1 /* $OpenBSD: session.c,v 1.258 2010/11/25 04:10:09 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 38 #include <sys/types.h> 39 #include <sys/param.h> 40 #ifdef HAVE_SYS_STAT_H 41 # include <sys/stat.h> 42 #endif 43 #include <sys/socket.h> 44 #include <sys/un.h> 45 #include <sys/wait.h> 46 47 #include <arpa/inet.h> 48 49 #include <errno.h> 50 #include <fcntl.h> 51 #include <grp.h> 52 #ifdef HAVE_PATHS_H 53 #include <paths.h> 54 #endif 55 #include <pwd.h> 56 #include <signal.h> 57 #include <stdarg.h> 58 #include <stdio.h> 59 #include <stdlib.h> 60 #include <string.h> 61 #include <unistd.h> 62 63 #include "openbsd-compat/sys-queue.h" 64 #include "xmalloc.h" 65 #include "ssh.h" 66 #include "ssh1.h" 67 #include "ssh2.h" 68 #include "sshpty.h" 69 #include "packet.h" 70 #include "buffer.h" 71 #include "match.h" 72 #include "uidswap.h" 73 #include "compat.h" 74 #include "channels.h" 75 #include "key.h" 76 #include "cipher.h" 77 #ifdef GSSAPI 78 #include "ssh-gss.h" 79 #endif 80 #include "hostfile.h" 81 #include "auth.h" 82 #include "auth-options.h" 83 #include "pathnames.h" 84 #include "log.h" 85 #include "servconf.h" 86 #include "sshlogin.h" 87 #include "serverloop.h" 88 #include "canohost.h" 89 #include "misc.h" 90 #include "session.h" 91 #include "kex.h" 92 #include "monitor_wrap.h" 93 #include "sftp.h" 94 95 #if defined(KRB5) && defined(USE_AFS) 96 #include <kafs.h> 97 #endif 98 99 #define IS_INTERNAL_SFTP(c) \ 100 (!strncmp(c, INTERNAL_SFTP_NAME, sizeof(INTERNAL_SFTP_NAME) - 1) && \ 101 (c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\0' || \ 102 c[sizeof(INTERNAL_SFTP_NAME) - 1] == ' ' || \ 103 c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\t')) 104 105 /* func */ 106 107 Session *session_new(void); 108 void session_set_fds(Session *, int, int, int, int, int); 109 void session_pty_cleanup(Session *); 110 void session_proctitle(Session *); 111 int session_setup_x11fwd(Session *); 112 int do_exec_pty(Session *, const char *); 113 int do_exec_no_pty(Session *, const char *); 114 int do_exec(Session *, const char *); 115 void do_login(Session *, const char *); 116 #ifdef LOGIN_NEEDS_UTMPX 117 static void do_pre_login(Session *s); 118 #endif 119 void do_child(Session *, const char *); 120 void do_motd(void); 121 int check_quietlogin(Session *, const char *); 122 123 static void do_authenticated1(Authctxt *); 124 static void do_authenticated2(Authctxt *); 125 126 static int session_pty_req(Session *); 127 128 /* import */ 129 extern ServerOptions options; 130 extern char *__progname; 131 extern int log_stderr; 132 extern int debug_flag; 133 extern u_int utmp_len; 134 extern int startup_pipe; 135 extern void destroy_sensitive_data(void); 136 extern Buffer loginmsg; 137 138 /* original command from peer. */ 139 const char *original_command = NULL; 140 141 /* data */ 142 static int sessions_first_unused = -1; 143 static int sessions_nalloc = 0; 144 static Session *sessions = NULL; 145 146 #define SUBSYSTEM_NONE 0 147 #define SUBSYSTEM_EXT 1 148 #define SUBSYSTEM_INT_SFTP 2 149 #define SUBSYSTEM_INT_SFTP_ERROR 3 150 151 #ifdef HAVE_LOGIN_CAP 152 login_cap_t *lc; 153 #endif 154 155 static int is_child = 0; 156 157 /* Name and directory of socket for authentication agent forwarding. */ 158 static char *auth_sock_name = NULL; 159 static char *auth_sock_dir = NULL; 160 161 /* removes the agent forwarding socket */ 162 163 static void 164 auth_sock_cleanup_proc(struct passwd *pw) 165 { 166 if (auth_sock_name != NULL) { 167 temporarily_use_uid(pw); 168 unlink(auth_sock_name); 169 rmdir(auth_sock_dir); 170 auth_sock_name = NULL; 171 restore_uid(); 172 } 173 } 174 175 static int 176 auth_input_request_forwarding(struct passwd * pw) 177 { 178 Channel *nc; 179 int sock = -1; 180 struct sockaddr_un sunaddr; 181 182 if (auth_sock_name != NULL) { 183 error("authentication forwarding requested twice."); 184 return 0; 185 } 186 187 /* Temporarily drop privileged uid for mkdir/bind. */ 188 temporarily_use_uid(pw); 189 190 /* Allocate a buffer for the socket name, and format the name. */ 191 auth_sock_dir = xstrdup("/tmp/ssh-XXXXXXXXXX"); 192 193 /* Create private directory for socket */ 194 if (mkdtemp(auth_sock_dir) == NULL) { 195 packet_send_debug("Agent forwarding disabled: " 196 "mkdtemp() failed: %.100s", strerror(errno)); 197 restore_uid(); 198 xfree(auth_sock_dir); 199 auth_sock_dir = NULL; 200 goto authsock_err; 201 } 202 203 xasprintf(&auth_sock_name, "%s/agent.%ld", 204 auth_sock_dir, (long) getpid()); 205 206 /* Create the socket. */ 207 sock = socket(AF_UNIX, SOCK_STREAM, 0); 208 if (sock < 0) { 209 error("socket: %.100s", strerror(errno)); 210 restore_uid(); 211 goto authsock_err; 212 } 213 214 /* Bind it to the name. */ 215 memset(&sunaddr, 0, sizeof(sunaddr)); 216 sunaddr.sun_family = AF_UNIX; 217 strlcpy(sunaddr.sun_path, auth_sock_name, sizeof(sunaddr.sun_path)); 218 219 if (bind(sock, (struct sockaddr *)&sunaddr, sizeof(sunaddr)) < 0) { 220 error("bind: %.100s", strerror(errno)); 221 restore_uid(); 222 goto authsock_err; 223 } 224 225 /* Restore the privileged uid. */ 226 restore_uid(); 227 228 /* Start listening on the socket. */ 229 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) { 230 error("listen: %.100s", strerror(errno)); 231 goto authsock_err; 232 } 233 234 /* Allocate a channel for the authentication agent socket. */ 235 /* this shouldn't matter if its hpn or not - cjr */ 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 options.ip_qos_interactive, options.ip_qos_bulk); 591 592 /* 593 * Clear loginmsg, since it's the child's responsibility to display 594 * it to the user, otherwise multiple sessions may accumulate 595 * multiple copies of the login messages. 596 */ 597 buffer_clear(&loginmsg); 598 599 #ifdef USE_PIPES 600 /* We are the parent. Close the child sides of the pipes. */ 601 close(pin[0]); 602 close(pout[1]); 603 close(perr[1]); 604 605 if (compat20) { 606 session_set_fds(s, pin[1], pout[0], perr[0], 607 s->is_subsystem, 0); 608 } else { 609 /* Enter the interactive session. */ 610 server_loop(pid, pin[1], pout[0], perr[0]); 611 /* server_loop has closed pin[1], pout[0], and perr[0]. */ 612 } 613 #else 614 /* We are the parent. Close the child sides of the socket pairs. */ 615 close(inout[0]); 616 close(err[0]); 617 618 /* 619 * Enter the interactive session. Note: server_loop must be able to 620 * handle the case that fdin and fdout are the same. 621 */ 622 if (compat20) { 623 session_set_fds(s, inout[1], inout[1], err[1], 624 s->is_subsystem, 0); 625 } else { 626 server_loop(pid, inout[1], inout[1], err[1]); 627 /* server_loop has closed inout[1] and err[1]. */ 628 } 629 #endif 630 return 0; 631 } 632 633 /* 634 * This is called to fork and execute a command when we have a tty. This 635 * will call do_child from the child, and server_loop from the parent after 636 * setting up file descriptors, controlling tty, updating wtmp, utmp, 637 * lastlog, and other such operations. 638 */ 639 int 640 do_exec_pty(Session *s, const char *command) 641 { 642 int fdout, ptyfd, ttyfd, ptymaster; 643 pid_t pid; 644 645 if (s == NULL) 646 fatal("do_exec_pty: no session"); 647 ptyfd = s->ptyfd; 648 ttyfd = s->ttyfd; 649 650 /* 651 * Create another descriptor of the pty master side for use as the 652 * standard input. We could use the original descriptor, but this 653 * simplifies code in server_loop. The descriptor is bidirectional. 654 * Do this before forking (and cleanup in the child) so as to 655 * detect and gracefully fail out-of-fd conditions. 