session.c revision 99063
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"
36RCSID("$OpenBSD: session.c,v 1.142 2002/06/26 13:49:26 deraadt Exp $");
37RCSID("$FreeBSD: head/crypto/openssh/session.c 99063 2002-06-29 11:48:59Z des $");
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
70Session *session_new(void);
71void	session_set_fds(Session *, int, int, int);
72void	session_pty_cleanup(void *);
73void	session_proctitle(Session *);
74int	session_setup_x11fwd(Session *);
75void	do_exec_pty(Session *, const char *);
76void	do_exec_no_pty(Session *, const char *);
77void	do_exec(Session *, const char *);
78void	do_login(Session *, const char *);
79#ifdef LOGIN_NEEDS_UTMPX
80static void	do_pre_login(Session *s);
81#endif
82void	do_child(Session *, const char *);
83void	do_motd(void);
84int	check_quietlogin(Session *, const char *);
85
86static void do_authenticated1(Authctxt *);
87static void do_authenticated2(Authctxt *);
88
89static int session_pty_req(Session *);
90
91/* import */
92extern ServerOptions options;
93extern char *__progname;
94extern int log_stderr;
95extern int debug_flag;
96extern u_int utmp_len;
97extern int startup_pipe;
98extern void destroy_sensitive_data(void);
99
100/* original command from peer. */
101const char *original_command = NULL;
102
103/* data */
104#define MAX_SESSIONS 10
105Session	sessions[MAX_SESSIONS];
106
107#ifdef WITH_AIXAUTHENTICATE
108char *aixloginmsg;
109#endif /* WITH_AIXAUTHENTICATE */
110
111#ifdef HAVE_LOGIN_CAP
112login_cap_t *lc;
113#endif
114
115/* Name and directory of socket for authentication agent forwarding. */
116static char *auth_sock_name = NULL;
117static char *auth_sock_dir = NULL;
118
119/* removes the agent forwarding socket */
120
121static void
122auth_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
135static int
136auth_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
202void
203do_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#ifdef WITH_AIXAUTHENTICATE
215	/* We don't have a pty yet, so just label the line as "ssh" */
216	if (loginsuccess(authctxt->user,
217	    get_canonical_hostname(options.verify_reverse_mapping),
218	    "ssh", &aixloginmsg) < 0)
219		aixloginmsg = NULL;
220#endif /* WITH_AIXAUTHENTICATE */
221
222	/* setup the channel layer */
223	if (!no_port_forwarding_flag && options.allow_tcp_forwarding)
224		channel_permit_all_opens();
225
226	if (compat20)
227		do_authenticated2(authctxt);
228	else
229		do_authenticated1(authctxt);
230
231	/* remove agent socket */
232	if (auth_sock_name != NULL)
233		auth_sock_cleanup_proc(authctxt->pw);
234#ifdef KRB4
235	if (options.kerberos_ticket_cleanup)
236		krb4_cleanup_proc(authctxt);
237#endif
238#ifdef KRB5
239	if (options.kerberos_ticket_cleanup)
240		krb5_cleanup_proc(authctxt);
241#endif
242}
243
244/*
245 * Prepares for an interactive session.  This is called after the user has
246 * been successfully authenticated.  During this message exchange, pseudo
247 * terminals are allocated, X11, TCP/IP, and authentication agent forwardings
248 * are requested, etc.
249 */
250static void
251do_authenticated1(Authctxt *authctxt)
252{
253	Session *s;
254	char *command;
255	int success, type, screen_flag;
256	int enable_compression_after_reply = 0;
257	u_int proto_len, data_len, dlen, compression_level = 0;
258
259	s = session_new();
260	s->authctxt = authctxt;
261	s->pw = authctxt->pw;
262
263	/*
264	 * We stay in this loop until the client requests to execute a shell
265	 * or a command.
266	 */
267	for (;;) {
268		success = 0;
269
270		/* Get a packet from the client. */
271		type = packet_read();
272
273		/* Process the packet. */
274		switch (type) {
275		case SSH_CMSG_REQUEST_COMPRESSION:
276			compression_level = packet_get_int();
277			packet_check_eom();
278			if (compression_level < 1 || compression_level > 9) {
279				packet_send_debug("Received illegal compression level %d.",
280				    compression_level);
281				break;
282			}
283			if (!options.compression) {
284				debug2("compression disabled");
285				break;
286			}
287			/* Enable compression after we have responded with SUCCESS. */
288			enable_compression_after_reply = 1;
289			success = 1;
290			break;
291
292		case SSH_CMSG_REQUEST_PTY:
293			success = session_pty_req(s);
294			break;
295
296		case SSH_CMSG_X11_REQUEST_FORWARDING:
297			s->auth_proto = packet_get_string(&proto_len);
298			s->auth_data = packet_get_string(&data_len);
299
300			screen_flag = packet_get_protocol_flags() &
301			    SSH_PROTOFLAG_SCREEN_NUMBER;
302			debug2("SSH_PROTOFLAG_SCREEN_NUMBER: %d", screen_flag);
303
304			if (packet_remaining() == 4) {
305				if (!screen_flag)
306					debug2("Buggy client: "
307					    "X11 screen flag missing");
308				s->screen = packet_get_int();
309			} else {
310				s->screen = 0;
311			}
312			packet_check_eom();
313			success = session_setup_x11fwd(s);
314			if (!success) {
315				xfree(s->auth_proto);
316				xfree(s->auth_data);
317				s->auth_proto = NULL;
318				s->auth_data = NULL;
319			}
320			break;
321
322		case SSH_CMSG_AGENT_REQUEST_FORWARDING:
323			if (no_agent_forwarding_flag || compat13) {
324				debug("Authentication agent forwarding not permitted for this authentication.");
325				break;
326			}
327			debug("Received authentication agent forwarding request.");
328			success = auth_input_request_forwarding(s->pw);
329			break;
330
331		case SSH_CMSG_PORT_FORWARD_REQUEST:
332			if (no_port_forwarding_flag) {
333				debug("Port forwarding not permitted for this authentication.");
334				break;
335			}
336			if (!options.allow_tcp_forwarding) {
337				debug("Port forwarding not permitted.");
338				break;
339			}
340			debug("Received TCP/IP port forwarding request.");
341			channel_input_port_forward_request(s->pw->pw_uid == 0, options.gateway_ports);
342			success = 1;
343			break;
344
345		case SSH_CMSG_MAX_PACKET_SIZE:
346			if (packet_set_maxsize(packet_get_int()) > 0)
347				success = 1;
348			break;
349
350#if defined(AFS) || defined(KRB5)
351		case SSH_CMSG_HAVE_KERBEROS_TGT:
352			if (!options.kerberos_tgt_passing) {
353				verbose("Kerberos TGT passing disabled.");
354			} else {
355				char *kdata = packet_get_string(&dlen);
356				packet_check_eom();
357
358				/* XXX - 0x41, see creds_to_radix version */
359				if (kdata[0] != 0x41) {
360#ifdef KRB5
361					krb5_data tgt;
362					tgt.data = kdata;
363					tgt.length = dlen;
364
365					if (auth_krb5_tgt(s->authctxt, &tgt))
366						success = 1;
367					else
368						verbose("Kerberos v5 TGT refused for %.100s", s->authctxt->user);
369#endif /* KRB5 */
370				} else {
371#ifdef AFS
372					if (auth_krb4_tgt(s->authctxt, kdata))
373						success = 1;
374					else
375						verbose("Kerberos v4 TGT refused for %.100s", s->authctxt->user);
376#endif /* AFS */
377				}
378				xfree(kdata);
379			}
380			break;
381#endif /* AFS || KRB5 */
382
383#ifdef AFS
384		case SSH_CMSG_HAVE_AFS_TOKEN:
385			if (!options.afs_token_passing || !k_hasafs()) {
386				verbose("AFS token passing disabled.");
387			} else {
388				/* Accept AFS token. */
389				char *token = packet_get_string(&dlen);
390				packet_check_eom();
391
392				if (auth_afs_token(s->authctxt, token))
393					success = 1;
394				else
395					verbose("AFS token refused for %.100s",
396					    s->authctxt->user);
397				xfree(token);
398			}
399			break;
400#endif /* AFS */
401
402		case SSH_CMSG_EXEC_SHELL:
403		case SSH_CMSG_EXEC_CMD:
404			if (type == SSH_CMSG_EXEC_CMD) {
405				command = packet_get_string(&dlen);
406				debug("Exec command '%.500s'", command);
407				do_exec(s, command);
408				xfree(command);
409			} else {
410				do_exec(s, NULL);
411			}
412			packet_check_eom();
413			session_close(s);
414			return;
415
416		default:
417			/*
418			 * Any unknown messages in this phase are ignored,
419			 * and a failure message is returned.
