Re: [PATCH 0/3] userfaultfd: allow to forbid unprivileged users

Mike Kravetz
2019-03-13T20:01:40Z

On 3/13/19 11:52 AM, Andrea Arcangeli wrote:
>
> hugetlbfs is more complicated to detect, because even if you inherit
> it from fork(), the services that mounts the fs may be in a different
> container than the one that Oracle that uses userfaultfd later on down
> the road from a different context. And I don't think it would be ok to
> allow running userfaultfd just because you can open a file in an
> hugetlbfs file system. With /dev/kvm it's a bit different, that's
> chmod o-r by default.. no luser should be able to open it.
>
> Unless somebody suggests a consistent way to make hugetlbfs "just
> work" (like we could achieve clean with CRIU and KVM), I think Oracle
> will need a one liner change in the Oracle setup to echo into that
> file in addition of running the hugetlbfs mount.

I think you are suggesting the DB setup process enable uffd for all users.
Correct?

This may be too simple, and I don't really like group access, but how about
just defining a uffd group? If you are in the group you can make uffd
system calls.
--
Mike Kravetz