1 /* $OpenBSD: session.c,v 1.282 2016/03/10 11:47:57 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 38 #include <sys/types.h> 39 #include <sys/param.h> 40 #ifdef HAVE_SYS_STAT_H 41 # include <sys/stat.h> 42 #endif 43 #include <sys/socket.h> 44 #include <sys/un.h> 45 #include <sys/wait.h> 46 47 #include <arpa/inet.h> 48 49 #include <ctype.h> 50 #include <errno.h> 51 #include <fcntl.h> 52 #include <grp.h> 53 #include <netdb.h> 54 #ifdef HAVE_PATHS_H 55 #include <paths.h> 56 #endif 57 #include <pwd.h> 58 #include <signal.h> 59 #include <stdarg.h> 60 #include <stdio.h> 61 #include <stdlib.h> 62 #include <string.h> 63 #include <unistd.h> 64 #include <limits.h> 65 66 #include "openbsd-compat/sys-queue.h" 67 #include "xmalloc.h" 68 #include "ssh.h" 69 #include "ssh1.h" 70 #include "ssh2.h" 71 #include "sshpty.h" 72 #include "packet.h" 73 #include "buffer.h" 74 #include "match.h" 75 #include "uidswap.h" 76 #include "compat.h" 77 #include "channels.h" 78 #include "key.h" 79 #include "cipher.h" 80 #ifdef GSSAPI 81 #include "ssh-gss.h" 82 #endif 83 #include "hostfile.h" 84 #include "auth.h" 85 #include "auth-options.h" 86 #include "authfd.h" 87 #include "pathnames.h" 88 #include "log.h" 89 #include "misc.h" 90 #include "servconf.h" 91 #include "sshlogin.h" 92 #include "serverloop.h" 93 #include "canohost.h" 94 #include "session.h" 95 #include "kex.h" 96 #include "monitor_wrap.h" 97 #include "sftp.h" 98 99 #if defined(KRB5) && defined(USE_AFS) 100 #include <kafs.h> 101 #endif 102 103 #ifdef WITH_SELINUX 104 #include <selinux/selinux.h> 105 #endif 106 107 #define IS_INTERNAL_SFTP(c) \ 108 (!strncmp(c, INTERNAL_SFTP_NAME, sizeof(INTERNAL_SFTP_NAME) - 1) && \ 109 (c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\0' || \ 110 c[sizeof(INTERNAL_SFTP_NAME) - 1] == ' ' || \ 111 c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\t')) 112 113 /* func */ 114 115 Session *session_new(void); 116 void session_set_fds(Session *, int, int, int, int, int); 117 void session_pty_cleanup(Session *); 118 void session_proctitle(Session *); 119 int session_setup_x11fwd(Session *); 120 int do_exec_pty(Session *, const char *); 121 int do_exec_no_pty(Session *, const char *); 122 int do_exec(Session *, const char *); 123 void do_login(Session *, const char *); 124 #ifdef LOGIN_NEEDS_UTMPX 125 static void do_pre_login(Session *s); 126 #endif 127 void do_child(Session *, const char *); 128 void do_motd(void); 129 int check_quietlogin(Session *, const char *); 130 131 static void do_authenticated1(Authctxt *); 132 static void do_authenticated2(Authctxt *); 133 134 static int session_pty_req(Session *); 135 136 /* import */ 137 extern ServerOptions options; 138 extern char *__progname; 139 extern int log_stderr; 140 extern int debug_flag; 141 extern u_int utmp_len; 142 extern int startup_pipe; 143 extern void destroy_sensitive_data(void); 144 extern Buffer loginmsg; 145 146 /* original command from peer. */ 147 const char *original_command = NULL; 148 149 /* data */ 150 static int sessions_first_unused = -1; 151 static int sessions_nalloc = 0; 152 static Session *sessions = NULL; 153 154 #define SUBSYSTEM_NONE 0 155 #define SUBSYSTEM_EXT 1 156 #define SUBSYSTEM_INT_SFTP 2 157 #define SUBSYSTEM_INT_SFTP_ERROR 3 158 159 #ifdef HAVE_LOGIN_CAP 160 login_cap_t *lc; 161 #endif 162 163 static int is_child = 0; 164 static int in_chroot = 0; 165 166 /* Name and directory of socket for authentication agent forwarding. */ 167 static char *auth_sock_name = NULL; 168 static char *auth_sock_dir = NULL; 169 170 /* removes the agent forwarding socket */ 171 172 static void 173 auth_sock_cleanup_proc(struct passwd *pw) 174 { 175 if (auth_sock_name != NULL) { 176 temporarily_use_uid(pw); 177 unlink(auth_sock_name); 178 rmdir(auth_sock_dir); 179 auth_sock_name = NULL; 180 restore_uid(); 181 } 182 } 183 184 static int 185 auth_input_request_forwarding(struct passwd * pw) 186 { 187 Channel *nc; 188 int sock = -1; 189 190 if (auth_sock_name != NULL) { 191 error("authentication forwarding requested twice."); 192 return 0; 193 } 194 195 /* Temporarily drop privileged uid for mkdir/bind. */ 196 temporarily_use_uid(pw); 197 198 /* Allocate a buffer for the socket name, and format the name. */ 199 auth_sock_dir = xstrdup("/tmp/ssh-XXXXXXXXXX"); 200 201 /* Create private directory for socket */ 202 if (mkdtemp(auth_sock_dir) == NULL) { 203 packet_send_debug("Agent forwarding disabled: " 204 "mkdtemp() failed: %.100s", strerror(errno)); 205 restore_uid(); 206 free(auth_sock_dir); 207 auth_sock_dir = NULL; 208 goto authsock_err; 209 } 210 211 xasprintf(&auth_sock_name, "%s/agent.%ld", 212 auth_sock_dir, (long) getpid()); 213 214 /* Start a Unix listener on auth_sock_name. */ 215 sock = unix_listener(auth_sock_name, SSH_LISTEN_BACKLOG, 0); 216 217 /* Restore the privileged uid. */ 218 restore_uid(); 219 220 /* Check for socket/bind/listen failure. */ 221 if (sock < 0) 222 goto authsock_err; 223 224 /* Allocate a channel for the authentication agent socket. */ 225 nc = channel_new("auth socket", 226 SSH_CHANNEL_AUTH_SOCKET, sock, sock, -1, 227 CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 228 0, "auth socket", 1); 229 nc->path = xstrdup(auth_sock_name); 230 return 1; 231 232 authsock_err: 233 free(auth_sock_name); 234 if (auth_sock_dir != NULL) { 235 rmdir(auth_sock_dir); 236 free(auth_sock_dir); 237 } 238 if (sock != -1) 239 close(sock); 240 auth_sock_name = NULL; 241 auth_sock_dir = NULL; 242 return 0; 243 } 244 245 static void 246 display_loginmsg(void) 247 { 248 if (buffer_len(&loginmsg) > 0) { 249 buffer_append(&loginmsg, "\0", 1); 250 printf("%s", (char *)buffer_ptr(&loginmsg)); 251 buffer_clear(&loginmsg); 252 } 253 } 254 255 void 256 do_authenticated(Authctxt *authctxt) 257 { 258 setproctitle("%s", authctxt->pw->pw_name); 259 260 /* setup the channel layer */ 261 /* XXX - streamlocal? */ 262 if (no_port_forwarding_flag || 263 (options.allow_tcp_forwarding & FORWARD_LOCAL) == 0) 264 channel_disable_adm_local_opens(); 265 else 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 /* Check untrusted xauth strings for metacharacters */ 279 static int 280 xauth_valid_string(const char *s) 281 { 282 size_t i; 283 284 for (i = 0; s[i] != '\0'; i++) { 285 if (!isalnum((u_char)s[i]) && 286 s[i] != '.' && s[i] != ':' && s[i] != '/' && 287 s[i] != '-' && s[i] != '_') 288 return 0; 289 } 290 return 1; 291 } 292 293 /* 294 * Prepares for an interactive session. This is called after the user has 295 * been successfully authenticated. During this message exchange, pseudo 296 * terminals are allocated, X11, TCP/IP, and authentication agent forwardings 297 * are requested, etc. 298 */ 299 static void 300 do_authenticated1(Authctxt *authctxt) 301 { 302 Session *s; 303 char *command; 304 int success, type, screen_flag; 305 int enable_compression_after_reply = 0; 306 u_int proto_len, data_len, dlen, compression_level = 0; 307 308 s = session_new(); 309 if (s == NULL) { 310 error("no more sessions"); 311 return; 312 } 313 s->authctxt = authctxt; 314 s->pw = authctxt->pw; 315 316 /* 317 * We stay in this loop until the client requests to execute a shell 318 * or a command. 319 */ 320 for (;;) { 321 success = 0; 322 323 /* Get a packet from the client. */ 324 type = packet_read(); 325 326 /* Process the packet. */ 327 switch (type) { 328 case SSH_CMSG_REQUEST_COMPRESSION: 329 compression_level = packet_get_int(); 330 packet_check_eom(); 331 if (compression_level < 1 || compression_level > 9) { 332 packet_send_debug("Received invalid compression level %d.", 333 compression_level); 334 break; 335 } 336 if (options.compression == COMP_NONE) { 337 debug2("compression disabled"); 338 break; 339 } 340 /* Enable compression after we have responded with SUCCESS. */ 341 enable_compression_after_reply = 1; 342 success = 1; 343 break; 344 345 case SSH_CMSG_REQUEST_PTY: 346 success = session_pty_req(s); 347 break; 348 349 case SSH_CMSG_X11_REQUEST_FORWARDING: 350 s->auth_proto = packet_get_string(&proto_len); 351 s->auth_data = packet_get_string(&data_len); 352 353 screen_flag = packet_get_protocol_flags() & 354 SSH_PROTOFLAG_SCREEN_NUMBER; 355 debug2("SSH_PROTOFLAG_SCREEN_NUMBER: %d", screen_flag); 356 357 if (packet_remaining() == 4) { 358 if (!screen_flag) 359 debug2("Buggy client: " 360 "X11 screen flag missing"); 361 s->screen = packet_get_int(); 362 } else { 363 s->screen = 0; 364 } 365 packet_check_eom(); 366 if (xauth_valid_string(s->auth_proto) && 367 xauth_valid_string(s->auth_data)) 368 success = session_setup_x11fwd(s); 369 else { 370 success = 0; 371 error("Invalid X11 forwarding data"); 372 } 373 if (!success) { 374 free(s->auth_proto); 375 free(s->auth_data); 376 s->auth_proto = NULL; 377 s->auth_data = NULL; 378 } 379 break; 380 381 case SSH_CMSG_AGENT_REQUEST_FORWARDING: 382 if (!options.allow_agent_forwarding || 383 no_agent_forwarding_flag || compat13) { 384 debug("Authentication agent forwarding not permitted for this authentication."); 385 break; 386 } 387 debug("Received authentication agent forwarding request."); 388 success = auth_input_request_forwarding(s->pw); 389 break; 390 391 case SSH_CMSG_PORT_FORWARD_REQUEST: 392 if (no_port_forwarding_flag) { 393 debug("Port forwarding not permitted for this authentication."); 394 break; 395 } 396 if (!