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 __RCSID("$FreeBSD$"); 38 39 #include <sys/types.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 = hpdelim2(&cp, NULL)) == 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 #else 994 extern char **environ; 995 char **senv, **var, *val; 996 #endif 997 998 /* Initialize the environment. */ 999 envsize = 100; 1000 env = xcalloc(envsize, sizeof(char *)); 1001 env[0] = NULL; 1002 1003 #ifdef HAVE_CYGWIN 1004 /* 1005 * The Windows environment contains some setting which are 1006 * important for a running system. They must not be dropped. 1007 */ 1008 { 1009 char **p; 1010 1011 p = fetch_windows_environment(); 1012 copy_environment(p, &env, &envsize); 1013 free_windows_environment(p); 1014 } 1015 #endif 1016 1017 if (getenv("TZ")) 1018 child_set_env(&env, &envsize, "TZ", getenv("TZ")); 1019 1020 #ifdef GSSAPI 1021 /* Allow any GSSAPI methods that we've used to alter 1022 * the child's environment as they see fit 1023 */ 1024 ssh_gssapi_do_child(&env, &envsize); 1025 #endif 1026 1027 /* Set basic environment. */ 1028 for (i = 0; i < s->num_env; i++) 1029 child_set_env(&env, &envsize, s->env[i].name, s->env[i].val); 1030 1031 child_set_env(&env, &envsize, "USER", pw->pw_name); 1032 child_set_env(&env, &envsize, "LOGNAME", pw->pw_name); 1033 #ifdef _AIX 1034 child_set_env(&env, &envsize, "LOGIN", pw->pw_name); 1035 #endif 1036 child_set_env(&env, &envsize, "HOME", pw->pw_dir); 1037 snprintf(buf, sizeof buf, "%.200s/%.50s", _PATH_MAILDIR, pw->pw_name); 1038 child_set_env(&env, &envsize, "MAIL", buf); 1039 #ifdef HAVE_LOGIN_CAP 1040 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); 1041 child_set_env(&env, &envsize, "TERM", "su"); 1042 /* 1043 * Temporarily swap out our real environment with an empty one, 1044 * let setusercontext() apply any environment variables defined 1045 * for the user's login class, copy those variables to the child, 1046 * free the temporary environment, and restore the original. 1047 */ 1048 senv = environ; 1049 environ = xmalloc(sizeof(*environ)); 1050 *environ = NULL; 1051 (void)setusercontext(lc, pw, pw->pw_uid, LOGIN_SETENV|LOGIN_SETPATH); 1052 for (var = environ; *var != NULL; ++var) { 1053 if ((val = strchr(*var, '=')) != NULL) { 1054 *val++ = '\0'; 1055 child_set_env(&env, &envsize, *var, val); 1056 } 1057 free(*var); 1058 } 1059 free(environ); 1060 environ = senv; 1061 #else /* HAVE_LOGIN_CAP */ 1062 # ifndef HAVE_CYGWIN 1063 /* 1064 * There's no standard path on Windows. The path contains 1065 * important components pointing to the system directories, 1066 * needed for loading shared libraries. So the path better 1067 * remains intact here. 1068 */ 1069 # ifdef HAVE_ETC_DEFAULT_LOGIN 1070 read_etc_default_login(&env, &envsize, pw->pw_uid); 1071 path = child_get_env(env, "PATH"); 1072 # endif /* HAVE_ETC_DEFAULT_LOGIN */ 1073 if (path == NULL || *path == '\0') { 1074 child_set_env(&env, &envsize, "PATH", 1075 s->pw->pw_uid == 0 ? SUPERUSER_PATH : _PATH_STDPATH); 1076 } 1077 # endif /* HAVE_CYGWIN */ 1078 #endif /* HAVE_LOGIN_CAP */ 1079 1080 if (!options.use_pam) { 1081 snprintf(buf, sizeof buf, "%.200s/%.50s", 1082 _PATH_MAILDIR, pw->pw_name); 1083 child_set_env(&env, &envsize, "MAIL", buf); 1084 } 1085 1086 /* Normal systems set SHELL by default. */ 1087 child_set_env(&env, &envsize, "SHELL", shell); 1088 1089 if (s->term) 1090 child_set_env(&env, &envsize, "TERM", s->term); 1091 if (s->display) 1092 child_set_env(&env, &envsize, "DISPLAY", s->display); 1093 1094 /* 1095 * Since we clear KRB5CCNAME at startup, if it's set now then it 1096 * must have been set by a native authentication method (eg AIX or 1097 * SIA), so copy it to the child. 1098 */ 1099 { 1100 char *cp; 1101 1102 if ((cp = getenv("KRB5CCNAME")) != NULL) 1103 child_set_env(&env, &envsize, "KRB5CCNAME", cp); 1104 } 1105 1106 #ifdef _AIX 1107 { 1108 char *cp; 1109 1110 if ((cp = getenv("AUTHSTATE")) != NULL) 1111 child_set_env(&env, &envsize, "AUTHSTATE", cp); 1112 read_environment_file(&env, &envsize, "/etc/environment", 1113 options.permit_user_env_allowlist); 1114 } 1115 #endif 1116 #ifdef KRB5 1117 if (s->authctxt->krb5_ccname) 1118 child_set_env(&env, &envsize, "KRB5CCNAME", 1119 s->authctxt->krb5_ccname); 1120 #endif 1121 if (auth_sock_name != NULL) 1122 child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME, 1123 auth_sock_name); 1124 1125 1126 /* Set custom environment options from pubkey authentication. */ 1127 if (options.permit_user_env) { 1128 for (n = 0 ; n < auth_opts->nenv; n++) { 1129 ocp = xstrdup(auth_opts->env[n]); 1130 cp = strchr(ocp, '='); 1131 if (cp != NULL) { 1132 *cp = '\0'; 1133 /* Apply PermitUserEnvironment allowlist */ 1134 if (options.permit_user_env_allowlist == NULL || 1135 match_pattern_list(ocp, 1136 options.permit_user_env_allowlist, 0) == 1) 1137 child_set_env(&env, &envsize, 1138 ocp, cp + 1); 1139 } 1140 free(ocp); 1141 } 1142 } 1143 1144 /* read $HOME/.ssh/environment. */ 1145 if (options.permit_user_env) { 1146 snprintf(buf, sizeof buf, "%.200s/%s/environment", 1147 pw->pw_dir, _PATH_SSH_USER_DIR); 1148 read_environment_file(&env, &envsize, buf, 1149 options.permit_user_env_allowlist); 1150 } 1151 1152 #ifdef USE_PAM 1153 /* 1154 * Pull in any environment variables that may have 1155 * been set by PAM. 1156 */ 1157 if (options.use_pam) { 1158 char **p; 1159 1160 /* 1161 * Don't allow PAM-internal env vars to leak 1162 * back into the session environment. 