420			 */
421			log("Unknown packet type received after authentication: %d", type);
422		}
423		packet_start(success ? SSH_SMSG_SUCCESS : SSH_SMSG_FAILURE);
424		packet_send();
425		packet_write_wait();
426
427		/* Enable compression now that we have replied if appropriate. */
428		if (enable_compression_after_reply) {
429			enable_compression_after_reply = 0;
430			packet_start_compression(compression_level);
431		}
432	}
433}
434
435/*
436 * This is called to fork and execute a command when we have no tty.  This
437 * will call do_child from the child, and server_loop from the parent after
438 * setting up file descriptors and such.
439 */
440void
441do_exec_no_pty(Session *s, const char *command)
442{
443	pid_t pid;
444
445#ifdef USE_PIPES
446	int pin[2], pout[2], perr[2];
447	/* Allocate pipes for communicating with the program. */
448	if (pipe(pin) < 0 || pipe(pout) < 0 || pipe(perr) < 0)
449		packet_disconnect("Could not create pipes: %.100s",
450				  strerror(errno));
451#else /* USE_PIPES */
452	int inout[2], err[2];
453	/* Uses socket pairs to communicate with the program. */
454	if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) < 0 ||
455	    socketpair(AF_UNIX, SOCK_STREAM, 0, err) < 0)
456		packet_disconnect("Could not create socket pairs: %.100s",
457				  strerror(errno));
458#endif /* USE_PIPES */
459	if (s == NULL)
460		fatal("do_exec_no_pty: no session");
461
462	session_proctitle(s);
463
464#if defined(USE_PAM)
465	do_pam_session(s->pw->pw_name, NULL);
466	do_pam_setcred(1);
467	if (is_pam_password_change_required())
468		packet_disconnect("Password change required but no "
469		    "TTY available");
470#endif /* USE_PAM */
471
472	/* Fork the child. */
473	if ((pid = fork()) == 0) {
474		/* Child.  Reinitialize the log since the pid has changed. */
475		log_init(__progname, options.log_level, options.log_facility, log_stderr);
476
477		/*
478		 * Create a new session and process group since the 4.4BSD
479		 * setlogin() affects the entire process group.
480		 */
481		if (setsid() < 0)
482			error("setsid failed: %.100s", strerror(errno));
483
484#ifdef USE_PIPES
485		/*
486		 * Redirect stdin.  We close the parent side of the socket
487		 * pair, and make the child side the standard input.
488		 */
489		close(pin[1]);
490		if (dup2(pin[0], 0) < 0)
491			perror("dup2 stdin");
492		close(pin[0]);
493
494		/* Redirect stdout. */
495		close(pout[0]);
496		if (dup2(pout[1], 1) < 0)
497			perror("dup2 stdout");
498		close(pout[1]);
499
500		/* Redirect stderr. */
501		close(perr[0]);
502		if (dup2(perr[1], 2) < 0)
503			perror("dup2 stderr");
504		close(perr[1]);
505#else /* USE_PIPES */
506		/*
507		 * Redirect stdin, stdout, and stderr.  Stdin and stdout will
508		 * use the same socket, as some programs (particularly rdist)
509		 * seem to depend on it.
510		 */
511		close(inout[1]);
512		close(err[1]);
513		if (dup2(inout[0], 0) < 0)	/* stdin */
514			perror("dup2 stdin");
515		if (dup2(inout[0], 1) < 0)	/* stdout.  Note: same socket as stdin. */
516			perror("dup2 stdout");
517		if (dup2(err[0], 2) < 0)	/* stderr */
518			perror("dup2 stderr");
519#endif /* USE_PIPES */
520
521		/* Do processing for the child (exec command etc). */
522		do_child(s, command);
523		/* NOTREACHED */
524	}
525#ifdef HAVE_CYGWIN
526	if (is_winnt)
527		cygwin_set_impersonation_token(INVALID_HANDLE_VALUE);
528#endif
529	if (pid < 0)
530		packet_disconnect("fork failed: %.100s", strerror(errno));
531	s->pid = pid;
532	/* Set interactive/non-interactive mode. */
533	packet_set_interactive(s->display != NULL);
534#ifdef USE_PIPES
535	/* We are the parent.  Close the child sides of the pipes. */
536	close(pin[0]);
537	close(pout[1]);
538	close(perr[1]);
539
540	if (compat20) {
541		session_set_fds(s, pin[1], pout[0], s->is_subsystem ? -1 : perr[0]);
542	} else {
543		/* Enter the interactive session. */
544		server_loop(pid, pin[1], pout[0], perr[0]);
545		/* server_loop has closed pin[1], pout[0], and perr[0]. */
546	}
547#else /* USE_PIPES */
548	/* We are the parent.  Close the child sides of the socket pairs. */
549	close(inout[0]);
550	close(err[0]);
551
552	/*
553	 * Enter the interactive session.  Note: server_loop must be able to
554	 * handle the case that fdin and fdout are the same.
555	 */
556	if (compat20) {
557		session_set_fds(s, inout[1], inout[1], s->is_subsystem ? -1 : err[1]);
558	} else {
559		server_loop(pid, inout[1], inout[1], err[1]);
560		/* server_loop has closed inout[1] and err[1]. */
561	}
562#endif /* USE_PIPES */
563}
564
565/*
566 * This is called to fork and execute a command when we have a tty.  This
567 * will call do_child from the child, and server_loop from the parent after
568 * setting up file descriptors, controlling tty, updating wtmp, utmp,
569 * lastlog, and other such operations.
570 */
571void
572do_exec_pty(Session *s, const char *command)
573{
574	int fdout, ptyfd, ttyfd, ptymaster;
575	pid_t pid;
576
577	if (s == NULL)
578		fatal("do_exec_pty: no session");
579	ptyfd = s->ptyfd;
580	ttyfd = s->ttyfd;
581
582#if defined(USE_PAM)
583	do_pam_session(s->pw->pw_name, s->tty);
584	do_pam_setcred(1);
585#endif
586
587	/* Fork the child. */
588	if ((pid = fork()) == 0) {
589
590		/* Child.  Reinitialize the log because the pid has changed. */
591		log_init(__progname, options.log_level, options.log_facility, log_stderr);
592		/* Close the master side of the pseudo tty. */
593		close(ptyfd);
594
595		/* Make the pseudo tty our controlling tty. */
596		pty_make_controlling_tty(&ttyfd, s->tty);
597
598		/* Redirect stdin/stdout/stderr from the pseudo tty. */
599		if (dup2(ttyfd, 0) < 0)
600			error("dup2 stdin: %s", strerror(errno));
601		if (dup2(ttyfd, 1) < 0)
602			error("dup2 stdout: %s", strerror(errno));
603		if (dup2(ttyfd, 2) < 0)
604			error("dup2 stderr: %s", strerror(errno));
605
606		/* Close the extra descriptor for the pseudo tty. */
607		close(ttyfd);
608
609		/* record login, etc. similar to login(1) */
610#ifndef HAVE_OSF_SIA
611		if (!(options.use_login && command == NULL))
612			do_login(s, command);
613# ifdef LOGIN_NEEDS_UTMPX
614		else
615			do_pre_login(s);
616# endif
617#endif
618
619		/* Do common processing for the child, such as execing the command. */
620		do_child(s, command);
621		/* NOTREACHED */
622	}
623#ifdef HAVE_CYGWIN
624	if (is_winnt)
625		cygwin_set_impersonation_token(INVALID_HANDLE_VALUE);
626#endif
627	if (pid < 0)
628		packet_disconnect("fork failed: %.100s", strerror(errno));
629	s->pid = pid;
630
631	/* Parent.  Close the slave side of the pseudo tty. */
632	close(ttyfd);
633
634	/*
635	 * Create another descriptor of the pty master side for use as the
636	 * standard input.  We could use the original descriptor, but this
637	 * simplifies code in server_loop.  The descriptor is bidirectional.
