1 /* $OpenBSD: session.c,v 1.256 2010/06/25 07:20:04 djm Exp $ */ 2 /* 3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 4 * All rights reserved 5 * 6 * As far as I am concerned, the code I have written for this software 7 * can be used freely for any purpose. Any derived versions of this 8 * software must be clearly marked as such, and if the derived work is 9 * incompatible with the protocol description in the RFC file, it must be 10 * called by a name other than "ssh" or "Secure Shell". 11 * 12 * SSH2 support by Markus Friedl. 13 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 14 * 15 * Redistribution and use in source and binary forms, with or without 16 * modification, are permitted provided that the following conditions 17 * are met: 18 * 1. Redistributions of source code must retain the above copyright 19 * notice, this list of conditions and the following disclaimer. 20 * 2. Redistributions in binary form must reproduce the above copyright 21 * notice, this list of conditions and the following disclaimer in the 22 * documentation and/or other materials provided with the distribution. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 25 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 26 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 27 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 28 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 29 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 30 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 31 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 32 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 33 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 34 */ 35 36 #include "includes.h" 37 __RCSID("$FreeBSD$"); 38 39 #include <sys/types.h> 40 #include <sys/param.h> 41 #ifdef HAVE_SYS_STAT_H 42 # include <sys/stat.h> 43 #endif 44 #include <sys/socket.h> 45 #include <sys/un.h> 46 #include <sys/wait.h> 47 48 #include <arpa/inet.h> 49 50 #include <errno.h> 51 #include <fcntl.h> 52 #include <grp.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 "pathnames.h" 85 #include "log.h" 86 #include "servconf.h" 87 #include "sshlogin.h" 88 #include "serverloop.h" 89 #include "canohost.h" 90 #include "misc.h" 91 #include "session.h" 92 #include "kex.h" 93 #include "monitor_wrap.h" 94 #include "sftp.h" 95 96 #if defined(KRB5) && defined(USE_AFS) 97 #include <kafs.h> 98 #endif 99 100 #define IS_INTERNAL_SFTP(c) \ 101 (!strncmp(c, INTERNAL_SFTP_NAME, sizeof(INTERNAL_SFTP_NAME) - 1) && \ 102 (c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\0' || \ 103 c[sizeof(INTERNAL_SFTP_NAME) - 1] == ' ' || \ 104 c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\t')) 105 106 /* func */ 107 108 Session *session_new(void); 109 void session_set_fds(Session *, int, int, int, int, int); 110 void session_pty_cleanup(Session *); 111 void session_proctitle(Session *); 112 int session_setup_x11fwd(Session *); 113 int do_exec_pty(Session *, const char *); 114 int do_exec_no_pty(Session *, const char *); 115 int do_exec(Session *, const char *); 116 void do_login(Session *, const char *); 117 #ifdef LOGIN_NEEDS_UTMPX 118 static void do_pre_login(Session *s); 119 #endif 120 void do_child(Session *, const char *); 121 void do_motd(void); 122 int check_quietlogin(Session *, const char *); 123 124 static void do_authenticated1(Authctxt *); 125 static void do_authenticated2(Authctxt *); 126 127 static int session_pty_req(Session *); 128 129 /* import */ 130 extern ServerOptions options; 131 extern char *__progname; 132 extern int log_stderr; 133 extern int debug_flag; 134 extern u_int utmp_len; 135 extern int startup_pipe; 136 extern void destroy_sensitive_data(void); 137 extern Buffer loginmsg; 138 139 /* original command from peer. */ 140 const char *original_command = NULL; 141 142 /* data */ 143 static int sessions_first_unused = -1; 144 static int sessions_nalloc = 0; 145 static Session *sessions = NULL; 146 147 #define SUBSYSTEM_NONE 0 148 #define SUBSYSTEM_EXT 1 149 #define SUBSYSTEM_INT_SFTP 2 150 #define SUBSYSTEM_INT_SFTP_ERROR 3 151 152 #ifdef HAVE_LOGIN_CAP 153 login_cap_t *lc; 154 #endif 155 156 static int is_child = 0; 157 158 /* Name and directory of socket for authentication agent forwarding. */ 159 static char *auth_sock_name = NULL; 160 static char *auth_sock_dir = NULL; 161 162 /* removes the agent forwarding socket */ 163 164 static void 165 auth_sock_cleanup_proc(struct passwd *pw) 166 { 167 if (auth_sock_name != NULL) { 168 temporarily_use_uid(pw); 169 unlink(auth_sock_name); 170 rmdir(auth_sock_dir); 171 auth_sock_name = NULL; 172 restore_uid(); 173 } 174 } 175 176 static int 177 auth_input_request_forwarding(struct passwd * pw) 178 { 179 Channel *nc; 180 int sock = -1; 181 struct sockaddr_un sunaddr; 182 183 if (auth_sock_name != NULL) { 184 error("authentication forwarding requested twice."); 185 return 0; 186 } 187 188 /* Temporarily drop privileged uid for mkdir/bind. */ 189 temporarily_use_uid(pw); 190 191 /* Allocate a buffer for the socket name, and format the name. */ 192 auth_sock_dir = xstrdup("/tmp/ssh-XXXXXXXXXX"); 193 194 /* Create private directory for socket */ 195 if (mkdtemp(auth_sock_dir) == NULL) { 196 packet_send_debug("Agent forwarding disabled: " 197 "mkdtemp() failed: %.100s", strerror(errno)); 198 restore_uid(); 199 xfree(auth_sock_dir); 200 auth_sock_dir = NULL; 201 goto authsock_err; 202 } 203 204 xasprintf(&auth_sock_name, "%s/agent.%ld", 205 auth_sock_dir, (long) getpid()); 206 207 /* Create the socket. */ 208 sock = socket(AF_UNIX, SOCK_STREAM, 0); 209 if (sock < 0) { 210 error("socket: %.100s", strerror(errno)); 211 restore_uid(); 212 goto authsock_err; 213 } 214 215 /* Bind it to the name. */ 216 memset(&sunaddr, 0, sizeof(sunaddr)); 217 sunaddr.sun_family = AF_UNIX; 218 strlcpy(sunaddr.sun_path, auth_sock_name, sizeof(sunaddr.sun_path)); 219 220 if (bind(sock, (struct sockaddr *)&sunaddr, sizeof(sunaddr)) < 0) { 221 error("bind: %.100s", strerror(errno)); 222 restore_uid(); 223 goto authsock_err; 224 } 225 226 /* Restore the privileged uid. */ 227 restore_uid(); 228 229 /* Start listening on the socket. */ 230 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) { 231 error("listen: %.100s", strerror(errno)); 232 goto authsock_err; 233 } 234 235 /* Allocate a channel for the authentication agent socket. */ 236 nc = channel_new("auth socket", 237 SSH_CHANNEL_AUTH_SOCKET, sock, sock, -1, 238 CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 239 0, "auth socket", 1); 240 nc->path = xstrdup(auth_sock_name); 241 return 1; 242 243 authsock_err: 244 if (auth_sock_name != NULL) 245 xfree(auth_sock_name); 246 if (auth_sock_dir != NULL) { 247 rmdir(auth_sock_dir); 248 xfree(auth_sock_dir); 249 } 250 if (sock != -1) 251 close(sock); 252 auth_sock_name = NULL; 253 auth_sock_dir = NULL; 254 return 0; 255 } 256 257 static void 258 display_loginmsg(void) 259 { 260 if (buffer_len(&loginmsg) > 0) { 261 buffer_append(&loginmsg, "\0", 1); 262 printf("%s", (char *)buffer_ptr(&loginmsg)); 263 buffer_clear(&loginmsg); 264 } 265 } 266 267 void 268 do_authenticated(Authctxt *authctxt) 269 { 270 setproctitle("%s", authctxt->pw->pw_name); 271 272 /* setup the channel layer */ 273 if (!no_port_forwarding_flag && options.allow_tcp_forwarding) 274 channel_permit_all_opens(); 275 276 auth_debug_send(); 277 278 if (compat20) 279 do_authenticated2(authctxt); 280 else 281 do_authenticated1(authctxt); 282 283 do_cleanup(authctxt); 284 } 285 286 /* 287 * Prepares for an interactive session. This is called after the user has 288 * been successfully authenticated. During this message exchange, pseudo 289 * terminals are allocated, X11, TCP/IP, and authentication agent forwardings 290 * are requested, etc. 291 */ 292 static void 293 do_authenticated1(Authctxt *authctxt) 294 { 295 Session *s; 296 char *command; 297 int success, type, screen_flag; 298 int enable_compression_after_reply = 0; 299 u_int proto_len, data_len, dlen, compression_level = 0; 300 301 s = session_new(); 302 if (s == NULL) { 303 error("no more sessions"); 304 return; 305 } 306 s->authctxt = authctxt; 307 s->pw = authctxt->pw; 308 309 /* 310 * We stay in this loop until the client requests to execute a shell 311 * or a command. 