1 /* $OpenBSD: session.c,v 1.246 2009/04/17 19:23:06 stevesk Exp $ */ 2 /* 3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 4 * All rights reserved 5 * 6 * As far as I am concerned, the code I have written for this software 7 * can be used freely for any purpose. Any derived versions of this 8 * software must be clearly marked as such, and if the derived work is 9 * incompatible with the protocol description in the RFC file, it must be 10 * called by a name other than "ssh" or "Secure Shell". 11 * 12 * SSH2 support by Markus Friedl. 13 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 14 * 15 * Redistribution and use in source and binary forms, with or without 16 * modification, are permitted provided that the following conditions 17 * are met: 18 * 1. Redistributions of source code must retain the above copyright 19 * notice, this list of conditions and the following disclaimer. 20 * 2. Redistributions in binary form must reproduce the above copyright 21 * notice, this list of conditions and the following disclaimer in the 22 * documentation and/or other materials provided with the distribution. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 25 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 26 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 27 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 28 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 29 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 30 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 31 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 32 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 33 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 34 */ 35 36 #include "includes.h" 37 38 #include <sys/types.h> 39 #include <sys/param.h> 40 #ifdef HAVE_SYS_STAT_H 41 # include <sys/stat.h> 42 #endif 43 #include <sys/socket.h> 44 #include <sys/un.h> 45 #include <sys/wait.h> 46 47 #include <arpa/inet.h> 48 49 #include <errno.h> 50 #include <grp.h> 51 #ifdef HAVE_PATHS_H 52 #include <paths.h> 53 #endif 54 #include <pwd.h> 55 #include <signal.h> 56 #include <stdarg.h> 57 #include <stdio.h> 58 #include <stdlib.h> 59 #include <string.h> 60 #include <unistd.h> 61 62 #include "openbsd-compat/sys-queue.h" 63 #include "xmalloc.h" 64 #include "ssh.h" 65 #include "ssh1.h" 66 #include "ssh2.h" 67 #include "sshpty.h" 68 #include "packet.h" 69 #include "buffer.h" 70 #include "match.h" 71 #include "uidswap.h" 72 #include "compat.h" 73 #include "channels.h" 74 #include "key.h" 75 #include "cipher.h" 76 #ifdef GSSAPI 77 #include "ssh-gss.h" 78 #endif 79 #include "hostfile.h" 80 #include "auth.h" 81 #include "auth-options.h" 82 #include "pathnames.h" 83 #include "log.h" 84 #include "servconf.h" 85 #include "sshlogin.h" 86 #include "serverloop.h" 87 #include "canohost.h" 88 #include "misc.h" 89 #include "session.h" 90 #include "kex.h" 91 #include "monitor_wrap.h" 92 #include "sftp.h" 93 94 #if defined(KRB5) && defined(USE_AFS) 95 #include <kafs.h> 96 #endif 97 98 #define IS_INTERNAL_SFTP(c) \ 99 (!strncmp(c, INTERNAL_SFTP_NAME, sizeof(INTERNAL_SFTP_NAME) - 1) && \ 100 (c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\0' || \ 101 c[sizeof(INTERNAL_SFTP_NAME) - 1] == ' ' || \ 102 c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\t')) 103 104 /* func */ 105 106 Session *session_new(void); 107 void session_set_fds(Session *, int, int, int, int); 108 void session_pty_cleanup(Session *); 109 void session_proctitle(Session *); 110 int session_setup_x11fwd(Session *); 111 int do_exec_pty(Session *, const char *); 112 int do_exec_no_pty(Session *, const char *); 113 int do_exec(Session *, const char *); 114 void do_login(Session *, const char *); 115 #ifdef LOGIN_NEEDS_UTMPX 116 static void do_pre_login(Session *s); 117 #endif 118 void do_child(Session *, const char *); 119 void do_motd(void); 120 int check_quietlogin(Session *, const char *); 121 122 static void do_authenticated1(Authctxt *); 123 static void do_authenticated2(Authctxt *); 124 125 static int session_pty_req(Session *); 126 127 /* import */ 128 extern ServerOptions options; 129 extern char *__progname; 130 extern int log_stderr; 131 extern int debug_flag; 132 extern u_int utmp_len; 133 extern int startup_pipe; 134 extern void destroy_sensitive_data(void); 135 extern Buffer loginmsg; 136 137 /* original command from peer. */ 138 const char *original_command = NULL; 139 140 /* data */ 141 static int sessions_first_unused = -1; 142 static int sessions_nalloc = 0; 143 static Session *sessions = NULL; 144 145 #define SUBSYSTEM_NONE 0 146 #define SUBSYSTEM_EXT 1 147 #define SUBSYSTEM_INT_SFTP 2 148 149 #ifdef HAVE_LOGIN_CAP 150 login_cap_t *lc; 151 #endif 152 153 static int is_child = 0; 154 155 /* Name and directory of socket for authentication agent forwarding. */ 156 static char *auth_sock_name = NULL; 157 static char *auth_sock_dir = NULL; 158 159 /* removes the agent forwarding socket */ 160 161 static void 162 auth_sock_cleanup_proc(struct passwd *pw) 163 { 164 if (auth_sock_name != NULL) { 165 temporarily_use_uid(pw); 166 unlink(auth_sock_name); 167 rmdir(auth_sock_dir); 168 auth_sock_name = NULL; 169 restore_uid(); 170 } 171 } 172 173 static int 174 auth_input_request_forwarding(struct passwd * pw) 175 { 176 Channel *nc; 177 int sock = -1; 178 struct sockaddr_un sunaddr; 179 180 if (auth_sock_name != NULL) { 181 error("authentication forwarding requested twice."); 182 return 0; 183 } 184 185 /* Temporarily drop privileged uid for mkdir/bind. */ 186 temporarily_use_uid(pw); 187 188 /* Allocate a buffer for the socket name, and format the name. */ 189 auth_sock_dir = xstrdup("/tmp/ssh-XXXXXXXXXX"); 190 191 /* Create private directory for socket */ 192 if (mkdtemp(auth_sock_dir) == NULL) { 193 packet_send_debug("Agent forwarding disabled: " 194 "mkdtemp() failed: %.100s", strerror(errno)); 195 restore_uid(); 196 xfree(auth_sock_dir); 197 auth_sock_dir = NULL; 198 goto authsock_err; 199 } 200 201 xasprintf(&auth_sock_name, "%s/agent.%ld", 202 auth_sock_dir, (long) getpid()); 203 204 /* Create the socket. */ 205 sock = socket(AF_UNIX, SOCK_STREAM, 0); 206 if (sock < 0) { 207 error("socket: %.100s", strerror(errno)); 208 restore_uid(); 209 goto authsock_err; 210 } 211 212 /* Bind it to the name. */ 213 memset(&sunaddr, 0, sizeof(sunaddr)); 214 sunaddr.sun_family = AF_UNIX; 215 strlcpy(sunaddr.sun_path, auth_sock_name, sizeof(sunaddr.sun_path)); 216 217 if (bind(sock, (struct sockaddr *)&sunaddr, sizeof(sunaddr)) < 0) { 218 error("bind: %.100s", strerror(errno)); 219 restore_uid(); 220 goto authsock_err; 221 } 222 223 /* Restore the privileged uid. */ 224 restore_uid(); 225 226 /* Start listening on the socket. */ 227 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) { 228 error("listen: %.100s", strerror(errno)); 229 goto authsock_err; 230 } 231 232 /* Allocate a channel for the authentication agent socket. */ 233 nc = channel_new("auth socket", 234 SSH_CHANNEL_AUTH_SOCKET, sock, sock, -1, 235 CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 236 0, "auth socket", 1); 237 nc->path = xstrdup(auth_sock_name); 238 return 1; 239 240 authsock_err: 241 if (auth_sock_name != NULL) 242 xfree(auth_sock_name); 243 if (auth_sock_dir != NULL) { 244 rmdir(auth_sock_dir); 245 xfree(auth_sock_dir); 246 } 247 if (sock != -1) 248 close(sock); 249 auth_sock_name = NULL; 250 auth_sock_dir = NULL; 251 return 0; 252 } 253 254 static void 255 display_loginmsg(void) 256 { 257 if (buffer_len(&loginmsg) > 0) { 258 buffer_append(&loginmsg, "\0", 1); 259 printf("%s", (char *)buffer_ptr(&loginmsg)); 260 buffer_clear(&loginmsg); 261 } 262 } 263 264 void 265 do_authenticated(Authctxt *authctxt) 266 { 267 setproctitle("%s", authctxt->pw->pw_name); 268 269 /* setup the channel layer */ 270 if (!no_port_forwarding_flag && options.allow_tcp_forwarding) 271 channel_permit_all_opens(); 272 273 if (compat20) 274 do_authenticated2(authctxt); 275 else 276 do_authenticated1(authctxt); 277 278 do_cleanup(authctxt); 279 } 280 281 /* 282 * Prepares for an interactive session. This is called after the user has 283 * been successfully authenticated. During this message exchange, pseudo 284 * terminals are allocated, X11, TCP/IP, and authentication agent forwardings 285 * are requested, etc. 286 */ 287 static void 288 do_authenticated1(Authctxt *authctxt) 289 { 290 Session *s; 291 char *command; 292 int success, type, screen_flag; 293 int enable_compression_after_reply = 0; 294 u_int proto_len, data_len, dlen, compression_level = 0; 295 296 s = session_new(); 297 if (s == NULL) { 298 error("no more sessions"); 299 return; 300 } 301 s->authctxt = authctxt; 302 s->pw = authctxt->pw; 303 304 /* 305 * We stay in this loop until the client requests to execute a shell 306 * or a command. 