xref: /dragonfly/crypto/openssh/session.c (revision 984263bc)
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 1.150 2002/09/16 19:55:33 stevesk Exp $");
37 RCSID("$FreeBSD: src/crypto/openssh/session.c,v 1.4.2.17 2003/02/03 17:31:07 des Exp $");
38 
39 #include "ssh.h"
40 #include "ssh1.h"
41 #include "ssh2.h"
42 #include "xmalloc.h"
43 #include "sshpty.h"
44 #include "packet.h"
45 #include "buffer.h"
46 #include "mpaux.h"
47 #include "uidswap.h"
48 #include "compat.h"
49 #include "channels.h"
50 #include "bufaux.h"
51 #include "auth.h"
52 #include "auth-options.h"
53 #include "pathnames.h"
54 #include "log.h"
55 #include "servconf.h"
56 #include "sshlogin.h"
57 #include "serverloop.h"
58 #include "canohost.h"
59 #include "session.h"
60 #include "monitor_wrap.h"
61 
62 #ifdef HAVE_CYGWIN
63 #include <windows.h>
64 #include <sys/cygwin.h>
65 #define is_winnt       (GetVersion() < 0x80000000)
66 #endif
67 
68 /* func */
69 
70 Session *session_new(void);
71 void	session_set_fds(Session *, int, int, int);
72 void	session_pty_cleanup(void *);
73 void	session_proctitle(Session *);
74 int	session_setup_x11fwd(Session *);
75 void	do_exec_pty(Session *, const char *);
76 void	do_exec_no_pty(Session *, const char *);
77 void	do_exec(Session *, const char *);
78 void	do_login(Session *, const char *);
79 #ifdef LOGIN_NEEDS_UTMPX
80 static void	do_pre_login(Session *s);
81 #endif
82 void	do_child(Session *, const char *);
83 void	do_motd(void);
84 int	check_quietlogin(Session *, const char *);
85 
86 static void do_authenticated1(Authctxt *);
87 static void do_authenticated2(Authctxt *);
88 
89 static int session_pty_req(Session *);
90 
91 /* import */
92 extern ServerOptions options;
93 extern char *__progname;
94 extern int log_stderr;
95 extern int debug_flag;
96 extern u_int utmp_len;
97 extern int startup_pipe;
98 extern void destroy_sensitive_data(void);
99 
100 /* original command from peer. */
101 const char *original_command = NULL;
102 
103 /* data */
104 #define MAX_SESSIONS 10
105 Session	sessions[MAX_SESSIONS];
106 
107 #ifdef WITH_AIXAUTHENTICATE
108 char *aixloginmsg;
109 #endif /* WITH_AIXAUTHENTICATE */
110 
111 #ifdef HAVE_LOGIN_CAP
112 login_cap_t *lc;
113 #endif
114 
115 /* Name and directory of socket for authentication agent forwarding. */
116 static char *auth_sock_name = NULL;
117 static char *auth_sock_dir = NULL;
118 
119 /* removes the agent forwarding socket */
120 
121 static void
122 auth_sock_cleanup_proc(void *_pw)
123 {
124 	struct passwd *pw = _pw;
125 
126 	if (auth_sock_name != NULL) {
127 		temporarily_use_uid(pw);
128 		unlink(auth_sock_name);
129 		rmdir(auth_sock_dir);
130 		auth_sock_name = NULL;
131 		restore_uid();
132 	}
133 }
134 
135 static int
136 auth_input_request_forwarding(struct passwd * pw)
137 {
138 	Channel *nc;
139 	int sock;
140 	struct sockaddr_un sunaddr;
141 
142 	if (auth_sock_name != NULL) {
143 		error("authentication forwarding requested twice.");
144 		return 0;
145 	}
146 
147 	/* Temporarily drop privileged uid for mkdir/bind. */
148 	temporarily_use_uid(pw);
149 
150 	/* Allocate a buffer for the socket name, and format the name. */
151 	auth_sock_name = xmalloc(MAXPATHLEN);
152 	auth_sock_dir = xmalloc(MAXPATHLEN);
153 	strlcpy(auth_sock_dir, "/tmp/ssh-XXXXXXXX", MAXPATHLEN);
154 
155 	/* Create private directory for socket */
156 	if (mkdtemp(auth_sock_dir) == NULL) {
157 		packet_send_debug("Agent forwarding disabled: "
158 		    "mkdtemp() failed: %.100s", strerror(errno));
159 		restore_uid();
160 		xfree(auth_sock_name);
161 		xfree(auth_sock_dir);
162 		auth_sock_name = NULL;
163 		auth_sock_dir = NULL;
164 		return 0;
165 	}
166 	snprintf(auth_sock_name, MAXPATHLEN, "%s/agent.%ld",
167 		 auth_sock_dir, (long) getpid());
168 
169 	/* delete agent socket on fatal() */
170 	fatal_add_cleanup(auth_sock_cleanup_proc, pw);
171 
172 	/* Create the socket. */
173 	sock = socket(AF_UNIX, SOCK_STREAM, 0);
174 	if (sock < 0)
175 		packet_disconnect("socket: %.100s", strerror(errno));
176 
177 	/* Bind it to the name. */
178 	memset(&sunaddr, 0, sizeof(sunaddr));
179 	sunaddr.sun_family = AF_UNIX;
180 	strlcpy(sunaddr.sun_path, auth_sock_name, sizeof(sunaddr.sun_path));
181 
182 	if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0)
183 		packet_disconnect("bind: %.100s", strerror(errno));
184 
185 	/* Restore the privileged uid. */
186 	restore_uid();
187 
188 	/* Start listening on the socket. */
189 	if (listen(sock, 5) < 0)
190 		packet_disconnect("listen: %.100s", strerror(errno));
191 
192 	/* Allocate a channel for the authentication agent socket. */
193 	nc = channel_new("auth socket",
194 	    SSH_CHANNEL_AUTH_SOCKET, sock, sock, -1,
195 	    CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
196 	    0, xstrdup("auth socket"), 1);
197 	strlcpy(nc->path, auth_sock_name, sizeof(nc->path));
198 	return 1;
199 }
200 
201 
202 void
203 do_authenticated(Authctxt *authctxt)
204 {
205 	/*
206 	 * Cancel the alarm we set to limit the time taken for
207 	 * authentication.
208 	 */
209 	alarm(0);
210 	if (startup_pipe != -1) {
211 		close(startup_pipe);
212 		startup_pipe = -1;
213 	}
214 
215 	/* setup the channel layer */
216 	if (!no_port_forwarding_flag && options.allow_tcp_forwarding)
217 		channel_permit_all_opens();
218 
219 	if (compat20)
220 		do_authenticated2(authctxt);
221 	else
222 		do_authenticated1(authctxt);
223 
224 	/* remove agent socket */
225 	if (auth_sock_name != NULL)
226 		auth_sock_cleanup_proc(authctxt->pw);
227 #ifdef KRB4
228 	if (options.kerberos_ticket_cleanup)
229 		krb4_cleanup_proc(authctxt);
230 #endif
231 #ifdef KRB5
232 	if (options.kerberos_ticket_cleanup)
233 		krb5_cleanup_proc(authctxt);
234 #endif
235 }
236 
237 /*
238  * Prepares for an interactive session.  This is called after the user has
239  * been successfully authenticated.  During this message exchange, pseudo
240  * terminals are allocated, X11, TCP/IP, and authentication agent forwardings
241  * are requested, etc.
242  */
243 static void
244 do_authenticated1(Authctxt *authctxt)
245 {
246 	Session *s;
247 	char *command;
248 	int success, type, screen_flag;
249 	int enable_compression_after_reply = 0;
250 	u_int proto_len, data_len, dlen, compression_level = 0;
251 
252 	s = session_new();
253 	s->authctxt = authctxt;
254 	s->pw = authctxt->pw;
255 
256 	/*
257 	 * We stay in this loop until the client requests to execute a shell
258 	 * or a command.
