session.c revision 1.12.4.1
1/* $NetBSD: session.c,v 1.12.4.1 2015/04/30 06:07:30 riz Exp $ */ 2/* $OpenBSD: session.c,v 1.277 2015/01/16 06:40:12 deraadt Exp $ */ 3/* 4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 5 * All rights reserved 6 * 7 * As far as I am concerned, the code I have written for this software 8 * can be used freely for any purpose. Any derived versions of this 9 * software must be clearly marked as such, and if the derived work is 10 * incompatible with the protocol description in the RFC file, it must be 11 * called by a name other than "ssh" or "Secure Shell". 12 * 13 * SSH2 support by Markus Friedl. 14 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 15 * 16 * Redistribution and use in source and binary forms, with or without 17 * modification, are permitted provided that the following conditions 18 * are met: 19 * 1. Redistributions of source code must retain the above copyright 20 * notice, this list of conditions and the following disclaimer. 21 * 2. Redistributions in binary form must reproduce the above copyright 22 * notice, this list of conditions and the following disclaimer in the 23 * documentation and/or other materials provided with the distribution. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 26 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 27 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 28 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 29 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 30 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 31 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 32 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 33 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 34 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 35 */ 36 37#include "includes.h" 38__RCSID("$NetBSD: session.c,v 1.12.4.1 2015/04/30 06:07:30 riz Exp $"); 39#include <sys/types.h> 40#include <sys/wait.h> 41#include <sys/un.h> 42#include <sys/stat.h> 43#include <sys/socket.h> 44#include <sys/queue.h> 45 46#include <errno.h> 47#include <fcntl.h> 48#include <grp.h> 49#include <login_cap.h> 50#include <netdb.h> 51#include <paths.h> 52#include <pwd.h> 53#include <signal.h> 54#include <stdio.h> 55#include <stdlib.h> 56#include <string.h> 57#include <unistd.h> 58#include <limits.h> 59 60#include "xmalloc.h" 61#include "ssh.h" 62#include "ssh1.h" 63#include "ssh2.h" 64#include "sshpty.h" 65#include "packet.h" 66#include "buffer.h" 67#include "match.h" 68#include "uidswap.h" 69#include "compat.h" 70#include "channels.h" 71#include "key.h" 72#include "cipher.h" 73#include "kex.h" 74#include "hostfile.h" 75#include "auth.h" 76#include "auth-options.h" 77#include "authfd.h" 78#include "pathnames.h" 79#include "log.h" 80#include "misc.h" 81#include "servconf.h" 82#include "sshlogin.h" 83#include "serverloop.h" 84#include "canohost.h" 85#include "session.h" 86#ifdef GSSAPI 87#include "ssh-gss.h" 88#endif 89#include "monitor_wrap.h" 90#include "sftp.h" 91 92#ifdef KRB5 93#include <krb5/kafs.h> 94#endif 95 96#define IS_INTERNAL_SFTP(c) \ 97 (!strncmp(c, INTERNAL_SFTP_NAME, sizeof(INTERNAL_SFTP_NAME) - 1) && \ 98 (c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\0' || \ 99 c[sizeof(INTERNAL_SFTP_NAME) - 1] == ' ' || \ 100 c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\t')) 101 102/* func */ 103 104Session *session_new(void); 105void session_set_fds(Session *, int, int, int, int, int); 106void session_pty_cleanup(Session *); 107void session_proctitle(Session *); 108int session_setup_x11fwd(Session *); 109int do_exec_pty(Session *, const char *); 110int do_exec_no_pty(Session *, const char *); 111int do_exec(Session *, const char *); 112void do_login(Session *, const char *); 113__dead void do_child(Session *, const char *); 114void do_motd(void); 115int check_quietlogin(Session *, const char *); 116 117static void do_authenticated1(Authctxt *); 118static void do_authenticated2(Authctxt *); 119 120static int session_pty_req(Session *); 121 122/* import */ 123extern ServerOptions options; 124extern char *__progname; 125extern int log_stderr; 126extern int debug_flag; 127extern u_int utmp_len; 128extern int startup_pipe; 129extern void destroy_sensitive_data(void); 130extern Buffer loginmsg; 131 132/* original command from peer. */ 133const char *original_command = NULL; 134 135/* data */ 136static int sessions_first_unused = -1; 137static int sessions_nalloc = 0; 138static Session *sessions = NULL; 139 140#define SUBSYSTEM_NONE 0 141#define SUBSYSTEM_EXT 1 142#define SUBSYSTEM_INT_SFTP 2 143#define SUBSYSTEM_INT_SFTP_ERROR 3 144 145#ifdef HAVE_LOGIN_CAP 146login_cap_t *lc; 147#endif 148 149static int is_child = 0; 150 151/* Name and directory of socket for authentication agent forwarding. */ 152static char *auth_sock_name = NULL; 153static char *auth_sock_dir = NULL; 154 155/* removes the agent forwarding socket */ 156 157static void 158auth_sock_cleanup_proc(struct passwd *pw) 159{ 160 if (auth_sock_name != NULL) { 161 temporarily_use_uid(pw); 162 unlink(auth_sock_name); 163 rmdir(auth_sock_dir); 164 auth_sock_name = NULL; 165 restore_uid(); 166 } 167} 168 169static int 170auth_input_request_forwarding(struct passwd * pw) 171{ 172 Channel *nc; 173 int sock = -1; 174 175 if (auth_sock_name != NULL) { 176 error("authentication forwarding requested twice."); 177 return 0; 178 } 179 180 /* Temporarily drop privileged uid for mkdir/bind. */ 181 temporarily_use_uid(pw); 182 183 /* Allocate a buffer for the socket name, and format the name. */ 184 auth_sock_dir = xstrdup("/tmp/ssh-XXXXXXXXXX"); 185 186 /* Create private directory for socket */ 187 if (mkdtemp(auth_sock_dir) == NULL) { 188 packet_send_debug("Agent forwarding disabled: " 189 "mkdtemp() failed: %.100s", strerror(errno)); 190 restore_uid(); 191 free(auth_sock_dir); 192 auth_sock_dir = NULL; 193 goto authsock_err; 194 } 195 196 xasprintf(&auth_sock_name, "%s/agent.%ld", 197 auth_sock_dir, (long) getpid()); 198 199 /* Start a Unix listener on auth_sock_name. */ 200 sock = unix_listener(auth_sock_name, SSH_LISTEN_BACKLOG, 0); 201 202 /* Restore the privileged uid. */ 203 restore_uid(); 204 205 /* Check for socket/bind/listen failure. */ 206 if (sock < 0) 207 goto authsock_err; 208 209 /* Allocate a channel for the authentication agent socket. */ 210 /* this shouldn't matter if its hpn or not - cjr */ 211 nc = channel_new("auth socket", 212 SSH_CHANNEL_AUTH_SOCKET, sock, sock, -1, 213 CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 214 0, "auth socket", 1); 215 nc->path = xstrdup(auth_sock_name); 216 return 1; 217 218 authsock_err: 219 free(auth_sock_name); 220 if (auth_sock_dir != NULL) { 221 rmdir(auth_sock_dir); 222 free(auth_sock_dir); 223 } 224 if (sock != -1) 225 close(sock); 226 auth_sock_name = NULL; 227 auth_sock_dir = NULL; 228 return 0; 229} 230 231static void 232display_loginmsg(void) 233{ 234 if (buffer_len(&loginmsg) > 0) { 235 buffer_append(&loginmsg, "\0", 1); 236 printf("%s", (char *)buffer_ptr(&loginmsg)); 237 buffer_clear(&loginmsg); 238 } 239} 240 241void 242do_authenticated(Authctxt *authctxt) 243{ 244 setproctitle("%s", authctxt->pw->pw_name); 245 246 /* setup the channel layer */ 247 /* XXX - streamlocal? */ 248 if (no_port_forwarding_flag || 249 (options.allow_tcp_forwarding & FORWARD_LOCAL) == 0) 250 channel_disable_adm_local_opens(); 251 else 252 channel_permit_all_opens(); 253 254 auth_debug_send(); 255 256 if (compat20) 257 do_authenticated2(authctxt); 258 else 259 do_authenticated1(authctxt); 260 261 do_cleanup(authctxt); 262} 263 264/* 265 * Prepares for an interactive session. This is called after the user has 266 * been successfully authenticated. During this message exchange, pseudo 267 * terminals are allocated, X11, TCP/IP, and authentication agent forwardings 268 * are requested, etc. 269 */ 270static void 271do_authenticated1(Authctxt *authctxt) 272{ 273 Session *s; 274 char *command; 275 int success, type, screen_flag; 276 int enable_compression_after_reply = 0; 277 u_int proto_len, data_len, dlen, compression_level = 0; 278 279 s = session_new(); 280 if (s == NULL) { 281 error("no more sessions"); 282 return; 283 } 284 s->authctxt = authctxt; 285 s->pw = authctxt->pw; 286 287 /* 288 * We stay in this loop until the client requests to execute a shell 289 * or a command. 