307 */ 308 for (;;) { 309 success = 0; 310 311 /* Get a packet from the client. */ 312 type = packet_read(); 313 314 /* Process the packet. */ 315 switch (type) { 316 case SSH_CMSG_REQUEST_COMPRESSION: 317 compression_level = packet_get_int(); 318 packet_check_eom(); 319 if (compression_level < 1 || compression_level > 9) { 320 packet_send_debug("Received invalid compression level %d.", 321 compression_level); 322 break; 323 } 324 if (options.compression == COMP_NONE) { 325 debug2("compression disabled"); 326 break; 327 } 328 /* Enable compression after we have responded with SUCCESS. */ 329 enable_compression_after_reply = 1; 330 success = 1; 331 break; 332 333 case SSH_CMSG_REQUEST_PTY: 334 success = session_pty_req(s); 335 break; 336 337 case SSH_CMSG_X11_REQUEST_FORWARDING: 338 s->auth_proto = packet_get_string(&proto_len); 339 s->auth_data = packet_get_string(&data_len); 340 341 screen_flag = packet_get_protocol_flags() & 342 SSH_PROTOFLAG_SCREEN_NUMBER; 343 debug2("SSH_PROTOFLAG_SCREEN_NUMBER: %d", screen_flag); 344 345 if (packet_remaining() == 4) { 346 if (!screen_flag) 347 debug2("Buggy client: " 348 "X11 screen flag missing"); 349 s->screen = packet_get_int(); 350 } else { 351 s->screen = 0; 352 } 353 packet_check_eom(); 354 success = session_setup_x11fwd(s); 355 if (!success) { 356 xfree(s->auth_proto); 357 xfree(s->auth_data); 358 s->auth_proto = NULL; 359 s->auth_data = NULL; 360 } 361 break; 362 363 case SSH_CMSG_AGENT_REQUEST_FORWARDING: 364 if (!options.allow_agent_forwarding || 365 no_agent_forwarding_flag || compat13) { 366 debug("Authentication agent forwarding not permitted for this authentication."); 367 break; 368 } 369 debug("Received authentication agent forwarding request."); 370 success = auth_input_request_forwarding(s->pw); 371 break; 372 373 case SSH_CMSG_PORT_FORWARD_REQUEST: 374 if (no_port_forwarding_flag) { 375 debug("Port forwarding not permitted for this authentication."); 376 break; 377 } 378 if (!options.allow_tcp_forwarding) { 379 debug("Port forwarding not permitted."); 380 break; 381 } 382 debug("Received TCP/IP port forwarding request."); 383 if (channel_input_port_forward_request(s->pw->pw_uid == 0, 384 options.gateway_ports) < 0) { 385 debug("Port forwarding failed."); 386 break; 387 } 388 success = 1; 389 break; 390 391 case SSH_CMSG_MAX_PACKET_SIZE: 392 if (packet_set_maxsize(packet_get_int()) > 0) 393 success = 1; 394 break; 395 396 case SSH_CMSG_EXEC_SHELL: 397 case SSH_CMSG_EXEC_CMD: 398 if (type == SSH_CMSG_EXEC_CMD) { 399 command = packet_get_string(&dlen); 400 debug("Exec command '%.500s'", command); 401 if (do_exec(s, command) != 0) 402 packet_disconnect( 403 "command execution failed"); 404 xfree(command); 405 } else { 406 if (do_exec(s, NULL) != 0) 407 packet_disconnect( 408 "shell execution failed"); 409 } 410 packet_check_eom(); 411 session_close(s); 412 return; 413 414 default: 415 /* 416 * Any unknown messages in this phase are ignored, 417 * and a failure message is returned. 418 */ 419 logit("Unknown packet type received after authentication: %d", type); 420 } 421 packet_start(success ? SSH_SMSG_SUCCESS : SSH_SMSG_FAILURE); 422 packet_send(); 423 packet_write_wait(); 424 425 /* Enable compression now that we have replied if appropriate. */ 426 if (enable_compression_after_reply) { 427 enable_compression_after_reply = 0; 428 packet_start_compression(compression_level); 429 } 430 } 431 } 432 433 #define USE_PIPES 434 /* 435 * This is called to fork and execute a command when we have no tty. This 436 * will call do_child from the child, and server_loop from the parent after 437 * setting up file descriptors and such. 438 */ 439 int 440 do_exec_no_pty(Session *s, const char *command) 441 { 442 pid_t pid; 443 444 #ifdef USE_PIPES 445 int pin[2], pout[2], perr[2]; 446 447 /* Allocate pipes for communicating with the program. */ 448 if (pipe(pin) < 0) { 449 error("%s: pipe in: %.100s", __func__, strerror(errno)); 450 return -1; 451 } 452 if (pipe(pout) < 0) { 453 error("%s: pipe out: %.100s", __func__, strerror(errno)); 454 close(pin[0]); 455 close(pin[1]); 456 return -1; 457 } 458 if (pipe(perr) < 0) { 459 error("%s: pipe err: %.100s", __func__, strerror(errno)); 460 close(pin[0]); 461 close(pin[1]); 462 close(pout[0]); 463 close(pout[1]); 464 return -1; 465 } 466 #else 467 int inout[2], err[2]; 468 469 /* Uses socket pairs to communicate with the program. */ 470 if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) < 0) { 471 error("%s: socketpair #1: %.100s", __func__, strerror(errno)); 472 return -1; 473 } 474 if (socketpair(AF_UNIX, SOCK_STREAM, 0, err) < 0) { 475 error("%s: socketpair #2: %.100s", __func__, strerror(errno)); 476 close(inout[0]); 477 close(inout[1]); 478 return -1; 479 } 480 #endif 481 482 if (s == NULL) 483 fatal("do_exec_no_pty: no session"); 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); 580 581 /* 582 * Clear loginmsg, since it's the child's responsibility to display 583 * it to the user, otherwise multiple sessions may accumulate 584 * multiple copies of the login messages. 585 */ 586 buffer_clear(&loginmsg); 587 588 #ifdef USE_PIPES 589 /* We are the parent. Close the child sides of the pipes. */ 590 close(pin[0]); 591 close(pout[1]); 592 close(perr[1]); 593 594 if (compat20) { 595 if (s->is_subsystem) { 596 close(perr[0]); 597 perr[0] = -1; 598 } 599 session_set_fds(s, pin[1], pout[0], perr[0], 0); 600 } else { 601 /* Enter the interactive session. */ 602 server_loop(pid, pin[1], pout[0], perr[0]); 603 /* server_loop has closed pin[1], pout[0], and perr[0]. */ 604 } 605 #else 606 /* We are the parent. Close the child sides of the socket pairs. */ 607 close(inout[0]); 608 close(err[0]); 609 610 /* 611 * Enter the interactive session. Note: server_loop must be able to 612 * handle the case that fdin and fdout are the same. 613 */ 614 if (compat20) { 615 session_set_fds(s, inout[1], inout[1], 616 s->is_subsystem ? -1 : err[1], 0); 617 if (s->is_subsystem) 618 close(err[1]); 619 } else { 620 server_loop(pid, inout[1], inout[1], err[1]); 621 /* server_loop has closed inout[1] and err[1]. */ 622 } 623 #endif 624 return 0; 625 } 626 627 /* 628 * This is called to fork and execute a command when we have a tty. This 629 * will call do_child from the child, and server_loop from the parent after 630 * setting up file descriptors, controlling tty, updating wtmp, utmp, 631 * lastlog, and other such operations. 632 */ 633 int 634 do_exec_pty(Session *s, const char *command) 635 { 636 int fdout, ptyfd, ttyfd, ptymaster; 637 pid_t pid; 638 639 if (s == NULL) 640 fatal("do_exec_pty: no session"); 641 ptyfd = s->ptyfd; 642 ttyfd = s->ttyfd; 643 644 /* 645 * Create another descriptor of the pty master side for use as the 646 * standard input. We could use the original descriptor, but this 647 * simplifies code in server_loop. The descriptor is bidirectional. 648 * Do this before forking (and cleanup in the child) so as to 649 * detect and gracefully fail out-of-fd conditions. 650 */ 651 if ((fdout = dup(ptyfd)) < 0) { 652 error("%s: dup #1: %s", __func__, strerror(errno)); 653 close(ttyfd); 654 close(ptyfd); 655 return -1; 656 } 657 /* we keep a reference to the pty master */ 658 if ((ptymaster = dup(ptyfd)) < 0) { 659 error("%s: dup #2: %s", __func__, strerror(errno)); 660 close(ttyfd); 661 close(ptyfd); 662 close(fdout); 663 return -1; 664 } 665 666 /* Fork the child. */ 667 switch ((pid = fork())) { 668 case -1: 669 error("%s: fork: %.100s", __func__, strerror(errno)); 670 close(fdout); 671 close(ptymaster); 672 close(ttyfd); 673 close(ptyfd); 674 return -1; 675 case 0: 676 is_child = 1; 677 678 close(fdout); 679 close(ptymaster); 680 681 /* Child. Reinitialize the log because the pid has changed. */ 682 log_init(__progname, options.log_level, 683 options.log_facility, log_stderr); 684 /* Close the master side of the pseudo tty. */ 685 close(ptyfd); 686 687 /* Make the pseudo tty our controlling tty. */ 688 pty_make_controlling_tty(&ttyfd, s->tty); 689 690 /* Redirect stdin/stdout/stderr from the pseudo tty. */ 691 if (dup2(ttyfd, 0) < 0) 692 error("dup2 stdin: %s", strerror(errno)); 693 if (dup2(ttyfd, 1) < 0) 694 error("dup2 stdout: %s", strerror(errno)); 695 if (dup2(ttyfd, 2) < 0) 696 error("dup2 stderr: %s", strerror(errno)); 697 698 /* Close the extra descriptor for the pseudo tty. */ 699 close(ttyfd); 700 701 /* record login, etc. similar to login(1) */ 702 #ifndef HAVE_OSF_SIA 703 if (!(options.use_login && command == NULL)) { 704 #ifdef _UNICOS 705 cray_init_job(s->pw); /* set up cray jid and tmpdir */ 706 #endif /* _UNICOS */ 707 do_login(s, command); 708 } 709 # ifdef LOGIN_NEEDS_UTMPX 710 else 711 do_pre_login(s); 712 # endif 713 #endif 714 /* 715 * Do common processing for the child, such as execing 716 * the command. 717 */ 718 do_child(s, command); 719 /* NOTREACHED */ 720 default: 721 break; 722 } 723 724 #ifdef _UNICOS 725 signal(WJSIGNAL, cray_job_termination_handler); 726 #endif /* _UNICOS */ 727 #ifdef HAVE_CYGWIN 728 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); 729 #endif 730 731 s->pid = pid; 732 733 /* Parent. Close the slave side of the pseudo tty. */ 734 close(ttyfd); 735 736 /* Enter interactive session. */ 737 s->ptymaster = ptymaster; 738 packet_set_interactive(1); 739 if (compat20) { 740 session_set_fds(s, ptyfd, fdout, -1, 1); 741 } else { 742 server_loop(pid, ptyfd, fdout, -1); 743 /* server_loop _has_ closed ptyfd and fdout. */ 744 } 745 return 0; 746 } 747 748 #ifdef LOGIN_NEEDS_UTMPX 749 static void 750 do_pre_login(Session *s) 751 { 752 socklen_t fromlen; 753 struct sockaddr_storage from; 754 pid_t pid = getpid(); 755 756 /* 757 * Get IP address of client. If the connection is not a socket, let 758 * the address be 0.0.0.0. 