656 */ 657 if ((fdout = dup(ptyfd)) < 0) { 658 error("%s: dup #1: %s", __func__, strerror(errno)); 659 close(ttyfd); 660 close(ptyfd); 661 return -1; 662 } 663 /* we keep a reference to the pty master */ 664 if ((ptymaster = dup(ptyfd)) < 0) { 665 error("%s: dup #2: %s", __func__, strerror(errno)); 666 close(ttyfd); 667 close(ptyfd); 668 close(fdout); 669 return -1; 670 } 671 672 /* Fork the child. */ 673 switch ((pid = fork())) { 674 case -1: 675 error("%s: fork: %.100s", __func__, strerror(errno)); 676 close(fdout); 677 close(ptymaster); 678 close(ttyfd); 679 close(ptyfd); 680 return -1; 681 case 0: 682 is_child = 1; 683 684 close(fdout); 685 close(ptymaster); 686 687 /* Child. Reinitialize the log because the pid has changed. */ 688 log_init(__progname, options.log_level, 689 options.log_facility, log_stderr); 690 /* Close the master side of the pseudo tty. */ 691 close(ptyfd); 692 693 /* Make the pseudo tty our controlling tty. */ 694 pty_make_controlling_tty(&ttyfd, s->tty); 695 696 /* Redirect stdin/stdout/stderr from the pseudo tty. */ 697 if (dup2(ttyfd, 0) < 0) 698 error("dup2 stdin: %s", strerror(errno)); 699 if (dup2(ttyfd, 1) < 0) 700 error("dup2 stdout: %s", strerror(errno)); 701 if (dup2(ttyfd, 2) < 0) 702 error("dup2 stderr: %s", strerror(errno)); 703 704 /* Close the extra descriptor for the pseudo tty. */ 705 close(ttyfd); 706 707 /* record login, etc. similar to login(1) */ 708 #ifndef HAVE_OSF_SIA 709 if (!(options.use_login && command == NULL)) { 710 #ifdef _UNICOS 711 cray_init_job(s->pw); /* set up cray jid and tmpdir */ 712 #endif /* _UNICOS */ 713 do_login(s, command); 714 } 715 # ifdef LOGIN_NEEDS_UTMPX 716 else 717 do_pre_login(s); 718 # endif 719 #endif 720 /* 721 * Do common processing for the child, such as execing 722 * the command. 723 */ 724 do_child(s, command); 725 /* NOTREACHED */ 726 default: 727 break; 728 } 729 730 #ifdef _UNICOS 731 signal(WJSIGNAL, cray_job_termination_handler); 732 #endif /* _UNICOS */ 733 #ifdef HAVE_CYGWIN 734 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); 735 #endif 736 737 s->pid = pid; 738 739 /* Parent. Close the slave side of the pseudo tty. */ 740 close(ttyfd); 741 742 /* Enter interactive session. */ 743 s->ptymaster = ptymaster; 744 packet_set_interactive(1, 745 options.ip_qos_interactive, options.ip_qos_bulk); 746 if (compat20) { 747 session_set_fds(s, ptyfd, fdout, -1, 1, 1); 748 } else { 749 server_loop(pid, ptyfd, fdout, -1); 750 /* server_loop _has_ closed ptyfd and fdout. */ 751 } 752 return 0; 753 } 754 755 #ifdef LOGIN_NEEDS_UTMPX 756 static void 757 do_pre_login(Session *s) 758 { 759 socklen_t fromlen; 760 struct sockaddr_storage from; 761 pid_t pid = getpid(); 762 763 /* 764 * Get IP address of client. If the connection is not a socket, let 765 * the address be 0.0.0.0. 766 */ 767 memset(&from, 0, sizeof(from)); 768 fromlen = sizeof(from); 769 if (packet_connection_is_on_socket()) { 770 if (getpeername(packet_get_connection_in(), 771 (struct sockaddr *)&from, &fromlen) < 0) { 772 debug("getpeername: %.100s", strerror(errno)); 773 cleanup_exit(255); 774 } 775 } 776 777 record_utmp_only(pid, s->tty, s->pw->pw_name, 778 get_remote_name_or_ip(utmp_len, options.use_dns), 779 (struct sockaddr *)&from, fromlen); 780 } 781 #endif 782 783 /* 784 * This is called to fork and execute a command. If another command is 785 * to be forced, execute that instead. 786 */ 787 int 788 do_exec(Session *s, const char *command) 789 { 790 int ret; 791 792 if (options.adm_forced_command) { 793 original_command = command; 794 command = options.adm_forced_command; 795 if (IS_INTERNAL_SFTP(command)) { 796 s->is_subsystem = s->is_subsystem ? 797 SUBSYSTEM_INT_SFTP : SUBSYSTEM_INT_SFTP_ERROR; 798 } else if (s->is_subsystem) 799 s->is_subsystem = SUBSYSTEM_EXT; 800 debug("Forced command (config) '%.900s'", command); 801 } else if (forced_command) { 802 original_command = command; 803 command = forced_command; 804 if (IS_INTERNAL_SFTP(command)) { 805 s->is_subsystem = s->is_subsystem ? 806 SUBSYSTEM_INT_SFTP : SUBSYSTEM_INT_SFTP_ERROR; 807 } else if (s->is_subsystem) 808 s->is_subsystem = SUBSYSTEM_EXT; 809 debug("Forced command (key option) '%.900s'", command); 810 } 811 812 #ifdef SSH_AUDIT_EVENTS 813 if (command != NULL) 814 PRIVSEP(audit_run_command(command)); 815 else if (s->ttyfd == -1) { 816 char *shell = s->pw->pw_shell; 817 818 if (shell[0] == '\0') /* empty shell means /bin/sh */ 819 shell =_PATH_BSHELL; 820 PRIVSEP(audit_run_command(shell)); 821 } 822 #endif 823 if (s->ttyfd != -1) 824 ret = do_exec_pty(s, command); 825 else 826 ret = do_exec_no_pty(s, command); 827 828 original_command = NULL; 829 830 /* 831 * Clear loginmsg: it's the child's responsibility to display 832 * it to the user, otherwise multiple sessions may accumulate 833 * multiple copies of the login messages. 834 */ 835 buffer_clear(&loginmsg); 836 837 return ret; 838 } 839 840 /* administrative, login(1)-like work */ 841 void 842 do_login(Session *s, const char *command) 843 { 844 socklen_t fromlen; 845 struct sockaddr_storage from; 846 struct passwd * pw = s->pw; 847 pid_t pid = getpid(); 848 849 /* 850 * Get IP address of client. If the connection is not a socket, let 851 * the address be 0.0.0.0. 852 */ 853 memset(&from, 0, sizeof(from)); 854 fromlen = sizeof(from); 855 if (packet_connection_is_on_socket()) { 856 if (getpeername(packet_get_connection_in(), 857 (struct sockaddr *)&from, &fromlen) < 0) { 858 debug("getpeername: %.100s", strerror(errno)); 859 cleanup_exit(255); 860 } 861 } 862 863 /* Record that there was a login on that tty from the remote host. */ 864 if (!use_privsep) 865 record_login(pid, s->tty, pw->pw_name, pw->pw_uid, 866 get_remote_name_or_ip(utmp_len, 867 options.use_dns), 868 (struct sockaddr *)&from, fromlen); 869 870 #ifdef USE_PAM 871 /* 872 * If password change is needed, do it now. 873 * This needs to occur before the ~/.hushlogin check. 874 */ 875 if (options.use_pam && !use_privsep && s->authctxt->force_pwchange) { 876 display_loginmsg(); 877 do_pam_chauthtok(); 878 s->authctxt->force_pwchange = 0; 879 /* XXX - signal [net] parent to enable forwardings */ 880 } 881 #endif 882 883 if (check_quietlogin(s, command)) 884 return; 885 886 display_loginmsg(); 887 888 do_motd(); 889 } 890 891 /* 892 * Display the message of the day. 893 */ 894 void 895 do_motd(void) 896 { 897 FILE *f; 898 char buf[256]; 899 #ifdef HAVE_LOGIN_CAP 900 const char *fname; 901 #endif 902 903 #ifdef HAVE_LOGIN_CAP 904 fname = login_getcapstr(lc, "copyright", NULL, NULL); 905 if (fname != NULL && (f = fopen(fname, "r")) != NULL) { 906 while (fgets(buf, sizeof(buf), f) != NULL) 907 fputs(buf, stdout); 908 fclose(f); 909 } else 910 #endif /* HAVE_LOGIN_CAP */ 911 (void)printf("%s\n\t%s %s\n", 912 "Copyright (c) 1980, 1983, 1986, 1988, 1990, 1991, 1993, 1994", 913 "The Regents of the University of California. ", 914 "All rights reserved."); 915 916 (void)printf("\n"); 917 918 if (options.print_motd) { 919 #ifdef HAVE_LOGIN_CAP 920 f = fopen(login_getcapstr(lc, "welcome", "/etc/motd", 921 "/etc/motd"), "r"); 922 #else 923 f = fopen("/etc/motd", "r"); 924 #endif 925 if (f) { 926 while (fgets(buf, sizeof(buf), f)) 927 fputs(buf, stdout); 928 fclose(f); 929 } 930 } 931 } 932 933 934 /* 935 * Check for quiet login, either .hushlogin or command given. 936 */ 937 int 938 check_quietlogin(Session *s, const char *command) 939 { 940 char buf[256]; 941 struct passwd *pw = s->pw; 942 struct stat st; 943 944 /* Return 1 if .hushlogin exists or a command given. */ 945 if (command != NULL) 946 return 1; 947 snprintf(buf, sizeof(buf), "%.200s/.hushlogin", pw->pw_dir); 948 #ifdef HAVE_LOGIN_CAP 949 if (login_getcapbool(lc, "hushlogin", 0) || stat(buf, &st) >= 0) 950 return 1; 951 #else 952 if (stat(buf, &st) >= 0) 953 return 1; 954 #endif 955 return 0; 956 } 957 958 /* 959 * Sets the value of the given variable in the environment. If the variable 960 * already exists, its value is overridden. 961 */ 962 void 963 child_set_env(char ***envp, u_int *envsizep, const char *name, 964 const char *value) 965 { 966 char **env; 967 u_int envsize; 968 u_int i, namelen; 969 970 /* 971 * If we're passed an uninitialized list, allocate a single null 972 * entry before continuing. 973 */ 974 if (*envp == NULL && *envsizep == 0) { 975 *envp = xmalloc(sizeof(char *)); 976 *envp[0] = NULL; 977 *envsizep = 1; 978 } 979 980 /* 981 * Find the slot where the value should be stored. If the variable 982 * already exists, we reuse the slot; otherwise we append a new slot 983 * at the end of the array, expanding if necessary. 