/*
 * 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 2006 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 *
 * Copyright 2023 OmniOS Community Edition (OmniOSce) Association.
 */

#include <crypt.h>
#include <pwd.h>
#include <shadow.h>
#include <string.h>
#include <stdlib.h>
#include <syslog.h>
#include <security/pam_appl.h>
#include <security/pam_modules.h>
#include "../../libpam/pam_impl.h"

#include <libintl.h>

/*
 * Various useful files and string constants
 */
#define DIAL_FILE       "/etc/dialups"
#define DPASS_FILE      "/etc/d_passwd"
#define SHELL           "/usr/bin/sh"
#define SCPYN(a, b)     (void) strncpy(a, b, sizeof (a))

/*
 * pam_sm_authenticate  - This is the top level function in the
 *                      module called by pam_auth_port in the framework
 *                      Returns: PAM_AUTH_ERR on failure, 0 on success
 */
int
pam_sm_authenticate(pam_handle_t *pamh, int flags, int argc, const char **argv)
{
        const char *ttyn, *user;
        FILE *fp;
        char defpass[30];
        char line[80];
        char *p1 = NULL, *p2 = NULL;
        struct passwd pwd;
        char pwd_buffer[1024];
        char *password = NULL;
        int retcode;
        int i;
        int debug = 0;
        int res;

        for (i = 0; i < argc; i++) {
                if (strcasecmp(argv[i], "debug") == 0)
                        debug = 1;
                else
                        syslog(LOG_DEBUG, "illegal option %s", argv[i]);
        }

        if ((retcode = pam_get_user(pamh, &user, NULL))
                                        != PAM_SUCCESS ||
            (retcode = pam_get_item(pamh, PAM_TTY, (const void **)&ttyn))
                                        != PAM_SUCCESS)
                return (retcode);

        if (debug) {
                syslog(LOG_DEBUG,
                        "Dialpass authenticate user = %s, ttyn = %s",
                        user ? user : "NULL", ttyn ? ttyn : "NULL");
        }

        if (ttyn == NULL || *ttyn == '\0') {
                const char *service;

                (void) pam_get_item(pamh, PAM_SERVICE, (const void **)&service);
                syslog(LOG_ERR, "pam_dial_auth: terminal-device not specified"
                    "by %s, returning %s.", service,
                    pam_strerror(pamh, PAM_SERVICE_ERR));
                return (PAM_SERVICE_ERR);
        }
        if (getpwnam_r(user, &pwd, pwd_buffer, sizeof (pwd_buffer)) == NULL)
                return (PAM_USER_UNKNOWN);

        if ((fp = fopen(DIAL_FILE, "rF")) == NULL)
                return (PAM_IGNORE);

        while ((p1 = fgets(line, sizeof (line), fp)) != NULL) {
                while (*p1 != '\n' && *p1 != ' ' && *p1 != '\t')
                        p1++;
                *p1 = '\0';
                if (strcmp(line, ttyn) == 0)
                        break;
        }

        (void) fclose(fp);

        if ((fp = fopen(DPASS_FILE, "rF")) == NULL) {
                syslog(LOG_ERR, "pam_dial_auth: %s without %s, returning %s.",
                    DIAL_FILE, DPASS_FILE,
                    pam_strerror(pamh, PAM_SYSTEM_ERR));
                (void) memset(line, 0, sizeof (line));
                return (PAM_SYSTEM_ERR);
        }

        if (p1 == NULL) {
                (void) fclose(fp);
                (void) memset(line, 0, sizeof (line));
                return (PAM_IGNORE);
        }

        defpass[0] = '\0';

        while ((p1 = fgets(line, sizeof (line)-1, fp)) != NULL) {
                while (*p1 && *p1 != ':')
                        p1++;
                *p1++ = '\0';
                p2 = p1;
                while (*p1 && *p1 != ':')
                        p1++;
                *p1 = '\0';
                if (pwd.pw_shell != NULL && strcmp(pwd.pw_shell, line) == 0)
                        break;

                if (strcmp(SHELL, line) == 0)
                        SCPYN(defpass, p2);
                p2 = NULL;
        }

        (void) memset(line, 0, sizeof (line));
        (void) fclose(fp);

        if (p2 == NULL)
                p2 = defpass;

        if (*p2 != '\0') {
                res = __pam_get_authtok(pamh, PAM_PROMPT, PAM_AUTHTOK,
                    dgettext(TEXT_DOMAIN, "Dialup Password: "), &password);

                if (res != PAM_SUCCESS) {
                        return (res);
                }

                if (strcmp(crypt(password, p2), p2) != 0) {
                        (void) memset(password, 0, strlen(password));
                        free(password);
                        return (PAM_AUTH_ERR);
                }
                (void) memset(password, 0, strlen(password));
                free(password);
        }

        return (PAM_SUCCESS);
}

/*
 * dummy pam_sm_setcred - does nothing
 */
/*ARGSUSED*/
int
pam_sm_setcred(pam_handle_t *pamh, int flags, int argc, const char **argv)
{
        return (PAM_IGNORE);
}