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 __RCSID("$FreeBSD$"); 38 39 #include <sys/types.h> 40 #include <sys/param.h> 41 #ifdef HAVE_SYS_STAT_H 42 # include <sys/stat.h> 43 #endif 44 #include <sys/socket.h> 45 #include <sys/un.h> 46 #include <sys/wait.h> 47 48 #include <arpa/inet.h> 49 50 #include <ctype.h> 51 #include <errno.h> 52 #include <fcntl.h> 53 #include <grp.h> 54 #include <netdb.h> 55 #ifdef HAVE_PATHS_H 56 #include <paths.h> 57 #endif 58 #include <pwd.h> 59 #include <signal.h> 60 #include <stdio.h> 61 #include <stdlib.h> 62 #include <string.h> 63 #include <stdarg.h> 64 #include <unistd.h> 65 #include <limits.h> 66 67 #include "openbsd-compat/sys-queue.h" 68 #include "xmalloc.h" 69 #include "ssh.h" 70 #include "ssh2.h" 71 #include "sshpty.h" 72 #include "packet.h" 73 #include "sshbuf.h" 74 #include "ssherr.h" 75 #include "match.h" 76 #include "uidswap.h" 77 #include "compat.h" 78 #include "channels.h" 79 #include "sshkey.h" 80 #include "cipher.h" 81 #ifdef GSSAPI 82 #include "ssh-gss.h" 83 #endif 84 #include "hostfile.h" 85 #include "auth.h" 86 #include "auth-options.h" 87 #include "authfd.h" 88 #include "pathnames.h" 89 #include "log.h" 90 #include "misc.h" 91 #include "servconf.h" 92 #include "sshlogin.h" 93 #include "serverloop.h" 94 #include "canohost.h" 95 #include "session.h" 96 #include "kex.h" 97 #include "monitor_wrap.h" 98 #include "sftp.h" 99 #include "atomicio.h" 100 101 #if defined(KRB5) && defined(USE_AFS) 102 #include <kafs.h> 103 #endif 104 105 #ifdef WITH_SELINUX 106 #include <selinux/selinux.h> 107 #endif 108 109 #define IS_INTERNAL_SFTP(c) \ 110 (!strncmp(c, INTERNAL_SFTP_NAME, sizeof(INTERNAL_SFTP_NAME) - 1) && \ 111 (c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\0' || \ 112 c[sizeof(INTERNAL_SFTP_NAME) - 1] == ' ' || \ 113 c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\t')) 114 115 /* func */ 116 117 Session *session_new(void); 118 void session_set_fds(struct ssh *, Session *, int, int, int, int, int); 119 void session_pty_cleanup(Session *); 120 void session_proctitle(Session *); 121 int session_setup_x11fwd(struct ssh *, Session *); 122 int do_exec_pty(struct ssh *, Session *, const char *); 123 int do_exec_no_pty(struct ssh *, Session *, const char *); 124 int do_exec(struct ssh *, Session *, const char *); 125 void do_login(struct ssh *, Session *, const char *); 126 void do_child(struct ssh *, Session *, const char *); 127 void do_motd(void); 128 int check_quietlogin(Session *, const char *); 129 130 static void do_authenticated2(struct ssh *, Authctxt *); 131 132 static int session_pty_req(struct ssh *, Session *); 133 134 /* import */ 135 extern ServerOptions options; 136 extern char *__progname; 137 extern int debug_flag; 138 extern u_int utmp_len; 139 extern int startup_pipe; 140 extern void destroy_sensitive_data(void); 141 extern struct sshbuf *loginmsg; 142 extern struct sshauthopt *auth_opts; 143 extern char *tun_fwd_ifnames; /* serverloop.c */ 144 145 /* original command from peer. */ 146 const char *original_command = NULL; 147 148 /* data */ 149 static int sessions_first_unused = -1; 150 static int sessions_nalloc = 0; 151 static Session *sessions = NULL; 152 153 #define SUBSYSTEM_NONE 0 154 #define SUBSYSTEM_EXT 1 155 #define SUBSYSTEM_INT_SFTP 2 156 #define SUBSYSTEM_INT_SFTP_ERROR 3 157 158 #ifdef HAVE_LOGIN_CAP 159 login_cap_t *lc; 160 #endif 161 162 static int is_child = 0; 163 static int in_chroot = 0; 164 165 /* File containing userauth info, if ExposeAuthInfo set */ 166 static char *auth_info_file = NULL; 167 168 /* Name and directory of socket for authentication agent forwarding. */ 169 static char *auth_sock_name = NULL; 170 static char *auth_sock_dir = NULL; 171 172 /* removes the agent forwarding socket */ 173 174 static void 175 auth_sock_cleanup_proc(struct passwd *pw) 176 { 177 if (auth_sock_name != NULL) { 178 temporarily_use_uid(pw); 179 unlink(auth_sock_name); 180 rmdir(auth_sock_dir); 181 auth_sock_name = NULL; 182 restore_uid(); 183 } 184 } 185 186 static int 187 auth_input_request_forwarding(struct ssh *ssh, struct passwd * pw) 188 { 189 Channel *nc; 190 int sock = -1; 191 192 if (auth_sock_name != NULL) { 193 error("authentication forwarding requested twice."); 194 return 0; 195 } 196 197 /* Temporarily drop privileged uid for mkdir/bind. */ 198 temporarily_use_uid(pw); 199 200 /* Allocate a buffer for the socket name, and format the name. */ 201 auth_sock_dir = xstrdup("/tmp/ssh-XXXXXXXXXX"); 202 203 /* Create private directory for socket */ 204 if (mkdtemp(auth_sock_dir) == NULL) { 205 ssh_packet_send_debug(ssh, "Agent forwarding disabled: " 206 "mkdtemp() failed: %.100s", strerror(errno)); 207 restore_uid(); 208 free(auth_sock_dir); 209 auth_sock_dir = NULL; 210 goto authsock_err; 211 } 212 213 xasprintf(&auth_sock_name, "%s/agent.%ld", 214 auth_sock_dir, (long) getpid()); 215 216 /* Start a Unix listener on auth_sock_name. */ 217 sock = unix_listener(auth_sock_name, SSH_LISTEN_BACKLOG, 0); 218 219 /* Restore the privileged uid. */ 220 restore_uid(); 221 222 /* Check for socket/bind/listen failure. */ 223 if (sock < 0) 224 goto authsock_err; 225 226 /* Allocate a channel for the authentication agent socket. */ 227 nc = channel_new(ssh, "auth socket", 228 SSH_CHANNEL_AUTH_SOCKET, sock, sock, -1, 229 CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 230 0, "auth socket", 1); 231 nc->path = xstrdup(auth_sock_name); 232 return 1; 233 234 authsock_err: 235 free(auth_sock_name); 236 if (auth_sock_dir != NULL) { 237 temporarily_use_uid(pw); 238 rmdir(auth_sock_dir); 239 restore_uid(); 240 free(auth_sock_dir); 241 } 242 if (sock != -1) 243 close(sock); 244 auth_sock_name = NULL; 245 auth_sock_dir = NULL; 246 return 0; 247 } 248 249 static void 250 display_loginmsg(void) 251 { 252 int r; 253 254 if (sshbuf_len(loginmsg) == 0) 255 return; 256 if ((r = sshbuf_put_u8(loginmsg, 0)) != 0) 257 fatal_fr(r, "sshbuf_put_u8"); 258 printf("%s", (char *)sshbuf_ptr(loginmsg)); 259 sshbuf_reset(loginmsg); 260 } 261 262 static void 263 prepare_auth_info_file(struct passwd *pw, struct sshbuf *info) 264 { 265 int fd = -1, success = 0; 266 267 if (!options.expose_userauth_info || info == NULL) 268 return; 269 270 temporarily_use_uid(pw); 271 auth_info_file = xstrdup("/tmp/sshauth.XXXXXXXXXXXXXXX"); 272 if ((fd = mkstemp(auth_info_file)) == -1) { 273 error_f("mkstemp: %s", strerror(errno)); 274 goto out; 275 } 276 if (atomicio(vwrite, fd, sshbuf_mutable_ptr(info), 277 sshbuf_len(info)) != sshbuf_len(info)) { 278 error_f("write: %s", strerror(errno)); 279 goto out; 280 } 281 if (close(fd) != 0) { 282 error_f("close: %s", strerror(errno)); 283 goto out; 284 } 285 success = 1; 286 out: 287 if (!success) { 288 if (fd != -1) 289 close(fd); 290 free(auth_info_file); 291 auth_info_file = NULL; 292 } 293 restore_uid(); 294 } 295 296 static void 297 set_fwdpermit_from_authopts(struct ssh *ssh, const struct sshauthopt *opts) 298 { 299 char *tmp, *cp, *host; 300 int port; 301 size_t i; 302 303 if ((options.allow_tcp_forwarding & FORWARD_LOCAL) != 0) { 304 channel_clear_permission(ssh, FORWARD_USER, FORWARD_LOCAL); 305 for (i = 0; i < auth_opts->npermitopen; i++) { 306 tmp = cp = xstrdup(auth_opts->permitopen[i]); 307 /* This shouldn't fail as it has already been checked */ 308 if ((host = hpdelim(&cp)) == NULL) 309 fatal_f("internal error: hpdelim"); 310 host = cleanhostname(host); 311 if (cp == NULL || (port = permitopen_port(cp)) < 0) 312 fatal_f("internal error: permitopen port"); 313 channel_add_permission(ssh, 314 FORWARD_USER, FORWARD_LOCAL, host, port); 315 free(tmp); 316 } 317 } 318 if ((options.allow_tcp_forwarding & FORWARD_REMOTE) != 0) { 319 channel_clear_permission(ssh, FORWARD_USER, FORWARD_REMOTE); 320 for (i = 0; i < auth_opts->npermitlisten; i++) { 321 tmp = cp = xstrdup(auth_opts->permitlisten[i]); 322 /* This shouldn't fail as it has already been checked */ 323 if ((host = hpdelim(&cp)) == NULL) 324 fatal_f("internal error: hpdelim"); 325 host = cleanhostname(host); 326 if (cp == NULL || (port = permitopen_port(cp)) < 0) 327 fatal_f("internal error: permitlisten port"); 328 channel_add_permission(ssh, 329 FORWARD_USER, FORWARD_REMOTE, host, port); 330 free(tmp); 331 } 332 } 333 } 334 335 void 336 do_authenticated(struct ssh *ssh, Authctxt *authctxt) 337 { 338 setproctitle("%s", authctxt->pw->pw_name); 339 340 auth_log_authopts("active", auth_opts, 0); 341 342 /* setup the channel layer */ 343 /* XXX - streamlocal? */ 344 set_fwdpermit_from_authopts(ssh, auth_opts); 345 346 if (!auth_opts->permit_port_forwarding_flag || 347 options.disable_forwarding) { 348 channel_disable_admin(ssh, FORWARD_LOCAL); 349 channel_disable_admin(ssh, FORWARD_REMOTE); 350 } else { 351 if ((options.allow_tcp_forwarding & FORWARD_LOCAL) == 0) 352 channel_disable_admin(ssh, FORWARD_LOCAL); 353 else 354 channel_permit_all(ssh, FORWARD_LOCAL); 355 if ((options.allow_tcp_forwarding & FORWARD_REMOTE) == 0) 356 channel_disable_admin(ssh, FORWARD_REMOTE); 357 else 358 channel_permit_all(ssh, FORWARD_REMOTE); 359 } 360 auth_debug_send(ssh); 361 362 prepare_auth_info_file(authctxt->pw, authctxt->session_info); 363 364 do_authenticated2(ssh, authctxt); 365 366 do_cleanup(ssh, authctxt); 367 } 368 369 /* Check untrusted xauth strings for metacharacters */ 370 static int 371 xauth_valid_string(const char *s) 372 { 373 size_t i; 374 375 for (i = 0; s[i] != '\0'; i++) { 376 if (!isalnum((u_char)s[i]) && 377 