linux-kernel - Re: overlayfs vs. fscrypt

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Message-ID: <CAJfpegvX4ANfso-Jn1zaB+m4Q_0eK9i-+MCJ+sTH5QzD3PZFMQ@mail.gmail.com>
Date:   Thu, 14 Mar 2019 08:34:33 +0100
From:   Miklos Szeredi <miklos@...redi.hu>
To:     Richard Weinberger <richard@....at>
Cc:     Eric Biggers <ebiggers@...nel.org>,
        Amir Goldstein <amir73il@...il.com>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        linux-fscrypt@...r.kernel.org,
        overlayfs <linux-unionfs@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Paul Lawrence <paullawrence@...gle.com>
Subject: Re: overlayfs vs. fscrypt

On Wed, Mar 13, 2019 at 11:42 PM Richard Weinberger <richard@....at> wrote:
>
> Am Mittwoch, 13. März 2019, 23:26:11 CET schrieb Eric Biggers:

> > What specifically is wrong with supporting the ciphertext "view" of encrypted
> > directories, and why do you want to opt UBIFS out of it specifically but not
> > ext4 and f2fs?  (The fscrypt_operations are per-filesystem type, not
> > per-filesystem instance, so I assume that's what you had in mind.)  Note that we
> > can't unconditionally remove it because people need it to delete files without
> > the key.  We could add a mount option to disable it, but why exactly?
>
> You are right, fscrypt_operations is the wrong structure.
> My plan was having it per filesystem instance. So a mount-option seems like
> a good option. Of course for all filesystems that support fscrypt, not just UBIFS.

Yes, please.   Changing filesystem contents based on a mount option is
orders of magnitude more sane than doing so on key insertion/removal.

Thanks,
Miklos