session.c revision 213250
1/* $OpenBSD: session.c,v 1.252 2010/03/07 11:57:13 dtucker 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 213250 2010-09-28 20:57:14Z emaste $"); 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#define SUBSYSTEM_INT_SFTP_ERROR 3 150 151#ifdef HAVE_LOGIN_CAP 152login_cap_t *lc; 153#endif 154 155static int is_child = 0; 156 157/* Name and directory of socket for authentication agent forwarding. */ 158static char *auth_sock_name = NULL; 159static char *auth_sock_dir = NULL; 160 161/* removes the agent forwarding socket */ 162 163static void 164auth_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 175static int 176auth_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 nc = channel_new("auth socket", 236 SSH_CHANNEL_AUTH_SOCKET, sock, sock, -1, 237 CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 238 0, "auth socket", 1); 239 nc->path = xstrdup(auth_sock_name); 240 return 1; 241 242 authsock_err: 243 if (auth_sock_name != NULL) 244 xfree(auth_sock_name); 245 if (auth_sock_dir != NULL) { 246 rmdir(auth_sock_dir); 247 xfree(auth_sock_dir); 248 } 249 if (sock != -1) 250 close(sock); 251 auth_sock_name = NULL; 252 auth_sock_dir = NULL; 253 return 0; 254} 255 256static void 257display_loginmsg(void) 258{ 259 if (buffer_len(&loginmsg) > 0) { 260 buffer_append(&loginmsg, "\0", 1); 261 printf("%s", (char *)buffer_ptr(&loginmsg)); 262 buffer_clear(&loginmsg); 263 } 264} 265 266void 267do_authenticated(Authctxt *authctxt) 268{ 269 setproctitle("%s", authctxt->pw->pw_name); 270 271 /* setup the channel layer */ 272 if (!no_port_forwarding_flag && options.allow_tcp_forwarding) 273 channel_permit_all_opens(); 274 275 auth_debug_send(); 276 277 if (compat20) 278 do_authenticated2(authctxt); 279 else 280 do_authenticated1(authctxt); 281 282 do_cleanup(authctxt); 283} 284 285/* 286 * Prepares for an interactive session. This is called after the user has 287 * been successfully authenticated. During this message exchange, pseudo 288 * terminals are allocated, X11, TCP/IP, and authentication agent forwardings 289 * are requested, etc. 290 */ 291static void 292do_authenticated1(Authctxt *authctxt) 293{ 294 Session *s; 295 char *command; 296 int success, type, screen_flag; 297 int enable_compression_after_reply = 0; 298 u_int proto_len, data_len, dlen, compression_level = 0; 299 300 s = session_new(); 301 if (s == NULL) { 302 error("no more sessions"); 303 return; 304 } 305 s->authctxt = authctxt; 306 s->pw = authctxt->pw; 307 308 /* 309 * We stay in this loop until the client requests to execute a shell 310 * or a command. 311 */ 312 for (;;) { 313 success = 0; 314 315 /* Get a packet from the client. */ 316 type = packet_read(); 317 318 /* Process the packet. */ 319 switch (type) { 320 case SSH_CMSG_REQUEST_COMPRESSION: 321 compression_level = packet_get_int(); 322 packet_check_eom(); 323 if (compression_level < 1 || compression_level > 9) { 324 packet_send_debug("Received invalid compression level %d.", 325 compression_level); 326 break; 327 } 328 if (options.compression == COMP_NONE) { 329 debug2("compression disabled"); 330 break; 331 } 332 /* Enable compression after we have responded with SUCCESS. */ 333 enable_compression_after_reply = 1; 334 success = 1; 335 break; 336 337 case SSH_CMSG_REQUEST_PTY: 338 success = session_pty_req(s); 339 break; 340 341 case SSH_CMSG_X11_REQUEST_FORWARDING: 342 s->auth_proto = packet_get_string(&proto_len); 343 s->auth_data = packet_get_string(&data_len); 344 345 screen_flag = packet_get_protocol_flags() & 346 SSH_PROTOFLAG_SCREEN_NUMBER; 347 debug2("SSH_PROTOFLAG_SCREEN_NUMBER: %d", screen_flag); 348 349 if (packet_remaining() == 4) { 350 if (!screen_flag) 351 debug2("Buggy client: " 352 "X11 screen flag missing"); 353 s->screen = packet_get_int(); 354 } else { 355 s->screen = 0; 356 } 357 packet_check_eom(); 358 success = session_setup_x11fwd(s); 359 if (!success) { 360 xfree(s->auth_proto); 361 xfree(s->auth_data); 362 s->auth_proto = NULL; 363 s->auth_data = NULL; 364 } 365 break; 366 367 case SSH_CMSG_AGENT_REQUEST_FORWARDING: 368 if (!options.allow_agent_forwarding || 369 no_agent_forwarding_flag || compat13) { 370 debug("Authentication agent forwarding not permitted for this authentication."); 371 break; 372 } 373 debug("Received authentication agent forwarding request."); 374 success = auth_input_request_forwarding(s->pw); 375 break; 376 377 case SSH_CMSG_PORT_FORWARD_REQUEST: 378 if (no_port_forwarding_flag) { 379 debug("Port forwarding not permitted for this authentication."); 380 break; 381 } 382 if (!options.allow_tcp_forwarding) { 383 debug("Port forwarding not permitted."); 384 break; 385 } 386 debug("Received TCP/IP port forwarding request."); 387 if (channel_input_port_forward_request(s->pw->pw_uid == 0, 388 options.gateway_ports) < 0) { 389 debug("Port forwarding failed."); 390 break; 391 } 392 success = 1; 393 break; 394 395 case SSH_CMSG_MAX_PACKET_SIZE: 396 if (packet_set_maxsize(packet_get_int()) > 0) 397 success = 1; 398 break; 399 400 case SSH_CMSG_EXEC_SHELL: 401 case SSH_CMSG_EXEC_CMD: 402 if (type == SSH_CMSG_EXEC_CMD) { 403 command = packet_get_string(&dlen); 404 debug("Exec command '%.500s'", command); 405 if (do_exec(s, command) != 0) 406 packet_disconnect( 407 "command execution failed"); 408 xfree(command); 409 } else { 410 if (do_exec(s, NULL) != 0) 411 packet_disconnect( 412 "shell execution failed"); 413 } 414 packet_check_eom(); 415 session_close(s); 416 return; 417 418 default: 419 /* 420 * Any unknown messages in this phase are ignored, 421 * and a failure message is returned. 422 */ 423 logit("Unknown packet type received after authentication: %d", type); 424 } 425 packet_start(success ? SSH_SMSG_SUCCESS : SSH_SMSG_FAILURE); 426 packet_send(); 427 packet_write_wait(); 428 429 /* Enable compression now that we have replied if appropriate. */ 430 if (enable_compression_after_reply) { 431 enable_compression_after_reply = 0; 432 packet_start_compression(compression_level); 433 } 434 } 435} 436 437#define USE_PIPES 438/* 439 * This is called to fork and execute a command when we have no tty. This 440 * will call do_child from the child, and server_loop from the parent after 441 * setting up file descriptors and such. 442 */ 443int 444do_exec_no_pty(Session *s, const char *command) 445{ 446 pid_t pid; 447 448#ifdef USE_PIPES 449 int pin[2], pout[2], perr[2]; 450 451 /* Allocate pipes for communicating with the program. */ 452 if (pipe(pin) < 0) { 453 error("%s: pipe in: %.100s", __func__, strerror(errno)); 454 return -1; 455 } 456 if (pipe(pout) < 0) { 457 error("%s: pipe out: %.100s", __func__, strerror(errno)); 458 close(pin[0]); 459 close(pin[1]); 460 return -1; 461 } 462 if (pipe(perr) < 0) { 463 error("%s: pipe err: %.100s", __func__, strerror(errno)); 464 close(pin[0]); 465 close(pin[1]); 466 close(pout[0]); 467 close(pout[1]); 468 return -1; 469 } 470#else 471 int inout[2], err[2]; 472 473 /* Uses socket pairs to communicate with the program. */ 474 if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) < 0) { 475 error("%s: socketpair #1: %.100s", __func__, strerror(errno)); 476 return -1; 477 } 478 if (socketpair(AF_UNIX, SOCK_STREAM, 0, err) < 0) { 479 error("%s: socketpair #2: %.100s", __func__, strerror(errno)); 480 close(inout[0]); 481 close(inout[1]); 482 return -1; 483 } 484#endif 485 486 if (s == NULL) 487 fatal("do_exec_no_pty: no session"); 488 489 session_proctitle(s); 490 491 /* Fork the child. */ 492 switch ((pid = fork())) { 493 case -1: 494 error("%s: fork: %.100s", __func__, strerror(errno)); 495#ifdef USE_PIPES 496 close(pin[0]); 497 close(pin[1]); 498 close(pout[0]); 499 close(pout[1]); 500 close(perr[0]); 501 close(perr[1]); 502#else 503 close(inout[0]); 504 close(inout[1]); 505 close(err[0]); 506 close(err[1]); 507#endif 508 return -1; 509 case 0: 510 is_child = 1; 511 512 /* Child. Reinitialize the log since the pid has changed. */ 513 log_init(__progname, options.log_level, 514 options.log_facility, log_stderr); 515 516 /* 517 * Create a new session and process group since the 4.4BSD 518 * setlogin() affects the entire process group. 519 */ 520 if (setsid() < 0) 521 error("setsid failed: %.100s", strerror(errno)); 522 523#ifdef USE_PIPES 524 /* 525 * Redirect stdin. We close the parent side of the socket 526 * pair, and make the child side the standard input. 