1 /* $OpenBSD: session.c,v 1.286 2016/11/30 03:00:05 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 <sys/types.h> 37 #include <sys/wait.h> 38 #include <sys/un.h> 39 #include <sys/stat.h> 40 #include <sys/socket.h> 41 #include <sys/queue.h> 42 43 #include <ctype.h> 44 #include <errno.h> 45 #include <fcntl.h> 46 #include <grp.h> 47 #include <login_cap.h> 48 #include <netdb.h> 49 #include <paths.h> 50 #include <pwd.h> 51 #include <signal.h> 52 #include <stdio.h> 53 #include <stdlib.h> 54 #include <string.h> 55 #include <unistd.h> 56 #include <limits.h> 57 58 #include "xmalloc.h" 59 #include "ssh.h" 60 #include "ssh2.h" 61 #include "sshpty.h" 62 #include "packet.h" 63 #include "buffer.h" 64 #include "match.h" 65 #include "uidswap.h" 66 #include "compat.h" 67 #include "channels.h" 68 #include "key.h" 69 #include "cipher.h" 70 #include "kex.h" 71 #include "hostfile.h" 72 #include "auth.h" 73 #include "auth-options.h" 74 #include "authfd.h" 75 #include "pathnames.h" 76 #include "log.h" 77 #include "misc.h" 78 #include "servconf.h" 79 #include "sshlogin.h" 80 #include "serverloop.h" 81 #include "canohost.h" 82 #include "session.h" 83 #ifdef GSSAPI 84 #include "ssh-gss.h" 85 #endif 86 #include "monitor_wrap.h" 87 #include "sftp.h" 88 89 #ifdef KRB5 90 #include <kafs.h> 91 #endif 92 93 #define IS_INTERNAL_SFTP(c) \ 94 (!strncmp(c, INTERNAL_SFTP_NAME, sizeof(INTERNAL_SFTP_NAME) - 1) && \ 95 (c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\0' || \ 96 c[sizeof(INTERNAL_SFTP_NAME) - 1] == ' ' || \ 97 c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\t')) 98 99 /* func */ 100 101 Session *session_new(void); 102 void session_set_fds(Session *, int, int, int, int, int); 103 void session_pty_cleanup(Session *); 104 void session_proctitle(Session *); 105 int session_setup_x11fwd(Session *); 106 int do_exec_pty(Session *, const char *); 107 int do_exec_no_pty(Session *, const char *); 108 int do_exec(Session *, const char *); 109 void do_login(Session *, const char *); 110 void do_child(Session *, const char *); 111 void do_motd(void); 112 int check_quietlogin(Session *, const char *); 113 114 static void do_authenticated2(Authctxt *); 115 116 static int session_pty_req(Session *); 117 118 /* import */ 119 extern ServerOptions options; 120 extern char *__progname; 121 extern int log_stderr; 122 extern int debug_flag; 123 extern u_int utmp_len; 124 extern int startup_pipe; 125 extern void destroy_sensitive_data(void); 126 extern Buffer loginmsg; 127 128 /* original command from peer. */ 129 const char *original_command = NULL; 130 131 /* data */ 132 static int sessions_first_unused = -1; 133 static int sessions_nalloc = 0; 134 static Session *sessions = NULL; 135 136 #define SUBSYSTEM_NONE 0 137 #define SUBSYSTEM_EXT 1 138 #define SUBSYSTEM_INT_SFTP 2 139 #define SUBSYSTEM_INT_SFTP_ERROR 3 140 141 login_cap_t *lc; 142 143 static int is_child = 0; 144 static int in_chroot = 0; 145 146 /* Name and directory of socket for authentication agent forwarding. */ 147 static char *auth_sock_name = NULL; 148 static char *auth_sock_dir = NULL; 149 150 /* removes the agent forwarding socket */ 151 152 static void 153 auth_sock_cleanup_proc(struct passwd *pw) 154 { 155 if (auth_sock_name != NULL) { 156 temporarily_use_uid(pw); 157 unlink(auth_sock_name); 158 rmdir(auth_sock_dir); 159 auth_sock_name = NULL; 160 restore_uid(); 161 } 162 } 163 164 static int 165 auth_input_request_forwarding(struct passwd * pw) 166 { 167 Channel *nc; 168 int sock = -1; 169 170 if (auth_sock_name != NULL) { 171 error("authentication forwarding requested twice."); 172 return 0; 173 } 174 175 /* Temporarily drop privileged uid for mkdir/bind. */ 176 temporarily_use_uid(pw); 177 178 /* Allocate a buffer for the socket name, and format the name. */ 179 auth_sock_dir = xstrdup("/tmp/ssh-XXXXXXXXXX"); 180 181 /* Create private directory for socket */ 182 if (mkdtemp(auth_sock_dir) == NULL) { 183 packet_send_debug("Agent forwarding disabled: " 184 "mkdtemp() failed: %.100s", strerror(errno)); 185 restore_uid(); 186 free(auth_sock_dir); 187 auth_sock_dir = NULL; 188 goto authsock_err; 189 } 190 191 xasprintf(&auth_sock_name, "%s/agent.%ld", 192 auth_sock_dir, (long) getpid()); 193 194 /* Start a Unix listener on auth_sock_name. */ 195 sock = unix_listener(auth_sock_name, SSH_LISTEN_BACKLOG, 0); 196 197 /* Restore the privileged uid. */ 198 restore_uid(); 199 200 /* Check for socket/bind/listen failure. */ 201 if (sock < 0) 202 goto authsock_err; 203 204 /* Allocate a channel for the authentication agent socket. */ 205 nc = channel_new("auth socket", 206 SSH_CHANNEL_AUTH_SOCKET, sock, sock, -1, 207 CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 208 0, "auth socket", 1); 209 nc->path = xstrdup(auth_sock_name); 210 return 1; 211 212 authsock_err: 213 free(auth_sock_name); 214 if (auth_sock_dir != NULL) { 215 rmdir(auth_sock_dir); 216 free(auth_sock_dir); 217 } 218 if (sock != -1) 219 close(sock); 220 auth_sock_name = NULL; 221 auth_sock_dir = NULL; 222 return 0; 223 } 224 225 static void 226 display_loginmsg(void) 227 { 228 if (buffer_len(&loginmsg) > 0) { 229 buffer_append(&loginmsg, "\0", 1); 230 printf("%s", (char *)buffer_ptr(&loginmsg)); 231 buffer_clear(&loginmsg); 232 } 233 } 234 235 void 236 do_authenticated(Authctxt *authctxt) 237 { 238 setproctitle("%s", authctxt->pw->pw_name); 239 240 /* setup the channel layer */ 241 /* XXX - streamlocal? */ 242 if (no_port_forwarding_flag || options.disable_forwarding || 243 (options.allow_tcp_forwarding & FORWARD_LOCAL) == 0) 244 channel_disable_adm_local_opens(); 245 else 246 channel_permit_all_opens(); 247 248 auth_debug_send(); 249 250 do_authenticated2(authctxt); 251 do_cleanup(authctxt); 252 } 253 254 /* Check untrusted xauth strings for metacharacters */ 255 static int 256 xauth_valid_string(const char *s) 257 { 258 size_t i; 259 260 for (i = 0; s[i] != '\0'; i++) { 261 if (!isalnum((u_char)s[i]) && 262 s[i] != '.' && s[i] != ':' && s[i] != '/' && 263 s[i] != '-' && s[i] != '_') 264 return 0; 265 } 266 return 1; 267 } 268 269 #define USE_PIPES 1 270 /* 271 * This is called to fork and execute a command when we have no tty. This 272 * will call do_child from the child, and server_loop from the parent after 273 * setting up file descriptors and such. 274 */ 275 int 276 do_exec_no_pty(Session *s, const char *command) 277 { 278 pid_t pid; 279 #ifdef USE_PIPES 280 int pin[2], pout[2], perr[2]; 281 282 if (s == NULL) 283 fatal("do_exec_no_pty: no session"); 284 285 /* Allocate pipes for communicating with the program. */ 286 if (pipe(pin) < 0) { 287 error("%s: pipe in: %.100s", __func__, strerror(errno)); 288 return -1; 289 } 290 if (pipe(pout) < 0) { 291 error("%s: pipe out: %.100s", __func__, strerror(errno)); 292 close(pin[0]); 293 close(pin[1]); 294 return -1; 295 } 296 if (pipe(perr) < 0) { 297 error("%s: pipe err: %.100s", __func__, 298 strerror(errno)); 299 close(pin[0]); 300 close(pin[1]); 301 close(pout[0]); 302 close(pout[1]); 303 return -1; 304 } 305 #else 306 int inout[2], err[2]; 307 308 if (s == NULL) 309 fatal("do_exec_no_pty: no session"); 310 311 /* Uses socket pairs to communicate with the program. */ 312 if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) < 0) { 313 error("%s: socketpair #1: %.100s", __func__, strerror(errno)); 314 return -1; 315 } 316 if (socketpair(AF_UNIX, SOCK_STREAM, 0, err) < 0) { 317 error("%s: socketpair #2: %.100s", __func__, 318 strerror(errno)); 319 close(inout[0]); 320 close(inout[1]); 321 return -1; 322 } 323 #endif 324 325 session_proctitle(s); 326 327 /* Fork the child. */ 328 switch ((pid = fork())) { 329 case -1: 330 error("%s: fork: %.100s", __func__, strerror(errno)); 331 #ifdef USE_PIPES 332 close(pin[0]); 333 close(pin[1]); 334 close(pout[0]); 335 close(pout[1]); 336 close(perr[0]); 337 close(perr[1]); 338 #else 339 close(inout[0]); 340 close(inout[1]); 341 close(err[0]); 342 close(err[1]); 343 #endif 344 return -1; 345 case 0: 346 is_child = 1; 347 348 /* Child. Reinitialize the log since the pid has changed. */ 349 log_init(__progname, options.log_level, 350 options.log_facility, log_stderr); 351 352 /* 353 * Create a new session and process group since the 4.4BSD 354 * setlogin() affects the entire process group. 