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fix: add code signing requirements to xpc connections #206

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fix: add code signing requirements to xpc connections #206

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1 change: 1 addition & 0 deletions Coder-Desktop/Coder-Desktop/XPCInterface.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -36,6 +36,7 @@ import VPNLib
_ = self.connect()
}
logger.info("connecting to \(helperAppMachServiceName)")
connection.setCodeSigningRequirement(SignatureValidator.peerRequirement)
connection.resume()
self.connection = connection
return connection
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2 changes: 2 additions & 0 deletions Coder-Desktop/Coder-DesktopHelper/HelperXPCListeners.swift
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Expand Up @@ -32,6 +32,7 @@ class HelperNEXPCListener: NSObject, NSXPCListenerDelegate, HelperNEXPCInterface
conns.removeAll { $0 == newConnection }
logger.debug("connection interrupted")
}
newConnection.setCodeSigningRequirement(SignatureValidator.peerRequirement)
newConnection.resume()
conns.append(newConnection)
return true
Expand Down Expand Up @@ -149,6 +150,7 @@ class HelperAppXPCListener: NSObject, NSXPCListenerDelegate, HelperAppXPCInterfa
conns.removeAll { $0 == newConnection }
logger.debug("app connection invalidated")
}
newConnection.setCodeSigningRequirement(SignatureValidator.peerRequirement)
newConnection.resume()
conns.append(newConnection)
return true
Expand Down
1 change: 1 addition & 0 deletions Coder-Desktop/VPN/HelperXPCSpeaker.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,7 @@ final class HelperXPCSpeaker: NEXPCInterface, @unchecked Sendable {
connection.interruptionHandler = { [weak self] in
self?.connection = nil
}
connection.setCodeSigningRequirement(SignatureValidator.peerRequirement)
connection.resume()
self.connection = connection
return connection
Expand Down
124 changes: 0 additions & 124 deletions Coder-Desktop/VPNLib/Download.swift
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Original file line number Diff line number Diff line change
@@ -1,130 +1,6 @@
import CryptoKit
import Foundation

public enum ValidationError: Error {
case fileNotFound
case unableToCreateStaticCode
case invalidSignature
case unableToRetrieveInfo
case invalidIdentifier(identifier: String?)
case invalidTeamIdentifier(identifier: String?)
case missingInfoPList
case invalidVersion(version: String?)
case belowMinimumCoderVersion

public var description: String {
switch self {
case .fileNotFound:
"The file does not exist."
case .unableToCreateStaticCode:
"Unable to create a static code object."
case .invalidSignature:
"The file's signature is invalid."
case .unableToRetrieveInfo:
"Unable to retrieve signing information."
case let .invalidIdentifier(identifier):
"Invalid identifier: \(identifier ?? "unknown")."
case let .invalidVersion(version):
"Invalid runtime version: \(version ?? "unknown")."
case let .invalidTeamIdentifier(identifier):
"Invalid team identifier: \(identifier ?? "unknown")."
case .missingInfoPList:
"Info.plist is not embedded within the dylib."
case .belowMinimumCoderVersion:
"""
The Coder deployment must be version \(SignatureValidator.minimumCoderVersion)
or higher to use Coder Desktop.
"""
}
}

public var localizedDescription: String { description }
}

public class SignatureValidator {
// Whilst older dylibs exist, this app assumes v2.20 or later.
public static let minimumCoderVersion = "2.20.0"

private static let expectedName = "CoderVPN"
private static let expectedIdentifier = "com.coder.Coder-Desktop.VPN.dylib"
private static let expectedTeamIdentifier = "4399GN35BJ"

private static let infoIdentifierKey = "CFBundleIdentifier"
private static let infoNameKey = "CFBundleName"
private static let infoShortVersionKey = "CFBundleShortVersionString"

private static let signInfoFlags: SecCSFlags = .init(rawValue: kSecCSSigningInformation)

