path: root/net/can/gw.c

// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
/* gw.c - CAN frame Gateway/Router/Bridge with netlink interface
 *
 * Copyright (c) 2019 Volkswagen Group Electronic Research
 * All rights reserved.
 *
 * 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.
 * 3. Neither the name of Volkswagen nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * Alternatively, provided that this notice is retained in full, this
 * software may be distributed under the terms of the GNU General
 * Public License ("GPL") version 2, in which case the provisions of the
 * GPL apply INSTEAD OF those given above.
 *
 * The provided data structures and external interfaces from this code
 * are not restricted to be used by modules with a GPL compatible license.
 *
 * 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
 * OWNER 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 <linux/module.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/rcupdate.h>
#include <linux/rculist.h>
#include <linux/net.h>
#include <linux/netdevice.h>
#include <linux/if_arp.h>
#include <linux/skbuff.h>
#include <linux/can.h>
#include <linux/can/core.h>
#include <linux/can/skb.h>
#include <linux/can/gw.h>
#include <net/rtnetlink.h>
#include <net/net_namespace.h>
#include <net/sock.h>

#define CAN_GW_NAME "can-gw"

MODULE_DESCRIPTION("PF_CAN netlink gateway");
MODULE_LICENSE("Dual BSD/GPL");
MODULE_AUTHOR("Oliver Hartkopp <oliver.hartkopp@volkswagen.de>");
MODULE_ALIAS(CAN_GW_NAME);

#define CGW_MIN_HOPS 1
#define CGW_MAX_HOPS 6
#define CGW_DEFAULT_HOPS 1

static unsigned int max_hops __read_mostly = CGW_DEFAULT_HOPS;
module_param(max_hops, uint, 0444);
MODULE_PARM_DESC(max_hops,
		 "maximum " CAN_GW_NAME " routing hops for CAN frames "
		 "(valid values: " __stringify(CGW_MIN_HOPS) "-"
		 __stringify(CGW_MAX_HOPS) " hops, "
		 "default: " __stringify(CGW_DEFAULT_HOPS) ")");

static struct notifier_block notifier;
static struct kmem_cache *cgw_cache __read_mostly;

/* structure that contains the (on-the-fly) CAN frame modifications */
struct cf_mod {
	struct {
		struct canfd_frame and;
		struct canfd_frame or;
		struct canfd_frame xor;
		struct canfd_frame set;
	} modframe;
	struct {
		u8 and;
		u8 or;
		u8 xor;
		u8 set;
	} modtype;
	void (*modfunc[MAX_MODFUNCTIONS])(struct canfd_frame *cf,
					  struct cf_mod *mod);

	/* CAN frame checksum calculation after CAN frame modifications */
	struct {
		struct cgw_csum_xor xor;
		struct cgw_csum_crc8 crc8;
	} csum;
	struct {
		void (*xor)(struct canfd_frame *cf,
			    struct cgw_csum_xor *xor);
		void (*crc8)(struct canfd_frame *cf,
			     struct cgw_csum_crc8 *crc8);
	} csumfunc;
	u32 uid;
};

/* So far we just support CAN -> CAN routing and frame modifications.
 *
 * The internal can_can_gw structure contains data and attributes for
 * a CAN -> CAN gateway job.
 */
struct can_can_gw {
	struct can_filter filter;
	int src_idx;
	int dst_idx;
};

/* list entry for CAN gateways jobs */
struct cgw_job {
	struct hlist_node list;
	struct rcu_head rcu;
	u32 handled_frames;
	u32 dropped_frames;
	u32 deleted_frames;
	struct cf_mod mod;
	union {
		/* CAN frame data source */
		struct net_device *dev;
	} src;
	union {
		/* CAN frame data destination */
		struct net_device *dev;
	} dst;
	union {
		struct can_can_gw ccgw;
		/* tbc */
	};
	u8 gwtype;
	u8 limit_hops;
	u16 flags;
};

/* modification functions that are invoked in the hot path in can_can_gw_rcv */

#define MODFUNC(func, op) static void func(struct canfd_frame *cf, \
					   struct cf_mod *mod) { op ; }