312 */ 313 for (;;) { 314 success = 0; 315 316 /* Get a packet from the client. */ 317 type = packet_read(); 318 319 /* Process the packet. */ 320 switch (type) { 321 case SSH_CMSG_REQUEST_COMPRESSION: 322 compression_level = packet_get_int(); 323 packet_check_eom(); 324 if (compression_level < 1 || compression_level > 9) { 325 packet_send_debug("Received invalid compression level %d.", 326 compression_level); 327 break; 328 } 329 if (options.compression == COMP_NONE) { 330 debug2("compression disabled"); 331 break; 332 } 333 /* Enable compression after we have responded with SUCCESS. */ 334 enable_compression_after_reply = 1; 335 success = 1; 336 break; 337 338 case SSH_CMSG_REQUEST_PTY: 339 success = session_pty_req(s); 340 break; 341 342 case SSH_CMSG_X11_REQUEST_FORWARDING: 343 s->auth_proto = packet_get_string(&proto_len); 344 s->auth_data = packet_get_string(&data_len); 345 346 screen_flag = packet_get_protocol_flags() & 347 SSH_PROTOFLAG_SCREEN_NUMBER; 348 debug2("SSH_PROTOFLAG_SCREEN_NUMBER: %d", screen_flag); 349 350 if (packet_remaining() == 4) { 351 if (!screen_flag) 352 debug2("Buggy client: " 353 "X11 screen flag missing"); 354 s->screen = packet_get_int(); 355 } else { 356 s->screen = 0; 357 } 358 packet_check_eom(); 359 success = session_setup_x11fwd(s); 360 if (!success) { 361 xfree(s->auth_proto); 362 xfree(s->auth_data); 363 s->auth_proto = NULL; 364 s->auth_data = NULL; 365 } 366 break; 367 368 case SSH_CMSG_AGENT_REQUEST_FORWARDING: 369 if (!options.allow_agent_forwarding || 370 no_agent_forwarding_flag || compat13) { 371 debug("Authentication agent forwarding not permitted for this authentication."); 372 break; 373 } 374 debug("Received authentication agent forwarding request."); 375 success = auth_input_request_forwarding(s->pw); 376 break; 377 378 case SSH_CMSG_PORT_FORWARD_REQUEST: 379 if (no_port_forwarding_flag) { 380 debug("Port forwarding not permitted for this authentication."); 381 break; 382 } 383 if (!options.allow_tcp_forwarding) { 384 debug("Port forwarding not permitted."); 385 break; 386 } 387 debug("Received TCP/IP port forwarding request."); 388 if (channel_input_port_forward_request(s->pw->pw_uid == 0, 389 options.gateway_ports) < 0) { 390 debug("Port forwarding failed."); 391 break; 392 } 393 success = 1; 394 break; 395 396 case SSH_CMSG_MAX_PACKET_SIZE: 397 if (packet_set_maxsize(packet_get_int()) > 0) 398 success = 1; 399 break; 400 401 case SSH_CMSG_EXEC_SHELL: 402 case SSH_CMSG_EXEC_CMD: 403 if (type == SSH_CMSG_EXEC_CMD) { 404 command = packet_get_string(&dlen); 405 debug("Exec command '%.500s'", command); 406 if (do_exec(s, command) != 0) 407 packet_disconnect( 408 "command execution failed"); 409 xfree(command); 410 } else { 411 if (do_exec(s, NULL) != 0) 412 packet_disconnect( 413 "shell execution failed"); 414 } 415 packet_check_eom(); 416 session_close(s); 417 return; 418 419 default: 420 /* 421 * Any unknown messages in this phase are ignored, 422 * and a failure message is returned. 423 */ 424 logit("Unknown packet type received after authentication: %d", type); 425 } 426 packet_start(success ? SSH_SMSG_SUCCESS : SSH_SMSG_FAILURE); 427 packet_send(); 428 packet_write_wait(); 429 430 /* Enable compression now that we have replied if appropriate. */ 431 if (enable_compression_after_reply) { 432 enable_compression_after_reply = 0; 433 packet_start_compression(compression_level); 434 } 435 } 436 } 437 438 #define USE_PIPES 439 /* 440 * This is called to fork and execute a command when we have no tty. This 441 * will call do_child from the child, and server_loop from the parent after 442 * setting up file descriptors and such. 443 */ 444 int 445 do_exec_no_pty(Session *s, const char *command) 446 { 447 pid_t pid; 448 449 #ifdef USE_PIPES 450 int pin[2], pout[2], perr[2]; 451 452 if (s == NULL) 453 fatal("do_exec_no_pty: no session"); 454 455 /* Allocate pipes for communicating with the program. */ 456 if (pipe(pin) < 0) { 457 error("%s: pipe in: %.100s", __func__, strerror(errno)); 458 return -1; 459 } 460 if (pipe(pout) < 0) { 461 error("%s: pipe out: %.100s", __func__, strerror(errno)); 462 close(pin[0]); 463 close(pin[1]); 464 return -1; 465 } 466 if (pipe(perr) < 0) { 467 error("%s: pipe err: %.100s", __func__, 468 strerror(errno)); 469 close(pin[0]); 470 close(pin[1]); 471 close(pout[0]); 472 close(pout[1]); 473 return -1; 474 } 475 #else 476 int inout[2], err[2]; 477 478 if (s == NULL) 479 fatal("do_exec_no_pty: no session"); 480 481 /* Uses socket pairs to communicate with the program. */ 482 if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) < 0) { 483 error("%s: socketpair #1: %.100s", __func__, strerror(errno)); 484 return -1; 485 } 486 if (socketpair(AF_UNIX, SOCK_STREAM, 0, err) < 0) { 487 error("%s: socketpair #2: %.100s", __func__, 488 strerror(errno)); 489 close(inout[0]); 490 close(inout[1]); 491 return -1; 492 } 493 #endif 494 495 session_proctitle(s); 496 497 /* Fork the child. */ 498 switch ((pid = fork())) { 499 case -1: 500 error("%s: fork: %.100s", __func__, strerror(errno)); 501 #ifdef USE_PIPES 502 close(pin[0]); 503 close(pin[1]); 504 close(pout[0]); 505 close(pout[1]); 506 close(perr[0]); 507 close(perr[1]); 508 #else 509 close(inout[0]); 510 close(inout[1]); 511 close(err[0]); 512 close(err[1]); 513 #endif 514 return -1; 515 case 0: 516 is_child = 1; 517 518 /* Child. Reinitialize the log since the pid has changed. */ 519 log_init(__progname, options.log_level, 520 options.log_facility, log_stderr); 521 522 /* 523 * Create a new session and process group since the 4.4BSD 524 * setlogin() affects the entire process group. 525 */ 526 if (setsid() < 0) 527 error("setsid failed: %.100s", strerror(errno)); 528 529 #ifdef USE_PIPES 530 /* 531 * Redirect stdin. We close the parent side of the socket 532 * pair, and make the child side the standard input. 533 */ 534 close(pin[1]); 535 if (dup2(pin[0], 0) < 0) 536 perror("dup2 stdin"); 537 close(pin[0]); 538 539 /* Redirect stdout. */ 540 close(pout[0]); 541 if (dup2(pout[1], 1) < 0) 542 perror("dup2 stdout"); 543 close(pout[1]); 544 545 /* Redirect stderr. */ 546 close(perr[0]); 547 if (dup2(perr[1], 2) < 0) 548 perror("dup2 stderr"); 549 close(perr[1]); 550 #else 551 /* 552 * Redirect stdin, stdout, and stderr. Stdin and stdout will 553 * use the same socket, as some programs (particularly rdist) 554 * seem to depend on it. 555 */ 556 close(inout[1]); 557 close(err[1]); 558 if (dup2(inout[0], 0) < 0) /* stdin */ 559 perror("dup2 stdin"); 560 if (dup2(inout[0], 1) < 0) /* stdout (same as stdin) */ 561 perror("dup2 stdout"); 562 close(inout[0]); 563 if (dup2(err[0], 2) < 0) /* stderr */ 564 perror("dup2 stderr"); 565 close(err[0]); 566 #endif 567 568 569 #ifdef _UNICOS 570 cray_init_job(s->pw); /* set up cray jid and tmpdir */ 571 #endif 572 573 /* Do processing for the child (exec command etc). */ 574 do_child(s, command); 575 /* NOTREACHED */ 576 default: 577 break; 578 } 579 580 #ifdef _UNICOS 581 signal(WJSIGNAL, cray_job_termination_handler); 582 #endif /* _UNICOS */ 583 #ifdef HAVE_CYGWIN 584 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); 585 #endif 586 587 s->pid = pid; 588 /* Set interactive/non-interactive mode. */ 589 packet_set_interactive(s->display != NULL); 590 591 /* 592 * Clear loginmsg, since it's the child's responsibility to display 593 * it to the user, otherwise multiple sessions may accumulate 594 * multiple copies of the login messages. 595 */ 596 buffer_clear(&loginmsg); 597 598 #ifdef USE_PIPES 599 /* We are the parent. Close the child sides of the pipes. */ 600 close(pin[0]); 601 close(pout[1]); 602 close(perr[1]); 603 604 if (compat20) { 605 session_set_fds(s, pin[1], pout[0], perr[0], 606 s->is_subsystem, 0); 607 } else { 608 /* Enter the interactive session. */ 609 server_loop(pid, pin[1], pout[0], perr[0]); 610 /* server_loop has closed pin[1], pout[0], and perr[0]. */ 611 } 612 #else 613 /* We are the parent. Close the child sides of the socket pairs. */ 614 close(inout[0]); 615 close(err[0]); 616 617 /* 618 * Enter the interactive session. Note: server_loop must be able to 619 * handle the case that fdin and fdout are the same. 620 */ 621 if (compat20) { 622 session_set_fds(s, inout[1], inout[1], err[1], 623 s->is_subsystem, 0); 624 } else { 625 server_loop(pid, inout[1], inout[1], err[1]); 626 /* server_loop has closed inout[1] and err[1]. */ 627 } 628 #endif 629 return 0; 630 } 631 632 /* 633 * This is called to fork and execute a command when we have a tty. This 634 * will call do_child from the child, and server_loop from the parent after 635 * setting up file descriptors, controlling tty, updating wtmp, utmp, 636 * lastlog, and other such operations. 637 */ 638 int 639 do_exec_pty(Session *s, const char *command) 640 { 641 int fdout, ptyfd, ttyfd, ptymaster; 642 pid_t pid; 643 644 if (s == NULL) 645 fatal("do_exec_pty: no session"); 646 ptyfd = s->ptyfd; 647 ttyfd = s->ttyfd; 648 649 /* 650 * Create another descriptor of the pty master side for use as the 651 * standard input. We could use the original descriptor, but this 652 * simplifies code in server_loop. The descriptor is bidirectional. 653 * Do this before forking (and cleanup in the child) so as to 654 * detect and gracefully fail out-of-fd conditions. 655 */ 656 if ((fdout = dup(ptyfd)) < 0) { 657 error("%s: dup #1: %s", __func__, strerror(errno)); 658 close(ttyfd); 659 close(ptyfd); 660 return -1; 661 } 662 /* we keep a reference to the pty master */ 663 if ((ptymaster = dup(ptyfd)) < 0) { 664 error("%s: dup #2: %s", __func__, strerror(errno)); 665 close(ttyfd); 666 close(ptyfd); 667 close(fdout); 668 return -1; 669 } 670 671 /* Fork the child. */ 672 switch ((pid = fork())) { 673 case -1: 674 error("%s: fork: %.100s", __func__, strerror(errno)); 675 close(fdout); 676 close(ptymaster); 677 close(ttyfd); 678 close(ptyfd); 679 return -1; 680 case 0: 681 is_child = 1; 682 683 close(fdout); 684 close(ptymaster); 685 686 /* Child. Reinitialize the log because the pid has changed. */ 687 log_init(__progname, options.log_level, 688 options.log_facility, log_stderr); 689 /* Close the master side of the pseudo tty. */ 690 close(ptyfd); 691 692 /* Make the pseudo tty our controlling tty. */ 693 pty_make_controlling_tty(&ttyfd, s->tty); 694 695 /* Redirect stdin/stdout/stderr from the pseudo tty. */ 696 if (dup2(ttyfd, 0) < 0) 697 error("dup2 stdin: %s", strerror(errno)); 698 if (dup2(ttyfd, 1) < 0) 699 error("dup2 stdout: %s", strerror(errno)); 700 if (dup2(ttyfd, 2) < 0) 701 error("dup2 stderr: %s", strerror(errno)); 702 703 /* Close the extra descriptor for the pseudo tty. */ 704 close(ttyfd); 705 706 /* record login, etc. similar to login(1) */ 707 #ifndef HAVE_OSF_SIA 708 if (!