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Diffstat (limited to 'rand/rand_os/src/linux_android.rs')
| -rw-r--r-- | rand/rand_os/src/linux_android.rs | 182 |
1 files changed, 182 insertions, 0 deletions
diff --git a/rand/rand_os/src/linux_android.rs b/rand/rand_os/src/linux_android.rs new file mode 100644 index 0000000..9622f93 --- /dev/null +++ b/rand/rand_os/src/linux_android.rs @@ -0,0 +1,182 @@ +// Copyright 2018 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. + +//! Implementation for Linux / Android + +extern crate libc; + +use rand_core::{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) +} |