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

[Paul Moore]

On Thu, Nov 24, 2016 at 1:41 AM, Richard Guy Briggs <rgb at redhat.com> wrote:
> On 2016-11-23 20:42, Paul Moore wrote:
>> From: Paul Moore <paul at 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 at 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.

-- 
paul moore
www.paul-moore.com