[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 1.46 2002/11/04 10:07:53 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;

/* 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;
	char *shell;
	int i;
#ifdef WITH_AIXAUTHENTICATE
	char *loginmsg;
#endif /* WITH_AIXAUTHENTICATE */
#if !defined(USE_PAM) && defined(HAVE_SHADOW_H) && \
    !defined(DISABLE_SHADOW) && defined(HAS_SHADOW_EXPIRE)
	struct spwd *spw;
	time_t today;
#endif

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

#if !defined(USE_PAM) && defined(HAVE_SHADOW_H) && \
    !defined(DISABLE_SHADOW) && defined(HAS_SHADOW_EXPIRE)
#define	DAY		(24L * 60 * 60) /* 1 day in seconds */
	if ((spw = getspnam(pw->pw_name)) != NULL) {
		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) {
			log("Account %.100s has expired", pw->pw_name);
			return 0;
		}

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

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

	/*
	 * Get the shell from the password data.  An empty shell field is
	 * legal, and means /bin/sh.
	 */
	shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;

	/* deny if shell does not exists or is not executable */
	if (stat(shell, &st) != 0) {
		log("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) {
		log("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.verify_reverse_mapping);
		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])) {
				log("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) {
			log("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) {
			log("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();
				log("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();
				log("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) &&
	    loginrestrictions(pw->pw_name, S_RLOGIN, NULL, &loginmsg) != 0) {
		int loginrestrict_errno = errno;

		if (loginmsg && *loginmsg) {
			/* Remove embedded newlines (if any) */
			char *p;
			for (p = loginmsg; *p; p++) {
				if (*p == '\n')
					*p = ' ';
			}
			/* Remove trailing newline */
			*--p = '\0';
			log("Login restricted for %s: %.100s", pw->pw_name, 
			    loginmsg);
		}
		/* 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 = log;

	if (authctxt->postponed)
		authmsg = "Postponed";
	else
		authmsg = authenticated ? "Accepted" : "Failed";

	authlog("%s %s for %s%.100s from %.200s port %d%s",
	    authmsg,
	    method,
	    authctxt->valid ? "" : "illegal user ",
	    (authctxt->user[0]) ? authctxt->user : "<implicit>",
	    get_remote_ipaddr(),
	    get_remote_port(),
	    info);

#ifdef WITH_AIXAUTHENTICATE
	if (authenticated == 0 && strcmp(method, "password") == 0)
	    loginfailed(authctxt->user,
		get_canonical_hostname(options.verify_reverse_mapping),
		"ssh");
#endif /* WITH_AIXAUTHENTICATE */

}

/*
 * Check whether root logins are disallowed.
 */
int
auth_root_allowed(char *method)
{
	switch (options.permit_root_login) {
	case PERMIT_YES:
		return 1;
		break;
	case PERMIT_NO_PASSWD:
		if (strcmp(method, "password") != 0)
			return 1;
		break;
	case PERMIT_FORCED_ONLY:
		if (forced_command) {
			log("Root login accepted for forced command.");
			return 1;
		}
		break;
	}
	log("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
	return 0;
}


/*
 * Given a template and a passwd structure, build a filename
 * by substituting % tokenised options. Currently, %% becomes '%',
 * %h becomes the home directory and %u the username.
 *
 * This returns a buffer allocated by xmalloc.
 */
char *
expand_filename(const char *filename, struct passwd *pw)
{
	Buffer buffer;
	char *file;
	const char *cp;

	/*
	 * Build the filename string in the buffer by making the appropriate
	 * substitutions to the given file name.
	 */
	buffer_init(&buffer);
	for (cp = filename; *cp; cp++) {
		if (cp[0] == '%' && cp[1] == '%') {
			buffer_append(&buffer, "%", 1);
			cp++;
			continue;
		}
		if (cp[0] == '%' && cp[1] == 'h') {
			buffer_append(&buffer, pw->pw_dir, strlen(pw->pw_dir));
			cp++;
			continue;
		}
		if (cp[0] == '%' && cp[1] == 'u') {
			buffer_append(&buffer, pw->pw_name,
			    strlen(pw->pw_name));
			cp++;
			continue;
		}
		buffer_append(&buffer, cp, 1);
	}
	buffer_append(&buffer, "\0", 1);

