1 /* $OpenBSD: session.c,v 1.329 2021/08/11 05:20:17 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_fr(r, "sshbuf_put_u8"); 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_f("mkstemp: %s", strerror(errno)); 273 goto out; 274 } 275 if (atomicio(vwrite, fd, sshbuf_mutable_ptr(info), 276 sshbuf_len(info)) != sshbuf_len(info)) { 277 error_f("write: %s", strerror(errno)); 278 goto out; 279 } 280 if (close(fd) != 0) { 281 error_f("close: %s", 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_f("internal error: hpdelim"); 309 host = cleanhostname(host); 310 if (cp == NULL || (port = permitopen_port(cp)) < 0) 311 fatal_f("internal error: permitopen port"); 312 channel_add_permission(ssh, 313 FORWARD_USER, FORWARD_LOCAL, host, port); 314 free(tmp); 315 } 316 } 317 if ((options.allow_tcp_forwarding & FORWARD_REMOTE) != 0) { 318 channel_clear_permission(ssh, FORWARD_USER, FORWARD_REMOTE); 319 for (i = 0; i < auth_opts->npermitlisten; i++) { 320 tmp = cp = xstrdup(auth_opts->permitlisten[i]); 321 /* This shouldn't fail as it has already been checked */ 322 if ((host = hpdelim(&cp)) == NULL) 323 fatal_f("internal error: hpdelim"); 324 host = cleanhostname(host); 325 if (cp == NULL || (port = permitopen_port(cp)) < 0) 326 fatal_f("internal error: permitlisten port"); 327 channel_add_permission(ssh, 328 FORWARD_USER, FORWARD_REMOTE, host, port); 329 free(tmp); 330 } 331 } 332 } 333 334 void 335 do_authenticated(struct ssh *ssh, Authctxt *authctxt) 336 { 337 setproctitle("%s", authctxt->pw->pw_name); 338 339 auth_log_authopts("active", auth_opts, 0); 340 341 /* setup the channel layer */ 342 /* XXX - streamlocal? */ 343 set_fwdpermit_from_authopts(ssh, auth_opts); 344 345 if (!auth_opts->permit_port_forwarding_flag || 346 options.disable_forwarding) { 347 channel_disable_admin(ssh, FORWARD_LOCAL); 348 channel_disable_admin(ssh, FORWARD_REMOTE); 349 } else { 350 if ((options.allow_tcp_forwarding & FORWARD_LOCAL) == 0) 351 channel_disable_admin(ssh, FORWARD_LOCAL); 352 else 353 channel_permit_all(ssh, FORWARD_LOCAL); 354 if ((options.allow_tcp_forwarding & FORWARD_REMOTE) == 0) 355 channel_disable_admin(ssh, FORWARD_REMOTE); 356 else 357 channel_permit_all(ssh, FORWARD_REMOTE); 358 } 359 auth_debug_send(ssh); 360 361 prepare_auth_info_file(authctxt->pw, authctxt->session_info); 362 363 do_authenticated2(ssh, authctxt); 364 365 do_cleanup(ssh, authctxt); 366 } 367 368 /* Check untrusted xauth strings for metacharacters */ 369 static int 370 xauth_valid_string(const char *s) 371 { 372 size_t i; 373 374 for (i = 0; s[i] != '\0'; i++) { 375 if (!isalnum((u_char)s[i]) && 376 s[i] != '.' && s[i] != ':' && s[i] != '/' && 377 s[i] != '-' && s[i] != '_') 378 return 0; 379 } 380 return 1; 381 } 382 383 #define USE_PIPES 1 384 /* 385 * This is called to fork and execute a command when we have no tty. This 386 * will call do_child from the child, and server_loop from the parent after 387 * setting up file descriptors and such. 388 */ 389 int 390 do_exec_no_pty(struct ssh *ssh, Session *s, const char *command) 391 { 392 pid_t pid; 393 #ifdef USE_PIPES 394 int pin[2], pout[2], perr[2]; 395 396 if (s == NULL) 397 fatal("do_exec_no_pty: no session"); 398 399 /* Allocate pipes for communicating with the program. */ 400 if (pipe(pin) == -1) { 401 error_f("pipe in: %.100s", strerror(errno)); 402 return -1; 403 } 404 if (pipe(pout) == -1) { 405 error_f("pipe out: %.100s", strerror(errno)); 406 close(pin[0]); 407 close(pin[1]); 408 return -1; 409 } 410 if (pipe(perr) == -1) { 411 error_f("pipe err: %.100s", strerror(errno)); 412 close(pin[0]); 413 close(pin[1]); 414 close(pout[0]); 415 close(pout[1]); 416 return -1; 417 } 418 #else 419 int inout[2], err[2]; 420 421 if (s == NULL) 422 fatal("do_exec_no_pty: no session"); 423 424 /* Uses socket pairs to communicate with the program. */ 425 if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) == -1) { 426 error_f("socketpair #1: %.100s", strerror(errno)); 427 return -1; 428 } 429 if (socketpair(AF_UNIX, SOCK_STREAM, 0, err) == -1) { 430 error_f("socketpair #2: %.100s", strerror(errno)); 431 close(inout[0]); 432 close(inout[1]); 433 return -1; 434 } 435 #endif 436 437 session_proctitle(s); 438 439 /* Fork the child. */ 440 switch ((pid = fork())) { 441 case -1: 442 error_f("fork: %.100s", strerror(errno)); 443 #ifdef USE_PIPES 444 close(pin[0]); 445 close(pin[1]); 446 close(pout[0]); 447 close(pout[1]); 448 close(perr[0]); 449 close(perr[1]); 450 #else 451 close(inout[0]); 452 close(inout[1]); 453 close(err[0]); 454 close(err[1]); 455 #endif 456 return -1; 457 case 0: 458 is_child = 1; 459 460 /* 461 * Create a new session and process group since the 4.4BSD 462 * setlogin() affects the entire process group. 463 */ 464 if (setsid() == -1) 465 error("setsid failed: %.100s", strerror(errno)); 466 467 #ifdef USE_PIPES 468 /* 469 * Redirect stdin. We close the parent side of the socket 470 * pair, and make the child side the standard input. 471 */ 472 close(pin[1]); 473 if (dup2(pin[0], 0) == -1) 474 perror("dup2 stdin"); 475 close(pin[0]); 476 477 /* Redirect stdout. */ 478 close(pout[0]); 479 if (dup2(pout[1], 1) == -1) 480 perror("dup2 stdout"); 481 close(pout[1]); 482 483 /* Redirect stderr. */ 484 close(perr[0]); 485 if (dup2(perr[1], 2) == -1) 486 perror("dup2 stderr"); 487 close(perr[1]); 488 #else 489 /* 490 * Redirect stdin, stdout, and stderr. Stdin and stdout will 491 * use the same socket, as some programs (particularly rdist) 492 * seem to depend on it. 493 */ 494 close(inout[1]); 495 close(err[1]); 496 if (dup2(inout[0], 0) == -1) /* stdin */ 497 perror("dup2 stdin"); 498 if (dup2(inout[0], 1) == -1) /* stdout (same as stdin) */ 499 perror("dup2 stdout"); 500 close(inout[0]); 501 if (dup2(err[0], 2) == -1) /* stderr */ 502 perror("dup2 stderr"); 503 close(err[0]); 504 #endif 505 506 /* Do processing for the child (exec command etc). */ 507 do_child(ssh, s, command); 508 /* NOTREACHED */ 509 default: 510 break; 511 } 512 513 #ifdef HAVE_CYGWIN 514 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); 515 #endif 516 517 s->pid = pid; 518 /* Set interactive/non-interactive mode. */ 519 ssh_packet_set_interactive(ssh, s->display != NULL, 520 options.ip_qos_interactive, options.ip_qos_bulk); 521 522 /* 523 * Clear loginmsg, since it's the child's responsibility to display 524 * it to the user, otherwise multiple sessions may accumulate 525 * multiple copies of the login messages. 526 */ 527 sshbuf_reset(loginmsg); 528 529 #ifdef USE_PIPES 530 /* We are the parent. Close the child sides of the pipes. */ 531 close(pin[0]); 532 close(pout[1]); 533 close(perr[1]); 534 535 session_set_fds(ssh, s, pin[1], pout[0], perr[0], 536 s->is_subsystem, 0); 537 #else 538 /* We are the parent. Close the child sides of the socket pairs. */ 539 close(inout[0]); 540 close(err[0]); 541 542 /* 543 * Enter the interactive session. Note: server_loop must be able to 544 * handle the case that fdin and fdout are the same. 545 */ 546 session_set_fds(ssh, s, inout[1], inout[1], err[1], 547 s->is_subsystem, 0); 548 #endif 549 return 0; 550 } 551 552 /* 553 * This is called to fork and execute a command when we have a tty. This 554 * will call do_child from the child, and server_loop from the parent after 555 * setting up file descriptors, controlling tty, updating wtmp, utmp, 556 * lastlog, and other such operations. 557 */ 558 int 559 do_exec_pty(struct ssh *ssh, Session *s, const char *command) 560 { 561 int fdout, ptyfd, ttyfd, ptymaster; 562 pid_t pid; 563 564 if (s == NULL) 565 fatal("do_exec_pty: no session"); 566 ptyfd = s->ptyfd; 567 ttyfd = s->ttyfd; 568 569 /* 570 * Create another descriptor of the pty master side for use as the 571 * standard input. We could use the original descriptor, but this 572 * simplifies code in server_loop. The descriptor is bidirectional. 573 * Do this before forking (and cleanup in the child) so as to 574 * detect and gracefully fail out-of-fd conditions. 