1 /* 2 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 3 * All rights reserved 4 * 5 * As far as I am concerned, the code I have written for this software 6 * can be used freely for any purpose. Any derived versions of this 7 * software must be clearly marked as such, and if the derived work is 8 * incompatible with the protocol description in the RFC file, it must be 9 * called by a name other than "ssh" or "Secure Shell". 10 * 11 * SSH2 support by Markus Friedl. 12 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 13 * 14 * Redistribution and use in source and binary forms, with or without 15 * modification, are permitted provided that the following conditions 16 * are met: 17 * 1. Redistributions of source code must retain the above copyright 18 * notice, this list of conditions and the following disclaimer. 19 * 2. Redistributions in binary form must reproduce the above copyright 20 * notice, this list of conditions and the following disclaimer in the 21 * documentation and/or other materials provided with the distribution. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 24 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 25 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 26 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 27 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 28 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 29 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 30 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 31 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 32 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 33 */ 34 35 #include "includes.h" 36 RCSID("$OpenBSD: session.c,v 1.181 2004/12/23 17:35:48 markus Exp $"); 37 38 #include "ssh.h" 39 #include "ssh1.h" 40 #include "ssh2.h" 41 #include "xmalloc.h" 42 #include "sshpty.h" 43 #include "packet.h" 44 #include "buffer.h" 45 #include "match.h" 46 #include "uidswap.h" 47 #include "compat.h" 48 #include "channels.h" 49 #include "bufaux.h" 50 #include "auth.h" 51 #include "auth-options.h" 52 #include "pathnames.h" 53 #include "log.h" 54 #include "servconf.h" 55 #include "sshlogin.h" 56 #include "serverloop.h" 57 #include "canohost.h" 58 #include "session.h" 59 #include "monitor_wrap.h" 60 61 #ifdef KRB5 62 #include <kafs.h> 63 #endif 64 65 #ifdef GSSAPI 66 #include "ssh-gss.h" 67 #endif 68 69 /* func */ 70 71 Session *session_new(void); 72 void session_set_fds(Session *, int, int, int); 73 void session_pty_cleanup(Session *); 74 void session_proctitle(Session *); 75 int session_setup_x11fwd(Session *); 76 void do_exec_pty(Session *, const char *); 77 void do_exec_no_pty(Session *, const char *); 78 void do_exec(Session *, const char *); 79 void do_login(Session *, const char *); 80 void do_child(Session *, const char *); 81 void do_motd(void); 82 int check_quietlogin(Session *, const char *); 83 84 static void do_authenticated1(Authctxt *); 85 static void do_authenticated2(Authctxt *); 86 87 static int session_pty_req(Session *); 88 89 /* import */ 90 extern ServerOptions options; 91 extern char *__progname; 92 extern int log_stderr; 93 extern int debug_flag; 94 extern u_int utmp_len; 95 extern int startup_pipe; 96 extern void destroy_sensitive_data(void); 97 extern Buffer loginmsg; 98 99 /* original command from peer. */ 100 const char *original_command = NULL; 101 102 /* data */ 103 #define MAX_SESSIONS 10 104 Session sessions[MAX_SESSIONS]; 105 106 #ifdef HAVE_LOGIN_CAP 107 login_cap_t *lc; 108 #endif 109 110 static int is_child = 0; 111 112 /* Name and directory of socket for authentication agent forwarding. */ 113 static char *auth_sock_name = NULL; 114 static char *auth_sock_dir = NULL; 115 116 /* removes the agent forwarding socket */ 117 118 static void 119 auth_sock_cleanup_proc(struct passwd *pw) 120 { 121 if (auth_sock_name != NULL) { 122 temporarily_use_uid(pw); 123 unlink(auth_sock_name); 124 rmdir(auth_sock_dir); 125 auth_sock_name = NULL; 126 restore_uid(); 127 } 128 } 129 130 static int 131 auth_input_request_forwarding(struct passwd * pw) 132 { 133 Channel *nc; 134 int sock; 135 struct sockaddr_un sunaddr; 136 137 if (auth_sock_name != NULL) { 138 error("authentication forwarding requested twice."); 139 return 0; 140 } 141 142 /* Temporarily drop privileged uid for mkdir/bind. */ 143 temporarily_use_uid(pw); 144 145 /* Allocate a buffer for the socket name, and format the name. */ 146 auth_sock_name = xmalloc(MAXPATHLEN); 147 auth_sock_dir = xmalloc(MAXPATHLEN); 148 strlcpy(auth_sock_dir, "/tmp/ssh-XXXXXXXXXX", MAXPATHLEN); 149 150 /* Create private directory for socket */ 151 if (mkdtemp(auth_sock_dir) == NULL) { 152 packet_send_debug("Agent forwarding disabled: " 153 "mkdtemp() failed: %.100s", strerror(errno)); 154 restore_uid(); 155 xfree(auth_sock_name); 156 xfree(auth_sock_dir); 157 auth_sock_name = NULL; 158 auth_sock_dir = NULL; 159 return 0; 160 } 161 snprintf(auth_sock_name, MAXPATHLEN, "%s/agent.%ld", 162 auth_sock_dir, (long) getpid()); 163 164 /* Create the socket. */ 165 sock = socket(AF_UNIX, SOCK_STREAM, 0); 166 if (sock < 0) 167 packet_disconnect("socket: %.100s", strerror(errno)); 168 169 /* Bind it to the name. */ 170 memset(&sunaddr, 0, sizeof(sunaddr)); 171 sunaddr.sun_family = AF_UNIX; 172 strlcpy(sunaddr.sun_path, auth_sock_name, sizeof(sunaddr.sun_path)); 173 174 if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) 175 packet_disconnect("bind: %.100s", strerror(errno)); 176 177 /* Restore the privileged uid. */ 178 restore_uid(); 179 180 /* Start listening on the socket. */ 181 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) 182 packet_disconnect("listen: %.100s", strerror(errno)); 183 184 /* Allocate a channel for the authentication agent socket. */ 185 nc = channel_new("auth socket", 186 SSH_CHANNEL_AUTH_SOCKET, sock, sock, -1, 187 CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 188 0, "auth socket", 1); 189 strlcpy(nc->path, auth_sock_name, sizeof(nc->path)); 190 return 1; 191 } 192 193 static void 194 display_loginmsg(void) 195 { 196 if (buffer_len(&loginmsg) > 0) { 197 buffer_append(&loginmsg, "\0", 1); 198 printf("%s", (char *)buffer_ptr(&loginmsg)); 199 buffer_clear(&loginmsg); 200 } 201 } 202 203 void 204 do_authenticated(Authctxt *authctxt) 205 { 206 setproctitle("%s", authctxt->pw->pw_name); 207 208 /* 209 * Cancel the alarm we set to limit the time taken for 210 * authentication. 