	/*
	 * Ensure that filename starts anchored. If not, be backward
	 * compatible and prepend the '%h/'
	 */
	file = xmalloc(MAXPATHLEN);
	cp = buffer_ptr(&buffer);
	if (*cp != '/')
		snprintf(file, MAXPATHLEN, "%s/%s", pw->pw_dir, cp);
	else
		strlcpy(file, cp, MAXPATHLEN);

	buffer_free(&buffer);
	return file;
}

char *
authorized_keys_file(struct passwd *pw)
{
	return expand_filename(options.authorized_keys_file, pw);
}

char *
authorized_keys_file2(struct passwd *pw)
{
	return expand_filename(options.authorized_keys_file2, pw);
}

/* return ok if key exists in sysfile or userfile */
HostStatus
check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host,
    const char *sysfile, const char *userfile)
{
	Key *found;
	char *user_hostfile;
	struct stat st;
	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)) {
			log("Authentication refused for %.100s: "
			    "bad owner or modes for %.200s",
			    pw->pw_name, user_hostfile);
		} else {
			temporarily_use_uid(pw);
			host_status = check_host_in_hostfile(user_hostfile,
			    host, key, found, NULL);
			restore_uid();
		}
		xfree(user_hostfile);
	}
	key_free(found);

	debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ?
	    "ok" : "not found", host);
	return host_status;
}