s[i] != '.' && s[i] != ':' && s[i] != '/' && 378 s[i] != '-' && s[i] != '_') 379 return 0; 380 } 381 return 1; 382 } 383 384 #define USE_PIPES 1 385 /* 386 * This is called to fork and execute a command when we have no tty. This 387 * will call do_child from the child, and server_loop from the parent after 388 * setting up file descriptors and such. 389 */ 390 int 391 do_exec_no_pty(struct ssh *ssh, Session *s, const char *command) 392 { 393 pid_t pid; 394 #ifdef USE_PIPES 395 int pin[2], pout[2], perr[2]; 396 397 if (s == NULL) 398 fatal("do_exec_no_pty: no session"); 399 400 /* Allocate pipes for communicating with the program. */ 401 if (pipe(pin) == -1) { 402 error_f("pipe in: %.100s", strerror(errno)); 403 return -1; 404 } 405 if (pipe(pout) == -1) { 406 error_f("pipe out: %.100s", strerror(errno)); 407 close(pin[0]); 408 close(pin[1]); 409 return -1; 410 } 411 if (pipe(perr) == -1) { 412 error_f("pipe err: %.100s", strerror(errno)); 413 close(pin[0]); 414 close(pin[1]); 415 close(pout[0]); 416 close(pout[1]); 417 return -1; 418 } 419 #else 420 int inout[2], err[2]; 421 422 if (s == NULL) 423 fatal("do_exec_no_pty: no session"); 424 425 /* Uses socket pairs to communicate with the program. */ 426 if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) == -1) { 427 error_f("socketpair #1: %.100s", strerror(errno)); 428 return -1; 429 } 430 if (socketpair(AF_UNIX, SOCK_STREAM, 0, err) == -1) { 431 error_f("socketpair #2: %.100s", strerror(errno)); 432 close(inout[0]); 433 close(inout[1]); 434 return -1; 435 } 436 #endif 437 438 session_proctitle(s); 439 440 /* Fork the child. */ 441 switch ((pid = fork())) { 442 case -1: 443 error_f("fork: %.100s", strerror(errno)); 444 #ifdef USE_PIPES 445 close(pin[0]); 446 close(pin[1]); 447 close(pout[0]); 448 close(pout[1]); 449 close(perr[0]); 450 close(perr[1]); 451 #else 452 close(inout[0]); 453 close(inout[1]); 454 close(err[0]); 455 close(err[1]); 456 #endif 457 return -1; 458 case 0: 459 is_child = 1; 460 461 /* 462 * Create a new session and process group since the 4.4BSD 463 * setlogin() affects the entire process group. 464 */ 465 if (setsid() == -1) 466 error("setsid failed: %.100s", strerror(errno)); 467 468 #ifdef USE_PIPES 469 /* 470 * Redirect stdin. We close the parent side of the socket 471 * pair, and make the child side the standard input. 472 */ 473 close(pin[1]); 474 if (dup2(pin[0], 0) == -1) 475 perror("dup2 stdin"); 476 close(pin[0]); 477 478 /* Redirect stdout. */ 479 close(pout[0]); 480 if (dup2(pout[1], 1) == -1) 481 perror("dup2 stdout"); 482 close(pout[1]); 483 484 /* Redirect stderr. */ 485 close(perr[0]); 486 if (dup2(perr[1], 2) == -1) 487 perror("dup2 stderr"); 488 close(perr[1]); 489 #else 490 /* 491 * Redirect stdin, stdout, and stderr. Stdin and stdout will 492 * use the same socket, as some programs (particularly rdist) 493 * seem to depend on it. 494 */ 495 close(inout[1]); 496 close(err[1]); 497 if (dup2(inout[0], 0) == -1) /* stdin */ 498 perror("dup2 stdin"); 499 if (dup2(inout[0], 1) == -1) /* stdout (same as stdin) */ 500 perror("dup2 stdout"); 501 close(inout[0]); 502 if (dup2(err[0], 2) == -1) /* stderr */ 503 perror("dup2 stderr"); 504 close(err[0]); 505 #endif 506 507 /* Do processing for the child (exec command etc). */ 508 do_child(ssh, s, command); 509 /* NOTREACHED */ 510 default: 511 break; 512 } 513 514 #ifdef HAVE_CYGWIN 515 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); 516 #endif 517 518 s->pid = pid; 519 /* Set interactive/non-interactive mode. */ 520 ssh_packet_set_interactive(ssh, s->display != NULL, 521 options.ip_qos_interactive, options.ip_qos_bulk); 522 523 /* 524 * Clear loginmsg, since it's the child's responsibility to display 525 * it to the user, otherwise multiple sessions may accumulate 526 * multiple copies of the login messages. 527 */ 528 sshbuf_reset(loginmsg); 529 530 #ifdef USE_PIPES 531 /* We are the parent. Close the child sides of the pipes. */ 532 close(pin[0]); 533 close(pout[1]); 534 close(perr[1]); 535 536 session_set_fds(ssh, s, pin[1], pout[0], perr[0], 537 s->is_subsystem, 0); 538 #else 539 /* We are the parent. Close the child sides of the socket pairs. */ 540 close(inout[0]); 541 close(err[0]); 542 543 /* 544 * Enter the interactive session. Note: server_loop must be able to 545 * handle the case that fdin and fdout are the same. 546 */ 547 session_set_fds(ssh, s, inout[1], inout[1], err[1], 548 s->is_subsystem, 0); 549 #endif 550 return 0; 551 } 552 553 /* 554 * This is called to fork and execute a command when we have a tty. This 555 * will call do_child from the child, and server_loop from the parent after 556 * setting up file descriptors, controlling tty, updating wtmp, utmp, 557 * lastlog, and other such operations. 558 */ 559 int 560 do_exec_pty(struct ssh *ssh, Session *s, const char *command) 561 { 562 int fdout, ptyfd, ttyfd, ptymaster; 563 pid_t pid; 564 565 if (s == NULL) 566 fatal("do_exec_pty: no session"); 567 ptyfd = s->ptyfd; 568 ttyfd = s->ttyfd; 569 570 /* 571 * Create another descriptor of the pty master side for use as the 572 * standard input. We could use the original descriptor, but this 573 * simplifies code in server_loop. The descriptor is bidirectional. 574 * Do this before forking (and cleanup in the child) so as to 575 * detect and gracefully fail out-of-fd conditions. 576 */ 577 if ((fdout = dup(ptyfd)) == -1) { 578 error_f("dup #1: %s", strerror(errno)); 579 close(ttyfd); 580 close(ptyfd); 581 return -1; 582 } 583 /* we keep a reference to the pty master */ 584 if ((ptymaster = dup(ptyfd)) == -1) { 585 error_f("dup #2: %s", strerror(errno)); 586 close(ttyfd); 587 close(ptyfd); 588 close(fdout); 589 return -1; 590 } 591 592 /* Fork the child. */ 593 switch ((pid = fork())) { 594 case -1: 595 error_f("fork: %.100s", strerror(errno)); 596 close(fdout); 597 close(ptymaster); 598 close(ttyfd); 599 close(ptyfd); 600 return -1; 601 case 0: 602 is_child = 1; 603 604 close(fdout); 605 close(ptymaster); 606 607 /* Close the master side of the pseudo tty. */ 608 close(ptyfd); 609 610 /* Make the pseudo tty our controlling tty. */ 611 pty_make_controlling_tty(&ttyfd, s->tty); 612 613 /* Redirect stdin/stdout/stderr from the pseudo tty. */ 614 if (dup2(ttyfd, 0) == -1) 615 error("dup2 stdin: %s", strerror(errno)); 616 if (dup2(ttyfd, 1) == -1) 617 error("dup2 stdout: %s", strerror(errno)); 618 if (dup2(ttyfd, 2) == -1) 619 error("dup2 stderr: %s", strerror(errno)); 620 621 /* Close the extra descriptor for the pseudo tty. */ 622 close(ttyfd); 623 624 /* record login, etc. similar to login(1) */ 625 #ifndef HAVE_OSF_SIA 626 do_login(ssh, s, command); 627 #endif 628 /* 629 * Do common processing for the child, such as execing 630 * the command. 631 */ 632 do_child(ssh, s, command); 633 /* NOTREACHED */ 634 default: 635 break; 636 } 637 638 #ifdef HAVE_CYGWIN 639 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); 640 #endif 641 642 s->pid = pid; 643 644 /* Parent. Close the slave side of the pseudo tty. */ 645 close(ttyfd); 646 647 /* Enter interactive session. */ 648 s->ptymaster = ptymaster; 649 ssh_packet_set_interactive(ssh, 1, 650 options.ip_qos_interactive, options.ip_qos_bulk); 651 session_set_fds(ssh, s, ptyfd, fdout, -1, 1, 1); 652 return 0; 653 } 654 655 /* 656 * This is called to fork and execute a command. If another command is 657 * to be forced, execute that instead. 658 */ 659 int 660 do_exec(struct ssh *ssh, Session *s, const char *command) 661 { 662 int ret; 663 const char *forced = NULL, *tty = NULL; 664 char session_type[1024]; 665 666 if (options.adm_forced_command) { 667 original_command = command; 668 command = options.adm_forced_command; 669 forced = "(config)"; 670 } else if (auth_opts->force_command != NULL) { 671 original_command = command; 672 command = auth_opts->force_command; 673 forced = "(key-option)"; 674 } 675 s->forced = 0; 676 if (forced != NULL) { 677 s->forced = 1; 678 if (IS_INTERNAL_SFTP(command)) { 679 s->is_subsystem = s->is_subsystem ? 680 SUBSYSTEM_INT_SFTP : SUBSYSTEM_INT_SFTP_ERROR; 681 } else if (s->is_subsystem) 682 s->is_subsystem = SUBSYSTEM_EXT; 683 snprintf(session_type, sizeof(session_type), 684 "forced-command %s '%.900s'", forced, command); 685 } else if (s->is_subsystem) { 686 snprintf(session_type, sizeof(session_type), 687 "subsystem '%.900s'", s->subsys); 688 } else if (command == NULL) { 689 snprintf(session_type, sizeof(session_type), "shell"); 690 } else { 691 /* NB. we don't log unforced commands to preserve privacy */ 692 snprintf(session_type, sizeof(session_type), "command"); 693 } 694 695 if (s->ttyfd != -1) { 696 tty = s->tty; 697 if (strncmp(tty, "/dev/", 5) == 0) 698 tty += 5; 699 } 700 701 verbose("Starting session: %s%s%s for %s from %.200s port %d id %d", 702 session_type, 703 tty == NULL ? "" : " on ", 704 tty == NULL ? "" : tty, 705 s->pw->pw_name, 706 ssh_remote_ipaddr(ssh), 707 ssh_remote_port(ssh), 708 s->self); 709 710 #ifdef SSH_AUDIT_EVENTS 711 if (command != NULL) 712 PRIVSEP(audit_run_command(command)); 713 else if (s->ttyfd == -1) { 714 char *shell = s->pw->pw_shell; 715 716 if (shell[0] == '\0') /* empty shell means /bin/sh */ 717 shell =_PATH_BSHELL; 718 PRIVSEP(audit_run_command(shell)); 719 } 720 #endif 721 if (s->ttyfd != -1) 722 ret = do_exec_pty(ssh, s, command); 723 else 724 ret = do_exec_no_pty(ssh, s, command); 725 726 original_command = NULL; 727 728 /* 729 * Clear loginmsg: it's the child's responsibility to display 730 * it to the user, otherwise multiple sessions may accumulate 731 * multiple copies of the login messages. 