290 */ 291 for (;;) { 292 success = 0; 293 294 /* Get a packet from the client. */ 295 type = packet_read(); 296 297 /* Process the packet. */ 298 switch (type) { 299 case SSH_CMSG_REQUEST_COMPRESSION: 300 compression_level = packet_get_int(); 301 packet_check_eom(); 302 if (compression_level < 1 || compression_level > 9) { 303 packet_send_debug("Received invalid compression level %d.", 304 compression_level); 305 break; 306 } 307 if (options.compression == COMP_NONE) { 308 debug2("compression disabled"); 309 break; 310 } 311 /* Enable compression after we have responded with SUCCESS. */ 312 enable_compression_after_reply = 1; 313 success = 1; 314 break; 315 316 case SSH_CMSG_REQUEST_PTY: 317 success = session_pty_req(s); 318 break; 319 320 case SSH_CMSG_X11_REQUEST_FORWARDING: 321 s->auth_proto = packet_get_string(&proto_len); 322 s->auth_data = packet_get_string(&data_len); 323 324 screen_flag = packet_get_protocol_flags() & 325 SSH_PROTOFLAG_SCREEN_NUMBER; 326 debug2("SSH_PROTOFLAG_SCREEN_NUMBER: %d", screen_flag); 327 328 if (packet_remaining() == 4) { 329 if (!screen_flag) 330 debug2("Buggy client: " 331 "X11 screen flag missing"); 332 s->screen = packet_get_int(); 333 } else { 334 s->screen = 0; 335 } 336 packet_check_eom(); 337 success = session_setup_x11fwd(s); 338 if (!success) { 339 free(s->auth_proto); 340 free(s->auth_data); 341 s->auth_proto = NULL; 342 s->auth_data = NULL; 343 } 344 break; 345 346 case SSH_CMSG_AGENT_REQUEST_FORWARDING: 347 if (!options.allow_agent_forwarding || 348 no_agent_forwarding_flag || compat13) { 349 debug("Authentication agent forwarding not permitted for this authentication."); 350 break; 351 } 352 debug("Received authentication agent forwarding request."); 353 success = auth_input_request_forwarding(s->pw); 354 break; 355 356 case SSH_CMSG_PORT_FORWARD_REQUEST: 357 if (no_port_forwarding_flag) { 358 debug("Port forwarding not permitted for this authentication."); 359 break; 360 } 361 if (!(options.allow_tcp_forwarding & FORWARD_REMOTE)) { 362 debug("Port forwarding not permitted."); 363 break; 364 } 365 debug("Received TCP/IP port forwarding request."); 366 if (channel_input_port_forward_request(s->pw->pw_uid == 0, 367 &options.fwd_opts) < 0) { 368 debug("Port forwarding failed."); 369 break; 370 } 371 success = 1; 372 break; 373 374 case SSH_CMSG_MAX_PACKET_SIZE: 375 if (packet_set_maxsize(packet_get_int()) > 0) 376 success = 1; 377 break; 378 379#if defined(AFS) || defined(KRB5) 380 case SSH_CMSG_HAVE_KERBEROS_TGT: 381 if (!options.kerberos_tgt_passing) { 382 verbose("Kerberos TGT passing disabled."); 383 } else { 384 char *kdata = packet_get_string(&dlen); 385 packet_check_eom(); 386 387 /* XXX - 0x41, see creds_to_radix version */ 388 if (kdata[0] != 0x41) { 389#ifdef KRB5 390 krb5_data tgt; 391 tgt.data = kdata; 392 tgt.length = dlen; 393 394 if (auth_krb5_tgt(s->authctxt, &tgt)) 395 success = 1; 396 else 397 verbose("Kerberos v5 TGT refused for %.100s", s->authctxt->user); 398#endif /* KRB5 */ 399 } else { 400#ifdef AFS 401 if (auth_krb4_tgt(s->authctxt, kdata)) 402 success = 1; 403 else 404 verbose("Kerberos v4 TGT refused for %.100s", s->authctxt->user); 405#endif /* AFS */ 406 } 407 free(kdata); 408 } 409 break; 410#endif /* AFS || KRB5 */ 411 412#ifdef AFS 413 case SSH_CMSG_HAVE_AFS_TOKEN: 414 if (!options.afs_token_passing || !k_hasafs()) { 415 verbose("AFS token passing disabled."); 416 } else { 417 /* Accept AFS token. */ 418 char *token = packet_get_string(&dlen); 419 packet_check_eom(); 420 421 if (auth_afs_token(s->authctxt, token)) 422 success = 1; 423 else 424 verbose("AFS token refused for %.100s", 425 s->authctxt->user); 426 free(token); 427 } 428 break; 429#endif /* AFS */ 430 431 case SSH_CMSG_EXEC_SHELL: 432 case SSH_CMSG_EXEC_CMD: 433 if (type == SSH_CMSG_EXEC_CMD) { 434 command = packet_get_string(&dlen); 435 debug("Exec command '%.500s'", command); 436 if (do_exec(s, command) != 0) 437 packet_disconnect( 438 "command execution failed"); 439 free(command); 440 } else { 441 if (do_exec(s, NULL) != 0) 442 packet_disconnect( 443 "shell execution failed"); 444 } 445 packet_check_eom(); 446 session_close(s); 447 return; 448 449 default: 450 /* 451 * Any unknown messages in this phase are ignored, 452 * and a failure message is returned. 453 */ 454 logit("Unknown packet type received after authentication: %d", type); 455 } 456 packet_start(success ? SSH_SMSG_SUCCESS : SSH_SMSG_FAILURE); 457 packet_send(); 458 packet_write_wait(); 459 460 /* Enable compression now that we have replied if appropriate. */ 461 if (enable_compression_after_reply) { 462 enable_compression_after_reply = 0; 463 packet_start_compression(compression_level); 464 } 465 } 466} 467 468#define USE_PIPES 1 469/* 470 * This is called to fork and execute a command when we have no tty. This 471 * will call do_child from the child, and server_loop from the parent after 472 * setting up file descriptors and such. 473 */ 474int 475do_exec_no_pty(Session *s, const char *command) 476{ 477 pid_t pid; 478#ifdef USE_PIPES 479 int pin[2], pout[2], perr[2]; 480 481 if (s == NULL) 482 fatal("do_exec_no_pty: no session"); 483 484 /* Allocate pipes for communicating with the program. */ 485 if (pipe(pin) < 0) { 486 error("%s: pipe in: %.100s", __func__, strerror(errno)); 487 return -1; 488 } 489 if (pipe(pout) < 0) { 490 error("%s: pipe out: %.100s", __func__, strerror(errno)); 491 close(pin[0]); 492 close(pin[1]); 493 return -1; 494 } 495 if (pipe(perr) < 0) { 496 error("%s: pipe err: %.100s", __func__, 497 strerror(errno)); 498 close(pin[0]); 499 close(pin[1]); 500 close(pout[0]); 501 close(pout[1]); 502 return -1; 503 } 504#else 505 int inout[2], err[2]; 506 507 if (s == NULL) 508 fatal("do_exec_no_pty: no session"); 509 510 /* Uses socket pairs to communicate with the program. */ 511 if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) < 0) { 512 error("%s: socketpair #1: %.100s", __func__, strerror(errno)); 513 return -1; 514 } 515 if (socketpair(AF_UNIX, SOCK_STREAM, 0, err) < 0) { 516 error("%s: socketpair #2: %.100s", __func__, 517 strerror(errno)); 518 close(inout[0]); 519 close(inout[1]); 520 return -1; 521 } 522#endif 523 524 session_proctitle(s); 525 526#ifdef notdef 527#if defined(USE_PAM) 528 if (options.use_pam && !use_privsep) 529 do_pam_setcred(1); 530#endif /* USE_PAM */ 531#endif 532 533 /* Fork the child. */ 534 switch ((pid = fork())) { 535 case -1: 536 error("%s: fork: %.100s", __func__, strerror(errno)); 537#ifdef USE_PIPES 538 close(pin[0]); 539 close(pin[1]); 540 close(pout[0]); 541 close(pout[1]); 542 close(perr[0]); 543 close(perr[1]); 544#else 545 close(inout[0]); 546 close(inout[1]); 547 close(err[0]); 548 close(err[1]); 549#endif 550 return -1; 551 case 0: 552 is_child = 1; 553 554 /* Child. Reinitialize the log since the pid has changed. */ 555 log_init(__progname, options.log_level, 556 options.log_facility, log_stderr); 557 558 /* 559 * Create a new session and process group since the 4.4BSD 560 * setlogin() affects the entire process group. 561 */ 562 if (setsid() < 0) 563 error("setsid failed: %.100s", strerror(errno)); 564 565#ifdef USE_PIPES 566 /* 567 * Redirect stdin. We close the parent side of the socket 568 * pair, and make the child side the standard input. 569 */ 570 close(pin[1]); 571 if (dup2(pin[0], 0) < 0) 572 perror("dup2 stdin"); 573 close(pin[0]); 574 575 /* Redirect stdout. */ 576 close(pout[0]); 577 if (dup2(pout[1], 1) < 0) 578 perror("dup2 stdout"); 579 close(pout[1]); 580 581 /* Redirect stderr. */ 582 close(perr[0]); 583 if (dup2(perr[1], 2) < 0) 584 perror("dup2 stderr"); 585 close(perr[1]); 586#else 587 /* 588 * Redirect stdin, stdout, and stderr. Stdin and stdout will 589 * use the same socket, as some programs (particularly rdist) 590 * seem to depend on it. 591 */ 592 close(inout[1]); 593 close(err[1]); 594 if (dup2(inout[0], 0) < 0) /* stdin */ 595 perror("dup2 stdin"); 596 if (dup2(inout[0], 1) < 0) /* stdout (same as stdin) */ 597 perror("dup2 stdout"); 598 close(inout[0]); 599 if (dup2(err[0], 2) < 0) /* stderr */ 600 perror("dup2 stderr"); 601 close(err[0]); 602#endif 603 604 /* Do processing for the child (exec command etc). */ 605 do_child(s, command); 606 /* NOTREACHED */ 607 default: 608 break; 609 } 610 611 s->pid = pid; 612 /* Set interactive/non-interactive mode. */ 613 packet_set_interactive(s->display != NULL, 614 options.ip_qos_interactive, options.ip_qos_bulk); 615 616#ifdef USE_PIPES 617 /* We are the parent. Close the child sides of the pipes. */ 618 close(pin[0]); 619 close(pout[1]); 620 close(perr[1]); 621 622 if (compat20) { 623 session_set_fds(s, pin[1], pout[0], perr[0], 624 s->is_subsystem, 0); 625 } else { 626 /* Enter the interactive session. */ 627 server_loop(pid, pin[1], pout[0], perr[0]); 628 /* server_loop has closed pin[1], pout[0], and perr[0]. */ 629 } 630#else 631 /* We are the parent. Close the child sides of the socket pairs. */ 632 close(inout[0]); 633 close(err[0]); 634 635 /* 636 * Enter the interactive session. Note: server_loop must be able to 637 * handle the case that fdin and fdout are the same. 638 */ 639 if (compat20) { 640 session_set_fds(s, inout[1], inout[1], err[1], 641 s->is_subsystem, 0); 642 } else { 643 server_loop(pid, inout[1], inout[1], err[1]); 644 /* server_loop has closed inout[1] and err[1]. */ 645 } 646#endif 647 return 0; 648} 649 650/* 651 * This is called to fork and execute a command when we have a tty. This 652 * will call do_child from the child, and server_loop from the parent after 653 * setting up file descriptors, controlling tty, updating wtmp, utmp, 654 * lastlog, and other such operations. 