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Diffstat (limited to 'rand/src/rngs/os.rs')
| -rw-r--r-- | rand/src/rngs/os.rs | 1275 |
1 files changed, 1275 insertions, 0 deletions
diff --git a/rand/src/rngs/os.rs b/rand/src/rngs/os.rs new file mode 100644 index 0000000..e609c50 --- /dev/null +++ b/rand/src/rngs/os.rs @@ -0,0 +1,1275 @@ +// Copyright 2018 Developers of the Rand project. +// Copyright 2013-2015 The Rust Project Developers. +// +// 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 random number generator of the operating system. + +use std::fmt; +use rand_core::{CryptoRng, RngCore, Error, impls}; + +/// A random number generator that retrieves randomness straight from the +/// operating system. +/// +/// This is the preferred external source of entropy for most applications. +/// Commonly it is used to initialize a user-space RNG, which can then be used +/// to generate random values with much less overhead than `OsRng`. +/// +/// You may prefer to use [`EntropyRng`] instead of `OsRng`. It is unlikely, but +/// not entirely theoretical, for `OsRng` to fail. In such cases [`EntropyRng`] +/// falls back on a good alternative entropy source. +/// +/// `OsRng::new()` is guaranteed to be very cheap (after the first successful +/// call), and will never consume more than one file handle per process. +/// +/// # Platform sources +/// +/// | OS | interface +/// |------------------|--------------------------------------------------------- +/// | Linux, Android | [`getrandom`][1] system call if available, otherwise [`/dev/urandom`][2] after reading from `/dev/random` once +/// | Windows | [`RtlGenRandom`][3] +/// | macOS, iOS | [`SecRandomCopyBytes`][4] +/// | FreeBSD | [`kern.arandom`][5] +/// | OpenBSD, Bitrig | [`getentropy`][6] +/// | NetBSD | [`/dev/urandom`][7] after reading from `/dev/random` once +/// | Dragonfly BSD | [`/dev/random`][8] +/// | Solaris, illumos | [`getrandom`][9] system call if available, otherwise [`/dev/random`][10] +/// | Fuchsia OS | [`cprng_draw`][11] +/// | Redox | [`rand:`][12] +/// | CloudABI | [`random_get`][13] +/// | Haiku | `/dev/random` (identical to `/dev/urandom`) +/// | Web browsers | [`Crypto.getRandomValues`][14] (see [Support for WebAssembly and ams.js][14]) +/// | Node.js | [`crypto.randomBytes`][15] (see [Support for WebAssembly and ams.js][16]) +/// +/// Rand doesn't have a blanket implementation for all Unix-like operating +/// systems that reads from `/dev/urandom`. This ensures all supported operating +/// systems are using the recommended interface and respect maximum buffer +/// sizes. +/// +/// ## Support for WebAssembly and ams.js +/// +/// The three Emscripten targets `asmjs-unknown-emscripten`, +/// `wasm32-unknown-emscripten` and `wasm32-experimental-emscripten` use +/// Emscripten's emulation of `/dev/random` on web browsers and Node.js. +/// +/// The bare Wasm target `wasm32-unknown-unknown` tries to call the javascript +/// methods directly, using either `stdweb` in combination with `cargo-web` or +/// `wasm-bindgen` depending on what features are activated for this crate. +/// +/// ## Early boot +/// +/// It is possible that early in the boot process the OS hasn't had enough time +/// yet to collect entropy to securely seed its RNG, especially on virtual +/// machines. +/// +/// Some operating systems always block the thread until the RNG is securely +/// seeded. This can take anywhere from a few seconds to more than a minute. +/// Others make a best effort to use a seed from before the shutdown and don't +/// document much. +/// +/// A few, Linux, NetBSD and Solaris, offer a choice between blocking, and +/// getting an error. With `try_fill_bytes` we choose to get the error +/// ([`ErrorKind::NotReady`]), while the other methods use a blocking interface. +/// +/// On Linux (when the `genrandom` system call is not available) and on NetBSD +/// reading from `/dev/urandom` never blocks, even when the OS hasn't collected +/// enough entropy yet. As a countermeasure we try to do a single read from +/// `/dev/random` until we know the OS RNG is initialized (and store this in a +/// global static). +/// +/// # Panics +/// +/// `OsRng` is extremely unlikely to fail if `OsRng::new()`, and one read from +/// it, where succesfull. But in case it does fail, only [`try_fill_bytes`] is +/// able to report the cause. Depending on the error the other [`RngCore`] +/// methods will retry