1 /* $OpenBSD: session.c,v 1.280 2016/02/16 03:37:48 djm Exp $ */ 2 /* 3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 4 * All rights reserved 5 * 6 * As far as I am concerned, the code I have written for this software 7 * can be used freely for any purpose. Any derived versions of this 8 * software must be clearly marked as such, and if the derived work is 9 * incompatible with the protocol description in the RFC file, it must be 10 * called by a name other than "ssh" or "Secure Shell". 11 * 12 * SSH2 support by Markus Friedl. 13 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 14 * 15 * Redistribution and use in source and binary forms, with or without 16 * modification, are permitted provided that the following conditions 17 * are met: 18 * 1. Redistributions of source code must retain the above copyright 19 * notice, this list of conditions and the following disclaimer. 20 * 2. Redistributions in binary form must reproduce the above copyright 21 * notice, this list of conditions and the following disclaimer in the 22 * documentation and/or other materials provided with the distribution. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 25 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 26 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 27 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 28 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 29 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 30 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 31 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 32 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 33 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 34 */ 35 36 #include "includes.h" 37 __RCSID("$FreeBSD$"); 38 39 #include <sys/types.h> 40 #include <sys/param.h> 41 #ifdef HAVE_SYS_STAT_H 42 # include <sys/stat.h> 43 #endif 44 #include <sys/socket.h> 45 #include <sys/un.h> 46 #include <sys/wait.h> 47 48 #include <arpa/inet.h> 49 50 #include <ctype.h> 51 #include <errno.h> 52 #include <fcntl.h> 53 #include <grp.h> 54 #include <netdb.h> 55 #ifdef HAVE_PATHS_H 56 #include <paths.h> 57 #endif 58 #include <pwd.h> 59 #include <signal.h> 60 #include <stdarg.h> 61 #include <stdio.h> 62 #include <stdlib.h> 63 #include <string.h> 64 #include <unistd.h> 65 #include <limits.h> 66 67 #include "openbsd-compat/sys-queue.h" 68 #include "xmalloc.h" 69 #include "ssh.h" 70 #include "ssh1.h" 71 #include "ssh2.h" 72 #include "sshpty.h" 73 #include "packet.h" 74 #include "buffer.h" 75 #include "match.h" 76 #include "uidswap.h" 77 #include "compat.h" 78 #include "channels.h" 79 #include "key.h" 80 #include "cipher.h" 81 #ifdef GSSAPI 82 #include "ssh-gss.h" 83 #endif 84 #include "hostfile.h" 85 #include "auth.h" 86 #include "auth-options.h" 87 #include "authfd.h" 88 #include "pathnames.h" 89 #include "log.h" 90 #include "misc.h" 91 #include "servconf.h" 92 #include "sshlogin.h" 93 #include "serverloop.h" 94 #include "canohost.h" 95 #include "session.h" 96 #include "kex.h" 97 #include "monitor_wrap.h" 98 #include "sftp.h" 99 100 #if defined(KRB5) && defined(USE_AFS) 101 #include <kafs.h> 102 #endif 103 104 #ifdef WITH_SELINUX 105 #include <selinux/selinux.h> 106 #endif 107 108 #define IS_INTERNAL_SFTP(c) \ 109 (!strncmp(c, INTERNAL_SFTP_NAME, sizeof(INTERNAL_SFTP_NAME) - 1) && \ 110 (c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\0' || \ 111 c[sizeof(INTERNAL_SFTP_NAME) - 1] == ' ' || \ 112 c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\t')) 113 114 /* func */ 115 116 Session *session_new(void); 117 void session_set_fds(Session *, int, int, int, int, int); 118 void session_pty_cleanup(Session *); 119 void session_proctitle(Session *); 120 int session_setup_x11fwd(Session *); 121 int do_exec_pty(Session *, const char *); 122 int do_exec_no_pty(Session *, const char *); 123 int do_exec(Session *, const char *); 124 void do_login(Session *, const char *); 125 #ifdef LOGIN_NEEDS_UTMPX 126 static void do_pre_login(Session *s); 127 #endif 128 void do_child(Session *, const char *); 129 void do_motd(void); 130 int check_quietlogin(Session *, const char *); 131 132 static void do_authenticated1(Authctxt *); 133 static void do_authenticated2(Authctxt *); 134 135 static int session_pty_req(Session *); 136 137 /* import */ 138 extern ServerOptions options; 139 extern char *__progname; 140 extern int log_stderr; 141 extern int debug_flag; 142 extern u_int utmp_len; 143 extern int startup_pipe; 144 extern void destroy_sensitive_data(void); 145 extern Buffer loginmsg; 146 147 /* original command from peer. */ 148 const char *original_command = NULL; 149 150 /* data */ 151 static int sessions_first_unused = -1; 152 static int sessions_nalloc = 0; 153 static Session *sessions = NULL; 154 155 #define SUBSYSTEM_NONE 0 156 #define SUBSYSTEM_EXT 1 157 #define SUBSYSTEM_INT_SFTP 2 158 #define SUBSYSTEM_INT_SFTP_ERROR 3 159 160 #ifdef HAVE_LOGIN_CAP 161 login_cap_t *lc; 162 #endif 163 164 static int is_child = 0; 165 static int in_chroot = 0; 166 167 /* Name and directory of socket for authentication agent forwarding. */ 168 static char *auth_sock_name = NULL; 169 static char *auth_sock_dir = NULL; 170 171 /* removes the agent forwarding socket */ 172 173 static void 174 auth_sock_cleanup_proc(struct passwd *pw) 175 { 176 if (auth_sock_name != NULL) { 177 temporarily_use_uid(pw); 178 unlink(auth_sock_name); 179 rmdir(auth_sock_dir); 180 auth_sock_name = NULL; 181 restore_uid(); 182 } 183 } 184 185 static int 186 auth_input_request_forwarding(struct passwd * pw) 187 { 188 Channel *nc; 189 int sock = -1; 190 191 if (auth_sock_name != NULL) { 192 error("authentication forwarding requested twice."); 193 return 0; 194 } 195 196 /* Temporarily drop privileged uid for mkdir/bind. */ 197 temporarily_use_uid(pw); 198 199 /* Allocate a buffer for the socket name, and format the name. */ 200 auth_sock_dir = xstrdup("/tmp/ssh-XXXXXXXXXX"); 201 202 /* Create private directory for socket */ 203 if (mkdtemp(auth_sock_dir) == NULL) { 204 packet_send_debug("Agent forwarding disabled: " 205 "mkdtemp() failed: %.100s", strerror(errno)); 206 restore_uid(); 207 free(auth_sock_dir); 208 auth_sock_dir = NULL; 209 goto authsock_err; 210 } 211 212 xasprintf(&auth_sock_name, "%s/agent.%ld", 213 auth_sock_dir, (long) getpid()); 214 215 /* Start a Unix listener on auth_sock_name. */ 216 sock = unix_listener(auth_sock_name, SSH_LISTEN_BACKLOG, 0); 217 218 /* Restore the privileged uid. */ 219 restore_uid(); 220 221 /* Check for socket/bind/listen failure. */ 222 if (sock < 0) 223 goto authsock_err; 224 225 /* Allocate a channel for the authentication agent socket. */ 226 nc = channel_new("auth socket", 227 SSH_CHANNEL_AUTH_SOCKET, sock, sock, -1, 228 CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 229 0, "auth socket", 1); 230 nc->path = xstrdup(auth_sock_name); 231 return 1; 232 233 authsock_err: 234 free(auth_sock_name); 235 if (auth_sock_dir != NULL) { 236 rmdir(auth_sock_dir); 237 free(auth_sock_dir); 238 } 239 if (sock != -1) 240 close(sock); 241 auth_sock_name = NULL; 242 auth_sock_dir = NULL; 243 return 0; 244 } 245 246 static void 247 display_loginmsg(void) 248 { 249 if (buffer_len(&loginmsg) > 0) { 250 buffer_append(&loginmsg, "\0", 1); 251 printf("%s", (char *)buffer_ptr(&loginmsg)); 252 buffer_clear(&loginmsg); 253 } 254 } 255 256 void 257 do_authenticated(Authctxt *authctxt) 258 { 259 setproctitle("%s", authctxt->pw->pw_name); 260 261 /* setup the channel layer */ 262 /* XXX - streamlocal? */ 263 if (no_port_forwarding_flag || 264 (options.allow_tcp_forwarding & FORWARD_LOCAL) == 0) 265 channel_disable_adm_local_opens(); 266 else 267 channel_permit_all_opens(); 268 269 auth_debug_send(); 270 271 if (compat20) 272 do_authenticated2(authctxt); 273 else 274 do_authenticated1(authctxt); 275 276 do_cleanup(authctxt); 277 } 278 279 /* Check untrusted xauth strings for metacharacters */ 280 static int 281 xauth_valid_string(const char *s) 282 { 283 size_t i; 284 285 for (i = 0; s[i] != '\0'; i++) { 286 if (!isalnum((u_char)s[i]) && 287 s[i] != '.' && s[i] != ':' && s[i] != '/' && 288 s[i] != '-' && s[i] != '_') 289 return 0; 290 } 291 return 1; 292 } 293 294 /* 295 * Prepares for an interactive session. This is called after the user has 296 * been successfully authenticated. During this message exchange, pseudo 297 * terminals are allocated, X11, TCP/IP, and authentication agent forwardings 298 * are requested, etc. 299 */ 300 static void 301 do_authenticated1(Authctxt *authctxt) 302 { 303 Session *s; 304 char *command; 305 int success, type, screen_flag; 306 int enable_compression_after_reply = 0; 307 u_int proto_len, data_len, dlen, compression_level = 0; 308 309 s = session_new(); 310 if (s == NULL) { 311 error("no more sessions"); 312 return; 313 } 314 s->authctxt = authctxt; 315 s->pw = authctxt->pw; 316 317 /* 318 * We stay in this loop until the client requests to execute a shell 319 * or a command. 