655 */ 656int 657do_exec_pty(Session *s, const char *command) 658{ 659 int fdout, ptyfd, ttyfd, ptymaster; 660 pid_t pid; 661 662 if (s == NULL) 663 fatal("do_exec_pty: no session"); 664 ptyfd = s->ptyfd; 665 ttyfd = s->ttyfd; 666 667#if defined(USE_PAM) 668 if (options.use_pam) { 669 do_pam_set_tty(s->tty); 670 if (!use_privsep) 671 do_pam_setcred(1); 672 } 673#endif 674 675 /* 676 * Create another descriptor of the pty master side for use as the 677 * standard input. We could use the original descriptor, but this 678 * simplifies code in server_loop. The descriptor is bidirectional. 679 * Do this before forking (and cleanup in the child) so as to 680 * detect and gracefully fail out-of-fd conditions. 681 */ 682 if ((fdout = dup(ptyfd)) < 0) { 683 error("%s: dup #1: %s", __func__, strerror(errno)); 684 close(ttyfd); 685 close(ptyfd); 686 return -1; 687 } 688 /* we keep a reference to the pty master */ 689 if ((ptymaster = dup(ptyfd)) < 0) { 690 error("%s: dup #2: %s", __func__, strerror(errno)); 691 close(ttyfd); 692 close(ptyfd); 693 close(fdout); 694 return -1; 695 } 696 697 /* Fork the child. */ 698 switch ((pid = fork())) { 699 case -1: 700 error("%s: fork: %.100s", __func__, strerror(errno)); 701 close(fdout); 702 close(ptymaster); 703 close(ttyfd); 704 close(ptyfd); 705 return -1; 706 case 0: 707 is_child = 1; 708 709 close(fdout); 710 close(ptymaster); 711 712 /* Child. Reinitialize the log because the pid has changed. */ 713 log_init(__progname, options.log_level, 714 options.log_facility, log_stderr); 715 /* Close the master side of the pseudo tty. */ 716 close(ptyfd); 717 718 /* Make the pseudo tty our controlling tty. */ 719 pty_make_controlling_tty(&ttyfd, s->tty); 720 721 /* Redirect stdin/stdout/stderr from the pseudo tty. */ 722 if (dup2(ttyfd, 0) < 0) 723 error("dup2 stdin: %s", strerror(errno)); 724 if (dup2(ttyfd, 1) < 0) 725 error("dup2 stdout: %s", strerror(errno)); 726 if (dup2(ttyfd, 2) < 0) 727 error("dup2 stderr: %s", strerror(errno)); 728 729 /* Close the extra descriptor for the pseudo tty. */ 730 close(ttyfd); 731 732 /* record login, etc. similar to login(1) */ 733 if (!(options.use_login && command == NULL)) 734 do_login(s, command); 735 736 /* 737 * Do common processing for the child, such as execing 738 * the command. 739 */ 740 do_child(s, command); 741 /* NOTREACHED */ 742 default: 743 break; 744 } 745 s->pid = pid; 746 747 /* Parent. Close the slave side of the pseudo tty. */ 748 close(ttyfd); 749 750 /* Enter interactive session. */ 751 s->ptymaster = ptymaster; 752 packet_set_interactive(1, 753 options.ip_qos_interactive, options.ip_qos_bulk); 754 if (compat20) { 755 session_set_fds(s, ptyfd, fdout, -1, 1, 1); 756 } else { 757 server_loop(pid, ptyfd, fdout, -1); 758 /* server_loop _has_ closed ptyfd and fdout. */ 759 } 760 return 0; 761} 762 763/* 764 * This is called to fork and execute a command. If another command is 765 * to be forced, execute that instead. 766 */ 767int 768do_exec(Session *s, const char *command) 769{ 770 int ret; 771 const char *forced = NULL; 772 char session_type[1024], *tty = NULL; 773 774 if (options.adm_forced_command) { 775 original_command = command; 776 command = options.adm_forced_command; 777 forced = "(config)"; 778 } else if (forced_command) { 779 original_command = command; 780 command = forced_command; 781 forced = "(key-option)"; 782 } 783 if (forced != NULL) { 784 if (IS_INTERNAL_SFTP(command)) { 785 s->is_subsystem = s->is_subsystem ? 786 SUBSYSTEM_INT_SFTP : SUBSYSTEM_INT_SFTP_ERROR; 787 } else if (s->is_subsystem) 788 s->is_subsystem = SUBSYSTEM_EXT; 789 snprintf(session_type, sizeof(session_type), 790 "forced-command %s '%.900s'", forced, command); 791 } else if (s->is_subsystem) { 792 snprintf(session_type, sizeof(session_type), 793 "subsystem '%.900s'", s->subsys); 794 } else if (command == NULL) { 795 snprintf(session_type, sizeof(session_type), "shell"); 796 } else { 797 /* NB. we don't log unforced commands to preserve privacy */ 798 snprintf(session_type, sizeof(session_type), "command"); 799 } 800 801 if (s->ttyfd != -1) { 802 tty = s->tty; 803 if (strncmp(tty, "/dev/", 5) == 0) 804 tty += 5; 805 } 806 807 verbose("Starting session: %s%s%s for %s from %.200s port %d", 808 session_type, 809 tty == NULL ? "" : " on ", 810 tty == NULL ? "" : tty, 811 s->pw->pw_name, 812 get_remote_ipaddr(), 813 get_remote_port()); 814 815#ifdef GSSAPI 816 if (options.gss_authentication) { 817 temporarily_use_uid(s->pw); 818 ssh_gssapi_storecreds(); 819 restore_uid(); 820 } 821#endif 822 if (s->ttyfd != -1) 823 ret = do_exec_pty(s, command); 824 else 825 ret = do_exec_no_pty(s, command); 826 827 original_command = NULL; 828 829 /* 830 * Clear loginmsg: it's the child's responsibility to display 831 * it to the user, otherwise multiple sessions may accumulate 832 * multiple copies of the login messages. 833 */ 834 buffer_clear(&loginmsg); 835 836 return ret; 837} 838 839 840/* administrative, login(1)-like work */ 841void 842do_login(Session *s, const char *command) 843{ 844 socklen_t fromlen; 845 struct sockaddr_storage from; 846 struct passwd * pw = s->pw; 847 pid_t pid = getpid(); 848 849 /* 850 * Get IP address of client. If the connection is not a socket, let 851 * the address be 0.0.0.0. 852 */ 853 memset(&from, 0, sizeof(from)); 854 fromlen = sizeof(from); 855 if (packet_connection_is_on_socket()) { 856 if (getpeername(packet_get_connection_in(), 857 (struct sockaddr *)&from, &fromlen) < 0) { 858 debug("getpeername: %.100s", strerror(errno)); 859 cleanup_exit(255); 860 } 861 } 862 863 /* Record that there was a login on that tty from the remote host. */ 864 if (!use_privsep) 865 record_login(pid, s->tty, pw->pw_name, pw->pw_uid, 866 get_remote_name_or_ip(utmp_len, 867 options.use_dns), 868 (struct sockaddr *)&from, fromlen); 869 870#ifdef USE_PAM 871 /* 872 * If password change is needed, do it now. 873 * This needs to occur before the ~/.hushlogin check. 874 */ 875 if (options.use_pam && !use_privsep && s->authctxt->force_pwchange) { 876 display_loginmsg(); 877 do_pam_chauthtok(); 878 s->authctxt->force_pwchange = 0; 879 /* XXX - signal [net] parent to enable forwardings */ 880 } 881#endif 882 883 if (check_quietlogin(s, command)) 884 return; 885 886 display_loginmsg(); 887 888 do_motd(); 889} 890 891/* 892 * Display the message of the day. 893 */ 894void 895do_motd(void) 896{ 897 FILE *f; 898 char buf[256]; 899 900 if (options.print_motd) { 901#ifdef HAVE_LOGIN_CAP 902 f = fopen(login_getcapstr(lc, "welcome", __UNCONST("/etc/motd"), 903 __UNCONST("/etc/motd")), "r"); 904#else 905 f = fopen("/etc/motd", "r"); 906#endif 907 if (f) { 908 while (fgets(buf, sizeof(buf), f)) 909 fputs(buf, stdout); 910 fclose(f); 911 } 912 } 913} 914 915 916/* 917 * Check for quiet login, either .hushlogin or command given. 918 */ 919int 920check_quietlogin(Session *s, const char *command) 921{ 922 char buf[256]; 923 struct passwd *pw = s->pw; 924 struct stat st; 925 926 /* Return 1 if .hushlogin exists or a command given. */ 927 if (command != NULL) 928 return 1; 929 snprintf(buf, sizeof(buf), "%.200s/.hushlogin", pw->pw_dir); 930#ifdef HAVE_LOGIN_CAP 931 if (login_getcapbool(lc, "hushlogin", 0) || stat(buf, &st) >= 0) 932 return 1; 933#else 934 if (stat(buf, &st) >= 0) 935 return 1; 936#endif 937 return 0; 938} 939 940/* 941 * Sets the value of the given variable in the environment. If the variable 942 * already exists, its value is overridden. 943 */ 944void 945child_set_env(char ***envp, u_int *envsizep, const char *name, 946 const char *value) 947{ 948 char **env; 949 u_int envsize; 950 u_int i, namelen; 951 952 if (strchr(name, '=') != NULL) { 953 error("Invalid environment variable \"%.100s\"", name); 954 return; 955 } 956 957 /* 958 * Find the slot where the value should be stored. If the variable 959 * already exists, we reuse the slot; otherwise we append a new slot 960 * at the end of the array, expanding if necessary. 961 */ 962 env = *envp; 963 namelen = strlen(name); 964 for (i = 0; env[i]; i++) 965 if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=') 966 break; 967 if (env[i]) { 968 /* Reuse the slot. */ 969 free(env[i]); 970 } else { 971 /* New variable. Expand if necessary. */ 972 envsize = *envsizep; 973 if (i >= envsize - 1) { 974 if (envsize >= 1000) 975 fatal("child_set_env: too many env vars"); 976 envsize += 50; 977 env = (*envp) = xrealloc(env, envsize, sizeof(char *)); 978 *envsizep = envsize; 979 } 980 /* Need to set the NULL pointer at end of array beyond the new slot. */ 981 env[i + 1] = NULL; 982 } 983 984 /* Allocate space and format the variable in the appropriate slot. */ 985 env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1); 986 snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value); 987} 988 989#ifdef HAVE_LOGIN_CAP 990/* 991 * Sets any environment variables specified in login.conf. 992 * Taken from: 993 * NetBSD: login_cap.c,v 1.11 2001/07/22 13:34:01 wiz Exp 994 * Modified to use child_set_env instead of setenv. 