// `expectedVersion` must be of the form `[0-9]+.[0-9]+.[0-9]+`
public static func validate(path: URL, expectedVersion: String) throws(ValidationError) {
guard FileManager.default.fileExists(atPath: path.path) else {
throw .fileNotFound
}

var staticCode: SecStaticCode?
let status = SecStaticCodeCreateWithPath(path as CFURL, SecCSFlags(), &staticCode)
guard status == errSecSuccess, let code = staticCode else {
throw .unableToCreateStaticCode
}

let validateStatus = SecStaticCodeCheckValidity(code, SecCSFlags(), nil)
guard validateStatus == errSecSuccess else {
throw .invalidSignature
}

var information: CFDictionary?
let infoStatus = SecCodeCopySigningInformation(code, signInfoFlags, &information)
guard infoStatus == errSecSuccess, let info = information as? [String: Any] else {
throw .unableToRetrieveInfo
}

guard let identifier = info[kSecCodeInfoIdentifier as String] as? String,
identifier == expectedIdentifier
else {
throw .invalidIdentifier(identifier: info[kSecCodeInfoIdentifier as String] as? String)
}

guard let teamIdentifier = info[kSecCodeInfoTeamIdentifier as String] as? String,
teamIdentifier == expectedTeamIdentifier
else {
throw .invalidTeamIdentifier(
identifier: info[kSecCodeInfoTeamIdentifier as String] as? String
)
}

guard let infoPlist = info[kSecCodeInfoPList as String] as? [String: AnyObject] else {
throw .missingInfoPList
}

try validateInfo(infoPlist: infoPlist, expectedVersion: expectedVersion)
}

private static func validateInfo(infoPlist: [String: AnyObject], expectedVersion: String) throws(ValidationError) {
guard let plistIdent = infoPlist[infoIdentifierKey] as? String, plistIdent == expectedIdentifier else {
throw .invalidIdentifier(identifier: infoPlist[infoIdentifierKey] as? String)
}

guard let plistName = infoPlist[infoNameKey] as? String, plistName == expectedName else {
throw .invalidIdentifier(identifier: infoPlist[infoNameKey] as? String)
}

// Downloaded dylib must match the version of the server
guard let dylibVersion = infoPlist[infoShortVersionKey] as? String,
expectedVersion == dylibVersion
else {
throw .invalidVersion(version: infoPlist[infoShortVersionKey] as? String)
}

// Downloaded dylib must be at least the minimum Coder server version
guard let dylibVersion = infoPlist[infoShortVersionKey] as? String,
// x.compare(y) is .orderedDescending if x > y
minimumCoderVersion.compare(dylibVersion, options: .numeric) != .orderedDescending
else {
throw .belowMinimumCoderVersion
}
}
}

public func download(
src: URL,
dest: URL,
Expand Down
128 changes: 128 additions & 0 deletions Coder-Desktop/VPNLib/Validate.swift
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Original file line number Diff line number Diff line change
@@ -0,0 +1,128 @@
import Foundation

public enum ValidationError: Error {
case fileNotFound
case unableToCreateStaticCode
case invalidSignature
case unableToRetrieveInfo
case invalidIdentifier(identifier: String?)
case invalidTeamIdentifier(identifier: String?)
case missingInfoPList
case invalidVersion(version: String?)
case belowMinimumCoderVersion

public var description: String {
switch self {
case .fileNotFound:
"The file does not exist."
case .unableToCreateStaticCode:
"Unable to create a static code object."
case .invalidSignature:
"The file's signature is invalid."
case .unableToRetrieveInfo:
"Unable to retrieve signing information."
case let .invalidIdentifier(identifier):
"Invalid identifier: \(identifier ?? "unknown")."
case let .invalidVersion(version):
"Invalid runtime version: \(version ?? "unknown")."
case let .invalidTeamIdentifier(identifier):
"Invalid team identifier: \(identifier ?? "unknown")."
case .missingInfoPList:
"Info.plist is not embedded within the dylib."
case .belowMinimumCoderVersion:
"""
The Coder deployment must be version \(SignatureValidator.minimumCoderVersion)
or higher to use Coder Desktop.
"""
}
}

