session.c revision 98941
1/* 2 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 3 * All rights reserved 4 * 5 * As far as I am concerned, the code I have written for this software 6 * can be used freely for any purpose. Any derived versions of this 7 * software must be clearly marked as such, and if the derived work is 8 * incompatible with the protocol description in the RFC file, it must be 9 * called by a name other than "ssh" or "Secure Shell". 10 * 11 * SSH2 support by Markus Friedl. 12 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 13 * 14 * Redistribution and use in source and binary forms, with or without 15 * modification, are permitted provided that the following conditions 16 * are met: 17 * 1. Redistributions of source code must retain the above copyright 18 * notice, this list of conditions and the following disclaimer. 19 * 2. Redistributions in binary form must reproduce the above copyright 20 * notice, this list of conditions and the following disclaimer in the 21 * documentation and/or other materials provided with the distribution. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 24 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 25 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 26 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 27 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 28 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 29 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 30 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 31 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 32 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 33 */ 34 35#include "includes.h" 36RCSID("$OpenBSD: session.c,v 1.138 2002/06/20 23:05:55 markus Exp $"); 37 38#include "ssh.h" 39#include "ssh1.h" 40#include "ssh2.h" 41#include "xmalloc.h" 42#include "sshpty.h" 43#include "packet.h" 44#include "buffer.h" 45#include "mpaux.h" 46#include "uidswap.h" 47#include "compat.h" 48#include "channels.h" 49#include "bufaux.h" 50#include "auth.h" 51#include "auth-options.h" 52#include "pathnames.h" 53#include "log.h" 54#include "servconf.h" 55#include "sshlogin.h" 56#include "serverloop.h" 57#include "canohost.h" 58#include "session.h" 59#include "monitor_wrap.h" 60 61#ifdef HAVE_CYGWIN 62#include <windows.h> 63#include <sys/cygwin.h> 64#define is_winnt (GetVersion() < 0x80000000) 65#endif 66 67/* func */ 68 69Session *session_new(void); 70void session_set_fds(Session *, int, int, int); 71void session_pty_cleanup(void *); 72void session_proctitle(Session *); 73int session_setup_x11fwd(Session *); 74void do_exec_pty(Session *, const char *); 75void do_exec_no_pty(Session *, const char *); 76void do_exec(Session *, const char *); 77void do_login(Session *, const char *); 78#ifdef LOGIN_NEEDS_UTMPX 79static void do_pre_login(Session *s); 80#endif 81void do_child(Session *, const char *); 82void do_motd(void); 83int check_quietlogin(Session *, const char *); 84 85static void do_authenticated1(Authctxt *); 86static void do_authenticated2(Authctxt *); 87 88static int session_pty_req(Session *); 89 90/* import */ 91extern ServerOptions options; 92extern char *__progname; 93extern int log_stderr; 94extern int debug_flag; 95extern u_int utmp_len; 96extern int startup_pipe; 97extern void destroy_sensitive_data(void); 98 99/* original command from peer. */ 100const char *original_command = NULL; 101 102/* data */ 103#define MAX_SESSIONS 10 104Session sessions[MAX_SESSIONS]; 105 106#ifdef WITH_AIXAUTHENTICATE 107char *aixloginmsg; 108#endif /* WITH_AIXAUTHENTICATE */ 109 110#ifdef HAVE_LOGIN_CAP 111login_cap_t *lc; 112#endif 113 114/* Name and directory of socket for authentication agent forwarding. */ 115static char *auth_sock_name = NULL; 116static char *auth_sock_dir = NULL; 117 118/* removes the agent forwarding socket */ 119 120static void 121auth_sock_cleanup_proc(void *_pw) 122{ 123 struct passwd *pw = _pw; 124 125 if (auth_sock_name != NULL) { 126 temporarily_use_uid(pw); 127 unlink(auth_sock_name); 128 rmdir(auth_sock_dir); 129 auth_sock_name = NULL; 130 restore_uid(); 131 } 132} 133 134static int 135auth_input_request_forwarding(struct passwd * pw) 136{ 137 Channel *nc; 138 int sock; 139 struct sockaddr_un sunaddr; 140 141 if (auth_sock_name != NULL) { 142 error("authentication forwarding requested twice."); 143 return 0; 144 } 145 146 /* Temporarily drop privileged uid for mkdir/bind. */ 147 temporarily_use_uid(pw); 148 149 /* Allocate a buffer for the socket name, and format the name. */ 150 auth_sock_name = xmalloc(MAXPATHLEN); 151 auth_sock_dir = xmalloc(MAXPATHLEN); 152 strlcpy(auth_sock_dir, "/tmp/ssh-XXXXXXXX", MAXPATHLEN); 153 154 /* Create private directory for socket */ 155 if (mkdtemp(auth_sock_dir) == NULL) { 156 packet_send_debug("Agent forwarding disabled: " 157 "mkdtemp() failed: %.100s", strerror(errno)); 158 restore_uid(); 159 xfree(auth_sock_name); 160 xfree(auth_sock_dir); 161 auth_sock_name = NULL; 162 auth_sock_dir = NULL; 163 return 0; 164 } 165 snprintf(auth_sock_name, MAXPATHLEN, "%s/agent.%ld", 166 auth_sock_dir, (long) getpid()); 167 168 /* delete agent socket on fatal() */ 169 fatal_add_cleanup(auth_sock_cleanup_proc, pw); 170 171 /* Create the socket. */ 172 sock = socket(AF_UNIX, SOCK_STREAM, 0); 173 if (sock < 0) 174 packet_disconnect("socket: %.100s", strerror(errno)); 175 176 /* Bind it to the name. */ 177 memset(&sunaddr, 0, sizeof(sunaddr)); 178 sunaddr.sun_family = AF_UNIX; 179 strlcpy(sunaddr.sun_path, auth_sock_name, sizeof(sunaddr.sun_path)); 180 181 if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) 182 packet_disconnect("bind: %.100s", strerror(errno)); 183 184 /* Restore the privileged uid. */ 185 restore_uid(); 186 187 /* Start listening on the socket. */ 188 if (listen(sock, 5) < 0) 189 packet_disconnect("listen: %.100s", strerror(errno)); 190 191 /* Allocate a channel for the authentication agent socket. */ 192 nc = channel_new("auth socket", 193 SSH_CHANNEL_AUTH_SOCKET, sock, sock, -1, 194 CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 195 0, xstrdup("auth socket"), 1); 196 strlcpy(nc->path, auth_sock_name, sizeof(nc->path)); 197 return 1; 198} 199 200 201void 202do_authenticated(Authctxt *authctxt) 203{ 204 /* 205 * Cancel the alarm we set to limit the time taken for 206 * authentication. 