[openssh.git] / 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 1.29 2001/11/08 20:02:24 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)
		return 0;
	if (!((st.st_mode & S_IFREG) && (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP))))
		return 0;

	if (options.num_deny_users > 0 || options.num_allow_users > 0) {
		hostname = get_canonical_hostname(options.reverse_mapping_check);
		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]))
				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)
			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)
			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();
				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();
				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;
	int 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
7368a6c8	1	/*
f3c7c613	2	* Copyright (c) 2000 Markus Friedl. All rights reserved.
bcbf86ec	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.
7368a6c8	23	*/
	24
	25	#include "includes.h"
fad3754c	26	RCSID("$OpenBSD: auth.c,v 1.29 2001/11/08 20:02:24 markus Exp $");
7368a6c8	27
c1ef8333	28	#ifdef HAVE_LOGIN_H
	29	#include <login.h>
	30	#endif
4cb5ffa0	31	#if defined(HAVE_SHADOW_H) && !defined(DISABLE_SHADOW)
	32	#include <shadow.h>
	33	#endif /* defined(HAVE_SHADOW_H) && !defined(DISABLE_SHADOW) */
7368a6c8	34
b4d02860	35	#ifdef HAVE_LIBGEN_H
c8445989	36	#include <libgen.h>
b4d02860	37	#endif
c8445989	38
42f11eb2	39	#include "xmalloc.h"
	40	#include "match.h"
	41	#include "groupaccess.h"
	42	#include "log.h"
	43	#include "servconf.h"
e78a59f5	44	#include "auth.h"
59c97189	45	#include "auth-options.h"
42f11eb2	46	#include "canohost.h"
c8445989	47	#include "buffer.h"
c8445989	48	#include "bufaux.h"
d0c8ca5c	49	#include "uidswap.h"
d0c8ca5c	50	#include "tildexpand.h"
e78a59f5	51
7368a6c8	52	/* import */
7368a6c8	53	extern ServerOptions options;
7368a6c8	54
7368a6c8	55	/*
c6a69271	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.
7368a6c8	61	* If the user's shell is not executable, false will be returned.
6ae2364d	62	* Otherwise true is returned.
7368a6c8	63	*/
a306f2dd	64	int
7368a6c8	65	allowed_user(struct passwd * pw)
	66	{
	67	struct stat st;
80f8f24f	68	const char hostname = NULL, ipaddr = NULL;
614dee3a	69	char *shell;
7368a6c8	70	int i;
	71	#ifdef WITH_AIXAUTHENTICATE
	72	char *loginmsg;
	73	#endif /* WITH_AIXAUTHENTICATE */
75b90ced	74	#if !defined(USE_PAM) && defined(HAVE_SHADOW_H) && \
37c1c46d	75	!defined(DISABLE_SHADOW) && defined(HAS_SHADOW_EXPIRE)
c6a69271	76	struct spwd *spw;
7368a6c8	77
7368a6c8	78	/* Shouldn't be called if pw is NULL, but better safe than sorry... */
c6a69271	79	if (!pw \|\| !pw->pw_name)
7368a6c8	80	return 0;
7368a6c8	81
4cb5ffa0	82	spw = getspnam(pw->pw_name);
27494968	83	if (spw != NULL) {
27494968	84	int days = time(NULL) / 86400;
4cb5ffa0	85
27494968	86	/* Check account expiry */
37c1c46d	87	if ((spw->sp_expire >= 0) && (days > spw->sp_expire))
27494968	88	return 0;
	89
	90	/* Check password expiry */
2b87da3b	91	if ((spw->sp_lstchg >= 0) && (spw->sp_max >= 0) &&
7f8f5e00	92	(days > (spw->sp_lstchg + spw->sp_max)))
27494968	93	return 0;
27494968	94	}
4cb5ffa0	95	#else
4cb5ffa0	96	/* Shouldn't be called if pw is NULL, but better safe than sorry... */
c6a69271	97	if (!pw \|\| !pw->pw_name)
4cb5ffa0	98	return 0;
	99	#endif
	100
301e9b01	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 */
	108	if (stat(shell, &st) != 0)
7368a6c8	109	return 0;
	110	if (!((st.st_mode & S_IFREG) && (st.st_mode & (S_IXOTH\|S_IXUSR\|S_IXGRP))))