(options.allow_tcp_forwarding & FORWARD_REMOTE)) { 397 debug("Port forwarding not permitted."); 398 break; 399 } 400 debug("Received TCP/IP port forwarding request."); 401 if (channel_input_port_forward_request(s->pw->pw_uid == 0, 402 &options.fwd_opts) < 0) { 403 debug("Port forwarding failed."); 404 break; 405 } 406 success = 1; 407 break; 408 409 case SSH_CMSG_MAX_PACKET_SIZE: 410 if (packet_set_maxsize(packet_get_int()) > 0) 411 success = 1; 412 break; 413 414 case SSH_CMSG_EXEC_SHELL: 415 case SSH_CMSG_EXEC_CMD: 416 if (type == SSH_CMSG_EXEC_CMD) { 417 command = packet_get_string(&dlen); 418 debug("Exec command '%.500s'", command); 419 if (do_exec(s, command) != 0) 420 packet_disconnect( 421 "command execution failed"); 422 free(command); 423 } else { 424 if (do_exec(s, NULL) != 0) 425 packet_disconnect( 426 "shell execution failed"); 427 } 428 packet_check_eom(); 429 session_close(s); 430 return; 431 432 default: 433 /* 434 * Any unknown messages in this phase are ignored, 435 * and a failure message is returned. 436 */ 437 logit("Unknown packet type received after authentication: %d", type); 438 } 439 packet_start(success ? SSH_SMSG_SUCCESS : SSH_SMSG_FAILURE); 440 packet_send(); 441 packet_write_wait(); 442 443 /* Enable compression now that we have replied if appropriate. */ 444 if (enable_compression_after_reply) { 445 enable_compression_after_reply = 0; 446 packet_start_compression(compression_level); 447 } 448 } 449 } 450 451 #define USE_PIPES 1 452 /* 453 * This is called to fork and execute a command when we have no tty. This 454 * will call do_child from the child, and server_loop from the parent after 455 * setting up file descriptors and such. 456 */ 457 int 458 do_exec_no_pty(Session *s, const char *command) 459 { 460 pid_t pid; 461 462 #ifdef USE_PIPES 463 int pin[2], pout[2], perr[2]; 464 465 if (s == NULL) 466 fatal("do_exec_no_pty: no session"); 467 468 /* Allocate pipes for communicating with the program. */ 469 if (pipe(pin) < 0) { 470 error("%s: pipe in: %.100s", __func__, strerror(errno)); 471 return -1; 472 } 473 if (pipe(pout) < 0) { 474 error("%s: pipe out: %.100s", __func__, strerror(errno)); 475 close(pin[0]); 476 close(pin[1]); 477 return -1; 478 } 479 if (pipe(perr) < 0) { 480 error("%s: pipe err: %.100s", __func__, 481 strerror(errno)); 482 close(pin[0]); 483 close(pin[1]); 484 close(pout[0]); 485 close(pout[1]); 486 return -1; 487 } 488 #else 489 int inout[2], err[2]; 490 491 if (s == NULL) 492 fatal("do_exec_no_pty: no session"); 493 494 /* Uses socket pairs to communicate with the program. */ 495 if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) < 0) { 496 error("%s: socketpair #1: %.100s", __func__, strerror(errno)); 497 return -1; 498 } 499 if (socketpair(AF_UNIX, SOCK_STREAM, 0, err) < 0) { 500 error("%s: socketpair #2: %.100s", __func__, 501 strerror(errno)); 502 close(inout[0]); 503 close(inout[1]); 504 return -1; 505 } 506 #endif 507 508 session_proctitle(s); 509 510 /* Fork the child. */ 511 switch ((pid = fork())) { 512 case -1: 513 error("%s: fork: %.100s", __func__, strerror(errno)); 514 #ifdef USE_PIPES 515 close(pin[0]); 516 close(pin[1]); 517 close(pout[0]); 518 close(pout[1]); 519 close(perr[0]); 520 close(perr[1]); 521 #else 522 close(inout[0]); 523 close(inout[1]); 524 close(err[0]); 525 close(err[1]); 526 #endif 527 return -1; 528 case 0: 529 is_child = 1; 530 531 /* Child. Reinitialize the log since the pid has changed. */ 532 log_init(__progname, options.log_level, 533 options.log_facility, log_stderr); 534 535 /* 536 * Create a new session and process group since the 4.4BSD 537 * setlogin() affects the entire process group. 538 */ 539 if (setsid() < 0) 540 error("setsid failed: %.100s", strerror(errno)); 541 542 #ifdef USE_PIPES 543 /* 544 * Redirect stdin. We close the parent side of the socket 545 * pair, and make the child side the standard input. 546 */ 547 close(pin[1]); 548 if (dup2(pin[0], 0) < 0) 549 perror("dup2 stdin"); 550 close(pin[0]); 551 552 /* Redirect stdout. */ 553 close(pout[0]); 554 if (dup2(pout[1], 1) < 0) 555 perror("dup2 stdout"); 556 close(pout[1]); 557 558 /* Redirect stderr. */ 559 close(perr[0]); 560 if (dup2(perr[1], 2) < 0) 561 perror("dup2 stderr"); 562 close(perr[1]); 563 #else 564 /* 565 * Redirect stdin, stdout, and stderr. Stdin and stdout will 566 * use the same socket, as some programs (particularly rdist) 567 * seem to depend on it. 568 */ 569 close(inout[1]); 570 close(err[1]); 571 if (dup2(inout[0], 0) < 0) /* stdin */ 572 perror("dup2 stdin"); 573 if (dup2(inout[0], 1) < 0) /* stdout (same as stdin) */ 574 perror("dup2 stdout"); 575 close(inout[0]); 576 if (dup2(err[0], 2) < 0) /* stderr */ 577 perror("dup2 stderr"); 578 close(err[0]); 579 #endif 580 581 582 #ifdef _UNICOS 583 cray_init_job(s->pw); /* set up cray jid and tmpdir */ 584 #endif 585 586 /* Do processing for the child (exec command etc). */ 587 do_child(s, command); 588 /* NOTREACHED */ 589 default: 590 break; 591 } 592 593 #ifdef _UNICOS 594 signal(WJSIGNAL, cray_job_termination_handler); 595 #endif /* _UNICOS */ 596 #ifdef HAVE_CYGWIN 597 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); 598 #endif 599 600 s->pid = pid; 601 /* Set interactive/non-interactive mode. */ 602 packet_set_interactive(s->display != NULL, 603 options.ip_qos_interactive, options.ip_qos_bulk); 604 605 /* 606 * Clear loginmsg, since it's the child's responsibility to display 607 * it to the user, otherwise multiple sessions may accumulate 608 * multiple copies of the login messages. 609 */ 610 buffer_clear(&loginmsg); 611 612 #ifdef USE_PIPES 613 /* We are the parent. Close the child sides of the pipes. */ 614 close(pin[0]); 615 close(pout[1]); 616 close(perr[1]); 617 618 if (compat20) { 619 session_set_fds(s, pin[1], pout[0], perr[0], 620 s->is_subsystem, 0); 621 } else { 622 /* Enter the interactive session. */ 623 server_loop(pid, pin[1], pout[0], perr[0]); 624 /* server_loop has closed pin[1], pout[0], and perr[0]. */ 625 } 626 #else 627 /* We are the parent. Close the child sides of the socket pairs. */ 628 close(inout[0]); 629 close(err[0]); 630 631 /* 632 * Enter the interactive session. Note: server_loop must be able to 633 * handle the case that fdin and fdout are the same. 634 */ 635 if (compat20) { 636 session_set_fds(s, inout[1], inout[1], err[1], 637 s->is_subsystem, 0); 638 } else { 639 server_loop(pid, inout[1], inout[1], err[1]); 640 /* server_loop has closed inout[1] and err[1]. */ 641 } 642 #endif 643 return 0; 644 } 645 646 /* 647 * This is called to fork and execute a command when we have a tty. This 648 * will call do_child from the child, and server_loop from the parent after 649 * setting up file descriptors, controlling tty, updating wtmp, utmp, 650 * lastlog, and other such operations. 651 */ 652 int 653 do_exec_pty(Session *s, const char *command) 654 { 655 int fdout, ptyfd, ttyfd, ptymaster; 656 pid_t pid; 657 658 if (s == NULL) 659 fatal("do_exec_pty: no session"); 660 ptyfd = s->ptyfd; 661 ttyfd = s->ttyfd; 662 663 /* 664 * Create another descriptor of the pty master side for use as the 665 * standard input. We could use the original descriptor, but this 666 * simplifies code in server_loop. The descriptor is bidirectional. 667 * Do this before forking (and cleanup in the child) so as to 668 * detect and gracefully fail out-of-fd conditions. 669 */ 670 if ((fdout = dup(ptyfd)) < 0) { 671 error("%s: dup #1: %s", __func__, strerror(errno)); 672 close(ttyfd); 673 close(ptyfd); 674 return -1; 675 } 676 /* we keep a reference to the pty master */ 677 if ((ptymaster = dup(ptyfd)) < 0) { 678 error("%s: dup #2: %s", __func__, strerror(errno)); 679 close(ttyfd); 680 close(ptyfd); 681 close(fdout); 682 return -1; 683 } 684 685 /* Fork the child. */ 686 switch ((pid = fork())) { 687 case -1: 688 error("%s: fork: %.100s", __func__, strerror(errno)); 689 close(fdout); 690 close(ptymaster); 691 close(ttyfd); 692 close(ptyfd); 693 return -1; 694 case 0: 695 is_child = 1; 696 697 close(fdout); 698 close(ptymaster); 699 700 /* Child. Reinitialize the log because the pid has changed. */ 701 log_init(__progname, options.log_level, 702 options.log_facility, log_stderr); 703 /* Close the master side of the pseudo tty. */ 704 close(ptyfd); 705 706 /* Make the pseudo tty our controlling tty. */ 707 pty_make_controlling_tty(&ttyfd, s->tty); 708 709 /* Redirect stdin/stdout/stderr from the pseudo tty. */ 710 if (dup2(ttyfd, 0) < 0) 711 error("dup2 stdin: %s", strerror(errno)); 712 if (dup2(ttyfd, 1) < 0) 713 error("dup2 stdout: %s", strerror(errno)); 714 if (dup2(ttyfd, 2) < 0) 715 error("dup2 stderr: %s", strerror(errno)); 716 717 /* Close the extra descriptor for the pseudo tty. */ 718 close(ttyfd); 719 720 /* record login, etc. similar to login(1) */ 721 #ifndef HAVE_OSF_SIA 722 if (!(options.use_login && command == NULL)) { 723 #ifdef _UNICOS 724 cray_init_job(s->pw); /* set up cray jid and tmpdir */ 725 #endif /* _UNICOS */ 726 do_login(s, command); 727 } 728 # ifdef LOGIN_NEEDS_UTMPX 729 else 730 do_pre_login(s); 731 # endif 732 #endif 733 /* 734 * Do common processing for the child, such as execing 735 * the command. 