session.c revision 192595
1/* $OpenBSD: session.c,v 1.245 2009/01/22 09:46:01 djm Exp $ */ 2/* 3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 4 * All rights reserved 5 * 6 * As far as I am concerned, the code I have written for this software 7 * can be used freely for any purpose. Any derived versions of this 8 * software must be clearly marked as such, and if the derived work is 9 * incompatible with the protocol description in the RFC file, it must be 10 * called by a name other than "ssh" or "Secure Shell". 11 * 12 * SSH2 support by Markus Friedl. 13 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 14 * 15 * Redistribution and use in source and binary forms, with or without 16 * modification, are permitted provided that the following conditions 17 * are met: 18 * 1. Redistributions of source code must retain the above copyright 19 * notice, this list of conditions and the following disclaimer. 20 * 2. Redistributions in binary form must reproduce the above copyright 21 * notice, this list of conditions and the following disclaimer in the 22 * documentation and/or other materials provided with the distribution. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 25 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 26 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 27 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 28 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 29 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 30 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 31 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 32 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 33 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 34 */ 35 36#include "includes.h" 37__RCSID("$FreeBSD: head/crypto/openssh/session.c 192595 2009-05-22 18:46:28Z des $"); 38 39#include <sys/types.h> 40#include <sys/param.h> 41#ifdef HAVE_SYS_STAT_H 42# include <sys/stat.h> 43#endif 44#include <sys/socket.h> 45#include <sys/un.h> 46#include <sys/wait.h> 47 48#include <arpa/inet.h> 49 50#include <errno.h> 51#include <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 107Session *session_new(void); 108void session_set_fds(Session *, int, int, int, int); 109void session_pty_cleanup(Session *); 110void session_proctitle(Session *); 111int session_setup_x11fwd(Session *); 112int do_exec_pty(Session *, const char *); 113int do_exec_no_pty(Session *, const char *); 114int do_exec(Session *, const char *); 115void do_login(Session *, const char *); 116#ifdef LOGIN_NEEDS_UTMPX 117static void do_pre_login(Session *s); 118#endif 119void do_child(Session *, const char *); 120void do_motd(void); 121int check_quietlogin(Session *, const char *); 122 123static void do_authenticated1(Authctxt *); 124static void do_authenticated2(Authctxt *); 125 126static int session_pty_req(Session *); 127 128/* import */ 129extern ServerOptions options; 130extern char *__progname; 131extern int log_stderr; 132extern int debug_flag; 133extern u_int utmp_len; 134extern int startup_pipe; 135extern void destroy_sensitive_data(void); 136extern Buffer loginmsg; 137 138/* original command from peer. */ 139const char *original_command = NULL; 140 141/* data */ 142static int sessions_first_unused = -1; 143static int sessions_nalloc = 0; 144static Session *sessions = NULL; 145 146#define SUBSYSTEM_NONE 0 147#define SUBSYSTEM_EXT 1 148#define SUBSYSTEM_INT_SFTP 2 149 150#ifdef HAVE_LOGIN_CAP 151login_cap_t *lc; 152#endif 153 154static int is_child = 0; 155 156/* Name and directory of socket for authentication agent forwarding. */ 157static char *auth_sock_name = NULL; 158static char *auth_sock_dir = NULL; 159 160/* removes the agent forwarding socket */ 161 162static void 163auth_sock_cleanup_proc(struct passwd *pw) 164{ 165 if (auth_sock_name != NULL) { 166 temporarily_use_uid(pw); 167 unlink(auth_sock_name); 168 rmdir(auth_sock_dir); 169 auth_sock_name = NULL; 170 restore_uid(); 171 } 172} 173 174static int 175auth_input_request_forwarding(struct passwd * pw) 176{ 177 Channel *nc; 178 int sock = -1; 179 struct sockaddr_un sunaddr; 180 181 if (auth_sock_name != NULL) { 182 error("authentication forwarding requested twice."); 183 return 0; 184 } 185 186 /* Temporarily drop privileged uid for mkdir/bind. */ 187 temporarily_use_uid(pw); 188 189 /* Allocate a buffer for the socket name, and format the name. */ 190 auth_sock_dir = xstrdup("/tmp/ssh-XXXXXXXXXX"); 191 192 /* Create private directory for socket */ 193 if (mkdtemp(auth_sock_dir) == NULL) { 194 packet_send_debug("Agent forwarding disabled: " 195 "mkdtemp() failed: %.100s", strerror(errno)); 196 restore_uid(); 197 xfree(auth_sock_dir); 198 auth_sock_dir = NULL; 199 goto authsock_err; 200 } 201 202 xasprintf(&auth_sock_name, "%s/agent.%ld", 203 auth_sock_dir, (long) getpid()); 204 205 /* Create the socket. */ 206 sock = socket(AF_UNIX, SOCK_STREAM, 0); 207 if (sock < 0) { 208 error("socket: %.100s", strerror(errno)); 209 restore_uid(); 210 goto authsock_err; 211 } 212 213 /* Bind it to the name. */ 214 memset(&sunaddr, 0, sizeof(sunaddr)); 215 sunaddr.sun_family = AF_UNIX; 216 strlcpy(sunaddr.sun_path, auth_sock_name, sizeof(sunaddr.sun_path)); 217 218 if (bind(sock, (struct sockaddr *)&sunaddr, sizeof(sunaddr)) < 0) { 219 error("bind: %.100s", strerror(errno)); 220 restore_uid(); 221 goto authsock_err; 222 } 223 224 /* Restore the privileged uid. */ 225 restore_uid(); 226 227 /* Start listening on the socket. */ 228 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) { 229 error("listen: %.100s", strerror(errno)); 230 goto authsock_err; 231 } 232 233 /* Allocate a channel for the authentication agent socket. */ 234 nc = channel_new("auth socket", 235 SSH_CHANNEL_AUTH_SOCKET, sock, sock, -1, 236 CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 237 0, "auth socket", 1); 238 nc->path = xstrdup(auth_sock_name); 239 return 1; 240 241 authsock_err: 242 if (auth_sock_name != NULL) 243 xfree(auth_sock_name); 244 if (auth_sock_dir != NULL) { 245 rmdir(auth_sock_dir); 246 xfree(auth_sock_dir); 247 } 248 if (sock != -1) 249 close(sock); 250 auth_sock_name = NULL; 251 auth_sock_dir = NULL; 252 return 0; 253} 254 255static void 256display_loginmsg(void) 257{ 258 if (buffer_len(&loginmsg) > 0) { 259 buffer_append(&loginmsg, "\0", 1); 260 printf("%s", (char *)buffer_ptr(&loginmsg)); 261 buffer_clear(&loginmsg); 262 } 263} 264 265void 266do_authenticated(Authctxt *authctxt) 267{ 268 setproctitle("%s", authctxt->pw->pw_name); 269 270 /* setup the channel layer */ 271 if (!no_port_forwarding_flag && options.allow_tcp_forwarding) 272 channel_permit_all_opens(); 273 274 if (compat20) 275 do_authenticated2(authctxt); 276 else 277 do_authenticated1(authctxt); 278 279 do_cleanup(authctxt); 280} 281 282/* 283 * Prepares for an interactive session. This is called after the user has 284 * been successfully authenticated. During this message exchange, pseudo 285 * terminals are allocated, X11, TCP/IP, and authentication agent forwardings 286 * are requested, etc. 287 */ 288static void 289do_authenticated1(Authctxt *authctxt) 290{ 291 Session *s; 292 char *command; 293 int success, type, screen_flag; 294 int enable_compression_after_reply = 0; 295 u_int proto_len, data_len, dlen, compression_level = 0; 296 297 s = session_new(); 298 if (s == NULL) { 299 error("no more sessions"); 300 return; 301 } 302 s->authctxt = authctxt; 303 s->pw = authctxt->pw; 304 305 /* 306 * We stay in this loop until the client requests to execute a shell 307 * or a command. 308 */ 309 for (;;) { 310 success = 0; 311 312 /* Get a packet from the client. */ 313 type = packet_read(); 314 315 /* Process the packet. */ 316 switch (type) { 317 case SSH_CMSG_REQUEST_COMPRESSION: 318 compression_level = packet_get_int(); 319 packet_check_eom(); 320 if (compression_level < 1 || compression_level > 9) { 321 packet_send_debug("Received invalid compression level %d.", 322 compression_level); 323 break; 324 } 325 if (options.compression == COMP_NONE) { 326 debug2("compression disabled"); 327 break; 328 } 329 /* Enable compression after we have responded with SUCCESS. */ 330 enable_compression_after_reply = 1; 331 success = 1; 332 break; 333 334 case SSH_CMSG_REQUEST_PTY: 335 success = session_pty_req(s); 336 break; 337 338 case SSH_CMSG_X11_REQUEST_FORWARDING: 339 s->auth_proto = packet_get_string(&proto_len); 340 s->auth_data = packet_get_string(&data_len); 341 342 screen_flag = packet_get_protocol_flags() & 343 SSH_PROTOFLAG_SCREEN_NUMBER; 344 debug2("SSH_PROTOFLAG_SCREEN_NUMBER: %d", screen_flag); 345 346 if (packet_remaining() == 4) { 347 if (!screen_flag) 348 debug2("Buggy client: " 349 "X11 screen flag missing"); 350 s->screen = packet_get_int(); 351 } else { 352 s->screen = 0; 353 } 354 packet_check_eom(); 355 success = session_setup_x11fwd(s); 356 if (!success) { 357 xfree(s->auth_proto); 358 xfree(s->auth_data); 359 s->auth_proto = NULL; 360 s->auth_data = NULL; 361 } 362 break; 363 364 case SSH_CMSG_AGENT_REQUEST_FORWARDING: 365 if (!options.allow_agent_forwarding || 366 no_agent_forwarding_flag || compat13) { 367 debug("Authentication agent forwarding not permitted for this authentication."); 368 break; 369 } 370 debug("Received authentication agent forwarding request."); 371 success = auth_input_request_forwarding(s->pw); 372 break; 373 374 case SSH_CMSG_PORT_FORWARD_REQUEST: 375 if (no_port_forwarding_flag) { 376 debug("Port forwarding not permitted for this authentication."); 377 break; 378 } 379 if (!options.allow_tcp_forwarding) { 380 debug("Port forwarding not permitted."); 381 break; 382 } 383 debug("Received TCP/IP port forwarding request."); 384 if (channel_input_port_forward_request(s->pw->pw_uid == 0, 385 options.gateway_ports) < 0) { 386 debug("Port forwarding failed."); 387 break; 388 } 389 success = 1; 390 break; 391 392 case SSH_CMSG_MAX_PACKET_SIZE: 393 if (packet_set_maxsize(packet_get_int()) > 0) 394 success = 1; 395 break; 396 397 case SSH_CMSG_EXEC_SHELL: 398 case SSH_CMSG_EXEC_CMD: 399 if (type == SSH_CMSG_EXEC_CMD) { 400 command = packet_get_string(&dlen); 401 debug("Exec command '%.500s'", command); 402 if (do_exec(s, command) != 0) 403 packet_disconnect( 404 "command execution failed"); 405 xfree(command); 406 } else { 407 if (do_exec(s, NULL) != 0) 408 packet_disconnect( 409 "shell execution failed"); 410 } 411 packet_check_eom(); 412 session_close(s); 413 return; 414 415 default: 416 /* 417 * Any unknown messages in this phase are ignored, 418 * and a failure message is returned. 