[gssapi-openssh.git] / openssh / auth.c

/*
 * Copyright (c) 2000 Markus Friedl.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "includes.h"
RCSID("$OpenBSD: auth.c,v 1.35 2002/03/01 13:12:10 markus Exp $");

#ifdef HAVE_LOGIN_H
#include <login.h>
#endif
#if defined(HAVE_SHADOW_H) && !defined(DISABLE_SHADOW)
#include <shadow.h>
#endif /* defined(HAVE_SHADOW_H) && !defined(DISABLE_SHADOW) */

#ifdef HAVE_LIBGEN_H
#include <libgen.h>
#endif

#include "xmalloc.h"
#include "match.h"
#include "groupaccess.h"
#include "log.h"
#include "servconf.h"
#include "auth.h"
#include "auth-options.h"
#include "canohost.h"
#include "buffer.h"
#include "bufaux.h"
#include "uidswap.h"
#include "tildexpand.h"

/* import */
extern ServerOptions options;

/*
 * Check if the user is allowed to log in via ssh. If user is listed
 * in DenyUsers or one of user's groups is listed in DenyGroups, false
 * will be returned. If AllowUsers isn't empty and user isn't listed
 * there, or if AllowGroups isn't empty and one of user's groups isn't
 * listed there, false will be returned.
 * If the user's shell is not executable, false will be returned.
 * Otherwise true is returned.
 */
int
allowed_user(struct passwd * pw)
{
	struct stat st;
	const char *hostname = NULL, *ipaddr = NULL;
	char *shell;
	int i;
#ifdef WITH_AIXAUTHENTICATE
	char *loginmsg;
#endif /* WITH_AIXAUTHENTICATE */
#if !defined(USE_PAM) && defined(HAVE_SHADOW_H) && \
	!defined(DISABLE_SHADOW) && defined(HAS_SHADOW_EXPIRE)
	struct spwd *spw;

	/* Shouldn't be called if pw is NULL, but better safe than sorry... */
	if (!pw || !pw->pw_name)
		return 0;

	spw = getspnam(pw->pw_name);
	if (spw != NULL) {
		int days = time(NULL) / 86400;

		/* Check account expiry */
		if ((spw->sp_expire >= 0) && (days > spw->sp_expire))
			return 0;

		/* Check password expiry */
		if ((spw->sp_lstchg >= 0) && (spw->sp_max >= 0) &&
		    (days > (spw->sp_lstchg + spw->sp_max)))
			return 0;
	}
#else
	/* Shouldn't be called if pw is NULL, but better safe than sorry... */
	if (!pw || !pw->pw_name)
		return 0;
#endif

	/*
	 * Get the shell from the password data.  An empty shell field is
	 * legal, and means /bin/sh.
	 */
	shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;

	/* deny if shell does not exists or is not executable */
	if (stat(shell, &st) != 0) {
		log("User %.100s not allowed because shell %.100s does not exist",
		    pw->pw_name, shell);
		return 0;
	}
	if (!((st.st_mode & S_IFREG) && (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)))) {
		log("User %.100s not allowed because shell %.100s is not executable",
		    pw->pw_name, shell);
		return 0;
	}

	if (options.num_deny_users > 0 || options.num_allow_users > 0) {
		hostname = get_canonical_hostname(options.verify_reverse_mapping);
		ipaddr = get_remote_ipaddr();
	}

	/* Return false if user is listed in DenyUsers */
	if (options.num_deny_users > 0) {
		for (i = 0; i < options.num_deny_users; i++)
 			if (match_user(pw->pw_name, hostname, ipaddr,
			    options.deny_users[i])) {
 				log("User %.100s not allowed because listed in DenyUsers",
 				    pw->pw_name);
				return 0;
			}
	}
	/* Return false if AllowUsers isn't empty and user isn't listed there */
	if (options.num_allow_users > 0) {
		for (i = 0; i < options.num_allow_users; i++)
 			if (match_user(pw->pw_name, hostname, ipaddr,
			    options.allow_users[i]))
				break;
		/* i < options.num_allow_users iff we break for loop */
		if (i >= options.num_allow_users) {
			log("User %.100s not allowed because not listed in AllowUsers",
			    pw->pw_name);
			return 0;
		}
	}
	if (options.num_deny_groups > 0 || options.num_allow_groups > 0) {
		/* Get the user's group access list (primary and supplementary) */
		if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
			log("User %.100s not allowed because not in any group",
			    pw->pw_name);
			return 0;
		}

