1 files changed, 43 insertions, 0 deletions
diff --git a/rust/kernel/src/random.rs b/rust/kernel/src/random.rs
new file mode 100644
index 000000000000..bd80c835749d
--- /dev/null
+++ b/rust/kernel/src/random.rs
@@ -0,0 +1,43 @@
+// SPDX-License-Identifier: GPL-2.0
+
+use core::convert::TryInto;
+
+use crate::{bindings, c_types, error};
+
+/// Fills `dest` 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's ready.
+pub fn getrandom(dest: &mut [u8]) -> error::KernelResult<()> {
+    let res = unsafe { bindings::wait_for_random_bytes() };
+    if res != 0 {
+        return Err(error::Error::from_kernel_errno(res));
+    }
+
+    unsafe {
+        bindings::get_random_bytes(
+            dest.as_mut_ptr() as *mut c_types::c_void,
+            dest.len().try_into()?,
+        );
+    }
+    Ok(())
+}
+
+/// Fills `dest` 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]) -> error::KernelResult<()> {
+    if !unsafe { bindings::rng_is_initialized() } {
+        return Err(error::Error::EAGAIN);
+    }
+    getrandom(dest)
+}
+
+/// Contributes the contents of `data` 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().try_into().unwrap(),
+        );
+    }
+}