575 */ 576 if ((fdout = dup(ptyfd)) == -1) { 577 error_f("dup #1: %s", strerror(errno)); 578 close(ttyfd); 579 close(ptyfd); 580 return -1; 581 } 582 /* we keep a reference to the pty master */ 583 if ((ptymaster = dup(ptyfd)) == -1) { 584 error_f("dup #2: %s", strerror(errno)); 585 close(ttyfd); 586 close(ptyfd); 587 close(fdout); 588 return -1; 589 } 590 591 /* Fork the child. */ 592 switch ((pid = fork())) { 593 case -1: 594 error_f("fork: %.100s", strerror(errno)); 595 close(fdout); 596 close(ptymaster); 597 close(ttyfd); 598 close(ptyfd); 599 return -1; 600 case 0: 601 is_child = 1; 602 603 close(fdout); 604 close(ptymaster); 605 606 /* Close the master side of the pseudo tty. */ 607 close(ptyfd); 608 609 /* Make the pseudo tty our controlling tty. */ 610 pty_make_controlling_tty(&ttyfd, s->tty); 611 612 /* Redirect stdin/stdout/stderr from the pseudo tty. */ 613 if (dup2(ttyfd, 0) == -1) 614 error("dup2 stdin: %s", strerror(errno)); 615 if (dup2(ttyfd, 1) == -1) 616 error("dup2 stdout: %s", strerror(errno)); 617 if (dup2(ttyfd, 2) == -1) 618 error("dup2 stderr: %s", strerror(errno)); 619 620 /* Close the extra descriptor for the pseudo tty. */ 621 close(ttyfd); 622 623 /* record login, etc. similar to login(1) */ 624 #ifndef HAVE_OSF_SIA 625 do_login(ssh, s, command); 626 #endif 627 /* 628 * Do common processing for the child, such as execing 629 * the command. 630 */ 631 do_child(ssh, s, command); 632 /* NOTREACHED */ 633 default: 634 break; 635 } 636 637 #ifdef HAVE_CYGWIN 638 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); 639 #endif 640 641 s->pid = pid; 642 643 /* Parent. Close the slave side of the pseudo tty. */ 644 close(ttyfd); 645 646 /* Enter interactive session. */ 647 s->ptymaster = ptymaster; 648 ssh_packet_set_interactive(ssh, 1, 649 options.ip_qos_interactive, options.ip_qos_bulk); 650 session_set_fds(ssh, s, ptyfd, fdout, -1, 1, 1); 651 return 0; 652 } 653 654 /* 655 * This is called to fork and execute a command. If another command is 656 * to be forced, execute that instead. 657 */ 658 int 659 do_exec(struct ssh *ssh, Session *s, const char *command) 660 { 661 int ret; 662 const char *forced = NULL, *tty = NULL; 663 char session_type[1024]; 664 665 if (options.adm_forced_command) { 666 original_command = command; 667 command = options.adm_forced_command; 668 forced = "(config)"; 669 } else if (auth_opts->force_command != NULL) { 670 original_command = command; 671 command = auth_opts->force_command; 672 forced = "(key-option)"; 673 } 674 s->forced = 0; 675 if (forced != NULL) { 676 s->forced = 1; 677 if (IS_INTERNAL_SFTP(command)) { 678 s->is_subsystem = s->is_subsystem ? 679 SUBSYSTEM_INT_SFTP : SUBSYSTEM_INT_SFTP_ERROR; 680 } else if (s->is_subsystem) 681 s->is_subsystem = SUBSYSTEM_EXT; 682 snprintf(session_type, sizeof(session_type), 683 "forced-command %s '%.900s'", forced, command); 684 } else if (s->is_subsystem) { 685 snprintf(session_type, sizeof(session_type), 686 "subsystem '%.900s'", s->subsys); 687 } else if (command == NULL) { 688 snprintf(session_type, sizeof(session_type), "shell"); 689 } else { 690 /* NB. we don't log unforced commands to preserve privacy */ 691 snprintf(session_type, sizeof(session_type), "command"); 692 } 693 694 if (s->ttyfd != -1) { 695 tty = s->tty; 696 if (strncmp(tty, "/dev/", 5) == 0) 697 tty += 5; 698 } 699 700 verbose("Starting session: %s%s%s for %s from %.200s port %d id %d", 701 session_type, 702 tty == NULL ? "" : " on ", 703 tty == NULL ? "" : tty, 704 s->pw->pw_name, 705 ssh_remote_ipaddr(ssh), 706 ssh_remote_port(ssh), 707 s->self); 708 709 #ifdef SSH_AUDIT_EVENTS 710 if (command != NULL) 711 PRIVSEP(audit_run_command(command)); 712 else if (s->ttyfd == -1) { 713 char *shell = s->pw->pw_shell; 714 715 if (shell[0] == '\0') /* empty shell means /bin/sh */ 716 shell =_PATH_BSHELL; 717 PRIVSEP(audit_run_command(shell)); 718 } 719 #endif 720 if (s->ttyfd != -1) 721 ret = do_exec_pty(ssh, s, command); 722 else 723 ret = do_exec_no_pty(ssh, s, command); 724 725 original_command = NULL; 726 727 /* 728 * Clear loginmsg: it's the child's responsibility to display 729 * it to the user, otherwise multiple sessions may accumulate 730 * multiple copies of the login messages. 731 */ 732 sshbuf_reset(loginmsg); 733 734 return ret; 735 } 736 737 /* administrative, login(1)-like work */ 738 void 739 do_login(struct ssh *ssh, Session *s, const char *command) 740 { 741 socklen_t fromlen; 742 struct sockaddr_storage from; 743 struct passwd * pw = s->pw; 744 pid_t pid = getpid(); 745 746 /* 747 * Get IP address of client. If the connection is not a socket, let 748 * the address be 0.0.0.0. 749 */ 750 memset(&from, 0, sizeof(from)); 751 fromlen = sizeof(from); 752 if (ssh_packet_connection_is_on_socket(ssh)) { 753 if (getpeername(ssh_packet_get_connection_in(ssh), 754 (struct sockaddr *)&from, &fromlen) == -1) { 755 debug("getpeername: %.100s", strerror(errno)); 756 cleanup_exit(255); 757 } 758 } 759 760 /* Record that there was a login on that tty from the remote host. */ 761 if (!use_privsep) 762 record_login(pid, s->tty, pw->pw_name, pw->pw_uid, 763 session_get_remote_name_or_ip(ssh, utmp_len, 764 options.use_dns), 765 (struct sockaddr *)&from, fromlen); 766 767 #ifdef USE_PAM 768 /* 769 * If password change is needed, do it now. 770 * This needs to occur before the ~/.hushlogin check. 771 */ 772 if (options.use_pam && !use_privsep && s->authctxt->force_pwchange) { 773 display_loginmsg(); 774 do_pam_chauthtok(); 775 s->authctxt->force_pwchange = 0; 776 /* XXX - signal [net] parent to enable forwardings */ 777 } 778 #endif 779 780 if (check_quietlogin(s, command)) 781 return; 782 783 display_loginmsg(); 784 785 do_motd(); 786 } 787 788 /* 789 * Display the message of the day. 790 */ 791 void 792 do_motd(void) 793 { 794 FILE *f; 795 char buf[256]; 796 797 if (options.print_motd) { 798 #ifdef HAVE_LOGIN_CAP 799 f = fopen(login_getcapstr(lc, "welcome", "/etc/motd", 800 "/etc/motd"), "r"); 801 #else 802 f = fopen("/etc/motd", "r"); 803 #endif 804 if (f) { 805 while (fgets(buf, sizeof(buf), f)) 806 fputs(buf, stdout); 807 fclose(f); 808 } 809 } 810 } 811 812 813 /* 814 * Check for quiet login, either .hushlogin or command given. 815 */ 816 int 817 check_quietlogin(Session *s, const char *command) 818 { 819 char buf[256]; 820 struct passwd *pw = s->pw; 821 struct stat st; 822 823 /* Return 1 if .hushlogin exists or a command given. */ 824 if (command != NULL) 825 return 1; 826 snprintf(buf, sizeof(buf), "%.200s/.hushlogin", pw->pw_dir); 827 #ifdef HAVE_LOGIN_CAP 828 if (login_getcapbool(lc, "hushlogin", 0) || stat(buf, &st) >= 0) 829 return 1; 830 #else 831 if (stat(buf, &st) >= 0) 832 return 1; 833 #endif 834 return 0; 835 } 836 837 /* 838 * Reads environment variables from the given file and adds/overrides them 839 * into the environment. If the file does not exist, this does nothing. 840 * Otherwise, it must consist of empty lines, comments (line starts with '#') 841 * and assignments of the form name=value. No other forms are allowed. 842 * If allowlist is not NULL, then it is interpreted as a pattern list and 843 * only variable names that match it will be accepted. 844 */ 845 static void 846 read_environment_file(char ***env, u_int *envsize, 847 const char *filename, const char *allowlist) 848 { 849 FILE *f; 850 char *line = NULL, *cp, *value; 851 size_t linesize = 0; 852 u_int lineno = 0; 853 854 f = fopen(filename, "r"); 855 if (!f) 856 return; 857 858 while (getline(&line, &linesize, f) != -1) { 859 if (++lineno > 1000) 860 fatal("Too many lines in environment file %s", filename); 861 for (cp = line; *cp == ' ' || *cp == '\t'; cp++) 862 ; 863 if (!*cp || *cp == '#' || *cp == '\n') 864 continue; 865 866 cp[strcspn(cp, "\n")] = '\0'; 867 868 value = strchr(cp, '='); 869 if (value == NULL) { 870 fprintf(stderr, "Bad line %u in %.100s\n", lineno, 871 filename); 872 continue; 873 } 874 /* 875 * Replace the equals sign by nul, and advance value to 876 * the value string. 877 */ 878 *value = '\0'; 879 value++; 880 if (allowlist != NULL && 881 match_pattern_list(cp, allowlist, 0) != 1) 882 continue; 883 child_set_env(env, envsize, cp, value); 884 } 885 free(line); 886 fclose(f); 887 } 888 889 #ifdef HAVE_ETC_DEFAULT_LOGIN 890 /* 891 * Return named variable from specified environment, or NULL if not present. 892 */ 893 static char * 894 child_get_env(char **env, const char *name) 895 { 896 int i; 897 size_t len; 898 899 len = strlen(name); 900 for (i=0; env[i] != NULL; i++) 901 if (strncmp(name, env[i], len) == 0 && env[i][len] == '=') 902 return(env[i] + len + 1); 903 return NULL; 904 } 905 906 /* 907 * Read /etc/default/login. 908 * We pick up the PATH (or SUPATH for root) and UMASK. 