linux-kernel - Re: [PATCH] selinux: deprecated fs ocon

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Message-ID: <CAHC9VhQ_yLL432Ete+ZB3TV-wwG7capXCOE1NKY029evKxQ9DA@mail.gmail.com>
Date:   Tue, 23 May 2023 15:38:59 -0400
From:   Paul Moore <paul@...l-moore.com>
To:     Christian Göttsche <cgzones@...glemail.com>
Cc:     selinux@...r.kernel.org,
        Stephen Smalley <stephen.smalley.work@...il.com>,
        Eric Paris <eparis@...isplace.org>,
        Xiu Jianfeng <xiujianfeng@...wei.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] selinux: deprecated fs ocon

On Tue, May 23, 2023 at 2:25 PM Christian Göttsche
<cgzones@...glemail.com> wrote:
> On Thu, 18 May 2023 at 22:18, Paul Moore <paul@...l-moore.com> wrote:
> > On Thu, May 18, 2023 at 1:56 PM Paul Moore <paul@...l-moore.com> wrote:
> > > On May 11, 2023 =?UTF-8?q?Christian=20G=C3=B6ttsche?= <cgzones@...glemail.com> wrote:
> > > >
> > > > The object context type `fs`, not to be confused with the well used
> > > > object context type `fscon`, was introduced in the initial git commit
> > > > 1da177e4c3f4 ("Linux-2.6.12-rc2") but never actually used since.
> > > >
> > > > The paper "A Security Policy Configuration for the Security-Enhanced
> > > > Linux" [1] mentions it under `7.2 File System Contexts` but also states:
> > > >
> > > >     Currently, this configuration is unused.
> > > >
> > > > The policy statement defining such object contexts is `fscon`, e.g.:
> > > >
> > > >     fscon 2 3 gen_context(system_u:object_r:conA_t,s0) gen_context(system_u:object_r:conB_t,s0)
> > > >
> > > > It is not documented at selinuxproject.org or in the SELinux notebook
> > > > and not supported by the Reference Policy buildsystem - the statement is
> > > > not properly sorted - and thus not used in the Reference or Fedora
> > > > Policy.
> > > >
> > > > Print a warning message at policy load for each such object context:
> > > >
> > > >     SELinux:  void and deprecated fs ocon 02:03
> > > >
> > > > This topic was initially highlighted by Nicolas Iooss [2].
> > > >
> > > > [1]: https://media.defense.gov/2021/Jul/29/2002815735/-1/-1/0/SELINUX-SECURITY-POLICY-CONFIGURATION-REPORT.PDF
> > > > [2]: https://lore.kernel.org/selinux/CAJfZ7=mP2eJaq2BfO3y0VnwUJaY2cS2p=HZMN71z1pKjzaT0Eg@mail.gmail.com/
> > > >
> > > > Signed-off-by: Christian Göttsche <cgzones@...glemail.com>
> > > > ---
> > > >  security/selinux/ss/policydb.c | 4 ++++
> > > >  security/selinux/ss/policydb.h | 2 +-
> > > >  2 files changed, 5 insertions(+), 1 deletion(-)
> > >
> > > Thanks, this is a nice catch, although some minor suggestions below ...
> > >
> > > > diff --git a/security/selinux/ss/policydb.c b/security/selinux/ss/policydb.c
> > > > index 97c0074f9312..31b08b34c722 100644
> > > > --- a/security/selinux/ss/policydb.c
> > > > +++ b/security/selinux/ss/policydb.c
> > > > @@ -2257,6 +2257,10 @@ static int ocontext_read(struct policydb *p, const struct policydb_compat_info *
> > > >                               if (rc)
> > > >                                       goto out;
> > > >
> > > > +                             if (i == OCON_FS)
> > > > +                                     pr_warn("SELinux:  void and deprecated fs ocon %s\n",
> > > > +                                             c->u.name);
> > >
> > > Instead of having to check if 'i == OCON_FS', why not simply put the
> > > pr_warn() call up in the OCON_FS case block on line ~2249 and let it
> > > continue to fallthrough to the OCON_NETIF block?
> >
> > Bah, nevermind, you need to leave it here because of the 'c->u.name'
> > in the pr_warn().  If you're okay with me adjusting the deprecation
> > comment (below) during the merge I'll can merge this now ... ?
>
> Yes, please feel free to adjust the inline comment.

Okay, done and merged into selinux/next, thanks.

-- 
paul-moore.com