419 */ 420 logit("Unknown packet type received after authentication: %d", type); 421 } 422 packet_start(success ? SSH_SMSG_SUCCESS : SSH_SMSG_FAILURE); 423 packet_send(); 424 packet_write_wait(); 425 426 /* Enable compression now that we have replied if appropriate. */ 427 if (enable_compression_after_reply) { 428 enable_compression_after_reply = 0; 429 packet_start_compression(compression_level); 430 } 431 } 432} 433 434#define USE_PIPES 435/* 436 * This is called to fork and execute a command when we have no tty. This 437 * will call do_child from the child, and server_loop from the parent after 438 * setting up file descriptors and such. 439 */ 440int 441do_exec_no_pty(Session *s, const char *command) 442{ 443 pid_t pid; 444 445#ifdef USE_PIPES 446 int pin[2], pout[2], perr[2]; 447 448 /* Allocate pipes for communicating with the program. */ 449 if (pipe(pin) < 0) { 450 error("%s: pipe in: %.100s", __func__, strerror(errno)); 451 return -1; 452 } 453 if (pipe(pout) < 0) { 454 error("%s: pipe out: %.100s", __func__, strerror(errno)); 455 close(pin[0]); 456 close(pin[1]); 457 return -1; 458 } 459 if (pipe(perr) < 0) { 460 error("%s: pipe err: %.100s", __func__, strerror(errno)); 461 close(pin[0]); 462 close(pin[1]); 463 close(pout[0]); 464 close(pout[1]); 465 return -1; 466 } 467#else 468 int inout[2], err[2]; 469 470 /* Uses socket pairs to communicate with the program. */ 471 if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) < 0) { 472 error("%s: socketpair #1: %.100s", __func__, strerror(errno)); 473 return -1; 474 } 475 if (socketpair(AF_UNIX, SOCK_STREAM, 0, err) < 0) { 476 error("%s: socketpair #2: %.100s", __func__, strerror(errno)); 477 close(inout[0]); 478 close(inout[1]); 479 return -1; 480 } 481#endif 482 483 if (s == NULL) 484 fatal("do_exec_no_pty: no session"); 485 486 session_proctitle(s); 487 488 /* Fork the child. */ 489 switch ((pid = fork())) { 490 case -1: 491 error("%s: fork: %.100s", __func__, strerror(errno)); 492#ifdef USE_PIPES 493 close(pin[0]); 494 close(pin[1]); 495 close(pout[0]); 496 close(pout[1]); 497 close(perr[0]); 498 close(perr[1]); 499#else 500 close(inout[0]); 501 close(inout[1]); 502 close(err[0]); 503 close(err[1]); 504#endif 505 return -1; 506 case 0: 507 is_child = 1; 508 509 /* Child. Reinitialize the log since the pid has changed. */ 510 log_init(__progname, options.log_level, 511 options.log_facility, log_stderr); 512 513 /* 514 * Create a new session and process group since the 4.4BSD 515 * setlogin() affects the entire process group. 516 */ 517 if (setsid() < 0) 518 error("setsid failed: %.100s", strerror(errno)); 519 520#ifdef USE_PIPES 521 /* 522 * Redirect stdin. We close the parent side of the socket 523 * pair, and make the child side the standard input. 524 */ 525 close(pin[1]); 526 if (dup2(pin[0], 0) < 0) 527 perror("dup2 stdin"); 528 close(pin[0]); 529 530 /* Redirect stdout. */ 531 close(pout[0]); 532 if (dup2(pout[1], 1) < 0) 533 perror("dup2 stdout"); 534 close(pout[1]); 535 536 /* Redirect stderr. */ 537 close(perr[0]); 538 if (dup2(perr[1], 2) < 0) 539 perror("dup2 stderr"); 540 close(perr[1]); 541#else 542 /* 543 * Redirect stdin, stdout, and stderr. Stdin and stdout will 544 * use the same socket, as some programs (particularly rdist) 545 * seem to depend on it. 546 */ 547 close(inout[1]); 548 close(err[1]); 549 if (dup2(inout[0], 0) < 0) /* stdin */ 550 perror("dup2 stdin"); 551 if (dup2(inout[0], 1) < 0) /* stdout (same as stdin) */ 552 perror("dup2 stdout"); 553 close(inout[0]); 554 if (dup2(err[0], 2) < 0) /* stderr */ 555 perror("dup2 stderr"); 556 close(err[0]); 557#endif 558 559 560#ifdef _UNICOS 561 cray_init_job(s->pw); /* set up cray jid and tmpdir */ 562#endif 563 564 /* Do processing for the child (exec command etc). */ 565 do_child(s, command); 566 /* NOTREACHED */ 567 default: 568 break; 569 } 570 571#ifdef _UNICOS 572 signal(WJSIGNAL, cray_job_termination_handler); 573#endif /* _UNICOS */ 574#ifdef HAVE_CYGWIN 575 if (is_winnt) 576 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); 577#endif 578 579 s->pid = pid; 580 /* Set interactive/non-interactive mode. */ 581 packet_set_interactive(s->display != NULL); 582 583 /* 584 * Clear loginmsg, since it's the child's responsibility to display 585 * it to the user, otherwise multiple sessions may accumulate 586 * multiple copies of the login messages. 587 */ 588 buffer_clear(&loginmsg); 589 590#ifdef USE_PIPES 591 /* We are the parent. Close the child sides of the pipes. */ 592 close(pin[0]); 593 close(pout[1]); 594 close(perr[1]); 595 596 if (compat20) { 597 if (s->is_subsystem) { 598 close(perr[0]); 599 perr[0] = -1; 600 } 601 session_set_fds(s, pin[1], pout[0], perr[0], 0); 602 } else { 603 /* Enter the interactive session. */ 604 server_loop(pid, pin[1], pout[0], perr[0]); 605 /* server_loop has closed pin[1], pout[0], and perr[0]. */ 606 } 607#else 608 /* We are the parent. Close the child sides of the socket pairs. */ 609 close(inout[0]); 610 close(err[0]); 611 612 /* 613 * Enter the interactive session. Note: server_loop must be able to 614 * handle the case that fdin and fdout are the same. 615 */ 616 if (compat20) { 617 session_set_fds(s, inout[1], inout[1], 618 s->is_subsystem ? -1 : err[1], 0); 619 if (s->is_subsystem) 620 close(err[1]); 621 } else { 622 server_loop(pid, inout[1], inout[1], err[1]); 623 /* server_loop has closed inout[1] and err[1]. */ 624 } 625#endif 626 return 0; 627} 628 629/* 630 * This is called to fork and execute a command when we have a tty. This 631 * will call do_child from the child, and server_loop from the parent after 632 * setting up file descriptors, controlling tty, updating wtmp, utmp, 633 * lastlog, and other such operations. 634 */ 635int 636do_exec_pty(Session *s, const char *command) 637{ 638 int fdout, ptyfd, ttyfd, ptymaster; 639 pid_t pid; 640 641 if (s == NULL) 642 fatal("do_exec_pty: no session"); 643 ptyfd = s->ptyfd; 644 ttyfd = s->ttyfd; 645 646 /* 647 * Create another descriptor of the pty master side for use as the 648 * standard input. We could use the original descriptor, but this 649 * simplifies code in server_loop. The descriptor is bidirectional. 650 * Do this before forking (and cleanup in the child) so as to 651 * detect and gracefully fail out-of-fd conditions. 652 */ 653 if ((fdout = dup(ptyfd)) < 0) { 654 error("%s: dup #1: %s", __func__, strerror(errno)); 655 close(ttyfd); 656 close(ptyfd); 657 return -1; 658 } 659 /* we keep a reference to the pty master */ 660 if ((ptymaster = dup(ptyfd)) < 0) { 661 error("%s: dup #2: %s", __func__, strerror(errno)); 662 close(ttyfd); 663 close(ptyfd); 664 close(fdout); 665 return -1; 666 } 667 668 /* Fork the child. */ 669 switch ((pid = fork())) { 670 case -1: 671 error("%s: fork: %.100s", __func__, strerror(errno)); 672 close(fdout); 673 close(ptymaster); 674 close(ttyfd); 675 close(ptyfd); 676 return -1; 677 case 0: 678 is_child = 1; 679 680 close(fdout); 681 close(ptymaster); 682 683 /* Child. Reinitialize the log because the pid has changed. */ 684 log_init(__progname, options.log_level, 685 options.log_facility, log_stderr); 686 /* Close the master side of the pseudo tty. */ 687 close(ptyfd); 688 689 /* Make the pseudo tty our controlling tty. */ 690 pty_make_controlling_tty(&ttyfd, s->tty); 691 692 /* Redirect stdin/stdout/stderr from the pseudo tty. */ 693 if (dup2(ttyfd, 0) < 0) 694 error("dup2 stdin: %s", strerror(errno)); 695 if (dup2(ttyfd, 1) < 0) 696 error("dup2 stdout: %s", strerror(errno)); 697 if (dup2(ttyfd, 2) < 0) 698 error("dup2 stderr: %s", strerror(errno)); 699 700 /* Close the extra descriptor for the pseudo tty. */ 701 close(ttyfd); 702 703 /* record login, etc. similar to login(1) */ 704#ifndef HAVE_OSF_SIA 705 if (!(options.use_login && command == NULL)) { 706#ifdef _UNICOS 707 cray_init_job(s->pw); /* set up cray jid and tmpdir */ 708#endif /* _UNICOS */ 709 do_login(s, command); 710 } 711# ifdef LOGIN_NEEDS_UTMPX 712 else 713 do_pre_login(s); 714# endif 715#endif 716 /* 717 * Do common processing for the child, such as execing 718 * the command. 