527 */ 528 close(pin[1]); 529 if (dup2(pin[0], 0) < 0) 530 perror("dup2 stdin"); 531 close(pin[0]); 532 533 /* Redirect stdout. */ 534 close(pout[0]); 535 if (dup2(pout[1], 1) < 0) 536 perror("dup2 stdout"); 537 close(pout[1]); 538 539 /* Redirect stderr. */ 540 close(perr[0]); 541 if (dup2(perr[1], 2) < 0) 542 perror("dup2 stderr"); 543 close(perr[1]); 544#else 545 /* 546 * Redirect stdin, stdout, and stderr. Stdin and stdout will 547 * use the same socket, as some programs (particularly rdist) 548 * seem to depend on it. 549 */ 550 close(inout[1]); 551 close(err[1]); 552 if (dup2(inout[0], 0) < 0) /* stdin */ 553 perror("dup2 stdin"); 554 if (dup2(inout[0], 1) < 0) /* stdout (same as stdin) */ 555 perror("dup2 stdout"); 556 close(inout[0]); 557 if (dup2(err[0], 2) < 0) /* stderr */ 558 perror("dup2 stderr"); 559 close(err[0]); 560#endif 561 562 563#ifdef _UNICOS 564 cray_init_job(s->pw); /* set up cray jid and tmpdir */ 565#endif 566 567 /* Do processing for the child (exec command etc). */ 568 do_child(s, command); 569 /* NOTREACHED */ 570 default: 571 break; 572 } 573 574#ifdef _UNICOS 575 signal(WJSIGNAL, cray_job_termination_handler); 576#endif /* _UNICOS */ 577#ifdef HAVE_CYGWIN 578 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); 579#endif 580 581 s->pid = pid; 582 /* Set interactive/non-interactive mode. */ 583 packet_set_interactive(s->display != NULL); 584 585 /* 586 * Clear loginmsg, since it's the child's responsibility to display 587 * it to the user, otherwise multiple sessions may accumulate 588 * multiple copies of the login messages. 589 */ 590 buffer_clear(&loginmsg); 591 592#ifdef USE_PIPES 593 /* We are the parent. Close the child sides of the pipes. */ 594 close(pin[0]); 595 close(pout[1]); 596 close(perr[1]); 597 598 if (compat20) { 599 if (s->is_subsystem) { 600 close(perr[0]); 601 perr[0] = -1; 602 } 603 session_set_fds(s, pin[1], pout[0], perr[0], 0); 604 } else { 605 /* Enter the interactive session. */ 606 server_loop(pid, pin[1], pout[0], perr[0]); 607 /* server_loop has closed pin[1], pout[0], and perr[0]. */ 608 } 609#else 610 /* We are the parent. Close the child sides of the socket pairs. */ 611 close(inout[0]); 612 close(err[0]); 613 614 /* 615 * Enter the interactive session. Note: server_loop must be able to 616 * handle the case that fdin and fdout are the same. 617 */ 618 if (compat20) { 619 session_set_fds(s, inout[1], inout[1], 620 s->is_subsystem ? -1 : err[1], 0); 621 if (s->is_subsystem) 622 close(err[1]); 623 } else { 624 server_loop(pid, inout[1], inout[1], err[1]); 625 /* server_loop has closed inout[1] and err[1]. */ 626 } 627#endif 628 return 0; 629} 630 631/* 632 * This is called to fork and execute a command when we have a tty. This 633 * will call do_child from the child, and server_loop from the parent after 634 * setting up file descriptors, controlling tty, updating wtmp, utmp, 635 * lastlog, and other such operations. 636 */ 637int 638do_exec_pty(Session *s, const char *command) 639{ 640 int fdout, ptyfd, ttyfd, ptymaster; 641 pid_t pid; 642 643 if (s == NULL) 644 fatal("do_exec_pty: no session"); 645 ptyfd = s->ptyfd; 646 ttyfd = s->ttyfd; 647 648 /* 649 * Create another descriptor of the pty master side for use as the 650 * standard input. We could use the original descriptor, but this 651 * simplifies code in server_loop. The descriptor is bidirectional. 652 * Do this before forking (and cleanup in the child) so as to 653 * detect and gracefully fail out-of-fd conditions. 654 */ 655 if ((fdout = dup(ptyfd)) < 0) { 656 error("%s: dup #1: %s", __func__, strerror(errno)); 657 close(ttyfd); 658 close(ptyfd); 659 return -1; 660 } 661 /* we keep a reference to the pty master */ 662 if ((ptymaster = dup(ptyfd)) < 0) { 663 error("%s: dup #2: %s", __func__, strerror(errno)); 664 close(ttyfd); 665 close(ptyfd); 666 close(fdout); 667 return -1; 668 } 669 670 /* Fork the child. */ 671 switch ((pid = fork())) { 672 case -1: 673 error("%s: fork: %.100s", __func__, strerror(errno)); 674 close(fdout); 675 close(ptymaster); 676 close(ttyfd); 677 close(ptyfd); 678 return -1; 679 case 0: 680 is_child = 1; 681 682 close(fdout); 683 close(ptymaster); 684 685 /* Child. Reinitialize the log because the pid has changed. */ 686 log_init(__progname, options.log_level, 687 options.log_facility, log_stderr); 688 /* Close the master side of the pseudo tty. */ 689 close(ptyfd); 690 691 /* Make the pseudo tty our controlling tty. */ 692 pty_make_controlling_tty(&ttyfd, s->tty); 693 694 /* Redirect stdin/stdout/stderr from the pseudo tty. */ 695 if (dup2(ttyfd, 0) < 0) 696 error("dup2 stdin: %s", strerror(errno)); 697 if (dup2(ttyfd, 1) < 0) 698 error("dup2 stdout: %s", strerror(errno)); 699 if (dup2(ttyfd, 2) < 0) 700 error("dup2 stderr: %s", strerror(errno)); 701 702 /* Close the extra descriptor for the pseudo tty. */ 703 close(ttyfd); 704 705 /* record login, etc. similar to login(1) */ 706#ifndef HAVE_OSF_SIA 707 if (!(options.use_login && command == NULL)) { 708#ifdef _UNICOS 709 cray_init_job(s->pw); /* set up cray jid and tmpdir */ 710#endif /* _UNICOS */ 711 do_login(s, command); 712 } 713# ifdef LOGIN_NEEDS_UTMPX 714 else 715 do_pre_login(s); 716# endif 717#endif 718 /* 719 * Do common processing for the child, such as execing 720 * the command. 721 */ 722 do_child(s, command); 723 /* NOTREACHED */ 724 default: 725 break; 726 } 727 728#ifdef _UNICOS 729 signal(WJSIGNAL, cray_job_termination_handler); 730#endif /* _UNICOS */ 731#ifdef HAVE_CYGWIN 732 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); 733#endif 734 735 s->pid = pid; 736 737 /* Parent. Close the slave side of the pseudo tty. */ 738 close(ttyfd); 739 740 /* Enter interactive session. */ 741 s->ptymaster = ptymaster; 742 packet_set_interactive(1); 743 if (compat20) { 744 session_set_fds(s, ptyfd, fdout, -1, 1); 745 } else { 746 server_loop(pid, ptyfd, fdout, -1); 747 /* server_loop _has_ closed ptyfd and fdout. */ 748 } 749 return 0; 750} 751 752#ifdef LOGIN_NEEDS_UTMPX 753static void 754do_pre_login(Session *s) 755{ 756 socklen_t fromlen; 757 struct sockaddr_storage from; 758 pid_t pid = getpid(); 759 760 /* 761 * Get IP address of client. If the connection is not a socket, let 762 * the address be 0.0.0.0. 763 */ 764 memset(&from, 0, sizeof(from)); 765 fromlen = sizeof(from); 766 if (packet_connection_is_on_socket()) { 767 if (getpeername(packet_get_connection_in(), 768 (struct sockaddr *)&from, &fromlen) < 0) { 769 debug("getpeername: %.100s", strerror(errno)); 770 cleanup_exit(255); 771 } 772 } 773 774 record_utmp_only(pid, s->tty, s->pw->pw_name, 775 get_remote_name_or_ip(utmp_len, options.use_dns), 776 (struct sockaddr *)&from, fromlen); 777} 778#endif 779 780/* 781 * This is called to fork and execute a command. If another command is 782 * to be forced, execute that instead. 783 */ 784int 785do_exec(Session *s, const char *command) 786{ 787 int ret; 788 789 if (options.adm_forced_command) { 790 original_command = command; 791 command = options.adm_forced_command; 792 if (IS_INTERNAL_SFTP(command)) { 793 s->is_subsystem = s->is_subsystem ? 794 SUBSYSTEM_INT_SFTP : SUBSYSTEM_INT_SFTP_ERROR; 795 } else if (s->is_subsystem) 796 s->is_subsystem = SUBSYSTEM_EXT; 797 debug("Forced command (config) '%.900s'", command); 798 } else if (forced_command) { 799 original_command = command; 800 command = forced_command; 801 if (IS_INTERNAL_SFTP(command)) { 802 s->is_subsystem = s->is_subsystem ? 803 SUBSYSTEM_INT_SFTP : SUBSYSTEM_INT_SFTP_ERROR; 804 } else if (s->is_subsystem) 805 s->is_subsystem = SUBSYSTEM_EXT; 806 debug("Forced command (key option) '%.900s'", command); 807 } 808 809#ifdef SSH_AUDIT_EVENTS 810 if (command != NULL) 811 PRIVSEP(audit_run_command(command)); 812 else if (s->ttyfd == -1) { 813 char *shell = s->pw->pw_shell; 814 815 if (shell[0] == '\0') /* empty shell means /bin/sh */ 816 shell =_PATH_BSHELL; 817 PRIVSEP(audit_run_command(shell)); 818 } 819#endif 820 if (s->ttyfd != -1) 821 ret = do_exec_pty(s, command); 822 else 823 ret = do_exec_no_pty(s, command); 824 825 original_command = NULL; 826 827 /* 828 * Clear loginmsg: it's the child's responsibility to display 829 * it to the user, otherwise multiple sessions may accumulate 830 * multiple copies of the login messages. 831 */ 832 buffer_clear(&loginmsg); 833 834 return ret; 835} 836 837/* administrative, login(1)-like work */ 838void 839do_login(Session *s, const char *command) 840{ 841 socklen_t fromlen; 842 struct sockaddr_storage from; 843 struct passwd * pw = s->pw; 844 pid_t pid = getpid(); 845 846 /* 847 * Get IP address of client. If the connection is not a socket, let 848 * the address be 0.0.0.0. 849 */ 850 memset(&from, 0, sizeof(from)); 851 fromlen = sizeof(from); 852 if (packet_connection_is_on_socket()) { 853 if (getpeername(packet_get_connection_in(), 854 (struct sockaddr *)&from, &fromlen) < 0) { 855 debug("getpeername: %.100s", strerror(errno)); 856 cleanup_exit(255); 857 } 858 } 859 860 /* Record that there was a login on that tty from the remote host. */ 861 if (!use_privsep) 862 record_login(pid, s->tty, pw->pw_name, pw->pw_uid, 863 get_remote_name_or_ip(utmp_len, 864 options.use_dns), 865 (struct sockaddr *)&from, fromlen); 866 867#ifdef USE_PAM 868 /* 869 * If password change is needed, do it now. 870 * This needs to occur before the ~/.hushlogin check. 