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

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Message-ID: <20230320182822.6xyh6ibatrz5yrhb@kernel.org>
Date:   Mon, 20 Mar 2023 20:28:22 +0200
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     Eric Snowberg <eric.snowberg@...cle.com>
Cc:     Mimi Zohar <zohar@...ux.ibm.com>,
        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, 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?

BR, Jarkko