(options.use_login && command == NULL)) { 709 #ifdef _UNICOS 710 cray_init_job(s->pw); /* set up cray jid and tmpdir */ 711 #endif /* _UNICOS */ 712 do_login(s, command); 713 } 714 # ifdef LOGIN_NEEDS_UTMPX 715 else 716 do_pre_login(s); 717 # endif 718 #endif 719 /* 720 * Do common processing for the child, such as execing 721 * the command. 722 */ 723 do_child(s, command); 724 /* NOTREACHED */ 725 default: 726 break; 727 } 728 729 #ifdef _UNICOS 730 signal(WJSIGNAL, cray_job_termination_handler); 731 #endif /* _UNICOS */ 732 #ifdef HAVE_CYGWIN 733 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); 734 #endif 735 736 s->pid = pid; 737 738 /* Parent. Close the slave side of the pseudo tty. */ 739 close(ttyfd); 740 741 /* Enter interactive session. */ 742 s->ptymaster = ptymaster; 743 packet_set_interactive(1); 744 if (compat20) { 745 session_set_fds(s, ptyfd, fdout, -1, 1, 1); 746 } else { 747 server_loop(pid, ptyfd, fdout, -1); 748 /* server_loop _has_ closed ptyfd and fdout. */ 749 } 750 return 0; 751 } 752 753 #ifdef LOGIN_NEEDS_UTMPX 754 static void 755 do_pre_login(Session *s) 756 { 757 socklen_t fromlen; 758 struct sockaddr_storage from; 759 pid_t pid = getpid(); 760 761 /* 762 * Get IP address of client. If the connection is not a socket, let 763 * the address be 0.0.0.0. 764 */ 765 memset(&from, 0, sizeof(from)); 766 fromlen = sizeof(from); 767 if (packet_connection_is_on_socket()) { 768 if (getpeername(packet_get_connection_in(), 769 (struct sockaddr *)&from, &fromlen) < 0) { 770 debug("getpeername: %.100s", strerror(errno)); 771 cleanup_exit(255); 772 } 773 } 774 775 record_utmp_only(pid, s->tty, s->pw->pw_name, 776 get_remote_name_or_ip(utmp_len, options.use_dns), 777 (struct sockaddr *)&from, fromlen); 778 } 779 #endif 780 781 /* 782 * This is called to fork and execute a command. If another command is 783 * to be forced, execute that instead. 784 */ 785 int 786 do_exec(Session *s, const char *command) 787 { 788 int ret; 789 790 if (options.adm_forced_command) { 791 original_command = command; 792 command = options.adm_forced_command; 793 if (IS_INTERNAL_SFTP(command)) { 794 s->is_subsystem = s->is_subsystem ? 795 SUBSYSTEM_INT_SFTP : SUBSYSTEM_INT_SFTP_ERROR; 796 } else if (s->is_subsystem) 797 s->is_subsystem = SUBSYSTEM_EXT; 798 debug("Forced command (config) '%.900s'", command); 799 } else if (forced_command) { 800 original_command = command; 801 command = forced_command; 802 if (IS_INTERNAL_SFTP(command)) { 803 s->is_subsystem = s->is_subsystem ? 804 SUBSYSTEM_INT_SFTP : SUBSYSTEM_INT_SFTP_ERROR; 805 } else if (s->is_subsystem) 806 s->is_subsystem = SUBSYSTEM_EXT; 807 debug("Forced command (key option) '%.900s'", command); 808 } 809 810 #ifdef SSH_AUDIT_EVENTS 811 if (command != NULL) 812 PRIVSEP(audit_run_command(command)); 813 else if (s->ttyfd == -1) { 814 char *shell = s->pw->pw_shell; 815 816 if (shell[0] == '\0') /* empty shell means /bin/sh */ 817 shell =_PATH_BSHELL; 818 PRIVSEP(audit_run_command(shell)); 819 } 820 #endif 821 if (s->ttyfd != -1) 822 ret = do_exec_pty(s, command); 823 else 824 ret = do_exec_no_pty(s, command); 825 826 original_command = NULL; 827 828 /* 829 * Clear loginmsg: it's the child's responsibility to display 830 * it to the user, otherwise multiple sessions may accumulate 831 * multiple copies of the login messages. 832 */ 833 buffer_clear(&loginmsg); 834 835 return ret; 836 } 837 838 /* administrative, login(1)-like work */ 839 void 840 do_login(Session *s, const char *command) 841 { 842 socklen_t fromlen; 843 struct sockaddr_storage from; 844 struct passwd * pw = s->pw; 845 pid_t pid = getpid(); 846 847 /* 848 * Get IP address of client. If the connection is not a socket, let 849 * the address be 0.0.0.0. 850 */ 851 memset(&from, 0, sizeof(from)); 852 fromlen = sizeof(from); 853 if (packet_connection_is_on_socket()) { 854 if (getpeername(packet_get_connection_in(), 855 (struct sockaddr *)&from, &fromlen) < 0) { 856 debug("getpeername: %.100s", strerror(errno)); 857 cleanup_exit(255); 858 } 859 } 860 861 /* Record that there was a login on that tty from the remote host. */ 862 if (!use_privsep) 863 record_login(pid, s->tty, pw->pw_name, pw->pw_uid, 864 get_remote_name_or_ip(utmp_len, 865 options.use_dns), 866 (struct sockaddr *)&from, fromlen); 867 868 #ifdef USE_PAM 869 /* 870 * If password change is needed, do it now. 871 * This needs to occur before the ~/.hushlogin check. 872 */ 873 if (options.use_pam && !use_privsep && s->authctxt->force_pwchange) { 874 display_loginmsg(); 875 do_pam_chauthtok(); 876 s->authctxt->force_pwchange = 0; 877 /* XXX - signal [net] parent to enable forwardings */ 878 } 879 #endif 880 881 if (check_quietlogin(s, command)) 882 return; 883 884 display_loginmsg(); 885 886 do_motd(); 887 } 888 889 /* 890 * Display the message of the day. 891 */ 892 void 893 do_motd(void) 894 { 895 FILE *f; 896 char buf[256]; 897 898 if (options.print_motd) { 899 #ifdef HAVE_LOGIN_CAP 900 f = fopen(login_getcapstr(lc, "welcome", "/etc/motd", 901 "/etc/motd"), "r"); 902 #else 903 f = fopen("/etc/motd", "r"); 904 #endif 905 if (f) { 906 while (fgets(buf, sizeof(buf), f)) 907 fputs(buf, stdout); 908 fclose(f); 909 } 910 } 911 } 912 913 914 /* 915 * Check for quiet login, either .hushlogin or command given. 916 */ 917 int 918 check_quietlogin(Session *s, const char *command) 919 { 920 char buf[256]; 921 struct passwd *pw = s->pw; 922 struct stat st; 923 924 /* Return 1 if .hushlogin exists or a command given. */ 925 if (command != NULL) 926 return 1; 927 snprintf(buf, sizeof(buf), "%.200s/.hushlogin", pw->pw_dir); 928 #ifdef HAVE_LOGIN_CAP 929 if (login_getcapbool(lc, "hushlogin", 0) || stat(buf, &st) >= 0) 930 return 1; 931 #else 932 if (stat(buf, &st) >= 0) 933 return 1; 934 #endif 935 return 0; 936 } 937 938 /* 939 * Sets the value of the given variable in the environment. If the variable 940 * already exists, its value is overridden. 941 */ 942 void 943 child_set_env(char ***envp, u_int *envsizep, const char *name, 944 const char *value) 945 { 946 char **env; 947 u_int envsize; 948 u_int i, namelen; 949 950 /* 951 * If we're passed an uninitialized list, allocate a single null 952 * entry before continuing. 953 */ 954 if (*envp == NULL && *envsizep == 0) { 955 *envp = xmalloc(sizeof(char *)); 956 *envp[0] = NULL; 957 *envsizep = 1; 958 } 959 960 /* 961 * Find the slot where the value should be stored. If the variable 962 * already exists, we reuse the slot; otherwise we append a new slot 963 * at the end of the array, expanding if necessary. 964 */ 965 env = *envp; 966 namelen = strlen(name); 967 for (i = 0; env[i]; i++) 968 if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=') 969 break; 970 if (env[i]) { 971 /* Reuse the slot. */ 972 xfree(env[i]); 973 } else { 974 /* New variable. Expand if necessary. */ 975 envsize = *envsizep; 976 if (i >= envsize - 1) { 977 if (envsize >= 1000) 978 fatal("child_set_env: too many env vars"); 979 envsize += 50; 980 env = (*envp) = xrealloc(env, envsize, sizeof(char *)); 981 *envsizep = envsize; 982 } 983 /* Need to set the NULL pointer at end of array beyond the new slot. */ 984 env[i + 1] = NULL; 985 } 986 987 /* Allocate space and format the variable in the appropriate slot. */ 988 env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1); 989 snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value); 990 } 991 992 /* 993 * Reads environment variables from the given file and adds/overrides them 994 * into the environment. If the file does not exist, this does nothing. 995 * Otherwise, it must consist of empty lines, comments (line starts with '#') 996 * and assignments of the form name=value. No other forms are allowed. 997 */ 998 static void 999 read_environment_file(char ***env, u_int *envsize, 1000 const char *filename) 1001 { 1002 FILE *f; 1003 char buf[4096]; 1004 char *cp, *value; 1005 u_int lineno = 0; 1006 1007 f = fopen(filename, "r"); 1008 if (!f) 1009 return; 1010 1011 while (fgets(buf, sizeof(buf), f)) { 1012 if (++lineno > 1000) 1013 fatal("Too many lines in environment file %s", filename); 1014 for (cp = buf; *cp == ' ' || *cp == '\t'; cp++) 1015 ; 1016 if (!*cp || *cp == '#' || *cp == '\n') 1017 continue; 1018 1019 cp[strcspn(cp, "\n")] = '\0'; 1020 1021 value = strchr(cp, '='); 1022 if (value == NULL) { 1023 fprintf(stderr, "Bad line %u in %.100s\n", lineno, 1024 filename); 1025 continue; 1026 } 1027 /* 1028 * Replace the equals sign by nul, and advance value to 1029 * the value string. 1030 */ 1031 *value = '\0'; 1032 value++; 1033 child_set_env(env, envsize, cp, value); 1034 } 1035 fclose(f); 1036 } 1037 1038 #ifdef HAVE_ETC_DEFAULT_LOGIN 1039 /* 1040 * Return named variable from specified environment, or NULL if not present. 1041 */ 1042 static char * 1043 child_get_env(char **env, const char *name) 1044 { 1045 int i; 1046 size_t len; 1047 1048 len = strlen(name); 1049 for (i=0; env[i] != NULL; i++) 1050 if (strncmp(name, env[i], len) == 0 && env[i][len] == '=') 1051 return(env[i] + len + 1); 1052 return NULL; 1053 } 1054 1055 /* 1056 * Read /etc/default/login. 1057 * We pick up the PATH (or SUPATH for root) and UMASK. 