1 /* $OpenBSD: session.c,v 1.274 2014/07/15 15:54:14 millert 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 <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 64 #include "openbsd-compat/sys-queue.h" 65 #include "xmalloc.h" 66 #include "ssh.h" 67 #include "ssh1.h" 68 #include "ssh2.h" 69 #include "sshpty.h" 70 #include "packet.h" 71 #include "buffer.h" 72 #include "match.h" 73 #include "uidswap.h" 74 #include "compat.h" 75 #include "channels.h" 76 #include "key.h" 77 #include "cipher.h" 78 #ifdef GSSAPI 79 #include "ssh-gss.h" 80 #endif 81 #include "hostfile.h" 82 #include "auth.h" 83 #include "auth-options.h" 84 #include "authfd.h" 85 #include "pathnames.h" 86 #include "log.h" 87 #include "misc.h" 88 #include "servconf.h" 89 #include "sshlogin.h" 90 #include "serverloop.h" 91 #include "canohost.h" 92 #include "session.h" 93 #include "kex.h" 94 #include "monitor_wrap.h" 95 #include "sftp.h" 96 97 #if defined(KRB5) && defined(USE_AFS) 98 #include <kafs.h> 99 #endif 100 101 #ifdef WITH_SELINUX 102 #include <selinux/selinux.h> 103 #endif 104 105 #define IS_INTERNAL_SFTP(c) \ 106 (!strncmp(c, INTERNAL_SFTP_NAME, sizeof(INTERNAL_SFTP_NAME) - 1) && \ 107 (c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\0' || \ 108 c[sizeof(INTERNAL_SFTP_NAME) - 1] == ' ' || \ 109 c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\t')) 110 111 /* func */ 112 113 Session *session_new(void); 114 void session_set_fds(Session *, int, int, int, int, int); 115 void session_pty_cleanup(Session *); 116 void session_proctitle(Session *); 117 int session_setup_x11fwd(Session *); 118 int do_exec_pty(Session *, const char *); 119 int do_exec_no_pty(Session *, const char *); 120 int do_exec(Session *, const char *); 121 void do_login(Session *, const char *); 122 #ifdef LOGIN_NEEDS_UTMPX 123 static void do_pre_login(Session *s); 124 #endif 125 void do_child(Session *, const char *); 126 void do_motd(void); 127 int check_quietlogin(Session *, const char *); 128 129 static void do_authenticated1(Authctxt *); 130 static void do_authenticated2(Authctxt *); 131 132 static int session_pty_req(Session *); 133 134 /* import */ 135 extern ServerOptions options; 136 extern char *__progname; 137 extern int log_stderr; 138 extern int debug_flag; 139 extern u_int utmp_len; 140 extern int startup_pipe; 141 extern void destroy_sensitive_data(void); 142 extern Buffer loginmsg; 143 144 /* original command from peer. */ 145 const char *original_command = NULL; 146 147 /* data */ 148 static int sessions_first_unused = -1; 149 static int sessions_nalloc = 0; 150 static Session *sessions = NULL; 151 152 #define SUBSYSTEM_NONE 0 153 #define SUBSYSTEM_EXT 1 154 #define SUBSYSTEM_INT_SFTP 2 155 #define SUBSYSTEM_INT_SFTP_ERROR 3 156 157 #ifdef HAVE_LOGIN_CAP 158 login_cap_t *lc; 159 #endif 160 161 static int is_child = 0; 162 163 /* Name and directory of socket for authentication agent forwarding. */ 164 static char *auth_sock_name = NULL; 165 static char *auth_sock_dir = NULL; 166 167 /* removes the agent forwarding socket */ 168 169 static void 170 auth_sock_cleanup_proc(struct passwd *pw) 171 { 172 if (auth_sock_name != NULL) { 173 temporarily_use_uid(pw); 174 unlink(auth_sock_name); 175 rmdir(auth_sock_dir); 176 auth_sock_name = NULL; 177 restore_uid(); 178 } 179 } 180 181 static int 182 auth_input_request_forwarding(struct passwd * pw) 183 { 184 Channel *nc; 185 int sock = -1; 186 187 if (auth_sock_name != NULL) { 188 error("authentication forwarding requested twice."); 189 return 0; 190 } 191 192 /* Temporarily drop privileged uid for mkdir/bind. */ 193 temporarily_use_uid(pw); 194 195 /* Allocate a buffer for the socket name, and format the name. */ 196 auth_sock_dir = xstrdup("/tmp/ssh-XXXXXXXXXX"); 197 198 /* Create private directory for socket */ 199 if (mkdtemp(auth_sock_dir) == NULL) { 200 packet_send_debug("Agent forwarding disabled: " 201 "mkdtemp() failed: %.100s", strerror(errno)); 202 restore_uid(); 203 free(auth_sock_dir); 204 auth_sock_dir = NULL; 205 goto authsock_err; 206 } 207 208 xasprintf(&auth_sock_name, "%s/agent.%ld", 209 auth_sock_dir, (long) getpid()); 210 211 /* Start a Unix listener on auth_sock_name. */ 212 sock = unix_listener(auth_sock_name, SSH_LISTEN_BACKLOG, 0); 213 214 /* Restore the privileged uid. */ 215 restore_uid(); 216 217 /* Check for socket/bind/listen failure. */ 218 if (sock < 0) 219 goto authsock_err; 220 221 /* Allocate a channel for the authentication agent socket. */ 222 /* this shouldn't matter if its hpn or not - cjr */ 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 #ifdef HAVE_LOGIN_CAP 913 const char *fname; 914 #endif 915 916 #ifdef HAVE_LOGIN_CAP 917 fname = login_getcapstr(lc, "copyright", NULL, NULL); 918 if (fname != NULL && (f = fopen(fname, "r")) != NULL) { 919 while (fgets(buf, sizeof(buf), f) != NULL) 920 fputs(buf, stdout); 921 fclose(f); 922 } else 923 #endif /* HAVE_LOGIN_CAP */ 924 (void)printf("%s\n\t%s %s\n", 925 "Copyright (c) 1980, 1983, 1986, 1988, 1990, 1991, 1993, 1994", 926 "The Regents of the University of California. ", 927 "All rights reserved."); 928 929 (void)printf("\n"); 930 931 if (options.print_motd) { 932 #ifdef HAVE_LOGIN_CAP 933 f = fopen(login_getcapstr(lc, "welcome", "/etc/motd", 934 "/etc/motd"), "r"); 935 #else 936 f = fopen("/etc/motd", "r"); 937 #endif 938 if (f) { 939 while (fgets(buf, sizeof(buf), f)) 940 fputs(buf, stdout); 941 fclose(f); 942 } 943 } 944 } 945 946 947 /* 948 * Check for quiet login, either .hushlogin or command given. 949 */ 950 int 951 check_quietlogin(Session *s, const char *command) 952 { 953 char buf[256]; 954 struct passwd *pw = s->pw; 955 struct stat st; 956 957 /* Return 1 if .hushlogin exists or a command given. */ 958 if (command != NULL) 959 return 1; 960 snprintf(buf, sizeof(buf), "%.200s/.hushlogin", pw->pw_dir); 961 #ifdef HAVE_LOGIN_CAP 962 if (login_getcapbool(lc, "hushlogin", 0) || stat(buf, &st) >= 0) 963 return 1; 964 #else 965 if (stat(buf, &st) >= 0) 966 return 1; 967 #endif 968 return 0; 969 } 970 971 /* 972 * Sets the value of the given variable in the environment. If the variable 973 * already exists, its value is overridden. 974 */ 975 void 976 child_set_env(char ***envp, u_int *envsizep, const char *name, 977 const char *value) 978 { 979 char **env; 980 u_int envsize; 981 u_int i, namelen; 982 983 if (strchr(name, '=') != NULL) { 984 error("Invalid environment variable \"%.100s\"", name); 985 return; 986 } 987 988 /* 989 * If we're passed an uninitialized list, allocate a single null 990 * entry before continuing. 991 */ 992 if (*envp == NULL && *envsizep == 0) { 993 *envp = xmalloc(sizeof(char *)); 994 *envp[0] = NULL; 995 *envsizep = 1; 996 } 997 998 /* 999 * Find the slot where the value should be stored. If the variable 1000 * already exists, we reuse the slot; otherwise we append a new slot 1001 * at the end of the array, expanding if necessary. 