1 /* $OpenBSD: session.c,v 1.277 2015/01/16 06:40:12 deraadt Exp $ */ 2 /* 3 * Copyright (c) 1995 Tatu Ylonen <ylo (at) 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 <errno.h> 50 #include <fcntl.h> 51 #include <grp.h> 52 #include <netdb.h> 53 #ifdef HAVE_PATHS_H 54 #include <paths.h> 55 #endif 56 #include <pwd.h> 57 #include <signal.h> 58 #include <stdarg.h> 59 #include <stdio.h> 60 #include <stdlib.h> 61 #include <string.h> 62 #include <unistd.h> 63 #include <limits.h> 64 65 #include "openbsd-compat/sys-queue.h" 66 #include "xmalloc.h" 67 #include "ssh.h" 68 #include "ssh1.h" 69 #include "ssh2.h" 70 #include "sshpty.h" 71 #include "packet.h" 72 #include "buffer.h" 73 #include "match.h" 74 #include "uidswap.h" 75 #include "compat.h" 76 #include "channels.h" 77 #include "key.h" 78 #include "cipher.h" 79 #ifdef GSSAPI 80 #include "ssh-gss.h" 81 #endif 82 #include "hostfile.h" 83 #include "auth.h" 84 #include "auth-options.h" 85 #include "authfd.h" 86 #include "pathnames.h" 87 #include "log.h" 88 #include "misc.h" 89 #include "servconf.h" 90 #include "sshlogin.h" 91 #include "serverloop.h" 92 #include "canohost.h" 93 #include "session.h" 94 #include "kex.h" 95 #include "monitor_wrap.h" 96 #include "sftp.h" 97 98 #if defined(KRB5) && defined(USE_AFS) 99 #include <kafs.h> 100 #endif 101 102 #ifdef WITH_SELINUX 103 #include <selinux/selinux.h> 104 #endif 105 106 #define IS_INTERNAL_SFTP(c) \ 107 (!strncmp(c, INTERNAL_SFTP_NAME, sizeof(INTERNAL_SFTP_NAME) - 1) && \ 108 (c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\0' || \ 109 c[sizeof(INTERNAL_SFTP_NAME) - 1] == ' ' || \ 110 c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\t')) 111 112 /* func */ 113 114 Session *session_new(void); 115 void session_set_fds(Session *, int, int, int, int, int); 116 void session_pty_cleanup(Session *); 117 void session_proctitle(Session *); 118 int session_setup_x11fwd(Session *); 119 int do_exec_pty(Session *, const char *); 120 int do_exec_no_pty(Session *, const char *); 121 int do_exec(Session *, const char *); 122 void do_login(Session *, const char *); 123 #ifdef LOGIN_NEEDS_UTMPX 124 static void do_pre_login(Session *s); 125 #endif 126 void do_child(Session *, const char *); 127 void do_motd(void); 128 int check_quietlogin(Session *, const char *); 129 130 static void do_authenticated1(Authctxt *); 131 static void do_authenticated2(Authctxt *); 132 133 static int session_pty_req(Session *); 134 135 /* import */ 136 extern ServerOptions options; 137 extern char *__progname; 138 extern int log_stderr; 139 extern int debug_flag; 140 extern u_int utmp_len; 141 extern int startup_pipe; 142 extern void destroy_sensitive_data(void); 143 extern Buffer loginmsg; 144 145 /* original command from peer. */ 146 const char *original_command = NULL; 147 148 /* data */ 149 static int sessions_first_unused = -1; 150 static int sessions_nalloc = 0; 151 static Session *sessions = NULL; 152 153 #define SUBSYSTEM_NONE 0 154 #define SUBSYSTEM_EXT 1 155 #define SUBSYSTEM_INT_SFTP 2 156 #define SUBSYSTEM_INT_SFTP_ERROR 3 157 158 #ifdef HAVE_LOGIN_CAP 159 login_cap_t *lc; 160 #endif 161 162 static int is_child = 0; 163 164 /* Name and directory of socket for authentication agent forwarding. */ 165 static char *auth_sock_name = NULL; 166 static char *auth_sock_dir = NULL; 167 168 /* removes the agent forwarding socket */ 169 170 static void 171 auth_sock_cleanup_proc(struct passwd *pw) 172 { 173 if (auth_sock_name != NULL) { 174 temporarily_use_uid(pw); 175 unlink(auth_sock_name); 176 rmdir(auth_sock_dir); 177 auth_sock_name = NULL; 178 restore_uid(); 179 } 180 } 181 182 static int 183 auth_input_request_forwarding(struct passwd * pw) 184 { 185 Channel *nc; 186 int sock = -1; 187 188 if (auth_sock_name != NULL) { 189 error("authentication forwarding requested twice."); 190 return 0; 191 } 192 193 /* Temporarily drop privileged uid for mkdir/bind. */ 194 temporarily_use_uid(pw); 195 196 /* Allocate a buffer for the socket name, and format the name. */ 197 auth_sock_dir = xstrdup("/tmp/ssh-XXXXXXXXXX"); 198 199 /* Create private directory for socket */ 200 if (mkdtemp(auth_sock_dir) == NULL) { 201 packet_send_debug("Agent forwarding disabled: " 202 "mkdtemp() failed: %.100s", strerror(errno)); 203 restore_uid(); 204 free(auth_sock_dir); 205 auth_sock_dir = NULL; 206 goto authsock_err; 207 } 208 209 xasprintf(&auth_sock_name, "%s/agent.%ld", 210 auth_sock_dir, (long) getpid()); 211 212 /* Start a Unix listener on auth_sock_name. */ 213 sock = unix_listener(auth_sock_name, SSH_LISTEN_BACKLOG, 0); 214 215 /* Restore the privileged uid. */ 216 restore_uid(); 217 218 /* Check for socket/bind/listen failure. */ 219 if (sock < 0) 220 goto authsock_err; 221 222 /* Allocate a channel for the authentication agent socket. */ 223 nc = channel_new("auth socket", 224 SSH_CHANNEL_AUTH_SOCKET, sock, sock, -1, 225 CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 226 0, "auth socket", 1); 227 nc->path = xstrdup(auth_sock_name); 228 return 1; 229 230 authsock_err: 231 free(auth_sock_name); 232 if (auth_sock_dir != NULL) { 233 rmdir(auth_sock_dir); 234 free(auth_sock_dir); 235 } 236 if (sock != -1) 237 close(sock); 238 auth_sock_name = NULL; 239 auth_sock_dir = NULL; 240 return 0; 241 } 242 243 static void 244 display_loginmsg(void) 245 { 246 if (buffer_len(&loginmsg) > 0) { 247 buffer_append(&loginmsg, "\0", 1); 248 printf("%s", (char *)buffer_ptr(&loginmsg)); 249 buffer_clear(&loginmsg); 250 } 251 } 252 253 void 254 do_authenticated(Authctxt *authctxt) 255 { 256 setproctitle("%s", authctxt->pw->pw_name); 257 258 /* setup the channel layer */ 259 /* XXX - streamlocal? */ 260 if (no_port_forwarding_flag || 261 (options.allow_tcp_forwarding & FORWARD_LOCAL) == 0) 262 channel_disable_adm_local_opens(); 263 else 264 channel_permit_all_opens(); 265 266 auth_debug_send(); 267 268 if (compat20) 269 do_authenticated2(authctxt); 270 else 271 do_authenticated1(authctxt); 272 273 do_cleanup(authctxt); 274 } 275 276 /* 277 * Prepares for an interactive session. This is called after the user has 278 * been successfully authenticated. During this message exchange, pseudo 279 * terminals are allocated, X11, TCP/IP, and authentication agent forwardings 280 * are requested, etc. 281 */ 282 static void 283 do_authenticated1(Authctxt *authctxt) 284 { 285 Session *s; 286 char *command; 287 int success, type, screen_flag; 288 int enable_compression_after_reply = 0; 289 u_int proto_len, data_len, dlen, compression_level = 0; 290 291 s = session_new(); 292 if (s == NULL) { 293 error("no more sessions"); 294 return; 295 } 296 s->authctxt = authctxt; 297 s->pw = authctxt->pw; 298 299 /* 300 * We stay in this loop until the client requests to execute a shell 301 * or a command. 302 */ 303 for (;;) { 304 success = 0; 305 306 /* Get a packet from the client. */ 307 type = packet_read(); 308 309 /* Process the packet. */ 310 switch (type) { 311 case SSH_CMSG_REQUEST_COMPRESSION: 312 compression_level = packet_get_int(); 313 packet_check_eom(); 314 if (compression_level < 1 || compression_level > 9) { 315 packet_send_debug("Received invalid compression level %d.", 316 compression_level); 317 break; 318 } 319 if (options.compression == COMP_NONE) { 320 debug2("compression disabled"); 321 break; 322 } 323 /* Enable compression after we have responded with SUCCESS. */ 324 enable_compression_after_reply = 1; 325 success = 1; 326 break; 327 328 case SSH_CMSG_REQUEST_PTY: 329 success = session_pty_req(s); 330 break; 331 332 case SSH_CMSG_X11_REQUEST_FORWARDING: 333 s->auth_proto = packet_get_string(&proto_len); 334 s->auth_data = packet_get_string(&data_len); 335 336 screen_flag = packet_get_protocol_flags() & 337 SSH_PROTOFLAG_SCREEN_NUMBER; 338 debug2("SSH_PROTOFLAG_SCREEN_NUMBER: %d", screen_flag); 339 340 if (packet_remaining() == 4) { 341 if (!screen_flag) 342 debug2("Buggy client: " 343 "X11 screen flag missing"); 344 s->screen = packet_get_int(); 345 } else { 346 s->screen = 0; 347 } 348 packet_check_eom(); 349 success = session_setup_x11fwd(s); 350 if (!success) { 351 free(s->auth_proto); 352 free(s->auth_data); 353 s->auth_proto = NULL; 354 s->auth_data = NULL; 355 } 356 break; 357 358 case SSH_CMSG_AGENT_REQUEST_FORWARDING: 359 if (!options.allow_agent_forwarding || 360 no_agent_forwarding_flag || compat13) { 361 debug("Authentication agent forwarding not permitted for this authentication."); 362 break; 363 } 364 debug("Received authentication agent forwarding request."); 365 success = auth_input_request_forwarding(s->pw); 366 break; 367 368 case SSH_CMSG_PORT_FORWARD_REQUEST: 369 if (no_port_forwarding_flag) { 370 debug("Port forwarding not permitted for this authentication."); 371 break; 372 } 373 if (!(options.allow_tcp_forwarding & FORWARD_REMOTE)) { 374 debug("Port forwarding not permitted."); 375 break; 376 } 377 debug("Received TCP/IP port forwarding request."); 378 if (channel_input_port_forward_request(s->pw->pw_uid == 0, 379 &options.fwd_opts) < 0) { 380 debug("Port forwarding failed."); 381 break; 382 } 383 success = 1; 384 break; 385 386 case SSH_CMSG_MAX_PACKET_SIZE: 387 if (packet_set_maxsize(packet_get_int()) > 0) 388 success = 1; 389 break; 390 391 case SSH_CMSG_EXEC_SHELL: 392 case SSH_CMSG_EXEC_CMD: 393 if (type == SSH_CMSG_EXEC_CMD) { 394 command = packet_get_string(&dlen); 395 debug("Exec command '%.500s'", command); 396 if (do_exec(s, command) != 0) 397 packet_disconnect( 398 "command execution failed"); 399 free(command); 400 } else { 401 if (do_exec(s, NULL) != 0) 402 packet_disconnect( 403 "shell execution failed"); 404 } 405 packet_check_eom(); 406 session_close(s); 407 return; 408 409 default: 410 /* 411 * Any unknown messages in this phase are ignored, 412 * and a failure message is returned. 