[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 1.57 2005/01/22 08:17:59 dtucker Exp $");

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

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

#include "xmalloc.h"
#include "match.h"
#include "groupaccess.h"
#include "log.h"
#include "servconf.h"
#include "auth.h"
#include "auth-options.h"
#include "canohost.h"
#include "buffer.h"
#include "bufaux.h"
#include "uidswap.h"
#include "misc.h"
#include "bufaux.h"
#include "packet.h"
#include "loginrec.h"
#include "monitor_wrap.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 from %.100s not allowed "
				    "because listed in DenyUsers",
				    pw->pw_name, hostname);
				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 from %.100s not allowed because "
			    "not listed in AllowUsers", pw->pw_name, hostname);
			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 from %.100s not allowed because "
			    "not in any group", pw->pw_name, hostname);
			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 from %.100s not allowed "
				    "because a group is listed in DenyGroups",
				    pw->pw_name, hostname);
				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 from %.100s not allowed "
				    "because none of user's groups are listed "
				    "in AllowGroups", pw->pw_name, hostname);
				return 0;
			}
		ga_free();
	}

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

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

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

	/* Raise logging level */
	if (authenticated == 1 ||
	    !authctxt->valid ||
	    authctxt->failures >= options.max_authtries / 2 ||
	    strcmp(method, "password") == 0)
		authlog = logit;

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

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

#ifdef CUSTOM_FAILED_LOGIN
	if (authenticated == 0 && !authctxt->postponed &&
	    (strcmp(method, "password") == 0 ||
	    strncmp(method, "keyboard-interactive", 20) == 0 ||
	    strcmp(method, "challenge-response") == 0))
		record_failed_login(authctxt->user,
		    get_canonical_hostname(options.use_dns), "ssh");
#endif
#ifdef SSH_AUDIT_EVENTS
	if (authenticated == 0 && !authctxt->postponed) {
		ssh_audit_event_t event;

		debug3("audit failed auth attempt, method %s euid %d",
		    method, (int)geteuid());
		/*
		 * Because the auth loop is used in both monitor and slave,
		 * we must be careful to send each event only once and with
		 * enough privs to write the event.
		 */
		event = audit_classify_auth(method);
		switch(event) {
		case SSH_AUTH_FAIL_NONE:
		case SSH_AUTH_FAIL_PASSWD:
		case SSH_AUTH_FAIL_KBDINT:
			if (geteuid() == 0)
				audit_event(event);
			break;
		case SSH_AUTH_FAIL_PUBKEY:
		case SSH_AUTH_FAIL_HOSTBASED:
		case SSH_AUTH_FAIL_GSSAPI:
			/*
			 * This is required to handle the case where privsep
			 * is enabled but it's root logging in, since
			 * use_privsep won't be cleared until after a
			 * successful login.
			 */
			if (geteuid() == 0)
				audit_event(event);
			else
				PRIVSEP(audit_event(event));
			break;
		default:
			error("unknown authentication audit event %d", event);
		}
	}
#endif
}

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


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

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

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

	buffer_free(&buffer);
	return file;
}

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

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

/* return ok if key exists in sysfile or userfile */
HostStatus
check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host,
    const char *sysfile, const char *userfile)
{
	Key *found;
	char *user_hostfile;
	struct stat st;
	HostStatus host_status;

	/* Check if we know the host and its host key. */
	found = key_new(key->type);
	host_status = check_host_in_hostfile(sysfile, host, key, found, NULL);

	if (host_status != HOST_OK && userfile != NULL) {
		user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
		if (options.strict_modes &&
		    (stat(user_hostfile, &st) == 0) &&
		    ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
		    (st.st_mode & 022) != 0)) {
			logit("Authentication refused for %.100s: "
			    "bad owner or modes for %.200s",
			    pw->pw_name, user_hostfile);
		} else {
			temporarily_use_uid(pw);
			host_status = check_host_in_hostfile(user_hostfile,
			    host, key, found, NULL);
			restore_uid();
		}
		xfree(user_hostfile);
	}
	key_free(found);