638	 */
639	fdout = dup(ptyfd);
640	if (fdout < 0)
641		packet_disconnect("dup #1 failed: %.100s", strerror(errno));
642
643	/* we keep a reference to the pty master */
644	ptymaster = dup(ptyfd);
645	if (ptymaster < 0)
646		packet_disconnect("dup #2 failed: %.100s", strerror(errno));
647	s->ptymaster = ptymaster;
648
649	/* Enter interactive session. */
650	packet_set_interactive(1);
651	if (compat20) {
652		session_set_fds(s, ptyfd, fdout, -1);
653	} else {
654		server_loop(pid, ptyfd, fdout, -1);
655		/* server_loop _has_ closed ptyfd and fdout. */
656	}
657}
658
659#ifdef LOGIN_NEEDS_UTMPX
660static void
661do_pre_login(Session *s)
662{
663	socklen_t fromlen;
664	struct sockaddr_storage from;
665	pid_t pid = getpid();
666
667	/*
668	 * Get IP address of client. If the connection is not a socket, let
669	 * the address be 0.0.0.0.
670	 */
671	memset(&from, 0, sizeof(from));
672	if (packet_connection_is_on_socket()) {
673		fromlen = sizeof(from);
674		if (getpeername(packet_get_connection_in(),
675		    (struct sockaddr *) & from, &fromlen) < 0) {
676			debug("getpeername: %.100s", strerror(errno));
677			fatal_cleanup();
678		}
679	}
680
681	record_utmp_only(pid, s->tty, s->pw->pw_name,
682	    get_remote_name_or_ip(utmp_len, options.verify_reverse_mapping),
683	    (struct sockaddr *)&from);
684}
685#endif
686
687/*
688 * This is called to fork and execute a command.  If another command is
689 * to be forced, execute that instead.
690 */
691void
692do_exec(Session *s, const char *command)
693{
694	if (forced_command) {
695		original_command = command;
696		command = forced_command;
697		debug("Forced command '%.900s'", command);
698	}
699
700	if (s->ttyfd != -1)
701		do_exec_pty(s, command);
702	else
703		do_exec_no_pty(s, command);
704
705	original_command = NULL;
706}
707
708
709/* administrative, login(1)-like work */
710void
711do_login(Session *s, const char *command)
712{
713	char *time_string;
714	socklen_t fromlen;
715	struct sockaddr_storage from;
716	struct passwd * pw = s->pw;
717	pid_t pid = getpid();
718
719	/*
720	 * Get IP address of client. If the connection is not a socket, let
721	 * the address be 0.0.0.0.
722	 */
723	memset(&from, 0, sizeof(from));
724	if (packet_connection_is_on_socket()) {
725		fromlen = sizeof(from);
726		if (getpeername(packet_get_connection_in(),
727		    (struct sockaddr *) & from, &fromlen) < 0) {
728			debug("getpeername: %.100s", strerror(errno));
729			fatal_cleanup();
730		}
731	}
732
733	/* Record that there was a login on that tty from the remote host. */
734	if (!use_privsep)
735		record_login(pid, s->tty, pw->pw_name, pw->pw_uid,
736		    get_remote_name_or_ip(utmp_len,
737		    options.verify_reverse_mapping),
738		    (struct sockaddr *)&from);
739
740#ifdef USE_PAM
741	/*
742	 * If password change is needed, do it now.
743	 * This needs to occur before the ~/.hushlogin check.
744	 */
745	if (is_pam_password_change_required()) {
746		print_pam_messages();
747		do_pam_chauthtok();
748	}
749#endif
750
751	if (check_quietlogin(s, command))
752		return;
753
754#ifdef USE_PAM
755	if (!is_pam_password_change_required())
756		print_pam_messages();
757#endif /* USE_PAM */
758#ifdef WITH_AIXAUTHENTICATE
759	if (aixloginmsg && *aixloginmsg)
760		printf("%s\n", aixloginmsg);
761#endif /* WITH_AIXAUTHENTICATE */
762
763	if (options.print_lastlog && s->last_login_time != 0) {
764		time_string = ctime(&s->last_login_time);
765		if (strchr(time_string, '\n'))
766			*strchr(time_string, '\n') = 0;
767		if (strcmp(s->hostname, "") == 0)
768			printf("Last login: %s\r\n", time_string);
769		else
770			printf("Last login: %s from %s\r\n", time_string,
771			    s->hostname);
772	}
773
774	do_motd();
775}
776
777/*
778 * Display the message of the day.
779 */
780void
781do_motd(void)
782{
783	FILE *f;
784	char buf[256];
785
786	if (options.print_motd) {
787#ifdef HAVE_LOGIN_CAP
788		f = fopen(login_getcapstr(lc, "welcome", "/etc/motd",
789		    "/etc/motd"), "r");
790#else
791		f = fopen("/etc/motd", "r");
792#endif
793		if (f) {
794			while (fgets(buf, sizeof(buf), f))
795				fputs(buf, stdout);
796			fclose(f);
797		}
798	}
799}
800
801
802/*
803 * Check for quiet login, either .hushlogin or command given.
804 */
805int
806check_quietlogin(Session *s, const char *command)
807{
808	char buf[256];
809	struct passwd *pw = s->pw;
810	struct stat st;
811
812	/* Return 1 if .hushlogin exists or a command given. */
813	if (command != NULL)
814		return 1;
815	snprintf(buf, sizeof(buf), "%.200s/.hushlogin", pw->pw_dir);
816#ifdef HAVE_LOGIN_CAP
817	if (login_getcapbool(lc, "hushlogin", 0) || stat(buf, &st) >= 0)
818		return 1;
819#else
820	if (stat(buf, &st) >= 0)
821		return 1;
822#endif
823	return 0;
824}
825
826/*
827 * Sets the value of the given variable in the environment.  If the variable
828 * already exists, its value is overriden.
829 */
830static void
831child_set_env(char ***envp, u_int *envsizep, const char *name,
832	const char *value)
833{
834	u_int i, namelen;
835	char **env;
836
837	/*
838	 * Find the slot where the value should be stored.  If the variable
839	 * already exists, we reuse the slot; otherwise we append a new slot
840	 * at the end of the array, expanding if necessary.
841	 */
842	env = *envp;
843	namelen = strlen(name);
844	for (i = 0; env[i]; i++)
845		if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=')
846			break;
847	if (env[i]) {
848		/* Reuse the slot. */
849		xfree(env[i]);
850	} else {
851		/* New variable.  Expand if necessary. */
852		if (i >= (*envsizep) - 1) {
853			if (*envsizep >= 1000)
854				fatal("child_set_env: too many env vars,"
855				    " skipping: %.100s", name);
856			(*envsizep) += 50;
857			env = (*envp) = xrealloc(env, (*envsizep) * sizeof(char *));
858		}
859		/* Need to set the NULL pointer at end of array beyond the new slot. */
860		env[i + 1] = NULL;
861	}
862
863	/* Allocate space and format the variable in the appropriate slot. */
864	env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1);
865	snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value);
866}
867
868/*
869 * Reads environment variables from the given file and adds/overrides them
870 * into the environment.  If the file does not exist, this does nothing.
871 * Otherwise, it must consist of empty lines, comments (line starts with '#')
872 * and assignments of the form name=value.  No other forms are allowed.