413 */ 414 logit("Unknown packet type received after authentication: %d", type); 415 } 416 packet_start(success ? SSH_SMSG_SUCCESS : SSH_SMSG_FAILURE); 417 packet_send(); 418 packet_write_wait(); 419 420 /* Enable compression now that we have replied if appropriate. */ 421 if (enable_compression_after_reply) { 422 enable_compression_after_reply = 0; 423 packet_start_compression(compression_level); 424 } 425 } 426 } 427 428 #define USE_PIPES 1 429 /* 430 * This is called to fork and execute a command when we have no tty. This 431 * will call do_child from the child, and server_loop from the parent after 432 * setting up file descriptors and such. 433 */ 434 int 435 do_exec_no_pty(Session *s, const char *command) 436 { 437 pid_t pid; 438 439 #ifdef USE_PIPES 440 int pin[2], pout[2], perr[2]; 441 442 if (s == NULL) 443 fatal("do_exec_no_pty: no session"); 444 445 /* Allocate pipes for communicating with the program. */ 446 if (pipe(pin) < 0) { 447 error("%s: pipe in: %.100s", __func__, strerror(errno)); 448 return -1; 449 } 450 if (pipe(pout) < 0) { 451 error("%s: pipe out: %.100s", __func__, strerror(errno)); 452 close(pin[0]); 453 close(pin[1]); 454 return -1; 455 } 456 if (pipe(perr) < 0) { 457 error("%s: pipe err: %.100s", __func__, 458 strerror(errno)); 459 close(pin[0]); 460 close(pin[1]); 461 close(pout[0]); 462 close(pout[1]); 463 return -1; 464 } 465 #else 466 int inout[2], err[2]; 467 468 if (s == NULL) 469 fatal("do_exec_no_pty: no session"); 470 471 /* Uses socket pairs to communicate with the program. */ 472 if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) < 0) { 473 error("%s: socketpair #1: %.100s", __func__, strerror(errno)); 474 return -1; 475 } 476 if (socketpair(AF_UNIX, SOCK_STREAM, 0, err) < 0) { 477 error("%s: socketpair #2: %.100s", __func__, 478 strerror(errno)); 479 close(inout[0]); 480 close(inout[1]); 481 return -1; 482 } 483 #endif 484 485 session_proctitle(s); 486 487 /* Fork the child. */ 488 switch ((pid = fork())) { 489 case -1: 490 error("%s: fork: %.100s", __func__, strerror(errno)); 491 #ifdef USE_PIPES 492 close(pin[0]); 493 close(pin[1]); 494 close(pout[0]); 495 close(pout[1]); 496 close(perr[0]); 497 close(perr[1]); 498 #else 499 close(inout[0]); 500 close(inout[1]); 501 close(err[0]); 502 close(err[1]); 503 #endif 504 return -1; 505 case 0: 506 is_child = 1; 507 508 /* Child. Reinitialize the log since the pid has changed. */ 509 log_init(__progname, options.log_level, 510 options.log_facility, log_stderr); 511 512 /* 513 * Create a new session and process group since the 4.4BSD 514 * setlogin() affects the entire process group. 515 */ 516 if (setsid() < 0) 517 error("setsid failed: %.100s", strerror(errno)); 518 519 #ifdef USE_PIPES 520 /* 521 * Redirect stdin. We close the parent side of the socket 522 * pair, and make the child side the standard input. 523 */ 524 close(pin[1]); 525 if (dup2(pin[0], 0) < 0) 526 perror("dup2 stdin"); 527 close(pin[0]); 528 529 /* Redirect stdout. */ 530 close(pout[0]); 531 if (dup2(pout[1], 1) < 0) 532 perror("dup2 stdout"); 533 close(pout[1]); 534 535 /* Redirect stderr. */ 536 close(perr[0]); 537 if (dup2(perr[1], 2) < 0) 538 perror("dup2 stderr"); 539 close(perr[1]); 540 #else 541 /* 542 * Redirect stdin, stdout, and stderr. Stdin and stdout will 543 * use the same socket, as some programs (particularly rdist) 544 * seem to depend on it. 545 */ 546 close(inout[1]); 547 close(err[1]); 548 if (dup2(inout[0], 0) < 0) /* stdin */ 549 perror("dup2 stdin"); 550 if (dup2(inout[0], 1) < 0) /* stdout (same as stdin) */ 551 perror("dup2 stdout"); 552 close(inout[0]); 553 if (dup2(err[0], 2) < 0) /* stderr */ 554 perror("dup2 stderr"); 555 close(err[0]); 556 #endif 557 558 559 #ifdef _UNICOS 560 cray_init_job(s->pw); /* set up cray jid and tmpdir */ 561 #endif 562 563 /* Do processing for the child (exec command etc). */ 564 do_child(s, command); 565 /* NOTREACHED */ 566 default: 567 break; 568 } 569 570 #ifdef _UNICOS 571 signal(WJSIGNAL, cray_job_termination_handler); 572 #endif /* _UNICOS */ 573 #ifdef HAVE_CYGWIN 574 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); 575 #endif 576 577 s->pid = pid; 578 /* Set interactive/non-interactive mode. */ 579 packet_set_interactive(s->display != NULL, 580 options.ip_qos_interactive, options.ip_qos_bulk); 581 582 /* 583 * Clear loginmsg, since it's the child's responsibility to display 584 * it to the user, otherwise multiple sessions may accumulate 585 * multiple copies of the login messages. 586 */ 587 buffer_clear(&loginmsg); 588 589 #ifdef USE_PIPES 590 /* We are the parent. Close the child sides of the pipes. */ 591 close(pin[0]); 592 close(pout[1]); 593 close(perr[1]); 594 595 if (compat20) { 596 session_set_fds(s, pin[1], pout[0], perr[0], 597 s->is_subsystem, 0); 598 } else { 599 /* Enter the interactive session. */ 600 server_loop(pid, pin[1], pout[0], perr[0]); 601 /* server_loop has closed pin[1], pout[0], and perr[0]. */ 602 } 603 #else 604 /* We are the parent. Close the child sides of the socket pairs. */ 605 close(inout[0]); 606 close(err[0]); 607 608 /* 609 * Enter the interactive session. Note: server_loop must be able to 610 * handle the case that fdin and fdout are the same. 611 */ 612 if (compat20) { 613 session_set_fds(s, inout[1], inout[1], err[1], 614 s->is_subsystem, 0); 615 } else { 616 server_loop(pid, inout[1], inout[1], err[1]); 617 /* server_loop has closed inout[1] and err[1]. */ 618 } 619 #endif 620 return 0; 621 } 622 623 /* 624 * This is called to fork and execute a command when we have a tty. This 625 * will call do_child from the child, and server_loop from the parent after 626 * setting up file descriptors, controlling tty, updating wtmp, utmp, 627 * lastlog, and other such operations. 628 */ 629 int 630 do_exec_pty(Session *s, const char *command) 631 { 632 int fdout, ptyfd, ttyfd, ptymaster; 633 pid_t pid; 634 635 if (s == NULL) 636 fatal("do_exec_pty: no session"); 637 ptyfd = s->ptyfd; 638 ttyfd = s->ttyfd; 639 640 /* 641 * Create another descriptor of the pty master side for use as the 642 * standard input. We could use the original descriptor, but this 643 * simplifies code in server_loop. The descriptor is bidirectional. 644 * Do this before forking (and cleanup in the child) so as to 645 * detect and gracefully fail out-of-fd conditions. 646 */ 647 if ((fdout = dup(ptyfd)) < 0) { 648 error("%s: dup #1: %s", __func__, strerror(errno)); 649 close(ttyfd); 650 close(ptyfd); 651 return -1; 652 } 653 /* we keep a reference to the pty master */ 654 if ((ptymaster = dup(ptyfd)) < 0) { 655 error("%s: dup #2: %s", __func__, strerror(errno)); 656 close(ttyfd); 657 close(ptyfd); 658 close(fdout); 659 return -1; 660 } 661 662 /* Fork the child. */ 663 switch ((pid = fork())) { 664 case -1: 665 error("%s: fork: %.100s", __func__, strerror(errno)); 666 close(fdout); 667 close(ptymaster); 668 close(ttyfd); 669 close(ptyfd); 670 return -1; 671 case 0: 672 is_child = 1; 673 674 close(fdout); 675 close(ptymaster); 676 677 /* Child. Reinitialize the log because the pid has changed. */ 678 log_init(__progname, options.log_level, 679 options.log_facility, log_stderr); 680 /* Close the master side of the pseudo tty. */ 681 close(ptyfd); 682 683 /* Make the pseudo tty our controlling tty. */ 684 pty_make_controlling_tty(&ttyfd, s->tty); 685 686 /* Redirect stdin/stdout/stderr from the pseudo tty. */ 687 if (dup2(ttyfd, 0) < 0) 688 error("dup2 stdin: %s", strerror(errno)); 689 if (dup2(ttyfd, 1) < 0) 690 error("dup2 stdout: %s", strerror(errno)); 691 if (dup2(ttyfd, 2) < 0) 692 error("dup2 stderr: %s", strerror(errno)); 693 694 /* Close the extra descriptor for the pseudo tty. */ 695 close(ttyfd); 696 697 /* record login, etc. similar to login(1) */ 698 #ifndef HAVE_OSF_SIA 699 if (!(options.use_login && command == NULL)) { 700 #ifdef _UNICOS 701 cray_init_job(s->pw); /* set up cray jid and tmpdir */ 702 #endif /* _UNICOS */ 703 do_login(s, command); 704 } 705 # ifdef LOGIN_NEEDS_UTMPX 706 else 707 do_pre_login(s); 708 # endif 709 #endif 710 /* 711 * Do common processing for the child, such as execing 712 * the command. 713 */ 714 do_child(s, command); 715 /* NOTREACHED */ 716 default: 717 break; 718 } 719 720 #ifdef _UNICOS 721 signal(WJSIGNAL, cray_job_termination_handler); 722 #endif /* _UNICOS */ 723 #ifdef HAVE_CYGWIN 724 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); 725 #endif 726 727 s->pid = pid; 728 729 /* Parent. Close the slave side of the pseudo tty. */ 730 close(ttyfd); 731 732 /* Enter interactive session. */ 733 s->ptymaster = ptymaster; 734 packet_set_interactive(1, 735 options.ip_qos_interactive, options.ip_qos_bulk); 736 if (compat20) { 737 session_set_fds(s, ptyfd, fdout, -1, 1, 1); 738 } else { 739 server_loop(pid, ptyfd, fdout, -1); 740 /* server_loop _has_ closed ptyfd and fdout. */ 741 } 742 return 0; 743 } 744 745 #ifdef LOGIN_NEEDS_UTMPX 746 static void 747 do_pre_login(Session *s) 748 { 749 socklen_t fromlen; 750 struct sockaddr_storage from; 751 pid_t pid = getpid(); 752 753 /* 754 * Get IP address of client. If the connection is not a socket, let 755 * the address be 0.0.0.0. 