On (04/08/16 12:59), Lukas Slebodnik wrote: >On (04/08/16 11:38), Jakub Hrozek wrote: >>On Thu, Aug 04, 2016 at 11:26:41AM +0200, Jakub Hrozek wrote: >>> On Thu, Aug 04, 2016 at 11:19:36AM +0200, Lukas Slebodnik wrote: >>> > On (04/08/16 11:15), Jakub Hrozek wrote: >>> > >On Thu, Aug 04, 2016 at 08:45:00AM +0200, Lukas Slebodnik wrote: >>> > >> On (03/08/16 18:56), Lukas Slebodnik wrote: >>> > >> >On (29/07/16 16:41), Jakub Hrozek wrote: >>> > >> >>On Thu, Jul 28, 2016 at 01:56:50PM +0200, Jakub Hrozek wrote: >>> > >> >>> On Thu, Jul 28, 2016 at 01:33:32PM +0200, Lukas Slebodnik wrote: >>> > >> >>> > On (28/07/16 12:06), thierry bordaz wrote: >>> > >> >>> > >On 07/28/2016 09:39 AM, Jakub Hrozek wrote: >>> > >> >>> > >> On Wed, Jul 27, 2016 at 04:09:07PM +0200, thierry bordaz >>> > >> >>> > >> wrote: >>> > >> >>> > >> > >>> > >> >>> > >> > On 07/27/2016 03:36 PM, Jakub Hrozek wrote: >>> > >> >>> > >> > > On Wed, Jul 27, 2016 at 02:55:37PM +0200, thierry bordaz >>> > >> >>> > >> > > wrote: >>> > >> >>> > >> > > > On 07/27/2016 01:56 PM, Jakub Hrozek wrote: >>> > >> >>> > >> > > > > On Wed, Jul 27, 2016 at 01:03:59PM +0200, Jakub >>> > >> >>> > >> > > > > Hrozek wrote: >>> > >> >>> > >> > > > > > On Wed, Jul 27, 2016 at 12:22:46PM +0200, Lukas >>> > >> >>> > >> > > > > > Slebodnik wrote: >>> > >> >>> > >> > > > > > > On (27/07/16 12:08), Jakub Hrozek wrote: >>> > >> >>> > >> > > > > > > > On Wed, Jul 27, 2016 at 12:02:24PM +0200, Jakub >>> > >> >>> > >> > > > > > > > Hrozek wrote: >>> > >> >>> > >> > > > > > > > > On Wed, Jul 27, 2016 at 11:54:16AM +0200, >>> > >> >>> > >> > > > > > > > > Lukas Slebodnik wrote: >>> > >> >>> > >> > > > > > > > > > ehlo, >>> > >> >>> > >> > > > > > > > > > >>> > >> >>> > >> > > > > > > > > > attached patch fixes acces denied after >>> > >> >>> > >> > > > > > > > > > activating user in 389ds. >>> > >> >>> > >> > > > > > > > > > Jakub had some comments/ideas in ticket but >>> > >> >>> > >> > > > > > > > > > I think it's better to discuss >>> > >> >>> > >> > > > > > > > > > about virtual attributes and timestamp >>> > >> >>> > >> > > > > > > > > > cache on mailing list. >>> > >> >>> > >> > > > > > > > > Yes, so the comment I have is that while this >>> > >> >>> > >> > > > > > > > > works, it might break some >>> > >> >>> > >> > > > > > > > > strange LDAP servers. >>> > >> >>> > >> > > > > > > > > >>> > >> >>> > >> > > > > > > > > We use modifyTimestamp as a 'positive' >>> > >> >>> > >> > > > > > > > > indicator that the entry has not >>> > >> >>> > >> > > > > > > > > changed -- if the modifyTimestamp didn't >>> > >> >>> > >> > > > > > > > > change, we consider the cached >>> > >> >>> > >> > > > > > > > > entry the same as what is on the server and >>> > >> >>> > >> > > > > > > > > only bump the timestamp >>> > >> >>> > >> > > > > > > > > cache. If the timestamp is different, we do a >>> > >> >>> > >> > > > > > > > > deep-comparison of cached >>> > >> >>> > >> > > > > > > > > attribute values with what is on the LDAP >>> > >> >>> > >> > > > > > > > > server and write the sysdb >>> > >> >>> > >> > > > > > > > > cache entry only if the attributes differ. >>> > >> >>> > >> > > > > > > > > >>> > >> >>> > >> > > > > > > > > I was wondering if we can use the >>> > >> >>> > >> > > > > > > > > modifyTimestamp at all, then, because >>> > >> >>> > >> > > > > > > > > even if it's the same, we might want to check >>> > >> >>> > >> > > > > > > > > the attributes to see if >>> > >> >>> > >> > > > > > > > > some of the values are different because some >>> > >> >>> > >> > > > > > > > > of the attributes might be >>> > >> >>> > >> > > > > > > > > this