In Windows 7 (32 bit), I consistently get error 5 (access denied) when I call ::RegOpenKeyEx on HKEY_LOCAL_MACHINE if I am not running in Administrator mode.
This is my code:
result = ::RegOpenKeyEx(HKEY_LOCAL_MACHINE, _T("SOFTWARE\\MyCompany\\MyApp"), 0, KEY_QUERY_VALUE, &keySoftware)
I am trying to build an app that can be installed for an entire machine as opposed to a specific user. Therefore my installer (which does run in Administrator mode) writes to HKEY_LOCAL_MACHINE, and the installer works fine.
I'd like my app to be able to read the data that my installer has put into the registry. I don't want to change any of the registry data. I have also tried using KEY_READ and KEY_EXECUTE instead of KEY_QUERY_VALUE. But it seems that no matter what I do, I cannot read from HKEY_LOCAL_MACHINE without using an elevated status. What am I missing here?
Your installer needs to adjust the security permissions on your Registry key so that non-admin users are allowed to access it. Have a look at RegSetKeySecurity(), or your installer's equivalent, or any number of command-line tools that are available. You can create a DACL that enables read-only access for the Everyone user group, or for specific user accounts.
Update: since you are using Inno Setup, try this in your Registry setup:
[Registry]
Root: HKLM; Subkey: "Software\MyCompany\MyApp"; Permissions: everyone-read
Or:
[Registry]
Root: HKLM; Subkey: "Software\MyCompany\MyApp"; Permissions: users-read
Your code as I was writing this answer:
result = ::RegOpenKeyEx(HKEY_LOCAL_MACHINE, _T("SOFTWARE\\MyCompany\\MyApp"), 0, KEY_QUERY_VALUE, &keySoftware)
RegOpenKeyEx doesn't support general paths, just direct key names.
To use it you would have to iterate your way down the hierarchy.
SHRegOpenUSKey is one alternative that does support general paths:
HUSKEY keySoftware;
LSTATUS const result = ::SHRegOpenUSKey(
L"Software\\Microsoft\\MediaPlayer", KEY_QUERY_VALUE, 0, &keySoftware, TRUE
);
Related
I've been tasked with updating an old Visual Studio C++ COM executable to work with Visual Studio 2010 and run on 64bit Windows 7. (The program itself is 32bit.)
Part of that process involves making sure registry reads/writes/creates still work and/or updating them to use HKEY_CURRENT_USER rather than HKEY_LOCAL_MACHINE. However, when testing the registry functions which use RegCreateKeyEx, RegQueryValue, RegSetValue, etc. and using ProcessMonitor to watch the registry accesses I noticed some (potentially?) odd behaviour.
When the root is specified as HKEY_CURRENT_USER everything seems to work as expected. For example, when trying to create the key
HKCU\Software\Classes\CLSID\[Guid]
ProcessMonitor will show the following key being created,
HKCU\Software\Classes\Wow6432Node\CLSID\[Guid]
Which is expected (32bit application on 64bit machine).
However, if the root is HKEY_LOCAL_MACHINE when trying to create the key
HKLM\Software\Classes\CLSID\[Guid]
ProcessMonitor will show the following key being created,
HKCR\Wow6432Node\CLSID\[Guid]
Is this expected behaviour? Does it have anything to do with restrictions to writing to HKEY_LOCAL_MACHINE? This is my first time really dealing with registry access, so I'm not familair with any nitty-gritty details. Through some research I've learned that HKEY_CLASSES_ROOT is some kind of amalgemation of HKCU and HKLM, though I'm not sure if that is relevant.
The program is running as Administrator with UAC disabled. The first registry access looks like this, with pszRootKey = 'Software/Classes', and everything else builds off m_hk
dwErr = RegCreateKeyEx(
HKEY_LOCAL_MACHINE, pszRootKey, 0, NULL, 0, KEY_ALL_ACCESS, NULL,
&m_hk, NULL
);
Edit:
When stepping through the code the above call to RegCreateKeyEx() produces the following in ProcessMonitor:
Operation | Path | Result | Detail
---------------------------------------------------------------------------------
RegQueryKey | HKLM | SUCCESS | Query: HandleTags, HandleTags: 0x0
RegCreateKey | HKCR | SUCCESS | Desired Access: All Access, Disposition:REG_OPENED_EXISTING_KEY
RegSetInfoKey | HKCR | SUCCESS | KeySetInformationClass: KeySetHandleTagsInformation, Length: 0
If you run your program with Administrator rights with UAC disabled, this will show your problem is not related to the User Account Control. Instead of this, the problem is very likely to be caused by WOW64. You can find more information about this at these locations:
Registry Redirector
Registry Keys Affected by WOW64
I want to get all the CLSIDs keys that are under the HKEY_CLASSES_ROOT\\SOFTWARE\\Classes\\CLSID key.