756 */ 757 memset(&from, 0, sizeof(from)); 758 fromlen = sizeof(from); 759 if (packet_connection_is_on_socket()) { 760 if (getpeername(packet_get_connection_in(), 761 (struct sockaddr *)&from, &fromlen) < 0) { 762 debug("getpeername: %.100s", strerror(errno)); 763 cleanup_exit(255); 764 } 765 } 766 767 record_utmp_only(pid, s->tty, s->pw->pw_name, 768 get_remote_name_or_ip(utmp_len, options.use_dns), 769 (struct sockaddr *)&from, fromlen); 770 } 771 #endif 772 773 /* 774 * This is called to fork and execute a command. If another command is 775 * to be forced, execute that instead. 776 */ 777 int 778 do_exec(Session *s, const char *command) 779 { 780 int ret; 781 const char *forced = NULL; 782 char session_type[1024], *tty = NULL; 783 784 if (options.adm_forced_command) { 785 original_command = command; 786 command = options.adm_forced_command; 787 forced = "(config)"; 788 } else if (forced_command) { 789 original_command = command; 790 command = forced_command; 791 forced = "(key-option)"; 792 } 793 if (forced != NULL) { 794 if (IS_INTERNAL_SFTP(command)) { 795 s->is_subsystem = s->is_subsystem ? 796 SUBSYSTEM_INT_SFTP : SUBSYSTEM_INT_SFTP_ERROR; 797 } else if (s->is_subsystem) 798 s->is_subsystem = SUBSYSTEM_EXT; 799 snprintf(session_type, sizeof(session_type), 800 "forced-command %s '%.900s'", forced, command); 801 } else if (s->is_subsystem) { 802 snprintf(session_type, sizeof(session_type), 803 "subsystem '%.900s'", s->subsys); 804 } else if (command == NULL) { 805 snprintf(session_type, sizeof(session_type), "shell"); 806 } else { 807 /* NB. we don't log unforced commands to preserve privacy */ 808 snprintf(session_type, sizeof(session_type), "command"); 809 } 810 811 if (s->ttyfd != -1) { 812 tty = s->tty; 813 if (strncmp(tty, "/dev/", 5) == 0) 814 tty += 5; 815 } 816 817 verbose("Starting session: %s%s%s for %s from %.200s port %d", 818 session_type, 819 tty == NULL ? "" : " on ", 820 tty == NULL ? "" : tty, 821 s->pw->pw_name, 822 get_remote_ipaddr(), 823 get_remote_port()); 824 825 #ifdef SSH_AUDIT_EVENTS 826 if (command != NULL) 827 PRIVSEP(audit_run_command(command)); 828 else if (s->ttyfd == -1) { 829 char *shell = s->pw->pw_shell; 830 831 if (shell[0] == '\0') /* empty shell means /bin/sh */ 832 shell =_PATH_BSHELL; 833 PRIVSEP(audit_run_command(shell)); 834 } 835 #endif 836 if (s->ttyfd != -1) 837 ret = do_exec_pty(s, command); 838 else 839 ret = do_exec_no_pty(s, command); 840 841 original_command = NULL; 842 843 /* 844 * Clear loginmsg: it's the child's responsibility to display 845 * it to the user, otherwise multiple sessions may accumulate 846 * multiple copies of the login messages. 847 */ 848 buffer_clear(&loginmsg); 849 850 return ret; 851 } 852 853 /* administrative, login(1)-like work */ 854 void 855 do_login(Session *s, const char *command) 856 { 857 socklen_t fromlen; 858 struct sockaddr_storage from; 859 struct passwd * pw = s->pw; 860 pid_t pid = getpid(); 861 862 /* 863 * Get IP address of client. If the connection is not a socket, let 864 * the address be 0.0.0.0. 865 */ 866 memset(&from, 0, sizeof(from)); 867 fromlen = sizeof(from); 868 if (packet_connection_is_on_socket()) { 869 if (getpeername(packet_get_connection_in(), 870 (struct sockaddr *)&from, &fromlen) < 0) { 871 debug("getpeername: %.100s", strerror(errno)); 872 cleanup_exit(255); 873 } 874 } 875 876 /* Record that there was a login on that tty from the remote host. */ 877 if (!use_privsep) 878 record_login(pid, s->tty, pw->pw_name, pw->pw_uid, 879 get_remote_name_or_ip(utmp_len, 880 options.use_dns), 881 (struct sockaddr *)&from, fromlen); 882 883 #ifdef USE_PAM 884 /* 885 * If password change is needed, do it now. 886 * This needs to occur before the ~/.hushlogin check. 887 */ 888 if (options.use_pam && !use_privsep && s->authctxt->force_pwchange) { 889 display_loginmsg(); 890 do_pam_chauthtok(); 891 s->authctxt->force_pwchange = 0; 892 /* XXX - signal [net] parent to enable forwardings */ 893 } 894 #endif 895 896 if (check_quietlogin(s, command)) 897 return; 898 899 display_loginmsg(); 900 901 do_motd(); 902 } 903 904 /* 905 * Display the message of the day. 906 */ 907 void 908 do_motd(void) 909 { 910 FILE *f; 911 char buf[256]; 912 913 if (options.print_motd) { 914 #ifdef HAVE_LOGIN_CAP 915 f = fopen(login_getcapstr(lc, "welcome", "/etc/motd", 916 "/etc/motd"), "r"); 917 #else 918 f = fopen("/etc/motd", "r"); 919 #endif 920 if (f) { 921 while (fgets(buf, sizeof(buf), f)) 922 fputs(buf, stdout); 923 fclose(f); 924 } 925 } 926 } 927 928 929 /* 930 * Check for quiet login, either .hushlogin or command given. 931 */ 932 int 933 check_quietlogin(Session *s, const char *command) 934 { 935 char buf[256]; 936 struct passwd *pw = s->pw; 937 struct stat st; 938 939 /* Return 1 if .hushlogin exists or a command given. */ 940 if (command != NULL) 941 return 1; 942 snprintf(buf, sizeof(buf), "%.200s/.hushlogin", pw->pw_dir); 943 #ifdef HAVE_LOGIN_CAP 944 if (login_getcapbool(lc, "hushlogin", 0) || stat(buf, &st) >= 0) 945 return 1; 946 #else 947 if (stat(buf, &st) >= 0) 948 return 1; 949 #endif 950 return 0; 951 } 952 953 /* 954 * Sets the value of the given variable in the environment. If the variable 955 * already exists, its value is overridden. 956 */ 957 void 958 child_set_env(char ***envp, u_int *envsizep, const char *name, 959 const char *value) 960 { 961 char **env; 962 u_int envsize; 963 u_int i, namelen; 964 965 if (strchr(name, '=') != NULL) { 966 error("Invalid environment variable \"%.100s\"", name); 967 return; 968 } 969 970 /* 971 * If we're passed an uninitialized list, allocate a single null 972 * entry before continuing. 973 */ 974 if (*envp == NULL && *envsizep == 0) { 975 *envp = xmalloc(sizeof(char *)); 976 *envp[0] = NULL; 977 *envsizep = 1; 978 } 979 980 /* 981 * Find the slot where the value should be stored. If the variable 982 * already exists, we reuse the slot; otherwise we append a new slot 983 * at the end of the array, expanding if necessary. 984 */ 985 env = *envp; 986 namelen = strlen(name); 987 for (i = 0; env[i]; i++) 988 if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=') 989 break; 990 if (env[i]) { 991 /* Reuse the slot. */ 992 free(env[i]); 993 } else { 994 /* New variable. Expand if necessary. */ 995 envsize = *envsizep; 996 if (i >= envsize - 1) { 997 if (envsize >= 1000) 998 fatal("child_set_env: too many env vars"); 999 envsize += 50; 1000 env = (*envp) = xrealloc(env, envsize, sizeof(char *)); 1001 *envsizep = envsize; 1002 } 1003 /* Need to set the NULL pointer at end of array beyond the new slot. */ 1004 env[i + 1] = NULL; 1005 } 1006 1007 /* Allocate space and format the variable in the appropriate slot. */ 1008 env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1); 1009 snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value); 1010 } 1011 1012 /* 1013 * Reads environment variables from the given file and adds/overrides them 1014 * into the environment. If the file does not exist, this does nothing. 1015 * Otherwise, it must consist of empty lines, comments (line starts with '#') 1016 * and assignments of the form name=value. No other forms are allowed. 1017 */ 1018 static void 1019 read_environment_file(char ***env, u_int *envsize, 1020 const char *filename) 1021 { 1022 FILE *f; 1023 char buf[4096]; 1024 char *cp, *value; 1025 u_int lineno = 0; 1026 1027 f = fopen(filename, "r"); 1028 if (!f) 1029 return; 1030 1031 while (fgets(buf, sizeof(buf), f)) { 1032 if (++lineno > 1000) 1033 fatal("Too many lines in environment file %s", filename); 1034 for (cp = buf; *cp == ' ' || *cp == '\t'; cp++) 1035 ; 1036 if (!*cp || *cp == '#' || *cp == '\n') 1037 continue; 1038 1039 cp[strcspn(cp, "\n")] = '\0'; 1040 1041 value = strchr(cp, '='); 1042 if (value == NULL) { 1043 fprintf(stderr, "Bad line %u in %.100s\n", lineno, 1044 filename); 1045 continue; 1046 } 1047 /* 1048 * Replace the equals sign by nul, and advance value to 1049 * the value string. 1050 */ 1051 *value = '\0'; 1052 value++; 1053 child_set_env(env, envsize, cp, value); 1054 } 1055 fclose(f); 1056 } 1057 1058 #ifdef HAVE_ETC_DEFAULT_LOGIN 1059 /* 1060 * Return named variable from specified environment, or NULL if not present. 1061 */ 1062 static char * 1063 child_get_env(char **env, const char *name) 1064 { 1065 int i; 1066 size_t len; 1067 1068 len = strlen(name); 1069 for (i=0; env[i] != NULL; i++) 1070 if (strncmp(name, env[i], len) == 0 && env[i][len] == '=') 1071 return(env[i] + len + 1); 1072 return NULL; 1073 } 1074 1075 /* 1076 * Read /etc/default/login. 1077 * We pick up the PATH (or SUPATH for root) and UMASK. 