On Fri, Jun 10, 2016 at 04:42:51PM +0200, Lukas Slebodnik wrote:
On (10/06/16 12:07), Sumit Bose wrote:
>On Fri, Jun 10, 2016 at 11:09:49AM +0200, Lukas Slebodnik wrote:
>> On (10/06/16 09:54), Sumit Bose wrote:
>> >On Fri, Jun 10, 2016 at 09:26:38AM +0200, Lukas Slebodnik wrote:
>> >> ehlo,
>> >>
>> >> I took some time to find out why pam-srv-tests fails so often.
>> >>
https://fedorahosted.org/sssd/ticket/2994
>> >>
>> >> It is caused by slow execution of function sysdb_cache_password_ex.
>> >>
>> >> (Thu Jun 9 22:13:36:771048 2016) [sssd] [sysdb_cache_password_ex]
(0x0100): start.
>> >> (Thu Jun 9 22:13:36:771317 2016) [sssd] [sysdb_cache_password_ex]
(0x0100): Before s3crypt_gen_salt
>> >> (Thu Jun 9 22:13:36:771678 2016) [sssd] [sysdb_cache_password_ex]
(0x0100): Before s3crypt_sha512
>> >> (Thu Jun 9 22:13:38:022470 2016) [sssd] [sysdb_cache_password_ex]
(0x0100): Before sysdb_new_attrs
>> >> (Thu Jun 9 22:13:38:023115 2016) [sssd] [sysdb_cache_password_ex]
(0x0100): Before sysdb_attrs_add_string
>> >> (Thu Jun 9 22:13:38:023431 2016) [sssd] [sysdb_cache_password_ex]
(0x0100): Before sysdb_attrs_add_long
>> >> (Thu Jun 9 22:13:38:023829 2016) [sssd] [sysdb_cache_password_ex]
(0x0100): Before sysdb_attrs_add_long v2
>> >> (Thu Jun 9 22:13:38:024156 2016) [sssd] [sysdb_cache_password_ex]
(0x0100): Before sysdb_attrs_add_long v3
>> >> (Thu Jun 9 22:13:38:024482 2016) [sssd] [sysdb_cache_password_ex]
(0x0100): Before sysdb_attrs_add_uint32
>> >> (Thu Jun 9 22:13:38:024816 2016) [sssd] [sysdb_cache_password_ex]
(0x0100): Before sysdb_set_user_attr
>> >> (Thu Jun 9 22:13:38:035319 2016) [sssd] [sysdb_cache_password_ex]
(0x0100): return eok
>> >>
>> >> As you can see, the execution of function s3crypt_sha512
>> >> took almost two seconds.
>> >>
>> >> Is it caused by valgrind all low entropy?
>> >
>> >The random data for the salt is already collected in s3crypt_gen_salt().
>> >sha512_crypt_r() basically mingles and password and the salt and does
>> >hash operations.
>> >
>> >From a short inspection I can see nothing obvious which might cause such
>> >delay. Maybe nspr_nss_init() if we really have to init NSS at this
>> >point. The main operations in sha512_crypt_r() are heavily CPU bound, so
>> >maybe some scheduler decides that its time for a different process to get
>> >some CPU time?
>> >
>> >On the other hand can you give some details why the test fails because
>> >of this delay? It looks a bit like we depend on a specific execution
>> >time either in the test or the main code. If this is the case I think we
>> >would make the code more robust by removing this dependency.
>> >
>>
>> There are two possitive tests for pam authentication.
>> test_pam_cached_auth_success and
>> test_pam_cached_auth_success_combined_pw_with_cached_2fa
>>
>> The test case is:
>> * simulate authenticate in pam responder -> common_test_pam_cached_auth
>> * back-end should be contacted
>> * store cached password (here is slow function sysdb_cache_password_ex)
>> // we need to explicitely cache password because it is usually done in
>> // back-end
>> * simulate authenticate in pam responder -> common_test_pam_cached_auth
>> * back-end should *NOT* be contacted
>>
>> However, the value of cached_auth_timeout is set to 2 seconds in tests.
>> and therefore back-end is sometimes contected in second authentication.
>>
>> I tried to increase value of cached_auth_timeout 2 -> 4.
>> It helped a little bit but after this change
>> I can still see failures in pam-srv-tests but in differetn tests :-)
>>
>> [ FAILED ] test_pam_preauth_cert_nomatch
>> [ FAILED ] test_pam_preauth_cert_match
>> [ FAILED ] test_pam_preauth_cert_match_wrong_user
>> [ FAILED ] test_pam_preauth_cert_no_logon_name
>>
>> and it does not make sense to me
>> because it failes due to slow p11_child (30 seconds shoudl be enough
>> for p11_child)
>
>yes, 30s should be enough. Even in the cases where p11_child returns
>without a timeout it needs at least 10s to run trough an area of code
>where among other things NSS is initialized. Does the error only happen
>on RHEL6 or on other CI platforms as well?
>
hmm, I cannot reproduce anymore.
Attached is a patch which increases a cached_auth_timeout.
As Sumit already wrote: sha512_crypt_r() are heavily CPU bound
So it might happen that it will slow with valgrind.
I used just essential test-suit because I was
interested only in valgrind test which caused problems.
http://sssd-ci.duckdns.org/logs-test/job/0/88/summary.html
http://sssd-ci.duckdns.org/logs-test/job/0/89/summary.html
http://sssd-ci.duckdns.org/logs-test/job/0/90/summary.html
http://sssd-ci.duckdns.org/logs-test/job/0/91/summary.html
http://sssd-ci.duckdns.org/logs-test/job/0/92/summary.html
http://sssd-ci.duckdns.org/logs-test/job/0/93/summary.html
http://sssd-ci.duckdns.org/logs-test/job/0/94/summary.html
http://sssd-ci.duckdns.org/logs-test/job/0/95/summary.html
http://sssd-ci.duckdns.org/logs-test/job/0/96/summary.html
http://sssd-ci.duckdns.org/logs-test/job/0/97/summary.html
LS
From 7db9205d20244e810e4b497a7604696d956f790f Mon Sep 17 00:00:00
2001
From: Lukas Slebodnik <lslebodn(a)redhat.com>
Date: Fri, 10 Jun 2016 09:28:37 +0200
Subject: [PATCH] pam-srv-tests: Increase cached_auth_timeout
The execution sysdb_cache_password_ex can be slow
due to function s3crypt_sha512 and valgrind slowdown.
Therefore 2 seconds timeout can be reached
in possitive tests test_pam_cached_auth_success
and test_pam_cached_auth_success_combined_pw_with_cached_2fa
Resolves:
https://fedorahosted.org/sssd/ticket/2994
---
src/tests/cmocka/test_pam_srv.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
If this patch helped in your testing, then I say we should push it..