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 * Copyright 2010 Sun Microsystems, Inc. All rights reserved. 36 * Use is subject to license terms. 37 */ 38 39 #include "includes.h" 40 RCSID("$OpenBSD: session.c,v 1.150 2002/09/16 19:55:33 stevesk Exp $"); 41 42 #ifdef HAVE_DEFOPEN 43 #include <deflt.h> 44 #include <ulimit.h> 45 #endif /* HAVE_DEFOPEN */ 46 47 #ifdef HAVE_LIBGEN_H 48 #include <libgen.h> 49 #endif 50 51 #include <priv.h> 52 53 #include "ssh.h" 54 #include "ssh1.h" 55 #include "ssh2.h" 56 #include "xmalloc.h" 57 #include "sshpty.h" 58 #include "packet.h" 59 #include "buffer.h" 60 #include "mpaux.h" 61 #include "uidswap.h" 62 #include "compat.h" 63 #include "channels.h" 64 #include "bufaux.h" 65 #include "auth.h" 66 #include "auth-options.h" 67 #include "pathnames.h" 68 #include "log.h" 69 #include "servconf.h" 70 #include "sshlogin.h" 71 #include "serverloop.h" 72 #include "canohost.h" 73 #include "session.h" 74 #include "tildexpand.h" 75 #include "misc.h" 76 #include "sftp.h" 77 78 #ifdef USE_PAM 79 #include <security/pam_appl.h> 80 #endif /* USE_PAM */ 81 82 #ifdef GSSAPI 83 #include "ssh-gss.h" 84 #endif 85 86 #ifdef ALTPRIVSEP 87 #include "altprivsep.h" 88 #endif /* ALTPRIVSEP */ 89 90 #ifdef HAVE_CYGWIN 91 #include <windows.h> 92 #include <sys/cygwin.h> 93 #define is_winnt (GetVersion() < 0x80000000) 94 #endif 95 96 /* func */ 97 98 Session *session_new(void); 99 void session_set_fds(Session *, int, int, int); 100 void session_pty_cleanup(void *); 101 void session_xauthfile_cleanup(void *s); 102 void session_proctitle(Session *); 103 int session_setup_x11fwd(Session *); 104 void do_exec_pty(Session *, const char *); 105 void do_exec_no_pty(Session *, const char *); 106 void do_exec(Session *, const char *); 107 void do_login(Session *, const char *); 108 void do_child(Session *, const char *); 109 void do_motd(void); 110 int check_quietlogin(Session *, const char *); 111 112 static void do_authenticated1(Authctxt *); 113 static void do_authenticated2(Authctxt *); 114 115 static int session_pty_req(Session *); 116 static int session_env_req(Session *s); 117 static void session_free_env(char ***envp); 118 static void safely_chroot(const char *path, uid_t uid); 119 static void drop_privs(uid_t uid); 120 121 #ifdef USE_PAM 122 static void session_do_pam(Session *, int); 123 #endif /* USE_PAM */ 124 125 /* import */ 126 extern ServerOptions options; 127 extern char *__progname; 128 extern int log_stderr; 129 extern int debug_flag; 130 extern u_int utmp_len; 131 extern void destroy_sensitive_data(void); 132 133 #ifdef GSSAPI 134 extern Gssctxt *xxx_gssctxt; 135 #endif /* GSSAPI */ 136 137 /* original command from peer. */ 138 const char *original_command = NULL; 139 140 /* data */ 141 #define MAX_SESSIONS 10 142 Session sessions[MAX_SESSIONS]; 143 144 #define SUBSYSTEM_NONE 0 145 #define SUBSYSTEM_EXT 1 146 #define SUBSYSTEM_INT_SFTP 2 147 148 #ifdef HAVE_LOGIN_CAP 149 login_cap_t *lc; 150 #endif 151 152 /* Name and directory of socket for authentication agent forwarding. */ 153 static char *auth_sock_name = NULL; 154 static char *auth_sock_dir = NULL; 155 156 /* removes the agent forwarding socket */ 157 158 static void 159 auth_sock_cleanup_proc(void *_pw) 160 { 161 struct passwd *pw = _pw; 162 163 if (auth_sock_name != NULL) { 164 temporarily_use_uid(pw); 165 unlink(auth_sock_name); 166 rmdir(auth_sock_dir); 167 auth_sock_name = NULL; 168 restore_uid(); 169 } 170 } 171 172 static int 173 auth_input_request_forwarding(struct passwd * pw) 174 { 175 Channel *nc; 176 int sock; 177 struct sockaddr_un sunaddr; 178 179 if (auth_sock_name != NULL) { 180 error("authentication forwarding requested twice."); 181 return 0; 182 } 183 184 /* Temporarily drop privileged uid for mkdir/bind. */ 185 temporarily_use_uid(pw); 186 187 /* Allocate a buffer for the socket name, and format the name. */ 188 auth_sock_name = xmalloc(MAXPATHLEN); 189 auth_sock_dir = xmalloc(MAXPATHLEN); 190 strlcpy(auth_sock_dir, "/tmp/ssh-XXXXXXXX", MAXPATHLEN); 191 192 /* Create private directory for socket */ 193 if (mkdtemp(auth_sock_dir) == NULL) { 194 packet_send_debug("Agent forwarding disabled: " 195 "mkdtemp() failed: %.100s", strerror(errno)); 196 restore_uid(); 197 xfree(auth_sock_name); 198 xfree(auth_sock_dir); 199 auth_sock_name = NULL; 200 auth_sock_dir = NULL; 201 return 0; 202 } 203 snprintf(auth_sock_name, MAXPATHLEN, "%s/agent.%ld", 204 auth_sock_dir, (long) getpid()); 205 206 /* delete agent socket on fatal() */ 207 fatal_add_cleanup(auth_sock_cleanup_proc, pw); 208 209 /* Create the socket. */ 210 sock = socket(AF_UNIX, SOCK_STREAM, 0); 211 if (sock < 0) 212 packet_disconnect("socket: %.100s", strerror(errno)); 213 214 /* Bind it to the name. */ 215 memset(&sunaddr, 0, sizeof(sunaddr)); 216 sunaddr.sun_family = AF_UNIX; 217 strlcpy(sunaddr.sun_path, auth_sock_name, sizeof(sunaddr.sun_path)); 218 219 if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) 220 packet_disconnect("bind: %.100s", strerror(errno)); 221 222 /* Restore the privileged uid. */ 223 restore_uid(); 224 225 /* Start listening on the socket. */ 226 if (listen(sock, 5) < 0) 227 packet_disconnect("listen: %.100s", strerror(errno)); 228 229 /* Allocate a channel for the authentication agent socket. */ 230 nc = channel_new("auth socket", 231 SSH_CHANNEL_AUTH_SOCKET, sock, sock, -1, 232 CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 233 0, xstrdup("auth socket"), 1); 234 strlcpy(nc->path, auth_sock_name, sizeof(nc->path)); 235 return 1; 236 } 237 238 239 void 240 do_authenticated(Authctxt *authctxt) 241 { 242 /* setup the channel layer */ 243 if (!no_port_forwarding_flag && options.allow_tcp_forwarding) 244 channel_permit_all_opens(); 245 246 if (compat20) 247 do_authenticated2(authctxt); 248 else 249 do_authenticated1(authctxt); 250 251 /* remove agent socket */ 252 if (auth_sock_name != NULL) 253 auth_sock_cleanup_proc(authctxt->pw); 254 #ifdef KRB4 255 if (options.kerberos_ticket_cleanup) 256 krb4_cleanup_proc(authctxt); 257 #endif 258 #ifdef KRB5 259 if (options.kerberos_ticket_cleanup) 260 krb5_cleanup_proc(authctxt); 261 #endif 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 */ 270 static void 271 do_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 s->authctxt = authctxt; 281 s->pw = authctxt->pw; 282 283 /* 284 * We stay in this loop until the client requests to execute a shell 285 * or a command. 286 */ 287 for (;;) { 288 success = 0; 289 290 /* Get a packet from the client. */ 291 type = packet_read(); 292 293 /* Process the packet. */ 294 switch (type) { 295 case SSH_CMSG_REQUEST_COMPRESSION: 296 compression_level = packet_get_int(); 297 packet_check_eom(); 298 if (compression_level < 1 || compression_level > 9) { 299 packet_send_debug("Received illegal compression level %d.", 300 compression_level); 301 break; 302 } 303 if (!options.compression) { 304 debug2("compression disabled"); 305 break; 306 } 307 /* Enable compression after we have responded with SUCCESS. */ 308 enable_compression_after_reply = 1; 309 success = 1; 310 break; 311 312 case SSH_CMSG_REQUEST_PTY: 313 success = session_pty_req(s); 314 break; 315 316 case SSH_CMSG_X11_REQUEST_FORWARDING: 317 s->auth_proto = packet_get_string(&proto_len); 318 s->auth_data = packet_get_string(&data_len); 319 320 screen_flag = packet_get_protocol_flags() & 321 SSH_PROTOFLAG_SCREEN_NUMBER; 322 debug2("SSH_PROTOFLAG_SCREEN_NUMBER: %d", screen_flag); 323 324 if (packet_remaining() == 4) { 325 if (!screen_flag) 326 debug2("Buggy client: " 327 "X11 screen flag missing"); 328 s->screen = packet_get_int(); 329 } else { 330 s->screen = 0; 331 } 332 packet_check_eom(); 333 success = session_setup_x11fwd(s); 334 if (!success) { 335 xfree(s->auth_proto); 336 xfree(s->auth_data); 337 s->auth_proto = NULL; 338 s->auth_data = NULL; 339 } 340 break; 341 342 case SSH_CMSG_AGENT_REQUEST_FORWARDING: 343 if (no_agent_forwarding_flag || compat13) { 344 debug("Authentication agent forwarding not permitted for this authentication."); 345 break; 346 } 347 debug("Received authentication agent forwarding request."); 348 success = auth_input_request_forwarding(s->pw); 349 break; 350 351 case SSH_CMSG_PORT_FORWARD_REQUEST: 352 if (no_port_forwarding_flag) { 353 debug("Port forwarding not permitted for this authentication."); 354 break; 355 } 356 if (!options.allow_tcp_forwarding) { 357 debug("Port forwarding not permitted."); 358 break; 359 } 360 debug("Received TCP/IP port forwarding request."); 361 channel_input_port_forward_request(s->pw->pw_uid == 0, options.gateway_ports); 362 success = 1; 363 break; 364 365 case SSH_CMSG_MAX_PACKET_SIZE: 366 if (packet_set_maxsize(packet_get_int()) > 0) 367 success = 1; 368 break; 369 370 #if defined(AFS) || defined(KRB5) 371 case SSH_CMSG_HAVE_KERBEROS_TGT: 372 if (!options.kerberos_tgt_passing) { 373 