1078 */ 1079 static void 1080 read_etc_default_login(char ***env, u_int *envsize, uid_t uid) 1081 { 1082 char **tmpenv = NULL, *var; 1083 u_int i, tmpenvsize = 0; 1084 u_long mask; 1085 1086 /* 1087 * We don't want to copy the whole file to the child's environment, 1088 * so we use a temporary environment and copy the variables we're 1089 * interested in. 1090 */ 1091 read_environment_file(&tmpenv, &tmpenvsize, "/etc/default/login"); 1092 1093 if (tmpenv == NULL) 1094 return; 1095 1096 if (uid == 0) 1097 var = child_get_env(tmpenv, "SUPATH"); 1098 else 1099 var = child_get_env(tmpenv, "PATH"); 1100 if (var != NULL) 1101 child_set_env(env, envsize, "PATH", var); 1102 1103 if ((var = child_get_env(tmpenv, "UMASK")) != NULL) 1104 if (sscanf(var, "%5lo", &mask) == 1) 1105 umask((mode_t)mask); 1106 1107 for (i = 0; tmpenv[i] != NULL; i++) 1108 free(tmpenv[i]); 1109 free(tmpenv); 1110 } 1111 #endif /* HAVE_ETC_DEFAULT_LOGIN */ 1112 1113 void 1114 copy_environment(char **source, char ***env, u_int *envsize) 1115 { 1116 char *var_name, *var_val; 1117 int i; 1118 1119 if (source == NULL) 1120 return; 1121 1122 for(i = 0; source[i] != NULL; i++) { 1123 var_name = xstrdup(source[i]); 1124 if ((var_val = strstr(var_name, "=")) == NULL) { 1125 free(var_name); 1126 continue; 1127 } 1128 *var_val++ = '\0'; 1129 1130 debug3("Copy environment: %s=%s", var_name, var_val); 1131 child_set_env(env, envsize, var_name, var_val); 1132 1133 free(var_name); 1134 } 1135 } 1136 1137 static char ** 1138 do_setup_env(Session *s, const char *shell) 1139 { 1140 char buf[256]; 1141 u_int i, envsize; 1142 char **env, *laddr; 1143 struct passwd *pw = s->pw; 1144 #if !defined (HAVE_LOGIN_CAP) && !defined (HAVE_CYGWIN) 1145 char *path = NULL; 1146 #endif 1147 1148 /* Initialize the environment. */ 1149 envsize = 100; 1150 env = xcalloc(envsize, sizeof(char *)); 1151 env[0] = NULL; 1152 1153 #ifdef HAVE_CYGWIN 1154 /* 1155 * The Windows environment contains some setting which are 1156 * important for a running system. They must not be dropped. 1157 */ 1158 { 1159 char **p; 1160 1161 p = fetch_windows_environment(); 1162 copy_environment(p, &env, &envsize); 1163 free_windows_environment(p); 1164 } 1165 #endif 1166 1167 #ifdef GSSAPI 1168 /* Allow any GSSAPI methods that we've used to alter 1169 * the childs environment as they see fit 1170 */ 1171 ssh_gssapi_do_child(&env, &envsize); 1172 #endif 1173 1174 if (!options.use_login) { 1175 /* Set basic environment. */ 1176 for (i = 0; i < s->num_env; i++) 1177 child_set_env(&env, &envsize, s->env[i].name, 1178 s->env[i].val); 1179 1180 child_set_env(&env, &envsize, "USER", pw->pw_name); 1181 child_set_env(&env, &envsize, "LOGNAME", pw->pw_name); 1182 #ifdef _AIX 1183 child_set_env(&env, &envsize, "LOGIN", pw->pw_name); 1184 #endif 1185 child_set_env(&env, &envsize, "HOME", pw->pw_dir); 1186 #ifdef HAVE_LOGIN_CAP 1187 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETPATH) < 0) 1188 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); 1189 else 1190 child_set_env(&env, &envsize, "PATH", getenv("PATH")); 1191 #else /* HAVE_LOGIN_CAP */ 1192 # ifndef HAVE_CYGWIN 1193 /* 1194 * There's no standard path on Windows. The path contains 1195 * important components pointing to the system directories, 1196 * needed for loading shared libraries. So the path better 1197 * remains intact here. 1198 */ 1199 # ifdef HAVE_ETC_DEFAULT_LOGIN 1200 read_etc_default_login(&env, &envsize, pw->pw_uid); 1201 path = child_get_env(env, "PATH"); 1202 # endif /* HAVE_ETC_DEFAULT_LOGIN */ 1203 if (path == NULL || *path == '\0') { 1204 child_set_env(&env, &envsize, "PATH", 1205 s->pw->pw_uid == 0 ? 1206 SUPERUSER_PATH : _PATH_STDPATH); 1207 } 1208 # endif /* HAVE_CYGWIN */ 1209 #endif /* HAVE_LOGIN_CAP */ 1210 1211 #ifndef ANDROID 1212 snprintf(buf, sizeof buf, "%.200s/%.50s", 1213 _PATH_MAILDIR, pw->pw_name); 1214 child_set_env(&env, &envsize, "MAIL", buf); 1215 #endif 1216 1217 /* Normal systems set SHELL by default. */ 1218 child_set_env(&env, &envsize, "SHELL", shell); 1219 } 1220 if (getenv("TZ")) 1221 child_set_env(&env, &envsize, "TZ", getenv("TZ")); 1222 1223 /* Set custom environment options from RSA authentication. */ 1224 if (!options.use_login) { 1225 while (custom_environment) { 1226 struct envstring *ce = custom_environment; 1227 char *str = ce->s; 1228 1229 for (i = 0; str[i] != '=' && str[i]; i++) 1230 ; 1231 if (str[i] == '=') { 1232 str[i] = 0; 1233 child_set_env(&env, &envsize, str, str + i + 1); 1234 } 1235 custom_environment = ce->next; 1236 free(ce->s); 1237 free(ce); 1238 } 1239 } 1240 1241 /* SSH_CLIENT deprecated */ 1242 snprintf(buf, sizeof buf, "%.50s %d %d", 1243 get_remote_ipaddr(), get_remote_port(), get_local_port()); 1244 child_set_env(&env, &envsize, "SSH_CLIENT", buf); 1245 1246 laddr = get_local_ipaddr(packet_get_connection_in()); 1247 snprintf(buf, sizeof buf, "%.50s %d %.50s %d", 1248 get_remote_ipaddr(), get_remote_port(), laddr, get_local_port()); 1249 free(laddr); 1250 child_set_env(&env, &envsize, "SSH_CONNECTION", buf); 1251 1252 if (s->ttyfd != -1) 1253 child_set_env(&env, &envsize, "SSH_TTY", s->tty); 1254 if (s->term) 1255 child_set_env(&env, &envsize, "TERM", s->term); 1256 if (s->display) 1257 child_set_env(&env, &envsize, "DISPLAY", s->display); 1258 if (original_command) 1259 child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND", 1260 original_command); 1261 1262 #ifdef _UNICOS 1263 if (cray_tmpdir[0] != '\0') 1264 child_set_env(&env, &envsize, "TMPDIR", cray_tmpdir); 1265 #endif /* _UNICOS */ 1266 1267 /* 1268 * Since we clear KRB5CCNAME at startup, if it's set now then it 1269 * must have been set by a native authentication method (eg AIX or 1270 * SIA), so copy it to the child. 1271 */ 1272 { 1273 char *cp; 1274 1275 if ((cp = getenv("KRB5CCNAME")) != NULL) 1276 child_set_env(&env, &envsize, "KRB5CCNAME", cp); 1277 } 1278 1279 #ifdef _AIX 1280 { 1281 char *cp; 1282 1283 if ((cp = getenv("AUTHSTATE")) != NULL) 1284 child_set_env(&env, &envsize, "AUTHSTATE", cp); 1285 read_environment_file(&env, &envsize, "/etc/environment"); 1286 } 1287 #endif 1288 #ifdef KRB5 1289 if (s->authctxt->krb5_ccname) 1290 child_set_env(&env, &envsize, "KRB5CCNAME", 1291 s->authctxt->krb5_ccname); 1292 #endif 1293 #ifdef USE_PAM 1294 /* 1295 * Pull in any environment variables that may have 1296 * been set by PAM. 1297 */ 1298 if (options.use_pam) { 1299 char **p; 1300 1301 p = fetch_pam_child_environment(); 1302 copy_environment(p, &env, &envsize); 1303 free_pam_environment(p); 1304 1305 p = fetch_pam_environment(); 1306 copy_environment(p, &env, &envsize); 1307 free_pam_environment(p); 1308 } 1309 #endif /* USE_PAM */ 1310 1311 if (auth_sock_name != NULL) 1312 child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME, 1313 auth_sock_name); 1314 1315 /* read $HOME/.ssh/environment. */ 1316 if (options.permit_user_env && !options.use_login) { 1317 snprintf(buf, sizeof buf, "%.200s/.ssh/environment", 1318 strcmp(pw->pw_dir, "/") ? pw->pw_dir : ""); 1319 read_environment_file(&env, &envsize, buf); 1320 } 1321 if (debug_flag) { 1322 /* dump the environment */ 1323 fprintf(stderr, "Environment:\n"); 1324 for (i = 0; env[i]; i++) 1325 fprintf(stderr, " %.200s\n", env[i]); 1326 } 1327 return env; 1328 } 1329 1330 /* 1331 * Run $HOME/.ssh/rc, /etc/ssh/sshrc, or xauth (whichever is found 1332 * first in this order). 1333 */ 1334 static void 1335 do_rc_files(Session *s, const char *shell) 1336 { 1337 FILE *f = NULL; 1338 char cmd[1024]; 1339 int do_xauth; 1340 struct stat st; 1341 1342 do_xauth = 1343 s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL; 1344 1345 /* ignore _PATH_SSH_USER_RC for subsystems and admin forced commands */ 1346 if (!s->is_subsystem && options.adm_forced_command == NULL && 1347 !no_user_rc && options.permit_user_rc && 1348 stat(_PATH_SSH_USER_RC, &st) >= 0) { 1349 snprintf(cmd, sizeof cmd, "%s -c '%s %s'", 1350 shell, _PATH_BSHELL, _PATH_SSH_USER_RC); 1351 if (debug_flag) 1352 fprintf(stderr, "Running %s\n", cmd); 1353 f = popen(cmd, "w"); 1354 if (f) { 1355 if (do_xauth) 1356 fprintf(f, "%s %s\n", s->auth_proto, 1357 s->auth_data); 1358 pclose(f); 1359 } else 1360 fprintf(stderr, "Could not run %s\n", 1361 _PATH_SSH_USER_RC); 1362 } else if (stat(_PATH_SSH_SYSTEM_RC, &st) >= 0) { 1363 if (debug_flag) 1364 fprintf(stderr, "Running %s %s\n", _PATH_BSHELL, 1365 _PATH_SSH_SYSTEM_RC); 1366 f = popen(_PATH_BSHELL " " _PATH_SSH_SYSTEM_RC, "w"); 1367 if (f) { 1368 if (do_xauth) 1369 fprintf(f, "%s %s\n", s->auth_proto, 1370 s->auth_data); 1371 pclose(f); 1372 } else 1373 fprintf(stderr, "Could not run %s\n", 1374 _PATH_SSH_SYSTEM_RC); 1375 } else if (do_xauth && options.xauth_location != NULL) { 1376 /* Add authority data to .Xauthority if appropriate. */ 1377 if (debug_flag) { 1378 fprintf(stderr, 1379 "Running %.500s remove %.100s\n", 1380 options.xauth_location, s->auth_display); 1381 fprintf(stderr, 1382 "%.500s add %.100s %.100s %.100s\n", 1383 options.xauth_location, s->auth_display, 1384 s->auth_proto, s->auth_data); 1385 } 1386 snprintf(cmd, sizeof cmd, "%s -q -", 1387 options.xauth_location); 1388 f = popen(cmd, "w"); 1389 if (f) { 1390 fprintf(f, "remove %s\n", 1391 s->auth_display); 1392 fprintf(f, "add %s %s %s\n", 1393 s->auth_display, s->auth_proto, 1394 s->auth_data); 1395 pclose(f); 1396 } else { 1397 fprintf(stderr, "Could not run %s\n", 1398 cmd); 1399 } 1400 } 1401 } 1402 1403 static void 1404 do_nologin(struct passwd *pw) 1405 { 1406 FILE *f = NULL; 1407 char buf[1024], *nl, *def_nl = _PATH_NOLOGIN; 1408 struct stat sb; 1409 1410 #ifdef HAVE_LOGIN_CAP 1411 if (login_getcapbool(lc, "ignorenologin", 0) || pw->pw_uid == 0) 1412 return; 1413 nl = login_getcapstr(lc, "nologin", def_nl, def_nl); 1414 #else 1415 if (pw->pw_uid == 0) 1416 return; 1417 nl = def_nl; 1418 #endif 1419 if (stat(nl, &sb) == -1) { 1420 if (nl != def_nl) 1421 free(nl); 1422 return; 1423 } 1424 1425 /* /etc/nologin exists. Print its contents if we can and exit. */ 1426 logit("User %.100s not allowed because %s exists", pw->pw_name, nl); 1427 if ((f = fopen(nl, "r")) != NULL) { 1428 while (fgets(buf, sizeof(buf), f)) 1429 fputs(buf, stderr); 1430 fclose(f); 1431 } 1432 exit(254); 1433 } 1434 1435 /* 1436 * Chroot into a directory after checking it for safety: all path components 1437 * must be root-owned directories with strict permissions. 