/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2008 Isilon Inc http://www.isilon.com/
 * Authors: Doug Rabson <dfr@rabson.org>
 * Developed with Red Inc: Alfred Perlstein <alfred@freebsd.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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 AUTHOR 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 AUTHOR 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 <sys/param.h>
#include <sys/jail.h>
#include <sys/kernel.h>
#include <sys/kobj.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/module.h>
#include <sys/mutex.h>
#include <sys/priv.h>
#include <sys/proc.h>

#include <kgssapi/gssapi.h>
#include <kgssapi/gssapi_impl.h>
#include <rpc/rpc.h>
#include <rpc/rpc_com.h>
#include <rpc/rpcsec_gss.h>

#include "gssd.h"
#include "kgss_if.h"

MALLOC_DEFINE(M_GSSAPI, "GSS-API", "GSS-API");

struct kgss_mech_list kgss_mechs;
struct mtx kgss_gssd_lock;

KGSS_VNET_DEFINE(CLIENT *, kgss_gssd_handle) = NULL;

static int
kgss_load(void)
{
        CLIENT *cl;

        LIST_INIT(&kgss_mechs);

        cl = client_nl_create("kgss", GSSD, GSSDVERS);
        KASSERT(cl, ("%s: netlink client already exist", __func__));

        /*
         * The transport default is no retries at all, since there could
         * be no userland listener to our messages.  We will retry for 5
         * minutes with 10 second interval.  This will potentially cure hosts
         * with misconfigured startup, where kernel starts sending GSS queries
         * before userland had started up the gssd(8) daemon.
         */
        clnt_control(cl, CLSET_RETRIES, &(int){30});
        clnt_control(cl, CLSET_TIMEOUT, &(struct timeval){.tv_sec = 300});

        /*
         * We literally wait on gssd(8), let's see that in top(1).
         */
        clnt_control(cl, CLSET_WAITCHAN, "gssd");

        KGSS_CURVNET_SET_QUIET(KGSS_TD_TO_VNET(curthread));
        mtx_lock(&kgss_gssd_lock);
        KGSS_VNET(kgss_gssd_handle) = cl;
        mtx_unlock(&kgss_gssd_lock);
        KGSS_CURVNET_RESTORE();

        return (0);
}

#if 0
static void
kgss_unload(void)
{

        KGSS_CURVNET_SET_QUIET(KGSS_TD_TO_VNET(curthread));
        clnt_destroy(KGSS_VNET(kgss_gssd_handle));
        KGSS_CURVNET_RESTORE();
}
#endif

int
kgss_oid_equal(const gss_OID oid1, const gss_OID oid2)
{

        if (oid1 == oid2)
                return (1);
        if (!oid1 || !oid2)
                return (0);
        if (oid1->length != oid2->length)
                return (0);
        if (memcmp(oid1->elements, oid2->elements, oid1->length))
                return (0);
        return (1);
}

void
kgss_install_mech(gss_OID mech_type, const char *name, struct kobj_class *cls)
{
        struct kgss_mech *km;

        km = malloc(sizeof(struct kgss_mech), M_GSSAPI, M_WAITOK);
        km->km_mech_type = mech_type;
        km->km_mech_name = name;
        km->km_class = cls;
        LIST_INSERT_HEAD(&kgss_mechs, km, km_link);
}

void
kgss_uninstall_mech(gss_OID mech_type)
{
        struct kgss_mech *km;

        LIST_FOREACH(km, &kgss_mechs, km_link) {
                if (kgss_oid_equal(km->km_mech_type, mech_type)) {
                        LIST_REMOVE(km, km_link);
                        free(km, M_GSSAPI);
                        return;
                }
        }
}

gss_OID
kgss_find_mech_by_name(const char *name)
{
        struct kgss_mech *km;

        LIST_FOREACH(km, &kgss_mechs, km_link) {
                if (!strcmp(km->km_mech_name, name)) {
                        return (km->km_mech_type);
                }
        }
        return (GSS_C_NO_OID);
}

const char *
kgss_find_mech_by_oid(const gss_OID oid)
{
        struct kgss_mech *km;

        LIST_FOREACH(km, &kgss_mechs, km_link) {
                if (kgss_oid_equal(km->km_mech_type, oid)) {
                        return (km->km_mech_name);
                }
        }
        return (NULL);
}

gss_ctx_id_t
kgss_create_context(gss_OID mech_type)
{
        struct kgss_mech *km;
        gss_ctx_id_t ctx;

        LIST_FOREACH(km, &kgss_mechs, km_link) {
                if (kgss_oid_equal(km->km_mech_type, mech_type))
                        break;
        }
        if (!km)
                return (NULL);

        ctx = (gss_ctx_id_t) kobj_create(km->km_class, M_GSSAPI, M_WAITOK);
        KGSS_INIT(ctx);

        return (ctx);
}

void
kgss_delete_context(gss_ctx_id_t ctx, gss_buffer_t output_token)
{

        KGSS_DELETE(ctx, output_token);
        kobj_delete((kobj_t) ctx, M_GSSAPI);
}

OM_uint32
kgss_transfer_context(gss_ctx_id_t ctx, void *lctx)
{
        struct export_sec_context_res res;
        struct export_sec_context_args args;
        enum clnt_stat stat;
        OM_uint32 maj_stat;

        if (lctx != NULL) {
                maj_stat = KGSS_IMPORT(ctx, MIT_V1, lctx);
                ctx->handle = 0;
                return (maj_stat);
        }

