KEYS: Generalise system_verify_data() to provide access to internal content

Generalise system_verify_data() to provide access to internal content
through a callback.  This allows all the PKCS#7 stuff to be hidden inside
this function and removed from the PE file parser and the PKCS#7 test key.

If external content is not required, NULL should be passed as data to the
function.  If the callback is not required, that can be set to NULL.

The function is now called verify_pkcs7_signature() to contrast with
verify_pefile_signature() and the definitions of both have been moved into
linux/verification.h along with the key_being_used_for enum.

Signed-off-by: David Howells <dhowells@redhat.com>

1 files changed, 11 insertions, 10 deletions

diff --git a/crypto/asymmetric_keys/pkcs7_parser.c b/crypto/asymmetric_keys/pkcs7_parser.c
index 835701613125..af4cd8649117 100644
--- a/crypto/asymmetric_keys/pkcs7_parser.c
+++ b/crypto/asymmetric_keys/pkcs7_parser.c
@@ -168,24 +168,25 @@ EXPORT_SYMBOL_GPL(pkcs7_parse_message);
  * @pkcs7: The preparsed PKCS#7 message to access
  * @_data: Place to return a pointer to the data
  * @_data_len: Place to return the data length
- * @want_wrapper: True if the ASN.1 object header should be included in the data
+ * @_headerlen: Size of ASN.1 header not included in _data
  *
- * Get access to the data content of the PKCS#7 message, including, optionally,
- * the header of the ASN.1 object that contains it.  Returns -ENODATA if the
- * data object was missing from the message.
+ * Get access to the data content of the PKCS#7 message.  The size of the
+ * header of the ASN.1 object that contains it is also provided and can be used
+ * to adjust *_data and *_data_len to get the entire object.
+ *
+ * Returns -ENODATA if the data object was missing from the message.
  */
 int pkcs7_get_content_data(const struct pkcs7_message *pkcs7,
 			   const void **_data, size_t *_data_len,
-			   bool want_wrapper)
+			   size_t *_headerlen)
 {
-	size_t wrapper;
-
 	if (!pkcs7->data)
 		return -ENODATA;
 
-	wrapper = want_wrapper ? pkcs7->data_hdrlen : 0;
-	*_data = pkcs7->data - wrapper;
-	*_data_len = pkcs7->data_len + wrapper;
+	*_data = pkcs7->data;
+	*_data_len = pkcs7->data_len;
+	if (_headerlen)
+		*_headerlen = pkcs7->data_hdrlen;
 	return 0;
 }
 EXPORT_SYMBOL_GPL(pkcs7_get_content_data);