linux-kernel - Re: [PATCH ghak10 v5 1/2] audit: Add functions to log time adjustments

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Message-ID: <20180914162403.d2njtt2cp7slbcsw@madcap2.tricolour.ca>
Date:   Fri, 14 Sep 2018 12:24:03 -0400
From:   Richard Guy Briggs <rgb@...hat.com>
To:     Steve Grubb <sgrubb@...hat.com>
Cc:     sboyd@...nel.org, linux-kernel@...r.kernel.org,
        mlichvar@...hat.com, linux-audit@...hat.com,
        john.stultz@...aro.org, tglx@...utronix.de
Subject: Re: [PATCH ghak10 v5 1/2] audit: Add functions to log time
 adjustments

On 2018-09-14 11:34, Steve Grubb wrote:
> On Friday, September 14, 2018 11:16:43 AM EDT Richard Guy Briggs wrote:
> > On 2018-09-13 23:18, Paul Moore wrote:
> > > On Fri, Aug 24, 2018 at 8:00 AM Ondrej Mosnacek <omosnace@...hat.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.
> 
> Something like this or the other format is fine. Neither hurt parsing because 
> these are not searchable fields. We only have issues when it involves a 
> searchable field name.

Ok, fair enough.  Thanks Steve.

> HTH...
> 
> -Steve
> 
> > > >         old - the old value
> > > >         new - the new value
> > > > 
> > > > Signed-off-by: Ondrej Mosnacek <omosnace@...hat.com>
> > > > ---
> > > > 
> > > >  include/linux/audit.h      | 21 +++++++++++++++++++++
> > > >  include/uapi/linux/audit.h |  2 ++
> > > >  kernel/auditsc.c           | 15 +++++++++++++++
> > > >  3 files changed, 38 insertions(+)
> > > 
> > > A reminder that we need tests for these new records and a RFE page on the
> > > wiki:
> > > 
> > > * https://github.com/linux-audit/audit-testsuite
> > > * https://github.com/linux-audit/audit-kernel/wiki
> > 
> > - RGB

- RGB

--
Richard Guy Briggs <rgb@...hat.com>
Sr. S/W Engineer, Kernel Security, Base Operating Systems
Remote, Ottawa, Red Hat Canada
IRC: rgb, SunRaycer
Voice: +1.647.777.2635, Internal: (81) 32635