Modification du defaultSecurityDescriptor pour une classe Object

Article
06/13/2023

L’exemple de code suivant récupère le descripteur de sécurité par défaut pour une classe d’objet, ajoute un ACE à la liste dacl, puis définit le descripteur de sécurité modifié sur la classe d’objet.

N’oubliez pas que la modification de schéma est désactivée, par défaut, sur tous les contrôleurs de domaine Windows 2000. Pour activer la modification de schéma sur un contrôleur de domaine particulier, définissez une valeur REG_DWORD nommée « Mise à jour du schéma autorisée » sous la clé de Registre suivante :

HKEY_LOCAL_MACHINE\Système\Currentcontrolset\Services\NTDS\Paramètres

Ajoutez cette valeur si elle n’existe pas déjà. Définissez cette valeur sur 1 pour activer la modification de schéma. Si cette valeur est égale à zéro, la modification du schéma est désactivée. Le composant logiciel enfichable MMC du Gestionnaire de schémas fournit une zone de case activée qui sélectionne ou efface cette clé de Registre.

//  Add msvcrt.dll to your project
//  Add activeds.lib to your project
//  Add adsiid.lib to your project

#include "stdafx.h"
#include <wchar.h>
#include <objbase.h>
#include <activeds.h>
#include <ACLAPI.h>
#include <winnt.h>
#include <Sddl.h>
#include "atlbase.h"
#include "stdio.h"
#include "iads.h"
 
#define _WIN32_WINNT 0x0500
 
HRESULT ModifyDefaultSecurityDescriptor( IADs *pObject );

//  Entry point for the application.
int main(int argc, char *argv[])
{
LPOLESTR szPath = new OLECHAR[MAX_PATH];
LPOLESTR pszBuffer  = new WCHAR[MAX_PATH];
HRESULT hr = S_OK;
IADs *pObject = NULL;
VARIANT var;
 
wprintf(L"This program modifies the default security descriptor of an object class\n");
wprintf(L"Specify the object class:");
#ifdef _MBCS
_getws_s(pszBuffer);
if (!pszBuffer)
    return TRUE;
wcscpy_s(szPath,L"LDAP://cn=");
wcscat_s(szPath,pszBuffer);
wcscat_s(szPath,L",");
#endif _MBCS
 
//  Initialize COM.
CoInitialize(NULL);
 
//  Get rootDSE and the schema container DN. Bind to the
//  current user's domain using current user's security context.
 
hr = ADsOpenObject(L"LDAP://rootDSE",
            NULL,
            NULL,
            ADS_SECURE_AUTHENTICATION, // Use Secure Authentication.
            IID_IADs,
            (void**)&pObject);
 
if (SUCCEEDED(hr)) {
    hr = pObject->Get(CComBSTR("schemaNamingContext"), &var);
    if (SUCCEEDED(hr)) {
        #ifdef _MBCS
        wcscat_s(szPath,var.bstrVal);
        #endif _MBCS
        VariantClear(&var);
        if (pObject) {
            pObject->Release();
            pObject = NULL;
    }
    hr = ADsOpenObject(szPath,
               NULL,
               NULL,
               ADS_SECURE_AUTHENTICATION, //  Use Secure Authentication.
               IID_IADs,
               (void**)&pObject);
    if (SUCCEEDED(hr)) {
        wprintf(L"Modify the default SD for the %s class\n", pszBuffer);
        hr = ModifyDefaultSecurityDescriptor( pObject );
    }
  }
}
 
if (FAILED(hr))
    wprintf(L"Failed with the following HRESULT: 0x%x\n", hr);
 
if (pObject)
    pObject->Release();
 
//  Uninitialize COM.
 
CoUninitialize();
return TRUE;
}    
 
 
HRESULT ModifyDefaultSecurityDescriptor(
                          IADs *pObject
                          )
{
HRESULT hr = E_FAIL;
VARIANT var;
PSECURITY_DESCRIPTOR pSDCNV = NULL;
SECURITY_DESCRIPTOR SD = {0};
DWORD dwSDSize = sizeof(SECURITY_DESCRIPTOR);
PSID pOwnerSID = NULL;
DWORD dwOwnerSIDSize = 0;
PSID pGroupSID = NULL;
DWORD dwGroupSIDSize = 0;
PACL pDACL = NULL;
DWORD dwDACLSize = 0;
PACL pSACL = NULL;
DWORD dwSACLSize = 0;
BOOL bDaclPresent = FALSE;
BOOL bDaclDefaulted = FALSE;
PACL pOldDACL, pNewDACL;
ULONG ulLen;
EXPLICIT_ACCESS ea;
DWORD dwRes;
 
//  Get the default security descriptor. Type should be VT_BSTR.
 
hr = pObject->Get(CComBSTR("defaultSecurityDescriptor"), &var);
if (FAILED(hr) || var.vt!=VT_BSTR ) {
    wprintf(L"Error getting default SD: 0x%x\n", hr );
    goto Cleanup;
}
 
wprintf(L"Old Default SD: %s\n", var.bstrVal);
 
