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namespace System.Web.Mvc {
using System;
using System.Diagnostics.CodeAnalysis;
using System.Reflection;
using System.Security;
internal static class SecurityUtil {
private static Action<Action> _callInAppTrustThunk;
// !! IMPORTANT !!
// Do not try to optimize this method or perform any extra caching; doing so could lead to MVC not operating
// correctly until the AppDomain is restarted.
[SuppressMessage("Microsoft.Security", "CA2107:ReviewDenyAndPermitOnlyUsage",
Justification = "This is essentially the same logic as Page.ProcessRequest.")]
[SuppressMessage("Microsoft.Design", "CA1031:DoNotCatchGeneralExceptionTypes",
Justification = "If an exception is thrown, assume we're running in same trust level as the application itself, so we don't need to do anything special.")]
private static Action<Action> GetCallInAppTrustThunk() {
// do we need to create the thunk?
if (_callInAppTrustThunk == null) {
try {
if (!typeof(SecurityUtil).Assembly.IsFullyTrusted /* bin-deployed */
|| AppDomain.CurrentDomain.IsHomogenous /* .NET 4 CAS model */) {
// we're already running in the application's trust level, so nothing to do
_callInAppTrustThunk = f => f();
}
else {
// legacy CAS model - need to lower own permission level to be compatible with legacy systems
// This is essentially the same logic as Page.ProcessRequest(HttpContext)
NamedPermissionSet namedPermissionSet = (NamedPermissionSet)typeof(HttpRuntime).GetProperty("NamedPermissionSet", BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Static).GetValue(null, null);
bool disableProcessRequestInApplicationTrust = (bool)typeof(HttpRuntime).GetProperty("DisableProcessRequestInApplicationTrust", BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Static).GetValue(null, null);
if (namedPermissionSet != null && !disableProcessRequestInApplicationTrust) {
_callInAppTrustThunk = f => {
// lower permissions
namedPermissionSet.PermitOnly();
f();
};
}
else {
// application's trust level is FullTrust, so nothing to do
_callInAppTrustThunk = f => f();
}
}
}
catch {
// MVC assembly is already running in application trust, so swallow exceptions
}
}
// if there was an error, just process transparently
return _callInAppTrustThunk ?? (Action<Action>)(f => f());
}
public static TResult ProcessInApplicationTrust<TResult>(Func<TResult> func) {
TResult result = default(TResult);
ProcessInApplicationTrust(delegate { result = func(); });
return result;
}
public static void ProcessInApplicationTrust(Action action) {
Action<Action> executor = GetCallInAppTrustThunk();
executor(action);
}
}
}
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