[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 1.56 2004/07/28 09:40:29 markus Exp $");

#ifdef HAVE_LOGIN_H
#include <login.h>
#endif
#ifdef USE_SHADOW
#include <shadow.h>
#endif

#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 "misc.h"
#include "bufaux.h"
#include "packet.h"

/* import */
extern ServerOptions options;
extern Buffer loginmsg;

/* Debugging messages */
Buffer auth_debug;
int auth_debug_init;

/*
 * 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, *passwd = NULL;
	char *shell;
	int i;
#ifdef USE_SHADOW
	struct spwd *spw = NULL;
#endif

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

#ifdef USE_SHADOW
	if (!options.use_pam)
		spw = getspnam(pw->pw_name);
#ifdef HAS_SHADOW_EXPIRE
	if (!options.use_pam && spw != NULL && auth_shadow_acctexpired(spw))
		return 0;
#endif /* HAS_SHADOW_EXPIRE */
#endif /* USE_SHADOW */

	/* grab passwd field for locked account check */
#ifdef USE_SHADOW
	if (spw != NULL)
		passwd = spw->sp_pwdp;
#else
	passwd = pw->pw_passwd;
#endif

	/* check for locked account */
	if (!options.use_pam && passwd && *passwd) {
		int locked = 0;

#ifdef LOCKED_PASSWD_STRING
		if (strcmp(passwd, LOCKED_PASSWD_STRING) == 0)
			 locked = 1;
#endif
#ifdef LOCKED_PASSWD_PREFIX
		if (strncmp(passwd, LOCKED_PASSWD_PREFIX,
		    strlen(LOCKED_PASSWD_PREFIX)) == 0)
			 locked = 1;
#endif
#ifdef LOCKED_PASSWD_SUBSTR
		if (strstr(passwd, LOCKED_PASSWD_SUBSTR))
			locked = 1;
#endif
		if (locked) {
			logit("User %.100s not allowed because account is locked",
			    pw->pw_name);
			return 0;
		}
	}

	/*
	 * 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) {
		logit("User %.100s not allowed because shell %.100s does not exist",
		    pw->pw_name, shell);
		return 0;
	}
	if (S_ISREG(st.st_mode) == 0 ||
	    (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) {
		logit("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.use_dns);
		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])) {
				logit("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) {
			logit("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) {
			logit("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();
				logit("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();
				logit("User %.100s not allowed because none of user's groups are listed in AllowGroups",
				    pw->pw_name);
				return 0;
			}
		ga_free();
	}

#ifdef CUSTOM_SYS_AUTH_ALLOWED_USER
	if (!sys_auth_allowed_user(pw))
		return 0;
#endif

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

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 >= options.max_authtries / 2 ||
	    strcmp(method, "password") == 0)
		authlog = logit;

	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 ? "" : "invalid user ",
	    (authctxt->user && authctxt->user[0]) ?
		authctxt->user : "<implicit>",
	    get_remote_ipaddr(),
	    get_remote_port(),
	    info);

#ifdef CUSTOM_FAILED_LOGIN
	if (authenticated == 0 && strcmp(method, "password") == 0)
		record_failed_login(authctxt->user, "ssh");
#endif
}

/*
 * 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) {
			logit("Root login accepted for forced command.");
			return 1;
		}
		break;
	}
	logit("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)) {
			logit("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 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;
	int comparehome = 0;
	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)
		comparehome = 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 (comparehome && 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;
}

struct passwd *
getpwnamallow(const char *user)
{
#ifdef HAVE_LOGIN_CAP
	extern login_cap_t *lc;
#ifdef BSD_AUTH
	auth_session_t *as;
#endif
#endif
	struct passwd *pw;

	pw = getpwnam(user);
	if (pw == NULL) {
		logit("Invalid user %.100s from %.100s",
		      (user && user[0]) ? user : "<implicit>",
		      get_remote_ipaddr());
#ifdef CUSTOM_FAILED_LOGIN
		record_failed_login(user, "ssh");
#endif
		return (NULL);
	}
	if (!allowed_user(pw))
		return (NULL);
#ifdef HAVE_LOGIN_CAP
	if ((lc = login_getclass(pw->pw_class)) == NULL) {
		debug("unable to get login class: %s", user);
		return (NULL);
	}
#ifdef BSD_AUTH
	if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 ||
	    auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
		debug("Approval failure for %s", user);
		pw = NULL;
	}
	if (as != NULL)
		auth_close(as);
#endif
#endif
	if (pw != NULL)
		return (pwcopy(pw));
	return (NULL);
}