320 */ 321 for (;;) { 322 success = 0; 323 324 /* Get a packet from the client. */ 325 type = packet_read(); 326 327 /* Process the packet. */ 328 switch (type) { 329 case SSH_CMSG_REQUEST_COMPRESSION: 330 compression_level = packet_get_int(); 331 packet_check_eom(); 332 if (compression_level < 1 || compression_level > 9) { 333 packet_send_debug("Received invalid compression level %d.", 334 compression_level); 335 break; 336 } 337 if (options.compression == COMP_NONE) { 338 debug2("compression disabled"); 339 break; 340 } 341 /* Enable compression after we have responded with SUCCESS. */ 342 enable_compression_after_reply = 1; 343 success = 1; 344 break; 345 346 case SSH_CMSG_REQUEST_PTY: 347 success = session_pty_req(s); 348 break; 349 350 case SSH_CMSG_X11_REQUEST_FORWARDING: 351 s->auth_proto = packet_get_string(&proto_len); 352 s->auth_data = packet_get_string(&data_len); 353 354 screen_flag = packet_get_protocol_flags() & 355 SSH_PROTOFLAG_SCREEN_NUMBER; 356 debug2("SSH_PROTOFLAG_SCREEN_NUMBER: %d", screen_flag); 357 358 if (packet_remaining() == 4) { 359 if (!screen_flag) 360 debug2("Buggy client: " 361 "X11 screen flag missing"); 362 s->screen = packet_get_int(); 363 } else { 364 s->screen = 0; 365 } 366 packet_check_eom(); 367 if (xauth_valid_string(s->auth_proto) && 368 xauth_valid_string(s->auth_data)) 369 success = session_setup_x11fwd(s); 370 else { 371 success = 0; 372 error("Invalid X11 forwarding data"); 373 } 374 if (!success) { 375 free(s->auth_proto); 376 free(s->auth_data); 377 s->auth_proto = NULL; 378 s->auth_data = NULL; 379 } 380 break; 381 382 case SSH_CMSG_AGENT_REQUEST_FORWARDING: 383 if (!options.allow_agent_forwarding || 384 no_agent_forwarding_flag || compat13) { 385 debug("Authentication agent forwarding not permitted for this authentication."); 386 break; 387 } 388 debug("Received authentication agent forwarding request."); 389 success = auth_input_request_forwarding(s->pw); 390 break; 391 392 case SSH_CMSG_PORT_FORWARD_REQUEST: 393 if (no_port_forwarding_flag) { 394 debug("Port forwarding not permitted for this authentication."); 395 break; 396 } 397 if (!(options.allow_tcp_forwarding & FORWARD_REMOTE)) { 398 debug("Port forwarding not permitted."); 399 break; 400 } 401 debug("Received TCP/IP port forwarding request."); 402 if (channel_input_port_forward_request(s->pw->pw_uid == 0, 403 &options.fwd_opts) < 0) { 404 debug("Port forwarding failed."); 405 break; 406 } 407 success = 1; 408 break; 409 410 case SSH_CMSG_MAX_PACKET_SIZE: 411 if (packet_set_maxsize(packet_get_int()) > 0) 412 success = 1; 413 break; 414 415 case SSH_CMSG_EXEC_SHELL: 416 case SSH_CMSG_EXEC_CMD: 417 if (type == SSH_CMSG_EXEC_CMD) { 418 command = packet_get_string(&dlen); 419 debug("Exec command '%.500s'", command); 420 if (do_exec(s, command) != 0) 421 packet_disconnect( 422 "command execution failed"); 423 free(command); 424 } else { 425 if (do_exec(s, NULL) != 0) 426 packet_disconnect( 427 "shell execution failed"); 428 } 429 packet_check_eom(); 430 session_close(s); 431 return; 432 433 default: 434 /* 435 * Any unknown messages in this phase are ignored, 436 * and a failure message is returned. 437 */ 438 logit("Unknown packet type received after authentication: %d", type); 439 } 440 packet_start(success ? SSH_SMSG_SUCCESS : SSH_SMSG_FAILURE); 441 packet_send(); 442 packet_write_wait(); 443 444 /* Enable compression now that we have replied if appropriate. */ 445 if (enable_compression_after_reply) { 446 enable_compression_after_reply = 0; 447 packet_start_compression(compression_level); 448 } 449 } 450 } 451 452 #define USE_PIPES 1 453 /* 454 * This is called to fork and execute a command when we have no tty. This 455 * will call do_child from the child, and server_loop from the parent after 456 * setting up file descriptors and such. 457 */ 458 int 459 do_exec_no_pty(Session *s, const char *command) 460 { 461 pid_t pid; 462 463 #ifdef USE_PIPES 464 int pin[2], pout[2], perr[2]; 465 466 if (s == NULL) 467 fatal("do_exec_no_pty: no session"); 468 469 /* Allocate pipes for communicating with the program. */ 470 if (pipe(pin) < 0) { 471 error("%s: pipe in: %.100s", __func__, strerror(errno)); 472 return -1; 473 } 474 if (pipe(pout) < 0) { 475 error("%s: pipe out: %.100s", __func__, strerror(errno)); 476 close(pin[0]); 477 close(pin[1]); 478 return -1; 479 } 480 if (pipe(perr) < 0) { 481 error("%s: pipe err: %.100s", __func__, 482 strerror(errno)); 483 close(pin[0]); 484 close(pin[1]); 485 close(pout[0]); 486 close(pout[1]); 487 return -1; 488 } 489 #else 490 int inout[2], err[2]; 491 492 if (s == NULL) 493 fatal("do_exec_no_pty: no session"); 494 495 /* Uses socket pairs to communicate with the program. */ 496 if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) < 0) { 497 error("%s: socketpair #1: %.100s", __func__, strerror(errno)); 498 return -1; 499 } 500 if (socketpair(AF_UNIX, SOCK_STREAM, 0, err) < 0) { 501 error("%s: socketpair #2: %.100s", __func__, 502 strerror(errno)); 503 close(inout[0]); 504 close(inout[1]); 505 return -1; 506 } 507 #endif 508 509 session_proctitle(s); 510 511 /* Fork the child. */ 512 switch ((pid = fork())) { 513 case -1: 514 error("%s: fork: %.100s", __func__, strerror(errno)); 515 #ifdef USE_PIPES 516 close(pin[0]); 517 close(pin[1]); 518 close(pout[0]); 519 close(pout[1]); 520 close(perr[0]); 521 close(perr[1]); 522 #else 523 close(inout[0]); 524 close(inout[1]); 525 close(err[0]); 526 close(err[1]); 527 #endif 528 return -1; 529 case 0: 530 is_child = 1; 531 532 /* Child. Reinitialize the log since the pid has changed. */ 533 log_init(__progname, options.log_level, 534 options.log_facility, log_stderr); 535 536 /* 537 * Create a new session and process group since the 4.4BSD 538 * setlogin() affects the entire process group. 539 */ 540 if (setsid() < 0) 541 error("setsid failed: %.100s", strerror(errno)); 542 543 #ifdef USE_PIPES 544 /* 545 * Redirect stdin. We close the parent side of the socket 546 * pair, and make the child side the standard input. 547 */ 548 close(pin[1]); 549 if (dup2(pin[0], 0) < 0) 550 perror("dup2 stdin"); 551 close(pin[0]); 552 553 /* Redirect stdout. */ 554 close(pout[0]); 555 if (dup2(pout[1], 1) < 0) 556 perror("dup2 stdout"); 557 close(pout[1]); 558 559 /* Redirect stderr. */ 560 close(perr[0]); 561 if (dup2(perr[1], 2) < 0) 562 perror("dup2 stderr"); 563 close(perr[1]); 564 #else 565 /* 566 * Redirect stdin, stdout, and stderr. Stdin and stdout will 567 * use the same socket, as some programs (particularly rdist) 568 * seem to depend on it. 569 */ 570 close(inout[1]); 571 close(err[1]); 572 if (dup2(inout[0], 0) < 0) /* stdin */ 573 perror("dup2 stdin"); 574 if (dup2(inout[0], 1) < 0) /* stdout (same as stdin) */ 575 perror("dup2 stdout"); 576 close(inout[0]); 577 if (dup2(err[0], 2) < 0) /* stderr */ 578 perror("dup2 stderr"); 579 close(err[0]); 580 #endif 581 582 583 #ifdef _UNICOS 584 cray_init_job(s->pw); /* set up cray jid and tmpdir */ 585 #endif 586 587 /* Do processing for the child (exec command etc). */ 588 do_child(s, command); 589 /* NOTREACHED */ 590 default: 591 break; 592 } 593 594 #ifdef _UNICOS 595 signal(WJSIGNAL, cray_job_termination_handler); 596 #endif /* _UNICOS */ 597 #ifdef HAVE_CYGWIN 598 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); 599 #endif 600 601 s->pid = pid; 602 /* Set interactive/non-interactive mode. */ 603 packet_set_interactive(s->display != NULL, 604 options.ip_qos_interactive, options.ip_qos_bulk); 605 606 /* 607 * Clear loginmsg, since it's the child's responsibility to display 608 * it to the user, otherwise multiple sessions may accumulate 609 * multiple copies of the login messages. 610 */ 611 buffer_clear(&loginmsg); 612 613 #ifdef USE_PIPES 614 /* We are the parent. Close the child sides of the pipes. */ 615 close(pin[0]); 616 close(pout[1]); 617 close(perr[1]); 618 619 if (compat20) { 620 session_set_fds(s, pin[1], pout[0], perr[0], 621 s->is_subsystem, 0); 622 } else { 623 /* Enter the interactive session. */ 624 server_loop(pid, pin[1], pout[0], perr[0]); 625 /* server_loop has closed pin[1], pout[0], and perr[0]. */ 626 } 627 #else 628 /* We are the parent. Close the child sides of the socket pairs. */ 629 close(inout[0]); 630 close(err[0]); 631 632 /* 633 * Enter the interactive session. Note: server_loop must be able to 634 * handle the case that fdin and fdout are the same. 635 */ 636 if (compat20) { 637 session_set_fds(s, inout[1], inout[1], err[1], 638 s->is_subsystem, 0); 639 } else { 640 server_loop(pid, inout[1], inout[1], err[1]); 641 /* server_loop has closed inout[1] and err[1]. */ 642 } 643 #endif 644 return 0; 645 } 646 647 /* 648 * This is called to fork and execute a command when we have a tty. This 649 * will call do_child from the child, and server_loop from the parent after 650 * setting up file descriptors, controlling tty, updating wtmp, utmp, 651 * lastlog, and other such operations. 652 */ 653 int 654 do_exec_pty(Session *s, const char *command) 655 { 656 int fdout, ptyfd, ttyfd, ptymaster; 657 pid_t pid; 658 659 if (s == NULL) 660 fatal("do_exec_pty: no session"); 661 ptyfd = s->ptyfd; 662 ttyfd = s->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 * Do this before forking (and cleanup in the child) so as to 669 * detect and gracefully fail out-of-fd conditions. 670 */ 671 if ((fdout = dup(ptyfd)) < 0) { 672 error("%s: dup #1: %s", __func__, strerror(errno)); 673 close(ttyfd); 674 close(ptyfd); 675 return -1; 676 } 677 /* we keep a reference to the pty master */ 678 if ((ptymaster = dup(ptyfd)) < 0) { 679 error("%s: dup #2: %s", __func__, strerror(errno)); 680 close(ttyfd); 681 close(ptyfd); 682 close(fdout); 683 return -1; 684 } 685 686 /* Fork the child. */ 687 switch ((pid = fork())) { 688 case -1: 689 error("%s: fork: %.100s", __func__, strerror(errno)); 690 close(fdout); 691 close(ptymaster); 692 close(ttyfd); 693 close(ptyfd); 694 return -1; 695 case 0: 696 is_child = 1; 697 698 close(fdout); 699 close(ptymaster); 700 701 /* Child. Reinitialize the log because the pid has changed. */ 702 log_init(__progname, options.log_level, 703 options.log_facility, log_stderr); 704 /* Close the master side of the pseudo tty. */ 705 close(ptyfd); 706 707 /* Make the pseudo tty our controlling tty. */ 708 pty_make_controlling_tty(&ttyfd, s->tty); 709 710 /* Redirect stdin/stdout/stderr from the pseudo tty. */ 711 if (dup2(ttyfd, 0) < 0) 712 error("dup2 stdin: %s", strerror(errno)); 713 if (dup2(ttyfd, 1) < 0) 714 error("dup2 stdout: %s", strerror(errno)); 715 if (dup2(ttyfd, 2) < 0) 716 error("dup2 stderr: %s", strerror(errno)); 717 718 /* Close the extra descriptor for the pseudo tty. */ 719 close(ttyfd); 720 721 /* record login, etc. similar to login(1) */ 722 #ifndef HAVE_OSF_SIA 723 if (!