keychain/ckks/CKKSSynchronizeOperation.m

   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 #import "CKKSKeychainView.h"
  25 #import "CKKSGroupOperation.h"
  26 #import "CKKSSynchronizeOperation.h"
  27 #import "CKKSFetchAllRecordZoneChangesOperation.h"
  28 #import "CKKSScanLocalItemsOperation.h"
  29 #import "keychain/ckks/CloudKitCategories.h"
  30 #import "keychain/categories/NSError+UsefulConstructors.h"
  31 #import "keychain/ot/ObjCImprovements.h"
  32
  33 #if OCTAGON
  34
  35 @interface CKKSSynchronizeOperation ()
  36 @property int32_t restartCount;
  37 @end
  38
  39 @implementation CKKSSynchronizeOperation
  40
  41 - (instancetype)init {
  42     return nil;
  43 }
  44 - (instancetype)initWithCKKSKeychainView:(CKKSKeychainView*)ckks {
  45     if(self = [super init]) {
  46         _ckks = ckks;
  47         _restartCount = 0;
  48     }
  49     return self;
  50 }
  51
  52 - (void)groupStart {
  53     WEAKIFY(self);
  54
  55     /*
  56      * Synchronizations (or resynchronizations) are complicated beasts. We will:
  57      *
  58      *  1. Finish processing the outgoing queue. You can't be in-sync with cloudkit if you have an update that hasn't propagated.
  59      *  2. Kick off a normal CloudKit fetch.
  60      *  3. Process the incoming queue as normal.
  61      *          (Note that this requires the keybag to be unlocked.)
  62      *
  63      * So far, this is normal operation. Now:
  64      *
  65      *  4. Start another CloudKit fetch, giving it the nil change tag. This fetches all objects in CloudKit.
  66      *    4a. Compare those objects against our local mirror. If any discrepancies, this is a bug.
  67      *    4b. All conflicts: CloudKit data wins.
  68      *    4c. All items we have that CloudKit doesn't: delete locally.
  69      *
  70      *  5. Process the incoming queue again. This should be empty.
  71      *  6. Scan the local keychain for items which exist locally but are not in CloudKit. Upload them.
  72      *  7. If there are any such items in 6, restart the sync.
  73      */
  74
  75     // Promote to strong reference
  76     CKKSKeychainView* ckks = self.ckks;
  77
  78     // Synchronous, on some thread. Get back on the CKKS queue for SQL thread-safety.
  79     [ckks dispatchSync: ^bool{
  80         if(self.cancelled) {
  81             ckksnotice("ckksresync", ckks, "CKKSSynchronizeOperation cancelled, quitting");
  82             return false;
  83         }
  84
  85         ckks.lastSynchronizeOperation = self;
  86
  87         uint32_t steps = 5;
  88
  89         ckksnotice("ckksresync", ckks, "Beginning resynchronize (attempt %u)", self.restartCount);
  90
  91         CKOperationGroup* operationGroup = [CKOperationGroup CKKSGroupWithName:@"ckks-resync"];
  92
  93         // Step 1
  94         CKKSFetchAllRecordZoneChangesOperation* fetchOp = [[CKKSFetchAllRecordZoneChangesOperation alloc] initWithContainer:ckks.container
  95                                                                                                                  fetchClass:ckks.cloudKitClassDependencies.fetchRecordZoneChangesOperationClass
  96                                                                                                                      clients:@[ckks]
  97                                                                                                                fetchReasons:[NSSet setWithObject:CKKSFetchBecauseResync]
  98                                                                                                                  apnsPushes:nil
  99                                                                                                                 forceResync:true
 100                                                                                                            ckoperationGroup:operationGroup];
 101         fetchOp.name = [NSString stringWithFormat: @"resync-step%u-fetch", self.restartCount * steps + 1];
 102         [self runBeforeGroupFinished: fetchOp];
 103
 104         // Step 2
 105         CKKSIncomingQueueOperation* incomingOp = [[CKKSIncomingQueueOperation alloc] initWithCKKSKeychainView:ckks errorOnClassAFailure:true];
 106         incomingOp.name = [NSString stringWithFormat: @"resync-step%u-incoming", self.restartCount * steps + 2];
 107         [incomingOp addSuccessDependency:fetchOp];
 108         [self runBeforeGroupFinished:incomingOp];
 109
 110         // Step 3
 111         CKKSScanLocalItemsOperation* scan = [[CKKSScanLocalItemsOperation alloc] initWithCKKSKeychainView:ckks ckoperationGroup:operationGroup];
 112         scan.name = [NSString stringWithFormat: @"resync-step%u-scan", self.restartCount * steps + 3];
 113         [scan addSuccessDependency: incomingOp];
 114         [self runBeforeGroupFinished: scan];
 115
 116         // Step 4
 117         CKKSOutgoingQueueOperation* outgoingOp = [ckks processOutgoingQueue: operationGroup];
 118         outgoingOp.name = [NSString stringWithFormat: @"resync-step%u-outgoing", self.restartCount * steps + 4];
 119         [self dependOnBeforeGroupFinished:outgoingOp];
 120
 121         // Step 5:
 122         CKKSResultOperation* restart = [[CKKSResultOperation alloc] init];
 123         restart.name = [NSString stringWithFormat: @"resync-step%u-consider-restart", self.restartCount * steps + 5];
 124         [restart addExecutionBlock:^{
 125             STRONGIFY(self);
 126             if(!self) {
 127                 secerror("ckksresync: received callback for released object");
 128                 return;
 129             }
 130
 131             if(scan.recordsFound > 0) {
 132                 if(self.restartCount >= 3) {
 133                     // we've restarted too many times. Fail and stop.
 134                     ckkserror("ckksresync", ckks, "restarted synchronization too often; Failing");
 135                     self.error = [NSError errorWithDomain:@"securityd"
 136                                                          code:2
 137                                                      userInfo:@{NSLocalizedDescriptionKey: @"resynchronization restarted too many times; churn in database?"}];
 138                 } else {
 139                     // restart the sync operation.
 140                     self.restartCount += 1;
 141                     ckkserror("ckksresync", ckks, "restarting synchronization operation due to new local items");
 142                     [self groupStart];
 143                 }
 144             }
 145         }];
 146
 147         [restart addSuccessDependency: outgoingOp];
 148         [self runBeforeGroupFinished: restart];
 149
 150         return true;
 151     }];
 152 }
 153
 154 @end;
 155
 156 #endif