1 /* $NetBSD: session.c,v 1.5 2010/11/21 18:59:04 adam Exp $ */ 2 /* $OpenBSD: session.c,v 1.256 2010/06/25 07:20:04 djm Exp $ */ 3 /* 4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 5 * All rights reserved 6 * 7 * As far as I am concerned, the code I have written for this software 8 * can be used freely for any purpose. Any derived versions of this 9 * software must be clearly marked as such, and if the derived work is 10 * incompatible with the protocol description in the RFC file, it must be 11 * called by a name other than "ssh" or "Secure Shell". 12 * 13 * SSH2 support by Markus Friedl. 14 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 15 * 16 * Redistribution and use in source and binary forms, with or without 17 * modification, are permitted provided that the following conditions 18 * are met: 19 * 1. Redistributions of source code must retain the above copyright 20 * notice, this list of conditions and the following disclaimer. 21 * 2. Redistributions in binary form must reproduce the above copyright 22 * notice, this list of conditions and the following disclaimer in the 23 * documentation and/or other materials provided with the distribution. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 26 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 27 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 28 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 29 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 30 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 31 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 32 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 33 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 34 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 35 */ 36 37 #include "includes.h" 38 __RCSID("$NetBSD: session.c,v 1.5 2010/11/21 18:59:04 adam Exp $"); 39 #include <sys/types.h> 40 #include <sys/wait.h> 41 #include <sys/un.h> 42 #include <sys/stat.h> 43 #include <sys/socket.h> 44 #include <sys/param.h> 45 #include <sys/queue.h> 46 47 #include <errno.h> 48 #include <fcntl.h> 49 #include <grp.h> 50 #include <login_cap.h> 51 #include <paths.h> 52 #include <pwd.h> 53 #include <signal.h> 54 #include <stdio.h> 55 #include <stdlib.h> 56 #include <string.h> 57 #include <unistd.h> 58 59 #include "xmalloc.h" 60 #include "ssh.h" 61 #include "ssh1.h" 62 #include "ssh2.h" 63 #include "sshpty.h" 64 #include "packet.h" 65 #include "buffer.h" 66 #include "match.h" 67 #include "uidswap.h" 68 #include "compat.h" 69 #include "channels.h" 70 #include "key.h" 71 #include "cipher.h" 72 #include "kex.h" 73 #include "hostfile.h" 74 #include "auth.h" 75 #include "auth-options.h" 76 #include "pathnames.h" 77 #include "log.h" 78 #include "servconf.h" 79 #include "sshlogin.h" 80 #include "serverloop.h" 81 #include "canohost.h" 82 #include "misc.h" 83 #include "session.h" 84 #ifdef GSSAPI 85 #include "ssh-gss.h" 86 #endif 87 #include "monitor_wrap.h" 88 #include "sftp.h" 89 90 #ifdef KRB5 91 #include <kafs.h> 92 #endif 93 94 #define IS_INTERNAL_SFTP(c) \ 95 (!strncmp(c, INTERNAL_SFTP_NAME, sizeof(INTERNAL_SFTP_NAME) - 1) && \ 96 (c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\0' || \ 97 c[sizeof(INTERNAL_SFTP_NAME) - 1] == ' ' || \ 98 c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\t')) 99 100 /* func */ 101 102 Session *session_new(void); 103 void session_set_fds(Session *, int, int, int, int, int); 104 void session_pty_cleanup(Session *); 105 void session_proctitle(Session *); 106 int session_setup_x11fwd(Session *); 107 int do_exec_pty(Session *, const char *); 108 int do_exec_no_pty(Session *, const char *); 109 int do_exec(Session *, const char *); 110 void do_login(Session *, const char *); 111 void do_child(Session *, const char *); 112 void do_motd(void); 113 int check_quietlogin(Session *, const char *); 114 115 static void do_authenticated1(Authctxt *); 116 static void do_authenticated2(Authctxt *); 117 118 static int session_pty_req(Session *); 119 120 /* import */ 121 extern ServerOptions options; 122 extern char *__progname; 123 extern int log_stderr; 124 extern int debug_flag; 125 extern u_int utmp_len; 126 extern int startup_pipe; 127 extern void destroy_sensitive_data(void); 128 extern Buffer loginmsg; 129 130 /* original command from peer. */ 131 const char *original_command = NULL; 132 133 /* data */ 134 static int sessions_first_unused = -1; 135 static int sessions_nalloc = 0; 136 static Session *sessions = NULL; 137 138 #define SUBSYSTEM_NONE 0 139 #define SUBSYSTEM_EXT 1 140 #define SUBSYSTEM_INT_SFTP 2 141 #define SUBSYSTEM_INT_SFTP_ERROR 3 142 143 #ifdef HAVE_LOGIN_CAP 144 login_cap_t *lc; 145 #endif 146 147 static int is_child = 0; 148 149 /* Name and directory of socket for authentication agent forwarding. */ 150 static char *auth_sock_name = NULL; 151 static char *auth_sock_dir = NULL; 152 153 /* removes the agent forwarding socket */ 154 155 static void 156 auth_sock_cleanup_proc(struct passwd *pw) 157 { 158 if (auth_sock_name != NULL) { 159 temporarily_use_uid(pw); 160 unlink(auth_sock_name); 161 rmdir(auth_sock_dir); 162 auth_sock_name = NULL; 163 restore_uid(); 164 } 165 } 166 167 static int 168 auth_input_request_forwarding(struct passwd * pw) 169 { 170 Channel *nc; 171 int sock = -1; 172 struct sockaddr_un sunaddr; 173 174 if (auth_sock_name != NULL) { 175 error("authentication forwarding requested twice."); 176 return 0; 177 } 178 179 /* Temporarily drop privileged uid for mkdir/bind. */ 180 temporarily_use_uid(pw); 181 182 /* Allocate a buffer for the socket name, and format the name. */ 183 auth_sock_dir = xstrdup("/tmp/ssh-XXXXXXXXXX"); 184 185 /* Create private directory for socket */ 186 if (mkdtemp(auth_sock_dir) == NULL) { 187 packet_send_debug("Agent forwarding disabled: " 188 "mkdtemp() failed: %.100s", strerror(errno)); 189 restore_uid(); 190 xfree(auth_sock_dir); 191 auth_sock_dir = NULL; 192 goto authsock_err; 193 } 194 195 xasprintf(&auth_sock_name, "%s/agent.%ld", 196 auth_sock_dir, (long) getpid()); 197 198 /* Create the socket. */ 199 sock = socket(AF_UNIX, SOCK_STREAM, 0); 200 if (sock < 0) { 201 error("socket: %.100s", strerror(errno)); 202 restore_uid(); 203 goto authsock_err; 204 } 205 206 /* Bind it to the name. */ 207 memset(&sunaddr, 0, sizeof(sunaddr)); 208 sunaddr.sun_family = AF_UNIX; 209 strlcpy(sunaddr.sun_path, auth_sock_name, sizeof(sunaddr.sun_path)); 210 211 if (bind(sock, (struct sockaddr *)&sunaddr, sizeof(sunaddr)) < 0) { 212 error("bind: %.100s", strerror(errno)); 213 restore_uid(); 214 goto authsock_err; 215 } 216 217 /* Restore the privileged uid. */ 218 restore_uid(); 219 220 /* Start listening on the socket. */ 221 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) { 222 error("listen: %.100s", strerror(errno)); 223 goto authsock_err; 224 } 225 226 /* Allocate a channel for the authentication agent socket. */ 227 /* this shouldn't matter if its hpn or not - cjr */ 228 nc = channel_new("auth socket", 229 SSH_CHANNEL_AUTH_SOCKET, sock, sock, -1, 230 CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 231 0, "auth socket", 1); 232 nc->path = xstrdup(auth_sock_name); 233 return 1; 234 235 authsock_err: 236 if (auth_sock_name != NULL) 237 xfree(auth_sock_name); 238 if (auth_sock_dir != NULL) { 239 rmdir(auth_sock_dir); 240 xfree(auth_sock_dir); 241 } 242 if (sock != -1) 243 close(sock); 244 auth_sock_name = NULL; 245 auth_sock_dir = NULL; 246 return 0; 247 } 248 249 static void 250 display_loginmsg(void) 251 { 252 if (buffer_len(&loginmsg) > 0) { 253 buffer_append(&loginmsg, "\0", 1); 254 printf("%s", (char *)buffer_ptr(&loginmsg)); 255 buffer_clear(&loginmsg); 256 } 257 } 258 259 void 260 do_authenticated(Authctxt *authctxt) 261 { 262 setproctitle("%s", authctxt->pw->pw_name); 263 264 /* setup the channel layer */ 265 if (!no_port_forwarding_flag && options.allow_tcp_forwarding) 266 channel_permit_all_opens(); 267 268 auth_debug_send(); 269 270 if (compat20) 271 do_authenticated2(authctxt); 272 else 273 do_authenticated1(authctxt); 274 275 do_cleanup(authctxt); 276 } 277 278 /* 279 * Prepares for an interactive session. This is called after the user has 280 * been successfully authenticated. During this message exchange, pseudo 281 * terminals are allocated, X11, TCP/IP, and authentication agent forwardings 282 * are requested, etc. 283 */ 284 static void 285 do_authenticated1(Authctxt *authctxt) 286 { 287 Session *s; 288 char *command; 289 int success, type, screen_flag; 290 int enable_compression_after_reply = 0; 291 u_int proto_len, data_len, dlen, compression_level = 0; 292 293 s = session_new(); 294 if (s == NULL) { 295 error("no more sessions"); 296 return; 297 } 298 s->authctxt = authctxt; 299 s->pw = authctxt->pw; 300 301 /* 302 * We stay in this loop until the client requests to execute a shell 303 * or a command. 304 */ 305 for (;;) { 306 success = 0; 307 308 /* Get a packet from the client. */ 309 type = packet_read(); 310 311 /* Process the packet. */ 312 switch (type) { 313 case SSH_CMSG_REQUEST_COMPRESSION: 314 compression_level = packet_get_int(); 315 packet_check_eom(); 316 if (compression_level < 1 || compression_level > 9) { 317 packet_send_debug("Received invalid compression level %d.", 318 compression_level); 319 break; 320 } 321 if (options.compression == COMP_NONE) { 322 debug2("compression disabled"); 323 break; 324 } 325 /* Enable compression after we have responded with SUCCESS. */ 326 enable_compression_after_reply = 1; 327 success = 1; 328 break; 329 330 case SSH_CMSG_REQUEST_PTY: 331 success = session_pty_req(s); 332 break; 333 334 case SSH_CMSG_X11_REQUEST_FORWARDING: 335 s->auth_proto = packet_get_string(&proto_len); 336 s->auth_data = packet_get_string(&data_len); 337 338 screen_flag = packet_get_protocol_flags() & 339 SSH_PROTOFLAG_SCREEN_NUMBER; 340 debug2("SSH_PROTOFLAG_SCREEN_NUMBER: %d", screen_flag); 341 342 if (packet_remaining() == 4) { 343 if (!screen_flag) 344 debug2("Buggy client: " 345 "X11 screen flag missing"); 346 s->screen = packet_get_int(); 347 } else { 348 s->screen = 0; 349 } 350 packet_check_eom(); 351 success = session_setup_x11fwd(s); 352 if (!success) { 353 xfree(s->auth_proto); 354 xfree(s->auth_data); 355 s->auth_proto = NULL; 356 s->auth_data = NULL; 357 } 358 break; 359 360 case SSH_CMSG_AGENT_REQUEST_FORWARDING: 361 if (!options.allow_agent_forwarding || 362 no_agent_forwarding_flag || compat13) { 363 debug("Authentication agent forwarding not permitted for this authentication."); 364 break; 365 } 366 debug("Received authentication agent forwarding request."); 367 success = auth_input_request_forwarding(s->pw); 368 break; 369 370 case SSH_CMSG_PORT_FORWARD_REQUEST: 371 if (no_port_forwarding_flag) { 372 debug("Port forwarding not permitted for this authentication."); 373 break; 374 } 375 if (!options.allow_tcp_forwarding) { 376 debug("Port forwarding not permitted."); 377 break; 378 } 379 debug("Received TCP/IP port forwarding request."); 380 if (channel_input_port_forward_request(s->pw->pw_uid == 0, 381 options.gateway_ports) < 0) { 382 debug("Port forwarding failed."); 383 break; 384 } 385 success = 1; 386 break; 387 388 case SSH_CMSG_MAX_PACKET_SIZE: 389 if (packet_set_maxsize(packet_get_int()) > 0) 390 success = 1; 391 break; 392 393 #if defined(AFS) || defined(KRB5) 394 case SSH_CMSG_HAVE_KERBEROS_TGT: 395 if (!options.kerberos_tgt_passing) { 396 verbose("Kerberos TGT passing disabled."); 397 } else { 398 char *kdata = packet_get_string(&dlen); 399 packet_check_eom(); 400 401 /* XXX - 0x41, see creds_to_radix version */ 402 if (kdata[0] != 0x41) { 403 #ifdef KRB5 404 krb5_data tgt; 405 tgt.data = kdata; 406 tgt.length = dlen; 407 408 if (auth_krb5_tgt(s->authctxt, &tgt)) 409 success = 1; 410 else 411 verbose("Kerberos v5 TGT refused for %.100s", s->authctxt->user); 412 #endif /* KRB5 */ 413 } else { 414 #ifdef AFS 415 if (auth_krb4_tgt(s->authctxt, kdata)) 416 success = 1; 417 else 418 verbose("Kerberos v4 TGT refused for %.100s", s->authctxt->user); 419 #endif /* AFS */ 420 } 421 xfree(kdata); 422 } 423 break; 424 #endif /* AFS || KRB5 */ 425 426 #ifdef AFS 427 case SSH_CMSG_HAVE_AFS_TOKEN: 428 if (!options.afs_token_passing || !k_hasafs()) { 429 verbose("AFS token passing disabled."); 430 } else { 431 /* Accept AFS token. */ 432 char *token = packet_get_string(&dlen); 433 packet_check_eom(); 434 435 if (auth_afs_token(s->authctxt, token)) 436 success = 1; 437 else 438 verbose("AFS token refused for %.100s", 439 s->authctxt->user); 440 xfree(token); 441 } 442 break; 443 #endif /* AFS */ 444 445 case SSH_CMSG_EXEC_SHELL: 446 case SSH_CMSG_EXEC_CMD: 447 if (type == SSH_CMSG_EXEC_CMD) { 448 command = packet_get_string(&dlen); 449 debug("Exec command '%.500s'", command); 450 if (do_exec(s, command) != 0) 451 packet_disconnect( 452 "command execution failed"); 453 xfree(command); 454 } else { 455 if (do_exec(s, NULL) != 0) 456 packet_disconnect( 457 "shell execution failed"); 458 } 459 packet_check_eom(); 460 session_close(s); 461 return; 462 463 default: 464 /* 465 * Any unknown messages in this phase are ignored, 466 * and a failure message is returned. 467 */ 468 logit("Unknown packet type received after authentication: %d", type); 469 } 470 packet_start(success ? SSH_SMSG_SUCCESS : SSH_SMSG_FAILURE); 471 packet_send(); 472 packet_write_wait(); 473 474 /* Enable compression now that we have replied if appropriate. */ 475 if (enable_compression_after_reply) { 476 enable_compression_after_reply = 0; 477 packet_start_compression(compression_level); 478 } 479 } 480 } 481 482 #define USE_PIPES 483 /* 484 * This is called to fork and execute a command when we have no tty. This 485 * will call do_child from the child, and server_loop from the parent after 486 * setting up file descriptors and such. 487 */ 488 int 489 do_exec_no_pty(Session *s, const char *command) 490 { 491 pid_t pid; 492 #ifdef USE_PIPES 493 int pin[2], pout[2], perr[2]; 494 495 if (s == NULL) 496 fatal("do_exec_no_pty: no session"); 497 498 /* Allocate pipes for communicating with the program. */ 499 if (pipe(pin) < 0) { 500 error("%s: pipe in: %.100s", __func__, strerror(errno)); 501 return -1; 502 } 503 if (pipe(pout) < 0) { 504 error("%s: pipe out: %.100s", __func__, strerror(errno)); 505 close(pin[0]); 506 close(pin[1]); 507 return -1; 508 } 509 if (pipe(perr) < 0) { 510 error("%s: pipe err: %.100s", __func__, 511 strerror(errno)); 512 close(pin[0]); 513 close(pin[1]); 514 close(pout[0]); 515 close(pout[1]); 516 return -1; 517 } 518 #else 519 int inout[2], err[2]; 520 521 if (s == NULL) 522 fatal("do_exec_no_pty: no session"); 523 524 /* Uses socket pairs to communicate with the program. */ 525 if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) < 0) { 526 error("%s: socketpair #1: %.100s", __func__, strerror(errno)); 527 return -1; 528 } 529 if (socketpair(AF_UNIX, SOCK_STREAM, 0, err) < 0) { 530 error("%s: socketpair #2: %.100s", __func__, 531 strerror(errno)); 532 close(inout[0]); 533 close(inout[1]); 534 return -1; 535 } 536 #endif 537 538 session_proctitle(s); 539 540 #ifdef notdef 541 #if defined(USE_PAM) 542 if (options.use_pam && !use_privsep) 543 do_pam_setcred(1); 544 #endif /* USE_PAM */ 545 #endif 546 547 /* Fork the child. */ 548 switch ((pid = fork())) { 549 case -1: 550 error("%s: fork: %.100s", __func__, strerror(errno)); 551 #ifdef USE_PIPES 552 close(pin[0]); 553 close(pin[1]); 554 close(pout[0]); 555 close(pout[1]); 556 close(perr[0]); 557 close(perr[1]); 558 #else 559 close(inout[0]); 560 close(inout[1]); 561 close(err[0]); 562 close(err[1]); 563 #endif 564 return -1; 565 case 0: 566 is_child = 1; 567 568 /* Child. Reinitialize the log since the pid has changed. */ 569 log_init(__progname, options.log_level, 570 options.log_facility, log_stderr); 571 572 /* 573 * Create a new session and process group since the 4.4BSD 574 * setlogin() affects the entire process group. 575 */ 576 if (setsid() < 0) 577 error("setsid failed: %.100s", strerror(errno)); 578 579 #ifdef USE_PIPES 580 /* 581 * Redirect stdin. We close the parent side of the socket 582 * pair, and make the child side the standard input. 583 */ 584 close(pin[1]); 585 if (dup2(pin[0], 0) < 0) 586 perror("dup2 stdin"); 587 close(pin[0]); 588 589 /* Redirect stdout. */ 590 close(pout[0]); 591 if (dup2(pout[1], 1) < 0) 592 perror("dup2 stdout"); 593 close(pout[1]); 594 595 /* Redirect stderr. */ 596 close(perr[0]); 597 if (dup2(perr[1], 2) < 0) 598 perror("dup2 stderr"); 599 close(perr[1]); 600 #else 601 /* 602 * Redirect stdin, stdout, and stderr. Stdin and stdout will 603 * use the same socket, as some programs (particularly rdist) 604 * seem to depend on it. 605 */ 606 close(inout[1]); 607 close(err[1]); 608 if (dup2(inout[0], 0) < 0) /* stdin */ 609 perror("dup2 stdin"); 610 if (dup2(inout[0], 1) < 0) /* stdout (same as stdin) */ 611 perror("dup2 stdout"); 612 close(inout[0]); 613 if (dup2(err[0], 2) < 0) /* stderr */ 614 perror("dup2 stderr"); 615 close(err[0]); 616 #endif 617 618 /* Do processing for the child (exec command etc). */ 619 do_child(s, command); 620 /* NOTREACHED */ 621 default: 622 break; 623 } 624 625 s->pid = pid; 626 /* Set interactive/non-interactive mode. */ 627 packet_set_interactive(s->display != NULL); 628 629 #ifdef USE_PIPES 630 /* We are the parent. Close the child sides of the pipes. */ 631 close(pin[0]); 632 close(pout[1]); 633 close(perr[1]); 634 635 if (compat20) { 636 session_set_fds(s, pin[1], pout[0], perr[0], 637 s->is_subsystem, 0); 638 } else { 639 /* Enter the interactive session. */ 640 server_loop(pid, pin[1], pout[0], perr[0]); 641 /* server_loop has closed pin[1], pout[0], and perr[0]. */ 642 } 643 #else 644 /* We are the parent. Close the child sides of the socket pairs. */ 645 close(inout[0]); 646 close(err[0]); 647 648 /* 649 * Enter the interactive session. Note: server_loop must be able to 650 * handle the case that fdin and fdout are the same. 651 */ 652 if (compat20) { 653 session_set_fds(s, inout[1], inout[1], err[1], 654 s->is_subsystem, 0); 655 } else { 656 server_loop(pid, inout[1], inout[1], err[1]); 657 /* server_loop has closed inout[1] and err[1]. */ 658 } 659 #endif 660 return 0; 661 } 662 663 /* 664 * This is called to fork and execute a command when we have a tty. This 665 * will call do_child from the child, and server_loop from the parent after 666 * setting up file descriptors, controlling tty, updating wtmp, utmp, 667 * lastlog, and other such operations. 668 */ 669 int 670 do_exec_pty(Session *s, const char *command) 671 { 672 int fdout, ptyfd, ttyfd, ptymaster; 673 pid_t pid; 674 675 if (s == NULL) 676 fatal("do_exec_pty: no session"); 677 ptyfd = s->ptyfd; 678 ttyfd = s->ttyfd; 679 680 #if defined(USE_PAM) 681 if (options.use_pam) { 682 do_pam_set_tty(s->tty); 683 if (!use_privsep) 684 do_pam_setcred(1); 685 } 686 #endif 687 688 /* 689 * Create another descriptor of the pty master side for use as the 690 * standard input. We could use the original descriptor, but this 691 * simplifies code in server_loop. The descriptor is bidirectional. 692 * Do this before forking (and cleanup in the child) so as to 693 * detect and gracefully fail out-of-fd conditions. 694 */ 695 if ((fdout = dup(ptyfd)) < 0) { 696 error("%s: dup #1: %s", __func__, strerror(errno)); 697 close(ttyfd); 698 close(ptyfd); 699 return -1; 700 } 701 /* we keep a reference to the pty master */ 702 if ((ptymaster = dup(ptyfd)) < 0) { 703 error("%s: dup #2: %s", __func__, strerror(errno)); 704 close(ttyfd); 705 close(ptyfd); 706 close(fdout); 707 return -1; 708 } 709 710 /* Fork the child. */ 711 switch ((pid = fork())) { 712 case -1: 713 error("%s: fork: %.100s", __func__, strerror(errno)); 714 close(fdout); 715 close(ptymaster); 716 close(ttyfd); 717 close(ptyfd); 718 return -1; 719 case 0: 720 is_child = 1; 721 722 close(fdout); 723 close(ptymaster); 724 725 /* Child. Reinitialize the log because the pid has changed. */ 726 log_init(__progname, options.log_level, 727 options.log_facility, log_stderr); 728 /* Close the master side of the pseudo tty. */ 729 close(ptyfd); 730 731 /* Make the pseudo tty our controlling tty. */ 732 pty_make_controlling_tty(&ttyfd, s->tty); 733 734 /* Redirect stdin/stdout/stderr from the pseudo tty. */ 735 if (dup2(ttyfd, 0) < 0) 736 error("dup2 stdin: %s", strerror(errno)); 737 if (dup2(ttyfd, 1) < 0) 738 error("dup2 stdout: %s", strerror(errno)); 739 if (dup2(ttyfd, 2) < 0) 740 error("dup2 stderr: %s", strerror(errno)); 741 742 /* Close the extra descriptor for the pseudo tty. */ 743 close(ttyfd); 744 745 /* record login, etc. similar to login(1) */ 746 if (!(options.use_login && command == NULL)) 747 do_login(s, command); 748 749 /* 750 * Do common processing for the child, such as execing 751 * the command. 752 */ 753 do_child(s, command); 754 /* NOTREACHED */ 755 default: 756 break; 757 } 758 s->pid = pid; 759 760 /* Parent. Close the slave side of the pseudo tty. */ 761 close(ttyfd); 762 763 /* Enter interactive session. */ 764 s->ptymaster = ptymaster; 765 packet_set_interactive(1); 766 if (compat20) { 767 session_set_fds(s, ptyfd, fdout, -1, 1, 1); 768 } else { 769 server_loop(pid, ptyfd, fdout, -1); 770 /* server_loop _has_ closed ptyfd and fdout. */ 771 } 772 return 0; 773 } 774 775 /* 776 * This is called to fork and execute a command. If another command is 777 * to be forced, execute that instead. 778 */ 779 int 780 do_exec(Session *s, const char *command) 781 { 782 int ret; 783 784 if (options.adm_forced_command) { 785 original_command = command; 786 command = options.adm_forced_command; 787 if (IS_INTERNAL_SFTP(command)) { 788 s->is_subsystem = s->is_subsystem ? 789 SUBSYSTEM_INT_SFTP : SUBSYSTEM_INT_SFTP_ERROR; 790 } else if (s->is_subsystem) 791 s->is_subsystem = SUBSYSTEM_EXT; 792 debug("Forced command (config) '%.900s'", command); 793 } else if (forced_command) { 794 original_command = command; 795 command = forced_command; 796 if (IS_INTERNAL_SFTP(command)) { 797 s->is_subsystem = s->is_subsystem ? 798 SUBSYSTEM_INT_SFTP : SUBSYSTEM_INT_SFTP_ERROR; 799 } else if (s->is_subsystem) 800 s->is_subsystem = SUBSYSTEM_EXT; 801 debug("Forced command (key option) '%.900s'", command); 802 } 803 804 #ifdef GSSAPI 805 if (options.gss_authentication) { 806 temporarily_use_uid(s->pw); 807 ssh_gssapi_storecreds(); 808 restore_uid(); 809 } 810 #endif 811 if (s->ttyfd != -1) 812 ret = do_exec_pty(s, command); 813 else 814 ret = do_exec_no_pty(s, command); 815 816 original_command = NULL; 817 818 /* 819 * Clear loginmsg: it's the child's responsibility to display 820 * it to the user, otherwise multiple sessions may accumulate 821 * multiple copies of the login messages. 822 */ 823 buffer_clear(&loginmsg); 824 825 return ret; 826 } 827 828 829 /* administrative, login(1)-like work */ 830 void 831 do_login(Session *s, const char *command) 832 { 833 socklen_t fromlen; 834 struct sockaddr_storage from; 835 struct passwd * pw = s->pw; 836 pid_t pid = getpid(); 837 838 /* 839 * Get IP address of client. If the connection is not a socket, let 840 * the address be 0.0.0.0. 841 */ 842 memset(&from, 0, sizeof(from)); 843 fromlen = sizeof(from); 844 if (packet_connection_is_on_socket()) { 845 if (getpeername(packet_get_connection_in(), 846 (struct sockaddr *)&from, &fromlen) < 0) { 847 debug("getpeername: %.100s", strerror(errno)); 848 cleanup_exit(255); 849 } 850 } 851 852 /* Record that there was a login on that tty from the remote host. */ 853 if (!use_privsep) 854 record_login(pid, s->tty, pw->pw_name, pw->pw_uid, 855 get_remote_name_or_ip(utmp_len, 856 options.use_dns), 857 (struct sockaddr *)&from, fromlen); 858 859 #ifdef USE_PAM 860 /* 861 * If password change is needed, do it now. 862 * This needs to occur before the ~/.hushlogin check. 863 */ 864 if (options.use_pam && !use_privsep && s->authctxt->force_pwchange) { 865 display_loginmsg(); 866 do_pam_chauthtok(); 867 s->authctxt->force_pwchange = 0; 868 /* XXX - signal [net] parent to enable forwardings */ 869 } 870 #endif 871 872 if (check_quietlogin(s, command)) 873 return; 874 875 display_loginmsg(); 876 877 do_motd(); 878 } 879 880 /* 881 * Display the message of the day. 882 */ 883 void 884 do_motd(void) 885 { 886 FILE *f; 887 char buf[256]; 888 889 if (options.print_motd) { 890 #ifdef HAVE_LOGIN_CAP 891 f = fopen(login_getcapstr(lc, "welcome", "/etc/motd", 892 "/etc/motd"), "r"); 893 #else 894 f = fopen("/etc/motd", "r"); 895 #endif 896 if (f) { 897 while (fgets(buf, sizeof(buf), f)) 898 fputs(buf, stdout); 899 fclose(f); 900 } 901 } 902 } 903 904 905 /* 906 * Check for quiet login, either .hushlogin or command given. 907 */ 908 int 909 check_quietlogin(Session *s, const char *command) 910 { 911 char buf[256]; 912 struct passwd *pw = s->pw; 913 struct stat st; 914 915 /* Return 1 if .hushlogin exists or a command given. */ 916 if (command != NULL) 917 return 1; 918 snprintf(buf, sizeof(buf), "%.200s/.hushlogin", pw->pw_dir); 919 #ifdef HAVE_LOGIN_CAP 920 if (login_getcapbool(lc, "hushlogin", 0) || stat(buf, &st) >= 0) 921 return 1; 922 #else 923 if (stat(buf, &st) >= 0) 924 return 1; 925 #endif 926 return 0; 927 } 928 929 /* 930 * Sets the value of the given variable in the environment. If the variable 931 * already exists, its value is overridden. 932 */ 933 void 934 child_set_env(char ***envp, u_int *envsizep, const char *name, 935 const char *value) 936 { 937 char **env; 938 u_int envsize; 939 u_int i, namelen; 940 941 /* 942 * Find the slot where the value should be stored. If the variable 943 * already exists, we reuse the slot; otherwise we append a new slot 944 * at the end of the array, expanding if necessary. 945 */ 946 env = *envp; 947 namelen = strlen(name); 948 for (i = 0; env[i]; i++) 949 if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=') 950 break; 951 if (env[i]) { 952 /* Reuse the slot. */ 953 xfree(env[i]); 954 } else { 955 /* New variable. Expand if necessary. */ 956 envsize = *envsizep; 957 if (i >= envsize - 1) { 958 if (envsize >= 1000) 959 fatal("child_set_env: too many env vars"); 960 envsize += 50; 961 env = (*envp) = xrealloc(env, envsize, sizeof(char *)); 962 *envsizep = envsize; 963 } 964 /* Need to set the NULL pointer at end of array beyond the new slot. */ 965 env[i + 1] = NULL; 966 } 967 968 /* Allocate space and format the variable in the appropriate slot. */ 969 env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1); 970 snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value); 971 } 972 973 #ifdef HAVE_LOGIN_CAP 974 /* 975 * Sets any environment variables specified in login.conf. 976 * Taken from: 977 * NetBSD: login_cap.c,v 1.11 2001/07/22 13:34:01 wiz Exp 978 * Modified to use child_set_env instead of setenv. 979 */ 980 static void 981 lc_setuserenv(char ***env, u_int *envsize, login_cap_t *lc) 982 { 983 const char *stop = ", \t"; 984 int i, count; 985 char *ptr; 986 char **res; 987 char *str = login_getcapstr(lc, "setenv", NULL, NULL); 988 989 if (str == NULL || *str == '\0') 990 return; 991 992 /* count the sub-strings */ 993 for (i = 1, ptr = str; *ptr; i++) { 994 ptr += strcspn(ptr, stop); 995 if (*ptr) 996 ptr++; 997 } 998 999 /* allocate ptr array and string */ 1000 count = i; 1001 res = malloc(count * sizeof(char *) + strlen(str) + 1); 1002 1003 if (!res) 1004 return; 1005 1006 ptr = (char *)res + count * sizeof(char *); 1007 strcpy(ptr, str); 1008 1009 /* split string */ 1010 for (i = 0; *ptr && i < count; i++) { 1011 res[i] = ptr; 1012 ptr += strcspn(ptr, stop); 1013 if (*ptr) 1014 *ptr++ = '\0'; 1015 } 1016 1017 res[i] = NULL; 1018 1019 for (i = 0; i < count && res[i]; i++) { 1020 if (*res[i] != '\0') { 1021 if ((ptr = strchr(res[i], '=')) != NULL) 1022 *ptr++ = '\0'; 1023 else 1024 ptr = ""; 1025 child_set_env(env, envsize, res[i], ptr); 1026 } 1027 } 1028 1029 free(res); 1030 return; 1031 } 1032 #endif 1033 1034 /* 1035 * Reads environment variables from the given file and adds/overrides them 1036 * into the environment. If the file does not exist, this does nothing. 1037 * Otherwise, it must consist of empty lines, comments (line starts with '#') 1038 * and assignments of the form name=value. No other forms are allowed. 1039 */ 1040 static void 1041 read_environment_file(char ***env, u_int *envsize, 1042 const char *filename) 1043 { 1044 FILE *f; 1045 char buf[4096]; 1046 char *cp, *value; 1047 u_int lineno = 0; 1048 1049 f = fopen(filename, "r"); 1050 if (!f) 1051 return; 1052 1053 while (fgets(buf, sizeof(buf), f)) { 1054 if (++lineno > 1000) 1055 fatal("Too many lines in environment file %s", filename); 1056 for (cp = buf; *cp == ' ' || *cp == '\t'; cp++) 1057 ; 1058 if (!*cp || *cp == '#' || *cp == '\n') 1059 continue; 1060 1061 cp[strcspn(cp, "\n")] = '\0'; 1062 1063 value = strchr(cp, '='); 1064 if (value == NULL) { 1065 fprintf(stderr, "Bad line %u in %.100s\n", lineno, 1066 filename); 1067 continue; 1068 } 1069 /* 1070 * Replace the equals sign by nul, and advance value to 1071 * the value string. 1072 */ 1073 *value = '\0'; 1074 value++; 1075 child_set_env(env, envsize, cp, value); 1076 } 1077 fclose(f); 1078 } 1079 1080 #ifdef USE_PAM 1081 void copy_environment(char **, char ***, u_int *); 1082 void copy_environment(char **source, char ***env, u_int *envsize) 1083 { 1084 char *var_name, *var_val; 1085 int i; 1086 1087 if (source == NULL) 1088 return; 1089 1090 for (i = 0; source[i] != NULL; i++) { 1091 var_name = xstrdup(source[i]); 1092 if ((var_val = strstr(var_name, "=")) == NULL) { 1093 xfree(var_name); 1094 continue; 1095 } 1096 *var_val++ = '\0'; 1097 1098 debug3("Copy environment: %s=%s", var_name, var_val); 1099 child_set_env(env, envsize, var_name, var_val); 1100 1101 xfree(var_name); 1102 } 1103 } 1104 #endif 1105 1106 static char ** 1107 do_setup_env(Session *s, const char *shell) 1108 { 1109 char buf[256]; 1110 u_int i, envsize; 1111 char **env, *laddr; 1112 struct passwd *pw = s->pw; 1113 1114 /* Initialize the environment. */ 1115 envsize = 100; 1116 env = xcalloc(envsize, sizeof(char *)); 1117 env[0] = NULL; 1118 1119 #ifdef GSSAPI 1120 /* Allow any GSSAPI methods that we've used to alter 1121 * the childs environment as they see fit 1122 */ 1123 ssh_gssapi_do_child(&env, &envsize); 1124 #endif 1125 1126 if (!options.use_login) { 1127 #ifdef HAVE_LOGIN_CAP 1128 lc_setuserenv(&env, &envsize, lc); 1129 #endif 1130 /* Set basic environment. */ 1131 for (i = 0; i < s->num_env; i++) 1132 child_set_env(&env, &envsize, s->env[i].name, 1133 s->env[i].val); 1134 1135 child_set_env(&env, &envsize, "USER", pw->pw_name); 1136 child_set_env(&env, &envsize, "LOGNAME", pw->pw_name); 1137 child_set_env(&env, &envsize, "HOME", pw->pw_dir); 1138 #ifdef HAVE_LOGIN_CAP 1139 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETPATH) < 0) 1140 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); 1141 else 1142 child_set_env(&env, &envsize, "PATH", getenv("PATH")); 1143 #else 1144 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); 1145 #endif 1146 1147 snprintf(buf, sizeof buf, "%.200s/%.50s", 1148 _PATH_MAILDIR, pw->pw_name); 1149 child_set_env(&env, &envsize, "MAIL", buf); 1150 1151 /* Normal systems set SHELL by default. */ 1152 child_set_env(&env, &envsize, "SHELL", shell); 1153 } 1154 if (getenv("TZ")) 1155 child_set_env(&env, &envsize, "TZ", getenv("TZ")); 1156 1157 /* Set custom environment options from RSA authentication. */ 1158 if (!options.use_login) { 1159 while (custom_environment) { 1160 struct envstring *ce = custom_environment; 1161 char *str = ce->s; 1162 1163 for (i = 0; str[i] != '=' && str[i]; i++) 1164 ; 1165 if (str[i] == '=') { 1166 str[i] = 0; 1167 child_set_env(&env, &envsize, str, str + i + 1); 1168 } 1169 custom_environment = ce->next; 1170 xfree(ce->s); 1171 xfree(ce); 1172 } 1173 } 1174 1175 /* SSH_CLIENT deprecated */ 1176 snprintf(buf, sizeof buf, "%.50s %d %d", 1177 get_remote_ipaddr(), get_remote_port(), get_local_port()); 1178 child_set_env(&env, &envsize, "SSH_CLIENT", buf); 1179 1180 laddr = get_local_ipaddr(packet_get_connection_in()); 1181 snprintf(buf, sizeof buf, "%.50s %d %.50s %d", 1182 get_remote_ipaddr(), get_remote_port(), laddr, get_local_port()); 1183 xfree(laddr); 1184 child_set_env(&env, &envsize, "SSH_CONNECTION", buf); 1185 1186 if (s->ttyfd != -1) 1187 child_set_env(&env, &envsize, "SSH_TTY", s->tty); 1188 if (s->term) 1189 child_set_env(&env, &envsize, "TERM", s->term); 1190 if (s->display) 1191 child_set_env(&env, &envsize, "DISPLAY", s->display); 1192 if (original_command) 1193 child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND", 1194 original_command); 1195 #ifdef KRB4 1196 if (s->authctxt->krb4_ticket_file) 1197 child_set_env(&env, &envsize, "KRBTKFILE", 1198 s->authctxt->krb4_ticket_file); 1199 #endif 1200 #ifdef KRB5 1201 if (s->authctxt->krb5_ticket_file) 1202 child_set_env(&env, &envsize, "KRB5CCNAME", 1203 s->authctxt->krb5_ticket_file); 1204 #endif 1205 #ifdef USE_PAM 1206 /* 1207 * Pull in any environment variables that may have 1208 * been set by PAM. 1209 */ 1210 if (options.use_pam) { 1211 char **p; 1212 1213 p = fetch_pam_child_environment(); 1214 copy_environment(p, &env, &envsize); 1215 free_pam_environment(p); 1216 1217 p = fetch_pam_environment(); 1218 copy_environment(p, &env, &envsize); 1219 free_pam_environment(p); 1220 } 1221 #endif /* USE_PAM */ 1222 1223 if (auth_sock_name != NULL) 1224 child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME, 1225 auth_sock_name); 1226 1227 /* read $HOME/.ssh/environment. */ 1228 if (options.permit_user_env && !options.use_login) { 1229 snprintf(buf, sizeof buf, "%.200s/.ssh/environment", 1230 pw->pw_dir); 1231 read_environment_file(&env, &envsize, buf); 1232 } 1233 if (debug_flag) { 1234 /* dump the environment */ 1235 fprintf(stderr, "Environment:\n"); 1236 for (i = 0; env[i]; i++) 1237 fprintf(stderr, " %.200s\n", env[i]); 1238 } 1239 return env; 1240 } 1241 1242 /* 1243 * Run $HOME/.ssh/rc, /etc/ssh/sshrc, or xauth (whichever is found 1244 * first in this order). 1245 */ 1246 static void 1247 do_rc_files(Session *s, const char *shell) 1248 { 1249 FILE *f = NULL; 1250 char cmd[1024]; 1251 int do_xauth; 1252 struct stat st; 1253 1254 do_xauth = 1255 s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL; 1256 1257 /* ignore _PATH_SSH_USER_RC for subsystems and admin forced commands */ 1258 if (!s->is_subsystem && options.adm_forced_command == NULL && 1259 !no_user_rc && stat(_PATH_SSH_USER_RC, &st) >= 0) { 1260 snprintf(cmd, sizeof cmd, "%s -c '%s %s'", 1261 shell, _PATH_BSHELL, _PATH_SSH_USER_RC); 1262 if (debug_flag) 1263 fprintf(stderr, "Running %s\n", cmd); 1264 f = popen(cmd, "w"); 1265 if (f) { 1266 if (do_xauth) 1267 fprintf(f, "%s %s\n", s->auth_proto, 1268 s->auth_data); 1269 pclose(f); 1270 } else 1271 fprintf(stderr, "Could not run %s\n", 1272 _PATH_SSH_USER_RC); 1273 } else if (stat(_PATH_SSH_SYSTEM_RC, &st) >= 0) { 1274 if (debug_flag) 1275 fprintf(stderr, "Running %s %s\n", _PATH_BSHELL, 1276 _PATH_SSH_SYSTEM_RC); 1277 f = popen(_PATH_BSHELL " " _PATH_SSH_SYSTEM_RC, "w"); 1278 if (f) { 1279 if (do_xauth) 1280 fprintf(f, "%s %s\n", s->auth_proto, 1281 s->auth_data); 1282 pclose(f); 1283 } else 1284 fprintf(stderr, "Could not run %s\n", 1285 _PATH_SSH_SYSTEM_RC); 1286 } else if (do_xauth && options.xauth_location != NULL) { 1287 /* Add authority data to .Xauthority if appropriate. */ 1288 if (debug_flag) { 1289 fprintf(stderr, 1290 "Running %.500s remove %.100s\n", 1291 options.xauth_location, s->auth_display); 1292 fprintf(stderr, 1293 "%.500s add %.100s %.100s %.100s\n", 1294 options.xauth_location, s->auth_display, 1295 s->auth_proto, s->auth_data); 1296 } 1297 snprintf(cmd, sizeof cmd, "%s -q -", 1298 options.xauth_location); 1299 f = popen(cmd, "w"); 1300 if (f) { 1301 fprintf(f, "remove %s\n", 1302 s->auth_display); 1303 fprintf(f, "add %s %s %s\n", 1304 s->auth_display, s->auth_proto, 1305 s->auth_data); 1306 pclose(f); 1307 } else { 1308 fprintf(stderr, "Could not run %s\n", 1309 cmd); 1310 } 1311 } 1312 } 1313 1314 static void 1315 do_nologin(struct passwd *pw) 1316 { 1317 FILE *f = NULL; 1318 char buf[1024], *nl, *def_nl = _PATH_NOLOGIN; 1319 struct stat sb; 1320 1321 #ifdef HAVE_LOGIN_CAP 1322 if (login_getcapbool(lc, "ignorenologin", 0) && pw->pw_uid) 1323 return; 1324 nl = login_getcapstr(lc, "nologin", def_nl, def_nl); 1325 1326 if (stat(nl, &sb) == -1) { 1327 if (nl != def_nl) 1328 xfree(nl); 1329 return; 1330 } 1331 #else 1332 if (pw->pw_uid) 1333 nl = def_nl; 1334 #endif 1335 /* /etc/nologin exists. Print its contents if we can and exit. */ 1336 logit("User %.100s not allowed because %s exists", pw->pw_name, nl); 1337 if ((f = fopen(nl, "r")) != NULL) { 1338 while (fgets(buf, sizeof(buf), f)) 1339 fputs(buf, stderr); 1340 fclose(f); 1341 } 1342 exit(254); 1343 } 1344 1345 /* 1346 * Chroot into a directory after checking it for safety: all path components 1347 * must be root-owned directories with strict permissions. 1348 */ 1349 static void 1350 safely_chroot(const char *path, uid_t uid) 1351 { 1352 const char *cp; 1353 char component[MAXPATHLEN]; 1354 struct stat st; 1355 1356 if (*path != '/') 1357 fatal("chroot path does not begin at root"); 1358 if (strlen(path) >= sizeof(component)) 1359 fatal("chroot path too long"); 1360 1361 /* 1362 * Descend the path, checking that each component is a 1363 * root-owned directory with strict permissions. 1364 */ 1365 for (cp = path; cp != NULL;) { 1366 if ((cp = strchr(cp, '/')) == NULL) 1367 strlcpy(component, path, sizeof(component)); 1368 else { 1369 cp++; 1370 memcpy(component, path, cp - path); 1371 component[cp - path] = '\0'; 1372 } 1373 1374 debug3("%s: checking '%s'", __func__, component); 1375 1376 if (stat(component, &st) != 0) 1377 fatal("%s: stat(\"%s\"): %s", __func__, 1378 component, strerror(errno)); 1379 if (st.st_uid != 0 || (st.st_mode & 022) != 0) 1380 fatal("bad ownership or modes for chroot " 1381 "directory %s\"%s\"", 1382 cp == NULL ? "" : "component ", component); 1383 if (!S_ISDIR(st.st_mode)) 1384 fatal("chroot path %s\"%s\" is not a directory", 1385 cp == NULL ? "" : "component ", component); 1386 1387 } 1388 1389 if (chdir(path) == -1) 1390 fatal("Unable to chdir to chroot path \"%s\": " 1391 "%s", path, strerror(errno)); 1392 if (chroot(path) == -1) 1393 fatal("chroot(\"%s\"): %s", path, strerror(errno)); 1394 if (chdir("/") == -1) 1395 fatal("%s: chdir(/) after chroot: %s", 1396 __func__, strerror(errno)); 1397 verbose("Changed root directory to \"%s\"", path); 1398 } 1399 1400 /* Set login name, uid, gid, and groups. */ 1401 void 1402 do_setusercontext(struct passwd *pw) 1403 { 1404 char *chroot_path, *tmp; 1405 1406 if (getuid() == 0 || geteuid() == 0) { 1407 #ifdef HAVE_LOGIN_CAP 1408 # ifdef USE_PAM 1409 if (options.use_pam) { 1410 do_pam_setcred(use_privsep); 1411 } 1412 # endif /* USE_PAM */ 1413 /* Prepare groups */ 1414 if (setusercontext(lc, pw, pw->pw_uid, 1415 (LOGIN_SETALL & ~(LOGIN_SETPATH|LOGIN_SETUSER))) < 0) { 1416 perror("unable to set user context"); 1417 exit(1); 1418 } 1419 #else 1420 1421 if (setlogin(pw->pw_name) < 0) 1422 error("setlogin failed: %s", strerror(errno)); 1423 if (setgid(pw->pw_gid) < 0) { 1424 perror("setgid"); 1425 exit(1); 1426 } 1427 /* Initialize the group list. */ 1428 if (initgroups(pw->pw_name, pw->pw_gid) < 0) { 1429 perror("initgroups"); 1430 exit(1); 1431 } 1432 endgrent(); 1433 # ifdef USE_PAM 1434 /* 1435 * PAM credentials may take the form of supplementary groups. 1436 * These will have been wiped by the above initgroups() call. 1437 * Reestablish them here. 1438 */ 1439 if (options.use_pam) { 1440 do_pam_setcred(use_privsep); 1441 } 1442 # endif /* USE_PAM */ 1443 #endif 1444 if (options.chroot_directory != NULL && 1445 strcasecmp(options.chroot_directory, "none") != 0) { 1446 tmp = tilde_expand_filename(options.chroot_directory, 1447 pw->pw_uid); 1448 chroot_path = percent_expand(tmp, "h", pw->pw_dir, 1449 "u", pw->pw_name, (char *)NULL); 1450 safely_chroot(chroot_path, pw->pw_uid); 1451 free(tmp); 1452 free(chroot_path); 1453 } 1454 1455 #ifdef HAVE_LOGIN_CAP 1456 /* Set UID */ 1457 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUSER) < 0) { 1458 perror("unable to set user context (setuser)"); 1459 exit(1); 1460 } 1461 #else 1462 /* Permanently switch to the desired uid. */ 1463 permanently_set_uid(pw); 1464 #endif 1465 } 1466 if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) 1467 fatal("Failed to set uids to %u.", (u_int) pw->pw_uid); 1468 } 1469 1470 static void 1471 do_pwchange(Session *s) 1472 { 1473 fflush(NULL); 1474 fprintf(stderr, "WARNING: Your password has expired.\n"); 1475 if (s->ttyfd != -1) { 1476 fprintf(stderr, 1477 "You must change your password now and login again!\n"); 1478 execl(_PATH_PASSWD_PROG, "passwd", (char *)NULL); 1479 perror("passwd"); 1480 } else { 1481 fprintf(stderr, 1482 "Password change required but no TTY available.\n"); 1483 } 1484 exit(1); 1485 } 1486 1487 static void 1488 launch_login(struct passwd *pw, const char *hostname) 1489 { 1490 /* Launch login(1). */ 1491 1492 execl("/usr/bin/login", "login", "-h", hostname, 1493 "-p", "-f", "--", pw->pw_name, (char *)NULL); 1494 1495 /* Login couldn't be executed, die. */ 1496 1497 perror("login"); 1498 exit(1); 1499 } 1500 1501 static void 1502 child_close_fds(void) 1503 { 1504 int i; 1505 1506 if (packet_get_connection_in() == packet_get_connection_out()) 1507 close(packet_get_connection_in()); 1508 else { 1509 close(packet_get_connection_in()); 1510 close(packet_get_connection_out()); 1511 } 1512 /* 1513 * Close all descriptors related to channels. They will still remain 1514 * open in the parent. 1515 */ 1516 /* XXX better use close-on-exec? -markus */ 1517 channel_close_all(); 1518 1519 /* 1520 * Close any extra file descriptors. Note that there may still be 1521 * descriptors left by system functions. They will be closed later. 1522 */ 1523 endpwent(); 1524 1525 /* 1526 * Close any extra open file descriptors so that we don't have them 1527 * hanging around in clients. Note that we want to do this after 1528 * initgroups, because at least on Solaris 2.3 it leaves file 1529 * descriptors open. 1530 */ 1531 for (i = 3; i < 64; i++) 1532 close(i); 1533 } 1534 1535 /* 1536 * Performs common processing for the child, such as setting up the 1537 * environment, closing extra file descriptors, setting the user and group 1538 * ids, and executing the command or shell. 1539 */ 1540 #define ARGV_MAX 10 1541 void 1542 do_child(Session *s, const char *command) 1543 { 1544 extern char **environ; 1545 char **env; 1546 char *argv[ARGV_MAX]; 1547 const char *shell, *shell0, *hostname = NULL; 1548 struct passwd *pw = s->pw; 1549 int r = 0; 1550 1551 /* remove hostkey from the child's memory */ 1552 destroy_sensitive_data(); 1553 1554 /* Force a password change */ 1555 if (s->authctxt->force_pwchange) { 1556 do_setusercontext(pw); 1557 child_close_fds(); 1558 do_pwchange(s); 1559 exit(1); 1560 } 1561 1562 /* login(1) is only called if we execute the login shell */ 1563 if (options.use_login && command != NULL) 1564 options.use_login = 0; 1565 1566 /* 1567 * Login(1) does this as well, and it needs uid 0 for the "-h" 1568 * switch, so we let login(1) to this for us. 1569 */ 1570 if (!options.use_login) { 1571 do_nologin(pw); 1572 do_setusercontext(pw); 1573 /* 1574 * PAM session modules in do_setusercontext may have 1575 * generated messages, so if this in an interactive 1576 * login then display them too. 1577 */ 1578 if (!check_quietlogin(s, command)) 1579 display_loginmsg(); 1580 } 1581 #ifdef USE_PAM 1582 if (options.use_pam && !is_pam_session_open()) { 1583 debug3("PAM session not opened, exiting"); 1584 display_loginmsg(); 1585 exit(254); 1586 } 1587 #endif 1588 1589 /* 1590 * Get the shell from the password data. An empty shell field is 1591 * legal, and means /bin/sh. 1592 */ 1593 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; 1594 1595 /* 1596 * Make sure $SHELL points to the shell from the password file, 1597 * even if shell is overridden from login.conf 1598 */ 1599 env = do_setup_env(s, shell); 1600 1601 #ifdef HAVE_LOGIN_CAP 1602 shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell); 1603 #endif 1604 1605 /* we have to stash the hostname before we close our socket. */ 1606 if (options.use_login) 1607 hostname = get_remote_name_or_ip(utmp_len, 1608 options.use_dns); 1609 /* 1610 * Close the connection descriptors; note that this is the child, and 1611 * the server will still have the socket open, and it is important 1612 * that we do not shutdown it. Note that the descriptors cannot be 1613 * closed before building the environment, as we call 1614 * get_remote_ipaddr there. 1615 */ 1616 child_close_fds(); 1617 1618 /* 1619 * Must take new environment into use so that .ssh/rc, 1620 * /etc/ssh/sshrc and xauth are run in the proper environment. 1621 */ 1622 environ = env; 1623 1624 #ifdef KRB5 1625 /* 1626 * At this point, we check to see if AFS is active and if we have 1627 * a valid Kerberos 5 TGT. If so, it seems like a good idea to see 1628 * if we can (and need to) extend the ticket into an AFS token. If 1629 * we don't do this, we run into potential problems if the user's 1630 * home directory is in AFS and it's not world-readable. 1631 */ 1632 1633 if (options.kerberos_get_afs_token && k_hasafs() && 1634 (s->authctxt->krb5_ctx != NULL)) { 1635 char cell[64]; 1636 1637 debug("Getting AFS token"); 1638 1639 k_setpag(); 1640 1641 if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0) 1642 krb5_afslog(s->authctxt->krb5_ctx, 1643 s->authctxt->krb5_fwd_ccache, cell, NULL); 1644 1645 krb5_afslog_home(s->authctxt->krb5_ctx, 1646 s->authctxt->krb5_fwd_ccache, NULL, NULL, pw->pw_dir); 1647 } 1648 #endif 1649 1650 /* Change current directory to the user's home directory. */ 1651 if (chdir(pw->pw_dir) < 0) { 1652 /* Suppress missing homedir warning for chroot case */ 1653 r = login_getcapbool(lc, "requirehome", 0); 1654 if (r || options.chroot_directory == NULL || 1655 strcasecmp(options.chroot_directory, "none") == 0) 1656 fprintf(stderr, "Could not chdir to home " 1657 "directory %s: %s\n", pw->pw_dir, 1658 strerror(errno)); 1659 if (r) 1660 exit(1); 1661 } 1662 1663 closefrom(STDERR_FILENO + 1); 1664 1665 if (!options.use_login) 1666 do_rc_files(s, shell); 1667 1668 /* restore SIGPIPE for child */ 1669 signal(SIGPIPE, SIG_DFL); 1670 1671 if (s->is_subsystem == SUBSYSTEM_INT_SFTP_ERROR) { 1672 printf("This service allows sftp connections only.\n"); 1673 fflush(NULL); 1674 exit(1); 1675 } else if (s->is_subsystem == SUBSYSTEM_INT_SFTP) { 1676 extern int optind, optreset; 1677 int i; 1678 char *p, *args; 1679 1680 setproctitle("%s@%s", s->pw->pw_name, INTERNAL_SFTP_NAME); 1681 args = xstrdup(command ? command : "sftp-server"); 1682 for (i = 0, (p = strtok(args, " ")); p; (p = strtok(NULL, " "))) 1683 if (i < ARGV_MAX - 1) 1684 argv[i++] = p; 1685 argv[i] = NULL; 1686 optind = optreset = 1; 1687 __progname = argv[0]; 1688 exit(sftp_server_main(i, argv, s->pw)); 1689 } 1690 1691 fflush(NULL); 1692 1693 if (options.use_login) { 1694 launch_login(pw, hostname); 1695 /* NEVERREACHED */ 1696 } 1697 1698 /* Get the last component of the shell name. */ 1699 if ((shell0 = strrchr(shell, '/')) != NULL) 1700 shell0++; 1701 else 1702 shell0 = shell; 1703 1704 /* 1705 * If we have no command, execute the shell. In this case, the shell 1706 * name to be passed in argv[0] is preceded by '-' to indicate that 1707 * this is a login shell. 1708 */ 1709 if (!command) { 1710 char argv0[256]; 1711 1712 /* Start the shell. Set initial character to '-'. */ 1713 argv0[0] = '-'; 1714 1715 if (strlcpy(argv0 + 1, shell0, sizeof(argv0) - 1) 1716 >= sizeof(argv0) - 1) { 1717 errno = EINVAL; 1718 perror(shell); 1719 exit(1); 1720 } 1721 1722 /* Execute the shell. */ 1723 argv[0] = argv0; 1724 argv[1] = NULL; 1725 execve(shell, argv, env); 1726 1727 /* Executing the shell failed. */ 1728 perror(shell); 1729 exit(1); 1730 } 1731 /* 1732 * Execute the command using the user's shell. This uses the -c 1733 * option to execute the command. 1734 */ 1735 argv[0] = (char *) shell0; 1736 argv[1] = "-c"; 1737 argv[2] = (char *) command; 1738 argv[3] = NULL; 1739 execve(shell, argv, env); 1740 perror(shell); 1741 exit(1); 1742 } 1743 1744 void 1745 session_unused(int id) 1746 { 1747 debug3("%s: session id %d unused", __func__, id); 1748 if (id >= options.max_sessions || 1749 id >= sessions_nalloc) { 1750 fatal("%s: insane session id %d (max %d nalloc %d)", 1751 __func__, id, options.max_sessions, sessions_nalloc); 1752 } 1753 bzero(&sessions[id], sizeof(*sessions)); 1754 sessions[id].self = id; 1755 sessions[id].used = 0; 1756 sessions[id].chanid = -1; 1757 sessions[id].ptyfd = -1; 1758 sessions[id].ttyfd = -1; 1759 sessions[id].ptymaster = -1; 1760 sessions[id].x11_chanids = NULL; 1761 sessions[id].next_unused = sessions_first_unused; 1762 sessions_first_unused = id; 1763 } 1764 1765 Session * 1766 session_new(void) 1767 { 1768 Session *s, *tmp; 1769 1770 if (sessions_first_unused == -1) { 1771 if (sessions_nalloc >= options.max_sessions) 1772 return NULL; 1773 debug2("%s: allocate (allocated %d max %d)", 1774 __func__, sessions_nalloc, options.max_sessions); 1775 tmp = xrealloc(sessions, sessions_nalloc + 1, 1776 sizeof(*sessions)); 1777 if (tmp == NULL) { 1778 error("%s: cannot allocate %d sessions", 1779 __func__, sessions_nalloc + 1); 1780 return NULL; 1781 } 1782 sessions = tmp; 1783 session_unused(sessions_nalloc++); 1784 } 1785 1786 if (sessions_first_unused >= sessions_nalloc || 1787 sessions_first_unused < 0) { 1788 fatal("%s: insane first_unused %d max %d nalloc %d", 1789 __func__, sessions_first_unused, options.max_sessions, 1790 sessions_nalloc); 1791 } 1792 1793 s = &sessions[sessions_first_unused]; 1794 if (s->used) { 1795 fatal("%s: session %d already used", 1796 __func__, sessions_first_unused); 1797 } 1798 sessions_first_unused = s->next_unused; 1799 s->used = 1; 1800 s->next_unused = -1; 1801 debug("session_new: session %d", s->self); 1802 1803 return s; 1804 } 1805 1806 static void 1807 session_dump(void) 1808 { 1809 int i; 1810 for (i = 0; i < sessions_nalloc; i++) { 1811 Session *s = &sessions[i]; 1812 1813 debug("dump: used %d next_unused %d session %d %p " 1814 "channel %d pid %ld", 1815 s->used, 1816 s->next_unused, 1817 s->self, 1818 s, 1819 s->chanid, 1820 (long)s->pid); 1821 } 1822 } 1823 1824 int 1825 session_open(Authctxt *authctxt, int chanid) 1826 { 1827 Session *s = session_new(); 1828 debug("session_open: channel %d", chanid); 1829 if (s == NULL) { 1830 error("no more sessions"); 1831 return 0; 1832 } 1833 s->authctxt = authctxt; 1834 s->pw = authctxt->pw; 1835 if (s->pw == NULL || !authctxt->valid) 1836 fatal("no user for session %d", s->self); 1837 debug("session_open: session %d: link with channel %d", s->self, chanid); 1838 s->chanid = chanid; 1839 return 1; 1840 } 1841 1842 Session * 1843 session_by_tty(char *tty) 1844 { 1845 int i; 1846 for (i = 0; i < sessions_nalloc; i++) { 1847 Session *s = &sessions[i]; 1848 if (s->used && s->ttyfd != -1 && strcmp(s->tty, tty) == 0) { 1849 debug("session_by_tty: session %d tty %s", i, tty); 1850 return s; 1851 } 1852 } 1853 debug("session_by_tty: unknown tty %.100s", tty); 1854 session_dump(); 1855 return NULL; 1856 } 1857 1858 static Session * 1859 session_by_channel(int id) 1860 { 1861 int i; 1862 for (i = 0; i < sessions_nalloc; i++) { 1863 Session *s = &sessions[i]; 1864 if (s->used && s->chanid == id) { 1865 debug("session_by_channel: session %d channel %d", 1866 i, id); 1867 return s; 1868 } 1869 } 1870 debug("session_by_channel: unknown channel %d", id); 1871 session_dump(); 1872 return NULL; 1873 } 1874 1875 static Session * 1876 session_by_x11_channel(int id) 1877 { 1878 int i, j; 1879 1880 for (i = 0; i < sessions_nalloc; i++) { 1881 Session *s = &sessions[i]; 1882 1883 if (s->x11_chanids == NULL || !s->used) 1884 continue; 1885 for (j = 0; s->x11_chanids[j] != -1; j++) { 1886 if (s->x11_chanids[j] == id) { 1887 debug("session_by_x11_channel: session %d " 1888 "channel %d", s->self, id); 1889 return s; 1890 } 1891 } 1892 } 1893 debug("session_by_x11_channel: unknown channel %d", id); 1894 session_dump(); 1895 return NULL; 1896 } 1897 1898 static Session * 1899 session_by_pid(pid_t pid) 1900 { 1901 int i; 1902 debug("session_by_pid: pid %ld", (long)pid); 1903 for (i = 0; i < sessions_nalloc; i++) { 1904 Session *s = &sessions[i]; 1905 if (s->used && s->pid == pid) 1906 return s; 1907 } 1908 error("session_by_pid: unknown pid %ld", (long)pid); 1909 session_dump(); 1910 return NULL; 1911 } 1912 1913 static int 1914 session_window_change_req(Session *s) 1915 { 1916 s->col = packet_get_int(); 1917 s->row = packet_get_int(); 1918 s->xpixel = packet_get_int(); 1919 s->ypixel = packet_get_int(); 1920 packet_check_eom(); 1921 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 1922 return 1; 1923 } 1924 1925 static int 1926 session_pty_req(Session *s) 1927 { 1928 u_int len; 1929 int n_bytes; 1930 1931 if (no_pty_flag) { 1932 debug("Allocating a pty not permitted for this authentication."); 1933 return 0; 1934 } 1935 if (s->ttyfd != -1) { 1936 packet_disconnect("Protocol error: you already have a pty."); 1937 return 0; 1938 } 1939 1940 s->term = packet_get_string(&len); 1941 1942 if (compat20) { 1943 s->col = packet_get_int(); 1944 s->row = packet_get_int(); 1945 } else { 1946 s->row = packet_get_int(); 1947 s->col = packet_get_int(); 1948 } 1949 s->xpixel = packet_get_int(); 1950 s->ypixel = packet_get_int(); 1951 1952 if (strcmp(s->term, "") == 0) { 1953 xfree(s->term); 1954 s->term = NULL; 1955 } 1956 1957 /* Allocate a pty and open it. */ 1958 debug("Allocating pty."); 1959 if (!PRIVSEP(pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, 1960 sizeof(s->tty)))) { 1961 if (s->term) 1962 xfree(s->term); 1963 s->term = NULL; 1964 s->ptyfd = -1; 1965 s->ttyfd = -1; 1966 error("session_pty_req: session %d alloc failed", s->self); 1967 return 0; 1968 } 1969 debug("session_pty_req: session %d alloc %s", s->self, s->tty); 1970 1971 /* for SSH1 the tty modes length is not given */ 1972 if (!compat20) 1973 n_bytes = packet_remaining(); 1974 tty_parse_modes(s->ttyfd, &n_bytes); 1975 1976 if (!use_privsep) 1977 pty_setowner(s->pw, s->tty); 1978 1979 /* Set window size from the packet. */ 1980 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 1981 1982 packet_check_eom(); 1983 session_proctitle(s); 1984 return 1; 1985 } 1986 1987 static int 1988 session_subsystem_req(Session *s) 1989 { 1990 struct stat st; 1991 u_int len; 1992 int success = 0; 1993 char *prog, *cmd, *subsys = packet_get_string(&len); 1994 u_int i; 1995 1996 packet_check_eom(); 1997 logit("subsystem request for %.100s by user %s", subsys, 1998 s->pw->pw_name); 1999 2000 for (i = 0; i < options.num_subsystems; i++) { 2001 if (strcmp(subsys, options.subsystem_name[i]) == 0) { 2002 prog = options.subsystem_command[i]; 2003 cmd = options.subsystem_args[i]; 2004 if (strcmp(INTERNAL_SFTP_NAME, prog) == 0) { 2005 s->is_subsystem = SUBSYSTEM_INT_SFTP; 2006 debug("subsystem: %s", prog); 2007 } else { 2008 if (stat(prog, &st) < 0) 2009 debug("subsystem: cannot stat %s: %s", 2010 prog, strerror(errno)); 2011 s->is_subsystem = SUBSYSTEM_EXT; 2012 debug("subsystem: exec() %s", cmd); 2013 } 2014 success = do_exec(s, cmd) == 0; 2015 break; 2016 } 2017 } 2018 2019 if (!success) 2020 logit("subsystem request for %.100s failed, subsystem not found", 2021 subsys); 2022 2023 xfree(subsys); 2024 return success; 2025 } 2026 2027 static int 2028 session_x11_req(Session *s) 2029 { 2030 int success; 2031 2032 if (s->auth_proto != NULL || s->auth_data != NULL) { 2033 error("session_x11_req: session %d: " 2034 "x11 forwarding already active", s->self); 2035 return 0; 2036 } 2037 s->single_connection = packet_get_char(); 2038 s->auth_proto = packet_get_string(NULL); 2039 s->auth_data = packet_get_string(NULL); 2040 s->screen = packet_get_int(); 2041 packet_check_eom(); 2042 2043 success = session_setup_x11fwd(s); 2044 if (!success) { 2045 xfree(s->auth_proto); 2046 xfree(s->auth_data); 2047 s->auth_proto = NULL; 2048 s->auth_data = NULL; 2049 } 2050 return success; 2051 } 2052 2053 static int 2054 session_shell_req(Session *s) 2055 { 2056 packet_check_eom(); 2057 return do_exec(s, NULL) == 0; 2058 } 2059 2060 static int 2061 session_exec_req(Session *s) 2062 { 2063 u_int len, success; 2064 2065 char *command = packet_get_string(&len); 2066 packet_check_eom(); 2067 success = do_exec(s, command) == 0; 2068 xfree(command); 2069 return success; 2070 } 2071 2072 static int 2073 session_break_req(Session *s) 2074 { 2075 2076 packet_get_int(); /* ignored */ 2077 packet_check_eom(); 2078 2079 if (s->ttyfd == -1 || tcsendbreak(s->ttyfd, 0) < 0) 2080 return 0; 2081 return 1; 2082 } 2083 2084 static int 2085 session_env_req(Session *s) 2086 { 2087 char *name, *val; 2088 u_int name_len, val_len, i; 2089 2090 name = packet_get_string(&name_len); 2091 val = packet_get_string(&val_len); 2092 packet_check_eom(); 2093 2094 /* Don't set too many environment variables */ 2095 if (s->num_env > 128) { 2096 debug2("Ignoring env request %s: too many env vars", name); 2097 goto fail; 2098 } 2099 2100 for (i = 0; i < options.num_accept_env; i++) { 2101 if (match_pattern(name, options.accept_env[i])) { 2102 debug2("Setting env %d: %s=%s", s->num_env, name, val); 2103 s->env = xrealloc(s->env, s->num_env + 1, 2104 sizeof(*s->env)); 2105 s->env[s->num_env].name = name; 2106 s->env[s->num_env].val = val; 2107 s->num_env++; 2108 return (1); 2109 } 2110 } 2111 debug2("Ignoring env request %s: disallowed name", name); 2112 2113 fail: 2114 xfree(name); 2115 xfree(val); 2116 return (0); 2117 } 2118 2119 static int 2120 session_auth_agent_req(Session *s) 2121 { 2122 static int called = 0; 2123 packet_check_eom(); 2124 if (no_agent_forwarding_flag || !options.allow_agent_forwarding) { 2125 debug("session_auth_agent_req: no_agent_forwarding_flag"); 2126 return 0; 2127 } 2128 if (called) { 2129 return 0; 2130 } else { 2131 called = 1; 2132 return auth_input_request_forwarding(s->pw); 2133 } 2134 } 2135 2136 int 2137 session_input_channel_req(Channel *c, const char *rtype) 2138 { 2139 int success = 0; 2140 Session *s; 2141 2142 if ((s = session_by_channel(c->self)) == NULL) { 2143 logit("session_input_channel_req: no session %d req %.100s", 2144 c->self, rtype); 2145 return 0; 2146 } 2147 debug("session_input_channel_req: session %d req %s", s->self, rtype); 2148 2149 /* 2150 * a session is in LARVAL state until a shell, a command 2151 * or a subsystem is executed 2152 */ 2153 if (c->type == SSH_CHANNEL_LARVAL) { 2154 if (strcmp(rtype, "shell") == 0) { 2155 success = session_shell_req(s); 2156 } else if (strcmp(rtype, "exec") == 0) { 2157 success = session_exec_req(s); 2158 } else if (strcmp(rtype, "pty-req") == 0) { 2159 success = session_pty_req(s); 2160 } else if (strcmp(rtype, "x11-req") == 0) { 2161 success = session_x11_req(s); 2162 } else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) { 2163 success = session_auth_agent_req(s); 2164 } else if (strcmp(rtype, "subsystem") == 0) { 2165 success = session_subsystem_req(s); 2166 } else if (strcmp(rtype, "env") == 0) { 2167 success = session_env_req(s); 2168 } 2169 } 2170 if (strcmp(rtype, "window-change") == 0) { 2171 success = session_window_change_req(s); 2172 } else if (strcmp(rtype, "break") == 0) { 2173 success = session_break_req(s); 2174 } 2175 2176 return success; 2177 } 2178 2179 void 2180 session_set_fds(Session *s, int fdin, int fdout, int fderr, int ignore_fderr, 2181 int is_tty) 2182 { 2183 if (!compat20) 2184 fatal("session_set_fds: called for proto != 2.0"); 2185 /* 2186 * now that have a child and a pipe to the child, 2187 * we can activate our channel and register the fd's 2188 */ 2189 if (s->chanid == -1) 2190 fatal("no channel for session %d", s->self); 2191 if(options.hpn_disabled) 2192 channel_set_fds(s->chanid, 2193 fdout, fdin, fderr, 2194 ignore_fderr ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ, 2195 1, is_tty, CHAN_SES_WINDOW_DEFAULT); 2196 else 2197 channel_set_fds(s->chanid, 2198 fdout, fdin, fderr, 2199 ignore_fderr ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ, 2200 1, is_tty, options.hpn_buffer_size); 2201 } 2202 2203 /* 2204 * Function to perform pty cleanup. Also called if we get aborted abnormally 2205 * (e.g., due to a dropped connection). 2206 */ 2207 void 2208 session_pty_cleanup2(Session *s) 2209 { 2210 if (s == NULL) { 2211 error("session_pty_cleanup: no session"); 2212 return; 2213 } 2214 if (s->ttyfd == -1) 2215 return; 2216 2217 debug("session_pty_cleanup: session %d release %s", s->self, s->tty); 2218 2219 /* Record that the user has logged out. */ 2220 if (s->pid != 0) 2221 record_logout(s->pid, s->tty); 2222 2223 /* Release the pseudo-tty. */ 2224 if (getuid() == 0) 2225 pty_release(s->tty); 2226 2227 /* 2228 * Close the server side of the socket pairs. We must do this after 2229 * the pty cleanup, so that another process doesn't get this pty 2230 * while we're still cleaning up. 2231 */ 2232 if (s->ptymaster != -1 && close(s->ptymaster) < 0) 2233 error("close(s->ptymaster/%d): %s", 2234 s->ptymaster, strerror(errno)); 2235 2236 /* unlink pty from session */ 2237 s->ttyfd = -1; 2238 } 2239 2240 void 2241 session_pty_cleanup(Session *s) 2242 { 2243 PRIVSEP(session_pty_cleanup2(s)); 2244 } 2245 2246 static char * 2247 sig2name(int sig) 2248 { 2249 #define SSH_SIG(x) if (sig == SIG ## x) return #x 2250 SSH_SIG(ABRT); 2251 SSH_SIG(ALRM); 2252 SSH_SIG(FPE); 2253 SSH_SIG(HUP); 2254 SSH_SIG(ILL); 2255 SSH_SIG(INT); 2256 SSH_SIG(KILL); 2257 SSH_SIG(PIPE); 2258 SSH_SIG(QUIT); 2259 SSH_SIG(SEGV); 2260 SSH_SIG(TERM); 2261 SSH_SIG(USR1); 2262 SSH_SIG(USR2); 2263 #undef SSH_SIG 2264 return "SIG@openssh.com"; 2265 } 2266 2267 static void 2268 session_close_x11(int id) 2269 { 2270 Channel *c; 2271 2272 if ((c = channel_by_id(id)) == NULL) { 2273 debug("session_close_x11: x11 channel %d missing", id); 2274 } else { 2275 /* Detach X11 listener */ 2276 debug("session_close_x11: detach x11 channel %d", id); 2277 channel_cancel_cleanup(id); 2278 if (c->ostate != CHAN_OUTPUT_CLOSED) 2279 chan_mark_dead(c); 2280 } 2281 } 2282 2283 static void 2284 session_close_single_x11(int id, void *arg) 2285 { 2286 Session *s; 2287 u_int i; 2288 2289 debug3("session_close_single_x11: channel %d", id); 2290 channel_cancel_cleanup(id); 2291 if ((s = session_by_x11_channel(id)) == NULL) 2292 fatal("session_close_single_x11: no x11 channel %d", id); 2293 for (i = 0; s->x11_chanids[i] != -1; i++) { 2294 debug("session_close_single_x11: session %d: " 2295 "closing channel %d", s->self, s->x11_chanids[i]); 2296 /* 2297 * The channel "id" is already closing, but make sure we 2298 * close all of its siblings. 