759 */ 760 memset(&from, 0, sizeof(from)); 761 fromlen = sizeof(from); 762 if (packet_connection_is_on_socket()) { 763 if (getpeername(packet_get_connection_in(), 764 (struct sockaddr *)&from, &fromlen) < 0) { 765 debug("getpeername: %.100s", strerror(errno)); 766 cleanup_exit(255); 767 } 768 } 769 770 record_utmp_only(pid, s->tty, s->pw->pw_name, 771 get_remote_name_or_ip(utmp_len, options.use_dns), 772 (struct sockaddr *)&from, fromlen); 773 } 774 #endif 775 776 /* 777 * This is called to fork and execute a command. If another command is 778 * to be forced, execute that instead. 779 */ 780 int 781 do_exec(Session *s, const char *command) 782 { 783 int ret; 784 785 if (options.adm_forced_command) { 786 original_command = command; 787 command = options.adm_forced_command; 788 if (IS_INTERNAL_SFTP(command)) 789 s->is_subsystem = SUBSYSTEM_INT_SFTP; 790 else if (s->is_subsystem) 791 s->is_subsystem = SUBSYSTEM_EXT; 792 debug("Forced command (config) '%.900s'", command); 793 } else if (forced_command) { 794 original_command = command; 795 command = forced_command; 796 if (IS_INTERNAL_SFTP(command)) 797 s->is_subsystem = SUBSYSTEM_INT_SFTP; 798 else if (s->is_subsystem) 799 s->is_subsystem = SUBSYSTEM_EXT; 800 debug("Forced command (key option) '%.900s'", command); 801 } 802 803 #ifdef SSH_AUDIT_EVENTS 804 if (command != NULL) 805 PRIVSEP(audit_run_command(command)); 806 else if (s->ttyfd == -1) { 807 char *shell = s->pw->pw_shell; 808 809 if (shell[0] == '\0') /* empty shell means /bin/sh */ 810 shell =_PATH_BSHELL; 811 PRIVSEP(audit_run_command(shell)); 812 } 813 #endif 814 if (s->ttyfd != -1) 815 ret = do_exec_pty(s, command); 816 else 817 ret = do_exec_no_pty(s, command); 818 819 original_command = NULL; 820 821 /* 822 * Clear loginmsg: it's the child's responsibility to display 823 * it to the user, otherwise multiple sessions may accumulate 824 * multiple copies of the login messages. 825 */ 826 buffer_clear(&loginmsg); 827 828 return ret; 829 } 830 831 /* administrative, login(1)-like work */ 832 void 833 do_login(Session *s, const char *command) 834 { 835 socklen_t fromlen; 836 struct sockaddr_storage from; 837 struct passwd * pw = s->pw; 838 pid_t pid = getpid(); 839 840 /* 841 * Get IP address of client. If the connection is not a socket, let 842 * the address be 0.0.0.0. 843 */ 844 memset(&from, 0, sizeof(from)); 845 fromlen = sizeof(from); 846 if (packet_connection_is_on_socket()) { 847 if (getpeername(packet_get_connection_in(), 848 (struct sockaddr *)&from, &fromlen) < 0) { 849 debug("getpeername: %.100s", strerror(errno)); 850 cleanup_exit(255); 851 } 852 } 853 854 /* Record that there was a login on that tty from the remote host. */ 855 if (!use_privsep) 856 record_login(pid, s->tty, pw->pw_name, pw->pw_uid, 857 get_remote_name_or_ip(utmp_len, 858 options.use_dns), 859 (struct sockaddr *)&from, fromlen); 860 861 #ifdef USE_PAM 862 /* 863 * If password change is needed, do it now. 864 * This needs to occur before the ~/.hushlogin check. 865 */ 866 if (options.use_pam && !use_privsep && s->authctxt->force_pwchange) { 867 display_loginmsg(); 868 do_pam_chauthtok(); 869 s->authctxt->force_pwchange = 0; 870 /* XXX - signal [net] parent to enable forwardings */ 871 } 872 #endif 873 874 if (check_quietlogin(s, command)) 875 return; 876 877 display_loginmsg(); 878 879 do_motd(); 880 } 881 882 /* 883 * Display the message of the day. 884 */ 885 void 886 do_motd(void) 887 { 888 FILE *f; 889 char buf[256]; 890 #ifdef HAVE_LOGIN_CAP 891 const char *fname; 892 #endif 893 894 #ifdef HAVE_LOGIN_CAP 895 fname = login_getcapstr(lc, "copyright", NULL, NULL); 896 if (fname != NULL && (f = fopen(fname, "r")) != NULL) { 897 while (fgets(buf, sizeof(buf), f) != NULL) 898 fputs(buf, stdout); 899 fclose(f); 900 } else 901 #endif /* HAVE_LOGIN_CAP */ 902 (void)printf("%s\n\t%s %s\n", 903 "Copyright (c) 1980, 1983, 1986, 1988, 1990, 1991, 1993, 1994", 904 "The Regents of the University of California. ", 905 "All rights reserved."); 906 907 (void)printf("\n"); 908 909 if (options.print_motd) { 910 #ifdef HAVE_LOGIN_CAP 911 f = fopen(login_getcapstr(lc, "welcome", "/etc/motd", 912 "/etc/motd"), "r"); 913 #else 914 f = fopen("/etc/motd", "r"); 915 #endif 916 if (f) { 917 while (fgets(buf, sizeof(buf), f)) 918 fputs(buf, stdout); 919 fclose(f); 920 } 921 } 922 } 923 924 925 /* 926 * Check for quiet login, either .hushlogin or command given. 927 */ 928 int 929 check_quietlogin(Session *s, const char *command) 930 { 931 char buf[256]; 932 struct passwd *pw = s->pw; 933 struct stat st; 934 935 /* Return 1 if .hushlogin exists or a command given. */ 936 if (command != NULL) 937 return 1; 938 snprintf(buf, sizeof(buf), "%.200s/.hushlogin", pw->pw_dir); 939 #ifdef HAVE_LOGIN_CAP 940 if (login_getcapbool(lc, "hushlogin", 0) || stat(buf, &st) >= 0) 941 return 1; 942 #else 943 if (stat(buf, &st) >= 0) 944 return 1; 945 #endif 946 return 0; 947 } 948 949 /* 950 * Sets the value of the given variable in the environment. If the variable 951 * already exists, its value is overridden. 952 */ 953 void 954 child_set_env(char ***envp, u_int *envsizep, const char *name, 955 const char *value) 956 { 957 char **env; 958 u_int envsize; 959 u_int i, namelen; 960 961 /* 962 * If we're passed an uninitialized list, allocate a single null 963 * entry before continuing. 964 */ 965 if (*envp == NULL && *envsizep == 0) { 966 *envp = xmalloc(sizeof(char *)); 967 *envp[0] = NULL; 968 *envsizep = 1; 969 } 970 971 /* 972 * Find the slot where the value should be stored. If the variable 973 * already exists, we reuse the slot; otherwise we append a new slot 974 * at the end of the array, expanding if necessary. 975 */ 976 env = *envp; 977 namelen = strlen(name); 978 for (i = 0; env[i]; i++) 979 if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=') 980 break; 981 if (env[i]) { 982 /* Reuse the slot. */ 983 xfree(env[i]); 984 } else { 985 /* New variable. Expand if necessary. */ 986 envsize = *envsizep; 987 if (i >= envsize - 1) { 988 if (envsize >= 1000) 989 fatal("child_set_env: too many env vars"); 990 envsize += 50; 991 env = (*envp) = xrealloc(env, envsize, sizeof(char *)); 992 *envsizep = envsize; 993 } 994 /* Need to set the NULL pointer at end of array beyond the new slot. */ 995 env[i + 1] = NULL; 996 } 997 998 /* Allocate space and format the variable in the appropriate slot. */ 999 env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1); 1000 snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value); 1001 } 1002 1003 /* 1004 * Reads environment variables from the given file and adds/overrides them 1005 * into the environment. If the file does not exist, this does nothing. 1006 * Otherwise, it must consist of empty lines, comments (line starts with '#') 1007 * and assignments of the form name=value. No other forms are allowed. 1008 */ 1009 static void 1010 read_environment_file(char ***env, u_int *envsize, 1011 const char *filename) 1012 { 1013 FILE *f; 1014 char buf[4096]; 1015 char *cp, *value; 1016 u_int lineno = 0; 1017 1018 f = fopen(filename, "r"); 1019 if (!f) 1020 return; 1021 1022 while (fgets(buf, sizeof(buf), f)) { 1023 if (++lineno > 1000) 1024 fatal("Too many lines in environment file %s", filename); 1025 for (cp = buf; *cp == ' ' || *cp == '\t'; cp++) 1026 ; 1027 if (!*cp || *cp == '#' || *cp == '\n') 1028 continue; 1029 1030 cp[strcspn(cp, "\n")] = '\0'; 1031 1032 value = strchr(cp, '='); 1033 if (value == NULL) { 1034 fprintf(stderr, "Bad line %u in %.100s\n", lineno, 1035 filename); 1036 continue; 1037 } 1038 /* 1039 * Replace the equals sign by nul, and advance value to 1040 * the value string. 1041 */ 1042 *value = '\0'; 1043 value++; 1044 child_set_env(env, envsize, cp, value); 1045 } 1046 fclose(f); 1047 } 1048 1049 #ifdef HAVE_ETC_DEFAULT_LOGIN 1050 /* 1051 * Return named variable from specified environment, or NULL if not present. 1052 */ 1053 static char * 1054 child_get_env(char **env, const char *name) 1055 { 1056 int i; 1057 size_t len; 1058 1059 len = strlen(name); 1060 for (i=0; env[i] != NULL; i++) 1061 if (strncmp(name, env[i], len) == 0 && env[i][len] == '=') 1062 return(env[i] + len + 1); 1063 return NULL; 1064 } 1065 1066 /* 1067 * Read /etc/default/login. 1068 * We pick up the PATH (or SUPATH for root) and UMASK. 