[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 1.51 2003/11/21 11:57:02 djm 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 "tildexpand.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 WITH_AIXAUTHENTICATE
	/*
	 * Don't check loginrestrictions() for root account (use
	 * PermitRootLogin to control logins via ssh), or if running as
	 * non-root user (since loginrestrictions will always fail).
	 */
	if ((pw->pw_uid != 0) && (geteuid() == 0)) {
		char *msg;

		if (loginrestrictions(pw->pw_name, S_RLOGIN, NULL, &msg) != 0) {
			int loginrestrict_errno = errno;

			if (msg && *msg) {
				buffer_append(&loginmsg, msg, strlen(msg));
				aix_remove_embedded_newlines(msg);
				logit("Login restricted for %s: %.100s",
				    pw->pw_name, msg);
			}
			/* Don't fail if /etc/nologin  set */
			if (!(loginrestrict_errno == EPERM &&
			    stat(_PATH_NOLOGIN, &st) == 0))
				return 0;
		}
	}
#endif /* WITH_AIXAUTHENTICATE */

	/* 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 >= AUTH_FAIL_LOG ||
	    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 ? "" : "illegal 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("Illegal 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 = -1;
	fake.pw_gid = -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"
aff51935	26	RCSID("$OpenBSD: auth.c,v 1.51 2003/11/21 11:57:02 djm 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"
d0c8ca5c	50	#include "tildexpand.h"
5f1f36b5	51	#include "misc.h"
01dafcb5	52	#include "bufaux.h"
01dafcb5	53	#include "packet.h"
e78a59f5	54
7368a6c8	55	/* import */
7368a6c8	56	extern ServerOptions options;
bc7dfc06	57	extern Buffer loginmsg;
7368a6c8	58
01dafcb5	59	/* Debugging messages */
	60	Buffer auth_debug;
	61	int auth_debug_init;
	62
7368a6c8	63	/*
c6a69271	64	* Check if the user is allowed to log in via ssh. If user is listed
	65	* in DenyUsers or one of user's groups is listed in DenyGroups, false
	66	* will be returned. If AllowUsers isn't empty and user isn't listed
	67	* there, or if AllowGroups isn't empty and one of user's groups isn't
	68	* listed there, false will be returned.
7368a6c8	69	* If the user's shell is not executable, false will be returned.
6ae2364d	70	* Otherwise true is returned.
7368a6c8	71	*/
a306f2dd	72	int
7368a6c8	73	allowed_user(struct passwd * pw)
	74	{
	75	struct stat st;
da67ae18	76	const char hostname = NULL, ipaddr = NULL, *passwd = NULL;
614dee3a	77	char *shell;
7368a6c8	78	int i;
f14ca4a4	79	#ifdef USE_SHADOW
3e6e3da0	80	struct spwd *spw = NULL;
e2ef2342	81	#endif
7368a6c8	82
7368a6c8	83	/* Shouldn't be called if pw is NULL, but better safe than sorry... */
c6a69271	84	if (!pw \|\| !pw->pw_name)
7368a6c8	85	return 0;
7368a6c8	86
f14ca4a4	87	#ifdef USE_SHADOW
3e6e3da0	88	if (!options.use_pam)
	89	spw = getspnam(pw->pw_name);
	90	#ifdef HAS_SHADOW_EXPIRE
f14ca4a4	91	if (!options.use_pam && spw != NULL && auth_shadow_acctexpired(spw))
f14ca4a4	92	return 0;
3e6e3da0	93	#endif /* HAS_SHADOW_EXPIRE */
f14ca4a4	94	#endif /* USE_SHADOW */
3e6e3da0	95
aff51935	96	/* grab passwd field for locked account check */
f14ca4a4	97	#ifdef USE_SHADOW
3e6e3da0	98	if (spw != NULL)
	99	passwd = spw->sp_pwdp;
	100	#else
	101	passwd = pw->pw_passwd;
b57c8e20	102	#endif
b57c8e20	103
aff51935	104	/* check for locked account */
da67ae18	105	if (!options.use_pam && passwd && *passwd) {
3e6e3da0	106	int locked = 0;
	107
	108	#ifdef LOCKED_PASSWD_STRING
	109	if (strcmp(passwd, LOCKED_PASSWD_STRING) == 0)
	110	locked = 1;
	111	#endif
	112	#ifdef LOCKED_PASSWD_PREFIX
	113	if (strncmp(passwd, LOCKED_PASSWD_PREFIX,
	114	strlen(LOCKED_PASSWD_PREFIX)) == 0)
	115	locked = 1;
	116	#endif
	117	#ifdef LOCKED_PASSWD_SUBSTR
	118	if (strstr(passwd, LOCKED_PASSWD_SUBSTR))
	119	locked = 1;
	120	#endif
	121	if (locked) {
	122	logit("User %.100s not allowed because account is locked",
	123	pw->pw_name);
	124	return 0;
	125	}
	126	}
	127
301e9b01	128	/*
	129	* Get the shell from the password data. An empty shell field is
	130	* legal, and means /bin/sh.
