/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 *
 * Copyright 2023 OmniOS Community Edition (OmniOSce) Association.
 */

#include <kadm5/admin.h>
#include <krb5.h>

#include <security/pam_appl.h>
#include <security/pam_modules.h>
#include <security/pam_impl.h>
#include <syslog.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <pwd.h>
#include <libintl.h>
#include <netdb.h>
#include "utils.h"
#include <shadow.h>

#include "krb5_repository.h"

#define	KRB5_AUTOMIGRATE_DATA	"SUNW-KRB5-AUTOMIGRATE-DATA"

#define	min(a, b) ((a) < (b) ? (a) : (b))

/*
 * pam_sm_acct_mgmt	  main account managment routine.
 */

static int
fetch_princ_entry(
	krb5_module_data_t *kmd,
	const char *princ_str,
	kadm5_principal_ent_rec *prent,	/* out */
	int debug)

{
	kadm5_ret_t		code;
	krb5_principal 		princ = 0;
	char 			admin_realm[1024];
	char			kprinc[2*MAXHOSTNAMELEN];
	char			*cpw_service, *password;
	void 			*server_handle;
	krb5_context		context;
	kadm5_config_params	params;

	password = kmd->password;
	context = kmd->kcontext;

	if ((code = get_kmd_kuser(context, princ_str,
	    kprinc, 2 * MAXHOSTNAMELEN)) != 0) {
		return (code);
	}

	code = krb5_parse_name(context, kprinc, &princ);
	if (code != 0) {
		return (PAM_SYSTEM_ERR);
	}

	if (strlen(password) == 0) {
		krb5_free_principal(context, princ);
		if (debug)
			__pam_log(LOG_AUTH | LOG_DEBUG,
			    "PAM-KRB5 (acct): fetch_princ_entry: pwlen=0");
		return (PAM_AUTH_ERR);
	}

	(void) strlcpy(admin_realm,
		    krb5_princ_realm(context, princ)->data,
		    sizeof (admin_realm));

	(void) memset((char *)&params, 0, sizeof (params));
	params.mask |= KADM5_CONFIG_REALM;
	params.realm = admin_realm;

	if (kadm5_get_cpw_host_srv_name(context, admin_realm, &cpw_service)) {
		__pam_log(LOG_AUTH | LOG_ERR,
			"PAM-KRB5 (acct):  unable to get host based "
			"service name for realm '%s'",
			admin_realm);
		krb5_free_principal(context, princ);
		return (PAM_SYSTEM_ERR);
	}

	code = kadm5_init_with_password(kprinc, password, cpw_service,
					&params, KADM5_STRUCT_VERSION,
					KADM5_API_VERSION_2, NULL,
					&server_handle);
	if (code != 0) {
		if (debug)
			__pam_log(LOG_AUTH | LOG_DEBUG,
			    "PAM-KRB5 (acct): fetch_princ_entry: "
			    "init_with_pw failed: code = %d", code);
		krb5_free_principal(context, princ);
		return ((code == KADM5_BAD_PASSWORD) ?
			PAM_AUTH_ERR : PAM_SYSTEM_ERR);
	}

	if (_kadm5_get_kpasswd_protocol(server_handle) != KRB5_CHGPWD_RPCSEC) {
		if (debug)
			__pam_log(LOG_AUTH | LOG_DEBUG,
			    "PAM-KRB5 (acct): fetch_princ_entry: "
			    "non-RPCSEC_GSS chpw server, can't get "
			    "princ entry");
		(void) kadm5_destroy(server_handle);
		krb5_free_principal(context, princ);
		return (PAM_SYSTEM_ERR);
	}

	code = kadm5_get_principal(server_handle, princ, prent,
				KADM5_PRINCIPAL_NORMAL_MASK);

	if (code != 0) {
		(void) kadm5_destroy(server_handle);
		krb5_free_principal(context, princ);
		return ((code == KADM5_UNK_PRINC) ?
			PAM_USER_UNKNOWN : PAM_SYSTEM_ERR);
	}

	(void) kadm5_destroy(server_handle);
	krb5_free_principal(context, princ);

	return (PAM_SUCCESS);
}

/*
 * exp_warn
 *
 * Warn the user if their pw is set to expire.
 *
 * We first check to see if the KDC had set any account or password
 * expiration information in the key expiration field.  If this was
 * not set then we must assume that the KDC could be broken and revert
 * to fetching pw/account expiration information from kadm.  We can not
 * determine the difference between broken KDCs that do not send key-exp
 * vs. principals that do not have an expiration policy.  The up-shot
 * is that pam_krb5 will probably not be stacked for acct mgmt if the
 * environment does not have an exp policy, avoiding the second exchange
 * using the kadm protocol.
 */
static int
exp_warn(
	pam_handle_t *pamh,
	const char *user,
	krb5_module_data_t *kmd,
	int debug)

