keychain/ckks/CKKSHealKeyHierarchyOperation.m

   1 /*
   2  * Copyright (c) 2017 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 #import "CKKSKeychainView.h"
  25 #import "CKKSCurrentKeyPointer.h"
  26 #import "CKKSKey.h"
  27 #import "CKKSHealKeyHierarchyOperation.h"
  28 #import "CKKSGroupOperation.h"
  29 #import "CKKSAnalytics.h"
  30 #import "keychain/ckks/CloudKitCategories.h"
  31
  32 #if OCTAGON
  33
  34 @interface CKKSHealKeyHierarchyOperation ()
  35 @property NSBlockOperation* cloudkitModifyOperationFinished;
  36 @property CKOperationGroup* ckoperationGroup;
  37 @end
  38
  39 @implementation CKKSHealKeyHierarchyOperation
  40
  41 - (instancetype)init {
  42     return nil;
  43 }
  44 - (instancetype)initWithCKKSKeychainView:(CKKSKeychainView*)ckks ckoperationGroup:(CKOperationGroup*)ckoperationGroup {
  45     if(self = [super init]) {
  46         _ckks = ckks;
  47         _ckoperationGroup = ckoperationGroup;
  48     }
  49     return self;
  50 }
  51
  52 - (void)groupStart {
  53     /*
  54      * We've been invoked because something is wonky with the key hierarchy.
  55      *
  56      * Attempt to figure out what it is, and what we can do about it.
  57      *
  58      * The answer "nothing, everything is terrible" is acceptable.
  59      */
  60
  61     __weak __typeof(self) weakSelf = self;
  62
  63     CKKSKeychainView* ckks = self.ckks;
  64     if(!ckks) {
  65         ckkserror("ckksheal", ckks, "no CKKS object");
  66         return;
  67     }
  68
  69     if(self.cancelled) {
  70         ckksnotice("ckksheal", ckks, "CKKSHealKeyHierarchyOperation cancelled, quitting");
  71         return;
  72     }
  73
  74     // Synchronous, on some thread. Get back on the CKKS queue for SQL thread-safety.
  75     [ckks dispatchSyncWithAccountKeys: ^bool{
  76         if(self.cancelled) {
  77             ckksnotice("ckksheal", ckks, "CKKSHealKeyHierarchyOperation cancelled, quitting");
  78             return false;
  79         }
  80
  81         NSError* error = nil;
  82
  83         CKKSCurrentKeySet* keyset = [[CKKSCurrentKeySet alloc] initForZone:ckks.zoneID];
  84
  85         bool changedCurrentTLK = false;
  86         bool changedCurrentClassA = false;
  87         bool changedCurrentClassC = false;
  88
  89         if(keyset.error) {
  90             self.error = keyset.error;
  91             ckkserror("ckksheal", ckks, "couldn't load current key set, attempting to proceed: %@", keyset.error);
  92         } else {
  93             ckksnotice("ckksheal", ckks, "Key set is %@", keyset);
  94         }
  95
  96         // There's all sorts of brokenness that could exist. For now, we check for:
  97         //
  98         //   1. Current key pointers are nil.
  99         //   2. Keys do not exist in local keychain (but TLK does)
 100         //   3. Keys do not exist in local keychain (including TLK)
 101         //   4. Class A or Class C keys do not wrap immediately to top TLK.
 102         //
 103
 104         if(keyset.currentTLKPointer && keyset.currentClassAPointer && keyset.currentClassCPointer &&
 105            (!keyset.tlk || !keyset.classA || !keyset.classC)) {
 106             // Huh. No keys, but some current key pointers? Weird.
 107             // If we haven't done one yet, initiate a refetch of everything from cloudkit, and write down that we did so
 108             if(!ckks.keyStateMachineRefetched) {
 109                 ckksnotice("ckksheal", ckks, "Have current key pointers, but no keys. This is exceptional; requesting full refetch");
 110                 [ckks _onqueueAdvanceKeyStateMachineToState:SecCKKSZoneKeyStateNeedFullRefetch withError:nil];
 111                 return true;
 112             }
 113         }
 114
 115         // No current key records. That's... odd.