	131	*/
	132	shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;
	133
	134	/* deny if shell does not exists or is not executable */
b334badd	135	if (stat(shell, &st) != 0) {
bbe88b6d	136	logit("User %.100s not allowed because shell %.100s does not exist",
b334badd	137	pw->pw_name, shell);
7368a6c8	138	return 0;
b334badd	139	}
c390a3c8	140	if (S_ISREG(st.st_mode) == 0 \|\|
c390a3c8	141	(st.st_mode & (S_IXOTH\|S_IXUSR\|S_IXGRP)) == 0) {
bbe88b6d	142	logit("User %.100s not allowed because shell %.100s is not executable",
b334badd	143	pw->pw_name, shell);
7368a6c8	144	return 0;
b334badd	145	}
7368a6c8	146
6805fc56	147	if (options.num_deny_users > 0 \|\| options.num_allow_users > 0) {
c5a7d788	148	hostname = get_canonical_hostname(options.use_dns);
6805fc56	149	ipaddr = get_remote_ipaddr();
	150	}
	151
7368a6c8	152	/* Return false if user is listed in DenyUsers */
7368a6c8	153	if (options.num_deny_users > 0) {
7368a6c8	154	for (i = 0; i < options.num_deny_users; i++)
762715ce	155	if (match_user(pw->pw_name, hostname, ipaddr,
b334badd	156	options.deny_users[i])) {
bbe88b6d	157	logit("User %.100s not allowed because listed in DenyUsers",
762715ce	158	pw->pw_name);
7368a6c8	159	return 0;
b334badd	160	}
7368a6c8	161	}
	162	/* Return false if AllowUsers isn't empty and user isn't listed there */
	163	if (options.num_allow_users > 0) {
7368a6c8	164	for (i = 0; i < options.num_allow_users; i++)
762715ce	165	if (match_user(pw->pw_name, hostname, ipaddr,
80f8f24f	166	options.allow_users[i]))
7368a6c8	167	break;
7368a6c8	168	/* i < options.num_allow_users iff we break for loop */
b334badd	169	if (i >= options.num_allow_users) {
bbe88b6d	170	logit("User %.100s not allowed because not listed in AllowUsers",
b334badd	171	pw->pw_name);
7368a6c8	172	return 0;
b334badd	173	}
7368a6c8	174	}
7368a6c8	175	if (options.num_deny_groups > 0 \|\| options.num_allow_groups > 0) {
c6a69271	176	/* Get the user's group access list (primary and supplementary) */
b334badd	177	if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
bbe88b6d	178	logit("User %.100s not allowed because not in any group",
b334badd	179	pw->pw_name);
7368a6c8	180	return 0;
b334badd	181	}
7368a6c8	182
c6a69271	183	/* Return false if one of user's groups is listed in DenyGroups */
	184	if (options.num_deny_groups > 0)
	185	if (ga_match(options.deny_groups,
	186	options.num_deny_groups)) {
	187	ga_free();
bbe88b6d	188	logit("User %.100s not allowed because a group is listed in DenyGroups",
b334badd	189	pw->pw_name);
7368a6c8	190	return 0;
c6a69271	191	}
7368a6c8	192	/*
c6a69271	193	* Return false if AllowGroups isn't empty and one of user's groups
7368a6c8	194	* isn't listed there
7368a6c8	195	*/
c6a69271	196	if (options.num_allow_groups > 0)
	197	if (!ga_match(options.allow_groups,
	198	options.num_allow_groups)) {
	199	ga_free();
bbe88b6d	200	logit("User %.100s not allowed because none of user's groups are listed in AllowGroups",
b334badd	201	pw->pw_name);
7368a6c8	202	return 0;
c6a69271	203	}
c6a69271	204	ga_free();
7368a6c8	205	}
	206
	207	#ifdef WITH_AIXAUTHENTICATE
f3e87063	208	/*
	209	* Don't check loginrestrictions() for root account (use
	210	* PermitRootLogin to control logins via ssh), or if running as
	211	* non-root user (since loginrestrictions will always fail).
