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

Richard Guy Briggs
2018-09-14T15:16:43Z

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 =<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= 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.

> > old - the old value
> > new - the new value
> >
> > Signed-off-by: Ondrej Mosnacek <omosnace@redhat.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
>
> --
> paul moore
> www.paul-moore.com

- RGB

--
Richard Guy Briggs <rgb@redhat.com>
Sr. S/W Engineer, Kernel Security, Base Operating Systems
Remote, Ottawa, Red Hat Canada
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