995 */ 996static void 997lc_setuserenv(char ***env, u_int *envsize, login_cap_t *lcp) 998{ 999 const char *stop = ", \t"; 1000 int i, count; 1001 char *ptr; 1002 char **res; 1003 char *str = login_getcapstr(lcp, "setenv", NULL, NULL); 1004 1005 if (str == NULL || *str == '\0') 1006 return; 1007 1008 /* count the sub-strings */ 1009 for (i = 1, ptr = str; *ptr; i++) { 1010 ptr += strcspn(ptr, stop); 1011 if (*ptr) 1012 ptr++; 1013 } 1014 1015 /* allocate ptr array and string */ 1016 count = i; 1017 res = malloc(count * sizeof(char *) + strlen(str) + 1); 1018 1019 if (!res) 1020 return; 1021 1022 ptr = (char *)res + count * sizeof(char *); 1023 strcpy(ptr, str); 1024 1025 /* split string */ 1026 for (i = 0; *ptr && i < count; i++) { 1027 res[i] = ptr; 1028 ptr += strcspn(ptr, stop); 1029 if (*ptr) 1030 *ptr++ = '\0'; 1031 } 1032 1033 res[i] = NULL; 1034 1035 for (i = 0; i < count && res[i]; i++) { 1036 if (*res[i] != '\0') { 1037 if ((ptr = strchr(res[i], '=')) != NULL) 1038 *ptr++ = '\0'; 1039 else 1040 ptr = __UNCONST(""); 1041 child_set_env(env, envsize, res[i], ptr); 1042 } 1043 } 1044 1045 free(res); 1046 return; 1047} 1048#endif 1049 1050/* 1051 * Reads environment variables from the given file and adds/overrides them 1052 * into the environment. If the file does not exist, this does nothing. 1053 * Otherwise, it must consist of empty lines, comments (line starts with '#') 1054 * and assignments of the form name=value. No other forms are allowed. 1055 */ 1056static void 1057read_environment_file(char ***env, u_int *envsize, 1058 const char *filename) 1059{ 1060 FILE *f; 1061 char buf[4096]; 1062 char *cp, *value; 1063 u_int lineno = 0; 1064 1065 f = fopen(filename, "r"); 1066 if (!f) 1067 return; 1068 1069 while (fgets(buf, sizeof(buf), f)) { 1070 if (++lineno > 1000) 1071 fatal("Too many lines in environment file %s", filename); 1072 for (cp = buf; *cp == ' ' || *cp == '\t'; cp++) 1073 ; 1074 if (!*cp || *cp == '#' || *cp == '\n') 1075 continue; 1076 1077 cp[strcspn(cp, "\n")] = '\0'; 1078 1079 value = strchr(cp, '='); 1080 if (value == NULL) { 1081 fprintf(stderr, "Bad line %u in %.100s\n", lineno, 1082 filename); 1083 continue; 1084 } 1085 /* 1086 * Replace the equals sign by nul, and advance value to 1087 * the value string. 1088 */ 1089 *value = '\0'; 1090 value++; 1091 child_set_env(env, envsize, cp, value); 1092 } 1093 fclose(f); 1094} 1095 1096#ifdef USE_PAM 1097void copy_environment(char **, char ***, u_int *); 1098void copy_environment(char **source, char ***env, u_int *envsize) 1099{ 1100 char *var_name, *var_val; 1101 int i; 1102 1103 if (source == NULL) 1104 return; 1105 1106 for (i = 0; source[i] != NULL; i++) { 1107 var_name = xstrdup(source[i]); 1108 if ((var_val = strstr(var_name, "=")) == NULL) { 1109 free(var_name); 1110 continue; 1111 } 1112 *var_val++ = '\0'; 1113 1114 debug3("Copy environment: %s=%s", var_name, var_val); 1115 child_set_env(env, envsize, var_name, var_val); 1116 1117 free(var_name); 1118 } 1119} 1120#endif 1121 1122static char ** 1123do_setup_env(Session *s, const char *shell) 1124{ 1125 char buf[256]; 1126 u_int i, envsize; 1127 char **env, *laddr; 1128 struct passwd *pw = s->pw; 1129 1130 /* Initialize the environment. */ 1131 envsize = 100; 1132 env = xcalloc(envsize, sizeof(char *)); 1133 env[0] = NULL; 1134 1135#ifdef GSSAPI 1136 /* Allow any GSSAPI methods that we've used to alter 1137 * the childs environment as they see fit 1138 */ 1139 ssh_gssapi_do_child(&env, &envsize); 1140#endif 1141 1142 if (!options.use_login) { 1143#ifdef HAVE_LOGIN_CAP 1144 lc_setuserenv(&env, &envsize, lc); 1145#endif 1146 /* Set basic environment. */ 1147 for (i = 0; i < s->num_env; i++) 1148 child_set_env(&env, &envsize, s->env[i].name, 1149 s->env[i].val); 1150 1151 child_set_env(&env, &envsize, "USER", pw->pw_name); 1152 child_set_env(&env, &envsize, "LOGNAME", pw->pw_name); 1153 child_set_env(&env, &envsize, "HOME", pw->pw_dir); 1154#ifdef HAVE_LOGIN_CAP 1155 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETPATH) < 0) 1156 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); 1157 else 1158 child_set_env(&env, &envsize, "PATH", getenv("PATH")); 1159#else 1160 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); 1161#endif 1162 1163 snprintf(buf, sizeof buf, "%.200s/%.50s", 1164 _PATH_MAILDIR, pw->pw_name); 1165 child_set_env(&env, &envsize, "MAIL", buf); 1166 1167 /* Normal systems set SHELL by default. */ 1168 child_set_env(&env, &envsize, "SHELL", shell); 1169 } 1170 if (getenv("TZ")) 1171 child_set_env(&env, &envsize, "TZ", getenv("TZ")); 1172 1173 /* Set custom environment options from RSA authentication. */ 1174 if (!options.use_login) { 1175 while (custom_environment) { 1176 struct envstring *ce = custom_environment; 1177 char *str = ce->s; 1178 1179 for (i = 0; str[i] != '=' && str[i]; i++) 1180 ; 1181 if (str[i] == '=') { 1182 str[i] = 0; 1183 child_set_env(&env, &envsize, str, str + i + 1); 1184 } 1185 custom_environment = ce->next; 1186 free(ce->s); 1187 free(ce); 1188 } 1189 } 1190 1191 /* SSH_CLIENT deprecated */ 1192 snprintf(buf, sizeof buf, "%.50s %d %d", 1193 get_remote_ipaddr(), get_remote_port(), get_local_port()); 1194 child_set_env(&env, &envsize, "SSH_CLIENT", buf); 1195 1196 laddr = get_local_ipaddr(packet_get_connection_in()); 1197 snprintf(buf, sizeof buf, "%.50s %d %.50s %d", 1198 get_remote_ipaddr(), get_remote_port(), laddr, get_local_port()); 1199 free(laddr); 1200 child_set_env(&env, &envsize, "SSH_CONNECTION", buf); 1201 1202 if (s->ttyfd != -1) 1203 child_set_env(&env, &envsize, "SSH_TTY", s->tty); 1204 if (s->term) 1205 child_set_env(&env, &envsize, "TERM", s->term); 1206 if (s->display) 1207 child_set_env(&env, &envsize, "DISPLAY", s->display); 1208 if (original_command) 1209 child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND", 1210 original_command); 1211#ifdef KRB4 1212 if (s->authctxt->krb4_ticket_file) 1213 child_set_env(&env, &envsize, "KRBTKFILE", 1214 s->authctxt->krb4_ticket_file); 1215#endif 1216#ifdef KRB5 1217 if (s->authctxt->krb5_ticket_file) 1218 child_set_env(&env, &envsize, "KRB5CCNAME", 1219 s->authctxt->krb5_ticket_file); 1220#endif 1221#ifdef USE_PAM 1222 /* 1223 * Pull in any environment variables that may have 1224 * been set by PAM. 1225 */ 1226 if (options.use_pam) { 1227 char **p; 1228 1229 p = fetch_pam_child_environment(); 1230 copy_environment(p, &env, &envsize); 1231 free_pam_environment(p); 1232 1233 p = fetch_pam_environment(); 1234 copy_environment(p, &env, &envsize); 1235 free_pam_environment(p); 1236 } 1237#endif /* USE_PAM */ 1238 1239 if (auth_sock_name != NULL) 1240 child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME, 1241 auth_sock_name); 1242 1243 /* read $HOME/.ssh/environment. */ 1244 if (options.permit_user_env && !options.use_login) { 1245 snprintf(buf, sizeof buf, "%.200s/.ssh/environment", 1246 pw->pw_dir); 1247 read_environment_file(&env, &envsize, buf); 1248 } 1249 if (debug_flag) { 1250 /* dump the environment */ 1251 fprintf(stderr, "Environment:\n"); 1252 for (i = 0; env[i]; i++) 1253 fprintf(stderr, " %.200s\n", env[i]); 1254 } 1255 return env; 1256} 1257 1258/* 1259 * Run $HOME/.ssh/rc, /etc/ssh/sshrc, or xauth (whichever is found 1260 * first in this order). 1261 */ 1262static void 1263do_rc_files(Session *s, const char *shell) 1264{ 1265 FILE *f = NULL; 1266 char cmd[1024]; 1267 int do_xauth; 1268 struct stat st; 1269 1270 do_xauth = 1271 s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL; 1272 1273 /* ignore _PATH_SSH_USER_RC for subsystems and admin forced commands */ 1274 if (!s->is_subsystem && options.adm_forced_command == NULL && 1275 !no_user_rc && options.permit_user_rc && 1276 stat(_PATH_SSH_USER_RC, &st) >= 0) { 1277 snprintf(cmd, sizeof cmd, "%s -c '%s %s'", 1278 shell, _PATH_BSHELL, _PATH_SSH_USER_RC); 1279 if (debug_flag) 1280 fprintf(stderr, "Running %s\n", cmd); 1281 f = popen(cmd, "w"); 1282 if (f) { 1283 if (do_xauth) 1284 fprintf(f, "%s %s\n", s->auth_proto, 1285 s->auth_data); 1286 pclose(f); 1287 } else 1288 fprintf(stderr, "Could not run %s\n", 1289 _PATH_SSH_USER_RC); 1290 } else if (stat(_PATH_SSH_SYSTEM_RC, &st) >= 0) { 1291 if (debug_flag) 1292 fprintf(stderr, "Running %s %s\n", _PATH_BSHELL, 1293 _PATH_SSH_SYSTEM_RC); 1294 f = popen(_PATH_BSHELL " " _PATH_SSH_SYSTEM_RC, "w"); 1295 if (f) { 1296 if (do_xauth) 1297 fprintf(f, "%s %s\n", s->auth_proto, 1298 s->auth_data); 1299 pclose(f); 1300 } else 1301 fprintf(stderr, "Could not run %s\n", 1302 _PATH_SSH_SYSTEM_RC); 1303 } else if (do_xauth && options.xauth_location != NULL) { 1304 /* Add authority data to .Xauthority if appropriate. */ 1305 if (debug_flag) { 1306 fprintf(stderr, 1307 "Running %.500s remove %.100s\n", 1308 options.xauth_location, s->auth_display); 1309 fprintf(stderr, 1310 "%.500s add %.100s %.100s %.100s\n", 1311 options.xauth_location, s->auth_display, 1312 s->auth_proto, s->auth_data); 1313 } 1314 snprintf(cmd, sizeof cmd, "%s -q -", 1315 options.xauth_location); 1316 f = popen(cmd, "w"); 1317 if (f) { 1318 fprintf(f, "remove %s\n", 1319 s->auth_display); 1320 fprintf(f, "add %s %s %s\n", 1321 s->auth_display, s->auth_proto, 1322 s->auth_data); 1323 pclose(f); 1324 } else { 1325 fprintf(stderr, "Could not run %s\n", 1326 cmd); 1327 } 1328 } 1329} 1330 1331static void 1332do_nologin(struct passwd *pw) 1333{ 1334 FILE *f = NULL; 1335 char buf[1024], *nl, *def_nl = __UNCONST(_PATH_NOLOGIN); 1336 struct stat sb; 1337 1338#ifdef HAVE_LOGIN_CAP 1339 if (login_getcapbool(lc, "ignorenologin", 0) || pw->pw_uid == 0) 1340 return; 1341 nl = login_getcapstr(lc, "nologin", def_nl, def_nl); 1342 1343 if (stat(nl, &sb) == -1) { 1344 if (nl != def_nl) 1345 free(nl); 1346 return; 1347 } 1348#else 1349 if (pw->pw_uid) 1350 nl = def_nl; 1351#endif 1352 /* /etc/nologin exists. Print its contents if we can and exit. */ 1353 logit("User %.100s not allowed because %s exists", pw->pw_name, nl); 1354 if ((f = fopen(nl, "r")) != NULL) { 1355 while (fgets(buf, sizeof(buf), f)) 1356 fputs(buf, stderr); 1357 fclose(f); 1358 } 1359 exit(254); 1360} 1361 1362/* 1363 * Chroot into a directory after checking it for safety: all path components 1364 * must be root-owned directories with strict permissions. 