732 */ 733 sshbuf_reset(loginmsg); 734 735 return ret; 736 } 737 738 /* administrative, login(1)-like work */ 739 void 740 do_login(struct ssh *ssh, Session *s, const char *command) 741 { 742 socklen_t fromlen; 743 struct sockaddr_storage from; 744 struct passwd * pw = s->pw; 745 pid_t pid = getpid(); 746 747 /* 748 * Get IP address of client. If the connection is not a socket, let 749 * the address be 0.0.0.0. 750 */ 751 memset(&from, 0, sizeof(from)); 752 fromlen = sizeof(from); 753 if (ssh_packet_connection_is_on_socket(ssh)) { 754 if (getpeername(ssh_packet_get_connection_in(ssh), 755 (struct sockaddr *)&from, &fromlen) == -1) { 756 debug("getpeername: %.100s", strerror(errno)); 757 cleanup_exit(255); 758 } 759 } 760 761 /* Record that there was a login on that tty from the remote host. */ 762 if (!use_privsep) 763 record_login(pid, s->tty, pw->pw_name, pw->pw_uid, 764 session_get_remote_name_or_ip(ssh, utmp_len, 765 options.use_dns), 766 (struct sockaddr *)&from, fromlen); 767 768 #ifdef USE_PAM 769 /* 770 * If password change is needed, do it now. 771 * This needs to occur before the ~/.hushlogin check. 772 */ 773 if (options.use_pam && !use_privsep && s->authctxt->force_pwchange) { 774 display_loginmsg(); 775 do_pam_chauthtok(); 776 s->authctxt->force_pwchange = 0; 777 /* XXX - signal [net] parent to enable forwardings */ 778 } 779 #endif 780 781 if (check_quietlogin(s, command)) 782 return; 783 784 display_loginmsg(); 785 786 do_motd(); 787 } 788 789 /* 790 * Display the message of the day. 791 */ 792 void 793 do_motd(void) 794 { 795 FILE *f; 796 char buf[256]; 797 798 if (options.print_motd) { 799 #ifdef HAVE_LOGIN_CAP 800 f = fopen(login_getcapstr(lc, "welcome", "/etc/motd", 801 "/etc/motd"), "r"); 802 #else 803 f = fopen("/etc/motd", "r"); 804 #endif 805 if (f) { 806 while (fgets(buf, sizeof(buf), f)) 807 fputs(buf, stdout); 808 fclose(f); 809 } 810 } 811 } 812 813 814 /* 815 * Check for quiet login, either .hushlogin or command given. 816 */ 817 int 818 check_quietlogin(Session *s, const char *command) 819 { 820 char buf[256]; 821 struct passwd *pw = s->pw; 822 struct stat st; 823 824 /* Return 1 if .hushlogin exists or a command given. */ 825 if (command != NULL) 826 return 1; 827 snprintf(buf, sizeof(buf), "%.200s/.hushlogin", pw->pw_dir); 828 #ifdef HAVE_LOGIN_CAP 829 if (login_getcapbool(lc, "hushlogin", 0) || stat(buf, &st) >= 0) 830 return 1; 831 #else 832 if (stat(buf, &st) >= 0) 833 return 1; 834 #endif 835 return 0; 836 } 837 838 /* 839 * Reads environment variables from the given file and adds/overrides them 840 * into the environment. If the file does not exist, this does nothing. 841 * Otherwise, it must consist of empty lines, comments (line starts with '#') 842 * and assignments of the form name=value. No other forms are allowed. 843 * If allowlist is not NULL, then it is interpreted as a pattern list and 844 * only variable names that match it will be accepted. 845 */ 846 static void 847 read_environment_file(char ***env, u_int *envsize, 848 const char *filename, const char *allowlist) 849 { 850 FILE *f; 851 char *line = NULL, *cp, *value; 852 size_t linesize = 0; 853 u_int lineno = 0; 854 855 f = fopen(filename, "r"); 856 if (!f) 857 return; 858 859 while (getline(&line, &linesize, f) != -1) { 860 if (++lineno > 1000) 861 fatal("Too many lines in environment file %s", filename); 862 for (cp = line; *cp == ' ' || *cp == '\t'; cp++) 863 ; 864 if (!*cp || *cp == '#' || *cp == '\n') 865 continue; 866 867 cp[strcspn(cp, "\n")] = '\0'; 868 869 value = strchr(cp, '='); 870 if (value == NULL) { 871 fprintf(stderr, "Bad line %u in %.100s\n", lineno, 872 filename); 873 continue; 874 } 875 /* 876 * Replace the equals sign by nul, and advance value to 877 * the value string. 878 */ 879 *value = '\0'; 880 value++; 881 if (allowlist != NULL && 882 match_pattern_list(cp, allowlist, 0) != 1) 883 continue; 884 child_set_env(env, envsize, cp, value); 885 } 886 free(line); 887 fclose(f); 888 } 889 890 #ifdef HAVE_ETC_DEFAULT_LOGIN 891 /* 892 * Return named variable from specified environment, or NULL if not present. 893 */ 894 static char * 895 child_get_env(char **env, const char *name) 896 { 897 int i; 898 size_t len; 899 900 len = strlen(name); 901 for (i=0; env[i] != NULL; i++) 902 if (strncmp(name, env[i], len) == 0 && env[i][len] == '=') 903 return(env[i] + len + 1); 904 return NULL; 905 } 906 907 /* 908 * Read /etc/default/login. 909 * We pick up the PATH (or SUPATH for root) and UMASK. 910 */ 911 static void 912 read_etc_default_login(char ***env, u_int *envsize, uid_t uid) 913 { 914 char **tmpenv = NULL, *var; 915 u_int i, tmpenvsize = 0; 916 u_long mask; 917 918 /* 919 * We don't want to copy the whole file to the child's environment, 920 * so we use a temporary environment and copy the variables we're 921 * interested in. 922 */ 923 read_environment_file(&tmpenv, &tmpenvsize, "/etc/default/login", 924 options.permit_user_env_allowlist); 925 926 if (tmpenv == NULL) 927 return; 928 929 if (uid == 0) 930 var = child_get_env(tmpenv, "SUPATH"); 931 else 932 var = child_get_env(tmpenv, "PATH"); 933 if (var != NULL) 934 child_set_env(env, envsize, "PATH", var); 935 936 if ((var = child_get_env(tmpenv, "UMASK")) != NULL) 937 if (sscanf(var, "%5lo", &mask) == 1) 938 umask((mode_t)mask); 939 940 for (i = 0; tmpenv[i] != NULL; i++) 941 free(tmpenv[i]); 942 free(tmpenv); 943 } 944 #endif /* HAVE_ETC_DEFAULT_LOGIN */ 945 946 #if defined(USE_PAM) || defined(HAVE_CYGWIN) 947 static void 948 copy_environment_denylist(char **source, char ***env, u_int *envsize, 949 const char *denylist) 950 { 951 char *var_name, *var_val; 952 int i; 953 954 if (source == NULL) 955 return; 956 957 for(i = 0; source[i] != NULL; i++) { 958 var_name = xstrdup(source[i]); 959 if ((var_val = strstr(var_name, "=")) == NULL) { 960 free(var_name); 961 continue; 962 } 963 *var_val++ = '\0'; 964 965 if (denylist == NULL || 966 match_pattern_list(var_name, denylist, 0) != 1) { 967 debug3("Copy environment: %s=%s", var_name, var_val); 968 child_set_env(env, envsize, var_name, var_val); 969 } 970 971 free(var_name); 972 } 973 } 974 #endif /* defined(USE_PAM) || defined(HAVE_CYGWIN) */ 975 976 #ifdef HAVE_CYGWIN 977 static void 978 copy_environment(char **source, char ***env, u_int *envsize) 979 { 980 copy_environment_denylist(source, env, envsize, NULL); 981 } 982 #endif 983 984 static char ** 985 do_setup_env(struct ssh *ssh, Session *s, const char *shell) 986 { 987 char buf[256]; 988 size_t n; 989 u_int i, envsize; 990 char *ocp, *cp, *value, **env, *laddr; 991 struct passwd *pw = s->pw; 992 #if !defined (HAVE_LOGIN_CAP) && !defined (HAVE_CYGWIN) 993 char *path = NULL; 994 #else 995 extern char **environ; 996 char **senv, **var, *val; 997 #endif 998 999 /* Initialize the environment. */ 1000 envsize = 100; 1001 env = xcalloc(envsize, sizeof(char *)); 1002 env[0] = NULL; 1003 1004 #ifdef HAVE_CYGWIN 1005 /* 1006 * The Windows environment contains some setting which are 1007 * important for a running system. They must not be dropped. 1008 */ 1009 { 1010 char **p; 1011 1012 p = fetch_windows_environment(); 1013 copy_environment(p, &env, &envsize); 1014 free_windows_environment(p); 1015 } 1016 #endif 1017 1018 if (getenv("TZ")) 1019 child_set_env(&env, &envsize, "TZ", getenv("TZ")); 1020 1021 #ifdef GSSAPI 1022 /* Allow any GSSAPI methods that we've used to alter 1023 * the child's environment as they see fit 1024 */ 1025 ssh_gssapi_do_child(&env, &envsize); 1026 #endif 1027 1028 /* Set basic environment. */ 1029 for (i = 0; i < s->num_env; i++) 1030 child_set_env(&env, &envsize, s->env[i].name, s->env[i].val); 1031 1032 child_set_env(&env, &envsize, "USER", pw->pw_name); 1033 child_set_env(&env, &envsize, "LOGNAME", pw->pw_name); 1034 #ifdef _AIX 1035 child_set_env(&env, &envsize, "LOGIN", pw->pw_name); 1036 #endif 1037 child_set_env(&env, &envsize, "HOME", pw->pw_dir); 1038 snprintf(buf, sizeof buf, "%.200s/%.50s", _PATH_MAILDIR, pw->pw_name); 1039 child_set_env(&env, &envsize, "MAIL", buf); 1040 #ifdef HAVE_LOGIN_CAP 1041 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); 1042 child_set_env(&env, &envsize, "TERM", "su"); 1043 /* 1044 * Temporarily swap out our real environment with an empty one, 1045 * let setusercontext() apply any environment variables defined 1046 * for the user's login class, copy those variables to the child, 1047 * free the temporary environment, and restore the original. 1048 */ 1049 senv = environ; 1050 environ = xmalloc(sizeof(*environ)); 1051 *environ = NULL; 1052 (void)setusercontext(lc, pw, pw->pw_uid, LOGIN_SETENV|LOGIN_SETPATH); 1053 for (var = environ; *var != NULL; ++var) { 1054 if ((val = strchr(*var, '=')) != NULL) { 1055 *val++ = '\0'; 1056 child_set_env(&env, &envsize, *var, val); 1057 } 1058 free(*var); 1059 } 1060 free(environ); 1061 environ = senv; 1062 #else /* HAVE_LOGIN_CAP */ 1063 # ifndef HAVE_CYGWIN 1064 /* 1065 * There's no standard path on Windows. The path contains 1066 * important components pointing to the system directories, 1067 * needed for loading shared libraries. So the path better 1068 * remains intact here. 1069 */ 1070 # ifdef HAVE_ETC_DEFAULT_LOGIN 1071 read_etc_default_login(&env, &envsize, pw->pw_uid); 1072 path = child_get_env(env, "PATH"); 1073 # endif /* HAVE_ETC_DEFAULT_LOGIN */ 1074 if (path == NULL || *path == '\0') { 1075 child_set_env(&env, &envsize, "PATH", 1076 s->pw->pw_uid == 0 ? SUPERUSER_PATH : _PATH_STDPATH); 1077 } 1078 # endif /* HAVE_CYGWIN */ 1079 #endif /* HAVE_LOGIN_CAP */ 1080 1081 if (!options.use_pam) { 1082 snprintf(buf, sizeof buf, "%.200s/%.50s", 1083 _PATH_MAILDIR, pw->pw_name); 1084 child_set_env(&env, &envsize, "MAIL", buf); 1085 } 1086 1087 /* Normal systems set SHELL by default. */ 1088 child_set_env(&env, &envsize, "SHELL", shell); 1089 1090 if (s->term) 1091 child_set_env(&env, &envsize, "TERM", s->term); 1092 if (s->display) 1093 child_set_env(&env, &envsize, "DISPLAY", s->display); 1094 1095 /* 1096 * Since we clear KRB5CCNAME at startup, if it's set now then it 1097 * must have been set by a native authentication method (eg AIX or 1098 * SIA), so copy it to the child. 