[PATCH 3/4] KEYS: CA link restriction

[Eric Snowberg]

> On Mar 4, 2022, at 8:28 AM, Stefan Berger <stefanb at linux.ibm.com> wrote:
> 
> 
> On 3/1/22 12:36, Eric Snowberg wrote:
>> Add a new link restriction.  Restrict the addition of keys in a keyring
>> based on the key to be added being a CA.
>> 
>> Signed-off-by: Eric Snowberg <eric.snowberg at oracle.com>
>> ---
>>  crypto/asymmetric_keys/restrict.c | 43 +++++++++++++++++++++++++++++++
>>  include/crypto/public_key.h       | 15 +++++++++++
>>  2 files changed, 58 insertions(+)
>> 
>> diff --git a/crypto/asymmetric_keys/restrict.c b/crypto/asymmetric_keys/restrict.c
>> index 6b1ac5f5896a..49bb2ea7f609 100644
>> --- a/crypto/asymmetric_keys/restrict.c
>> +++ b/crypto/asymmetric_keys/restrict.c
>> @@ -108,6 +108,49 @@ int restrict_link_by_signature(struct key *dest_keyring,
>>  	return ret;
>>  }
>>  +/**
>> + * restrict_link_by_ca - Restrict additions to a ring of CA keys
>> + * @dest_keyring: Keyring being linked to.
>> + * @type: The type of key being added.
>> + * @payload: The payload of the new key.
>> + * @trust_keyring: Unused.
>> + *
>> + * Check if the new certificate is a CA. If it is a CA, then mark the new
>> + * certificate as being ok to link.
> 
> CA = root CA here, right?

Yes, I’ll update the comment

>> + *
>> + * Returns 0 if the new certificate was accepted, -ENOKEY if the
>> + * certificate is not a CA. -ENOPKG if the signature uses unsupported
>> + * crypto, or some other error if there is a matching certificate but
>> + * the signature check cannot be performed.
>> + */
>> +int restrict_link_by_ca(struct key *dest_keyring,
>> +			const struct key_type *type,
>> +			const union key_payload *payload,
>> +			struct key *trust_keyring)
> This function needs to correspond to the key_restrict_link_func_t and therefore has 4 parameter. Call the unused 'trust_keyring' 'unused' instead?

and I’ll change the name in the next round.