RegLoadAppKey working fine on 32-bit OS, failing on 64-bit OS, even if both processes are 32-bit
- by James Manning
I'm using .NET 4 and the new RegistryKey.FromHandle call so I can take the hKey I get from opening a registry file with RegLoadAppKey and operate on it with the existing managed API.
I thought at first it was just a matter of a busted DllImport and my call had an invalid type in the params or a missing MarshalAs or whatever, but looking at other registry functions and their DllImport declarations (for instance, on pinvoke.net), I don't see what else to try (I've had hKey returned as both int and IntPtr, both worked on 32-bit OS and fail on 64-bit OS)
I've got it down to as simple a repro case as I can - it just tries to create a 'random' subkey then write a value to it. It works fine on my Win7 x86 box and fails on Win7 x64 and 2008 R2 x64, even when it's still a 32-bit process, even run from a 32-bit cmd prompt. EDIT: It also fails in the same way if it's a 64-bit process.
on Win7 x86:
INFO: Running as Admin in 32-bit process on 32-bit OS
Was able to create Microsoft\Windows\CurrentVersion\RunOnceEx\a95b1bbf-7a04-4707-bcca-6aee6afbfab7 and write a value under it
on Win7 x64, as 32-bit:
INFO: Running as Admin in 32-bit process on 64-bit OS
Unhandled Exception: System.UnauthorizedAccessException: Access to the registry key '\Microsoft\Windows\CurrentVersion\RunOnceEx\ce6d5ff6-c3af-47f7-b3dc-c5a1b9a3cd22' is denied.
at Microsoft.Win32.RegistryKey.Win32Error(Int32 errorCode, String str)
at Microsoft.Win32.RegistryKey.CreateSubKeyInternal(String subkey, RegistryKeyPermissionCheck permissionCheck, Object registrySecurityObj, RegistryOptions registryOptions)
at Microsoft.Win32.RegistryKey.CreateSubKey(String subkey)
at LoadAppKeyAndModify.Program.Main(String[] args)
on Win7 x64, as 64-bit:
INFO: Running as Admin in 64-bit process on 64-bit OS
Unhandled Exception: System.UnauthorizedAccessException: Access to the registry key '\Microsoft\Windows\CurrentVersion\RunOnceEx\43bc857d-7d07-499c-8070-574d6732c130' is denied.
at Microsoft.Win32.RegistryKey.Win32Error(Int32 errorCode, String str)
at Microsoft.Win32.RegistryKey.CreateSubKeyInternal(String subkey, RegistryKeyPermissionCheck permissionCheck, Object registrySecurityObj, RegistryOptions registryOptions)
at Microsoft.Win32.RegistryKey.CreateSubKey(String subkey, RegistryKeyPermissionCheck permissionCheck)
at LoadAppKeyAndModify.Program.Main(String[] args)
source:
class Program
{
static void Main(string[] args)
{
Console.WriteLine("INFO: Running as {0} in {1}-bit process on {2}-bit OS",
new WindowsPrincipal(WindowsIdentity.GetCurrent()).IsInRole(WindowsBuiltInRole.Administrator) ? "Admin" : "Normal User",
Environment.Is64BitProcess ? 64 : 32,
Environment.Is64BitOperatingSystem ? 64 : 32);
if (args.Length != 1)
{
throw new ApplicationException("Need 1 argument - path to the software hive file on disk");
}
string softwareHiveFile = Path.GetFullPath(args[0]);
if (File.Exists(softwareHiveFile) == false)
{
throw new ApplicationException("Specified file does not exist: " + softwareHiveFile);
}
// pick a random subkey so it doesn't already exist
var keyPathToCreate = "Microsoft\\Windows\\CurrentVersion\\RunOnceEx\\" + Guid.NewGuid();
var hKey = RegistryNativeMethods.RegLoadAppKey(softwareHiveFile);
using (var safeRegistryHandle = new SafeRegistryHandle(new IntPtr(hKey), true))
using (var appKey = RegistryKey.FromHandle(safeRegistryHandle))
using (var runOnceExKey = appKey.CreateSubKey(keyPathToCreate))
{
runOnceExKey.SetValue("foo", "bar");
Console.WriteLine("Was able to create {0} and write a value under it", keyPathToCreate);
}
}
}
internal static class RegistryNativeMethods
{
[Flags]
public enum RegSAM
{
AllAccess = 0x000f003f
}
private const int REG_PROCESS_APPKEY = 0x00000001;
// approximated from pinvoke.net's RegLoadKey and RegOpenKey
// NOTE: changed return from long to int so we could do Win32Exception on it
[DllImport("advapi32.dll", SetLastError = true)]
private static extern int RegLoadAppKey(String hiveFile, out int hKey, RegSAM samDesired, int options, int reserved);
public static int RegLoadAppKey(String hiveFile)
{
int hKey;
int rc = RegLoadAppKey(hiveFile, out hKey, RegSAM.AllAccess, REG_PROCESS_APPKEY, 0);
if (rc != 0)
{
throw new Win32Exception(rc, "Failed during RegLoadAppKey of file " + hiveFile);
}
return hKey;
}
}