(options.use_login && command == NULL)) { 724 #ifdef _UNICOS 725 cray_init_job(s->pw); /* set up cray jid and tmpdir */ 726 #endif /* _UNICOS */ 727 do_login(s, command); 728 } 729 # ifdef LOGIN_NEEDS_UTMPX 730 else 731 do_pre_login(s); 732 # endif 733 #endif 734 /* 735 * Do common processing for the child, such as execing 736 * the command. 737 */ 738 do_child(s, command); 739 /* NOTREACHED */ 740 default: 741 break; 742 } 743 744 #ifdef _UNICOS 745 signal(WJSIGNAL, cray_job_termination_handler); 746 #endif /* _UNICOS */ 747 #ifdef HAVE_CYGWIN 748 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); 749 #endif 750 751 s->pid = pid; 752 753 /* Parent. Close the slave side of the pseudo tty. */ 754 close(ttyfd); 755 756 /* Enter interactive session. */ 757 s->ptymaster = ptymaster; 758 packet_set_interactive(1, 759 options.ip_qos_interactive, options.ip_qos_bulk); 760 if (compat20) { 761 session_set_fds(s, ptyfd, fdout, -1, 1, 1); 762 } else { 763 server_loop(pid, ptyfd, fdout, -1); 764 /* server_loop _has_ closed ptyfd and fdout. */ 765 } 766 return 0; 767 } 768 769 #ifdef LOGIN_NEEDS_UTMPX 770 static void 771 do_pre_login(Session *s) 772 { 773 socklen_t fromlen; 774 struct sockaddr_storage from; 775 pid_t pid = getpid(); 776 777 /* 778 * Get IP address of client. If the connection is not a socket, let 779 * the address be 0.0.0.0. 780 */ 781 memset(&from, 0, sizeof(from)); 782 fromlen = sizeof(from); 783 if (packet_connection_is_on_socket()) { 784 if (getpeername(packet_get_connection_in(), 785 (struct sockaddr *)&from, &fromlen) < 0) { 786 debug("getpeername: %.100s", strerror(errno)); 787 cleanup_exit(255); 788 } 789 } 790 791 record_utmp_only(pid, s->tty, s->pw->pw_name, 792 get_remote_name_or_ip(utmp_len, options.use_dns), 793 (struct sockaddr *)&from, fromlen); 794 } 795 #endif 796 797 /* 798 * This is called to fork and execute a command. If another command is 799 * to be forced, execute that instead. 800 */ 801 int 802 do_exec(Session *s, const char *command) 803 { 804 int ret; 805 const char *forced = NULL, *tty = NULL; 806 char session_type[1024]; 807 808 if (options.adm_forced_command) { 809 original_command = command; 810 command = options.adm_forced_command; 811 forced = "(config)"; 812 } else if (forced_command) { 813 original_command = command; 814 command = forced_command; 815 forced = "(key-option)"; 816 } 817 if (forced != NULL) { 818 if (IS_INTERNAL_SFTP(command)) { 819 s->is_subsystem = s->is_subsystem ? 820 SUBSYSTEM_INT_SFTP : SUBSYSTEM_INT_SFTP_ERROR; 821 } else if (s->is_subsystem) 822 s->is_subsystem = SUBSYSTEM_EXT; 823 snprintf(session_type, sizeof(session_type), 824 "forced-command %s '%.900s'", forced, command); 825 } else if (s->is_subsystem) { 826 snprintf(session_type, sizeof(session_type), 827 "subsystem '%.900s'", s->subsys); 828 } else if (command == NULL) { 829 snprintf(session_type, sizeof(session_type), "shell"); 830 } else { 831 /* NB. we don't log unforced commands to preserve privacy */ 832 snprintf(session_type, sizeof(session_type), "command"); 833 } 834 835 if (s->ttyfd != -1) { 836 tty = s->tty; 837 if (strncmp(tty, "/dev/", 5) == 0) 838 tty += 5; 839 } 840 841 verbose("Starting session: %s%s%s for %s from %.200s port %d id %d", 842 session_type, 843 tty == NULL ? "" : " on ", 844 tty == NULL ? "" : tty, 845 s->pw->pw_name, 846 get_remote_ipaddr(), 847 get_remote_port(), 848 s->self); 849 850 #ifdef SSH_AUDIT_EVENTS 851 if (command != NULL) 852 PRIVSEP(audit_run_command(command)); 853 else if (s->ttyfd == -1) { 854 char *shell = s->pw->pw_shell; 855 856 if (shell[0] == '\0') /* empty shell means /bin/sh */ 857 shell =_PATH_BSHELL; 858 PRIVSEP(audit_run_command(shell)); 859 } 860 #endif 861 if (s->ttyfd != -1) 862 ret = do_exec_pty(s, command); 863 else 864 ret = do_exec_no_pty(s, command); 865 866 original_command = NULL; 867 868 /* 869 * Clear loginmsg: it's the child's responsibility to display 870 * it to the user, otherwise multiple sessions may accumulate 871 * multiple copies of the login messages. 872 */ 873 buffer_clear(&loginmsg); 874 875 return ret; 876 } 877 878 /* administrative, login(1)-like work */ 879 void 880 do_login(Session *s, const char *command) 881 { 882 socklen_t fromlen; 883 struct sockaddr_storage from; 884 struct passwd * pw = s->pw; 885 pid_t pid = getpid(); 886 887 /* 888 * Get IP address of client. If the connection is not a socket, let 889 * the address be 0.0.0.0. 890 */ 891 memset(&from, 0, sizeof(from)); 892 fromlen = sizeof(from); 893 if (packet_connection_is_on_socket()) { 894 if (getpeername(packet_get_connection_in(), 895 (struct sockaddr *)&from, &fromlen) < 0) { 896 debug("getpeername: %.100s", strerror(errno)); 897 cleanup_exit(255); 898 } 899 } 900 901 /* Record that there was a login on that tty from the remote host. */ 902 if (!use_privsep) 903 record_login(pid, s->tty, pw->pw_name, pw->pw_uid, 904 get_remote_name_or_ip(utmp_len, 905 options.use_dns), 906 (struct sockaddr *)&from, fromlen); 907 908 #ifdef USE_PAM 909 /* 910 * If password change is needed, do it now. 911 * This needs to occur before the ~/.hushlogin check. 912 */ 913 if (options.use_pam && !use_privsep && s->authctxt->force_pwchange) { 914 display_loginmsg(); 915 do_pam_chauthtok(); 916 s->authctxt->force_pwchange = 0; 917 /* XXX - signal [net] parent to enable forwardings */ 918 } 919 #endif 920 921 if (check_quietlogin(s, command)) 922 return; 923 924 display_loginmsg(); 925 926 do_motd(); 927 } 928 929 /* 930 * Display the message of the day. 931 */ 932 void 933 do_motd(void) 934 { 935 FILE *f; 936 char buf[256]; 937 938 if (options.print_motd) { 939 #ifdef HAVE_LOGIN_CAP 940 f = fopen(login_getcapstr(lc, "welcome", "/etc/motd", 941 "/etc/motd"), "r"); 942 #else 943 f = fopen("/etc/motd", "r"); 944 #endif 945 if (f) { 946 while (fgets(buf, sizeof(buf), f)) 947 fputs(buf, stdout); 948 fclose(f); 949 } 950 } 951 } 952 953 954 /* 955 * Check for quiet login, either .hushlogin or command given. 956 */ 957 int 958 check_quietlogin(Session *s, const char *command) 959 { 960 char buf[256]; 961 struct passwd *pw = s->pw; 962 struct stat st; 963 964 /* Return 1 if .hushlogin exists or a command given. */ 965 if (command != NULL) 966 return 1; 967 snprintf(buf, sizeof(buf), "%.200s/.hushlogin", pw->pw_dir); 968 #ifdef HAVE_LOGIN_CAP 969 if (login_getcapbool(lc, "hushlogin", 0) || stat(buf, &st) >= 0) 970 return 1; 971 #else 972 if (stat(buf, &st) >= 0) 973 return 1; 974 #endif 975 return 0; 976 } 977 978 /* 979 * Sets the value of the given variable in the environment. If the variable 980 * already exists, its value is overridden. 981 */ 982 void 983 child_set_env(char ***envp, u_int *envsizep, const char *name, 984 const char *value) 985 { 986 char **env; 987 u_int envsize; 988 u_int i, namelen; 989 990 if (strchr(name, '=') != NULL) { 991 error("Invalid environment variable \"%.100s\"", name); 992 return; 993 } 994 995 /* 996 * If we're passed an uninitialized list, allocate a single null 997 * entry before continuing. 998 */ 999 if (*envp == NULL && *envsizep == 0) { 1000 *envp = xmalloc(sizeof(char *)); 1001 *envp[0] = NULL; 1002 *envsizep = 1; 1003 } 1004 1005 /* 1006 * Find the slot where the value should be stored. If the variable 1007 * already exists, we reuse the slot; otherwise we append a new slot 1008 * at the end of the array, expanding if necessary. 1009 */ 1010 env = *envp; 1011 namelen = strlen(name); 1012 for (i = 0; env[i]; i++) 1013 if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=') 1014 break; 1015 if (env[i]) { 1016 /* Reuse the slot. */ 1017 free(env[i]); 1018 } else { 1019 /* New variable. Expand if necessary. */ 1020 envsize = *envsizep; 1021 if (i >= envsize - 1) { 1022 if (envsize >= 1000) 1023 fatal("child_set_env: too many env vars"); 1024 envsize += 50; 1025 env = (*envp) = xreallocarray(env, envsize, sizeof(char *)); 1026 *envsizep = envsize; 1027 } 1028 /* Need to set the NULL pointer at end of array beyond the new slot. */ 1029 env[i + 1] = NULL; 1030 } 1031 1032 /* Allocate space and format the variable in the appropriate slot. */ 1033 env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1); 1034 snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value); 1035 } 1036 1037 /* 1038 * Reads environment variables from the given file and adds/overrides them 1039 * into the environment. If the file does not exist, this does nothing. 1040 * Otherwise, it must consist of empty lines, comments (line starts with '#') 1041 * and assignments of the form name=value. No other forms are allowed. 1042 */ 1043 static void 1044 read_environment_file(char ***env, u_int *envsize, 1045 const char *filename) 1046 { 1047 FILE *f; 1048 char buf[4096]; 1049 char *cp, *value; 1050 u_int lineno = 0; 1051 1052 f = fopen(filename, "r"); 1053 if (!f) 1054 return; 1055 1056 while (fgets(buf, sizeof(buf), f)) { 1057 if (++lineno > 1000) 1058 fatal("Too many lines in environment file %s", filename); 1059 for (cp = buf; *cp == ' ' || *cp == '\t'; cp++) 1060 ; 1061 if (!*cp || *cp == '#' || *cp == '\n') 1062 continue; 1063 1064 cp[strcspn(cp, "\n")] = '\0'; 1065 1066 value = strchr(cp, '='); 1067 if (value == NULL) { 1068 fprintf(stderr, "Bad line %u in %.100s\n", lineno, 1069 filename); 1070 continue; 1071 } 1072 /* 1073 * Replace the equals sign by nul, and advance value to 1074 * the value string. 