { 2577 ssh_packet_send_debug(ssh, "No xauth program; cannot forward X11."); 2578 return 0; 2579 } 2580 if (s->display != NULL) { 2581 debug("X11 display already set."); 2582 return 0; 2583 } 2584 if (x11_create_display_inet(ssh, options.x11_display_offset, 2585 options.x11_use_localhost, s->single_connection, 2586 &s->display_number, &s->x11_chanids) == -1) { 2587 debug("x11_create_display_inet failed."); 2588 return 0; 2589 } 2590 for (i = 0; s->x11_chanids[i] != -1; i++) { 2591 channel_register_cleanup(ssh, s->x11_chanids[i], 2592 session_close_single_x11, 0); 2593 } 2594 2595 /* Set up a suitable value for the DISPLAY variable. */ 2596 if (gethostname(hostname, sizeof(hostname)) == -1) 2597 fatal("gethostname: %.100s", strerror(errno)); 2598 /* 2599 * auth_display must be used as the displayname when the 2600 * authorization entry is added with xauth(1). This will be 2601 * different than the DISPLAY string for localhost displays. 2602 */ 2603 if (options.x11_use_localhost) { 2604 snprintf(display, sizeof display, "localhost:%u.%u", 2605 s->display_number, s->screen); 2606 snprintf(auth_display, sizeof auth_display, "unix:%u.%u", 2607 s->display_number, s->screen); 2608 s->display = xstrdup(display); 2609 s->auth_display = xstrdup(auth_display); 2610 } else { 2611 #ifdef IPADDR_IN_DISPLAY 2612 struct hostent *he; 2613 struct in_addr my_addr; 2614 2615 he = gethostbyname(hostname); 2616 if (he == NULL) { 2617 error("Can't get IP address for X11 DISPLAY."); 2618 ssh_packet_send_debug(ssh, "Can't get IP address for X11 DISPLAY."); 2619 return 0; 2620 } 2621 memcpy(&my_addr, he->h_addr_list[0], sizeof(struct in_addr)); 2622 snprintf(display, sizeof display, "%.50s:%u.%u", inet_ntoa(my_addr), 2623 s->display_number, s->screen); 2624 #else 2625 snprintf(display, sizeof display, "%.400s:%u.%u", hostname, 2626 s->display_number, s->screen); 2627 #endif 2628 s->display = xstrdup(display); 2629 s->auth_display = xstrdup(display); 2630 } 2631 2632 return 1; 2633 } 2634 2635 static void 2636 do_authenticated2(struct ssh *ssh, Authctxt *authctxt) 2637 { 2638 server_loop2(ssh, authctxt); 2639 } 2640 2641 void 2642 do_cleanup(struct ssh *ssh, Authctxt *authctxt) 2643 { 2644 static int called = 0; 2645 2646 debug("do_cleanup"); 2647 2648 /* no cleanup if we're in the child for login shell */ 2649 if (is_child) 2650 return; 2651 2652 /* avoid double cleanup */ 2653 if (called) 2654 return; 2655 called = 1; 2656 2657 if (authctxt == NULL) 2658 return; 2659 2660 #ifdef USE_PAM 2661 if (options.use_pam) { 2662 sshpam_cleanup(); 2663 sshpam_thread_cleanup(); 2664 } 2665 #endif 2666 2667 if (!authctxt->authenticated) 2668 return; 2669 2670 #ifdef KRB5 2671 if (options.kerberos_ticket_cleanup && 2672 authctxt->krb5_ctx) 2673 krb5_cleanup_proc(authctxt); 2674 #endif 2675 2676 #ifdef GSSAPI 2677 if (options.gss_cleanup_creds) 2678 ssh_gssapi_cleanup_creds(); 2679 #endif 2680 2681 /* remove agent socket */ 2682 auth_sock_cleanup_proc(authctxt->pw); 2683 2684 /* remove userauth info */ 2685 if (auth_info_file != NULL) { 2686 temporarily_use_uid(authctxt->pw); 2687 unlink(auth_info_file); 2688 restore_uid(); 2689 free(auth_info_file); 2690 auth_info_file = NULL; 2691 } 2692 2693 /* 2694 * Cleanup ptys/utmp only if privsep is disabled, 2695 * or if running in monitor. 2696 */ 2697 if (!use_privsep || mm_is_monitor()) 2698 session_destroy_all(ssh, session_pty_cleanup2); 2699 } 2700 2701 /* Return a name for the remote host that fits inside utmp_size */ 2702 2703 const char * 2704 session_get_remote_name_or_ip(struct ssh *ssh, u_int utmp_size, int use_dns) 2705 { 2706 const char *remote = ""; 2707 2708 if (utmp_size > 0) 2709 remote = auth_get_canonical_hostname(ssh, use_dns); 2710 if (utmp_size == 0 || strlen(remote) > utmp_size) 2711 remote = ssh_remote_ipaddr(ssh); 2712 return remote; 2713 } 2714 2715