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 1.180 2004/07/28 09:40:29 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 s->authctxt = authctxt; 246 s->pw = authctxt->pw; 247 248 /* 249 * We stay in this loop until the client requests to execute a shell 250 * or a command. 251 */ 252 for (;;) { 253 success = 0; 254 255 /* Get a packet from the client. */ 256 type = packet_read(); 257 258 /* Process the packet. */ 259 switch (type) { 260 case SSH_CMSG_REQUEST_COMPRESSION: 261 compression_level = packet_get_int(); 262 packet_check_eom(); 263 if (compression_level < 1 || compression_level > 9) { 264 packet_send_debug("Received invalid compression level %d.", 265 compression_level); 266 break; 267 } 268 if (!options.compression) { 269 debug2("compression disabled"); 270 break; 271 } 272 /* Enable compression after we have responded with SUCCESS. */ 273 enable_compression_after_reply = 1; 274 success = 1; 275 break; 276 277 case SSH_CMSG_REQUEST_PTY: 278 success = session_pty_req(s); 279 break; 280 281 case SSH_CMSG_X11_REQUEST_FORWARDING: 282 s->auth_proto = packet_get_string(&proto_len); 283 s->auth_data = packet_get_string(&data_len); 284 285 screen_flag = packet_get_protocol_flags() & 286 SSH_PROTOFLAG_SCREEN_NUMBER; 287 debug2("SSH_PROTOFLAG_SCREEN_NUMBER: %d", screen_flag); 288 289 if (packet_remaining() == 4) { 290 if (!screen_flag) 291 debug2("Buggy client: " 292 "X11 screen flag missing"); 293 s->screen = packet_get_int(); 294 } else { 295 s->screen = 0; 296 } 297 packet_check_eom(); 298 success = session_setup_x11fwd(s); 299 if (!success) { 300 xfree(s->auth_proto); 301 xfree(s->auth_data); 302 s->auth_proto = NULL; 303 s->auth_data = NULL; 304 } 305 break; 306 307 case SSH_CMSG_AGENT_REQUEST_FORWARDING: 308 if (no_agent_forwarding_flag || compat13) { 309 debug("Authentication agent forwarding not permitted for this authentication."); 310 break; 311 } 312 debug("Received authentication agent forwarding request."); 313 success = auth_input_request_forwarding(s->pw); 314 break; 315 316 case SSH_CMSG_PORT_FORWARD_REQUEST: 317 if (no_port_forwarding_flag) { 318 debug("Port forwarding not permitted for this authentication."); 319 break; 320 } 321 if (!options.allow_tcp_forwarding) { 322 debug("Port forwarding not permitted."); 323 break; 324 } 325 debug("Received TCP/IP port forwarding request."); 326 channel_input_port_forward_request(s->pw->pw_uid == 0, options.gateway_ports); 327 success = 1; 328 break; 329 330 case SSH_CMSG_MAX_PACKET_SIZE: 331 if (packet_set_maxsize(packet_get_int()) > 0) 332 success = 1; 333 break; 334 335 case SSH_CMSG_EXEC_SHELL: 336 case SSH_CMSG_EXEC_CMD: 337 if (type == SSH_CMSG_EXEC_CMD) { 338 command = packet_get_string(&dlen); 339 debug("Exec command '%.500s'", command); 340 do_exec(s, command); 341 xfree(command); 342 } else { 343 do_exec(s, NULL); 344 } 345 packet_check_eom(); 346 session_close(s); 347 return; 348 349 default: 350 /* 351 * Any unknown messages in this phase are ignored, 352 * and a failure message is returned. 353 */ 354 logit("Unknown packet type received after authentication: %d", type); 355 } 356 packet_start(success ? SSH_SMSG_SUCCESS : SSH_SMSG_FAILURE); 357 packet_send(); 358 packet_write_wait(); 359 360 /* Enable compression now that we have replied if appropriate. */ 361 if (enable_compression_after_reply) { 362 enable_compression_after_reply = 0; 363 packet_start_compression(compression_level); 364 } 365 } 366 } 367 368 /* 369 * This is called to fork and execute a command when we have no tty. This 370 * will call do_child from the child, and server_loop from the parent after 371 * setting up file descriptors and such. 372 */ 373 void 374 do_exec_no_pty(Session *s, const char *command) 375 { 376 pid_t pid; 377 378 #ifdef USE_PIPES 379 int pin[2], pout[2], perr[2]; 380 /* Allocate pipes for communicating with the program. */ 381 if (pipe(pin) < 0 || pipe(pout) < 0 || pipe(perr) < 0) 382 packet_disconnect("Could not create pipes: %.100s", 383 strerror(errno)); 384 #else /* USE_PIPES */ 385 int inout[2], err[2]; 386 /* Uses socket pairs to communicate with the program. */ 387 if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) < 0 || 388 socketpair(AF_UNIX, SOCK_STREAM, 0, err) < 0) 389 packet_disconnect("Could not create socket pairs: %.100s", 390 strerror(errno)); 391 #endif /* USE_PIPES */ 392 if (s == NULL) 393 fatal("do_exec_no_pty: no session"); 394 395 session_proctitle(s); 396 397 /* Fork the child. */ 398 if ((pid = fork()) == 0) { 399 is_child = 1; 400 401 /* Child. Reinitialize the log since the pid has changed. */ 402 log_init(__progname, options.log_level, options.log_facility, log_stderr); 403 404 /* 405 * Create a new session and process group since the 4.4BSD 406 * setlogin() affects the entire process group. 407 */ 408 if (setsid() < 0) 409 error("setsid failed: %.100s", strerror(errno)); 410 411 #ifdef USE_PIPES 412 /* 413 * Redirect stdin. We close the parent side of the socket 414 * pair, and make the child side the standard input. 