736 */ 737 do_child(s, command); 738 /* NOTREACHED */ 739 default: 740 break; 741 } 742 743 #ifdef _UNICOS 744 signal(WJSIGNAL, cray_job_termination_handler); 745 #endif /* _UNICOS */ 746 #ifdef HAVE_CYGWIN 747 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); 748 #endif 749 750 s->pid = pid; 751 752 /* Parent. Close the slave side of the pseudo tty. */ 753 close(ttyfd); 754 755 /* Enter interactive session. */ 756 s->ptymaster = ptymaster; 757 packet_set_interactive(1, 758 options.ip_qos_interactive, options.ip_qos_bulk); 759 if (compat20) { 760 session_set_fds(s, ptyfd, fdout, -1, 1, 1); 761 } else { 762 server_loop(pid, ptyfd, fdout, -1); 763 /* server_loop _has_ closed ptyfd and fdout. */ 764 } 765 return 0; 766 } 767 768 #ifdef LOGIN_NEEDS_UTMPX 769 static void 770 do_pre_login(Session *s) 771 { 772 struct ssh *ssh = active_state; /* XXX */ 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 session_get_remote_name_or_ip(ssh, 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 struct ssh *ssh = active_state; /* XXX */ 805 int ret; 806 const char *forced = NULL, *tty = NULL; 807 char session_type[1024]; 808 809 if (options.adm_forced_command) { 810 original_command = command; 811 command = options.adm_forced_command; 812 forced = "(config)"; 813 } else if (forced_command) { 814 original_command = command; 815 command = forced_command; 816 forced = "(key-option)"; 817 } 818 if (forced != NULL) { 819 if (IS_INTERNAL_SFTP(command)) { 820 s->is_subsystem = s->is_subsystem ? 821 SUBSYSTEM_INT_SFTP : SUBSYSTEM_INT_SFTP_ERROR; 822 } else if (s->is_subsystem) 823 s->is_subsystem = SUBSYSTEM_EXT; 824 snprintf(session_type, sizeof(session_type), 825 "forced-command %s '%.900s'", forced, command); 826 } else if (s->is_subsystem) { 827 snprintf(session_type, sizeof(session_type), 828 "subsystem '%.900s'", s->subsys); 829 } else if (command == NULL) { 830 snprintf(session_type, sizeof(session_type), "shell"); 831 } else { 832 /* NB. we don't log unforced commands to preserve privacy */ 833 snprintf(session_type, sizeof(session_type), "command"); 834 } 835 836 if (s->ttyfd != -1) { 837 tty = s->tty; 838 if (strncmp(tty, "/dev/", 5) == 0) 839 tty += 5; 840 } 841 842 verbose("Starting session: %s%s%s for %s from %.200s port %d id %d", 843 session_type, 844 tty == NULL ? "" : " on ", 845 tty == NULL ? "" : tty, 846 s->pw->pw_name, 847 ssh_remote_ipaddr(ssh), 848 ssh_remote_port(ssh), 849 s->self); 850 851 #ifdef SSH_AUDIT_EVENTS 852 if (command != NULL) 853 PRIVSEP(audit_run_command(command)); 854 else if (s->ttyfd == -1) { 855 char *shell = s->pw->pw_shell; 856 857 if (shell[0] == '\0') /* empty shell means /bin/sh */ 858 shell =_PATH_BSHELL; 859 PRIVSEP(audit_run_command(shell)); 860 } 861 #endif 862 if (s->ttyfd != -1) 863 ret = do_exec_pty(s, command); 864 else 865 ret = do_exec_no_pty(s, command); 866 867 original_command = NULL; 868 869 /* 870 * Clear loginmsg: it's the child's responsibility to display 871 * it to the user, otherwise multiple sessions may accumulate 872 * multiple copies of the login messages. 873 */ 874 buffer_clear(&loginmsg); 875 876 return ret; 877 } 878 879 /* administrative, login(1)-like work */ 880 void 881 do_login(Session *s, const char *command) 882 { 883 struct ssh *ssh = active_state; /* XXX */ 884 socklen_t fromlen; 885 struct sockaddr_storage from; 886 struct passwd * pw = s->pw; 887 pid_t pid = getpid(); 888 889 /* 890 * Get IP address of client. If the connection is not a socket, let 891 * the address be 0.0.0.0. 892 */ 893 memset(&from, 0, sizeof(from)); 894 fromlen = sizeof(from); 895 if (packet_connection_is_on_socket()) { 896 if (getpeername(packet_get_connection_in(), 897 (struct sockaddr *)&from, &fromlen) < 0) { 898 debug("getpeername: %.100s", strerror(errno)); 899 cleanup_exit(255); 900 } 901 } 902 903 /* Record that there was a login on that tty from the remote host. */ 904 if (!use_privsep) 905 record_login(pid, s->tty, pw->pw_name, pw->pw_uid, 906 session_get_remote_name_or_ip(ssh, utmp_len, 907 options.use_dns), 908 (struct sockaddr *)&from, fromlen); 909 910 #ifdef USE_PAM 911 /* 912 * If password change is needed, do it now. 913 * This needs to occur before the ~/.hushlogin check. 914 */ 915 if (options.use_pam && !use_privsep && s->authctxt->force_pwchange) { 916 display_loginmsg(); 917 do_pam_chauthtok(); 918 s->authctxt->force_pwchange = 0; 919 /* XXX - signal [net] parent to enable forwardings */ 920 } 921 #endif 922 923 if (check_quietlogin(s, command)) 924 return; 925 926 display_loginmsg(); 927 928 do_motd(); 929 } 930 931 /* 932 * Display the message of the day. 933 */ 934 void 935 do_motd(void) 936 { 937 FILE *f; 938 char buf[256]; 939 940 if (options.print_motd) { 941 #ifdef HAVE_LOGIN_CAP 942 f = fopen(login_getcapstr(lc, "welcome", "/etc/motd", 943 "/etc/motd"), "r"); 944 #else 945 f = fopen("/etc/motd", "r"); 946 #endif 947 if (f) { 948 while (fgets(buf, sizeof(buf), f)) 949 fputs(buf, stdout); 950 fclose(f); 951 } 952 } 953 } 954 955 956 /* 957 * Check for quiet login, either .hushlogin or command given. 958 */ 959 int 960 check_quietlogin(Session *s, const char *command) 961 { 962 char buf[256]; 963 struct passwd *pw = s->pw; 964 struct stat st; 965 966 /* Return 1 if .hushlogin exists or a command given. */ 967 if (command != NULL) 968 return 1; 969 snprintf(buf, sizeof(buf), "%.200s/.hushlogin", pw->pw_dir); 970 #ifdef HAVE_LOGIN_CAP 971 if (login_getcapbool(lc, "hushlogin", 0) || stat(buf, &st) >= 0) 972 return 1; 973 #else 974 if (stat(buf, &st) >= 0) 975 return 1; 976 #endif 977 return 0; 978 } 979 980 /* 981 * Sets the value of the given variable in the environment. If the variable 982 * already exists, its value is overridden. 983 */ 984 void 985 child_set_env(char ***envp, u_int *envsizep, const char *name, 986 const char *value) 987 { 988 char **env; 989 u_int envsize; 990 u_int i, namelen; 991 992 if (strchr(name, '=') != NULL) { 993 error("Invalid environment variable \"%.100s\"", name); 994 return; 995 } 996 997 /* 998 * If we're passed an uninitialized list, allocate a single null 999 * entry before continuing. 1000 */ 1001 if (*envp == NULL && *envsizep == 0) { 1002 *envp = xmalloc(sizeof(char *)); 1003 *envp[0] = NULL; 1004 *envsizep = 1; 1005 } 1006 1007 /* 1008 * Find the slot where the value should be stored. If the variable 1009 * already exists, we reuse the slot; otherwise we append a new slot 1010 * at the end of the array, expanding if necessary. 1011 */ 1012 env = *envp; 1013 namelen = strlen(name); 1014 for (i = 0; env[i]; i++) 1015 if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=') 1016 break; 1017 if (env[i]) { 1018 /* Reuse the slot. */ 1019 free(env[i]); 1020 } else { 1021 /* New variable. Expand if necessary. */ 1022 envsize = *envsizep; 1023 if (i >= envsize - 1) { 1024 if (envsize >= 1000) 1025 fatal("child_set_env: too many env vars"); 1026 envsize += 50; 1027 env = (*envp) = xreallocarray(env, envsize, sizeof(char *)); 1028 *envsizep = envsize; 1029 } 1030 /* Need to set the NULL pointer at end of array beyond the new slot. */ 1031 env[i + 1] = NULL; 1032 } 1033 1034 /* Allocate space and format the variable in the appropriate slot. */ 1035 env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1); 1036 snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value); 1037 } 1038 1039 /* 1040 * Reads environment variables from the given file and adds/overrides them 1041 * into the environment. If the file does not exist, this does nothing. 1042 * Otherwise, it must consist of empty lines, comments (line starts with '#') 1043 * and assignments of the form name=value. No other forms are allowed. 1044 */ 1045 static void 1046 read_environment_file(char ***env, u_int *envsize, 1047 const char *filename) 1048 { 1049 FILE *f; 1050 char buf[4096]; 1051 char *cp, *value; 1052 u_int lineno = 0; 1053 1054 f = fopen(filename, "r"); 1055 if (!f) 1056 return; 1057 1058 while (fgets(buf, sizeof(buf), f)) { 1059 if (++lineno > 1000) 1060 fatal("Too many lines in environment file %s", filename); 1061 for (cp = buf; *cp == ' ' || *cp == '\t'; cp++) 1062 ; 1063 if (!*cp || *cp == '#' || *cp == '\n') 1064 continue; 1065 1066 cp[strcspn(cp, "\n")] = '\0'; 1067 1068 value = strchr(cp, '='); 1069 if (value == NULL) { 1070 fprintf(stderr, "Bad line %u in %.100s\n", lineno, 1071 filename); 1072 continue; 1073 } 1074 /* 1075 * Replace the equals sign by nul, and advance value to 1076 * the value string. 1077 */ 1078 *value = '\0'; 1079 value++; 1080 child_set_env(env, envsize, cp, value); 1081 } 1082 fclose(f); 1083 } 1084 1085 #ifdef HAVE_ETC_DEFAULT_LOGIN 1086 /* 1087 * Return named variable from specified environment, or NULL if not present. 1088 */ 1089 static char * 1090 child_get_env(char **env, const char *name) 1091 { 1092 int i; 1093 size_t len; 1094 1095 len = strlen(name); 1096 for (i=0; env[i] != NULL; i++) 1097 if (strncmp(name, env[i], len) == 0 && env[i][len] == '=') 1098 return(env[i] + len + 1); 1099 return NULL; 1100 } 1101 1102 /* 1103 * Read /etc/default/login. 1104 * We pick up the PATH (or SUPATH for root) and UMASK. 