		/* Return false if one of user's groups is listed in DenyGroups */
		if (options.num_deny_groups > 0)
			if (ga_match(options.deny_groups,
			    options.num_deny_groups)) {
				ga_free();
				log("User %.100s not allowed because a group is listed in DenyGroups",
				    pw->pw_name);
				return 0;
			}
		/*
		 * Return false if AllowGroups isn't empty and one of user's groups
		 * isn't listed there
		 */
		if (options.num_allow_groups > 0)
			if (!ga_match(options.allow_groups,
			    options.num_allow_groups)) {
				ga_free();
				log("User %.100s not allowed because none of user's groups are listed in AllowGroups",
				    pw->pw_name);
				return 0;
			}
		ga_free();
	}

#ifdef WITH_AIXAUTHENTICATE
	if (loginrestrictions(pw->pw_name, S_RLOGIN, NULL, &loginmsg) != 0) {
		if (loginmsg && *loginmsg) {
			/* Remove embedded newlines (if any) */
			char *p;
			for (p = loginmsg; *p; p++) {
				if (*p == '\n')
					*p = ' ';
			}
			/* Remove trailing newline */
			*--p = '\0';
			log("Login restricted for %s: %.100s", pw->pw_name, loginmsg);
		}
		return 0;
	}
#endif /* WITH_AIXAUTHENTICATE */

	/* We found no reason not to let this user try to log on... */
	return 1;
}

Authctxt *
authctxt_new(void)
{
	Authctxt *authctxt = xmalloc(sizeof(*authctxt));
	memset(authctxt, 0, sizeof(*authctxt));
	return authctxt;
}

void
auth_log(Authctxt *authctxt, int authenticated, char *method, char *info)
{
	void (*authlog) (const char *fmt,...) = verbose;
	char *authmsg;

	/* Raise logging level */
	if (authenticated == 1 ||
	    !authctxt->valid ||
	    authctxt->failures >= AUTH_FAIL_LOG ||
	    strcmp(method, "password") == 0)
		authlog = log;

	if (authctxt->postponed)
		authmsg = "Postponed";
	else
		authmsg = authenticated ? "Accepted" : "Failed";

	authlog("%s %s for %s%.100s from %.200s port %d%s",
	    authmsg,
	    method,
	    authctxt->valid ? "" : "illegal user ",
	    authctxt->user,
	    get_remote_ipaddr(),
	    get_remote_port(),
	    info);
}

/*
 * Check whether root logins are disallowed.
 */
int
auth_root_allowed(char *method)
{
	switch (options.permit_root_login) {
	case PERMIT_YES:
		return 1;
		break;
	case PERMIT_NO_PASSWD:
		if (strcmp(method, "password") != 0)
			return 1;
		break;
	case PERMIT_FORCED_ONLY:
		if (forced_command) {
			log("Root login accepted for forced command.");
			return 1;
		}
		break;
	}
	log("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
	return 0;
}


/*
 * Given a template and a passwd structure, build a filename
 * by substituting % tokenised options. Currently, %% becomes '%',
 * %h becomes the home directory and %u the username.
 *
 * This returns a buffer allocated by xmalloc.
 */
char *
expand_filename(const char *filename, struct passwd *pw)
{
	Buffer buffer;
	char *file;
	const char *cp;

	/*
	 * Build the filename string in the buffer by making the appropriate
	 * substitutions to the given file name.
	 */
	buffer_init(&buffer);
	for (cp = filename; *cp; cp++) {
		if (cp[0] == '%' && cp[1] == '%') {
			buffer_append(&buffer, "%", 1);
			cp++;
			continue;
		}
		if (cp[0] == '%' && cp[1] == 'h') {
			buffer_append(&buffer, pw->pw_dir, strlen(pw->pw_dir));
			cp++;
			continue;
		}
		if (cp[0] == '%' && cp[1] == 'u') {
			buffer_append(&buffer, pw->pw_name,
			    strlen(pw->pw_name));
			cp++;
			continue;
		}
		buffer_append(&buffer, cp, 1);
	}
	buffer_append(&buffer, "\0", 1);

