1 /* $OpenBSD: session.c,v 1.315 2019/02/22 03:37:11 djm Exp $ */ 2 /* 3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 4 * All rights reserved 5 * 6 * As far as I am concerned, the code I have written for this software 7 * can be used freely for any purpose. Any derived versions of this 8 * software must be clearly marked as such, and if the derived work is 9 * incompatible with the protocol description in the RFC file, it must be 10 * called by a name other than "ssh" or "Secure Shell". 11 * 12 * SSH2 support by Markus Friedl. 13 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 14 * 15 * Redistribution and use in source and binary forms, with or without 16 * modification, are permitted provided that the following conditions 17 * are met: 18 * 1. Redistributions of source code must retain the above copyright 19 * notice, this list of conditions and the following disclaimer. 20 * 2. Redistributions in binary form must reproduce the above copyright 21 * notice, this list of conditions and the following disclaimer in the 22 * documentation and/or other materials provided with the distribution. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 25 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 26 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 27 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 28 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 29 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 30 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 31 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 32 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 33 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 34 */ 35 36 #include "includes.h" 37 38 #include <sys/types.h> 39 #include <sys/param.h> 40 #ifdef HAVE_SYS_STAT_H 41 # include <sys/stat.h> 42 #endif 43 #include <sys/socket.h> 44 #include <sys/un.h> 45 #include <sys/wait.h> 46 47 #include <arpa/inet.h> 48 49 #include <ctype.h> 50 #include <errno.h> 51 #include <fcntl.h> 52 #include <grp.h> 53 #include <netdb.h> 54 #ifdef HAVE_PATHS_H 55 #include <paths.h> 56 #endif 57 #include <pwd.h> 58 #include <signal.h> 59 #include <stdarg.h> 60 #include <stdio.h> 61 #include <stdlib.h> 62 #include <string.h> 63 #include <unistd.h> 64 #include <limits.h> 65 66 #include "openbsd-compat/sys-queue.h" 67 #include "xmalloc.h" 68 #include "ssh.h" 69 #include "ssh2.h" 70 #include "sshpty.h" 71 #include "packet.h" 72 #include "sshbuf.h" 73 #include "ssherr.h" 74 #include "match.h" 75 #include "uidswap.h" 76 #include "compat.h" 77 #include "channels.h" 78 #include "sshkey.h" 79 #include "cipher.h" 80 #ifdef GSSAPI 81 #include "ssh-gss.h" 82 #endif 83 #include "hostfile.h" 84 #include "auth.h" 85 #include "auth-options.h" 86 #include "authfd.h" 87 #include "pathnames.h" 88 #include "log.h" 89 #include "misc.h" 90 #include "servconf.h" 91 #include "sshlogin.h" 92 #include "serverloop.h" 93 #include "canohost.h" 94 #include "session.h" 95 #include "kex.h" 96 #include "monitor_wrap.h" 97 #include "sftp.h" 98 #include "atomicio.h" 99 100 #if defined(KRB5) && defined(USE_AFS) 101 #include <kafs.h> 102 #endif 103 104 #ifdef WITH_SELINUX 105 #include <selinux/selinux.h> 106 #endif 107 108 #define IS_INTERNAL_SFTP(c) \ 109 (!strncmp(c, INTERNAL_SFTP_NAME, sizeof(INTERNAL_SFTP_NAME) - 1) && \ 110 (c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\0' || \ 111 c[sizeof(INTERNAL_SFTP_NAME) - 1] == ' ' || \ 112 c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\t')) 113 114 /* func */ 115 116 Session *session_new(void); 117 void session_set_fds(struct ssh *, Session *, int, int, int, int, int); 118 void session_pty_cleanup(Session *); 119 void session_proctitle(Session *); 120 int session_setup_x11fwd(struct ssh *, Session *); 121 int do_exec_pty(struct ssh *, Session *, const char *); 122 int do_exec_no_pty(struct ssh *, Session *, const char *); 123 int do_exec(struct ssh *, Session *, const char *); 124 void do_login(struct ssh *, Session *, const char *); 125 void do_child(struct ssh *, Session *, const char *); 126 void do_motd(void); 127 int check_quietlogin(Session *, const char *); 128 129 static void do_authenticated2(struct ssh *, Authctxt *); 130 131 static int session_pty_req(struct ssh *, Session *); 132 133 /* import */ 134 extern ServerOptions options; 135 extern char *__progname; 136 extern int debug_flag; 137 extern u_int utmp_len; 138 extern int startup_pipe; 139 extern void destroy_sensitive_data(void); 140 extern struct sshbuf *loginmsg; 141 extern struct sshauthopt *auth_opts; 142 extern char *tun_fwd_ifnames; /* serverloop.c */ 143 144 /* original command from peer. */ 145 const char *original_command = NULL; 146 147 /* data */ 148 static int sessions_first_unused = -1; 149 static int sessions_nalloc = 0; 150 static Session *sessions = NULL; 151 152 #define SUBSYSTEM_NONE 0 153 #define SUBSYSTEM_EXT 1 154 #define SUBSYSTEM_INT_SFTP 2 155 #define SUBSYSTEM_INT_SFTP_ERROR 3 156 157 #ifdef HAVE_LOGIN_CAP 158 login_cap_t *lc; 159 #endif 160 161 static int is_child = 0; 162 static int in_chroot = 0; 163 164 /* File containing userauth info, if ExposeAuthInfo set */ 165 static char *auth_info_file = NULL; 166 167 /* Name and directory of socket for authentication agent forwarding. */ 168 static char *auth_sock_name = NULL; 169 static char *auth_sock_dir = NULL; 170 171 /* removes the agent forwarding socket */ 172 173 static void 174 auth_sock_cleanup_proc(struct passwd *pw) 175 { 176 if (auth_sock_name != NULL) { 177 temporarily_use_uid(pw); 178 unlink(auth_sock_name); 179 rmdir(auth_sock_dir); 180 auth_sock_name = NULL; 181 restore_uid(); 182 } 183 } 184 185 static int 186 auth_input_request_forwarding(struct ssh *ssh, struct passwd * pw) 187 { 188 Channel *nc; 189 int sock = -1; 190 191 if (auth_sock_name != NULL) { 192 error("authentication forwarding requested twice."); 193 return 0; 194 } 195 196 /* Temporarily drop privileged uid for mkdir/bind. */ 197 temporarily_use_uid(pw); 198 199 /* Allocate a buffer for the socket name, and format the name. */ 200 auth_sock_dir = xstrdup("/tmp/ssh-XXXXXXXXXX"); 201 202 /* Create private directory for socket */ 203 if (mkdtemp(auth_sock_dir) == NULL) { 204 ssh_packet_send_debug(ssh, "Agent forwarding disabled: " 205 "mkdtemp() failed: %.100s", strerror(errno)); 206 restore_uid(); 207 free(auth_sock_dir); 208 auth_sock_dir = NULL; 209 goto authsock_err; 210 } 211 212 xasprintf(&auth_sock_name, "%s/agent.%ld", 213 auth_sock_dir, (long) getpid()); 214 215 /* Start a Unix listener on auth_sock_name. */ 216 sock = unix_listener(auth_sock_name, SSH_LISTEN_BACKLOG, 0); 217 218 /* Restore the privileged uid. */ 219 restore_uid(); 220 221 /* Check for socket/bind/listen failure. */ 222 if (sock < 0) 223 goto authsock_err; 224 225 /* Allocate a channel for the authentication agent socket. */ 226 nc = channel_new(ssh, "auth socket", 227 SSH_CHANNEL_AUTH_SOCKET, sock, sock, -1, 228 CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 229 0, "auth socket", 1); 230 nc->path = xstrdup(auth_sock_name); 231 return 1; 232 233 authsock_err: 234 free(auth_sock_name); 235 if (auth_sock_dir != NULL) { 236 temporarily_use_uid(pw); 237 rmdir(auth_sock_dir); 238 restore_uid(); 239 free(auth_sock_dir); 240 } 241 if (sock != -1) 242 close(sock); 243 auth_sock_name = NULL; 244 auth_sock_dir = NULL; 245 return 0; 246 } 247 248 static void 249 display_loginmsg(void) 250 { 251 int r; 252 253 if (sshbuf_len(loginmsg) == 0) 254 return; 255 if ((r = sshbuf_put_u8(loginmsg, 0)) != 0) 256 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 257 printf("%s", (char *)sshbuf_ptr(loginmsg)); 258 sshbuf_reset(loginmsg); 259 } 260 261 static void 262 prepare_auth_info_file(struct passwd *pw, struct sshbuf *info) 263 { 264 int fd = -1, success = 0; 265 266 if (!options.expose_userauth_info || info == NULL) 267 return; 268 269 temporarily_use_uid(pw); 270 auth_info_file = xstrdup("/tmp/sshauth.XXXXXXXXXXXXXXX"); 271 if ((fd = mkstemp(auth_info_file)) == -1) { 272 error("%s: mkstemp: %s", __func__, strerror(errno)); 273 goto out; 274 } 275 if (atomicio(vwrite, fd, sshbuf_mutable_ptr(info), 276 sshbuf_len(info)) != sshbuf_len(info)) { 277 error("%s: write: %s", __func__, strerror(errno)); 278 goto out; 279 } 280 if (close(fd) != 0) { 281 error("%s: close: %s", __func__, strerror(errno)); 282 goto out; 283 } 284 success = 1; 285 out: 286 if (!success) { 287 if (fd != -1) 288 close(fd); 289 free(auth_info_file); 290 auth_info_file = NULL; 291 } 292 restore_uid(); 293 } 294 295 static void 296 set_fwdpermit_from_authopts(struct ssh *ssh, const struct sshauthopt *opts) 297 { 298 char *tmp, *cp, *host; 299 int port; 300 size_t i; 301 302 if ((options.allow_tcp_forwarding & FORWARD_LOCAL) != 0) { 303 channel_clear_permission(ssh, FORWARD_USER, FORWARD_LOCAL); 304 for (i = 0; i < auth_opts->npermitopen; i++) { 305 tmp = cp = xstrdup(auth_opts->permitopen[i]); 306 /* This shouldn't fail as it has already been checked */ 307 if ((host = hpdelim(&cp)) == NULL) 308 fatal("%s: internal error: hpdelim", __func__); 309 host = cleanhostname(host); 310 if (cp == NULL || (port = permitopen_port(cp)) < 0) 311 fatal("%s: internal error: permitopen port", 312 __func__); 313 channel_add_permission(ssh, 314 FORWARD_USER, FORWARD_LOCAL, host, port); 315 free(tmp); 316 } 317 } 318 if ((options.allow_tcp_forwarding & FORWARD_REMOTE) != 0) { 319 channel_clear_permission(ssh, FORWARD_USER, FORWARD_REMOTE); 320 for (i = 0; i < auth_opts->npermitlisten; i++) { 321 tmp = cp = xstrdup(auth_opts->permitlisten[i]); 322 /* This shouldn't fail as it has