verbose("Kerberos TGT passing disabled."); 374 } else { 375 char *kdata = packet_get_string(&dlen); 376 packet_check_eom(); 377 378 /* XXX - 0x41, see creds_to_radix version */ 379 if (kdata[0] != 0x41) { 380 #ifdef KRB5 381 krb5_data tgt; 382 tgt.data = kdata; 383 tgt.length = dlen; 384 385 if (auth_krb5_tgt(s->authctxt, &tgt)) 386 success = 1; 387 else 388 verbose("Kerberos v5 TGT refused for %.100s", s->authctxt->user); 389 #endif /* KRB5 */ 390 } else { 391 #ifdef AFS 392 if (auth_krb4_tgt(s->authctxt, kdata)) 393 success = 1; 394 else 395 verbose("Kerberos v4 TGT refused for %.100s", s->authctxt->user); 396 #endif /* AFS */ 397 } 398 xfree(kdata); 399 } 400 break; 401 #endif /* AFS || KRB5 */ 402 403 #ifdef AFS 404 case SSH_CMSG_HAVE_AFS_TOKEN: 405 if (!options.afs_token_passing || !k_hasafs()) { 406 verbose("AFS token passing disabled."); 407 } else { 408 /* Accept AFS token. */ 409 char *token = packet_get_string(&dlen); 410 packet_check_eom(); 411 412 if (auth_afs_token(s->authctxt, token)) 413 success = 1; 414 else 415 verbose("AFS token refused for %.100s", 416 s->authctxt->user); 417 xfree(token); 418 } 419 break; 420 #endif /* AFS */ 421 422 case SSH_CMSG_EXEC_SHELL: 423 case SSH_CMSG_EXEC_CMD: 424 if (type == SSH_CMSG_EXEC_CMD) { 425 command = packet_get_string(&dlen); 426 debug("Exec command '%.500s'", command); 427 do_exec(s, command); 428 xfree(command); 429 } else { 430 do_exec(s, NULL); 431 } 432 packet_check_eom(); 433 session_close(s); 434 return; 435 436 default: 437 /* 438 * Any unknown messages in this phase are ignored, 439 * and a failure message is returned. 440 */ 441 log("Unknown packet type received after authentication: %d", type); 442 } 443 packet_start(success ? SSH_SMSG_SUCCESS : SSH_SMSG_FAILURE); 444 packet_send(); 445 packet_write_wait(); 446 447 /* Enable compression now that we have replied if appropriate. */ 448 if (enable_compression_after_reply) { 449 enable_compression_after_reply = 0; 450 packet_start_compression(compression_level); 451 } 452 } 453 } 454 455 /* 456 * This is called to fork and execute a command when we have no tty. This 457 * will call do_child from the child, and server_loop from the parent after 458 * setting up file descriptors and such. 459 */ 460 void 461 do_exec_no_pty(Session *s, const char *command) 462 { 463 pid_t pid; 464 465 int inout[2], err[2]; 466 /* Uses socket pairs to communicate with the program. */ 467 if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) < 0 || 468 socketpair(AF_UNIX, SOCK_STREAM, 0, err) < 0) 469 packet_disconnect("Could not create socket pairs: %.100s", 470 strerror(errno)); 471 if (s == NULL) 472 fatal("do_exec_no_pty: no session"); 473 474 session_proctitle(s); 475 476 /* Fork the child. */ 477 if ((pid = fork()) == 0) { 478 fatal_remove_all_cleanups(); 479 480 /* Child. Reinitialize the log since the pid has changed. */ 481 log_init(__progname, options.log_level, options.log_facility, log_stderr); 482 483 /* 484 * Create a new session and process group since the 4.4BSD 485 * setlogin() affects the entire process group. 486 */ 487 if (setsid() < 0) 488 error("setsid failed: %.100s", strerror(errno)); 489 490 /* 491 * Redirect stdin, stdout, and stderr. Stdin and stdout will 492 * use the same socket, as some programs (particularly rdist) 493 * seem to depend on it. 494 */ 495 close(inout[1]); 496 close(err[1]); 497 if (dup2(inout[0], 0) < 0) /* stdin */ 498 perror("dup2 stdin"); 499 if (dup2(inout[0], 1) < 0) /* stdout. Note: same socket as stdin. */ 500 perror("dup2 stdout"); 501 if (s->is_subsystem) { 502 /* 503 * Redirect the subsystem's stderr to /dev/null. We might send it 504 * over to the other side but changing that might break existing 505 * SSH clients. 506 */ 507 close(err[0]); 508 if ((err[0] = open(_PATH_DEVNULL, O_WRONLY)) == -1) 509 fatal("Cannot open /dev/null: %.100s", strerror(errno)); 510 } 511 if (dup2(err[0], 2) < 0) /* stderr */ 512 perror("dup2 stderr"); 513 514 #ifdef _UNICOS 515 cray_init_job(s->pw); /* set up cray jid and tmpdir */ 516 #endif 517 518 /* Do processing for the child (exec command etc). */ 519 do_child(s, command); 520 /* NOTREACHED */ 521 } 522 #ifdef _UNICOS 523 signal(WJSIGNAL, cray_job_termination_handler); 524 #endif /* _UNICOS */ 525 #ifdef HAVE_CYGWIN 526 if (is_winnt) 527 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); 528 #endif 529 if (pid < 0) 530 packet_disconnect("fork failed: %.100s", strerror(errno)); 531 532 s->pid = pid; 533 /* Set interactive/non-interactive mode. */ 534 packet_set_interactive(s->display != NULL); 535 536 /* We are the parent. Close the child sides of the socket pairs. */ 537 close(inout[0]); 538 close(err[0]); 539 540 /* 541 * Enter the interactive session. Note: server_loop must be able to 542 * handle the case that fdin and fdout are the same. 543 */ 544 if (compat20) { 545 session_set_fds(s, inout[1], inout[1], s->is_subsystem ? -1 : err[1]); 546 if (s->is_subsystem) 547 close(err[1]); 548 /* Don't close channel before sending exit-status! */ 549 channel_set_wait_for_exit(s->chanid, 1); 550 } else { 551 server_loop(pid, inout[1], inout[1], err[1]); 552 /* server_loop has closed inout[1] and err[1]. */ 553 } 554 } 555 556 /* 557 * This is called to fork and execute a command when we have a tty. This 558 * will call do_child from the child, and server_loop from the parent after 559 * setting up file descriptors, controlling tty, updating wtmp, utmp, 560 * lastlog, and other such operations. 561 */ 562 void 563 do_exec_pty(Session *s, const char *command) 564 { 565 int fdout, ptyfd, ttyfd, ptymaster, pipe_fds[2]; 566 pid_t pid; 567 568 if (s == NULL) 569 fatal("do_exec_pty: no session"); 570 ptyfd = s->ptyfd; 571 ttyfd = s->ttyfd; 572 573 #ifdef USE_PAM 574 session_do_pam(s, 1); /* pam_open_session() */ 575 #endif /* USE_PAM */ 576 577 /* 578 * This pipe lets sshd wait for child to exec or exit. This is 579 * particularly important for ALTPRIVSEP because the child is 580 * the one to call the monitor to request a record_login() and 581 * we don't want the child and the parent to compete for the 582 * monitor's attention. But this is generic code and doesn't 583 * hurt to have here even if ALTPRIVSEP is not used. 584 */ 585 if (pipe(pipe_fds) != 0) 586 packet_disconnect("pipe failed: %.100s", strerror(errno)); 587 588 (void) fcntl(pipe_fds[0], F_SETFD, FD_CLOEXEC); 589 (void) fcntl(pipe_fds[1], F_SETFD, FD_CLOEXEC); 590 591 /* Fork the child. */ 592 if ((pid = fork()) == 0) { 593 (void) close(pipe_fds[0]); 594 595 fatal_remove_all_cleanups(); 596 597 /* Child. Reinitialize the log because the pid has changed. */ 598 log_init(__progname, options.log_level, options.log_facility, log_stderr); 599 /* Close the master side of the pseudo tty. */ 600 close(ptyfd); 601 602 /* Make the pseudo tty our controlling tty. */ 603 pty_make_controlling_tty(&ttyfd, s->tty); 604 605 /* Redirect stdin/stdout/stderr from the pseudo tty. */ 606 if (dup2(ttyfd, 0) < 0) 607 error("dup2 stdin: %s", strerror(errno)); 608 if (dup2(ttyfd, 1) < 0) 609 error("dup2 stdout: %s", strerror(errno)); 610 if (dup2(ttyfd, 2) < 0) 611 error("dup2 stderr: %s", strerror(errno)); 612 613 /* Close the extra descriptor for the pseudo tty. */ 614 close(ttyfd); 615 616 /* record login, etc. similar to login(1) */ 617 do_login(s, command); 618 619 /* 620 * Close the pipe to the parent so it can re-enter its event 621 * loop and service the ptm; if enough debug messages get 622 * written to the pty before this happens there will be a 623 * deadlock. 624 */ 625 close(pipe_fds[1]); 626 627 /* 628 * do_motd() was called originally in do_login(). However, 629 * when the /etc/motd file is large, a deadlock would happen, 630 * because 631 * - The child is blocked at fputs() to pty, when pty buffer 632 * is full. 633 * - The parent can not consume the pty buffer, because it is 634 * still blocked at read(pipe_fds[0]). 635 * 636 * To resolve the deadlock issue, we defer do_motd() after 637 * close(pipe_fds[1]). 638 */ 639 do_motd(); 640 641 /* Do common processing for the child, such as execing the command. */ 642 do_child(s, command); 643 /* NOTREACHED */ 644 } 645 646 /* Wait for child to exec() or exit() */ 647 (void) close(pipe_fds[1]); 648 (void) read(pipe_fds[0], &pipe_fds[1], sizeof(int)); 649 650 #ifdef _UNICOS 651 signal(WJSIGNAL, cray_job_termination_handler); 652 #endif /* _UNICOS */ 653 #ifdef HAVE_CYGWIN 654 if (is_winnt) 655 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); 656 #endif 657 if (pid < 0) 658 packet_disconnect("fork failed: %.100s", strerror(errno)); 659 s->pid = pid; 660 661 /* Parent. Close the slave side of the pseudo tty. */ 662 close(ttyfd); 663 664 /* 665 * Create another descriptor of the pty master side for use as the 666 * standard input. We could use the original descriptor, but this 667 * simplifies code in server_loop. The descriptor is bidirectional. 