	111	return 0;
	112
80f8f24f	113	if (options.num_deny_users > 0 \|\| options.num_allow_users > 0) {
	114	hostname = get_canonical_hostname(options.reverse_mapping_check);
	115	ipaddr = get_remote_ipaddr();
	116	}
	117
7368a6c8	118	/* Return false if user is listed in DenyUsers */
7368a6c8	119	if (options.num_deny_users > 0) {
7368a6c8	120	for (i = 0; i < options.num_deny_users; i++)
80f8f24f	121	if (match_user(pw->pw_name, hostname, ipaddr,
80f8f24f	122	options.deny_users[i]))
7368a6c8	123	return 0;
	124	}
	125	/* Return false if AllowUsers isn't empty and user isn't listed there */
	126	if (options.num_allow_users > 0) {
7368a6c8	127	for (i = 0; i < options.num_allow_users; i++)
80f8f24f	128	if (match_user(pw->pw_name, hostname, ipaddr,
80f8f24f	129	options.allow_users[i]))
7368a6c8	130	break;
	131	/* i < options.num_allow_users iff we break for loop */
	132	if (i >= options.num_allow_users)
	133	return 0;
	134	}
7368a6c8	135	if (options.num_deny_groups > 0 \|\| options.num_allow_groups > 0) {
c6a69271	136	/* Get the user's group access list (primary and supplementary) */
c6a69271	137	if (ga_init(pw->pw_name, pw->pw_gid) == 0)
7368a6c8	138	return 0;
7368a6c8	139
c6a69271	140	/* Return false if one of user's groups is listed in DenyGroups */
	141	if (options.num_deny_groups > 0)
	142	if (ga_match(options.deny_groups,
	143	options.num_deny_groups)) {
	144	ga_free();
7368a6c8	145	return 0;
c6a69271	146	}
7368a6c8	147	/*
c6a69271	148	* Return false if AllowGroups isn't empty and one of user's groups
7368a6c8	149	* isn't listed there
7368a6c8	150	*/
c6a69271	151	if (options.num_allow_groups > 0)
	152	if (!ga_match(options.allow_groups,
	153	options.num_allow_groups)) {
	154	ga_free();
7368a6c8	155	return 0;
c6a69271	156	}
c6a69271	157	ga_free();
7368a6c8	158	}
	159
	160	#ifdef WITH_AIXAUTHENTICATE
5daf7064	161	if (loginrestrictions(pw->pw_name, S_RLOGIN, NULL, &loginmsg) != 0) {
c1ef8333	162	if (loginmsg && *loginmsg) {
	163	/* Remove embedded newlines (if any) */
	164	char *p;
5daf7064	165	for (p = loginmsg; *p; p++) {
c1ef8333	166	if (*p == '\n')
c1ef8333	167	*p = ' ';
5daf7064	168	}
c1ef8333	169	/* Remove trailing newline */
c1ef8333	170	*--p = '\0';
5daf7064	171	log("Login restricted for %s: %.100s", pw->pw_name, loginmsg);
c1ef8333	172	}
7368a6c8	173	return 0;
c1ef8333	174	}
7368a6c8	175	#endif /* WITH_AIXAUTHENTICATE */
	176
	177	/* We found no reason not to let this user try to log on... */
	178	return 1;
	179	}
59c97189	180
	181	Authctxt *
	182	authctxt_new(void)
	183	{
2b87da3b	184	Authctxt authctxt = xmalloc(sizeof(authctxt));
	185	memset(authctxt, 0, sizeof(*authctxt));
	186	return authctxt;
59c97189	187	}
59c97189	188
59c97189	189	void
	190	auth_log(Authctxt authctxt, int authenticated, char method, char *info)
	191	{
	192	void (authlog) (const char fmt,...) = verbose;
	193	char *authmsg;
	194
	195	/* Raise logging level */
	196	if (authenticated == 1 \|\|
	197	!authctxt->valid \|\|
	198	authctxt->failures >= AUTH_FAIL_LOG \|\|
	199	strcmp(method, "password") == 0)
	200	authlog = log;
	201
	202	if (authctxt->postponed)
	203	authmsg = "Postponed";
	204	else
	205	authmsg = authenticated ? "Accepted" : "Failed";
	206
	207	authlog("%s %s for %s%.100s from %.200s port %d%s",
	208	authmsg,
	209	method,
	210	authctxt->valid ? "" : "illegal user ",
fad3754c	211	authctxt->user,
59c97189	212	get_remote_ipaddr(),
	213	get_remote_port(),
	214	info);
	215	}
	216
	217	/*
15853e93	218	* Check whether root logins are disallowed.
