1 /* $NetBSD: session.c,v 1.20 2016/08/02 13:45:12 christos Exp $ */ 2 /* $OpenBSD: session.c,v 1.282 2016/03/10 11:47:57 djm Exp $ */ 3 /* 4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 5 * All rights reserved 6 * 7 * As far as I am concerned, the code I have written for this software 8 * can be used freely for any purpose. Any derived versions of this 9 * software must be clearly marked as such, and if the derived work is 10 * incompatible with the protocol description in the RFC file, it must be 11 * called by a name other than "ssh" or "Secure Shell". 12 * 13 * SSH2 support by Markus Friedl. 14 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 15 * 16 * Redistribution and use in source and binary forms, with or without 17 * modification, are permitted provided that the following conditions 18 * are met: 19 * 1. Redistributions of source code must retain the above copyright 20 * notice, this list of conditions and the following disclaimer. 21 * 2. Redistributions in binary form must reproduce the above copyright 22 * notice, this list of conditions and the following disclaimer in the 23 * documentation and/or other materials provided with the distribution. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 26 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 27 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 28 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 29 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 30 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 31 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 32 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 33 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 34 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 35 */ 36 37 #include "includes.h" 38 __RCSID("$NetBSD: session.c,v 1.20 2016/08/02 13:45:12 christos Exp $"); 39 #include <sys/types.h> 40 #include <sys/wait.h> 41 #include <sys/un.h> 42 #include <sys/stat.h> 43 #include <sys/socket.h> 44 #include <sys/queue.h> 45 46 #include <ctype.h> 47 #include <errno.h> 48 #include <fcntl.h> 49 #include <grp.h> 50 #include <login_cap.h> 51 #include <netdb.h> 52 #include <paths.h> 53 #include <pwd.h> 54 #include <signal.h> 55 #include <stdio.h> 56 #include <stdlib.h> 57 #include <string.h> 58 #include <unistd.h> 59 #include <limits.h> 60 61 #include "xmalloc.h" 62 #include "ssh.h" 63 #include "ssh1.h" 64 #include "ssh2.h" 65 #include "sshpty.h" 66 #include "packet.h" 67 #include "buffer.h" 68 #include "match.h" 69 #include "uidswap.h" 70 #include "compat.h" 71 #include "channels.h" 72 #include "key.h" 73 #include "cipher.h" 74 #include "kex.h" 75 #include "hostfile.h" 76 #include "auth.h" 77 #include "auth-options.h" 78 #include "authfd.h" 79 #include "pathnames.h" 80 #include "log.h" 81 #include "misc.h" 82 #include "servconf.h" 83 #include "sshlogin.h" 84 #include "serverloop.h" 85 #include "canohost.h" 86 #include "session.h" 87 #ifdef GSSAPI 88 #include "ssh-gss.h" 89 #endif 90 #include "monitor_wrap.h" 91 #include "sftp.h" 92 93 #ifdef KRB5 94 #include <krb5/kafs.h> 95 #endif 96 97 #define IS_INTERNAL_SFTP(c) \ 98 (!strncmp(c, INTERNAL_SFTP_NAME, sizeof(INTERNAL_SFTP_NAME) - 1) && \ 99 (c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\0' || \ 100 c[sizeof(INTERNAL_SFTP_NAME) - 1] == ' ' || \ 101 c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\t')) 102 103 /* func */ 104 105 Session *session_new(void); 106 void session_set_fds(Session *, int, int, int, int, int); 107 void session_pty_cleanup(Session *); 108 void session_proctitle(Session *); 109 int session_setup_x11fwd(Session *); 110 int do_exec_pty(Session *, const char *); 111 int do_exec_no_pty(Session *, const char *); 112 int do_exec(Session *, const char *); 113 void do_login(Session *, const char *); 114 __dead void do_child(Session *, const char *); 115 void do_motd(void); 116 int check_quietlogin(Session *, const char *); 117 118 static void do_authenticated1(Authctxt *); 119 static void do_authenticated2(Authctxt *); 120 121 static int session_pty_req(Session *); 122 123 /* import */ 124 extern ServerOptions options; 125 extern char *__progname; 126 extern int log_stderr; 127 extern int debug_flag; 128 extern u_int utmp_len; 129 extern int startup_pipe; 130 extern void destroy_sensitive_data(void); 131 extern Buffer loginmsg; 132 133 /* original command from peer. */ 134 const char *original_command = NULL; 135 136 /* data */ 137 static int sessions_first_unused = -1; 138 static int sessions_nalloc = 0; 139 static Session *sessions = NULL; 140 141 #define SUBSYSTEM_NONE 0 142 #define SUBSYSTEM_EXT 1 143 #define SUBSYSTEM_INT_SFTP 2 144 #define SUBSYSTEM_INT_SFTP_ERROR 3 145 146 #ifdef HAVE_LOGIN_CAP 147 login_cap_t *lc; 148 #endif 149 150 static int is_child = 0; 151 static int in_chroot = 0; 152 153 /* Name and directory of socket for authentication agent forwarding. */ 154 static char *auth_sock_name = NULL; 155 static char *auth_sock_dir = NULL; 156 157 /* removes the agent forwarding socket */ 158 159 static void 160 auth_sock_cleanup_proc(struct passwd *pw) 161 { 162 if (auth_sock_name != NULL) { 163 temporarily_use_uid(pw); 164 unlink(auth_sock_name); 165 rmdir(auth_sock_dir); 166 auth_sock_name = NULL; 167 restore_uid(); 168 } 169 } 170 171 static int 172 auth_input_request_forwarding(struct passwd * pw) 173 { 174 Channel *nc; 175 int sock = -1; 176 177 if (auth_sock_name != NULL) { 178 error("authentication forwarding requested twice."); 179 return 0; 180 } 181 182 /* Temporarily drop privileged uid for mkdir/bind. */ 183 temporarily_use_uid(pw); 184 185 /* Allocate a buffer for the socket name, and format the name. */ 186 auth_sock_dir = xstrdup("/tmp/ssh-XXXXXXXXXX"); 187 188 /* Create private directory for socket */ 189 if (mkdtemp(auth_sock_dir) == NULL) { 190 packet_send_debug("Agent forwarding disabled: " 191 "mkdtemp() failed: %.100s", strerror(errno)); 192 restore_uid(); 193 free(auth_sock_dir); 194 auth_sock_dir = NULL; 195 goto authsock_err; 196 } 197 198 xasprintf(&auth_sock_name, "%s/agent.%ld", 199 auth_sock_dir, (long) getpid()); 200 201 /* Start a Unix listener on auth_sock_name. */ 202 sock = unix_listener(auth_sock_name, SSH_LISTEN_BACKLOG, 0); 203 204 /* Restore the privileged uid. */ 205 restore_uid(); 206 207 /* Check for socket/bind/listen failure. */ 208 if (sock < 0) 209 goto authsock_err; 210 211 /* Allocate a channel for the authentication agent socket. */ 212 /* this shouldn't matter if its hpn or not - cjr */ 213 nc = channel_new("auth socket", 214 SSH_CHANNEL_AUTH_SOCKET, sock, sock, -1, 215 CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 216 0, "auth socket", 1); 217 nc->path = xstrdup(auth_sock_name); 218 return 1; 219 220 authsock_err: 221 free(auth_sock_name); 222 if (auth_sock_dir != NULL) { 223 rmdir(auth_sock_dir); 224 free(auth_sock_dir); 225 } 226 if (sock != -1) 227 close(sock); 228 auth_sock_name = NULL; 229 auth_sock_dir = NULL; 230 return 0; 231 } 232 233 static void 234 display_loginmsg(void) 235 { 236 if (buffer_len(&loginmsg) > 0) { 237 buffer_append(&loginmsg, "\0", 1); 238 printf("%s", (char *)buffer_ptr(&loginmsg)); 239 buffer_clear(&loginmsg); 240 } 241 } 242 243 void 244 do_authenticated(Authctxt *authctxt) 245 { 246 setproctitle("%s", authctxt->pw->pw_name); 247 248 /* setup the channel layer */ 249 /* XXX - streamlocal? */ 250 if (no_port_forwarding_flag || 251 (options.allow_tcp_forwarding & FORWARD_LOCAL) == 0) 252 channel_disable_adm_local_opens(); 253 else 254 channel_permit_all_opens(); 255 256 auth_debug_send(); 257 258 if (compat20) 259 do_authenticated2(authctxt); 260 else 261 do_authenticated1(authctxt); 262 263 do_cleanup(authctxt); 264 } 265 266 /* Check untrusted xauth strings for metacharacters */ 267 static int 268 xauth_valid_string(const char *s) 269 { 270 size_t i; 271 272 for (i = 0; s[i] != '\0'; i++) { 273 if (!isalnum((u_char)s[i]) && 274 s[i] != '.' && s[i] != ':' && s[i] != '/' && 275 s[i] != '-' && s[i] != '_') 276 return 0; 277 } 278 return 1; 279 } 280 281 /* 282 * Prepares for an interactive session. This is called after the user has 283 * been successfully authenticated. During this message exchange, pseudo 284 * terminals are allocated, X11, TCP/IP, and authentication agent forwardings 285 * are requested, etc. 286 */ 287 static void 288 do_authenticated1(Authctxt *authctxt) 289 { 290 Session *s; 291 char *command; 292 int success, type, screen_flag; 293 int enable_compression_after_reply = 0; 294 u_int proto_len, data_len, dlen, compression_level = 0; 295 296 s = session_new(); 297 if (s == NULL) { 298 error("no more sessions"); 299 return; 300 } 301 s->authctxt = authctxt; 302 s->pw = authctxt->pw; 303 304 /* 305 * We stay in this loop until the client requests to execute a shell 306 * or a command. 