session.c revision 294693
1/* $OpenBSD: session.c,v 1.270 2014/01/31 16:39:19 tedu 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: stable/10/crypto/openssh/session.c 294693 2016-01-24 22:28:18Z des $"); 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 <errno.h> 51#include <fcntl.h> 52#include <grp.h> 53#ifdef HAVE_PATHS_H 54#include <paths.h> 55#endif 56#include <pwd.h> 57#include <signal.h> 58#include <stdarg.h> 59#include <stdio.h> 60#include <stdlib.h> 61#include <string.h> 62#include <unistd.h> 63 64#include "openbsd-compat/sys-queue.h" 65#include "xmalloc.h" 66#include "ssh.h" 67#include "ssh1.h" 68#include "ssh2.h" 69#include "sshpty.h" 70#include "packet.h" 71#include "buffer.h" 72#include "match.h" 73#include "uidswap.h" 74#include "compat.h" 75#include "channels.h" 76#include "key.h" 77#include "cipher.h" 78#ifdef GSSAPI 79#include "ssh-gss.h" 80#endif 81#include "hostfile.h" 82#include "auth.h" 83#include "auth-options.h" 84#include "authfd.h" 85#include "pathnames.h" 86#include "log.h" 87#include "servconf.h" 88#include "sshlogin.h" 89#include "serverloop.h" 90#include "canohost.h" 91#include "misc.h" 92#include "session.h" 93#include "kex.h" 94#include "monitor_wrap.h" 95#include "sftp.h" 96 97#if defined(KRB5) && defined(USE_AFS) 98#include <kafs.h> 99#endif 100 101#ifdef WITH_SELINUX 102#include <selinux/selinux.h> 103#endif 104 105#define IS_INTERNAL_SFTP(c) \ 106 (!strncmp(c, INTERNAL_SFTP_NAME, sizeof(INTERNAL_SFTP_NAME) - 1) && \ 107 (c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\0' || \ 108 c[sizeof(INTERNAL_SFTP_NAME) - 1] == ' ' || \ 109 c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\t')) 110 111/* func */ 112 113Session *session_new(void); 114void session_set_fds(Session *, int, int, int, int, int); 115void session_pty_cleanup(Session *); 116void session_proctitle(Session *); 117int session_setup_x11fwd(Session *); 118int do_exec_pty(Session *, const char *); 119int do_exec_no_pty(Session *, const char *); 120int do_exec(Session *, const char *); 121void do_login(Session *, const char *); 122#ifdef LOGIN_NEEDS_UTMPX 123static void do_pre_login(Session *s); 124#endif 125void do_child(Session *, const char *); 126void do_motd(void); 127int check_quietlogin(Session *, const char *); 128 129static void do_authenticated1(Authctxt *); 130static void do_authenticated2(Authctxt *); 131 132static int session_pty_req(Session *); 133 134/* import */ 135extern ServerOptions options; 136extern char *__progname; 137extern int log_stderr; 138extern int debug_flag; 139extern u_int utmp_len; 140extern int startup_pipe; 141extern void destroy_sensitive_data(void); 142extern Buffer loginmsg; 143 144/* original command from peer. */ 145const char *original_command = NULL; 146 147/* data */ 148static int sessions_first_unused = -1; 149static int sessions_nalloc = 0; 150static Session *sessions = NULL; 151 152#define SUBSYSTEM_NONE 0 153#define SUBSYSTEM_EXT 1 154#define SUBSYSTEM_INT_SFTP 2 155#define SUBSYSTEM_INT_SFTP_ERROR 3 156 157#ifdef HAVE_LOGIN_CAP 158login_cap_t *lc; 159#endif 160 161static int is_child = 0; 162 163/* Name and directory of socket for authentication agent forwarding. */ 164static char *auth_sock_name = NULL; 165static char *auth_sock_dir = NULL; 166 167/* removes the agent forwarding socket */ 168 169static void 170auth_sock_cleanup_proc(struct passwd *pw) 171{ 172 if (auth_sock_name != NULL) { 173 temporarily_use_uid(pw); 174 unlink(auth_sock_name); 175 rmdir(auth_sock_dir); 176 auth_sock_name = NULL; 177 restore_uid(); 178 } 179} 180 181static int 182auth_input_request_forwarding(struct passwd * pw) 183{ 184 Channel *nc; 185 int sock = -1; 186 struct sockaddr_un sunaddr; 187 188 if (auth_sock_name != NULL) { 189 error("authentication forwarding requested twice."); 190 return 0; 191 } 192 193 /* Temporarily drop privileged uid for mkdir/bind. */ 194 temporarily_use_uid(pw); 195 196 /* Allocate a buffer for the socket name, and format the name. */ 197 auth_sock_dir = xstrdup("/tmp/ssh-XXXXXXXXXX"); 198 199 /* Create private directory for socket */ 200 if (mkdtemp(auth_sock_dir) == NULL) { 201 packet_send_debug("Agent forwarding disabled: " 202 "mkdtemp() failed: %.100s", strerror(errno)); 203 restore_uid(); 204 free(auth_sock_dir); 205 auth_sock_dir = NULL; 206 goto authsock_err; 207 } 208 209 xasprintf(&auth_sock_name, "%s/agent.%ld", 210 auth_sock_dir, (long) getpid()); 211 212 /* Create the socket. */ 213 sock = socket(AF_UNIX, SOCK_STREAM, 0); 214 if (sock < 0) { 215 error("socket: %.100s", strerror(errno)); 216 restore_uid(); 217 goto authsock_err; 218 } 219 220 /* Bind it to the name. */ 221 memset(&sunaddr, 0, sizeof(sunaddr)); 222 sunaddr.sun_family = AF_UNIX; 223 strlcpy(sunaddr.sun_path, auth_sock_name, sizeof(sunaddr.sun_path)); 224 225 if (bind(sock, (struct sockaddr *)&sunaddr, sizeof(sunaddr)) < 0) { 226 error("bind: %.100s", strerror(errno)); 227 restore_uid(); 228 goto authsock_err; 229 } 230 231 /* Restore the privileged uid. */ 232 restore_uid(); 233 234 /* Start listening on the socket. */ 235 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) { 236 error("listen: %.100s", strerror(errno)); 237 goto authsock_err; 238 } 239 240 /* Allocate a channel for the authentication agent socket. */ 241 nc = channel_new("auth socket", 242 SSH_CHANNEL_AUTH_SOCKET, sock, sock, -1, 243 CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 244 0, "auth socket", 1); 245 nc->path = xstrdup(auth_sock_name); 246 return 1; 247 248 authsock_err: 249 free(auth_sock_name); 250 if (auth_sock_dir != NULL) { 251 rmdir(auth_sock_dir); 252 free(auth_sock_dir); 253 } 254 if (sock != -1) 255 close(sock); 256 auth_sock_name = NULL; 257 auth_sock_dir = NULL; 258 return 0; 259} 260 261static void 262display_loginmsg(void) 263{ 264 if (buffer_len(&loginmsg) > 0) { 265 buffer_append(&loginmsg, "\0", 1); 266 printf("%s", (char *)buffer_ptr(&loginmsg)); 267 buffer_clear(&loginmsg); 268 } 269} 270 271void 272do_authenticated(Authctxt *authctxt) 273{ 274 setproctitle("%s", authctxt->pw->pw_name); 275 276 /* setup the channel layer */ 277 if (no_port_forwarding_flag || 278 (options.allow_tcp_forwarding & FORWARD_LOCAL) == 0) 279 channel_disable_adm_local_opens(); 280 else 281 channel_permit_all_opens(); 282 283 auth_debug_send(); 284 285 if (compat20) 286 do_authenticated2(authctxt); 287 else 288 do_authenticated1(authctxt); 289 290 do_cleanup(authctxt); 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 */ 299static void 300do_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 success = session_setup_x11fwd(s); 367 if (!success) { 368 free(s->auth_proto); 369 free(s->auth_data); 370 s->auth_proto = NULL; 371 s->auth_data = NULL; 372 } 373 break; 374 375 case SSH_CMSG_AGENT_REQUEST_FORWARDING: 376 if (!options.allow_agent_forwarding || 377 no_agent_forwarding_flag || compat13) { 378 debug("Authentication agent forwarding not permitted for this authentication."); 379 break; 380 } 381 debug("Received authentication agent forwarding request."); 382 success = auth_input_request_forwarding(s->pw); 383 break; 384 385 case SSH_CMSG_PORT_FORWARD_REQUEST: 386 if (no_port_forwarding_flag) { 387 debug("Port forwarding not permitted for this authentication."); 388 break; 389 } 390 if (!(options.allow_tcp_forwarding & FORWARD_REMOTE)) { 391 debug("Port forwarding not permitted."); 392 break; 393 } 394 debug("Received TCP/IP port forwarding request."); 395 if (channel_input_port_forward_request(s->pw->pw_uid == 0, 396 options.gateway_ports) < 0) { 397 debug("Port forwarding failed."); 398 break; 399 } 400 success = 1; 401 break; 402 403 case SSH_CMSG_MAX_PACKET_SIZE: 404 if (packet_set_maxsize(packet_get_int()) > 0) 405 success = 1; 406 break; 407 408 case SSH_CMSG_EXEC_SHELL: 409 case SSH_CMSG_EXEC_CMD: 410 if (type == SSH_CMSG_EXEC_CMD) { 411 command = packet_get_string(&dlen); 412 debug("Exec command '%.500s'", command); 413 if (do_exec(s, command) != 0) 414 packet_disconnect( 415 "command execution failed"); 416 free(command); 417 } else { 418 if (do_exec(s, NULL) != 0) 419 packet_disconnect( 420 "shell execution failed"); 421 } 422 packet_check_eom(); 423 session_close(s); 424 return; 425 426 default: 427 /* 428 * Any unknown messages in this phase are ignored, 429 * and a failure message is returned. 