1105 */ 1106 static void 1107 read_etc_default_login(char ***env, u_int *envsize, uid_t uid) 1108 { 1109 char **tmpenv = NULL, *var; 1110 u_int i, tmpenvsize = 0; 1111 u_long mask; 1112 1113 /* 1114 * We don't want to copy the whole file to the child's environment, 1115 * so we use a temporary environment and copy the variables we're 1116 * interested in. 1117 */ 1118 read_environment_file(&tmpenv, &tmpenvsize, "/etc/default/login"); 1119 1120 if (tmpenv == NULL) 1121 return; 1122 1123 if (uid == 0) 1124 var = child_get_env(tmpenv, "SUPATH"); 1125 else 1126 var = child_get_env(tmpenv, "PATH"); 1127 if (var != NULL) 1128 child_set_env(env, envsize, "PATH", var); 1129 1130 if ((var = child_get_env(tmpenv, "UMASK")) != NULL) 1131 if (sscanf(var, "%5lo", &mask) == 1) 1132 umask((mode_t)mask); 1133 1134 for (i = 0; tmpenv[i] != NULL; i++) 1135 free(tmpenv[i]); 1136 free(tmpenv); 1137 } 1138 #endif /* HAVE_ETC_DEFAULT_LOGIN */ 1139 1140 static void 1141 copy_environment(char **source, char ***env, u_int *envsize) 1142 { 1143 char *var_name, *var_val; 1144 int i; 1145 1146 if (source == NULL) 1147 return; 1148 1149 for(i = 0; source[i] != NULL; i++) { 1150 var_name = xstrdup(source[i]); 1151 if ((var_val = strstr(var_name, "=")) == NULL) { 1152 free(var_name); 1153 continue; 1154 } 1155 *var_val++ = '\0'; 1156 1157 debug3("Copy environment: %s=%s", var_name, var_val); 1158 child_set_env(env, envsize, var_name, var_val); 1159 1160 free(var_name); 1161 } 1162 } 1163 1164 static char ** 1165 do_setup_env(Session *s, const char *shell) 1166 { 1167 struct ssh *ssh = active_state; /* XXX */ 1168 char buf[256]; 1169 u_int i, envsize; 1170 char **env, *laddr; 1171 struct passwd *pw = s->pw; 1172 #if !defined (HAVE_LOGIN_CAP) && !defined (HAVE_CYGWIN) 1173 char *path = NULL; 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 #ifdef GSSAPI 1196 /* Allow any GSSAPI methods that we've used to alter 1197 * the childs environment as they see fit 1198 */ 1199 ssh_gssapi_do_child(&env, &envsize); 1200 #endif 1201 1202 if (!options.use_login) { 1203 /* Set basic environment. */ 1204 for (i = 0; i < s->num_env; i++) 1205 child_set_env(&env, &envsize, s->env[i].name, 1206 s->env[i].val); 1207 1208 child_set_env(&env, &envsize, "USER", pw->pw_name); 1209 child_set_env(&env, &envsize, "LOGNAME", pw->pw_name); 1210 #ifdef _AIX 1211 child_set_env(&env, &envsize, "LOGIN", pw->pw_name); 1212 #endif 1213 child_set_env(&env, &envsize, "HOME", pw->pw_dir); 1214 #ifdef HAVE_LOGIN_CAP 1215 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETPATH) < 0) 1216 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); 1217 else 1218 child_set_env(&env, &envsize, "PATH", getenv("PATH")); 1219 #else /* HAVE_LOGIN_CAP */ 1220 # ifndef HAVE_CYGWIN 1221 /* 1222 * There's no standard path on Windows. The path contains 1223 * important components pointing to the system directories, 1224 * needed for loading shared libraries. So the path better 1225 * remains intact here. 1226 */ 1227 # ifdef HAVE_ETC_DEFAULT_LOGIN 1228 read_etc_default_login(&env, &envsize, pw->pw_uid); 1229 path = child_get_env(env, "PATH"); 1230 # endif /* HAVE_ETC_DEFAULT_LOGIN */ 1231 if (path == NULL || *path == '\0') { 1232 child_set_env(&env, &envsize, "PATH", 1233 s->pw->pw_uid == 0 ? 1234 SUPERUSER_PATH : _PATH_STDPATH); 1235 } 1236 # endif /* HAVE_CYGWIN */ 1237 #endif /* HAVE_LOGIN_CAP */ 1238 1239 snprintf(buf, sizeof buf, "%.200s/%.50s", 1240 _PATH_MAILDIR, pw->pw_name); 1241 child_set_env(&env, &envsize, "MAIL", buf); 1242 1243 /* Normal systems set SHELL by default. */ 1244 child_set_env(&env, &envsize, "SHELL", shell); 1245 } 1246 if (getenv("TZ")) 1247 child_set_env(&env, &envsize, "TZ", getenv("TZ")); 1248 1249 /* Set custom environment options from RSA authentication. */ 1250 if (!options.use_login) { 1251 while (custom_environment) { 1252 struct envstring *ce = custom_environment; 1253 char *str = ce->s; 1254 1255 for (i = 0; str[i] != '=' && str[i]; i++) 1256 ; 1257 if (str[i] == '=') { 1258 str[i] = 0; 1259 child_set_env(&env, &envsize, str, str + i + 1); 1260 } 1261 custom_environment = ce->next; 1262 free(ce->s); 1263 free(ce); 1264 } 1265 } 1266 1267 /* SSH_CLIENT deprecated */ 1268 snprintf(buf, sizeof buf, "%.50s %d %d", 1269 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 1270 ssh_local_port(ssh)); 1271 child_set_env(&env, &envsize, "SSH_CLIENT", buf); 1272 1273 laddr = get_local_ipaddr(packet_get_connection_in()); 1274 snprintf(buf, sizeof buf, "%.50s %d %.50s %d", 1275 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 1276 laddr, ssh_local_port(ssh)); 1277 free(laddr); 1278 child_set_env(&env, &envsize, "SSH_CONNECTION", buf); 1279 1280 if (s->ttyfd != -1) 1281 child_set_env(&env, &envsize, "SSH_TTY", s->tty); 1282 if (s->term) 1283 child_set_env(&env, &envsize, "TERM", s->term); 1284 if (s->display) 1285 child_set_env(&env, &envsize, "DISPLAY", s->display); 1286 if (original_command) 1287 child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND", 1288 original_command); 1289 1290 #ifdef _UNICOS 1291 if (cray_tmpdir[0] != '\0') 1292 child_set_env(&env, &envsize, "TMPDIR", cray_tmpdir); 1293 #endif /* _UNICOS */ 1294 1295 /* 1296 * Since we clear KRB5CCNAME at startup, if it's set now then it 1297 * must have been set by a native authentication method (eg AIX or 1298 * SIA), so copy it to the child. 1299 */ 1300 { 1301 char *cp; 1302 1303 if ((cp = getenv("KRB5CCNAME")) != NULL) 1304 child_set_env(&env, &envsize, "KRB5CCNAME", cp); 1305 } 1306 1307 #ifdef _AIX 1308 { 1309 char *cp; 1310 1311 if ((cp = getenv("AUTHSTATE")) != NULL) 1312 child_set_env(&env, &envsize, "AUTHSTATE", cp); 1313 read_environment_file(&env, &envsize, "/etc/environment"); 1314 } 1315 #endif 1316 #ifdef KRB5 1317 if (s->authctxt->krb5_ccname) 1318 child_set_env(&env, &envsize, "KRB5CCNAME", 1319 s->authctxt->krb5_ccname); 1320 #endif 1321 #ifdef USE_PAM 1322 /* 1323 * Pull in any environment variables that may have 1324 * been set by PAM. 1325 */ 1326 if (options.use_pam && !options.use_login) { 1327 char **p; 1328 1329 p = fetch_pam_child_environment(); 1330 copy_environment(p, &env, &envsize); 1331 free_pam_environment(p); 1332 1333 p = fetch_pam_environment(); 1334 copy_environment(p, &env, &envsize); 1335 free_pam_environment(p); 1336 } 1337 #endif /* USE_PAM */ 1338 1339 if (auth_sock_name != NULL) 1340 child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME, 1341 auth_sock_name); 1342 1343 /* read $HOME/.ssh/environment. */ 1344 if (options.permit_user_env && !options.use_login) { 1345 snprintf(buf, sizeof buf, "%.200s/.ssh/environment", 1346 strcmp(pw->pw_dir, "/") ? pw->pw_dir : ""); 1347 read_environment_file(&env, &envsize, buf); 1348 } 1349 if (debug_flag) { 1350 /* dump the environment */ 1351 fprintf(stderr, "Environment:\n"); 1352 for (i = 0; env[i]; i++) 1353 fprintf(stderr, " %.200s\n", env[i]); 1354 } 1355 return env; 1356 } 1357 1358 /* 1359 * Run $HOME/.ssh/rc, /etc/ssh/sshrc, or xauth (whichever is found 1360 * first in this order). 1361 */ 1362 static void 1363 do_rc_files(Session *s, const char *shell) 1364 { 1365 FILE *f = NULL; 1366 char cmd[1024]; 1367 int do_xauth; 1368 struct stat st; 1369 1370 do_xauth = 1371 s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL; 1372 1373 /* ignore _PATH_SSH_USER_RC for subsystems and admin forced commands */ 1374 if (!s->is_subsystem && options.adm_forced_command == NULL && 1375 !no_user_rc && options.permit_user_rc && 1376 stat(_PATH_SSH_USER_RC, &st) >= 0) { 1377 snprintf(cmd, sizeof cmd, "%s -c '%s %s'", 1378 shell, _PATH_BSHELL, _PATH_SSH_USER_RC); 1379 if (debug_flag) 1380 fprintf(stderr, "Running %s\n", cmd); 1381 f = popen(cmd, "w"); 1382 if (f) { 1383 if (do_xauth) 1384 fprintf(f, "%s %s\n", s->auth_proto, 1385 s->auth_data); 1386 pclose(f); 1387 } else 1388 fprintf(stderr, "Could not run %s\n", 1389 _PATH_SSH_USER_RC); 1390 } else if (stat(_PATH_SSH_SYSTEM_RC, &st) >= 0) { 1391 if (debug_flag) 1392 fprintf(stderr, "Running %s %s\n", _PATH_BSHELL, 1393 _PATH_SSH_SYSTEM_RC); 1394 f = popen(_PATH_BSHELL " " _PATH_SSH_SYSTEM_RC, "w"); 1395 if (f) { 1396 if (do_xauth) 1397 fprintf(f, "%s %s\n", s->auth_proto, 1398 s->auth_data); 1399 pclose(f); 1400 } else 1401 fprintf(stderr, "Could not run %s\n", 1402 _PATH_SSH_SYSTEM_RC); 1403 } else if (do_xauth && options.xauth_location != NULL) { 1404 /* Add authority data to .Xauthority if appropriate. */ 1405 if (debug_flag) { 1406 fprintf(stderr, 1407 "Running %.500s remove %.100s\n", 1408 options.xauth_location, s->auth_display); 1409 fprintf(stderr, 1410 "%.500s add %.100s %.100s %.100s\n", 1411 options.xauth_location, s->auth_display, 1412 s->auth_proto, s->auth_data); 1413 } 1414 snprintf(cmd, sizeof cmd, "%s -q -", 1415 options.xauth_location); 1416 f = popen(cmd, "w"); 1417 if (f) { 1418 fprintf(f, "remove %s\n", 1419 s->auth_display); 1420 fprintf(f, "add %s %s %s\n", 1421 s->auth_display, s->auth_proto, 1422 s->auth_data); 1423 pclose(f); 1424 } else { 1425 fprintf(stderr, "Could not run %s\n", 1426 cmd); 1427 } 1428 } 1429 } 1430 1431 static void 1432 do_nologin(struct passwd *pw) 1433 { 1434 FILE *f = NULL; 1435 char buf[1024], *def_nl = _PATH_NOLOGIN; 1436 const char *nl; 1437 struct stat sb; 1438 1439 #ifdef HAVE_LOGIN_CAP 1440 if (login_getcapbool(lc, "ignorenologin", 0) || pw->pw_uid == 0) 1441 return; 1442 nl = login_getcapstr(lc, "nologin", def_nl, def_nl); 1443 #else 1444 if (pw->pw_uid == 0) 1445 return; 1446 nl = def_nl; 1447 #endif 1448 if (stat(nl, &sb) == -1) { 1449 if (nl != def_nl) 1450 free(__DECONST(char *, nl)); /* __DECONST() safe */ 1451 return; 1452 } 1453 1454 /* /etc/nologin exists. Print its contents if we can and exit. */ 1455 logit("User %.100s not allowed because %s exists", pw->pw_name, nl); 1456 if ((f = fopen(nl, "r")) != NULL) { 1457 while (fgets(buf, sizeof(buf), f)) 1458 fputs(buf, stderr); 1459 fclose(f); 1460 } 1461 exit(254); 1462 } 1463 1464 /* 1465 * Chroot into a directory after checking it for safety: all path components 1466 * must be root-owned directories with strict permissions. 