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


/*
 * Check a given file for security. This is defined as all components
 * of the path to the file must be owned by either the owner of
 * of the file or root and no directories must be group or world writable.
 *
 * XXX Should any specific check be done for sym links ?
 *
 * Takes an open file descriptor, the file name, a uid and and
 * error buffer plus max size as arguments.
 *
 * Returns 0 on success and -1 on failure
 */
int
secure_filename(FILE *f, const char *file, struct passwd *pw,
    char *err, size_t errlen)
{
	uid_t uid = pw->pw_uid;
	char buf[MAXPATHLEN], homedir[MAXPATHLEN];
	char *cp;
	int comparehome = 0;
	struct stat st;

	if (realpath(file, buf) == NULL) {
		snprintf(err, errlen, "realpath %s failed: %s", file,
		    strerror(errno));
		return -1;
	}
	if (realpath(pw->pw_dir, homedir) != NULL)
		comparehome = 1;

	/* check the open file to avoid races */
	if (fstat(fileno(f), &st) < 0 ||
	    (st.st_uid != 0 && st.st_uid != uid) ||
	    (st.st_mode & 022) != 0) {
		snprintf(err, errlen, "bad ownership or modes for file %s",
		    buf);
		return -1;
	}

	/* for each component of the canonical path, walking upwards */
	for (;;) {
		if ((cp = dirname(buf)) == NULL) {
			snprintf(err, errlen, "dirname() failed");
			return -1;
		}
		strlcpy(buf, cp, sizeof(buf));

		debug3("secure_filename: checking '%s'", buf);
		if (stat(buf, &st) < 0 ||
		    (st.st_uid != 0 && st.st_uid != uid) ||
		    (st.st_mode & 022) != 0) {
			snprintf(err, errlen,
			    "bad ownership or modes for directory %s", buf);
			return -1;
		}

		/* If are passed the homedir then we can stop */
		if (comparehome && strcmp(homedir, buf) == 0) {
			debug3("secure_filename: terminating check at '%s'",
			    buf);
			break;
		}
		/*
		 * dirname should always complete with a "/" path,
		 * but we can be paranoid and check for "." too
		 */
		if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0))
			break;
	}
	return 0;
}

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

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

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

	if (!auth_debug_init)
		return;

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

void
auth_debug_send(void)
{
	char *msg;