909 */ 910 static void 911 read_etc_default_login(char ***env, u_int *envsize, uid_t uid) 912 { 913 char **tmpenv = NULL, *var; 914 u_int i, tmpenvsize = 0; 915 u_long mask; 916 917 /* 918 * We don't want to copy the whole file to the child's environment, 919 * so we use a temporary environment and copy the variables we're 920 * interested in. 921 */ 922 read_environment_file(&tmpenv, &tmpenvsize, "/etc/default/login", 923 options.permit_user_env_allowlist); 924 925 if (tmpenv == NULL) 926 return; 927 928 if (uid == 0) 929 var = child_get_env(tmpenv, "SUPATH"); 930 else 931 var = child_get_env(tmpenv, "PATH"); 932 if (var != NULL) 933 child_set_env(env, envsize, "PATH", var); 934 935 if ((var = child_get_env(tmpenv, "UMASK")) != NULL) 936 if (sscanf(var, "%5lo", &mask) == 1) 937 umask((mode_t)mask); 938 939 for (i = 0; tmpenv[i] != NULL; i++) 940 free(tmpenv[i]); 941 free(tmpenv); 942 } 943 #endif /* HAVE_ETC_DEFAULT_LOGIN */ 944 945 #if defined(USE_PAM) || defined(HAVE_CYGWIN) 946 static void 947 copy_environment_denylist(char **source, char ***env, u_int *envsize, 948 const char *denylist) 949 { 950 char *var_name, *var_val; 951 int i; 952 953 if (source == NULL) 954 return; 955 956 for(i = 0; source[i] != NULL; i++) { 957 var_name = xstrdup(source[i]); 958 if ((var_val = strstr(var_name, "=")) == NULL) { 959 free(var_name); 960 continue; 961 } 962 *var_val++ = '\0'; 963 964 if (denylist == NULL || 965 match_pattern_list(var_name, denylist, 0) != 1) { 966 debug3("Copy environment: %s=%s", var_name, var_val); 967 child_set_env(env, envsize, var_name, var_val); 968 } 969 970 free(var_name); 971 } 972 } 973 #endif /* defined(USE_PAM) || defined(HAVE_CYGWIN) */ 974 975 #ifdef HAVE_CYGWIN 976 static void 977 copy_environment(char **source, char ***env, u_int *envsize) 978 { 979 copy_environment_denylist(source, env, envsize, NULL); 980 } 981 #endif 982 983 static char ** 984 do_setup_env(struct ssh *ssh, Session *s, const char *shell) 985 { 986 char buf[256]; 987 size_t n; 988 u_int i, envsize; 989 char *ocp, *cp, *value, **env, *laddr; 990 struct passwd *pw = s->pw; 991 #if !defined (HAVE_LOGIN_CAP) && !defined (HAVE_CYGWIN) 992 char *path = NULL; 993 #endif 994 995 /* Initialize the environment. */ 996 envsize = 100; 997 env = xcalloc(envsize, sizeof(char *)); 998 env[0] = NULL; 999 1000 #ifdef HAVE_CYGWIN 1001 /* 1002 * The Windows environment contains some setting which are 1003 * important for a running system. They must not be dropped. 1004 */ 1005 { 1006 char **p; 1007 1008 p = fetch_windows_environment(); 1009 copy_environment(p, &env, &envsize); 1010 free_windows_environment(p); 1011 } 1012 #endif 1013 1014 #ifdef GSSAPI 1015 /* Allow any GSSAPI methods that we've used to alter 1016 * the child's environment as they see fit 1017 */ 1018 ssh_gssapi_do_child(&env, &envsize); 1019 #endif 1020 1021 /* Set basic environment. */ 1022 for (i = 0; i < s->num_env; i++) 1023 child_set_env(&env, &envsize, s->env[i].name, s->env[i].val); 1024 1025 child_set_env(&env, &envsize, "USER", pw->pw_name); 1026 child_set_env(&env, &envsize, "LOGNAME", pw->pw_name); 1027 #ifdef _AIX 1028 child_set_env(&env, &envsize, "LOGIN", pw->pw_name); 1029 #endif 1030 child_set_env(&env, &envsize, "HOME", pw->pw_dir); 1031 #ifdef HAVE_LOGIN_CAP 1032 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETPATH) < 0) 1033 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); 1034 else 1035 child_set_env(&env, &envsize, "PATH", getenv("PATH")); 1036 #else /* HAVE_LOGIN_CAP */ 1037 # ifndef HAVE_CYGWIN 1038 /* 1039 * There's no standard path on Windows. The path contains 1040 * important components pointing to the system directories, 1041 * needed for loading shared libraries. So the path better 1042 * remains intact here. 1043 */ 1044 # ifdef HAVE_ETC_DEFAULT_LOGIN 1045 read_etc_default_login(&env, &envsize, pw->pw_uid); 1046 path = child_get_env(env, "PATH"); 1047 # endif /* HAVE_ETC_DEFAULT_LOGIN */ 1048 if (path == NULL || *path == '\0') { 1049 child_set_env(&env, &envsize, "PATH", 1050 s->pw->pw_uid == 0 ? SUPERUSER_PATH : _PATH_STDPATH); 1051 } 1052 # endif /* HAVE_CYGWIN */ 1053 #endif /* HAVE_LOGIN_CAP */ 1054 1055 if (!options.use_pam) { 1056 snprintf(buf, sizeof buf, "%.200s/%.50s", 1057 _PATH_MAILDIR, pw->pw_name); 1058 child_set_env(&env, &envsize, "MAIL", buf); 1059 } 1060 1061 /* Normal systems set SHELL by default. */ 1062 child_set_env(&env, &envsize, "SHELL", shell); 1063 1064 if (getenv("TZ")) 1065 child_set_env(&env, &envsize, "TZ", getenv("TZ")); 1066 if (s->term) 1067 child_set_env(&env, &envsize, "TERM", s->term); 1068 if (s->display) 1069 child_set_env(&env, &envsize, "DISPLAY", s->display); 1070 1071 /* 1072 * Since we clear KRB5CCNAME at startup, if it's set now then it 1073 * must have been set by a native authentication method (eg AIX or 1074 * SIA), so copy it to the child. 1075 */ 1076 { 1077 char *cp; 1078 1079 if ((cp = getenv("KRB5CCNAME")) != NULL) 1080 child_set_env(&env, &envsize, "KRB5CCNAME", cp); 1081 } 1082 1083 #ifdef _AIX 1084 { 1085 char *cp; 1086 1087 if ((cp = getenv("AUTHSTATE")) != NULL) 1088 child_set_env(&env, &envsize, "AUTHSTATE", cp); 1089 read_environment_file(&env, &envsize, "/etc/environment", 1090 options.permit_user_env_allowlist); 1091 } 1092 #endif 1093 #ifdef KRB5 1094 if (s->authctxt->krb5_ccname) 1095 child_set_env(&env, &envsize, "KRB5CCNAME", 1096 s->authctxt->krb5_ccname); 1097 #endif 1098 if (auth_sock_name != NULL) 1099 child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME, 1100 auth_sock_name); 1101 1102 1103 /* Set custom environment options from pubkey authentication. */ 1104 if (options.permit_user_env) { 1105 for (n = 0 ; n < auth_opts->nenv; n++) { 1106 ocp = xstrdup(auth_opts->env[n]); 1107 cp = strchr(ocp, '='); 1108 if (cp != NULL) { 1109 *cp = '\0'; 1110 /* Apply PermitUserEnvironment allowlist */ 1111 if (options.permit_user_env_allowlist == NULL || 1112 match_pattern_list(ocp, 1113 options.permit_user_env_allowlist, 0) == 1) 1114 child_set_env(&env, &envsize, 1115 ocp, cp + 1); 1116 } 1117 free(ocp); 1118 } 1119 } 1120 1121 /* read $HOME/.ssh/environment. */ 1122 if (options.permit_user_env) { 1123 snprintf(buf, sizeof buf, "%.200s/%s/environment", 1124 pw->pw_dir, _PATH_SSH_USER_DIR); 1125 read_environment_file(&env, &envsize, buf, 1126 options.permit_user_env_allowlist); 1127 } 1128 1129 #ifdef USE_PAM 1130 /* 1131 * Pull in any environment variables that may have 1132 * been set by PAM. 1133 */ 1134 if (options.use_pam) { 1135 char **p; 1136 1137 /* 1138 * Don't allow PAM-internal env vars to leak 1139 * back into the session environment. 1140 */ 1141 #define PAM_ENV_DENYLIST "SSH_AUTH_INFO*,SSH_CONNECTION*" 1142 p = fetch_pam_child_environment(); 1143 copy_environment_denylist(p, &env, &envsize, 1144 PAM_ENV_DENYLIST); 1145 free_pam_environment(p); 1146 1147 p = fetch_pam_environment(); 1148 copy_environment_denylist(p, &env, &envsize, 1149 PAM_ENV_DENYLIST); 1150 free_pam_environment(p); 1151 } 1152 #endif /* USE_PAM */ 1153 1154 /* Environment specified by admin */ 1155 for (i = 0; i < options.num_setenv; i++) { 1156 cp = xstrdup(options.setenv[i]); 1157 if ((value = strchr(cp, '=')) == NULL) { 1158 /* shouldn't happen; vars are checked in servconf.c */ 1159 fatal("Invalid config SetEnv: %s", options.setenv[i]); 1160 } 1161 *value++ = '\0'; 1162 child_set_env(&env, &envsize, cp, value); 1163 } 1164 1165 /* SSH_CLIENT deprecated */ 1166 snprintf(buf, sizeof buf, "%.50s %d %d", 1167 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 1168 ssh_local_port(ssh)); 1169 child_set_env(&env, &envsize, "SSH_CLIENT", buf); 1170 1171 laddr = get_local_ipaddr(ssh_packet_get_connection_in(ssh)); 1172 snprintf(buf, sizeof buf, "%.50s %d %.50s %d", 1173 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 1174 laddr, ssh_local_port(ssh)); 1175 free(laddr); 1176 child_set_env(&env, &envsize, "SSH_CONNECTION", buf); 1177 1178 if (tun_fwd_ifnames != NULL) 1179 child_set_env(&env, &envsize, "SSH_TUNNEL", tun_fwd_ifnames); 1180 if (auth_info_file != NULL) 1181 child_set_env(&env, &envsize, "SSH_USER_AUTH", auth_info_file); 1182 if (s->ttyfd != -1) 1183 child_set_env(&env, &envsize, "SSH_TTY", s->tty); 1184 if (original_command) 1185 child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND", 1186 original_command); 1187 1188 if (debug_flag) { 1189 /* dump the environment */ 1190 fprintf(stderr, "Environment:\n"); 1191 for (i = 0; env[i]; i++) 1192 fprintf(stderr, " %.200s\n", env[i]); 1193 } 1194 return env; 1195 } 1196 1197 /* 1198 * Run $HOME/.ssh/rc, /etc/ssh/sshrc, or xauth (whichever is found 1199 * first in this order). 