Re: kauditd hold queue overflow in 4.11

[Laurent Bigonville <bigon@debian.org>]

Le 09/09/17 à 16:22, Steve Grubb a écrit :
> On Saturday, September 9, 2017 6:02:02 AM EDT Laurent Bigonville wrote:
>> Le 11/07/17 à 00:23, Paul Moore a écrit :
>>> On Mon, Jul 10, 2017 at 4:01 PM, Laurent Bigonville <bigon@debian.org>
> wrote:
>>>> Le 10/07/17 à 18:00, Paul Moore a écrit :
>>>>> On Mon, Jul 10, 2017 at 10:59 AM, Laurent Bigonville <bigon@debian.org>
>>>>>
>>>>> wrote:
>>>>>> Hi,
>>>>>>
>>>>>> With 4.11.6 (that has been uploaded in debian unstable) I get a lot of
>>>>>> messages in dmesg like
>>>>>>
>>>>>> [100052.120468] audit: audit_lost=66041 audit_rate_limit=0
>>>>>> audit_backlog_limit=8192
>>>>>> [100052.120470] audit: kauditd hold queue overflow
>>>>>>
>>>>>> And it also seems that the messages are not stored in auditd logs
>>>>>> anymore.
>>>>>>
>>>>>> https://git.kernel.org/linus/264d509637d95f9404e52ced5003ad352e0f6a26
>>>>>> seems
>>>>>> to be included in this release
>>>>>>
>>>>>> An idea?
>>>>> 7
>>>>> I'm going to assume that your backlog limit is set to a sane value for
>>>>> your system's configuration, so that leaves me with two commits that
>>>>> may be of interest:
>>>>>
>>>>> * 1df30f8264b8 ("audit: fix the RCU locking for the auditd_connection
>>>>> structure")
>>>>>
>>>>> This was a manual backport of a v4.12 patch to v4.11, looking now, I
>>>>> see it should be in +v4.11.5 so that probably isn't your problem ...
>>>>>
>>>>> * c81be52a3ac0 ("audit: fix a race condition with the auditd tracking
>>>>> code")
>>>>>
>>>>> This patch is relatively new and was just sent up to Linus during the
>>>>> next merge window; it's a race condition fix so reproducing it can be
>>>>> tricky, although it may be easily reproducible on your system at the
>>>>> moment (luck you!).  If you aren't in a position to apply the patch,
>>>>> the workaround is rather simple: restart auditd.
>>>>>
>>>>> If none of the above works, let me know, but I strongly suspect you're
>>>>> tripping over the race condition fixed in that last patch.
>>>> I didn't test the patch yet, but I restarted the auditd daemon 2 times
>>>> and
>>>> after that the queue has been flushed and I got all the message since
>>>> this
>>>> noon in the audit logs.
>>> That sounds right; I'm guessing the patch above should be a more permanent
>>> fix.
>> The patch should be applied in 4.13-rc7 right?
>>
>> It seems to fix the main issue (all the audit messages being logged in
>> dmesg) but I can still see from time to time the following message:
>>
>> [   14.747565] audit: audit_lost=59 audit_rate_limit=0
>> audit_backlog_limit=64 [   14.747566] audit: kauditd hold queue overflow
> That is a very low backlog_limit. Is this during boot?

Yes that's during boot (64 is the kernel's default)

In my audit.rules I have '-b 8192'

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