Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1111 insertions, 0 deletions

diff --git a/net/can/gw.c b/net/can/gw.c
new file mode 100644
index 000000000..9c2066323
--- /dev/null
+++ b/net/can/gw.c
@@ -0,0 +1,1111 @@
+/*
+ * gw.c - CAN frame Gateway/Router/Bridge with netlink interface
+ *
+ * Copyright (c) 2017 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_VERSION "20170425"
+#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 can_frame and;
+		struct can_frame or;
+		struct can_frame xor;
+		struct can_frame set;
+	} modframe;
+	struct {
+		u8 and;
+		u8 or;
+		u8 xor;
+		u8 set;
+	} modtype;
+	void (*modfunc[MAX_MODFUNCTIONS])(struct can_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 can_frame *cf, struct cgw_csum_xor *xor);
+		void (*crc8)(struct can_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 can_frame *cf, \
+					   struct cf_mod *mod) { op ; }
+
+MODFUNC(mod_and_id, cf->can_id &= mod->modframe.and.can_id)
+MODFUNC(mod_and_dlc, cf->can_dlc &= mod->modframe.and.can_dlc)
+MODFUNC(mod_and_data, *(u64 *)cf->data &= *(u64 *)mod->modframe.and.data)
+MODFUNC(mod_or_id, cf->can_id |= mod->modframe.or.can_id)
+MODFUNC(mod_or_dlc, cf->can_dlc |= mod->modframe.or.can_dlc)
+MODFUNC(mod_or_data, *(u64 *)cf->data |= *(u64 *)mod->modframe.or.data)
+MODFUNC(mod_xor_id, cf->can_id ^= mod->modframe.xor.can_id)
+MODFUNC(mod_xor_dlc, cf->can_dlc ^= mod->modframe.xor.can_dlc)
+MODFUNC(mod_xor_data, *(u64 *)cf->data ^= *(u64 *)mod->modframe.xor.data)
+MODFUNC(mod_set_id, cf->can_id = mod->modframe.set.can_id)
+MODFUNC(mod_set_dlc, cf->can_dlc = mod->modframe.set.can_dlc)
+MODFUNC(mod_set_data, *(u64 *)cf->data = *(u64 *)mod->modframe.set.data)
+
+static inline void canframecpy(struct can_frame *dst, struct can_frame *src)
+{
+	/*
+	 * Copy the struct members separately to ensure that no uninitialized
+	 * data are copied in the 3 bytes hole of the struct. This is needed
+	 * to make easy compares of the data in the struct cf_mod.
+	 */
+
+	dst->can_id = src->can_id;
+	dst->can_dlc = src->can_dlc;
+	*(u64 *)dst->data = *(u64 *)src->data;
+}
+
+static int cgw_chk_csum_parms(s8 fr, s8 to, s8 re)
+{
+	/*
+	 * absolute dlc values 0 .. 7 => 0 .. 7, e.g. data [0]
+	 * relative to received dlc -1 .. -8 :
+	 * e.g. for received dlc = 8
+	 * -1 => index = 7 (data[7])
+	 * -3 => index = 5 (data[5])
+	 * -8 => index = 0 (data[0])
+	 */
+
+	if (fr > -9 && fr < 8 &&
+	    to > -9 && to < 8 &&
+	    re > -9 && re < 8)
+		return 0;
+	else
+		return -EINVAL;
+}
+
+static inline int calc_idx(int idx, int rx_dlc)
+{
+	if (idx < 0)
+		return rx_dlc + idx;
+	else
+		return idx;
+}
+
+static void cgw_csum_xor_rel(struct can_frame *cf, struct cgw_csum_xor *xor)
+{
+	int from = calc_idx(xor->from_idx, cf->can_dlc);
+	int to = calc_idx(xor->to_idx, cf->can_dlc);
+	int res = calc_idx(xor->result_idx, cf->can_dlc);
+	u8 val = xor->init_xor_val;
+	int i;
+
+	if (from < 0 || to < 0 || res < 0)
+		return;
+
+	if (from <= to) {
+		for (i = from; i <= to; i++)
+			val ^= cf->data[i];
+	} else {
+		for (i = from; i >= to; i--)
+			val ^= cf->data[i];
+	}
+
+	cf->data[res] = val;
+}
+
+static void cgw_csum_xor_pos(struct can_frame *cf, struct cgw_csum_xor *xor)
+{
+	u8 val = xor->init_xor_val;
+	int i;
+
