[gssapi-openssh.git] / openssh / auth.c

/* $OpenBSD: auth.c,v 1.80 2008/11/04 07:58:09 djm Exp $ */
/*
 * 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"

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/param.h>

#include <netinet/in.h>

#include <errno.h>
#include <fcntl.h>
#ifdef HAVE_PATHS_H
# include <paths.h>
#endif
#include <pwd.h>
#ifdef HAVE_LOGIN_H
#include <login.h>
#endif
#ifdef USE_SHADOW
#include <shadow.h>
#endif
#ifdef HAVE_LIBGEN_H
#include <libgen.h>
#endif
#include <stdarg.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>

#include "xmalloc.h"
#include "match.h"
#include "groupaccess.h"
#include "log.h"
#include "buffer.h"
#include "servconf.h"
#include "key.h"
#include "hostfile.h"
#include "auth.h"
#include "auth-options.h"
#include "canohost.h"
#include "uidswap.h"
#include "misc.h"
#include "packet.h"
#include "loginrec.h"
#ifdef GSSAPI
#include "ssh-gss.h"
#endif
#include "monitor_wrap.h"

#include "version.h"
#include "ssh-globus-usage.h"

/* import */
extern ServerOptions options;
extern int use_privsep;
extern Buffer loginmsg;
extern struct passwd *privsep_pw;

/* 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;
	u_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 */
	passwd = pw->pw_passwd;
#ifdef USE_SHADOW
	if (spw != NULL)
#ifdef USE_LIBIAF
		passwd = get_iaf_password(pw);
#else
		passwd = spw->sp_pwdp;
#endif /* USE_LIBIAF */
#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
#ifdef USE_LIBIAF
		free(passwd);
#endif /* USE_LIBIAF */
		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 ||
	    options.num_deny_groups > 0 || options.num_allow_groups > 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;

	if (use_privsep && !mm_is_monitor() && !authctxt->postponed)
		return;

	/* 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 : "unknown",
	    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");
# ifdef WITH_AIXAUTHENTICATE
	if (authenticated)
		sys_auth_record_login(authctxt->user,
		    get_canonical_hostname(options.use_dns), "ssh", &loginmsg);
# endif
#endif
#ifdef SSH_AUDIT_EVENTS
	if (authenticated == 0 && !authctxt->postponed)
		audit_event(audit_classify_auth(method));
#endif
	if (authenticated) {
		char *userdn = NULL;
		char *mech_name = NULL;
		ssh_gssapi_get_client_info(&userdn, &mech_name);
		debug("REPORTING (%s) (%s) (%s) (%s) (%s) (%s) (%s)",
			 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION),
			 method, mech_name?mech_name:"NULL", get_remote_ipaddr(),
			 (authctxt->user && authctxt->user[0])?
				authctxt->user : "unknown",
			userdn?userdn:"NULL");
		ssh_globus_send_usage_metrics(SSH_RELEASE,
					SSLeay_version(SSLEAY_VERSION),
					method, mech_name, get_remote_ipaddr(),
					authctxt->user, userdn);
	}
}

/*
 * Check whether root logins are disallowed.
 */
int
auth_root_allowed(char *method)
{
	switch (options.permit_root_login) {
	case PERMIT_YES:
		return 1;
	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_authorized_keys(const char *filename, struct passwd *pw)
{
	char *file, ret[MAXPATHLEN];
	int i;

	file = percent_expand(filename, "h", pw->pw_dir,
	    "u", pw->pw_name, (char *)NULL);

	/*
	 * Ensure that filename starts anchored. If not, be backward
	 * compatible and prepend the '%h/'
	 */
	if (*file == '/')
		return (file);

	i = snprintf(ret, sizeof(ret), "%s/%s", pw->pw_dir, file);
	if (i < 0 || (size_t)i >= sizeof(ret))
		fatal("expand_authorized_keys: path too long");
	xfree(file);
	return (xstrdup(ret));
}

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

char *
authorized_keys_file2(struct passwd *pw)
{
	return expand_authorized_keys(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
 */
static 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;
}