211 */ 212 alarm(0); 213 if (startup_pipe != -1) { 214 close(startup_pipe); 215 startup_pipe = -1; 216 } 217 /* setup the channel layer */ 218 if (!no_port_forwarding_flag && options.allow_tcp_forwarding) 219 channel_permit_all_opens(); 220 221 if (compat20) 222 do_authenticated2(authctxt); 223 else 224 do_authenticated1(authctxt); 225 226 do_cleanup(authctxt); 227 } 228 229 /* 230 * Prepares for an interactive session. This is called after the user has 231 * been successfully authenticated. During this message exchange, pseudo 232 * terminals are allocated, X11, TCP/IP, and authentication agent forwardings 233 * are requested, etc. 234 */ 235 static void 236 do_authenticated1(Authctxt *authctxt) 237 { 238 Session *s; 239 char *command; 240 int success, type, screen_flag; 241 int enable_compression_after_reply = 0; 242 u_int proto_len, data_len, dlen, compression_level = 0; 243 244 s = session_new(); 245 if (s == NULL) { 246 error("no more sessions"); 247 return; 248 } 249 s->authctxt = authctxt; 250 s->pw = authctxt->pw; 251 252 /* 253 * We stay in this loop until the client requests to execute a shell 254 * or a command. 255 */ 256 for (;;) { 257 success = 0; 258 259 /* Get a packet from the client. */ 260 type = packet_read(); 261 262 /* Process the packet. */ 263 switch (type) { 264 case SSH_CMSG_REQUEST_COMPRESSION: 265 compression_level = packet_get_int(); 266 packet_check_eom(); 267 if (compression_level < 1 || compression_level > 9) { 268 packet_send_debug("Received invalid compression level %d.", 269 compression_level); 270 break; 271 } 272 if (!options.compression) { 273 debug2("compression disabled"); 274 break; 275 } 276 /* Enable compression after we have responded with SUCCESS. */ 277 enable_compression_after_reply = 1; 278 success = 1; 279 break; 280 281 case SSH_CMSG_REQUEST_PTY: 282 success = session_pty_req(s); 283 break; 284 285 case SSH_CMSG_X11_REQUEST_FORWARDING: 286 s->auth_proto = packet_get_string(&proto_len); 287 s->auth_data = packet_get_string(&data_len); 288 289 screen_flag = packet_get_protocol_flags() & 290 SSH_PROTOFLAG_SCREEN_NUMBER; 291 debug2("SSH_PROTOFLAG_SCREEN_NUMBER: %d", screen_flag); 292 293 if (packet_remaining() == 4) { 294 if (!screen_flag) 295 debug2("Buggy client: " 296 "X11 screen flag missing"); 297 s->screen = packet_get_int(); 298 } else { 299 s->screen = 0; 300 } 301 packet_check_eom(); 302 success = session_setup_x11fwd(s); 303 if (!success) { 304 xfree(s->auth_proto); 305 xfree(s->auth_data); 306 s->auth_proto = NULL; 307 s->auth_data = NULL; 308 } 309 break; 310 311 case SSH_CMSG_AGENT_REQUEST_FORWARDING: 312 if (no_agent_forwarding_flag || compat13) { 313 debug("Authentication agent forwarding not permitted for this authentication."); 314 break; 315 } 316 debug("Received authentication agent forwarding request."); 317 success = auth_input_request_forwarding(s->pw); 318 break; 319 320 case SSH_CMSG_PORT_FORWARD_REQUEST: 321 if (no_port_forwarding_flag) { 322 debug("Port forwarding not permitted for this authentication."); 323 break; 324 } 325 if (!options.allow_tcp_forwarding) { 326 debug("Port forwarding not permitted."); 327 break; 328 } 329 debug("Received TCP/IP port forwarding request."); 330 channel_input_port_forward_request(s->pw->pw_uid == 0, options.gateway_ports); 331 success = 1; 332 break; 333 334 case SSH_CMSG_MAX_PACKET_SIZE: 335 if (packet_set_maxsize(packet_get_int()) > 0) 336 success = 1; 337 break; 338 339 case SSH_CMSG_EXEC_SHELL: 340 case SSH_CMSG_EXEC_CMD: 341 if (type == SSH_CMSG_EXEC_CMD) { 342 command = packet_get_string(&dlen); 343 debug("Exec command '%.500s'", command); 344 do_exec(s, command); 345 xfree(command); 346 } else { 347 do_exec(s, NULL); 348 } 349 packet_check_eom(); 350 session_close(s); 351 return; 352 353 default: 354 /* 355 * Any unknown messages in this phase are ignored, 356 * and a failure message is returned. 357 */ 358 logit("Unknown packet type received after authentication: %d", type); 359 } 360 packet_start(success ? SSH_SMSG_SUCCESS : SSH_SMSG_FAILURE); 361 packet_send(); 362 packet_write_wait(); 363 364 /* Enable compression now that we have replied if appropriate. */ 365 if (enable_compression_after_reply) { 366 enable_compression_after_reply = 0; 367 packet_start_compression(compression_level); 368 } 369 } 370 } 371 372 /* 373 * This is called to fork and execute a command when we have no tty. This 374 * will call do_child from the child, and server_loop from the parent after 375 * setting up file descriptors and such. 376 */ 377 void 378 do_exec_no_pty(Session *s, const char *command) 379 { 380 pid_t pid; 381 382 #ifdef USE_PIPES 383 int pin[2], pout[2], perr[2]; 384 /* Allocate pipes for communicating with the program. */ 385 if (pipe(pin) < 0 || pipe(pout) < 0 || pipe(perr) < 0) 386 packet_disconnect("Could not create pipes: %.100s", 387 strerror(errno)); 388 #else /* USE_PIPES */ 389 int inout[2], err[2]; 390 /* Uses socket pairs to communicate with the program. */ 391 if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) < 0 || 392 socketpair(AF_UNIX, SOCK_STREAM, 0, err) < 0) 393 packet_disconnect("Could not create socket pairs: %.100s", 394 strerror(errno)); 395 #endif /* USE_PIPES */ 396 if (s == NULL) 397 fatal("do_exec_no_pty: no session"); 398 399 session_proctitle(s); 400 401 /* Fork the child. */ 402 if ((pid = fork()) == 0) { 403 is_child = 1; 404 405 /* Child. Reinitialize the log since the pid has changed. */ 406 log_init(__progname, options.log_level, options.log_facility, log_stderr); 407 408 /* 409 * Create a new session and process group since the 4.4BSD 410 * setlogin() affects the entire process group. 411 */ 412 if (setsid() < 0) 413 error("setsid failed: %.100s", strerror(errno)); 414 415 #ifdef USE_PIPES 416 /* 417 * Redirect stdin. We close the parent side of the socket 418 * pair, and make the child side the standard input. 419 */ 420 close(pin[1]); 421 if (dup2(pin[0], 0) < 0) 422 perror("dup2 stdin"); 423 close(pin[0]); 424 425 /* Redirect stdout. */ 426 close(pout[0]); 427 if (dup2(pout[1], 1) < 0) 428 perror("dup2 stdout"); 429 close(pout[1]); 430 431 /* Redirect stderr. */ 432 close(perr[0]); 433 if (dup2(perr[1], 2) < 0) 434 perror("dup2 stderr"); 435 close(perr[1]); 436 #else /* USE_PIPES */ 437 /* 438 * Redirect stdin, stdout, and stderr. Stdin and stdout will 439 * use the same socket, as some programs (particularly rdist) 440 * seem to depend on it. 441 */ 442 close(inout[1]); 443 close(err[1]); 444 if (dup2(inout[0], 0) < 0) /* stdin */ 445 perror("dup2 stdin"); 446 if (dup2(inout[0], 1) < 0) /* stdout. Note: same socket as stdin. */ 447 perror("dup2 stdout"); 448 if (dup2(err[0], 2) < 0) /* stderr */ 449 perror("dup2 stderr"); 450 #endif /* USE_PIPES */ 451 452 /* Do processing for the child (exec command etc). */ 453 do_child(s, command); 454 /* NOTREACHED */ 455 } 456 if (pid < 0) 457 packet_disconnect("fork failed: %.100s", strerror(errno)); 458 s->pid = pid; 459 /* Set interactive/non-interactive mode. */ 460 packet_set_interactive(s->display != NULL); 461 #ifdef USE_PIPES 462 /* We are the parent. Close the child sides of the pipes. */ 463 close(pin[0]); 464 close(pout[1]); 465 close(perr[1]); 466 467 if (compat20) { 468 if (s->is_subsystem) { 469 close(perr[0]); 470 perr[0] = -1; 471 } 472 session_set_fds(s, pin[1], pout[0], perr[0]); 473 } else { 474 /* Enter the interactive session. */ 475 server_loop(pid, pin[1], pout[0], perr[0]); 476 /* server_loop has closed pin[1], pout[0], and perr[0]. */ 477 } 478 #else /* USE_PIPES */ 479 /* We are the parent. Close the child sides of the socket pairs. */ 480 close(inout[0]); 481 close(err[0]); 482 483 /* 484 * Enter the interactive session. Note: server_loop must be able to 485 * handle the case that fdin and fdout are the same. 486 */ 487 if (compat20) { 488 session_set_fds(s, inout[1], inout[1], s->is_subsystem ? -1 : err[1]); 489 } else { 490 server_loop(pid, inout[1], inout[1], err[1]); 491 /* server_loop has closed inout[1] and err[1]. */ 492 } 493 #endif /* USE_PIPES */ 494 } 495 496 /* 497 * This is called to fork and execute a command when we have a tty. This 498 * will call do_child from the child, and server_loop from the parent after 499 * setting up file descriptors, controlling tty, updating wtmp, utmp, 500 * lastlog, and other such operations. 501 */ 502 void 503 do_exec_pty(Session *s, const char *command) 504 { 505 int fdout, ptyfd, ttyfd, ptymaster; 506 pid_t pid; 507 508 if (s == NULL) 509 fatal("do_exec_pty: no session"); 510 ptyfd = s->ptyfd; 511 ttyfd = s->ttyfd; 512 513 /* Fork the child. */ 514 if ((pid = fork()) == 0) { 515 is_child = 1; 516 517 /* Child. Reinitialize the log because the pid has changed. */ 518 log_init(__progname, options.log_level, options.log_facility, log_stderr); 519 /* Close the master side of the pseudo tty. */ 520 close(ptyfd); 521 522 /* Make the pseudo tty our controlling tty. */ 523 pty_make_controlling_tty(&ttyfd, s->tty); 524 525 /* Redirect stdin/stdout/stderr from the pseudo tty. */ 526 if (dup2(ttyfd, 0) < 0) 527 error("dup2 stdin: %s", strerror(errno)); 528 if (dup2(ttyfd, 1) < 0) 529 error("dup2 stdout: %s", strerror(errno)); 530 if (dup2(ttyfd, 2) < 0) 531 error("dup2 stderr: %s", strerror(errno)); 532 533 /* Close the extra descriptor for the pseudo tty. */ 534 close(ttyfd); 535 536 /* record login, etc. similar to login(1) */ 537 if (!(options.use_login && command == NULL)) 538 do_login(s, command); 539 540 /* Do common processing for the child, such as execing the command. */ 541 do_child(s, command); 542 /* NOTREACHED */ 543 } 544 if (pid < 0) 545 packet_disconnect("fork failed: %.100s", strerror(errno)); 546 s->pid = pid; 547 548 /* Parent. Close the slave side of the pseudo tty. */ 549 close(ttyfd); 550 551 /* 552 * Create another descriptor of the pty master side for use as the 553 * standard input. We could use the original descriptor, but this 554 * simplifies code in server_loop. The descriptor is bidirectional. 555 */ 556 fdout = dup(ptyfd); 557 if (fdout < 0) 558 packet_disconnect("dup #1 failed: %.100s", strerror(errno)); 559 560 /* we keep a reference to the pty master */ 561 ptymaster = dup(ptyfd); 562 if (ptymaster < 0) 563 packet_disconnect("dup #2 failed: %.100s", strerror(errno)); 564 s->ptymaster = ptymaster; 565 566 /* Enter interactive session. */ 567 packet_set_interactive(1); 568 if (compat20) { 569 session_set_fds(s, ptyfd, fdout, -1); 570 } else { 571 server_loop(pid, ptyfd, fdout, -1); 572 /* server_loop _has_ closed ptyfd and fdout. */ 573 } 574 } 575 576 /* 577 * This is called to fork and execute a command. If another command is 578 * to be forced, execute that instead. 579 */ 580 void 581 do_exec(Session *s, const char *command) 582 { 583 if (forced_command) { 584 original_command = command; 585 command = forced_command; 586 debug("Forced command '%.900s'", command); 587 } 588 589 #ifdef GSSAPI 590 if (options.gss_authentication) { 591 temporarily_use_uid(s->pw); 592 ssh_gssapi_storecreds(); 593 restore_uid(); 594 } 595 #endif 596 597 if (s->ttyfd != -1) 598 do_exec_pty(s, command); 599 else 600 do_exec_no_pty(s, command); 601 602 original_command = NULL; 603 604 /* 605 * Clear loginmsg: it's the child's responsibility to display 606 * it to the user, otherwise multiple sessions may accumulate 607 * multiple copies of the login messages. 608 */ 609 buffer_clear(&loginmsg); 610 } 611 612 613 /* administrative, login(1)-like work */ 614 void 615 do_login(Session *s, const char *command) 616 { 617 socklen_t fromlen; 618 struct sockaddr_storage from; 619 struct passwd * pw = s->pw; 620 pid_t pid = getpid(); 621 622 /* 623 * Get IP address of client. If the connection is not a socket, let 624 * the address be 0.0.0.0. 625 */ 626 memset(&from, 0, sizeof(from)); 627 fromlen = sizeof(from); 628 if (packet_connection_is_on_socket()) { 629 if (getpeername(packet_get_connection_in(), 630 (struct sockaddr *) & from, &fromlen) < 0) { 631 debug("getpeername: %.100s", strerror(errno)); 632 cleanup_exit(255); 633 } 634 } 635 636 /* Record that there was a login on that tty from the remote host. */ 637 if (!use_privsep) 638 record_login(pid, s->tty, pw->pw_name, pw->pw_uid, 639 get_remote_name_or_ip(utmp_len, 640 options.use_dns), 641 (struct sockaddr *)&from, fromlen); 642 643 if (check_quietlogin(s, command)) 644 return; 645 646 display_loginmsg(); 647 648 do_motd(); 649 } 650 651 /* 652 * Display the message of the day. 653 */ 654 void 655 do_motd(void) 656 { 657 FILE *f; 658 char buf[256]; 659 660 if (options.print_motd) { 661 #ifdef HAVE_LOGIN_CAP 662 f = fopen(login_getcapstr(lc, "welcome", "/etc/motd", 663 "/etc/motd"), "r"); 664 #else 665 f = fopen("/etc/motd", "r"); 666 #endif 667 if (f) { 668 while (fgets(buf, sizeof(buf), f)) 669 fputs(buf, stdout); 670 fclose(f); 671 } 672 } 673 } 674 675 676 /* 677 * Check for quiet login, either .hushlogin or command given. 678 */ 679 int 680 check_quietlogin(Session *s, const char *command) 681 { 682 char buf[256]; 683 struct passwd *pw = s->pw; 684 struct stat st; 685 686 /* Return 1 if .hushlogin exists or a command given. */ 687 if (command != NULL) 688 return 1; 689 snprintf(buf, sizeof(buf), "%.200s/.hushlogin", pw->pw_dir); 690 #ifdef HAVE_LOGIN_CAP 691 if (login_getcapbool(lc, "hushlogin", 0) || stat(buf, &st) >= 0) 692 return 1; 693 #else 694 if (stat(buf, &st) >= 0) 695 return 1; 696 #endif 697 return 0; 698 } 699 700 /* 701 * Sets the value of the given variable in the environment. If the variable 702 * already exists, its value is overriden. 703 */ 704 void 705 child_set_env(char ***envp, u_int *envsizep, const char *name, 706 const char *value) 707 { 708 char **env; 709 u_int envsize; 710 u_int i, namelen; 711 712 /* 713 * Find the slot where the value should be stored. If the variable 714 * already exists, we reuse the slot; otherwise we append a new slot 715 * at the end of the array, expanding if necessary. 