668 */ 669 fdout = dup(ptyfd); 670 if (fdout < 0) 671 packet_disconnect("dup #1 failed: %.100s", strerror(errno)); 672 673 /* we keep a reference to the pty master */ 674 ptymaster = dup(ptyfd); 675 if (ptymaster < 0) 676 packet_disconnect("dup #2 failed: %.100s", strerror(errno)); 677 s->ptymaster = ptymaster; 678 679 /* Enter interactive session. */ 680 packet_set_interactive(1); 681 if (compat20) { 682 session_set_fds(s, ptyfd, fdout, -1); 683 /* Don't close channel before sending exit-status! */ 684 channel_set_wait_for_exit(s->chanid, 1); 685 } else { 686 server_loop(pid, ptyfd, fdout, -1); 687 /* server_loop _has_ closed ptyfd and fdout. */ 688 } 689 } 690 691 /* 692 * This is called to fork and execute a command. If another command is 693 * to be forced, execute that instead. 694 */ 695 void 696 do_exec(Session *s, const char *command) 697 { 698 if (command) 699 s->command = xstrdup(command); 700 701 if (forced_command) { 702 original_command = command; 703 command = forced_command; 704 debug("Forced command '%.900s'", command); 705 } 706 707 if (s->ttyfd != -1) 708 do_exec_pty(s, command); 709 else 710 do_exec_no_pty(s, command); 711 712 original_command = NULL; 713 } 714 715 716 /* administrative, login(1)-like work */ 717 void 718 do_login(Session *s, const char *command) 719 { 720 #ifndef ALTPRIVSEP 721 struct passwd * pw = s->pw; 722 #endif /* ALTPRIVSEP*/ 723 pid_t pid = getpid(); 724 725 /* Record that there was a login on that tty from the remote host. */ 726 #ifdef ALTPRIVSEP 727 debug3("Recording SSHv2 channel login in utmpx/wtmpx"); 728 altprivsep_record_login(pid, s->tty); 729 #endif /* ALTPRIVSEP*/ 730 731 if (check_quietlogin(s, command)) 732 return; 733 734 #ifdef USE_PAM 735 print_pam_messages(); 736 #endif /* USE_PAM */ 737 #ifdef WITH_AIXAUTHENTICATE 738 if (aixloginmsg && *aixloginmsg) 739 printf("%s\n", aixloginmsg); 740 #endif /* WITH_AIXAUTHENTICATE */ 741 } 742 743 /* 744 * Display the message of the day. 745 */ 746 void 747 do_motd(void) 748 { 749 FILE *f; 750 char buf[256]; 751 752 if (options.print_motd) { 753 #ifdef HAVE_LOGIN_CAP 754 f = fopen(login_getcapstr(lc, "welcome", "/etc/motd", 755 "/etc/motd"), "r"); 756 #else 757 f = fopen("/etc/motd", "r"); 758 #endif 759 if (f) { 760 while (fgets(buf, sizeof(buf), f)) 761 fputs(buf, stdout); 762 fclose(f); 763 } 764 } 765 } 766 767 768 /* 769 * Check for quiet login, either .hushlogin or command given. 770 */ 771 int 772 check_quietlogin(Session *s, const char *command) 773 { 774 char buf[256]; 775 struct passwd *pw = s->pw; 776 struct stat st; 777 778 /* Return 1 if .hushlogin exists or a command given. */ 779 if (command != NULL) 780 return 1; 781 snprintf(buf, sizeof(buf), "%.200s/.hushlogin", pw->pw_dir); 782 #ifdef HAVE_LOGIN_CAP 783 if (login_getcapbool(lc, "hushlogin", 0) || stat(buf, &st) >= 0) 784 return 1; 785 #else 786 if (stat(buf, &st) >= 0) 787 return 1; 788 #endif 789 return 0; 790 } 791 792 /* 793 * Sets the value of the given variable in the environment. If the variable 794 * already exists, its value is overriden. 795 */ 796 void 797 child_set_env(char ***envp, u_int *envsizep, const char *name, 798 const char *value) 799 { 800 debug3("child_set_env(%s, %s)", name, value); 801 child_set_env_silent(envp, envsizep, name, value); 802 } 803 804 805 void 806 child_set_env_silent(char ***envp, u_int *envsizep, const char *name, 807 const char *value) 808 { 809 u_int i, namelen; 810 char **env; 811 812 /* 813 * Find the slot where the value should be stored. If the variable 814 * already exists, we reuse the slot; otherwise we append a new slot 815 * at the end of the array, expanding if necessary. 816 */ 817 env = *envp; 818 namelen = strlen(name); 819 for (i = 0; env[i]; i++) 820 if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=') 821 break; 822 if (env[i]) { 823 /* Reuse the slot. */ 824 xfree(env[i]); 825 } else { 826 /* New variable. Expand if necessary. */ 827 if (i >= (*envsizep) - 1) { 828 if (*envsizep >= 1000) 829 fatal("child_set_env: too many env vars," 830 " skipping: %.100s", name); 831 (*envsizep) += 50; 832 env = (*envp) = xrealloc(env, (*envsizep) * sizeof(char *)); 833 } 834 /* Need to set the NULL pointer at end of array beyond the new slot. */ 835 env[i + 1] = NULL; 836 } 837 838 /* Allocate space and format the variable in the appropriate slot. */ 839 env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1); 840 snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value); 841 } 842 843 /* 844 * Reads environment variables from the given file and adds/overrides them 845 * into the environment. If the file does not exist, this does nothing. 846 * Otherwise, it must consist of empty lines, comments (line starts with '#') 847 * and assignments of the form name=value. No other forms are allowed. 848 */ 849 static void 850 read_environment_file(char ***env, u_int *envsize, 851 const char *filename) 852 { 853 FILE *f; 854 char buf[4096]; 855 char *cp, *value; 856 u_int lineno = 0; 857 858 f = fopen(filename, "r"); 859 if (!f) 860 return; 861 862 while (fgets(buf, sizeof(buf), f)) { 863 if (++lineno > 1000) 864 fatal("Too many lines in environment file %s", filename); 865 for (cp = buf; *cp == ' ' || *cp == '\t'; cp++) 866 ; 867 if (!*cp || *cp == '#' || *cp == '\n') 868 continue; 869 if (strchr(cp, '\n')) 870 *strchr(cp, '\n') = '\0'; 871 value = strchr(cp, '='); 872 if (value == NULL) { 873 fprintf(stderr, gettext("Bad line %u in %.100s\n"), 874 lineno, filename); 875 continue; 876 } 877 /* 878 * Replace the equals sign by nul, and advance value to 879 * the value string. 880 */ 881 *value = '\0'; 882 value++; 883 child_set_env(env, envsize, cp, value); 884 } 885 fclose(f); 886 } 887 888 void copy_environment(char **source, char ***env, u_int *envsize) 889 { 890 char *var_name, *var_val; 891 int i; 892 893 if (source == NULL) 894 return; 895 896 for(i = 0; source[i] != NULL; i++) { 897 var_name = xstrdup(source[i]); 898 if ((var_val = strstr(var_name, "=")) == NULL) { 899 xfree(var_name); 900 continue; 901 } 902 *var_val++ = '\0'; 903 904 debug3("Copy environment: %s=%s", var_name, var_val); 905 child_set_env(env, envsize, var_name, var_val); 906 907 xfree(var_name); 908 } 909 } 910 911 #ifdef HAVE_DEFOPEN 912 static 913 void 914 deflt_do_setup_env(Session *s, const char *shell, char ***env, u_int *envsize) 915 { 916 int flags; 917 char *ptr; 918 mode_t Umask = 022; 919 920 if (defopen(_PATH_DEFAULT_LOGIN)) 921 return; 922 923 /* Ignore case */ 924 flags = defcntl(DC_GETFLAGS, 0); 925 TURNOFF(flags, DC_CASE); 926 (void) defcntl(DC_SETFLAGS, flags); 927 928 /* TZ & HZ */ 929 if ((ptr = defread("TIMEZONE=")) != NULL) 930 child_set_env(env, envsize, "TZ", ptr); 931 if ((ptr = defread("HZ=")) != NULL) 932 child_set_env(env, envsize, "HZ", ptr); 933 934 /* PATH */ 935 if (s->pw->pw_uid != 0 && (ptr = defread("PATH=")) != NULL) 936 child_set_env(env, envsize, "PATH", ptr); 937 if (s->pw->pw_uid == 0 && (ptr = defread("SUPATH=")) != NULL) 938 child_set_env(env, envsize, "PATH", ptr); 939 940 /* SHELL */ 941 if ((ptr = defread("ALTSHELL=")) != NULL) { 942 if (strcasecmp("YES", ptr) == 0) 943 child_set_env(env, envsize, "SHELL", shell); 944 else 945 child_set_env(env, envsize, "SHELL", ""); 946 } 947 948 /* UMASK */ 949 if ((ptr = defread("UMASK=")) != NULL && 950 sscanf(ptr, "%lo", &Umask) == 1 && 951 Umask <= (mode_t)0777) 952 (void) umask(Umask); 953 else 954 (void) umask(022); 955 956 /* ULIMIT */ 957 if ((ptr = defread("ULIMIT=")) != NULL && atol(ptr) > 0L && 958 ulimit(UL_SETFSIZE, atol(ptr)) < 0L) 959 error("Could not set ULIMIT to %ld from %s\n", atol(ptr), 960 _PATH_DEFAULT_LOGIN); 961 962 (void) defopen(NULL); 963 } 964 #endif /* HAVE_DEFOPEN */ 965 966 static char ** 967 do_setup_env(Session *s, const char *shell) 968 { 969 char buf[256]; 970 char path_maildir[] = _PATH_MAILDIR; 971 u_int i, envsize, pm_len; 972 char **env; 973 struct passwd *pw = s->pw; 974 975 /* Initialize the environment. */ 976 envsize = 100; 977 env = xmalloc(envsize * sizeof(char *)); 978 env[0] = NULL; 979 980 #ifdef HAVE_CYGWIN 981 /* 982 * The Windows environment contains some setting which are 983 * important for a running system. They must not be dropped. 