59c97189	219	*/
59c97189	220	int
15853e93	221	auth_root_allowed(char *method)
59c97189	222	{
15853e93	223	switch (options.permit_root_login) {
15853e93	224	case PERMIT_YES:
59c97189	225	return 1;
15853e93	226	break;
	227	case PERMIT_NO_PASSWD:
	228	if (strcmp(method, "password") != 0)
	229	return 1;
	230	break;
	231	case PERMIT_FORCED_ONLY:
	232	if (forced_command) {
	233	log("Root login accepted for forced command.");
	234	return 1;
	235	}
	236	break;
59c97189	237	}
15853e93	238	log("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
15853e93	239	return 0;
59c97189	240	}
c8445989	241
	242
	243	/*
	244	* Given a template and a passwd structure, build a filename
	245	* by substituting % tokenised options. Currently, %% becomes '%',
	246	* %h becomes the home directory and %u the username.
	247	*
	248	* This returns a buffer allocated by xmalloc.
	249	*/
	250	char *
	251	expand_filename(const char filename, struct passwd pw)
	252	{
	253	Buffer buffer;
	254	char *file;
	255	const char *cp;
	256
	257	/*
	258	* Build the filename string in the buffer by making the appropriate
	259	* substitutions to the given file name.
	260	*/
	261	buffer_init(&buffer);
	262	for (cp = filename; *cp; cp++) {
	263	if (cp[0] == '%' && cp[1] == '%') {
	264	buffer_append(&buffer, "%", 1);
	265	cp++;
	266	continue;
	267	}
	268	if (cp[0] == '%' && cp[1] == 'h') {
	269	buffer_append(&buffer, pw->pw_dir, strlen(pw->pw_dir));
	270	cp++;
	271	continue;
	272	}
	273	if (cp[0] == '%' && cp[1] == 'u') {
	274	buffer_append(&buffer, pw->pw_name,
	275	strlen(pw->pw_name));
	276	cp++;
	277	continue;
	278	}
	279	buffer_append(&buffer, cp, 1);
	280	}
	281	buffer_append(&buffer, "\0", 1);
	282
	283	/*
	284	* Ensure that filename starts anchored. If not, be backward
	285	* compatible and prepend the '%h/'
	286	*/
	287	file = xmalloc(MAXPATHLEN);
	288	cp = buffer_ptr(&buffer);
	289	if (*cp != '/')
	290	snprintf(file, MAXPATHLEN, "%s/%s", pw->pw_dir, cp);
	291	else
	292	strlcpy(file, cp, MAXPATHLEN);
	293
	294	buffer_free(&buffer);
	295	return file;
	296	}
	297
	298	char *
	299	authorized_keys_file(struct passwd *pw)
	300	{
	301	return expand_filename(options.authorized_keys_file, pw);
	302	}
	303
	304	char *
305	authorized_keys_file2(struct passwd *pw)
306	{
307	return expand_filename(options.authorized_keys_file2, pw);
308	}
309
d0c8ca5c	310	/* return ok if key exists in sysfile or userfile */
	311	HostStatus
	312	check_key_in_hostfiles(struct passwd pw, Key key, const char *host,
	313	const char sysfile, const char userfile)
	314	{
	315	Key *found;
	316	char *user_hostfile;
	317	struct stat st;
	318	int host_status;
	319
	320	/* Check if we know the host and its host key. */
	321	found = key_new(key->type);
	322	host_status = check_host_in_hostfile(sysfile, host, key, found, NULL);
	323
	324	if (host_status != HOST_OK && userfile != NULL) {
	325	user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
	326	if (options.strict_modes &&
	327	(stat(user_hostfile, &st) == 0) &&
	328	((st.st_uid != 0 && st.st_uid != pw->pw_uid) \|\|
	329	(st.st_mode & 022) != 0)) {
	330	log("Authentication refused for %.100s: "
	331	"bad owner or modes for %.200s",
	332	pw->pw_name, user_hostfile);
	333	} else {
	334	temporarily_use_uid(pw);
	335	host_status = check_host_in_hostfile(user_hostfile,
	336	host, key, found, NULL);
	337	restore_uid();
	338	}
	339	xfree(user_hostfile);
	340	}
	341	key_free(found);
	342
	343	debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ?