259 	 */
260 	for (;;) {
261 		success = 0;
262 
263 		/* Get a packet from the client. */
264 		type = packet_read();
265 
266 		/* Process the packet. */
267 		switch (type) {
268 		case SSH_CMSG_REQUEST_COMPRESSION:
269 			compression_level = packet_get_int();
270 			packet_check_eom();
271 			if (compression_level < 1 || compression_level > 9) {
272 				packet_send_debug("Received illegal compression level %d.",
273 				    compression_level);
274 				break;
275 			}
276 			if (!options.compression) {
277 				debug2("compression disabled");
278 				break;
279 			}
280 			/* Enable compression after we have responded with SUCCESS. */
281 			enable_compression_after_reply = 1;
282 			success = 1;
283 			break;
284 
285 		case SSH_CMSG_REQUEST_PTY:
286 			success = session_pty_req(s);
287 			break;
288 
289 		case SSH_CMSG_X11_REQUEST_FORWARDING:
290 			s->auth_proto = packet_get_string(&proto_len);
291 			s->auth_data = packet_get_string(&data_len);
292 
293 			screen_flag = packet_get_protocol_flags() &
294 			    SSH_PROTOFLAG_SCREEN_NUMBER;
295 			debug2("SSH_PROTOFLAG_SCREEN_NUMBER: %d", screen_flag);
296 
297 			if (packet_remaining() == 4) {
298 				if (!screen_flag)
299 					debug2("Buggy client: "
300 					    "X11 screen flag missing");
301 				s->screen = packet_get_int();
302 			} else {
303 				s->screen = 0;
304 			}
305 			packet_check_eom();
306 			success = session_setup_x11fwd(s);
307 			if (!success) {
308 				xfree(s->auth_proto);
309 				xfree(s->auth_data);
310 				s->auth_proto = NULL;
311 				s->auth_data = NULL;
312 			}
313 			break;
314 
315 		case SSH_CMSG_AGENT_REQUEST_FORWARDING:
316 			if (no_agent_forwarding_flag || compat13) {
317 				debug("Authentication agent forwarding not permitted for this authentication.");
318 				break;
319 			}
320 			debug("Received authentication agent forwarding request.");
321 			success = auth_input_request_forwarding(s->pw);
322 			break;
323 
324 		case SSH_CMSG_PORT_FORWARD_REQUEST:
325 			if (no_port_forwarding_flag) {
326 				debug("Port forwarding not permitted for this authentication.");
327 				break;
328 			}
329 			if (!options.allow_tcp_forwarding) {
330 				debug("Port forwarding not permitted.");
331 				break;
332 			}
333 			debug("Received TCP/IP port forwarding request.");
334 			channel_input_port_forward_request(s->pw->pw_uid == 0, options.gateway_ports);
335 			success = 1;
336 			break;
337 
338 		case SSH_CMSG_MAX_PACKET_SIZE:
339 			if (packet_set_maxsize(packet_get_int()) > 0)
340 				success = 1;
341 			break;
342 
343 #if defined(AFS) || defined(KRB5)
344 		case SSH_CMSG_HAVE_KERBEROS_TGT:
345 			if (!options.kerberos_tgt_passing) {
346 				verbose("Kerberos TGT passing disabled.");
347 			} else {
348 				char *kdata = packet_get_string(&dlen);
349 				packet_check_eom();
350 
351 				/* XXX - 0x41, see creds_to_radix version */
352 				if (kdata[0] != 0x41) {
353 #ifdef KRB5
354 					krb5_data tgt;
355 					tgt.data = kdata;
356 					tgt.length = dlen;
357 
358 					if (auth_krb5_tgt(s->authctxt, &tgt))
359 						success = 1;
360 					else
361 						verbose("Kerberos v5 TGT refused for %.100s", s->authctxt->user);
362 #endif /* KRB5 */
363 				} else {
364 #ifdef AFS
365 					if (auth_krb4_tgt(s->authctxt, kdata))
366 						success = 1;
367 					else
368 						verbose("Kerberos v4 TGT refused for %.100s", s->authctxt->user);
369 #endif /* AFS */
370 				}
371 				xfree(kdata);
372 			}
373 			break;
374 #endif /* AFS || KRB5 */
375 
376 #ifdef AFS
377 		case SSH_CMSG_HAVE_AFS_TOKEN:
378 			if (!options.afs_token_passing || !k_hasafs()) {
379 				verbose("AFS token passing disabled.");
380 			} else {
381 				/* Accept AFS token. */
382 				char *token = packet_get_string(&dlen);
383 				packet_check_eom();
384 
385 				if (auth_afs_token(s->authctxt, token))
386 					success = 1;
387 				else
388 					verbose("AFS token refused for %.100s",
389 					    s->authctxt->user);
390 				xfree(token);
391 			}
392 			break;
393 #endif /* AFS */
394 
395 		case SSH_CMSG_EXEC_SHELL:
396 		case SSH_CMSG_EXEC_CMD:
397 			if (type == SSH_CMSG_EXEC_CMD) {
398 				command = packet_get_string(&dlen);
399 				debug("Exec command '%.500s'", command);
400 				do_exec(s, command);
401 				xfree(command);
402 			} else {
403 				do_exec(s, NULL);
404 			}
405 			packet_check_eom();
406 			session_close(s);
407 			return;
408 
409 		default:
410 			/*
411 			 * Any unknown messages in this phase are ignored,
412 			 * and a failure message is returned.
413 			 */
414 			log("Unknown packet type received after authentication: %d", type);
415 		}
416 		packet_start(success ? SSH_SMSG_SUCCESS : SSH_SMSG_FAILURE);
417 		packet_send();
418 		packet_write_wait();
419 
420 		/* Enable compression now that we have replied if appropriate. */
421 		if (enable_compression_after_reply) {
422 			enable_compression_after_reply = 0;
423 			packet_start_compression(compression_level);
424 		}
425 	}
426 }
427 
428 /*
429  * This is called to fork and execute a command when we have no tty.  This
430  * will call do_child from the child, and server_loop from the parent after
431  * setting up file descriptors and such.
432  */
433 void
434 do_exec_no_pty(Session *s, const char *command)
435 {
436 	pid_t pid;
437 
438 #ifdef USE_PIPES
439 	int pin[2], pout[2], perr[2];
440 	/* Allocate pipes for communicating with the program. */
441 	if (pipe(pin) < 0 || pipe(pout) < 0 || pipe(perr) < 0)
442 		packet_disconnect("Could not create pipes: %.100s",
443 				  strerror(errno));
444 #else /* USE_PIPES */
445 	int inout[2], err[2];
446 	/* Uses socket pairs to communicate with the program. */
447 	if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) < 0 ||
448 	    socketpair(AF_UNIX, SOCK_STREAM, 0, err) < 0)
449 		packet_disconnect("Could not create socket pairs: %.100s",
450 				  strerror(errno));
451 #endif /* USE_PIPES */
452 	if (s == NULL)
453 		fatal("do_exec_no_pty: no session");
454 
455 	session_proctitle(s);
456 
457 #if defined(USE_PAM)
458 	do_pam_session(s->pw->pw_name, NULL);
459 	do_pam_setcred(1);
460 	if (is_pam_password_change_required())
461 		packet_disconnect("Password change required but no "
462 		    "TTY available");
463 #endif /* USE_PAM */
464 
465 	/* Fork the child. */
466 	if ((pid = fork()) == 0) {
467 		fatal_remove_all_cleanups();
468 
469 		/* Child.  Reinitialize the log since the pid has changed. */
470 		log_init(__progname, options.log_level, options.log_facility, log_stderr);
471 
472 		/*
473 		 * Create a new session and process group since the 4.4BSD
474 		 * setlogin() affects the entire process group.
475 		 */
476 		if (setsid() < 0)
477 			error("setsid failed: %.100s", strerror(errno));
478 
479 #ifdef USE_PIPES
480 		/*
481 		 * Redirect stdin.  We close the parent side of the socket
482 		 * pair, and make the child side the standard input.
483 		 */
484 		close(pin[1]);
485 		if (dup2(pin[0], 0) < 0)
486 			perror("dup2 stdin");
487 		close(pin[0]);
488 
489 		/* Redirect stdout. */
490 		close(pout[0]);
491 		if (dup2(pout[1], 1) < 0)
492 			perror("dup2 stdout");
493 		close(pout[1]);
494 
495 		/* Redirect stderr. */
496 		close(perr[0]);
497 		if (dup2(perr[1], 2) < 0)
498 			perror("dup2 stderr");
499 		close(perr[1]);
500 #else /* USE_PIPES */
501 		/*
502 		 * Redirect stdin, stdout, and stderr.  Stdin and stdout will
503 		 * use the same socket, as some programs (particularly rdist)
504 		 * seem to depend on it.
505 		 */
506 		close(inout[1]);
507 		close(err[1]);
508 		if (dup2(inout[0], 0) < 0)	/* stdin */
509 			perror("dup2 stdin");
510 		if (dup2(inout[0], 1) < 0)	/* stdout.  Note: same socket as stdin. */
511 			perror("dup2 stdout");
512 		if (dup2(err[0], 2) < 0)	/* stderr */
513 			perror("dup2 stderr");
514 #endif /* USE_PIPES */
515 
516 #ifdef _UNICOS
517 		cray_init_job(s->pw); /* set up cray jid and tmpdir */
518 #endif
519 
520 		/* Do processing for the child (exec command etc). */
521 		do_child(s, command);
522 		/* NOTREACHED */
523 	}
524 #ifdef _UNICOS
525 	signal(WJSIGNAL, cray_job_termination_handler);
526 #endif /* _UNICOS */
527 #ifdef HAVE_CYGWIN
528 	if (is_winnt)
529 		cygwin_set_impersonation_token(INVALID_HANDLE_VALUE);
530 #endif
531 	if (pid < 0)
532 		packet_disconnect("fork failed: %.100s", strerror(errno));
533 	s->pid = pid;
534 	/* Set interactive/non-interactive mode. */
535 	packet_set_interactive(s->display != NULL);
536 #ifdef USE_PIPES
537 	/* We are the parent.  Close the child sides of the pipes. */
538 	close(pin[0]);
539 	close(pout[1]);
540 	close(perr[1]);
541 
542 	if (compat20) {
543 		session_set_fds(s, pin[1], pout[0], s->is_subsystem ? -1 : perr[0]);
544 	} else {
545 		/* Enter the interactive session. */
546 		server_loop(pid, pin[1], pout[0], perr[0]);
547 		/* server_loop has closed pin[1], pout[0], and perr[0]. */
548 	}
549 #else /* USE_PIPES */
550 	/* We are the parent.  Close the child sides of the socket pairs. */
551 	close(inout[0]);
552 	close(err[0]);
553 
554 	/*
555 	 * Enter the interactive session.  Note: server_loop must be able to
556 	 * handle the case that fdin and fdout are the same.
