OSX/sec/SOSCircle/SecureObjectSync/SOSInternal.c

   1 /*
   2  * Copyright (c) 2012-2014 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
  25 #include <Security/SecureObjectSync/SOSInternal.h>
  26 #include <Security/SecureObjectSync/SOSCircle.h>
  27 #include <Security/SecureObjectSync/SOSCloudCircle.h>
  28 #include <Security/SecureObjectSync/SOSKVSKeys.h>
  29 #include "utilities/SecCFError.h"
  30 #include "utilities/SecCFRelease.h"
  31 #include "utilities/SecCFWrappers.h"
  32 #include "utilities/iOSforOSX.h"
  33
  34 #include <CoreFoundation/CoreFoundation.h>
  35
  36 #include <Security/SecKey.h>
  37 #include <Security/SecKeyPriv.h>
  38 #include <Security/SecItem.h>
  39 #include <securityd/SecDbItem.h> // For SecError
  40 #include "utilities/iOSforOSX.h"
  41
  42 #include <Security/SecBase64.h>
  43 #include <utilities/der_plist.h>
  44 #include <utilities/der_plist_internal.h>
  45 #include <corecrypto/ccder.h>
  46 #include <utilities/der_date.h>
  47
  48 #include <corecrypto/ccrng.h>
  49 #include <corecrypto/ccrng_pbkdf2_prng.h>
  50
  51 #include <CommonCrypto/CommonRandomSPI.h>
  52
  53 #include <AssertMacros.h>
  54
  55 CFStringRef kSOSErrorDomain = CFSTR("com.apple.security.sos.error");
  56
  57 bool SOSErrorCreate(CFIndex errorCode, CFErrorRef *error, CFDictionaryRef formatOptions, CFStringRef format, ...) {
  58     if (!errorCode) return true;
  59     if (error && !*error) {
  60         va_list va;
  61         va_start(va, format);
  62         SecCFCreateErrorWithFormatAndArguments(errorCode, kSOSErrorDomain, NULL, error, formatOptions, format, va);
  63         va_end(va);
  64     }
  65     return false;
  66 }
  67
  68 bool SOSCreateError(CFIndex errorCode, CFStringRef descriptionString, CFErrorRef previousError, CFErrorRef *newError) {
  69     SOSCreateErrorWithFormat(errorCode, previousError, newError, NULL, CFSTR("%@"), descriptionString);
  70     return true;
  71 }
  72
  73 bool SOSCreateErrorWithFormat(CFIndex errorCode, CFErrorRef previousError, CFErrorRef *newError,
  74                               CFDictionaryRef formatOptions, CFStringRef format, ...) {
  75     va_list va;
  76     va_start(va, format);
  77     bool res = SOSCreateErrorWithFormatAndArguments(errorCode, previousError, newError, formatOptions, format, va);
  78     va_end(va);
  79     return res;
  80 }
  81
  82 bool SOSCreateErrorWithFormatAndArguments(CFIndex errorCode, CFErrorRef previousError, CFErrorRef *newError,
  83                                           CFDictionaryRef formatOptions, CFStringRef format, va_list args) {
  84     SecCFCreateErrorWithFormatAndArguments(errorCode, kSOSErrorDomain, previousError, newError, formatOptions, format, args);
  85     return true;
  86 }
  87
  88
  89 //
  90 // Utility Functions
  91 //
  92
  93 static OSStatus GenerateECPairImp(int keySize, CFBooleanRef permanent, SecKeyRef* public, SecKeyRef *full)
  94 {
  95     static const CFStringRef sTempNameToUse = CFSTR("GenerateECPair Temporary Key - Shouldn't be live");
  96
  97     CFNumberRef signing_bitsize = CFNumberCreate(kCFAllocatorDefault, kCFNumberIntType, &keySize);
  98
  99     CFDictionaryRef keygen_parameters = CFDictionaryCreateForCFTypes(kCFAllocatorDefault,
 100                                                                      kSecAttrKeyType,       kSecAttrKeyTypeEC,
 101                                                                      kSecAttrKeySizeInBits, signing_bitsize,
 102                                                                      kSecAttrIsPermanent,   permanent,
 103                                                                      kSecAttrLabel,         sTempNameToUse,
 104                                                                      NULL);