719 */ 720 do_child(s, command); 721 /* NOTREACHED */ 722 default: 723 break; 724 } 725 726#ifdef _UNICOS 727 signal(WJSIGNAL, cray_job_termination_handler); 728#endif /* _UNICOS */ 729#ifdef HAVE_CYGWIN 730 if (is_winnt) 731 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); 732#endif 733 734 s->pid = pid; 735 736 /* Parent. Close the slave side of the pseudo tty. */ 737 close(ttyfd); 738 739 /* Enter interactive session. */ 740 s->ptymaster = ptymaster; 741 packet_set_interactive(1); 742 if (compat20) { 743 session_set_fds(s, ptyfd, fdout, -1, 1); 744 } else { 745 server_loop(pid, ptyfd, fdout, -1); 746 /* server_loop _has_ closed ptyfd and fdout. */ 747 } 748 return 0; 749} 750 751#ifdef LOGIN_NEEDS_UTMPX 752static void 753do_pre_login(Session *s) 754{ 755 socklen_t fromlen; 756 struct sockaddr_storage from; 757 pid_t pid = getpid(); 758 759 /* 760 * Get IP address of client. If the connection is not a socket, let 761 * the address be 0.0.0.0. 762 */ 763 memset(&from, 0, sizeof(from)); 764 fromlen = sizeof(from); 765 if (packet_connection_is_on_socket()) { 766 if (getpeername(packet_get_connection_in(), 767 (struct sockaddr *)&from, &fromlen) < 0) { 768 debug("getpeername: %.100s", strerror(errno)); 769 cleanup_exit(255); 770 } 771 } 772 773 record_utmp_only(pid, s->tty, s->pw->pw_name, 774 get_remote_name_or_ip(utmp_len, options.use_dns), 775 (struct sockaddr *)&from, fromlen); 776} 777#endif 778 779/* 780 * This is called to fork and execute a command. If another command is 781 * to be forced, execute that instead. 782 */ 783int 784do_exec(Session *s, const char *command) 785{ 786 int ret; 787 788 if (options.adm_forced_command) { 789 original_command = command; 790 command = options.adm_forced_command; 791 if (IS_INTERNAL_SFTP(command)) 792 s->is_subsystem = SUBSYSTEM_INT_SFTP; 793 else if (s->is_subsystem) 794 s->is_subsystem = SUBSYSTEM_EXT; 795 debug("Forced command (config) '%.900s'", command); 796 } else if (forced_command) { 797 original_command = command; 798 command = forced_command; 799 if (IS_INTERNAL_SFTP(command)) 800 s->is_subsystem = SUBSYSTEM_INT_SFTP; 801 else if (s->is_subsystem) 802 s->is_subsystem = SUBSYSTEM_EXT; 803 debug("Forced command (key option) '%.900s'", command); 804 } 805 806#ifdef SSH_AUDIT_EVENTS 807 if (command != NULL) 808 PRIVSEP(audit_run_command(command)); 809 else if (s->ttyfd == -1) { 810 char *shell = s->pw->pw_shell; 811 812 if (shell[0] == '\0') /* empty shell means /bin/sh */ 813 shell =_PATH_BSHELL; 814 PRIVSEP(audit_run_command(shell)); 815 } 816#endif 817 if (s->ttyfd != -1) 818 ret = do_exec_pty(s, command); 819 else 820 ret = do_exec_no_pty(s, command); 821 822 original_command = NULL; 823 824 /* 825 * Clear loginmsg: it's the child's responsibility to display 826 * it to the user, otherwise multiple sessions may accumulate 827 * multiple copies of the login messages. 828 */ 829 buffer_clear(&loginmsg); 830 831 return ret; 832} 833 834/* administrative, login(1)-like work */ 835void 836do_login(Session *s, const char *command) 837{ 838 socklen_t fromlen; 839 struct sockaddr_storage from; 840 struct passwd * pw = s->pw; 841 pid_t pid = getpid(); 842 843 /* 844 * Get IP address of client. If the connection is not a socket, let 845 * the address be 0.0.0.0. 846 */ 847 memset(&from, 0, sizeof(from)); 848 fromlen = sizeof(from); 849 if (packet_connection_is_on_socket()) { 850 if (getpeername(packet_get_connection_in(), 851 (struct sockaddr *) & from, &fromlen) < 0) { 852 debug("getpeername: %.100s", strerror(errno)); 853 cleanup_exit(255); 854 } 855 } 856 857 /* Record that there was a login on that tty from the remote host. */ 858 if (!use_privsep) 859 record_login(pid, s->tty, pw->pw_name, pw->pw_uid, 860 get_remote_name_or_ip(utmp_len, 861 options.use_dns), 862 (struct sockaddr *)&from, fromlen); 863 864#ifdef USE_PAM 865 /* 866 * If password change is needed, do it now. 867 * This needs to occur before the ~/.hushlogin check. 868 */ 869 if (options.use_pam && !use_privsep && s->authctxt->force_pwchange) { 870 display_loginmsg(); 871 do_pam_chauthtok(); 872 s->authctxt->force_pwchange = 0; 873 /* XXX - signal [net] parent to enable forwardings */ 874 } 875#endif 876 877 if (check_quietlogin(s, command)) 878 return; 879 880 display_loginmsg(); 881 882 do_motd(); 883} 884 885/* 886 * Display the message of the day. 887 */ 888void 889do_motd(void) 890{ 891 FILE *f; 892 char buf[256]; 893#ifdef HAVE_LOGIN_CAP 894 const char *fname; 895#endif 896 897#ifdef HAVE_LOGIN_CAP 898 fname = login_getcapstr(lc, "copyright", NULL, NULL); 899 if (fname != NULL && (f = fopen(fname, "r")) != NULL) { 900 while (fgets(buf, sizeof(buf), f) != NULL) 901 fputs(buf, stdout); 902 fclose(f); 903 } else 904#endif /* HAVE_LOGIN_CAP */ 905 (void)printf("%s\n\t%s %s\n", 906 "Copyright (c) 1980, 1983, 1986, 1988, 1990, 1991, 1993, 1994", 907 "The Regents of the University of California. ", 908 "All rights reserved."); 909 910 (void)printf("\n"); 911 912 if (options.print_motd) { 913#ifdef HAVE_LOGIN_CAP 914 f = fopen(login_getcapstr(lc, "welcome", "/etc/motd", 915 "/etc/motd"), "r"); 916#else 917 f = fopen("/etc/motd", "r"); 918#endif 919 if (f) { 920 while (fgets(buf, sizeof(buf), f)) 921 fputs(buf, stdout); 922 fclose(f); 923 } 924 } 925} 926 927 928/* 929 * Check for quiet login, either .hushlogin or command given. 930 */ 931int 932check_quietlogin(Session *s, const char *command) 933{ 934 char buf[256]; 935 struct passwd *pw = s->pw; 936 struct stat st; 937 938 /* Return 1 if .hushlogin exists or a command given. */ 939 if (command != NULL) 940 return 1; 941 snprintf(buf, sizeof(buf), "%.200s/.hushlogin", pw->pw_dir); 942#ifdef HAVE_LOGIN_CAP 943 if (login_getcapbool(lc, "hushlogin", 0) || stat(buf, &st) >= 0) 944 return 1; 945#else 946 if (stat(buf, &st) >= 0) 947 return 1; 948#endif 949 return 0; 950} 951 952/* 953 * Sets the value of the given variable in the environment. If the variable 954 * already exists, its value is overridden. 955 */ 956void 957child_set_env(char ***envp, u_int *envsizep, const char *name, 958 const char *value) 959{ 960 char **env; 961 u_int envsize; 962 u_int i, namelen; 963 964 /* 965 * If we're passed an uninitialized list, allocate a single null 966 * entry before continuing. 967 */ 968 if (*envp == NULL && *envsizep == 0) { 969 *envp = xmalloc(sizeof(char *)); 970 *envp[0] = NULL; 971 *envsizep = 1; 972 } 973 974 /* 975 * Find the slot where the value should be stored. If the variable 976 * already exists, we reuse the slot; otherwise we append a new slot 977 * at the end of the array, expanding if necessary. 978 */ 979 env = *envp; 980 namelen = strlen(name); 981 for (i = 0; env[i]; i++) 982 if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=') 983 break; 984 if (env[i]) { 985 /* Reuse the slot. */ 986 xfree(env[i]); 987 } else { 988 /* New variable. Expand if necessary. */ 989 envsize = *envsizep; 990 if (i >= envsize - 1) { 991 if (envsize >= 1000) 992 fatal("child_set_env: too many env vars"); 993 envsize += 50; 994 env = (*envp) = xrealloc(env, envsize, sizeof(char *)); 995 *envsizep = envsize; 996 } 997 /* Need to set the NULL pointer at end of array beyond the new slot. */ 998 env[i + 1] = NULL; 999 } 1000 1001 /* Allocate space and format the variable in the appropriate slot. */ 1002 env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1); 1003 snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value); 1004} 1005 1006/* 1007 * Reads environment variables from the given file and adds/overrides them 1008 * into the environment. If the file does not exist, this does nothing. 1009 * Otherwise, it must consist of empty lines, comments (line starts with '#') 1010 * and assignments of the form name=value. No other forms are allowed. 1011 */ 1012static void 1013read_environment_file(char ***env, u_int *envsize, 1014 const char *filename) 1015{ 1016 FILE *f; 1017 char buf[4096]; 1018 char *cp, *value; 1019 u_int lineno = 0; 1020 1021 f = fopen(filename, "r"); 1022 if (!f) 1023 return; 1024 1025 while (fgets(buf, sizeof(buf), f)) { 1026 if (++lineno > 1000) 1027 fatal("Too many lines in environment file %s", filename); 1028 for (cp = buf; *cp == ' ' || *cp == '\t'; cp++) 1029 ; 1030 if (!*cp || *cp == '#' || *cp == '\n') 1031 continue; 1032 1033 cp[strcspn(cp, "\n")] = '\0'; 1034 1035 value = strchr(cp, '='); 1036 if (value == NULL) { 1037 fprintf(stderr, "Bad line %u in %.100s\n", lineno, 1038 filename); 1039 continue; 1040 } 1041 /* 1042 * Replace the equals sign by nul, and advance value to 1043 * the value string. 1044 */ 1045 *value = '\0'; 1046 value++; 1047 child_set_env(env, envsize, cp, value); 1048 } 1049 fclose(f); 1050} 1051 1052#ifdef HAVE_ETC_DEFAULT_LOGIN 1053/* 1054 * Return named variable from specified environment, or NULL if not present. 1055 */ 1056static char * 1057child_get_env(char **env, const char *name) 1058{ 1059 int i; 1060 size_t len; 1061 1062 len = strlen(name); 1063 for (i=0; env[i] != NULL; i++) 1064 if (strncmp(name, env[i], len) == 0 && env[i][len] == '=') 1065 return(env[i] + len + 1); 1066 return NULL; 1067} 1068 1069/* 1070 * Read /etc/default/login. 1071 * We pick up the PATH (or SUPATH for root) and UMASK. 