+	for (i = xor->from_idx; i <= xor->to_idx; i++)
+		val ^= cf->data[i];
+
+	cf->data[xor->result_idx] = val;
+}
+
+static void cgw_csum_xor_neg(struct can_frame *cf, struct cgw_csum_xor *xor)
+{
+	u8 val = xor->init_xor_val;
+	int i;
+
+	for (i = xor->from_idx; i >= xor->to_idx; i--)
+		val ^= cf->data[i];
+
+	cf->data[xor->result_idx] = val;
+}
+
+static void cgw_csum_crc8_rel(struct can_frame *cf, struct cgw_csum_crc8 *crc8)
+{
+	int from = calc_idx(crc8->from_idx, cf->can_dlc);
+	int to = calc_idx(crc8->to_idx, cf->can_dlc);
+	int res = calc_idx(crc8->result_idx, cf->can_dlc);
+	u8 crc = crc8->init_crc_val;
+	int i;
+
+	if (from < 0 || to < 0 || res < 0)
+		return;
+
+	if (from <= to) {
+		for (i = crc8->from_idx; i <= crc8->to_idx; i++)
+			crc = crc8->crctab[crc^cf->data[i]];
+	} else {
+		for (i = crc8->from_idx; i >= crc8->to_idx; i--)
+			crc = crc8->crctab[crc^cf->data[i]];
+	}
+
+	switch (crc8->profile) {
+
+	case CGW_CRC8PRF_1U8:
+		crc = crc8->crctab[crc^crc8->profile_data[0]];
+		break;
+
+	case  CGW_CRC8PRF_16U8:
+		crc = crc8->crctab[crc^crc8->profile_data[cf->data[1] & 0xF]];
+		break;
+
+	case CGW_CRC8PRF_SFFID_XOR:
+		crc = crc8->crctab[crc^(cf->can_id & 0xFF)^
+				   (cf->can_id >> 8 & 0xFF)];
+		break;
+
+	}
+
+	cf->data[crc8->result_idx] = crc^crc8->final_xor_val;
+}
+
+static void cgw_csum_crc8_pos(struct can_frame *cf, struct cgw_csum_crc8 *crc8)
+{
+	u8 crc = crc8->init_crc_val;
+	int i;
+
+	for (i = crc8->from_idx; i <= crc8->to_idx; i++)
+		crc = crc8->crctab[crc^cf->data[i]];
+
+	switch (crc8->profile) {
+
+	case CGW_CRC8PRF_1U8:
+		crc = crc8->crctab[crc^crc8->profile_data[0]];
+		break;
+
+	case  CGW_CRC8PRF_16U8:
+		crc = crc8->crctab[crc^crc8->profile_data[cf->data[1] & 0xF]];
+		break;
+
+	case CGW_CRC8PRF_SFFID_XOR:
+		crc = crc8->crctab[crc^(cf->can_id & 0xFF)^
+				   (cf->can_id >> 8 & 0xFF)];
+		break;
+	}
+
+	cf->data[crc8->result_idx] = crc^crc8->final_xor_val;
+}
+
+static void cgw_csum_crc8_neg(struct can_frame *cf, struct cgw_csum_crc8 *crc8)
+{
+	u8 crc = crc8->init_crc_val;
+	int i;
+
+	for (i = crc8->from_idx; i >= crc8->to_idx; i--)
+		crc = crc8->crctab[crc^cf->data[i]];
+
+	switch (crc8->profile) {
+
+	case CGW_CRC8PRF_1U8:
+		crc = crc8->crctab[crc^crc8->profile_data[0]];
+		break;
+
+	case  CGW_CRC8PRF_16U8:
+		crc = crc8->crctab[crc^crc8->profile_data[cf->data[1] & 0xF]];
+		break;
+
+	case CGW_CRC8PRF_SFFID_XOR:
+		crc = crc8->crctab[crc^(cf->can_id & 0xFF)^
+				   (cf->can_id >> 8 & 0xFF)];
+		break;
+	}
+
+	cf->data[crc8->result_idx] = crc^crc8->final_xor_val;
+}
+
+/* the receive & process & send function */
+static void can_can_gw_rcv(struct sk_buff *skb, void *data)
+{
+	struct cgw_job *gwj = (struct cgw_job *)data;
+	struct can_frame *cf;
+	struct sk_buff *nskb;
+	int modidx = 0;
+
+	/*
+	 * Do not handle CAN frames routed more than 'max_hops' times.
+	 * In general we should never catch this delimiter which is intended
+	 * to cover a misconfiguration protection (e.g. circular CAN routes).
+	 *
+	 * The Controller Area Network controllers only accept CAN frames with
+	 * correct CRCs - which are not visible in the controller registers.
+	 * According to skbuff.h documentation the csum_start element for IP
+	 * checksums is undefined/unused when ip_summed == CHECKSUM_UNNECESSARY.