{
	int err;
	kadm5_principal_ent_rec prent;
	krb5_timestamp  now, days, expiration;
	char    messages[PAM_MAX_NUM_MSG][PAM_MAX_MSG_SIZE], *password;
	krb5_error_code code;

	if (debug)
		__pam_log(LOG_AUTH | LOG_DEBUG,
		    "PAM-KRB5 (acct): exp_warn start: user = '%s'",
		    user ? user : "<null>");

	password = kmd->password;

	if (!pamh || !user || !password) {
		err = PAM_SERVICE_ERR;
		goto exit;
	}

	/*
	 * If we error out from krb5_init_secure_context, then just set error
	 * code, check to see about debug message and exit out of routine as the
	 * context could not possibly have been setup.
	 */

	if (code = krb5_init_secure_context(&kmd->kcontext)) {
		err = PAM_SYSTEM_ERR;
		if (debug)
			__pam_log(LOG_AUTH | LOG_ERR, "PAM-KRB5 (acct): "
			    "krb5_init_secure_context failed: code=%d",
			    code);
		goto exit;
	}
	if (code = krb5_timeofday(kmd->kcontext, &now)) {
		err = PAM_SYSTEM_ERR;
		if (debug)
			__pam_log(LOG_AUTH | LOG_ERR,
			    "PAM-KRB5 (acct): krb5_timeofday failed: code=%d",
			    code);
		goto out;
	}

	if (kmd->expiration != 0) {
		expiration = kmd->expiration;
	} else {
		(void) memset(&prent, 0, sizeof (prent));
		if ((err = fetch_princ_entry(kmd, user, &prent, debug))
		    != PAM_SUCCESS) {
			if (debug)
				__pam_log(LOG_AUTH | LOG_DEBUG,
				"PAM-KRB5 (acct): exp_warn: fetch_pr failed %d",
				err);
			goto out;
		}
		if (prent.princ_expire_time != 0 && prent.pw_expiration != 0)
			expiration = min(prent.princ_expire_time,
				prent.pw_expiration);
		else
			expiration = prent.princ_expire_time ?
				prent.princ_expire_time : prent.pw_expiration;
	}

	if (debug)
		__pam_log(LOG_AUTH | LOG_DEBUG,
		    "PAM-KRB5 (acct): exp_warn: "
		    "princ/pw_exp exp=%ld, now =%ld, days=%ld",
		    expiration,
		    now,
		    expiration > 0
		    ? ((expiration - now) / DAY)
		    : 0);

	/* warn user if principal's pw is set to expire */
	if (expiration > 0) {
		days = (expiration - now) / DAY;
		if (days <= 0)
			(void) snprintf(messages[0],
				sizeof (messages[0]),
				dgettext(TEXT_DOMAIN,
				"Your Kerberos account/password will expire "
				"within 24 hours.\n"));
		else if (days == 1)
			(void) snprintf(messages[0],
				sizeof (messages[0]),
				dgettext(TEXT_DOMAIN,
				"Your Kerberos account/password will expire "
				"in 1 day.\n"));
		else
			(void) snprintf(messages[0],
				sizeof (messages[0]),
				dgettext(TEXT_DOMAIN,
				"Your Kerberos account/password will expire in "
				"%d days.\n"),
				(int)days);

		(void) __pam_display_msg(pamh, PAM_TEXT_INFO, 1,
					messages, NULL);
	}

	/* things went smooth */
	err = PAM_SUCCESS;

out:

	if (kmd->kcontext) {
		krb5_free_context(kmd->kcontext);
		kmd->kcontext = NULL;
	}

exit:

	if (debug)
		__pam_log(LOG_AUTH | LOG_DEBUG,
		    "PAM-KRB5 (acct): exp_warn end: err = %d", err);

	return (err);
}

/*
 * pam_krb5 acct_mgmt
 *
 * we do
 *    - check if pw expired (flag set in auth)
 *    - warn user if pw is set to expire
 *
 * notes
 *    - we require the auth module to have already run (sets module data)
 *    - we don't worry about an expired princ cuz if that's the case,
 *      auth would have failed
 */
int
pam_sm_acct_mgmt(pam_handle_t *pamh, int flags, int argc, const char **argv)
{
	const char *user = NULL;
	char *userdata = NULL;
	int err;
	int i;
	krb5_module_data_t *kmd = NULL;
	char messages[PAM_MAX_NUM_MSG][PAM_MAX_MSG_SIZE];
	int debug = 0;  /* pam.conf entry option */
	int nowarn = 0; /* pam.conf entry option, no expire warnings */
	const pam_repository_t *rep_data = NULL;

	for (i = 0; i < argc; i++) {
		if (strcasecmp(argv[i], "debug") == 0)
			debug = 1;
		else if (strcasecmp(argv[i], "nowarn") == 0) {
			nowarn = 1;
			flags = flags | PAM_SILENT;
		} else {
			__pam_log(LOG_AUTH | LOG_ERR,
			    "PAM-KRB5 (acct): illegal option %s",
			    argv[i]);
		}
	}

	if (debug)
		__pam_log(LOG_AUTH | LOG_DEBUG,
		    "PAM-KRB5 (acct): debug=%d, nowarn=%d",
		    debug, nowarn);