984 */ 985 env = *envp; 986 namelen = strlen(name); 987 for (i = 0; env[i]; i++) 988 if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=') 989 break; 990 if (env[i]) { 991 /* Reuse the slot. */ 992 xfree(env[i]); 993 } else { 994 /* New variable. Expand if necessary. */ 995 envsize = *envsizep; 996 if (i >= envsize - 1) { 997 if (envsize >= 1000) 998 fatal("child_set_env: too many env vars"); 999 envsize += 50; 1000 env = (*envp) = xrealloc(env, envsize, sizeof(char *)); 1001 *envsizep = envsize; 1002 } 1003 /* Need to set the NULL pointer at end of array beyond the new slot. */ 1004 env[i + 1] = NULL; 1005 } 1006 1007 /* Allocate space and format the variable in the appropriate slot. */ 1008 env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1); 1009 snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value); 1010 } 1011 1012 /* 1013 * Reads environment variables from the given file and adds/overrides them 1014 * into the environment. If the file does not exist, this does nothing. 1015 * Otherwise, it must consist of empty lines, comments (line starts with '#') 1016 * and assignments of the form name=value. No other forms are allowed. 1017 */ 1018 static void 1019 read_environment_file(char ***env, u_int *envsize, 1020 const char *filename) 1021 { 1022 FILE *f; 1023 char buf[4096]; 1024 char *cp, *value; 1025 u_int lineno = 0; 1026 1027 f = fopen(filename, "r"); 1028 if (!f) 1029 return; 1030 1031 while (fgets(buf, sizeof(buf), f)) { 1032 if (++lineno > 1000) 1033 fatal("Too many lines in environment file %s", filename); 1034 for (cp = buf; *cp == ' ' || *cp == '\t'; cp++) 1035 ; 1036 if (!*cp || *cp == '#' || *cp == '\n') 1037 continue; 1038 1039 cp[strcspn(cp, "\n")] = '\0'; 1040 1041 value = strchr(cp, '='); 1042 if (value == NULL) { 1043 fprintf(stderr, "Bad line %u in %.100s\n", lineno, 1044 filename); 1045 continue; 1046 } 1047 /* 1048 * Replace the equals sign by nul, and advance value to 1049 * the value string. 1050 */ 1051 *value = '\0'; 1052 value++; 1053 child_set_env(env, envsize, cp, value); 1054 } 1055 fclose(f); 1056 } 1057 1058 #ifdef HAVE_ETC_DEFAULT_LOGIN 1059 /* 1060 * Return named variable from specified environment, or NULL if not present. 1061 */ 1062 static char * 1063 child_get_env(char **env, const char *name) 1064 { 1065 int i; 1066 size_t len; 1067 1068 len = strlen(name); 1069 for (i=0; env[i] != NULL; i++) 1070 if (strncmp(name, env[i], len) == 0 && env[i][len] == '=') 1071 return(env[i] + len + 1); 1072 return NULL; 1073 } 1074 1075 /* 1076 * Read /etc/default/login. 1077 * We pick up the PATH (or SUPATH for root) and UMASK. 1078 */ 1079 static void 1080 read_etc_default_login(char ***env, u_int *envsize, uid_t uid) 1081 { 1082 char **tmpenv = NULL, *var; 1083 u_int i, tmpenvsize = 0; 1084 u_long mask; 1085 1086 /* 1087 * We don't want to copy the whole file to the child's environment, 1088 * so we use a temporary environment and copy the variables we're 1089 * interested in. 1090 */ 1091 read_environment_file(&tmpenv, &tmpenvsize, "/etc/default/login"); 1092 1093 if (tmpenv == NULL) 1094 return; 1095 1096 if (uid == 0) 1097 var = child_get_env(tmpenv, "SUPATH"); 1098 else 1099 var = child_get_env(tmpenv, "PATH"); 1100 if (var != NULL) 1101 child_set_env(env, envsize, "PATH", var); 1102 1103 if ((var = child_get_env(tmpenv, "UMASK")) != NULL) 1104 if (sscanf(var, "%5lo", &mask) == 1) 1105 umask((mode_t)mask); 1106 1107 for (i = 0; tmpenv[i] != NULL; i++) 1108 xfree(tmpenv[i]); 1109 xfree(tmpenv); 1110 } 1111 #endif /* HAVE_ETC_DEFAULT_LOGIN */ 1112 1113 void 1114 copy_environment(char **source, char ***env, u_int *envsize) 1115 { 1116 char *var_name, *var_val; 1117 int i; 1118 1119 if (source == NULL) 1120 return; 1121 1122 for(i = 0; source[i] != NULL; i++) { 1123 var_name = xstrdup(source[i]); 1124 if ((var_val = strstr(var_name, "=")) == NULL) { 1125 xfree(var_name); 1126 continue; 1127 } 1128 *var_val++ = '\0'; 1129 1130 debug3("Copy environment: %s=%s", var_name, var_val); 1131 child_set_env(env, envsize, var_name, var_val); 1132 1133 xfree(var_name); 1134 } 1135 } 1136 1137 static char ** 1138 do_setup_env(Session *s, const char *shell) 1139 { 1140 char buf[256]; 1141 u_int i, envsize; 1142 char **env, *laddr; 1143 struct passwd *pw = s->pw; 1144 #if !defined (HAVE_LOGIN_CAP) && !defined (HAVE_CYGWIN) 1145 char *path = NULL; 1146 #else 1147 extern char **environ; 1148 char **senv; 1149 #if 0 1150 char **var; 1151 #endif 1152 #endif 1153 1154 /* Initialize the environment. */ 1155 envsize = 100; 1156 env = xcalloc(envsize, sizeof(char *)); 1157 env[0] = NULL; 1158 1159 #ifdef HAVE_CYGWIN 1160 /* 1161 * The Windows environment contains some setting which are 1162 * important for a running system. They must not be dropped. 1163 */ 1164 { 1165 char **p; 1166 1167 p = fetch_windows_environment(); 1168 copy_environment(p, &env, &envsize); 1169 free_windows_environment(p); 1170 } 1171 #endif 1172 1173 if (getenv("TZ")) 1174 child_set_env(&env, &envsize, "TZ", getenv("TZ")); 1175 1176 #ifdef GSSAPI 1177 /* Allow any GSSAPI methods that we've used to alter 1178 * the childs environment as they see fit 1179 */ 1180 ssh_gssapi_do_child(&env, &envsize); 1181 #endif 1182 1183 if (!options.use_login) { 1184 /* Set basic environment. */ 1185 for (i = 0; i < s->num_env; i++) 1186 child_set_env(&env, &envsize, s->env[i].name, 1187 s->env[i].val); 1188 1189 child_set_env(&env, &envsize, "USER", pw->pw_name); 1190 child_set_env(&env, &envsize, "LOGNAME", pw->pw_name); 1191 #ifdef _AIX 1192 child_set_env(&env, &envsize, "LOGIN", pw->pw_name); 1193 #endif 1194 child_set_env(&env, &envsize, "HOME", pw->pw_dir); 1195 snprintf(buf, sizeof buf, "%.200s/%.50s", 1196 _PATH_MAILDIR, pw->pw_name); 1197 child_set_env(&env, &envsize, "MAIL", buf); 1198 #ifdef HAVE_LOGIN_CAP 1199 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); 1200 child_set_env(&env, &envsize, "TERM", "su"); 1201 senv = environ; 1202 environ = xmalloc(sizeof(char *)); 1203 *environ = NULL; 1204 (void) setusercontext(lc, pw, pw->pw_uid, 1205 LOGIN_SETENV|LOGIN_SETPATH); 1206 copy_environment(environ, &env, &envsize); 1207 #if 0 1208 /* 1209 * This interferes with libc's management of the environment 1210 * in horrible ways that can cause sshd to crash. 1211 */ 1212 for (var = environ; *var != NULL; ++var) 1213 xfree(*var); 1214 xfree(environ); 1215 #endif 1216 environ = senv; 1217 #else /* HAVE_LOGIN_CAP */ 1218 # ifndef HAVE_CYGWIN 1219 /* 1220 * There's no standard path on Windows. The path contains 1221 * important components pointing to the system directories, 1222 * needed for loading shared libraries. So the path better 1223 * remains intact here. 1224 */ 1225 # ifdef HAVE_ETC_DEFAULT_LOGIN 1226 read_etc_default_login(&env, &envsize, pw->pw_uid); 1227 path = child_get_env(env, "PATH"); 1228 # endif /* HAVE_ETC_DEFAULT_LOGIN */ 1229 if (path == NULL || *path == '\0') { 1230 child_set_env(&env, &envsize, "PATH", 1231 s->pw->pw_uid == 0 ? 1232 SUPERUSER_PATH : _PATH_STDPATH); 1233 } 1234 # endif /* HAVE_CYGWIN */ 1235 #endif /* HAVE_LOGIN_CAP */ 1236 1237 /* Normal systems set SHELL by default. */ 1238 child_set_env(&env, &envsize, "SHELL", shell); 1239 } 1240 1241 /* Set custom environment options from RSA authentication. */ 1242 if (!options.use_login) { 1243 while (custom_environment) { 1244 struct envstring *ce = custom_environment; 1245 char *str = ce->s; 1246 1247 for (i = 0; str[i] != '=' && str[i]; i++) 1248 ; 1249 if (str[i] == '=') { 1250 str[i] = 0; 1251 child_set_env(&env, &envsize, str, str + i + 1); 1252 } 1253 custom_environment = ce->next; 1254 xfree(ce->s); 1255 xfree(ce); 1256 } 1257 } 1258 1259 /* SSH_CLIENT deprecated */ 1260 snprintf(buf, sizeof buf, "%.50s %d %d", 1261 get_remote_ipaddr(), get_remote_port(), get_local_port()); 1262 child_set_env(&env, &envsize, "SSH_CLIENT", buf); 1263 1264 laddr = get_local_ipaddr(packet_get_connection_in()); 1265 snprintf(buf, sizeof buf, "%.50s %d %.50s %d", 1266 get_remote_ipaddr(), get_remote_port(), laddr, get_local_port()); 1267 xfree(laddr); 1268 child_set_env(&env, &envsize, "SSH_CONNECTION", buf); 1269 1270 if (s->ttyfd != -1) 1271 child_set_env(&env, &envsize, "SSH_TTY", s->tty); 1272 if (s->term) 1273 child_set_env(&env, &envsize, "TERM", s->term); 1274 if (s->display) 1275 child_set_env(&env, &envsize, "DISPLAY", s->display); 1276 if (original_command) 1277 child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND", 1278 original_command); 1279 1280 #ifdef _UNICOS 1281 if (cray_tmpdir[0] != '\0') 1282 child_set_env(&env, &envsize, "TMPDIR", cray_tmpdir); 1283 #endif /* _UNICOS */ 1284 1285 /* 1286 * Since we clear KRB5CCNAME at startup, if it's set now then it 1287 * must have been set by a native authentication method (eg AIX or 1288 * SIA), so copy it to the child. 