+	 * Only CAN skbs can be processed here which already have this property.
+	 */
+
+#define cgw_hops(skb) ((skb)->csum_start)
+
+	BUG_ON(skb->ip_summed != CHECKSUM_UNNECESSARY);
+
+	if (cgw_hops(skb) >= max_hops) {
+		/* indicate deleted frames due to misconfiguration */
+		gwj->deleted_frames++;
+		return;
+	}
+
+	if (!(gwj->dst.dev->flags & IFF_UP)) {
+		gwj->dropped_frames++;
+		return;
+	}
+
+	/* is sending the skb back to the incoming interface not allowed? */
+	if (!(gwj->flags & CGW_FLAGS_CAN_IIF_TX_OK) &&
+	    can_skb_prv(skb)->ifindex == gwj->dst.dev->ifindex)
+		return;
+
+	/*
+	 * clone the given skb, which has not been done in can_rcv()
+	 *
+	 * When there is at least one modification function activated,
+	 * we need to copy the skb as we want to modify skb->data.
+	 */
+	if (gwj->mod.modfunc[0])
+		nskb = skb_copy(skb, GFP_ATOMIC);
+	else
+		nskb = skb_clone(skb, GFP_ATOMIC);
+
+	if (!nskb) {
+		gwj->dropped_frames++;
+		return;
+	}
+
+	/* put the incremented hop counter in the cloned skb */
+	cgw_hops(nskb) = cgw_hops(skb) + 1;
+
+	/* first processing of this CAN frame -> adjust to private hop limit */
+	if (gwj->limit_hops && cgw_hops(nskb) == 1)
+		cgw_hops(nskb) = max_hops - gwj->limit_hops + 1;
+
+	nskb->dev = gwj->dst.dev;
+
+	/* pointer to modifiable CAN frame */
+	cf = (struct can_frame *)nskb->data;
+
+	/* perform preprocessed modification functions if there are any */
+	while (modidx < MAX_MODFUNCTIONS && gwj->mod.modfunc[modidx])
+		(*gwj->mod.modfunc[modidx++])(cf, &gwj->mod);
+
+	/* Has the CAN frame been modified? */
+	if (modidx) {
+		/* get available space for the processed CAN frame type */
+		int max_len = nskb->len - offsetof(struct can_frame, data);
+
+		/* dlc may have changed, make sure it fits to the CAN frame */
+		if (cf->can_dlc > max_len)
+			goto out_delete;
+
+		/* check for checksum updates in classic CAN length only */
+		if (gwj->mod.csumfunc.crc8) {
+			if (cf->can_dlc > 8)
+				goto out_delete;
+
+			(*gwj->mod.csumfunc.crc8)(cf, &gwj->mod.csum.crc8);
+		}
+
+		if (gwj->mod.csumfunc.xor) {
+			if (cf->can_dlc > 8)
+				goto out_delete;
+
+			(*gwj->mod.csumfunc.xor)(cf, &gwj->mod.csum.xor);
+		}
+	}
+
+	/* clear the skb timestamp if not configured the other way */
+	if (!(gwj->flags & CGW_FLAGS_CAN_SRC_TSTAMP))
+		nskb->tstamp = 0;
+
+	/* send to netdevice */
+	if (can_send(nskb, gwj->flags & CGW_FLAGS_CAN_ECHO))
+		gwj->dropped_frames++;
+	else
+		gwj->handled_frames++;
+
+	return;
+
+ out_delete:
+	/* delete frame due to misconfiguration */
+	gwj->deleted_frames++;
+	kfree_skb(nskb);
+	return;
+}
+
+static inline int cgw_register_filter(struct net *net, struct cgw_job *gwj)
+{
+	return can_rx_register(net, gwj->src.dev, gwj->ccgw.filter.can_id,
+			       gwj->ccgw.filter.can_mask, can_can_gw_rcv,
+			       gwj, "gw", NULL);
+}
+
+static inline void cgw_unregister_filter(struct net *net, struct cgw_job *gwj)
+{
+	can_rx_unregister(net, gwj->src.dev, gwj->ccgw.filter.can_id,
+			  gwj->ccgw.filter.can_mask, can_can_gw_rcv, gwj);
+}
+
+static int cgw_notifier(struct notifier_block *nb,