	(void) pam_get_item(pamh, PAM_REPOSITORY, (const void **)&rep_data);

	if (rep_data != NULL) {
		/*
		 * If the repository is not ours,
		 * return PAM_IGNORE.
		 */
		if (strcmp(rep_data->type, KRB5_REPOSITORY_NAME) != 0) {
			if (debug)
				__pam_log(LOG_AUTH | LOG_DEBUG,
					"PAM-KRB5 (acct): wrong"
					"repository found (%s), returning "
					"PAM_IGNORE", rep_data->type);
			return (PAM_IGNORE);
		}
	}


	/* get user name */
	(void) pam_get_item(pamh, PAM_USER, (const void **)&user);

	if (user == NULL || *user == '\0') {
		err = PAM_USER_UNKNOWN;
		goto out;
	}

	/* get pam_krb5_migrate specific data */
	err = pam_get_data(pamh, KRB5_AUTOMIGRATE_DATA,
					(const void **)&userdata);
	if (err != PAM_SUCCESS) {
		if (debug)
			__pam_log(LOG_AUTH | LOG_DEBUG, "PAM-KRB5 (acct): "
				"no module data for KRB5_AUTOMIGRATE_DATA");
	} else {
		/*
		 * We try and reauthenticate, since this user has a
		 * newly created krb5 principal via the pam_krb5_migrate
		 * auth module. That way, this new user will have fresh
		 * creds (assuming pam_sm_authenticate() succeeds).
		 */
		if (strcmp(user, userdata) == 0)
			(void) pam_sm_authenticate(pamh, flags, argc, argv);
		else
			if (debug)
				__pam_log(LOG_AUTH | LOG_DEBUG,
				"PAM-KRB5 (acct): PAM_USER %s"
				"does not match user %s from pam_get_data()",
				user, (char *)userdata);
	}

	/* get krb5 module data  */
	if ((err = pam_get_data(pamh, KRB5_DATA, (const void **)&kmd))
	    != PAM_SUCCESS) {
		if (err == PAM_NO_MODULE_DATA) {
			/*
			 * pam_auth never called (possible config
			 * error; no pam_krb5 auth entry in pam.conf),
			 */
			if (debug) {
				__pam_log(LOG_AUTH | LOG_DEBUG,
				    "PAM-KRB5 (acct): no module data");
			}
			err = PAM_IGNORE;
			goto out;
		} else {
			__pam_log(LOG_AUTH | LOG_ERR,
				    "PAM-KRB5 (acct): get module"
				    " data failed: err=%d",
			    err);
		}
		goto out;
	}

	debug = debug || kmd->debug;

	/*
	 * auth mod set status to ignore, most likely cuz root key is
	 * in keytab, so skip other checks and return ignore
	 */
	if (kmd->auth_status == PAM_IGNORE) {
		if (debug)
			__pam_log(LOG_AUTH | LOG_DEBUG,
			    "PAM-KRB5 (acct): kmd auth_status is IGNORE");
		err = PAM_IGNORE;
		goto out;
	}

	/*
	 * If there is no Kerberos related user and there is authentication
	 * data, this means that while the user has successfully passed
	 * authentication, Kerberos is not the account authority because there
	 * is no valid Kerberos principal.  PAM_IGNORE is returned since
	 * Kerberos is not authoritative for this user.  Other modules in the
	 * account stack will need to determine the success or failure for this
	 * user.
	 */
	if (kmd->auth_status == PAM_USER_UNKNOWN) {
		if (debug)
			syslog(LOG_DEBUG,
			    "PAM-KRB5 (acct): kmd auth_status is USER UNKNOWN");
		err = PAM_IGNORE;
		goto out;
	}

	/*
	 * age_status will be set to PAM_NEW_AUTHTOK_REQD in pam_krb5's
	 * 'auth' if the user's key/pw has expired and needs to be changed
	 */
	if (kmd->age_status == PAM_NEW_AUTHTOK_REQD) {
		if (!nowarn) {
			(void) snprintf(messages[0], sizeof (messages[0]),
				dgettext(TEXT_DOMAIN,
				"Your Kerberos password has expired.\n"));
			(void) __pam_display_msg(pamh, PAM_TEXT_INFO,
					1, messages, NULL);
		}
		err = PAM_NEW_AUTHTOK_REQD;
		goto out;
	}

	if (kmd->auth_status == PAM_SUCCESS && !(flags & PAM_SILENT) &&
	    !nowarn && kmd->password) {
		/* if we fail, let it slide, it's only a warning brah */
		(void) exp_warn(pamh, user, kmd, debug);
	}

	/*
	 * If Kerberos is treated as optional in the PAM stack, it is possible
	 * that there is a KRB5_DATA item and a non-Kerberos account authority.
	 * In that case, PAM_IGNORE is returned.
	 */
	err = kmd->auth_status != PAM_SUCCESS ? PAM_IGNORE : kmd->auth_status;

out:
	if (debug)
		__pam_log(LOG_AUTH | LOG_DEBUG,
		    "PAM-KRB5 (acct): end: %s", pam_strerror(pamh, err));

	return (err);
}