1365 */ 1366static void 1367safely_chroot(const char *path, uid_t uid) 1368{ 1369 const char *cp; 1370 char component[PATH_MAX]; 1371 struct stat st; 1372 1373 if (*path != '/') 1374 fatal("chroot path does not begin at root"); 1375 if (strlen(path) >= sizeof(component)) 1376 fatal("chroot path too long"); 1377 1378 /* 1379 * Descend the path, checking that each component is a 1380 * root-owned directory with strict permissions. 1381 */ 1382 for (cp = path; cp != NULL;) { 1383 if ((cp = strchr(cp, '/')) == NULL) 1384 strlcpy(component, path, sizeof(component)); 1385 else { 1386 cp++; 1387 memcpy(component, path, cp - path); 1388 component[cp - path] = '\0'; 1389 } 1390 1391 debug3("%s: checking '%s'", __func__, component); 1392 1393 if (stat(component, &st) != 0) 1394 fatal("%s: stat(\"%s\"): %s", __func__, 1395 component, strerror(errno)); 1396 if (st.st_uid != 0 || (st.st_mode & 022) != 0) 1397 fatal("bad ownership or modes for chroot " 1398 "directory %s\"%s\"", 1399 cp == NULL ? "" : "component ", component); 1400 if (!S_ISDIR(st.st_mode)) 1401 fatal("chroot path %s\"%s\" is not a directory", 1402 cp == NULL ? "" : "component ", component); 1403 1404 } 1405 1406 if (chdir(path) == -1) 1407 fatal("Unable to chdir to chroot path \"%s\": " 1408 "%s", path, strerror(errno)); 1409 if (chroot(path) == -1) 1410 fatal("chroot(\"%s\"): %s", path, strerror(errno)); 1411 if (chdir("/") == -1) 1412 fatal("%s: chdir(/) after chroot: %s", 1413 __func__, strerror(errno)); 1414 verbose("Changed root directory to \"%s\"", path); 1415} 1416 1417/* Set login name, uid, gid, and groups. */ 1418void 1419do_setusercontext(struct passwd *pw) 1420{ 1421 char *chroot_path, *tmp; 1422 1423 if (getuid() == 0 || geteuid() == 0) { 1424#ifdef HAVE_LOGIN_CAP 1425# ifdef USE_PAM 1426 if (options.use_pam) { 1427 do_pam_setcred(use_privsep); 1428 } 1429# endif /* USE_PAM */ 1430 /* Prepare groups */ 1431 if (setusercontext(lc, pw, pw->pw_uid, 1432 (LOGIN_SETALL & ~(LOGIN_SETPATH|LOGIN_SETUSER))) < 0) { 1433 perror("unable to set user context"); 1434 exit(1); 1435 } 1436#else 1437 1438 if (setlogin(pw->pw_name) < 0) 1439 error("setlogin failed: %s", strerror(errno)); 1440 if (setgid(pw->pw_gid) < 0) { 1441 perror("setgid"); 1442 exit(1); 1443 } 1444 /* Initialize the group list. */ 1445 if (initgroups(pw->pw_name, pw->pw_gid) < 0) { 1446 perror("initgroups"); 1447 exit(1); 1448 } 1449 endgrent(); 1450# ifdef USE_PAM 1451 /* 1452 * PAM credentials may take the form of supplementary groups. 1453 * These will have been wiped by the above initgroups() call. 1454 * Reestablish them here. 1455 */ 1456 if (options.use_pam) { 1457 do_pam_setcred(use_privsep); 1458 } 1459# endif /* USE_PAM */ 1460#endif 1461 if (options.chroot_directory != NULL && 1462 strcasecmp(options.chroot_directory, "none") != 0) { 1463 tmp = tilde_expand_filename(options.chroot_directory, 1464 pw->pw_uid); 1465 chroot_path = percent_expand(tmp, "h", pw->pw_dir, 1466 "u", pw->pw_name, (char *)NULL); 1467 safely_chroot(chroot_path, pw->pw_uid); 1468 free(tmp); 1469 free(chroot_path); 1470 /* Make sure we don't attempt to chroot again */ 1471 free(options.chroot_directory); 1472 options.chroot_directory = NULL; 1473 } 1474 1475#ifdef HAVE_LOGIN_CAP 1476 /* Set UID */ 1477 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUSER) < 0) { 1478 perror("unable to set user context (setuser)"); 1479 exit(1); 1480 } 1481#else 1482 /* Permanently switch to the desired uid. */ 1483 permanently_set_uid(pw); 1484#endif 1485 } else if (options.chroot_directory != NULL && 1486 strcasecmp(options.chroot_directory, "none") != 0) { 1487 fatal("server lacks privileges to chroot to ChrootDirectory"); 1488 } 1489 1490 if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) 1491 fatal("Failed to set uids to %u.", (u_int) pw->pw_uid); 1492} 1493 1494__dead static void 1495do_pwchange(Session *s) 1496{ 1497 fflush(NULL); 1498 fprintf(stderr, "WARNING: Your password has expired.\n"); 1499 if (s->ttyfd != -1) { 1500 fprintf(stderr, 1501 "You must change your password now and login again!\n"); 1502 execl(_PATH_PASSWD_PROG, "passwd", (char *)NULL); 1503 perror("passwd"); 1504 } else { 1505 fprintf(stderr, 1506 "Password change required but no TTY available.\n"); 1507 } 1508 exit(1); 1509} 1510 1511__dead static void 1512launch_login(struct passwd *pw, const char *hostname) 1513{ 1514 /* Launch login(1). */ 1515 1516 execl("/usr/bin/login", "login", "-h", hostname, 1517 "-p", "-f", "--", pw->pw_name, (char *)NULL); 1518 1519 /* Login couldn't be executed, die. */ 1520 1521 perror("login"); 1522 exit(1); 1523} 1524 1525static void 1526child_close_fds(void) 1527{ 1528 extern int auth_sock; 1529 1530 if (auth_sock != -1) { 1531 close(auth_sock); 1532 auth_sock = -1; 1533 } 1534 1535 if (packet_get_connection_in() == packet_get_connection_out()) 1536 close(packet_get_connection_in()); 1537 else { 1538 close(packet_get_connection_in()); 1539 close(packet_get_connection_out()); 1540 } 1541 /* 1542 * Close all descriptors related to channels. They will still remain 1543 * open in the parent. 1544 */ 1545 /* XXX better use close-on-exec? -markus */ 1546 channel_close_all(); 1547 1548 /* 1549 * Close any extra file descriptors. Note that there may still be 1550 * descriptors left by system functions. They will be closed later. 1551 */ 1552 endpwent(); 1553 1554 /* 1555 * Close any extra open file descriptors so that we don't have them 1556 * hanging around in clients. Note that we want to do this after 1557 * initgroups, because at least on Solaris 2.3 it leaves file 1558 * descriptors open. 1559 */ 1560 closefrom(STDERR_FILENO + 1); 1561} 1562 1563/* 1564 * Performs common processing for the child, such as setting up the 1565 * environment, closing extra file descriptors, setting the user and group 1566 * ids, and executing the command or shell. 1567 */ 1568#define ARGV_MAX 10 1569void 1570do_child(Session *s, const char *command) 1571{ 1572 extern char **environ; 1573 char **env; 1574 char *argv[ARGV_MAX]; 1575 const char *shell, *shell0, *hostname = NULL; 1576 struct passwd *pw = s->pw; 1577 int r = 0; 1578 1579 /* remove hostkey from the child's memory */ 1580 destroy_sensitive_data(); 1581 1582 /* Force a password change */ 1583 if (s->authctxt->force_pwchange) { 1584 do_setusercontext(pw); 1585 child_close_fds(); 1586 do_pwchange(s); 1587 } 1588 1589 /* login(1) is only called if we execute the login shell */ 1590 if (options.use_login && command != NULL) 1591 options.use_login = 0; 1592 1593 /* 1594 * Login(1) does this as well, and it needs uid 0 for the "-h" 1595 * switch, so we let login(1) to this for us. 1596 */ 1597 if (!options.use_login) { 1598 do_nologin(pw); 1599 do_setusercontext(pw); 1600 /* 1601 * PAM session modules in do_setusercontext may have 1602 * generated messages, so if this in an interactive 1603 * login then display them too. 1604 */ 1605 if (!check_quietlogin(s, command)) 1606 display_loginmsg(); 1607 } 1608#ifdef USE_PAM 1609 if (options.use_pam && !is_pam_session_open()) { 1610 debug3("PAM session not opened, exiting"); 1611 display_loginmsg(); 1612 exit(254); 1613 } 1614#endif 1615 1616 /* 1617 * Get the shell from the password data. An empty shell field is 1618 * legal, and means /bin/sh. 1619 */ 1620 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; 1621 1622 /* 1623 * Make sure $SHELL points to the shell from the password file, 1624 * even if shell is overridden from login.conf 1625 */ 1626 env = do_setup_env(s, shell); 1627 1628#ifdef HAVE_LOGIN_CAP 1629 shell = login_getcapstr(lc, "shell", __UNCONST(shell), 1630 __UNCONST(shell)); 1631#endif 1632 1633 /* we have to stash the hostname before we close our socket. */ 1634 if (options.use_login) 1635 hostname = get_remote_name_or_ip(utmp_len, 1636 options.use_dns); 1637 /* 1638 * Close the connection descriptors; note that this is the child, and 1639 * the server will still have the socket open, and it is important 1640 * that we do not shutdown it. Note that the descriptors cannot be 1641 * closed before building the environment, as we call 1642 * get_remote_ipaddr there. 