Re: [PATCH] xfrm: Use xfrm_state selector for BEET input

[Steffen Klassert <steffen.klassert@secunet.com>]

On Wed, Jun 07, 2023 at 04:38:47PM +0800, Herbert Xu wrote:
> On Tue, Jun 06, 2023 at 12:45:29PM +0200, Steffen Klassert wrote:
> >
> > the assumption that the L4 protocol on BEET mode can be
> > just IPIP or BEETPH seems not to be correct. One of
> > our testcaces hit the second WARN_ON_ONCE() in
> > xfrm_prepare_input. In that case the L4 protocol
> > is UDP. Looks like we need some other way to
> > dertermine the inner protocol family.
> 
> Oops, that was a thinko on my part:
> 
> ---8<---
> For BEET the inner address and therefore family is stored in the
> xfrm_state selector.  Use that when decapsulating an input packet
> instead of incorrectly relying on a non-existent tunnel protocol.
> 
> Fixes: 5f24f41e8ea6 ("xfrm: Remove inner/outer modes from input path")
> Reported-by: Steffen Klassert <steffen.klassert@secunet.com>
> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
> 
> diff --git a/net/xfrm/xfrm_input.c b/net/xfrm/xfrm_input.c
> index 39fb91ff23d9..bdaed1d1ff97 100644
> --- a/net/xfrm/xfrm_input.c
> +++ b/net/xfrm/xfrm_input.c
> @@ -330,11 +330,10 @@ xfrm_inner_mode_encap_remove(struct xfrm_state *x,
>  {
>  	switch (x->props.mode) {
>  	case XFRM_MODE_BEET:
> -		switch (XFRM_MODE_SKB_CB(skb)->protocol) {
> -		case IPPROTO_IPIP:
> -		case IPPROTO_BEETPH:
> +		switch (x->sel.family) {

Hm, I thought about that one too. But x->sel.family can
also be AF_UNSPEC, in which case we used the address
family of the inner mode before your change.

> +		case AF_INET:
>  			return xfrm4_remove_beet_encap(x, skb);
> -		case IPPROTO_IPV6:
> +		case AF_INET6:
>  			return xfrm6_remove_beet_encap(x, skb);
>  		}
>  		break;
> -- 
> Email: Herbert Xu <herbert@gondor.apana.org.au>
> Home Page: http://gondor.apana.org.au/~herbert/
> PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt