1 /* $OpenBSD: session.c,v 1.266 2013/07/19 07:37:48 markus Exp $ */ 2 /* $FreeBSD$ */ 3 /* 4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 5 * All rights reserved 6 * 7 * As far as I am concerned, the code I have written for this software 8 * can be used freely for any purpose. Any derived versions of this 9 * software must be clearly marked as such, and if the derived work is 10 * incompatible with the protocol description in the RFC file, it must be 11 * called by a name other than "ssh" or "Secure Shell". 12 * 13 * SSH2 support by Markus Friedl. 14 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 15 * 16 * Redistribution and use in source and binary forms, with or without 17 * modification, are permitted provided that the following conditions 18 * are met: 19 * 1. Redistributions of source code must retain the above copyright 20 * notice, this list of conditions and the following disclaimer. 21 * 2. Redistributions in binary form must reproduce the above copyright 22 * notice, this list of conditions and the following disclaimer in the 23 * documentation and/or other materials provided with the distribution. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 26 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 27 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 28 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 29 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 30 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 31 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 32 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 33 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 34 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 35 */ 36 37 #include "includes.h" 38 __RCSID("$FreeBSD$"); 39 40 #include <sys/types.h> 41 #include <sys/param.h> 42 #ifdef HAVE_SYS_STAT_H 43 # include <sys/stat.h> 44 #endif 45 #include <sys/socket.h> 46 #include <sys/un.h> 47 #include <sys/wait.h> 48 49 #include <arpa/inet.h> 50 51 #include <errno.h> 52 #include <fcntl.h> 53 #include <grp.h> 54 #ifdef HAVE_PATHS_H 55 #include <paths.h> 56 #endif 57 #include <pwd.h> 58 #include <signal.h> 59 #include <stdarg.h> 60 #include <stdio.h> 61 #include <stdlib.h> 62 #include <string.h> 63 #include <unistd.h> 64 65 #include "openbsd-compat/sys-queue.h" 66 #include "xmalloc.h" 67 #include "ssh.h" 68 #include "ssh1.h" 69 #include "ssh2.h" 70 #include "sshpty.h" 71 #include "packet.h" 72 #include "buffer.h" 73 #include "match.h" 74 #include "uidswap.h" 75 #include "compat.h" 76 #include "channels.h" 77 #include "key.h" 78 #include "cipher.h" 79 #ifdef GSSAPI 80 #include "ssh-gss.h" 81 #endif 82 #include "hostfile.h" 83 #include "auth.h" 84 #include "auth-options.h" 85 #include "authfd.h" 86 #include "pathnames.h" 87 #include "log.h" 88 #include "servconf.h" 89 #include "sshlogin.h" 90 #include "serverloop.h" 91 #include "canohost.h" 92 #include "misc.h" 93 #include "session.h" 94 #include "kex.h" 95 #include "monitor_wrap.h" 96 #include "sftp.h" 97 98 #if defined(KRB5) && defined(USE_AFS) 99 #include <kafs.h> 100 #endif 101 102 #ifdef WITH_SELINUX 103 #include <selinux/selinux.h> 104 #endif 105 106 #define IS_INTERNAL_SFTP(c) \ 107 (!strncmp(c, INTERNAL_SFTP_NAME, sizeof(INTERNAL_SFTP_NAME) - 1) && \ 108 (c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\0' || \ 109 c[sizeof(INTERNAL_SFTP_NAME) - 1] == ' ' || \ 110 c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\t')) 111 112 /* func */ 113 114 Session *session_new(void); 115 void session_set_fds(Session *, int, int, int, int, int); 116 void session_pty_cleanup(Session *); 117 void session_proctitle(Session *); 118 int session_setup_x11fwd(Session *); 119 int do_exec_pty(Session *, const char *); 120 int do_exec_no_pty(Session *, const char *); 121 int do_exec(Session *, const char *); 122 void do_login(Session *, const char *); 123 #ifdef LOGIN_NEEDS_UTMPX 124 static void do_pre_login(Session *s); 125 #endif 126 void do_child(Session *, const char *); 127 void do_motd(void); 128 int check_quietlogin(Session *, const char *); 129 130 static void do_authenticated1(Authctxt *); 131 static void do_authenticated2(Authctxt *); 132 133 static int session_pty_req(Session *); 134 135 /* import */ 136 extern ServerOptions options; 137 extern char *__progname; 138 extern int log_stderr; 139 extern int debug_flag; 140 extern u_int utmp_len; 141 extern int startup_pipe; 142 extern void destroy_sensitive_data(void); 143 extern Buffer loginmsg; 144 145 /* original command from peer. */ 146 const char *original_command = NULL; 147 148 /* data */ 149 static int sessions_first_unused = -1; 150 static int sessions_nalloc = 0; 151 static Session *sessions = NULL; 152 153 #define SUBSYSTEM_NONE 0 154 #define SUBSYSTEM_EXT 1 155 #define SUBSYSTEM_INT_SFTP 2 156 #define SUBSYSTEM_INT_SFTP_ERROR 3 157 158 #ifdef HAVE_LOGIN_CAP 159 login_cap_t *lc; 160 #endif 161 162 static int is_child = 0; 163 164 /* Name and directory of socket for authentication agent forwarding. */ 165 static char *auth_sock_name = NULL; 166 static char *auth_sock_dir = NULL; 167 168 /* removes the agent forwarding socket */ 169 170 static void 171 auth_sock_cleanup_proc(struct passwd *pw) 172 { 173 if (auth_sock_name != NULL) { 174 temporarily_use_uid(pw); 175 unlink(auth_sock_name); 176 rmdir(auth_sock_dir); 177 auth_sock_name = NULL; 178 restore_uid(); 179 } 180 } 181 182 static int 183 auth_input_request_forwarding(struct passwd * pw) 184 { 185 Channel *nc; 186 int sock = -1; 187 struct sockaddr_un sunaddr; 188 189 if (auth_sock_name != NULL) { 190 error("authentication forwarding requested twice."); 191 return 0; 192 } 193 194 /* Temporarily drop privileged uid for mkdir/bind. */ 195 temporarily_use_uid(pw); 196 197 /* Allocate a buffer for the socket name, and format the name. */ 198 auth_sock_dir = xstrdup("/tmp/ssh-XXXXXXXXXX"); 199 200 /* Create private directory for socket */ 201 if (mkdtemp(auth_sock_dir) == NULL) { 202 packet_send_debug("Agent forwarding disabled: " 203 "mkdtemp() failed: %.100s", strerror(errno)); 204 restore_uid(); 205 free(auth_sock_dir); 206 auth_sock_dir = NULL; 207 goto authsock_err; 208 } 209 210 xasprintf(&auth_sock_name, "%s/agent.%ld", 211 auth_sock_dir, (long) getpid()); 212 213 /* Create the socket. */ 214 sock = socket(AF_UNIX, SOCK_STREAM, 0); 215 if (sock < 0) { 216 error("socket: %.100s", strerror(errno)); 217 restore_uid(); 218 goto authsock_err; 219 } 220 221 /* Bind it to the name. */ 222 memset(&sunaddr, 0, sizeof(sunaddr)); 223 sunaddr.sun_family = AF_UNIX; 224 strlcpy(sunaddr.sun_path, auth_sock_name, sizeof(sunaddr.sun_path)); 225 226 if (bind(sock, (struct sockaddr *)&sunaddr, sizeof(sunaddr)) < 0) { 227 error("bind: %.100s", strerror(errno)); 228 restore_uid(); 229 goto authsock_err; 230 } 231 232 /* Restore the privileged uid. */ 233 restore_uid(); 234 235 /* Start listening on the socket. */ 236 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) { 237 error("listen: %.100s", strerror(errno)); 238 goto authsock_err; 239 } 240 241 /* 242 * Allocate a channel for the authentication agent socket. 243 * Ignore HPN on that one given no improvement expected. 244 */ 245 nc = channel_new("auth socket", 246 SSH_CHANNEL_AUTH_SOCKET, sock, sock, -1, 247 CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 248 0, "auth socket", 1); 249 nc->path = xstrdup(auth_sock_name); 250 return 1; 251 252 authsock_err: 253 free(auth_sock_name); 254 if (auth_sock_dir != NULL) { 255 rmdir(auth_sock_dir); 256 free(auth_sock_dir); 257 } 258 if (sock != -1) 259 close(sock); 260 auth_sock_name = NULL; 261 auth_sock_dir = NULL; 262 return 0; 263 } 264 265 static void 266 display_loginmsg(void) 267 { 268 if (buffer_len(&loginmsg) > 0) { 269 buffer_append(&loginmsg, "\0", 1); 270 printf("%s", (char *)buffer_ptr(&loginmsg)); 271 buffer_clear(&loginmsg); 272 } 273 } 274 275 void 276 do_authenticated(Authctxt *authctxt) 277 { 278 setproctitle("%s", authctxt->pw->pw_name); 279 280 /* setup the channel layer */ 281 if (no_port_forwarding_flag || 282 (options.allow_tcp_forwarding & FORWARD_LOCAL) == 0) 283 channel_disable_adm_local_opens(); 284 else 285 channel_permit_all_opens(); 286 287 auth_debug_send(); 288 289 if (compat20) 290 do_authenticated2(authctxt); 291 else 292 do_authenticated1(authctxt); 293 294 do_cleanup(authctxt); 295 } 296 297 /* 298 * Prepares for an interactive session. This is called after the user has 299 * been successfully authenticated. During this message exchange, pseudo 300 * terminals are allocated, X11, TCP/IP, and authentication agent forwardings 301 * are requested, etc. 302 */ 303 static void 304 do_authenticated1(Authctxt *authctxt) 305 { 306 Session *s; 307 char *command; 308 int success, type, screen_flag; 309 int enable_compression_after_reply = 0; 310 u_int proto_len, data_len, dlen, compression_level = 0; 311 312 s = session_new(); 313 if (s == NULL) { 314 error("no more sessions"); 315 return; 316 } 317 s->authctxt = authctxt; 318 s->pw = authctxt->pw; 319 320 /* 321 * We stay in this loop until the client requests to execute a shell 322 * or a command. 