already been checked */ 323 if ((host = hpdelim(&cp)) == NULL) 324 fatal("%s: internal error: hpdelim", __func__); 325 host = cleanhostname(host); 326 if (cp == NULL || (port = permitopen_port(cp)) < 0) 327 fatal("%s: internal error: permitlisten port", 328 __func__); 329 channel_add_permission(ssh, 330 FORWARD_USER, FORWARD_REMOTE, host, port); 331 free(tmp); 332 } 333 } 334 } 335 336 void 337 do_authenticated(struct ssh *ssh, Authctxt *authctxt) 338 { 339 setproctitle("%s", authctxt->pw->pw_name); 340 341 auth_log_authopts("active", auth_opts, 0); 342 343 /* setup the channel layer */ 344 /* XXX - streamlocal? */ 345 set_fwdpermit_from_authopts(ssh, auth_opts); 346 347 if (!auth_opts->permit_port_forwarding_flag || 348 options.disable_forwarding) { 349 channel_disable_admin(ssh, FORWARD_LOCAL); 350 channel_disable_admin(ssh, FORWARD_REMOTE); 351 } else { 352 if ((options.allow_tcp_forwarding & FORWARD_LOCAL) == 0) 353 channel_disable_admin(ssh, FORWARD_LOCAL); 354 else 355 channel_permit_all(ssh, FORWARD_LOCAL); 356 if ((options.allow_tcp_forwarding & FORWARD_REMOTE) == 0) 357 channel_disable_admin(ssh, FORWARD_REMOTE); 358 else 359 channel_permit_all(ssh, FORWARD_REMOTE); 360 } 361 auth_debug_send(ssh); 362 363 prepare_auth_info_file(authctxt->pw, authctxt->session_info); 364 365 do_authenticated2(ssh, authctxt); 366 367 do_cleanup(ssh, authctxt); 368 } 369 370 /* Check untrusted xauth strings for metacharacters */ 371 static int 372 xauth_valid_string(const char *s) 373 { 374 size_t i; 375 376 for (i = 0; s[i] != '\0'; i++) { 377 if (!isalnum((u_char)s[i]) && 378 s[i] != '.' && s[i] != ':' && s[i] != '/' && 379 s[i] != '-' && s[i] != '_') 380 return 0; 381 } 382 return 1; 383 } 384 385 #define USE_PIPES 1 386 /* 387 * This is called to fork and execute a command when we have no tty. This 388 * will call do_child from the child, and server_loop from the parent after 389 * setting up file descriptors and such. 390 */ 391 int 392 do_exec_no_pty(struct ssh *ssh, Session *s, const char *command) 393 { 394 pid_t pid; 395 #ifdef USE_PIPES 396 int pin[2], pout[2], perr[2]; 397 398 if (s == NULL) 399 fatal("do_exec_no_pty: no session"); 400 401 /* Allocate pipes for communicating with the program. */ 402 if (pipe(pin) < 0) { 403 error("%s: pipe in: %.100s", __func__, strerror(errno)); 404 return -1; 405 } 406 if (pipe(pout) < 0) { 407 error("%s: pipe out: %.100s", __func__, strerror(errno)); 408 close(pin[0]); 409 close(pin[1]); 410 return -1; 411 } 412 if (pipe(perr) < 0) { 413 error("%s: pipe err: %.100s", __func__, 414 strerror(errno)); 415 close(pin[0]); 416 close(pin[1]); 417 close(pout[0]); 418 close(pout[1]); 419 return -1; 420 } 421 #else 422 int inout[2], err[2]; 423 424 if (s == NULL) 425 fatal("do_exec_no_pty: no session"); 426 427 /* Uses socket pairs to communicate with the program. */ 428 if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) < 0) { 429 error("%s: socketpair #1: %.100s", __func__, strerror(errno)); 430 return -1; 431 } 432 if (socketpair(AF_UNIX, SOCK_STREAM, 0, err) < 0) { 433 error("%s: socketpair #2: %.100s", __func__, 434 strerror(errno)); 435 close(inout[0]); 436 close(inout[1]); 437 return -1; 438 } 439 #endif 440 441 session_proctitle(s); 442 443 /* Fork the child. */ 444 switch ((pid = fork())) { 445 case -1: 446 error("%s: fork: %.100s", __func__, strerror(errno)); 447 #ifdef USE_PIPES 448 close(pin[0]); 449 close(pin[1]); 450 close(pout[0]); 451 close(pout[1]); 452 close(perr[0]); 453 close(perr[1]); 454 #else 455 close(inout[0]); 456 close(inout[1]); 457 close(err[0]); 458 close(err[1]); 459 #endif 460 return -1; 461 case 0: 462 is_child = 1; 463 464 /* 465 * Create a new session and process group since the 4.4BSD 466 * setlogin() affects the entire process group. 467 */ 468 if (setsid() < 0) 469 error("setsid failed: %.100s", strerror(errno)); 470 471 #ifdef USE_PIPES 472 /* 473 * Redirect stdin. We close the parent side of the socket 474 * pair, and make the child side the standard input. 475 */ 476 close(pin[1]); 477 if (dup2(pin[0], 0) < 0) 478 perror("dup2 stdin"); 479 close(pin[0]); 480 481 /* Redirect stdout. */ 482 close(pout[0]); 483 if (dup2(pout[1], 1) < 0) 484 perror("dup2 stdout"); 485 close(pout[1]); 486 487 /* Redirect stderr. */ 488 close(perr[0]); 489 if (dup2(perr[1], 2) < 0) 490 perror("dup2 stderr"); 491 close(perr[1]); 492 #else 493 /* 494 * Redirect stdin, stdout, and stderr. Stdin and stdout will 495 * use the same socket, as some programs (particularly rdist) 496 * seem to depend on it. 497 */ 498 close(inout[1]); 499 close(err[1]); 500 if (dup2(inout[0], 0) < 0) /* stdin */ 501 perror("dup2 stdin"); 502 if (dup2(inout[0], 1) < 0) /* stdout (same as stdin) */ 503 perror("dup2 stdout"); 504 close(inout[0]); 505 if (dup2(err[0], 2) < 0) /* stderr */ 506 perror("dup2 stderr"); 507 close(err[0]); 508 #endif 509 510 /* Do processing for the child (exec command etc). */ 511 do_child(ssh, s, command); 512 /* NOTREACHED */ 513 default: 514 break; 515 } 516 517 #ifdef HAVE_CYGWIN 518 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); 519 #endif 520 521 s->pid = pid; 522 /* Set interactive/non-interactive mode. */ 523 ssh_packet_set_interactive(ssh, s->display != NULL, 524 options.ip_qos_interactive, options.ip_qos_bulk); 525 526 /* 527 * Clear loginmsg, since it's the child's responsibility to display 528 * it to the user, otherwise multiple sessions may accumulate 529 * multiple copies of the login messages. 530 */ 531 sshbuf_reset(loginmsg); 532 533 #ifdef USE_PIPES 534 /* We are the parent. Close the child sides of the pipes. */ 535 close(pin[0]); 536 close(pout[1]); 537 close(perr[1]); 538 539 session_set_fds(ssh, s, pin[1], pout[0], perr[0], 540 s->is_subsystem, 0); 541 #else 542 /* We are the parent. Close the child sides of the socket pairs. */ 543 close(inout[0]); 544 close(err[0]); 545 546 /* 547 * Enter the interactive session. Note: server_loop must be able to 548 * handle the case that fdin and fdout are the same. 549 */ 550 session_set_fds(ssh, s, inout[1], inout[1], err[1], 551 s->is_subsystem, 0); 552 #endif 553 return 0; 554 } 555 556 /* 557 * This is called to fork and execute a command when we have a tty. This 558 * will call do_child from the child, and server_loop from the parent after 559 * setting up file descriptors, controlling tty, updating wtmp, utmp, 560 * lastlog, and other such operations. 561 */ 562 int 563 do_exec_pty(struct ssh *ssh, Session *s, const char *command) 564 { 565 int fdout, ptyfd, ttyfd, ptymaster; 566 pid_t pid; 567 568 if (s == NULL) 569 fatal("do_exec_pty: no session"); 570 ptyfd = s->ptyfd; 571 ttyfd = s->ttyfd; 572 573 /* 574 * Create another descriptor of the pty master side for use as the 575 * standard input. We could use the original descriptor, but this 576 * simplifies code in server_loop. The descriptor is bidirectional. 577 * Do this before forking (and cleanup in the child) so as to 578 * detect and gracefully fail out-of-fd conditions. 579 */ 580 if ((fdout = dup(ptyfd)) < 0) { 581 error("%s: dup #1: %s", __func__, strerror(errno)); 582 close(ttyfd); 583 close(ptyfd); 584 return -1; 585 } 586 /* we keep a reference to the pty master */ 587 if ((ptymaster = dup(ptyfd)) < 0) { 588 error("%s: dup #2: %s", __func__, strerror(errno)); 589 close(ttyfd); 590 close(ptyfd); 591 close(fdout); 592 return -1; 593 } 594 595 /* Fork the child. */ 596 switch ((pid = fork())) { 597 case -1: 598 error("%s: fork: %.100s", __func__, strerror(errno)); 599 close(fdout); 600 close(ptymaster); 601 close(ttyfd); 602 close(ptyfd); 603 return -1; 604 case 0: 605 is_child = 1; 606 607 close(fdout); 608 close(ptymaster); 609 610 /* Close the master side of the pseudo tty. */ 611 close(ptyfd); 612 613 /* Make the pseudo tty our controlling tty. */ 614 pty_make_controlling_tty(&ttyfd, s->tty); 615 616 /* Redirect stdin/stdout/stderr from the pseudo tty. */ 617 if (dup2(ttyfd, 0) < 0) 618 error("dup2 stdin: %s", strerror(errno)); 619 if (dup2(ttyfd, 1) < 0) 620 error("dup2 stdout: %s", strerror(errno)); 621 if (dup2(ttyfd, 2) < 0) 622 error("dup2 stderr: %s", strerror(errno)); 623 624 /* Close the extra descriptor for the pseudo tty. */ 625 close(ttyfd); 626 627 /* record login, etc. similar to login(1) */ 628 #ifndef HAVE_OSF_SIA 629 do_login(ssh, s, command); 630 #endif 631 /* 632 * Do common processing for the child, such as execing 633 * the command. 634 */ 635 do_child(ssh, s, command); 636 /* NOTREACHED */ 637 default: 638 break; 639 } 640 641 #ifdef HAVE_CYGWIN 642 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); 643 #endif 644 645 s->pid = pid; 646 647 /* Parent. Close the slave side of the pseudo tty. */ 648 close(ttyfd); 649 650 /* Enter interactive session. */ 651 s->ptymaster = ptymaster; 652 ssh_packet_set_interactive(ssh, 1, 653 options.ip_qos_interactive, options.ip_qos_bulk); 654 session_set_fds(ssh, s, ptyfd, fdout, -1, 1, 1); 655 return 0; 656 } 657 658 /* 659 * This is called to fork and execute a command. If another command is 660 * to be forced, execute that instead. 661 */ 662 int 663 do_exec(struct ssh *ssh, Session *s, const char *command) 664 { 665 int ret; 666 const char *forced = NULL, *tty = NULL; 667 char session_type[1024]; 668 669 if (options.adm_forced_command) { 670 original_command = command; 671 command = options.adm_forced_command; 672 forced = "(config)"; 673 } else if (auth_opts->force_command != NULL) { 674 original_command = command; 675 command = auth_opts->force_command; 676 forced = "(key-option)"; 677 } 678 s->forced = 0; 679 if (forced != NULL) { 680 s->forced = 1; 681 if (IS_INTERNAL_SFTP(command)) { 682 s->is_subsystem = s->is_subsystem ? 