linux-ext4 - Re: [RFC PATCH v3 07/18] fscrypt: add FS_IOC_ADD_ENCRYPTION

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Date:   Fri, 22 Mar 2019 23:02:49 +0100
From:   Richard Weinberger <richard@....at>
To:     Eric Biggers <ebiggers@...nel.org>
Cc:     linux-fscrypt@...r.kernel.org, Satya Tangirala <satyat@...gle.com>,
        "open list:ABI/API" <linux-api@...r.kernel.org>,
        linux-f2fs-devel@...ts.sourceforge.net, keyrings@...r.kernel.org,
        linux-mtd@...ts.infradead.org, linux-crypto@...r.kernel.org,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        linux-ext4@...r.kernel.org, Paul Crowley <paulcrowley@...gle.com>
Subject: Re: [RFC PATCH v3 07/18] fscrypt: add FS_IOC_ADD_ENCRYPTION_KEY ioctl

Ericm

Am Dienstag, 19. März 2019, 00:08:31 CET schrieb Eric Biggers:
> I tried using sb->s_bdi->name, but it's still "ubifs" for all UBIFS filesystems.

hmpf.
 
> Perhaps there's a way you can make ->s_id for UBIFS unique?  There are already
> existing places that log ->s_id, so perhaps you should do it anyway regardless
> of this patchset?

Yes, let me implement that.
ubifs does:
super_setup_bdi_name(sb, "ubifs_%d_%d", c->vi.ubi_num, c->vi.vol_id);

So, I try to set ->s_id also to ubifs_%d_%d.

> > > 
> > > > Note that the keyring name isn't particularly important, since the ioctls will
> > > > work regardless.  But we might as well choose something logical, since the
> > > > keyring name will still show up in /proc/keys.
> > > 
> > > I'm not done with reviewing your patches, but will it be possible to use keyctl?
> > > For the a unique name is helpful. :)
> > > 
> > 
> > Not for adding keys, removing keys, or getting a key's status -- those are what
> > the ioctls are for.
> > 
> > See e.g. the discussion in patch 7 ("fscrypt: add FS_IOC_ADD_ENCRYPTION_KEY
> > ioctl") for why the keyrings syscalls are a poor fit for fscrypt.
> > 
> 
> Anyway, perhaps I should reconsider whether fscrypt should even use the keyrings
> subsystem at all, even just "internally", as its quirks still leak out a bit.
> I'd prefer a nice clean API without any quirks like having to name the keyrings
> and assign SELinux labels to the keys just to make the keyrings subsystem happy.

IMHO the keys subsytem is a good fit. For example for stuff like this one:
https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1945778.html

We use UBIFS on many embedded systems with crypto hardware.

Thanks,
//richard