307 */ 308 for (;;) { 309 success = 0; 310 311 /* Get a packet from the client. */ 312 type = packet_read(); 313 314 /* Process the packet. */ 315 switch (type) { 316 case SSH_CMSG_REQUEST_COMPRESSION: 317 compression_level = packet_get_int(); 318 packet_check_eom(); 319 if (compression_level < 1 || compression_level > 9) { 320 packet_send_debug("Received invalid compression level %d.", 321 compression_level); 322 break; 323 } 324 if (options.compression == COMP_NONE) { 325 debug2("compression disabled"); 326 break; 327 } 328 /* Enable compression after we have responded with SUCCESS. */ 329 enable_compression_after_reply = 1; 330 success = 1; 331 break; 332 333 case SSH_CMSG_REQUEST_PTY: 334 success = session_pty_req(s); 335 break; 336 337 case SSH_CMSG_X11_REQUEST_FORWARDING: 338 s->auth_proto = packet_get_string(&proto_len); 339 s->auth_data = packet_get_string(&data_len); 340 341 screen_flag = packet_get_protocol_flags() & 342 SSH_PROTOFLAG_SCREEN_NUMBER; 343 debug2("SSH_PROTOFLAG_SCREEN_NUMBER: %d", screen_flag); 344 345 if (packet_remaining() == 4) { 346 if (!screen_flag) 347 debug2("Buggy client: " 348 "X11 screen flag missing"); 349 s->screen = packet_get_int(); 350 } else { 351 s->screen = 0; 352 } 353 packet_check_eom(); 354 if (xauth_valid_string(s->auth_proto) && 355 xauth_valid_string(s->auth_data)) 356 success = session_setup_x11fwd(s); 357 else { 358 success = 0; 359 error("Invalid X11 forwarding data"); 360 } 361 if (!success) { 362 free(s->auth_proto); 363 free(s->auth_data); 364 s->auth_proto = NULL; 365 s->auth_data = NULL; 366 } 367 break; 368 369 case SSH_CMSG_AGENT_REQUEST_FORWARDING: 370 if (!options.allow_agent_forwarding || 371 no_agent_forwarding_flag || compat13) { 372 debug("Authentication agent forwarding not permitted for this authentication."); 373 break; 374 } 375 debug("Received authentication agent forwarding request."); 376 success = auth_input_request_forwarding(s->pw); 377 break; 378 379 case SSH_CMSG_PORT_FORWARD_REQUEST: 380 if (no_port_forwarding_flag) { 381 debug("Port forwarding not permitted for this authentication."); 382 break; 383 } 384 if (!(options.allow_tcp_forwarding & FORWARD_REMOTE)) { 385 debug("Port forwarding not permitted."); 386 break; 387 } 388 debug("Received TCP/IP port forwarding request."); 389 if (channel_input_port_forward_request(s->pw->pw_uid == 0, 390 &options.fwd_opts) < 0) { 391 debug("Port forwarding failed."); 392 break; 393 } 394 success = 1; 395 break; 396 397 case SSH_CMSG_MAX_PACKET_SIZE: 398 if (packet_set_maxsize(packet_get_int()) > 0) 399 success = 1; 400 break; 401 402 #if defined(AFS) || defined(KRB5) 403 case SSH_CMSG_HAVE_KERBEROS_TGT: 404 if (!options.kerberos_tgt_passing) { 405 verbose("Kerberos TGT passing disabled."); 406 } else { 407 char *kdata = packet_get_string(&dlen); 408 packet_check_eom(); 409 410 /* XXX - 0x41, see creds_to_radix version */ 411 if (kdata[0] != 0x41) { 412 #ifdef KRB5 413 krb5_data tgt; 414 tgt.data = kdata; 415 tgt.length = dlen; 416 417 if (auth_krb5_tgt(s->authctxt, &tgt)) 418 success = 1; 419 else 420 verbose("Kerberos v5 TGT refused for %.100s", s->authctxt->user); 421 #endif /* KRB5 */ 422 } else { 423 #ifdef AFS 424 if (auth_krb4_tgt(s->authctxt, kdata)) 425 success = 1; 426 else 427 verbose("Kerberos v4 TGT refused for %.100s", s->authctxt->user); 428 #endif /* AFS */ 429 } 430 free(kdata); 431 } 432 break; 433 #endif /* AFS || KRB5 */ 434 435 #ifdef AFS 436 case SSH_CMSG_HAVE_AFS_TOKEN: 437 if (!options.afs_token_passing || !k_hasafs()) { 438 verbose("AFS token passing disabled."); 439 } else { 440 /* Accept AFS token. */ 441 char *token = packet_get_string(&dlen); 442 packet_check_eom(); 443 444 if (auth_afs_token(s->authctxt, token)) 445 success = 1; 446 else 447 verbose("AFS token refused for %.100s", 448 s->authctxt->user); 449 free(token); 450 } 451 break; 452 #endif /* AFS */ 453 454 case SSH_CMSG_EXEC_SHELL: 455 case SSH_CMSG_EXEC_CMD: 456 if (type == SSH_CMSG_EXEC_CMD) { 457 command = packet_get_string(&dlen); 458 debug("Exec command '%.500s'", command); 459 if (do_exec(s, command) != 0) 460 packet_disconnect( 461 "command execution failed"); 462 free(command); 463 } else { 464 if (do_exec(s, NULL) != 0) 465 packet_disconnect( 466 "shell execution failed"); 467 } 468 packet_check_eom(); 469 session_close(s); 470 return; 471 472 default: 473 /* 474 * Any unknown messages in this phase are ignored, 475 * and a failure message is returned. 476 */ 477 logit("Unknown packet type received after authentication: %d", type); 478 } 479 packet_start(success ? SSH_SMSG_SUCCESS : SSH_SMSG_FAILURE); 480 packet_send(); 481 packet_write_wait(); 482 483 /* Enable compression now that we have replied if appropriate. */ 484 if (enable_compression_after_reply) { 485 enable_compression_after_reply = 0; 486 packet_start_compression(compression_level); 487 } 488 } 489 } 490 491 #define USE_PIPES 1 492 /* 493 * This is called to fork and execute a command when we have no tty. This 494 * will call do_child from the child, and server_loop from the parent after 495 * setting up file descriptors and such. 496 */ 497 int 498 do_exec_no_pty(Session *s, const char *command) 499 { 500 pid_t pid; 501 #ifdef USE_PIPES 502 int pin[2], pout[2], perr[2]; 503 504 if (s == NULL) 505 fatal("do_exec_no_pty: no session"); 506 507 /* Allocate pipes for communicating with the program. */ 508 if (pipe(pin) < 0) { 509 error("%s: pipe in: %.100s", __func__, strerror(errno)); 510 return -1; 511 } 512 if (pipe(pout) < 0) { 513 error("%s: pipe out: %.100s", __func__, strerror(errno)); 514 close(pin[0]); 515 close(pin[1]); 516 return -1; 517 } 518 if (pipe(perr) < 0) { 519 error("%s: pipe err: %.100s", __func__, 520 strerror(errno)); 521 close(pin[0]); 522 close(pin[1]); 523 close(pout[0]); 524 close(pout[1]); 525 return -1; 526 } 527 #else 528 int inout[2], err[2]; 529 530 if (s == NULL) 531 fatal("do_exec_no_pty: no session"); 532 533 /* Uses socket pairs to communicate with the program. */ 534 if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) < 0) { 535 error("%s: socketpair #1: %.100s", __func__, strerror(errno)); 536 return -1; 537 } 538 if (socketpair(AF_UNIX, SOCK_STREAM, 0, err) < 0) { 539 error("%s: socketpair #2: %.100s", __func__, 540 strerror(errno)); 541 close(inout[0]); 542 close(inout[1]); 543 return -1; 544 } 545 #endif 546 547 session_proctitle(s); 548 549 #ifdef notdef 550 #if defined(USE_PAM) 551 if (options.use_pam && !use_privsep) 552 do_pam_setcred(1); 553 #endif /* USE_PAM */ 554 #endif 555 556 /* Fork the child. */ 557 switch ((pid = fork())) { 558 case -1: 559 error("%s: fork: %.100s", __func__, strerror(errno)); 560 #ifdef USE_PIPES 561 close(pin[0]); 562 close(pin[1]); 563 close(pout[0]); 564 close(pout[1]); 565 close(perr[0]); 566 close(perr[1]); 567 #else 568 close(inout[0]); 569 close(inout[1]); 570 close(err[0]); 571 close(err[1]); 572 #endif 573 return -1; 574 case 0: 575 is_child = 1; 576 577 /* Child. Reinitialize the log since the pid has changed. */ 578 log_init(__progname, options.log_level, 579 options.log_facility, log_stderr); 580 581 /* 582 * Create a new session and process group since the 4.4BSD 583 * setlogin() affects the entire process group. 584 */ 585 if (setsid() < 0) 586 error("setsid failed: %.100s", strerror(errno)); 587 588 #ifdef USE_PIPES 589 /* 590 * Redirect stdin. We close the parent side of the socket 591 * pair, and make the child side the standard input. 592 */ 593 close(pin[1]); 594 if (dup2(pin[0], 0) < 0) 595 perror("dup2 stdin"); 596 close(pin[0]); 597 598 /* Redirect stdout. */ 599 close(pout[0]); 600 if (dup2(pout[1], 1) < 0) 601 perror("dup2 stdout"); 602 close(pout[1]); 603 604 /* Redirect stderr. */ 605 close(perr[0]); 606 if (dup2(perr[1], 2) < 0) 607 perror("dup2 stderr"); 608 close(perr[1]); 609 #else 610 /* 611 * Redirect stdin, stdout, and stderr. Stdin and stdout will 612 * use the same socket, as some programs (particularly rdist) 613 * seem to depend on it. 614 */ 615 close(inout[1]); 616 close(err[1]); 617 if (dup2(inout[0], 0) < 0) /* stdin */ 618 perror("dup2 stdin"); 619 if (dup2(inout[0], 1) < 0) /* stdout (same as stdin) */ 620 perror("dup2 stdout"); 621 close(inout[0]); 622 if (dup2(err[0], 2) < 0) /* stderr */ 623 perror("dup2 stderr"); 624 close(err[0]); 625 #endif 626 627 /* Do processing for the child (exec command etc). */ 628 do_child(s, command); 629 /* NOTREACHED */ 630 default: 631 break; 632 } 633 634 s->pid = pid; 635 /* Set interactive/non-interactive mode. */ 636 packet_set_interactive(s->display != NULL, 637 options.ip_qos_interactive, options.ip_qos_bulk); 638 639 #ifdef USE_PIPES 640 /* We are the parent. Close the child sides of the pipes. */ 641 close(pin[0]); 642 close(pout[1]); 643 close(perr[1]); 644 645 if (compat20) { 646 session_set_fds(s, pin[1], pout[0], perr[0], 647 s->is_subsystem, 0); 648 } else { 649 /* Enter the interactive session. */ 650 server_loop(pid, pin[1], pout[0], perr[0]); 651 /* server_loop has closed pin[1], pout[0], and perr[0]. */ 652 } 653 #else 654 /* We are the parent. Close the child sides of the socket pairs. */ 655 close(inout[0]); 656 close(err[0]); 657 658 /* 659 * Enter the interactive session. Note: server_loop must be able to 660 * handle the case that fdin and fdout are the same. 661 */ 662 if (compat20) { 663 session_set_fds(s, inout[1], inout[1], err[1], 664 s->is_subsystem, 0); 665 } else { 666 server_loop(pid, inout[1], inout[1], err[1]); 667 /* server_loop has closed inout[1] and err[1]. */ 668 } 669 #endif 670 return 0; 671 } 672 673 /* 674 * This is called to fork and execute a command when we have a tty. This 675 * will call do_child from the child, and server_loop from the parent after 676 * setting up file descriptors, controlling tty, updating wtmp, utmp, 677 * lastlog, and other such operations. 