1072 */ 1073static void 1074read_etc_default_login(char ***env, u_int *envsize, uid_t uid) 1075{ 1076 char **tmpenv = NULL, *var; 1077 u_int i, tmpenvsize = 0; 1078 u_long mask; 1079 1080 /* 1081 * We don't want to copy the whole file to the child's environment, 1082 * so we use a temporary environment and copy the variables we're 1083 * interested in. 1084 */ 1085 read_environment_file(&tmpenv, &tmpenvsize, "/etc/default/login"); 1086 1087 if (tmpenv == NULL) 1088 return; 1089 1090 if (uid == 0) 1091 var = child_get_env(tmpenv, "SUPATH"); 1092 else 1093 var = child_get_env(tmpenv, "PATH"); 1094 if (var != NULL) 1095 child_set_env(env, envsize, "PATH", var); 1096 1097 if ((var = child_get_env(tmpenv, "UMASK")) != NULL) 1098 if (sscanf(var, "%5lo", &mask) == 1) 1099 umask((mode_t)mask); 1100 1101 for (i = 0; tmpenv[i] != NULL; i++) 1102 xfree(tmpenv[i]); 1103 xfree(tmpenv); 1104} 1105#endif /* HAVE_ETC_DEFAULT_LOGIN */ 1106 1107void 1108copy_environment(char **source, char ***env, u_int *envsize) 1109{ 1110 char *var_name, *var_val; 1111 int i; 1112 1113 if (source == NULL) 1114 return; 1115 1116 for(i = 0; source[i] != NULL; i++) { 1117 var_name = xstrdup(source[i]); 1118 if ((var_val = strstr(var_name, "=")) == NULL) { 1119 xfree(var_name); 1120 continue; 1121 } 1122 *var_val++ = '\0'; 1123 1124 debug3("Copy environment: %s=%s", var_name, var_val); 1125 child_set_env(env, envsize, var_name, var_val); 1126 1127 xfree(var_name); 1128 } 1129} 1130 1131static char ** 1132do_setup_env(Session *s, const char *shell) 1133{ 1134 char buf[256]; 1135 u_int i, envsize; 1136 char **env, *laddr; 1137 struct passwd *pw = s->pw; 1138#ifndef HAVE_LOGIN_CAP 1139 char *path = NULL; 1140#else 1141 extern char **environ; 1142 char **senv, **var; 1143#endif 1144 1145 /* Initialize the environment. */ 1146 envsize = 100; 1147 env = xcalloc(envsize, sizeof(char *)); 1148 env[0] = NULL; 1149 1150#ifdef HAVE_CYGWIN 1151 /* 1152 * The Windows environment contains some setting which are 1153 * important for a running system. They must not be dropped. 1154 */ 1155 { 1156 char **p; 1157 1158 p = fetch_windows_environment(); 1159 copy_environment(p, &env, &envsize); 1160 free_windows_environment(p); 1161 } 1162#endif 1163 1164 if (getenv("TZ")) 1165 child_set_env(&env, &envsize, "TZ", getenv("TZ")); 1166 1167#ifdef GSSAPI 1168 /* Allow any GSSAPI methods that we've used to alter 1169 * the childs environment as they see fit 1170 */ 1171 ssh_gssapi_do_child(&env, &envsize); 1172#endif 1173 1174 if (!options.use_login) { 1175 /* Set basic environment. */ 1176 for (i = 0; i < s->num_env; i++) 1177 child_set_env(&env, &envsize, s->env[i].name, 1178 s->env[i].val); 1179 1180 child_set_env(&env, &envsize, "USER", pw->pw_name); 1181 child_set_env(&env, &envsize, "LOGNAME", pw->pw_name); 1182#ifdef _AIX 1183 child_set_env(&env, &envsize, "LOGIN", pw->pw_name); 1184#endif 1185 child_set_env(&env, &envsize, "HOME", pw->pw_dir); 1186 snprintf(buf, sizeof buf, "%.200s/%.50s", 1187 _PATH_MAILDIR, pw->pw_name); 1188 child_set_env(&env, &envsize, "MAIL", buf); 1189#ifdef HAVE_LOGIN_CAP 1190 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); 1191 child_set_env(&env, &envsize, "TERM", "su"); 1192 senv = environ; 1193 environ = xmalloc(sizeof(char *)); 1194 *environ = NULL; 1195 (void) setusercontext(lc, pw, pw->pw_uid, 1196 LOGIN_SETENV|LOGIN_SETPATH); 1197 copy_environment(environ, &env, &envsize); 1198 for (var = environ; *var != NULL; ++var) 1199 xfree(*var); 1200 xfree(environ); 1201 environ = senv; 1202#else /* HAVE_LOGIN_CAP */ 1203# ifndef HAVE_CYGWIN 1204 /* 1205 * There's no standard path on Windows. The path contains 1206 * important components pointing to the system directories, 1207 * needed for loading shared libraries. So the path better 1208 * remains intact here. 1209 */ 1210# ifdef HAVE_ETC_DEFAULT_LOGIN 1211 read_etc_default_login(&env, &envsize, pw->pw_uid); 1212 path = child_get_env(env, "PATH"); 1213# endif /* HAVE_ETC_DEFAULT_LOGIN */ 1214 if (path == NULL || *path == '\0') { 1215 child_set_env(&env, &envsize, "PATH", 1216 s->pw->pw_uid == 0 ? 1217 SUPERUSER_PATH : _PATH_STDPATH); 1218 } 1219# endif /* HAVE_CYGWIN */ 1220#endif /* HAVE_LOGIN_CAP */ 1221 1222 /* Normal systems set SHELL by default. */ 1223 child_set_env(&env, &envsize, "SHELL", shell); 1224 } 1225 1226 /* Set custom environment options from RSA authentication. */ 1227 if (!options.use_login) { 1228 while (custom_environment) { 1229 struct envstring *ce = custom_environment; 1230 char *str = ce->s; 1231 1232 for (i = 0; str[i] != '=' && str[i]; i++) 1233 ; 1234 if (str[i] == '=') { 1235 str[i] = 0; 1236 child_set_env(&env, &envsize, str, str + i + 1); 1237 } 1238 custom_environment = ce->next; 1239 xfree(ce->s); 1240 xfree(ce); 1241 } 1242 } 1243 1244 /* SSH_CLIENT deprecated */ 1245 snprintf(buf, sizeof buf, "%.50s %d %d", 1246 get_remote_ipaddr(), get_remote_port(), get_local_port()); 1247 child_set_env(&env, &envsize, "SSH_CLIENT", buf); 1248 1249 laddr = get_local_ipaddr(packet_get_connection_in()); 1250 snprintf(buf, sizeof buf, "%.50s %d %.50s %d", 1251 get_remote_ipaddr(), get_remote_port(), laddr, get_local_port()); 1252 xfree(laddr); 1253 child_set_env(&env, &envsize, "SSH_CONNECTION", buf); 1254 1255 if (s->ttyfd != -1) 1256 child_set_env(&env, &envsize, "SSH_TTY", s->tty); 1257 if (s->term) 1258 child_set_env(&env, &envsize, "TERM", s->term); 1259 if (s->display) 1260 child_set_env(&env, &envsize, "DISPLAY", s->display); 1261 if (original_command) 1262 child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND", 1263 original_command); 1264 1265#ifdef _UNICOS 1266 if (cray_tmpdir[0] != '\0') 1267 child_set_env(&env, &envsize, "TMPDIR", cray_tmpdir); 1268#endif /* _UNICOS */ 1269 1270 /* 1271 * Since we clear KRB5CCNAME at startup, if it's set now then it 1272 * must have been set by a native authentication method (eg AIX or 1273 * SIA), so copy it to the child. 1274 */ 1275 { 1276 char *cp; 1277 1278 if ((cp = getenv("KRB5CCNAME")) != NULL) 1279 child_set_env(&env, &envsize, "KRB5CCNAME", cp); 1280 } 1281 1282#ifdef _AIX 1283 { 1284 char *cp; 1285 1286 if ((cp = getenv("AUTHSTATE")) != NULL) 1287 child_set_env(&env, &envsize, "AUTHSTATE", cp); 1288 read_environment_file(&env, &envsize, "/etc/environment"); 1289 } 1290#endif 1291#ifdef KRB5 1292 if (s->authctxt->krb5_ccname) 1293 child_set_env(&env, &envsize, "KRB5CCNAME", 1294 s->authctxt->krb5_ccname); 1295#endif 1296#ifdef USE_PAM 1297 /* 1298 * Pull in any environment variables that may have 1299 * been set by PAM. 1300 */ 1301 if (options.use_pam) { 1302 char **p; 1303 1304 p = fetch_pam_child_environment(); 1305 copy_environment(p, &env, &envsize); 1306 free_pam_environment(p); 1307 1308 p = fetch_pam_environment(); 1309 copy_environment(p, &env, &envsize); 1310 free_pam_environment(p); 1311 } 1312#endif /* USE_PAM */ 1313 1314 if (auth_sock_name != NULL) 1315 child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME, 1316 auth_sock_name); 1317 1318 /* read $HOME/.ssh/environment. */ 1319 if (options.permit_user_env && !options.use_login) { 1320 snprintf(buf, sizeof buf, "%.200s/.ssh/environment", 1321 strcmp(pw->pw_dir, "/") ? pw->pw_dir : ""); 1322 read_environment_file(&env, &envsize, buf); 1323 } 1324 if (debug_flag) { 1325 /* dump the environment */ 1326 fprintf(stderr, "Environment:\n"); 1327 for (i = 0; env[i]; i++) 1328 fprintf(stderr, " %.200s\n", env[i]); 1329 } 1330 return env; 1331} 1332 1333/* 1334 * Run $HOME/.ssh/rc, /etc/ssh/sshrc, or xauth (whichever is found 1335 * first in this order). 1336 */ 1337static void 1338do_rc_files(Session *s, const char *shell) 1339{ 1340 FILE *f = NULL; 1341 char cmd[1024]; 1342 int do_xauth; 1343 struct stat st; 1344 1345 do_xauth = 1346 s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL; 1347 1348 /* ignore _PATH_SSH_USER_RC for subsystems and admin forced commands */ 1349 if (!s->is_subsystem && options.adm_forced_command == NULL && 1350 !no_user_rc && stat(_PATH_SSH_USER_RC, &st) >= 0) { 1351 snprintf(cmd, sizeof cmd, "%s -c '%s %s'", 1352 shell, _PATH_BSHELL, _PATH_SSH_USER_RC); 1353 if (debug_flag) 1354 fprintf(stderr, "Running %s\n", cmd); 1355 f = popen(cmd, "w"); 1356 if (f) { 1357 if (do_xauth) 1358 fprintf(f, "%s %s\n", s->auth_proto, 1359 s->auth_data); 1360 pclose(f); 1361 } else 1362 fprintf(stderr, "Could not run %s\n", 1363 _PATH_SSH_USER_RC); 1364 } else if (stat(_PATH_SSH_SYSTEM_RC, &st) >= 0) { 1365 if (debug_flag) 1366 fprintf(stderr, "Running %s %s\n", _PATH_BSHELL, 1367 _PATH_SSH_SYSTEM_RC); 1368 f = popen(_PATH_BSHELL " " _PATH_SSH_SYSTEM_RC, "w"); 1369 if (f) { 1370 if (do_xauth) 1371 fprintf(f, "%s %s\n", s->auth_proto, 1372 s->auth_data); 1373 pclose(f); 1374 } else 1375 fprintf(stderr, "Could not run %s\n", 1376 _PATH_SSH_SYSTEM_RC); 1377 } else if (do_xauth && options.xauth_location != NULL) { 1378 /* Add authority data to .Xauthority if appropriate. */ 1379 if (debug_flag) { 1380 fprintf(stderr, 1381 "Running %.500s remove %.100s\n", 1382 options.xauth_location, s->auth_display); 1383 fprintf(stderr, 1384 "%.500s add %.100s %.100s %.100s\n", 1385 options.xauth_location, s->auth_display, 1386 s->auth_proto, s->auth_data); 1387 } 1388 snprintf(cmd, sizeof cmd, "%s -q -", 1389 options.xauth_location); 1390 f = popen(cmd, "w"); 1391 if (f) { 1392 fprintf(f, "remove %s\n", 1393 s->auth_display); 1394 fprintf(f, "add %s %s %s\n", 1395 s->auth_display, s->auth_proto, 1396 s->auth_data); 1397 pclose(f); 1398 } else { 1399 fprintf(stderr, "Could not run %s\n", 1400 cmd); 1401 } 1402 } 1403} 1404 1405static void 1406do_nologin(struct passwd *pw) 1407{ 1408 FILE *f = NULL; 1409 char buf[1024]; 1410 1411#ifdef HAVE_LOGIN_CAP 1412 if (!login_getcapbool(lc, "ignorenologin", 0) && pw->pw_uid) 1413 f = fopen(login_getcapstr(lc, "nologin", _PATH_NOLOGIN, 1414 _PATH_NOLOGIN), "r"); 1415#else 1416 if (pw->pw_uid) 1417 f = fopen(_PATH_NOLOGIN, "r"); 1418#endif 1419 if (f) { 1420 /* /etc/nologin exists. Print its contents and exit. */ 1421 logit("User %.100s not allowed because %s exists", 1422 pw->pw_name, _PATH_NOLOGIN); 1423 while (fgets(buf, sizeof(buf), f)) 1424 fputs(buf, stderr); 1425 fclose(f); 1426 fflush(NULL); 1427 exit(254); 1428 } 1429} 1430 1431/* 1432 * Chroot into a directory after checking it for safety: all path components 1433 * must be root-owned directories with strict permissions. 