void
auth_debug_add(const char *fmt,...)
{
	char buf[1024];
	va_list args;

	if (!auth_debug_init)
		return;

	va_start(args, fmt);
	vsnprintf(buf, sizeof(buf), fmt, args);
	va_end(args);
	buffer_put_cstring(&auth_debug, buf);
}

void
auth_debug_send(void)
{
	char *msg;

	if (!auth_debug_init)
		return;
	while (buffer_len(&auth_debug)) {
		msg = buffer_get_string(&auth_debug, NULL);
		packet_send_debug("%s", msg);
		xfree(msg);
	}
}

void
auth_debug_reset(void)
{
	if (auth_debug_init)
		buffer_clear(&auth_debug);
	else {
		buffer_init(&auth_debug);
		auth_debug_init = 1;
	}
}

struct passwd *
fakepw(void)
{
	static struct passwd fake;

	memset(&fake, 0, sizeof(fake));
	fake.pw_name = "NOUSER";
	fake.pw_passwd =
	    "$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK";
	fake.pw_gecos = "NOUSER";
	fake.pw_uid = (uid_t)-1;
	fake.pw_gid = (gid_t)-1;
#ifdef HAVE_PW_CLASS_IN_PASSWD
	fake.pw_class = "";
#endif
	fake.pw_dir = "/nonexist";
	fake.pw_shell = "/nonexist";

