OSX/sec/Security/SecCFAllocator.c

   1 /*
   2  * Copyright (c) 2016 Apple Inc. All Rights Reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23
  24 #include <Security/SecCFAllocator.h>
  25 #include <CoreFoundation/CoreFoundation.h>
  26 #include <corecrypto/cc.h>
  27 #include <malloc/malloc.h>
  28
  29 static CFAllocatorContext sDefaultCtx;
  30
  31 static CFStringRef SecCFAllocatorCopyDescription(const void *info) {
  32     return CFSTR("Custom CFAllocator for sensitive data that zeroizes on deallocate");
  33 }
  34
  35 // primary goal of this allocator is to clear memory when it is deallocated
  36 static void SecCFAllocatorDeallocate(void *ptr, void *info) {
  37     if (!ptr) return;
  38     size_t sz = malloc_size(ptr);
  39     if(sz) cc_clear(sz, ptr);
  40
  41     sDefaultCtx.deallocate(ptr, info);
  42 }
  43
  44 CFAllocatorRef SecCFAllocatorZeroize(void) {
  45     static dispatch_once_t sOnce = 0;
  46     static CFAllocatorRef sAllocator = NULL;
  47     dispatch_once(&sOnce, ^{
  48         CFAllocatorGetContext(kCFAllocatorMallocZone, &sDefaultCtx);
  49
  50         CFAllocatorContext ctx = {0,
  51             sDefaultCtx.info,
  52             sDefaultCtx.retain,
  53             sDefaultCtx.release,
  54             SecCFAllocatorCopyDescription,
  55             sDefaultCtx.allocate,
  56             sDefaultCtx.reallocate,
  57             SecCFAllocatorDeallocate,
  58             sDefaultCtx.preferredSize};
  59
  60         sAllocator = CFAllocatorCreate(NULL, &ctx);
  61     });
  62
  63     return sAllocator;
  64 }