	/*
	 * Ensure that filename starts anchored. If not, be backward
	 * compatible and prepend the '%h/'
	 */
	file = xmalloc(MAXPATHLEN);
	cp = buffer_ptr(&buffer);
	if (*cp != '/')
		snprintf(file, MAXPATHLEN, "%s/%s", pw->pw_dir, cp);
	else
		strlcpy(file, cp, MAXPATHLEN);

	buffer_free(&buffer);
	return file;
}

char *
authorized_keys_file(struct passwd *pw)
{
	return expand_filename(options.authorized_keys_file, pw);
}

char *
authorized_keys_file2(struct passwd *pw)
{
	return expand_filename(options.authorized_keys_file2, pw);
}

/* return ok if key exists in sysfile or userfile */
HostStatus
check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host,
    const char *sysfile, const char *userfile)
{
	Key *found;
	char *user_hostfile;
	struct stat st;
	HostStatus host_status;

	/* Check if we know the host and its host key. */
	found = key_new(key->type);
	host_status = check_host_in_hostfile(sysfile, host, key, found, NULL);

	if (host_status != HOST_OK && userfile != NULL) {
		user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
		if (options.strict_modes &&
		    (stat(user_hostfile, &st) == 0) &&
		    ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
		    (st.st_mode & 022) != 0)) {
			log("Authentication refused for %.100s: "
			    "bad owner or modes for %.200s",
			    pw->pw_name, user_hostfile);
		} else {
			temporarily_use_uid(pw);
			host_status = check_host_in_hostfile(user_hostfile,
			    host, key, found, NULL);
			restore_uid();
		}
		xfree(user_hostfile);
	}
	key_free(found);

	debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ?
	    "ok" : "not found", host);
	return host_status;
}


/*
 * Check a given file for security. This is defined as all components
 * of the path to the file must either be owned by either the owner of
 * of the file or root and no directories must be group or world writable.
 *
 * XXX Should any specific check be done for sym links ?
 *
 * Takes an open file descriptor, the file name, a uid and and
 * error buffer plus max size as arguments.
 *
 * Returns 0 on success and -1 on failure
 */
int
secure_filename(FILE *f, const char *file, struct passwd *pw,
    char *err, size_t errlen)
{
	uid_t uid = pw->pw_uid;
	char buf[MAXPATHLEN], homedir[MAXPATHLEN];
	char *cp;
	struct stat st;

	if (realpath(file, buf) == NULL) {
		snprintf(err, errlen, "realpath %s failed: %s", file,
		    strerror(errno));
		return -1;
	}
	if (realpath(pw->pw_dir, homedir) == NULL) {
		snprintf(err, errlen, "realpath %s failed: %s", pw->pw_dir,
		    strerror(errno));
		return -1;
	}

	/* check the open file to avoid races */
	if (fstat(fileno(f), &st) < 0 ||
	    (st.st_uid != 0 && st.st_uid != uid) ||
	    (st.st_mode & 022) != 0) {
		snprintf(err, errlen, "bad ownership or modes for file %s",
		    buf);
		return -1;
	}

	/* for each component of the canonical path, walking upwards */
	for (;;) {
		if ((cp = dirname(buf)) == NULL) {
			snprintf(err, errlen, "dirname() failed");
			return -1;
		}
		strlcpy(buf, cp, sizeof(buf));

		debug3("secure_filename: checking '%s'", buf);
		if (stat(buf, &st) < 0 ||
		    (st.st_uid != 0 && st.st_uid != uid) ||
		    (st.st_mode & 022) != 0) {
			snprintf(err, errlen,
			    "bad ownership or modes for directory %s", buf);
			return -1;
		}