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

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

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

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

	return (&fake);
}
Commit	Line	Data
3c0ef626	1	/*
	2	* Copyright (c) 2000 Markus Friedl. All rights reserved.
	3	*
	4	* Redistribution and use in source and binary forms, with or without
	5	* modification, are permitted provided that the following conditions
	6	* are met:
	7	* 1. Redistributions of source code must retain the above copyright
	8	* notice, this list of conditions and the following disclaimer.
	9	* 2. Redistributions in binary form must reproduce the above copyright
	10	* notice, this list of conditions and the following disclaimer in the
	11	* documentation and/or other materials provided with the distribution.
	12	*
	13	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
	14	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	15	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	16	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
	17	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	18	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	19	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	20	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	21	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	22	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	23	*/
	24
	25	#include "includes.h"
dfddba3d	26	RCSID("$OpenBSD: auth.c,v 1.57 2005/01/22 08:17:59 dtucker Exp $");
3c0ef626	27
	28	#ifdef HAVE_LOGIN_H
	29	#include <login.h>
	30	#endif
540d72c3	31	#ifdef USE_SHADOW
3c0ef626	32	#include <shadow.h>
540d72c3	33	#endif
3c0ef626	34
	35	#ifdef HAVE_LIBGEN_H
	36	#include <libgen.h>
	37	#endif
	38
	39	#include "xmalloc.h"
	40	#include "match.h"
	41	#include "groupaccess.h"
	42	#include "log.h"
	43	#include "servconf.h"
	44	#include "auth.h"
	45	#include "auth-options.h"
	46	#include "canohost.h"
	47	#include "buffer.h"
	48	#include "bufaux.h"
	49	#include "uidswap.h"
b8d1a091	50	#include "misc.h"
	51	#include "bufaux.h"
	52	#include "packet.h"
dfddba3d	53	#include "loginrec.h"
dfddba3d	54	#include "monitor_wrap.h"
3c0ef626	55
	56	/* import */
	57	extern ServerOptions options;
7cac2b65	58	extern Buffer loginmsg;
3c0ef626	59
b8d1a091	60	/* Debugging messages */
	61	Buffer auth_debug;
	62	int auth_debug_init;
	63
3c0ef626	64	/*
	65	* Check if the user is allowed to log in via ssh. If user is listed
	66	* in DenyUsers or one of user's groups is listed in DenyGroups, false
	67	* will be returned. If AllowUsers isn't empty and user isn't listed
	68	* there, or if AllowGroups isn't empty and one of user's groups isn't
	69	* listed there, false will be returned.
	70	* If the user's shell is not executable, false will be returned.
	71	* Otherwise true is returned.
	72	*/
	73	int
	74	allowed_user(struct passwd * pw)
	75	{
	76	struct stat st;
7cac2b65	77	const char hostname = NULL, ipaddr = NULL, *passwd = NULL;
3c0ef626	78	char *shell;
3c0ef626	79	int i;
540d72c3	80	#ifdef USE_SHADOW
7cac2b65	81	struct spwd *spw = NULL;
bfe49944	82	#endif
3c0ef626	83
	84	/* Shouldn't be called if pw is NULL, but better safe than sorry... */
	85	if (!pw \|\| !pw->pw_name)
	86	return 0;
	87
540d72c3	88	#ifdef USE_SHADOW
7cac2b65	89	if (!options.use_pam)
	90	spw = getspnam(pw->pw_name);
	91	#ifdef HAS_SHADOW_EXPIRE
540d72c3	92	if (!options.use_pam && spw != NULL && auth_shadow_acctexpired(spw))
540d72c3	93	return 0;
7cac2b65	94	#endif /* HAS_SHADOW_EXPIRE */
540d72c3	95	#endif /* USE_SHADOW */
7cac2b65	96
540d72c3	97	/* grab passwd field for locked account check */
540d72c3	98	#ifdef USE_SHADOW
7cac2b65	99	if (spw != NULL)
