libsecurity_transform/lib/SecMaskGenerationFunctionTransform.c

   1 //
   2 //  SecMaskGenerationFunctionTransform.c
   3 //  libsecurity_transform
   4 //
   5 //  Created by Josh Osborne on 10/6/11.
   6 //  Copyright 2011 Apple. All rights reserved.
   7 //
   8
   9 #include <stdio.h>
  10 #include <CoreFoundation/CoreFoundation.h>
  11 #include "SecMaskGenerationFunctionTransform.h"
  12 #include "SecCustomTransform.h"
  13 #include "SecDigestTransform.h"
  14 #include "misc.h"
  15 #include "Utilities.h"
  16
  17 static const CFStringRef kMaskGenerationFunctionTransformName = CFSTR("com.apple.security.MGF1");
  18 static const CFStringRef kLengthName = CFSTR("Length");
  19
  20 static SecTransformInstanceBlock MaskGenerationFunctionTransform(CFStringRef name,
  21                                                   SecTransformRef newTransform,
  22                                                   SecTransformImplementationRef ref)
  23 {
  24     __block CFMutableDataRef accumulator = CFDataCreateMutable(NULL, 0);
  25     __block int32_t outputLength = 0;
  26
  27     SecTransformInstanceBlock instanceBlock = ^{
  28         SecTransformSetTransformAction(ref, kSecTransformActionFinalize, ^{
  29             CFRelease(accumulator);
  30
  31             return (CFTypeRef)NULL;
  32         });
  33
  34         // XXX: be a good citizen, put a validator in for the types.
  35
  36         SecTransformSetAttributeAction(ref, kSecTransformActionAttributeNotification, kLengthName, ^CFTypeRef(SecTransformAttributeRef attribute, CFTypeRef value) {
  37             CFNumberGetValue((CFNumberRef)value, kCFNumberSInt32Type, &outputLength);
  38             if (outputLength <= 0) {
  39                 SecTransformCustomSetAttribute(ref, kSecTransformAbortAttributeName, kSecTransformMetaAttributeValue, CreateSecTransformErrorRef(kSecTransformErrorInvalidLength, "MaskGenerationFunction Length must be one or more (not %@)", value));
  40             }
  41
  42             return (CFTypeRef)NULL;
  43         });
  44
  45         SecTransformSetAttributeAction(ref, kSecTransformActionAttributeNotification, kSecTransformInputAttributeName, ^CFTypeRef(SecTransformAttributeRef attribute, CFTypeRef value) {
  46             if (value) {
  47                 CFDataRef d = value;
  48                 CFDataAppendBytes(accumulator, CFDataGetBytePtr(d), CFDataGetLength(d));
  49             } else {
  50                 int32_t i = 0, l = 0;
  51                 (void)transforms_assume(outputLength > 0);
  52                 CFStringRef digestType = SecTranformCustomGetAttribute(ref, kSecDigestTypeAttribute, kSecTransformMetaAttributeValue);
  53                 SecTransformRef digest0 = transforms_assume(SecDigestTransformCreate(digestType, 0, NULL));
  54                 int32_t digestLength = 0;
  55                 {
  56                     CFNumberRef digestLengthAsCFNumber = SecTransformGetAttribute(digest0, kSecDigestLengthAttribute);
  57                     CFNumberGetValue(transforms_assume(digestLengthAsCFNumber), kCFNumberSInt32Type, &digestLength);
  58                 }
  59                 (void)transforms_assume(digestLength >= 0);
  60
  61                 UInt8 *buffer = malloc(outputLength + digestLength);
  62                 if (!buffer) {
  63                     SecTransformCustomSetAttribute(ref, kSecTransformAbortAttributeName, kSecTransformMetaAttributeValue, GetNoMemoryErrorAndRetain());
  64                     return (CFErrorRef)NULL;
  65                 }
  66
  67                 dispatch_group_t all_hashed = dispatch_group_create();
  68                 dispatch_group_enter(all_hashed);
  69                 for(; l < outputLength; l += digestLength, i++) {
  70                     dispatch_group_enter(all_hashed);
  71                     CFErrorRef err = NULL;
  72                     SecTransformRef digest = NULL;
  73                     if (l == 0) {
  74                         digest = digest0;
  75                     } else {
  76                         digest = SecDigestTransformCreate(digestType, 0, &err);
  77                         if (digest == NULL) {
  78                             SecTransformCustomSetAttribute(ref, kSecTransformAbortAttributeName, kSecTransformMetaAttributeValue, err);
  79                             return (CFErrorRef)NULL;
  80                         }
  81                     }
  82
  83                     // NOTE: we shuld be able to do this without the copy, make a transform that takes an
  84                     // array and outputs each item in the array followed by a NULL ought to be quicker.