1643 */ 1644 child_close_fds(); 1645 1646 /* 1647 * Must take new environment into use so that .ssh/rc, 1648 * /etc/ssh/sshrc and xauth are run in the proper environment. 1649 */ 1650 environ = env; 1651 1652#ifdef KRB5 1653 /* 1654 * At this point, we check to see if AFS is active and if we have 1655 * a valid Kerberos 5 TGT. If so, it seems like a good idea to see 1656 * if we can (and need to) extend the ticket into an AFS token. If 1657 * we don't do this, we run into potential problems if the user's 1658 * home directory is in AFS and it's not world-readable. 1659 */ 1660 1661 if (options.kerberos_get_afs_token && k_hasafs() && 1662 (s->authctxt->krb5_ctx != NULL)) { 1663 char cell[64]; 1664 1665 debug("Getting AFS token"); 1666 1667 k_setpag(); 1668 1669 if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0) 1670 krb5_afslog(s->authctxt->krb5_ctx, 1671 s->authctxt->krb5_fwd_ccache, cell, NULL); 1672 1673 krb5_afslog_home(s->authctxt->krb5_ctx, 1674 s->authctxt->krb5_fwd_ccache, NULL, NULL, pw->pw_dir); 1675 } 1676#endif 1677 1678 /* Change current directory to the user's home directory. */ 1679 if (chdir(pw->pw_dir) < 0) { 1680 /* Suppress missing homedir warning for chroot case */ 1681 r = login_getcapbool(lc, "requirehome", 0); 1682 if (r || options.chroot_directory == NULL || 1683 strcasecmp(options.chroot_directory, "none") == 0) 1684 fprintf(stderr, "Could not chdir to home " 1685 "directory %s: %s\n", pw->pw_dir, 1686 strerror(errno)); 1687 if (r) 1688 exit(1); 1689 } 1690 1691 closefrom(STDERR_FILENO + 1); 1692 1693 if (!options.use_login) 1694 do_rc_files(s, shell); 1695 1696 /* restore SIGPIPE for child */ 1697 signal(SIGPIPE, SIG_DFL); 1698 1699 if (s->is_subsystem == SUBSYSTEM_INT_SFTP_ERROR) { 1700 printf("This service allows sftp connections only.\n"); 1701 fflush(NULL); 1702 exit(1); 1703 } else if (s->is_subsystem == SUBSYSTEM_INT_SFTP) { 1704 extern int optind, optreset; 1705 int i; 1706 char *p, *args; 1707 1708 setproctitle("%s@%s", s->pw->pw_name, INTERNAL_SFTP_NAME); 1709 args = xstrdup(command ? command : "sftp-server"); 1710 for (i = 0, (p = strtok(args, " ")); p; (p = strtok(NULL, " "))) 1711 if (i < ARGV_MAX - 1) 1712 argv[i++] = p; 1713 argv[i] = NULL; 1714 optind = optreset = 1; 1715 __progname = argv[0]; 1716 exit(sftp_server_main(i, argv, s->pw)); 1717 } 1718 1719 fflush(NULL); 1720 1721 if (options.use_login) { 1722 launch_login(pw, hostname); 1723 /* NEVERREACHED */ 1724 } 1725 1726 /* Get the last component of the shell name. */ 1727 if ((shell0 = strrchr(shell, '/')) != NULL) 1728 shell0++; 1729 else 1730 shell0 = shell; 1731 1732 /* 1733 * If we have no command, execute the shell. In this case, the shell 1734 * name to be passed in argv[0] is preceded by '-' to indicate that 1735 * this is a login shell. 1736 */ 1737 if (!command) { 1738 char argv0[256]; 1739 1740 /* Start the shell. Set initial character to '-'. */ 1741 argv0[0] = '-'; 1742 1743 if (strlcpy(argv0 + 1, shell0, sizeof(argv0) - 1) 1744 >= sizeof(argv0) - 1) { 1745 errno = EINVAL; 1746 perror(shell); 1747 exit(1); 1748 } 1749 1750 /* Execute the shell. */ 1751 argv[0] = argv0; 1752 argv[1] = NULL; 1753 execve(shell, argv, env); 1754 1755 /* Executing the shell failed. */ 1756 perror(shell); 1757 exit(1); 1758 } 1759 /* 1760 * Execute the command using the user's shell. This uses the -c 1761 * option to execute the command. 1762 */ 1763 argv[0] = __UNCONST(shell0); 1764 argv[1] = __UNCONST("-c"); 1765 argv[2] = __UNCONST(command); 1766 argv[3] = NULL; 1767 execve(shell, argv, env); 1768 perror(shell); 1769 exit(1); 1770} 1771 1772void 1773session_unused(int id) 1774{ 1775 debug3("%s: session id %d unused", __func__, id); 1776 if (id >= options.max_sessions || 1777 id >= sessions_nalloc) { 1778 fatal("%s: insane session id %d (max %d nalloc %d)", 1779 __func__, id, options.max_sessions, sessions_nalloc); 1780 } 1781 memset(&sessions[id], 0, sizeof(*sessions)); 1782 sessions[id].self = id; 1783 sessions[id].used = 0; 1784 sessions[id].chanid = -1; 1785 sessions[id].ptyfd = -1; 1786 sessions[id].ttyfd = -1; 1787 sessions[id].ptymaster = -1; 1788 sessions[id].x11_chanids = NULL; 1789 sessions[id].next_unused = sessions_first_unused; 1790 sessions_first_unused = id; 1791} 1792 1793Session * 1794session_new(void) 1795{ 1796 Session *s, *tmp; 1797 1798 if (sessions_first_unused == -1) { 1799 if (sessions_nalloc >= options.max_sessions) 1800 return NULL; 1801 debug2("%s: allocate (allocated %d max %d)", 1802 __func__, sessions_nalloc, options.max_sessions); 1803 tmp = xrealloc(sessions, sessions_nalloc + 1, 1804 sizeof(*sessions)); 1805 if (tmp == NULL) { 1806 error("%s: cannot allocate %d sessions", 1807 __func__, sessions_nalloc + 1); 1808 return NULL; 1809 } 1810 sessions = tmp; 1811 session_unused(sessions_nalloc++); 1812 } 1813 1814 if (sessions_first_unused >= sessions_nalloc || 1815 sessions_first_unused < 0) { 1816 fatal("%s: insane first_unused %d max %d nalloc %d", 1817 __func__, sessions_first_unused, options.max_sessions, 1818 sessions_nalloc); 1819 } 1820 1821 s = &sessions[sessions_first_unused]; 1822 if (s->used) { 1823 fatal("%s: session %d already used", 1824 __func__, sessions_first_unused); 1825 } 1826 sessions_first_unused = s->next_unused; 1827 s->used = 1; 1828 s->next_unused = -1; 1829 debug("session_new: session %d", s->self); 1830 1831 return s; 1832} 1833 1834static void 1835session_dump(void) 1836{ 1837 int i; 1838 for (i = 0; i < sessions_nalloc; i++) { 1839 Session *s = &sessions[i]; 1840 1841 debug("dump: used %d next_unused %d session %d %p " 1842 "channel %d pid %ld", 1843 s->used, 1844 s->next_unused, 1845 s->self, 1846 s, 1847 s->chanid, 1848 (long)s->pid); 1849 } 1850} 1851 1852int 1853session_open(Authctxt *authctxt, int chanid) 1854{ 1855 Session *s = session_new(); 1856 debug("session_open: channel %d", chanid); 1857 if (s == NULL) { 1858 error("no more sessions"); 1859 return 0; 1860 } 1861 s->authctxt = authctxt; 1862 s->pw = authctxt->pw; 1863 if (s->pw == NULL || !authctxt->valid) 1864 fatal("no user for session %d", s->self); 1865 debug("session_open: session %d: link with channel %d", s->self, chanid); 1866 s->chanid = chanid; 1867 return 1; 1868} 1869 1870Session * 1871session_by_tty(char *tty) 1872{ 1873 int i; 1874 for (i = 0; i < sessions_nalloc; i++) { 1875 Session *s = &sessions[i]; 1876 if (s->used && s->ttyfd != -1 && strcmp(s->tty, tty) == 0) { 1877 debug("session_by_tty: session %d tty %s", i, tty); 1878 return s; 1879 } 1880 } 1881 debug("session_by_tty: unknown tty %.100s", tty); 1882 session_dump(); 1883 return NULL; 1884} 1885 1886static Session * 1887session_by_channel(int id) 1888{ 1889 int i; 1890 for (i = 0; i < sessions_nalloc; i++) { 1891 Session *s = &sessions[i]; 1892 if (s->used && s->chanid == id) { 1893 debug("session_by_channel: session %d channel %d", 1894 i, id); 1895 return s; 1896 } 1897 } 1898 debug("session_by_channel: unknown channel %d", id); 1899 session_dump(); 1900 return NULL; 1901} 1902 1903static Session * 1904session_by_x11_channel(int id) 1905{ 1906 int i, j; 1907 1908 for (i = 0; i < sessions_nalloc; i++) { 1909 Session *s = &sessions[i]; 1910 1911 if (s->x11_chanids == NULL || !s->used) 1912 continue; 1913 for (j = 0; s->x11_chanids[j] != -1; j++) { 1914 if (s->x11_chanids[j] == id) { 1915 debug("session_by_x11_channel: session %d " 1916 "channel %d", s->self, id); 1917 return s; 1918 } 1919 } 1920 } 1921 debug("session_by_x11_channel: unknown channel %d", id); 1922 session_dump(); 1923 return NULL; 1924} 1925 1926static Session * 1927session_by_pid(pid_t pid) 1928{ 1929 int i; 1930 debug("session_by_pid: pid %ld", (long)pid); 1931 for (i = 0; i < sessions_nalloc; i++) { 1932 Session *s = &sessions[i]; 1933 if (s->used && s->pid == pid) 1934 return s; 1935 } 1936 error("session_by_pid: unknown pid %ld", (long)pid); 1937 session_dump(); 1938 return NULL; 1939} 1940 1941static int 1942session_window_change_req(Session *s) 1943{ 1944 s->col = packet_get_int(); 1945 s->row = packet_get_int(); 1946 s->xpixel = packet_get_int(); 1947 s->ypixel = packet_get_int(); 1948 packet_check_eom(); 1949 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 1950 return 1; 1951} 1952 1953static int 1954session_pty_req(Session *s) 1955{ 1956 u_int len; 1957 int n_bytes; 1958 1959 if (no_pty_flag || !options.permit_tty) { 1960 debug("Allocating a pty not permitted for this authentication."); 1961 return 0; 1962 } 1963 if (s->ttyfd != -1) { 1964 packet_disconnect("Protocol error: you already have a pty."); 1965 return 0; 1966 } 1967 1968 s->term = packet_get_string(&len); 