1002 */ 1003 env = *envp; 1004 namelen = strlen(name); 1005 for (i = 0; env[i]; i++) 1006 if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=') 1007 break; 1008 if (env[i]) { 1009 /* Reuse the slot. */ 1010 free(env[i]); 1011 } else { 1012 /* New variable. Expand if necessary. */ 1013 envsize = *envsizep; 1014 if (i >= envsize - 1) { 1015 if (envsize >= 1000) 1016 fatal("child_set_env: too many env vars"); 1017 envsize += 50; 1018 env = (*envp) = xrealloc(env, envsize, sizeof(char *)); 1019 *envsizep = envsize; 1020 } 1021 /* Need to set the NULL pointer at end of array beyond the new slot. */ 1022 env[i + 1] = NULL; 1023 } 1024 1025 /* Allocate space and format the variable in the appropriate slot. */ 1026 env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1); 1027 snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value); 1028 } 1029 1030 /* 1031 * Reads environment variables from the given file and adds/overrides them 1032 * into the environment. If the file does not exist, this does nothing. 1033 * Otherwise, it must consist of empty lines, comments (line starts with '#') 1034 * and assignments of the form name=value. No other forms are allowed. 1035 */ 1036 static void 1037 read_environment_file(char ***env, u_int *envsize, 1038 const char *filename) 1039 { 1040 FILE *f; 1041 char buf[4096]; 1042 char *cp, *value; 1043 u_int lineno = 0; 1044 1045 f = fopen(filename, "r"); 1046 if (!f) 1047 return; 1048 1049 while (fgets(buf, sizeof(buf), f)) { 1050 if (++lineno > 1000) 1051 fatal("Too many lines in environment file %s", filename); 1052 for (cp = buf; *cp == ' ' || *cp == '\t'; cp++) 1053 ; 1054 if (!*cp || *cp == '#' || *cp == '\n') 1055 continue; 1056 1057 cp[strcspn(cp, "\n")] = '\0'; 1058 1059 value = strchr(cp, '='); 1060 if (value == NULL) { 1061 fprintf(stderr, "Bad line %u in %.100s\n", lineno, 1062 filename); 1063 continue; 1064 } 1065 /* 1066 * Replace the equals sign by nul, and advance value to 1067 * the value string. 1068 */ 1069 *value = '\0'; 1070 value++; 1071 child_set_env(env, envsize, cp, value); 1072 } 1073 fclose(f); 1074 } 1075 1076 #ifdef HAVE_ETC_DEFAULT_LOGIN 1077 /* 1078 * Return named variable from specified environment, or NULL if not present. 1079 */ 1080 static char * 1081 child_get_env(char **env, const char *name) 1082 { 1083 int i; 1084 size_t len; 1085 1086 len = strlen(name); 1087 for (i=0; env[i] != NULL; i++) 1088 if (strncmp(name, env[i], len) == 0 && env[i][len] == '=') 1089 return(env[i] + len + 1); 1090 return NULL; 1091 } 1092 1093 /* 1094 * Read /etc/default/login. 1095 * We pick up the PATH (or SUPATH for root) and UMASK. 1096 */ 1097 static void 1098 read_etc_default_login(char ***env, u_int *envsize, uid_t uid) 1099 { 1100 char **tmpenv = NULL, *var; 1101 u_int i, tmpenvsize = 0; 1102 u_long mask; 1103 1104 /* 1105 * We don't want to copy the whole file to the child's environment, 1106 * so we use a temporary environment and copy the variables we're 1107 * interested in. 1108 */ 1109 read_environment_file(&tmpenv, &tmpenvsize, "/etc/default/login"); 1110 1111 if (tmpenv == NULL) 1112 return; 1113 1114 if (uid == 0) 1115 var = child_get_env(tmpenv, "SUPATH"); 1116 else 1117 var = child_get_env(tmpenv, "PATH"); 1118 if (var != NULL) 1119 child_set_env(env, envsize, "PATH", var); 1120 1121 if ((var = child_get_env(tmpenv, "UMASK")) != NULL) 1122 if (sscanf(var, "%5lo", &mask) == 1) 1123 umask((mode_t)mask); 1124 1125 for (i = 0; tmpenv[i] != NULL; i++) 1126 free(tmpenv[i]); 1127 free(tmpenv); 1128 } 1129 #endif /* HAVE_ETC_DEFAULT_LOGIN */ 1130 1131 void 1132 copy_environment(char **source, char ***env, u_int *envsize) 1133 { 1134 char *var_name, *var_val; 1135 int i; 1136 1137 if (source == NULL) 1138 return; 1139 1140 for(i = 0; source[i] != NULL; i++) { 1141 var_name = xstrdup(source[i]); 1142 if ((var_val = strstr(var_name, "=")) == NULL) { 1143 free(var_name); 1144 continue; 1145 } 1146 *var_val++ = '\0'; 1147 1148 debug3("Copy environment: %s=%s", var_name, var_val); 1149 child_set_env(env, envsize, var_name, var_val); 1150 1151 free(var_name); 1152 } 1153 } 1154 1155 static char ** 1156 do_setup_env(Session *s, const char *shell) 1157 { 1158 char buf[256]; 1159 u_int i, envsize; 1160 char **env, *laddr; 1161 struct passwd *pw = s->pw; 1162 #if !defined (HAVE_LOGIN_CAP) && !defined (HAVE_CYGWIN) 1163 char *path = NULL; 1164 #else 1165 extern char **environ; 1166 char **senv; 1167 #if 0 1168 char **var; 1169 #endif 1170 #endif 1171 1172 /* Initialize the environment. */ 1173 envsize = 100; 1174 env = xcalloc(envsize, sizeof(char *)); 1175 env[0] = NULL; 1176 1177 #ifdef HAVE_CYGWIN 1178 /* 1179 * The Windows environment contains some setting which are 1180 * important for a running system. They must not be dropped. 1181 */ 1182 { 1183 char **p; 1184 1185 p = fetch_windows_environment(); 1186 copy_environment(p, &env, &envsize); 1187 free_windows_environment(p); 1188 } 1189 #endif 1190 1191 if (getenv("TZ")) 1192 child_set_env(&env, &envsize, "TZ", getenv("TZ")); 1193 1194 #ifdef GSSAPI 1195 /* Allow any GSSAPI methods that we've used to alter 1196 * the childs environment as they see fit 1197 */ 1198 ssh_gssapi_do_child(&env, &envsize); 1199 #endif 1200 1201 if (!options.use_login) { 1202 /* Set basic environment. */ 1203 for (i = 0; i < s->num_env; i++) 1204 child_set_env(&env, &envsize, s->env[i].name, 1205 s->env[i].val); 1206 1207 child_set_env(&env, &envsize, "USER", pw->pw_name); 1208 child_set_env(&env, &envsize, "LOGNAME", pw->pw_name); 1209 #ifdef _AIX 1210 child_set_env(&env, &envsize, "LOGIN", pw->pw_name); 1211 #endif 1212 child_set_env(&env, &envsize, "HOME", pw->pw_dir); 1213 snprintf(buf, sizeof buf, "%.200s/%.50s", 1214 _PATH_MAILDIR, pw->pw_name); 1215 child_set_env(&env, &envsize, "MAIL", buf); 1216 #ifdef HAVE_LOGIN_CAP 1217 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); 1218 child_set_env(&env, &envsize, "TERM", "su"); 1219 senv = environ; 1220 environ = xmalloc(sizeof(char *)); 1221 *environ = NULL; 1222 (void) setusercontext(lc, pw, pw->pw_uid, 1223 LOGIN_SETENV|LOGIN_SETPATH); 1224 copy_environment(environ, &env, &envsize); 1225 #if 0 1226 /* 1227 * This interferes with libc's management of the environment 1228 * in horrible ways that can cause sshd to crash. 1229 */ 1230 for (var = environ; *var != NULL; ++var) 1231 xfree(*var); 1232 xfree(environ); 1233 #endif 1234 environ = senv; 1235 #else /* HAVE_LOGIN_CAP */ 1236 # ifndef HAVE_CYGWIN 1237 /* 1238 * There's no standard path on Windows. The path contains 1239 * important components pointing to the system directories, 1240 * needed for loading shared libraries. So the path better 1241 * remains intact here. 1242 */ 1243 # ifdef HAVE_ETC_DEFAULT_LOGIN 1244 read_etc_default_login(&env, &envsize, pw->pw_uid); 1245 path = child_get_env(env, "PATH"); 1246 # endif /* HAVE_ETC_DEFAULT_LOGIN */ 1247 if (path == NULL || *path == '\0') { 1248 child_set_env(&env, &envsize, "PATH", 1249 s->pw->pw_uid == 0 ? 