integrity: Asymmetric digsig supports SM2-with-SM3 algorithm

Asymmetric digsig supports SM2-with-SM3 algorithm combination,
so that IMA can also verify SM2's signature data.

Signed-off-by: Tianjia Zhang <[e-mail]>
Tested-by: Xufeng Zhang <[e-mail]>
Reviewed-by: Mimi Zohar <[e-mail]>
Reviewed-by: Vitaly Chikunov <[e-mail]>
Signed-off-by: Herbert Xu <[e-mail]>

security/integrity/digsig_asymmetric.c

···
 	memset(&pks, 0, sizeof(pks));
 
 	pks.hash_algo = hash_algo_name[hdr->hash_algo];
-	if (hdr->hash_algo == HASH_ALGO_STREEBOG_256 ||
-	    hdr->hash_algo == HASH_ALGO_STREEBOG_512) {
+	switch (hdr->hash_algo) {
+	case HASH_ALGO_STREEBOG_256:
+	case HASH_ALGO_STREEBOG_512:
 		/* EC-RDSA and Streebog should go together. */
 		pks.pkey_algo = "ecrdsa";
 		pks.encoding = "raw";
-	} else {
+		break;
+	case HASH_ALGO_SM3_256:
+		/* SM2 and SM3 should go together. */
+		pks.pkey_algo = "sm2";
+		pks.encoding = "raw";
+		break;
+	default:
 		pks.pkey_algo = "rsa";
 		pks.encoding = "pkcs1";
+		break;
 	}
 	pks.digest = (u8 *)data;
 	pks.digest_size = datalen;