1058 */ 1059 static void 1060 read_etc_default_login(char ***env, u_int *envsize, uid_t uid) 1061 { 1062 char **tmpenv = NULL, *var; 1063 u_int i, tmpenvsize = 0; 1064 u_long mask; 1065 1066 /* 1067 * We don't want to copy the whole file to the child's environment, 1068 * so we use a temporary environment and copy the variables we're 1069 * interested in. 1070 */ 1071 read_environment_file(&tmpenv, &tmpenvsize, "/etc/default/login"); 1072 1073 if (tmpenv == NULL) 1074 return; 1075 1076 if (uid == 0) 1077 var = child_get_env(tmpenv, "SUPATH"); 1078 else 1079 var = child_get_env(tmpenv, "PATH"); 1080 if (var != NULL) 1081 child_set_env(env, envsize, "PATH", var); 1082 1083 if ((var = child_get_env(tmpenv, "UMASK")) != NULL) 1084 if (sscanf(var, "%5lo", &mask) == 1) 1085 umask((mode_t)mask); 1086 1087 for (i = 0; tmpenv[i] != NULL; i++) 1088 xfree(tmpenv[i]); 1089 xfree(tmpenv); 1090 } 1091 #endif /* HAVE_ETC_DEFAULT_LOGIN */ 1092 1093 void 1094 copy_environment(char **source, char ***env, u_int *envsize) 1095 { 1096 char *var_name, *var_val; 1097 int i; 1098 1099 if (source == NULL) 1100 return; 1101 1102 for(i = 0; source[i] != NULL; i++) { 1103 var_name = xstrdup(source[i]); 1104 if ((var_val = strstr(var_name, "=")) == NULL) { 1105 xfree(var_name); 1106 continue; 1107 } 1108 *var_val++ = '\0'; 1109 1110 debug3("Copy environment: %s=%s", var_name, var_val); 1111 child_set_env(env, envsize, var_name, var_val); 1112 1113 xfree(var_name); 1114 } 1115 } 1116 1117 static char ** 1118 do_setup_env(Session *s, const char *shell) 1119 { 1120 char buf[256]; 1121 u_int i, envsize; 1122 char **env, *laddr; 1123 struct passwd *pw = s->pw; 1124 #if !defined (HAVE_LOGIN_CAP) && !defined (HAVE_CYGWIN) 1125 char *path = NULL; 1126 #else 1127 extern char **environ; 1128 char **senv, **var; 1129 #endif 1130 1131 /* Initialize the environment. */ 1132 envsize = 100; 1133 env = xcalloc(envsize, sizeof(char *)); 1134 env[0] = NULL; 1135 1136 #ifdef HAVE_CYGWIN 1137 /* 1138 * The Windows environment contains some setting which are 1139 * important for a running system. They must not be dropped. 1140 */ 1141 { 1142 char **p; 1143 1144 p = fetch_windows_environment(); 1145 copy_environment(p, &env, &envsize); 1146 free_windows_environment(p); 1147 } 1148 #endif 1149 1150 if (getenv("TZ")) 1151 child_set_env(&env, &envsize, "TZ", getenv("TZ")); 1152 1153 #ifdef GSSAPI 1154 /* Allow any GSSAPI methods that we've used to alter 1155 * the childs environment as they see fit 1156 */ 1157 ssh_gssapi_do_child(&env, &envsize); 1158 #endif 1159 1160 if (!options.use_login) { 1161 /* Set basic environment. */ 1162 for (i = 0; i < s->num_env; i++) 1163 child_set_env(&env, &envsize, s->env[i].name, 1164 s->env[i].val); 1165 1166 child_set_env(&env, &envsize, "USER", pw->pw_name); 1167 child_set_env(&env, &envsize, "LOGNAME", pw->pw_name); 1168 #ifdef _AIX 1169 child_set_env(&env, &envsize, "LOGIN", pw->pw_name); 1170 #endif 1171 child_set_env(&env, &envsize, "HOME", pw->pw_dir); 1172 snprintf(buf, sizeof buf, "%.200s/%.50s", 1173 _PATH_MAILDIR, pw->pw_name); 1174 child_set_env(&env, &envsize, "MAIL", buf); 1175 #ifdef HAVE_LOGIN_CAP 1176 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); 1177 child_set_env(&env, &envsize, "TERM", "su"); 1178 senv = environ; 1179 environ = xmalloc(sizeof(char *)); 1180 *environ = NULL; 1181 (void) setusercontext(lc, pw, pw->pw_uid, 1182 LOGIN_SETENV|LOGIN_SETPATH); 1183 copy_environment(environ, &env, &envsize); 1184 for (var = environ; *var != NULL; ++var) 1185 xfree(*var); 1186 xfree(environ); 1187 environ = senv; 1188 #else /* HAVE_LOGIN_CAP */ 1189 # ifndef HAVE_CYGWIN 1190 /* 1191 * There's no standard path on Windows. The path contains 1192 * important components pointing to the system directories, 1193 * needed for loading shared libraries. So the path better 1194 * remains intact here. 1195 */ 1196 # ifdef HAVE_ETC_DEFAULT_LOGIN 1197 read_etc_default_login(&env, &envsize, pw->pw_uid); 1198 path = child_get_env(env, "PATH"); 1199 # endif /* HAVE_ETC_DEFAULT_LOGIN */ 1200 if (path == NULL || *path == '\0') { 1201 child_set_env(&env, &envsize, "PATH", 1202 s->pw->pw_uid == 0 ? 1203 SUPERUSER_PATH : _PATH_STDPATH); 1204 } 1205 # endif /* HAVE_CYGWIN */ 1206 #endif /* HAVE_LOGIN_CAP */ 1207 1208 /* Normal systems set SHELL by default. */ 1209 child_set_env(&env, &envsize, "SHELL", shell); 1210 } 1211 1212 /* Set custom environment options from RSA authentication. */ 1213 if (!options.use_login) { 1214 while (custom_environment) { 1215 struct envstring *ce = custom_environment; 1216 char *str = ce->s; 1217 1218 for (i = 0; str[i] != '=' && str[i]; i++) 1219 ; 1220 if (str[i] == '=') { 1221 str[i] = 0; 1222 child_set_env(&env, &envsize, str, str + i + 1); 1223 } 1224 custom_environment = ce->next; 1225 xfree(ce->s); 1226 xfree(ce); 1227 } 1228 } 1229 1230 /* SSH_CLIENT deprecated */ 1231 snprintf(buf, sizeof buf, "%.50s %d %d", 1232 get_remote_ipaddr(), get_remote_port(), get_local_port()); 1233 child_set_env(&env, &envsize, "SSH_CLIENT", buf); 1234 1235 laddr = get_local_ipaddr(packet_get_connection_in()); 1236 snprintf(buf, sizeof buf, "%.50s %d %.50s %d", 1237 get_remote_ipaddr(), get_remote_port(), laddr, get_local_port()); 1238 xfree(laddr); 1239 child_set_env(&env, &envsize, "SSH_CONNECTION", buf); 1240 1241 if (s->ttyfd != -1) 1242 child_set_env(&env, &envsize, "SSH_TTY", s->tty); 1243 if (s->term) 1244 child_set_env(&env, &envsize, "TERM", s->term); 1245 if (s->display) 1246 child_set_env(&env, &envsize, "DISPLAY", s->display); 1247 if (original_command) 1248 child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND", 1249 original_command); 1250 1251 #ifdef _UNICOS 1252 if (cray_tmpdir[0] != '\0') 1253 child_set_env(&env, &envsize, "TMPDIR", cray_tmpdir); 1254 #endif /* _UNICOS */ 1255 1256 /* 1257 * Since we clear KRB5CCNAME at startup, if it's set now then it 1258 * must have been set by a native authentication method (eg AIX or 1259 * SIA), so copy it to the child. 1260 */ 1261 { 1262 char *cp; 1263 1264 if ((cp = getenv("KRB5CCNAME")) != NULL) 1265 child_set_env(&env, &envsize, "KRB5CCNAME", cp); 1266 } 1267 1268 #ifdef _AIX 1269 { 1270 char *cp; 1271 1272 if ((cp = getenv("AUTHSTATE")) != NULL) 1273 child_set_env(&env, &envsize, "AUTHSTATE", cp); 1274 read_environment_file(&env, &envsize, "/etc/environment"); 1275 } 1276 #endif 1277 #ifdef KRB5 1278 if (s->authctxt->krb5_ccname) 1279 child_set_env(&env, &envsize, "KRB5CCNAME", 1280 s->authctxt->krb5_ccname); 1281 #endif 1282 #ifdef USE_PAM 1283 /* 1284 * Pull in any environment variables that may have 1285 * been set by PAM. 1286 */ 1287 if (options.use_pam) { 1288 char **p; 1289 1290 p = fetch_pam_child_environment(); 1291 copy_environment(p, &env, &envsize); 1292 free_pam_environment(p); 1293 1294 p = fetch_pam_environment(); 1295 copy_environment(p, &env, &envsize); 1296 free_pam_environment(p); 1297 } 1298 #endif /* USE_PAM */ 1299 1300 if (auth_sock_name != NULL) 1301 child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME, 1302 auth_sock_name); 1303 1304 /* read $HOME/.ssh/environment. */ 1305 if (options.permit_user_env && !options.use_login) { 1306 snprintf(buf, sizeof buf, "%.200s/.ssh/environment", 1307 strcmp(pw->pw_dir, "/") ? pw->pw_dir : ""); 1308 read_environment_file(&env, &envsize, buf); 1309 } 1310 if (debug_flag) { 1311 /* dump the environment */ 1312 fprintf(stderr, "Environment:\n"); 1313 for (i = 0; env[i]; i++) 1314 fprintf(stderr, " %.200s\n", env[i]); 1315 } 1316 return env; 1317 } 1318 1319 /* 1320 * Run $HOME/.ssh/rc, /etc/ssh/sshrc, or xauth (whichever is found 1321 * first in this order). 1322 */ 1323 static void 1324 do_rc_files(Session *s, const char *shell) 1325 { 1326 FILE *f = NULL; 1327 char cmd[1024]; 1328 int do_xauth; 1329 struct stat st; 1330 1331 do_xauth = 1332 s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL; 1333 1334 /* ignore _PATH_SSH_USER_RC for subsystems and admin forced commands */ 1335 if (!s->is_subsystem && options.adm_forced_command == NULL && 1336 !no_user_rc && stat(_PATH_SSH_USER_RC, &st) >= 0) { 1337 snprintf(cmd, sizeof cmd, "%s -c '%s %s'", 1338 shell, _PATH_BSHELL, _PATH_SSH_USER_RC); 1339 if (debug_flag) 1340 fprintf(stderr, "Running %s\n", cmd); 1341 f = popen(cmd, "w"); 1342 if (f) { 1343 if (do_xauth) 1344 fprintf(f, "%s %s\n", s->auth_proto, 1345 s->auth_data); 1346 pclose(f); 1347 } else 1348 fprintf(stderr, "Could not run %s\n", 1349 _PATH_SSH_USER_RC); 1350 } else if (stat(_PATH_SSH_SYSTEM_RC, &st) >= 0) { 1351 if (debug_flag) 1352 fprintf(stderr, "Running %s %s\n", _PATH_BSHELL, 1353 _PATH_SSH_SYSTEM_RC); 1354 f = popen(_PATH_BSHELL " " _PATH_SSH_SYSTEM_RC, "w"); 1355 if (f) { 1356 if (do_xauth) 1357 fprintf(f, "%s %s\n", s->auth_proto, 1358 s->auth_data); 1359 pclose(f); 1360 } else 1361 fprintf(stderr, "Could not run %s\n", 1362 _PATH_SSH_SYSTEM_RC); 1363 } else if (do_xauth && options.xauth_location != NULL) { 1364 /* Add authority data to .Xauthority if appropriate. */ 1365 if (debug_flag) { 1366 fprintf(stderr, 1367 "Running %.500s remove %.100s\n", 1368 options.xauth_location, s->auth_display); 1369 fprintf(stderr, 1370 "%.500s add %.100s %.100s %.100s\n", 1371 options.xauth_location, s->auth_display, 1372 s->auth_proto, s->auth_data); 1373 } 1374 snprintf(cmd, sizeof cmd, "%s -q -", 1375 options.xauth_location); 1376 f = popen(cmd, "w"); 1377 if (f) { 1378 fprintf(f, "remove %s\n", 1379 s->auth_display); 1380 fprintf(f, "add %s %s %s\n", 1381 s->auth_display, s->auth_proto, 1382 s->auth_data); 1383 pclose(f); 1384 } else { 1385 fprintf(stderr, "Could not run %s\n", 1386 cmd); 1387 } 1388 } 1389 } 1390 1391 static void 1392 do_nologin(struct passwd *pw) 1393 { 1394 FILE *f = NULL; 1395 char buf[1024], *nl, *def_nl = _PATH_NOLOGIN; 1396 struct stat sb; 1397 1398 #ifdef HAVE_LOGIN_CAP 1399 if (login_getcapbool(lc, "ignorenologin", 0) && pw->pw_uid) 1400 return; 1401 nl = login_getcapstr(lc, "nologin", def_nl, def_nl); 1402 #else 1403 if (pw->pw_uid == 0) 1404 return; 1405 nl = def_nl; 1406 #endif 1407 if (stat(nl, &sb) == -1) { 1408 if (nl != def_nl) 1409 xfree(nl); 1410 return; 1411 } 1412 1413 /* /etc/nologin exists. Print its contents if we can and exit. */ 1414 logit("User %.100s not allowed because %s exists", pw->pw_name, nl); 1415 if ((f = fopen(nl, "r")) != NULL) { 1416 while (fgets(buf, sizeof(buf), f)) 1417 fputs(buf, stderr); 1418 fclose(f); 1419 } 1420 exit(254); 1421 } 1422 1423 /* 1424 * Chroot into a directory after checking it for safety: all path components 1425 * must be root-owned directories with strict permissions. 