+			unsigned long msg, void *ptr)
+{
+	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
+	struct net *net = dev_net(dev);
+
+	if (dev->type != ARPHRD_CAN)
+		return NOTIFY_DONE;
+
+	if (msg == NETDEV_UNREGISTER) {
+
+		struct cgw_job *gwj = NULL;
+		struct hlist_node *nx;
+
+		ASSERT_RTNL();
+
+		hlist_for_each_entry_safe(gwj, nx, &net->can.cgw_list, list) {
+
+			if (gwj->src.dev == dev || gwj->dst.dev == dev) {
+				hlist_del(&gwj->list);
+				cgw_unregister_filter(net, gwj);
+				synchronize_rcu();
+				kmem_cache_free(cgw_cache, gwj);
+			}
+		}
+	}
+
+	return NOTIFY_DONE;
+}
+
+static int cgw_put_job(struct sk_buff *skb, struct cgw_job *gwj, int type,
+		       u32 pid, u32 seq, int flags)
+{
+	struct cgw_frame_mod mb;
+	struct rtcanmsg *rtcan;
+	struct nlmsghdr *nlh;
+
+	nlh = nlmsg_put(skb, pid, seq, type, sizeof(*rtcan), flags);
+	if (!nlh)
+		return -EMSGSIZE;
+
+	rtcan = nlmsg_data(nlh);
+	rtcan->can_family = AF_CAN;
+	rtcan->gwtype = gwj->gwtype;
+	rtcan->flags = gwj->flags;
+
+	/* add statistics if available */
+
+	if (gwj->handled_frames) {
+		if (nla_put_u32(skb, CGW_HANDLED, gwj->handled_frames) < 0)
+			goto cancel;
+	}
+
+	if (gwj->dropped_frames) {
+		if (nla_put_u32(skb, CGW_DROPPED, gwj->dropped_frames) < 0)
+			goto cancel;
+	}
+
+	if (gwj->deleted_frames) {
+		if (nla_put_u32(skb, CGW_DELETED, gwj->deleted_frames) < 0)
+			goto cancel;
+	}
+
+	/* check non default settings of attributes */
+
+	if (gwj->limit_hops) {
+		if (nla_put_u8(skb, CGW_LIM_HOPS, gwj->limit_hops) < 0)
+			goto cancel;
+	}
+
+	if (gwj->mod.modtype.and) {
+		memcpy(&mb.cf, &gwj->mod.modframe.and, sizeof(mb.cf));
+		mb.modtype = gwj->mod.modtype.and;
+		if (nla_put(skb, CGW_MOD_AND, sizeof(mb), &mb) < 0)
+			goto cancel;
+	}
+
+	if (gwj->mod.modtype.or) {
+		memcpy(&mb.cf, &gwj->mod.modframe.or, sizeof(mb.cf));
+		mb.modtype = gwj->mod.modtype.or;
+		if (nla_put(skb, CGW_MOD_OR, sizeof(mb), &mb) < 0)
+			goto cancel;
+	}
+
+	if (gwj->mod.modtype.xor) {
+		memcpy(&mb.cf, &gwj->mod.modframe.xor, sizeof(mb.cf));
+		mb.modtype = gwj->mod.modtype.xor;
+		if (nla_put(skb, CGW_MOD_XOR, sizeof(mb), &mb) < 0)
+			goto cancel;
+	}
+
+	if (gwj->mod.modtype.set) {
+		memcpy(&mb.cf, &gwj->mod.modframe.set, sizeof(mb.cf));
+		mb.modtype = gwj->mod.modtype.set;
+		if (nla_put(skb, CGW_MOD_SET, sizeof(mb), &mb) < 0)
+			goto cancel;
+	}
+
+	if (gwj->mod.uid) {
+		if (nla_put_u32(skb, CGW_MOD_UID, gwj->mod.uid) < 0)
+			goto cancel;
+	}
+
+	if (gwj->mod.csumfunc.crc8) {
+		if (nla_put(skb, CGW_CS_CRC8, CGW_CS_CRC8_LEN,
+			    &gwj->mod.csum.crc8) < 0)
+			goto cancel;
+	}
+
+	if (gwj->mod.csumfunc.xor) {
+		if (nla_put(skb, CGW_CS_XOR, CGW_CS_XOR_LEN,
+			    &gwj->mod.csum.xor) < 0)
+			goto cancel;
+	}
+
+	if (gwj->gwtype == CGW_TYPE_CAN_CAN) {
+
+		if (gwj->ccgw.filter.can_id || gwj->ccgw.filter.can_mask) {
+			if (nla_put(skb, CGW_FILTER, sizeof(struct can_filter),
+				    &gwj->ccgw.filter) < 0)
+				goto cancel;
+		}
+
+		if (nla_put_u32(skb, CGW_SRC_IF, gwj->ccgw.src_idx) < 0)
+			goto cancel;
+