557 	 */
558 	if (compat20) {
559 		session_set_fds(s, inout[1], inout[1], s->is_subsystem ? -1 : err[1]);
560 	} else {
561 		server_loop(pid, inout[1], inout[1], err[1]);
562 		/* server_loop has closed inout[1] and err[1]. */
563 	}
564 #endif /* USE_PIPES */
565 }
566 
567 /*
568  * This is called to fork and execute a command when we have a tty.  This
569  * will call do_child from the child, and server_loop from the parent after
570  * setting up file descriptors, controlling tty, updating wtmp, utmp,
571  * lastlog, and other such operations.
572  */
573 void
574 do_exec_pty(Session *s, const char *command)
575 {
576 	int fdout, ptyfd, ttyfd, ptymaster;
577 	pid_t pid;
578 
579 	if (s == NULL)
580 		fatal("do_exec_pty: no session");
581 	ptyfd = s->ptyfd;
582 	ttyfd = s->ttyfd;
583 
584 #if defined(USE_PAM)
585 	do_pam_session(s->pw->pw_name, s->tty);
586 	do_pam_setcred(1);
587 #endif
588 
589 	/* Fork the child. */
590 	if ((pid = fork()) == 0) {
591 		fatal_remove_all_cleanups();
592 
593 		/* Child.  Reinitialize the log because the pid has changed. */
594 		log_init(__progname, options.log_level, options.log_facility, log_stderr);
595 		/* Close the master side of the pseudo tty. */
596 		close(ptyfd);
597 
598 		/* Make the pseudo tty our controlling tty. */
599 		pty_make_controlling_tty(&ttyfd, s->tty);
600 
601 		/* Redirect stdin/stdout/stderr from the pseudo tty. */
602 		if (dup2(ttyfd, 0) < 0)
603 			error("dup2 stdin: %s", strerror(errno));
604 		if (dup2(ttyfd, 1) < 0)
605 			error("dup2 stdout: %s", strerror(errno));
606 		if (dup2(ttyfd, 2) < 0)
607 			error("dup2 stderr: %s", strerror(errno));
608 
609 		/* Close the extra descriptor for the pseudo tty. */
610 		close(ttyfd);
611 
612 		/* record login, etc. similar to login(1) */
613 #ifndef HAVE_OSF_SIA
614 		if (!(options.use_login && command == NULL)) {
615 #ifdef _UNICOS
616 			cray_init_job(s->pw); /* set up cray jid and tmpdir */
617 #endif /* _UNICOS */
618 			do_login(s, command);
619 		}
620 # ifdef LOGIN_NEEDS_UTMPX
621 		else
622 			do_pre_login(s);
623 # endif
624 #endif
625 
626 		/* Do common processing for the child, such as execing the command. */
627 		do_child(s, command);
628 		/* NOTREACHED */
629 	}
630 #ifdef _UNICOS
631 	signal(WJSIGNAL, cray_job_termination_handler);
632 #endif /* _UNICOS */
633 #ifdef HAVE_CYGWIN
634 	if (is_winnt)
635 		cygwin_set_impersonation_token(INVALID_HANDLE_VALUE);
636 #endif
637 	if (pid < 0)
638 		packet_disconnect("fork failed: %.100s", strerror(errno));
639 	s->pid = pid;
640 
641 	/* Parent.  Close the slave side of the pseudo tty. */
642 	close(ttyfd);
643 
644 	/*
645 	 * Create another descriptor of the pty master side for use as the
646 	 * standard input.  We could use the original descriptor, but this
647 	 * simplifies code in server_loop.  The descriptor is bidirectional.
648 	 */
649 	fdout = dup(ptyfd);
650 	if (fdout < 0)
651 		packet_disconnect("dup #1 failed: %.100s", strerror(errno));
652 
653 	/* we keep a reference to the pty master */
654 	ptymaster = dup(ptyfd);
655 	if (ptymaster < 0)
656 		packet_disconnect("dup #2 failed: %.100s", strerror(errno));
657 	s->ptymaster = ptymaster;
658 
659 	/* Enter interactive session. */
660 	packet_set_interactive(1);
661 	if (compat20) {
662 		session_set_fds(s, ptyfd, fdout, -1);
663 	} else {
664 		server_loop(pid, ptyfd, fdout, -1);
665 		/* server_loop _has_ closed ptyfd and fdout. */
666 	}
667 }
668 
669 #ifdef LOGIN_NEEDS_UTMPX
670 static void
671 do_pre_login(Session *s)
672 {
673 	socklen_t fromlen;
674 	struct sockaddr_storage from;
675 	pid_t pid = getpid();
676 
677 	/*
678 	 * Get IP address of client. If the connection is not a socket, let
679 	 * the address be 0.0.0.0.
680 	 */
681 	memset(&from, 0, sizeof(from));
682 	fromlen = sizeof(from);
683 	if (packet_connection_is_on_socket()) {
684 		if (getpeername(packet_get_connection_in(),
685 		    (struct sockaddr *) & from, &fromlen) < 0) {
686 			debug("getpeername: %.100s", strerror(errno));
687 			fatal_cleanup();
688 		}
689 	}
690 
691 	record_utmp_only(pid, s->tty, s->pw->pw_name,
692 	    get_remote_name_or_ip(utmp_len, options.verify_reverse_mapping),
693 	    (struct sockaddr *)&from, fromlen);
694 }
695 #endif
696 
697 /*
698  * This is called to fork and execute a command.  If another command is
699  * to be forced, execute that instead.
700  */
701 void
702 do_exec(Session *s, const char *command)
703 {
704 	if (forced_command) {
705 		original_command = command;
706 		command = forced_command;
707 		debug("Forced command '%.900s'", command);
708 	}
709 
710 	if (s->ttyfd != -1)
711 		do_exec_pty(s, command);
712 	else
713 		do_exec_no_pty(s, command);
714 
715 	original_command = NULL;
716 }
717 
718 
719 /* administrative, login(1)-like work */
720 void
721 do_login(Session *s, const char *command)
722 {
723 	char *time_string;
724 	socklen_t fromlen;
725 	struct sockaddr_storage from;
726 	struct passwd * pw = s->pw;
727 	pid_t pid = getpid();
728 
729 	/*
730 	 * Get IP address of client. If the connection is not a socket, let
731 	 * the address be 0.0.0.0.
732 	 */
733 	memset(&from, 0, sizeof(from));
734 	fromlen = sizeof(from);
735 	if (packet_connection_is_on_socket()) {
736 		if (getpeername(packet_get_connection_in(),
737 		    (struct sockaddr *) & from, &fromlen) < 0) {
738 			debug("getpeername: %.100s", strerror(errno));
739 			fatal_cleanup();
740 		}
741 	}
742 
743 	/* Record that there was a login on that tty from the remote host. */
744 	if (!use_privsep)
745 		record_login(pid, s->tty, pw->pw_name, pw->pw_uid,
746 		    get_remote_name_or_ip(utmp_len,
747 		    options.verify_reverse_mapping),
748 		    (struct sockaddr *)&from, fromlen);
749 
750 #ifdef USE_PAM
751 	/*
752 	 * If password change is needed, do it now.
753 	 * This needs to occur before the ~/.hushlogin check.
754 	 */
755 	if (is_pam_password_change_required()) {
756 		print_pam_messages();
757 		do_pam_chauthtok();
758 	}
759 #endif
760 
761 	if (check_quietlogin(s, command))
762 		return;
763 
764 #ifdef USE_PAM
765 	if (!is_pam_password_change_required())
766 		print_pam_messages();
767 #endif /* USE_PAM */
768 #ifdef WITH_AIXAUTHENTICATE
769 	if (aixloginmsg && *aixloginmsg)
770 		printf("%s\n", aixloginmsg);
771 #endif /* WITH_AIXAUTHENTICATE */
772 
773 #ifndef NO_SSH_LASTLOG
774 	if (options.print_lastlog && s->last_login_time != 0) {
775 		time_string = ctime(&s->last_login_time);
776 		if (strchr(time_string, '\n'))
777 			*strchr(time_string, '\n') = 0;
778 		if (strcmp(s->hostname, "") == 0)
779 			printf("Last login: %s\r\n", time_string);
780 		else
781 			printf("Last login: %s from %s\r\n", time_string,
782 			    s->hostname);
783 	}
784 #endif /* NO_SSH_LASTLOG */
785 
786 	do_motd();
787 }
788 
789 /*
790  * Display the message of the day.
791  */
792 void
793 do_motd(void)
794 {
795 	FILE *f;
796 	char buf[256];
797 #ifdef HAVE_LOGIN_CAP
798 	const char *fname;
799 #endif
800 
801 #ifdef HAVE_LOGIN_CAP
802 	fname = login_getcapstr(lc, "copyright", NULL, NULL);
803 	if (fname != NULL && (f = fopen(fname, "r")) != NULL) {
804 		while (fgets(buf, sizeof(buf), f) != NULL)
805 			fputs(buf, stdout);
806 			fclose(f);
807 	} else
808 #endif /* HAVE_LOGIN_CAP */
809 		(void)printf("%s\n\t%s %s\n",
810 	"Copyright (c) 1980, 1983, 1986, 1988, 1990, 1991, 1993, 1994",
811 	"The Regents of the University of California. ",
812 	"All rights reserved.");
813 
814 	(void)printf("\n");
815 
816 	if (options.print_motd) {
817 #ifdef HAVE_LOGIN_CAP
818 		f = fopen(login_getcapstr(lc, "welcome", "/etc/motd",
819 		    "/etc/motd"), "r");
820 #else
821 		f = fopen("/etc/motd", "r");
822 #endif
823 		if (f) {
824 			while (fgets(buf, sizeof(buf), f))
825 				fputs(buf, stdout);
826 			fclose(f);
827 		}
828 	}
829 }
830 
831 
832 /*
833  * Check for quiet login, either .hushlogin or command given.
