maddnias/sjithook

Simple JIT compiler hook in C#

SJITHook

Simple JIT compiler hook in C#.

Compatibility

It supports both x64 and x86 applications, and supports .NET version from 2.0 to 4.5

How to use

• Add a reference to either SJITHook or SJITHook.Compact
• Determine what .NET version the target assembly is using, and pass the according VTableAddrProvider to JITHook:

    // .NET 2.0->3.5
    var hook = new JITHook<MscorjitAddrProvider>();
    // .NET 4.0->4.5
    var hook = new JITHook<ClrjitAddrProvider>();

• Install the hook, and pass your custom CompileMethod delegate:

    if (hook.Hook(HookedCompileMethod))
        Console.WriteLine("Successfully installed hook!");
            
    private static unsafe int HookedCompileMethod(IntPtr thisPtr, [In] IntPtr corJitInfo,
            [In] Data.CorMethodInfo* methodInfo, Data.CorJitFlag flags,
            [Out] IntPtr nativeEntry, [Out] IntPtr nativeSizeOfCode)
        {
            /*
                Do whatever you want with the parameters here
            */
            return hook.OriginalCompileMethod(thisPtr, corJitInfo, methodInfo, flags, nativeEntry, nativeSizeOfCode);
        }

• Finally uninstall the hook when you're done using it:

    if (hook.UnHook())
        Console.WriteLine("Successfully uninstalled hook!");

Remarks

• SJITHook is simply replacing the entry in CILJit's VTable, and not writing any instructions in the actual compileMethod function.
• You need to enable Unsafe code in your project in order to use SJITHook.

sjithook's Issues

dear sir,is this project thread safe?

dear sir,is this project thread safe?

How to support .NET 4.7.2 and is it injectable

Hello,

Could you explain me quickly how I would do to bring support to .NET 4.7.2 ?

Also, if I want to hook the CompileMethod in another process, would it work to embed it into a dll, and inject this dll. Hook.hook would then be called at loading using this hack( C# equivalent of dllMain).

Thank you :)