[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 1.56 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,
	    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, 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
20d0f77f	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"
d77347cc	26	RCSID("$OpenBSD: auth.c,v 1.56 2004/07/28 09:40:29 markus Exp $");
7368a6c8	27
c1ef8333	28	#ifdef HAVE_LOGIN_H
	29	#include <login.h>
	30	#endif
f14ca4a4	31	#ifdef USE_SHADOW
4cb5ffa0	32	#include <shadow.h>
f14ca4a4	33	#endif
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"
5f1f36b5	50	#include "misc.h"
01dafcb5	51	#include "bufaux.h"
01dafcb5	52	#include "packet.h"
e78a59f5	53
7368a6c8	54	/* import */
7368a6c8	55	extern ServerOptions options;
bc7dfc06	56	extern Buffer loginmsg;
7368a6c8	57
01dafcb5	58	/* Debugging messages */
	59	Buffer auth_debug;
	60	int auth_debug_init;
	61
7368a6c8	62	/*
c6a69271	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.
7368a6c8	68	* If the user's shell is not executable, false will be returned.
6ae2364d	69	* Otherwise true is returned.
7368a6c8	70	*/
a306f2dd	71	int
7368a6c8	72	allowed_user(struct passwd * pw)
	73	{
	74	struct stat st;
da67ae18	75	const char hostname = NULL, ipaddr = NULL, *passwd = NULL;
614dee3a	76	char *shell;
7368a6c8	77	int i;
f14ca4a4	78	#ifdef USE_SHADOW
3e6e3da0	79	struct spwd *spw = NULL;
e2ef2342	80	#endif
7368a6c8	81
7368a6c8	82	/* Shouldn't be called if pw is NULL, but better safe than sorry... */
c6a69271	83	if (!pw \|\| !pw->pw_name)
7368a6c8	84	return 0;
7368a6c8	85
f14ca4a4	86	#ifdef USE_SHADOW
3e6e3da0	87	if (!options.use_pam)
	88	spw = getspnam(pw->pw_name);
	89	#ifdef HAS_SHADOW_EXPIRE
f14ca4a4	90	if (!options.use_pam && spw != NULL && auth_shadow_acctexpired(spw))
f14ca4a4	91	return 0;
3e6e3da0	92	#endif /* HAS_SHADOW_EXPIRE */
f14ca4a4	93	#endif /* USE_SHADOW */
3e6e3da0	94
aff51935	95	/* grab passwd field for locked account check */
f14ca4a4	96	#ifdef USE_SHADOW
3e6e3da0	97	if (spw != NULL)
	98	passwd = spw->sp_pwdp;
	99	#else
	100	passwd = pw->pw_passwd;
b57c8e20	101	#endif
b57c8e20	102
aff51935	103	/* check for locked account */
da67ae18	104	if (!options.use_pam && passwd && *passwd) {
3e6e3da0	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
301e9b01	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 */
b334badd	134	if (stat(shell, &st) != 0) {
bbe88b6d	135	logit("User %.100s not allowed because shell %.100s does not exist",
b334badd	136	pw->pw_name, shell);
7368a6c8	137	return 0;
b334badd	138	}
c390a3c8	139	if (S_ISREG(st.st_mode) == 0 \|\|
c390a3c8	140	(st.st_mode & (S_IXOTH\|S_IXUSR\|S_IXGRP)) == 0) {
bbe88b6d	141	logit("User %.100s not allowed because shell %.100s is not executable",
b334badd	142	pw->pw_name, shell);
7368a6c8	143	return 0;
b334badd	144	}
7368a6c8	145
6805fc56	146	if (options.num_deny_users > 0 \|\| options.num_allow_users > 0) {
c5a7d788	147	hostname = get_canonical_hostname(options.use_dns);
6805fc56	148	ipaddr = get_remote_ipaddr();
	149	}
	150
7368a6c8	151	/* Return false if user is listed in DenyUsers */
7368a6c8	152	if (options.num_deny_users > 0) {
7368a6c8	153	for (i = 0; i < options.num_deny_users; i++)
762715ce	154	if (match_user(pw->pw_name, hostname, ipaddr,
b334badd	155	options.deny_users[i])) {
bbe88b6d	156	logit("User %.100s not allowed because listed in DenyUsers",
762715ce	157	pw->pw_name);
7368a6c8	158	return 0;
b334badd	159	}
7368a6c8	160	}
	161	/* Return false if AllowUsers isn't empty and user isn't listed there */
	162	if (options.num_allow_users > 0) {
7368a6c8	163	for (i = 0; i < options.num_allow_users; i++)
