[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 1.49 2003/08/26 09:58:43 markus Exp $");

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

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

#include "xmalloc.h"
#include "match.h"
#include "groupaccess.h"
#include "log.h"
#include "servconf.h"
#include "auth.h"
#include "auth-options.h"
#include "canohost.h"
#include "buffer.h"
#include "bufaux.h"
#include "uidswap.h"
#include "tildexpand.h"
#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;
#if defined(HAVE_SHADOW_H) && !defined(DISABLE_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;

#if defined(HAVE_SHADOW_H) && !defined(DISABLE_SHADOW)
	if (!options.use_pam)
		spw = getspnam(pw->pw_name);
#ifdef HAS_SHADOW_EXPIRE
#define	DAY		(24L * 60 * 60) /* 1 day in seconds */
	if (!options.use_pam && spw != NULL) {
		time_t today;

		today = time(NULL) / DAY;
		debug3("allowed_user: today %d sp_expire %d sp_lstchg %d"
		    " sp_max %d", (int)today, (int)spw->sp_expire,
		    (int)spw->sp_lstchg, (int)spw->sp_max);

		/*
		 * We assume account and password expiration occurs the
		 * day after the day specified.
		 */
		if (spw->sp_expire != -1 && today > spw->sp_expire) {
			logit("Account %.100s has expired", pw->pw_name);
			return 0;
		}

		if (spw->sp_lstchg == 0) {
			logit("User %.100s password has expired (root forced)",
			    pw->pw_name);
			return 0;
		}

		if (spw->sp_max != -1 &&
		    today > spw->sp_lstchg + spw->sp_max) {
			logit("User %.100s password has expired (password aged)",
			    pw->pw_name);
			return 0;
		}
	}
#endif /* HAS_SHADOW_EXPIRE */
#endif /* defined(HAVE_SHADOW_H) && !defined(DISABLE_SHADOW) */

    	/* grab passwd field for locked account check */
#if defined(HAVE_SHADOW_H) && !defined(DISABLE_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;
}

