[PATCH v5 5/6] KEYS: CA link restriction

[Jarkko Sakkinen]

On Mon, Mar 20, 2023 at 04:35:33PM -0400, Mimi Zohar wrote:
> On Mon, 2023-03-20 at 20:28 +0200, Jarkko Sakkinen wrote:
> > On Mon, Mar 20, 2023 at 05:35:05PM +0000, Eric Snowberg wrote:
> > > 
> > > 
> > > > On Mar 11, 2023, at 3:10 PM, Jarkko Sakkinen <jarkko at kernel.org> wrote:
> > > > 
> > > > On Thu, Mar 02, 2023 at 11:46:51AM -0500, 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>
> > > >> Reviewed-by: Mimi Zohar <zohar at linux.ibm.com>
> > > >> ---
> > > >> crypto/asymmetric_keys/restrict.c | 38 +++++++++++++++++++++++++++++++
> > > >> include/crypto/public_key.h       | 15 ++++++++++++
> > > >> 2 files changed, 53 insertions(+)
> > > >> 
> > > >> diff --git a/crypto/asymmetric_keys/restrict.c b/crypto/asymmetric_keys/restrict.c
> > > >> index 6b1ac5f5896a..48457c6f33f9 100644
> > > >> --- a/crypto/asymmetric_keys/restrict.c
> > > >> +++ b/crypto/asymmetric_keys/restrict.c
> > > >> @@ -108,6 +108,44 @@ 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.
> > > >> + *
> > > >> + * 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)
> > > >> +{
> > > >> +	const struct public_key *pkey;
> > > >> +
> > > >> +	if (type != &key_type_asymmetric)
> > > >> +		return -EOPNOTSUPP;
> > > >> +
> > > >> +	pkey = payload->data[asym_crypto];
> > > >> +	if (!pkey)
> > > >> +		return -ENOPKG;
> > > >> +	if (!test_bit(KEY_EFLAG_CA, &pkey->key_eflags))
> > > >> +		return -ENOKEY;
> > > >> +	if (!test_bit(KEY_EFLAG_KEYCERTSIGN, &pkey->key_eflags))
> > > >> +		return -ENOKEY;
> > > >> +	if (test_bit(KEY_EFLAG_DIGITALSIG, &pkey->key_eflags))
> > > >> +		return -ENOKEY;
> > > > 
> > > > nit: would be more readable, if conditions were separated by
> > > > empty lines.
> > > 
> > > Ok, I will make this change in the next round.  Thanks.
> > 
> > Cool! Mimi have you tested these patches with IMA applied?
> 
> Yes, it's working as expected.

Thank you. Please check that I filled additional tags correctly:

https://git.kernel.org/pub/scm/linux/kernel/git/jarkko/linux-tpmdd.git/log/

I will then put these also to my 'next' branch and they will get mirrored
to linux-next.

BR, Jarkko