871 */ 872 if (options.use_pam && !use_privsep && s->authctxt->force_pwchange) { 873 display_loginmsg(); 874 do_pam_chauthtok(); 875 s->authctxt->force_pwchange = 0; 876 /* XXX - signal [net] parent to enable forwardings */ 877 } 878#endif 879 880 if (check_quietlogin(s, command)) 881 return; 882 883 display_loginmsg(); 884 885 do_motd(); 886} 887 888/* 889 * Display the message of the day. 890 */ 891void 892do_motd(void) 893{ 894 FILE *f; 895 char buf[256]; 896 897 if (options.print_motd) { 898#ifdef HAVE_LOGIN_CAP 899 f = fopen(login_getcapstr(lc, "welcome", "/etc/motd", 900 "/etc/motd"), "r"); 901#else 902 f = fopen("/etc/motd", "r"); 903#endif 904 if (f) { 905 while (fgets(buf, sizeof(buf), f)) 906 fputs(buf, stdout); 907 fclose(f); 908 } 909 } 910} 911 912 913/* 914 * Check for quiet login, either .hushlogin or command given. 915 */ 916int 917check_quietlogin(Session *s, const char *command) 918{ 919 char buf[256]; 920 struct passwd *pw = s->pw; 921 struct stat st; 922 923 /* Return 1 if .hushlogin exists or a command given. */ 924 if (command != NULL) 925 return 1; 926 snprintf(buf, sizeof(buf), "%.200s/.hushlogin", pw->pw_dir); 927#ifdef HAVE_LOGIN_CAP 928 if (login_getcapbool(lc, "hushlogin", 0) || stat(buf, &st) >= 0) 929 return 1; 930#else 931 if (stat(buf, &st) >= 0) 932 return 1; 933#endif 934 return 0; 935} 936 937/* 938 * Sets the value of the given variable in the environment. If the variable 939 * already exists, its value is overridden. 940 */ 941void 942child_set_env(char ***envp, u_int *envsizep, const char *name, 943 const char *value) 944{ 945 char **env; 946 u_int envsize; 947 u_int i, namelen; 948 949 /* 950 * If we're passed an uninitialized list, allocate a single null 951 * entry before continuing. 952 */ 953 if (*envp == NULL && *envsizep == 0) { 954 *envp = xmalloc(sizeof(char *)); 955 *envp[0] = NULL; 956 *envsizep = 1; 957 } 958 959 /* 960 * Find the slot where the value should be stored. If the variable 961 * already exists, we reuse the slot; otherwise we append a new slot 962 * at the end of the array, expanding if necessary. 963 */ 964 env = *envp; 965 namelen = strlen(name); 966 for (i = 0; env[i]; i++) 967 if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=') 968 break; 969 if (env[i]) { 970 /* Reuse the slot. */ 971 xfree(env[i]); 972 } else { 973 /* New variable. Expand if necessary. */ 974 envsize = *envsizep; 975 if (i >= envsize - 1) { 976 if (envsize >= 1000) 977 fatal("child_set_env: too many env vars"); 978 envsize += 50; 979 env = (*envp) = xrealloc(env, envsize, sizeof(char *)); 980 *envsizep = envsize; 981 } 982 /* Need to set the NULL pointer at end of array beyond the new slot. */ 983 env[i + 1] = NULL; 984 } 985 986 /* Allocate space and format the variable in the appropriate slot. */ 987 env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1); 988 snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value); 989} 990 991/* 992 * Reads environment variables from the given file and adds/overrides them 993 * into the environment. If the file does not exist, this does nothing. 994 * Otherwise, it must consist of empty lines, comments (line starts with '#') 995 * and assignments of the form name=value. No other forms are allowed. 996 */ 997static void 998read_environment_file(char ***env, u_int *envsize, 999 const char *filename) 1000{ 1001 FILE *f; 1002 char buf[4096]; 1003 char *cp, *value; 1004 u_int lineno = 0; 1005 1006 f = fopen(filename, "r"); 1007 if (!f) 1008 return; 1009 1010 while (fgets(buf, sizeof(buf), f)) { 1011 if (++lineno > 1000) 1012 fatal("Too many lines in environment file %s", filename); 1013 for (cp = buf; *cp == ' ' || *cp == '\t'; cp++) 1014 ; 1015 if (!*cp || *cp == '#' || *cp == '\n') 1016 continue; 1017 1018 cp[strcspn(cp, "\n")] = '\0'; 1019 1020 value = strchr(cp, '='); 1021 if (value == NULL) { 1022 fprintf(stderr, "Bad line %u in %.100s\n", lineno, 1023 filename); 1024 continue; 1025 } 1026 /* 1027 * Replace the equals sign by nul, and advance value to 1028 * the value string. 1029 */ 1030 *value = '\0'; 1031 value++; 1032 child_set_env(env, envsize, cp, value); 1033 } 1034 fclose(f); 1035} 1036 1037#ifdef HAVE_ETC_DEFAULT_LOGIN 1038/* 1039 * Return named variable from specified environment, or NULL if not present. 1040 */ 1041static char * 1042child_get_env(char **env, const char *name) 1043{ 1044 int i; 1045 size_t len; 1046 1047 len = strlen(name); 1048 for (i=0; env[i] != NULL; i++) 1049 if (strncmp(name, env[i], len) == 0 && env[i][len] == '=') 1050 return(env[i] + len + 1); 1051 return NULL; 1052} 1053 1054/* 1055 * Read /etc/default/login. 1056 * We pick up the PATH (or SUPATH for root) and UMASK. 1057 */ 1058static void 1059read_etc_default_login(char ***env, u_int *envsize, uid_t uid) 1060{ 1061 char **tmpenv = NULL, *var; 1062 u_int i, tmpenvsize = 0; 1063 u_long mask; 1064 1065 /* 1066 * We don't want to copy the whole file to the child's environment, 1067 * so we use a temporary environment and copy the variables we're 1068 * interested in. 1069 */ 1070 read_environment_file(&tmpenv, &tmpenvsize, "/etc/default/login"); 1071 1072 if (tmpenv == NULL) 1073 return; 1074 1075 if (uid == 0) 1076 var = child_get_env(tmpenv, "SUPATH"); 1077 else 1078 var = child_get_env(tmpenv, "PATH"); 1079 if (var != NULL) 1080 child_set_env(env, envsize, "PATH", var); 1081 1082 if ((var = child_get_env(tmpenv, "UMASK")) != NULL) 1083 if (sscanf(var, "%5lo", &mask) == 1) 1084 umask((mode_t)mask); 1085 1086 for (i = 0; tmpenv[i] != NULL; i++) 1087 xfree(tmpenv[i]); 1088 xfree(tmpenv); 1089} 1090#endif /* HAVE_ETC_DEFAULT_LOGIN */ 1091 1092void 1093copy_environment(char **source, char ***env, u_int *envsize) 1094{ 1095 char *var_name, *var_val; 1096 int i; 1097 1098 if (source == NULL) 1099 return; 1100 1101 for(i = 0; source[i] != NULL; i++) { 1102 var_name = xstrdup(source[i]); 1103 if ((var_val = strstr(var_name, "=")) == NULL) { 1104 xfree(var_name); 1105 continue; 1106 } 1107 *var_val++ = '\0'; 1108 1109 debug3("Copy environment: %s=%s", var_name, var_val); 1110 child_set_env(env, envsize, var_name, var_val); 1111 1112 xfree(var_name); 1113 } 1114} 1115 1116static char ** 1117do_setup_env(Session *s, const char *shell) 1118{ 1119 char buf[256]; 1120 u_int i, envsize; 1121 char **env, *laddr; 1122 struct passwd *pw = s->pw; 1123#if !defined (HAVE_LOGIN_CAP) && !defined (HAVE_CYGWIN) 1124 char *path = NULL; 1125#else 1126 extern char **environ; 1127 char **senv, **var; 1128#endif 1129 1130 /* Initialize the environment. */ 1131 envsize = 100; 1132 env = xcalloc(envsize, sizeof(char *)); 1133 env[0] = NULL; 1134 1135#ifdef HAVE_CYGWIN 1136 /* 1137 * The Windows environment contains some setting which are 1138 * important for a running system. They must not be dropped. 1139 */ 1140 { 1141 char **p; 1142 1143 p = fetch_windows_environment(); 1144 copy_environment(p, &env, &envsize); 1145 free_windows_environment(p); 1146 } 1147#endif 1148 1149 if (getenv("TZ")) 1150 child_set_env(&env, &envsize, "TZ", getenv("TZ")); 1151 1152#ifdef GSSAPI 1153 /* Allow any GSSAPI methods that we've used to alter 1154 * the childs environment as they see fit 1155 */ 1156 ssh_gssapi_do_child(&env, &envsize); 1157#endif 1158 1159 if (!options.use_login) { 1160 /* Set basic environment. */ 1161 for (i = 0; i < s->num_env; i++) 1162 child_set_env(&env, &envsize, s->env[i].name, 1163 s->env[i].val); 1164 1165 child_set_env(&env, &envsize, "USER", pw->pw_name); 1166 child_set_env(&env, &envsize, "LOGNAME", pw->pw_name); 1167#ifdef _AIX 1168 child_set_env(&env, &envsize, "LOGIN", pw->pw_name); 1169#endif 1170 child_set_env(&env, &envsize, "HOME", pw->pw_dir); 1171 snprintf(buf, sizeof buf, "%.200s/%.50s", 1172 _PATH_MAILDIR, pw->pw_name); 1173 child_set_env(&env, &envsize, "MAIL", buf); 1174#ifdef HAVE_LOGIN_CAP 1175 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); 1176 child_set_env(&env, &envsize, "TERM", "su"); 1177 senv = environ; 1178 environ = xmalloc(sizeof(char *)); 1179 *environ = NULL; 1180 (void) setusercontext(lc, pw, pw->pw_uid, 1181 LOGIN_SETENV|LOGIN_SETPATH); 1182 copy_environment(environ, &env, &envsize); 1183 for (var = environ; *var != NULL; ++var) 1184 xfree(*var); 1185 xfree(environ); 1186 environ = senv; 1187#else /* HAVE_LOGIN_CAP */ 1188# ifndef HAVE_CYGWIN 1189 /* 1190 * There's no standard path on Windows. The path contains 1191 * important components pointing to the system directories, 1192 * needed for loading shared libraries. So the path better 1193 * remains intact here. 1194 */ 1195# ifdef HAVE_ETC_DEFAULT_LOGIN 1196 read_etc_default_login(&env, &envsize, pw->pw_uid); 1197 path = child_get_env(env, "PATH"); 1198# endif /* HAVE_ETC_DEFAULT_LOGIN */ 1199 if (path == NULL || *path == '\0') { 1200 child_set_env(&env, &envsize, "PATH", 1201 s->pw->pw_uid == 0 ? 