//  Convert the security descriptor string to a security descriptor.
 
if ( ! ConvertStringSecurityDescriptorToSecurityDescriptor (
           var.bstrVal, SDDL_REVISION_1, &pSDCNV, NULL )) {
    wprintf(L"Error converting string security descriptor: %d\n", 
           GetLastError() );
    goto Cleanup;
}
 
//  Convert self-relative security descriptor to absolute.
//  First, get the required buffer sizes.
 
if (! MakeAbsoluteSD(pSDCNV, &SD, &dwSDSize, 
           pDACL, &dwDACLSize, 
           pSACL, &dwSACLSize, 
           pOwnerSID, &dwOwnerSIDSize, 
           pGroupSID, &dwGroupSIDSize) ) {
 
  //  Allocate the buffers.
 
  pDACL = (PACL) GlobalAlloc(GPTR, dwDACLSize);
  pSACL = (PACL) GlobalAlloc(GPTR, dwSACLSize);
  pOwnerSID = (PACL) GlobalAlloc(GPTR, dwOwnerSIDSize);
  pGroupSID = (PACL) GlobalAlloc(GPTR, dwGroupSIDSize);
  if (! (pDACL && pSACL && pOwnerSID && pGroupSID) ) {
    wprintf(L"GlobalAlloc failed: %d\n", GetLastError() );
    goto Cleanup;
  }
 
  //  Perform the conversion.
 
  if (! MakeAbsoluteSD(pSDCNV, &SD, &dwSDSize, pDACL, &dwDACLSize, 
           pSACL, &dwSACLSize, pOwnerSID, &dwOwnerSIDSize, 
           pGroupSID, &dwGroupSIDSize) ) {
    wprintf(L"MakeAbsoluteSD: %d\n", GetLastError() );
    goto Cleanup;
  }
}
 
//  Get the DACL from the security descriptor.
 
if (! GetSecurityDescriptorDacl(&SD, &bDaclPresent, 
                  &pOldDACL, &bDaclDefaulted) ) {
    wprintf(L"GetSecurityDescriptorDacl failed: %d\n", GetLastError() );
    goto Cleanup;
} 
 
//  Initialize an EXPLICIT_ACCESS structure for the new ACE.
//  The ACE grants Everyone the right to read properties.
 
ZeroMemory(&ea, sizeof(EXPLICIT_ACCESS));
ea.grfAccessPermissions = ADS_RIGHT_DS_READ_PROP;
ea.grfAccessMode = GRANT_ACCESS;
ea.grfInheritance= 0;
ea.Trustee.TrusteeForm = TRUSTEE_IS_NAME;
ea.Trustee.ptstrName = TEXT("Everyone");
 
//  Create a new ACL that merges the new ACE into the existing DACL.
 
dwRes = SetEntriesInAcl(1, &ea, pOldDACL, &pNewDACL);
if (ERROR_SUCCESS != dwRes)  {
    wprintf(L"SetEntriesInAcl Error %u\n", dwRes );
    goto Cleanup;
}
 
//  Put the modified DACL into the security descriptor.
 
if (! SetSecurityDescriptorDacl(&SD, TRUE, pNewDACL, FALSE) ) {
    wprintf(L"SetSecurityDescriptorOwner failed: %d\n", 
            GetLastError() );
    goto Cleanup;
} 
 
//  Convert the security descriptor back to string format.
 
VariantClear(&var);
if ( ! ConvertSecurityDescriptorToStringSecurityDescriptor (
        &SD, SDDL_REVISION_1, 
        GROUP_SECURITY_INFORMATION | OWNER_SECURITY_INFORMATION |
        DACL_SECURITY_INFORMATION | SACL_SECURITY_INFORMATION, 
        &var.bstrVal, &ulLen )) {
    wprintf(L"Error converting security descriptor to string: %d\n", 
        GetLastError() );
    goto Cleanup;
}
 
wprintf(L"New default SD: %s\n", var.bstrVal);
V_VT(&var) = VT_BSTR;
 
//  Use Put and SetInfo to set the modified security descriptor.
 
hr = pObject->Put(CComBSTR("defaultSecurityDescriptor"), var);
if (FAILED(hr)) {
    wprintf(L"Error putting default SD: 0x%x\n", hr );
    goto Cleanup;
}
 
hr = pObject->SetInfo();
if (FAILED(hr)) {
    wprintf(L"Error setting default SD: 0x%x\n", hr );
    goto Cleanup;
}
 
Cleanup:
 
VariantClear(&var);
if (pSDCNV) 
    LocalFree(pSDCNV);
if (pDACL) 
    GlobalFree(pDACL);
if (pSACL) 
    GlobalFree(pSACL);
if (pOwnerSID) 
    GlobalFree(pOwnerSID);
if (pGroupSID) 
    GlobalFree(pGroupSID);
if (pNewDACL) 
    LocalFree(pNewDACL);
 
return hr;
}

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Modification du defaultSecurityDescriptor pour une classe Object

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