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https://codeberg.org/ziglang/zig.git
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std.Io.Threaded: implement windows random with \Device\CNG
This commit is contained in:
Andrew Kelley
parent
42ca9e5d8e
commit
2f639a45b4
2 changed files with 125 additions and 97 deletions
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@ -65,7 +65,7 @@ argv0: Argv0,
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environ: Environ,
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null_file: NullFile = .{},
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dev_urandom_fd: dev_urandom_fd_t = if (use_dev_urandom) -1 else {},
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random_file: RandomFile = .{},
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pub const Argv0 = switch (native_os) {
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.openbsd, .haiku => struct {
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@ -152,6 +152,15 @@ pub const NullFile = switch (native_os) {
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},
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};
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pub const RandomFile = switch (native_os) {
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.windows => NullFile,
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else => if (use_dev_urandom) NullFile else struct {
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fn deinit(this: @This()) void {
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_ = this;
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}
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},
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};
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pub const Pid = if (native_os == .linux) enum(posix.pid_t) {
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unknown = 0,
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_,
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@ -586,9 +595,7 @@ const Thread = struct {
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/// Always released when `Status.cancelation` is set to `.parked`.
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futex_waiter: if (use_parking_futex) ?*parking_futex.Waiter else ?noreturn,
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random_buffer: [128]u8,
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/// How many bytes of `random_buffer` are filled.
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random_i: usize,
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csprng: std.Random.DefaultCsprng,
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const Handle = Handle: {
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if (std.Thread.use_pthreads) break :Handle std.c.pthread_t;
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@ -1290,9 +1297,7 @@ pub fn deinit(t: *Threaded) void {
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if (have_sig_pipe) posix.sigaction(.PIPE, &t.old_sig_pipe, null);
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}
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t.null_file.deinit();
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if (use_dev_urandom and t.dev_urandom_fd != -1) {
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posix.close(t.dev_urandom_fd);
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}
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t.random_file.deinit();
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t.* = undefined;
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}
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@ -1321,6 +1326,10 @@ fn worker(t: *Threaded) void {
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}),
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.cancel_protection = .unblocked,
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.futex_waiter = undefined,
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.csprng = .{
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.state = undefined,
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.offset = std.math.maxInt(usize),
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},
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};
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Thread.current = &thread;
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@ -1734,8 +1743,6 @@ const getrandom_use_libc = @TypeOf(posix.system.getrandom) != void and (native_o
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const use_dev_urandom = getrandom_use_libc and native_os == .linux;
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const dev_urandom_fd_t = if (use_dev_urandom) posix.fd_t else void;
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fn async(
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userdata: ?*anyopaque,
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result: []u8,
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@ -13873,6 +13880,62 @@ fn processSpawnWindows(userdata: ?*anyopaque, options: process.SpawnOptions) pro
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};
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}
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fn getCngHandle(t: *Threaded) !windows.HANDLE {
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{
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t.mutex.lock();
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defer t.mutex.unlock();
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if (t.random_file.handle) |handle| return handle;
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}
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const device_path = [_]u16{ '\\', 'D', 'e', 'v', 'i', 'c', 'e', '\\', 'C', 'N', 'G' };
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var nt_name: windows.UNICODE_STRING = .{
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.Length = device_path.len * 2,
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.MaximumLength = 0,
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.Buffer = @constCast(&device_path),
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};
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var fresh_handle: windows.HANDLE = undefined;
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var io_status_block: windows.IO_STATUS_BLOCK = undefined;
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var syscall: Syscall = try .start();
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while (true) switch (windows.ntdll.NtOpenFile(
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&fresh_handle,
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.{
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.STANDARD = .{ .SYNCHRONIZE = true },
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.SPECIFIC = .{ .FILE = .{ .READ_DATA = true } },
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},
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&.{
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.Length = @sizeOf(windows.OBJECT_ATTRIBUTES),
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.RootDirectory = null,
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.ObjectName = &nt_name,
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.Attributes = .{},
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.SecurityDescriptor = null,
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.SecurityQualityOfService = null,
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},
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&io_status_block,
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.VALID_FLAGS,
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.{ .IO = .SYNCHRONOUS_NONALERT },
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)) {
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.SUCCESS => {
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syscall.finish();
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t.mutex.lock(); // Another thread might have won the race.
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defer t.mutex.unlock();
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if (t.random_file.handle) |prev_handle| {
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_ = windows.ntdll.NtClose(fresh_handle);
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return prev_handle;
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} else {
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t.random_file.handle = fresh_handle;
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return fresh_handle;
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}
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},
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.CANCELLED => {
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try syscall.checkCancel();
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continue;
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},
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.OBJECT_NAME_NOT_FOUND => return syscall.fail(error.Unexpected), // Observed on wine 10.0
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else => |status| return syscall.unexpectedNtstatus(status),
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};
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}
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fn getNulHandle(t: *Threaded) !windows.HANDLE {
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{
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t.mutex.lock();
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@ -14959,28 +15022,48 @@ fn random(userdata: ?*anyopaque, buffer: []u8) Io.RandomError!void {
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const t: *Threaded = @ptrCast(@alignCast(userdata));
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if (is_windows) {
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// Call RtlGenRandom() instead of CryptGetRandom() on Windows
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// https://github.com/rust-lang-nursery/rand/issues/111
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// https://bugzilla.mozilla.org/show_bug.cgi?id=504270
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const max_read_size: windows.ULONG = std.math.maxInt(windows.ULONG);
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if (buffer.len == 0) return;
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// ProcessPrng from bcryptprimitives.dll has the following properties:
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// * introduces a dependency on bcryptprimitives.dll, which apparently
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// runs a test suite every time it is loaded
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// * heap allocates a 48-byte buffer, handling failure by returning NO_MEMORY in a BOOL
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// despite the function being documented to always return TRUE
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// * reads from "\\Device\\CNG" which then seeds a per-CPU AES CSPRNG
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// Therefore, that function is avoided in favor of using the device directly.
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const cng_device = try getCngHandle(t);
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var io_status_block: windows.IO_STATUS_BLOCK = undefined;
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var i: usize = 0;
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while (i < buffer.len) {
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const buf = buffer[i..];
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const request_n: windows.ULONG = @min(buf.len, max_read_size);
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const syscall: Syscall = try .start();
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const result = windows.advapi32.RtlGenRandom(buf.ptr, request_n);
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syscall.finish();
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if (result == 0) {
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// `RtlGenRandom` has been observed to fail in situations where
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// the system is under heavy load. Unfortunately, it does not
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// call `SetLastError`, so it is not possible to get more
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// specific error information; it could actually be due to an
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// out-of-memory condition, for example.
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return error.EntropyUnavailable;
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const syscall: Syscall = try .start();
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while (true) {
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const remaining_len = std.math.lossyCast(u32, buffer.len - i);
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switch (windows.ntdll.NtDeviceIoControlFile(
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cng_device,
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null,
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null,
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null,
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&io_status_block,
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windows.IOCTL.KSEC.GEN_RANDOM,
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null,
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0,
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buffer[i..].ptr,
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remaining_len,
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)) {
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.SUCCESS => {
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i += remaining_len;
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if (buffer.len - i == 0) {
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return syscall.finish();
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} else {
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try syscall.checkCancel();
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continue;
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}
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},
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.CANCELLED => {
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try syscall.checkCancel();
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continue;
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},
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else => return syscall.fail(error.EntropyUnavailable),
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}
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i += request_n;
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}
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return;
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}
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if (builtin.link_libc and @TypeOf(posix.system.arc4random_buf) != void) {
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@ -15032,6 +15115,7 @@ fn random(userdata: ?*anyopaque, buffer: []u8) Io.RandomError!void {
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}
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}
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if (buffer.len == 0) return;
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const urandom_fd = try getRandomFd(t);
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var i: usize = 0;
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@ -15066,8 +15150,8 @@ fn getRandomFd(t: *Threaded) posix.fd_t {
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t.mutex.lock();
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defer t.mutex.unlock();
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if (t.dev_urandom_fd == -2) return error.EntropyUnavailable;
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if (t.dev_urandom_fd != -1) return t.dev_urandom_fd;
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if (t.random_file.fd == -2) return error.EntropyUnavailable;
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if (t.random_file.fd != -1) return t.random_file.fd;
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}
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const fd: posix.fd_t = fd: {
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@ -15088,7 +15172,7 @@ fn getRandomFd(t: *Threaded) posix.fd_t {
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},
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else => {
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syscall.endSyscall();
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t.dev_urandom_fd = -2;
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t.random_file.fd = -2;
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return error.EntropyUnavailable;
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},
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}
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@ -15108,14 +15192,14 @@ fn getRandomFd(t: *Threaded) posix.fd_t {
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if (!statx.mask.TYPE) return error.Unexpected;
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t.mutex.lock(); // Another thread might have won the race.
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defer t.mutex.unlock();
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if (t.dev_urandom_fd >= 0) {
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if (t.random_file.fd >= 0) {
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posix.close(fd);
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return t.dev_urandom_fd;
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return t.random_file.fd;
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} else if (!posix.S.ISCHR(statx.mode)) {
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t.dev_urandom_fd = -2;
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t.random_file.fd = -2;
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return error.EntropyUnavailable;
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} else {
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t.dev_urandom_fd = fd;
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t.random_file.fd = fd;
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return fd;
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}
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},
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@ -15124,7 +15208,7 @@ fn getRandomFd(t: *Threaded) posix.fd_t {
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continue;
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},
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else => {
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t.dev_urandom_fd = -2;
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t.random_file.fd = -2;
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return error.EntropyUnavailable;
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},
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}
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@ -15137,14 +15221,14 @@ fn getRandomFd(t: *Threaded) posix.fd_t {
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switch (posix.errno(fstat_sym(fd, &stat))) {
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.SUCCESS => {
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syscall.finish();
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if (t.dev_urandom_fd >= 0) {
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if (t.random_file.fd >= 0) {
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posix.close(fd);
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return t.dev_urandom_fd;
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return t.random_file.fd;
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} else if (!posix.S.ISCHR(stat.mode)) {
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t.dev_urandom_fd = -2;
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t.random_file.fd = -2;
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return error.EntropyUnavailable;
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} else {
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t.dev_urandom_fd = fd;
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t.random_file.fd = fd;
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return fd;
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}
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},
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@ -15153,7 +15237,7 @@ fn getRandomFd(t: *Threaded) posix.fd_t {
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continue;
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},
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else => {
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t.dev_urandom_fd = -2;
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t.random_file.fd = -2;
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return error.EntropyUnavailable;
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},
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}
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@ -2647,62 +2647,6 @@ pub fn SetHandleInformation(h: HANDLE, mask: DWORD, flags: DWORD) SetHandleInfor
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}
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}
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/// An alternate implementation of ProcessPrng from bcryptprimitives.dll
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/// This one has the following differences:
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/// * does not heap allocate `buffer`
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/// * does not introduce a dependency on bcryptprimitives.dll, which apparently
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/// runs a test suite every time it is loaded
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/// * reads buffer.len bytes from "\\Device\\CNG" rather than seeding a per-CPU
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/// AES csprng with 48 bytes.
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pub fn ProcessPrng(buffer: []u8) error{Unexpected}!void {
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const device_path = [_]u16{ '\\', 'D', 'e', 'v', 'i', 'c', 'e', '\\', 'C', 'N', 'G' };
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var nt_name: UNICODE_STRING = .{
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.Length = device_path.len * 2,
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.MaximumLength = 0,
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.Buffer = @constCast(&device_path),
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};
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var cng_device: HANDLE = undefined;
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var io_status_block: IO_STATUS_BLOCK = undefined;
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switch (ntdll.NtOpenFile(
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&cng_device,
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.{
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.STANDARD = .{ .SYNCHRONIZE = true },
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.SPECIFIC = .{ .FILE = .{ .READ_DATA = true } },
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},
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&.{
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.Length = @sizeOf(OBJECT_ATTRIBUTES),
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.RootDirectory = null,
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.ObjectName = &nt_name,
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.Attributes = .{},
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.SecurityDescriptor = null,
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.SecurityQualityOfService = null,
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},
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&io_status_block,
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.VALID_FLAGS,
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.{ .IO = .SYNCHRONOUS_NONALERT },
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)) {
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.SUCCESS => {},
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.OBJECT_NAME_NOT_FOUND => return error.Unexpected, // Observed on wine 10.0
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else => |status| return unexpectedStatus(status),
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}
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defer _ = ntdll.NtClose(cng_device);
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switch (ntdll.NtDeviceIoControlFile(
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cng_device,
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null,
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null,
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null,
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&io_status_block,
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IOCTL.KSEC.GEN_RANDOM,
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null,
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0,
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buffer.ptr,
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@intCast(buffer.len),
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)) {
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.SUCCESS => {},
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else => |status| return unexpectedStatus(status),
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}
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}
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pub const WaitForSingleObjectError = error{
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WaitAbandoned,
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WaitTimeOut,
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