Re: [ima-evm-utils PATCH 12/12] Define and use a file specific "keypass" variable

[Stefan Berger <stefanb@linux.ibm.com>]

On 11/19/23 11:50, Mimi Zohar wrote:
> Instead of relying on the "imaevm_params.keypass" global variable, which
> is not concurrency-safe, add keypass as a parameter to the static library
> functions definitions.  Update function callers.
> 
> To avoid library incompatablity, don't remove imaevm_params.keypass
> variable.
> 
> Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
> ---
>   src/evmctl.c    |  9 +++++----
>   src/libimaevm.c | 17 ++++++++---------
>   2 files changed, 13 insertions(+), 13 deletions(-)
> 
> diff --git a/src/evmctl.c b/src/evmctl.c
> index b802eeb1bf15..6d6160159a1f 100644
> --- a/src/evmctl.c
> +++ b/src/evmctl.c
> @@ -141,6 +141,7 @@ static bool evm_portable;
>   static bool veritysig;
>   static bool hwtpm;
>   static char *hash_algo;
> +static char *keypass;
>   
>   #define HMAC_FLAG_NO_UUID	0x0001
>   #define HMAC_FLAG_CAPS_SET	0x0002
> @@ -3082,9 +3083,9 @@ int main(int argc, char *argv[])
>   			break;
>   		case 'p':
>   			if (optarg)
> -				imaevm_params.keypass = optarg;
> +				keypass = optarg;
>   			else
> -				imaevm_params.keypass = get_password();
> +				keypass = get_password();
>   			break;
>   		case 'f':
>   			sigfile = 1;
> @@ -3226,8 +3227,8 @@ int main(int argc, char *argv[])
>   		}
>   	}
>   
> -	if (!imaevm_params.keypass)
> -		imaevm_params.keypass = getenv("EVMCTL_KEY_PASSWORD");
> +	if (!keypass)
> +		keypass = getenv("EVMCTL_KEY_PASSWORD");
>   
>   	if (imaevm_params.keyfile != NULL &&
>   	    imaevm_params.eng == NULL &&


The problem at this point in evmctl is that keypass is never passed to 
anywhere. You have to pass it to sign_hash().

> diff --git a/src/libimaevm.c b/src/libimaevm.c
> index 18b6a6f27237..10ec847da08a 100644
> --- a/src/libimaevm.c
> +++ b/src/libimaevm.c
> @@ -1124,7 +1124,8 @@ static int get_hash_algo_v1(const char *algo)
>   }
>   
>   static int sign_hash_v1(const char *hashalgo, const unsigned char *hash,
> -			int size, const char *keyfile, unsigned char *sig)
> +			int size, const char *keyfile, const char *keypass,
> +			unsigned char *sig)
>   {
>   	int len = -1, hashalgo_idx;
>   	SHA_CTX ctx;
> @@ -1158,7 +1159,7 @@ static int sign_hash_v1(const char *hashalgo, const unsigned char *hash,
>   	log_info("hash(%s): ", hashalgo);
>   	log_dump(hash, size);
>   
> -	key = read_priv_key(keyfile, imaevm_params.keypass);
> +	key = read_priv_key(keyfile, keypass);
>   	if (!key)
>   		return -1;
>   
> @@ -1211,7 +1212,8 @@ out:
>    * Return: -1 signing error, >0 length of signature
>    */
>   static int sign_hash_v2(const char *algo, const unsigned char *hash,
> -			int size, const char *keyfile, unsigned char *sig)
> +			int size, const char *keyfile, const char *keypass,
> +			unsigned char *sig)
>   {
>   	struct signature_v2_hdr *hdr;
>   	int len = -1;
> @@ -1246,7 +1248,7 @@ static int sign_hash_v2(const char *algo, const unsigned char *hash,
>   	log_info("hash(%s): ", algo);
>   	log_dump(hash, size);
>   
> -	pkey = read_priv_pkey(keyfile, imaevm_params.keypass);
> +	pkey = read_priv_pkey(keyfile, keypass);
>   	if (!pkey)
>   		return -1;
>   
> @@ -1316,14 +1318,11 @@ err:
>   
>   int sign_hash(const char *hashalgo, const unsigned char *hash, int size, const char *keyfile, const char *keypass, unsigned char *sig)
>   {
> -	if (keypass)
> -		imaevm_params.keypass = keypass;
> -

I hope all library callers, other than evmctl, passed the keypass in 
already, otherwise they could have set the password via 
imaevm_params.keypass global and passed in NULL and for them this will 
be a behavioral change. Anyway, you have no other choice to get rid of 
imaevm_params as much as possible, so I guess it's ok.

It looks like at this point imaevm_params.keypass doesn't have a single 
user anymore so you could rename it to 'unused1' or so in the stucture 
since it will have zero effect for anyone to set it.

>   	if (imaevm_params.x509)
> -		return sign_hash_v2(hashalgo, hash, size, keyfile, sig);
> +		return sign_hash_v2(hashalgo, hash, size, keyfile, keypass, sig);
>   #if CONFIG_SIGV1
>   	else
> -		return sign_hash_v1(hashalgo, hash, size, keyfile, sig);
> +		return sign_hash_v1(hashalgo, hash, size, keyfile, keypass, sig);
>   #endif
>   	log_info("Signature version 1 deprecated.");
>   	return -1;