762715ce	164	if (match_user(pw->pw_name, hostname, ipaddr,
80f8f24f	165	options.allow_users[i]))
7368a6c8	166	break;
7368a6c8	167	/* i < options.num_allow_users iff we break for loop */
b334badd	168	if (i >= options.num_allow_users) {
bbe88b6d	169	logit("User %.100s not allowed because not listed in AllowUsers",
b334badd	170	pw->pw_name);
7368a6c8	171	return 0;
b334badd	172	}
7368a6c8	173	}
7368a6c8	174	if (options.num_deny_groups > 0 \|\| options.num_allow_groups > 0) {
c6a69271	175	/* Get the user's group access list (primary and supplementary) */
b334badd	176	if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
bbe88b6d	177	logit("User %.100s not allowed because not in any group",
b334badd	178	pw->pw_name);
7368a6c8	179	return 0;
b334badd	180	}
7368a6c8	181
c6a69271	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();
bbe88b6d	187	logit("User %.100s not allowed because a group is listed in DenyGroups",
b334badd	188	pw->pw_name);
7368a6c8	189	return 0;
c6a69271	190	}
7368a6c8	191	/*
c6a69271	192	* Return false if AllowGroups isn't empty and one of user's groups
7368a6c8	193	* isn't listed there
7368a6c8	194	*/
c6a69271	195	if (options.num_allow_groups > 0)
	196	if (!ga_match(options.allow_groups,
	197	options.num_allow_groups)) {
	198	ga_free();
bbe88b6d	199	logit("User %.100s not allowed because none of user's groups are listed in AllowGroups",
b334badd	200	pw->pw_name);
7368a6c8	201	return 0;
c6a69271	202	}
c6a69271	203	ga_free();
7368a6c8	204	}
7368a6c8	205
bc5c2025	206	#ifdef CUSTOM_SYS_AUTH_ALLOWED_USER
	207	if (!sys_auth_allowed_user(pw))
	208	return 0;
	209	#endif
7368a6c8	210
	211	/* We found no reason not to let this user try to log on... */
	212	return 1;
	213	}
59c97189	214
59c97189	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 \|\|
af4bd935	224	authctxt->failures >= options.max_authtries / 2 \|\|
59c97189	225	strcmp(method, "password") == 0)
a3568201	226	authlog = logit;
59c97189	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,
d77347cc	236	authctxt->valid ? "" : "invalid user ",
fad3754c	237	authctxt->user,
59c97189	238	get_remote_ipaddr(),
	239	get_remote_port(),
	240	info);
56fd97d7	241
73d9dad3	242	#ifdef CUSTOM_FAILED_LOGIN
56fd97d7	243	if (authenticated == 0 && strcmp(method, "password") == 0)
73d9dad3	244	record_failed_login(authctxt->user, "ssh");
73d9dad3	245	#endif
59c97189	246	}
	247
	248	/*
15853e93	249	* Check whether root logins are disallowed.
59c97189	250	*/
59c97189	251	int
15853e93	252	auth_root_allowed(char *method)
59c97189	253	{
15853e93	254	switch (options.permit_root_login) {
15853e93	255	case PERMIT_YES:
59c97189	256	return 1;
15853e93	257	break;
	258	case PERMIT_NO_PASSWD:
	259	if (strcmp(method, "password") != 0)
	260	return 1;
	261	break;
	262	case PERMIT_FORCED_ONLY:
	263	if (forced_command) {
bbe88b6d	264	logit("Root login accepted for forced command.");
15853e93	265	return 1;
	266	}
	267	break;
59c97189	268	}
bbe88b6d	269	logit("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
15853e93	270	return 0;
59c97189	271	}
c8445989	272
	273
	274	/*
	275	* Given a template and a passwd structure, build a filename
	276	* by substituting % tokenised options. Currently, %% becomes '%',
	277	* %h becomes the home directory and %u the username.
	278	*
	279	* This returns a buffer allocated by xmalloc.
	280	*/
	281	char *
	282	expand_filename(const char filename, struct passwd pw)
	283	{
	284	Buffer buffer;
	285	char *file;
	286	const char *cp;
	287
	288	/*
	289	* Build the filename string in the buffer by making the appropriate
	290	* substitutions to the given file name.