323 */ 324 for (;;) { 325 success = 0; 326 327 /* Get a packet from the client. */ 328 type = packet_read(); 329 330 /* Process the packet. */ 331 switch (type) { 332 case SSH_CMSG_REQUEST_COMPRESSION: 333 compression_level = packet_get_int(); 334 packet_check_eom(); 335 if (compression_level < 1 || compression_level > 9) { 336 packet_send_debug("Received invalid compression level %d.", 337 compression_level); 338 break; 339 } 340 if (options.compression == COMP_NONE) { 341 debug2("compression disabled"); 342 break; 343 } 344 /* Enable compression after we have responded with SUCCESS. */ 345 enable_compression_after_reply = 1; 346 success = 1; 347 break; 348 349 case SSH_CMSG_REQUEST_PTY: 350 success = session_pty_req(s); 351 break; 352 353 case SSH_CMSG_X11_REQUEST_FORWARDING: 354 s->auth_proto = packet_get_string(&proto_len); 355 s->auth_data = packet_get_string(&data_len); 356 357 screen_flag = packet_get_protocol_flags() & 358 SSH_PROTOFLAG_SCREEN_NUMBER; 359 debug2("SSH_PROTOFLAG_SCREEN_NUMBER: %d", screen_flag); 360 361 if (packet_remaining() == 4) { 362 if (!screen_flag) 363 debug2("Buggy client: " 364 "X11 screen flag missing"); 365 s->screen = packet_get_int(); 366 } else { 367 s->screen = 0; 368 } 369 packet_check_eom(); 370 success = session_setup_x11fwd(s); 371 if (!success) { 372 free(s->auth_proto); 373 free(s->auth_data); 374 s->auth_proto = NULL; 375 s->auth_data = NULL; 376 } 377 break; 378 379 case SSH_CMSG_AGENT_REQUEST_FORWARDING: 380 if (!options.allow_agent_forwarding || 381 no_agent_forwarding_flag || compat13) { 382 debug("Authentication agent forwarding not permitted for this authentication."); 383 break; 384 } 385 debug("Received authentication agent forwarding request."); 386 success = auth_input_request_forwarding(s->pw); 387 break; 388 389 case SSH_CMSG_PORT_FORWARD_REQUEST: 390 if (no_port_forwarding_flag) { 391 debug("Port forwarding not permitted for this authentication."); 392 break; 393 } 394 if (!(options.allow_tcp_forwarding & FORWARD_REMOTE)) { 395 debug("Port forwarding not permitted."); 396 break; 397 } 398 debug("Received TCP/IP port forwarding request."); 399 if (channel_input_port_forward_request(s->pw->pw_uid == 0, 400 options.gateway_ports) < 0) { 401 debug("Port forwarding failed."); 402 break; 403 } 404 success = 1; 405 break; 406 407 case SSH_CMSG_MAX_PACKET_SIZE: 408 if (packet_set_maxsize(packet_get_int()) > 0) 409 success = 1; 410 break; 411 412 case SSH_CMSG_EXEC_SHELL: 413 case SSH_CMSG_EXEC_CMD: 414 if (type == SSH_CMSG_EXEC_CMD) { 415 command = packet_get_string(&dlen); 416 debug("Exec command '%.500s'", command); 417 if (do_exec(s, command) != 0) 418 packet_disconnect( 419 "command execution failed"); 420 free(command); 421 } else { 422 if (do_exec(s, NULL) != 0) 423 packet_disconnect( 424 "shell execution failed"); 425 } 426 packet_check_eom(); 427 session_close(s); 428 return; 429 430 default: 431 /* 432 * Any unknown messages in this phase are ignored, 433 * and a failure message is returned. 434 */ 435 logit("Unknown packet type received after authentication: %d", type); 436 } 437 packet_start(success ? SSH_SMSG_SUCCESS : SSH_SMSG_FAILURE); 438 packet_send(); 439 packet_write_wait(); 440 441 /* Enable compression now that we have replied if appropriate. */ 442 if (enable_compression_after_reply) { 443 enable_compression_after_reply = 0; 444 packet_start_compression(compression_level); 445 } 446 } 447 } 448 449 #define USE_PIPES 450 /* 451 * This is called to fork and execute a command when we have no tty. This 452 * will call do_child from the child, and server_loop from the parent after 453 * setting up file descriptors and such. 454 */ 455 int 456 do_exec_no_pty(Session *s, const char *command) 457 { 458 pid_t pid; 459 460 #ifdef USE_PIPES 461 int pin[2], pout[2], perr[2]; 462 463 if (s == NULL) 464 fatal("do_exec_no_pty: no session"); 465 466 /* Allocate pipes for communicating with the program. */ 467 if (pipe(pin) < 0) { 468 error("%s: pipe in: %.100s", __func__, strerror(errno)); 469 return -1; 470 } 471 if (pipe(pout) < 0) { 472 error("%s: pipe out: %.100s", __func__, strerror(errno)); 473 close(pin[0]); 474 close(pin[1]); 475 return -1; 476 } 477 if (pipe(perr) < 0) { 478 error("%s: pipe err: %.100s", __func__, 479 strerror(errno)); 480 close(pin[0]); 481 close(pin[1]); 482 close(pout[0]); 483 close(pout[1]); 484 return -1; 485 } 486 #else 487 int inout[2], err[2]; 488 489 if (s == NULL) 490 fatal("do_exec_no_pty: no session"); 491 492 /* Uses socket pairs to communicate with the program. */ 493 if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) < 0) { 494 error("%s: socketpair #1: %.100s", __func__, strerror(errno)); 495 return -1; 496 } 497 if (socketpair(AF_UNIX, SOCK_STREAM, 0, err) < 0) { 498 error("%s: socketpair #2: %.100s", __func__, 499 strerror(errno)); 500 close(inout[0]); 501 close(inout[1]); 502 return -1; 503 } 504 #endif 505 506 session_proctitle(s); 507 508 /* Fork the child. */ 509 switch ((pid = fork())) { 510 case -1: 511 error("%s: fork: %.100s", __func__, strerror(errno)); 512 #ifdef USE_PIPES 513 close(pin[0]); 514 close(pin[1]); 515 close(pout[0]); 516 close(pout[1]); 517 close(perr[0]); 518 close(perr[1]); 519 #else 520 close(inout[0]); 521 close(inout[1]); 522 close(err[0]); 523 close(err[1]); 524 #endif 525 return -1; 526 case 0: 527 is_child = 1; 528 529 /* Child. Reinitialize the log since the pid has changed. */ 530 log_init(__progname, options.log_level, 531 options.log_facility, log_stderr); 532 533 /* 534 * Create a new session and process group since the 4.4BSD 535 * setlogin() affects the entire process group. 536 */ 537 if (setsid() < 0) 538 error("setsid failed: %.100s", strerror(errno)); 539 540 #ifdef USE_PIPES 541 /* 542 * Redirect stdin. We close the parent side of the socket 543 * pair, and make the child side the standard input. 544 */ 545 close(pin[1]); 546 if (dup2(pin[0], 0) < 0) 547 perror("dup2 stdin"); 548 close(pin[0]); 549 550 /* Redirect stdout. */ 551 close(pout[0]); 552 if (dup2(pout[1], 1) < 0) 553 perror("dup2 stdout"); 554 close(pout[1]); 555 556 /* Redirect stderr. */ 557 close(perr[0]); 558 if (dup2(perr[1], 2) < 0) 559 perror("dup2 stderr"); 560 close(perr[1]); 561 #else 562 /* 563 * Redirect stdin, stdout, and stderr. Stdin and stdout will 564 * use the same socket, as some programs (particularly rdist) 565 * seem to depend on it. 566 */ 567 close(inout[1]); 568 close(err[1]); 569 if (dup2(inout[0], 0) < 0) /* stdin */ 570 perror("dup2 stdin"); 571 if (dup2(inout[0], 1) < 0) /* stdout (same as stdin) */ 572 perror("dup2 stdout"); 573 close(inout[0]); 574 if (dup2(err[0], 2) < 0) /* stderr */ 575 perror("dup2 stderr"); 576 close(err[0]); 577 #endif 578 579 580 #ifdef _UNICOS 581 cray_init_job(s->pw); /* set up cray jid and tmpdir */ 582 #endif 583 584 /* Do processing for the child (exec command etc). */ 585 do_child(s, command); 586 /* NOTREACHED */ 587 default: 588 break; 589 } 590 591 #ifdef _UNICOS 592 signal(WJSIGNAL, cray_job_termination_handler); 593 #endif /* _UNICOS */ 594 #ifdef HAVE_CYGWIN 595 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); 596 #endif 597 598 s->pid = pid; 599 /* Set interactive/non-interactive mode. */ 600 packet_set_interactive(s->display != NULL, 601 options.ip_qos_interactive, options.ip_qos_bulk); 602 603 /* 604 * Clear loginmsg, since it's the child's responsibility to display 605 * it to the user, otherwise multiple sessions may accumulate 606 * multiple copies of the login messages. 607 */ 608 buffer_clear(&loginmsg); 609 610 #ifdef USE_PIPES 611 /* We are the parent. Close the child sides of the pipes. */ 612 close(pin[0]); 613 close(pout[1]); 614 close(perr[1]); 615 616 if (compat20) { 617 session_set_fds(s, pin[1], pout[0], perr[0], 618 s->is_subsystem, 0); 619 } else { 620 /* Enter the interactive session. */ 621 server_loop(pid, pin[1], pout[0], perr[0]); 622 /* server_loop has closed pin[1], pout[0], and perr[0]. */ 623 } 624 #else 625 /* We are the parent. Close the child sides of the socket pairs. */ 626 close(inout[0]); 627 close(err[0]); 628 629 /* 630 * Enter the interactive session. Note: server_loop must be able to 631 * handle the case that fdin and fdout are the same. 632 */ 633 if (compat20) { 634 session_set_fds(s, inout[1], inout[1], err[1], 635 s->is_subsystem, 0); 636 } else { 637 server_loop(pid, inout[1], inout[1], err[1]); 638 /* server_loop has closed inout[1] and err[1]. */ 639 } 640 #endif 641 return 0; 642 } 643 644 /* 645 * This is called to fork and execute a command when we have a tty. This 646 * will call do_child from the child, and server_loop from the parent after 647 * setting up file descriptors, controlling tty, updating wtmp, utmp, 648 * lastlog, and other such operations. 649 */ 650 int 651 do_exec_pty(Session *s, const char *command) 652 { 653 int fdout, ptyfd, ttyfd, ptymaster; 654 pid_t pid; 655 656 if (s == NULL) 657 fatal("do_exec_pty: no session"); 658 ptyfd = s->ptyfd; 659 ttyfd = s->ttyfd; 660 661 /* 662 * Create another descriptor of the pty master side for use as the 663 * standard input. We could use the original descriptor, but this 664 * simplifies code in server_loop. The descriptor is bidirectional. 665 * Do this before forking (and cleanup in the child) so as to 666 * detect and gracefully fail out-of-fd conditions. 