Re: [PATCH ima-evm-utils v2] ima-evm-utils: Support SM2 algorithm for sign and verify

[Mimi Zohar <zohar@linux.ibm.com>]

Hi Tianjia,

On Thu, 2021-02-11 at 13:22 +0800, Tianjia Zhang wrote:
> The combination of SM2 and SM3 algorithms has been implemented in the
> kernel. At present, the ima-evm-utils signature tool does not support
> this combination of algorithms. Because in the current version of
> OpenSSL 1.1.1, the SM2 algorithm and the public key using the EC
> algorithm share the same ID 'EVP_PKEY_EC', and the specific algorithm
> can only be distinguished by the curve name used. This patch supports
> this feature.
> 
> Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
> ---
>  src/libimaevm.c | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
> 
> diff --git a/src/libimaevm.c b/src/libimaevm.c
> index fa6c278..589dd09 100644
> --- a/src/libimaevm.c
> +++ b/src/libimaevm.c
> @@ -518,6 +518,16 @@ static int verify_hash_v2(const char *file, const unsigned char *hash, int size,
>  		return -1;
>  	}
>  
> +#ifdef EVP_PKEY_SM2
> +	/* If EC key are used, check whether it is SM2 key */
> +	if (EVP_PKEY_id(pkey) == EVP_PKEY_EC) {
> +		EC_KEY *ec = EVP_PKEY_get0_EC_KEY(pkey);
> +		int curve = EC_GROUP_get_curve_name(EC_KEY_get0_group(ec));
> +		if (curve == NID_sm2)
> +			EVP_PKEY_set_alias_type(pkey, EVP_PKEY_SM2);
> +	}
> +#endif
> +

Suppose a file is signed on one system and verified on another.  What
happens if EVP_PKEY_SM2 is defined on one system, but not the other? 
Since the signing/verifying code do exactly the same thing, a
sign_verify test wouldn't detect the problem.   In anycase, please
define a sign_verify test.

thanks,

Mimi


>  	st = "EVP_PKEY_CTX_new";
>  	if (!(ctx = EVP_PKEY_CTX_new(pkey, NULL)))
>  		goto err;
> @@ -932,6 +942,16 @@ static int sign_hash_v2(const char *algo, const unsigned char *hash,
>  		return -1;
>  	}
>  
> +#ifdef EVP_PKEY_SM2
> +	/* If EC key are used, check whether it is SM2 key */
> +	if (EVP_PKEY_id(pkey) == EVP_PKEY_EC) {
> +		EC_KEY *ec = EVP_PKEY_get0_EC_KEY(pkey);
> +		int curve = EC_GROUP_get_curve_name(EC_KEY_get0_group(ec));
> +		if (curve == NID_sm2)
> +			EVP_PKEY_set_alias_type(pkey, EVP_PKEY_SM2);
> +	}
> +#endif
> +
>  	calc_keyid_v2(&keyid, name, pkey);
>  	hdr->keyid = keyid;
>