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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 19:33:14 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 19:33:14 +0000
commit36d22d82aa202bb199967e9512281e9a53db42c9 (patch)
tree105e8c98ddea1c1e4784a60a5a6410fa416be2de /third_party/rust/getrandom/src/lib.rs
parentInitial commit. (diff)
downloadfirefox-esr-upstream.tar.xz
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Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
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+// Copyright 2019 Developers of the Rand project.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+//! Interface to the operating system's random number generator.
+//!
+//! # Supported targets
+//!
+//! | Target | Target Triple | Implementation
+//! | ----------------- | ------------------ | --------------
+//! | Linux, Android | `*‑linux‑*` | [`getrandom`][1] system call if available, otherwise [`/dev/urandom`][2] after successfully polling `/dev/random`
+//! | Windows | `*‑windows‑*` | [`BCryptGenRandom`]
+//! | macOS | `*‑apple‑darwin` | [`getentropy`][3] if available, otherwise [`/dev/urandom`][4] (identical to `/dev/random`)
+//! | iOS, tvOS, watchOS | `*‑apple‑ios`, `*-apple-tvos`, `*-apple-watchos` | [`SecRandomCopyBytes`]
+//! | FreeBSD | `*‑freebsd` | [`getrandom`][5] if available, otherwise [`kern.arandom`][6]
+//! | OpenBSD | `*‑openbsd` | [`getentropy`][7]
+//! | NetBSD | `*‑netbsd` | [`getrandom`][16] if available, otherwise [`kern.arandom`][8]
+//! | Dragonfly BSD | `*‑dragonfly` | [`getrandom`][9] if available, otherwise [`/dev/urandom`][10] (identical to `/dev/random`)
+//! | Solaris, illumos | `*‑solaris`, `*‑illumos` | [`getrandom`][11] if available, otherwise [`/dev/random`][12]
+//! | Fuchsia OS | `*‑fuchsia` | [`cprng_draw`]
+//! | Redox | `*‑redox` | `/dev/urandom`
+//! | Haiku | `*‑haiku` | `/dev/urandom` (identical to `/dev/random`)
+//! | Hermit | `*-hermit` | [`sys_read_entropy`]
+//! | SGX | `x86_64‑*‑sgx` | [`RDRAND`]
+//! | VxWorks | `*‑wrs‑vxworks‑*` | `randABytes` after checking entropy pool initialization with `randSecure`
+//! | ESP-IDF | `*‑espidf` | [`esp_fill_random`]
+//! | Emscripten | `*‑emscripten` | [`getentropy`][13]
+//! | WASI | `wasm32‑wasi` | [`random_get`]
+//! | Web Browser and Node.js | `wasm*‑*‑unknown` | [`Crypto.getRandomValues`] if available, then [`crypto.randomFillSync`] if on Node.js, see [WebAssembly support]
+//! | SOLID | `*-kmc-solid_*` | `SOLID_RNG_SampleRandomBytes`
+//! | Nintendo 3DS | `armv6k-nintendo-3ds` | [`getrandom`][1]
+//! | QNX Neutrino | `*‑nto-qnx*` | [`/dev/urandom`][14] (identical to `/dev/random`)
+//! | AIX | `*-ibm-aix` | [`/dev/urandom`][15]
+//!
+//! There is no blanket implementation on `unix` targets that reads from
+//! `/dev/urandom`. This ensures all supported targets are using the recommended
+//! interface and respect maximum buffer sizes.
+//!
+//! Pull Requests that add support for new targets to `getrandom` are always welcome.
+//!
+//! ## Unsupported targets
+//!
+//! By default, `getrandom` will not compile on unsupported targets, but certain
+//! features allow a user to select a "fallback" implementation if no supported
+//! implementation exists.
+//!
+//! All of the below mechanisms only affect unsupported
+//! targets. Supported targets will _always_ use their supported implementations.
+//! This prevents a crate from overriding a secure source of randomness
+//! (either accidentally or intentionally).
+//!
+//! ### RDRAND on x86
+//!
+//! *If the `rdrand` Cargo feature is enabled*, `getrandom` will fallback to using
+//! the [`RDRAND`] instruction to get randomness on `no_std` `x86`/`x86_64`
+//! targets. This feature has no effect on other CPU architectures.
+//!
+//! ### WebAssembly support
+//!
+//! This crate fully supports the
+//! [`wasm32-wasi`](https://github.com/CraneStation/wasi) and
+//! [`wasm32-unknown-emscripten`](https://www.hellorust.com/setup/emscripten/)
+//! targets. However, the `wasm32-unknown-unknown` target (i.e. the target used
+//! by `wasm-pack`) is not automatically
+//! supported since, from the target name alone, we cannot deduce which
+//! JavaScript interface is in use (or if JavaScript is available at all).
+//!