415 */ 416 close(pin[1]); 417 if (dup2(pin[0], 0) < 0) 418 perror("dup2 stdin"); 419 close(pin[0]); 420 421 /* Redirect stdout. */ 422 close(pout[0]); 423 if (dup2(pout[1], 1) < 0) 424 perror("dup2 stdout"); 425 close(pout[1]); 426 427 /* Redirect stderr. */ 428 close(perr[0]); 429 if (dup2(perr[1], 2) < 0) 430 perror("dup2 stderr"); 431 close(perr[1]); 432 #else /* USE_PIPES */ 433 /* 434 * Redirect stdin, stdout, and stderr. Stdin and stdout will 435 * use the same socket, as some programs (particularly rdist) 436 * seem to depend on it. 437 */ 438 close(inout[1]); 439 close(err[1]); 440 if (dup2(inout[0], 0) < 0) /* stdin */ 441 perror("dup2 stdin"); 442 if (dup2(inout[0], 1) < 0) /* stdout. Note: same socket as stdin. */ 443 perror("dup2 stdout"); 444 if (dup2(err[0], 2) < 0) /* stderr */ 445 perror("dup2 stderr"); 446 #endif /* USE_PIPES */ 447 448 /* Do processing for the child (exec command etc). */ 449 do_child(s, command); 450 /* NOTREACHED */ 451 } 452 if (pid < 0) 453 packet_disconnect("fork failed: %.100s", strerror(errno)); 454 s->pid = pid; 455 /* Set interactive/non-interactive mode. */ 456 packet_set_interactive(s->display != NULL); 457 #ifdef USE_PIPES 458 /* We are the parent. Close the child sides of the pipes. */ 459 close(pin[0]); 460 close(pout[1]); 461 close(perr[1]); 462 463 if (compat20) { 464 if (s->is_subsystem) { 465 close(perr[0]); 466 perr[0] = -1; 467 } 468 session_set_fds(s, pin[1], pout[0], perr[0]); 469 } else { 470 /* Enter the interactive session. */ 471 server_loop(pid, pin[1], pout[0], perr[0]); 472 /* server_loop has closed pin[1], pout[0], and perr[0]. */ 473 } 474 #else /* USE_PIPES */ 475 /* We are the parent. Close the child sides of the socket pairs. */ 476 close(inout[0]); 477 close(err[0]); 478 479 /* 480 * Enter the interactive session. Note: server_loop must be able to 481 * handle the case that fdin and fdout are the same. 482 */ 483 if (compat20) { 484 session_set_fds(s, inout[1], inout[1], s->is_subsystem ? -1 : err[1]); 485 } else { 486 server_loop(pid, inout[1], inout[1], err[1]); 487 /* server_loop has closed inout[1] and err[1]. */ 488 } 489 #endif /* USE_PIPES */ 490 } 491 492 /* 493 * This is called to fork and execute a command when we have a tty. This 494 * will call do_child from the child, and server_loop from the parent after 495 * setting up file descriptors, controlling tty, updating wtmp, utmp, 496 * lastlog, and other such operations. 497 */ 498 void 499 do_exec_pty(Session *s, const char *command) 500 { 501 int fdout, ptyfd, ttyfd, ptymaster; 502 pid_t pid; 503 504 if (s == NULL) 505 fatal("do_exec_pty: no session"); 506 ptyfd = s->ptyfd; 507 ttyfd = s->ttyfd; 508 509 /* Fork the child. */ 510 if ((pid = fork()) == 0) { 511 is_child = 1; 512 513 /* Child. Reinitialize the log because the pid has changed. */ 514 log_init(__progname, options.log_level, options.log_facility, log_stderr); 515 /* Close the master side of the pseudo tty. */ 516 close(ptyfd); 517 518 /* Make the pseudo tty our controlling tty. */ 519 pty_make_controlling_tty(&ttyfd, s->tty); 520 521 /* Redirect stdin/stdout/stderr from the pseudo tty. */ 522 if (dup2(ttyfd, 0) < 0) 523 error("dup2 stdin: %s", strerror(errno)); 524 if (dup2(ttyfd, 1) < 0) 525 error("dup2 stdout: %s", strerror(errno)); 526 if (dup2(ttyfd, 2) < 0) 527 error("dup2 stderr: %s", strerror(errno)); 528 529 /* Close the extra descriptor for the pseudo tty. */ 530 close(ttyfd); 531 532 /* record login, etc. similar to login(1) */ 533 if (!(options.use_login && command == NULL)) 534 do_login(s, command); 535 536 /* Do common processing for the child, such as execing the command. */ 537 do_child(s, command); 538 /* NOTREACHED */ 539 } 540 if (pid < 0) 541 packet_disconnect("fork failed: %.100s", strerror(errno)); 542 s->pid = pid; 543 544 /* Parent. Close the slave side of the pseudo tty. */ 545 close(ttyfd); 546 547 /* 548 * Create another descriptor of the pty master side for use as the 549 * standard input. We could use the original descriptor, but this 550 * simplifies code in server_loop. The descriptor is bidirectional. 551 */ 552 fdout = dup(ptyfd); 553 if (fdout < 0) 554 packet_disconnect("dup #1 failed: %.100s", strerror(errno)); 555 556 /* we keep a reference to the pty master */ 557 ptymaster = dup(ptyfd); 558 if (ptymaster < 0) 559 packet_disconnect("dup #2 failed: %.100s", strerror(errno)); 560 s->ptymaster = ptymaster; 561 562 /* Enter interactive session. */ 563 packet_set_interactive(1); 564 if (compat20) { 565 session_set_fds(s, ptyfd, fdout, -1); 566 } else { 567 server_loop(pid, ptyfd, fdout, -1); 568 /* server_loop _has_ closed ptyfd and fdout. */ 569 } 570 } 571 572 /* 573 * This is called to fork and execute a command. If another command is 574 * to be forced, execute that instead. 575 */ 576 void 577 do_exec(Session *s, const char *command) 578 { 579 if (forced_command) { 580 original_command = command; 581 command = forced_command; 582 debug("Forced command '%.900s'", command); 583 } 584 585 #ifdef GSSAPI 586 if (options.gss_authentication) { 587 temporarily_use_uid(s->pw); 588 ssh_gssapi_storecreds(); 589 restore_uid(); 590 } 591 #endif 592 593 if (s->ttyfd != -1) 594 do_exec_pty(s, command); 595 else 596 do_exec_no_pty(s, command); 597 598 original_command = NULL; 599 600 /* 601 * Clear loginmsg: it's the child's responsibility to display 602 * it to the user, otherwise multiple sessions may accumulate 603 * multiple copies of the login messages. 604 */ 605 buffer_clear(&loginmsg); 606 } 607 608 609 /* administrative, login(1)-like work */ 610 void 611 do_login(Session *s, const char *command) 612 { 613 socklen_t fromlen; 614 struct sockaddr_storage from; 615 struct passwd * pw = s->pw; 616 pid_t pid = getpid(); 617 618 /* 619 * Get IP address of client. If the connection is not a socket, let 620 * the address be 0.0.0.0. 621 */ 622 memset(&from, 0, sizeof(from)); 623 fromlen = sizeof(from); 624 if (packet_connection_is_on_socket()) { 625 if (getpeername(packet_get_connection_in(), 626 (struct sockaddr *) & from, &fromlen) < 0) { 627 debug("getpeername: %.100s", strerror(errno)); 628 cleanup_exit(255); 629 } 630 } 631 632 /* Record that there was a login on that tty from the remote host. */ 633 if (!use_privsep) 634 record_login(pid, s->tty, pw->pw_name, pw->pw_uid, 635 get_remote_name_or_ip(utmp_len, 636 options.use_dns), 637 (struct sockaddr *)&from, fromlen); 638 639 if (check_quietlogin(s, command)) 640 return; 641 642 display_loginmsg(); 643 644 do_motd(); 645 } 646 647 /* 648 * Display the message of the day. 649 */ 650 void 651 do_motd(void) 652 { 653 FILE *f; 654 char buf[256]; 655 656 if (options.print_motd) { 657 #ifdef HAVE_LOGIN_CAP 658 f = fopen(login_getcapstr(lc, "welcome", "/etc/motd", 659 "/etc/motd"), "r"); 660 #else 661 f = fopen("/etc/motd", "r"); 662 #endif 663 if (f) { 664 while (fgets(buf, sizeof(buf), f)) 665 fputs(buf, stdout); 666 fclose(f); 667 } 668 } 669 } 670 671 672 /* 673 * Check for quiet login, either .hushlogin or command given. 