207 */ 208 alarm(0); 209 if (startup_pipe != -1) { 210 close(startup_pipe); 211 startup_pipe = -1; 212 } 213#ifdef WITH_AIXAUTHENTICATE 214 /* We don't have a pty yet, so just label the line as "ssh" */ 215 if (loginsuccess(authctxt->user, 216 get_canonical_hostname(options.verify_reverse_mapping), 217 "ssh", &aixloginmsg) < 0) 218 aixloginmsg = NULL; 219#endif /* WITH_AIXAUTHENTICATE */ 220 221 /* setup the channel layer */ 222 if (!no_port_forwarding_flag && options.allow_tcp_forwarding) 223 channel_permit_all_opens(); 224 225 if (compat20) 226 do_authenticated2(authctxt); 227 else 228 do_authenticated1(authctxt); 229 230 /* remove agent socket */ 231 if (auth_sock_name != NULL) 232 auth_sock_cleanup_proc(authctxt->pw); 233#ifdef KRB4 234 if (options.kerberos_ticket_cleanup) 235 krb4_cleanup_proc(authctxt); 236#endif 237#ifdef KRB5 238 if (options.kerberos_ticket_cleanup) 239 krb5_cleanup_proc(authctxt); 240#endif 241} 242 243/* 244 * Prepares for an interactive session. This is called after the user has 245 * been successfully authenticated. During this message exchange, pseudo 246 * terminals are allocated, X11, TCP/IP, and authentication agent forwardings 247 * are requested, etc. 248 */ 249static void 250do_authenticated1(Authctxt *authctxt) 251{ 252 Session *s; 253 char *command; 254 int success, type, screen_flag; 255 int compression_level = 0, enable_compression_after_reply = 0; 256 u_int proto_len, data_len, dlen; 257 258 s = session_new(); 259 s->authctxt = authctxt; 260 s->pw = authctxt->pw; 261 262 /* 263 * We stay in this loop until the client requests to execute a shell 264 * or a command. 265 */ 266 for (;;) { 267 success = 0; 268 269 /* Get a packet from the client. */ 270 type = packet_read(); 271 272 /* Process the packet. */ 273 switch (type) { 274 case SSH_CMSG_REQUEST_COMPRESSION: 275 compression_level = packet_get_int(); 276 packet_check_eom(); 277 if (compression_level < 1 || compression_level > 9) { 278 packet_send_debug("Received illegal compression level %d.", 279 compression_level); 280 break; 281 } 282 if (!options.compression) { 283 debug2("compression disabled"); 284 break; 285 } 286 /* Enable compression after we have responded with SUCCESS. */ 287 enable_compression_after_reply = 1; 288 success = 1; 289 break; 290 291 case SSH_CMSG_REQUEST_PTY: 292 success = session_pty_req(s); 293 break; 294 295 case SSH_CMSG_X11_REQUEST_FORWARDING: 296 s->auth_proto = packet_get_string(&proto_len); 297 s->auth_data = packet_get_string(&data_len); 298 299 screen_flag = packet_get_protocol_flags() & 300 SSH_PROTOFLAG_SCREEN_NUMBER; 301 debug2("SSH_PROTOFLAG_SCREEN_NUMBER: %d", screen_flag); 302 303 if (packet_remaining() == 4) { 304 if (!screen_flag) 305 debug2("Buggy client: " 306 "X11 screen flag missing"); 307 s->screen = packet_get_int(); 308 } else { 309 s->screen = 0; 310 } 311 packet_check_eom(); 312 success = session_setup_x11fwd(s); 313 if (!success) { 314 xfree(s->auth_proto); 315 xfree(s->auth_data); 316 s->auth_proto = NULL; 317 s->auth_data = NULL; 318 } 319 break; 320 321 case SSH_CMSG_AGENT_REQUEST_FORWARDING: 322 if (no_agent_forwarding_flag || compat13) { 323 debug("Authentication agent forwarding not permitted for this authentication."); 324 break; 325 } 326 debug("Received authentication agent forwarding request."); 327 success = auth_input_request_forwarding(s->pw); 328 break; 329 330 case SSH_CMSG_PORT_FORWARD_REQUEST: 331 if (no_port_forwarding_flag) { 332 debug("Port forwarding not permitted for this authentication."); 333 break; 334 } 335 if (!options.allow_tcp_forwarding) { 336 debug("Port forwarding not permitted."); 337 break; 338 } 339 debug("Received TCP/IP port forwarding request."); 340 channel_input_port_forward_request(s->pw->pw_uid == 0, options.gateway_ports); 341 success = 1; 342 break; 343 344 case SSH_CMSG_MAX_PACKET_SIZE: 345 if (packet_set_maxsize(packet_get_int()) > 0) 346 success = 1; 347 break; 348 349#if defined(AFS) || defined(KRB5) 350 case SSH_CMSG_HAVE_KERBEROS_TGT: 351 if (!options.kerberos_tgt_passing) { 352 verbose("Kerberos TGT passing disabled."); 353 } else { 354 char *kdata = packet_get_string(&dlen); 355 packet_check_eom(); 356 357 /* XXX - 0x41, see creds_to_radix version */ 358 if (kdata[0] != 0x41) { 359#ifdef KRB5 360 krb5_data tgt; 361 tgt.data = kdata; 362 tgt.length = dlen; 363 364 if (auth_krb5_tgt(s->authctxt, &tgt)) 365 success = 1; 366 else 367 verbose("Kerberos v5 TGT refused for %.100s", s->authctxt->user); 368#endif /* KRB5 */ 369 } else { 370#ifdef AFS 371 if (auth_krb4_tgt(s->authctxt, kdata)) 372 success = 1; 373 else 374 verbose("Kerberos v4 TGT refused for %.100s", s->authctxt->user); 375#endif /* AFS */ 376 } 377 xfree(kdata); 378 } 379 break; 380#endif /* AFS || KRB5 */ 381 382#ifdef AFS 383 case SSH_CMSG_HAVE_AFS_TOKEN: 384 if (!options.afs_token_passing || !k_hasafs()) { 385 verbose("AFS token passing disabled."); 386 } else { 387 /* Accept AFS token. */ 388 char *token = packet_get_string(&dlen); 389 packet_check_eom(); 390 391 if (auth_afs_token(s->authctxt, token)) 392 success = 1; 393 else 394 verbose("AFS token refused for %.100s", 395 s->authctxt->user); 396 xfree(token); 397 } 398 break; 399#endif /* AFS */ 400 401 case SSH_CMSG_EXEC_SHELL: 402 case SSH_CMSG_EXEC_CMD: 403 if (type == SSH_CMSG_EXEC_CMD) { 404 command = packet_get_string(&dlen); 405 debug("Exec command '%.500s'", command); 406 do_exec(s, command); 407 xfree(command); 408 } else { 409 do_exec(s, NULL); 410 } 411 packet_check_eom(); 412 session_close(s); 413 return; 414 415 default: 416 /* 417 * Any unknown messages in this phase are ignored, 418 * and a failure message is returned. 419 */ 420 log("Unknown packet type received after authentication: %d", type); 421 } 422 packet_start(success ? SSH_SMSG_SUCCESS : SSH_SMSG_FAILURE); 423 packet_send(); 424 packet_write_wait(); 425 426 /* Enable compression now that we have replied if appropriate. */ 427 if (enable_compression_after_reply) { 428 enable_compression_after_reply = 0; 429 packet_start_compression(compression_level); 430 } 431 } 432} 433 434/* 435 * This is called to fork and execute a command when we have no tty. This 436 * will call do_child from the child, and server_loop from the parent after 437 * setting up file descriptors and such. 438 */ 439void 440do_exec_no_pty(Session *s, const char *command) 441{ 442 pid_t pid; 443 444#ifdef USE_PIPES 445 int pin[2], pout[2], perr[2]; 446 /* Allocate pipes for communicating with the program. */ 447 if (pipe(pin) < 0 || pipe(pout) < 0 || pipe(perr) < 0) 448 packet_disconnect("Could not create pipes: %.100s", 449 strerror(errno)); 450#else /* USE_PIPES */ 451 int inout[2], err[2]; 452 /* Uses socket pairs to communicate with the program. */ 453 if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) < 0 || 454 socketpair(AF_UNIX, SOCK_STREAM, 0, err) < 0) 455 packet_disconnect("Could not create socket pairs: %.100s", 456 strerror(errno)); 457#endif /* USE_PIPES */ 458 if (s == NULL) 459 fatal("do_exec_no_pty: no session"); 460 461 session_proctitle(s); 462 463#if defined(USE_PAM) 464 do_pam_session(s->pw->pw_name, NULL); 465 do_pam_setcred(1); 466 if (is_pam_password_change_required()) 467 packet_disconnect("Password change required but no " 468 "TTY available"); 469#endif /* USE_PAM */ 470 471 /* Fork the child. */ 472 if ((pid = fork()) == 0) { 473 /* Child. Reinitialize the log since the pid has changed. */ 474 log_init(__progname, options.log_level, options.log_facility, log_stderr); 475 476 /* 477 * Create a new session and process group since the 4.4BSD 478 * setlogin() affects the entire process group. 479 */ 480 if (setsid() < 0) 481 error("setsid failed: %.100s", strerror(errno)); 482 483#ifdef USE_PIPES 484 /* 485 * Redirect stdin. We close the parent side of the socket 486 * pair, and make the child side the standard input. 