netdev - [PATCH net v2] vxlan: drop packets from invalid src-address

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Message-ID: <20240418132908.38032-1-mail@david-bauer.net>
Date: Thu, 18 Apr 2024 15:29:08 +0200
From: David Bauer <mail@...id-bauer.net>
To: davem@...emloft.net,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com,
	amcohen@...dia.com
Cc: netdev@...r.kernel.org,
	Ido Schimmel <idosch@...dia.com>
Subject: [PATCH net v2] vxlan: drop packets from invalid src-address

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@...dia.com>
Signed-off-by: David Bauer <mail@...id-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