  85                     CFMutableDataRef accumulatorPlusCounter = CFDataCreateMutableCopy(NULL, CFDataGetLength(accumulator) + sizeof(uint32_t), accumulator);
  86                     int32_t bigendian_i = htonl(i);
  87                     CFDataAppendBytes(accumulatorPlusCounter, (UInt8*)&bigendian_i, sizeof(bigendian_i));
  88                     SecTransformSetAttribute(digest, kSecTransformInputAttributeName, accumulatorPlusCounter, &err);
  89                     CFRelease(accumulatorPlusCounter);
  90
  91                     UInt8 *buf = buffer + l;
  92                     SecTransformExecuteAsync(digest, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^(CFTypeRef message, CFErrorRef error, Boolean isFinal) {
  93                         if (message) {
  94                             CFIndex messageLen = CFDataGetLength(message);
  95                             CFDataGetBytes(message, CFRangeMake(0, messageLen), buf);
  96                         }
  97                         if (error) {
  98                             SecTransformCustomSetAttribute(ref, kSecTransformAbortAttributeName, kSecTransformMetaAttributeValue, error);
  99                         }
 100                         if (isFinal) {
 101                             dispatch_group_leave(all_hashed);
 102                         }
 103                     });
 104                     CFRelease(digest);
 105                 }
 106
 107                 dispatch_group_leave(all_hashed);
 108                 dispatch_group_wait(all_hashed, DISPATCH_TIME_FOREVER);
 109                 CFDataRef out = CFDataCreateWithBytesNoCopy(NULL, buffer, outputLength, kCFAllocatorMalloc);
 110                 SecTransformCustomSetAttribute(ref, kSecTransformOutputAttributeName, kSecTransformMetaAttributeValue, out);
 111                 CFRelease(out);
 112                 SecTransformCustomSetAttribute(ref, kSecTransformOutputAttributeName, kSecTransformMetaAttributeValue, NULL);
 113             }
 114             return (CFErrorRef)NULL;
 115         });
 116
 117         return (CFErrorRef)NULL;
 118     };
 119
 120     return Block_copy(instanceBlock);
 121 }
 122
 123 SecTransformRef SecCreateMaskGenerationFunctionTransform(CFStringRef hashType, int length, CFErrorRef *error)
 124 {
 125     static dispatch_once_t once;
 126         __block Boolean ok = TRUE;
 127
 128     if (length <= 0) {
 129         if (error) {
 130             *error = CreateSecTransformErrorRef(kSecTransformErrorInvalidLength, "MaskGenerationFunction Length must be one or more (not %d)", length);
 131         }
 132         return NULL;
 133     }
 134
 135     dispatch_once(&once, ^(void) {
 136         ok = SecTransformRegister(kMaskGenerationFunctionTransformName, MaskGenerationFunctionTransform, error);
 137     });
 138
 139     if (!ok) {
 140         return NULL;
 141     }
 142
 143     SecTransformRef ret = SecTransformCreate(kMaskGenerationFunctionTransformName, error);
 144     if (!ret) {
 145         return NULL;
 146     }
 147
 148     if (!SecTransformSetAttribute(ret, kSecDigestTypeAttribute, hashType ? hashType : kSecDigestSHA1, error)) {
 149         CFRelease(ret);
 150         return NULL;
 151     }
 152
 153     CFNumberRef len = CFNumberCreate(NULL, kCFNumberIntType, &length);
 154     ok = SecTransformSetAttribute(ret, kLengthName, len, error);
 155     CFRelease(len);
 156     if (!ok) {
 157         CFRelease(ret);
 158         return NULL;
 159     }
 160
 161     return ret;
 162 }