430 */ 431 logit("Unknown packet type received after authentication: %d", type); 432 } 433 packet_start(success ? SSH_SMSG_SUCCESS : SSH_SMSG_FAILURE); 434 packet_send(); 435 packet_write_wait(); 436 437 /* Enable compression now that we have replied if appropriate. */ 438 if (enable_compression_after_reply) { 439 enable_compression_after_reply = 0; 440 packet_start_compression(compression_level); 441 } 442 } 443} 444 445#define USE_PIPES 1 446/* 447 * This is called to fork and execute a command when we have no tty. This 448 * will call do_child from the child, and server_loop from the parent after 449 * setting up file descriptors and such. 450 */ 451int 452do_exec_no_pty(Session *s, const char *command) 453{ 454 pid_t pid; 455 456#ifdef USE_PIPES 457 int pin[2], pout[2], perr[2]; 458 459 if (s == NULL) 460 fatal("do_exec_no_pty: no session"); 461 462 /* Allocate pipes for communicating with the program. */ 463 if (pipe(pin) < 0) { 464 error("%s: pipe in: %.100s", __func__, strerror(errno)); 465 return -1; 466 } 467 if (pipe(pout) < 0) { 468 error("%s: pipe out: %.100s", __func__, strerror(errno)); 469 close(pin[0]); 470 close(pin[1]); 471 return -1; 472 } 473 if (pipe(perr) < 0) { 474 error("%s: pipe err: %.100s", __func__, 475 strerror(errno)); 476 close(pin[0]); 477 close(pin[1]); 478 close(pout[0]); 479 close(pout[1]); 480 return -1; 481 } 482#else 483 int inout[2], err[2]; 484 485 if (s == NULL) 486 fatal("do_exec_no_pty: no session"); 487 488 /* Uses socket pairs to communicate with the program. */ 489 if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) < 0) { 490 error("%s: socketpair #1: %.100s", __func__, strerror(errno)); 491 return -1; 492 } 493 if (socketpair(AF_UNIX, SOCK_STREAM, 0, err) < 0) { 494 error("%s: socketpair #2: %.100s", __func__, 495 strerror(errno)); 496 close(inout[0]); 497 close(inout[1]); 498 return -1; 499 } 500#endif 501 502 session_proctitle(s); 503 504 /* Fork the child. */ 505 switch ((pid = fork())) { 506 case -1: 507 error("%s: fork: %.100s", __func__, strerror(errno)); 508#ifdef USE_PIPES 509 close(pin[0]); 510 close(pin[1]); 511 close(pout[0]); 512 close(pout[1]); 513 close(perr[0]); 514 close(perr[1]); 515#else 516 close(inout[0]); 517 close(inout[1]); 518 close(err[0]); 519 close(err[1]); 520#endif 521 return -1; 522 case 0: 523 is_child = 1; 524 525 /* Child. Reinitialize the log since the pid has changed. */ 526 log_init(__progname, options.log_level, 527 options.log_facility, log_stderr); 528 529 /* 530 * Create a new session and process group since the 4.4BSD 531 * setlogin() affects the entire process group. 532 */ 533 if (setsid() < 0) 534 error("setsid failed: %.100s", strerror(errno)); 535 536#ifdef USE_PIPES 537 /* 538 * Redirect stdin. We close the parent side of the socket 539 * pair, and make the child side the standard input. 540 */ 541 close(pin[1]); 542 if (dup2(pin[0], 0) < 0) 543 perror("dup2 stdin"); 544 close(pin[0]); 545 546 /* Redirect stdout. */ 547 close(pout[0]); 548 if (dup2(pout[1], 1) < 0) 549 perror("dup2 stdout"); 550 close(pout[1]); 551 552 /* Redirect stderr. */ 553 close(perr[0]); 554 if (dup2(perr[1], 2) < 0) 555 perror("dup2 stderr"); 556 close(perr[1]); 557#else 558 /* 559 * Redirect stdin, stdout, and stderr. Stdin and stdout will 560 * use the same socket, as some programs (particularly rdist) 561 * seem to depend on it. 562 */ 563 close(inout[1]); 564 close(err[1]); 565 if (dup2(inout[0], 0) < 0) /* stdin */ 566 perror("dup2 stdin"); 567 if (dup2(inout[0], 1) < 0) /* stdout (same as stdin) */ 568 perror("dup2 stdout"); 569 close(inout[0]); 570 if (dup2(err[0], 2) < 0) /* stderr */ 571 perror("dup2 stderr"); 572 close(err[0]); 573#endif 574 575 576#ifdef _UNICOS 577 cray_init_job(s->pw); /* set up cray jid and tmpdir */ 578#endif 579 580 /* Do processing for the child (exec command etc). */ 581 do_child(s, command); 582 /* NOTREACHED */ 583 default: 584 break; 585 } 586 587#ifdef _UNICOS 588 signal(WJSIGNAL, cray_job_termination_handler); 589#endif /* _UNICOS */ 590#ifdef HAVE_CYGWIN 591 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); 592#endif 593 594 s->pid = pid; 595 /* Set interactive/non-interactive mode. */ 596 packet_set_interactive(s->display != NULL, 597 options.ip_qos_interactive, options.ip_qos_bulk); 598 599 /* 600 * Clear loginmsg, since it's the child's responsibility to display 601 * it to the user, otherwise multiple sessions may accumulate 602 * multiple copies of the login messages. 603 */ 604 buffer_clear(&loginmsg); 605 606#ifdef USE_PIPES 607 /* We are the parent. Close the child sides of the pipes. */ 608 close(pin[0]); 609 close(pout[1]); 610 close(perr[1]); 611 612 if (compat20) { 613 session_set_fds(s, pin[1], pout[0], perr[0], 614 s->is_subsystem, 0); 615 } else { 616 /* Enter the interactive session. */ 617 server_loop(pid, pin[1], pout[0], perr[0]); 618 /* server_loop has closed pin[1], pout[0], and perr[0]. */ 619 } 620#else 621 /* We are the parent. Close the child sides of the socket pairs. */ 622 close(inout[0]); 623 close(err[0]); 624 625 /* 626 * Enter the interactive session. Note: server_loop must be able to 627 * handle the case that fdin and fdout are the same. 628 */ 629 if (compat20) { 630 session_set_fds(s, inout[1], inout[1], err[1], 631 s->is_subsystem, 0); 632 } else { 633 server_loop(pid, inout[1], inout[1], err[1]); 634 /* server_loop has closed inout[1] and err[1]. */ 635 } 636#endif 637 return 0; 638} 639 640/* 641 * This is called to fork and execute a command when we have a tty. This 642 * will call do_child from the child, and server_loop from the parent after 643 * setting up file descriptors, controlling tty, updating wtmp, utmp, 644 * lastlog, and other such operations. 645 */ 646int 647do_exec_pty(Session *s, const char *command) 648{ 649 int fdout, ptyfd, ttyfd, ptymaster; 650 pid_t pid; 651 652 if (s == NULL) 653 fatal("do_exec_pty: no session"); 654 ptyfd = s->ptyfd; 655 ttyfd = s->ttyfd; 656 657 /* 658 * Create another descriptor of the pty master side for use as the 659 * standard input. We could use the original descriptor, but this 660 * simplifies code in server_loop. The descriptor is bidirectional. 661 * Do this before forking (and cleanup in the child) so as to 662 * detect and gracefully fail out-of-fd conditions. 663 */ 664 if ((fdout = dup(ptyfd)) < 0) { 665 error("%s: dup #1: %s", __func__, strerror(errno)); 666 close(ttyfd); 667 close(ptyfd); 668 return -1; 669 } 670 /* we keep a reference to the pty master */ 671 if ((ptymaster = dup(ptyfd)) < 0) { 672 error("%s: dup #2: %s", __func__, strerror(errno)); 673 close(ttyfd); 674 close(ptyfd); 675 close(fdout); 676 return -1; 677 } 678 679 /* Fork the child. */ 680 switch ((pid = fork())) { 681 case -1: 682 error("%s: fork: %.100s", __func__, strerror(errno)); 683 close(fdout); 684 close(ptymaster); 685 close(ttyfd); 686 close(ptyfd); 687 return -1; 688 case 0: 689 is_child = 1; 690 691 close(fdout); 692 close(ptymaster); 693 694 /* Child. Reinitialize the log because the pid has changed. */ 695 log_init(__progname, options.log_level, 696 options.log_facility, log_stderr); 697 /* Close the master side of the pseudo tty. */ 698 close(ptyfd); 699 700 /* Make the pseudo tty our controlling tty. */ 701 pty_make_controlling_tty(&ttyfd, s->tty); 702 703 /* Redirect stdin/stdout/stderr from the pseudo tty. */ 704 if (dup2(ttyfd, 0) < 0) 705 error("dup2 stdin: %s", strerror(errno)); 706 if (dup2(ttyfd, 1) < 0) 707 error("dup2 stdout: %s", strerror(errno)); 708 if (dup2(ttyfd, 2) < 0) 709 error("dup2 stderr: %s", strerror(errno)); 710 711 /* Close the extra descriptor for the pseudo tty. */ 712 close(ttyfd); 713 714 /* record login, etc. similar to login(1) */ 715#ifndef HAVE_OSF_SIA 716 if (!(options.use_login && command == NULL)) { 717#ifdef _UNICOS 718 cray_init_job(s->pw); /* set up cray jid and tmpdir */ 719#endif /* _UNICOS */ 720 do_login(s, command); 721 } 722# ifdef LOGIN_NEEDS_UTMPX 723 else 724 do_pre_login(s); 725# endif 726#endif 727 /* 728 * Do common processing for the child, such as execing 729 * the command. 730 */ 731 do_child(s, command); 732 /* NOTREACHED */ 733 default: 734 break; 735 } 736 737#ifdef _UNICOS 738 signal(WJSIGNAL, cray_job_termination_handler); 739#endif /* _UNICOS */ 740#ifdef HAVE_CYGWIN 741 cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); 742#endif 743 744 s->pid = pid; 745 746 /* Parent. Close the slave side of the pseudo tty. */ 747 close(ttyfd); 748 749 /* Enter interactive session. */ 750 s->ptymaster = ptymaster; 751 packet_set_interactive(1, 752 options.ip_qos_interactive, options.ip_qos_bulk); 753 if (compat20) { 754 session_set_fds(s, ptyfd, fdout, -1, 1, 1); 755 } else { 756 server_loop(pid, ptyfd, fdout, -1); 757 /* server_loop _has_ closed ptyfd and fdout. */ 758 } 759 return 0; 760} 761 762#ifdef LOGIN_NEEDS_UTMPX 763static void 764do_pre_login(Session *s) 765{ 766 socklen_t fromlen; 767 struct sockaddr_storage from; 768 pid_t pid = getpid(); 769 770 /* 771 * Get IP address of client. If the connection is not a socket, let 772 * the address be 0.0.0.0. 773 */ 774 memset(&from, 0, sizeof(from)); 775 fromlen = sizeof(from); 776 if (packet_connection_is_on_socket()) { 777 if (getpeername(packet_get_connection_in(), 778 (struct sockaddr *)&from, &fromlen) < 0) { 779 debug("getpeername: %.100s", strerror(errno)); 780 cleanup_exit(255); 781 } 782 } 783 784 record_utmp_only(pid, s->tty, s->pw->pw_name, 785 get_remote_name_or_ip(utmp_len, options.use_dns), 786 (struct sockaddr *)&from, fromlen); 787} 788#endif 789 790/* 791 * This is called to fork and execute a command. If another command is 792 * to be forced, execute that instead. 