834  */
835 int
836 check_quietlogin(Session *s, const char *command)
837 {
838 	char buf[256];
839 	struct passwd *pw = s->pw;
840 	struct stat st;
841 
842 	/* Return 1 if .hushlogin exists or a command given. */
843 	if (command != NULL)
844 		return 1;
845 	snprintf(buf, sizeof(buf), "%.200s/.hushlogin", pw->pw_dir);
846 #ifdef HAVE_LOGIN_CAP
847 	if (login_getcapbool(lc, "hushlogin", 0) || stat(buf, &st) >= 0)
848 		return 1;
849 #else
850 	if (stat(buf, &st) >= 0)
851 		return 1;
852 #endif
853 	return 0;
854 }
855 
856 /*
857  * Sets the value of the given variable in the environment.  If the variable
858  * already exists, its value is overriden.
859  */
860 static void
861 child_set_env(char ***envp, u_int *envsizep, const char *name,
862 	const char *value)
863 {
864 	u_int i, namelen;
865 	char **env;
866 
867 	/*
868 	 * Find the slot where the value should be stored.  If the variable
869 	 * already exists, we reuse the slot; otherwise we append a new slot
870 	 * at the end of the array, expanding if necessary.
871 	 */
872 	env = *envp;
873 	namelen = strlen(name);
874 	for (i = 0; env[i]; i++)
875 		if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=')
876 			break;
877 	if (env[i]) {
878 		/* Reuse the slot. */
879 		xfree(env[i]);
880 	} else {
881 		/* New variable.  Expand if necessary. */
882 		if (i >= (*envsizep) - 1) {
883 			if (*envsizep >= 1000)
884 				fatal("child_set_env: too many env vars,"
885 				    " skipping: %.100s", name);
886 			(*envsizep) += 50;
887 			env = (*envp) = xrealloc(env, (*envsizep) * sizeof(char *));
888 		}
889 		/* Need to set the NULL pointer at end of array beyond the new slot. */
890 		env[i + 1] = NULL;
891 	}
892 
893 	/* Allocate space and format the variable in the appropriate slot. */
894 	env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1);
895 	snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value);
896 }
897 
898 /*
899  * Reads environment variables from the given file and adds/overrides them
900  * into the environment.  If the file does not exist, this does nothing.
901  * Otherwise, it must consist of empty lines, comments (line starts with '#')
902  * and assignments of the form name=value.  No other forms are allowed.
903  */
904 static void
905 read_environment_file(char ***env, u_int *envsize,
906 	const char *filename)
907 {
908 	FILE *f;
909 	char buf[4096];
910 	char *cp, *value;
911 	u_int lineno = 0;
912 
913 	f = fopen(filename, "r");
914 	if (!f)
915 		return;
916 
917 	while (fgets(buf, sizeof(buf), f)) {
918 		if (++lineno > 1000)
919 			fatal("Too many lines in environment file %s", filename);
920 		for (cp = buf; *cp == ' ' || *cp == '\t'; cp++)
921 			;
922 		if (!*cp || *cp == '#' || *cp == '\n')
923 			continue;
924 		if (strchr(cp, '\n'))
925 			*strchr(cp, '\n') = '\0';
926 		value = strchr(cp, '=');
927 		if (value == NULL) {
928 			fprintf(stderr, "Bad line %u in %.100s\n", lineno,
929 			    filename);
930 			continue;
931 		}
932 		/*
933 		 * Replace the equals sign by nul, and advance value to
934 		 * the value string.
935 		 */
936 		*value = '\0';
937 		value++;
938 		child_set_env(env, envsize, cp, value);
939 	}
940 	fclose(f);
941 }
942 
943 void copy_environment(char **source, char ***env, u_int *envsize)
944 {
945 	char *var_name, *var_val;
946 	int i;
947 
948 	if (source == NULL)
949 		return;
950 
951 	for(i = 0; source[i] != NULL; i++) {
952 		var_name = xstrdup(source[i]);
953 		if ((var_val = strstr(var_name, "=")) == NULL) {
954 			xfree(var_name);
955 			continue;
956 		}
957 		*var_val++ = '\0';
958 
959 		debug3("Copy environment: %s=%s", var_name, var_val);
960 		child_set_env(env, envsize, var_name, var_val);
961 
962 		xfree(var_name);
963 	}
964 }
965 
966 static char **
967 do_setup_env(Session *s, const char *shell)
968 {
969 	char buf[256];
970 	u_int i, envsize;
971 	char **env;
972 #ifdef HAVE_LOGIN_CAP
973 	extern char **environ;
974 	char **senv, **var;
975 #endif
976 	struct passwd *pw = s->pw;
977 
978 	/* Initialize the environment. */
979 	envsize = 100;
980 	env = xmalloc(envsize * sizeof(char *));
981 	env[0] = NULL;
982 
983 #ifdef HAVE_CYGWIN
984 	/*
985 	 * The Windows environment contains some setting which are
986 	 * important for a running system. They must not be dropped.
987 	 */
988 	copy_environment(environ, &env, &envsize);
989 #endif
990 
991 	if (getenv("TZ"))
992 		child_set_env(&env, &envsize, "TZ", getenv("TZ"));
993 	if (!options.use_login) {
994 		/* Set basic environment. */
995 		child_set_env(&env, &envsize, "USER", pw->pw_name);
996 		child_set_env(&env, &envsize, "LOGNAME", pw->pw_name);
997 		child_set_env(&env, &envsize, "HOME", pw->pw_dir);
998 		snprintf(buf, sizeof buf, "%.200s/%.50s",
999 			 _PATH_MAILDIR, pw->pw_name);
1000 		child_set_env(&env, &envsize, "MAIL", buf);
1001 #ifdef HAVE_LOGIN_CAP
1002 		child_set_env(&env, &envsize, "PATH", _PATH_STDPATH);
1003 		child_set_env(&env, &envsize, "TERM", "su");
1004 		senv = environ;
1005 		environ = xmalloc(sizeof(char *));
1006 		*environ = NULL;
1007 		(void) setusercontext(lc, pw, pw->pw_uid,
1008 		    LOGIN_SETENV|LOGIN_SETPATH);
1009 		copy_environment(environ, &env, &envsize);
1010 		for (var = environ; *var != NULL; ++var)
1011 			xfree(*var);
1012 		xfree(environ);
1013 		environ = senv;
1014 #else /* HAVE_LOGIN_CAP */
1015 # ifndef HAVE_CYGWIN
1016 		/*
1017 		 * There's no standard path on Windows. The path contains
1018 		 * important components pointing to the system directories,
1019 		 * needed for loading shared libraries. So the path better
1020 		 * remains intact here.
1021 		 */
1022 #  ifdef SUPERUSER_PATH
1023 		child_set_env(&env, &envsize, "PATH",
1024 		    s->pw->pw_uid == 0 ? SUPERUSER_PATH : _PATH_STDPATH);
1025 #  else
1026 		child_set_env(&env, &envsize, "PATH", _PATH_STDPATH);
1027 #  endif /* SUPERUSER_PATH */
1028 # endif /* HAVE_CYGWIN */
1029 #endif /* HAVE_LOGIN_CAP */
1030 
1031 		/* Normal systems set SHELL by default. */
1032 		child_set_env(&env, &envsize, "SHELL", shell);
1033 	}
1034 
1035 	/* Set custom environment options from RSA authentication. */
1036 	if (!options.use_login) {
1037 		while (custom_environment) {
1038 			struct envstring *ce = custom_environment;
1039 			char *str = ce->s;
1040 
1041 			for (i = 0; str[i] != '=' && str[i]; i++)
1042 				;
1043 			if (str[i] == '=') {
1044 				str[i] = 0;
1045 				child_set_env(&env, &envsize, str, str + i + 1);
1046 			}
1047 			custom_environment = ce->next;
1048 			xfree(ce->s);
1049 			xfree(ce);
1050 		}
1051 	}
1052 
1053 	/* SSH_CLIENT deprecated */
1054 	snprintf(buf, sizeof buf, "%.50s %d %d",
1055 	    get_remote_ipaddr(), get_remote_port(), get_local_port());
1056 	child_set_env(&env, &envsize, "SSH_CLIENT", buf);
1057 
1058 	snprintf(buf, sizeof buf, "%.50s %d %.50s %d",
1059 	    get_remote_ipaddr(), get_remote_port(),
1060 	    get_local_ipaddr(packet_get_connection_in()), get_local_port());
1061 	child_set_env(&env, &envsize, "SSH_CONNECTION", buf);
1062 
1063 	if (s->ttyfd != -1)
1064 		child_set_env(&env, &envsize, "SSH_TTY", s->tty);
1065 	if (s->term)
1066 		child_set_env(&env, &envsize, "TERM", s->term);
1067 	if (s->display)
1068 		child_set_env(&env, &envsize, "DISPLAY", s->display);
1069 	if (original_command)
1070 		child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND",
1071 		    original_command);
1072 
1073 #ifdef _UNICOS
1074 	if (cray_tmpdir[0] != '\0')
1075 		child_set_env(&env, &envsize, "TMPDIR", cray_tmpdir);
1076 #endif /* _UNICOS */
1077 
1078 #ifdef _AIX
1079 	{
1080 		char *cp;
1081 
1082 		if ((cp = getenv("AUTHSTATE")) != NULL)
1083 			child_set_env(&env, &envsize, "AUTHSTATE", cp);
1084 		if ((cp = getenv("KRB5CCNAME")) != NULL)
1085 			child_set_env(&env, &envsize, "KRB5CCNAME", cp);
1086 		read_environment_file(&env, &envsize, "/etc/environment");
1087 	}
1088 #endif
1089 #ifdef KRB4
1090 	if (s->authctxt->krb4_ticket_file)
1091 		child_set_env(&env, &envsize, "KRBTKFILE",
1092 		    s->authctxt->krb4_ticket_file);
1093 #endif
1094 #ifdef KRB5
1095 	if (s->authctxt->krb5_ticket_file)
1096 		child_set_env(&env, &envsize, "KRB5CCNAME",
1097 		    s->authctxt->krb5_ticket_file);
1098 #endif
1099 #ifdef USE_PAM
1100 	/*
1101 	 * Pull in any environment variables that may have
1102 	 * been set by PAM.