487 */ 488 close(pin[1]); 489 if (dup2(pin[0], 0) < 0) 490 perror("dup2 stdin"); 491 close(pin[0]); 492 493 /* Redirect stdout. */ 494 close(pout[0]); 495 if (dup2(pout[1], 1) < 0) 496 perror("dup2 stdout"); 497 close(pout[1]); 498 499 /* Redirect stderr. */ 500 close(perr[0]); 501 if (dup2(perr[1], 2) < 0) 502 perror("dup2 stderr"); 503 close(perr[1]); 504#else /* USE_PIPES */ 505 /* 506 * Redirect stdin, stdout, and stderr. Stdin and stdout will 507 * use the same socket, as some programs (particularly rdist) 508 * seem to depend on it. 509 */ 510 close(inout[1]); 511 close(err[1]); 512 if (dup2(inout[0], 0) < 0) /* stdin */ 513 perror("dup2 stdin"); 514 if (dup2(inout[0], 1) < 0) /* stdout. Note: same socket as stdin. */ 515 perror("dup2 stdout"); 516 if (dup2(err[0], 2) < 0) /* stderr */ 517 perror("dup2 stderr"); 518#endif /* USE_PIPES */ 519 520 /* Do processing for the child (exec command etc). */ 521 do_child(s, command); 522 /* NOTREACHED */ 523 } 524#ifdef HAVE_CYGWIN 525 if (is_winnt) 526 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); 527#endif 528 if (pid < 0) 529 packet_disconnect("fork failed: %.100s", strerror(errno)); 530 s->pid = pid; 531 /* Set interactive/non-interactive mode. */ 532 packet_set_interactive(s->display != NULL); 533#ifdef USE_PIPES 534 /* We are the parent. Close the child sides of the pipes. */ 535 close(pin[0]); 536 close(pout[1]); 537 close(perr[1]); 538 539 if (compat20) { 540 session_set_fds(s, pin[1], pout[0], s->is_subsystem ? -1 : perr[0]); 541 } else { 542 /* Enter the interactive session. */ 543 server_loop(pid, pin[1], pout[0], perr[0]); 544 /* server_loop has closed pin[1], pout[0], and perr[0]. */ 545 } 546#else /* USE_PIPES */ 547 /* We are the parent. Close the child sides of the socket pairs. */ 548 close(inout[0]); 549 close(err[0]); 550 551 /* 552 * Enter the interactive session. Note: server_loop must be able to 553 * handle the case that fdin and fdout are the same. 554 */ 555 if (compat20) { 556 session_set_fds(s, inout[1], inout[1], s->is_subsystem ? -1 : err[1]); 557 } else { 558 server_loop(pid, inout[1], inout[1], err[1]); 559 /* server_loop has closed inout[1] and err[1]. */ 560 } 561#endif /* USE_PIPES */ 562} 563 564/* 565 * This is called to fork and execute a command when we have a tty. This 566 * will call do_child from the child, and server_loop from the parent after 567 * setting up file descriptors, controlling tty, updating wtmp, utmp, 568 * lastlog, and other such operations. 569 */ 570void 571do_exec_pty(Session *s, const char *command) 572{ 573 int fdout, ptyfd, ttyfd, ptymaster; 574 pid_t pid; 575 576 if (s == NULL) 577 fatal("do_exec_pty: no session"); 578 ptyfd = s->ptyfd; 579 ttyfd = s->ttyfd; 580 581#if defined(USE_PAM) 582 do_pam_session(s->pw->pw_name, s->tty); 583 do_pam_setcred(1); 584#endif 585 586 /* Fork the child. */ 587 if ((pid = fork()) == 0) { 588 589 /* Child. Reinitialize the log because the pid has changed. */ 590 log_init(__progname, options.log_level, options.log_facility, log_stderr); 591 /* Close the master side of the pseudo tty. */ 592 close(ptyfd); 593 594 /* Make the pseudo tty our controlling tty. */ 595 pty_make_controlling_tty(&ttyfd, s->tty); 596 597 /* Redirect stdin/stdout/stderr from the pseudo tty. */ 598 if (dup2(ttyfd, 0) < 0) 599 error("dup2 stdin: %s", strerror(errno)); 600 if (dup2(ttyfd, 1) < 0) 601 error("dup2 stdout: %s", strerror(errno)); 602 if (dup2(ttyfd, 2) < 0) 603 error("dup2 stderr: %s", strerror(errno)); 604 605 /* Close the extra descriptor for the pseudo tty. */ 606 close(ttyfd); 607 608 /* record login, etc. similar to login(1) */ 609#ifndef HAVE_OSF_SIA 610 if (!(options.use_login && command == NULL)) 611 do_login(s, command); 612# ifdef LOGIN_NEEDS_UTMPX 613 else 614 do_pre_login(s); 615# endif 616#endif 617 618 /* Do common processing for the child, such as execing the command. */ 619 do_child(s, command); 620 /* NOTREACHED */ 621 } 622#ifdef HAVE_CYGWIN 623 if (is_winnt) 624 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); 625#endif 626 if (pid < 0) 627 packet_disconnect("fork failed: %.100s", strerror(errno)); 628 s->pid = pid; 629 630 /* Parent. Close the slave side of the pseudo tty. */ 631 close(ttyfd); 632 633 /* 634 * Create another descriptor of the pty master side for use as the 635 * standard input. We could use the original descriptor, but this 636 * simplifies code in server_loop. The descriptor is bidirectional. 637 */ 638 fdout = dup(ptyfd); 639 if (fdout < 0) 640 packet_disconnect("dup #1 failed: %.100s", strerror(errno)); 641 642 /* we keep a reference to the pty master */ 643 ptymaster = dup(ptyfd); 644 if (ptymaster < 0) 645 packet_disconnect("dup #2 failed: %.100s", strerror(errno)); 646 s->ptymaster = ptymaster; 647 648 /* Enter interactive session. */ 649 packet_set_interactive(1); 650 if (compat20) { 651 session_set_fds(s, ptyfd, fdout, -1); 652 } else { 653 server_loop(pid, ptyfd, fdout, -1); 654 /* server_loop _has_ closed ptyfd and fdout. */ 655 } 656} 657 658#ifdef LOGIN_NEEDS_UTMPX 659static void 660do_pre_login(Session *s) 661{ 662 socklen_t fromlen; 663 struct sockaddr_storage from; 664 pid_t pid = getpid(); 665 666 /* 667 * Get IP address of client. If the connection is not a socket, let 668 * the address be 0.0.0.0. 669 */ 670 memset(&from, 0, sizeof(from)); 671 if (packet_connection_is_on_socket()) { 672 fromlen = sizeof(from); 673 if (getpeername(packet_get_connection_in(), 674 (struct sockaddr *) & from, &fromlen) < 0) { 675 debug("getpeername: %.100s", strerror(errno)); 676 fatal_cleanup(); 677 } 678 } 679 680 record_utmp_only(pid, s->tty, s->pw->pw_name, 681 get_remote_name_or_ip(utmp_len, options.verify_reverse_mapping), 682 (struct sockaddr *)&from); 683} 684#endif 685 686/* 687 * This is called to fork and execute a command. If another command is 688 * to be forced, execute that instead. 689 */ 690void 691do_exec(Session *s, const char *command) 692{ 693 if (forced_command) { 694 original_command = command; 695 command = forced_command; 696 debug("Forced command '%.900s'", command); 697 } 698 699 if (s->ttyfd != -1) 700 do_exec_pty(s, command); 701 else 702 do_exec_no_pty(s, command); 703 704 original_command = NULL; 705} 706 707 708/* administrative, login(1)-like work */ 709void 710do_login(Session *s, const char *command) 711{ 712 char *time_string; 713 socklen_t fromlen; 714 struct sockaddr_storage from; 715 struct passwd * pw = s->pw; 716 pid_t pid = getpid(); 717 718 /* 719 * Get IP address of client. If the connection is not a socket, let 720 * the address be 0.0.0.0. 721 */ 722 memset(&from, 0, sizeof(from)); 723 if (packet_connection_is_on_socket()) { 724 fromlen = sizeof(from); 725 if (getpeername(packet_get_connection_in(), 726 (struct sockaddr *) & from, &fromlen) < 0) { 727 debug("getpeername: %.100s", strerror(errno)); 728 fatal_cleanup(); 729 } 730 } 731 732 /* Record that there was a login on that tty from the remote host. */ 733 if (!use_privsep) 734 record_login(pid, s->tty, pw->pw_name, pw->pw_uid, 735 get_remote_name_or_ip(utmp_len, 736 options.verify_reverse_mapping), 737 (struct sockaddr *)&from); 738 739#ifdef USE_PAM 740 /* 741 * If password change is needed, do it now. 742 * This needs to occur before the ~/.hushlogin check. 