793 */ 794int 795do_exec(Session *s, const char *command) 796{ 797 int ret; 798 const char *forced = NULL; 799 char session_type[1024], *tty = NULL; 800 801 if (options.adm_forced_command) { 802 original_command = command; 803 command = options.adm_forced_command; 804 forced = "(config)"; 805 } else if (forced_command) { 806 original_command = command; 807 command = forced_command; 808 forced = "(key-option)"; 809 } 810 if (forced != NULL) { 811 if (IS_INTERNAL_SFTP(command)) { 812 s->is_subsystem = s->is_subsystem ? 813 SUBSYSTEM_INT_SFTP : SUBSYSTEM_INT_SFTP_ERROR; 814 } else if (s->is_subsystem) 815 s->is_subsystem = SUBSYSTEM_EXT; 816 snprintf(session_type, sizeof(session_type), 817 "forced-command %s '%.900s'", forced, command); 818 } else if (s->is_subsystem) { 819 snprintf(session_type, sizeof(session_type), 820 "subsystem '%.900s'", s->subsys); 821 } else if (command == NULL) { 822 snprintf(session_type, sizeof(session_type), "shell"); 823 } else { 824 /* NB. we don't log unforced commands to preserve privacy */ 825 snprintf(session_type, sizeof(session_type), "command"); 826 } 827 828 if (s->ttyfd != -1) { 829 tty = s->tty; 830 if (strncmp(tty, "/dev/", 5) == 0) 831 tty += 5; 832 } 833 834 verbose("Starting session: %s%s%s for %s from %.200s port %d", 835 session_type, 836 tty == NULL ? "" : " on ", 837 tty == NULL ? "" : tty, 838 s->pw->pw_name, 839 get_remote_ipaddr(), 840 get_remote_port()); 841 842#ifdef SSH_AUDIT_EVENTS 843 if (command != NULL) 844 PRIVSEP(audit_run_command(command)); 845 else if (s->ttyfd == -1) { 846 char *shell = s->pw->pw_shell; 847 848 if (shell[0] == '\0') /* empty shell means /bin/sh */ 849 shell =_PATH_BSHELL; 850 PRIVSEP(audit_run_command(shell)); 851 } 852#endif 853 if (s->ttyfd != -1) 854 ret = do_exec_pty(s, command); 855 else 856 ret = do_exec_no_pty(s, command); 857 858 original_command = NULL; 859 860 /* 861 * Clear loginmsg: it's the child's responsibility to display 862 * it to the user, otherwise multiple sessions may accumulate 863 * multiple copies of the login messages. 864 */ 865 buffer_clear(&loginmsg); 866 867 return ret; 868} 869 870/* administrative, login(1)-like work */ 871void 872do_login(Session *s, const char *command) 873{ 874 socklen_t fromlen; 875 struct sockaddr_storage from; 876 struct passwd * pw = s->pw; 877 pid_t pid = getpid(); 878 879 /* 880 * Get IP address of client. If the connection is not a socket, let 881 * the address be 0.0.0.0. 882 */ 883 memset(&from, 0, sizeof(from)); 884 fromlen = sizeof(from); 885 if (packet_connection_is_on_socket()) { 886 if (getpeername(packet_get_connection_in(), 887 (struct sockaddr *)&from, &fromlen) < 0) { 888 debug("getpeername: %.100s", strerror(errno)); 889 cleanup_exit(255); 890 } 891 } 892 893 /* Record that there was a login on that tty from the remote host. */ 894 if (!use_privsep) 895 record_login(pid, s->tty, pw->pw_name, pw->pw_uid, 896 get_remote_name_or_ip(utmp_len, 897 options.use_dns), 898 (struct sockaddr *)&from, fromlen); 899 900#ifdef USE_PAM 901 /* 902 * If password change is needed, do it now. 903 * This needs to occur before the ~/.hushlogin check. 904 */ 905 if (options.use_pam && !use_privsep && s->authctxt->force_pwchange) { 906 display_loginmsg(); 907 do_pam_chauthtok(); 908 s->authctxt->force_pwchange = 0; 909 /* XXX - signal [net] parent to enable forwardings */ 910 } 911#endif 912 913 if (check_quietlogin(s, command)) 914 return; 915 916 display_loginmsg(); 917 918 do_motd(); 919} 920 921/* 922 * Display the message of the day. 923 */ 924void 925do_motd(void) 926{ 927 FILE *f; 928 char buf[256]; 929 930 if (options.print_motd) { 931#ifdef HAVE_LOGIN_CAP 932 f = fopen(login_getcapstr(lc, "welcome", "/etc/motd", 933 "/etc/motd"), "r"); 934#else 935 f = fopen("/etc/motd", "r"); 936#endif 937 if (f) { 938 while (fgets(buf, sizeof(buf), f)) 939 fputs(buf, stdout); 940 fclose(f); 941 } 942 } 943} 944 945 946/* 947 * Check for quiet login, either .hushlogin or command given. 948 */ 949int 950check_quietlogin(Session *s, const char *command) 951{ 952 char buf[256]; 953 struct passwd *pw = s->pw; 954 struct stat st; 955 956 /* Return 1 if .hushlogin exists or a command given. */ 957 if (command != NULL) 958 return 1; 959 snprintf(buf, sizeof(buf), "%.200s/.hushlogin", pw->pw_dir); 960#ifdef HAVE_LOGIN_CAP 961 if (login_getcapbool(lc, "hushlogin", 0) || stat(buf, &st) >= 0) 962 return 1; 963#else 964 if (stat(buf, &st) >= 0) 965 return 1; 966#endif 967 return 0; 968} 969 970/* 971 * Sets the value of the given variable in the environment. If the variable 972 * already exists, its value is overridden. 973 */ 974void 975child_set_env(char ***envp, u_int *envsizep, const char *name, 976 const char *value) 977{ 978 char **env; 979 u_int envsize; 980 u_int i, namelen; 981 982 if (strchr(name, '=') != NULL) { 983 error("Invalid environment variable \"%.100s\"", name); 984 return; 985 } 986 987 /* 988 * If we're passed an uninitialized list, allocate a single null 989 * entry before continuing. 990 */ 991 if (*envp == NULL && *envsizep == 0) { 992 *envp = xmalloc(sizeof(char *)); 993 *envp[0] = NULL; 994 *envsizep = 1; 995 } 996 997 /* 998 * Find the slot where the value should be stored. If the variable 999 * already exists, we reuse the slot; otherwise we append a new slot 1000 * at the end of the array, expanding if necessary. 1001 */ 1002 env = *envp; 1003 namelen = strlen(name); 1004 for (i = 0; env[i]; i++) 1005 if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=') 1006 break; 1007 if (env[i]) { 1008 /* Reuse the slot. */ 1009 free(env[i]); 1010 } else { 1011 /* New variable. Expand if necessary. */ 1012 envsize = *envsizep; 1013 if (i >= envsize - 1) { 1014 if (envsize >= 1000) 1015 fatal("child_set_env: too many env vars"); 1016 envsize += 50; 1017 env = (*envp) = xrealloc(env, envsize, sizeof(char *)); 1018 *envsizep = envsize; 1019 } 1020 /* Need to set the NULL pointer at end of array beyond the new slot. */ 1021 env[i + 1] = NULL; 1022 } 1023 1024 /* Allocate space and format the variable in the appropriate slot. */ 1025 env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1); 1026 snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value); 1027} 1028 1029/* 1030 * Reads environment variables from the given file and adds/overrides them 1031 * into the environment. If the file does not exist, this does nothing. 1032 * Otherwise, it must consist of empty lines, comments (line starts with '#') 1033 * and assignments of the form name=value. No other forms are allowed. 1034 */ 1035static void 1036read_environment_file(char ***env, u_int *envsize, 1037 const char *filename) 1038{ 1039 FILE *f; 1040 char buf[4096]; 1041 char *cp, *value; 1042 u_int lineno = 0; 1043 1044 f = fopen(filename, "r"); 1045 if (!f) 1046 return; 1047 1048 while (fgets(buf, sizeof(buf), f)) { 1049 if (++lineno > 1000) 1050 fatal("Too many lines in environment file %s", filename); 1051 for (cp = buf; *cp == ' ' || *cp == '\t'; cp++) 1052 ; 1053 if (!*cp || *cp == '#' || *cp == '\n') 1054 continue; 1055 1056 cp[strcspn(cp, "\n")] = '\0'; 1057 1058 value = strchr(cp, '='); 1059 if (value == NULL) { 1060 fprintf(stderr, "Bad line %u in %.100s\n", lineno, 1061 filename); 1062 continue; 1063 } 1064 /* 1065 * Replace the equals sign by nul, and advance value to 1066 * the value string. 1067 */ 1068 *value = '\0'; 1069 value++; 1070 child_set_env(env, envsize, cp, value); 1071 } 1072 fclose(f); 1073} 1074 1075#ifdef HAVE_ETC_DEFAULT_LOGIN 1076/* 1077 * Return named variable from specified environment, or NULL if not present. 1078 */ 1079static char * 1080child_get_env(char **env, const char *name) 1081{ 1082 int i; 1083 size_t len; 1084 1085 len = strlen(name); 1086 for (i=0; env[i] != NULL; i++) 1087 if (strncmp(name, env[i], len) == 0 && env[i][len] == '=') 1088 return(env[i] + len + 1); 1089 return NULL; 1090} 1091 1092/* 1093 * Read /etc/default/login. 1094 * We pick up the PATH (or SUPATH for root) and UMASK. 