683 SUBSYSTEM_INT_SFTP : SUBSYSTEM_INT_SFTP_ERROR; 684 } else if (s->is_subsystem) 685 s->is_subsystem = SUBSYSTEM_EXT; 686 snprintf(session_type, sizeof(session_type), 687 "forced-command %s '%.900s'", forced, command); 688 } else if (s->is_subsystem) { 689 snprintf(session_type, sizeof(session_type), 690 "subsystem '%.900s'", s->subsys); 691 } else if (command == NULL) { 692 snprintf(session_type, sizeof(session_type), "shell"); 693 } else { 694 /* NB. we don't log unforced commands to preserve privacy */ 695 snprintf(session_type, sizeof(session_type), "command"); 696 } 697 698 if (s->ttyfd != -1) { 699 tty = s->tty; 700 if (strncmp(tty, "/dev/", 5) == 0) 701 tty += 5; 702 } 703 704 verbose("Starting session: %s%s%s for %s from %.200s port %d id %d", 705 session_type, 706 tty == NULL ? "" : " on ", 707 tty == NULL ? "" : tty, 708 s->pw->pw_name, 709 ssh_remote_ipaddr(ssh), 710 ssh_remote_port(ssh), 711 s->self); 712 713 #ifdef SSH_AUDIT_EVENTS 714 if (command != NULL) 715 PRIVSEP(audit_run_command(command)); 716 else if (s->ttyfd == -1) { 717 char *shell = s->pw->pw_shell; 718 719 if (shell[0] == '\0') /* empty shell means /bin/sh */ 720 shell =_PATH_BSHELL; 721 PRIVSEP(audit_run_command(shell)); 722 } 723 #endif 724 if (s->ttyfd != -1) 725 ret = do_exec_pty(ssh, s, command); 726 else 727 ret = do_exec_no_pty(ssh, s, command); 728 729 original_command = NULL; 730 731 /* 732 * Clear loginmsg: it's the child's responsibility to display 733 * it to the user, otherwise multiple sessions may accumulate 734 * multiple copies of the login messages. 735 */ 736 sshbuf_reset(loginmsg); 737 738 return ret; 739 } 740 741 /* administrative, login(1)-like work */ 742 void 743 do_login(struct ssh *ssh, Session *s, const char *command) 744 { 745 socklen_t fromlen; 746 struct sockaddr_storage from; 747 struct passwd * pw = s->pw; 748 pid_t pid = getpid(); 749 750 /* 751 * Get IP address of client. If the connection is not a socket, let 752 * the address be 0.0.0.0. 753 */ 754 memset(&from, 0, sizeof(from)); 755 fromlen = sizeof(from); 756 if (ssh_packet_connection_is_on_socket(ssh)) { 757 if (getpeername(ssh_packet_get_connection_in(ssh), 758 (struct sockaddr *)&from, &fromlen) < 0) { 759 debug("getpeername: %.100s", strerror(errno)); 760 cleanup_exit(255); 761 } 762 } 763 764 /* Record that there was a login on that tty from the remote host. */ 765 if (!use_privsep) 766 record_login(pid, s->tty, pw->pw_name, pw->pw_uid, 767 session_get_remote_name_or_ip(ssh, utmp_len, 768 options.use_dns), 769 (struct sockaddr *)&from, fromlen); 770 771 #ifdef USE_PAM 772 /* 773 * If password change is needed, do it now. 774 * This needs to occur before the ~/.hushlogin check. 775 */ 776 if (options.use_pam && !use_privsep && s->authctxt->force_pwchange) { 777 display_loginmsg(); 778 do_pam_chauthtok(); 779 s->authctxt->force_pwchange = 0; 780 /* XXX - signal [net] parent to enable forwardings */ 781 } 782 #endif 783 784 if (check_quietlogin(s, command)) 785 return; 786 787 display_loginmsg(); 788 789 do_motd(); 790 } 791 792 /* 793 * Display the message of the day. 794 */ 795 void 796 do_motd(void) 797 { 798 FILE *f; 799 char buf[256]; 800 801 if (options.print_motd) { 802 #ifdef HAVE_LOGIN_CAP 803 f = fopen(login_getcapstr(lc, "welcome", "/etc/motd", 804 "/etc/motd"), "r"); 805 #else 806 f = fopen("/etc/motd", "r"); 807 #endif 808 if (f) { 809 while (fgets(buf, sizeof(buf), f)) 810 fputs(buf, stdout); 811 fclose(f); 812 } 813 } 814 } 815 816 817 /* 818 * Check for quiet login, either .hushlogin or command given. 819 */ 820 int 821 check_quietlogin(Session *s, const char *command) 822 { 823 char buf[256]; 824 struct passwd *pw = s->pw; 825 struct stat st; 826 827 /* Return 1 if .hushlogin exists or a command given. */ 828 if (command != NULL) 829 return 1; 830 snprintf(buf, sizeof(buf), "%.200s/.hushlogin", pw->pw_dir); 831 #ifdef HAVE_LOGIN_CAP 832 if (login_getcapbool(lc, "hushlogin", 0) || stat(buf, &st) >= 0) 833 return 1; 834 #else 835 if (stat(buf, &st) >= 0) 836 return 1; 837 #endif 838 return 0; 839 } 840 841 /* 842 * Reads environment variables from the given file and adds/overrides them 843 * into the environment. If the file does not exist, this does nothing. 844 * Otherwise, it must consist of empty lines, comments (line starts with '#') 845 * and assignments of the form name=value. No other forms are allowed. 846 * If whitelist is not NULL, then it is interpreted as a pattern list and 847 * only variable names that match it will be accepted. 848 */ 849 static void 850 read_environment_file(char ***env, u_int *envsize, 851 const char *filename, const char *whitelist) 852 { 853 FILE *f; 854 char *line = NULL, *cp, *value; 855 size_t linesize = 0; 856 u_int lineno = 0; 857 858 f = fopen(filename, "r"); 859 if (!f) 860 return; 861 862 while (getline(&line, &linesize, f) != -1) { 863 if (++lineno > 1000) 864 fatal("Too many lines in environment file %s", filename); 865 for (cp = line; *cp == ' ' || *cp == '\t'; cp++) 866 ; 867 if (!*cp || *cp == '#' || *cp == '\n') 868 continue; 869 870 cp[strcspn(cp, "\n")] = '\0'; 871 872 value = strchr(cp, '='); 873 if (value == NULL) { 874 fprintf(stderr, "Bad line %u in %.100s\n", lineno, 875 filename); 876 continue; 877 } 878 /* 879 * Replace the equals sign by nul, and advance value to 880 * the value string. 881 */ 882 *value = '\0'; 883 value++; 884 if (whitelist != NULL && 885 match_pattern_list(cp, whitelist, 0) != 1) 886 continue; 887 child_set_env(env, envsize, cp, value); 888 } 889 free(line); 890 fclose(f); 891 } 892 893 #ifdef HAVE_ETC_DEFAULT_LOGIN 894 /* 895 * Return named variable from specified environment, or NULL if not present. 896 */ 897 static char * 898 child_get_env(char **env, const char *name) 899 { 900 int i; 901 size_t len; 902 903 len = strlen(name); 904 for (i=0; env[i] != NULL; i++) 905 if (strncmp(name, env[i], len) == 0 && env[i][len] == '=') 906 return(env[i] + len + 1); 907 return NULL; 908 } 909 910 /* 911 * Read /etc/default/login. 912 * We pick up the PATH (or SUPATH for root) and UMASK. 913 */ 914 static void 915 read_etc_default_login(char ***env, u_int *envsize, uid_t uid) 916 { 917 char **tmpenv = NULL, *var; 918 u_int i, tmpenvsize = 0; 919 u_long mask; 920 921 /* 922 * We don't want to copy the whole file to the child's environment, 923 * so we use a temporary environment and copy the variables we're 924 * interested in. 925 */ 926 read_environment_file(&tmpenv, &tmpenvsize, "/etc/default/login", 927 options.permit_user_env_whitelist); 928 929 if (tmpenv == NULL) 930 return; 931 932 if (uid == 0) 933 var = child_get_env(tmpenv, "SUPATH"); 934 else 935 var = child_get_env(tmpenv, "PATH"); 936 if (var != NULL) 937 child_set_env(env, envsize, "PATH", var); 938 939 if ((var = child_get_env(tmpenv, "UMASK")) != NULL) 940 if (sscanf(var, "%5lo", &mask) == 1) 941 umask((mode_t)mask); 942 943 for (i = 0; tmpenv[i] != NULL; i++) 944 free(tmpenv[i]); 945 free(tmpenv); 946 } 947 #endif /* HAVE_ETC_DEFAULT_LOGIN */ 948 949 static void 950 copy_environment_blacklist(char **source, char ***env, u_int *envsize, 951 const char *blacklist) 952 { 953 char *var_name, *var_val; 954 int i; 955 956 if (source == NULL) 957 return; 958 959 for(i = 0; source[i] != NULL; i++) { 960 var_name = xstrdup(source[i]); 961 if ((var_val = strstr(var_name, "=")) == NULL) { 962 free(var_name); 963 continue; 964 } 965 *var_val++ = '\0'; 966 967 if (blacklist == NULL || 968 match_pattern_list(var_name, blacklist, 0) != 1) { 969 debug3("Copy environment: %s=%s", var_name, var_val); 970 child_set_env(env, envsize, var_name, var_val); 971 } 972 973 free(var_name); 974 } 975 } 976 977 void 978 copy_environment(char **source, char ***env, u_int *envsize) 979 { 980 copy_environment_blacklist(source, env, envsize, NULL); 981 } 982 983 static char ** 984 do_setup_env(struct ssh *ssh, Session *s, const char *shell) 985 { 986 char buf[256]; 987 size_t n; 988 u_int i, envsize; 989 char *ocp, *cp, *value, **env, *laddr; 990 struct passwd *pw = s->pw; 991 #if !defined (HAVE_LOGIN_CAP) && !defined (HAVE_CYGWIN) 992 char *path = NULL; 993 #endif 994 995 /* Initialize the environment. */ 996 envsize = 100; 997 env = xcalloc(envsize, sizeof(char *)); 998 env[0] = NULL; 999 1000 #ifdef HAVE_CYGWIN 1001 /* 1002 * The Windows environment contains some setting which are 1003 * important for a running system. They must not be dropped. 