+		if (nla_put_u32(skb, CGW_DST_IF, gwj->ccgw.dst_idx) < 0)
+			goto cancel;
+	}
+
+	nlmsg_end(skb, nlh);
+	return 0;
+
+cancel:
+	nlmsg_cancel(skb, nlh);
+	return -EMSGSIZE;
+}
+
+/* Dump information about all CAN gateway jobs, in response to RTM_GETROUTE */
+static int cgw_dump_jobs(struct sk_buff *skb, struct netlink_callback *cb)
+{
+	struct net *net = sock_net(skb->sk);
+	struct cgw_job *gwj = NULL;
+	int idx = 0;
+	int s_idx = cb->args[0];
+
+	rcu_read_lock();
+	hlist_for_each_entry_rcu(gwj, &net->can.cgw_list, list) {
+		if (idx < s_idx)
+			goto cont;
+
+		if (cgw_put_job(skb, gwj, RTM_NEWROUTE, NETLINK_CB(cb->skb).portid,
+		    cb->nlh->nlmsg_seq, NLM_F_MULTI) < 0)
+			break;
+cont:
+		idx++;
+	}
+	rcu_read_unlock();
+
+	cb->args[0] = idx;
+
+	return skb->len;
+}
+
+static const struct nla_policy cgw_policy[CGW_MAX+1] = {
+	[CGW_MOD_AND]	= { .len = sizeof(struct cgw_frame_mod) },
+	[CGW_MOD_OR]	= { .len = sizeof(struct cgw_frame_mod) },
+	[CGW_MOD_XOR]	= { .len = sizeof(struct cgw_frame_mod) },
+	[CGW_MOD_SET]	= { .len = sizeof(struct cgw_frame_mod) },
+	[CGW_CS_XOR]	= { .len = sizeof(struct cgw_csum_xor) },
+	[CGW_CS_CRC8]	= { .len = sizeof(struct cgw_csum_crc8) },
+	[CGW_SRC_IF]	= { .type = NLA_U32 },
+	[CGW_DST_IF]	= { .type = NLA_U32 },
+	[CGW_FILTER]	= { .len = sizeof(struct can_filter) },
+	[CGW_LIM_HOPS]	= { .type = NLA_U8 },
+	[CGW_MOD_UID]	= { .type = NLA_U32 },
+};
+
+/* check for common and gwtype specific attributes */
+static int cgw_parse_attr(struct nlmsghdr *nlh, struct cf_mod *mod,
+			  u8 gwtype, void *gwtypeattr, u8 *limhops)
+{
+	struct nlattr *tb[CGW_MAX+1];
+	struct cgw_frame_mod mb;
+	int modidx = 0;
+	int err = 0;
+
+	/* initialize modification & checksum data space */
+	memset(mod, 0, sizeof(*mod));
+
+	err = nlmsg_parse(nlh, sizeof(struct rtcanmsg), tb, CGW_MAX,
+			  cgw_policy, NULL);
+	if (err < 0)
+		return err;
+
+	if (tb[CGW_LIM_HOPS]) {
+		*limhops = nla_get_u8(tb[CGW_LIM_HOPS]);
+
+		if (*limhops < 1 || *limhops > max_hops)
+			return -EINVAL;
+	}
+
+	/* check for AND/OR/XOR/SET modifications */
+
+	if (tb[CGW_MOD_AND]) {
+		nla_memcpy(&mb, tb[CGW_MOD_AND], CGW_MODATTR_LEN);
+
+		canframecpy(&mod->modframe.and, &mb.cf);
+		mod->modtype.and = mb.modtype;
+
+		if (mb.modtype & CGW_MOD_ID)
+			mod->modfunc[modidx++] = mod_and_id;
+
+		if (mb.modtype & CGW_MOD_DLC)
+			mod->modfunc[modidx++] = mod_and_dlc;
+
+		if (mb.modtype & CGW_MOD_DATA)
+			mod->modfunc[modidx++] = mod_and_data;
+	}
+
+	if (tb[CGW_MOD_OR]) {
+		nla_memcpy(&mb, tb[CGW_MOD_OR], CGW_MODATTR_LEN);
+
+		canframecpy(&mod->modframe.or, &mb.cf);
+		mod->modtype.or = mb.modtype;
+
+		if (mb.modtype & CGW_MOD_ID)
+			mod->modfunc[modidx++] = mod_or_id;
+
+		if (mb.modtype & CGW_MOD_DLC)
+			mod->modfunc[modidx++] = mod_or_dlc;
+
+		if (mb.modtype & CGW_MOD_DATA)
+			mod->modfunc[modidx++] = mod_or_data;
+	}
+
+	if (tb[CGW_MOD_XOR]) {
+		nla_memcpy(&mb, tb[CGW_MOD_XOR], CGW_MODATTR_LEN);
+
+		canframecpy(&mod->modframe.xor, &mb.cf);
+		mod->modtype.xor = mb.modtype;
+
+		if (mb.modtype & CGW_MOD_ID)
+			mod->modfunc[modidx++] = mod_xor_id;
