Make CKM_AES_GCM usable.

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

 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 /* $Id: rijndael.c,v 1.30 2013/01/25 18:02:53 rrelyea%redhat.com Exp $ */
 
 #ifdef FREEBL_NO_DEPEND
 #include "stubs.h"
 #endif
 
 #include "prinit.h"
@@ skipping 1203 matching lines @@
  * Encrypt an arbitrary-length buffer.  The output buffer must already be
  * allocated to at least inputLen.
  */
 SECStatus 
 AES_Encrypt(AESContext *cx, unsigned char *output,
             unsigned int *outputLen, unsigned int maxOutputLen,
             const unsigned char *input, unsigned int inputLen)
 {
     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;
     }
     blocksize = 4 * cx->Nb;
     if (cx->isBlock && (inputLen % blocksize != 0)) {
         PORT_SetError(SEC_ERROR_INPUT_LEN);
         return SECFailure;
     }
     if (maxOutputLen < inputLen) {
         PORT_SetError(SEC_ERROR_OUTPUT_LEN);
@@ skipping 10 matching lines @@
  * Decrypt and arbitrary-length buffer.  The output buffer must already be
  * allocated to at least inputLen.
  */
 SECStatus 
 AES_Decrypt(AESContext *cx, unsigned char *output,
             unsigned int *outputLen, unsigned int maxOutputLen,
             const unsigned char *input, unsigned int inputLen)
 {
     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;
     }
     blocksize = 4 * cx->Nb;
     if (cx->isBlock && (inputLen % blocksize != 0)) {
         PORT_SetError(SEC_ERROR_INPUT_LEN);
         return SECFailure;
     }
     if (maxOutputLen < inputLen) {
         PORT_SetError(SEC_ERROR_OUTPUT_LEN);
         return SECFailure;
     }
     *outputLen = inputLen;
     return (*cx->worker)(cx->worker_cx, output, outputLen, maxOutputLen,        
                              input, inputLen, blocksize);
 }