1202 SUPERUSER_PATH : _PATH_STDPATH); 1203 } 1204# endif /* HAVE_CYGWIN */ 1205#endif /* HAVE_LOGIN_CAP */ 1206 1207 /* Normal systems set SHELL by default. */ 1208 child_set_env(&env, &envsize, "SHELL", shell); 1209 } 1210 1211 /* Set custom environment options from RSA authentication. */ 1212 if (!options.use_login) { 1213 while (custom_environment) { 1214 struct envstring *ce = custom_environment; 1215 char *str = ce->s; 1216 1217 for (i = 0; str[i] != '=' && str[i]; i++) 1218 ; 1219 if (str[i] == '=') { 1220 str[i] = 0; 1221 child_set_env(&env, &envsize, str, str + i + 1); 1222 } 1223 custom_environment = ce->next; 1224 xfree(ce->s); 1225 xfree(ce); 1226 } 1227 } 1228 1229 /* SSH_CLIENT deprecated */ 1230 snprintf(buf, sizeof buf, "%.50s %d %d", 1231 get_remote_ipaddr(), get_remote_port(), get_local_port()); 1232 child_set_env(&env, &envsize, "SSH_CLIENT", buf); 1233 1234 laddr = get_local_ipaddr(packet_get_connection_in()); 1235 snprintf(buf, sizeof buf, "%.50s %d %.50s %d", 1236 get_remote_ipaddr(), get_remote_port(), laddr, get_local_port()); 1237 xfree(laddr); 1238 child_set_env(&env, &envsize, "SSH_CONNECTION", buf); 1239 1240 if (s->ttyfd != -1) 1241 child_set_env(&env, &envsize, "SSH_TTY", s->tty); 1242 if (s->term) 1243 child_set_env(&env, &envsize, "TERM", s->term); 1244 if (s->display) 1245 child_set_env(&env, &envsize, "DISPLAY", s->display); 1246 if (original_command) 1247 child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND", 1248 original_command); 1249 1250#ifdef _UNICOS 1251 if (cray_tmpdir[0] != '\0') 1252 child_set_env(&env, &envsize, "TMPDIR", cray_tmpdir); 1253#endif /* _UNICOS */ 1254 1255 /* 1256 * Since we clear KRB5CCNAME at startup, if it's set now then it 1257 * must have been set by a native authentication method (eg AIX or 1258 * SIA), so copy it to the child. 1259 */ 1260 { 1261 char *cp; 1262 1263 if ((cp = getenv("KRB5CCNAME")) != NULL) 1264 child_set_env(&env, &envsize, "KRB5CCNAME", cp); 1265 } 1266 1267#ifdef _AIX 1268 { 1269 char *cp; 1270 1271 if ((cp = getenv("AUTHSTATE")) != NULL) 1272 child_set_env(&env, &envsize, "AUTHSTATE", cp); 1273 read_environment_file(&env, &envsize, "/etc/environment"); 1274 } 1275#endif 1276#ifdef KRB5 1277 if (s->authctxt->krb5_ccname) 1278 child_set_env(&env, &envsize, "KRB5CCNAME", 1279 s->authctxt->krb5_ccname); 1280#endif 1281#ifdef USE_PAM 1282 /* 1283 * Pull in any environment variables that may have 1284 * been set by PAM. 1285 */ 1286 if (options.use_pam) { 1287 char **p; 1288 1289 p = fetch_pam_child_environment(); 1290 copy_environment(p, &env, &envsize); 1291 free_pam_environment(p); 1292 1293 p = fetch_pam_environment(); 1294 copy_environment(p, &env, &envsize); 1295 free_pam_environment(p); 1296 } 1297#endif /* USE_PAM */ 1298 1299 if (auth_sock_name != NULL) 1300 child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME, 1301 auth_sock_name); 1302 1303 /* read $HOME/.ssh/environment. */ 1304 if (options.permit_user_env && !options.use_login) { 1305 snprintf(buf, sizeof buf, "%.200s/.ssh/environment", 1306 strcmp(pw->pw_dir, "/") ? pw->pw_dir : ""); 1307 read_environment_file(&env, &envsize, buf); 1308 } 1309 if (debug_flag) { 1310 /* dump the environment */ 1311 fprintf(stderr, "Environment:\n"); 1312 for (i = 0; env[i]; i++) 1313 fprintf(stderr, " %.200s\n", env[i]); 1314 } 1315 return env; 1316} 1317 1318/* 1319 * Run $HOME/.ssh/rc, /etc/ssh/sshrc, or xauth (whichever is found 1320 * first in this order). 1321 */ 1322static void 1323do_rc_files(Session *s, const char *shell) 1324{ 1325 FILE *f = NULL; 1326 char cmd[1024]; 1327 int do_xauth; 1328 struct stat st; 1329 1330 do_xauth = 1331 s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL; 1332 1333 /* ignore _PATH_SSH_USER_RC for subsystems and admin forced commands */ 1334 if (!s->is_subsystem && options.adm_forced_command == NULL && 1335 !no_user_rc && stat(_PATH_SSH_USER_RC, &st) >= 0) { 1336 snprintf(cmd, sizeof cmd, "%s -c '%s %s'", 1337 shell, _PATH_BSHELL, _PATH_SSH_USER_RC); 1338 if (debug_flag) 1339 fprintf(stderr, "Running %s\n", cmd); 1340 f = popen(cmd, "w"); 1341 if (f) { 1342 if (do_xauth) 1343 fprintf(f, "%s %s\n", s->auth_proto, 1344 s->auth_data); 1345 pclose(f); 1346 } else 1347 fprintf(stderr, "Could not run %s\n", 1348 _PATH_SSH_USER_RC); 1349 } else if (stat(_PATH_SSH_SYSTEM_RC, &st) >= 0) { 1350 if (debug_flag) 1351 fprintf(stderr, "Running %s %s\n", _PATH_BSHELL, 1352 _PATH_SSH_SYSTEM_RC); 1353 f = popen(_PATH_BSHELL " " _PATH_SSH_SYSTEM_RC, "w"); 1354 if (f) { 1355 if (do_xauth) 1356 fprintf(f, "%s %s\n", s->auth_proto, 1357 s->auth_data); 1358 pclose(f); 1359 } else 1360 fprintf(stderr, "Could not run %s\n", 1361 _PATH_SSH_SYSTEM_RC); 1362 } else if (do_xauth && options.xauth_location != NULL) { 1363 /* Add authority data to .Xauthority if appropriate. */ 1364 if (debug_flag) { 1365 fprintf(stderr, 1366 "Running %.500s remove %.100s\n", 1367 options.xauth_location, s->auth_display); 1368 fprintf(stderr, 1369 "%.500s add %.100s %.100s %.100s\n", 1370 options.xauth_location, s->auth_display, 1371 s->auth_proto, s->auth_data); 1372 } 1373 snprintf(cmd, sizeof cmd, "%s -q -", 1374 options.xauth_location); 1375 f = popen(cmd, "w"); 1376 if (f) { 1377 fprintf(f, "remove %s\n", 1378 s->auth_display); 1379 fprintf(f, "add %s %s %s\n", 1380 s->auth_display, s->auth_proto, 1381 s->auth_data); 1382 pclose(f); 1383 } else { 1384 fprintf(stderr, "Could not run %s\n", 1385 cmd); 1386 } 1387 } 1388} 1389 1390static void 1391do_nologin(struct passwd *pw) 1392{ 1393 FILE *f = NULL; 1394 char buf[1024], *nl, *def_nl = _PATH_NOLOGIN; 1395 struct stat sb; 1396 1397#ifdef HAVE_LOGIN_CAP 1398 if (login_getcapbool(lc, "ignorenologin", 0) && pw->pw_uid) 1399 return; 1400 nl = login_getcapstr(lc, "nologin", def_nl, def_nl); 1401#else 1402 if (pw->pw_uid == 0) 1403 return; 1404 nl = def_nl; 1405#endif 1406 if (stat(nl, &sb) == -1) { 1407 if (nl != def_nl) 1408 xfree(nl); 1409 return; 1410 } 1411 1412 /* /etc/nologin exists. Print its contents if we can and exit. */ 1413 logit("User %.100s not allowed because %s exists", pw->pw_name, nl); 1414 if ((f = fopen(nl, "r")) != NULL) { 1415 while (fgets(buf, sizeof(buf), f)) 1416 fputs(buf, stderr); 1417 fclose(f); 1418 } 1419 exit(254); 1420} 1421 1422/* 1423 * Chroot into a directory after checking it for safety: all path components 1424 * must be root-owned directories with strict permissions. 1425 */ 1426static void 1427safely_chroot(const char *path, uid_t uid) 1428{ 1429 const char *cp; 1430 char component[MAXPATHLEN]; 1431 struct stat st; 1432 1433 if (*path != '/') 1434 fatal("chroot path does not begin at root"); 1435 if (strlen(path) >= sizeof(component)) 1436 fatal("chroot path too long"); 1437 1438 /* 1439 * Descend the path, checking that each component is a 1440 * root-owned directory with strict permissions. 1441 */ 1442 for (cp = path; cp != NULL;) { 1443 if ((cp = strchr(cp, '/')) == NULL) 1444 strlcpy(component, path, sizeof(component)); 1445 else { 1446 cp++; 1447 memcpy(component, path, cp - path); 1448 component[cp - path] = '\0'; 1449 } 1450 1451 debug3("%s: checking '%s'", __func__, component); 1452 1453 if (stat(component, &st) != 0) 1454 fatal("%s: stat(\"%s\"): %s", __func__, 1455 component, strerror(errno)); 1456 if (st.st_uid != 0 || (st.st_mode & 022) != 0) 1457 fatal("bad ownership or modes for chroot " 1458 "directory %s\"%s\"", 1459 cp == NULL ? "" : "component ", component); 1460 if (!S_ISDIR(st.st_mode)) 1461 fatal("chroot path %s\"%s\" is not a directory", 1462 cp == NULL ? "" : "component ", component); 1463 1464 } 1465 1466 if (chdir(path) == -1) 1467 fatal("Unable to chdir to chroot path \"%s\": " 1468 "%s", path, strerror(errno)); 1469 if (chroot(path) == -1) 1470 fatal("chroot(\"%s\"): %s", path, strerror(errno)); 1471 if (chdir("/") == -1) 1472 fatal("%s: chdir(/) after chroot: %s", 1473 __func__, strerror(errno)); 1474 verbose("Changed root directory to \"%s\"", path); 1475} 1476 1477/* Set login name, uid, gid, and groups. */ 1478void 1479do_setusercontext(struct passwd *pw) 1480{ 1481 char *chroot_path, *tmp; 1482 1483#ifdef WITH_SELINUX 1484 /* Cache selinux status for later use */ 1485 (void)ssh_selinux_enabled(); 1486#endif 1487 1488#ifndef HAVE_CYGWIN 1489 if (getuid() == 0 || geteuid() == 0) 1490#endif /* HAVE_CYGWIN */ 1491 { 1492#ifdef HAVE_LOGIN_CAP 1493# ifdef __bsdi__ 1494 setpgid(0, 0); 1495# endif 1496# ifdef USE_PAM 1497 if (options.use_pam) { 1498 do_pam_setcred(use_privsep); 1499 } 1500# endif /* USE_PAM */ 1501 if (setusercontext(lc, pw, pw->pw_uid, 1502 (LOGIN_SETALL & ~(LOGIN_SETENV|LOGIN_SETPATH|LOGIN_SETUSER))) < 0) { 1503 perror("unable to set user context"); 1504 exit(1); 1505 } 1506#else 1507# if defined(HAVE_GETLUID) && defined(HAVE_SETLUID) 1508 /* Sets login uid for accounting */ 1509 if (getluid() == -1 && setluid(pw->pw_uid) == -1) 1510 error("setluid: %s", strerror(errno)); 1511# endif /* defined(HAVE_GETLUID) && defined(HAVE_SETLUID) */ 1512 1513 if (setlogin(pw->pw_name) < 0) 1514 error("setlogin failed: %s", strerror(errno)); 1515 if (setgid(pw->pw_gid) < 0) { 1516 perror("setgid"); 1517 exit(1); 1518 } 1519 /* Initialize the group list. */ 1520 if (initgroups(pw->pw_name, pw->pw_gid) < 0) { 1521 perror("initgroups"); 1522 exit(1); 1523 } 1524 endgrent(); 1525# ifdef USE_PAM 1526 /* 1527 * PAM credentials may take the form of supplementary groups. 