716 */ 717 env = *envp; 718 namelen = strlen(name); 719 for (i = 0; env[i]; i++) 720 if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=') 721 break; 722 if (env[i]) { 723 /* Reuse the slot. */ 724 xfree(env[i]); 725 } else { 726 /* New variable. Expand if necessary. */ 727 envsize = *envsizep; 728 if (i >= envsize - 1) { 729 if (envsize >= 1000) 730 fatal("child_set_env: too many env vars"); 731 envsize += 50; 732 env = (*envp) = xrealloc(env, envsize * sizeof(char *)); 733 *envsizep = envsize; 734 } 735 /* Need to set the NULL pointer at end of array beyond the new slot. */ 736 env[i + 1] = NULL; 737 } 738 739 /* Allocate space and format the variable in the appropriate slot. */ 740 env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1); 741 snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value); 742 } 743 744 /* 745 * Reads environment variables from the given file and adds/overrides them 746 * into the environment. If the file does not exist, this does nothing. 747 * Otherwise, it must consist of empty lines, comments (line starts with '#') 748 * and assignments of the form name=value. No other forms are allowed. 749 */ 750 static void 751 read_environment_file(char ***env, u_int *envsize, 752 const char *filename) 753 { 754 FILE *f; 755 char buf[4096]; 756 char *cp, *value; 757 u_int lineno = 0; 758 759 f = fopen(filename, "r"); 760 if (!f) 761 return; 762 763 while (fgets(buf, sizeof(buf), f)) { 764 if (++lineno > 1000) 765 fatal("Too many lines in environment file %s", filename); 766 for (cp = buf; *cp == ' ' || *cp == '\t'; cp++) 767 ; 768 if (!*cp || *cp == '#' || *cp == '\n') 769 continue; 770 if (strchr(cp, '\n')) 771 *strchr(cp, '\n') = '\0'; 772 value = strchr(cp, '='); 773 if (value == NULL) { 774 fprintf(stderr, "Bad line %u in %.100s\n", lineno, 775 filename); 776 continue; 777 } 778 /* 779 * Replace the equals sign by nul, and advance value to 780 * the value string. 781 */ 782 *value = '\0'; 783 value++; 784 child_set_env(env, envsize, cp, value); 785 } 786 fclose(f); 787 } 788 789 static char ** 790 do_setup_env(Session *s, const char *shell) 791 { 792 char buf[256]; 793 u_int i, envsize; 794 char **env, *laddr; 795 struct passwd *pw = s->pw; 796 797 /* Initialize the environment. */ 798 envsize = 100; 799 env = xmalloc(envsize * sizeof(char *)); 800 env[0] = NULL; 801 802 #ifdef GSSAPI 803 /* Allow any GSSAPI methods that we've used to alter 804 * the childs environment as they see fit 805 */ 806 ssh_gssapi_do_child(&env, &envsize); 807 #endif 808 809 if (!options.use_login) { 810 /* Set basic environment. */ 811 for (i = 0; i < s->num_env; i++) 812 child_set_env(&env, &envsize, s->env[i].name, 813 s->env[i].val); 814 815 child_set_env(&env, &envsize, "USER", pw->pw_name); 816 child_set_env(&env, &envsize, "LOGNAME", pw->pw_name); 817 child_set_env(&env, &envsize, "HOME", pw->pw_dir); 818 #ifdef HAVE_LOGIN_CAP 819 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETPATH) < 0) 820 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); 821 else 822 child_set_env(&env, &envsize, "PATH", getenv("PATH")); 823 #else 824 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); 825 #endif 826 827 snprintf(buf, sizeof buf, "%.200s/%.50s", 828 _PATH_MAILDIR, pw->pw_name); 829 child_set_env(&env, &envsize, "MAIL", buf); 830 831 /* Normal systems set SHELL by default. */ 832 child_set_env(&env, &envsize, "SHELL", shell); 833 } 834 if (getenv("TZ")) 835 child_set_env(&env, &envsize, "TZ", getenv("TZ")); 836 837 /* Set custom environment options from RSA authentication. */ 838 if (!options.use_login) { 839 while (custom_environment) { 840 struct envstring *ce = custom_environment; 841 char *str = ce->s; 842 843 for (i = 0; str[i] != '=' && str[i]; i++) 844 ; 845 if (str[i] == '=') { 846 str[i] = 0; 847 child_set_env(&env, &envsize, str, str + i + 1); 848 } 849 custom_environment = ce->next; 850 xfree(ce->s); 851 xfree(ce); 852 } 853 } 854 855 /* SSH_CLIENT deprecated */ 856 snprintf(buf, sizeof buf, "%.50s %d %d", 857 get_remote_ipaddr(), get_remote_port(), get_local_port()); 858 child_set_env(&env, &envsize, "SSH_CLIENT", buf); 859 860 laddr = get_local_ipaddr(packet_get_connection_in()); 861 snprintf(buf, sizeof buf, "%.50s %d %.50s %d", 862 get_remote_ipaddr(), get_remote_port(), laddr, get_local_port()); 863 xfree(laddr); 864 child_set_env(&env, &envsize, "SSH_CONNECTION", buf); 865 866 if (s->ttyfd != -1) 867 child_set_env(&env, &envsize, "SSH_TTY", s->tty); 868 if (s->term) 869 child_set_env(&env, &envsize, "TERM", s->term); 870 if (s->display) 871 child_set_env(&env, &envsize, "DISPLAY", s->display); 872 if (original_command) 873 child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND", 874 original_command); 875 #ifdef KRB5 876 if (s->authctxt->krb5_ticket_file) 877 child_set_env(&env, &envsize, "KRB5CCNAME", 878 s->authctxt->krb5_ticket_file); 879 #endif 880 if (auth_sock_name != NULL) 881 child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME, 882 auth_sock_name); 883 884 /* read $HOME/.ssh/environment. */ 885 if (options.permit_user_env && !options.use_login) { 886 snprintf(buf, sizeof buf, "%.200s/.ssh/environment", 887 pw->pw_dir); 888 read_environment_file(&env, &envsize, buf); 889 } 890 if (debug_flag) { 891 /* dump the environment */ 892 fprintf(stderr, "Environment:\n"); 893 for (i = 0; env[i]; i++) 894 fprintf(stderr, " %.200s\n", env[i]); 895 } 896 return env; 897 } 898 899 /* 900 * Run $HOME/.ssh/rc, /etc/ssh/sshrc, or xauth (whichever is found 901 * first in this order). 902 */ 903 static void 904 do_rc_files(Session *s, const char *shell) 905 { 906 FILE *f = NULL; 907 char cmd[1024]; 908 int do_xauth; 909 struct stat st; 910 911 do_xauth = 912 s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL; 913 914 /* ignore _PATH_SSH_USER_RC for subsystems */ 915 if (!s->is_subsystem && (stat(_PATH_SSH_USER_RC, &st) >= 0)) { 916 snprintf(cmd, sizeof cmd, "%s -c '%s %s'", 917 shell, _PATH_BSHELL, _PATH_SSH_USER_RC); 918 if (debug_flag) 919 fprintf(stderr, "Running %s\n", cmd); 920 f = popen(cmd, "w"); 921 if (f) { 922 if (do_xauth) 923 fprintf(f, "%s %s\n", s->auth_proto, 924 s->auth_data); 925 pclose(f); 926 } else 927 fprintf(stderr, "Could not run %s\n", 928 _PATH_SSH_USER_RC); 929 } else if (stat(_PATH_SSH_SYSTEM_RC, &st) >= 0) { 930 if (debug_flag) 931 fprintf(stderr, "Running %s %s\n", _PATH_BSHELL, 932 _PATH_SSH_SYSTEM_RC); 933 f = popen(_PATH_BSHELL " " _PATH_SSH_SYSTEM_RC, "w"); 934 if (f) { 935 if (do_xauth) 936 fprintf(f, "%s %s\n", s->auth_proto, 937 s->auth_data); 