operational/virtual attribute.. >>> > >> >>> > >> > > > > > > > Sorry, sent too soon. >>> > >> >>> > >> > > > > > > > >>> > >> >>> > >> > > > > > > > I think the questions are -- 1) can we >>> > >> >>> > >> > > > > > > > enumerate the virtual attributes? >>> > >> >>> > >> > > > > > > That might be a question for 389-ds developers. >>> > >> >>> > >> > > > > > > But it's very likely it will be different on >>> > >> >>> > >> > > > > > > other LDAP servers. >>> > >> >>> > >> > > > > > > >>> > >> >>> > >> > > > > > > > 2) Would different LDAP servers have different >>> > >> >>> > >> > > > > > > > virtual attributes. >>> > >> >>> > >> > > > > > > > >>> > >> >>> > >> > > > > > > > For 2) maybe a possible solution might be to >>> > >> >>> > >> > > > > > > > set a non-existing >>> > >> >>> > >> > > > > > > > modifyTimestamp attribute value, but I would >>> > >> >>> > >> > > > > > > > consider that only a >>> > >> >>> > >> > > > > > > > kludge, we shouldn't break existing setups.. >>> > >> >>> > >> > > > > > > I am not satisfied with this POC solution either. >>> > >> >>> > >> > > > > > > >>> > >> >>> > >> > > > > > > So should we remove usage of modifyTimestamp for >>> > >> >>> > >> > > > > > > detecting changes? >>> > >> >>> > >> > > > > > I would prefer to ask the DS developers before >>> > >> >>> > >> > > > > > removing it completely. >>> > >> >>> > >> > > > > > >>> > >> >>> > >> > > > > > At least for large groups it might take a long time >>> > >> >>> > >> > > > > > to compare all attribute >>> > >> >>> > >> > > > > > values and IIRC we don't depend on any virtual >>> > >> >>> > >> > > > > > attributes for groups. Maybe >>> > >> >>> > >> > > > > > we could parametrize that part of the code and >>> > >> >>> > >> > > > > > enable the fast way with >>> > >> >>> > >> > > > > > modifyTimestamps for 'known' server types, that is >>> > >> >>> > >> > > > > > for setups with AD and >>> > >> >>> > >> > > > > > IPA providers. >>> > >> >>> > >> > > > > > >>> > >> >>> > >> > > > > > For users, there is typically not as many >>> > >> >>> > >> > > > > > attributes so we should be >>> > >> >>> > >> > > > > > fine deep-comparing all attributes. >>> > >> >>> > >> > > > > I'm adding Thierry (so please reply-to-all to keep >>> > >> >>> > >> > > > > him in the thread). >>> > >> >>> > >> > > > > >>> > >> >>> > >> > > > > Thierry, in the latest sssd version we tried to add a >>> > >> >>> > >> > > > > performance >>> > >> >>> > >> > > > > improvement related to how we store SSSD entries in >>> > >> >>> > >> > > > > the cache. The short >>> > >> >>> > >> > > > > version is that we store the modifyTimestamp >>> > >> >>> > >> > > > > attribute in the cache and >>> > >> >>> > >> > > > > when we fetch an entry, we compare the entry >>> > >> >>> > >> > > > > modifyTimestamp with what >>> > >> >>> > >> > > > > is on the server. When the two are the same, we say >>> > >> >>> > >> > > > > that the entry did >>> > >> >>> > >> > > > > not change and don't update the cache. >>> > >> >>> > >> > > > > >>> > >> >>> > >> > > > > This works fine for most attributes, but not for >>> > >> >>> > >> > > > > attributes like >>> > >> >>> > >> > > > > nsAccountLock which do not change modifyTimestamp >>> > >> >>> > >> > > > > when they are >>> > >> >>> > >> > > > > modified. So when an entry was already cached but >>> > >> >>> > >> > > > > then nsAccountLock >>> > >> >>> > >> > > > > changed, we treated the entry as the same and never >>> > >> >>> > >> > > > > read the new >>> > >> >>> > >> > > > > nsAccountLock value. >>> > >> >>> > >> > > > > >>> > >> >>> > >> > > > > To fix this, I think we have several