SetSecurityDescriptorDacl

Example

For a sample code snippet demonstrating how to use this function, please refer to the Security Descriptor Sample.

// This is a placeholder for an actual code example.
// Real examples would be much more involved,
// demonstrating the creation of ACLs and Security Descriptors.

#include <windows.h>
#include <aclapi.h>
#include <stdio.h>

// Function to create a simple DACL
BOOL CreateSimpleDacl(PACL* ppAcl) {
    ACL_SIZE_INFORMATION aclSizeInfo;
    DWORD aclBytesNeeded = 0;
    BOOL bRet = FALSE;

    // Calculate the size needed for the ACL
    if (!GetAclInformation(*ppAcl, &aclSizeInfo, sizeof(ACL_SIZE_INFORMATION), AclSizeInformation)) {
        if (GetLastError() == ERROR_INVALID_HANDLE) { // ACL is NULL, we need to create it
            aclBytesNeeded = 1024; // Initial guess, adjust as needed
            *ppAcl = (PACL)HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, aclBytesNeeded);
            if (*ppAcl == NULL) return FALSE;
            if (!InitializeAcl(*ppAcl, aclBytesNeeded, ACL_REVISION)) return FALSE;
            if (!GetAclInformation(*ppAcl, &aclSizeInfo, sizeof(ACL_SIZE_INFORMATION), AclSizeInformation)) return FALSE;
        } else {
            return FALSE;
        }
    }

    // Add an ACE (Access Allowed) for the current user
    // In a real scenario, you'd use LookupAccountName or similar to get SID
    // For demonstration, we'll assume a simple SID structure is available.

    // Placeholder for SID and ACE addition logic
    printf("Placeholder: Adding ACE to DACL.\n");

    bRet = TRUE;
    return bRet;
}


int main() {
    SECURITY_DESCRIPTOR sd;
    ACL dacl;
    PACL pDacl = &dacl;
    BOOL bDaclPresent = FALSE;
    BOOL bDaclDefaulted = FALSE;

    // Initialize the security descriptor
    if (!InitializeSecurityDescriptor(&sd, SECURITY_DESCRIPTOR_REVISION)) {
        fprintf(stderr, "InitializeSecurityDescriptor failed with error %d\n", GetLastError());
        return 1;
    }

    // Prepare a DACL (simplified, requires more complex logic for real use)
    // In a real app, you would typically use AllocateAndInitializeSid, AddAccessAllowedAce, etc.
    // and ensure sufficient memory is allocated for the ACL.
    printf("Attempting to set DACL...\n");

    // For demonstration, let's assume we want to create a DACL
    // A more robust solution would allocate memory for the DACL using HeapAlloc or LocalAlloc.
    // This example uses a stack-allocated ACL for simplicity, which is not recommended for production.
    if (!CreateSimpleDacl(&pDacl)) {
         fprintf(stderr, "Failed to prepare DACL.\n");
         // Clean up if HeapAlloc was used
         if (pDacl != &dacl && pDacl != NULL) HeapFree(GetProcessHeap(), 0, pDacl);
         return 1;
    }

    bDaclPresent = TRUE;
    bDaclDefaulted = FALSE; // Indicate that the DACL is explicitly set

    // Associate the DACL with the security descriptor
    if (!SetSecurityDescriptorDacl(&sd, bDaclPresent, pDacl, bDaclDefaulted)) {
        fprintf(stderr, "SetSecurityDescriptorDacl failed with error %d\n", GetLastError());
        // Clean up if HeapAlloc was used
        if (pDacl != &dacl && pDacl != NULL) HeapFree(GetProcessHeap(), 0, pDacl);
        return 1;
    }

    printf("SetSecurityDescriptorDacl succeeded.\n");

    // In a real application, you would then typically apply this security descriptor
    // to an object using functions like SetKernelObjectSecurity.

    // Clean up allocated memory for DACL if it was dynamically allocated
    if (pDacl != &dacl && pDacl != NULL) {
        HeapFree(GetProcessHeap(), 0, pDacl);
        pDacl = NULL;
    }

    return 0;
}