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Add a way to specify CASE Authenticated Tags in MTRDeviceControllerSt…
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…artupParams (#26038)

Fixes #22597
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@bzbarsky-apple
bzbarsky-apple authored Apr 11, 2023
1 parent 958d646 commit 4c7b35f
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Showing 5 changed files with 272 additions and 19 deletions.
6 changes: 3 additions & 3 deletions src/darwin/Framework/CHIP/MTRCertificates.h
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Original file line number Diff line number Diff line change
Expand Up @@ -91,9 +91,9 @@ NS_ASSUME_NONNULL_BEGIN
* fabricID must be a valid Matter fabric id.
*
* caseAuthenticatedTags may be nil to indicate no CASE Authenticated Tags
* should be used. If caseAuthenticatedTags is not nil, it must have length at
* most 3 and the values in the array are expected to be 32-bit unsigned Case
* Authenticated Tag values.
* should be used. If caseAuthenticatedTags is not nil, it must contain at most
* 3 numbers, which are expected to be 32-bit unsigned Case Authenticated Tag
* values.
*
* On failure returns nil and if "error" is not null sets *error to the relevant
* error.
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32 changes: 28 additions & 4 deletions src/darwin/Framework/CHIP/MTRDeviceController.mm
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Expand Up @@ -302,10 +302,34 @@ - (BOOL)startup:(MTRDeviceControllerStartupParamsInternal *)startupParams
} else {
chip::MutableByteSpan noc(nocBuffer);

chip::CATValues cats = chip::kUndefinedCATs;
if (startupParams.caseAuthenticatedTags != nil) {
unsigned long long tagCount = startupParams.caseAuthenticatedTags.count;
if (tagCount > chip::kMaxSubjectCATAttributeCount) {
MTR_LOG_ERROR("%llu CASE Authenticated Tags cannot be represented in a certificate.", tagCount);
return;
}

size_t tagIndex = 0;
for (NSNumber * boxedTag in startupParams.caseAuthenticatedTags) {
if (!chip::CanCastTo<chip::CASEAuthTag>(boxedTag.unsignedLongLongValue)) {
MTR_LOG_ERROR("0x%llx is not a valid CASE Authenticated Tag value.", boxedTag.unsignedLongLongValue);
return;
}

auto tag = static_cast<chip::CASEAuthTag>(boxedTag.unsignedLongLongValue);
if (!chip::IsValidCASEAuthTag(tag)) {
MTR_LOG_ERROR("0x%" PRIx32 " is not a valid CASE Authenticated Tag value.", tag);
return;
}

cats.values[tagIndex++] = tag;
}
}

if (commissionerParams.operationalKeypair != nullptr) {
errorCode = _operationalCredentialsDelegate->GenerateNOC(startupParams.nodeID.unsignedLongLongValue,
startupParams.fabricID.unsignedLongLongValue, chip::kUndefinedCATs,
commissionerParams.operationalKeypair->Pubkey(), noc);
startupParams.fabricID.unsignedLongLongValue, cats, commissionerParams.operationalKeypair->Pubkey(), noc);

if ([self checkForStartError:errorCode logMsg:kErrorGenerateNOC]) {
return;
Expand All @@ -325,8 +349,8 @@ - (BOOL)startup:(MTRDeviceControllerStartupParamsInternal *)startupParams
return;
}

errorCode = _operationalCredentialsDelegate->GenerateNOC(startupParams.nodeID.unsignedLongLongValue,
startupParams.fabricID.unsignedLongLongValue, chip::kUndefinedCATs, pubKey, noc);
errorCode = _operationalCredentialsDelegate->GenerateNOC(
startupParams.nodeID.unsignedLongLongValue, startupParams.fabricID.unsignedLongLongValue, cats, pubKey, noc);

if ([self checkForStartError:errorCode logMsg:kErrorGenerateNOC]) {
return;
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22 changes: 17 additions & 5 deletions src/darwin/Framework/CHIP/MTRDeviceControllerStartupParams.h
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Original file line number Diff line number Diff line change
Expand Up @@ -127,16 +127,28 @@ NS_ASSUME_NONNULL_BEGIN
*
* ** nodeID is allowed to be nil to indicate that the existing operational node
* id should be used. The existing operational keys will also be used,
* unless operationalKeypair is provided.
* unless operationalKeypair is provided. The existing caseAuthenticatedTags
* will be used.
*
* ** If nodeID is not nil, a new operational certificate will be generated for
* the provided node id (even if that matches the existing node id), using
* either the operationalKeypair if that is provided or a new randomly
* generated operational key.
*
* generated operational key, and using the provided caseAuthenticatedTags.
*/
@property (nonatomic, copy, nullable) NSNumber * nodeID API_AVAILABLE(ios(16.4), macos(13.3), watchos(9.4), tvos(16.4));