options: >>> > >> >>> > >> > > > > 1) special-case the nsAccountLock. This seems >>> > >> >>> > >> > > > > a bit dangerous, >>> > >> >>> > >> > > > > because I'm not sure we can say that some >>> > >> >>> > >> > > > > other attribute we are >>> > >> >>> > >> > > > > interested in behaves the same as >>> > >> >>> > >> > > > > nsAccountLock. >>> > >> >>> > >> > > > > 2) drop the modifyTimestamp optimization >>> > >> >>> > >> > > > > completely. Then we fall >>> > >> >>> > >> > > > > back to comparing the attribute values, which >>> > >> >>> > >> > > > > might work, but for >>> > >> >>> > >> > > > > huge objects like groups with thousands of >>> > >> >>> > >> > > > > members, this might be >>> > >> >>> > >> > > > > too expensive. >>> > >> >>> > >> > > > > 3) only use the modifyTimestamp optimization >>> > >> >>> > >> > > > > for cases where we know >>> > >> >>> > >> > > > > we don't read any virtual attributes. >>> > >> >>> > >> > > > > >>> > >> >>> > >> > > > > And my question is -- can we, in general, know if the >>> > >> >>> > >> > > > > modifyTimestamp >>> > >> >>> > >> > > > > way of detecting changes is realiable for all LDAP >>> > >> >>> > >> > > > > servers? Or do you >>> > >> >>> > >> > > > > think it should only be used for cases where we know >>> > >> >>> > >> > > > > we are not >>> > >> >>> > >> > > > > interested in any virtual attributes (that would >>> > >> >>> > >> > > > > mostly be storing >>> > >> >>> > >> > > > > groups from servers where we know exactly what is on >>> > >> >>> > >> > > > > the server side, >>> > >> >>> > >> > > > > like IPA or AD). >>> > >> >>> > >> > > > Hello, >>> > >> >>> > >> > > > >>> > >> >>> > >> > > > Relying on modifytimestamp looks a good idea. Any >>> > >> >>> > >> > > > MOD/MODRDN will update it, >>> > >> >>> > >> > > > except I think it is unchanged when updating some >>> > >> >>> > >> > > > password policy >>> > >> >>> > >> > > > attributes. >>> > >> >>> > >> > > > >>> > >> >>> > >> > > > Regarding virtual attribute, the only one I know in IPA >>> > >> >>> > >> > > > is nsaccountlock. >>> > >> >>> > >> > > > nsaccountlock is an operational attribute (you need to >>> > >> >>> > >> > > > request it to see it) >>> > >> >>> > >> > > > and is also a virtual attribute BUT only for 'staged' >>> > >> >>> > >> > > > and 'deleted' users. >>> > >> >>> > >> > > > It is a stored attribute for regular users and we >>> > >> >>> > >> > > > should update >>> > >> >>> > >> > > > modifytimestamp when it is set. >>> > >> >>> > >> > > > >>> > >> >>> > >> > > > thanks >>> > >> >>> > >> > > > thierry >>> > >> >>> > >> > > OK, in that case it seems like we can special-case it. >>> > >> >>> > >> > > But do you know >>> > >> >>> > >> > > about any other attributes in any other LDAP servers? >>> > >> >>> > >> > Any LDAP server following standard should provide >>> > >> >>> > >> > modifytimestamp that >>> > >> >>> > >> > reflect the last update of the entry. Now virtual attribute >>> > >> >>> > >> > values may be >>> > >> >>> > >> > "attached" to the entry and its value change without >>> > >> >>> > >> > modification of >>> > >> >>> > >> > modifytimestamp. >>> > >> >>> > >> > For 389-ds and IPA it is fine as virtual value of >>> > >> >>> > >> > nsaccountlock is changed >>> > >> >>> > >> > only when the DN change. >>> > >> >>> > >> > For others LDAP servers I suppose it exists the same >>> > >> >>> > >> > ability to define >>> > >> >>> > >> > service providers that return virtual attribute values. The >>> > >> >>> > >> > difficulty is >>> > >> >>> > >> > that the schema may not give any hint if the retrieved >>> > >> >>> > >> > attributes