keychain/ckks/CKKSLockStateTracker.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 #if OCTAGON
  25
  26 #include <notify.h>
  27 #include <dispatch/dispatch.h>
  28 #include <utilities/SecAKSWrappers.h>
  29
  30 #import "keychain/ckks/CKKS.h"
  31 #import "keychain/ckks/CKKSResultOperation.h"
  32 #import "keychain/ckks/CKKSGroupOperation.h"
  33 #import "keychain/ckks/CKKSLockStateTracker.h"
  34
  35 @interface CKKSLockStateTracker ()
  36 @property (readwrite) bool isLocked;
  37 @property dispatch_queue_t queue;
  38 @property NSOperationQueue* operationQueue;
  39 @property NSHashTable<id<CKKSLockStateNotification>> *observers;
  40
  41 @property (nullable) NSDate* lastUnlockedTime;
  42
  43 @end
  44
  45 @implementation CKKSLockStateTracker
  46
  47 - (instancetype)init {
  48     if((self = [super init])) {
  49         _queue = dispatch_queue_create("lock-state-tracker", DISPATCH_QUEUE_SERIAL);
  50         _operationQueue = [[NSOperationQueue alloc] init];
  51
  52         _isLocked = true;
  53         _observers = [NSHashTable weakObjectsHashTable];
  54         [self resetUnlockDependency];
  55
  56         __weak __typeof(self) weakSelf = self;
  57
  58         // If this is a live server, register with notify
  59         if(!SecCKKSTestsEnabled()) {
  60             int token = 0;
  61             notify_register_dispatch(kUserKeybagStateChangeNotification, &token, _queue, ^(int t) {
  62                 [weakSelf _onqueueRecheck];
  63             });
  64         }
  65
  66         dispatch_async(_queue, ^{
  67             [weakSelf _onqueueRecheck];
  68         });
  69     }
  70     return self;
  71 }
  72
  73 - (NSDate*)lastUnlockTime {
  74     // If unlocked, the last unlock time is now. Otherwise, used the cached value.
  75     __block NSDate* date = nil;
  76     dispatch_sync(self.queue, ^{
  77         if(self.isLocked) {
  78             date = self.lastUnlockedTime;
  79         } else {
  80             date = [NSDate date];
  81             self.lastUnlockedTime = date;
  82         }
  83     });
  84     return date;
  85 }
  86
  87 -(NSString*)description {
  88     return [NSString stringWithFormat: @"<CKKSLockStateTracker: %@ last:%@>",
  89             self.isLocked ? @"locked" : @"unlocked",
  90             self.isLocked ? self.lastUnlockedTime : @"now"];
  91 }
  92
  93 -(void)resetUnlockDependency {
  94     if(self.unlockDependency == nil || ![self.unlockDependency isPending]) {
  95         CKKSResultOperation* op = [CKKSResultOperation named:@"keybag-unlocked-dependency" withBlock: ^{
  96             secinfo("ckks", "Keybag unlocked");
  97         }];
  98         op.descriptionErrorCode = CKKSResultDescriptionPendingUnlock;
  99         self.unlockDependency = op;
 100     }
 101 }
 102
 103 +(bool)queryAKSLocked {
 104     CFErrorRef aksError = NULL;
 105     bool locked = true;
 106
 107     if(!SecAKSGetIsLocked(&locked, &aksError)) {
 108         secerror("ckks: error querying lock state: %@", aksError);
 109         CFReleaseNull(aksError);
 110     }
 111
 112     return locked;
 113 }
 114
 115 -(void)_onqueueRecheck {
 116     dispatch_assert_queue(self.queue);
 117
 118     static bool first = true;
 119     bool wasLocked = self.isLocked;
 120     self.isLocked = [CKKSLockStateTracker queryAKSLocked];
 121
 122     if(wasLocked != self.isLocked || first) {
 123         first = false;
 124         if(self.isLocked) {
 125             // We're locked now.
 126             [self resetUnlockDependency];
 127
 128             if(wasLocked) {
 129                 self.lastUnlockedTime = [NSDate date];
 130             }
 131         } else {
 132             [self.operationQueue addOperation: self.unlockDependency];
 133             self.unlockDependency = nil;
 134             self.lastUnlockedTime = [NSDate date];
 135         }
 136
 137         bool isUnlocked = (self.isLocked == false);
 138         for (id<CKKSLockStateNotification> observer in _observers) {
 139             __strong typeof(observer) strongObserver = observer;
 140             if (strongObserver == NULL)
 141                 return;
 142             dispatch_async(dispatch_get_global_queue(QOS_CLASS_DEFAULT, 0), ^{
 143                 [strongObserver lockStateChangeNotification:isUnlocked];
 144             });
 145         }
 146     }
 147 }
 148
 149 -(void)recheck {
 150     dispatch_sync(self.queue, ^{
 151         [self _onqueueRecheck];
 152     });
 153 }
 154
 155 -(bool)isLockedError:(NSError *)error {
 156     return ([error.domain isEqualToString:@"securityd"] || [error.domain isEqualToString:(__bridge NSString*)kSecErrorDomain])
 157             && error.code == errSecInteractionNotAllowed;
 158 }
 159
 160 -(void)addLockStateObserver:(id<CKKSLockStateNotification>)object
 161 {
 162     dispatch_async(self.queue, ^{
 163         [self->_observers addObject:object];
 164         bool isUnlocked = (self.isLocked == false);
 165         dispatch_async(dispatch_get_global_queue(QOS_CLASS_DEFAULT, 0), ^{
 166             [object lockStateChangeNotification:isUnlocked];
 167         });
 168     });
 169 }
 170
 171
 172 @end
 173
 174 #endif // OCTAGON