	return (&fake);
}
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"
1b56ff3d	26	RCSID("$OpenBSD: auth.c,v 1.56 2004/07/28 09:40:29 markus Exp $");
3c0ef626	27
	28	#ifdef HAVE_LOGIN_H
	29	#include <login.h>
	30	#endif
416fd2a8	31	#ifdef USE_SHADOW
3c0ef626	32	#include <shadow.h>
416fd2a8	33	#endif
3c0ef626	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"
2980ea68	50	#include "misc.h"
	51	#include "bufaux.h"
	52	#include "packet.h"
3c0ef626	53
	54	/* import */
	55	extern ServerOptions options;
70791e56	56	extern Buffer loginmsg;
3c0ef626	57
2980ea68	58	/* Debugging messages */
	59	Buffer auth_debug;
	60	int auth_debug_init;
	61
3c0ef626	62	/*
	63	* Check if the user is allowed to log in via ssh. If user is listed
	64	* in DenyUsers or one of user's groups is listed in DenyGroups, false
	65	* will be returned. If AllowUsers isn't empty and user isn't listed
	66	* there, or if AllowGroups isn't empty and one of user's groups isn't
	67	* listed there, false will be returned.
	68	* If the user's shell is not executable, false will be returned.
	69	* Otherwise true is returned.
	70	*/
	71	int
	72	allowed_user(struct passwd * pw)
	73	{
	74	struct stat st;
70791e56	75	const char hostname = NULL, ipaddr = NULL, *passwd = NULL;
3c0ef626	76	char *shell;
3c0ef626	77	int i;
416fd2a8	78	#ifdef USE_SHADOW
70791e56	79	struct spwd *spw = NULL;
1c14df9e	80	#endif
3c0ef626	81
	82	/* Shouldn't be called if pw is NULL, but better safe than sorry... */
	83	if (!pw \|\| !pw->pw_name)
	84	return 0;
	85
416fd2a8	86	#ifdef USE_SHADOW
70791e56	87	if (!options.use_pam)
	88	spw = getspnam(pw->pw_name);
	89	#ifdef HAS_SHADOW_EXPIRE
416fd2a8	90	if (!options.use_pam && spw != NULL && auth_shadow_acctexpired(spw))
416fd2a8	91	return 0;
70791e56	92	#endif /* HAS_SHADOW_EXPIRE */
416fd2a8	93	#endif /* USE_SHADOW */
70791e56	94
416fd2a8	95	/* grab passwd field for locked account check */
416fd2a8	96	#ifdef USE_SHADOW
70791e56	97	if (spw != NULL)
	98	passwd = spw->sp_pwdp;
	99	#else
	100	passwd = pw->pw_passwd;
3c0ef626	101	#endif
3c0ef626	102
416fd2a8	103	/* check for locked account */
70791e56	104	if (!options.use_pam && passwd && *passwd) {
	105	int locked = 0;
	106
	107	#ifdef LOCKED_PASSWD_STRING
	108	if (strcmp(passwd, LOCKED_PASSWD_STRING) == 0)
	109	locked = 1;
	110	#endif
	111	#ifdef LOCKED_PASSWD_PREFIX
	112	if (strncmp(passwd, LOCKED_PASSWD_PREFIX,
	113	strlen(LOCKED_PASSWD_PREFIX)) == 0)
	114	locked = 1;
	115	#endif
	116	#ifdef LOCKED_PASSWD_SUBSTR
	117	if (strstr(passwd, LOCKED_PASSWD_SUBSTR))
	118	locked = 1;
	119	#endif
	120	if (locked) {
	121	logit("User %.100s not allowed because account is locked",
	122	pw->pw_name);
	123	return 0;
	124	}
	125	}
	126
3c0ef626	127	/*
	128	* Get the shell from the password data. An empty shell field is
	129	* legal, and means /bin/sh.
	130	*/
	131	shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;
	132
	133	/* deny if shell does not exists or is not executable */
e9a17296	134	if (stat(shell, &st) != 0) {
70791e56	135	logit("User %.100s not allowed because shell %.100s does not exist",
e9a17296	136	pw->pw_name, shell);
3c0ef626	137	return 0;
e9a17296	138	}
2980ea68	139	if (S_ISREG(st.st_mode) == 0 \|\|
2980ea68	140	(st.st_mode & (S_IXOTH\|S_IXUSR\|S_IXGRP)) == 0) {
70791e56	141	logit("User %.100s not allowed because shell %.100s is not executable",
e9a17296	142	pw->pw_name, shell);
3c0ef626	143	return 0;
e9a17296	144	}
3c0ef626	145
3c0ef626	146	if (options.num_deny_users > 0 \|\| options.num_allow_users > 0) {
70791e56	147	hostname = get_canonical_hostname(options.use_dns);
3c0ef626	148	ipaddr = get_remote_ipaddr();
	149	}
	150
	151	/* Return false if user is listed in DenyUsers */
	152	if (options.num_deny_users > 0) {
	153	for (i = 0; i < options.num_deny_users; i++)
2980ea68	154	if (match_user(pw->pw_name, hostname, ipaddr,
