/*
 * 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 <stdlib.h>
#include <pwd.h>
#include <shadow.h>
#include <syslog.h>
#include <errno.h>
#include <string.h>
#include <crypt.h>
#include <unistd.h>
#include <user_attr.h>
#include <auth_attr.h>
#include <userdefs.h>
#include <deflt.h>
#include <sys/stat.h>
#include <sys/param.h>
#include <stdarg.h>

#include <security/pam_appl.h>
#include <security/pam_modules.h>
#include <security/pam_impl.h>

#include <libintl.h>

#include <passwdutil.h>

#define LOGINADMIN      "/etc/default/login"
#define MAXTRYS         5

/*PRINTFLIKE2*/
void
error(pam_handle_t *pamh, char *fmt, ...)
{
        va_list ap;
        char messages[1][PAM_MAX_MSG_SIZE];

        va_start(ap, fmt);
        (void) vsnprintf(messages[0], sizeof (messages[0]), fmt, ap);
        (void) __pam_display_msg(pamh, PAM_ERROR_MSG, 1, messages, NULL);
        va_end(ap);
}

static int
get_max_failed(const char *user)
{
        char *val = NULL;
        userattr_t *uattr;
        int do_lock = 0;
        int retval = 0;
        char *p;
        void    *defp;

        if ((uattr = getusernam(user)) != NULL)
                val = kva_match(uattr->attr, USERATTR_LOCK_AFTER_RETRIES_KW);

        if (val != NULL) {
                do_lock = (strcasecmp(val, "yes") == 0);
        } else if ((defp = defopen_r(AUTH_POLICY)) != NULL) {
                int flags;
                flags = defcntl_r(DC_GETFLAGS, 0, defp);
                TURNOFF(flags, DC_CASE);
                (void) defcntl_r(DC_SETFLAGS, flags, defp);
                if ((p = defread_r("LOCK_AFTER_RETRIES=", defp)) != NULL)
                        do_lock = (strcasecmp(p, "yes") == 0);
                defclose_r(defp);
        }

        if (uattr != NULL)
                free_userattr(uattr);

        if (do_lock) {
                retval = MAXTRYS;
                if ((defp = defopen_r(LOGINADMIN)) != NULL) {
                        if ((p = defread_r("RETRIES=", defp)) != NULL)
                                retval = atoi(p);
                        defclose_r(defp);
                }
        }

        return (retval);
}

static void
display_warning(pam_handle_t *pamh, int failures, char *homedir)
{
        char hushpath[MAXPATHLEN];
        struct stat buf;

        (void) snprintf(hushpath, sizeof (hushpath), "%s/.hushlogin", homedir);
        if (stat(hushpath, &buf) == 0)
                return;

        if (failures == 1)
                error(pamh, "Warning: 1 failed login attempt since last "
                    "successful login.");
        else if (failures < FAILCOUNT_MASK)
                error(pamh, "Warning: %d failed login attempts since last "
                    "successful login.", failures);
        else
                error(pamh, "Warning: at least %d failed login attempts since "
                    "last successful login.", failures);
}

/*
 * int pam_sm_authenticate(pamh, flags, arc, argv)
 *
 * This routine verifies that the password as stored in the
 * PAM_AUTHTOK item is indeed the password that belongs to the user
 * as stored in PAM_USER.
 *
 * This routine will not establish Secure RPC Credentials, the pam_dhkeys
 * module should be stacked before us if Secure RPC Credentials are needed
 * to obtain passwords.
 */
int
pam_sm_authenticate(pam_handle_t *pamh, int flags, int argc, const char **argv)
{
        int i;
        int debug = 0;
        int nowarn = (flags & PAM_SILENT) != 0;
        const char *user;
        const char *passwd;
        char *rep_passwd;
        char *crypt_passwd;
        char *repository_name;
        const struct pam_repository *auth_rep;
        pwu_repository_t *pwu_rep;
        attrlist attr_pw[4];
        int result;
        int server_policy = 0;
        int old_failed_count;
        char *homedir = NULL;
        int dolock = 1;

        for (i = 0; i < argc; i++) {
                if (strcmp(argv[i], "debug") == 0)
                        debug = 1;
                else if (strcmp(argv[i], "nowarn") == 0)
                        nowarn = 1;
                else if (strcmp(argv[i], "server_policy") == 0)
                        server_policy = 1;
                else if (strcmp(argv[i], "nolock") == 0)
                        dolock = 0;
        }

        if (debug)
                __pam_log(LOG_AUTH | LOG_DEBUG,
                    "pam_unix_auth: entering pam_sm_authenticate()");

        if (pam_get_item(pamh, PAM_USER, (const void **)&user) != PAM_SUCCESS) {
                __pam_log(LOG_AUTH | LOG_DEBUG, "pam_unix_auth: USER not set");
                return (PAM_SYSTEM_ERR);
        }

        if (user == NULL || *user == '\0') {
                __pam_log(LOG_AUTH | LOG_DEBUG,
                    "pam_unix_auth: USER NULL or empty!\n");
                return (PAM_USER_UNKNOWN);
        }

        if (pam_get_item(pamh, PAM_AUTHTOK, (const void **)&passwd) !=
            PAM_SUCCESS) {
                __pam_log(LOG_AUTH | LOG_DEBUG,
                    "pam_unix_auth: AUTHTOK not set!\n");
                return (PAM_SYSTEM_ERR);
        }

        result = pam_get_item(pamh, PAM_REPOSITORY, (const void **)&auth_rep);
        if (result == PAM_SUCCESS && auth_rep != NULL) {
                if ((pwu_rep = calloc(1, sizeof (*pwu_rep))) == NULL)
                        return (PAM_BUF_ERR);
                pwu_rep->type = auth_rep->type;
                pwu_rep->scope = auth_rep->scope;
                pwu_rep->scope_len = auth_rep->scope_len;
        } else {
                pwu_rep = PWU_DEFAULT_REP;
        }