		/* If are passed the homedir then we can stop */
		if (strcmp(homedir, buf) == 0) {
			debug3("secure_filename: terminating check at '%s'",
			    buf);
			break;
		}
		/*
		 * dirname should always complete with a "/" path,
		 * but we can be paranoid and check for "." too
		 */
		if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0))
			break;
	}
	return 0;
}
Commit	Line	Data
3c0ef626	1	/*
	2	* Copyright (c) 2000 Markus Friedl. All rights reserved.
	3	*
	4	* Redistribution and use in source and binary forms, with or without
	5	* modification, are permitted provided that the following conditions
	6	* are met:
	7	* 1. Redistributions of source code must retain the above copyright
	8	* notice, this list of conditions and the following disclaimer.
	9	* 2. Redistributions in binary form must reproduce the above copyright
	10	* notice, this list of conditions and the following disclaimer in the
	11	* documentation and/or other materials provided with the distribution.
	12	*
	13	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
	14	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	15	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	16	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
	17	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	18	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	19	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	20	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	21	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	22	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	23	*/
	24
	25	#include "includes.h"
e9a17296	26	RCSID("$OpenBSD: auth.c,v 1.35 2002/03/01 13:12:10 markus Exp $");
3c0ef626	27
	28	#ifdef HAVE_LOGIN_H
	29	#include <login.h>
	30	#endif
	31	#if defined(HAVE_SHADOW_H) && !defined(DISABLE_SHADOW)
	32	#include <shadow.h>
	33	#endif /* defined(HAVE_SHADOW_H) && !defined(DISABLE_SHADOW) */
	34
	35	#ifdef HAVE_LIBGEN_H
	36	#include <libgen.h>
	37	#endif
	38
	39	#include "xmalloc.h"
	40	#include "match.h"
	41	#include "groupaccess.h"
	42	#include "log.h"
	43	#include "servconf.h"
	44	#include "auth.h"
	45	#include "auth-options.h"
	46	#include "canohost.h"
	47	#include "buffer.h"
	48	#include "bufaux.h"
	49	#include "uidswap.h"
	50	#include "tildexpand.h"
	51
	52	/* import */
	53	extern ServerOptions options;
	54
	55	/*
	56	* Check if the user is allowed to log in via ssh. If user is listed
	57	* in DenyUsers or one of user's groups is listed in DenyGroups, false
	58	* will be returned. If AllowUsers isn't empty and user isn't listed
	59	* there, or if AllowGroups isn't empty and one of user's groups isn't
	60	* listed there, false will be returned.
	61	* If the user's shell is not executable, false will be returned.
	62	* Otherwise true is returned.
	63	*/
	64	int
	65	allowed_user(struct passwd * pw)
	66	{
	67	struct stat st;
	68	const char hostname = NULL, ipaddr = NULL;
	69	char *shell;
	70	int i;
	71	#ifdef WITH_AIXAUTHENTICATE
	72	char *loginmsg;
	73	#endif /* WITH_AIXAUTHENTICATE */
	74	#if !defined(USE_PAM) && defined(HAVE_SHADOW_H) && \
	75	!defined(DISABLE_SHADOW) && defined(HAS_SHADOW_EXPIRE)
	76	struct spwd *spw;
	77
	78	/* Shouldn't be called if pw is NULL, but better safe than sorry... */
	79	if (!pw \|\| !pw->pw_name)
	80	return 0;
	81
	82	spw = getspnam(pw->pw_name);
	83	if (spw != NULL) {
	84	int days = time(NULL) / 86400;
	85
	86	/* Check account expiry */
	87	if ((spw->sp_expire >= 0) && (days > spw->sp_expire))