e9a17296	155	options.deny_users[i])) {
70791e56	156	logit("User %.100s not allowed because listed in DenyUsers",
2980ea68	157	pw->pw_name);
3c0ef626	158	return 0;
e9a17296	159	}
3c0ef626	160	}
	161	/* Return false if AllowUsers isn't empty and user isn't listed there */
	162	if (options.num_allow_users > 0) {
	163	for (i = 0; i < options.num_allow_users; i++)
078f71c2	164	if (match_user(pw->pw_name, hostname, ipaddr,
3c0ef626	165	options.allow_users[i]))
	166	break;
	167	/* i < options.num_allow_users iff we break for loop */
e9a17296	168	if (i >= options.num_allow_users) {
70791e56	169	logit("User %.100s not allowed because not listed in AllowUsers",
e9a17296	170	pw->pw_name);
3c0ef626	171	return 0;
e9a17296	172	}
3c0ef626	173	}
	174	if (options.num_deny_groups > 0 \|\| options.num_allow_groups > 0) {
	175	/* Get the user's group access list (primary and supplementary) */
e9a17296	176	if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
70791e56	177	logit("User %.100s not allowed because not in any group",
e9a17296	178	pw->pw_name);
3c0ef626	179	return 0;
e9a17296	180	}
3c0ef626	181
	182	/* Return false if one of user's groups is listed in DenyGroups */
	183	if (options.num_deny_groups > 0)
	184	if (ga_match(options.deny_groups,
	185	options.num_deny_groups)) {
	186	ga_free();
70791e56	187	logit("User %.100s not allowed because a group is listed in DenyGroups",
e9a17296	188	pw->pw_name);
3c0ef626	189	return 0;
	190	}
	191	/*
	192	* Return false if AllowGroups isn't empty and one of user's groups
	193	* isn't listed there
	194	*/
	195	if (options.num_allow_groups > 0)
	196	if (!ga_match(options.allow_groups,
	197	options.num_allow_groups)) {
	198	ga_free();
70791e56	199	logit("User %.100s not allowed because none of user's groups are listed in AllowGroups",
e9a17296	200	pw->pw_name);
3c0ef626	201	return 0;
	202	}
	203	ga_free();
	204	}
	205
1b56ff3d	206	#ifdef CUSTOM_SYS_AUTH_ALLOWED_USER
	207	if (!sys_auth_allowed_user(pw))
	208	return 0;
	209	#endif
3c0ef626	210
	211	/* We found no reason not to let this user try to log on... */
	212	return 1;
	213	}
	214
3c0ef626	215	void
	216	auth_log(Authctxt authctxt, int authenticated, char method, char *info)
	217	{
	218	void (authlog) (const char fmt,...) = verbose;
	219	char *authmsg;
	220
	221	/* Raise logging level */
	222	if (authenticated == 1 \|\|
	223	!authctxt->valid \|\|
1b56ff3d	224	authctxt->failures >= options.max_authtries / 2 \|\|
3c0ef626	225	strcmp(method, "password") == 0)
70791e56	226	authlog = logit;
3c0ef626	227
	228	if (authctxt->postponed)
	229	authmsg = "Postponed";
	230	else
	231	authmsg = authenticated ? "Accepted" : "Failed";
	232
	233	authlog("%s %s for %s%.100s from %.200s port %d%s",
	234	authmsg,
	235	method,
1b56ff3d	236	authctxt->valid ? "" : "invalid user ",
	237	(authctxt->user && authctxt->user[0]) ?
	238	authctxt->user : "<implicit>",
3c0ef626	239	get_remote_ipaddr(),
	240	get_remote_port(),
	241	info);
e54b3d7c	242
70791e56	243	#ifdef CUSTOM_FAILED_LOGIN
e54b3d7c	244	if (authenticated == 0 && strcmp(method, "password") == 0)
70791e56	245	record_failed_login(authctxt->user, "ssh");
70791e56	246	#endif
3c0ef626	247	}
	248
	249	/*
	250	* Check whether root logins are disallowed.
	251	*/
	252	int
	253	auth_root_allowed(char *method)
	254	{
	255	switch (options.permit_root_login) {
	256	case PERMIT_YES:
	257	return 1;
	258	break;
	259	case PERMIT_NO_PASSWD:
	260	if (strcmp(method, "password") != 0)
	261	return 1;
	262	break;
	263	case PERMIT_FORCED_ONLY:
	264	if (forced_command) {
70791e56	265	logit("Root login accepted for forced command.");
3c0ef626	266	return 1;
	267	}
	268	break;
	269	}
70791e56	270	logit("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
3c0ef626	271	return 0;
	272	}
	273
	274
	275	/*
	276	* Given a template and a passwd structure, build a filename