+
+		if (mb.modtype & CGW_MOD_DLC)
+			mod->modfunc[modidx++] = mod_xor_dlc;
+
+		if (mb.modtype & CGW_MOD_DATA)
+			mod->modfunc[modidx++] = mod_xor_data;
+	}
+
+	if (tb[CGW_MOD_SET]) {
+		nla_memcpy(&mb, tb[CGW_MOD_SET], CGW_MODATTR_LEN);
+
+		canframecpy(&mod->modframe.set, &mb.cf);
+		mod->modtype.set = mb.modtype;
+
+		if (mb.modtype & CGW_MOD_ID)
+			mod->modfunc[modidx++] = mod_set_id;
+
+		if (mb.modtype & CGW_MOD_DLC)
+			mod->modfunc[modidx++] = mod_set_dlc;
+
+		if (mb.modtype & CGW_MOD_DATA)
+			mod->modfunc[modidx++] = mod_set_data;
+	}
+
+	/* check for checksum operations after CAN frame modifications */
+	if (modidx) {
+
+		if (tb[CGW_CS_CRC8]) {
+			struct cgw_csum_crc8 *c = nla_data(tb[CGW_CS_CRC8]);
+
+			err = cgw_chk_csum_parms(c->from_idx, c->to_idx,
+						 c->result_idx);
+			if (err)
+				return err;
+
+			nla_memcpy(&mod->csum.crc8, tb[CGW_CS_CRC8],
+				   CGW_CS_CRC8_LEN);
+
+			/*
+			 * select dedicated processing function to reduce
+			 * runtime operations in receive hot path.
+			 */
+			if (c->from_idx < 0 || c->to_idx < 0 ||
+			    c->result_idx < 0)
+				mod->csumfunc.crc8 = cgw_csum_crc8_rel;
+			else if (c->from_idx <= c->to_idx)
+				mod->csumfunc.crc8 = cgw_csum_crc8_pos;
+			else
+				mod->csumfunc.crc8 = cgw_csum_crc8_neg;
+		}
+
+		if (tb[CGW_CS_XOR]) {
+			struct cgw_csum_xor *c = nla_data(tb[CGW_CS_XOR]);
+
+			err = cgw_chk_csum_parms(c->from_idx, c->to_idx,
+						 c->result_idx);
+			if (err)
+				return err;
+
+			nla_memcpy(&mod->csum.xor, tb[CGW_CS_XOR],
+				   CGW_CS_XOR_LEN);
+
+			/*
+			 * select dedicated processing function to reduce
+			 * runtime operations in receive hot path.
+			 */
+			if (c->from_idx < 0 || c->to_idx < 0 ||
+			    c->result_idx < 0)
+				mod->csumfunc.xor = cgw_csum_xor_rel;
+			else if (c->from_idx <= c->to_idx)
+				mod->csumfunc.xor = cgw_csum_xor_pos;
+			else
+				mod->csumfunc.xor = cgw_csum_xor_neg;
+		}
+
+		if (tb[CGW_MOD_UID]) {
+			nla_memcpy(&mod->uid, tb[CGW_MOD_UID], sizeof(u32));
+		}
+	}
+
+	if (gwtype == CGW_TYPE_CAN_CAN) {
+
+		/* check CGW_TYPE_CAN_CAN specific attributes */
+
+		struct can_can_gw *ccgw = (struct can_can_gw *)gwtypeattr;
+		memset(ccgw, 0, sizeof(*ccgw));
+
+		/* check for can_filter in attributes */
+		if (tb[CGW_FILTER])
+			nla_memcpy(&ccgw->filter, tb[CGW_FILTER],
+				   sizeof(struct can_filter));
+
+		err = -ENODEV;
+
+		/* specifying two interfaces is mandatory */
+		if (!tb[CGW_SRC_IF] || !tb[CGW_DST_IF])
+			return err;
+
+		ccgw->src_idx = nla_get_u32(tb[CGW_SRC_IF]);
+		ccgw->dst_idx = nla_get_u32(tb[CGW_DST_IF]);
+
+		/* both indices set to 0 for flushing all routing entries */
+		if (!ccgw->src_idx && !ccgw->dst_idx)
+			return 0;
+
+		/* only one index set to 0 is an error */
+		if (!ccgw->src_idx || !ccgw->dst_idx)
+			return err;
+	}
+
+	/* add the checks for other gwtypes here */
+
+	return 0;
+}
+
+static int cgw_create_job(struct sk_buff *skb,  struct nlmsghdr *nlh,
+			  struct netlink_ext_ack *extack)
+{
+	struct net *net = sock_net(skb->sk);
+	struct rtcanmsg *r;
