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

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Message-ID: <20240401030408.GA1638983@maili.marvell.com>
Date: Mon, 1 Apr 2024 08:34:08 +0530
From: Ratheesh Kannoth <rkannoth@...vell.com>
To: David Bauer <mail@...id-bauer.net>
CC: <davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
        <pabeni@...hat.com>, <amcohen@...dia.com>, <netdev@...r.kernel.org>,
        Ido
 Schimmel <idosch@...dia.com>
Subject: Re: [PATCH net-next] vxlan: drop packets from invalid src-address

On 2024-04-01 at 02:44:34, David Bauer (mail@...id-bauer.net) 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.
what is root cause of creation of invalid MAC from an L3 address ? could you
add that as well to commit message.

>
> 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.
>
> 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
>