I know that that key is mirror for merged HKEY_LOCAL_MACHINE\\SOFTWARE\\Classes\\CLSID and HKEY_CURRENT_USER\\SOFTWARE\\Classes\\CLSID keys.
So far I can enumerate all HKEY_CLASSES_ROOT\\SOFTWARE\\Classes\\CLSID (HKEY_LOCAL_MACHINE\\... and HKEY_CURRENT_USER\\... as well) and get that key's names into std::wstring[]. But when I try to open that keys:
//CLSID = e.g. L"{CAFEEFAC-0013-0001-0001-ABCDEFFEDCBB}"
firstKey = HKEY_LOCAL_MACHINE;
keysPath = L"\\SOFTWARE\\Classes\\CLSID\\"+CLSID;
if(x64System)
regsam = KEY_ALL_ACCESS|KEY_WOW64_64KEY; //on my system
else
regsam = KEY_ALL_ACCESS;
result = RegOpenKeyEx(firstKey, keysPath.c_str(), 0, regsam, &outputKey);
It works only for HKEY_CURRENT_USER, for HKEY_LOCAL_MACHINE it returns ERROR_ACCESS_DENIED. Even when I run my program as administrator (in regedit.exe I can see that key's name is good, if it wouldn't error message would be not found, not ERROR_ACCESS_DENIED anyway).
So what should I do to access that keys? I'm sure that some programs can access that keys. Or at least how to get their default value (it is all I want from them)?
In my program I can only list their names with RegQueryInfoKey but cannot access them with RegOpenKeyEx.
Even as an admin you don't have KEY_ALL_ACCESS on HKLM when UAC is enabled. If you want or need KEY_ALL_ACCESS you Need to run your program elevated.
Reduce your rights to the needed Level. If you only want to read just use KEY_READ!
And take care that you have an embedded manifest, without a manifest you might get access, but tis access is virtualized and you don't get access to the real key.
I have a registry entry I can't seem to read in C++, but it shows up in Regedit.
Using the following C++ snippet:
openResult=RegOpenKeyEx( HKEY_LOCAL_MACHINE, _TEXT("SOFTWARE\\Microsoft\\NET Framework Setup\\NDP\\v4\\Full"), 0, KEY_READ, &root);
readResult1=RegQueryValueEx(root, _TEXT("InstallPath"), NULL, NULL, data1, &size);
readResult2=RegQueryValueEx(root, _TEXT("fake_entry"), NULL, NULL, data2, &size);
I get Error 2, ERROR_FILE_NOT_FOUND for my second RegQueryValueEx() call.
As you can see in the image below, my fake_entry exists.
I created this entry via Regedit.
Microsoft's Registry Keys Affected by WOW64 does not include the location I'm trying to read, and as you can see in the picture below, my fake_entry is not in the Wow6432Node location.
Yes, I understand this isn't a registry location I should be changing. I stumbled upon this as I was debugging my code and am curious why my added fake_entry doesn't work.
Yes, I've read about Registry Redirector.
Yes, I've read this question.
Yes, I tried reading fake_entry at SOFTWARE\\Wow6432Node\\Microsoft\\NET Framework Setup\\NDP\\v4\\Full with the same error.
Running Windows 7, 64 bit, C++ in Visual Studio 2010, using ASCII character encoding.
Am I misunderstanding the Registry Redirector?
Is there a problem with my code?
Are there some sort of permission settings on certain portions of the Registry? I'm obviously missing something. Please point me in the right direction.
Try
openResult = RegOpenKeyEx( HKEY_LOCAL_MACHINE, _TEXT("SOFTWARE\\Microsoft\\NET Framework Setup\\NDP\\v4\\Full"), 0, KEY_READ|KEY_WOW64_64KEY, &root);
according to MSDN you should use either KEY_WOW64_64KEY or KEY_WOW64_32KEY for WOW64 access
You are misreading the table of keys affected by WOW64. From the very top of that page:
The following table lists registry keys that are redirected, shared by both 32-bit and 64-bit applications, or redirected and reflected on 64-bit Windows. Subkeys of the keys in this table inherit the parent key's behavior unless otherwise specified. If a key has no parent listed in this table, the key is shared.
The parent of your key is HKLM\Software which is redirected. So your key is also redirected. It inherits that from its parent, as the documentation that I quoted explains.
You'll need to read the 64 bit view using KEY_WOW64_64KEY.