674 */ 675 int 676 check_quietlogin(Session *s, const char *command) 677 { 678 char buf[256]; 679 struct passwd *pw = s->pw; 680 struct stat st; 681 682 /* Return 1 if .hushlogin exists or a command given. */ 683 if (command != NULL) 684 return 1; 685 snprintf(buf, sizeof(buf), "%.200s/.hushlogin", pw->pw_dir); 686 #ifdef HAVE_LOGIN_CAP 687 if (login_getcapbool(lc, "hushlogin", 0) || stat(buf, &st) >= 0) 688 return 1; 689 #else 690 if (stat(buf, &st) >= 0) 691 return 1; 692 #endif 693 return 0; 694 } 695 696 /* 697 * Sets the value of the given variable in the environment. If the variable 698 * already exists, its value is overriden. 699 */ 700 void 701 child_set_env(char ***envp, u_int *envsizep, const char *name, 702 const char *value) 703 { 704 char **env; 705 u_int envsize; 706 u_int i, namelen; 707 708 /* 709 * Find the slot where the value should be stored. If the variable 710 * already exists, we reuse the slot; otherwise we append a new slot 711 * at the end of the array, expanding if necessary. 712 */ 713 env = *envp; 714 namelen = strlen(name); 715 for (i = 0; env[i]; i++) 716 if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=') 717 break; 718 if (env[i]) { 719 /* Reuse the slot. */ 720 xfree(env[i]); 721 } else { 722 /* New variable. Expand if necessary. */ 723 envsize = *envsizep; 724 if (i >= envsize - 1) { 725 if (envsize >= 1000) 726 fatal("child_set_env: too many env vars"); 727 envsize += 50; 728 env = (*envp) = xrealloc(env, envsize * sizeof(char *)); 729 *envsizep = envsize; 730 } 731 /* Need to set the NULL pointer at end of array beyond the new slot. */ 732 env[i + 1] = NULL; 733 } 734 735 /* Allocate space and format the variable in the appropriate slot. */ 736 env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1); 737 snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value); 738 } 739 740 /* 741 * Reads environment variables from the given file and adds/overrides them 742 * into the environment. If the file does not exist, this does nothing. 743 * Otherwise, it must consist of empty lines, comments (line starts with '#') 744 * and assignments of the form name=value. No other forms are allowed. 745 */ 746 static void 747 read_environment_file(char ***env, u_int *envsize, 748 const char *filename) 749 { 750 FILE *f; 751 char buf[4096]; 752 char *cp, *value; 753 u_int lineno = 0; 754 755 f = fopen(filename, "r"); 756 if (!f) 757 return; 758 759 while (fgets(buf, sizeof(buf), f)) { 760 if (++lineno > 1000) 761 fatal("Too many lines in environment file %s", filename); 762 for (cp = buf; *cp == ' ' || *cp == '\t'; cp++) 763 ; 764 if (!*cp || *cp == '#' || *cp == '\n') 765 continue; 766 if (strchr(cp, '\n')) 767 *strchr(cp, '\n') = '\0'; 768 value = strchr(cp, '='); 769 if (value == NULL) { 770 fprintf(stderr, "Bad line %u in %.100s\n", lineno, 771 filename); 772 continue; 773 } 774 /* 775 * Replace the equals sign by nul, and advance value to 776 * the value string. 777 */ 778 *value = '\0'; 779 value++; 780 child_set_env(env, envsize, cp, value); 781 } 782 fclose(f); 783 } 784 785 static char ** 786 do_setup_env(Session *s, const char *shell) 787 { 788 char buf[256]; 789 u_int i, envsize; 790 char **env, *laddr; 791 struct passwd *pw = s->pw; 792 793 /* Initialize the environment. */ 794 envsize = 100; 795 env = xmalloc(envsize * sizeof(char *)); 796 env[0] = NULL; 797 798 #ifdef GSSAPI 799 /* Allow any GSSAPI methods that we've used to alter 800 * the childs environment as they see fit 801 */ 802 ssh_gssapi_do_child(&env, &envsize); 803 #endif 804 805 if (!options.use_login) { 806 /* Set basic environment. */ 807 for (i = 0; i < s->num_env; i++) 808 child_set_env(&env, &envsize, s->env[i].name, 809 s->env[i].val); 810 811 child_set_env(&env, &envsize, "USER", pw->pw_name); 812 child_set_env(&env, &envsize, "LOGNAME", pw->pw_name); 813 child_set_env(&env, &envsize, "HOME", pw->pw_dir); 814 #ifdef HAVE_LOGIN_CAP 815 if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETPATH) < 0) 816 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); 817 else 818 child_set_env(&env, &envsize, "PATH", getenv("PATH")); 819 #else 820 child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); 821 #endif 822 823 snprintf(buf, sizeof buf, "%.200s/%.50s", 824 _PATH_MAILDIR, pw->pw_name); 825 child_set_env(&env, &envsize, "MAIL", buf); 826 827 /* Normal systems set SHELL by default. */ 828 child_set_env(&env, &envsize, "SHELL", shell); 829 } 830 if (getenv("TZ")) 831 child_set_env(&env, &envsize, "TZ", getenv("TZ")); 832 833 /* Set custom environment options from RSA authentication. */ 834 if (!options.use_login) { 835 while (custom_environment) { 836 struct envstring *ce = custom_environment; 837 char *str = ce->s; 838 839 for (i = 0; str[i] != '=' && str[i]; i++) 840 ; 841 if (str[i] == '=') { 842 str[i] = 0; 843 child_set_env(&env, &envsize, str, str + i + 1); 844 } 845 custom_environment = ce->next; 846 xfree(ce->s); 847 xfree(ce); 848 } 849 } 850 851 /* SSH_CLIENT deprecated */ 852 snprintf(buf, sizeof buf, "%.50s %d %d", 853 get_remote_ipaddr(), get_remote_port(), get_local_port()); 854 child_set_env(&env, &envsize, "SSH_CLIENT", buf); 855 856 laddr = get_local_ipaddr(packet_get_connection_in()); 857 snprintf(buf, sizeof buf, "%.50s %d %.50s %d", 858 get_remote_ipaddr(), get_remote_port(), laddr, get_local_port()); 859 xfree(laddr); 860 child_set_env(&env, &envsize, "SSH_CONNECTION", buf); 