/**
* CASE authenticated tags to use for this controller's operational certificate.
*
* Only allowed to be not nil if nodeID is not nil. In particular, if
* operationalCertificate is not nil, must be nil. The provided operational
* certificate will be used as-is.
*
* If not nil, must contain at most 3 numbers, which are expected to be 32-bit
* unsigned Case Authenticated Tag values.
*/
@property (nonatomic, copy, nullable) NSSet<NSNumber *> * caseAuthenticatedTags MTR_NEWLY_AVAILABLE;

/**
* Root certificate, in X.509 DER form, to use.
*
Expand Down Expand Up @@ -219,8 +231,8 @@ NS_ASSUME_NONNULL_BEGIN
*
* If not nil, and if operationalCertificate is nil, a new operational
* certificate will be generated for the given operationalKeypair. The node id
* will for that certificated will be determined as described in the
* documentation for nodeID.
* for that certificate will be determined as described in the documentation for
* nodeID.
*/
@property (nonatomic, strong, nullable) id<MTRKeypair> operationalKeypair;

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42 changes: 35 additions & 7 deletions src/darwin/Framework/CHIP/MTRDeviceControllerStartupParams.mm
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Original file line number Diff line number Diff line change
Expand Up @@ -98,6 +98,7 @@ - (instancetype)initWithParams:(MTRDeviceControllerStartupParams *)params
_ipk = params.ipk;
_vendorID = params.vendorID;
_nodeID = params.nodeID;
_caseAuthenticatedTags = params.caseAuthenticatedTags;
_rootCertificate = params.rootCertificate;
_intermediateCertificate = params.intermediateCertificate;
_operationalCertificate = params.operationalCertificate;
Expand Down Expand Up @@ -190,6 +191,11 @@ - (instancetype)initWithParams:(MTRDeviceControllerStartupParams *)params
return nil;
}

if (self.caseAuthenticatedTags != nil && self.nodeID == nil) {
MTR_LOG_ERROR("caseAuthenticatedTags must be nil if nodeID is nil");
return nil;
}

if (self.operationalCertificate != nil) {
if (self.operationalKeypair == nil) {
MTR_LOG_ERROR("Must have an operational keypair if an operational certificate is provided");
Expand Down Expand Up @@ -266,14 +272,16 @@ - (instancetype)initForExistingFabric:(FabricTable *)fabricTable
if (self.operationalCertificate == nil && self.nodeID == nil) {
self.nodeID = @(fabric->GetNodeId());

// Make sure to preserve caseAuthenticatedTags from the existing certificate.
uint8_t nocBuf[Credentials::kMaxCHIPCertLength];
MutableByteSpan noc(nocBuf);
CHIP_ERROR err = fabricTable->FetchNOCCert(fabric->GetFabricIndex(), noc);
if (err != CHIP_NO_ERROR) {
MTR_LOG_ERROR("Failed to get existing NOC: %s", ErrorStr(err));
return nil;
}

if (self.operationalKeypair == nil) {
uint8_t nocBuf[Credentials::kMaxCHIPCertLength];
MutableByteSpan noc(nocBuf);
CHIP_ERROR err = fabricTable->FetchNOCCert(fabric->GetFabricIndex(), noc);
if (err != CHIP_NO_ERROR) {
MTR_LOG_ERROR("Failed to get existing NOC: %s", ErrorStr(err));
return nil;
}
self.operationalCertificate = MatterCertToX509Data(noc);
if (self.operationalCertificate == nil) {
MTR_LOG_ERROR("Failed to convert TLV NOC to DER X.509: %s", ErrorStr(err));
Expand All @@ -285,6 +293,26 @@ - (instancetype)initForExistingFabric:(FabricTable *)fabricTable
}
}

