KEYS: Store public key algo ID in public_key struct

Store public key algo ID in public_key struct for reference purposes.  This
allows it to be removed from the x509_certificate struct and used to find a
default in public_key_verify_signature().

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Josh Boyer <jwboyer@redhat.com>

crypto/asymmetric_keys/x509_cert_parser.c

@@ -343,8 +343,9 @@ int x509_extract_key_data(void *context, size_t hdrlen,
 	if (ctx->last_oid != OID_rsaEncryption)
 		return -ENOPKG;
 
-	/* There seems to be an extraneous 0 byte on the front of the data */
-	ctx->cert->pkey_algo = PKEY_ALGO_RSA;
+	ctx->cert->pub->pkey_algo = PKEY_ALGO_RSA;
+
+	/* Discard the BIT STRING metadata */
 	ctx->key = value + 1;
 	ctx->key_size = vlen - 1;
 	return 0;

crypto/asymmetric_keys/x509_parser.h

@@ -20,7 +20,6 @@ struct x509_certificate {
 	char		*authority;		/* Authority key fingerprint as hex */
 	struct tm	valid_from;
 	struct tm	valid_to;
-	enum pkey_algo	pkey_algo : 8;		/* Public key algorithm */
 	enum pkey_algo	sig_pkey_algo : 8;	/* Signature public key algorithm */
 	enum pkey_hash_algo sig_hash_algo : 8;	/* Signature hash algorithm */
 	const void	*tbs;			/* Signed data */

crypto/asymmetric_keys/x509_public_key.c

@@ -108,7 +108,7 @@ static int x509_key_preparse(struct key_preparsed_payload *prep)
 
 	pr_devel("Cert Issuer: %s\n", cert->issuer);
 	pr_devel("Cert Subject: %s\n", cert->subject);
-	pr_devel("Cert Key Algo: %s\n", pkey_algo_name[cert->pkey_algo]);
+	pr_devel("Cert Key Algo: %s\n", pkey_algo_name[cert->pub->pkey_algo]);
 	pr_devel("Cert Valid From: %04ld-%02d-%02d %02d:%02d:%02d\n",
 		 cert->valid_from.tm_year + 1900, cert->valid_from.tm_mon + 1,
 		 cert->valid_from.tm_mday, cert->valid_from.tm_hour,
@@ -165,7 +165,7 @@ static int x509_key_preparse(struct key_preparsed_payload *prep)
 		goto error_free_cert;
 	}
 
-	cert->pub->algo = pkey_algo[cert->pkey_algo];
+	cert->pub->algo = pkey_algo[cert->pub->pkey_algo];
 	cert->pub->id_type = PKEY_ID_X509;
 
 	/* Check the signature on the key */