1163 */ 1164 #define PAM_ENV_DENYLIST "SSH_AUTH_INFO*,SSH_CONNECTION*" 1165 p = fetch_pam_child_environment(); 1166 copy_environment_denylist(p, &env, &envsize, 1167 PAM_ENV_DENYLIST); 1168 free_pam_environment(p); 1169 1170 p = fetch_pam_environment(); 1171 copy_environment_denylist(p, &env, &envsize, 1172 PAM_ENV_DENYLIST); 1173 free_pam_environment(p); 1174 } 1175 #endif /* USE_PAM */ 1176 1177 /* Environment specified by admin */ 1178 for (i = 0; i < options.num_setenv; i++) { 1179 cp = xstrdup(options.setenv[i]); 1180 if ((value = strchr(cp, '=')) == NULL) { 1181 /* shouldn't happen; vars are checked in servconf.c */ 1182 fatal("Invalid config SetEnv: %s", options.setenv[i]); 1183 } 1184 *value++ = '\0'; 1185 child_set_env(&env, &envsize, cp, value); 1186 } 1187 1188 /* SSH_CLIENT deprecated */ 1189 snprintf(buf, sizeof buf, "%.50s %d %d", 1190 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 1191 ssh_local_port(ssh)); 1192 child_set_env(&env, &envsize, "SSH_CLIENT", buf); 1193 1194 laddr = get_local_ipaddr(ssh_packet_get_connection_in(ssh)); 1195 snprintf(buf, sizeof buf, "%.50s %d %.50s %d", 1196 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 1197 laddr, ssh_local_port(ssh)); 1198 free(laddr); 1199 child_set_env(&env, &envsize, "SSH_CONNECTION", buf); 1200 1201 if (tun_fwd_ifnames != NULL) 1202 child_set_env(&env, &envsize, "SSH_TUNNEL", tun_fwd_ifnames); 1203 if (auth_info_file != NULL) 1204 child_set_env(&env, &envsize, "SSH_USER_AUTH", auth_info_file); 1205 if (s->ttyfd != -1) 1206 child_set_env(&env, &envsize, "SSH_TTY", s->tty); 1207 if (original_command) 1208 child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND", 1209 original_command); 1210 1211 if (debug_flag) { 1212 /* dump the environment */ 1213 fprintf(stderr, "Environment:\n"); 1214 for (i = 0; env[i]; i++) 1215 fprintf(stderr, " %.200s\n", env[i]); 1216 } 1217 return env; 1218 } 1219 1220 /* 1221 * Run $HOME/.ssh/rc, /etc/ssh/sshrc, or xauth (whichever is found 1222 * first in this order). 1223 */ 1224 static void 1225 do_rc_files(struct ssh *ssh, Session *s, const char *shell) 1226 { 1227 FILE *f = NULL; 1228 char *cmd = NULL, *user_rc = NULL; 1229 int do_xauth; 1230 struct stat st; 1231 1232 do_xauth = 1233 s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL; 1234 xasprintf(&user_rc, "%s/%s", s->pw->pw_dir, _PATH_SSH_USER_RC); 1235 1236 /* ignore _PATH_SSH_USER_RC for subsystems and admin forced commands */ 1237 if (!s->is_subsystem && options.adm_forced_command == NULL && 1238 auth_opts->permit_user_rc && options.permit_user_rc && 1239 stat(user_rc, &st) >= 0) { 1240 if (xasprintf(&cmd, "%s -c '%s %s'", shell, _PATH_BSHELL, 1241 user_rc) == -1) 1242 fatal_f("xasprintf: %s", strerror(errno)); 1243 if (debug_flag) 1244 fprintf(stderr, "Running %s\n", cmd); 1245 f = popen(cmd, "w"); 1246 if (f) { 1247 if (do_xauth) 1248 fprintf(f, "%s %s\n", s->auth_proto, 1249 s->auth_data); 1250 pclose(f); 1251 } else 1252 fprintf(stderr, "Could not run %s\n", 1253 user_rc); 1254 } else if (stat(_PATH_SSH_SYSTEM_RC, &st) >= 0) { 1255 if (debug_flag) 1256 fprintf(stderr, "Running %s %s\n", _PATH_BSHELL, 1257 _PATH_SSH_SYSTEM_RC); 1258 f = popen(_PATH_BSHELL " " _PATH_SSH_SYSTEM_RC, "w"); 1259 if (f) { 1260 if (do_xauth) 1261 fprintf(f, "%s %s\n", s->auth_proto, 1262 s->auth_data); 1263 pclose(f); 1264 } else 1265 fprintf(stderr, "Could not run %s\n", 1266 _PATH_SSH_SYSTEM_RC); 1267 } else if (do_xauth && options.xauth_location != NULL) { 1268 /* Add authority data to .Xauthority if appropriate. */ 1269 if (debug_flag) { 1270 fprintf(stderr, 1271 "Running %.500s remove %.100s\n", 1272 options.xauth_location, s->auth_display); 1273 fprintf(stderr, 1274 "%.500s add %.100s %.100s %.100s\n", 1275 options.xauth_location, s->auth_display, 1276 s->auth_proto, s->auth_data); 1277 } 1278 if (xasprintf(&cmd, "%s -q -", options.xauth_location) == -1) 1279 fatal_f("xasprintf: %s", strerror(errno)); 1280 f = popen(cmd, "w"); 1281 if (f) { 1282 fprintf(f, "remove %s\n", 1283 s->auth_display); 1284 fprintf(f, "add %s %s %s\n", 1285 s->auth_display, s->auth_proto, 1286 s->auth_data); 1287 pclose(f); 1288 } else { 1289 fprintf(stderr, "Could not run %s\n", 1290 cmd); 1291 } 1292 } 1293 free(cmd); 1294 free(user_rc); 1295 } 1296 1297 static void 1298 do_nologin(struct passwd *pw) 1299 { 1300 FILE *f = NULL; 1301 const char *nl; 1302 char buf[1024], *def_nl = _PATH_NOLOGIN; 1303 struct stat sb; 1304 1305 #ifdef HAVE_LOGIN_CAP 1306 if (login_getcapbool(lc, "ignorenologin", 0) || pw->pw_uid == 0) 1307 return; 1308 nl = login_getcapstr(lc, "nologin", def_nl, def_nl); 1309 #else 1310 if (pw->pw_uid == 0) 1311 return; 1312 nl = def_nl; 1313 #endif 1314 if (stat(nl, &sb) == -1) 1315 return; 1316 1317 /* /etc/nologin exists. Print its contents if we can and exit. */ 1318 logit("User %.100s not allowed because %s exists", pw->pw_name, nl); 1319 if ((f = fopen(nl, "r")) != NULL) { 1320 while (fgets(buf, sizeof(buf), f)) 1321 fputs(buf, stderr); 1322 fclose(f); 1323 } 1324 exit(254); 1325 } 1326 1327 /* 1328 * Chroot into a directory after checking it for safety: all path components 1329 * must be root-owned directories with strict permissions. 1330 */ 1331 static void 1332 safely_chroot(const char *path, uid_t uid) 1333 { 1334 const char *cp; 1335 char component[PATH_MAX]; 1336 struct stat st; 1337 1338 if (!path_absolute(path)) 1339 fatal("chroot path does not begin at root"); 1340 if (strlen(path) >= sizeof(component)) 1341 fatal("chroot path too long"); 1342 1343 /* 1344 * Descend the path, checking that each component is a 1345 * root-owned directory with strict permissions. 1346 */ 1347 for (cp = path; cp != NULL;) { 1348 if ((cp = strchr(cp, '/')) == NULL) 1349 strlcpy(component, path, sizeof(component)); 1350 else { 1351 cp++; 1352 memcpy(component, path, cp - path); 1353 component[cp - path] = '\0'; 1354 } 1355 1356 debug3_f("checking '%s'", component); 1357 1358 if (stat(component, &st) != 0) 1359 fatal_f("stat(\"%s\"): %s", 1360 component, strerror(errno)); 1361 if (st.st_uid != 0 || (st.st_mode & 022) != 0) 1362 fatal("bad ownership or modes for chroot " 1363 "directory %s\"%s\"", 1364 cp == NULL ? "" : "component ", component); 1365 if (!S_ISDIR(st.st_mode)) 1366 fatal("chroot path %s\"%s\" is not a directory", 1367 cp == NULL ? "" : "component ", component); 1368 1369 } 1370 1371 if (chdir(path) == -1) 1372 fatal("Unable to chdir to chroot path \"%s\": " 1373 "%s", path, strerror(errno)); 1374 if (chroot(path) == -1) 1375 fatal("chroot(\"%s\"): %s", path, strerror(errno)); 1376 if (chdir("/") == -1) 1377 fatal_f("chdir(/) after chroot: %s", strerror(errno)); 1378 verbose("Changed root directory to \"%s\"", path); 1379 } 1380 1381 /* Set login name, uid, gid, and groups. */ 1382 void 1383 do_setusercontext(struct passwd *pw) 1384 { 1385 char uidstr[32], *chroot_path, *tmp; 1386 1387 platform_setusercontext(pw); 1388 1389 if (platform_privileged_uidswap()) { 1390 #ifdef HAVE_LOGIN_CAP 1391 if (setusercontext(lc, pw, pw->pw_uid, 1392 (LOGIN_SETALL & ~(LOGIN_SETENV|LOGIN_SETPATH|LOGIN_SETUSER))) < 