/*
 * Check a given file for security. This is defined as all components
 * of the path to the file must 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) {
		log("Illegal user %.100s from %.100s",
		    user, get_remote_ipaddr());
#ifdef WITH_AIXAUTHENTICATE
		loginfailed(user,
		    get_canonical_hostname(options.verify_reverse_mapping),
		    "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;
	}
}
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"
6a9b3198	26	RCSID("$OpenBSD: auth.c,v 1.46 2002/11/04 10:07:53 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"
700318f3	51	#include "misc.h"
	52	#include "bufaux.h"
	53	#include "packet.h"
3c0ef626	54
	55	/* import */
	56	extern ServerOptions options;
	57
700318f3	58	/* Debugging messages */
	59	Buffer auth_debug;
	60	int auth_debug_init;
	61
3c0ef626	62	/*
	63	* Check if the user is allowed to log in via ssh. If user is listed
	64	* in DenyUsers or one of user's groups is listed in DenyGroups, false
	65	* will be returned. If AllowUsers isn't empty and user isn't listed
	66	* there, or if AllowGroups isn't empty and one of user's groups isn't
	67	* listed there, false will be returned.
	68	* If the user's shell is not executable, false will be returned.
	69	* Otherwise true is returned.
	70	*/
	71	int
	72	allowed_user(struct passwd * pw)
	73	{
	74	struct stat st;
	75	const char hostname = NULL, ipaddr = NULL;
	76	char *shell;
	77	int i;
	78	#ifdef WITH_AIXAUTHENTICATE
	79	char *loginmsg;
	80	#endif /* WITH_AIXAUTHENTICATE */
	81	#if !defined(USE_PAM) && defined(HAVE_SHADOW_H) && \
6a9b3198	82	!defined(DISABLE_SHADOW) && defined(HAS_SHADOW_EXPIRE)
3c0ef626	83	struct spwd *spw;
6a9b3198	84	time_t today;
6a9b3198	85	#endif
3c0ef626	86
	87	/* Shouldn't be called if pw is NULL, but better safe than sorry... */
	88	if (!pw \|\| !pw->pw_name)
	89	return 0;
	90
6a9b3198	91	#if !defined(USE_PAM) && defined(HAVE_SHADOW_H) && \
6a9b3198	92	!defined(DISABLE_SHADOW) && defined(HAS_SHADOW_EXPIRE)
700318f3	93	#define DAY (24L * 60 * 60) /* 1 day in seconds */
6a9b3198	94	if ((spw = getspnam(pw->pw_name)) != NULL) {
6a9b3198	95	today = time(NULL) / DAY;
700318f3	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) {
	105	log("Account %.100s has expired", pw->pw_name);
	106	return 0;
	107	}
3c0ef626	108
700318f3	109	if (spw->sp_lstchg == 0) {
	110	log("User %.100s password has expired (root forced)",
	111	pw->pw_name);
3c0ef626	112	return 0;
700318f3	113	}
3c0ef626	114
700318f3	115	if (spw->sp_max != -1 &&
	116	today > spw->sp_lstchg + spw->sp_max) {
	117	log("User %.100s password has expired (password aged)",
	118	pw->pw_name);
3c0ef626	119	return 0;
700318f3	120	}
3c0ef626	121	}
3c0ef626	122	#endif
	123
	124	/*
	125	* Get the shell from the password data. An empty shell field is
	126	* legal, and means /bin/sh.
	127	*/
	128	shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;
	129
	130	/* deny if shell does not exists or is not executable */
e9a17296	131	if (stat(shell, &st) != 0) {
	132	log("User %.100s not allowed because shell %.100s does not exist",
	133	pw->pw_name, shell);
3c0ef626	134	return 0;
e9a17296	135	}
700318f3	136	if (S_ISREG(st.st_mode) == 0 \|\|
700318f3	137	(st.st_mode & (S_IXOTH\|S_IXUSR\|S_IXGRP)) == 0) {
e9a17296	138	log("User %.100s not allowed because shell %.100s is not executable",
e9a17296	139	pw->pw_name, shell);
3c0ef626	140	return 0;
e9a17296	141	}
3c0ef626	142
3c0ef626	143	if (options.num_deny_users > 0 \|\| options.num_allow_users > 0) {
e9a17296	144	hostname = get_canonical_hostname(options.verify_reverse_mapping);
3c0ef626	145	ipaddr = get_remote_ipaddr();
	146	}
	147
	148	/* Return false if user is listed in DenyUsers */
	149	if (options.num_deny_users > 0) {
	150	for (i = 0; i < options.num_deny_users; i++)
700318f3	151	if (match_user(pw->pw_name, hostname, ipaddr,
e9a17296	152	options.deny_users[i])) {
700318f3	153	log("User %.100s not allowed because listed in DenyUsers",