1200 */ 1201 static void 1202 do_rc_files(struct ssh *ssh, Session *s, const char *shell) 1203 { 1204 FILE *f = NULL; 1205 char *cmd = NULL, *user_rc = NULL; 1206 int do_xauth; 1207 struct stat st; 1208 1209 do_xauth = 1210 s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL; 1211 xasprintf(&user_rc, "%s/%s", s->pw->pw_dir, _PATH_SSH_USER_RC); 1212 1213 /* ignore _PATH_SSH_USER_RC for subsystems and admin forced commands */ 1214 if (!s->is_subsystem && options.adm_forced_command == NULL && 1215 auth_opts->permit_user_rc && options.permit_user_rc && 1216 stat(user_rc, &st) >= 0) { 1217 if (xasprintf(&cmd, "%s -c '%s %s'", shell, _PATH_BSHELL, 1218 user_rc) == -1) 1219 fatal_f("xasprintf: %s", strerror(errno)); 1220 if (debug_flag) 1221 fprintf(stderr, "Running %s\n", cmd); 1222 f = popen(cmd, "w"); 1223 if (f) { 1224 if (do_xauth) 1225 fprintf(f, "%s %s\n", s->auth_proto, 1226 s->auth_data); 1227 pclose(f); 1228 } else 1229 fprintf(stderr, "Could not run %s\n", 1230 user_rc); 1231 } else if (stat(_PATH_SSH_SYSTEM_RC, &st) >= 0) { 1232 if (debug_flag) 1233 fprintf(stderr, "Running %s %s\n", _PATH_BSHELL, 1234 _PATH_SSH_SYSTEM_RC); 1235 f = popen(_PATH_BSHELL " " _PATH_SSH_SYSTEM_RC, "w"); 1236 if (f) { 1237 if (do_xauth) 1238 fprintf(f, "%s %s\n", s->auth_proto, 1239 s->auth_data); 1240 pclose(f); 1241 } else 1242 fprintf(stderr, "Could not run %s\n", 1243 _PATH_SSH_SYSTEM_RC); 1244 } else if (do_xauth && options.xauth_location != NULL) { 1245 /* Add authority data to .Xauthority if appropriate. */ 1246 if (debug_flag) { 1247 fprintf(stderr, 1248 "Running %.500s remove %.100s\n", 1249 options.xauth_location, s->auth_display); 1250 fprintf(stderr, 1251 "%.500s add %.100s %.100s %.100s\n", 1252 options.xauth_location, s->auth_display, 1253 s->auth_proto, s->auth_data); 1254 } 1255 if (xasprintf(&cmd, "%s -q -", options.xauth_location) == -1) 1256 fatal_f("xasprintf: %s", strerror(errno)); 1257 f = popen(cmd, "w"); 1258 if (f) { 1259 fprintf(f, "remove %s\n", 1260 s->auth_display); 1261 fprintf(f, "add %s %s %s\n", 1262 s->auth_display, s->auth_proto, 1263 s->auth_data); 1264 pclose(f); 1265 } else { 1266 fprintf(stderr, "Could not run %s\n", 1267 cmd); 1268 } 1269 } 1270 free(cmd); 1271 free(user_rc); 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 return; 1292 1293 /* /etc/nologin exists. Print its contents if we can and exit. */ 1294 logit("User %.100s not allowed because %s exists", pw->pw_name, nl); 1295 if ((f = fopen(nl, "r")) != NULL) { 1296 while (fgets(buf, sizeof(buf), f)) 1297 fputs(buf, stderr); 1298 fclose(f); 1299 } 1300 exit(254); 1301 } 1302 1303 /* 1304 * Chroot into a directory after checking it for safety: all path components 1305 * must be root-owned directories with strict permissions. 1306 */ 1307 static void 1308 safely_chroot(const char *path, uid_t uid) 1309 { 1310 const char *cp; 1311 char component[PATH_MAX]; 1312 struct stat st; 1313 1314 if (!path_absolute(path)) 1315 fatal("chroot path does not begin at root"); 1316 if (strlen(path) >= sizeof(component)) 1317 fatal("chroot path too long"); 1318 1319 /* 1320 * Descend the path, checking that each component is a 1321 * root-owned directory with strict permissions. 1322 */ 1323 for (cp = path; cp != NULL;) { 1324 if ((cp = strchr(cp, '/')) == NULL) 1325 strlcpy(component, path, sizeof(component)); 1326 else { 1327 cp++; 1328 memcpy(component, path, cp - path); 1329 component[cp - path] = '\0'; 1330 } 1331 1332 debug3_f("checking '%s'", component); 1333 1334 if (stat(component, &st) != 0) 1335 fatal_f("stat(\"%s\"): %s", 1336 component, strerror(errno)); 1337 if (st.st_uid != 0 || (st.st_mode & 022) != 0) 1338 fatal("bad ownership or modes for chroot " 1339 "directory %s\"%s\"", 1340 cp == NULL ? "" : "component ", component); 1341 if (!S_ISDIR(st.st_mode)) 1342 fatal("chroot path %s\"%s\" is not a directory", 1343 cp == NULL ? "" : "component ", component); 1344 1345 } 1346 1347 if (chdir(path) == -1) 1348 fatal("Unable to chdir to chroot path \"%s\": " 1349 "%s", path, strerror(errno)); 1350 if (chroot(path) == -1) 1351 fatal("chroot(\"%s\"): %s", path, strerror(errno)); 1352 if (chdir("/") == -1) 1353 fatal_f("chdir(/) after chroot: %s", strerror(errno)); 1354 verbose("Changed root directory to \"%s\"", path); 1355 } 1356 1357 /* Set login name, uid, gid, and groups. */ 1358 void 1359 do_setusercontext(struct passwd *pw) 1360 { 1361 char uidstr[32], *chroot_path, *tmp; 1362 1363 platform_setusercontext(pw); 1364 1365 if (platform_privileged_uidswap()) { 1366 #ifdef HAVE_LOGIN_CAP 1367 if (setusercontext(lc, pw, pw->pw_uid, 1368 (LOGIN_SETALL & ~(LOGIN_SETPATH|LOGIN_SETUSER))) < 0) { 1369 perror("unable to set user context"); 1370 exit(1); 1371 } 1372 #else 1373 if (setlogin(pw->pw_name) < 0) 1374 error("setlogin failed: %s", strerror(errno)); 1375 if (setgid(pw->pw_gid) < 0) { 1376 perror("setgid"); 1377 exit(1); 1378 } 1379 /* Initialize the group list. */ 1380 if (initgroups(pw->pw_name, pw->pw_gid) < 0) { 1381 perror("initgroups"); 1382 exit(1); 1383 } 1384 endgrent(); 1385 #endif 1386 1387 platform_setusercontext_post_groups(pw); 1388 1389 if (!in_chroot && options.chroot_directory != NULL && 1390 strcasecmp(options.chroot_directory, "none") != 0) { 1391 tmp = tilde_expand_filename(options.chroot_directory, 1392 pw->pw_uid); 1393 snprintf(uidstr, sizeof(uidstr), "%llu", 1394 (unsigned long long)pw->pw_uid); 1395 chroot_path = percent_expand(tmp, "h", pw->pw_dir, 1396 "u", pw->pw_name, "U", uidstr, (char *)NULL); 1397 safely_chroot(chroot_path, pw->pw_uid); 1398 free(tmp); 1399 free(chroot_path); 1400 /* Make sure we don't attempt to chroot again */ 1401 free(options.chroot_directory); 1402 options.chroot_directory = NULL; 1403 in_chroot = 1; 1404 } 1405 1406 #ifdef HAVE_LOGIN_CAP 1407 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUSER) < 0) { 1408 perror("unable to set user context (setuser)"); 1409 exit(1); 1410 } 1411 /* 1412 * FreeBSD's setusercontext() will not apply the user's 1413 * own umask setting unless running with the user's UID. 1414 */ 1415 (void) setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUMASK); 1416 #else 1417 # ifdef USE_LIBIAF 1418 /* 1419 * In a chroot environment, the set_id() will always fail; 1420 * typically because of the lack of necessary authentication 1421 * services and runtime such as ./usr/lib/libiaf.so, 1422 * ./usr/lib/libpam.so.1, and ./etc/passwd We skip it in the 1423 * internal sftp chroot case. We'll lose auditing and ACLs but 1424 * permanently_set_uid will take care of the rest. 1425 */ 1426 if (!in_chroot && set_id(pw->pw_name) != 0) 1427 fatal("set_id(%s) Failed", pw->pw_name); 1428 # endif /* USE_LIBIAF */ 1429 /* Permanently switch to the desired uid. */ 1430 permanently_set_uid(pw); 1431 #endif 1432 } else if (options.chroot_directory != NULL && 1433 strcasecmp(options.chroot_directory, "none") != 0) { 1434 fatal("server lacks privileges to chroot to ChrootDirectory"); 1435 } 1436 1437 if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) 1438 fatal("Failed to set uids to %u.", (u_int) pw->pw_uid); 1439 } 1440 1441 static void 1442 do_pwchange(Session *s) 1443 { 1444 fflush(NULL); 1445 fprintf(stderr, "WARNING: Your password has expired.\n"); 1446 if (s->ttyfd != -1) { 1447 fprintf(stderr, 1448 "You must change your password now and login again!\n"); 1449 #ifdef WITH_SELINUX 1450 setexeccon(NULL); 1451 #endif 1452 #ifdef PASSWD_NEEDS_USERNAME 1453 execl(_PATH_PASSWD_PROG, "passwd", s->pw->pw_name, 1454 (char *)NULL); 1455 #else 1456 execl(_PATH_PASSWD_PROG, "passwd", (char *)NULL); 1457 #endif 1458 perror("passwd"); 1459 } else { 1460 fprintf(stderr, 1461 "Password change required but no TTY available.\n"); 1462 } 1463 exit(1); 1464 } 1465 1466 static void 1467 child_close_fds(struct ssh *ssh) 1468 { 1469 extern int auth_sock; 1470 1471 if (auth_sock != -1) { 1472 close(auth_sock); 1473 auth_sock = -1; 1474 } 1475 1476 if (ssh_packet_get_connection_in(ssh) == 1477 ssh_packet_get_connection_out(ssh)) 1478 close(ssh_packet_get_connection_in(ssh)); 1479 else { 1480 close(ssh_packet_get_connection_in(ssh)); 1481 close(ssh_packet_get_connection_out(ssh)); 1482 } 1483 /* 1484 * Close all descriptors related to channels. They will still remain 1485 * open in the parent. 1486 */ 1487 /* XXX better use close-on-exec? -markus */ 1488 channel_close_all(ssh); 1489 1490 /* 1491 * Close any extra file descriptors. Note that there may still be 1492 * descriptors left by system functions. They will be closed later. 