CHERIoT-Platform/network-stack

Put the device MAC address into a pre-shared read-only variable in the firewall

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#52 opened on Nov 19, 2024

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good first issue

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Description

Currently the device MAC is generated and stored in the firewall, and accessible by other compartments through firewall_mac_address_get.

A downside of having to retrieve a copy through firewall_mac_address_get is that the resulting copy increases the state of compartments, and is yet another thing that must be reset if a compartment crashes ("reset critical"). See the discussion in https://github.com/CHERIoT-Platform/network-stack/pull/50.

Instead, it would be desirable to put the device MAC address into a pre-shared read-only variable in the firewall.

Contributor guide

Research direction
Study how the firewall compartment currently uses `firewall mac address get` and how other compartments retrieve the MAC. Then, research how to define a pre shared read only variable within the firewall compartment that is accessible via capability based sharing. Review existing examples of immutable global data in CHERIoT compartments and consider the necessary changes to the build system and API.
Tech stack
None
Domain
backend
Issue type
Refactor
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Mostly clear
Prerequisites
CHERIoT programming modelC++compartment memory model
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
50