	100	passwd = spw->sp_pwdp;
	101	#else
	102	passwd = pw->pw_passwd;
3c0ef626	103	#endif
3c0ef626	104
540d72c3	105	/* check for locked account */
7cac2b65	106	if (!options.use_pam && passwd && *passwd) {
	107	int locked = 0;
	108
	109	#ifdef LOCKED_PASSWD_STRING
	110	if (strcmp(passwd, LOCKED_PASSWD_STRING) == 0)
	111	locked = 1;
	112	#endif
	113	#ifdef LOCKED_PASSWD_PREFIX
	114	if (strncmp(passwd, LOCKED_PASSWD_PREFIX,
	115	strlen(LOCKED_PASSWD_PREFIX)) == 0)
	116	locked = 1;
	117	#endif
	118	#ifdef LOCKED_PASSWD_SUBSTR
	119	if (strstr(passwd, LOCKED_PASSWD_SUBSTR))
	120	locked = 1;
	121	#endif
	122	if (locked) {
	123	logit("User %.100s not allowed because account is locked",
	124	pw->pw_name);
	125	return 0;
	126	}
	127	}
	128
3c0ef626	129	/*
	130	* Get the shell from the password data. An empty shell field is
	131	* legal, and means /bin/sh.
	132	*/
	133	shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;
	134
	135	/* deny if shell does not exists or is not executable */
b8d1a091	136	if (stat(shell, &st) != 0) {
7cac2b65	137	logit("User %.100s not allowed because shell %.100s does not exist",
b8d1a091	138	pw->pw_name, shell);
3c0ef626	139	return 0;
b8d1a091	140	}
	141	if (S_ISREG(st.st_mode) == 0 \|\|
	142	(st.st_mode & (S_IXOTH\|S_IXUSR\|S_IXGRP)) == 0) {
7cac2b65	143	logit("User %.100s not allowed because shell %.100s is not executable",
b8d1a091	144	pw->pw_name, shell);
3c0ef626	145	return 0;
b8d1a091	146	}
3c0ef626	147
3c0ef626	148	if (options.num_deny_users > 0 \|\| options.num_allow_users > 0) {
7cac2b65	149	hostname = get_canonical_hostname(options.use_dns);
3c0ef626	150	ipaddr = get_remote_ipaddr();
	151	}
	152
	153	/* Return false if user is listed in DenyUsers */
	154	if (options.num_deny_users > 0) {
	155	for (i = 0; i < options.num_deny_users; i++)
	156	if (match_user(pw->pw_name, hostname, ipaddr,
b8d1a091	157	options.deny_users[i])) {
dfddba3d	158	logit("User %.100s from %.100s not allowed "
	159	"because listed in DenyUsers",
	160	pw->pw_name, hostname);
3c0ef626	161	return 0;
b8d1a091	162	}
3c0ef626	163	}
	164	/* Return false if AllowUsers isn't empty and user isn't listed there */
	165	if (options.num_allow_users > 0) {
	166	for (i = 0; i < options.num_allow_users; i++)
	167	if (match_user(pw->pw_name, hostname, ipaddr,
	168	options.allow_users[i]))
	169	break;
	170	/* i < options.num_allow_users iff we break for loop */
b8d1a091	171	if (i >= options.num_allow_users) {
dfddba3d	172	logit("User %.100s from %.100s not allowed because "
dfddba3d	173	"not listed in AllowUsers", pw->pw_name, hostname);
3c0ef626	174	return 0;
b8d1a091	175	}
3c0ef626	176	}
	177	if (options.num_deny_groups > 0 \|\| options.num_allow_groups > 0) {
	178	/* Get the user's group access list (primary and supplementary) */
b8d1a091	179	if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
dfddba3d	180	logit("User %.100s from %.100s not allowed because "
dfddba3d	181	"not in any group", pw->pw_name, hostname);
3c0ef626	182	return 0;
b8d1a091	183	}
3c0ef626	184
	185	/* Return false if one of user's groups is listed in DenyGroups */
	186	if (options.num_deny_groups > 0)
	187	if (ga_match(options.deny_groups,
	188	options.num_deny_groups)) {
	189	ga_free();
dfddba3d	190	logit("User %.100s from %.100s not allowed "
	191	"because a group is listed in DenyGroups",
	192	pw->pw_name, hostname);
3c0ef626	193	return 0;
	194	}
	195	/*
	196	* Return false if AllowGroups isn't empty and one of user's groups
	197	* isn't listed there
	198	*/
	199	if (options.num_allow_groups > 0)
	200	if (!ga_match(options.allow_groups,
	201	options.num_allow_groups)) {
	202	ga_free();
dfddba3d	203	logit("User %.100s from %.100s not allowed "
	204	"because none of user's groups are listed "