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

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

	/* Raise logging level */
	if (authenticated == 1 ||
	    !authctxt->valid ||
	    authctxt->failures >= AUTH_FAIL_LOG ||
	    strcmp(method, "password") == 0)
		authlog = 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[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("Illegal 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 = -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
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"
7cac2b65	26	RCSID("$OpenBSD: auth.c,v 1.49 2003/08/26 09:58:43 markus Exp $");
3c0ef626	27
	28	#ifdef HAVE_LOGIN_H
	29	#include <login.h>
	30	#endif
	31	#if defined(HAVE_SHADOW_H) && !defined(DISABLE_SHADOW)
	32	#include <shadow.h>
	33	#endif /* defined(HAVE_SHADOW_H) && !defined(DISABLE_SHADOW) */
	34
	35	#ifdef HAVE_LIBGEN_H
	36	#include <libgen.h>
	37	#endif
	38
	39	#include "xmalloc.h"
	40	#include "match.h"
	41	#include "groupaccess.h"
	42	#include "log.h"
	43	#include "servconf.h"
	44	#include "auth.h"
	45	#include "auth-options.h"
	46	#include "canohost.h"
	47	#include "buffer.h"
	48	#include "bufaux.h"
	49	#include "uidswap.h"
	50	#include "tildexpand.h"
b8d1a091	51	#include "misc.h"
	52	#include "bufaux.h"
	53	#include "packet.h"
3c0ef626	54
	55	/* import */
	56	extern ServerOptions options;
7cac2b65	57	extern Buffer loginmsg;
3c0ef626	58
b8d1a091	59	/* Debugging messages */
	60	Buffer auth_debug;
	61	int auth_debug_init;
	62
3c0ef626	63	/*
	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.
	69	* If the user's shell is not executable, false will be returned.
	70	* Otherwise true is returned.
	71	*/
	72	int
	73	allowed_user(struct passwd * pw)
	74	{
	75	struct stat st;
7cac2b65	76	const char hostname = NULL, ipaddr = NULL, *passwd = NULL;
3c0ef626	77	char *shell;
3c0ef626	78	int i;
7cac2b65	79	#if defined(HAVE_SHADOW_H) && !defined(DISABLE_SHADOW)
7cac2b65	80	struct spwd *spw = NULL;
bfe49944	81	#endif
3c0ef626	82
	83	/* Shouldn't be called if pw is NULL, but better safe than sorry... */
	84	if (!pw \|\| !pw->pw_name)
	85	return 0;
	86
7cac2b65	87	#if defined(HAVE_SHADOW_H) && !defined(DISABLE_SHADOW)
	88	if (!options.use_pam)
	89	spw = getspnam(pw->pw_name);
	90	#ifdef HAS_SHADOW_EXPIRE
b8d1a091	91	#define DAY (24L * 60 * 60) /* 1 day in seconds */
7cac2b65	92	if (!options.use_pam && spw != NULL) {
	93	time_t today;
	94
bfe49944	95	today = time(NULL) / DAY;
b8d1a091	96	debug3("allowed_user: today %d sp_expire %d sp_lstchg %d"
	97	" sp_max %d", (int)today, (int)spw->sp_expire,
	98	(int)spw->sp_lstchg, (int)spw->sp_max);
	99
	100	/*
	101	* We assume account and password expiration occurs the
	102	* day after the day specified.
	103	*/
	104	if (spw->sp_expire != -1 && today > spw->sp_expire) {
7cac2b65	105	logit("Account %.100s has expired", pw->pw_name);
b8d1a091	106	return 0;
b8d1a091	107	}
3c0ef626	108
b8d1a091	109	if (spw->sp_lstchg == 0) {
7cac2b65	110	logit("User %.100s password has expired (root forced)",
b8d1a091	111	pw->pw_name);
3c0ef626	112	return 0;
b8d1a091	113	}
3c0ef626	114
b8d1a091	115	if (spw->sp_max != -1 &&
b8d1a091	116	today > spw->sp_lstchg + spw->sp_max) {
7cac2b65	117	logit("User %.100s password has expired (password aged)",
b8d1a091	118	pw->pw_name);
3c0ef626	119	return 0;
b8d1a091	120	}
3c0ef626	121	}
7cac2b65	122	#endif /* HAS_SHADOW_EXPIRE */
	123	#endif /* defined(HAVE_SHADOW_H) && !defined(DISABLE_SHADOW) */
	124
	125	/* grab passwd field for locked account check */
