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From:   Paul Moore <paul@paul-moore.com>
Date:   Mon, 17 Sep 2018 10:36:50 -0400
Message-ID: <CAHC9VhQoBAHMU6stwH3v9cOU+QX1QDP3y-UpO35z8VtEr3Q3xQ@mail.gmail.com>
Subject: Re: [PATCH ghak10 v5 1/2] audit: Add functions to log time adjustments
To:     rgb@redhat.com
Cc:     omosnace@redhat.com, linux-audit@redhat.com, sgrubb@redhat.com,
        mlichvar@redhat.com, john.stultz@linaro.org, tglx@linutronix.de,
        sboyd@kernel.org, linux-kernel@vger.kernel.org
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On Fri, Sep 14, 2018 at 11:21 AM Richard Guy Briggs <rgb@redhat.com> wrote:
> On 2018-09-13 23:18, Paul Moore wrote:
> > On Fri, Aug 24, 2018 at 8:00 AM Ondrej Mosnacek <omosnace@redhat.com> wrote:
> > > This patch adds two auxiliary record types that will be used to annotate
> > > the adjtimex SYSCALL records with the NTP/timekeeping values that have
> > > been changed.
> > >
> > > Next, it adds two functions to the audit interface:
> > >  - audit_tk_injoffset(), which will be called whenever a timekeeping
> > >    offset is injected by a syscall from userspace,
> > >  - audit_ntp_adjust(), which will be called whenever an NTP internal
> > >    variable is changed by a syscall from userspace.
> > >
> > > Quick reference for the fields of the new records:
> > >     AUDIT_TIME_INJOFFSET
> > >         sec - the 'seconds' part of the offset
> > >         nsec - the 'nanoseconds' part of the offset
> > >     AUDIT_TIME_ADJNTPVAL
> > >         op - which value was adjusted:
> > >             offset - corresponding to the time_offset variable
> > >             freq   - corresponding to the time_freq variable
> > >             status - corresponding to the time_status variable
> > >             adjust - corresponding to the time_adjust variable
> > >             tick   - corresponding to the tick_usec variable
> > >             tai    - corresponding to the timekeeping's TAI offset
> >
> > I understand that reusing "op" is tempting, but the above aren't
> > really operations, they are state variables which are being changed.
> > Using the CONFIG_CHANGE record as a basis, I wonder if we are better
> > off with something like the following:
> >
> >  type=TIME_CHANGE <var>=<value_new> old=<value_old>
> >
> > ... you might need to preface the variable names with something like
> > "ntp_" or "offset_".  You'll notice I'm also suggesting we use a
> > single record type here; is there any reason why two records types are
> > required?
>
> Why not do something like:
>
>          type=TIME_CHANGE var=<var> new=<value_new> old=<value_old>
>
> So that we don't pollute the field namespace *and* create 8 variants on
> the same record format?  This shouldn't be much of a concern with binary
> record formats, but we're stuck with the current parsing scheme for now.

Since there is already some precedence with the "<var>=<value_new>"
format, and the field namespace is already a bit of a mess IMHO, I'd
like us to stick with the style used by CONFIG_CHANGE.

-- 
paul moore
www.paul-moore.com