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Commit 514ac99c authored by Oliver Hartkopp's avatar Oliver Hartkopp Committed by Marc Kleine-Budde
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can: fix multiple delivery of a single CAN frame for overlapping CAN filters 



The CAN_RAW socket can set multiple CAN identifier specific filters that lead
to multiple filters in the af_can.c filter processing. These filters are
indenpendent from each other which leads to logical OR'ed filters when applied.

This patch makes sure that every CAN frame which is filtered for a specific
socket is only delivered once to the user space. This is independent from the
number of matching CAN filters of this socket.

As the raw_rcv() function is executed from NET_RX softirq the introduced
variables are implemented as per-CPU variables to avoid extensive locking at
CAN frame reception time.

Signed-off-by: default avatarOliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: default avatarMarc Kleine-Budde <mkl@pengutronix.de>
parent a0bc163a

net/can/raw.c

+21 −0
Original line number Diff line number Diff line
@@ -74,6 +74,11 @@ MODULE_ALIAS("can-proto-1"); 
 * storing the single filter in dfilter, to avoid using dynamic memory.

 */



struct uniqframe {

	ktime_t tstamp;

	const struct sk_buff *skb;

};



struct raw_sock {

	struct sock sk;

	int bound;
@@ -86,6 +91,7 @@ struct raw_sock { 
	struct can_filter dfilter; /* default/single filter */

	struct can_filter *filter; /* pointer to filter(s) */

	can_err_mask_t err_mask;

	struct uniqframe __percpu *uniq;

};



/*
@@ -123,6 +129,15 @@ static void raw_rcv(struct sk_buff *oskb, void *data) 
	if (!ro->fd_frames && oskb->len != CAN_MTU)

		return;



	/* eliminate multiple filter matches for the same skb */

	if (this_cpu_ptr(ro->uniq)->skb == oskb &&

	    ktime_equal(this_cpu_ptr(ro->uniq)->tstamp, oskb->tstamp)) {

		return;

	} else {

		this_cpu_ptr(ro->uniq)->skb = oskb;

		this_cpu_ptr(ro->uniq)->tstamp = oskb->tstamp;

	}



	/* clone the given skb to be able to enqueue it into the rcv queue */

	skb = skb_clone(oskb, GFP_ATOMIC);

	if (!skb)
@@ -297,6 +312,11 @@ static int raw_init(struct sock *sk) 
	ro->recv_own_msgs    = 0;

	ro->fd_frames        = 0;



	/* alloc_percpu provides zero'ed memory */

	ro->uniq = alloc_percpu(struct uniqframe);

	if (unlikely(!ro->uniq))

		return -ENOMEM;



	/* set notifier */

	ro->notifier.notifier_call = raw_notifier;
@@ -339,6 +359,7 @@ static int raw_release(struct socket *sock) 
	ro->ifindex = 0;

	ro->bound   = 0;

	ro->count   = 0;

	free_percpu(ro->uniq);



	sock_orphan(sk);

	sock->sk = NULL;