	126	#if defined(HAVE_SHADOW_H) && !defined(DISABLE_SHADOW)
	127	if (spw != NULL)
	128	passwd = spw->sp_pwdp;
	129	#else
	130	passwd = pw->pw_passwd;
3c0ef626	131	#endif
3c0ef626	132
7cac2b65	133	/* check for locked account */
	134	if (!options.use_pam && passwd && *passwd) {
	135	int locked = 0;
	136
	137	#ifdef LOCKED_PASSWD_STRING
	138	if (strcmp(passwd, LOCKED_PASSWD_STRING) == 0)
	139	locked = 1;
	140	#endif
	141	#ifdef LOCKED_PASSWD_PREFIX
	142	if (strncmp(passwd, LOCKED_PASSWD_PREFIX,
	143	strlen(LOCKED_PASSWD_PREFIX)) == 0)
	144	locked = 1;
	145	#endif
	146	#ifdef LOCKED_PASSWD_SUBSTR
	147	if (strstr(passwd, LOCKED_PASSWD_SUBSTR))
	148	locked = 1;
	149	#endif
	150	if (locked) {
	151	logit("User %.100s not allowed because account is locked",
	152	pw->pw_name);
	153	return 0;
	154	}
	155	}
	156
3c0ef626	157	/*
	158	* Get the shell from the password data. An empty shell field is
	159	* legal, and means /bin/sh.
	160	*/
	161	shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;
	162
	163	/* deny if shell does not exists or is not executable */
b8d1a091	164	if (stat(shell, &st) != 0) {
7cac2b65	165	logit("User %.100s not allowed because shell %.100s does not exist",
b8d1a091	166	pw->pw_name, shell);
3c0ef626	167	return 0;
b8d1a091	168	}
	169	if (S_ISREG(st.st_mode) == 0 \|\|
	170	(st.st_mode & (S_IXOTH\|S_IXUSR\|S_IXGRP)) == 0) {
7cac2b65	171	logit("User %.100s not allowed because shell %.100s is not executable",
b8d1a091	172	pw->pw_name, shell);
3c0ef626	173	return 0;
b8d1a091	174	}
3c0ef626	175
3c0ef626	176	if (options.num_deny_users > 0 \|\| options.num_allow_users > 0) {
7cac2b65	177	hostname = get_canonical_hostname(options.use_dns);
3c0ef626	178	ipaddr = get_remote_ipaddr();
	179	}
	180
	181	/* Return false if user is listed in DenyUsers */
	182	if (options.num_deny_users > 0) {
	183	for (i = 0; i < options.num_deny_users; i++)
	184	if (match_user(pw->pw_name, hostname, ipaddr,
b8d1a091	185	options.deny_users[i])) {
7cac2b65	186	logit("User %.100s not allowed because listed in DenyUsers",
b8d1a091	187	pw->pw_name);
3c0ef626	188	return 0;
b8d1a091	189	}
3c0ef626	190	}
	191	/* Return false if AllowUsers isn't empty and user isn't listed there */
	192	if (options.num_allow_users > 0) {
	193	for (i = 0; i < options.num_allow_users; i++)
	194	if (match_user(pw->pw_name, hostname, ipaddr,
	195	options.allow_users[i]))
	196	break;
	197	/* i < options.num_allow_users iff we break for loop */
b8d1a091	198	if (i >= options.num_allow_users) {
7cac2b65	199	logit("User %.100s not allowed because not listed in AllowUsers",
b8d1a091	200	pw->pw_name);
3c0ef626	201	return 0;
b8d1a091	202	}
3c0ef626	203	}
	204	if (options.num_deny_groups > 0 \|\| options.num_allow_groups > 0) {
	205	/* Get the user's group access list (primary and supplementary) */
b8d1a091	206	if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
7cac2b65	207	logit("User %.100s not allowed because not in any group",
b8d1a091	208	pw->pw_name);
3c0ef626	209	return 0;
b8d1a091	210	}
3c0ef626	211
	212	/* Return false if one of user's groups is listed in DenyGroups */
	213	if (options.num_deny_groups > 0)
	214	if (ga_match(options.deny_groups,
	215	options.num_deny_groups)) {
	216	ga_free();
7cac2b65	217	logit("User %.100s not allowed because a group is listed in DenyGroups",
b8d1a091	218	pw->pw_name);
3c0ef626	219	return 0;
	220	}
	221	/*
	222	* Return false if AllowGroups isn't empty and one of user's groups
	223	* isn't listed there
	224	*/
	225	if (options.num_allow_groups > 0)
	226	if (!ga_match(options.allow_groups,