1099 */ 1100 { 1101 char *cp; 1102 1103 if ((cp = getenv("KRB5CCNAME")) != NULL) 1104 child_set_env(&env, &envsize, "KRB5CCNAME", cp); 1105 } 1106 1107 #ifdef _AIX 1108 { 1109 char *cp; 1110 1111 if ((cp = getenv("AUTHSTATE")) != NULL) 1112 child_set_env(&env, &envsize, "AUTHSTATE", cp); 1113 read_environment_file(&env, &envsize, "/etc/environment", 1114 options.permit_user_env_allowlist); 1115 } 1116 #endif 1117 #ifdef KRB5 1118 if (s->authctxt->krb5_ccname) 1119 child_set_env(&env, &envsize, "KRB5CCNAME", 1120 s->authctxt->krb5_ccname); 1121 #endif 1122 if (auth_sock_name != NULL) 1123 child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME, 1124 auth_sock_name); 1125 1126 1127 /* Set custom environment options from pubkey authentication. */ 1128 if (options.permit_user_env) { 1129 for (n = 0 ; n < auth_opts->nenv; n++) { 1130 ocp = xstrdup(auth_opts->env[n]); 1131 cp = strchr(ocp, '='); 1132 if (cp != NULL) { 1133 *cp = '\0'; 1134 /* Apply PermitUserEnvironment allowlist */ 1135 if (options.permit_user_env_allowlist == NULL || 1136 match_pattern_list(ocp, 1137 options.permit_user_env_allowlist, 0) == 1) 1138 child_set_env(&env, &envsize, 1139 ocp, cp + 1); 1140 } 1141 free(ocp); 1142 } 1143 } 1144 1145 /* read $HOME/.ssh/environment. */ 1146 if (options.permit_user_env) { 1147 snprintf(buf, sizeof buf, "%.200s/%s/environment", 1148 pw->pw_dir, _PATH_SSH_USER_DIR); 1149 read_environment_file(&env, &envsize, buf, 1150 options.permit_user_env_allowlist); 1151 } 1152 1153 #ifdef USE_PAM 1154 /* 1155 * Pull in any environment variables that may have 1156 * been set by PAM. 1157 */ 1158 if (options.use_pam) { 1159 char **p; 1160 1161 /* 1162 * Don't allow PAM-internal env vars to leak 1163 * back into the session environment. 1164 */ 1165 #define PAM_ENV_DENYLIST "SSH_AUTH_INFO*,SSH_CONNECTION*" 1166 p = fetch_pam_child_environment(); 1167 copy_environment_denylist(p, &env, &envsize, 1168 PAM_ENV_DENYLIST); 1169 free_pam_environment(p); 1170 1171 p = fetch_pam_environment(); 1172 copy_environment_denylist(p, &env, &envsize, 1173 PAM_ENV_DENYLIST); 1174 free_pam_environment(p); 1175 } 1176 #endif /* USE_PAM */ 1177 1178 /* Environment specified by admin */ 1179 for (i = 0; i < options.num_setenv; i++) { 1180 cp = xstrdup(options.setenv[i]); 1181 if ((value = strchr(cp, '=')) == NULL) { 1182 /* shouldn't happen; vars are checked in servconf.c */ 1183 fatal("Invalid config SetEnv: %s", options.setenv[i]); 1184 } 1185 *value++ = '\0'; 1186 child_set_env(&env, &envsize, cp, value); 1187 } 1188 1189 /* SSH_CLIENT deprecated */ 1190 snprintf(buf, sizeof buf, "%.50s %d %d", 1191 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 1192 ssh_local_port(ssh)); 1193 child_set_env(&env, &envsize, "SSH_CLIENT", buf); 1194 1195 laddr = get_local_ipaddr(ssh_packet_get_connection_in(ssh)); 1196 snprintf(buf, sizeof buf, "%.50s %d %.50s %d", 1197 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 1198 laddr, ssh_local_port(ssh)); 1199 free(laddr); 1200 child_set_env(&env, &envsize, "SSH_CONNECTION", buf); 1201 1202 if (tun_fwd_ifnames != NULL) 1203 child_set_env(&env, &envsize, "SSH_TUNNEL", tun_fwd_ifnames); 1204 if (auth_info_file != NULL) 1205 child_set_env(&env, &envsize, "SSH_USER_AUTH", auth_info_file); 1206 if (s->ttyfd != -1) 1207 child_set_env(&env, &envsize, "SSH_TTY", s->tty); 1208 if (original_command) 1209 child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND", 1210 original_command); 1211 1212 if (debug_flag) { 1213 /* dump the environment */ 1214 fprintf(stderr, "Environment:\n"); 1215 for (i = 0; env[i]; i++) 1216 fprintf(stderr, " %.200s\n", env[i]); 1217 } 1218 return env; 1219 } 1220 1221 /* 1222 * Run $HOME/.ssh/rc, /etc/ssh/sshrc, or xauth (whichever is found 1223 * first in this order). 1224 */ 1225 static void 1226 do_rc_files(struct ssh *ssh, Session *s, const char *shell) 1227 { 1228 FILE *f = NULL; 1229 char *cmd = NULL, *user_rc = NULL; 1230 int do_xauth; 1231 struct stat st; 1232 1233 do_xauth = 1234 s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL; 1235 xasprintf(&user_rc, "%s/%s", s->pw->pw_dir, _PATH_SSH_USER_RC); 1236 1237 /* ignore _PATH_SSH_USER_RC for subsystems and admin forced commands */ 1238 if (!s->is_subsystem && options.adm_forced_command == NULL && 1239 auth_opts->permit_user_rc && options.permit_user_rc && 1240 stat(user_rc, &st) >= 0) { 1241 if (xasprintf(&cmd, "%s -c '%s %s'", shell, _PATH_BSHELL, 1242 user_rc) == -1) 1243 fatal_f("xasprintf: %s", strerror(errno)); 1244 if (debug_flag) 1245 fprintf(stderr, "Running %s\n", cmd); 1246 f = popen(cmd, "w"); 1247 if (f) { 1248 if (do_xauth) 1249 fprintf(f, "%s %s\n", s->auth_proto, 1250 s->auth_data); 1251 pclose(f); 1252 } else 1253 fprintf(stderr, "Could not run %s\n", 1254 user_rc); 1255 } else if (stat(_PATH_SSH_SYSTEM_RC, &st) >= 0) { 1256 if (debug_flag) 1257 fprintf(stderr, "Running %s %s\n", _PATH_BSHELL, 1258 _PATH_SSH_SYSTEM_RC); 1259 f = popen(_PATH_BSHELL " " _PATH_SSH_SYSTEM_RC, "w"); 1260 if (f) { 1261 if (do_xauth) 1262 fprintf(f, "%s %s\n", s->auth_proto, 1263 s->auth_data); 1264 pclose(f); 1265 } else 1266 fprintf(stderr, "Could not run %s\n", 1267 _PATH_SSH_SYSTEM_RC); 1268 } else if (do_xauth && options.xauth_location != NULL) { 1269 /* Add authority data to .Xauthority if appropriate. */ 1270 if (debug_flag) { 1271 fprintf(stderr, 1272 "Running %.500s remove %.100s\n", 1273 options.xauth_location, s->auth_display); 1274 fprintf(stderr, 1275 "%.500s add %.100s %.100s %.100s\n", 1276 options.xauth_location, s->auth_display, 1277 s->auth_proto, s->auth_data); 1278 } 1279 if (xasprintf(&cmd, "%s -q -", options.xauth_location) == -1) 1280 fatal_f("xasprintf: %s", strerror(errno)); 1281 f = popen(cmd, "w"); 1282 if (f) { 1283 fprintf(f, "remove %s\n", 1284 s->auth_display); 1285 fprintf(f, "add %s %s %s\n", 1286 s->auth_display, s->auth_proto, 1287 s->auth_data); 1288 pclose(f); 1289 } else { 1290 fprintf(stderr, "Could not run %s\n", 1291 cmd); 1292 } 1293 } 1294 free(cmd); 1295 free(user_rc); 1296 } 1297 1298 static void 1299 do_nologin(struct passwd *pw) 1300 { 1301 FILE *f = NULL; 1302 const char *nl; 1303 char buf[1024], *def_nl = _PATH_NOLOGIN; 1304 struct stat sb; 1305 1306 #ifdef HAVE_LOGIN_CAP 1307 if (login_getcapbool(lc, "ignorenologin", 0) || pw->pw_uid == 0) 1308 return; 1309 nl = login_getcapstr(lc, "nologin", def_nl, def_nl); 1310 #else 1311 if (pw->pw_uid == 0) 1312 return; 1313 nl = def_nl; 1314 #endif 1315 if (stat(nl, &sb) == -1) 1316 return; 1317 1318 /* /etc/nologin exists. Print its contents if we can and exit. */ 1319 logit("User %.100s not allowed because %s exists", pw->pw_name, nl); 1320 if ((f = fopen(nl, "r")) != NULL) { 1321 while (fgets(buf, sizeof(buf), f)) 1322 fputs(buf, stderr); 1323 fclose(f); 1324 } 1325 exit(254); 1326 } 1327 1328 /* 1329 * Chroot into a directory after checking it for safety: all path components 1330 * must be root-owned directories with strict permissions. 1331 */ 1332 static void 1333 safely_chroot(const char *path, uid_t uid) 1334 { 1335 const char *cp; 1336 char component[PATH_MAX]; 1337 struct stat st; 1338 1339 if (!path_absolute(path)) 1340 fatal("chroot path does not begin at root"); 1341 if (strlen(path) >= sizeof(component)) 1342 fatal("chroot path too long"); 1343 1344 /* 1345 * Descend the path, checking that each component is a 1346 * root-owned directory with strict permissions. 