1426 */ 1427 static void 1428 safely_chroot(const char *path, uid_t uid) 1429 { 1430 const char *cp; 1431 char component[MAXPATHLEN]; 1432 struct stat st; 1433 1434 if (*path != '/') 1435 fatal("chroot path does not begin at root"); 1436 if (strlen(path) >= sizeof(component)) 1437 fatal("chroot path too long"); 1438 1439 /* 1440 * Descend the path, checking that each component is a 1441 * root-owned directory with strict permissions. 1442 */ 1443 for (cp = path; cp != NULL;) { 1444 if ((cp = strchr(cp, '/')) == NULL) 1445 strlcpy(component, path, sizeof(component)); 1446 else { 1447 cp++; 1448 memcpy(component, path, cp - path); 1449 component[cp - path] = '\0'; 1450 } 1451 1452 debug3("%s: checking '%s'", __func__, component); 1453 1454 if (stat(component, &st) != 0) 1455 fatal("%s: stat(\"%s\"): %s", __func__, 1456 component, strerror(errno)); 1457 if (st.st_uid != 0 || (st.st_mode & 022) != 0) 1458 fatal("bad ownership or modes for chroot " 1459 "directory %s\"%s\"", 1460 cp == NULL ? "" : "component ", component); 1461 if (!S_ISDIR(st.st_mode)) 1462 fatal("chroot path %s\"%s\" is not a directory", 1463 cp == NULL ? "" : "component ", component); 1464 1465 } 1466 1467 if (chdir(path) == -1) 1468 fatal("Unable to chdir to chroot path \"%s\": " 1469 "%s", path, strerror(errno)); 1470 if (chroot(path) == -1) 1471 fatal("chroot(\"%s\"): %s", path, strerror(errno)); 1472 if (chdir("/") == -1) 1473 fatal("%s: chdir(/) after chroot: %s", 1474 __func__, strerror(errno)); 1475 verbose("Changed root directory to \"%s\"", path); 1476 } 1477 1478 /* Set login name, uid, gid, and groups. */ 1479 void 1480 do_setusercontext(struct passwd *pw) 1481 { 1482 char *chroot_path, *tmp; 1483 1484 #ifdef WITH_SELINUX 1485 /* Cache selinux status for later use */ 1486 (void)ssh_selinux_enabled(); 1487 #endif 1488 1489 #ifndef HAVE_CYGWIN 1490 if (getuid() == 0 || geteuid() == 0) 1491 #endif /* HAVE_CYGWIN */ 1492 { 1493 #ifdef HAVE_LOGIN_CAP 1494 # ifdef __bsdi__ 1495 setpgid(0, 0); 1496 # endif 1497 # ifdef USE_PAM 1498 if (options.use_pam) { 1499 do_pam_setcred(use_privsep); 1500 } 1501 # endif /* USE_PAM */ 1502 if (setusercontext(lc, pw, pw->pw_uid, 1503 (LOGIN_SETALL & ~(LOGIN_SETENV|LOGIN_SETPATH|LOGIN_SETUSER))) < 0) { 1504 perror("unable to set user context"); 1505 exit(1); 1506 } 1507 #else 1508 # if defined(HAVE_GETLUID) && defined(HAVE_SETLUID) 1509 /* Sets login uid for accounting */ 1510 if (getluid() == -1 && setluid(pw->pw_uid) == -1) 1511 error("setluid: %s", strerror(errno)); 1512 # endif /* defined(HAVE_GETLUID) && defined(HAVE_SETLUID) */ 1513 1514 if (setlogin(pw->pw_name) < 0) 1515 error("setlogin failed: %s", strerror(errno)); 1516 if (setgid(pw->pw_gid) < 0) { 1517 perror("setgid"); 1518 exit(1); 1519 } 1520 /* Initialize the group list. */ 1521 if (initgroups(pw->pw_name, pw->pw_gid) < 0) { 1522 perror("initgroups"); 1523 exit(1); 1524 } 1525 endgrent(); 1526 # ifdef USE_PAM 1527 /* 1528 * PAM credentials may take the form of supplementary groups. 1529 * These will have been wiped by the above initgroups() call. 1530 * Reestablish them here. 1531 */ 1532 if (options.use_pam) { 1533 do_pam_setcred(use_privsep); 1534 } 1535 # endif /* USE_PAM */ 1536 # if defined(WITH_IRIX_PROJECT) || defined(WITH_IRIX_JOBS) || defined(WITH_IRIX_ARRAY) 1537 irix_setusercontext(pw); 1538 # endif /* defined(WITH_IRIX_PROJECT) || defined(WITH_IRIX_JOBS) || defined(WITH_IRIX_ARRAY) */ 1539 # ifdef _AIX 1540 aix_usrinfo(pw); 1541 # endif /* _AIX */ 1542 # ifdef USE_LIBIAF 1543 if (set_id(pw->pw_name) != 0) { 1544 exit(1); 1545 } 1546 # endif /* USE_LIBIAF */ 1547 #endif 1548 #ifdef HAVE_SETPCRED 1549 /* 1550 * If we have a chroot directory, we set all creds except real 1551 * uid which we will need for chroot. If we don't have a 1552 * chroot directory, we don't override anything. 1553 */ 1554 { 1555 char **creds = NULL, *chroot_creds[] = 1556 { "REAL_USER=root", NULL }; 1557 1558 if (options.chroot_directory != NULL && 1559 strcasecmp(options.chroot_directory, "none") != 0) 1560 creds = chroot_creds; 1561 1562 if (setpcred(pw->pw_name, creds) == -1) 1563 fatal("Failed to set process credentials"); 1564 } 1565 #endif /* HAVE_SETPCRED */ 1566 1567 #ifdef WITH_SELINUX 1568 ssh_selinux_setup_exec_context(pw->pw_name); 1569 #endif 1570 1571 if (options.chroot_directory != NULL && 1572 strcasecmp(options.chroot_directory, "none") != 0) { 1573 tmp = tilde_expand_filename(options.chroot_directory, 1574 pw->pw_uid); 1575 chroot_path = percent_expand(tmp, "h", pw->pw_dir, 1576 "u", pw->pw_name, (char *)NULL); 1577 safely_chroot(chroot_path, pw->pw_uid); 1578 free(tmp); 1579 free(chroot_path); 1580 } 1581 1582 #ifdef HAVE_LOGIN_CAP 1583 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUSER) < 0) { 1584 perror("unable to set user context (setuser)"); 1585 exit(1); 1586 } 1587 #else 1588 /* Permanently switch to the desired uid. */ 1589 permanently_set_uid(pw); 1590 #endif 1591 } 1592 1593 if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) 1594 fatal("Failed to set uids to %u.", (u_int) pw->pw_uid); 1595 } 1596 1597 static void 1598 do_pwchange(Session *s) 1599 { 1600 fflush(NULL); 1601 fprintf(stderr, "WARNING: Your password has expired.\n"); 1602 if (s->ttyfd != -1) { 1603 fprintf(stderr, 1604 "You must change your password now and login again!\n"); 1605 #ifdef PASSWD_NEEDS_USERNAME 1606 execl(_PATH_PASSWD_PROG, "passwd", s->pw->pw_name, 1607 (char *)NULL); 1608 #else 1609 execl(_PATH_PASSWD_PROG, "passwd", (char *)NULL); 1610 #endif 1611 perror("passwd"); 1612 } else { 1613 fprintf(stderr, 1614 "Password change required but no TTY available.\n"); 1615 } 1616 exit(1); 1617 } 1618 1619 static void 1620 launch_login(struct passwd *pw, const char *hostname) 1621 { 1622 /* Launch login(1). */ 1623 1624 execl(LOGIN_PROGRAM, "login", "-h", hostname, 1625 #ifdef xxxLOGIN_NEEDS_TERM 1626 (s->term ? s->term : "unknown"), 1627 #endif /* LOGIN_NEEDS_TERM */ 1628 #ifdef LOGIN_NO_ENDOPT 1629 "-p", "-f", pw->pw_name, (char *)NULL); 1630 #else 1631 "-p", "-f", "--", pw->pw_name, (char *)NULL); 1632 #endif 1633 1634 /* Login couldn't be executed, die. */ 1635 1636 perror("login"); 1637 exit(1); 1638 } 1639 1640 static void 1641 child_close_fds(void) 1642 { 1643 int i; 1644 1645 if (packet_get_connection_in() == packet_get_connection_out()) 1646 close(packet_get_connection_in()); 1647 else { 1648 close(packet_get_connection_in()); 1649 close(packet_get_connection_out()); 1650 } 1651 /* 1652 * Close all descriptors related to channels. They will still remain 1653 * open in the parent. 1654 */ 1655 /* XXX better use close-on-exec? -markus */ 1656 channel_close_all(); 1657 1658 /* 1659 * Close any extra file descriptors. Note that there may still be 1660 * descriptors left by system functions. They will be closed later. 1661 */ 1662 endpwent(); 1663 1664 /* 1665 * Close any extra open file descriptors so that we don't have them 1666 * hanging around in clients. Note that we want to do this after 1667 * initgroups, because at least on Solaris 2.3 it leaves file 1668 * descriptors open. 1669 */ 1670 for (i = 3; i < 64; i++) 1671 close(i); 1672 } 1673 1674 /* 1675 * Performs common processing for the child, such as setting up the 1676 * environment, closing extra file descriptors, setting the user and group 1677 * ids, and executing the command or shell. 1678 */ 1679 #define ARGV_MAX 10 1680 void 1681 do_child(Session *s, const char *command) 1682 { 1683 extern char **environ; 1684 char **env; 1685 char *argv[ARGV_MAX]; 1686 const char *shell, *shell0, *hostname = NULL; 1687 struct passwd *pw = s->pw; 1688 int r = 0; 1689 1690 /* remove hostkey from the child's memory */ 1691 destroy_sensitive_data(); 1692 1693 /* Force a password change */ 1694 if (s->authctxt->force_pwchange) { 1695 do_setusercontext(pw); 1696 child_close_fds(); 1697 do_pwchange(s); 1698 exit(1); 1699 } 1700 1701 /* login(1) is only called if we execute the login shell */ 1702 if (options.use_login && command != NULL) 1703 options.use_login = 0; 1704 1705 #ifdef _UNICOS 1706 cray_setup(pw->pw_uid, pw->pw_name, command); 1707 #endif /* _UNICOS */ 1708 1709 /* 1710 * Login(1) does this as well, and it needs uid 0 for the "-h" 1711 * switch, so we let login(1) to this for us. 1712 */ 1713 if (!options.use_login) { 1714 #ifdef HAVE_OSF_SIA 1715 session_setup_sia(pw, s->ttyfd == -1 ? NULL : s->tty); 1716 if (!check_quietlogin(s, command)) 1717 do_motd(); 1718 #else /* HAVE_OSF_SIA */ 1719 /* When PAM is enabled we rely on it to do the nologin check */ 1720 if (!options.use_pam) 1721 do_nologin(pw); 1722 do_setusercontext(pw); 1723 /* 1724 * PAM session modules in do_setusercontext may have 1725 * generated messages, so if this in an interactive 1726 * login then display them too. 1727 */ 1728 if (!check_quietlogin(s, command)) 1729 display_loginmsg(); 1730 #endif /* HAVE_OSF_SIA */ 1731 } 1732 1733 #ifdef USE_PAM 1734 if (options.use_pam && !options.use_login && !is_pam_session_open()) { 1735 debug3("PAM session not opened, exiting"); 1736 display_loginmsg(); 1737 exit(254); 1738 } 1739 #endif 1740 1741 /* 1742 * Get the shell from the password data. An empty shell field is 1743 * legal, and means /bin/sh. 1744 */ 1745 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; 1746 1747 /* 1748 * Make sure $SHELL points to the shell from the password file, 1749 * even if shell is overridden from login.conf 1750 */ 1751 env = do_setup_env(s, shell); 1752 1753 #ifdef HAVE_LOGIN_CAP 1754 shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell); 1755 #endif 1756 1757 /* we have to stash the hostname before we close our socket. */ 1758 if (options.use_login) 1759 hostname = get_remote_name_or_ip(utmp_len, 1760 options.use_dns); 1761 /* 1762 * Close the connection descriptors; note that this is the child, and 1763 * the server will still have the socket open, and it is important 1764 * that we do not shutdown it. Note that the descriptors cannot be 1765 * closed before building the environment, as we call 1766 * get_remote_ipaddr there. 