several times, and panic in case the error remains. +/// +/// [`EntropyRng`]: struct.EntropyRng.html +/// [`RngCore`]: ../trait.RngCore.html +/// [`try_fill_bytes`]: ../trait.RngCore.html#method.tymethod.try_fill_bytes +/// [`ErrorKind::NotReady`]: ../enum.ErrorKind.html#variant.NotReady +/// +/// [1]: http://man7.org/linux/man-pages/man2/getrandom.2.html +/// [2]: http://man7.org/linux/man-pages/man4/urandom.4.html +/// [3]: https://msdn.microsoft.com/en-us/library/windows/desktop/aa387694.aspx +/// [4]: https://developer.apple.com/documentation/security/1399291-secrandomcopybytes?language=objc +/// [5]: https://www.freebsd.org/cgi/man.cgi?query=random&sektion=4 +/// [6]: https://man.openbsd.org/getentropy.2 +/// [7]: http://netbsd.gw.com/cgi-bin/man-cgi?random+4+NetBSD-current +/// [8]: https://leaf.dragonflybsd.org/cgi/web-man?command=random§ion=4 +/// [9]: https://docs.oracle.com/cd/E88353_01/html/E37841/getrandom-2.html +/// [10]: https://docs.oracle.com/cd/E86824_01/html/E54777/random-7d.html +/// [11]: https://fuchsia.googlesource.com/zircon/+/HEAD/docs/syscalls/cprng_draw.md +/// [12]: https://github.com/redox-os/randd/blob/master/src/main.rs +/// [13]: https://github.com/NuxiNL/cloudabi/blob/v0.20/cloudabi.txt#L1826 +/// [14]: https://www.w3.org/TR/WebCryptoAPI/#Crypto-method-getRandomValues +/// [15]: https://nodejs.org/api/crypto.html#crypto_crypto_randombytes_size_callback +/// [16]: #support-for-webassembly-and-amsjs + + +#[derive(Clone)] +pub struct OsRng(imp::OsRng); + +impl fmt::Debug for OsRng { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + self.0.fmt(f) + } +} + +impl OsRng { + /// Create a new `OsRng`. + pub fn new() -> Result<OsRng, Error> { + imp::OsRng::new().map(OsRng) + } +} + +impl CryptoRng for OsRng {} + +impl RngCore for OsRng { + fn next_u32(&mut self) -> u32 { + impls::next_u32_via_fill(self) + } + + fn next_u64(&mut self) -> u64 { + impls::next_u64_via_fill(self) + } + + fn fill_bytes(&mut self, dest: &mut [u8]) { + use std::{time, thread}; + + // We cannot return Err(..), so we try to handle before panicking. + const MAX_RETRY_PERIOD: u32 = 10; // max 10s + const WAIT_DUR_MS: u32 = 100; // retry every 100ms + let wait_dur = time::Duration::from_millis(WAIT_DUR_MS as u64); + const RETRY_LIMIT: u32 = (MAX_RETRY_PERIOD * 1000) / WAIT_DUR_MS; + const TRANSIENT_RETRIES: u32 = 8; + let mut err_count = 0; + let mut error_logged = false; + + // Maybe block until the OS RNG is initialized + let mut read = 0; + if let Ok(n) = self.0.test_initialized(dest, true) { read = n }; + let dest = &mut dest[read..]; + + loop { + if let Err(e) = self.try_fill_bytes(dest) { + if err_count >= RETRY_LIMIT { + error!("OsRng failed too many times; last error: {}", e); + panic!("OsRng failed too many times; last error: {}", e); + } + + if e.kind.should_wait() { + if !error_logged { + warn!("OsRng failed; waiting up to {}s and retrying. Error: {}", + MAX_RETRY_PERIOD, e); + error_logged = true; + } + err_count += 1; + thread::sleep(wait_dur); + continue; + } else if e.kind.should_retry() { + if !error_logged { + warn!("OsRng failed; retrying up to {} times. Error: {}", + TRANSIENT_RETRIES, e); + error_logged = true; + } + err_count += (RETRY_LIMIT + TRANSIENT_RETRIES - 1) + / TRANSIENT_RETRIES; // round up + continue; + } else { + error!("OsRng failed: {}", e); + panic!("OsRng fatal error: {}", e); + } + } + + break; + } + } + + fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), Error> { + // Some systems do not support reading 0 random bytes. + // (And why waste a system call?) + if dest.len() == 0 { return Ok(()); } + + let read = self.0.test_initialized(dest, false)?; + let dest = &mut dest[read..]; + + let max = self.0.max_chunk_size(); + if dest.len() <= max { + trace!("OsRng: reading {} bytes via {}", + dest.len(), self.0.method_str()); + } else { + trace!