[PATCH v4 2/3] x509: Detect sm2 keys by their parameters OID

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

From: Stefan Berger <stefanb@linux.ibm.com>

Detect whether a key is an sm2 type of key by its OID in the parameters
array rather than assuming that everything under OID_id_ecPublicKey
is sm2, which is not the case.

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Cc: David Howells <dhowells@redhat.com>
Cc: keyrings@vger.kernel.org
---
 crypto/asymmetric_keys/x509_cert_parser.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/crypto/asymmetric_keys/x509_cert_parser.c b/crypto/asymmetric_keys/x509_cert_parser.c
index 52c9b455fc7d..4643fe5ed69a 100644
--- a/crypto/asymmetric_keys/x509_cert_parser.c
+++ b/crypto/asymmetric_keys/x509_cert_parser.c
@@ -459,6 +459,7 @@ int x509_extract_key_data(void *context, size_t hdrlen,
 			  const void *value, size_t vlen)
 {
 	struct x509_parse_context *ctx = context;
+	enum OID oid;
 
 	ctx->key_algo = ctx->last_oid;
 	switch (ctx->last_oid) {
@@ -470,7 +471,17 @@ int x509_extract_key_data(void *context, size_t hdrlen,
 		ctx->cert->pub->pkey_algo = "ecrdsa";
 		break;
 	case OID_id_ecPublicKey:
-		ctx->cert->pub->pkey_algo = "sm2";
+		if (ctx->params_size < 2)
+			return -ENOPKG;
+
+		oid = look_up_OID(ctx->params + 2, ctx->params_size - 2);
+		switch (oid) {
+		case OID_sm2:
+			ctx->cert->pub->pkey_algo = "sm2";
+			break;
+		default:
+			return -ENOPKG;
+		}
 		break;
 	default:
 		return -ENOPKG;
-- 
2.26.2