	212	*/
bc7dfc06	213	if ((pw->pw_uid != 0) && (geteuid() == 0)) {
	214	char *msg;
	215
aff51935	216	if (loginrestrictions(pw->pw_name, S_RLOGIN, NULL, &msg) != 0) {
bc7dfc06	217	int loginrestrict_errno = errno;
	218
	219	if (msg && *msg) {
	220	buffer_append(&loginmsg, msg, strlen(msg));
	221	aix_remove_embedded_newlines(msg);
	222	logit("Login restricted for %s: %.100s",
	223	pw->pw_name, msg);
5daf7064	224	}
bc7dfc06	225	/* Don't fail if /etc/nologin set */
aff51935	226	if (!(loginrestrict_errno == EPERM &&
bc7dfc06	227	stat(_PATH_NOLOGIN, &st) == 0))
bc7dfc06	228	return 0;
c1ef8333	229	}
c1ef8333	230	}
7368a6c8	231	#endif /* WITH_AIXAUTHENTICATE */
	232
	233	/* We found no reason not to let this user try to log on... */
	234	return 1;
	235	}
59c97189	236
59c97189	237	void
	238	auth_log(Authctxt authctxt, int authenticated, char method, char *info)
	239	{
	240	void (authlog) (const char fmt,...) = verbose;
	241	char *authmsg;
	242
	243	/* Raise logging level */
	244	if (authenticated == 1 \|\|
	245	!authctxt->valid \|\|
	246	authctxt->failures >= AUTH_FAIL_LOG \|\|
	247	strcmp(method, "password") == 0)
a3568201	248	authlog = logit;
59c97189	249
	250	if (authctxt->postponed)
	251	authmsg = "Postponed";
	252	else
	253	authmsg = authenticated ? "Accepted" : "Failed";
	254
	255	authlog("%s %s for %s%.100s from %.200s port %d%s",
	256	authmsg,
	257	method,
	258	authctxt->valid ? "" : "illegal user ",
fad3754c	259	authctxt->user,
59c97189	260	get_remote_ipaddr(),
	261	get_remote_port(),
	262	info);
56fd97d7	263
73d9dad3	264	#ifdef CUSTOM_FAILED_LOGIN
56fd97d7	265	if (authenticated == 0 && strcmp(method, "password") == 0)
73d9dad3	266	record_failed_login(authctxt->user, "ssh");
73d9dad3	267	#endif
59c97189	268	}
	269
	270	/*
15853e93	271	* Check whether root logins are disallowed.
59c97189	272	*/
59c97189	273	int
15853e93	274	auth_root_allowed(char *method)
59c97189	275	{
15853e93	276	switch (options.permit_root_login) {
15853e93	277	case PERMIT_YES:
59c97189	278	return 1;
15853e93	279	break;
	280	case PERMIT_NO_PASSWD:
	281	if (strcmp(method, "password") != 0)
	282	return 1;
	283	break;
	284	case PERMIT_FORCED_ONLY:
	285	if (forced_command) {
bbe88b6d	286	logit("Root login accepted for forced command.");
15853e93	287	return 1;
	288	}
	289	break;
59c97189	290	}
bbe88b6d	291	logit("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
15853e93	292	return 0;
59c97189	293	}
c8445989	294
	295
	296	/*
	297	* Given a template and a passwd structure, build a filename
	298	* by substituting % tokenised options. Currently, %% becomes '%',
	299	* %h becomes the home directory and %u the username.
	300	*
	301	* This returns a buffer allocated by xmalloc.
	302	*/
	303	char *
	304	expand_filename(const char filename, struct passwd pw)
	305	{
	306	Buffer buffer;
	307	char *file;
	308	const char *cp;
	309
	310	/*
	311	* Build the filename string in the buffer by making the appropriate
	312	* substitutions to the given file name.