CATValues cats;
err = Credentials::ExtractCATsFromOpCert(noc, cats);
if (err != CHIP_NO_ERROR) {
MTR_LOG_ERROR("Failed to extract existing CATs: %s", ErrorStr(err));
return nil;
}

auto tagCount = cats.GetNumTagsPresent();
if (tagCount > 0) {
auto * catSet = [[NSMutableSet alloc] initWithCapacity:tagCount];
for (auto & value : cats.values) {
if (value != kUndefinedCAT) {
[catSet addObject:@(value)];
}
}
self.caseAuthenticatedTags = [NSSet setWithSet:catSet];
} else {
self.caseAuthenticatedTags = nil;
}

usingExistingNOC = YES;
}

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189 changes: 189 additions & 0 deletions src/darwin/Framework/CHIPTests/MTRControllerTests.m
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Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,22 @@

static uint16_t kTestVendorId = 0xFFF1u;

static void CheckStoredOpcertCats(id<MTRStorage> storage, uint8_t fabricIndex, NSSet<NSNumber *> * cats)
{
__auto_type * certData = [storage storageDataForKey:[NSString stringWithFormat:@"f/%x/n", fabricIndex]];
XCTAssertNotNil(certData);

__auto_type * info = [[MTRCertificateInfo alloc] initWithTLVBytes:certData];
XCTAssertNotNil(info);

__auto_type * storedCATs = info.subject.caseAuthenticatedTags;
if (cats == nil) {
XCTAssertTrue(storedCATs.count == 0);
} else {
XCTAssertEqualObjects(storedCATs, cats);
}
}

@interface MTRControllerTests : XCTestCase

@end
Expand Down Expand Up @@ -1359,4 +1375,177 @@ - (void)testControllerExternallyProvidedOperationalKey
XCTAssertFalse([factory isRunning]);
}

- (void)testControllerCATs
{
__auto_type * factory = [MTRDeviceControllerFactory sharedInstance];
XCTAssertNotNil(factory);

__auto_type * storage = [[MTRTestStorage alloc] init];
__auto_type * factoryParams = [[MTRDeviceControllerFactoryParams alloc] initWithStorage:storage];
XCTAssertTrue([factory startControllerFactory:factoryParams error:nil]);
XCTAssertTrue([factory isRunning]);

__auto_type * rootKeys = [[MTRTestKeys alloc] init];
XCTAssertNotNil(rootKeys);

__auto_type * params = [[MTRDeviceControllerStartupParams alloc] initWithIPK:rootKeys.ipk fabricID:@(1) nocSigner:rootKeys];
XCTAssertNotNil(params);

params.vendorID = @(kTestVendorId);

//
// Trying to bring up a controller with too-long CATs should fail.
//
__auto_type * tooLongCATs = [NSSet setWithObjects:@(0x10001), @(0x20001), @(0x30001), @(0x40001), nil];
params.caseAuthenticatedTags = tooLongCATs;
MTRDeviceController * controller = [factory createControllerOnExistingFabric:params error:nil];
XCTAssertNil(controller);

//
// Trying to bring up a controller that has an invalid CAT value should
// fail.
//
__auto_type * invalidCATs = [NSSet setWithObjects:@(0x10001), @(0x20001), @(0x0), nil];
params.caseAuthenticatedTags = invalidCATs;
controller = [factory createControllerOnExistingFabric:params error:nil];
XCTAssertNil(controller);

//
// Bring up a controller with valid CATs
//
__auto_type * validCATs = [NSSet setWithObjects:@(0x10001), @(0x20007), @(0x30005), nil];
params.nodeID = @(17);
params.caseAuthenticatedTags = validCATs;
controller = [factory createControllerOnNewFabric:params error:nil];
XCTAssertNotNil(controller);
XCTAssertTrue([controller isRunning]);

// Check that the resulting certificate has the right CATs and node ID
CheckStoredOpcertCats(storage, 1, validCATs);
XCTAssertEqualObjects([controller controllerNodeID], @(17));

[controller shutdown];
XCTAssertFalse([controller isRunning]);