FILE *
auth_openkeyfile(const char *file, struct passwd *pw, int strict_modes)
{
	char line[1024];
	struct stat st;
	int fd;
	FILE *f;

	/*
	 * Open the file containing the authorized keys
	 * Fail quietly if file does not exist
	 */
	if ((fd = open(file, O_RDONLY|O_NONBLOCK)) == -1)
		return NULL;

	if (fstat(fd, &st) < 0) {
		close(fd);
		return NULL;
	}
	if (!S_ISREG(st.st_mode)) {
		logit("User %s authorized keys %s is not a regular file",
		    pw->pw_name, file);
		close(fd);
		return NULL;
	}
	unset_nonblock(fd);
	if ((f = fdopen(fd, "r")) == NULL) {
		close(fd);
		return NULL;
	}
	if (options.strict_modes &&
	    secure_filename(f, file, pw, line, sizeof(line)) != 0) {
		fclose(f);
		logit("Authentication refused: %s", line);
		return NULL;
	}

	return f;
}

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;

	parse_server_match_config(&options, user,
	    get_canonical_hostname(options.use_dns), get_remote_ipaddr());

	pw = getpwnam(user);
#ifdef USE_PAM
	if (options.use_pam && options.permit_pam_user_change && pw == NULL)
		pw = sshpam_getpw(user);
#endif
	if (pw == NULL) {
		logit("Invalid user %.100s from %.100s",
		      (user && user[0]) ? user : "unknown",
		      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 = privsep_pw == NULL ? (uid_t)-1 : privsep_pw->pw_uid;
	fake.pw_gid = privsep_pw == NULL ? (gid_t)-1 : privsep_pw->pw_gid;
#ifdef HAVE_PW_CLASS_IN_PASSWD
	fake.pw_class = "";
#endif
	fake.pw_dir = "/nonexist";
	fake.pw_shell = "/nonexist";