873 */
874static void
875read_environment_file(char ***env, u_int *envsize,
876	const char *filename)
877{
878	FILE *f;
879	char buf[4096];
880	char *cp, *value;
881	u_int lineno = 0;
882
883	f = fopen(filename, "r");
884	if (!f)
885		return;
886
887	while (fgets(buf, sizeof(buf), f)) {
888		if (++lineno > 1000)
889			fatal("Too many lines in environment file %s", filename);
890		for (cp = buf; *cp == ' ' || *cp == '\t'; cp++)
891			;
892		if (!*cp || *cp == '#' || *cp == '\n')
893			continue;
894		if (strchr(cp, '\n'))
895			*strchr(cp, '\n') = '\0';
896		value = strchr(cp, '=');
897		if (value == NULL) {
898			fprintf(stderr, "Bad line %u in %.100s\n", lineno,
899			    filename);
900			continue;
901		}
902		/*
903		 * Replace the equals sign by nul, and advance value to
904		 * the value string.
905		 */
906		*value = '\0';
907		value++;
908		child_set_env(env, envsize, cp, value);
909	}
910	fclose(f);
911}
912
913void copy_environment(char **source, char ***env, u_int *envsize)
914{
915	char *var_name, *var_val;
916	int i;
917
918	if (source == NULL)
919		return;
920
921	for(i = 0; source[i] != NULL; i++) {
922		var_name = xstrdup(source[i]);
923		if ((var_val = strstr(var_name, "=")) == NULL) {
924			xfree(var_name);
925			continue;
926		}
927		*var_val++ = '\0';
928
929		debug3("Copy environment: %s=%s", var_name, var_val);
930		child_set_env(env, envsize, var_name, var_val);
931
932		xfree(var_name);
933	}
934}
935
936static char **
937do_setup_env(Session *s, const char *shell)
938{
939	char buf[256];
940	u_int i, envsize;
941	char **env;
942#ifdef HAVE_LOGIN_CAP
943	extern char **environ;
944	char **senv, **var;
945#endif
946	struct passwd *pw = s->pw;
947
948	/* Initialize the environment. */
949	envsize = 100;
950	env = xmalloc(envsize * sizeof(char *));
951	env[0] = NULL;
952
953#ifdef HAVE_CYGWIN
954	/*
955	 * The Windows environment contains some setting which are
956	 * important for a running system. They must not be dropped.
957	 */
958	copy_environment(environ, &env, &envsize);
959#endif
960
961	if (getenv("TZ"))
962		child_set_env(&env, &envsize, "TZ", getenv("TZ"));
963	if (!options.use_login) {
964		/* Set basic environment. */
965		child_set_env(&env, &envsize, "USER", pw->pw_name);
966		child_set_env(&env, &envsize, "LOGNAME", pw->pw_name);
967		child_set_env(&env, &envsize, "HOME", pw->pw_dir);
968		snprintf(buf, sizeof buf, "%.200s/%.50s",
969			 _PATH_MAILDIR, pw->pw_name);
970		child_set_env(&env, &envsize, "MAIL", buf);
971#ifdef HAVE_LOGIN_CAP
972		child_set_env(&env, &envsize, "PATH", _PATH_STDPATH);
973		child_set_env(&env, &envsize, "TERM", "su");
974		senv = environ;
975		environ = xmalloc(sizeof(char *));
976		*environ = NULL;
977		(void) setusercontext(lc, pw, pw->pw_uid,
978		    LOGIN_SETENV|LOGIN_SETPATH);
979		copy_environment(environ, &env, &envsize);
980		for (var = environ; *var != NULL; ++var)
981			xfree(*var);
982		xfree(environ);
983		environ = senv;
984#else /* HAVE_LOGIN_CAP */
985# ifndef HAVE_CYGWIN
986		/*
987		 * There's no standard path on Windows. The path contains
988		 * important components pointing to the system directories,
989		 * needed for loading shared libraries. So the path better
990		 * remains intact here.
991		 */
992#  ifdef SUPERUSER_PATH
993		child_set_env(&env, &envsize, "PATH",
994		    s->pw->pw_uid == 0 ? SUPERUSER_PATH : _PATH_STDPATH);
995#  else
996		child_set_env(&env, &envsize, "PATH", _PATH_STDPATH);
997#  endif /* SUPERUSER_PATH */
998# endif /* HAVE_CYGWIN */
999#endif /* HAVE_LOGIN_CAP */
1000
1001		/* Normal systems set SHELL by default. */
1002		child_set_env(&env, &envsize, "SHELL", shell);
1003	}
1004
1005	/* Set custom environment options from RSA authentication. */
1006	if (!options.use_login) {
1007		while (custom_environment) {
1008			struct envstring *ce = custom_environment;
1009			char *s = ce->s;
1010
1011			for (i = 0; s[i] != '=' && s[i]; i++)
1012				;
1013			if (s[i] == '=') {
1014				s[i] = 0;
1015				child_set_env(&env, &envsize, s, s + i + 1);
1016			}
1017			custom_environment = ce->next;
1018			xfree(ce->s);
1019			xfree(ce);
1020		}
1021	}
1022
1023	snprintf(buf, sizeof buf, "%.50s %d %d",
1024	    get_remote_ipaddr(), get_remote_port(), get_local_port());
1025	child_set_env(&env, &envsize, "SSH_CLIENT", buf);
1026
1027	if (s->ttyfd != -1)
1028		child_set_env(&env, &envsize, "SSH_TTY", s->tty);
1029	if (s->term)
1030		child_set_env(&env, &envsize, "TERM", s->term);
1031	if (s->display)
1032		child_set_env(&env, &envsize, "DISPLAY", s->display);
1033	if (original_command)
1034		child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND",
1035		    original_command);
1036
1037#ifdef _AIX
1038	{
1039		char *cp;
1040
1041		if ((cp = getenv("AUTHSTATE")) != NULL)
1042			child_set_env(&env, &envsize, "AUTHSTATE", cp);
1043		if ((cp = getenv("KRB5CCNAME")) != NULL)
1044			child_set_env(&env, &envsize, "KRB5CCNAME", cp);
1045		read_environment_file(&env, &envsize, "/etc/environment");
1046	}
1047#endif
1048#ifdef KRB4
1049	if (s->authctxt->krb4_ticket_file)
1050		child_set_env(&env, &envsize, "KRBTKFILE",
1051		    s->authctxt->krb4_ticket_file);
1052#endif
1053#ifdef KRB5
1054	if (s->authctxt->krb5_ticket_file)
1055		child_set_env(&env, &envsize, "KRB5CCNAME",
1056		    s->authctxt->krb5_ticket_file);
1057#endif
1058#ifdef USE_PAM
1059	/* Pull in any environment variables that may have been set by PAM. */
1060	copy_environment(fetch_pam_environment(), &env, &envsize);
1061#endif /* USE_PAM */
1062
1063	if (auth_sock_name != NULL)
1064		child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME,
1065		    auth_sock_name);
1066
1067	/* read $HOME/.ssh/environment. */
1068	if (!options.use_login) {
1069		snprintf(buf, sizeof buf, "%.200s/.ssh/environment",
1070		    pw->pw_dir);
1071		read_environment_file(&env, &envsize, buf);
1072	}
1073	if (debug_flag) {
1074		/* dump the environment */
1075		fprintf(stderr, "Environment:\n");
1076		for (i = 0; env[i]; i++)
1077			fprintf(stderr, "  %.200s\n", env[i]);
1078	}
1079	return env;
1080}
1081
1082/*
1083 * Run $HOME/.ssh/rc, /etc/ssh/sshrc, or xauth (whichever is found
1084 * first in this order).
