Re: [ima-evm-utils PATCH 11/12] Use a file specific hash algorithm variable for signing files

[Stefan Berger <stefanb@xxxxxxxxxxxxx>]

On 11/19/23 11:50, Mimi Zohar wrote:
> Instead of relying on the library "imaevm_params.algo" global variable,
> which is not concurrency-safe, define and use an evmctl file specific
> hash algorithm variable.
>
> Propogate using the file specific hash algorithm variable in sign_evm(),

-> Propagate

> sign_ima(), hash_ima(), and sign_hash() function.
>
> Replace using the library function ima_calc_hash() with ima_calc_hash2().
>
> Signed-off-by: Mimi Zohar <zohar@xxxxxxxxxxxxx>
> ---
>   src/evmctl.c | 21 +++++++++++----------
>   1 file changed, 11 insertions(+), 10 deletions(-)
>
> diff --git a/src/evmctl.c b/src/evmctl.c
> index 7ae897d8b8b3..b802eeb1bf15 100644
> --- a/src/evmctl.c
> +++ b/src/evmctl.c
> @@ -140,6 +140,7 @@ static bool evm_immutable;
>   static bool evm_portable;
>   static bool veritysig;
>   static bool hwtpm;
> +static char *hash_algo;

g_hash_algo to avoid shadowing this variable in some cases where there 
is a function parameter of the same name?


>   
>   #define HMAC_FLAG_NO_UUID	0x0001
>   #define HMAC_FLAG_CAPS_SET	0x0002
> @@ -570,12 +571,12 @@ static int sign_evm(const char *file, const char *key)

Add hash_algo to the parameters here and call it sign_evm(file, key, 
g_hash_algo)? It makes sense to pass the hash_algo into this function 
that needs to know this for the signature and pushed the usage of global 
variables further out.

>   	unsigned char sig[MAX_SIGNATURE_SIZE];
>   	int len, err;
>   
> -	len = calc_evm_hash(file, imaevm_params.hash_algo, hash);
> +	len = calc_evm_hash(file, hash_algo, hash);
>   	if (len <= 1)
>   		return len;
>   	assert(len <= sizeof(hash));
>   
> -	len = sign_hash(imaevm_params.hash_algo, hash, len, key, NULL, sig + 1);
> +	len = sign_hash(hash_algo, hash, len, key, NULL, sig + 1);
>   	if (len <= 1)
>   		return len;
>   	assert(len < sizeof(sig));
> @@ -609,10 +610,10 @@ static int hash_ima(const char *file)
>   {
>   	unsigned char hash[MAX_DIGEST_SIZE + 2]; /* +2 byte xattr header */
>   	int len, err, offset;
> -	int algo = imaevm_get_hash_algo(imaevm_params.hash_algo);
> +	int algo = imaevm_get_hash_algo(hash_algo);
>   
>   	if (algo < 0) {
> -		log_err("Unknown hash algo: %s\n", imaevm_params.hash_algo);
> +		log_err("Unknown hash algo: %s\n", hash_algo);
>   		return -1;
>   	}
>   	if (algo > PKEY_HASH_SHA1) {
> @@ -624,7 +625,7 @@ static int hash_ima(const char *file)
>   		offset = 1;
>   	}
>   
> -	len = ima_calc_hash(file, hash + offset);
> +	len = ima_calc_hash2(file, hash_algo, hash + offset);
>   	if (len <= 1)
>   		return len;
>   	assert(len + offset <= sizeof(hash));
> @@ -632,7 +633,7 @@ static int hash_ima(const char *file)
>   	len += offset;
>   
>   	if (imaevm_params.verbose >= LOG_INFO)
> -		log_info("hash(%s): ", imaevm_params.hash_algo);
> +		log_info("hash(%s): ", hash_algo);
>   
>   	if (sigdump || imaevm_params.verbose >= LOG_INFO)
>   		imaevm_hexdump(hash, len);
> @@ -656,12 +657,12 @@ static int sign_ima(const char *file, const char *key)
>   	unsigned char sig[MAX_SIGNATURE_SIZE];
>   	int len, err;
>   
> -	len = ima_calc_hash(file, hash);
> +	len = ima_calc_hash2(file, hash_algo, hash);
>   	if (len <= 1)
>   		return len;
>   	assert(len <= sizeof(hash));
>   
> -	len = sign_hash(imaevm_params.hash_algo, hash, len, key, NULL, sig + 1);
> +	len = sign_hash(hash_algo, hash, len, key, NULL, sig + 1);
>   	if (len <= 1)
>   		return len;
>   	assert(len < sizeof(sig));
> @@ -854,7 +855,7 @@ static int cmd_sign_hash(struct command *cmd)
>   			assert(hashlen / 2 <= sizeof(hash));
>   			hex2bin(hash, line, hashlen / 2);
>   
> -			siglen = sign_hash(imaevm_params.hash_algo, hash,
> +			siglen = sign_hash(hash_algo, hash,
>   					   hashlen / 2, key, NULL, sig + 1);
>   			sig[0] = EVM_IMA_XATTR_DIGSIG;
>   		}
> @@ -3077,7 +3078,7 @@ int main(int argc, char *argv[])
>   			sigdump = 1;
>   			break;
>   		case 'a':
> -			imaevm_params.hash_algo = optarg;
> +			hash_algo = optarg;
>   			break;
>   		case 'p':
>   			if (optarg)