743 */ 744 if (is_pam_password_change_required()) { 745 print_pam_messages(); 746 do_pam_chauthtok(); 747 } 748#endif 749 750 if (check_quietlogin(s, command)) 751 return; 752 753#ifdef USE_PAM 754 if (!is_pam_password_change_required()) 755 print_pam_messages(); 756#endif /* USE_PAM */ 757#ifdef WITH_AIXAUTHENTICATE 758 if (aixloginmsg && *aixloginmsg) 759 printf("%s\n", aixloginmsg); 760#endif /* WITH_AIXAUTHENTICATE */ 761 762 if (options.print_lastlog && s->last_login_time != 0) { 763 time_string = ctime(&s->last_login_time); 764 if (strchr(time_string, '\n')) 765 *strchr(time_string, '\n') = 0; 766 if (strcmp(s->hostname, "") == 0) 767 printf("Last login: %s\r\n", time_string); 768 else 769 printf("Last login: %s from %s\r\n", time_string, 770 s->hostname); 771 } 772 773 do_motd(); 774} 775 776/* 777 * Display the message of the day. 778 */ 779void 780do_motd(void) 781{ 782 FILE *f; 783 char buf[256]; 784 785 if (options.print_motd) { 786#ifdef HAVE_LOGIN_CAP 787 f = fopen(login_getcapstr(lc, "welcome", "/etc/motd", 788 "/etc/motd"), "r"); 789#else 790 f = fopen("/etc/motd", "r"); 791#endif 792 if (f) { 793 while (fgets(buf, sizeof(buf), f)) 794 fputs(buf, stdout); 795 fclose(f); 796 } 797 } 798} 799 800 801/* 802 * Check for quiet login, either .hushlogin or command given. 803 */ 804int 805check_quietlogin(Session *s, const char *command) 806{ 807 char buf[256]; 808 struct passwd *pw = s->pw; 809 struct stat st; 810 811 /* Return 1 if .hushlogin exists or a command given. */ 812 if (command != NULL) 813 return 1; 814 snprintf(buf, sizeof(buf), "%.200s/.hushlogin", pw->pw_dir); 815#ifdef HAVE_LOGIN_CAP 816 if (login_getcapbool(lc, "hushlogin", 0) || stat(buf, &st) >= 0) 817 return 1; 818#else 819 if (stat(buf, &st) >= 0) 820 return 1; 821#endif 822 return 0; 823} 824 825/* 826 * Sets the value of the given variable in the environment. If the variable 827 * already exists, its value is overriden. 828 */ 829static void 830child_set_env(char ***envp, u_int *envsizep, const char *name, 831 const char *value) 832{ 833 u_int i, namelen; 834 char **env; 835 836 /* 837 * Find the slot where the value should be stored. If the variable 838 * already exists, we reuse the slot; otherwise we append a new slot 839 * at the end of the array, expanding if necessary. 840 */ 841 env = *envp; 842 namelen = strlen(name); 843 for (i = 0; env[i]; i++) 844 if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=') 845 break; 846 if (env[i]) { 847 /* Reuse the slot. */ 848 xfree(env[i]); 849 } else { 850 /* New variable. Expand if necessary. */ 851 if (i >= (*envsizep) - 1) { 852 (*envsizep) += 50; 853 env = (*envp) = xrealloc(env, (*envsizep) * sizeof(char *)); 854 } 855 /* Need to set the NULL pointer at end of array beyond the new slot. */ 856 env[i + 1] = NULL; 857 } 858 859 /* Allocate space and format the variable in the appropriate slot. */ 860 env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1); 861 snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value); 862} 863 864/* 865 * Reads environment variables from the given file and adds/overrides them 866 * into the environment. If the file does not exist, this does nothing. 867 * Otherwise, it must consist of empty lines, comments (line starts with '#') 868 * and assignments of the form name=value. No other forms are allowed. 869 */ 870static void 871read_environment_file(char ***env, u_int *envsize, 872 const char *filename) 873{ 874 FILE *f; 875 char buf[4096]; 876 char *cp, *value; 877 878 f = fopen(filename, "r"); 879 if (!f) 880 return; 881 882 while (fgets(buf, sizeof(buf), f)) { 883 for (cp = buf; *cp == ' ' || *cp == '\t'; cp++) 884 ; 885 if (!*cp || *cp == '#' || *cp == '\n') 886 continue; 887 if (strchr(cp, '\n')) 888 *strchr(cp, '\n') = '\0'; 889 value = strchr(cp, '='); 890 if (value == NULL) { 891 fprintf(stderr, "Bad line in %.100s: %.200s\n", filename, buf); 892 continue; 893 } 894 /* 895 * Replace the equals sign by nul, and advance value to 896 * the value string. 897 */ 898 *value = '\0'; 899 value++; 900 child_set_env(env, envsize, cp, value); 901 } 902 fclose(f); 903} 904 905void copy_environment(char **source, char ***env, u_int *envsize) 906{ 907 char *var_name, *var_val; 908 int i; 909 910 if (source == NULL) 911 return; 912 913 for(i = 0; source[i] != NULL; i++) { 914 var_name = xstrdup(source[i]); 915 if ((var_val = strstr(var_name, "=")) == NULL) { 916 xfree(var_name); 917 continue; 918 } 919 *var_val++ = '\0'; 920 921 debug3("Copy environment: %s=%s", var_name, var_val); 922 child_set_env(env, envsize, var_name, var_val); 923 924 xfree(var_name); 925 } 926} 927 928static char ** 929do_setup_env(Session *s, const char *shell) 930{ 931 char buf[256]; 932 u_int i, envsize; 933 char **env; 934 struct passwd *pw = s->pw; 935 936 /* Initialize the environment. */ 937 envsize = 100; 938 env = xmalloc(envsize * sizeof(char *)); 939 env[0] = NULL; 940 941#ifdef HAVE_CYGWIN 942 /* 943 * The Windows environment contains some setting which are 944 * important for a running system. They must not be dropped. 945 */ 946 copy_environment(environ, &env, &envsize); 947#endif 948 949 if (!options.use_login) { 950 /* Set basic environment. */ 951 child_set_env(&env, &envsize, "USER", pw->pw_name); 952 child_set_env(&env, &envsize, "LOGNAME", pw->pw_name); 953 child_set_env(&env, &envsize, "HOME", pw->pw_dir); 954#ifdef HAVE_LOGIN_CAP 955 (void) setusercontext(lc, pw, pw->pw_uid, LOGIN_SETPATH); 956 child_set_env(&env, &envsize, "PATH", getenv("PATH")); 957#else /* HAVE_LOGIN_CAP */ 958# ifndef HAVE_CYGWIN 959 /* 960 * There's no standard path on Windows. The path contains 961 * important components pointing to the system directories, 962 * needed for loading shared libraries. So the path better 963 * remains intact here. 964 */ 965# ifdef SUPERUSER_PATH 966 child_set_env(&env, &envsize, "PATH", 967 s->pw->pw_uid == 0 ? SUPERUSER_PATH : _PATH_STDPATH); 968# else 969 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); 970# endif /* SUPERUSER_PATH */ 971# endif /* HAVE_CYGWIN */ 972#endif /* HAVE_LOGIN_CAP */ 973 974 snprintf(buf, sizeof buf, "%.200s/%.50s", 975 _PATH_MAILDIR, pw->pw_name); 976 child_set_env(&env, &envsize, "MAIL", buf); 977 978 /* Normal systems set SHELL by default. */ 979 child_set_env(&env, &envsize, "SHELL", shell); 980 } 981 if (getenv("TZ")) 982 child_set_env(&env, &envsize, "TZ", getenv("TZ")); 983 984 /* Set custom environment options from RSA authentication. */ 985 if (!options.use_login) { 986 while (custom_environment) { 987 struct envstring *ce = custom_environment; 988 char *s = ce->s; 989 990 for (i = 0; s[i] != '=' && s[i]; i++) 991 ; 992 if (s[i] == '=') { 993 s[i] = 0; 994 