1493 */ 1494 endpwent(); 1495 1496 /* Stop directing logs to a high-numbered fd before we close it */ 1497 log_redirect_stderr_to(NULL); 1498 1499 /* 1500 * Close any extra open file descriptors so that we don't have them 1501 * hanging around in clients. Note that we want to do this after 1502 * initgroups, because at least on Solaris 2.3 it leaves file 1503 * descriptors open. 1504 */ 1505 closefrom(STDERR_FILENO + 1); 1506 } 1507 1508 /* 1509 * Performs common processing for the child, such as setting up the 1510 * environment, closing extra file descriptors, setting the user and group 1511 * ids, and executing the command or shell. 1512 */ 1513 #define ARGV_MAX 10 1514 void 1515 do_child(struct ssh *ssh, Session *s, const char *command) 1516 { 1517 extern char **environ; 1518 char **env, *argv[ARGV_MAX], remote_id[512]; 1519 const char *shell, *shell0; 1520 struct passwd *pw = s->pw; 1521 int r = 0; 1522 1523 sshpkt_fmt_connection_id(ssh, remote_id, sizeof(remote_id)); 1524 1525 /* remove hostkey from the child's memory */ 1526 destroy_sensitive_data(); 1527 ssh_packet_clear_keys(ssh); 1528 1529 /* Force a password change */ 1530 if (s->authctxt->force_pwchange) { 1531 do_setusercontext(pw); 1532 child_close_fds(ssh); 1533 do_pwchange(s); 1534 exit(1); 1535 } 1536 1537 /* 1538 * Login(1) does this as well, and it needs uid 0 for the "-h" 1539 * switch, so we let login(1) to this for us. 1540 */ 1541 #ifdef HAVE_OSF_SIA 1542 session_setup_sia(pw, s->ttyfd == -1 ? NULL : s->tty); 1543 if (!check_quietlogin(s, command)) 1544 do_motd(); 1545 #else /* HAVE_OSF_SIA */ 1546 /* When PAM is enabled we rely on it to do the nologin check */ 1547 if (!options.use_pam) 1548 do_nologin(pw); 1549 do_setusercontext(pw); 1550 /* 1551 * PAM session modules in do_setusercontext may have 1552 * generated messages, so if this in an interactive 1553 * login then display them too. 1554 */ 1555 if (!check_quietlogin(s, command)) 1556 display_loginmsg(); 1557 #endif /* HAVE_OSF_SIA */ 1558 1559 #ifdef USE_PAM 1560 if (options.use_pam && !is_pam_session_open()) { 1561 debug3("PAM session not opened, exiting"); 1562 display_loginmsg(); 1563 exit(254); 1564 } 1565 #endif 1566 1567 /* 1568 * Get the shell from the password data. An empty shell field is 1569 * legal, and means /bin/sh. 1570 */ 1571 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; 1572 1573 /* 1574 * Make sure $SHELL points to the shell from the password file, 1575 * even if shell is overridden from login.conf 1576 */ 1577 env = do_setup_env(ssh, s, shell); 1578 1579 #ifdef HAVE_LOGIN_CAP 1580 shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell); 1581 #endif 1582 1583 /* 1584 * Close the connection descriptors; note that this is the child, and 1585 * the server will still have the socket open, and it is important 1586 * that we do not shutdown it. Note that the descriptors cannot be 1587 * closed before building the environment, as we call 1588 * ssh_remote_ipaddr there. 1589 */ 1590 child_close_fds(ssh); 1591 1592 /* 1593 * Must take new environment into use so that .ssh/rc, 1594 * /etc/ssh/sshrc and xauth are run in the proper environment. 1595 */ 1596 environ = env; 1597 1598 #if defined(KRB5) && defined(USE_AFS) 1599 /* 1600 * At this point, we check to see if AFS is active and if we have 1601 * a valid Kerberos 5 TGT. If so, it seems like a good idea to see 1602 * if we can (and need to) extend the ticket into an AFS token. If 1603 * we don't do this, we run into potential problems if the user's 1604 * home directory is in AFS and it's not world-readable. 1605 */ 1606 1607 if (options.kerberos_get_afs_token && k_hasafs() && 1608 (s->authctxt->krb5_ctx != NULL)) { 1609 char cell[64]; 1610 1611 debug("Getting AFS token"); 1612 1613 k_setpag(); 1614 1615 if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0) 1616 krb5_afslog(s->authctxt->krb5_ctx, 1617 s->authctxt->krb5_fwd_ccache, cell, NULL); 1618 1619 krb5_afslog_home(s->authctxt->krb5_ctx, 1620 s->authctxt->krb5_fwd_ccache, NULL, NULL, pw->pw_dir); 1621 } 1622 #endif 1623 1624 /* Change current directory to the user's home directory. */ 1625 if (chdir(pw->pw_dir) == -1) { 1626 /* Suppress missing homedir warning for chroot case */ 1627 #ifdef HAVE_LOGIN_CAP 1628 r = login_getcapbool(lc, "requirehome", 0); 1629 #endif 1630 if (r || !in_chroot) { 1631 fprintf(stderr, "Could not chdir to home " 1632 "directory %s: %s\n", pw->pw_dir, 1633 strerror(errno)); 1634 } 1635 if (r) 1636 exit(1); 1637 } 1638 1639 closefrom(STDERR_FILENO + 1); 1640 1641 do_rc_files(ssh, s, shell); 1642 1643 /* restore SIGPIPE for child */ 1644 ssh_signal(SIGPIPE, SIG_DFL); 1645 1646 if (s->is_subsystem == SUBSYSTEM_INT_SFTP_ERROR) { 1647 error("Connection from %s: refusing non-sftp session", 1648 remote_id); 1649 printf("This service allows sftp connections only.\n"); 1650 fflush(NULL); 1651 exit(1); 1652 } else if (s->is_subsystem == SUBSYSTEM_INT_SFTP) { 1653 extern int optind, optreset; 1654 int i; 1655 char *p, *args; 1656 1657 setproctitle("%s@%s", s->pw->pw_name, INTERNAL_SFTP_NAME); 1658 args = xstrdup(command ? command : "sftp-server"); 1659 for (i = 0, (p = strtok(args, " ")); p; (p = strtok(NULL, " "))) 1660 if (i < ARGV_MAX - 1) 1661 argv[i++] = p; 1662 argv[i] = NULL; 1663 optind = optreset = 1; 1664 __progname = argv[0]; 1665 #ifdef WITH_SELINUX 1666 ssh_selinux_change_context("sftpd_t"); 1667 #endif 1668 exit(sftp_server_main(i, argv, s->pw)); 1669 } 1670 1671 fflush(NULL); 1672 1673 /* Get the last component of the shell name. */ 1674 if ((shell0 = strrchr(shell, '/')) != NULL) 1675 shell0++; 1676 else 1677 shell0 = shell; 1678 1679 /* 1680 * If we have no command, execute the shell. In this case, the shell 1681 * name to be passed in argv[0] is preceded by '-' to indicate that 1682 * this is a login shell. 1683 */ 1684 if (!command) { 1685 char argv0[256]; 1686 1687 /* Start the shell. Set initial character to '-'. */ 1688 argv0[0] = '-'; 1689 1690 if (strlcpy(argv0 + 1, shell0, sizeof(argv0) - 1) 1691 >= sizeof(argv0) - 1) { 1692 errno = EINVAL; 1693 perror(shell); 1694 exit(1); 1695 } 1696 1697 /* Execute the shell. */ 1698 argv[0] = argv0; 1699 argv[1] = NULL; 1700 execve(shell, argv, env); 1701 1702 /* Executing the shell failed. */ 1703 perror(shell); 1704 exit(1); 1705 } 1706 /* 1707 * Execute the command using the user's shell. This uses the -c 1708 * option to execute the command. 1709 */ 1710 argv[0] = (char *) shell0; 1711 argv[1] = "-c"; 1712 argv[2] = (char *) command; 1713 argv[3] = NULL; 1714 execve(shell, argv, env); 1715 perror(shell); 1716 exit(1); 1717 } 1718 1719 void 1720 session_unused(int id) 1721 { 1722 debug3_f("session id %d unused", id); 1723 if (id >= options.max_sessions || 1724 id >= sessions_nalloc) { 1725 fatal_f("insane session id %d (max %d nalloc %d)", 1726 id, options.max_sessions, sessions_nalloc); 1727 } 1728 memset(&sessions[id], 0, sizeof(*sessions)); 1729 sessions[id].self = id; 1730 sessions[id].used = 0; 1731 sessions[id].chanid = -1; 1732 sessions[id].ptyfd = -1; 1733 sessions[id].ttyfd = -1; 1734 sessions[id].ptymaster = -1; 1735 sessions[id].x11_chanids = NULL; 1736 sessions[id].next_unused = sessions_first_unused; 1737 sessions_first_unused = id; 1738 } 1739 1740 Session * 1741 session_new(void) 1742 { 1743 Session *s, *tmp; 1744 1745 if (sessions_first_unused == -1) { 1746 if (sessions_nalloc >= options.max_sessions) 1747 return NULL; 1748 debug2_f("allocate (allocated %d max %d)", 1749 sessions_nalloc, options.max_sessions); 1750 tmp = xrecallocarray(sessions, sessions_nalloc, 1751 sessions_nalloc + 1, sizeof(*sessions)); 1752 if (tmp == NULL) { 1753 error_f("cannot allocate %d sessions", 1754 sessions_nalloc + 1); 1755 return NULL; 1756 } 1757 sessions = tmp; 1758 session_unused(sessions_nalloc++); 1759 } 1760 1761 if (sessions_first_unused >= sessions_nalloc || 1762 sessions_first_unused < 0) { 1763 fatal_f("insane first_unused %d max %d nalloc %d", 1764 sessions_first_unused, options.max_sessions, 1765 sessions_nalloc); 1766 } 1767 1768 s = &sessions[sessions_first_unused]; 1769 if (s->used) 1770 fatal_f("session %d already used", sessions_first_unused); 1771 sessions_first_unused = s->next_unused; 1772 s->used = 1; 1773 s->next_unused = -1; 1774 debug("session_new: session %d", s->self); 1775 1776 return s; 1777 } 1778 1779 static void 1780 session_dump(void) 1781 { 1782 int i; 1783 for (i = 0; i < sessions_nalloc; i++) { 1784 Session *s = &sessions[i]; 1785 1786 debug("dump: used %d next_unused %d session %d " 1787 "channel %d pid %ld", 1788 s->used, 1789 s->next_unused, 1790 s->self, 1791 s->chanid, 1792 (long)s->pid); 1793 } 1794 } 1795 1796 int 1797 session_open(Authctxt *authctxt, int chanid) 1798 { 1799 Session *s = session_new(); 1800 debug("session_open: channel %d", chanid); 1801 if (s == NULL) { 1802 error("no more sessions"); 1803 return 0; 1804 } 1805 s->authctxt = authctxt; 1806 s->pw = authctxt->pw; 1807 if (s->pw == NULL || !authctxt->valid) 1808 fatal("no user for session %d", s->self); 1809 debug("session_open: session %d: link with channel %d", s->self, chanid); 1810 s->chanid = chanid; 1811 return 1; 1812 } 1813 1814 Session * 1815 session_by_tty(char *tty) 1816 { 1817 int i; 1818 for (i = 0; i < sessions_nalloc; i++) { 1819 Session *s = &sessions[i]; 1820 if (s->used && s->ttyfd != -1 && strcmp(s->tty, tty) == 0) { 1821 debug("session_by_tty: session %d tty %s", i, tty); 1822 return s; 1823 } 1824 } 1825 debug("session_by_tty: unknown tty %.100s", tty); 1826 session_dump(); 1827 return NULL; 1828 } 1829 1830 static Session * 1831 session_by_channel(int id) 1832 { 1833 int i; 1834 for (i = 0; i < sessions_nalloc; i++) { 1835 Session *s = &sessions[i]; 1836 if (s->used && s->chanid == id) { 1837 debug("session_by_channel: session %d channel %d", 1838 i, id); 1839 return s; 1840 } 1841 } 1842 debug("session_by_channel: unknown channel %d", id); 1843 session_dump(); 1844 return NULL; 1845 } 1846 1847 static Session * 1848 session_by_x11_channel(int id) 1849 { 1850 int i, j; 1851 1852 for (i = 0; i < sessions_nalloc; i++) { 1853 Session *s = &sessions[i]; 1854 1855 if (s->x11_chanids == NULL || !s->used) 1856 continue; 1857 for (j = 0; s->x11_chanids[j] != -1; j++) { 1858 if (s->x11_chanids[j] == id) { 1859 debug("session_by_x11_channel: session %d " 1860 "channel %d", s->self, id); 1861 return s; 1862 } 1863 } 1864 } 1865 debug("session_by_x11_channel: unknown channel %d", id); 1866 session_dump(); 1867 return NULL; 1868 } 1869 1870 static Session * 1871 session_by_pid(pid_t pid) 1872 { 1873 int i; 1874 debug("session_by_pid: pid %ld", (long)pid); 1875 for (i = 0; i < sessions_nalloc; i++) { 1876 Session *s = &sessions[i]; 1877 if (s->used && s->pid == pid) 1878 return s; 1879 } 1880 error("session_by_pid: unknown pid %ld", (long)pid); 1881 session_dump(); 1882 return NULL; 1883 } 1884 1885 static int 1886 session_window_change_req(struct ssh *ssh, Session *s) 1887 { 1888 int r; 1889 1890 if ((r = sshpkt_get_u32(ssh, &s->col)) != 0 || 1891 (r = sshpkt_get_u32(ssh, &s->row)) != 0 || 1892 (r = sshpkt_get_u32(ssh, &s->xpixel)) != 0 || 1893 (r = sshpkt_get_u32(ssh, &s->ypixel)) != 0 || 1894 (r = sshpkt_get_end(ssh)) != 0) 1895 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 1896 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 1897 return 1; 1898 } 1899 1900 static int 1901 session_pty_req(struct ssh *ssh, Session *s) 1902 { 1903 int r; 1904 1905 if (!auth_opts->permit_pty_flag || !options.permit_tty) { 1906 debug("Allocating a pty not permitted for this connection."); 1907 return 0; 1908 } 1909 if (s->ttyfd != -1) { 1910 ssh_packet_disconnect(ssh, "Protocol error: you already have a pty."); 1911 return 0; 1912 } 1913 1914 if ((r = sshpkt_get_cstring(ssh, &s->term, NULL)) != 0 || 1915 (r = sshpkt_get_u32(ssh, &s->col)) != 0 || 1916 (r = sshpkt_get_u32(ssh, &s->row)) != 0 || 1917 (r = sshpkt_get_u32(ssh, &s->xpixel)) != 0 || 1918 (r = sshpkt_get_u32(ssh, &s->ypixel)) != 0) 1919 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 1920 1921 if (strcmp(s->term, "") == 0) { 1922 free(s->term); 1923 s->term = NULL; 1924 } 1925 1926 /* Allocate a pty and open it. */ 1927 debug("Allocating pty."); 1928 if (!PRIVSEP(pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, 1929 sizeof(s->tty)))) { 1930 free(s->term); 1931 s->term = NULL; 1932 s->ptyfd = -1; 1933 s->ttyfd = -1; 1934 error("session_pty_req: session %d alloc failed", s->self); 1935 return 0; 1936 } 1937 debug("session_pty_req: session %d alloc %s", s->self, s->tty); 1938 1939 ssh_tty_parse_modes(ssh, s->ttyfd); 1940 1941 if ((r = sshpkt_get_end(ssh)) != 0) 1942 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 1943 1944 if (!use_privsep) 1945 pty_setowner(s->pw, s->tty); 1946 1947 /* Set window size from the packet. */ 1948 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 1949 1950 session_proctitle(s); 1951 return 1; 1952 } 1953 1954 static int 1955 session_subsystem_req(struct ssh *ssh, Session *s) 1956 { 1957 struct stat st; 1958 int r, success = 0; 1959 char *prog, *cmd; 1960 u_int i; 1961 1962 if ((r = sshpkt_get_cstring(ssh, &s->subsys, NULL)) != 0 || 1963 (r = sshpkt_get_end(ssh)) != 0) 1964 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 1965 debug2("subsystem request for %.100s by user %s", s->subsys, 1966 s->pw->pw_name); 1967 1968 for (i = 0; i < options.num_subsystems; i++) { 1969 if (strcmp(s->subsys, options.subsystem_name[i]) == 0) { 1970 prog = options.subsystem_command[i]; 1971 cmd = options.subsystem_args[i]; 1972 if (strcmp(INTERNAL_SFTP_NAME, prog) == 0) { 1973 s->is_subsystem = SUBSYSTEM_INT_SFTP; 1974 debug("subsystem: %s", prog); 1975 } else { 1976 if (stat(prog, &st) == -1) 1977 debug("subsystem: cannot stat %s: %s", 1978 prog, strerror(errno)); 1979 s->is_subsystem = SUBSYSTEM_EXT; 1980 debug("subsystem: exec() %s", cmd); 1981 } 1982 success = do_exec(ssh, s, cmd) == 0; 1983 break; 1984 } 1985 } 1986 1987 if (!success) 1988 logit("subsystem request for %.100s by user %s failed, " 1989 "subsystem not found", s->subsys, s->pw->pw_name); 1990 1991 return success; 1992 } 1993 1994 static int 1995 session_x11_req(struct ssh *ssh, Session *s) 1996 { 1997 int r, success; 1998 u_char single_connection = 0; 1999 2000 if (s->auth_proto != NULL || s->auth_data != NULL) { 2001 error("session_x11_req: session %d: " 2002 "x11 forwarding already active", s->self); 2003 return 0; 2004 } 2005 if ((r = sshpkt_get_u8(ssh, &single_connection)) != 0 || 2006 (r = sshpkt_get_cstring(ssh, &s->auth_proto, NULL)) != 0 || 2007 (r = sshpkt_get_cstring(ssh, &s->auth_data, NULL)) != 0 || 2008 (r = sshpkt_get_u32(ssh, &s->screen)) != 0 || 2009 (r = sshpkt_get_end(ssh)) != 0) 2010 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 2011 2012 s->single_connection = single_connection; 2013 2014 if (xauth_valid_string(s->auth_proto) && 2015 xauth_valid_string(s->auth_data)) 2016 success = session_setup_x11fwd(ssh, s); 2017 else { 2018 success = 0; 2019 error("Invalid X11 forwarding data"); 2020 } 2021 if (!success) { 2022 free(s->auth_proto); 2023 free(s->auth_data); 2024 s->auth_proto = NULL; 2025 s->auth_data = NULL; 2026 } 2027 return success; 2028 } 2029 2030 static int 2031 session_shell_req(struct ssh *ssh, Session *s) 2032 { 2033 int r; 2034 2035 if ((r = sshpkt_get_end(ssh)) != 0) 2036 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 2037 return do_exec(ssh, s, NULL) == 0; 2038 } 2039 2040 static int 2041 session_exec_req(struct ssh *ssh, Session *s) 2042 { 2043 u_int success; 2044 int r; 2045 char *command = NULL; 2046 2047 if ((r = sshpkt_get_cstring(ssh, &command, NULL)) != 0 || 2048 (r = sshpkt_get_end(ssh)) != 0) 2049 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 2050 2051 success = do_exec(ssh, s, command) == 0; 2052 free(command); 2053 return success; 2054 } 2055 2056 static int 2057 session_break_req(struct ssh *ssh, Session *s) 2058 { 2059 int r; 2060 2061 if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* ignore */ 2062 (r = sshpkt_get_end(ssh)) != 0) 2063 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 2064 2065 if (s->ptymaster == -1 || tcsendbreak(s->ptymaster, 0) == -1) 2066 return 0; 2067 return 1; 2068 } 2069 2070 static int 2071 session_env_req(struct ssh *ssh, Session *s) 2072 { 2073 char *name, *val; 2074 u_int i; 2075 int r; 2076 2077 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 || 2078 (r = sshpkt_get_cstring(ssh, &val, NULL)) != 0 || 2079 (r = sshpkt_get_end(ssh)) != 0) 2080 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 2081 2082 /* Don't set too many environment variables */ 2083 if (s->num_env > 128) { 2084 debug2("Ignoring env request %s: too many env vars", name); 2085 goto fail; 2086 } 2087 2088 for (i = 0; i < options.num_accept_env; i++) { 2089 if (match_pattern(name, options.accept_env[i])) { 2090 debug2("Setting env %d: %s=%s", s->num_env, name, val); 2091 s->env = xrecallocarray(s->env, s->num_env, 2092 s->num_env + 1, sizeof(*s->env)); 2093 s->env[s->num_env].name = name; 2094 s->env[s->num_env].val = val; 2095 s->num_env++; 2096 return (1); 2097 } 2098 } 2099 debug2("Ignoring env request %s: disallowed name", name); 2100 2101 fail: 2102 free(name); 2103 free(val); 2104 return (0); 2105 } 2106 2107 /* 2108 * Conversion of signals from ssh channel request names. 2109 * Subset of signals from RFC 4254 section 6.10C, with SIGINFO as 2110 * local extension. 2111 */ 2112 static int 2113 name2sig(char *name) 2114 { 2115 #define SSH_SIG(x) if (strcmp(name, #x) == 0) return SIG ## x 2116 SSH_SIG(HUP); 2117 SSH_SIG(INT); 2118 SSH_SIG(KILL); 2119 SSH_SIG(QUIT); 2120 SSH_SIG(TERM); 2121 SSH_SIG(USR1); 2122 SSH_SIG(USR2); 2123 #undef SSH_SIG 2124 #ifdef SIGINFO 2125 if (strcmp(name, "INFO@openssh.com") == 0) 2126 return SIGINFO; 2127 #endif 2128 return -1; 2129 } 2130 2131 static int 2132 session_signal_req(struct ssh *ssh, Session *s) 2133 { 2134 char *signame = NULL; 2135 int r, sig, success = 0; 2136 2137 if ((r = sshpkt_get_cstring(ssh, &signame, NULL)) != 0 || 2138 (r = sshpkt_get_end(ssh)) != 0) { 2139 error_fr(r, "parse"); 2140 goto out; 2141 } 2142 if ((sig = name2sig(signame)) == -1) { 2143 error_f("unsupported signal \"%s\"", signame); 2144 goto out; 2145 } 2146 if (s->pid <= 0) { 2147 error_f("no pid for session %d", s->self); 2148 goto out; 2149 } 2150 if (s->forced || s->is_subsystem) { 2151 error_f("refusing to send signal %s to %s session", 2152 signame, s->forced ? "forced-command" : "subsystem"); 2153 goto out; 2154 } 2155 if (!use_privsep || mm_is_monitor()) { 2156 error_f("session signalling requires privilege separation"); 2157 goto out; 2158 } 2159 2160 debug_f("signal %s, killpg(%ld, %d)", signame, (long)s->pid, sig); 2161 temporarily_use_uid(s->pw); 2162 r = killpg(s->pid, sig); 2163 restore_uid(); 2164 if (r != 0) { 2165 error_f("killpg(%ld, %d): %s", (long)s->pid, 2166 sig, strerror(errno)); 2167 goto out; 2168 } 2169 2170 /* success */ 2171 success = 1; 2172 out: 2173 free(signame); 2174 return success; 2175 } 2176 2177 static int 2178 session_auth_agent_req(struct ssh *ssh, Session *s) 2179 { 2180 static int called = 0; 2181 int r; 2182 2183 if ((r = sshpkt_get_end(ssh)) != 0) 2184 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 2185 if (!auth_opts->permit_agent_forwarding_flag || 2186 !options.allow_agent_forwarding) { 2187 debug_f("agent forwarding disabled"); 2188 return 0; 2189 } 2190 if (called) { 2191 return 0; 2192 } else { 2193 called = 1; 2194 return auth_input_request_forwarding(ssh, s->pw); 2195 } 2196 } 2197 2198 int 2199 session_input_channel_req(struct ssh *ssh, Channel *c, const char *rtype) 2200 { 2201 int success = 0; 2202 Session *s; 2203 2204 if ((s = session_by_channel(c->self)) == NULL) { 2205 logit_f("no session %d req %.100s", c->self, rtype); 2206 return 0; 2207 } 2208 debug_f("session %d req %s", s->self, rtype); 2209 2210 /* 2211 * a session is in LARVAL state until a shell, a command 2212 * or a subsystem is executed 2213 */ 2214 if (c->type == SSH_CHANNEL_LARVAL) { 2215 if (strcmp(rtype, "shell") == 0) { 2216 success = session_shell_req(ssh, s); 2217 } else if (strcmp(rtype, "exec") == 0) { 2218 success = session_exec_req(ssh, s); 2219 } else if (strcmp(rtype, "pty-req") == 0) { 2220 success = session_pty_req(ssh, s); 2221 } else if (strcmp(rtype, "x11-req") == 0) { 2222 success = session_x11_req(ssh, s); 2223 } else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) { 2224 success = session_auth_agent_req(ssh, s); 2225 } else if (strcmp(rtype, "subsystem") == 0) { 2226 success = session_subsystem_req(ssh, s); 2227 } else if (strcmp(rtype, "env") == 0) { 2228 success = session_env_req(ssh, s); 2229 } 2230 } 2231 if (strcmp(rtype, "window-change") == 0) { 2232 success = session_window_change_req(ssh, s); 2233 } else if (strcmp(rtype, "break") == 0) { 2234 success = session_break_req(ssh, s); 2235 } else if (strcmp(rtype, "signal") == 0) { 2236 success = session_signal_req(ssh, s); 2237 } 2238 2239 return success; 2240 } 2241 2242 void 2243 session_set_fds(struct ssh *ssh, Session *s, 2244 int fdin, int fdout, int fderr, int ignore_fderr, int is_tty) 2245 { 2246 /* 2247 * now that have a child and a pipe to the child, 2248 * we can activate our channel and register the fd's 2249 */ 2250 if (s->chanid == -1) 2251 fatal("no channel for session %d", s->self); 2252 channel_set_fds(ssh, s->chanid, 2253 fdout, fdin, fderr, 2254 ignore_fderr ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ, 2255 1, is_tty, CHAN_SES_WINDOW_DEFAULT); 2256 } 2257 2258 /* 2259 * Function to perform pty cleanup. Also called if we get aborted abnormally 2260 * (e.g., due to a dropped connection). 2261 */ 2262 void 2263 session_pty_cleanup2(Session *s) 2264 { 2265 if (s == NULL) { 2266 error_f("no session"); 2267 return; 2268 } 2269 if (s->ttyfd == -1) 2270 return; 2271 2272 debug_f("session %d release %s", s->self, s->tty); 2273 2274 /* Record that the user has logged out. */ 2275 if (s->pid != 0) 2276 record_logout(s->pid, s->tty, s->pw->pw_name); 2277 2278 /* Release the pseudo-tty. */ 2279 if (getuid() == 0) 2280 pty_release(s->tty); 2281 2282 /* 2283 * Close the server side of the socket pairs. We must do this after 2284 * the pty cleanup, so that another process doesn't get this pty 2285 * while we're still cleaning up. 2286 */ 2287 if (s->ptymaster != -1 && close(s->ptymaster) == -1) 2288 error("close(s->ptymaster/%d): %s", 2289 s->ptymaster, strerror(errno)); 2290 2291 /* unlink pty from session */ 2292 s->ttyfd = -1; 2293 } 2294 2295 void 2296 session_pty_cleanup(Session *s) 2297 { 2298 PRIVSEP(session_pty_cleanup2(s)); 2299 } 2300 2301 static char * 2302 sig2name(int sig) 2303 { 2304 #define SSH_SIG(x) if (sig == SIG ## x) return #x 2305 SSH_SIG(ABRT); 2306 SSH_SIG(ALRM); 2307 SSH_SIG(FPE); 2308 SSH_SIG(HUP); 2309 SSH_SIG(ILL); 2310 SSH_SIG(INT); 2311 SSH_SIG(KILL); 2312 SSH_SIG(PIPE); 2313 SSH_SIG(QUIT); 2314 SSH_SIG(SEGV); 2315 SSH_SIG(TERM); 2316 SSH_SIG(USR1); 2317 SSH_SIG(USR2); 2318 #undef SSH_SIG 2319 return "SIG@openssh.com"; 2320 } 2321 2322 static void 2323 session_close_x11(struct ssh *ssh, int id) 2324 { 2325 Channel *c; 2326 2327 if ((c = channel_by_id(ssh, id)) == NULL) { 2328 debug_f("x11 channel %d missing", id); 2329 } else { 2330 /* Detach X11 listener */ 2331 debug_f("detach x11 channel %d", id); 2332 channel_cancel_cleanup(ssh, id); 2333 if (c->ostate != CHAN_OUTPUT_CLOSED) 2334 chan_mark_dead(ssh, c); 2335 } 2336 } 2337 2338 static void 2339 session_close_single_x11(struct ssh *ssh, int id, void *arg) 2340 { 2341 Session *s; 2342 u_int i; 2343 2344 debug3_f("channel %d", id); 2345 channel_cancel_cleanup(ssh, id); 2346 if ((s = session_by_x11_channel(id)) == NULL) 2347 fatal_f("no x11 channel %d", id); 2348 for (i = 0; s->x11_chanids[i] != -1; i++) { 2349 debug_f("session %d: closing channel %d", 2350 s->self, s->x11_chanids[i]); 2351 /* 2352 * The channel "id" is already closing, but make sure we 2353 * close all of its siblings. 2354 */ 2355 if (s->x11_chanids[i] != id) 2356 session_close_x11(ssh, s->x11_chanids[i]); 2357 } 2358 free(s->x11_chanids); 2359 s->x11_chanids = NULL; 2360 free(s->display); 2361 s->display = NULL; 2362 free(s->auth_proto); 2363 s->auth_proto = NULL; 2364 free(s->auth_data); 2365 s->auth_data = NULL; 2366 free(s->auth_display); 2367 s->auth_display = NULL; 2368 } 2369 2370 static void 2371 session_exit_message(struct ssh *ssh, Session *s, int status) 2372 { 2373 Channel *c; 2374 int r; 2375 2376 if ((c = channel_lookup(ssh, s->chanid)) == NULL) 2377 fatal_f("session %d: no channel %d", s->self, s->chanid); 2378 debug_f("session %d channel %d pid %ld", 2379 s->self, s->chanid, (long)s->pid); 2380 2381 if (WIFEXITED(status)) { 2382 channel_request_start(ssh, s->chanid, "exit-status", 0); 2383 if ((r = sshpkt_put_u32(ssh, WEXITSTATUS(status))) != 0 || 2384 (r = sshpkt_send(ssh)) != 0) 2385 sshpkt_fatal(ssh, r, "%s: exit reply", __func__); 2386 } else if (WIFSIGNALED(status)) { 2387 channel_request_start(ssh, s->chanid, "exit-signal", 0); 2388 #ifndef WCOREDUMP 2389 # define WCOREDUMP(x) (0) 2390 #endif 2391 if ((r = sshpkt_put_cstring(ssh, sig2name(WTERMSIG(status)))) != 0 || 2392 (r = sshpkt_put_u8(ssh, WCOREDUMP(status)? 