[PATCH net] vxlan: drop packets from invalid src-address

[PATCH net] vxlan: drop packets from invalid src-address

[David Bauer]

The VXLAN driver currently does not check if the inner layer2
source-address is valid.

In case source-address snooping/learning is enabled, a entry in the FDB
for the invalid address is created with the layer3 address of the tunnel
endpoint.

If the frame happens to have a non-unicast address set, all this
non-unicast traffic is subsequently not flooded to the tunnel network
but sent to the learnt host in the FDB. To make matters worse, this FDB
entry does not expire.

Apply the same filtering for packets as it is done for bridges. This not
only drops these invalid packets but avoids them from being learnt into
the FDB.

Fixes: d342894c5d2f ("vxlan: virtual extensible lan")

Suggested-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David Bauer <mail@david-bauer.net>
---
 drivers/net/vxlan/vxlan_core.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/vxlan/vxlan_core.c b/drivers/net/vxlan/vxlan_core.c
index 3495591a5c29..ba319fc21957 100644
--- a/drivers/net/vxlan/vxlan_core.c
+++ b/drivers/net/vxlan/vxlan_core.c
@@ -1615,6 +1615,10 @@ static bool vxlan_set_mac(struct vxlan_dev *vxlan,
 	if (ether_addr_equal(eth_hdr(skb)->h_source, vxlan->dev->dev_addr))
 		return false;
 
+	/* Ignore packets from invalid src-address */
+	if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
+		return false;
+
 	/* Get address from the outer IP header */
 	if (vxlan_get_sk_family(vs) == AF_INET) {
 		saddr.sin.sin_addr.s_addr = ip_hdr(skb)->saddr;
-- 
2.43.0

Re: [PATCH net] vxlan: drop packets from invalid src-address

[Ido Schimmel]

On Wed, Apr 10, 2024 at 03:09:17AM +0200, David Bauer wrote:
> The VXLAN driver currently does not check if the inner layer2
> source-address is valid.
> 
> In case source-address snooping/learning is enabled, a entry in the FDB
> for the invalid address is created with the layer3 address of the tunnel
> endpoint.
> 
> If the frame happens to have a non-unicast address set, all this
> non-unicast traffic is subsequently not flooded to the tunnel network
> but sent to the learnt host in the FDB. To make matters worse, this FDB
> entry does not expire.
> 
> Apply the same filtering for packets as it is done for bridges. This not
> only drops these invalid packets but avoids them from being learnt into
> the FDB.
> 
> Fixes: d342894c5d2f ("vxlan: virtual extensible lan")
> 
> Suggested-by: Ido Schimmel <idosch@nvidia.com>
> Signed-off-by: David Bauer <mail@david-bauer.net>

Reviewed-by: Ido Schimmel <idosch@nvidia.com>

Code looks fine, but there shouldn't be a blank line between the Fixes
tag and the other tags. Please wait 24h before reposting unless one of
the maintainers says otherwise:

https://docs.kernel.org/process/maintainer-netdev.html

Thanks