2299 */ 2300 if (s->x11_chanids[i] != id) 2301 session_close_x11(s->x11_chanids[i]); 2302 } 2303 xfree(s->x11_chanids); 2304 s->x11_chanids = NULL; 2305 if (s->display) { 2306 xfree(s->display); 2307 s->display = NULL; 2308 } 2309 if (s->auth_proto) { 2310 xfree(s->auth_proto); 2311 s->auth_proto = NULL; 2312 } 2313 if (s->auth_data) { 2314 xfree(s->auth_data); 2315 s->auth_data = NULL; 2316 } 2317 if (s->auth_display) { 2318 xfree(s->auth_display); 2319 s->auth_display = NULL; 2320 } 2321 } 2322 2323 static void 2324 session_exit_message(Session *s, int status) 2325 { 2326 Channel *c; 2327 2328 if ((c = channel_lookup(s->chanid)) == NULL) 2329 fatal("session_exit_message: session %d: no channel %d", 2330 s->self, s->chanid); 2331 debug("session_exit_message: session %d channel %d pid %ld", 2332 s->self, s->chanid, (long)s->pid); 2333 2334 if (WIFEXITED(status)) { 2335 channel_request_start(s->chanid, "exit-status", 0); 2336 packet_put_int(WEXITSTATUS(status)); 2337 packet_send(); 2338 } else if (WIFSIGNALED(status)) { 2339 channel_request_start(s->chanid, "exit-signal", 0); 2340 packet_put_cstring(sig2name(WTERMSIG(status))); 2341 packet_put_char(WCOREDUMP(status)? 1 : 0); 2342 packet_put_cstring(""); 2343 packet_put_cstring(""); 2344 packet_send(); 2345 } else { 2346 /* Some weird exit cause. Just exit. */ 2347 packet_disconnect("wait returned status %04x.", status); 2348 } 2349 2350 /* disconnect channel */ 2351 debug("session_exit_message: release channel %d", s->chanid); 2352 2353 /* 2354 * Adjust cleanup callback attachment to send close messages when 2355 * the channel gets EOF. The session will be then be closed 2356 * by session_close_by_channel when the childs close their fds. 2357 */ 2358 channel_register_cleanup(c->self, session_close_by_channel, 1); 2359 2360 /* 2361 * emulate a write failure with 'chan_write_failed', nobody will be 2362 * interested in data we write. 2363 * Note that we must not call 'chan_read_failed', since there could 2364 * be some more data waiting in the pipe. 2365 */ 2366 if (c->ostate != CHAN_OUTPUT_CLOSED) 2367 chan_write_failed(c); 2368 } 2369 2370 void 2371 session_close(Session *s) 2372 { 2373 u_int i; 2374 2375 debug("session_close: session %d pid %ld", s->self, (long)s->pid); 2376 if (s->ttyfd != -1) 2377 session_pty_cleanup(s); 2378 if (s->term) 2379 xfree(s->term); 2380 if (s->display) 2381 xfree(s->display); 2382 if (s->x11_chanids) 2383 xfree(s->x11_chanids); 2384 if (s->auth_display) 2385 xfree(s->auth_display); 2386 if (s->auth_data) 2387 xfree(s->auth_data); 2388 if (s->auth_proto) 2389 xfree(s->auth_proto); 2390 if (s->env != NULL) { 2391 for (i = 0; i < s->num_env; i++) { 2392 xfree(s->env[i].name); 2393 xfree(s->env[i].val); 2394 } 2395 xfree(s->env); 2396 } 2397 session_proctitle(s); 2398 session_unused(s->self); 2399 } 2400 2401 void 2402 session_close_by_pid(pid_t pid, int status) 2403 { 2404 Session *s = session_by_pid(pid); 2405 if (s == NULL) { 2406 debug("session_close_by_pid: no session for pid %ld", 2407 (long)pid); 2408 return; 2409 } 2410 if (s->chanid != -1) 2411 session_exit_message(s, status); 2412 if (s->ttyfd != -1) 2413 session_pty_cleanup(s); 2414 s->pid = 0; 2415 } 2416 2417 /* 2418 * this is called when a channel dies before 2419 * the session 'child' itself dies 2420 */ 2421 void 2422 session_close_by_channel(int id, void *arg) 2423 { 2424 Session *s = session_by_channel(id); 2425 u_int i; 2426 2427 if (s == NULL) { 2428 debug("session_close_by_channel: no session for id %d", id); 2429 return; 2430 } 2431 debug("session_close_by_channel: channel %d child %ld", 2432 id, (long)s->pid); 2433 if (s->pid != 0) { 2434 debug("session_close_by_channel: channel %d: has child", id); 2435 /* 2436 * delay detach of session, but release pty, since 2437 * the fd's to the child are already closed 2438 */ 2439 if (s->ttyfd != -1) 2440 session_pty_cleanup(s); 2441 return; 2442 } 2443 /* detach by removing callback */ 2444 channel_cancel_cleanup(s->chanid); 2445 2446 /* Close any X11 listeners associated with this session */ 2447 if (s->x11_chanids != NULL) { 2448 for (i = 0; s->x11_chanids[i] != -1; i++) { 2449 session_close_x11(s->x11_chanids[i]); 2450 s->x11_chanids[i] = -1; 2451 } 2452 } 2453 2454 s->chanid = -1; 2455 session_close(s); 2456 } 2457 2458 void 2459 session_destroy_all(void (*closefunc)(Session *)) 2460 { 2461 int i; 2462 for (i = 0; i < sessions_nalloc; i++) { 2463 Session *s = &sessions[i]; 2464 if (s->used) { 2465 if (closefunc != NULL) 2466 closefunc(s); 2467 else 2468 session_close(s); 2469 } 2470 } 2471 } 2472 2473 static char * 2474 session_tty_list(void) 2475 { 2476 static char buf[1024]; 2477 int i; 2478 buf[0] = '\0'; 2479 for (i = 0; i < sessions_nalloc; i++) { 2480 Session *s = &sessions[i]; 2481 if (s->used && s->ttyfd != -1) { 2482 char *p; 2483 if (buf[0] != '\0') 2484 strlcat(buf, ",", sizeof buf); 2485 if ((p = strstr(s->tty, "/pts/")) != NULL) 2486 p++; 2487 else { 2488 if ((p = strrchr(s->tty, '/')) != NULL) 2489 p++; 2490 else 2491 p = s->tty; 2492 } 2493 strlcat(buf, p, sizeof buf); 2494 } 2495 } 2496 if (buf[0] == '\0') 2497 strlcpy(buf, "notty", sizeof buf); 2498 return buf; 2499 } 2500 2501 void 2502 session_proctitle(Session *s) 2503 { 2504 if (s->pw == NULL) 2505 error("no user for session %d", s->self); 2506 else 2507 setproctitle("%s@%s", s->pw->pw_name, session_tty_list()); 2508 } 2509 2510 int 2511 session_setup_x11fwd(Session *s) 2512 { 2513 struct stat st; 2514 char display[512], auth_display[512]; 2515 char hostname[MAXHOSTNAMELEN]; 2516 u_int i; 2517 2518 if (no_x11_forwarding_flag) { 2519 packet_send_debug("X11 forwarding disabled in user configuration file."); 2520 return 0; 2521 } 2522 if (!options.x11_forwarding) { 2523 debug("X11 forwarding disabled in server configuration file."); 2524 return 0; 2525 } 2526 if (!options.xauth_location || 2527 (stat(options.xauth_location, &st) == -1)) { 2528 packet_send_debug("No xauth program; cannot forward with spoofing."); 2529 return 0; 2530 } 2531 if (options.use_login) { 2532 packet_send_debug("X11 forwarding disabled; " 2533 "not compatible with UseLogin=yes."); 2534 return 0; 2535 } 2536 if (s->display != NULL) { 2537 debug("X11 display already set."); 2538 return 0; 2539 } 2540 if (x11_create_display_inet(options.x11_display_offset, 2541 options.x11_use_localhost, s->single_connection, 2542 &s->display_number, &s->x11_chanids) == -1) { 2543 debug("x11_create_display_inet failed."); 2544 return 0; 2545 } 2546 for (i = 0; s->x11_chanids[i] != -1; i++) { 2547 channel_register_cleanup(s->x11_chanids[i], 2548 session_close_single_x11, 0); 2549 } 2550 2551 /* Set up a suitable value for the DISPLAY variable. */ 2552 if (gethostname(hostname, sizeof(hostname)) < 0) 2553 fatal("gethostname: %.100s", strerror(errno)); 2554 /* 2555 * auth_display must be used as the displayname when the 2556 * authorization entry is added with xauth(1). This will be 2557 * different than the DISPLAY string for localhost displays. 2558 */ 2559 if (options.x11_use_localhost) { 2560 snprintf(display, sizeof display, "localhost:%u.%u", 2561 s->display_number, s->screen); 2562 snprintf(auth_display, sizeof auth_display, "unix:%u.%u", 2563 s->display_number, s->screen); 2564 s->display = xstrdup(display); 2565 s->auth_display = xstrdup(auth_display); 2566 } else { 2567 snprintf(display, sizeof display, "%.400s:%u.%u", hostname, 2568 s->display_number, s->screen); 2569 s->display = xstrdup(display); 2570 s->auth_display = xstrdup(display); 2571 } 2572 2573 return 1; 2574 } 2575 2576 static void 2577 do_authenticated2(Authctxt *authctxt) 2578 { 2579 server_loop2(authctxt); 2580 } 2581 2582 void 2583 do_cleanup(Authctxt *authctxt) 2584 { 2585 static int called = 0; 2586 2587 debug("do_cleanup"); 2588 2589 /* no cleanup if we're in the child for login shell */ 2590 if (is_child) 2591 return; 2592 2593 /* avoid double cleanup */ 2594 if (called) 2595 return; 2596 called = 1; 2597 2598 if (authctxt == NULL || !authctxt->authenticated) 2599 return; 2600 #ifdef KRB4 2601 if (options.kerberos_ticket_cleanup) 2602 krb4_cleanup_proc(authctxt); 2603 #endif 2604 #ifdef KRB5 2605 if (options.kerberos_ticket_cleanup && 2606 authctxt->krb5_ctx) 2607 krb5_cleanup_proc(authctxt); 2608 #endif 2609 2610 #ifdef GSSAPI 2611 if (compat20 && options.gss_cleanup_creds) 2612 ssh_gssapi_cleanup_creds(); 2613 #endif 2614 2615 #ifdef USE_PAM 2616 if (options.use_pam) { 2617 sshpam_cleanup(); 2618 sshpam_thread_cleanup(); 2619 } 2620 #endif 2621 2622 /* remove agent socket */ 2623 auth_sock_cleanup_proc(authctxt->pw); 2624 2625 /* 2626 * Cleanup ptys/utmp only if privsep is disabled, 2627 * or if running in monitor. 2628 */ 2629 if (!use_privsep || mm_is_monitor()) 2630 session_destroy_all(session_pty_cleanup2); 2631 } 2632