1289 */ 1290 { 1291 char *cp; 1292 1293 if ((cp = getenv("KRB5CCNAME")) != NULL) 1294 child_set_env(&env, &envsize, "KRB5CCNAME", cp); 1295 } 1296 1297 #ifdef _AIX 1298 { 1299 char *cp; 1300 1301 if ((cp = getenv("AUTHSTATE")) != NULL) 1302 child_set_env(&env, &envsize, "AUTHSTATE", cp); 1303 read_environment_file(&env, &envsize, "/etc/environment"); 1304 } 1305 #endif 1306 #ifdef KRB5 1307 if (s->authctxt->krb5_ccname) 1308 child_set_env(&env, &envsize, "KRB5CCNAME", 1309 s->authctxt->krb5_ccname); 1310 #endif 1311 #ifdef USE_PAM 1312 /* 1313 * Pull in any environment variables that may have 1314 * been set by PAM. 1315 */ 1316 if (options.use_pam) { 1317 char **p; 1318 1319 p = fetch_pam_child_environment(); 1320 copy_environment(p, &env, &envsize); 1321 free_pam_environment(p); 1322 1323 p = fetch_pam_environment(); 1324 copy_environment(p, &env, &envsize); 1325 free_pam_environment(p); 1326 } 1327 #endif /* USE_PAM */ 1328 1329 if (auth_sock_name != NULL) 1330 child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME, 1331 auth_sock_name); 1332 1333 /* read $HOME/.ssh/environment. */ 1334 if (options.permit_user_env && !options.use_login) { 1335 snprintf(buf, sizeof buf, "%.200s/.ssh/environment", 1336 strcmp(pw->pw_dir, "/") ? pw->pw_dir : ""); 1337 read_environment_file(&env, &envsize, buf); 1338 } 1339 if (debug_flag) { 1340 /* dump the environment */ 1341 fprintf(stderr, "Environment:\n"); 1342 for (i = 0; env[i]; i++) 1343 fprintf(stderr, " %.200s\n", env[i]); 1344 } 1345 return env; 1346 } 1347 1348 /* 1349 * Run $HOME/.ssh/rc, /etc/ssh/sshrc, or xauth (whichever is found 1350 * first in this order). 1351 */ 1352 static void 1353 do_rc_files(Session *s, const char *shell) 1354 { 1355 FILE *f = NULL; 1356 char cmd[1024]; 1357 int do_xauth; 1358 struct stat st; 1359 1360 do_xauth = 1361 s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL; 1362 1363 /* ignore _PATH_SSH_USER_RC for subsystems and admin forced commands */ 1364 if (!s->is_subsystem && options.adm_forced_command == NULL && 1365 !no_user_rc && stat(_PATH_SSH_USER_RC, &st) >= 0) { 1366 snprintf(cmd, sizeof cmd, "%s -c '%s %s'", 1367 shell, _PATH_BSHELL, _PATH_SSH_USER_RC); 1368 if (debug_flag) 1369 fprintf(stderr, "Running %s\n", cmd); 1370 f = popen(cmd, "w"); 1371 if (f) { 1372 if (do_xauth) 1373 fprintf(f, "%s %s\n", s->auth_proto, 1374 s->auth_data); 1375 pclose(f); 1376 } else 1377 fprintf(stderr, "Could not run %s\n", 1378 _PATH_SSH_USER_RC); 1379 } else if (stat(_PATH_SSH_SYSTEM_RC, &st) >= 0) { 1380 if (debug_flag) 1381 fprintf(stderr, "Running %s %s\n", _PATH_BSHELL, 1382 _PATH_SSH_SYSTEM_RC); 1383 f = popen(_PATH_BSHELL " " _PATH_SSH_SYSTEM_RC, "w"); 1384 if (f) { 1385 if (do_xauth) 1386 fprintf(f, "%s %s\n", s->auth_proto, 1387 s->auth_data); 1388 pclose(f); 1389 } else 1390 fprintf(stderr, "Could not run %s\n", 1391 _PATH_SSH_SYSTEM_RC); 1392 } else if (do_xauth && options.xauth_location != NULL) { 1393 /* Add authority data to .Xauthority if appropriate. */ 1394 if (debug_flag) { 1395 fprintf(stderr, 1396 "Running %.500s remove %.100s\n", 1397 options.xauth_location, s->auth_display); 1398 fprintf(stderr, 1399 "%.500s add %.100s %.100s %.100s\n", 1400 options.xauth_location, s->auth_display, 1401 s->auth_proto, s->auth_data); 1402 } 1403 snprintf(cmd, sizeof cmd, "%s -q -", 1404 options.xauth_location); 1405 f = popen(cmd, "w"); 1406 if (f) { 1407 fprintf(f, "remove %s\n", 1408 s->auth_display); 1409 fprintf(f, "add %s %s %s\n", 1410 s->auth_display, s->auth_proto, 1411 s->auth_data); 1412 pclose(f); 1413 } else { 1414 fprintf(stderr, "Could not run %s\n", 1415 cmd); 1416 } 1417 } 1418 } 1419 1420 static void 1421 do_nologin(struct passwd *pw) 1422 { 1423 FILE *f = NULL; 1424 char buf[1024], *nl, *def_nl = _PATH_NOLOGIN; 1425 struct stat sb; 1426 1427 #ifdef HAVE_LOGIN_CAP 1428 if (login_getcapbool(lc, "ignorenologin", 0) && pw->pw_uid) 1429 return; 1430 nl = login_getcapstr(lc, "nologin", def_nl, def_nl); 1431 #else 1432 if (pw->pw_uid == 0) 1433 return; 1434 nl = def_nl; 1435 #endif 1436 if (stat(nl, &sb) == -1) { 1437 if (nl != def_nl) 1438 xfree(nl); 1439 return; 1440 } 1441 1442 /* /etc/nologin exists. Print its contents if we can and exit. */ 1443 logit("User %.100s not allowed because %s exists", pw->pw_name, nl); 1444 if ((f = fopen(nl, "r")) != NULL) { 1445 while (fgets(buf, sizeof(buf), f)) 1446 fputs(buf, stderr); 1447 fclose(f); 1448 } 1449 exit(254); 1450 } 1451 1452 /* 1453 * Chroot into a directory after checking it for safety: all path components 1454 * must be root-owned directories with strict permissions. 1455 */ 1456 static void 1457 safely_chroot(const char *path, uid_t uid) 1458 { 1459 const char *cp; 1460 char component[MAXPATHLEN]; 1461 struct stat st; 1462 1463 if (*path != '/') 1464 fatal("chroot path does not begin at root"); 1465 if (strlen(path) >= sizeof(component)) 1466 fatal("chroot path too long"); 1467 1468 /* 1469 * Descend the path, checking that each component is a 1470 * root-owned directory with strict permissions. 1471 */ 1472 for (cp = path; cp != NULL;) { 1473 if ((cp = strchr(cp, '/')) == NULL) 1474 strlcpy(component, path, sizeof(component)); 1475 else { 1476 cp++; 1477 memcpy(component, path, cp - path); 1478 component[cp - path] = '\0'; 1479 } 1480 1481 debug3("%s: checking '%s'", __func__, component); 1482 1483 if (stat(component, &st) != 0) 1484 fatal("%s: stat(\"%s\"): %s", __func__, 1485 component, strerror(errno)); 1486 if (st.st_uid != 0 || (st.st_mode & 022) != 0) 1487 fatal("bad ownership or modes for chroot " 1488 "directory %s\"%s\"", 1489 cp == NULL ? "" : "component ", component); 1490 if (!S_ISDIR(st.st_mode)) 1491 fatal("chroot path %s\"%s\" is not a directory", 1492 cp == NULL ? "" : "component ", component); 1493 1494 } 1495 1496 if (chdir(path) == -1) 1497 fatal("Unable to chdir to chroot path \"%s\": " 1498 "%s", path, strerror(errno)); 1499 if (chroot(path) == -1) 1500 fatal("chroot(\"%s\"): %s", path, strerror(errno)); 1501 if (chdir("/") == -1) 1502 fatal("%s: chdir(/) after chroot: %s", 1503 __func__, strerror(errno)); 1504 verbose("Changed root directory to \"%s\"", path); 1505 } 1506 1507 /* Set login name, uid, gid, and groups. */ 1508 void 1509 do_setusercontext(struct passwd *pw) 1510 { 1511 char *chroot_path, *tmp; 1512 1513 platform_setusercontext(pw); 1514 1515 if (platform_privileged_uidswap()) { 1516 #ifdef HAVE_LOGIN_CAP 1517 if (setusercontext(lc, pw, pw->pw_uid, 1518 (LOGIN_SETALL & ~(LOGIN_SETPATH|LOGIN_SETUSER))) < 0) { 1519 perror("unable to set user context"); 1520 exit(1); 1521 } 1522 #else 1523 if (setlogin(pw->pw_name) < 0) 1524 error("setlogin failed: %s", strerror(errno)); 1525 if (setgid(pw->pw_gid) < 0) { 1526 perror("setgid"); 1527 exit(1); 1528 } 1529 /* Initialize the group list. */ 1530 if (initgroups(pw->pw_name, pw->pw_gid) < 0) { 1531 perror("initgroups"); 1532 exit(1); 1533 } 1534 endgrent(); 1535 #endif 1536 1537 platform_setusercontext_post_groups(pw); 1538 1539 if (options.chroot_directory != NULL && 1540 strcasecmp(options.chroot_directory, "none") != 0) { 1541 tmp = tilde_expand_filename(options.chroot_directory, 1542 pw->pw_uid); 1543 chroot_path = percent_expand(tmp, "h", pw->pw_dir, 1544 "u", pw->pw_name, (char *)NULL); 1545 safely_chroot(chroot_path, pw->pw_uid); 1546 free(tmp); 1547 free(chroot_path); 1548 } 1549 1550 #ifdef HAVE_LOGIN_CAP 1551 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUSER) < 0) { 1552 perror("unable to set user context (setuser)"); 1553 exit(1); 1554 } 1555 #else 1556 /* Permanently switch to the desired uid. */ 1557 permanently_set_uid(pw); 1558 #endif 1559 } 1560 1561 if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) 1562 fatal("Failed to set uids to %u.", (u_int) pw->pw_uid); 1563 } 1564 1565 static void 1566 do_pwchange(Session *s) 1567 { 1568 fflush(NULL); 1569 fprintf(stderr, "WARNING: Your password has expired.