Re: [RFC PATCH 6/9] audit: rework audit_log_start()

[Richard Guy Briggs <rgb@redhat.com>]

On 2016-11-25 11:38, Paul Moore wrote:
> On Thu, Nov 24, 2016 at 1:41 AM, Richard Guy Briggs <rgb@redhat.com> wrote:
> > On 2016-11-23 20:42, Paul Moore wrote:
> >> From: Paul Moore <paul@paul-moore.com>
> >>
> >> The backlog queue handling in audit_log_start() is a little odd with
> >> some questionable design decisions, this patch attempts to rectify
> >> this with the following changes:
> >>
> >> * Never make auditd wait, ignore any backlog limits as we need auditd
> >> awake so it can drain the backlog queue.
> >>
> >> * When we hit a backlog limit and start dropping records, don't wake
> >> all the tasks sleeping on the backlog, that's silly.  Instead, let
> >> kauditd_thread() take care of waking everyone once it has had a chance
> >> to drain the backlog queue.
> >>
> >> * Don't keep a global backlog timeout countdown, make it per-task.  A
> >> per-task timer means we won't have all the sleeping tasks waking at
> >> the same time and hammering on an already stressed backlog queue.
> >>
> >> Signed-off-by: Paul Moore <paul@paul-moore.com>
> >> ---
> >>  kernel/audit.c |   92 ++++++++++++++++++++++----------------------------------
> 
> ...
> 
> >>  1 file changed, 36 insertions(+), 56 deletions(-)
> >> +     /* don't ever fail/sleep on auditd since we need auditd to drain the
> >> +      * queue; also, when we are checking for auditd, compare PIDs using
> >> +      * task_tgid_vnr() since auditd_pid is set in audit_receive_msg() using
> >> +      * a PID anchored in the caller's namespace */
> >> +     if (!(audit_pid && audit_pid == task_tgid_vnr(current))) {
> >
> > Could the change from task_tgid() [should be same as current->tgid] to
> > task_tgid_vnr() be pulled out into a seperate patch to make the
> > namespace behaviour change implicaiton much more clear?
> 
> Considering the comment above the if-conditional I don't think there
> is much to be gained by splitting it out to a separate patch.

Except the ability to find it when someone goes looking for things that
change namespace behaviour, which this patch objective should not
include.

I agree it is well explained in the comment, but that change is
unrelated to the goal of the rest of the patch.

> paul moore

- RGB

--
Richard Guy Briggs <rgb@redhat.com>
Kernel Security Engineering, Base Operating Systems, Red Hat
Remote, Ottawa, Canada
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