1095 */ 1096static void 1097read_etc_default_login(char ***env, u_int *envsize, uid_t uid) 1098{ 1099 char **tmpenv = NULL, *var; 1100 u_int i, tmpenvsize = 0; 1101 u_long mask; 1102 1103 /* 1104 * We don't want to copy the whole file to the child's environment, 1105 * so we use a temporary environment and copy the variables we're 1106 * interested in. 1107 */ 1108 read_environment_file(&tmpenv, &tmpenvsize, "/etc/default/login"); 1109 1110 if (tmpenv == NULL) 1111 return; 1112 1113 if (uid == 0) 1114 var = child_get_env(tmpenv, "SUPATH"); 1115 else 1116 var = child_get_env(tmpenv, "PATH"); 1117 if (var != NULL) 1118 child_set_env(env, envsize, "PATH", var); 1119 1120 if ((var = child_get_env(tmpenv, "UMASK")) != NULL) 1121 if (sscanf(var, "%5lo", &mask) == 1) 1122 umask((mode_t)mask); 1123 1124 for (i = 0; tmpenv[i] != NULL; i++) 1125 free(tmpenv[i]); 1126 free(tmpenv); 1127} 1128#endif /* HAVE_ETC_DEFAULT_LOGIN */ 1129 1130void 1131copy_environment(char **source, char ***env, u_int *envsize) 1132{ 1133 char *var_name, *var_val; 1134 int i; 1135 1136 if (source == NULL) 1137 return; 1138 1139 for(i = 0; source[i] != NULL; i++) { 1140 var_name = xstrdup(source[i]); 1141 if ((var_val = strstr(var_name, "=")) == NULL) { 1142 free(var_name); 1143 continue; 1144 } 1145 *var_val++ = '\0'; 1146 1147 debug3("Copy environment: %s=%s", var_name, var_val); 1148 child_set_env(env, envsize, var_name, var_val); 1149 1150 free(var_name); 1151 } 1152} 1153 1154static char ** 1155do_setup_env(Session *s, const char *shell) 1156{ 1157 char buf[256]; 1158 u_int i, envsize; 1159 char **env, *laddr; 1160 struct passwd *pw = s->pw; 1161#if !defined (HAVE_LOGIN_CAP) && !defined (HAVE_CYGWIN) 1162 char *path = NULL; 1163#else 1164 extern char **environ; 1165 char **senv, **var; 1166#endif 1167 1168 /* Initialize the environment. */ 1169 envsize = 100; 1170 env = xcalloc(envsize, sizeof(char *)); 1171 env[0] = NULL; 1172 1173#ifdef HAVE_CYGWIN 1174 /* 1175 * The Windows environment contains some setting which are 1176 * important for a running system. They must not be dropped. 1177 */ 1178 { 1179 char **p; 1180 1181 p = fetch_windows_environment(); 1182 copy_environment(p, &env, &envsize); 1183 free_windows_environment(p); 1184 } 1185#endif 1186 1187 if (getenv("TZ")) 1188 child_set_env(&env, &envsize, "TZ", getenv("TZ")); 1189 1190#ifdef GSSAPI 1191 /* Allow any GSSAPI methods that we've used to alter 1192 * the childs environment as they see fit 1193 */ 1194 ssh_gssapi_do_child(&env, &envsize); 1195#endif 1196 1197 if (!options.use_login) { 1198 /* Set basic environment. */ 1199 for (i = 0; i < s->num_env; i++) 1200 child_set_env(&env, &envsize, s->env[i].name, 1201 s->env[i].val); 1202 1203 child_set_env(&env, &envsize, "USER", pw->pw_name); 1204 child_set_env(&env, &envsize, "LOGNAME", pw->pw_name); 1205#ifdef _AIX 1206 child_set_env(&env, &envsize, "LOGIN", pw->pw_name); 1207#endif 1208 child_set_env(&env, &envsize, "HOME", pw->pw_dir); 1209 snprintf(buf, sizeof buf, "%.200s/%.50s", 1210 _PATH_MAILDIR, pw->pw_name); 1211 child_set_env(&env, &envsize, "MAIL", buf); 1212#ifdef HAVE_LOGIN_CAP 1213 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); 1214 child_set_env(&env, &envsize, "TERM", "su"); 1215 senv = environ; 1216 environ = xmalloc(sizeof(char *)); 1217 *environ = NULL; 1218 (void) setusercontext(lc, pw, pw->pw_uid, 1219 LOGIN_SETENV|LOGIN_SETPATH); 1220 copy_environment(environ, &env, &envsize); 1221 for (var = environ; *var != NULL; ++var) 1222 free(*var); 1223 free(environ); 1224 environ = senv; 1225#else /* HAVE_LOGIN_CAP */ 1226# ifndef HAVE_CYGWIN 1227 /* 1228 * There's no standard path on Windows. The path contains 1229 * important components pointing to the system directories, 1230 * needed for loading shared libraries. So the path better 1231 * remains intact here. 1232 */ 1233# ifdef HAVE_ETC_DEFAULT_LOGIN 1234 read_etc_default_login(&env, &envsize, pw->pw_uid); 1235 path = child_get_env(env, "PATH"); 1236# endif /* HAVE_ETC_DEFAULT_LOGIN */ 1237 if (path == NULL || *path == '\0') { 1238 child_set_env(&env, &envsize, "PATH", 1239 s->pw->pw_uid == 0 ? 1240 SUPERUSER_PATH : _PATH_STDPATH); 1241 } 1242# endif /* HAVE_CYGWIN */ 1243#endif /* HAVE_LOGIN_CAP */ 1244 1245 /* Normal systems set SHELL by default. */ 1246 child_set_env(&env, &envsize, "SHELL", shell); 1247 } 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 get_remote_ipaddr(), get_remote_port(), get_local_port()); 1270 child_set_env(&env, &envsize, "SSH_CLIENT", buf); 1271 1272 laddr = get_local_ipaddr(packet_get_connection_in()); 1273 snprintf(buf, sizeof buf, "%.50s %d %.50s %d", 1274 get_remote_ipaddr(), get_remote_port(), laddr, get_local_port()); 1275 free(laddr); 1276 child_set_env(&env, &envsize, "SSH_CONNECTION", buf); 1277 1278 if (s->ttyfd != -1) 1279 child_set_env(&env, &envsize, "SSH_TTY", s->tty); 1280 if (s->term) 1281 child_set_env(&env, &envsize, "TERM", s->term); 1282 if (s->display) 1283 child_set_env(&env, &envsize, "DISPLAY", s->display); 1284 if (original_command) 1285 child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND", 1286 original_command); 1287 1288#ifdef _UNICOS 1289 if (cray_tmpdir[0] != '\0') 1290 child_set_env(&env, &envsize, "TMPDIR", cray_tmpdir); 1291#endif /* _UNICOS */ 1292 1293 /* 1294 * Since we clear KRB5CCNAME at startup, if it's set now then it 1295 * must have been set by a native authentication method (eg AIX or 1296 * SIA), so copy it to the child. 1297 */ 1298 { 1299 char *cp; 1300 1301 if ((cp = getenv("KRB5CCNAME")) != NULL) 1302 child_set_env(&env, &envsize, "KRB5CCNAME", cp); 1303 } 1304 1305#ifdef _AIX 1306 { 1307 char *cp; 1308 1309 if ((cp = getenv("AUTHSTATE")) != NULL) 1310 child_set_env(&env, &envsize, "AUTHSTATE", cp); 1311 read_environment_file(&env, &envsize, "/etc/environment"); 1312 } 1313#endif 1314#ifdef KRB5 1315 if (s->authctxt->krb5_ccname) 1316 child_set_env(&env, &envsize, "KRB5CCNAME", 1317 s->authctxt->krb5_ccname); 1318#endif 1319#ifdef USE_PAM 1320 /* 1321 * Pull in any environment variables that may have 1322 * been set by PAM. 1323 */ 1324 if (options.use_pam) { 1325 char **p; 1326 1327 p = fetch_pam_child_environment(); 1328 copy_environment(p, &env, &envsize); 1329 free_pam_environment(p); 1330 1331 p = fetch_pam_environment(); 1332 copy_environment(p, &env, &envsize); 1333 free_pam_environment(p); 1334 } 1335#endif /* USE_PAM */ 1336 1337 if (auth_sock_name != NULL) 1338 child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME, 1339 auth_sock_name); 1340 1341 /* read $HOME/.ssh/environment. */ 1342 if (options.permit_user_env && !options.use_login) { 1343 snprintf(buf, sizeof buf, "%.200s/.ssh/environment", 1344 strcmp(pw->pw_dir, "/") ? pw->pw_dir : ""); 1345 read_environment_file(&env, &envsize, buf); 1346 } 1347 if (debug_flag) { 1348 /* dump the environment */ 1349 fprintf(stderr, "Environment:\n"); 1350 for (i = 0; env[i]; i++) 1351 fprintf(stderr, " %.200s\n", env[i]); 1352 } 1353 return env; 1354} 1355 1356/* 1357 * Run $HOME/.ssh/rc, /etc/ssh/sshrc, or xauth (whichever is found 1358 * first in this order). 1359 */ 1360static void 1361do_rc_files(Session *s, const char *shell) 1362{ 1363 FILE *f = NULL; 1364 char cmd[1024]; 1365 int do_xauth; 1366 struct stat st; 1367 1368 do_xauth = 1369 s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL; 1370 1371 /* ignore _PATH_SSH_USER_RC for subsystems and admin forced commands */ 1372 if (!s->is_subsystem && options.adm_forced_command == NULL && 1373 !no_user_rc && stat(_PATH_SSH_USER_RC, &st) >= 0) { 1374 snprintf(cmd, sizeof cmd, "%s -c '%s %s'", 1375 shell, _PATH_BSHELL, _PATH_SSH_USER_RC); 1376 if (debug_flag) 1377 fprintf(stderr, "Running %s\n", cmd); 1378 f = popen(cmd, "w"); 1379 if (f) { 1380 if (do_xauth) 1381 fprintf(f, "%s %s\n", s->auth_proto, 1382 s->auth_data); 1383 pclose(f); 1384 } else 1385 fprintf(stderr, "Could not run %s\n", 1386 _PATH_SSH_USER_RC); 1387 } else if (stat(_PATH_SSH_SYSTEM_RC, &st) >= 0) { 1388 if (debug_flag) 1389 fprintf(stderr, "Running %s %s\n", _PATH_BSHELL, 1390 _PATH_SSH_SYSTEM_RC); 1391 f = popen(_PATH_BSHELL " " _PATH_SSH_SYSTEM_RC, "w"); 1392 if (f) { 1393 if (do_xauth) 1394 fprintf(f, "%s %s\n", s->auth_proto, 1395 s->auth_data); 1396 pclose(f); 1397 } else 1398 fprintf(stderr, "Could not run %s\n", 1399 _PATH_SSH_SYSTEM_RC); 1400 } else if (do_xauth && options.xauth_location != NULL) { 1401 /* Add authority data to .Xauthority if appropriate. */ 1402 if (debug_flag) { 1403 fprintf(stderr, 1404 "Running %.500s remove %.100s\n", 1405 options.xauth_location, s->auth_display); 1406 fprintf(stderr, 1407 "%.500s add %.100s %.100s %.100s\n", 1408 options.xauth_location, s->auth_display, 1409 s->auth_proto, s->auth_data); 1410 } 1411 snprintf(cmd, sizeof cmd, "%s -q -", 1412 options.xauth_location); 1413 f = popen(cmd, "w"); 1414 if (f) { 1415 fprintf(f, "remove %s\n", 1416 s->auth_display); 1417 fprintf(f, "add %s %s %s\n", 1418 s->auth_display, s->auth_proto, 1419 s->auth_data); 1420 pclose(f); 1421 } else { 1422 fprintf(stderr, "Could not run %s\n", 1423 cmd); 1424 } 1425 } 1426} 1427 1428static void 1429do_nologin(struct passwd *pw) 1430{ 1431 FILE *f = NULL; 1432 char buf[1024], *nl, *def_nl = _PATH_NOLOGIN; 1433 struct stat sb; 1434 1435#ifdef HAVE_LOGIN_CAP 1436 if (login_getcapbool(lc, "ignorenologin", 0) || pw->pw_uid == 0) 1437 return; 1438 nl = login_getcapstr(lc, "nologin", def_nl, def_nl); 1439#else 1440 if (pw->pw_uid == 0) 1441 return; 1442 nl = def_nl; 1443#endif 1444 if (stat(nl, &sb) == -1) { 1445 if (nl != def_nl) 1446 free(nl); 1447 return; 1448 } 1449 1450 /* /etc/nologin exists. Print its contents if we can and exit. */ 1451 logit("User %.100s not allowed because %s exists", pw->pw_name, nl); 1452 if ((f = fopen(nl, "r")) != NULL) { 1453 while (fgets(buf, sizeof(buf), f)) 1454 fputs(buf, stderr); 1455 fclose(f); 1456 } 1457 exit(254); 1458} 1459 1460/* 1461 * Chroot into a directory after checking it for safety: all path components 1462 * must be root-owned directories with strict permissions. 