Re: [PATCH net 1/2] net/iucv: drop HiperSockets frames from other network namespaces

[Alexandra Winter <wintera@linux.ibm.com>]

On 15.08.26 18:07, Bryam Vargas via B4 Relay wrote:
> From: Bryam Vargas <hexlabsecurity@proton.me>
> 
> iucv_packet_type sets neither .dev nor .af_packet_net, so it lands in the
> machine-global ptype_base[] that __netif_receive_skb_core walks for every
> frame in every namespace, and afiucv_hs_rcv() ignores its dev argument.
> An ETH_P_AF_IUCV frame sent from any namespace holding CAP_NET_RAW is
> therefore matched against the global iucv_sk_list and can move a socket
> owned by the initial namespace: afiucv_hs_callback_synfin() and _fin()
> overwrite its sk_state, and _syn() builds an accept-queue child.
> 
> Filter on the namespace. The core does not do it for ptype_base[] --
> net/core/dev.c leaves namespace filtering to the ptype owner -- and
> net/x25/x25_dev.c and net/ieee802154/socket.c both test dev_net(dev) at
> exactly this point.
> 
> Fixes: 3881ac441f64 ("af_iucv: add HiperSockets transport")
> Cc: stable@vger.kernel.org
> Signed-off-by: Bryam Vargas <hexlabsecurity@proton.me>
> ---
>  net/iucv/af_iucv.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/net/iucv/af_iucv.c b/net/iucv/af_iucv.c
> index ea047bab65e7..e3ec965d96ca 100644
> --- a/net/iucv/af_iucv.c
> +++ b/net/iucv/af_iucv.c
> @@ -2064,6 +2064,11 @@ static int afiucv_hs_rcv(struct sk_buff *skb, struct net_device *dev,
>  	int err = NET_RX_SUCCESS;
>  	char nullstring[8];
>  
> +	if (!net_eq(dev_net(dev), &init_net)) {
> +		kfree_skb(skb);
> +		return NET_RX_SUCCESS;
> +	}
> +
>  	if (!pskb_may_pull(skb, sizeof(*trans_hdr))) {
>  		kfree_skb(skb);
>  		return NET_RX_SUCCESS;
> 

I am wondering whether a check of
+		if (iucv_sk(sk)->hs_dev != dev)
+			continue;

would cover a broader range of issues.
I'll try to send a proper patch proposal.