1250 SUPERUSER_PATH : _PATH_STDPATH); 1251 } 1252 # endif /* HAVE_CYGWIN */ 1253 #endif /* HAVE_LOGIN_CAP */ 1254 1255 /* Normal systems set SHELL by default. */ 1256 child_set_env(&env, &envsize, "SHELL", shell); 1257 } 1258 1259 /* Set custom environment options from RSA authentication. */ 1260 if (!options.use_login) { 1261 while (custom_environment) { 1262 struct envstring *ce = custom_environment; 1263 char *str = ce->s; 1264 1265 for (i = 0; str[i] != '=' && str[i]; i++) 1266 ; 1267 if (str[i] == '=') { 1268 str[i] = 0; 1269 child_set_env(&env, &envsize, str, str + i + 1); 1270 } 1271 custom_environment = ce->next; 1272 free(ce->s); 1273 free(ce); 1274 } 1275 } 1276 1277 /* SSH_CLIENT deprecated */ 1278 snprintf(buf, sizeof buf, "%.50s %d %d", 1279 get_remote_ipaddr(), get_remote_port(), get_local_port()); 1280 child_set_env(&env, &envsize, "SSH_CLIENT", buf); 1281 1282 laddr = get_local_ipaddr(packet_get_connection_in()); 1283 snprintf(buf, sizeof buf, "%.50s %d %.50s %d", 1284 get_remote_ipaddr(), get_remote_port(), laddr, get_local_port()); 1285 free(laddr); 1286 child_set_env(&env, &envsize, "SSH_CONNECTION", buf); 1287 1288 if (s->ttyfd != -1) 1289 child_set_env(&env, &envsize, "SSH_TTY", s->tty); 1290 if (s->term) 1291 child_set_env(&env, &envsize, "TERM", s->term); 1292 if (s->display) 1293 child_set_env(&env, &envsize, "DISPLAY", s->display); 1294 if (original_command) 1295 child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND", 1296 original_command); 1297 1298 #ifdef _UNICOS 1299 if (cray_tmpdir[0] != '\0') 1300 child_set_env(&env, &envsize, "TMPDIR", cray_tmpdir); 1301 #endif /* _UNICOS */ 1302 1303 /* 1304 * Since we clear KRB5CCNAME at startup, if it's set now then it 1305 * must have been set by a native authentication method (eg AIX or 1306 * SIA), so copy it to the child. 1307 */ 1308 { 1309 char *cp; 1310 1311 if ((cp = getenv("KRB5CCNAME")) != NULL) 1312 child_set_env(&env, &envsize, "KRB5CCNAME", cp); 1313 } 1314 1315 #ifdef _AIX 1316 { 1317 char *cp; 1318 1319 if ((cp = getenv("AUTHSTATE")) != NULL) 1320 child_set_env(&env, &envsize, "AUTHSTATE", cp); 1321 read_environment_file(&env, &envsize, "/etc/environment"); 1322 } 1323 #endif 1324 #ifdef KRB5 1325 if (s->authctxt->krb5_ccname) 1326 child_set_env(&env, &envsize, "KRB5CCNAME", 1327 s->authctxt->krb5_ccname); 1328 #endif 1329 #ifdef USE_PAM 1330 /* 1331 * Pull in any environment variables that may have 1332 * been set by PAM. 1333 */ 1334 if (options.use_pam) { 1335 char **p; 1336 1337 p = fetch_pam_child_environment(); 1338 copy_environment(p, &env, &envsize); 1339 free_pam_environment(p); 1340 1341 p = fetch_pam_environment(); 1342 copy_environment(p, &env, &envsize); 1343 free_pam_environment(p); 1344 } 1345 #endif /* USE_PAM */ 1346 1347 if (auth_sock_name != NULL) 1348 child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME, 1349 auth_sock_name); 1350 1351 /* read $HOME/.ssh/environment. */ 1352 if (options.permit_user_env && !options.use_login) { 1353 snprintf(buf, sizeof buf, "%.200s/.ssh/environment", 1354 strcmp(pw->pw_dir, "/") ? pw->pw_dir : ""); 1355 read_environment_file(&env, &envsize, buf); 1356 } 1357 if (debug_flag) { 1358 /* dump the environment */ 1359 fprintf(stderr, "Environment:\n"); 1360 for (i = 0; env[i]; i++) 1361 fprintf(stderr, " %.200s\n", env[i]); 1362 } 1363 return env; 1364 } 1365 1366 /* 1367 * Run $HOME/.ssh/rc, /etc/ssh/sshrc, or xauth (whichever is found 1368 * first in this order). 1369 */ 1370 static void 1371 do_rc_files(Session *s, const char *shell) 1372 { 1373 FILE *f = NULL; 1374 char cmd[1024]; 1375 int do_xauth; 1376 struct stat st; 1377 1378 do_xauth = 1379 s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL; 1380 1381 /* ignore _PATH_SSH_USER_RC for subsystems and admin forced commands */ 1382 if (!s->is_subsystem && options.adm_forced_command == NULL && 1383 !no_user_rc && options.permit_user_rc && 1384 stat(_PATH_SSH_USER_RC, &st) >= 0) { 1385 snprintf(cmd, sizeof cmd, "%s -c '%s %s'", 1386 shell, _PATH_BSHELL, _PATH_SSH_USER_RC); 1387 if (debug_flag) 1388 fprintf(stderr, "Running %s\n", cmd); 1389 f = popen(cmd, "w"); 1390 if (f) { 1391 if (do_xauth) 1392 fprintf(f, "%s %s\n", s->auth_proto, 1393 s->auth_data); 1394 pclose(f); 1395 } else 1396 fprintf(stderr, "Could not run %s\n", 1397 _PATH_SSH_USER_RC); 1398 } else if (stat(_PATH_SSH_SYSTEM_RC, &st) >= 0) { 1399 if (debug_flag) 1400 fprintf(stderr, "Running %s %s\n", _PATH_BSHELL, 1401 _PATH_SSH_SYSTEM_RC); 1402 f = popen(_PATH_BSHELL " " _PATH_SSH_SYSTEM_RC, "w"); 1403 if (f) { 1404 if (do_xauth) 1405 fprintf(f, "%s %s\n", s->auth_proto, 1406 s->auth_data); 1407 pclose(f); 1408 } else 1409 fprintf(stderr, "Could not run %s\n", 1410 _PATH_SSH_SYSTEM_RC); 1411 } else if (do_xauth && options.xauth_location != NULL) { 1412 /* Add authority data to .Xauthority if appropriate. */ 1413 if (debug_flag) { 1414 fprintf(stderr, 1415 "Running %.500s remove %.100s\n", 1416 options.xauth_location, s->auth_display); 1417 fprintf(stderr, 1418 "%.500s add %.100s %.100s %.100s\n", 1419 options.xauth_location, s->auth_display, 1420 s->auth_proto, s->auth_data); 1421 } 1422 snprintf(cmd, sizeof cmd, "%s -q -", 1423 options.xauth_location); 1424 f = popen(cmd, "w"); 1425 if (f) { 1426 fprintf(f, "remove %s\n", 1427 s->auth_display); 1428 fprintf(f, "add %s %s %s\n", 1429 s->auth_display, s->auth_proto, 1430 s->auth_data); 1431 pclose(f); 1432 } else { 1433 fprintf(stderr, "Could not run %s\n", 1434 cmd); 1435 } 1436 } 1437 } 1438 1439 static void 1440 do_nologin(struct passwd *pw) 1441 { 1442 FILE *f = NULL; 1443 char buf[1024], *nl, *def_nl = _PATH_NOLOGIN; 1444 struct stat sb; 1445 1446 #ifdef HAVE_LOGIN_CAP 1447 if (login_getcapbool(lc, "ignorenologin", 0) || pw->pw_uid == 0) 1448 return; 1449 nl = login_getcapstr(lc, "nologin", def_nl, def_nl); 1450 #else 1451 if (pw->pw_uid == 0) 1452 return; 1453 nl = def_nl; 1454 #endif 1455 if (stat(nl, &sb) == -1) { 1456 if (nl != def_nl) 1457 free(nl); 1458 return; 1459 } 1460 1461 /* /etc/nologin exists. Print its contents if we can and exit. */ 1462 logit("User %.100s not allowed because %s exists", pw->pw_name, nl); 1463 if ((f = fopen(nl, "r")) != NULL) { 1464 while (fgets(buf, sizeof(buf), f)) 1465 fputs(buf, stderr); 1466 fclose(f); 1467 } 1468 exit(254); 1469 } 1470 1471 /* 1472 * Chroot into a directory after checking it for safety: all path components 1473 * must be root-owned directories with strict permissions. 1474 */ 1475 static void 1476 safely_chroot(const char *path, uid_t uid) 1477 { 1478 const char *cp; 1479 char component[MAXPATHLEN]; 1480 struct stat st; 1481 1482 if (*path != '/') 1483 fatal("chroot path does not begin at root"); 1484 if (strlen(path) >= sizeof(component)) 1485 fatal("chroot path too long"); 1486 1487 /* 1488 * Descend the path, checking that each component is a 1489 * root-owned directory with strict permissions. 