1434 */ 1435static void 1436safely_chroot(const char *path, uid_t uid) 1437{ 1438 const char *cp; 1439 char component[MAXPATHLEN]; 1440 struct stat st; 1441 1442 if (*path != '/') 1443 fatal("chroot path does not begin at root"); 1444 if (strlen(path) >= sizeof(component)) 1445 fatal("chroot path too long"); 1446 1447 /* 1448 * Descend the path, checking that each component is a 1449 * root-owned directory with strict permissions. 1450 */ 1451 for (cp = path; cp != NULL;) { 1452 if ((cp = strchr(cp, '/')) == NULL) 1453 strlcpy(component, path, sizeof(component)); 1454 else { 1455 cp++; 1456 memcpy(component, path, cp - path); 1457 component[cp - path] = '\0'; 1458 } 1459 1460 debug3("%s: checking '%s'", __func__, component); 1461 1462 if (stat(component, &st) != 0) 1463 fatal("%s: stat(\"%s\"): %s", __func__, 1464 component, strerror(errno)); 1465 if (st.st_uid != 0 || (st.st_mode & 022) != 0) 1466 fatal("bad ownership or modes for chroot " 1467 "directory %s\"%s\"", 1468 cp == NULL ? "" : "component ", component); 1469 if (!S_ISDIR(st.st_mode)) 1470 fatal("chroot path %s\"%s\" is not a directory", 1471 cp == NULL ? "" : "component ", component); 1472 1473 } 1474 1475 if (chdir(path) == -1) 1476 fatal("Unable to chdir to chroot path \"%s\": " 1477 "%s", path, strerror(errno)); 1478 if (chroot(path) == -1) 1479 fatal("chroot(\"%s\"): %s", path, strerror(errno)); 1480 if (chdir("/") == -1) 1481 fatal("%s: chdir(/) after chroot: %s", 1482 __func__, strerror(errno)); 1483 verbose("Changed root directory to \"%s\"", path); 1484} 1485 1486/* Set login name, uid, gid, and groups. */ 1487void 1488do_setusercontext(struct passwd *pw) 1489{ 1490 char *chroot_path, *tmp; 1491 1492#ifdef WITH_SELINUX 1493 /* Cache selinux status for later use */ 1494 (void)ssh_selinux_enabled(); 1495#endif 1496 1497#ifndef HAVE_CYGWIN 1498 if (getuid() == 0 || geteuid() == 0) 1499#endif /* HAVE_CYGWIN */ 1500 { 1501 1502#ifdef HAVE_SETPCRED 1503 if (setpcred(pw->pw_name, (char **)NULL) == -1) 1504 fatal("Failed to set process credentials"); 1505#endif /* HAVE_SETPCRED */ 1506#ifdef HAVE_LOGIN_CAP 1507# ifdef __bsdi__ 1508 setpgid(0, 0); 1509# endif 1510# ifdef USE_PAM 1511 if (options.use_pam) { 1512 do_pam_setcred(use_privsep); 1513 } 1514# endif /* USE_PAM */ 1515 if (setusercontext(lc, pw, pw->pw_uid, 1516 (LOGIN_SETALL & ~(LOGIN_SETENV|LOGIN_SETPATH|LOGIN_SETUSER))) < 0) { 1517 perror("unable to set user context"); 1518 exit(1); 1519 } 1520#else 1521# if defined(HAVE_GETLUID) && defined(HAVE_SETLUID) 1522 /* Sets login uid for accounting */ 1523 if (getluid() == -1 && setluid(pw->pw_uid) == -1) 1524 error("setluid: %s", strerror(errno)); 1525# endif /* defined(HAVE_GETLUID) && defined(HAVE_SETLUID) */ 1526 1527 if (setlogin(pw->pw_name) < 0) 1528 error("setlogin failed: %s", strerror(errno)); 1529 if (setgid(pw->pw_gid) < 0) { 1530 perror("setgid"); 1531 exit(1); 1532 } 1533 /* Initialize the group list. */ 1534 if (initgroups(pw->pw_name, pw->pw_gid) < 0) { 1535 perror("initgroups"); 1536 exit(1); 1537 } 1538 endgrent(); 1539# ifdef USE_PAM 1540 /* 1541 * PAM credentials may take the form of supplementary groups. 1542 * These will have been wiped by the above initgroups() call. 1543 * Reestablish them here. 1544 */ 1545 if (options.use_pam) { 1546 do_pam_setcred(use_privsep); 1547 } 1548# endif /* USE_PAM */ 1549# if defined(WITH_IRIX_PROJECT) || defined(WITH_IRIX_JOBS) || defined(WITH_IRIX_ARRAY) 1550 irix_setusercontext(pw); 1551# endif /* defined(WITH_IRIX_PROJECT) || defined(WITH_IRIX_JOBS) || defined(WITH_IRIX_ARRAY) */ 1552# ifdef _AIX 1553 aix_usrinfo(pw); 1554# endif /* _AIX */ 1555# ifdef USE_LIBIAF 1556 if (set_id(pw->pw_name) != 0) { 1557 exit(1); 1558 } 1559# endif /* USE_LIBIAF */ 1560#endif 1561 1562 if (options.chroot_directory != NULL && 1563 strcasecmp(options.chroot_directory, "none") != 0) { 1564 tmp = tilde_expand_filename(options.chroot_directory, 1565 pw->pw_uid); 1566 chroot_path = percent_expand(tmp, "h", pw->pw_dir, 1567 "u", pw->pw_name, (char *)NULL); 1568 safely_chroot(chroot_path, pw->pw_uid); 1569 free(tmp); 1570 free(chroot_path); 1571 } 1572 1573#ifdef HAVE_LOGIN_CAP 1574 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUSER) < 0) { 1575 perror("unable to set user context (setuser)"); 1576 exit(1); 1577 } 1578#else 1579 /* Permanently switch to the desired uid. */ 1580 permanently_set_uid(pw); 1581#endif 1582 } 1583 1584#ifdef HAVE_CYGWIN 1585 if (is_winnt) 1586#endif 1587 if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) 1588 fatal("Failed to set uids to %u.", (u_int) pw->pw_uid); 1589 1590#ifdef WITH_SELINUX 1591 ssh_selinux_setup_exec_context(pw->pw_name); 1592#endif 1593} 1594 1595static void 1596do_pwchange(Session *s) 1597{ 1598 fflush(NULL); 1599 fprintf(stderr, "WARNING: Your password has expired.\n"); 1600 if (s->ttyfd != -1) { 1601 fprintf(stderr, 1602 "You must change your password now and login again!\n"); 1603#ifdef PASSWD_NEEDS_USERNAME 1604 execl(_PATH_PASSWD_PROG, "passwd", s->pw->pw_name, 1605 (char *)NULL); 1606#else 1607 execl(_PATH_PASSWD_PROG, "passwd", (char *)NULL); 1608#endif 1609 perror("passwd"); 1610 } else { 1611 fprintf(stderr, 1612 "Password change required but no TTY available.\n"); 1613 } 1614 exit(1); 1615} 1616 1617static void 1618launch_login(struct passwd *pw, const char *hostname) 1619{ 1620 /* Launch login(1). */ 1621 1622 execl(LOGIN_PROGRAM, "login", "-h", hostname, 1623#ifdef xxxLOGIN_NEEDS_TERM 1624 (s->term ? s->term : "unknown"), 1625#endif /* LOGIN_NEEDS_TERM */ 1626#ifdef LOGIN_NO_ENDOPT 1627 "-p", "-f", pw->pw_name, (char *)NULL); 1628#else 1629 "-p", "-f", "--", pw->pw_name, (char *)NULL); 1630#endif 1631 1632 /* Login couldn't be executed, die. */ 1633 1634 perror("login"); 1635 exit(1); 1636} 1637 1638static void 1639child_close_fds(void) 1640{ 1641 int i; 1642 1643 if (packet_get_connection_in() == packet_get_connection_out()) 1644 close(packet_get_connection_in()); 1645 else { 1646 close(packet_get_connection_in()); 1647 close(packet_get_connection_out()); 1648 } 1649 /* 1650 * Close all descriptors related to channels. They will still remain 1651 * open in the parent. 1652 */ 1653 /* XXX better use close-on-exec? -markus */ 1654 channel_close_all(); 1655 1656 /* 1657 * Close any extra file descriptors. Note that there may still be 1658 * descriptors left by system functions. They will be closed later. 1659 */ 1660 endpwent(); 1661 1662 /* 1663 * Close any extra open file descriptors so that we don't have them 1664 * hanging around in clients. Note that we want to do this after 1665 * initgroups, because at least on Solaris 2.3 it leaves file 1666 * descriptors open. 1667 */ 1668 for (i = 3; i < 64; i++) 1669 close(i); 1670} 1671 1672/* 1673 * Performs common processing for the child, such as setting up the 1674 * environment, closing extra file descriptors, setting the user and group 1675 * ids, and executing the command or shell. 1676 */ 1677#define ARGV_MAX 10 1678void 1679do_child(Session *s, const char *command) 1680{ 1681 extern char **environ; 1682 char **env; 1683 char *argv[ARGV_MAX]; 1684 const char *shell, *shell0, *hostname = NULL; 1685 struct passwd *pw = s->pw; 1686 int r = 0; 1687 1688 /* remove hostkey from the child's memory */ 1689 destroy_sensitive_data(); 1690 1691 /* Force a password change */ 1692 if (s->authctxt->force_pwchange) { 1693 do_setusercontext(pw); 1694 child_close_fds(); 1695 do_pwchange(s); 1696 exit(1); 1697 } 1698 1699 /* login(1) is only called if we execute the login shell */ 1700 if (options.use_login && command != NULL) 1701 options.use_login = 0; 1702 1703#ifdef _UNICOS 1704 cray_setup(pw->pw_uid, pw->pw_name, command); 1705#endif /* _UNICOS */ 1706 1707 /* 1708 * Login(1) does this as well, and it needs uid 0 for the "-h" 1709 * switch, so we let login(1) to this for us. 1710 */ 1711 if (!options.use_login) { 1712#ifdef HAVE_OSF_SIA 1713 session_setup_sia(pw, s->ttyfd == -1 ? NULL : s->tty); 1714 if (!check_quietlogin(s, command)) 1715 do_motd(); 1716#else /* HAVE_OSF_SIA */ 1717 /* When PAM is enabled we rely on it to do the nologin check */ 1718 if (!options.use_pam) 1719 do_nologin(pw); 1720 do_setusercontext(pw); 1721 /* 1722 * PAM session modules in do_setusercontext may have 1723 * generated messages, so if this in an interactive 1724 * login then display them too. 1725 */ 1726 if (!check_quietlogin(s, command)) 1727 display_loginmsg(); 1728#endif /* HAVE_OSF_SIA */ 1729 } 1730 1731#ifdef USE_PAM 1732 if (options.use_pam && !options.use_login && !is_pam_session_open()) { 1733 debug3("PAM session not opened, exiting"); 1734 display_loginmsg(); 1735 exit(254); 1736 } 1737#endif 1738 1739 /* 1740 * Get the shell from the password data. An empty shell field is 1741 * legal, and means /bin/sh. 1742 */ 1743 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; 1744 1745 /* 1746 * Make sure $SHELL points to the shell from the password file, 1747 * even if shell is overridden from login.conf 1748 */ 1749 env = do_setup_env(s, shell); 1750 1751#ifdef HAVE_LOGIN_CAP 1752 shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell); 1753#endif 1754 1755 /* we have to stash the hostname before we close our socket. */ 1756 if (options.use_login) 1757 hostname = get_remote_name_or_ip(utmp_len, 1758 options.use_dns); 1759 /* 1760 * Close the connection descriptors; note that this is the child, and 1761 * the server will still have the socket open, and it is important 1762 * that we do not shutdown it. Note that the descriptors cannot be 1763 * closed before building the environment, as we call 1764 * get_remote_ipaddr there. 