 116         if(!keyset.currentTLKPointer) {
 117             ckksnotice("ckksheal", ckks, "No current TLK pointer?");
 118             keyset.currentTLKPointer = [[CKKSCurrentKeyPointer alloc] initForClass: SecCKKSKeyClassTLK currentKeyUUID:nil zoneID:ckks.zoneID encodedCKRecord:nil];
 119         }
 120         if(!keyset.currentClassAPointer) {
 121             ckksnotice("ckksheal", ckks, "No current ClassA pointer?");
 122             keyset.currentClassAPointer = [[CKKSCurrentKeyPointer alloc] initForClass: SecCKKSKeyClassA currentKeyUUID:nil zoneID:ckks.zoneID encodedCKRecord:nil];
 123         }
 124         if(!keyset.currentClassCPointer) {
 125             ckksnotice("ckksheal", ckks, "No current ClassC pointer?");
 126             keyset.currentClassCPointer = [[CKKSCurrentKeyPointer alloc] initForClass: SecCKKSKeyClassC currentKeyUUID:nil zoneID:ckks.zoneID encodedCKRecord:nil];
 127         }
 128
 129
 130         if(keyset.currentTLKPointer.currentKeyUUID == nil || keyset.currentClassAPointer.currentKeyUUID == nil || keyset.currentClassCPointer.currentKeyUUID == nil ||
 131            keyset.tlk == nil || keyset.classA == nil || keyset.classC == nil ||
 132            ![keyset.classA.parentKeyUUID isEqualToString: keyset.tlk.uuid] || ![keyset.classC.parentKeyUUID isEqualToString: keyset.tlk.uuid]) {
 133
 134             // The records exist, but are broken. Point them at something reasonable.
 135             NSArray<CKKSKey*>* keys = [CKKSKey allKeys:ckks.zoneID error:&error];
 136
 137             CKKSKey* newTLK = nil;
 138             CKKSKey* newClassAKey = nil;
 139             CKKSKey* newClassCKey = nil;
 140
 141             NSMutableArray<CKRecord *>* recordsToSave = [[NSMutableArray alloc] init];
 142             NSMutableArray<CKRecordID *>* recordIDsToDelete = [[NSMutableArray alloc] init];
 143
 144             // Find the current top local key. That's our new TLK.
 145             for(CKKSKey* key in keys) {
 146                 CKKSKey* topKey = [key topKeyInAnyState: &error];
 147                 if(newTLK == nil) {
 148                     newTLK = topKey;
 149                 } else if(![newTLK.uuid isEqualToString: topKey.uuid]) {
 150                     ckkserror("ckksheal", ckks, "key hierarchy has split: there's two top keys. Currently we don't handle this situation.");
 151                     [ckks _onqueueAdvanceKeyStateMachineToState: SecCKKSZoneKeyStateError withError: [NSError errorWithDomain:CKKSErrorDomain
 152                                                                                                                          code:CKKSSplitKeyHierarchy
 153                                                                                                                      userInfo:@{NSLocalizedDescriptionKey:
 154                                                                                                                                     [NSString stringWithFormat:@"Key hierarchy has split: %@ and %@ are roots", newTLK, topKey]}]];
 155                     return true;
 156                 }
 157             }
 158
 159             if(![ckks _onqueueWithAccountKeysCheckTLK: newTLK error: &error]) {
 160                 // Was this error "I've never seen that TLK before in my life"? If so, enter the "wait for TLK sync" state.
 161                 if(error && [error.domain isEqualToString: @"securityd"] && error.code == errSecItemNotFound) {
 162                     ckksnotice("ckksheal", ckks, "Received a TLK which we don't have in the local keychain(%@). Entering waitfortlk.", newTLK);
 163                     [ckks _onqueueAdvanceKeyStateMachineToState:SecCKKSZoneKeyStateWaitForTLK withError:nil];
 164                     return true;
 165                 } else if(error && [ckks.lockStateTracker isLockedError:error]) {
 166                     ckksnotice("ckkskey", ckks, "Received a TLK(%@), but keybag appears to be locked. Entering WaitForUnlock.", newTLK);
 167                     [ckks _onqueueAdvanceKeyStateMachineToState:SecCKKSZoneKeyStateWaitForUnlock withError:nil];
 168                     return true;
 169
 170                 } else {
 171                     // Otherwise, something has gone horribly wrong. enter error state.
