Skip to main content

Security in Assemblies

Code Security is all about allowing and preventing code from running.

The .NET Security Model works by the assemblies each having their own Evidence embedded in the Assembly by the Assembly writer.
When the CLR loads the assembly it then reads and applies this Evidence to a Security model and this in turn returns Permissions, depending on what Permissions are returned will determine is the assembly is permitted to execute or not.
So it's Evidence in (on the assembly) -> Code Groups -> Permissions.

Code Access Security (CAS) is the the mechanism used by .NET to manage all of this. It's function is to process assemblies and determine the runtime permissions they should have, e.g. should they code within a certain assembly be allowed to run or not.

All assemblies have Evidence. As the CLR is loading the assembly it looks at this Evidence and processes it using the current machines .NET Code Group. Depending on where the assembly is being loaded from, the Evidence it has, the Code Group configuration on the current machine; will determine the Permissions that assembly gets.

Evidence: Evidence takes into account the assemblies strong name, publisher. There are 2 types of evidence Host Evidence and Assembly Evidence. Host Evidence is all about where the code is being loaded from, internet, local machine these are identified by URI, Site and Zones (Zones are for non internet)

Code Group: You can group permissions for assemblies i.e. all assemblies that have Internet permissions can do such and such. These are setup on the machine, when the CLR is processing the assemblies Evidence it tries to match the output with a Code Group.

Permissions: FullTrust, Internet. Have special meaning to the CLR, these restrict the access of code to resources, resources such as printers, applications etc.


Labels:

Comments

Post a Comment

Popular posts from this blog

dotNET - Debugging

Debugging with .NET MSIL assemblies Visual Studio and debugging the CLR are different, I'll talk about both. MSIL Assemblies Assemblies compiled with .NET tools such as the CLR compiler are compiled into a file which contains MSIL (Microsoft Intermediate Language). At runtime the contents of the assembly are loaded into the CLR and ran as machine code. When you compile an assembly in debug a PDB file is generated alongside the DLL or EXE you've just created. The link between these 2 files is that the PDB contains the line numbers of the methods and classes as well as the file names of the original source code that created the assembly. When you launch the debugger in Visual Studio the assembly is loaded into the Debugger (similar to the CLR) along with the PDB file. The debugger now uses your PDB file contents to match the running code found in the assembly to locations in source files (hopefully in your present project). CLR CLR Inside Out (msdn magazine) .NET Framework Tools:...
7 comments
Read more

Installer CustomAction, Debugging the CustomAction, InstallState

Custom Action The Custom Action is added to the Setup Project, select the Project node and hit the Custom Action button. This allows you add an Action to a particular phase in the Installation. But first you must create the Custom Action. To Add a Custom Action you must first have a Custom Action created, this is usually in the form of a Installer Class, this should be created in a seperate project, the Installer Class is actually one of the File Templates in the C# Projects. So it's File->New Project and select Visual C# Projects. Then add a Class Library, this will prompt you for the Class Library Types , select "Installer Class". Walkthrough - Creating Custom Action (msdn). Also here's a more comprehensive document on Setup/Installer implementations, it delves into the Registry etc Getting Started with Setup Projects (SimpleTalk). Visual Studio Setup Projects and Custom Actions (Simple Talk). Create your Installer Class and then add it as a Custom Action to the ...
3 comments
Read more

Real-time Web Applications

Your application wants to show live data i.e. data sent from Server back up to the Client instead of the usual which is the Client sending data to the Server via a form submit. There are multiple options, currently the best option is WebSockets. Polling Periodically check the Server for updated data, uses SetInterval in Javascript. The Client sends some information to the Server and wants the Server to send back a response, the response is not immediate so the Client wants to wait for the Server but instead of waiting the Client keeps sending requests to the Server and when something is updated on the Server then the Client updates the UI. ( function poll (){ setTimeout ( function (){ $ . ajax ({ url : "server" , success : function ( data ){ //Update your dashboard gauge salesGauge . setValue ( data . value ); //Setup the next poll recursively poll (); }, dataType : "json" }); }, 30000 ); })(); https://...
Post a Comment
Read more