1969 1970 if (compat20) { 1971 s->col = packet_get_int(); 1972 s->row = packet_get_int(); 1973 } else { 1974 s->row = packet_get_int(); 1975 s->col = packet_get_int(); 1976 } 1977 s->xpixel = packet_get_int(); 1978 s->ypixel = packet_get_int(); 1979 1980 if (strcmp(s->term, "") == 0) { 1981 free(s->term); 1982 s->term = NULL; 1983 } 1984 1985 /* Allocate a pty and open it. */ 1986 debug("Allocating pty."); 1987 if (!PRIVSEP(pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, 1988 sizeof(s->tty)))) { 1989 free(s->term); 1990 s->term = NULL; 1991 s->ptyfd = -1; 1992 s->ttyfd = -1; 1993 error("session_pty_req: session %d alloc failed", s->self); 1994 return 0; 1995 } 1996 debug("session_pty_req: session %d alloc %s", s->self, s->tty); 1997 1998 /* for SSH1 the tty modes length is not given */ 1999 if (!compat20) 2000 n_bytes = packet_remaining(); 2001 tty_parse_modes(s->ttyfd, &n_bytes); 2002 2003 if (!use_privsep) 2004 pty_setowner(s->pw, s->tty); 2005 2006 /* Set window size from the packet. */ 2007 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 2008 2009 packet_check_eom(); 2010 session_proctitle(s); 2011 return 1; 2012} 2013 2014static int 2015session_subsystem_req(Session *s) 2016{ 2017 struct stat st; 2018 u_int len; 2019 int success = 0; 2020 char *prog, *cmd; 2021 u_int i; 2022 2023 s->subsys = packet_get_string(&len); 2024 packet_check_eom(); 2025 debug2("subsystem request for %.100s by user %s", s->subsys, 2026 s->pw->pw_name); 2027 2028 for (i = 0; i < options.num_subsystems; i++) { 2029 if (strcmp(s->subsys, options.subsystem_name[i]) == 0) { 2030 prog = options.subsystem_command[i]; 2031 cmd = options.subsystem_args[i]; 2032 if (strcmp(INTERNAL_SFTP_NAME, prog) == 0) { 2033 s->is_subsystem = SUBSYSTEM_INT_SFTP; 2034 debug("subsystem: %s", prog); 2035 } else { 2036 if (stat(prog, &st) < 0) 2037 debug("subsystem: cannot stat %s: %s", 2038 prog, strerror(errno)); 2039 s->is_subsystem = SUBSYSTEM_EXT; 2040 debug("subsystem: exec() %s", cmd); 2041 } 2042 success = do_exec(s, cmd) == 0; 2043 break; 2044 } 2045 } 2046 2047 if (!success) 2048 logit("subsystem request for %.100s by user %s failed, " 2049 "subsystem not found", s->subsys, s->pw->pw_name); 2050 2051 return success; 2052} 2053 2054static int 2055session_x11_req(Session *s) 2056{ 2057 int success; 2058 2059 if (s->auth_proto != NULL || s->auth_data != NULL) { 2060 error("session_x11_req: session %d: " 2061 "x11 forwarding already active", s->self); 2062 return 0; 2063 } 2064 s->single_connection = packet_get_char(); 2065 s->auth_proto = packet_get_string(NULL); 2066 s->auth_data = packet_get_string(NULL); 2067 s->screen = packet_get_int(); 2068 packet_check_eom(); 2069 2070 success = session_setup_x11fwd(s); 2071 if (!success) { 2072 free(s->auth_proto); 2073 free(s->auth_data); 2074 s->auth_proto = NULL; 2075 s->auth_data = NULL; 2076 } 2077 return success; 2078} 2079 2080static int 2081session_shell_req(Session *s) 2082{ 2083 packet_check_eom(); 2084 return do_exec(s, NULL) == 0; 2085} 2086 2087static int 2088session_exec_req(Session *s) 2089{ 2090 u_int len, success; 2091 2092 char *command = packet_get_string(&len); 2093 packet_check_eom(); 2094 success = do_exec(s, command) == 0; 2095 free(command); 2096 return success; 2097} 2098 2099static int 2100session_break_req(Session *s) 2101{ 2102 2103 packet_get_int(); /* ignored */ 2104 packet_check_eom(); 2105 2106 if (s->ptymaster == -1 || tcsendbreak(s->ptymaster, 0) < 0) 2107 return 0; 2108 return 1; 2109} 2110 2111static int 2112session_env_req(Session *s) 2113{ 2114 char *name, *val; 2115 u_int name_len, val_len, i; 2116 2117 name = packet_get_cstring(&name_len); 2118 val = packet_get_cstring(&val_len); 2119 packet_check_eom(); 2120 2121 /* Don't set too many environment variables */ 2122 if (s->num_env > 128) { 2123 debug2("Ignoring env request %s: too many env vars", name); 2124 goto fail; 2125 } 2126 2127 for (i = 0; i < options.num_accept_env; i++) { 2128 if (match_pattern(name, options.accept_env[i])) { 2129 debug2("Setting env %d: %s=%s", s->num_env, name, val); 2130 s->env = xrealloc(s->env, s->num_env + 1, 2131 sizeof(*s->env)); 2132 s->env[s->num_env].name = name; 2133 s->env[s->num_env].val = val; 2134 s->num_env++; 2135 return (1); 2136 } 2137 } 2138 debug2("Ignoring env request %s: disallowed name", name); 2139 2140 fail: 2141 free(name); 2142 free(val); 2143 return (0); 2144} 2145 2146static int 2147session_auth_agent_req(Session *s) 2148{ 2149 static int called = 0; 2150 packet_check_eom(); 2151 if (no_agent_forwarding_flag || !options.allow_agent_forwarding) { 2152 debug("session_auth_agent_req: no_agent_forwarding_flag"); 2153 return 0; 2154 } 2155 if (called) { 2156 return 0; 2157 } else { 2158 called = 1; 2159 return auth_input_request_forwarding(s->pw); 2160 } 2161} 2162 2163int 2164session_input_channel_req(Channel *c, const char *rtype) 2165{ 2166 int success = 0; 2167 Session *s; 2168 2169 if ((s = session_by_channel(c->self)) == NULL) { 2170 logit("session_input_channel_req: no session %d req %.100s", 2171 c->self, rtype); 2172 return 0; 2173 } 2174 debug("session_input_channel_req: session %d req %s", s->self, rtype); 2175 2176 /* 2177 * a session is in LARVAL state until a shell, a command 2178 * or a subsystem is executed 2179 */ 2180 if (c->type == SSH_CHANNEL_LARVAL) { 2181 if (strcmp(rtype, "shell") == 0) { 2182 success = session_shell_req(s); 2183 } else if (strcmp(rtype, "exec") == 0) { 2184 success = session_exec_req(s); 2185 } else if (strcmp(rtype, "pty-req") == 0) { 2186 success = session_pty_req(s); 2187 } else if (strcmp(rtype, "x11-req") == 0) { 2188 success = session_x11_req(s); 2189 } else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) { 2190 success = session_auth_agent_req(s); 2191 } else if (strcmp(rtype, "subsystem") == 0) { 2192 success = session_subsystem_req(s); 2193 } else if (strcmp(rtype, "env") == 0) { 2194 success = session_env_req(s); 2195 } 2196 } 2197 if (strcmp(rtype, "window-change") == 0) { 2198 success = session_window_change_req(s); 2199 } else if (strcmp(rtype, "break") == 0) { 2200 success = session_break_req(s); 2201 } 2202 2203 return success; 2204} 2205 2206void 2207session_set_fds(Session *s, int fdin, int fdout, int fderr, int ignore_fderr, 2208 int is_tty) 2209{ 2210 if (!compat20) 2211 fatal("session_set_fds: called for proto != 2.0"); 2212 /* 2213 * now that have a child and a pipe to the child, 2214 * we can activate our channel and register the fd's 2215 */ 2216 if (s->chanid == -1) 2217 fatal("no channel for session %d", s->self); 2218 if(options.hpn_disabled) 2219 channel_set_fds(s->chanid, 2220 fdout, fdin, fderr, 2221 ignore_fderr ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ, 2222 1, is_tty, CHAN_SES_WINDOW_DEFAULT); 2223 else 2224 channel_set_fds(s->chanid, 2225 fdout, fdin, fderr, 2226 ignore_fderr ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ, 2227 1, is_tty, options.hpn_buffer_size); 2228} 2229 2230/* 2231 * Function to perform pty cleanup. Also called if we get aborted abnormally 2232 * (e.g., due to a dropped connection). 2233 */ 2234void 2235session_pty_cleanup2(Session *s) 2236{ 2237 if (s == NULL) { 2238 error("session_pty_cleanup: no session"); 2239 return; 2240 } 2241 if (s->ttyfd == -1) 2242 return; 2243 2244 debug("session_pty_cleanup: session %d release %s", s->self, s->tty); 2245 2246 /* Record that the user has logged out. */ 2247 if (s->pid != 0) 2248 record_logout(s->pid, s->tty); 2249 2250 /* Release the pseudo-tty. */ 2251 if (getuid() == 0) 2252 pty_release(s->tty); 2253 2254 /* 2255 * Close the server side of the socket pairs. We must do this after 2256 * the pty cleanup, so that another process doesn't get this pty 2257 * while we're still cleaning up. 2258 */ 2259 if (s->ptymaster != -1 && close(s->ptymaster) < 0) 2260 error("close(s->ptymaster/%d): %s", 2261 s->ptymaster, strerror(errno)); 2262 2263 /* unlink pty from session */ 2264 s->ttyfd = -1; 2265} 2266 2267void 2268session_pty_cleanup(Session *s) 2269{ 2270 PRIVSEP(session_pty_cleanup2(s)); 2271} 2272 2273static const char * 2274sig2name(int sig) 2275{ 2276#define SSH_SIG(x) if (sig == SIG ## x) return #x 2277 SSH_SIG(ABRT); 2278 SSH_SIG(ALRM); 2279 SSH_SIG(FPE); 2280 SSH_SIG(HUP); 2281 SSH_SIG(ILL); 2282 SSH_SIG(INT); 2283 SSH_SIG(KILL); 2284 SSH_SIG(PIPE); 2285 SSH_SIG(QUIT); 2286 SSH_SIG(SEGV); 2287 SSH_SIG(TERM); 2288 SSH_SIG(USR1); 2289 SSH_SIG(USR2); 2290#undef SSH_SIG 2291 return "SIG@openssh.com"; 2292} 2293 2294static void 2295session_close_x11(int id) 2296{ 2297 Channel *c; 2298 2299 if ((c = channel_by_id(id)) == NULL) { 2300 debug("session_close_x11: x11 channel %d missing", id); 2301 } else { 2302 /* Detach X11 listener */ 2303 debug("session_close_x11: detach x11 channel %d", id); 2304 channel_cancel_cleanup(id); 2305 if (c->ostate != CHAN_OUTPUT_CLOSED) 2306 chan_mark_dead(c); 2307 } 2308} 2309 2310static void 2311session_close_single_x11(int id, void *arg) 2312{ 2313 Session *s; 2314 u_int i; 2315 2316 debug3("session_close_single_x11: channel %d", id); 2317 channel_cancel_cleanup(id); 2318 if ((s = session_by_x11_channel(id)) == NULL) 2319 fatal("session_close_single_x11: no x11 channel %d", id); 2320 for (i = 0; s->x11_chanids[i] != -1; i++) { 2321 debug("session_close_single_x11: session %d: " 2322 "closing channel %d", s->self, s->x11_chanids[i]); 2323 /* 2324 * The channel "id" is already closing, but make sure we 2325 * close all of its siblings. 