Subject: Re: [PATCH -v1 1/3] SECURITY: new capable_noaudit interface
From: Eric Paris <eparis@redhat.com>
To: Paul Moore <paul.moore@hp.com>
Cc: "Serge E. Hallyn" <serue@us.ibm.com>, linux-kernel@vger.kernel.org,
       selinux@tycho.nsa.gov, linux-security-module@vger.kernel.org,
       sds@tycho.nsa.gov, jmorris@nameil.org, morgan@kernel.org,
       casey@schaufler-ca.com, esandeen@redhat.com
In-Reply-To: <200810301246.20328.paul.moore@hp.com>
References: <20081029190652.31292.5901.stgit@paris.rdu.redhat.com>
	 <20081030152940.GA24853@us.ibm.com>  <200810301246.20328.paul.moore@hp.com>
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Date: Thu, 30 Oct 2008 13:17:32 -0400
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On Thu, 2008-10-30 at 12:46 -0400, Paul Moore wrote:
> On Thursday 30 October 2008 11:29:40 am Serge E. Hallyn wrote:
> > Quoting Eric Paris (eparis@redhat.com):
> > > Add a new capable interface that will be used by systems that use
> > > audit to make an A or B type decision instead of a security
> > > decision.  Currently this is the case at least for filesystems when
> > > deciding if a process can use the reserved 'root' blocks and for
> > > the case of things like the oom algorithm determining if processes
> > > are root processes and should be less likely to be killed.  These
> > > types of security system requests should not be audited or logged
> > > since they are not really security decisions.  It would be possible
> > > to solve this problem like the vm_enough_memory security check did
> > > by creating a new LSM interface and moving all of the policy into
> > > that interface but proves the needlessly bloat the LSM and provide
> > > complex indirection.
> > >
> > > This merely allows those decisions to be made where they belong and
> > > to not flood logs or printk with denials for thing that are not
> > > security decisions.
> > >
> > > Signed-off-by: Eric Paris <eparis@redhat.com>
> >
> > Please introduce some meaningful defines instead of passing 0 and 1.
> > I.e.
> >
> > #define CAP_NOAUDIT 0
> > #define CAP_AUDIT 1
> >
> > Otherwise, looks fine.
> 
> As a general rule aren't boolean arguments like this frowned upon, with 
> variations on the function preferred, i.e. something like below?
> 
>  int cap_capable(struct task_struct *tsk, int cap);
>  int cap_capable_audit(struct task_struct *tsk, int cap);

Well from outside the "security" subsystem people should call either

has_capability()
has_capability_noaudit()
or
capable()   (which calls has_capability())

How far down do I have to keep duplicating functionality to avoid
booleans?

-Eric

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