[PATCH] security/landlock: use square brackets around "landlock-ruleset"

[Ondrej Mosnacek]

On Tue, Oct 12, 2021 at 8:12 PM Paul Moore <paul at paul-moore.com> wrote:
> On Tue, Oct 12, 2021 at 6:38 AM Christian Brauner
> <christian.brauner at ubuntu.com> wrote:
> > On Mon, Oct 11, 2021 at 04:38:55PM +0200, Mickaël Salaün wrote:
> > > On 11/10/2021 15:37, Christian Brauner wrote:
> > > > From: Christian Brauner <christian.brauner at ubuntu.com>
> > > >
> > > > Make the name of the anon inode fd "[landlock-ruleset]" instead of
> > > > "landlock-ruleset". This is minor but most anon inode fds already
> > > > carry square brackets around their name:
> > > >
> > > >     [eventfd]
> > > >     [eventpoll]
> > > >     [fanotify]
> > > >     [fscontext]
> > > >     [io_uring]
> > > >     [pidfd]
> > > >     [signalfd]
> > > >     [timerfd]
> > > >     [userfaultfd]
> > > >
> > > > For the sake of consistency lets do the same for the landlock-ruleset anon
> > > > inode fd that comes with landlock. We did the same in
> > > > 1cdc415f1083 ("uapi, fsopen: use square brackets around "fscontext" [ver #2]")
> > > > for the new mount api.
> > >
> > > Before creating "landlock-ruleset" FD, I looked at other anonymous FD
> > > and saw this kind of inconsistency. I don't get why we need to add extra
> > > characters to names, those brackets seem useless. If it should be part
> >
> > Past inconsistency shouldn't justify future inconsistency. If you have a
> > strong opinion about this for landlock I'm not going to push for it.
> > Exchanging more than 2-3 email about something like this seems too much.
>
> [NOTE: adding the SELinux list as well as Chris (SELinux refrence
> policy maintainer) and Petr (Fedora/RHEL SELinux)]
>
> Chris and Petr, do either of you currently have any policy that
> references the "landlock-ruleset" anonymous inode?  In other words,
> would adding the brackets around the name cause you any problems?

AFAIU, the anon_inode transitions (the only mechanism where the "file
name" would be exposed to the policy) are done only for inodes created
by anon_inode_getfd_secure(), which is currently only used by
userfaultfd. So you don't even need to ask that question; at this
point it should be safe to change any of the names except
"[userfaultfd]" as far as SELinux policy is concerned.

-- 
Ondrej Mosnacek
Software Engineer, Linux Security - SELinux kernel
Red Hat, Inc.