1347 */ 1348 for (cp = path; cp != NULL;) { 1349 if ((cp = strchr(cp, '/')) == NULL) 1350 strlcpy(component, path, sizeof(component)); 1351 else { 1352 cp++; 1353 memcpy(component, path, cp - path); 1354 component[cp - path] = '\0'; 1355 } 1356 1357 debug3_f("checking '%s'", component); 1358 1359 if (stat(component, &st) != 0) 1360 fatal_f("stat(\"%s\"): %s", 1361 component, strerror(errno)); 1362 if (st.st_uid != 0 || (st.st_mode & 022) != 0) 1363 fatal("bad ownership or modes for chroot " 1364 "directory %s\"%s\"", 1365 cp == NULL ? "" : "component ", component); 1366 if (!S_ISDIR(st.st_mode)) 1367 fatal("chroot path %s\"%s\" is not a directory", 1368 cp == NULL ? "" : "component ", component); 1369 1370 } 1371 1372 if (chdir(path) == -1) 1373 fatal("Unable to chdir to chroot path \"%s\": " 1374 "%s", path, strerror(errno)); 1375 if (chroot(path) == -1) 1376 fatal("chroot(\"%s\"): %s", path, strerror(errno)); 1377 if (chdir("/") == -1) 1378 fatal_f("chdir(/) after chroot: %s", strerror(errno)); 1379 verbose("Changed root directory to \"%s\"", path); 1380 } 1381 1382 /* Set login name, uid, gid, and groups. */ 1383 void 1384 do_setusercontext(struct passwd *pw) 1385 { 1386 char uidstr[32], *chroot_path, *tmp; 1387 1388 platform_setusercontext(pw); 1389 1390 if (platform_privileged_uidswap()) { 1391 #ifdef HAVE_LOGIN_CAP 1392 if (setusercontext(lc, pw, pw->pw_uid, 1393 (LOGIN_SETALL & ~(LOGIN_SETENV|LOGIN_SETPATH|LOGIN_SETUSER))) < 0) { 1394 perror("unable to set user context"); 1395 exit(1); 1396 } 1397 #else 1398 if (setlogin(pw->pw_name) < 0) 1399 error("setlogin failed: %s", strerror(errno)); 1400 if (setgid(pw->pw_gid) < 0) { 1401 perror("setgid"); 1402 exit(1); 1403 } 1404 /* Initialize the group list. */ 1405 if (initgroups(pw->pw_name, pw->pw_gid) < 0) { 1406 perror("initgroups"); 1407 exit(1); 1408 } 1409 endgrent(); 1410 #endif 1411 1412 platform_setusercontext_post_groups(pw); 1413 1414 if (!in_chroot && options.chroot_directory != NULL && 1415 strcasecmp(options.chroot_directory, "none") != 0) { 1416 tmp = tilde_expand_filename(options.chroot_directory, 1417 pw->pw_uid); 1418 snprintf(uidstr, sizeof(uidstr), "%llu", 1419 (unsigned long long)pw->pw_uid); 1420 chroot_path = percent_expand(tmp, "h", pw->pw_dir, 1421 "u", pw->pw_name, "U", uidstr, (char *)NULL); 1422 safely_chroot(chroot_path, pw->pw_uid); 1423 free(tmp); 1424 free(chroot_path); 1425 /* Make sure we don't attempt to chroot again */ 1426 free(options.chroot_directory); 1427 options.chroot_directory = NULL; 1428 in_chroot = 1; 1429 } 1430 1431 #ifdef HAVE_LOGIN_CAP 1432 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUSER) < 0) { 1433 perror("unable to set user context (setuser)"); 1434 exit(1); 1435 } 1436 /* 1437 * FreeBSD's setusercontext() will not apply the user's 1438 * own umask setting unless running with the user's UID. 1439 */ 1440 (void) setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUMASK); 1441 #else 1442 # ifdef USE_LIBIAF 1443 /* 1444 * In a chroot environment, the set_id() will always fail; 1445 * typically because of the lack of necessary authentication 1446 * services and runtime such as ./usr/lib/libiaf.so, 1447 * ./usr/lib/libpam.so.1, and ./etc/passwd We skip it in the 1448 * internal sftp chroot case. We'll lose auditing and ACLs but 1449 * permanently_set_uid will take care of the rest. 1450 */ 1451 if (!in_chroot && set_id(pw->pw_name) != 0) 1452 fatal("set_id(%s) Failed", pw->pw_name); 1453 # endif /* USE_LIBIAF */ 1454 /* Permanently switch to the desired uid. */ 1455 permanently_set_uid(pw); 1456 #endif 1457 } else if (options.chroot_directory != NULL && 1458 strcasecmp(options.chroot_directory, "none") != 0) { 1459 fatal("server lacks privileges to chroot to ChrootDirectory"); 1460 } 1461 1462 if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) 1463 fatal("Failed to set uids to %u.", (u_int) pw->pw_uid); 1464 } 1465 1466 static void 1467 do_pwchange(Session *s) 1468 { 1469 fflush(NULL); 1470 fprintf(stderr, "WARNING: Your password has expired.\n"); 1471 if (s->ttyfd != -1) { 1472 fprintf(stderr, 1473 "You must change your password now and login again!\n"); 1474 #ifdef WITH_SELINUX 1475 setexeccon(NULL); 1476 #endif 1477 #ifdef PASSWD_NEEDS_USERNAME 1478 execl(_PATH_PASSWD_PROG, "passwd", s->pw->pw_name, 1479 (char *)NULL); 1480 #else 1481 execl(_PATH_PASSWD_PROG, "passwd", (char *)NULL); 1482 #endif 1483 perror("passwd"); 1484 } else { 1485 fprintf(stderr, 1486 "Password change required but no TTY available.\n"); 1487 } 1488 exit(1); 1489 } 1490 1491 static void 1492 child_close_fds(struct ssh *ssh) 1493 { 1494 extern int auth_sock; 1495 1496 if (auth_sock != -1) { 1497 close(auth_sock); 1498 auth_sock = -1; 1499 } 1500 1501 if (ssh_packet_get_connection_in(ssh) == 1502 ssh_packet_get_connection_out(ssh)) 1503 close(ssh_packet_get_connection_in(ssh)); 1504 else { 1505 close(ssh_packet_get_connection_in(ssh)); 1506 close(ssh_packet_get_connection_out(ssh)); 1507 } 1508 /* 1509 * Close all descriptors related to channels. They will still remain 1510 * open in the parent. 1511 */ 1512 /* XXX better use close-on-exec? -markus */ 1513 channel_close_all(ssh); 1514 1515 /* 1516 * Close any extra file descriptors. Note that there may still be 1517 * descriptors left by system functions. They will be closed later. 1518 */ 1519 endpwent(); 1520 1521 /* Stop directing logs to a high-numbered fd before we close it */ 1522 log_redirect_stderr_to(NULL); 1523 1524 /* 1525 * Close any extra open file descriptors so that we don't have them 1526 * hanging around in clients. Note that we want to do this after 1527 * initgroups, because at least on Solaris 2.3 it leaves file 1528 * descriptors open. 1529 */ 1530 closefrom(STDERR_FILENO + 1); 1531 } 1532 1533 /* 1534 * Performs common processing for the child, such as setting up the 1535 * environment, closing extra file descriptors, setting the user and group 1536 * ids, and executing the command or shell. 1537 */ 1538 #define ARGV_MAX 10 1539 void 1540 do_child(struct ssh *ssh, Session *s, const char *command) 1541 { 1542 extern char **environ; 1543 char **env, *argv[ARGV_MAX], remote_id[512]; 1544 const char *shell, *shell0; 1545 struct passwd *pw = s->pw; 1546 int r = 0; 1547 1548 sshpkt_fmt_connection_id(ssh, remote_id, sizeof(remote_id)); 1549 1550 /* remove hostkey from the child's memory */ 1551 destroy_sensitive_data(); 1552 ssh_packet_clear_keys(ssh); 1553 1554 /* Force a password change */ 1555 if (s->authctxt->force_pwchange) { 1556 do_setusercontext(pw); 1557 child_close_fds(ssh); 1558 do_pwchange(s); 1559 exit(1); 1560 } 1561 1562 /* 1563 * Login(1) does this as well, and it needs uid 0 for the "-h" 1564 * switch, so we let login(1) to this for us. 1565 */ 1566 #ifdef HAVE_OSF_SIA 1567 session_setup_sia(pw, s->ttyfd == -1 ? NULL : s->tty); 1568 if (!check_quietlogin(s, command)) 1569 do_motd(); 1570 #else /* HAVE_OSF_SIA */ 1571 /* When PAM is enabled we rely on it to do the nologin check */ 1572 if (!options.use_pam) 1573 do_nologin(pw); 1574 do_setusercontext(pw); 1575 /* 1576 * PAM session modules in do_setusercontext may have 1577 * generated messages, so if this in an interactive 1578 * login then display them too. 1579 */ 1580 if (!check_quietlogin(s, command)) 1581 display_loginmsg(); 1582 #endif /* HAVE_OSF_SIA */ 1583 1584 #ifdef USE_PAM 1585 if (options.use_pam && !is_pam_session_open()) { 1586 debug3("PAM session not opened, exiting"); 1587 display_loginmsg(); 1588 exit(254); 1589 } 1590 #endif 1591 1592 /* 1593 * Get the shell from the password data. An empty shell field is 1594 * legal, and means /bin/sh. 1595 */ 1596 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; 1597 1598 /* 1599 * Make sure $SHELL points to the shell from the password file, 1600 * even if shell is overridden from login.conf 1601 */ 1602 env = do_setup_env(ssh, s, shell); 1603 1604 #ifdef HAVE_LOGIN_CAP 1605 shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell); 1606 #endif 1607 1608 /* 1609 * Close the connection descriptors; note that this is the child, and 1610 * the server will still have the socket open, and it is important 1611 * that we do not shutdown it. Note that the descriptors cannot be 1612 * closed before building the environment, as we call 1613 * ssh_remote_ipaddr there. 1614 */ 1615 child_close_fds(ssh); 1616 1617 /* 1618 * Must take new environment into use so that .ssh/rc, 1619 * /etc/ssh/sshrc and xauth are run in the proper environment. 1620 */ 1621 environ = env; 1622 1623 #if defined(KRB5) && defined(USE_AFS) 1624 /* 1625 * At this point, we check to see if AFS is active and if we have 1626 * a valid Kerberos 5 TGT. If so, it seems like a good idea to see 1627 * if we can (and need to) extend the ticket into an AFS token. If 1628 * we don't do this, we run into potential problems if the user's 1629 * home directory is in AFS and it's not world-readable. 1630 */ 1631 1632 if (options.kerberos_get_afs_token && k_hasafs() && 1633 (s->authctxt->krb5_ctx != NULL)) { 1634 char cell[64]; 1635 1636 debug("Getting AFS token"); 1637 1638 k_setpag(); 1639 1640 if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0) 1641 krb5_afslog(s->authctxt->krb5_ctx, 1642 s->authctxt->krb5_fwd_ccache, cell, NULL); 1643 1644 krb5_afslog_home(s->authctxt->krb5_ctx, 1645 s->authctxt->krb5_fwd_ccache, NULL, NULL, pw->pw_dir); 1646 } 1647 #endif 1648 1649 /* Change current directory to the user's home directory. */ 1650 if (chdir(pw->pw_dir) == -1) { 1651 /* Suppress missing homedir warning for chroot case */ 1652 #ifdef HAVE_LOGIN_CAP 1653 r = login_getcapbool(lc, "requirehome", 0); 1654 #endif 1655 if (r || !in_chroot) { 1656 fprintf(stderr, "Could not chdir to home " 1657 "directory %s: %s\n", pw->pw_dir, 1658 strerror(errno)); 1659 } 1660 if (r) 1661 exit(1); 1662 } 1663 1664 closefrom(STDERR_FILENO + 1); 1665 1666 do_rc_files(ssh, s, shell); 1667 1668 /* restore SIGPIPE for child */ 1669 ssh_signal(SIGPIPE, SIG_DFL); 1670 1671 if (s->is_subsystem == SUBSYSTEM_INT_SFTP_ERROR) { 1672 error("Connection from %s: refusing non-sftp session", 1673 remote_id); 1674 printf("This service allows sftp connections only.\n"); 1675 fflush(NULL); 1676 exit(1); 1677 } else if (s->is_subsystem == SUBSYSTEM_INT_SFTP) { 1678 extern int optind, optreset; 1679 int i; 1680 char *p, *args; 1681 1682 setproctitle("%s@%s", s->pw->pw_name, INTERNAL_SFTP_NAME); 1683 args = xstrdup(command ? command : "sftp-server"); 1684 for (i = 0, (p = strtok(args, " ")); p; (p = strtok(NULL, " "))) 1685 if (i < ARGV_MAX - 1) 1686 argv[i++] = p; 1687 argv[i] = NULL; 1688 optind = optreset = 1; 1689 __progname = argv[0]; 1690 #ifdef WITH_SELINUX 1691 ssh_selinux_change_context("sftpd_t"); 1692 #endif 1693 exit(sftp_server_main(i, argv, s->pw)); 1694 } 1695 1696 fflush(NULL); 1697 1698 /* Get the last component of the shell name. */ 1699 if ((shell0 = strrchr(shell, '/')) != NULL) 1700 shell0++; 1701 else 1702 shell0 = shell; 1703 1704 /* 1705 * If we have no command, execute the shell. In this case, the shell 1706 * name to be passed in argv[0] is preceded by '-' to indicate that 1707 * this is a login shell. 