keychain/ckks/CKKSProcessReceivedKeysOperation.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 <AssertMacros.h>
  25
  26 #import "CKKSKeychainView.h"
  27 #import "CKKSCurrentKeyPointer.h"
  28 #import "CKKSKey.h"
  29 #import "CKKSProcessReceivedKeysOperation.h"
  30 #import "keychain/ckks/CloudKitCategories.h"
  31
  32 #if OCTAGON
  33
  34 @implementation CKKSProcessReceivedKeysOperation
  35
  36 - (instancetype)init {
  37     return nil;
  38 }
  39 - (instancetype)initWithCKKSKeychainView:(CKKSKeychainView*)ckks {
  40     if(self = [super init]) {
  41         _ckks = ckks;
  42     }
  43     return self;
  44 }
  45
  46 - (void) main {
  47     // Synchronous, on some thread. Get back on the CKKS queue for SQL thread-safety.
  48
  49     // Take a strong reference.
  50     CKKSKeychainView* ckks = self.ckks;
  51     if(!ckks) {
  52         secerror("ckkskeys: No CKKS object");
  53         return;
  54     }
  55
  56     if(self.cancelled) {
  57         ckksinfo("ckkskey", ckks, "CKKSProcessReceivedKeysOperation cancelled, quitting");
  58         return;
  59     }
  60
  61     [ckks dispatchSyncWithAccountKeys: ^bool{
  62         if(self.cancelled) {
  63             ckksinfo("ckkskey", ckks, "CKKSProcessReceivedKeysOperation cancelled, quitting");
  64             return false;
  65         }
  66
  67         ckks.lastProcessReceivedKeysOperation = self;
  68
  69         NSError* error = nil;
  70         CKKSKey* tlk = nil;
  71         CKKSKey* topKey = nil;
  72
  73         // The synckeys table contains everything that's in CloudKit, if looked at correctly.
  74         // Updates from CloudKit are marked 'remote'; everything else is 'local'.
  75
  76         // Step 1. Find all remote keys.
  77         NSArray<CKKSKey*>* remoteKeys = [CKKSKey remoteKeys:ckks.zoneID error:&error];
  78         if(!remoteKeys) {
  79             ckkserror("ckkskey", ckks, "couldn't fetch list of remote keys: %@", error);
  80             [ckks _onqueueAdvanceKeyStateMachineToState:SecCKKSZoneKeyStateError withError:error];
  81             return false;
  82         }
  83
  84         if([remoteKeys count] == 0u) {
  85             ckksnotice("ckkskey", ckks, "No remote keys? Quitting.");
  86             // Not a ready state, more of a quizzical one? The key state machine will know what to do.
  87             [ckks _onqueueAdvanceKeyStateMachineToState:SecCKKSZoneKeyStateReady withError:error];
  88             return false;
  89         }
  90
  91         ckksinfo("ckkskey", ckks, "remote keys: %@", remoteKeys);
  92
  93         // current TLK record:
  94         CKKSCurrentKeyPointer* currentTLKPointer    = [CKKSCurrentKeyPointer tryFromDatabase: SecCKKSKeyClassTLK zoneID:ckks.zoneID error:&error];
  95         CKKSCurrentKeyPointer* currentClassAPointer = [CKKSCurrentKeyPointer tryFromDatabase: SecCKKSKeyClassA   zoneID:ckks.zoneID error:&error];
  96         CKKSCurrentKeyPointer* currentClassCPointer = [CKKSCurrentKeyPointer tryFromDatabase: SecCKKSKeyClassC   zoneID:ckks.zoneID error:&error];
  97
  98         // Do these pointers point at anything?