1004 */ 1005 { 1006 char **p; 1007 1008 p = fetch_windows_environment(); 1009 copy_environment(p, &env, &envsize); 1010 free_windows_environment(p); 1011 } 1012 #endif 1013 1014 #ifdef GSSAPI 1015 /* Allow any GSSAPI methods that we've used to alter 1016 * the childs environment as they see fit 1017 */ 1018 ssh_gssapi_do_child(&env, &envsize); 1019 #endif 1020 1021 /* Set basic environment. */ 1022 for (i = 0; i < s->num_env; i++) 1023 child_set_env(&env, &envsize, s->env[i].name, s->env[i].val); 1024 1025 child_set_env(&env, &envsize, "USER", pw->pw_name); 1026 child_set_env(&env, &envsize, "LOGNAME", pw->pw_name); 1027 #ifdef _AIX 1028 child_set_env(&env, &envsize, "LOGIN", pw->pw_name); 1029 #endif 1030 child_set_env(&env, &envsize, "HOME", pw->pw_dir); 1031 #ifdef HAVE_LOGIN_CAP 1032 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETPATH) < 0) 1033 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); 1034 else 1035 child_set_env(&env, &envsize, "PATH", getenv("PATH")); 1036 #else /* HAVE_LOGIN_CAP */ 1037 # ifndef HAVE_CYGWIN 1038 /* 1039 * There's no standard path on Windows. The path contains 1040 * important components pointing to the system directories, 1041 * needed for loading shared libraries. So the path better 1042 * remains intact here. 1043 */ 1044 # ifdef HAVE_ETC_DEFAULT_LOGIN 1045 read_etc_default_login(&env, &envsize, pw->pw_uid); 1046 path = child_get_env(env, "PATH"); 1047 # endif /* HAVE_ETC_DEFAULT_LOGIN */ 1048 if (path == NULL || *path == '\0') { 1049 child_set_env(&env, &envsize, "PATH", 1050 s->pw->pw_uid == 0 ? SUPERUSER_PATH : _PATH_STDPATH); 1051 } 1052 # endif /* HAVE_CYGWIN */ 1053 #endif /* HAVE_LOGIN_CAP */ 1054 1055 if (!options.use_pam) { 1056 snprintf(buf, sizeof buf, "%.200s/%.50s", 1057 _PATH_MAILDIR, pw->pw_name); 1058 child_set_env(&env, &envsize, "MAIL", buf); 1059 } 1060 1061 /* Normal systems set SHELL by default. */ 1062 child_set_env(&env, &envsize, "SHELL", shell); 1063 1064 if (getenv("TZ")) 1065 child_set_env(&env, &envsize, "TZ", getenv("TZ")); 1066 if (s->term) 1067 child_set_env(&env, &envsize, "TERM", s->term); 1068 if (s->display) 1069 child_set_env(&env, &envsize, "DISPLAY", s->display); 1070 1071 /* 1072 * Since we clear KRB5CCNAME at startup, if it's set now then it 1073 * must have been set by a native authentication method (eg AIX or 1074 * SIA), so copy it to the child. 1075 */ 1076 { 1077 char *cp; 1078 1079 if ((cp = getenv("KRB5CCNAME")) != NULL) 1080 child_set_env(&env, &envsize, "KRB5CCNAME", cp); 1081 } 1082 1083 #ifdef _AIX 1084 { 1085 char *cp; 1086 1087 if ((cp = getenv("AUTHSTATE")) != NULL) 1088 child_set_env(&env, &envsize, "AUTHSTATE", cp); 1089 read_environment_file(&env, &envsize, "/etc/environment", 1090 options.permit_user_env_whitelist); 1091 } 1092 #endif 1093 #ifdef KRB5 1094 if (s->authctxt->krb5_ccname) 1095 child_set_env(&env, &envsize, "KRB5CCNAME", 1096 s->authctxt->krb5_ccname); 1097 #endif 1098 if (auth_sock_name != NULL) 1099 child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME, 1100 auth_sock_name); 1101 1102 1103 /* Set custom environment options from pubkey authentication. */ 1104 if (options.permit_user_env) { 1105 for (n = 0 ; n < auth_opts->nenv; n++) { 1106 ocp = xstrdup(auth_opts->env[n]); 1107 cp = strchr(ocp, '='); 1108 if (*cp == '=') { 1109 *cp = '\0'; 1110 /* Apply PermitUserEnvironment whitelist */ 1111 if (options.permit_user_env_whitelist == NULL || 1112 match_pattern_list(ocp, 1113 options.permit_user_env_whitelist, 0) == 1) 1114 child_set_env(&env, &envsize, 1115 ocp, cp + 1); 1116 } 1117 free(ocp); 1118 } 1119 } 1120 1121 /* read $HOME/.ssh/environment. */ 1122 if (options.permit_user_env) { 1123 snprintf(buf, sizeof buf, "%.200s/.ssh/environment", 1124 pw->pw_dir); 1125 read_environment_file(&env, &envsize, buf, 1126 options.permit_user_env_whitelist); 1127 } 1128 1129 #ifdef USE_PAM 1130 /* 1131 * Pull in any environment variables that may have 1132 * been set by PAM. 1133 */ 1134 if (options.use_pam) { 1135 char **p; 1136 1137 /* 1138 * Don't allow PAM-internal env vars to leak 1139 * back into the session environment. 1140 */ 1141 #define PAM_ENV_BLACKLIST "SSH_AUTH_INFO*,SSH_CONNECTION*" 1142 p = fetch_pam_child_environment(); 1143 copy_environment_blacklist(p, &env, &envsize, 1144 PAM_ENV_BLACKLIST); 1145 free_pam_environment(p); 1146 1147 p = fetch_pam_environment(); 1148 copy_environment_blacklist(p, &env, &envsize, 1149 PAM_ENV_BLACKLIST); 1150 free_pam_environment(p); 1151 } 1152 #endif /* USE_PAM */ 1153 1154 /* Environment specified by admin */ 1155 for (i = 0; i < options.num_setenv; i++) { 1156 cp = xstrdup(options.setenv[i]); 1157 if ((value = strchr(cp, '=')) == NULL) { 1158 /* shouldn't happen; vars are checked in servconf.c */ 1159 fatal("Invalid config SetEnv: %s", options.setenv[i]); 1160 } 1161 *value++ = '\0'; 1162 child_set_env(&env, &envsize, cp, value); 1163 } 1164 1165 /* SSH_CLIENT deprecated */ 1166 snprintf(buf, sizeof buf, "%.50s %d %d", 1167 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 1168 ssh_local_port(ssh)); 1169 child_set_env(&env, &envsize, "SSH_CLIENT", buf); 1170 1171 laddr = get_local_ipaddr(ssh_packet_get_connection_in(ssh)); 1172 snprintf(buf, sizeof buf, "%.50s %d %.50s %d", 1173 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 1174 laddr, ssh_local_port(ssh)); 1175 free(laddr); 1176 child_set_env(&env, &envsize, "SSH_CONNECTION", buf); 1177 1178 if (tun_fwd_ifnames != NULL) 1179 child_set_env(&env, &envsize, "SSH_TUNNEL", tun_fwd_ifnames); 1180 if (auth_info_file != NULL) 1181 child_set_env(&env, &envsize, "SSH_USER_AUTH", auth_info_file); 1182 if (s->ttyfd != -1) 1183 child_set_env(&env, &envsize, "SSH_TTY", s->tty); 1184 if (original_command) 1185 child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND", 1186 original_command); 1187 1188 if (debug_flag) { 1189 /* dump the environment */ 1190 fprintf(stderr, "Environment:\n"); 1191 for (i = 0; env[i]; i++) 1192 fprintf(stderr, " %.200s\n", env[i]); 1193 } 1194 return env; 1195 } 1196 1197 /* 1198 * Run $HOME/.ssh/rc, /etc/ssh/sshrc, or xauth (whichever is found 1199 * first in this order). 1200 */ 1201 static void 1202 do_rc_files(struct ssh *ssh, Session *s, const char *shell) 1203 { 1204 FILE *f = NULL; 1205 char cmd[1024]; 1206 int do_xauth; 1207 struct stat st; 1208 1209 do_xauth = 1210 s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL; 1211 1212 /* ignore _PATH_SSH_USER_RC for subsystems and admin forced commands */ 1213 if (!s->is_subsystem && options.adm_forced_command == NULL && 1214 auth_opts->permit_user_rc && options.permit_user_rc && 1215 stat(_PATH_SSH_USER_RC, &st) >= 0) { 1216 snprintf(cmd, sizeof cmd, "%s -c '%s %s'", 1217 shell, _PATH_BSHELL, _PATH_SSH_USER_RC); 1218 if (debug_flag) 1219 fprintf(stderr, "Running %s\n", cmd); 1220 f = popen(cmd, "w"); 1221 if (f) { 1222 if (do_xauth) 1223 fprintf(f, "%s %s\n", s->auth_proto, 1224 s->auth_data); 1225 pclose(f); 1226 } else 1227 fprintf(stderr, "Could not run %s\n", 1228 _PATH_SSH_USER_RC); 1229 } else if (stat(_PATH_SSH_SYSTEM_RC, &st) >= 0) { 1230 if (debug_flag) 1231 fprintf(stderr, "Running %s %s\n", _PATH_BSHELL, 1232 _PATH_SSH_SYSTEM_RC); 1233 f = popen(_PATH_BSHELL " " _PATH_SSH_SYSTEM_RC, "w"); 1234 if (f) { 1235 if (do_xauth) 1236 fprintf(f, "%s %s\n", s->auth_proto, 1237 s->auth_data); 1238 pclose(f); 1239 } else 1240 fprintf(stderr, "Could not run %s\n", 1241 _PATH_SSH_SYSTEM_RC); 1242 } else if (do_xauth && options.xauth_location != NULL) { 1243 /* Add authority data to .Xauthority if appropriate. */ 1244 if (debug_flag) { 1245 fprintf(stderr, 1246 "Running %.500s remove %.100s\n", 1247 options.xauth_location, s->auth_display); 1248 fprintf(stderr, 1249 "%.500s add %.100s %.100s %.100s\n", 1250 options.xauth_location, s->auth_display, 1251 s->auth_proto, s->auth_data); 1252 } 1253 snprintf(cmd, sizeof cmd, "%s -q -", 1254 options.xauth_location); 1255 f = popen(cmd, "w"); 1256 if (f) { 1257 fprintf(f, "remove %s\n", 1258 s->auth_display); 1259 fprintf(f, "add %s %s %s\n", 1260 s->auth_display, s->auth_proto, 1261 s->auth_data); 1262 pclose(f); 1263 } else { 1264 fprintf(stderr, "Could not run %s\n", 1265 cmd); 1266 } 1267 } 1268 } 1269 1270 static void 1271 do_nologin(struct passwd *pw) 1272 { 1273 FILE *f = NULL; 1274 char buf[1024], *nl, *def_nl = _PATH_NOLOGIN; 1275 struct stat sb; 1276 1277 #ifdef HAVE_LOGIN_CAP 1278 if (login_getcapbool(lc, "ignorenologin", 0) || pw->pw_uid == 0) 1279 return; 1280 nl = login_getcapstr(lc, "nologin", def_nl, def_nl); 1281 #else 1282 if (pw->pw_uid == 0) 1283 return; 1284 nl = def_nl; 1285 #endif 1286 if (stat(nl, &sb) == -1) { 1287 if (nl != def_nl) 1288 free(nl); 1289 return; 1290 } 1291 1292 /* /etc/nologin exists. Print its contents if we can and exit. */ 1293 logit("User %.100s not allowed because %s exists", pw->pw_name, nl); 1294 if ((f = fopen(nl, "r")) != NULL) { 1295 while (fgets(buf, sizeof(buf), f)) 1296 fputs(buf, stderr); 1297 fclose(f); 1298 } 1299 exit(254); 1300 } 1301 1302 /* 1303 * Chroot into a directory after checking it for safety: all path components 1304 * must be root-owned directories with strict permissions. 1305 */ 1306 static void 1307 safely_chroot(const char *path, uid_t uid) 1308 { 1309 const char *cp; 1310 char component[PATH_MAX]; 1311 struct stat st; 1312 1313 if (!path_absolute(path)) 1314 fatal("chroot path does not begin at root"); 1315 if (strlen(path) >= sizeof(component)) 1316 fatal("chroot path too long"); 1317 1318 /* 1319 * Descend the path, checking that each component is a 1320 * root-owned directory with strict permissions. 