RE: Hooks for MAC

lachlanat_private

> -----Original Message-----
> From: Chris Wright [mailto:chrisat_private]
> Sent: Tuesday, July 31, 2001 8:17 AM
> To: Lachlan McIlroy
> Cc: linux-security-moduleat_private
> Subject: Re: Hooks for MAC
> 
> 
> * Lachlan McIlroy (lachlan.mcilroyat_private) wrote:
> > 
> > The attached patch contains hooks required for a MAC
> > system to moderate subject-subject control.  These hooks
> > can be used to ensure that only processes with read/write
> > label dominance can read/write attributes of another
> > process (ie GID, SID and scheduling parameters).  The
> > patch was generated from the 2.4.6 tree and I will post
> > a patch against 2.4.7 soon.
> 
> This patch applies fine to the current 2.4.7 tree, so don't worry
> about making a new patch just yet.

Thanks for the effort.

> 
> In all of setpgid, getpgid, getsid, and getscheduler you pass
> the task struct and it associated pid.  This is unecessary, as
> that's what (struct task_struct *)->pid is.  Could you please change
> this?

I'm working with SGI on this one so I included the system
call arguments for auditing purposes.  I see that they
are not necessary so I will remove all the pids but I
would like to keep the pgid in setpgid.

> 
> Do you have any need for a setsid hook?

The setsid system call operates on the current process
only.  It first scans all processes to see if it can
create a new session/group id from the current pid.  I
don't see a need to moderate processes during the scan
as no information about these processes is being returned
to the user.  (... and I have no intention of starting
another discussion about covert channels!)

> 
> The getscheduler bit (just like setscheduler) collapses the getsched
> and getparam into one.  Do you think it would be useful to distinguish
> the two?  In setscheduler, we could simply add the sched_param to the
> interface...on get*...hmmm, does it really matter?
> 

For our purposes I see no need to distinguish the
getsched and getparam calls.  Does anybody else have a
need?

The sched_param argument in getparam is an output and
can be retreived from the task_struct if required.  The
sched_param argument in setscheduler could be useful for
access control and auditing so I'll add it to the
interface.

> -chris
> 

Thanks for your input Chris.

---
Lachlan McIlroy                    Phone: +61 3 9596 4155
Trusted Linux                        Fax: +61 3 9596 2960
Adacel Technologies Ltd                    www.adacel.com

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