1 files changed, 42 insertions, 0 deletions
diff --git a/rust/kernel/random.rs b/rust/kernel/random.rs
new file mode 100644
index 000000000000..a0926cb68a75
--- /dev/null
+++ b/rust/kernel/random.rs
@@ -0,0 +1,42 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Random numbers.
+//!
+//! C header: [`include/linux/random.h`](../../../../include/linux/random.h)
+
+use crate::{bindings, c_types, error::code::*, Error, Result};
+
+/// Fills a byte slice with random bytes generated from the kernel's CSPRNG.
+///
+/// Ensures that the CSPRNG has been seeded before generating any random bytes,
+/// and will block until it is ready.
+pub fn getrandom(dest: &mut [u8]) -> Result {
+    let res = unsafe { bindings::wait_for_random_bytes() };
+    if res != 0 {
+        return Err(Error::from_kernel_errno(res));
+    }
+
+    unsafe {
+        bindings::get_random_bytes(dest.as_mut_ptr() as *mut c_types::c_void, dest.len());
+    }
+    Ok(())
+}
+
+/// Fills a byte slice with random bytes generated from the kernel's CSPRNG.
+///
+/// If the CSPRNG is not yet seeded, returns an `Err(EAGAIN)` immediately.
+pub fn getrandom_nonblock(dest: &mut [u8]) -> Result {
+    if !unsafe { bindings::rng_is_initialized() } {
+        return Err(EAGAIN);
+    }
+    getrandom(dest)
+}
+
+/// Contributes the contents of a byte slice to the kernel's entropy pool.
+///
+/// Does *not* credit the kernel entropy counter though.
+pub fn add_randomness(data: &[u8]) {
+    unsafe {
+        bindings::add_device_randomness(data.as_ptr() as *const c_types::c_void, data.len());
+    }
+}