Re: [PATCH 2/6] security/keys/encrypted: Clean up request_trusted_key()

[Mimi Zohar]

On Tue, 2019-03-19 at 22:48 -0700, Dan Williams wrote:
> On Tue, Mar 19, 2019 at 7:36 PM Mimi Zohar <zohar@xxxxxxxxxxxxx> wrote:
> >
> > On Tue, 2019-03-19 at 17:20 -0700, Dan Williams wrote:
> > > On Tue, Mar 19, 2019 at 5:07 PM Mimi Zohar <zohar@xxxxxxxxxxxxx> wrote:
> > > >
> > > > On Mon, 2019-03-18 at 23:06 -0700, Dan Williams wrote:
> > > >
> > > > < snip >
> > > >
> > > > > +/*
> > > > > + * request_trusted_key - request the trusted key
> > > > > + *
> > > > > + * Trusted keys are sealed to PCRs and other metadata. Although userspace
> > > > > + * manages both trusted/encrypted key-types, like the encrypted key type
> > > > > + * data, trusted key type data is not visible decrypted from userspace.
> > > > > + */
> > > > > +static struct key *request_trusted_key(const char *trusted_desc,
> > > > > +                             const u8 **master_key, size_t *master_keylen)
> > > > > +{
> > > > > +     struct trusted_key_payload *tpayload;
> > > > > +     struct key_type *type;
> > > > > +     struct key *tkey;
> > > > > +
> > > > > +     type = key_type_lookup("trusted");
> > > >
> > > > The associated key_type_put() will need to be called.
> > >
> > > Yes.
> >
> > I don't know if defining a key_type_lookup() wrapper, perhaps named
> > is_key_type_available(), would help.  Both key_type_lookup() and
> > key_type_put() would be called.  The existing code could then remain
> > the same.
> >
> 
> Maybe, but something still needs to pin the hosting module. I think
> this means that the first call to key_type->instantiate() pins the
> hosting module, and the ->destroy() of the last key for the key_type
> unpins the module. It does mean that the ->destroy() method is no
> longer optional.

This sounds like it isn't a new problem. ÂBoth issues need to be
addressed, but I think we should differentiate between them and
address them separately.

In terms of the original nvdimm encrypted/trusted key problem, the
above suggestion requires the least amount of change. ÂFor v5.2, I
would replace it with the full updated patch set.

Mimi