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Max Goedjen 2022-10-26 23:53:35 -07:00
parent 158afb210e
commit c0e9c2d39a
No known key found for this signature in database
1 changed files with 75 additions and 85 deletions
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160
Sources/Packages/Sources/SecretAgentKit/Agent.swift
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@ -4,25 +4,6 @@ import OSLog
import SecretKit
import AppKit
enum OpenSSHCertificateError: Error {
case unsupportedType
case parsingFailed
case doesNotExist
}
extension OpenSSHCertificateError: CustomStringConvertible {
public var description: String {
switch self {
case .unsupportedType:
return "The key type was unsupported"
case .parsingFailed:
return "Failed to properly parse the SSH certificate"
case .doesNotExist:
return "Certificate does not exist"
}
}
}
/// The `Agent` is an implementation of an SSH agent. It manages coordination and access between a socket, traces requests, notifies witnesses and passes requests to stores.
public class Agent {
@ -30,14 +11,15 @@ public class Agent {
private let witness: SigningWitness?
private let writer = OpenSSHKeyWriter()
private let requestTracer = SigningRequestTracer()
private let certsPath = (NSHomeDirectory() as NSString).appendingPathComponent("PublicKeys") as String
private let publicKeyFileStoreController = PublicKeyFileStoreController(homeDirectory: NSHomeDirectory())
private let logger = Logger()
/// Initializes an agent with a store list and a witness.
/// - Parameters:
/// - storeList: The `SecretStoreList` to make available.
/// - witness: A witness to notify of requests.
public init(storeList: SecretStoreList, witness: SigningWitness? = nil) {
Logger().debug("Agent is running")
logger.debug("Agent is running")
self.storeList = storeList
self.witness = witness
}
@ -53,16 +35,16 @@ extension Agent {
/// - Return value:
/// - Boolean if data could be read
@discardableResult public func handle(reader: FileHandleReader, writer: FileHandleWriter) -> Bool {
Logger().debug("Agent handling new data")
logger.debug("Agent handling new data")
let data = Data(reader.availableData)
guard data.count > 4 else { return false}
let requestTypeInt = data[4]
guard let requestType = SSHAgent.RequestType(rawValue: requestTypeInt) else {
writer.write(OpenSSHKeyWriter().lengthAndData(of: SSHAgent.ResponseType.agentFailure.data))
Logger().debug("Agent returned \(SSHAgent.ResponseType.agentFailure.debugDescription)")
logger.debug("Agent returned \(SSHAgent.ResponseType.agentFailure.debugDescription)")
return true
}
Logger().debug("Agent handling request of type \(requestType.debugDescription)")
logger.debug("Agent handling request of type \(requestType.debugDescription)")
let subData = Data(data[5...])
let response = handle(requestType: requestType, data: subData, reader: reader)
writer.write(response)
@ -76,17 +58,17 @@ extension Agent {
case .requestIdentities:
response.append(SSHAgent.ResponseType.agentIdentitiesAnswer.data)
response.append(identities())
Logger().debug("Agent returned \(SSHAgent.ResponseType.agentIdentitiesAnswer.debugDescription)")
logger.debug("Agent returned \(SSHAgent.ResponseType.agentIdentitiesAnswer.debugDescription)")
case .signRequest:
let provenance = requestTracer.provenance(from: reader)
response.append(SSHAgent.ResponseType.agentSignResponse.data)
response.append(try sign(data: data, provenance: provenance))
Logger().debug("Agent returned \(SSHAgent.ResponseType.agentSignResponse.debugDescription)")
logger.debug("Agent returned \(SSHAgent.ResponseType.agentSignResponse.debugDescription)")
}
} catch {
response.removeAll()
response.append(SSHAgent.ResponseType.agentFailure.data)
Logger().debug("Agent returned \(SSHAgent.ResponseType.agentFailure.debugDescription)")
logger.debug("Agent returned \(SSHAgent.ResponseType.agentFailure.debugDescription)")
}
let full = OpenSSHKeyWriter().lengthAndData(of: response)
return full
@ -108,9 +90,9 @@ extension Agent {
let keyBlob: Data
let curveData: Data
if let (certBlob, certName) = try? checkForCert(secret: secret) {
keyBlob = certBlob
curveData = certName
if let (certificateData, name) = try? sshCertificateKeyBlobAndName(for: secret) {
keyBlob = certificateData
curveData = name
} else {
keyBlob = writer.data(secret: secret)
curveData = writer.curveType(for: secret.algorithm, length: secret.keySize).data(using: .utf8)!
@ -120,7 +102,7 @@ extension Agent {
keyData.append(writer.lengthAndData(of: curveData))
}
Logger().debug("Agent enumerated \(secrets.count) identities")
logger.debug("Agent enumerated \(secrets.count) identities")
return countData + keyData
}
@ -131,15 +113,17 @@ extension Agent {
/// - Returns: An OpenSSH formatted Data payload containing the signed data response.
