linux-ext4 - Re: [PATCH] fscrypto: add authorization check for setting encryption policy

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Message-ID: <20160910033759.qsvg4loedccqc7if@thunk.org>
Date:   Fri, 9 Sep 2016 23:37:59 -0400
From:   Theodore Ts'o <tytso@....edu>
To:     Eric Biggers <ebiggers@...gle.com>
Cc:     linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org,
        linux-f2fs@...r.kernel.org, jaegeuk@...nel.org
Subject: Re: [PATCH] fscrypto: add authorization check for setting encryption
 policy

On Thu, Sep 08, 2016 at 10:57:08AM -0700, Eric Biggers wrote:
> On an ext4 or f2fs filesystem with file encryption supported, a user
> could set an encryption policy on any empty directory(*) to which they
> had readonly access.  This is obviously problematic, since such a
> directory might be owned by another user and the new encryption policy
> would prevent that other user from creating files in their own directory
> (for example).
> 
> Fix this by requiring inode_owner_or_capable() permission to set an
> encryption policy.  This means that either the caller must own the file,
> or the caller must have the capability CAP_FOWNER.
> 
> (*) Or also on any regular file, for f2fs v4.6 and later and ext4
>     v4.8-rc1 and later; a separate bug fix is coming for that.
> 
> Signed-off-by: Eric Biggers <ebiggers@...gle.com>
> Cc: stable@...r.kernel.org # 4.1+; check fs/{ext4,f2fs}

Thanks, applied.  (Jaeguk, I plan to send this to Linus via the
ext4.git tree as a fix for v4.8)

					- Ted
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