1103 	 */
1104 	{
1105 		char **p;
1106 
1107 		p = fetch_pam_environment();
1108 		copy_environment(p, &env, &envsize);
1109 		free_pam_environment(p);
1110 	}
1111 #endif /* USE_PAM */
1112 
1113 	if (auth_sock_name != NULL)
1114 		child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME,
1115 		    auth_sock_name);
1116 
1117 	/* read $HOME/.ssh/environment. */
1118 	if (options.permit_user_env && !options.use_login) {
1119 		snprintf(buf, sizeof buf, "%.200s/.ssh/environment",
1120 		    strcmp(pw->pw_dir, "/") ? pw->pw_dir : "");
1121 		read_environment_file(&env, &envsize, buf);
1122 	}
1123 	if (debug_flag) {
1124 		/* dump the environment */
1125 		fprintf(stderr, "Environment:\n");
1126 		for (i = 0; env[i]; i++)
1127 			fprintf(stderr, "  %.200s\n", env[i]);
1128 	}
1129 	return env;
1130 }
1131 
1132 /*
1133  * Run $HOME/.ssh/rc, /etc/ssh/sshrc, or xauth (whichever is found
1134  * first in this order).
1135  */
1136 static void
1137 do_rc_files(Session *s, const char *shell)
1138 {
1139 	FILE *f = NULL;
1140 	char cmd[1024];
1141 	int do_xauth;
1142 	struct stat st;
1143 
1144 	do_xauth =
1145 	    s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL;
1146 
1147 	/* ignore _PATH_SSH_USER_RC for subsystems */
1148 	if (!s->is_subsystem && (stat(_PATH_SSH_USER_RC, &st) >= 0)) {
1149 		snprintf(cmd, sizeof cmd, "%s -c '%s %s'",
1150 		    shell, _PATH_BSHELL, _PATH_SSH_USER_RC);
1151 		if (debug_flag)
1152 			fprintf(stderr, "Running %s\n", cmd);
1153 		f = popen(cmd, "w");
1154 		if (f) {
1155 			if (do_xauth)
1156 				fprintf(f, "%s %s\n", s->auth_proto,
1157 				    s->auth_data);
1158 			pclose(f);
1159 		} else
1160 			fprintf(stderr, "Could not run %s\n",
1161 			    _PATH_SSH_USER_RC);
1162 	} else if (stat(_PATH_SSH_SYSTEM_RC, &st) >= 0) {
1163 		if (debug_flag)
1164 			fprintf(stderr, "Running %s %s\n", _PATH_BSHELL,
1165 			    _PATH_SSH_SYSTEM_RC);
1166 		f = popen(_PATH_BSHELL " " _PATH_SSH_SYSTEM_RC, "w");
1167 		if (f) {
1168 			if (do_xauth)
1169 				fprintf(f, "%s %s\n", s->auth_proto,
1170 				    s->auth_data);
1171 			pclose(f);
1172 		} else
1173 			fprintf(stderr, "Could not run %s\n",
1174 			    _PATH_SSH_SYSTEM_RC);
1175 	} else if (do_xauth && options.xauth_location != NULL) {
1176 		/* Add authority data to .Xauthority if appropriate. */
1177 		if (debug_flag) {
1178 			fprintf(stderr,
1179 			    "Running %.500s add "
1180 			    "%.100s %.100s %.100s\n",
1181 			    options.xauth_location, s->auth_display,
1182 			    s->auth_proto, s->auth_data);
1183 		}
1184 		snprintf(cmd, sizeof cmd, "%s -q -",
1185 		    options.xauth_location);
1186 		f = popen(cmd, "w");
1187 		if (f) {
1188 			fprintf(f, "add %s %s %s\n",
1189 			    s->auth_display, s->auth_proto,
1190 			    s->auth_data);
1191 			pclose(f);
1192 		} else {
1193 			fprintf(stderr, "Could not run %s\n",
1194 			    cmd);
1195 		}
1196 	}
1197 }
1198 
1199 static void
1200 do_nologin(struct passwd *pw)
1201 {
1202 	FILE *f = NULL;
1203 	char buf[1024];
1204 
1205 #ifdef HAVE_LOGIN_CAP
1206 	if (!login_getcapbool(lc, "ignorenologin", 0) && pw->pw_uid)
1207 		f = fopen(login_getcapstr(lc, "nologin", _PATH_NOLOGIN,
1208 		    _PATH_NOLOGIN), "r");
1209 #else
1210 	if (pw->pw_uid)
1211 		f = fopen(_PATH_NOLOGIN, "r");
1212 #endif
1213 	if (f) {
1214 		/* /etc/nologin exists.  Print its contents and exit. */
1215 		log("User %.100s not allowed because %s exists",
1216 		    pw->pw_name, _PATH_NOLOGIN);
1217 		while (fgets(buf, sizeof(buf), f))
1218 			fputs(buf, stderr);
1219 		fclose(f);
1220 		exit(254);
1221 	}
1222 }
1223 
1224 /* Set login name, uid, gid, and groups. */
1225 void
1226 do_setusercontext(struct passwd *pw)
1227 {
1228 #ifdef HAVE_CYGWIN
1229 	if (is_winnt) {
1230 #else /* HAVE_CYGWIN */
1231 	if (getuid() == 0 || geteuid() == 0) {
1232 #endif /* HAVE_CYGWIN */
1233 #ifdef HAVE_SETPCRED
1234 		setpcred(pw->pw_name);
1235 #endif /* HAVE_SETPCRED */
1236 #ifdef HAVE_LOGIN_CAP
1237 # ifdef __bsdi__
1238 		setpgid(0, 0);
1239 # endif
1240 		if (setusercontext(lc, pw, pw->pw_uid,
1241 		    (LOGIN_SETALL & ~(LOGIN_SETENV|LOGIN_SETPATH))) < 0) {
1242 			perror("unable to set user context");
1243 			exit(1);
1244 		}
1245 #else
1246 # if defined(HAVE_GETLUID) && defined(HAVE_SETLUID)
1247 		/* Sets login uid for accounting */
1248 		if (getluid() == -1 && setluid(pw->pw_uid) == -1)
1249 			error("setluid: %s", strerror(errno));
1250 # endif /* defined(HAVE_GETLUID) && defined(HAVE_SETLUID) */
1251 
1252 		if (setlogin(pw->pw_name) < 0)
1253 			error("setlogin failed: %s", strerror(errno));
1254 		if (setgid(pw->pw_gid) < 0) {
1255 			perror("setgid");
1256 			exit(1);
1257 		}
1258 		/* Initialize the group list. */
1259 		if (initgroups(pw->pw_name, pw->pw_gid) < 0) {
1260 			perror("initgroups");
1261 			exit(1);
1262 		}
1263 		endgrent();
1264 # ifdef USE_PAM
1265 		/*
1266 		 * PAM credentials may take the form of supplementary groups.
1267 		 * These will have been wiped by the above initgroups() call.
1268 		 * Reestablish them here.
1269 		 */
1270 		do_pam_setcred(0);
1271 # endif /* USE_PAM */
1272 # if defined(WITH_IRIX_PROJECT) || defined(WITH_IRIX_JOBS) || defined(WITH_IRIX_ARRAY)
1273 		irix_setusercontext(pw);
1274 #  endif /* defined(WITH_IRIX_PROJECT) || defined(WITH_IRIX_JOBS) || defined(WITH_IRIX_ARRAY) */
1275 # ifdef _AIX
1276 		aix_usrinfo(pw);
1277 # endif /* _AIX */
1278 		/* Permanently switch to the desired uid. */
1279 		permanently_set_uid(pw);
1280 #endif
1281 	}
1282 	if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid)
1283 		fatal("Failed to set uids to %u.", (u_int) pw->pw_uid);
1284 }
1285 
1286 static void
1287 launch_login(struct passwd *pw, const char *hostname)
1288 {
1289 	/* Launch login(1). */
1290 
1291 	execl(LOGIN_PROGRAM, "login", "-h", hostname,
1292 #ifdef xxxLOGIN_NEEDS_TERM
1293 		    (s->term ? s->term : "unknown"),
1294 #endif /* LOGIN_NEEDS_TERM */
1295 #ifdef LOGIN_NO_ENDOPT
1296 	    "-p", "-f", pw->pw_name, (char *)NULL);
1297 #else
1298 	    "-p", "-f", "--", pw->pw_name, (char *)NULL);
1299 #endif
1300 
1301 	/* Login couldn't be executed, die. */
1302 
1303 	perror("login");
1304 	exit(1);
1305 }
1306 
1307 /*
1308  * Performs common processing for the child, such as setting up the
1309  * environment, closing extra file descriptors, setting the user and group
1310  * ids, and executing the command or shell.