984 */ 985 copy_environment(environ, &env, &envsize); 986 #endif 987 988 #ifdef GSSAPI 989 /* Allow any GSSAPI methods that we've used to alter 990 * the childs environment as they see fit 991 */ 992 ssh_gssapi_do_child(xxx_gssctxt, &env,&envsize); 993 #endif 994 995 /* Set basic environment. */ 996 child_set_env(&env, &envsize, "USER", pw->pw_name); 997 child_set_env(&env, &envsize, "LOGNAME", pw->pw_name); 998 child_set_env(&env, &envsize, "HOME", pw->pw_dir); 999 #ifdef HAVE_LOGIN_CAP 1000 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETPATH) < 0) 1001 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); 1002 else 1003 child_set_env(&env, &envsize, "PATH", getenv("PATH")); 1004 #else /* HAVE_LOGIN_CAP */ 1005 # ifndef HAVE_CYGWIN 1006 /* 1007 * There's no standard path on Windows. The path contains 1008 * important components pointing to the system directories, 1009 * needed for loading shared libraries. So the path better 1010 * remains intact here. 1011 */ 1012 # ifdef SUPERUSER_PATH 1013 child_set_env(&env, &envsize, "PATH", 1014 s->pw->pw_uid == 0 ? SUPERUSER_PATH : _PATH_STDPATH); 1015 # else 1016 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); 1017 # endif /* SUPERUSER_PATH */ 1018 # endif /* HAVE_CYGWIN */ 1019 #endif /* HAVE_LOGIN_CAP */ 1020 1021 pm_len = strlen(path_maildir); 1022 if (path_maildir[pm_len - 1] == '/' && pm_len > 1) 1023 path_maildir[pm_len - 1] = NULL; 1024 snprintf(buf, sizeof buf, "%.200s/%.50s", 1025 path_maildir, pw->pw_name); 1026 child_set_env(&env, &envsize, "MAIL", buf); 1027 1028 /* Normal systems set SHELL by default. */ 1029 child_set_env(&env, &envsize, "SHELL", shell); 1030 1031 #ifdef HAVE_DEFOPEN 1032 deflt_do_setup_env(s, shell, &env, &envsize); 1033 #endif /* HAVE_DEFOPEN */ 1034 1035 #define PASS_ENV(x) \ 1036 if (getenv(x)) \ 1037 child_set_env(&env, &envsize, x, getenv(x)); 1038 1039 if (getenv("TZ")) 1040 child_set_env(&env, &envsize, "TZ", getenv("TZ")); 1041 1042 if (s->auth_file != NULL) 1043 child_set_env(&env, &envsize, "XAUTHORITY", s->auth_file); 1044 1045 PASS_ENV("LANG") 1046 PASS_ENV("LC_ALL") 1047 PASS_ENV("LC_CTYPE") 1048 PASS_ENV("LC_COLLATE") 1049 PASS_ENV("LC_TIME") 1050 PASS_ENV("LC_NUMERIC") 1051 PASS_ENV("LC_MONETARY") 1052 PASS_ENV("LC_MESSAGES") 1053 1054 #undef PASS_ENV 1055 1056 if (s->env != NULL) 1057 copy_environment(s->env, &env, &envsize); 1058 1059 /* Set custom environment options from RSA authentication. */ 1060 while (custom_environment) { 1061 struct envstring *ce = custom_environment; 1062 char *str = ce->s; 1063 1064 for (i = 0; str[i] != '=' && str[i]; i++) 1065 ; 1066 if (str[i] == '=') { 1067 str[i] = 0; 1068 child_set_env(&env, &envsize, str, str + i + 1); 1069 } 1070 custom_environment = ce->next; 1071 xfree(ce->s); 1072 xfree(ce); 1073 } 1074 1075 /* SSH_CLIENT deprecated */ 1076 snprintf(buf, sizeof buf, "%.50s %d %d", 1077 get_remote_ipaddr(), get_remote_port(), get_local_port()); 1078 child_set_env(&env, &envsize, "SSH_CLIENT", buf); 1079 1080 snprintf(buf, sizeof buf, "%.50s %d %.50s %d", 1081 get_remote_ipaddr(), get_remote_port(), 1082 get_local_ipaddr(packet_get_connection_in()), get_local_port()); 1083 child_set_env(&env, &envsize, "SSH_CONNECTION", buf); 1084 1085 if (s->ttyfd != -1) 1086 child_set_env(&env, &envsize, "SSH_TTY", s->tty); 1087 if (s->term) 1088 child_set_env(&env, &envsize, "TERM", s->term); 1089 if (s->display) 1090 child_set_env(&env, &envsize, "DISPLAY", s->display); 1091 if (original_command) 1092 child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND", 1093 original_command); 1094 1095 #ifdef _UNICOS 1096 if (cray_tmpdir[0] != '\0') 1097 child_set_env(&env, &envsize, "TMPDIR", cray_tmpdir); 1098 #endif /* _UNICOS */ 1099 1100 #ifdef _AIX 1101 { 1102 char *cp; 1103 1104 if ((cp = getenv("AUTHSTATE")) != NULL) 1105 child_set_env(&env, &envsize, "AUTHSTATE", cp); 1106 if ((cp = getenv("KRB5CCNAME")) != NULL) 1107 child_set_env(&env, &envsize, "KRB5CCNAME", cp); 1108 read_environment_file(&env, &envsize, "/etc/environment"); 1109 } 1110 #endif 1111 #ifdef KRB4 1112 if (s->authctxt->krb4_ticket_file) 1113 child_set_env(&env, &envsize, "KRBTKFILE", 1114 s->authctxt->krb4_ticket_file); 1115 #endif 1116 #ifdef KRB5 1117 if (s->authctxt->krb5_ticket_file) 1118 child_set_env(&env, &envsize, "KRB5CCNAME", 1119 s->authctxt->krb5_ticket_file); 1120 #endif 1121 #ifdef USE_PAM 1122 /* 1123 * Pull in any environment variables that may have 1124 * been set by PAM. 1125 */ 1126 { 1127 char **p; 1128 1129 p = fetch_pam_environment(s->authctxt); 1130 copy_environment(p, &env, &envsize); 1131 free_pam_environment(p); 1132 } 1133 #endif /* USE_PAM */ 1134 1135 if (auth_sock_name != NULL) 1136 child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME, 1137 auth_sock_name); 1138 1139 /* read $HOME/.ssh/environment. */ 1140 if (options.permit_user_env) { 1141 snprintf(buf, sizeof buf, "%.200s/.ssh/environment", 1142 strcmp(pw->pw_dir, "/") ? pw->pw_dir : ""); 1143 read_environment_file(&env, &envsize, buf); 1144 } 1145 if (debug_flag) { 1146 /* dump the environment */ 1147 fprintf(stderr, gettext("Environment:\n")); 1148 for (i = 0; env[i]; i++) 1149 fprintf(stderr, " %.200s\n", env[i]); 1150 } 1151 return env; 1152 } 1153 1154 /* 1155 * Run $HOME/.ssh/rc, /etc/ssh/sshrc, or xauth (whichever is found 1156 * first in this order). 1157 */ 1158 static void 1159 do_rc_files(Session *s, const char *shell) 1160 { 1161 FILE *f = NULL; 1162 char cmd[1024]; 1163 int do_xauth; 1164 struct stat st; 1165 1166 do_xauth = 1167 s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL; 1168 1169 /* ignore _PATH_SSH_USER_RC for subsystems */ 1170 if (!s->is_subsystem && (stat(_PATH_SSH_USER_RC, &st) >= 0)) { 1171 snprintf(cmd, sizeof cmd, "%s -c '%s %s'", 1172 shell, _PATH_BSHELL, _PATH_SSH_USER_RC); 1173 if (debug_flag) 1174 fprintf(stderr, "Running %s\n", cmd); 1175 f = popen(cmd, "w"); 1176 if (f) { 1177 if (do_xauth) 1178 fprintf(f, "%s %s\n", s->auth_proto, 1179 s->auth_data); 1180 pclose(f); 1181 } else 1182 fprintf(stderr, "Could not run %s\n", 1183 _PATH_SSH_USER_RC); 1184 } else if (stat(_PATH_SSH_SYSTEM_RC, &st) >= 0) { 1185 if (debug_flag) 1186 fprintf(stderr, "Running %s %s\n", _PATH_BSHELL, 1187 _PATH_SSH_SYSTEM_RC); 1188 f = popen(_PATH_BSHELL " " _PATH_SSH_SYSTEM_RC, "w"); 1189 if (f) { 1190 if (do_xauth) 1191 fprintf(f, "%s %s\n", s->auth_proto, 1192 s->auth_data); 1193 pclose(f); 1194 } else 1195 fprintf(stderr, "Could not run %s\n", 1196 _PATH_SSH_SYSTEM_RC); 1197 } else if (do_xauth && options.xauth_location != NULL) { 1198 /* Add authority data to .Xauthority if appropriate. */ 1199 if (debug_flag) { 1200 fprintf(stderr, 1201 "Running %.500s add " 1202 "%.100s %.100s %.100s\n", 1203 options.xauth_location, s->auth_display, 1204 s->auth_proto, s->auth_data); 1205 } 1206 snprintf(cmd, sizeof cmd, "%s -q -", 1207 options.xauth_location); 1208 f = popen(cmd, "w"); 1209 if (f) { 1210 fprintf(f, "add %s %s %s\n", 1211 s->auth_display, s->auth_proto, 1212 s->auth_data); 1213 pclose(f); 1214 } else { 1215 fprintf(stderr, "Could not run %s\n", 1216 cmd); 1217 } 1218 } 1219 } 1220 1221 /* Disallow logins if /etc/nologin exists. This does not apply to root. */ 1222 static void 1223 do_nologin(struct passwd *pw) 1224 { 1225 FILE *f = NULL; 1226 char buf[1024]; 1227 struct stat sb; 1228 1229 if (pw->pw_uid == 0) 1230 return; 1231 1232 if (stat(_PATH_NOLOGIN, &sb) == -1) 1233 return; 1234 1235 /* /etc/nologin exists. Print its contents if we can and exit. */ 1236 log("User %.100s not allowed because %s exists.", pw->pw_name, 1237 _PATH_NOLOGIN); 1238 if ((f = fopen(_PATH_NOLOGIN, "r")) != NULL) { 1239 while (fgets(buf, sizeof(buf), f)) 1240 fputs(buf, stderr); 1241 fclose(f); 1242 } 1243 exit(254); 1244 } 1245 1246 /* Chroot into ChrootDirectory if the option is set. */ 1247 void 1248 chroot_if_needed(struct passwd *pw) 1249 { 1250 char *chroot_path, *tmp; 1251 1252 if (chroot_requested(options.chroot_directory)) { 1253 tmp = tilde_expand_filename(options.chroot_directory, 1254 pw->pw_uid); 1255 chroot_path = percent_expand(tmp, "h", pw->pw_dir, 1256 "u", pw->pw_name, (char *)NULL); 1257 safely_chroot(chroot_path, pw->pw_uid); 1258 free(tmp); 1259 free(chroot_path); 1260 } 1261 } 1262 1263 /* 1264 * Chroot into a directory after checking it for safety: all path components 1265 * must be root-owned directories with strict permissions. 1266 */ 1267 static void 1268 safely_chroot(const char *path, uid_t uid) 1269 { 1270 const char *cp; 1271 char component[MAXPATHLEN]; 1272 struct stat st; 1273 1274 if (*path != '/') 1275 fatal("chroot path does not begin at root"); 1276 if (strlen(path) >= sizeof(component)) 1277 fatal("chroot path too long"); 1278 1279 /* 1280 * Descend the path, checking that each component is a 1281 * root-owned directory with strict permissions. 