memmod: register exception handler tables

Otherwise recent WDK binaries fail on ARM64, where an exception handler
is used for trapping an illegal instruction when ARMv8.1 atomics are
being tested for functionality.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

diff --git a/tun/wintun/memmod/memmod_windows.go b/tun/wintun/memmod/memmod_windows.go
index 59450e785ff72c01e13c5818617f6eb67e1467fb..075c03a08ac72d19e33dfa2415b95e086001440c 100644 (file)
--- a/tun/wintun/memmod/memmod_windows.go
+++ b/tun/wintun/memmod/memmod_windows.go
@@ -159,6 +159,16 @@ func (module *Module) finalizeSection(sectionData *sectionFinalizeData) error {
        return nil
 }
 
+var rtlAddFunctionTable = windows.NewLazySystemDLL("ntdll.dll").NewProc("RtlAddFunctionTable")
+
+func (module *Module) registerExceptionHandlers() {
+       directory := module.headerDirectory(IMAGE_DIRECTORY_ENTRY_EXCEPTION)
+       if directory.Size == 0 || directory.VirtualAddress == 0 {
+               return
+       }
+       rtlAddFunctionTable.Call(module.codeBase+uintptr(directory.VirtualAddress), uintptr(directory.Size)/unsafe.Sizeof(IMAGE_RUNTIME_FUNCTION_ENTRY{}), module.codeBase)
+}
+
 func (module *Module) finalizeSections() error {
        sections := module.headers.Sections()
        imageOffset := module.headers.OptionalHeader.imageOffset()
@@ -500,6 +510,9 @@ func LoadLibrary(data []byte) (module *Module, err error) {
                return
        }
 
+       // Register exception tables, if they exist.
+       module.registerExceptionHandlers()
+
        // TLS callbacks are executed BEFORE the main loading.
        module.executeTLS()
 

diff --git a/tun/wintun/memmod/syscall_windows.go b/tun/wintun/memmod/syscall_windows.go
index b79be69e9e0e6a87dbdf626cfbd6dc7609e486bf..a111f92e7a2ddcb452a5a848498c02ae81fcdc28 100644 (file)
--- a/tun/wintun/memmod/syscall_windows.go
+++ b/tun/wintun/memmod/syscall_windows.go
@@ -370,6 +370,12 @@ const (
        IMAGE_GUARD_CF_FUNCTION_TABLE_SIZE_SHIFT       = 28
 )
 
+type IMAGE_RUNTIME_FUNCTION_ENTRY struct {
+       BeginAddress      uint32
+       EndAddress        uint32
+       UnwindInfoAddress uint32
+}
+
 const (
        DLL_PROCESS_ATTACH = 1
        DLL_THREAD_ATTACH  = 2