pam_modules/authtok_get/authtok_get.c

/*
 * 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 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#include <sys/varargs.h>
#include <string.h>
#include <stdlib.h>
#include <syslog.h>

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

#include <sys/note.h>

#include <libintl.h>

#include <passwdutil.h>

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

int
read_authtok(pam_handle_t *pamh, int debug)
{
    int res;
    char *authtok;
    char *pwd;

    /*
     * We are about to read the new AUTHTOK. Store the AUTHTOK that
     * the user used to authenticate in OLDAUTHTOK, so it is available
     * to future modules. If OLDAUTHTOK is already set, we leave it alone
     */

    res = pam_get_item(pamh, PAM_OLDAUTHTOK, (void **)&authtok);
    if (res != PAM_SUCCESS)
        return (res);

    if (authtok == NULL) {
        res = pam_get_item(pamh, PAM_AUTHTOK, (void **)&authtok);
        if (res != PAM_SUCCESS)
            return (res);
        if (authtok != NULL) {
            res = pam_set_item(pamh, PAM_OLDAUTHTOK,
                (void *)authtok);
            if (res == PAM_SUCCESS)
                res = pam_set_item(pamh, PAM_AUTHTOK, NULL);

            if (debug)
                __pam_log(LOG_AUTH | LOG_DEBUG,
                    "read_authtok: Copied AUTHTOK to "
                    "OLDAUTHTOK");

            if (res != PAM_SUCCESS)
                goto out;
        }
    } else {
        /*
         * OLDAUTHTOK was filled in. If AUTHTOK is also filled
         * in, we either succeed a module that has done our
         * work, or we're here because one of the modules
         * that are stacked beyond us has returned PAM_TRY_AGAIN.
         * In either case, we should *not* prompt for another
         * password.
         */
        res = pam_get_item(pamh, PAM_AUTHTOK, (void **)&pwd);
        if (res != PAM_SUCCESS)
            goto out;
        if (pwd != NULL) {
            goto out;
        }
    }

    /*
     * Make sure PAM_AUTHTOK is empty, or the framework will not
     * put the value read by __pam_get_authtok into it
     */
    (void) pam_set_item(pamh, PAM_AUTHTOK, NULL);

    res = __pam_get_authtok(pamh, PAM_PROMPT, PAM_AUTHTOK,
        dgettext(TEXT_DOMAIN, "New Password: "), &pwd);

    if (res != PAM_SUCCESS)
        goto out;

    if (pwd == NULL) {
        char *service;
        if ((pam_get_item(pamh, PAM_SERVICE, (void **)&service) ==
            PAM_SUCCESS) && service != NULL) {
            error(pamh, dgettext(TEXT_DOMAIN, "%s: Sorry."),
                service);
        }
        res = PAM_PERM_DENIED;
    } else {
        (void) memset(pwd, 0, strlen(pwd));
        free(pwd);
    }
out:
    if (res != PAM_SUCCESS) {
        (void) pam_set_item(pamh, PAM_AUTHTOK, NULL);
        (void) pam_set_item(pamh, PAM_OLDAUTHTOK, NULL);
    } else {
        /*
         * Since we don't actually check the password, we should
         * not return PAM_SUCCESS if everything went OK.
         * We should return PAM_IGNORE instead.
         */
        res = PAM_IGNORE;
    }

    return (res);
}

int
verify_authtok(pam_handle_t *pamh, int debug)
{
    int res;
    char *authtok;
    char *pwd;

    if (debug)
        __pam_log(LOG_AUTH | LOG_DEBUG,
            "pam_authtok_get: verifying authtok");

    /*
     * All we need to do, is make sure that the user re-enters
     * the password correctly.
     */

    res = pam_get_item(pamh, PAM_AUTHTOK, (void **)&authtok);
    if (res != PAM_SUCCESS || authtok == NULL)
        return (PAM_AUTHTOK_ERR);

    res = __pam_get_authtok(pamh, PAM_PROMPT, 0, dgettext(TEXT_DOMAIN,
        "Re-enter new Password: "), &pwd);

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

    if (strcmp(authtok, pwd) != 0) {
        char *service;

        if ((pam_get_item(pamh, PAM_SERVICE, (void **)&service) ==
            PAM_SUCCESS) && service != NULL) {
            error(pamh, dgettext(TEXT_DOMAIN,
                "%s: They don't match."), service);
        }
        (void) pam_set_item(pamh, PAM_AUTHTOK, NULL);
        (void) memset(pwd, 0, strlen(pwd));
        free(pwd);
        return (PAM_AUTHTOK_ERR);
    }

    if (debug)
        __pam_log(LOG_AUTH | LOG_DEBUG,
            "pam_authtok_get: new password verified");