1765 */ 1766 child_close_fds(); 1767 1768 /* 1769 * Must take new environment into use so that .ssh/rc, 1770 * /etc/ssh/sshrc and xauth are run in the proper environment. 1771 */ 1772 environ = env; 1773 1774#if defined(KRB5) && defined(USE_AFS) 1775 /* 1776 * At this point, we check to see if AFS is active and if we have 1777 * a valid Kerberos 5 TGT. If so, it seems like a good idea to see 1778 * if we can (and need to) extend the ticket into an AFS token. If 1779 * we don't do this, we run into potential problems if the user's 1780 * home directory is in AFS and it's not world-readable. 1781 */ 1782 1783 if (options.kerberos_get_afs_token && k_hasafs() && 1784 (s->authctxt->krb5_ctx != NULL)) { 1785 char cell[64]; 1786 1787 debug("Getting AFS token"); 1788 1789 k_setpag(); 1790 1791 if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0) 1792 krb5_afslog(s->authctxt->krb5_ctx, 1793 s->authctxt->krb5_fwd_ccache, cell, NULL); 1794 1795 krb5_afslog_home(s->authctxt->krb5_ctx, 1796 s->authctxt->krb5_fwd_ccache, NULL, NULL, pw->pw_dir); 1797 } 1798#endif 1799 1800 /* Change current directory to the user's home directory. */ 1801 if (chdir(pw->pw_dir) < 0) { 1802 /* Suppress missing homedir warning for chroot case */ 1803#ifdef HAVE_LOGIN_CAP 1804 r = login_getcapbool(lc, "requirehome", 0); 1805#endif 1806 if (r || options.chroot_directory == NULL) 1807 fprintf(stderr, "Could not chdir to home " 1808 "directory %s: %s\n", pw->pw_dir, 1809 strerror(errno)); 1810 if (r) 1811 exit(1); 1812 } 1813 1814 closefrom(STDERR_FILENO + 1); 1815 1816 if (!options.use_login) 1817 do_rc_files(s, shell); 1818 1819 /* restore SIGPIPE for child */ 1820 signal(SIGPIPE, SIG_DFL); 1821 1822 if (s->is_subsystem == SUBSYSTEM_INT_SFTP) { 1823 extern int optind, optreset; 1824 int i; 1825 char *p, *args; 1826 1827 setproctitle("%s@internal-sftp-server", s->pw->pw_name); 1828 args = xstrdup(command ? command : "sftp-server"); 1829 for (i = 0, (p = strtok(args, " ")); p; (p = strtok(NULL, " "))) 1830 if (i < ARGV_MAX - 1) 1831 argv[i++] = p; 1832 argv[i] = NULL; 1833 optind = optreset = 1; 1834 __progname = argv[0]; 1835 exit(sftp_server_main(i, argv, s->pw)); 1836 } 1837 1838 if (options.use_login) { 1839 launch_login(pw, hostname); 1840 /* NEVERREACHED */ 1841 } 1842 1843 /* Get the last component of the shell name. */ 1844 if ((shell0 = strrchr(shell, '/')) != NULL) 1845 shell0++; 1846 else 1847 shell0 = shell; 1848 1849 /* 1850 * If we have no command, execute the shell. In this case, the shell 1851 * name to be passed in argv[0] is preceded by '-' to indicate that 1852 * this is a login shell. 1853 */ 1854 if (!command) { 1855 char argv0[256]; 1856 1857 /* Start the shell. Set initial character to '-'. */ 1858 argv0[0] = '-'; 1859 1860 if (strlcpy(argv0 + 1, shell0, sizeof(argv0) - 1) 1861 >= sizeof(argv0) - 1) { 1862 errno = EINVAL; 1863 perror(shell); 1864 exit(1); 1865 } 1866 1867 /* Execute the shell. */ 1868 argv[0] = argv0; 1869 argv[1] = NULL; 1870 execve(shell, argv, env); 1871 1872 /* Executing the shell failed. */ 1873 perror(shell); 1874 exit(1); 1875 } 1876 /* 1877 * Execute the command using the user's shell. This uses the -c 1878 * option to execute the command. 1879 */ 1880 argv[0] = (char *) shell0; 1881 argv[1] = "-c"; 1882 argv[2] = (char *) command; 1883 argv[3] = NULL; 1884 execve(shell, argv, env); 1885 perror(shell); 1886 exit(1); 1887} 1888 1889void 1890session_unused(int id) 1891{ 1892 debug3("%s: session id %d unused", __func__, id); 1893 if (id >= options.max_sessions || 1894 id >= sessions_nalloc) { 1895 fatal("%s: insane session id %d (max %d nalloc %d)", 1896 __func__, id, options.max_sessions, sessions_nalloc); 1897 } 1898 bzero(&sessions[id], sizeof(*sessions)); 1899 sessions[id].self = id; 1900 sessions[id].used = 0; 1901 sessions[id].chanid = -1; 1902 sessions[id].ptyfd = -1; 1903 sessions[id].ttyfd = -1; 1904 sessions[id].ptymaster = -1; 1905 sessions[id].x11_chanids = NULL; 1906 sessions[id].next_unused = sessions_first_unused; 1907 sessions_first_unused = id; 1908} 1909 1910Session * 1911session_new(void) 1912{ 1913 Session *s, *tmp; 1914 1915 if (sessions_first_unused == -1) { 1916 if (sessions_nalloc >= options.max_sessions) 1917 return NULL; 1918 debug2("%s: allocate (allocated %d max %d)", 1919 __func__, sessions_nalloc, options.max_sessions); 1920 tmp = xrealloc(sessions, sessions_nalloc + 1, 1921 sizeof(*sessions)); 1922 if (tmp == NULL) { 1923 error("%s: cannot allocate %d sessions", 1924 __func__, sessions_nalloc + 1); 1925 return NULL; 1926 } 1927 sessions = tmp; 1928 session_unused(sessions_nalloc++); 1929 } 1930 1931 if (sessions_first_unused >= sessions_nalloc || 1932 sessions_first_unused < 0) { 1933 fatal("%s: insane first_unused %d max %d nalloc %d", 1934 __func__, sessions_first_unused, options.max_sessions, 1935 sessions_nalloc); 1936 } 1937 1938 s = &sessions[sessions_first_unused]; 1939 if (s->used) { 1940 fatal("%s: session %d already used", 1941 __func__, sessions_first_unused); 1942 } 1943 sessions_first_unused = s->next_unused; 1944 s->used = 1; 1945 s->next_unused = -1; 1946 debug("session_new: session %d", s->self); 1947 1948 return s; 1949} 1950 1951static void 1952session_dump(void) 1953{ 1954 int i; 1955 for (i = 0; i < sessions_nalloc; i++) { 1956 Session *s = &sessions[i]; 1957 1958 debug("dump: used %d next_unused %d session %d %p " 1959 "channel %d pid %ld", 1960 s->used, 1961 s->next_unused, 1962 s->self, 1963 s, 1964 s->chanid, 1965 (long)s->pid); 1966 } 1967} 1968 1969int 1970session_open(Authctxt *authctxt, int chanid) 1971{ 1972 Session *s = session_new(); 1973 debug("session_open: channel %d", chanid); 1974 if (s == NULL) { 1975 error("no more sessions"); 1976 return 0; 1977 } 1978 s->authctxt = authctxt; 1979 s->pw = authctxt->pw; 1980 if (s->pw == NULL || !authctxt->valid) 1981 fatal("no user for session %d", s->self); 1982 debug("session_open: session %d: link with channel %d", s->self, chanid); 1983 s->chanid = chanid; 1984 return 1; 1985} 1986 1987Session * 1988session_by_tty(char *tty) 1989{ 1990 int i; 1991 for (i = 0; i < sessions_nalloc; i++) { 1992 Session *s = &sessions[i]; 1993 if (s->used && s->ttyfd != -1 && strcmp(s->tty, tty) == 0) { 1994 debug("session_by_tty: session %d tty %s", i, tty); 1995 return s; 1996 } 1997 } 1998 debug("session_by_tty: unknown tty %.100s", tty); 1999 session_dump(); 2000 return NULL; 2001} 2002 2003static Session * 2004session_by_channel(int id) 2005{ 2006 int i; 2007 for (i = 0; i < sessions_nalloc; i++) { 2008 Session *s = &sessions[i]; 2009 if (s->used && s->chanid == id) { 2010 debug("session_by_channel: session %d channel %d", 2011 i, id); 2012 return s; 2013 } 2014 } 2015 debug("session_by_channel: unknown channel %d", id); 2016 session_dump(); 2017 return NULL; 2018} 2019 2020static Session * 2021session_by_x11_channel(int id) 2022{ 2023 int i, j; 2024 2025 for (i = 0; i < sessions_nalloc; i++) { 2026 Session *s = &sessions[i]; 2027 2028 if (s->x11_chanids == NULL || !s->used) 2029 continue; 2030 for (j = 0; s->x11_chanids[j] != -1; j++) { 2031 if (s->x11_chanids[j] == id) { 2032 debug("session_by_x11_channel: session %d " 2033 "channel %d", s->self, id); 2034 return s; 2035 } 2036 } 2037 } 2038 debug("session_by_x11_channel: unknown channel %d", id); 2039 session_dump(); 2040 return NULL; 2041} 2042 2043static Session * 2044session_by_pid(pid_t pid) 2045{ 2046 int i; 2047 debug("session_by_pid: pid %ld", (long)pid); 2048 for (i = 0; i < sessions_nalloc; i++) { 2049 Session *s = &sessions[i]; 2050 if (s->used && s->pid == pid) 2051 return s; 2052 } 2053 error("session_by_pid: unknown pid %ld", (long)pid); 2054 session_dump(); 2055 return NULL; 2056} 2057 2058static int 2059session_window_change_req(Session *s) 2060{ 2061 s->col = packet_get_int(); 2062 s->row = packet_get_int(); 2063 s->xpixel = packet_get_int(); 2064 s->ypixel = packet_get_int(); 2065 packet_check_eom(); 2066 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 2067 return 1; 2068} 2069 2070static int 2071session_pty_req(Session *s) 2072{ 2073 u_int len; 2074 int n_bytes; 2075 2076 if (no_pty_flag) { 2077 debug("Allocating a pty not permitted