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: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
diff --git a/net/can/raw.c b/net/can/raw.c
index 63ffdb0..0c8d537 100644
--- a/net/can/raw.c
+++ b/net/can/raw.c
@@ -74,6 +74,11 @@
* 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 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 @@
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 @@
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 @@
ro->ifindex = 0;
ro->bound = 0;
ro->count = 0;
+ free_percpu(ro->uniq);
sock_orphan(sk);
sock->sk = NULL;