Files
Termind/Frameworks/TermindRemoteInfrastructure/Security/KeychainSecretStore.swift
T

499 lines
20 KiB
Swift

import Foundation
import Security
import TermindApplication
import TermindDomain
public nonisolated enum KeychainSecretError: LocalizedError {
case status(OSStatus)
case invalidReference
case unexpectedValue
public var errorDescription: String? {
switch self {
case .status(let status):
(SecCopyErrorMessageString(status, nil) as String?)
?? String(localized: "Keychain error \(status)")
case .invalidReference:
String(localized: "The Keychain reference has the wrong credential type.")
case .unexpectedValue:
String(localized: "The Keychain item does not contain the expected credential type.")
}
}
}
/// The Vault's typed secret boundary. Keeping the store behind this small
/// interface lets connection tests prove password/passphrase lifetime rules
/// without depending on a signed Keychain-enabled test host.
/// Typed storage in the macOS Data Protection Keychain. Independent services
/// prevent a damaged reference from reinterpreting one credential as another.
public nonisolated struct KeychainSecretStore: SecretStoring, Sendable {
private static let passwordService = "com.akinokaede.termind.passwords.v1"
private static let softwareKeyService = "com.akinokaede.termind.ssh-software-keys.v1"
private static let enclaveService = "com.akinokaede.termind.secure-enclave-handles.v1"
private let accessGroup: String
public init(accessGroup: String) {
self.accessGroup = accessGroup
}
public func string(for account: String, storage: PasswordStorage) throws -> String? {
try validateStringReference(account)
guard
let data = try data(
for: account, service: Self.passwordService,
synchronizable: storage == .iCloud
)
else { return nil }
guard let value = String(data: data, encoding: .utf8) else {
throw KeychainSecretError.unexpectedValue
}
return value
}
public func containsString(for account: String, storage: PasswordStorage) throws -> Bool {
try validateStringReference(account)
return try contains(
account, service: Self.passwordService,
synchronizable: storage == .iCloud
)
}
public func sshSecret(for account: String, storage: PasswordStorage) throws -> SSHSecret? {
try validateStringReference(account)
guard
var data = try data(
for: account, service: Self.passwordService,
synchronizable: storage == .iCloud
)
else { return nil }
return SSHSecret(consumingUTF8: &data)
}
public func setString(_ value: String?, for account: String, storage: PasswordStorage) throws {
try validateStringReference(account)
var data = value?.data(using: .utf8)
defer {
if data != nil { SecretMemory.clear(&data!) }
}
try setData(
data, for: account, service: Self.passwordService,
synchronizable: storage == .iCloud,
accessible: storage == .iCloud
? kSecAttrAccessibleWhenUnlocked
: kSecAttrAccessibleWhenUnlockedThisDeviceOnly
)
}
public func keyCredential(for account: String, storage: KeyStorage) throws
-> StoredSSHKeyCredential?
{
try validate(account, prefix: "termind.key.")
guard
var data = try data(
for: account, service: service(for: storage),
synchronizable: storage == .iCloud
)
else { return nil }
defer { SecretMemory.clear(&data) }
switch storage {
case .external:
throw KeychainSecretError.unexpectedValue
case .thisDevice, .iCloud:
return .software(try JSONDecoder().decode(SSHPrivateKeySecret.self, from: data))
case .secureEnclave:
guard !data.isEmpty else { throw KeychainSecretError.unexpectedValue }
return .secureEnclave(SecureEnclaveKeyCredential(dataRepresentation: data))
}
}
public func containsKeyCredential(for account: String, storage: KeyStorage) throws -> Bool {
try validate(account, prefix: "termind.key.")
return try contains(
account, service: service(for: storage),
synchronizable: storage == .iCloud
)
}
public func sshKeyCredential(
for account: String, storage: KeyStorage
) throws -> SSHResolvedKeyCredential? {
try validate(account, prefix: "termind.key.")