1708 */ 1709 if (!command) { 1710 char argv0[256]; 1711 1712 /* Start the shell. Set initial character to '-'. */ 1713 argv0[0] = '-'; 1714 1715 if (strlcpy(argv0 + 1, shell0, sizeof(argv0) - 1) 1716 >= sizeof(argv0) - 1) { 1717 errno = EINVAL; 1718 perror(shell); 1719 exit(1); 1720 } 1721 1722 /* Execute the shell. */ 1723 argv[0] = argv0; 1724 argv[1] = NULL; 1725 execve(shell, argv, env); 1726 1727 /* Executing the shell failed. */ 1728 perror(shell); 1729 exit(1); 1730 } 1731 /* 1732 * Execute the command using the user's shell. This uses the -c 1733 * option to execute the command. 1734 */ 1735 argv[0] = (char *) shell0; 1736 argv[1] = "-c"; 1737 argv[2] = (char *) command; 1738 argv[3] = NULL; 1739 execve(shell, argv, env); 1740 perror(shell); 1741 exit(1); 1742 } 1743 1744 void 1745 session_unused(int id) 1746 { 1747 debug3_f("session id %d unused", id); 1748 if (id >= options.max_sessions || 1749 id >= sessions_nalloc) { 1750 fatal_f("insane session id %d (max %d nalloc %d)", 1751 id, options.max_sessions, sessions_nalloc); 1752 } 1753 memset(&sessions[id], 0, sizeof(*sessions)); 1754 sessions[id].self = id; 1755 sessions[id].used = 0; 1756 sessions[id].chanid = -1; 1757 sessions[id].ptyfd = -1; 1758 sessions[id].ttyfd = -1; 1759 sessions[id].ptymaster = -1; 1760 sessions[id].x11_chanids = NULL; 1761 sessions[id].next_unused = sessions_first_unused; 1762 sessions_first_unused = id; 1763 } 1764 1765 Session * 1766 session_new(void) 1767 { 1768 Session *s, *tmp; 1769 1770 if (sessions_first_unused == -1) { 1771 if (sessions_nalloc >= options.max_sessions) 1772 return NULL; 1773 debug2_f("allocate (allocated %d max %d)", 1774 sessions_nalloc, options.max_sessions); 1775 tmp = xrecallocarray(sessions, sessions_nalloc, 1776 sessions_nalloc + 1, sizeof(*sessions)); 1777 if (tmp == NULL) { 1778 error_f("cannot allocate %d sessions", 1779 sessions_nalloc + 1); 1780 return NULL; 1781 } 1782 sessions = tmp; 1783 session_unused(sessions_nalloc++); 1784 } 1785 1786 if (sessions_first_unused >= sessions_nalloc || 1787 sessions_first_unused < 0) { 1788 fatal_f("insane first_unused %d max %d nalloc %d", 1789 sessions_first_unused, options.max_sessions, 1790 sessions_nalloc); 1791 } 1792 1793 s = &sessions[sessions_first_unused]; 1794 if (s->used) 1795 fatal_f("session %d already used", sessions_first_unused); 1796 sessions_first_unused = s->next_unused; 1797 s->used = 1; 1798 s->next_unused = -1; 1799 debug("session_new: session %d", s->self); 1800 1801 return s; 1802 } 1803 1804 static void 1805 session_dump(void) 1806 { 1807 int i; 1808 for (i = 0; i < sessions_nalloc; i++) { 1809 Session *s = &sessions[i]; 1810 1811 debug("dump: used %d next_unused %d session %d " 1812 "channel %d pid %ld", 1813 s->used, 1814 s->next_unused, 1815 s->self, 1816 s->chanid, 1817 (long)s->pid); 1818 } 1819 } 1820 1821 int 1822 session_open(Authctxt *authctxt, int chanid) 1823 { 1824 Session *s = session_new(); 1825 debug("session_open: channel %d", chanid); 1826 if (s == NULL) { 1827 error("no more sessions"); 1828 return 0; 1829 } 1830 s->authctxt = authctxt; 1831 s->pw = authctxt->pw; 1832 if (s->pw == NULL || !authctxt->valid) 1833 fatal("no user for session %d", s->self); 1834 debug("session_open: session %d: link with channel %d", s->self, chanid); 1835 s->chanid = chanid; 1836 return 1; 1837 } 1838 1839 Session * 1840 session_by_tty(char *tty) 1841 { 1842 int i; 1843 for (i = 0; i < sessions_nalloc; i++) { 1844 Session *s = &sessions[i]; 1845 if (s->used && s->ttyfd != -1 && strcmp(s->tty, tty) == 0) { 1846 debug("session_by_tty: session %d tty %s", i, tty); 1847 return s; 1848 } 1849 } 1850 debug("session_by_tty: unknown tty %.100s", tty); 1851 session_dump(); 1852 return NULL; 1853 } 1854 1855 static Session * 1856 session_by_channel(int id) 1857 { 1858 int i; 1859 for (i = 0; i < sessions_nalloc; i++) { 1860 Session *s = &sessions[i]; 1861 if (s->used && s->chanid == id) { 1862 debug("session_by_channel: session %d channel %d", 1863 i, id); 1864 return s; 1865 } 1866 } 1867 debug("session_by_channel: unknown channel %d", id); 1868 session_dump(); 1869 return NULL; 1870 } 1871 1872 static Session * 1873 session_by_x11_channel(int id) 1874 { 1875 int i, j; 1876 1877 for (i = 0; i < sessions_nalloc; i++) { 1878 Session *s = &sessions[i]; 1879 1880 if (s->x11_chanids == NULL || !s->used) 1881 continue; 1882 for (j = 0; s->x11_chanids[j] != -1; j++) { 1883 if (s->x11_chanids[j] == id) { 1884 debug("session_by_x11_channel: session %d " 1885 "channel %d", s->self, id); 1886 return s; 1887 } 1888 } 1889 } 1890 debug("session_by_x11_channel: unknown channel %d", id); 1891 session_dump(); 1892 return NULL; 1893 } 1894 1895 static Session * 1896 session_by_pid(pid_t pid) 1897 { 1898 int i; 1899 debug("session_by_pid: pid %ld", (long)pid); 1900 for (i = 0; i < sessions_nalloc; i++) { 1901 Session *s = &sessions[i]; 1902 if (s->used && s->pid == pid) 1903 return s; 1904 } 1905 error("session_by_pid: unknown pid %ld", (long)pid); 1906 session_dump(); 1907 return NULL; 1908 } 1909 1910 static int 1911 session_window_change_req(struct ssh *ssh, Session *s) 1912 { 1913 int r; 1914 1915 if ((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 (r = sshpkt_get_end(ssh)) != 0) 1920 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 1921 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 1922 return 1; 1923 } 1924 1925 static int 1926 session_pty_req(struct ssh *ssh, Session *s) 1927 { 1928 int r; 1929 1930 if (!auth_opts->permit_pty_flag || !options.permit_tty) { 1931 debug("Allocating a pty not permitted for this connection."); 1932 return 0; 1933 } 1934 if (s->ttyfd != -1) { 1935 ssh_packet_disconnect(ssh, "Protocol error: you already have a pty."); 1936 return 0; 1937 } 1938 1939 if ((r = sshpkt_get_cstring(ssh, &s->term, NULL)) != 0 || 1940 (r = sshpkt_get_u32(ssh, &s->col)) != 0 || 1941 (r = sshpkt_get_u32(ssh, &s->row)) != 0 || 1942 (r = sshpkt_get_u32(ssh, &s->xpixel)) != 0 || 1943 (r = sshpkt_get_u32(ssh, &s->ypixel)) != 0) 1944 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 1945 1946 if (strcmp(s->term, "") == 0) { 1947 free(s->term); 1948 s->term = NULL; 1949 } 1950 1951 /* Allocate a pty and open it. */ 1952 debug("Allocating pty."); 1953 if (!PRIVSEP(pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, 1954 sizeof(s->tty)))) { 1955 free(s->term); 1956 s->term = NULL; 1957 s->ptyfd = -1; 1958 s->ttyfd = -1; 1959 error("session_pty_req: session %d alloc failed", s->self); 1960 return 0; 1961 } 1962 debug("session_pty_req: session %d alloc %s", s->self, s->tty); 1963 1964 ssh_tty_parse_modes(ssh, s->ttyfd); 1965 1966 if ((r = sshpkt_get_end(ssh)) != 0) 1967 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 1968 1969 if (!use_privsep) 1970 pty_setowner(s->pw, s->tty); 1971 1972 /* Set window size from the packet. */ 1973 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 1974 1975 session_proctitle(s); 1976 return 1; 1977 } 1978 1979 static int 1980 session_subsystem_req(struct ssh *ssh, Session *s) 1981 { 1982 struct stat st; 1983 int r, success = 0; 1984 char *prog, *cmd; 1985 u_int i; 1986 1987 if ((r = sshpkt_get_cstring(ssh, &s->subsys, NULL)) != 0 || 1988 (r = sshpkt_get_end(ssh)) != 0) 1989 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 1990 debug2("subsystem request for %.100s by user %s", s->subsys, 1991 s->pw->pw_name); 1992 1993 for (i = 0; i < options.num_subsystems; i++) { 1994 if (strcmp(s->subsys, options.subsystem_name[i]) == 0) { 1995 prog = options.subsystem_command[i]; 1996 cmd = options.subsystem_args[i]; 1997 if (strcmp(INTERNAL_SFTP_NAME, prog) == 0) { 1998 s->is_subsystem = SUBSYSTEM_INT_SFTP; 1999 debug("subsystem: %s", prog); 2000 } else { 2001 if (stat(prog, &st) == -1) 2002 debug("subsystem: cannot stat %s: %s", 2003 prog, strerror(errno)); 2004 s->is_subsystem = SUBSYSTEM_EXT; 2005 debug("subsystem: exec() %s", cmd); 2006 } 2007 success = do_exec(ssh, s, cmd) == 0; 2008 break; 2009 } 2010 } 2011 2012 if (!success) 2013 logit("subsystem request for %.100s by user %s failed, " 2014 "subsystem not found", s->subsys, s->pw->pw_name); 2015 2016 return success; 2017 } 2018 2019 static int 2020 session_x11_req(struct ssh *ssh, Session *s) 2021 { 2022 int r, success; 2023 u_char single_connection = 0; 2024 2025 if (s->auth_proto != NULL || s->auth_data != NULL) { 2026 error("session_x11_req: session %d: " 2027 "x11 forwarding already active", s->self); 2028 return 0; 2029 } 2030 if ((r = sshpkt_get_u8(ssh, &single_connection)) != 0 || 2031 (r = sshpkt_get_cstring(ssh, &s->auth_proto, NULL)) != 0 || 2032 (r = sshpkt_get_cstring(ssh, &s->auth_data, NULL)) != 0 || 2033 (r = sshpkt_get_u32(ssh, &s->screen)) != 0 || 2034 (r = sshpkt_get_end(ssh)) != 0) 2035 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 2036 2037 s->single_connection = single_connection; 2038 2039 if (xauth_valid_string(s->auth_proto) && 2040 xauth_valid_string(s->auth_data)) 2041 success = session_setup_x11fwd(ssh, s); 2042 else { 2043 success = 0; 2044 error("Invalid X11 forwarding data"); 