	227	options.num_allow_groups)) {
	228	ga_free();
7cac2b65	229	logit("User %.100s not allowed because none of user's groups are listed in AllowGroups",
b8d1a091	230	pw->pw_name);
3c0ef626	231	return 0;
	232	}
	233	ga_free();
	234	}
	235
	236	#ifdef WITH_AIXAUTHENTICATE
bfe49944	237	/*
	238	* Don't check loginrestrictions() for root account (use
	239	* PermitRootLogin to control logins via ssh), or if running as
	240	* non-root user (since loginrestrictions will always fail).
	241	*/
7cac2b65	242	if ((pw->pw_uid != 0) && (geteuid() == 0)) {
	243	char *msg;
	244
	245	if (loginrestrictions(pw->pw_name, S_RLOGIN, NULL, &msg) != 0) {
	246	int loginrestrict_errno = errno;
	247
	248	if (msg && *msg) {
	249	buffer_append(&loginmsg, msg, strlen(msg));
	250	aix_remove_embedded_newlines(msg);
	251	logit("Login restricted for %s: %.100s",
	252	pw->pw_name, msg);
3c0ef626	253	}
7cac2b65	254	/* Don't fail if /etc/nologin set */
	255	if (!(loginrestrict_errno == EPERM &&
	256	stat(_PATH_NOLOGIN, &st) == 0))
	257	return 0;
3c0ef626	258	}
3c0ef626	259	}
	260	#endif /* WITH_AIXAUTHENTICATE */
	261
	262	/* We found no reason not to let this user try to log on... */
	263	return 1;
	264	}
	265
	266	Authctxt *
	267	authctxt_new(void)
	268	{
	269	Authctxt authctxt = xmalloc(sizeof(authctxt));
	270	memset(authctxt, 0, sizeof(*authctxt));
	271	return authctxt;
	272	}
	273
	274	void
	275	auth_log(Authctxt authctxt, int authenticated, char method, char *info)
	276	{
	277	void (authlog) (const char fmt,...) = verbose;
	278	char *authmsg;
	279
	280	/* Raise logging level */
	281	if (authenticated == 1 \|\|
	282	!authctxt->valid \|\|
	283	authctxt->failures >= AUTH_FAIL_LOG \|\|
	284	strcmp(method, "password") == 0)
7cac2b65	285	authlog = logit;
3c0ef626	286
	287	if (authctxt->postponed)
	288	authmsg = "Postponed";
	289	else
	290	authmsg = authenticated ? "Accepted" : "Failed";
	291
	292	authlog("%s %s for %s%.100s from %.200s port %d%s",
	293	authmsg,
	294	method,
	295	authctxt->valid ? "" : "illegal user ",
b8d1a091	296	(authctxt->user[0]) ? authctxt->user : "<implicit>",
3c0ef626	297	get_remote_ipaddr(),
	298	get_remote_port(),
	299	info);
d03f4262	300
7cac2b65	301	#ifdef CUSTOM_FAILED_LOGIN
d03f4262	302	if (authenticated == 0 && strcmp(method, "password") == 0)
7cac2b65	303	record_failed_login(authctxt->user, "ssh");
7cac2b65	304	#endif
3c0ef626	305	}
	306
	307	/*
	308	* Check whether root logins are disallowed.
	309	*/
	310	int
	311	auth_root_allowed(char *method)
	312	{
	313	switch (options.permit_root_login) {
	314	case PERMIT_YES:
	315	return 1;
	316	break;
	317	case PERMIT_NO_PASSWD:
	318	if (strcmp(method, "password") != 0)
	319	return 1;
	320	break;
	321	case PERMIT_FORCED_ONLY:
	322	if (forced_command) {
7cac2b65	323	logit("Root login accepted for forced command.");
3c0ef626	324	return 1;
	325	}
	326	break;
	327	}
7cac2b65	328	logit("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
3c0ef626	329	return 0;
	330	}
	331
	332
	333	/*
	334	* Given a template and a passwd structure, build a filename
	335	* by substituting % tokenised options. Currently, %% becomes '%',
	336	* %h becomes the home directory and %u the username.
	337	*
	338	* This returns a buffer allocated by xmalloc.
	339	*/
	340	char *
	341	expand_filename(const char filename, struct passwd pw)
	342	{
	343	Buffer buffer;
	344	char *file;
	345	const char *cp;
	346
	347	/*
	348	* Build the filename string in the buffer by making the appropriate
	349	* substitutions to the given file name.
	350	*/
	351	buffer_init(&buffer);
