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Kernel version 6.3 adds support for sending the user supplementary groups (Bug 2134128):

https://lore.kernel.org/lkml/Y%2FzYyN7NeLKusmSj@miu.piliscsaba.redhat.com/#r

The current version of virtiofsd only implements a workaround to this problem.
It keeps CAP_DAC_OVERRIDE after switching uid/gid (Bug 2141629), but this trick doesn't work over NFS or CephFS. This is also required to fix https://issues.redhat.com/browse/KATA-1776

How reproducible:
100%

Steps to Reproduce:
1. start virtiofsd over a NFS shared dir
root# virtiofsd --shared-dir=/.../some_nfs_shared_dir ...

2. start the guest.

3. (in guest) mount the virtiofs
root#  mount -t virtiofs myfs /mnt

4. (in guest) add a user and it to the wheel group (as supplementary group)
root# useradd u1
root# passwd u1
root# usermod -G wheel u1

5. (in guest) as root, create a test directory
root# mkdir -m 0770 testdir
root# chgrp wheel testdir

6. (in guest) switch to u1 user and try to create a file inside the test directory
root# su u1
u1$ touch testdir/file


Actual results:
fails with "Permission denied"

Expected results:
# ls -l testdir/file 
-rw-r--r-- 1 user user 0 nov 10 11:12 testdir/file

Test with kernel pkg in https://bugzilla.redhat.com/show_bug.cgi?id=2134128#c14 together, the result is good with no permission issue with nfs as the virtiofs backend.
So preverify it.

Anyone who can help update the 'Fixed in Version' field with the build nvr please ? Thanks!

Verify this bug with virtiofsd-1.7.

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (virtiofsd bug fix and enhancement update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2023:6522