1 files changed, 116 insertions, 0 deletions
diff --git a/updater/msirunner.go b/updater/msirunner.go
new file mode 100644
index 00000000..d7631706
--- /dev/null
+++ b/updater/msirunner.go
@@ -0,0 +1,116 @@
+/* SPDX-License-Identifier: MIT
+ *
+ * Copyright (C) 2019-2020 WireGuard LLC. All Rights Reserved.
+ */
+
+package updater
+
+import (
+	"crypto/rand"
+	"encoding/hex"
+	"errors"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"syscall"
+	"unsafe"
+
+	"golang.org/x/sys/windows"
+)
+
+type tempFile struct {
+	*os.File
+	originalHandle windows.Handle
+}
+
+func (t *tempFile) ExclusivePath() string {
+	if t.originalHandle != 0 {
+		t.Close() // TODO: sort of a toctou, but msi requires unshared file
+		t.originalHandle = 0
+	}
+	return t.Name()
+}
+
+func (t *tempFile) Delete() error {
+	if t.originalHandle == 0 {
+		name16, err := windows.UTF16PtrFromString(t.Name())
+		if err != nil {
+			return err
+		}
+		return windows.DeleteFile(name16) //TODO: how does this deal with reparse points?
+	}
+	disposition := byte(1)
+	err := windows.SetFileInformationByHandle(t.originalHandle, windows.FileDispositionInfo, &disposition, 1)
+	t.originalHandle = 0
+	t.Close()
+	return err
+}
+
+func runMsi(msi *tempFile, userToken uintptr) error {
+	system32, err := windows.GetSystemDirectory()
+	if err != nil {
+		return err
+	}
+	devNull, err := os.OpenFile(os.DevNull, os.O_RDWR, 0)
+	if err != nil {
+		return err
+	}
+	defer devNull.Close()
+	msiPath := msi.ExclusivePath()
+	attr := &os.ProcAttr{
+		Sys: &syscall.SysProcAttr{
+			Token: syscall.Token(userToken),
+		},
+		Files: []*os.File{devNull, devNull, devNull},
+		Dir:   filepath.Dir(msiPath),
+	}
+	msiexec := filepath.Join(system32, "msiexec.exe")
+	proc, err := os.StartProcess(msiexec, []string{msiexec, "/qb!-", "/i", filepath.Base(msiPath)}, attr)
+	if err != nil {
+		return err
+	}
+	state, err := proc.Wait()
+	if err != nil {
+		return err
+	}
+	if !state.Success() {
+		return &exec.ExitError{ProcessState: state}
+	}
+	return nil
+}
+
+func msiTempFile() (*tempFile, error) {
+	var randBytes [32]byte
+	n, err := rand.Read(randBytes[:])
+	if err != nil {
+		return nil, err
+	}
+	if n != int(len(randBytes)) {
+		return nil, errors.New("Unable to generate random bytes")
+	}
+	sd, err := windows.SecurityDescriptorFromString("O:SYD:PAI(A;;FA;;;SY)(A;;FR;;;BA)")
+	if err != nil {
+		return nil, err
+	}
+	sa := &windows.SecurityAttributes{
+		Length:             uint32(unsafe.Sizeof(windows.SecurityAttributes{})),
+		SecurityDescriptor: sd,
+	}
+	windir, err := windows.GetWindowsDirectory()
+	if err != nil {
+		return nil, err
+	}
+	name := filepath.Join(windir, "Temp", hex.EncodeToString(randBytes[:]))
+	name16 := windows.StringToUTF16Ptr(name)
+	fileHandle, err := windows.CreateFile(name16, windows.GENERIC_WRITE|windows.DELETE, 0, sa, windows.CREATE_NEW, windows.FILE_ATTRIBUTE_TEMPORARY, 0)
+	runtime.KeepAlive(sd)
+	if err != nil {
+		return nil, err
+	}
+	windows.MoveFileEx(name16, nil, windows.MOVEFILE_DELAY_UNTIL_REBOOT)
+	return &tempFile{
+		File:           os.NewFile(uintptr(fileHandle), name),
+		originalHandle: fileHandle,
+	}, nil
+}