+//! Instead, *if the `js` Cargo feature is enabled*, this crate will assume
+//! that you are building for an environment containing JavaScript, and will
+//! call the appropriate methods. Both web browser (main window and Web Workers)
+//! and Node.js environments are supported, invoking the methods
+//! [described above](#supported-targets) using the [`wasm-bindgen`] toolchain.
+//!
+//! To enable the `js` Cargo feature, add the following to the `dependencies`
+//! section in your `Cargo.toml` file:
+//! ```toml
+//! [dependencies]
+//! getrandom = { version = "0.2", features = ["js"] }
+//! ```
+//!
+//! This can be done even if `getrandom` is not a direct dependency. Cargo
+//! allows crates to enable features for indirect dependencies.
+//!
+//! This feature should only be enabled for binary, test, or benchmark crates.
+//! Library crates should generally not enable this feature, leaving such a
+//! decision to *users* of their library. Also, libraries should not introduce
+//! their own `js` features *just* to enable `getrandom`'s `js` feature.
+//!
+//! This feature has no effect on targets other than `wasm32-unknown-unknown`.
+//!
+//! #### Node.js ES module support
+//!
+//! Node.js supports both [CommonJS modules] and [ES modules]. Due to
+//! limitations in wasm-bindgen's [`module`] support, we cannot directly
+//! support ES Modules running on Node.js. However, on Node v15 and later, the
+//! module author can add a simple shim to support the Web Cryptography API:
+//! ```js
+//! import { webcrypto } from 'node:crypto'
+//! globalThis.crypto = webcrypto
+//! ```
+//! This crate will then use the provided `webcrypto` implementation.
+//!
+//! ### Custom implementations
+//!
+//! The [`register_custom_getrandom!`] macro allows a user to mark their own
+//! function as the backing implementation for [`getrandom`]. See the macro's
+//! documentation for more information about writing and registering your own
+//! custom implementations.
+//!
+//! Note that registering a custom implementation only has an effect on targets
+//! that would otherwise not compile. Any supported targets (including those
+//! using `rdrand` and `js` Cargo features) continue using their normal
+//! implementations even if a function is registered.
+//!
+//! ## Early boot
+//!
+//! Sometimes, early in the boot process, the OS has not collected enough
+//! entropy to securely seed its RNG. This is especially common on virtual
+//! machines, where standard "random" events are hard to come by.
+//!
+//! Some operating system interfaces always block until the RNG is securely
+//! seeded. This can take anywhere from a few seconds to more than a minute.
+//! A few (Linux, NetBSD and Solaris) offer a choice between blocking and
+//! getting an error; in these cases, we always choose to block.
+//!
+//! On Linux (when the `getrandom` system call is not available), reading from
+//! `/dev/urandom` never blocks, even when the OS hasn't collected enough
+//! entropy yet. To avoid returning low-entropy bytes, we first poll
+//! `/dev/random` and only switch to `/dev/urandom` once this has succeeded.
+//!
+//! On OpenBSD, this kind of entropy accounting isn't available, and on
+//! NetBSD, blocking on it is discouraged. On these platforms, nonblocking
+//! interfaces are used, even when reliable entropy may not be available.
+//! On the platforms where it is used, the reliability of entropy accounting
+//! itself isn't free from controversy. This library provides randomness
+//! sourced according to the platform's best practices, but each platform has
+//! its own limits on the grade of randomness it can promise in environments
+//! with few sources of entropy.
+//!
+//! ## Error handling
+//!
+//! We always choose failure over returning known insecure "random" bytes. In
+//! general, on supported platforms, failure is highly unlikely, though not
+//! impossible. If an error does occur, then it is likely that it will occur
+//! on every call to `getrandom`, hence after the first successful call one
+//! can be reasonably confident that no errors will occur.
+//!
+//! [1]: http://man7.org/linux/man-pages/man2/getrandom.2.html
+//! [2]: http://man7.org/linux/man-pages/man4/urandom.4.html
+//! [3]: https://www.unix.com/man-page/mojave/2/getentropy/
+//! [4]: https://www.unix.com/man-page/mojave/4/urandom/
+//! [5]: https://www.freebsd.org/cgi/man.cgi?query=getrandom&manpath=FreeBSD+12.0-stable
+//! [6]: https://www.freebsd.org/cgi/man.cgi?query=random&sektion=4
+//! [7]: https://man.openbsd.org/getentropy.2
+//! [8]: https://man.netbsd.org/sysctl.7
+//! [9]: https://leaf.dragonflybsd.org/cgi/web-man?command=getrandom
+//! [10]: https://leaf.dragonflybsd.org/cgi/web-man?command=random&section=4
+//! [11]: https://docs.oracle.com/cd/E88353_01/html/E37841/getrandom-2.html
+//! [12]: https://docs.oracle.com/cd/E86824_01/html/E54777/random-7d.html
+//! [13]: https://github.com/emscripten-core/emscripten/pull/12240
+//! [14]: https://www.qnx.com/developers/docs/7.1/index.html#com.qnx.doc.neutrino.utilities/topic/r/random.html
+//! [15]: https://www.ibm.com/docs/en/aix/7.3?topic=files-random-urandom-devices
+//! [16]: https://man.netbsd.org/getrandom.2
+//!