1463 */ 1464static void 1465safely_chroot(const char *path, uid_t uid) 1466{ 1467 const char *cp; 1468 char component[MAXPATHLEN]; 1469 struct stat st; 1470 1471 if (*path != '/') 1472 fatal("chroot path does not begin at root"); 1473 if (strlen(path) >= sizeof(component)) 1474 fatal("chroot path too long"); 1475 1476 /* 1477 * Descend the path, checking that each component is a 1478 * root-owned directory with strict permissions. 1479 */ 1480 for (cp = path; cp != NULL;) { 1481 if ((cp = strchr(cp, '/')) == NULL) 1482 strlcpy(component, path, sizeof(component)); 1483 else { 1484 cp++; 1485 memcpy(component, path, cp - path); 1486 component[cp - path] = '\0'; 1487 } 1488 1489 debug3("%s: checking '%s'", __func__, component); 1490 1491 if (stat(component, &st) != 0) 1492 fatal("%s: stat(\"%s\"): %s", __func__, 1493 component, strerror(errno)); 1494 if (st.st_uid != 0 || (st.st_mode & 022) != 0) 1495 fatal("bad ownership or modes for chroot " 1496 "directory %s\"%s\"", 1497 cp == NULL ? "" : "component ", component); 1498 if (!S_ISDIR(st.st_mode)) 1499 fatal("chroot path %s\"%s\" is not a directory", 1500 cp == NULL ? "" : "component ", component); 1501 1502 } 1503 1504 if (chdir(path) == -1) 1505 fatal("Unable to chdir to chroot path \"%s\": " 1506 "%s", path, strerror(errno)); 1507 if (chroot(path) == -1) 1508 fatal("chroot(\"%s\"): %s", path, strerror(errno)); 1509 if (chdir("/") == -1) 1510 fatal("%s: chdir(/) after chroot: %s", 1511 __func__, strerror(errno)); 1512 verbose("Changed root directory to \"%s\"", path); 1513} 1514 1515/* Set login name, uid, gid, and groups. */ 1516void 1517do_setusercontext(struct passwd *pw) 1518{ 1519 char *chroot_path, *tmp; 1520 1521 platform_setusercontext(pw); 1522 1523 if (platform_privileged_uidswap()) { 1524#ifdef HAVE_LOGIN_CAP 1525 if (setusercontext(lc, pw, pw->pw_uid, 1526 (LOGIN_SETALL & ~(LOGIN_SETENV|LOGIN_SETPATH|LOGIN_SETUSER))) < 0) { 1527 perror("unable to set user context"); 1528 exit(1); 1529 } 1530#else 1531 if (setlogin(pw->pw_name) < 0) 1532 error("setlogin failed: %s", strerror(errno)); 1533 if (setgid(pw->pw_gid) < 0) { 1534 perror("setgid"); 1535 exit(1); 1536 } 1537 /* Initialize the group list. */ 1538 if (initgroups(pw->pw_name, pw->pw_gid) < 0) { 1539 perror("initgroups"); 1540 exit(1); 1541 } 1542 endgrent(); 1543#endif 1544 1545 platform_setusercontext_post_groups(pw); 1546 1547 if (options.chroot_directory != NULL && 1548 strcasecmp(options.chroot_directory, "none") != 0) { 1549 tmp = tilde_expand_filename(options.chroot_directory, 1550 pw->pw_uid); 1551 chroot_path = percent_expand(tmp, "h", pw->pw_dir, 1552 "u", pw->pw_name, (char *)NULL); 1553 safely_chroot(chroot_path, pw->pw_uid); 1554 free(tmp); 1555 free(chroot_path); 1556 /* Make sure we don't attempt to chroot again */ 1557 free(options.chroot_directory); 1558 options.chroot_directory = NULL; 1559 } 1560 1561#ifdef HAVE_LOGIN_CAP 1562 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUSER) < 0) { 1563 perror("unable to set user context (setuser)"); 1564 exit(1); 1565 } 1566 /* 1567 * FreeBSD's setusercontext() will not apply the user's 1568 * own umask setting unless running with the user's UID. 1569 */ 1570 (void) setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUMASK); 1571#else 1572# ifdef USE_LIBIAF 1573 if (set_id(pw->pw_name) != 0) { 1574 fatal("set_id(%s) Failed", pw->pw_name); 1575 } 1576# endif /* USE_LIBIAF */ 1577 /* Permanently switch to the desired uid. */ 1578 permanently_set_uid(pw); 1579#endif 1580 } else if (options.chroot_directory != NULL && 1581 strcasecmp(options.chroot_directory, "none") != 0) { 1582 fatal("server lacks privileges to chroot to ChrootDirectory"); 1583 } 1584 1585 if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) 1586 fatal("Failed to set uids to %u.", (u_int) pw->pw_uid); 1587} 1588 1589static void 1590do_pwchange(Session *s) 1591{ 1592 fflush(NULL); 1593 fprintf(stderr, "WARNING: Your password has expired.\n"); 1594 if (s->ttyfd != -1) { 1595 fprintf(stderr, 1596 "You must change your password now and login again!\n"); 1597#ifdef WITH_SELINUX 1598 setexeccon(NULL); 1599#endif 1600#ifdef PASSWD_NEEDS_USERNAME 1601 execl(_PATH_PASSWD_PROG, "passwd", s->pw->pw_name, 1602 (char *)NULL); 1603#else 1604 execl(_PATH_PASSWD_PROG, "passwd", (char *)NULL); 1605#endif 1606 perror("passwd"); 1607 } else { 1608 fprintf(stderr, 1609 "Password change required but no TTY available.\n"); 1610 } 1611 exit(1); 1612} 1613 1614static void 1615launch_login(struct passwd *pw, const char *hostname) 1616{ 1617 /* Launch login(1). */ 1618 1619 execl(LOGIN_PROGRAM, "login", "-h", hostname, 1620#ifdef xxxLOGIN_NEEDS_TERM 1621 (s->term ? s->term : "unknown"), 1622#endif /* LOGIN_NEEDS_TERM */ 1623#ifdef LOGIN_NO_ENDOPT 1624 "-p", "-f", pw->pw_name, (char *)NULL); 1625#else 1626 "-p", "-f", "--", pw->pw_name, (char *)NULL); 1627#endif 1628 1629 /* Login couldn't be executed, die. */ 1630 1631 perror("login"); 1632 exit(1); 1633} 1634 1635static void 1636child_close_fds(void) 1637{ 1638 extern AuthenticationConnection *auth_conn; 1639 1640 if (auth_conn) { 1641 ssh_close_authentication_connection(auth_conn); 1642 auth_conn = NULL; 1643 } 1644 1645 if (packet_get_connection_in() == packet_get_connection_out()) 1646 close(packet_get_connection_in()); 1647 else { 1648 close(packet_get_connection_in()); 1649 close(packet_get_connection_out()); 1650 } 1651 /* 1652 * Close all descriptors related to channels. They will still remain 1653 * open in the parent. 1654 */ 1655 /* XXX better use close-on-exec? -markus */ 1656 channel_close_all(); 1657 1658 /* 1659 * Close any extra file descriptors. Note that there may still be 1660 * descriptors left by system functions. They will be closed later. 1661 */ 1662 endpwent(); 1663 1664 /* 1665 * Close any extra open file descriptors so that we don't have them 1666 * hanging around in clients. Note that we want to do this after 1667 * initgroups, because at least on Solaris 2.3 it leaves file 1668 * descriptors open. 1669 */ 1670 closefrom(STDERR_FILENO + 1); 1671} 1672 1673/* 1674 * Performs common processing for the child, such as setting up the 1675 * environment, closing extra file descriptors, setting the user and group 1676 * ids, and executing the command or shell. 1677 */ 1678#define ARGV_MAX 10 1679void 1680do_child(Session *s, const char *command) 1681{ 1682 extern char **environ; 1683 char **env; 1684 char *argv[ARGV_MAX]; 1685 const char *shell, *shell0, *hostname = NULL; 1686 struct passwd *pw = s->pw; 1687 int r = 0; 1688 1689 /* remove hostkey from the child's memory */ 1690 destroy_sensitive_data(); 1691 1692 /* Force a password change */ 1693 if (s->authctxt->force_pwchange) { 1694 do_setusercontext(pw); 1695 child_close_fds(); 1696 do_pwchange(s); 1697 exit(1); 1698 } 1699 1700 /* login(1) is only called if we execute the login shell */ 1701 if (options.use_login && command != NULL) 1702 options.use_login = 0; 1703 1704#ifdef _UNICOS 1705 cray_setup(pw->pw_uid, pw->pw_name, command); 1706#endif /* _UNICOS */ 1707 1708 /* 1709 * Login(1) does this as well, and it needs uid 0 for the "-h" 1710 * switch, so we let login(1) to this for us. 1711 */ 1712 if (!options.use_login) { 1713#ifdef HAVE_OSF_SIA 1714 session_setup_sia(pw, s->ttyfd == -1 ? NULL : s->tty); 1715 if (!check_quietlogin(s, command)) 1716 do_motd(); 1717#else /* HAVE_OSF_SIA */ 1718 /* When PAM is enabled we rely on it to do the nologin check */ 1719 if (!options.use_pam) 1720 do_nologin(pw); 1721 do_setusercontext(pw); 1722 /* 1723 * PAM session modules in do_setusercontext may have 1724 * generated messages, so if this in an interactive 1725 * login then display them too. 1726 */ 1727 if (!check_quietlogin(s, command)) 1728 display_loginmsg(); 1729#endif /* HAVE_OSF_SIA */ 1730 } 1731 1732#ifdef USE_PAM 1733 if (options.use_pam && !options.use_login && !is_pam_session_open()) { 1734 debug3("PAM session not opened, exiting"); 1735 display_loginmsg(); 1736 exit(254); 1737 } 1738#endif 1739 1740 /* 1741 * Get the shell from the password data. An empty shell field is 1742 * legal, and means /bin/sh. 1743 */ 1744 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; 1745 1746 /* 1747 * Make sure $SHELL points to the shell from the password file, 1748 * even if shell is overridden from login.conf 1749 */ 1750 env = do_setup_env(s, shell); 1751 1752#ifdef HAVE_LOGIN_CAP 1753 shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell); 1754#endif 1755 1756 /* we have to stash the hostname before we close our socket. */ 1757 if (options.use_login) 1758 hostname = get_remote_name_or_ip(utmp_len, 1759 options.use_dns); 1760 /* 1761 * Close the connection descriptors; note that this is the child, and 1762 * the server will still have the socket open, and it is important 1763 * that we do not shutdown it. Note that the descriptors cannot be 1764 * closed before building the environment, as we call 1765 * get_remote_ipaddr there. 