 172                     ckkserror("ckksheal", ckks, "CKKS claims %@ is not a valid TLK: %@", newTLK, error);
 173                     NSError* newError = [NSError errorWithDomain:CKKSErrorDomain code:CKKSInvalidTLK description:@"Invalid TLK from CloudKit (during heal)" underlying:error];
 174                     [ckks _onqueueAdvanceKeyStateMachineToState:SecCKKSZoneKeyStateError withError:newError];
 175                     return true;
 176                 }
 177             }
 178
 179             // We have our new TLK.
 180             if(![keyset.currentTLKPointer.currentKeyUUID isEqualToString: newTLK.uuid]) {
 181                 // And it's even actually new!
 182                 keyset.tlk = newTLK;
 183                 keyset.currentTLKPointer.currentKeyUUID = newTLK.uuid;
 184                 changedCurrentTLK = true;
 185             }
 186
 187             // Find some class A and class C keys directly under this one.
 188             for(CKKSKey* key in keys) {
 189                 if([key.parentKeyUUID isEqualToString: newTLK.uuid]) {
 190                     if([key.keyclass isEqualToString: SecCKKSKeyClassA] &&
 191                            (keyset.currentClassAPointer.currentKeyUUID == nil ||
 192                             ![keyset.classA.parentKeyUUID isEqualToString: newTLK.uuid] ||
 193                             keyset.classA == nil)
 194                        ) {
 195                         keyset.classA = key;
 196                         keyset.currentClassAPointer.currentKeyUUID = key.uuid;
 197                         changedCurrentClassA = true;
 198                     }
 199
 200                     if([key.keyclass isEqualToString: SecCKKSKeyClassC] &&
 201                             (keyset.currentClassCPointer.currentKeyUUID == nil ||
 202                              ![keyset.classC.parentKeyUUID isEqualToString: newTLK.uuid] ||
 203                              keyset.classC == nil)
 204                        ) {
 205                         keyset.classC = key;
 206                         keyset.currentClassCPointer.currentKeyUUID = key.uuid;
 207                         changedCurrentClassC = true;
 208                     }
 209                 }
 210             }
 211
 212             if(!keyset.currentClassAPointer.currentKeyUUID) {
 213                 newClassAKey = [CKKSKey randomKeyWrappedByParent:newTLK error:&error];
 214                 [newClassAKey saveKeyMaterialToKeychain:&error];
 215
 216                 if(error && [ckks.lockStateTracker isLockedError:error]) {
 217                     ckksnotice("ckksheal", ckks, "Couldn't create a new class A key, but keybag appears to be locked. Entering waitforunlock.");
 218                     [ckks _onqueueAdvanceKeyStateMachineToState:SecCKKSZoneKeyStateWaitForUnlock withError:error];
 219                     return true;
 220                 } else if(error) {
 221                     ckkserror("ckksheal", ckks, "couldn't create new classA key: %@", error);
 222                     [ckks _onqueueAdvanceKeyStateMachineToState:SecCKKSZoneKeyStateError withError:error];
 223                     return true;
 224                 }
 225
 226                 keyset.classA = newClassAKey;
 227                 keyset.currentClassAPointer.currentKeyUUID = newClassAKey.uuid;
 228                 changedCurrentClassA = true;
 229             }
 230             if(!keyset.currentClassCPointer.currentKeyUUID) {
 231                 newClassCKey = [CKKSKey randomKeyWrappedByParent:newTLK error:&error];
 232                 [newClassCKey saveKeyMaterialToKeychain:&error];
 233
 234                 if(error && [ckks.lockStateTracker isLockedError:error]) {
 235                     ckksnotice("ckksheal", ckks, "Couldn't create a new class C key, but keybag appears to be locked. Entering waitforunlock.");
 236                     [ckks _onqueueAdvanceKeyStateMachineToState:SecCKKSZoneKeyStateWaitForUnlock withError:error];
 237                     return true;
 238                 } else if(error) {
 239                     ckkserror("ckksheal", ckks, "couldn't create new class C key: %@", error);
 240                     [ckks _onqueueAdvanceKeyStateMachineToState:SecCKKSZoneKeyStateError withError:error];
 241                     return true;
 242                 }
 243
 244                 keyset.classC = newClassCKey;
 245                 keyset.currentClassCPointer.currentKeyUUID = newClassCKey.uuid;
 246                 changedCurrentClassC = true;
 247             }
 248
 249             ckksnotice("ckksheal", ckks, "Attempting to move to new key hierarchy: %@", keyset);
 250
 251             // Note: we never make a new TLK here. So, don't save it back to CloudKit.