+//! [`BCryptGenRandom`]: https://docs.microsoft.com/en-us/windows/win32/api/bcrypt/nf-bcrypt-bcryptgenrandom
+//! [`Crypto.getRandomValues`]: https://www.w3.org/TR/WebCryptoAPI/#Crypto-method-getRandomValues
+//! [`RDRAND`]: https://software.intel.com/en-us/articles/intel-digital-random-number-generator-drng-software-implementation-guide
+//! [`SecRandomCopyBytes`]: https://developer.apple.com/documentation/security/1399291-secrandomcopybytes?language=objc
+//! [`cprng_draw`]: https://fuchsia.dev/fuchsia-src/zircon/syscalls/cprng_draw
+//! [`crypto.randomFillSync`]: https://nodejs.org/api/crypto.html#cryptorandomfillsyncbuffer-offset-size
+//! [`esp_fill_random`]: https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/system/random.html#_CPPv415esp_fill_randomPv6size_t
+//! [`random_get`]: https://github.com/WebAssembly/WASI/blob/main/phases/snapshot/docs.md#-random_getbuf-pointeru8-buf_len-size---errno
+//! [WebAssembly support]: #webassembly-support
+//! [`wasm-bindgen`]: https://github.com/rustwasm/wasm-bindgen
+//! [`module`]: https://rustwasm.github.io/wasm-bindgen/reference/attributes/on-js-imports/module.html
+//! [CommonJS modules]: https://nodejs.org/api/modules.html
+//! [ES modules]: https://nodejs.org/api/esm.html
+//! [`sys_read_entropy`]: https://hermitcore.github.io/libhermit-rs/hermit/fn.sys_read_entropy.html
+
+#![doc(
+ html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk.png",
+ html_favicon_url = "https://www.rust-lang.org/favicon.ico",
+ html_root_url = "https://docs.rs/getrandom/0.2.9"
+)]
+#![no_std]
+#![warn(rust_2018_idioms, unused_lifetimes, missing_docs)]
+#![cfg_attr(docsrs, feature(doc_cfg))]
+
+#[macro_use]
+extern crate cfg_if;
+
+use crate::util::{slice_as_uninit_mut, slice_assume_init_mut};
+use core::mem::MaybeUninit;
+
+mod error;
+mod util;
+// To prevent a breaking change when targets are added, we always export the
+// register_custom_getrandom macro, so old Custom RNG crates continue to build.
+#[cfg(feature = "custom")]
+mod custom;
+#[cfg(feature = "std")]
+mod error_impls;
+
+pub use crate::error::Error;
+
+// System-specific implementations.
+//
+// These should all provide getrandom_inner with the signature
+// `fn getrandom_inner(dest: &mut [MaybeUninit<u8>]) -> Result<(), Error>`.
+// The function MUST fully initialize `dest` when `Ok(())` is returned.
+// The function MUST NOT ever write uninitialized bytes into `dest`,
+// regardless of what value it returns.
+cfg_if! {
+ if #[cfg(any(target_os = "haiku", target_os = "redox", target_os = "nto", target_os = "aix"))] {
+ mod util_libc;
+ #[path = "use_file.rs"] mod imp;
+ } else if #[cfg(any(target_os = "android", target_os = "linux"))] {
+ mod util_libc;
+ mod use_file;
+ #[path = "linux_android.rs"] mod imp;
+ } else if #[cfg(any(target_os = "illumos", target_os = "solaris"))] {
+ mod util_libc;
+ mod use_file;
+ #[path = "solaris_illumos.rs"] mod imp;
+ } else if #[cfg(any(target_os = "freebsd", target_os = "netbsd"))] {
+ mod util_libc;
+ #[path = "bsd_arandom.rs"] mod imp;
+ } else if #[cfg(target_os = "dragonfly")] {
+ mod util_libc;
+ mod use_file;
+ #[path = "dragonfly.rs"] mod imp;
+ } else if #[cfg(target_os = "fuchsia")] {
+ #[path = "fuchsia.rs"] mod imp;
+ } else if #[cfg(any(target_os = "ios", target_os = "watchos", target_os = "tvos"))] {
+ #[path = "apple-other.rs"] mod imp;
+ } else if #[cfg(target_os = "macos")] {
+ mod util_libc;
+ mod use_file;
+ #[path = "macos.rs"] mod imp;
+ } else if #[cfg(target_os = "openbsd")] {
+ mod util_libc;
+ #[path = "openbsd.rs"] mod imp;
+ } else if #[cfg(all(target_arch = "wasm32", target_os = "wasi"))] {
+ #[path = "wasi.rs"] mod imp;
+ } else if #[cfg(target_os = "hermit")] {
+ #[path = "hermit.rs"] mod imp;
+ } else if #[cfg(target_os = "vxworks")] {
+ mod util_libc;
+ #[path = "vxworks.rs"] mod imp;
+ } else if #[cfg(target_os = "solid_asp3")] {
+ #[path = "solid.rs"] mod imp;
+ } else if #[cfg(target_os = "espidf")] {
+ #[path = "espidf.rs"] mod imp;
+ } else if #[cfg(windows)] {
+ #[path = "windows.rs"] mod imp;
+ } else if #[cfg(all(target_os = "horizon", target_arch = "arm"))] {
+ // We check for target_arch = "arm" because the Nintendo Switch also
+ // uses Horizon OS (it is aarch64).