values >>> > >> >>> > >> > were stored or computed and consequently trust >>> > >> >>> > >> > modifytimestamp to know if >>> > >> >>> > >> > the values changed or not. >>> > >> >>> > >> > For example in ODSEE, memberof is a virtual attribute. >>> > >> >>> > >> Thank you, for the explanation Thierry. >>> > >> >>> > >> >>> > >> >>> > >> Then to be on the safe side I propose: >>> > >> >>> > >> 1) We add an (probably undocumented?) flag that says >>> > >> >>> > >> whether to use >>> > >> >>> > >> modifyTimestamp to detect entry changes or not >>> > >> >>> > >> 2) for the generic LDAP provider we always really >>> > >> >>> > >> compare the >>> > >> >>> > >> attribute values, in other words the option would be >>> > >> >>> > >> set to >>> > >> >>> > >> false. If there is anyone with performance issues >>> > >> >>> > >> with a generic >>> > >> >>> > >> setup, we tell them to flip the option. >>> > >> >>> > >> 3) For the IPA and AD providers, we set this option to >>> > >> >>> > >> true and use >>> > >> >>> > >> the modifyTimestamp value to detect changes >>> > >> >>> > >> 4) We special case nsAccountLock >>> > >> >>> > >> >>> > >> >>> > >> Lukas, do you agree? >>> > >> >>> > >Hi Jakub, >>> > >> >>> > > >>> > >> >>> > >digging further into the server, it appears that a DS plugin >>> > >> >>> > >'acctpolicy' >>> > >> >>> > >updates an entry without changing the mofidytimestamp. >>> > >> >>> > >The updated attribute is 'lastlogintime' (by default) but i >>> > >> >>> > >think can be any >>> > >> >>> > >attribute configured in the entry account policy. >>> > >> >>> > >I need to do further tests to confirm this. >>> > >> >>> > > >>> > >> >>> > >>> > >> >>> > IMHO, the problems with nsAccountLock just revealed the fact that >>> > >> >>> > it might happen that the attribute modifyTimestamp/whenChanged >>> > >> >>> > needn't be >>> > >> >>> > a reliable way how to determine change in entry for any LDAP >>> > >> >>> > Server. >>> > >> >>> > >>> > >> >>> > We improved the performance but there might be other corner >>> > >> >>> > cases with >>> > >> >>> > other LDAP servers. >>> > >> >>> > >>> > >> >>> > Jakub proosed in 2) that we should always really compare the the >>> > >> >>> > attibutes >>> > >> >>> > from sssd cache and from LDAP search. But it would mean that we >>> > >> >>> > would not >>> > >> >>> > improve a performance for generic LDAP providers. >>> > >> >>> >>> > >> >>> We would still avoid the cache writes, "only" after comparing the >>> > >> >>> attribute values. So essentially by using the modifyTimestamp we >>> > >> >>> save a >>> > >> >>> single LDB base search and a number of attribute-value comparisons, >>> > >> >>> depending on how large the object is. >>> > >> >>> >>> > >> >>> > >>> > >> >>> > We cannot generally detect virtual attributes for any LDAP >>> > >> >>> > server. >>> > >> >>> > What about adding an option where user could list virtual >>> > >> >>> > attributes. >>> > >> >>> > It would be a kind of proposed solution 4) but it would not be a >>> > >> >>> > special case for nsAccountLock but for more attributes which >>> > >> >>> > could be changed >>> > >> >>> > in configuration. >>> > >> >>> >>> > >> >>> OK, so your proposal is to keep the more aggressive cache >>> > >> >>> optimization? >>> > >> >>> I think I'm mostly afraid about the more exotic LDAP servers, like >>> > >> >>> IBM >>> > >> >>> Tivoli or Novell eDirectory which I already know from experience >>> > >> >>> don't >>> > >> >>> follow the established standards closely. I guess I'm fine with >>> > >> >>> that, we >>> > >> >>> can always flip the default back. Worst case for people