1767 */ 1768 child_close_fds(); 1769 1770 /* 1771 * Must take new environment into use so that .ssh/rc, 1772 * /etc/ssh/sshrc and xauth are run in the proper environment. 1773 */ 1774 environ = env; 1775 1776 #if defined(KRB5) && defined(USE_AFS) 1777 /* 1778 * At this point, we check to see if AFS is active and if we have 1779 * a valid Kerberos 5 TGT. If so, it seems like a good idea to see 1780 * if we can (and need to) extend the ticket into an AFS token. If 1781 * we don't do this, we run into potential problems if the user's 1782 * home directory is in AFS and it's not world-readable. 1783 */ 1784 1785 if (options.kerberos_get_afs_token && k_hasafs() && 1786 (s->authctxt->krb5_ctx != NULL)) { 1787 char cell[64]; 1788 1789 debug("Getting AFS token"); 1790 1791 k_setpag(); 1792 1793 if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0) 1794 krb5_afslog(s->authctxt->krb5_ctx, 1795 s->authctxt->krb5_fwd_ccache, cell, NULL); 1796 1797 krb5_afslog_home(s->authctxt->krb5_ctx, 1798 s->authctxt->krb5_fwd_ccache, NULL, NULL, pw->pw_dir); 1799 } 1800 #endif 1801 1802 /* Change current directory to the user's home directory. */ 1803 if (chdir(pw->pw_dir) < 0) { 1804 /* Suppress missing homedir warning for chroot case */ 1805 #ifdef HAVE_LOGIN_CAP 1806 r = login_getcapbool(lc, "requirehome", 0); 1807 #endif 1808 if (r || options.chroot_directory == NULL || 1809 strcasecmp(options.chroot_directory, "none") == 0) 1810 fprintf(stderr, "Could not chdir to home " 1811 "directory %s: %s\n", pw->pw_dir, 1812 strerror(errno)); 1813 if (r) 1814 exit(1); 1815 } 1816 1817 closefrom(STDERR_FILENO + 1); 1818 1819 if (!options.use_login) 1820 do_rc_files(s, shell); 1821 1822 /* restore SIGPIPE for child */ 1823 signal(SIGPIPE, SIG_DFL); 1824 1825 if (s->is_subsystem == SUBSYSTEM_INT_SFTP_ERROR) { 1826 printf("This service allows sftp connections only.\n"); 1827 fflush(NULL); 1828 exit(1); 1829 } else if (s->is_subsystem == SUBSYSTEM_INT_SFTP) { 1830 extern int optind, optreset; 1831 int i; 1832 char *p, *args; 1833 1834 setproctitle("%s@%s", s->pw->pw_name, INTERNAL_SFTP_NAME); 1835 args = xstrdup(command ? command : "sftp-server"); 1836 for (i = 0, (p = strtok(args, " ")); p; (p = strtok(NULL, " "))) 1837 if (i < ARGV_MAX - 1) 1838 argv[i++] = p; 1839 argv[i] = NULL; 1840 optind = optreset = 1; 1841 __progname = argv[0]; 1842 #ifdef WITH_SELINUX 1843 ssh_selinux_change_context("sftpd_t"); 1844 #endif 1845 exit(sftp_server_main(i, argv, s->pw)); 1846 } 1847 1848 fflush(NULL); 1849 1850 if (options.use_login) { 1851 launch_login(pw, hostname); 1852 /* NEVERREACHED */ 1853 } 1854 1855 /* Get the last component of the shell name. */ 1856 if ((shell0 = strrchr(shell, '/')) != NULL) 1857 shell0++; 1858 else 1859 shell0 = shell; 1860 1861 /* 1862 * If we have no command, execute the shell. In this case, the shell 1863 * name to be passed in argv[0] is preceded by '-' to indicate that 1864 * this is a login shell. 1865 */ 1866 if (!command) { 1867 char argv0[256]; 1868 1869 /* Start the shell. Set initial character to '-'. */ 1870 argv0[0] = '-'; 1871 1872 if (strlcpy(argv0 + 1, shell0, sizeof(argv0) - 1) 1873 >= sizeof(argv0) - 1) { 1874 errno = EINVAL; 1875 perror(shell); 1876 exit(1); 1877 } 1878 1879 /* Execute the shell. */ 1880 argv[0] = argv0; 1881 argv[1] = NULL; 1882 execve(shell, argv, env); 1883 1884 /* Executing the shell failed. */ 1885 perror(shell); 1886 exit(1); 1887 } 1888 /* 1889 * Execute the command using the user's shell. This uses the -c 1890 * option to execute the command. 1891 */ 1892 argv[0] = (char *) shell0; 1893 argv[1] = "-c"; 1894 argv[2] = (char *) command; 1895 argv[3] = NULL; 1896 execve(shell, argv, env); 1897 perror(shell); 1898 exit(1); 1899 } 1900 1901 void 1902 session_unused(int id) 1903 { 1904 debug3("%s: session id %d unused", __func__, id); 1905 if (id >= options.max_sessions || 1906 id >= sessions_nalloc) { 1907 fatal("%s: insane session id %d (max %d nalloc %d)", 1908 __func__, id, options.max_sessions, sessions_nalloc); 1909 } 1910 bzero(&sessions[id], sizeof(*sessions)); 1911 sessions[id].self = id; 1912 sessions[id].used = 0; 1913 sessions[id].chanid = -1; 1914 sessions[id].ptyfd = -1; 1915 sessions[id].ttyfd = -1; 1916 sessions[id].ptymaster = -1; 1917 sessions[id].x11_chanids = NULL; 1918 sessions[id].next_unused = sessions_first_unused; 1919 sessions_first_unused = id; 1920 } 1921 1922 Session * 1923 session_new(void) 1924 { 1925 Session *s, *tmp; 1926 1927 if (sessions_first_unused == -1) { 1928 if (sessions_nalloc >= options.max_sessions) 1929 return NULL; 1930 debug2("%s: allocate (allocated %d max %d)", 1931 __func__, sessions_nalloc, options.max_sessions); 1932 tmp = xrealloc(sessions, sessions_nalloc + 1, 1933 sizeof(*sessions)); 1934 if (tmp == NULL) { 1935 error("%s: cannot allocate %d sessions", 1936 __func__, sessions_nalloc + 1); 1937 return NULL; 1938 } 1939 sessions = tmp; 1940 session_unused(sessions_nalloc++); 1941 } 1942 1943 if (sessions_first_unused >= sessions_nalloc || 1944 sessions_first_unused < 0) { 1945 fatal("%s: insane first_unused %d max %d nalloc %d", 1946 __func__, sessions_first_unused, options.max_sessions, 1947 sessions_nalloc); 1948 } 1949 1950 s = &sessions[sessions_first_unused]; 1951 if (s->used) { 1952 fatal("%s: session %d already used", 1953 __func__, sessions_first_unused); 1954 } 1955 sessions_first_unused = s->next_unused; 1956 s->used = 1; 1957 s->next_unused = -1; 1958 debug("session_new: session %d", s->self); 1959 1960 return s; 1961 } 1962 1963 static void 1964 session_dump(void) 1965 { 1966 int i; 1967 for (i = 0; i < sessions_nalloc; i++) { 1968 Session *s = &sessions[i]; 1969 1970 debug("dump: used %d next_unused %d session %d %p " 1971 "channel %d pid %ld", 1972 s->used, 1973 s->next_unused, 1974 s->self, 1975 s, 1976 s->chanid, 1977 (long)s->pid); 1978 } 1979 } 1980 1981 int 1982 session_open(Authctxt *authctxt, int chanid) 1983 { 1984 Session *s = session_new(); 1985 debug("session_open: channel %d", chanid); 1986 if (s == NULL) { 1987 error("no more sessions"); 1988 return 0; 1989 } 1990 s->authctxt = authctxt; 1991 s->pw = authctxt->pw; 1992 if (s->pw == NULL || !authctxt->valid) 1993 fatal("no user for session %d", s->self); 1994 debug("session_open: session %d: link with channel %d", s->self, chanid); 1995 s->chanid = chanid; 1996 return 1; 1997 } 1998 1999 Session * 2000 session_by_tty(char *tty) 2001 { 2002 int i; 2003 for (i = 0; i < sessions_nalloc; i++) { 2004 Session *s = &sessions[i]; 2005 if (s->used && s->ttyfd != -1 && strcmp(s->tty, tty) == 0) { 2006 debug("session_by_tty: session %d tty %s", i, tty); 2007 return s; 2008 } 2009 } 2010 debug("session_by_tty: unknown tty %.100s", tty); 2011 session_dump(); 2012 return NULL; 2013 } 2014 2015 static Session * 2016 session_by_channel(int id) 2017 { 2018 int i; 2019 for (i = 0; i < sessions_nalloc; i++) { 2020 Session *s = &sessions[i]; 2021 if (s->used && s->chanid == id) { 2022 debug("session_by_channel: session %d channel %d", 2023 i, id); 2024 return s; 2025 } 2026 } 2027 debug("session_by_channel: unknown channel %d", id); 2028 session_dump(); 2029 return NULL; 2030 } 2031 2032 static Session * 2033 session_by_x11_channel(int id) 2034 { 2035 int i, j; 2036 2037 for (i = 0; i < sessions_nalloc; i++) { 2038 Session *s = &sessions[i]; 2039 2040 if (s->x11_chanids == NULL || !s->used) 2041 continue; 2042 for (j = 0; s->x11_chanids[j] != -1; j++) { 2043 if (s->x11_chanids[j] == id) { 2044 debug("session_by_x11_channel: session %d " 2045 "channel %d", s->self, id); 2046 return s; 2047 } 2048 } 2049 } 2050 debug("session_by_x11_channel: unknown channel %d", id); 2051 session_dump(); 2052 return NULL; 2053 } 2054 2055 static Session * 2056 session_by_pid(pid_t pid) 2057 { 2058 int i; 2059 debug("session_by_pid: pid %ld", (long)pid); 2060 for (i = 0; i < sessions_nalloc; i++) { 2061 Session *s = &sessions[i]; 2062 if (s->used && s->pid == pid) 2063 return s; 2064 } 2065 error("session_by_pid: unknown pid %ld", (long)pid); 2066 session_dump(); 2067 return NULL; 2068 } 2069 2070 static int 2071 session_window_change_req(Session *s) 2072 { 2073 s->col = packet_get_int(); 2074 s->row = packet_get_int(); 2075 s->xpixel = packet_get_int(); 2076 s->ypixel = packet_get_int(); 2077 packet_check_eom(); 2078 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 