861 862 if (s->ttyfd != -1) 863 child_set_env(&env, &envsize, "SSH_TTY", s->tty); 864 if (s->term) 865 child_set_env(&env, &envsize, "TERM", s->term); 866 if (s->display) 867 child_set_env(&env, &envsize, "DISPLAY", s->display); 868 if (original_command) 869 child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND", 870 original_command); 871 #ifdef KRB5 872 if (s->authctxt->krb5_ticket_file) 873 child_set_env(&env, &envsize, "KRB5CCNAME", 874 s->authctxt->krb5_ticket_file); 875 #endif 876 if (auth_sock_name != NULL) 877 child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME, 878 auth_sock_name); 879 880 /* read $HOME/.ssh/environment. */ 881 if (options.permit_user_env && !options.use_login) { 882 snprintf(buf, sizeof buf, "%.200s/.ssh/environment", 883 pw->pw_dir); 884 read_environment_file(&env, &envsize, buf); 885 } 886 if (debug_flag) { 887 /* dump the environment */ 888 fprintf(stderr, "Environment:\n"); 889 for (i = 0; env[i]; i++) 890 fprintf(stderr, " %.200s\n", env[i]); 891 } 892 return env; 893 } 894 895 /* 896 * Run $HOME/.ssh/rc, /etc/ssh/sshrc, or xauth (whichever is found 897 * first in this order). 898 */ 899 static void 900 do_rc_files(Session *s, const char *shell) 901 { 902 FILE *f = NULL; 903 char cmd[1024]; 904 int do_xauth; 905 struct stat st; 906 907 do_xauth = 908 s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL; 909 910 /* ignore _PATH_SSH_USER_RC for subsystems */ 911 if (!s->is_subsystem && (stat(_PATH_SSH_USER_RC, &st) >= 0)) { 912 snprintf(cmd, sizeof cmd, "%s -c '%s %s'", 913 shell, _PATH_BSHELL, _PATH_SSH_USER_RC); 914 if (debug_flag) 915 fprintf(stderr, "Running %s\n", cmd); 916 f = popen(cmd, "w"); 917 if (f) { 918 if (do_xauth) 919 fprintf(f, "%s %s\n", s->auth_proto, 920 s->auth_data); 921 pclose(f); 922 } else 923 fprintf(stderr, "Could not run %s\n", 924 _PATH_SSH_USER_RC); 925 } else if (stat(_PATH_SSH_SYSTEM_RC, &st) >= 0) { 926 if (debug_flag) 927 fprintf(stderr, "Running %s %s\n", _PATH_BSHELL, 928 _PATH_SSH_SYSTEM_RC); 929 f = popen(_PATH_BSHELL " " _PATH_SSH_SYSTEM_RC, "w"); 930 if (f) { 931 if (do_xauth) 932 fprintf(f, "%s %s\n", s->auth_proto, 933 s->auth_data); 934 pclose(f); 935 } else 936 fprintf(stderr, "Could not run %s\n", 937 _PATH_SSH_SYSTEM_RC); 938 } else if (do_xauth && options.xauth_location != NULL) { 939 /* Add authority data to .Xauthority if appropriate. */ 940 if (debug_flag) { 941 fprintf(stderr, 942 "Running %.500s remove %.100s\n", 943 options.xauth_location, s->auth_display); 944 fprintf(stderr, 945 "%.500s add %.100s %.100s %.100s\n", 946 options.xauth_location, s->auth_display, 947 s->auth_proto, s->auth_data); 948 } 949 snprintf(cmd, sizeof cmd, "%s -q -", 950 options.xauth_location); 951 f = popen(cmd, "w"); 952 if (f) { 953 fprintf(f, "remove %s\n", 954 s->auth_display); 955 fprintf(f, "add %s %s %s\n", 956 s->auth_display, s->auth_proto, 957 s->auth_data); 958 pclose(f); 959 } else { 960 fprintf(stderr, "Could not run %s\n", 961 cmd); 962 } 963 } 964 } 965 966 static void 967 do_nologin(struct passwd *pw) 968 { 969 FILE *f = NULL; 970 char buf[1024]; 971 972 #ifdef HAVE_LOGIN_CAP 973 if (!login_getcapbool(lc, "ignorenologin", 0) && pw->pw_uid) 974 f = fopen(login_getcapstr(lc, "nologin", _PATH_NOLOGIN, 975 _PATH_NOLOGIN), "r"); 976 #else 977 if (pw->pw_uid) 978 f = fopen(_PATH_NOLOGIN, "r"); 979 #endif 980 if (f) { 981 /* /etc/nologin exists. Print its contents and exit. */ 982 logit("User %.100s not allowed because %s exists", 983 pw->pw_name, _PATH_NOLOGIN); 984 while (fgets(buf, sizeof(buf), f)) 985 fputs(buf, stderr); 986 fclose(f); 987 exit(254); 988 } 989 } 990 991 /* Set login name, uid, gid, and groups. */ 992 void 993 do_setusercontext(struct passwd *pw) 994 { 995 if (getuid() == 0 || geteuid() == 0) { 996 #ifdef HAVE_LOGIN_CAP 997 if (setusercontext(lc, pw, pw->pw_uid, 998 (LOGIN_SETALL & ~LOGIN_SETPATH)) < 0) { 999 perror("unable to set user context"); 1000 exit(1); 1001 } 1002 #else 1003 if (setlogin(pw->pw_name) < 0) 1004 error("setlogin failed: %s", strerror(errno)); 1005 if (setgid(pw->pw_gid) < 0) { 1006 perror("setgid"); 1007 exit(1); 1008 } 1009 /* Initialize the group list. */ 1010 if (initgroups(pw->pw_name, pw->pw_gid) < 0) { 1011 perror("initgroups"); 1012 exit(1); 1013 } 1014 endgrent(); 1015 1016 /* Permanently switch to the desired uid. */ 1017 permanently_set_uid(pw); 1018 #endif 1019 } 1020 if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) 1021 fatal("Failed to set uids to %u.", (u_int) pw->pw_uid); 1022 } 1023 1024 static void 1025 do_pwchange(Session *s) 1026 { 1027 fflush(NULL); 1028 fprintf(stderr, "WARNING: Your password has expired.\n"); 1029 if (s->ttyfd != -1) { 1030 fprintf(stderr, 1031 "You must change your password now and login again!\n"); 1032 execl(_PATH_PASSWD_PROG, "passwd", (char *)NULL); 1033 perror("passwd"); 1034 } else { 1035 fprintf(stderr, 1036 "Password change required but no TTY available.\n"); 1037 } 1038 exit(1); 1039 } 1040 1041 static void 1042 launch_login(struct passwd *pw, const char *hostname) 1043 { 1044 /* Launch login(1). */ 1045 1046 execl("/usr/bin/login", "login", "-h", hostname, 1047 "-p", "-f", "--", pw->pw_name, (char *)NULL); 1048 1049 /* Login couldn't be executed, die. */ 1050 1051 perror("login"); 1052 exit(1); 1053 } 1054 1055 static void 1056 child_close_fds(void) 1057 { 1058 int i; 1059 1060 if (packet_get_connection_in() == packet_get_connection_out()) 1061 close(packet_get_connection_in()); 1062 else { 1063 close(packet_get_connection_in()); 1064 close(packet_get_connection_out()); 1065 } 1066 /* 1067 * Close all descriptors related to channels. They will still remain 1068 * open in the parent. 