1528 * These will have been wiped by the above initgroups() call. 1529 * Reestablish them here. 1530 */ 1531 if (options.use_pam) { 1532 do_pam_setcred(use_privsep); 1533 } 1534# endif /* USE_PAM */ 1535# if defined(WITH_IRIX_PROJECT) || defined(WITH_IRIX_JOBS) || defined(WITH_IRIX_ARRAY) 1536 irix_setusercontext(pw); 1537# endif /* defined(WITH_IRIX_PROJECT) || defined(WITH_IRIX_JOBS) || defined(WITH_IRIX_ARRAY) */ 1538# ifdef _AIX 1539 aix_usrinfo(pw); 1540# endif /* _AIX */ 1541# ifdef USE_LIBIAF 1542 if (set_id(pw->pw_name) != 0) { 1543 exit(1); 1544 } 1545# endif /* USE_LIBIAF */ 1546#endif 1547#ifdef HAVE_SETPCRED 1548 /* 1549 * If we have a chroot directory, we set all creds except real 1550 * uid which we will need for chroot. If we don't have a 1551 * chroot directory, we don't override anything. 1552 */ 1553 { 1554 char **creds = NULL, *chroot_creds[] = 1555 { "REAL_USER=root", NULL }; 1556 1557 if (options.chroot_directory != NULL && 1558 strcasecmp(options.chroot_directory, "none") != 0) 1559 creds = chroot_creds; 1560 1561 if (setpcred(pw->pw_name, creds) == -1) 1562 fatal("Failed to set process credentials"); 1563 } 1564#endif /* HAVE_SETPCRED */ 1565 1566#ifdef WITH_SELINUX 1567 ssh_selinux_setup_exec_context(pw->pw_name); 1568#endif 1569 1570 if (options.chroot_directory != NULL && 1571 strcasecmp(options.chroot_directory, "none") != 0) { 1572 tmp = tilde_expand_filename(options.chroot_directory, 1573 pw->pw_uid); 1574 chroot_path = percent_expand(tmp, "h", pw->pw_dir, 1575 "u", pw->pw_name, (char *)NULL); 1576 safely_chroot(chroot_path, pw->pw_uid); 1577 free(tmp); 1578 free(chroot_path); 1579 } 1580 1581#ifdef HAVE_LOGIN_CAP 1582 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUSER) < 0) { 1583 perror("unable to set user context (setuser)"); 1584 exit(1); 1585 } 1586#else 1587 /* Permanently switch to the desired uid. */ 1588 permanently_set_uid(pw); 1589#endif 1590 } 1591 1592 if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) 1593 fatal("Failed to set uids to %u.", (u_int) pw->pw_uid); 1594} 1595 1596static void 1597do_pwchange(Session *s) 1598{ 1599 fflush(NULL); 1600 fprintf(stderr, "WARNING: Your password has expired.\n"); 1601 if (s->ttyfd != -1) { 1602 fprintf(stderr, 1603 "You must change your password now and login again!\n"); 1604#ifdef PASSWD_NEEDS_USERNAME 1605 execl(_PATH_PASSWD_PROG, "passwd", s->pw->pw_name, 1606 (char *)NULL); 1607#else 1608 execl(_PATH_PASSWD_PROG, "passwd", (char *)NULL); 1609#endif 1610 perror("passwd"); 1611 } else { 1612 fprintf(stderr, 1613 "Password change required but no TTY available.\n"); 1614 } 1615 exit(1); 1616} 1617 1618static void 1619launch_login(struct passwd *pw, const char *hostname) 1620{ 1621 /* Launch login(1). */ 1622 1623 execl(LOGIN_PROGRAM, "login", "-h", hostname, 1624#ifdef xxxLOGIN_NEEDS_TERM 1625 (s->term ? s->term : "unknown"), 1626#endif /* LOGIN_NEEDS_TERM */ 1627#ifdef LOGIN_NO_ENDOPT 1628 "-p", "-f", pw->pw_name, (char *)NULL); 1629#else 1630 "-p", "-f", "--", pw->pw_name, (char *)NULL); 1631#endif 1632 1633 /* Login couldn't be executed, die. */ 1634 1635 perror("login"); 1636 exit(1); 1637} 1638 1639static void 1640child_close_fds(void) 1641{ 1642 int i; 1643 1644 if (packet_get_connection_in() == packet_get_connection_out()) 1645 close(packet_get_connection_in()); 1646 else { 1647 close(packet_get_connection_in()); 1648 close(packet_get_connection_out()); 1649 } 1650 /* 1651 * Close all descriptors related to channels. They will still remain 1652 * open in the parent. 1653 */ 1654 /* XXX better use close-on-exec? -markus */ 1655 channel_close_all(); 1656 1657 /* 1658 * Close any extra file descriptors. Note that there may still be 1659 * descriptors left by system functions. They will be closed later. 1660 */ 1661 endpwent(); 1662 1663 /* 1664 * Close any extra open file descriptors so that we don't have them 1665 * hanging around in clients. Note that we want to do this after 1666 * initgroups, because at least on Solaris 2.3 it leaves file 1667 * descriptors open. 1668 */ 1669 for (i = 3; i < 64; i++) 1670 close(i); 1671} 1672 1673/* 1674 * Performs common processing for the child, such as setting up the 1675 * environment, closing extra file descriptors, setting the user and group 1676 * ids, and executing the command or shell. 1677 */ 1678#define ARGV_MAX 10 1679void 1680do_child(Session *s, const char *command) 1681{ 1682 extern char **environ; 1683 char **env; 1684 char *argv[ARGV_MAX]; 1685 const char *shell, *shell0, *hostname = NULL; 1686 struct passwd *pw = s->pw; 1687 int r = 0; 1688 1689 /* remove hostkey from the child's memory */ 1690 destroy_sensitive_data(); 1691 1692 /* Force a password change */ 1693 if (s->authctxt->force_pwchange) { 1694 do_setusercontext(pw); 1695 child_close_fds(); 1696 do_pwchange(s); 1697 exit(1); 1698 } 1699 1700 /* login(1) is only called if we execute the login shell */ 1701 if (options.use_login && command != NULL) 1702 options.use_login = 0; 1703 1704#ifdef _UNICOS 1705 cray_setup(pw->pw_uid, pw->pw_name, command); 1706#endif /* _UNICOS */ 1707 1708 /* 1709 * Login(1) does this as well, and it needs uid 0 for the "-h" 1710 * switch, so we let login(1) to this for us. 1711 */ 1712 if (!options.use_login) { 1713#ifdef HAVE_OSF_SIA 1714 session_setup_sia(pw, s->ttyfd == -1 ? NULL : s->tty); 1715 if (!check_quietlogin(s, command)) 1716 do_motd(); 1717#else /* HAVE_OSF_SIA */ 1718 /* When PAM is enabled we rely on it to do the nologin check */ 1719 if (!options.use_pam) 1720 do_nologin(pw); 1721 do_setusercontext(pw); 1722 /* 1723 * PAM session modules in do_setusercontext may have 1724 * generated messages, so if this in an interactive 1725 * login then display them too. 1726 */ 1727 if (!check_quietlogin(s, command)) 1728 display_loginmsg(); 1729#endif /* HAVE_OSF_SIA */ 1730 } 1731 1732#ifdef USE_PAM 1733 if (options.use_pam && !options.use_login && !is_pam_session_open()) { 1734 debug3("PAM session not opened, exiting"); 1735 display_loginmsg(); 1736 exit(254); 1737 } 1738#endif 1739 1740 /* 1741 * Get the shell from the password data. An empty shell field is 1742 * legal, and means /bin/sh. 1743 */ 1744 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; 1745 1746 /* 1747 * Make sure $SHELL points to the shell from the password file, 1748 * even if shell is overridden from login.conf 1749 */ 1750 env = do_setup_env(s, shell); 1751 1752#ifdef HAVE_LOGIN_CAP 1753 shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell); 1754#endif 1755 1756 /* we have to stash the hostname before we close our socket. */ 1757 if (options.use_login) 1758 hostname = get_remote_name_or_ip(utmp_len, 1759 options.use_dns); 1760 /* 1761 * Close the connection descriptors; note that this is the child, and 1762 * the server will still have the socket open, and it is important 1763 * that we do not shutdown it. Note that the descriptors cannot be 1764 * closed before building the environment, as we call 1765 * get_remote_ipaddr there. 1766 */ 1767 child_close_fds(); 1768 1769 /* 1770 * Must take new environment into use so that .ssh/rc, 1771 * /etc/ssh/sshrc and xauth are run in the proper environment. 1772 */ 1773 environ = env; 1774 1775#if defined(KRB5) && defined(USE_AFS) 1776 /* 1777 * At this point, we check to see if AFS is active and if we have 1778 * a valid Kerberos 5 TGT. If so, it seems like a good idea to see 1779 * if we can (and need to) extend the ticket into an AFS token. If 1780 * we don't do this, we run into potential problems if the user's 1781 * home directory is in AFS and it's not world-readable. 