/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */

/* kdc/policy.c - Policy decision routines for KDC */

/*

 * Copyright (C) 2017 by Red Hat, Inc.

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 * * Redistributions of source code must retain the above copyright

 *   notice, this list of conditions and the following disclaimer.

 *

 * * Redistributions in binary form must reproduce the above copyright

 *   notice, this list of conditions and the following disclaimer in

 *   the documentation and/or other materials provided with the

 *   distribution.

 *

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS

 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE

 * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,

 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES

 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR

 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,

 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED

 * OF THE POSSIBILITY OF SUCH DAMAGE.

 */

#include "k5-int.h"

#include "kdc_util.h"

#include "extern.h"

#include "policy.h"

#include "adm_proto.h"

#include <krb5/kdcpolicy_plugin.h>

#include <syslog.h>

typedef struct kdcpolicy_handle_st {

    struct krb5_kdcpolicy_vtable_st vt;

    krb5_kdcpolicy_moddata moddata;

} *kdcpolicy_handle;

static kdcpolicy_handle *handles;

static void

free_indicators(char **ais)

{

    size_t i;

    if (ais == NULL)

        return;

    for (i = 0; ais[i] != NULL; i++)

        free(ais[i]);

    free(ais);

}

/* Convert inds to a null-terminated list of C strings. */

static krb5_error_code

authind_strings(krb5_data *const *inds, char ***strs_out)

{

    krb5_error_code ret;

    char **list = NULL;

    size_t i, count;

    *strs_out = NULL;

    for (count = 0; inds != NULL && inds[count] != NULL; count++);

    list = k5calloc(count + 1, sizeof(*list), &ret;;

    if (list == NULL)

        goto error;

    for (i = 0; i < count; i++) {

        list[i] = k5memdup0(inds[i]->data, inds[i]->length, &ret;;

        if (list[i] == NULL)

            goto error;

    }

    *strs_out = list;

    return 0;

error:

    free_indicators(list);

    return ret;

}

/* Constrain times->endtime to life and times->renew_till to rlife, relative to

 * now. */

static void

update_ticket_times(krb5_ticket_times *times, krb5_timestamp now,

                    krb5_deltat life, krb5_deltat rlife)

{

    if (life)

        times->endtime = ts_min(ts_incr(now, life), times->endtime);

    if (rlife)

        times->renew_till = ts_min(ts_incr(now, rlife), times->renew_till);

}

/* Check an AS request against kdcpolicy modules, updating times with any

 * module endtime constraints.  Set an appropriate status string on error. */

krb5_error_code

check_kdcpolicy_as(krb5_context context, const krb5_kdc_req *request,

                   const krb5_db_entry *client, const krb5_db_entry *server,

                   krb5_data *const *auth_indicators, krb5_timestamp kdc_time,

                   krb5_ticket_times *times, const char **status)

{

    krb5_deltat life = 0, rlife = 0;

    krb5_error_code ret;

    kdcpolicy_handle *hp, h;

    char **ais = NULL;

    *status = NULL;

    ret = authind_strings(auth_indicators, &ais);

    if (ret)

        goto done;

    for (hp = handles; *hp != NULL; hp++) {

        h = *hp;

        if (h->vt.check_as == NULL)

            continue;

        ret = h->vt.check_as(context, h->moddata, request, client, server,

                             (const char **)ais, status, &life, &rlife);

        if (ret)

            goto done;

        update_ticket_times(times, kdc_time, life, rlife);

    }

done:

    free_indicators(ais);

    return ret;

}

/*

 * Check the TGS request against the local TGS policy.  Accepts an

 * authentication indicator for the module policy decisions.  Returns 0 and a

 * NULL status string on success.

 */

krb5_error_code

check_kdcpolicy_tgs(krb5_context context, const krb5_kdc_req *request,

                    const krb5_db_entry *server, const krb5_ticket *ticket,

                    krb5_data *const *auth_indicators, krb5_timestamp kdc_time,

                    krb5_ticket_times *times, const char **status)

{

    krb5_deltat life = 0, rlife = 0;

    krb5_error_code ret;

    kdcpolicy_handle *hp, h;

    char **ais = NULL;

    *status = NULL;

    ret = authind_strings(auth_indicators, &ais);

    if (ret)

        goto done;

    for (hp = handles; *hp != NULL; hp++) {

        h = *hp;

        if (h->vt.check_tgs == NULL)

            continue;

        ret = h->vt.check_tgs(context, h->moddata, request, server, ticket,

                              (const char **)ais, status, &life, &rlife);

        if (ret)

            goto done;

        update_ticket_times(times, kdc_time, life, rlife);

    }

done:

    free_indicators(ais);

    return ret;

}

void

unload_kdcpolicy_plugins(krb5_context context)

{

    kdcpolicy_handle *hp, h;

    for (hp = handles; *hp != NULL; hp++) {

        h = *hp;

        if (h->vt.fini != NULL)

            h->vt.fini(context, h->moddata);

        free(h);

    }

    free(handles);

    handles = NULL;

}

krb5_error_code

load_kdcpolicy_plugins(krb5_context context)

{

    krb5_error_code ret;

    krb5_plugin_initvt_fn *modules = NULL, *mod;

    kdcpolicy_handle h;

    size_t count;

    ret = k5_plugin_load_all(context, PLUGIN_INTERFACE_KDCPOLICY, &modules);

    if (ret)

        goto cleanup;

    for (count = 0; modules[count] != NULL; count++);

    handles = k5calloc(count + 1, sizeof(*handles), &ret;;

    if (handles == NULL)

        goto cleanup;

    count = 0;

    for (mod = modules; *mod != NULL; mod++) {

        h = k5calloc(1, sizeof(*h), &ret;;

        if (h == NULL)

            goto cleanup;

        ret = (*mod)(context, 1, 1, (krb5_plugin_vtable)&h->vt);

        if (ret) {              /* Version mismatch. */

            TRACE_KDCPOLICY_VTINIT_FAIL(context, ret);

            free(h);

            continue;

        }

        if (h->vt.init != NULL) {

            ret = h->vt.init(context, &h->moddata);

            if (ret == KRB5_PLUGIN_NO_HANDLE) {

                TRACE_KDCPOLICY_INIT_SKIP(context, h->vt.name);

                free(h);

                continue;

            }

            if (ret) {

                kdc_err(context, ret, _("while loading policy module %s"),

                        h->vt.name);

                free(h);

                goto cleanup;

            }

        }

        handles[count++] = h;

    }

    ret = 0;

cleanup:

    if (ret)

        unload_kdcpolicy_plugins(context);

    k5_plugin_free_modules(context, modules);

    return ret;

}