0) { 1393 perror("unable to set user context"); 1394 exit(1); 1395 } 1396 #else 1397 if (setlogin(pw->pw_name) < 0) 1398 error("setlogin failed: %s", strerror(errno)); 1399 if (setgid(pw->pw_gid) < 0) { 1400 perror("setgid"); 1401 exit(1); 1402 } 1403 /* Initialize the group list. */ 1404 if (initgroups(pw->pw_name, pw->pw_gid) < 0) { 1405 perror("initgroups"); 1406 exit(1); 1407 } 1408 endgrent(); 1409 #endif 1410 1411 platform_setusercontext_post_groups(pw); 1412 1413 if (!in_chroot && options.chroot_directory != NULL && 1414 strcasecmp(options.chroot_directory, "none") != 0) { 1415 tmp = tilde_expand_filename(options.chroot_directory, 1416 pw->pw_uid); 1417 snprintf(uidstr, sizeof(uidstr), "%llu", 1418 (unsigned long long)pw->pw_uid); 1419 chroot_path = percent_expand(tmp, "h", pw->pw_dir, 1420 "u", pw->pw_name, "U", uidstr, (char *)NULL); 1421 safely_chroot(chroot_path, pw->pw_uid); 1422 free(tmp); 1423 free(chroot_path); 1424 /* Make sure we don't attempt to chroot again */ 1425 free(options.chroot_directory); 1426 options.chroot_directory = NULL; 1427 in_chroot = 1; 1428 } 1429 1430 #ifdef HAVE_LOGIN_CAP 1431 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUSER) < 0) { 1432 perror("unable to set user context (setuser)"); 1433 exit(1); 1434 } 1435 /* 1436 * FreeBSD's setusercontext() will not apply the user's 1437 * own umask setting unless running with the user's UID. 1438 */ 1439 (void) setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUMASK); 1440 #else 1441 # ifdef USE_LIBIAF 1442 /* 1443 * In a chroot environment, the set_id() will always fail; 1444 * typically because of the lack of necessary authentication 1445 * services and runtime such as ./usr/lib/libiaf.so, 1446 * ./usr/lib/libpam.so.1, and ./etc/passwd We skip it in the 1447 * internal sftp chroot case. We'll lose auditing and ACLs but 1448 * permanently_set_uid will take care of the rest. 1449 */ 1450 if (!in_chroot && set_id(pw->pw_name) != 0) 1451 fatal("set_id(%s) Failed", pw->pw_name); 1452 # endif /* USE_LIBIAF */ 1453 /* Permanently switch to the desired uid. */ 1454 permanently_set_uid(pw); 1455 #endif 1456 } else if (options.chroot_directory != NULL && 1457 strcasecmp(options.chroot_directory, "none") != 0) { 1458 fatal("server lacks privileges to chroot to ChrootDirectory"); 1459 } 1460 1461 if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) 1462 fatal("Failed to set uids to %u.", (u_int) pw->pw_uid); 1463 } 1464 1465 static void 1466 do_pwchange(Session *s) 1467 { 1468 fflush(NULL); 1469 fprintf(stderr, "WARNING: Your password has expired.\n"); 1470 if (s->ttyfd != -1) { 1471 fprintf(stderr, 1472 "You must change your password now and login again!\n"); 1473 #ifdef WITH_SELINUX 1474 setexeccon(NULL); 1475 #endif 1476 #ifdef PASSWD_NEEDS_USERNAME 1477 execl(_PATH_PASSWD_PROG, "passwd", s->pw->pw_name, 1478 (char *)NULL); 1479 #else 1480 execl(_PATH_PASSWD_PROG, "passwd", (char *)NULL); 1481 #endif 1482 perror("passwd"); 1483 } else { 1484 fprintf(stderr, 1485 "Password change required but no TTY available.\n"); 1486 } 1487 exit(1); 1488 } 1489 1490 static void 1491 child_close_fds(struct ssh *ssh) 1492 { 1493 extern int auth_sock; 1494 1495 if (auth_sock != -1) { 1496 close(auth_sock); 1497 auth_sock = -1; 1498 } 1499 1500 if (ssh_packet_get_connection_in(ssh) == 1501 ssh_packet_get_connection_out(ssh)) 1502 close(ssh_packet_get_connection_in(ssh)); 1503 else { 1504 close(ssh_packet_get_connection_in(ssh)); 1505 close(ssh_packet_get_connection_out(ssh)); 1506 } 1507 /* 1508 * Close all descriptors related to channels. They will still remain 1509 * open in the parent. 1510 */ 1511 /* XXX better use close-on-exec? -markus */ 1512 channel_close_all(ssh); 1513 1514 /* 1515 * Close any extra file descriptors. Note that there may still be 1516 * descriptors left by system functions. They will be closed later. 1517 */ 1518 endpwent(); 1519 1520 /* Stop directing logs to a high-numbered fd before we close it */ 1521 log_redirect_stderr_to(NULL); 1522 1523 /* 1524 * Close any extra open file descriptors so that we don't have them 1525 * hanging around in clients. Note that we want to do this after 1526 * initgroups, because at least on Solaris 2.3 it leaves file 1527 * descriptors open. 1528 */ 1529 closefrom(STDERR_FILENO + 1); 1530 } 1531 1532 /* 1533 * Performs common processing for the child, such as setting up the 1534 * environment, closing extra file descriptors, setting the user and group 1535 * ids, and executing the command or shell. 1536 */ 1537 #define ARGV_MAX 10 1538 void 1539 do_child(struct ssh *ssh, Session *s, const char *command) 1540 { 1541 extern char **environ; 1542 char **env, *argv[ARGV_MAX], remote_id[512]; 1543 const char *shell, *shell0; 1544 struct passwd *pw = s->pw; 1545 int r = 0; 1546 1547 sshpkt_fmt_connection_id(ssh, remote_id, sizeof(remote_id)); 1548 1549 /* remove hostkey from the child's memory */ 1550 destroy_sensitive_data(); 1551 ssh_packet_clear_keys(ssh); 1552 1553 /* Force a password change */ 1554 if (s->authctxt->force_pwchange) { 1555 do_setusercontext(pw); 1556 child_close_fds(ssh); 1557 do_pwchange(s); 1558 exit(1); 1559 } 1560 1561 /* 1562 * Login(1) does this as well, and it needs uid 0 for the "-h" 1563 * switch, so we let login(1) to this for us. 1564 */ 1565 #ifdef HAVE_OSF_SIA 1566 session_setup_sia(pw, s->ttyfd == -1 ? NULL : s->tty); 1567 if (!check_quietlogin(s, command)) 1568 do_motd(); 1569 #else /* HAVE_OSF_SIA */ 1570 /* When PAM is enabled we rely on it to do the nologin check */ 1571 if (!options.use_pam) 1572 do_nologin(pw); 1573 do_setusercontext(pw); 1574 /* 1575 * PAM session modules in do_setusercontext may have 1576 * generated messages, so if this in an interactive 1577 * login then display them too. 1578 */ 1579 if (!check_quietlogin(s, command)) 1580 display_loginmsg(); 1581 #endif /* HAVE_OSF_SIA */ 1582 1583 #ifdef USE_PAM 1584 if (options.use_pam && !is_pam_session_open()) { 1585 debug3("PAM session not opened, exiting"); 1586 display_loginmsg(); 1587 exit(254); 1588 } 1589 #endif 1590 1591 /* 1592 * Get the shell from the password data. An empty shell field is 1593 * legal, and means /bin/sh. 1594 */ 1595 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; 1596 1597 /* 1598 * Make sure $SHELL points to the shell from the password file, 1599 * even if shell is overridden from login.conf 1600 */ 1601 env = do_setup_env(ssh, s, shell); 1602 1603 #ifdef HAVE_LOGIN_CAP 1604 shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell); 1605 #endif 1606 1607 /* 1608 * Close the connection descriptors; note that this is the child, and 1609 * the server will still have the socket open, and it is important 1610 * that we do not shutdown it. Note that the descriptors cannot be 1611 * closed before building the environment, as we call 1612 * ssh_remote_ipaddr there. 