+ mod util_libc;
+ #[path = "3ds.rs"] mod imp;
+ } else if #[cfg(target_os = "emscripten")] {
+ mod util_libc;
+ #[path = "emscripten.rs"] mod imp;
+ } else if #[cfg(all(target_arch = "x86_64", target_env = "sgx"))] {
+ #[path = "rdrand.rs"] mod imp;
+ } else if #[cfg(all(feature = "rdrand",
+ any(target_arch = "x86_64", target_arch = "x86")))] {
+ #[path = "rdrand.rs"] mod imp;
+ } else if #[cfg(all(feature = "js",
+ any(target_arch = "wasm32", target_arch = "wasm64"),
+ target_os = "unknown"))] {
+ #[path = "js.rs"] mod imp;
+ } else if #[cfg(feature = "custom")] {
+ use custom as imp;
+ } else if #[cfg(all(any(target_arch = "wasm32", target_arch = "wasm64"),
+ target_os = "unknown"))] {
+ compile_error!("the wasm*-unknown-unknown targets are not supported by \
+ default, you may need to enable the \"js\" feature. \
+ For more information see: \
+ https://docs.rs/getrandom/#webassembly-support");
+ } else {
+ compile_error!("target is not supported, for more information see: \
+ https://docs.rs/getrandom/#unsupported-targets");
+ }
+}
+
+/// Fill `dest` with random bytes from the system's preferred random number
+/// source.
+///
+/// This function returns an error on any failure, including partial reads. We
+/// make no guarantees regarding the contents of `dest` on error. If `dest` is
+/// empty, `getrandom` immediately returns success, making no calls to the
+/// underlying operating system.
+///
+/// Blocking is possible, at least during early boot; see module documentation.
+///
+/// In general, `getrandom` will be fast enough for interactive usage, though
+/// significantly slower than a user-space CSPRNG; for the latter consider
+/// [`rand::thread_rng`](https://docs.rs/rand/*/rand/fn.thread_rng.html).
+#[inline]
+pub fn getrandom(dest: &mut [u8]) -> Result<(), Error> {
+ // SAFETY: The `&mut MaybeUninit<_>` reference doesn't escape, and
+ // `getrandom_uninit` guarantees it will never de-initialize any part of
+ // `dest`.
+ getrandom_uninit(unsafe { slice_as_uninit_mut(dest) })?;
+ Ok(())
+}
+
+/// Version of the `getrandom` function which fills `dest` with random bytes
+/// returns a mutable reference to those bytes.
+///
+/// On successful completion this function is guaranteed to return a slice
+/// which points to the same memory as `dest` and has the same length.
+/// In other words, it's safe to assume that `dest` is initialized after
+/// this function has returned `Ok`.
+///
+/// No part of `dest` will ever be de-initialized at any point, regardless
+/// of what is returned.
+///
+/// # Examples
+///
+/// ```ignore
+/// # // We ignore this test since `uninit_array` is unstable.
+/// #![feature(maybe_uninit_uninit_array)]
+/// # fn main() -> Result<(), getrandom::Error> {
+/// let mut buf = core::mem::MaybeUninit::uninit_array::<1024>();
+/// let buf: &mut [u8] = getrandom::getrandom_uninit(&mut buf)?;
+/// # Ok(()) }
+/// ```
+#[inline]
+pub fn getrandom_uninit(dest: &mut [MaybeUninit<u8>]) -> Result<&mut [u8], Error> {
+ if !dest.is_empty() {
+ imp::getrandom_inner(dest)?;
+ }
+ // SAFETY: `dest` has been fully initialized by `imp::getrandom_inner`
+ // since it returned `Ok`.
+ Ok(unsafe { slice_assume_init_mut(dest) })
+}