1075 */ 1076 *value = '\0'; 1077 value++; 1078 child_set_env(env, envsize, cp, value); 1079 } 1080 fclose(f); 1081 } 1082 1083 #ifdef HAVE_ETC_DEFAULT_LOGIN 1084 /* 1085 * Return named variable from specified environment, or NULL if not present. 1086 */ 1087 static char * 1088 child_get_env(char **env, const char *name) 1089 { 1090 int i; 1091 size_t len; 1092 1093 len = strlen(name); 1094 for (i=0; env[i] != NULL; i++) 1095 if (strncmp(name, env[i], len) == 0 && env[i][len] == '=') 1096 return(env[i] + len + 1); 1097 return NULL; 1098 } 1099 1100 /* 1101 * Read /etc/default/login. 1102 * We pick up the PATH (or SUPATH for root) and UMASK. 1103 */ 1104 static void 1105 read_etc_default_login(char ***env, u_int *envsize, uid_t uid) 1106 { 1107 char **tmpenv = NULL, *var; 1108 u_int i, tmpenvsize = 0; 1109 u_long mask; 1110 1111 /* 1112 * We don't want to copy the whole file to the child's environment, 1113 * so we use a temporary environment and copy the variables we're 1114 * interested in. 1115 */ 1116 read_environment_file(&tmpenv, &tmpenvsize, "/etc/default/login"); 1117 1118 if (tmpenv == NULL) 1119 return; 1120 1121 if (uid == 0) 1122 var = child_get_env(tmpenv, "SUPATH"); 1123 else 1124 var = child_get_env(tmpenv, "PATH"); 1125 if (var != NULL) 1126 child_set_env(env, envsize, "PATH", var); 1127 1128 if ((var = child_get_env(tmpenv, "UMASK")) != NULL) 1129 if (sscanf(var, "%5lo", &mask) == 1) 1130 umask((mode_t)mask); 1131 1132 for (i = 0; tmpenv[i] != NULL; i++) 1133 free(tmpenv[i]); 1134 free(tmpenv); 1135 } 1136 #endif /* HAVE_ETC_DEFAULT_LOGIN */ 1137 1138 void 1139 copy_environment(char **source, char ***env, u_int *envsize) 1140 { 1141 char *var_name, *var_val; 1142 int i; 1143 1144 if (source == NULL) 1145 return; 1146 1147 for(i = 0; source[i] != NULL; i++) { 1148 var_name = xstrdup(source[i]); 1149 if ((var_val = strstr(var_name, "=")) == NULL) { 1150 free(var_name); 1151 continue; 1152 } 1153 *var_val++ = '\0'; 1154 1155 debug3("Copy environment: %s=%s", var_name, var_val); 1156 child_set_env(env, envsize, var_name, var_val); 1157 1158 free(var_name); 1159 } 1160 } 1161 1162 static char ** 1163 do_setup_env(Session *s, const char *shell) 1164 { 1165 char buf[256]; 1166 u_int i, envsize; 1167 char **env, *laddr; 1168 struct passwd *pw = s->pw; 1169 #if !defined (HAVE_LOGIN_CAP) && !defined (HAVE_CYGWIN) 1170 char *path = NULL; 1171 #else 1172 extern char **environ; 1173 char **senv, **var; 1174 #endif 1175 1176 /* Initialize the environment. */ 1177 envsize = 100; 1178 env = xcalloc(envsize, sizeof(char *)); 1179 env[0] = NULL; 1180 1181 #ifdef HAVE_CYGWIN 1182 /* 1183 * The Windows environment contains some setting which are 1184 * important for a running system. They must not be dropped. 1185 */ 1186 { 1187 char **p; 1188 1189 p = fetch_windows_environment(); 1190 copy_environment(p, &env, &envsize); 1191 free_windows_environment(p); 1192 } 1193 #endif 1194 1195 if (getenv("TZ")) 1196 child_set_env(&env, &envsize, "TZ", getenv("TZ")); 1197 1198 #ifdef GSSAPI 1199 /* Allow any GSSAPI methods that we've used to alter 1200 * the childs environment as they see fit 1201 */ 1202 ssh_gssapi_do_child(&env, &envsize); 1203 #endif 1204 1205 if (!options.use_login) { 1206 /* Set basic environment. */ 1207 for (i = 0; i < s->num_env; i++) 1208 child_set_env(&env, &envsize, s->env[i].name, 1209 s->env[i].val); 1210 1211 child_set_env(&env, &envsize, "USER", pw->pw_name); 1212 child_set_env(&env, &envsize, "LOGNAME", pw->pw_name); 1213 #ifdef _AIX 1214 child_set_env(&env, &envsize, "LOGIN", pw->pw_name); 1215 #endif 1216 child_set_env(&env, &envsize, "HOME", pw->pw_dir); 1217 snprintf(buf, sizeof buf, "%.200s/%.50s", 1218 _PATH_MAILDIR, pw->pw_name); 1219 child_set_env(&env, &envsize, "MAIL", buf); 1220 #ifdef HAVE_LOGIN_CAP 1221 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); 1222 child_set_env(&env, &envsize, "TERM", "su"); 1223 senv = environ; 1224 environ = xmalloc(sizeof(char *)); 1225 *environ = NULL; 1226 (void) setusercontext(lc, pw, pw->pw_uid, 1227 LOGIN_SETENV|LOGIN_SETPATH); 1228 copy_environment(environ, &env, &envsize); 1229 for (var = environ; *var != NULL; ++var) 1230 free(*var); 1231 free(environ); 1232 environ = senv; 1233 #else /* HAVE_LOGIN_CAP */ 1234 # ifndef HAVE_CYGWIN 1235 /* 1236 * There's no standard path on Windows. The path contains 1237 * important components pointing to the system directories, 1238 * needed for loading shared libraries. So the path better 1239 * remains intact here. 1240 */ 1241 # ifdef HAVE_ETC_DEFAULT_LOGIN 1242 read_etc_default_login(&env, &envsize, pw->pw_uid); 1243 path = child_get_env(env, "PATH"); 1244 # endif /* HAVE_ETC_DEFAULT_LOGIN */ 1245 if (path == NULL || *path == '\0') { 1246 child_set_env(&env, &envsize, "PATH", 1247 s->pw->pw_uid == 0 ? 1248 SUPERUSER_PATH : _PATH_STDPATH); 1249 } 1250 # endif /* HAVE_CYGWIN */ 1251 #endif /* HAVE_LOGIN_CAP */ 1252 1253 /* Normal systems set SHELL by default. */ 1254 child_set_env(&env, &envsize, "SHELL", shell); 1255 } 1256 1257 /* Set custom environment options from RSA authentication. */ 1258 if (!options.use_login) { 1259 while (custom_environment) { 1260 struct envstring *ce = custom_environment; 1261 char *str = ce->s; 1262 1263 for (i = 0; str[i] != '=' && str[i]; i++) 1264 ; 1265 if (str[i] == '=') { 1266 str[i] = 0; 1267 child_set_env(&env, &envsize, str, str + i + 1); 1268 } 1269 custom_environment = ce->next; 1270 free(ce->s); 1271 free(ce); 1272 } 1273 } 1274 1275 /* SSH_CLIENT deprecated */ 1276 snprintf(buf, sizeof buf, "%.50s %d %d", 1277 get_remote_ipaddr(), get_remote_port(), get_local_port()); 1278 child_set_env(&env, &envsize, "SSH_CLIENT", buf); 1279 1280 laddr = get_local_ipaddr(packet_get_connection_in()); 1281 snprintf(buf, sizeof buf, "%.50s %d %.50s %d", 1282 get_remote_ipaddr(), get_remote_port(), laddr, get_local_port()); 1283 free(laddr); 1284 child_set_env(&env, &envsize, "SSH_CONNECTION", buf); 1285 1286 if (s->ttyfd != -1) 1287 child_set_env(&env, &envsize, "SSH_TTY", s->tty); 1288 if (s->term) 1289 child_set_env(&env, &envsize, "TERM", s->term); 1290 if (s->display) 1291 child_set_env(&env, &envsize, "DISPLAY", s->display); 1292 if (original_command) 1293 child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND", 1294 original_command); 1295 1296 #ifdef _UNICOS 1297 if (cray_tmpdir[0] != '\0') 1298 child_set_env(&env, &envsize, "TMPDIR", cray_tmpdir); 1299 #endif /* _UNICOS */ 1300 1301 /* 1302 * Since we clear KRB5CCNAME at startup, if it's set now then it 1303 * must have been set by a native authentication method (eg AIX or 1304 * SIA), so copy it to the child. 1305 */ 1306 { 1307 char *cp; 1308 1309 if ((cp = getenv("KRB5CCNAME")) != NULL) 1310 child_set_env(&env, &envsize, "KRB5CCNAME", cp); 1311 } 1312 1313 #ifdef _AIX 1314 { 1315 char *cp; 1316 1317 if ((cp = getenv("AUTHSTATE")) != NULL) 1318 child_set_env(&env, &envsize, "AUTHSTATE", cp); 1319 read_environment_file(&env, &envsize, "/etc/environment"); 1320 } 1321 #endif 1322 #ifdef KRB5 1323 if (s->authctxt->krb5_ccname) 1324 child_set_env(&env, &envsize, "KRB5CCNAME", 1325 s->authctxt->krb5_ccname); 1326 #endif 1327 #ifdef USE_PAM 1328 /* 1329 * Pull in any environment variables that may have 1330 * been set by PAM. 1331 */ 1332 if (options.use_pam) { 1333 char **p; 1334 1335 p = fetch_pam_child_environment(); 1336 copy_environment(p, &env, &envsize); 1337 free_pam_environment(p); 1338 1339 p = fetch_pam_environment(); 1340 copy_environment(p, &env, &envsize); 1341 free_pam_environment(p); 1342 } 1343 #endif /* USE_PAM */ 1344 1345 if (auth_sock_name != NULL) 1346 child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME, 1347 auth_sock_name); 1348 1349 /* read $HOME/.ssh/environment. */ 1350 if (options.permit_user_env && !options.use_login) { 1351 snprintf(buf, sizeof buf, "%.200s/.ssh/environment", 1352 strcmp(pw->pw_dir, "/") ? pw->pw_dir : ""); 1353 read_environment_file(&env, &envsize, buf); 1354 } 1355 if (debug_flag) { 1356 /* dump the environment */ 1357 fprintf(stderr, "Environment:\n"); 1358 for (i = 0; env[i]; i++) 1359 fprintf(stderr, " %.200s\n", env[i]); 1360 } 1361 return env; 1362 } 1363 1364 /* 1365 * Run $HOME/.ssh/rc, /etc/ssh/sshrc, or xauth (whichever is found 1366 * first in this order). 