	291	*/
	292	buffer_init(&buffer);
	293	for (cp = filename; *cp; cp++) {
	294	if (cp[0] == '%' && cp[1] == '%') {
	295	buffer_append(&buffer, "%", 1);
	296	cp++;
	297	continue;
	298	}
	299	if (cp[0] == '%' && cp[1] == 'h') {
	300	buffer_append(&buffer, pw->pw_dir, strlen(pw->pw_dir));
	301	cp++;
	302	continue;
	303	}
	304	if (cp[0] == '%' && cp[1] == 'u') {
	305	buffer_append(&buffer, pw->pw_name,
184eed6a	306	strlen(pw->pw_name));
c8445989	307	cp++;
	308	continue;
	309	}
	310	buffer_append(&buffer, cp, 1);
	311	}
	312	buffer_append(&buffer, "\0", 1);
	313
	314	/*
	315	* Ensure that filename starts anchored. If not, be backward
	316	* compatible and prepend the '%h/'
	317	*/
	318	file = xmalloc(MAXPATHLEN);
	319	cp = buffer_ptr(&buffer);
	320	if (*cp != '/')
	321	snprintf(file, MAXPATHLEN, "%s/%s", pw->pw_dir, cp);
	322	else
	323	strlcpy(file, cp, MAXPATHLEN);
	324
	325	buffer_free(&buffer);
	326	return file;
	327	}
	328
	329	char *
	330	authorized_keys_file(struct passwd *pw)
	331	{
	332	return expand_filename(options.authorized_keys_file, pw);
	333	}
	334
	335	char *
	336	authorized_keys_file2(struct passwd *pw)
	337	{
	338	return expand_filename(options.authorized_keys_file2, pw);
	339	}
	340
d0c8ca5c	341	/* return ok if key exists in sysfile or userfile */
	342	HostStatus
	343	check_key_in_hostfiles(struct passwd pw, Key key, const char *host,
	344	const char sysfile, const char userfile)
	345	{
	346	Key *found;
	347	char *user_hostfile;
	348	struct stat st;
17a3011c	349	HostStatus host_status;
d0c8ca5c	350
	351	/* Check if we know the host and its host key. */
	352	found = key_new(key->type);
	353	host_status = check_host_in_hostfile(sysfile, host, key, found, NULL);
	354
	355	if (host_status != HOST_OK && userfile != NULL) {
	356	user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
	357	if (options.strict_modes &&
	358	(stat(user_hostfile, &st) == 0) &&
	359	((st.st_uid != 0 && st.st_uid != pw->pw_uid) \|\|
184eed6a	360	(st.st_mode & 022) != 0)) {
bbe88b6d	361	logit("Authentication refused for %.100s: "
d0c8ca5c	362	"bad owner or modes for %.200s",
	363	pw->pw_name, user_hostfile);
	364	} else {
	365	temporarily_use_uid(pw);
	366	host_status = check_host_in_hostfile(user_hostfile,
	367	host, key, found, NULL);
	368	restore_uid();
	369	}
	370	xfree(user_hostfile);
	371	}
	372	key_free(found);
	373
	374	debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ?
	375	"ok" : "not found", host);
	376	return host_status;
	377	}
	378
	379
c8445989	380	/*
c8445989	381	* Check a given file for security. This is defined as all components
d6097023	382	* of the path to the file must be owned by either the owner of
1ddf764b	383	* of the file or root and no directories must be group or world writable.
c8445989	384	*
	385	* XXX Should any specific check be done for sym links ?
	386	*
	387	* Takes an open file descriptor, the file name, a uid and and
	388	* error buffer plus max size as arguments.
