Set permissions/ownership when creating a socket

[Dreamsorcerer]

Feature or enhancement

When creating a socket with one of the asyncio methods, it should be possible to specify the correct ownership/permissions needed for good security.

Pitch

When creating a server with loop.create_unix_server(), it will create the socket with default permissions which may lack security or may not be accessible to the application that is meant to communicate via this socket.

Previous discussion

python/asyncio#426

Linked PRs

• gh-94984: Add mode parameter to create_unix_server() #155086

[kumaraditya303]

Can't you do this by calling os.chmod after binding the socket?

[Dreamsorcerer]

Yes, see the original (archived) issue linked.

The behaviour is not desirable, and could potentially lead to security issues. If you can create a file with the correct permissions, why would you not be able to create a named socket with the correct permissions?

e.g. os.open allows setting the permissions on creation: https://docs.python.org/3/library/os.html#os.open

[gvanrossum]

Possibly because there's no platform-independent way to do it? (I think I gleaned this from the original issue.)

Anyway, I'd be happy to review a PR, but I'm not the expert here. @Dreamsorcerer are you interested in submitting a PR?

[Dreamsorcerer]

Not currently, got a hundred things to catch up on with aiohttp etc. Mainly just wanted to make sure the request didn't get lost. Maybe I'll get some time to come back to it at some point though.

[gvanrossum]

No worries, hopefully someone else with relevant knowledge will help us out.

[kumaraditya303]

@Dreamsorcerer Do you still want to pursue this further?

[Dreamsorcerer]

@Dreamsorcerer Do you still want to pursue this further?

How do you feel about the os.chmod() proposal in the original issue? If we add the call between the bind() and listen(), then any connections before the permissions are set would be refused anyway, so that likely minimises the security implications.

[kumaraditya303]

Yeah, that sounds good to me.