linux-ext4 - Re: [PATCH v7 12/16] fscrypt: require that key be added when setting a v2 encryption policy

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Message-ID: <20190728212402.GM6088@mit.edu>
Date:   Sun, 28 Jul 2019 17:24:02 -0400
From:   "Theodore Y. Ts'o" <tytso@....edu>
To:     Eric Biggers <ebiggers@...nel.org>
Cc:     linux-fscrypt@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-ext4@...r.kernel.org, linux-f2fs-devel@...ts.sourceforge.net,
        linux-mtd@...ts.infradead.org, linux-api@...r.kernel.org,
        linux-crypto@...r.kernel.org, keyrings@...r.kernel.org,
        Paul Crowley <paulcrowley@...gle.com>,
        Satya Tangirala <satyat@...gle.com>
Subject: Re: [PATCH v7 12/16] fscrypt: require that key be added when setting
 a v2 encryption policy

On Fri, Jul 26, 2019 at 03:41:37PM -0700, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@...gle.com>
> 
> By looking up the master keys in a filesystem-level keyring rather than
> in the calling processes' key hierarchy, it becomes possible for a user
> to set an encryption policy which refers to some key they don't actually
> know, then encrypt their files using that key.  Cryptographically this
> isn't much of a problem, but the semantics of this would be a bit weird.
> Thus, enforce that a v2 encryption policy can only be set if the user
> has previously added the key, or has capable(CAP_FOWNER).
> 
> We tolerate that this problem will continue to exist for v1 encryption
> policies, however; there is no way around that.
> 
> Signed-off-by: Eric Biggers <ebiggers@...gle.com>

Looks good, feel free to add:

Reviewed-by: Theodore Ts'o <tytso@....edu>

					- Ted