	88	return 0;
	89
	90	/* Check password expiry */
91	if ((spw->sp_lstchg >= 0) && (spw->sp_max >= 0) &&
92	(days > (spw->sp_lstchg + spw->sp_max)))
93	return 0;
94	}
95	#else
96	/* Shouldn't be called if pw is NULL, but better safe than sorry... */
97	if (!pw \|\| !pw->pw_name)
98	return 0;
99	#endif
100
101	/*
102	* Get the shell from the password data. An empty shell field is
103	* legal, and means /bin/sh.
104	*/
105	shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;
106
107	/* deny if shell does not exists or is not executable */
e9a17296	108	if (stat(shell, &st) != 0) {
	109	log("User %.100s not allowed because shell %.100s does not exist",
	110	pw->pw_name, shell);
3c0ef626	111	return 0;
e9a17296	112	}
	113	if (!((st.st_mode & S_IFREG) && (st.st_mode & (S_IXOTH\|S_IXUSR\|S_IXGRP)))) {
	114	log("User %.100s not allowed because shell %.100s is not executable",
	115	pw->pw_name, shell);
3c0ef626	116	return 0;
e9a17296	117	}
3c0ef626	118
3c0ef626	119	if (options.num_deny_users > 0 \|\| options.num_allow_users > 0) {
e9a17296	120	hostname = get_canonical_hostname(options.verify_reverse_mapping);
3c0ef626	121	ipaddr = get_remote_ipaddr();
	122	}
	123
	124	/* Return false if user is listed in DenyUsers */
	125	if (options.num_deny_users > 0) {
	126	for (i = 0; i < options.num_deny_users; i++)
e9a17296	127	if (match_user(pw->pw_name, hostname, ipaddr,
	128	options.deny_users[i])) {
	129	log("User %.100s not allowed because listed in DenyUsers",
	130	pw->pw_name);
3c0ef626	131	return 0;
e9a17296	132	}
3c0ef626	133	}
	134	/* Return false if AllowUsers isn't empty and user isn't listed there */
	135	if (options.num_allow_users > 0) {
	136	for (i = 0; i < options.num_allow_users; i++)
e9a17296	137	if (match_user(pw->pw_name, hostname, ipaddr,
3c0ef626	138	options.allow_users[i]))
	139	break;
	140	/* i < options.num_allow_users iff we break for loop */
e9a17296	141	if (i >= options.num_allow_users) {
	142	log("User %.100s not allowed because not listed in AllowUsers",
	143	pw->pw_name);
3c0ef626	144	return 0;
e9a17296	145	}
3c0ef626	146	}
	147	if (options.num_deny_groups > 0 \|\| options.num_allow_groups > 0) {
	148	/* Get the user's group access list (primary and supplementary) */
e9a17296	149	if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
	150	log("User %.100s not allowed because not in any group",
	151	pw->pw_name);
3c0ef626	152	return 0;
e9a17296	153	}
3c0ef626	154
	155	/* Return false if one of user's groups is listed in DenyGroups */
	156	if (options.num_deny_groups > 0)
	157	if (ga_match(options.deny_groups,
	158	options.num_deny_groups)) {
	159	ga_free();
e9a17296	160	log("User %.100s not allowed because a group is listed in DenyGroups",
e9a17296	161	pw->pw_name);
3c0ef626	162	return 0;
	163	}
	164	/*
	165	* Return false if AllowGroups isn't empty and one of user's groups
	166	* isn't listed there
	167	*/
	168	if (options.num_allow_groups > 0)
	169	if (!ga_match(options.allow_groups,
	170	options.num_allow_groups)) {
	171	ga_free();
e9a17296	172	log("User %.100s not allowed because none of user's groups are listed in AllowGroups",
e9a17296	173	pw->pw_name);
3c0ef626	174	return 0;
	175	}
	176	ga_free();
	177	}
	178
	179	#ifdef WITH_AIXAUTHENTICATE
	180	if (loginrestrictions(pw->pw_name, S_RLOGIN, NULL, &loginmsg) != 0) {
	181	if (loginmsg && *loginmsg) {
	182	/* Remove embedded newlines (if any) */
	183	char *p;
	184	for (p = loginmsg; *p; p++) {
	185	if (*p == '\n')
	186	*p = ' ';