guard
var data = try data(
for: account, service: service(for: storage),
synchronizable: storage == .iCloud
)
else { return nil }
defer { SecretMemory.clear(&data) }
switch storage {
case .external:
throw KeychainSecretError.unexpectedValue
case .thisDevice, .iCloud:
return try Self.decodeKeySecrets(from: &data)
case .secureEnclave:
guard !data.isEmpty else { throw KeychainSecretError.unexpectedValue }
return .secureEnclave(SecureEnclaveKeyCredential(dataRepresentation: data))
}
}
public func setKeyCredential(
_ value: StoredSSHKeyCredential?, for account: String, storage: KeyStorage
) throws {
try validate(account, prefix: "termind.key.")
var data: Data?
switch (value, storage) {
case (.software(let secret), .thisDevice), (.software(let secret), .iCloud):
data = try JSONEncoder().encode(secret)
case (.secureEnclave(let credential), .secureEnclave):
data = credential.dataRepresentation
case (nil, _):
data = nil
default:
throw KeychainSecretError.unexpectedValue
}
defer {
if data != nil { SecretMemory.clear(&data!) }
}
try setData(
data, for: account, service: service(for: storage),
synchronizable: storage == .iCloud,
accessible: storage == .iCloud
? kSecAttrAccessibleWhenUnlocked
: kSecAttrAccessibleWhenUnlockedThisDeviceOnly
)
}
public func setResolvedKeyCredential(
_ credential: SSHResolvedKeyCredential, for account: String, storage: KeyStorage
) throws {
defer { credential.clearSecrets() }
try validate(account, prefix: "termind.key.")
var encoded: Data
switch (credential, storage) {
case (.software(let key, let passphrase), .thisDevice), (.software(let key, let passphrase), .iCloud):
encoded = try Self.encodeKeySecrets(privateKey: key, passphrase: passphrase)
case (.secureEnclave(let key), .secureEnclave): encoded = key.dataRepresentation
default: throw KeychainSecretError.unexpectedValue
}
defer { SecretMemory.clear(&encoded) }
try setData(
encoded, for: account, service: service(for: storage), synchronizable: storage == .iCloud,
accessible: storage == .iCloud
? kSecAttrAccessibleWhenUnlocked : kSecAttrAccessibleWhenUnlockedThisDeviceOnly
)
}
public func setKeyPassphrase(_ passphrase: SSHSecret?, for account: String, storage: KeyStorage) throws {
defer { passphrase?.clear() }
guard storage != .secureEnclave,
let credential = try sshKeyCredential(for: account, storage: storage),
case .software(let privateKey, _) = credential
else { throw KeychainSecretError.unexpectedValue }
defer { credential.clearSecrets() }
var encoded = try Self.encodeKeySecrets(privateKey: privateKey, passphrase: passphrase)
defer { SecretMemory.clear(&encoded) }
try setData(
encoded, for: account, service: service(for: storage), synchronizable: storage == .iCloud,
accessible: storage == .iCloud
? kSecAttrAccessibleWhenUnlocked : kSecAttrAccessibleWhenUnlockedThisDeviceOnly
)
}
/// The editor's legacy envelope and the runtime reader share the same wire
/// format. Secret values never become immutable Strings in the runtime path.
static func encodeKeySecrets(privateKey: SSHSecret, passphrase: SSHSecret?) throws -> Data {
defer {
privateKey.clear()
passphrase?.clear()
}
var output = Data()
var succeeded = false
defer { if !succeeded { SecretMemory.clear(&output) } }
func append(_ secret: SSHSecret) throws {
output.append(0x22)
try secret.withUnsafeCStringAndConsume { pointer, count in
for byte in UnsafeRawBufferPointer(start: pointer, count: count) {
switch byte {
case 0x22, 0x5C: output.append(contentsOf: [0x5C, byte])
case 0..<0x20:
let digits = Array("0123456789abcdef".utf8)
output.append(contentsOf: [
0x5C, 0x75, 0x30, 0x30, digits[Int(byte >> 4)], digits[Int(byte & 15)],
])
default: output.append(byte)
}
}
}
output.append(0x22)
}
// Reserve an upper bound before writing any plaintext, avoiding Data
// reallocation while appending escaped secret bytes.