1438 */ 1439 static void 1440 safely_chroot(const char *path, uid_t uid) 1441 { 1442 const char *cp; 1443 char component[PATH_MAX]; 1444 struct stat st; 1445 1446 if (*path != '/') 1447 fatal("chroot path does not begin at root"); 1448 if (strlen(path) >= sizeof(component)) 1449 fatal("chroot path too long"); 1450 1451 /* 1452 * Descend the path, checking that each component is a 1453 * root-owned directory with strict permissions. 1454 */ 1455 for (cp = path; cp != NULL;) { 1456 if ((cp = strchr(cp, '/')) == NULL) 1457 strlcpy(component, path, sizeof(component)); 1458 else { 1459 cp++; 1460 memcpy(component, path, cp - path); 1461 component[cp - path] = '\0'; 1462 } 1463 1464 debug3("%s: checking '%s'", __func__, component); 1465 1466 if (stat(component, &st) != 0) 1467 fatal("%s: stat(\"%s\"): %s", __func__, 1468 component, strerror(errno)); 1469 if (st.st_uid != 0 || (st.st_mode & 022) != 0) 1470 fatal("bad ownership or modes for chroot " 1471 "directory %s\"%s\"", 1472 cp == NULL ? "" : "component ", component); 1473 if (!S_ISDIR(st.st_mode)) 1474 fatal("chroot path %s\"%s\" is not a directory", 1475 cp == NULL ? "" : "component ", component); 1476 1477 } 1478 1479 if (chdir(path) == -1) 1480 fatal("Unable to chdir to chroot path \"%s\": " 1481 "%s", path, strerror(errno)); 1482 if (chroot(path) == -1) 1483 fatal("chroot(\"%s\"): %s", path, strerror(errno)); 1484 if (chdir("/") == -1) 1485 fatal("%s: chdir(/) after chroot: %s", 1486 __func__, strerror(errno)); 1487 verbose("Changed root directory to \"%s\"", path); 1488 } 1489 1490 /* Set login name, uid, gid, and groups. */ 1491 void 1492 do_setusercontext(struct passwd *pw) 1493 { 1494 char *chroot_path, *tmp; 1495 #ifdef USE_LIBIAF 1496 int doing_chroot = 0; 1497 #endif 1498 1499 platform_setusercontext(pw); 1500 1501 if (platform_privileged_uidswap()) { 1502 #ifdef HAVE_LOGIN_CAP 1503 if (setusercontext(lc, pw, pw->pw_uid, 1504 (LOGIN_SETALL & ~(LOGIN_SETPATH|LOGIN_SETUSER))) < 0) { 1505 perror("unable to set user context"); 1506 exit(1); 1507 } 1508 #else 1509 if (setlogin(pw->pw_name) < 0) 1510 error("setlogin failed: %s", strerror(errno)); 1511 if (setgid(pw->pw_gid) < 0) { 1512 perror("setgid"); 1513 exit(1); 1514 } 1515 /* Initialize the group list. */ 1516 if (initgroups(pw->pw_name, pw->pw_gid) < 0) { 1517 perror("initgroups"); 1518 exit(1); 1519 } 1520 #if !defined(ANDROID) 1521 endgrent(); 1522 #endif 1523 #endif 1524 1525 platform_setusercontext_post_groups(pw); 1526 1527 if (options.chroot_directory != NULL && 1528 strcasecmp(options.chroot_directory, "none") != 0) { 1529 tmp = tilde_expand_filename(options.chroot_directory, 1530 pw->pw_uid); 1531 chroot_path = percent_expand(tmp, "h", pw->pw_dir, 1532 "u", pw->pw_name, (char *)NULL); 1533 safely_chroot(chroot_path, pw->pw_uid); 1534 free(tmp); 1535 free(chroot_path); 1536 /* Make sure we don't attempt to chroot again */ 1537 free(options.chroot_directory); 1538 options.chroot_directory = NULL; 1539 #ifdef USE_LIBIAF 1540 doing_chroot = 1; 1541 #endif 1542 } 1543 1544 #ifdef HAVE_LOGIN_CAP 1545 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUSER) < 0) { 1546 perror("unable to set user context (setuser)"); 1547 exit(1); 1548 } 1549 /* 1550 * FreeBSD's setusercontext() will not apply the user's 1551 * own umask setting unless running with the user's UID. 1552 */ 1553 (void) setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUMASK); 1554 #else 1555 # ifdef USE_LIBIAF 1556 /* In a chroot environment, the set_id() will always fail; typically 1557 * because of the lack of necessary authentication services and runtime 1558 * such as ./usr/lib/libiaf.so, ./usr/lib/libpam.so.1, and ./etc/passwd 1559 * We skip it in the internal sftp chroot case. 1560 * We'll lose auditing and ACLs but permanently_set_uid will 1561 * take care of the rest. 1562 */ 1563 if ((doing_chroot == 0) && set_id(pw->pw_name) != 0) { 1564 fatal("set_id(%s) Failed", pw->pw_name); 1565 } 1566 # endif /* USE_LIBIAF */ 1567 /* Permanently switch to the desired uid. */ 1568 permanently_set_uid(pw); 1569 #endif 1570 } else if (options.chroot_directory != NULL && 1571 strcasecmp(options.chroot_directory, "none") != 0) { 1572 fatal("server lacks privileges to chroot to ChrootDirectory"); 1573 } 1574 1575 if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) 1576 fatal("Failed to set uids to %u.", (u_int) pw->pw_uid); 1577 } 1578 1579 static void 1580 do_pwchange(Session *s) 1581 { 1582 fflush(NULL); 1583 fprintf(stderr, "WARNING: Your password has expired.\n"); 1584 if (s->ttyfd != -1) { 1585 fprintf(stderr, 1586 "You must change your password now and login again!\n"); 1587 #ifdef WITH_SELINUX 1588 setexeccon(NULL); 1589 #endif 1590 #ifdef PASSWD_NEEDS_USERNAME 1591 execl(_PATH_PASSWD_PROG, "passwd", s->pw->pw_name, 1592 (char *)NULL); 1593 #else 1594 execl(_PATH_PASSWD_PROG, "passwd", (char *)NULL); 1595 #endif 1596 perror("passwd"); 1597 } else { 1598 fprintf(stderr, 1599 "Password change required but no TTY available.\n"); 1600 } 1601 exit(1); 1602 } 1603 1604 static void 1605 launch_login(struct passwd *pw, const char *hostname) 1606 { 1607 /* Launch login(1). */ 1608 1609 execl(LOGIN_PROGRAM, "login", "-h", hostname, 1610 #ifdef xxxLOGIN_NEEDS_TERM 1611 (s->term ? s->term : "unknown"), 1612 #endif /* LOGIN_NEEDS_TERM */ 1613 #ifdef LOGIN_NO_ENDOPT 1614 "-p", "-f", pw->pw_name, (char *)NULL); 1615 #else 1616 "-p", "-f", "--", pw->pw_name, (char *)NULL); 1617 #endif 1618 1619 /* Login couldn't be executed, die. */ 1620 1621 perror("login"); 1622 exit(1); 1623 } 1624 1625 static void 1626 child_close_fds(void) 1627 { 1628 extern int auth_sock; 1629 1630 if (auth_sock != -1) { 1631 close(auth_sock); 1632 auth_sock = -1; 1633 } 1634 1635 if (packet_get_connection_in() == packet_get_connection_out()) 1636 close(packet_get_connection_in()); 1637 else { 1638 close(packet_get_connection_in()); 1639 close(packet_get_connection_out()); 1640 } 1641 /* 1642 * Close all descriptors related to channels. They will still remain 1643 * open in the parent. 1644 */ 1645 /* XXX better use close-on-exec? -markus */ 1646 channel_close_all(); 1647 1648 #if !defined(ANDROID) 1649 /* 1650 * Close any extra file descriptors. Note that there may still be 1651 * descriptors left by system functions. They will be closed later. 1652 */ 1653 endpwent(); 1654 #endif 1655 1656 /* 1657 * Close any extra open file descriptors so that we don't have them 1658 * hanging around in clients. Note that we want to do this after 1659 * initgroups, because at least on Solaris 2.3 it leaves file 1660 * descriptors open. 1661 */ 1662 closefrom(STDERR_FILENO + 1); 1663 } 1664 1665 /* 1666 * Performs common processing for the child, such as setting up the 1667 * environment, closing extra file descriptors, setting the user and group 1668 * ids, and executing the command or shell. 1669 */ 1670 #define ARGV_MAX 10 1671 void 1672 do_child(Session *s, const char *command) 1673 { 1674 extern char **environ; 1675 char **env; 1676 char *argv[ARGV_MAX]; 1677 const char *shell, *shell0, *hostname = NULL; 1678 struct passwd *pw = s->pw; 1679 int r = 0; 1680 1681 /* remove hostkey from the child's memory */ 1682 destroy_sensitive_data(); 1683 1684 /* Force a password change */ 1685 if (s->authctxt->force_pwchange) { 1686 do_setusercontext(pw); 1687 child_close_fds(); 1688 do_pwchange(s); 1689 exit(1); 1690 } 1691 1692 /* login(1) is only called if we execute the login shell */ 1693 if (options.use_login && command != NULL) 1694 options.use_login = 0; 1695 1696 #ifdef _UNICOS 1697 cray_setup(pw->pw_uid, pw->pw_name, command); 1698 #endif /* _UNICOS */ 1699 1700 /* 1701 * Login(1) does this as well, and it needs uid 0 for the "-h" 1702 * switch, so we let login(1) to this for us. 1703 */ 1704 if (!options.use_login) { 1705 #ifdef HAVE_OSF_SIA 1706 session_setup_sia(pw, s->ttyfd == -1 ? NULL : s->tty); 1707 if (!check_quietlogin(s, command)) 1708 do_motd(); 1709 #else /* HAVE_OSF_SIA */ 1710 /* When PAM is enabled we rely on it to do the nologin check */ 1711 if (!options.use_pam) 1712 do_nologin(pw); 1713 do_setusercontext(pw); 1714 /* 1715 * PAM session modules in do_setusercontext may have 1716 * generated messages, so if this in an interactive 1717 * login then display them too. 1718 */ 1719 if (!check_quietlogin(s, command)) 1720 display_loginmsg(); 1721 #endif /* HAVE_OSF_SIA */ 1722 } 1723 1724 #ifdef USE_PAM 1725 if (options.use_pam && !options.use_login && !is_pam_session_open()) { 1726 debug3("PAM session not opened, exiting"); 1727 display_loginmsg(); 1728 exit(254); 1729 } 1730 #endif 1731 1732 /* 1733 * Get the shell from the password data. An empty shell field is 1734 * legal, and means /bin/sh. 1735 */ 1736 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; 1737 1738 /* 1739 * Make sure $SHELL points to the shell from the password file, 1740 * even if shell is overridden from login.conf 1741 */ 1742 env = do_setup_env(s, shell); 1743 1744 #ifdef HAVE_LOGIN_CAP 1745 shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell); 1746 #endif 1747 1748 /* we have to stash the hostname before we close our socket. */ 1749 if (options.use_login) 1750 hostname = get_remote_name_or_ip(utmp_len, 1751 options.use_dns); 1752 /* 1753 * Close the connection descriptors; note that this is the child, and 1754 * the server will still have the socket open, and it is important 1755 * that we do not shutdown it. Note that the descriptors cannot be 1756 * closed before building the environment, as we call 1757 * get_remote_ipaddr there. 