	389	*
	390	* Returns 0 on success and -1 on failure
	391	*/
	392	int
6978866a	393	secure_filename(FILE f, const char file, struct passwd *pw,
6978866a	394	char *err, size_t errlen)
c8445989	395	{
6978866a	396	uid_t uid = pw->pw_uid;
76fbdd47	397	char buf[MAXPATHLEN], homedir[MAXPATHLEN];
c8445989	398	char *cp;
f6f02456	399	int comparehome = 0;
c8445989	400	struct stat st;
	401
	402	if (realpath(file, buf) == NULL) {
	403	snprintf(err, errlen, "realpath %s failed: %s", file,
	404	strerror(errno));
	405	return -1;
	406	}
f6f02456	407	if (realpath(pw->pw_dir, homedir) != NULL)
f6f02456	408	comparehome = 1;
c8445989	409
	410	/* check the open file to avoid races */
	411	if (fstat(fileno(f), &st) < 0 \|\|
	412	(st.st_uid != 0 && st.st_uid != uid) \|\|
	413	(st.st_mode & 022) != 0) {
	414	snprintf(err, errlen, "bad ownership or modes for file %s",
	415	buf);
	416	return -1;
	417	}
	418
	419	/* for each component of the canonical path, walking upwards */
	420	for (;;) {
	421	if ((cp = dirname(buf)) == NULL) {
	422	snprintf(err, errlen, "dirname() failed");
	423	return -1;
	424	}
	425	strlcpy(buf, cp, sizeof(buf));
	426
	427	debug3("secure_filename: checking '%s'", buf);
	428	if (stat(buf, &st) < 0 \|\|
	429	(st.st_uid != 0 && st.st_uid != uid) \|\|
	430	(st.st_mode & 022) != 0) {
184eed6a	431	snprintf(err, errlen,
c8445989	432	"bad ownership or modes for directory %s", buf);
	433	return -1;
	434	}
	435
afd501f9	436	/* If are passed the homedir then we can stop */
f6f02456	437	if (comparehome && strcmp(homedir, buf) == 0) {
afd501f9	438	debug3("secure_filename: terminating check at '%s'",
	439	buf);
	440	break;
	441	}
c8445989	442	/*
	443	* dirname should always complete with a "/" path,
	444	* but we can be paranoid and check for "." too
	445	*/
	446	if ((strcmp("/", buf) == 0) \|\| (strcmp(".", buf) == 0))
	447	break;
	448	}
	449	return 0;
	450	}
443fa1cd	451
	452	struct passwd *
	453	getpwnamallow(const char *user)
	454	{
1836f69f	455	#ifdef HAVE_LOGIN_CAP
	456	extern login_cap_t *lc;
	457	#ifdef BSD_AUTH
	458	auth_session_t *as;
	459	#endif
	460	#endif
443fa1cd	461	struct passwd *pw;
	462
	463	pw = getpwnam(user);
c2802d92	464	if (pw == NULL) {
227a6a97	465	logit("Invalid user %.100s from %.100s",
c2802d92	466	user, get_remote_ipaddr());
73d9dad3	467	#ifdef CUSTOM_FAILED_LOGIN
73d9dad3	468	record_failed_login(user, "ssh");
819d3f09	469	#endif
c2802d92	470	return (NULL);
	471	}
	472	if (!allowed_user(pw))
1836f69f	473	return (NULL);
	474	#ifdef HAVE_LOGIN_CAP
	475	if ((lc = login_getclass(pw->pw_class)) == NULL) {
	476	debug("unable to get login class: %s", user);
	477	return (NULL);
	478	}
	479	#ifdef BSD_AUTH
	480	if ((as = auth_open()) == NULL \|\| auth_setpwd(as, pw) != 0 \|\|
65721f9c	481	auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
1836f69f	482	debug("Approval failure for %s", user);
443fa1cd	483	pw = NULL;
1836f69f	484	}
	485	if (as != NULL)
	486	auth_close(as);
	487	#endif
	488	#endif
06bea668	489	if (pw != NULL)
	490	return (pwcopy(pw));
	491	return (NULL);
443fa1cd	492	}
01dafcb5	493
	494	void
	495	auth_debug_add(const char *fmt,...)
	496	{
	497	char buf[1024];
	498	va_list args;
	499
	500	if (!auth_debug_init)
	501	return;
	502
	503	va_start(args, fmt);
	504	vsnprintf(buf, sizeof(buf), fmt, args);
	505	va_end(args);
	506	buffer_put_cstring(&auth_debug, buf);
	507	}
	508
	509	void
	510	auth_debug_send(void)
	511	{
	512	char *msg;
	513
	514	if (!auth_debug_init)
	515	return;
	516	while (buffer_len(&auth_debug)) {
	517	msg = buffer_get_string(&auth_debug, NULL);
	518	packet_send_debug("%s", msg);
	519	xfree(msg);
	520	}
	521	}
	522
	523	void
	524	auth_debug_reset(void)
	525	{
	526	if (auth_debug_init)
	527	buffer_clear(&auth_debug);
	528	else {
	529	buffer_init(&auth_debug);
	530	auth_debug_init = 1;
	531	}
	532	}
96d0bf74	533
	534	struct passwd *
	535	fakepw(void)
	536	{
	537	static struct passwd fake;
	538
	539	memset(&fake, 0, sizeof(fake));
	540	fake.pw_name = "NOUSER";
	541	fake.pw_passwd =
b6453d99	542	"$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK";
96d0bf74	543	fake.pw_gecos = "NOUSER";
f6be21a0	544	fake.pw_uid = (uid_t)-1;
f6be21a0	545	fake.pw_gid = (gid_t)-1;
96d0bf74	546	#ifdef HAVE_PW_CLASS_IN_PASSWD
	547	fake.pw_class = "";
	548	#endif
	549	fake.pw_dir = "/nonexist";
	550	fake.pw_shell = "/nonexist";
	551
	552	return (&fake);
	553	}