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
  30 #if OCTAGON
  31
  32 @interface CKKSHealKeyHierarchyOperation ()
  33 @property NSBlockOperation* cloudkitModifyOperationFinished;
  34 @property CKOperationGroup* ckoperationGroup;
  35 @end
  36
  37 @implementation CKKSHealKeyHierarchyOperation
  38
  39 - (instancetype)init {
  40     return nil;
  41 }
  42 - (instancetype)initWithCKKSKeychainView:(CKKSKeychainView*)ckks ckoperationGroup:(CKOperationGroup*)ckoperationGroup {
  43     if(self = [super init]) {
  44         _ckks = ckks;
  45         _ckoperationGroup = ckoperationGroup;
  46     }
  47     return self;
  48 }
  49
  50 - (void)groupStart {
  51     /*
  52      * We've been invoked because something is wonky with the key hierarchy.
  53      *
  54      * Attempt to figure out what it is, and what we can do about it.
  55      *
  56      * The answer "nothing, everything is terrible" is acceptable.
  57      */
  58
  59     __weak __typeof(self) weakSelf = self;
  60
  61     CKKSKeychainView* ckks = self.ckks;
  62     if(!ckks) {
  63         ckkserror("ckksheal", ckks, "no CKKS object");
  64         return;
  65     }
  66
  67     if(self.cancelled) {
  68         ckksnotice("ckksheal", ckks, "CKKSHealKeyHierarchyOperation cancelled, quitting");
  69         return;
  70     }
  71
  72     // Synchronous, on some thread. Get back on the CKKS queue for SQL thread-safety.
  73     [ckks dispatchSync: ^bool{
  74         if(self.cancelled) {
  75             ckksnotice("ckksheal", ckks, "CKKSHealKeyHierarchyOperation cancelled, quitting");
  76             return false;
  77         }
  78
  79         NSError* error = nil;
  80
  81         CKKSCurrentKeySet* keyset = [[CKKSCurrentKeySet alloc] initForZone:ckks.zoneID];
  82
  83         bool changedCurrentTLK = false;
  84         bool changedCurrentClassA = false;
  85         bool changedCurrentClassC = false;
  86
  87         if(keyset.error) {
  88             self.error = keyset.error;
  89             ckkserror("ckksheal", ckks, "couldn't load current key set, attempting to proceed: %@", keyset.error);
  90         } else {
  91             ckksnotice("ckksheal", ckks, "Key set is %@", keyset);
  92         }
  93
  94         // There's all sorts of brokenness that could exist. For now, we check for:
  95         //
  96         //   1. Current key pointers are nil.
  97         //   2. Keys do not exist in local keychain (but TLK does)
  98         //   3. Keys do not exist in local keychain (including TLK)
  99         //
 100
 101         if(keyset.currentTLKPointer && keyset.currentClassAPointer && keyset.currentClassCPointer &&
 102            (!keyset.tlk || !keyset.classA || !keyset.classC)) {
 103             // Huh. No keys, but some current key pointers? Weird.
 104             // If we haven't done one yet, initiate a refetch of everything from cloudkit, and write down that we did so
 105             if(!ckks.keyStateMachineRefetched) {
 106                 ckksnotice("ckksheal", ckks, "Have current key pointers, but no keys. This is exceptional; requesting full refetch");
 107                 [ckks _onqueueAdvanceKeyStateMachineToState:SecCKKSZoneKeyStateNeedFullRefetch withError:nil];
 108                 return true;
 109             }
 110         }
 111
 112         // No current key records. That's... odd.
