Re: [ima-evm-utils PATCH v2 11/13] Use a file specific hash algorithm variable for signing files

From: Stefan Berger <stefanb@linux.ibm.com>
To: Mimi Zohar <zohar@linux.ibm.com>, linux-integrity@vger.kernel.org
Subject: Re: [ima-evm-utils PATCH v2 11/13] Use a file specific hash algorithm variable for signing files
Date: Tue, 2 Jan 2024 08:42:13 -0500	[thread overview]
Message-ID: <70ce6c8e-308d-4473-90d1-b597d27b493c@linux.ibm.com> (raw)
In-Reply-To: <20231206192734.339999-12-zohar@linux.ibm.com>


On 12/6/23 14:27, 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.
> 
> Propagate using the file specific hash algorithm variable in sign_evm(),
> 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@linux.ibm.com>

Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>

> ---
>   src/evmctl.c | 34 +++++++++++++++++-----------------
>   1 file changed, 17 insertions(+), 17 deletions(-)
> 
> diff --git a/src/evmctl.c b/src/evmctl.c
> index 9e1f4e33bc01..8eb2c46fbff0 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 *g_hash_algo = DEFAULT_HASH_ALGO;
>   
>   #define HMAC_FLAG_NO_UUID	0x0001
>   #define HMAC_FLAG_CAPS_SET	0x0002
> @@ -564,18 +565,18 @@ out:
>   	return err;
>   }
>   
> -static int sign_evm(const char *file, const char *key)
> +static int sign_evm(const char *file, char *hash_algo, const char *key)
>   {
>   	unsigned char hash[MAX_DIGEST_SIZE];
>   	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(g_hash_algo);
>   
>   	if (algo < 0) {
> -		log_err("Unknown hash algo: %s\n", imaevm_params.hash_algo);
> +		log_err("Unknown hash algo: %s\n", g_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, g_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): ", g_hash_algo);
>   
>   	if (sigdump || imaevm_params.verbose >= LOG_INFO)
>   		imaevm_hexdump(hash, len);
> @@ -650,18 +651,18 @@ static int hash_ima(const char *file)
>   	return 0;
>   }
>   
> -static int sign_ima(const char *file, const char *key)
> +static int sign_ima(const char *file, char *hash_algo, const char *key)
>   {
>   	unsigned char hash[MAX_DIGEST_SIZE];
>   	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));
> @@ -751,7 +752,7 @@ static int sign_ima_file(const char *file)
>   
>   	key = imaevm_params.keyfile ? : "/etc/keys/privkey_evm.pem";
>   
> -	return sign_ima(file, key);
> +	return sign_ima(file, g_hash_algo, key);
>   }
>   
>   static int cmd_sign_ima(struct command *cmd)
> @@ -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(g_hash_algo, hash,
>   					   hashlen / 2, key, NULL, sig + 1);
>   			sig[0] = EVM_IMA_XATTR_DIGSIG;
>   		}
> @@ -874,7 +875,6 @@ static int cmd_sign_hash(struct command *cmd)
>   		print_usage(cmd);
>   		return -1;
>   	}
> -
>   	return 0;
>   }
>   
> @@ -886,7 +886,7 @@ static int sign_evm_path(const char *file)
>   	key = imaevm_params.keyfile ? : "/etc/keys/privkey_evm.pem";
>   
>   	if (digsig) {
> -		err = sign_ima(file, key);
> +		err = sign_ima(file, g_hash_algo, key);
>   		if (err)
>   			return err;
>   	}
> @@ -897,7 +897,7 @@ static int sign_evm_path(const char *file)
>   			return err;
>   	}
>   
> -	return sign_evm(file, key);
> +	return sign_evm(file, g_hash_algo, key);
>   }
>   
>   static int cmd_sign_evm(struct command *cmd)
> @@ -1426,7 +1426,7 @@ static int cmd_hmac_evm(struct command *cmd)
>   	key = imaevm_params.keyfile ? : "/etc/keys/privkey_evm.pem";
>   
>   	if (digsig) {
> -		err = sign_ima(file, key);
> +		err = sign_ima(file, g_hash_algo, key);
>   		if (err)
>   			return err;
>   	}
> @@ -3087,7 +3087,7 @@ int main(int argc, char *argv[])
>   			sigdump = 1;
>   			break;
>   		case 'a':
> -			imaevm_params.hash_algo = optarg;
> +			g_hash_algo = optarg;
>   			break;
>   		case 'p':
>   			if (optarg)