1758 */ 1759 child_close_fds(); 1760 1761 /* 1762 * Must take new environment into use so that .ssh/rc, 1763 * /etc/ssh/sshrc and xauth are run in the proper environment. 1764 */ 1765 environ = env; 1766 1767 #if defined(KRB5) && defined(USE_AFS) 1768 /* 1769 * At this point, we check to see if AFS is active and if we have 1770 * a valid Kerberos 5 TGT. If so, it seems like a good idea to see 1771 * if we can (and need to) extend the ticket into an AFS token. If 1772 * we don't do this, we run into potential problems if the user's 1773 * home directory is in AFS and it's not world-readable. 1774 */ 1775 1776 if (options.kerberos_get_afs_token && k_hasafs() && 1777 (s->authctxt->krb5_ctx != NULL)) { 1778 char cell[64]; 1779 1780 debug("Getting AFS token"); 1781 1782 k_setpag(); 1783 1784 if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0) 1785 krb5_afslog(s->authctxt->krb5_ctx, 1786 s->authctxt->krb5_fwd_ccache, cell, NULL); 1787 1788 krb5_afslog_home(s->authctxt->krb5_ctx, 1789 s->authctxt->krb5_fwd_ccache, NULL, NULL, pw->pw_dir); 1790 } 1791 #endif 1792 1793 /* Change current directory to the user's home directory. */ 1794 if (chdir(pw->pw_dir) < 0) { 1795 /* Suppress missing homedir warning for chroot case */ 1796 #ifdef HAVE_LOGIN_CAP 1797 r = login_getcapbool(lc, "requirehome", 0); 1798 #endif 1799 if (r || options.chroot_directory == NULL || 1800 strcasecmp(options.chroot_directory, "none") == 0) 1801 fprintf(stderr, "Could not chdir to home " 1802 "directory %s: %s\n", pw->pw_dir, 1803 strerror(errno)); 1804 if (r) 1805 exit(1); 1806 } 1807 1808 closefrom(STDERR_FILENO + 1); 1809 1810 if (!options.use_login) 1811 do_rc_files(s, shell); 1812 1813 /* restore SIGPIPE for child */ 1814 signal(SIGPIPE, SIG_DFL); 1815 1816 if (s->is_subsystem == SUBSYSTEM_INT_SFTP_ERROR) { 1817 printf("This service allows sftp connections only.\n"); 1818 fflush(NULL); 1819 exit(1); 1820 } else if (s->is_subsystem == SUBSYSTEM_INT_SFTP) { 1821 extern int optind, optreset; 1822 int i; 1823 char *p, *args; 1824 1825 setproctitle("%s@%s", s->pw->pw_name, INTERNAL_SFTP_NAME); 1826 args = xstrdup(command ? command : "sftp-server"); 1827 for (i = 0, (p = strtok(args, " ")); p; (p = strtok(NULL, " "))) 1828 if (i < ARGV_MAX - 1) 1829 argv[i++] = p; 1830 argv[i] = NULL; 1831 optind = optreset = 1; 1832 __progname = argv[0]; 1833 #ifdef WITH_SELINUX 1834 ssh_selinux_change_context("sftpd_t"); 1835 #endif 1836 exit(sftp_server_main(i, argv, s->pw)); 1837 } 1838 1839 fflush(NULL); 1840 1841 if (options.use_login) { 1842 launch_login(pw, hostname); 1843 /* NEVERREACHED */ 1844 } 1845 1846 /* Get the last component of the shell name. */ 1847 if ((shell0 = strrchr(shell, '/')) != NULL) 1848 shell0++; 1849 else 1850 shell0 = shell; 1851 1852 /* 1853 * If we have no command, execute the shell. In this case, the shell 1854 * name to be passed in argv[0] is preceded by '-' to indicate that 1855 * this is a login shell. 1856 */ 1857 if (!command) { 1858 char argv0[256]; 1859 1860 /* Start the shell. Set initial character to '-'. */ 1861 argv0[0] = '-'; 1862 1863 if (strlcpy(argv0 + 1, shell0, sizeof(argv0) - 1) 1864 >= sizeof(argv0) - 1) { 1865 errno = EINVAL; 1866 perror(shell); 1867 exit(1); 1868 } 1869 1870 /* Execute the shell. */ 1871 argv[0] = argv0; 1872 argv[1] = NULL; 1873 execve(shell, argv, env); 1874 1875 /* Executing the shell failed. */ 1876 perror(shell); 1877 exit(1); 1878 } 1879 /* 1880 * Execute the command using the user's shell. This uses the -c 1881 * option to execute the command. 1882 */ 1883 argv[0] = (char *) shell0; 1884 argv[1] = "-c"; 1885 argv[2] = (char *) command; 1886 argv[3] = NULL; 1887 execve(shell, argv, env); 1888 perror(shell); 1889 exit(1); 1890 } 1891 1892 void 1893 session_unused(int id) 1894 { 1895 debug3("%s: session id %d unused", __func__, id); 1896 if (id >= options.max_sessions || 1897 id >= sessions_nalloc) { 1898 fatal("%s: insane session id %d (max %d nalloc %d)", 1899 __func__, id, options.max_sessions, sessions_nalloc); 1900 } 1901 memset(&sessions[id], 0, sizeof(*sessions)); 1902 sessions[id].self = id; 1903 sessions[id].used = 0; 1904 sessions[id].chanid = -1; 1905 sessions[id].ptyfd = -1; 1906 sessions[id].ttyfd = -1; 1907 sessions[id].ptymaster = -1; 1908 sessions[id].x11_chanids = NULL; 1909 sessions[id].next_unused = sessions_first_unused; 1910 sessions_first_unused = id; 1911 } 1912 1913 Session * 1914 session_new(void) 1915 { 1916 Session *s, *tmp; 1917 1918 if (sessions_first_unused == -1) { 1919 if (sessions_nalloc >= options.max_sessions) 1920 return NULL; 1921 debug2("%s: allocate (allocated %d max %d)", 1922 __func__, sessions_nalloc, options.max_sessions); 1923 tmp = xrealloc(sessions, sessions_nalloc + 1, 1924 sizeof(*sessions)); 1925 if (tmp == NULL) { 1926 error("%s: cannot allocate %d sessions", 1927 __func__, sessions_nalloc + 1); 1928 return NULL; 1929 } 1930 sessions = tmp; 1931 session_unused(sessions_nalloc++); 1932 } 1933 1934 if (sessions_first_unused >= sessions_nalloc || 1935 sessions_first_unused < 0) { 1936 fatal("%s: insane first_unused %d max %d nalloc %d", 1937 __func__, sessions_first_unused, options.max_sessions, 1938 sessions_nalloc); 1939 } 1940 1941 s = &sessions[sessions_first_unused]; 1942 if (s->used) { 1943 fatal("%s: session %d already used", 1944 __func__, sessions_first_unused); 1945 } 1946 sessions_first_unused = s->next_unused; 1947 s->used = 1; 1948 s->next_unused = -1; 1949 debug("session_new: session %d", s->self); 1950 1951 return s; 1952 } 1953 1954 static void 1955 session_dump(void) 1956 { 1957 int i; 1958 for (i = 0; i < sessions_nalloc; i++) { 1959 Session *s = &sessions[i]; 1960 1961 debug("dump: used %d next_unused %d session %d %p " 1962 "channel %d pid %ld", 1963 s->used, 1964 s->next_unused, 1965 s->self, 1966 s, 1967 s->chanid, 1968 (long)s->pid); 1969 } 1970 } 1971 1972 int 1973 session_open(Authctxt *authctxt, int chanid) 1974 { 1975 Session *s = session_new(); 1976 debug("session_open: channel %d", chanid); 1977 if (s == NULL) { 1978 error("no more sessions"); 1979 return 0; 1980 } 1981 s->authctxt = authctxt; 1982 s->pw = authctxt->pw; 1983 if (s->pw == NULL || !authctxt->valid) 1984 fatal("no user for session %d", s->self); 1985 debug("session_open: session %d: link with channel %d", s->self, chanid); 1986 s->chanid = chanid; 1987 return 1; 1988 } 1989 1990 Session * 1991 session_by_tty(char *tty) 1992 { 1993 int i; 1994 for (i = 0; i < sessions_nalloc; i++) { 1995 Session *s = &sessions[i]; 1996 if (s->used && s->ttyfd != -1 && strcmp(s->tty, tty) == 0) { 1997 debug("session_by_tty: session %d tty %s", i, tty); 1998 return s; 1999 } 2000 } 2001 debug("session_by_tty: unknown tty %.100s", tty); 2002 session_dump(); 2003 return NULL; 2004 } 2005 2006 static Session * 2007 session_by_channel(int id) 2008 { 2009 int i; 2010 for (i = 0; i < sessions_nalloc; i++) { 2011 Session *s = &sessions[i]; 2012 if (s->used && s->chanid == id) { 2013 debug("session_by_channel: session %d channel %d", 2014 i, id); 2015 return s; 2016 } 2017 } 2018 debug("session_by_channel: unknown channel %d", id); 2019 session_dump(); 2020 return NULL; 2021 } 2022 2023 static Session * 2024 session_by_x11_channel(int id) 2025 { 2026 int i, j; 2027 2028 for (i = 0; i < sessions_nalloc; i++) { 2029 Session *s = &sessions[i]; 2030 2031 if (s->x11_chanids == NULL || !s->used) 2032 continue; 2033 for (j = 0; s->x11_chanids[j] != -1; j++) { 2034 if (s->x11_chanids[j] == id) { 2035 debug("session_by_x11_channel: session %d " 2036 "channel %d", s->self, id); 2037 return s; 2038 } 2039 } 2040 } 2041 debug("session_by_x11_channel: unknown channel %d", id); 2042 session_dump(); 2043 return NULL; 2044 } 2045 2046 static Session * 2047 session_by_pid(pid_t pid) 2048 { 2049 int i; 2050 debug("session_by_pid: pid %ld", (long)pid); 2051 for (i = 0; i < sessions_nalloc; i++) { 2052 Session *s = &sessions[i]; 2053 if (s->used && s->pid == pid) 2054 return s; 2055 } 2056 error("session_by_pid: unknown pid %ld", (long)pid); 2057 session_dump(); 2058 return NULL; 2059 } 2060 2061 static int 2062 session_window_change_req(Session *s) 2063 { 2064 s->col = packet_get_int(); 2065 s->row = packet_get_int(); 2066 s->xpixel = packet_get_int(); 2067 s->ypixel = packet_get_int(); 2068 packet_check_eom(); 2069 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 2070 return 1; 2071 } 2072 2073 static int 2074 session_pty_req(Session *s) 2075 { 2076 u_int len; 2077 int n_bytes; 2078 2079 if (no_pty_flag || !options.permit_tty) { 2080 