linux-kernel - Re: [RFC PATCH 00/15] KEYS: Restrict additions to 'trusted' keyrings

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Date:	Tue, 12 Jan 2016 00:37:06 +0000
From:	David Howells <dhowells@...hat.com>
To:	Mimi Zohar <zohar@...ux.vnet.ibm.com>
Cc:	dhowells@...hat.com, linux-security-module@...r.kernel.org,
	keyrings@...r.kernel.org, petkan@...-labs.com,
	linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 00/15] KEYS: Restrict additions to 'trusted' keyrings

Mimi Zohar <zohar@...ux.vnet.ibm.com> wrote:

Mimi Zohar <zohar@...ux.vnet.ibm.com> wrote:

> > The kernel may add implicitly trusted keys to a trusted-only keyring by
> > asserting KEY_ALLOC_BYPASS_RESTRICTION when the key is created, but
> > otherwise the key will only be allowed to be added to the keyring if it can
> > be verified.  The system trusted keyring is not then special in this sense
> > and other trusted keyrings can be set up that are wholly independent of
> > it.
>
> In order to have a certificate chain of trust on any of these trusted
> keyrings, the system keyring needs to be special.  Even if we permit
> transitive trust, meaning keys on a keyring can be used to validate
> other keys being added to the same keyring, the first key added to a
> trusted keyring needs to be vetted against something.  That something
> needs to be the builtin keys on the system keyring.

Note that the KEY_ALLOC_BYPASS_RESTRICTION flag is there to permit built in
keys to be added by the kernel in the first place.  It would not be available
to userspace to use.

David