2326 */ 2327 if (s->x11_chanids[i] != id) 2328 session_close_x11(s->x11_chanids[i]); 2329 } 2330 free(s->x11_chanids); 2331 s->x11_chanids = NULL; 2332 free(s->display); 2333 s->display = NULL; 2334 free(s->auth_proto); 2335 s->auth_proto = NULL; 2336 free(s->auth_data); 2337 s->auth_data = NULL; 2338 free(s->auth_display); 2339 s->auth_display = NULL; 2340} 2341 2342static void 2343session_exit_message(Session *s, int status) 2344{ 2345 Channel *c; 2346 2347 if ((c = channel_lookup(s->chanid)) == NULL) 2348 fatal("session_exit_message: session %d: no channel %d", 2349 s->self, s->chanid); 2350 debug("session_exit_message: session %d channel %d pid %ld", 2351 s->self, s->chanid, (long)s->pid); 2352 2353 if (WIFEXITED(status)) { 2354 channel_request_start(s->chanid, "exit-status", 0); 2355 packet_put_int(WEXITSTATUS(status)); 2356 packet_send(); 2357 } else if (WIFSIGNALED(status)) { 2358 channel_request_start(s->chanid, "exit-signal", 0); 2359 packet_put_cstring(sig2name(WTERMSIG(status))); 2360 packet_put_char(WCOREDUMP(status)? 1 : 0); 2361 packet_put_cstring(""); 2362 packet_put_cstring(""); 2363 packet_send(); 2364 } else { 2365 /* Some weird exit cause. Just exit. */ 2366 packet_disconnect("wait returned status %04x.", status); 2367 } 2368 2369 /* disconnect channel */ 2370 debug("session_exit_message: release channel %d", s->chanid); 2371 2372 /* 2373 * Adjust cleanup callback attachment to send close messages when 2374 * the channel gets EOF. The session will be then be closed 2375 * by session_close_by_channel when the childs close their fds. 2376 */ 2377 channel_register_cleanup(c->self, session_close_by_channel, 1); 2378 2379 /* 2380 * emulate a write failure with 'chan_write_failed', nobody will be 2381 * interested in data we write. 2382 * Note that we must not call 'chan_read_failed', since there could 2383 * be some more data waiting in the pipe. 2384 */ 2385 if (c->ostate != CHAN_OUTPUT_CLOSED) 2386 chan_write_failed(c); 2387} 2388 2389void 2390session_close(Session *s) 2391{ 2392 u_int i; 2393 2394 debug("session_close: session %d pid %ld", s->self, (long)s->pid); 2395 if (s->ttyfd != -1) 2396 session_pty_cleanup(s); 2397 free(s->term); 2398 free(s->display); 2399 free(s->x11_chanids); 2400 free(s->auth_display); 2401 free(s->auth_data); 2402 free(s->auth_proto); 2403 free(s->subsys); 2404 if (s->env != NULL) { 2405 for (i = 0; i < s->num_env; i++) { 2406 free(s->env[i].name); 2407 free(s->env[i].val); 2408 } 2409 free(s->env); 2410 } 2411 session_proctitle(s); 2412 session_unused(s->self); 2413} 2414 2415void 2416session_close_by_pid(pid_t pid, int status) 2417{ 2418 Session *s = session_by_pid(pid); 2419 if (s == NULL) { 2420 debug("session_close_by_pid: no session for pid %ld", 2421 (long)pid); 2422 return; 2423 } 2424 if (s->chanid != -1) 2425 session_exit_message(s, status); 2426 if (s->ttyfd != -1) 2427 session_pty_cleanup(s); 2428 s->pid = 0; 2429} 2430 2431/* 2432 * this is called when a channel dies before 2433 * the session 'child' itself dies 2434 */ 2435void 2436session_close_by_channel(int id, void *arg) 2437{ 2438 Session *s = session_by_channel(id); 2439 u_int i; 2440 2441 if (s == NULL) { 2442 debug("session_close_by_channel: no session for id %d", id); 2443 return; 2444 } 2445 debug("session_close_by_channel: channel %d child %ld", 2446 id, (long)s->pid); 2447 if (s->pid != 0) { 2448 debug("session_close_by_channel: channel %d: has child", id); 2449 /* 2450 * delay detach of session, but release pty, since 2451 * the fd's to the child are already closed 2452 */ 2453 if (s->ttyfd != -1) 2454 session_pty_cleanup(s); 2455 return; 2456 } 2457 /* detach by removing callback */ 2458 channel_cancel_cleanup(s->chanid); 2459 2460 /* Close any X11 listeners associated with this session */ 2461 if (s->x11_chanids != NULL) { 2462 for (i = 0; s->x11_chanids[i] != -1; i++) { 2463 session_close_x11(s->x11_chanids[i]); 2464 s->x11_chanids[i] = -1; 2465 } 2466 } 2467 2468 s->chanid = -1; 2469 session_close(s); 2470} 2471 2472void 2473session_destroy_all(void (*closefunc)(Session *)) 2474{ 2475 int i; 2476 for (i = 0; i < sessions_nalloc; i++) { 2477 Session *s = &sessions[i]; 2478 if (s->used) { 2479 if (closefunc != NULL) 2480 closefunc(s); 2481 else 2482 session_close(s); 2483 } 2484 } 2485} 2486 2487static char * 2488session_tty_list(void) 2489{ 2490 static char buf[1024]; 2491 int i; 2492 buf[0] = '\0'; 2493 for (i = 0; i < sessions_nalloc; i++) { 2494 Session *s = &sessions[i]; 2495 if (s->used && s->ttyfd != -1) { 2496 char *p; 2497 if (buf[0] != '\0') 2498 strlcat(buf, ",", sizeof buf); 2499 if ((p = strstr(s->tty, "/pts/")) != NULL) 2500 p++; 2501 else { 2502 if ((p = strrchr(s->tty, '/')) != NULL) 2503 p++; 2504 else 2505 p = s->tty; 2506 } 2507 strlcat(buf, p, sizeof buf); 2508 } 2509 } 2510 if (buf[0] == '\0') 2511 strlcpy(buf, "notty", sizeof buf); 2512 return buf; 2513} 2514 2515void 2516session_proctitle(Session *s) 2517{ 2518 if (s->pw == NULL) 2519 error("no user for session %d", s->self); 2520 else 2521 setproctitle("%s@%s", s->pw->pw_name, session_tty_list()); 2522} 2523 2524int 2525session_setup_x11fwd(Session *s) 2526{ 2527 struct stat st; 2528 char display[512], auth_display[512]; 2529 char hostname[NI_MAXHOST]; 2530 u_int i; 2531 2532 if (no_x11_forwarding_flag) { 2533 packet_send_debug("X11 forwarding disabled in user configuration file."); 2534 return 0; 2535 } 2536 if (!options.x11_forwarding) { 2537 debug("X11 forwarding disabled in server configuration file."); 2538 return 0; 2539 } 2540 if (options.xauth_location == NULL || 2541 (stat(options.xauth_location, &st) == -1)) { 2542 packet_send_debug("No xauth program; cannot forward with spoofing."); 2543 return 0; 2544 } 2545 if (options.use_login) { 2546 packet_send_debug("X11 forwarding disabled; " 2547 "not compatible with UseLogin=yes."); 2548 return 0; 2549 } 2550 if (s->display != NULL) { 2551 debug("X11 display already set."); 2552 return 0; 2553 } 2554 if (x11_create_display_inet(options.x11_display_offset, 2555 options.x11_use_localhost, s->single_connection, 2556 &s->display_number, &s->x11_chanids) == -1) { 2557 debug("x11_create_display_inet failed."); 2558 return 0; 2559 } 2560 for (i = 0; s->x11_chanids[i] != -1; i++) { 2561 channel_register_cleanup(s->x11_chanids[i], 2562 session_close_single_x11, 0); 2563 } 2564 2565 /* Set up a suitable value for the DISPLAY variable. */ 2566 if (gethostname(hostname, sizeof(hostname)) < 0) 2567 fatal("gethostname: %.100s", strerror(errno)); 2568 /* 2569 * auth_display must be used as the displayname when the 2570 * authorization entry is added with xauth(1). This will be 2571 * different than the DISPLAY string for localhost displays. 2572 */ 2573 if (options.x11_use_localhost) { 2574 snprintf(display, sizeof display, "localhost:%u.%u", 2575 s->display_number, s->screen); 2576 snprintf(auth_display, sizeof auth_display, "unix:%u.%u", 2577 s->display_number, s->screen); 2578 s->display = xstrdup(display); 2579 s->auth_display = xstrdup(auth_display); 2580 } else { 2581 snprintf(display, sizeof display, "%.400s:%u.%u", hostname, 2582 s->display_number, s->screen); 2583 s->display = xstrdup(display); 2584 s->auth_display = xstrdup(display); 2585 } 2586 2587 return 1; 2588} 2589 2590static void 2591do_authenticated2(Authctxt *authctxt) 2592{ 2593 server_loop2(authctxt); 2594} 2595 2596void 2597do_cleanup(Authctxt *authctxt) 2598{ 2599 static int called = 0; 2600 2601 debug("do_cleanup"); 2602 2603 /* no cleanup if we're in the child for login shell */ 2604 if (is_child) 2605 return; 2606 2607 /* avoid double cleanup */ 2608 if (called) 2609 return; 2610 called = 1; 2611 2612 if (authctxt == NULL || !authctxt->authenticated) 2613 return; 2614#ifdef KRB4 2615 if (options.kerberos_ticket_cleanup) 2616 krb4_cleanup_proc(authctxt); 2617#endif 2618#ifdef KRB5 2619 if (options.kerberos_ticket_cleanup && 2620 authctxt->krb5_ctx) 2621 krb5_cleanup_proc(authctxt); 2622#endif 2623 2624#ifdef GSSAPI 2625 if (compat20 && options.gss_cleanup_creds) 2626 ssh_gssapi_cleanup_creds(); 2627#endif 2628 2629#ifdef USE_PAM 2630 if (options.use_pam) { 2631 sshpam_cleanup(); 2632 sshpam_thread_cleanup(); 2633 } 2634#endif 2635 2636 /* remove agent socket */ 2637 auth_sock_cleanup_proc(authctxt->pw); 2638 2639 /* 2640 * Cleanup ptys/utmp only if privsep is disabled, 2641 * or if running in monitor. 2642 */ 2643 if (!use_privsep || mm_is_monitor()) 2644 session_destroy_all(session_pty_cleanup2); 2645} 2646