1467 */ 1468 static void 1469 safely_chroot(const char *path, uid_t uid) 1470 { 1471 const char *cp; 1472 char component[PATH_MAX]; 1473 struct stat st; 1474 1475 if (*path != '/') 1476 fatal("chroot path does not begin at root"); 1477 if (strlen(path) >= sizeof(component)) 1478 fatal("chroot path too long"); 1479 1480 /* 1481 * Descend the path, checking that each component is a 1482 * root-owned directory with strict permissions. 1483 */ 1484 for (cp = path; cp != NULL;) { 1485 if ((cp = strchr(cp, '/')) == NULL) 1486 strlcpy(component, path, sizeof(component)); 1487 else { 1488 cp++; 1489 memcpy(component, path, cp - path); 1490 component[cp - path] = '\0'; 1491 } 1492 1493 debug3("%s: checking '%s'", __func__, component); 1494 1495 if (stat(component, &st) != 0) 1496 fatal("%s: stat(\"%s\"): %s", __func__, 1497 component, strerror(errno)); 1498 if (st.st_uid != 0 || (st.st_mode & 022) != 0) 1499 fatal("bad ownership or modes for chroot " 1500 "directory %s\"%s\"", 1501 cp == NULL ? "" : "component ", component); 1502 if (!S_ISDIR(st.st_mode)) 1503 fatal("chroot path %s\"%s\" is not a directory", 1504 cp == NULL ? "" : "component ", component); 1505 1506 } 1507 1508 if (chdir(path) == -1) 1509 fatal("Unable to chdir to chroot path \"%s\": " 1510 "%s", path, strerror(errno)); 1511 if (chroot(path) == -1) 1512 fatal("chroot(\"%s\"): %s", path, strerror(errno)); 1513 if (chdir("/") == -1) 1514 fatal("%s: chdir(/) after chroot: %s", 1515 __func__, strerror(errno)); 1516 verbose("Changed root directory to \"%s\"", path); 1517 } 1518 1519 /* Set login name, uid, gid, and groups. */ 1520 void 1521 do_setusercontext(struct passwd *pw) 1522 { 1523 char *chroot_path, *tmp; 1524 1525 platform_setusercontext(pw); 1526 1527 if (platform_privileged_uidswap()) { 1528 #ifdef HAVE_LOGIN_CAP 1529 if (setusercontext(lc, pw, pw->pw_uid, 1530 (LOGIN_SETALL & ~(LOGIN_SETPATH|LOGIN_SETUSER))) < 0) { 1531 perror("unable to set user context"); 1532 exit(1); 1533 } 1534 #else 1535 if (setlogin(pw->pw_name) < 0) 1536 error("setlogin failed: %s", strerror(errno)); 1537 if (setgid(pw->pw_gid) < 0) { 1538 perror("setgid"); 1539 exit(1); 1540 } 1541 /* Initialize the group list. */ 1542 if (initgroups(pw->pw_name, pw->pw_gid) < 0) { 1543 perror("initgroups"); 1544 exit(1); 1545 } 1546 endgrent(); 1547 #endif 1548 1549 platform_setusercontext_post_groups(pw); 1550 1551 if (!in_chroot && options.chroot_directory != NULL && 1552 strcasecmp(options.chroot_directory, "none") != 0) { 1553 tmp = tilde_expand_filename(options.chroot_directory, 1554 pw->pw_uid); 1555 chroot_path = percent_expand(tmp, "h", pw->pw_dir, 1556 "u", pw->pw_name, (char *)NULL); 1557 safely_chroot(chroot_path, pw->pw_uid); 1558 free(tmp); 1559 free(chroot_path); 1560 /* Make sure we don't attempt to chroot again */ 1561 free(options.chroot_directory); 1562 options.chroot_directory = NULL; 1563 in_chroot = 1; 1564 } 1565 1566 #ifdef HAVE_LOGIN_CAP 1567 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUSER) < 0) { 1568 perror("unable to set user context (setuser)"); 1569 exit(1); 1570 } 1571 /* 1572 * FreeBSD's setusercontext() will not apply the user's 1573 * own umask setting unless running with the user's UID. 1574 */ 1575 (void) setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUMASK); 1576 #else 1577 # ifdef USE_LIBIAF 1578 /* 1579 * In a chroot environment, the set_id() will always fail; 1580 * typically because of the lack of necessary authentication 1581 * services and runtime such as ./usr/lib/libiaf.so, 1582 * ./usr/lib/libpam.so.1, and ./etc/passwd We skip it in the 1583 * internal sftp chroot case. We'll lose auditing and ACLs but 1584 * permanently_set_uid will take care of the rest. 1585 */ 1586 if (!in_chroot && set_id(pw->pw_name) != 0) 1587 fatal("set_id(%s) Failed", pw->pw_name); 1588 # endif /* USE_LIBIAF */ 1589 /* Permanently switch to the desired uid. */ 1590 permanently_set_uid(pw); 1591 #endif 1592 } else if (options.chroot_directory != NULL && 1593 strcasecmp(options.chroot_directory, "none") != 0) { 1594 fatal("server lacks privileges to chroot to ChrootDirectory"); 1595 } 1596 1597 if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) 1598 fatal("Failed to set uids to %u.", (u_int) pw->pw_uid); 1599 } 1600 1601 static void 1602 do_pwchange(Session *s) 1603 { 1604 fflush(NULL); 1605 fprintf(stderr, "WARNING: Your password has expired.\n"); 1606 if (s->ttyfd != -1) { 1607 fprintf(stderr, 1608 "You must change your password now and login again!\n"); 1609 #ifdef WITH_SELINUX 1610 setexeccon(NULL); 1611 #endif 1612 #ifdef PASSWD_NEEDS_USERNAME 1613 execl(_PATH_PASSWD_PROG, "passwd", s->pw->pw_name, 1614 (char *)NULL); 1615 #else 1616 execl(_PATH_PASSWD_PROG, "passwd", (char *)NULL); 1617 #endif 1618 perror("passwd"); 1619 } else { 1620 fprintf(stderr, 1621 "Password change required but no TTY available.\n"); 1622 } 1623 exit(1); 1624 } 1625 1626 static void 1627 launch_login(struct passwd *pw, const char *hostname) 1628 { 1629 /* Launch login(1). */ 1630 1631 execl(LOGIN_PROGRAM, "login", "-h", hostname, 1632 #ifdef xxxLOGIN_NEEDS_TERM 1633 (s->term ? s->term : "unknown"), 1634 #endif /* LOGIN_NEEDS_TERM */ 1635 #ifdef LOGIN_NO_ENDOPT 1636 "-p", "-f", pw->pw_name, (char *)NULL); 1637 #else 1638 "-p", "-f", "--", pw->pw_name, (char *)NULL); 1639 #endif 1640 1641 /* Login couldn't be executed, die. */ 1642 1643 perror("login"); 1644 exit(1); 1645 } 1646 1647 static void 1648 child_close_fds(void) 1649 { 1650 extern int auth_sock; 1651 1652 if (auth_sock != -1) { 1653 close(auth_sock); 1654 auth_sock = -1; 1655 } 1656 1657 if (packet_get_connection_in() == packet_get_connection_out()) 1658 close(packet_get_connection_in()); 1659 else { 1660 close(packet_get_connection_in()); 1661 close(packet_get_connection_out()); 1662 } 1663 /* 1664 * Close all descriptors related to channels. They will still remain 1665 * open in the parent. 1666 */ 1667 /* XXX better use close-on-exec? -markus */ 1668 channel_close_all(); 1669 1670 /* 1671 * Close any extra file descriptors. Note that there may still be 1672 * descriptors left by system functions. They will be closed later. 1673 */ 1674 endpwent(); 1675 1676 /* 1677 * Close any extra open file descriptors so that we don't have them 1678 * hanging around in clients. Note that we want to do this after 1679 * initgroups, because at least on Solaris 2.3 it leaves file 1680 * descriptors open. 1681 */ 1682 closefrom(STDERR_FILENO + 1); 1683 } 1684 1685 /* 1686 * Performs common processing for the child, such as setting up the 1687 * environment, closing extra file descriptors, setting the user and group 1688 * ids, and executing the command or shell. 1689 */ 1690 #define ARGV_MAX 10 1691 void 1692 do_child(Session *s, const char *command) 1693 { 1694 struct ssh *ssh = active_state; /* XXX */ 1695 extern char **environ; 1696 char **env; 1697 char *argv[ARGV_MAX]; 1698 const char *shell, *shell0, *hostname = NULL; 1699 struct passwd *pw = s->pw; 1700 int r = 0; 1701 1702 /* remove hostkey from the child's memory */ 1703 destroy_sensitive_data(); 1704 1705 /* Force a password change */ 1706 if (s->authctxt->force_pwchange) { 1707 do_setusercontext(pw); 1708 child_close_fds(); 1709 do_pwchange(s); 1710 exit(1); 1711 } 1712 1713 /* login(1) is only called if we execute the login shell */ 1714 if (options.use_login && command != NULL) 1715 options.use_login = 0; 1716 1717 #ifdef _UNICOS 1718 cray_setup(pw->pw_uid, pw->pw_name, command); 1719 #endif /* _UNICOS */ 1720 1721 /* 1722 * Login(1) does this as well, and it needs uid 0 for the "-h" 1723 * switch, so we let login(1) to this for us. 1724 */ 1725 if (!options.use_login) { 1726 #ifdef HAVE_OSF_SIA 1727 session_setup_sia(pw, s->ttyfd == -1 ? NULL : s->tty); 1728 if (!check_quietlogin(s, command)) 1729 do_motd(); 1730 #else /* HAVE_OSF_SIA */ 1731 /* When PAM is enabled we rely on it to do the nologin check */ 1732 if (!options.use_pam) 1733 do_nologin(pw); 1734 do_setusercontext(pw); 1735 /* 1736 * PAM session modules in do_setusercontext may have 1737 * generated messages, so if this in an interactive 1738 * login then display them too. 1739 */ 1740 if (!check_quietlogin(s, command)) 1741 display_loginmsg(); 1742 #endif /* HAVE_OSF_SIA */ 1743 } 1744 1745 #ifdef USE_PAM 1746 if (options.use_pam && !options.use_login && !is_pam_session_open()) { 1747 debug3("PAM session not opened, exiting"); 1748 display_loginmsg(); 1749 exit(254); 1750 } 1751 #endif 1752 1753 /* 1754 * Get the shell from the password data. An empty shell field is 1755 * legal, and means /bin/sh. 1756 */ 1757 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; 1758 1759 /* 1760 * Make sure $SHELL points to the shell from the password file, 1761 * even if shell is overridden from login.conf 1762 */ 1763 env = do_setup_env(s, shell); 1764 1765 #ifdef HAVE_LOGIN_CAP 1766 shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell); 1767 #endif 1768 1769 /* we have to stash the hostname before we close our socket. */ 1770 if (options.use_login) 1771 hostname = session_get_remote_name_or_ip(ssh, utmp_len, 1772 options.use_dns); 1773 /* 1774 * Close the connection descriptors; note that this is the child, and 1775 * the server will still have the socket open, and it is important 1776 * that we do not shutdown it. Note that the descriptors cannot be 1777 * closed before building the environment, as we call 1778 * ssh_remote_ipaddr there. 