1490 */ 1491 for (cp = path; cp != NULL;) { 1492 if ((cp = strchr(cp, '/')) == NULL) 1493 strlcpy(component, path, sizeof(component)); 1494 else { 1495 cp++; 1496 memcpy(component, path, cp - path); 1497 component[cp - path] = '\0'; 1498 } 1499 1500 debug3("%s: checking '%s'", __func__, component); 1501 1502 if (stat(component, &st) != 0) 1503 fatal("%s: stat(\"%s\"): %s", __func__, 1504 component, strerror(errno)); 1505 if (st.st_uid != 0 || (st.st_mode & 022) != 0) 1506 fatal("bad ownership or modes for chroot " 1507 "directory %s\"%s\"", 1508 cp == NULL ? "" : "component ", component); 1509 if (!S_ISDIR(st.st_mode)) 1510 fatal("chroot path %s\"%s\" is not a directory", 1511 cp == NULL ? "" : "component ", component); 1512 1513 } 1514 1515 if (chdir(path) == -1) 1516 fatal("Unable to chdir to chroot path \"%s\": " 1517 "%s", path, strerror(errno)); 1518 if (chroot(path) == -1) 1519 fatal("chroot(\"%s\"): %s", path, strerror(errno)); 1520 if (chdir("/") == -1) 1521 fatal("%s: chdir(/) after chroot: %s", 1522 __func__, strerror(errno)); 1523 verbose("Changed root directory to \"%s\"", path); 1524 } 1525 1526 /* Set login name, uid, gid, and groups. */ 1527 void 1528 do_setusercontext(struct passwd *pw) 1529 { 1530 char *chroot_path, *tmp; 1531 #ifdef USE_LIBIAF 1532 int doing_chroot = 0; 1533 #endif 1534 1535 platform_setusercontext(pw); 1536 1537 if (platform_privileged_uidswap()) { 1538 #ifdef HAVE_LOGIN_CAP 1539 if (setusercontext(lc, pw, pw->pw_uid, 1540 (LOGIN_SETALL & ~(LOGIN_SETPATH|LOGIN_SETUSER))) < 0) { 1541 perror("unable to set user context"); 1542 exit(1); 1543 } 1544 #else 1545 if (setlogin(pw->pw_name) < 0) 1546 error("setlogin failed: %s", strerror(errno)); 1547 if (setgid(pw->pw_gid) < 0) { 1548 perror("setgid"); 1549 exit(1); 1550 } 1551 /* Initialize the group list. */ 1552 if (initgroups(pw->pw_name, pw->pw_gid) < 0) { 1553 perror("initgroups"); 1554 exit(1); 1555 } 1556 endgrent(); 1557 #endif 1558 1559 platform_setusercontext_post_groups(pw); 1560 1561 if (options.chroot_directory != NULL && 1562 strcasecmp(options.chroot_directory, "none") != 0) { 1563 tmp = tilde_expand_filename(options.chroot_directory, 1564 pw->pw_uid); 1565 chroot_path = percent_expand(tmp, "h", pw->pw_dir, 1566 "u", pw->pw_name, (char *)NULL); 1567 safely_chroot(chroot_path, pw->pw_uid); 1568 free(tmp); 1569 free(chroot_path); 1570 /* Make sure we don't attempt to chroot again */ 1571 free(options.chroot_directory); 1572 options.chroot_directory = NULL; 1573 #ifdef USE_LIBIAF 1574 doing_chroot = 1; 1575 #endif 1576 } 1577 1578 #ifdef HAVE_LOGIN_CAP 1579 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUSER) < 0) { 1580 perror("unable to set user context (setuser)"); 1581 exit(1); 1582 } 1583 /* 1584 * FreeBSD's setusercontext() will not apply the user's 1585 * own umask setting unless running with the user's UID. 1586 */ 1587 (void) setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUMASK); 1588 #else 1589 # ifdef USE_LIBIAF 1590 /* In a chroot environment, the set_id() will always fail; typically 1591 * because of the lack of necessary authentication services and runtime 1592 * such as ./usr/lib/libiaf.so, ./usr/lib/libpam.so.1, and ./etc/passwd 1593 * We skip it in the internal sftp chroot case. 1594 * We'll lose auditing and ACLs but permanently_set_uid will 1595 * take care of the rest. 1596 */ 1597 if ((doing_chroot == 0) && set_id(pw->pw_name) != 0) { 1598 fatal("set_id(%s) Failed", pw->pw_name); 1599 } 1600 # endif /* USE_LIBIAF */ 1601 /* Permanently switch to the desired uid. */ 1602 permanently_set_uid(pw); 1603 #endif 1604 } else if (options.chroot_directory != NULL && 1605 strcasecmp(options.chroot_directory, "none") != 0) { 1606 fatal("server lacks privileges to chroot to ChrootDirectory"); 1607 } 1608 1609 if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) 1610 fatal("Failed to set uids to %u.", (u_int) pw->pw_uid); 1611 } 1612 1613 static void 1614 do_pwchange(Session *s) 1615 { 1616 fflush(NULL); 1617 fprintf(stderr, "WARNING: Your password has expired.\n"); 1618 if (s->ttyfd != -1) { 1619 fprintf(stderr, 1620 "You must change your password now and login again!\n"); 1621 #ifdef WITH_SELINUX 1622 setexeccon(NULL); 1623 #endif 1624 #ifdef PASSWD_NEEDS_USERNAME 1625 execl(_PATH_PASSWD_PROG, "passwd", s->pw->pw_name, 1626 (char *)NULL); 1627 #else 1628 execl(_PATH_PASSWD_PROG, "passwd", (char *)NULL); 1629 #endif 1630 perror("passwd"); 1631 } else { 1632 fprintf(stderr, 1633 "Password change required but no TTY available.\n"); 1634 } 1635 exit(1); 1636 } 1637 1638 static void 1639 launch_login(struct passwd *pw, const char *hostname) 1640 { 1641 /* Launch login(1). */ 1642 1643 execl(LOGIN_PROGRAM, "login", "-h", hostname, 1644 #ifdef xxxLOGIN_NEEDS_TERM 1645 (s->term ? s->term : "unknown"), 1646 #endif /* LOGIN_NEEDS_TERM */ 1647 #ifdef LOGIN_NO_ENDOPT 1648 "-p", "-f", pw->pw_name, (char *)NULL); 1649 #else 1650 "-p", "-f", "--", pw->pw_name, (char *)NULL); 1651 #endif 1652 1653 /* Login couldn't be executed, die. */ 1654 1655 perror("login"); 1656 exit(1); 1657 } 1658 1659 static void 1660 child_close_fds(void) 1661 { 1662 extern AuthenticationConnection *auth_conn; 1663 1664 if (auth_conn) { 1665 ssh_close_authentication_connection(auth_conn); 1666 auth_conn = NULL; 1667 } 1668 1669 if (packet_get_connection_in() == packet_get_connection_out()) 1670 close(packet_get_connection_in()); 1671 else { 1672 close(packet_get_connection_in()); 1673 close(packet_get_connection_out()); 1674 } 1675 /* 1676 * Close all descriptors related to channels. They will still remain 1677 * open in the parent. 1678 */ 1679 /* XXX better use close-on-exec? -markus */ 1680 channel_close_all(); 1681 1682 /* 1683 * Close any extra file descriptors. Note that there may still be 1684 * descriptors left by system functions. They will be closed later. 1685 */ 1686 endpwent(); 1687 1688 /* 1689 * Close any extra open file descriptors so that we don't have them 1690 * hanging around in clients. Note that we want to do this after 1691 * initgroups, because at least on Solaris 2.3 it leaves file 1692 * descriptors open. 1693 */ 1694 closefrom(STDERR_FILENO + 1); 1695 } 1696 1697 /* 1698 * Performs common processing for the child, such as setting up the 1699 * environment, closing extra file descriptors, setting the user and group 1700 * ids, and executing the command or shell. 1701 */ 1702 #define ARGV_MAX 10 1703 void 1704 do_child(Session *s, const char *command) 1705 { 1706 extern char **environ; 1707 char **env; 1708 char *argv[ARGV_MAX]; 1709 const char *shell, *shell0, *hostname = NULL; 1710 struct passwd *pw = s->pw; 1711 int r = 0; 1712 1713 /* remove hostkey from the child's memory */ 1714 destroy_sensitive_data(); 1715 1716 /* Force a password change */ 1717 if (s->authctxt->force_pwchange) { 1718 do_setusercontext(pw); 1719 child_close_fds(); 1720 do_pwchange(s); 1721 exit(1); 1722 } 1723 1724 /* login(1) is only called if we execute the login shell */ 1725 if (options.use_login && command != NULL) 1726 options.use_login = 0; 1727 1728 #ifdef _UNICOS 1729 cray_setup(pw->pw_uid, pw->pw_name, command); 1730 #endif /* _UNICOS */ 1731 1732 /* 1733 * Login(1) does this as well, and it needs uid 0 for the "-h" 1734 * switch, so we let login(1) to this for us. 1735 */ 1736 if (!options.use_login) { 1737 #ifdef HAVE_OSF_SIA 1738 session_setup_sia(pw, s->ttyfd == -1 ? NULL : s->tty); 1739 if (!check_quietlogin(s, command)) 1740 do_motd(); 1741 #else /* HAVE_OSF_SIA */ 1742 /* When PAM is enabled we rely on it to do the nologin check */ 1743 if (!options.use_pam) 1744 do_nologin(pw); 1745 do_setusercontext(pw); 1746 /* 1747 * PAM session modules in do_setusercontext may have 1748 * generated messages, so if this in an interactive 1749 * login then display them too. 1750 */ 1751 if (!check_quietlogin(s, command)) 1752 display_loginmsg(); 1753 #endif /* HAVE_OSF_SIA */ 1754 } 1755 1756 #ifdef USE_PAM 1757 if (options.use_pam && !options.use_login && !is_pam_session_open()) { 1758 debug3("PAM session not opened, exiting"); 1759 display_loginmsg(); 1760 exit(254); 1761 } 1762 #endif 1763 1764 /* 1765 * Get the shell from the password data. An empty shell field is 1766 * legal, and means /bin/sh. 1767 */ 1768 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; 1769 1770 /* 1771 * Make sure $SHELL points to the shell from the password file, 1772 * even if shell is overridden from login.conf 1773 */ 1774 env = do_setup_env(s, shell); 1775 1776 #ifdef HAVE_LOGIN_CAP 1777 shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell); 1778 #endif 1779 1780 /* we have to stash the hostname before we close our socket. */ 1781 if (options.use_login) 1782 hostname = get_remote_name_or_ip(utmp_len, 1783 options.use_dns); 1784 /* 1785 * Close the connection descriptors; note that this is the child, and 1786 * the server will still have the socket open, and it is important 1787 * that we do not shutdown it. Note that the descriptors cannot be 1788 * closed before building the environment, as we call 1789 * get_remote_ipaddr there. 1790 */ 1791 child_close_fds(); 1792 1793 /* 1794 * Must take new environment into use so that .ssh/rc, 1795 * /etc/ssh/sshrc and xauth are run in the proper environment. 1796 */ 1797 environ = env; 1798 1799 #if defined(KRB5) && defined(USE_AFS) 1800 /* 1801 * At this point, we check to see if AFS is active and if we have 1802 * a valid Kerberos 5 TGT. If so, it seems like a good idea to see 1803 * if we can (and need to) extend the ticket into an AFS token. If 1804 * we don't do this, we run into potential problems if the user's 1805 * home directory is in AFS and it's not world-readable. 1806 */ 1807 1808 if (options.kerberos_get_afs_token && k_hasafs() && 1809 (s->authctxt->krb5_ctx != NULL)) { 1810 char cell[64]; 1811 1812 debug("Getting AFS token"); 1813 1814 k_setpag(); 1815 1816 if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0) 1817 krb5_afslog(s->authctxt->krb5_ctx, 1818 s->authctxt->krb5_fwd_ccache, cell, NULL); 1819 1820 krb5_afslog_home(s->authctxt->krb5_ctx, 1821 s->authctxt->krb5_fwd_ccache, NULL, NULL, pw->pw_dir); 1822 } 1823 #endif 1824 1825 /* Change current directory to the user's home directory. */ 1826 if (chdir(pw->pw_dir) < 0) { 1827 /* Suppress missing homedir warning for chroot case */ 1828 #ifdef HAVE_LOGIN_CAP 1829 r = login_getcapbool(lc, "requirehome", 0); 1830 #endif 1831 if (r || options.chroot_directory == NULL || 1832 strcasecmp(options.chroot_directory, "none") == 0) 1833 fprintf(stderr, "Could not chdir to home " 1834 "directory %s: %s\n", pw->pw_dir, 1835 strerror(errno)); 1836 if (r) 1837 exit(1); 1838 } 1839 1840 closefrom(STDERR_FILENO + 1); 1841 1842 if (!options.use_login) 1843 do_rc_files(s, shell); 1844 1845 /* restore SIGPIPE for child */ 1846 signal(SIGPIPE, SIG_DFL); 1847 1848 if (s->is_subsystem == SUBSYSTEM_INT_SFTP_ERROR) { 1849 printf("This service allows sftp connections only.\n"); 1850 fflush(NULL); 1851 exit(1); 1852 } else if (s->is_subsystem == SUBSYSTEM_INT_SFTP) { 1853 extern int optind, optreset; 1854 int i; 1855 char *p, *args; 1856 1857 setproctitle("%s@%s", s->pw->pw_name, INTERNAL_SFTP_NAME); 1858 args = xstrdup(command ? command : "sftp-server"); 1859 for (i = 0, (p = strtok(args, " ")); p; (p = strtok(NULL, " "))) 1860 if (i < ARGV_MAX - 1) 1861 argv[i++] = p; 1862 argv[i] = NULL; 1863 optind = optreset = 1; 1864 __progname = argv[0]; 1865 #ifdef WITH_SELINUX 1866 ssh_selinux_change_context("sftpd_t"); 1867 #endif 1868 exit(sftp_server_main(i, argv, s->pw)); 1869 } 1870 1871 fflush(NULL); 1872 1873 if (options.use_login) { 1874 launch_login(pw, hostname); 1875 /* NEVERREACHED */ 1876 } 1877 1878 /* Get the last component of the shell name. */ 1879 if ((shell0 = strrchr(shell, '/')) != NULL) 1880 shell0++; 1881 else 1882 shell0 = shell; 1883 1884 /* 1885 * If we have no command, execute the shell. In this case, the shell 1886 * name to be passed in argv[0] is preceded by '-' to indicate that 1887 * this is a login shell. 1888 */ 1889 if (!command) { 1890 char argv0[256]; 1891 1892 /* Start the shell. Set initial character to '-'. */ 1893 argv0[0] = '-'; 1894 1895 if (strlcpy(argv0 + 1, shell0, sizeof(argv0) - 1) 1896 >= sizeof(argv0) - 1) { 1897 errno = EINVAL; 1898 perror(shell); 1899 exit(1); 1900 } 1901 1902 /* Execute the shell. */ 1903 argv[0] = argv0; 1904 argv[1] = NULL; 1905 execve(shell, argv, env); 1906 1907 /* Executing the shell failed. */ 1908 perror(shell); 1909 exit(1); 1910 } 1911 /* 1912 * Execute the command using the user's shell. This uses the -c 1913 * option to execute the command. 1914 */ 1915 argv[0] = (char *) shell0; 1916 argv[1] = "-c"; 1917 argv[2] = (char *) command; 1918 argv[3] = NULL; 1919 execve(shell, argv, env); 1920 perror(shell); 1921 exit(1); 1922 } 1923 1924 void 1925 session_unused(int id) 1926 { 1927 debug3("%s: session id %d unused", __func__, id); 1928 if (id >= options.max_sessions || 1929 id >= sessions_nalloc) { 1930 fatal("%s: insane session id %d (max %d nalloc %d)", 1931 __func__, id, options.max_sessions, sessions_nalloc); 1932 } 1933 memset(&sessions[id], 0, sizeof(*sessions)); 1934 sessions[id].self = id; 1935 sessions[id].used = 0; 1936 sessions[id].chanid = -1; 1937 sessions[id].ptyfd = -1; 1938 sessions[id].ttyfd = -1; 1939 sessions[id].ptymaster = -1; 1940 sessions[id].x11_chanids = NULL; 1941 sessions[id].next_unused = sessions_first_unused; 1942 sessions_first_unused = id; 1943 } 1944 1945 Session * 1946 session_new(void) 1947 { 1948 Session *s, *tmp; 1949 1950 if (sessions_first_unused == -1) { 1951 if (sessions_nalloc >= options.max_sessions) 1952 return NULL; 1953 debug2("%s: allocate (allocated %d max %d)", 1954 __func__, sessions_nalloc, options.max_sessions); 1955 tmp = xrealloc(sessions, sessions_nalloc + 1, 1956 sizeof(*sessions)); 1957 if (tmp == NULL) { 1958 error("%s: cannot allocate %d sessions", 1959 __func__, sessions_nalloc + 1); 1960 return NULL; 1961 } 1962 sessions = tmp; 1963 session_unused(sessions_nalloc++); 1964 } 1965 1966 if (sessions_first_unused >= sessions_nalloc || 1967 sessions_first_unused < 0) { 1968 fatal("%s: insane first_unused %d max %d nalloc %d", 1969 __func__, sessions_first_unused, options.max_sessions, 1970 sessions_nalloc); 1971 } 1972 1973 s = &sessions[sessions_first_unused]; 1974 if (s->used) { 1975 fatal("%s: session %d already used", 1976 __func__, sessions_first_unused); 1977 } 1978 sessions_first_unused = s->next_unused; 1979 s->used = 1; 1980 s->next_unused = -1; 1981 debug("session_new: session %d", s->self); 1982 1983 return s; 1984 } 1985 1986 static void 1987 session_dump(void) 1988 { 1989 int i; 1990 for (i = 0; i < sessions_nalloc; i++) { 1991 Session *s = &sessions[i]; 1992 1993 debug("dump: used %d next_unused %d session %d %p " 1994 "channel %d pid %ld", 1995 s->used, 1996 s->next_unused, 1997 s->self, 1998 s, 1999 s->chanid, 2000 (long)s->pid); 2001 } 2002 } 2003 2004 int 2005 session_open(Authctxt *authctxt, int chanid) 2006 { 2007 Session *s = session_new(); 2008 debug("session_open: channel %d", chanid); 2009 if (s == NULL) { 2010 error("no more sessions"); 2011 return 0; 2012 } 2013 s->authctxt = authctxt; 2014 s->pw = authctxt->pw; 2015 if (s->pw == NULL || !authctxt->valid) 2016 fatal("no user for session %d", s->self); 2017 debug("session_open: session %d: link with channel %d", s->self, chanid); 2018 s->chanid = chanid; 2019 return 1; 2020 } 2021 2022 Session * 2023 session_by_tty(char *tty) 2024 { 2025 int i; 2026 for (i = 0; i < sessions_nalloc; i++) { 2027 Session *s = &sessions[i]; 2028 if (s->used && s->ttyfd != -1 && strcmp(s->tty, tty) == 0) { 2029 debug("session_by_tty: session %d tty %s", i, tty); 2030 return s; 2031 } 2032 } 2033 debug("session_by_tty: unknown tty %.100s", tty); 2034 session_dump(); 2035 return NULL; 2036 } 2037 2038 static Session * 2039 session_by_channel(int id) 2040 { 2041 int i; 2042 for (i = 0; i < sessions_nalloc; i++) { 2043 Session *s = &sessions[i]; 2044 if (s->used && s->chanid == id) { 2045 debug("session_by_channel: session %d channel %d", 2046 i, id); 2047 return s; 2048 } 2049 } 2050 debug("session_by_channel: unknown channel %d", id); 2051 session_dump(); 2052 return NULL; 2053 } 2054 2055 static Session * 2056 session_by_x11_channel(int id) 2057 { 2058 int i, j; 2059 2060 for (i = 0; i < sessions_nalloc; i++) { 2061 Session *s = &sessions[i]; 2062 2063 if (s->x11_chanids == NULL || !s->used) 2064 continue; 2065 for (j = 0; s->x11_chanids[j] != -1; j++) { 2066 if (s->x11_chanids[j] == id) { 2067 debug("session_by_x11_channel: session %d " 2068 "channel %d", s->self, id); 2069 return s; 2070 } 2071 } 2072 } 2073 debug("session_by_x11_channel: unknown channel %d", id); 2074 session_dump(); 2075 return NULL; 2076 } 2077 2078 static Session * 2079 session_by_pid(pid_t pid) 2080 { 2081 int i; 2082 debug("session_by_pid: pid %ld", (long)pid); 2083 for (i = 0; i < sessions_nalloc; i++) { 2084 Session *s = &sessions[i]; 2085 if (s->used && s->pid == pid) 2086 return s; 2087 } 2088 error("session_by_pid: unknown pid %ld", (long)pid); 2089 session_dump(); 2090 return NULL; 2091 } 2092 2093 static int 2094 session_window_change_req(Session *s) 2095 { 2096 s->col = packet_get_int(); 2097 s->row = packet_get_int(); 2098 s->xpixel = packet_get_int(); 2099 s->ypixel = packet_get_int(); 2100 packet_check_eom(); 2101 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 2102 return 1; 2103 } 2104 2105 static int 2106 session_pty_req(Session *s) 2107 { 2108 u_int len; 2109 int n_bytes; 2110 2111 if (no_pty_flag || !options.permit_tty) { 2112 debug("Allocating a pty not permitted for this authentication."); 2113 return 0; 2114 } 2115 if (s->ttyfd != -1) { 2116 packet_disconnect("Protocol error: you already have a pty."); 2117 return 0; 2118 } 2119 2120 s->term = packet_get_string(&len); 2121 2122 if (compat20) { 2123 s->col = packet_get_int(); 2124 s->row = packet_get_int(); 2125 } else { 2126 s->row = packet_get_int(); 2127 s->col = packet_get_int(); 2128 } 2129 s->xpixel = packet_get_int(); 2130 s->ypixel = packet_get_int(); 2131 2132 if (strcmp(s->term, "") == 0) { 2133 free(s->term); 2134 s->term = NULL; 2135 } 2136 2137 /* Allocate a pty and open it. */ 2138 debug("Allocating pty."); 2139 if (!PRIVSEP(pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, 2140 sizeof(s->tty)))) { 2141 free(s->term); 2142 s->term = NULL; 2143 s->ptyfd = -1; 2144 s->ttyfd = -1; 2145 error("session_pty_req: session %d alloc failed", s->self); 2146 return 0; 2147 } 2148 debug("session_pty_req: session %d alloc %s", s->self, s->tty); 2149 2150 /* for SSH1 the tty modes length is not given */ 2151 if (!compat20) 2152 n_bytes = packet_remaining(); 2153 tty_parse_modes(s->ttyfd, &n_bytes); 2154 2155 if (!use_privsep) 2156 pty_setowner(s->pw, s->tty); 2157 2158 /* Set window size from the packet. */ 2159 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 2160 2161 packet_check_eom(); 2162 session_proctitle(s); 2163 return 1; 2164 } 2165 2166 static int 2167 session_subsystem_req(Session *s) 2168 { 2169 struct stat st; 2170 u_int len; 2171 int success = 0; 2172 char *prog, *cmd; 2173 u_int i; 2174 2175 s->subsys = packet_get_string(&len); 2176 packet_check_eom(); 2177 debug2("subsystem request for %.100s by user %s", s->subsys, 2178 s->pw->pw_name); 2179 2180 for (i = 0; i < options.num_subsystems; i++) { 2181 if (strcmp(s->subsys, options.subsystem_name[i]) == 0) { 2182 prog = options.subsystem_command[i]; 2183 cmd = options.subsystem_args[i]; 2184 if (strcmp(INTERNAL_SFTP_NAME, prog) == 0) { 2185 s->is_subsystem = SUBSYSTEM_INT_SFTP; 2186 debug("subsystem: %s", prog); 2187 } else { 2188 if (stat(prog, &st) < 0) 2189 debug("subsystem: cannot stat %s: %s", 2190 prog, strerror(errno)); 2191 s->is_subsystem = SUBSYSTEM_EXT; 2192 debug("subsystem: exec() %s", cmd); 2193 } 2194 success = do_exec(s, cmd) == 0; 2195 break; 2196 } 2197 } 2198 2199 if (!success) 2200 logit("subsystem request for %.100s by user %s failed, " 2201 "subsystem not found", s->subsys, s->pw->pw_name); 2202 2203 return success; 2204 } 2205 2206 static int 2207 session_x11_req(Session *s) 2208 { 2209 int success; 2210 2211 if (s->auth_proto != NULL || s->auth_data != NULL) { 2212 error("session_x11_req: session %d: " 2213 "x11 forwarding already active", s->self); 2214 return 0; 2215 } 2216 s->single_connection = packet_get_char(); 2217 s->auth_proto = packet_get_string(NULL); 2218 s->auth_data = packet_get_string(NULL); 2219 s->screen = packet_get_int(); 2220 packet_check_eom(); 2221 2222 success = session_setup_x11fwd(s); 2223 if (!success) { 2224 free(s->auth_proto); 2225 free(s->auth_data); 2226 s->auth_proto = NULL; 2227 s->auth_data = NULL; 2228 } 2229 return success; 2230 } 2231 2232 static int 2233 session_shell_req(Session *s) 2234 { 2235 packet_check_eom(); 2236 return do_exec(s, NULL) == 0; 2237 } 2238 2239 static int 2240 session_exec_req(Session *s) 2241 { 2242 u_int len, success; 2243 2244 char *command = packet_get_string(&len); 2245 packet_check_eom(); 2246 success = do_exec(s, command) == 0; 2247 free(command); 2248 return success; 2249 } 2250 2251 static int 2252 session_break_req(Session *s) 2253 { 2254 2255 packet_get_int(); /* ignored */ 2256 packet_check_eom(); 2257 2258 if (s->ptymaster == -1 || tcsendbreak(s->ptymaster, 0) < 0) 2259 return 0; 2260 return 1; 2261 } 2262 2263 static int 2264 session_env_req(Session *s) 2265 { 2266 char *name, *val; 2267 u_int name_len, val_len, i; 2268 2269 name = packet_get_cstring(&name_len); 2270 val = packet_get_cstring(&val_len); 2271 packet_check_eom(); 2272 2273 /* Don't set too many environment variables */ 2274 if (s->num_env > 128) { 2275 debug2("Ignoring env request %s: too many env vars", name); 2276 goto fail; 2277 } 2278 2279 for (i = 0; i < options.num_accept_env; i++) { 2280 if (match_pattern(name, options.accept_env[i])) { 2281 debug2("Setting env %d: %s=%s", s->num_env, name, val); 2282 s->env = xrealloc(s->env, s->num_env + 1, 2283 sizeof(*s->env)); 2284 s->env[s->num_env].name = name; 2285 s->env[s->num_env].val = val; 2286 s->num_env++; 2287 return (1); 