public var localizedDescription: String { description }
}

public class SignatureValidator {
// Whilst older dylibs exist, this app assumes v2.20 or later.
public static let minimumCoderVersion = "2.20.0"

private static let expectedName = "CoderVPN"
private static let expectedIdentifier = "com.coder.Coder-Desktop.VPN.dylib"
private static let expectedTeamIdentifier = "4399GN35BJ"

private static let infoIdentifierKey = "CFBundleIdentifier"
private static let infoNameKey = "CFBundleName"
private static let infoShortVersionKey = "CFBundleShortVersionString"

private static let signInfoFlags: SecCSFlags = .init(rawValue: kSecCSSigningInformation)

// `expectedVersion` must be of the form `[0-9]+.[0-9]+.[0-9]+`
public static func validate(path: URL, expectedVersion: String) throws(ValidationError) {
guard FileManager.default.fileExists(atPath: path.path) else {
throw .fileNotFound
}

var staticCode: SecStaticCode?
let status = SecStaticCodeCreateWithPath(path as CFURL, SecCSFlags(), &staticCode)
guard status == errSecSuccess, let code = staticCode else {
throw .unableToCreateStaticCode
}

let validateStatus = SecStaticCodeCheckValidity(code, SecCSFlags(), nil)
guard validateStatus == errSecSuccess else {
throw .invalidSignature
}

var information: CFDictionary?
let infoStatus = SecCodeCopySigningInformation(code, signInfoFlags, &information)
guard infoStatus == errSecSuccess, let info = information as? [String: Any] else {
throw .unableToRetrieveInfo
}

guard let identifier = info[kSecCodeInfoIdentifier as String] as? String,
identifier == expectedIdentifier
else {
throw .invalidIdentifier(identifier: info[kSecCodeInfoIdentifier as String] as? String)
}

guard let teamIdentifier = info[kSecCodeInfoTeamIdentifier as String] as? String,
teamIdentifier == expectedTeamIdentifier
else {
throw .invalidTeamIdentifier(
identifier: info[kSecCodeInfoTeamIdentifier as String] as? String
)
}

guard let infoPlist = info[kSecCodeInfoPList as String] as? [String: AnyObject] else {
throw .missingInfoPList
}

try validateInfo(infoPlist: infoPlist, expectedVersion: expectedVersion)
}

public static let peerRequirement = "anchor apple generic" + // Apple-issued certificate chain
" and certificate leaf[subject.OU] = \"" + expectedTeamIdentifier + "\"" // Signed by the Coder team

private static func validateInfo(infoPlist: [String: AnyObject], expectedVersion: String) throws(ValidationError) {
guard let plistIdent = infoPlist[infoIdentifierKey] as? String, plistIdent == expectedIdentifier else {
throw .invalidIdentifier(identifier: infoPlist[infoIdentifierKey] as? String)
}

guard let plistName = infoPlist[infoNameKey] as? String, plistName == expectedName else {
throw .invalidIdentifier(identifier: infoPlist[infoNameKey] as? String)
}

// Downloaded dylib must match the version of the server
guard let dylibVersion = infoPlist[infoShortVersionKey] as? String,
expectedVersion == dylibVersion
else {
throw .invalidVersion(version: infoPlist[infoShortVersionKey] as? String)
}

// Downloaded dylib must be at least the minimum Coder server version
guard let dylibVersion = infoPlist[infoShortVersionKey] as? String,
// x.compare(y) is .orderedDescending if x > y
minimumCoderVersion.compare(dylibVersion, options: .numeric) != .orderedDescending
else {
throw .belowMinimumCoderVersion
}
}
}
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