 252             //if(newTLK) {
 253             //    [recordsToSave addObject: [newTLK       CKRecordWithZoneID: ckks.zoneID]];
 254             //}
 255             if(newClassAKey) {
 256                 [recordsToSave addObject: [newClassAKey CKRecordWithZoneID: ckks.zoneID]];
 257             }
 258             if(newClassCKey) {
 259                 [recordsToSave addObject: [newClassCKey CKRecordWithZoneID: ckks.zoneID]];
 260             }
 261
 262             if(changedCurrentTLK) {
 263                 [recordsToSave addObject: [keyset.currentTLKPointer    CKRecordWithZoneID: ckks.zoneID]];
 264             }
 265             if(changedCurrentClassA) {
 266                 [recordsToSave addObject: [keyset.currentClassAPointer CKRecordWithZoneID: ckks.zoneID]];
 267             }
 268             if(changedCurrentClassC) {
 269                 [recordsToSave addObject: [keyset.currentClassCPointer CKRecordWithZoneID: ckks.zoneID]];
 270             }
 271
 272             // We've selected a new TLK. Compute any TLKShares that should go along with it.
 273             NSSet<CKKSTLKShare*>* tlkShares = [ckks _onqueueCreateMissingKeyShares:keyset.tlk
 274                                                                              error:&error];
 275             if(error) {
 276                 ckkserror("ckksshare", ckks, "Unable to create TLK shares for new tlk: %@", error);
 277                 return false;
 278             }
 279
 280             for(CKKSTLKShare* share in tlkShares) {
 281                 CKRecord* record = [share CKRecordWithZoneID:ckks.zoneID];
 282                 [recordsToSave addObject: record];
 283             }
 284
 285             // Kick off the CKOperation
 286
 287             ckksnotice("ckksheal", ckks, "Saving new records %@", recordsToSave);
 288
 289             // Use the spare operation trick to wait for the CKModifyRecordsOperation to complete
 290             self.cloudkitModifyOperationFinished = [NSBlockOperation named:@"heal-cloudkit-modify-operation-finished" withBlock:^{}];
 291             [self dependOnBeforeGroupFinished: self.cloudkitModifyOperationFinished];
 292
 293             CKModifyRecordsOperation* modifyRecordsOp = nil;
 294
 295             NSMutableDictionary<CKRecordID*, CKRecord*>* attemptedRecords = [[NSMutableDictionary alloc] init];
 296             for(CKRecord* record in recordsToSave) {
 297                 attemptedRecords[record.recordID] = record;
 298             }
 299
 300             // Get the CloudKit operation ready...
 301             modifyRecordsOp = [[CKModifyRecordsOperation alloc] initWithRecordsToSave:recordsToSave recordIDsToDelete:recordIDsToDelete];
 302             modifyRecordsOp.atomic = YES;
 303             modifyRecordsOp.longLived = NO; // The keys are only in memory; mark this explicitly not long-lived
 304             modifyRecordsOp.qualityOfService = NSQualityOfServiceUserInitiated;  // This needs to happen for CKKS to be usable by PCS/cloudd. Make it happen.
 305             modifyRecordsOp.group = self.ckoperationGroup;
 306             ckksnotice("ckksheal", ckks, "Operation group is %@", self.ckoperationGroup);
 307
 308             modifyRecordsOp.perRecordCompletionBlock = ^(CKRecord *record, NSError * _Nullable error) {
 309                 __strong __typeof(weakSelf) strongSelf = weakSelf;
 310                 __strong __typeof(strongSelf.ckks) blockCKKS = strongSelf.ckks;
 311
 312                 // These should all fail or succeed as one. Do the hard work in the records completion block.
 313                 if(!error) {
 314                     ckksnotice("ckksheal", blockCKKS, "Successfully completed upload for %@", record.recordID.recordName);
 315                 } else {
 316                     ckkserror("ckksheal", blockCKKS, "error on row: %@ %@", error, record);
 317                 }
 318             };
 319
 320             modifyRecordsOp.modifyRecordsCompletionBlock = ^(NSArray<CKRecord *> *savedRecords, NSArray<CKRecordID *> *deletedRecordIDs, NSError *error) {
 321                 __strong __typeof(weakSelf) strongSelf = weakSelf;
 322                 __strong __typeof(strongSelf.ckks) strongCKKS = strongSelf.ckks;
 323                 if(!strongSelf) {
 324                     secerror("ckks: received callback for released object");
 325                     return;
 326                 }
 327
 328                 ckksnotice("ckksheal", strongCKKS, "Completed Key Heal CloudKit operation with error: %@", error);
 329
 330                 [strongCKKS dispatchSyncWithAccountKeys: ^bool{
 331                     if(error == nil) {
 332                         [[CKKSAnalytics logger] logSuccessForEvent:CKKSEventProcessHealKeyHierarchy inView:ckks];
 333                         // Success. Persist the keys to the CKKS database.
 334
 335                         // Save the new CKRecords to the before persisting to database
 336                         for(CKRecord* record in savedRecords) {
 337                             if([newTLK matchesCKRecord: record]) {
 338                                 newTLK.storedCKRecord = record;
 339                             } else if([newClassAKey matchesCKRecord: record]) {
 340                                 newClassAKey.storedCKRecord = record;
 341                             } else if([newClassCKey matchesCKRecord: record]) {
 342                                 newClassCKey.storedCKRecord = record;
 343
 344                             } else if([keyset.currentTLKPointer matchesCKRecord: record]) {
 345                                 keyset.currentTLKPointer.storedCKRecord = record;
 346                             } else if([keyset.currentClassAPointer matchesCKRecord: record]) {
 347                                 keyset.currentClassAPointer.storedCKRecord = record;
 348                             } else if([keyset.currentClassCPointer matchesCKRecord: record]) {
 349                                 keyset.currentClassCPointer.storedCKRecord = record;
 350                             }
 351                         }
 352
 353                         NSError* localerror = nil;
 354
 355                         [newTLK       saveToDatabaseAsOnlyCurrentKeyForClassAndState: &localerror];
 356                         [newClassAKey saveToDatabaseAsOnlyCurrentKeyForClassAndState: &localerror];
 357                         [newClassCKey saveToDatabaseAsOnlyCurrentKeyForClassAndState: &localerror];
 358
 359                         [keyset.currentTLKPointer    saveToDatabase: &localerror];
 360                         [keyset.currentClassAPointer saveToDatabase: &localerror];
 361                         [keyset.currentClassCPointer saveToDatabase: &localerror];
 362
 363                         // save all the TLKShares, too
 364                         for(CKKSTLKShare* share in tlkShares) {
 365                             [share saveToDatabase:&localerror];
 366                         }
 367
 368                         if(localerror != nil) {
 369                             ckkserror("ckksheal", strongCKKS, "couldn't save new key hierarchy to database; this is very bad: %@", localerror);
 370                             [strongCKKS _onqueueAdvanceKeyStateMachineToState: SecCKKSZoneKeyStateError withError: localerror];
 371                             return false;
 372                         } else {
 373                             // Everything is groovy. HOWEVER, we might still not have processed the keys. Ask for that!
 374                             [strongCKKS _onqueueKeyStateMachineRequestProcess];
 375                             [strongCKKS _onqueueAdvanceKeyStateMachineToState: SecCKKSZoneKeyStateReady withError: nil];
 376                         }
 377                     } else {
 378                         // ERROR. This isn't a total-failure error state, but one that should kick off a healing process.
