[PATCH] can: notifiers: remove CAN filters independent from namespace

[Oliver Hartkopp <socketcan@hartkopp.net>]

Remove the namespace equality check in the netdev notifiers for BCM,
ISOTP, and RAW sockets.

When the devices namespace is changed the socket namespace and the device
namespace might differ. The net_eq(dev_net(dev), sock_net(sk)) check
therefore skipped the removal of the CAN filters from the (ns changed)
CAN device.

Since the `struct net_device` pointer is globally unique, the notifier
should always process the unregister event and remove the CAN filters if
it matches the socket's bound device, regardless of the device's current
network namespace.

Change all can_rx_unregister() calling sites to use dev_net(dev) instead
of sock_net(sk) to retrieve the namespace (only missing in isotp.c).

Fixes: e057dd3fc20f ("can: add ISO 15765-2:2016 transport protocol")
Reported-by: Norbert Szetei <norbert@doyensec.com>
Link: https://lore.kernel.org/linux-can/CEA6A38A-2646-4ADA-95B4-CBAE2F301A8E@doyensec.com/
Cc: stable@vger.kernel.org
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
---
 net/can/bcm.c   | 3 ---
 net/can/isotp.c | 7 ++-----
 net/can/raw.c   | 3 ---
 3 files changed, 2 insertions(+), 11 deletions(-)

diff --git a/net/can/bcm.c b/net/can/bcm.c
index 3d637a1e0ac1..aaa5163c46cc 100644
--- a/net/can/bcm.c
+++ b/net/can/bcm.c
@@ -1792,13 +1792,10 @@ static void bcm_notify(struct bcm_sock *bo, unsigned long msg,
 {
 	struct sock *sk = &bo->sk;
 	struct bcm_op *op;
 	int notify_enodev = 0;
 
-	if (!net_eq(dev_net(dev), sock_net(sk)))
-		return;
-
 	switch (msg) {
 
 	case NETDEV_UNREGISTER:
 		lock_sock(sk);
 
diff --git a/net/can/isotp.c b/net/can/isotp.c
index 155530aedce2..0835a4758a72 100644
--- a/net/can/isotp.c
+++ b/net/can/isotp.c
@@ -1490,15 +1490,15 @@ static int isotp_release(struct socket *sock)
 	/* remove current filters & unregister
 	 * tracked reference so->dev is taken at bind() time with rtnl_lock
 	 */
 	if (so->bound && so->dev) {
 		if (isotp_register_rxid(so))
-			can_rx_unregister(net, so->dev, so->rxid,
+			can_rx_unregister(dev_net(so->dev), so->dev, so->rxid,
 					  SINGLE_MASK(so->rxid),
 					  isotp_rcv, sk);
 
-		can_rx_unregister(net, so->dev, so->txid,
+		can_rx_unregister(dev_net(so->dev), so->dev, so->txid,
 				  SINGLE_MASK(so->txid),
 				  isotp_rcv_echo, sk);
 		netdev_put(so->dev, &so->dev_tracker);
 	}
 
@@ -1846,13 +1846,10 @@ static int isotp_getsockopt(struct socket *sock, int level, int optname,
 static void isotp_notify(struct isotp_sock *so, unsigned long msg,
 			 struct net_device *dev)
 {
 	struct sock *sk = &so->sk;
 
-	if (!net_eq(dev_net(dev), sock_net(sk)))
-		return;
-
 	if (so->dev != dev)
 		return;
 
 	switch (msg) {
 	case NETDEV_UNREGISTER:
diff --git a/net/can/raw.c b/net/can/raw.c
index 82d9c0499c95..c5596fc9aac5 100644
--- a/net/can/raw.c
+++ b/net/can/raw.c
@@ -300,13 +300,10 @@ static int raw_enable_allfilters(struct net *net, struct net_device *dev,
 static void raw_notify(struct raw_sock *ro, unsigned long msg,
 		       struct net_device *dev)
 {
 	struct sock *sk = &ro->sk;
 
-	if (!net_eq(dev_net(dev), sock_net(sk)))
-		return;
-
 	if (ro->dev != dev)
 		return;
 
 	switch (msg) {
 	case NETDEV_UNREGISTER:
-- 
2.53.0