linux-kernel - Re: [PATCH v5 5/6] KEYS: CA link restriction

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Date:   Mon, 20 Mar 2023 16:35:33 -0400
From:   Mimi Zohar <zohar@...ux.ibm.com>
To:     Jarkko Sakkinen <jarkko@...nel.org>,
        Eric Snowberg <eric.snowberg@...cle.com>
Cc:     David Howells <dhowells@...hat.com>,
        David Woodhouse <dwmw2@...radead.org>,
        "herbert@...dor.apana.org.au" <herbert@...dor.apana.org.au>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "dmitry.kasatkin@...il.com" <dmitry.kasatkin@...il.com>,
        "paul@...l-moore.com" <paul@...l-moore.com>,
        "jmorris@...ei.org" <jmorris@...ei.org>,
        "serge@...lyn.com" <serge@...lyn.com>,
        "pvorel@...e.cz" <pvorel@...e.cz>,
        Kanth Ghatraju <kanth.ghatraju@...cle.com>,
        Konrad Wilk <konrad.wilk@...cle.com>,
        "erpalmer@...ux.vnet.ibm.com" <erpalmer@...ux.vnet.ibm.com>,
        "coxu@...hat.com" <coxu@...hat.com>,
        "keyrings@...r.kernel.org" <keyrings@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>,
        "linux-integrity@...r.kernel.org" <linux-integrity@...r.kernel.org>,
        "linux-security-module@...r.kernel.org" 
        <linux-security-module@...r.kernel.org>
Subject: Re: [PATCH v5 5/6] KEYS: CA link restriction

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@...nel.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@...cle.com>
> > >> Reviewed-by: Mimi Zohar <zohar@...ux.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.

-- 
Mimi