1282 */ 1283 for (cp = path; cp != NULL;) { 1284 if ((cp = strchr(cp, '/')) == NULL) 1285 strlcpy(component, path, sizeof(component)); 1286 else { 1287 cp++; 1288 memcpy(component, path, cp - path); 1289 component[cp - path] = '\0'; 1290 } 1291 1292 debug3("%s: checking '%s'", __func__, component); 1293 1294 if (stat(component, &st) != 0) 1295 fatal("%s: stat(\"%s\"): %s", __func__, 1296 component, strerror(errno)); 1297 if (st.st_uid != 0 || (st.st_mode & 022) != 0) 1298 fatal("bad ownership or modes for chroot " 1299 "directory %s\"%s\"", 1300 cp == NULL ? "" : "component ", component); 1301 if (!S_ISDIR(st.st_mode)) 1302 fatal("chroot path %s\"%s\" is not a directory", 1303 cp == NULL ? "" : "component ", component); 1304 } 1305 1306 if (chdir(path) == -1) 1307 fatal("Unable to chdir to chroot path \"%s\": " 1308 "%s", path, strerror(errno)); 1309 if (chroot(path) == -1) 1310 fatal("chroot(\"%s\"): %s", path, strerror(errno)); 1311 if (chdir("/") == -1) 1312 fatal("%s: chdir(/) after chroot: %s", 1313 __func__, strerror(errno)); 1314 verbose("Changed root directory to \"%s\"", path); 1315 } 1316 1317 static void 1318 launch_login(struct passwd *pw, const char *hostname) 1319 { 1320 /* Launch login(1). */ 1321 1322 execl(LOGIN_PROGRAM, "login", "-h", hostname, 1323 #ifdef xxxLOGIN_NEEDS_TERM 1324 (s->term ? s->term : "unknown"), 1325 #endif /* LOGIN_NEEDS_TERM */ 1326 #ifdef LOGIN_NO_ENDOPT 1327 "-p", "-f", pw->pw_name, (char *)NULL); 1328 #else 1329 "-p", "-f", "--", pw->pw_name, (char *)NULL); 1330 #endif 1331 1332 /* Login couldn't be executed, die. */ 1333 1334 perror("login"); 1335 exit(1); 1336 } 1337 1338 /* 1339 * Performs common processing for the child, such as setting up the 1340 * environment, closing extra file descriptors, setting the user and group 1341 * ids, and executing the command or shell. 1342 */ 1343 #define ARGV_MAX 10 1344 void 1345 do_child(Session *s, const char *command) 1346 { 1347 extern char **environ; 1348 char **env; 1349 char *argv[ARGV_MAX]; 1350 const char *shell, *shell0; 1351 struct passwd *pw = s->pw; 1352 1353 /* remove hostkey from the child's memory */ 1354 destroy_sensitive_data(); 1355 1356 do_nologin(pw); 1357 chroot_if_needed(pw); 1358 1359 /* 1360 * Get the shell from the password data. An empty shell field is 1361 * legal, and means /bin/sh. 1362 */ 1363 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; 1364 #ifdef HAVE_LOGIN_CAP 1365 shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell); 1366 #endif 1367 1368 env = do_setup_env(s, shell); 1369 1370 /* 1371 * Close the connection descriptors; note that this is the child, and 1372 * the server will still have the socket open, and it is important 1373 * that we do not shutdown it. Note that the descriptors cannot be 1374 * closed before building the environment, as we call 1375 * get_remote_ipaddr there. 1376 */ 1377 if (packet_get_connection_in() == packet_get_connection_out()) 1378 close(packet_get_connection_in()); 1379 else { 1380 close(packet_get_connection_in()); 1381 close(packet_get_connection_out()); 1382 } 1383 /* 1384 * Close all descriptors related to channels. They will still remain 1385 * open in the parent. 1386 */ 1387 /* XXX better use close-on-exec? -markus */ 1388 channel_close_all(); 1389 1390 /* 1391 * Close any extra file descriptors. Note that there may still be 1392 * descriptors left by system functions. They will be closed later. 1393 */ 1394 endpwent(); 1395 1396 /* 1397 * Must switch to the new environment variables so that .ssh/rc, 1398 * /etc/ssh/sshrc, and xauth are run in the proper environment. 1399 */ 1400 environ = env; 1401 1402 /* 1403 * New environment has been installed. We need to update locale 1404 * so that error messages beyond this point have the proper 1405 * character encoding. 1406 */ 1407 (void) setlocale(LC_ALL, ""); 1408 1409 /* 1410 * Close any extra open file descriptors so that we don\'t have them 1411 * hanging around in clients. Note that we want to do this after 1412 * initgroups, because at least on Solaris 2.3 it leaves file 1413 * descriptors open. 1414 */ 1415 closefrom(STDERR_FILENO + 1); 1416 1417 #ifdef AFS 1418 /* Try to get AFS tokens for the local cell. */ 1419 if (k_hasafs()) { 1420 char cell[64]; 1421 1422 if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0) 1423 krb_afslog(cell, 0); 1424 1425 krb_afslog(0, 0); 1426 } 1427 #endif /* AFS */ 1428 1429 /* Change current directory to the user's home directory. */ 1430 if (chdir(pw->pw_dir) < 0) { 1431 /* Suppress missing homedir warning for chroot case */ 1432 if (!chroot_requested(options.chroot_directory)) 1433 fprintf(stderr, "Could not chdir to home " 1434 "directory %s: %s\n", pw->pw_dir, 1435 strerror(errno)); 1436 } 1437 1438 do_rc_files(s, shell); 1439 1440 /* restore SIGPIPE for child */ 1441 signal(SIGPIPE, SIG_DFL); 1442 1443 if (s->is_subsystem == SUBSYSTEM_INT_SFTP) { 1444 int i; 1445 char *p, *args; 1446 extern int optind, optreset; 1447 1448 /* This will set the E/P sets here, simulating exec(2). */ 1449 drop_privs(pw->pw_uid); 1450 1451 setproctitle("%s@internal-sftp-server", s->pw->pw_name); 1452 args = xstrdup(command ? command : "sftp-server"); 1453 1454 i = 0; 1455 for ((p = strtok(args, " ")); p != NULL; (p = strtok(NULL, " "))) { 1456 if (i < ARGV_MAX - 1) 1457 argv[i++] = p; 1458 } 1459 1460 argv[i] = NULL; 1461 optind = optreset = 1; 1462 __progname = argv[0]; 1463 exit(sftp_server_main(i, argv, s->pw)); 1464 } 1465 1466 /* Get the last component of the shell name. */ 1467 if ((shell0 = strrchr(shell, '/')) != NULL) 1468 shell0++; 1469 else 1470 shell0 = shell; 1471 1472 /* 1473 * If we have no command, execute the shell. In this case, the shell 1474 * name to be passed in argv[0] is preceded by '-' to indicate that 1475 * this is a login shell. 1476 */ 1477 if (!command) { 1478 char argv0[256]; 1479 1480 /* Start the shell. Set initial character to '-'. */ 1481 argv0[0] = '-'; 1482 1483 if (strlcpy(argv0 + 1, shell0, sizeof(argv0) - 1) 1484 >= sizeof(argv0) - 1) { 1485 errno = EINVAL; 1486 perror(shell); 1487 exit(1); 1488 } 1489 1490 /* Execute the shell. */ 1491 argv[0] = argv0; 1492 argv[1] = NULL; 1493 execve(shell, argv, env); 1494 1495 /* Executing the shell failed. */ 1496 perror(shell); 1497 exit(1); 1498 } 1499 /* 1500 * Execute the command using the user's shell. This uses the -c 1501 * option to execute the command. 1502 */ 1503 argv[0] = (char *) shell0; 1504 argv[1] = "-c"; 1505 argv[2] = (char *) command; 1506 argv[3] = NULL; 1507 execve(shell, argv, env); 1508 perror(shell); 1509 exit(1); 1510 } 1511 1512 Session * 1513 session_new(void) 1514 { 1515 int i; 1516 static int did_init = 0; 1517 if (!did_init) { 1518 debug("session_new: init"); 1519 for (i = 0; i < MAX_SESSIONS; i++) { 1520 sessions[i].used = 0; 1521 } 1522 did_init = 1; 1523 } 1524 for (i = 0; i < MAX_SESSIONS; i++) { 1525 Session *s = &sessions[i]; 1526 if (! s->used) { 1527 memset(s, 0, sizeof(*s)); 1528 s->chanid = -1; 1529 s->ptyfd = -1; 1530 s->ttyfd = -1; 1531 s->used = 1; 1532 s->self = i; 1533 s->env = NULL; 1534 debug("session_new: session %d", i); 1535 return s; 1536 } 1537 } 1538 return NULL; 1539 } 1540 1541 static void 1542 session_dump(void) 1543 { 1544 int i; 1545 for (i = 0; i < MAX_SESSIONS; i++) { 1546 Session *s = &sessions[i]; 1547 debug("dump: used %d session %d %p channel %d pid %ld", 1548 s->used, 1549 s->self, 1550 s, 1551 s->chanid, 1552 (long)s->pid); 1553 } 1554 } 1555 1556 int 1557 session_open(Authctxt *authctxt, int chanid) 1558 { 1559 Session *s = session_new(); 1560 debug("session_open: channel %d", chanid); 1561 if (s == NULL) { 1562 error("no more sessions"); 1563 return 0; 1564 } 1565 s->authctxt = authctxt; 1566 s->pw = authctxt->pw; 1567 if (s->pw == NULL) 1568 fatal("no user for session %d", s->self); 1569 debug("session_open: session %d: link with channel %d", s->self, chanid); 1570 s->chanid = chanid; 1571 return 1; 1572 } 1573 1574 #ifndef lint 1575 Session * 1576 session_by_tty(char *tty) 1577 { 1578 int i; 1579 for (i = 0; i < MAX_SESSIONS; i++) { 1580 Session *s = &sessions[i]; 1581 if (s->used && s->ttyfd != -1 && strcmp(s->tty, tty) == 0) { 1582 debug("session_by_tty: session %d tty %s", i, tty); 1583 return s; 1584 } 1585 } 1586 debug("session_by_tty: unknown tty %.100s", tty); 1587 session_dump(); 1588 return NULL; 1589 } 1590 #endif /* lint */ 1591 1592 static Session * 1593 session_by_channel(int id) 1594 { 1595 int i; 1596 for (i = 0; i < MAX_SESSIONS; i++) { 1597 Session *s = &sessions[i]; 1598 if (s->used && s->chanid == id) { 1599 debug("session_by_channel: session %d channel %d", i, id); 1600 return s; 1601 } 1602 } 1603 debug("session_by_channel: unknown channel %d", id); 1604 session_dump(); 1605 return NULL; 1606 } 1607 1608 static Session * 1609 session_by_pid(pid_t pid) 1610 { 1611 int i; 1612 debug("session_by_pid: pid %ld", (long)pid); 1613 for (i = 0; i < MAX_SESSIONS; i++) { 1614 Session *s = &sessions[i]; 1615 if (s->used && s->pid == pid) 1616 return s; 1617 } 1618 error("session_by_pid: unknown pid %ld", (long)pid); 1619 session_dump(); 1620 return NULL; 1621 } 1622 1623 static int 1624 session_window_change_req(Session *s) 1625 { 1626 s->col = packet_get_int(); 1627 s->row = packet_get_int(); 1628 s->xpixel = packet_get_int(); 1629 s->ypixel = packet_get_int(); 1630 packet_check_eom(); 1631 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 