("OsRng: reading {} bytes via {} in {} chunks of {} bytes", + dest.len(), self.0.method_str(), (dest.len() + max) / max, max); + } + for slice in dest.chunks_mut(max) { + self.0.fill_chunk(slice)?; + } + Ok(()) + } +} + +trait OsRngImpl where Self: Sized { + // Create a new `OsRng` platform interface. + fn new() -> Result<Self, Error>; + + // Fill a chunk with random bytes. + fn fill_chunk(&mut self, dest: &mut [u8]) -> Result<(), Error>; + + // Test whether the OS RNG is initialized. This method may not be possible + // to support cheaply (or at all) on all operating systems. + // + // If `blocking` is set, this will cause the OS the block execution until + // its RNG is initialized. + // + // Random values that are read while this are stored in `dest`, the amount + // of read bytes is returned. + fn test_initialized(&mut self, _dest: &mut [u8], _blocking: bool) + -> Result<usize, Error> { Ok(0) } + + // Maximum chunk size supported. + fn max_chunk_size(&self) -> usize { ::core::usize::MAX } + + // Name of the OS interface (used for logging). + fn method_str(&self) -> &'static str; +} + + + + +// Helper functions to read from a random device such as `/dev/urandom`. +// +// All instances use a single internal file handle, to prevent possible +// exhaustion of file descriptors. +#[cfg(any(target_os = "linux", target_os = "android", + target_os = "netbsd", target_os = "dragonfly", + target_os = "solaris", target_os = "redox", + target_os = "haiku", target_os = "emscripten"))] +mod random_device { + use {Error, ErrorKind}; + use std::fs::File; + use std::io; + use std::io::Read; + use std::sync::{Once, Mutex, ONCE_INIT}; + + // TODO: remove outer Option when `Mutex::new(None)` is a constant expression + static mut READ_RNG_FILE: Option<Mutex<Option<File>>> = None; + static READ_RNG_ONCE: Once = ONCE_INIT; + + #[allow(unused)] + pub fn open<F>(path: &'static str, open_fn: F) -> Result<(), Error> + where F: Fn(&'static str) -> Result<File, io::Error> + { + READ_RNG_ONCE.call_once(|| { + unsafe { READ_RNG_FILE = Some(Mutex::new(None)) } + }); + + // We try opening the file outside the `call_once` fn because we cannot + // clone the error, thus we must retry on failure. + + let mutex = unsafe { READ_RNG_FILE.as_ref().unwrap() }; + let mut guard = mutex.lock().unwrap(); + if (*guard).is_none() { + info!("OsRng: opening random device {}", path); + let file = open_fn(path).map_err(map_err)?; + *guard = Some(file); + }; + Ok(()) + } + + pub fn read(dest: &mut [u8]) -> Result<(), Error> { + // We expect this function only to be used after `random_device::open` + // was succesful. Therefore we can assume that our memory was set with a + // valid object. + let mutex = unsafe { READ_RNG_FILE.as_ref().unwrap() }; + let mut guard = mutex.lock().unwrap(); + let file = (*guard).as_mut().unwrap(); + + // Use `std::io::read_exact`, which retries on `ErrorKind::Interrupted`. + file.read_exact(dest).map_err(|err| { + Error::with_cause(ErrorKind::Unavailable, + "error reading random device", err) + }) + + } + + pub fn map_err(err: io::Error) -> Error { + match err.kind() { + io::ErrorKind::Interrupted => + Error::new(ErrorKind::Transient, "interrupted"), + io::ErrorKind::WouldBlock => + Error::with_cause(ErrorKind::NotReady, + "OS RNG not yet seeded", err), + _ => Error::with_cause(ErrorKind::Unavailable, + "error while opening random device", err) + } + } +} + + +#[cfg(any(target_os = "linux", target_os = "android"))] +mod imp { + extern crate libc; + + use {Error, ErrorKind}; + use super::random_device; + use super::OsRngImpl; + + use std::io; + use std::io::Read; + use std::fs::{File, OpenOptions}; + use std::os::unix::fs::OpenOptionsExt; + use std::sync::atomic::{AtomicBool, ATOMIC_BOOL_INIT, Ordering}; + use std::sync::{Once, ONCE_INIT}; + + #[derive(Clone, Debug)] + pub struct OsRng { + method: OsRngMethod, + initialized: bool, + } + + #[derive(Clone, Debug)] + enum OsRngMethod { + GetRandom, + RandomDevice, + } + + impl OsRngImpl for OsRng { + fn new() -> Result<OsRng, Error> { + if is_getrandom_available() { + return Ok(OsRng { method: OsRngMethod::GetRandom, + initialized: false }); + } + random_device::open("/dev/urandom", &|p| File::open(p))?; + Ok(OsRng { method: OsRngMethod::RandomDevice, initialized: false }) + } + + fn fill_chunk(&mut self, dest: &mut [u8]) -> Result<(), Error> { + match self.method { + OsRngMethod::GetRandom => getrandom_try_fill(dest, false), + OsRngMethod::RandomDevice => random_device::read(dest), + } + } + + fn test_initialized(&mut self, dest: &mut [u8], blocking: bool) + -> Result<usize, Error> + { + static OS_RNG_INITIALIZED: AtomicBool = ATOMIC_BOOL_INIT; + if !self.initialized { + self.initialized = OS_RNG_INITIALIZED.load(Ordering::Relaxed); + } + if self.initialized { return Ok(0); } + + let result = match self.method { + OsRngMethod::GetRandom => { + getrandom_try_fill(dest, blocking)?; + Ok(dest.len()) + } + OsRngMethod::RandomDevice => { + info!