 113         if(!keyset.currentTLKPointer) {
 114             ckksnotice("ckksheal", ckks, "No current TLK pointer?");
 115             keyset.currentTLKPointer = [[CKKSCurrentKeyPointer alloc] initForClass: SecCKKSKeyClassTLK currentKeyUUID:nil zoneID:ckks.zoneID encodedCKRecord:nil];
 116         }
 117         if(!keyset.currentClassAPointer) {
 118             ckksnotice("ckksheal", ckks, "No current ClassA pointer?");
 119             keyset.currentClassAPointer = [[CKKSCurrentKeyPointer alloc] initForClass: SecCKKSKeyClassA currentKeyUUID:nil zoneID:ckks.zoneID encodedCKRecord:nil];
 120         }
 121         if(!keyset.currentClassCPointer) {
 122             ckksnotice("ckksheal", ckks, "No current ClassC pointer?");
 123             keyset.currentClassCPointer = [[CKKSCurrentKeyPointer alloc] initForClass: SecCKKSKeyClassC currentKeyUUID:nil zoneID:ckks.zoneID encodedCKRecord:nil];
 124         }
 125
 126
 127         if(keyset.currentTLKPointer.currentKeyUUID == nil || keyset.currentClassAPointer.currentKeyUUID == nil || keyset.currentClassCPointer.currentKeyUUID == nil ||
 128            keyset.tlk == nil || keyset.classA == nil || keyset.classC == nil) {
 129
 130             // The records exist, but are broken. Point them at something reasonable.
 131             NSArray<CKKSKey*>* keys = [CKKSKey allKeys:ckks.zoneID error:&error];
 132
 133             CKKSKey* newTLK = nil;
 134             CKKSKey* newClassAKey = nil;
 135             CKKSKey* newClassCKey = nil;
 136
 137             NSMutableArray<CKRecord *>* recordsToSave = [[NSMutableArray alloc] init];
 138             NSMutableArray<CKRecordID *>* recordIDsToDelete = [[NSMutableArray alloc] init];
 139
 140             // Find the current top local key. That's our new TLK.
 141             for(CKKSKey* key in keys) {
 142                 CKKSKey* topKey = [key topKeyInAnyState: &error];
 143                 if(newTLK == nil) {
 144                     newTLK = topKey;
 145                 } else if(![newTLK.uuid isEqualToString: topKey.uuid]) {
 146                     ckkserror("ckksheal", ckks, "key hierarchy has split: there's two top keys. Currently we don't handle this situation.");
 147                     [ckks _onqueueAdvanceKeyStateMachineToState: SecCKKSZoneKeyStateError withError: [NSError errorWithDomain:@"securityd"
 148                                                                                                                          code:0
 149                                                                                                                      userInfo:@{NSLocalizedDescriptionKey:
 150                                                                                                                                     [NSString stringWithFormat:@"Key hierarchy has split: %@ and %@ are roots", newTLK, topKey]}]];
 151                     return true;
 152                 }
 153             }
 154
 155             if(![ckks checkTLK: newTLK error: &error]) {
 156                 // Was this error "I've never seen that TLK before in my life"? If so, enter the "wait for TLK sync" state.
 157                 if(error && [error.domain isEqualToString: @"securityd"] && error.code == errSecItemNotFound) {
 158                     ckksnotice("ckksheal", ckks, "Received a TLK which we don't have in the local keychain(%@). Entering waitfortlk.", newTLK);
 159                     [ckks _onqueueAdvanceKeyStateMachineToState:SecCKKSZoneKeyStateWaitForTLK withError:nil];
 160                     return true;
 161                 } else if(error && [ckks.lockStateTracker isLockedError:error]) {
 162                     ckksnotice("ckkskey", ckks, "Received a TLK(%@), but keybag appears to be locked. Entering WaitForUnlock.", newTLK);
 163                     [ckks _onqueueAdvanceKeyStateMachineToState:SecCKKSZoneKeyStateWaitForUnlock withError:nil];
 164                     return true;
 165
 166                 } else {
 167                     // Otherwise, something has gone horribly wrong. enter error state.
 168                     ckkserror("ckksheal", ckks, "CKKS claims %@ is not a valid TLK: %@", newTLK, error);
 169                     NSError* newError = nil;
 170                     if(error) {
 171                         newError = [NSError errorWithDomain:@"securityd"
 172                                                        code:0
 173                                                    userInfo:@{NSLocalizedDescriptionKey: @"invalid TLK from CloudKit", NSUnderlyingErrorKey: error}];
 174                     } else {
 175                         newError = [NSError errorWithDomain:@"securityd"
 176                                                        code:0
 177                                                    userInfo:@{NSLocalizedDescriptionKey: @"invalid TLK from CloudKit"}];
 178                     }
 179                     [ckks _onqueueAdvanceKeyStateMachineToState:SecCKKSZoneKeyStateError withError:newError];
 180                     return true;
 181                 }
 182             }
 183
 184             // We have our new TLK.
 185             keyset.currentTLKPointer.currentKeyUUID = newTLK.uuid;
 186             changedCurrentTLK = true;
 187
 188             // Find some class A and class C keys directly under this one.
 189             for(CKKSKey* key in keys) {
 190                 if([key.parentKeyUUID isEqualToString: newTLK.uuid]) {
 191                     if((keyset.currentClassAPointer.currentKeyUUID == nil || keyset.classA == nil) &&
 192                        [key.keyclass isEqualToString: SecCKKSKeyClassA]) {
 193                         keyset.currentClassAPointer.currentKeyUUID = key.uuid;
 194                         changedCurrentClassA = true;
 195                     }
 196
 197                     if((keyset.currentClassCPointer.currentKeyUUID == nil || keyset.classC == nil) &&
 198                        [key.keyclass isEqualToString: SecCKKSKeyClassC]) {
 199                         keyset.currentClassCPointer.currentKeyUUID = key.uuid;
 200                         changedCurrentClassC = true;
 201                     }
 202                 }
 203             }
 204
 205             if(!keyset.currentClassAPointer.currentKeyUUID) {
 206                 newClassAKey = [CKKSKey randomKeyWrappedByParent:newTLK error:&error];
 207                 [newClassAKey saveKeyMaterialToKeychain:&error];
 208
 209                 if(error) {
 210                     ckkserror("ckksheal", ckks, "couldn't create new classA key: %@", error);
 211                     [ckks _onqueueAdvanceKeyStateMachineToState:SecCKKSZoneKeyStateError withError:[NSError errorWithDomain: @"securityd" code:0 userInfo:@{NSLocalizedDescriptionKey: @"couldn't create new classA key", NSUnderlyingErrorKey: error}]];
 212                 }
 213
 214                 keyset.currentClassAPointer.currentKeyUUID = newClassAKey.uuid;
 215                 changedCurrentClassA = true;
 216             }
 217             if(!keyset.currentClassCPointer.currentKeyUUID) {
 218                 newClassCKey = [CKKSKey randomKeyWrappedByParent:newTLK error:&error];
 219                 [newClassCKey saveKeyMaterialToKeychain:&error];
 220
 221                 if(error) {
 222                     ckkserror("ckksheal", ckks, "couldn't create new classC key: %@", error);
 223                     [ckks _onqueueAdvanceKeyStateMachineToState:SecCKKSZoneKeyStateError withError:[NSError errorWithDomain: @"securityd" code:0 userInfo:@{NSLocalizedDescriptionKey: @"couldn't create new classC key", NSUnderlyingErrorKey: error}]];
 224                 }
 225
 226                 keyset.currentClassCPointer.currentKeyUUID = newClassCKey.uuid;
 227                 changedCurrentClassC = true;
 228             }
 229
 230             // Note: we never make a new TLK here. So, don't save it back to CloudKit.
 231             //if(newTLK) {
 232             //    [recordsToSave addObject: [newTLK       CKRecordWithZoneID: ckks.zoneID]];
 233             //}
 234             if(newClassAKey) {
 235                 [recordsToSave addObject: [newClassAKey CKRecordWithZoneID: ckks.zoneID]];
 236             }
 237             if(newClassCKey) {
 238                 [recordsToSave addObject: [newClassCKey CKRecordWithZoneID: ckks.zoneID]];
 239             }
 240
 241             if(changedCurrentTLK) {
 242                 [recordsToSave addObject: [keyset.currentTLKPointer    CKRecordWithZoneID: ckks.zoneID]];
 243             }
 244             if(changedCurrentClassA) {
 245                 [recordsToSave addObject: [keyset.currentClassAPointer CKRecordWithZoneID: ckks.zoneID]];
 246             }
 247             if(changedCurrentClassC) {
 248                 [recordsToSave addObject: [keyset.currentClassCPointer CKRecordWithZoneID: ckks.zoneID]];
 249             }
 250
 251             ckksinfo("ckksheal", ckks, "Saving new keys %@ to cloudkit %@", recordsToSave, ckks.database);
 252
 253             // Use the spare operation trick to wait for the CKModifyRecordsOperation to complete
 254             self.cloudkitModifyOperationFinished = [NSBlockOperation named:@"heal-cloudkit-modify-operation-finished" withBlock:^{}];
 255             [self dependOnBeforeGroupFinished: self.cloudkitModifyOperationFinished];
 256
 257             CKModifyRecordsOperation* modifyRecordsOp = nil;
 258
 259             // Get the CloudKit operation ready...