1069 */ 1070 /* XXX better use close-on-exec? -markus */ 1071 channel_close_all(); 1072 1073 /* 1074 * Close any extra file descriptors. Note that there may still be 1075 * descriptors left by system functions. They will be closed later. 1076 */ 1077 endpwent(); 1078 1079 /* 1080 * Close any extra open file descriptors so that we don\'t have them 1081 * hanging around in clients. Note that we want to do this after 1082 * initgroups, because at least on Solaris 2.3 it leaves file 1083 * descriptors open. 1084 */ 1085 for (i = 3; i < 64; i++) 1086 close(i); 1087 } 1088 1089 /* 1090 * Performs common processing for the child, such as setting up the 1091 * environment, closing extra file descriptors, setting the user and group 1092 * ids, and executing the command or shell. 1093 */ 1094 void 1095 do_child(Session *s, const char *command) 1096 { 1097 extern char **environ; 1098 char **env; 1099 char *argv[10]; 1100 const char *shell, *shell0, *hostname = NULL; 1101 struct passwd *pw = s->pw; 1102 1103 /* remove hostkey from the child's memory */ 1104 destroy_sensitive_data(); 1105 1106 /* Force a password change */ 1107 if (s->authctxt->force_pwchange) { 1108 do_setusercontext(pw); 1109 child_close_fds(); 1110 do_pwchange(s); 1111 exit(1); 1112 } 1113 1114 /* login(1) is only called if we execute the login shell */ 1115 if (options.use_login && command != NULL) 1116 options.use_login = 0; 1117 1118 /* 1119 * Login(1) does this as well, and it needs uid 0 for the "-h" 1120 * switch, so we let login(1) to this for us. 1121 */ 1122 if (!options.use_login) { 1123 do_nologin(pw); 1124 do_setusercontext(pw); 1125 } 1126 1127 /* 1128 * Get the shell from the password data. An empty shell field is 1129 * legal, and means /bin/sh. 1130 */ 1131 shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; 1132 1133 /* 1134 * Make sure $SHELL points to the shell from the password file, 1135 * even if shell is overridden from login.conf 1136 */ 1137 env = do_setup_env(s, shell); 1138 1139 #ifdef HAVE_LOGIN_CAP 1140 shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell); 1141 #endif 1142 1143 /* we have to stash the hostname before we close our socket. */ 1144 if (options.use_login) 1145 hostname = get_remote_name_or_ip(utmp_len, 1146 options.use_dns); 1147 /* 1148 * Close the connection descriptors; note that this is the child, and 1149 * the server will still have the socket open, and it is important 1150 * that we do not shutdown it. Note that the descriptors cannot be 1151 * closed before building the environment, as we call 1152 * get_remote_ipaddr there. 1153 */ 1154 child_close_fds(); 1155 1156 /* 1157 * Must take new environment into use so that .ssh/rc, 1158 * /etc/ssh/sshrc and xauth are run in the proper environment. 1159 */ 1160 environ = env; 1161 1162 #ifdef KRB5 1163 /* 1164 * At this point, we check to see if AFS is active and if we have 1165 * a valid Kerberos 5 TGT. If so, it seems like a good idea to see 1166 * if we can (and need to) extend the ticket into an AFS token. If 1167 * we don't do this, we run into potential problems if the user's 1168 * home directory is in AFS and it's not world-readable. 1169 */ 1170 1171 if (options.kerberos_get_afs_token && k_hasafs() && 1172 (s->authctxt->krb5_ctx != NULL)) { 1173 char cell[64]; 1174 1175 debug("Getting AFS token"); 1176 1177 k_setpag(); 1178 1179 if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0) 1180 krb5_afslog(s->authctxt->krb5_ctx, 1181 s->authctxt->krb5_fwd_ccache, cell, NULL); 1182 1183 krb5_afslog_home(s->authctxt->krb5_ctx, 1184 s->authctxt->krb5_fwd_ccache, NULL, NULL, pw->pw_dir); 1185 } 1186 #endif 1187 1188 /* Change current directory to the user\'s home directory. */ 1189 if (chdir(pw->pw_dir) < 0) { 1190 fprintf(stderr, "Could not chdir to home directory %s: %s\n", 1191 pw->pw_dir, strerror(errno)); 1192 #ifdef HAVE_LOGIN_CAP 1193 if (login_getcapbool(lc, "requirehome", 0)) 1194 exit(1); 1195 #endif 1196 } 1197 1198 if (!options.use_login) 1199 do_rc_files(s, shell); 1200 1201 /* restore SIGPIPE for child */ 1202 signal(SIGPIPE, SIG_DFL); 1203 1204 if (options.use_login) { 1205 launch_login(pw, hostname); 1206 /* NEVERREACHED */ 1207 } 1208 1209 /* Get the last component of the shell name. */ 1210 if ((shell0 = strrchr(shell, '/')) != NULL) 1211 shell0++; 1212 else 1213 shell0 = shell; 1214 1215 /* 1216 * If we have no command, execute the shell. In this case, the shell 1217 * name to be passed in argv[0] is preceded by '-' to indicate that 1218 * this is a login shell. 1219 */ 1220 if (!command) { 1221 char argv0[256]; 1222 1223 /* Start the shell. Set initial character to '-'. */ 1224 argv0[0] = '-'; 1225 1226 if (strlcpy(argv0 + 1, shell0, sizeof(argv0) - 1) 1227 >= sizeof(argv0) - 1) { 1228 errno = EINVAL; 1229 perror(shell); 1230 exit(1); 1231 } 1232 1233 /* Execute the shell. */ 1234 argv[0] = argv0; 1235 argv[1] = NULL; 1236 execve(shell, argv, env); 1237 1238 /* Executing the shell failed. */ 1239 perror(shell); 1240 exit(1); 1241 } 1242 /* 1243 * Execute the command using the user's shell. This uses the -c 1244 * option to execute the command. 