1321 */ 1322 for (cp = path; cp != NULL;) { 1323 if ((cp = strchr(cp, '/')) == NULL) 1324 strlcpy(component, path, sizeof(component)); 1325 else { 1326 cp++; 1327 memcpy(component, path, cp - path); 1328 component[cp - path] = '\0'; 1329 } 1330 1331 debug3("%s: checking '%s'", __func__, component); 1332 1333 if (stat(component, &st) != 0) 1334 fatal("%s: stat(\"%s\"): %s", __func__, 1335 component, strerror(errno)); 1336 if (st.st_uid != 0 || (st.st_mode & 022) != 0) 1337 fatal("bad ownership or modes for chroot " 1338 "directory %s\"%s\"", 1339 cp == NULL ? "" : "component ", component); 1340 if (!S_ISDIR(st.st_mode)) 1341 fatal("chroot path %s\"%s\" is not a directory", 1342 cp == NULL ? "" : "component ", component); 1343 1344 } 1345 1346 if (chdir(path) == -1) 1347 fatal("Unable to chdir to chroot path \"%s\": " 1348 "%s", path, strerror(errno)); 1349 if (chroot(path) == -1) 1350 fatal("chroot(\"%s\"): %s", path, strerror(errno)); 1351 if (chdir("/") == -1) 1352 fatal("%s: chdir(/) after chroot: %s", 1353 __func__, strerror(errno)); 1354 verbose("Changed root directory to \"%s\"", path); 1355 } 1356 1357 /* Set login name, uid, gid, and groups. */ 1358 void 1359 do_setusercontext(struct passwd *pw) 1360 { 1361 char uidstr[32], *chroot_path, *tmp; 1362 1363 platform_setusercontext(pw); 1364 1365 if (platform_privileged_uidswap()) { 1366 #ifdef HAVE_LOGIN_CAP 1367 if (setusercontext(lc, pw, pw->pw_uid, 1368 (LOGIN_SETALL & ~(LOGIN_SETPATH|LOGIN_SETUSER))) < 0) { 1369 perror("unable to set user context"); 1370 exit(1); 1371 } 1372 #else 1373 if (setlogin(pw->pw_name) < 0) 1374 error("setlogin failed: %s", strerror(errno)); 1375 if (setgid(pw->pw_gid) < 0) { 1376 perror("setgid"); 1377 exit(1); 1378 } 1379 /* Initialize the group list. */ 1380 if (initgroups(pw->pw_name, pw->pw_gid) < 0) { 1381 perror("initgroups"); 1382 exit(1); 1383 } 1384 endgrent(); 1385 #endif 1386 1387 platform_setusercontext_post_groups(pw); 1388 1389 if (!in_chroot && options.chroot_directory != NULL && 1390 strcasecmp(options.chroot_directory, "none") != 0) { 1391 tmp = tilde_expand_filename(options.chroot_directory, 1392 pw->pw_uid); 1393 snprintf(uidstr, sizeof(uidstr), "%llu", 1394 (unsigned long long)pw->pw_uid); 1395 chroot_path = percent_expand(tmp, "h", pw->pw_dir, 1396 "u", pw->pw_name, "U", uidstr, (char *)NULL); 1397 safely_chroot(chroot_path, pw->pw_uid); 1398 free(tmp); 1399 free(chroot_path); 1400 /* Make sure we don't attempt to chroot again */ 1401 free(options.chroot_directory); 1402 options.chroot_directory = NULL; 1403 in_chroot = 1; 1404 } 1405 1406 #ifdef HAVE_LOGIN_CAP 1407 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUSER) < 0) { 1408 perror("unable to set user context (setuser)"); 1409 exit(1); 1410 } 1411 /* 1412 * FreeBSD's setusercontext() will not apply the user's 1413 * own umask setting unless running with the user's UID. 1414 */ 1415 (void) setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUMASK); 1416 #else 1417 # ifdef USE_LIBIAF 1418 /* 1419 * In a chroot environment, the set_id() will always fail; 1420 * typically because of the lack of necessary authentication 1421 * services and runtime such as ./usr/lib/libiaf.so, 1422 * ./usr/lib/libpam.so.1, and ./etc/passwd We skip it in the 1423 * internal sftp chroot case. We'll lose auditing and ACLs but 1424 * permanently_set_uid will take care of the rest. 1425 */ 1426 if (!in_chroot && set_id(pw->pw_name) != 0) 1427 fatal("set_id(%s) Failed", pw->pw_name); 1428 # endif /* USE_LIBIAF */ 1429 /* Permanently switch to the desired uid. */ 1430 permanently_set_uid(pw); 1431 #endif 1432 } else if (options.chroot_directory != NULL && 1433 strcasecmp(options.chroot_directory, "none") != 0) { 1434 fatal("server lacks privileges to chroot to ChrootDirectory"); 1435 } 1436 1437 if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) 1438 fatal("Failed to set uids to %u.", (u_int) pw->pw_uid); 1439 } 1440 1441 static void 1442 do_pwchange(Session *s) 1443 { 1444 fflush(NULL); 1445 fprintf(stderr, "WARNING: Your password has expired.\n"); 1446 if (s->ttyfd != -1) { 1447 fprintf(stderr, 1448 "You must change your password now and login again!\n"); 1449 #ifdef WITH_SELINUX 1450 setexeccon(NULL); 1451 #endif 1452 #ifdef PASSWD_NEEDS_USERNAME 1453 execl(_PATH_PASSWD_PROG, "passwd", s->pw->pw_name, 1454 (char *)NULL); 1455 #else 1456 execl(_PATH_PASSWD_PROG, "passwd", (char *)NULL); 1457 #endif 1458 perror("passwd"); 1459 } else { 1460 fprintf(stderr, 1461 "Password change required but no TTY available.\n"); 1462 } 1463 exit(1); 1464 } 1465 1466 static void 1467 child_close_fds(struct ssh *ssh) 1468 { 1469 extern int auth_sock; 1470 1471 if (auth_sock != -1) { 1472 close(auth_sock); 1473 auth_sock = -1; 1474 } 1475 1476 if (ssh_packet_get_connection_in(ssh) == 1477 ssh_packet_get_connection_out(ssh)) 1478 close(ssh_packet_get_connection_in(ssh)); 1479 else { 1480 close(ssh_packet_get_connection_in(ssh)); 1481 close(ssh_packet_get_connection_out(ssh)); 1482 } 1483 /* 1484 * Close all descriptors related to channels. They will still remain 1485 * open in the parent. 1486 */ 1487 /* XXX better use close-on-exec? -markus */ 1488 channel_close_all(ssh); 1489 1490 /* 1491 * Close any extra file descriptors. Note that there may still be 1492 * descriptors left by system functions. They will be closed later. 1493 */ 1494 endpwent(); 1495 1496 /* 1497 * Close any extra open file descriptors so that we don't have them 1498 * hanging around in clients. Note that we want to do this after 1499 * initgroups, because at least on Solaris 2.3 it leaves file 1500 * descriptors open. 1501 */ 1502 closefrom(STDERR_FILENO + 1); 1503 } 1504 1505 /* 1506 * Performs common processing for the child, such as setting up the 1507 * environment, closing extra file descriptors, setting the user and group 1508 * ids, and executing the command or shell. 1509 */ 1510 #define ARGV_MAX 10 1511 void 1512 do_child(struct ssh *ssh, Session *s, const char *command) 1513 { 1514 extern char **environ; 1515 char **env, *argv[ARGV_MAX], remote_id[512]; 1516 const char *shell, *shell0; 1517 struct passwd *pw = s->pw; 1518 int r = 0; 1519 1520 sshpkt_fmt_connection_id(ssh, remote_id, sizeof(remote_id)); 1521 1522 /* remove hostkey from the child's memory */ 1523 destroy_sensitive_data(); 1524 ssh_packet_clear_keys(ssh); 1525 1526 /* Force a password change */ 1527 if (s->authctxt->force_pwchange) { 1528 do_setusercontext(pw); 1529 child_close_fds(ssh); 1530 do_pwchange(s); 1531 exit(1); 1532 } 1533 1534 /* 1535 * Login(1) does this as well, and it needs uid 0 for the "-h" 1536 * switch, so we let login(1) to this for us. 1537 */ 1538 #ifdef HAVE_OSF_SIA 1539 session_setup_sia(pw, s->ttyfd == -1 ? NULL : s->tty); 1540 if (!check_quietlogin(s, command)) 1541 do_motd(); 1542 #else /* HAVE_OSF_SIA */ 1543 /* When PAM is enabled we rely on it to do the nologin check */ 1544 if (!options.use_pam) 1545 do_nologin(pw); 1546 do_setusercontext(pw); 1547 /* 1548 * PAM session modules in do_setusercontext may have 1549 * generated messages, so if this in an interactive 1550 * login then display them too. 1551 */ 1552 if (!check_quietlogin(s, command)) 1553 display_loginmsg(); 1554 #endif /* HAVE_OSF_SIA */ 1555 1556 #ifdef USE_PAM 1557 if (options.use_pam && !is_pam_session_open()) { 1558 debug3("PAM session not opened, exiting"); 1559 display_loginmsg(); 1560 exit(254); 1561 } 1562 #endif 1563 1564 /* 1565 * Get the shell from the password data. An empty shell field is 1566 * legal, and means /bin/sh. 1567 */ 1568 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; 1569 1570 /* 1571 * Make sure $SHELL points to the shell from the password file, 1572 * even if shell is overridden from login.conf 1573 */ 1574 env = do_setup_env(ssh, s, shell); 1575 1576 #ifdef HAVE_LOGIN_CAP 1577 shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell); 1578 #endif 1579 1580 /* 1581 * Close the connection descriptors; note that this is the child, and 1582 * the server will still have the socket open, and it is important 1583 * that we do not shutdown it. Note that the descriptors cannot be 1584 * closed before building the environment, as we call 1585 * ssh_remote_ipaddr there. 1586 */ 1587 child_close_fds(ssh); 1588 1589 /* 1590 * Must take new environment into use so that .ssh/rc, 1591 * /etc/ssh/sshrc and xauth are run in the proper environment. 1592 */ 1593 environ = env; 1594 1595 #if defined(KRB5) && defined(USE_AFS) 1596 /* 1597 * At this point, we check to see if AFS is active and if we have 1598 * a valid Kerberos 5 TGT. If so, it seems like a good idea to see 1599 * if we can (and need to) extend the ticket into an AFS token. If 1600 * we don't do this, we run into potential problems if the user's 1601 * home directory is in AFS and it's not world-readable. 1602 */ 1603 1604 if (options.kerberos_get_afs_token && k_hasafs() && 1605 (s->authctxt->krb5_ctx != NULL)) { 1606 char cell[64]; 1607 1608 debug("Getting AFS token"); 1609 1610 k_setpag(); 1611 1612 if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0) 1613 krb5_afslog(s->authctxt->krb5_ctx, 1614 s->authctxt->krb5_fwd_ccache, cell, NULL); 1615 1616 krb5_afslog_home(s->authctxt->krb5_ctx, 1617 s->authctxt->krb5_fwd_ccache, NULL, NULL, pw->pw_dir); 1618 } 1619 #endif 1620 1621 /* Change current directory to the user's home directory. */ 1622 if (chdir(pw->pw_dir) < 0) { 1623 /* Suppress missing homedir warning for chroot case */ 1624 #ifdef HAVE_LOGIN_CAP 1625 r = login_getcapbool(lc, "requirehome", 0); 1626 #endif 1627 if (r || !in_chroot) { 1628 fprintf(stderr, "Could not chdir to home " 1629 "directory %s: %s\n", pw->pw_dir, 1630 strerror(errno)); 1631 } 1632 if (r) 1633 exit(1); 1634 } 1635 1636 closefrom(STDERR_FILENO + 1); 1637 1638 do_rc_files(ssh, s, shell); 1639 1640 /* restore SIGPIPE for child */ 1641 signal(SIGPIPE, SIG_DFL); 1642 1643 if (s->is_subsystem == SUBSYSTEM_INT_SFTP_ERROR) { 1644 error("Connection from %s: refusing non-sftp session", 1645 remote_id); 1646 printf("This service allows sftp connections only.\n"); 1647 fflush(NULL); 1648 exit(1); 1649 } else if (s->is_subsystem == SUBSYSTEM_INT_SFTP) { 1650 extern int optind, optreset; 1651 int i; 1652 char *p, *args; 1653 1654 setproctitle("%s@%s", s->pw->pw_name, INTERNAL_SFTP_NAME); 1655 args = xstrdup(command ? command : "sftp-server"); 1656 for (i = 0, (p = strtok(args, " ")); p; (p = strtok(NULL, " "))) 1657 if (i < ARGV_MAX - 1) 1658 argv[i++] = p; 1659 argv[i] = NULL; 1660 optind = optreset = 1; 1661 __progname = argv[0]; 1662 #ifdef WITH_SELINUX 1663 ssh_selinux_change_context("sftpd_t"); 1664 #endif 1665 exit(sftp_server_main(i, argv, s->pw)); 1666 } 1667 1668 fflush(NULL); 1669 1670 /* Get the last component of the shell name. */ 1671 if ((shell0 = strrchr(shell, '/')) != NULL) 1672 shell0++; 1673 else 1674 shell0 = shell; 1675 1676 /* 1677 * If we have no command, execute the shell. In this case, the shell 1678 * name to be passed in argv[0] is preceded by '-' to indicate that 1679 * this is a login shell. 