Make CKM_AES_GCM usable.

mozilla/security/nss/lib/freebl/rijndael.c

Index: mozilla/security/nss/lib/freebl/rijndael.c
===================================================================
--- mozilla/security/nss/lib/freebl/rijndael.c	(revision 182578)
+++ mozilla/security/nss/lib/freebl/rijndael.c	(working copy)
@@ -1221,7 +1221,7 @@
 {
     int blocksize;
     /* Check args */
-    if (cx == NULL || output == NULL || input == NULL) {
+    if (cx == NULL || output == NULL || (input == NULL && inputLen != 0)) {

[wtc, 2013/03/26 18:24:46]

These changes allow an empty input to be represented as
input=NULL inputLen=0.  This allows us to call the default
StringPiece constructor and pass string_piece.data(),
string_piece.size() as input and inputLen.

[Ryan Sleevi, 2013/03/26 18:39:14]

I checked the PKCS#11 2.30 specs, and this seems valid according to Section 11.8
and notes from 11.1/11.2, and nothing from 6.11 conflicts, but it might be worth
double checking with Bob just to make sure there's not any assumptions here
about |input| being a valid pointer even when inputLen == 0 (eg: if there's some
assumption like that spelled out for memcpy in the C spec, where pointers must
be valid even when len == 0)

 	PORT_SetError(SEC_ERROR_INVALID_ARGS);
 	return SECFailure;
     }
@@ -1252,7 +1252,7 @@
 {
     int blocksize;
     /* Check args */
-    if (cx == NULL || output == NULL || input == NULL) {
+    if (cx == NULL || output == NULL || (input == NULL && inputLen != 0)) {
 	PORT_SetError(SEC_ERROR_INVALID_ARGS);
 	return SECFailure;
     }