netdev - Re: [Patch net] xfrm: unify xfrm protocol checks

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Message-ID: <20190319051739.kevpimikwthni65k@gondor.apana.org.au>
Date:   Tue, 19 Mar 2019 13:17:39 +0800
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     Cong Wang <xiyou.wangcong@...il.com>
Cc:     netdev@...r.kernel.org,
        syzbot+0bf0519d6e0de15914fe@...kaller.appspotmail.com,
        Steffen Klassert <steffen.klassert@...unet.com>
Subject: Re: [Patch net] xfrm: unify xfrm protocol checks

On Mon, Mar 18, 2019 at 10:08:24PM -0700, Cong Wang wrote:
>
> +static inline bool xfrm_id_proto_valid(u8 proto)
> +{
> +	switch (proto) {
> +	case IPPROTO_AH:
> +	case IPPROTO_ESP:
> +	case IPPROTO_COMP:
> +#if IS_ENABLED(CONFIG_IPV6)
> +	case IPPROTO_ROUTING:
> +	case IPPROTO_DSTOPTS:
> +#endif
> +	case IPSEC_PROTO_ANY:
> +		return true;
> +	default:
> +		return false;
> +	}
> +}
> +
>  static inline int xfrm_id_proto_match(u8 proto, u8 userproto)
>  {
>  	return (!userproto || proto == userproto ||
> -		(userproto == IPSEC_PROTO_ANY && (proto == IPPROTO_AH ||
> -						  proto == IPPROTO_ESP ||
> -						  proto == IPPROTO_COMP)));
> +		(userproto == IPSEC_PROTO_ANY && xfrm_id_proto_valid(proto)));
>  }

This does not look right.  IPSEC_PROTO_ANY should only be allowed
in userproto and your patch is going to let it pass when it's in
proto.  Whether IPPROTO_ROUTING/IPPROTO_DSTOPTS should be allowed
in this context is also not obvious.

Cheers,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt