Hermit is not currently supported by getrandom #199

Activity

1. newpavlov commented on Jan 17, 2021

   

   newpavlov

   on Jan 17, 2021

   Member

   More actions

   Hermit's RNG apis current don't work on aarch64, is that an issue?

   Yes, it's an issue, since it causes workarounds like this. In user code it can be worked around slightly more elegantly using the custom feature, but we can not rely on it in std. Note that currently Hermit's std simply uses a constant seed on all targets.
2. josephlr commented on Apr 29, 2021

   

   josephlr

   on Apr 29, 2021

   Last edited by josephlr

   MemberAuthor

   More actions

   I think the most reasonable approach here is the following:

   1. Simply add support for hermit using their secure_rand64 API and the hermit-abi crate. Given that hermit is a unikernel, I don't see any reason to push them for a buffer-based API (so Improve randomness syscalls hermit-os/kernel#143 isn't too important).
   2. Keep the aarch64+hermit workaround in Use getrandom for generating HashMap seed rust-lang/rust#80149 for now (to keep existing behavior).
   3. Eventually, change std's use of getrandom to emit a fallback seed if the getrandom function fails. Then, a user on aarch64-unknown-hermit will:
      • Call getrandom::getrandom, which will call secure_rand64, which will fail, causing the function to return an error.
      • The std implementation will then return a fallback seed, preserving the existing behavior.
3. newpavlov commented on Apr 30, 2021

   

   newpavlov

   on Apr 30, 2021

   Member

   More actions

   Given that hermit is a unikernel, I don't see any reason to push them for a buffer-based API

   Buffer-based API is not important here, it's the fact that Hermit randomness API always fails on ARM targets. To say the least, it's not normal and should be fixed.

   The std implementation will then return a fallback seed, preserving the existing behavior.

   I don't think it's a good behavior for all targets. It effectively means introduction of potential silent failures just because one target has an always failing randomness source.
4. josephlr

   added

   enhancementNew feature or requestNew feature or request

   waiting on upstreamWaiting for upstream changes in an external projectWaiting for upstream changes in an external project

   on Oct 23, 2022
5. josephlr commented on Feb 9, 2023

   

   josephlr

   on Feb 9, 2023

   Last edited by josephlr

   MemberAuthor

   More actions

   Fixed by #333
6. josephlr

   closed this as completedon Feb 9, 2023