Add rng protocole

[gelven4sec]

Implementation of the EFI_RNG_PROTOCOL

For the need of a project I would need this implantation as fast as possible.

GUID

#define EFI_RNG_PROTOCOL_GUID \
{ 0x3152bca5, 0xeade, 0x433d,\
 {0x86, 0x2e, 0xc0, 0x1c, 0xdc, 0x29, 0x1f, 0x44}}

Protocol Interface Structure

typedef struct _EFI_RNG_PROTOCOL {
 EFI_RNG_GET_INFO GetInfo
 EFI_RNG_GET_RNG GetRNG;
} EFI_RNG_PROTOCOL;

Parameters

GetInfo Returns information about the random number generation
implementation.
GetRNG Returns the next set of random numbers.

Description

This protocol allows retrieval of RNG values from an UEFI driver. The GetInfo service returns
information about the RNG algorithms the driver supports. The GetRNG service creates a RNG value
using an (optionally specified) RNG algorithm.

[gelven4sec]

Hi guys,

I would need some help with this :

So I'm just trying to instantiate the Rng I just created and it's failing with the status UNSUPPORTED.
I'm really new about UEFI and everything that's behind the wrapper, so I would be glad that you tell me what i'm doing wrong.

[nicholasbishop]

Thanks for the PR :)

So I'm just trying to instantiate the Rng I just created and it's failing with the status UNSUPPORTED.

The issue here is the handle being passed to open_protocol. Handles represent resources. For example, the image handle passed into the function represents the currently-running UEFI program. In your case you want a handle that represents an rng device, so first you have to find such a handle and then pass that to open_protocol. Something like this should work:

    let handle = *bt
        .find_handles::<Rng>()
        .expect_success("Failed to get Rng handles")
        .first()
        .expect("No Rng handles");

    let rng = bt
        .open_protocol::<Rng>(
            OpenProtocolParams {
                handle,
                agent: image,
                controller: None,
            },
            OpenProtocolAttributes::Exclusive,
        )
        .expect_success("Failed to open Rng protocol");

To make this work under QEMU, you will also need to add an rng device to the virtual machine:

diff --git a/xtask/src/qemu.rs b/xtask/src/qemu.rs
index 4ecb4d1..8934316 100644
--- a/xtask/src/qemu.rs
+++ b/xtask/src/qemu.rs
@@ -277,6 +277,8 @@ pub fn run_qemu(arch: UefiArch, opt: &QemuOpt) -> Result<()> {
     // QEMU by defaults enables a ton of devices which slow down boot.
     cmd.arg("-nodefaults");
 
+    cmd.args(&["-device", "virtio-rng-pci"]);
+
     match arch {
         UefiArch::AArch64 => {
             // Use a generic ARM environment. Sadly qemu can't emulate a

[gelven4sec]

Awesome it works !

Thank you 👍

So now I just need to code the wrappers then we're good to go.

[gelven4sec]

That's it, waiting for the CI tests for last checks.

If the AArch64 CI crash again, I might need some help fixing this.

EDIT: There's still a TODO in the code, if I find some time I should implement an AlgorithmType Enum for better usability of get_info

EDIT2: You might want to link this PR to #371

[nicholasbishop]

Taking a look at the aarch64 error now, not sure what's going on there yet.

[nicholasbishop]

Looks good to me! Thanks for sticking with it through all my comments :)

For some reason the CI doesn't seem to be running, but I'll figure that out and merge it once it finishes.

[gelven4sec]

Looks good to me! Thanks for sticking with it through all my comments :)

Glad I made it :)

I will be able to present this contribution as a part of my school project.

[nicholasbishop]

Nice! Thanks again for the PR