 105     CFReleaseNull(signing_bitsize);
 106     OSStatus result = SecKeyGeneratePair(keygen_parameters, public, full);
 107     CFReleaseNull(keygen_parameters);
 108
 109     return result;
 110 }
 111
 112 OSStatus GenerateECPair(int keySize, SecKeyRef* public, SecKeyRef *full)
 113 {
 114     return GenerateECPairImp(keySize, kCFBooleanFalse, public, full);
 115 }
 116
 117 OSStatus GeneratePermanentECPair(int keySize, SecKeyRef* public, SecKeyRef *full)
 118 {
 119     return GenerateECPairImp(keySize, kCFBooleanTrue, public, full);
 120 }
 121
 122 static CFStringRef SOSCircleCopyDescriptionFromData(CFDataRef data)
 123 {
 124     CFErrorRef error = NULL;
 125     CFStringRef result = NULL;
 126
 127     SOSCircleRef circle = SOSCircleCreateFromData(kCFAllocatorDefault, data, &error);
 128
 129     if (circle)
 130         result = CFStringCreateWithFormat(kCFAllocatorDefault, NULL, CFSTR("%@"), circle);
 131
 132     CFReleaseSafe(circle);
 133
 134     return result;
 135 }
 136
 137 CFStringRef SOSItemsChangedCopyDescription(CFDictionaryRef changes, bool is_sender)
 138 {
 139     CFMutableStringRef string = CFStringCreateMutableCopy(kCFAllocatorDefault, 0, CFSTR("<Changes: {\n"));
 140
 141     CFDictionaryForEach(changes, ^(const void *key, const void *value) {
 142         CFStringRef value_description = NULL;
 143         if (isString(key) && isData(value)) {
 144             CFDataRef value_data = (CFDataRef) value;
 145             switch (SOSKVSKeyGetKeyType(key)) {
 146                 case kCircleKey:
 147                     value_description = SOSCircleCopyDescriptionFromData(value_data);
 148                     break;
 149                 case kMessageKey:
 150                     value_description = CFCopyDescription(value_data);
 151                     break;
 152                 default:
 153                     break;
 154             }
 155
 156         }
 157         CFStringAppendFormat(string, NULL, CFSTR("    '%@' %s %@\n"),
 158                              key,
 159                              is_sender ? "<=" : "=>",
 160                              value_description ? value_description : value);
 161
 162         CFReleaseNull(value_description);
 163     });
 164
 165     CFStringAppendFormat(string, NULL, CFSTR("}"));
 166
 167     return string;
 168 }
 169
 170 CFStringRef SOSCopyIDOfKey(SecKeyRef key, CFErrorRef *error)
 171 {
 172     const struct ccdigest_info * di = ccsha1_di();
 173     CFDataRef publicBytes = NULL;
 174     CFStringRef result = NULL;
 175
 176     uint8_t digest[di->output_size];
 177     char encoded[2 * di->output_size]; // Big enough for base64 encoding.
 178
 179     require_quiet(SecError(SecKeyCopyPublicBytes(key, &publicBytes), error, CFSTR("Failed to export public bytes %@"), key), fail);
 180
 181     ccdigest(di, CFDataGetLength(publicBytes), CFDataGetBytePtr(publicBytes), digest);
 182
 183     size_t length = SecBase64Encode(digest, sizeof(digest), encoded, sizeof(encoded));
 184     assert(length && length < sizeof(encoded));
 185     if (length > 26)
 186       length = 26;
 187     encoded[length] = 0;
 188     CFReleaseNull(publicBytes);
 189     return CFStringCreateWithCString(kCFAllocatorDefault, encoded, kCFStringEncodingASCII);
 190
 191 fail:
 192     CFReleaseNull(publicBytes);
 193     return result;
 194 }
 195
 196 CFGiblisGetSingleton(ccec_const_cp_t, SOSGetBackupKeyCurveParameters, sBackupKeyCurveParameters, ^{
 197     *sBackupKeyCurveParameters = ccec_cp_256();
 198 });
 199
 200
 201 //
 202 // We're expecting full entropy here, so we just need to stretch
 203 // via the PBKDF entropy rng. We'll choose a few iterations and no salt
 204 // since we don't get sent any.