	277	* by substituting % tokenised options. Currently, %% becomes '%',
	278	* %h becomes the home directory and %u the username.
	279	*
	280	* This returns a buffer allocated by xmalloc.
	281	*/
	282	char *
	283	expand_filename(const char filename, struct passwd pw)
	284	{
	285	Buffer buffer;
	286	char *file;
	287	const char *cp;
	288
	289	/*
	290	* Build the filename string in the buffer by making the appropriate
	291	* substitutions to the given file name.
	292	*/
	293	buffer_init(&buffer);
	294	for (cp = filename; *cp; cp++) {
	295	if (cp[0] == '%' && cp[1] == '%') {
	296	buffer_append(&buffer, "%", 1);
	297	cp++;
	298	continue;
	299	}
	300	if (cp[0] == '%' && cp[1] == 'h') {
	301	buffer_append(&buffer, pw->pw_dir, strlen(pw->pw_dir));
	302	cp++;
	303	continue;
	304	}
	305	if (cp[0] == '%' && cp[1] == 'u') {
	306	buffer_append(&buffer, pw->pw_name,
e9a17296	307	strlen(pw->pw_name));
3c0ef626	308	cp++;
	309	continue;
	310	}
	311	buffer_append(&buffer, cp, 1);
	312	}
	313	buffer_append(&buffer, "\0", 1);
	314
	315	/*
	316	* Ensure that filename starts anchored. If not, be backward
	317	* compatible and prepend the '%h/'
	318	*/
	319	file = xmalloc(MAXPATHLEN);
	320	cp = buffer_ptr(&buffer);
	321	if (*cp != '/')
	322	snprintf(file, MAXPATHLEN, "%s/%s", pw->pw_dir, cp);
	323	else
	324	strlcpy(file, cp, MAXPATHLEN);
	325
	326	buffer_free(&buffer);
	327	return file;
	328	}
	329
	330	char *
	331	authorized_keys_file(struct passwd *pw)
	332	{
	333	return expand_filename(options.authorized_keys_file, pw);
	334	}
	335
	336	char *
	337	authorized_keys_file2(struct passwd *pw)
	338	{
	339	return expand_filename(options.authorized_keys_file2, pw);
	340	}
	341
	342	/* return ok if key exists in sysfile or userfile */
	343	HostStatus
	344	check_key_in_hostfiles(struct passwd pw, Key key, const char *host,
	345	const char sysfile, const char userfile)
	346	{
	347	Key *found;
	348	char *user_hostfile;
	349	struct stat st;
e9a17296	350	HostStatus host_status;
3c0ef626	351
	352	/* Check if we know the host and its host key. */
	353	found = key_new(key->type);
	354	host_status = check_host_in_hostfile(sysfile, host, key, found, NULL);
	355
	356	if (host_status != HOST_OK && userfile != NULL) {
	357	user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
	358	if (options.strict_modes &&
	359	(stat(user_hostfile, &st) == 0) &&
	360	((st.st_uid != 0 && st.st_uid != pw->pw_uid) \|\|
e9a17296	361	(st.st_mode & 022) != 0)) {
70791e56	362	logit("Authentication refused for %.100s: "
3c0ef626	363	"bad owner or modes for %.200s",
	364	pw->pw_name, user_hostfile);
	365	} else {
	366	temporarily_use_uid(pw);
	367	host_status = check_host_in_hostfile(user_hostfile,
	368	host, key, found, NULL);
	369	restore_uid();
	370	}
	371	xfree(user_hostfile);
	372	}
	373	key_free(found);
	374
	375	debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ?
	376	"ok" : "not found", host);
	377	return host_status;
	378	}
	379
	380
	381	/*
	382	* Check a given file for security. This is defined as all components
e54b3d7c	383	* of the path to the file must be owned by either the owner of
3c0ef626	384	* of the file or root and no directories must be group or world writable.
	385	*
	386	* XXX Should any specific check be done for sym links ?
	387	*
	388	* Takes an open file descriptor, the file name, a uid and and
	389	* error buffer plus max size as arguments.
	390	*
	391	* Returns 0 on success and -1 on failure
	392	*/
	393	int
	394	secure_filename(FILE f, const char file, struct passwd *pw,
	395	char *err, size_t errlen)
	396	{
	397	uid_t uid = pw->pw_uid;
	398	char buf[MAXPATHLEN], homedir[MAXPATHLEN];
	399	char *cp;
1c14df9e	400	int comparehome = 0;
3c0ef626	401	struct stat st;
	402
	403	if (realpath(file, buf) == NULL) {
	404	snprintf(err, errlen, "realpath %s failed: %s", file,