1613 */ 1614 child_close_fds(ssh); 1615 1616 /* 1617 * Must take new environment into use so that .ssh/rc, 1618 * /etc/ssh/sshrc and xauth are run in the proper environment. 1619 */ 1620 environ = env; 1621 1622 #if defined(KRB5) && defined(USE_AFS) 1623 /* 1624 * At this point, we check to see if AFS is active and if we have 1625 * a valid Kerberos 5 TGT. If so, it seems like a good idea to see 1626 * if we can (and need to) extend the ticket into an AFS token. If 1627 * we don't do this, we run into potential problems if the user's 1628 * home directory is in AFS and it's not world-readable. 1629 */ 1630 1631 if (options.kerberos_get_afs_token && k_hasafs() && 1632 (s->authctxt->krb5_ctx != NULL)) { 1633 char cell[64]; 1634 1635 debug("Getting AFS token"); 1636 1637 k_setpag(); 1638 1639 if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0) 1640 krb5_afslog(s->authctxt->krb5_ctx, 1641 s->authctxt->krb5_fwd_ccache, cell, NULL); 1642 1643 krb5_afslog_home(s->authctxt->krb5_ctx, 1644 s->authctxt->krb5_fwd_ccache, NULL, NULL, pw->pw_dir); 1645 } 1646 #endif 1647 1648 /* Change current directory to the user's home directory. */ 1649 if (chdir(pw->pw_dir) == -1) { 1650 /* Suppress missing homedir warning for chroot case */ 1651 #ifdef HAVE_LOGIN_CAP 1652 r = login_getcapbool(lc, "requirehome", 0); 1653 #endif 1654 if (r || !in_chroot) { 1655 fprintf(stderr, "Could not chdir to home " 1656 "directory %s: %s\n", pw->pw_dir, 1657 strerror(errno)); 1658 } 1659 if (r) 1660 exit(1); 1661 } 1662 1663 closefrom(STDERR_FILENO + 1); 1664 1665 do_rc_files(ssh, s, shell); 1666 1667 /* restore SIGPIPE for child */ 1668 ssh_signal(SIGPIPE, SIG_DFL); 1669 1670 if (s->is_subsystem == SUBSYSTEM_INT_SFTP_ERROR) { 1671 error("Connection from %s: refusing non-sftp session", 1672 remote_id); 1673 printf("This service allows sftp connections only.\n"); 1674 fflush(NULL); 1675 exit(1); 1676 } else if (s->is_subsystem == SUBSYSTEM_INT_SFTP) { 1677 extern int optind, optreset; 1678 int i; 1679 char *p, *args; 1680 1681 setproctitle("%s@%s", s->pw->pw_name, INTERNAL_SFTP_NAME); 1682 args = xstrdup(command ? command : "sftp-server"); 1683 for (i = 0, (p = strtok(args, " ")); p; (p = strtok(NULL, " "))) 1684 if (i < ARGV_MAX - 1) 1685 argv[i++] = p; 1686 argv[i] = NULL; 1687 optind = optreset = 1; 1688 __progname = argv[0]; 1689 #ifdef WITH_SELINUX 1690 ssh_selinux_change_context("sftpd_t"); 1691 #endif 1692 exit(sftp_server_main(i, argv, s->pw)); 1693 } 1694 1695 fflush(NULL); 1696 1697 /* Get the last component of the shell name. */ 1698 if ((shell0 = strrchr(shell, '/')) != NULL) 1699 shell0++; 1700 else 1701 shell0 = shell; 1702 1703 /* 1704 * If we have no command, execute the shell. In this case, the shell 1705 * name to be passed in argv[0] is preceded by '-' to indicate that 1706 * this is a login shell. 1707 */ 1708 if (!command) { 1709 char argv0[256]; 1710 1711 /* Start the shell. Set initial character to '-'. */ 1712 argv0[0] = '-'; 1713 1714 if (strlcpy(argv0 + 1, shell0, sizeof(argv0) - 1) 1715 >= sizeof(argv0) - 1) { 1716 errno = EINVAL; 1717 perror(shell); 1718 exit(1); 1719 } 1720 1721 /* Execute the shell. */ 1722 argv[0] = argv0; 1723 argv[1] = NULL; 1724 execve(shell, argv, env); 1725 1726 /* Executing the shell failed. */ 1727 perror(shell); 1728 exit(1); 1729 } 1730 /* 1731 * Execute the command using the user's shell. This uses the -c 1732 * option to execute the command. 1733 */ 1734 argv[0] = (char *) shell0; 1735 argv[1] = "-c"; 1736 argv[2] = (char *) command; 1737 argv[3] = NULL; 1738 execve(shell, argv, env); 1739 perror(shell); 1740 exit(1); 1741 } 1742 1743 void 1744 session_unused(int id) 1745 { 1746 debug3_f("session id %d unused", id); 1747 if (id >= options.max_sessions || 1748 id >= sessions_nalloc) { 1749 fatal_f("insane session id %d (max %d nalloc %d)", 1750 id, options.max_sessions, sessions_nalloc); 1751 } 1752 memset(&sessions[id], 0, sizeof(*sessions)); 1753 sessions[id].self = id; 1754 sessions[id].used = 0; 1755 sessions[id].chanid = -1; 1756 sessions[id].ptyfd = -1; 1757 sessions[id].ttyfd = -1; 1758 sessions[id].ptymaster = -1; 1759 sessions[id].x11_chanids = NULL; 1760 sessions[id].next_unused = sessions_first_unused; 1761 sessions_first_unused = id; 1762 } 1763 1764 Session * 1765 session_new(void) 1766 { 1767 Session *s, *tmp; 1768 1769 if (sessions_first_unused == -1) { 1770 if (sessions_nalloc >= options.max_sessions) 1771 return NULL; 1772 debug2_f("allocate (allocated %d max %d)", 1773 sessions_nalloc, options.max_sessions); 1774 tmp = xrecallocarray(sessions, sessions_nalloc, 1775 sessions_nalloc + 1, sizeof(*sessions)); 1776 if (tmp == NULL) { 1777 error_f("cannot allocate %d sessions", 1778 sessions_nalloc + 1); 1779 return NULL; 1780 } 1781 sessions = tmp; 1782 session_unused(sessions_nalloc++); 1783 } 1784 1785 if (sessions_first_unused >= sessions_nalloc || 1786 sessions_first_unused < 0) { 1787 fatal_f("insane first_unused %d max %d nalloc %d", 1788 sessions_first_unused, options.max_sessions, 1789 sessions_nalloc); 1790 } 1791 1792 s = &sessions[sessions_first_unused]; 1793 if (s->used) 1794 fatal_f("session %d already used", sessions_first_unused); 1795 sessions_first_unused = s->next_unused; 1796 s->used = 1; 1797 s->next_unused = -1; 1798 debug("session_new: session %d", s->self); 1799 1800 return s; 1801 } 1802 1803 static void 1804 session_dump(void) 1805 { 1806 int i; 1807 for (i = 0; i < sessions_nalloc; i++) { 1808 Session *s = &sessions[i]; 1809 1810 debug("dump: used %d next_unused %d session %d " 1811 "channel %d pid %ld", 1812 s->used, 1813 s->next_unused, 1814 s->self, 1815 s->chanid, 1816 (long)s->pid); 1817 } 1818 } 1819 1820 int 1821 