1311  */
1312 void
1313 do_child(Session *s, const char *command)
1314 {
1315 	extern char **environ;
1316 	char **env;
1317 	char *argv[10];
1318 	const char *shell, *shell0, *hostname = NULL;
1319 	struct passwd *pw = s->pw;
1320 	u_int i;
1321 #ifdef HAVE_LOGIN_CAP
1322 	int lc_requirehome;
1323 #endif
1324 
1325 	/* remove hostkey from the child's memory */
1326 	destroy_sensitive_data();
1327 
1328 	/* login(1) is only called if we execute the login shell */
1329 	if (options.use_login && command != NULL)
1330 		options.use_login = 0;
1331 
1332 #ifdef _UNICOS
1333 	cray_setup(pw->pw_uid, pw->pw_name, command);
1334 #endif /* _UNICOS */
1335 
1336 	/*
1337 	 * Login(1) does this as well, and it needs uid 0 for the "-h"
1338 	 * switch, so we let login(1) to this for us.
1339 	 */
1340 	if (!options.use_login) {
1341 #ifdef HAVE_OSF_SIA
1342 		session_setup_sia(pw->pw_name, s->ttyfd == -1 ? NULL : s->tty);
1343 		if (!check_quietlogin(s, command))
1344 			do_motd();
1345 #else /* HAVE_OSF_SIA */
1346 		do_nologin(pw);
1347 		do_setusercontext(pw);
1348 #endif /* HAVE_OSF_SIA */
1349 	}
1350 
1351 	/*
1352 	 * Get the shell from the password data.  An empty shell field is
1353 	 * legal, and means /bin/sh.
1354 	 */
1355 	shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;
1356 #ifdef HAVE_LOGIN_CAP
1357 	shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell);
1358 #endif
1359 
1360 	env = do_setup_env(s, shell);
1361 
1362 	/* we have to stash the hostname before we close our socket. */
1363 	if (options.use_login)
1364 		hostname = get_remote_name_or_ip(utmp_len,
1365 		    options.verify_reverse_mapping);
1366 	/*
1367 	 * Close the connection descriptors; note that this is the child, and
1368 	 * the server will still have the socket open, and it is important
1369 	 * that we do not shutdown it.  Note that the descriptors cannot be
1370 	 * closed before building the environment, as we call
1371 	 * get_remote_ipaddr there.
1372 	 */
1373 	if (packet_get_connection_in() == packet_get_connection_out())
1374 		close(packet_get_connection_in());
1375 	else {
1376 		close(packet_get_connection_in());
1377 		close(packet_get_connection_out());
1378 	}
1379 	/*
1380 	 * Close all descriptors related to channels.  They will still remain
1381 	 * open in the parent.
1382 	 */
1383 	/* XXX better use close-on-exec? -markus */
1384 	channel_close_all();
1385 
1386 #ifdef HAVE_LOGIN_CAP
1387 	lc_requirehome = login_getcapbool(lc, "requirehome", 0);
1388 	login_close(lc);
1389 #endif
1390 	/*
1391 	 * Close any extra file descriptors.  Note that there may still be
1392 	 * descriptors left by system functions.  They will be closed later.
1393 	 */
1394 	endpwent();
1395 
1396 	/*
1397 	 * Close any extra open file descriptors so that we don\'t have them
1398 	 * hanging around in clients.  Note that we want to do this after
1399 	 * initgroups, because at least on Solaris 2.3 it leaves file
1400 	 * descriptors open.
1401 	 */
1402 	for (i = 3; i < 64; i++)
1403 		close(i);
1404 
1405 	/*
1406 	 * Must take new environment into use so that .ssh/rc,
1407 	 * /etc/ssh/sshrc and xauth are run in the proper environment.
1408 	 */
1409 	environ = env;
1410 
1411 #ifdef AFS
1412 	/* Try to get AFS tokens for the local cell. */
1413 	if (k_hasafs()) {
1414 		char cell[64];
1415 
1416 		if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0)
1417 			krb_afslog(cell, 0);
1418 
1419 		krb_afslog(0, 0);
1420 	}
1421 #endif /* AFS */
1422 
1423 	/* Change current directory to the user\'s home directory. */
1424 	if (chdir(pw->pw_dir) < 0) {
1425 		fprintf(stderr, "Could not chdir to home directory %s: %s\n",
1426 		    pw->pw_dir, strerror(errno));
1427 #ifdef HAVE_LOGIN_CAP
1428 		if (lc_requirehome)
1429 			exit(1);
1430 #endif
1431 	}
1432 
1433 	if (!options.use_login)
1434 		do_rc_files(s, shell);
1435 
1436 	/* restore SIGPIPE for child */
1437 	signal(SIGPIPE,  SIG_DFL);
1438 
1439 	if (options.use_login) {
1440 		launch_login(pw, hostname);
1441 		/* NEVERREACHED */
1442 	}
1443 
1444 	/* Get the last component of the shell name. */
1445 	if ((shell0 = strrchr(shell, '/')) != NULL)
1446 		shell0++;
1447 	else
1448 		shell0 = shell;
1449 
1450 	/*
1451 	 * If we have no command, execute the shell.  In this case, the shell
1452 	 * name to be passed in argv[0] is preceded by '-' to indicate that
1453 	 * this is a login shell.
1454 	 */
1455 	if (!command) {
1456 		char argv0[256];
1457 
1458 		/* Start the shell.  Set initial character to '-'. */
1459 		argv0[0] = '-';
1460 
1461 		if (strlcpy(argv0 + 1, shell0, sizeof(argv0) - 1)
1462 		    >= sizeof(argv0) - 1) {
1463 			errno = EINVAL;
1464 			perror(shell);
1465 			exit(1);
1466 		}
1467 
1468 		/* Execute the shell. */
1469 		argv[0] = argv0;
1470 		argv[1] = NULL;
1471 		execve(shell, argv, env);
1472 
1473 		/* Executing the shell failed. */
1474 		perror(shell);
1475 		exit(1);
1476 	}
1477 	/*
1478 	 * Execute the command using the user's shell.  This uses the -c
1479 	 * option to execute the command.
1480 	 */
1481 	argv[0] = (char *) shell0;
1482 	argv[1] = "-c";
1483 	argv[2] = (char *) command;
1484 	argv[3] = NULL;
1485 	execve(shell, argv, env);
1486 	perror(shell);
1487 	exit(1);
1488 }
1489 
1490 Session *
1491 session_new(void)
1492 {
1493 	int i;
1494 	static int did_init = 0;
1495 	if (!did_init) {
1496 		debug("session_new: init");
1497 		for (i = 0; i < MAX_SESSIONS; i++) {
1498 			sessions[i].used = 0;
1499 		}
1500 		did_init = 1;
1501 	}
1502 	for (i = 0; i < MAX_SESSIONS; i++) {
1503 		Session *s = &sessions[i];
1504 		if (! s->used) {
1505 			memset(s, 0, sizeof(*s));
1506 			s->chanid = -1;
1507 			s->ptyfd = -1;
1508 			s->ttyfd = -1;
1509 			s->used = 1;
1510 			s->self = i;
1511 			debug("session_new: session %d", i);
1512 			return s;
1513 		}
1514 	}
1515 	return NULL;
1516 }
1517 
1518 static void
1519 session_dump(void)
1520 {
1521 	int i;
1522 	for (i = 0; i < MAX_SESSIONS; i++) {
1523 		Session *s = &sessions[i];
1524 		debug("dump: used %d session %d %p channel %d pid %ld",
1525 		    s->used,
1526 		    s->self,
1527 		    s,
1528 		    s->chanid,
1529 		    (long)s->pid);
1530 	}
1531 }
1532 
1533 int
1534 session_open(Authctxt *authctxt, int chanid)
1535 {
1536 	Session *s = session_new();
1537 	debug("session_open: channel %d", chanid);
1538 	if (s == NULL) {
1539 		error("no more sessions");
1540 		return 0;
1541 	}
1542 	s->authctxt = authctxt;
1543 	s->pw = authctxt->pw;
1544 	if (s->pw == NULL)
1545 		fatal("no user for session %d", s->self);
1546 	debug("session_open: session %d: link with channel %d", s->self, chanid);
1547 	s->chanid = chanid;
1548 	return 1;
1549 }
1550 
1551 Session *
1552 session_by_tty(char *tty)
1553 {
1554 	int i;
1555 	for (i = 0; i < MAX_SESSIONS; i++) {
1556 		Session *s = &sessions[i];
1557 		if (s->used && s->ttyfd != -1 && strcmp(s->tty, tty) == 0) {
1558 			debug("session_by_tty: session %d tty %s", i, tty);
1559 			return s;
1560 		}
1561 	}
1562 	debug("session_by_tty: unknown tty %.100s", tty);
1563 	session_dump();
1564 	return NULL;
1565 }
1566 
1567 static Session *
1568 session_by_channel(int id)
1569 {
1570 	int i;
1571 	for (i = 0; i < MAX_SESSIONS; i++) {
1572 		Session *s = &sessions[i];
1573 		if (s->used && s->chanid == id) {
1574 			debug("session_by_channel: session %d channel %d", i, id);
1575 			return s;
1576 		}
1577 	}
1578 	debug("session_by_channel: unknown channel %d", id);
1579 	session_dump();
1580 	return NULL;
1581 }
1582 
1583 static Session *
1584 session_by_pid(pid_t pid)
1585 {
1586 	int i;
1587 	debug("session_by_pid: pid %ld", (long)pid);
1588 	for (i = 0; i < MAX_SESSIONS; i++) {
1589 		Session *s = &sessions[i];
1590 		if (s->used && s->pid == pid)
1591 			return s;
1592 	}
1593 	error("session_by_pid: unknown pid %ld", (long)pid);
1594 	session_dump();
1595 	return NULL;
1596 }
1597 
1598 static int
1599 session_window_change_req(Session *s)
1600 {
1601 	s->col = packet_get_int();
1602 	s->row = packet_get_int();
1603 	s->xpixel = packet_get_int();
1604 	s->ypixel = packet_get_int();
1605 	packet_check_eom();
1606 	pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel);
1607 	return 1;
1608 }
1609 
1610 static int
1611 session_pty_req(Session *s)
1612 {
1613 	u_int len;
1614 	int n_bytes;
1615 
1616 	if (no_pty_flag) {
1617 		debug("Allocating a pty not permitted for this authentication.");
1618 		return 0;
1619 	}
1620 	if (s->ttyfd != -1) {
1621 		packet_disconnect("Protocol error: you already have a pty.");
1622 		return 0;
1623 	}
1624 	/* Get the time and hostname when the user last logged in. */
1625 	if (options.print_lastlog) {
1626 		s->hostname[0] = '\0';
1627 		s->last_login_time = get_last_login_time(s->pw->pw_uid,
1628 		    s->pw->pw_name, s->hostname, sizeof(s->hostname));
1629 	}
1630 
1631 	s->term = packet_get_string(&len);
1632 
1633 	if (compat20) {
1634 		s->col = packet_get_int();
1635 		s->row = packet_get_int();
1636 	} else {
1637 		s->row = packet_get_int();
1638 		s->col = packet_get_int();
1639 	}
1640 	s->xpixel = packet_get_int();
1641 	s->ypixel = packet_get_int();
1642 
1643 	if (strcmp(s->term, "") == 0) {
1644 		xfree(s->term);
1645 		s->term = NULL;
1646 	}
1647 
1648 	/* Allocate a pty and open it. */
1649 	debug("Allocating pty.");
1650 	if (!PRIVSEP(pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty)))) {
1651 		if (s->term)
1652 			xfree(s->term);
1653 		s->term = NULL;
1654 		s->ptyfd = -1;
1655 		s->ttyfd = -1;
1656 		error("session_pty_req: session %d alloc failed", s->self);
1657 		return 0;
1658 	}
1659 	debug("session_pty_req: session %d alloc %s", s->self, s->tty);
1660 
1661 	/* for SSH1 the tty modes length is not given */
1662 	if (!compat20)
1663 		n_bytes = packet_remaining();
1664 	tty_parse_modes(s->ttyfd, &n_bytes);
1665 
1666 	/*
1667 	 * Add a cleanup function to clear the utmp entry and record logout
1668 	 * time in case we call fatal() (e.g., the connection gets closed).