1085 */
1086static void
1087do_rc_files(Session *s, const char *shell)
1088{
1089	FILE *f = NULL;
1090	char cmd[1024];
1091	int do_xauth;
1092	struct stat st;
1093
1094	do_xauth =
1095	    s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL;
1096
1097	/* ignore _PATH_SSH_USER_RC for subsystems */
1098	if (!s->is_subsystem && (stat(_PATH_SSH_USER_RC, &st) >= 0)) {
1099		snprintf(cmd, sizeof cmd, "%s -c '%s %s'",
1100		    shell, _PATH_BSHELL, _PATH_SSH_USER_RC);
1101		if (debug_flag)
1102			fprintf(stderr, "Running %s\n", cmd);
1103		f = popen(cmd, "w");
1104		if (f) {
1105			if (do_xauth)
1106				fprintf(f, "%s %s\n", s->auth_proto,
1107				    s->auth_data);
1108			pclose(f);
1109		} else
1110			fprintf(stderr, "Could not run %s\n",
1111			    _PATH_SSH_USER_RC);
1112	} else if (stat(_PATH_SSH_SYSTEM_RC, &st) >= 0) {
1113		if (debug_flag)
1114			fprintf(stderr, "Running %s %s\n", _PATH_BSHELL,
1115			    _PATH_SSH_SYSTEM_RC);
1116		f = popen(_PATH_BSHELL " " _PATH_SSH_SYSTEM_RC, "w");
1117		if (f) {
1118			if (do_xauth)
1119				fprintf(f, "%s %s\n", s->auth_proto,
1120				    s->auth_data);
1121			pclose(f);
1122		} else
1123			fprintf(stderr, "Could not run %s\n",
1124			    _PATH_SSH_SYSTEM_RC);
1125	} else if (do_xauth && options.xauth_location != NULL) {
1126		/* Add authority data to .Xauthority if appropriate. */
1127		if (debug_flag) {
1128			fprintf(stderr,
1129			    "Running %.500s add "
1130			    "%.100s %.100s %.100s\n",
1131			    options.xauth_location, s->auth_display,
1132			    s->auth_proto, s->auth_data);
1133		}
1134		snprintf(cmd, sizeof cmd, "%s -q -",
1135		    options.xauth_location);
1136		f = popen(cmd, "w");
1137		if (f) {
1138			fprintf(f, "add %s %s %s\n",
1139			    s->auth_display, s->auth_proto,
1140			    s->auth_data);
1141			pclose(f);
1142		} else {
1143			fprintf(stderr, "Could not run %s\n",
1144			    cmd);
1145		}
1146	}
1147}
1148
1149static void
1150do_nologin(struct passwd *pw)
1151{
1152	FILE *f = NULL;
1153	char buf[1024];
1154
1155#ifdef HAVE_LOGIN_CAP
1156	if (!login_getcapbool(lc, "ignorenologin", 0) && pw->pw_uid)
1157		f = fopen(login_getcapstr(lc, "nologin", _PATH_NOLOGIN,
1158		    _PATH_NOLOGIN), "r");
1159#else
1160	if (pw->pw_uid)
1161		f = fopen(_PATH_NOLOGIN, "r");
1162#endif
1163	if (f) {
1164		/* /etc/nologin exists.  Print its contents and exit. */
1165		while (fgets(buf, sizeof(buf), f))
1166			fputs(buf, stderr);
1167		fclose(f);
1168		exit(254);
1169	}
1170}
1171
1172/* Set login name, uid, gid, and groups. */
1173void
1174do_setusercontext(struct passwd *pw)
1175{
1176	char tty='\0';
1177
1178#ifdef HAVE_CYGWIN
1179	if (is_winnt) {
1180#else /* HAVE_CYGWIN */
1181	if (getuid() == 0 || geteuid() == 0) {
1182#endif /* HAVE_CYGWIN */
1183#ifdef HAVE_SETPCRED
1184		setpcred(pw->pw_name);
1185#endif /* HAVE_SETPCRED */
1186#ifdef HAVE_LOGIN_CAP
1187#ifdef __bsdi__
1188		setpgid(0, 0);
1189#endif
1190		if (setusercontext(lc, pw, pw->pw_uid,
1191		    (LOGIN_SETALL & ~(LOGIN_SETENV|LOGIN_SETPATH))) < 0) {
1192			perror("unable to set user context");
1193			exit(1);
1194		}
1195#else
1196# if defined(HAVE_GETLUID) && defined(HAVE_SETLUID)
1197		/* Sets login uid for accounting */
1198		if (getluid() == -1 && setluid(pw->pw_uid) == -1)
1199			error("setluid: %s", strerror(errno));
1200# endif /* defined(HAVE_GETLUID) && defined(HAVE_SETLUID) */
1201
1202		if (setlogin(pw->pw_name) < 0)
1203			error("setlogin failed: %s", strerror(errno));
1204		if (setgid(pw->pw_gid) < 0) {
1205			perror("setgid");
1206			exit(1);
1207		}
1208		/* Initialize the group list. */
1209		if (initgroups(pw->pw_name, pw->pw_gid) < 0) {
1210			perror("initgroups");
1211			exit(1);
1212		}
1213		endgrent();
1214# ifdef USE_PAM
1215		/*
1216		 * PAM credentials may take the form of supplementary groups.
1217		 * These will have been wiped by the above initgroups() call.
1218		 * Reestablish them here.
1219		 */
1220		do_pam_setcred(0);
1221# endif /* USE_PAM */
1222# if defined(WITH_IRIX_PROJECT) || defined(WITH_IRIX_JOBS) || defined(WITH_IRIX_ARRAY)
1223		irix_setusercontext(pw);
1224#  endif /* defined(WITH_IRIX_PROJECT) || defined(WITH_IRIX_JOBS) || defined(WITH_IRIX_ARRAY) */
1225# ifdef _AIX
1226		/* XXX: Disable tty setting.  Enabled if required later */
1227		aix_usrinfo(pw, &tty, -1);
1228# endif /* _AIX */
1229		/* Permanently switch to the desired uid. */
1230		permanently_set_uid(pw);
1231#endif
1232	}
1233	if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid)
1234		fatal("Failed to set uids to %u.", (u_int) pw->pw_uid);
1235}
1236
1237static void
1238launch_login(struct passwd *pw, const char *hostname)
1239{
1240	/* Launch login(1). */
1241
1242	execl(LOGIN_PROGRAM, "login", "-h", hostname,
1243#ifdef xxxLOGIN_NEEDS_TERM
1244		    (s->term ? s->term : "unknown"),
1245#endif /* LOGIN_NEEDS_TERM */
1246#ifdef LOGIN_NO_ENDOPT
1247	    "-p", "-f", pw->pw_name, (char *)NULL);
1248#else
1249	    "-p", "-f", "--", pw->pw_name, (char *)NULL);
1250#endif
1251
1252	/* Login couldn't be executed, die. */
1253
1254	perror("login");
1255	exit(1);
1256}
1257
1258/*
1259 * Performs common processing for the child, such as setting up the
1260 * environment, closing extra file descriptors, setting the user and group
1261 * ids, and executing the command or shell.
1262 */
1263void
1264do_child(Session *s, const char *command)
1265{
1266	extern char **environ;
1267	char **env;
1268	char *argv[10];
1269	const char *shell, *shell0, *hostname = NULL;
1270	struct passwd *pw = s->pw;
1271	u_int i;
1272
1273	/* remove hostkey from the child's memory */
1274	destroy_sensitive_data();
1275
1276	/* login(1) is only called if we execute the login shell */
1277	if (options.use_login && command != NULL)
1278		options.use_login = 0;
1279
1280	/*
1281	 * Login(1) does this as well, and it needs uid 0 for the "-h"
1282	 * switch, so we let login(1) to this for us.
1283	 */
1284	if (!options.use_login) {
1285#ifdef HAVE_OSF_SIA
1286		session_setup_sia(pw->pw_name, s->ttyfd == -1 ? NULL : s->tty);
1287		if (!check_quietlogin(s, command))
1288			do_motd();
1289#else /* HAVE_OSF_SIA */
1290		do_nologin(pw);
1291		do_setusercontext(pw);
1292#endif /* HAVE_OSF_SIA */
1293	}
1294
1295	/*
1296	 * Get the shell from the password data.  An empty shell field is
1297	 * legal, and means /bin/sh.
