doc: update docs for entropy to mention aws-lc-rs

Modify the documentation to point to aws-lc-rs as a source of random
bytes for virtio-rng, instead of the host Linux kernel.

Signed-off-by: Babis Chalios <[email protected]>

Author: bchalios

docs/entropy.md

@@ -53,10 +53,8 @@ be achieved by adding a section like this:
 }
 ```
 
-On the host side, firecracker uses [`OsRng`][2] to get random bytes from the
-host kernel. The [implementation][3] of `OsRng` on Linux uses the
-`getrandom(2)` system call when available, otherwise it falls back to
-`/dev/urandom` after successfully polling `/dev/random`.
+On the host side, Firecracker relies on [`aws-lc-rs`][2] to retrieve the random bytes.
+`aws-lc-rs` uses the [`AWS-LC` cryptographic library][3].
 
 ## Prerequisites
 
@@ -66,5 +64,5 @@ kernel configuration option is `CONFIG_HW_RANDOM_VIRTIO` (which depends on
 `CONFIG_HW_RANDOM` and `CONFIG_VIRTIO`).
 
 [1]: https://docs.oasis-open.org/virtio/virtio/v1.2/cs01/virtio-v1.2-cs01.html#x1-3050004
-[2]: https://docs.rs/rand/latest/rand/rngs/struct.OsRng.html
-[3]: https://docs.rs/getrandom/latest/getrandom/
+[2]: https://docs.rs/aws-lc-rs/latest/aws_lc_rs/index.html
+[3]: https://github.com/aws/aws-lc

docs/snapshotting/random-for-clones.md

@@ -18,9 +18,8 @@ The Linux kernel exposes three main `RNG` interfaces to userspace: the
 `/dev/random` and `/dev/urandom` special devices, and the `getrandom` syscall,
 which are described in the [random(7) man page][1]. Moreover, Firecracker
 supports the [`virtio-rng`](../entropy.md) device which can provide additional
-entropy to guest VMs. It draws its random bytes from the host kernel via
-`getrandom` or `/dev/urandom` after ensuring that the entropy pool has been
-initialized.
+entropy to guest VMs. It draws its random bytes from the [`aws-lc-rs`][8] crate
+which wraps the [`AWS-LC` cryptographic library][9].
 
 Traditionally, `/dev/random` has been considered a source of “true”
 randomness, with the downside that reads block when the pool of entropy
@@ -237,3 +236,5 @@ int main(int argc, char ** argv) {
 [5]: https://elixir.bootlin.com/linux/v4.14.295/source/drivers/char/random.c#L1355
 [6]: https://elixir.bootlin.com/linux/v5.10.147/source/drivers/char/random.c#L1360
 [7]: https://elixir.bootlin.com/linux/v4.14.295/source/drivers/char/random.c#L1351
+[8]: https://docs.rs/aws-lc-rs/latest/aws_lc_rs/index.html
+[9]: https://github.com/aws/aws-lc