2045 } 2046 if (!success) { 2047 free(s->auth_proto); 2048 free(s->auth_data); 2049 s->auth_proto = NULL; 2050 s->auth_data = NULL; 2051 } 2052 return success; 2053 } 2054 2055 static int 2056 session_shell_req(struct ssh *ssh, Session *s) 2057 { 2058 int r; 2059 2060 if ((r = sshpkt_get_end(ssh)) != 0) 2061 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 2062 return do_exec(ssh, s, NULL) == 0; 2063 } 2064 2065 static int 2066 session_exec_req(struct ssh *ssh, Session *s) 2067 { 2068 u_int success; 2069 int r; 2070 char *command = NULL; 2071 2072 if ((r = sshpkt_get_cstring(ssh, &command, NULL)) != 0 || 2073 (r = sshpkt_get_end(ssh)) != 0) 2074 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 2075 2076 success = do_exec(ssh, s, command) == 0; 2077 free(command); 2078 return success; 2079 } 2080 2081 static int 2082 session_break_req(struct ssh *ssh, Session *s) 2083 { 2084 int r; 2085 2086 if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* ignore */ 2087 (r = sshpkt_get_end(ssh)) != 0) 2088 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 2089 2090 if (s->ptymaster == -1 || tcsendbreak(s->ptymaster, 0) == -1) 2091 return 0; 2092 return 1; 2093 } 2094 2095 static int 2096 session_env_req(struct ssh *ssh, Session *s) 2097 { 2098 char *name, *val; 2099 u_int i; 2100 int r; 2101 2102 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 || 2103 (r = sshpkt_get_cstring(ssh, &val, NULL)) != 0 || 2104 (r = sshpkt_get_end(ssh)) != 0) 2105 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 2106 2107 /* Don't set too many environment variables */ 2108 if (s->num_env > 128) { 2109 debug2("Ignoring env request %s: too many env vars", name); 2110 goto fail; 2111 } 2112 2113 for (i = 0; i < options.num_accept_env; i++) { 2114 if (match_pattern(name, options.accept_env[i])) { 2115 debug2("Setting env %d: %s=%s", s->num_env, name, val); 2116 s->env = xrecallocarray(s->env, s->num_env, 2117 s->num_env + 1, sizeof(*s->env)); 2118 s->env[s->num_env].name = name; 2119 s->env[s->num_env].val = val; 2120 s->num_env++; 2121 return (1); 2122 } 2123 } 2124 debug2("Ignoring env request %s: disallowed name", name); 2125 2126 fail: 2127 free(name); 2128 free(val); 2129 return (0); 2130 } 2131 2132 /* 2133 * Conversion of signals from ssh channel request names. 2134 * Subset of signals from RFC 4254 section 6.10C, with SIGINFO as 2135 * local extension. 2136 */ 2137 static int 2138 name2sig(char *name) 2139 { 2140 #define SSH_SIG(x) if (strcmp(name, #x) == 0) return SIG ## x 2141 SSH_SIG(HUP); 2142 SSH_SIG(INT); 2143 SSH_SIG(KILL); 2144 SSH_SIG(QUIT); 2145 SSH_SIG(TERM); 2146 SSH_SIG(USR1); 2147 SSH_SIG(USR2); 2148 #undef SSH_SIG 2149 #ifdef SIGINFO 2150 if (strcmp(name, "INFO@openssh.com") == 0) 2151 return SIGINFO; 2152 #endif 2153 return -1; 2154 } 2155 2156 static int 2157 session_signal_req(struct ssh *ssh, Session *s) 2158 { 2159 char *signame = NULL; 2160 int r, sig, success = 0; 2161 2162 if ((r = sshpkt_get_cstring(ssh, &signame, NULL)) != 0 || 2163 (r = sshpkt_get_end(ssh)) != 0) { 2164 error_fr(r, "parse"); 2165 goto out; 2166 } 2167 if ((sig = name2sig(signame)) == -1) { 2168 error_f("unsupported signal \"%s\"", signame); 2169 goto out; 2170 } 2171 if (s->pid <= 0) { 2172 error_f("no pid for session %d", s->self); 2173 goto out; 2174 } 2175 if (s->forced || s->is_subsystem) { 2176 error_f("refusing to send signal %s to %s session", 2177 signame, s->forced ? "forced-command" : "subsystem"); 2178 goto out; 2179 } 2180 if (!use_privsep || mm_is_monitor()) { 2181 error_f("session signalling requires privilege separation"); 2182 goto out; 2183 } 2184 2185 debug_f("signal %s, killpg(%ld, %d)", signame, (long)s->pid, sig); 2186 temporarily_use_uid(s->pw); 2187 r = killpg(s->pid, sig); 2188 restore_uid(); 2189 if (r != 0) { 2190 error_f("killpg(%ld, %d): %s", (long)s->pid, 2191 sig, strerror(errno)); 2192 goto out; 2193 } 2194 2195 /* success */ 2196 success = 1; 2197 out: 2198 free(signame); 2199 return success; 2200 } 2201 2202 static int 2203 session_auth_agent_req(struct ssh *ssh, Session *s) 2204 { 2205 static int called = 0; 2206 int r; 2207 2208 if ((r = sshpkt_get_end(ssh)) != 0) 2209 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 2210 if (!auth_opts->permit_agent_forwarding_flag || 2211 !options.allow_agent_forwarding) { 2212 debug_f("agent forwarding disabled"); 2213 return 0; 2214 } 2215 if (called) { 2216 return 0; 2217 } else { 2218 called = 1; 2219 return auth_input_request_forwarding(ssh, s->pw); 2220 } 2221 } 2222 2223 int 2224 session_input_channel_req(struct ssh *ssh, Channel *c, const char *rtype) 2225 { 2226 int success = 0; 2227 Session *s; 2228 2229 if ((s = session_by_channel(c->self)) == NULL) { 2230 logit_f("no session %d req %.100s", c->self, rtype); 2231 return 0; 2232 } 2233 debug_f("session %d req %s", s->self, rtype); 2234 2235 /* 2236 * a session is in LARVAL state until a shell, a command 2237 * or a subsystem is executed 2238 */ 2239 if (c->type == SSH_CHANNEL_LARVAL) { 2240 if (strcmp(rtype, "shell") == 0) { 2241 success = session_shell_req(ssh, s); 2242 } else if (strcmp(rtype, "exec") == 0) { 2243 success = session_exec_req(ssh, s); 2244 } else if (strcmp(rtype, "pty-req") == 0) { 2245 success = session_pty_req(ssh, s); 2246 } else if (strcmp(rtype, "x11-req") == 0) { 2247 success = session_x11_req(ssh, s); 2248 } else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) { 2249 success = session_auth_agent_req(ssh, s); 2250 } else if (strcmp(rtype, "subsystem") == 0) { 2251 success = session_subsystem_req(ssh, s); 2252 } else if (strcmp(rtype, "env") == 0) { 2253 success = session_env_req(ssh, s); 2254 } 2255 } 2256 if (strcmp(rtype, "window-change") == 0) { 2257 success = session_window_change_req(ssh, s); 2258 } else if (strcmp(rtype, "break") == 0) { 2259 success = session_break_req(ssh, s); 2260 } else if (strcmp(rtype, "signal") == 0) { 2261 success = session_signal_req(ssh, s); 2262 } 2263 2264 return success; 2265 } 2266 2267 void 2268 session_set_fds(struct ssh *ssh, Session *s, 2269 int fdin, int fdout, int fderr, int ignore_fderr, int is_tty) 2270 { 2271 /* 2272 * now that have a child and a pipe to the child, 2273 * we can activate our channel and register the fd's 2274 */ 2275 if (s->chanid == -1) 2276 fatal("no channel for session %d", s->self); 2277 channel_set_fds(ssh, s->chanid, 2278 fdout, fdin, fderr, 2279 ignore_fderr ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ, 2280 1, is_tty, CHAN_SES_WINDOW_DEFAULT); 2281 } 2282 2283 /* 2284 * Function to perform pty cleanup. Also called if we get aborted abnormally 2285 * (e.g., due to a dropped connection). 2286 */ 2287 void 2288 session_pty_cleanup2(Session *s) 2289 { 2290 if (s == NULL) { 2291 error_f("no session"); 2292 return; 2293 } 2294 if (s->ttyfd == -1) 2295 return; 2296 2297 debug_f("session %d release %s", s->self, s->tty); 2298 2299 /* Record that the user has logged out. */ 2300 if (s->pid != 0) 2301 record_logout(s->pid, s->tty, s->pw->pw_name); 2302 2303 /* Release the pseudo-tty. */ 2304 if (getuid() == 0) 2305 pty_release(s->tty); 2306 2307 /* 2308 * Close the server side of the socket pairs. We must do this after 2309 * the pty cleanup, so that another process doesn't get this pty 2310 * while we're still cleaning up. 2311 */ 2312 if (s->ptymaster != -1 && close(s->ptymaster) == -1) 2313 error("close(s->ptymaster/%d): %s", 2314 s->ptymaster, strerror(errno)); 2315 2316 /* unlink pty from session */ 2317 s->ttyfd = -1; 2318 } 2319 2320 void 2321 session_pty_cleanup(Session *s) 2322 { 2323 PRIVSEP(session_pty_cleanup2(s)); 2324 } 2325 2326 static char * 2327 sig2name(int sig) 2328 { 2329 #define SSH_SIG(x) if (sig == SIG ## x) return #x 2330 SSH_SIG(ABRT); 2331 SSH_SIG(ALRM); 2332 SSH_SIG(FPE); 2333 SSH_SIG(HUP); 2334 SSH_SIG(ILL); 2335 SSH_SIG(INT); 2336 SSH_SIG(KILL); 2337 SSH_SIG(PIPE); 2338 SSH_SIG(QUIT); 2339 SSH_SIG(SEGV); 2340 SSH_SIG(TERM); 2341 SSH_SIG(USR1); 2342 SSH_SIG(USR2); 2343 #undef SSH_SIG 2344 return "SIG@openssh.com"; 2345 } 2346 2347 static void 2348 session_close_x11(struct ssh *ssh, int id) 2349 { 2350 Channel *c; 2351 2352 if ((c = channel_by_id(ssh, id)) == NULL) { 2353 debug_f("x11 channel %d missing", id); 2354 } else { 2355 /* Detach X11 listener */ 2356 debug_f("detach x11 channel %d", id); 2357 channel_cancel_cleanup(ssh, id); 2358 if (c->ostate != CHAN_OUTPUT_CLOSED) 2359 chan_mark_dead(ssh, c); 2360 } 2361 } 2362 2363 static void 2364 session_close_single_x11(struct ssh *ssh, int id, void *arg) 2365 { 2366 Session *s; 2367 u_int i; 2368 2369 debug3_f("channel %d", id); 2370 channel_cancel_cleanup(ssh, id); 2371 if ((s = session_by_x11_channel(id)) == NULL) 2372 fatal_f("no x11 channel %d", id); 2373 for (i = 0; s->x11_chanids[i] != -1; i++) { 2374 debug_f("session %d: closing channel %d", 2375 s->self, s->x11_chanids[i]); 2376 /* 2377 * The channel "id" is already closing, but make sure we 2378 * close all of its siblings. 