who start >>> > >> >>> using >>> > >> >>> 1.14, the admin can always define modifyTimestamp to some >>> > >> >>> non-existing >>> > >> >>> attribute and force the attribute value comparison check. >>> > >> >>> >>> > >> >>> Yes, we can make the list configurable. We also need to be >>> > >> >>> very careful about printing the reason for (not) updating the >>> > >> >>> cache to >>> > >> >>> the admin (#3060). >>> > >> >> >>> > >> >>OK, so after some discussion with Simo on IRC, there is a different >>> > >> >>proposal - let responder control the optimization level, so that PAM >>> > >> >>responder would always trigger a full cache write, or at least >>> > >> >>deep-compare the attributes and NSS responder would rely on >>> > >> >>modifyTimestamp. >>> > >> >> >>> > >> >>But that's a larger fix, so for short-term fix I propose to only use >>> > >> >>modifyTimestamp for group objects and always compare attributes for >>> > >> >>users. Then later, as another patch we can let the responder send a >>> > >> >>flag >>> > >> >>to control the optimization (would probably be done as a flag for a >>> > >> >>sysdb transaction). >>> > >> >> >>> > >> >>If you agree, I would file a ticket for the second part and you can >>> > >> >>instead write a patch to disable modifyTimestamp checks for users. >>> > >> > >>> > >> >As you wish. >>> > >> >The updated patch is attached. >>> > >> > >>> > >> >LS >>> > >> >>> > >> >From ae01ffdbbc74c5b43c2b644f8847d856cd2bf997 Mon Sep 17 00:00:00 2001 >>> > >> >From: Lukas Slebodnik <lsleb...@redhat.com> >>> > >> >Date: Wed, 3 Aug 2016 18:48:04 +0200 >>> > >> >Subject: [PATCH] SYSDB: Avoid optimisation with modifyTimestamp for >>> > >> >users >>> > >> > >>> > >> >The usage of modifyTimestamp needn't be a reliable way >>> > >> >for detecting of changes in user entry in LDAP. >>> > >> >The authorisation need to rely current data from LDAP >>> > >> >and therefore we will temporary disable optimisation with >>> > >> >modifyTimestamp and we will rather rely on deep comparison >>> > >> >of attributes. In he future, it might be changed and >>> > >> >responders might control the optimization level. >>> > >> > >>> > >> And now with version witout failures in unit test and without compiler >>> > >> warnings >>> > >> :-) >>> > >> >>> > >> LS >>> > > >>> > >Hi, >>> > > >>> > >this patch doesn't apply atop origin/master, do I need some patches >>> > >before this one? >>> > >>> > I looks like I created patch on top of your patch >>> > [SSSD] [PATCH] SYSDB: Fix setting dataExpireTimestamp if sysdb is >>> > supposed to >>> > set the current time >>> > >>> > If you want I can create on origin/master but you would need to rebase >>> > your >>> > patch. So it depends on wich patch will be pushed the first >>> >>> I don't mind waiting and testing the patches together. I take it you'll >>> review my patch, then? >> >>Hmm, this still doesn't work: >> >>jhrozek@hendrix devel/sssd (review %) » git reset --hard origin/master >>HEAD is now at 2a03170 Fixed some typos in man pages >>jhrozek@hendrix devel/sssd (review %) » git am >>0001-SYSDB-Fix-setting-dataExpireTimestamp-if-sysdb-is-su.patch >>Applying: SYSDB: Fix setting dataExpireTimestamp if sysdb is supposed to set >>the current time >>jhrozek@hendrix devel/sssd (review %) » git am >>0001-SYSDB-Avoid-optimisation-with-modifyTimestamp-for-us.patch >>Applying: SYSDB: Avoid optimisation with modifyTimestamp for users >>error: patch failed: src/db/sysdb_ops.c:2465 >>error: src/db/sysdb_ops.c: patch does not apply >>Patch failed at 0001 SYSDB: Avoid optimisation with modifyTimestamp for users >>The copy of the patch that failed is found in: >> /home/remote/jhrozek/devel/sssd/.git/rebase-apply/patch >>When you have resolved this problem, run "git am --continue". >>If you prefer to skip this patch, run "git am --skip" instead. >>To restore the original branch and stop patching, run "git am --abort". >Hmm, > >attached patch is createn on top of current master >2a03170b6990c37ac2f7376ea740613c47ef2573 > and does not apply anymore on current master