667 */ 668 if ((fdout = dup(ptyfd)) < 0) { 669 error("%s: dup #1: %s", __func__, strerror(errno)); 670 close(ttyfd); 671 close(ptyfd); 672 return -1; 673 } 674 /* we keep a reference to the pty master */ 675 if ((ptymaster = dup(ptyfd)) < 0) { 676 error("%s: dup #2: %s", __func__, strerror(errno)); 677 close(ttyfd); 678 close(ptyfd); 679 close(fdout); 680 return -1; 681 } 682 683 /* Fork the child. */ 684 switch ((pid = fork())) { 685 case -1: 686 error("%s: fork: %.100s", __func__, strerror(errno)); 687 close(fdout); 688 close(ptymaster); 689 close(ttyfd); 690 close(ptyfd); 691 return -1; 692 case 0: 693 is_child = 1; 694 695 close(fdout); 696 close(ptymaster); 697 698 /* Child. Reinitialize the log because the pid has changed. */ 699 log_init(__progname, options.log_level, 700 options.log_facility, log_stderr); 701 /* Close the master side of the pseudo tty. */ 702 close(ptyfd); 703 704 /* Make the pseudo tty our controlling tty. */ 705 pty_make_controlling_tty(&ttyfd, s->tty); 706 707 /* Redirect stdin/stdout/stderr from the pseudo tty. */ 708 if (dup2(ttyfd, 0) < 0) 709 error("dup2 stdin: %s", strerror(errno)); 710 if (dup2(ttyfd, 1) < 0) 711 error("dup2 stdout: %s", strerror(errno)); 712 if (dup2(ttyfd, 2) < 0) 713 error("dup2 stderr: %s", strerror(errno)); 714 715 /* Close the extra descriptor for the pseudo tty. */ 716 close(ttyfd); 717 718 /* record login, etc. similar to login(1) */ 719 #ifndef HAVE_OSF_SIA 720 if (!(options.use_login && command == NULL)) { 721 #ifdef _UNICOS 722 cray_init_job(s->pw); /* set up cray jid and tmpdir */ 723 #endif /* _UNICOS */ 724 do_login(s, command); 725 } 726 # ifdef LOGIN_NEEDS_UTMPX 727 else 728 do_pre_login(s); 729 # endif 730 #endif 731 /* 732 * Do common processing for the child, such as execing 733 * the command. 734 */ 735 do_child(s, command); 736 /* NOTREACHED */ 737 default: 738 break; 739 } 740 741 #ifdef _UNICOS 742 signal(WJSIGNAL, cray_job_termination_handler); 743 #endif /* _UNICOS */ 744 #ifdef HAVE_CYGWIN 745 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); 746 #endif 747 748 s->pid = pid; 749 750 /* Parent. Close the slave side of the pseudo tty. */ 751 close(ttyfd); 752 753 /* Enter interactive session. */ 754 s->ptymaster = ptymaster; 755 packet_set_interactive(1, 756 options.ip_qos_interactive, options.ip_qos_bulk); 757 if (compat20) { 758 session_set_fds(s, ptyfd, fdout, -1, 1, 1); 759 } else { 760 server_loop(pid, ptyfd, fdout, -1); 761 /* server_loop _has_ closed ptyfd and fdout. */ 762 } 763 return 0; 764 } 765 766 #ifdef LOGIN_NEEDS_UTMPX 767 static void 768 do_pre_login(Session *s) 769 { 770 socklen_t fromlen; 771 struct sockaddr_storage from; 772 pid_t pid = getpid(); 773 774 /* 775 * Get IP address of client. If the connection is not a socket, let 776 * the address be 0.0.0.0. 777 */ 778 memset(&from, 0, sizeof(from)); 779 fromlen = sizeof(from); 780 if (packet_connection_is_on_socket()) { 781 if (getpeername(packet_get_connection_in(), 782 (struct sockaddr *)&from, &fromlen) < 0) { 783 debug("getpeername: %.100s", strerror(errno)); 784 cleanup_exit(255); 785 } 786 } 787 788 record_utmp_only(pid, s->tty, s->pw->pw_name, 789 get_remote_name_or_ip(utmp_len, options.use_dns), 790 (struct sockaddr *)&from, fromlen); 791 } 792 #endif 793 794 /* 795 * This is called to fork and execute a command. If another command is 796 * to be forced, execute that instead. 797 */ 798 int 799 do_exec(Session *s, const char *command) 800 { 801 int ret; 802 803 if (options.adm_forced_command) { 804 original_command = command; 805 command = options.adm_forced_command; 806 if (IS_INTERNAL_SFTP(command)) { 807 s->is_subsystem = s->is_subsystem ? 808 SUBSYSTEM_INT_SFTP : SUBSYSTEM_INT_SFTP_ERROR; 809 } else if (s->is_subsystem) 810 s->is_subsystem = SUBSYSTEM_EXT; 811 debug("Forced command (config) '%.900s'", command); 812 } else if (forced_command) { 813 original_command = command; 814 command = forced_command; 815 if (IS_INTERNAL_SFTP(command)) { 816 s->is_subsystem = s->is_subsystem ? 817 SUBSYSTEM_INT_SFTP : SUBSYSTEM_INT_SFTP_ERROR; 818 } else if (s->is_subsystem) 819 s->is_subsystem = SUBSYSTEM_EXT; 820 debug("Forced command (key option) '%.900s'", command); 821 } 822 823 #ifdef SSH_AUDIT_EVENTS 824 if (command != NULL) 825 PRIVSEP(audit_run_command(command)); 826 else if (s->ttyfd == -1) { 827 char *shell = s->pw->pw_shell; 828 829 if (shell[0] == '\0') /* empty shell means /bin/sh */ 830 shell =_PATH_BSHELL; 831 PRIVSEP(audit_run_command(shell)); 832 } 833 #endif 834 if (s->ttyfd != -1) 835 ret = do_exec_pty(s, command); 836 else 837 ret = do_exec_no_pty(s, command); 838 839 original_command = NULL; 840 841 /* 842 * Clear loginmsg: it's the child's responsibility to display 843 * it to the user, otherwise multiple sessions may accumulate 844 * multiple copies of the login messages. 845 */ 846 buffer_clear(&loginmsg); 847 848 return ret; 849 } 850 851 /* administrative, login(1)-like work */ 852 void 853 do_login(Session *s, const char *command) 854 { 855 socklen_t fromlen; 856 struct sockaddr_storage from; 857 struct passwd * pw = s->pw; 858 pid_t pid = getpid(); 859 860 /* 861 * Get IP address of client. If the connection is not a socket, let 862 * the address be 0.0.0.0. 863 */ 864 memset(&from, 0, sizeof(from)); 865 fromlen = sizeof(from); 866 if (packet_connection_is_on_socket()) { 867 if (getpeername(packet_get_connection_in(), 868 (struct sockaddr *)&from, &fromlen) < 0) { 869 debug("getpeername: %.100s", strerror(errno)); 870 cleanup_exit(255); 871 } 872 } 873 874 /* Record that there was a login on that tty from the remote host. */ 875 if (!use_privsep) 876 record_login(pid, s->tty, pw->pw_name, pw->pw_uid, 877 get_remote_name_or_ip(utmp_len, 878 options.use_dns), 879 (struct sockaddr *)&from, fromlen); 880 881 #ifdef USE_PAM 882 /* 883 * If password change is needed, do it now. 884 * This needs to occur before the ~/.hushlogin check. 885 */ 886 if (options.use_pam && !use_privsep && s->authctxt->force_pwchange) { 887 display_loginmsg(); 888 do_pam_chauthtok(); 889 s->authctxt->force_pwchange = 0; 890 /* XXX - signal [net] parent to enable forwardings */ 891 } 892 #endif 893 894 if (check_quietlogin(s, command)) 895 return; 896 897 display_loginmsg(); 898 899 do_motd(); 900 } 901 902 /* 903 * Display the message of the day. 904 */ 905 void 906 do_motd(void) 907 { 908 FILE *f; 909 char buf[256]; 910 911 if (options.print_motd) { 912 #ifdef HAVE_LOGIN_CAP 913 f = fopen(login_getcapstr(lc, "welcome", "/etc/motd", 914 "/etc/motd"), "r"); 915 #else 916 f = fopen("/etc/motd", "r"); 917 #endif 918 if (f) { 919 while (fgets(buf, sizeof(buf), f)) 920 fputs(buf, stdout); 921 fclose(f); 922 } 923 } 924 } 925 926 927 /* 928 * Check for quiet login, either .hushlogin or command given. 929 */ 930 int 931 check_quietlogin(Session *s, const char *command) 932 { 933 char buf[256]; 934 struct passwd *pw = s->pw; 935 struct stat st; 936 937 /* Return 1 if .hushlogin exists or a command given. */ 938 if (command != NULL) 939 return 1; 940 snprintf(buf, sizeof(buf), "%.200s/.hushlogin", pw->pw_dir); 941 #ifdef HAVE_LOGIN_CAP 942 if (login_getcapbool(lc, "hushlogin", 0) || stat(buf, &st) >= 0) 943 return 1; 944 #else 945 if (stat(buf, &st) >= 0) 946 return 1; 947 #endif 948 return 0; 949 } 950 951 /* 952 * Sets the value of the given variable in the environment. If the variable 953 * already exists, its value is overridden. 954 */ 955 void 956 child_set_env(char ***envp, u_int *envsizep, const char *name, 957 const char *value) 958 { 959 char **env; 960 u_int envsize; 961 u_int i, namelen; 962 963 /* 964 * If we're passed an uninitialized list, allocate a single null 965 * entry before continuing. 966 */ 967 if (*envp == NULL && *envsizep == 0) { 968 *envp = xmalloc(sizeof(char *)); 969 *envp[0] = NULL; 970 *envsizep = 1; 971 } 972 973 /* 974 * Find the slot where the value should be stored. If the variable 975 * already exists, we reuse the slot; otherwise we append a new slot 976 * at the end of the array, expanding if necessary. 977 */ 978 env = *envp; 979 namelen = strlen(name); 980 for (i = 0; env[i]; i++) 981 if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=') 982 break; 983 if (env[i]) { 984 /* Reuse the slot. */ 985 free(env[i]); 986 } else { 987 /* New variable. Expand if necessary. */ 988 envsize = *envsizep; 989 if (i >= envsize - 1) { 990 if (envsize >= 1000) 991 fatal("child_set_env: too many env vars"); 992 envsize += 50; 993 env = (*envp) = xrealloc(env, envsize, sizeof(char *)); 994 *envsizep = envsize; 995 } 996 /* Need to set the NULL pointer at end of array beyond the new slot. */ 997 env[i + 1] = NULL; 998 } 999 1000 /* Allocate space and format the variable in the appropriate slot. */ 1001 env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1); 1002 snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value); 1003 } 1004 1005 /* 1006 * Reads environment variables from the given file and adds/overrides them 1007 * into the environment. If the file does not exist, this does nothing. 1008 * Otherwise, it must consist of empty lines, comments (line starts with '#') 1009 * and assignments of the form name=value. No other forms are allowed. 1010 */ 1011 static void 1012 read_environment_file(char ***env, u_int *envsize, 1013 const char *filename) 1014 { 1015 FILE *f; 1016 char buf[4096]; 1017 char *cp, *value; 1018 u_int lineno = 0; 1019 1020 f = fopen(filename, "r"); 1021 if (!f) 1022 return; 1023 1024 while (fgets(buf, sizeof(buf), f)) { 1025 if (++lineno > 1000) 1026 fatal("Too many lines in environment file %s", filename); 1027 for (cp = buf; *cp == ' ' || *cp == '\t'; cp++) 1028 ; 1029 if (!*cp || *cp == '#' || *cp == '\n') 1030 continue; 1031 1032 cp[strcspn(cp, "\n")] = '\0'; 1033 1034 value = strchr(cp, '='); 1035 if (value == NULL) { 1036 fprintf(stderr, "Bad line %u in %.100s\n", lineno, 1037 filename); 1038 continue; 1039 } 1040 /* 1041 * Replace the equals sign by nul, and advance value to 1042 * the value string. 