 205 //
 206 const int kBackupKeyIterations = 20;
 207 const uint8_t sBackupKeySalt[] = { 0 };
 208 const int kBackupKeyMaxBytes = 256;
 209
 210 bool SOSPerformWithDeviceBackupFullKey(ccec_const_cp_t cp, CFDataRef entropy, CFErrorRef *error, void (^operation)(ccec_full_ctx_t fullKey))
 211 {
 212     bool result = false;
 213     ccec_full_ctx_decl_cp(cp, fullKey);
 214
 215     require_quiet(SOSGenerateDeviceBackupFullKey(fullKey, cp, entropy, error), exit);
 216
 217     operation(fullKey);
 218
 219     result = true;
 220 exit:
 221     ccec_full_ctx_clear_cp(cp, fullKey);
 222
 223     return result;
 224 }
 225
 226
 227 bool SOSGenerateDeviceBackupFullKey(ccec_full_ctx_t generatedKey, ccec_const_cp_t cp, CFDataRef entropy, CFErrorRef* error)
 228 {
 229     bool result = false;
 230     int cc_result = 0;
 231     struct ccrng_pbkdf2_prng_state pbkdf2_prng;
 232
 233     cc_result = ccrng_pbkdf2_prng_init(&pbkdf2_prng, kBackupKeyMaxBytes,
 234                                        CFDataGetLength(entropy), CFDataGetBytePtr(entropy),
 235                                        sizeof(sBackupKeySalt), sBackupKeySalt,
 236                                        kBackupKeyIterations);
 237     require_action_quiet(cc_result == 0, exit, SOSErrorCreate(kSOSErrorProcessingFailure, error, NULL, CFSTR("pbkdf rng init failed: %d"), cc_result));
 238
 239     cc_result = ccec_compact_generate_key(cp, (struct ccrng_state *) &pbkdf2_prng, generatedKey);
 240     require_action_quiet(cc_result == 0, exit, SOSErrorCreate(kSOSErrorProcessingFailure, error, NULL, CFSTR("Generate key failed: %d"), cc_result));
 241
 242     result = true;
 243 exit:
 244     bzero(&pbkdf2_prng, sizeof(pbkdf2_prng));
 245     return result;
 246
 247 }
 248
 249 CFDataRef SOSCopyDeviceBackupPublicKey(CFDataRef entropy, CFErrorRef *error)
 250 {
 251     CFDataRef result = NULL;
 252     CFMutableDataRef publicKeyData = NULL;
 253
 254     ccec_full_ctx_decl_cp(SOSGetBackupKeyCurveParameters(), fullKey);
 255
 256     require_quiet(SOSGenerateDeviceBackupFullKey(fullKey, SOSGetBackupKeyCurveParameters(), entropy, error), exit);
 257
 258     size_t space = ccec_compact_export_size(false, fullKey);
 259     publicKeyData = CFDataCreateMutableWithScratch(kCFAllocatorDefault, space);
 260     require_quiet(SecAllocationError(publicKeyData, error, CFSTR("Mutable data allocation")), exit);
 261
 262     ccec_compact_export(false, CFDataGetMutableBytePtr(publicKeyData), fullKey);
 263
 264     CFTransferRetained(result, publicKeyData);
 265
 266 exit:
 267     CFReleaseNull(publicKeyData);
 268     return result;
 269 }
 270
 271
 272 CFDataRef SOSDateCreate(void) {
 273     CFDateRef now = CFDateCreate(NULL, CFAbsoluteTimeGetCurrent());
 274     size_t bufsiz = der_sizeof_date(now, NULL);
 275     uint8_t buf[bufsiz];
 276     der_encode_date(now, NULL, buf, buf+bufsiz);
 277     CFReleaseNull(now);
 278     return CFDataCreate(NULL, buf, bufsiz);
 279 }
 280