[PATCH v2 1/2] integrity: Refactor asymmetric_verify for reusability

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

Refactor asymmetric_verify for reusability. Have it call
asymmetric_verify_common with the signature verification key and the
public_key structure as parameters. sigv3 support for ML-DSA will need to
check the public key type first to decide how to do the signature
verification and therefore will have these parameters available for
calling asymmetric_verify_common.

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
---
 security/integrity/digsig_asymmetric.c | 42 +++++++++++++++++---------
 1 file changed, 28 insertions(+), 14 deletions(-)

diff --git a/security/integrity/digsig_asymmetric.c b/security/integrity/digsig_asymmetric.c
index 6e68ec3becbd..e29ed73f15cd 100644
--- a/security/integrity/digsig_asymmetric.c
+++ b/security/integrity/digsig_asymmetric.c
@@ -79,18 +79,15 @@ static struct key *request_asymmetric_key(struct key *keyring, uint32_t keyid)
 	return key;
 }
 
-int asymmetric_verify(struct key *keyring, const char *sig,
-		      int siglen, const char *data, int datalen)
+static int asymmetric_verify_common(const struct key *key,
+				    const struct public_key *pk,
+				    const char *sig, int siglen,
+				    const char *data, int datalen)
 {
-	struct public_key_signature pks;
 	struct signature_v2_hdr *hdr = (struct signature_v2_hdr *)sig;
-	const struct public_key *pk;
-	struct key *key;
+	struct public_key_signature pks;
 	int ret;
 
-	if (siglen <= sizeof(*hdr))
-		return -EBADMSG;
-
 	siglen -= sizeof(*hdr);
 
 	if (siglen != be16_to_cpu(hdr->sig_size))
@@ -99,15 +96,10 @@ int asymmetric_verify(struct key *keyring, const char *sig,
 	if (hdr->hash_algo >= HASH_ALGO__LAST)
 		return -ENOPKG;
 
-	key = request_asymmetric_key(keyring, be32_to_cpu(hdr->keyid));
-	if (IS_ERR(key))
-		return PTR_ERR(key);
-
 	memset(&pks, 0, sizeof(pks));
 
 	pks.hash_algo = hash_algo_name[hdr->hash_algo];
 
-	pk = asymmetric_key_public_key(key);
 	pks.pkey_algo = pk->pkey_algo;
 	if (!strcmp(pk->pkey_algo, "rsa")) {
 		pks.encoding = "pkcs1";
@@ -127,11 +119,33 @@ int asymmetric_verify(struct key *keyring, const char *sig,
 	pks.s_size = siglen;
 	ret = verify_signature(key, &pks);
 out:
-	key_put(key);
 	pr_debug("%s() = %d\n", __func__, ret);
 	return ret;
 }
 
+int asymmetric_verify(struct key *keyring, const char *sig,
+		      int siglen, const char *data, int datalen)
+{
+	struct signature_v2_hdr *hdr = (struct signature_v2_hdr *)sig;
+	const struct public_key *pk;
+	struct key *key;
+	int ret;
+
+	if (siglen <= sizeof(*hdr))
+		return -EBADMSG;
+
+	key = request_asymmetric_key(keyring, be32_to_cpu(hdr->keyid));
+	if (IS_ERR(key))
+		return PTR_ERR(key);
+	pk = asymmetric_key_public_key(key);
+
+	ret = asymmetric_verify_common(key, pk, sig, siglen, data, datalen);
+
+	key_put(key);
+
+	return ret;
+}
+
 /*
  * calc_file_id_hash - calculate the hash of the ima_file_id struct data
  * @type: xattr type [enum evm_ima_xattr_type]
-- 
2.53.0