355 */ 356 if (setsid() < 0) 357 error("setsid failed: %.100s", strerror(errno)); 358 359 #ifdef USE_PIPES 360 /* 361 * Redirect stdin. We close the parent side of the socket 362 * pair, and make the child side the standard input. 363 */ 364 close(pin[1]); 365 if (dup2(pin[0], 0) < 0) 366 perror("dup2 stdin"); 367 close(pin[0]); 368 369 /* Redirect stdout. */ 370 close(pout[0]); 371 if (dup2(pout[1], 1) < 0) 372 perror("dup2 stdout"); 373 close(pout[1]); 374 375 /* Redirect stderr. */ 376 close(perr[0]); 377 if (dup2(perr[1], 2) < 0) 378 perror("dup2 stderr"); 379 close(perr[1]); 380 #else 381 /* 382 * Redirect stdin, stdout, and stderr. Stdin and stdout will 383 * use the same socket, as some programs (particularly rdist) 384 * seem to depend on it. 385 */ 386 close(inout[1]); 387 close(err[1]); 388 if (dup2(inout[0], 0) < 0) /* stdin */ 389 perror("dup2 stdin"); 390 if (dup2(inout[0], 1) < 0) /* stdout (same as stdin) */ 391 perror("dup2 stdout"); 392 close(inout[0]); 393 if (dup2(err[0], 2) < 0) /* stderr */ 394 perror("dup2 stderr"); 395 close(err[0]); 396 #endif 397 398 /* Do processing for the child (exec command etc). */ 399 do_child(s, command); 400 /* NOTREACHED */ 401 default: 402 break; 403 } 404 405 s->pid = pid; 406 /* Set interactive/non-interactive mode. */ 407 packet_set_interactive(s->display != NULL, 408 options.ip_qos_interactive, options.ip_qos_bulk); 409 410 #ifdef USE_PIPES 411 /* We are the parent. Close the child sides of the pipes. */ 412 close(pin[0]); 413 close(pout[1]); 414 close(perr[1]); 415 416 session_set_fds(s, pin[1], pout[0], perr[0], 417 s->is_subsystem, 0); 418 #else 419 /* We are the parent. Close the child sides of the socket pairs. */ 420 close(inout[0]); 421 close(err[0]); 422 423 /* 424 * Enter the interactive session. Note: server_loop must be able to 425 * handle the case that fdin and fdout are the same. 426 */ 427 session_set_fds(s, inout[1], inout[1], err[1], 428 s->is_subsystem, 0); 429 #endif 430 return 0; 431 } 432 433 /* 434 * This is called to fork and execute a command when we have a tty. This 435 * will call do_child from the child, and server_loop from the parent after 436 * setting up file descriptors, controlling tty, updating wtmp, utmp, 437 * lastlog, and other such operations. 438 */ 439 int 440 do_exec_pty(Session *s, const char *command) 441 { 442 int fdout, ptyfd, ttyfd, ptymaster; 443 pid_t pid; 444 445 if (s == NULL) 446 fatal("do_exec_pty: no session"); 447 ptyfd = s->ptyfd; 448 ttyfd = s->ttyfd; 449 450 /* 451 * Create another descriptor of the pty master side for use as the 452 * standard input. We could use the original descriptor, but this 453 * simplifies code in server_loop. The descriptor is bidirectional. 454 * Do this before forking (and cleanup in the child) so as to 455 * detect and gracefully fail out-of-fd conditions. 456 */ 457 if ((fdout = dup(ptyfd)) < 0) { 458 error("%s: dup #1: %s", __func__, strerror(errno)); 459 close(ttyfd); 460 close(ptyfd); 461 return -1; 462 } 463 /* we keep a reference to the pty master */ 464 if ((ptymaster = dup(ptyfd)) < 0) { 465 error("%s: dup #2: %s", __func__, strerror(errno)); 466 close(ttyfd); 467 close(ptyfd); 468 close(fdout); 469 return -1; 470 } 471 472 /* Fork the child. */ 473 switch ((pid = fork())) { 474 case -1: 475 error("%s: fork: %.100s", __func__, strerror(errno)); 476 close(fdout); 477 close(ptymaster); 478 close(ttyfd); 479 close(ptyfd); 480 return -1; 481 case 0: 482 is_child = 1; 483 484 close(fdout); 485 close(ptymaster); 486 487 /* Child. Reinitialize the log because the pid has changed. */ 488 log_init(__progname, options.log_level, 489 options.log_facility, log_stderr); 490 /* Close the master side of the pseudo tty. */ 491 close(ptyfd); 492 493 /* Make the pseudo tty our controlling tty. */ 494 pty_make_controlling_tty(&ttyfd, s->tty); 495 496 /* Redirect stdin/stdout/stderr from the pseudo tty. */ 497 if (dup2(ttyfd, 0) < 0) 498 error("dup2 stdin: %s", strerror(errno)); 499 if (dup2(ttyfd, 1) < 0) 500 error("dup2 stdout: %s", strerror(errno)); 501 if (dup2(ttyfd, 2) < 0) 502 error("dup2 stderr: %s", strerror(errno)); 503 504 /* Close the extra descriptor for the pseudo tty. */ 505 close(ttyfd); 506 507 /* record login, etc. similar to login(1) */ 508 do_login(s, command); 509 510 /* 511 * Do common processing for the child, such as execing 512 * the command. 513 */ 514 do_child(s, command); 515 /* NOTREACHED */ 516 default: 517 break; 518 } 519 s->pid = pid; 520 521 /* Parent. Close the slave side of the pseudo tty. */ 522 close(ttyfd); 523 524 /* Enter interactive session. */ 525 s->ptymaster = ptymaster; 526 packet_set_interactive(1, 527 options.ip_qos_interactive, options.ip_qos_bulk); 528 session_set_fds(s, ptyfd, fdout, -1, 1, 1); 529 return 0; 530 } 531 532 /* 533 * This is called to fork and execute a command. If another command is 534 * to be forced, execute that instead. 535 */ 536 int 537 do_exec(Session *s, const char *command) 538 { 539 struct ssh *ssh = active_state; /* XXX */ 540 int ret; 541 const char *forced = NULL, *tty = NULL; 542 char session_type[1024]; 543 544 if (options.adm_forced_command) { 545 original_command = command; 546 command = options.adm_forced_command; 547 forced = "(config)"; 548 } else if (forced_command) { 549 original_command = command; 550 command = forced_command; 551 forced = "(key-option)"; 552 } 553 if (forced != NULL) { 554 if (IS_INTERNAL_SFTP(command)) { 555 s->is_subsystem = s->is_subsystem ? 556 SUBSYSTEM_INT_SFTP : SUBSYSTEM_INT_SFTP_ERROR; 557 } else if (s->is_subsystem) 558 s->is_subsystem = SUBSYSTEM_EXT; 559 snprintf(session_type, sizeof(session_type), 560 "forced-command %s '%.900s'", forced, command); 561 } else if (s->is_subsystem) { 562 snprintf(session_type, sizeof(session_type), 563 "subsystem '%.900s'", s->subsys); 564 } else if (command == NULL) { 565 snprintf(session_type, sizeof(session_type), "shell"); 566 } else { 567 /* NB. we don't log unforced commands to preserve privacy */ 568 snprintf(session_type, sizeof(session_type), "command"); 569 } 570 571 if (s->ttyfd != -1) { 572 tty = s->tty; 573 if (strncmp(tty, "/dev/", 5) == 0) 574 tty += 5; 575 } 576 577 verbose("Starting session: %s%s%s for %s from %.200s port %d id %d", 578 session_type, 579 tty == NULL ? "" : " on ", 580 tty == NULL ? "" : tty, 581 s->pw->pw_name, 582 ssh_remote_ipaddr(ssh), 583 ssh_remote_port(ssh), 584 s->self); 585 586 #ifdef GSSAPI 587 if (options.gss_authentication) { 588 temporarily_use_uid(s->pw); 589 ssh_gssapi_storecreds(); 590 restore_uid(); 591 } 592 #endif 593 if (s->ttyfd != -1) 594 ret = do_exec_pty(s, command); 595 else 596 ret = do_exec_no_pty(s, command); 597 598 original_command = NULL; 599 600 /* 601 * Clear loginmsg: it's the child's responsibility to display 602 * it to the user, otherwise multiple sessions may accumulate 603 * multiple copies of the login messages. 