func sign(data: Data, provenance: SigningRequestProvenance) throws -> Data {
let reader = OpenSSHReader(data: data)
var hash = reader.readNextChunk()
let payloadHash = reader.readNextChunk()
let hash: Data
// Check if hash is actually an openssh certificate and reconstruct the public key if it is
if let certPublicKey = try? getPublicKeyFromCert(certBlob: hash) {
hash = certPublicKey
if let certificatePublicKey = publicKeyHashFromSSHCertificateHash(payloadHash) {
hash = certificatePublicKey
} else {
hash = payloadHash
}
guard let (store, secret) = secret(matching: hash) else {
Logger().debug("Agent did not have a key matching \(hash as NSData)")
logger.debug("Agent did not have a key matching \(hash as NSData)")
throw AgentError.noMatchingKey
}
@ -193,77 +177,66 @@ extension Agent {
try witness.witness(accessTo: secret, from: store, by: provenance)
}
Logger().debug("Agent signed request")
logger.debug("Agent signed request")
return signedData
}
/// Reconstructs a public key from a ``Data`` object that contains an OpenSSH certificate. Currently only ecdsa certificates are supported
/// Reconstructs a public key from a ``Data``, if that ``Data`` contains an OpenSSH certificate hash. Currently only ecdsa certificates are supported
/// - Parameter certBlock: The openssh certificate to extract the public key from
/// - Returns: A ``Data`` object containing the public key in OpenSSH wire format
func getPublicKeyFromCert(certBlob: Data) throws -> Data {
let reader = OpenSSHReader(data: certBlob)
/// - Returns: A ``Data`` object containing the public key in OpenSSH wire format if the ``Data`` is an OpenSSH certificate hash, otherwise nil.
func publicKeyHashFromSSHCertificateHash(_ hash: Data) -> Data? {
let reader = OpenSSHReader(data: hash)
let certType = String(decoding: reader.readNextChunk(), as: UTF8.self)
switch certType {
case "ecdsa-sha2-nistp256-cert-v01@openssh.com",
"ecdsa-sha2-nistp384-cert-v01@openssh.com",
"ecdsa-sha2-nistp521-cert-v01@openssh.com":
_ = reader.readNextChunk() // nonce
let curveIdentifier = reader.readNextChunk()
let publicKey = reader.readNextChunk()
if let curveType = certType.replacingOccurrences(of: "-cert-v01@openssh.com", with: "").data(using: .utf8) {
return writer.lengthAndData(of: curveType) +
writer.lengthAndData(of: curveIdentifier) +
writer.lengthAndData(of: publicKey)
} else {
throw OpenSSHCertificateError.parsingFailed
}
let curveType = certType.replacingOccurrences(of: "-cert-v01@openssh.com", with: "").data(using: .utf8)!
return writer.lengthAndData(of: curveType) +
writer.lengthAndData(of: curveIdentifier) +
writer.lengthAndData(of: publicKey)
default:
throw OpenSSHCertificateError.unsupportedType
return nil
}
}
/// Attempts to find an OpenSSH Certificate that corresponds to a ``Secret``
/// - Parameter secret: The secret to search for a certificate with
/// - Returns: Two ``Data`` objects containing the certificate and certificate name respectively
func checkForCert(secret: AnySecret) throws -> (Data, Data) {
let minimalHex = writer.openSSHMD5Fingerprint(secret: secret).replacingOccurrences(of: ":", with: "")
let certificatePath = certsPath.appending("/").appending("\(minimalHex)-cert.pub")
if FileManager.default.fileExists(atPath: certificatePath) {
Logger().debug("Found certificate for \(secret.name)")
do {
let certContent = try String(contentsOfFile:certificatePath, encoding: .utf8)
let certElements = certContent.trimmingCharacters(in: .whitespacesAndNewlines).components(separatedBy: " ")
if certElements.count >= 2 {
if let certDecoded = Data(base64Encoded: certElements[1] as String) {
if certElements.count >= 3 {
if let certName = certElements[2].data(using: .utf8) {
return (certDecoded, certName)
} else if let certName = secret.name.data(using: .utf8) {
Logger().info("Certificate for \(secret.name) does not have a name tag, using secret name instead")
return (certDecoded, certName)
} else {
throw OpenSSHCertificateError.parsingFailed
}
}
} else {
Logger().warning("Certificate found for \(secret.name) but failed to decode base64 key")
throw OpenSSHCertificateError.parsingFailed
}
}
} catch {
Logger().warning("Certificate found for \(secret.name) but failed to load")
throw OpenSSHCertificateError.parsingFailed
}
/// - Returns: A (``Data``, ``Data``) tuple containing the certificate and certificate name, respectively.
func sshCertificateKeyBlobAndName(for secret: AnySecret) throws -> (Data, Data) {
let certificatePath = publicKeyFileStoreController.sshCertificatePath(for: secret)
guard FileManager.default.fileExists(atPath: certificatePath) else {
throw OpenSSHCertificateError.doesNotExist
}
logger.debug("Found certificate for \(secret.name)")
let certContent = try String(contentsOfFile:certificatePath, encoding: .utf8)
let certElements = certContent.trimmingCharacters(in: .whitespacesAndNewlines).components(separatedBy: " ")
guard certElements.count >= 3 else {
logger.warning("Certificate found for \(secret.name) but failed to load")
throw OpenSSHCertificateError.parsingFailed
}
guard let certDecoded = Data(base64Encoded: certElements[1] as String) else {
logger.warning("Certificate found for \(secret.name) but failed to decode base64 key")
throw OpenSSHCertificateError.parsingFailed
}
if let certName = certElements[2].data(using: .utf8) {
return (certDecoded, certName)
} else if let certName = secret.name.data(using: .utf8) {
logger.info("Certificate for \(secret.name) does not have a name tag, using secret name instead")
return (certDecoded, certName)
} else {
throw OpenSSHCertificateError.parsingFailed
}
throw OpenSSHCertificateError.doesNotExist
}
}
@ -297,6 +270,23 @@ extension Agent {
case unsupportedKeyType
}
enum OpenSSHCertificateError: LocalizedError {
case unsupportedType
case parsingFailed
case doesNotExist
public var errorDescription: String? {
switch self {
case .unsupportedType:
return "The key type was unsupported"
case .parsingFailed:
return "Failed to properly parse the SSH certificate"
case .doesNotExist:
return "Certificate does not exist"
}
}
}
}
extension SSHAgent.ResponseType {