	return (&fake);
}
Commit	Line	Data
5262cbfb	1	/* $OpenBSD: auth.c,v 1.80 2008/11/04 07:58:09 djm Exp $ */
3c0ef626	2	/*
	3	* Copyright (c) 2000 Markus Friedl. All rights reserved.
	4	*
	5	* Redistribution and use in source and binary forms, with or without
	6	* modification, are permitted provided that the following conditions
	7	* are met:
	8	* 1. Redistributions of source code must retain the above copyright
	9	* notice, this list of conditions and the following disclaimer.
	10	* 2. Redistributions in binary form must reproduce the above copyright
	11	* notice, this list of conditions and the following disclaimer in the
	12	* documentation and/or other materials provided with the distribution.
	13	*
	14	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
	15	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	16	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	17	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
	18	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	19	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	20	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	21	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	22	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	23	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	24	*/
	25
	26	#include "includes.h"
3c0ef626	27
30460aeb	28	#include <sys/types.h>
	29	#include <sys/stat.h>
	30	#include <sys/param.h>
	31
	32	#include <netinet/in.h>
	33
	34	#include <errno.h>
5156b1a1	35	#include <fcntl.h>
30460aeb	36	#ifdef HAVE_PATHS_H
	37	# include <paths.h>
	38	#endif
	39	#include <pwd.h>
3c0ef626	40	#ifdef HAVE_LOGIN_H
	41	#include <login.h>
	42	#endif
540d72c3	43	#ifdef USE_SHADOW
3c0ef626	44	#include <shadow.h>
540d72c3	45	#endif
3c0ef626	46	#ifdef HAVE_LIBGEN_H
	47	#include <libgen.h>
	48	#endif
30460aeb	49	#include <stdarg.h>
	50	#include <stdio.h>
	51	#include <string.h>
5156b1a1	52	#include <unistd.h>
3c0ef626	53
	54	#include "xmalloc.h"
	55	#include "match.h"
	56	#include "groupaccess.h"
	57	#include "log.h"
30460aeb	58	#include "buffer.h"
3c0ef626	59	#include "servconf.h"
30460aeb	60	#include "key.h"
30460aeb	61	#include "hostfile.h"
3c0ef626	62	#include "auth.h"
	63	#include "auth-options.h"
	64	#include "canohost.h"
3c0ef626	65	#include "uidswap.h"
b8d1a091	66	#include "misc.h"
b8d1a091	67	#include "packet.h"
dfddba3d	68	#include "loginrec.h"
30460aeb	69	#ifdef GSSAPI
	70	#include "ssh-gss.h"
	71	#endif
dfddba3d	72	#include "monitor_wrap.h"
3c0ef626	73
9f2c8cb9	74	#include "version.h"
	75	#include "ssh-globus-usage.h"
	76
3c0ef626	77	/* import */
3c0ef626	78	extern ServerOptions options;
30460aeb	79	extern int use_privsep;
7cac2b65	80	extern Buffer loginmsg;
30460aeb	81	extern struct passwd *privsep_pw;
3c0ef626	82
b8d1a091	83	/* Debugging messages */
	84	Buffer auth_debug;
	85	int auth_debug_init;
	86
3c0ef626	87	/*
	88	* Check if the user is allowed to log in via ssh. If user is listed
	89	* in DenyUsers or one of user's groups is listed in DenyGroups, false
	90	* will be returned. If AllowUsers isn't empty and user isn't listed
	91	* there, or if AllowGroups isn't empty and one of user's groups isn't
	92	* listed there, false will be returned.
	93	* If the user's shell is not executable, false will be returned.
	94	* Otherwise true is returned.
	95	*/
	96	int
	97	allowed_user(struct passwd * pw)
	98	{
	99	struct stat st;
7cac2b65	100	const char hostname = NULL, ipaddr = NULL, *passwd = NULL;
3c0ef626	101	char *shell;
2ce0bfe4	102	u_int i;
540d72c3	103	#ifdef USE_SHADOW
7cac2b65	104	struct spwd *spw = NULL;
bfe49944	105	#endif
3c0ef626	106
	107	/* Shouldn't be called if pw is NULL, but better safe than sorry... */
	108	if (!pw \|\| !pw->pw_name)
	109	return 0;
	110
540d72c3	111	#ifdef USE_SHADOW
7cac2b65	112	if (!options.use_pam)
	113	spw = getspnam(pw->pw_name);
	114	#ifdef HAS_SHADOW_EXPIRE
540d72c3	115	if (!options.use_pam && spw != NULL && auth_shadow_acctexpired(spw))
540d72c3	116	return 0;
7cac2b65	117	#endif /* HAS_SHADOW_EXPIRE */
540d72c3	118	#endif /* USE_SHADOW */
7cac2b65	119
540d72c3	120	/* grab passwd field for locked account check */
5156b1a1	121	passwd = pw->pw_passwd;
540d72c3	122	#ifdef USE_SHADOW
7cac2b65	123	if (spw != NULL)
fa0f0f45	124	#ifdef USE_LIBIAF
2ce0bfe4	125	passwd = get_iaf_password(pw);
2ce0bfe4	126	#else
7cac2b65	127	passwd = spw->sp_pwdp;
fa0f0f45	128	#endif /* USE_LIBIAF */
3c0ef626	129	#endif
3c0ef626	130
540d72c3	131	/* check for locked account */
7cac2b65	132	if (!options.use_pam && passwd && *passwd) {
	133	int locked = 0;
	134
	135	#ifdef LOCKED_PASSWD_STRING
	136	if (strcmp(passwd, LOCKED_PASSWD_STRING) == 0)
	137	locked = 1;
	138	#endif
	139	#ifdef LOCKED_PASSWD_PREFIX
	140	if (strncmp(passwd, LOCKED_PASSWD_PREFIX,
	141	strlen(LOCKED_PASSWD_PREFIX)) == 0)
	142	locked = 1;
	143	#endif
	144	#ifdef LOCKED_PASSWD_SUBSTR
	145	if (strstr(passwd, LOCKED_PASSWD_SUBSTR))
	146	locked = 1;
	147	#endif
fa0f0f45	148	#ifdef USE_LIBIAF
2ce0bfe4	149	free(passwd);
fa0f0f45	150	#endif /* USE_LIBIAF */
7cac2b65	151	if (locked) {
	152	logit("User %.100s not allowed because account is locked",
	153	pw->pw_name);
	154	return 0;
	155	}
	156	}
	157
3c0ef626	158	/*
	159	* Get the shell from the password data. An empty shell field is
	160	* legal, and means /bin/sh.
	161	*/
	162	shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;
	163
	164	/* deny if shell does not exists or is not executable */
b8d1a091	165	if (stat(shell, &st) != 0) {
7cac2b65	166	logit("User %.100s not allowed because shell %.100s does not exist",
b8d1a091	167	pw->pw_name, shell);
3c0ef626	168	return 0;
b8d1a091	169	}
	170	if (S_ISREG(st.st_mode) == 0 \|\|
	171	(st.st_mode & (S_IXOTH\|S_IXUSR\|S_IXGRP)) == 0) {
7cac2b65	172	logit("User %.100s not allowed because shell %.100s is not executable",
b8d1a091	173	pw->pw_name, shell);
3c0ef626	174	return 0;
b8d1a091	175	}
3c0ef626	176
8b32eddc	177	if (options.num_deny_users > 0 \|\| options.num_allow_users > 0 \|\|
8b32eddc	178	options.num_deny_groups > 0 \|\| options.num_allow_groups > 0) {
7cac2b65	179	hostname = get_canonical_hostname(options.use_dns);
3c0ef626	180	ipaddr = get_remote_ipaddr();
	181	}
	182
	183	/* Return false if user is listed in DenyUsers */
	184	if (options.num_deny_users > 0) {
	185	for (i = 0; i < options.num_deny_users; i++)
	186	if (match_user(pw->pw_name, hostname, ipaddr,
b8d1a091	187	options.deny_users[i])) {
dfddba3d	188	logit("User %.100s from %.100s not allowed "
	189	"because listed in DenyUsers",
	190	pw->pw_name, hostname);
3c0ef626	191	return 0;
b8d1a091	192	}
3c0ef626	193	}
	194	/* Return false if AllowUsers isn't empty and user isn't listed there */
	195	if (options.num_allow_users > 0) {
	196	for (i = 0; i < options.num_allow_users; i++)