1779 */ 1780 child_close_fds(); 1781 1782 /* 1783 * Must take new environment into use so that .ssh/rc, 1784 * /etc/ssh/sshrc and xauth are run in the proper environment. 1785 */ 1786 environ = env; 1787 1788 #if defined(KRB5) && defined(USE_AFS) 1789 /* 1790 * At this point, we check to see if AFS is active and if we have 1791 * a valid Kerberos 5 TGT. If so, it seems like a good idea to see 1792 * if we can (and need to) extend the ticket into an AFS token. If 1793 * we don't do this, we run into potential problems if the user's 1794 * home directory is in AFS and it's not world-readable. 1795 */ 1796 1797 if (options.kerberos_get_afs_token && k_hasafs() && 1798 (s->authctxt->krb5_ctx != NULL)) { 1799 char cell[64]; 1800 1801 debug("Getting AFS token"); 1802 1803 k_setpag(); 1804 1805 if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0) 1806 krb5_afslog(s->authctxt->krb5_ctx, 1807 s->authctxt->krb5_fwd_ccache, cell, NULL); 1808 1809 krb5_afslog_home(s->authctxt->krb5_ctx, 1810 s->authctxt->krb5_fwd_ccache, NULL, NULL, pw->pw_dir); 1811 } 1812 #endif 1813 1814 /* Change current directory to the user's home directory. */ 1815 if (chdir(pw->pw_dir) < 0) { 1816 /* Suppress missing homedir warning for chroot case */ 1817 #ifdef HAVE_LOGIN_CAP 1818 r = login_getcapbool(lc, "requirehome", 0); 1819 #endif 1820 if (r || !in_chroot) { 1821 fprintf(stderr, "Could not chdir to home " 1822 "directory %s: %s\n", pw->pw_dir, 1823 strerror(errno)); 1824 } 1825 if (r) 1826 exit(1); 1827 } 1828 1829 closefrom(STDERR_FILENO + 1); 1830 1831 if (!options.use_login) 1832 do_rc_files(s, shell); 1833 1834 /* restore SIGPIPE for child */ 1835 signal(SIGPIPE, SIG_DFL); 1836 1837 if (s->is_subsystem == SUBSYSTEM_INT_SFTP_ERROR) { 1838 printf("This service allows sftp connections only.\n"); 1839 fflush(NULL); 1840 exit(1); 1841 } else if (s->is_subsystem == SUBSYSTEM_INT_SFTP) { 1842 extern int optind, optreset; 1843 int i; 1844 char *p, *args; 1845 1846 setproctitle("%s@%s", s->pw->pw_name, INTERNAL_SFTP_NAME); 1847 args = xstrdup(command ? command : "sftp-server"); 1848 for (i = 0, (p = strtok(args, " ")); p; (p = strtok(NULL, " "))) 1849 if (i < ARGV_MAX - 1) 1850 argv[i++] = p; 1851 argv[i] = NULL; 1852 optind = optreset = 1; 1853 __progname = argv[0]; 1854 #ifdef WITH_SELINUX 1855 ssh_selinux_change_context("sftpd_t"); 1856 #endif 1857 exit(sftp_server_main(i, argv, s->pw)); 1858 } 1859 1860 fflush(NULL); 1861 1862 if (options.use_login) { 1863 launch_login(pw, hostname); 1864 /* NEVERREACHED */ 1865 } 1866 1867 /* Get the last component of the shell name. */ 1868 if ((shell0 = strrchr(shell, '/')) != NULL) 1869 shell0++; 1870 else 1871 shell0 = shell; 1872 1873 /* 1874 * If we have no command, execute the shell. In this case, the shell 1875 * name to be passed in argv[0] is preceded by '-' to indicate that 1876 * this is a login shell. 1877 */ 1878 if (!command) { 1879 char argv0[256]; 1880 1881 /* Start the shell. Set initial character to '-'. */ 1882 argv0[0] = '-'; 1883 1884 if (strlcpy(argv0 + 1, shell0, sizeof(argv0) - 1) 1885 >= sizeof(argv0) - 1) { 1886 errno = EINVAL; 1887 perror(shell); 1888 exit(1); 1889 } 1890 1891 /* Execute the shell. */ 1892 argv[0] = argv0; 1893 argv[1] = NULL; 1894 execve(shell, argv, env); 1895 1896 /* Executing the shell failed. */ 1897 perror(shell); 1898 exit(1); 1899 } 1900 /* 1901 * Execute the command using the user's shell. This uses the -c 1902 * option to execute the command. 1903 */ 1904 argv[0] = (char *) shell0; 1905 argv[1] = "-c"; 1906 argv[2] = (char *) command; 1907 argv[3] = NULL; 1908 execve(shell, argv, env); 1909 perror(shell); 1910 exit(1); 1911 } 1912 1913 void 1914 session_unused(int id) 1915 { 1916 debug3("%s: session id %d unused", __func__, id); 1917 if (id >= options.max_sessions || 1918 id >= sessions_nalloc) { 1919 fatal("%s: insane session id %d (max %d nalloc %d)", 1920 __func__, id, options.max_sessions, sessions_nalloc); 1921 } 1922 memset(&sessions[id], 0, sizeof(*sessions)); 1923 sessions[id].self = id; 1924 sessions[id].used = 0; 1925 sessions[id].chanid = -1; 1926 sessions[id].ptyfd = -1; 1927 sessions[id].ttyfd = -1; 1928 sessions[id].ptymaster = -1; 1929 sessions[id].x11_chanids = NULL; 1930 sessions[id].next_unused = sessions_first_unused; 1931 sessions_first_unused = id; 1932 } 1933 1934 Session * 1935 session_new(void) 1936 { 1937 Session *s, *tmp; 1938 1939 if (sessions_first_unused == -1) { 1940 if (sessions_nalloc >= options.max_sessions) 1941 return NULL; 1942 debug2("%s: allocate (allocated %d max %d)", 1943 __func__, sessions_nalloc, options.max_sessions); 1944 tmp = xreallocarray(sessions, sessions_nalloc + 1, 1945 sizeof(*sessions)); 1946 if (tmp == NULL) { 1947 error("%s: cannot allocate %d sessions", 1948 __func__, sessions_nalloc + 1); 1949 return NULL; 1950 } 1951 sessions = tmp; 1952 session_unused(sessions_nalloc++); 1953 } 1954 1955 if (sessions_first_unused >= sessions_nalloc || 1956 sessions_first_unused < 0) { 1957 fatal("%s: insane first_unused %d max %d nalloc %d", 1958 __func__, sessions_first_unused, options.max_sessions, 1959 sessions_nalloc); 1960 } 1961 1962 s = &sessions[sessions_first_unused]; 1963 if (s->used) { 1964 fatal("%s: session %d already used", 1965 __func__, sessions_first_unused); 1966 } 1967 sessions_first_unused = s->next_unused; 1968 s->used = 1; 1969 s->next_unused = -1; 1970 debug("session_new: session %d", s->self); 1971 1972 return s; 1973 } 1974 1975 static void 1976 session_dump(void) 1977 { 1978 int i; 1979 for (i = 0; i < sessions_nalloc; i++) { 1980 Session *s = &sessions[i]; 1981 1982 debug("dump: used %d next_unused %d session %d %p " 1983 "channel %d pid %ld", 1984 s->used, 1985 s->next_unused, 1986 s->self, 1987 s, 1988 s->chanid, 1989 (long)s->pid); 1990 } 1991 } 1992 1993 int 1994 session_open(Authctxt *authctxt, int chanid) 1995 { 1996 Session *s = session_new(); 1997 debug("session_open: channel %d", chanid); 1998 if (s == NULL) { 1999 error("no more sessions"); 2000 return 0; 2001 } 2002 s->authctxt = authctxt; 2003 s->pw = authctxt->pw; 2004 if (s->pw == NULL || !authctxt->valid) 2005 fatal("no user for session %d", s->self); 2006 debug("session_open: session %d: link with channel %d", s->self, chanid); 2007 s->chanid = chanid; 2008 return 1; 2009 } 2010 2011 Session * 2012 session_by_tty(char *tty) 2013 { 2014 int i; 2015 for (i = 0; i < sessions_nalloc; i++) { 2016 Session *s = &sessions[i]; 2017 if (s->used && s->ttyfd != -1 && strcmp(s->tty, tty) == 0) { 2018 debug("session_by_tty: session %d tty %s", i, tty); 2019 return s; 2020 } 2021 } 2022 debug("session_by_tty: unknown tty %.100s", tty); 2023 session_dump(); 2024 return NULL; 2025 } 2026 2027 static Session * 2028 session_by_channel(int id) 2029 { 2030 int i; 2031 for (i = 0; i < sessions_nalloc; i++) { 2032 Session *s = &sessions[i]; 2033 if (s->used && s->chanid == id) { 2034 debug("session_by_channel: session %d channel %d", 2035 i, id); 2036 return s; 2037 } 2038 } 2039 debug("session_by_channel: unknown channel %d", id); 2040 session_dump(); 2041 return NULL; 2042 } 2043 2044 static Session * 2045 session_by_x11_channel(int id) 2046 { 2047 int i, j; 2048 2049 for (i = 0; i < sessions_nalloc; i++) { 2050 Session *s = &sessions[i]; 2051 2052 if (s->x11_chanids == NULL || !s->used) 2053 continue; 2054 for (j = 0; s->x11_chanids[j] != -1; j++) { 2055 if (s->x11_chanids[j] == id) { 2056 debug("session_by_x11_channel: session %d " 2057 "channel %d", s->self, id); 2058 return s; 2059 } 2060 } 2061 } 2062 debug("session_by_x11_channel: unknown channel %d", id); 2063 session_dump(); 2064 return NULL; 2065 } 2066 2067 static Session * 2068 session_by_pid(pid_t pid) 2069 { 2070 int i; 2071 debug("session_by_pid: pid %ld", (long)pid); 2072 for (i = 0; i < sessions_nalloc; i++) { 2073 Session *s = &sessions[i]; 2074 if (s->used && s->pid == pid) 2075 return s; 2076 } 2077 error("session_by_pid: unknown pid %ld", (long)pid); 2078 session_dump(); 2079 return NULL; 2080 } 2081 2082 static int 2083 session_window_change_req(Session *s) 2084 { 2085 s->col = packet_get_int(); 2086 s->row = packet_get_int(); 2087 s->xpixel = packet_get_int(); 2088 s->ypixel = packet_get_int(); 2089 packet_check_eom(); 2090 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 2091 return 1; 2092 } 2093 2094 static int 2095 session_pty_req(Session *s) 2096 { 2097 u_int len; 2098 int n_bytes; 2099 2100 if (no_pty_flag || !options.permit_tty) { 2101 debug("Allocating a pty not permitted for this authentication."); 2102 return 0; 2103 } 2104 if (s->ttyfd != -1) { 2105 packet_disconnect("Protocol error: you already have a pty."); 2106 return 0; 2107 } 2108 2109 s->term = packet_get_string(&len); 2110 2111 if (compat20) { 2112 s->col = packet_get_int(); 2113 s->row = packet_get_int(); 2114 } else { 2115 s->row = packet_get_int(); 2116 s->col = packet_get_int(); 2117 } 2118 s->xpixel = packet_get_int(); 2119 s->ypixel = packet_get_int(); 2120 2121 if (strcmp(s->term, "") == 0) { 2122 free(s->term); 2123 s->term = NULL; 2124 } 2125 2126 /* Allocate a pty and open it. */ 2127 debug("Allocating