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

[Dan Williams]

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.