CA2145: Transparent methods should not be decorated with the SuppressUnmanagedCodeSecurityAttribute

Cause

A transparent method, a method that is marked with the SecuritySafeCriticalAttribute attribute, or a type that contains a method is marked with the SuppressUnmanagedCodeSecurityAttribute attribute.

Rule description

Methods decorated with the SuppressUnmanagedCodeSecurityAttribute attribute have an implicit LinkDemand placed upon any method that calls it. This LinkDemand requires that the calling code be security critical. Marking the method that uses SuppressUnmanagedCodeSecurity with the SecurityCriticalAttribute attribute makes this requirement more obvious for callers of the method.

How to fix violations

To fix a violation of this rule, mark the method or type with the SecurityCriticalAttribute attribute.

When to suppress warnings

Do not suppress a warning from this rule.

Code

using System;
using System.Runtime.InteropServices;
using System.Security;

namespace TransparencyWarningsDemo
{

    public class SafeNativeMethods
    {
        // CA2145 violation - transparent method marked SuppressUnmanagedCodeSecurity.  This should be fixed by
        // marking this method SecurityCritical.
        [DllImport("kernel32.dll", SetLastError = true)]
        [SuppressUnmanagedCodeSecurity]
        [return: MarshalAs(UnmanagedType.Bool)]
        internal static extern bool Beep(uint dwFreq, uint dwDuration);
    }
}