938 pclose(f); 939 } else 940 fprintf(stderr, "Could not run %s\n", 941 _PATH_SSH_SYSTEM_RC); 942 } else if (do_xauth && options.xauth_location != NULL) { 943 /* Add authority data to .Xauthority if appropriate. */ 944 if (debug_flag) { 945 fprintf(stderr, 946 "Running %.500s remove %.100s\n", 947 options.xauth_location, s->auth_display); 948 fprintf(stderr, 949 "%.500s add %.100s %.100s %.100s\n", 950 options.xauth_location, s->auth_display, 951 s->auth_proto, s->auth_data); 952 } 953 snprintf(cmd, sizeof cmd, "%s -q -", 954 options.xauth_location); 955 f = popen(cmd, "w"); 956 if (f) { 957 fprintf(f, "remove %s\n", 958 s->auth_display); 959 fprintf(f, "add %s %s %s\n", 960 s->auth_display, s->auth_proto, 961 s->auth_data); 962 pclose(f); 963 } else { 964 fprintf(stderr, "Could not run %s\n", 965 cmd); 966 } 967 } 968 } 969 970 static void 971 do_nologin(struct passwd *pw) 972 { 973 FILE *f = NULL; 974 char buf[1024]; 975 976 #ifdef HAVE_LOGIN_CAP 977 if (!login_getcapbool(lc, "ignorenologin", 0) && pw->pw_uid) 978 f = fopen(login_getcapstr(lc, "nologin", _PATH_NOLOGIN, 979 _PATH_NOLOGIN), "r"); 980 #else 981 if (pw->pw_uid) 982 f = fopen(_PATH_NOLOGIN, "r"); 983 #endif 984 if (f) { 985 /* /etc/nologin exists. Print its contents and exit. */ 986 logit("User %.100s not allowed because %s exists", 987 pw->pw_name, _PATH_NOLOGIN); 988 while (fgets(buf, sizeof(buf), f)) 989 fputs(buf, stderr); 990 fclose(f); 991 exit(254); 992 } 993 } 994 995 /* Set login name, uid, gid, and groups. */ 996 void 997 do_setusercontext(struct passwd *pw) 998 { 999 if (getuid() == 0 || geteuid() == 0) { 1000 #ifdef HAVE_LOGIN_CAP 1001 if (setusercontext(lc, pw, pw->pw_uid, 1002 (LOGIN_SETALL & ~LOGIN_SETPATH)) < 0) { 1003 perror("unable to set user context"); 1004 exit(1); 1005 } 1006 #else 1007 if (setlogin(pw->pw_name) < 0) 1008 error("setlogin failed: %s", strerror(errno)); 1009 if (setgid(pw->pw_gid) < 0) { 1010 perror("setgid"); 1011 exit(1); 1012 } 1013 /* Initialize the group list. */ 1014 if (initgroups(pw->pw_name, pw->pw_gid) < 0) { 1015 perror("initgroups"); 1016 exit(1); 1017 } 1018 endgrent(); 1019 1020 /* Permanently switch to the desired uid. */ 1021 permanently_set_uid(pw); 1022 #endif 1023 } 1024 if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) 1025 fatal("Failed to set uids to %u.", (u_int) pw->pw_uid); 1026 } 1027 1028 static void 1029 do_pwchange(Session *s) 1030 { 1031 fflush(NULL); 1032 fprintf(stderr, "WARNING: Your password has expired.\n"); 1033 if (s->ttyfd != -1) { 1034 fprintf(stderr, 1035 "You must change your password now and login again!\n"); 1036 execl(_PATH_PASSWD_PROG, "passwd", (char *)NULL); 1037 perror("passwd"); 1038 } else { 1039 fprintf(stderr, 1040 "Password change required but no TTY available.\n"); 1041 } 1042 exit(1); 1043 } 1044 1045 static void 1046 launch_login(struct passwd *pw, const char *hostname) 1047 { 1048 /* Launch login(1). */ 1049 1050 execl("/usr/bin/login", "login", "-h", hostname, 1051 "-p", "-f", "--", pw->pw_name, (char *)NULL); 1052 1053 /* Login couldn't be executed, die. */ 1054 1055 perror("login"); 1056 exit(1); 1057 } 1058 1059 static void 1060 child_close_fds(void) 1061 { 1062 int i; 1063 1064 if (packet_get_connection_in() == packet_get_connection_out()) 1065 close(packet_get_connection_in()); 1066 else { 1067 close(packet_get_connection_in()); 1068 close(packet_get_connection_out()); 1069 } 1070 /* 1071 * Close all descriptors related to channels. They will still remain 1072 * open in the parent. 1073 */ 1074 /* XXX better use close-on-exec? -markus */ 1075 channel_close_all(); 1076 1077 /* 1078 * Close any extra file descriptors. Note that there may still be 1079 * descriptors left by system functions. They will be closed later. 1080 */ 1081 endpwent(); 1082 1083 /* 1084 * Close any extra open file descriptors so that we don\'t have them 1085 * hanging around in clients. Note that we want to do this after 1086 * initgroups, because at least on Solaris 2.3 it leaves file 1087 * descriptors open. 1088 */ 1089 for (i = 3; i < 64; i++) 1090 close(i); 1091 } 1092 1093 /* 1094 * Performs common processing for the child, such as setting up the 1095 * environment, closing extra file descriptors, setting the user and group 1096 * ids, and executing the command or shell. 1097 */ 1098 void 1099 do_child(Session *s, const char *command) 1100 { 1101 extern char **environ; 1102 char **env; 1103 char *argv[10]; 1104 const char *shell, *shell0, *hostname = NULL; 1105 struct passwd *pw = s->pw; 1106 1107 /* remove hostkey from the child's memory */ 1108 destroy_sensitive_data(); 1109 1110 /* Force a password change */ 1111 if (s->authctxt->force_pwchange) { 1112 do_setusercontext(pw); 1113 child_close_fds(); 1114 do_pwchange(s); 1115 exit(1); 1116 } 1117 1118 /* login(1) is only called if we execute the login shell */ 1119 if (options.use_login && command != NULL) 1120 options.use_login = 0; 1121 1122 /* 1123 * Login(1) does this as well, and it needs uid 0 for the "-h" 1124 * switch, so we let login(1) to this for us. 1125 */ 1126 if (!options.use_login) { 1127 do_nologin(pw); 1128 do_setusercontext(pw); 1129 } 1130 1131 /* 1132 * Get the shell from the password data. An empty shell field is 1133 * legal, and means /bin/sh. 1134 */ 1135 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; 1136 1137 /* 1138 * Make sure $SHELL points to the shell from the password file, 1139 * even if shell is overridden from login.conf 1140 */ 1141 env = do_setup_env(s, shell); 1142 1143 #ifdef HAVE_LOGIN_CAP 1144 shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell); 1145 #endif 1146 1147 /* we have to stash the hostname before we close our socket. */ 1148 if (options.use_login) 1149 hostname = get_remote_name_or_ip(utmp_len, 1150 options.use_dns); 1151 /* 1152 * Close the connection descriptors; note that this is the child, and 1153 * the server will still have the socket open, and it is important 1154 * that we do not shutdown it. Note that the descriptors cannot be 1155 * closed before building the environment, as we call 1156 * get_remote_ipaddr there. 1157 */ 1158 child_close_fds(); 1159 1160 /* 1161 * Must take new environment into use so that .ssh/rc, 1162 * /etc/ssh/sshrc and xauth are run in the proper environment. 1163 */ 1164 environ = env; 1165 1166 #ifdef KRB5 1167 /* 1168 * At this point, we check to see if AFS is active and if we have 1169 * a valid Kerberos 5 TGT. If so, it seems like a good idea to see 1170 * if we can (and need to) extend the ticket into an AFS token. If 1171 * we don't do this, we run into potential problems if the user's 1172 * home directory is in AFS and it's not world-readable. 