700318f3	154	pw->pw_name);
3c0ef626	155	return 0;
e9a17296	156	}
3c0ef626	157	}
	158	/* Return false if AllowUsers isn't empty and user isn't listed there */
	159	if (options.num_allow_users > 0) {
	160	for (i = 0; i < options.num_allow_users; i++)
700318f3	161	if (match_user(pw->pw_name, hostname, ipaddr,
3c0ef626	162	options.allow_users[i]))
	163	break;
	164	/* i < options.num_allow_users iff we break for loop */
e9a17296	165	if (i >= options.num_allow_users) {
	166	log("User %.100s not allowed because not listed in AllowUsers",
	167	pw->pw_name);
3c0ef626	168	return 0;
e9a17296	169	}
3c0ef626	170	}
	171	if (options.num_deny_groups > 0 \|\| options.num_allow_groups > 0) {
	172	/* Get the user's group access list (primary and supplementary) */
e9a17296	173	if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
	174	log("User %.100s not allowed because not in any group",
	175	pw->pw_name);
3c0ef626	176	return 0;
e9a17296	177	}
3c0ef626	178
	179	/* Return false if one of user's groups is listed in DenyGroups */
	180	if (options.num_deny_groups > 0)
	181	if (ga_match(options.deny_groups,
	182	options.num_deny_groups)) {
	183	ga_free();
e9a17296	184	log("User %.100s not allowed because a group is listed in DenyGroups",
e9a17296	185	pw->pw_name);
3c0ef626	186	return 0;
	187	}
	188	/*
	189	* Return false if AllowGroups isn't empty and one of user's groups
	190	* isn't listed there
	191	*/
	192	if (options.num_allow_groups > 0)
	193	if (!ga_match(options.allow_groups,
	194	options.num_allow_groups)) {
	195	ga_free();
e9a17296	196	log("User %.100s not allowed because none of user's groups are listed in AllowGroups",
e9a17296	197	pw->pw_name);
3c0ef626	198	return 0;
	199	}
	200	ga_free();
	201	}
	202
	203	#ifdef WITH_AIXAUTHENTICATE
6a9b3198	204	/*
	205	* Don't check loginrestrictions() for root account (use
	206	* PermitRootLogin to control logins via ssh), or if running as
	207	* non-root user (since loginrestrictions will always fail).
	208	*/
	209	if ((pw->pw_uid != 0) && (geteuid() == 0) &&
	210	loginrestrictions(pw->pw_name, S_RLOGIN, NULL, &loginmsg) != 0) {
	211	int loginrestrict_errno = errno;
	212
3c0ef626	213	if (loginmsg && *loginmsg) {
	214	/* Remove embedded newlines (if any) */
	215	char *p;
	216	for (p = loginmsg; *p; p++) {
	217	if (*p == '\n')
	218	*p = ' ';
	219	}
	220	/* Remove trailing newline */
	221	*--p = '\0';
6a9b3198	222	log("Login restricted for %s: %.100s", pw->pw_name,
6a9b3198	223	loginmsg);
3c0ef626	224	}
6a9b3198	225	/* Don't fail if /etc/nologin set */
	226	if (!(loginrestrict_errno == EPERM &&
	227	stat(_PATH_NOLOGIN, &st) == 0))
	228	return 0;
3c0ef626	229	}
	230	#endif /* WITH_AIXAUTHENTICATE */
	231
	232	/* We found no reason not to let this user try to log on... */
	233	return 1;
	234	}
	235
	236	Authctxt *
	237	authctxt_new(void)
	238	{
	239	Authctxt authctxt = xmalloc(sizeof(authctxt));
	240	memset(authctxt, 0, sizeof(*authctxt));
	241	return authctxt;
	242	}
	243
	244	void
	245	auth_log(Authctxt authctxt, int authenticated, char method, char *info)
	246	{
	247	void (authlog) (const char fmt,...) = verbose;
	248	char *authmsg;
	249
	250	/* Raise logging level */
	251	if (authenticated == 1 \|\|
	252	!authctxt->valid \|\|
	253	authctxt->failures >= AUTH_FAIL_LOG \|\|
	254	strcmp(method, "password") == 0)
	255	authlog = log;
	256
	257	if (authctxt->postponed)
	258	authmsg = "Postponed";
	259	else
	260	authmsg = authenticated ? "Accepted" : "Failed";
	261
	262	authlog("%s %s for %s%.100s from %.200s port %d%s",
	263	authmsg,
	264	method,
	265	authctxt->valid ? "" : "illegal user ",
c0fc5818	266	(authctxt->user[0]) ? authctxt->user : "<implicit>",
3c0ef626	267	get_remote_ipaddr(),
	268	get_remote_port(),
	269	info);
41b2f314	270
	271	#ifdef WITH_AIXAUTHENTICATE
	272	if (authenticated == 0 && strcmp(method, "password") == 0)
	273	loginfailed(authctxt->user,