1298	 */
1299	shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;
1300#ifdef HAVE_LOGIN_CAP
1301	shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell);
1302#endif
1303
1304	env = do_setup_env(s, shell);
1305
1306	/* we have to stash the hostname before we close our socket. */
1307	if (options.use_login)
1308		hostname = get_remote_name_or_ip(utmp_len,
1309		    options.verify_reverse_mapping);
1310	/*
1311	 * Close the connection descriptors; note that this is the child, and
1312	 * the server will still have the socket open, and it is important
1313	 * that we do not shutdown it.  Note that the descriptors cannot be
1314	 * closed before building the environment, as we call
1315	 * get_remote_ipaddr there.
1316	 */
1317	if (packet_get_connection_in() == packet_get_connection_out())
1318		close(packet_get_connection_in());
1319	else {
1320		close(packet_get_connection_in());
1321		close(packet_get_connection_out());
1322	}
1323	/*
1324	 * Close all descriptors related to channels.  They will still remain
1325	 * open in the parent.
1326	 */
1327	/* XXX better use close-on-exec? -markus */
1328	channel_close_all();
1329
1330	/*
1331	 * Close any extra file descriptors.  Note that there may still be
1332	 * descriptors left by system functions.  They will be closed later.
1333	 */
1334	endpwent();
1335
1336	/*
1337	 * Close any extra open file descriptors so that we don\'t have them
1338	 * hanging around in clients.  Note that we want to do this after
1339	 * initgroups, because at least on Solaris 2.3 it leaves file
1340	 * descriptors open.
1341	 */
1342	for (i = 3; i < 64; i++)
1343		close(i);
1344
1345	/*
1346	 * Must take new environment into use so that .ssh/rc,
1347	 * /etc/ssh/sshrc and xauth are run in the proper environment.
1348	 */
1349	environ = env;
1350
1351#ifdef AFS
1352	/* Try to get AFS tokens for the local cell. */
1353	if (k_hasafs()) {
1354		char cell[64];
1355
1356		if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0)
1357			krb_afslog(cell, 0);
1358
1359		krb_afslog(0, 0);
1360	}
1361#endif /* AFS */
1362
1363	/* Change current directory to the user\'s home directory. */
1364	if (chdir(pw->pw_dir) < 0) {
1365		fprintf(stderr, "Could not chdir to home directory %s: %s\n",
1366		    pw->pw_dir, strerror(errno));
1367#ifdef HAVE_LOGIN_CAP
1368		if (login_getcapbool(lc, "requirehome", 0))
1369			exit(1);
1370#endif
1371	}
1372
1373	if (!options.use_login)
1374		do_rc_files(s, shell);
1375
1376	/* restore SIGPIPE for child */
1377	signal(SIGPIPE,  SIG_DFL);
1378
1379	if (options.use_login) {
1380		launch_login(pw, hostname);
1381		/* NEVERREACHED */
1382	}
1383
1384	/* Get the last component of the shell name. */
1385	if ((shell0 = strrchr(shell, '/')) != NULL)
1386		shell0++;
1387	else
1388		shell0 = shell;
1389
1390	/*
1391	 * If we have no command, execute the shell.  In this case, the shell
1392	 * name to be passed in argv[0] is preceded by '-' to indicate that
1393	 * this is a login shell.
1394	 */
1395	if (!command) {
1396		char argv0[256];
1397
1398		/* Start the shell.  Set initial character to '-'. */
1399		argv0[0] = '-';
1400
1401		if (strlcpy(argv0 + 1, shell0, sizeof(argv0) - 1)
1402		    >= sizeof(argv0) - 1) {
1403			errno = EINVAL;
1404			perror(shell);
1405			exit(1);
1406		}
1407
1408		/* Execute the shell. */
1409		argv[0] = argv0;
1410		argv[1] = NULL;
1411		execve(shell, argv, env);
1412
1413		/* Executing the shell failed. */
1414		perror(shell);
1415		exit(1);
1416	}
1417	/*
1418	 * Execute the command using the user's shell.  This uses the -c
1419	 * option to execute the command.
1420	 */
1421	argv[0] = (char *) shell0;
1422	argv[1] = "-c";
1423	argv[2] = (char *) command;
1424	argv[3] = NULL;
1425	execve(shell, argv, env);
1426	perror(shell);
1427	exit(1);
1428}
1429
1430Session *
1431session_new(void)
1432{
1433	int i;
1434	static int did_init = 0;
1435	if (!did_init) {
1436		debug("session_new: init");
1437		for (i = 0; i < MAX_SESSIONS; i++) {
1438			sessions[i].used = 0;
1439		}
1440		did_init = 1;
1441	}
1442	for (i = 0; i < MAX_SESSIONS; i++) {
1443		Session *s = &sessions[i];
1444		if (! s->used) {
1445			memset(s, 0, sizeof(*s));
1446			s->chanid = -1;
1447			s->ptyfd = -1;
1448			s->ttyfd = -1;
1449			s->used = 1;
1450			s->self = i;
1451			debug("session_new: session %d", i);
1452			return s;
1453		}
1454	}
1455	return NULL;
1456}
1457
1458static void
1459session_dump(void)
1460{
1461	int i;
1462	for (i = 0; i < MAX_SESSIONS; i++) {
1463		Session *s = &sessions[i];
1464		debug("dump: used %d session %d %p channel %d pid %ld",
1465		    s->used,
1466		    s->self,
1467		    s,
1468		    s->chanid,
1469		    (long)s->pid);
1470	}
1471}
1472
1473int
1474session_open(Authctxt *authctxt, int chanid)
1475{
1476	Session *s = session_new();
1477	debug("session_open: channel %d", chanid);
1478	if (s == NULL) {
1479		error("no more sessions");
1480		return 0;
1481	}
1482	s->authctxt = authctxt;
1483	s->pw = authctxt->pw;
1484	if (s->pw == NULL)
1485		fatal("no user for session %d", s->self);
1486	debug("session_open: session %d: link with channel %d", s->self, chanid);
1487	s->chanid = chanid;
1488	return 1;
1489}
1490
1491Session *
1492session_by_tty(char *tty)
1493{
1494	int i;
1495	for (i = 0; i < MAX_SESSIONS; i++) {
1496		Session *s = &sessions[i];
1497		if (s->used && s->ttyfd != -1 && strcmp(s->tty, tty) == 0) {
1498			debug("session_by_tty: session %d tty %s", i, tty);
1499			return s;
1500		}
1501	}
1502	debug("session_by_tty: unknown tty %.100s", tty);
1503	session_dump();
1504	return NULL;
1505}
1506
1507static Session *
1508session_by_channel(int id)
1509{
1510	int i;
1511	for (i = 0; i < MAX_SESSIONS; i++) {
1512		Session *s = &sessions[i];
1513		if (s->used && s->chanid == id) {
1514			debug("session_by_channel: session %d channel %d", i, id);
1515			return s;
1516		}
1517	}
1518	debug("session_by_channel: unknown channel %d", id);
1519	session_dump();
1520	return NULL;
1521}
1522
1523static Session *
1524session_by_pid(pid_t pid)
1525{
1526	int i;
1527	debug("session_by_pid: pid %ld", (long)pid);
1528	for (i = 0; i < MAX_SESSIONS; i++) {
1529		Session *s = &sessions[i];
1530		if (s->used && s->pid == pid)
1531			return s;
1532	}
1533	error("session_by_pid: unknown pid %ld", (long)pid);
1534	session_dump();
1535	return NULL;
1536}
1537
1538static int
1539session_window_change_req(Session *s)
1540{
1541	s->col = packet_get_int();
1542	s->row = packet_get_int();
1543	s->xpixel = packet_get_int();
1544	s->ypixel = packet_get_int();
1545	packet_check_eom();
1546	pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel);
1547	return 1;
1548}
1549
1550static int
1551session_pty_req(Session *s)
1552{
1553	u_int len;
1554	int n_bytes;
1555
1556	if (no_pty_flag) {
1557		debug("Allocating a pty not permitted for this authentication.");
1558		return 0;
1559	}
1560	if (s->ttyfd != -1) {
1561		packet_disconnect("Protocol error: you already have a pty.");
1562		return 0;
1563	}
1564	/* Get the time and hostname when the user last logged in. */
1565	if (options.print_lastlog) {
1566		s->hostname[0] = '\0';
1567		s->last_login_time = get_last_login_time(s->pw->pw_uid,
1568		    s->pw->pw_name, s->hostname, sizeof(s->hostname));
1569	}
1570
1571	s->term = packet_get_string(&len);
1572
1573	if (compat20) {
1574		s->col = packet_get_int();
1575		s->row = packet_get_int();
1576	} else {
1577		s->row = packet_get_int();
1578		s->col = packet_get_int();
1579	}
1580	s->xpixel = packet_get_int();
1581	s->ypixel = packet_get_int();
1582
1583	if (strcmp(s->term, "") == 0) {
1584		xfree(s->term);
1585		s->term = NULL;
1586	}
1587
1588	/* Allocate a pty and open it. */
1589	debug("Allocating pty.");
1590	if (!PRIVSEP(pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty)))) {
1591		if (s->term)
1592			xfree(s->term);
1593		s->term = NULL;
1594		s->ptyfd = -1;
1595		s->ttyfd = -1;
1596		error("session_pty_req: session %d alloc failed", s->self);
1597		return 0;
1598	}
1599	debug("session_pty_req: session %d alloc %s", s->self, s->tty);
1600
1601	/* for SSH1 the tty modes length is not given */
1602	if (!compat20)
1603		n_bytes = packet_remaining();
1604	tty_parse_modes(s->ttyfd, &n_bytes);
1605
1606	/*
1607	 * Add a cleanup function to clear the utmp entry and record logout
1608	 * time in case we call fatal() (e.g., the connection gets closed).
