CKKSProcessReceivedKeysOperation.m   [plain text]

/*
* Copyright (c) 2016 Apple Inc. All Rights Reserved.
*
* @APPLE_LICENSE_HEADER_START@
*
* This file contains Original Code and/or Modifications of Original Code
* as defined in and that are subject to the Apple Public Source License
* Version 2.0 (the 'License'). You may not use this file except in
* compliance with the License. Please obtain a copy of the License at
* http://www.opensource.apple.com/apsl/ and read it before using this
* file.
*
* The Original Code and all software distributed under the License are
* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
* Please see the License for the specific language governing rights and
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* @APPLE_LICENSE_HEADER_END@
*/

#if OCTAGON

#import <AssertMacros.h>

#import "CKKSKeychainView.h"
#import "CKKSCurrentKeyPointer.h"
#import "CKKSKey.h"
#import "CKKSProcessReceivedKeysOperation.h"
#import "keychain/ckks/CKKSOperationDependencies.h"
#import "keychain/ckks/CloudKitCategories.h"
#import "keychain/categories/NSError+UsefulConstructors.h"

@implementation CKKSProcessReceivedKeysOperation
@synthesize intendedState = _intendedState;

- (instancetype)initWithDependencies:(CKKSOperationDependencies*)dependencies
intendedState:(OctagonState*)intendedState
errorState:(OctagonState*)errorState
{
if(self = [super init]) {
_deps = dependencies;
_intendedState = intendedState;
_nextState = errorState;
}
return self;
}

- (void)main {
NSArray<CKKSPeerProviderState*>* currentTrustStates = self.deps.currentTrustStates;

[self.deps.databaseProvider dispatchSyncWithSQLTransaction:^CKKSDatabaseTransactionResult {
bool ok = [self _onqueueMain:currentTrustStates];

return ok ? CKKSDatabaseTransactionCommit : CKKSDatabaseTransactionRollback;
}];
}

- (bool)_onqueueMain:(NSArray<CKKSPeerProviderState*>*)currentTrustStates
{
NSError* error = nil;
CKKSKey* tlk = nil;
CKKSKey* topKey = nil;

// The synckeys table contains everything that's in CloudKit, if looked at correctly.
// Updates from CloudKit are marked 'remote'; everything else is 'local'.

// Step 1. Find all remote keys.
NSArray<CKKSKey*>* remoteKeys = [CKKSKey remoteKeys:self.deps.zoneID error:&error];
if(!remoteKeys) {
ckkserror("ckkskey", self.deps.zoneID, "couldn't fetch list of remote keys: %@", error);
self.error = error;
self.nextState = SecCKKSZoneKeyStateError;
return false;
}

if([remoteKeys count] == 0u) {
ckksnotice("ckkskey", self.deps.zoneID, "No remote keys? Quitting.");
// Not a ready state, more of a quizzical one? The key state machine will know what to do.
self.error = error;
self.nextState = SecCKKSZoneKeyStateBecomeReady;
return false;
}

ckksinfo("ckkskey", self.deps.zoneID, "remote keys: %@", remoteKeys);

// current TLK record:
CKKSCurrentKeyPointer* currentTLKPointer = [CKKSCurrentKeyPointer tryFromDatabase: SecCKKSKeyClassTLK zoneID:self.deps.zoneID error:&error];
CKKSCurrentKeyPointer* currentClassAPointer = [CKKSCurrentKeyPointer tryFromDatabase: SecCKKSKeyClassA zoneID:self.deps.zoneID error:&error];
CKKSCurrentKeyPointer* currentClassCPointer = [CKKSCurrentKeyPointer tryFromDatabase: SecCKKSKeyClassC zoneID:self.deps.zoneID error:&error];

// Do these pointers point at anything?
NSError* localerror = nil;
CKKSKey* suggestedTLK = currentTLKPointer.currentKeyUUID ? [CKKSKey tryFromDatabaseAnyState:currentTLKPointer.currentKeyUUID zoneID:self.deps.zoneID error:&localerror] : nil;
CKKSKey* suggestedClassA = currentClassAPointer.currentKeyUUID ? [CKKSKey tryFromDatabaseAnyState:currentClassAPointer.currentKeyUUID zoneID:self.deps.zoneID error:&localerror] : nil;
CKKSKey* suggestedClassC = currentClassCPointer.currentKeyUUID ? [CKKSKey tryFromDatabaseAnyState:currentClassCPointer.currentKeyUUID zoneID:self.deps.zoneID error:&localerror] : nil;

if(!currentTLKPointer || !currentClassAPointer || !currentClassCPointer ||
!currentTLKPointer.currentKeyUUID || !currentClassAPointer.currentKeyUUID || !currentClassCPointer.currentKeyUUID ||
!suggestedTLK || !suggestedClassA || !suggestedClassC) {
ckkserror("ckkskey", self.deps.zoneID, "no current pointer for some keyclass: tlk:%@ a:%@ c:%@ %@ %@",
currentTLKPointer, currentClassAPointer, currentClassCPointer, error, localerror);
self.error = error;
self.nextState = SecCKKSZoneKeyStateBadCurrentPointers;
return true;
}

for(CKKSKey* key in remoteKeys) {
// Find the active TLK.
if([key.uuid isEqualToString: currentTLKPointer.currentKeyUUID]) {
if([key wrapsSelf]) {
tlk = key;
} else {
NSError *newError = [NSError errorWithDomain:CKKSErrorDomain code:CKKSKeyNotSelfWrapped description:[NSString stringWithFormat: @"current TLK doesn't wrap itself: %@ %@", key, key.parentKeyUUID] underlying:error];
ckkserror("ckkskey", self.deps.zoneID, "%@", error);
self.error = newError;
self.nextState = SecCKKSZoneKeyStateUnhealthy;
return true;
}
}
}

if(!tlk) {
ckkserror("ckkskey", self.deps.zoneID, "couldn't find active TLK: %@", currentTLKPointer);
self.error = error;
self.nextState = SecCKKSZoneKeyStateUnhealthy;
return true;
}

if(![tlk validTLK:&error]) {
// Something has gone horribly wrong. Enter error state.
ckkserror("ckkskey", self.deps.zoneID, "CKKS claims %@ is not a valid TLK: %@", tlk, error);
self.error = [NSError errorWithDomain:CKKSErrorDomain code:CKKSInvalidTLK description:@"invalid TLK from CloudKit" underlying:error];
self.nextState = SecCKKSZoneKeyStateError;
return true;
}

// This key is our proposed TLK.
if(![tlk tlkMaterialPresentOrRecoverableViaTLKShare:currentTrustStates
error:&error]) {
// TLK is valid, but not present locally
if(error && [self.deps.lockStateTracker isLockedError:error]) {
ckksnotice("ckkskey", self.deps.zoneID, "Received a TLK(%@), but keybag appears to be locked. Entering a waiting state.", tlk);
self.nextState = SecCKKSZoneKeyStateWaitForUnlock;
} else {
ckksnotice("ckkskey", self.deps.zoneID, "Received a TLK(%@) which we don't have in the local keychain: %@", tlk, error);
self.error = error;
self.nextState = SecCKKSZoneKeyStateTLKMissing;
}
return true;
}

// Ensure that new keys wrap to the TLK.
for(CKKSKey* key in remoteKeys) {
if(key == tlk) {
continue;
}

topKey = [key topKeyInAnyState:&error];

if(error != nil || ![topKey.uuid isEqual: tlk.uuid]) {
ckkserror("ckkskey", self.deps.zoneID, "new key %@ is orphaned (%@)", key, error);
// TODO: possibly re-fetch. Maybe not an actual error state.
self.error = [NSError errorWithDomain:CKKSErrorDomain
code:CKKSOrphanedKey
description:[NSString stringWithFormat:@"orphaned key(%@) in hierarchy", topKey]
underlying:error];
self.nextState = SecCKKSZoneKeyStateError;
return true;

}

// Okay, it wraps to the TLK. Can we unwrap it?
if(![key unwrapViaKeyHierarchy:&error] || error != nil) {
if(error && [self.deps.lockStateTracker isLockedError:error]) {
ckksnotice("ckkskey", self.deps.zoneID, "Couldn't unwrap new key (%@), but keybag appears to be locked. Entering waitforunlock.", key);
self.error = error;
self.nextState = SecCKKSZoneKeyStateWaitForUnlock;
return true;
} else {
ckkserror("ckkskey", self.deps.zoneID, "new key %@ claims to wrap to TLK, but we can't unwrap it: %@", topKey, error);
self.error = [NSError errorWithDomain:CKKSErrorDomain
code:CKKSOrphanedKey
description:[NSString stringWithFormat:@"unwrappable key(%@) in hierarchy: %@", topKey, error]
underlying:error];
self.nextState = SecCKKSZoneKeyStateError;
return true;
}
}

ckksnotice("ckkskey", self.deps.zoneID, "New key %@ wraps to tlk %@", key, tlk);
}

// We're happy with this key hierarchy. Save it.
for(CKKSKey* key in remoteKeys) {
key.state = SecCKKSProcessedStateLocal;

if([key.uuid isEqualToString: currentClassAPointer.currentKeyUUID] ||
[key.uuid isEqualToString: currentClassCPointer.currentKeyUUID]) {
[key saveToDatabaseAsOnlyCurrentKeyForClassAndState: &error];
} else {
[key saveToDatabase: &error];
}

[key saveKeyMaterialToKeychain: &error];

if(error) {
if([self.deps.lockStateTracker isLockedError:error]) {
ckksnotice("ckkskey", self.deps.zoneID, "Couldn't save newly local key %@ keychain, due to lock state. Entering a waiting state; %@", key, error);
self.nextState = SecCKKSZoneKeyStateWaitForUnlock;
} else {
ckkserror("ckkskey", self.deps.zoneID, "couldn't save newly local key %@ to database: %@", key, error);
self.nextState = SecCKKSZoneKeyStateError;
}
self.error = error;
return false;
}
}

// New key hierarchy? Get it backed up!
// TLKs are now saved in the local keychain; fire off a backup
CKKSNearFutureScheduler* tlkNotifier = self.deps.savedTLKNotifier;
ckksnotice("ckkstlk", self.deps.zoneID, "triggering new TLK notification: %@", tlkNotifier);
[tlkNotifier trigger];

if(!error) {
ckksnotice("ckkskey", self.deps.zoneID, "Accepted new key hierarchy");
self.nextState = self.intendedState;
} else {
ckkserror("ckkskey", self.deps.zoneID, "error accepting new key hierarchy: %@", error);
self.error = error;
self.nextState = SecCKKSZoneKeyStateError;
}
return true;
}

@end;

#endif