("OsRng: testing random device /dev/random"); + let mut file = OpenOptions::new() + .read(true) + .custom_flags(if blocking { 0 } else { libc::O_NONBLOCK }) + .open("/dev/random") + .map_err(random_device::map_err)?; + file.read(&mut dest[..1]).map_err(random_device::map_err)?; + Ok(1) + } + }; + OS_RNG_INITIALIZED.store(true, Ordering::Relaxed); + self.initialized = true; + result + } + + fn method_str(&self) -> &'static str { + match self.method { + OsRngMethod::GetRandom => "getrandom", + OsRngMethod::RandomDevice => "/dev/urandom", + } + } + } + + #[cfg(target_arch = "x86_64")] + const NR_GETRANDOM: libc::c_long = 318; + #[cfg(target_arch = "x86")] + const NR_GETRANDOM: libc::c_long = 355; + #[cfg(target_arch = "arm")] + const NR_GETRANDOM: libc::c_long = 384; + #[cfg(target_arch = "aarch64")] + const NR_GETRANDOM: libc::c_long = 278; + #[cfg(target_arch = "s390x")] + const NR_GETRANDOM: libc::c_long = 349; + #[cfg(target_arch = "powerpc")] + const NR_GETRANDOM: libc::c_long = 359; + #[cfg(target_arch = "powerpc64")] + const NR_GETRANDOM: libc::c_long = 359; + #[cfg(target_arch = "mips")] // old ABI + const NR_GETRANDOM: libc::c_long = 4353; + #[cfg(target_arch = "mips64")] + const NR_GETRANDOM: libc::c_long = 5313; + #[cfg(target_arch = "sparc")] + const NR_GETRANDOM: libc::c_long = 347; + #[cfg(target_arch = "sparc64")] + const NR_GETRANDOM: libc::c_long = 347; + #[cfg(not(any(target_arch = "x86_64", target_arch = "x86", + target_arch = "arm", target_arch = "aarch64", + target_arch = "s390x", target_arch = "powerpc", + target_arch = "powerpc64", target_arch = "mips", + target_arch = "mips64", target_arch = "sparc", + target_arch = "sparc64")))] + const NR_GETRANDOM: libc::c_long = 0; + + fn getrandom(buf: &mut [u8], blocking: bool) -> libc::c_long { + const GRND_NONBLOCK: libc::c_uint = 0x0001; + + if NR_GETRANDOM == 0 { return -1 }; + + unsafe { + libc::syscall(NR_GETRANDOM, buf.as_mut_ptr(), buf.len(), + if blocking { 0 } else { GRND_NONBLOCK }) + } + } + + fn getrandom_try_fill(dest: &mut [u8], blocking: bool) -> Result<(), Error> { + let mut read = 0; + while read < dest.len() { + let result = getrandom(&mut dest[read..], blocking); + if result == -1 { + let err = io::Error::last_os_error(); + let kind = err.kind(); + if kind == io::ErrorKind::Interrupted { + continue; + } else if kind == io::ErrorKind::WouldBlock { + return Err(Error::with_cause( + ErrorKind::NotReady, + "getrandom not ready", + err, + )); + } else { + return Err(Error::with_cause( + ErrorKind::Unavailable, + "unexpected getrandom error", + err, + )); + } + } else { + read += result as usize; + } + } + Ok(()) + } + + fn is_getrandom_available() -> bool { + static CHECKER: Once = ONCE_INIT; + static AVAILABLE: AtomicBool = ATOMIC_BOOL_INIT; + + if NR_GETRANDOM == 0 { return false }; + + CHECKER.call_once(|| { + debug!("OsRng: testing getrandom"); + let mut buf: [u8; 0] = []; + let result = getrandom(&mut buf, false); + let available = if result == -1 { + let err = io::Error::last_os_error().raw_os_error(); + err != Some(libc::ENOSYS) + } else { + true + }; + AVAILABLE.store(available, Ordering::Relaxed); + info!("OsRng: using {}", if available { "getrandom" } else { "/dev/urandom" }); + }); + + AVAILABLE.load(Ordering::Relaxed) + } +} + + +#[cfg(target_os = "netbsd")] +mod imp { + use Error; + use super::random_device; + use super::OsRngImpl; + + use std::fs::File; + use std::io::Read; + use std::sync::atomic::{AtomicBool, ATOMIC_BOOL_INIT, Ordering}; + + #[derive(Clone, Debug)] + pub struct OsRng { initialized: bool } + + impl OsRngImpl for OsRng { + fn new() -> Result<OsRng, Error> { + random_device::open("/dev/urandom", &|p| File::open(p))?; + Ok(OsRng { initialized: false }) + } + + fn fill_chunk(&mut self, dest: &mut [u8]) -> Result<(), Error> { + random_device::read(dest) + } + + // Read a single byte from `/dev/random` to determine if the OS RNG is + // already seeded. NetBSD always blocks if not yet ready. + fn test_initialized(&mut self, dest: &mut [u8], _blocking: bool) + -> Result<usize, Error> + { + static OS_RNG_INITIALIZED: AtomicBool = ATOMIC_BOOL_INIT; + if !self.initialized { + self.initialized = OS_RNG_INITIALIZED.load(Ordering::Relaxed); + } + if self.initialized { return Ok(0); } + + info!