	187	}
	188	/* Remove trailing newline */
	189	*--p = '\0';
	190	log("Login restricted for %s: %.100s", pw->pw_name, loginmsg);
	191	}
	192	return 0;
	193	}
	194	#endif /* WITH_AIXAUTHENTICATE */
	195
	196	/* We found no reason not to let this user try to log on... */
	197	return 1;
	198	}
	199
	200	Authctxt *
	201	authctxt_new(void)
	202	{
	203	Authctxt authctxt = xmalloc(sizeof(authctxt));
	204	memset(authctxt, 0, sizeof(*authctxt));
	205	return authctxt;
	206	}
	207
	208	void
	209	auth_log(Authctxt authctxt, int authenticated, char method, char *info)
	210	{
	211	void (authlog) (const char fmt,...) = verbose;
	212	char *authmsg;
	213
	214	/* Raise logging level */
	215	if (authenticated == 1 \|\|
	216	!authctxt->valid \|\|
	217	authctxt->failures >= AUTH_FAIL_LOG \|\|
	218	strcmp(method, "password") == 0)
	219	authlog = log;
	220
	221	if (authctxt->postponed)
	222	authmsg = "Postponed";
	223	else
	224	authmsg = authenticated ? "Accepted" : "Failed";
	225
	226	authlog("%s %s for %s%.100s from %.200s port %d%s",
	227	authmsg,
	228	method,
	229	authctxt->valid ? "" : "illegal user ",
	230	authctxt->user,
	231	get_remote_ipaddr(),
	232	get_remote_port(),
	233	info);
	234	}
	235
	236	/*
	237	* Check whether root logins are disallowed.
238	*/
239	int
240	auth_root_allowed(char *method)
241	{
242	switch (options.permit_root_login) {
243	case PERMIT_YES:
244	return 1;
245	break;
246	case PERMIT_NO_PASSWD:
247	if (strcmp(method, "password") != 0)
248	return 1;
249	break;
250	case PERMIT_FORCED_ONLY:
251	if (forced_command) {
252	log("Root login accepted for forced command.");
253	return 1;
254	}
255	break;
256	}
257	log("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
258	return 0;
259	}
260
261
262	/*
263	* Given a template and a passwd structure, build a filename
264	* by substituting % tokenised options. Currently, %% becomes '%',
265	* %h becomes the home directory and %u the username.
266	*
267	* This returns a buffer allocated by xmalloc.
268	*/
269	char *
270	expand_filename(const char filename, struct passwd pw)
271	{
272	Buffer buffer;
273	char *file;
274	const char *cp;
275
276	/*
277	* Build the filename string in the buffer by making the appropriate
278	* substitutions to the given file name.
279	*/
280	buffer_init(&buffer);
281	for (cp = filename; *cp; cp++) {
282	if (cp[0] == '%' && cp[1] == '%') {
283	buffer_append(&buffer, "%", 1);
284	cp++;
285	continue;
286	}
287	if (cp[0] == '%' && cp[1] == 'h') {
288	buffer_append(&buffer, pw->pw_dir, strlen(pw->pw_dir));
289	cp++;
290	continue;
291	}
292	if (cp[0] == '%' && cp[1] == 'u') {
293	buffer_append(&buffer, pw->pw_name,
e9a17296	294	strlen(pw->pw_name));
3c0ef626	295	cp++;
	296	continue;
	297	}
	298	buffer_append(&buffer, cp, 1);
	299	}
	300	buffer_append(&buffer, "\0", 1);
	301
	302	/*
	303	* Ensure that filename starts anchored. If not, be backward
	304	* compatible and prepend the '%h/'
	305	*/
	306	file = xmalloc(MAXPATHLEN);
	307	cp = buffer_ptr(&buffer);
	308	if (*cp != '/')
	309	snprintf(file, MAXPATHLEN, "%s/%s", pw->pw_dir, cp);
	310	else
	311	strlcpy(file, cp, MAXPATHLEN);
	312
	313	buffer_free(&buffer);
	314	return file;
	315	}
	316
	317	char *
	318	authorized_keys_file(struct passwd *pw)
	319	{
	320	return expand_filename(options.authorized_keys_file, pw);
	321	}
	322
	323	char *
	324	authorized_keys_file2(struct passwd *pw)
	325	{
	326	return expand_filename(options.authorized_keys_file2, pw);
	327	}
	328