        /*
         * Get password and the name of the repository where the
         * password resides.
         */
        attr_pw[0].type = ATTR_PASSWD;          attr_pw[0].next = &attr_pw[1];
        attr_pw[1].type = ATTR_REP_NAME;        attr_pw[1].next = &attr_pw[2];
        /*
         * Also get the current number of failed logins; we use
         * this later to determine whether we need to reset the count
         * on a succesful authentication. We use the home-directory
         * to look for .hushlogin in order to optionaly surpress the
         * "failed attempts" message.
         */
        attr_pw[2].type = ATTR_FAILED_LOGINS;   attr_pw[2].next = &attr_pw[3];
        attr_pw[3].type = ATTR_HOMEDIR;         attr_pw[3].next = NULL;

        result = __get_authtoken_attr(user, pwu_rep, attr_pw);

        if (pwu_rep != PWU_DEFAULT_REP)
                free(pwu_rep);

        if (result == PWU_NOT_FOUND) {
                __pam_log(LOG_AUTH | LOG_DEBUG,
                    "pam_unix_auth: user %s not found\n", user);
                return (PAM_USER_UNKNOWN);
        }

        if (result == PWU_DENIED) {
                __pam_log(LOG_AUTH | LOG_DEBUG,
                    "pam_unix_auth: failed to obtain attributes");
                return (PAM_PERM_DENIED);
        }

        if (result != PWU_SUCCESS)
                return (PAM_SYSTEM_ERR);

        rep_passwd = attr_pw[0].data.val_s;
        repository_name = attr_pw[1].data.val_s;
        old_failed_count = attr_pw[2].data.val_i;
        homedir = attr_pw[3].data.val_s;

        /*
         * Chop off old SunOS-style password aging information.
         *
         * Note: old style password aging is only defined for UNIX-style
         *       crypt strings, hence the comma will always be at position 14.
         * Note: This code is here because some other vendors might still
         *       support this style of password aging. If we don't remove
         *       the age field, no one will be able to login.
         * XXX   yank this code when we're certain this "compatibility"
         *       isn't needed anymore.
         */
        if (rep_passwd != NULL && rep_passwd[0] != '$' &&
            strlen(rep_passwd) > 13 && rep_passwd[13] == ',')
                rep_passwd[13] = '\0';

        /* Is a password check required? */
        if (rep_passwd == NULL || *rep_passwd == '\0') {
                if (flags & PAM_DISALLOW_NULL_AUTHTOK) {
                        result = PAM_AUTH_ERR;
                        __pam_log(LOG_AUTH | LOG_NOTICE,
                            "pam_unix_auth: empty password for %s not allowed.",
                            user);
                        goto out;
                } else {
                        result = PAM_SUCCESS;
                        goto out;
                }
        }

        /*
         * Password check *is* required. Make sure we have a valid
         * pointer in PAM_AUTHTOK
         */
        if (passwd == NULL) {
                result = PAM_AUTH_ERR;
                goto out;
        }

        if (server_policy &&
            strcmp(repository_name, "files") != 0 &&
            strcmp(repository_name, "nis") != 0) {
                result = PAM_IGNORE;
                goto out;
        }

        /* Now check the entered password */
        if ((crypt_passwd = crypt(passwd, rep_passwd)) == NULL) {
                switch (errno) {
                case ENOMEM:
                        result = PAM_BUF_ERR;
                        break;
                case ELIBACC:
                        result = PAM_OPEN_ERR;
                        break;
                default:
                        result = PAM_SYSTEM_ERR;
                }
                goto out;
        }

        if (strcmp(crypt_passwd, rep_passwd) == 0)
                result = PAM_SUCCESS;
        else
                result = PAM_AUTH_ERR;

        /* Clear or increment failed failed count */
        if (dolock && (result == PAM_SUCCESS && old_failed_count > 0)) {
                old_failed_count = __rst_failed_count(user, repository_name);
                if (nowarn == 0 && old_failed_count > 0)
                        display_warning(pamh, old_failed_count, homedir);
        } else if (dolock && result == PAM_AUTH_ERR) {
                int max_failed = get_max_failed(user);
                if (max_failed != 0) {
                        if (__incr_failed_count(user, repository_name,
                            max_failed) == PWU_ACCOUNT_LOCKED)
                                result = PAM_MAXTRIES;
                }
        }
out:
        if (rep_passwd)
                free(rep_passwd);
        if (repository_name)
                free(repository_name);
        if (homedir)
                free(homedir);
        return (result);
}

/*ARGSUSED*/
int
pam_sm_setcred(pam_handle_t *pamh, int flags, int argc, const char **argv)
{
        return (PAM_IGNORE);
}