1609	 */
1610	fatal_add_cleanup(session_pty_cleanup, (void *)s);
1611	if (!use_privsep)
1612		pty_setowner(s->pw, s->tty);
1613
1614	/* Set window size from the packet. */
1615	pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel);
1616
1617	packet_check_eom();
1618	session_proctitle(s);
1619	return 1;
1620}
1621
1622static int
1623session_subsystem_req(Session *s)
1624{
1625	struct stat st;
1626	u_int len;
1627	int success = 0;
1628	char *cmd, *subsys = packet_get_string(&len);
1629	int i;
1630
1631	packet_check_eom();
1632	log("subsystem request for %.100s", subsys);
1633
1634	for (i = 0; i < options.num_subsystems; i++) {
1635		if (strcmp(subsys, options.subsystem_name[i]) == 0) {
1636			cmd = options.subsystem_command[i];
1637			if (stat(cmd, &st) < 0) {
1638				error("subsystem: cannot stat %s: %s", cmd,
1639				    strerror(errno));
1640				break;
1641			}
1642			debug("subsystem: exec() %s", cmd);
1643			s->is_subsystem = 1;
1644			do_exec(s, cmd);
1645			success = 1;
1646			break;
1647		}
1648	}
1649
1650	if (!success)
1651		log("subsystem request for %.100s failed, subsystem not found",
1652		    subsys);
1653
1654	xfree(subsys);
1655	return success;
1656}
1657
1658static int
1659session_x11_req(Session *s)
1660{
1661	int success;
1662
1663	s->single_connection = packet_get_char();
1664	s->auth_proto = packet_get_string(NULL);
1665	s->auth_data = packet_get_string(NULL);
1666	s->screen = packet_get_int();
1667	packet_check_eom();
1668
1669	success = session_setup_x11fwd(s);
1670	if (!success) {
1671		xfree(s->auth_proto);
1672		xfree(s->auth_data);
1673		s->auth_proto = NULL;
1674		s->auth_data = NULL;
1675	}
1676	return success;
1677}
1678
1679static int
1680session_shell_req(Session *s)
1681{
1682	packet_check_eom();
1683	do_exec(s, NULL);
1684	return 1;
1685}
1686
1687static int
1688session_exec_req(Session *s)
1689{
1690	u_int len;
1691	char *command = packet_get_string(&len);
1692	packet_check_eom();
1693	do_exec(s, command);
1694	xfree(command);
1695	return 1;
1696}
1697
1698static int
1699session_auth_agent_req(Session *s)
1700{
1701	static int called = 0;
1702	packet_check_eom();
1703	if (no_agent_forwarding_flag) {
1704		debug("session_auth_agent_req: no_agent_forwarding_flag");
1705		return 0;
1706	}
1707	if (called) {
1708		return 0;
1709	} else {
1710		called = 1;
1711		return auth_input_request_forwarding(s->pw);
1712	}
1713}
1714
1715int
1716session_input_channel_req(Channel *c, const char *rtype)
1717{
1718	int success = 0;
1719	Session *s;
1720
1721	if ((s = session_by_channel(c->self)) == NULL) {
1722		log("session_input_channel_req: no session %d req %.100s",
1723		    c->self, rtype);
1724		return 0;
1725	}
1726	debug("session_input_channel_req: session %d req %s", s->self, rtype);
1727
1728	/*
1729	 * a session is in LARVAL state until a shell, a command
1730	 * or a subsystem is executed
1731	 */
1732	if (c->type == SSH_CHANNEL_LARVAL) {
1733		if (strcmp(rtype, "shell") == 0) {
1734			success = session_shell_req(s);
1735		} else if (strcmp(rtype, "exec") == 0) {
1736			success = session_exec_req(s);
1737		} else if (strcmp(rtype, "pty-req") == 0) {
1738			success =  session_pty_req(s);
1739		} else if (strcmp(rtype, "x11-req") == 0) {
1740			success = session_x11_req(s);
1741		} else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) {
1742			success = session_auth_agent_req(s);
1743		} else if (strcmp(rtype, "subsystem") == 0) {
1744			success = session_subsystem_req(s);
1745		}
1746	}
1747	if (strcmp(rtype, "window-change") == 0) {
1748		success = session_window_change_req(s);
1749	}
1750	return success;
1751}
1752
1753void
1754session_set_fds(Session *s, int fdin, int fdout, int fderr)
1755{
1756	if (!compat20)
1757		fatal("session_set_fds: called for proto != 2.0");
1758	/*
1759	 * now that have a child and a pipe to the child,
1760	 * we can activate our channel and register the fd's
1761	 */
1762	if (s->chanid == -1)
1763		fatal("no channel for session %d", s->self);
1764	channel_set_fds(s->chanid,
1765	    fdout, fdin, fderr,
1766	    fderr == -1 ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ,
1767	    1,
1768	    CHAN_SES_WINDOW_DEFAULT);
1769}
1770
1771/*
1772 * Function to perform pty cleanup. Also called if we get aborted abnormally
1773 * (e.g., due to a dropped connection).
1774 */
1775void
1776session_pty_cleanup2(void *session)
1777{
1778	Session *s = session;
1779
1780	if (s == NULL) {
1781		error("session_pty_cleanup: no session");
1782		return;
1783	}
1784	if (s->ttyfd == -1)
1785		return;
1786
1787	debug("session_pty_cleanup: session %d release %s", s->self, s->tty);
1788
1789	/* Record that the user has logged out. */
1790	if (s->pid != 0)
1791		record_logout(s->pid, s->tty, s->pw->pw_name);
1792
1793	/* Release the pseudo-tty. */
1794	if (getuid() == 0)
1795		pty_release(s->tty);
1796
1797	/*
1798	 * Close the server side of the socket pairs.  We must do this after
1799	 * the pty cleanup, so that another process doesn't get this pty
1800	 * while we're still cleaning up.