1680 */ 1681 if (!command) { 1682 char argv0[256]; 1683 1684 /* Start the shell. Set initial character to '-'. */ 1685 argv0[0] = '-'; 1686 1687 if (strlcpy(argv0 + 1, shell0, sizeof(argv0) - 1) 1688 >= sizeof(argv0) - 1) { 1689 errno = EINVAL; 1690 perror(shell); 1691 exit(1); 1692 } 1693 1694 /* Execute the shell. */ 1695 argv[0] = argv0; 1696 argv[1] = NULL; 1697 execve(shell, argv, env); 1698 1699 /* Executing the shell failed. */ 1700 perror(shell); 1701 exit(1); 1702 } 1703 /* 1704 * Execute the command using the user's shell. This uses the -c 1705 * option to execute the command. 1706 */ 1707 argv[0] = (char *) shell0; 1708 argv[1] = "-c"; 1709 argv[2] = (char *) command; 1710 argv[3] = NULL; 1711 execve(shell, argv, env); 1712 perror(shell); 1713 exit(1); 1714 } 1715 1716 void 1717 session_unused(int id) 1718 { 1719 debug3("%s: session id %d unused", __func__, id); 1720 if (id >= options.max_sessions || 1721 id >= sessions_nalloc) { 1722 fatal("%s: insane session id %d (max %d nalloc %d)", 1723 __func__, id, options.max_sessions, sessions_nalloc); 1724 } 1725 memset(&sessions[id], 0, sizeof(*sessions)); 1726 sessions[id].self = id; 1727 sessions[id].used = 0; 1728 sessions[id].chanid = -1; 1729 sessions[id].ptyfd = -1; 1730 sessions[id].ttyfd = -1; 1731 sessions[id].ptymaster = -1; 1732 sessions[id].x11_chanids = NULL; 1733 sessions[id].next_unused = sessions_first_unused; 1734 sessions_first_unused = id; 1735 } 1736 1737 Session * 1738 session_new(void) 1739 { 1740 Session *s, *tmp; 1741 1742 if (sessions_first_unused == -1) { 1743 if (sessions_nalloc >= options.max_sessions) 1744 return NULL; 1745 debug2("%s: allocate (allocated %d max %d)", 1746 __func__, sessions_nalloc, options.max_sessions); 1747 tmp = xrecallocarray(sessions, sessions_nalloc, 1748 sessions_nalloc + 1, sizeof(*sessions)); 1749 if (tmp == NULL) { 1750 error("%s: cannot allocate %d sessions", 1751 __func__, sessions_nalloc + 1); 1752 return NULL; 1753 } 1754 sessions = tmp; 1755 session_unused(sessions_nalloc++); 1756 } 1757 1758 if (sessions_first_unused >= sessions_nalloc || 1759 sessions_first_unused < 0) { 1760 fatal("%s: insane first_unused %d max %d nalloc %d", 1761 __func__, sessions_first_unused, options.max_sessions, 1762 sessions_nalloc); 1763 } 1764 1765 s = &sessions[sessions_first_unused]; 1766 if (s->used) { 1767 fatal("%s: session %d already used", 1768 __func__, sessions_first_unused); 1769 } 1770 sessions_first_unused = s->next_unused; 1771 s->used = 1; 1772 s->next_unused = -1; 1773 debug("session_new: session %d", s->self); 1774 1775 return s; 1776 } 1777 1778 static void 1779 session_dump(void) 1780 { 1781 int i; 1782 for (i = 0; i < sessions_nalloc; i++) { 1783 Session *s = &sessions[i]; 1784 1785 debug("dump: used %d next_unused %d session %d %p " 1786 "channel %d pid %ld", 1787 s->used, 1788 s->next_unused, 1789 s->self, 1790 s, 1791 s->chanid, 1792 (long)s->pid); 1793 } 1794 } 1795 1796 int 1797 session_open(Authctxt *authctxt, int chanid) 1798 { 1799 Session *s = session_new(); 1800 debug("session_open: channel %d", chanid); 1801 if (s == NULL) { 1802 error("no more sessions"); 1803 return 0; 1804 } 1805 s->authctxt = authctxt; 1806 s->pw = authctxt->pw; 1807 if (s->pw == NULL || !authctxt->valid) 1808 fatal("no user for session %d", s->self); 1809 debug("session_open: session %d: link with channel %d", s->self, chanid); 1810 s->chanid = chanid; 1811 return 1; 1812 } 1813 1814 Session * 1815 session_by_tty(char *tty) 1816 { 1817 int i; 1818 for (i = 0; i < sessions_nalloc; i++) { 1819 Session *s = &sessions[i]; 1820 if (s->used && s->ttyfd != -1 && strcmp(s->tty, tty) == 0) { 1821 debug("session_by_tty: session %d tty %s", i, tty); 1822 return s; 1823 } 1824 } 1825 debug("session_by_tty: unknown tty %.100s", tty); 1826 session_dump(); 1827 return NULL; 1828 } 1829 1830 static Session * 1831 session_by_channel(int id) 1832 { 1833 int i; 1834 for (i = 0; i < sessions_nalloc; i++) { 1835 Session *s = &sessions[i]; 1836 if (s->used && s->chanid == id) { 1837 debug("session_by_channel: session %d channel %d", 1838 i, id); 1839 return s; 1840 } 1841 } 1842 debug("session_by_channel: unknown channel %d", id); 1843 session_dump(); 1844 return NULL; 1845 } 1846 1847 static Session * 1848 session_by_x11_channel(int id) 1849 { 1850 int i, j; 1851 1852 for (i = 0; i < sessions_nalloc; i++) { 1853 Session *s = &sessions[i]; 1854 1855 if (s->x11_chanids == NULL || !s->used) 1856 continue; 1857 for (j = 0; s->x11_chanids[j] != -1; j++) { 1858 if (s->x11_chanids[j] == id) { 1859 debug("session_by_x11_channel: session %d " 1860 "channel %d", s->self, id); 1861 return s; 1862 } 1863 } 1864 } 1865 debug("session_by_x11_channel: unknown channel %d", id); 1866 session_dump(); 1867 return NULL; 1868 } 1869 1870 static Session * 1871 session_by_pid(pid_t pid) 1872 { 1873 int i; 1874 debug("session_by_pid: pid %ld", (long)pid); 1875 for (i = 0; i < sessions_nalloc; i++) { 1876 Session *s = &sessions[i]; 1877 if (s->used && s->pid == pid) 1878 return s; 1879 } 1880 error("session_by_pid: unknown pid %ld", (long)pid); 1881 session_dump(); 1882 return NULL; 1883 } 1884 1885 static int 1886 session_window_change_req(struct ssh *ssh, Session *s) 1887 { 1888 int r; 1889 1890 if ((r = sshpkt_get_u32(ssh, &s->col)) != 0 || 1891 (r = sshpkt_get_u32(ssh, &s->row)) != 0 || 1892 (r = sshpkt_get_u32(ssh, &s->xpixel)) != 0 || 1893 (r = sshpkt_get_u32(ssh, &s->ypixel)) != 0 || 1894 (r = sshpkt_get_end(ssh)) != 0) 1895 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 1896 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 1897 return 1; 1898 } 1899 1900 static int 1901 session_pty_req(struct ssh *ssh, Session *s) 1902 { 1903 int r; 1904 1905 if (!auth_opts->permit_pty_flag || !options.permit_tty) { 1906 debug("Allocating a pty not permitted for this connection."); 1907 return 0; 1908 } 1909 if (s->ttyfd != -1) { 1910 ssh_packet_disconnect(ssh, "Protocol error: you already have a pty."); 1911 return 0; 1912 } 1913 1914 if ((r = sshpkt_get_cstring(ssh, &s->term, NULL)) != 0 || 1915 (r = sshpkt_get_u32(ssh, &s->col)) != 0 || 1916 (r = sshpkt_get_u32(ssh, &s->row)) != 0 || 1917 (r = sshpkt_get_u32(ssh, &s->xpixel)) != 0 || 1918 (r = sshpkt_get_u32(ssh, &s->ypixel)) != 0) 1919 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 1920 1921 if (strcmp(s->term, "") == 0) { 1922 free(s->term); 1923 s->term = NULL; 1924 } 1925 1926 /* Allocate a pty and open it. */ 1927 debug("Allocating pty."); 1928 if (!PRIVSEP(pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, 1929 sizeof(s->tty)))) { 1930 free(s->term); 1931 s->term = NULL; 1932 s->ptyfd = -1; 1933 s->ttyfd = -1; 1934 error("session_pty_req: session %d alloc failed", s->self); 1935 return 0; 1936 } 1937 debug("session_pty_req: session %d alloc %s", s->self, s->tty); 1938 1939 ssh_tty_parse_modes(ssh, s->ttyfd); 1940 1941 if ((r = sshpkt_get_end(ssh)) != 0) 1942 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 1943 1944 if (!use_privsep) 1945 pty_setowner(s->pw, s->tty); 1946 1947 /* Set window size from the packet. */ 1948 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 1949 1950 session_proctitle(s); 1951 return 1; 1952 } 1953 1954 static int 1955 session_subsystem_req(struct ssh *ssh, Session *s) 1956 { 1957 struct stat st; 1958 int r, success = 0; 1959 char *prog, *cmd; 1960 u_int i; 1961 1962 if ((r = sshpkt_get_cstring(ssh, &s->subsys, NULL)) != 0 || 1963 (r = sshpkt_get_end(ssh)) != 0) 1964 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 1965 debug2("subsystem request for %.100s by user %s", s->subsys, 1966 s->pw->pw_name); 1967 1968 for (i = 0; i < options.num_subsystems; i++) { 1969 if (strcmp(s->subsys, options.subsystem_name[i]) == 0) { 1970 prog = options.subsystem_command[i]; 1971 cmd = options.subsystem_args[i]; 1972 if (strcmp(INTERNAL_SFTP_NAME, prog) == 0) { 1973 s->is_subsystem = SUBSYSTEM_INT_SFTP; 1974 debug("subsystem: %s", prog); 1975 } else { 1976 if (stat(prog, &st) < 0) 1977 debug("subsystem: cannot stat %s: %s", 1978 prog, strerror(errno)); 1979 s->is_subsystem = SUBSYSTEM_EXT; 1980 debug("subsystem: exec() %s", cmd); 1981 } 1982 success = do_exec(ssh, s, cmd) == 0; 1983 break; 1984 } 1985 } 1986 1987 if (!success) 1988 logit("subsystem request for %.100s by user %s failed, " 1989 "subsystem not found", s->subsys, s->pw->pw_name); 1990 1991 return success; 1992 } 1993 1994 static int 1995 session_x11_req(struct ssh *ssh, Session *s) 1996 { 1997 int r, success; 1998 u_char single_connection = 0; 1999 2000 if (s->auth_proto != NULL || s->auth_data != NULL) { 2001 error("session_x11_req: session %d: " 2002 "x11 forwarding already active", s->self); 2003 return 0; 2004 } 2005 if ((r = sshpkt_get_u8(ssh, &single_connection)) != 0 || 2006 (r = sshpkt_get_cstring(ssh, &s->auth_proto, NULL)) != 0 || 2007 (r = sshpkt_get_cstring(ssh, &s->auth_data, NULL)) != 0 || 2008 (r = sshpkt_get_u32(ssh, &s->screen)) != 0 || 2009 (r = sshpkt_get_end(ssh)) != 0) 2010 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 2011 2012 s->single_connection = single_connection; 2013 2014 if (xauth_valid_string(s->auth_proto) && 2015 xauth_valid_string(s->auth_data)) 2016 success = session_setup_x11fwd(ssh, s); 2017 else { 2018 success = 0; 2019 error("Invalid X11 forwarding data"); 2020 } 2021 