pty."); 2128 if (!PRIVSEP(pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, 2129 sizeof(s->tty)))) { 2130 free(s->term); 2131 s->term = NULL; 2132 s->ptyfd = -1; 2133 s->ttyfd = -1; 2134 error("session_pty_req: session %d alloc failed", s->self); 2135 return 0; 2136 } 2137 debug("session_pty_req: session %d alloc %s", s->self, s->tty); 2138 2139 /* for SSH1 the tty modes length is not given */ 2140 if (!compat20) 2141 n_bytes = packet_remaining(); 2142 tty_parse_modes(s->ttyfd, &n_bytes); 2143 2144 if (!use_privsep) 2145 pty_setowner(s->pw, s->tty); 2146 2147 /* Set window size from the packet. */ 2148 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 2149 2150 packet_check_eom(); 2151 session_proctitle(s); 2152 return 1; 2153 } 2154 2155 static int 2156 session_subsystem_req(Session *s) 2157 { 2158 struct stat st; 2159 u_int len; 2160 int success = 0; 2161 char *prog, *cmd; 2162 u_int i; 2163 2164 s->subsys = packet_get_string(&len); 2165 packet_check_eom(); 2166 debug2("subsystem request for %.100s by user %s", s->subsys, 2167 s->pw->pw_name); 2168 2169 for (i = 0; i < options.num_subsystems; i++) { 2170 if (strcmp(s->subsys, options.subsystem_name[i]) == 0) { 2171 prog = options.subsystem_command[i]; 2172 cmd = options.subsystem_args[i]; 2173 if (strcmp(INTERNAL_SFTP_NAME, prog) == 0) { 2174 s->is_subsystem = SUBSYSTEM_INT_SFTP; 2175 debug("subsystem: %s", prog); 2176 } else { 2177 if (stat(prog, &st) < 0) 2178 debug("subsystem: cannot stat %s: %s", 2179 prog, strerror(errno)); 2180 s->is_subsystem = SUBSYSTEM_EXT; 2181 debug("subsystem: exec() %s", cmd); 2182 } 2183 success = do_exec(s, cmd) == 0; 2184 break; 2185 } 2186 } 2187 2188 if (!success) 2189 logit("subsystem request for %.100s by user %s failed, " 2190 "subsystem not found", s->subsys, s->pw->pw_name); 2191 2192 return success; 2193 } 2194 2195 static int 2196 session_x11_req(Session *s) 2197 { 2198 int success; 2199 2200 if (s->auth_proto != NULL || s->auth_data != NULL) { 2201 error("session_x11_req: session %d: " 2202 "x11 forwarding already active", s->self); 2203 return 0; 2204 } 2205 s->single_connection = packet_get_char(); 2206 s->auth_proto = packet_get_string(NULL); 2207 s->auth_data = packet_get_string(NULL); 2208 s->screen = packet_get_int(); 2209 packet_check_eom(); 2210 2211 if (xauth_valid_string(s->auth_proto) && 2212 xauth_valid_string(s->auth_data)) 2213 success = session_setup_x11fwd(s); 2214 else { 2215 success = 0; 2216 error("Invalid X11 forwarding data"); 2217 } 2218 if (!success) { 2219 free(s->auth_proto); 2220 free(s->auth_data); 2221 s->auth_proto = NULL; 2222 s->auth_data = NULL; 2223 } 2224 return success; 2225 } 2226 2227 static int 2228 session_shell_req(Session *s) 2229 { 2230 packet_check_eom(); 2231 return do_exec(s, NULL) == 0; 2232 } 2233 2234 static int 2235 session_exec_req(Session *s) 2236 { 2237 u_int len, success; 2238 2239 char *command = packet_get_string(&len); 2240 packet_check_eom(); 2241 success = do_exec(s, command) == 0; 2242 free(command); 2243 return success; 2244 } 2245 2246 static int 2247 session_break_req(Session *s) 2248 { 2249 2250 packet_get_int(); /* ignored */ 2251 packet_check_eom(); 2252 2253 if (s->ptymaster == -1 || tcsendbreak(s->ptymaster, 0) < 0) 2254 return 0; 2255 return 1; 2256 } 2257 2258 static int 2259 session_env_req(Session *s) 2260 { 2261 char *name, *val; 2262 u_int name_len, val_len, i; 2263 2264 name = packet_get_cstring(&name_len); 2265 val = packet_get_cstring(&val_len); 2266 packet_check_eom(); 2267 2268 /* Don't set too many environment variables */ 2269 if (s->num_env > 128) { 2270 debug2("Ignoring env request %s: too many env vars", name); 2271 goto fail; 2272 } 2273 2274 for (i = 0; i < options.num_accept_env; i++) { 2275 if (match_pattern(name, options.accept_env[i])) { 2276 debug2("Setting env %d: %s=%s", s->num_env, name, val); 2277 s->env = xreallocarray(s->env, s->num_env + 1, 2278 sizeof(*s->env)); 2279 s->env[s->num_env].name = name; 2280 s->env[s->num_env].val = val; 2281 s->num_env++; 2282 return (1); 2283 } 2284 } 2285 debug2("Ignoring env request %s: disallowed name", name); 2286 2287 fail: 2288 free(name); 2289 free(val); 2290 return (0); 2291 } 2292 2293 static int 2294 session_auth_agent_req(Session *s) 2295 { 2296 static int called = 0; 2297 packet_check_eom(); 2298 if (no_agent_forwarding_flag || !options.allow_agent_forwarding) { 2299 debug("session_auth_agent_req: no_agent_forwarding_flag"); 2300 return 0; 2301 } 2302 if (called) { 2303 return 0; 2304 } else { 2305 called = 1; 2306 return auth_input_request_forwarding(s->pw); 2307 } 2308 } 2309 2310 int 2311 session_input_channel_req(Channel *c, const char *rtype) 2312 { 2313 int success = 0; 2314 Session *s; 2315 2316 if ((s = session_by_channel(c->self)) == NULL) { 2317 logit("session_input_channel_req: no session %d req %.100s", 2318 c->self, rtype); 2319 return 0; 2320 } 2321 debug("session_input_channel_req: session %d req %s", s->self, rtype); 2322 2323 /* 2324 * a session is in LARVAL state until a shell, a command 2325 * or a subsystem is executed 2326 */ 2327 if (c->type == SSH_CHANNEL_LARVAL) { 2328 if (strcmp(rtype, "shell") == 0) { 2329 success = session_shell_req(s); 2330 } else if (strcmp(rtype, "exec") == 0) { 2331 success = session_exec_req(s); 2332 } else if (strcmp(rtype, "pty-req") == 0) { 2333 success = session_pty_req(s); 2334 } else if (strcmp(rtype, "x11-req") == 0) { 2335 success = session_x11_req(s); 2336 } else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) { 2337 success = session_auth_agent_req(s); 2338 } else if (strcmp(rtype, "subsystem") == 0) { 2339 success = session_subsystem_req(s); 2340 } else if (strcmp(rtype, "env") == 0) { 2341 success = session_env_req(s); 2342 } 2343 } 2344 if (strcmp(rtype, "window-change") == 0) { 2345 success = session_window_change_req(s); 2346 } else if (strcmp(rtype, "break") == 0) { 2347 success = session_break_req(s); 2348 } 2349 2350 return success; 2351 } 2352 2353 void 2354 session_set_fds(Session *s, int fdin, int fdout, int fderr, int ignore_fderr, 2355 int is_tty) 2356 { 2357 if (!compat20) 2358 fatal("session_set_fds: called for proto != 2.0"); 2359 /* 2360 * now that have a child and a pipe to the child, 2361 * we can activate our channel and register the fd's 2362 */ 2363 if (s->chanid == -1) 2364 fatal("no channel for session %d", s->self); 2365 channel_set_fds(s->chanid, 2366 fdout, fdin, fderr, 2367 ignore_fderr ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ, 2368 1, is_tty, CHAN_SES_WINDOW_DEFAULT); 2369 } 2370 2371 /* 2372 * Function to perform pty cleanup. Also called if we get aborted abnormally 2373 * (e.g., due to a dropped connection). 2374 */ 2375 void 2376 session_pty_cleanup2(Session *s) 2377 { 2378 if (s == NULL) { 2379 error("session_pty_cleanup: no session"); 2380 return; 2381 } 2382 if (s->ttyfd == -1) 2383 return; 2384 2385 debug("session_pty_cleanup: session %d release %s", s->self, s->tty); 2386 2387 /* Record that the user has logged out. */ 2388 if (s->pid != 0) 2389 record_logout(s->pid, s->tty, s->pw->pw_name); 2390 2391 /* Release the pseudo-tty. */ 2392 if (getuid() == 0) 2393 pty_release(s->tty); 2394 2395 /* 2396 * Close the server side of the socket pairs. We must do this after 2397 * the pty cleanup, so that another process doesn't get this pty 2398 * while we're still cleaning up. 2399 */ 2400 if (s->ptymaster != -1 && close(s->ptymaster) < 0) 2401 error("close(s->ptymaster/%d): %s", 2402 s->ptymaster, strerror(errno)); 2403 2404 /* unlink pty from session */ 2405 s->ttyfd = -1; 2406 } 2407 2408 void 2409 session_pty_cleanup(Session *s) 2410 { 2411 PRIVSEP(session_pty_cleanup2(s)); 2412 } 2413 2414 static char * 2415 sig2name(int sig) 2416 { 2417 #define SSH_SIG(x) if (sig == SIG ## x) return #x 2418 SSH_SIG(ABRT); 2419 SSH_SIG(ALRM); 2420 SSH_SIG(FPE); 2421 SSH_SIG(HUP); 2422 SSH_SIG(ILL); 2423 SSH_SIG(INT); 2424 SSH_SIG(KILL); 2425 SSH_SIG(PIPE); 2426 SSH_SIG(QUIT); 2427 SSH_SIG(SEGV); 2428 SSH_SIG(TERM); 2429 SSH_SIG(USR1); 2430 SSH_SIG(USR2); 2431 #undef SSH_SIG 2432 return "SIG@openssh.com"; 2433 } 2434 2435 static void 2436 session_close_x11(int id) 2437 { 2438 Channel *c; 2439 2440 if ((c = channel_by_id(id)) == NULL) { 2441 debug("session_close_x11: x11 channel %d missing", id); 2442 } else { 2443 /* Detach X11 listener */ 2444 debug("session_close_x11: detach x11 channel %d", id); 2445 channel_cancel_cleanup(id); 2446 if (c->ostate != CHAN_OUTPUT_CLOSED) 2447 chan_mark_dead(c); 2448 } 2449 } 2450 2451 static void 2452 session_close_single_x11(int id, void *arg) 2453 { 2454 Session *s; 2455 u_int i; 2456 2457 debug3("session_close_single_x11: channel %d", id); 2458 channel_cancel_cleanup(id); 2459 if ((s = session_by_x11_channel(id)) == NULL) 2460 fatal("session_close_single_x11: no x11 channel %d", id); 2461 for (i = 0; s->x11_chanids[i] != -1; i++) { 2462 debug("session_close_single_x11: session %d: " 2463 "closing channel %d", s->self, s->x11_chanids[i]); 2464 /* 2465 * The channel "id" is already closing, but make sure we 2466 * close all of its siblings. 