1043 */ 1044 *value = '\0'; 1045 value++; 1046 child_set_env(env, envsize, cp, value); 1047 } 1048 fclose(f); 1049 } 1050 1051 #ifdef HAVE_ETC_DEFAULT_LOGIN 1052 /* 1053 * Return named variable from specified environment, or NULL if not present. 1054 */ 1055 static char * 1056 child_get_env(char **env, const char *name) 1057 { 1058 int i; 1059 size_t len; 1060 1061 len = strlen(name); 1062 for (i=0; env[i] != NULL; i++) 1063 if (strncmp(name, env[i], len) == 0 && env[i][len] == '=') 1064 return(env[i] + len + 1); 1065 return NULL; 1066 } 1067 1068 /* 1069 * Read /etc/default/login. 1070 * We pick up the PATH (or SUPATH for root) and UMASK. 1071 */ 1072 static void 1073 read_etc_default_login(char ***env, u_int *envsize, uid_t uid) 1074 { 1075 char **tmpenv = NULL, *var; 1076 u_int i, tmpenvsize = 0; 1077 u_long mask; 1078 1079 /* 1080 * We don't want to copy the whole file to the child's environment, 1081 * so we use a temporary environment and copy the variables we're 1082 * interested in. 1083 */ 1084 read_environment_file(&tmpenv, &tmpenvsize, "/etc/default/login"); 1085 1086 if (tmpenv == NULL) 1087 return; 1088 1089 if (uid == 0) 1090 var = child_get_env(tmpenv, "SUPATH"); 1091 else 1092 var = child_get_env(tmpenv, "PATH"); 1093 if (var != NULL) 1094 child_set_env(env, envsize, "PATH", var); 1095 1096 if ((var = child_get_env(tmpenv, "UMASK")) != NULL) 1097 if (sscanf(var, "%5lo", &mask) == 1) 1098 umask((mode_t)mask); 1099 1100 for (i = 0; tmpenv[i] != NULL; i++) 1101 free(tmpenv[i]); 1102 free(tmpenv); 1103 } 1104 #endif /* HAVE_ETC_DEFAULT_LOGIN */ 1105 1106 void 1107 copy_environment(char **source, char ***env, u_int *envsize) 1108 { 1109 char *var_name, *var_val; 1110 int i; 1111 1112 if (source == NULL) 1113 return; 1114 1115 for(i = 0; source[i] != NULL; i++) { 1116 var_name = xstrdup(source[i]); 1117 if ((var_val = strstr(var_name, "=")) == NULL) { 1118 free(var_name); 1119 continue; 1120 } 1121 *var_val++ = '\0'; 1122 1123 debug3("Copy environment: %s=%s", var_name, var_val); 1124 child_set_env(env, envsize, var_name, var_val); 1125 1126 free(var_name); 1127 } 1128 } 1129 1130 static char ** 1131 do_setup_env(Session *s, const char *shell) 1132 { 1133 char buf[256]; 1134 u_int i, envsize; 1135 char **env, *laddr; 1136 struct passwd *pw = s->pw; 1137 #if !defined (HAVE_LOGIN_CAP) && !defined (HAVE_CYGWIN) 1138 char *path = NULL; 1139 #else 1140 extern char **environ; 1141 char **senv, **var; 1142 #endif 1143 1144 /* Initialize the environment. */ 1145 envsize = 100; 1146 env = xcalloc(envsize, sizeof(char *)); 1147 env[0] = NULL; 1148 1149 #ifdef HAVE_CYGWIN 1150 /* 1151 * The Windows environment contains some setting which are 1152 * important for a running system. They must not be dropped. 1153 */ 1154 { 1155 char **p; 1156 1157 p = fetch_windows_environment(); 1158 copy_environment(p, &env, &envsize); 1159 free_windows_environment(p); 1160 } 1161 #endif 1162 1163 if (getenv("TZ")) 1164 child_set_env(&env, &envsize, "TZ", getenv("TZ")); 1165 1166 #ifdef GSSAPI 1167 /* Allow any GSSAPI methods that we've used to alter 1168 * the childs environment as they see fit 1169 */ 1170 ssh_gssapi_do_child(&env, &envsize); 1171 #endif 1172 1173 if (!options.use_login) { 1174 /* Set basic environment. */ 1175 for (i = 0; i < s->num_env; i++) 1176 child_set_env(&env, &envsize, s->env[i].name, 1177 s->env[i].val); 1178 1179 child_set_env(&env, &envsize, "USER", pw->pw_name); 1180 child_set_env(&env, &envsize, "LOGNAME", pw->pw_name); 1181 #ifdef _AIX 1182 child_set_env(&env, &envsize, "LOGIN", pw->pw_name); 1183 #endif 1184 child_set_env(&env, &envsize, "HOME", pw->pw_dir); 1185 snprintf(buf, sizeof buf, "%.200s/%.50s", 1186 _PATH_MAILDIR, pw->pw_name); 1187 child_set_env(&env, &envsize, "MAIL", buf); 1188 #ifdef HAVE_LOGIN_CAP 1189 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); 1190 child_set_env(&env, &envsize, "TERM", "su"); 1191 senv = environ; 1192 environ = xmalloc(sizeof(char *)); 1193 *environ = NULL; 1194 (void) setusercontext(lc, pw, pw->pw_uid, 1195 LOGIN_SETENV|LOGIN_SETPATH); 1196 copy_environment(environ, &env, &envsize); 1197 for (var = environ; *var != NULL; ++var) 1198 free(*var); 1199 free(environ); 1200 environ = senv; 1201 #else /* HAVE_LOGIN_CAP */ 1202 # ifndef HAVE_CYGWIN 1203 /* 1204 * There's no standard path on Windows. The path contains 1205 * important components pointing to the system directories, 1206 * needed for loading shared libraries. So the path better 1207 * remains intact here. 1208 */ 1209 # ifdef HAVE_ETC_DEFAULT_LOGIN 1210 read_etc_default_login(&env, &envsize, pw->pw_uid); 1211 path = child_get_env(env, "PATH"); 1212 # endif /* HAVE_ETC_DEFAULT_LOGIN */ 1213 if (path == NULL || *path == '\0') { 1214 child_set_env(&env, &envsize, "PATH", 1215 s->pw->pw_uid == 0 ? 1216 SUPERUSER_PATH : _PATH_STDPATH); 1217 } 1218 # endif /* HAVE_CYGWIN */ 1219 #endif /* HAVE_LOGIN_CAP */ 1220 1221 /* Normal systems set SHELL by default. */ 1222 child_set_env(&env, &envsize, "SHELL", shell); 1223 } 1224 1225 /* Set custom environment options from RSA authentication. */ 1226 if (!options.use_login) { 1227 while (custom_environment) { 1228 struct envstring *ce = custom_environment; 1229 char *str = ce->s; 1230 1231 for (i = 0; str[i] != '=' && str[i]; i++) 1232 ; 1233 if (str[i] == '=') { 1234 str[i] = 0; 1235 child_set_env(&env, &envsize, str, str + i + 1); 1236 } 1237 custom_environment = ce->next; 1238 free(ce->s); 1239 free(ce); 1240 } 1241 } 1242 1243 /* SSH_CLIENT deprecated */ 1244 snprintf(buf, sizeof buf, "%.50s %d %d", 1245 get_remote_ipaddr(), get_remote_port(), get_local_port()); 1246 child_set_env(&env, &envsize, "SSH_CLIENT", buf); 1247 1248 laddr = get_local_ipaddr(packet_get_connection_in()); 1249 snprintf(buf, sizeof buf, "%.50s %d %.50s %d", 1250 get_remote_ipaddr(), get_remote_port(), laddr, get_local_port()); 1251 free(laddr); 1252 child_set_env(&env, &envsize, "SSH_CONNECTION", buf); 1253 1254 if (s->ttyfd != -1) 1255 child_set_env(&env, &envsize, "SSH_TTY", s->tty); 1256 if (s->term) 1257 child_set_env(&env, &envsize, "TERM", s->term); 1258 if (s->display) 1259 child_set_env(&env, &envsize, "DISPLAY", s->display); 1260 if (original_command) 1261 child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND", 1262 original_command); 1263 1264 #ifdef _UNICOS 1265 if (cray_tmpdir[0] != '\0') 1266 child_set_env(&env, &envsize, "TMPDIR", cray_tmpdir); 1267 #endif /* _UNICOS */ 1268 1269 /* 1270 * Since we clear KRB5CCNAME at startup, if it's set now then it 1271 * must have been set by a native authentication method (eg AIX or 1272 * SIA), so copy it to the child. 1273 */ 1274 { 1275 char *cp; 1276 1277 if ((cp = getenv("KRB5CCNAME")) != NULL) 1278 child_set_env(&env, &envsize, "KRB5CCNAME", cp); 1279 } 1280 1281 #ifdef _AIX 1282 { 1283 char *cp; 1284 1285 if ((cp = getenv("AUTHSTATE")) != NULL) 1286 child_set_env(&env, &envsize, "AUTHSTATE", cp); 1287 read_environment_file(&env, &envsize, "/etc/environment"); 1288 } 1289 #endif 1290 #ifdef KRB5 1291 if (s->authctxt->krb5_ccname) 1292 child_set_env(&env, &envsize, "KRB5CCNAME", 1293 s->authctxt->krb5_ccname); 1294 #endif 1295 #ifdef USE_PAM 1296 /* 1297 * Pull in any environment variables that may have 1298 * been set by PAM. 1299 */ 1300 if (options.use_pam) { 1301 char **p; 1302 1303 p = fetch_pam_child_environment(); 1304 copy_environment(p, &env, &envsize); 1305 free_pam_environment(p); 1306 1307 p = fetch_pam_environment(); 1308 copy_environment(p, &env, &envsize); 1309 free_pam_environment(p); 1310 } 1311 #endif /* USE_PAM */ 1312 1313 if (auth_sock_name != NULL) 1314 child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME, 1315 auth_sock_name); 1316 1317 /* read $HOME/.ssh/environment. */ 1318 if (options.permit_user_env && !options.use_login) { 1319 snprintf(buf, sizeof buf, "%.200s/.ssh/environment", 1320 strcmp(pw->pw_dir, "/") ? pw->pw_dir : ""); 1321 read_environment_file(&env, &envsize, buf); 1322 } 1323 if (debug_flag) { 1324 /* dump the environment */ 1325 fprintf(stderr, "Environment:\n"); 1326 for (i = 0; env[i]; i++) 1327 fprintf(stderr, " %.200s\n", env[i]); 1328 } 1329 return env; 1330 } 1331 1332 /* 1333 * Run $HOME/.ssh/rc, /etc/ssh/sshrc, or xauth (whichever is found 1334 * first in this order). 