child_set_env(&env, &envsize, s, s + i + 1); 995 } 996 custom_environment = ce->next; 997 xfree(ce->s); 998 xfree(ce); 999 } 1000 } 1001 1002 snprintf(buf, sizeof buf, "%.50s %d %d", 1003 get_remote_ipaddr(), get_remote_port(), get_local_port()); 1004 child_set_env(&env, &envsize, "SSH_CLIENT", buf); 1005 1006 if (s->ttyfd != -1) 1007 child_set_env(&env, &envsize, "SSH_TTY", s->tty); 1008 if (s->term) 1009 child_set_env(&env, &envsize, "TERM", s->term); 1010 if (s->display) 1011 child_set_env(&env, &envsize, "DISPLAY", s->display); 1012 if (original_command) 1013 child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND", 1014 original_command); 1015 1016#ifdef _AIX 1017 { 1018 char *cp; 1019 1020 if ((cp = getenv("AUTHSTATE")) != NULL) 1021 child_set_env(&env, &envsize, "AUTHSTATE", cp); 1022 if ((cp = getenv("KRB5CCNAME")) != NULL) 1023 child_set_env(&env, &envsize, "KRB5CCNAME", cp); 1024 read_environment_file(&env, &envsize, "/etc/environment"); 1025 } 1026#endif 1027#ifdef KRB4 1028 if (s->authctxt->krb4_ticket_file) 1029 child_set_env(&env, &envsize, "KRBTKFILE", 1030 s->authctxt->krb4_ticket_file); 1031#endif 1032#ifdef KRB5 1033 if (s->authctxt->krb5_ticket_file) 1034 child_set_env(&env, &envsize, "KRB5CCNAME", 1035 s->authctxt->krb5_ticket_file); 1036#endif 1037#ifdef USE_PAM 1038 /* Pull in any environment variables that may have been set by PAM. */ 1039 copy_environment(fetch_pam_environment(), &env, &envsize); 1040#endif /* USE_PAM */ 1041 1042 if (auth_sock_name != NULL) 1043 child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME, 1044 auth_sock_name); 1045 1046 /* read $HOME/.ssh/environment. */ 1047 if (!options.use_login) { 1048 snprintf(buf, sizeof buf, "%.200s/.ssh/environment", 1049 pw->pw_dir); 1050 read_environment_file(&env, &envsize, buf); 1051 } 1052 if (debug_flag) { 1053 /* dump the environment */ 1054 fprintf(stderr, "Environment:\n"); 1055 for (i = 0; env[i]; i++) 1056 fprintf(stderr, " %.200s\n", env[i]); 1057 } 1058 return env; 1059} 1060 1061/* 1062 * Run $HOME/.ssh/rc, /etc/ssh/sshrc, or xauth (whichever is found 1063 * first in this order). 1064 */ 1065static void 1066do_rc_files(Session *s, const char *shell) 1067{ 1068 FILE *f = NULL; 1069 char cmd[1024]; 1070 int do_xauth; 1071 struct stat st; 1072 1073 do_xauth = 1074 s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL; 1075 1076 /* ignore _PATH_SSH_USER_RC for subsystems */ 1077 if (!s->is_subsystem && (stat(_PATH_SSH_USER_RC, &st) >= 0)) { 1078 snprintf(cmd, sizeof cmd, "%s -c '%s %s'", 1079 shell, _PATH_BSHELL, _PATH_SSH_USER_RC); 1080 if (debug_flag) 1081 fprintf(stderr, "Running %s\n", cmd); 1082 f = popen(cmd, "w"); 1083 if (f) { 1084 if (do_xauth) 1085 fprintf(f, "%s %s\n", s->auth_proto, 1086 s->auth_data); 1087 pclose(f); 1088 } else 1089 fprintf(stderr, "Could not run %s\n", 1090 _PATH_SSH_USER_RC); 1091 } else if (stat(_PATH_SSH_SYSTEM_RC, &st) >= 0) { 1092 if (debug_flag) 1093 fprintf(stderr, "Running %s %s\n", _PATH_BSHELL, 1094 _PATH_SSH_SYSTEM_RC); 1095 f = popen(_PATH_BSHELL " " _PATH_SSH_SYSTEM_RC, "w"); 1096 if (f) { 1097 if (do_xauth) 1098 fprintf(f, "%s %s\n", s->auth_proto, 1099 s->auth_data); 1100 pclose(f); 1101 } else 1102 fprintf(stderr, "Could not run %s\n", 1103 _PATH_SSH_SYSTEM_RC); 1104 } else if (do_xauth && options.xauth_location != NULL) { 1105 /* Add authority data to .Xauthority if appropriate. */ 1106 if (debug_flag) { 1107 fprintf(stderr, 1108 "Running %.500s add " 1109 "%.100s %.100s %.100s\n", 1110 options.xauth_location, s->auth_display, 1111 s->auth_proto, s->auth_data); 1112 } 1113 snprintf(cmd, sizeof cmd, "%s -q -", 1114 options.xauth_location); 1115 f = popen(cmd, "w"); 1116 if (f) { 1117 fprintf(f, "add %s %s %s\n", 1118 s->auth_display, s->auth_proto, 1119 s->auth_data); 1120 pclose(f); 1121 } else { 1122 fprintf(stderr, "Could not run %s\n", 1123 cmd); 1124 } 1125 } 1126} 1127 1128static void 1129do_nologin(struct passwd *pw) 1130{ 1131 FILE *f = NULL; 1132 char buf[1024]; 1133 1134#ifdef HAVE_LOGIN_CAP 1135 if (!login_getcapbool(lc, "ignorenologin", 0) && pw->pw_uid) 1136 f = fopen(login_getcapstr(lc, "nologin", _PATH_NOLOGIN, 1137 _PATH_NOLOGIN), "r"); 1138#else 1139 if (pw->pw_uid) 1140 f = fopen(_PATH_NOLOGIN, "r"); 1141#endif 1142 if (f) { 1143 /* /etc/nologin exists. Print its contents and exit. */ 1144 while (fgets(buf, sizeof(buf), f)) 1145 fputs(buf, stderr); 1146 fclose(f); 1147 exit(254); 1148 } 1149} 1150 1151/* Set login name, uid, gid, and groups. */ 1152void 1153do_setusercontext(struct passwd *pw) 1154{ 1155#ifdef HAVE_CYGWIN 1156 if (is_winnt) { 1157#else /* HAVE_CYGWIN */ 1158 if (getuid() == 0 || geteuid() == 0) { 1159#endif /* HAVE_CYGWIN */ 1160#ifdef HAVE_SETPCRED 1161 setpcred(pw->pw_name); 1162#endif /* HAVE_SETPCRED */ 1163#ifdef HAVE_LOGIN_CAP 1164 if (setusercontext(lc, pw, pw->pw_uid, 1165 (LOGIN_SETALL & ~LOGIN_SETPATH)) < 0) { 1166 perror("unable to set user context"); 1167 exit(1); 1168 } 1169#else 1170# if defined(HAVE_GETLUID) && defined(HAVE_SETLUID) 1171 /* Sets login uid for accounting */ 1172 if (getluid() == -1 && setluid(pw->pw_uid) == -1) 1173 error("setluid: %s", strerror(errno)); 1174# endif /* defined(HAVE_GETLUID) && defined(HAVE_SETLUID) */ 1175 1176 if (setlogin(pw->pw_name) < 0) 1177 error("setlogin failed: %s", strerror(errno)); 1178 if (setgid(pw->pw_gid) < 0) { 1179 perror("setgid"); 1180 exit(1); 1181 } 1182 /* Initialize the group list. */ 1183 if (initgroups(pw->pw_name, pw->pw_gid) < 0) { 1184 perror("initgroups"); 1185 exit(1); 1186 } 1187 endgrent(); 1188# ifdef USE_PAM 1189 /* 1190 * PAM credentials may take the form of supplementary groups. 1191 * These will have been wiped by the above initgroups() call. 1192 * Reestablish them here. 1193 */ 1194 do_pam_setcred(0); 1195# endif /* USE_PAM */ 1196# if defined(WITH_IRIX_PROJECT) || defined(WITH_IRIX_JOBS) || defined(WITH_IRIX_ARRAY) 1197 irix_setusercontext(pw); 1198# endif /* defined(WITH_IRIX_PROJECT) || defined(WITH_IRIX_JOBS) || defined(WITH_IRIX_ARRAY) */ 1199 /* Permanently switch to the desired uid. */ 1200 permanently_set_uid(pw); 1201#endif 1202 } 1203 if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) 1204 fatal("Failed to set uids to %u.", (u_int) pw->pw_uid); 1205} 1206 1207static void 1208launch_login(struct passwd *pw, const char *hostname) 1209{ 1210 /* Launch login(1). */ 1211 1212 execl(LOGIN_PROGRAM, "login", "-h", hostname, 1213#ifdef xxxLOGIN_NEEDS_TERM 1214 (s->term ? s->term : "unknown"), 1215#endif /* LOGIN_NEEDS_TERM */ 1216#ifdef LOGIN_NO_ENDOPT 1217 "-p", "-f", pw->pw_name, (char *)NULL); 1218#else 1219 "-p", "-f", "--", pw->pw_name, (char *)NULL); 1220#endif 1221 1222 /* Login couldn't be executed, die. */ 1223 1224 perror("login"); 1225 exit(1); 1226} 1227 1228/* 1229 * Performs common processing for the child, such as setting up the 1230 * environment, closing extra file descriptors, setting the user and group 1231 * ids, and executing the command or shell. 