1632 return 1; 1633 } 1634 1635 static int 1636 session_pty_req(Session *s) 1637 { 1638 u_int len; 1639 int n_bytes; 1640 1641 if (no_pty_flag) { 1642 debug("Allocating a pty not permitted for this authentication."); 1643 return 0; 1644 } 1645 if (s->ttyfd != -1) { 1646 packet_disconnect("Protocol error: you already have a pty."); 1647 return 0; 1648 } 1649 1650 s->term = packet_get_string(&len); 1651 1652 if (compat20) { 1653 s->col = packet_get_int(); 1654 s->row = packet_get_int(); 1655 } else { 1656 s->row = packet_get_int(); 1657 s->col = packet_get_int(); 1658 } 1659 s->xpixel = packet_get_int(); 1660 s->ypixel = packet_get_int(); 1661 1662 if (strcmp(s->term, "") == 0) { 1663 xfree(s->term); 1664 s->term = NULL; 1665 } 1666 1667 /* Allocate a pty and open it. */ 1668 debug("Allocating pty."); 1669 if (!pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty))) { 1670 if (s->term) 1671 xfree(s->term); 1672 s->term = NULL; 1673 s->ptyfd = -1; 1674 s->ttyfd = -1; 1675 error("session_pty_req: session %d alloc failed", s->self); 1676 return 0; 1677 } 1678 debug("session_pty_req: session %d alloc %s", s->self, s->tty); 1679 1680 /* for SSH1 the tty modes length is not given */ 1681 if (!compat20) 1682 n_bytes = packet_remaining(); 1683 tty_parse_modes(s->ttyfd, &n_bytes); 1684 1685 /* 1686 * Add a cleanup function to clear the utmp entry and record logout 1687 * time in case we call fatal() (e.g., the connection gets closed). 1688 */ 1689 fatal_add_cleanup(session_pty_cleanup, (void *)s); 1690 pty_setowner(s->pw, s->tty); 1691 1692 /* Set window size from the packet. */ 1693 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 1694 1695 packet_check_eom(); 1696 session_proctitle(s); 1697 return 1; 1698 } 1699 1700 static int 1701 session_subsystem_req(Session *s) 1702 { 1703 struct stat st; 1704 u_int len; 1705 int success = 0; 1706 char *prog, *cmd, *subsys = packet_get_string(&len); 1707 u_int i; 1708 1709 packet_check_eom(); 1710 log("subsystem request for %.100s", subsys); 1711 1712 for (i = 0; i < options.num_subsystems; i++) { 1713 if (strcmp(subsys, options.subsystem_name[i]) == 0) { 1714 prog = options.subsystem_command[i]; 1715 cmd = options.subsystem_args[i]; 1716 if (strcmp(INTERNAL_SFTP_NAME, prog) == 0) { 1717 s->is_subsystem = SUBSYSTEM_INT_SFTP; 1718 /* 1719 * We must stat(2) the subsystem before we chroot in 1720 * order to be able to send a proper error message. 1721 */ 1722 } else if (chroot_requested(options.chroot_directory)) { 1723 char chdirsub[MAXPATHLEN]; 1724 1725 strlcpy(chdirsub, options.chroot_directory, 1726 sizeof (chdirsub)); 1727 strlcat(chdirsub, "/", sizeof (chdirsub)); 1728 strlcat(chdirsub, prog, sizeof (chdirsub)); 1729 if (stat(chdirsub, &st) < 0) { 1730 error("subsystem: cannot stat %s under " 1731 "chroot directory %s: %s", prog, 1732 options.chroot_directory, 1733 strerror(errno)); 1734 if (strcmp(subsys, "sftp") == 0) 1735 error("subsystem: please see " 1736 "the Subsystem option in " 1737 "sshd_config(4) for an " 1738 "explanation of '%s'.", 1739 INTERNAL_SFTP_NAME); 1740 break; 1741 } 1742 } else if (stat(prog, &st) < 0) { 1743 error("subsystem: cannot stat %s: %s", prog, 1744 strerror(errno)); 1745 break; 1746 } else { 1747 s->is_subsystem = SUBSYSTEM_EXT; 1748 } 1749 debug("subsystem: exec() %s", cmd); 1750 do_exec(s, cmd); 1751 success = 1; 1752 break; 1753 } 1754 } 1755 1756 if (!success) 1757 log("subsystem request for %.100s failed, subsystem not found", 1758 subsys); 1759 1760 xfree(subsys); 1761 return success; 1762 } 1763 1764 /* 1765 * Serve "x11-req" channel request for X11 forwarding for the current session 1766 * channel. 1767 */ 1768 static int 1769 session_x11_req(Session *s) 1770 { 1771 int success, fd; 1772 char xauthdir[] = "/tmp/ssh-xauth-XXXXXX"; 1773 1774 s->single_connection = packet_get_char(); 1775 s->auth_proto = packet_get_string(NULL); 1776 s->auth_data = packet_get_string(NULL); 1777 s->screen = packet_get_int(); 1778 packet_check_eom(); 1779 1780 success = session_setup_x11fwd(s); 1781 if (!success) { 1782 xfree(s->auth_proto); 1783 xfree(s->auth_data); 1784 s->auth_proto = NULL; 1785 s->auth_data = NULL; 1786 return (success); 1787 } 1788 1789 /* 1790 * Create per session X authority file so that different sessions 1791 * don't contend for one common file. The reason for this is that 1792 * xauth(1) locking doesn't work too well over network filesystems. 1793 * 1794 * If mkdtemp() or open() fails then s->auth_file remains NULL which 1795 * means that we won't set XAUTHORITY variable in child's environment 1796 * and xauth(1) will use the default location for the authority file. 1797 */ 1798 if (mkdtemp(xauthdir) != NULL) { 1799 s->auth_file = xmalloc(MAXPATHLEN); 1800 snprintf(s->auth_file, MAXPATHLEN, "%s/xauthfile", 1801 xauthdir); 1802 /* 1803 * we don't want that "creating new authority file" message to 1804 * be printed by xauth(1) so we must create that file 1805 * beforehand. 1806 */ 1807 if ((fd = open(s->auth_file, O_CREAT | O_EXCL | O_RDONLY, 1808 S_IRUSR | S_IWUSR)) == -1) { 1809 error("failed to create the temporary X authority " 1810 "file %s: %.100s; will use the default one", 1811 s->auth_file, strerror(errno)); 1812 xfree(s->auth_file); 1813 s->auth_file = NULL; 1814 if (rmdir(xauthdir) == -1) { 1815 error("cannot remove xauth directory %s: %.100s", 1816 xauthdir, strerror(errno)); 1817 } 1818 } else { 1819 close(fd); 1820 debug("temporary X authority file %s created", 1821 s->auth_file); 1822 1823 /* 1824 * add a cleanup function to remove the temporary 1825 * xauth file in case we call fatal() (e.g., the 1826 * connection gets closed). 1827 */ 1828 fatal_add_cleanup(session_xauthfile_cleanup, (void *)s); 1829 } 1830 } 1831 else { 1832 error("failed to create a directory for the temporary X " 1833 "authority file: %.100s; will use the default xauth file", 1834 strerror(errno)); 1835 } 1836 1837 return (success); 1838 } 1839 1840 static int 1841 session_shell_req(Session *s) 1842 { 1843 packet_check_eom(); 1844 do_exec(s, NULL); 1845 return 1; 1846 } 1847 1848 static int 1849 session_exec_req(Session *s) 1850 { 1851 u_int len; 1852 char *command = packet_get_string(&len); 1853 packet_check_eom(); 1854 do_exec(s, command); 1855 xfree(command); 1856 return 1; 1857 } 1858 1859 static int 1860 session_auth_agent_req(Session *s) 1861 { 1862 static int called = 0; 1863 packet_check_eom(); 1864 if (no_agent_forwarding_flag) { 1865 debug("session_auth_agent_req: no_agent_forwarding_flag"); 1866 return 0; 1867 } 1868 if (called) { 1869 return 0; 1870 } else { 1871 called = 1; 1872 return auth_input_request_forwarding(s->pw); 1873 } 1874 } 1875 1876 static int 1877 session_loc_env_check(char *var, char *val) 1878 { 1879 char *current; 1880 int cat, ret; 1881 1882 if (strcmp(var, "LANG") == 0) 1883 cat = LC_ALL; 1884 else if (strcmp(var, "LC_ALL") == 0) 1885 cat = LC_ALL; 1886 else if (strcmp(var, "LC_CTYPE") == 0) 1887 cat = LC_CTYPE; 1888 else if (strcmp(var, "LC_COLLATE") == 0) 1889 cat = LC_COLLATE; 1890 else if (strcmp(var, "LC_TIME") == 0) 1891 cat = LC_TIME; 1892 else if (strcmp(var, "LC_NUMERIC") == 0) 1893 cat = LC_NUMERIC; 1894 else if (strcmp(var, "LC_MONETARY") == 0) 1895 cat = LC_MONETARY; 1896 else if (strcmp(var, "LC_MESSAGES") == 0) 1897 cat = LC_MESSAGES; 1898 1899 current = setlocale(cat, NULL); 1900 1901 ret = (setlocale(cat, val) != NULL); 1902 (void) setlocale(cat, current); 1903 return (ret); 1904 } 1905 1906 static int 1907 session_env_req(Session *s) 1908 { 1909 Channel *c; 1910 char *var, *val, *e; 1911 char **p; 1912 size_t len; 1913 int ret = 0; 1914 1915 /* Get var/val from the rest of this packet */ 1916 var = packet_get_string(NULL); 1917 val = packet_get_string(NULL); 1918 1919 /* 1920 * We'll need the channel ID for the packet_send_debug messages, 1921 * so get it now. 1922 */ 1923 if ((c = channel_lookup(s->chanid)) == NULL) 1924 goto done; /* shouldn't happen! */ 1925 1926 debug2("Received request for environment variable %s=%s", var, val); 1927 1928 /* For now allow only LANG and LC_* */ 1929 if (strcmp(var, "LANG") != 0 && strncmp(var, "LC_", 3) != 0) { 1930 debug2("Rejecting request for environment variable %s", var); 1931 goto done; 1932 } 1933 1934 if (!session_loc_env_check(var, val)) { 1935 packet_send_debug(gettext("Missing locale support for %s=%s"), 1936 var, val); 1937 goto done; 1938 } 1939 1940 packet_send_debug(gettext("Channel %d set: %s=%s"), c->remote_id, 1941 var, val); 1942 1943 /* 1944 * Always append new environment variables without regard to old 1945 * ones being overriden. The way these are actually added to 1946 * the environment of the session process later settings 1947 * override earlier ones; see copy_environment(). 1948 */ 1949 if (s->env == NULL) { 1950 char **env; 1951 1952 env = xmalloc(sizeof (char **) * 2); 1953 memset(env, 0, sizeof (char **) * 2); 1954 1955 s->env = env; 1956 p = env; 1957 } else { 1958 for (p = s->env; *p != NULL ; p++); 1959 1960 s->env = xrealloc(s->env, (p - s->env + 2) * sizeof (char **)); 1961 1962 for (p = s->env; *p != NULL ; p++); 1963 } 1964 1965 len = snprintf(NULL, 0, "%s=%s", var, val); 1966 e = xmalloc(len + 1); 1967 (void) snprintf(e, len + 1, "%s=%s", var, val); 1968 1969 (*p++) = e; 1970 *p = NULL; 1971 1972 ret = 1; 1973 1974 done: 1975 xfree(var); 1976 xfree(val); 1977 1978 return (ret); 1979 } 1980 1981 static void 1982 session_free_env(char ***envp) 1983 { 1984 char **env, **p; 1985 1986 if (envp == NULL || *envp == NULL) 1987 return; 1988 1989 env = *envp; 1990 1991 *envp = NULL; 1992 1993 for (p = env; *p != NULL; p++) 1994 xfree(*p); 1995 1996 xfree(env); 1997 } 1998 1999 int 2000 session_input_channel_req(Channel *c, const char *rtype) 2001 { 2002 int success = 0; 2003 Session *s; 2004 2005 if ((s = session_by_channel(c->self)) == NULL) { 2006 log("session_input_channel_req: no session %d req %.100s", 2007 c->self, rtype); 2008 return 0; 2009 } 2010 debug("session_input_channel_req: session %d req %s", s->self, rtype); 2011 2012 /* 2013 * a session is in LARVAL state until a shell, a command 2014 * or a subsystem is executed 2015 */ 2016 if (c->type == SSH_CHANNEL_LARVAL) { 2017 if (strcmp(rtype, "shell") == 0) { 2018 success = session_shell_req(s); 2019 } else if (strcmp(rtype, "exec") == 0) { 2020 success = session_exec_req(s); 2021 } else if (strcmp(rtype, "pty-req") == 0) { 2022 success = session_pty_req(s); 2023 } else if (strcmp(rtype, "x11-req") == 0) { 2024 success = session_x11_req(s); 2025 } else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) { 2026 success = session_auth_agent_req(s); 2027 } else if (strcmp(rtype, "subsystem") == 0) { 2028 success = session_subsystem_req(s); 2029 } else if (strcmp(rtype, "env") == 0) { 2030 success = session_env_req(s); 2031 } 2032 } 2033 if (strcmp(rtype, "window-change") == 0) { 2034 success = session_window_change_req(s); 2035 } 2036 return success; 2037 } 2038 2039 void 2040 session_set_fds(Session *s, int fdin, int fdout, int fderr) 2041 { 2042 if (!compat20) 2043 fatal("session_set_fds: called for proto != 2.0"); 2044 /* 2045 * now that have a child and a pipe to the child, 2046 * we can activate our channel and register the fd's 2047 */ 2048 if (s->chanid == -1) 2049 fatal("no channel for session %d", s->self); 2050 channel_set_fds(s->chanid, 2051 fdout, fdin, fderr, 2052 fderr == -1 ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ, 2053 1, 2054 CHAN_SES_WINDOW_DEFAULT); 2055 } 2056 2057 /* 2058 * Function to perform pty cleanup. Also called if we get aborted abnormally 2059 * (e.g., due to a dropped connection). 2060 */ 2061 void 2062 session_pty_cleanup2(void *session) 2063 { 2064 Session *s = session; 2065 2066 if (s == NULL) { 2067 error("session_pty_cleanup: no session"); 2068 return; 2069 } 2070 if (s->ttyfd == -1) 2071 return; 2072 2073 debug("session_pty_cleanup: session %d release %s", s->self, s->tty); 2074 2075 #ifdef USE_PAM 2076 session_do_pam(s, 0); 2077 #endif /* USE_PAM */ 2078 2079 /* Record that the user has logged out. */ 2080 if (s->pid != 0) { 2081 debug3("Recording SSHv2 channel logout in utmpx/wtmpx"); 2082 #ifdef ALTPRIVSEP 2083 altprivsep_record_logout(s->pid); 2084 #endif /* ALTPRIVSEP */ 2085 } 2086 2087 /* Release the pseudo-tty. */ 2088 if (getuid() == 0) 2089 pty_release(s->tty); 2090 2091 /* 2092 * Close the server side of the socket pairs. We must do this after 2093 * the pty cleanup, so that another process doesn't get this pty 2094 * while we're still cleaning up. 2095 */ 2096 if (close(s->ptymaster) < 0) 2097 error("close(s->ptymaster/%d): %s", s->ptymaster, strerror(errno)); 2098 2099 /* unlink pty from session */ 2100 s->ttyfd = -1; 2101 } 2102 2103 void 2104 session_pty_cleanup(void *session) 2105 { 2106 session_pty_cleanup2(session); 2107 } 2108 2109 /* 2110 * We use a different temporary X authority file per every session so we 2111 * should remove those files when fatal() is called. 2112 */ 2113 void 2114 session_xauthfile_cleanup(void *session) 2115 { 2116 Session *s = session; 2117 2118 if (s == NULL) { 2119 error("session_xauthfile_cleanup: no session"); 2120 return; 2121 } 2122 2123 debug("session_xauthfile_cleanup: session %d removing %s", s->self, 2124 s->auth_file); 2125 2126 if (unlink(s->auth_file) == -1) { 2127 error("session_xauthfile_cleanup: cannot remove xauth file: " 2128 "%.100s", strerror(errno)); 2129 return; 2130 } 2131 2132 /* dirname() will modify s->auth_file but that's ok */ 2133 if (rmdir(dirname(s->auth_file)) == -1) { 2134 error("session_xauthfile_cleanup: " 2135 "cannot remove xauth directory: %.100s", strerror(errno)); 2136 return; 2137 } 2138 } 2139 2140 static char * 2141 sig2name(int sig) 2142 { 2143 #define SSH_SIG(x) if (sig == SIG ## x) return #x 2144 SSH_SIG(ABRT); 2145 SSH_SIG(ALRM); 2146 SSH_SIG(FPE); 2147 SSH_SIG(HUP); 2148 SSH_SIG(ILL); 2149 SSH_SIG(INT); 2150 SSH_SIG(KILL); 2151 SSH_SIG(PIPE); 2152 SSH_SIG(QUIT); 2153 SSH_SIG(SEGV); 2154 SSH_SIG(TERM); 2155 SSH_SIG(USR1); 2156 SSH_SIG(USR2); 2157 #undef SSH_SIG 2158 return "SIG@openssh.com"; 2159 } 2160 2161 static void 2162 session_exit_message(Session *s, int status) 2163 { 2164 Channel *c; 2165 2166 if ((c = channel_lookup(s->chanid)) == NULL) 2167 fatal("session_exit_message: session %d: no channel %d", 2168 s->self, s->chanid); 2169 debug("session_exit_message: session %d channel %d pid %ld", 2170 s->self, s->chanid, (long)s->pid); 2171 2172 if (WIFEXITED(status)) { 2173 channel_request_start(s->chanid, "exit-status", 0); 2174 packet_put_int(WEXITSTATUS(status)); 2175 packet_send(); 2176 } else if (WIFSIGNALED(status)) { 2177 channel_request_start(s->chanid, "exit-signal", 0); 2178 packet_put_cstring(sig2name(WTERMSIG(status))); 2179 #ifdef WCOREDUMP 2180 packet_put_char(WCOREDUMP(status)); 2181 #else /* WCOREDUMP */ 2182 packet_put_char(0); 2183 #endif /* WCOREDUMP */ 2184 packet_put_cstring(""); 2185 packet_put_cstring(""); 2186 packet_send(); 2187 } else { 2188 /* Some weird exit cause. Just exit. */ 2189 packet_disconnect("wait returned status %04x.", status); 2190 } 2191 2192 /* Ok to close channel now */ 2193 channel_set_wait_for_exit(s->chanid, 0); 2194 2195 /* disconnect channel */ 2196 debug("session_exit_message: release channel %d", s->chanid); 2197 channel_cancel_cleanup(s->chanid); 2198 /* 2199 * emulate a write failure with 'chan_write_failed', nobody will be 2200 * interested in data we write. 2201 * Note that we must not call 'chan_read_failed', since there could 2202 * be some more data waiting in the pipe. 2203 */ 2204 if (c->ostate != CHAN_OUTPUT_CLOSED) 2205 chan_write_failed(c); 2206 s->chanid = -1; 2207 } 2208 2209 void 2210 session_close(Session *s) 2211 { 2212 debug("session_close: session %d pid %ld", s->self, (long)s->pid); 2213 if (s->ttyfd != -1) { 2214 fatal_remove_cleanup(session_pty_cleanup, (void *)s); 2215 session_pty_cleanup(s); 2216 } 2217 if (s->auth_file != NULL) { 2218 fatal_remove_cleanup(session_xauthfile_cleanup, (void *)s); 2219 session_xauthfile_cleanup(s); 2220 xfree(s->auth_file); 2221 } 2222 if (s->term) 2223 xfree(s->term); 2224 if (s->display) 2225 xfree(s->display); 2226 if (s->auth_display) 2227 xfree(s->auth_display); 2228 if (s->auth_data) 2229 xfree(s->auth_data); 2230 if (s->auth_proto) 2231 xfree(s->auth_proto); 2232 if (s->command) 2233 xfree(s->command); 2234 session_free_env(&s->env); 2235 s->used = 0; 2236 session_proctitle(s); 2237 } 2238 2239 void 2240 session_close_by_pid(pid_t pid, int status) 2241 { 2242 Session *s = session_by_pid(pid); 2243 if (s == NULL) { 2244 debug("session_close_by_pid: no session for pid %ld", 2245 (long)pid); 2246 return; 2247 } 2248 if (s->chanid != -1) 2249 session_exit_message(s, status); 2250 session_close(s); 2251 } 2252 2253 /* 2254 * This is called when a channel dies before the session 'child' itself dies. 2255 * It can happen for example if we exit from an interactive shell before we 2256 * exit from forwarded X11 applications. 2257 */ 2258 void 2259 session_close_by_channel(int id, void *arg) 2260 { 2261 Session *s = session_by_channel(id); 2262 if (s == NULL) { 2263 debug("session_close_by_channel: no session for id %d", id); 2264 return; 2265 } 2266 debug("session_close_by_channel: channel %d child %ld", 2267 id, (long)s->pid); 2268 if (s->pid != 0) { 2269 debug("session_close_by_channel: channel %d: has child", id); 2270 /* 2271 * delay detach of session, but release pty, since 2272 * the fd's to the child are already closed 2273 */ 2274 if (s->ttyfd != -1) { 2275 fatal_remove_cleanup(session_pty_cleanup, (void *)s); 2276 session_pty_cleanup(s); 2277 } 2278 return; 2279 } 2280 /* detach by removing callback */ 2281 channel_cancel_cleanup(s->chanid); 2282 s->chanid = -1; 2283 session_close(s); 2284 } 2285 2286 void 2287 session_destroy_all(void (*closefunc)(Session *)) 2288 { 2289 int i; 2290 for (i = 0; i < MAX_SESSIONS; i++) { 2291 Session *s = &sessions[i]; 2292 if (s->used) { 2293 if (closefunc != NULL) 2294 closefunc(s); 2295 else 2296 session_close(s); 2297 } 2298 } 2299 } 2300 2301 static char * 2302 session_tty_list(void) 2303 { 2304 static char buf[1024]; 2305 int i; 2306 buf[0] = '\0'; 2307 for (i = 0; i < MAX_SESSIONS; i++) { 2308 Session *s = &sessions[i]; 2309 if (s->used && s->ttyfd != -1) { 2310 if (buf[0] != '\0') 2311 strlcat(buf, ",", sizeof buf); 2312 strlcat(buf, strrchr(s->tty, '/') + 1, sizeof buf); 2313 } 2314 } 2315 if (buf[0] == '\0') 2316 strlcpy(buf, "notty", sizeof buf); 2317 return buf; 2318 } 2319 2320 void 2321 session_proctitle(Session *s) 2322 { 2323 if (s->pw == NULL) 2324 error("no user for session %d", s->self); 2325 else 2326 setproctitle("%s@%s", s->pw->pw_name, session_tty_list()); 2327 } 2328 2329 int 2330 session_setup_x11fwd(Session *s) 2331 { 2332 struct stat st; 2333 char display[512], auth_display[512]; 2334 char hostname[MAXHOSTNAMELEN]; 2335 2336 if (no_x11_forwarding_flag) { 2337 packet_send_debug("X11 forwarding disabled in user configuration file."); 2338 return 0; 2339 } 2340 if (!options.x11_forwarding) { 2341 debug("X11 forwarding disabled in server configuration file."); 2342 return 0; 2343 } 2344 if (!options.xauth_location || 2345 (stat(options.xauth_location, &st) == -1)) { 2346 packet_send_debug("No xauth program; cannot forward with spoofing."); 2347 return 0; 2348 } 2349 if (s->display != NULL) { 2350 debug("X11 display already set."); 2351 return 0; 2352 } 2353 if (x11_create_display_inet(options.x11_display_offset, 2354 options.x11_use_localhost, s->single_connection, 2355 &s->display_number) == -1) { 2356 debug("x11_create_display_inet failed."); 2357 return 0; 2358 } 2359 2360 /* Set up a suitable value for the DISPLAY variable. */ 2361 if (gethostname(hostname, sizeof(hostname)) < 0) 2362 fatal("gethostname: %.100s", strerror(errno)); 2363 /* 2364 * auth_display must be used as the displayname when the 2365 * authorization entry is added with xauth(1). This will be 2366 * different than the DISPLAY string for localhost displays. 2367 */ 2368 if (options.x11_use_localhost) { 2369 snprintf(display, sizeof display, "localhost:%u.%u", 2370 s->display_number, s->screen); 2371 snprintf(auth_display, sizeof auth_display, "unix:%u.%u", 2372 s->display_number, s->screen); 2373 s->display = xstrdup(display); 2374 s->auth_display = xstrdup(auth_display); 2375 } else { 2376 #ifdef IPADDR_IN_DISPLAY 2377 struct hostent *he; 2378 struct in_addr my_addr; 2379 2380 he = gethostbyname(hostname); 2381 if (he == NULL) { 2382 error("Can't get IP address for X11 DISPLAY."); 2383 packet_send_debug("Can't get IP address for X11 DISPLAY."); 2384 return 0; 2385 } 2386 memcpy(&my_addr, he->h_addr_list[0], sizeof(struct in_addr)); 2387 snprintf(display, sizeof display, "%.50s:%u.%u", inet_ntoa(my_addr), 2388 s->display_number, s->screen); 2389 #else 2390 snprintf(display, sizeof display, "%.400s:%u.%u", hostname, 2391 s->display_number, s->screen); 2392 #endif 2393 s->display = xstrdup(display); 2394 s->auth_display = xstrdup(display); 2395 } 2396 2397 return 1; 2398 } 2399 2400 #ifdef USE_PAM 2401 int session_do_pam_conv(int, struct pam_message **, 2402 struct pam_response **, void *); 2403 2404 static struct pam_conv session_pam_conv = { 2405 session_do_pam_conv, 2406 NULL 2407 }; 2408 2409 static void 2410 session_do_pam(Session *s, int do_open) 2411 { 2412 int pam_retval; 2413 char *where, *old_tty, *old_tty_copy = NULL; 2414 struct pam_conv old_conv, *old_conv_ptr; 2415 2416 if (!s || !s->authctxt || !s->authctxt->pam || !s->authctxt->pam->h) 2417 return; 2418 2419 /* Save current PAM item values */ 2420 where = "getting PAM_CONV"; 2421 pam_retval = pam_get_item(s->authctxt->pam->h, PAM_CONV, 2422 (void **) &old_conv_ptr); 2423 if (pam_retval != PAM_SUCCESS) 2424 goto done; 2425 old_conv = *old_conv_ptr; 2426 2427 where = "getting PAM_TTY"; 2428 pam_retval = pam_get_item(s->authctxt->pam->h, PAM_TTY, 2429 (void **) &old_tty); 2430 if (pam_retval != PAM_SUCCESS) 2431 goto done; 2432 old_tty_copy = xstrdup(old_tty); 2433 2434 /* Change PAM_TTY and PAM_CONV items */ 2435 where = "setting PAM_TTY"; 2436 pam_retval = pam_set_item(s->authctxt->pam->h, PAM_TTY, s->tty); 2437 if (pam_retval != PAM_SUCCESS) 2438 goto done; 2439 2440 where = "setting PAM_CONV"; 2441 session_pam_conv.appdata_ptr = s; 2442 pam_retval = pam_set_item(s->authctxt->pam->h, 2443 PAM_CONV, &session_pam_conv); 2444 if (pam_retval != PAM_SUCCESS) 2445 goto done; 2446 2447 /* Call pam_close_session(). pam_open_session was already called during 2448 * authentication, so don't do it again */ 2449 if (!do_open) { 2450 where = "calling pam_close_session()"; 2451 pam_retval = pam_close_session(s->authctxt->pam->h, 0); 2452 } 2453 2454 /* Reset PAM_TTY and PAM_CONV items to previous values */ 2455 where = "setting PAM_TTY"; 2456 pam_retval = pam_set_item(s->authctxt->pam->h, PAM_TTY, old_tty_copy); 2457 if (pam_retval != PAM_SUCCESS) 2458 goto done; 2459 2460 where = "setting PAM_CONV"; 2461 pam_retval = pam_set_item(s->authctxt->pam->h, PAM_CONV, &old_conv); 2462 if (pam_retval != PAM_SUCCESS) 2463 goto done; 2464 2465 session_pam_conv.appdata_ptr = NULL; 2466 2467 done: 2468 if (old_tty_copy) 2469 xfree(old_tty_copy); 2470 2471 if (pam_retval == PAM_SUCCESS) 2472 return; 2473 2474 /* fatal()? probably not... */ 2475 log("PAM failed[%d] while %s: %s", pam_retval, where, 2476 PAM_STRERROR(s->authctxt->pam->h, pam_retval)); 2477 } 2478 2479 int 2480 session_do_pam_conv(int num_prompts, 2481 struct pam_message **prompts, 2482 struct pam_response **resp, 2483 void *app_data) 2484 { 2485 Session *s = (Session *) app_data; 2486 2487 struct pam_response *reply; 2488 int count; 2489 char *prompt; 2490 2491 if (channel_lookup(s->chanid) == NULL) 2492 return PAM_CONV_ERR; 2493 2494 /* PAM will free this later */ 2495 reply = xmalloc(num_prompts * sizeof(*reply)); 2496 2497 (void) memset(reply, 0, num_prompts * sizeof(*reply)); 2498 for (count = 0; count < num_prompts; count++) { 2499 switch(PAM_MSG_MEMBER(prompts, count, msg_style)) { 2500 case PAM_TEXT_INFO: 2501 /* Write to stdout of channel */ 2502 prompt = PAM_MSG_MEMBER(prompts, count, msg); 2503 if (prompt != NULL && s->ttyfd != -1) { 2504 debug2("session_do_pam_conv: text info " 2505 "prompt: %s", prompt); 2506 (void) write(s->ttyfd, prompt, strlen(prompt)); 2507 (void) write(s->ttyfd, "\n", 1); 2508 } 2509 reply[count].resp = xstrdup(""); 2510 reply[count].resp_retcode = PAM_SUCCESS; 2511 break; 2512 case PAM_ERROR_MSG: 2513 /* Write to stderr of channel */ 2514 prompt = PAM_MSG_MEMBER(prompts, count, msg); 2515 if (prompt != NULL && s->ttyfd != -1) { 2516 debug2("session_do_pam_conv: error " 2517 "prompt: %s", prompt); 2518 (void) write(s->ttyfd, prompt, strlen(prompt)); 2519 (void) write(s->ttyfd, "\n", 1); 2520 } 2521 reply[count].resp = xstrdup(""); 2522 reply[count].resp_retcode = PAM_SUCCESS; 2523 break; 2524 case PAM_PROMPT_ECHO_ON: 2525 case PAM_PROMPT_ECHO_OFF: 2526 /* 2527 * XXX Someday add support for echo on/off prompts 2528 * here on sessions with ttys. 2529 */ 2530 default: 2531 xfree(reply); 2532 return PAM_CONV_ERR; 2533 } 2534 } 2535 2536 *resp = reply; 2537 2538 return PAM_SUCCESS; 2539 } 2540 #endif /* USE_PAM */ 2541 2542 static void 2543 do_authenticated2(Authctxt *authctxt) 2544 { 2545 server_loop2(authctxt); 2546 } 2547 2548 /* 2549 * Drop the privileges. We need this for the in-process SFTP server only. For 2550 * the shell and the external subsystem the exec(2) call will do the P = E = I 2551 * assignment itself. Never change the privileges if the connecting user is 2552 * root. See privileges(5) if the terminology used here is not known to you. 2553 */ 2554 static void 2555 drop_privs(uid_t uid) 2556 { 2557 priv_set_t *priv_inherit; 2558 2559 /* If root is connecting we are done. */ 2560 if (uid == 0) 2561 return; 2562 2563 if ((priv_inherit = priv_allocset()) == NULL) 2564 fatal("priv_allocset: %s", strerror(errno)); 2565 if (getppriv(PRIV_INHERITABLE, priv_inherit) != 0) 2566 fatal("getppriv: %s", strerror(errno)); 2567 2568 /* 2569 * This will limit E as well. Note that before this P was a 2570 * superset of I, see permanently_set_uid(). 2571 */ 2572 if (setppriv(PRIV_SET, PRIV_PERMITTED, priv_inherit) == -1) 2573 fatal("setppriv: %s", strerror(errno)); 2574 2575 priv_freeset(priv_inherit); 2576 2577 /* 2578 * By manipulating the P set above we entered a PA mode which we 2579 * do not need to retain in. 2580 */ 2581 if (setpflags(PRIV_AWARE, 0) == -1) 2582 fatal("setpflags: %s", strerror(errno)); 2583 } 2584