1335 */ 1336 static void 1337 do_rc_files(Session *s, const char *shell) 1338 { 1339 FILE *f = NULL; 1340 char cmd[1024]; 1341 int do_xauth; 1342 struct stat st; 1343 1344 do_xauth = 1345 s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL; 1346 1347 /* ignore _PATH_SSH_USER_RC for subsystems and admin forced commands */ 1348 if (!s->is_subsystem && options.adm_forced_command == NULL && 1349 !no_user_rc && stat(_PATH_SSH_USER_RC, &st) >= 0) { 1350 snprintf(cmd, sizeof cmd, "%s -c '%s %s'", 1351 shell, _PATH_BSHELL, _PATH_SSH_USER_RC); 1352 if (debug_flag) 1353 fprintf(stderr, "Running %s\n", cmd); 1354 f = popen(cmd, "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_USER_RC); 1363 } else if (stat(_PATH_SSH_SYSTEM_RC, &st) >= 0) { 1364 if (debug_flag) 1365 fprintf(stderr, "Running %s %s\n", _PATH_BSHELL, 1366 _PATH_SSH_SYSTEM_RC); 1367 f = popen(_PATH_BSHELL " " _PATH_SSH_SYSTEM_RC, "w"); 1368 if (f) { 1369 if (do_xauth) 1370 fprintf(f, "%s %s\n", s->auth_proto, 1371 s->auth_data); 1372 pclose(f); 1373 } else 1374 fprintf(stderr, "Could not run %s\n", 1375 _PATH_SSH_SYSTEM_RC); 1376 } else if (do_xauth && options.xauth_location != NULL) { 1377 /* Add authority data to .Xauthority if appropriate. */ 1378 if (debug_flag) { 1379 fprintf(stderr, 1380 "Running %.500s remove %.100s\n", 1381 options.xauth_location, s->auth_display); 1382 fprintf(stderr, 1383 "%.500s add %.100s %.100s %.100s\n", 1384 options.xauth_location, s->auth_display, 1385 s->auth_proto, s->auth_data); 1386 } 1387 snprintf(cmd, sizeof cmd, "%s -q -", 1388 options.xauth_location); 1389 f = popen(cmd, "w"); 1390 if (f) { 1391 fprintf(f, "remove %s\n", 1392 s->auth_display); 1393 fprintf(f, "add %s %s %s\n", 1394 s->auth_display, s->auth_proto, 1395 s->auth_data); 1396 pclose(f); 1397 } else { 1398 fprintf(stderr, "Could not run %s\n", 1399 cmd); 1400 } 1401 } 1402 } 1403 1404 static void 1405 do_nologin(struct passwd *pw) 1406 { 1407 FILE *f = NULL; 1408 char buf[1024], *nl, *def_nl = _PATH_NOLOGIN; 1409 struct stat sb; 1410 1411 #ifdef HAVE_LOGIN_CAP 1412 if (login_getcapbool(lc, "ignorenologin", 0) || pw->pw_uid == 0) 1413 return; 1414 nl = login_getcapstr(lc, "nologin", def_nl, def_nl); 1415 #else 1416 if (pw->pw_uid == 0) 1417 return; 1418 nl = def_nl; 1419 #endif 1420 if (stat(nl, &sb) == -1) { 1421 if (nl != def_nl) 1422 free(nl); 1423 return; 1424 } 1425 1426 /* /etc/nologin exists. Print its contents if we can and exit. */ 1427 logit("User %.100s not allowed because %s exists", pw->pw_name, nl); 1428 if ((f = fopen(nl, "r")) != NULL) { 1429 while (fgets(buf, sizeof(buf), f)) 1430 fputs(buf, stderr); 1431 fclose(f); 1432 } 1433 exit(254); 1434 } 1435 1436 /* 1437 * Chroot into a directory after checking it for safety: all path components 1438 * must be root-owned directories with strict permissions. 1439 */ 1440 static void 1441 safely_chroot(const char *path, uid_t uid) 1442 { 1443 const char *cp; 1444 char component[MAXPATHLEN]; 1445 struct stat st; 1446 1447 if (*path != '/') 1448 fatal("chroot path does not begin at root"); 1449 if (strlen(path) >= sizeof(component)) 1450 fatal("chroot path too long"); 1451 1452 /* 1453 * Descend the path, checking that each component is a 1454 * root-owned directory with strict permissions. 1455 */ 1456 for (cp = path; cp != NULL;) { 1457 if ((cp = strchr(cp, '/')) == NULL) 1458 strlcpy(component, path, sizeof(component)); 1459 else { 1460 cp++; 1461 memcpy(component, path, cp - path); 1462 component[cp - path] = '\0'; 1463 } 1464 1465 debug3("%s: checking '%s'", __func__, component); 1466 1467 if (stat(component, &st) != 0) 1468 fatal("%s: stat(\"%s\"): %s", __func__, 1469 component, strerror(errno)); 1470 if (st.st_uid != 0 || (st.st_mode & 022) != 0) 1471 fatal("bad ownership or modes for chroot " 1472 "directory %s\"%s\"", 1473 cp == NULL ? "" : "component ", component); 1474 if (!S_ISDIR(st.st_mode)) 1475 fatal("chroot path %s\"%s\" is not a directory", 1476 cp == NULL ? "" : "component ", component); 1477 1478 } 1479 1480 if (chdir(path) == -1) 1481 fatal("Unable to chdir to chroot path \"%s\": " 1482 "%s", path, strerror(errno)); 1483 if (chroot(path) == -1) 1484 fatal("chroot(\"%s\"): %s", path, strerror(errno)); 1485 if (chdir("/") == -1) 1486 fatal("%s: chdir(/) after chroot: %s", 1487 __func__, strerror(errno)); 1488 verbose("Changed root directory to \"%s\"", path); 1489 } 1490 1491 /* Set login name, uid, gid, and groups. */ 1492 void 1493 do_setusercontext(struct passwd *pw) 1494 { 1495 char *chroot_path, *tmp; 1496 1497 platform_setusercontext(pw); 1498 1499 if (platform_privileged_uidswap()) { 1500 #ifdef HAVE_LOGIN_CAP 1501 if (setusercontext(lc, pw, pw->pw_uid, 1502 (LOGIN_SETALL & ~(LOGIN_SETENV|LOGIN_SETPATH|LOGIN_SETUSER))) < 0) { 1503 perror("unable to set user context"); 1504 exit(1); 1505 } 1506 #else 1507 if (setlogin(pw->pw_name) < 0) 1508 error("setlogin failed: %s", strerror(errno)); 1509 if (setgid(pw->pw_gid) < 0) { 1510 perror("setgid"); 1511 exit(1); 1512 } 1513 /* Initialize the group list. */ 1514 if (initgroups(pw->pw_name, pw->pw_gid) < 0) { 1515 perror("initgroups"); 1516 exit(1); 1517 } 1518 endgrent(); 1519 #endif 1520 1521 platform_setusercontext_post_groups(pw); 1522 1523 if (options.chroot_directory != NULL && 1524 strcasecmp(options.chroot_directory, "none") != 0) { 1525 tmp = tilde_expand_filename(options.chroot_directory, 1526 pw->pw_uid); 1527 chroot_path = percent_expand(tmp, "h", pw->pw_dir, 1528 "u", pw->pw_name, (char *)NULL); 1529 safely_chroot(chroot_path, pw->pw_uid); 1530 free(tmp); 1531 free(chroot_path); 1532 /* Make sure we don't attempt to chroot again */ 1533 free(options.chroot_directory); 1534 options.chroot_directory = NULL; 1535 } 1536 1537 #ifdef HAVE_LOGIN_CAP 1538 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUSER) < 0) { 1539 perror("unable to set user context (setuser)"); 1540 exit(1); 1541 } 1542 /* 1543 * FreeBSD's setusercontext() will not apply the user's 1544 * own umask setting unless running with the user's UID. 1545 */ 1546 (void) setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUMASK); 1547 #else 1548 /* Permanently switch to the desired uid. */ 1549 permanently_set_uid(pw); 1550 #endif 1551 } else if (options.chroot_directory != NULL && 1552 strcasecmp(options.chroot_directory, "none") != 0) { 1553 fatal("server lacks privileges to chroot to ChrootDirectory"); 1554 } 1555 1556 if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) 1557 fatal("Failed to set uids to %u.", (u_int) pw->pw_uid); 1558 } 1559 1560 static void 1561 do_pwchange(Session *s) 1562 { 1563 fflush(NULL); 1564 fprintf(stderr, "WARNING: Your password has expired.\n"); 1565 if (s->ttyfd != -1) { 1566 fprintf(stderr, 1567 "You must change your password now and login again!\n"); 1568 #ifdef WITH_SELINUX 1569 setexeccon(NULL); 1570 #endif 1571 #ifdef PASSWD_NEEDS_USERNAME 1572 execl(_PATH_PASSWD_PROG, "passwd", s->pw->pw_name, 1573 (char *)NULL); 1574 #else 1575 execl(_PATH_PASSWD_PROG, "passwd", (char *)NULL); 1576 #endif 1577 perror("passwd"); 1578 } else { 1579 fprintf(stderr, 1580 "Password change required but no TTY available.\n"); 1581 } 1582 exit(1); 1583 } 1584 1585 static void 1586 launch_login(struct passwd *pw, const char *hostname) 1587 { 1588 /* Launch login(1). */ 1589 1590 execl(LOGIN_PROGRAM, "login", "-h", hostname, 1591 #ifdef xxxLOGIN_NEEDS_TERM 1592 (s->term ? s->term : "unknown"), 1593 #endif /* LOGIN_NEEDS_TERM */ 1594 #ifdef LOGIN_NO_ENDOPT 1595 "-p", "-f", pw->pw_name, (char *)NULL); 1596 #else 1597 "-p", "-f", "--", pw->pw_name, (char *)NULL); 1598 #endif 1599 1600 /* Login couldn't be executed, die. */ 1601 1602 perror("login"); 1603 exit(1); 1604 } 1605 1606 static void 1607 child_close_fds(void) 1608 { 1609 extern AuthenticationConnection *auth_conn; 1610 1611 if (auth_conn) { 1612 ssh_close_authentication_connection(auth_conn); 1613 auth_conn = NULL; 1614 } 1615 1616 if (packet_get_connection_in() == packet_get_connection_out()) 1617 close(packet_get_connection_in()); 1618 else { 1619 close(packet_get_connection_in()); 1620 close(packet_get_connection_out()); 1621 } 1622 /* 1623 * Close all descriptors related to channels. They will still remain 1624 * open in the parent. 1625 */ 1626 /* XXX better use close-on-exec? -markus */ 1627 channel_close_all(); 1628 1629 /* 1630 * Close any extra file descriptors. Note that there may still be 1631 * descriptors left by system functions. They will be closed later. 1632 */ 1633 endpwent(); 1634 1635 /* 1636 * Close any extra open file descriptors so that we don't have them 1637 * hanging around in clients. Note that we want to do this after 1638 * initgroups, because at least on Solaris 2.3 it leaves file 1639 * descriptors open. 1640 */ 1641 closefrom(STDERR_FILENO + 1); 1642 } 1643 1644 /* 1645 * Performs common processing for the child, such as setting up the 1646 * environment, closing extra file descriptors, setting the user and group 1647 * ids, and executing the command or shell. 1648 */ 1649 #define ARGV_MAX 10 1650 void 1651 do_child(Session *s, const char *command) 1652 { 1653 extern char **environ; 1654 char **env; 1655 char *argv[ARGV_MAX]; 1656 const char *shell, *shell0, *hostname = NULL; 1657 struct passwd *pw = s->pw; 1658 int r = 0; 1659 1660 /* remove hostkey from the child's memory */ 1661 destroy_sensitive_data(); 1662 1663 /* Force a password change */ 1664 if (s->authctxt->force_pwchange) { 1665 do_setusercontext(pw); 1666 child_close_fds(); 1667 do_pwchange(s); 1668 exit(1); 1669 } 1670 1671 /* login(1) is only called if we execute the login shell */ 1672 if (options.use_login && command != NULL) 1673 options.use_login = 0; 1674 1675 #ifdef _UNICOS 1676 cray_setup(pw->pw_uid, pw->pw_name, command); 1677 #endif /* _UNICOS */ 1678 1679 /* 1680 * Login(1) does this as well, and it needs uid 0 for the "-h" 1681 * switch, so we let login(1) to this for us. 1682 */ 1683 if (!options.use_login) { 1684 #ifdef HAVE_OSF_SIA 1685 session_setup_sia(pw, s->ttyfd == -1 ? NULL : s->tty); 1686 if (!check_quietlogin(s, command)) 1687 do_motd(); 1688 #else /* HAVE_OSF_SIA */ 1689 /* When PAM is enabled we rely on it to do the nologin check */ 1690 if (!options.use_pam) 1691 do_nologin(pw); 1692 do_setusercontext(pw); 1693 /* 1694 * PAM session modules in do_setusercontext may have 1695 * generated messages, so if this in an interactive 1696 * login then display them too. 1697 */ 1698 if (!check_quietlogin(s, command)) 1699 display_loginmsg(); 1700 #endif /* HAVE_OSF_SIA */ 1701 } 1702 1703 #ifdef USE_PAM 1704 if (options.use_pam && !options.use_login && !is_pam_session_open()) { 1705 debug3("PAM session not opened, exiting"); 1706 display_loginmsg(); 1707 exit(254); 1708 } 1709 #endif 1710 1711 /* 1712 * Get the shell from the password data. An empty shell field is 1713 * legal, and means /bin/sh. 1714 */ 1715 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; 1716 1717 /* 1718 * Make sure $SHELL points to the shell from the password file, 1719 * even if shell is overridden from login.conf 1720 */ 1721 env = do_setup_env(s, shell); 1722 1723 #ifdef HAVE_LOGIN_CAP 1724 shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell); 1725 #endif 1726 1727 /* we have to stash the hostname before we close our socket. */ 1728 if (options.use_login) 1729 hostname = get_remote_name_or_ip(utmp_len, 1730 options.use_dns); 1731 /* 1732 * Close the connection descriptors; note that this is the child, and 1733 * the server will still have the socket open, and it is important 1734 * that we do not shutdown it. Note that the descriptors cannot be 1735 * closed before building the environment, as we call 1736 * get_remote_ipaddr there. 