    (void) memset(pwd, 0, strlen(pwd));
    free(pwd);
    return (PAM_IGNORE);
}

int
pam_sm_chauthtok(pam_handle_t *pamh, int flags, int argc, const char **argv)
{
    int i;
    int debug = 0;
    int res;

    for (i = 0; i < argc; i++)
        if (strcmp(argv[i], "debug") == 0)
            debug = 1;

    if ((flags & PAM_PRELIM_CHECK) == PAM_PRELIM_CHECK)
        res = read_authtok(pamh, debug);
    else
        res = verify_authtok(pamh, debug);

    return (res);
}

/*
 * int pam_sm_authenticate(pamh, flags, argc, argv)
 *
 * Read authentication token from user.
 */
int
pam_sm_authenticate(pam_handle_t *pamh, int flags, int argc, const char **argv)
{

    char    *user;
    char    *password;
    int i;
    int debug = 0;
    int res;
    int fail = 0;

    attrlist al[1];
    pam_repository_t *auth_rep = NULL;
    pwu_repository_t *pwu_rep  = NULL;

    for (i = 0; i < argc; i++)
        if (strcmp(argv[i], "debug") == 0)
            debug = 1;

    if (debug)
        __pam_log(LOG_AUTH | LOG_DEBUG,
            "pam_authtok_get:pam_sm_authenticate: flags = %d", flags);

    if ((res = pam_get_user(pamh, &user, NULL)) != PAM_SUCCESS) {
        if (debug)
            __pam_log(LOG_AUTH | LOG_DEBUG,
                "pam_authtok_get: get user failed: %s",
                pam_strerror(pamh, res));
        return (res);
    }

    if (user == NULL || *user == '\0') {
        __pam_log(LOG_AUTH | LOG_ERR,
            "pam_authtok_get: pam_sm_authenticate: PAM_USER NULL or "
            "empty");
        return (PAM_SYSTEM_ERR);
    }

    res = pam_get_item(pamh, PAM_AUTHTOK, (void **)&password);
    if (res != PAM_SUCCESS)
        return (res);

    if (password != NULL)
        return (PAM_IGNORE);

    /*
     * No password has been entered yet. Check to see if we need
     * to obtain a password
     */

    res = pam_get_item(pamh, PAM_REPOSITORY, (void **)&auth_rep);
    if (res != PAM_SUCCESS) {
        __pam_log(LOG_AUTH | LOG_ERR,
            "pam_authtok_get: error getting repository");
        return (PAM_SYSTEM_ERR);
    }

    if (auth_rep == NULL) {
        pwu_rep = PWU_DEFAULT_REP;
    } else {
        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;
    }

    (void) memset(&al, 0, sizeof (al));
    al[0].type = ATTR_PASSWD;
    al[0].next = NULL;

    res = __get_authtoken_attr(user, pwu_rep, al);

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

    if (res == PWU_SUCCESS &&
        (al[0].data.val_s == NULL || al[0].data.val_s[0] == '\0')) {
        char *service = NULL;
        char *rhost = NULL;

        /*
         * if PAM_DIASALLOW_NULL_AUTHTOK has not been set, we
         * simply return IGNORE
         */
        if ((flags & PAM_DISALLOW_NULL_AUTHTOK) == 0)
            return (PAM_IGNORE);

        /*
         * NULL authtoks are not allowed, so we need to fail.
         * We will ask for a password to mask the failure however.
         */
        (void) pam_get_item(pamh, PAM_RHOST, (void **)&rhost);
        (void) pam_get_item(pamh, PAM_SERVICE, (void **)&service);
        if (service == NULL)
            service = "unknown";
        if (rhost == NULL || *rhost == '\0')
            rhost = "localhost";
        __pam_log(LOG_AUTH | LOG_NOTICE,
            "pam_authtok_get: %s: empty password not allowed for "
            "%s from %s.", service, user, rhost);
        fail = 1;
    }
    if (al[0].data.val_s != NULL) {
        (void) memset(al[0].data.val_s, 0, strlen(al[0].data.val_s));
        free(al[0].data.val_s);
    }

    res = __pam_get_authtok(pamh, PAM_PROMPT, PAM_AUTHTOK,
        dgettext(TEXT_DOMAIN, "Password: "), &password);
    if (res != PAM_SUCCESS)
        return (res);

    if (password != NULL) {
        (void) pam_set_item(pamh, PAM_AUTHTOK, (void *)password);
        (void) memset(password, 0, strlen(password));
        free(password);
    } else if (debug) {
        __pam_log(LOG_AUTH | LOG_DEBUG,
            "pam_authtok_get: pam_sm_authenticate: "
            "got NULL password from get_authtok()");
    }

    if (fail) {
        __pam_log(LOG_AUTH | LOG_DEBUG,
            "pam_authtok_get:pam_sm_authenticate: "
            "failing because NULL authtok not allowed");
        return (PAM_AUTH_ERR);
    } else
        return (PAM_IGNORE);
}

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