("OsRng: testing random device /dev/random"); + let mut file = + File::open("/dev/random").map_err(random_device::map_err)?; + file.read(&mut dest[..1]).map_err(random_device::map_err)?; + + OS_RNG_INITIALIZED.store(true, Ordering::Relaxed); + self.initialized = true; + Ok(1) + } + + fn method_str(&self) -> &'static str { "/dev/urandom" } + } +} + + +#[cfg(any(target_os = "dragonfly", + target_os = "haiku", + target_os = "emscripten"))] +mod imp { + use Error; + use super::random_device; + use super::OsRngImpl; + use std::fs::File; + + #[derive(Clone, Debug)] + pub struct OsRng(); + + impl OsRngImpl for OsRng { + fn new() -> Result<OsRng, Error> { + random_device::open("/dev/random", &|p| File::open(p))?; + Ok(OsRng()) + } + + fn fill_chunk(&mut self, dest: &mut [u8]) -> Result<(), Error> { + random_device::read(dest) + } + + #[cfg(target_os = "emscripten")] + fn max_chunk_size(&self) -> usize { + // `Crypto.getRandomValues` documents `dest` should be at most 65536 + // bytes. `crypto.randomBytes` documents: "To minimize threadpool + // task length variation, partition large randomBytes requests when + // doing so as part of fulfilling a client request. + 65536 + } + + fn method_str(&self) -> &'static str { "/dev/random" } + } +} + + +// Read from `/dev/random`, with chunks of limited size (1040 bytes). +// `/dev/random` uses the Hash_DRBG with SHA512 algorithm from NIST SP 800-90A. +// `/dev/urandom` uses the FIPS 186-2 algorithm, which is considered less +// secure. We choose to read from `/dev/random`. +// +// Since Solaris 11.3 the `getrandom` syscall is available. To make sure we can +// compile on both Solaris and on OpenSolaris derivatives, that do not have the +// function, we do a direct syscall instead of calling a library function. +// +// We have no way to differentiate between Solaris, illumos, SmartOS, etc. +#[cfg(target_os = "solaris")] +mod imp { + extern crate libc; + + use {Error, ErrorKind}; + use super::random_device; + use super::OsRngImpl; + + use std::io; + use std::io::Read; + use std::fs::{File, OpenOptions}; + use std::os::unix::fs::OpenOptionsExt; + use std::sync::atomic::{AtomicBool, ATOMIC_BOOL_INIT, Ordering}; + + #[derive(Clone, Debug)] + pub struct OsRng { + method: OsRngMethod, + initialized: bool, + } + + #[derive(Clone, Debug)] + enum OsRngMethod { + GetRandom, + RandomDevice, + } + + impl OsRngImpl for OsRng { + fn new() -> Result<OsRng, Error> { + if is_getrandom_available() { + return Ok(OsRng { method: OsRngMethod::GetRandom, + initialized: false }); + } + let open = |p| OpenOptions::new() + .read(true) + .custom_flags(libc::O_NONBLOCK) + .open(p); + random_device::open("/dev/random", &open)?; + Ok(OsRng { method: OsRngMethod::RandomDevice, initialized: false }) + } + + fn fill_chunk(&mut self, dest: &mut [u8]) -> Result<(), Error> { + match self.method { + OsRngMethod::GetRandom => getrandom_try_fill(dest, false), + OsRngMethod::RandomDevice => random_device::read(dest), + } + } + + fn test_initialized(&mut self, dest: &mut [u8], blocking: bool) + -> Result<usize, Error> + { + static OS_RNG_INITIALIZED: AtomicBool = ATOMIC_BOOL_INIT; + if !self.initialized { + self.initialized = OS_RNG_INITIALIZED.load(Ordering::Relaxed); + } + if self.initialized { return Ok(0); } + + let chunk_len = ::core::cmp::min(1024, dest.len()); + let dest = &mut dest[..chunk_len]; + + match self.method { + OsRngMethod::GetRandom => getrandom_try_fill(dest, blocking)?, + OsRngMethod::RandomDevice => { + if blocking { + info!("OsRng: testing random device /dev/random"); + // We already have a non-blocking handle, but now need a + // blocking one. Not much choice except opening it twice + let mut file = File::open("/dev/random") + .map_err(random_device::map_err)?; + file.read(dest).map_err(random_device::map_err)?; + } else { + self.fill_chunk(dest)?; + } + } + }; + OS_RNG_INITIALIZED.store(true, Ordering::Relaxed); + self.initialized = true; + Ok(chunk_len) + } + + fn max_chunk_size(&self) -> usize { + // The documentation says 1024 is the maximum for getrandom, but + // 1040 for /dev/random. + 1024 + } + + fn method_str(&self) -> &'static str { + match self.method { + OsRngMethod::GetRandom => "getrandom", + OsRngMethod::RandomDevice => "/dev/random", + } + } + } + + fn getrandom(buf: &mut [u8], blocking: bool) -> libc::c_long { + extern "C" { + fn syscall(number: libc::c_long, ...) -> libc::c_long; + } + + const SYS_GETRANDOM: libc::c_long = 143; + const GRND_NONBLOCK: libc::c_uint = 0x0001; + const GRND_RANDOM: libc::c_uint = 0x0002; + + unsafe { + syscall(SYS_GETRANDOM, buf.as_mut_ptr(), buf.len(), + if blocking { 0 } else { GRND_NONBLOCK } | GRND_RANDOM) + } + } + + fn getrandom_try_fill(dest: &mut [u8], blocking: bool) -> Result<(), Error> { + let result = getrandom(dest, blocking); + if result == -1 || result == 0 { + let err = io::Error::last_os_error(); + let kind = err.kind(); + if kind == io::ErrorKind::WouldBlock { + return Err(Error::with_cause( + ErrorKind::NotReady, + "getrandom not ready", + err, + )); + } else { + return Err(Error::with_cause( + ErrorKind::Unavailable, + "unexpected getrandom error", + err, + )); + } + } else if result != dest.len() as i64 { + return Err(Error::new(ErrorKind::Unavailable, + "unexpected getrandom error")); + } + Ok(()) + } + + fn is_getrandom_available() -> bool { + use std::sync::atomic::{AtomicBool, ATOMIC_BOOL_INIT, Ordering}; + use std::sync::{Once, ONCE_INIT}; + + static CHECKER: Once = ONCE_INIT; + static AVAILABLE: AtomicBool = ATOMIC_BOOL_INIT; + + CHECKER.call_once(|| { + debug!("OsRng: testing getrandom"); + let mut buf: [u8; 0] = []; + let result = getrandom(&mut buf, false); + let available = if result == -1 { + let err = io::Error::last_os_error().raw_os_error(); + err != Some(libc::ENOSYS) + } else { + true + }; + AVAILABLE.store(available, Ordering::Relaxed); + info!("OsRng: using {}", if available { "getrandom" } else { "/dev/random" }); + }); + + AVAILABLE.load(Ordering::Relaxed) + } +} + + +#[cfg(target_os = "cloudabi")] +mod imp { + extern crate cloudabi; + + use std::io; + use {Error, ErrorKind}; + use super::OsRngImpl; + + #[derive(Clone, Debug)] + pub struct OsRng; + + impl OsRngImpl for OsRng { + fn new() -> Result<OsRng, Error> { Ok(OsRng) } + + fn fill_chunk(&mut self, dest: &mut [u8]) -> Result<(), Error> { + let errno = unsafe { cloudabi::random_get(dest) }; + if errno == cloudabi::errno::SUCCESS { + Ok(()) + } else { + // Cloudlibc provides its own `strerror` implementation so we + // can use `from_raw_os_error` here. + Err(Error::with_cause( + ErrorKind::Unavailable, + "random_get() system call failed", + io::Error::from_raw_os_error(errno as i32), + )) + } + } + + fn method_str(&self) -> &'static str { "cloudabi::random_get" } + } +} + + +#[cfg(any(target_os = "macos", target_os = "ios"))] +mod imp { + extern crate libc; + + use {Error, ErrorKind}; + use super::OsRngImpl; + + use std::io; + use self::libc::{c_int, size_t}; + + #[derive(Clone, Debug)] + pub struct OsRng; + + enum SecRandom {} + + #[allow(non_upper_case_globals)] + const kSecRandomDefault: *const SecRandom = 0 as *const SecRandom; + + #[link(name = "Security", kind = "framework")] + extern { + fn SecRandomCopyBytes(rnd: *const SecRandom, + count: size_t, bytes: *mut u8) -> c_int; + } + + impl OsRngImpl for OsRng { + fn new() -> Result<OsRng, Error> { Ok(OsRng) } + + fn fill_chunk(&mut self, dest: &mut [u8]) -> Result<(), Error> { + let ret = unsafe { + SecRandomCopyBytes(kSecRandomDefault, + dest.len() as size_t, + dest.as_mut_ptr()) + }; + if ret == -1 { + Err(Error::with_cause( + ErrorKind::Unavailable, + "couldn't generate random bytes", + io::Error::last_os_error())) + } else { + Ok(()) + } + } + + fn method_str(&self) -> &'static str { "SecRandomCopyBytes" } + } +} + + +#[cfg(target_os = "freebsd")] +mod imp { + extern crate libc; + + use {Error, ErrorKind}; + use super::OsRngImpl; + + use std::ptr; + use std::io; + + #[derive(Clone, Debug)] + pub struct OsRng; + + impl OsRngImpl for OsRng { + fn new() -> Result<OsRng, Error> { Ok(OsRng) } + + fn fill_chunk(&mut self, dest: &mut [u8]) -> Result<(), Error> { + let mib = [libc::CTL_KERN, libc::KERN_ARND]; + let mut len = dest.len(); + let ret = unsafe { + libc::sysctl(mib.as_ptr(), mib.len() as libc::c_uint, + dest.as_mut_ptr() as *mut _, &mut len, + ptr::null(), 0) + }; + if ret == -1 || len != dest.len() { + return Err(Error::with_cause( + ErrorKind::Unavailable, + "kern.arandom sysctl failed", + io::Error::last_os_error())); + } + Ok(()) + } + + fn max_chunk_size(&self) -> usize { 256 } + + fn method_str(&self) -> &'static str { "kern.arandom" } + } +} + + +#[cfg(any(target_os = "openbsd", target_os = "bitrig"))] +mod imp { + extern crate libc; + + use {Error, ErrorKind}; + use super::OsRngImpl; + + use std::io; + + #[derive(Clone, Debug)] + pub struct OsRng; + + impl OsRngImpl for OsRng { + fn new() -> Result<OsRng, Error> { Ok(OsRng) } + + fn fill_chunk(&mut self, dest: &mut [u8]) -> Result<(), Error> { + let ret = unsafe { + libc::getentropy(dest.as_mut_ptr() as *mut libc::c_void, dest.len()) + }; + if