2288 } 2289 } 2290 debug2("Ignoring env request %s: disallowed name", name); 2291 2292 fail: 2293 free(name); 2294 free(val); 2295 return (0); 2296 } 2297 2298 static int 2299 session_auth_agent_req(Session *s) 2300 { 2301 static int called = 0; 2302 packet_check_eom(); 2303 if (no_agent_forwarding_flag || !options.allow_agent_forwarding) { 2304 debug("session_auth_agent_req: no_agent_forwarding_flag"); 2305 return 0; 2306 } 2307 if (called) { 2308 return 0; 2309 } else { 2310 called = 1; 2311 return auth_input_request_forwarding(s->pw); 2312 } 2313 } 2314 2315 int 2316 session_input_channel_req(Channel *c, const char *rtype) 2317 { 2318 int success = 0; 2319 Session *s; 2320 2321 if ((s = session_by_channel(c->self)) == NULL) { 2322 logit("session_input_channel_req: no session %d req %.100s", 2323 c->self, rtype); 2324 return 0; 2325 } 2326 debug("session_input_channel_req: session %d req %s", s->self, rtype); 2327 2328 /* 2329 * a session is in LARVAL state until a shell, a command 2330 * or a subsystem is executed 2331 */ 2332 if (c->type == SSH_CHANNEL_LARVAL) { 2333 if (strcmp(rtype, "shell") == 0) { 2334 success = session_shell_req(s); 2335 } else if (strcmp(rtype, "exec") == 0) { 2336 success = session_exec_req(s); 2337 } else if (strcmp(rtype, "pty-req") == 0) { 2338 success = session_pty_req(s); 2339 } else if (strcmp(rtype, "x11-req") == 0) { 2340 success = session_x11_req(s); 2341 } else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) { 2342 success = session_auth_agent_req(s); 2343 } else if (strcmp(rtype, "subsystem") == 0) { 2344 success = session_subsystem_req(s); 2345 } else if (strcmp(rtype, "env") == 0) { 2346 success = session_env_req(s); 2347 } 2348 } 2349 if (strcmp(rtype, "window-change") == 0) { 2350 success = session_window_change_req(s); 2351 } else if (strcmp(rtype, "break") == 0) { 2352 success = session_break_req(s); 2353 } 2354 2355 return success; 2356 } 2357 2358 void 2359 session_set_fds(Session *s, int fdin, int fdout, int fderr, int ignore_fderr, 2360 int is_tty) 2361 { 2362 if (!compat20) 2363 fatal("session_set_fds: called for proto != 2.0"); 2364 /* 2365 * now that have a child and a pipe to the child, 2366 * we can activate our channel and register the fd's 2367 */ 2368 if (s->chanid == -1) 2369 fatal("no channel for session %d", s->self); 2370 if (options.hpn_disabled) 2371 channel_set_fds(s->chanid, 2372 fdout, fdin, fderr, 2373 ignore_fderr ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ, 2374 1, is_tty, CHAN_SES_WINDOW_DEFAULT); 2375 else 2376 channel_set_fds(s->chanid, 2377 fdout, fdin, fderr, 2378 ignore_fderr ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ, 2379 1, is_tty, options.hpn_buffer_size); 2380 } 2381 2382 /* 2383 * Function to perform pty cleanup. Also called if we get aborted abnormally 2384 * (e.g., due to a dropped connection). 2385 */ 2386 void 2387 session_pty_cleanup2(Session *s) 2388 { 2389 if (s == NULL) { 2390 error("session_pty_cleanup: no session"); 2391 return; 2392 } 2393 if (s->ttyfd == -1) 2394 return; 2395 2396 debug("session_pty_cleanup: session %d release %s", s->self, s->tty); 2397 2398 /* Record that the user has logged out. */ 2399 if (s->pid != 0) 2400 record_logout(s->pid, s->tty, s->pw->pw_name); 2401 2402 /* Release the pseudo-tty. */ 2403 if (getuid() == 0) 2404 pty_release(s->tty); 2405 2406 /* 2407 * Close the server side of the socket pairs. We must do this after 2408 * the pty cleanup, so that another process doesn't get this pty 2409 * while we're still cleaning up. 2410 */ 2411 if (s->ptymaster != -1 && close(s->ptymaster) < 0) 2412 error("close(s->ptymaster/%d): %s", 2413 s->ptymaster, strerror(errno)); 2414 2415 /* unlink pty from session */ 2416 s->ttyfd = -1; 2417 } 2418 2419 void 2420 session_pty_cleanup(Session *s) 2421 { 2422 PRIVSEP(session_pty_cleanup2(s)); 2423 } 2424 2425 static char * 2426 sig2name(int sig) 2427 { 2428 #define SSH_SIG(x) if (sig == SIG ## x) return #x 2429 SSH_SIG(ABRT); 2430 SSH_SIG(ALRM); 2431 SSH_SIG(FPE); 2432 SSH_SIG(HUP); 2433 SSH_SIG(ILL); 2434 SSH_SIG(INT); 2435 SSH_SIG(KILL); 2436 SSH_SIG(PIPE); 2437 SSH_SIG(QUIT); 2438 SSH_SIG(SEGV); 2439 SSH_SIG(TERM); 2440 SSH_SIG(USR1); 2441 SSH_SIG(USR2); 2442 #undef SSH_SIG 2443 return "SIG@openssh.com"; 2444 } 2445 2446 static void 2447 session_close_x11(int id) 2448 { 2449 Channel *c; 2450 2451 if ((c = channel_by_id(id)) == NULL) { 2452 debug("session_close_x11: x11 channel %d missing", id); 2453 } else { 2454 /* Detach X11 listener */ 2455 debug("session_close_x11: detach x11 channel %d", id); 2456 channel_cancel_cleanup(id); 2457 if (c->ostate != CHAN_OUTPUT_CLOSED) 2458 chan_mark_dead(c); 2459 } 2460 } 2461 2462 static void 2463 session_close_single_x11(int id, void *arg) 2464 { 2465 Session *s; 2466 u_int i; 2467 2468 debug3("session_close_single_x11: channel %d", id); 2469 channel_cancel_cleanup(id); 2470 if ((s = session_by_x11_channel(id)) == NULL) 2471 fatal("session_close_single_x11: no x11 channel %d", id); 2472 for (i = 0; s->x11_chanids[i] != -1; i++) { 2473 debug("session_close_single_x11: session %d: " 2474 "closing channel %d", s->self, s->x11_chanids[i]); 2475 /* 2476 * The channel "id" is already closing, but make sure we 2477 * close all of its siblings. 2478 */ 2479 if (s->x11_chanids[i] != id) 2480 session_close_x11(s->x11_chanids[i]); 2481 } 2482 free(s->x11_chanids); 2483 s->x11_chanids = NULL; 2484 free(s->display); 2485 s->display = NULL; 2486 free(s->auth_proto); 2487 s->auth_proto = NULL; 2488 free(s->auth_data); 2489 s->auth_data = NULL; 2490 free(s->auth_display); 2491 s->auth_display = NULL; 2492 } 2493 2494 static void 2495 session_exit_message(Session *s, int status) 2496 { 2497 Channel *c; 2498 2499 if ((c = channel_lookup(s->chanid)) == NULL) 2500 fatal("session_exit_message: session %d: no channel %d", 2501 s->self, s->chanid); 2502 debug("session_exit_message: session %d channel %d pid %ld", 2503 s->self, s->chanid, (long)s->pid); 2504 2505 if (WIFEXITED(status)) { 2506 channel_request_start(s->chanid, "exit-status", 0); 2507 packet_put_int(WEXITSTATUS(status)); 2508 packet_send(); 2509 } else if (WIFSIGNALED(status)) { 2510 channel_request_start(s->chanid, "exit-signal", 0); 2511 packet_put_cstring(sig2name(WTERMSIG(status))); 2512 #ifdef WCOREDUMP 2513 packet_put_char(WCOREDUMP(status)? 1 : 0); 2514 #else /* WCOREDUMP */ 2515 packet_put_char(0); 2516 #endif /* WCOREDUMP */ 2517 packet_put_cstring(""); 2518 packet_put_cstring(""); 2519 packet_send(); 2520 } else { 2521 /* Some weird exit cause. Just exit. */ 2522 packet_disconnect("wait returned status %04x.", status); 2523 } 2524 2525 /* disconnect channel */ 2526 debug("session_exit_message: release channel %d", s->chanid); 2527 2528 /* 2529 * Adjust cleanup callback attachment to send close messages when 2530 * the channel gets EOF. The session will be then be closed 2531 * by session_close_by_channel when the childs close their fds. 2532 */ 2533 channel_register_cleanup(c->self, session_close_by_channel, 1); 2534 2535 /* 2536 * emulate a write failure with 'chan_write_failed', nobody will be 2537 * interested in data we write. 