 260             modifyRecordsOp = [[CKModifyRecordsOperation alloc] initWithRecordsToSave:recordsToSave recordIDsToDelete:recordIDsToDelete];
 261             modifyRecordsOp.atomic = YES;
 262             modifyRecordsOp.longLived = NO; // The keys are only in memory; mark this explicitly not long-lived
 263             modifyRecordsOp.timeoutIntervalForRequest = 2;
 264             modifyRecordsOp.qualityOfService = NSQualityOfServiceUtility;  // relatively important. Use Utility.
 265             modifyRecordsOp.group = self.ckoperationGroup;
 266             ckksnotice("ckksheal", ckks, "Operation group is %@", self.ckoperationGroup);
 267
 268             modifyRecordsOp.perRecordCompletionBlock = ^(CKRecord *record, NSError * _Nullable error) {
 269                 __strong __typeof(weakSelf) strongSelf = weakSelf;
 270                 __strong __typeof(strongSelf.ckks) blockCKKS = strongSelf.ckks;
 271
 272                 // These should all fail or succeed as one. Do the hard work in the records completion block.
 273                 if(!error) {
 274                     ckksnotice("ckksheal", blockCKKS, "Successfully completed upload for %@", record.recordID.recordName);
 275                 } else {
 276                     ckkserror("ckksheal", blockCKKS, "error on row: %@ %@", error, record);
 277                 }
 278             };
 279
 280             modifyRecordsOp.modifyRecordsCompletionBlock = ^(NSArray<CKRecord *> *savedRecords, NSArray<CKRecordID *> *deletedRecordIDs, NSError *error) {
 281                 __strong __typeof(weakSelf) strongSelf = weakSelf;
 282                 __strong __typeof(strongSelf.ckks) strongCKKS = strongSelf.ckks;
 283                 if(!strongSelf) {
 284                     secerror("ckks: received callback for released object");
 285                     return;
 286                 }
 287
 288                 ckksnotice("ckksheal", strongCKKS, "Completed Key Heal CloudKit operation with error: %@", error);
 289
 290                 [strongCKKS dispatchSync: ^bool{
 291                     if(error == nil) {
 292                         // Success. Persist the keys to the CKKS database.
 293
 294                         // Save the new CKRecords to the before persisting to database
 295                         for(CKRecord* record in savedRecords) {
 296                             if([newTLK matchesCKRecord: record]) {
 297                                 newTLK.storedCKRecord = record;
 298                             } else if([newClassAKey matchesCKRecord: record]) {
 299                                 newClassAKey.storedCKRecord = record;
 300                             } else if([newClassCKey matchesCKRecord: record]) {
 301                                 newClassCKey.storedCKRecord = record;
 302
 303                             } else if([keyset.currentTLKPointer matchesCKRecord: record]) {
 304                                 keyset.currentTLKPointer.storedCKRecord = record;
 305                             } else if([keyset.currentClassAPointer matchesCKRecord: record]) {
 306                                 keyset.currentClassAPointer.storedCKRecord = record;
 307                             } else if([keyset.currentClassCPointer matchesCKRecord: record]) {
 308                                 keyset.currentClassCPointer.storedCKRecord = record;
 309                             }
 310                         }
 311
 312                         NSError* localerror = nil;
 313
 314                         [newTLK       saveToDatabaseAsOnlyCurrentKeyForClassAndState: &localerror];
 315                         [newClassAKey saveToDatabaseAsOnlyCurrentKeyForClassAndState: &localerror];
 316                         [newClassCKey saveToDatabaseAsOnlyCurrentKeyForClassAndState: &localerror];
 317
 318                         [keyset.currentTLKPointer    saveToDatabase: &localerror];
 319                         [keyset.currentClassAPointer saveToDatabase: &localerror];
 320                         [keyset.currentClassCPointer saveToDatabase: &localerror];
 321
 322                         if(localerror != nil) {
 323                             ckkserror("ckksheal", strongCKKS, "couldn't save new key hierarchy to database; this is very bad: %@", localerror);
 324                             [strongCKKS _onqueueAdvanceKeyStateMachineToState: SecCKKSZoneKeyStateError withError: localerror];
 325                             return false;
 326                         } else {
 327                             // Everything is groovy. HOWEVER, we might still not have processed the keys. Ask for that!
