netdev - Re: [PATCH net] bareudp: forbid mixing IP and MPLS in multiproto mode

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Message-ID: <20200724162134.7b0c8aaa@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Date:   Fri, 24 Jul 2020 16:21:34 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Guillaume Nault <gnault@...hat.com>
Cc:     David Miller <davem@...emloft.net>, netdev@...r.kernel.org,
        Martin Varghese <martin.varghese@...ia.com>,
        Willem de Bruijn <willemb@...gle.com>
Subject: Re: [PATCH net] bareudp: forbid mixing IP and MPLS in multiproto
 mode

On Fri, 24 Jul 2020 23:03:26 +0200 Guillaume Nault wrote:
> In multiproto mode, bareudp_xmit() accepts sending multicast MPLS and
> IPv6 packets regardless of the bareudp ethertype. In practice, this
> let an IP tunnel send multicast MPLS packets, or an MPLS tunnel send
> IPv6 packets.
> 
> We need to restrict the test further, so that the multiproto mode only
> enables
>   * IPv6 for IPv4 tunnels,
>   * or multicast MPLS for unicast MPLS tunnels.
> 
> To improve clarity, the protocol validation is moved to its own
> function, where each logical test has its own condition.
> 
> Fixes: 4b5f67232d95 ("net: Special handling for IP & MPLS.")
> Signed-off-by: Guillaume Nault <gnault@...hat.com>

Hi! this adds 10 sparse warnings:

drivers/net/bareudp.c:419:22: warning: cast to restricted __be16
drivers/net/bareudp.c:419:22: warning: cast to restricted __be16
drivers/net/bareudp.c:419:22: warning: cast to restricted __be16
drivers/net/bareudp.c:419:22: warning: cast to restricted __be16
drivers/net/bareudp.c:419:13: warning: restricted __be16 degrades to integer
drivers/net/bareudp.c:423:22: warning: cast to restricted __be16
drivers/net/bareudp.c:423:22: warning: cast to restricted __be16
drivers/net/bareudp.c:423:22: warning: cast to restricted __be16
drivers/net/bareudp.c:423:22: warning: cast to restricted __be16

I think this:

	    proto == ntohs(ETH_P_MPLS_MC))

has to say htons() not ntohs(). For v6 as well.