On (28/07/16 16:37), thierry bordaz wrote: >On 07/28/2016 12:58 PM, Lukas Slebodnik wrote: >> On (28/07/16 12:44), thierry bordaz wrote: >> > >> > On 07/28/2016 11:17 AM, Lukas Slebodnik wrote: >> > > On (28/07/16 10:24), 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 >> > > > I am not sure I understand why nsAccountLock is a special case ? >> > > > In IPA/389: >> > > > >> > > > * Stage user, it is always 'nsaccountlock: True' >> > > > When stage entry is created or updated, 'modifytimestamp' is also >> > > > updated. So you can rely on modifytimestamp to detect a change in a >> > > > stage user. >> > > > There is no way to update nsaccountlock for a stage entry >> > > > * Deleted user. Idem Stage user >> > > We haven't tested stage users yet. I ran just sssd related regression >> > > tests. >> > > >> > > > * Regular user. 'nsaccountlock' is *not* a virtual attribute, so if it >> > > > is enable/disable you can rely on modifytimestamp to detect a >> > > > change >> > > > of 'nsaccountlock' for a regular user. >> > > > Also any change on regular user will update 'modifytimestamp' so >> > > > you >> > > > can rely on it to detect a change. >> > > > >> > > My experience with ns-inactivate.pl and ns-activate.pl is different. >> > > modifytimestamp is not changed even though nsaccountlock was changed. >> > > >> > > It was a plain 389-ds with id_provider ldap in sssd >> > > >> > > LS >> > Hi Lukas, >> > >> > >> > It may have change recently because I can not reproduce. What versions are >> > you running ? >> > >> > # >> > #initial entry >> > # >> > ldapsearch -LLL -o ldif-wrap=no -D "cn=directory manager" -w xxx -b >> > "cn=accounts, <suffix>" 'uid=user0' nsaccountlock modifytimestamp >> > createtimestamp >> > dn: uid=user0,cn=users,cn=accounts,<suffix> >> > modifytimestamp: *20160728103441Z* >> > createtimestamp: 20160726160436Z >> > >> > # >> > # Inactivate: modifytimestamp changed >> > # >> > /usr/sbin/ns-inactivate.pl -Z <instance> -D "cn=directory manager" >> > -w xxx -I uid=user0,cn=users,cn=accounts,<suffix> >> > uid=user0,cn=users,cn=accounts,<suffix> inactivated. >> > >> > ldapsearch -LLL -o ldif-wrap=no -D "cn=directory manager" -w xxx -b >> > "cn=accounts, <suffix>" 'uid=user0' nsaccountlock modifytimestamp >> > createtimestamp >> > dn: uid=user0,cn=users,cn=accounts,<suffix> >> > nsaccountlock: true >> > modifytimestamp: *20160728103642Z* >> > createtimestamp: 20160726160436Z >> > >> > # >> > # activate: modifytimestamp changed >> > # >> > /usr/sbin/ns-activate.pl -Z <instance> -D "cn=directory manager" -w >> > xxx -I uid=user0,cn=users,cn=accounts,<suffix> >> > uid=user0,cn=users,cn=accounts,<suffix> activated. >> > >> > ldapsearch -LLL -o ldif-wrap=no -D "cn=directory manager" -w xxx -b >> > "cn=accounts, <suffix>" 'uid=user0' nsaccountlock modifytimestamp >> > createtimestamp >> > dn: uid=user0,cn=users,cn=accounts,<suffix> >> > modifytimestamp: *20160728103711Z* >> > createtimestamp: 20160726160436Z >> > >> rhel7.3 >> 389-ds-base-1.3.5.10-5.el7.x86_64 >> >> But I didn't test directly with user but indirectly >> >> *Add Managed role >> dn: cn=managed,ou=people,dc=example,dc=com >> objectclass: top >> objectclass: LdapSubEntry >> objectclass: nsRoleDefinition >> objectclass: nsSimpleRoleDefinition >> objectclass: nsManagedRoleDefinition >> cn: Managed >> >> *Authenticate with lockuser >> >> *Add user to managed role >> dn: uid=lockuser,ou=people,dc=example,dc=com >> changetype: modify >> add: nsRoleDN >> nsRoleDN: cn=managed,ou=people,dc=example,dc=com >> >> ns-inactivate.pl -D cn=Manager,dc=example,dc=com" -E -p 389 \ >> -h $SERVER -I cn=managed,ou=people,dc=example,dc=com >> >> *Authenticate with lockuser >> >> ns-activate.pl -D cn=Manager,dc=example,dc=com" -E -p 389 \ >> -h $SERVER -I cn=managed,ou=people,dc=example,dc=com >> >> *Authenticate with lockuser >> >> Should I test with rhel7.2 or is it an expected behaviour ? >> >> LS > >That is correct and this is the expected behavior. >Using ns-inactivate.pl with a role, it inactivates all the entries in that >role adding nsaccountlock virtual attibute. >You are right, update (add of nsaccountlock) of regular user can be done >without update of its modifytimestamp. >
Thank you very much for confirmation and for info that plugin is not used on IPA. So we needn't special case nsaccountlock for IPA. We had a discussion on sssd devel meeting. And we agreed that we will do some performace measurements. And if there will be significant difference then we will check modifytimestamp only with IPA and AD. and it will be disabled by default with generic LDAP. LS _______________________________________________ sssd-devel mailing list sssd-devel@lists.fedorahosted.org https://lists.fedorahosted.org/admin/lists/sssd-devel@lists.fedorahosted.org