debug("Allocating a pty not permitted for this authentication."); 2081 return 0; 2082 } 2083 if (s->ttyfd != -1) { 2084 packet_disconnect("Protocol error: you already have a pty."); 2085 return 0; 2086 } 2087 2088 s->term = packet_get_string(&len); 2089 2090 if (compat20) { 2091 s->col = packet_get_int(); 2092 s->row = packet_get_int(); 2093 } else { 2094 s->row = packet_get_int(); 2095 s->col = packet_get_int(); 2096 } 2097 s->xpixel = packet_get_int(); 2098 s->ypixel = packet_get_int(); 2099 2100 if (strcmp(s->term, "") == 0) { 2101 free(s->term); 2102 s->term = NULL; 2103 } 2104 2105 /* Allocate a pty and open it. */ 2106 debug("Allocating pty."); 2107 if (!PRIVSEP(pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, 2108 sizeof(s->tty)))) { 2109 free(s->term); 2110 s->term = NULL; 2111 s->ptyfd = -1; 2112 s->ttyfd = -1; 2113 error("session_pty_req: session %d alloc failed", s->self); 2114 return 0; 2115 } 2116 debug("session_pty_req: session %d alloc %s", s->self, s->tty); 2117 2118 /* for SSH1 the tty modes length is not given */ 2119 if (!compat20) 2120 n_bytes = packet_remaining(); 2121 tty_parse_modes(s->ttyfd, &n_bytes); 2122 2123 if (!use_privsep) 2124 pty_setowner(s->pw, s->tty); 2125 2126 /* Set window size from the packet. */ 2127 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 2128 2129 packet_check_eom(); 2130 session_proctitle(s); 2131 return 1; 2132 } 2133 2134 static int 2135 session_subsystem_req(Session *s) 2136 { 2137 struct stat st; 2138 u_int len; 2139 int success = 0; 2140 char *prog, *cmd; 2141 u_int i; 2142 2143 s->subsys = packet_get_string(&len); 2144 packet_check_eom(); 2145 debug2("subsystem request for %.100s by user %s", s->subsys, 2146 s->pw->pw_name); 2147 2148 for (i = 0; i < options.num_subsystems; i++) { 2149 if (strcmp(s->subsys, options.subsystem_name[i]) == 0) { 2150 prog = options.subsystem_command[i]; 2151 cmd = options.subsystem_args[i]; 2152 if (strcmp(INTERNAL_SFTP_NAME, prog) == 0) { 2153 s->is_subsystem = SUBSYSTEM_INT_SFTP; 2154 debug("subsystem: %s", prog); 2155 } else { 2156 if (stat(prog, &st) < 0) 2157 debug("subsystem: cannot stat %s: %s", 2158 prog, strerror(errno)); 2159 s->is_subsystem = SUBSYSTEM_EXT; 2160 debug("subsystem: exec() %s", cmd); 2161 } 2162 success = do_exec(s, cmd) == 0; 2163 break; 2164 } 2165 } 2166 2167 if (!success) 2168 logit("subsystem request for %.100s by user %s failed, " 2169 "subsystem not found", s->subsys, s->pw->pw_name); 2170 2171 return success; 2172 } 2173 2174 static int 2175 session_x11_req(Session *s) 2176 { 2177 int success; 2178 2179 if (s->auth_proto != NULL || s->auth_data != NULL) { 2180 error("session_x11_req: session %d: " 2181 "x11 forwarding already active", s->self); 2182 return 0; 2183 } 2184 s->single_connection = packet_get_char(); 2185 s->auth_proto = packet_get_string(NULL); 2186 s->auth_data = packet_get_string(NULL); 2187 s->screen = packet_get_int(); 2188 packet_check_eom(); 2189 2190 success = session_setup_x11fwd(s); 2191 if (!success) { 2192 free(s->auth_proto); 2193 free(s->auth_data); 2194 s->auth_proto = NULL; 2195 s->auth_data = NULL; 2196 } 2197 return success; 2198 } 2199 2200 static int 2201 session_shell_req(Session *s) 2202 { 2203 packet_check_eom(); 2204 return do_exec(s, NULL) == 0; 2205 } 2206 2207 static int 2208 session_exec_req(Session *s) 2209 { 2210 u_int len, success; 2211 2212 char *command = packet_get_string(&len); 2213 packet_check_eom(); 2214 success = do_exec(s, command) == 0; 2215 free(command); 2216 return success; 2217 } 2218 2219 static int 2220 session_break_req(Session *s) 2221 { 2222 2223 packet_get_int(); /* ignored */ 2224 packet_check_eom(); 2225 2226 if (s->ptymaster == -1 || tcsendbreak(s->ptymaster, 0) < 0) 2227 return 0; 2228 return 1; 2229 } 2230 2231 static int 2232 session_env_req(Session *s) 2233 { 2234 char *name, *val; 2235 u_int name_len, val_len, i; 2236 2237 name = packet_get_cstring(&name_len); 2238 val = packet_get_cstring(&val_len); 2239 packet_check_eom(); 2240 2241 /* Don't set too many environment variables */ 2242 if (s->num_env > 128) { 2243 debug2("Ignoring env request %s: too many env vars", name); 2244 goto fail; 2245 } 2246 2247 for (i = 0; i < options.num_accept_env; i++) { 2248 if (match_pattern(name, options.accept_env[i])) { 2249 debug2("Setting env %d: %s=%s", s->num_env, name, val); 2250 s->env = xrealloc(s->env, s->num_env + 1, 2251 sizeof(*s->env)); 2252 s->env[s->num_env].name = name; 2253 s->env[s->num_env].val = val; 2254 s->num_env++; 2255 return (1); 2256 } 2257 } 2258 debug2("Ignoring env request %s: disallowed name", name); 2259 2260 fail: 2261 free(name); 2262 free(val); 2263 return (0); 2264 } 2265 2266 static int 2267 session_auth_agent_req(Session *s) 2268 { 2269 static int called = 0; 2270 packet_check_eom(); 2271 if (no_agent_forwarding_flag || !options.allow_agent_forwarding) { 2272 debug("session_auth_agent_req: no_agent_forwarding_flag"); 2273 return 0; 2274 } 2275 if (called) { 2276 return 0; 2277 } else { 2278 called = 1; 2279 return auth_input_request_forwarding(s->pw); 2280 } 2281 } 2282 2283 int 2284 session_input_channel_req(Channel *c, const char *rtype) 2285 { 2286 int success = 0; 2287 Session *s; 2288 2289 if ((s = session_by_channel(c->self)) == NULL) { 2290 logit("session_input_channel_req: no session %d req %.100s", 2291 c->self, rtype); 2292 return 0; 2293 } 2294 debug("session_input_channel_req: session %d req %s", s->self, rtype); 2295 2296 /* 2297 * a session is in LARVAL state until a shell, a command 2298 * or a subsystem is executed 2299 */ 2300 if (c->type == SSH_CHANNEL_LARVAL) { 2301 if (strcmp(rtype, "shell") == 0) { 2302 success = session_shell_req(s); 2303 } else if (strcmp(rtype, "exec") == 0) { 2304 success = session_exec_req(s); 2305 } else if (strcmp(rtype, "pty-req") == 0) { 2306 success = session_pty_req(s); 2307 } else if (strcmp(rtype, "x11-req") == 0) { 2308 success = session_x11_req(s); 2309 } else if (strcmp(rtype, "auth-agent-req (at) openssh.com") == 0) { 2310 success = session_auth_agent_req(s); 2311 } else if (strcmp(rtype, "subsystem") == 0) { 2312 success = session_subsystem_req(s); 2313 } else if (strcmp(rtype, "env") == 0) { 2314 success = session_env_req(s); 2315 } 2316 } 2317 if (strcmp(rtype, "window-change") == 0) { 2318 success = session_window_change_req(s); 2319 } else if (strcmp(rtype, "break") == 0) { 2320 success = session_break_req(s); 2321 } 2322 2323 return success; 2324 } 2325 2326 void 2327 session_set_fds(Session *s, int fdin, int fdout, int fderr, int ignore_fderr, 2328 int is_tty) 2329 { 2330 if (!compat20) 2331 fatal("session_set_fds: called for proto != 2.0"); 2332 /* 2333 * now that have a child and a pipe to the child, 2334 * we can activate our channel and register the fd's 2335 */ 2336 if (s->chanid == -1) 2337 fatal("no channel for session %d", s->self); 2338 channel_set_fds(s->chanid, 2339 fdout, fdin, fderr, 2340 ignore_fderr ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ, 2341 1, is_tty, CHAN_SES_WINDOW_DEFAULT); 2342 } 2343 2344 /* 2345 * Function to perform pty cleanup. Also called if we get aborted abnormally 2346 * (e.g., due to a dropped connection). 2347 */ 2348 void 2349 session_pty_cleanup2(Session *s) 2350 { 2351 if (s == NULL) { 2352 error("session_pty_cleanup: no session"); 2353 return; 2354 } 2355 if (s->ttyfd == -1) 2356 return; 2357 2358 debug("session_pty_cleanup: session %d release %s", s->self, s->tty); 2359 2360 /* Record that the user has logged out. */ 2361 if (s->pid != 0) 2362 record_logout(s->pid, s->tty, s->pw->pw_name); 2363 2364 /* Release the pseudo-tty. */ 2365 if (getuid() == 0) 2366 pty_release(s->tty); 2367 2368 /* 2369 * Close the server side of the socket pairs. We must do this after 2370 * the pty cleanup, so that another process doesn't get this pty 2371 * while we're still cleaning up. 2372 */ 2373 if (s->ptymaster != -1 && close(s->ptymaster) < 0) 2374 error("close(s->ptymaster/%d): %s", 2375 s->ptymaster, strerror(errno)); 2376 2377 /* unlink pty from session */ 2378 s->ttyfd = -1; 2379 } 2380 2381 void 2382 session_pty_cleanup(Session *s) 2383 { 2384 PRIVSEP(session_pty_cleanup2(s)); 2385 } 2386 2387 static char * 2388 sig2name(int sig) 2389 { 2390 #define SSH_SIG(x) if (sig == SIG ## x) return #x 2391 SSH_SIG(ABRT); 2392 SSH_SIG(ALRM); 2393 SSH_SIG(FPE); 2394 SSH_SIG(HUP); 2395 SSH_SIG(ILL); 2396 SSH_SIG(INT); 2397 SSH_SIG(KILL); 2398 SSH_SIG(PIPE); 2399 SSH_SIG(QUIT); 2400 SSH_SIG(SEGV); 2401 SSH_SIG(TERM); 2402 SSH_SIG(USR1); 2403 SSH_SIG(USR2); 2404 #undef SSH_SIG 2405 return "SIG (at) openssh.com"; 2406 } 2407 2408 static void 2409 session_close_x11(int id) 2410 { 2411 Channel *c; 2412 2413 if ((c = channel_by_id(id)) == NULL) { 2414 debug("session_close_x11: x11 channel %d missing", id); 2415 } else { 2416 /* Detach X11 listener */ 2417 debug("session_close_x11: detach x11 channel %d", id); 2418 channel_cancel_cleanup(id); 2419 if (c->ostate != CHAN_OUTPUT_CLOSED) 2420 chan_mark_dead(c); 2421 } 2422 } 2423 2424 static void 2425 session_close_single_x11(int id, void *arg) 2426 { 2427 Session *s; 2428 u_int i; 2429 2430 debug3("session_close_single_x11: channel %d", id); 2431 channel_cancel_cleanup(id); 2432 if ((s = session_by_x11_channel(id)) == NULL) 2433 fatal("session_close_single_x11: no x11 channel %d", id); 2434 for (i = 0; s->x11_chanids[i] != -1; i++) { 2435 debug("session_close_single_x11: session %d: " 2436 "closing channel %d", s->self, s->x11_chanids[i]); 2437 /* 2438 * The channel "id" is already closing, but make sure we 2439 * close all of its siblings. 