\n"); 1570 if (s->ttyfd != -1) { 1571 fprintf(stderr, 1572 "You must change your password now and login again!\n"); 1573 #ifdef PASSWD_NEEDS_USERNAME 1574 execl(_PATH_PASSWD_PROG, "passwd", s->pw->pw_name, 1575 (char *)NULL); 1576 #else 1577 execl(_PATH_PASSWD_PROG, "passwd", (char *)NULL); 1578 #endif 1579 perror("passwd"); 1580 } else { 1581 fprintf(stderr, 1582 "Password change required but no TTY available.\n"); 1583 } 1584 exit(1); 1585 } 1586 1587 static void 1588 launch_login(struct passwd *pw, const char *hostname) 1589 { 1590 /* Launch login(1). */ 1591 1592 execl(LOGIN_PROGRAM, "login", "-h", hostname, 1593 #ifdef xxxLOGIN_NEEDS_TERM 1594 (s->term ? s->term : "unknown"), 1595 #endif /* LOGIN_NEEDS_TERM */ 1596 #ifdef LOGIN_NO_ENDOPT 1597 "-p", "-f", pw->pw_name, (char *)NULL); 1598 #else 1599 "-p", "-f", "--", pw->pw_name, (char *)NULL); 1600 #endif 1601 1602 /* Login couldn't be executed, die. */ 1603 1604 perror("login"); 1605 exit(1); 1606 } 1607 1608 static void 1609 child_close_fds(void) 1610 { 1611 if (packet_get_connection_in() == packet_get_connection_out()) 1612 close(packet_get_connection_in()); 1613 else { 1614 close(packet_get_connection_in()); 1615 close(packet_get_connection_out()); 1616 } 1617 /* 1618 * Close all descriptors related to channels. They will still remain 1619 * open in the parent. 1620 */ 1621 /* XXX better use close-on-exec? -markus */ 1622 channel_close_all(); 1623 1624 /* 1625 * Close any extra file descriptors. Note that there may still be 1626 * descriptors left by system functions. They will be closed later. 1627 */ 1628 endpwent(); 1629 1630 /* 1631 * Close any extra open file descriptors so that we don't have them 1632 * hanging around in clients. Note that we want to do this after 1633 * initgroups, because at least on Solaris 2.3 it leaves file 1634 * descriptors open. 1635 */ 1636 closefrom(STDERR_FILENO + 1); 1637 } 1638 1639 /* 1640 * Performs common processing for the child, such as setting up the 1641 * environment, closing extra file descriptors, setting the user and group 1642 * ids, and executing the command or shell. 1643 */ 1644 #define ARGV_MAX 10 1645 void 1646 do_child(Session *s, const char *command) 1647 { 1648 extern char **environ; 1649 char **env; 1650 char *argv[ARGV_MAX]; 1651 const char *shell, *shell0, *hostname = NULL; 1652 struct passwd *pw = s->pw; 1653 int r = 0; 1654 1655 /* remove hostkey from the child's memory */ 1656 destroy_sensitive_data(); 1657 1658 /* Force a password change */ 1659 if (s->authctxt->force_pwchange) { 1660 do_setusercontext(pw); 1661 child_close_fds(); 1662 do_pwchange(s); 1663 exit(1); 1664 } 1665 1666 /* login(1) is only called if we execute the login shell */ 1667 if (options.use_login && command != NULL) 1668 options.use_login = 0; 1669 1670 #ifdef _UNICOS 1671 cray_setup(pw->pw_uid, pw->pw_name, command); 1672 #endif /* _UNICOS */ 1673 1674 /* 1675 * Login(1) does this as well, and it needs uid 0 for the "-h" 1676 * switch, so we let login(1) to this for us. 1677 */ 1678 if (!options.use_login) { 1679 #ifdef HAVE_OSF_SIA 1680 session_setup_sia(pw, s->ttyfd == -1 ? NULL : s->tty); 1681 if (!check_quietlogin(s, command)) 1682 do_motd(); 1683 #else /* HAVE_OSF_SIA */ 1684 /* When PAM is enabled we rely on it to do the nologin check */ 1685 if (!options.use_pam) 1686 do_nologin(pw); 1687 do_setusercontext(pw); 1688 /* 1689 * PAM session modules in do_setusercontext may have 1690 * generated messages, so if this in an interactive 1691 * login then display them too. 1692 */ 1693 if (!check_quietlogin(s, command)) 1694 display_loginmsg(); 1695 #endif /* HAVE_OSF_SIA */ 1696 } 1697 1698 #ifdef USE_PAM 1699 if (options.use_pam && !options.use_login && !is_pam_session_open()) { 1700 debug3("PAM session not opened, exiting"); 1701 display_loginmsg(); 1702 exit(254); 1703 } 1704 #endif 1705 1706 /* 1707 * Get the shell from the password data. An empty shell field is 1708 * legal, and means /bin/sh. 1709 */ 1710 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; 1711 1712 /* 1713 * Make sure $SHELL points to the shell from the password file, 1714 * even if shell is overridden from login.conf 1715 */ 1716 env = do_setup_env(s, shell); 1717 1718 #ifdef HAVE_LOGIN_CAP 1719 shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell); 1720 #endif 1721 1722 /* we have to stash the hostname before we close our socket. */ 1723 if (options.use_login) 1724 hostname = get_remote_name_or_ip(utmp_len, 1725 options.use_dns); 1726 /* 1727 * Close the connection descriptors; note that this is the child, and 1728 * the server will still have the socket open, and it is important 1729 * that we do not shutdown it. Note that the descriptors cannot be 1730 * closed before building the environment, as we call 1731 * get_remote_ipaddr there. 1732 */ 1733 child_close_fds(); 1734 1735 /* 1736 * Must take new environment into use so that .ssh/rc, 1737 * /etc/ssh/sshrc and xauth are run in the proper environment. 1738 */ 1739 environ = env; 1740 1741 #if defined(KRB5) && defined(USE_AFS) 1742 /* 1743 * At this point, we check to see if AFS is active and if we have 1744 * a valid Kerberos 5 TGT. If so, it seems like a good idea to see 1745 * if we can (and need to) extend the ticket into an AFS token. If 1746 * we don't do this, we run into potential problems if the user's 1747 * home directory is in AFS and it's not world-readable. 1748 */ 1749 1750 if (options.kerberos_get_afs_token && k_hasafs() && 1751 (s->authctxt->krb5_ctx != NULL)) { 1752 char cell[64]; 1753 1754 debug("Getting AFS token"); 1755 1756 k_setpag(); 1757 1758 if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0) 1759 krb5_afslog(s->authctxt->krb5_ctx, 1760 s->authctxt->krb5_fwd_ccache, cell, NULL); 1761 1762 krb5_afslog_home(s->authctxt->krb5_ctx, 1763 s->authctxt->krb5_fwd_ccache, NULL, NULL, pw->pw_dir); 1764 } 1765 #endif 1766 1767 /* Change current directory to the user's home directory. */ 1768 if (chdir(pw->pw_dir) < 0) { 1769 /* Suppress missing homedir warning for chroot case */ 1770 #ifdef HAVE_LOGIN_CAP 1771 r = login_getcapbool(lc, "requirehome", 0); 1772 #endif 1773 if (r || options.chroot_directory == NULL || 1774 strcasecmp(options.chroot_directory, "none") == 0) 1775 fprintf(stderr, "Could not chdir to home " 1776 "directory %s: %s\n", pw->pw_dir, 1777 strerror(errno)); 1778 if (r) 1779 exit(1); 1780 } 1781 1782 closefrom(STDERR_FILENO + 1); 1783 1784 if (!options.use_login) 1785 do_rc_files(s, shell); 1786 1787 /* restore SIGPIPE for child */ 1788 signal(SIGPIPE, SIG_DFL); 1789 1790 if (s->is_subsystem == SUBSYSTEM_INT_SFTP_ERROR) { 1791 printf("This service allows sftp connections only.\n"); 1792 fflush(NULL); 1793 exit(1); 1794 } else if (s->is_subsystem == SUBSYSTEM_INT_SFTP) { 1795 extern int optind, optreset; 1796 int i; 1797 char *p, *args; 1798 1799 setproctitle("%s@%s", s->pw->pw_name, INTERNAL_SFTP_NAME); 1800 args = xstrdup(command ? command : "sftp-server"); 1801 for (i = 0, (p = strtok(args, " ")); p; (p = strtok(NULL, " "))) 1802 if (i < ARGV_MAX - 1) 1803 argv[i++] = p; 1804 argv[i] = NULL; 1805 optind = optreset = 1; 1806 __progname = argv[0]; 1807 #ifdef WITH_SELINUX 1808 ssh_selinux_change_context("sftpd_t"); 1809 #endif 1810 exit(sftp_server_main(i, argv, s->pw)); 1811 } 1812 1813 fflush(NULL); 1814 1815 if (options.use_login) { 1816 launch_login(pw, hostname); 1817 /* NEVERREACHED */ 1818 } 1819 1820 /* Get the last component of the shell name. */ 1821 if ((shell0 = strrchr(shell, '/')) != NULL) 1822 shell0++; 1823 else 1824 shell0 = shell; 1825 1826 /* 1827 * If we have no command, execute the shell. In this case, the shell 1828 * name to be passed in argv[0] is preceded by '-' to indicate that 1829 * this is a login shell. 