	352	for (cp = filename; *cp; cp++) {
	353	if (cp[0] == '%' && cp[1] == '%') {
	354	buffer_append(&buffer, "%", 1);
	355	cp++;
	356	continue;
	357	}
	358	if (cp[0] == '%' && cp[1] == 'h') {
	359	buffer_append(&buffer, pw->pw_dir, strlen(pw->pw_dir));
	360	cp++;
	361	continue;
	362	}
	363	if (cp[0] == '%' && cp[1] == 'u') {
	364	buffer_append(&buffer, pw->pw_name,
b8d1a091	365	strlen(pw->pw_name));
3c0ef626	366	cp++;
	367	continue;
	368	}
	369	buffer_append(&buffer, cp, 1);
	370	}
	371	buffer_append(&buffer, "\0", 1);
	372
	373	/*
	374	* Ensure that filename starts anchored. If not, be backward
	375	* compatible and prepend the '%h/'
	376	*/
	377	file = xmalloc(MAXPATHLEN);
	378	cp = buffer_ptr(&buffer);
	379	if (*cp != '/')
	380	snprintf(file, MAXPATHLEN, "%s/%s", pw->pw_dir, cp);
	381	else
	382	strlcpy(file, cp, MAXPATHLEN);
	383
	384	buffer_free(&buffer);
	385	return file;
	386	}
	387
	388	char *
	389	authorized_keys_file(struct passwd *pw)
	390	{
	391	return expand_filename(options.authorized_keys_file, pw);
	392	}
	393
	394	char *
	395	authorized_keys_file2(struct passwd *pw)
	396	{
	397	return expand_filename(options.authorized_keys_file2, pw);
	398	}
	399
	400	/* return ok if key exists in sysfile or userfile */
	401	HostStatus
	402	check_key_in_hostfiles(struct passwd pw, Key key, const char *host,
	403	const char sysfile, const char userfile)
	404	{
	405	Key *found;
	406	char *user_hostfile;
	407	struct stat st;
b8d1a091	408	HostStatus host_status;
3c0ef626	409
	410	/* Check if we know the host and its host key. */
	411	found = key_new(key->type);
	412	host_status = check_host_in_hostfile(sysfile, host, key, found, NULL);
	413
	414	if (host_status != HOST_OK && userfile != NULL) {
	415	user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
	416	if (options.strict_modes &&
	417	(stat(user_hostfile, &st) == 0) &&
	418	((st.st_uid != 0 && st.st_uid != pw->pw_uid) \|\|
b8d1a091	419	(st.st_mode & 022) != 0)) {
7cac2b65	420	logit("Authentication refused for %.100s: "
3c0ef626	421	"bad owner or modes for %.200s",
	422	pw->pw_name, user_hostfile);
	423	} else {
	424	temporarily_use_uid(pw);
	425	host_status = check_host_in_hostfile(user_hostfile,
	426	host, key, found, NULL);
	427	restore_uid();
	428	}
	429	xfree(user_hostfile);
	430	}
	431	key_free(found);
	432
	433	debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ?
	434	"ok" : "not found", host);
	435	return host_status;
	436	}
	437
	438
	439	/*
	440	* Check a given file for security. This is defined as all components
d03f4262	441	* of the path to the file must be owned by either the owner of
3c0ef626	442	* of the file or root and no directories must be group or world writable.
	443	*
	444	* XXX Should any specific check be done for sym links ?
	445	*
	446	* Takes an open file descriptor, the file name, a uid and and
	447	* error buffer plus max size as arguments.
	448	*
	449	* Returns 0 on success and -1 on failure
	450	*/
	451	int
	452	secure_filename(FILE f, const char file, struct passwd *pw,
	453	char *err, size_t errlen)
	454	{
	455	uid_t uid = pw->pw_uid;
	456	char buf[MAXPATHLEN], homedir[MAXPATHLEN];
	457	char *cp;
bfe49944	458	int comparehome = 0;
3c0ef626	459	struct stat st;
	460
	461	if (realpath(file, buf) == NULL) {
	462	snprintf(err, errlen, "realpath %s failed: %s", file,
	463	strerror(errno));
	464	return -1;
	465	}
bfe49944	466	if (realpath(pw->pw_dir, homedir) != NULL)
bfe49944	467	comparehome = 1;
3c0ef626	468
	469	/* check the open file to avoid races */
	470	if (fstat(fileno(f), &st) < 0 \|\|
