Re: [PATCH] security/keys/trusted: Allow operation without hardware TPM

[Mimi Zohar]

Hi Dan,

On Mon, 2019-03-18 at 17:30 -0700, Dan Williams wrote:

Sorry for the late reply.

> On Mon, Mar 18, 2019 at 5:24 PM James Bottomley <jejb@xxxxxxxxxxxxx> wrote:
> >
> > On Mon, 2019-03-18 at 16:45 -0700, Dan Williams wrote:
> > > Rather than fail initialization of the trusted.ko module, arrange for
> > > the module to load, but rely on trusted_instantiate() to fail
> > > trusted-key operations.
> >
> > What actual problem is this fixing?  To me it would seem like an
> > enhancement to make the trusted module fail at load time if there's no
> > TPM rather than waiting until first use to find out it can never work.
> > Is there some piece of user code that depends on the successful
> > insertion of trusted.ko?
> 
> The module dependency chain relies on it. If that can be broken that
> would also be an acceptable fix.
> 
> I found this through the following dependency chain: libnvdimm.ko ->
> encrypted_keys.ko -> trusted.ko.
> 
> "key_type_trusted" is the symbol that encrypted_keys needs regardless
> of whether the tpm is present.

CommitÂ982e617a313b ("encrypted-keys: remove trusted-keys dependency")
removed the dependency on trusted keys. Âmasterkey_trusted.c should
only be included if "CONFIG_TRUSTED_KEYS" is enabled. ÂIs
CONFIG_TRUSTED_KEYS enabled?

Mimi