session_open(Authctxt *authctxt, int chanid) 1822 { 1823 Session *s = session_new(); 1824 debug("session_open: channel %d", chanid); 1825 if (s == NULL) { 1826 error("no more sessions"); 1827 return 0; 1828 } 1829 s->authctxt = authctxt; 1830 s->pw = authctxt->pw; 1831 if (s->pw == NULL || !authctxt->valid) 1832 fatal("no user for session %d", s->self); 1833 debug("session_open: session %d: link with channel %d", s->self, chanid); 1834 s->chanid = chanid; 1835 return 1; 1836 } 1837 1838 Session * 1839 session_by_tty(char *tty) 1840 { 1841 int i; 1842 for (i = 0; i < sessions_nalloc; i++) { 1843 Session *s = &sessions[i]; 1844 if (s->used && s->ttyfd != -1 && strcmp(s->tty, tty) == 0) { 1845 debug("session_by_tty: session %d tty %s", i, tty); 1846 return s; 1847 } 1848 } 1849 debug("session_by_tty: unknown tty %.100s", tty); 1850 session_dump(); 1851 return NULL; 1852 } 1853 1854 static Session * 1855 session_by_channel(int id) 1856 { 1857 int i; 1858 for (i = 0; i < sessions_nalloc; i++) { 1859 Session *s = &sessions[i]; 1860 if (s->used && s->chanid == id) { 1861 debug("session_by_channel: session %d channel %d", 1862 i, id); 1863 return s; 1864 } 1865 } 1866 debug("session_by_channel: unknown channel %d", id); 1867 session_dump(); 1868 return NULL; 1869 } 1870 1871 static Session * 1872 session_by_x11_channel(int id) 1873 { 1874 int i, j; 1875 1876 for (i = 0; i < sessions_nalloc; i++) { 1877 Session *s = &sessions[i]; 1878 1879 if (s->x11_chanids == NULL || !s->used) 1880 continue; 1881 for (j = 0; s->x11_chanids[j] != -1; j++) { 1882 if (s->x11_chanids[j] == id) { 1883 debug("session_by_x11_channel: session %d " 1884 "channel %d", s->self, id); 1885 return s; 1886 } 1887 } 1888 } 1889 debug("session_by_x11_channel: unknown channel %d", id); 1890 session_dump(); 1891 return NULL; 1892 } 1893 1894 static Session * 1895 session_by_pid(pid_t pid) 1896 { 1897 int i; 1898 debug("session_by_pid: pid %ld", (long)pid); 1899 for (i = 0; i < sessions_nalloc; i++) { 1900 Session *s = &sessions[i]; 1901 if (s->used && s->pid == pid) 1902 return s; 1903 } 1904 error("session_by_pid: unknown pid %ld", (long)pid); 1905 session_dump(); 1906 return NULL; 1907 } 1908 1909 static int 1910 session_window_change_req(struct ssh *ssh, Session *s) 1911 { 1912 int r; 1913 1914 if ((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 (r = sshpkt_get_end(ssh)) != 0) 1919 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 1920 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 1921 return 1; 1922 } 1923 1924 static int 1925 session_pty_req(struct ssh *ssh, Session *s) 1926 { 1927 int r; 1928 1929 if (!auth_opts->permit_pty_flag || !options.permit_tty) { 1930 debug("Allocating a pty not permitted for this connection."); 1931 return 0; 1932 } 1933 if (s->ttyfd != -1) { 1934 ssh_packet_disconnect(ssh, "Protocol error: you already have a pty."); 1935 return 0; 1936 } 1937 1938 if ((r = sshpkt_get_cstring(ssh, &s->term, NULL)) != 0 || 1939 (r = sshpkt_get_u32(ssh, &s->col)) != 0 || 1940 (r = sshpkt_get_u32(ssh, &s->row)) != 0 || 1941 (r = sshpkt_get_u32(ssh, &s->xpixel)) != 0 || 1942 (r = sshpkt_get_u32(ssh, &s->ypixel)) != 0) 1943 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 1944 1945 if (strcmp(s->term, "") == 0) { 1946 free(s->term); 1947 s->term = NULL; 1948 } 1949 1950 /* Allocate a pty and open it. */ 1951 debug("Allocating pty."); 1952 if (!PRIVSEP(pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, 1953 sizeof(s->tty)))) { 1954 free(s->term); 1955 s->term = NULL; 1956 s->ptyfd = -1; 1957 s->ttyfd = -1; 1958 error("session_pty_req: session %d alloc failed", s->self); 1959 return 0; 1960 } 1961 debug("session_pty_req: session %d alloc %s", s->self, s->tty); 1962 1963 ssh_tty_parse_modes(ssh, s->ttyfd); 1964 1965 if ((r = sshpkt_get_end(ssh)) != 0) 1966 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 1967 1968 if (!use_privsep) 1969 pty_setowner(s->pw, s->tty); 1970 1971 /* Set window size from the packet. */ 1972 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 1973 1974 session_proctitle(s); 1975 return 1; 1976 } 1977 1978 static int 1979 session_subsystem_req(struct ssh *ssh, Session *s) 1980 { 1981 struct stat st; 1982 int r, success = 0; 1983 char *prog, *cmd; 1984 u_int i; 1985 1986 if ((r = sshpkt_get_cstring(ssh, &s->subsys, NULL)) != 0 || 1987 (r = sshpkt_get_end(ssh)) != 0) 1988 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 1989 debug2("subsystem request for %.100s by user %s", s->subsys, 1990 s->pw->pw_name); 1991 1992 for (i = 0; i < options.num_subsystems; i++) { 1993 if (strcmp(s->subsys, options.subsystem_name[i]) == 0) { 1994 prog = options.subsystem_command[i]; 1995 cmd = options.subsystem_args[i]; 1996 if (strcmp(INTERNAL_SFTP_NAME, prog) == 0) { 1997 s->is_subsystem = SUBSYSTEM_INT_SFTP; 1998 debug("subsystem: %s", prog); 1999 } else { 2000 if (stat(prog, &st) == -1) 2001 debug("subsystem: cannot stat %s: %s", 2002 prog, strerror(errno)); 2003 s->is_subsystem = SUBSYSTEM_EXT; 2004 debug("subsystem: exec() %s", cmd); 2005 } 2006 success = do_exec(ssh, s, cmd) == 0; 2007 break; 2008 } 2009 } 2010 2011 if (!success) 2012 logit("subsystem request for %.100s by user %s failed, " 2013 "subsystem not found", s->subsys, s->pw->pw_name); 2014 2015 return success; 2016 } 2017 2018 static int 2019 session_x11_req(struct ssh *ssh, Session *s) 2020 { 2021 int r, success; 2022 u_char single_connection = 0; 2023 2024 if (s->auth_proto != NULL || s->auth_data != NULL) { 2025 error("session_x11_req: session %d: " 2026 "x11 forwarding already active", s->self); 2027 return 0; 2028 } 2029 if ((r = sshpkt_get_u8(ssh, &single_connection)) != 0 || 2030 (r = sshpkt_get_cstring(ssh, &s->auth_proto, NULL)) != 0 || 2031 (r = sshpkt_get_cstring(ssh, &s->auth_data, NULL)) != 0 || 2032 (r = sshpkt_get_u32(ssh, &s->screen)) != 0 || 2033 (r = sshpkt_get_end(ssh)) != 0) 2034 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 2035 2036 s->single_connection = single_connection; 2037 2038 if (xauth_valid_string(s->auth_proto) && 2039 xauth_valid_string(s->auth_data)) 2040 success = session_setup_x11fwd(ssh, s); 2041 else { 2042 success = 0; 2043 error("Invalid X11 forwarding data"); 2044 } 2045 if (!success) { 2046 free(s->auth_proto); 2047 free(s->auth_data); 2048 s->auth_proto = NULL; 2049 s->auth_data = NULL; 2050 } 2051 return success; 2052 } 2053 2054 static int 2055 session_shell_req(struct ssh *ssh, Session *s) 2056 { 2057 int r; 2058 2059 if ((r = sshpkt_get_end(ssh)) != 0) 2060 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 2061 return do_exec(ssh, s, NULL) == 0; 2062 } 2063 2064 static int 2065 session_exec_req(struct ssh *ssh, Session *s) 2066 { 2067 u_int success; 2068 int r; 2069 char *command = NULL; 2070 2071 if ((r = sshpkt_get_cstring(ssh, &command, NULL)) != 0 || 2072 (r = sshpkt_get_end(ssh)) != 0) 2073 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 2074 2075 success = do_exec(ssh, s, command) == 0; 2076 free(command); 2077 return success; 2078 } 2079 2080 static int 2081 session_break_req(struct ssh *ssh, Session *s) 2082 { 2083 int r; 2084 2085 if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* ignore */ 2086 (r = sshpkt_get_end(ssh)) != 0) 2087 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 2088 2089 if (s->ptymaster == -1 || tcsendbreak(s->ptymaster, 0) == -1) 2090 return 0; 2091 return 1; 2092 } 2093 2094 static int 2095 session_env_req(struct ssh *ssh, Session *s) 2096 { 2097 char *name, *val; 2098 u_int i; 2099 int r; 2100 2101 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 || 2102 (r = sshpkt_get_cstring(ssh, &val, NULL)) != 0 || 2103 (r = sshpkt_get_end(ssh)) != 0) 2104 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 2105 2106 /* Don't set too many environment variables */ 2107 if (s->num_env > 128) { 2108 debug2("Ignoring env request %s: too many env vars", name); 2109 goto fail; 2110 } 2111 2112 for (i = 0; i < options.num_accept_env; i++) { 2113 if (match_pattern(name, options.accept_env[i])) { 2114 debug2("Setting env %d: %s=%s", s->num_env, name, val); 2115 s->env = xrecallocarray(s->env, s->num_env, 2116 s->num_env + 1, sizeof(*s->env)); 2117 s->env[s->num_env].name = name; 2118 s->env[s->num_env].val = val; 2119 s->num_env++; 2120 return (1); 2121 } 2122 } 2123 debug2("Ignoring env request %s: disallowed name", name); 2124 2125 fail: 2126 free(name); 2127 free(val); 2128 return (0); 2129 } 2130 2131 /* 2132 * Conversion of signals from ssh channel request names. 2133 * Subset of signals from RFC 4254 section 6.10C, with SIGINFO as 2134 * local extension. 2135 */ 2136 static int 2137 name2sig(char *name) 2138 { 2139 #define SSH_SIG(x) if (strcmp(name, #x) == 0) return SIG ## x 2140 SSH_SIG(HUP); 2141 SSH_SIG(INT); 2142 SSH_SIG(KILL); 2143 SSH_SIG(QUIT); 2144 SSH_SIG(TERM); 2145 SSH_SIG(USR1); 2146 SSH_SIG(USR2); 2147 #undef SSH_SIG 2148 #ifdef SIGINFO 2149 if (strcmp(name, "INFO@openssh.com") == 0) 2150 return SIGINFO; 2151 #endif 2152 return -1; 2153 } 2154 2155 static int 2156 session_signal_req(struct ssh *ssh, Session *s) 2157 { 2158 char *signame = NULL; 2159 int r, sig, success = 0; 2160 2161 if ((r = sshpkt_get_cstring(ssh, &signame, NULL)) != 0 || 2162 (r = sshpkt_get_end(ssh)) != 0) { 2163 error_fr(r, "parse"); 2164 goto out; 2165 } 2166 if ((sig = name2sig(signame)) == -1) { 2167 error_f("unsupported signal \"%s\"", signame); 2168 goto out; 2169 } 2170 if (s->pid <= 0) { 2171 error_f("no pid for session %d", s->self); 2172 goto out; 2173 } 2174 if (s->forced || s->is_subsystem) { 2175 error_f("refusing to send signal %s to %s session", 2176 signame, s->forced ? "forced-command" : "subsystem"); 2177 goto out; 2178 } 2179 if (!use_privsep || mm_is_monitor()) { 2180 error_f("session signalling requires privilege separation"); 2181 goto out; 2182 } 2183 2184 debug_f("signal %s, killpg(%ld, %d)", signame, (long)s->pid, sig); 2185 temporarily_use_uid(s->pw); 2186 r = killpg(s->pid, sig); 2187 restore_uid(); 2188 if (r != 0) { 2189 error_f("killpg(%ld, %d): %s", (long)s->pid, 2190 sig, strerror(errno)); 2191 goto out; 2192 } 2193 2194 /* success */ 2195 success = 1; 2196 out: 2197 free(signame); 2198 return success; 2199 } 2200 2201 static int 2202 session_auth_agent_req(struct ssh *ssh, Session *s) 2203 { 2204 static int called = 0; 2205 int r; 2206 2207 if ((r = sshpkt_get_end(ssh)) != 0) 2208 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 2209 if (!auth_opts->permit_agent_forwarding_flag || 2210 !options.allow_agent_forwarding) { 2211 debug_f("agent forwarding disabled"); 2212 return 0; 2213 } 2214 if (called) { 2215 return 0; 2216 } else { 2217 called = 1; 2218 return auth_input_request_forwarding(ssh, s->pw); 2219 } 2220 } 2221 2222 int 2223 session_input_channel_req(struct ssh *ssh, Channel *c, const char *rtype) 2224 { 2225 int success = 0; 2226 Session *s; 2227 2228 if ((s = session_by_channel(c->self)) == NULL) { 2229 logit_f("no session %d req %.100s", c->self, rtype); 2230 return 0; 2231 } 2232 debug_f("session %d req %s", s->self, rtype); 2233 2234 /* 2235 * a session is in LARVAL state until a shell, a command 2236 * or a subsystem is executed 2237 */ 2238 if (c->type == SSH_CHANNEL_LARVAL) { 2239 if (strcmp(rtype, "shell") == 0) { 2240 success = session_shell_req(ssh, s); 2241 } else if (strcmp(rtype, "exec") == 0) { 2242 success = session_exec_req(ssh, s); 2243 } else if (strcmp(rtype, "pty-req") == 0) { 2244 success = session_pty_req(ssh, s); 2245 } else if (strcmp(rtype, "x11-req") == 0) { 2246 success = session_x11_req(ssh, s); 2247 } else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) { 2248 success = session_auth_agent_req(ssh, s); 2249 } else if (strcmp(rtype, "subsystem") == 0) { 2250 success = session_subsystem_req(ssh, s); 2251 } else if (strcmp(rtype, "env") == 0) { 2252 success = session_env_req(ssh, s); 2253 } 2254 } 2255 if (strcmp(rtype, "window-change") == 0) { 2256 success = session_window_change_req(ssh, s); 2257 } else if (strcmp(rtype, "break") == 0) { 2258 success = session_break_req(ssh, s); 2259 } else if (strcmp(rtype, "signal") == 0) { 2260 success = session_signal_req(ssh, s); 2261 } 2262 2263 return success; 2264 } 2265 2266 void 2267 session_set_fds(struct ssh *ssh, Session *s, 2268 int fdin, int fdout, int fderr, int ignore_fderr, int is_tty) 2269 { 2270 /* 2271 * now that have a child and a pipe to the child, 2272 * we can activate our channel and register the fd's 2273 */ 2274 if (s->chanid == -1) 2275 fatal("no channel for session %d", s->self); 2276 channel_set_fds(ssh, s->chanid, 2277 fdout, fdin, fderr, 2278 ignore_fderr ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ, 2279 1, is_tty, CHAN_SES_WINDOW_DEFAULT); 2280 } 2281 2282 /* 2283 * Function to perform pty cleanup. Also called if we get aborted abnormally 2284 * (e.g., due to a dropped connection). 