Re: [RFC PATCH] ima-evm-utils: convert sign v2 from RSA to EVP_PKEY API

[Vitaly Chikunov <vt@altlinux.org>]

On Mon, Jan 28, 2019 at 08:11:53PM +0300, Vitaly Chikunov wrote:
> Convert sign_v2 and related to using EVP_PKEY API instead of RSA API.
> This enables more signatures to work out of the box.
> 
> Only in single instance GOST NIDs are checked to produce correct keyid.
> Other than that code is quite generic.

There is was to generalize it a bit more.

> Remove RSA_ASN1_templates[] as it does not needed anymore. OpenSSL sign
> is doing proper PKCS1 padding automatically (tested to be compatible
> with previous version, except for MD4). This also fixes bug with MD4
> which produced wrong signature because of absence of the appropriate
> RSA_ASN1_template.
> 
> Signed-off-by: Vitaly Chikunov <vt@altlinux.org>
> ---
>  src/evmctl.c    |  25 +++---
>  src/imaevm.h    |   4 +-
>  src/libimaevm.c | 271 +++++++++++++++++++++++++++-----------------------------
>  3 files changed, 146 insertions(+), 154 deletions(-)
> 
> diff --git a/src/libimaevm.c b/src/libimaevm.c
> index d9ffa13..bd99c60 100644
> --- a/src/libimaevm.c
> +++ b/src/libimaevm.c
> @@ -776,16 +724,32 @@ void calc_keyid_v1(uint8_t *keyid, char *str, const unsigned char *pkey, int len
>  		log_info("keyid-v1: %s\n", str);
>  }
>  
> -void calc_keyid_v2(uint32_t *keyid, char *str, RSA *key)
> +void calc_keyid_v2(uint32_t *keyid, char *str, EVP_PKEY *key)
>  {
> +	X509_PUBKEY *pk = NULL;
>  	uint8_t sha1[SHA_DIGEST_LENGTH];
> -	unsigned char *pkey = NULL;
> +	const unsigned char *pkey = NULL;
> +	unsigned char *pp = NULL;
>  	int len;
>  
> -	len = i2d_RSAPublicKey(key, &pkey);
> -
> -	SHA1(pkey, len, sha1);
> +	switch (EVP_PKEY_id(key)) {
> +	case NID_id_GostR3410_2012_256:
> +	case NID_id_GostR3410_2012_512:
> +		X509_PUBKEY_set(&pk, key);
> +		X509_PUBKEY_get0_param(NULL, &pkey, &len, NULL, pk);
> +		break;
> +	default:
> +		len = i2d_PublicKey(key, &pp);

Because two calls to X509_PUBKEY_set and X509_PUBKEY_get0_param can
handle more keys (including RSA), call to i2d_PublicKey could be
avoided, so switch with Gost NIDs could be removed too. Tested.

> +		pkey = pp;
> +	}
>  
> +	if (len <= 0) {
> +		ERR_print_errors_fp(stderr);
> +		/* Produce invalid key in case of error. */
> +		len = SHA_DIGEST_LENGTH;
> +		memset(sha1, 0, len);
> +	} else
> +		SHA1(pkey, len, sha1);
>  	/* sha1[12 - 19] is exactly keyid from gpg file */
>  	memcpy(keyid, sha1 + 16, 4);
>  	log_debug("keyid: ");