2379 */ 2380 if (s->x11_chanids[i] != id) 2381 session_close_x11(ssh, s->x11_chanids[i]); 2382 } 2383 free(s->x11_chanids); 2384 s->x11_chanids = NULL; 2385 free(s->display); 2386 s->display = NULL; 2387 free(s->auth_proto); 2388 s->auth_proto = NULL; 2389 free(s->auth_data); 2390 s->auth_data = NULL; 2391 free(s->auth_display); 2392 s->auth_display = NULL; 2393 } 2394 2395 static void 2396 session_exit_message(struct ssh *ssh, Session *s, int status) 2397 { 2398 Channel *c; 2399 int r; 2400 2401 if ((c = channel_lookup(ssh, s->chanid)) == NULL) 2402 fatal_f("session %d: no channel %d", s->self, s->chanid); 2403 debug_f("session %d channel %d pid %ld", 2404 s->self, s->chanid, (long)s->pid); 2405 2406 if (WIFEXITED(status)) { 2407 channel_request_start(ssh, s->chanid, "exit-status", 0); 2408 if ((r = sshpkt_put_u32(ssh, WEXITSTATUS(status))) != 0 || 2409 (r = sshpkt_send(ssh)) != 0) 2410 sshpkt_fatal(ssh, r, "%s: exit reply", __func__); 2411 } else if (WIFSIGNALED(status)) { 2412 channel_request_start(ssh, s->chanid, "exit-signal", 0); 2413 #ifndef WCOREDUMP 2414 # define WCOREDUMP(x) (0) 2415 #endif 2416 if ((r = sshpkt_put_cstring(ssh, sig2name(WTERMSIG(status)))) != 0 || 2417 (r = sshpkt_put_u8(ssh, WCOREDUMP(status)? 1 : 0)) != 0 || 2418 (r = sshpkt_put_cstring(ssh, "")) != 0 || 2419 (r = sshpkt_put_cstring(ssh, "")) != 0 || 2420 (r = sshpkt_send(ssh)) != 0) 2421 sshpkt_fatal(ssh, r, "%s: exit reply", __func__); 2422 } else { 2423 /* Some weird exit cause. Just exit. */ 2424 ssh_packet_disconnect(ssh, "wait returned status %04x.", status); 2425 } 2426 2427 /* disconnect channel */ 2428 debug_f("release channel %d", s->chanid); 2429 2430 /* 2431 * Adjust cleanup callback attachment to send close messages when 2432 * the channel gets EOF. The session will be then be closed 2433 * by session_close_by_channel when the child sessions close their fds. 2434 */ 2435 channel_register_cleanup(ssh, c->self, session_close_by_channel, 1); 2436 2437 /* 2438 * emulate a write failure with 'chan_write_failed', nobody will be 2439 * interested in data we write. 2440 * Note that we must not call 'chan_read_failed', since there could 2441 * be some more data waiting in the pipe. 2442 */ 2443 if (c->ostate != CHAN_OUTPUT_CLOSED) 2444 chan_write_failed(ssh, c); 2445 } 2446 2447 void 2448 session_close(struct ssh *ssh, Session *s) 2449 { 2450 u_int i; 2451 2452 verbose("Close session: user %s from %.200s port %d id %d", 2453 s->pw->pw_name, 2454 ssh_remote_ipaddr(ssh), 2455 ssh_remote_port(ssh), 2456 s->self); 2457 2458 if (s->ttyfd != -1) 2459 session_pty_cleanup(s); 2460 free(s->term); 2461 free(s->display); 2462 free(s->x11_chanids); 2463 free(s->auth_display); 2464 free(s->auth_data); 2465 free(s->auth_proto); 2466 free(s->subsys); 2467 if (s->env != NULL) { 2468 for (i = 0; i < s->num_env; i++) { 2469 free(s->env[i].name); 2470 free(s->env[i].val); 2471 } 2472 free(s->env); 2473 } 2474 session_proctitle(s); 2475 session_unused(s->self); 2476 } 2477 2478 void 2479 session_close_by_pid(struct ssh *ssh, pid_t pid, int status) 2480 { 2481 Session *s = session_by_pid(pid); 2482 if (s == NULL) { 2483 debug_f("no session for pid %ld", (long)pid); 2484 return; 2485 } 2486 if (s->chanid != -1) 2487 session_exit_message(ssh, s, status); 2488 if (s->ttyfd != -1) 2489 session_pty_cleanup(s); 2490 s->pid = 0; 2491 } 2492 2493 /* 2494 * this is called when a channel dies before 2495 * the session 'child' itself dies 2496 */ 2497 void 2498 session_close_by_channel(struct ssh *ssh, int id, void *arg) 2499 { 2500 Session *s = session_by_channel(id); 2501 u_int i; 2502 2503 if (s == NULL) { 2504 debug_f("no session for id %d", id); 2505 return; 2506 } 2507 debug_f("channel %d child %ld", id, (long)s->pid); 2508 if (s->pid != 0) { 2509 debug_f("channel %d: has child, ttyfd %d", id, s->ttyfd); 2510 /* 2511 * delay detach of session, but release pty, since 2512 * the fd's to the child are already closed 2513 */ 2514 if (s->ttyfd != -1) 2515 session_pty_cleanup(s); 2516 return; 2517 } 2518 /* detach by removing callback */ 2519 channel_cancel_cleanup(ssh, s->chanid); 2520 2521 /* Close any X11 listeners associated with this session */ 2522 if (s->x11_chanids != NULL) { 2523 for (i = 0; s->x11_chanids[i] != -1; i++) { 2524 session_close_x11(ssh, s->x11_chanids[i]); 2525 s->x11_chanids[i] = -1; 2526 } 2527 } 2528 2529 s->chanid = -1; 2530 session_close(ssh, s); 2531 } 2532 2533 void 2534 session_destroy_all(struct ssh *ssh, void (*closefunc)(Session *)) 2535 { 2536 int i; 2537 for (i = 0; i < sessions_nalloc; i++) { 2538 Session *s = &sessions[i]; 2539 if (s->used) { 2540 if (closefunc != NULL) 2541 closefunc(s); 2542 else 2543 session_close(ssh, s); 2544 } 2545 } 2546 } 2547 2548 static char * 2549 session_tty_list(void) 2550 { 2551 static char buf[1024]; 2552 int i; 2553 char *cp; 2554 2555 buf[0] = '\0'; 2556 for (i = 0; i < sessions_nalloc; i++) { 2557 Session *s = &sessions[i]; 2558 if (s->used && s->ttyfd != -1) { 2559 2560 if (strncmp(s->tty, "/dev/", 5) != 0) { 2561 cp = strrchr(s->tty, '/'); 2562 cp = (cp == NULL) ? s->tty : cp + 1; 2563 } else 2564 cp = s->tty + 5; 2565 2566 if (buf[0] != '\0') 2567 strlcat(buf, ",", sizeof buf); 2568 strlcat(buf, cp, sizeof buf); 2569 } 2570 } 2571 if (buf[0] == '\0') 2572 strlcpy(buf, "notty", sizeof buf); 2573 return buf; 2574 } 2575 2576 void 2577 session_proctitle(Session *s) 2578 { 2579 if (s->pw == NULL) 2580 error("no user for session %d", s->self); 2581 else 2582 setproctitle("%s@%s", s->pw->pw_name, session_tty_list()); 2583 } 2584 2585 int 2586 session_setup_x11fwd(struct ssh *ssh, Session *s) 2587 { 2588 struct stat st; 2589 char display[512], auth_display[512]; 2590 char hostname[NI_MAXHOST]; 2591 u_int i; 2592 2593 if (!auth_opts->permit_x11_forwarding_flag) { 2594 ssh_packet_send_debug(ssh, "X11 forwarding disabled by key options."); 2595 return 0; 2596 } 2597 if (!options.x11_forwarding) { 2598 debug("X11 forwarding disabled in server configuration file."); 2599 return 0; 2600 } 2601 if (options.xauth_location == NULL || 2602 (stat(options.xauth_location, &st) == -1)) { 2603 ssh_packet_send_debug(ssh, "No xauth program; cannot forward X11."); 2604 return 0; 2605 } 2606 if (s->display != NULL) { 2607 debug("X11 display already set."); 2608 return 0; 2609 } 2610 if (x11_create_display_inet(ssh, options.x11_display_offset, 2611 options.x11_use_localhost, s->single_connection, 2612 &s->display_number, &s->x11_chanids) == -1) { 2613 debug("x11_create_display_inet failed."); 2614 return 0; 2615 } 2616 for (i = 0; s->x11_chanids[i] != -1; i++) { 2617 channel_register_cleanup(ssh, s->x11_chanids[i], 2618 session_close_single_x11, 0); 2619 } 2620 2621 /* Set up a suitable value for the DISPLAY variable. */ 2622 if (gethostname(hostname, sizeof(hostname)) == -1) 2623 fatal("gethostname: %.100s", strerror(errno)); 2624 /* 2625 * auth_display must be used as the displayname when the 2626 * authorization entry is added with xauth(1). This will be 2627 * different than the DISPLAY string for localhost displays. 2628 */ 2629 if (options.x11_use_localhost) { 2630 snprintf(display, sizeof display, "localhost:%u.%u", 2631 s->display_number, s->screen); 2632 snprintf(auth_display, sizeof auth_display, "unix:%u.%u", 2633 s->display_number, s->screen); 2634 s->display = xstrdup(display); 2635 s->auth_display = xstrdup(auth_display); 2636 } else { 2637 #ifdef IPADDR_IN_DISPLAY 2638 struct hostent *he; 2639 struct in_addr my_addr; 2640 2641 he = gethostbyname(hostname); 2642 if (he == NULL) { 2643 error("Can't get IP address for X11 DISPLAY."); 2644 ssh_packet_send_debug(ssh, "Can't get IP address for X11 DISPLAY."); 2645 return 0; 2646 } 2647 memcpy(&my_addr, he->h_addr_list[0], sizeof(struct in_addr)); 2648 snprintf(display, sizeof display, "%.50s:%u.%u", inet_ntoa(my_addr), 2649 s->display_number, s->screen); 2650 #else 2651 snprintf(display, sizeof display, "%.400s:%u.%u", hostname, 2652 s->display_number, s->screen); 2653 #endif 2654 s->display = xstrdup(display); 2655 s->auth_display = xstrdup(display); 2656 } 2657 2658 return 1; 2659 } 2660 2661 static void 2662 do_authenticated2(struct ssh *ssh, Authctxt *authctxt) 2663 { 2664 server_loop2(ssh, authctxt); 2665 } 2666 2667 void 2668 do_cleanup(struct ssh *ssh, Authctxt *authctxt) 2669 { 2670 static int called = 0; 2671 2672 debug("do_cleanup"); 2673 2674 /* no cleanup if we're in the child for login shell */ 2675 if (is_child) 2676 return; 2677 2678 /* avoid double cleanup */ 2679 if (called) 2680 return; 2681 called = 1; 2682 2683 if (authctxt == NULL) 2684 return; 2685 2686 #ifdef USE_PAM 2687 if (options.use_pam) { 2688 sshpam_cleanup(); 2689 sshpam_thread_cleanup(); 2690 } 2691 #endif 2692 2693 if (!authctxt->authenticated) 2694 return; 2695 2696 #ifdef KRB5 2697 if (options.kerberos_ticket_cleanup && 2698 authctxt->krb5_ctx) 2699 krb5_cleanup_proc(authctxt); 2700 #endif 2701 2702 #ifdef GSSAPI 2703 if (options.gss_cleanup_creds) 2704 ssh_gssapi_cleanup_creds(); 2705 #endif 2706 2707 /* remove agent socket */ 2708 auth_sock_cleanup_proc(authctxt->pw); 2709 2710 /* remove userauth info */ 2711 if (auth_info_file != NULL) { 2712 temporarily_use_uid(authctxt->pw); 2713 unlink(auth_info_file); 2714 restore_uid(); 2715 free(auth_info_file); 2716 auth_info_file = NULL; 2717 } 2718 2719 /* 2720 * Cleanup ptys/utmp only if privsep is disabled, 2721 * or if running in monitor. 2722 */ 2723 if (!use_privsep || mm_is_monitor()) 2724 session_destroy_all(ssh, session_pty_cleanup2); 2725 } 2726 2727 /* Return a name for the remote host that fits inside utmp_size */ 2728 2729 const char * 2730 session_get_remote_name_or_ip(struct ssh *ssh, u_int utmp_size, int use_dns) 2731 { 2732 const char *remote = ""; 2733 2734 if (utmp_size > 0) 2735 remote = auth_get_canonical_hostname(ssh, use_dns); 2736 if (utmp_size == 0 || strlen(remote) > utmp_size) 2737 remote = ssh_remote_ipaddr(ssh); 2738 return remote; 2739 } 2740 2741