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