678 */ 679 int 680 do_exec_pty(Session *s, const char *command) 681 { 682 int fdout, ptyfd, ttyfd, ptymaster; 683 pid_t pid; 684 685 if (s == NULL) 686 fatal("do_exec_pty: no session"); 687 ptyfd = s->ptyfd; 688 ttyfd = s->ttyfd; 689 690 #if defined(USE_PAM) 691 if (options.use_pam) { 692 do_pam_set_tty(s->tty); 693 if (!use_privsep) 694 do_pam_setcred(1); 695 } 696 #endif 697 698 /* 699 * Create another descriptor of the pty master side for use as the 700 * standard input. We could use the original descriptor, but this 701 * simplifies code in server_loop. The descriptor is bidirectional. 702 * Do this before forking (and cleanup in the child) so as to 703 * detect and gracefully fail out-of-fd conditions. 704 */ 705 if ((fdout = dup(ptyfd)) < 0) { 706 error("%s: dup #1: %s", __func__, strerror(errno)); 707 close(ttyfd); 708 close(ptyfd); 709 return -1; 710 } 711 /* we keep a reference to the pty master */ 712 if ((ptymaster = dup(ptyfd)) < 0) { 713 error("%s: dup #2: %s", __func__, strerror(errno)); 714 close(ttyfd); 715 close(ptyfd); 716 close(fdout); 717 return -1; 718 } 719 720 /* Fork the child. */ 721 switch ((pid = fork())) { 722 case -1: 723 error("%s: fork: %.100s", __func__, strerror(errno)); 724 close(fdout); 725 close(ptymaster); 726 close(ttyfd); 727 close(ptyfd); 728 return -1; 729 case 0: 730 is_child = 1; 731 732 close(fdout); 733 close(ptymaster); 734 735 /* Child. Reinitialize the log because the pid has changed. */ 736 log_init(__progname, options.log_level, 737 options.log_facility, log_stderr); 738 /* Close the master side of the pseudo tty. */ 739 close(ptyfd); 740 741 /* Make the pseudo tty our controlling tty. */ 742 pty_make_controlling_tty(&ttyfd, s->tty); 743 744 /* Redirect stdin/stdout/stderr from the pseudo tty. */ 745 if (dup2(ttyfd, 0) < 0) 746 error("dup2 stdin: %s", strerror(errno)); 747 if (dup2(ttyfd, 1) < 0) 748 error("dup2 stdout: %s", strerror(errno)); 749 if (dup2(ttyfd, 2) < 0) 750 error("dup2 stderr: %s", strerror(errno)); 751 752 /* Close the extra descriptor for the pseudo tty. */ 753 close(ttyfd); 754 755 /* record login, etc. similar to login(1) */ 756 if (!(options.use_login && command == NULL)) 757 do_login(s, command); 758 759 /* 760 * Do common processing for the child, such as execing 761 * the command. 762 */ 763 do_child(s, command); 764 /* NOTREACHED */ 765 default: 766 break; 767 } 768 s->pid = pid; 769 770 /* Parent. Close the slave side of the pseudo tty. */ 771 close(ttyfd); 772 773 /* Enter interactive session. */ 774 s->ptymaster = ptymaster; 775 packet_set_interactive(1, 776 options.ip_qos_interactive, options.ip_qos_bulk); 777 if (compat20) { 778 session_set_fds(s, ptyfd, fdout, -1, 1, 1); 779 } else { 780 server_loop(pid, ptyfd, fdout, -1); 781 /* server_loop _has_ closed ptyfd and fdout. */ 782 } 783 return 0; 784 } 785 786 /* 787 * This is called to fork and execute a command. If another command is 788 * to be forced, execute that instead. 789 */ 790 int 791 do_exec(Session *s, const char *command) 792 { 793 struct ssh *ssh = active_state; /* XXX */ 794 int ret; 795 const char *forced = NULL, *tty = NULL; 796 char session_type[1024]; 797 798 if (options.adm_forced_command) { 799 original_command = command; 800 command = options.adm_forced_command; 801 forced = "(config)"; 802 } else if (forced_command) { 803 original_command = command; 804 command = forced_command; 805 forced = "(key-option)"; 806 } 807 if (forced != NULL) { 808 if (IS_INTERNAL_SFTP(command)) { 809 s->is_subsystem = s->is_subsystem ? 810 SUBSYSTEM_INT_SFTP : SUBSYSTEM_INT_SFTP_ERROR; 811 } else if (s->is_subsystem) 812 s->is_subsystem = SUBSYSTEM_EXT; 813 snprintf(session_type, sizeof(session_type), 814 "forced-command %s '%.900s'", forced, command); 815 } else if (s->is_subsystem) { 816 snprintf(session_type, sizeof(session_type), 817 "subsystem '%.900s'", s->subsys); 818 } else if (command == NULL) { 819 snprintf(session_type, sizeof(session_type), "shell"); 820 } else { 821 /* NB. we don't log unforced commands to preserve privacy */ 822 snprintf(session_type, sizeof(session_type), "command"); 823 } 824 825 if (s->ttyfd != -1) { 826 tty = s->tty; 827 if (strncmp(tty, "/dev/", 5) == 0) 828 tty += 5; 829 } 830 831 verbose("Starting session: %s%s%s for %s from %.200s port %d id %d", 832 session_type, 833 tty == NULL ? "" : " on ", 834 tty == NULL ? "" : tty, 835 s->pw->pw_name, 836 ssh_remote_ipaddr(ssh), 837 ssh_remote_port(ssh), 838 s->self); 839 840 #ifdef GSSAPI 841 if (options.gss_authentication) { 842 temporarily_use_uid(s->pw); 843 ssh_gssapi_storecreds(); 844 restore_uid(); 845 } 846 #endif 847 if (s->ttyfd != -1) 848 ret = do_exec_pty(s, command); 849 else 850 ret = do_exec_no_pty(s, command); 851 852 original_command = NULL; 853 854 /* 855 * Clear loginmsg: it's the child's responsibility to display 856 * it to the user, otherwise multiple sessions may accumulate 857 * multiple copies of the login messages. 858 */ 859 buffer_clear(&loginmsg); 860 861 return ret; 862 } 863 864 865 /* administrative, login(1)-like work */ 866 void 867 do_login(Session *s, const char *command) 868 { 869 struct ssh *ssh = active_state; /* XXX */ 870 socklen_t fromlen; 871 struct sockaddr_storage from; 872 struct passwd * pw = s->pw; 873 pid_t pid = getpid(); 874 875 /* 876 * Get IP address of client. If the connection is not a socket, let 877 * the address be 0.0.0.0. 878 */ 879 memset(&from, 0, sizeof(from)); 880 fromlen = sizeof(from); 881 if (packet_connection_is_on_socket()) { 882 if (getpeername(packet_get_connection_in(), 883 (struct sockaddr *)&from, &fromlen) < 0) { 884 debug("getpeername: %.100s", strerror(errno)); 885 cleanup_exit(255); 886 } 887 } 888 889 /* Record that there was a login on that tty from the remote host. */ 890 if (!use_privsep) 891 record_login(pid, s->tty, pw->pw_name, pw->pw_uid, 892 session_get_remote_name_or_ip(ssh, utmp_len, 893 options.use_dns), 894 (struct sockaddr *)&from, fromlen); 895 896 #ifdef USE_PAM 897 /* 898 * If password change is needed, do it now. 899 * This needs to occur before the ~/.hushlogin check. 900 */ 901 if (options.use_pam && !use_privsep && s->authctxt->force_pwchange) { 902 display_loginmsg(); 903 do_pam_chauthtok(); 904 s->authctxt->force_pwchange = 0; 905 /* XXX - signal [net] parent to enable forwardings */ 906 } 907 #endif 908 909 if (check_quietlogin(s, command)) 910 return; 911 912 display_loginmsg(); 913 914 do_motd(); 915 } 916 917 /* 918 * Display the message of the day. 919 */ 920 void 921 do_motd(void) 922 { 923 FILE *f; 924 char buf[256]; 925 926 if (options.print_motd) { 927 #ifdef HAVE_LOGIN_CAP 928 f = fopen(login_getcapstr(lc, "welcome", __UNCONST("/etc/motd"), 929 __UNCONST("/etc/motd")), "r"); 930 #else 931 f = fopen("/etc/motd", "r"); 932 #endif 933 if (f) { 934 while (fgets(buf, sizeof(buf), f)) 935 fputs(buf, stdout); 936 fclose(f); 937 } 938 } 939 } 940 941 942 /* 943 * Check for quiet login, either .hushlogin or command given. 944 */ 945 int 946 check_quietlogin(Session *s, const char *command) 947 { 948 char buf[256]; 949 struct passwd *pw = s->pw; 950 struct stat st; 951 952 /* Return 1 if .hushlogin exists or a command given. */ 953 if (command != NULL) 954 return 1; 955 snprintf(buf, sizeof(buf), "%.200s/.hushlogin", pw->pw_dir); 956 #ifdef HAVE_LOGIN_CAP 957 if (login_getcapbool(lc, "hushlogin", 0) || stat(buf, &st) >= 0) 958 return 1; 959 #else 960 if (stat(buf, &st) >= 0) 961 return 1; 962 #endif 963 return 0; 964 } 965 966 /* 967 * Sets the value of the given variable in the environment. If the variable 968 * already exists, its value is overridden. 969 */ 970 void 971 child_set_env(char ***envp, u_int *envsizep, const char *name, 972 const char *value) 973 { 974 char **env; 975 u_int envsize; 976 u_int i, namelen; 977 978 if (strchr(name, '=') != NULL) { 979 error("Invalid environment variable \"%.100s\"", name); 980 return; 981 } 982 983 /* 984 * Find the slot where the value should be stored. If the variable 985 * already exists, we reuse the slot; otherwise we append a new slot 986 * at the end of the array, expanding if necessary. 987 */ 988 env = *envp; 989 namelen = strlen(name); 990 for (i = 0; env[i]; i++) 991 if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=') 992 break; 993 if (env[i]) { 994 /* Reuse the slot. */ 995 free(env[i]); 996 } else { 997 /* New variable. Expand if necessary. */ 998 envsize = *envsizep; 999 if (i >= envsize - 1) { 1000 if (envsize >= 1000) 1001 fatal("child_set_env: too many env vars"); 1002 envsize += 50; 1003 env = (*envp) = xreallocarray(env, envsize, sizeof(char *)); 1004 *envsizep = envsize; 1005 } 1006 /* Need to set the NULL pointer at end of array beyond the new slot. */ 1007 env[i + 1] = NULL; 1008 } 1009 1010 /* Allocate space and format the variable in the appropriate slot. */ 1011 env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1); 1012 snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value); 1013 } 1014 1015 #ifdef HAVE_LOGIN_CAP 1016 /* 1017 * Sets any environment variables specified in login.conf. 1018 * Taken from: 1019 * NetBSD: login_cap.c,v 1.11 2001/07/22 13:34:01 wiz Exp 1020 * Modified to use child_set_env instead of setenv. 