if (!success) { 2022 free(s->auth_proto); 2023 free(s->auth_data); 2024 s->auth_proto = NULL; 2025 s->auth_data = NULL; 2026 } 2027 return success; 2028 } 2029 2030 static int 2031 session_shell_req(struct ssh *ssh, Session *s) 2032 { 2033 int r; 2034 2035 if ((r = sshpkt_get_end(ssh)) != 0) 2036 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 2037 return do_exec(ssh, s, NULL) == 0; 2038 } 2039 2040 static int 2041 session_exec_req(struct ssh *ssh, Session *s) 2042 { 2043 u_int success; 2044 int r; 2045 char *command = NULL; 2046 2047 if ((r = sshpkt_get_cstring(ssh, &command, NULL)) != 0 || 2048 (r = sshpkt_get_end(ssh)) != 0) 2049 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 2050 2051 success = do_exec(ssh, s, command) == 0; 2052 free(command); 2053 return success; 2054 } 2055 2056 static int 2057 session_break_req(struct ssh *ssh, Session *s) 2058 { 2059 int r; 2060 2061 if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* ignore */ 2062 (r = sshpkt_get_end(ssh)) != 0) 2063 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 2064 2065 if (s->ptymaster == -1 || tcsendbreak(s->ptymaster, 0) < 0) 2066 return 0; 2067 return 1; 2068 } 2069 2070 static int 2071 session_env_req(struct ssh *ssh, Session *s) 2072 { 2073 char *name, *val; 2074 u_int i; 2075 int r; 2076 2077 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 || 2078 (r = sshpkt_get_cstring(ssh, &val, NULL)) != 0 || 2079 (r = sshpkt_get_end(ssh)) != 0) 2080 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 2081 2082 /* Don't set too many environment variables */ 2083 if (s->num_env > 128) { 2084 debug2("Ignoring env request %s: too many env vars", name); 2085 goto fail; 2086 } 2087 2088 for (i = 0; i < options.num_accept_env; i++) { 2089 if (match_pattern(name, options.accept_env[i])) { 2090 debug2("Setting env %d: %s=%s", s->num_env, name, val); 2091 s->env = xrecallocarray(s->env, s->num_env, 2092 s->num_env + 1, sizeof(*s->env)); 2093 s->env[s->num_env].name = name; 2094 s->env[s->num_env].val = val; 2095 s->num_env++; 2096 return (1); 2097 } 2098 } 2099 debug2("Ignoring env request %s: disallowed name", name); 2100 2101 fail: 2102 free(name); 2103 free(val); 2104 return (0); 2105 } 2106 2107 /* 2108 * Conversion of signals from ssh channel request names. 2109 * Subset of signals from RFC 4254 section 6.10C, with SIGINFO as 2110 * local extension. 2111 */ 2112 static int 2113 name2sig(char *name) 2114 { 2115 #define SSH_SIG(x) if (strcmp(name, #x) == 0) return SIG ## x 2116 SSH_SIG(HUP); 2117 SSH_SIG(INT); 2118 SSH_SIG(KILL); 2119 SSH_SIG(QUIT); 2120 SSH_SIG(TERM); 2121 SSH_SIG(USR1); 2122 SSH_SIG(USR2); 2123 #undef SSH_SIG 2124 #ifdef SIGINFO 2125 if (strcmp(name, "INFO@openssh.com") == 0) 2126 return SIGINFO; 2127 #endif 2128 return -1; 2129 } 2130 2131 static int 2132 session_signal_req(struct ssh *ssh, Session *s) 2133 { 2134 char *signame = NULL; 2135 int r, sig, success = 0; 2136 2137 if ((r = sshpkt_get_cstring(ssh, &signame, NULL)) != 0 || 2138 (r = sshpkt_get_end(ssh)) != 0) { 2139 error("%s: parse packet: %s", __func__, ssh_err(r)); 2140 goto out; 2141 } 2142 if ((sig = name2sig(signame)) == -1) { 2143 error("%s: unsupported signal \"%s\"", __func__, signame); 2144 goto out; 2145 } 2146 if (s->pid <= 0) { 2147 error("%s: no pid for session %d", __func__, s->self); 2148 goto out; 2149 } 2150 if (s->forced || s->is_subsystem) { 2151 error("%s: refusing to send signal %s to %s session", __func__, 2152 signame, s->forced ? "forced-command" : "subsystem"); 2153 goto out; 2154 } 2155 if (!use_privsep || mm_is_monitor()) { 2156 error("%s: session signalling requires privilege separation", 2157 __func__); 2158 goto out; 2159 } 2160 2161 debug("%s: signal %s, killpg(%ld, %d)", __func__, signame, 2162 (long)s->pid, sig); 2163 temporarily_use_uid(s->pw); 2164 r = killpg(s->pid, sig); 2165 restore_uid(); 2166 if (r != 0) { 2167 error("%s: killpg(%ld, %d): %s", __func__, (long)s->pid, 2168 sig, strerror(errno)); 2169 goto out; 2170 } 2171 2172 /* success */ 2173 success = 1; 2174 out: 2175 free(signame); 2176 return success; 2177 } 2178 2179 static int 2180 session_auth_agent_req(struct ssh *ssh, Session *s) 2181 { 2182 static int called = 0; 2183 int r; 2184 2185 if ((r = sshpkt_get_end(ssh)) != 0) 2186 sshpkt_fatal(ssh, r, "%s: parse packet", __func__); 2187 if (!auth_opts->permit_agent_forwarding_flag || 2188 !options.allow_agent_forwarding) { 2189 debug("%s: agent forwarding disabled", __func__); 2190 return 0; 2191 } 2192 if (called) { 2193 return 0; 2194 } else { 2195 called = 1; 2196 return auth_input_request_forwarding(ssh, s->pw); 2197 } 2198 } 2199 2200 int 2201 session_input_channel_req(struct ssh *ssh, Channel *c, const char *rtype) 2202 { 2203 int success = 0; 2204 Session *s; 2205 2206 if ((s = session_by_channel(c->self)) == NULL) { 2207 logit("%s: no session %d req %.100s", __func__, c->self, rtype); 2208 return 0; 2209 } 2210 debug("%s: session %d req %s", __func__, s->self, rtype); 2211 2212 /* 2213 * a session is in LARVAL state until a shell, a command 2214 * or a subsystem is executed 2215 */ 2216 if (c->type == SSH_CHANNEL_LARVAL) { 2217 if (strcmp(rtype, "shell") == 0) { 2218 success = session_shell_req(ssh, s); 2219 } else if (strcmp(rtype, "exec") == 0) { 2220 success = session_exec_req(ssh, s); 2221 } else if (strcmp(rtype, "pty-req") == 0) { 2222 success = session_pty_req(ssh, s); 2223 } else if (strcmp(rtype, "x11-req") == 0) { 2224 success = session_x11_req(ssh, s); 2225 } else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) { 2226 success = session_auth_agent_req(ssh, s); 2227 } else if (strcmp(rtype, "subsystem") == 0) { 2228 success = session_subsystem_req(ssh, s); 2229 } else if (strcmp(rtype, "env") == 0) { 2230 success = session_env_req(ssh, s); 2231 } 2232 } 2233 if (strcmp(rtype, "window-change") == 0) { 2234 success = session_window_change_req(ssh, s); 2235 } else if (strcmp(rtype, "break") == 0) { 2236 success = session_break_req(ssh, s); 2237 } else if (strcmp(rtype, "signal") == 0) { 2238 success = session_signal_req(ssh, s); 2239 } 2240 2241 return success; 2242 } 2243 2244 void 2245 session_set_fds(struct ssh *ssh, Session *s, 2246 int fdin, int fdout, int fderr, int ignore_fderr, int is_tty) 2247 { 2248 /* 2249 * now that have a child and a pipe to the child, 2250 * we can activate our channel and register the fd's 2251 */ 2252 if (s->chanid == -1) 2253 fatal("no channel for session %d", s->self); 2254 channel_set_fds(ssh, s->chanid, 2255 fdout, fdin, fderr, 2256 ignore_fderr ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ, 2257 1, is_tty, CHAN_SES_WINDOW_DEFAULT); 2258 } 2259 2260 /* 2261 * Function to perform pty cleanup. Also called if we get aborted abnormally 2262 * (e.g., due to a dropped connection). 2263 */ 2264 void 2265 session_pty_cleanup2(Session *s) 2266 { 2267 if (s == NULL) { 2268 error("%s: no session", __func__); 2269 return; 2270 } 2271 if (s->ttyfd == -1) 2272 return; 2273 2274 debug("%s: session %d release %s", __func__, s->self, s->tty); 2275 2276 /* Record that the user has logged out. */ 2277 if (s->pid != 0) 2278 record_logout(s->pid, s->tty, s->pw->pw_name); 2279 2280 /* Release the pseudo-tty. */ 2281 if (getuid() == 0) 2282 pty_release(s->tty); 2283 2284 /* 2285 * Close the server side of the socket pairs. We must do this after 2286 * the pty cleanup, so that another process doesn't get this pty 2287 * while we're still cleaning up. 2288 */ 2289 if (s->ptymaster != -1 && close(s->ptymaster) < 0) 2290 error("close(s->ptymaster/%d): %s", 2291 s->ptymaster, strerror(errno)); 2292 2293 /* unlink pty from session */ 2294 s->ttyfd = -1; 2295 } 2296 2297 void 2298 session_pty_cleanup(Session *s) 2299 { 2300 PRIVSEP(session_pty_cleanup2(s)); 2301 } 2302 2303 static char * 2304 sig2name(int sig) 2305 { 2306 #define SSH_SIG(x) if (sig == SIG ## x) return #x 2307 SSH_SIG(ABRT); 2308 SSH_SIG(ALRM); 2309 SSH_SIG(FPE); 2310 SSH_SIG(HUP); 2311 SSH_SIG(ILL); 2312 SSH_SIG(INT); 2313 SSH_SIG(KILL); 2314 SSH_SIG(PIPE); 2315 SSH_SIG(QUIT); 2316 SSH_SIG(SEGV); 2317 SSH_SIG(TERM); 2318 SSH_SIG(USR1); 2319 SSH_SIG(USR2); 2320 #undef SSH_SIG 2321 return "SIG@openssh.com"; 2322 } 2323 2324 static void 2325 session_close_x11(struct ssh *ssh, int id) 2326 { 2327 Channel *c; 2328 2329 if ((c = channel_by_id(ssh, id)) == NULL) { 2330 debug("%s: x11 channel %d missing", __func__, id); 2331 } else { 2332 /* Detach X11 listener */ 2333 debug("%s: detach x11 channel %d", __func__, id); 2334 channel_cancel_cleanup(ssh, id); 2335 if (c->ostate != CHAN_OUTPUT_CLOSED) 2336 chan_mark_dead(ssh, c); 2337 } 2338 } 2339 2340 static void 2341 session_close_single_x11(struct ssh *ssh, int id, void *arg) 2342 { 2343 Session *s; 2344 u_int i; 2345 2346 debug3("%s: channel %d", __func__, id); 2347 channel_cancel_cleanup(ssh, id); 2348 if ((s = session_by_x11_channel(id)) == NULL) 2349 fatal("%s: no x11 channel %d", __func__, id); 2350 for (i = 0; s->x11_chanids[i] != -1; i++) { 2351 debug("%s: session %d: closing channel %d", 2352 __func__, s->self, s->x11_chanids[i]); 2353 /* 2354 * The channel "id" is already closing, but make sure we 2355 * close all of its siblings. 