1245 */ 1246 argv[0] = (char *) shell0; 1247 argv[1] = "-c"; 1248 argv[2] = (char *) command; 1249 argv[3] = NULL; 1250 execve(shell, argv, env); 1251 perror(shell); 1252 exit(1); 1253 } 1254 1255 Session * 1256 session_new(void) 1257 { 1258 int i; 1259 static int did_init = 0; 1260 if (!did_init) { 1261 debug("session_new: init"); 1262 for (i = 0; i < MAX_SESSIONS; i++) { 1263 sessions[i].used = 0; 1264 } 1265 did_init = 1; 1266 } 1267 for (i = 0; i < MAX_SESSIONS; i++) { 1268 Session *s = &sessions[i]; 1269 if (! s->used) { 1270 memset(s, 0, sizeof(*s)); 1271 s->chanid = -1; 1272 s->ptyfd = -1; 1273 s->ttyfd = -1; 1274 s->used = 1; 1275 s->self = i; 1276 debug("session_new: session %d", i); 1277 return s; 1278 } 1279 } 1280 return NULL; 1281 } 1282 1283 static void 1284 session_dump(void) 1285 { 1286 int i; 1287 for (i = 0; i < MAX_SESSIONS; i++) { 1288 Session *s = &sessions[i]; 1289 debug("dump: used %d session %d %p channel %d pid %ld", 1290 s->used, 1291 s->self, 1292 s, 1293 s->chanid, 1294 (long)s->pid); 1295 } 1296 } 1297 1298 int 1299 session_open(Authctxt *authctxt, int chanid) 1300 { 1301 Session *s = session_new(); 1302 debug("session_open: channel %d", chanid); 1303 if (s == NULL) { 1304 error("no more sessions"); 1305 return 0; 1306 } 1307 s->authctxt = authctxt; 1308 s->pw = authctxt->pw; 1309 if (s->pw == NULL || !authctxt->valid) 1310 fatal("no user for session %d", s->self); 1311 debug("session_open: session %d: link with channel %d", s->self, chanid); 1312 s->chanid = chanid; 1313 return 1; 1314 } 1315 1316 Session * 1317 session_by_tty(char *tty) 1318 { 1319 int i; 1320 for (i = 0; i < MAX_SESSIONS; i++) { 1321 Session *s = &sessions[i]; 1322 if (s->used && s->ttyfd != -1 && strcmp(s->tty, tty) == 0) { 1323 debug("session_by_tty: session %d tty %s", i, tty); 1324 return s; 1325 } 1326 } 1327 debug("session_by_tty: unknown tty %.100s", tty); 1328 session_dump(); 1329 return NULL; 1330 } 1331 1332 static Session * 1333 session_by_channel(int id) 1334 { 1335 int i; 1336 for (i = 0; i < MAX_SESSIONS; i++) { 1337 Session *s = &sessions[i]; 1338 if (s->used && s->chanid == id) { 1339 debug("session_by_channel: session %d channel %d", i, id); 1340 return s; 1341 } 1342 } 1343 debug("session_by_channel: unknown channel %d", id); 1344 session_dump(); 1345 return NULL; 1346 } 1347 1348 static Session * 1349 session_by_pid(pid_t pid) 1350 { 1351 int i; 1352 debug("session_by_pid: pid %ld", (long)pid); 1353 for (i = 0; i < MAX_SESSIONS; i++) { 1354 Session *s = &sessions[i]; 1355 if (s->used && s->pid == pid) 1356 return s; 1357 } 1358 error("session_by_pid: unknown pid %ld", (long)pid); 1359 session_dump(); 1360 return NULL; 1361 } 1362 1363 static int 1364 session_window_change_req(Session *s) 1365 { 1366 s->col = packet_get_int(); 1367 s->row = packet_get_int(); 1368 s->xpixel = packet_get_int(); 1369 s->ypixel = packet_get_int(); 1370 packet_check_eom(); 1371 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 1372 return 1; 1373 } 1374 1375 static int 1376 session_pty_req(Session *s) 1377 { 1378 u_int len; 1379 int n_bytes; 1380 1381 if (no_pty_flag) { 1382 debug("Allocating a pty not permitted for this authentication."); 1383 return 0; 1384 } 1385 if (s->ttyfd != -1) { 1386 packet_disconnect("Protocol error: you already have a pty."); 1387 return 0; 1388 } 1389 1390 s->term = packet_get_string(&len); 1391 1392 if (compat20) { 1393 s->col = packet_get_int(); 1394 s->row = packet_get_int(); 1395 } else { 1396 s->row = packet_get_int(); 1397 s->col = packet_get_int(); 1398 } 1399 s->xpixel = packet_get_int(); 1400 s->ypixel = packet_get_int(); 1401 1402 if (strcmp(s->term, "") == 0) { 1403 xfree(s->term); 1404 s->term = NULL; 1405 } 1406 1407 /* Allocate a pty and open it. */ 1408 debug("Allocating pty."); 1409 if (!PRIVSEP(pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty)))) { 1410 if (s->term) 1411 xfree(s->term); 1412 s->term = NULL; 1413 s->ptyfd = -1; 1414 s->ttyfd = -1; 1415 error("session_pty_req: session %d alloc failed", s->self); 1416 return 0; 1417 } 1418 debug("session_pty_req: session %d alloc %s", s->self, s->tty); 1419 1420 /* for SSH1 the tty modes length is not given */ 1421 if (!compat20) 1422 n_bytes = packet_remaining(); 1423 tty_parse_modes(s->ttyfd, &n_bytes); 1424 1425 if (!use_privsep) 1426 pty_setowner(s->pw, s->tty); 1427 1428 /* Set window size from the packet. */ 1429 pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); 1430 1431 packet_check_eom(); 1432 session_proctitle(s); 1433 return 1; 1434 } 1435 1436 static int 1437 session_subsystem_req(Session *s) 1438 { 1439 struct stat st; 1440 u_int len; 1441 int success = 0; 1442 char *cmd, *subsys = packet_get_string(&len); 1443 int i; 1444 1445 packet_check_eom(); 1446 logit("subsystem request for %.100s", subsys); 1447 1448 for (i = 0; i < options.num_subsystems; i++) { 1449 if (strcmp(subsys, options.subsystem_name[i]) == 0) { 1450 cmd = options.subsystem_command[i]; 1451 if (stat(cmd, &st) < 0) { 1452 error("subsystem: cannot stat %s: %s", cmd, 1453 strerror(errno)); 1454 break; 1455 } 1456 debug("subsystem: exec() %s", cmd); 1457 s->is_subsystem = 1; 1458 do_exec(s, cmd); 1459 success = 1; 1460 break; 1461 } 1462 } 1463 1464 if (!success) 1465 logit("subsystem request for %.100s failed, subsystem not found", 1466 subsys); 1467 1468 xfree(subsys); 1469 return success; 1470 } 1471 1472 static int 1473 session_x11_req(Session *s) 1474 { 1475 int success; 1476 1477 s->single_connection = packet_get_char(); 1478 s->auth_proto = packet_get_string(NULL); 1479 s->auth_data = packet_get_string(NULL); 1480 s->screen = packet_get_int(); 1481 packet_check_eom(); 1482 1483 success = session_setup_x11fwd(s); 1484 if (!success) { 1485 xfree(s->auth_proto); 1486 xfree(s->auth_data); 1487 s->auth_proto = NULL; 1488 s->auth_data = NULL; 1489 } 1490 return success; 1491 } 1492 1493 static int 1494 session_shell_req(Session *s) 1495 { 1496 packet_check_eom(); 1497 do_exec(s, NULL); 1498 return 1; 1499 } 1500 1501 static int 1502 session_exec_req(Session *s) 1503 { 1504 u_int len; 1505 char *command = packet_get_string(&len); 1506 packet_check_eom(); 1507 do_exec(s, command); 1508 xfree(command); 1509 return 1; 1510 } 1511 1512 static int 1513 session_break_req(Session *s) 1514 { 1515 1516 packet_get_int(); /* ignored */ 1517 packet_check_eom(); 1518 1519 if (s->ttyfd == -1 || 1520 tcsendbreak(s->ttyfd, 0) < 0) 1521 return 0; 1522 return 1; 1523 } 1524 1525 static int 1526 session_env_req(Session *s) 1527 { 1528 char *name, *val; 1529 u_int name_len, val_len, i; 1530 1531 name = packet_get_string(&name_len); 