	205	"in AllowGroups", pw->pw_name, hostname);
3c0ef626	206	return 0;
	207	}
	208	ga_free();
	209	}
	210
7e82606e	211	#ifdef CUSTOM_SYS_AUTH_ALLOWED_USER
dfddba3d	212	if (!sys_auth_allowed_user(pw, &loginmsg))
7e82606e	213	return 0;
7e82606e	214	#endif
3c0ef626	215
	216	/* We found no reason not to let this user try to log on... */
	217	return 1;
	218	}
	219
3c0ef626	220	void
	221	auth_log(Authctxt authctxt, int authenticated, char method, char *info)
	222	{
	223	void (authlog) (const char fmt,...) = verbose;
	224	char *authmsg;
	225
	226	/* Raise logging level */
	227	if (authenticated == 1 \|\|
	228	!authctxt->valid \|\|
7e82606e	229	authctxt->failures >= options.max_authtries / 2 \|\|
3c0ef626	230	strcmp(method, "password") == 0)
7cac2b65	231	authlog = logit;
3c0ef626	232
	233	if (authctxt->postponed)
	234	authmsg = "Postponed";
	235	else
	236	authmsg = authenticated ? "Accepted" : "Failed";
	237
	238	authlog("%s %s for %s%.100s from %.200s port %d%s",
	239	authmsg,
	240	method,
7e82606e	241	authctxt->valid ? "" : "invalid user ",
	242	(authctxt->user && authctxt->user[0]) ?
	243	authctxt->user : "<implicit>",
3c0ef626	244	get_remote_ipaddr(),
	245	get_remote_port(),
	246	info);
d03f4262	247
7cac2b65	248	#ifdef CUSTOM_FAILED_LOGIN
dfddba3d	249	if (authenticated == 0 && !authctxt->postponed &&
	250	(strcmp(method, "password") == 0 \|\|
	251	strncmp(method, "keyboard-interactive", 20) == 0 \|\|
	252	strcmp(method, "challenge-response") == 0))
	253	record_failed_login(authctxt->user,
	254	get_canonical_hostname(options.use_dns), "ssh");
	255	#endif
	256	#ifdef SSH_AUDIT_EVENTS
	257	if (authenticated == 0 && !authctxt->postponed) {
	258	ssh_audit_event_t event;
	259
	260	debug3("audit failed auth attempt, method %s euid %d",
	261	method, (int)geteuid());
	262	/*
	263	* Because the auth loop is used in both monitor and slave,
	264	* we must be careful to send each event only once and with
	265	* enough privs to write the event.
	266	*/
	267	event = audit_classify_auth(method);
	268	switch(event) {
	269	case SSH_AUTH_FAIL_NONE:
	270	case SSH_AUTH_FAIL_PASSWD:
	271	case SSH_AUTH_FAIL_KBDINT:
	272	if (geteuid() == 0)
	273	audit_event(event);
	274	break;
	275	case SSH_AUTH_FAIL_PUBKEY:
	276	case SSH_AUTH_FAIL_HOSTBASED:
	277	case SSH_AUTH_FAIL_GSSAPI:
	278	/*
	279	* This is required to handle the case where privsep
	280	* is enabled but it's root logging in, since
	281	* use_privsep won't be cleared until after a
	282	* successful login.
	283	*/
	284	if (geteuid() == 0)
	285	audit_event(event);
	286	else
	287	PRIVSEP(audit_event(event));
	288	break;
	289	default:
	290	error("unknown authentication audit event %d", event);
	291	}
	292	}
7cac2b65	293	#endif
3c0ef626	294	}
	295
	296	/*
	297	* Check whether root logins are disallowed.
	298	*/
	299	int
	300	auth_root_allowed(char *method)
	301	{
	302	switch (options.permit_root_login) {
	303	case PERMIT_YES:
	304	return 1;
	305	break;
	306	case PERMIT_NO_PASSWD:
	307	if (strcmp(method, "password") != 0)
	308	return 1;
	309	break;
	310	case PERMIT_FORCED_ONLY:
	311	if (forced_command) {
7cac2b65	312	logit("Root login accepted for forced command.");
3c0ef626	313	return 1;
	314	}
	315	break;
	316	}
7cac2b65	317	logit("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
3c0ef626	318	return 0;
	319	}
	320
	321
	322	/*
	323	* Given a template and a passwd structure, build a filename
	324	* by substituting % tokenised options. Currently, %% becomes '%',
	325	* %h becomes the home directory and %u the username.
	326	*
	327	* This returns a buffer allocated by xmalloc.
	328	*/
	329	char *
	330	expand_filename(const char filename, struct passwd pw)
	331	{
	332	Buffer buffer;
	333	char *file;
	334	const char *cp;
	335
	336	/*