2356 */ 2357 if (s->x11_chanids[i] != id) 2358 session_close_x11(ssh, s->x11_chanids[i]); 2359 } 2360 free(s->x11_chanids); 2361 s->x11_chanids = NULL; 2362 free(s->display); 2363 s->display = NULL; 2364 free(s->auth_proto); 2365 s->auth_proto = NULL; 2366 free(s->auth_data); 2367 s->auth_data = NULL; 2368 free(s->auth_display); 2369 s->auth_display = NULL; 2370 } 2371 2372 static void 2373 session_exit_message(struct ssh *ssh, Session *s, int status) 2374 { 2375 Channel *c; 2376 int r; 2377 2378 if ((c = channel_lookup(ssh, s->chanid)) == NULL) 2379 fatal("%s: session %d: no channel %d", 2380 __func__, s->self, s->chanid); 2381 debug("%s: session %d channel %d pid %ld", 2382 __func__, s->self, s->chanid, (long)s->pid); 2383 2384 if (WIFEXITED(status)) { 2385 channel_request_start(ssh, s->chanid, "exit-status", 0); 2386 if ((r = sshpkt_put_u32(ssh, WEXITSTATUS(status))) != 0 || 2387 (r = sshpkt_send(ssh)) != 0) 2388 sshpkt_fatal(ssh, r, "%s: exit reply", __func__); 2389 } else if (WIFSIGNALED(status)) { 2390 channel_request_start(ssh, s->chanid, "exit-signal", 0); 2391 #ifndef WCOREDUMP 2392 # define WCOREDUMP(x) (0) 2393 #endif 2394 if ((r = sshpkt_put_cstring(ssh, sig2name(WTERMSIG(status)))) != 0 || 2395 (r = sshpkt_put_u8(ssh, WCOREDUMP(status)? 1 : 0)) != 0 || 2396 (r = sshpkt_put_cstring(ssh, "")) != 0 || 2397 (r = sshpkt_put_cstring(ssh, "")) != 0 || 2398 (r = sshpkt_send(ssh)) != 0) 2399 sshpkt_fatal(ssh, r, "%s: exit reply", __func__); 2400 } else { 2401 /* Some weird exit cause. Just exit. */ 2402 ssh_packet_disconnect(ssh, "wait returned status %04x.", status); 2403 } 2404 2405 /* disconnect channel */ 2406 debug("%s: release channel %d", __func__, s->chanid); 2407 2408 /* 2409 * Adjust cleanup callback attachment to send close messages when 2410 * the channel gets EOF. The session will be then be closed 2411 * by session_close_by_channel when the childs close their fds. 2412 */ 2413 channel_register_cleanup(ssh, c->self, session_close_by_channel, 1); 2414 2415 /* 2416 * emulate a write failure with 'chan_write_failed', nobody will be 2417 * interested in data we write. 2418 * Note that we must not call 'chan_read_failed', since there could 2419 * be some more data waiting in the pipe. 2420 */ 2421 if (c->ostate != CHAN_OUTPUT_CLOSED) 2422 chan_write_failed(ssh, c); 2423 } 2424 2425 void 2426 session_close(struct ssh *ssh, Session *s) 2427 { 2428 u_int i; 2429 2430 verbose("Close session: user %s from %.200s port %d id %d", 2431 s->pw->pw_name, 2432 ssh_remote_ipaddr(ssh), 2433 ssh_remote_port(ssh), 2434 s->self); 2435 2436 if (s->ttyfd != -1) 2437 session_pty_cleanup(s); 2438 free(s->term); 2439 free(s->display); 2440 free(s->x11_chanids); 2441 free(s->auth_display); 2442 free(s->auth_data); 2443 free(s->auth_proto); 2444 free(s->subsys); 2445 if (s->env != NULL) { 2446 for (i = 0; i < s->num_env; i++) { 2447 free(s->env[i].name); 2448 free(s->env[i].val); 2449 } 2450 free(s->env); 2451 } 2452 session_proctitle(s); 2453 session_unused(s->self); 2454 } 2455 2456 void 2457 session_close_by_pid(struct ssh *ssh, pid_t pid, int status) 2458 { 2459 Session *s = session_by_pid(pid); 2460 if (s == NULL) { 2461 debug("%s: no session for pid %ld", __func__, (long)pid); 2462 return; 2463 } 2464 if (s->chanid != -1) 2465 session_exit_message(ssh, s, status); 2466 if (s->ttyfd != -1) 2467 session_pty_cleanup(s); 2468 s->pid = 0; 2469 } 2470 2471 /* 2472 * this is called when a channel dies before 2473 * the session 'child' itself dies 2474 */ 2475 void 2476 session_close_by_channel(struct ssh *ssh, int id, void *arg) 2477 { 2478 Session *s = session_by_channel(id); 2479 u_int i; 2480 2481 if (s == NULL) { 2482 debug("%s: no session for id %d", __func__, id); 2483 return; 2484 } 2485 debug("%s: channel %d child %ld", __func__, id, (long)s->pid); 2486 if (s->pid != 0) { 2487 debug("%s: channel %d: has child, ttyfd %d", 2488 __func__, id, s->ttyfd); 2489 /* 2490 * delay detach of session, but release pty, since 2491 * the fd's to the child are already closed 2492 */ 2493 if (s->ttyfd != -1) 2494 session_pty_cleanup(s); 2495 return; 2496 } 2497 /* detach by removing callback */ 2498 channel_cancel_cleanup(ssh, s->chanid); 2499 2500 /* Close any X11 listeners associated with this session */ 2501 if (s->x11_chanids != NULL) { 2502 for (i = 0; s->x11_chanids[i] != -1; i++) { 2503 session_close_x11(ssh, s->x11_chanids[i]); 2504 s->x11_chanids[i] = -1; 2505 } 2506 } 2507 2508 s->chanid = -1; 2509 session_close(ssh, s); 2510 } 2511 2512 void 2513 session_destroy_all(struct ssh *ssh, void (*closefunc)(Session *)) 2514 { 2515 int i; 2516 for (i = 0; i < sessions_nalloc; i++) { 2517 Session *s = &sessions[i]; 2518 if (s->used) { 2519 if (closefunc != NULL) 2520 closefunc(s); 2521 else 2522 session_close(ssh, s); 2523 } 2524 } 2525 } 2526 2527 static char * 2528 session_tty_list(void) 2529 { 2530 static char buf[1024]; 2531 int i; 2532 char *cp; 2533 2534 buf[0] = '\0'; 2535 for (i = 0; i < sessions_nalloc; i++) { 2536 Session *s = &sessions[i]; 2537 if (s->used && s->ttyfd != -1) { 2538 2539 if (strncmp(s->tty, "/dev/", 5) != 0) { 2540 cp = strrchr(s->tty, '/'); 2541 cp = (cp == NULL) ? s->tty : cp + 1; 2542 } else 2543 cp = s->tty + 5; 2544 2545 if (buf[0] != '\0') 2546 strlcat(buf, ",", sizeof buf); 2547 strlcat(buf, cp, sizeof buf); 2548 } 2549 } 2550 if (buf[0] == '\0') 2551 strlcpy(buf, "notty", sizeof buf); 2552 return buf; 2553 } 2554 2555 void 2556 session_proctitle(Session *s) 2557 { 2558 if (s->pw == NULL) 2559 error("no user for session %d", s->self); 2560 else 2561 setproctitle("%s@%s", s->pw->pw_name, session_tty_list()); 2562 } 2563 2564 int 2565 session_setup_x11fwd(struct ssh *ssh, Session *s) 2566 { 2567 struct stat st; 2568 char display[512], auth_display[512]; 2569 char hostname[NI_MAXHOST]; 2570 u_int i; 2571 2572 if (!auth_opts->permit_x11_forwarding_flag) { 2573 ssh_packet_send_debug(ssh, "X11 forwarding disabled by key options."); 2574 return 0; 2575 } 2576 if (!options.x11_forwarding) { 2577 debug("X11 forwarding disabled in server configuration file."); 2578 return 0; 2579 } 2580 if (options.xauth_location == NULL || 2581 (stat(options.xauth_location, &st) == -1)) { 2582 ssh_packet_send_debug(ssh, "No xauth program; cannot forward X11."); 2583 return 0; 2584 } 2585 if (s->display != NULL) { 2586 debug("X11 display already set."); 2587 return 0; 2588 } 2589 if (x11_create_display_inet(ssh, options.x11_display_offset, 2590 options.x11_use_localhost, s->single_connection, 2591 &s->display_number, &s->x11_chanids) == -1) { 2592 debug("x11_create_display_inet failed."); 2593 return 0; 2594 } 2595 for (i = 0; s->x11_chanids[i] != -1; i++) { 2596 channel_register_cleanup(ssh, s->x11_chanids[i], 2597 session_close_single_x11, 0); 2598 } 2599 2600 /* Set up a suitable value for the DISPLAY variable. */ 2601 if (gethostname(hostname, sizeof(hostname)) < 0) 2602 fatal("gethostname: %.100s", strerror(errno)); 2603 /* 2604 * auth_display must be used as the displayname when the 2605 * authorization entry is added with xauth(1). This will be 2606 * different than the DISPLAY string for localhost displays. 2607 */ 2608 if (options.x11_use_localhost) { 2609 snprintf(display, sizeof display, "localhost:%u.%u", 2610 s->display_number, s->screen); 2611 snprintf(auth_display, sizeof auth_display, "unix:%u.%u", 2612 s->display_number, s->screen); 2613 s->display = xstrdup(display); 2614 s->auth_display = xstrdup(auth_display); 2615 } else { 2616 #ifdef IPADDR_IN_DISPLAY 2617 struct hostent *he; 2618 struct in_addr my_addr; 2619 2620 he = gethostbyname(hostname); 2621 if (he == NULL) { 2622 error("Can't get IP address for X11 DISPLAY."); 2623 ssh_packet_send_debug(ssh, "Can't get IP address for X11 DISPLAY."); 2624 return 0; 2625 } 2626 memcpy(&my_addr, he->h_addr_list[0], sizeof(struct in_addr)); 2627 snprintf(display, sizeof display, "%.50s:%u.%u", inet_ntoa(my_addr), 2628 s->display_number, s->screen); 2629 #else 2630 snprintf(display, sizeof display, "%.400s:%u.%u", hostname, 2631 s->display_number, s->screen); 2632 #endif 2633 s->display = xstrdup(display); 2634 s->auth_display = xstrdup(display); 2635 } 2636 2637 return 1; 2638 } 2639 2640 static void 2641 do_authenticated2(struct ssh *ssh, Authctxt *authctxt) 2642 { 2643 server_loop2(ssh, authctxt); 2644 } 2645 2646 void 2647 do_cleanup(struct ssh *ssh, Authctxt *authctxt) 2648 { 2649 static int called = 0; 2650 2651 debug("do_cleanup"); 2652 2653 /* no cleanup if we're in the child for login shell */ 2654 if (is_child) 2655 return; 2656 2657 /* avoid double cleanup */ 2658 if (called) 2659 return; 2660 called = 1; 2661 2662 if (authctxt == NULL) 2663 return; 2664 2665 #ifdef USE_PAM 2666 if (options.use_pam) { 2667 sshpam_cleanup(); 2668 sshpam_thread_cleanup(); 2669 } 2670 #endif 2671 2672 if (!authctxt->authenticated) 2673 return; 2674 2675 #ifdef KRB5 2676 if (options.kerberos_ticket_cleanup && 2677 authctxt->krb5_ctx) 2678 krb5_cleanup_proc(authctxt); 2679 #endif 2680 2681 #ifdef GSSAPI 2682 if (options.gss_cleanup_creds) 2683 ssh_gssapi_cleanup_creds(); 2684 #endif 2685 2686 /* remove agent socket */ 2687 auth_sock_cleanup_proc(authctxt->pw); 2688 2689 /* remove userauth info */ 2690 if (auth_info_file != NULL) { 2691 temporarily_use_uid(authctxt->pw); 2692 unlink(auth_info_file); 2693 restore_uid(); 2694 free(auth_info_file); 2695 auth_info_file = NULL; 2696 } 2697 2698 /* 2699 * Cleanup ptys/utmp only if privsep is disabled, 2700 * or if running in monitor. 2701 */ 2702 if (!use_privsep || mm_is_monitor()) 2703 session_destroy_all(ssh, session_pty_cleanup2); 2704 } 2705 2706 /* Return a name for the remote host that fits inside utmp_size */ 2707 2708 const char * 2709 session_get_remote_name_or_ip(struct ssh *ssh, u_int utmp_size, int use_dns) 2710 { 2711 const char *remote = ""; 2712 2713 if (utmp_size > 0) 2714 remote = auth_get_canonical_hostname(ssh, use_dns); 2715 if (utmp_size == 0 || strlen(remote) > utmp_size) 2716 remote = ssh_remote_ipaddr(ssh); 2717 return remote; 2718 } 2719 2720