1069 */ 1070 static void 1071 read_etc_default_login(char ***env, u_int *envsize, uid_t uid) 1072 { 1073 char **tmpenv = NULL, *var; 1074 u_int i, tmpenvsize = 0; 1075 u_long mask; 1076 1077 /* 1078 * We don't want to copy the whole file to the child's environment, 1079 * so we use a temporary environment and copy the variables we're 1080 * interested in. 1081 */ 1082 read_environment_file(&tmpenv, &tmpenvsize, "/etc/default/login"); 1083 1084 if (tmpenv == NULL) 1085 return; 1086 1087 if (uid == 0) 1088 var = child_get_env(tmpenv, "SUPATH"); 1089 else 1090 var = child_get_env(tmpenv, "PATH"); 1091 if (var != NULL) 1092 child_set_env(env, envsize, "PATH", var); 1093 1094 if ((var = child_get_env(tmpenv, "UMASK")) != NULL) 1095 if (sscanf(var, "%5lo", &mask) == 1) 1096 umask((mode_t)mask); 1097 1098 for (i = 0; tmpenv[i] != NULL; i++) 1099 xfree(tmpenv[i]); 1100 xfree(tmpenv); 1101 } 1102 #endif /* HAVE_ETC_DEFAULT_LOGIN */ 1103 1104 void 1105 copy_environment(char **source, char ***env, u_int *envsize) 1106 { 1107 char *var_name, *var_val; 1108 int i; 1109 1110 if (source == NULL) 1111 return; 1112 1113 for(i = 0; source[i] != NULL; i++) { 1114 var_name = xstrdup(source[i]); 1115 if ((var_val = strstr(var_name, "=")) == NULL) { 1116 xfree(var_name); 1117 continue; 1118 } 1119 *var_val++ = '\0'; 1120 1121 debug3("Copy environment: %s=%s", var_name, var_val); 1122 child_set_env(env, envsize, var_name, var_val); 1123 1124 xfree(var_name); 1125 } 1126 } 1127 1128 static char ** 1129 do_setup_env(Session *s, const char *shell) 1130 { 1131 char buf[256]; 1132 u_int i, envsize; 1133 char **env, *laddr; 1134 struct passwd *pw = s->pw; 1135 #if !defined (HAVE_LOGIN_CAP) && !defined (HAVE_CYGWIN) 1136 char *path = NULL; 1137 #else 1138 extern char **environ; 1139 char **senv, **var; 1140 #endif 1141 1142 /* Initialize the environment. */ 1143 envsize = 100; 1144 env = xcalloc(envsize, sizeof(char *)); 1145 env[0] = NULL; 1146 1147 #ifdef HAVE_CYGWIN 1148 /* 1149 * The Windows environment contains some setting which are 1150 * important for a running system. They must not be dropped. 1151 */ 1152 { 1153 char **p; 1154 1155 p = fetch_windows_environment(); 1156 copy_environment(p, &env, &envsize); 1157 free_windows_environment(p); 1158 } 1159 #endif 1160 1161 if (getenv("TZ")) 1162 child_set_env(&env, &envsize, "TZ", getenv("TZ")); 1163 1164 #ifdef GSSAPI 1165 /* Allow any GSSAPI methods that we've used to alter 1166 * the childs environment as they see fit 1167 */ 1168 ssh_gssapi_do_child(&env, &envsize); 1169 #endif 1170 1171 if (!options.use_login) { 1172 /* Set basic environment. */ 1173 for (i = 0; i < s->num_env; i++) 1174 child_set_env(&env, &envsize, s->env[i].name, 1175 s->env[i].val); 1176 1177 child_set_env(&env, &envsize, "USER", pw->pw_name); 1178 child_set_env(&env, &envsize, "LOGNAME", pw->pw_name); 1179 #ifdef _AIX 1180 child_set_env(&env, &envsize, "LOGIN", pw->pw_name); 1181 #endif 1182 child_set_env(&env, &envsize, "HOME", pw->pw_dir); 1183 snprintf(buf, sizeof buf, "%.200s/%.50s", 1184 _PATH_MAILDIR, pw->pw_name); 1185 child_set_env(&env, &envsize, "MAIL", buf); 1186 #ifdef HAVE_LOGIN_CAP 1187 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); 1188 child_set_env(&env, &envsize, "TERM", "su"); 1189 senv = environ; 1190 environ = xmalloc(sizeof(char *)); 1191 *environ = NULL; 1192 (void) setusercontext(lc, pw, pw->pw_uid, 1193 LOGIN_SETENV|LOGIN_SETPATH); 1194 copy_environment(environ, &env, &envsize); 1195 #if 0 1196 /* 1197 * This interferes with libc's management of the environment 1198 * in horrible ways that can cause sshd to crash. 1199 */ 1200 for (var = environ; *var != NULL; ++var) 1201 xfree(*var); 1202 xfree(environ); 1203 #endif 1204 environ = senv; 1205 #else /* HAVE_LOGIN_CAP */ 1206 # ifndef HAVE_CYGWIN 1207 /* 1208 * There's no standard path on Windows. The path contains 1209 * important components pointing to the system directories, 1210 * needed for loading shared libraries. So the path better 1211 * remains intact here. 1212 */ 1213 # ifdef HAVE_ETC_DEFAULT_LOGIN 1214 read_etc_default_login(&env, &envsize, pw->pw_uid); 1215 path = child_get_env(env, "PATH"); 1216 # endif /* HAVE_ETC_DEFAULT_LOGIN */ 1217 if (path == NULL || *path == '\0') { 1218 child_set_env(&env, &envsize, "PATH", 1219 s->pw->pw_uid == 0 ? 1220 SUPERUSER_PATH : _PATH_STDPATH); 1221 } 1222 # endif /* HAVE_CYGWIN */ 1223 #endif /* HAVE_LOGIN_CAP */ 1224 1225 /* Normal systems set SHELL by default. */ 1226 child_set_env(&env, &envsize, "SHELL", shell); 1227 } 1228 1229 /* Set custom environment options from RSA authentication. */ 1230 if (!options.use_login) { 1231 while (custom_environment) { 1232 struct envstring *ce = custom_environment; 1233 char *str = ce->s; 1234 1235 for (i = 0; str[i] != '=' && str[i]; i++) 1236 ; 1237 if (str[i] == '=') { 1238 str[i] = 0; 1239 child_set_env(&env, &envsize, str, str + i + 1); 1240 } 1241 custom_environment = ce->next; 1242 xfree(ce->s); 1243 xfree(ce); 1244 } 1245 } 1246 1247 /* SSH_CLIENT deprecated */ 1248 snprintf(buf, sizeof buf, "%.50s %d %d", 1249 get_remote_ipaddr(), get_remote_port(), get_local_port()); 1250 child_set_env(&env, &envsize, "SSH_CLIENT", buf); 1251 1252 laddr = get_local_ipaddr(packet_get_connection_in()); 1253 snprintf(buf, sizeof buf, "%.50s %d %.50s %d", 1254 get_remote_ipaddr(), get_remote_port(), laddr, get_local_port()); 1255 xfree(laddr); 1256 child_set_env(&env, &envsize, "SSH_CONNECTION", buf); 1257 1258 if (s->ttyfd != -1) 1259 child_set_env(&env, &envsize, "SSH_TTY", s->tty); 1260 if (s->term) 1261 child_set_env(&env, &envsize, "TERM", s->term); 1262 if (s->display) 1263 child_set_env(&env, &envsize, "DISPLAY", s->display); 1264 if (original_command) 1265 child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND", 1266 original_command); 1267 1268 #ifdef _UNICOS 1269 if (cray_tmpdir[0] != '\0') 1270 child_set_env(&env, &envsize, "TMPDIR", cray_tmpdir); 1271 #endif /* _UNICOS */ 1272 1273 /* 1274 * Since we clear KRB5CCNAME at startup, if it's set now then it 1275 * must have been set by a native authentication method (eg AIX or 1276 * SIA), so copy it to the child. 1277 */ 1278 { 1279 char *cp; 1280 1281 if ((cp = getenv("KRB5CCNAME")) != NULL) 1282 child_set_env(&env, &envsize, "KRB5CCNAME", cp); 1283 } 1284 1285 #ifdef _AIX 1286 { 1287 char *cp; 1288 1289 if ((cp = getenv("AUTHSTATE")) != NULL) 1290 child_set_env(&env, &envsize, "AUTHSTATE", cp); 1291 read_environment_file(&env, &envsize, "/etc/environment"); 1292 } 1293 #endif 1294 #ifdef KRB5 1295 if (s->authctxt->krb5_ccname) 1296 child_set_env(&env, &envsize, "KRB5CCNAME", 1297 s->authctxt->krb5_ccname); 1298 #endif 1299 #ifdef USE_PAM 1300 /* 1301 * Pull in any environment variables that may have 1302 * been set by PAM. 1303 */ 1304 if (options.use_pam) { 1305 char **p; 1306 1307 p = fetch_pam_child_environment(); 1308 copy_environment(p, &env, &envsize); 1309 free_pam_environment(p); 1310 1311 p = fetch_pam_environment(); 1312 copy_environment(p, &env, &envsize); 1313 free_pam_environment(p); 1314 } 1315 #endif /* USE_PAM */ 1316 1317 if (auth_sock_name != NULL) 1318 child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME, 1319 auth_sock_name); 1320 1321 /* read $HOME/.ssh/environment. */ 1322 if (options.permit_user_env && !options.use_login) { 1323 snprintf(buf, sizeof buf, "%.200s/.ssh/environment", 1324 strcmp(pw->pw_dir, "/") ? pw->pw_dir : ""); 1325 read_environment_file(&env, &envsize, buf); 1326 } 1327 if (debug_flag) { 1328 /* dump the environment */ 1329 fprintf(stderr, "Environment:\n"); 1330 for (i = 0; env[i]; i++) 1331 fprintf(stderr, " %.200s\n", env[i]); 1332 } 1333 return env; 1334 } 1335 1336 /* 1337 * Run $HOME/.ssh/rc, /etc/ssh/sshrc, or xauth (whichever is found 1338 * first in this order). 1339 */ 1340 static void 1341 do_rc_files(Session *s, const char *shell) 1342 { 1343 FILE *f = NULL; 1344 char cmd[1024]; 1345 int do_xauth; 1346 struct stat st; 1347 1348 do_xauth = 1349 s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL; 1350 1351 /* ignore _PATH_SSH_USER_RC for subsystems and admin forced commands */ 1352 if (!s->is_subsystem && options.adm_forced_command == NULL && 1353 !no_user_rc && stat(_PATH_SSH_USER_RC, &st) >= 0) { 1354 snprintf(cmd, sizeof cmd, "%s -c '%s %s'", 1355 shell, _PATH_BSHELL, _PATH_SSH_USER_RC); 1356 if (debug_flag) 1357 fprintf(stderr, "Running %s\n", cmd); 1358 f = popen(cmd, "w"); 1359 if (f) { 1360 if (do_xauth) 1361 fprintf(f, "%s %s\n", s->auth_proto, 1362 s->auth_data); 1363 pclose(f); 1364 } else 1365 fprintf(stderr, "Could not run %s\n", 1366 _PATH_SSH_USER_RC); 1367 } else if (stat(_PATH_SSH_SYSTEM_RC, &st) >= 0) { 1368 if (debug_flag) 1369 fprintf(stderr, "Running %s %s\n", _PATH_BSHELL, 1370 _PATH_SSH_SYSTEM_RC); 1371 f = popen(_PATH_BSHELL " " _PATH_SSH_SYSTEM_RC, "w"); 1372 if (f) { 1373 if (do_xauth) 1374 fprintf(f, "%s %s\n", s->auth_proto, 1375 s->auth_data); 1376 pclose(f); 1377 } else 1378 fprintf(stderr, "Could not run %s\n", 1379 _PATH_SSH_SYSTEM_RC); 1380 } else if (do_xauth && options.xauth_location != NULL) { 1381 /* Add authority data to .Xauthority if appropriate. */ 1382 if (debug_flag) { 1383 fprintf(stderr, 1384 "Running %.500s remove %.100s\n", 1385 options.xauth_location, s->auth_display); 1386 fprintf(stderr, 1387 "%.500s add %.100s %.100s %.100s\n", 1388 options.xauth_location, s->auth_display, 1389 s->auth_proto, s->auth_data); 1390 } 1391 snprintf(cmd, sizeof cmd, "%s -q -", 1392 options.xauth_location); 1393 f = popen(cmd, "w"); 1394 if (f) { 1395 fprintf(f, "remove %s\n", 1396 s->auth_display); 1397 fprintf(f, "add %s %s %s\n", 1398 s->auth_display, s->auth_proto, 1399 s->auth_data); 1400 pclose(f); 1401 } else { 1402 fprintf(stderr, "Could not run %s\n", 1403 cmd); 1404 } 1405 } 1406 } 1407 1408 static void 1409 do_nologin(struct passwd *pw) 1410 { 1411 FILE *f = NULL; 1412 char buf[1024]; 1413 1414 #ifdef HAVE_LOGIN_CAP 1415 if (!login_getcapbool(lc, "ignorenologin", 0) && pw->pw_uid) 1416 f = fopen(login_getcapstr(lc, "nologin", _PATH_NOLOGIN, 1417 _PATH_NOLOGIN), "r"); 1418 #else 1419 if (pw->pw_uid) 1420 f = fopen(_PATH_NOLOGIN, "r"); 1421 #endif 1422 if (f) { 1423 /* /etc/nologin exists. Print its contents and exit. */ 1424 logit("User %.100s not allowed because %s exists", 1425 pw->pw_name, _PATH_NOLOGIN); 1426 while (fgets(buf, sizeof(buf), f)) 1427 fputs(buf, stderr); 1428 fclose(f); 1429 fflush(NULL); 1430 exit(254); 1431 } 1432 } 1433 1434 /* 1435 * Chroot into a directory after checking it for safety: all path components 1436 * must be root-owned directories with strict permissions. 