1801	 */
1802	if (close(s->ptymaster) < 0)
1803		error("close(s->ptymaster/%d): %s", s->ptymaster, strerror(errno));
1804
1805	/* unlink pty from session */
1806	s->ttyfd = -1;
1807}
1808
1809void
1810session_pty_cleanup(void *session)
1811{
1812	PRIVSEP(session_pty_cleanup2(session));
1813}
1814
1815static void
1816session_exit_message(Session *s, int status)
1817{
1818	Channel *c;
1819
1820	if ((c = channel_lookup(s->chanid)) == NULL)
1821		fatal("session_exit_message: session %d: no channel %d",
1822		    s->self, s->chanid);
1823	debug("session_exit_message: session %d channel %d pid %ld",
1824	    s->self, s->chanid, (long)s->pid);
1825
1826	if (WIFEXITED(status)) {
1827		channel_request_start(s->chanid, "exit-status", 0);
1828		packet_put_int(WEXITSTATUS(status));
1829		packet_send();
1830	} else if (WIFSIGNALED(status)) {
1831		channel_request_start(s->chanid, "exit-signal", 0);
1832		packet_put_int(WTERMSIG(status));
1833#ifdef WCOREDUMP
1834		packet_put_char(WCOREDUMP(status));
1835#else /* WCOREDUMP */
1836		packet_put_char(0);
1837#endif /* WCOREDUMP */
1838		packet_put_cstring("");
1839		packet_put_cstring("");
1840		packet_send();
1841	} else {
1842		/* Some weird exit cause.  Just exit. */
1843		packet_disconnect("wait returned status %04x.", status);
1844	}
1845
1846	/* disconnect channel */
1847	debug("session_exit_message: release channel %d", s->chanid);
1848	channel_cancel_cleanup(s->chanid);
1849	/*
1850	 * emulate a write failure with 'chan_write_failed', nobody will be
1851	 * interested in data we write.
1852	 * Note that we must not call 'chan_read_failed', since there could
1853	 * be some more data waiting in the pipe.
1854	 */
1855	if (c->ostate != CHAN_OUTPUT_CLOSED)
1856		chan_write_failed(c);
1857	s->chanid = -1;
1858}
1859
1860void
1861session_close(Session *s)
1862{
1863	debug("session_close: session %d pid %ld", s->self, (long)s->pid);
1864	if (s->ttyfd != -1) {
1865		fatal_remove_cleanup(session_pty_cleanup, (void *)s);
1866		session_pty_cleanup(s);
1867	}
1868	if (s->term)
1869		xfree(s->term);
1870	if (s->display)
1871		xfree(s->display);
1872	if (s->auth_display)
1873		xfree(s->auth_display);
1874	if (s->auth_data)
1875		xfree(s->auth_data);
1876	if (s->auth_proto)
1877		xfree(s->auth_proto);
1878	s->used = 0;
1879	session_proctitle(s);
1880}
1881
1882void
1883session_close_by_pid(pid_t pid, int status)
1884{
1885	Session *s = session_by_pid(pid);
1886	if (s == NULL) {
1887		debug("session_close_by_pid: no session for pid %ld",
1888		    (long)pid);
1889		return;
1890	}
1891	if (s->chanid != -1)
1892		session_exit_message(s, status);
1893	session_close(s);
1894}
1895
1896/*
1897 * this is called when a channel dies before
1898 * the session 'child' itself dies
1899 */
1900void
1901session_close_by_channel(int id, void *arg)
1902{
1903	Session *s = session_by_channel(id);
1904	if (s == NULL) {
1905		debug("session_close_by_channel: no session for id %d", id);
1906		return;
1907	}
1908	debug("session_close_by_channel: channel %d child %ld",
1909	    id, (long)s->pid);
1910	if (s->pid != 0) {
1911		debug("session_close_by_channel: channel %d: has child", id);
1912		/*
1913		 * delay detach of session, but release pty, since
1914		 * the fd's to the child are already closed
1915		 */
1916		if (s->ttyfd != -1) {
1917			fatal_remove_cleanup(session_pty_cleanup, (void *)s);
1918			session_pty_cleanup(s);
1919		}
1920		return;
1921	}
1922	/* detach by removing callback */
1923	channel_cancel_cleanup(s->chanid);
1924	s->chanid = -1;
1925	session_close(s);
1926}
1927
1928void
1929session_destroy_all(void (*closefunc)(Session *))
1930{
1931	int i;
1932	for (i = 0; i < MAX_SESSIONS; i++) {
1933		Session *s = &sessions[i];
1934		if (s->used) {
1935			if (closefunc != NULL)
1936				closefunc(s);
1937			else
1938				session_close(s);
1939		}
1940	}
1941}
1942
1943static char *
1944session_tty_list(void)
1945{
1946	static char buf[1024];
1947	int i;
1948	buf[0] = '\0';
1949	for (i = 0; i < MAX_SESSIONS; i++) {
1950		Session *s = &sessions[i];
1951		if (s->used && s->ttyfd != -1) {
1952			if (buf[0] != '\0')
1953				strlcat(buf, ",", sizeof buf);
1954			strlcat(buf, strrchr(s->tty, '/') + 1, sizeof buf);
1955		}
1956	}
1957	if (buf[0] == '\0')
1958		strlcpy(buf, "notty", sizeof buf);
1959	return buf;
1960}
1961
1962void
1963session_proctitle(Session *s)
1964{
1965	if (s->pw == NULL)
1966		error("no user for session %d", s->self);
1967	else
1968		setproctitle("%s@%s", s->pw->pw_name, session_tty_list());
1969}
1970
1971int
1972session_setup_x11fwd(Session *s)
1973{
1974	struct stat st;
1975	char display[512], auth_display[512];
1976	char hostname[MAXHOSTNAMELEN];
1977
1978	if (no_x11_forwarding_flag) {
1979		packet_send_debug("X11 forwarding disabled in user configuration file.");
1980		return 0;
1981	}
1982	if (!options.x11_forwarding) {
1983		debug("X11 forwarding disabled in server configuration file.");
1984		return 0;
1985	}
1986	if (!options.xauth_location ||
1987	    (stat(options.xauth_location, &st) == -1)) {
1988		packet_send_debug("No xauth program; cannot forward with spoofing.");
1989		return 0;
1990	}
1991	if (options.use_login) {
1992		packet_send_debug("X11 forwarding disabled; "
1993		    "not compatible with UseLogin=yes.");
1994		return 0;
1995	}
1996	if (s->display != NULL) {
1997		debug("X11 display already set.");
1998		return 0;
1999	}
2000	if (x11_create_display_inet(options.x11_display_offset,
2001	    options.x11_use_localhost, s->single_connection,
2002	    &s->display_number) == -1) {
2003		debug("x11_create_display_inet failed.");
2004		return 0;
2005	}
2006
2007	/* Set up a suitable value for the DISPLAY variable. */
2008	if (gethostname(hostname, sizeof(hostname)) < 0)
2009		fatal("gethostname: %.100s", strerror(errno));
2010	/*
2011	 * auth_display must be used as the displayname when the
2012	 * authorization entry is added with xauth(1).  This will be
2013	 * different than the DISPLAY string for localhost displays.
2014	 */
2015	if (options.x11_use_localhost) {
2016		snprintf(display, sizeof display, "localhost:%u.%u",
2017		    s->display_number, s->screen);
2018		snprintf(auth_display, sizeof auth_display, "unix:%u.%u",
2019		    s->display_number, s->screen);
2020		s->display = xstrdup(display);
2021		s->auth_display = xstrdup(auth_display);
2022	} else {
2023#ifdef IPADDR_IN_DISPLAY
2024		struct hostent *he;
2025		struct in_addr my_addr;
2026
2027		he = gethostbyname(hostname);
2028		if (he == NULL) {
2029			error("Can't get IP address for X11 DISPLAY.");
2030			packet_send_debug("Can't get IP address for X11 DISPLAY.");
2031			return 0;
2032		}
2033		memcpy(&my_addr, he->h_addr_list[0], sizeof(struct in_addr));
2034		snprintf(display, sizeof display, "%.50s:%u.%u", inet_ntoa(my_addr),
2035		    s->display_number, s->screen);
2036#else
2037		snprintf(display, sizeof display, "%.400s:%u.%u", hostname,
2038		    s->display_number, s->screen);
2039#endif
2040		s->display = xstrdup(display);
2041		s->auth_display = xstrdup(display);
2042	}
2043
2044	return 1;
2045}
2046
2047static void
2048do_authenticated2(Authctxt *authctxt)
2049{
2050	server_loop2(authctxt);
2051}
2052