	197	if (match_user(pw->pw_name, hostname, ipaddr,
	198	options.allow_users[i]))
	199	break;
	200	/* i < options.num_allow_users iff we break for loop */
b8d1a091	201	if (i >= options.num_allow_users) {
dfddba3d	202	logit("User %.100s from %.100s not allowed because "
dfddba3d	203	"not listed in AllowUsers", pw->pw_name, hostname);
3c0ef626	204	return 0;
b8d1a091	205	}
3c0ef626	206	}
	207	if (options.num_deny_groups > 0 \|\| options.num_allow_groups > 0) {
	208	/* Get the user's group access list (primary and supplementary) */
b8d1a091	209	if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
dfddba3d	210	logit("User %.100s from %.100s not allowed because "
dfddba3d	211	"not in any group", pw->pw_name, hostname);
3c0ef626	212	return 0;
b8d1a091	213	}
3c0ef626	214
	215	/* Return false if one of user's groups is listed in DenyGroups */
	216	if (options.num_deny_groups > 0)
	217	if (ga_match(options.deny_groups,
	218	options.num_deny_groups)) {
	219	ga_free();
dfddba3d	220	logit("User %.100s from %.100s not allowed "
	221	"because a group is listed in DenyGroups",
	222	pw->pw_name, hostname);
3c0ef626	223	return 0;
	224	}
	225	/*
	226	* Return false if AllowGroups isn't empty and one of user's groups
	227	* isn't listed there
	228	*/
	229	if (options.num_allow_groups > 0)
	230	if (!ga_match(options.allow_groups,
	231	options.num_allow_groups)) {
	232	ga_free();
dfddba3d	233	logit("User %.100s from %.100s not allowed "
	234	"because none of user's groups are listed "
	235	"in AllowGroups", pw->pw_name, hostname);
3c0ef626	236	return 0;
	237	}
	238	ga_free();
	239	}
	240
7e82606e	241	#ifdef CUSTOM_SYS_AUTH_ALLOWED_USER
dfddba3d	242	if (!sys_auth_allowed_user(pw, &loginmsg))
7e82606e	243	return 0;
7e82606e	244	#endif
3c0ef626	245
	246	/* We found no reason not to let this user try to log on... */
	247	return 1;
	248	}
	249
3c0ef626	250	void
	251	auth_log(Authctxt authctxt, int authenticated, char method, char *info)
	252	{
	253	void (authlog) (const char fmt,...) = verbose;
	254	char *authmsg;
	255
30460aeb	256	if (use_privsep && !mm_is_monitor() && !authctxt->postponed)
	257	return;
	258
3c0ef626	259	/* Raise logging level */
	260	if (authenticated == 1 \|\|
	261	!authctxt->valid \|\|
7e82606e	262	authctxt->failures >= options.max_authtries / 2 \|\|
3c0ef626	263	strcmp(method, "password") == 0)
7cac2b65	264	authlog = logit;
3c0ef626	265
	266	if (authctxt->postponed)
	267	authmsg = "Postponed";
	268	else
	269	authmsg = authenticated ? "Accepted" : "Failed";
	270
	271	authlog("%s %s for %s%.100s from %.200s port %d%s",
	272	authmsg,
	273	method,
7e82606e	274	authctxt->valid ? "" : "invalid user ",
7e82606e	275	(authctxt->user && authctxt->user[0]) ?
86a22a0a	276	authctxt->user : "unknown",
3c0ef626	277	get_remote_ipaddr(),
	278	get_remote_port(),
	279	info);
d03f4262	280
7cac2b65	281	#ifdef CUSTOM_FAILED_LOGIN
dfddba3d	282	if (authenticated == 0 && !authctxt->postponed &&
	283	(strcmp(method, "password") == 0 \|\|
	284	strncmp(method, "keyboard-interactive", 20) == 0 \|\|
	285	strcmp(method, "challenge-response") == 0))
	286	record_failed_login(authctxt->user,
	287	get_canonical_hostname(options.use_dns), "ssh");
30460aeb	288	# ifdef WITH_AIXAUTHENTICATE
	289	if (authenticated)
	290	sys_auth_record_login(authctxt->user,
	291	get_canonical_hostname(options.use_dns), "ssh", &loginmsg);
	292	# endif
dfddba3d	293	#endif
dfddba3d	294	#ifdef SSH_AUDIT_EVENTS