        KGSS_CURVNET_SET_QUIET(KGSS_TD_TO_VNET(curthread));
        if (!KGSS_VNET(kgss_gssd_handle)) {
                KGSS_CURVNET_RESTORE();
                return (GSS_S_FAILURE);
        }

        args.ctx = ctx->handle;
        bzero(&res, sizeof(res));
        stat = gssd_export_sec_context_1(&args, &res, KGSS_VNET(kgss_gssd_handle));
        KGSS_CURVNET_RESTORE();
        if (stat != RPC_SUCCESS) {
                return (GSS_S_FAILURE);
        }

        maj_stat = KGSS_IMPORT(ctx, res.format, &res.interprocess_token);
        ctx->handle = 0;

        xdr_free((xdrproc_t) xdr_export_sec_context_res, &res);

        return (maj_stat);
}

void
kgss_copy_buffer(const gss_buffer_t from, gss_buffer_t to)
{
        to->length = from->length;
        if (from->length) {
                to->value = malloc(from->length, M_GSSAPI, M_WAITOK);
                bcopy(from->value, to->value, from->length);
        } else {
                to->value = NULL;
        }
}

/*
 * Acquire the kgss_gssd_handle and return it with a reference count,
 * if it is available.
 */
CLIENT *
kgss_gssd_client(void)
{
        CLIENT *cl;

        KGSS_CURVNET_SET_QUIET(KGSS_TD_TO_VNET(curthread));
        mtx_lock(&kgss_gssd_lock);
        cl = KGSS_VNET(kgss_gssd_handle);
        if (cl != NULL)
                CLNT_ACQUIRE(cl);
        mtx_unlock(&kgss_gssd_lock);
        KGSS_CURVNET_RESTORE();
        return (cl);
}

/*
 * Kernel module glue
 */
static int
kgssapi_modevent(module_t mod, int type, void *data)
{
        int error = 0;

        switch (type) {
        case MOD_LOAD:
                rpc_gss_entries.rpc_gss_refresh_auth = rpc_gss_refresh_auth;
                rpc_gss_entries.rpc_gss_secfind = rpc_gss_secfind;
                rpc_gss_entries.rpc_gss_secpurge = rpc_gss_secpurge;
                rpc_gss_entries.rpc_gss_seccreate = rpc_gss_seccreate;
                rpc_gss_entries.rpc_gss_set_defaults = rpc_gss_set_defaults;
                rpc_gss_entries.rpc_gss_max_data_length =
                    rpc_gss_max_data_length;
                rpc_gss_entries.rpc_gss_get_error = rpc_gss_get_error;
                rpc_gss_entries.rpc_gss_mech_to_oid = rpc_gss_mech_to_oid;
                rpc_gss_entries.rpc_gss_oid_to_mech = rpc_gss_oid_to_mech;
                rpc_gss_entries.rpc_gss_qop_to_num = rpc_gss_qop_to_num;
                rpc_gss_entries.rpc_gss_get_mechanisms = rpc_gss_get_mechanisms;
                rpc_gss_entries.rpc_gss_get_versions = rpc_gss_get_versions;
                rpc_gss_entries.rpc_gss_is_installed = rpc_gss_is_installed;
                rpc_gss_entries.rpc_gss_set_svc_name = rpc_gss_set_svc_name;
                rpc_gss_entries.rpc_gss_clear_svc_name = rpc_gss_clear_svc_name;
                rpc_gss_entries.rpc_gss_getcred = rpc_gss_getcred;
                rpc_gss_entries.rpc_gss_set_callback = rpc_gss_set_callback;
                rpc_gss_entries.rpc_gss_clear_callback = rpc_gss_clear_callback;
                rpc_gss_entries.rpc_gss_get_principal_name =
                    rpc_gss_get_principal_name;
                rpc_gss_entries.rpc_gss_svc_max_data_length =
                    rpc_gss_svc_max_data_length;
                rpc_gss_entries.rpc_gss_ip_to_srv_principal =
                    rpc_gss_ip_to_srv_principal;
                mtx_init(&kgss_gssd_lock, "kgss_gssd_lock", NULL, MTX_DEF);
                error = kgss_load();
                break;
        case MOD_UNLOAD:
#if 0
                kgss_unload();
                mtx_destroy(&kgss_gssd_lock);
#endif
                /*
                 * Unloading of the kgssapi module is not currently supported.
                 * If somebody wants this, we would need to keep track of
                 * currently executing threads and make sure the count is 0.
                 */
                /* FALLTHROUGH */
        default:
                error = EOPNOTSUPP;
        }
        return (error);
}
static moduledata_t kgssapi_mod = {
        "kgssapi",
        kgssapi_modevent,
        NULL,
};
DECLARE_MODULE(kgssapi, kgssapi_mod, SI_SUB_VFS, SI_ORDER_SECOND);
MODULE_DEPEND(kgssapi, xdr, 1, 1, 1);
MODULE_DEPEND(kgssapi, krpc, 1, 1, 1);
MODULE_VERSION(kgssapi, 1);