2079 return 1; 2080 } 2081 2082 static int 2083 session_pty_req(Session *s) 2084 { 2085 u_int len; 2086 int n_bytes; 2087 2088 if (no_pty_flag) { 2089 debug("Allocating a pty not permitted for this authentication."); 2090 return 0; 2091 } 2092 if (s->ttyfd != -1) { 2093 packet_disconnect("Protocol error: you already have a pty."); 2094 return 0; 2095 } 2096 2097 s->term = packet_get_string(&len); 2098 2099 if (compat20) { 2100 s->col = packet_get_int(); 2101 s->row = packet_get_int(); 2102 } else { 2103 s->row = packet_get_int(); 2104 s->col = packet_get_int(); 2105 } 2106 s->xpixel = packet_get_int(); 2107 s->ypixel = packet_get_int(); 2108 2109 if (strcmp(s->term, "") == 0) { 2110 xfree(s->term); 2111 s->term = NULL; 2112 } 2113 2114 /* Allocate a pty and open it. */ 2115 debug("Allocating pty."); 2116 if (!PRIVSEP(pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, 2117 sizeof(s->tty)))) { 2118 if (s->term) 2119 xfree(s->term); 2120 s->term = NULL; 2121 s->ptyfd = -1; 2122 s->ttyfd = -1; 2123 error("session_pty_req: session %d alloc failed", s->self); 2124 return 0; 2125 } 2126 debug("session_pty_req: session %d alloc %s", s->self, s->tty); 2127 2128 /* for SSH1 the tty modes length is not given */ 2129 if (!compat20) 2130 n_bytes = packet_remaining(); 2131 tty_parse_modes(s->ttyfd, &n_bytes); 2132 2133 if (!use_privsep) 2134 pty_setowner(s->pw, s->tty); 2135 2136 /* Set window size from the packet. */ 2137 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 2138 2139 packet_check_eom(); 2140 session_proctitle(s); 2141 return 1; 2142 } 2143 2144 static int 2145 session_subsystem_req(Session *s) 2146 { 2147 struct stat st; 2148 u_int len; 2149 int success = 0; 2150 char *prog, *cmd, *subsys = packet_get_string(&len); 2151 u_int i; 2152 2153 packet_check_eom(); 2154 logit("subsystem request for %.100s by user %s", subsys, 2155 s->pw->pw_name); 2156 2157 for (i = 0; i < options.num_subsystems; i++) { 2158 if (strcmp(subsys, options.subsystem_name[i]) == 0) { 2159 prog = options.subsystem_command[i]; 2160 cmd = options.subsystem_args[i]; 2161 if (strcmp(INTERNAL_SFTP_NAME, prog) == 0) { 2162 s->is_subsystem = SUBSYSTEM_INT_SFTP; 2163 debug("subsystem: %s", prog); 2164 } else { 2165 if (stat(prog, &st) < 0) 2166 debug("subsystem: cannot stat %s: %s", 2167 prog, strerror(errno)); 2168 s->is_subsystem = SUBSYSTEM_EXT; 2169 debug("subsystem: exec() %s", cmd); 2170 } 2171 success = do_exec(s, cmd) == 0; 2172 break; 2173 } 2174 } 2175 2176 if (!success) 2177 logit("subsystem request for %.100s failed, subsystem not found", 2178 subsys); 2179 2180 xfree(subsys); 2181 return success; 2182 } 2183 2184 static int 2185 session_x11_req(Session *s) 2186 { 2187 int success; 2188 2189 if (s->auth_proto != NULL || s->auth_data != NULL) { 2190 error("session_x11_req: session %d: " 2191 "x11 forwarding already active", s->self); 2192 return 0; 2193 } 2194 s->single_connection = packet_get_char(); 2195 s->auth_proto = packet_get_string(NULL); 2196 s->auth_data = packet_get_string(NULL); 2197 s->screen = packet_get_int(); 2198 packet_check_eom(); 2199 2200 success = session_setup_x11fwd(s); 2201 if (!success) { 2202 xfree(s->auth_proto); 2203 xfree(s->auth_data); 2204 s->auth_proto = NULL; 2205 s->auth_data = NULL; 2206 } 2207 return success; 2208 } 2209 2210 static int 2211 session_shell_req(Session *s) 2212 { 2213 packet_check_eom(); 2214 return do_exec(s, NULL) == 0; 2215 } 2216 2217 static int 2218 session_exec_req(Session *s) 2219 { 2220 u_int len, success; 2221 2222 char *command = packet_get_string(&len); 2223 packet_check_eom(); 2224 success = do_exec(s, command) == 0; 2225 xfree(command); 2226 return success; 2227 } 2228 2229 static int 2230 session_break_req(Session *s) 2231 { 2232 2233 packet_get_int(); /* ignored */ 2234 packet_check_eom(); 2235 2236 if (s->ttyfd == -1 || tcsendbreak(s->ttyfd, 0) < 0) 2237 return 0; 2238 return 1; 2239 } 2240 2241 static int 2242 session_env_req(Session *s) 2243 { 2244 char *name, *val; 2245 u_int name_len, val_len, i; 2246 2247 name = packet_get_string(&name_len); 2248 val = packet_get_string(&val_len); 2249 packet_check_eom(); 2250 2251 /* Don't set too many environment variables */ 2252 if (s->num_env > 128) { 2253 debug2("Ignoring env request %s: too many env vars", name); 2254 goto fail; 2255 } 2256 2257 for (i = 0; i < options.num_accept_env; i++) { 2258 if (match_pattern(name, options.accept_env[i])) { 2259 debug2("Setting env %d: %s=%s", s->num_env, name, val); 2260 s->env = xrealloc(s->env, s->num_env + 1, 2261 sizeof(*s->env)); 2262 s->env[s->num_env].name = name; 2263 s->env[s->num_env].val = val; 2264 s->num_env++; 2265 return (1); 2266 } 2267 } 2268 debug2("Ignoring env request %s: disallowed name", name); 2269 2270 fail: 2271 xfree(name); 2272 xfree(val); 2273 return (0); 2274 } 2275 2276 static int 2277 session_auth_agent_req(Session *s) 2278 { 2279 static int called = 0; 2280 packet_check_eom(); 2281 if (no_agent_forwarding_flag || !options.allow_agent_forwarding) { 2282 debug("session_auth_agent_req: no_agent_forwarding_flag"); 2283 return 0; 2284 } 2285 if (called) { 2286 return 0; 2287 } else { 2288 called = 1; 2289 return auth_input_request_forwarding(s->pw); 2290 } 2291 } 2292 2293 int 2294 session_input_channel_req(Channel *c, const char *rtype) 2295 { 2296 int success = 0; 2297 Session *s; 2298 2299 if ((s = session_by_channel(c->self)) == NULL) { 2300 logit("session_input_channel_req: no session %d req %.100s", 2301 c->self, rtype); 2302 return 0; 2303 } 2304 debug("session_input_channel_req: session %d req %s", s->self, rtype); 2305 2306 /* 2307 * a session is in LARVAL state until a shell, a command 2308 * or a subsystem is executed 2309 */ 2310 if (c->type == SSH_CHANNEL_LARVAL) { 2311 if (strcmp(rtype, "shell") == 0) { 2312 success = session_shell_req(s); 2313 } else if (strcmp(rtype, "exec") == 0) { 2314 success = session_exec_req(s); 2315 } else if (strcmp(rtype, "pty-req") == 0) { 2316 success = session_pty_req(s); 2317 } else if (strcmp(rtype, "x11-req") == 0) { 2318 success = session_x11_req(s); 2319 } else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) { 2320 success = session_auth_agent_req(s); 2321 } else if (strcmp(rtype, "subsystem") == 0) { 2322 success = session_subsystem_req(s); 2323 } else if (strcmp(rtype, "env") == 0) { 2324 success = session_env_req(s); 2325 } 2326 } 2327 if (strcmp(rtype, "window-change") == 0) { 2328 success = session_window_change_req(s); 2329 } else if (strcmp(rtype, "break") == 0) { 2330 success = session_break_req(s); 2331 } 2332 2333 return success; 2334 } 2335 2336 void 2337 session_set_fds(Session *s, int fdin, int fdout, int fderr, int ignore_fderr, 2338 int is_tty) 2339 { 2340 if (!compat20) 2341 fatal("session_set_fds: called for proto != 2.0"); 2342 /* 2343 * now that have a child and a pipe to the child, 2344 * we can activate our channel and register the fd's 2345 */ 2346 if (s->chanid == -1) 2347 fatal("no channel for session %d", s->self); 2348 channel_set_fds(s->chanid, 2349 fdout, fdin, fderr, 2350 ignore_fderr ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ, 2351 1, is_tty, CHAN_SES_WINDOW_DEFAULT); 2352 } 2353 2354 /* 2355 * Function to perform pty cleanup. Also called if we get aborted abnormally 2356 * (e.g., due to a dropped connection). 2357 */ 2358 void 2359 session_pty_cleanup2(Session *s) 2360 { 2361 if (s == NULL) { 2362 error("session_pty_cleanup: no session"); 2363 return; 2364 } 2365 if (s->ttyfd == -1) 2366 return; 2367 2368 debug("session_pty_cleanup: session %d release %s", s->self, s->tty); 2369 2370 /* Record that the user has logged out. */ 2371 if (s->pid != 0) 2372 record_logout(s->pid, s->tty, s->pw->pw_name); 2373 2374 /* Release the pseudo-tty. */ 2375 if (getuid() == 0) 2376 pty_release(s->tty); 2377 2378 /* 2379 * Close the server side of the socket pairs. We must do this after 2380 * the pty cleanup, so that another process doesn't get this pty 2381 * while we're still cleaning up. 2382 */ 2383 if (s->ptymaster != -1 && close(s->ptymaster) < 0) 2384 error("close(s->ptymaster/%d): %s", 2385 s->ptymaster, strerror(errno)); 2386 2387 /* unlink pty from session */ 2388 s->ttyfd = -1; 2389 } 2390 2391 void 2392 session_pty_cleanup(Session *s) 2393 { 2394 PRIVSEP(session_pty_cleanup2(s)); 2395 } 2396 2397 static char * 2398 sig2name(int sig) 2399 { 2400 #define SSH_SIG(x) if (sig == SIG ## x) return #x 2401 SSH_SIG(ABRT); 2402 SSH_SIG(ALRM); 2403 SSH_SIG(FPE); 2404 SSH_SIG(HUP); 2405 SSH_SIG(ILL); 2406 SSH_SIG(INT); 2407 SSH_SIG(KILL); 2408 SSH_SIG(PIPE); 2409 SSH_SIG(QUIT); 2410 SSH_SIG(SEGV); 2411 SSH_SIG(TERM); 2412 SSH_SIG(USR1); 2413 SSH_SIG(USR2); 2414 #undef SSH_SIG 2415 return "SIG@openssh.com"; 2416 } 2417 2418 static void 2419 session_close_x11(int id) 2420 { 2421 Channel *c; 2422 2423 if ((c = channel_by_id(id)) == NULL) { 2424 debug("session_close_x11: x11 channel %d missing", id); 2425 } else { 2426 /* Detach X11 listener */ 2427 debug("session_close_x11: detach x11 channel %d", id); 2428 channel_cancel_cleanup(id); 2429 if (c->ostate != CHAN_OUTPUT_CLOSED) 2430 chan_mark_dead(c); 2431 } 2432 } 2433 2434 static void 2435 session_close_single_x11(int id, void *arg) 2436 { 2437 Session *s; 2438 u_int i; 2439 2440 debug3("session_close_single_x11: channel %d", id); 2441 channel_cancel_cleanup(id); 2442 if ((s = session_by_x11_channel(id)) == NULL) 2443 fatal("session_close_single_x11: no x11 channel %d", id); 2444 for (i = 0; s->x11_chanids[i] != -1; i++) { 2445 debug("session_close_single_x11: session %d: " 2446 "closing channel %d", s->self, s->x11_chanids[i]); 2447 /* 2448 * The channel "id" is already closing, but make sure we 2449 * close all of its siblings. 