  99         NSError* localerror = nil;
 100         CKKSKey* suggestedTLK    = currentTLKPointer.currentKeyUUID    ? [CKKSKey tryFromDatabaseAnyState:currentTLKPointer.currentKeyUUID    zoneID:ckks.zoneID error:&localerror] : nil;
 101         CKKSKey* suggestedClassA = currentClassAPointer.currentKeyUUID ? [CKKSKey tryFromDatabaseAnyState:currentClassAPointer.currentKeyUUID zoneID:ckks.zoneID error:&localerror] : nil;
 102         CKKSKey* suggestedClassC = currentClassCPointer.currentKeyUUID ? [CKKSKey tryFromDatabaseAnyState:currentClassCPointer.currentKeyUUID zoneID:ckks.zoneID error:&localerror] : nil;
 103
 104         if(!currentTLKPointer || !currentClassAPointer || !currentClassCPointer ||
 105            !currentTLKPointer.currentKeyUUID || !currentClassAPointer.currentKeyUUID || !currentClassCPointer.currentKeyUUID ||
 106            !suggestedTLK || !suggestedClassA || !suggestedClassC) {
 107             ckkserror("ckkskey", ckks, "no current pointer for some keyclass: tlk:%@ a:%@ c:%@ %@ %@",
 108                      currentTLKPointer, currentClassAPointer, currentClassCPointer, error, localerror);
 109             [ckks _onqueueAdvanceKeyStateMachineToState:SecCKKSZoneKeyStateBadCurrentPointers withError:error];
 110             return true;
 111         }
 112
 113         for(CKKSKey* key in remoteKeys) {
 114             // Find the active TLK.
 115             if([key.uuid isEqualToString: currentTLKPointer.currentKeyUUID]) {
 116                 if([key wrapsSelf]) {
 117                     tlk = key;
 118                 } else {
 119                     ckkserror("ckkskey", ckks, "current TLK doesn't wrap itself: %@ %@", key, key.parentKeyUUID);
 120                     [ckks _onqueueAdvanceKeyStateMachineToState:SecCKKSZoneKeyStateUnhealthy withError:error];
 121                     return true;
 122                 }
 123             }
 124         }
 125
 126         if(!tlk) {
 127             ckkserror("ckkskey", ckks, "couldn't find active TLK: %@", currentTLKPointer);
 128             [ckks _onqueueAdvanceKeyStateMachineToState:SecCKKSZoneKeyStateUnhealthy withError:error];
 129             return true;
 130         }
 131
 132         // This key is our proposed TLK. Check with the CKKS object.
 133         if(![ckks _onqueueWithAccountKeysCheckTLK: tlk error: &error]) {
 134             // Was this error "I've never seen that TLK before in my life"? If so, enter the "wait for TLK sync" state.
 135             if(error && [error.domain isEqualToString: @"securityd"] && error.code == errSecItemNotFound) {
 136                 ckksnotice("ckkskey", ckks, "Received a TLK which we don't have in the local keychain(%@). Entering waitfortlk.", tlk);
 137                 [ckks _onqueueAdvanceKeyStateMachineToState:SecCKKSZoneKeyStateWaitForTLK withError:nil];
 138                 return true;
 139             } else if(error && [ckks.lockStateTracker isLockedError:error]) {
 140                 // TODO: _onqueueAdvanceKeyStateMachineToState:SecCKKSZoneKeyStateError should handle this. But, we don't have tests, so, leave this in until 33204154
 141                 ckksnotice("ckkskey", ckks, "Received a TLK(%@), but keybag appears to be locked. Entering a waiting state.", tlk);
 142                 [ckks _onqueueAdvanceKeyStateMachineToState:SecCKKSZoneKeyStateWaitForUnlock withError:nil];
 143                 return true;
 144             } else {
 145                 // Otherwise, something has gone horribly wrong. enter error state.
 146                 ckkserror("ckkskey", ckks, "CKKS claims %@ is not a valid TLK: %@", tlk, error);
 147                 NSError* newError = [NSError errorWithDomain:CKKSErrorDomain code:CKKSInvalidTLK description:@"invalid TLK from CloudKit" underlying:error];
 148                 [ckks _onqueueAdvanceKeyStateMachineToState:SecCKKSZoneKeyStateError withError:newError];
 149                 return true;
 150             }
 151         }
 152
 153         // Ensure that new keys wrap to the TLK.