	344	"ok" : "not found", host);
	345	return host_status;
	346	}
	347
	348
c8445989	349	/*
	350	* Check a given file for security. This is defined as all components
	351	* of the path to the file must either be owned by either the owner of
1ddf764b	352	* of the file or root and no directories must be group or world writable.
c8445989	353	*
	354	* XXX Should any specific check be done for sym links ?
	355	*
	356	* Takes an open file descriptor, the file name, a uid and and
	357	* error buffer plus max size as arguments.
	358	*
	359	* Returns 0 on success and -1 on failure
	360	*/
	361	int
6978866a	362	secure_filename(FILE f, const char file, struct passwd *pw,
6978866a	363	char *err, size_t errlen)
c8445989	364	{
6978866a	365	uid_t uid = pw->pw_uid;
76fbdd47	366	char buf[MAXPATHLEN], homedir[MAXPATHLEN];
c8445989	367	char *cp;
	368	struct stat st;
	369
	370	if (realpath(file, buf) == NULL) {
	371	snprintf(err, errlen, "realpath %s failed: %s", file,
	372	strerror(errno));
	373	return -1;
	374	}
76fbdd47	375	if (realpath(pw->pw_dir, homedir) == NULL) {
	376	snprintf(err, errlen, "realpath %s failed: %s", pw->pw_dir,
	377	strerror(errno));
	378	return -1;
	379	}
c8445989	380
	381	/* check the open file to avoid races */
	382	if (fstat(fileno(f), &st) < 0 \|\|
	383	(st.st_uid != 0 && st.st_uid != uid) \|\|
	384	(st.st_mode & 022) != 0) {
	385	snprintf(err, errlen, "bad ownership or modes for file %s",
	386	buf);
	387	return -1;
	388	}
	389
	390	/* for each component of the canonical path, walking upwards */
	391	for (;;) {
	392	if ((cp = dirname(buf)) == NULL) {
	393	snprintf(err, errlen, "dirname() failed");
	394	return -1;
	395	}
	396	strlcpy(buf, cp, sizeof(buf));
	397
	398	debug3("secure_filename: checking '%s'", buf);
	399	if (stat(buf, &st) < 0 \|\|
	400	(st.st_uid != 0 && st.st_uid != uid) \|\|
	401	(st.st_mode & 022) != 0) {
	402	snprintf(err, errlen,
	403	"bad ownership or modes for directory %s", buf);
	404	return -1;
	405	}
	406
afd501f9	407	/* If are passed the homedir then we can stop */
76fbdd47	408	if (strcmp(homedir, buf) == 0) {
afd501f9	409	debug3("secure_filename: terminating check at '%s'",
	410	buf);
	411	break;
	412	}
c8445989	413	/*
	414	* dirname should always complete with a "/" path,
	415	* but we can be paranoid and check for "." too
	416	*/
	417	if ((strcmp("/", buf) == 0) \|\| (strcmp(".", buf) == 0))
	418	break;
	419	}
	420	return 0;
	421	}