2285 */ 2286 void 2287 session_pty_cleanup2(Session *s) 2288 { 2289 if (s == NULL) { 2290 error_f("no session"); 2291 return; 2292 } 2293 if (s->ttyfd == -1) 2294 return; 2295 2296 debug_f("session %d release %s", s->self, s->tty); 2297 2298 /* Record that the user has logged out. */ 2299 if (s->pid != 0) 2300 record_logout(s->pid, s->tty, s->pw->pw_name); 2301 2302 /* Release the pseudo-tty. */ 2303 if (getuid() == 0) 2304 pty_release(s->tty); 2305 2306 /* 2307 * Close the server side of the socket pairs. We must do this after 2308 * the pty cleanup, so that another process doesn't get this pty 2309 * while we're still cleaning up. 2310 */ 2311 if (s->ptymaster != -1 && close(s->ptymaster) == -1) 2312 error("close(s->ptymaster/%d): %s", 2313 s->ptymaster, strerror(errno)); 2314 2315 /* unlink pty from session */ 2316 s->ttyfd = -1; 2317 } 2318 2319 void 2320 session_pty_cleanup(Session *s) 2321 { 2322 PRIVSEP(session_pty_cleanup2(s)); 2323 } 2324 2325 static char * 2326 sig2name(int sig) 2327 { 2328 #define SSH_SIG(x) if (sig == SIG ## x) return #x 2329 SSH_SIG(ABRT); 2330 SSH_SIG(ALRM); 2331 SSH_SIG(FPE); 2332 SSH_SIG(HUP); 2333 SSH_SIG(ILL); 2334 SSH_SIG(INT); 2335 SSH_SIG(KILL); 2336 SSH_SIG(PIPE); 2337 SSH_SIG(QUIT); 2338 SSH_SIG(SEGV); 2339 SSH_SIG(TERM); 2340 SSH_SIG(USR1); 2341 SSH_SIG(USR2); 2342 #undef SSH_SIG 2343 return "SIG@openssh.com"; 2344 } 2345 2346 static void 2347 session_close_x11(struct ssh *ssh, int id) 2348 { 2349 Channel *c; 2350 2351 if ((c = channel_by_id(ssh, id)) == NULL) { 2352 debug_f("x11 channel %d missing", id); 2353 } else { 2354 /* Detach X11 listener */ 2355 debug_f("detach x11 channel %d", id); 2356 channel_cancel_cleanup(ssh, id); 2357 if (c->ostate != CHAN_OUTPUT_CLOSED) 2358 chan_mark_dead(ssh, c); 2359 } 2360 } 2361 2362 static void 2363 session_close_single_x11(struct ssh *ssh, int id, void *arg) 2364 { 2365 Session *s; 2366 u_int i; 2367 2368 debug3_f("channel %d", id); 2369 channel_cancel_cleanup(ssh, id); 2370 if ((s = session_by_x11_channel(id)) == NULL) 2371 fatal_f("no x11 channel %d", id); 2372 for (i = 0; s->x11_chanids[i] != -1; i++) { 2373 debug_f("session %d: closing channel %d", 2374 s->self, s->x11_chanids[i]); 2375 /* 2376 * The channel "id" is already closing, but make sure we 2377 * close all of its siblings. 2378 */ 2379 if (s->x11_chanids[i] != id) 2380 session_close_x11(ssh, s->x11_chanids[i]); 2381 } 2382 free(s->x11_chanids); 2383 s->x11_chanids = NULL; 2384 free(s->display); 2385 s->display = NULL; 2386 free(s->auth_proto); 2387 s->auth_proto = NULL; 2388 free(s->auth_data); 2389 s->auth_data = NULL; 2390 free(s->auth_display); 2391 s->auth_display = NULL; 2392 } 2393 2394 static void 2395 session_exit_message(struct ssh *ssh, Session *s, int status) 2396 { 2397 Channel *c; 2398 int r; 2399 2400 if ((c = channel_lookup(ssh, s->chanid)) == NULL) 2401 fatal_f("session %d: no channel %d", s->self, s->chanid); 2402 debug_f("session %d channel %d pid %ld", 2403 s->self, s->chanid, (long)s->pid); 2404 2405 if (WIFEXITED(status)) { 2406 channel_request_start(ssh, s->chanid, "exit-status", 0); 2407 if ((r = sshpkt_put_u32(ssh, WEXITSTATUS(status))) != 0 || 2408 (r = sshpkt_send(ssh)) != 0) 2409 sshpkt_fatal(ssh, r, "%s: exit reply", __func__); 2410 } else if (WIFSIGNALED(status)) { 2411 channel_request_start(ssh, s->chanid, "exit-signal", 0); 2412 #ifndef WCOREDUMP 2413 # define WCOREDUMP(x) (0) 2414 #endif 2415 if ((r = sshpkt_put_cstring(ssh, sig2name(WTERMSIG(status)))) != 0 || 2416 (r = sshpkt_put_u8(ssh, WCOREDUMP(status)? 1 : 0)) != 0 || 2417 (r = sshpkt_put_cstring(ssh, "")) != 0 || 2418 (r = sshpkt_put_cstring(ssh, "")) != 0 || 2419 (r = sshpkt_send(ssh)) != 0) 2420 sshpkt_fatal(ssh, r, "%s: exit reply", __func__); 2421 } else { 2422 /* Some weird exit cause. Just exit. */ 2423 ssh_packet_disconnect(ssh, "wait returned status %04x.", status); 2424 } 2425 2426 /* disconnect channel */ 2427 debug_f("release channel %d", s->chanid); 2428 2429 /* 2430 * Adjust cleanup callback attachment to send close messages when 2431 * the channel gets EOF. The session will be then be closed 2432 * by session_close_by_channel when the child sessions close their fds. 2433 */ 2434 channel_register_cleanup(ssh, c->self, session_close_by_channel, 1); 2435 2436 /* 2437 * emulate a write failure with 'chan_write_failed', nobody will be 2438 * interested in data we write. 2439 * Note that we must not call 'chan_read_failed', since there could 2440 * be some more data waiting in the pipe. 2441 */ 2442 if (c->ostate != CHAN_OUTPUT_CLOSED) 2443 chan_write_failed(ssh, c); 2444 } 2445 2446 void 2447 session_close(struct ssh *ssh, Session *s) 2448 { 2449 u_int i; 2450 2451 verbose("Close session: user %s from %.200s port %d id %d", 2452 s->pw->pw_name, 2453 ssh_remote_ipaddr(ssh), 2454 ssh_remote_port(ssh), 2455 s->self); 2456 2457 if (s->ttyfd != -1) 2458 session_pty_cleanup(s); 2459 free(s->term); 2460 free(s->display); 2461 free(s->x11_chanids); 2462 free(s->auth_display); 2463 free(s->auth_data); 2464 free(s->auth_proto); 2465 free(s->subsys); 2466 if (s->env != NULL) { 2467 for (i = 0; i < s->num_env; i++) { 2468 free(s->env[i].name); 2469 free(s->env[i].val); 2470 } 2471 free(s->env); 2472 } 2473 session_proctitle(s); 2474 session_unused(s->self); 2475 } 2476 2477 void 2478 session_close_by_pid(struct ssh *ssh, pid_t pid, int status) 2479 { 2480 Session *s = session_by_pid(pid); 2481 if (s == NULL) { 2482 debug_f("no session for pid %ld", (long)pid); 2483 return; 2484 } 2485 if (s->chanid != -1) 2486 session_exit_message(ssh, s, status); 2487 if (s->ttyfd != -1) 2488 session_pty_cleanup(s); 2489 s->pid = 0; 2490 } 2491 2492 /* 2493 * this is called when a channel dies before 2494 * the session 'child' itself dies 2495 */ 2496 void 2497 session_close_by_channel(struct ssh *ssh, int id, void *arg) 2498 { 2499 Session *s = session_by_channel(id); 2500 u_int i; 2501 2502 if (s == NULL) { 2503 debug_f("no session for id %d", id); 2504 return; 