604 */ 605 buffer_clear(&loginmsg); 606 607 return ret; 608 } 609 610 611 /* administrative, login(1)-like work */ 612 void 613 do_login(Session *s, const char *command) 614 { 615 struct ssh *ssh = active_state; /* XXX */ 616 socklen_t fromlen; 617 struct sockaddr_storage from; 618 struct passwd * pw = s->pw; 619 pid_t pid = getpid(); 620 621 /* 622 * Get IP address of client. If the connection is not a socket, let 623 * the address be 0.0.0.0. 624 */ 625 memset(&from, 0, sizeof(from)); 626 fromlen = sizeof(from); 627 if (packet_connection_is_on_socket()) { 628 if (getpeername(packet_get_connection_in(), 629 (struct sockaddr *)&from, &fromlen) < 0) { 630 debug("getpeername: %.100s", strerror(errno)); 631 cleanup_exit(255); 632 } 633 } 634 635 /* Record that there was a login on that tty from the remote host. */ 636 if (!use_privsep) 637 record_login(pid, s->tty, pw->pw_name, pw->pw_uid, 638 session_get_remote_name_or_ip(ssh, utmp_len, 639 options.use_dns), 640 (struct sockaddr *)&from, fromlen); 641 642 if (check_quietlogin(s, command)) 643 return; 644 645 display_loginmsg(); 646 647 do_motd(); 648 } 649 650 /* 651 * Display the message of the day. 652 */ 653 void 654 do_motd(void) 655 { 656 FILE *f; 657 char buf[256]; 658 659 if (options.print_motd) { 660 f = fopen(login_getcapstr(lc, "welcome", "/etc/motd", 661 "/etc/motd"), "r"); 662 if (f) { 663 while (fgets(buf, sizeof(buf), f)) 664 fputs(buf, stdout); 665 fclose(f); 666 } 667 } 668 } 669 670 671 /* 672 * Check for quiet login, either .hushlogin or command given. 673 */ 674 int 675 check_quietlogin(Session *s, const char *command) 676 { 677 char buf[256]; 678 struct passwd *pw = s->pw; 679 struct stat st; 680 681 /* Return 1 if .hushlogin exists or a command given. */ 682 if (command != NULL) 683 return 1; 684 snprintf(buf, sizeof(buf), "%.200s/.hushlogin", pw->pw_dir); 685 if (login_getcapbool(lc, "hushlogin", 0) || stat(buf, &st) >= 0) 686 return 1; 687 return 0; 688 } 689 690 /* 691 * Sets the value of the given variable in the environment. If the variable 692 * already exists, its value is overridden. 693 */ 694 void 695 child_set_env(char ***envp, u_int *envsizep, const char *name, 696 const char *value) 697 { 698 char **env; 699 u_int envsize; 700 u_int i, namelen; 701 702 if (strchr(name, '=') != NULL) { 703 error("Invalid environment variable \"%.100s\"", name); 704 return; 705 } 706 707 /* 708 * Find the slot where the value should be stored. If the variable 709 * already exists, we reuse the slot; otherwise we append a new slot 710 * at the end of the array, expanding if necessary. 711 */ 712 env = *envp; 713 namelen = strlen(name); 714 for (i = 0; env[i]; i++) 715 if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=') 716 break; 717 if (env[i]) { 718 /* Reuse the slot. */ 719 free(env[i]); 720 } else { 721 /* New variable. Expand if necessary. */ 722 envsize = *envsizep; 723 if (i >= envsize - 1) { 724 if (envsize >= 1000) 725 fatal("child_set_env: too many env vars"); 726 envsize += 50; 727 env = (*envp) = xreallocarray(env, envsize, sizeof(char *)); 728 *envsizep = envsize; 729 } 730 /* Need to set the NULL pointer at end of array beyond the new slot. */ 731 env[i + 1] = NULL; 732 } 733 734 /* Allocate space and format the variable in the appropriate slot. */ 735 env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1); 736 snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value); 737 } 738 739 /* 740 * Reads environment variables from the given file and adds/overrides them 741 * into the environment. If the file does not exist, this does nothing. 742 * Otherwise, it must consist of empty lines, comments (line starts with '#') 743 * and assignments of the form name=value. No other forms are allowed. 744 */ 745 static void 746 read_environment_file(char ***env, u_int *envsize, 747 const char *filename) 748 { 749 FILE *f; 750 char buf[4096]; 751 char *cp, *value; 752 u_int lineno = 0; 753 754 f = fopen(filename, "r"); 755 if (!f) 756 return; 757 758 while (fgets(buf, sizeof(buf), f)) { 759 if (++lineno > 1000) 760 fatal("Too many lines in environment file %s", filename); 761 for (cp = buf; *cp == ' ' || *cp == '\t'; cp++) 762 ; 763 if (!*cp || *cp == '#' || *cp == '\n') 764 continue; 765 766 cp[strcspn(cp, "\n")] = '\0'; 767 768 value = strchr(cp, '='); 769 if (value == NULL) { 770 fprintf(stderr, "Bad line %u in %.100s\n", lineno, 771 filename); 772 continue; 773 } 774 /* 775 * Replace the equals sign by nul, and advance value to 776 * the value string. 777 */ 778 *value = '\0'; 779 value++; 780 child_set_env(env, envsize, cp, value); 781 } 782 fclose(f); 783 } 784 785 static char ** 786 do_setup_env(Session *s, const char *shell) 787 { 788 struct ssh *ssh = active_state; /* XXX */ 789 char buf[256]; 790 u_int i, envsize; 791 char **env, *laddr; 792 struct passwd *pw = s->pw; 793 794 /* Initialize the environment. */ 795 envsize = 100; 796 env = xcalloc(envsize, sizeof(char *)); 797 env[0] = NULL; 798 799 #ifdef GSSAPI 800 /* Allow any GSSAPI methods that we've used to alter 801 * the childs environment as they see fit 802 */ 803 ssh_gssapi_do_child(&env, &envsize); 804 #endif 805 806 /* Set basic environment. */ 807 for (i = 0; i < s->num_env; i++) 808 child_set_env(&env, &envsize, s->env[i].name, s->env[i].val); 809 810 child_set_env(&env, &envsize, "USER", pw->pw_name); 811 child_set_env(&env, &envsize, "LOGNAME", pw->pw_name); 812 child_set_env(&env, &envsize, "HOME", pw->pw_dir); 813 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETPATH) < 0) 814 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); 815 else 816 child_set_env(&env, &envsize, "PATH", getenv("PATH")); 817 818 snprintf(buf, sizeof buf, "%.200s/%.50s", _PATH_MAILDIR, pw->pw_name); 819 child_set_env(&env, &envsize, "MAIL", buf); 820 821 /* Normal systems set SHELL by default. */ 822 child_set_env(&env, &envsize, "SHELL", shell); 823 824 if (getenv("TZ")) 825 child_set_env(&env, &envsize, "TZ", getenv("TZ")); 826 827 /* Set custom environment options from RSA authentication. */ 828 while (custom_environment) { 829 struct envstring *ce = custom_environment; 830 char *str = ce->s; 831 832 for (i = 0; str[i] != '=' && str[i]; i++) 833 ; 834 if (str[i] == '=') { 835 str[i] = 0; 836 child_set_env(&env, &envsize, str, str + i + 1); 837 } 838 custom_environment = ce->next; 839 free(ce->s); 840 free(ce); 841 } 842 843 /* SSH_CLIENT deprecated */ 844 snprintf(buf, sizeof buf, "%.50s %d %d", 845 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 846 ssh_local_port(ssh)); 847 child_set_env(&env, &envsize, "SSH_CLIENT", buf); 848 849 laddr = get_local_ipaddr(packet_get_connection_in()); 850 snprintf(buf, sizeof buf, "%.50s %d %.50s %d", 851 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 852 laddr, ssh_local_port(ssh)); 853 free(laddr); 854 child_set_env(&env, &envsize, "SSH_CONNECTION", buf); 855 856 if (s->ttyfd != -1) 857 child_set_env(&env, &envsize, "SSH_TTY", s->tty); 858 if (s->term) 859 child_set_env(&env, &envsize, "TERM", s->term); 860 if (s->display) 861 child_set_env(&env, &envsize, "DISPLAY", s->display); 862 if (original_command) 863 child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND", 864 original_command); 865 #ifdef KRB5 866 if (s->authctxt->krb5_ticket_file) 867 child_set_env(&env, &envsize, "KRB5CCNAME", 868 s->authctxt->krb5_ticket_file); 869 #endif 870 if (auth_sock_name != NULL) 871 child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME, 872 auth_sock_name); 873 874 /* read $HOME/.ssh/environment. */ 875 if (options.permit_user_env) { 876 snprintf(buf, sizeof buf, "%.200s/.ssh/environment", 877 pw->pw_dir); 878 read_environment_file(&env, &envsize, buf); 879 } 880 if (debug_flag) { 881 /* dump the environment */ 882 fprintf(stderr, "Environment:\n"); 883 for (i = 0; env[i]; i++) 884 fprintf(stderr, " %.200s\n", env[i]); 885 } 886 return env; 887 } 888 889 /* 890 * Run $HOME/.ssh/rc, /etc/ssh/sshrc, or xauth (whichever is found 891 * first in this order). 892 */ 893 static void 894 do_rc_files(Session *s, const char *shell) 895 { 896 FILE *f = NULL; 897 char cmd[1024]; 898 int do_xauth; 899 struct stat st; 900 901 do_xauth = 902 s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL; 903 904 /* ignore _PATH_SSH_USER_RC for subsystems and admin forced commands */ 905 if (!s->is_subsystem && options.adm_forced_command == NULL && 906 !no_user_rc && options.permit_user_rc && 907 stat(_PATH_SSH_USER_RC, &st) >= 0) { 908 snprintf(cmd, sizeof cmd, "%s -c '%s %s'", 909 shell, _PATH_BSHELL, _PATH_SSH_USER_RC); 910 if (debug_flag) 911 fprintf(stderr, "Running %s\n", cmd); 912 f = popen(cmd, "w"); 913 if (f) { 914 if (do_xauth) 915 fprintf(f, "%s %s\n", s->auth_proto, 916 s->auth_data); 917 pclose(f); 918 } else 919 fprintf(stderr, "Could not run %s\n", 920 _PATH_SSH_USER_RC); 921 } else if (stat(_PATH_SSH_SYSTEM_RC, &st) >= 0) { 922 if (debug_flag) 923 fprintf(stderr, "Running %s %s\n", _PATH_BSHELL, 924 _PATH_SSH_SYSTEM_RC); 925 f = popen(_PATH_BSHELL " " _PATH_SSH_SYSTEM_RC, "w"); 926 if (f) { 927 if (do_xauth) 928 fprintf(f, "%s %s\n", s->auth_proto, 929 s->auth_data); 930 pclose(f); 931 } else 932 fprintf(stderr, "Could not run %s\n", 933 _PATH_SSH_SYSTEM_RC); 934 } else if (do_xauth && options.xauth_location != NULL) { 935 /* Add authority data to .Xauthority if appropriate. */ 936 if (debug_flag) { 937 fprintf(stderr, 938 "Running %.500s remove %.100s\n", 939 options.xauth_location, s->auth_display); 940 fprintf(stderr, 941 "%.500s add %.100s %.100s %.100s\n", 942 options.xauth_location, s->auth_display, 943 s->auth_proto, s->auth_data); 944 } 945 snprintf(cmd, sizeof cmd, "%s -q -", 946 options.xauth_location); 947 f = popen(cmd, "w"); 948 if (f) { 949 fprintf(f, "remove %s\n", 950 s->auth_display); 951 fprintf(f, "add %s %s %s\n", 952 s->auth_display, s->auth_proto, 953 s->auth_data); 954 pclose(f); 955 } else { 956 fprintf(stderr, "Could not run %s\n", 957 cmd); 958 } 959 } 960 } 961 962 static void 963 do_nologin(struct passwd *pw) 964 { 965 FILE *f = NULL; 966 char buf[1024], *nl, *def_nl = _PATH_NOLOGIN; 967 struct stat sb; 968 969 if (login_getcapbool(lc, "ignorenologin", 0) || pw->pw_uid == 0) 970 return; 971 nl = login_getcapstr(lc, "nologin", def_nl, def_nl); 972 973 if (stat(nl, &sb) == -1) { 974 if (nl != def_nl) 975 free(nl); 976 return; 977 } 978 979 /* /etc/nologin exists. Print its contents if we can and exit. */ 980 logit("User %.100s not allowed because %s exists", pw->pw_name, nl); 981 if ((f = fopen(nl, "r")) != NULL) { 982 while (fgets(buf, sizeof(buf), f)) 983 fputs(buf, stderr); 984 fclose(f); 985 } 986 exit(254); 987 } 988 989 /* 990 * Chroot into a directory after checking it for safety: all path components 991 * must be root-owned directories with strict permissions. 992 */ 993 static void 994 safely_chroot(const char *path, uid_t uid) 995 { 996 const char *cp; 997 char component[PATH_MAX]; 998 struct stat st; 999 1000 if (*path != '/') 1001 fatal("chroot path does not begin at root"); 1002 if (strlen(path) >= sizeof(component)) 1003 fatal("chroot path too long"); 1004 1005 /* 1006 * Descend the path, checking that each component is a 1007 * root-owned directory with strict permissions. 1008 */ 1009 for (cp = path; cp != NULL;) { 1010 if ((cp = strchr(cp, '/')) == NULL) 1011 strlcpy(component, path, sizeof(component)); 1012 else { 1013 cp++; 1014 memcpy(component, path, cp - path); 1015 component[cp - path] = '\0'; 1016 } 1017 1018 debug3("%s: checking '%s'", __func__, component); 1019 1020 if (stat(component, &st) != 0) 1021 fatal("%s: stat(\"%s\"): %s", __func__, 1022 component, strerror(errno)); 1023 if (st.st_uid != 0 || (st.st_mode & 022) != 0) 1024 fatal("bad ownership or modes for chroot " 1025 "directory %s\"%s\"", 1026 cp == NULL ? "" : "component ", component); 1027 if (!S_ISDIR(st.st_mode)) 1028 fatal("chroot path %s\"%s\" is not a directory", 1029 cp == NULL ? "" : "component ", component); 1030 1031 } 1032 1033 if (chdir(path) == -1) 1034 fatal("Unable to chdir to chroot path \"%s\": " 1035 "%s", path, strerror(errno)); 1036 if (chroot(path) == -1) 1037 fatal("chroot(\"%s\"): %s", path, strerror(errno)); 1038 if (chdir("/") == -1) 1039 fatal("%s: chdir(/) after chroot: %s", 1040 __func__, strerror(errno)); 1041 verbose("Changed root directory to \"%s\"", path); 1042 } 1043 1044 /* Set login name, uid, gid, and groups. */ 1045 void 1046 do_setusercontext(struct passwd *pw) 1047 { 1048 char *chroot_path, *tmp; 1049 1050 if (getuid() == 0 || geteuid() == 0) { 1051 /* Prepare groups */ 1052 if (setusercontext(lc, pw, pw->pw_uid, 1053 (LOGIN_SETALL & ~(LOGIN_SETPATH|LOGIN_SETUSER))) < 0) { 1054 perror("unable to set user context"); 1055 exit(1); 1056 } 1057 1058 if (!in_chroot && options.chroot_directory != NULL && 1059 strcasecmp(options.chroot_directory, "none") != 0) { 1060 tmp = tilde_expand_filename(options.chroot_directory, 1061 pw->pw_uid); 1062 chroot_path = percent_expand(tmp, "h", pw->pw_dir, 1063 "u", pw->pw_name, (char *)NULL); 1064 safely_chroot(chroot_path, pw->pw_uid); 1065 free(tmp); 1066 free(chroot_path); 1067 /* Make sure we don't attempt to chroot again */ 1068 free(options.chroot_directory); 1069 options.chroot_directory = NULL; 1070 in_chroot = 1; 1071 } 1072 1073 /* Set UID */ 1074 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUSER) < 0) { 1075 perror("unable to set user context (setuser)"); 1076 exit(1); 1077 } 1078 } else if (options.chroot_directory != NULL && 1079 strcasecmp(options.chroot_directory, "none") != 0) { 1080 fatal("server lacks privileges to chroot to ChrootDirectory"); 1081 } 1082 1083 if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) 1084 fatal("Failed to set uids to %u.", (u_int) pw->pw_uid); 1085 } 1086 1087 static void 1088 do_pwchange(Session *s) 1089 { 1090 fflush(NULL); 1091 fprintf(stderr, "WARNING: Your password has expired.\n"); 1092 if (s->ttyfd != -1) { 1093 fprintf(stderr, 1094 "You must change your password now and login again!\n"); 1095 execl(_PATH_PASSWD_PROG, "passwd", (char *)NULL); 1096 perror("passwd"); 1097 } else { 1098 fprintf(stderr, 1099 "Password change required but no TTY available.\n"); 1100 } 1101 exit(1); 1102 } 1103 1104 static void 1105 child_close_fds(void) 1106 { 1107 extern int auth_sock; 1108 1109 if (auth_sock != -1) { 1110 close(auth_sock); 1111 auth_sock = -1; 1112 } 1113 1114 if (packet_get_connection_in() == packet_get_connection_out()) 1115 close(packet_get_connection_in()); 1116 else { 1117 close(packet_get_connection_in()); 1118 close(packet_get_connection_out()); 1119 } 1120 /* 1121 * Close all descriptors related to channels. They will still remain 1122 * open in the parent. 1123 */ 1124 /* XXX better use close-on-exec? -markus */ 1125 channel_close_all(); 1126 1127 /* 1128 * Close any extra file descriptors. Note that there may still be 1129 * descriptors left by system functions. They will be closed later. 1130 */ 1131 endpwent(); 1132 1133 /* 1134 * Close any extra open file descriptors so that we don't have them 1135 * hanging around in clients. Note that we want to do this after 1136 * initgroups, because at least on Solaris 2.3 it leaves file 1137 * descriptors open. 1138 */ 1139 closefrom(STDERR_FILENO + 1); 1140 } 1141 1142 /* 1143 * Performs common processing for the child, such as setting up the 1144 * environment, closing extra file descriptors, setting the user and group 1145 * ids, and executing the command or shell. 1146 */ 1147 #define ARGV_MAX 10 1148 void 1149 do_child(Session *s, const char *command) 1150 { 1151 extern char **environ; 1152 char **env; 1153 char *argv[ARGV_MAX]; 1154 const char *shell, *shell0; 1155 struct passwd *pw = s->pw; 1156 int r = 0; 1157 1158 /* remove hostkey from the child's memory */ 1159 destroy_sensitive_data(); 1160 1161 /* Force a password change */ 1162 if (s->authctxt->force_pwchange) { 1163 do_setusercontext(pw); 1164 child_close_fds(); 1165 do_pwchange(s); 1166 exit(1); 1167 } 1168 1169 /* 1170 * Login(1) does this as well, and it needs uid 0 for the "-h" 1171 * switch, so we let login(1) to this for us. 1172 */ 1173 do_nologin(pw); 1174 do_setusercontext(pw); 1175 1176 /* 1177 * Get the shell from the password data. An empty shell field is 1178 * legal, and means /bin/sh. 1179 */ 1180 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; 1181 1182 /* 1183 * Make sure $SHELL points to the shell from the password file, 1184 * even if shell is overridden from login.conf 1185 */ 1186 env = do_setup_env(s, shell); 1187 1188 shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell); 1189 1190 /* 1191 * Close the connection descriptors; note that this is the child, and 1192 * the server will still have the socket open, and it is important 1193 * that we do not shutdown it. Note that the descriptors cannot be 1194 * closed before building the environment, as we call 1195 * ssh_remote_ipaddr there. 1196 */ 1197 child_close_fds(); 1198 1199 /* 1200 * Must take new environment into use so that .ssh/rc, 1201 * /etc/ssh/sshrc and xauth are run in the proper environment. 1202 */ 1203 environ = env; 1204 1205 #ifdef KRB5 1206 /* 1207 * At this point, we check to see if AFS is active and if we have 1208 * a valid Kerberos 5 TGT. If so, it seems like a good idea to see 1209 * if we can (and need to) extend the ticket into an AFS token. If 1210 * we don't do this, we run into potential problems if the user's 1211 * home directory is in AFS and it's not world-readable. 1212 */ 1213 1214 if (options.kerberos_get_afs_token && k_hasafs() && 1215 (s->authctxt->krb5_ctx != NULL)) { 1216 char cell[64]; 1217 1218 debug("Getting AFS token"); 1219 1220 k_setpag(); 1221 1222 if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0) 1223 krb5_afslog(s->authctxt->krb5_ctx, 1224 s->authctxt->krb5_fwd_ccache, cell, NULL); 1225 1226 krb5_afslog_home(s->authctxt->krb5_ctx, 1227 s->authctxt->krb5_fwd_ccache, NULL, NULL, pw->pw_dir); 1228 } 1229 #endif 1230 1231 /* Change current directory to the user's home directory. */ 1232 if (chdir(pw->pw_dir) < 0) { 1233 /* Suppress missing homedir warning for chroot case */ 1234 r = login_getcapbool(lc, "requirehome", 0); 1235 if (r || !in_chroot) { 1236 fprintf(stderr, "Could not chdir to home " 1237 "directory %s: %s\n", pw->pw_dir, 1238 strerror(errno)); 1239 } 1240 if (r) 1241 exit(1); 1242 } 1243 1244 closefrom(STDERR_FILENO + 1); 1245 1246 do_rc_files(s, shell); 1247 1248 /* restore SIGPIPE for child */ 1249 signal(SIGPIPE, SIG_DFL); 1250 1251 if (s->is_subsystem == SUBSYSTEM_INT_SFTP_ERROR) { 1252 printf("This service allows sftp connections only.\n"); 1253 fflush(NULL); 1254 exit(1); 1255 } else if (s->is_subsystem == SUBSYSTEM_INT_SFTP) { 1256 extern int optind, optreset; 1257 int i; 1258 char *p, *args; 1259 1260 setproctitle("%s@%s", s->pw->pw_name, INTERNAL_SFTP_NAME); 1261 args = xstrdup(command ? command : "sftp-server"); 1262 for (i = 0, (p = strtok(args, " ")); p; (p = strtok(NULL, " "))) 1263 if (i < ARGV_MAX - 1) 1264 argv[i++] = p; 1265 argv[i] = NULL; 1266 optind = optreset = 1; 1267 __progname = argv[0]; 1268 exit(sftp_server_main(i, argv, s->pw)); 1269 } 1270 1271 fflush(NULL); 1272 1273 /* Get the last component of the shell name. */ 1274 if ((shell0 = strrchr(shell, '/')) != NULL) 1275 shell0++; 1276 else 1277 shell0 = shell; 1278 1279 /* 1280 * If we have no command, execute the shell. In this case, the shell 1281 * name to be passed in argv[0] is preceded by '-' to indicate that 1282 * this is a login shell. 1283 */ 1284 if (!command) { 1285 char argv0[256]; 1286 1287 /* Start the shell. Set initial character to '-'. */ 1288 argv0[0] = '-'; 1289 1290 if (strlcpy(argv0 + 1, shell0, sizeof(argv0) - 1) 1291 >= sizeof(argv0) - 1) { 1292 errno = EINVAL; 1293 perror(shell); 1294 exit(1); 1295 } 1296 1297 /* Execute the shell. */ 1298 argv[0] = argv0; 1299 argv[1] = NULL; 1300 execve(shell, argv, env); 1301 1302 /* Executing the shell failed. */ 1303 perror(shell); 1304 exit(1); 1305 } 1306 /* 1307 * Execute the command using the user's shell. This uses the -c 1308 * option to execute the command. 1309 */ 1310 argv[0] = (char *) shell0; 1311 argv[1] = "-c"; 1312 argv[2] = (char *) command; 1313 argv[3] = NULL; 1314 execve(shell, argv, env); 1315 perror(shell); 1316 exit(1); 1317 } 1318 1319 void 1320 session_unused(int id) 1321 { 1322 debug3("%s: session id %d unused", __func__, id); 1323 if (id >= options.max_sessions || 1324 id >= sessions_nalloc) { 1325 fatal("%s: insane session id %d (max %d nalloc %d)", 1326 __func__, id, options.max_sessions, sessions_nalloc); 1327 } 1328 memset(&sessions[id], 0, sizeof(*sessions)); 1329 sessions[id].self = id; 1330 sessions[id].used = 0; 1331 sessions[id].chanid = -1; 1332 sessions[id].ptyfd = -1; 1333 sessions[id].ttyfd = -1; 1334 sessions[id].ptymaster = -1; 1335 sessions[id].x11_chanids = NULL; 1336 sessions[id].next_unused = sessions_first_unused; 1337 sessions_first_unused = id; 1338 } 1339 1340 Session * 1341 session_new(void) 1342 { 1343 Session *s, *tmp; 1344 1345 if (sessions_first_unused == -1) { 1346 if (sessions_nalloc >= options.max_sessions) 1347 return NULL; 1348 debug2("%s: allocate (allocated %d max %d)", 1349 __func__, sessions_nalloc, options.max_sessions); 1350 tmp = xreallocarray(sessions, sessions_nalloc + 1, 1351 sizeof(*sessions)); 1352 if (tmp == NULL) { 1353 error("%s: cannot allocate %d sessions", 1354 __func__, sessions_nalloc + 1); 1355 return NULL; 1356 } 1357 sessions = tmp; 1358 session_unused(sessions_nalloc++); 1359 } 1360 1361 if (sessions_first_unused >= sessions_nalloc || 1362 sessions_first_unused < 0) { 1363 fatal("%s: insane first_unused %d max %d nalloc %d", 1364 __func__, sessions_first_unused, options.max_sessions, 1365 sessions_nalloc); 1366 } 1367 1368 s = &sessions[sessions_first_unused]; 1369 if (s->used) { 1370 fatal("%s: session %d already used", 1371 __func__, sessions_first_unused); 1372 } 1373 sessions_first_unused = s->next_unused; 1374 s->used = 1; 1375 s->next_unused = -1; 1376 debug("session_new: session %d", s->self); 1377 1378 return s; 1379 } 1380 1381 static void 1382 session_dump(void) 1383 { 1384 int i; 1385 for (i = 0; i < sessions_nalloc; i++) { 1386 Session *s = &sessions[i]; 1387 1388 debug("dump: used %d next_unused %d session %d %p " 1389 "channel %d pid %ld", 1390 s->used, 1391 s->next_unused, 1392 s->self, 1393 s, 1394 s->chanid, 1395 (long)s->pid); 1396 } 1397 } 1398 1399 int 1400 session_open(Authctxt *authctxt, int chanid) 1401 { 1402 Session *s = session_new(); 1403 debug("session_open: channel %d", chanid); 1404 if (s == NULL) { 1405 error("no more sessions"); 1406 return 0; 1407 } 1408 s->authctxt = authctxt; 1409 s->pw = authctxt->pw; 1410 if (s->pw == NULL || !authctxt->valid) 1411 fatal("no user for session %d", s->self); 1412 debug("session_open: session %d: link with channel %d", s->self, chanid); 1413 s->chanid = chanid; 1414 return 1; 1415 } 1416 1417 Session * 1418 session_by_tty(char *tty) 1419 { 1420 int i; 1421 for (i = 0; i < sessions_nalloc; i++) { 1422 Session *s = &sessions[i]; 1423 if (s->used && s->ttyfd != -1 && strcmp(s->tty, tty) == 0) { 1424 debug("session_by_tty: session %d tty %s", i, tty); 1425 return s; 1426 } 1427 } 1428 debug("session_by_tty: unknown tty %.100s", tty); 1429 session_dump(); 1430 return NULL; 1431 } 1432 1433 static Session * 1434 session_by_channel(int id) 1435 { 1436 int i; 1437 for (i = 0; i < sessions_nalloc; i++) { 1438 Session *s = &sessions[i]; 1439 if (s->used && s->chanid == id) { 1440 debug("session_by_channel: session %d channel %d", 1441 i, id); 1442 return s; 1443 } 1444 } 1445 debug("session_by_channel: unknown channel %d", id); 1446 session_dump(); 1447 return NULL; 1448 } 1449 1450 static Session * 1451 session_by_x11_channel(int id) 1452 { 1453 int i, j; 1454 1455 for (i = 0; i < sessions_nalloc; i++) { 1456 Session *s = &sessions[i]; 1457 1458 if (s->x11_chanids == NULL || !s->used) 1459 continue; 1460 for (j = 0; s->x11_chanids[j] != -1; j++) { 1461 if (s->x11_chanids[j] == id) { 1462 debug("session_by_x11_channel: session %d " 1463 "channel %d", s->self, id); 1464 return s; 1465 } 1466 } 1467 } 1468 debug("session_by_x11_channel: unknown channel %d", id); 1469 session_dump(); 1470 return NULL; 1471 } 1472 1473 static Session * 1474 session_by_pid(pid_t pid) 1475 { 1476 int i; 1477 debug("session_by_pid: pid %ld", (long)pid); 1478 for (i = 0; i < sessions_nalloc; i++) { 1479 Session *s = &sessions[i]; 1480 if (s->used && s->pid == pid) 1481 return s; 1482 } 1483 error("session_by_pid: unknown pid %ld", (long)pid); 1484 session_dump(); 1485 return NULL; 1486 } 1487 1488 static int 1489 session_window_change_req(Session *s) 1490 { 1491 s->col = packet_get_int(); 1492 s->row = packet_get_int(); 1493 s->xpixel = packet_get_int(); 1494 s->ypixel = packet_get_int(); 1495 packet_check_eom(); 1496 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 1497 return 1; 1498 } 1499 1500 static int 1501 session_pty_req(Session *s) 1502 { 1503 u_int len; 1504 int n_bytes; 1505 1506 if (no_pty_flag || !options.permit_tty) { 1507 debug("Allocating a pty not permitted for this authentication."); 1508 return 0; 1509 } 1510 if (s->ttyfd != -1) { 1511 packet_disconnect("Protocol error: you already have a pty."); 1512 return 0; 1513 } 1514 1515 s->term = packet_get_string(&len); 1516 s->col = packet_get_int(); 1517 s->row = packet_get_int(); 1518 s->xpixel = packet_get_int(); 1519 s->ypixel = packet_get_int(); 1520 1521 if (strcmp(s->term, "") == 0) { 1522 free(s->term); 1523 s->term = NULL; 1524 } 1525 1526 /* Allocate a pty and open it. */ 1527 debug("Allocating pty."); 1528 if (!PRIVSEP(pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, 1529 sizeof(s->tty)))) { 1530 free(s->term); 1531 s->term = NULL; 1532 s->ptyfd = -1; 1533 s->ttyfd = -1; 1534 error("session_pty_req: session %d alloc failed", s->self); 1535 return 0; 1536 } 1537 debug("session_pty_req: session %d alloc %s", s->self, s->tty); 1538 1539 n_bytes = packet_remaining(); 1540 tty_parse_modes(s->ttyfd, &n_bytes); 1541 1542 if (!use_privsep) 1543 pty_setowner(s->pw, s->tty); 1544 1545 /* Set window size from the packet. */ 1546 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 1547 1548 packet_check_eom(); 1549 session_proctitle(s); 1550 return 1; 1551 } 1552 1553 static int 1554 session_subsystem_req(Session *s) 1555 { 1556 struct stat st; 1557 u_int len; 1558 int success = 0; 1559 char *prog, *cmd; 1560 u_int i; 1561 1562 s->subsys = packet_get_string(&len); 1563 packet_check_eom(); 1564 debug2("subsystem request for %.100s by user %s", s->subsys, 1565 s->pw->pw_name); 1566 1567 for (i = 0; i < options.num_subsystems; i++) { 1568 if (strcmp(s->subsys, options.subsystem_name[i]) == 0) { 1569 prog = options.subsystem_command[i]; 1570 cmd = options.subsystem_args[i]; 1571 if (strcmp(INTERNAL_SFTP_NAME, prog) == 0) { 1572 s->is_subsystem = SUBSYSTEM_INT_SFTP; 1573 debug("subsystem: %s", prog); 1574 } else { 1575 if (stat(prog, &st) < 0) 1576 debug("subsystem: cannot stat %s: %s", 1577 prog, strerror(errno)); 1578 s->is_subsystem = SUBSYSTEM_EXT; 1579 debug("subsystem: exec() %s", cmd); 1580 } 1581 success = do_exec(s, cmd) == 0; 1582 break; 1583 } 1584 } 1585 1586 if (!success) 1587 logit("subsystem request for %.100s by user %s failed, " 1588 "subsystem not found", s->subsys, s->pw->pw_name); 1589 1590 return success; 1591 } 1592 1593 static int 1594 session_x11_req(Session *s) 1595 { 1596 int success; 1597 1598 if (s->auth_proto != NULL || s->auth_data != NULL) { 1599 error("session_x11_req: session %d: " 1600 "x11 forwarding already active", s->self); 1601 return 0; 1602 } 1603 s->single_connection = packet_get_char(); 1604 s->auth_proto = packet_get_string(NULL); 1605 s->auth_data = packet_get_string(NULL); 1606 s->screen = packet_get_int(); 1607 packet_check_eom(); 1608 1609 if (xauth_valid_string(s->auth_proto) && 1610 xauth_valid_string(s->auth_data)) 1611 success = session_setup_x11fwd(s); 1612 else { 1613 success = 0; 1614 error("Invalid X11 forwarding data"); 1615 } 1616 if (!success) { 1617 free(s->auth_proto); 1618 free(s->auth_data); 1619 s->auth_proto = NULL; 1620 s->auth_data = NULL; 1621 } 1622 return success; 1623 } 1624 1625 static int 1626 session_shell_req(Session *s) 1627 { 1628 packet_check_eom(); 1629 return do_exec(s, NULL) == 0; 1630 } 1631 1632 static int 1633 session_exec_req(Session *s) 1634 { 1635 u_int len, success; 1636 1637 char *command = packet_get_string(&len); 1638 packet_check_eom(); 1639 success = do_exec(s, command) == 0; 1640 free(command); 1641 return success; 1642 } 1643 1644 static int 1645 session_break_req(Session *s) 1646 { 1647 1648 packet_get_int(); /* ignored */ 1649 packet_check_eom(); 1650 1651 if (s->ptymaster == -1 || tcsendbreak(s->ptymaster, 0) < 0) 1652 return 0; 1653 return 1; 1654 } 1655 1656 static int 1657 session_env_req(Session *s) 1658 { 1659 char *name, *val; 1660 u_int name_len, val_len, i; 1661 1662 name = packet_get_cstring(&name_len); 1663 val = packet_get_cstring(&val_len); 1664 packet_check_eom(); 1665 1666 /* Don't set too many environment variables */ 1667 if (s->num_env > 128) { 1668 debug2("Ignoring env request %s: too many env vars", name); 1669 goto fail; 1670 } 1671 1672 for (i = 0; i < options.num_accept_env; i++) { 1673 if (match_pattern(name, options.accept_env[i])) { 1674 debug2("Setting env %d: %s=%s", s->num_env, name, val); 1675 s->env = xreallocarray(s->env, s->num_env + 1, 1676 sizeof(*s->env)); 1677 s->env[s->num_env].name = name; 1678 s->env[s->num_env].val = val; 1679 s->num_env++; 1680 return (1); 1681 } 1682 } 1683 debug2("Ignoring env request %s: disallowed name", name); 1684 1685 fail: 1686 free(name); 1687 free(val); 1688 return (0); 1689 } 1690 1691 static int 1692 session_auth_agent_req(Session *s) 1693 { 1694 static int called = 0; 1695 packet_check_eom(); 1696 if (no_agent_forwarding_flag || !options.allow_agent_forwarding) { 1697 debug("session_auth_agent_req: no_agent_forwarding_flag"); 1698 return 0; 1699 } 1700 if (called) { 1701 return 0; 1702 } else { 1703 called = 1; 1704 return auth_input_request_forwarding(s->pw); 1705 } 1706 } 1707 1708 int 1709 session_input_channel_req(Channel *c, const char *rtype) 1710 { 1711 int success = 0; 1712 Session *s; 1713 1714 if ((s = session_by_channel(c->self)) == NULL) { 1715 logit("session_input_channel_req: no session %d req %.100s", 1716 c->self, rtype); 1717 return 0; 1718 } 1719 debug("session_input_channel_req: session %d req %s", s->self, rtype); 1720 1721 /* 1722 * a session is in LARVAL state until a shell, a command 1723 * or a subsystem is executed 1724 */ 1725 if (c->type == SSH_CHANNEL_LARVAL) { 1726 if (strcmp(rtype, "shell") == 0) { 1727 success = session_shell_req(s); 1728 } else if (strcmp(rtype, "exec") == 0) { 1729 success = session_exec_req(s); 1730 } else if (strcmp(rtype, "pty-req") == 0) { 1731 success = session_pty_req(s); 1732 } else if (strcmp(rtype, "x11-req") == 0) { 1733 success = session_x11_req(s); 1734 } else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) { 1735 success = session_auth_agent_req(s); 1736 } else if (strcmp(rtype, "subsystem") == 0) { 1737 success = session_subsystem_req(s); 1738 } else if (strcmp(rtype, "env") == 0) { 1739 success = session_env_req(s); 1740 } 1741 } 1742 if (strcmp(rtype, "window-change") == 0) { 1743 success = session_window_change_req(s); 1744 } else if (strcmp(rtype, "break") == 0) { 1745 success = session_break_req(s); 1746 } 1747 1748 return success; 1749 } 1750 1751 void 1752 session_set_fds(Session *s, int fdin, int fdout, int fderr, int ignore_fderr, 1753 int is_tty) 1754 { 1755 /* 1756 * now that have a child and a pipe to the child, 1757 * we can activate our channel and register the fd's 1758 */ 1759 if (s->chanid == -1) 1760 fatal("no channel for session %d", s->self); 1761 channel_set_fds(s->chanid, 1762 fdout, fdin, fderr, 1763 ignore_fderr ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ, 1764 1, is_tty, CHAN_SES_WINDOW_DEFAULT); 1765 } 1766 1767 /* 1768 * Function to perform pty cleanup. Also called if we get aborted abnormally 1769 * (e.g., due to a dropped connection). 1770 */ 1771 void 1772 session_pty_cleanup2(Session *s) 1773 { 1774 if (s == NULL) { 1775 error("session_pty_cleanup: no session"); 1776 return; 1777 } 1778 if (s->ttyfd == -1) 1779 return; 1780 1781 debug("session_pty_cleanup: session %d release %s", s->self, s->tty); 1782 1783 /* Record that the user has logged out. */ 1784 if (s->pid != 0) 1785 record_logout(s->pid, s->tty); 1786 1787 /* Release the pseudo-tty. */ 1788 if (getuid() == 0) 1789 pty_release(s->tty); 1790 1791 /* 1792 * Close the server side of the socket pairs. We must do this after 1793 * the pty cleanup, so that another process doesn't get this pty 1794 * while we're still cleaning up. 1795 */ 1796 if (s->ptymaster != -1 && close(s->ptymaster) < 0) 1797 error("close(s->ptymaster/%d): %s", 1798 s->ptymaster, strerror(errno)); 1799 1800 /* unlink pty from session */ 1801 s->ttyfd = -1; 1802 } 1803 1804 void 1805 session_pty_cleanup(Session *s) 1806 { 1807 PRIVSEP(session_pty_cleanup2(s)); 1808 } 1809 1810 static char * 1811 sig2name(int sig) 1812 { 1813 #define SSH_SIG(x) if (sig == SIG ## x) return #x 1814 SSH_SIG(ABRT); 1815 SSH_SIG(ALRM); 1816 SSH_SIG(FPE); 1817 SSH_SIG(HUP); 1818 SSH_SIG(ILL); 1819 SSH_SIG(INT); 1820 SSH_SIG(KILL); 1821 SSH_SIG(PIPE); 1822 SSH_SIG(QUIT); 1823 SSH_SIG(SEGV); 1824 SSH_SIG(TERM); 1825 SSH_SIG(USR1); 1826 SSH_SIG(USR2); 1827 #undef SSH_SIG 1828 return "SIG@openssh.com"; 1829 } 1830 1831 static void 1832 session_close_x11(int id) 1833 { 1834 Channel *c; 1835 1836 if ((c = channel_by_id(id)) == NULL) { 1837 debug("session_close_x11: x11 channel %d missing", id); 1838 } else { 1839 /* Detach X11 listener */ 1840 debug("session_close_x11: detach x11 channel %d", id); 1841 channel_cancel_cleanup(id); 1842 if (c->ostate != CHAN_OUTPUT_CLOSED) 1843 chan_mark_dead(c); 1844 } 1845 } 1846 1847 static void 1848 session_close_single_x11(int id, void *arg) 1849 { 1850 Session *s; 1851 u_int i; 1852 1853 debug3("session_close_single_x11: channel %d", id); 1854 channel_cancel_cleanup(id); 1855 if ((s = session_by_x11_channel(id)) == NULL) 1856 fatal("session_close_single_x11: no x11 channel %d", id); 1857 for (i = 0; s->x11_chanids[i] != -1; i++) { 1858 debug("session_close_single_x11: session %d: " 1859 "closing channel %d", s->self, s->x11_chanids[i]); 1860 /* 1861 * The channel "id" is already closing, but make sure we 1862 * close all of its siblings. 1863 */ 1864 if (s->x11_chanids[i] != id) 1865 session_close_x11(s->x11_chanids[i]); 1866 } 1867 free(s->x11_chanids); 1868 s->x11_chanids = NULL; 1869 free(s->display); 1870 s->display = NULL; 1871 free(s->auth_proto); 1872 s->auth_proto = NULL; 1873 free(s->auth_data); 1874 s->auth_data = NULL; 1875 free(s->auth_display); 1876 s->auth_display = NULL; 1877 } 1878 1879 static void 1880 session_exit_message(Session *s, int status) 1881 { 1882 Channel *c; 1883 1884 if ((c = channel_lookup(s->chanid)) == NULL) 1885 fatal("session_exit_message: session %d: no channel %d", 1886 s->self, s->chanid); 1887 debug("session_exit_message: session %d channel %d pid %ld", 1888 s->self, s->chanid, (long)s->pid); 1889 1890 if (WIFEXITED(status)) { 1891 channel_request_start(s->chanid, "exit-status", 0); 1892 packet_put_int(WEXITSTATUS(status)); 1893 packet_send(); 1894 } else if (WIFSIGNALED(status)) { 1895 channel_request_start(s->chanid, "exit-signal", 0); 1896 packet_put_cstring(sig2name(WTERMSIG(status))); 1897 packet_put_char(WCOREDUMP(status)? 