1766 */ 1767 child_close_fds(); 1768 1769 /* 1770 * Must take new environment into use so that .ssh/rc, 1771 * /etc/ssh/sshrc and xauth are run in the proper environment. 1772 */ 1773 environ = env; 1774 1775#if defined(KRB5) && defined(USE_AFS) 1776 /* 1777 * At this point, we check to see if AFS is active and if we have 1778 * a valid Kerberos 5 TGT. If so, it seems like a good idea to see 1779 * if we can (and need to) extend the ticket into an AFS token. If 1780 * we don't do this, we run into potential problems if the user's 1781 * home directory is in AFS and it's not world-readable. 1782 */ 1783 1784 if (options.kerberos_get_afs_token && k_hasafs() && 1785 (s->authctxt->krb5_ctx != NULL)) { 1786 char cell[64]; 1787 1788 debug("Getting AFS token"); 1789 1790 k_setpag(); 1791 1792 if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0) 1793 krb5_afslog(s->authctxt->krb5_ctx, 1794 s->authctxt->krb5_fwd_ccache, cell, NULL); 1795 1796 krb5_afslog_home(s->authctxt->krb5_ctx, 1797 s->authctxt->krb5_fwd_ccache, NULL, NULL, pw->pw_dir); 1798 } 1799#endif 1800 1801 /* Change current directory to the user's home directory. */ 1802 if (chdir(pw->pw_dir) < 0) { 1803 /* Suppress missing homedir warning for chroot case */ 1804#ifdef HAVE_LOGIN_CAP 1805 r = login_getcapbool(lc, "requirehome", 0); 1806#endif 1807 if (r || options.chroot_directory == NULL || 1808 strcasecmp(options.chroot_directory, "none") == 0) 1809 fprintf(stderr, "Could not chdir to home " 1810 "directory %s: %s\n", pw->pw_dir, 1811 strerror(errno)); 1812 if (r) 1813 exit(1); 1814 } 1815 1816 closefrom(STDERR_FILENO + 1); 1817 1818 if (!options.use_login) 1819 do_rc_files(s, shell); 1820 1821 /* restore SIGPIPE for child */ 1822 signal(SIGPIPE, SIG_DFL); 1823 1824 if (s->is_subsystem == SUBSYSTEM_INT_SFTP_ERROR) { 1825 printf("This service allows sftp connections only.\n"); 1826 fflush(NULL); 1827 exit(1); 1828 } else if (s->is_subsystem == SUBSYSTEM_INT_SFTP) { 1829 extern int optind, optreset; 1830 int i; 1831 char *p, *args; 1832 1833 setproctitle("%s@%s", s->pw->pw_name, INTERNAL_SFTP_NAME); 1834 args = xstrdup(command ? command : "sftp-server"); 1835 for (i = 0, (p = strtok(args, " ")); p; (p = strtok(NULL, " "))) 1836 if (i < ARGV_MAX - 1) 1837 argv[i++] = p; 1838 argv[i] = NULL; 1839 optind = optreset = 1; 1840 __progname = argv[0]; 1841#ifdef WITH_SELINUX 1842 ssh_selinux_change_context("sftpd_t"); 1843#endif 1844 exit(sftp_server_main(i, argv, s->pw)); 1845 } 1846 1847 fflush(NULL); 1848 1849 if (options.use_login) { 1850 launch_login(pw, hostname); 1851 /* NEVERREACHED */ 1852 } 1853 1854 /* Get the last component of the shell name. */ 1855 if ((shell0 = strrchr(shell, '/')) != NULL) 1856 shell0++; 1857 else 1858 shell0 = shell; 1859 1860 /* 1861 * If we have no command, execute the shell. In this case, the shell 1862 * name to be passed in argv[0] is preceded by '-' to indicate that 1863 * this is a login shell. 1864 */ 1865 if (!command) { 1866 char argv0[256]; 1867 1868 /* Start the shell. Set initial character to '-'. */ 1869 argv0[0] = '-'; 1870 1871 if (strlcpy(argv0 + 1, shell0, sizeof(argv0) - 1) 1872 >= sizeof(argv0) - 1) { 1873 errno = EINVAL; 1874 perror(shell); 1875 exit(1); 1876 } 1877 1878 /* Execute the shell. */ 1879 argv[0] = argv0; 1880 argv[1] = NULL; 1881 execve(shell, argv, env); 1882 1883 /* Executing the shell failed. */ 1884 perror(shell); 1885 exit(1); 1886 } 1887 /* 1888 * Execute the command using the user's shell. This uses the -c 1889 * option to execute the command. 1890 */ 1891 argv[0] = (char *) shell0; 1892 argv[1] = "-c"; 1893 argv[2] = (char *) command; 1894 argv[3] = NULL; 1895 execve(shell, argv, env); 1896 perror(shell); 1897 exit(1); 1898} 1899 1900void 1901session_unused(int id) 1902{ 1903 debug3("%s: session id %d unused", __func__, id); 1904 if (id >= options.max_sessions || 1905 id >= sessions_nalloc) { 1906 fatal("%s: insane session id %d (max %d nalloc %d)", 1907 __func__, id, options.max_sessions, sessions_nalloc); 1908 } 1909 memset(&sessions[id], 0, sizeof(*sessions)); 1910 sessions[id].self = id; 1911 sessions[id].used = 0; 1912 sessions[id].chanid = -1; 1913 sessions[id].ptyfd = -1; 1914 sessions[id].ttyfd = -1; 1915 sessions[id].ptymaster = -1; 1916 sessions[id].x11_chanids = NULL; 1917 sessions[id].next_unused = sessions_first_unused; 1918 sessions_first_unused = id; 1919} 1920 1921Session * 1922session_new(void) 1923{ 1924 Session *s, *tmp; 1925 1926 if (sessions_first_unused == -1) { 1927 if (sessions_nalloc >= options.max_sessions) 1928 return NULL; 1929 debug2("%s: allocate (allocated %d max %d)", 1930 __func__, sessions_nalloc, options.max_sessions); 1931 tmp = xrealloc(sessions, sessions_nalloc + 1, 1932 sizeof(*sessions)); 1933 if (tmp == NULL) { 1934 error("%s: cannot allocate %d sessions", 1935 __func__, sessions_nalloc + 1); 1936 return NULL; 1937 } 1938 sessions = tmp; 1939 session_unused(sessions_nalloc++); 1940 } 1941 1942 if (sessions_first_unused >= sessions_nalloc || 1943 sessions_first_unused < 0) { 1944 fatal("%s: insane first_unused %d max %d nalloc %d", 1945 __func__, sessions_first_unused, options.max_sessions, 1946 sessions_nalloc); 1947 } 1948 1949 s = &sessions[sessions_first_unused]; 1950 if (s->used) { 1951 fatal("%s: session %d already used", 1952 __func__, sessions_first_unused); 1953 } 1954 sessions_first_unused = s->next_unused; 1955 s->used = 1; 1956 s->next_unused = -1; 1957 debug("session_new: session %d", s->self); 1958 1959 return s; 1960} 1961 1962static void 1963session_dump(void) 1964{ 1965 int i; 1966 for (i = 0; i < sessions_nalloc; i++) { 1967 Session *s = &sessions[i]; 1968 1969 debug("dump: used %d next_unused %d session %d %p " 1970 "channel %d pid %ld", 1971 s->used, 1972 s->next_unused, 1973 s->self, 1974 s, 1975 s->chanid, 1976 (long)s->pid); 1977 } 1978} 1979 1980int 1981session_open(Authctxt *authctxt, int chanid) 1982{ 1983 Session *s = session_new(); 1984 debug("session_open: channel %d", chanid); 1985 if (s == NULL) { 1986 error("no more sessions"); 1987 return 0; 1988 } 1989 s->authctxt = authctxt; 1990 s->pw = authctxt->pw; 1991 if (s->pw == NULL || !authctxt->valid) 1992 fatal("no user for session %d", s->self); 1993 debug("session_open: session %d: link with channel %d", s->self, chanid); 1994 s->chanid = chanid; 1995 return 1; 1996} 1997 1998Session * 1999session_by_tty(char *tty) 2000{ 2001 int i; 2002 for (i = 0; i < sessions_nalloc; i++) { 2003 Session *s = &sessions[i]; 2004 if (s->used && s->ttyfd != -1 && strcmp(s->tty, tty) == 0) { 2005 debug("session_by_tty: session %d tty %s", i, tty); 2006 return s; 2007 } 2008 } 2009 debug("session_by_tty: unknown tty %.100s", tty); 2010 session_dump(); 2011 return NULL; 2012} 2013 2014static Session * 2015session_by_channel(int id) 2016{ 2017 int i; 2018 for (i = 0; i < sessions_nalloc; i++) { 2019 Session *s = &sessions[i]; 2020 if (s->used && s->chanid == id) { 2021 debug("session_by_channel: session %d channel %d", 2022 i, id); 2023 return s; 2024 } 2025 } 2026 debug("session_by_channel: unknown channel %d", id); 2027 session_dump(); 2028 return NULL; 2029} 2030 2031static Session * 2032session_by_x11_channel(int id) 2033{ 2034 int i, j; 2035 2036 for (i = 0; i < sessions_nalloc; i++) { 2037 Session *s = &sessions[i]; 2038 2039 if (s->x11_chanids == NULL || !s->used) 2040 continue; 2041 for (j = 0; s->x11_chanids[j] != -1; j++) { 2042 if (s->x11_chanids[j] == id) { 2043 debug("session_by_x11_channel: session %d " 2044 "channel %d", s->self, id); 2045 return s; 2046 } 2047 } 2048 } 2049 debug("session_by_x11_channel: unknown channel %d", id); 2050 session_dump(); 2051 return NULL; 2052} 2053 2054static Session * 2055session_by_pid(pid_t pid) 2056{ 2057 int i; 2058 debug("session_by_pid: pid %ld", (long)pid); 2059 for (i = 0; i < sessions_nalloc; i++) { 2060 Session *s = &sessions[i]; 2061 if (s->used && s->pid == pid) 2062 return s; 2063 } 2064 error("session_by_pid: unknown pid %ld", (long)pid); 2065 session_dump(); 2066 return NULL; 2067} 2068 2069static int 2070session_window_change_req(Session *s) 2071{ 2072 s->col = packet_get_int(); 2073 s->row = packet_get_int(); 2074 s->xpixel = packet_get_int(); 2075 s->ypixel = packet_get_int(); 2076 packet_check_eom(); 2077 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 2078 return 1; 2079} 2080 2081static int 2082session_pty_req(Session *s) 2083{ 2084 u_int len; 2085 int n_bytes; 2086 2087 if (no_pty_flag || !options.permit_tty) { 2088 debug("Allocating a pty not permitted for this authentication."); 2089 return 0; 2090 } 2091 if (s->ttyfd != -1) { 2092 packet_disconnect("Protocol error: you already have a pty."); 2093 return 0; 2094 } 2095 2096 s->term = packet_get_string(&len); 2097 2098 if (compat20) { 2099 s->col = packet_get_int(); 2100 s->row = packet_get_int(); 2101 } else { 2102 s->row = packet_get_int(); 2103 s->col = packet_get_int(); 2104 } 2105 s->xpixel = packet_get_int(); 2106 s->ypixel = packet_get_int(); 2107 2108 if (strcmp(s->term, "") == 