ret == -1 { + return Err(Error::with_cause( + ErrorKind::Unavailable, + "getentropy failed", + io::Error::last_os_error())); + } + Ok(()) + } + + fn max_chunk_size(&self) -> usize { 256 } + + fn method_str(&self) -> &'static str { "getentropy" } + } +} + + +#[cfg(target_os = "redox")] +mod imp { + use Error; + use super::random_device; + use super::OsRngImpl; + use std::fs::File; + + #[derive(Clone, Debug)] + pub struct OsRng(); + + impl OsRngImpl for OsRng { + fn new() -> Result<OsRng, Error> { + random_device::open("rand:", &|p| File::open(p))?; + Ok(OsRng()) + } + + fn fill_chunk(&mut self, dest: &mut [u8]) -> Result<(), Error> { + random_device::read(dest) + } + + fn method_str(&self) -> &'static str { "'rand:'" } + } +} + + +#[cfg(target_os = "fuchsia")] +mod imp { + extern crate fuchsia_zircon; + + use {Error, ErrorKind}; + use super::OsRngImpl; + + #[derive(Clone, Debug)] + pub struct OsRng; + + impl OsRngImpl for OsRng { + fn new() -> Result<OsRng, Error> { Ok(OsRng) } + + fn fill_chunk(&mut self, dest: &mut [u8]) -> Result<(), Error> { + let mut read = 0; + while read < dest.len() { + match fuchsia_zircon::cprng_draw(&mut dest[read..]) { + Ok(actual) => read += actual, + Err(e) => { + return Err(Error::with_cause( + ErrorKind::Unavailable, + "cprng_draw failed", + e.into_io_error())); + } + }; + } + Ok(()) + } + + fn max_chunk_size(&self) -> usize { + fuchsia_zircon::sys::ZX_CPRNG_DRAW_MAX_LEN + } + + fn method_str(&self) -> &'static str { "cprng_draw" } + } +} + + +#[cfg(windows)] +mod imp { + extern crate winapi; + + use {Error, ErrorKind}; + use super::OsRngImpl; + + use std::io; + + use self::winapi::shared::minwindef::ULONG; + use self::winapi::um::ntsecapi::RtlGenRandom; + use self::winapi::um::winnt::PVOID; + + #[derive(Clone, Debug)] + pub struct OsRng; + + impl OsRngImpl for OsRng { + fn new() -> Result<OsRng, Error> { Ok(OsRng) } + + fn fill_chunk(&mut self, dest: &mut [u8]) -> Result<(), Error> { + let ret = unsafe { + RtlGenRandom(dest.as_mut_ptr() as PVOID, dest.len() as ULONG) + }; + if ret == 0 { + return Err(Error::with_cause( + ErrorKind::Unavailable, + "couldn't generate random bytes", + io::Error::last_os_error())); + } + Ok(()) + } + + fn max_chunk_size(&self) -> usize { <ULONG>::max_value() as usize } + + fn method_str(&self) -> &'static str { "RtlGenRandom" } + } +} + + +#[cfg(all(target_arch = "wasm32", + not(target_os = "emscripten"), + feature = "stdweb"))] +mod imp { + use std::mem; + use stdweb::unstable::TryInto; + use stdweb::web::error::Error as WebError; + use {Error, ErrorKind}; + use super::OsRngImpl; + + #[derive(Clone, Debug)] + enum OsRngMethod { + Browser, + Node + } + + #[derive(Clone, Debug)] + pub struct OsRng(OsRngMethod); + + impl OsRngImpl for OsRng { + fn new() -> Result<OsRng, Error> { + let result = js! { + try { + if ( + typeof self === "object" && + typeof self.crypto === "object" && + typeof self.crypto.getRandomValues === "function" + ) { + return { success: true, ty: 1 }; + } + + if (typeof require("crypto").randomBytes === "function") { + return { success: true, ty: 2 }; + } + + return { success: false, error: new Error("not supported") }; + } catch(err) { + return { success: false, error: err }; + } + }; + + if js!{ return @{ result.as_ref() }.success } == true { + let ty = js!{ return @{ result }.ty }; + + if ty == 1 { Ok(OsRng(OsRngMethod::Browser)) } + else if ty == 2 { Ok(OsRng(OsRngMethod::Node)) } + else { unreachable!() } + } else { + let err: WebError = js!{ return @{ result }.error }.try_into().unwrap(); + Err(Error::with_cause(ErrorKind::Unavailable, "WASM Error", err)) + } + } + + + fn fill_chunk(&mut self, dest: &mut [u8]) -> Result<(), Error> { + assert_eq!(mem::size_of::<usize>(), 4); + + let len = dest.len() as u32; + let ptr = dest.as_mut_ptr() as i32; + + let result = match self.0 { + OsRngMethod::Browser => js! { + try { + let array = new Uint8Array(@{ len }); + self.crypto.getRandomValues(array); + HEAPU8.set(array, @{ ptr }); + + return { success: true }; + } catch(err) { + return { success: false, error: err }; + } + }, + OsRngMethod::Node => js! { + try { + let bytes = require("crypto").randomBytes(@{ len }); + HEAPU8.set(new Uint8Array(bytes), @{ ptr }); + + return { success: true }; + } catch(err) { + return { success: false, error: err }; + } + } + }; + + if js!{ return @{ result.as_ref() }.success } == true { + Ok(()) + } else { + let err: WebError = js!