1830 */ 1831 if (!command) { 1832 char argv0[256]; 1833 1834 /* Start the shell. Set initial character to '-'. */ 1835 argv0[0] = '-'; 1836 1837 if (strlcpy(argv0 + 1, shell0, sizeof(argv0) - 1) 1838 >= sizeof(argv0) - 1) { 1839 errno = EINVAL; 1840 perror(shell); 1841 exit(1); 1842 } 1843 1844 /* Execute the shell. */ 1845 argv[0] = argv0; 1846 argv[1] = NULL; 1847 execve(shell, argv, env); 1848 1849 /* Executing the shell failed. */ 1850 perror(shell); 1851 exit(1); 1852 } 1853 /* 1854 * Execute the command using the user's shell. This uses the -c 1855 * option to execute the command. 1856 */ 1857 argv[0] = (char *) shell0; 1858 argv[1] = "-c"; 1859 argv[2] = (char *) command; 1860 argv[3] = NULL; 1861 execve(shell, argv, env); 1862 perror(shell); 1863 exit(1); 1864 } 1865 1866 void 1867 session_unused(int id) 1868 { 1869 debug3("%s: session id %d unused", __func__, id); 1870 if (id >= options.max_sessions || 1871 id >= sessions_nalloc) { 1872 fatal("%s: insane session id %d (max %d nalloc %d)", 1873 __func__, id, options.max_sessions, sessions_nalloc); 1874 } 1875 bzero(&sessions[id], sizeof(*sessions)); 1876 sessions[id].self = id; 1877 sessions[id].used = 0; 1878 sessions[id].chanid = -1; 1879 sessions[id].ptyfd = -1; 1880 sessions[id].ttyfd = -1; 1881 sessions[id].ptymaster = -1; 1882 sessions[id].x11_chanids = NULL; 1883 sessions[id].next_unused = sessions_first_unused; 1884 sessions_first_unused = id; 1885 } 1886 1887 Session * 1888 session_new(void) 1889 { 1890 Session *s, *tmp; 1891 1892 if (sessions_first_unused == -1) { 1893 if (sessions_nalloc >= options.max_sessions) 1894 return NULL; 1895 debug2("%s: allocate (allocated %d max %d)", 1896 __func__, sessions_nalloc, options.max_sessions); 1897 tmp = xrealloc(sessions, sessions_nalloc + 1, 1898 sizeof(*sessions)); 1899 if (tmp == NULL) { 1900 error("%s: cannot allocate %d sessions", 1901 __func__, sessions_nalloc + 1); 1902 return NULL; 1903 } 1904 sessions = tmp; 1905 session_unused(sessions_nalloc++); 1906 } 1907 1908 if (sessions_first_unused >= sessions_nalloc || 1909 sessions_first_unused < 0) { 1910 fatal("%s: insane first_unused %d max %d nalloc %d", 1911 __func__, sessions_first_unused, options.max_sessions, 1912 sessions_nalloc); 1913 } 1914 1915 s = &sessions[sessions_first_unused]; 1916 if (s->used) { 1917 fatal("%s: session %d already used", 1918 __func__, sessions_first_unused); 1919 } 1920 sessions_first_unused = s->next_unused; 1921 s->used = 1; 1922 s->next_unused = -1; 1923 debug("session_new: session %d", s->self); 1924 1925 return s; 1926 } 1927 1928 static void 1929 session_dump(void) 1930 { 1931 int i; 1932 for (i = 0; i < sessions_nalloc; i++) { 1933 Session *s = &sessions[i]; 1934 1935 debug("dump: used %d next_unused %d session %d %p " 1936 "channel %d pid %ld", 1937 s->used, 1938 s->next_unused, 1939 s->self, 1940 s, 1941 s->chanid, 1942 (long)s->pid); 1943 } 1944 } 1945 1946 int 1947 session_open(Authctxt *authctxt, int chanid) 1948 { 1949 Session *s = session_new(); 1950 debug("session_open: channel %d", chanid); 1951 if (s == NULL) { 1952 error("no more sessions"); 1953 return 0; 1954 } 1955 s->authctxt = authctxt; 1956 s->pw = authctxt->pw; 1957 if (s->pw == NULL || !authctxt->valid) 1958 fatal("no user for session %d", s->self); 1959 debug("session_open: session %d: link with channel %d", s->self, chanid); 1960 s->chanid = chanid; 1961 return 1; 1962 } 1963 1964 Session * 1965 session_by_tty(char *tty) 1966 { 1967 int i; 1968 for (i = 0; i < sessions_nalloc; i++) { 1969 Session *s = &sessions[i]; 1970 if (s->used && s->ttyfd != -1 && strcmp(s->tty, tty) == 0) { 1971 debug("session_by_tty: session %d tty %s", i, tty); 1972 return s; 1973 } 1974 } 1975 debug("session_by_tty: unknown tty %.100s", tty); 1976 session_dump(); 1977 return NULL; 1978 } 1979 1980 static Session * 1981 session_by_channel(int id) 1982 { 1983 int i; 1984 for (i = 0; i < sessions_nalloc; i++) { 1985 Session *s = &sessions[i]; 1986 if (s->used && s->chanid == id) { 1987 debug("session_by_channel: session %d channel %d", 1988 i, id); 1989 return s; 1990 } 1991 } 1992 debug("session_by_channel: unknown channel %d", id); 1993 session_dump(); 1994 return NULL; 1995 } 1996 1997 static Session * 1998 session_by_x11_channel(int id) 1999 { 2000 int i, j; 2001 2002 for (i = 0; i < sessions_nalloc; i++) { 2003 Session *s = &sessions[i]; 2004 2005 if (s->x11_chanids == NULL || !s->used) 2006 continue; 2007 for (j = 0; s->x11_chanids[j] != -1; j++) { 2008 if (s->x11_chanids[j] == id) { 2009 debug("session_by_x11_channel: session %d " 2010 "channel %d", s->self, id); 2011 return s; 2012 } 2013 } 2014 } 2015 debug("session_by_x11_channel: unknown channel %d", id); 2016 session_dump(); 2017 return NULL; 2018 } 2019 2020 static Session * 2021 session_by_pid(pid_t pid) 2022 { 2023 int i; 2024 debug("session_by_pid: pid %ld", (long)pid); 2025 for (i = 0; i < sessions_nalloc; i++) { 2026 Session *s = &sessions[i]; 2027 if (s->used && s->pid == pid) 2028 return s; 2029 } 2030 error("session_by_pid: unknown pid %ld", (long)pid); 2031 session_dump(); 2032 return NULL; 2033 } 2034 2035 static int 2036 session_window_change_req(Session *s) 2037 { 2038 s->col = packet_get_int(); 2039 s->row = packet_get_int(); 2040 s->xpixel = packet_get_int(); 2041 s->ypixel = packet_get_int(); 2042 packet_check_eom(); 2043 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 2044 return 1; 2045 } 2046 2047 static int 2048 session_pty_req(Session *s) 2049 { 2050 u_int len; 2051 int n_bytes; 2052 2053 if (no_pty_flag) { 2054 debug("Allocating a pty not permitted for this authentication."); 2055 return 0; 2056 } 2057 if (s->ttyfd != -1) { 2058 packet_disconnect("Protocol error: you already have a pty."); 2059 return 0; 2060 } 2061 2062 s->term = packet_get_string(&len); 2063 2064 if (compat20) { 2065 s->col = packet_get_int(); 2066 s->row = packet_get_int(); 2067 } else { 2068 s->row = packet_get_int(); 2069 s->col = packet_get_int(); 2070 } 2071 s->xpixel = packet_get_int(); 2072 s->ypixel = packet_get_int(); 2073 2074 if (strcmp(s->term, "") == 0) { 2075 xfree(s->term); 2076 s->term = NULL; 2077 } 2078 2079 /* Allocate a pty and open it. */ 2080 debug("Allocating pty."); 2081 if (!PRIVSEP(pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, 2082 sizeof(s->tty)))) { 2083 if (s->term) 2084 xfree(s->term); 2085 s->term = NULL; 2086 s->ptyfd = -1; 2087 s->ttyfd = -1; 2088 error("session_pty_req: session %d alloc failed", s->self); 2089 return 0; 2090 } 2091 debug("session_pty_req: session %d alloc %s", s->self, s->tty); 2092 2093 /* for SSH1 the tty modes length is not given */ 2094 if (!compat20) 2095 n_bytes = packet_remaining(); 2096 tty_parse_modes(s->ttyfd, &n_bytes); 2097 2098 if (!use_privsep) 2099 pty_setowner(s->pw, s->tty); 2100 2101 /* Set window size from the packet. */ 2102 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 2103 2104 packet_check_eom(); 2105 session_proctitle(s); 2106 return 1; 2107 } 2108 2109 static int 2110 session_subsystem_req(Session *s) 2111 { 2112 struct stat st; 2113 u_int len; 2114 int success = 0; 2115 char *prog, *cmd, *subsys = packet_get_string(&len); 2116 u_int i; 2117 2118 packet_check_eom(); 2119 logit("subsystem request for %.100s by user %s", subsys, 2120 s->pw->pw_name); 2121 2122 for (i = 0; i < options.num_subsystems; i++) { 2123 if (strcmp(subsys, options.subsystem_name[i]) == 0) { 2124 prog = options.subsystem_command[i]; 2125 cmd = options.subsystem_args[i]; 2126 if (strcmp(INTERNAL_SFTP_NAME, prog) == 0) { 2127 s->is_subsystem = SUBSYSTEM_INT_SFTP; 2128 debug("subsystem: %s", prog); 2129 } else { 2130 if (stat(prog, &st) < 0) 2131 debug("subsystem: cannot stat %s: %s", 2132 prog, strerror(errno)); 2133 s->is_subsystem = SUBSYSTEM_EXT; 2134 debug("subsystem: exec() %s", cmd); 2135 } 2136 success = do_exec(s, cmd) == 0; 2137 break; 2138 } 2139 } 2140 2141 if (!success) 2142 logit("subsystem request for %.100s failed, subsystem not found", 2143 subsys); 2144 2145 xfree(subsys); 2146 return success; 2147 } 2148 2149 static int 2150 session_x11_req(Session *s) 2151 { 2152 int success; 2153 2154 if (s->auth_proto != NULL || s->auth_data != NULL) { 2155 error("session_x11_req: session %d: " 2156 "x11 forwarding already active", s->self); 2157 return 0; 2158 } 2159 s->single_connection = packet_get_char(); 