for this authentication."); 2078 return 0; 2079 } 2080 if (s->ttyfd != -1) { 2081 packet_disconnect("Protocol error: you already have a pty."); 2082 return 0; 2083 } 2084 2085 s->term = packet_get_string(&len); 2086 2087 if (compat20) { 2088 s->col = packet_get_int(); 2089 s->row = packet_get_int(); 2090 } else { 2091 s->row = packet_get_int(); 2092 s->col = packet_get_int(); 2093 } 2094 s->xpixel = packet_get_int(); 2095 s->ypixel = packet_get_int(); 2096 2097 if (strcmp(s->term, "") == 0) { 2098 xfree(s->term); 2099 s->term = NULL; 2100 } 2101 2102 /* Allocate a pty and open it. */ 2103 debug("Allocating pty."); 2104 if (!PRIVSEP(pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, 2105 sizeof(s->tty)))) { 2106 if (s->term) 2107 xfree(s->term); 2108 s->term = NULL; 2109 s->ptyfd = -1; 2110 s->ttyfd = -1; 2111 error("session_pty_req: session %d alloc failed", s->self); 2112 return 0; 2113 } 2114 debug("session_pty_req: session %d alloc %s", s->self, s->tty); 2115 2116 /* for SSH1 the tty modes length is not given */ 2117 if (!compat20) 2118 n_bytes = packet_remaining(); 2119 tty_parse_modes(s->ttyfd, &n_bytes); 2120 2121 if (!use_privsep) 2122 pty_setowner(s->pw, s->tty); 2123 2124 /* Set window size from the packet. */ 2125 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 2126 2127 packet_check_eom(); 2128 session_proctitle(s); 2129 return 1; 2130} 2131 2132static int 2133session_subsystem_req(Session *s) 2134{ 2135 struct stat st; 2136 u_int len; 2137 int success = 0; 2138 char *prog, *cmd, *subsys = packet_get_string(&len); 2139 u_int i; 2140 2141 packet_check_eom(); 2142 logit("subsystem request for %.100s", subsys); 2143 2144 for (i = 0; i < options.num_subsystems; i++) { 2145 if (strcmp(subsys, options.subsystem_name[i]) == 0) { 2146 prog = options.subsystem_command[i]; 2147 cmd = options.subsystem_args[i]; 2148 if (!strcmp(INTERNAL_SFTP_NAME, prog)) { 2149 s->is_subsystem = SUBSYSTEM_INT_SFTP; 2150 } else if (stat(prog, &st) < 0) { 2151 error("subsystem: cannot stat %s: %s", prog, 2152 strerror(errno)); 2153 break; 2154 } else { 2155 s->is_subsystem = SUBSYSTEM_EXT; 2156 } 2157 debug("subsystem: exec() %s", cmd); 2158 success = do_exec(s, cmd) == 0; 2159 break; 2160 } 2161 } 2162 2163 if (!success) 2164 logit("subsystem request for %.100s failed, subsystem not found", 2165 subsys); 2166 2167 xfree(subsys); 2168 return success; 2169} 2170 2171static int 2172session_x11_req(Session *s) 2173{ 2174 int success; 2175 2176 if (s->auth_proto != NULL || s->auth_data != NULL) { 2177 error("session_x11_req: session %d: " 2178 "x11 forwarding already active", s->self); 2179 return 0; 2180 } 2181 s->single_connection = packet_get_char(); 2182 s->auth_proto = packet_get_string(NULL); 2183 s->auth_data = packet_get_string(NULL); 2184 s->screen = packet_get_int(); 2185 packet_check_eom(); 2186 2187 success = session_setup_x11fwd(s); 2188 if (!success) { 2189 xfree(s->auth_proto); 2190 xfree(s->auth_data); 2191 s->auth_proto = NULL; 2192 s->auth_data = NULL; 2193 } 2194 return success; 2195} 2196 2197static int 2198session_shell_req(Session *s) 2199{ 2200 packet_check_eom(); 2201 return do_exec(s, NULL) == 0; 2202} 2203 2204static int 2205session_exec_req(Session *s) 2206{ 2207 u_int len, success; 2208 2209 char *command = packet_get_string(&len); 2210 packet_check_eom(); 2211 success = do_exec(s, command) == 0; 2212 xfree(command); 2213 return success; 2214} 2215 2216static int 2217session_break_req(Session *s) 2218{ 2219 2220 packet_get_int(); /* ignored */ 2221 packet_check_eom(); 2222 2223 if (s->ttyfd == -1 || tcsendbreak(s->ttyfd, 0) < 0) 2224 return 0; 2225 return 1; 2226} 2227 2228static int 2229session_env_req(Session *s) 2230{ 2231 char *name, *val; 2232 u_int name_len, val_len, i; 2233 2234 name = packet_get_string(&name_len); 2235 val = packet_get_string(&val_len); 2236 packet_check_eom(); 2237 2238 /* Don't set too many environment variables */ 2239 if (s->num_env > 128) { 2240 debug2("Ignoring env request %s: too many env vars", name); 2241 goto fail; 2242 } 2243 2244 for (i = 0; i < options.num_accept_env; i++) { 2245 if (match_pattern(name, options.accept_env[i])) { 2246 debug2("Setting env %d: %s=%s", s->num_env, name, val); 2247 s->env = xrealloc(s->env, s->num_env + 1, 2248 sizeof(*s->env)); 2249 s->env[s->num_env].name = name; 2250 s->env[s->num_env].val = val; 2251 s->num_env++; 2252 return (1); 2253 } 2254 } 2255 debug2("Ignoring env request %s: disallowed name", name); 2256 2257 fail: 2258 xfree(name); 2259 xfree(val); 2260 return (0); 2261} 2262 2263static int 2264session_auth_agent_req(Session *s) 2265{ 2266 static int called = 0; 2267 packet_check_eom(); 2268 if (no_agent_forwarding_flag || !options.allow_agent_forwarding) { 2269 debug("session_auth_agent_req: no_agent_forwarding_flag"); 2270 return 0; 2271 } 2272 if (called) { 2273 return 0; 2274 } else { 2275 called = 1; 2276 return auth_input_request_forwarding(s->pw); 2277 } 2278} 2279 2280int 2281session_input_channel_req(Channel *c, const char *rtype) 2282{ 2283 int success = 0; 2284 Session *s; 2285 2286 if ((s = session_by_channel(c->self)) == NULL) { 2287 logit("session_input_channel_req: no session %d req %.100s", 2288 c->self, rtype); 2289 return 0; 2290 } 2291 debug("session_input_channel_req: session %d req %s", s->self, rtype); 2292 2293 /* 2294 * a session is in LARVAL state until a shell, a command 2295 * or a subsystem is executed 2296 */ 2297 if (c->type == SSH_CHANNEL_LARVAL) { 2298 if (strcmp(rtype, "shell") == 0) { 2299 success = session_shell_req(s); 2300 } else if (strcmp(rtype, "exec") == 0) { 2301 success = session_exec_req(s); 2302 } else if (strcmp(rtype, "pty-req") == 0) { 2303 success = session_pty_req(s); 2304 } else if (strcmp(rtype, "x11-req") == 0) { 2305 success = session_x11_req(s); 2306 } else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) { 2307 success = session_auth_agent_req(s); 2308 } else if (strcmp(rtype, "subsystem") == 0) { 2309 success = session_subsystem_req(s); 2310 } else if (strcmp(rtype, "env") == 0) { 2311 success = session_env_req(s); 2312 } 2313 } 2314 if (strcmp(rtype, "window-change") == 0) { 2315 success = session_window_change_req(s); 2316 } else if (strcmp(rtype, "break") == 0) { 2317 success = session_break_req(s); 2318 } 2319 2320 return success; 2321} 2322 2323void 2324session_set_fds(Session *s, int fdin, int fdout, int fderr, int is_tty) 2325{ 2326 if (!compat20) 2327 fatal("session_set_fds: called for proto != 2.0"); 2328 /* 2329 * now that have a child and a pipe to the child, 2330 * we can activate our channel and register the fd's 2331 */ 2332 if (s->chanid == -1) 2333 fatal("no channel for session %d", s->self); 2334 channel_set_fds(s->chanid, 2335 fdout, fdin, fderr, 2336 fderr == -1 ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ, 2337 1, is_tty, CHAN_SES_WINDOW_DEFAULT); 2338} 2339 2340/* 2341 * Function to perform pty cleanup. Also called if we get aborted abnormally 2342 * (e.g., due to a dropped connection). 2343 */ 2344void 2345session_pty_cleanup2(Session *s) 2346{ 2347 if (s == NULL) { 2348 error("session_pty_cleanup: no session"); 2349 return; 2350 } 2351 if (s->ttyfd == -1) 2352 return; 2353 2354 debug("session_pty_cleanup: session %d release %s", s->self, s->tty); 2355 2356 /* Record that the user has logged out. */ 2357 if (s->pid != 0) 2358 record_logout(s->pid, s->tty, s->pw->pw_name); 2359 2360 /* Release the pseudo-tty. */ 2361 if (getuid() == 0) 2362 pty_release(s->tty); 2363 2364 /* 2365 * Close the server side of the socket pairs. We must do this after 2366 * the pty cleanup, so that another process doesn't get this pty 2367 * while we're still cleaning up. 2368 */ 2369 if (s->ptymaster != -1 && close(s->ptymaster) < 0) 2370 error("close(s->ptymaster/%d): %s", 2371 s->ptymaster, strerror(errno)); 2372 2373 /* unlink pty from session */ 2374 s->ttyfd = -1; 2375} 2376 2377void 2378session_pty_cleanup(Session *s) 2379{ 2380 PRIVSEP(session_pty_cleanup2(s)); 2381} 2382 2383static char * 2384sig2name(int sig) 2385{ 2386#define SSH_SIG(x) if (sig == SIG ## x) return #x 2387 SSH_SIG(ABRT); 2388 SSH_SIG(ALRM); 2389 SSH_SIG(FPE); 2390 SSH_SIG(HUP); 2391 SSH_SIG(ILL); 2392 SSH_SIG(INT); 2393 SSH_SIG(KILL); 2394 SSH_SIG(PIPE); 2395 SSH_SIG(QUIT); 2396 SSH_SIG(SEGV); 2397 SSH_SIG(TERM); 2398 SSH_SIG(USR1); 2399 SSH_SIG(USR2); 2400#undef SSH_SIG 2401 return "SIG@openssh.com"; 2402} 2403 2404static void 2405session_close_x11(int id) 2406{ 2407 Channel *c; 2408 2409 if ((c = channel_by_id(id)) == NULL) { 2410 debug("session_close_x11: x11 channel %d missing", id); 2411 } else { 2412 /* Detach X11 listener */ 2413 debug("session_close_x11: detach x11 channel %d", id); 2414 channel_cancel_cleanup(id); 2415 if (c->ostate != CHAN_OUTPUT_CLOSED) 2416 chan_mark_dead(c); 2417 } 2418} 2419 2420static void 2421session_close_single_x11(int id, void *arg) 2422{ 2423 Session *s; 2424 u_int i; 2425 2426 debug3("session_close_single_x11: channel %d", id); 2427 channel_cancel_cleanup(id); 2428 if ((s = session_by_x11_channel(id)) == NULL) 2429 fatal("session_close_single_x11: no x11 channel %d", id); 2430 for (i = 0; s->x11_chanids[i] != -1; i++) { 2431 debug("session_close_single_x11: session %d: " 2432 "closing channel %d", s->self, s->x11_chanids[i]); 2433 /* 2434 * The channel "id" is already closing, but make sure we 2435 * close all of its siblings. 