1 : 0)) != 0 || 2393 (r = sshpkt_put_cstring(ssh, "")) != 0 || 2394 (r = sshpkt_put_cstring(ssh, "")) != 0 || 2395 (r = sshpkt_send(ssh)) != 0) 2396 sshpkt_fatal(ssh, r, "%s: exit reply", __func__); 2397 } else { 2398 /* Some weird exit cause. Just exit. */ 2399 ssh_packet_disconnect(ssh, "wait returned status %04x.", status); 2400 } 2401 2402 /* disconnect channel */ 2403 debug_f("release channel %d", s->chanid); 2404 2405 /* 2406 * Adjust cleanup callback attachment to send close messages when 2407 * the channel gets EOF. The session will be then be closed 2408 * by session_close_by_channel when the child sessions close their fds. 2409 */ 2410 channel_register_cleanup(ssh, c->self, session_close_by_channel, 1); 2411 2412 /* 2413 * emulate a write failure with 'chan_write_failed', nobody will be 2414 * interested in data we write. 2415 * Note that we must not call 'chan_read_failed', since there could 2416 * be some more data waiting in the pipe. 2417 */ 2418 if (c->ostate != CHAN_OUTPUT_CLOSED) 2419 chan_write_failed(ssh, c); 2420 } 2421 2422 void 2423 session_close(struct ssh *ssh, Session *s) 2424 { 2425 u_int i; 2426 2427 verbose("Close session: user %s from %.200s port %d id %d", 2428 s->pw->pw_name, 2429 ssh_remote_ipaddr(ssh), 2430 ssh_remote_port(ssh), 2431 s->self); 2432 2433 if (s->ttyfd != -1) 2434 session_pty_cleanup(s); 2435 free(s->term); 2436 free(s->display); 2437 free(s->x11_chanids); 2438 free(s->auth_display); 2439 free(s->auth_data); 2440 free(s->auth_proto); 2441 free(s->subsys); 2442 if (s->env != NULL) { 2443 for (i = 0; i < s->num_env; i++) { 2444 free(s->env[i].name); 2445 free(s->env[i].val); 2446 } 2447 free(s->env); 2448 } 2449 session_proctitle(s); 2450 session_unused(s->self); 2451 } 2452 2453 void 2454 session_close_by_pid(struct ssh *ssh, pid_t pid, int status) 2455 { 2456 Session *s = session_by_pid(pid); 2457 if (s == NULL) { 2458 debug_f("no session for pid %ld", (long)pid); 2459 return; 2460 } 2461 if (s->chanid != -1) 2462 session_exit_message(ssh, s, status); 2463 if (s->ttyfd != -1) 2464 session_pty_cleanup(s); 2465 s->pid = 0; 2466 } 2467 2468 /* 2469 * this is called when a channel dies before 2470 * the session 'child' itself dies 2471 */ 2472 void 2473 session_close_by_channel(struct ssh *ssh, int id, void *arg) 2474 { 2475 Session *s = session_by_channel(id); 2476 u_int i; 2477 2478 if (s == NULL) { 2479 debug_f("no session for id %d", id); 2480 return; 2481 } 2482 debug_f("channel %d child %ld", id, (long)s->pid); 2483 if (s->pid != 0) { 2484 debug_f("channel %d: has child, ttyfd %d", id, s->ttyfd); 2485 /* 2486 * delay detach of session, but release pty, since 2487 * the fd's to the child are already closed 2488 */ 2489 if (s->ttyfd != -1) 2490 session_pty_cleanup(s); 2491 return; 2492 } 2493 /* detach by removing callback */ 2494 channel_cancel_cleanup(ssh, s->chanid); 2495 2496 /* Close any X11 listeners associated with this session */ 2497 if (s->x11_chanids != NULL) { 2498 for (i = 0; s->x11_chanids[i] != -1; i++) { 2499 session_close_x11(ssh, s->x11_chanids[i]); 2500 s->x11_chanids[i] = -1; 2501 } 2502 } 2503 2504 s->chanid = -1; 2505 session_close(ssh, s); 2506 } 2507 2508 void 2509 session_destroy_all(struct ssh *ssh, void (*closefunc)(Session *)) 2510 { 2511 int i; 2512 for (i = 0; i < sessions_nalloc; i++) { 2513 Session *s = &sessions[i]; 2514 if (s->used) { 2515 if (closefunc != NULL) 2516 closefunc(s); 2517 else 2518 session_close(ssh, s); 2519 } 2520 } 2521 } 2522 2523 static char * 2524 session_tty_list(void) 2525 { 2526 static char buf[1024]; 2527 int i; 2528 char *cp; 2529 2530 buf[0] = '\0'; 2531 for (i = 0; i < sessions_nalloc; i++) { 2532 Session *s = &sessions[i]; 2533 if (s->used && s->ttyfd != -1) { 2534 2535 if (strncmp(s->tty, "/dev/", 5) != 0) { 2536 cp = strrchr(s->tty, '/'); 2537 cp = (cp == NULL) ? s->tty : cp + 1; 2538 } else 2539 cp = s->tty + 5; 2540 2541 if (buf[0] != '\0') 2542 strlcat(buf, ",", sizeof buf); 2543 strlcat(buf, cp, sizeof buf); 2544 } 2545 } 2546 if (buf[0] == '\0') 2547 strlcpy(buf, "notty", sizeof buf); 2548 return buf; 2549 } 2550 2551 void 2552 session_proctitle(Session *s) 2553 { 2554 if (s->pw == NULL) 2555 error("no user for session %d", s->self); 2556 else 2557 setproctitle("%s@%s", s->pw->pw_name, session_tty_list()); 2558 } 2559 2560 int 2561 session_setup_x11fwd(struct ssh *ssh, Session *s) 2562 { 2563 struct stat st; 2564 char display[512], auth_display[512]; 2565 char hostname[NI_MAXHOST]; 2566 u_int i; 2567 2568 if (!auth_opts->permit_x11_forwarding_flag) { 2569 ssh_packet_send_debug(ssh, "X11 forwarding disabled by key options."); 2570 return 0; 2571 } 2572 if (!options.x11_forwarding) { 2573 debug("X11 forwarding disabled in server configuration file."); 2574 return 0; 2575 } 2576 if (options.xauth_location == NULL || 2577 (stat(options.xauth_location, &st) == -1)) { 2578 ssh_packet_send_debug(ssh, "No xauth program; cannot forward X11."); 2579 return 0; 2580 } 2581 if (s->display != NULL) { 2582 debug("X11 display already set."); 2583 return 0; 2584 } 2585 if (x11_create_display_inet(ssh, options.x11_display_offset, 2586 options.x11_use_localhost, s->single_connection, 2587 &s->display_number, &s->x11_chanids) == -1) { 2588 debug("x11_create_display_inet failed."); 2589 return 0; 2590 } 2591 for (i = 0; s->x11_chanids[i] != -1; i++) { 2592 channel_register_cleanup(ssh, s->x11_chanids[i], 2593 session_close_single_x11, 0); 2594 } 2595 2596 /* Set up a suitable value for the DISPLAY variable. */ 2597 if (gethostname(hostname, sizeof(hostname)) == -1) 2598 fatal("gethostname: %.100s", strerror(errno)); 2599 /* 2600 * auth_display must be used as the displayname when the 2601 * authorization entry is added with xauth(1). This will be 2602 * different than the DISPLAY string for localhost displays. 2603 */ 2604 if (options.x11_use_localhost) { 2605 snprintf(display, sizeof display, "localhost:%u.%u", 2606 s->display_number, s->screen); 2607 snprintf(auth_display, sizeof auth_display, "unix:%u.%u", 2608 s->display_number, s->screen); 2609 s->display = xstrdup(display); 2610 s->auth_display = xstrdup(auth_display); 2611 } else { 2612 #ifdef IPADDR_IN_DISPLAY 2613 struct hostent *he; 2614 struct in_addr my_addr; 2615 2616 he = gethostbyname(hostname); 2617 if (he == NULL) { 2618 error("Can't get IP address for X11 DISPLAY."); 2619 ssh_packet_send_debug(ssh, "Can't get IP address for X11 DISPLAY."); 2620 return 0; 2621 } 2622 memcpy(&my_addr, he->h_addr_list[0], sizeof(struct in_addr)); 2623 snprintf(display, sizeof display, "%.50s:%u.%u", inet_ntoa(my_addr), 2624 s->display_number, s->screen); 2625 #else 2626 snprintf(display, sizeof display, "%.400s:%u.%u", hostname, 2627 s->display_number, s->screen); 2628 #endif 2629 s->display = xstrdup(display); 2630 s->auth_display = xstrdup(display); 2631 } 2632 2633 return 1; 2634 } 2635 2636 static void 2637 do_authenticated2(struct ssh *ssh, Authctxt *authctxt) 2638 { 2639 server_loop2(ssh, authctxt); 2640 } 2641 2642 void 2643 do_cleanup(struct ssh *ssh, Authctxt *authctxt) 2644 { 2645 static int called = 0; 2646 2647 debug("do_cleanup"); 2648 2649 /* no cleanup if we're in the child for login shell */ 2650 if (is_child) 2651 return; 2652 2653 /* avoid double cleanup */ 2654 if (called) 2655 return; 2656 called = 1; 2657 2658 if (authctxt == NULL) 2659 return; 2660 2661 #ifdef USE_PAM 2662 if (options.use_pam) { 2663 sshpam_cleanup(); 2664 sshpam_thread_cleanup(); 2665 } 2666 #endif 2667 2668 if (!authctxt->authenticated) 2669 return; 2670 2671 #ifdef KRB5 2672 if (options.kerberos_ticket_cleanup && 2673 authctxt->krb5_ctx) 2674 krb5_cleanup_proc(authctxt); 2675 #endif 2676 2677 #ifdef GSSAPI 2678 if (options.gss_cleanup_creds) 2679 ssh_gssapi_cleanup_creds(); 2680 #endif 2681 2682 /* remove agent socket */ 2683 auth_sock_cleanup_proc(authctxt->pw); 2684 2685 /* remove userauth info */ 2686 if (auth_info_file != NULL) { 2687 temporarily_use_uid(authctxt->pw); 2688 unlink(auth_info_file); 2689 restore_uid(); 2690 free(auth_info_file); 2691 auth_info_file = NULL; 2692 } 2693 2694 /* 2695 * Cleanup ptys/utmp only if privsep is disabled, 2696 * or if running in monitor. 2697 */ 2698 if (!use_privsep || mm_is_monitor()) 2699 session_destroy_all(ssh, session_pty_cleanup2); 2700 } 2701 2702 /* Return a name for the remote host that fits inside utmp_size */ 2703 2704 const char * 2705 session_get_remote_name_or_ip(struct ssh *ssh, u_int utmp_size, int use_dns) 2706 { 2707 const char *remote = ""; 2708 2709 if (utmp_size > 0) 2710 remote = auth_get_canonical_hostname(ssh, use_dns); 2711 if (utmp_size == 0 || strlen(remote) > utmp_size) 2712 remote = ssh_remote_ipaddr(ssh); 2713 return remote; 2714 } 2715 2716