1437 */ 1438 static void 1439 safely_chroot(const char *path, uid_t uid) 1440 { 1441 const char *cp; 1442 char component[MAXPATHLEN]; 1443 struct stat st; 1444 1445 if (*path != '/') 1446 fatal("chroot path does not begin at root"); 1447 if (strlen(path) >= sizeof(component)) 1448 fatal("chroot path too long"); 1449 1450 /* 1451 * Descend the path, checking that each component is a 1452 * root-owned directory with strict permissions. 1453 */ 1454 for (cp = path; cp != NULL;) { 1455 if ((cp = strchr(cp, '/')) == NULL) 1456 strlcpy(component, path, sizeof(component)); 1457 else { 1458 cp++; 1459 memcpy(component, path, cp - path); 1460 component[cp - path] = '\0'; 1461 } 1462 1463 debug3("%s: checking '%s'", __func__, component); 1464 1465 if (stat(component, &st) != 0) 1466 fatal("%s: stat(\"%s\"): %s", __func__, 1467 component, strerror(errno)); 1468 if (st.st_uid != 0 || (st.st_mode & 022) != 0) 1469 fatal("bad ownership or modes for chroot " 1470 "directory %s\"%s\"", 1471 cp == NULL ? "" : "component ", component); 1472 if (!S_ISDIR(st.st_mode)) 1473 fatal("chroot path %s\"%s\" is not a directory", 1474 cp == NULL ? "" : "component ", component); 1475 1476 } 1477 1478 if (chdir(path) == -1) 1479 fatal("Unable to chdir to chroot path \"%s\": " 1480 "%s", path, strerror(errno)); 1481 if (chroot(path) == -1) 1482 fatal("chroot(\"%s\"): %s", path, strerror(errno)); 1483 if (chdir("/") == -1) 1484 fatal("%s: chdir(/) after chroot: %s", 1485 __func__, strerror(errno)); 1486 verbose("Changed root directory to \"%s\"", path); 1487 } 1488 1489 /* Set login name, uid, gid, and groups. */ 1490 void 1491 do_setusercontext(struct passwd *pw) 1492 { 1493 char *chroot_path, *tmp; 1494 1495 #ifdef WITH_SELINUX 1496 /* Cache selinux status for later use */ 1497 (void)ssh_selinux_enabled(); 1498 #endif 1499 1500 #ifndef HAVE_CYGWIN 1501 if (getuid() == 0 || geteuid() == 0) 1502 #endif /* HAVE_CYGWIN */ 1503 { 1504 #ifdef HAVE_LOGIN_CAP 1505 # ifdef __bsdi__ 1506 setpgid(0, 0); 1507 # endif 1508 # ifdef USE_PAM 1509 if (options.use_pam) { 1510 do_pam_setcred(use_privsep); 1511 } 1512 # endif /* USE_PAM */ 1513 if (setusercontext(lc, pw, pw->pw_uid, 1514 (LOGIN_SETALL & ~(LOGIN_SETPATH|LOGIN_SETUSER))) < 0) { 1515 perror("unable to set user context"); 1516 exit(1); 1517 } 1518 #else 1519 # if defined(HAVE_GETLUID) && defined(HAVE_SETLUID) 1520 /* Sets login uid for accounting */ 1521 if (getluid() == -1 && setluid(pw->pw_uid) == -1) 1522 error("setluid: %s", strerror(errno)); 1523 # endif /* defined(HAVE_GETLUID) && defined(HAVE_SETLUID) */ 1524 1525 if (setlogin(pw->pw_name) < 0) 1526 error("setlogin failed: %s", strerror(errno)); 1527 if (setgid(pw->pw_gid) < 0) { 1528 perror("setgid"); 1529 exit(1); 1530 } 1531 /* Initialize the group list. */ 1532 if (initgroups(pw->pw_name, pw->pw_gid) < 0) { 1533 perror("initgroups"); 1534 exit(1); 1535 } 1536 endgrent(); 1537 # ifdef USE_PAM 1538 /* 1539 * PAM credentials may take the form of supplementary groups. 1540 * These will have been wiped by the above initgroups() call. 1541 * Reestablish them here. 1542 */ 1543 if (options.use_pam) { 1544 do_pam_setcred(use_privsep); 1545 } 1546 # endif /* USE_PAM */ 1547 # if defined(WITH_IRIX_PROJECT) || defined(WITH_IRIX_JOBS) || defined(WITH_IRIX_ARRAY) 1548 irix_setusercontext(pw); 1549 # endif /* defined(WITH_IRIX_PROJECT) || defined(WITH_IRIX_JOBS) || defined(WITH_IRIX_ARRAY) */ 1550 # ifdef _AIX 1551 aix_usrinfo(pw); 1552 # endif /* _AIX */ 1553 # ifdef USE_LIBIAF 1554 if (set_id(pw->pw_name) != 0) { 1555 exit(1); 1556 } 1557 # endif /* USE_LIBIAF */ 1558 #endif 1559 1560 if (options.chroot_directory != NULL && 1561 strcasecmp(options.chroot_directory, "none") != 0) { 1562 tmp = tilde_expand_filename(options.chroot_directory, 1563 pw->pw_uid); 1564 chroot_path = percent_expand(tmp, "h", pw->pw_dir, 1565 "u", pw->pw_name, (char *)NULL); 1566 safely_chroot(chroot_path, pw->pw_uid); 1567 free(tmp); 1568 free(chroot_path); 1569 } 1570 1571 #ifdef HAVE_SETPCRED 1572 if (setpcred(pw->pw_name, (char **)NULL) == -1) 1573 fatal("Failed to set process credentials"); 1574 #endif /* HAVE_SETPCRED */ 1575 #ifdef HAVE_LOGIN_CAP 1576 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUSER) < 0) { 1577 perror("unable to set user context (setuser)"); 1578 exit(1); 1579 } 1580 #else 1581 /* Permanently switch to the desired uid. */ 1582 permanently_set_uid(pw); 1583 #endif 1584 } 1585 1586 if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) 1587 fatal("Failed to set uids to %u.", (u_int) pw->pw_uid); 1588 1589 #ifdef WITH_SELINUX 1590 ssh_selinux_setup_exec_context(pw->pw_name); 1591 #endif 1592 } 1593 1594 static void 1595 do_pwchange(Session *s) 1596 { 1597 fflush(NULL); 1598 fprintf(stderr, "WARNING: Your password has expired.\n"); 1599 if (s->ttyfd != -1) { 1600 fprintf(stderr, 1601 "You must change your password now and login again!\n"); 1602 #ifdef PASSWD_NEEDS_USERNAME 1603 execl(_PATH_PASSWD_PROG, "passwd", s->pw->pw_name, 1604 (char *)NULL); 1605 #else 1606 execl(_PATH_PASSWD_PROG, "passwd", (char *)NULL); 1607 #endif 1608 perror("passwd"); 1609 } else { 1610 fprintf(stderr, 1611 "Password change required but no TTY available.\n"); 1612 } 1613 exit(1); 1614 } 1615 1616 static void 1617 launch_login(struct passwd *pw, const char *hostname) 1618 { 1619 /* Launch login(1). */ 1620 1621 execl(LOGIN_PROGRAM, "login", "-h", hostname, 1622 #ifdef xxxLOGIN_NEEDS_TERM 1623 (s->term ? s->term : "unknown"), 1624 #endif /* LOGIN_NEEDS_TERM */ 1625 #ifdef LOGIN_NO_ENDOPT 1626 "-p", "-f", pw->pw_name, (char *)NULL); 1627 #else 1628 "-p", "-f", "--", pw->pw_name, (char *)NULL); 1629 #endif 1630 1631 /* Login couldn't be executed, die. */ 1632 1633 perror("login"); 1634 exit(1); 1635 } 1636 1637 static void 1638 child_close_fds(void) 1639 { 1640 int i; 1641 1642 if (packet_get_connection_in() == packet_get_connection_out()) 1643 close(packet_get_connection_in()); 1644 else { 1645 close(packet_get_connection_in()); 1646 close(packet_get_connection_out()); 1647 } 1648 /* 1649 * Close all descriptors related to channels. They will still remain 1650 * open in the parent. 1651 */ 1652 /* XXX better use close-on-exec? -markus */ 1653 channel_close_all(); 1654 1655 /* 1656 * Close any extra file descriptors. Note that there may still be 1657 * descriptors left by system functions. They will be closed later. 1658 */ 1659 endpwent(); 1660 1661 /* 1662 * Close any extra open file descriptors so that we don't have them 1663 * hanging around in clients. Note that we want to do this after 1664 * initgroups, because at least on Solaris 2.3 it leaves file 1665 * descriptors open. 1666 */ 1667 for (i = 3; i < 64; i++) 1668 close(i); 1669 } 1670 1671 /* 1672 * Performs common processing for the child, such as setting up the 1673 * environment, closing extra file descriptors, setting the user and group 1674 * ids, and executing the command or shell. 1675 */ 1676 #define ARGV_MAX 10 1677 void 1678 do_child(Session *s, const char *command) 1679 { 1680 extern char **environ; 1681 char **env; 1682 char *argv[ARGV_MAX]; 1683 const char *shell, *shell0, *hostname = NULL; 1684 struct passwd *pw = s->pw; 1685 int r = 0; 1686 1687 /* remove hostkey from the child's memory */ 1688 destroy_sensitive_data(); 1689 1690 /* Force a password change */ 1691 if (s->authctxt->force_pwchange) { 1692 do_setusercontext(pw); 1693 child_close_fds(); 1694 do_pwchange(s); 1695 exit(1); 1696 } 1697 1698 /* login(1) is only called if we execute the login shell */ 1699 if (options.use_login && command != NULL) 1700 options.use_login = 0; 1701 1702 #ifdef _UNICOS 1703 cray_setup(pw->pw_uid, pw->pw_name, command); 1704 #endif /* _UNICOS */ 1705 1706 /* 1707 * Login(1) does this as well, and it needs uid 0 for the "-h" 1708 * switch, so we let login(1) to this for us. 1709 */ 1710 if (!options.use_login) { 1711 #ifdef HAVE_OSF_SIA 1712 session_setup_sia(pw, s->ttyfd == -1 ? NULL : s->tty); 1713 if (!check_quietlogin(s, command)) 1714 do_motd(); 1715 #else /* HAVE_OSF_SIA */ 1716 /* When PAM is enabled we rely on it to do the nologin check */ 1717 if (!options.use_pam) 1718 do_nologin(pw); 1719 do_setusercontext(pw); 1720 /* 1721 * PAM session modules in do_setusercontext may have 1722 * generated messages, so if this in an interactive 1723 * login then display them too. 1724 */ 1725 if (!check_quietlogin(s, command)) 1726 display_loginmsg(); 1727 #endif /* HAVE_OSF_SIA */ 1728 } 1729 1730 #ifdef USE_PAM 1731 if (options.use_pam && !options.use_login && !is_pam_session_open()) { 1732 debug3("PAM session not opened, exiting"); 1733 display_loginmsg(); 1734 exit(254); 1735 } 1736 #endif 1737 1738 /* 1739 * Get the shell from the password data. An empty shell field is 1740 * legal, and means /bin/sh. 1741 */ 1742 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; 1743 1744 /* 1745 * Make sure $SHELL points to the shell from the password file, 1746 * even if shell is overridden from login.conf 1747 */ 1748 env = do_setup_env(s, shell); 1749 1750 #ifdef HAVE_LOGIN_CAP 1751 shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell); 1752 #endif 1753 1754 /* we have to stash the hostname before we close our socket. */ 1755 if (options.use_login) 1756 hostname = get_remote_name_or_ip(utmp_len, 1757 options.use_dns); 1758 /* 1759 * Close the connection descriptors; note that this is the child, and 1760 * the server will still have the socket open, and it is important 1761 * that we do not shutdown it. Note that the descriptors cannot be 1762 * closed before building the environment, as we call 1763 * get_remote_ipaddr there. 