	274	get_canonical_hostname(options.verify_reverse_mapping),
	275	"ssh");
	276	#endif /* WITH_AIXAUTHENTICATE */
	277
3c0ef626	278	}
	279
	280	/*
	281	* Check whether root logins are disallowed.
	282	*/
	283	int
	284	auth_root_allowed(char *method)
	285	{
	286	switch (options.permit_root_login) {
	287	case PERMIT_YES:
	288	return 1;
	289	break;
	290	case PERMIT_NO_PASSWD:
	291	if (strcmp(method, "password") != 0)
	292	return 1;
	293	break;
	294	case PERMIT_FORCED_ONLY:
	295	if (forced_command) {
	296	log("Root login accepted for forced command.");
	297	return 1;
	298	}
	299	break;
	300	}
	301	log("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
	302	return 0;
	303	}
	304
	305
	306	/*
	307	* Given a template and a passwd structure, build a filename
	308	* by substituting % tokenised options. Currently, %% becomes '%',
	309	* %h becomes the home directory and %u the username.
	310	*
	311	* This returns a buffer allocated by xmalloc.
	312	*/
	313	char *
	314	expand_filename(const char filename, struct passwd pw)
	315	{
	316	Buffer buffer;
	317	char *file;
	318	const char *cp;
	319
	320	/*
	321	* Build the filename string in the buffer by making the appropriate
	322	* substitutions to the given file name.
	323	*/
	324	buffer_init(&buffer);
	325	for (cp = filename; *cp; cp++) {
	326	if (cp[0] == '%' && cp[1] == '%') {
	327	buffer_append(&buffer, "%", 1);
	328	cp++;
	329	continue;
	330	}
	331	if (cp[0] == '%' && cp[1] == 'h') {
	332	buffer_append(&buffer, pw->pw_dir, strlen(pw->pw_dir));
	333	cp++;
	334	continue;
	335	}
	336	if (cp[0] == '%' && cp[1] == 'u') {
	337	buffer_append(&buffer, pw->pw_name,
e9a17296	338	strlen(pw->pw_name));
3c0ef626	339	cp++;
	340	continue;
	341	}
	342	buffer_append(&buffer, cp, 1);
	343	}
	344	buffer_append(&buffer, "\0", 1);
	345
	346	/*
	347	* Ensure that filename starts anchored. If not, be backward
	348	* compatible and prepend the '%h/'
	349	*/
	350	file = xmalloc(MAXPATHLEN);
	351	cp = buffer_ptr(&buffer);
	352	if (*cp != '/')
	353	snprintf(file, MAXPATHLEN, "%s/%s", pw->pw_dir, cp);
	354	else
	355	strlcpy(file, cp, MAXPATHLEN);
	356
	357	buffer_free(&buffer);
	358	return file;
	359	}
	360
	361	char *
	362	authorized_keys_file(struct passwd *pw)
	363	{
	364	return expand_filename(options.authorized_keys_file, pw);
	365	}
	366
	367	char *
	368	authorized_keys_file2(struct passwd *pw)
	369	{
	370	return expand_filename(options.authorized_keys_file2, pw);
	371	}
	372
	373	/* return ok if key exists in sysfile or userfile */
	374	HostStatus
	375	check_key_in_hostfiles(struct passwd pw, Key key, const char *host,
	376	const char sysfile, const char userfile)
	377	{
	378	Key *found;
	379	char *user_hostfile;
	380	struct stat st;
e9a17296	381	HostStatus host_status;
3c0ef626	382
	383	/* Check if we know the host and its host key. */
	384	found = key_new(key->type);
	385	host_status = check_host_in_hostfile(sysfile, host, key, found, NULL);
	386
	387	if (host_status != HOST_OK && userfile != NULL) {
	388	user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
	389	if (options.strict_modes &&
	390	(stat(user_hostfile, &st) == 0) &&
	391	((st.st_uid != 0 && st.st_uid != pw->pw_uid) \|\|
e9a17296	392	(st.st_mode & 022) != 0)) {
3c0ef626	393	log("Authentication refused for %.100s: "
	394	"bad owner or modes for %.200s",
	395	pw->pw_name, user_hostfile);
	396	} else {
	397	temporarily_use_uid(pw);
	398	host_status = check_host_in_hostfile(user_hostfile,
	399	host, key, found, NULL);
	400	restore_uid();
	401	}
	402	xfree(user_hostfile);
	403	}
	404	key_free(found);
	405
	406	debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ?
	407	"ok" : "not found", host);
	408	return host_status;
	409	}
	410
	411
	412	/*
	413	* Check a given file for security. This is defined as all components
41b2f314	414	* of the path to the file must be owned by either the owner of
3c0ef626	415	* of the file or root and no directories must be group or world writable.