30460aeb	295	if (authenticated == 0 && !authctxt->postponed)
30460aeb	296	audit_event(audit_classify_auth(method));
7cac2b65	297	#endif
9f2c8cb9	298	if (authenticated) {
	299	char *userdn = NULL;
	300	char *mech_name = NULL;
	301	ssh_gssapi_get_client_info(&userdn, &mech_name);
	302	debug("REPORTING (%s) (%s) (%s) (%s) (%s) (%s) (%s)",
	303	SSH_RELEASE, SSLeay_version(SSLEAY_VERSION),
	304	method, mech_name?mech_name:"NULL", get_remote_ipaddr(),
	305	(authctxt->user && authctxt->user[0])?
	306	authctxt->user : "unknown",
	307	userdn?userdn:"NULL");
	308	ssh_globus_send_usage_metrics(SSH_RELEASE,
	309	SSLeay_version(SSLEAY_VERSION),
	310	method, mech_name, get_remote_ipaddr(),
	311	authctxt->user, userdn);
	312	}
3c0ef626	313	}
	314
	315	/*
	316	* Check whether root logins are disallowed.
	317	*/
	318	int
	319	auth_root_allowed(char *method)
	320	{
	321	switch (options.permit_root_login) {
	322	case PERMIT_YES:
	323	return 1;
3c0ef626	324	case PERMIT_NO_PASSWD:
	325	if (strcmp(method, "password") != 0)
	326	return 1;
	327	break;
	328	case PERMIT_FORCED_ONLY:
	329	if (forced_command) {
7cac2b65	330	logit("Root login accepted for forced command.");
3c0ef626	331	return 1;
	332	}
	333	break;
	334	}
7cac2b65	335	logit("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
3c0ef626	336	return 0;
	337	}
	338
	339
	340	/*
	341	* Given a template and a passwd structure, build a filename
	342	* by substituting % tokenised options. Currently, %% becomes '%',
	343	* %h becomes the home directory and %u the username.
	344	*
	345	* This returns a buffer allocated by xmalloc.
	346	*/
ae82558b	347	char *
2ce0bfe4	348	expand_authorized_keys(const char filename, struct passwd pw)
3c0ef626	349	{
30460aeb	350	char *file, ret[MAXPATHLEN];
30460aeb	351	int i;
3c0ef626	352
2ce0bfe4	353	file = percent_expand(filename, "h", pw->pw_dir,
2ce0bfe4	354	"u", pw->pw_name, (char *)NULL);
3c0ef626	355
	356	/*
	357	* Ensure that filename starts anchored. If not, be backward
	358	* compatible and prepend the '%h/'
	359	*/
2ce0bfe4	360	if (*file == '/')
	361	return (file);
	362
30460aeb	363	i = snprintf(ret, sizeof(ret), "%s/%s", pw->pw_dir, file);
30460aeb	364	if (i < 0 \|\| (size_t)i >= sizeof(ret))
2ce0bfe4	365	fatal("expand_authorized_keys: path too long");
2ce0bfe4	366	xfree(file);
30460aeb	367	return (xstrdup(ret));
3c0ef626	368	}
	369
	370	char *
	371	authorized_keys_file(struct passwd *pw)
	372	{
2ce0bfe4	373	return expand_authorized_keys(options.authorized_keys_file, pw);
3c0ef626	374	}
	375
	376	char *
	377	authorized_keys_file2(struct passwd *pw)
	378	{
2ce0bfe4	379	return expand_authorized_keys(options.authorized_keys_file2, pw);
3c0ef626	380	}
	381
	382	/* return ok if key exists in sysfile or userfile */
	383	HostStatus
	384	check_key_in_hostfiles(struct passwd pw, Key key, const char *host,
	385	const char sysfile, const char userfile)
	386	{
	387	Key *found;
	388	char *user_hostfile;
	389	struct stat st;
b8d1a091	390	HostStatus host_status;
3c0ef626	391
	392	/* Check if we know the host and its host key. */
	393	found = key_new(key->type);
	394	host_status = check_host_in_hostfile(sysfile, host, key, found, NULL);
	395
	396	if (host_status != HOST_OK && userfile != NULL) {
	397	user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
	398	if (options.strict_modes &&
	399	(stat(user_hostfile, &st) == 0) &&