	329	/* return ok if key exists in sysfile or userfile */
	330	HostStatus
	331	check_key_in_hostfiles(struct passwd pw, Key key, const char *host,
	332	const char sysfile, const char userfile)
	333	{
	334	Key *found;
	335	char *user_hostfile;
	336	struct stat st;
e9a17296	337	HostStatus host_status;
3c0ef626	338
	339	/* Check if we know the host and its host key. */
	340	found = key_new(key->type);
	341	host_status = check_host_in_hostfile(sysfile, host, key, found, NULL);
	342
	343	if (host_status != HOST_OK && userfile != NULL) {
	344	user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
	345	if (options.strict_modes &&
	346	(stat(user_hostfile, &st) == 0) &&
	347	((st.st_uid != 0 && st.st_uid != pw->pw_uid) \|\|
e9a17296	348	(st.st_mode & 022) != 0)) {
3c0ef626	349	log("Authentication refused for %.100s: "
	350	"bad owner or modes for %.200s",
	351	pw->pw_name, user_hostfile);
	352	} else {
	353	temporarily_use_uid(pw);
	354	host_status = check_host_in_hostfile(user_hostfile,
	355	host, key, found, NULL);
	356	restore_uid();
	357	}
	358	xfree(user_hostfile);
	359	}
	360	key_free(found);
	361
	362	debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ?
	363	"ok" : "not found", host);
	364	return host_status;
	365	}
	366
	367
	368	/*
	369	* Check a given file for security. This is defined as all components
	370	* of the path to the file must either be owned by either the owner of
	371	* of the file or root and no directories must be group or world writable.
	372	*
	373	* XXX Should any specific check be done for sym links ?
	374	*
	375	* Takes an open file descriptor, the file name, a uid and and
	376	* error buffer plus max size as arguments.
	377	*
	378	* Returns 0 on success and -1 on failure
	379	*/
	380	int
	381	secure_filename(FILE f, const char file, struct passwd *pw,
	382	char *err, size_t errlen)
	383	{
	384	uid_t uid = pw->pw_uid;
	385	char buf[MAXPATHLEN], homedir[MAXPATHLEN];
	386	char *cp;
	387	struct stat st;
	388
	389	if (realpath(file, buf) == NULL) {
	390	snprintf(err, errlen, "realpath %s failed: %s", file,
	391	strerror(errno));
	392	return -1;
	393	}
	394	if (realpath(pw->pw_dir, homedir) == NULL) {
	395	snprintf(err, errlen, "realpath %s failed: %s", pw->pw_dir,
	396	strerror(errno));
	397	return -1;
	398	}
	399
	400	/* check the open file to avoid races */
	401	if (fstat(fileno(f), &st) < 0 \|\|
	402	(st.st_uid != 0 && st.st_uid != uid) \|\|
	403	(st.st_mode & 022) != 0) {
	404	snprintf(err, errlen, "bad ownership or modes for file %s",
	405	buf);
	406	return -1;
	407	}
	408
	409	/* for each component of the canonical path, walking upwards */
	410	for (;;) {
	411	if ((cp = dirname(buf)) == NULL) {
	412	snprintf(err, errlen, "dirname() failed");
413	return -1;
414	}
415	strlcpy(buf, cp, sizeof(buf));
416
417	debug3("secure_filename: checking '%s'", buf);
418	if (stat(buf, &st) < 0 \|\|
419	(st.st_uid != 0 && st.st_uid != uid) \|\|
420	(st.st_mode & 022) != 0) {
e9a17296	421	snprintf(err, errlen,
3c0ef626	422	"bad ownership or modes for directory %s", buf);
	423	return -1;
	424	}
	425
	426	/* If are passed the homedir then we can stop */
	427	if (strcmp(homedir, buf) == 0) {
	428	debug3("secure_filename: terminating check at '%s'",
	429	buf);
	430	break;
	431	}
	432	/*
	433	* dirname should always complete with a "/" path,
	434	* but we can be paranoid and check for "." too
	435	*/
	436	if ((strcmp("/", buf) == 0) \|\| (strcmp(".", buf) == 0))
	437	break;
	438	}
	439	return 0;
	440	}