Updated patch is attached. LS
>From 86f5491443de60c3656da343e6e36e7e3d6a0a9f Mon Sep 17 00:00:00 2001 From: Lukas Slebodnik <lsleb...@redhat.com> Date: Wed, 3 Aug 2016 18:48:04 +0200 Subject: [PATCH] SYSDB: Avoid optimisation with modifyTimestamp for users The usage of modifyTimestamp needn't be a reliable way for detecting of changes in user entry in LDAP. The authorisation need to rely current data from LDAP and therefore we will temporary disable optimisation with modifyTimestamp and we will rather rely on deep comparison of attributes. In he future, it might be changed and responders might control the optimization level. Resolves: https://fedorahosted.org/sssd/ticket/3110 --- src/db/sysdb_ops.c | 19 ------------------- src/tests/cmocka/test_sysdb_ts_cache.c | 14 -------------- 2 files changed, 33 deletions(-) diff --git a/src/db/sysdb_ops.c b/src/db/sysdb_ops.c index 67006c155098b9fde00a01d424014852c383a325..44fb5b70e6d33fffbca5824f831a3229254ecb57 100644 --- a/src/db/sysdb_ops.c +++ b/src/db/sysdb_ops.c @@ -1101,16 +1101,6 @@ done: return ret; } -static errno_t sysdb_check_and_update_ts_usr(struct sss_domain_info *domain, - const char *grp_name, - struct sysdb_attrs *attrs, - uint64_t cache_timeout, - time_t now) -{ - return sysdb_check_and_update_ts_obj(domain, SYSDB_USER, grp_name, - attrs, cache_timeout, now); -} - static errno_t sysdb_check_and_update_ts_grp(struct sss_domain_info *domain, const char *grp_name, struct sysdb_attrs *attrs, @@ -2470,15 +2460,6 @@ int sysdb_store_user(struct sss_domain_info *domain, now = time(NULL); } - ret = sysdb_check_and_update_ts_usr(domain, name, attrs, - cache_timeout, now); - if (ret == EOK) { - DEBUG(SSSDBG_TRACE_LIBS, - "The user record of %s did not change, only updated " - "the timestamp cache\n", name); - return EOK; - } - tmp_ctx = talloc_new(NULL); if (!tmp_ctx) { return ENOMEM; diff --git a/src/tests/cmocka/test_sysdb_ts_cache.c b/src/tests/cmocka/test_sysdb_ts_cache.c index aa857e7e4823d2d8ba1e1a794b3e2474876e9ab0..e950f88631e4c78573bbb7290edfe94b5ced57cd 100644 --- a/src/tests/cmocka/test_sysdb_ts_cache.c +++ b/src/tests/cmocka/test_sysdb_ts_cache.c @@ -980,20 +980,6 @@ static void test_sysdb_user_update(void **state) assert_int_equal(cache_expire_sysdb, TEST_CACHE_TIMEOUT + TEST_NOW_2); assert_int_equal(cache_expire_ts, TEST_CACHE_TIMEOUT + TEST_NOW_2); - /* Update the same attrs and the same modifyTimestamp. - * Only the timestamp cache must be bumped */ - ret = sysdb_store_user(test_ctx->tctx->dom, TEST_USER_NAME, NULL, - TEST_USER_UID, TEST_USER_GID, TEST_USER_NAME, - "/home/"TEST_USER_NAME, "/bin/bash", NULL, - user_attrs, NULL, TEST_CACHE_TIMEOUT, - TEST_NOW_3); - assert_int_equal(ret, EOK); - - get_pw_timestamp_attrs(test_ctx, TEST_USER_NAME, - &cache_expire_sysdb, &cache_expire_ts); - assert_int_equal(cache_expire_sysdb, TEST_CACHE_TIMEOUT + TEST_NOW_2); - assert_int_equal(cache_expire_ts, TEST_CACHE_TIMEOUT + TEST_NOW_3); - /* Update with different modifyTimestamp but same attrs as previously * saved to the timestamp cache. We should detect the 'real' attributes * are the same and only bump the timestamp cache -- 2.9.2
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