From 64d98f8ee037282c35007b64c2649055c56af1db Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Wed, 17 Apr 2024 14:19:03 +0200 Subject: Merging upstream version 1.68.2+dfsg1. Signed-off-by: Daniel Baumann --- library/std/src/sys/windows/rand.rs | 121 ++++++++---------------------------- 1 file changed, 27 insertions(+), 94 deletions(-) (limited to 'library/std/src/sys/windows/rand.rs') diff --git a/library/std/src/sys/windows/rand.rs b/library/std/src/sys/windows/rand.rs index b5a49489d..cdf37cfe9 100644 --- a/library/std/src/sys/windows/rand.rs +++ b/library/std/src/sys/windows/rand.rs @@ -1,106 +1,39 @@ -//! # Random key generation -//! -//! This module wraps the RNG provided by the OS. There are a few different -//! ways to interface with the OS RNG so it's worth exploring each of the options. -//! Note that at the time of writing these all go through the (undocumented) -//! `bcryptPrimitives.dll` but they use different route to get there. -//! -//! Originally we were using [`RtlGenRandom`], however that function is -//! deprecated and warns it "may be altered or unavailable in subsequent versions". -//! -//! So we switched to [`BCryptGenRandom`] with the `BCRYPT_USE_SYSTEM_PREFERRED_RNG` -//! flag to query and find the system configured RNG. However, this change caused a small -//! but significant number of users to experience panics caused by a failure of -//! this function. See [#94098]. -//! -//! The current version falls back to using `BCryptOpenAlgorithmProvider` if -//! `BCRYPT_USE_SYSTEM_PREFERRED_RNG` fails for any reason. -//! -//! [#94098]: https://github.com/rust-lang/rust/issues/94098 -//! [`RtlGenRandom`]: https://docs.microsoft.com/en-us/windows/win32/api/ntsecapi/nf-ntsecapi-rtlgenrandom -//! [`BCryptGenRandom`]: https://docs.microsoft.com/en-us/windows/win32/api/bcrypt/nf-bcrypt-bcryptgenrandom +use crate::io; use crate::mem; use crate::ptr; use crate::sys::c; -/// Generates high quality secure random keys for use by [`HashMap`]. -/// -/// This is used to seed the default [`RandomState`]. -/// -/// [`HashMap`]: crate::collections::HashMap -/// [`RandomState`]: crate::collections::hash_map::RandomState pub fn hashmap_random_keys() -> (u64, u64) { - Rng::SYSTEM.gen_random_keys().unwrap_or_else(fallback_rng) + let mut v = (0, 0); + let ret = unsafe { + c::BCryptGenRandom( + ptr::null_mut(), + &mut v as *mut _ as *mut u8, + mem::size_of_val(&v) as c::ULONG, + c::BCRYPT_USE_SYSTEM_PREFERRED_RNG, + ) + }; + if c::nt_success(ret) { v } else { fallback_rng() } } -struct Rng { - algorithm: c::BCRYPT_ALG_HANDLE, - flags: u32, -} -impl Rng { - const SYSTEM: Self = unsafe { Self::new(ptr::null_mut(), c::BCRYPT_USE_SYSTEM_PREFERRED_RNG) }; - - /// Create the RNG from an existing algorithm handle. - /// - /// # Safety - /// - /// The handle must either be null or a valid algorithm handle. - const unsafe fn new(algorithm: c::BCRYPT_ALG_HANDLE, flags: u32) -> Self { - Self { algorithm, flags } - } - - /// Open a handle to the RNG algorithm. - fn open() -> Result { - use crate::sync::atomic::AtomicPtr; - use crate::sync::atomic::Ordering::{Acquire, Release}; - - // An atomic is used so we don't need to reopen the handle every time. - static HANDLE: AtomicPtr = AtomicPtr::new(ptr::null_mut()); - - let mut handle = HANDLE.load(Acquire); - if handle.is_null() { - let status = unsafe { - c::BCryptOpenAlgorithmProvider( - &mut handle, - c::BCRYPT_RNG_ALGORITHM.as_ptr(), - ptr::null(), - 0, - ) - }; - if c::nt_success(status) { - // If another thread opens a handle first then use that handle instead. - let result = HANDLE.compare_exchange(ptr::null_mut(), handle, Release, Acquire); - if let Err(previous_handle) = result { - // Close our handle and return the previous one. - unsafe { c::BCryptCloseAlgorithmProvider(handle, 0) }; - handle = previous_handle; - } - Ok(unsafe { Self::new(handle, 0) }) - } else { - Err(status) - } - } else { - Ok(unsafe { Self::new(handle, 0) }) - } - } +/// Generate random numbers using the fallback RNG function (RtlGenRandom) +/// +/// This is necessary because of a failure to load the SysWOW64 variant of the +/// bcryptprimitives.dll library from code that lives in bcrypt.dll +/// See +#[cfg(not(target_vendor = "uwp"))] +#[inline(never)] +fn fallback_rng() -> (u64, u64) { + let mut v = (0, 0); + let ret = + unsafe { c::RtlGenRandom(&mut v as *mut _ as *mut u8, mem::size_of_val(&v) as c::ULONG) }; - fn gen_random_keys(self) -> Result<(u64, u64), c::NTSTATUS> { - let mut v = (0, 0); - let status = unsafe { - let size = mem::size_of_val(&v).try_into().unwrap(); - c::BCryptGenRandom(self.algorithm, ptr::addr_of_mut!(v).cast(), size, self.flags) - }; - if c::nt_success(status) { Ok(v) } else { Err(status) } - } + if ret != 0 { v } else { panic!("fallback RNG broken: {}", io::Error::last_os_error()) } } -/// Generate random numbers using the fallback RNG function +/// We can't use RtlGenRandom with UWP, so there is no fallback +#[cfg(target_vendor = "uwp")] #[inline(never)] -fn fallback_rng(rng_status: c::NTSTATUS) -> (u64, u64) { - match Rng::open().and_then(|rng| rng.gen_random_keys()) { - Ok(keys) => keys, - Err(status) => { - panic!("RNG broken: {rng_status:#x}, fallback RNG broken: {status:#x}") - } - } +fn fallback_rng() -> (u64, u64) { + panic!("fallback RNG broken: RtlGenRandom() not supported on UWP"); } -- cgit v1.2.3