1173 */ 1174 1175 if (options.kerberos_get_afs_token && k_hasafs() && 1176 (s->authctxt->krb5_ctx != NULL)) { 1177 char cell[64]; 1178 1179 debug("Getting AFS token"); 1180 1181 k_setpag(); 1182 1183 if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0) 1184 krb5_afslog(s->authctxt->krb5_ctx, 1185 s->authctxt->krb5_fwd_ccache, cell, NULL); 1186 1187 krb5_afslog_home(s->authctxt->krb5_ctx, 1188 s->authctxt->krb5_fwd_ccache, NULL, NULL, pw->pw_dir); 1189 } 1190 #endif 1191 1192 /* Change current directory to the user\'s home directory. */ 1193 if (chdir(pw->pw_dir) < 0) { 1194 fprintf(stderr, "Could not chdir to home directory %s: %s\n", 1195 pw->pw_dir, strerror(errno)); 1196 #ifdef HAVE_LOGIN_CAP 1197 if (login_getcapbool(lc, "requirehome", 0)) 1198 exit(1); 1199 #endif 1200 } 1201 1202 if (!options.use_login) 1203 do_rc_files(s, shell); 1204 1205 /* restore SIGPIPE for child */ 1206 signal(SIGPIPE, SIG_DFL); 1207 1208 if (options.use_login) { 1209 launch_login(pw, hostname); 1210 /* NEVERREACHED */ 1211 } 1212 1213 /* Get the last component of the shell name. */ 1214 if ((shell0 = strrchr(shell, '/')) != NULL) 1215 shell0++; 1216 else 1217 shell0 = shell; 1218 1219 /* 1220 * If we have no command, execute the shell. In this case, the shell 1221 * name to be passed in argv[0] is preceded by '-' to indicate that 1222 * this is a login shell. 1223 */ 1224 if (!command) { 1225 char argv0[256]; 1226 1227 /* Start the shell. Set initial character to '-'. */ 1228 argv0[0] = '-'; 1229 1230 if (strlcpy(argv0 + 1, shell0, sizeof(argv0) - 1) 1231 >= sizeof(argv0) - 1) { 1232 errno = EINVAL; 1233 perror(shell); 1234 exit(1); 1235 } 1236 1237 /* Execute the shell. */ 1238 argv[0] = argv0; 1239 argv[1] = NULL; 1240 execve(shell, argv, env); 1241 1242 /* Executing the shell failed. */ 1243 perror(shell); 1244 exit(1); 1245 } 1246 /* 1247 * Execute the command using the user's shell. This uses the -c 1248 * option to execute the command. 1249 */ 1250 argv[0] = (char *) shell0; 1251 argv[1] = "-c"; 1252 argv[2] = (char *) command; 1253 argv[3] = NULL; 1254 execve(shell, argv, env); 1255 perror(shell); 1256 exit(1); 1257 } 1258 1259 Session * 1260 session_new(void) 1261 { 1262 int i; 1263 static int did_init = 0; 1264 if (!did_init) { 1265 debug("session_new: init"); 1266 for (i = 0; i < MAX_SESSIONS; i++) { 1267 sessions[i].used = 0; 1268 } 1269 did_init = 1; 1270 } 1271 for (i = 0; i < MAX_SESSIONS; i++) { 1272 Session *s = &sessions[i]; 1273 if (! s->used) { 1274 memset(s, 0, sizeof(*s)); 1275 s->chanid = -1; 1276 s->ptyfd = -1; 1277 s->ttyfd = -1; 1278 s->used = 1; 1279 s->self = i; 1280 debug("session_new: session %d", i); 1281 return s; 1282 } 1283 } 1284 return NULL; 1285 } 1286 1287 static void 1288 session_dump(void) 1289 { 1290 int i; 1291 for (i = 0; i < MAX_SESSIONS; i++) { 1292 Session *s = &sessions[i]; 1293 debug("dump: used %d session %d %p channel %d pid %ld", 1294 s->used, 1295 s->self, 1296 s, 1297 s->chanid, 1298 (long)s->pid); 1299 } 1300 } 1301 1302 int 1303 session_open(Authctxt *authctxt, int chanid) 1304 { 1305 Session *s = session_new(); 1306 debug("session_open: channel %d", chanid); 1307 if (s == NULL) { 1308 error("no more sessions"); 1309 return 0; 1310 } 1311 s->authctxt = authctxt; 1312 s->pw = authctxt->pw; 1313 if (s->pw == NULL || !authctxt->valid) 1314 fatal("no user for session %d", s->self); 1315 debug("session_open: session %d: link with channel %d", s->self, chanid); 1316 s->chanid = chanid; 1317 return 1; 1318 } 1319 1320 Session * 1321 session_by_tty(char *tty) 1322 { 1323 int i; 1324 for (i = 0; i < MAX_SESSIONS; i++) { 1325 Session *s = &sessions[i]; 1326 if (s->used && s->ttyfd != -1 && strcmp(s->tty, tty) == 0) { 1327 debug("session_by_tty: session %d tty %s", i, tty); 1328 return s; 1329 } 1330 } 1331 debug("session_by_tty: unknown tty %.100s", tty); 1332 session_dump(); 1333 return NULL; 1334 } 1335 1336 static Session * 1337 session_by_channel(int id) 1338 { 1339 int i; 1340 for (i = 0; i < MAX_SESSIONS; i++) { 1341 Session *s = &sessions[i]; 1342 if (s->used && s->chanid == id) { 1343 debug("session_by_channel: session %d channel %d", i, id); 1344 return s; 1345 } 1346 } 1347 debug("session_by_channel: unknown channel %d", id); 1348 session_dump(); 1349 return NULL; 1350 } 1351 1352 static Session * 1353 session_by_pid(pid_t pid) 1354 { 1355 int i; 1356 debug("session_by_pid: pid %ld", (long)pid); 1357 for (i = 0; i < MAX_SESSIONS; i++) { 1358 Session *s = &sessions[i]; 1359 if (s->used && s->pid == pid) 1360 return s; 1361 } 1362 error("session_by_pid: unknown pid %ld", (long)pid); 1363 session_dump(); 1364 return NULL; 1365 } 1366 1367 static int 1368 session_window_change_req(Session *s) 1369 { 1370 s->col = packet_get_int(); 1371 s->row = packet_get_int(); 1372 s->xpixel = packet_get_int(); 1373 s->ypixel = packet_get_int(); 1374 packet_check_eom(); 1375 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 1376 return 1; 1377 } 1378 1379 static int 1380 session_pty_req(Session *s) 1381 { 1382 u_int len; 1383 int n_bytes; 1384 1385 if (no_pty_flag) { 1386 debug("Allocating a pty not permitted for this authentication."); 1387 return 0; 1388 } 1389 if (s->ttyfd != -1) { 1390 packet_disconnect("Protocol error: you already have a pty."); 1391 return 0; 1392 } 1393 1394 s->term = packet_get_string(&len); 1395 1396 if (compat20) { 1397 s->col = packet_get_int(); 1398 s->row = packet_get_int(); 1399 } else { 1400 s->row = packet_get_int(); 1401 s->col = packet_get_int(); 1402 } 1403 s->xpixel = packet_get_int(); 1404 s->ypixel = packet_get_int(); 1405 1406 if (strcmp(s->term, "") == 0) { 1407 xfree(s->term); 1408 s->term = NULL; 1409 } 1410 1411 /* Allocate a pty and open it. */ 1412 debug("Allocating pty."); 1413 if (!PRIVSEP(pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty)))) { 1414 if (s->term) 1415 xfree(s->term); 1416 s->term = NULL; 1417 s->ptyfd = -1; 1418 s->ttyfd = -1; 1419 error("session_pty_req: session %d alloc failed", s->self); 1420 return 0; 1421 } 1422 debug("session_pty_req: session %d alloc %s", s->self, s->tty); 1423 1424 /* for SSH1 the tty modes length is not given */ 1425 if (!compat20) 1426 n_bytes = packet_remaining(); 1427 tty_parse_modes(s->ttyfd, &n_bytes); 1428 1429 if (!use_privsep) 1430 pty_setowner(s->pw, s->tty); 1431 1432 /* Set window size from the packet. */ 1433 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 1434 1435 packet_check_eom(); 1436 session_proctitle(s); 1437 return 1; 1438 } 1439 1440 static int 1441 session_subsystem_req(Session *s) 1442 { 1443 struct stat st; 1444 u_int len; 1445 int success = 0; 1446 char *cmd, *subsys = packet_get_string(&len); 1447 int i; 1448 1449 packet_check_eom(); 1450 logit("subsystem request for %.100s", subsys); 1451 1452 for (i = 0; i < options.num_subsystems; i++) { 1453 if (strcmp(subsys, options.subsystem_name[i]) == 0) { 1454 cmd = options.subsystem_command[i]; 1455 if (stat(cmd, &st) < 0) { 1456 error("subsystem: cannot stat %s: %s", cmd, 1457 strerror(errno)); 1458 break; 1459 } 1460 debug("subsystem: exec() %s", cmd); 1461 s->is_subsystem = 1; 1462 do_exec(s, cmd); 1463 success = 1; 1464 break; 1465 } 1466 } 1467 1468 if (!success) 1469 logit("subsystem request for %.100s failed, subsystem not found", 1470 subsys); 1471 1472 xfree(subsys); 1473 return success; 1474 } 1475 1476 static int 1477 session_x11_req(Session *s) 1478 { 1479 int success; 1480 1481 s->single_connection = packet_get_char(); 1482 s->auth_proto = packet_get_string(NULL); 1483 s->auth_data = packet_get_string(NULL); 1484 s->screen = packet_get_int(); 1485 packet_check_eom(); 1486 1487 success = session_setup_x11fwd(s); 1488 if (!success) { 1489 xfree(s->auth_proto); 1490 xfree(s->auth_data); 1491 s->auth_proto = NULL; 1492 s->auth_data = NULL; 1493 } 1494 return success; 1495 } 1496 1497 static int 1498 session_shell_req(Session *s) 1499 { 1500 packet_check_eom(); 1501 do_exec(s, NULL); 1502 return 1; 1503 } 1504 1505 static int 1506 session_exec_req(Session *s) 1507 { 1508 u_int len; 1509 char *command = packet_get_string(&len); 1510 packet_check_eom(); 1511 do_exec(s, command); 1512 xfree(command); 1513 return 1; 1514 } 1515 1516 static int 1517 session_break_req(Session *s) 1518 { 1519 1520 packet_get_int(); /* ignored */ 1521 packet_check_eom(); 1522 1523 if (s->ttyfd == -1 || 1524 tcsendbreak(s->ttyfd, 0) < 0) 1525 return 0; 1526 return 1; 1527 } 1528 1529 static int 1530 session_env_req(Session *s) 1531 { 1532 char *name, *val; 1533 u_int name_len, val_len, i; 1534 1535 name = packet_get_string(&name_len); 1536 val = packet_get_string(&val_len); 1537 packet_check_eom(); 1538 1539 /* Don't set too many environment variables */ 1540 if (s->num_env > 128) { 1541 debug2("Ignoring env request %s: too many env vars", name); 1542 goto fail; 1543 } 1544 1545 for (i = 0; i < options.num_accept_env; i++) { 1546 if (match_pattern(name, options.accept_env[i])) { 1547 debug2("Setting env %d: %s=%s", s->num_env, name, val); 1548 s->env = xrealloc(s->env, sizeof(*s->env) * 1549 (s->num_env + 1)); 1550 s->env[s->num_env].name = name; 1551 s->env[s->num_env].val = val; 1552 s->num_env++; 1553 return (1); 1554 } 1555 } 1556 debug2("Ignoring env request %s: disallowed name", name); 1557 1558 fail: 1559 xfree(name); 1560 xfree(val); 1561 return (0); 1562 } 1563 1564 static int 1565 session_auth_agent_req(Session *s) 1566 { 1567 static int called = 0; 1568 packet_check_eom(); 1569 if (no_agent_forwarding_flag) { 1570 debug("session_auth_agent_req: no_agent_forwarding_flag"); 1571 return 0; 1572 } 1573 if (called) { 1574 return 0; 1575 } else { 1576 called = 1; 1577 return auth_input_request_forwarding(s->pw); 1578 } 1579 } 1580 1581 int 1582 session_input_channel_req(Channel *c, const char *rtype) 1583 { 1584 int success = 0; 1585 Session *s; 1586 1587 if ((s = session_by_channel(c->self)) == NULL) { 1588 logit("session_input_channel_req: no session %d req %.100s", 1589 c->self, rtype); 1590 return 0; 1591 } 1592 debug("session_input_channel_req: session %d req %s", s->self, rtype); 1593 1594 /* 1595 * a session is in LARVAL state until a shell, a command 1596 * or a subsystem is executed 1597 */ 1598 if (c->type == SSH_CHANNEL_LARVAL) { 1599 if (strcmp(rtype, "shell") == 0) { 1600 success = session_shell_req(s); 1601 } else if (strcmp(rtype, "exec") == 0) { 1602 success = session_exec_req(s); 1603 } else if (strcmp(rtype, "pty-req") == 0) { 1604 success = session_pty_req(s); 1605 } else if (strcmp(rtype, "x11-req") == 0) { 1606 success = session_x11_req(s); 1607 } else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) { 1608 success = session_auth_agent_req(s); 1609 } else if (strcmp(rtype, "subsystem") == 0) { 1610 success = session_subsystem_req(s); 1611 } else if (strcmp(rtype, "env") == 0) { 1612 success = session_env_req(s); 1613 } 1614 } 1615 if (strcmp(rtype, "window-change") == 0) { 1616 success = session_window_change_req(s); 1617 } else if (strcmp(rtype, "break") == 0) { 1618 success = session_break_req(s); 1619 } 1620 1621 return success; 1622 } 1623 1624 void 1625 session_set_fds(Session *s, int fdin, int fdout, int fderr) 1626 { 1627 if (!compat20) 1628 fatal("session_set_fds: called for proto != 2.0"); 1629 /* 1630 * now that have a child and a pipe to the child, 1631 * we can activate our channel and register the fd's 1632 */ 1633 if (s->chanid == -1) 1634 fatal("no channel for session %d", s->self); 1635 channel_set_fds(s->chanid, 1636 fdout, fdin, fderr, 1637 fderr == -1 ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ, 1638 1, 1639 CHAN_SES_WINDOW_DEFAULT); 1640 } 1641 1642 /* 1643 * Function to perform pty cleanup. Also called if we get aborted abnormally 1644 * (e.g., due to a dropped connection). 1645 */ 1646 void 1647 session_pty_cleanup2(Session *s) 1648 { 1649 if (s == NULL) { 1650 error("session_pty_cleanup: no session"); 1651 return; 1652 } 1653 if (s->ttyfd == -1) 1654 return; 1655 1656 debug("session_pty_cleanup: session %d release %s", s->self, s->tty); 1657 1658 /* Record that the user has logged out. */ 1659 if (s->pid != 0) 1660 record_logout(s->pid, s->tty); 1661 1662 /* Release the pseudo-tty. */ 1663 if (getuid() == 0) 1664 pty_release(s->tty); 1665 1666 /* 1667 * Close the server side of the socket pairs. We must do this after 1668 * the pty cleanup, so that another process doesn't get this pty 1669 * while we're still cleaning up. 1670 */ 1671 if (close(s->ptymaster) < 0) 1672 error("close(s->ptymaster/%d): %s", s->ptymaster, strerror(errno)); 1673 1674 /* unlink pty from session */ 1675 s->ttyfd = -1; 1676 } 1677 1678 void 1679 session_pty_cleanup(Session *s) 1680 { 1681 PRIVSEP(session_pty_cleanup2(s)); 1682 } 1683 1684 static char * 1685 sig2name(int sig) 1686 { 1687 #define SSH_SIG(x) if (sig == SIG ## x) return #x 1688 SSH_SIG(ABRT); 1689 SSH_SIG(ALRM); 1690 SSH_SIG(FPE); 1691 SSH_SIG(HUP); 1692 SSH_SIG(ILL); 1693 SSH_SIG(INT); 1694 SSH_SIG(KILL); 1695 SSH_SIG(PIPE); 1696 SSH_SIG(QUIT); 1697 SSH_SIG(SEGV); 1698 SSH_SIG(TERM); 1699 SSH_SIG(USR1); 1700 SSH_SIG(USR2); 1701 #undef SSH_SIG 1702 return "SIG@openssh.com"; 1703 } 1704 1705 static void 1706 session_exit_message(Session *s, int status) 1707 { 1708 Channel *c; 1709 1710 if ((c = channel_lookup(s->chanid)) == NULL) 1711 fatal("session_exit_message: session %d: no channel %d", 1712 s->self, s->chanid); 1713 debug("session_exit_message: session %d channel %d pid %ld", 1714 s->self, s->chanid, (long)s->pid); 1715 1716 if (WIFEXITED(status)) { 1717 channel_request_start(s->chanid, "exit-status", 0); 1718 packet_put_int(WEXITSTATUS(status)); 1719 packet_send(); 1720 } else if (WIFSIGNALED(status)) { 1721 channel_request_start(s->chanid, "exit-signal", 0); 1722 packet_put_cstring(sig2name(WTERMSIG(status))); 1723 packet_put_char(WCOREDUMP(status)); 1724 packet_put_cstring(""); 1725 packet_put_cstring(""); 1726 packet_send(); 1727 } else { 1728 /* Some weird exit cause. Just exit. */ 1729 packet_disconnect("wait returned status %04x.", status); 1730 } 1731 1732 /* disconnect channel */ 1733 debug("session_exit_message: release channel %d", s->chanid); 1734 channel_cancel_cleanup(s->chanid); 1735 /* 1736 * emulate a write failure with 'chan_write_failed', nobody will be 1737 * interested in data we write. 