	400	((st.st_uid != 0 && st.st_uid != pw->pw_uid) \|\|
b8d1a091	401	(st.st_mode & 022) != 0)) {
7cac2b65	402	logit("Authentication refused for %.100s: "
3c0ef626	403	"bad owner or modes for %.200s",
	404	pw->pw_name, user_hostfile);
	405	} else {
	406	temporarily_use_uid(pw);
	407	host_status = check_host_in_hostfile(user_hostfile,
	408	host, key, found, NULL);
	409	restore_uid();
	410	}
	411	xfree(user_hostfile);
	412	}
	413	key_free(found);
	414
	415	debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ?
	416	"ok" : "not found", host);
	417	return host_status;
	418	}
	419
	420
	421	/*
	422	* Check a given file for security. This is defined as all components
d03f4262	423	* of the path to the file must be owned by either the owner of
3c0ef626	424	* of the file or root and no directories must be group or world writable.
	425	*
	426	* XXX Should any specific check be done for sym links ?
	427	*
	428	* Takes an open file descriptor, the file name, a uid and and
	429	* error buffer plus max size as arguments.
	430	*
	431	* Returns 0 on success and -1 on failure
	432	*/
5156b1a1	433	static int
3c0ef626	434	secure_filename(FILE f, const char file, struct passwd *pw,
	435	char *err, size_t errlen)
	436	{
	437	uid_t uid = pw->pw_uid;
	438	char buf[MAXPATHLEN], homedir[MAXPATHLEN];
	439	char *cp;
bfe49944	440	int comparehome = 0;
3c0ef626	441	struct stat st;
	442
	443	if (realpath(file, buf) == NULL) {
	444	snprintf(err, errlen, "realpath %s failed: %s", file,
	445	strerror(errno));
	446	return -1;
	447	}
bfe49944	448	if (realpath(pw->pw_dir, homedir) != NULL)
bfe49944	449	comparehome = 1;
3c0ef626	450
	451	/* check the open file to avoid races */
	452	if (fstat(fileno(f), &st) < 0 \|\|
	453	(st.st_uid != 0 && st.st_uid != uid) \|\|
	454	(st.st_mode & 022) != 0) {
	455	snprintf(err, errlen, "bad ownership or modes for file %s",
	456	buf);
	457	return -1;
	458	}
	459
	460	/* for each component of the canonical path, walking upwards */
	461	for (;;) {
	462	if ((cp = dirname(buf)) == NULL) {
	463	snprintf(err, errlen, "dirname() failed");
	464	return -1;
	465	}
	466	strlcpy(buf, cp, sizeof(buf));
	467
	468	debug3("secure_filename: checking '%s'", buf);
	469	if (stat(buf, &st) < 0 \|\|
	470	(st.st_uid != 0 && st.st_uid != uid) \|\|
	471	(st.st_mode & 022) != 0) {
b8d1a091	472	snprintf(err, errlen,
3c0ef626	473	"bad ownership or modes for directory %s", buf);
	474	return -1;
	475	}
	476
	477	/* If are passed the homedir then we can stop */
bfe49944	478	if (comparehome && strcmp(homedir, buf) == 0) {
3c0ef626	479	debug3("secure_filename: terminating check at '%s'",
	480	buf);
	481	break;
	482	}
	483	/*
	484	* dirname should always complete with a "/" path,
	485	* but we can be paranoid and check for "." too
	486	*/
	487	if ((strcmp("/", buf) == 0) \|\| (strcmp(".", buf) == 0))
	488	break;
	489	}
	490	return 0;
	491	}
b8d1a091	492
5156b1a1	493	FILE *
	494	auth_openkeyfile(const char file, struct passwd pw, int strict_modes)
	495	{
	496	char line[1024];
	497	struct stat st;
	498	int fd;
	499	FILE *f;
	500
	501	/*
	502	* Open the file containing the authorized keys
	503	* Fail quietly if file does not exist
	504	*/
	505	if ((fd = open(file, O_RDONLY\|O_NONBLOCK)) == -1)
	506	return NULL;
	507
	508	if (fstat(fd, &st) < 0) {
	509	close(fd);
	510	return NULL;
	511	}
	512	if (!S_ISREG(st.st_mode)) {
	513	logit("User %s authorized keys %s is not a regular file",