	337	* Build the filename string in the buffer by making the appropriate
	338	* substitutions to the given file name.
	339	*/
	340	buffer_init(&buffer);
	341	for (cp = filename; *cp; cp++) {
	342	if (cp[0] == '%' && cp[1] == '%') {
	343	buffer_append(&buffer, "%", 1);
	344	cp++;
	345	continue;
	346	}
	347	if (cp[0] == '%' && cp[1] == 'h') {
	348	buffer_append(&buffer, pw->pw_dir, strlen(pw->pw_dir));
	349	cp++;
	350	continue;
	351	}
	352	if (cp[0] == '%' && cp[1] == 'u') {
	353	buffer_append(&buffer, pw->pw_name,
b8d1a091	354	strlen(pw->pw_name));
3c0ef626	355	cp++;
	356	continue;
	357	}
	358	buffer_append(&buffer, cp, 1);
	359	}
	360	buffer_append(&buffer, "\0", 1);
	361
	362	/*
	363	* Ensure that filename starts anchored. If not, be backward
	364	* compatible and prepend the '%h/'
	365	*/
	366	file = xmalloc(MAXPATHLEN);
	367	cp = buffer_ptr(&buffer);
	368	if (*cp != '/')
	369	snprintf(file, MAXPATHLEN, "%s/%s", pw->pw_dir, cp);
	370	else
	371	strlcpy(file, cp, MAXPATHLEN);
	372
	373	buffer_free(&buffer);
	374	return file;
	375	}
	376
	377	char *
	378	authorized_keys_file(struct passwd *pw)
	379	{
	380	return expand_filename(options.authorized_keys_file, pw);
	381	}
	382
	383	char *
	384	authorized_keys_file2(struct passwd *pw)
	385	{
	386	return expand_filename(options.authorized_keys_file2, pw);
	387	}
	388
	389	/* return ok if key exists in sysfile or userfile */
	390	HostStatus
	391	check_key_in_hostfiles(struct passwd pw, Key key, const char *host,
	392	const char sysfile, const char userfile)
	393	{
	394	Key *found;
	395	char *user_hostfile;
	396	struct stat st;
b8d1a091	397	HostStatus host_status;
3c0ef626	398
	399	/* Check if we know the host and its host key. */
	400	found = key_new(key->type);
	401	host_status = check_host_in_hostfile(sysfile, host, key, found, NULL);
	402
	403	if (host_status != HOST_OK && userfile != NULL) {
	404	user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
	405	if (options.strict_modes &&
	406	(stat(user_hostfile, &st) == 0) &&
	407	((st.st_uid != 0 && st.st_uid != pw->pw_uid) \|\|
b8d1a091	408	(st.st_mode & 022) != 0)) {
7cac2b65	409	logit("Authentication refused for %.100s: "
3c0ef626	410	"bad owner or modes for %.200s",
	411	pw->pw_name, user_hostfile);
	412	} else {
	413	temporarily_use_uid(pw);
	414	host_status = check_host_in_hostfile(user_hostfile,
	415	host, key, found, NULL);
	416	restore_uid();
	417	}
	418	xfree(user_hostfile);
	419	}
	420	key_free(found);
	421
	422	debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ?
	423	"ok" : "not found", host);
	424	return host_status;
	425	}
	426
	427
	428	/*
	429	* Check a given file for security. This is defined as all components
d03f4262	430	* of the path to the file must be owned by either the owner of
3c0ef626	431	* of the file or root and no directories must be group or world writable.
	432	*
	433	* XXX Should any specific check be done for sym links ?
	434	*
	435	* Takes an open file descriptor, the file name, a uid and and
	436	* error buffer plus max size as arguments.
	437	*
	438	* Returns 0 on success and -1 on failure
	439	*/
	440	int
	441	secure_filename(FILE f, const char file, struct passwd *pw,
	442	char *err, size_t errlen)
	443	{
	444	uid_t uid = pw->pw_uid;
	445	char buf[MAXPATHLEN], homedir[MAXPATHLEN];
	446	char *cp;
bfe49944	447	int comparehome = 0;
3c0ef626	448	struct stat st;
	449
	450	if (realpath(file, buf) == NULL) {
	451	snprintf(err, errlen, "realpath %s failed: %s", file,
	452	strerror(errno));
	453	return -1;
	454	}
bfe49944	455	if (realpath(pw->pw_dir, homedir) != NULL)
bfe49944	456	comparehome = 1;
3c0ef626	457
	458	/* check the open file to avoid races */
	459	if (fstat(fileno(f), &st) < 0 \|\|
	460	(st.st_uid != 0 && st.st_uid != uid) \|\|