1232 */ 1233void 1234do_child(Session *s, const char *command) 1235{ 1236 extern char **environ; 1237 char **env; 1238 char *argv[10]; 1239 const char *shell, *shell0, *hostname = NULL; 1240 struct passwd *pw = s->pw; 1241 u_int i; 1242 1243 /* remove hostkey from the child's memory */ 1244 destroy_sensitive_data(); 1245 1246 /* login(1) is only called if we execute the login shell */ 1247 if (options.use_login && command != NULL) 1248 options.use_login = 0; 1249 1250 /* 1251 * Login(1) does this as well, and it needs uid 0 for the "-h" 1252 * switch, so we let login(1) to this for us. 1253 */ 1254 if (!options.use_login) { 1255#ifdef HAVE_OSF_SIA 1256 session_setup_sia(pw->pw_name, s->ttyfd == -1 ? NULL : s->tty); 1257 if (!check_quietlogin(s, command)) 1258 do_motd(); 1259#else /* HAVE_OSF_SIA */ 1260 do_nologin(pw); 1261# ifdef _AIX 1262 aix_usrinfo(pw, s->tty, s->ttyfd); 1263# endif /* _AIX */ 1264 do_setusercontext(pw); 1265#endif /* HAVE_OSF_SIA */ 1266 } 1267 1268 /* 1269 * Get the shell from the password data. An empty shell field is 1270 * legal, and means /bin/sh. 1271 */ 1272 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; 1273#ifdef HAVE_LOGIN_CAP 1274 shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell); 1275#endif 1276 1277 env = do_setup_env(s, shell); 1278 1279 /* we have to stash the hostname before we close our socket. */ 1280 if (options.use_login) 1281 hostname = get_remote_name_or_ip(utmp_len, 1282 options.verify_reverse_mapping); 1283 /* 1284 * Close the connection descriptors; note that this is the child, and 1285 * the server will still have the socket open, and it is important 1286 * that we do not shutdown it. Note that the descriptors cannot be 1287 * closed before building the environment, as we call 1288 * get_remote_ipaddr there. 1289 */ 1290 if (packet_get_connection_in() == packet_get_connection_out()) 1291 close(packet_get_connection_in()); 1292 else { 1293 close(packet_get_connection_in()); 1294 close(packet_get_connection_out()); 1295 } 1296 /* 1297 * Close all descriptors related to channels. They will still remain 1298 * open in the parent. 1299 */ 1300 /* XXX better use close-on-exec? -markus */ 1301 channel_close_all(); 1302 1303 /* 1304 * Close any extra file descriptors. Note that there may still be 1305 * descriptors left by system functions. They will be closed later. 1306 */ 1307 endpwent(); 1308 1309 /* 1310 * Close any extra open file descriptors so that we don\'t have them 1311 * hanging around in clients. Note that we want to do this after 1312 * initgroups, because at least on Solaris 2.3 it leaves file 1313 * descriptors open. 1314 */ 1315 for (i = 3; i < 64; i++) 1316 close(i); 1317 1318 /* 1319 * Must take new environment into use so that .ssh/rc, 1320 * /etc/ssh/sshrc and xauth are run in the proper environment. 1321 */ 1322 environ = env; 1323 1324#ifdef AFS 1325 /* Try to get AFS tokens for the local cell. */ 1326 if (k_hasafs()) { 1327 char cell[64]; 1328 1329 if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0) 1330 krb_afslog(cell, 0); 1331 1332 krb_afslog(0, 0); 1333 } 1334#endif /* AFS */ 1335 1336 /* Change current directory to the user\'s home directory. */ 1337 if (chdir(pw->pw_dir) < 0) { 1338 fprintf(stderr, "Could not chdir to home directory %s: %s\n", 1339 pw->pw_dir, strerror(errno)); 1340#ifdef HAVE_LOGIN_CAP 1341 if (login_getcapbool(lc, "requirehome", 0)) 1342 exit(1); 1343#endif 1344 } 1345 1346 if (!options.use_login) 1347 do_rc_files(s, shell); 1348 1349 /* restore SIGPIPE for child */ 1350 signal(SIGPIPE, SIG_DFL); 1351 1352 if (options.use_login) { 1353 launch_login(pw, hostname); 1354 /* NEVERREACHED */ 1355 } 1356 1357 /* Get the last component of the shell name. */ 1358 if ((shell0 = strrchr(shell, '/')) != NULL) 1359 shell0++; 1360 else 1361 shell0 = shell; 1362 1363 /* 1364 * If we have no command, execute the shell. In this case, the shell 1365 * name to be passed in argv[0] is preceded by '-' to indicate that 1366 * this is a login shell. 1367 */ 1368 if (!command) { 1369 char argv0[256]; 1370 1371 /* Start the shell. Set initial character to '-'. */ 1372 argv0[0] = '-'; 1373 1374 if (strlcpy(argv0 + 1, shell0, sizeof(argv0) - 1) 1375 >= sizeof(argv0) - 1) { 1376 errno = EINVAL; 1377 perror(shell); 1378 exit(1); 1379 } 1380 1381 /* Execute the shell. */ 1382 argv[0] = argv0; 1383 argv[1] = NULL; 1384 execve(shell, argv, env); 1385 1386 /* Executing the shell failed. */ 1387 perror(shell); 1388 exit(1); 1389 } 1390 /* 1391 * Execute the command using the user's shell. This uses the -c 1392 * option to execute the command. 1393 */ 1394 argv[0] = (char *) shell0; 1395 argv[1] = "-c"; 1396 argv[2] = (char *) command; 1397 argv[3] = NULL; 1398 execve(shell, argv, env); 1399 perror(shell); 1400 exit(1); 1401} 1402 1403Session * 1404session_new(void) 1405{ 1406 int i; 1407 static int did_init = 0; 1408 if (!did_init) { 1409 debug("session_new: init"); 1410 for (i = 0; i < MAX_SESSIONS; i++) { 1411 sessions[i].used = 0; 1412 } 1413 did_init = 1; 1414 } 1415 for (i = 0; i < MAX_SESSIONS; i++) { 1416 Session *s = &sessions[i]; 1417 if (! s->used) { 1418 memset(s, 0, sizeof(*s)); 1419 s->chanid = -1; 1420 s->ptyfd = -1; 1421 s->ttyfd = -1; 1422 s->used = 1; 1423 s->self = i; 1424 debug("session_new: session %d", i); 1425 return s; 1426 } 1427 } 1428 return NULL; 1429} 1430 1431static void 1432session_dump(void) 1433{ 1434 int i; 1435 for (i = 0; i < MAX_SESSIONS; i++) { 1436 Session *s = &sessions[i]; 1437 debug("dump: used %d session %d %p channel %d pid %ld", 1438 s->used, 1439 s->self, 1440 s, 1441 s->chanid, 1442 (long)s->pid); 1443 } 1444} 1445 1446int 1447session_open(Authctxt *authctxt, int chanid) 1448{ 1449 Session *s = session_new(); 1450 debug("session_open: channel %d", chanid); 1451 if (s == NULL) { 1452 error("no more sessions"); 1453 return 0; 1454 } 1455 s->authctxt = authctxt; 1456 s->pw = authctxt->pw; 1457 if (s->pw == NULL) 1458 fatal("no user for session %d", s->self); 1459 debug("session_open: session %d: link with channel %d", s->self, chanid); 1460 s->chanid = chanid; 1461 return 1; 1462} 1463 1464Session * 1465session_by_tty(char *tty) 1466{ 1467 int i; 1468 for (i = 0; i < MAX_SESSIONS; i++) { 1469 Session *s = &sessions[i]; 1470 if (s->used && s->ttyfd != -1 && strcmp(s->tty, tty) == 0) { 1471 debug("session_by_tty: session %d tty %s", i, tty); 1472 return s; 1473 } 1474 } 1475 debug("session_by_tty: unknown tty %.100s", tty); 1476 session_dump(); 1477 return NULL; 1478} 1479 1480static Session * 1481session_by_channel(int id) 1482{ 1483 int i; 1484 for (i = 0; i < MAX_SESSIONS; i++) { 1485 Session *s = &sessions[i]; 1486 if (s->used && s->chanid == id) { 1487 debug("session_by_channel: session %d channel %d", i, id); 1488 return s; 1489 } 1490 } 1491 debug("session_by_channel: unknown channel %d", id); 1492 session_dump(); 1493 return NULL; 1494} 1495 1496static Session * 1497session_by_pid(pid_t pid) 1498{ 1499 int i; 1500 debug("session_by_pid: pid %ld", (long)pid); 1501 for (i = 0; i < MAX_SESSIONS; i++) { 1502 Session *s = &sessions[i]; 1503 if (s->used && s->pid == pid) 1504 return s; 1505 } 1506 error("session_by_pid: unknown pid %ld", (long)pid); 1507 session_dump(); 1508 return NULL; 1509} 1510 1511static int 1512session_window_change_req(Session *s) 1513{ 1514 s->col = packet_get_int(); 1515 s->row = packet_get_int(); 1516 s->xpixel = packet_get_int(); 1517 s->ypixel = packet_get_int(); 1518 packet_check_eom(); 1519 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 1520 return 1; 1521} 1522 1523static int 1524session_pty_req(Session *s) 1525{ 1526 u_int len; 1527 int n_bytes; 1528 1529 if (no_pty_flag) { 1530 debug("Allocating a pty not permitted for this authentication."); 1531 return 0; 1532 } 1533 if (s->ttyfd != -1) { 1534 packet_disconnect("Protocol error: you already have a pty."); 1535 return 0; 1536 } 1537 /* Get the time and hostname when the user last logged in. */ 1538 if (options.print_lastlog) { 1539 s->hostname[0] = '\0'; 1540 s->last_login_time = get_last_login_time(s->pw->pw_uid, 1541 s->pw->pw_name, s->hostname, sizeof(s->hostname)); 1542 } 1543 1544 s->term = packet_get_string(&len); 1545 1546 if (compat20) { 1547 s->col = packet_get_int(); 1548 s->row = packet_get_int(); 1549 } else { 1550 s->row = packet_get_int(); 1551 s->col = packet_get_int(); 1552 } 1553 s->xpixel = packet_get_int(); 1554 s->ypixel = packet_get_int(); 1555 1556 if (strcmp(s->term, "") == 0) { 1557 xfree(s->term); 1558 s->term = NULL; 1559 } 1560 1561 /* Allocate a pty and open it. */ 1562 debug("Allocating pty."); 1563 if (!PRIVSEP(pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty)))) { 1564 if (s->term) 1565 xfree(s->term); 1566 s->term = NULL; 1567 s->ptyfd = -1; 1568 s->ttyfd = -1; 1569 error("session_pty_req: session %d alloc failed", s->self); 1570 return 0; 1571 } 1572 debug("session_pty_req: session %d alloc %s", s->self, s->tty); 1573 1574 /* for SSH1 the tty modes length is not given */ 1575 if (!compat20) 1576 n_bytes = packet_remaining(); 1577 tty_parse_modes(s->ttyfd, &n_bytes); 1578 1579 /* 1580 * Add a cleanup function to clear the utmp entry and record logout 1581 * time in case we call fatal() (e.g., the connection gets closed). 1582 */ 1583 fatal_add_cleanup(session_pty_cleanup, (void *)s); 1584 if (!use_privsep) 1585 pty_setowner(s->pw, s->tty); 1586 1587 /* Set window size from the packet. */ 1588 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 1589 1590 packet_check_eom(); 1591 session_proctitle(s); 1592 return 1; 1593} 1594 1595static int 1596session_subsystem_req(Session *s) 1597{ 1598 struct stat st; 1599 u_int len; 1600 int success = 0; 1601 char *cmd, *subsys = packet_get_string(&len); 1602 int i; 1603 1604 packet_check_eom(); 1605 log("subsystem request for %.100s", subsys); 1606 1607 for (i = 0; i < options.num_subsystems; i++) { 1608 if (strcmp(subsys, options.subsystem_name[i]) == 0) { 1609 cmd = options.subsystem_command[i]; 1610 if (stat(cmd, &st) < 0) { 1611 error("subsystem: cannot stat %s: %s", cmd, 1612 strerror(errno)); 1613 break; 1614 } 1615 debug("subsystem: exec() %s", cmd); 1616 s->is_subsystem = 1; 1617 do_exec(s, cmd); 1618 success = 1; 1619 break; 1620 } 1621 } 1622 1623 if (!success) 1624 log("subsystem request for %.100s failed, subsystem not found", 1625 subsys); 1626 1627 xfree(subsys); 1628 return success; 1629} 1630 1631static int 1632session_x11_req(Session *s) 1633{ 1634 int success; 1635 1636 s->single_connection = packet_get_char(); 1637 s->auth_proto = packet_get_string(NULL); 1638 s->auth_data = packet_get_string(NULL); 1639 s->screen = packet_get_int(); 1640 packet_check_eom(); 1641 1642 success = session_setup_x11fwd(s); 1643 if (!success) { 1644 xfree(s->auth_proto); 1645 xfree(s->auth_data); 1646 s->auth_proto = NULL; 1647 s->auth_data = NULL; 1648 } 1649 return success; 1650} 1651 1652static int 1653session_shell_req(Session *s) 1654{ 1655 packet_check_eom(); 1656 do_exec(s, NULL); 1657 return 1; 1658} 1659 1660static int 1661session_exec_req(Session *s) 1662{ 1663 u_int len; 1664 char *command = packet_get_string(&len); 1665 packet_check_eom(); 1666 do_exec(s, command); 1667 xfree(command); 1668 return 1; 1669} 1670 1671static int 1672session_auth_agent_req(Session *s) 1673{ 1674 static int called = 0; 1675 packet_check_eom(); 1676 if (no_agent_forwarding_flag) { 1677 debug("session_auth_agent_req: no_agent_forwarding_flag"); 1678 return 0; 1679 } 1680 if (called) { 1681 return 0; 1682 } else { 1683 called = 1; 1684 return auth_input_request_forwarding(s->pw); 1685 } 1686} 1687 1688int 1689session_input_channel_req(Channel *c, const char *rtype) 1690{ 1691 int success = 0; 1692 Session *s; 1693 1694 if ((s = session_by_channel(c->self)) == NULL) { 1695 log("session_input_channel_req: no session %d req %.100s", 1696 c->self, rtype); 1697 return 0; 1698 } 1699 debug("session_input_channel_req: session %d req %s", s->self, rtype); 1700 1701 /* 1702 * a session is in LARVAL state until a shell, a command 1703 * or a subsystem is executed 1704 */ 1705 if (c->type == SSH_CHANNEL_LARVAL) { 1706 if (strcmp(rtype, "shell") == 0) { 1707 success = session_shell_req(s); 1708 } else if (strcmp(rtype, "exec") == 0) { 1709 success = session_exec_req(s); 1710 } else if (strcmp(rtype, "pty-req") == 0) { 1711 success = session_pty_req(s); 1712 } else if (strcmp(rtype, "x11-req") == 0) { 1713 success = session_x11_req(s); 1714 } else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) { 1715 success = session_auth_agent_req(s); 1716 } else if (strcmp(rtype, "subsystem") == 0) { 1717 success = session_subsystem_req(s); 1718 } 1719 } 1720 if (strcmp(rtype, "window-change") == 0) { 1721 success = session_window_change_req(s); 1722 } 1723 return success; 1724} 1725 1726void 1727session_set_fds(Session *s, int fdin, int fdout, int fderr) 1728{ 1729 if (!compat20) 1730 fatal("session_set_fds: called for proto != 2.0"); 1731 /* 1732 * now that have a child and a pipe to the child, 1733 * we can activate our channel and register the fd's 1734 */ 1735 if (s->chanid == -1) 1736 fatal("no channel for session %d", s->self); 1737 channel_set_fds(s->chanid, 1738 fdout, fdin, fderr, 1739 fderr == -1 ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ, 1740 1, 1741 CHAN_SES_WINDOW_DEFAULT); 1742} 1743 1744/* 1745 * Function to perform pty cleanup. Also called if we get aborted abnormally 1746 * (e.g., due to a dropped connection). 