1367 */ 1368 static void 1369 do_rc_files(Session *s, const char *shell) 1370 { 1371 FILE *f = NULL; 1372 char cmd[1024]; 1373 int do_xauth; 1374 struct stat st; 1375 1376 do_xauth = 1377 s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL; 1378 1379 /* ignore _PATH_SSH_USER_RC for subsystems and admin forced commands */ 1380 if (!s->is_subsystem && options.adm_forced_command == NULL && 1381 !no_user_rc && options.permit_user_rc && 1382 stat(_PATH_SSH_USER_RC, &st) >= 0) { 1383 snprintf(cmd, sizeof cmd, "%s -c '%s %s'", 1384 shell, _PATH_BSHELL, _PATH_SSH_USER_RC); 1385 if (debug_flag) 1386 fprintf(stderr, "Running %s\n", cmd); 1387 f = popen(cmd, "w"); 1388 if (f) { 1389 if (do_xauth) 1390 fprintf(f, "%s %s\n", s->auth_proto, 1391 s->auth_data); 1392 pclose(f); 1393 } else 1394 fprintf(stderr, "Could not run %s\n", 1395 _PATH_SSH_USER_RC); 1396 } else if (stat(_PATH_SSH_SYSTEM_RC, &st) >= 0) { 1397 if (debug_flag) 1398 fprintf(stderr, "Running %s %s\n", _PATH_BSHELL, 1399 _PATH_SSH_SYSTEM_RC); 1400 f = popen(_PATH_BSHELL " " _PATH_SSH_SYSTEM_RC, "w"); 1401 if (f) { 1402 if (do_xauth) 1403 fprintf(f, "%s %s\n", s->auth_proto, 1404 s->auth_data); 1405 pclose(f); 1406 } else 1407 fprintf(stderr, "Could not run %s\n", 1408 _PATH_SSH_SYSTEM_RC); 1409 } else if (do_xauth && options.xauth_location != NULL) { 1410 /* Add authority data to .Xauthority if appropriate. */ 1411 if (debug_flag) { 1412 fprintf(stderr, 1413 "Running %.500s remove %.100s\n", 1414 options.xauth_location, s->auth_display); 1415 fprintf(stderr, 1416 "%.500s add %.100s %.100s %.100s\n", 1417 options.xauth_location, s->auth_display, 1418 s->auth_proto, s->auth_data); 1419 } 1420 snprintf(cmd, sizeof cmd, "%s -q -", 1421 options.xauth_location); 1422 f = popen(cmd, "w"); 1423 if (f) { 1424 fprintf(f, "remove %s\n", 1425 s->auth_display); 1426 fprintf(f, "add %s %s %s\n", 1427 s->auth_display, s->auth_proto, 1428 s->auth_data); 1429 pclose(f); 1430 } else { 1431 fprintf(stderr, "Could not run %s\n", 1432 cmd); 1433 } 1434 } 1435 } 1436 1437 static void 1438 do_nologin(struct passwd *pw) 1439 { 1440 FILE *f = NULL; 1441 char buf[1024], *nl, *def_nl = _PATH_NOLOGIN; 1442 struct stat sb; 1443 1444 #ifdef HAVE_LOGIN_CAP 1445 if (login_getcapbool(lc, "ignorenologin", 0) || pw->pw_uid == 0) 1446 return; 1447 nl = login_getcapstr(lc, "nologin", def_nl, def_nl); 1448 #else 1449 if (pw->pw_uid == 0) 1450 return; 1451 nl = def_nl; 1452 #endif 1453 if (stat(nl, &sb) == -1) { 1454 if (nl != def_nl) 1455 free(nl); 1456 return; 1457 } 1458 1459 /* /etc/nologin exists. Print its contents if we can and exit. */ 1460 logit("User %.100s not allowed because %s exists", pw->pw_name, nl); 1461 if ((f = fopen(nl, "r")) != NULL) { 1462 while (fgets(buf, sizeof(buf), f)) 1463 fputs(buf, stderr); 1464 fclose(f); 1465 } 1466 exit(254); 1467 } 1468 1469 /* 1470 * Chroot into a directory after checking it for safety: all path components 1471 * must be root-owned directories with strict permissions. 1472 */ 1473 static void 1474 safely_chroot(const char *path, uid_t uid) 1475 { 1476 const char *cp; 1477 char component[PATH_MAX]; 1478 struct stat st; 1479 1480 if (*path != '/') 1481 fatal("chroot path does not begin at root"); 1482 if (strlen(path) >= sizeof(component)) 1483 fatal("chroot path too long"); 1484 1485 /* 1486 * Descend the path, checking that each component is a 1487 * root-owned directory with strict permissions. 1488 */ 1489 for (cp = path; cp != NULL;) { 1490 if ((cp = strchr(cp, '/')) == NULL) 1491 strlcpy(component, path, sizeof(component)); 1492 else { 1493 cp++; 1494 memcpy(component, path, cp - path); 1495 component[cp - path] = '\0'; 1496 } 1497 1498 debug3("%s: checking '%s'", __func__, component); 1499 1500 if (stat(component, &st) != 0) 1501 fatal("%s: stat(\"%s\"): %s", __func__, 1502 component, strerror(errno)); 1503 if (st.st_uid != 0 || (st.st_mode & 022) != 0) 1504 fatal("bad ownership or modes for chroot " 1505 "directory %s\"%s\"", 1506 cp == NULL ? "" : "component ", component); 1507 if (!S_ISDIR(st.st_mode)) 1508 fatal("chroot path %s\"%s\" is not a directory", 1509 cp == NULL ? "" : "component ", component); 1510 1511 } 1512 1513 if (chdir(path) == -1) 1514 fatal("Unable to chdir to chroot path \"%s\": " 1515 "%s", path, strerror(errno)); 1516 if (chroot(path) == -1) 1517 fatal("chroot(\"%s\"): %s", path, strerror(errno)); 1518 if (chdir("/") == -1) 1519 fatal("%s: chdir(/) after chroot: %s", 1520 __func__, strerror(errno)); 1521 verbose("Changed root directory to \"%s\"", path); 1522 } 1523 1524 /* Set login name, uid, gid, and groups. */ 1525 void 1526 do_setusercontext(struct passwd *pw) 1527 { 1528 char *chroot_path, *tmp; 1529 1530 platform_setusercontext(pw); 1531 1532 if (platform_privileged_uidswap()) { 1533 #ifdef HAVE_LOGIN_CAP 1534 if (setusercontext(lc, pw, pw->pw_uid, 1535 (LOGIN_SETALL & ~(LOGIN_SETENV|LOGIN_SETPATH|LOGIN_SETUSER))) < 0) { 1536 perror("unable to set user context"); 1537 exit(1); 1538 } 1539 #else 1540 if (setlogin(pw->pw_name) < 0) 1541 error("setlogin failed: %s", strerror(errno)); 1542 if (setgid(pw->pw_gid) < 0) { 1543 perror("setgid"); 1544 exit(1); 1545 } 1546 /* Initialize the group list. */ 1547 if (initgroups(pw->pw_name, pw->pw_gid) < 0) { 1548 perror("initgroups"); 1549 exit(1); 1550 } 1551 endgrent(); 1552 #endif 1553 1554 platform_setusercontext_post_groups(pw); 1555 1556 if (!in_chroot && options.chroot_directory != NULL && 1557 strcasecmp(options.chroot_directory, "none") != 0) { 1558 tmp = tilde_expand_filename(options.chroot_directory, 1559 pw->pw_uid); 1560 chroot_path = percent_expand(tmp, "h", pw->pw_dir, 1561 "u", pw->pw_name, (char *)NULL); 1562 safely_chroot(chroot_path, pw->pw_uid); 1563 free(tmp); 1564 free(chroot_path); 1565 /* Make sure we don't attempt to chroot again */ 1566 free(options.chroot_directory); 1567 options.chroot_directory = NULL; 1568 in_chroot = 1; 1569 } 1570 1571 #ifdef HAVE_LOGIN_CAP 1572 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUSER) < 0) { 1573 perror("unable to set user context (setuser)"); 1574 exit(1); 1575 } 1576 /* 1577 * FreeBSD's setusercontext() will not apply the user's 1578 * own umask setting unless running with the user's UID. 1579 */ 1580 (void) setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUMASK); 1581 #else 1582 # ifdef USE_LIBIAF 1583 /* 1584 * In a chroot environment, the set_id() will always fail; 1585 * typically because of the lack of necessary authentication 1586 * services and runtime such as ./usr/lib/libiaf.so, 1587 * ./usr/lib/libpam.so.1, and ./etc/passwd We skip it in the 1588 * internal sftp chroot case. We'll lose auditing and ACLs but 1589 * permanently_set_uid will take care of the rest. 1590 */ 1591 if (!in_chroot && set_id(pw->pw_name) != 0) 1592 fatal("set_id(%s) Failed", pw->pw_name); 1593 # endif /* USE_LIBIAF */ 1594 /* Permanently switch to the desired uid. */ 1595 permanently_set_uid(pw); 1596 #endif 1597 } else if (options.chroot_directory != NULL && 1598 strcasecmp(options.chroot_directory, "none") != 0) { 1599 fatal("server lacks privileges to chroot to ChrootDirectory"); 1600 } 1601 1602 if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) 1603 fatal("Failed to set uids to %u.", (u_int) pw->pw_uid); 1604 } 1605 1606 static void 1607 do_pwchange(Session *s) 1608 { 1609 fflush(NULL); 1610 fprintf(stderr, "WARNING: Your password has expired.\n"); 1611 if (s->ttyfd != -1) { 1612 fprintf(stderr, 1613 "You must change your password now and login again!\n"); 1614 #ifdef WITH_SELINUX 1615 setexeccon(NULL); 1616 #endif 1617 #ifdef PASSWD_NEEDS_USERNAME 1618 execl(_PATH_PASSWD_PROG, "passwd", s->pw->pw_name, 1619 (char *)NULL); 1620 #else 1621 execl(_PATH_PASSWD_PROG, "passwd", (char *)NULL); 1622 #endif 1623 perror("passwd"); 1624 } else { 1625 fprintf(stderr, 1626 "Password change required but no TTY available.\n"); 1627 } 1628 exit(1); 1629 } 1630 1631 static void 1632 launch_login(struct passwd *pw, const char *hostname) 1633 { 1634 /* Launch login(1). */ 1635 1636 execl(LOGIN_PROGRAM, "login", "-h", hostname, 1637 #ifdef xxxLOGIN_NEEDS_TERM 1638 (s->term ? s->term : "unknown"), 1639 #endif /* LOGIN_NEEDS_TERM */ 1640 #ifdef LOGIN_NO_ENDOPT 1641 "-p", "-f", pw->pw_name, (char *)NULL); 1642 #else 1643 "-p", "-f", "--", pw->pw_name, (char *)NULL); 1644 #endif 1645 1646 /* Login couldn't be executed, die. */ 1647 1648 perror("login"); 1649 exit(1); 1650 } 1651 1652 static void 1653 child_close_fds(void) 1654 { 1655 extern int auth_sock; 1656 1657 if (auth_sock != -1) { 1658 close(auth_sock); 1659 auth_sock = -1; 1660 } 1661 1662 if (packet_get_connection_in() == packet_get_connection_out()) 1663 close(packet_get_connection_in()); 1664 else { 1665 close(packet_get_connection_in()); 1666 close(packet_get_connection_out()); 1667 } 1668 /* 1669 * Close all descriptors related to channels. They will still remain 1670 * open in the parent. 1671 */ 1672 /* XXX better use close-on-exec? -markus */ 1673 channel_close_all(); 1674 1675 /* 1676 * Close any extra file descriptors. Note that there may still be 1677 * descriptors left by system functions. They will be closed later. 1678 */ 1679 endpwent(); 1680 1681 /* 1682 * Close any extra open file descriptors so that we don't have them 1683 * hanging around in clients. Note that we want to do this after 1684 * initgroups, because at least on Solaris 2.3 it leaves file 1685 * descriptors open. 1686 */ 1687 closefrom(STDERR_FILENO + 1); 1688 } 1689 1690 /* 1691 * Performs common processing for the child, such as setting up the 1692 * environment, closing extra file descriptors, setting the user and group 1693 * ids, and executing the command or shell. 