	416	*
	417	* XXX Should any specific check be done for sym links ?
	418	*
	419	* Takes an open file descriptor, the file name, a uid and and
	420	* error buffer plus max size as arguments.
	421	*
	422	* Returns 0 on success and -1 on failure
	423	*/
	424	int
	425	secure_filename(FILE f, const char file, struct passwd *pw,
	426	char *err, size_t errlen)
	427	{
	428	uid_t uid = pw->pw_uid;
	429	char buf[MAXPATHLEN], homedir[MAXPATHLEN];
	430	char *cp;
6a9b3198	431	int comparehome = 0;
3c0ef626	432	struct stat st;
	433
	434	if (realpath(file, buf) == NULL) {
	435	snprintf(err, errlen, "realpath %s failed: %s", file,
	436	strerror(errno));
	437	return -1;
	438	}
6a9b3198	439	if (realpath(pw->pw_dir, homedir) != NULL)
6a9b3198	440	comparehome = 1;
3c0ef626	441
	442	/* check the open file to avoid races */
	443	if (fstat(fileno(f), &st) < 0 \|\|
	444	(st.st_uid != 0 && st.st_uid != uid) \|\|
	445	(st.st_mode & 022) != 0) {
	446	snprintf(err, errlen, "bad ownership or modes for file %s",
	447	buf);
	448	return -1;
	449	}
	450
	451	/* for each component of the canonical path, walking upwards */
	452	for (;;) {
	453	if ((cp = dirname(buf)) == NULL) {
	454	snprintf(err, errlen, "dirname() failed");
	455	return -1;
	456	}
	457	strlcpy(buf, cp, sizeof(buf));
	458
	459	debug3("secure_filename: checking '%s'", buf);
	460	if (stat(buf, &st) < 0 \|\|
	461	(st.st_uid != 0 && st.st_uid != uid) \|\|
	462	(st.st_mode & 022) != 0) {
e9a17296	463	snprintf(err, errlen,
3c0ef626	464	"bad ownership or modes for directory %s", buf);
	465	return -1;
	466	}
	467
	468	/* If are passed the homedir then we can stop */
6a9b3198	469	if (comparehome && strcmp(homedir, buf) == 0) {
3c0ef626	470	debug3("secure_filename: terminating check at '%s'",
	471	buf);
	472	break;
	473	}
	474	/*
	475	* dirname should always complete with a "/" path,
	476	* but we can be paranoid and check for "." too
	477	*/
	478	if ((strcmp("/", buf) == 0) \|\| (strcmp(".", buf) == 0))
	479	break;
	480	}
	481	return 0;
	482	}
700318f3	483
	484	struct passwd *
	485	getpwnamallow(const char *user)
	486	{
	487	#ifdef HAVE_LOGIN_CAP
	488	extern login_cap_t *lc;
	489	#ifdef BSD_AUTH
	490	auth_session_t *as;
	491	#endif
	492	#endif
	493	struct passwd *pw;
	494
	495	pw = getpwnam(user);
41b2f314	496	if (pw == NULL) {
	497	log("Illegal user %.100s from %.100s",
	498	user, get_remote_ipaddr());
6a9b3198	499	#ifdef WITH_AIXAUTHENTICATE
	500	loginfailed(user,
	501	get_canonical_hostname(options.verify_reverse_mapping),
	502	"ssh");
	503	#endif
41b2f314	504	return (NULL);
	505	}
	506	if (!allowed_user(pw))
700318f3	507	return (NULL);
	508	#ifdef HAVE_LOGIN_CAP
	509	if ((lc = login_getclass(pw->pw_class)) == NULL) {
	510	debug("unable to get login class: %s", user);
	511	return (NULL);
	512	}
	513	#ifdef BSD_AUTH
	514	if ((as = auth_open()) == NULL \|\| auth_setpwd(as, pw) != 0 \|\|
7435de97	515	auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
700318f3	516	debug("Approval failure for %s", user);
	517	pw = NULL;
	518	}
	519	if (as != NULL)
	520	auth_close(as);
	521	#endif
	522	#endif
	523	if (pw != NULL)
	524	return (pwcopy(pw));
	525	return (NULL);
	526	}
	527
	528	void
	529	auth_debug_add(const char *fmt,...)
	530	{
	531	char buf[1024];
	532	va_list args;
	533
	534	if (!auth_debug_init)
	535	return;
	536
	537	va_start(args, fmt);
	538	vsnprintf(buf, sizeof(buf), fmt, args);
	539	va_end(args);
	540	buffer_put_cstring(&auth_debug, buf);
	541	}
	542
	543	void
	544	auth_debug_send(void)
	545	{
	546	char *msg;
	547
	548	if (!auth_debug_init)
	549	return;
	550	while (buffer_len(&auth_debug)) {
	551	msg = buffer_get_string(&auth_debug, NULL);
	552	packet_send_debug("%s", msg);
	553	xfree(msg);
	554	}
	555	}
	556
	557	void
	558	auth_debug_reset(void)
	559	{
	560	if (auth_debug_init)
	561	buffer_clear(&auth_debug);
	562	else {
	563	buffer_init(&auth_debug);
	564	auth_debug_init = 1;
	565	}
	566	}