1738 * Note that we must not call 'chan_read_failed', since there could 1739 * be some more data waiting in the pipe. 1740 */ 1741 if (c->ostate != CHAN_OUTPUT_CLOSED) 1742 chan_write_failed(c); 1743 s->chanid = -1; 1744 } 1745 1746 void 1747 session_close(Session *s) 1748 { 1749 int i; 1750 1751 debug("session_close: session %d pid %ld", s->self, (long)s->pid); 1752 if (s->ttyfd != -1) 1753 session_pty_cleanup(s); 1754 if (s->term) 1755 xfree(s->term); 1756 if (s->display) 1757 xfree(s->display); 1758 if (s->auth_display) 1759 xfree(s->auth_display); 1760 if (s->auth_data) 1761 xfree(s->auth_data); 1762 if (s->auth_proto) 1763 xfree(s->auth_proto); 1764 s->used = 0; 1765 for (i = 0; i < s->num_env; i++) { 1766 xfree(s->env[i].name); 1767 xfree(s->env[i].val); 1768 } 1769 if (s->env != NULL) 1770 xfree(s->env); 1771 session_proctitle(s); 1772 } 1773 1774 void 1775 session_close_by_pid(pid_t pid, int status) 1776 { 1777 Session *s = session_by_pid(pid); 1778 if (s == NULL) { 1779 debug("session_close_by_pid: no session for pid %ld", 1780 (long)pid); 1781 return; 1782 } 1783 if (s->chanid != -1) 1784 session_exit_message(s, status); 1785 session_close(s); 1786 } 1787 1788 /* 1789 * this is called when a channel dies before 1790 * the session 'child' itself dies 1791 */ 1792 void 1793 session_close_by_channel(int id, void *arg) 1794 { 1795 Session *s = session_by_channel(id); 1796 if (s == NULL) { 1797 debug("session_close_by_channel: no session for id %d", id); 1798 return; 1799 } 1800 debug("session_close_by_channel: channel %d child %ld", 1801 id, (long)s->pid); 1802 if (s->pid != 0) { 1803 debug("session_close_by_channel: channel %d: has child", id); 1804 /* 1805 * delay detach of session, but release pty, since 1806 * the fd's to the child are already closed 1807 */ 1808 if (s->ttyfd != -1) 1809 session_pty_cleanup(s); 1810 return; 1811 } 1812 /* detach by removing callback */ 1813 channel_cancel_cleanup(s->chanid); 1814 s->chanid = -1; 1815 session_close(s); 1816 } 1817 1818 void 1819 session_destroy_all(void (*closefunc)(Session *)) 1820 { 1821 int i; 1822 for (i = 0; i < MAX_SESSIONS; i++) { 1823 Session *s = &sessions[i]; 1824 if (s->used) { 1825 if (closefunc != NULL) 1826 closefunc(s); 1827 else 1828 session_close(s); 1829 } 1830 } 1831 } 1832 1833 static char * 1834 session_tty_list(void) 1835 { 1836 static char buf[1024]; 1837 int i; 1838 buf[0] = '\0'; 1839 for (i = 0; i < MAX_SESSIONS; i++) { 1840 Session *s = &sessions[i]; 1841 if (s->used && s->ttyfd != -1) { 1842 if (buf[0] != '\0') 1843 strlcat(buf, ",", sizeof buf); 1844 strlcat(buf, strrchr(s->tty, '/') + 1, sizeof buf); 1845 } 1846 } 1847 if (buf[0] == '\0') 1848 strlcpy(buf, "notty", sizeof buf); 1849 return buf; 1850 } 1851 1852 void 1853 session_proctitle(Session *s) 1854 { 1855 if (s->pw == NULL) 1856 error("no user for session %d", s->self); 1857 else 1858 setproctitle("%s@%s", s->pw->pw_name, session_tty_list()); 1859 } 1860 1861 int 1862 session_setup_x11fwd(Session *s) 1863 { 1864 struct stat st; 1865 char display[512], auth_display[512]; 1866 char hostname[MAXHOSTNAMELEN]; 1867 1868 if (no_x11_forwarding_flag) { 1869 packet_send_debug("X11 forwarding disabled in user configuration file."); 1870 return 0; 1871 } 1872 if (!options.x11_forwarding) { 1873 debug("X11 forwarding disabled in server configuration file."); 1874 return 0; 1875 } 1876 if (!options.xauth_location || 1877 (stat(options.xauth_location, &st) == -1)) { 1878 packet_send_debug("No xauth program; cannot forward with spoofing."); 1879 return 0; 1880 } 1881 if (options.use_login) { 1882 packet_send_debug("X11 forwarding disabled; " 1883 "not compatible with UseLogin=yes."); 1884 return 0; 1885 } 1886 if (s->display != NULL) { 1887 debug("X11 display already set."); 1888 return 0; 1889 } 1890 if (x11_create_display_inet(options.x11_display_offset, 1891 options.x11_use_localhost, s->single_connection, 1892 &s->display_number) == -1) { 1893 debug("x11_create_display_inet failed."); 1894 return 0; 1895 } 1896 1897 /* Set up a suitable value for the DISPLAY variable. */ 1898 if (gethostname(hostname, sizeof(hostname)) < 0) 1899 fatal("gethostname: %.100s", strerror(errno)); 1900 /* 1901 * auth_display must be used as the displayname when the 1902 * authorization entry is added with xauth(1). This will be 1903 * different than the DISPLAY string for localhost displays. 1904 */ 1905 if (options.x11_use_localhost) { 1906 snprintf(display, sizeof display, "localhost:%u.%u", 1907 s->display_number, s->screen); 1908 snprintf(auth_display, sizeof auth_display, "unix:%u.%u", 1909 s->display_number, s->screen); 1910 s->display = xstrdup(display); 1911 s->auth_display = xstrdup(auth_display); 1912 } else { 1913 snprintf(display, sizeof display, "%.400s:%u.%u", hostname, 1914 s->display_number, s->screen); 1915 s->display = xstrdup(display); 1916 s->auth_display = xstrdup(display); 1917 } 1918 1919 return 1; 1920 } 1921 1922 static void 1923 do_authenticated2(Authctxt *authctxt) 1924 { 1925 server_loop2(authctxt); 1926 } 1927 1928 void 1929 do_cleanup(Authctxt *authctxt) 1930 { 1931 static int called = 0; 1932 1933 debug("do_cleanup"); 1934 1935 /* no cleanup if we're in the child for login shell */ 1936 if (is_child) 1937 return; 1938 1939 /* avoid double cleanup */ 1940 if (called) 1941 return; 1942 called = 1; 1943 1944 if (authctxt == NULL) 1945 return; 1946 #ifdef KRB5 1947 if (options.kerberos_ticket_cleanup && 1948 authctxt->krb5_ctx) 1949 krb5_cleanup_proc(authctxt); 1950 #endif 1951 1952 #ifdef GSSAPI 1953 if (compat20 && options.gss_cleanup_creds) 1954 ssh_gssapi_cleanup_creds(); 1955 #endif 1956 1957 /* remove agent socket */ 1958 auth_sock_cleanup_proc(authctxt->pw); 1959 1960 /* 1961 * Cleanup ptys/utmp only if privsep is disabled, 1962 * or if running in monitor. 1963 */ 1964 if (!use_privsep || mm_is_monitor()) 1965 session_destroy_all(session_pty_cleanup2); 1966 } 1967