1694 */ 1695 #define ARGV_MAX 10 1696 void 1697 do_child(Session *s, const char *command) 1698 { 1699 extern char **environ; 1700 char **env; 1701 char *argv[ARGV_MAX]; 1702 const char *shell, *shell0, *hostname = NULL; 1703 struct passwd *pw = s->pw; 1704 int r = 0; 1705 1706 /* remove hostkey from the child's memory */ 1707 destroy_sensitive_data(); 1708 1709 /* Force a password change */ 1710 if (s->authctxt->force_pwchange) { 1711 do_setusercontext(pw); 1712 child_close_fds(); 1713 do_pwchange(s); 1714 exit(1); 1715 } 1716 1717 /* login(1) is only called if we execute the login shell */ 1718 if (options.use_login && command != NULL) 1719 options.use_login = 0; 1720 1721 #ifdef _UNICOS 1722 cray_setup(pw->pw_uid, pw->pw_name, command); 1723 #endif /* _UNICOS */ 1724 1725 /* 1726 * Login(1) does this as well, and it needs uid 0 for the "-h" 1727 * switch, so we let login(1) to this for us. 1728 */ 1729 if (!options.use_login) { 1730 #ifdef HAVE_OSF_SIA 1731 session_setup_sia(pw, s->ttyfd == -1 ? NULL : s->tty); 1732 if (!check_quietlogin(s, command)) 1733 do_motd(); 1734 #else /* HAVE_OSF_SIA */ 1735 /* When PAM is enabled we rely on it to do the nologin check */ 1736 if (!options.use_pam) 1737 do_nologin(pw); 1738 do_setusercontext(pw); 1739 /* 1740 * PAM session modules in do_setusercontext may have 1741 * generated messages, so if this in an interactive 1742 * login then display them too. 1743 */ 1744 if (!check_quietlogin(s, command)) 1745 display_loginmsg(); 1746 #endif /* HAVE_OSF_SIA */ 1747 } 1748 1749 #ifdef USE_PAM 1750 if (options.use_pam && !options.use_login && !is_pam_session_open()) { 1751 debug3("PAM session not opened, exiting"); 1752 display_loginmsg(); 1753 exit(254); 1754 } 1755 #endif 1756 1757 /* 1758 * Get the shell from the password data. An empty shell field is 1759 * legal, and means /bin/sh. 1760 */ 1761 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; 1762 1763 /* 1764 * Make sure $SHELL points to the shell from the password file, 1765 * even if shell is overridden from login.conf 1766 */ 1767 env = do_setup_env(s, shell); 1768 1769 #ifdef HAVE_LOGIN_CAP 1770 shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell); 1771 #endif 1772 1773 /* we have to stash the hostname before we close our socket. */ 1774 if (options.use_login) 1775 hostname = get_remote_name_or_ip(utmp_len, 1776 options.use_dns); 1777 /* 1778 * Close the connection descriptors; note that this is the child, and 1779 * the server will still have the socket open, and it is important 1780 * that we do not shutdown it. Note that the descriptors cannot be 1781 * closed before building the environment, as we call 1782 * get_remote_ipaddr there. 1783 */ 1784 child_close_fds(); 1785 1786 /* 1787 * Must take new environment into use so that .ssh/rc, 1788 * /etc/ssh/sshrc and xauth are run in the proper environment. 1789 */ 1790 environ = env; 1791 1792 #if defined(KRB5) && defined(USE_AFS) 1793 /* 1794 * At this point, we check to see if AFS is active and if we have 1795 * a valid Kerberos 5 TGT. If so, it seems like a good idea to see 1796 * if we can (and need to) extend the ticket into an AFS token. If 1797 * we don't do this, we run into potential problems if the user's 1798 * home directory is in AFS and it's not world-readable. 1799 */ 1800 1801 if (options.kerberos_get_afs_token && k_hasafs() && 1802 (s->authctxt->krb5_ctx != NULL)) { 1803 char cell[64]; 1804 1805 debug("Getting AFS token"); 1806 1807 k_setpag(); 1808 1809 if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0) 1810 krb5_afslog(s->authctxt->krb5_ctx, 1811 s->authctxt->krb5_fwd_ccache, cell, NULL); 1812 1813 krb5_afslog_home(s->authctxt->krb5_ctx, 1814 s->authctxt->krb5_fwd_ccache, NULL, NULL, pw->pw_dir); 1815 } 1816 #endif 1817 1818 /* Change current directory to the user's home directory. */ 1819 if (chdir(pw->pw_dir) < 0) { 1820 /* Suppress missing homedir warning for chroot case */ 1821 #ifdef HAVE_LOGIN_CAP 1822 r = login_getcapbool(lc, "requirehome", 0); 1823 #endif 1824 if (r || !in_chroot) { 1825 fprintf(stderr, "Could not chdir to home " 1826 "directory %s: %s\n", pw->pw_dir, 1827 strerror(errno)); 1828 } 1829 if (r) 1830 exit(1); 1831 } 1832 1833 closefrom(STDERR_FILENO + 1); 1834 1835 if (!options.use_login) 1836 do_rc_files(s, shell); 1837 1838 /* restore SIGPIPE for child */ 1839 signal(SIGPIPE, SIG_DFL); 1840 1841 if (s->is_subsystem == SUBSYSTEM_INT_SFTP_ERROR) { 1842 printf("This service allows sftp connections only.\n"); 1843 fflush(NULL); 1844 exit(1); 1845 } else if (s->is_subsystem == SUBSYSTEM_INT_SFTP) { 1846 extern int optind, optreset; 1847 int i; 1848 char *p, *args; 1849 1850 setproctitle("%s@%s", s->pw->pw_name, INTERNAL_SFTP_NAME); 1851 args = xstrdup(command ? command : "sftp-server"); 1852 for (i = 0, (p = strtok(args, " ")); p; (p = strtok(NULL, " "))) 1853 if (i < ARGV_MAX - 1) 1854 argv[i++] = p; 1855 argv[i] = NULL; 1856 optind = optreset = 1; 1857 __progname = argv[0]; 1858 #ifdef WITH_SELINUX 1859 ssh_selinux_change_context("sftpd_t"); 1860 #endif 1861 exit(sftp_server_main(i, argv, s->pw)); 1862 } 1863 1864 fflush(NULL); 1865 1866 if (options.use_login) { 1867 launch_login(pw, hostname); 1868 /* NEVERREACHED */ 1869 } 1870 1871 /* Get the last component of the shell name. */ 1872 if ((shell0 = strrchr(shell, '/')) != NULL) 1873 shell0++; 1874 else 1875 shell0 = shell; 1876 1877 /* 1878 * If we have no command, execute the shell. In this case, the shell 1879 * name to be passed in argv[0] is preceded by '-' to indicate that 1880 * this is a login shell. 1881 */ 1882 if (!command) { 1883 char argv0[256]; 1884 1885 /* Start the shell. Set initial character to '-'. */ 1886 argv0[0] = '-'; 1887 1888 if (strlcpy(argv0 + 1, shell0, sizeof(argv0) - 1) 1889 >= sizeof(argv0) - 1) { 1890 errno = EINVAL; 1891 perror(shell); 1892 exit(1); 1893 } 1894 1895 /* Execute the shell. */ 1896 argv[0] = argv0; 1897 argv[1] = NULL; 1898 execve(shell, argv, env); 1899 1900 /* Executing the shell failed. */ 1901 perror(shell); 1902 exit(1); 1903 } 1904 /* 1905 * Execute the command using the user's shell. This uses the -c 1906 * option to execute the command. 1907 */ 1908 argv[0] = (char *) shell0; 1909 argv[1] = "-c"; 1910 argv[2] = (char *) command; 1911 argv[3] = NULL; 1912 execve(shell, argv, env); 1913 perror(shell); 1914 exit(1); 1915 } 1916 1917 void 1918 session_unused(int id) 1919 { 1920 debug3("%s: session id %d unused", __func__, id); 1921 if (id >= options.max_sessions || 1922 id >= sessions_nalloc) { 1923 fatal("%s: insane session id %d (max %d nalloc %d)", 1924 __func__, id, options.max_sessions, sessions_nalloc); 1925 } 1926 memset(&sessions[id], 0, sizeof(*sessions)); 1927 sessions[id].self = id; 1928 sessions[id].used = 0; 1929 sessions[id].chanid = -1; 1930 sessions[id].ptyfd = -1; 1931 sessions[id].ttyfd = -1; 1932 sessions[id].ptymaster = -1; 1933 sessions[id].x11_chanids = NULL; 1934 sessions[id].next_unused = sessions_first_unused; 1935 sessions_first_unused = id; 1936 } 1937 1938 Session * 1939 session_new(void) 1940 { 1941 Session *s, *tmp; 1942 1943 if (sessions_first_unused == -1) { 1944 if (sessions_nalloc >= options.max_sessions) 1945 return NULL; 1946 debug2("%s: allocate (allocated %d max %d)", 1947 __func__, sessions_nalloc, options.max_sessions); 1948 tmp = xreallocarray(sessions, sessions_nalloc + 1, 1949 sizeof(*sessions)); 1950 if (tmp == NULL) { 1951 error("%s: cannot allocate %d sessions", 1952 __func__, sessions_nalloc + 1); 1953 return NULL; 1954 } 1955 sessions = tmp; 1956 session_unused(sessions_nalloc++); 1957 } 1958 1959 if (sessions_first_unused >= sessions_nalloc || 1960 sessions_first_unused < 0) { 1961 fatal("%s: insane first_unused %d max %d nalloc %d", 1962 __func__, sessions_first_unused, options.max_sessions, 1963 sessions_nalloc); 1964 } 1965 1966 s = &sessions[sessions_first_unused]; 1967 if (s->used) { 1968 fatal("%s: session %d already used", 1969 __func__, sessions_first_unused); 1970 } 1971 sessions_first_unused = s->next_unused; 1972 s->used = 1; 1973 s->next_unused = -1; 1974 debug("session_new: session %d", s->self); 1975 1976 return s; 1977 } 1978 1979 static void 1980 session_dump(void) 1981 { 1982 int i; 1983 for (i = 0; i < sessions_nalloc; i++) { 1984 Session *s = &sessions[i]; 1985 1986 debug("dump: used %d next_unused %d session %d %p " 1987 "channel %d pid %ld", 1988 s->used, 1989 s->next_unused, 1990 s->self, 1991 s, 1992 s->chanid, 1993 (long)s->pid); 1994 } 1995 } 1996 1997 int 1998 session_open(Authctxt *authctxt, int chanid) 1999 { 2000 Session *s = session_new(); 2001 debug("session_open: channel %d", chanid); 2002 if (s == NULL) { 2003 error("no more sessions"); 2004 return 0; 2005 } 2006 s->authctxt = authctxt; 2007 s->pw = authctxt->pw; 2008 if (s->pw == NULL || !authctxt->valid) 2009 fatal("no user for session %d", s->self); 2010 debug("session_open: session %d: link with channel %d", s->self, chanid); 2011 s->chanid = chanid; 2012 return 1; 2013 } 2014 2015 Session * 2016 session_by_tty(char *tty) 2017 { 2018 int i; 2019 for (i = 0; i < sessions_nalloc; i++) { 2020 Session *s = &sessions[i]; 2021 if (s->used && s->ttyfd != -1 && strcmp(s->tty, tty) == 0) { 2022 debug("session_by_tty: session %d tty %s", i, tty); 2023 return s; 2024 } 2025 } 2026 debug("session_by_tty: unknown tty %.100s", tty); 2027 session_dump(); 2028 return NULL; 2029 } 2030 2031 static Session * 2032 session_by_channel(int id) 2033 { 2034 int i; 2035 for (i = 0; i < sessions_nalloc; i++) { 2036 Session *s = &sessions[i]; 2037 if (s->used && s->chanid == id) { 2038 debug("session_by_channel: session %d channel %d", 2039 i, id); 2040 return s; 2041 } 2042 } 2043 debug("session_by_channel: unknown channel %d", id); 2044 session_dump(); 2045 return NULL; 2046 } 2047 2048 static Session * 2049 session_by_x11_channel(int id) 2050 { 2051 int i, j; 2052 2053 for (i = 0; i < sessions_nalloc; i++) { 2054 Session *s = &sessions[i]; 2055 2056 if (s->x11_chanids == NULL || !s->used) 2057 continue; 2058 for (j = 0; s->x11_chanids[j] != -1; j++) { 2059 if (s->x11_chanids[j] == id) { 2060 debug("session_by_x11_channel: session %d " 2061 "channel %d", s->self, id); 2062 return s; 2063 } 2064 } 2065 } 2066 debug("session_by_x11_channel: unknown channel %d", id); 2067 session_dump(); 2068 return NULL; 2069 } 2070 2071 static Session * 2072 session_by_pid(pid_t pid) 2073 { 2074 int i; 2075 debug("session_by_pid: pid %ld", (long)pid); 2076 for (i = 0; i < sessions_nalloc; i++) { 2077 Session *s = &sessions[i]; 2078 if (s->used && s->pid == pid) 2079 return s; 2080 } 2081 error("session_by_pid: unknown pid %ld", (long)pid); 2082 session_dump(); 2083 return NULL; 2084 } 2085 2086 static int 2087 session_window_change_req(Session *s) 2088 { 2089 s->col = packet_get_int(); 2090 s->row = packet_get_int(); 2091 s->xpixel = packet_get_int(); 2092 s->ypixel = packet_get_int(); 2093 packet_check_eom(); 2094 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 2095 return 1; 2096 } 2097 2098 static int 2099 session_pty_req(Session *s) 2100 { 2101 u_int len; 2102 int n_bytes; 2103 2104 if (no_pty_flag || !options.permit_tty) { 2105 debug("Allocating a pty not permitted for this authentication."); 2106 return 0; 2107 } 2108 if (s->ttyfd != -1) { 2109 packet_disconnect("Protocol error: you already have a pty."); 2110 return 0; 2111 } 2112 2113 s->term = packet_get_string(&len); 2114 2115 if (compat20) { 2116 s->col = packet_get_int(); 2117 s->row = packet_get_int(); 2118 } else { 2119 s->row = packet_get_int(); 2120 s->col = packet_get_int(); 2121 } 2122 s->xpixel = packet_get_int(); 2123 s->ypixel = packet_get_int(); 2124 2125 if (strcmp(s->term, "") == 0) { 2126 free(s->term); 2127 s->term = NULL; 2128 } 2129 2130 /* Allocate a pty and open it. */ 2131 debug("Allocating pty."); 2132 if (!PRIVSEP(pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, 2133 sizeof(s->tty)))) { 2134 free(s->term); 2135 s->term = NULL; 2136 s->ptyfd = -1; 2137 s->ttyfd = -1; 2138 error("session_pty_req: session %d alloc failed", s->self); 2139 return 0; 2140 } 2141 debug("session_pty_req: session %d alloc %s", s->self, s->tty); 2142 2143 /* for SSH1 the tty modes length is not given */ 2144 if (!compat20) 2145 n_bytes = packet_remaining(); 2146 tty_parse_modes(s->ttyfd, &n_bytes); 2147 2148 if (!use_privsep) 2149 pty_setowner(s->pw, s->tty); 2150 2151 /* Set window size from the packet. */ 2152 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 2153 2154 packet_check_eom(); 2155 session_proctitle(s); 2156 return 1; 2157 } 2158 2159 static int 2160 session_subsystem_req(Session *s) 2161 { 2162 struct stat st; 2163 u_int len; 2164 int success = 0; 2165 char *prog, *cmd; 2166 u_int i; 2167 2168 s->subsys = packet_get_string(&len); 2169 packet_check_eom(); 2170 debug2("subsystem request for %.100s by user %s", s->subsys, 2171 s->pw->pw_name); 2172 2173 for (i = 0; i < options.num_subsystems; i++) { 2174 if (strcmp(s->subsys, options.subsystem_name[i]) == 0) { 2175 prog = options.subsystem_command[i]; 2176 cmd = options.subsystem_args[i]; 2177 if (strcmp(INTERNAL_SFTP_NAME, prog) == 0) { 2178 s->is_subsystem = SUBSYSTEM_INT_SFTP; 2179 debug("subsystem: %s", prog); 2180 } else { 2181 if (stat(prog, &st) < 0) 2182 debug("subsystem: cannot stat %s: %s", 2183 prog, strerror(errno)); 2184 s->is_subsystem = SUBSYSTEM_EXT; 2185 debug("subsystem: exec() %s", cmd); 2186 } 2187 success = do_exec(s, cmd) == 0; 2188 break; 2189 } 2190 } 2191 2192 if (!success) 2193 logit("subsystem request for %.100s by user %s failed, " 2194 "subsystem not found", s->subsys, s->pw->pw_name); 2195 2196 return success; 2197 } 2198 2199 static int 2200 session_x11_req(Session *s) 2201 { 2202 int success; 2203 2204 if (s->auth_proto != NULL || s->auth_data != NULL) { 2205 error("session_x11_req: session %d: " 2206 "x11 forwarding already active", s->self); 2207 return 0; 2208 } 2209 s->single_connection = packet_get_char(); 2210 s->auth_proto = packet_get_string(NULL); 2211 s->auth_data = packet_get_string(NULL); 2212 s->screen = packet_get_int(); 2213 packet_check_eom(); 2214 2215 if (xauth_valid_string(s->auth_proto) && 2216 xauth_valid_string(s->auth_data)) 2217 success = session_setup_x11fwd(s); 2218 else { 2219 success = 0; 2220 error("Invalid X11 forwarding data"); 2221 } 2222 if (!success) { 2223 free(s->auth_proto); 2224 free(s->auth_data); 2225 s->auth_proto = NULL; 2226 s->auth_data = NULL; 2227 } 2228 return success; 2229 } 2230 2231 static int 2232 session_shell_req(Session *s) 2233 { 2234 packet_check_eom(); 2235 return do_exec(s, NULL) == 0; 2236 } 2237 2238 static int 2239 session_exec_req(Session *s) 2240 { 2241 u_int len, success; 2242 2243 char *command = packet_get_string(&len); 2244 packet_check_eom(); 2245 success = do_exec(s, command) == 0; 2246 free(command); 2247 return success; 2248 } 2249 2250 static int 2251 session_break_req(Session *s) 2252 { 2253 2254 packet_get_int(); /* ignored */ 2255 packet_check_eom(); 2256 2257 if (s->ptymaster == -1 || tcsendbreak(s->ptymaster, 0) < 0) 2258 return 0; 2259 return 1; 2260 } 2261 2262 static int 2263 session_env_req(Session *s) 2264 { 2265 char *name, *val; 2266 u_int name_len, val_len, i; 2267 2268 name = packet_get_cstring(&name_len); 2269 val = packet_get_cstring(&val_len); 2270 packet_check_eom(); 2271 2272 /* Don't set too many environment variables */ 2273 if (s->num_env > 128) { 2274 debug2("Ignoring env request %s: too many env vars", name); 2275 goto fail; 2276 } 2277 2278 for (i = 0; i < options.num_accept_env; i++) { 2279 if (match_pattern(name, options.accept_env[i])) { 2280 debug2("Setting env %d: %s=%s", s->num_env, name, val); 2281 s->env = xreallocarray(s->env, s->num_env + 1, 2282 sizeof(*s->env)); 2283 s->env[s->num_env].name = name; 2284 s->env[s->num_env].val = val; 2285 s->num_env++; 2286 return (1); 2287 } 2288 } 2289 debug2("Ignoring env request %s: disallowed name", name); 2290 2291 fail: 2292 free(name); 2293 free(val); 2294 return (0); 2295 } 2296 2297 static int 2298 session_auth_agent_req(Session *s) 2299 { 2300 static int called = 0; 2301 packet_check_eom(); 2302 if (no_agent_forwarding_flag || !options.allow_agent_forwarding) { 2303 debug("session_auth_agent_req: no_agent_forwarding_flag"); 2304 return 0; 2305 } 2306 if (called) { 2307 return 0; 2308 } else { 2309 called = 1; 2310 return auth_input_request_forwarding(s->pw); 2311 } 2312 } 2313 2314 int 2315 session_input_channel_req(Channel *c, const char *rtype) 2316 { 2317 int success = 0; 2318 Session *s; 2319 2320 if ((s = session_by_channel(c->self)) == NULL) { 2321 logit("session_input_channel_req: no session %d req %.100s", 2322 c->self, rtype); 2323 return 0; 2324 } 2325 debug("session_input_channel_req: session %d req %s", s->self, rtype); 2326 2327 /* 2328 * a session is in LARVAL state until a shell, a command 2329 * or a subsystem is executed 2330 */ 2331 if (c->type == SSH_CHANNEL_LARVAL) { 2332 if (strcmp(rtype, "shell") == 0) { 2333 success = session_shell_req(s); 2334 } else if (strcmp(rtype, "exec") == 0) { 2335 success = session_exec_req(s); 2336 } else if (strcmp(rtype, "pty-req") == 0) { 2337 success = session_pty_req(s); 2338 } else if (strcmp(rtype, "x11-req") == 0) { 2339 success = session_x11_req(s); 2340 } else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) { 2341 success = session_auth_agent_req(s); 2342 } else if (strcmp(rtype, "subsystem") == 0) { 2343 success = session_subsystem_req(s); 2344 } else if (strcmp(rtype, "env") == 0) { 2345 success = session_env_req(s); 2346 } 2347 } 2348 if (strcmp(rtype, "window-change") == 0) { 2349 success = session_window_change_req(s); 2350 } else if (strcmp(rtype, "break") == 0) { 2351 success = session_break_req(s); 2352 } 2353 2354 return success; 2355 } 2356 2357 void 2358 session_set_fds(Session *s, int fdin, int fdout, int fderr, int ignore_fderr, 2359 int is_tty) 2360 { 2361 if (!compat20) 2362 fatal("session_set_fds: called for proto != 2.0"); 2363 /* 2364 * now that have a child and a pipe to the child, 2365 * we can activate our channel and register the fd's 2366 */ 2367 if (s->chanid == -1) 2368 fatal("no channel for session %d", s->self); 2369 channel_set_fds(s->chanid, 2370 fdout, fdin, fderr, 2371 ignore_fderr ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ, 2372 1, is_tty, CHAN_SES_WINDOW_DEFAULT); 2373 } 2374 2375 /* 2376 * Function to perform pty cleanup. Also called if we get aborted abnormally 2377 * (e.g., due to a dropped connection). 2378 */ 2379 void 2380 session_pty_cleanup2(Session *s) 2381 { 2382 if (s == NULL) { 2383 error("session_pty_cleanup: no session"); 2384 return; 2385 } 2386 if (s->ttyfd == -1) 2387 return; 2388 2389 debug("session_pty_cleanup: session %d release %s", s->self, s->tty); 2390 2391 /* Record that the user has logged out. */ 2392 if (s->pid != 0) 2393 record_logout(s->pid, s->tty, s->pw->pw_name); 2394 2395 /* Release the pseudo-tty. */ 2396 if (getuid() == 0) 2397 pty_release(s->tty); 2398 2399 /* 2400 * Close the server side of the socket pairs. We must do this after 2401 * the pty cleanup, so that another process doesn't get this pty 2402 * while we're still cleaning up. 2403 */ 2404 if (s->ptymaster != -1 && close(s->ptymaster) < 0) 2405 error("close(s->ptymaster/%d): %s", 2406 s->ptymaster, strerror(errno)); 2407 2408 /* unlink pty from session */ 2409 s->ttyfd = -1; 2410 } 2411 2412 void 2413 session_pty_cleanup(Session *s) 2414 { 2415 PRIVSEP(session_pty_cleanup2(s)); 2416 } 2417 2418 static char * 2419 sig2name(int sig) 2420 { 2421 #define SSH_SIG(x) if (sig == SIG ## x) return #x 2422 SSH_SIG(ABRT); 2423 SSH_SIG(ALRM); 2424 SSH_SIG(FPE); 2425 SSH_SIG(HUP); 2426 SSH_SIG(ILL); 2427 SSH_SIG(INT); 2428 SSH_SIG(KILL); 2429 SSH_SIG(PIPE); 2430 SSH_SIG(QUIT); 2431 SSH_SIG(SEGV); 2432 SSH_SIG(TERM); 2433 SSH_SIG(USR1); 2434 SSH_SIG(USR2); 2435 #undef SSH_SIG 2436 return "SIG@openssh.com"; 2437 } 2438 2439 static void 2440 session_close_x11(int id) 2441 { 2442 Channel *c; 2443 2444 if ((c = channel_by_id(id)) == NULL) { 2445 debug("session_close_x11: x11 channel %d missing", id); 2446 } else { 2447 /* Detach X11 listener */ 2448 debug("session_close_x11: detach x11 channel %d", id); 2449 channel_cancel_cleanup(id); 2450 if (c->ostate != CHAN_OUTPUT_CLOSED) 2451 chan_mark_dead(c); 2452 } 2453 } 2454 2455 static void 2456 session_close_single_x11(int id, void *arg) 2457 { 2458 Session *s; 2459 u_int i; 2460 2461 debug3("session_close_single_x11: channel %d", id); 2462 channel_cancel_cleanup(id); 2463 if ((s = session_by_x11_channel(id)) == NULL) 2464 fatal("session_close_single_x11: no x11 channel %d", id); 2465 for (i = 0; s->x11_chanids[i] != -1; i++) { 2466 debug("session_close_single_x11: session %d: " 2467 "closing channel %d", s->self, s->x11_chanids[i]); 2468 /* 2469 * The channel "id" is already closing, but make sure we 2470 * close all of its siblings. 