1021 */ 1022 static void 1023 lc_setuserenv(char ***env, u_int *envsize, login_cap_t *lcp) 1024 { 1025 const char *stop = ", \t"; 1026 int i, count; 1027 char *ptr; 1028 char **res; 1029 char *str = login_getcapstr(lcp, "setenv", NULL, NULL); 1030 1031 if (str == NULL || *str == '\0') 1032 return; 1033 1034 /* count the sub-strings */ 1035 for (i = 1, ptr = str; *ptr; i++) { 1036 ptr += strcspn(ptr, stop); 1037 if (*ptr) 1038 ptr++; 1039 } 1040 1041 /* allocate ptr array and string */ 1042 count = i; 1043 res = malloc(count * sizeof(char *) + strlen(str) + 1); 1044 1045 if (!res) 1046 return; 1047 1048 ptr = (char *)res + count * sizeof(char *); 1049 strcpy(ptr, str); 1050 1051 /* split string */ 1052 for (i = 0; *ptr && i < count; i++) { 1053 res[i] = ptr; 1054 ptr += strcspn(ptr, stop); 1055 if (*ptr) 1056 *ptr++ = '\0'; 1057 } 1058 1059 res[i] = NULL; 1060 1061 for (i = 0; i < count && res[i]; i++) { 1062 if (*res[i] != '\0') { 1063 if ((ptr = strchr(res[i], '=')) != NULL) 1064 *ptr++ = '\0'; 1065 else 1066 ptr = __UNCONST(""); 1067 child_set_env(env, envsize, res[i], ptr); 1068 } 1069 } 1070 1071 free(res); 1072 return; 1073 } 1074 #endif 1075 1076 /* 1077 * Reads environment variables from the given file and adds/overrides them 1078 * into the environment. If the file does not exist, this does nothing. 1079 * Otherwise, it must consist of empty lines, comments (line starts with '#') 1080 * and assignments of the form name=value. No other forms are allowed. 1081 */ 1082 static void 1083 read_environment_file(char ***env, u_int *envsize, 1084 const char *filename) 1085 { 1086 FILE *f; 1087 char buf[4096]; 1088 char *cp, *value; 1089 u_int lineno = 0; 1090 1091 f = fopen(filename, "r"); 1092 if (!f) 1093 return; 1094 1095 while (fgets(buf, sizeof(buf), f)) { 1096 if (++lineno > 1000) 1097 fatal("Too many lines in environment file %s", filename); 1098 for (cp = buf; *cp == ' ' || *cp == '\t'; cp++) 1099 ; 1100 if (!*cp || *cp == '#' || *cp == '\n') 1101 continue; 1102 1103 cp[strcspn(cp, "\n")] = '\0'; 1104 1105 value = strchr(cp, '='); 1106 if (value == NULL) { 1107 fprintf(stderr, "Bad line %u in %.100s\n", lineno, 1108 filename); 1109 continue; 1110 } 1111 /* 1112 * Replace the equals sign by nul, and advance value to 1113 * the value string. 1114 */ 1115 *value = '\0'; 1116 value++; 1117 child_set_env(env, envsize, cp, value); 1118 } 1119 fclose(f); 1120 } 1121 1122 #ifdef USE_PAM 1123 void copy_environment(char **, char ***, u_int *); 1124 void copy_environment(char **source, char ***env, u_int *envsize) 1125 { 1126 char *var_name, *var_val; 1127 int i; 1128 1129 if (source == NULL) 1130 return; 1131 1132 for (i = 0; source[i] != NULL; i++) { 1133 var_name = xstrdup(source[i]); 1134 if ((var_val = strstr(var_name, "=")) == NULL) { 1135 free(var_name); 1136 continue; 1137 } 1138 *var_val++ = '\0'; 1139 1140 debug3("Copy environment: %s=%s", var_name, var_val); 1141 child_set_env(env, envsize, var_name, var_val); 1142 1143 free(var_name); 1144 } 1145 } 1146 #endif 1147 1148 static char ** 1149 do_setup_env(Session *s, const char *shell) 1150 { 1151 struct ssh *ssh = active_state; /* XXX */ 1152 char buf[256]; 1153 u_int i, envsize; 1154 char **env, *laddr; 1155 struct passwd *pw = s->pw; 1156 1157 /* Initialize the environment. */ 1158 envsize = 100; 1159 env = xcalloc(envsize, sizeof(char *)); 1160 env[0] = NULL; 1161 1162 #ifdef GSSAPI 1163 /* Allow any GSSAPI methods that we've used to alter 1164 * the childs environment as they see fit 1165 */ 1166 ssh_gssapi_do_child(&env, &envsize); 1167 #endif 1168 1169 if (!options.use_login) { 1170 #ifdef HAVE_LOGIN_CAP 1171 lc_setuserenv(&env, &envsize, lc); 1172 #endif 1173 /* Set basic environment. */ 1174 for (i = 0; i < s->num_env; i++) 1175 child_set_env(&env, &envsize, s->env[i].name, 1176 s->env[i].val); 1177 1178 child_set_env(&env, &envsize, "USER", pw->pw_name); 1179 child_set_env(&env, &envsize, "LOGNAME", pw->pw_name); 1180 child_set_env(&env, &envsize, "HOME", pw->pw_dir); 1181 #ifdef HAVE_LOGIN_CAP 1182 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETPATH) < 0) 1183 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); 1184 else 1185 child_set_env(&env, &envsize, "PATH", getenv("PATH")); 1186 #else 1187 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); 1188 #endif 1189 1190 snprintf(buf, sizeof buf, "%.200s/%.50s", 1191 _PATH_MAILDIR, pw->pw_name); 1192 child_set_env(&env, &envsize, "MAIL", buf); 1193 1194 /* Normal systems set SHELL by default. */ 1195 child_set_env(&env, &envsize, "SHELL", shell); 1196 } 1197 if (getenv("TZ")) 1198 child_set_env(&env, &envsize, "TZ", getenv("TZ")); 1199 1200 /* Set custom environment options from RSA authentication. */ 1201 if (!options.use_login) { 1202 while (custom_environment) { 1203 struct envstring *ce = custom_environment; 1204 char *str = ce->s; 1205 1206 for (i = 0; str[i] != '=' && str[i]; i++) 1207 ; 1208 if (str[i] == '=') { 1209 str[i] = 0; 1210 child_set_env(&env, &envsize, str, str + i + 1); 1211 } 1212 custom_environment = ce->next; 1213 free(ce->s); 1214 free(ce); 1215 } 1216 } 1217 1218 /* SSH_CLIENT deprecated */ 1219 snprintf(buf, sizeof buf, "%.50s %d %d", 1220 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 1221 ssh_local_port(ssh)); 1222 child_set_env(&env, &envsize, "SSH_CLIENT", buf); 1223 1224 laddr = get_local_ipaddr(packet_get_connection_in()); 1225 snprintf(buf, sizeof buf, "%.50s %d %.50s %d", 1226 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 1227 laddr, ssh_local_port(ssh)); 1228 free(laddr); 1229 child_set_env(&env, &envsize, "SSH_CONNECTION", buf); 1230 1231 if (s->ttyfd != -1) 1232 child_set_env(&env, &envsize, "SSH_TTY", s->tty); 1233 if (s->term) 1234 child_set_env(&env, &envsize, "TERM", s->term); 1235 if (s->display) 1236 child_set_env(&env, &envsize, "DISPLAY", s->display); 1237 if (original_command) 1238 child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND", 1239 original_command); 1240 #ifdef KRB4 1241 if (s->authctxt->krb4_ticket_file) 1242 child_set_env(&env, &envsize, "KRBTKFILE", 1243 s->authctxt->krb4_ticket_file); 1244 #endif 1245 #ifdef KRB5 1246 if (s->authctxt->krb5_ticket_file) 1247 child_set_env(&env, &envsize, "KRB5CCNAME", 1248 s->authctxt->krb5_ticket_file); 1249 #endif 1250 #ifdef USE_PAM 1251 /* 1252 * Pull in any environment variables that may have 1253 * been set by PAM. 1254 */ 1255 if (options.use_pam && !options.use_login) { 1256 char **p; 1257 1258 p = fetch_pam_child_environment(); 1259 copy_environment(p, &env, &envsize); 1260 free_pam_environment(p); 1261 1262 p = fetch_pam_environment(); 1263 copy_environment(p, &env, &envsize); 1264 free_pam_environment(p); 1265 } 1266 #endif /* USE_PAM */ 1267 1268 if (auth_sock_name != NULL) 1269 child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME, 1270 auth_sock_name); 1271 1272 /* read $HOME/.ssh/environment. */ 1273 if (options.permit_user_env && !options.use_login) { 1274 snprintf(buf, sizeof buf, "%.200s/.ssh/environment", 1275 pw->pw_dir); 1276 read_environment_file(&env, &envsize, buf); 1277 } 1278 if (debug_flag) { 1279 /* dump the environment */ 1280 fprintf(stderr, "Environment:\n"); 1281 for (i = 0; env[i]; i++) 1282 fprintf(stderr, " %.200s\n", env[i]); 1283 } 1284 return env; 1285 } 1286 1287 /* 1288 * Run $HOME/.ssh/rc, /etc/ssh/sshrc, or xauth (whichever is found 1289 * first in this order). 1290 */ 1291 static void 1292 do_rc_files(Session *s, const char *shell) 1293 { 1294 FILE *f = NULL; 1295 char cmd[1024]; 1296 int do_xauth; 1297 struct stat st; 1298 1299 do_xauth = 1300 s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL; 1301 1302 /* ignore _PATH_SSH_USER_RC for subsystems and admin forced commands */ 1303 if (!s->is_subsystem && options.adm_forced_command == NULL && 1304 !no_user_rc && options.permit_user_rc && 1305 stat(_PATH_SSH_USER_RC, &st) >= 0) { 1306 snprintf(cmd, sizeof cmd, "%s -c '%s %s'", 1307 shell, _PATH_BSHELL, _PATH_SSH_USER_RC); 1308 if (debug_flag) 1309 fprintf(stderr, "Running %s\n", cmd); 1310 f = popen(cmd, "w"); 1311 if (f) { 1312 if (do_xauth) 1313 fprintf(f, "%s %s\n", s->auth_proto, 1314 s->auth_data); 1315 pclose(f); 1316 } else 1317 fprintf(stderr, "Could not run %s\n", 1318 _PATH_SSH_USER_RC); 1319 } else if (stat(_PATH_SSH_SYSTEM_RC, &st) >= 0) { 1320 if (debug_flag) 1321 fprintf(stderr, "Running %s %s\n", _PATH_BSHELL, 1322 _PATH_SSH_SYSTEM_RC); 1323 f = popen(_PATH_BSHELL " " _PATH_SSH_SYSTEM_RC, "w"); 1324 if (f) { 1325 if (do_xauth) 1326 fprintf(f, "%s %s\n", s->auth_proto, 1327 s->auth_data); 1328 pclose(f); 1329 } else 1330 fprintf(stderr, "Could not run %s\n", 1331 _PATH_SSH_SYSTEM_RC); 1332 } else if (do_xauth && options.xauth_location != NULL) { 1333 /* Add authority data to .Xauthority if appropriate. */ 1334 if (debug_flag) { 1335 fprintf(stderr, 1336 "Running %.500s remove %.100s\n", 1337 options.xauth_location, s->auth_display); 1338 fprintf(stderr, 1339 "%.500s add %.100s %.100s %.100s\n", 1340 options.xauth_location, s->auth_display, 1341 s->auth_proto, s->auth_data); 1342 } 1343 snprintf(cmd, sizeof cmd, "%s -q -", 1344 options.xauth_location); 1345 f = popen(cmd, "w"); 1346 if (f) { 1347 fprintf(f, "remove %s\n", 1348 s->auth_display); 1349 fprintf(f, "add %s %s %s\n", 1350 s->auth_display, s->auth_proto, 1351 s->auth_data); 1352 pclose(f); 1353 } else { 1354 fprintf(stderr, "Could not run %s\n", 1355 cmd); 1356 } 1357 } 1358 } 1359 1360 static void 1361 do_nologin(struct passwd *pw) 1362 { 1363 FILE *f = NULL; 1364 char buf[1024], *nl, *def_nl = __UNCONST(_PATH_NOLOGIN); 1365 struct stat sb; 1366 1367 #ifdef HAVE_LOGIN_CAP 1368 if (login_getcapbool(lc, "ignorenologin", 0) || pw->pw_uid == 0) 1369 return; 1370 nl = login_getcapstr(lc, "nologin", def_nl, def_nl); 1371 #else 1372 if (pw->pw_uid == 0) 1373 return; 1374 nl = def_nl; 1375 #endif 1376 if (stat(nl, &sb) == -1) { 1377 if (nl != def_nl) 1378 free(nl); 1379 return; 1380 } 1381 1382 /* /etc/nologin exists. Print its contents if we can and exit. */ 1383 logit("User %.100s not allowed because %s exists", pw->pw_name, nl); 1384 if ((f = fopen(nl, "r")) != NULL) { 1385 while (fgets(buf, sizeof(buf), f)) 1386 fputs(buf, stderr); 1387 fclose(f); 1388 } 1389 exit(254); 1390 } 1391 1392 /* 1393 * Chroot into a directory after checking it for safety: all path components 1394 * must be root-owned directories with strict permissions. 