	405	strerror(errno));
	406	return -1;
	407	}
1c14df9e	408	if (realpath(pw->pw_dir, homedir) != NULL)
1c14df9e	409	comparehome = 1;
3c0ef626	410
	411	/* check the open file to avoid races */
	412	if (fstat(fileno(f), &st) < 0 \|\|
	413	(st.st_uid != 0 && st.st_uid != uid) \|\|
	414	(st.st_mode & 022) != 0) {
	415	snprintf(err, errlen, "bad ownership or modes for file %s",
	416	buf);
	417	return -1;
	418	}
	419
	420	/* for each component of the canonical path, walking upwards */
	421	for (;;) {
	422	if ((cp = dirname(buf)) == NULL) {
	423	snprintf(err, errlen, "dirname() failed");
	424	return -1;
	425	}
	426	strlcpy(buf, cp, sizeof(buf));
	427
	428	debug3("secure_filename: checking '%s'", buf);
	429	if (stat(buf, &st) < 0 \|\|
	430	(st.st_uid != 0 && st.st_uid != uid) \|\|
	431	(st.st_mode & 022) != 0) {
e9a17296	432	snprintf(err, errlen,
3c0ef626	433	"bad ownership or modes for directory %s", buf);
	434	return -1;
	435	}
	436
	437	/* If are passed the homedir then we can stop */
1c14df9e	438	if (comparehome && strcmp(homedir, buf) == 0) {
3c0ef626	439	debug3("secure_filename: terminating check at '%s'",
	440	buf);
	441	break;
	442	}
	443	/*
	444	* dirname should always complete with a "/" path,
	445	* but we can be paranoid and check for "." too
	446	*/
	447	if ((strcmp("/", buf) == 0) \|\| (strcmp(".", buf) == 0))
	448	break;
	449	}
	450	return 0;
	451	}
2980ea68	452
	453	struct passwd *
	454	getpwnamallow(const char *user)
	455	{
	456	#ifdef HAVE_LOGIN_CAP
	457	extern login_cap_t *lc;
	458	#ifdef BSD_AUTH
	459	auth_session_t *as;
	460	#endif
	461	#endif
	462	struct passwd *pw;
	463
	464	pw = getpwnam(user);
e54b3d7c	465	if (pw == NULL) {
1b56ff3d	466	logit("Invalid user %.100s from %.100s",
416fd2a8	467	(user && user[0]) ? user : "<implicit>",
416fd2a8	468	get_remote_ipaddr());
70791e56	469	#ifdef CUSTOM_FAILED_LOGIN
70791e56	470	record_failed_login(user, "ssh");
1c14df9e	471	#endif
e54b3d7c	472	return (NULL);
	473	}
	474	if (!allowed_user(pw))
2980ea68	475	return (NULL);
	476	#ifdef HAVE_LOGIN_CAP
	477	if ((lc = login_getclass(pw->pw_class)) == NULL) {
	478	debug("unable to get login class: %s", user);
	479	return (NULL);
	480	}
	481	#ifdef BSD_AUTH
	482	if ((as = auth_open()) == NULL \|\| auth_setpwd(as, pw) != 0 \|\|
	483	auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
	484	debug("Approval failure for %s", user);
	485	pw = NULL;
	486	}
	487	if (as != NULL)
	488	auth_close(as);
	489	#endif
	490	#endif
	491	if (pw != NULL)
	492	return (pwcopy(pw));
	493	return (NULL);
	494	}
	495
	496	void
	497	auth_debug_add(const char *fmt,...)
	498	{
	499	char buf[1024];
	500	va_list args;
	501
	502	if (!auth_debug_init)
	503	return;
	504
	505	va_start(args, fmt);
	506	vsnprintf(buf, sizeof(buf), fmt, args);
	507	va_end(args);
	508	buffer_put_cstring(&auth_debug, buf);
	509	}
	510
	511	void
	512	auth_debug_send(void)
	513	{
	514	char *msg;
	515
	516	if (!auth_debug_init)
	517	return;
	518	while (buffer_len(&auth_debug)) {
	519	msg = buffer_get_string(&auth_debug, NULL);
	520	packet_send_debug("%s", msg);
	521	xfree(msg);
	522	}
	523	}
	524
	525	void
	526	auth_debug_reset(void)
	527	{
	528	if (auth_debug_init)
	529	buffer_clear(&auth_debug);
	530	else {
	531	buffer_init(&auth_debug);
	532	auth_debug_init = 1;
	533	}
	534	}
70791e56	535
	536	struct passwd *
	537	fakepw(void)
	538	{
	539	static struct passwd fake;
	540
	541	memset(&fake, 0, sizeof(fake));
	542	fake.pw_name = "NOUSER";
	543	fake.pw_passwd =
416fd2a8	544	"$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK";
70791e56	545	fake.pw_gecos = "NOUSER";
1b56ff3d	546	fake.pw_uid = (uid_t)-1;
1b56ff3d	547	fake.pw_gid = (gid_t)-1;
70791e56	548	#ifdef HAVE_PW_CLASS_IN_PASSWD
	549	fake.pw_class = "";
	550	#endif
	551	fake.pw_dir = "/nonexist";
	552	fake.pw_shell = "/nonexist";
	553
	554	return (&fake);
	555	}