1532 val = packet_get_string(&val_len); 1533 packet_check_eom(); 1534 1535 /* Don't set too many environment variables */ 1536 if (s->num_env > 128) { 1537 debug2("Ignoring env request %s: too many env vars", name); 1538 goto fail; 1539 } 1540 1541 for (i = 0; i < options.num_accept_env; i++) { 1542 if (match_pattern(name, options.accept_env[i])) { 1543 debug2("Setting env %d: %s=%s", s->num_env, name, val); 1544 s->env = xrealloc(s->env, sizeof(*s->env) * 1545 (s->num_env + 1)); 1546 s->env[s->num_env].name = name; 1547 s->env[s->num_env].val = val; 1548 s->num_env++; 1549 return (1); 1550 } 1551 } 1552 debug2("Ignoring env request %s: disallowed name", name); 1553 1554 fail: 1555 xfree(name); 1556 xfree(val); 1557 return (0); 1558 } 1559 1560 static int 1561 session_auth_agent_req(Session *s) 1562 { 1563 static int called = 0; 1564 packet_check_eom(); 1565 if (no_agent_forwarding_flag) { 1566 debug("session_auth_agent_req: no_agent_forwarding_flag"); 1567 return 0; 1568 } 1569 if (called) { 1570 return 0; 1571 } else { 1572 called = 1; 1573 return auth_input_request_forwarding(s->pw); 1574 } 1575 } 1576 1577 int 1578 session_input_channel_req(Channel *c, const char *rtype) 1579 { 1580 int success = 0; 1581 Session *s; 1582 1583 if ((s = session_by_channel(c->self)) == NULL) { 1584 logit("session_input_channel_req: no session %d req %.100s", 1585 c->self, rtype); 1586 return 0; 1587 } 1588 debug("session_input_channel_req: session %d req %s", s->self, rtype); 1589 1590 /* 1591 * a session is in LARVAL state until a shell, a command 1592 * or a subsystem is executed 1593 */ 1594 if (c->type == SSH_CHANNEL_LARVAL) { 1595 if (strcmp(rtype, "shell") == 0) { 1596 success = session_shell_req(s); 1597 } else if (strcmp(rtype, "exec") == 0) { 1598 success = session_exec_req(s); 1599 } else if (strcmp(rtype, "pty-req") == 0) { 1600 success = session_pty_req(s); 1601 } else if (strcmp(rtype, "x11-req") == 0) { 1602 success = session_x11_req(s); 1603 } else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) { 1604 success = session_auth_agent_req(s); 1605 } else if (strcmp(rtype, "subsystem") == 0) { 1606 success = session_subsystem_req(s); 1607 } else if (strcmp(rtype, "env") == 0) { 1608 success = session_env_req(s); 1609 } 1610 } 1611 if (strcmp(rtype, "window-change") == 0) { 1612 success = session_window_change_req(s); 1613 } else if (strcmp(rtype, "break") == 0) { 1614 success = session_break_req(s); 1615 } 1616 1617 return success; 1618 } 1619 1620 void 1621 session_set_fds(Session *s, int fdin, int fdout, int fderr) 1622 { 1623 if (!compat20) 1624 fatal("session_set_fds: called for proto != 2.0"); 1625 /* 1626 * now that have a child and a pipe to the child, 1627 * we can activate our channel and register the fd's 1628 */ 1629 if (s->chanid == -1) 1630 fatal("no channel for session %d", s->self); 1631 channel_set_fds(s->chanid, 1632 fdout, fdin, fderr, 1633 fderr == -1 ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ, 1634 1, 1635 CHAN_SES_WINDOW_DEFAULT); 1636 } 1637 1638 /* 1639 * Function to perform pty cleanup. Also called if we get aborted abnormally 1640 * (e.g., due to a dropped connection). 1641 */ 1642 void 1643 session_pty_cleanup2(Session *s) 1644 { 1645 if (s == NULL) { 1646 error("session_pty_cleanup: no session"); 1647 return; 1648 } 1649 if (s->ttyfd == -1) 1650 return; 1651 1652 debug("session_pty_cleanup: session %d release %s", s->self, s->tty); 1653 1654 /* Record that the user has logged out. */ 1655 if (s->pid != 0) 1656 record_logout(s->pid, s->tty); 1657 1658 /* Release the pseudo-tty. */ 1659 if (getuid() == 0) 1660 pty_release(s->tty); 1661 1662 /* 1663 * Close the server side of the socket pairs. We must do this after 1664 * the pty cleanup, so that another process doesn't get this pty 1665 * while we're still cleaning up. 1666 */ 1667 if (close(s->ptymaster) < 0) 1668 error("close(s->ptymaster/%d): %s", s->ptymaster, strerror(errno)); 1669 1670 /* unlink pty from session */ 1671 s->ttyfd = -1; 1672 } 1673 1674 void 1675 session_pty_cleanup(Session *s) 1676 { 1677 PRIVSEP(session_pty_cleanup2(s)); 1678 } 1679 1680 static char * 1681 sig2name(int sig) 1682 { 1683 #define SSH_SIG(x) if (sig == SIG ## x) return #x 1684 SSH_SIG(ABRT); 1685 SSH_SIG(ALRM); 1686 SSH_SIG(FPE); 1687 SSH_SIG(HUP); 1688 SSH_SIG(ILL); 1689 SSH_SIG(INT); 1690 SSH_SIG(KILL); 1691 SSH_SIG(PIPE); 1692 SSH_SIG(QUIT); 1693 SSH_SIG(SEGV); 1694 SSH_SIG(TERM); 1695 SSH_SIG(USR1); 1696 SSH_SIG(USR2); 1697 #undef SSH_SIG 1698 return "SIG@openssh.com"; 1699 } 1700 1701 static void 1702 session_exit_message(Session *s, int status) 1703 { 1704 Channel *c; 1705 1706 if ((c = channel_lookup(s->chanid)) == NULL) 1707 fatal("session_exit_message: session %d: no channel %d", 1708 s->self, s->chanid); 1709 debug("session_exit_message: session %d channel %d pid %ld", 1710 s->self, s->chanid, (long)s->pid); 1711 1712 if (WIFEXITED(status)) { 1713 channel_request_start(s->chanid, "exit-status", 0); 1714 packet_put_int(WEXITSTATUS(status)); 1715 packet_send(); 1716 } else if (WIFSIGNALED(status)) { 1717 channel_request_start(s->chanid, "exit-signal", 0); 1718 packet_put_cstring(sig2name(WTERMSIG(status))); 1719 packet_put_char(WCOREDUMP(status)); 1720 packet_put_cstring(""); 1721 packet_put_cstring(""); 1722 packet_send(); 1723 } else { 1724 /* Some weird exit cause. Just exit. */ 1725 packet_disconnect("wait returned status %04x.", status); 1726 } 1727 1728 /* disconnect channel */ 1729 debug("session_exit_message: release channel %d", s->chanid); 1730 channel_cancel_cleanup(s->chanid); 1731 /* 1732 * emulate a write failure with 'chan_write_failed', nobody will be 1733 * interested in data we write. 