From: Mimi Zohar <zohar@linux.ibm.com>
To: Jarkko Sakkinen <jarkko@kernel.org>,
Ahmad Fatoum <a.fatoum@pengutronix.de>,
James Bottomley <jejb@linux.ibm.com>,
David Howells <dhowells@redhat.com>,
keyrings@vger.kernel.org
Cc: linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-security-module@vger.kernel.org, kernel@pengutronix.de,
jlu@pengutronix.de
Subject: Re: Migration to trusted keys: sealing user-provided key?
Date: Sun, 31 Jan 2021 07:09:55 -0500 [thread overview]
Message-ID: <d1bed49f89495ceb529355cb41655a208fdb2197.camel@linux.ibm.com> (raw)
In-Reply-To: <6dc99fd9ffbc5f405c5f64d0802d1399fc6428e4.camel@kernel.org>
On Sat, 2021-01-30 at 19:53 +0200, Jarkko Sakkinen wrote:
> On Thu, 2021-01-28 at 18:31 +0100, Ahmad Fatoum wrote:
> > Hello,
> >
> > I've been looking into how a migration to using trusted/encrypted keys
> > would look like (particularly with dm-crypt).
> >
> > Currently, it seems the the only way is to re-encrypt the partitions
> > because trusted/encrypted keys always generate their payloads from
> > RNG.
> >
> > If instead there was a key command to initialize a new trusted/encrypted
> > key with a user provided value, users could use whatever mechanism they
> > used beforehand to get a plaintext key and use that to initialize a new
> > trusted/encrypted key. From there on, the key will be like any other
> > trusted/encrypted key and not be disclosed again to userspace.
> >
> > What are your thoughts on this? Would an API like
> >
> > keyctl add trusted dmcrypt-key 'set <content>' # user-supplied content
> >
> > be acceptable?
>
> Maybe it's the lack of knowledge with dm-crypt, but why this would be
> useful? Just want to understand the bottleneck, that's all.
We upstreamed "trusted" & "encrypted" keys together in order to address
this sort of problem. Instead of directly using a "trusted" key for
persistent file signatures being stored as xattrs, the "encrypted" key
provides one level of indirection. The "encrypted" key may be
encrypted/decrypted with either a TPM based "trusted" key or with a
"user" type symmetric key[1].
Instead of modifying "trusted" keys, use a "user" type "encrypted" key.
Mimi
[1] The ima-evm-utils README contains EVM examples of "trusted" and
"user" based "encrypted" keys.
next prev parent reply other threads:[~2021-01-31 15:38 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-28 17:31 Migration to trusted keys: sealing user-provided key? Ahmad Fatoum
2021-01-30 17:53 ` Jarkko Sakkinen
2021-01-30 18:07 ` James Bottomley
2021-01-31 12:09 ` Mimi Zohar [this message]
2021-01-31 14:14 ` Jan Lübbe
2021-01-31 18:09 ` James Bottomley
2021-02-02 12:15 ` Sumit Garg
2021-02-02 12:34 ` Jan Lübbe
2021-02-03 11:50 ` Sumit Garg
2021-02-03 13:46 ` Jan Lübbe
2021-02-04 5:30 ` Sumit Garg
[not found] ` <d4eeefa0c13395e91850630e22d0d9e3690f43ac.camel@linux.ibm.com>
2021-02-01 15:31 ` Jan Lübbe
2021-02-01 16:11 ` Mimi Zohar
2021-02-01 16:38 ` Jan Lübbe
2021-02-01 19:46 ` Mimi Zohar
2021-02-08 14:38 ` Jan Lübbe
2021-02-08 21:50 ` Mimi Zohar
2021-02-09 7:16 ` Jan Lübbe
2021-02-01 11:36 ` David Howells
2021-02-01 15:50 ` Jan Lübbe
2021-02-01 17:04 ` David Howells
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