Casey Schaufler [off-list ref] 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?