Commit `194ed30825`

xEgoist <egoist@egoistic.dev>

2023-05-05 02:42:27

child_process: Use security attributes while creating handle.

As suggested by @matu3ba, it can be better to use Security Attributes directly while creating the handle instead of creating the handle then setting the handle to inherit. Doing so can prevent potentially leaking to other parallel spawned processes which would inherit the opened `\Device\Null` handle. This change also allows windows.OpenFile to handle when bInheritHandle is set. Note that we are using the same `saAttr`, but since it's taken as a pointer to a const in all calls, it's never mutated, and OpenFile never alters it. This also saves 1 kernel call for setting the handle to inherit.

master

1 parent 41bf816

Changed files (2)

lib

std

windows.zig

child_process.zig

@@ -86,7 +86,10 @@ pub fn OpenFile(sub_path_w: []const u16, options: OpenFileOptions) OpenError!HAN
     var attr = OBJECT_ATTRIBUTES{
         .Length = @sizeOf(OBJECT_ATTRIBUTES),
         .RootDirectory = if (std.fs.path.isAbsoluteWindowsWTF16(sub_path_w)) null else options.dir,
-        .Attributes = 0, // Note we do not use OBJ_CASE_INSENSITIVE here.
+        .Attributes = if (options.sa) |ptr| blk: { // Note we do not use OBJ_CASE_INSENSITIVE here.
+            const inherit: ULONG = if (ptr.bInheritHandle == TRUE) OBJ_INHERIT else 0;
+            break :blk inherit;
+        } else 0,
         .ObjectName = &nt_name,
         .SecurityDescriptor = if (options.sa) |ptr| ptr.lpSecurityDescriptor else null,
         .SecurityQualityOfService = null,

@@ -650,7 +650,7 @@ pub const ChildProcess = struct {
     }
 
     fn spawnWindows(self: *ChildProcess) SpawnError!void {
-        const saAttr = windows.SECURITY_ATTRIBUTES{
+        var saAttr = windows.SECURITY_ATTRIBUTES{
             .nLength = @sizeOf(windows.SECURITY_ATTRIBUTES),
             .bInheritHandle = windows.TRUE,
             .lpSecurityDescriptor = null,
@@ -663,6 +663,7 @@ pub const ChildProcess = struct {
             windows.OpenFile(&[_]u16{ '\\', 'D', 'e', 'v', 'i', 'c', 'e', '\\', 'N', 'u', 'l', 'l' }, .{
                 .access_mask = windows.GENERIC_READ | windows.GENERIC_WRITE | windows.SYNCHRONIZE,
                 .share_access = windows.FILE_SHARE_READ | windows.FILE_SHARE_WRITE,
+                .sa = &saAttr,
                 .creation = windows.OPEN_EXISTING,
                 .io_mode = .blocking,
             }) catch |err| switch (err) {
@@ -680,9 +681,6 @@ pub const ChildProcess = struct {
         defer {
             if (any_ignore) os.close(nul_handle);
         }
-        if (any_ignore) {
-            try windows.SetHandleInformation(nul_handle, windows.HANDLE_FLAG_INHERIT, windows.HANDLE_FLAG_INHERIT);
-        }
 
         var g_hChildStd_IN_Rd: ?windows.HANDLE = null;
         var g_hChildStd_IN_Wr: ?windows.HANDLE = null;

Commit 194ed30825

Commit `194ed30825`