/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (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 2003 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 *
 * Copyright 2023 OmniOS Community Edition (OmniOSce) Association.
 */

#include <security/pam_appl.h>
#include <security/pam_modules.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <pwd.h>
#include <syslog.h>
#include <libintl.h>

#include "sample_utils.h"

/*
 *
 * Sample module for pam_sm_authenticate.
 *
 * options -
 *
 *      debug
 *      use_first_pass
 *      try_first_pass
 *      first_pass_good  (first password is always good when used with use/try)
 *      first_pass_bad   (first password is always bad when used with use/try)
 *      pass=foobar      (set good password to "foobar". default good password
 *                       is test)
 *      always_fail      always return PAM_AUTH_ERR
 *      always_succeed   always return PAM_SUCCESS
 *      always_ignore
 *
 *
 */

/*
 * pam_sm_authenticate          - Authenticate user
 */
int
pam_sm_authenticate(pam_handle_t *pamh, int flags, int argc, const char **argv)
{
        const char *user;
        const struct pam_conv *pam_convp;
        int err, result = PAM_AUTH_ERR;
        struct pam_response *ret_resp = (struct pam_response *)0;
        char messages[PAM_MAX_NUM_MSG][PAM_MAX_MSG_SIZE];
        int debug = 0;
        int try_first_pass = 0;
        int use_first_pass = 0;
        int first_pass_good = 0;
        int first_pass_bad = 0;
        int i, num_msg;
        const char *firstpass;
        char *password;
        char the_password[64];

        if (debug)
                syslog(LOG_DEBUG, "Sample Authentication\n");

        (void) strcpy(the_password, "test");

        for (i = 0; i < argc; i++) {
                if (strcmp(argv[i], "debug") == 0)
                        debug = 1;
                else if (strcmp(argv[i], "try_first_pass") == 0)
                        try_first_pass = 1;
                else if (strcmp(argv[i], "first_pass_good") == 0)
                        first_pass_good = 1;
                else if (strcmp(argv[i], "first_pass_bad") == 0)
                        first_pass_bad = 1;
                else if (strcmp(argv[i], "use_first_pass") == 0)
                        use_first_pass = 1;
                else if (strcmp(argv[i], "always_fail") == 0)
                        return (PAM_AUTH_ERR);
                else if (strcmp(argv[i], "always_succeed") == 0)
                        return (PAM_SUCCESS);
                else if (strcmp(argv[i], "always_ignore") == 0)
                        return (PAM_IGNORE);
                else if (sscanf(argv[i], "pass=%64s", the_password) == 1) {
                        /*EMPTY*/;
                }
                else
                        syslog(LOG_DEBUG, "illegal scheme option %s", argv[i]);
        }

        err = pam_get_user(pamh, &user, NULL);
        if (err != PAM_SUCCESS)
                return (err);

        err = pam_get_item(pamh, PAM_CONV, (const void**)&pam_convp);
        if (err != PAM_SUCCESS)
                return (err);

        (void) pam_get_item(pamh, PAM_AUTHTOK, (const void **)&firstpass);

        if (firstpass && (use_first_pass || try_first_pass)) {

                if ((first_pass_good ||
                        strncmp(firstpass, the_password,
                                strlen(the_password)) == 0) &&
                                !first_pass_bad) {
                                        result = PAM_SUCCESS;
                                        goto out;
                }
                if (use_first_pass) goto out;
        }

        /*
         * Get the password from the user
         */
        if (firstpass) {
                (void) snprintf(messages[0], sizeof (messages[0]),
                        dgettext(TEXT_DOMAIN, "TEST Password: "));
        } else {
                (void) snprintf(messages[0], sizeof (messages[0]),
                        dgettext(TEXT_DOMAIN, "Password: "));
        }
        num_msg = 1;
        err = __get_authtok(pam_convp->conv,
                                num_msg, messages, NULL, &ret_resp);

        if (err != PAM_SUCCESS) {
                result = err;
                goto out;
        }

        password = ret_resp->resp;

        if (password == NULL) {
                result = PAM_AUTH_ERR;
                goto out;
        }

        /* one last ditch attempt to "login" to TEST */

        if (strncmp(password, the_password, strlen(the_password)) == 0) {
                result = PAM_SUCCESS;
                if (firstpass == NULL) {
                        /* this is the first password, stash it away */
                        (void) pam_set_item(pamh, PAM_AUTHTOK, password);
                }
        }

out:
        if (num_msg > 0) {
                if (ret_resp != 0) {
                        if (ret_resp->resp != 0) {
                                /* avoid leaving password cleartext around */
                                (void) memset(ret_resp->resp, 0,
                                        strlen(ret_resp->resp));
                        }
                        __free_resp(num_msg, ret_resp);
                        ret_resp = 0;
                }
        }

        return (result);
}