linux-kernel - Re: [PATCH 2/6] security/keys/encrypted: Clean up request_trusted

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Date:   Tue, 19 Mar 2019 17:20:01 -0700
From:   Dan Williams <dan.j.williams@...el.com>
To:     Mimi Zohar <zohar@...ux.ibm.com>
Cc:     keyrings@...r.kernel.org, James Bottomley <jejb@...ux.ibm.com>,
        David Howells <dhowells@...hat.com>,
        Vishal L Verma <vishal.l.verma@...el.com>,
        linux-nvdimm <linux-nvdimm@...ts.01.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/6] security/keys/encrypted: Clean up request_trusted_key()

On Tue, Mar 19, 2019 at 5:07 PM Mimi Zohar <zohar@...ux.ibm.com> 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.

>
> > +     if (IS_ERR(type)) {
> > +             tkey = (struct key *)type;
> > +             goto error;
> > +     }
> > +     tkey = request_key(type, trusted_desc, NULL);
> > +     if (IS_ERR(tkey))
> > +             goto error;
> > +
> > +     down_read(&tkey->sem);
> > +     tpayload = tkey->payload.data[0];
> > +     *master_key = tpayload->key;
> > +     *master_keylen = tpayload->key_len;
> > +error:
> > +     return tkey;
> > +}
> > +
>
>
>
> > diff --git a/security/keys/key.c b/security/keys/key.c
> > index 696f1c092c50..9045b62afb04 100644
> > --- a/security/keys/key.c
> > +++ b/security/keys/key.c
> > @@ -706,6 +706,7 @@ struct key_type *key_type_lookup(const char *type)
> >  found_kernel_type:
> >       return ktype;
> >  }
> > +EXPORT_SYMBOL_GPL(key_type_lookup);

This needs to be moved to patch1.

> Only the kernel is calling key_type_lookup().  Why does
> key_type_lookup() need to be exported?

This patch series adds several new callers outside of keys-subsystem
core that need this export, the first one being encrypted-keys itself
in patch1.

drivers/nvdimm/security.c:57:   type = key_type_lookup("encrypted");
fs/ecryptfs/keystore.c:1627:    type = key_type_lookup("encrypted");
security/integrity/evm/evm_crypto.c:361:        type =
key_type_lookup("encrypted");
security/keys/encrypted-keys/encrypted.c:440:   type =
key_type_lookup("trusted");