1 : 0); 1898 packet_put_cstring(""); 1899 packet_put_cstring(""); 1900 packet_send(); 1901 } else { 1902 /* Some weird exit cause. Just exit. */ 1903 packet_disconnect("wait returned status %04x.", status); 1904 } 1905 1906 /* disconnect channel */ 1907 debug("session_exit_message: release channel %d", s->chanid); 1908 1909 /* 1910 * Adjust cleanup callback attachment to send close messages when 1911 * the channel gets EOF. The session will be then be closed 1912 * by session_close_by_channel when the childs close their fds. 1913 */ 1914 channel_register_cleanup(c->self, session_close_by_channel, 1); 1915 1916 /* 1917 * emulate a write failure with 'chan_write_failed', nobody will be 1918 * interested in data we write. 1919 * Note that we must not call 'chan_read_failed', since there could 1920 * be some more data waiting in the pipe. 1921 */ 1922 if (c->ostate != CHAN_OUTPUT_CLOSED) 1923 chan_write_failed(c); 1924 } 1925 1926 void 1927 session_close(Session *s) 1928 { 1929 struct ssh *ssh = active_state; /* XXX */ 1930 u_int i; 1931 1932 verbose("Close session: user %s from %.200s port %d id %d", 1933 s->pw->pw_name, 1934 ssh_remote_ipaddr(ssh), 1935 ssh_remote_port(ssh), 1936 s->self); 1937 1938 if (s->ttyfd != -1) 1939 session_pty_cleanup(s); 1940 free(s->term); 1941 free(s->display); 1942 free(s->x11_chanids); 1943 free(s->auth_display); 1944 free(s->auth_data); 1945 free(s->auth_proto); 1946 free(s->subsys); 1947 if (s->env != NULL) { 1948 for (i = 0; i < s->num_env; i++) { 1949 free(s->env[i].name); 1950 free(s->env[i].val); 1951 } 1952 free(s->env); 1953 } 1954 session_proctitle(s); 1955 session_unused(s->self); 1956 } 1957 1958 void 1959 session_close_by_pid(pid_t pid, int status) 1960 { 1961 Session *s = session_by_pid(pid); 1962 if (s == NULL) { 1963 debug("session_close_by_pid: no session for pid %ld", 1964 (long)pid); 1965 return; 1966 } 1967 if (s->chanid != -1) 1968 session_exit_message(s, status); 1969 if (s->ttyfd != -1) 1970 session_pty_cleanup(s); 1971 s->pid = 0; 1972 } 1973 1974 /* 1975 * this is called when a channel dies before 1976 * the session 'child' itself dies 1977 */ 1978 void 1979 session_close_by_channel(int id, void *arg) 1980 { 1981 Session *s = session_by_channel(id); 1982 u_int i; 1983 1984 if (s == NULL) { 1985 debug("session_close_by_channel: no session for id %d", id); 1986 return; 1987 } 1988 debug("session_close_by_channel: channel %d child %ld", 1989 id, (long)s->pid); 1990 if (s->pid != 0) { 1991 debug("session_close_by_channel: channel %d: has child", id); 1992 /* 1993 * delay detach of session, but release pty, since 1994 * the fd's to the child are already closed 1995 */ 1996 if (s->ttyfd != -1) 1997 session_pty_cleanup(s); 1998 return; 1999 } 2000 /* detach by removing callback */ 2001 channel_cancel_cleanup(s->chanid); 2002 2003 /* Close any X11 listeners associated with this session */ 2004 if (s->x11_chanids != NULL) { 2005 for (i = 0; s->x11_chanids[i] != -1; i++) { 2006 session_close_x11(s->x11_chanids[i]); 2007 s->x11_chanids[i] = -1; 2008 } 2009 } 2010 2011 s->chanid = -1; 2012 session_close(s); 2013 } 2014 2015 void 2016 session_destroy_all(void (*closefunc)(Session *)) 2017 { 2018 int i; 2019 for (i = 0; i < sessions_nalloc; i++) { 2020 Session *s = &sessions[i]; 2021 if (s->used) { 2022 if (closefunc != NULL) 2023 closefunc(s); 2024 else 2025 session_close(s); 2026 } 2027 } 2028 } 2029 2030 static char * 2031 session_tty_list(void) 2032 { 2033 static char buf[1024]; 2034 int i; 2035 buf[0] = '\0'; 2036 for (i = 0; i < sessions_nalloc; i++) { 2037 Session *s = &sessions[i]; 2038 if (s->used && s->ttyfd != -1) { 2039 if (buf[0] != '\0') 2040 strlcat(buf, ",", sizeof buf); 2041 strlcat(buf, strrchr(s->tty, '/') + 1, sizeof buf); 2042 } 2043 } 2044 if (buf[0] == '\0') 2045 strlcpy(buf, "notty", sizeof buf); 2046 return buf; 2047 } 2048 2049 void 2050 session_proctitle(Session *s) 2051 { 2052 if (s->pw == NULL) 2053 error("no user for session %d", s->self); 2054 else 2055 setproctitle("%s@%s", s->pw->pw_name, session_tty_list()); 2056 } 2057 2058 int 2059 session_setup_x11fwd(Session *s) 2060 { 2061 struct stat st; 2062 char display[512], auth_display[512]; 2063 char hostname[NI_MAXHOST]; 2064 u_int i; 2065 2066 if (no_x11_forwarding_flag) { 2067 packet_send_debug("X11 forwarding disabled in user configuration file."); 2068 return 0; 2069 } 2070 if (!options.x11_forwarding) { 2071 debug("X11 forwarding disabled in server configuration file."); 2072 return 0; 2073 } 2074 if (options.xauth_location == NULL || 2075 (stat(options.xauth_location, &st) == -1)) { 2076 packet_send_debug("No xauth program; cannot forward with spoofing."); 2077 return 0; 2078 } 2079 if (s->display != NULL) { 2080 debug("X11 display already set."); 2081 return 0; 2082 } 2083 if (x11_create_display_inet(options.x11_display_offset, 2084 options.x11_use_localhost, s->single_connection, 2085 &s->display_number, &s->x11_chanids) == -1) { 2086 debug("x11_create_display_inet failed."); 2087 return 0; 2088 } 2089 for (i = 0; s->x11_chanids[i] != -1; i++) { 2090 channel_register_cleanup(s->x11_chanids[i], 2091 session_close_single_x11, 0); 2092 } 2093 2094 /* Set up a suitable value for the DISPLAY variable. */ 2095 if (gethostname(hostname, sizeof(hostname)) < 0) 2096 fatal("gethostname: %.100s", strerror(errno)); 2097 /* 2098 * auth_display must be used as the displayname when the 2099 * authorization entry is added with xauth(1). This will be 2100 * different than the DISPLAY string for localhost displays. 2101 */ 2102 if (options.x11_use_localhost) { 2103 snprintf(display, sizeof display, "localhost:%u.%u", 2104 s->display_number, s->screen); 2105 snprintf(auth_display, sizeof auth_display, "unix:%u.%u", 2106 s->display_number, s->screen); 2107 s->display = xstrdup(display); 2108 s->auth_display = xstrdup(auth_display); 2109 } else { 2110 snprintf(display, sizeof display, "%.400s:%u.%u", hostname, 2111 s->display_number, s->screen); 2112 s->display = xstrdup(display); 2113 s->auth_display = xstrdup(display); 2114 } 2115 2116 return 1; 2117 } 2118 2119 static void 2120 do_authenticated2(Authctxt *authctxt) 2121 { 2122 server_loop2(authctxt); 2123 } 2124 2125 void 2126 do_cleanup(Authctxt *authctxt) 2127 { 2128 static int called = 0; 2129 2130 debug("do_cleanup"); 2131 2132 /* no cleanup if we're in the child for login shell */ 2133 if (is_child) 2134 return; 2135 2136 /* avoid double cleanup */ 2137 if (called) 2138 return; 2139 called = 1; 2140 2141 if (authctxt == NULL || !authctxt->authenticated) 2142 return; 2143 #ifdef KRB5 2144 if (options.kerberos_ticket_cleanup && 2145 authctxt->krb5_ctx) 2146 krb5_cleanup_proc(authctxt); 2147 #endif 2148 2149 #ifdef GSSAPI 2150 if (options.gss_cleanup_creds) 2151 ssh_gssapi_cleanup_creds(); 2152 #endif 2153 2154 /* remove agent socket */ 2155 auth_sock_cleanup_proc(authctxt->pw); 2156 2157 /* 2158 * Cleanup ptys/utmp only if privsep is disabled, 2159 * or if running in monitor. 2160 */ 2161 if (!use_privsep || mm_is_monitor()) 2162 session_destroy_all(session_pty_cleanup2); 2163 } 2164 2165 /* Return a name for the remote host that fits inside utmp_size */ 2166 2167 const char * 2168 session_get_remote_name_or_ip(struct ssh *ssh, u_int utmp_size, int use_dns) 2169 { 2170 const char *remote = ""; 2171 2172 if (utmp_size > 0) 2173 remote = auth_get_canonical_hostname(ssh, use_dns); 2174 if (utmp_size == 0 || strlen(remote) > utmp_size) 2175 remote = ssh_remote_ipaddr(ssh); 2176 return remote; 2177 } 2178 2179