output.reserveCapacity(64 + 6 * (privateKey.byteCount + (passphrase?.byteCount ?? 0)))
output.append(contentsOf: "{\"privateKey\":".utf8)
try append(privateKey)
if let passphrase {
output.append(contentsOf: ",\"passphrase\":".utf8)
try append(passphrase)
}
output.append(0x7D)
succeeded = true
return output
}
static func decodePrivateKeySecret(from data: inout Data) throws -> SSHSecret {
let credential = try decodeKeySecrets(from: &data)
guard case .software(let key, let passphrase) = credential else {
throw KeychainSecretError.unexpectedValue
}
passphrase?.clear()
return key
}
static func decodeKeySecrets(
from data: inout Data, observeSecret: ((SSHSecret) -> Void)? = nil
) throws -> SSHResolvedKeyCredential {
defer { SecretMemory.clear(&data) }
var index = data.startIndex
var privateKey: SSHSecret?
var passphrase: SSHSecret?
var succeeded = false
defer {
if !succeeded {
privateKey?.clear()
passphrase?.clear()
}
}
func skipWhitespace() {
while index < data.endIndex, [0x20, 0x09, 0x0A, 0x0D].contains(data[index]) { index += 1 }
}
func consume(_ expected: UInt8) throws {
guard index < data.endIndex, data[index] == expected else { throw KeychainSecretError.unexpectedValue }
index += 1
}
func hexUnit() throws -> UInt32 {
var value: UInt32 = 0
for _ in 0..<4 {
guard index < data.endIndex else { throw KeychainSecretError.unexpectedValue }
let byte = data[index]
let digit: UInt8
switch byte {
case 0x30...0x39: digit = byte - 0x30
case 0x41...0x46: digit = byte - 0x41 + 10
case 0x61...0x66: digit = byte - 0x61 + 10
default: throw KeychainSecretError.unexpectedValue
}
value = value * 16 + UInt32(digit)
index += 1
}
return value
}
func readString() throws -> SSHSecret {
try consume(0x22)
var bytes = Data()
bytes.reserveCapacity(data.count)
defer { SecretMemory.clear(&bytes) }
while index < data.endIndex {
let byte = data[index]
index += 1
if byte == 0x22 {
func validateUTF8() throws {
var decoder = Unicode.UTF8()
var iterator = bytes.makeIterator()
while true {
switch decoder.decode(&iterator) {
case .scalarValue: continue
case .emptyInput: return
case .error: throw KeychainSecretError.unexpectedValue
}
}
}
try validateUTF8()
let secret = SSHSecret(consumingUTF8: &bytes)
observeSecret?(secret)
return secret
}
guard byte == 0x5C else {
guard byte >= 0x20 else { throw KeychainSecretError.unexpectedValue }
bytes.append(byte)
continue
}
guard index < data.endIndex else { throw KeychainSecretError.unexpectedValue }
let escape = data[index]
index += 1
switch escape {
case 0x22, 0x5C, 0x2F: bytes.append(escape)
case 0x62: bytes.append(0x08)
case 0x66: bytes.append(0x0C)
case 0x6E: bytes.append(0x0A)
case 0x72: bytes.append(0x0D)
case 0x74: bytes.append(0x09)
case 0x75:
var scalar = try hexUnit()
if (0xD800...0xDBFF).contains(scalar) {
try consume(0x5C)
try consume(0x75)
let low = try hexUnit()
guard (0xDC00...0xDFFF).contains(low) else { throw KeychainSecretError.unexpectedValue }
scalar = 0x10000 + ((scalar - 0xD800) << 10) + low - 0xDC00
}
guard let value = Unicode.Scalar(scalar) else { throw KeychainSecretError.unexpectedValue }
Unicode.UTF8.encode(value) { bytes.append($0) }
default: throw KeychainSecretError.unexpectedValue
}
}
throw KeychainSecretError.unexpectedValue
}
skipWhitespace()
try consume(0x7B)
var sawPassphrase = false
while true {
skipWhitespace()
let name = try readString()
defer { name.clear() }
skipWhitespace()
try consume(0x3A)
skipWhitespace()
if name.matches("privateKey"), privateKey == nil {
privateKey = try readString()
} else if name.matches("passphrase"), !sawPassphrase {
sawPassphrase = true
if index < data.endIndex, data[index] == 0x6E {
for byte in Array("null".utf8) { try consume(byte) }
} else {
passphrase = try readString()
if passphrase?.byteCount == 0 {
passphrase?.clear()
passphrase = nil
}
}
} else {
throw KeychainSecretError.unexpectedValue
}
skipWhitespace()
if index < data.endIndex, data[index] == 0x2C {
index += 1
continue
}
try consume(0x7D)
skipWhitespace()
guard index == data.endIndex, let privateKey else { throw KeychainSecretError.unexpectedValue }
succeeded = true
return .software(privateKey, passphrase: passphrase)
}
}
public func removePassword(
_ account: String, storage: PasswordStorage = .thisDevice
) throws {
guard !account.isEmpty else { return }
try validate(account, prefix: "termind.password.")