1764 */ 1765 child_close_fds(); 1766 1767 /* 1768 * Must take new environment into use so that .ssh/rc, 1769 * /etc/ssh/sshrc and xauth are run in the proper environment. 1770 */ 1771 environ = env; 1772 1773 #if defined(KRB5) && defined(USE_AFS) 1774 /* 1775 * At this point, we check to see if AFS is active and if we have 1776 * a valid Kerberos 5 TGT. If so, it seems like a good idea to see 1777 * if we can (and need to) extend the ticket into an AFS token. If 1778 * we don't do this, we run into potential problems if the user's 1779 * home directory is in AFS and it's not world-readable. 1780 */ 1781 1782 if (options.kerberos_get_afs_token && k_hasafs() && 1783 (s->authctxt->krb5_ctx != NULL)) { 1784 char cell[64]; 1785 1786 debug("Getting AFS token"); 1787 1788 k_setpag(); 1789 1790 if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0) 1791 krb5_afslog(s->authctxt->krb5_ctx, 1792 s->authctxt->krb5_fwd_ccache, cell, NULL); 1793 1794 krb5_afslog_home(s->authctxt->krb5_ctx, 1795 s->authctxt->krb5_fwd_ccache, NULL, NULL, pw->pw_dir); 1796 } 1797 #endif 1798 1799 /* Change current directory to the user's home directory. */ 1800 if (chdir(pw->pw_dir) < 0) { 1801 /* Suppress missing homedir warning for chroot case */ 1802 #ifdef HAVE_LOGIN_CAP 1803 r = login_getcapbool(lc, "requirehome", 0); 1804 #endif 1805 if (r || options.chroot_directory == NULL) 1806 fprintf(stderr, "Could not chdir to home " 1807 "directory %s: %s\n", pw->pw_dir, 1808 strerror(errno)); 1809 if (r) 1810 exit(1); 1811 } 1812 1813 closefrom(STDERR_FILENO + 1); 1814 1815 if (!options.use_login) 1816 do_rc_files(s, shell); 1817 1818 /* restore SIGPIPE for child */ 1819 signal(SIGPIPE, SIG_DFL); 1820 1821 if (s->is_subsystem == SUBSYSTEM_INT_SFTP) { 1822 extern int optind, optreset; 1823 int i; 1824 char *p, *args; 1825 1826 setproctitle("%s@%s", s->pw->pw_name, INTERNAL_SFTP_NAME); 1827 args = xstrdup(command ? command : "sftp-server"); 1828 for (i = 0, (p = strtok(args, " ")); p; (p = strtok(NULL, " "))) 1829 if (i < ARGV_MAX - 1) 1830 argv[i++] = p; 1831 argv[i] = NULL; 1832 optind = optreset = 1; 1833 __progname = argv[0]; 1834 exit(sftp_server_main(i, argv, s->pw)); 1835 } 1836 1837 if (options.use_login) { 1838 launch_login(pw, hostname); 1839 /* NEVERREACHED */ 1840 } 1841 1842 /* Get the last component of the shell name. */ 1843 if ((shell0 = strrchr(shell, '/')) != NULL) 1844 shell0++; 1845 else 1846 shell0 = shell; 1847 1848 /* 1849 * If we have no command, execute the shell. In this case, the shell 1850 * name to be passed in argv[0] is preceded by '-' to indicate that 1851 * this is a login shell. 1852 */ 1853 if (!command) { 1854 char argv0[256]; 1855 1856 /* Start the shell. Set initial character to '-'. */ 1857 argv0[0] = '-'; 1858 1859 if (strlcpy(argv0 + 1, shell0, sizeof(argv0) - 1) 1860 >= sizeof(argv0) - 1) { 1861 errno = EINVAL; 1862 perror(shell); 1863 exit(1); 1864 } 1865 1866 /* Execute the shell. */ 1867 argv[0] = argv0; 1868 argv[1] = NULL; 1869 execve(shell, argv, env); 1870 1871 /* Executing the shell failed. */ 1872 perror(shell); 1873 exit(1); 1874 } 1875 /* 1876 * Execute the command using the user's shell. This uses the -c 1877 * option to execute the command. 1878 */ 1879 argv[0] = (char *) shell0; 1880 argv[1] = "-c"; 1881 argv[2] = (char *) command; 1882 argv[3] = NULL; 1883 execve(shell, argv, env); 1884 perror(shell); 1885 exit(1); 1886 } 1887 1888 void 1889 session_unused(int id) 1890 { 1891 debug3("%s: session id %d unused", __func__, id); 1892 if (id >= options.max_sessions || 1893 id >= sessions_nalloc) { 1894 fatal("%s: insane session id %d (max %d nalloc %d)", 1895 __func__, id, options.max_sessions, sessions_nalloc); 1896 } 1897 bzero(&sessions[id], sizeof(*sessions)); 1898 sessions[id].self = id; 1899 sessions[id].used = 0; 1900 sessions[id].chanid = -1; 1901 sessions[id].ptyfd = -1; 1902 sessions[id].ttyfd = -1; 1903 sessions[id].ptymaster = -1; 1904 sessions[id].x11_chanids = NULL; 1905 sessions[id].next_unused = sessions_first_unused; 1906 sessions_first_unused = id; 1907 } 1908 1909 Session * 1910 session_new(void) 1911 { 1912 Session *s, *tmp; 1913 1914 if (sessions_first_unused == -1) { 1915 if (sessions_nalloc >= options.max_sessions) 1916 return NULL; 1917 debug2("%s: allocate (allocated %d max %d)", 1918 __func__, sessions_nalloc, options.max_sessions); 1919 tmp = xrealloc(sessions, sessions_nalloc + 1, 1920 sizeof(*sessions)); 1921 if (tmp == NULL) { 1922 error("%s: cannot allocate %d sessions", 1923 __func__, sessions_nalloc + 1); 1924 return NULL; 1925 } 1926 sessions = tmp; 1927 session_unused(sessions_nalloc++); 1928 } 1929 1930 if (sessions_first_unused >= sessions_nalloc || 1931 sessions_first_unused < 0) { 1932 fatal("%s: insane first_unused %d max %d nalloc %d", 1933 __func__, sessions_first_unused, options.max_sessions, 1934 sessions_nalloc); 1935 } 1936 1937 s = &sessions[sessions_first_unused]; 1938 if (s->used) { 1939 fatal("%s: session %d already used", 1940 __func__, sessions_first_unused); 1941 } 1942 sessions_first_unused = s->next_unused; 1943 s->used = 1; 1944 s->next_unused = -1; 1945 debug("session_new: session %d", s->self); 1946 1947 return s; 1948 } 1949 1950 static void 1951 session_dump(void) 1952 { 1953 int i; 1954 for (i = 0; i < sessions_nalloc; i++) { 1955 Session *s = &sessions[i]; 1956 1957 debug("dump: used %d next_unused %d session %d %p " 1958 "channel %d pid %ld", 1959 s->used, 1960 s->next_unused, 1961 s->self, 1962 s, 1963 s->chanid, 1964 (long)s->pid); 1965 } 1966 } 1967 1968 int 1969 session_open(Authctxt *authctxt, int chanid) 1970 { 1971 Session *s = session_new(); 1972 debug("session_open: channel %d", chanid); 1973 if (s == NULL) { 1974 error("no more sessions"); 1975 return 0; 1976 } 1977 s->authctxt = authctxt; 1978 s->pw = authctxt->pw; 1979 if (s->pw == NULL || !authctxt->valid) 1980 fatal("no user for session %d", s->self); 1981 debug("session_open: session %d: link with channel %d", s->self, chanid); 1982 s->chanid = chanid; 1983 return 1; 1984 } 1985 1986 Session * 1987 session_by_tty(char *tty) 1988 { 1989 int i; 1990 for (i = 0; i < sessions_nalloc; i++) { 1991 Session *s = &sessions[i]; 1992 if (s->used && s->ttyfd != -1 && strcmp(s->tty, tty) == 0) { 1993 debug("session_by_tty: session %d tty %s", i, tty); 1994 return s; 1995 } 1996 } 1997 debug("session_by_tty: unknown tty %.100s", tty); 1998 session_dump(); 1999 return NULL; 2000 } 2001 2002 static Session * 2003 session_by_channel(int id) 2004 { 2005 int i; 2006 for (i = 0; i < sessions_nalloc; i++) { 2007 Session *s = &sessions[i]; 2008 if (s->used && s->chanid == id) { 2009 debug("session_by_channel: session %d channel %d", 2010 i, id); 2011 return s; 2012 } 2013 } 2014 debug("session_by_channel: unknown channel %d", id); 2015 session_dump(); 2016 return NULL; 2017 } 2018 2019 static Session * 2020 session_by_x11_channel(int id) 2021 { 2022 int i, j; 2023 2024 for (i = 0; i < sessions_nalloc; i++) { 2025 Session *s = &sessions[i]; 2026 2027 if (s->x11_chanids == NULL || !s->used) 2028 continue; 2029 for (j = 0; s->x11_chanids[j] != -1; j++) { 2030 if (s->x11_chanids[j] == id) { 2031 debug("session_by_x11_channel: session %d " 2032 "channel %d", s->self, id); 2033 return s; 2034 } 2035 } 2036 } 2037 debug("session_by_x11_channel: unknown channel %d", id); 2038 session_dump(); 2039 return NULL; 2040 } 2041 2042 static Session * 2043 session_by_pid(pid_t pid) 2044 { 2045 int i; 2046 debug("session_by_pid: pid %ld", (long)pid); 2047 for (i = 0; i < sessions_nalloc; i++) { 2048 Session *s = &sessions[i]; 2049 if (s->used && s->pid == pid) 2050 return s; 2051 } 2052 error("session_by_pid: unknown pid %ld", (long)pid); 2053 session_dump(); 2054 return NULL; 2055 } 2056 2057 static int 2058 session_window_change_req(Session *s) 2059 { 2060 s->col = packet_get_int(); 2061 s->row = packet_get_int(); 2062 s->xpixel = packet_get_int(); 2063 s->ypixel = packet_get_int(); 2064 packet_check_eom(); 2065 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 2066 return 1; 2067 } 2068 2069 static int 2070 session_pty_req(Session *s) 2071 { 2072 u_int len; 2073 int n_bytes; 2074 2075 if (no_pty_flag) { 2076 debug("Allocating a pty not permitted for this authentication."); 2077 return 0; 2078 } 2079 if (s->ttyfd != -1) { 2080 packet_disconnect("Protocol error: you already have a pty."); 2081 return 0; 2082 } 2083 2084 s->term = packet_get_string(&len); 2085 2086 if (compat20) { 2087 s->col = packet_get_int(); 2088 s->row = packet_get_int(); 2089 } else { 2090 s->row = packet_get_int(); 2091 s->col = packet_get_int(); 2092 } 2093 s->xpixel = packet_get_int(); 2094 s->ypixel = packet_get_int(); 2095 2096 if (strcmp(s->term, "") == 0) { 2097 xfree(s->term); 2098 s->term = NULL; 2099 } 2100 2101 /* Allocate a pty and open it. */ 2102 debug("Allocating pty."); 2103 if (!PRIVSEP(pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, 2104 sizeof(s->tty)))) { 2105 if (s->term) 2106 xfree(s->term); 2107 s->term = NULL; 2108 s->ptyfd = -1; 2109 s->ttyfd = -1; 2110 error("session_pty_req: session %d alloc failed", s->self); 2111 return 0; 2112 } 2113 debug("session_pty_req: session %d alloc %s", s->self, s->tty); 2114 2115 /* for SSH1 the tty modes length is not given */ 2116 if (!compat20) 2117 n_bytes = packet_remaining(); 2118 tty_parse_modes(s->ttyfd, &n_bytes); 2119 2120 if (!use_privsep) 2121 pty_setowner(s->pw, s->tty); 2122 2123 /* Set window size from the packet. */ 2124 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 2125 2126 packet_check_eom(); 2127 session_proctitle(s); 2128 return 1; 2129 } 2130 2131 static int 2132 session_subsystem_req(Session *s) 2133 { 2134 struct stat st; 2135 u_int len; 2136 int success = 0; 2137 char *prog, *cmd, *subsys = packet_get_string(&len); 2138 u_int i; 2139 2140 packet_check_eom(); 2141 logit("subsystem request for %.100s", subsys); 2142 2143 for (i = 0; i < options.num_subsystems; i++) { 2144 if (strcmp(subsys, options.subsystem_name[i]) == 0) { 2145 prog = options.subsystem_command[i]; 2146 cmd = options.subsystem_args[i]; 2147 if (!strcmp(INTERNAL_SFTP_NAME, prog)) { 2148 s->is_subsystem = SUBSYSTEM_INT_SFTP; 2149 } else if (stat(prog, &st) < 0) { 2150 error("subsystem: cannot stat %s: %s", prog, 2151 strerror(errno)); 2152 break; 2153 } else { 2154 s->is_subsystem = SUBSYSTEM_EXT; 2155 } 2156 debug("subsystem: exec() %s", cmd); 2157 success = do_exec(s, cmd) == 0; 2158 break; 2159 } 2160 } 2161 2162 if (!success) 2163 logit("subsystem request for %.100s failed, subsystem not found", 2164 subsys); 2165 2166 xfree(subsys); 2167 return success; 2168 } 2169 2170 static int 2171 session_x11_req(Session *s) 2172 { 2173 int success; 2174 2175 if (s->auth_proto != NULL || s->auth_data != NULL) { 2176 error("session_x11_req: session %d: " 2177 "x11 forwarding already active", s->self); 2178 return 0; 2179 } 2180 s->single_connection = packet_get_char(); 2181 s->auth_proto = packet_get_string(NULL); 2182 s->auth_data = packet_get_string(NULL); 2183 s->screen = packet_get_int(); 2184 packet_check_eom(); 2185 2186 success = session_setup_x11fwd(s); 2187 if (!success) { 2188 xfree(s->auth_proto); 2189 xfree(s->auth_data); 2190 s->auth_proto = NULL; 2191 s->auth_data = NULL; 2192 } 2193 return success; 2194 } 2195 2196 static int 2197 session_shell_req(Session *s) 2198 { 2199 packet_check_eom(); 2200 return do_exec(s, NULL) == 0; 2201 } 2202 2203 static int 2204 session_exec_req(Session *s) 2205 { 2206 u_int len, success; 2207 2208 char *command = packet_get_string(&len); 2209 packet_check_eom(); 2210 success = do_exec(s, command) == 0; 2211 xfree(command); 2212 return success; 2213 } 2214 2215 static int 2216 session_break_req(Session *s) 2217 { 2218 2219 packet_get_int(); /* ignored */ 2220 packet_check_eom(); 2221 2222 if (s->ttyfd == -1 || tcsendbreak(s->ttyfd, 0) < 0) 2223 return 0; 2224 return 1; 2225 } 2226 2227 static int 2228 session_env_req(Session *s) 2229 { 2230 char *name, *val; 2231 u_int name_len, val_len, i; 2232 2233 name = packet_get_string(&name_len); 2234 val = packet_get_string(&val_len); 2235 packet_check_eom(); 2236 2237 /* Don't set too many environment variables */ 2238 if (s->num_env > 128) { 2239 debug2("Ignoring env request %s: too many env vars", name); 2240 goto fail; 2241 } 2242 2243 for (i = 0; i < options.num_accept_env; i++) { 2244 if (match_pattern(name, options.accept_env[i])) { 2245 debug2("Setting env %d: %s=%s", s->num_env, name, val); 2246 s->env = xrealloc(s->env, s->num_env + 1, 2247 sizeof(*s->env)); 2248 s->env[s->num_env].name = name; 2249 s->env[s->num_env].val = val; 2250 s->num_env++; 2251 return (1); 2252 } 2253 } 2254 debug2("Ignoring env request %s: disallowed name", name); 2255 2256 fail: 2257 xfree(name); 2258 xfree(val); 2259 return (0); 2260 } 2261 2262 static int 2263 session_auth_agent_req(Session *s) 2264 { 2265 static int called = 0; 2266 packet_check_eom(); 2267 if (no_agent_forwarding_flag || !options.allow_agent_forwarding) { 2268 debug("session_auth_agent_req: no_agent_forwarding_flag"); 2269 return 0; 2270 } 2271 if (called) { 2272 return 0; 2273 } else { 2274 called = 1; 2275 return auth_input_request_forwarding(s->pw); 2276 } 2277 } 2278 2279 int 2280 session_input_channel_req(Channel *c, const char *rtype) 2281 { 2282 int success = 0; 2283 Session *s; 2284 2285 if ((s = session_by_channel(c->self)) == NULL) { 2286 logit("session_input_channel_req: no session %d req %.100s", 2287 c->self, rtype); 2288 return 0; 2289 } 2290 debug("session_input_channel_req: session %d req %s", s->self, rtype); 2291 2292 /* 2293 * a session is in LARVAL state until a shell, a command 2294 * or a subsystem is executed 2295 */ 2296 if (c->type == SSH_CHANNEL_LARVAL) { 2297 if (strcmp(rtype, "shell") == 0) { 2298 success = session_shell_req(s); 2299 } else if (strcmp(rtype, "exec") == 0) { 2300 success = session_exec_req(s); 2301 } else if (strcmp(rtype, "pty-req") == 0) { 2302 success = session_pty_req(s); 2303 } else if (strcmp(rtype, "x11-req") == 0) { 2304 success = session_x11_req(s); 2305 } else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) { 2306 success = session_auth_agent_req(s); 2307 } else if (strcmp(rtype, "subsystem") == 0) { 2308 success = session_subsystem_req(s); 2309 } else if (strcmp(rtype, "env") == 0) { 2310 success = session_env_req(s); 2311 } 2312 } 2313 if (strcmp(rtype, "window-change") == 0) { 2314 success = session_window_change_req(s); 2315 } else if (strcmp(rtype, "break") == 0) { 2316 success = session_break_req(s); 2317 } 2318 2319 return success; 2320 } 2321 2322 void 2323 session_set_fds(Session *s, int fdin, int fdout, int fderr, int is_tty) 2324 { 2325 if (!compat20) 2326 fatal("session_set_fds: called for proto != 2.0"); 2327 /* 2328 * now that have a child and a pipe to the child, 2329 * we can activate our channel and register the fd's 2330 */ 2331 if (s->chanid == -1) 2332 fatal("no channel for session %d", s->self); 2333 channel_set_fds(s->chanid, 2334 fdout, fdin, fderr, 2335 fderr == -1 ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ, 2336 1, is_tty, CHAN_SES_WINDOW_DEFAULT); 2337 } 2338 2339 /* 2340 * Function to perform pty cleanup. Also called if we get aborted abnormally 2341 * (e.g., due to a dropped connection). 2342 */ 2343 void 2344 session_pty_cleanup2(Session *s) 2345 { 2346 if (s == NULL) { 2347 error("session_pty_cleanup: no session"); 2348 return; 2349 } 2350 if (s->ttyfd == -1) 2351 return; 2352 2353 debug("session_pty_cleanup: session %d release %s", s->self, s->tty); 2354 2355 /* Record that the user has logged out. */ 2356 if (s->pid != 0) 2357 record_logout(s->pid, s->tty, s->pw->pw_name); 2358 2359 /* Release the pseudo-tty. */ 2360 if (getuid() == 0) 2361 pty_release(s->tty); 2362 2363 /* 2364 * Close the server side of the socket pairs. We must do this after 2365 * the pty cleanup, so that another process doesn't get this pty 2366 * while we're still cleaning up. 2367 */ 2368 if (s->ptymaster != -1 && close(s->ptymaster) < 0) 2369 error("close(s->ptymaster/%d): %s", 2370 s->ptymaster, strerror(errno)); 2371 2372 /* unlink pty from session */ 2373 s->ttyfd = -1; 2374 } 2375 2376 void 2377 session_pty_cleanup(Session *s) 2378 { 2379 PRIVSEP(session_pty_cleanup2(s)); 2380 } 2381 2382 static char * 2383 sig2name(int sig) 2384 { 2385 #define SSH_SIG(x) if (sig == SIG ## x) return #x 2386 SSH_SIG(ABRT); 2387 SSH_SIG(ALRM); 2388 SSH_SIG(FPE); 2389 SSH_SIG(HUP); 2390 SSH_SIG(ILL); 2391 SSH_SIG(INT); 2392 SSH_SIG(KILL); 2393 SSH_SIG(PIPE); 2394 SSH_SIG(QUIT); 2395 SSH_SIG(SEGV); 2396 SSH_SIG(TERM); 2397 SSH_SIG(USR1); 2398 SSH_SIG(USR2); 2399 #undef SSH_SIG 2400 return "SIG@openssh.com"; 2401 } 2402 2403 static void 2404 session_close_x11(int id) 2405 { 2406 Channel *c; 2407 2408 if ((c = channel_by_id(id)) == NULL) { 2409 debug("session_close_x11: x11 channel %d missing", id); 2410 } else { 2411 /* Detach X11 listener */ 2412 debug("session_close_x11: detach x11 channel %d", id); 2413 channel_cancel_cleanup(id); 2414 if (c->ostate != CHAN_OUTPUT_CLOSED) 2415 chan_mark_dead(c); 2416 } 2417 } 2418 2419 static void 2420 session_close_single_x11(int id, void *arg) 2421 { 2422 Session *s; 2423 u_int i; 2424 2425 debug3("session_close_single_x11: channel %d", id); 2426 channel_cancel_cleanup(id); 2427 if ((s = session_by_x11_channel(id)) == NULL) 2428 fatal("session_close_single_x11: no x11 channel %d", id); 2429 for (i = 0; s->x11_chanids[i] != -1; i++) { 2430 debug("session_close_single_x11: session %d: " 2431 "closing channel %d", s->self, s->x11_chanids[i]); 2432 /* 2433 * The channel "id" is already closing, but make sure we 2434 * close all of its siblings. 