Re: [ima-evm-utils PATCH 10/12] Update EVM signature verification to use a local hash algorithm variable

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On 11/19/23 11:50, Mimi Zohar wrote:
Instead of relying on the "imaevm_params.algo" global variable, which
is not concurrency-safe, define and use a local file hash algorithm
variable.

Update calc_evm_hash(), verify_hash2().

Signed-off-by: Mimi Zohar <zohar@xxxxxxxxxxxxx>
---
  src/evmctl.c | 19 ++++++++++---------
  1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/src/evmctl.c b/src/evmctl.c
index ad4565b3ee52..7ae897d8b8b3 100644
--- a/src/evmctl.c
+++ b/src/evmctl.c
@@ -340,7 +340,8 @@ err:
   * Returns 0 for EVP_ function failures. Return -1 for other failures.
   * Return hash algorithm size on success.
   */
-static int calc_evm_hash(const char *file, unsigned char *hash)
+static int calc_evm_hash(const char *file, const char *hash_algo,
+			 unsigned char *hash)
  {
          const EVP_MD *md;
  	struct stat st;
@@ -408,10 +409,9 @@ static int calc_evm_hash(const char *file, unsigned char *hash)
  	}
  #endif
- md = EVP_get_digestbyname(imaevm_params.hash_algo);
+	md = EVP_get_digestbyname(hash_algo);
  	if (!md) {
-		log_err("EVP_get_digestbyname(%s) failed\n",
-			imaevm_params.hash_algo);
+		log_err("EVP_get_digestbyname(%s) failed\n", hash_algo);
  		err = 0;
  		goto out;
  	}
@@ -570,7 +570,7 @@ static int sign_evm(const char *file, const char *key)
  	unsigned char sig[MAX_SIGNATURE_SIZE];
  	int len, err;
- len = calc_evm_hash(file, hash);
+	len = calc_evm_hash(file, imaevm_params.hash_algo, hash);
  	if (len <= 1)
  		return len;
  	assert(len <= sizeof(hash));
@@ -909,6 +909,7 @@ static int verify_evm(void *public_keys, const char *file)
  {
  	unsigned char hash[MAX_DIGEST_SIZE];
  	unsigned char sig[MAX_SIGNATURE_SIZE];
+	const char *hash_algo = NULL;
  	int sig_hash_algo;
  	int mdlen;
  	int len;
@@ -938,15 +939,15 @@ static int verify_evm(void *public_keys, const char *file)
  		log_err("unknown hash algo: %s\n", file);
  		return -1;
  	}
-	imaevm_params.hash_algo = imaevm_hash_algo_by_id(sig_hash_algo);
+	hash_algo = imaevm_hash_algo_by_id(sig_hash_algo);
- mdlen = calc_evm_hash(file, hash);
+	mdlen = calc_evm_hash(file, hash_algo, hash);
  	if (mdlen <= 1)
  		return mdlen;
  	assert(mdlen <= sizeof(hash));
- return verify_hash2(public_keys, file, imaevm_params.hash_algo,
-			    hash, mdlen, sig, len);
+	return verify_hash2(public_keys, file, hash_algo, hash,
+			    mdlen, sig, len);
  }
static int cmd_verify_evm(struct command *cmd)

Reviewed-by: Stefan Berger <stefanb@xxxxxxxxxxxxx>




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