1395 */ 1396 static void 1397 safely_chroot(const char *path, uid_t uid) 1398 { 1399 const char *cp; 1400 char component[PATH_MAX]; 1401 struct stat st; 1402 1403 if (*path != '/') 1404 fatal("chroot path does not begin at root"); 1405 if (strlen(path) >= sizeof(component)) 1406 fatal("chroot path too long"); 1407 1408 /* 1409 * Descend the path, checking that each component is a 1410 * root-owned directory with strict permissions. 1411 */ 1412 for (cp = path; cp != NULL;) { 1413 if ((cp = strchr(cp, '/')) == NULL) 1414 strlcpy(component, path, sizeof(component)); 1415 else { 1416 cp++; 1417 memcpy(component, path, cp - path); 1418 component[cp - path] = '\0'; 1419 } 1420 1421 debug3("%s: checking '%s'", __func__, component); 1422 1423 if (stat(component, &st) != 0) 1424 fatal("%s: stat(\"%s\"): %s", __func__, 1425 component, strerror(errno)); 1426 if (st.st_uid != 0 || (st.st_mode & 022) != 0) 1427 fatal("bad ownership or modes for chroot " 1428 "directory %s\"%s\"", 1429 cp == NULL ? "" : "component ", component); 1430 if (!S_ISDIR(st.st_mode)) 1431 fatal("chroot path %s\"%s\" is not a directory", 1432 cp == NULL ? "" : "component ", component); 1433 1434 } 1435 1436 if (chdir(path) == -1) 1437 fatal("Unable to chdir to chroot path \"%s\": " 1438 "%s", path, strerror(errno)); 1439 if (chroot(path) == -1) 1440 fatal("chroot(\"%s\"): %s", path, strerror(errno)); 1441 if (chdir("/") == -1) 1442 fatal("%s: chdir(/) after chroot: %s", 1443 __func__, strerror(errno)); 1444 verbose("Changed root directory to \"%s\"", path); 1445 } 1446 1447 /* Set login name, uid, gid, and groups. */ 1448 void 1449 do_setusercontext(struct passwd *pw) 1450 { 1451 char *chroot_path, *tmp; 1452 1453 if (getuid() == 0 || geteuid() == 0) { 1454 #ifdef HAVE_LOGIN_CAP 1455 # ifdef USE_PAM 1456 if (options.use_pam) { 1457 do_pam_setcred(use_privsep); 1458 } 1459 # endif /* USE_PAM */ 1460 /* Prepare groups */ 1461 if (setusercontext(lc, pw, pw->pw_uid, 1462 (LOGIN_SETALL & ~(LOGIN_SETPATH|LOGIN_SETUSER))) < 0) { 1463 perror("unable to set user context"); 1464 exit(1); 1465 } 1466 #else 1467 1468 if (setlogin(pw->pw_name) < 0) 1469 error("setlogin failed: %s", strerror(errno)); 1470 if (setgid(pw->pw_gid) < 0) { 1471 perror("setgid"); 1472 exit(1); 1473 } 1474 /* Initialize the group list. */ 1475 if (initgroups(pw->pw_name, pw->pw_gid) < 0) { 1476 perror("initgroups"); 1477 exit(1); 1478 } 1479 endgrent(); 1480 # ifdef USE_PAM 1481 /* 1482 * PAM credentials may take the form of supplementary groups. 1483 * These will have been wiped by the above initgroups() call. 1484 * Reestablish them here. 1485 */ 1486 if (options.use_pam) { 1487 do_pam_setcred(use_privsep); 1488 } 1489 # endif /* USE_PAM */ 1490 #endif 1491 if (!in_chroot && options.chroot_directory != NULL && 1492 strcasecmp(options.chroot_directory, "none") != 0) { 1493 tmp = tilde_expand_filename(options.chroot_directory, 1494 pw->pw_uid); 1495 chroot_path = percent_expand(tmp, "h", pw->pw_dir, 1496 "u", pw->pw_name, (char *)NULL); 1497 safely_chroot(chroot_path, pw->pw_uid); 1498 free(tmp); 1499 free(chroot_path); 1500 /* Make sure we don't attempt to chroot again */ 1501 free(options.chroot_directory); 1502 options.chroot_directory = NULL; 1503 in_chroot = 1; 1504 } 1505 1506 #ifdef HAVE_LOGIN_CAP 1507 /* Set UID */ 1508 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUSER) < 0) { 1509 perror("unable to set user context (setuser)"); 1510 exit(1); 1511 } 1512 #else 1513 /* Permanently switch to the desired uid. */ 1514 permanently_set_uid(pw); 1515 #endif 1516 } else if (options.chroot_directory != NULL && 1517 strcasecmp(options.chroot_directory, "none") != 0) { 1518 fatal("server lacks privileges to chroot to ChrootDirectory"); 1519 } 1520 1521 if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) 1522 fatal("Failed to set uids to %u.", (u_int) pw->pw_uid); 1523 } 1524 1525 __dead static void 1526 do_pwchange(Session *s) 1527 { 1528 fflush(NULL); 1529 fprintf(stderr, "WARNING: Your password has expired.\n"); 1530 if (s->ttyfd != -1) { 1531 fprintf(stderr, 1532 "You must change your password now and login again!\n"); 1533 execl(_PATH_PASSWD_PROG, "passwd", (char *)NULL); 1534 perror("passwd"); 1535 } else { 1536 fprintf(stderr, 1537 "Password change required but no TTY available.\n"); 1538 } 1539 exit(1); 1540 } 1541 1542 __dead static void 1543 launch_login(struct passwd *pw, const char *hostname) 1544 { 1545 /* Launch login(1). */ 1546 1547 execl("/usr/bin/login", "login", "-h", hostname, 1548 "-p", "-f", "--", pw->pw_name, (char *)NULL); 1549 1550 /* Login couldn't be executed, die. */ 1551 1552 perror("login"); 1553 exit(1); 1554 } 1555 1556 static void 1557 child_close_fds(void) 1558 { 1559 extern int auth_sock; 1560 1561 if (auth_sock != -1) { 1562 close(auth_sock); 1563 auth_sock = -1; 1564 } 1565 1566 if (packet_get_connection_in() == packet_get_connection_out()) 1567 close(packet_get_connection_in()); 1568 else { 1569 close(packet_get_connection_in()); 1570 close(packet_get_connection_out()); 1571 } 1572 /* 1573 * Close all descriptors related to channels. They will still remain 1574 * open in the parent. 1575 */ 1576 /* XXX better use close-on-exec? -markus */ 1577 channel_close_all(); 1578 1579 /* 1580 * Close any extra file descriptors. Note that there may still be 1581 * descriptors left by system functions. They will be closed later. 1582 */ 1583 endpwent(); 1584 1585 /* 1586 * Close any extra open file descriptors so that we don't have them 1587 * hanging around in clients. Note that we want to do this after 1588 * initgroups, because at least on Solaris 2.3 it leaves file 1589 * descriptors open. 1590 */ 1591 (void)closefrom(STDERR_FILENO + 1); 1592 } 1593 1594 /* 1595 * Performs common processing for the child, such as setting up the 1596 * environment, closing extra file descriptors, setting the user and group 1597 * ids, and executing the command or shell. 1598 */ 1599 #define ARGV_MAX 10 1600 void 1601 do_child(Session *s, const char *command) 1602 { 1603 struct ssh *ssh = active_state; /* XXX */ 1604 extern char **environ; 1605 char **env; 1606 char *argv[ARGV_MAX]; 1607 const char *shell, *shell0, *hostname = NULL; 1608 struct passwd *pw = s->pw; 1609 int r = 0; 1610 1611 /* remove hostkey from the child's memory */ 1612 destroy_sensitive_data(); 1613 1614 /* Force a password change */ 1615 if (s->authctxt->force_pwchange) { 1616 do_setusercontext(pw); 1617 child_close_fds(); 1618 do_pwchange(s); 1619 } 1620 1621 /* login(1) is only called if we execute the login shell */ 1622 if (options.use_login && command != NULL) 1623 options.use_login = 0; 1624 1625 /* 1626 * Login(1) does this as well, and it needs uid 0 for the "-h" 1627 * switch, so we let login(1) to this for us. 1628 */ 1629 if (!options.use_login) { 1630 do_nologin(pw); 1631 do_setusercontext(pw); 1632 /* 1633 * PAM session modules in do_setusercontext may have 1634 * generated messages, so if this in an interactive 1635 * login then display them too. 1636 */ 1637 if (!check_quietlogin(s, command)) 1638 display_loginmsg(); 1639 } 1640 #ifdef USE_PAM 1641 if (options.use_pam && !is_pam_session_open()) { 1642 debug3("PAM session not opened, exiting"); 1643 display_loginmsg(); 1644 exit(254); 1645 } 1646 #endif 1647 1648 /* 1649 * Get the shell from the password data. An empty shell field is 1650 * legal, and means /bin/sh. 1651 */ 1652 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; 1653 1654 /* 1655 * Make sure $SHELL points to the shell from the password file, 1656 * even if shell is overridden from login.conf 1657 */ 1658 env = do_setup_env(s, shell); 1659 1660 #ifdef HAVE_LOGIN_CAP 1661 shell = login_getcapstr(lc, "shell", __UNCONST(shell), 1662 __UNCONST(shell)); 1663 #endif 1664 1665 /* we have to stash the hostname before we close our socket. */ 1666 if (options.use_login) 1667 hostname = session_get_remote_name_or_ip(ssh, utmp_len, 1668 options.use_dns); 1669 /* 1670 * Close the connection descriptors; note that this is the child, and 1671 * the server will still have the socket open, and it is important 1672 * that we do not shutdown it. Note that the descriptors cannot be 1673 * closed before building the environment, as we call 1674 * ssh_remote_ipaddr there. 