New skb extension for use by LSMs (skb "security blob")?

[Florian Westphal]

Casey Schaufler <casey at schaufler-ca.com> wrote:
> Given that the original objection to using a skb extension for a
> security blob was that an extension is dynamic, and that the ubiquitous
> nature of LSM use makes that unreasonable, it would seem that supporting
> the security blob as a basic part if the skb would be the obvious and
> correct solution. If the normal case is that there is an LSM that would
> befit from the native (unextended) support of a blob, it would seem
> that that is the case that should be optimized.

What is this "blob"? i.e., what would you like to add to sk_buff to make
whatever use cases you have in mind work?