1737 */ 1738 child_close_fds(); 1739 1740 /* 1741 * Must take new environment into use so that .ssh/rc, 1742 * /etc/ssh/sshrc and xauth are run in the proper environment. 1743 */ 1744 environ = env; 1745 1746 #if defined(KRB5) && defined(USE_AFS) 1747 /* 1748 * At this point, we check to see if AFS is active and if we have 1749 * a valid Kerberos 5 TGT. If so, it seems like a good idea to see 1750 * if we can (and need to) extend the ticket into an AFS token. If 1751 * we don't do this, we run into potential problems if the user's 1752 * home directory is in AFS and it's not world-readable. 1753 */ 1754 1755 if (options.kerberos_get_afs_token && k_hasafs() && 1756 (s->authctxt->krb5_ctx != NULL)) { 1757 char cell[64]; 1758 1759 debug("Getting AFS token"); 1760 1761 k_setpag(); 1762 1763 if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0) 1764 krb5_afslog(s->authctxt->krb5_ctx, 1765 s->authctxt->krb5_fwd_ccache, cell, NULL); 1766 1767 krb5_afslog_home(s->authctxt->krb5_ctx, 1768 s->authctxt->krb5_fwd_ccache, NULL, NULL, pw->pw_dir); 1769 } 1770 #endif 1771 1772 /* Change current directory to the user's home directory. */ 1773 if (chdir(pw->pw_dir) < 0) { 1774 /* Suppress missing homedir warning for chroot case */ 1775 #ifdef HAVE_LOGIN_CAP 1776 r = login_getcapbool(lc, "requirehome", 0); 1777 #endif 1778 if (r || options.chroot_directory == NULL || 1779 strcasecmp(options.chroot_directory, "none") == 0) 1780 fprintf(stderr, "Could not chdir to home " 1781 "directory %s: %s\n", pw->pw_dir, 1782 strerror(errno)); 1783 if (r) 1784 exit(1); 1785 } 1786 1787 closefrom(STDERR_FILENO + 1); 1788 1789 if (!options.use_login) 1790 do_rc_files(s, shell); 1791 1792 /* restore SIGPIPE for child */ 1793 signal(SIGPIPE, SIG_DFL); 1794 1795 if (s->is_subsystem == SUBSYSTEM_INT_SFTP_ERROR) { 1796 printf("This service allows sftp connections only.\n"); 1797 fflush(NULL); 1798 exit(1); 1799 } else if (s->is_subsystem == SUBSYSTEM_INT_SFTP) { 1800 extern int optind, optreset; 1801 int i; 1802 char *p, *args; 1803 1804 setproctitle("%s@%s", s->pw->pw_name, INTERNAL_SFTP_NAME); 1805 args = xstrdup(command ? command : "sftp-server"); 1806 for (i = 0, (p = strtok(args, " ")); p; (p = strtok(NULL, " "))) 1807 if (i < ARGV_MAX - 1) 1808 argv[i++] = p; 1809 argv[i] = NULL; 1810 optind = optreset = 1; 1811 __progname = argv[0]; 1812 #ifdef WITH_SELINUX 1813 ssh_selinux_change_context("sftpd_t"); 1814 #endif 1815 exit(sftp_server_main(i, argv, s->pw)); 1816 } 1817 1818 fflush(NULL); 1819 1820 if (options.use_login) { 1821 launch_login(pw, hostname); 1822 /* NEVERREACHED */ 1823 } 1824 1825 /* Get the last component of the shell name. */ 1826 if ((shell0 = strrchr(shell, '/')) != NULL) 1827 shell0++; 1828 else 1829 shell0 = shell; 1830 1831 /* 1832 * If we have no command, execute the shell. In this case, the shell 1833 * name to be passed in argv[0] is preceded by '-' to indicate that 1834 * this is a login shell. 1835 */ 1836 if (!command) { 1837 char argv0[256]; 1838 1839 /* Start the shell. Set initial character to '-'. */ 1840 argv0[0] = '-'; 1841 1842 if (strlcpy(argv0 + 1, shell0, sizeof(argv0) - 1) 1843 >= sizeof(argv0) - 1) { 1844 errno = EINVAL; 1845 perror(shell); 1846 exit(1); 1847 } 1848 1849 /* Execute the shell. */ 1850 argv[0] = argv0; 1851 argv[1] = NULL; 1852 execve(shell, argv, env); 1853 1854 /* Executing the shell failed. */ 1855 perror(shell); 1856 exit(1); 1857 } 1858 /* 1859 * Execute the command using the user's shell. This uses the -c 1860 * option to execute the command. 1861 */ 1862 argv[0] = (char *) shell0; 1863 argv[1] = "-c"; 1864 argv[2] = (char *) command; 1865 argv[3] = NULL; 1866 execve(shell, argv, env); 1867 perror(shell); 1868 exit(1); 1869 } 1870 1871 void 1872 session_unused(int id) 1873 { 1874 debug3("%s: session id %d unused", __func__, id); 1875 if (id >= options.max_sessions || 1876 id >= sessions_nalloc) { 1877 fatal("%s: insane session id %d (max %d nalloc %d)", 1878 __func__, id, options.max_sessions, sessions_nalloc); 1879 } 1880 bzero(&sessions[id], sizeof(*sessions)); 1881 sessions[id].self = id; 1882 sessions[id].used = 0; 1883 sessions[id].chanid = -1; 1884 sessions[id].ptyfd = -1; 1885 sessions[id].ttyfd = -1; 1886 sessions[id].ptymaster = -1; 1887 sessions[id].x11_chanids = NULL; 1888 sessions[id].next_unused = sessions_first_unused; 1889 sessions_first_unused = id; 1890 } 1891 1892 Session * 1893 session_new(void) 1894 { 1895 Session *s, *tmp; 1896 1897 if (sessions_first_unused == -1) { 1898 if (sessions_nalloc >= options.max_sessions) 1899 return NULL; 1900 debug2("%s: allocate (allocated %d max %d)", 1901 __func__, sessions_nalloc, options.max_sessions); 1902 tmp = xrealloc(sessions, sessions_nalloc + 1, 1903 sizeof(*sessions)); 1904 if (tmp == NULL) { 1905 error("%s: cannot allocate %d sessions", 1906 __func__, sessions_nalloc + 1); 1907 return NULL; 1908 } 1909 sessions = tmp; 1910 session_unused(sessions_nalloc++); 1911 } 1912 1913 if (sessions_first_unused >= sessions_nalloc || 1914 sessions_first_unused < 0) { 1915 fatal("%s: insane first_unused %d max %d nalloc %d", 1916 __func__, sessions_first_unused, options.max_sessions, 1917 sessions_nalloc); 1918 } 1919 1920 s = &sessions[sessions_first_unused]; 1921 if (s->used) { 1922 fatal("%s: session %d already used", 1923 __func__, sessions_first_unused); 1924 } 1925 sessions_first_unused = s->next_unused; 1926 s->used = 1; 1927 s->next_unused = -1; 1928 debug("session_new: session %d", s->self); 1929 1930 return s; 1931 } 1932 1933 static void 1934 session_dump(void) 1935 { 1936 int i; 1937 for (i = 0; i < sessions_nalloc; i++) { 1938 Session *s = &sessions[i]; 1939 1940 debug("dump: used %d next_unused %d session %d %p " 1941 "channel %d pid %ld", 1942 s->used, 1943 s->next_unused, 1944 s->self, 1945 s, 1946 s->chanid, 1947 (long)s->pid); 1948 } 1949 } 1950 1951 int 1952 session_open(Authctxt *authctxt, int chanid) 1953 { 1954 Session *s = session_new(); 1955 debug("session_open: channel %d", chanid); 1956 if (s == NULL) { 1957 error("no more sessions"); 1958 return 0; 1959 } 1960 s->authctxt = authctxt; 1961 s->pw = authctxt->pw; 1962 if (s->pw == NULL || !authctxt->valid) 1963 fatal("no user for session %d", s->self); 1964 debug("session_open: session %d: link with channel %d", s->self, chanid); 1965 s->chanid = chanid; 1966 return 1; 1967 } 1968 1969 Session * 1970 session_by_tty(char *tty) 1971 { 1972 int i; 1973 for (i = 0; i < sessions_nalloc; i++) { 1974 Session *s = &sessions[i]; 1975 if (s->used && s->ttyfd != -1 && strcmp(s->tty, tty) == 0) { 1976 debug("session_by_tty: session %d tty %s", i, tty); 1977 return s; 1978 } 1979 } 1980 debug("session_by_tty: unknown tty %.100s", tty); 1981 session_dump(); 1982 return NULL; 1983 } 1984 1985 static Session * 1986 session_by_channel(int id) 1987 { 1988 int i; 1989 for (i = 0; i < sessions_nalloc; i++) { 1990 Session *s = &sessions[i]; 1991 if (s->used && s->chanid == id) { 1992 debug("session_by_channel: session %d channel %d", 1993 i, id); 1994 return s; 1995 } 1996 } 1997 debug("session_by_channel: unknown channel %d", id); 1998 session_dump(); 1999 return NULL; 2000 } 2001 2002 static Session * 2003 session_by_x11_channel(int id) 2004 { 2005 int i, j; 2006 2007 for (i = 0; i < sessions_nalloc; i++) { 2008 Session *s = &sessions[i]; 2009 2010 if (s->x11_chanids == NULL || !s->used) 2011 continue; 2012 for (j = 0; s->x11_chanids[j] != -1; j++) { 2013 if (s->x11_chanids[j] == id) { 2014 debug("session_by_x11_channel: session %d " 2015 "channel %d", s->self, id); 2016 return s; 2017 } 2018 } 2019 } 2020 debug("session_by_x11_channel: unknown channel %d", id); 2021 session_dump(); 2022 return NULL; 2023 } 2024 2025 static Session * 2026 session_by_pid(pid_t pid) 2027 { 2028 int i; 2029 debug("session_by_pid: pid %ld", (long)pid); 2030 for (i = 0; i < sessions_nalloc; i++) { 2031 Session *s = &sessions[i]; 2032 if (s->used && s->pid == pid) 2033 return s; 2034 } 2035 error("session_by_pid: unknown pid %ld", (long)pid); 2036 session_dump(); 2037 return NULL; 2038 } 2039 2040 static int 2041 session_window_change_req(Session *s) 2042 { 2043 s->col = packet_get_int(); 2044 s->row = packet_get_int(); 2045 s->xpixel = packet_get_int(); 2046 s->ypixel = packet_get_int(); 2047 packet_check_eom(); 2048 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 2049 return 1; 2050 } 2051 2052 static int 2053 session_pty_req(Session *s) 2054 { 2055 u_int len; 2056 int n_bytes; 2057 2058 if (no_pty_flag) { 2059 debug("Allocating a pty not permitted for this authentication."); 2060 return 0; 2061 } 2062 if (s->ttyfd != -1) { 2063 packet_disconnect("Protocol error: you already have a pty."); 2064 return 0; 2065 } 2066 2067 s->term = packet_get_string(&len); 2068 2069 if (compat20) { 2070 s->col = packet_get_int(); 2071 s->row = packet_get_int(); 2072 } else { 2073 s->row = packet_get_int(); 2074 s->col = packet_get_int(); 2075 } 2076 s->xpixel = packet_get_int(); 2077 s->ypixel = packet_get_int(); 2078 2079 if (strcmp(s->term, "") == 0) { 2080 free(s->term); 2081 s->term = NULL; 2082 } 2083 2084 /* Allocate a pty and open it. */ 2085 debug("Allocating pty."); 2086 if (!PRIVSEP(pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, 2087 sizeof(s->tty)))) { 2088 free(s->term); 2089 s->term = NULL; 2090 s->ptyfd = -1; 2091 s->ttyfd = -1; 2092 error("session_pty_req: session %d alloc failed", s->self); 2093 return 0; 2094 } 2095 debug("session_pty_req: session %d alloc %s", s->self, s->tty); 2096 2097 /* for SSH1 the tty modes length is not given */ 2098 if (!compat20) 2099 n_bytes = packet_remaining(); 2100 tty_parse_modes(s->ttyfd, &n_bytes); 2101 2102 if (!use_privsep) 2103 pty_setowner(s->pw, s->tty); 2104 2105 /* Set window size from the packet. */ 2106 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 2107 2108 packet_check_eom(); 2109 session_proctitle(s); 2110 return 1; 2111 } 2112 2113 static int 2114 session_subsystem_req(Session *s) 2115 { 2116 struct stat st; 2117 u_int len; 2118 int success = 0; 2119 char *prog, *cmd, *subsys = packet_get_string(&len); 2120 u_int i; 2121 2122 packet_check_eom(); 2123 logit("subsystem request for %.100s by user %s", subsys, 2124 s->pw->pw_name); 2125 2126 for (i = 0; i < options.num_subsystems; i++) { 2127 if (strcmp(subsys, options.subsystem_name[i]) == 0) { 2128 prog = options.subsystem_command[i]; 2129 cmd = options.subsystem_args[i]; 2130 if (strcmp(INTERNAL_SFTP_NAME, prog) == 0) { 2131 s->is_subsystem = SUBSYSTEM_INT_SFTP; 2132 debug("subsystem: %s", prog); 2133 } else { 2134 if (stat(prog, &st) < 0) 2135 debug("subsystem: cannot stat %s: %s", 2136 prog, strerror(errno)); 2137 s->is_subsystem = SUBSYSTEM_EXT; 2138 debug("subsystem: exec() %s", cmd); 2139 } 2140 success = do_exec(s, cmd) == 0; 2141 break; 2142 } 2143 } 2144 2145 if (!success) 2146 logit("subsystem request for %.100s failed, subsystem not found", 2147 subsys); 2148 2149 free(subsys); 2150 return success; 2151 } 2152 2153 static int 2154 session_x11_req(Session *s) 2155 { 2156 int success; 2157 2158 if (s->auth_proto != NULL || s->auth_data != NULL) { 2159 error("session_x11_req: session %d: " 2160 "x11 forwarding already active", s->self); 2161 return 0; 2162 } 2163 s->single_connection = packet_get_char(); 2164 s->auth_proto = packet_get_string(NULL); 2165 s->auth_data = packet_get_string(NULL); 2166 s->screen = packet_get_int(); 2167 packet_check_eom(); 2168 2169 success = session_setup_x11fwd(s); 2170 if (!success) { 2171 free(s->auth_proto); 2172 free(s->auth_data); 2173 s->auth_proto = NULL; 2174 s->auth_data = NULL; 2175 } 2176 return success; 2177 } 2178 2179 static int 2180 session_shell_req(Session *s) 2181 { 2182 packet_check_eom(); 2183 return do_exec(s, NULL) == 0; 2184 } 2185 2186 static int 2187 session_exec_req(Session *s) 2188 { 2189 u_int len, success; 2190 2191 char *command = packet_get_string(&len); 2192 packet_check_eom(); 2193 success = do_exec(s, command) == 0; 2194 free(command); 2195 return success; 2196 } 2197 2198 static int 2199 session_break_req(Session *s) 2200 { 2201 2202 packet_get_int(); /* ignored */ 2203 packet_check_eom(); 2204 2205 if (s->ptymaster == -1 || tcsendbreak(s->ptymaster, 0) < 0) 2206 return 0; 2207 return 1; 2208 } 2209 2210 static int 2211 session_env_req(Session *s) 2212 { 2213 char *name, *val; 2214 u_int name_len, val_len, i; 2215 2216 name = packet_get_string(&name_len); 2217 val = packet_get_string(&val_len); 2218 packet_check_eom(); 2219 2220 /* Don't set too many environment variables */ 2221 if (s->num_env > 128) { 2222 debug2("Ignoring env request %s: too many env vars", name); 2223 goto fail; 2224 } 2225 2226 for (i = 0; i < options.num_accept_env; i++) { 2227 if (match_pattern(name, options.accept_env[i])) { 2228 debug2("Setting env %d: %s=%s", s->num_env, name, val); 2229 s->env = xrealloc(s->env, s->num_env + 1, 2230 sizeof(*s->env)); 2231 s->env[s->num_env].name = name; 2232 s->env[s->num_env].val = val; 2233 s->num_env++; 2234 return (1); 2235 } 2236 } 2237 debug2("Ignoring env request %s: disallowed name", name); 2238 2239 fail: 2240 free(name); 2241 free(val); 2242 return (0); 2243 } 2244 2245 static int 2246 session_auth_agent_req(Session *s) 2247 { 2248 static int called = 0; 2249 packet_check_eom(); 2250 if (no_agent_forwarding_flag || !options.allow_agent_forwarding) { 2251 debug("session_auth_agent_req: no_agent_forwarding_flag"); 2252 return 0; 2253 } 2254 if (called) { 2255 return 0; 2256 } else { 2257 called = 1; 2258 return auth_input_request_forwarding(s->pw); 2259 } 2260 } 2261 2262 int 2263 session_input_channel_req(Channel *c, const char *rtype) 2264 { 2265 int success = 0; 2266 Session *s; 2267 2268 if ((s = session_by_channel(c->self)) == NULL) { 2269 logit("session_input_channel_req: no session %d req %.100s", 2270 c->self, rtype); 2271 return 0; 2272 } 2273 debug("session_input_channel_req: session %d req %s", s->self, rtype); 2274 2275 /* 2276 * a session is in LARVAL state until a shell, a command 2277 * or a subsystem is executed 2278 */ 2279 if (c->type == SSH_CHANNEL_LARVAL) { 2280 if (strcmp(rtype, "shell") == 0) { 2281 success = session_shell_req(s); 2282 } else if (strcmp(rtype, "exec") == 0) { 2283 success = session_exec_req(s); 2284 } else if (strcmp(rtype, "pty-req") == 0) { 2285 success = session_pty_req(s); 2286 } else if (strcmp(rtype, "x11-req") == 0) { 2287 success = session_x11_req(s); 2288 } else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) { 2289 success = session_auth_agent_req(s); 2290 } else if (strcmp(rtype, "subsystem") == 0) { 2291 success = session_subsystem_req(s); 2292 } else if (strcmp(rtype, "env") == 0) { 2293 success = session_env_req(s); 2294 } 2295 } 2296 if (strcmp(rtype, "window-change") == 0) { 2297 success = session_window_change_req(s); 2298 } else if (strcmp(rtype, "break") == 0) { 2299 success = session_break_req(s); 2300 } 2301 2302 return success; 2303 } 2304 2305 void 2306 session_set_fds(Session *s, int fdin, int fdout, int fderr, int ignore_fderr, 2307 int is_tty) 2308 { 2309 if (!compat20) 2310 fatal("session_set_fds: called for proto != 2.0"); 2311 /* 2312 * now that have a child and a pipe to the child, 2313 * we can activate our channel and register the fd's 2314 */ 2315 if (s->chanid == -1) 2316 fatal("no channel for session %d", s->self); 2317 if (options.hpn_disabled) 2318 channel_set_fds(s->chanid, fdout, fdin, fderr, 2319 ignore_fderr ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ, 2320 1, is_tty, CHAN_SES_WINDOW_DEFAULT); 2321 else 2322 channel_set_fds(s->chanid, fdout, fdin, fderr, 2323 ignore_fderr ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ, 2324 1, is_tty, options.hpn_buffer_size); 2325 } 2326 2327 /* 2328 * Function to perform pty cleanup. Also called if we get aborted abnormally 2329 * (e.g., due to a dropped connection). 2330 */ 2331 void 2332 session_pty_cleanup2(Session *s) 2333 { 2334 if (s == NULL) { 2335 error("session_pty_cleanup: no session"); 2336 return; 2337 } 2338 if (s->ttyfd == -1) 2339 return; 2340 2341 debug("session_pty_cleanup: session %d release %s", s->self, s->tty); 2342 2343 /* Record that the user has logged out. */ 2344 if (s->pid != 0) 2345 record_logout(s->pid, s->tty, s->pw->pw_name); 2346 2347 /* Release the pseudo-tty. */ 2348 if (getuid() == 0) 2349 pty_release(s->tty); 2350 2351 /* 2352 * Close the server side of the socket pairs. We must do this after 2353 * the pty cleanup, so that another process doesn't get this pty 2354 * while we're still cleaning up. 2355 */ 2356 if (s->ptymaster != -1 && close(s->ptymaster) < 0) 2357 error("close(s->ptymaster/%d): %s", 2358 s->ptymaster, strerror(errno)); 2359 2360 /* unlink pty from session */ 2361 s->ttyfd = -1; 2362 } 2363 2364 void 2365 session_pty_cleanup(Session *s) 2366 { 2367 PRIVSEP(session_pty_cleanup2(s)); 2368 } 2369 2370 static char * 2371 sig2name(int sig) 2372 { 2373 #define SSH_SIG(x) if (sig == SIG ## x) return #x 2374 SSH_SIG(ABRT); 2375 SSH_SIG(ALRM); 2376 SSH_SIG(FPE); 2377 SSH_SIG(HUP); 2378 SSH_SIG(ILL); 2379 SSH_SIG(INT); 2380 SSH_SIG(KILL); 2381 SSH_SIG(PIPE); 2382 SSH_SIG(QUIT); 2383 SSH_SIG(SEGV); 2384 SSH_SIG(TERM); 2385 SSH_SIG(USR1); 2386 SSH_SIG(USR2); 2387 #undef SSH_SIG 2388 return "SIG@openssh.com"; 2389 } 2390 2391 static void 2392 session_close_x11(int id) 2393 { 2394 Channel *c; 2395 2396 if ((c = channel_by_id(id)) == NULL) { 2397 debug("session_close_x11: x11 channel %d missing", id); 2398 } else { 2399 /* Detach X11 listener */ 2400 debug("session_close_x11: detach x11 channel %d", id); 2401 channel_cancel_cleanup(id); 2402 if (c->ostate != CHAN_OUTPUT_CLOSED) 2403 chan_mark_dead(c); 2404 } 2405 } 2406 2407 static void 2408 session_close_single_x11(int id, void *arg) 2409 { 2410 Session *s; 2411 u_int i; 2412 2413 debug3("session_close_single_x11: channel %d", id); 2414 channel_cancel_cleanup(id); 2415 if ((s = session_by_x11_channel(id)) == NULL) 2416 fatal("session_close_single_x11: no x11 channel %d", id); 2417 for (i = 0; s->x11_chanids[i] != -1; i++) { 2418 debug("session_close_single_x11: session %d: " 2419 "closing channel %d", s->self, s->x11_chanids[i]); 2420 /* 2421 * The channel "id" is already closing, but make sure we 2422 * close all of its siblings. 2423 */ 2424 if (s->x11_chanids[i] != id) 2425 session_close_x11(s->x11_chanids[i]); 2426 } 2427 free(s->x11_chanids); 2428 s->x11_chanids = NULL; 2429 free(s->display); 2430 s->display = NULL; 2431 free(s->auth_proto); 2432 s->auth_proto = NULL; 2433 free(s->auth_data); 2434 s->auth_data = NULL; 2435 free(s->auth_display); 2436 s->auth_display = NULL; 2437 } 2438 2439 static void 2440 session_exit_message(Session *s, int status) 2441 { 2442 Channel *c; 2443 2444 if ((c = channel_lookup(s->chanid)) == NULL) 2445 fatal("session_exit_message: session %d: no channel %d", 2446 s->self, s->chanid); 2447 debug("session_exit_message: session %d channel %d pid %ld", 2448 s->self, s->chanid, (long)s->pid); 2449 2450 if (WIFEXITED(status)) { 2451 channel_request_start(s->chanid, "exit-status", 0); 2452 packet_put_int(WEXITSTATUS(status)); 2453 packet_send(); 2454 } else if (WIFSIGNALED(status)) { 2455 channel_request_start(s->chanid, "exit-signal", 0); 2456 packet_put_cstring(sig2name(WTERMSIG(status))); 2457 #ifdef WCOREDUMP 2458 packet_put_char(WCOREDUMP(status)? 1 : 0); 2459 #else /* WCOREDUMP */ 2460 packet_put_char(0); 2461 #endif /* WCOREDUMP */ 2462 packet_put_cstring(""); 2463 packet_put_cstring(""); 2464 packet_send(); 2465 } else { 2466 /* Some weird exit cause. Just exit. */ 2467 packet_disconnect("wait returned status %04x.", status); 2468 } 2469 2470 /* disconnect channel */ 2471 debug("session_exit_message: release channel %d", s->chanid); 2472 2473 /* 2474 * Adjust cleanup callback attachment to send close messages when 2475 * the channel gets EOF. The session will be then be closed 2476 * by session_close_by_channel when the childs close their fds. 2477 */ 2478 channel_register_cleanup(c->self, session_close_by_channel, 1); 2479 2480 /* 2481 * emulate a write failure with 'chan_write_failed', nobody will be 2482 * interested in data we write. 2483 * Note that we must not call 'chan_read_failed', since there could 2484 * be some more data waiting in the pipe. 2485 */ 2486 if (c->ostate != CHAN_OUTPUT_CLOSED) 2487 chan_write_failed(c); 2488 } 2489 2490 void 2491 session_close(Session *s) 2492 { 2493 u_int i; 2494 2495 debug("session_close: session %d pid %ld", s->self, (long)s->pid); 2496 if (s->ttyfd != -1) 2497 session_pty_cleanup(s); 2498 free(s->term); 2499 free(s->display); 2500 free(s->x11_chanids); 2501 free(s->auth_display); 2502 free(s->auth_data); 2503 free(s->auth_proto); 2504 if (s->env != NULL) { 2505 for (i = 0; i < s->num_env; i++) { 2506 free(s->env[i].name); 2507 free(s->env[i].val); 2508 } 2509 free(s->env); 2510 } 2511 session_proctitle(s); 2512 session_unused(s->self); 2513 } 2514 2515 void 2516 session_close_by_pid(pid_t pid, int status) 2517 { 2518 Session *s = session_by_pid(pid); 2519 if (s == NULL) { 2520 debug("session_close_by_pid: no session for pid %ld", 2521 (long)pid); 2522 return; 2523 } 2524 if (s->chanid != -1) 2525 session_exit_message(s, status); 2526 if (s->ttyfd != -1) 2527 session_pty_cleanup(s); 2528 s->pid = 0; 2529 } 2530 2531 /* 2532 * this is called when a channel dies before 2533 * the session 'child' itself dies 2534 */ 2535 void 2536 session_close_by_channel(int id, void *arg) 2537 { 2538 Session *s = session_by_channel(id); 2539 u_int i; 2540 2541 if (s == NULL) { 2542 debug("session_close_by_channel: no session for id %d", id); 2543 return; 2544 } 2545 debug("session_close_by_channel: channel %d child %ld", 2546 id, (long)s->pid); 2547 if (s->pid != 0) { 2548 debug("session_close_by_channel: channel %d: has child", id); 2549 /* 2550 * delay detach of session, but release pty, since 2551 * the fd's to the child are already closed 2552 */ 2553 if (s->ttyfd != -1) 2554 session_pty_cleanup(s); 2555 return; 2556 } 2557 /* detach by removing callback */ 2558 channel_cancel_cleanup(s->chanid); 2559 2560 /* Close any X11 listeners associated with this session */ 2561 if (s->x11_chanids != NULL) { 2562 for (i = 0; s->x11_chanids[i] != -1; i++) { 2563 session_close_x11(s->x11_chanids[i]); 2564 s->x11_chanids[i] = -1; 2565 } 2566 } 2567 2568 s->chanid = -1; 2569 session_close(s); 2570 } 2571 2572 void 2573 session_destroy_all(void (*closefunc)(Session *)) 2574 { 2575 int i; 2576 for (i = 0; i < sessions_nalloc; i++) { 2577 Session *s = &sessions[i]; 2578 if (s->used) { 2579 if (closefunc != NULL) 2580 closefunc(s); 2581 else 2582 session_close(s); 2583 } 2584 } 2585 } 2586 2587 static char * 2588 session_tty_list(void) 2589 { 2590 static char buf[1024]; 2591 int i; 2592 char *cp; 2593 2594 buf[0] = '\0'; 2595 for (i = 0; i < sessions_nalloc; i++) { 2596 Session *s = &sessions[i]; 2597 if (s->used && s->ttyfd != -1) { 2598 2599 if (strncmp(s->tty, "/dev/", 5) != 0) { 2600 cp = strrchr(s->tty, '/'); 2601 cp = (cp == NULL) ? s->tty : cp + 1; 2602 } else 2603 cp = s->tty + 5; 2604 2605 if (buf[0] != '\0') 2606 strlcat(buf, ",", sizeof buf); 2607 strlcat(buf, cp, sizeof buf); 2608 } 2609 } 2610 if (buf[0] == '\0') 2611 strlcpy(buf, "notty", sizeof buf); 2612 return buf; 2613 } 2614 2615 void 2616 session_proctitle(Session *s) 2617 { 2618 if (s->pw == NULL) 2619 error("no user for session %d", s->self); 2620 else 2621 setproctitle("%s@%s", s->pw->pw_name, session_tty_list()); 2622 } 2623 2624 int 2625 session_setup_x11fwd(Session *s) 2626 { 2627 struct stat st; 2628 char display[512], auth_display[512]; 2629 char hostname[MAXHOSTNAMELEN]; 2630 u_int i; 2631 2632 if (no_x11_forwarding_flag) { 2633 packet_send_debug("X11 forwarding disabled in user configuration file."); 2634 return 0; 2635 } 2636 if (!options.x11_forwarding) { 2637 debug("X11 forwarding disabled in server configuration file."); 2638 return 0; 2639 } 2640 if (!options.xauth_location || 2641 (stat(options.xauth_location, &st) == -1)) { 2642 packet_send_debug("No xauth program; cannot forward with spoofing."); 2643 return 0; 2644 } 2645 if (options.use_login) { 2646 packet_send_debug("X11 forwarding disabled; " 2647 "not compatible with UseLogin=yes."); 2648 return 0; 2649 } 2650 if (s->display != NULL) { 2651 debug("X11 display already set."); 2652 return 0; 2653 } 2654 if (x11_create_display_inet(options.x11_display_offset, 2655 options.x11_use_localhost, s->single_connection, 2656 &s->display_number, &s->x11_chanids) == -1) { 2657 debug("x11_create_display_inet failed."); 2658 return 0; 2659 } 2660 for (i = 0; s->x11_chanids[i] != -1; i++) { 2661 channel_register_cleanup(s->x11_chanids[i], 2662 session_close_single_x11, 0); 2663 } 2664 2665 /* Set up a suitable value for the DISPLAY variable. */ 2666 if (gethostname(hostname, sizeof(hostname)) < 0) 2667 fatal("gethostname: %.100s", strerror(errno)); 2668 /* 2669 * auth_display must be used as the displayname when the 2670 * authorization entry is added with xauth(1). This will be 2671 * different than the DISPLAY string for localhost displays. 2672 */ 2673 if (options.x11_use_localhost) { 2674 snprintf(display, sizeof display, "localhost:%u.%u", 2675 s->display_number, s->screen); 2676 snprintf(auth_display, sizeof auth_display, "unix:%u.%u", 2677 s->display_number, s->screen); 2678 s->display = xstrdup(display); 2679 s->auth_display = xstrdup(auth_display); 2680 } else { 2681 #ifdef IPADDR_IN_DISPLAY 2682 struct hostent *he; 2683 struct in_addr my_addr; 2684 2685 he = gethostbyname(hostname); 2686 if (he == NULL) { 2687 error("Can't get IP address for X11 DISPLAY."); 2688 packet_send_debug("Can't get IP address for X11 DISPLAY."); 2689 return 0; 2690 } 2691 memcpy(&my_addr, he->h_addr_list[0], sizeof(struct in_addr)); 2692 snprintf(display, sizeof display, "%.50s:%u.%u", inet_ntoa(my_addr), 2693 s->display_number, s->screen); 2694 #else 2695 snprintf(display, sizeof display, "%.400s:%u.%u", hostname, 2696 s->display_number, s->screen); 2697 #endif 2698 s->display = xstrdup(display); 2699 s->auth_display = xstrdup(display); 2700 } 2701 2702 return 1; 2703 } 2704 2705 static void 2706 do_authenticated2(Authctxt *authctxt) 2707 { 2708 server_loop2(authctxt); 2709 } 2710 2711 void 2712 do_cleanup(Authctxt *authctxt) 2713 { 2714 static int called = 0; 2715 2716 debug("do_cleanup"); 2717 2718 /* no cleanup if we're in the child for login shell */ 2719 if (is_child) 2720 return; 2721 2722 /* avoid double cleanup */ 2723 if (called) 2724 return; 2725 called = 1; 2726 2727 if (authctxt == NULL) 2728 return; 2729 2730 #ifdef USE_PAM 2731 if (options.use_pam) { 2732 sshpam_cleanup(); 2733 sshpam_thread_cleanup(); 2734 } 2735 #endif 2736 2737 if (!authctxt->authenticated) 2738 return; 2739 2740 #ifdef KRB5 2741 if (options.kerberos_ticket_cleanup && 2742 authctxt->krb5_ctx) 2743 krb5_cleanup_proc(authctxt); 2744 #endif 2745 2746 #ifdef GSSAPI 2747 if (compat20 && options.gss_cleanup_creds) 2748 ssh_gssapi_cleanup_creds(); 2749 #endif 2750 2751 /* remove agent socket */ 2752 auth_sock_cleanup_proc(authctxt->pw); 2753 2754 /* 2755 * Cleanup ptys/utmp only if privsep is disabled, 2756 * or if running in monitor. 2757 */ 2758 if (!use_privsep || mm_is_monitor()) 2759 session_destroy_all(session_pty_cleanup2); 2760 } 2761