	471	(st.st_uid != 0 && st.st_uid != uid) \|\|
	472	(st.st_mode & 022) != 0) {
	473	snprintf(err, errlen, "bad ownership or modes for file %s",
	474	buf);
	475	return -1;
	476	}
	477
	478	/* for each component of the canonical path, walking upwards */
	479	for (;;) {
	480	if ((cp = dirname(buf)) == NULL) {
	481	snprintf(err, errlen, "dirname() failed");
	482	return -1;
	483	}
	484	strlcpy(buf, cp, sizeof(buf));
	485
	486	debug3("secure_filename: checking '%s'", buf);
	487	if (stat(buf, &st) < 0 \|\|
	488	(st.st_uid != 0 && st.st_uid != uid) \|\|
	489	(st.st_mode & 022) != 0) {
b8d1a091	490	snprintf(err, errlen,
3c0ef626	491	"bad ownership or modes for directory %s", buf);
	492	return -1;
	493	}
	494
	495	/* If are passed the homedir then we can stop */
bfe49944	496	if (comparehome && strcmp(homedir, buf) == 0) {
3c0ef626	497	debug3("secure_filename: terminating check at '%s'",
	498	buf);
	499	break;
	500	}
	501	/*
	502	* dirname should always complete with a "/" path,
	503	* but we can be paranoid and check for "." too
	504	*/
	505	if ((strcmp("/", buf) == 0) \|\| (strcmp(".", buf) == 0))
	506	break;
	507	}
	508	return 0;
	509	}
b8d1a091	510
	511	struct passwd *
	512	getpwnamallow(const char *user)
	513	{
	514	#ifdef HAVE_LOGIN_CAP
	515	extern login_cap_t *lc;
	516	#ifdef BSD_AUTH
	517	auth_session_t *as;
	518	#endif
	519	#endif
	520	struct passwd *pw;
	521
	522	pw = getpwnam(user);
d03f4262	523	if (pw == NULL) {
7cac2b65	524	logit("Illegal user %.100s from %.100s",
5885a49e	525	(user && user[0]) ? user : "<implicit>",
5885a49e	526	get_remote_ipaddr());
7cac2b65	527	#ifdef CUSTOM_FAILED_LOGIN
7cac2b65	528	record_failed_login(user, "ssh");
bfe49944	529	#endif
d03f4262	530	return (NULL);
	531	}
	532	if (!allowed_user(pw))
b8d1a091	533	return (NULL);
	534	#ifdef HAVE_LOGIN_CAP
	535	if ((lc = login_getclass(pw->pw_class)) == NULL) {
	536	debug("unable to get login class: %s", user);
	537	return (NULL);
	538	}
	539	#ifdef BSD_AUTH
	540	if ((as = auth_open()) == NULL \|\| auth_setpwd(as, pw) != 0 \|\|
	541	auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
	542	debug("Approval failure for %s", user);
	543	pw = NULL;
	544	}
	545	if (as != NULL)
	546	auth_close(as);
	547	#endif
	548	#endif
	549	if (pw != NULL)
	550	return (pwcopy(pw));
	551	return (NULL);
	552	}
	553
	554	void
	555	auth_debug_add(const char *fmt,...)
	556	{
	557	char buf[1024];
	558	va_list args;
	559
	560	if (!auth_debug_init)
	561	return;
	562
	563	va_start(args, fmt);
	564	vsnprintf(buf, sizeof(buf), fmt, args);
	565	va_end(args);
	566	buffer_put_cstring(&auth_debug, buf);
	567	}
	568
	569	void
	570	auth_debug_send(void)
	571	{
	572	char *msg;
	573
	574	if (!auth_debug_init)
	575	return;
	576	while (buffer_len(&auth_debug)) {
	577	msg = buffer_get_string(&auth_debug, NULL);
	578	packet_send_debug("%s", msg);
	579	xfree(msg);
	580	}
	581	}
	582
	583	void
	584	auth_debug_reset(void)
	585	{
	586	if (auth_debug_init)
	587	buffer_clear(&auth_debug);
	588	else {
	589	buffer_init(&auth_debug);
	590	auth_debug_init = 1;
	591	}
	592	}
7cac2b65	593
	594	struct passwd *
	595	fakepw(void)
	596	{
	597	static struct passwd fake;
	598
	599	memset(&fake, 0, sizeof(fake));
	600	fake.pw_name = "NOUSER";
	601	fake.pw_passwd =
	602	"$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK";
	603	fake.pw_gecos = "NOUSER";
	604	fake.pw_uid = -1;
	605	fake.pw_gid = -1;
	606	#ifdef HAVE_PW_CLASS_IN_PASSWD
	607	fake.pw_class = "";
	608	#endif
	609	fake.pw_dir = "/nonexist";
	610	fake.pw_shell = "/nonexist";
	611
	612	return (&fake);
	613	}