1675 */ 1676 child_close_fds(); 1677 1678 /* 1679 * Must take new environment into use so that .ssh/rc, 1680 * /etc/ssh/sshrc and xauth are run in the proper environment. 1681 */ 1682 environ = env; 1683 1684 #ifdef KRB5 1685 /* 1686 * At this point, we check to see if AFS is active and if we have 1687 * a valid Kerberos 5 TGT. If so, it seems like a good idea to see 1688 * if we can (and need to) extend the ticket into an AFS token. If 1689 * we don't do this, we run into potential problems if the user's 1690 * home directory is in AFS and it's not world-readable. 1691 */ 1692 1693 if (options.kerberos_get_afs_token && k_hasafs() && 1694 (s->authctxt->krb5_ctx != NULL)) { 1695 char cell[64]; 1696 1697 debug("Getting AFS token"); 1698 1699 k_setpag(); 1700 1701 if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0) 1702 krb5_afslog(s->authctxt->krb5_ctx, 1703 s->authctxt->krb5_fwd_ccache, cell, NULL); 1704 1705 krb5_afslog_home(s->authctxt->krb5_ctx, 1706 s->authctxt->krb5_fwd_ccache, NULL, NULL, pw->pw_dir); 1707 } 1708 #endif 1709 1710 /* Change current directory to the user's home directory. */ 1711 if (chdir(pw->pw_dir) < 0) { 1712 /* Suppress missing homedir warning for chroot case */ 1713 r = login_getcapbool(lc, "requirehome", 0); 1714 if (r || !in_chroot) { 1715 fprintf(stderr, "Could not chdir to home " 1716 "directory %s: %s\n", pw->pw_dir, 1717 strerror(errno)); 1718 } 1719 if (r) 1720 exit(1); 1721 } 1722 1723 (void)closefrom(STDERR_FILENO + 1); 1724 1725 if (!options.use_login) 1726 do_rc_files(s, shell); 1727 1728 /* restore SIGPIPE for child */ 1729 signal(SIGPIPE, SIG_DFL); 1730 1731 if (s->is_subsystem == SUBSYSTEM_INT_SFTP_ERROR) { 1732 printf("This service allows sftp connections only.\n"); 1733 fflush(NULL); 1734 exit(1); 1735 } else if (s->is_subsystem == SUBSYSTEM_INT_SFTP) { 1736 extern int optind, optreset; 1737 int i; 1738 char *p, *args; 1739 1740 setproctitle("%s@%s", s->pw->pw_name, INTERNAL_SFTP_NAME); 1741 args = xstrdup(command ? command : "sftp-server"); 1742 for (i = 0, (p = strtok(args, " ")); p; (p = strtok(NULL, " "))) 1743 if (i < ARGV_MAX - 1) 1744 argv[i++] = p; 1745 argv[i] = NULL; 1746 optind = optreset = 1; 1747 __progname = argv[0]; 1748 exit(sftp_server_main(i, argv, s->pw)); 1749 } 1750 1751 fflush(NULL); 1752 1753 if (options.use_login) { 1754 launch_login(pw, hostname); 1755 /* NEVERREACHED */ 1756 } 1757 1758 /* Get the last component of the shell name. */ 1759 if ((shell0 = strrchr(shell, '/')) != NULL) 1760 shell0++; 1761 else 1762 shell0 = shell; 1763 1764 /* 1765 * If we have no command, execute the shell. In this case, the shell 1766 * name to be passed in argv[0] is preceded by '-' to indicate that 1767 * this is a login shell. 1768 */ 1769 if (!command) { 1770 char argv0[256]; 1771 1772 /* Start the shell. Set initial character to '-'. */ 1773 argv0[0] = '-'; 1774 1775 if (strlcpy(argv0 + 1, shell0, sizeof(argv0) - 1) 1776 >= sizeof(argv0) - 1) { 1777 errno = EINVAL; 1778 perror(shell); 1779 exit(1); 1780 } 1781 1782 /* Execute the shell. */ 1783 argv[0] = argv0; 1784 argv[1] = NULL; 1785 execve(shell, argv, env); 1786 1787 /* Executing the shell failed. */ 1788 perror(shell); 1789 exit(1); 1790 } 1791 /* 1792 * Execute the command using the user's shell. This uses the -c 1793 * option to execute the command. 1794 */ 1795 argv[0] = __UNCONST(shell0); 1796 argv[1] = __UNCONST("-c"); 1797 argv[2] = __UNCONST(command); 1798 argv[3] = NULL; 1799 execve(shell, argv, env); 1800 perror(shell); 1801 exit(1); 1802 } 1803 1804 void 1805 session_unused(int id) 1806 { 1807 debug3("%s: session id %d unused", __func__, id); 1808 if (id >= options.max_sessions || 1809 id >= sessions_nalloc) { 1810 fatal("%s: insane session id %d (max %d nalloc %d)", 1811 __func__, id, options.max_sessions, sessions_nalloc); 1812 } 1813 memset(&sessions[id], 0, sizeof(*sessions)); 1814 sessions[id].self = id; 1815 sessions[id].used = 0; 1816 sessions[id].chanid = -1; 1817 sessions[id].ptyfd = -1; 1818 sessions[id].ttyfd = -1; 1819 sessions[id].ptymaster = -1; 1820 sessions[id].x11_chanids = NULL; 1821 sessions[id].next_unused = sessions_first_unused; 1822 sessions_first_unused = id; 1823 } 1824 1825 Session * 1826 session_new(void) 1827 { 1828 Session *s, *tmp; 1829 1830 if (sessions_first_unused == -1) { 1831 if (sessions_nalloc >= options.max_sessions) 1832 return NULL; 1833 debug2("%s: allocate (allocated %d max %d)", 1834 __func__, sessions_nalloc, options.max_sessions); 1835 tmp = xreallocarray(sessions, sessions_nalloc + 1, 1836 sizeof(*sessions)); 1837 if (tmp == NULL) { 1838 error("%s: cannot allocate %d sessions", 1839 __func__, sessions_nalloc + 1); 1840 return NULL; 1841 } 1842 sessions = tmp; 1843 session_unused(sessions_nalloc++); 1844 } 1845 1846 if (sessions_first_unused >= sessions_nalloc || 1847 sessions_first_unused < 0) { 1848 fatal("%s: insane first_unused %d max %d nalloc %d", 1849 __func__, sessions_first_unused, options.max_sessions, 1850 sessions_nalloc); 1851 } 1852 1853 s = &sessions[sessions_first_unused]; 1854 if (s->used) { 1855 fatal("%s: session %d already used", 1856 __func__, sessions_first_unused); 1857 } 1858 sessions_first_unused = s->next_unused; 1859 s->used = 1; 1860 s->next_unused = -1; 1861 debug("session_new: session %d", s->self); 1862 1863 return s; 1864 } 1865 1866 static void 1867 session_dump(void) 1868 { 1869 int i; 1870 for (i = 0; i < sessions_nalloc; i++) { 1871 Session *s = &sessions[i]; 1872 1873 debug("dump: used %d next_unused %d session %d %p " 1874 "channel %d pid %ld", 1875 s->used, 1876 s->next_unused, 1877 s->self, 1878 s, 1879 s->chanid, 1880 (long)s->pid); 1881 } 1882 } 1883 1884 int 1885 session_open(Authctxt *authctxt, int chanid) 1886 { 1887 Session *s = session_new(); 1888 debug("session_open: channel %d", chanid); 1889 if (s == NULL) { 1890 error("no more sessions"); 1891 return 0; 1892 } 1893 s->authctxt = authctxt; 1894 s->pw = authctxt->pw; 1895 if (s->pw == NULL || !authctxt->valid) 1896 fatal("no user for session %d", s->self); 1897 debug("session_open: session %d: link with channel %d", s->self, chanid); 1898 s->chanid = chanid; 1899 return 1; 1900 } 1901 1902 Session * 1903 session_by_tty(char *tty) 1904 { 1905 int i; 1906 for (i = 0; i < sessions_nalloc; i++) { 1907 Session *s = &sessions[i]; 1908 if (s->used && s->ttyfd != -1 && strcmp(s->tty, tty) == 0) { 1909 debug("session_by_tty: session %d tty %s", i, tty); 1910 return s; 1911 } 1912 } 1913 debug("session_by_tty: unknown tty %.100s", tty); 1914 session_dump(); 1915 return NULL; 1916 } 1917 1918 static Session * 1919 session_by_channel(int id) 1920 { 1921 int i; 1922 for (i = 0; i < sessions_nalloc; i++) { 1923 Session *s = &sessions[i]; 1924 if (s->used && s->chanid == id) { 1925 debug("session_by_channel: session %d channel %d", 1926 i, id); 1927 return s; 1928 } 1929 } 1930 debug("session_by_channel: unknown channel %d", id); 1931 session_dump(); 1932 return NULL; 1933 } 1934 1935 static Session * 1936 session_by_x11_channel(int id) 1937 { 1938 int i, j; 1939 1940 for (i = 0; i < sessions_nalloc; i++) { 1941 Session *s = &sessions[i]; 1942 1943 if (s->x11_chanids == NULL || !s->used) 1944 continue; 1945 for (j = 0; s->x11_chanids[j] != -1; j++) { 1946 if (s->x11_chanids[j] == id) { 1947 debug("session_by_x11_channel: session %d " 1948 "channel %d", s->self, id); 1949 return s; 1950 } 1951 } 1952 } 1953 debug("session_by_x11_channel: unknown channel %d", id); 1954 session_dump(); 1955 return NULL; 1956 } 1957 1958 static Session * 1959 session_by_pid(pid_t pid) 1960 { 1961 int i; 1962 debug("session_by_pid: pid %ld", (long)pid); 1963 for (i = 0; i < sessions_nalloc; i++) { 1964 Session *s = &sessions[i]; 1965 if (s->used && s->pid == pid) 1966 return s; 1967 } 1968 error("session_by_pid: unknown pid %ld", (long)pid); 1969 session_dump(); 1970 return NULL; 1971 } 1972 1973 static int 1974 session_window_change_req(Session *s) 1975 { 1976 s->col = packet_get_int(); 1977 s->row = packet_get_int(); 1978 s->xpixel = packet_get_int(); 1979 s->ypixel = packet_get_int(); 1980 packet_check_eom(); 1981 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 1982 return 1; 1983 } 1984 1985 static int 1986 session_pty_req(Session *s) 1987 { 1988 u_int len; 1989 int n_bytes; 1990 1991 if (no_pty_flag || !options.permit_tty) { 1992 debug("Allocating a pty not permitted for this authentication."); 1993 return 0; 1994 } 1995 if (s->ttyfd != -1) { 1996 packet_disconnect("Protocol error: you already have a pty."); 1997 return 0; 1998 } 1999 2000 s->term = packet_get_string(&len); 2001 2002 if (compat20) { 2003 s->col = packet_get_int(); 2004 s->row = packet_get_int(); 2005 } else { 2006 s->row = packet_get_int(); 2007 s->col = packet_get_int(); 2008 } 2009 s->xpixel = packet_get_int(); 2010 s->ypixel = packet_get_int(); 2011 2012 if (strcmp(s->term, "") == 0) { 2013 free(s->term); 2014 s->term = NULL; 