	514	pw->pw_name, file);
	515	close(fd);
	516	return NULL;
	517	}
	518	unset_nonblock(fd);
	519	if ((f = fdopen(fd, "r")) == NULL) {
	520	close(fd);
	521	return NULL;
	522	}
	523	if (options.strict_modes &&
	524	secure_filename(f, file, pw, line, sizeof(line)) != 0) {
	525	fclose(f);
	526	logit("Authentication refused: %s", line);
	527	return NULL;
	528	}
	529
	530	return f;
	531	}
	532
b8d1a091	533	struct passwd *
	534	getpwnamallow(const char *user)
	535	{
	536	#ifdef HAVE_LOGIN_CAP
	537	extern login_cap_t *lc;
	538	#ifdef BSD_AUTH
	539	auth_session_t *as;
	540	#endif
	541	#endif
	542	struct passwd *pw;
	543
30460aeb	544	parse_server_match_config(&options, user,
	545	get_canonical_hostname(options.use_dns), get_remote_ipaddr());
	546
b8d1a091	547	pw = getpwnam(user);
d037a8b0	548	#ifdef USE_PAM
	549	if (options.use_pam && options.permit_pam_user_change && pw == NULL)
	550	pw = sshpam_getpw(user);
	551	#endif
d03f4262	552	if (pw == NULL) {
7e82606e	553	logit("Invalid user %.100s from %.100s",
86a22a0a	554	(user && user[0]) ? user : "unknown",
5885a49e	555	get_remote_ipaddr());
7cac2b65	556	#ifdef CUSTOM_FAILED_LOGIN
dfddba3d	557	record_failed_login(user,
dfddba3d	558	get_canonical_hostname(options.use_dns), "ssh");
bfe49944	559	#endif
dfddba3d	560	#ifdef SSH_AUDIT_EVENTS
	561	audit_event(SSH_INVALID_USER);
	562	#endif /* SSH_AUDIT_EVENTS */
d03f4262	563	return (NULL);
	564	}
	565	if (!allowed_user(pw))
b8d1a091	566	return (NULL);
	567	#ifdef HAVE_LOGIN_CAP
	568	if ((lc = login_getclass(pw->pw_class)) == NULL) {
	569	debug("unable to get login class: %s", user);
	570	return (NULL);
	571	}
	572	#ifdef BSD_AUTH
	573	if ((as = auth_open()) == NULL \|\| auth_setpwd(as, pw) != 0 \|\|
	574	auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
	575	debug("Approval failure for %s", user);
	576	pw = NULL;
	577	}
	578	if (as != NULL)
	579	auth_close(as);
	580	#endif
	581	#endif
	582	if (pw != NULL)
	583	return (pwcopy(pw));
	584	return (NULL);
	585	}
	586
	587	void
	588	auth_debug_add(const char *fmt,...)
	589	{
	590	char buf[1024];
	591	va_list args;
	592
	593	if (!auth_debug_init)
	594	return;
	595
	596	va_start(args, fmt);
	597	vsnprintf(buf, sizeof(buf), fmt, args);
	598	va_end(args);
	599	buffer_put_cstring(&auth_debug, buf);
	600	}
	601
	602	void
	603	auth_debug_send(void)
	604	{
	605	char *msg;
	606
	607	if (!auth_debug_init)
	608	return;
	609	while (buffer_len(&auth_debug)) {
	610	msg = buffer_get_string(&auth_debug, NULL);
	611	packet_send_debug("%s", msg);
	612	xfree(msg);
	613	}
	614	}
	615
	616	void
	617	auth_debug_reset(void)
	618	{
	619	if (auth_debug_init)
	620	buffer_clear(&auth_debug);
	621	else {
	622	buffer_init(&auth_debug);
	623	auth_debug_init = 1;
	624	}
	625	}
7cac2b65	626
	627	struct passwd *
	628	fakepw(void)
	629	{
	630	static struct passwd fake;
	631
	632	memset(&fake, 0, sizeof(fake));
	633	fake.pw_name = "NOUSER";
	634	fake.pw_passwd =
540d72c3	635	"$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK";
7cac2b65	636	fake.pw_gecos = "NOUSER";
0b90ac93	637	fake.pw_uid = privsep_pw == NULL ? (uid_t)-1 : privsep_pw->pw_uid;
0b90ac93	638	fake.pw_gid = privsep_pw == NULL ? (gid_t)-1 : privsep_pw->pw_gid;
7cac2b65	639	#ifdef HAVE_PW_CLASS_IN_PASSWD
	640	fake.pw_class = "";
	641	#endif
	642	fake.pw_dir = "/nonexist";
	643	fake.pw_shell = "/nonexist";
	644
	645	return (&fake);
	646	}