 379                         [[CKKSAnalytics logger] logUnrecoverableError:error forEvent:CKKSEventProcessHealKeyHierarchy inView:ckks withAttributes:NULL];
 380                         ckkserror("ckksheal", strongCKKS, "couldn't save new key hierarchy to CloudKit: %@", error);
 381                         [strongCKKS _onqueueCKWriteFailed:error attemptedRecordsChanged:attemptedRecords];
 382                         [strongCKKS _onqueueAdvanceKeyStateMachineToState: SecCKKSZoneKeyStateNewTLKsFailed withError: nil];
 383                     }
 384                     return true;
 385                 }];
 386
 387                 // Notify that we're done
 388                 [strongSelf.operationQueue addOperation: strongSelf.cloudkitModifyOperationFinished];
 389             };
 390
 391             [ckks.database addOperation: modifyRecordsOp];
 392             return true;
 393         }
 394
 395         // Check if CKKS can recover this TLK.
 396         bool haveTLK = [ckks _onqueueWithAccountKeysCheckTLK:keyset.tlk error:&error];
 397         if(error && [ckks.lockStateTracker isLockedError:error]) {
 398             ckksnotice("ckkskey", ckks, "Failed to load TLK from keychain, keybag is locked. Entering waitforunlock: %@", error);
 399             [ckks _onqueueAdvanceKeyStateMachineToState:SecCKKSZoneKeyStateWaitForUnlock withError:nil];
 400             return false;
 401         } else if(error && error.code == errSecItemNotFound) {
 402             ckkserror("ckksheal", ckks, "CKKS couldn't find TLK, triggering move to wait state: %@", error);
 403             [ckks _onqueueAdvanceKeyStateMachineToState: SecCKKSZoneKeyStateWaitForTLK withError: nil];
 404
 405         } else if(!haveTLK) {
 406             ckkserror("ckksheal", ckks, "CKKS errored examining TLK, triggering move to bad state: %@", error);
 407             [ckks _onqueueAdvanceKeyStateMachineToState:SecCKKSZoneKeyStateError withError:error];
 408             return false;
 409         }
 410
 411         if(![self ensureKeyPresent:keyset.tlk]) {
 412             return false;
 413         }
 414
 415         if(![self ensureKeyPresent:keyset.classA]) {
 416             return false;
 417         }
 418
 419         if(![self ensureKeyPresent:keyset.classC]) {
 420             return false;
 421         }
 422
 423         // Seems good to us. Check if we're ready?
 424         [ckks _onqueueAdvanceKeyStateMachineToState: SecCKKSZoneKeyStateReady withError: nil];
 425
 426         return true;
 427     }];
 428 }
 429
 430 - (bool)ensureKeyPresent:(CKKSKey*)key {
 431     NSError* error = nil;
 432     CKKSKeychainView* ckks = self.ckks;
 433
 434     [key loadKeyMaterialFromKeychain:&error];
 435     if(error) {
 436         ckkserror("ckksheal", ckks, "Couldn't load key(%@) from keychain. Attempting recovery: %@", key, error);
 437         error = nil;
 438         [key unwrapViaKeyHierarchy: &error];
 439         if(error) {
 440             ckkserror("ckksheal", ckks, "Couldn't unwrap key(%@) using key hierarchy. Keys are broken, quitting: %@", key, error);
 441             [ckks _onqueueAdvanceKeyStateMachineToState: SecCKKSZoneKeyStateError withError: error];
 442             self.error = error;
 443             return false;
 444         }
 445         [key saveKeyMaterialToKeychain:&error];
 446         if(error) {
 447             ckkserror("ckksheal", ckks, "Couldn't save key(%@) to keychain: %@", key, error);
 448             [ckks _onqueueAdvanceKeyStateMachineToState: SecCKKSZoneKeyStateError withError: error];
 449             self.error = error;
 450             return false;
 451         }
 452     }
 453     return true;
 454 }
 455
 456 - (void)cancel {
 457     [self.cloudkitModifyOperationFinished cancel];
 458     [super cancel];
 459 }
 460
 461 @end;
 462
 463 #endif