[PATCH 4/6] fscrypt: verify that the correct master key was supplied

[Jeffrey Walton]

On Wed, Jul 12, 2017 at 5:00 PM, Eric Biggers <ebiggers3 at gmail.com> wrote:
> From: Eric Biggers <ebiggers at google.com>
>
>....
> Solve the problem for v2 encryption policies by storing a "hash" of the
> master encryption key in the encryption xattr and verifying it before
> accepting the user-provided key.
> ...

Forgive my ignorance... Doesn't that setup an oracle so an attacker
can query keys?

It seems like the problem is deeper into the design. Namely, the
caching and sharing of keys.

Jeff