1782 */ 1783 1784 if (options.kerberos_get_afs_token && k_hasafs() && 1785 (s->authctxt->krb5_ctx != NULL)) { 1786 char cell[64]; 1787 1788 debug("Getting AFS token"); 1789 1790 k_setpag(); 1791 1792 if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0) 1793 krb5_afslog(s->authctxt->krb5_ctx, 1794 s->authctxt->krb5_fwd_ccache, cell, NULL); 1795 1796 krb5_afslog_home(s->authctxt->krb5_ctx, 1797 s->authctxt->krb5_fwd_ccache, NULL, NULL, pw->pw_dir); 1798 } 1799#endif 1800 1801 /* Change current directory to the user's home directory. */ 1802 if (chdir(pw->pw_dir) < 0) { 1803 /* Suppress missing homedir warning for chroot case */ 1804#ifdef HAVE_LOGIN_CAP 1805 r = login_getcapbool(lc, "requirehome", 0); 1806#endif 1807 if (r || options.chroot_directory == NULL) 1808 fprintf(stderr, "Could not chdir to home " 1809 "directory %s: %s\n", pw->pw_dir, 1810 strerror(errno)); 1811 if (r) 1812 exit(1); 1813 } 1814 1815 closefrom(STDERR_FILENO + 1); 1816 1817 if (!options.use_login) 1818 do_rc_files(s, shell); 1819 1820 /* restore SIGPIPE for child */ 1821 signal(SIGPIPE, SIG_DFL); 1822 1823 if (s->is_subsystem == SUBSYSTEM_INT_SFTP_ERROR) { 1824 printf("This service allows sftp connections only.\n"); 1825 fflush(NULL); 1826 exit(1); 1827 } else if (s->is_subsystem == SUBSYSTEM_INT_SFTP) { 1828 extern int optind, optreset; 1829 int i; 1830 char *p, *args; 1831 1832 setproctitle("%s@%s", s->pw->pw_name, INTERNAL_SFTP_NAME); 1833 args = xstrdup(command ? command : "sftp-server"); 1834 for (i = 0, (p = strtok(args, " ")); p; (p = strtok(NULL, " "))) 1835 if (i < ARGV_MAX - 1) 1836 argv[i++] = p; 1837 argv[i] = NULL; 1838 optind = optreset = 1; 1839 __progname = argv[0]; 1840#ifdef WITH_SELINUX 1841 ssh_selinux_change_context("sftpd_t"); 1842#endif 1843 exit(sftp_server_main(i, argv, s->pw)); 1844 } 1845 1846 fflush(NULL); 1847 1848 if (options.use_login) { 1849 launch_login(pw, hostname); 1850 /* NEVERREACHED */ 1851 } 1852 1853 /* Get the last component of the shell name. */ 1854 if ((shell0 = strrchr(shell, '/')) != NULL) 1855 shell0++; 1856 else 1857 shell0 = shell; 1858 1859 /* 1860 * If we have no command, execute the shell. In this case, the shell 1861 * name to be passed in argv[0] is preceded by '-' to indicate that 1862 * this is a login shell. 1863 */ 1864 if (!command) { 1865 char argv0[256]; 1866 1867 /* Start the shell. Set initial character to '-'. */ 1868 argv0[0] = '-'; 1869 1870 if (strlcpy(argv0 + 1, shell0, sizeof(argv0) - 1) 1871 >= sizeof(argv0) - 1) { 1872 errno = EINVAL; 1873 perror(shell); 1874 exit(1); 1875 } 1876 1877 /* Execute the shell. */ 1878 argv[0] = argv0; 1879 argv[1] = NULL; 1880 execve(shell, argv, env); 1881 1882 /* Executing the shell failed. */ 1883 perror(shell); 1884 exit(1); 1885 } 1886 /* 1887 * Execute the command using the user's shell. This uses the -c 1888 * option to execute the command. 1889 */ 1890 argv[0] = (char *) shell0; 1891 argv[1] = "-c"; 1892 argv[2] = (char *) command; 1893 argv[3] = NULL; 1894 execve(shell, argv, env); 1895 perror(shell); 1896 exit(1); 1897} 1898 1899void 1900session_unused(int id) 1901{ 1902 debug3("%s: session id %d unused", __func__, id); 1903 if (id >= options.max_sessions || 1904 id >= sessions_nalloc) { 1905 fatal("%s: insane session id %d (max %d nalloc %d)", 1906 __func__, id, options.max_sessions, sessions_nalloc); 1907 } 1908 bzero(&sessions[id], sizeof(*sessions)); 1909 sessions[id].self = id; 1910 sessions[id].used = 0; 1911 sessions[id].chanid = -1; 1912 sessions[id].ptyfd = -1; 1913 sessions[id].ttyfd = -1; 1914 sessions[id].ptymaster = -1; 1915 sessions[id].x11_chanids = NULL; 1916 sessions[id].next_unused = sessions_first_unused; 1917 sessions_first_unused = id; 1918} 1919 1920Session * 1921session_new(void) 1922{ 1923 Session *s, *tmp; 1924 1925 if (sessions_first_unused == -1) { 1926 if (sessions_nalloc >= options.max_sessions) 1927 return NULL; 1928 debug2("%s: allocate (allocated %d max %d)", 1929 __func__, sessions_nalloc, options.max_sessions); 1930 tmp = xrealloc(sessions, sessions_nalloc + 1, 1931 sizeof(*sessions)); 1932 if (tmp == NULL) { 1933 error("%s: cannot allocate %d sessions", 1934 __func__, sessions_nalloc + 1); 1935 return NULL; 1936 } 1937 sessions = tmp; 1938 session_unused(sessions_nalloc++); 1939 } 1940 1941 if (sessions_first_unused >= sessions_nalloc || 1942 sessions_first_unused < 0) { 1943 fatal("%s: insane first_unused %d max %d nalloc %d", 1944 __func__, sessions_first_unused, options.max_sessions, 1945 sessions_nalloc); 1946 } 1947 1948 s = &sessions[sessions_first_unused]; 1949 if (s->used) { 1950 fatal("%s: session %d already used", 1951 __func__, sessions_first_unused); 1952 } 1953 sessions_first_unused = s->next_unused; 1954 s->used = 1; 1955 s->next_unused = -1; 1956 debug("session_new: session %d", s->self); 1957 1958 return s; 1959} 1960 1961static void 1962session_dump(void) 1963{ 1964 int i; 1965 for (i = 0; i < sessions_nalloc; i++) { 1966 Session *s = &sessions[i]; 1967 1968 debug("dump: used %d next_unused %d session %d %p " 1969 "channel %d pid %ld", 1970 s->used, 1971 s->next_unused, 1972 s->self, 1973 s, 1974 s->chanid, 1975 (long)s->pid); 1976 } 1977} 1978 1979int 1980session_open(Authctxt *authctxt, int chanid) 1981{ 1982 Session *s = session_new(); 1983 debug("session_open: channel %d", chanid); 1984 if (s == NULL) { 1985 error("no more sessions"); 1986 return 0; 1987 } 1988 s->authctxt = authctxt; 1989 s->pw = authctxt->pw; 1990 if (s->pw == NULL || !authctxt->valid) 1991 fatal("no user for session %d", s->self); 1992 debug("session_open: session %d: link with channel %d", s->self, chanid); 1993 s->chanid = chanid; 1994 return 1; 1995} 1996 1997Session * 1998session_by_tty(char *tty) 1999{ 2000 int i; 2001 for (i = 0; i < sessions_nalloc; i++) { 2002 Session *s = &sessions[i]; 2003 if (s->used && s->ttyfd != -1 && strcmp(s->tty, tty) == 0) { 2004 debug("session_by_tty: session %d tty %s", i, tty); 2005 return s; 2006 } 2007 } 2008 debug("session_by_tty: unknown tty %.100s", tty); 2009 session_dump(); 2010 return NULL; 2011} 2012 2013static Session * 2014session_by_channel(int id) 2015{ 2016 int i; 2017 for (i = 0; i < sessions_nalloc; i++) { 2018 Session *s = &sessions[i]; 2019 if (s->used && s->chanid == id) { 2020 debug("session_by_channel: session %d channel %d", 2021 i, id); 2022 return s; 2023 } 2024 } 2025 debug("session_by_channel: unknown channel %d", id); 2026 session_dump(); 2027 return NULL; 2028} 2029 2030static Session * 2031session_by_x11_channel(int id) 2032{ 2033 int i, j; 2034 2035 for (i = 0; i < sessions_nalloc; i++) { 2036 Session *s = &sessions[i]; 2037 2038 if (s->x11_chanids == NULL || !s->used) 2039 continue; 2040 for (j = 0; s->x11_chanids[j] != -1; j++) { 2041 if (s->x11_chanids[j] == id) { 2042 debug("session_by_x11_channel: session %d " 2043 "channel %d", s->self, id); 2044 return s; 2045 } 2046 } 2047 } 2048 debug("session_by_x11_channel: unknown channel %d", id); 2049 session_dump(); 2050 return NULL; 2051} 2052 2053static Session * 2054session_by_pid(pid_t pid) 2055{ 2056 int i; 2057 debug("session_by_pid: pid %ld", (long)pid); 2058 for (i = 0; i < sessions_nalloc; i++) { 2059 Session *s = &sessions[i]; 2060 if (s->used && s->pid == pid) 2061 return s; 2062 } 2063 error("session_by_pid: unknown pid %ld", (long)pid); 2064 session_dump(); 2065 return NULL; 2066} 2067 2068static int 2069session_window_change_req(Session *s) 2070{ 2071 s->col = packet_get_int(); 2072 s->row = packet_get_int(); 2073 s->xpixel = packet_get_int(); 2074 s->ypixel = packet_get_int(); 2075 packet_check_eom(); 2076 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 2077 return 1; 2078} 2079 2080static int 2081session_pty_req(Session *s) 2082{ 2083 u_int len; 2084 int n_bytes; 2085 2086 if (no_pty_flag) { 2087 debug("Allocating a pty not permitted for this authentication."); 2088 return 0; 2089 } 2090 if (s->ttyfd != -1) { 2091 packet_disconnect("Protocol error: you already have a pty."); 2092 return 0; 2093 } 2094 2095 s->term = packet_get_string(&len); 2096 2097 if (compat20) { 2098 s->col = packet_get_int(); 2099 s->row = packet_get_int(); 2100 } else { 2101 s->row = packet_get_int(); 2102 s->col = packet_get_int(); 2103 } 2104 s->xpixel = packet_get_int(); 2105 s->ypixel = packet_get_int(); 2106 2107 if (strcmp(s->term, "") == 0) { 2108 xfree(s->term); 2109 s->term = NULL; 2110 } 2111 2112 /* Allocate a pty and open it. */ 2113 debug("Allocating pty."); 2114 if (!PRIVSEP(pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, 2115 sizeof(s->tty)))) { 2116 if (s->term) 2117 xfree(s->term); 2118 s->term = NULL; 2119 s->ptyfd = -1; 2120 s->ttyfd = -1; 2121 error("session_pty_req: session %d alloc failed", s->self); 2122 return 0; 2123 } 2124 debug("session_pty_req: session %d alloc %s", s->self, s->tty); 2125 2126 /* for SSH1 the tty modes length is not given */ 2127 if (!compat20) 2128 n_bytes = packet_remaining(); 2129 tty_parse_modes(s->ttyfd, &n_bytes); 2130 2131 if (!use_privsep) 2132 pty_setowner(s->pw, s->tty); 2133 2134 /* Set window size from the packet. */ 2135 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 2136 2137 packet_check_eom(); 2138 session_proctitle(s); 2139 return 1; 2140} 2141 2142static int 2143session_subsystem_req(Session *s) 2144{ 2145 struct stat st; 2146 u_int len; 2147 int success = 0; 2148 char *prog, *cmd, *subsys = packet_get_string(&len); 2149 u_int i; 2150 2151 packet_check_eom(); 2152 logit("subsystem request for %.100s", subsys); 2153 2154 for (i = 0; i < options.num_subsystems; i++) { 2155 if (strcmp(subsys, options.subsystem_name[i]) == 0) { 2156 prog = options.subsystem_command[i]; 2157 cmd = options.subsystem_args[i]; 2158 if (strcmp(INTERNAL_SFTP_NAME, prog) == 0) { 2159 s->is_subsystem = SUBSYSTEM_INT_SFTP; 2160 debug("subsystem: %s", prog); 2161 } else { 2162 if (stat(prog, &st) < 0) 2163 debug("subsystem: cannot stat %s: %s", 2164 prog, strerror(errno)); 2165 s->is_subsystem = SUBSYSTEM_EXT; 2166 debug("subsystem: exec() %s", cmd); 2167 } 2168 success = do_exec(s, cmd) == 0; 2169 break; 2170 } 2171 } 2172 2173 if (!success) 2174 logit("subsystem request for %.100s failed, subsystem not found", 2175 subsys); 2176 2177 xfree(subsys); 2178 return success; 2179} 2180 2181static int 2182session_x11_req(Session *s) 2183{ 2184 int success; 2185 2186 if (s->auth_proto != NULL || s->auth_data != NULL) { 2187 error("session_x11_req: session %d: " 2188 "x11 forwarding already active", s->self); 2189 return 0; 2190 } 2191 s->single_connection = packet_get_char(); 2192 s->auth_proto = packet_get_string(NULL); 2193 s->auth_data = packet_get_string(NULL); 2194 s->screen = packet_get_int(); 2195 packet_check_eom(); 2196 2197 success = session_setup_x11fwd(s); 2198 if (!success) { 2199 xfree(s->auth_proto); 2200 xfree(s->auth_data); 2201 s->auth_proto = NULL; 2202 s->auth_data = NULL; 2203 } 2204 return success; 2205} 2206 2207static int 2208session_shell_req(Session *s) 2209{ 2210 packet_check_eom(); 2211 return do_exec(s, NULL) == 0; 2212} 2213 2214static int 2215session_exec_req(Session *s) 2216{ 2217 u_int len, success; 2218 2219 char *command = packet_get_string(&len); 2220 packet_check_eom(); 2221 success = do_exec(s, command) == 0; 2222 xfree(command); 2223 return success; 2224} 2225 2226static int 2227session_break_req(Session *s) 2228{ 2229 2230 packet_get_int(); /* ignored */ 2231 packet_check_eom(); 2232 2233 if (s->ttyfd == -1 || tcsendbreak(s->ttyfd, 0) < 0) 2234 return 0; 2235 return 1; 2236} 2237 2238static int 2239session_env_req(Session *s) 2240{ 2241 char *name, *val; 2242 u_int name_len, val_len, i; 2243 2244 name = packet_get_string(&name_len); 2245 val = packet_get_string(&val_len); 2246 packet_check_eom(); 2247 2248 /* Don't set too many environment variables */ 2249 if (s->num_env > 128) { 2250 debug2("Ignoring env request %s: too many env vars", name); 2251 goto fail; 2252 } 2253 2254 for (i = 0; i < options.num_accept_env; i++) { 2255 if (match_pattern(name, options.accept_env[i])) { 2256 debug2("Setting env %d: %s=%s", s->num_env, name, val); 2257 s->env = xrealloc(s->env, s->num_env + 1, 2258 sizeof(*s->env)); 2259 s->env[s->num_env].name = name; 2260 s->env[s->num_env].val = val; 2261 s->num_env++; 2262 return (1); 2263 } 2264 } 2265 debug2("Ignoring env request %s: disallowed name", name); 2266 2267 fail: 2268 xfree(name); 2269 xfree(val); 2270 return (0); 2271} 2272 2273static int 2274session_auth_agent_req(Session *s) 2275{ 2276 static int called = 0; 2277 packet_check_eom(); 2278 if (no_agent_forwarding_flag || !options.allow_agent_forwarding) { 2279 debug("session_auth_agent_req: no_agent_forwarding_flag"); 2280 return 0; 2281 } 2282 if (called) { 2283 return 0; 2284 } else { 2285 called = 1; 2286 return auth_input_request_forwarding(s->pw); 2287 } 2288} 2289 2290int 2291session_input_channel_req(Channel *c, const char *rtype) 2292{ 2293 int success = 0; 2294 Session *s; 2295 2296 if ((s = session_by_channel(c->self)) == NULL) { 2297 logit("session_input_channel_req: no session %d req %.100s", 2298 c->self, rtype); 2299 return 0; 2300 } 2301 debug("session_input_channel_req: session %d req %s", s->self, rtype); 2302 2303 /* 2304 * a session is in LARVAL state until a shell, a command 2305 * or a subsystem is executed 2306 */ 2307 if (c->type == SSH_CHANNEL_LARVAL) { 2308 if (strcmp(rtype, "shell") == 0) { 2309 success = session_shell_req(s); 2310 } else if (strcmp(rtype, "exec") == 0) { 2311 success = session_exec_req(s); 2312 } else if (strcmp(rtype, "pty-req") == 0) { 2313 success = session_pty_req(s); 2314 } else if (strcmp(rtype, "x11-req") == 0) { 2315 success = session_x11_req(s); 2316 } else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) { 2317 success = session_auth_agent_req(s); 2318 } else if (strcmp(rtype, "subsystem") == 0) { 2319 success = session_subsystem_req(s); 2320 } else if (strcmp(rtype, "env") == 0) { 2321 success = session_env_req(s); 2322 } 2323 } 2324 if (strcmp(rtype, "window-change") == 0) { 2325 success = session_window_change_req(s); 2326 } else if (strcmp(rtype, "break") == 0) { 2327 success = session_break_req(s); 2328 } 2329 2330 return success; 2331} 2332 2333void 2334session_set_fds(Session *s, int fdin, int fdout, int fderr, int is_tty) 2335{ 2336 if (!compat20) 2337 fatal("session_set_fds: called for proto != 2.0"); 2338 /* 2339 * now that have a child and a pipe to the child, 2340 * we can activate our channel and register the fd's 2341 */ 2342 if (s->chanid == -1) 2343 fatal("no channel for session %d", s->self); 2344 channel_set_fds(s->chanid, 2345 fdout, fdin, fderr, 2346 fderr == -1 ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ, 2347 1, is_tty, CHAN_SES_WINDOW_DEFAULT); 2348} 2349 2350/* 2351 * Function to perform pty cleanup. Also called if we get aborted abnormally 2352 * (e.g., due to a dropped connection). 2353 */ 2354void 2355session_pty_cleanup2(Session *s) 2356{ 2357 if (s == NULL) { 2358 error("session_pty_cleanup: no session"); 2359 return; 2360 } 2361 if (s->ttyfd == -1) 2362 return; 2363 2364 debug("session_pty_cleanup: session %d release %s", s->self, s->tty); 2365 2366 /* Record that the user has logged out. */ 2367 if (s->pid != 0) 2368 record_logout(s->pid, s->tty, s->pw->pw_name); 2369 2370 /* Release the pseudo-tty. */ 2371 if (getuid() == 0) 2372 pty_release(s->tty); 2373 2374 /* 2375 * Close the server side of the socket pairs. We must do this after 2376 * the pty cleanup, so that another process doesn't get this pty 2377 * while we're still cleaning up. 2378 */ 2379 if (s->ptymaster != -1 && close(s->ptymaster) < 0) 2380 error("close(s->ptymaster/%d): %s", 2381 s->ptymaster, strerror(errno)); 2382 2383 /* unlink pty from session */ 2384 s->ttyfd = -1; 2385} 2386 2387void 2388session_pty_cleanup(Session *s) 2389{ 2390 PRIVSEP(session_pty_cleanup2(s)); 2391} 2392 2393static char * 2394sig2name(int sig) 2395{ 2396#define SSH_SIG(x) if (sig == SIG ## x) return #x 2397 SSH_SIG(ABRT); 2398 SSH_SIG(ALRM); 2399 SSH_SIG(FPE); 2400 SSH_SIG(HUP); 2401 SSH_SIG(ILL); 2402 SSH_SIG(INT); 2403 SSH_SIG(KILL); 2404 SSH_SIG(PIPE); 2405 SSH_SIG(QUIT); 2406 SSH_SIG(SEGV); 2407 SSH_SIG(TERM); 2408 SSH_SIG(USR1); 2409 SSH_SIG(USR2); 2410#undef SSH_SIG 2411 return "SIG@openssh.com"; 2412} 2413 2414static void 2415session_close_x11(int id) 2416{ 2417 Channel *c; 2418 2419 if ((c = channel_by_id(id)) == NULL) { 2420 debug("session_close_x11: x11 channel %d missing", id); 2421 } else { 2422 /* Detach X11 listener */ 2423 debug("session_close_x11: detach x11 channel %d", id); 2424 channel_cancel_cleanup(id); 2425 if (c->ostate != CHAN_OUTPUT_CLOSED) 2426 chan_mark_dead(c); 2427 } 2428} 2429 2430static void 2431session_close_single_x11(int id, void *arg) 2432{ 2433 Session *s; 2434 u_int i; 2435 2436 debug3("session_close_single_x11: channel %d", id); 2437 channel_cancel_cleanup(id); 2438 if ((s = session_by_x11_channel(id)) == NULL) 2439 fatal("session_close_single_x11: no x11 channel %d", id); 2440 for (i = 0; s->x11_chanids[i] != -1; i++) { 2441 debug("session_close_single_x11: session %d: " 2442 "closing channel %d", s->self, s->x11_chanids[i]); 2443 /* 2444 * The channel "id" is already closing, but make sure we 2445 * close all of its siblings. 2446 */ 2447 if (s->x11_chanids[i] != id) 2448 session_close_x11(s->x11_chanids[i]); 2449 } 2450 xfree(s->x11_chanids); 2451 s->x11_chanids = NULL; 2452 if (s->display) { 2453 xfree(s->display); 2454 s->display = NULL; 2455 } 2456 if (s->auth_proto) { 2457 xfree(s->auth_proto); 2458 s->auth_proto = NULL; 2459 } 2460 if (s->auth_data) { 2461 xfree(s->auth_data); 2462 s->auth_data = NULL; 2463 } 2464 if (s->auth_display) { 2465 xfree(s->auth_display); 2466 s->auth_display = NULL; 2467 } 2468} 2469 2470static void 2471session_exit_message(Session *s, int status) 2472{ 2473 Channel *c; 2474 2475 if ((c = channel_lookup(s->chanid)) == NULL) 2476 fatal("session_exit_message: session %d: no channel %d", 2477 s->self, s->chanid); 2478 debug("session_exit_message: session %d channel %d pid %ld", 2479 s->self, s->chanid, (long)s->pid); 2480 2481 if (WIFEXITED(status)) { 2482 channel_request_start(s->chanid, "exit-status", 0); 2483 packet_put_int(WEXITSTATUS(status)); 2484 packet_send(); 2485 } else if (WIFSIGNALED(status)) { 2486 channel_request_start(s->chanid, "exit-signal", 0); 2487 packet_put_cstring(sig2name(WTERMSIG(status))); 2488#ifdef WCOREDUMP 2489 packet_put_char(WCOREDUMP(status)? 1 : 0); 2490#else /* WCOREDUMP */ 2491 packet_put_char(0); 2492#endif /* WCOREDUMP */ 2493 packet_put_cstring(""); 2494 packet_put_cstring(""); 2495 packet_send(); 2496 } else { 2497 /* Some weird exit cause. Just exit. */ 2498 packet_disconnect("wait returned status %04x.", status); 2499 } 2500 2501 /* disconnect channel */ 2502 debug("session_exit_message: release channel %d", s->chanid); 2503 2504 /* 2505 * Adjust cleanup callback attachment to send close messages when 2506 * the channel gets EOF. The session will be then be closed 2507 * by session_close_by_channel when the childs close their fds. 2508 */ 2509 channel_register_cleanup(c->self, session_close_by_channel, 1); 2510 2511 /* 2512 * emulate a write failure with 'chan_write_failed', nobody will be 2513 * interested in data we write. 2514 * Note that we must not call 'chan_read_failed', since there could 2515 * be some more data waiting in the pipe. 2516 */ 2517 if (c->ostate != CHAN_OUTPUT_CLOSED) 2518 chan_write_failed(c); 2519} 2520 2521void 2522session_close(Session *s) 2523{ 2524 u_int i; 2525 2526 debug("session_close: session %d pid %ld", s->self, (long)s->pid); 2527 if (s->ttyfd != -1) 2528 session_pty_cleanup(s); 2529 if (s->term) 2530 xfree(s->term); 2531 if (s->display) 2532 xfree(s->display); 2533 if (s->x11_chanids) 2534 xfree(s->x11_chanids); 2535 if (s->auth_display) 2536 xfree(s->auth_display); 2537 if (s->auth_data) 2538 xfree(s->auth_data); 2539 if (s->auth_proto) 2540 xfree(s->auth_proto); 2541 if (s->env != NULL) { 2542 for (i = 0; i < s->num_env; i++) { 2543 xfree(s->env[i].name); 2544 xfree(s->env[i].val); 2545 } 2546 xfree(s->env); 2547 } 2548 session_proctitle(s); 2549 session_unused(s->self); 2550} 2551 2552void 2553session_close_by_pid(pid_t pid, int status) 2554{ 2555 Session *s = session_by_pid(pid); 2556 if (s == NULL) { 2557 debug("session_close_by_pid: no session for pid %ld", 2558 (long)pid); 2559 return; 2560 } 2561 if (s->chanid != -1) 2562 session_exit_message(s, status); 2563 if (s->ttyfd != -1) 2564 session_pty_cleanup(s); 2565 s->pid = 0; 2566} 2567 2568/* 2569 * this is called when a channel dies before 2570 * the session 'child' itself dies 2571 */ 2572void 2573session_close_by_channel(int id, void *arg) 2574{ 2575 Session *s = session_by_channel(id); 2576 u_int i; 2577 2578 if (s == NULL) { 2579 debug("session_close_by_channel: no session for id %d", id); 2580 return; 2581 } 2582 debug("session_close_by_channel: channel %d child %ld", 2583 id, (long)s->pid); 2584 if (s->pid != 0) { 2585 debug("session_close_by_channel: channel %d: has child", id); 2586 /* 2587 * delay detach of session, but release pty, since 2588 * the fd's to the child are already closed 2589 */ 2590 if (s->ttyfd != -1) 2591 session_pty_cleanup(s); 2592 return; 2593 } 2594 /* detach by removing callback */ 2595 channel_cancel_cleanup(s->chanid); 2596 2597 /* Close any X11 listeners associated with this session */ 2598 if (s->x11_chanids != NULL) { 2599 for (i = 0; s->x11_chanids[i] != -1; i++) { 2600 session_close_x11(s->x11_chanids[i]); 2601 s->x11_chanids[i] = -1; 2602 } 2603 } 2604 2605 s->chanid = -1; 2606 session_close(s); 2607} 2608 2609void 2610session_destroy_all(void (*closefunc)(Session *)) 2611{ 2612 int i; 2613 for (i = 0; i < sessions_nalloc; i++) { 2614 Session *s = &sessions[i]; 2615 if (s->used) { 2616 if (closefunc != NULL) 2617 closefunc(s); 2618 else 2619 session_close(s); 2620 } 2621 } 2622} 2623 2624static char * 2625session_tty_list(void) 2626{ 2627 static char buf[1024]; 2628 int i; 2629 char *cp; 2630 2631 buf[0] = '\0'; 2632 for (i = 0; i < sessions_nalloc; i++) { 2633 Session *s = &sessions[i]; 2634 if (s->used && s->ttyfd != -1) { 2635 2636 if (strncmp(s->tty, "/dev/", 5) != 0) { 2637 cp = strrchr(s->tty, '/'); 2638 cp = (cp == NULL) ? s->tty : cp + 1; 2639 } else 2640 cp = s->tty + 5; 2641 2642 if (buf[0] != '\0') 2643 strlcat(buf, ",", sizeof buf); 2644 strlcat(buf, cp, sizeof buf); 2645 } 2646 } 2647 if (buf[0] == '\0') 2648 strlcpy(buf, "notty", sizeof buf); 2649 return buf; 2650} 2651 2652void 2653session_proctitle(Session *s) 2654{ 2655 if (s->pw == NULL) 2656 error("no user for session %d", s->self); 2657 else 2658 setproctitle("%s@%s", s->pw->pw_name, session_tty_list()); 2659} 2660 2661int 2662session_setup_x11fwd(Session *s) 2663{ 2664 struct stat st; 2665 char display[512], auth_display[512]; 2666 char hostname[MAXHOSTNAMELEN]; 2667 u_int i; 2668 2669 if (no_x11_forwarding_flag) { 2670 packet_send_debug("X11 forwarding disabled in user configuration file."); 2671 return 0; 2672 } 2673 if (!options.x11_forwarding) { 2674 debug("X11 forwarding disabled in server configuration file."); 2675 return 0; 2676 } 2677 if (!options.xauth_location || 2678 (stat(options.xauth_location, &st) == -1)) { 2679 packet_send_debug("No xauth program; cannot forward with spoofing."); 2680 return 0; 2681 } 2682 if (options.use_login) { 2683 packet_send_debug("X11 forwarding disabled; " 2684 "not compatible with UseLogin=yes."); 2685 return 0; 2686 } 2687 if (s->display != NULL) { 2688 debug("X11 display already set."); 2689 return 0; 2690 } 2691 if (x11_create_display_inet(options.x11_display_offset, 2692 options.x11_use_localhost, s->single_connection, 2693 &s->display_number, &s->x11_chanids) == -1) { 2694 debug("x11_create_display_inet failed."); 2695 return 0; 2696 } 2697 for (i = 0; s->x11_chanids[i] != -1; i++) { 2698 channel_register_cleanup(s->x11_chanids[i], 2699 session_close_single_x11, 0); 2700 } 2701 2702 /* Set up a suitable value for the DISPLAY variable. */ 2703 if (gethostname(hostname, sizeof(hostname)) < 0) 2704 fatal("gethostname: %.100s", strerror(errno)); 2705 /* 2706 * auth_display must be used as the displayname when the 2707 * authorization entry is added with xauth(1). This will be 2708 * different than the DISPLAY string for localhost displays. 2709 */ 2710 if (options.x11_use_localhost) { 2711 snprintf(display, sizeof display, "localhost:%u.%u", 2712 s->display_number, s->screen); 2713 snprintf(auth_display, sizeof auth_display, "unix:%u.%u", 2714 s->display_number, s->screen); 2715 s->display = xstrdup(display); 2716 s->auth_display = xstrdup(auth_display); 2717 } else { 2718#ifdef IPADDR_IN_DISPLAY 2719 struct hostent *he; 2720 struct in_addr my_addr; 2721 2722 he = gethostbyname(hostname); 2723 if (he == NULL) { 2724 error("Can't get IP address for X11 DISPLAY."); 2725 packet_send_debug("Can't get IP address for X11 DISPLAY."); 2726 return 0; 2727 } 2728 memcpy(&my_addr, he->h_addr_list[0], sizeof(struct in_addr)); 2729 snprintf(display, sizeof display, "%.50s:%u.%u", inet_ntoa(my_addr), 2730 s->display_number, s->screen); 2731#else 2732 snprintf(display, sizeof display, "%.400s:%u.%u", hostname, 2733 s->display_number, s->screen); 2734#endif 2735 s->display = xstrdup(display); 2736 s->auth_display = xstrdup(display); 2737 } 2738 2739 return 1; 2740} 2741 2742static void 2743do_authenticated2(Authctxt *authctxt) 2744{ 2745 server_loop2(authctxt); 2746} 2747 2748void 2749do_cleanup(Authctxt *authctxt) 2750{ 2751 static int called = 0; 2752 2753 debug("do_cleanup"); 2754 2755 /* no cleanup if we're in the child for login shell */ 2756 if (is_child) 2757 return; 2758 2759 /* avoid double cleanup */ 2760 if (called) 2761 return; 2762 called = 1; 2763 2764 if (authctxt == NULL) 2765 return; 2766 2767#ifdef USE_PAM 2768 if (options.use_pam) { 2769 sshpam_cleanup(); 2770 sshpam_thread_cleanup(); 2771 } 2772#endif 2773 2774 if (!authctxt->authenticated) 2775 return; 2776 2777#ifdef KRB5 2778 if (options.kerberos_ticket_cleanup && 2779 authctxt->krb5_ctx) 2780 krb5_cleanup_proc(authctxt); 2781#endif 2782 2783#ifdef GSSAPI 2784 if (compat20 && options.gss_cleanup_creds) 2785 ssh_gssapi_cleanup_creds(); 2786#endif 2787 2788 /* remove agent socket */ 2789 auth_sock_cleanup_proc(authctxt->pw); 2790 2791 /* 2792 * Cleanup ptys/utmp only if privsep is disabled, 2793 * or if running in monitor. 2794 */ 2795 if (!use_privsep || mm_is_monitor()) 2796 session_destroy_all(session_pty_cleanup2); 2797} 2798