I need to open up and modify a user's registry key from a 32-bit service (note that the user is not logged in at the time.) I do the following:
//For simplicity error checks are not shown
//I also made sure to enable the following privileges:
// SE_RESTORE_NAME, SE_BACKUP_NAME
//"ntuser.dat" = is the file OS uses to load user's profile
if(RegLoadKey(HKEY_LOCAL_MACHINE, L"Test123", L"C:\\Users\\UserA\\ntuser.dat") == ERROR_SUCCESS)
{
HKEY hKey;
DWORD dwRes = RegOpenKeyEx(HKEY_LOCAL_MACHINE,
L"Test123\\Software\\Classes\\Local Settings\\Software\\Microsoft\\Windows\\CurrentVersion\\TrayNotify"),
NULL, KEY_READ | KEY_WOW64_64KEY, &hKey);
//'dwRes' = is returned as 2, or ERROR_FILE_NOT_FOUND
RegUnLoadKey(HKEY_LOCAL_MACHINE, L"Test123");
}
The problem is that the Software\Classes\Local Settings\Software\Microsoft\Windows\CurrentVersion\TrayNotify key isn't loaded, even though I know that it exists in the actual user profile. I can verify that by loading the user account and by using 64-bit regedit.
I suspect that this has something to do with the Wow64 redirection but I can't seem to understand what am I doing wrong?
EDIT: Added error check for the first API.
I think I got it. Two corrections to my original code:
First off, since Vista I need to load Usrclass.dat file for the classes hive and not ntuser.dat. It kinda makes sense because ntuser.dat is a part of a user's roaming profile and Classes\Local Settings does not fit into the picture well. So here's the location of the Usrclass.dat file, which contains non-roaming user data (mostly COM stuff, but some other settings as well):
%LocalAppData%\Microsoft\Windows\Usrclass.dat
The key to open after the user hive loads is:
Test123\Local Settings\Software\Microsoft\Windows\CurrentVersion\TrayNotify
that is because the original HKCU\Software\Classes is redirected to HKU\<UserSID>_Classes that is stored in the Usrclass.dat file.
I'm modifying an old C++ program to run on Vista. It does not require Admin privileges.
I've changed the code to put logfiles in \ProgramData\MyApp\. These logfiles are written with the stdio functions (fopen, fprintf, fclose).
Here's the problem:
UserA runs the program first, it creates \ProgramData\MyApp\MyLogFile.txt using CreateFile()
UserB runs the program next, it tries to append to MyLogFile.txt and gets access denied.
I tried creating a null SECURITY_DESCRIPTOR and passing that to CreateFile(). That does create a file with "no permissions assigned", but it seems as if the first user to write to the file takes ownership and afterwards all the other non-admin users are out of luck.
It's important that all users share the same logfiles, but it's also important that I change as little code as possible.
Edited to add:
\ProgramData\MyApp is created by a standard Visual Studio installer. (I don't see any place to set directory security.) When it creates \MyApp it grants Users these permissions:
Read & execute
List folder contents
Read
Special permissions
Under Advanced I see that Special permissions includes:
Create files / write data
Create folders / append data
Write attributes
Write extended attributes
+1 to everyone for trying, but eventually I found the answer here:
how to change the ACLs from c++?
I did have to change one line of that solution, from this:
ea[0].grfAccessMode = DENY_ACCESS;
to this:
ea[0].grfAccessMode = GRANT_ACCESS;
Probably that your application uses an installer. When the installer creates your folder "MyApp", assign read/write rights for everyone. This will probably fix your problem. There are different ways of doing this, but it depends on the type of the setup that you use.
Added custom action info.
If after install the folder does not have the required permissions you could add for example a custom action as a visual basic script on the install sequence, that will set the required permissions.
VBS Examble:
Function SetPermissions()
Dim strHomeFolder, strHome, strUser
Dim intRunError, objShell, objFSO
strHomeFolder = "C:\Test"
Set objShell = CreateObject("Wscript.Shell")
Set objFSO = CreateObject("Scripting.FileSystemObject")
If objFSO.FolderExists(strHomeFolder) Then
intRunError = objShell.Run("%COMSPEC% /c Echo Y| cacls " _
& strHomeFolder & " /t /c /g everyone:F ", 2, True)
If intRunError <> 0 Then
Wscript.Echo "Error assigning permissions for user " _
& strUser & " to home folder " & strHomeFolder
End If
End If
End Function
You need to add an allow rule for the user "Everyone" if that is what you truly want.
A null descriptor will defer to the directory's security if memory serves...
You must definetely use CreateFile. See more about security and access rights. I am sure that functions from the standard C library use CreateFile (it can't use anything else on Windows) but with default security parameters which are not helpful in your case.
I tried also to look inside SECURITY_ATTRIBUTES and SECURITY_DESCRIPTOR structures but it's not very easy to understand how to do it, though it may be a chance.