[PATCH 1/2] ima-evm-utils: Do not allow fallback and unknown hash algos

[Vitaly Chikunov <vt@xxxxxxxxxxxx>]

Falling back and permissiveness could have security implications.

Signed-off-by: Vitaly Chikunov <vt@xxxxxxxxxxxx>
---
 src/evmctl.c    | 4 ++++
 src/libimaevm.c | 7 +++++--
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/src/evmctl.c b/src/evmctl.c
index 3289061..3766343 100644
--- a/src/evmctl.c
+++ b/src/evmctl.c
@@ -584,6 +584,10 @@ static int hash_ima(const char *file)
 	int len, err, offset;
 	int algo = get_hash_algo(params.hash_algo);
 
+	if (algo < 0) {
+		log_err("Unknown hash algo: %s\n", params.hash_algo);
+		return -1;
+	}
 	if (algo > PKEY_HASH_SHA1) {
 		hash[0] = IMA_XATTR_DIGEST_NG;
 		hash[1] = algo;
diff --git a/src/libimaevm.c b/src/libimaevm.c
index 2d99570..86c5784 100644
--- a/src/libimaevm.c
+++ b/src/libimaevm.c
@@ -571,8 +571,7 @@ int get_hash_algo(const char *algo)
 		    !strcmp(algo, hash_algo_name[i]))
 			return i;
 
-	log_info("digest %s not found, fall back to sha1\n", algo);
-	return PKEY_HASH_SHA1;
+	return -1;
 }
 
 static int get_hash_algo_from_sig(unsigned char *sig)
@@ -920,6 +919,10 @@ int sign_hash_v2(const char *algo, const unsigned char *hash, int size, const ch
 	hdr->version = (uint8_t) DIGSIG_VERSION_2;
 
 	hdr->hash_algo = get_hash_algo(algo);
+	if (hdr->hash_algo == -1) {
+		log_err("sign_hash_v2: hash algo is unknown: %s\n", algo);
+		return -1;
+	}
 
 	calc_keyid_v2(&keyid, name, pkey);
 	hdr->keyid = keyid;
-- 
2.11.0