 328                             [strongCKKS _onqueueKeyStateMachineRequestProcess];
 329                             [strongCKKS _onqueueAdvanceKeyStateMachineToState: SecCKKSZoneKeyStateReady withError: nil];
 330                         }
 331                     } else {
 332                         // ERROR. This isn't a total-failure error state, but one that should kick off a healing process.
 333                         ckkserror("ckksheal", strongCKKS, "couldn't save new key hierarchy to CloudKit: %@", error);
 334                         [strongCKKS _onqueueAdvanceKeyStateMachineToState: SecCKKSZoneKeyStateNewTLKsFailed withError: nil];
 335                     }
 336                     return true;
 337                 }];
 338
 339                 // Notify that we're done
 340                 [strongSelf.operationQueue addOperation: strongSelf.cloudkitModifyOperationFinished];
 341             };
 342
 343             [ckks.database addOperation: modifyRecordsOp];
 344             return true;
 345         }
 346
 347         [keyset.tlk loadKeyMaterialFromKeychain:&error];
 348         if(error && [ckks.lockStateTracker isLockedError:error]) {
 349             ckksnotice("ckkskey", ckks, "Failed to load TLK from keychain, keybag is locked. Entering WaitForUnlock: %@", error);
 350             [ckks _onqueueAdvanceKeyStateMachineToState:SecCKKSZoneKeyStateWaitForUnlock withError:nil];
 351             return false;
 352         } else if(error) {
 353             ckkserror("ckksheal", ckks, "No TLK in keychain, triggering move to bad state: %@", error);
 354             [ckks _onqueueAdvanceKeyStateMachineToState: SecCKKSZoneKeyStateWaitForTLK withError: nil];
 355             return false;
 356         }
 357
 358         if(![self ensureKeyPresent:keyset.classA]) {
 359             return false;
 360         }
 361
 362         if(![self ensureKeyPresent:keyset.classC]) {
 363             return false;
 364         }
 365
 366         // Seems good to us. Check if we're ready?
 367         [ckks _onqueueAdvanceKeyStateMachineToState: SecCKKSZoneKeyStateReady withError: nil];
 368
 369         return true;
 370     }];
 371 }
 372
 373 - (bool)ensureKeyPresent:(CKKSKey*)key {
 374     NSError* error = nil;
 375     CKKSKeychainView* ckks = self.ckks;
 376
 377     [key loadKeyMaterialFromKeychain:&error];
 378     if(error) {
 379         ckkserror("ckksheal", ckks, "Couldn't load classC key from keychain. Attempting recovery: %@", error);
 380         error = nil;
 381         [key unwrapViaKeyHierarchy: &error];
 382         if(error) {
 383             ckkserror("ckksheal", ckks, "Couldn't unwrap class C key using key hierarchy. Keys are broken, quitting: %@", error);
 384             [ckks _onqueueAdvanceKeyStateMachineToState: SecCKKSZoneKeyStateError withError: error];
 385             self.error = error;
 386             return false;
 387         }
 388         [key saveKeyMaterialToKeychain:&error];
 389         if(error) {
 390             ckkserror("ckksheal", ckks, "Couldn't save class C key to keychain: %@", error);
 391             [ckks _onqueueAdvanceKeyStateMachineToState: SecCKKSZoneKeyStateError withError: error];
 392             self.error = error;
 393             return false;
 394         }
 395     }
 396     return true;
 397 }
 398
 399 - (void)cancel {
 400     [self.cloudkitModifyOperationFinished cancel];
 401     [super cancel];
 402 }
 403
 404 @end;
 405
 406 #endif