From: Mimi Zohar <zohar@linux.vnet.ibm.com>
Subject: Re: [PATCH v1.3 4/4] keys: add new key-type encrypted
Date: Mon, 15 Nov 2010 14:35:51 -0500
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Cc: linux-kernel@vger.kernel.org,
	linux-security-module@vger.kernel.org, keyrings@linux-nfs.org,
	linux-crypto@vger.kernel.org,
	Jason Gunthorpe <jgunthorpe@obsidianresearch.com>,
	James Morris <jmorris@namei.org>,
	David Safford <safford@watson.ibm.com>,
	Rajiv Andrade <srajiv@linux.vnet.ibm.com>,
	Mimi Zohar <zohar@us.ibm.com>
To: David Howells <dhowells@redhat.com>
In-Reply-To: <8268.1289837934@redhat.com>
Sender: linux-crypto-owner@vger.kernel.org

On Mon, 2010-11-15 at 16:18 +0000, David Howells wrote:
> Mimi Zohar <zohar@linux.vnet.ibm.com> wrote:

> > > But if you're going to use a user-defined key, you really need to prefix
> > > the description with something suitable.
> > 
> > Agreed. So instead of: 
> > 	keyctl add encrypted name "new master-key-name keylen" ring
> > 
> > the description would be prefixed with the key type like:	
> > 	keyctl add encrypted name "new trusted|user master-key-name keylen" ring
> 
> I don't think you understood what I meant.  If you look at the following
> function:

> +static struct key *request_master_key(struct encrypted_key_payload *epayload,
> +	       	   			void **master_key,
> +					unsigned int *master_keylen)
> +{
> +	struct key *mkey;
> +
> +	mkey = request_trusted_key(epayload->master_desc,
> +				   master_key, master_keylen);
> +	if (IS_ERR(mkey)) {
> +		mkey = request_user_key(epayload->master_desc,
> +					master_key, master_keylen);
> +		if (IS_ERR(mkey)) {
> +			pr_info("encrypted_key: trusted/user key %s not found",
> +				epayload->master_desc);
> +			return mkey;
> +		}
> +	}
> +	dump_master_key(*master_key, *master_keylen);
> +	return mkey;
> +}
> 
> In the bit where you go for a user key (having failed to get a trusted key),
> you should prefix the description here (or in request_user_key()) with
> something like "trusted:".  Then you don't need to change the user interface.
> 
> David

Am assuming you mean something like this:

keyctl add encrypted name "new trusted:master-key-name keylen" ring
keyctl add encrypted name "new user:master-key-name keylen" ring

and, as you said, works without changing the API.

thanks,

Mimi