//
// Trying to bring up the same fabric without specifying any node id
// should not allow trying to specify the same CATs.
//
params.nodeID = nil;
params.caseAuthenticatedTags = validCATs;
controller = [factory createControllerOnExistingFabric:params error:nil];
XCTAssertNil(controller);

//
// Trying to bring up the same fabric without specifying any node id
// should not allow trying to specify different CATs.
//
__auto_type * newCATs = [NSSet setWithObjects:@(0x20005), @(0x70009), @(0x80004), nil];
XCTAssertNotEqualObjects(validCATs, newCATs);
params.nodeID = nil;
params.caseAuthenticatedTags = newCATs;
controller = [factory createControllerOnExistingFabric:params error:nil];
XCTAssertNil(controller);

//
// Trying to bring up the same fabric without specifying any node id
// should end up using the existing CATs.
//
params.nodeID = nil;
params.caseAuthenticatedTags = nil;
controller = [factory createControllerOnExistingFabric:params error:nil];
XCTAssertNotNil(controller);
XCTAssertTrue([controller isRunning]);

// Check that the resulting certificate has the right CATs and node ID
CheckStoredOpcertCats(storage, 1, validCATs);
XCTAssertEqualObjects([controller controllerNodeID], @(17));

[controller shutdown];
XCTAssertFalse([controller isRunning]);

//
// Trying to bring up the same fabric without specifying any node id
// should end up using the existing CATs, even if a new
// operational key is specified.
//
__auto_type * operationalKeys = [[MTRTestKeys alloc] init];
XCTAssertNotNil(operationalKeys);
params.nodeID = nil;
params.operationalKeypair = operationalKeys;
params.caseAuthenticatedTags = nil;

controller = [factory createControllerOnExistingFabric:params error:nil];
XCTAssertNotNil(controller);
XCTAssertTrue([controller isRunning]);

// Check that the resulting certificate has the right CATs and node ID
CheckStoredOpcertCats(storage, 1, validCATs);
XCTAssertEqualObjects([controller controllerNodeID], @(17));

[controller shutdown];
XCTAssertFalse([controller isRunning]);

//
// Trying to bring up the same fabric while specifying the node ID, even if
// it's the same one, should pick up the new CATs.
//
params.nodeID = @(17);
params.operationalKeypair = operationalKeys;
params.caseAuthenticatedTags = newCATs;

controller = [factory createControllerOnExistingFabric:params error:nil];
XCTAssertNotNil(controller);
XCTAssertTrue([controller isRunning]);

// Check that the resulting certificate has the right CATs and node ID
CheckStoredOpcertCats(storage, 1, newCATs);
XCTAssertEqualObjects([controller controllerNodeID], @(17));

[controller shutdown];
XCTAssertFalse([controller isRunning]);

//
// Trying to bring up the same fabric while specifying the node ID should
// let us remove CATs altogether.
//
params.nodeID = @(17);
params.operationalKeypair = operationalKeys;
params.caseAuthenticatedTags = nil;

controller = [factory createControllerOnExistingFabric:params error:nil];
XCTAssertNotNil(controller);
XCTAssertTrue([controller isRunning]);

// Check that the resulting certificate has the right CATs and node ID
CheckStoredOpcertCats(storage, 1, nil);
XCTAssertEqualObjects([controller controllerNodeID], @(17));

[controller shutdown];
XCTAssertFalse([controller isRunning]);

//
// Trying to bring up the same fabric with too-long CATs should fail, if we
// are taking the provided CATs into account.
//
params.nodeID = @(17);
params.operationalKeypair = operationalKeys;
params.caseAuthenticatedTags = tooLongCATs;
controller = [factory createControllerOnExistingFabric:params error:nil];
XCTAssertNil(controller);

//
// Trying to bring up the same fabric with invalid CATs should fail, if we
// are taking the provided CATs into account.
//
params.nodeID = @(17);
params.operationalKeypair = operationalKeys;
params.caseAuthenticatedTags = invalidCATs;
controller = [factory createControllerOnExistingFabric:params error:nil];
XCTAssertNil(controller);

[factory stopControllerFactory];
XCTAssertFalse([factory isRunning]);
}

@end

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