2435 */ 2436 if (s->x11_chanids[i] != id) 2437 session_close_x11(s->x11_chanids[i]); 2438 } 2439 xfree(s->x11_chanids); 2440 s->x11_chanids = NULL; 2441 if (s->display) { 2442 xfree(s->display); 2443 s->display = NULL; 2444 } 2445 if (s->auth_proto) { 2446 xfree(s->auth_proto); 2447 s->auth_proto = NULL; 2448 } 2449 if (s->auth_data) { 2450 xfree(s->auth_data); 2451 s->auth_data = NULL; 2452 } 2453 if (s->auth_display) { 2454 xfree(s->auth_display); 2455 s->auth_display = NULL; 2456 } 2457 } 2458 2459 static void 2460 session_exit_message(Session *s, int status) 2461 { 2462 Channel *c; 2463 2464 if ((c = channel_lookup(s->chanid)) == NULL) 2465 fatal("session_exit_message: session %d: no channel %d", 2466 s->self, s->chanid); 2467 debug("session_exit_message: session %d channel %d pid %ld", 2468 s->self, s->chanid, (long)s->pid); 2469 2470 if (WIFEXITED(status)) { 2471 channel_request_start(s->chanid, "exit-status", 0); 2472 packet_put_int(WEXITSTATUS(status)); 2473 packet_send(); 2474 } else if (WIFSIGNALED(status)) { 2475 channel_request_start(s->chanid, "exit-signal", 0); 2476 packet_put_cstring(sig2name(WTERMSIG(status))); 2477 #ifdef WCOREDUMP 2478 packet_put_char(WCOREDUMP(status)? 1 : 0); 2479 #else /* WCOREDUMP */ 2480 packet_put_char(0); 2481 #endif /* WCOREDUMP */ 2482 packet_put_cstring(""); 2483 packet_put_cstring(""); 2484 packet_send(); 2485 } else { 2486 /* Some weird exit cause. Just exit. */ 2487 packet_disconnect("wait returned status %04x.", status); 2488 } 2489 2490 /* disconnect channel */ 2491 debug("session_exit_message: release channel %d", s->chanid); 2492 2493 /* 2494 * Adjust cleanup callback attachment to send close messages when 2495 * the channel gets EOF. The session will be then be closed 2496 * by session_close_by_channel when the childs close their fds. 2497 */ 2498 channel_register_cleanup(c->self, session_close_by_channel, 1); 2499 2500 /* 2501 * emulate a write failure with 'chan_write_failed', nobody will be 2502 * interested in data we write. 2503 * Note that we must not call 'chan_read_failed', since there could 2504 * be some more data waiting in the pipe. 2505 */ 2506 if (c->ostate != CHAN_OUTPUT_CLOSED) 2507 chan_write_failed(c); 2508 } 2509 2510 void 2511 session_close(Session *s) 2512 { 2513 u_int i; 2514 2515 debug("session_close: session %d pid %ld", s->self, (long)s->pid); 2516 if (s->ttyfd != -1) 2517 session_pty_cleanup(s); 2518 if (s->term) 2519 xfree(s->term); 2520 if (s->display) 2521 xfree(s->display); 2522 if (s->x11_chanids) 2523 xfree(s->x11_chanids); 2524 if (s->auth_display) 2525 xfree(s->auth_display); 2526 if (s->auth_data) 2527 xfree(s->auth_data); 2528 if (s->auth_proto) 2529 xfree(s->auth_proto); 2530 if (s->env != NULL) { 2531 for (i = 0; i < s->num_env; i++) { 2532 xfree(s->env[i].name); 2533 xfree(s->env[i].val); 2534 } 2535 xfree(s->env); 2536 } 2537 session_proctitle(s); 2538 session_unused(s->self); 2539 } 2540 2541 void 2542 session_close_by_pid(pid_t pid, int status) 2543 { 2544 Session *s = session_by_pid(pid); 2545 if (s == NULL) { 2546 debug("session_close_by_pid: no session for pid %ld", 2547 (long)pid); 2548 return; 2549 } 2550 if (s->chanid != -1) 2551 session_exit_message(s, status); 2552 if (s->ttyfd != -1) 2553 session_pty_cleanup(s); 2554 s->pid = 0; 2555 } 2556 2557 /* 2558 * this is called when a channel dies before 2559 * the session 'child' itself dies 2560 */ 2561 void 2562 session_close_by_channel(int id, void *arg) 2563 { 2564 Session *s = session_by_channel(id); 2565 u_int i; 2566 2567 if (s == NULL) { 2568 debug("session_close_by_channel: no session for id %d", id); 2569 return; 2570 } 2571 debug("session_close_by_channel: channel %d child %ld", 2572 id, (long)s->pid); 2573 if (s->pid != 0) { 2574 debug("session_close_by_channel: channel %d: has child", id); 2575 /* 2576 * delay detach of session, but release pty, since 2577 * the fd's to the child are already closed 2578 */ 2579 if (s->ttyfd != -1) 2580 session_pty_cleanup(s); 2581 return; 2582 } 2583 /* detach by removing callback */ 2584 channel_cancel_cleanup(s->chanid); 2585 2586 /* Close any X11 listeners associated with this session */ 2587 if (s->x11_chanids != NULL) { 2588 for (i = 0; s->x11_chanids[i] != -1; i++) { 2589 session_close_x11(s->x11_chanids[i]); 2590 s->x11_chanids[i] = -1; 2591 } 2592 } 2593 2594 s->chanid = -1; 2595 session_close(s); 2596 } 2597 2598 void 2599 session_destroy_all(void (*closefunc)(Session *)) 2600 { 2601 int i; 2602 for (i = 0; i < sessions_nalloc; i++) { 2603 Session *s = &sessions[i]; 2604 if (s->used) { 2605 if (closefunc != NULL) 2606 closefunc(s); 2607 else 2608 session_close(s); 2609 } 2610 } 2611 } 2612 2613 static char * 2614 session_tty_list(void) 2615 { 2616 static char buf[1024]; 2617 int i; 2618 char *cp; 2619 2620 buf[0] = '\0'; 2621 for (i = 0; i < sessions_nalloc; i++) { 2622 Session *s = &sessions[i]; 2623 if (s->used && s->ttyfd != -1) { 2624 2625 if (strncmp(s->tty, "/dev/", 5) != 0) { 2626 cp = strrchr(s->tty, '/'); 2627 cp = (cp == NULL) ? s->tty : cp + 1; 2628 } else 2629 cp = s->tty + 5; 2630 2631 if (buf[0] != '\0') 2632 strlcat(buf, ",", sizeof buf); 2633 strlcat(buf, cp, sizeof buf); 2634 } 2635 } 2636 if (buf[0] == '\0') 2637 strlcpy(buf, "notty", sizeof buf); 2638 return buf; 2639 } 2640 2641 void 2642 session_proctitle(Session *s) 2643 { 2644 if (s->pw == NULL) 2645 error("no user for session %d", s->self); 2646 else 2647 setproctitle("%s@%s", s->pw->pw_name, session_tty_list()); 2648 } 2649 2650 int 2651 session_setup_x11fwd(Session *s) 2652 { 2653 struct stat st; 2654 char display[512], auth_display[512]; 2655 char hostname[MAXHOSTNAMELEN]; 2656 u_int i; 2657 2658 if (no_x11_forwarding_flag) { 2659 packet_send_debug("X11 forwarding disabled in user configuration file."); 2660 return 0; 2661 } 2662 if (!options.x11_forwarding) { 2663 debug("X11 forwarding disabled in server configuration file."); 2664 return 0; 2665 } 2666 if (!options.xauth_location || 2667 (stat(options.xauth_location, &st) == -1)) { 2668 packet_send_debug("No xauth program; cannot forward with spoofing."); 2669 return 0; 2670 } 2671 if (options.use_login) { 2672 packet_send_debug("X11 forwarding disabled; " 2673 "not compatible with UseLogin=yes."); 2674 return 0; 2675 } 2676 if (s->display != NULL) { 2677 debug("X11 display already set."); 2678 return 0; 2679 } 2680 if (x11_create_display_inet(options.x11_display_offset, 2681 options.x11_use_localhost, s->single_connection, 2682 &s->display_number, &s->x11_chanids) == -1) { 2683 debug("x11_create_display_inet failed."); 2684 return 0; 2685 } 2686 for (i = 0; s->x11_chanids[i] != -1; i++) { 2687 channel_register_cleanup(s->x11_chanids[i], 2688 session_close_single_x11, 0); 2689 } 2690 2691 /* Set up a suitable value for the DISPLAY variable. */ 2692 if (gethostname(hostname, sizeof(hostname)) < 0) 2693 fatal("gethostname: %.100s", strerror(errno)); 2694 /* 2695 * auth_display must be used as the displayname when the 2696 * authorization entry is added with xauth(1). This will be 2697 * different than the DISPLAY string for localhost displays. 2698 */ 2699 if (options.x11_use_localhost) { 2700 snprintf(display, sizeof display, "localhost:%u.%u", 2701 s->display_number, s->screen); 2702 snprintf(auth_display, sizeof auth_display, "unix:%u.%u", 2703 s->display_number, s->screen); 2704 s->display = xstrdup(display); 2705 s->auth_display = xstrdup(auth_display); 2706 } else { 2707 #ifdef IPADDR_IN_DISPLAY 2708 struct hostent *he; 2709 struct in_addr my_addr; 2710 2711 he = gethostbyname(hostname); 2712 if (he == NULL) { 2713 error("Can't get IP address for X11 DISPLAY."); 2714 packet_send_debug("Can't get IP address for X11 DISPLAY."); 2715 return 0; 2716 } 2717 memcpy(&my_addr, he->h_addr_list[0], sizeof(struct in_addr)); 2718 snprintf(display, sizeof display, "%.50s:%u.%u", inet_ntoa(my_addr), 2719 s->display_number, s->screen); 2720 #else 2721 snprintf(display, sizeof display, "%.400s:%u.%u", hostname, 2722 s->display_number, s->screen); 2723 #endif 2724 s->display = xstrdup(display); 2725 s->auth_display = xstrdup(display); 2726 } 2727 2728 return 1; 2729 } 2730 2731 static void 2732 do_authenticated2(Authctxt *authctxt) 2733 { 2734 server_loop2(authctxt); 2735 } 2736 2737 void 2738 do_cleanup(Authctxt *authctxt) 2739 { 2740 static int called = 0; 2741 2742 debug("do_cleanup"); 2743 2744 /* no cleanup if we're in the child for login shell */ 2745 if (is_child) 2746 return; 2747 2748 /* avoid double cleanup */ 2749 if (called) 2750 return; 2751 called = 1; 2752 2753 if (authctxt == NULL) 2754 return; 2755 2756 #ifdef USE_PAM 2757 if (options.use_pam) { 2758 sshpam_cleanup(); 2759 sshpam_thread_cleanup(); 2760 } 2761 #endif 2762 2763 if (!authctxt->authenticated) 2764 return; 2765 2766 #ifdef KRB5 2767 if (options.kerberos_ticket_cleanup && 2768 authctxt->krb5_ctx) 2769 krb5_cleanup_proc(authctxt); 2770 #endif 2771 2772 #ifdef GSSAPI 2773 if (compat20 && options.gss_cleanup_creds) 2774 ssh_gssapi_cleanup_creds(); 2775 #endif 2776 2777 /* remove agent socket */ 2778 auth_sock_cleanup_proc(authctxt->pw); 2779 2780 /* 2781 * Cleanup ptys/utmp only if privsep is disabled, 2782 * or if running in monitor. 2783 */ 2784 if (!use_privsep || mm_is_monitor()) 2785 session_destroy_all(session_pty_cleanup2); 2786 } 2787