2538 * Note that we must not call 'chan_read_failed', since there could 2539 * be some more data waiting in the pipe. 2540 */ 2541 if (c->ostate != CHAN_OUTPUT_CLOSED) 2542 chan_write_failed(c); 2543 } 2544 2545 void 2546 session_close(Session *s) 2547 { 2548 u_int i; 2549 2550 debug("session_close: session %d pid %ld", s->self, (long)s->pid); 2551 if (s->ttyfd != -1) 2552 session_pty_cleanup(s); 2553 free(s->term); 2554 free(s->display); 2555 free(s->x11_chanids); 2556 free(s->auth_display); 2557 free(s->auth_data); 2558 free(s->auth_proto); 2559 free(s->subsys); 2560 if (s->env != NULL) { 2561 for (i = 0; i < s->num_env; i++) { 2562 free(s->env[i].name); 2563 free(s->env[i].val); 2564 } 2565 free(s->env); 2566 } 2567 session_proctitle(s); 2568 session_unused(s->self); 2569 } 2570 2571 void 2572 session_close_by_pid(pid_t pid, int status) 2573 { 2574 Session *s = session_by_pid(pid); 2575 if (s == NULL) { 2576 debug("session_close_by_pid: no session for pid %ld", 2577 (long)pid); 2578 return; 2579 } 2580 if (s->chanid != -1) 2581 session_exit_message(s, status); 2582 if (s->ttyfd != -1) 2583 session_pty_cleanup(s); 2584 s->pid = 0; 2585 } 2586 2587 /* 2588 * this is called when a channel dies before 2589 * the session 'child' itself dies 2590 */ 2591 void 2592 session_close_by_channel(int id, void *arg) 2593 { 2594 Session *s = session_by_channel(id); 2595 u_int i; 2596 2597 if (s == NULL) { 2598 debug("session_close_by_channel: no session for id %d", id); 2599 return; 2600 } 2601 debug("session_close_by_channel: channel %d child %ld", 2602 id, (long)s->pid); 2603 if (s->pid != 0) { 2604 debug("session_close_by_channel: channel %d: has child", id); 2605 /* 2606 * delay detach of session, but release pty, since 2607 * the fd's to the child are already closed 2608 */ 2609 if (s->ttyfd != -1) 2610 session_pty_cleanup(s); 2611 return; 2612 } 2613 /* detach by removing callback */ 2614 channel_cancel_cleanup(s->chanid); 2615 2616 /* Close any X11 listeners associated with this session */ 2617 if (s->x11_chanids != NULL) { 2618 for (i = 0; s->x11_chanids[i] != -1; i++) { 2619 session_close_x11(s->x11_chanids[i]); 2620 s->x11_chanids[i] = -1; 2621 } 2622 } 2623 2624 s->chanid = -1; 2625 session_close(s); 2626 } 2627 2628 void 2629 session_destroy_all(void (*closefunc)(Session *)) 2630 { 2631 int i; 2632 for (i = 0; i < sessions_nalloc; i++) { 2633 Session *s = &sessions[i]; 2634 if (s->used) { 2635 if (closefunc != NULL) 2636 closefunc(s); 2637 else 2638 session_close(s); 2639 } 2640 } 2641 } 2642 2643 static char * 2644 session_tty_list(void) 2645 { 2646 static char buf[1024]; 2647 int i; 2648 char *cp; 2649 2650 buf[0] = '\0'; 2651 for (i = 0; i < sessions_nalloc; i++) { 2652 Session *s = &sessions[i]; 2653 if (s->used && s->ttyfd != -1) { 2654 2655 if (strncmp(s->tty, "/dev/", 5) != 0) { 2656 cp = strrchr(s->tty, '/'); 2657 cp = (cp == NULL) ? s->tty : cp + 1; 2658 } else 2659 cp = s->tty + 5; 2660 2661 if (buf[0] != '\0') 2662 strlcat(buf, ",", sizeof buf); 2663 strlcat(buf, cp, sizeof buf); 2664 } 2665 } 2666 if (buf[0] == '\0') 2667 strlcpy(buf, "notty", sizeof buf); 2668 return buf; 2669 } 2670 2671 void 2672 session_proctitle(Session *s) 2673 { 2674 if (s->pw == NULL) 2675 error("no user for session %d", s->self); 2676 else 2677 setproctitle("%s@%s", s->pw->pw_name, session_tty_list()); 2678 } 2679 2680 int 2681 session_setup_x11fwd(Session *s) 2682 { 2683 struct stat st; 2684 char display[512], auth_display[512]; 2685 char hostname[NI_MAXHOST]; 2686 u_int i; 2687 2688 if (no_x11_forwarding_flag) { 2689 packet_send_debug("X11 forwarding disabled in user configuration file."); 2690 return 0; 2691 } 2692 if (!options.x11_forwarding) { 2693 debug("X11 forwarding disabled in server configuration file."); 2694 return 0; 2695 } 2696 if (!options.xauth_location || 2697 (stat(options.xauth_location, &st) == -1)) { 2698 packet_send_debug("No xauth program; cannot forward with spoofing."); 2699 return 0; 2700 } 2701 if (options.use_login) { 2702 packet_send_debug("X11 forwarding disabled; " 2703 "not compatible with UseLogin=yes."); 2704 return 0; 2705 } 2706 if (s->display != NULL) { 2707 debug("X11 display already set."); 2708 return 0; 2709 } 2710 if (x11_create_display_inet(options.x11_display_offset, 2711 options.x11_use_localhost, s->single_connection, 2712 &s->display_number, &s->x11_chanids) == -1) { 2713 debug("x11_create_display_inet failed."); 2714 return 0; 2715 } 2716 for (i = 0; s->x11_chanids[i] != -1; i++) { 2717 channel_register_cleanup(s->x11_chanids[i], 2718 session_close_single_x11, 0); 2719 } 2720 2721 /* Set up a suitable value for the DISPLAY variable. */ 2722 if (gethostname(hostname, sizeof(hostname)) < 0) 2723 fatal("gethostname: %.100s", strerror(errno)); 2724 /* 2725 * auth_display must be used as the displayname when the 2726 * authorization entry is added with xauth(1). This will be 2727 * different than the DISPLAY string for localhost displays. 2728 */ 2729 if (options.x11_use_localhost) { 2730 snprintf(display, sizeof display, "localhost:%u.%u", 2731 s->display_number, s->screen); 2732 snprintf(auth_display, sizeof auth_display, "unix:%u.%u", 2733 s->display_number, s->screen); 2734 s->display = xstrdup(display); 2735 s->auth_display = xstrdup(auth_display); 2736 } else { 2737 #ifdef IPADDR_IN_DISPLAY 2738 struct hostent *he; 2739 struct in_addr my_addr; 2740 2741 he = gethostbyname(hostname); 2742 if (he == NULL) { 2743 error("Can't get IP address for X11 DISPLAY."); 2744 packet_send_debug("Can't get IP address for X11 DISPLAY."); 2745 return 0; 2746 } 2747 memcpy(&my_addr, he->h_addr_list[0], sizeof(struct in_addr)); 2748 snprintf(display, sizeof display, "%.50s:%u.%u", inet_ntoa(my_addr), 2749 s->display_number, s->screen); 2750 #else 2751 snprintf(display, sizeof display, "%.400s:%u.%u", hostname, 2752 s->display_number, s->screen); 2753 #endif 2754 s->display = xstrdup(display); 2755 s->auth_display = xstrdup(display); 2756 } 2757 2758 return 1; 2759 } 2760 2761 static void 2762 do_authenticated2(Authctxt *authctxt) 2763 { 2764 server_loop2(authctxt); 2765 } 2766 2767 void 2768 do_cleanup(Authctxt *authctxt) 2769 { 2770 static int called = 0; 2771 2772 debug("do_cleanup"); 2773 2774 /* no cleanup if we're in the child for login shell */ 2775 if (is_child) 2776 return; 2777 2778 /* avoid double cleanup */ 2779 if (called) 2780 return; 2781 called = 1; 2782 2783 if (authctxt == NULL) 2784 return; 2785 2786 #ifdef USE_PAM 2787 if (options.use_pam) { 2788 sshpam_cleanup(); 2789 sshpam_thread_cleanup(); 2790 } 2791 #endif 2792 2793 if (!authctxt->authenticated) 2794 return; 2795 2796 #ifdef KRB5 2797 if (options.kerberos_ticket_cleanup && 2798 authctxt->krb5_ctx) 2799 krb5_cleanup_proc(authctxt); 2800 #endif 2801 2802 #ifdef GSSAPI 2803 if (compat20 && options.gss_cleanup_creds) 2804 ssh_gssapi_cleanup_creds(); 2805 #endif 2806 2807 /* remove agent socket */ 2808 auth_sock_cleanup_proc(authctxt->pw); 2809 2810 /* 2811 * Cleanup ptys/utmp only if privsep is disabled, 2812 * or if running in monitor. 2813 */ 2814 if (!use_privsep || mm_is_monitor()) 2815 session_destroy_all(session_pty_cleanup2); 2816 } 2817