[Feature Request] host-uds=all with support for SCM_RIGHTS FD sharing.

[handpickencounter]

When using -host-uds=all allow for -host-uds=all,fdshare or similar enabling sharing of FDs across a UDS which crosses the gvisor boundary back and forth through the use of SCM_RIGHTS.

Will allow for protocols which utilize SCM_RIGHTS to share mmap'ed FDs to work between gvisor instances and gvisor<>host.

[nixprime]

It's not possible to send arbitrary FDs from sandbox to host via SCM_RIGHTS since many in-sandbox files are implemented internal to gVisor and won't have host FDs. Do you have a specific use case?

[handpickencounter]

The Wayland protocol shares memory blobs with SCM_RIGHTS across a UDS socket.