	313	*/
	314	buffer_init(&buffer);
	315	for (cp = filename; *cp; cp++) {
	316	if (cp[0] == '%' && cp[1] == '%') {
	317	buffer_append(&buffer, "%", 1);
	318	cp++;
	319	continue;
	320	}
	321	if (cp[0] == '%' && cp[1] == 'h') {
	322	buffer_append(&buffer, pw->pw_dir, strlen(pw->pw_dir));
	323	cp++;
	324	continue;
	325	}
	326	if (cp[0] == '%' && cp[1] == 'u') {
	327	buffer_append(&buffer, pw->pw_name,
184eed6a	328	strlen(pw->pw_name));
c8445989	329	cp++;
	330	continue;
	331	}
	332	buffer_append(&buffer, cp, 1);
	333	}
	334	buffer_append(&buffer, "\0", 1);
	335
	336	/*
	337	* Ensure that filename starts anchored. If not, be backward
	338	* compatible and prepend the '%h/'
	339	*/
	340	file = xmalloc(MAXPATHLEN);
	341	cp = buffer_ptr(&buffer);
	342	if (*cp != '/')
	343	snprintf(file, MAXPATHLEN, "%s/%s", pw->pw_dir, cp);
	344	else
	345	strlcpy(file, cp, MAXPATHLEN);
	346
	347	buffer_free(&buffer);
	348	return file;
	349	}
	350
	351	char *
	352	authorized_keys_file(struct passwd *pw)
	353	{
	354	return expand_filename(options.authorized_keys_file, pw);
	355	}
	356
	357	char *
	358	authorized_keys_file2(struct passwd *pw)
	359	{
	360	return expand_filename(options.authorized_keys_file2, pw);
	361	}
	362
d0c8ca5c	363	/* return ok if key exists in sysfile or userfile */
	364	HostStatus
	365	check_key_in_hostfiles(struct passwd pw, Key key, const char *host,
	366	const char sysfile, const char userfile)
	367	{
	368	Key *found;
	369	char *user_hostfile;
	370	struct stat st;
17a3011c	371	HostStatus host_status;
d0c8ca5c	372
	373	/* Check if we know the host and its host key. */
	374	found = key_new(key->type);
	375	host_status = check_host_in_hostfile(sysfile, host, key, found, NULL);
	376
	377	if (host_status != HOST_OK && userfile != NULL) {
	378	user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
	379	if (options.strict_modes &&
	380	(stat(user_hostfile, &st) == 0) &&
	381	((st.st_uid != 0 && st.st_uid != pw->pw_uid) \|\|
184eed6a	382	(st.st_mode & 022) != 0)) {
bbe88b6d	383	logit("Authentication refused for %.100s: "
d0c8ca5c	384	"bad owner or modes for %.200s",
	385	pw->pw_name, user_hostfile);
	386	} else {
	387	temporarily_use_uid(pw);
	388	host_status = check_host_in_hostfile(user_hostfile,
	389	host, key, found, NULL);
	390	restore_uid();
	391	}
	392	xfree(user_hostfile);
	393	}
	394	key_free(found);
	395
	396	debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ?
	397	"ok" : "not found", host);
	398	return host_status;
	399	}
	400
	401
c8445989	402	/*
c8445989	403	* Check a given file for security. This is defined as all components
d6097023	404	* of the path to the file must be owned by either the owner of
1ddf764b	405	* of the file or root and no directories must be group or world writable.
c8445989	406	*
	407	* XXX Should any specific check be done for sym links ?
	408	*
	409	* Takes an open file descriptor, the file name, a uid and and
	410	* error buffer plus max size as arguments.
	411	*
	412	* Returns 0 on success and -1 on failure
	413	*/
	414	int
6978866a	415	secure_filename(FILE f, const char file, struct passwd *pw,
6978866a	416	char *err, size_t errlen)
c8445989	417	{
6978866a	418	uid_t uid = pw->pw_uid;
76fbdd47	419	char buf[MAXPATHLEN], homedir[MAXPATHLEN];
c8445989	420	char *cp;
f6f02456	421	int comparehome = 0;
c8445989	422	struct stat st;
	423
	424	if (realpath(file, buf) == NULL) {
	425	snprintf(err, errlen, "realpath %s failed: %s", file,
	426	strerror(errno));
	427	return -1;
	428	}
f6f02456	429	if (realpath(pw->pw_dir, homedir) != NULL)
f6f02456	430	comparehome = 1;
c8445989	431
	432	/* check the open file to avoid races */