1747 */ 1748void 1749session_pty_cleanup2(void *session) 1750{ 1751 Session *s = session; 1752 1753 if (s == NULL) { 1754 error("session_pty_cleanup: no session"); 1755 return; 1756 } 1757 if (s->ttyfd == -1) 1758 return; 1759 1760 debug("session_pty_cleanup: session %d release %s", s->self, s->tty); 1761 1762 /* Record that the user has logged out. */ 1763 if (s->pid != 0) 1764 record_logout(s->pid, s->tty, s->pw->pw_name); 1765 1766 /* Release the pseudo-tty. */ 1767 if (getuid() == 0) 1768 pty_release(s->tty); 1769 1770 /* 1771 * Close the server side of the socket pairs. We must do this after 1772 * the pty cleanup, so that another process doesn't get this pty 1773 * while we're still cleaning up. 1774 */ 1775 if (close(s->ptymaster) < 0) 1776 error("close(s->ptymaster/%d): %s", s->ptymaster, strerror(errno)); 1777 1778 /* unlink pty from session */ 1779 s->ttyfd = -1; 1780} 1781 1782void 1783session_pty_cleanup(void *session) 1784{ 1785 PRIVSEP(session_pty_cleanup2(session)); 1786} 1787 1788static void 1789session_exit_message(Session *s, int status) 1790{ 1791 Channel *c; 1792 1793 if ((c = channel_lookup(s->chanid)) == NULL) 1794 fatal("session_exit_message: session %d: no channel %d", 1795 s->self, s->chanid); 1796 debug("session_exit_message: session %d channel %d pid %ld", 1797 s->self, s->chanid, (long)s->pid); 1798 1799 if (WIFEXITED(status)) { 1800 channel_request_start(s->chanid, "exit-status", 0); 1801 packet_put_int(WEXITSTATUS(status)); 1802 packet_send(); 1803 } else if (WIFSIGNALED(status)) { 1804 channel_request_start(s->chanid, "exit-signal", 0); 1805 packet_put_int(WTERMSIG(status)); 1806#ifdef WCOREDUMP 1807 packet_put_char(WCOREDUMP(status)); 1808#else /* WCOREDUMP */ 1809 packet_put_char(0); 1810#endif /* WCOREDUMP */ 1811 packet_put_cstring(""); 1812 packet_put_cstring(""); 1813 packet_send(); 1814 } else { 1815 /* Some weird exit cause. Just exit. */ 1816 packet_disconnect("wait returned status %04x.", status); 1817 } 1818 1819 /* disconnect channel */ 1820 debug("session_exit_message: release channel %d", s->chanid); 1821 channel_cancel_cleanup(s->chanid); 1822 /* 1823 * emulate a write failure with 'chan_write_failed', nobody will be 1824 * interested in data we write. 1825 * Note that we must not call 'chan_read_failed', since there could 1826 * be some more data waiting in the pipe. 1827 */ 1828 if (c->ostate != CHAN_OUTPUT_CLOSED) 1829 chan_write_failed(c); 1830 s->chanid = -1; 1831} 1832 1833void 1834session_close(Session *s) 1835{ 1836 debug("session_close: session %d pid %ld", s->self, (long)s->pid); 1837 if (s->ttyfd != -1) { 1838 fatal_remove_cleanup(session_pty_cleanup, (void *)s); 1839 session_pty_cleanup(s); 1840 } 1841 if (s->term) 1842 xfree(s->term); 1843 if (s->display) 1844 xfree(s->display); 1845 if (s->auth_display) 1846 xfree(s->auth_display); 1847 if (s->auth_data) 1848 xfree(s->auth_data); 1849 if (s->auth_proto) 1850 xfree(s->auth_proto); 1851 s->used = 0; 1852 session_proctitle(s); 1853} 1854 1855void 1856session_close_by_pid(pid_t pid, int status) 1857{ 1858 Session *s = session_by_pid(pid); 1859 if (s == NULL) { 1860 debug("session_close_by_pid: no session for pid %ld", 1861 (long)pid); 1862 return; 1863 } 1864 if (s->chanid != -1) 1865 session_exit_message(s, status); 1866 session_close(s); 1867} 1868 1869/* 1870 * this is called when a channel dies before 1871 * the session 'child' itself dies 1872 */ 1873void 1874session_close_by_channel(int id, void *arg) 1875{ 1876 Session *s = session_by_channel(id); 1877 if (s == NULL) { 1878 debug("session_close_by_channel: no session for id %d", id); 1879 return; 1880 } 1881 debug("session_close_by_channel: channel %d child %ld", 1882 id, (long)s->pid); 1883 if (s->pid != 0) { 1884 debug("session_close_by_channel: channel %d: has child", id); 1885 /* 1886 * delay detach of session, but release pty, since 1887 * the fd's to the child are already closed 1888 */ 1889 if (s->ttyfd != -1) { 1890 fatal_remove_cleanup(session_pty_cleanup, (void *)s); 1891 session_pty_cleanup(s); 1892 } 1893 return; 1894 } 1895 /* detach by removing callback */ 1896 channel_cancel_cleanup(s->chanid); 1897 s->chanid = -1; 1898 session_close(s); 1899} 1900 1901void 1902session_destroy_all(void (*closefunc)(Session *)) 1903{ 1904 int i; 1905 for (i = 0; i < MAX_SESSIONS; i++) { 1906 Session *s = &sessions[i]; 1907 if (s->used) { 1908 if (closefunc != NULL) 1909 closefunc(s); 1910 else 1911 session_close(s); 1912 } 1913 } 1914} 1915 1916static char * 1917session_tty_list(void) 1918{ 1919 static char buf[1024]; 1920 int i; 1921 buf[0] = '\0'; 1922 for (i = 0; i < MAX_SESSIONS; i++) { 1923 Session *s = &sessions[i]; 1924 if (s->used && s->ttyfd != -1) { 1925 if (buf[0] != '\0') 1926 strlcat(buf, ",", sizeof buf); 1927 strlcat(buf, strrchr(s->tty, '/') + 1, sizeof buf); 1928 } 1929 } 1930 if (buf[0] == '\0') 1931 strlcpy(buf, "notty", sizeof buf); 1932 return buf; 1933} 1934 1935void 1936session_proctitle(Session *s) 1937{ 1938 if (s->pw == NULL) 1939 error("no user for session %d", s->self); 1940 else 1941 setproctitle("%s@%s", s->pw->pw_name, session_tty_list()); 1942} 1943 1944int 1945session_setup_x11fwd(Session *s) 1946{ 1947 struct stat st; 1948 char display[512], auth_display[512]; 1949 char hostname[MAXHOSTNAMELEN]; 1950 1951 if (no_x11_forwarding_flag) { 1952 packet_send_debug("X11 forwarding disabled in user configuration file."); 1953 return 0; 1954 } 1955 if (!options.x11_forwarding) { 1956 debug("X11 forwarding disabled in server configuration file."); 1957 return 0; 1958 } 1959 if (!options.xauth_location || 1960 (stat(options.xauth_location, &st) == -1)) { 1961 packet_send_debug("No xauth program; cannot forward with spoofing."); 1962 return 0; 1963 } 1964 if (options.use_login) { 1965 packet_send_debug("X11 forwarding disabled; " 1966 "not compatible with UseLogin=yes."); 1967 return 0; 1968 } 1969 if (s->display != NULL) { 1970 debug("X11 display already set."); 1971 return 0; 1972 } 1973 s->display_number = x11_create_display_inet(options.x11_display_offset, 1974 options.x11_use_localhost, s->single_connection); 1975 if (s->display_number == -1) { 1976 debug("x11_create_display_inet failed."); 1977 return 0; 1978 } 1979 1980 /* Set up a suitable value for the DISPLAY variable. */ 1981 if (gethostname(hostname, sizeof(hostname)) < 0) 1982 fatal("gethostname: %.100s", strerror(errno)); 1983 /* 1984 * auth_display must be used as the displayname when the 1985 * authorization entry is added with xauth(1). This will be 1986 * different than the DISPLAY string for localhost displays. 1987 */ 1988 if (options.x11_use_localhost) { 1989 snprintf(display, sizeof display, "localhost:%d.%d", 1990 s->display_number, s->screen); 1991 snprintf(auth_display, sizeof auth_display, "unix:%d.%d", 1992 s->display_number, s->screen); 1993 s->display = xstrdup(display); 1994 s->auth_display = xstrdup(auth_display); 1995 } else { 1996#ifdef IPADDR_IN_DISPLAY 1997 struct hostent *he; 1998 struct in_addr my_addr; 1999 2000 he = gethostbyname(hostname); 2001 if (he == NULL) { 2002 error("Can't get IP address for X11 DISPLAY."); 2003 packet_send_debug("Can't get IP address for X11 DISPLAY."); 2004 return 0; 2005 } 2006 memcpy(&my_addr, he->h_addr_list[0], sizeof(struct in_addr)); 2007 snprintf(display, sizeof display, "%.50s:%d.%d", inet_ntoa(my_addr), 2008 s->display_number, s->screen); 2009#else 2010 snprintf(display, sizeof display, "%.400s:%d.%d", hostname, 2011 s->display_number, s->screen); 2012#endif 2013 s->display = xstrdup(display); 2014 s->auth_display = xstrdup(display); 2015 } 2016 2017 return 1; 2018} 2019 2020static void 2021do_authenticated2(Authctxt *authctxt) 2022{ 2023 server_loop2(authctxt); 2024} 2025