+	struct cgw_job *gwj;
+	struct cf_mod mod;
+	struct can_can_gw ccgw;
+	u8 limhops = 0;
+	int err = 0;
+
+	if (!netlink_capable(skb, CAP_NET_ADMIN))
+		return -EPERM;
+
+	if (nlmsg_len(nlh) < sizeof(*r))
+		return -EINVAL;
+
+	r = nlmsg_data(nlh);
+	if (r->can_family != AF_CAN)
+		return -EPFNOSUPPORT;
+
+	/* so far we only support CAN -> CAN routings */
+	if (r->gwtype != CGW_TYPE_CAN_CAN)
+		return -EINVAL;
+
+	err = cgw_parse_attr(nlh, &mod, CGW_TYPE_CAN_CAN, &ccgw, &limhops);
+	if (err < 0)
+		return err;
+
+	if (mod.uid) {
+
+		ASSERT_RTNL();
+
+		/* check for updating an existing job with identical uid */
+		hlist_for_each_entry(gwj, &net->can.cgw_list, list) {
+
+			if (gwj->mod.uid != mod.uid)
+				continue;
+
+			/* interfaces & filters must be identical */
+			if (memcmp(&gwj->ccgw, &ccgw, sizeof(ccgw)))
+				return -EINVAL;
+
+			/* update modifications with disabled softirq & quit */
+			local_bh_disable();
+			memcpy(&gwj->mod, &mod, sizeof(mod));
+			local_bh_enable();
+			return 0;
+		}
+	}
+
+	/* ifindex == 0 is not allowed for job creation */
+	if (!ccgw.src_idx || !ccgw.dst_idx)
+		return -ENODEV;
+
+	gwj = kmem_cache_alloc(cgw_cache, GFP_KERNEL);
+	if (!gwj)
+		return -ENOMEM;
+
+	gwj->handled_frames = 0;
+	gwj->dropped_frames = 0;
+	gwj->deleted_frames = 0;
+	gwj->flags = r->flags;
+	gwj->gwtype = r->gwtype;
+	gwj->limit_hops = limhops;
+
+	/* insert already parsed information */
+	memcpy(&gwj->mod, &mod, sizeof(mod));
+	memcpy(&gwj->ccgw, &ccgw, sizeof(ccgw));
+
+	err = -ENODEV;
+
+	gwj->src.dev = __dev_get_by_index(net, gwj->ccgw.src_idx);
+
+	if (!gwj->src.dev)
+		goto out;
+
+	if (gwj->src.dev->type != ARPHRD_CAN)
+		goto out;
+
+	gwj->dst.dev = __dev_get_by_index(net, gwj->ccgw.dst_idx);
+
+	if (!gwj->dst.dev)
+		goto out;
+
+	if (gwj->dst.dev->type != ARPHRD_CAN)
+		goto out;
+
+	ASSERT_RTNL();
+
+	err = cgw_register_filter(net, gwj);
+	if (!err)
+		hlist_add_head_rcu(&gwj->list, &net->can.cgw_list);
+out:
+	if (err)
+		kmem_cache_free(cgw_cache, gwj);
+
+	return err;
+}
+
+static void cgw_remove_all_jobs(struct net *net)
+{
+	struct cgw_job *gwj = NULL;
+	struct hlist_node *nx;
+
+	ASSERT_RTNL();
+
+	hlist_for_each_entry_safe(gwj, nx, &net->can.cgw_list, list) {
+		hlist_del(&gwj->list);
+		cgw_unregister_filter(net, gwj);
+		synchronize_rcu();
+		kmem_cache_free(cgw_cache, gwj);
+	}
+}
+
+static int cgw_remove_job(struct sk_buff *skb, struct nlmsghdr *nlh,
+			  struct netlink_ext_ack *extack)
+{
+	struct net *net = sock_net(skb->sk);
+	struct cgw_job *gwj = NULL;
+	struct hlist_node *nx;
+	struct rtcanmsg *r;
+	struct cf_mod mod;
+	struct can_can_gw ccgw;
+	u8 limhops = 0;
+	int err = 0;
+
+	if (!netlink_capable(skb, CAP_NET_ADMIN))
+		return -EPERM;
+
+	if (nlmsg_len(nlh) < sizeof(*r))
+		return -EINVAL;
+
+	r = nlmsg_data(nlh);
+	if (r->can_family != AF_CAN)
+		return -EPFNOSUPPORT;
+
+	/* so far we only support CAN -> CAN routings */
+	if (r->gwtype != CGW_TYPE_CAN_CAN)
+		return -EINVAL;
+
+	err = cgw_parse_attr(nlh, &mod, CGW_TYPE_CAN_CAN, &ccgw, &limhops);
+	if (err < 0)
+		return err;
+
