Re: [PATCH v6 4/4] ima: Support EC keys for signature verification

[Tianjia Zhang <tianjia.zhang@linux.alibaba.com>]

On 2/1/21 7:33 AM, Stefan Berger wrote:
> Add support for IMA signature verification for EC keys. Since SHA type
> of hashes can be used by RSA and ECDSA signature schemes we need to
> look at the key and derive from the key which signature scheme to use.
> Since this can be applied to all types of keys, we change the selection
> of the encoding type to be driven by the key's signature scheme rather
> than by the hash type.
> 
> Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
> Reviewed-by: Vitaly Chikunov <vt@altlinux.org>
> Cc: Mimi Zohar <zohar@linux.ibm.com>
> Cc: Dmitry Kasatkin <dmitry.kasatkin@gmail.com>
> Cc: linux-integrity@vger.kernel.org
> Cc: Vitaly Chikunov <vt@altlinux.org>
> Cc: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
> Cc: David Howells <dhowells@redhat.com>
> Cc: keyrings@vger.kernel.org
> ---
>   include/keys/asymmetric-type.h         |  6 ++++++
>   security/integrity/digsig_asymmetric.c | 29 ++++++++++++--------------
>   2 files changed, 19 insertions(+), 16 deletions(-)
> 
> diff --git a/include/keys/asymmetric-type.h b/include/keys/asymmetric-type.h
> index a29d3ff2e7e8..c432fdb8547f 100644
> --- a/include/keys/asymmetric-type.h
> +++ b/include/keys/asymmetric-type.h
> @@ -72,6 +72,12 @@ const struct asymmetric_key_ids *asymmetric_key_ids(const struct key *key)
>   	return key->payload.data[asym_key_ids];
>   }
>   
> +static inline
> +const struct public_key *asymmetric_key_public_key(const struct key *key)
> +{
> +	return key->payload.data[asym_crypto];
> +}
> +
>   extern struct key *find_asymmetric_key(struct key *keyring,
>   				       const struct asymmetric_key_id *id_0,
>   				       const struct asymmetric_key_id *id_1,
> diff --git a/security/integrity/digsig_asymmetric.c b/security/integrity/digsig_asymmetric.c
> index a662024b4c70..29002d016607 100644
> --- a/security/integrity/digsig_asymmetric.c
> +++ b/security/integrity/digsig_asymmetric.c
> @@ -84,6 +84,7 @@ int asymmetric_verify(struct key *keyring, const char *sig,
>   {
>   	struct public_key_signature pks;
>   	struct signature_v2_hdr *hdr = (struct signature_v2_hdr *)sig;
> +	const struct public_key *pk;
>   	struct key *key;
>   	int ret;
>   
> @@ -105,23 +106,19 @@ int asymmetric_verify(struct key *keyring, const char *sig,
>   	memset(&pks, 0, sizeof(pks));
>   
>   	pks.hash_algo = hash_algo_name[hdr->hash_algo];
> -	switch (hdr->hash_algo) {
> -	case HASH_ALGO_STREEBOG_256:
> -	case HASH_ALGO_STREEBOG_512:
> -		/* EC-RDSA and Streebog should go together. */
> -		pks.pkey_algo = "ecrdsa";
> -		pks.encoding = "raw";
> -		break;
> -	case HASH_ALGO_SM3_256:
> -		/* SM2 and SM3 should go together. */
> -		pks.pkey_algo = "sm2";
> -		pks.encoding = "raw";
> -		break;
> -	default:
> -		pks.pkey_algo = "rsa";
> +
> +	pk = asymmetric_key_public_key(key);
> +	pks.pkey_algo = pk->pkey_algo;
> +	if (!strcmp(pk->pkey_algo, "rsa"))
>   		pks.encoding = "pkcs1";
> -		break;
> -	}
> +	else if (!strcmp(pk->pkey_algo, "ecdsa"))
> +		pks.encoding = "x962";
> +	else if (!strcmp(pk->pkey_algo, "ecrdsa") ||
> +		   !strcmp(pk->pkey_algo, "sm2"))
> +		pks.encoding = "raw";
> +	else
> +		return -ENOPKG;
> +
>   	pks.digest = (u8 *)data;
>   	pks.digest_size = datalen;
>   	pks.s = hdr->sig;
> 

Looks good to me, so

Reviewed-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>

Thanks,
Tianjia