	433	if (fstat(fileno(f), &st) < 0 \|\|
	434	(st.st_uid != 0 && st.st_uid != uid) \|\|
	435	(st.st_mode & 022) != 0) {
	436	snprintf(err, errlen, "bad ownership or modes for file %s",
	437	buf);
	438	return -1;
	439	}
	440
	441	/* for each component of the canonical path, walking upwards */
	442	for (;;) {
	443	if ((cp = dirname(buf)) == NULL) {
	444	snprintf(err, errlen, "dirname() failed");
	445	return -1;
	446	}
	447	strlcpy(buf, cp, sizeof(buf));
	448
	449	debug3("secure_filename: checking '%s'", buf);
	450	if (stat(buf, &st) < 0 \|\|
	451	(st.st_uid != 0 && st.st_uid != uid) \|\|
	452	(st.st_mode & 022) != 0) {
184eed6a	453	snprintf(err, errlen,
c8445989	454	"bad ownership or modes for directory %s", buf);
	455	return -1;
	456	}
	457
afd501f9	458	/* If are passed the homedir then we can stop */
f6f02456	459	if (comparehome && strcmp(homedir, buf) == 0) {
afd501f9	460	debug3("secure_filename: terminating check at '%s'",
	461	buf);
	462	break;
	463	}
c8445989	464	/*
	465	* dirname should always complete with a "/" path,
	466	* but we can be paranoid and check for "." too
	467	*/
	468	if ((strcmp("/", buf) == 0) \|\| (strcmp(".", buf) == 0))
	469	break;
	470	}
	471	return 0;
	472	}
443fa1cd	473
	474	struct passwd *
	475	getpwnamallow(const char *user)
	476	{
1836f69f	477	#ifdef HAVE_LOGIN_CAP
	478	extern login_cap_t *lc;
	479	#ifdef BSD_AUTH
	480	auth_session_t *as;
	481	#endif
	482	#endif
443fa1cd	483	struct passwd *pw;
	484
	485	pw = getpwnam(user);
c2802d92	486	if (pw == NULL) {
bbe88b6d	487	logit("Illegal user %.100s from %.100s",
c2802d92	488	user, get_remote_ipaddr());
73d9dad3	489	#ifdef CUSTOM_FAILED_LOGIN
73d9dad3	490	record_failed_login(user, "ssh");
819d3f09	491	#endif
c2802d92	492	return (NULL);
	493	}
	494	if (!allowed_user(pw))
1836f69f	495	return (NULL);
	496	#ifdef HAVE_LOGIN_CAP
	497	if ((lc = login_getclass(pw->pw_class)) == NULL) {
	498	debug("unable to get login class: %s", user);
	499	return (NULL);
	500	}
	501	#ifdef BSD_AUTH
	502	if ((as = auth_open()) == NULL \|\| auth_setpwd(as, pw) != 0 \|\|
65721f9c	503	auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
1836f69f	504	debug("Approval failure for %s", user);
443fa1cd	505	pw = NULL;
1836f69f	506	}
	507	if (as != NULL)
	508	auth_close(as);
	509	#endif
	510	#endif
06bea668	511	if (pw != NULL)
	512	return (pwcopy(pw));
	513	return (NULL);
443fa1cd	514	}
01dafcb5	515
	516	void
	517	auth_debug_add(const char *fmt,...)
	518	{
	519	char buf[1024];
	520	va_list args;
	521
	522	if (!auth_debug_init)
	523	return;
	524
	525	va_start(args, fmt);
	526	vsnprintf(buf, sizeof(buf), fmt, args);
	527	va_end(args);
	528	buffer_put_cstring(&auth_debug, buf);
	529	}
	530
	531	void
	532	auth_debug_send(void)
	533	{
	534	char *msg;
	535
	536	if (!auth_debug_init)
	537	return;
	538	while (buffer_len(&auth_debug)) {
	539	msg = buffer_get_string(&auth_debug, NULL);
	540	packet_send_debug("%s", msg);
	541	xfree(msg);
	542	}
	543	}
	544
	545	void
	546	auth_debug_reset(void)
	547	{
	548	if (auth_debug_init)
	549	buffer_clear(&auth_debug);
	550	else {
	551	buffer_init(&auth_debug);
	552	auth_debug_init = 1;
	553	}
	554	}
96d0bf74	555
	556	struct passwd *
	557	fakepw(void)
	558	{
	559	static struct passwd fake;
	560
	561	memset(&fake, 0, sizeof(fake));
	562	fake.pw_name = "NOUSER";
	563	fake.pw_passwd =
b6453d99	564	"$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK";
96d0bf74	565	fake.pw_gecos = "NOUSER";
	566	fake.pw_uid = -1;
	567	fake.pw_gid = -1;
	568	#ifdef HAVE_PW_CLASS_IN_PASSWD
	569	fake.pw_class = "";
	570	#endif
	571	fake.pw_dir = "/nonexist";
	572	fake.pw_shell = "/nonexist";
	573
	574	return (&fake);
	575	}