path: root/net/rxrpc/rxkad.c

// SPDX-License-Identifier: GPL-2.0-or-later
/* Kerberos-based RxRPC security
 *
 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <crypto/skcipher.h>
#include <linux/module.h>
#include <linux/net.h>
#include <linux/skbuff.h>
#include <linux/udp.h>
#include <linux/scatterlist.h>
#include <linux/ctype.h>
#include <linux/slab.h>
#include <linux/key-type.h>
#include <net/sock.h>
#include <net/af_rxrpc.h>
#include <keys/rxrpc-type.h>
#include "ar-internal.h"

#define RXKAD_VERSION			2
#define MAXKRB5TICKETLEN		1024
#define RXKAD_TKT_TYPE_KERBEROS_V5	256
#define ANAME_SZ			40	/* size of authentication name */
#define INST_SZ				40	/* size of principal's instance */
#define REALM_SZ			40	/* size of principal's auth domain */
#define SNAME_SZ			40	/* size of service name */
#define RXKAD_ALIGN			8

struct rxkad_level1_hdr {
	__be32	data_size;	/* true data size (excluding padding) */
};

struct rxkad_level2_hdr {
	__be32	data_size;	/* true data size (excluding padding) */
	__be32	checksum;	/* decrypted data checksum */
};

static int rxkad_prime_packet_security(struct rxrpc_connection *conn,
				       struct crypto_sync_skcipher *ci);

/*
 * this holds a pinned cipher so that keventd doesn't get called by the cipher
 * alloc routine, but since we have it to hand, we use it to decrypt RESPONSE
 * packets
 */
static struct crypto_sync_skcipher *rxkad_ci;
static struct skcipher_request *rxkad_ci_req;
static DEFINE_MUTEX(rxkad_ci_mutex);

/*
 * Parse the information from a server key
 *
 * The data should be the 8-byte secret key.
 */
static int rxkad_preparse_server_key(struct key_preparsed_payload *prep)
{
	struct crypto_skcipher *ci;

	if (prep->datalen != 8)
		return -EINVAL;

	memcpy(&prep->payload.data[2], prep->data, 8);

	ci = crypto_alloc_skcipher("pcbc(des)", 0, CRYPTO_ALG_ASYNC);
	if (IS_ERR(ci)) {
		_leave(" = %ld", PTR_ERR(ci));
		return PTR_ERR(ci);
	}

	if (crypto_skcipher_setkey(ci, prep->data, 8) < 0)
		BUG();

	prep->payload.data[0] = ci;
	_leave(" = 0");
	return 0;
}

static void rxkad_free_preparse_server_key(struct key_preparsed_payload *prep)
{

	if (prep->payload.data[0])
		crypto_free_skcipher(prep->payload.data[0]);
}

static void rxkad_destroy_server_key(struct key *key)
{
	if (key->payload.data[0]) {
		crypto_free_skcipher(key->payload.data[0]);
		key->payload.data[0] = NULL;
	}
}

/*
 * initialise connection security
 */
static int rxkad_init_connection_security(struct rxrpc_connection *conn,
					  struct rxrpc_key_token *token)
{
	struct