1669 	 */
1670 	fatal_add_cleanup(session_pty_cleanup, (void *)s);
1671 	if (!use_privsep)
1672 		pty_setowner(s->pw, s->tty);
1673 
1674 	/* Set window size from the packet. */
1675 	pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel);
1676 
1677 	packet_check_eom();
1678 	session_proctitle(s);
1679 	return 1;
1680 }
1681 
1682 static int
1683 session_subsystem_req(Session *s)
1684 {
1685 	struct stat st;
1686 	u_int len;
1687 	int success = 0;
1688 	char *cmd, *subsys = packet_get_string(&len);
1689 	int i;
1690 
1691 	packet_check_eom();
1692 	log("subsystem request for %.100s", subsys);
1693 
1694 	for (i = 0; i < options.num_subsystems; i++) {
1695 		if (strcmp(subsys, options.subsystem_name[i]) == 0) {
1696 			cmd = options.subsystem_command[i];
1697 			if (stat(cmd, &st) < 0) {
1698 				error("subsystem: cannot stat %s: %s", cmd,
1699 				    strerror(errno));
1700 				break;
1701 			}
1702 			debug("subsystem: exec() %s", cmd);
1703 			s->is_subsystem = 1;
1704 			do_exec(s, cmd);
1705 			success = 1;
1706 			break;
1707 		}
1708 	}
1709 
1710 	if (!success)
1711 		log("subsystem request for %.100s failed, subsystem not found",
1712 		    subsys);
1713 
1714 	xfree(subsys);
1715 	return success;
1716 }
1717 
1718 static int
1719 session_x11_req(Session *s)
1720 {
1721 	int success;
1722 
1723 	s->single_connection = packet_get_char();
1724 	s->auth_proto = packet_get_string(NULL);
1725 	s->auth_data = packet_get_string(NULL);
1726 	s->screen = packet_get_int();
1727 	packet_check_eom();
1728 
1729 	success = session_setup_x11fwd(s);
1730 	if (!success) {
1731 		xfree(s->auth_proto);
1732 		xfree(s->auth_data);
1733 		s->auth_proto = NULL;
1734 		s->auth_data = NULL;
1735 	}
1736 	return success;
1737 }
1738 
1739 static int
1740 session_shell_req(Session *s)
1741 {
1742 	packet_check_eom();
1743 	do_exec(s, NULL);
1744 	return 1;
1745 }
1746 
1747 static int
1748 session_exec_req(Session *s)
1749 {
1750 	u_int len;
1751 	char *command = packet_get_string(&len);
1752 	packet_check_eom();
1753 	do_exec(s, command);
1754 	xfree(command);
1755 	return 1;
1756 }
1757 
1758 static int
1759 session_auth_agent_req(Session *s)
1760 {
1761 	static int called = 0;
1762 	packet_check_eom();
1763 	if (no_agent_forwarding_flag) {
1764 		debug("session_auth_agent_req: no_agent_forwarding_flag");
1765 		return 0;
1766 	}
1767 	if (called) {
1768 		return 0;
1769 	} else {
1770 		called = 1;
1771 		return auth_input_request_forwarding(s->pw);
1772 	}
1773 }
1774 
1775 int
1776 session_input_channel_req(Channel *c, const char *rtype)
1777 {
1778 	int success = 0;
1779 	Session *s;
1780 
1781 	if ((s = session_by_channel(c->self)) == NULL) {
1782 		log("session_input_channel_req: no session %d req %.100s",
1783 		    c->self, rtype);
1784 		return 0;
1785 	}
1786 	debug("session_input_channel_req: session %d req %s", s->self, rtype);
1787 
1788 	/*
1789 	 * a session is in LARVAL state until a shell, a command
1790 	 * or a subsystem is executed
1791 	 */
1792 	if (c->type == SSH_CHANNEL_LARVAL) {
1793 		if (strcmp(rtype, "shell") == 0) {
1794 			success = session_shell_req(s);
1795 		} else if (strcmp(rtype, "exec") == 0) {
1796 			success = session_exec_req(s);
1797 		} else if (strcmp(rtype, "pty-req") == 0) {
1798 			success =  session_pty_req(s);
1799 		} else if (strcmp(rtype, "x11-req") == 0) {
1800 			success = session_x11_req(s);
1801 		} else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) {
1802 			success = session_auth_agent_req(s);
1803 		} else if (strcmp(rtype, "subsystem") == 0) {
1804 			success = session_subsystem_req(s);
1805 		}
1806 	}
1807 	if (strcmp(rtype, "window-change") == 0) {
1808 		success = session_window_change_req(s);
1809 	}
1810 	return success;
1811 }
1812 
1813 void
1814 session_set_fds(Session *s, int fdin, int fdout, int fderr)
1815 {
1816 	if (!compat20)
1817 		fatal("session_set_fds: called for proto != 2.0");
1818 	/*
1819 	 * now that have a child and a pipe to the child,
1820 	 * we can activate our channel and register the fd's
1821 	 */
1822 	if (s->chanid == -1)
1823 		fatal("no channel for session %d", s->self);
1824 	channel_set_fds(s->chanid,
1825 	    fdout, fdin, fderr,
1826 	    fderr == -1 ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ,
1827 	    1,
1828 	    CHAN_SES_WINDOW_DEFAULT);
1829 }
1830 
1831 /*
1832  * Function to perform pty cleanup. Also called if we get aborted abnormally
1833  * (e.g., due to a dropped connection).
1834  */
1835 void
1836 session_pty_cleanup2(void *session)
1837 {
1838 	Session *s = session;
1839 
1840 	if (s == NULL) {
1841 		error("session_pty_cleanup: no session");
1842 		return;
1843 	}
1844 	if (s->ttyfd == -1)
1845 		return;
1846 
1847 	debug("session_pty_cleanup: session %d release %s", s->self, s->tty);
1848 
1849 	/* Record that the user has logged out. */
1850 	if (s->pid != 0)
1851 		record_logout(s->pid, s->tty, s->pw->pw_name);
1852 
1853 	/* Release the pseudo-tty. */
1854 	if (getuid() == 0)
1855 		pty_release(s->tty);
1856 
1857 	/*
1858 	 * Close the server side of the socket pairs.  We must do this after
1859 	 * the pty cleanup, so that another process doesn't get this pty
1860 	 * while we're still cleaning up.