2467 */ 2468 if (s->x11_chanids[i] != id) 2469 session_close_x11(s->x11_chanids[i]); 2470 } 2471 free(s->x11_chanids); 2472 s->x11_chanids = NULL; 2473 free(s->display); 2474 s->display = NULL; 2475 free(s->auth_proto); 2476 s->auth_proto = NULL; 2477 free(s->auth_data); 2478 s->auth_data = NULL; 2479 free(s->auth_display); 2480 s->auth_display = NULL; 2481 } 2482 2483 static void 2484 session_exit_message(Session *s, int status) 2485 { 2486 Channel *c; 2487 2488 if ((c = channel_lookup(s->chanid)) == NULL) 2489 fatal("session_exit_message: session %d: no channel %d", 2490 s->self, s->chanid); 2491 debug("session_exit_message: session %d channel %d pid %ld", 2492 s->self, s->chanid, (long)s->pid); 2493 2494 if (WIFEXITED(status)) { 2495 channel_request_start(s->chanid, "exit-status", 0); 2496 packet_put_int(WEXITSTATUS(status)); 2497 packet_send(); 2498 } else if (WIFSIGNALED(status)) { 2499 channel_request_start(s->chanid, "exit-signal", 0); 2500 packet_put_cstring(sig2name(WTERMSIG(status))); 2501 #ifdef WCOREDUMP 2502 packet_put_char(WCOREDUMP(status)? 1 : 0); 2503 #else /* WCOREDUMP */ 2504 packet_put_char(0); 2505 #endif /* WCOREDUMP */ 2506 packet_put_cstring(""); 2507 packet_put_cstring(""); 2508 packet_send(); 2509 } else { 2510 /* Some weird exit cause. Just exit. */ 2511 packet_disconnect("wait returned status %04x.", status); 2512 } 2513 2514 /* disconnect channel */ 2515 debug("session_exit_message: release channel %d", s->chanid); 2516 2517 /* 2518 * Adjust cleanup callback attachment to send close messages when 2519 * the channel gets EOF. The session will be then be closed 2520 * by session_close_by_channel when the childs close their fds. 2521 */ 2522 channel_register_cleanup(c->self, session_close_by_channel, 1); 2523 2524 /* 2525 * emulate a write failure with 'chan_write_failed', nobody will be 2526 * interested in data we write. 2527 * Note that we must not call 'chan_read_failed', since there could 2528 * be some more data waiting in the pipe. 2529 */ 2530 if (c->ostate != CHAN_OUTPUT_CLOSED) 2531 chan_write_failed(c); 2532 } 2533 2534 void 2535 session_close(Session *s) 2536 { 2537 struct ssh *ssh = active_state; /* XXX */ 2538 u_int i; 2539 2540 verbose("Close session: user %s from %.200s port %d id %d", 2541 s->pw->pw_name, 2542 ssh_remote_ipaddr(ssh), 2543 ssh_remote_port(ssh), 2544 s->self); 2545 2546 if (s->ttyfd != -1) 2547 session_pty_cleanup(s); 2548 free(s->term); 2549 free(s->display); 2550 free(s->x11_chanids); 2551 free(s->auth_display); 2552 free(s->auth_data); 2553 free(s->auth_proto); 2554 free(s->subsys); 2555 if (s->env != NULL) { 2556 for (i = 0; i < s->num_env; i++) { 2557 free(s->env[i].name); 2558 free(s->env[i].val); 2559 } 2560 free(s->env); 2561 } 2562 session_proctitle(s); 2563 session_unused(s->self); 2564 } 2565 2566 void 2567 session_close_by_pid(pid_t pid, int status) 2568 { 2569 Session *s = session_by_pid(pid); 2570 if (s == NULL) { 2571 debug("session_close_by_pid: no session for pid %ld", 2572 (long)pid); 2573 return; 2574 } 2575 if (s->chanid != -1) 2576 session_exit_message(s, status); 2577 if (s->ttyfd != -1) 2578 session_pty_cleanup(s); 2579 s->pid = 0; 2580 } 2581 2582 /* 2583 * this is called when a channel dies before 2584 * the session 'child' itself dies 2585 */ 2586 void 2587 session_close_by_channel(int id, void *arg) 2588 { 2589 Session *s = session_by_channel(id); 2590 u_int i; 2591 2592 if (s == NULL) { 2593 debug("session_close_by_channel: no session for id %d", id); 2594 return; 2595 } 2596 debug("session_close_by_channel: channel %d child %ld", 2597 id, (long)s->pid); 2598 if (s->pid != 0) { 2599 debug("session_close_by_channel: channel %d: has child", id); 2600 /* 2601 * delay detach of session, but release pty, since 2602 * the fd's to the child are already closed 2603 */ 2604 if (s->ttyfd != -1) 2605 session_pty_cleanup(s); 2606 return; 2607 } 2608 /* detach by removing callback */ 2609 channel_cancel_cleanup(s->chanid); 2610 2611 /* Close any X11 listeners associated with this session */ 2612 if (s->x11_chanids != NULL) { 2613 for (i = 0; s->x11_chanids[i] != -1; i++) { 2614 session_close_x11(s->x11_chanids[i]); 2615 s->x11_chanids[i] = -1; 2616 } 2617 } 2618 2619 s->chanid = -1; 2620 session_close(s); 2621 } 2622 2623 void 2624 session_destroy_all(void (*closefunc)(Session *)) 2625 { 2626 int i; 2627 for (i = 0; i < sessions_nalloc; i++) { 2628 Session *s = &sessions[i]; 2629 if (s->used) { 2630 if (closefunc != NULL) 2631 closefunc(s); 2632 else 2633 session_close(s); 2634 } 2635 } 2636 } 2637 2638 static char * 2639 session_tty_list(void) 2640 { 2641 static char buf[1024]; 2642 int i; 2643 char *cp; 2644 2645 buf[0] = '\0'; 2646 for (i = 0; i < sessions_nalloc; i++) { 2647 Session *s = &sessions[i]; 2648 if (s->used && s->ttyfd != -1) { 2649 2650 if (strncmp(s->tty, "/dev/", 5) != 0) { 2651 cp = strrchr(s->tty, '/'); 2652 cp = (cp == NULL) ? s->tty : cp + 1; 2653 } else 2654 cp = s->tty + 5; 2655 2656 if (buf[0] != '\0') 2657 strlcat(buf, ",", sizeof buf); 2658 strlcat(buf, cp, sizeof buf); 2659 } 2660 } 2661 if (buf[0] == '\0') 2662 strlcpy(buf, "notty", sizeof buf); 2663 return buf; 2664 } 2665 2666 void 2667 session_proctitle(Session *s) 2668 { 2669 if (s->pw == NULL) 2670 error("no user for session %d", s->self); 2671 else 2672 setproctitle("%s@%s", s->pw->pw_name, session_tty_list()); 2673 } 2674 2675 int 2676 session_setup_x11fwd(Session *s) 2677 { 2678 struct stat st; 2679 char display[512], auth_display[512]; 2680 char hostname[NI_MAXHOST]; 2681 u_int i; 2682 2683 if (no_x11_forwarding_flag) { 2684 packet_send_debug("X11 forwarding disabled in user configuration file."); 2685 return 0; 2686 } 2687 if (!options.x11_forwarding) { 2688 debug("X11 forwarding disabled in server configuration file."); 2689 return 0; 2690 } 2691 if (options.xauth_location == NULL || 2692 (stat(options.xauth_location, &st) == -1)) { 2693 packet_send_debug("No xauth program; cannot forward with spoofing."); 2694 return 0; 2695 } 2696 if (options.use_login) { 2697 packet_send_debug("X11 forwarding disabled; " 2698 "not compatible with UseLogin=yes."); 2699 return 0; 2700 } 2701 if (s->display != NULL) { 2702 debug("X11 display already set."); 2703 return 0; 2704 } 2705 if (x11_create_display_inet(options.x11_display_offset, 2706 options.x11_use_localhost, s->single_connection, 2707 &s->display_number, &s->x11_chanids) == -1) { 2708 debug("x11_create_display_inet failed."); 2709 return 0; 2710 } 2711 for (i = 0; s->x11_chanids[i] != -1; i++) { 2712 channel_register_cleanup(s->x11_chanids[i], 2713 session_close_single_x11, 0); 2714 } 2715 2716 /* Set up a suitable value for the DISPLAY variable. */ 2717 if (gethostname(hostname, sizeof(hostname)) < 0) 2718 fatal("gethostname: %.100s", strerror(errno)); 2719 /* 2720 * auth_display must be used as the displayname when the 2721 * authorization entry is added with xauth(1). This will be 2722 * different than the DISPLAY string for localhost displays. 2723 */ 2724 if (options.x11_use_localhost) { 2725 snprintf(display, sizeof display, "localhost:%u.%u", 2726 s->display_number, s->screen); 2727 snprintf(auth_display, sizeof auth_display, "unix:%u.%u", 2728 s->display_number, s->screen); 2729 s->display = xstrdup(display); 2730 s->auth_display = xstrdup(auth_display); 2731 } else { 2732 #ifdef IPADDR_IN_DISPLAY 2733 struct hostent *he; 2734 struct in_addr my_addr; 2735 2736 he = gethostbyname(hostname); 2737 if (he == NULL) { 2738 error("Can't get IP address for X11 DISPLAY."); 2739 packet_send_debug("Can't get IP address for X11 DISPLAY."); 2740 return 0; 2741 } 2742 memcpy(&my_addr, he->h_addr_list[0], sizeof(struct in_addr)); 2743 snprintf(display, sizeof display, "%.50s:%u.%u", inet_ntoa(my_addr), 2744 s->display_number, s->screen); 2745 #else 2746 snprintf(display, sizeof display, "%.400s:%u.%u", hostname, 2747 s->display_number, s->screen); 2748 #endif 2749 s->display = xstrdup(display); 2750 s->auth_display = xstrdup(display); 2751 } 2752 2753 return 1; 2754 } 2755 2756 static void 2757 do_authenticated2(Authctxt *authctxt) 2758 { 2759 server_loop2(authctxt); 2760 } 2761 2762 void 2763 do_cleanup(Authctxt *authctxt) 2764 { 2765 static int called = 0; 2766 2767 debug("do_cleanup"); 2768 2769 /* no cleanup if we're in the child for login shell */ 2770 if (is_child) 2771 return; 2772 2773 /* avoid double cleanup */ 2774 if (called) 2775 return; 2776 called = 1; 2777 2778 if (authctxt == NULL) 2779 return; 2780 2781 #ifdef USE_PAM 2782 if (options.use_pam) { 2783 sshpam_cleanup(); 2784 sshpam_thread_cleanup(); 2785 } 2786 #endif 2787 2788 if (!authctxt->authenticated) 2789 return; 2790 2791 #ifdef KRB5 2792 if (options.kerberos_ticket_cleanup && 2793 authctxt->krb5_ctx) 2794 krb5_cleanup_proc(authctxt); 2795 #endif 2796 2797 #ifdef GSSAPI 2798 if (compat20 && options.gss_cleanup_creds) 2799 ssh_gssapi_cleanup_creds(); 2800 #endif 2801 2802 /* remove agent socket */ 2803 auth_sock_cleanup_proc(authctxt->pw); 2804 2805 /* 2806 * Cleanup ptys/utmp only if privsep is disabled, 2807 * or if running in monitor. 2808 */ 2809 if (!use_privsep || mm_is_monitor()) 2810 session_destroy_all(session_pty_cleanup2); 2811 } 2812 2813 /* Return a name for the remote host that fits inside utmp_size */ 2814 2815 const char * 2816 session_get_remote_name_or_ip(struct ssh *ssh, u_int utmp_size, int use_dns) 2817 { 2818 const char *remote = ""; 2819 2820 if (utmp_size > 0) 2821 remote = auth_get_canonical_hostname(ssh, use_dns); 2822 if (utmp_size == 0 || strlen(remote) > utmp_size) 2823 remote = ssh_remote_ipaddr(ssh); 2824 return remote; 2825 } 2826 2827