2450 */ 2451 if (s->x11_chanids[i] != id) 2452 session_close_x11(s->x11_chanids[i]); 2453 } 2454 xfree(s->x11_chanids); 2455 s->x11_chanids = NULL; 2456 if (s->display) { 2457 xfree(s->display); 2458 s->display = NULL; 2459 } 2460 if (s->auth_proto) { 2461 xfree(s->auth_proto); 2462 s->auth_proto = NULL; 2463 } 2464 if (s->auth_data) { 2465 xfree(s->auth_data); 2466 s->auth_data = NULL; 2467 } 2468 if (s->auth_display) { 2469 xfree(s->auth_display); 2470 s->auth_display = NULL; 2471 } 2472 } 2473 2474 static void 2475 session_exit_message(Session *s, int status) 2476 { 2477 Channel *c; 2478 2479 if ((c = channel_lookup(s->chanid)) == NULL) 2480 fatal("session_exit_message: session %d: no channel %d", 2481 s->self, s->chanid); 2482 debug("session_exit_message: session %d channel %d pid %ld", 2483 s->self, s->chanid, (long)s->pid); 2484 2485 if (WIFEXITED(status)) { 2486 channel_request_start(s->chanid, "exit-status", 0); 2487 packet_put_int(WEXITSTATUS(status)); 2488 packet_send(); 2489 } else if (WIFSIGNALED(status)) { 2490 channel_request_start(s->chanid, "exit-signal", 0); 2491 packet_put_cstring(sig2name(WTERMSIG(status))); 2492 #ifdef WCOREDUMP 2493 packet_put_char(WCOREDUMP(status)? 1 : 0); 2494 #else /* WCOREDUMP */ 2495 packet_put_char(0); 2496 #endif /* WCOREDUMP */ 2497 packet_put_cstring(""); 2498 packet_put_cstring(""); 2499 packet_send(); 2500 } else { 2501 /* Some weird exit cause. Just exit. */ 2502 packet_disconnect("wait returned status %04x.", status); 2503 } 2504 2505 /* disconnect channel */ 2506 debug("session_exit_message: release channel %d", s->chanid); 2507 2508 /* 2509 * Adjust cleanup callback attachment to send close messages when 2510 * the channel gets EOF. The session will be then be closed 2511 * by session_close_by_channel when the childs close their fds. 2512 */ 2513 channel_register_cleanup(c->self, session_close_by_channel, 1); 2514 2515 /* 2516 * emulate a write failure with 'chan_write_failed', nobody will be 2517 * interested in data we write. 2518 * Note that we must not call 'chan_read_failed', since there could 2519 * be some more data waiting in the pipe. 2520 */ 2521 if (c->ostate != CHAN_OUTPUT_CLOSED) 2522 chan_write_failed(c); 2523 } 2524 2525 void 2526 session_close(Session *s) 2527 { 2528 u_int i; 2529 2530 debug("session_close: session %d pid %ld", s->self, (long)s->pid); 2531 if (s->ttyfd != -1) 2532 session_pty_cleanup(s); 2533 if (s->term) 2534 xfree(s->term); 2535 if (s->display) 2536 xfree(s->display); 2537 if (s->x11_chanids) 2538 xfree(s->x11_chanids); 2539 if (s->auth_display) 2540 xfree(s->auth_display); 2541 if (s->auth_data) 2542 xfree(s->auth_data); 2543 if (s->auth_proto) 2544 xfree(s->auth_proto); 2545 if (s->env != NULL) { 2546 for (i = 0; i < s->num_env; i++) { 2547 xfree(s->env[i].name); 2548 xfree(s->env[i].val); 2549 } 2550 xfree(s->env); 2551 } 2552 session_proctitle(s); 2553 session_unused(s->self); 2554 } 2555 2556 void 2557 session_close_by_pid(pid_t pid, int status) 2558 { 2559 Session *s = session_by_pid(pid); 2560 if (s == NULL) { 2561 debug("session_close_by_pid: no session for pid %ld", 2562 (long)pid); 2563 return; 2564 } 2565 if (s->chanid != -1) 2566 session_exit_message(s, status); 2567 if (s->ttyfd != -1) 2568 session_pty_cleanup(s); 2569 s->pid = 0; 2570 } 2571 2572 /* 2573 * this is called when a channel dies before 2574 * the session 'child' itself dies 2575 */ 2576 void 2577 session_close_by_channel(int id, void *arg) 2578 { 2579 Session *s = session_by_channel(id); 2580 u_int i; 2581 2582 if (s == NULL) { 2583 debug("session_close_by_channel: no session for id %d", id); 2584 return; 2585 } 2586 debug("session_close_by_channel: channel %d child %ld", 2587 id, (long)s->pid); 2588 if (s->pid != 0) { 2589 debug("session_close_by_channel: channel %d: has child", id); 2590 /* 2591 * delay detach of session, but release pty, since 2592 * the fd's to the child are already closed 2593 */ 2594 if (s->ttyfd != -1) 2595 session_pty_cleanup(s); 2596 return; 2597 } 2598 /* detach by removing callback */ 2599 channel_cancel_cleanup(s->chanid); 2600 2601 /* Close any X11 listeners associated with this session */ 2602 if (s->x11_chanids != NULL) { 2603 for (i = 0; s->x11_chanids[i] != -1; i++) { 2604 session_close_x11(s->x11_chanids[i]); 2605 s->x11_chanids[i] = -1; 2606 } 2607 } 2608 2609 s->chanid = -1; 2610 session_close(s); 2611 } 2612 2613 void 2614 session_destroy_all(void (*closefunc)(Session *)) 2615 { 2616 int i; 2617 for (i = 0; i < sessions_nalloc; i++) { 2618 Session *s = &sessions[i]; 2619 if (s->used) { 2620 if (closefunc != NULL) 2621 closefunc(s); 2622 else 2623 session_close(s); 2624 } 2625 } 2626 } 2627 2628 static char * 2629 session_tty_list(void) 2630 { 2631 static char buf[1024]; 2632 int i; 2633 char *cp; 2634 2635 buf[0] = '\0'; 2636 for (i = 0; i < sessions_nalloc; i++) { 2637 Session *s = &sessions[i]; 2638 if (s->used && s->ttyfd != -1) { 2639 2640 if (strncmp(s->tty, "/dev/", 5) != 0) { 2641 cp = strrchr(s->tty, '/'); 2642 cp = (cp == NULL) ? s->tty : cp + 1; 2643 } else 2644 cp = s->tty + 5; 2645 2646 if (buf[0] != '\0') 2647 strlcat(buf, ",", sizeof buf); 2648 strlcat(buf, cp, sizeof buf); 2649 } 2650 } 2651 if (buf[0] == '\0') 2652 strlcpy(buf, "notty", sizeof buf); 2653 return buf; 2654 } 2655 2656 void 2657 session_proctitle(Session *s) 2658 { 2659 if (s->pw == NULL) 2660 error("no user for session %d", s->self); 2661 else 2662 setproctitle("%s@%s", s->pw->pw_name, session_tty_list()); 2663 } 2664 2665 int 2666 session_setup_x11fwd(Session *s) 2667 { 2668 struct stat st; 2669 char display[512], auth_display[512]; 2670 char hostname[MAXHOSTNAMELEN]; 2671 u_int i; 2672 2673 if (no_x11_forwarding_flag) { 2674 packet_send_debug("X11 forwarding disabled in user configuration file."); 2675 return 0; 2676 } 2677 if (!options.x11_forwarding) { 2678 debug("X11 forwarding disabled in server configuration file."); 2679 return 0; 2680 } 2681 if (!options.xauth_location || 2682 (stat(options.xauth_location, &st) == -1)) { 2683 packet_send_debug("No xauth program; cannot forward with spoofing."); 2684 return 0; 2685 } 2686 if (options.use_login) { 2687 packet_send_debug("X11 forwarding disabled; " 2688 "not compatible with UseLogin=yes."); 2689 return 0; 2690 } 2691 if (s->display != NULL) { 2692 debug("X11 display already set."); 2693 return 0; 2694 } 2695 if (x11_create_display_inet(options.x11_display_offset, 2696 options.x11_use_localhost, s->single_connection, 2697 &s->display_number, &s->x11_chanids) == -1) { 2698 debug("x11_create_display_inet failed."); 2699 return 0; 2700 } 2701 for (i = 0; s->x11_chanids[i] != -1; i++) { 2702 channel_register_cleanup(s->x11_chanids[i], 2703 session_close_single_x11, 0); 2704 } 2705 2706 /* Set up a suitable value for the DISPLAY variable. */ 2707 if (gethostname(hostname, sizeof(hostname)) < 0) 2708 fatal("gethostname: %.100s", strerror(errno)); 2709 /* 2710 * auth_display must be used as the displayname when the 2711 * authorization entry is added with xauth(1). This will be 2712 * different than the DISPLAY string for localhost displays. 2713 */ 2714 if (options.x11_use_localhost) { 2715 snprintf(display, sizeof display, "localhost:%u.%u", 2716 s->display_number, s->screen); 2717 snprintf(auth_display, sizeof auth_display, "unix:%u.%u", 2718 s->display_number, s->screen); 2719 s->display = xstrdup(display); 2720 s->auth_display = xstrdup(auth_display); 2721 } else { 2722 #ifdef IPADDR_IN_DISPLAY 2723 struct hostent *he; 2724 struct in_addr my_addr; 2725 2726 he = gethostbyname(hostname); 2727 if (he == NULL) { 2728 error("Can't get IP address for X11 DISPLAY."); 2729 packet_send_debug("Can't get IP address for X11 DISPLAY."); 2730 return 0; 2731 } 2732 memcpy(&my_addr, he->h_addr_list[0], sizeof(struct in_addr)); 2733 snprintf(display, sizeof display, "%.50s:%u.%u", inet_ntoa(my_addr), 2734 s->display_number, s->screen); 2735 #else 2736 snprintf(display, sizeof display, "%.400s:%u.%u", hostname, 2737 s->display_number, s->screen); 2738 #endif 2739 s->display = xstrdup(display); 2740 s->auth_display = xstrdup(display); 2741 } 2742 2743 return 1; 2744 } 2745 2746 static void 2747 do_authenticated2(Authctxt *authctxt) 2748 { 2749 server_loop2(authctxt); 2750 } 2751 2752 void 2753 do_cleanup(Authctxt *authctxt) 2754 { 2755 static int called = 0; 2756 2757 debug("do_cleanup"); 2758 2759 /* no cleanup if we're in the child for login shell */ 2760 if (is_child) 2761 return; 2762 2763 /* avoid double cleanup */ 2764 if (called) 2765 return; 2766 called = 1; 2767 2768 if (authctxt == NULL) 2769 return; 2770 2771 #ifdef USE_PAM 2772 if (options.use_pam) { 2773 sshpam_cleanup(); 2774 sshpam_thread_cleanup(); 2775 } 2776 #endif 2777 2778 if (!authctxt->authenticated) 2779 return; 2780 2781 #ifdef KRB5 2782 if (options.kerberos_ticket_cleanup && 2783 authctxt->krb5_ctx) 2784 krb5_cleanup_proc(authctxt); 2785 #endif 2786 2787 #ifdef GSSAPI 2788 if (compat20 && options.gss_cleanup_creds) 2789 ssh_gssapi_cleanup_creds(); 2790 #endif 2791 2792 /* remove agent socket */ 2793 auth_sock_cleanup_proc(authctxt->pw); 2794 2795 /* 2796 * Cleanup ptys/utmp only if privsep is disabled, 2797 * or if running in monitor. 2798 */ 2799 if (!use_privsep || mm_is_monitor()) 2800 session_destroy_all(session_pty_cleanup2); 2801 } 2802