try remove(
account, service: Self.passwordService,
synchronizable: storage == .iCloud
)
}
public func removeKeyCredential(_ account: String, storage: KeyStorage) throws {
guard !account.isEmpty else { return }
try validate(account, prefix: "termind.key.")
try remove(
account, service: service(for: storage),
synchronizable: storage == .iCloud
)
}
private func data(for account: String, service: String, synchronizable: Bool) throws
-> Data?
{
guard !account.isEmpty else { return nil }
var query = baseQuery(account, service: service, synchronizable: synchronizable)
query[kSecMatchLimit as String] = kSecMatchLimitOne
query[kSecReturnData as String] = true
var result: CFTypeRef?
let status = SecItemCopyMatching(query as CFDictionary, &result)
if status == errSecItemNotFound { return nil }
guard status == errSecSuccess else { throw KeychainSecretError.status(status) }
guard let data = result as? Data else { throw KeychainSecretError.unexpectedValue }
return data
}
private func contains(_ account: String, service: String, synchronizable: Bool) throws -> Bool {
guard !account.isEmpty else { return false }
var query = baseQuery(account, service: service, synchronizable: synchronizable)
query[kSecMatchLimit as String] = kSecMatchLimitOne
query[kSecReturnAttributes as String] = true
var result: CFTypeRef?
let status = SecItemCopyMatching(query as CFDictionary, &result)
if status == errSecItemNotFound { return false }
guard status == errSecSuccess else { throw KeychainSecretError.status(status) }
return true
}
private func setData(
_ value: Data?, for account: String, service: String,
synchronizable: Bool, accessible: CFString
) throws {
guard let value else {
try remove(account, service: service, synchronizable: synchronizable)
return
}
let match = baseQuery(account, service: service, synchronizable: synchronizable)
let attributes: [String: Any] = [
kSecValueData as String: value,
kSecAttrAccessible as String: accessible,
]
let updateStatus = SecItemUpdate(match as CFDictionary, attributes as CFDictionary)
if updateStatus == errSecSuccess { return }
guard updateStatus == errSecItemNotFound else {
throw KeychainSecretError.status(updateStatus)
}
var add = match
for (key, value) in attributes { add[key] = value }
let addStatus = SecItemAdd(add as CFDictionary, nil)
guard addStatus == errSecSuccess else { throw KeychainSecretError.status(addStatus) }
}
private func remove(_ account: String, service: String, synchronizable: Bool) throws {
let query = baseQuery(account, service: service, synchronizable: synchronizable)
let status = SecItemDelete(query as CFDictionary)
guard status == errSecSuccess || status == errSecItemNotFound else {
throw KeychainSecretError.status(status)
}
}
private func baseQuery(
_ account: String, service: String, synchronizable: Bool
) -> [String: Any] {
[
kSecClass as String: kSecClassGenericPassword,
kSecAttrService as String: service,
kSecAttrAccount as String: account,
kSecAttrAccessGroup as String: accessGroup,
kSecAttrSynchronizable as String: synchronizable,
kSecUseDataProtectionKeychain as String: true,
]
}
private func service(for storage: KeyStorage) throws -> String {
switch storage {
case .external:
throw KeychainSecretError.unexpectedValue
case .thisDevice, .iCloud: Self.softwareKeyService
case .secureEnclave: Self.enclaveService
}
}
private func validate(_ account: String, prefix: String) throws {
guard account.hasPrefix(prefix), account.count > prefix.count else {
throw KeychainSecretError.invalidReference
}
}
private func validateStringReference(_ account: String) throws {
let prefixes = ["termind.password.", "termind.ai."]
guard prefixes.contains(where: { account.hasPrefix($0) && account.count > $0.count })
else { throw KeychainSecretError.invalidReference }
}
}