0) { 2109 free(s->term); 2110 s->term = NULL; 2111 } 2112 2113 /* Allocate a pty and open it. */ 2114 debug("Allocating pty."); 2115 if (!PRIVSEP(pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, 2116 sizeof(s->tty)))) { 2117 free(s->term); 2118 s->term = NULL; 2119 s->ptyfd = -1; 2120 s->ttyfd = -1; 2121 error("session_pty_req: session %d alloc failed", s->self); 2122 return 0; 2123 } 2124 debug("session_pty_req: session %d alloc %s", s->self, s->tty); 2125 2126 /* for SSH1 the tty modes length is not given */ 2127 if (!compat20) 2128 n_bytes = packet_remaining(); 2129 tty_parse_modes(s->ttyfd, &n_bytes); 2130 2131 if (!use_privsep) 2132 pty_setowner(s->pw, s->tty); 2133 2134 /* Set window size from the packet. */ 2135 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 2136 2137 packet_check_eom(); 2138 session_proctitle(s); 2139 return 1; 2140} 2141 2142static int 2143session_subsystem_req(Session *s) 2144{ 2145 struct stat st; 2146 u_int len; 2147 int success = 0; 2148 char *prog, *cmd; 2149 u_int i; 2150 2151 s->subsys = packet_get_string(&len); 2152 packet_check_eom(); 2153 debug2("subsystem request for %.100s by user %s", s->subsys, 2154 s->pw->pw_name); 2155 2156 for (i = 0; i < options.num_subsystems; i++) { 2157 if (strcmp(s->subsys, options.subsystem_name[i]) == 0) { 2158 prog = options.subsystem_command[i]; 2159 cmd = options.subsystem_args[i]; 2160 if (strcmp(INTERNAL_SFTP_NAME, prog) == 0) { 2161 s->is_subsystem = SUBSYSTEM_INT_SFTP; 2162 debug("subsystem: %s", prog); 2163 } else { 2164 if (stat(prog, &st) < 0) 2165 debug("subsystem: cannot stat %s: %s", 2166 prog, strerror(errno)); 2167 s->is_subsystem = SUBSYSTEM_EXT; 2168 debug("subsystem: exec() %s", cmd); 2169 } 2170 success = do_exec(s, cmd) == 0; 2171 break; 2172 } 2173 } 2174 2175 if (!success) 2176 logit("subsystem request for %.100s by user %s failed, " 2177 "subsystem not found", s->subsys, s->pw->pw_name); 2178 2179 return success; 2180} 2181 2182static int 2183session_x11_req(Session *s) 2184{ 2185 int success; 2186 2187 if (s->auth_proto != NULL || s->auth_data != NULL) { 2188 error("session_x11_req: session %d: " 2189 "x11 forwarding already active", s->self); 2190 return 0; 2191 } 2192 s->single_connection = packet_get_char(); 2193 s->auth_proto = packet_get_string(NULL); 2194 s->auth_data = packet_get_string(NULL); 2195 s->screen = packet_get_int(); 2196 packet_check_eom(); 2197 2198 success = session_setup_x11fwd(s); 2199 if (!success) { 2200 free(s->auth_proto); 2201 free(s->auth_data); 2202 s->auth_proto = NULL; 2203 s->auth_data = NULL; 2204 } 2205 return success; 2206} 2207 2208static int 2209session_shell_req(Session *s) 2210{ 2211 packet_check_eom(); 2212 return do_exec(s, NULL) == 0; 2213} 2214 2215static int 2216session_exec_req(Session *s) 2217{ 2218 u_int len, success; 2219 2220 char *command = packet_get_string(&len); 2221 packet_check_eom(); 2222 success = do_exec(s, command) == 0; 2223 free(command); 2224 return success; 2225} 2226 2227static int 2228session_break_req(Session *s) 2229{ 2230 2231 packet_get_int(); /* ignored */ 2232 packet_check_eom(); 2233 2234 if (s->ptymaster == -1 || tcsendbreak(s->ptymaster, 0) < 0) 2235 return 0; 2236 return 1; 2237} 2238 2239static int 2240session_env_req(Session *s) 2241{ 2242 char *name, *val; 2243 u_int name_len, val_len, i; 2244 2245 name = packet_get_cstring(&name_len); 2246 val = packet_get_cstring(&val_len); 2247 packet_check_eom(); 2248 2249 /* Don't set too many environment variables */ 2250 if (s->num_env > 128) { 2251 debug2("Ignoring env request %s: too many env vars", name); 2252 goto fail; 2253 } 2254 2255 for (i = 0; i < options.num_accept_env; i++) { 2256 if (match_pattern(name, options.accept_env[i])) { 2257 debug2("Setting env %d: %s=%s", s->num_env, name, val); 2258 s->env = xrealloc(s->env, s->num_env + 1, 2259 sizeof(*s->env)); 2260 s->env[s->num_env].name = name; 2261 s->env[s->num_env].val = val; 2262 s->num_env++; 2263 return (1); 2264 } 2265 } 2266 debug2("Ignoring env request %s: disallowed name", name); 2267 2268 fail: 2269 free(name); 2270 free(val); 2271 return (0); 2272} 2273 2274static int 2275session_auth_agent_req(Session *s) 2276{ 2277 static int called = 0; 2278 packet_check_eom(); 2279 if (no_agent_forwarding_flag || !options.allow_agent_forwarding) { 2280 debug("session_auth_agent_req: no_agent_forwarding_flag"); 2281 return 0; 2282 } 2283 if (called) { 2284 return 0; 2285 } else { 2286 called = 1; 2287 return auth_input_request_forwarding(s->pw); 2288 } 2289} 2290 2291int 2292session_input_channel_req(Channel *c, const char *rtype) 2293{ 2294 int success = 0; 2295 Session *s; 2296 2297 if ((s = session_by_channel(c->self)) == NULL) { 2298 logit("session_input_channel_req: no session %d req %.100s", 2299 c->self, rtype); 2300 return 0; 2301 } 2302 debug("session_input_channel_req: session %d req %s", s->self, rtype); 2303 2304 /* 2305 * a session is in LARVAL state until a shell, a command 2306 * or a subsystem is executed 2307 */ 2308 if (c->type == SSH_CHANNEL_LARVAL) { 2309 if (strcmp(rtype, "shell") == 0) { 2310 success = session_shell_req(s); 2311 } else if (strcmp(rtype, "exec") == 0) { 2312 success = session_exec_req(s); 2313 } else if (strcmp(rtype, "pty-req") == 0) { 2314 success = session_pty_req(s); 2315 } else if (strcmp(rtype, "x11-req") == 0) { 2316 success = session_x11_req(s); 2317 } else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) { 2318 success = session_auth_agent_req(s); 2319 } else if (strcmp(rtype, "subsystem") == 0) { 2320 success = session_subsystem_req(s); 2321 } else if (strcmp(rtype, "env") == 0) { 2322 success = session_env_req(s); 2323 } 2324 } 2325 if (strcmp(rtype, "window-change") == 0) { 2326 success = session_window_change_req(s); 2327 } else if (strcmp(rtype, "break") == 0) { 2328 success = session_break_req(s); 2329 } 2330 2331 return success; 2332} 2333 2334void 2335session_set_fds(Session *s, int fdin, int fdout, int fderr, int ignore_fderr, 2336 int is_tty) 2337{ 2338 if (!compat20) 2339 fatal("session_set_fds: called for proto != 2.0"); 2340 /* 2341 * now that have a child and a pipe to the child, 2342 * we can activate our channel and register the fd's 2343 */ 2344 if (s->chanid == -1) 2345 fatal("no channel for session %d", s->self); 2346 channel_set_fds(s->chanid, 2347 fdout, fdin, fderr, 2348 ignore_fderr ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ, 2349 1, is_tty, CHAN_SES_WINDOW_DEFAULT); 2350} 2351 2352/* 2353 * Function to perform pty cleanup. Also called if we get aborted abnormally 2354 * (e.g., due to a dropped connection). 2355 */ 2356void 2357session_pty_cleanup2(Session *s) 2358{ 2359 if (s == NULL) { 2360 error("session_pty_cleanup: no session"); 2361 return; 2362 } 2363 if (s->ttyfd == -1) 2364 return; 2365 2366 debug("session_pty_cleanup: session %d release %s", s->self, s->tty); 2367 2368 /* Record that the user has logged out. */ 2369 if (s->pid != 0) 2370 record_logout(s->pid, s->tty, s->pw->pw_name); 2371 2372 /* Release the pseudo-tty. */ 2373 if (getuid() == 0) 2374 pty_release(s->tty); 2375 2376 /* 2377 * Close the server side of the socket pairs. We must do this after 2378 * the pty cleanup, so that another process doesn't get this pty 2379 * while we're still cleaning up. 2380 */ 2381 if (s->ptymaster != -1 && close(s->ptymaster) < 0) 2382 error("close(s->ptymaster/%d): %s", 2383 s->ptymaster, strerror(errno)); 2384 2385 /* unlink pty from session */ 2386 s->ttyfd = -1; 2387} 2388 2389void 2390session_pty_cleanup(Session *s) 2391{ 2392 PRIVSEP(session_pty_cleanup2(s)); 2393} 2394 2395static char * 2396sig2name(int sig) 2397{ 2398#define SSH_SIG(x) if (sig == SIG ## x) return #x 2399 SSH_SIG(ABRT); 2400 SSH_SIG(ALRM); 2401 SSH_SIG(FPE); 2402 SSH_SIG(HUP); 2403 SSH_SIG(ILL); 2404 SSH_SIG(INT); 2405 SSH_SIG(KILL); 2406 SSH_SIG(PIPE); 2407 SSH_SIG(QUIT); 2408 SSH_SIG(SEGV); 2409 SSH_SIG(TERM); 2410 SSH_SIG(USR1); 2411 SSH_SIG(USR2); 2412#undef SSH_SIG 2413 return "SIG@openssh.com"; 2414} 2415 2416static void 2417session_close_x11(int id) 2418{ 2419 Channel *c; 2420 2421 if ((c = channel_by_id(id)) == NULL) { 2422 debug("session_close_x11: x11 channel %d missing", id); 2423 } else { 2424 /* Detach X11 listener */ 2425 debug("session_close_x11: detach x11 channel %d", id); 2426 channel_cancel_cleanup(id); 2427 if (c->ostate != CHAN_OUTPUT_CLOSED) 2428 chan_mark_dead(c); 2429 } 2430} 2431 2432static void 2433session_close_single_x11(int id, void *arg) 2434{ 2435 Session *s; 2436 u_int i; 2437 2438 debug3("session_close_single_x11: channel %d", id); 2439 channel_cancel_cleanup(id); 2440 if ((s = session_by_x11_channel(id)) == NULL) 2441 fatal("session_close_single_x11: no x11 channel %d", id); 2442 for (i = 0; s->x11_chanids[i] != -1; i++) { 2443 debug("session_close_single_x11: session %d: " 2444 "closing channel %d", s->self, s->x11_chanids[i]); 2445 /* 2446 * The channel "id" is already closing, but make sure we 2447 * close all of its siblings. 