	461	(st.st_mode & 022) != 0) {
	462	snprintf(err, errlen, "bad ownership or modes for file %s",
	463	buf);
	464	return -1;
	465	}
	466
	467	/* for each component of the canonical path, walking upwards */
	468	for (;;) {
	469	if ((cp = dirname(buf)) == NULL) {
	470	snprintf(err, errlen, "dirname() failed");
	471	return -1;
	472	}
	473	strlcpy(buf, cp, sizeof(buf));
	474
	475	debug3("secure_filename: checking '%s'", buf);
	476	if (stat(buf, &st) < 0 \|\|
	477	(st.st_uid != 0 && st.st_uid != uid) \|\|
	478	(st.st_mode & 022) != 0) {
b8d1a091	479	snprintf(err, errlen,
3c0ef626	480	"bad ownership or modes for directory %s", buf);
	481	return -1;
	482	}
	483
	484	/* If are passed the homedir then we can stop */
bfe49944	485	if (comparehome && strcmp(homedir, buf) == 0) {
3c0ef626	486	debug3("secure_filename: terminating check at '%s'",
	487	buf);
	488	break;
	489	}
	490	/*
	491	* dirname should always complete with a "/" path,
	492	* but we can be paranoid and check for "." too
	493	*/
	494	if ((strcmp("/", buf) == 0) \|\| (strcmp(".", buf) == 0))
	495	break;
	496	}
	497	return 0;
	498	}
b8d1a091	499
	500	struct passwd *
	501	getpwnamallow(const char *user)
	502	{
	503	#ifdef HAVE_LOGIN_CAP
	504	extern login_cap_t *lc;
	505	#ifdef BSD_AUTH
	506	auth_session_t *as;
	507	#endif
	508	#endif
	509	struct passwd *pw;
	510
	511	pw = getpwnam(user);
d03f4262	512	if (pw == NULL) {
7e82606e	513	logit("Invalid user %.100s from %.100s",
5885a49e	514	(user && user[0]) ? user : "<implicit>",
5885a49e	515	get_remote_ipaddr());
7cac2b65	516	#ifdef CUSTOM_FAILED_LOGIN
dfddba3d	517	record_failed_login(user,
dfddba3d	518	get_canonical_hostname(options.use_dns), "ssh");
bfe49944	519	#endif
dfddba3d	520	#ifdef SSH_AUDIT_EVENTS
	521	audit_event(SSH_INVALID_USER);
	522	#endif /* SSH_AUDIT_EVENTS */
d03f4262	523	return (NULL);
	524	}
	525	if (!allowed_user(pw))
b8d1a091	526	return (NULL);
	527	#ifdef HAVE_LOGIN_CAP
	528	if ((lc = login_getclass(pw->pw_class)) == NULL) {
	529	debug("unable to get login class: %s", user);
	530	return (NULL);
	531	}
	532	#ifdef BSD_AUTH
	533	if ((as = auth_open()) == NULL \|\| auth_setpwd(as, pw) != 0 \|\|
	534	auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
	535	debug("Approval failure for %s", user);
	536	pw = NULL;
	537	}
	538	if (as != NULL)
	539	auth_close(as);
	540	#endif
	541	#endif
	542	if (pw != NULL)
	543	return (pwcopy(pw));
	544	return (NULL);
	545	}
	546
	547	void
	548	auth_debug_add(const char *fmt,...)
	549	{
	550	char buf[1024];
	551	va_list args;
	552
	553	if (!auth_debug_init)
	554	return;
	555
	556	va_start(args, fmt);
	557	vsnprintf(buf, sizeof(buf), fmt, args);
	558	va_end(args);
	559	buffer_put_cstring(&auth_debug, buf);
	560	}
	561
	562	void
	563	auth_debug_send(void)
	564	{
	565	char *msg;
	566
	567	if (!auth_debug_init)
	568	return;
	569	while (buffer_len(&auth_debug)) {
	570	msg = buffer_get_string(&auth_debug, NULL);
	571	packet_send_debug("%s", msg);
	572	xfree(msg);
	573	}
	574	}
	575
	576	void
	577	auth_debug_reset(void)
	578	{
	579	if (auth_debug_init)
	580	buffer_clear(&auth_debug);
	581	else {
	582	buffer_init(&auth_debug);
	583	auth_debug_init = 1;
	584	}
	585	}
7cac2b65	586
	587	struct passwd *
	588	fakepw(void)
	589	{
	590	static struct passwd fake;
	591
	592	memset(&fake, 0, sizeof(fake));
	593	fake.pw_name = "NOUSER";
	594	fake.pw_passwd =
540d72c3	595	"$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK";
7cac2b65	596	fake.pw_gecos = "NOUSER";
7e82606e	597	fake.pw_uid = (uid_t)-1;
7e82606e	598	fake.pw_gid = (gid_t)-1;
7cac2b65	599	#ifdef HAVE_PW_CLASS_IN_PASSWD
	600	fake.pw_class = "";
	601	#endif
	602	fake.pw_dir = "/nonexist";
	603	fake.pw_shell = "/nonexist";
	604
	605	return (&fake);
	606	}