1861 	 */
1862 	if (close(s->ptymaster) < 0)
1863 		error("close(s->ptymaster/%d): %s", s->ptymaster, strerror(errno));
1864 
1865 	/* unlink pty from session */
1866 	s->ttyfd = -1;
1867 }
1868 
1869 void
1870 session_pty_cleanup(void *session)
1871 {
1872 	PRIVSEP(session_pty_cleanup2(session));
1873 }
1874 
1875 static char *
1876 sig2name(int sig)
1877 {
1878 #define SSH_SIG(x) if (sig == SIG ## x) return #x
1879 	SSH_SIG(ABRT);
1880 	SSH_SIG(ALRM);
1881 	SSH_SIG(FPE);
1882 	SSH_SIG(HUP);
1883 	SSH_SIG(ILL);
1884 	SSH_SIG(INT);
1885 	SSH_SIG(KILL);
1886 	SSH_SIG(PIPE);
1887 	SSH_SIG(QUIT);
1888 	SSH_SIG(SEGV);
1889 	SSH_SIG(TERM);
1890 	SSH_SIG(USR1);
1891 	SSH_SIG(USR2);
1892 #undef	SSH_SIG
1893 	return "SIG@openssh.com";
1894 }
1895 
1896 static void
1897 session_exit_message(Session *s, int status)
1898 {
1899 	Channel *c;
1900 
1901 	if ((c = channel_lookup(s->chanid)) == NULL)
1902 		fatal("session_exit_message: session %d: no channel %d",
1903 		    s->self, s->chanid);
1904 	debug("session_exit_message: session %d channel %d pid %ld",
1905 	    s->self, s->chanid, (long)s->pid);
1906 
1907 	if (WIFEXITED(status)) {
1908 		channel_request_start(s->chanid, "exit-status", 0);
1909 		packet_put_int(WEXITSTATUS(status));
1910 		packet_send();
1911 	} else if (WIFSIGNALED(status)) {
1912 		channel_request_start(s->chanid, "exit-signal", 0);
1913 		packet_put_cstring(sig2name(WTERMSIG(status)));
1914 #ifdef WCOREDUMP
1915 		packet_put_char(WCOREDUMP(status));
1916 #else /* WCOREDUMP */
1917 		packet_put_char(0);
1918 #endif /* WCOREDUMP */
1919 		packet_put_cstring("");
1920 		packet_put_cstring("");
1921 		packet_send();
1922 	} else {
1923 		/* Some weird exit cause.  Just exit. */
1924 		packet_disconnect("wait returned status %04x.", status);
1925 	}
1926 
1927 	/* disconnect channel */
1928 	debug("session_exit_message: release channel %d", s->chanid);
1929 	channel_cancel_cleanup(s->chanid);
1930 	/*
1931 	 * emulate a write failure with 'chan_write_failed', nobody will be
1932 	 * interested in data we write.
1933 	 * Note that we must not call 'chan_read_failed', since there could
1934 	 * be some more data waiting in the pipe.
1935 	 */
1936 	if (c->ostate != CHAN_OUTPUT_CLOSED)
1937 		chan_write_failed(c);
1938 	s->chanid = -1;
1939 }
1940 
1941 void
1942 session_close(Session *s)
1943 {
1944 	debug("session_close: session %d pid %ld", s->self, (long)s->pid);
1945 	if (s->ttyfd != -1) {
1946 		fatal_remove_cleanup(session_pty_cleanup, (void *)s);
1947 		session_pty_cleanup(s);
1948 	}
1949 	if (s->term)
1950 		xfree(s->term);
1951 	if (s->display)
1952 		xfree(s->display);
1953 	if (s->auth_display)
1954 		xfree(s->auth_display);
1955 	if (s->auth_data)
1956 		xfree(s->auth_data);
1957 	if (s->auth_proto)
1958 		xfree(s->auth_proto);
1959 	s->used = 0;
1960 	session_proctitle(s);
1961 }
1962 
1963 void
1964 session_close_by_pid(pid_t pid, int status)
1965 {
1966 	Session *s = session_by_pid(pid);
1967 	if (s == NULL) {
1968 		debug("session_close_by_pid: no session for pid %ld",
1969 		    (long)pid);
1970 		return;
1971 	}
1972 	if (s->chanid != -1)
1973 		session_exit_message(s, status);
1974 	session_close(s);
1975 }
1976 
1977 /*
1978  * this is called when a channel dies before
1979  * the session 'child' itself dies
1980  */
1981 void
1982 session_close_by_channel(int id, void *arg)
1983 {
1984 	Session *s = session_by_channel(id);
1985 	if (s == NULL) {
1986 		debug("session_close_by_channel: no session for id %d", id);
1987 		return;
1988 	}
1989 	debug("session_close_by_channel: channel %d child %ld",
1990 	    id, (long)s->pid);
1991 	if (s->pid != 0) {
1992 		debug("session_close_by_channel: channel %d: has child", id);
1993 		/*
1994 		 * delay detach of session, but release pty, since
1995 		 * the fd's to the child are already closed
1996 		 */
1997 		if (s->ttyfd != -1) {
1998 			fatal_remove_cleanup(session_pty_cleanup, (void *)s);
1999 			session_pty_cleanup(s);
2000 		}
2001 		return;
2002 	}
2003 	/* detach by removing callback */
2004 	channel_cancel_cleanup(s->chanid);
2005 	s->chanid = -1;
2006 	session_close(s);
2007 }
2008 
2009 void
2010 session_destroy_all(void (*closefunc)(Session *))
2011 {
2012 	int i;
2013 	for (i = 0; i < MAX_SESSIONS; i++) {
2014 		Session *s = &sessions[i];
2015 		if (s->used) {
2016 			if (closefunc != NULL)
2017 				closefunc(s);
2018 			else
2019 				session_close(s);
2020 		}
2021 	}
2022 }
2023 
2024 static char *
2025 session_tty_list(void)
2026 {
2027 	static char buf[1024];
2028 	int i;
2029 	buf[0] = '\0';
2030 	for (i = 0; i < MAX_SESSIONS; i++) {
2031 		Session *s = &sessions[i];
2032 		if (s->used && s->ttyfd != -1) {
2033 			if (buf[0] != '\0')
2034 				strlcat(buf, ",", sizeof buf);
2035 			strlcat(buf, strrchr(s->tty, '/') + 1, sizeof buf);
2036 		}
2037 	}
2038 	if (buf[0] == '\0')
2039 		strlcpy(buf, "notty", sizeof buf);
2040 	return buf;
2041 }
2042 
2043 void
2044 session_proctitle(Session *s)
2045 {
2046 	if (s->pw == NULL)
2047 		error("no user for session %d", s->self);
2048 	else
2049 		setproctitle("%s@%s", s->pw->pw_name, session_tty_list());
2050 }
2051 
2052 int
2053 session_setup_x11fwd(Session *s)
2054 {
2055 	struct stat st;
2056 	char display[512], auth_display[512];
2057 	char hostname[MAXHOSTNAMELEN];
2058 
2059 	if (no_x11_forwarding_flag) {
2060 		packet_send_debug("X11 forwarding disabled in user configuration file.");
2061 		return 0;
2062 	}
2063 	if (!options.x11_forwarding) {
2064 		debug("X11 forwarding disabled in server configuration file.");
2065 		return 0;
2066 	}
2067 	if (!options.xauth_location ||
2068 	    (stat(options.xauth_location, &st) == -1)) {
2069 		packet_send_debug("No xauth program; cannot forward with spoofing.");
2070 		return 0;
2071 	}
2072 	if (options.use_login) {
2073 		packet_send_debug("X11 forwarding disabled; "
2074 		    "not compatible with UseLogin=yes.");
2075 		return 0;
2076 	}
2077 	if (s->display != NULL) {
2078 		debug("X11 display already set.");
2079 		return 0;
2080 	}
2081 	if (x11_create_display_inet(options.x11_display_offset,
2082 	    options.x11_use_localhost, s->single_connection,
2083 	    &s->display_number) == -1) {
2084 		debug("x11_create_display_inet failed.");
2085 		return 0;
2086 	}
2087 
2088 	/* Set up a suitable value for the DISPLAY variable. */
2089 	if (gethostname(hostname, sizeof(hostname)) < 0)
2090 		fatal("gethostname: %.100s", strerror(errno));
2091 	/*
2092 	 * auth_display must be used as the displayname when the
2093 	 * authorization entry is added with xauth(1).  This will be
2094 	 * different than the DISPLAY string for localhost displays.
2095 	 */
2096 	if (options.x11_use_localhost) {
2097 		snprintf(display, sizeof display, "localhost:%u.%u",
2098 		    s->display_number, s->screen);
2099 		snprintf(auth_display, sizeof auth_display, "unix:%u.%u",
2100 		    s->display_number, s->screen);
2101 		s->display = xstrdup(display);
2102 		s->auth_display = xstrdup(auth_display);
2103 	} else {
2104 #ifdef IPADDR_IN_DISPLAY
2105 		struct hostent *he;
2106 		struct in_addr my_addr;
2107 
2108 		he = gethostbyname(hostname);
2109 		if (he == NULL) {
2110 			error("Can't get IP address for X11 DISPLAY.");
2111 			packet_send_debug("Can't get IP address for X11 DISPLAY.");
2112 			return 0;
2113 		}
2114 		memcpy(&my_addr, he->h_addr_list[0], sizeof(struct in_addr));
2115 		snprintf(display, sizeof display, "%.50s:%u.%u", inet_ntoa(my_addr),
2116 		    s->display_number, s->screen);
2117 #else
2118 		snprintf(display, sizeof display, "%.400s:%u.%u", hostname,
2119 		    s->display_number, s->screen);
2120 #endif
2121 		s->display = xstrdup(display);
2122 		s->auth_display = xstrdup(display);
2123 	}
2124 
2125 	return 1;
2126 }
2127 
2128 static void
2129 do_authenticated2(Authctxt *authctxt)
2130 {
2131 	server_loop2(authctxt);
2132 }
2133