2448 */ 2449 if (s->x11_chanids[i] != id) 2450 session_close_x11(s->x11_chanids[i]); 2451 } 2452 free(s->x11_chanids); 2453 s->x11_chanids = NULL; 2454 free(s->display); 2455 s->display = NULL; 2456 free(s->auth_proto); 2457 s->auth_proto = NULL; 2458 free(s->auth_data); 2459 s->auth_data = NULL; 2460 free(s->auth_display); 2461 s->auth_display = NULL; 2462} 2463 2464static void 2465session_exit_message(Session *s, int status) 2466{ 2467 Channel *c; 2468 2469 if ((c = channel_lookup(s->chanid)) == NULL) 2470 fatal("session_exit_message: session %d: no channel %d", 2471 s->self, s->chanid); 2472 debug("session_exit_message: session %d channel %d pid %ld", 2473 s->self, s->chanid, (long)s->pid); 2474 2475 if (WIFEXITED(status)) { 2476 channel_request_start(s->chanid, "exit-status", 0); 2477 packet_put_int(WEXITSTATUS(status)); 2478 packet_send(); 2479 } else if (WIFSIGNALED(status)) { 2480 channel_request_start(s->chanid, "exit-signal", 0); 2481 packet_put_cstring(sig2name(WTERMSIG(status))); 2482#ifdef WCOREDUMP 2483 packet_put_char(WCOREDUMP(status)? 1 : 0); 2484#else /* WCOREDUMP */ 2485 packet_put_char(0); 2486#endif /* WCOREDUMP */ 2487 packet_put_cstring(""); 2488 packet_put_cstring(""); 2489 packet_send(); 2490 } else { 2491 /* Some weird exit cause. Just exit. */ 2492 packet_disconnect("wait returned status %04x.", status); 2493 } 2494 2495 /* disconnect channel */ 2496 debug("session_exit_message: release channel %d", s->chanid); 2497 2498 /* 2499 * Adjust cleanup callback attachment to send close messages when 2500 * the channel gets EOF. The session will be then be closed 2501 * by session_close_by_channel when the childs close their fds. 2502 */ 2503 channel_register_cleanup(c->self, session_close_by_channel, 1); 2504 2505 /* 2506 * emulate a write failure with 'chan_write_failed', nobody will be 2507 * interested in data we write. 2508 * Note that we must not call 'chan_read_failed', since there could 2509 * be some more data waiting in the pipe. 2510 */ 2511 if (c->ostate != CHAN_OUTPUT_CLOSED) 2512 chan_write_failed(c); 2513} 2514 2515void 2516session_close(Session *s) 2517{ 2518 u_int i; 2519 2520 debug("session_close: session %d pid %ld", s->self, (long)s->pid); 2521 if (s->ttyfd != -1) 2522 session_pty_cleanup(s); 2523 free(s->term); 2524 free(s->display); 2525 free(s->x11_chanids); 2526 free(s->auth_display); 2527 free(s->auth_data); 2528 free(s->auth_proto); 2529 free(s->subsys); 2530 if (s->env != NULL) { 2531 for (i = 0; i < s->num_env; i++) { 2532 free(s->env[i].name); 2533 free(s->env[i].val); 2534 } 2535 free(s->env); 2536 } 2537 session_proctitle(s); 2538 session_unused(s->self); 2539} 2540 2541void 2542session_close_by_pid(pid_t pid, int status) 2543{ 2544 Session *s = session_by_pid(pid); 2545 if (s == NULL) { 2546 debug("session_close_by_pid: no session for pid %ld", 2547 (long)pid); 2548 return; 2549 } 2550 if (s->chanid != -1) 2551 session_exit_message(s, status); 2552 if (s->ttyfd != -1) 2553 session_pty_cleanup(s); 2554 s->pid = 0; 2555} 2556 2557/* 2558 * this is called when a channel dies before 2559 * the session 'child' itself dies 2560 */ 2561void 2562session_close_by_channel(int id, void *arg) 2563{ 2564 Session *s = session_by_channel(id); 2565 u_int i; 2566 2567 if (s == NULL) { 2568 debug("session_close_by_channel: no session for id %d", id); 2569 return; 2570 } 2571 debug("session_close_by_channel: channel %d child %ld", 2572 id, (long)s->pid); 2573 if (s->pid != 0) { 2574 debug("session_close_by_channel: channel %d: has child", id); 2575 /* 2576 * delay detach of session, but release pty, since 2577 * the fd's to the child are already closed 2578 */ 2579 if (s->ttyfd != -1) 2580 session_pty_cleanup(s); 2581 return; 2582 } 2583 /* detach by removing callback */ 2584 channel_cancel_cleanup(s->chanid); 2585 2586 /* Close any X11 listeners associated with this session */ 2587 if (s->x11_chanids != NULL) { 2588 for (i = 0; s->x11_chanids[i] != -1; i++) { 2589 session_close_x11(s->x11_chanids[i]); 2590 s->x11_chanids[i] = -1; 2591 } 2592 } 2593 2594 s->chanid = -1; 2595 session_close(s); 2596} 2597 2598void 2599session_destroy_all(void (*closefunc)(Session *)) 2600{ 2601 int i; 2602 for (i = 0; i < sessions_nalloc; i++) { 2603 Session *s = &sessions[i]; 2604 if (s->used) { 2605 if (closefunc != NULL) 2606 closefunc(s); 2607 else 2608 session_close(s); 2609 } 2610 } 2611} 2612 2613static char * 2614session_tty_list(void) 2615{ 2616 static char buf[1024]; 2617 int i; 2618 char *cp; 2619 2620 buf[0] = '\0'; 2621 for (i = 0; i < sessions_nalloc; i++) { 2622 Session *s = &sessions[i]; 2623 if (s->used && s->ttyfd != -1) { 2624 2625 if (strncmp(s->tty, "/dev/", 5) != 0) { 2626 cp = strrchr(s->tty, '/'); 2627 cp = (cp == NULL) ? s->tty : cp + 1; 2628 } else 2629 cp = s->tty + 5; 2630 2631 if (buf[0] != '\0') 2632 strlcat(buf, ",", sizeof buf); 2633 strlcat(buf, cp, sizeof buf); 2634 } 2635 } 2636 if (buf[0] == '\0') 2637 strlcpy(buf, "notty", sizeof buf); 2638 return buf; 2639} 2640 2641void 2642session_proctitle(Session *s) 2643{ 2644 if (s->pw == NULL) 2645 error("no user for session %d", s->self); 2646 else 2647 setproctitle("%s@%s", s->pw->pw_name, session_tty_list()); 2648} 2649 2650int 2651session_setup_x11fwd(Session *s) 2652{ 2653 struct stat st; 2654 char display[512], auth_display[512]; 2655 char hostname[MAXHOSTNAMELEN]; 2656 u_int i; 2657 2658 if (no_x11_forwarding_flag) { 2659 packet_send_debug("X11 forwarding disabled in user configuration file."); 2660 return 0; 2661 } 2662 if (!options.x11_forwarding) { 2663 debug("X11 forwarding disabled in server configuration file."); 2664 return 0; 2665 } 2666 if (!options.xauth_location || 2667 (stat(options.xauth_location, &st) == -1)) { 2668 packet_send_debug("No xauth program; cannot forward with spoofing."); 2669 return 0; 2670 } 2671 if (options.use_login) { 2672 packet_send_debug("X11 forwarding disabled; " 2673 "not compatible with UseLogin=yes."); 2674 return 0; 2675 } 2676 if (s->display != NULL) { 2677 debug("X11 display already set."); 2678 return 0; 2679 } 2680 if (x11_create_display_inet(options.x11_display_offset, 2681 options.x11_use_localhost, s->single_connection, 2682 &s->display_number, &s->x11_chanids) == -1) { 2683 debug("x11_create_display_inet failed."); 2684 return 0; 2685 } 2686 for (i = 0; s->x11_chanids[i] != -1; i++) { 2687 channel_register_cleanup(s->x11_chanids[i], 2688 session_close_single_x11, 0); 2689 } 2690 2691 /* Set up a suitable value for the DISPLAY variable. */ 2692 if (gethostname(hostname, sizeof(hostname)) < 0) 2693 fatal("gethostname: %.100s", strerror(errno)); 2694 /* 2695 * auth_display must be used as the displayname when the 2696 * authorization entry is added with xauth(1). This will be 2697 * different than the DISPLAY string for localhost displays. 2698 */ 2699 if (options.x11_use_localhost) { 2700 snprintf(display, sizeof display, "localhost:%u.%u", 2701 s->display_number, s->screen); 2702 snprintf(auth_display, sizeof auth_display, "unix:%u.%u", 2703 s->display_number, s->screen); 2704 s->display = xstrdup(display); 2705 s->auth_display = xstrdup(auth_display); 2706 } else { 2707#ifdef IPADDR_IN_DISPLAY 2708 struct hostent *he; 2709 struct in_addr my_addr; 2710 2711 he = gethostbyname(hostname); 2712 if (he == NULL) { 2713 error("Can't get IP address for X11 DISPLAY."); 2714 packet_send_debug("Can't get IP address for X11 DISPLAY."); 2715 return 0; 2716 } 2717 memcpy(&my_addr, he->h_addr_list[0], sizeof(struct in_addr)); 2718 snprintf(display, sizeof display, "%.50s:%u.%u", inet_ntoa(my_addr), 2719 s->display_number, s->screen); 2720#else 2721 snprintf(display, sizeof display, "%.400s:%u.%u", hostname, 2722 s->display_number, s->screen); 2723#endif 2724 s->display = xstrdup(display); 2725 s->auth_display = xstrdup(display); 2726 } 2727 2728 return 1; 2729} 2730 2731static void 2732do_authenticated2(Authctxt *authctxt) 2733{ 2734 server_loop2(authctxt); 2735} 2736 2737void 2738do_cleanup(Authctxt *authctxt) 2739{ 2740 static int called = 0; 2741 2742 debug("do_cleanup"); 2743 2744 /* no cleanup if we're in the child for login shell */ 2745 if (is_child) 2746 return; 2747 2748 /* avoid double cleanup */ 2749 if (called) 2750 return; 2751 called = 1; 2752 2753 if (authctxt == NULL) 2754 return; 2755 2756#ifdef USE_PAM 2757 if (options.use_pam) { 2758 sshpam_cleanup(); 2759 sshpam_thread_cleanup(); 2760 } 2761#endif 2762 2763 if (!authctxt->authenticated) 2764 return; 2765 2766#ifdef KRB5 2767 if (options.kerberos_ticket_cleanup && 2768 authctxt->krb5_ctx) 2769 krb5_cleanup_proc(authctxt); 2770#endif 2771 2772#ifdef GSSAPI 2773 if (compat20 && options.gss_cleanup_creds) 2774 ssh_gssapi_cleanup_creds(); 2775#endif 2776 2777 /* remove agent socket */ 2778 auth_sock_cleanup_proc(authctxt->pw); 2779 2780 /* 2781 * Cleanup ptys/utmp only if privsep is disabled, 2782 * or if running in monitor. 2783 */ 2784 if (!use_privsep || mm_is_monitor()) 2785 session_destroy_all(session_pty_cleanup2); 2786} 2787