2505 } 2506 debug_f("channel %d child %ld", id, (long)s->pid); 2507 if (s->pid != 0) { 2508 debug_f("channel %d: has child, ttyfd %d", id, s->ttyfd); 2509 /* 2510 * delay detach of session, but release pty, since 2511 * the fd's to the child are already closed 2512 */ 2513 if (s->ttyfd != -1) 2514 session_pty_cleanup(s); 2515 return; 2516 } 2517 /* detach by removing callback */ 2518 channel_cancel_cleanup(ssh, s->chanid); 2519 2520 /* Close any X11 listeners associated with this session */ 2521 if (s->x11_chanids != NULL) { 2522 for (i = 0; s->x11_chanids[i] != -1; i++) { 2523 session_close_x11(ssh, s->x11_chanids[i]); 2524 s->x11_chanids[i] = -1; 2525 } 2526 } 2527 2528 s->chanid = -1; 2529 session_close(ssh, s); 2530 } 2531 2532 void 2533 session_destroy_all(struct ssh *ssh, void (*closefunc)(Session *)) 2534 { 2535 int i; 2536 for (i = 0; i < sessions_nalloc; i++) { 2537 Session *s = &sessions[i]; 2538 if (s->used) { 2539 if (closefunc != NULL) 2540 closefunc(s); 2541 else 2542 session_close(ssh, s); 2543 } 2544 } 2545 } 2546 2547 static char * 2548 session_tty_list(void) 2549 { 2550 static char buf[1024]; 2551 int i; 2552 char *cp; 2553 2554 buf[0] = '\0'; 2555 for (i = 0; i < sessions_nalloc; i++) { 2556 Session *s = &sessions[i]; 2557 if (s->used && s->ttyfd != -1) { 2558 2559 if (strncmp(s->tty, "/dev/", 5) != 0) { 2560 cp = strrchr(s->tty, '/'); 2561 cp = (cp == NULL) ? s->tty : cp + 1; 2562 } else 2563 cp = s->tty + 5; 2564 2565 if (buf[0] != '\0') 2566 strlcat(buf, ",", sizeof buf); 2567 strlcat(buf, cp, sizeof buf); 2568 } 2569 } 2570 if (buf[0] == '\0') 2571 strlcpy(buf, "notty", sizeof buf); 2572 return buf; 2573 } 2574 2575 void 2576 session_proctitle(Session *s) 2577 { 2578 if (s->pw == NULL) 2579 error("no user for session %d", s->self); 2580 else 2581 setproctitle("%s@%s", s->pw->pw_name, session_tty_list()); 2582 } 2583 2584 int 2585 session_setup_x11fwd(struct ssh *ssh, Session *s) 2586 { 2587 struct stat st; 2588 char display[512], auth_display[512]; 2589 char hostname[NI_MAXHOST]; 2590 u_int i; 2591 2592 if (!auth_opts->permit_x11_forwarding_flag) { 2593 ssh_packet_send_debug(ssh, "X11 forwarding disabled by key options."); 2594 return 0; 2595 } 2596 if (!options.x11_forwarding) { 2597 debug("X11 forwarding disabled in server configuration file."); 2598 return 0; 2599 } 2600 if (options.xauth_location == NULL || 2601 (stat(options.xauth_location, &st) == -1)) { 2602 ssh_packet_send_debug(ssh, "No xauth program; cannot forward X11."); 2603 return 0; 2604 } 2605 if (s->display != NULL) { 2606 debug("X11 display already set."); 2607 return 0; 2608 } 2609 if (x11_create_display_inet(ssh, options.x11_display_offset, 2610 options.x11_use_localhost, s->single_connection, 2611 &s->display_number, &s->x11_chanids) == -1) { 2612 debug("x11_create_display_inet failed."); 2613 return 0; 2614 } 2615 for (i = 0; s->x11_chanids[i] != -1; i++) { 2616 channel_register_cleanup(ssh, s->x11_chanids[i], 2617 session_close_single_x11, 0); 2618 } 2619 2620 /* Set up a suitable value for the DISPLAY variable. */ 2621 if (gethostname(hostname, sizeof(hostname)) == -1) 2622 fatal("gethostname: %.100s", strerror(errno)); 2623 /* 2624 * auth_display must be used as the displayname when the 2625 * authorization entry is added with xauth(1). This will be 2626 * different than the DISPLAY string for localhost displays. 2627 */ 2628 if (options.x11_use_localhost) { 2629 snprintf(display, sizeof display, "localhost:%u.%u", 2630 s->display_number, s->screen); 2631 snprintf(auth_display, sizeof auth_display, "unix:%u.%u", 2632 s->display_number, s->screen); 2633 s->display = xstrdup(display); 2634 s->auth_display = xstrdup(auth_display); 2635 } else { 2636 #ifdef IPADDR_IN_DISPLAY 2637 struct hostent *he; 2638 struct in_addr my_addr; 2639 2640 he = gethostbyname(hostname); 2641 if (he == NULL) { 2642 error("Can't get IP address for X11 DISPLAY."); 2643 ssh_packet_send_debug(ssh, "Can't get IP address for X11 DISPLAY."); 2644 return 0; 2645 } 2646 memcpy(&my_addr, he->h_addr_list[0], sizeof(struct in_addr)); 2647 snprintf(display, sizeof display, "%.50s:%u.%u", inet_ntoa(my_addr), 2648 s->display_number, s->screen); 2649 #else 2650 snprintf(display, sizeof display, "%.400s:%u.%u", hostname, 2651 s->display_number, s->screen); 2652 #endif 2653 s->display = xstrdup(display); 2654 s->auth_display = xstrdup(display); 2655 } 2656 2657 return 1; 2658 } 2659 2660 static void 2661 do_authenticated2(struct ssh *ssh, Authctxt *authctxt) 2662 { 2663 server_loop2(ssh, authctxt); 2664 } 2665 2666 void 2667 do_cleanup(struct ssh *ssh, Authctxt *authctxt) 2668 { 2669 static int called = 0; 2670 2671 debug("do_cleanup"); 2672 2673 /* no cleanup if we're in the child for login shell */ 2674 if (is_child) 2675 return; 2676 2677 /* avoid double cleanup */ 2678 if (called) 2679 return; 2680 called = 1; 2681 2682 if (authctxt == NULL) 2683 return; 2684 2685 #ifdef USE_PAM 2686 if (options.use_pam) { 2687 sshpam_cleanup(); 2688 sshpam_thread_cleanup(); 2689 } 2690 #endif 2691 2692 if (!authctxt->authenticated) 2693 return; 2694 2695 #ifdef KRB5 2696 if (options.kerberos_ticket_cleanup && 2697 authctxt->krb5_ctx) 2698 krb5_cleanup_proc(authctxt); 2699 #endif 2700 2701 #ifdef GSSAPI 2702 if (options.gss_cleanup_creds) 2703 ssh_gssapi_cleanup_creds(); 2704 #endif 2705 2706 /* remove agent socket */ 2707 auth_sock_cleanup_proc(authctxt->pw); 2708 2709 /* remove userauth info */ 2710 if (auth_info_file != NULL) { 2711 temporarily_use_uid(authctxt->pw); 2712 unlink(auth_info_file); 2713 restore_uid(); 2714 free(auth_info_file); 2715 auth_info_file = NULL; 2716 } 2717 2718 /* 2719 * Cleanup ptys/utmp only if privsep is disabled, 2720 * or if running in monitor. 2721 */ 2722 if (!use_privsep || mm_is_monitor()) 2723 session_destroy_all(ssh, session_pty_cleanup2); 2724 } 2725 2726 /* Return a name for the remote host that fits inside utmp_size */ 2727 2728 const char * 2729 session_get_remote_name_or_ip(struct ssh *ssh, u_int utmp_size, int use_dns) 2730 { 2731 const char *remote = ""; 2732 2733 if (utmp_size > 0) 2734 remote = auth_get_canonical_hostname(ssh, use_dns); 2735 if (utmp_size == 0 || strlen(remote) > utmp_size) 2736 remote = ssh_remote_ipaddr(ssh); 2737 return remote; 2738 } 2739 2740