[RFC PATCH ghak10 v3 0/3] audit: Log modifying adjtimex(2) calls

[Paul Moore]

On Wed, Jul 18, 2018 at 3:36 PM Steve Grubb <sgrubb at redhat.com> wrote:
> On Wednesday, July 18, 2018 2:36:11 PM EDT Paul Moore wrote:
> > > Changes in v2:
> > > - The audit_adjtime() function has been modified to only log those
> > > fields that contain values that are actually used, resulting in more
> > > compact records.
> > > - The audit_adjtime() call has been moved to do_adjtimex() in
> > > timekeeping.c
> > > - Added an additional patch (for review) that simplifies the detection
> > > if the syscall is read-only.
> >
> > Looking at these new records, and trying to guess a bit at the
> > original intent of the feature request, I think we may be going a bit
> > overboard with the information we are logging.  I'm thinking all we
> > really need to capture in the audit log is the system time both before
> > and after the change (for the sake of simplicity I suggest using a
> > data format similar to the audit record timestamp).
> >
> > While I created the GH issue for this, I believe the original request
> > came from a Red Hat BZ that Steve created; Steve, what sort of
> > certification requirements (if any?) are there for logging system time
> > changes?
>
> That we record any attempts to change the system time. The problem is that
> adjtimex passes a data structure that is opaque to user space. So, we can't
> tell if someone is setting time, adjusting a tolerance, or simply retrieving
> status.
>
> With stime, we can clearly see the time that was sent into the kernel and it
> unconditionally sets time. With settimeofday, it uses a data structure that
> we cannot see, but whatever the contents are we are definitely setting time.
> Same goes for clock_settime. Only in 1 case do we actually see what the time
> is. So, that is not really needed. So, I think what we need to know is did
> the syscall do anything that adjusted the system's notion of time? And that's
> all.

So presumably my above suggestion of simply recording the system time
both before and after the change would be sufficient, yes?

-- 
paul moore
www.paul-moore.com