Thread

Re: [v9.1] sepgsql - userspace access vector cache

Kohei KaiGai <kaigai@kaigai.gr.jp> — 2011-07-14T19:46:26Z

Sorry, the syscache part was mixed to contrib/sepgsql part
in my previous post.
Please see the attached revision.

Although its functionality is enough simple (it just reduces
number of system-call invocation), its performance
improvement is obvious.
So, I hope someone to volunteer to review these patches.

Thanks,

2011/7/11 Kohei KaiGai <kaigai@kaigai.gr.jp>:
> I rebased the userspace access vector cache patch to the latest tree.
>
> I'll describe the background of this patch because this thread has not been
> active more than a week.
> The sepgsql asks in-kernel selinux when it needs to make its access control
> decison, so it always causes system call invocations.
> However, access control decision of selinux for a particular pair of security
> label is consistent as long as its security policy is not reloaded.
> Thus, it is a good idea to cache access control decisions recently used in
> userspace.
> In addition, current GetSecurityLabel() always open pg_seclabel catalog and
> scan to fetch security label of database objects, although it is a situation we
> can utilize syscache mechanism.
>
> The "uavc-syscache" patch adds a new SECLABELOID syscache.
> It also redefine pg_seclabel.provide as Name, instead of Text, according to
> the suggestion from Tom.
> (To avoid collation conscious datatype)
>
> The "uavc-selinux-cache" patch adds cache mechanism of contrib/sepgsql.
> Its internal api to communicate with selinux (sepgsql_check_perms) was
> replaced by newer sepgsql_avc_check_perms that checks cached access
> control decision at first, prior to system call invocations.
>
> The result of performance improvement is obvious.
>
> * Test 2. time to run 50,000 of SELECT from empty tables
>  selinux | SECLABELOID syscache
>  avc   |   without |   with
> ---------+-----------------------
>  without | 185.59[s] | 178.38[s]
> ---------+-----------------------
>  with    |  23.58[s] |  21.79[s]
> ---------+-----------------------
>
> I strongly hope this patch (and security label support on shared objects) to
> get unstreamed  in this commit-fest, because it will perform as a basis of
> other upcoming features.
> Please volunteer the reviewing!
>
> Thanks,
>
> 2011/7/2 Kohei KaiGai <kaigai@kaigai.gr.jp>:
>> The attached patch re-defines pg_seclabel.provider as NameData, instead of Text,
>> and revert changes of catcache.c about collations; to keep consistency with the
>> security label support on shared objects.
>> All the format changes are hidden by (Get|Set)SecurityLabel(), so no
>> need to change
>> on the patch to contrib/sepgsql.
>>
>> Thanks,
>>
>> 2011/6/13 Kohei KaiGai <kaigai@kaigai.gr.jp>:
>>> 2011/6/13 Robert Haas <robertmhaas@gmail.com>:
>>>> On Mon, Jun 13, 2011 at 7:51 AM, Kohei KaiGai <kaigai@kaigai.gr.jp> wrote:
>>>>> For syscache, length of a typical security label in selinux is
>>>>> less than 64 bytes. If we assume an entry consume 128bytes
>>>>> including Oid pairs or pointers, its consumption is 128KBytes
>>>>> per 1,000 of tables or others.
>>>>> (Do we have a way to confirm syscache status?)
>>>>
>>>> I was thinking you might start a new session, SELECT pg_backendd_pid()
>>>> to get the PID, use top/ps to get its memory usage; then do a bunch of
>>>> stuff and see how much it's grown.  The difference between how much it
>>>> grows with and without the patch is the amount of additional memory
>>>> the patch consumes.
>>>>
>>> I checked memory consumption of the backend with / without
>>> patches. Because sepgsql_restorecon() tries to reset security
>>> label of all the schemas, relations, columns and procedures,
>>> an execution of this function is suitable to emphasize differences
>>> between two cases in maximum.
>>>
>>> The results shows us about 3MB of additional consumption
>>> in VmRSS, even if it caches all the security label of the objects
>>> being created in the default (3331 entries).
>>>
>>> * without patches before/after sepgsql_restorecon()
>>>
>>> VmPeak:   150812 kB -> 170864 kB
>>> VmSize:   150804 kB -> 154712 kB
>>> VmLck:         0 kB -> 0kB
>>> VmHWM:      3800 kB -> 22248 kB
>>> VmRSS:      3800 kB -> 10620 kB
>>> VmData:     1940 kB ->  5820 kB
>>> VmStk:       196 kB -> 196 kB
>>> VmExe:      5324 kB -> 5324 kB
>>> VmLib:      2468 kB -> 2468 kB
>>> VmPTE:       108 kB -> 120 kB
>>> VmSwap:        0 kB -> 0kB
>>>
>>> * with patches before/after sepgsql_restorecon()
>>> VmPeak:   150816 kB -> 175092 kB
>>> VmSize:   150808 kB -> 158804 kB
>>> VmLck:         0 kB -> 0 kB
>>> VmHWM:      3868 kB -> 25956 kB
>>> VmRSS:      3868 kB -> 13736 kB
>>> VmData:     1944 kB -> 9912 kB
>>> VmStk:       192 kB -> 192 kB
>>> VmExe:      5324 kB -> 5324 kB
>>> VmLib:      2472 kB -> 2472 kB
>>> VmPTE:       100 kB -> 124 kB
>>> VmSwap:        0 kB -> 0 kB
>>>
>>> Thanks,
>>> --
>>> KaiGai Kohei <kaigai@kaigai.gr.jp>
>>>
>>
>>
>>
>> --
>> KaiGai Kohei <kaigai@kaigai.gr.jp>
>>
>
>
>
> --
> KaiGai Kohei <kaigai@kaigai.gr.jp>
>



-- 
KaiGai Kohei <kaigai@kaigai.gr.jp>