Re: [PATCH v5 02/12] libnvdimm: create keyring to store security keys

[Dave Jiang <dave.jiang@intel.com>]

On 07/18/2018 03:50 AM, David Howells wrote:
> Dave Jiang <dave.jiang@intel.com> wrote:
> 
>> +static int nvdimm_key_instantiate(struct key *key,
>> +		struct key_preparsed_payload *prep)
> 
> Please use ->preparse() if you can rather than doing this in ->instantiate().
> Ideally ->instantiate() should not return an error, particularly not -EINVAL
> or -ENOMEM.
> 
>> +{
>> +	char *payload;
>> +
>> +	payload = kzalloc(nvdimm_key_type.def_datalen, GFP_KERNEL);
>> +	if (!payload)
>> +		return -ENOMEM;
> 
> Ummm...  Why not just kmemdup()?  Why not use use prep->datalen here rather
> than def_datalen?
> 
>> +
>> +	key->datalen = min(nvdimm_key_type.def_datalen, prep->datalen);
>> +	memcpy(payload, prep->data, key->datalen);
>> +	key->payload.data[0] = payload;
>> +	return 0;
>> +}
> 
> I would recommend, firstly, that you use generic_key_instantiate() if you can;
> if not, you might want to use rcu_assign_keypointer().
> 
>> +	cred = prepare_kernel_cred(NULL);
>> +	if (!cred) {
>> +		rc = -ENOMEM;
>> +		goto failed_cred;
>> +	}
> 
> I wonder if you could just use &init_cred instead.

You mean also instead of a dedicated keyring, just use the existing ones
that comes with init_cred as well?

> 
> David
> 
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