2471 */ 2472 if (s->x11_chanids[i] != id) 2473 session_close_x11(s->x11_chanids[i]); 2474 } 2475 free(s->x11_chanids); 2476 s->x11_chanids = NULL; 2477 free(s->display); 2478 s->display = NULL; 2479 free(s->auth_proto); 2480 s->auth_proto = NULL; 2481 free(s->auth_data); 2482 s->auth_data = NULL; 2483 free(s->auth_display); 2484 s->auth_display = NULL; 2485 } 2486 2487 static void 2488 session_exit_message(Session *s, int status) 2489 { 2490 Channel *c; 2491 2492 if ((c = channel_lookup(s->chanid)) == NULL) 2493 fatal("session_exit_message: session %d: no channel %d", 2494 s->self, s->chanid); 2495 debug("session_exit_message: session %d channel %d pid %ld", 2496 s->self, s->chanid, (long)s->pid); 2497 2498 if (WIFEXITED(status)) { 2499 channel_request_start(s->chanid, "exit-status", 0); 2500 packet_put_int(WEXITSTATUS(status)); 2501 packet_send(); 2502 } else if (WIFSIGNALED(status)) { 2503 channel_request_start(s->chanid, "exit-signal", 0); 2504 packet_put_cstring(sig2name(WTERMSIG(status))); 2505 #ifdef WCOREDUMP 2506 packet_put_char(WCOREDUMP(status)? 1 : 0); 2507 #else /* WCOREDUMP */ 2508 packet_put_char(0); 2509 #endif /* WCOREDUMP */ 2510 packet_put_cstring(""); 2511 packet_put_cstring(""); 2512 packet_send(); 2513 } else { 2514 /* Some weird exit cause. Just exit. */ 2515 packet_disconnect("wait returned status %04x.", status); 2516 } 2517 2518 /* disconnect channel */ 2519 debug("session_exit_message: release channel %d", s->chanid); 2520 2521 /* 2522 * Adjust cleanup callback attachment to send close messages when 2523 * the channel gets EOF. The session will be then be closed 2524 * by session_close_by_channel when the childs close their fds. 2525 */ 2526 channel_register_cleanup(c->self, session_close_by_channel, 1); 2527 2528 /* 2529 * emulate a write failure with 'chan_write_failed', nobody will be 2530 * interested in data we write. 2531 * Note that we must not call 'chan_read_failed', since there could 2532 * be some more data waiting in the pipe. 2533 */ 2534 if (c->ostate != CHAN_OUTPUT_CLOSED) 2535 chan_write_failed(c); 2536 } 2537 2538 void 2539 session_close(Session *s) 2540 { 2541 u_int i; 2542 2543 verbose("Close session: user %s from %.200s port %d id %d", 2544 s->pw->pw_name, 2545 get_remote_ipaddr(), 2546 get_remote_port(), 2547 s->self); 2548 2549 if (s->ttyfd != -1) 2550 session_pty_cleanup(s); 2551 free(s->term); 2552 free(s->display); 2553 free(s->x11_chanids); 2554 free(s->auth_display); 2555 free(s->auth_data); 2556 free(s->auth_proto); 2557 free(s->subsys); 2558 if (s->env != NULL) { 2559 for (i = 0; i < s->num_env; i++) { 2560 free(s->env[i].name); 2561 free(s->env[i].val); 2562 } 2563 free(s->env); 2564 } 2565 session_proctitle(s); 2566 session_unused(s->self); 2567 } 2568 2569 void 2570 session_close_by_pid(pid_t pid, int status) 2571 { 2572 Session *s = session_by_pid(pid); 2573 if (s == NULL) { 2574 debug("session_close_by_pid: no session for pid %ld", 2575 (long)pid); 2576 return; 2577 } 2578 if (s->chanid != -1) 2579 session_exit_message(s, status); 2580 if (s->ttyfd != -1) 2581 session_pty_cleanup(s); 2582 s->pid = 0; 2583 } 2584 2585 /* 2586 * this is called when a channel dies before 2587 * the session 'child' itself dies 2588 */ 2589 void 2590 session_close_by_channel(int id, void *arg) 2591 { 2592 Session *s = session_by_channel(id); 2593 u_int i; 2594 2595 if (s == NULL) { 2596 debug("session_close_by_channel: no session for id %d", id); 2597 return; 2598 } 2599 debug("session_close_by_channel: channel %d child %ld", 2600 id, (long)s->pid); 2601 if (s->pid != 0) { 2602 debug("session_close_by_channel: channel %d: has child", id); 2603 /* 2604 * delay detach of session, but release pty, since 2605 * the fd's to the child are already closed 2606 */ 2607 if (s->ttyfd != -1) 2608 session_pty_cleanup(s); 2609 return; 2610 } 2611 /* detach by removing callback */ 2612 channel_cancel_cleanup(s->chanid); 2613 2614 /* Close any X11 listeners associated with this session */ 2615 if (s->x11_chanids != NULL) { 2616 for (i = 0; s->x11_chanids[i] != -1; i++) { 2617 session_close_x11(s->x11_chanids[i]); 2618 s->x11_chanids[i] = -1; 2619 } 2620 } 2621 2622 s->chanid = -1; 2623 session_close(s); 2624 } 2625 2626 void 2627 session_destroy_all(void (*closefunc)(Session *)) 2628 { 2629 int i; 2630 for (i = 0; i < sessions_nalloc; i++) { 2631 Session *s = &sessions[i]; 2632 if (s->used) { 2633 if (closefunc != NULL) 2634 closefunc(s); 2635 else 2636 session_close(s); 2637 } 2638 } 2639 } 2640 2641 static char * 2642 session_tty_list(void) 2643 { 2644 static char buf[1024]; 2645 int i; 2646 char *cp; 2647 2648 buf[0] = '\0'; 2649 for (i = 0; i < sessions_nalloc; i++) { 2650 Session *s = &sessions[i]; 2651 if (s->used && s->ttyfd != -1) { 2652 2653 if (strncmp(s->tty, "/dev/", 5) != 0) { 2654 cp = strrchr(s->tty, '/'); 2655 cp = (cp == NULL) ? s->tty : cp + 1; 2656 } else 2657 cp = s->tty + 5; 2658 2659 if (buf[0] != '\0') 2660 strlcat(buf, ",", sizeof buf); 2661 strlcat(buf, cp, sizeof buf); 2662 } 2663 } 2664 if (buf[0] == '\0') 2665 strlcpy(buf, "notty", sizeof buf); 2666 return buf; 2667 } 2668 2669 void 2670 session_proctitle(Session *s) 2671 { 2672 if (s->pw == NULL) 2673 error("no user for session %d", s->self); 2674 else 2675 setproctitle("%s@%s", s->pw->pw_name, session_tty_list()); 2676 } 2677 2678 int 2679 session_setup_x11fwd(Session *s) 2680 { 2681 struct stat st; 2682 char display[512], auth_display[512]; 2683 char hostname[NI_MAXHOST]; 2684 u_int i; 2685 2686 if (no_x11_forwarding_flag) { 2687 packet_send_debug("X11 forwarding disabled in user configuration file."); 2688 return 0; 2689 } 2690 if (!options.x11_forwarding) { 2691 debug("X11 forwarding disabled in server configuration file."); 2692 return 0; 2693 } 2694 if (options.xauth_location == NULL || 2695 (stat(options.xauth_location, &st) == -1)) { 2696 packet_send_debug("No xauth program; cannot forward with spoofing."); 2697 return 0; 2698 } 2699 if (options.use_login) { 2700 packet_send_debug("X11 forwarding disabled; " 2701 "not compatible with UseLogin=yes."); 2702 return 0; 2703 } 2704 if (s->display != NULL) { 2705 debug("X11 display already set."); 2706 return 0; 2707 } 2708 if (x11_create_display_inet(options.x11_display_offset, 2709 options.x11_use_localhost, s->single_connection, 2710 &s->display_number, &s->x11_chanids) == -1) { 2711 debug("x11_create_display_inet failed."); 2712 return 0; 2713 } 2714 for (i = 0; s->x11_chanids[i] != -1; i++) { 2715 channel_register_cleanup(s->x11_chanids[i], 2716 session_close_single_x11, 0); 2717 } 2718 2719 /* Set up a suitable value for the DISPLAY variable. */ 2720 if (gethostname(hostname, sizeof(hostname)) < 0) 2721 fatal("gethostname: %.100s", strerror(errno)); 2722 /* 2723 * auth_display must be used as the displayname when the 2724 * authorization entry is added with xauth(1). This will be 2725 * different than the DISPLAY string for localhost displays. 2726 */ 2727 if (options.x11_use_localhost) { 2728 snprintf(display, sizeof display, "localhost:%u.%u", 2729 s->display_number, s->screen); 2730 snprintf(auth_display, sizeof auth_display, "unix:%u.%u", 2731 s->display_number, s->screen); 2732 s->display = xstrdup(display); 2733 s->auth_display = xstrdup(auth_display); 2734 } else { 2735 #ifdef IPADDR_IN_DISPLAY 2736 struct hostent *he; 2737 struct in_addr my_addr; 2738 2739 he = gethostbyname(hostname); 2740 if (he == NULL) { 2741 error("Can't get IP address for X11 DISPLAY."); 2742 packet_send_debug("Can't get IP address for X11 DISPLAY."); 2743 return 0; 2744 } 2745 memcpy(&my_addr, he->h_addr_list[0], sizeof(struct in_addr)); 2746 snprintf(display, sizeof display, "%.50s:%u.%u", inet_ntoa(my_addr), 2747 s->display_number, s->screen); 2748 #else 2749 snprintf(display, sizeof display, "%.400s:%u.%u", hostname, 2750 s->display_number, s->screen); 2751 #endif 2752 s->display = xstrdup(display); 2753 s->auth_display = xstrdup(display); 2754 } 2755 2756 return 1; 2757 } 2758 2759 static void 2760 do_authenticated2(Authctxt *authctxt) 2761 { 2762 server_loop2(authctxt); 2763 } 2764 2765 void 2766 do_cleanup(Authctxt *authctxt) 2767 { 2768 static int called = 0; 2769 2770 debug("do_cleanup"); 2771 2772 /* no cleanup if we're in the child for login shell */ 2773 if (is_child) 2774 return; 2775 2776 /* avoid double cleanup */ 2777 if (called) 2778 return; 2779 called = 1; 2780 2781 if (authctxt == NULL) 2782 return; 2783 2784 #ifdef USE_PAM 2785 if (options.use_pam) { 2786 sshpam_cleanup(); 2787 sshpam_thread_cleanup(); 2788 } 2789 #endif 2790 2791 if (!authctxt->authenticated) 2792 return; 2793 2794 #ifdef KRB5 2795 if (options.kerberos_ticket_cleanup && 2796 authctxt->krb5_ctx) 2797 krb5_cleanup_proc(authctxt); 2798 #endif 2799 2800 #ifdef GSSAPI 2801 if (compat20 && options.gss_cleanup_creds) 2802 ssh_gssapi_cleanup_creds(); 2803 #endif 2804 2805 /* remove agent socket */ 2806 auth_sock_cleanup_proc(authctxt->pw); 2807 2808 /* 2809 * Cleanup ptys/utmp only if privsep is disabled, 2810 * or if running in monitor. 2811 */ 2812 if (!use_privsep || mm_is_monitor()) 2813 session_destroy_all(session_pty_cleanup2); 2814 } 2815