2015 } 2016 2017 /* Allocate a pty and open it. */ 2018 debug("Allocating pty."); 2019 if (!PRIVSEP(pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, 2020 sizeof(s->tty)))) { 2021 free(s->term); 2022 s->term = NULL; 2023 s->ptyfd = -1; 2024 s->ttyfd = -1; 2025 error("session_pty_req: session %d alloc failed", s->self); 2026 return 0; 2027 } 2028 debug("session_pty_req: session %d alloc %s", s->self, s->tty); 2029 2030 /* for SSH1 the tty modes length is not given */ 2031 if (!compat20) 2032 n_bytes = packet_remaining(); 2033 tty_parse_modes(s->ttyfd, &n_bytes); 2034 2035 if (!use_privsep) 2036 pty_setowner(s->pw, s->tty); 2037 2038 /* Set window size from the packet. */ 2039 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 2040 2041 packet_check_eom(); 2042 session_proctitle(s); 2043 return 1; 2044 } 2045 2046 static int 2047 session_subsystem_req(Session *s) 2048 { 2049 struct stat st; 2050 u_int len; 2051 int success = 0; 2052 char *prog, *cmd; 2053 u_int i; 2054 2055 s->subsys = packet_get_string(&len); 2056 packet_check_eom(); 2057 debug2("subsystem request for %.100s by user %s", s->subsys, 2058 s->pw->pw_name); 2059 2060 for (i = 0; i < options.num_subsystems; i++) { 2061 if (strcmp(s->subsys, options.subsystem_name[i]) == 0) { 2062 prog = options.subsystem_command[i]; 2063 cmd = options.subsystem_args[i]; 2064 if (strcmp(INTERNAL_SFTP_NAME, prog) == 0) { 2065 s->is_subsystem = SUBSYSTEM_INT_SFTP; 2066 debug("subsystem: %s", prog); 2067 } else { 2068 if (stat(prog, &st) < 0) 2069 debug("subsystem: cannot stat %s: %s", 2070 prog, strerror(errno)); 2071 s->is_subsystem = SUBSYSTEM_EXT; 2072 debug("subsystem: exec() %s", cmd); 2073 } 2074 success = do_exec(s, cmd) == 0; 2075 break; 2076 } 2077 } 2078 2079 if (!success) 2080 logit("subsystem request for %.100s by user %s failed, " 2081 "subsystem not found", s->subsys, s->pw->pw_name); 2082 2083 return success; 2084 } 2085 2086 static int 2087 session_x11_req(Session *s) 2088 { 2089 int success; 2090 2091 if (s->auth_proto != NULL || s->auth_data != NULL) { 2092 error("session_x11_req: session %d: " 2093 "x11 forwarding already active", s->self); 2094 return 0; 2095 } 2096 s->single_connection = packet_get_char(); 2097 s->auth_proto = packet_get_string(NULL); 2098 s->auth_data = packet_get_string(NULL); 2099 s->screen = packet_get_int(); 2100 packet_check_eom(); 2101 2102 if (xauth_valid_string(s->auth_proto) && 2103 xauth_valid_string(s->auth_data)) 2104 success = session_setup_x11fwd(s); 2105 else { 2106 success = 0; 2107 error("Invalid X11 forwarding data"); 2108 } 2109 if (!success) { 2110 free(s->auth_proto); 2111 free(s->auth_data); 2112 s->auth_proto = NULL; 2113 s->auth_data = NULL; 2114 } 2115 return success; 2116 } 2117 2118 static int 2119 session_shell_req(Session *s) 2120 { 2121 packet_check_eom(); 2122 return do_exec(s, NULL) == 0; 2123 } 2124 2125 static int 2126 session_exec_req(Session *s) 2127 { 2128 u_int len, success; 2129 2130 char *command = packet_get_string(&len); 2131 packet_check_eom(); 2132 success = do_exec(s, command) == 0; 2133 free(command); 2134 return success; 2135 } 2136 2137 static int 2138 session_break_req(Session *s) 2139 { 2140 2141 packet_get_int(); /* ignored */ 2142 packet_check_eom(); 2143 2144 if (s->ptymaster == -1 || tcsendbreak(s->ptymaster, 0) < 0) 2145 return 0; 2146 return 1; 2147 } 2148 2149 static int 2150 session_env_req(Session *s) 2151 { 2152 char *name, *val; 2153 u_int name_len, val_len, i; 2154 2155 name = packet_get_cstring(&name_len); 2156 val = packet_get_cstring(&val_len); 2157 packet_check_eom(); 2158 2159 /* Don't set too many environment variables */ 2160 if (s->num_env > 128) { 2161 debug2("Ignoring env request %s: too many env vars", name); 2162 goto fail; 2163 } 2164 2165 for (i = 0; i < options.num_accept_env; i++) { 2166 if (match_pattern(name, options.accept_env[i])) { 2167 debug2("Setting env %d: %s=%s", s->num_env, name, val); 2168 s->env = xreallocarray(s->env, s->num_env + 1, 2169 sizeof(*s->env)); 2170 s->env[s->num_env].name = name; 2171 s->env[s->num_env].val = val; 2172 s->num_env++; 2173 return (1); 2174 } 2175 } 2176 debug2("Ignoring env request %s: disallowed name", name); 2177 2178 fail: 2179 free(name); 2180 free(val); 2181 return (0); 2182 } 2183 2184 static int 2185 session_auth_agent_req(Session *s) 2186 { 2187 static int called = 0; 2188 packet_check_eom(); 2189 if (no_agent_forwarding_flag || !options.allow_agent_forwarding) { 2190 debug("session_auth_agent_req: no_agent_forwarding_flag"); 2191 return 0; 2192 } 2193 if (called) { 2194 return 0; 2195 } else { 2196 called = 1; 2197 return auth_input_request_forwarding(s->pw); 2198 } 2199 } 2200 2201 int 2202 session_input_channel_req(Channel *c, const char *rtype) 2203 { 2204 int success = 0; 2205 Session *s; 2206 2207 if ((s = session_by_channel(c->self)) == NULL) { 2208 logit("session_input_channel_req: no session %d req %.100s", 2209 c->self, rtype); 2210 return 0; 2211 } 2212 debug("session_input_channel_req: session %d req %s", s->self, rtype); 2213 2214 /* 2215 * a session is in LARVAL state until a shell, a command 2216 * or a subsystem is executed 2217 */ 2218 if (c->type == SSH_CHANNEL_LARVAL) { 2219 if (strcmp(rtype, "shell") == 0) { 2220 success = session_shell_req(s); 2221 } else if (strcmp(rtype, "exec") == 0) { 2222 success = session_exec_req(s); 2223 } else if (strcmp(rtype, "pty-req") == 0) { 2224 success = session_pty_req(s); 2225 } else if (strcmp(rtype, "x11-req") == 0) { 2226 success = session_x11_req(s); 2227 } else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) { 2228 success = session_auth_agent_req(s); 2229 } else if (strcmp(rtype, "subsystem") == 0) { 2230 success = session_subsystem_req(s); 2231 } else if (strcmp(rtype, "env") == 0) { 2232 success = session_env_req(s); 2233 } 2234 } 2235 if (strcmp(rtype, "window-change") == 0) { 2236 success = session_window_change_req(s); 2237 } else if (strcmp(rtype, "break") == 0) { 2238 success = session_break_req(s); 2239 } 2240 2241 return success; 2242 } 2243 2244 void 2245 session_set_fds(Session *s, int fdin, int fdout, int fderr, int ignore_fderr, 2246 int is_tty) 2247 { 2248 if (!compat20) 2249 fatal("session_set_fds: called for proto != 2.0"); 2250 /* 2251 * now that have a child and a pipe to the child, 2252 * we can activate our channel and register the fd's 2253 */ 2254 if (s->chanid == -1) 2255 fatal("no channel for session %d", s->self); 2256 if(options.hpn_disabled) 2257 channel_set_fds(s->chanid, 2258 fdout, fdin, fderr, 2259 ignore_fderr ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ, 2260 1, is_tty, CHAN_SES_WINDOW_DEFAULT); 2261 else 2262 channel_set_fds(s->chanid, 2263 fdout, fdin, fderr, 2264 ignore_fderr ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ, 2265 1, is_tty, options.hpn_buffer_size); 2266 } 2267 2268 /* 2269 * Function to perform pty cleanup. Also called if we get aborted abnormally 2270 * (e.g., due to a dropped connection). 2271 */ 2272 void 2273 session_pty_cleanup2(Session *s) 2274 { 2275 if (s == NULL) { 2276 error("session_pty_cleanup: no session"); 2277 return; 2278 } 2279 if (s->ttyfd == -1) 2280 return; 2281 2282 debug("session_pty_cleanup: session %d release %s", s->self, s->tty); 2283 2284 /* Record that the user has logged out. */ 2285 if (s->pid != 0) 2286 record_logout(s->pid, s->tty); 2287 2288 /* Release the pseudo-tty. */ 2289 if (getuid() == 0) 2290 pty_release(s->tty); 2291 2292 /* 2293 * Close the server side of the socket pairs. We must do this after 2294 * the pty cleanup, so that another process doesn't get this pty 2295 * while we're still cleaning up. 2296 */ 2297 if (s->ptymaster != -1 && close(s->ptymaster) < 0) 2298 error("close(s->ptymaster/%d): %s", 2299 s->ptymaster, strerror(errno)); 2300 2301 /* unlink pty from session */ 2302 s->ttyfd = -1; 2303 } 2304 2305 void 2306 session_pty_cleanup(Session *s) 2307 { 2308 PRIVSEP(session_pty_cleanup2(s)); 2309 } 2310 2311 static const char * 2312 sig2name(int sig) 2313 { 2314 #define SSH_SIG(x) if (sig == SIG ## x) return #x 2315 SSH_SIG(ABRT); 2316 SSH_SIG(ALRM); 2317 SSH_SIG(FPE); 2318 SSH_SIG(HUP); 2319 SSH_SIG(ILL); 2320 SSH_SIG(INT); 2321 SSH_SIG(KILL); 2322 SSH_SIG(PIPE); 2323 SSH_SIG(QUIT); 2324 SSH_SIG(SEGV); 2325 SSH_SIG(TERM); 2326 SSH_SIG(USR1); 2327 SSH_SIG(USR2); 2328 #undef SSH_SIG 2329 return "SIG@openssh.com"; 2330 } 2331 2332 static void 2333 session_close_x11(int id) 2334 { 2335 Channel *c; 2336 2337 if ((c = channel_by_id(id)) == NULL) { 2338 debug("session_close_x11: x11 channel %d missing", id); 2339 } else { 2340 /* Detach X11 listener */ 2341 debug("session_close_x11: detach x11 channel %d", id); 2342 channel_cancel_cleanup(id); 2343 if (c->ostate != CHAN_OUTPUT_CLOSED) 2344 chan_mark_dead(c); 2345 } 2346 } 2347 2348 static void 2349 session_close_single_x11(int id, void *arg) 2350 { 2351 Session *s; 2352 u_int i; 2353 2354 debug3("session_close_single_x11: channel %d", id); 2355 channel_cancel_cleanup(id); 2356 if ((s = session_by_x11_channel(id)) == NULL) 2357 fatal("session_close_single_x11: no x11 channel %d", id); 2358 for (i = 0; s->x11_chanids[i] != -1; i++) { 2359 debug("session_close_single_x11: session %d: " 2360 "closing channel %d", s->self, s->x11_chanids[i]); 2361 /* 2362 * The channel "id" is already closing, but make sure we 2363 * close all of its siblings. 