2436 */ 2437 if (s->x11_chanids[i] != id) 2438 session_close_x11(s->x11_chanids[i]); 2439 } 2440 xfree(s->x11_chanids); 2441 s->x11_chanids = NULL; 2442 if (s->display) { 2443 xfree(s->display); 2444 s->display = NULL; 2445 } 2446 if (s->auth_proto) { 2447 xfree(s->auth_proto); 2448 s->auth_proto = NULL; 2449 } 2450 if (s->auth_data) { 2451 xfree(s->auth_data); 2452 s->auth_data = NULL; 2453 } 2454 if (s->auth_display) { 2455 xfree(s->auth_display); 2456 s->auth_display = NULL; 2457 } 2458} 2459 2460static void 2461session_exit_message(Session *s, int status) 2462{ 2463 Channel *c; 2464 2465 if ((c = channel_lookup(s->chanid)) == NULL) 2466 fatal("session_exit_message: session %d: no channel %d", 2467 s->self, s->chanid); 2468 debug("session_exit_message: session %d channel %d pid %ld", 2469 s->self, s->chanid, (long)s->pid); 2470 2471 if (WIFEXITED(status)) { 2472 channel_request_start(s->chanid, "exit-status", 0); 2473 packet_put_int(WEXITSTATUS(status)); 2474 packet_send(); 2475 } else if (WIFSIGNALED(status)) { 2476 channel_request_start(s->chanid, "exit-signal", 0); 2477 packet_put_cstring(sig2name(WTERMSIG(status))); 2478#ifdef WCOREDUMP 2479 packet_put_char(WCOREDUMP(status)? 1 : 0); 2480#else /* WCOREDUMP */ 2481 packet_put_char(0); 2482#endif /* WCOREDUMP */ 2483 packet_put_cstring(""); 2484 packet_put_cstring(""); 2485 packet_send(); 2486 } else { 2487 /* Some weird exit cause. Just exit. */ 2488 packet_disconnect("wait returned status %04x.", status); 2489 } 2490 2491 /* disconnect channel */ 2492 debug("session_exit_message: release channel %d", s->chanid); 2493 2494 /* 2495 * Adjust cleanup callback attachment to send close messages when 2496 * the channel gets EOF. The session will be then be closed 2497 * by session_close_by_channel when the childs close their fds. 2498 */ 2499 channel_register_cleanup(c->self, session_close_by_channel, 1); 2500 2501 /* 2502 * emulate a write failure with 'chan_write_failed', nobody will be 2503 * interested in data we write. 2504 * Note that we must not call 'chan_read_failed', since there could 2505 * be some more data waiting in the pipe. 2506 */ 2507 if (c->ostate != CHAN_OUTPUT_CLOSED) 2508 chan_write_failed(c); 2509} 2510 2511void 2512session_close(Session *s) 2513{ 2514 u_int i; 2515 2516 debug("session_close: session %d pid %ld", s->self, (long)s->pid); 2517 if (s->ttyfd != -1) 2518 session_pty_cleanup(s); 2519 if (s->term) 2520 xfree(s->term); 2521 if (s->display) 2522 xfree(s->display); 2523 if (s->x11_chanids) 2524 xfree(s->x11_chanids); 2525 if (s->auth_display) 2526 xfree(s->auth_display); 2527 if (s->auth_data) 2528 xfree(s->auth_data); 2529 if (s->auth_proto) 2530 xfree(s->auth_proto); 2531 if (s->env != NULL) { 2532 for (i = 0; i < s->num_env; i++) { 2533 xfree(s->env[i].name); 2534 xfree(s->env[i].val); 2535 } 2536 xfree(s->env); 2537 } 2538 session_proctitle(s); 2539 session_unused(s->self); 2540} 2541 2542void 2543session_close_by_pid(pid_t pid, int status) 2544{ 2545 Session *s = session_by_pid(pid); 2546 if (s == NULL) { 2547 debug("session_close_by_pid: no session for pid %ld", 2548 (long)pid); 2549 return; 2550 } 2551 if (s->chanid != -1) 2552 session_exit_message(s, status); 2553 if (s->ttyfd != -1) 2554 session_pty_cleanup(s); 2555 s->pid = 0; 2556} 2557 2558/* 2559 * this is called when a channel dies before 2560 * the session 'child' itself dies 2561 */ 2562void 2563session_close_by_channel(int id, void *arg) 2564{ 2565 Session *s = session_by_channel(id); 2566 u_int i; 2567 2568 if (s == NULL) { 2569 debug("session_close_by_channel: no session for id %d", id); 2570 return; 2571 } 2572 debug("session_close_by_channel: channel %d child %ld", 2573 id, (long)s->pid); 2574 if (s->pid != 0) { 2575 debug("session_close_by_channel: channel %d: has child", id); 2576 /* 2577 * delay detach of session, but release pty, since 2578 * the fd's to the child are already closed 2579 */ 2580 if (s->ttyfd != -1) 2581 session_pty_cleanup(s); 2582 return; 2583 } 2584 /* detach by removing callback */ 2585 channel_cancel_cleanup(s->chanid); 2586 2587 /* Close any X11 listeners associated with this session */ 2588 if (s->x11_chanids != NULL) { 2589 for (i = 0; s->x11_chanids[i] != -1; i++) { 2590 session_close_x11(s->x11_chanids[i]); 2591 s->x11_chanids[i] = -1; 2592 } 2593 } 2594 2595 s->chanid = -1; 2596 session_close(s); 2597} 2598 2599void 2600session_destroy_all(void (*closefunc)(Session *)) 2601{ 2602 int i; 2603 for (i = 0; i < sessions_nalloc; i++) { 2604 Session *s = &sessions[i]; 2605 if (s->used) { 2606 if (closefunc != NULL) 2607 closefunc(s); 2608 else 2609 session_close(s); 2610 } 2611 } 2612} 2613 2614static char * 2615session_tty_list(void) 2616{ 2617 static char buf[1024]; 2618 int i; 2619 char *cp; 2620 2621 buf[0] = '\0'; 2622 for (i = 0; i < sessions_nalloc; i++) { 2623 Session *s = &sessions[i]; 2624 if (s->used && s->ttyfd != -1) { 2625 2626 if (strncmp(s->tty, "/dev/", 5) != 0) { 2627 cp = strrchr(s->tty, '/'); 2628 cp = (cp == NULL) ? s->tty : cp + 1; 2629 } else 2630 cp = s->tty + 5; 2631 2632 if (buf[0] != '\0') 2633 strlcat(buf, ",", sizeof buf); 2634 strlcat(buf, cp, sizeof buf); 2635 } 2636 } 2637 if (buf[0] == '\0') 2638 strlcpy(buf, "notty", sizeof buf); 2639 return buf; 2640} 2641 2642void 2643session_proctitle(Session *s) 2644{ 2645 if (s->pw == NULL) 2646 error("no user for session %d", s->self); 2647 else 2648 setproctitle("%s@%s", s->pw->pw_name, session_tty_list()); 2649} 2650 2651int 2652session_setup_x11fwd(Session *s) 2653{ 2654 struct stat st; 2655 char display[512], auth_display[512]; 2656 char hostname[MAXHOSTNAMELEN]; 2657 u_int i; 2658 2659 if (no_x11_forwarding_flag) { 2660 packet_send_debug("X11 forwarding disabled in user configuration file."); 2661 return 0; 2662 } 2663 if (!options.x11_forwarding) { 2664 debug("X11 forwarding disabled in server configuration file."); 2665 return 0; 2666 } 2667 if (!options.xauth_location || 2668 (stat(options.xauth_location, &st) == -1)) { 2669 packet_send_debug("No xauth program; cannot forward with spoofing."); 2670 return 0; 2671 } 2672 if (options.use_login) { 2673 packet_send_debug("X11 forwarding disabled; " 2674 "not compatible with UseLogin=yes."); 2675 return 0; 2676 } 2677 if (s->display != NULL) { 2678 debug("X11 display already set."); 2679 return 0; 2680 } 2681 if (x11_create_display_inet(options.x11_display_offset, 2682 options.x11_use_localhost, s->single_connection, 2683 &s->display_number, &s->x11_chanids) == -1) { 2684 debug("x11_create_display_inet failed."); 2685 return 0; 2686 } 2687 for (i = 0; s->x11_chanids[i] != -1; i++) { 2688 channel_register_cleanup(s->x11_chanids[i], 2689 session_close_single_x11, 0); 2690 } 2691 2692 /* Set up a suitable value for the DISPLAY variable. */ 2693 if (gethostname(hostname, sizeof(hostname)) < 0) 2694 fatal("gethostname: %.100s", strerror(errno)); 2695 /* 2696 * auth_display must be used as the displayname when the 2697 * authorization entry is added with xauth(1). This will be 2698 * different than the DISPLAY string for localhost displays. 2699 */ 2700 if (options.x11_use_localhost) { 2701 snprintf(display, sizeof display, "localhost:%u.%u", 2702 s->display_number, s->screen); 2703 snprintf(auth_display, sizeof auth_display, "unix:%u.%u", 2704 s->display_number, s->screen); 2705 s->display = xstrdup(display); 2706 s->auth_display = xstrdup(auth_display); 2707 } else { 2708#ifdef IPADDR_IN_DISPLAY 2709 struct hostent *he; 2710 struct in_addr my_addr; 2711 2712 he = gethostbyname(hostname); 2713 if (he == NULL) { 2714 error("Can't get IP address for X11 DISPLAY."); 2715 packet_send_debug("Can't get IP address for X11 DISPLAY."); 2716 return 0; 2717 } 2718 memcpy(&my_addr, he->h_addr_list[0], sizeof(struct in_addr)); 2719 snprintf(display, sizeof display, "%.50s:%u.%u", inet_ntoa(my_addr), 2720 s->display_number, s->screen); 2721#else 2722 snprintf(display, sizeof display, "%.400s:%u.%u", hostname, 2723 s->display_number, s->screen); 2724#endif 2725 s->display = xstrdup(display); 2726 s->auth_display = xstrdup(display); 2727 } 2728 2729 return 1; 2730} 2731 2732static void 2733do_authenticated2(Authctxt *authctxt) 2734{ 2735 server_loop2(authctxt); 2736} 2737 2738void 2739do_cleanup(Authctxt *authctxt) 2740{ 2741 static int called = 0; 2742 2743 debug("do_cleanup"); 2744 2745 /* no cleanup if we're in the child for login shell */ 2746 if (is_child) 2747 return; 2748 2749 /* avoid double cleanup */ 2750 if (called) 2751 return; 2752 called = 1; 2753 2754 if (authctxt == NULL) 2755 return; 2756 2757#ifdef USE_PAM 2758 if (options.use_pam) { 2759 sshpam_cleanup(); 2760 sshpam_thread_cleanup(); 2761 } 2762#endif 2763 2764 if (!authctxt->authenticated) 2765 return; 2766 2767#ifdef KRB5 2768 if (options.kerberos_ticket_cleanup && 2769 authctxt->krb5_ctx) 2770 krb5_cleanup_proc(authctxt); 2771#endif 2772 2773#ifdef GSSAPI 2774 if (compat20 && options.gss_cleanup_creds) 2775 ssh_gssapi_cleanup_creds(); 2776#endif 2777 2778 /* remove agent socket */ 2779 auth_sock_cleanup_proc(authctxt->pw); 2780 2781 /* 2782 * Cleanup ptys/utmp only if privsep is disabled, 2783 * or if running in monitor. 2784 */ 2785 if (!use_privsep || mm_is_monitor()) 2786 session_destroy_all(session_pty_cleanup2); 2787} 2788