 154         for(CKKSKey* key in remoteKeys) {
 155             if(key == tlk) {
 156                 continue;
 157             }
 158
 159             topKey = [key topKeyInAnyState:&error];
 160
 161             if(error != nil || ![topKey.uuid isEqual: tlk.uuid]) {
 162                 ckkserror("ckkskey", ckks, "new key %@ is orphaned (%@)", key, error);
 163                 // TODO: possibly re-fetch. Maybe not an actual error state.
 164                 [ckks _onqueueAdvanceKeyStateMachineToState:SecCKKSZoneKeyStateError
 165                                                   withError:[NSError errorWithDomain:CKKSErrorDomain
 166                                                                                 code:CKKSOrphanedKey
 167                                                                          description:[NSString stringWithFormat:@"orphaned key(%@) in hierarchy", topKey]
 168                                                                           underlying:error]];
 169                 return true;
 170
 171             }
 172
 173             // Okay, it wraps to the TLK. Can we unwrap it?
 174             if(![key unwrapViaKeyHierarchy:&error] || error != nil) {
 175                 if(error && [ckks.lockStateTracker isLockedError:error]) {
 176                     ckksnotice("ckkskey", ckks, "Couldn't unwrap new key (%@), but keybag appears to be locked. Entering waitforunlock.", key);
 177                     [ckks _onqueueAdvanceKeyStateMachineToState:SecCKKSZoneKeyStateWaitForUnlock withError:error];
 178                     return true;
 179                 } else {
 180                     ckkserror("ckkskey", ckks, "new key %@ claims to wrap to TLK, but we can't unwrap it: %@", topKey, error);
 181                     [ckks _onqueueAdvanceKeyStateMachineToState:SecCKKSZoneKeyStateError
 182                                                       withError:[NSError errorWithDomain:CKKSErrorDomain
 183                                                                                     code:CKKSOrphanedKey
 184                                                                              description:[NSString stringWithFormat:@"unwrappable key(%@) in hierarchy: %@", topKey, error]
 185                                                                               underlying:error]];
 186                     return true;
 187                 }
 188             }
 189
 190             ckksnotice("ckkskey", ckks, "New key %@ wraps to tlk %@", key, tlk);
 191         }
 192
 193
 194         // We're happy with this key hierarchy. Save it.
 195         for(CKKSKey* key in remoteKeys) {
 196             key.state = SecCKKSProcessedStateLocal;
 197
 198             if([key.uuid isEqualToString: currentClassAPointer.currentKeyUUID] ||
 199                [key.uuid isEqualToString: currentClassCPointer.currentKeyUUID]) {
 200                 [key saveToDatabaseAsOnlyCurrentKeyForClassAndState: &error];
 201             } else {
 202                 [key saveToDatabase: &error];
 203             }
 204
 205             [key saveKeyMaterialToKeychain: &error];
 206
 207             if(error) {
 208                 ckkserror("ckkskey", ckks, "couldn't save newly local key %@ to database: %@", key, error);
 209                 [ckks _onqueueAdvanceKeyStateMachineToState:SecCKKSZoneKeyStateError withError: error];
 210                 return false;
 211             }
 212         }
 213
 214         if(!error) {
 215             ckksnotice("ckkskey", ckks, "Accepted new key hierarchy");
 216             [ckks _onqueueAdvanceKeyStateMachineToState: SecCKKSZoneKeyStateReady withError: nil];
 217         } else {
 218             ckkserror("ckkskey", ckks, "error accepting new key hierarchy: %@", error);
 219             [ckks _onqueueAdvanceKeyStateMachineToState: SecCKKSZoneKeyStateError withError: error];
 220         }
 221         return true;
 222     }];
 223 }
 224
 225 @end;
 226
 227 #endif