2160 s->auth_proto = packet_get_string(NULL); 2161 s->auth_data = packet_get_string(NULL); 2162 s->screen = packet_get_int(); 2163 packet_check_eom(); 2164 2165 success = session_setup_x11fwd(s); 2166 if (!success) { 2167 xfree(s->auth_proto); 2168 xfree(s->auth_data); 2169 s->auth_proto = NULL; 2170 s->auth_data = NULL; 2171 } 2172 return success; 2173 } 2174 2175 static int 2176 session_shell_req(Session *s) 2177 { 2178 packet_check_eom(); 2179 return do_exec(s, NULL) == 0; 2180 } 2181 2182 static int 2183 session_exec_req(Session *s) 2184 { 2185 u_int len, success; 2186 2187 char *command = packet_get_string(&len); 2188 packet_check_eom(); 2189 success = do_exec(s, command) == 0; 2190 xfree(command); 2191 return success; 2192 } 2193 2194 static int 2195 session_break_req(Session *s) 2196 { 2197 2198 packet_get_int(); /* ignored */ 2199 packet_check_eom(); 2200 2201 if (s->ttyfd == -1 || tcsendbreak(s->ttyfd, 0) < 0) 2202 return 0; 2203 return 1; 2204 } 2205 2206 static int 2207 session_env_req(Session *s) 2208 { 2209 char *name, *val; 2210 u_int name_len, val_len, i; 2211 2212 name = packet_get_string(&name_len); 2213 val = packet_get_string(&val_len); 2214 packet_check_eom(); 2215 2216 /* Don't set too many environment variables */ 2217 if (s->num_env > 128) { 2218 debug2("Ignoring env request %s: too many env vars", name); 2219 goto fail; 2220 } 2221 2222 for (i = 0; i < options.num_accept_env; i++) { 2223 if (match_pattern(name, options.accept_env[i])) { 2224 debug2("Setting env %d: %s=%s", s->num_env, name, val); 2225 s->env = xrealloc(s->env, s->num_env + 1, 2226 sizeof(*s->env)); 2227 s->env[s->num_env].name = name; 2228 s->env[s->num_env].val = val; 2229 s->num_env++; 2230 return (1); 2231 } 2232 } 2233 debug2("Ignoring env request %s: disallowed name", name); 2234 2235 fail: 2236 xfree(name); 2237 xfree(val); 2238 return (0); 2239 } 2240 2241 static int 2242 session_auth_agent_req(Session *s) 2243 { 2244 static int called = 0; 2245 packet_check_eom(); 2246 if (no_agent_forwarding_flag || !options.allow_agent_forwarding) { 2247 debug("session_auth_agent_req: no_agent_forwarding_flag"); 2248 return 0; 2249 } 2250 if (called) { 2251 return 0; 2252 } else { 2253 called = 1; 2254 return auth_input_request_forwarding(s->pw); 2255 } 2256 } 2257 2258 int 2259 session_input_channel_req(Channel *c, const char *rtype) 2260 { 2261 int success = 0; 2262 Session *s; 2263 2264 if ((s = session_by_channel(c->self)) == NULL) { 2265 logit("session_input_channel_req: no session %d req %.100s", 2266 c->self, rtype); 2267 return 0; 2268 } 2269 debug("session_input_channel_req: session %d req %s", s->self, rtype); 2270 2271 /* 2272 * a session is in LARVAL state until a shell, a command 2273 * or a subsystem is executed 2274 */ 2275 if (c->type == SSH_CHANNEL_LARVAL) { 2276 if (strcmp(rtype, "shell") == 0) { 2277 success = session_shell_req(s); 2278 } else if (strcmp(rtype, "exec") == 0) { 2279 success = session_exec_req(s); 2280 } else if (strcmp(rtype, "pty-req") == 0) { 2281 success = session_pty_req(s); 2282 } else if (strcmp(rtype, "x11-req") == 0) { 2283 success = session_x11_req(s); 2284 } else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) { 2285 success = session_auth_agent_req(s); 2286 } else if (strcmp(rtype, "subsystem") == 0) { 2287 success = session_subsystem_req(s); 2288 } else if (strcmp(rtype, "env") == 0) { 2289 success = session_env_req(s); 2290 } 2291 } 2292 if (strcmp(rtype, "window-change") == 0) { 2293 success = session_window_change_req(s); 2294 } else if (strcmp(rtype, "break") == 0) { 2295 success = session_break_req(s); 2296 } 2297 2298 return success; 2299 } 2300 2301 void 2302 session_set_fds(Session *s, int fdin, int fdout, int fderr, int ignore_fderr, 2303 int is_tty) 2304 { 2305 if (!compat20) 2306 fatal("session_set_fds: called for proto != 2.0"); 2307 /* 2308 * now that have a child and a pipe to the child, 2309 * we can activate our channel and register the fd's 2310 */ 2311 if (s->chanid == -1) 2312 fatal("no channel for session %d", s->self); 2313 if (options.hpn_disabled) 2314 channel_set_fds(s->chanid, 2315 fdout, fdin, fderr, 2316 ignore_fderr ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ, 2317 1, is_tty, CHAN_SES_WINDOW_DEFAULT); 2318 else 2319 channel_set_fds(s->chanid, 2320 fdout, fdin, fderr, 2321 ignore_fderr ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ, 2322 1, is_tty, options.hpn_buffer_size); 2323 } 2324 2325 /* 2326 * Function to perform pty cleanup. Also called if we get aborted abnormally 2327 * (e.g., due to a dropped connection). 2328 */ 2329 void 2330 session_pty_cleanup2(Session *s) 2331 { 2332 if (s == NULL) { 2333 error("session_pty_cleanup: no session"); 2334 return; 2335 } 2336 if (s->ttyfd == -1) 2337 return; 2338 2339 debug("session_pty_cleanup: session %d release %s", s->self, s->tty); 2340 2341 /* Record that the user has logged out. */ 2342 if (s->pid != 0) 2343 record_logout(s->pid, s->tty, s->pw->pw_name); 2344 2345 /* Release the pseudo-tty. */ 2346 if (getuid() == 0) 2347 pty_release(s->tty); 2348 2349 /* 2350 * Close the server side of the socket pairs. We must do this after 2351 * the pty cleanup, so that another process doesn't get this pty 2352 * while we're still cleaning up. 2353 */ 2354 if (s->ptymaster != -1 && close(s->ptymaster) < 0) 2355 error("close(s->ptymaster/%d): %s", 2356 s->ptymaster, strerror(errno)); 2357 2358 /* unlink pty from session */ 2359 s->ttyfd = -1; 2360 } 2361 2362 void 2363 session_pty_cleanup(Session *s) 2364 { 2365 PRIVSEP(session_pty_cleanup2(s)); 2366 } 2367 2368 static char * 2369 sig2name(int sig) 2370 { 2371 #define SSH_SIG(x) if (sig == SIG ## x) return #x 2372 SSH_SIG(ABRT); 2373 SSH_SIG(ALRM); 2374 SSH_SIG(FPE); 2375 SSH_SIG(HUP); 2376 SSH_SIG(ILL); 2377 SSH_SIG(INT); 2378 SSH_SIG(KILL); 2379 SSH_SIG(PIPE); 2380 SSH_SIG(QUIT); 2381 SSH_SIG(SEGV); 2382 SSH_SIG(TERM); 2383 SSH_SIG(USR1); 2384 SSH_SIG(USR2); 2385 #undef SSH_SIG 2386 return "SIG@openssh.com"; 2387 } 2388 2389 static void 2390 session_close_x11(int id) 2391 { 2392 Channel *c; 2393 2394 if ((c = channel_by_id(id)) == NULL) { 2395 debug("session_close_x11: x11 channel %d missing", id); 2396 } else { 2397 /* Detach X11 listener */ 2398 debug("session_close_x11: detach x11 channel %d", id); 2399 channel_cancel_cleanup(id); 2400 if (c->ostate != CHAN_OUTPUT_CLOSED) 2401 chan_mark_dead(c); 2402 } 2403 } 2404 2405 static void 2406 session_close_single_x11(int id, void *arg) 2407 { 2408 Session *s; 2409 u_int i; 2410 2411 debug3("session_close_single_x11: channel %d", id); 2412 channel_cancel_cleanup(id); 2413 if ((s = session_by_x11_channel(id)) == NULL) 2414 fatal("session_close_single_x11: no x11 channel %d", id); 2415 for (i = 0; s->x11_chanids[i] != -1; i++) { 2416 debug("session_close_single_x11: session %d: " 2417 "closing channel %d", s->self, s->x11_chanids[i]); 2418 /* 2419 * The channel "id" is already closing, but make sure we 2420 * close all of its siblings. 2421 */ 2422 if (s->x11_chanids[i] != id) 2423 session_close_x11(s->x11_chanids[i]); 2424 } 2425 xfree(s->x11_chanids); 2426 s->x11_chanids = NULL; 2427 if (s->display) { 2428 xfree(s->display); 2429 s->display = NULL; 2430 } 2431 if (s->auth_proto) { 2432 xfree(s->auth_proto); 2433 s->auth_proto = NULL; 2434 } 2435 if (s->auth_data) { 2436 xfree(s->auth_data); 2437 s->auth_data = NULL; 2438 } 2439 if (s->auth_display) { 2440 xfree(s->auth_display); 2441 s->auth_display = NULL; 2442 } 2443 } 2444 2445 static void 2446 session_exit_message(Session *s, int status) 2447 { 2448 Channel *c; 2449 2450 if ((c = channel_lookup(s->chanid)) == NULL) 2451 fatal("session_exit_message: session %d: no channel %d", 2452 s->self, s->chanid); 2453 debug("session_exit_message: session %d channel %d pid %ld", 2454 s->self, s->chanid, (long)s->pid); 2455 2456 if (WIFEXITED(status)) { 2457 channel_request_start(s->chanid, "exit-status", 0); 2458 packet_put_int(WEXITSTATUS(status)); 2459 packet_send(); 2460 } else if (WIFSIGNALED(status)) { 2461 channel_request_start(s->chanid, "exit-signal", 0); 2462 packet_put_cstring(sig2name(WTERMSIG(status))); 2463 #ifdef WCOREDUMP 2464 packet_put_char(WCOREDUMP(status)? 