2364 */ 2365 if (s->x11_chanids[i] != id) 2366 session_close_x11(s->x11_chanids[i]); 2367 } 2368 free(s->x11_chanids); 2369 s->x11_chanids = NULL; 2370 free(s->display); 2371 s->display = NULL; 2372 free(s->auth_proto); 2373 s->auth_proto = NULL; 2374 free(s->auth_data); 2375 s->auth_data = NULL; 2376 free(s->auth_display); 2377 s->auth_display = NULL; 2378 } 2379 2380 static void 2381 session_exit_message(Session *s, int status) 2382 { 2383 Channel *c; 2384 2385 if ((c = channel_lookup(s->chanid)) == NULL) 2386 fatal("session_exit_message: session %d: no channel %d", 2387 s->self, s->chanid); 2388 debug("session_exit_message: session %d channel %d pid %ld", 2389 s->self, s->chanid, (long)s->pid); 2390 2391 if (WIFEXITED(status)) { 2392 channel_request_start(s->chanid, "exit-status", 0); 2393 packet_put_int(WEXITSTATUS(status)); 2394 packet_send(); 2395 } else if (WIFSIGNALED(status)) { 2396 channel_request_start(s->chanid, "exit-signal", 0); 2397 packet_put_cstring(sig2name(WTERMSIG(status))); 2398 packet_put_char(WCOREDUMP(status)? 1 : 0); 2399 packet_put_cstring(""); 2400 packet_put_cstring(""); 2401 packet_send(); 2402 } else { 2403 /* Some weird exit cause. Just exit. */ 2404 packet_disconnect("wait returned status %04x.", status); 2405 } 2406 2407 /* disconnect channel */ 2408 debug("session_exit_message: release channel %d", s->chanid); 2409 2410 /* 2411 * Adjust cleanup callback attachment to send close messages when 2412 * the channel gets EOF. The session will be then be closed 2413 * by session_close_by_channel when the childs close their fds. 2414 */ 2415 channel_register_cleanup(c->self, session_close_by_channel, 1); 2416 2417 /* 2418 * emulate a write failure with 'chan_write_failed', nobody will be 2419 * interested in data we write. 2420 * Note that we must not call 'chan_read_failed', since there could 2421 * be some more data waiting in the pipe. 2422 */ 2423 if (c->ostate != CHAN_OUTPUT_CLOSED) 2424 chan_write_failed(c); 2425 } 2426 2427 void 2428 session_close(Session *s) 2429 { 2430 struct ssh *ssh = active_state; /* XXX */ 2431 u_int i; 2432 2433 verbose("Close session: user %s from %.200s port %d id %d", 2434 s->pw->pw_name, 2435 ssh_remote_ipaddr(ssh), 2436 ssh_remote_port(ssh), 2437 s->self); 2438 2439 if (s->ttyfd != -1) 2440 session_pty_cleanup(s); 2441 free(s->term); 2442 free(s->display); 2443 free(s->x11_chanids); 2444 free(s->auth_display); 2445 free(s->auth_data); 2446 free(s->auth_proto); 2447 free(s->subsys); 2448 if (s->env != NULL) { 2449 for (i = 0; i < s->num_env; i++) { 2450 free(s->env[i].name); 2451 free(s->env[i].val); 2452 } 2453 free(s->env); 2454 } 2455 session_proctitle(s); 2456 session_unused(s->self); 2457 } 2458 2459 void 2460 session_close_by_pid(pid_t pid, int status) 2461 { 2462 Session *s = session_by_pid(pid); 2463 if (s == NULL) { 2464 debug("session_close_by_pid: no session for pid %ld", 2465 (long)pid); 2466 return; 2467 } 2468 if (s->chanid != -1) 2469 session_exit_message(s, status); 2470 if (s->ttyfd != -1) 2471 session_pty_cleanup(s); 2472 s->pid = 0; 2473 } 2474 2475 /* 2476 * this is called when a channel dies before 2477 * the session 'child' itself dies 2478 */ 2479 void 2480 session_close_by_channel(int id, void *arg) 2481 { 2482 Session *s = session_by_channel(id); 2483 u_int i; 2484 2485 if (s == NULL) { 2486 debug("session_close_by_channel: no session for id %d", id); 2487 return; 2488 } 2489 debug("session_close_by_channel: channel %d child %ld", 2490 id, (long)s->pid); 2491 if (s->pid != 0) { 2492 debug("session_close_by_channel: channel %d: has child", id); 2493 /* 2494 * delay detach of session, but release pty, since 2495 * the fd's to the child are already closed 2496 */ 2497 if (s->ttyfd != -1) 2498 session_pty_cleanup(s); 2499 return; 2500 } 2501 /* detach by removing callback */ 2502 channel_cancel_cleanup(s->chanid); 2503 2504 /* Close any X11 listeners associated with this session */ 2505 if (s->x11_chanids != NULL) { 2506 for (i = 0; s->x11_chanids[i] != -1; i++) { 2507 session_close_x11(s->x11_chanids[i]); 2508 s->x11_chanids[i] = -1; 2509 } 2510 } 2511 2512 s->chanid = -1; 2513 session_close(s); 2514 } 2515 2516 void 2517 session_destroy_all(void (*closefunc)(Session *)) 2518 { 2519 int i; 2520 for (i = 0; i < sessions_nalloc; i++) { 2521 Session *s = &sessions[i]; 2522 if (s->used) { 2523 if (closefunc != NULL) 2524 closefunc(s); 2525 else 2526 session_close(s); 2527 } 2528 } 2529 } 2530 2531 static char * 2532 session_tty_list(void) 2533 { 2534 static char buf[1024]; 2535 int i; 2536 buf[0] = '\0'; 2537 for (i = 0; i < sessions_nalloc; i++) { 2538 Session *s = &sessions[i]; 2539 if (s->used && s->ttyfd != -1) { 2540 char *p; 2541 if (buf[0] != '\0') 2542 strlcat(buf, ",", sizeof buf); 2543 if ((p = strstr(s->tty, "/pts/")) != NULL) 2544 p++; 2545 else { 2546 if ((p = strrchr(s->tty, '/')) != NULL) 2547 p++; 2548 else 2549 p = s->tty; 2550 } 2551 strlcat(buf, p, sizeof buf); 2552 } 2553 } 2554 if (buf[0] == '\0') 2555 strlcpy(buf, "notty", sizeof buf); 2556 return buf; 2557 } 2558 2559 void 2560 session_proctitle(Session *s) 2561 { 2562 if (s->pw == NULL) 2563 error("no user for session %d", s->self); 2564 else 2565 setproctitle("%s@%s", s->pw->pw_name, session_tty_list()); 2566 } 2567 2568 int 2569 session_setup_x11fwd(Session *s) 2570 { 2571 struct stat st; 2572 char display[512], auth_display[512]; 2573 char hostname[NI_MAXHOST]; 2574 u_int i; 2575 2576 if (no_x11_forwarding_flag) { 2577 packet_send_debug("X11 forwarding disabled in user configuration file."); 2578 return 0; 2579 } 2580 if (!options.x11_forwarding) { 2581 debug("X11 forwarding disabled in server configuration file."); 2582 return 0; 2583 } 2584 if (options.xauth_location == NULL || 2585 (stat(options.xauth_location, &st) == -1)) { 2586 packet_send_debug("No xauth program; cannot forward with spoofing."); 2587 return 0; 2588 } 2589 if (options.use_login) { 2590 packet_send_debug("X11 forwarding disabled; " 2591 "not compatible with UseLogin=yes."); 2592 return 0; 2593 } 2594 if (s->display != NULL) { 2595 debug("X11 display already set."); 2596 return 0; 2597 } 2598 if (x11_create_display_inet(options.x11_display_offset, 2599 options.x11_use_localhost, s->single_connection, 2600 &s->display_number, &s->x11_chanids) == -1) { 2601 debug("x11_create_display_inet failed."); 2602 return 0; 2603 } 2604 for (i = 0; s->x11_chanids[i] != -1; i++) { 2605 channel_register_cleanup(s->x11_chanids[i], 2606 session_close_single_x11, 0); 2607 } 2608 2609 /* Set up a suitable value for the DISPLAY variable. */ 2610 if (gethostname(hostname, sizeof(hostname)) < 0) 2611 fatal("gethostname: %.100s", strerror(errno)); 2612 /* 2613 * auth_display must be used as the displayname when the 2614 * authorization entry is added with xauth(1). This will be 2615 * different than the DISPLAY string for localhost displays. 2616 */ 2617 if (options.x11_use_localhost) { 2618 snprintf(display, sizeof display, "localhost:%u.%u", 2619 s->display_number, s->screen); 2620 snprintf(auth_display, sizeof auth_display, "unix:%u.%u", 2621 s->display_number, s->screen); 2622 s->display = xstrdup(display); 2623 s->auth_display = xstrdup(auth_display); 2624 } else { 2625 snprintf(display, sizeof display, "%.400s:%u.%u", hostname, 2626 s->display_number, s->screen); 2627 s->display = xstrdup(display); 2628 s->auth_display = xstrdup(display); 2629 } 2630 2631 return 1; 2632 } 2633 2634 static void 2635 do_authenticated2(Authctxt *authctxt) 2636 { 2637 server_loop2(authctxt); 2638 } 2639 2640 void 2641 do_cleanup(Authctxt *authctxt) 2642 { 2643 static int called = 0; 2644 2645 debug("do_cleanup"); 2646 2647 /* no cleanup if we're in the child for login shell */ 2648 if (is_child) 2649 return; 2650 2651 /* avoid double cleanup */ 2652 if (called) 2653 return; 2654 called = 1; 2655 2656 if (authctxt == NULL || !authctxt->authenticated) 2657 return; 2658 #ifdef KRB4 2659 if (options.kerberos_ticket_cleanup) 2660 krb4_cleanup_proc(authctxt); 2661 #endif 2662 #ifdef KRB5 2663 if (options.kerberos_ticket_cleanup && 2664 authctxt->krb5_ctx) 2665 krb5_cleanup_proc(authctxt); 2666 #endif 2667 2668 #ifdef GSSAPI 2669 if (compat20 && options.gss_cleanup_creds) 2670 ssh_gssapi_cleanup_creds(); 2671 #endif 2672 2673 #ifdef USE_PAM 2674 if (options.use_pam) { 2675 sshpam_cleanup(); 2676 sshpam_thread_cleanup(); 2677 } 2678 #endif 2679 2680 /* remove agent socket */ 2681 auth_sock_cleanup_proc(authctxt->pw); 2682 2683 /* 2684 * Cleanup ptys/utmp only if privsep is disabled, 2685 * or if running in monitor. 2686 */ 2687 if (!use_privsep || mm_is_monitor()) 2688 session_destroy_all(session_pty_cleanup2); 2689 } 2690 2691 /* Return a name for the remote host that fits inside utmp_size */ 2692 2693 const char * 2694 session_get_remote_name_or_ip(struct ssh *ssh, u_int utmp_size, int use_dns) 2695 { 2696 const char *remote = ""; 2697 2698 if (utmp_size > 0) 2699 remote = auth_get_canonical_hostname(ssh, use_dns); 2700 if (utmp_size == 0 || strlen(remote) > utmp_size) 2701 remote = ssh_remote_ipaddr(ssh); 2702 return remote; 2703 } 2704 2705