2440 */ 2441 if (s->x11_chanids[i] != id) 2442 session_close_x11(s->x11_chanids[i]); 2443 } 2444 free(s->x11_chanids); 2445 s->x11_chanids = NULL; 2446 free(s->display); 2447 s->display = NULL; 2448 free(s->auth_proto); 2449 s->auth_proto = NULL; 2450 free(s->auth_data); 2451 s->auth_data = NULL; 2452 free(s->auth_display); 2453 s->auth_display = NULL; 2454 } 2455 2456 static void 2457 session_exit_message(Session *s, int status) 2458 { 2459 Channel *c; 2460 2461 if ((c = channel_lookup(s->chanid)) == NULL) 2462 fatal("session_exit_message: session %d: no channel %d", 2463 s->self, s->chanid); 2464 debug("session_exit_message: session %d channel %d pid %ld", 2465 s->self, s->chanid, (long)s->pid); 2466 2467 if (WIFEXITED(status)) { 2468 channel_request_start(s->chanid, "exit-status", 0); 2469 packet_put_int(WEXITSTATUS(status)); 2470 packet_send(); 2471 } else if (WIFSIGNALED(status)) { 2472 channel_request_start(s->chanid, "exit-signal", 0); 2473 packet_put_cstring(sig2name(WTERMSIG(status))); 2474 #ifdef WCOREDUMP 2475 packet_put_char(WCOREDUMP(status)? 1 : 0); 2476 #else /* WCOREDUMP */ 2477 packet_put_char(0); 2478 #endif /* WCOREDUMP */ 2479 packet_put_cstring(""); 2480 packet_put_cstring(""); 2481 packet_send(); 2482 } else { 2483 /* Some weird exit cause. Just exit. */ 2484 packet_disconnect("wait returned status %04x.", status); 2485 } 2486 2487 /* disconnect channel */ 2488 debug("session_exit_message: release channel %d", s->chanid); 2489 2490 /* 2491 * Adjust cleanup callback attachment to send close messages when 2492 * the channel gets EOF. The session will be then be closed 2493 * by session_close_by_channel when the childs close their fds. 2494 */ 2495 channel_register_cleanup(c->self, session_close_by_channel, 1); 2496 2497 /* 2498 * emulate a write failure with 'chan_write_failed', nobody will be 2499 * interested in data we write. 2500 * Note that we must not call 'chan_read_failed', since there could 2501 * be some more data waiting in the pipe. 2502 */ 2503 if (c->ostate != CHAN_OUTPUT_CLOSED) 2504 chan_write_failed(c); 2505 } 2506 2507 void 2508 session_close(Session *s) 2509 { 2510 u_int i; 2511 2512 debug("session_close: session %d pid %ld", s->self, (long)s->pid); 2513 if (s->ttyfd != -1) 2514 session_pty_cleanup(s); 2515 free(s->term); 2516 free(s->display); 2517 free(s->x11_chanids); 2518 free(s->auth_display); 2519 free(s->auth_data); 2520 free(s->auth_proto); 2521 free(s->subsys); 2522 if (s->env != NULL) { 2523 for (i = 0; i < s->num_env; i++) { 2524 free(s->env[i].name); 2525 free(s->env[i].val); 2526 } 2527 free(s->env); 2528 } 2529 session_proctitle(s); 2530 session_unused(s->self); 2531 } 2532 2533 void 2534 session_close_by_pid(pid_t pid, int status) 2535 { 2536 Session *s = session_by_pid(pid); 2537 if (s == NULL) { 2538 debug("session_close_by_pid: no session for pid %ld", 2539 (long)pid); 2540 return; 2541 } 2542 if (s->chanid != -1) 2543 session_exit_message(s, status); 2544 if (s->ttyfd != -1) 2545 session_pty_cleanup(s); 2546 s->pid = 0; 2547 } 2548 2549 /* 2550 * this is called when a channel dies before 2551 * the session 'child' itself dies 2552 */ 2553 void 2554 session_close_by_channel(int id, void *arg) 2555 { 2556 Session *s = session_by_channel(id); 2557 u_int i; 2558 2559 if (s == NULL) { 2560 debug("session_close_by_channel: no session for id %d", id); 2561 return; 2562 } 2563 debug("session_close_by_channel: channel %d child %ld", 2564 id, (long)s->pid); 2565 if (s->pid != 0) { 2566 debug("session_close_by_channel: channel %d: has child", id); 2567 /* 2568 * delay detach of session, but release pty, since 2569 * the fd's to the child are already closed 2570 */ 2571 if (s->ttyfd != -1) 2572 session_pty_cleanup(s); 2573 return; 2574 } 2575 /* detach by removing callback */ 2576 channel_cancel_cleanup(s->chanid); 2577 2578 /* Close any X11 listeners associated with this session */ 2579 if (s->x11_chanids != NULL) { 2580 for (i = 0; s->x11_chanids[i] != -1; i++) { 2581 session_close_x11(s->x11_chanids[i]); 2582 s->x11_chanids[i] = -1; 2583 } 2584 } 2585 2586 s->chanid = -1; 2587 session_close(s); 2588 } 2589 2590 void 2591 session_destroy_all(void (*closefunc)(Session *)) 2592 { 2593 int i; 2594 for (i = 0; i < sessions_nalloc; i++) { 2595 Session *s = &sessions[i]; 2596 if (s->used) { 2597 if (closefunc != NULL) 2598 closefunc(s); 2599 else 2600 session_close(s); 2601 } 2602 } 2603 } 2604 2605 static char * 2606 session_tty_list(void) 2607 { 2608 static char buf[1024]; 2609 int i; 2610 char *cp; 2611 2612 buf[0] = '\0'; 2613 for (i = 0; i < sessions_nalloc; i++) { 2614 Session *s = &sessions[i]; 2615 if (s->used && s->ttyfd != -1) { 2616 2617 if (strncmp(s->tty, "/dev/", 5) != 0) { 2618 cp = strrchr(s->tty, '/'); 2619 cp = (cp == NULL) ? s->tty : cp + 1; 2620 } else 2621 cp = s->tty + 5; 2622 2623 if (buf[0] != '\0') 2624 strlcat(buf, ",", sizeof buf); 2625 strlcat(buf, cp, sizeof buf); 2626 } 2627 } 2628 if (buf[0] == '\0') 2629 strlcpy(buf, "notty", sizeof buf); 2630 return buf; 2631 } 2632 2633 void 2634 session_proctitle(Session *s) 2635 { 2636 if (s->pw == NULL) 2637 error("no user for session %d", s->self); 2638 else 2639 setproctitle("%s@%s", s->pw->pw_name, session_tty_list()); 2640 } 2641 2642 int 2643 session_setup_x11fwd(Session *s) 2644 { 2645 struct stat st; 2646 char display[512], auth_display[512]; 2647 char hostname[NI_MAXHOST]; 2648 u_int i; 2649 2650 if (no_x11_forwarding_flag) { 2651 packet_send_debug("X11 forwarding disabled in user configuration file."); 2652 return 0; 2653 } 2654 if (!options.x11_forwarding) { 2655 debug("X11 forwarding disabled in server configuration file."); 2656 return 0; 2657 } 2658 if (options.xauth_location == NULL || 2659 (stat(options.xauth_location, &st) == -1)) { 2660 packet_send_debug("No xauth program; cannot forward with spoofing."); 2661 return 0; 2662 } 2663 if (options.use_login) { 2664 packet_send_debug("X11 forwarding disabled; " 2665 "not compatible with UseLogin=yes."); 2666 return 0; 2667 } 2668 if (s->display != NULL) { 2669 debug("X11 display already set."); 2670 return 0; 2671 } 2672 if (x11_create_display_inet(options.x11_display_offset, 2673 options.x11_use_localhost, s->single_connection, 2674 &s->display_number, &s->x11_chanids) == -1) { 2675 debug("x11_create_display_inet failed."); 2676 return 0; 2677 } 2678 for (i = 0; s->x11_chanids[i] != -1; i++) { 2679 channel_register_cleanup(s->x11_chanids[i], 2680 session_close_single_x11, 0); 2681 } 2682 2683 /* Set up a suitable value for the DISPLAY variable. */ 2684 if (gethostname(hostname, sizeof(hostname)) < 0) 2685 fatal("gethostname: %.100s", strerror(errno)); 2686 /* 2687 * auth_display must be used as the displayname when the 2688 * authorization entry is added with xauth(1). This will be 2689 * different than the DISPLAY string for localhost displays. 2690 */ 2691 if (options.x11_use_localhost) { 2692 snprintf(display, sizeof display, "localhost:%u.%u", 2693 s->display_number, s->screen); 2694 snprintf(auth_display, sizeof auth_display, "unix:%u.%u", 2695 s->display_number, s->screen); 2696 s->display = xstrdup(display); 2697 s->auth_display = xstrdup(auth_display); 2698 } else { 2699 #ifdef IPADDR_IN_DISPLAY 2700 struct hostent *he; 2701 struct in_addr my_addr; 2702 2703 he = gethostbyname(hostname); 2704 if (he == NULL) { 2705 error("Can't get IP address for X11 DISPLAY."); 2706 packet_send_debug("Can't get IP address for X11 DISPLAY."); 2707 return 0; 2708 } 2709 memcpy(&my_addr, he->h_addr_list[0], sizeof(struct in_addr)); 2710 snprintf(display, sizeof display, "%.50s:%u.%u", inet_ntoa(my_addr), 2711 s->display_number, s->screen); 2712 #else 2713 snprintf(display, sizeof display, "%.400s:%u.%u", hostname, 2714 s->display_number, s->screen); 2715 #endif 2716 s->display = xstrdup(display); 2717 s->auth_display = xstrdup(display); 2718 } 2719 2720 return 1; 2721 } 2722 2723 static void 2724 do_authenticated2(Authctxt *authctxt) 2725 { 2726 server_loop2(authctxt); 2727 } 2728 2729 void 2730 do_cleanup(Authctxt *authctxt) 2731 { 2732 static int called = 0; 2733 2734 debug("do_cleanup"); 2735 2736 /* no cleanup if we're in the child for login shell */ 2737 if (is_child) 2738 return; 2739 2740 /* avoid double cleanup */ 2741 if (called) 2742 return; 2743 called = 1; 2744 2745 if (authctxt == NULL) 2746 return; 2747 2748 #ifdef USE_PAM 2749 if (options.use_pam) { 2750 sshpam_cleanup(); 2751 sshpam_thread_cleanup(); 2752 } 2753 #endif 2754 2755 if (!authctxt->authenticated) 2756 return; 2757 2758 #ifdef KRB5 2759 if (options.kerberos_ticket_cleanup && 2760 authctxt->krb5_ctx) 2761 krb5_cleanup_proc(authctxt); 2762 #endif 2763 2764 #ifdef GSSAPI 2765 if (compat20 && options.gss_cleanup_creds) 2766 ssh_gssapi_cleanup_creds(); 2767 #endif 2768 2769 /* remove agent socket */ 2770 auth_sock_cleanup_proc(authctxt->pw); 2771 2772 /* 2773 * Cleanup ptys/utmp only if privsep is disabled, 2774 * or if running in monitor. 2775 */ 2776 if (!use_privsep || mm_is_monitor()) 2777 session_destroy_all(session_pty_cleanup2); 2778 } 2779