+	/* two interface indices both set to 0 => remove all entries */
+	if (!ccgw.src_idx && !ccgw.dst_idx) {
+		cgw_remove_all_jobs(net);
+		return 0;
+	}
+
+	err = -EINVAL;
+
+	ASSERT_RTNL();
+
+	/* remove only the first matching entry */
+	hlist_for_each_entry_safe(gwj, nx, &net->can.cgw_list, list) {
+
+		if (gwj->flags != r->flags)
+			continue;
+
+		if (gwj->limit_hops != limhops)
+			continue;
+
+		/* we have a match when uid is enabled and identical */
+		if (gwj->mod.uid || mod.uid) {
+			if (gwj->mod.uid != mod.uid)
+				continue;
+		} else {
+			/* no uid => check for identical modifications */
+			if (memcmp(&gwj->mod, &mod, sizeof(mod)))
+				continue;
+		}
+
+		/* if (r->gwtype == CGW_TYPE_CAN_CAN) - is made sure here */
+		if (memcmp(&gwj->ccgw, &ccgw, sizeof(ccgw)))
+			continue;
+
+		hlist_del(&gwj->list);
+		cgw_unregister_filter(net, gwj);
+		synchronize_rcu();
+		kmem_cache_free(cgw_cache, gwj);
+		err = 0;
+		break;
+	}
+
+	return err;
+}
+
+static int __net_init cangw_pernet_init(struct net *net)
+{
+	INIT_HLIST_HEAD(&net->can.cgw_list);
+	return 0;
+}
+
+static void __net_exit cangw_pernet_exit(struct net *net)
+{
+	rtnl_lock();
+	cgw_remove_all_jobs(net);
+	rtnl_unlock();
+}
+
+static struct pernet_operations cangw_pernet_ops = {
+	.init = cangw_pernet_init,
+	.exit = cangw_pernet_exit,
+};
+
+static __init int cgw_module_init(void)
+{
+	int ret;
+
+	/* sanitize given module parameter */
+	max_hops = clamp_t(unsigned int, max_hops, CGW_MIN_HOPS, CGW_MAX_HOPS);
+
+	pr_info("can: netlink gateway (rev " CAN_GW_VERSION ") max_hops=%d\n",
+		max_hops);
+
+	ret = register_pernet_subsys(&cangw_pernet_ops);
+	if (ret)
+		return ret;
+
+	ret = -ENOMEM;
+	cgw_cache = kmem_cache_create("can_gw", sizeof(struct cgw_job),
+				      0, 0, NULL);
+	if (!cgw_cache)
+		goto out_cache_create;
+
+	/* set notifier */
+	notifier.notifier_call = cgw_notifier;
+	ret = register_netdevice_notifier(&notifier);
+	if (ret)
+		goto out_register_notifier;
+
+	ret = rtnl_register_module(THIS_MODULE, PF_CAN, RTM_GETROUTE,
+				   NULL, cgw_dump_jobs, 0);
+	if (ret)
+		goto out_rtnl_register1;
+
+	ret = rtnl_register_module(THIS_MODULE, PF_CAN, RTM_NEWROUTE,
+				   cgw_create_job, NULL, 0);
+	if (ret)
+		goto out_rtnl_register2;
+	ret = rtnl_register_module(THIS_MODULE, PF_CAN, RTM_DELROUTE,
+				   cgw_remove_job, NULL, 0);
+	if (ret)
+		goto out_rtnl_register3;
+
+	return 0;
+
+out_rtnl_register3:
+	rtnl_unregister(PF_CAN, RTM_NEWROUTE);
+out_rtnl_register2:
+	rtnl_unregister(PF_CAN, RTM_GETROUTE);
+out_rtnl_register1:
+	unregister_netdevice_notifier(&notifier);
+out_register_notifier:
+	kmem_cache_destroy(cgw_cache);
+out_cache_create:
+	unregister_pernet_subsys(&cangw_pernet_ops);
+
+	return ret;
+}
+
+static __exit void cgw_module_exit(void)
+{
+	rtnl_unregister_all(PF_CAN);
+
+	unregister_netdevice_notifier(&notifier);
+
+	unregister_pernet_subsys(&cangw_pernet_ops);
+	rcu_barrier(); /* Wait for completion of call_rcu()'s */
+
+	kmem_cache_destroy(cgw_cache);
+}
+
+module_init(cgw_module_init);
+module_exit(cgw_module_exit);