why I have lost messages on boot even with very big backlog while I hunting only 2 syscalls?

[Steve Grubb]

Hello,

On Thursday, September 28, 2017 4:51:38 AM EDT Lev Olshvang wrote:
> 28.09.2017, 00:32, "Steve Grubb" <sgrubb at redhat.com>:
> > On Wednesday, September 27, 2017 4:41:29 PM EDT Lev Olshvang wrote:
> >>  Hello list !
> >> 
> >>  A very technical question
> >>  I have Ubuntu 16.10 Virtual Box , auditd 2.7.8
> >>  I have audit=1 parameter in grub.cfg
> >>  I see that /proc/cmdline indeed sees it
> >> 
> >>  I see that auditd is started with PID 564
> >> 
> >>  root 312 2 0 23:12 ? 00:00:00 [kauditd]
> >>  root 564 1 0 23:12 ? 00:00:00 /sbin/auditd
> >> 
> >>  And I have 15 lost messages ???
> >>  auditctl -s
> >>  enabled 1
> >>  failure 1
> >>  pid 564
> >>  rate_limit 0
> >>  backlog_limit 16384
> >>  lost 15
> >>  backlog 0
> >>  backlog_wait_time 30
> >>  loginuid_immutable 0 unlocked
> >> 
> >>  auditctl -l
> >>  -a always,exit -F arch=b64 -S execve,execveat -F key=exec
> >> 
> >>  Do I understand correctly that auiditd is indeed started by systemd
> >> before
> >>  other services, except 2 that is listed in auditd.service dependencuies
> >> -
> >>  local-fs and some temp setup of systemd ?
> > 
> > Yes, it is started before most services. However. systemd-journal for some
> > reason feels obligated to enable auditing. And sometimes people put
> > audit=1 on the kernel command line. Either way, auditing is on way before
> > auditd starts. The audit logs have a 64 entry buffer by default. So, as
> > the system boots events pile up and eventually overflows the 64 entry
> > limit.
> > 
> > The fix is to add another boot command option audit_backlog_limit=8192 or
> > some other suitable number. The test to check for this is to boot your
> > system, login and run auditctl -s. If you have just booted and lost
> > events during boot, this should fix it.
> > 
> > -Steve
> 
> Hi Steve
> 
> Thank you for your answer.
> I added backlog parameter  as you advised, but it did not solve the problem
> 
> 
> cat /proc/cmdline
> BOOT_IMAGE=/vmlinuz-4.8.0-59-generic root=/dev/mapper/kubuntu--vg-root ro
> net.ifnames=0 biosdevname=0 audit=1 audit_backlog_limit=8192 debug splash
> auditctl -s
> enabled 1
> failure 1
> pid 672
> rate_limit 0
> backlog_limit 16384
> lost 16
> backlog 10
> backlog_wait_time 30
> loginuid_immutable 0 unlocked
> 
> Perhaps something else in configuration ?

You have a backlog of 10. That should normally be 0 unless the system is very 
busy. What do you have for the flush and freq settings in auditd.conf?

-Steve