{ return @{ result }.error }.try_into().unwrap(); + Err(Error::with_cause(ErrorKind::Unexpected, "WASM Error", err)) + } + } + + fn max_chunk_size(&self) -> usize { 65536 } + + fn method_str(&self) -> &'static str { + match self.0 { + OsRngMethod::Browser => "Crypto.getRandomValues", + OsRngMethod::Node => "crypto.randomBytes", + } + } + } +} + +#[cfg(all(target_arch = "wasm32", + not(target_os = "emscripten"), + not(feature = "stdweb"), + feature = "wasm-bindgen"))] +mod imp { + use __wbg_shims::*; + + use {Error, ErrorKind}; + use super::OsRngImpl; + + #[derive(Clone, Debug)] + pub enum OsRng { + Node(NodeCrypto), + Browser(BrowserCrypto), + } + + impl OsRngImpl for OsRng { + fn new() -> Result<OsRng, Error> { + // First up we need to detect if we're running in node.js or a + // browser. To do this we get ahold of the `this` object (in a bit + // of a roundabout fashion). + // + // Once we have `this` we look at its `self` property, which is + // only defined on the web (either a main window or web worker). + let this = Function::new("return this").call(&JsValue::undefined()); + assert!(this != JsValue::undefined()); + let this = This::from(this); + let is_browser = this.self_() != JsValue::undefined(); + + if !is_browser { + return Ok(OsRng::Node(node_require("crypto"))) + } + + // If `self` is defined then we're in a browser somehow (main window + // or web worker). Here we want to try to use + // `crypto.getRandomValues`, but if `crypto` isn't defined we assume + // we're in an older web browser and the OS RNG isn't available. + let crypto = this.crypto(); + if crypto.is_undefined() { + let msg = "self.crypto is undefined"; + return Err(Error::new(ErrorKind::Unavailable, msg)) + } + + // Test if `crypto.getRandomValues` is undefined as well + let crypto: BrowserCrypto = crypto.into(); + if crypto.get_random_values_fn().is_undefined() { + let msg = "crypto.getRandomValues is undefined"; + return Err(Error::new(ErrorKind::Unavailable, msg)) + } + + // Ok! `self.crypto.getRandomValues` is a defined value, so let's + // assume we can do browser crypto. + Ok(OsRng::Browser(crypto)) + } + + fn fill_chunk(&mut self, dest: &mut [u8]) -> Result<(), Error> { + match *self { + OsRng::Node(ref n) => n.random_fill_sync(dest), + OsRng::Browser(ref n) => n.get_random_values(dest), + } + Ok(()) + } + + fn max_chunk_size(&self) -> usize { + match *self { + OsRng::Node(_) => usize::max_value(), + OsRng::Browser(_) => { + // see https://developer.mozilla.org/en-US/docs/Web/API/Crypto/getRandomValues + // + // where it says: + // + // > A QuotaExceededError DOMException is thrown if the + // > requested length is greater than 65536 bytes. + 65536 + } + } + } + + fn method_str(&self) -> &'static str { + match *self { + OsRng::Node(_) => "crypto.randomFillSync", + OsRng::Browser(_) => "crypto.getRandomValues", + } + } + } +} + + +#[cfg(test)] +mod test { + use RngCore; + use super::OsRng; + + #[test] + fn test_os_rng() { + let mut r = OsRng::new().unwrap(); + + r.next_u32(); + r.next_u64(); + + let mut v1 = [0u8; 1000]; + r.fill_bytes(&mut v1); + + let mut v2 = [0u8; 1000]; + r.fill_bytes(&mut v2); + + let mut n_diff_bits = 0; + for i in 0..v1.len() { + n_diff_bits += (v1[i] ^ v2[i]).count_ones(); + } + + // Check at least 1 bit per byte differs. p(failure) < 1e-1000 with random input. + assert!(n_diff_bits >= v1.len() as u32); + } + + #[test] + fn test_os_rng_empty() { + let mut r = OsRng::new().unwrap(); + + let mut empty = [0u8; 0]; + r.fill_bytes(&mut empty); + } + + #[test] + fn test_os_rng_huge() { + let mut r = OsRng::new().unwrap(); + + let mut huge = [0u8; 100_000]; + r.fill_bytes(&mut huge); + } + + #[cfg(not(any(target_arch = "wasm32", target_arch = "asmjs")))] + #[test] + fn test_os_rng_tasks() { + use std::sync::mpsc::channel; + use std::thread; + + let mut txs = vec!(); + for _ in 0..20 { + let (tx, rx) = channel(); + txs.push(tx); + + thread::spawn(move|| { + // wait until all the tasks are ready to go. + rx.recv().unwrap(); + + // deschedule to attempt to interleave things as much + // as possible (XXX: is this a good test?) + let mut r = OsRng::new().unwrap(); + thread::yield_now(); + let mut v = [0u8; 1000]; + + for _ in 0..100 { + r.next_u32(); + thread::yield_now(); + r.next_u64(); + thread::yield_now(); + r.fill_bytes(&mut v); + thread::yield_now(); + } + }); + } + + // start all the tasks + for tx in txs.iter() { + tx.send(()).unwrap(); + } + } +} |