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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift open source project
//
// Copyright (c) 2023 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See http://swift.org/LICENSE.txt for license information
// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
import Dispatch
import struct Foundation.Data
import struct Foundation.Date
import struct Foundation.URL
import Basics
#if USE_IMPL_ONLY_IMPORTS
@_implementationOnly import SwiftASN1
@_implementationOnly @_spi(DisableValidityCheck) import X509
#else
import SwiftASN1
@_spi(DisableValidityCheck) import X509
#endif
extension SignatureProviderProtocol {
@PolicyBuilder
func buildPolicySet(configuration: VerifierConfiguration, httpClient: HTTPClient) -> some VerifierPolicy {
_CodeSigningPolicy()
_ADPCertificatePolicy()
let now = Date()
switch (configuration.certificateExpiration, configuration.certificateRevocation) {
case (.enabled(let expiryValidationTime), .strict(let revocationValidationTime)):
RFC5280Policy(validationTime: expiryValidationTime ?? now)
_OCSPVerifierPolicy(
failureMode: .hard,
httpClient: httpClient,
validationTime: revocationValidationTime ?? now
)
case (.enabled(let expiryValidationTime), .allowSoftFail(let revocationValidationTime)):
RFC5280Policy(validationTime: expiryValidationTime ?? now)
_OCSPVerifierPolicy(
failureMode: .soft,
httpClient: httpClient,
validationTime: revocationValidationTime ?? now
)
case (.enabled(let expiryValidationTime), .disabled):
RFC5280Policy(validationTime: expiryValidationTime ?? now)
case (.disabled, .strict(let revocationValidationTime)):
// Always do expiry check (and before) if revocation check is enabled
RFC5280Policy(validationTime: revocationValidationTime ?? now)
_OCSPVerifierPolicy(
failureMode: .hard,
httpClient: httpClient,
validationTime: revocationValidationTime ?? now
)
case (.disabled, .allowSoftFail(let revocationValidationTime)):
// Always do expiry check (and before) if revocation check is enabled
RFC5280Policy(validationTime: revocationValidationTime ?? now)
_OCSPVerifierPolicy(
failureMode: .soft,
httpClient: httpClient,
validationTime: revocationValidationTime ?? now
)
case (.disabled, .disabled):
// We should still do basic certificate validations even if expiry check is disabled
RFC5280Policy.withValidityCheckDisabled()
}
}
}
/// Policy for code signing certificates.
struct _CodeSigningPolicy: VerifierPolicy {
let verifyingCriticalExtensions: [ASN1ObjectIdentifier] = [
ASN1ObjectIdentifier.X509ExtensionID.keyUsage,
ASN1ObjectIdentifier.X509ExtensionID.extendedKeyUsage,
]
func chainMeetsPolicyRequirements(chain: UnverifiedCertificateChain) async -> PolicyEvaluationResult {
let isCodeSigning = (
try? chain.leaf.extensions.extendedKeyUsage?.contains(ExtendedKeyUsage.Usage.codeSigning)
) ??
false
guard isCodeSigning else {
return .failsToMeetPolicy(reason: "Certificate \(chain.leaf) does not have code signing extended key usage")
}
return .meetsPolicy
}
}
/// Policy for ADP certificates.
struct _ADPCertificatePolicy: VerifierPolicy {
/// Include custom marker extensions (which can be critical) so they would not
/// be considered unhandled and cause certificate chain validation to fail.
let verifyingCriticalExtensions: [ASN1ObjectIdentifier] = Self.swiftPackageMarkers
+ Self.developmentMarkers
// Marker extensions for Swift Package certificate
private static let swiftPackageMarkers: [ASN1ObjectIdentifier] = [
// This is not a critical extension but including it just in case
ASN1ObjectIdentifier.NameAttributes.adpSwiftPackageMarker,
]
// Marker extensions for Development certificate (included for testing)
private static let developmentMarkers: [ASN1ObjectIdentifier] = [
[1, 2, 840, 113_635, 100, 6, 1, 2],
[1, 2, 840, 113_635, 100, 6, 1, 12],
]
func chainMeetsPolicyRequirements(chain: UnverifiedCertificateChain) async -> PolicyEvaluationResult {
// Not policing anything here. This policy is mainly for
// listing marker extensions to prevent chain validation
// from failing prematurely.
.meetsPolicy
}
}
struct _OCSPVerifierPolicy: VerifierPolicy {
private static let cacheTTL: DispatchTimeInterval = .seconds(5 * 60)
private let cache = ThreadSafeKeyValueStore<
UnverifiedCertificateChain,
(result: PolicyEvaluationResult, expires: DispatchTime)
>()
private var underlying: OCSPVerifierPolicy<_OCSPRequester>
let verifyingCriticalExtensions: [ASN1ObjectIdentifier] = []
/// Initializes an `_OCSPVerifierPolicy` that caches its results.
///
/// - Parameters:
/// - failureMode: `OCSPFailureMode` that defines policy failure in event of failure.
/// Possible values are `hard` (OCSP request failure and unknown status
/// not allowed) or `soft` (OCSP request failure and unknown status allowed).
/// - httpClient: `HTTPClient` that backs`_OCSPRequester` for making OCSP requests.
/// - validationTime: The time used to decide if the OCSP request is relatively recent. It is
/// considered a failure if the request is too old.
init(failureMode: OCSPFailureMode, httpClient: HTTPClient, validationTime: Date) {
self.underlying = OCSPVerifierPolicy(
failureMode: failureMode,
requester: _OCSPRequester(httpClient: httpClient),
validationTime: validationTime
)
}
mutating func chainMeetsPolicyRequirements(chain: UnverifiedCertificateChain) async -> PolicyEvaluationResult {
// Look for cached result
if let cached = self.cache[chain], cached.expires < .now() {
return cached.result
}
// This makes HTTP requests
let result = await self.underlying.chainMeetsPolicyRequirements(chain: chain)
// Save result to cache
self.cache[chain] = (result: result, expires: .now() + Self.cacheTTL)
return result
}
}
private struct _OCSPRequester: OCSPRequester {
let httpClient: HTTPClient
func query(request: [UInt8], uri: String) async -> OCSPRequesterQueryResult {
guard let url = URL(string: uri), let host = url.host else {
return .terminalError(SwiftOCSPRequesterError.invalidURL(uri))
}
do {
let response = try await self.httpClient.post(
url,
body: Data(request),
headers: [
"Content-Type": "application/ocsp-request",
"Host": host,
]
)
guard response.statusCode == 200 else {
throw SwiftOCSPRequesterError.invalidResponse(statusCode: response.statusCode)
}
guard let responseBody = response.body else {
throw SwiftOCSPRequesterError.emptyResponse
}
return .response(Array(responseBody))
} catch {
return .nonTerminalError(error)
}
}
}
enum SwiftOCSPRequesterError: Error {
case invalidURL(String)
case emptyResponse
case invalidResponse(statusCode: Int)
}
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