1734 * Note that we must not call 'chan_read_failed', since there could 1735 * be some more data waiting in the pipe. 1736 */ 1737 if (c->ostate != CHAN_OUTPUT_CLOSED) 1738 chan_write_failed(c); 1739 s->chanid = -1; 1740 } 1741 1742 void 1743 session_close(Session *s) 1744 { 1745 int i; 1746 1747 debug("session_close: session %d pid %ld", s->self, (long)s->pid); 1748 if (s->ttyfd != -1) 1749 session_pty_cleanup(s); 1750 if (s->term) 1751 xfree(s->term); 1752 if (s->display) 1753 xfree(s->display); 1754 if (s->auth_display) 1755 xfree(s->auth_display); 1756 if (s->auth_data) 1757 xfree(s->auth_data); 1758 if (s->auth_proto) 1759 xfree(s->auth_proto); 1760 s->used = 0; 1761 for (i = 0; i < s->num_env; i++) { 1762 xfree(s->env[i].name); 1763 xfree(s->env[i].val); 1764 } 1765 if (s->env != NULL) 1766 xfree(s->env); 1767 session_proctitle(s); 1768 } 1769 1770 void 1771 session_close_by_pid(pid_t pid, int status) 1772 { 1773 Session *s = session_by_pid(pid); 1774 if (s == NULL) { 1775 debug("session_close_by_pid: no session for pid %ld", 1776 (long)pid); 1777 return; 1778 } 1779 if (s->chanid != -1) 1780 session_exit_message(s, status); 1781 session_close(s); 1782 } 1783 1784 /* 1785 * this is called when a channel dies before 1786 * the session 'child' itself dies 1787 */ 1788 void 1789 session_close_by_channel(int id, void *arg) 1790 { 1791 Session *s = session_by_channel(id); 1792 if (s == NULL) { 1793 debug("session_close_by_channel: no session for id %d", id); 1794 return; 1795 } 1796 debug("session_close_by_channel: channel %d child %ld", 1797 id, (long)s->pid); 1798 if (s->pid != 0) { 1799 debug("session_close_by_channel: channel %d: has child", id); 1800 /* 1801 * delay detach of session, but release pty, since 1802 * the fd's to the child are already closed 1803 */ 1804 if (s->ttyfd != -1) 1805 session_pty_cleanup(s); 1806 return; 1807 } 1808 /* detach by removing callback */ 1809 channel_cancel_cleanup(s->chanid); 1810 s->chanid = -1; 1811 session_close(s); 1812 } 1813 1814 void 1815 session_destroy_all(void (*closefunc)(Session *)) 1816 { 1817 int i; 1818 for (i = 0; i < MAX_SESSIONS; i++) { 1819 Session *s = &sessions[i]; 1820 if (s->used) { 1821 if (closefunc != NULL) 1822 closefunc(s); 1823 else 1824 session_close(s); 1825 } 1826 } 1827 } 1828 1829 static char * 1830 session_tty_list(void) 1831 { 1832 static char buf[1024]; 1833 int i; 1834 buf[0] = '\0'; 1835 for (i = 0; i < MAX_SESSIONS; i++) { 1836 Session *s = &sessions[i]; 1837 if (s->used && s->ttyfd != -1) { 1838 if (buf[0] != '\0') 1839 strlcat(buf, ",", sizeof buf); 1840 strlcat(buf, strrchr(s->tty, '/') + 1, sizeof buf); 1841 } 1842 } 1843 if (buf[0] == '\0') 1844 strlcpy(buf, "notty", sizeof buf); 1845 return buf; 1846 } 1847 1848 void 1849 session_proctitle(Session *s) 1850 { 1851 if (s->pw == NULL) 1852 error("no user for session %d", s->self); 1853 else 1854 setproctitle("%s@%s", s->pw->pw_name, session_tty_list()); 1855 } 1856 1857 int 1858 session_setup_x11fwd(Session *s) 1859 { 1860 struct stat st; 1861 char display[512], auth_display[512]; 1862 char hostname[MAXHOSTNAMELEN]; 1863 1864 if (no_x11_forwarding_flag) { 1865 packet_send_debug("X11 forwarding disabled in user configuration file."); 1866 return 0; 1867 } 1868 if (!options.x11_forwarding) { 1869 debug("X11 forwarding disabled in server configuration file."); 1870 return 0; 1871 } 1872 if (!options.xauth_location || 1873 (stat(options.xauth_location, &st) == -1)) { 1874 packet_send_debug("No xauth program; cannot forward with spoofing."); 1875 return 0; 1876 } 1877 if (options.use_login) { 1878 packet_send_debug("X11 forwarding disabled; " 1879 "not compatible with UseLogin=yes."); 1880 return 0; 1881 } 1882 if (s->display != NULL) { 1883 debug("X11 display already set."); 1884 return 0; 1885 } 1886 if (x11_create_display_inet(options.x11_display_offset, 1887 options.x11_use_localhost, s->single_connection, 1888 &s->display_number) == -1) { 1889 debug("x11_create_display_inet failed."); 1890 return 0; 1891 } 1892 1893 /* Set up a suitable value for the DISPLAY variable. */ 1894 if (gethostname(hostname, sizeof(hostname)) < 0) 1895 fatal("gethostname: %.100s", strerror(errno)); 1896 /* 1897 * auth_display must be used as the displayname when the 1898 * authorization entry is added with xauth(1). This will be 1899 * different than the DISPLAY string for localhost displays. 1900 */ 1901 if (options.x11_use_localhost) { 1902 snprintf(display, sizeof display, "localhost:%u.%u", 1903 s->display_number, s->screen); 1904 snprintf(auth_display, sizeof auth_display, "unix:%u.%u", 1905 s->display_number, s->screen); 1906 s->display = xstrdup(display); 1907 s->auth_display = xstrdup(auth_display); 1908 } else { 1909 snprintf(display, sizeof display, "%.400s:%u.%u", hostname, 1910 s->display_number, s->screen); 1911 s->display = xstrdup(display); 1912 s->auth_display = xstrdup(display); 1913 } 1914 1915 return 1; 1916 } 1917 1918 static void 1919 do_authenticated2(Authctxt *authctxt) 1920 { 1921 server_loop2(authctxt); 1922 } 1923 1924 void 1925 do_cleanup(Authctxt *authctxt) 1926 { 1927 static int called = 0; 1928 1929 debug("do_cleanup"); 1930 1931 /* no cleanup if we're in the child for login shell */ 1932 if (is_child) 1933 return; 1934 1935 /* avoid double cleanup */ 1936 if (called) 1937 return; 1938 called = 1; 1939 1940 if (authctxt == NULL) 1941 return; 1942 #ifdef KRB5 1943 if (options.kerberos_ticket_cleanup && 1944 authctxt->krb5_ctx) 1945 krb5_cleanup_proc(authctxt); 1946 #endif 1947 1948 #ifdef GSSAPI 1949 if (compat20 && options.gss_cleanup_creds) 1950 ssh_gssapi_cleanup_creds(); 1951 #endif 1952 1953 /* remove agent socket */ 1954 auth_sock_cleanup_proc(authctxt->pw); 1955 1956 /* 1957 * Cleanup ptys/utmp only if privsep is disabled, 1958 * or if running in monitor. 1959 */ 1960 if (!use_privsep || mm_is_monitor()) 1961 session_destroy_all(session_pty_cleanup2); 1962 } 1963