1 : 0); 2465 #else /* WCOREDUMP */ 2466 packet_put_char(0); 2467 #endif /* WCOREDUMP */ 2468 packet_put_cstring(""); 2469 packet_put_cstring(""); 2470 packet_send(); 2471 } else { 2472 /* Some weird exit cause. Just exit. */ 2473 packet_disconnect("wait returned status %04x.", status); 2474 } 2475 2476 /* disconnect channel */ 2477 debug("session_exit_message: release channel %d", s->chanid); 2478 2479 /* 2480 * Adjust cleanup callback attachment to send close messages when 2481 * the channel gets EOF. The session will be then be closed 2482 * by session_close_by_channel when the childs close their fds. 2483 */ 2484 channel_register_cleanup(c->self, session_close_by_channel, 1); 2485 2486 /* 2487 * emulate a write failure with 'chan_write_failed', nobody will be 2488 * interested in data we write. 2489 * Note that we must not call 'chan_read_failed', since there could 2490 * be some more data waiting in the pipe. 2491 */ 2492 if (c->ostate != CHAN_OUTPUT_CLOSED) 2493 chan_write_failed(c); 2494 } 2495 2496 void 2497 session_close(Session *s) 2498 { 2499 u_int i; 2500 2501 debug("session_close: session %d pid %ld", s->self, (long)s->pid); 2502 if (s->ttyfd != -1) 2503 session_pty_cleanup(s); 2504 if (s->term) 2505 xfree(s->term); 2506 if (s->display) 2507 xfree(s->display); 2508 if (s->x11_chanids) 2509 xfree(s->x11_chanids); 2510 if (s->auth_display) 2511 xfree(s->auth_display); 2512 if (s->auth_data) 2513 xfree(s->auth_data); 2514 if (s->auth_proto) 2515 xfree(s->auth_proto); 2516 if (s->env != NULL) { 2517 for (i = 0; i < s->num_env; i++) { 2518 xfree(s->env[i].name); 2519 xfree(s->env[i].val); 2520 } 2521 xfree(s->env); 2522 } 2523 session_proctitle(s); 2524 session_unused(s->self); 2525 } 2526 2527 void 2528 session_close_by_pid(pid_t pid, int status) 2529 { 2530 Session *s = session_by_pid(pid); 2531 if (s == NULL) { 2532 debug("session_close_by_pid: no session for pid %ld", 2533 (long)pid); 2534 return; 2535 } 2536 if (s->chanid != -1) 2537 session_exit_message(s, status); 2538 if (s->ttyfd != -1) 2539 session_pty_cleanup(s); 2540 s->pid = 0; 2541 } 2542 2543 /* 2544 * this is called when a channel dies before 2545 * the session 'child' itself dies 2546 */ 2547 void 2548 session_close_by_channel(int id, void *arg) 2549 { 2550 Session *s = session_by_channel(id); 2551 u_int i; 2552 2553 if (s == NULL) { 2554 debug("session_close_by_channel: no session for id %d", id); 2555 return; 2556 } 2557 debug("session_close_by_channel: channel %d child %ld", 2558 id, (long)s->pid); 2559 if (s->pid != 0) { 2560 debug("session_close_by_channel: channel %d: has child", id); 2561 /* 2562 * delay detach of session, but release pty, since 2563 * the fd's to the child are already closed 2564 */ 2565 if (s->ttyfd != -1) 2566 session_pty_cleanup(s); 2567 return; 2568 } 2569 /* detach by removing callback */ 2570 channel_cancel_cleanup(s->chanid); 2571 2572 /* Close any X11 listeners associated with this session */ 2573 if (s->x11_chanids != NULL) { 2574 for (i = 0; s->x11_chanids[i] != -1; i++) { 2575 session_close_x11(s->x11_chanids[i]); 2576 s->x11_chanids[i] = -1; 2577 } 2578 } 2579 2580 s->chanid = -1; 2581 session_close(s); 2582 } 2583 2584 void 2585 session_destroy_all(void (*closefunc)(Session *)) 2586 { 2587 int i; 2588 for (i = 0; i < sessions_nalloc; i++) { 2589 Session *s = &sessions[i]; 2590 if (s->used) { 2591 if (closefunc != NULL) 2592 closefunc(s); 2593 else 2594 session_close(s); 2595 } 2596 } 2597 } 2598 2599 static char * 2600 session_tty_list(void) 2601 { 2602 static char buf[1024]; 2603 int i; 2604 char *cp; 2605 2606 buf[0] = '\0'; 2607 for (i = 0; i < sessions_nalloc; i++) { 2608 Session *s = &sessions[i]; 2609 if (s->used && s->ttyfd != -1) { 2610 2611 if (strncmp(s->tty, "/dev/", 5) != 0) { 2612 cp = strrchr(s->tty, '/'); 2613 cp = (cp == NULL) ? s->tty : cp + 1; 2614 } else 2615 cp = s->tty + 5; 2616 2617 if (buf[0] != '\0') 2618 strlcat(buf, ",", sizeof buf); 2619 strlcat(buf, cp, sizeof buf); 2620 } 2621 } 2622 if (buf[0] == '\0') 2623 strlcpy(buf, "notty", sizeof buf); 2624 return buf; 2625 } 2626 2627 void 2628 session_proctitle(Session *s) 2629 { 2630 if (s->pw == NULL) 2631 error("no user for session %d", s->self); 2632 else 2633 setproctitle("%s@%s", s->pw->pw_name, session_tty_list()); 2634 } 2635 2636 int 2637 session_setup_x11fwd(Session *s) 2638 { 2639 struct stat st; 2640 char display[512], auth_display[512]; 2641 char hostname[MAXHOSTNAMELEN]; 2642 u_int i; 2643 2644 if (no_x11_forwarding_flag) { 2645 packet_send_debug("X11 forwarding disabled in user configuration file."); 2646 return 0; 2647 } 2648 if (!options.x11_forwarding) { 2649 debug("X11 forwarding disabled in server configuration file."); 2650 return 0; 2651 } 2652 if (!options.xauth_location || 2653 (stat(options.xauth_location, &st) == -1)) { 2654 packet_send_debug("No xauth program; cannot forward with spoofing."); 2655 return 0; 2656 } 2657 if (options.use_login) { 2658 packet_send_debug("X11 forwarding disabled; " 2659 "not compatible with UseLogin=yes."); 2660 return 0; 2661 } 2662 if (s->display != NULL) { 2663 debug("X11 display already set."); 2664 return 0; 2665 } 2666 if (x11_create_display_inet(options.x11_display_offset, 2667 options.x11_use_localhost, s->single_connection, 2668 &s->display_number, &s->x11_chanids) == -1) { 2669 debug("x11_create_display_inet failed."); 2670 return 0; 2671 } 2672 for (i = 0; s->x11_chanids[i] != -1; i++) { 2673 channel_register_cleanup(s->x11_chanids[i], 2674 session_close_single_x11, 0); 2675 } 2676 2677 /* Set up a suitable value for the DISPLAY variable. */ 2678 if (gethostname(hostname, sizeof(hostname)) < 0) 2679 fatal("gethostname: %.100s", strerror(errno)); 2680 /* 2681 * auth_display must be used as the displayname when the 2682 * authorization entry is added with xauth(1). This will be 2683 * different than the DISPLAY string for localhost displays. 2684 */ 2685 if (options.x11_use_localhost) { 2686 snprintf(display, sizeof display, "localhost:%u.%u", 2687 s->display_number, s->screen); 2688 snprintf(auth_display, sizeof auth_display, "unix:%u.%u", 2689 s->display_number, s->screen); 2690 s->display = xstrdup(display); 2691 s->auth_display = xstrdup(auth_display); 2692 } else { 2693 #ifdef IPADDR_IN_DISPLAY 2694 struct hostent *he; 2695 struct in_addr my_addr; 2696 2697 he = gethostbyname(hostname); 2698 if (he == NULL) { 2699 error("Can't get IP address for X11 DISPLAY."); 2700 packet_send_debug("Can't get IP address for X11 DISPLAY."); 2701 return 0; 2702 } 2703 memcpy(&my_addr, he->h_addr_list[0], sizeof(struct in_addr)); 2704 snprintf(display, sizeof display, "%.50s:%u.%u", inet_ntoa(my_addr), 2705 s->display_number, s->screen); 2706 #else 2707 snprintf(display, sizeof display, "%.400s:%u.%u", hostname, 2708 s->display_number, s->screen); 2709 #endif 2710 s->display = xstrdup(display); 2711 s->auth_display = xstrdup(display); 2712 } 2713 2714 return 1; 2715 } 2716 2717 static void 2718 do_authenticated2(Authctxt *authctxt) 2719 { 2720 server_loop2(authctxt); 2721 } 2722 2723 void 2724 do_cleanup(Authctxt *authctxt) 2725 { 2726 static int called = 0; 2727 2728 debug("do_cleanup"); 2729 2730 /* no cleanup if we're in the child for login shell */ 2731 if (is_child) 2732 return; 2733 2734 /* avoid double cleanup */ 2735 if (called) 2736 return; 2737 called = 1; 2738 2739 if (authctxt == NULL) 2740 return; 2741 2742 #ifdef USE_PAM 2743 if (options.use_pam) { 2744 sshpam_cleanup(); 2745 sshpam_thread_cleanup(); 2746 } 2747 #endif 2748 2749 if (!authctxt->authenticated) 2750 return; 2751 2752 #ifdef KRB5 2753 if (options.kerberos_ticket_cleanup && 2754 authctxt->krb5_ctx) 2755 krb5_cleanup_proc(authctxt); 2756 #endif 2757 2758 #ifdef GSSAPI 2759 if (compat20 && options.gss_cleanup_creds) 2760 ssh_gssapi_cleanup_creds(); 2761 #endif 2762 2763 /* remove agent socket */ 2764 auth_sock_cleanup_proc(authctxt->pw); 2765 2766 /* 2767 * Cleanup ptys/utmp only if privsep is disabled, 2768 * or if running in monitor. 2769 */ 2770 if (!use_privsep || mm_is_monitor()) 2771 session_destroy_all(session_pty_cleanup2); 2772 } 2773