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Re: Contribution: Active Directory Password Cache (ITS#5042)
by ando＠sys-net.it 07 Aug '07

07 Aug '07

ando(a)sys-net.it wrote: > At this point, it sounds like that your contribution could be > __entirely__ reworked into simply adding caching capabilities into the > current {SASL} password scheme (implemented in servers/slapd/sasl.c), > preserving the logics you're using right now. You'd probably need to > define your own "cachedUserPassword" attribute to temporarily store the > cached credentials, unless something like this: > > userPassword: {SASL}user > userPassword: {<hash>}<hashed password> > > allows the {SASL} module to fetch the next value of the userPassowrd and > treat it as the cached value. The rest would be adding some TTL mech, > configurable via back-config, and that should be it. > > Yet another option would be to allow per-entry caching, by defining a > new {CACHED-SASL} scheme. This way, one could fine-grain decide whose > credentials can be cached and whose can't, letting the two cases share > most of the code. I'd allow {SASL} to be cached as well, in case the > administrator just wants to allow all {SASL} auths to be cached. For this purpose, it might be necessary to change the API of password scheme handling, so that it gets passed a pointer to the entire entry, read-only locked, so that attributes like the "cachedPwd" and the "cachedPwdTimestamp" can be fetched and used. With respect to updating them, we might need to add some means to schedule internal modifications to be performed as soon as the entry lock is released. Thoughts? p. Ing. Pierangelo Masarati OpenLDAP Core Team SysNet s.r.l. via Dossi, 8 - 27100 Pavia - ITALIA http://www.sys-net.it --------------------------------------- Office: +39 02 23998309 Mobile: +39 333 4963172 Email: pierangelo.masarati(a)sys-net.it ---------------------------------------

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Re: Contribution: Active Directory Password Cache (ITS#5042)
by ando＠sys-net.it 07 Aug '07

07 Aug '07

s.hetze(a)linux-ag.de wrote: > Renaming the variables is no problem. What would you say extpwc stands > for? EXT ernal P ass W ord C ache? > I can imagine to call the module krb5pwc and head the README > "Kerberos V/Active Directory Password Cache" Right; but, this would limit yourself to Kerberos V; see my other posting about rather delegating auth to SASL. >> Well, that could be a parameter that is provided through the >> configuration (caching TTL, optional negative caching TTL, and so). It >> doesn't need to be stored in the entry, or in a subentry, since dynamic >> configuration would allow to modify it run-time anyway. >> > > If I understand it correct, you suggest to let the cached password > expire after some configurable time. To achieve this, I would need to > keep a timestamp when the password was cached. > Is there any other way than to add an attribute holding this timestamp? > ... > Actually, I could make this feature depend on the {ad|krb5}pw-cache-mode=any > and use the sambaPwdLastSet attribute. Right; I think a specific operational attribute would be better. p. Ing. Pierangelo Masarati OpenLDAP Core Team SysNet s.r.l. via Dossi, 8 - 27100 Pavia - ITALIA http://www.sys-net.it --------------------------------------- Office: +39 02 23998309 Mobile: +39 333 4963172 Email: pierangelo.masarati(a)sys-net.it ---------------------------------------

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Re: Contribution: Active Directory Password Cache (ITS#5042)
by s.hetze＠linux-ag.de 07 Aug '07

07 Aug '07

Hi Pierangelo, On Tue, Aug 07, 2007 at 11:41:58AM +0200, Pierangelo Masarati wrote: > s.hetze(a)linux-ag.de wrote: > > >>2) you could try to rework the overlay to avoid any specific reference > >>to Active Directory, since your cache should apply to any remote system > >>implementing Kerberos V. It could be abstracted even more, to act as a > >>replacement of saslauthd, by allowing it to auth via LDAP, pam and more, > >>not just Kerberos. > > > >Actually, the software was built and tested agains MIT and Heimdal > >Kerberos V in the first place, so there is no dependency on AD > >whatsoever. The reference to AD is more a marketing issue. I assume > >more users looking for an AD password cache than for an Kerberos V > >password cache. So I would perfer to keep it. > > I understand this, and I think it's just fine to advertise it like that, > but in the code I'd prefer to avoid, for example, naming all variables > after "ad" something. Perhaps s/adpwc/extpwc/ would be a little bit better? Renaming the variables is no problem. What would you say extpwc stands for? I can imagine to call the module krb5pwc and head the README "Kerberos V/Active Directory Password Cache" > > >>3) you should add a (configurable) TTL, so that the cache could > >>eventually be notified of an account lockout at the remote server's side. > > > >I tried to avoid introduction of new attributes for the module. Do you > >have any suggestions how this TTL should be stored? Adding pwdPolicy > >from ppolicy seems a bit like an overkill to me. > > Well, that could be a parameter that is provided through the > configuration (caching TTL, optional negative caching TTL, and so). It > doesn't need to be stored in the entry, or in a subentry, since dynamic > configuration would allow to modify it run-time anyway. > If I understand it correct, you suggest to let the cached password expire after some configurable time. To achieve this, I would need to keep a timestamp when the password was cached. Is there any other way than to add an attribute holding this timestamp? ... Actually, I could make this feature depend on the {ad|krb5}pw-cache-mode=any and use the sambaPwdLastSet attribute. > >>4) you should add support for dynamic configuration, so that the module > >>can fit into the new configuration paradigm for possible release with 2.4. > > > >I'll look into that. > > If you need help, please holler. However, I see that for such a simple > (from a configuration point of view) module, looking into smbk5pwd > should suffice. Thanx for your offer, and I agree to look into the existing overlays (again ;-) That's the fun with free software! Regards, Sebastian

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Re: Contribution: Active Directory Password Cache (ITS#5042)
by ando＠sys-net.it 07 Aug '07

07 Aug '07

s.hetze(a)linux-ag.de wrote: > I don't see the benefit of delegating the password cache mechanism to > saslauthd or a possible replacement. Wouldn't I have to implement each > possible password store anyway? > If I understand it correct, the {SASL} userPassword mechanism delegates > authentication to saslauthd. > saslauthd can easily authenticate against Kerberos and AD and it is > possible let it cache the password for its own authentication purposes. > If I want the sambaNTPassword attribute to be available (to be able to > run samba as a NT4 PDC independent of AD ) or if I want to have the > password additionally cached as MIT Kerberos credential, I would need > to implement both individually one way or another. > So why not going the short way and let the overlay module do this? The {SASL} userPassword delegates authentication to SASL; then, by configuring SASL to use saslauthd, SASL delegates authentication to saslauthd, but it can be delegated to anything else. I think the point is: you should isolate what your piece of software is originally contributing, and what it's "reinventing". The original contribution, as far as I understand, is the capability to cache athentication rather than always propagating it. This capability is not currently present in OpenLDAP. What is already present is the SASL, which is an abstraction layer for authentication; think of it as a superset of Kerberos, which is the only authentication method you're considering in your piece of software. At this point, it sounds like that your contribution could be __entirely__ reworked into simply adding caching capabilities into the current {SASL} password scheme (implemented in servers/slapd/sasl.c), preserving the logics you're using right now. You'd probably need to define your own "cachedUserPassword" attribute to temporarily store the cached credentials, unless something like this: userPassword: {SASL}user userPassword: {<hash>}<hashed password> allows the {SASL} module to fetch the next value of the userPassowrd and treat it as the cached value. The rest would be adding some TTL mech, configurable via back-config, and that should be it. Yet another option would be to allow per-entry caching, by defining a new {CACHED-SASL} scheme. This way, one could fine-grain decide whose credentials can be cached and whose can't, letting the two cases share most of the code. I'd allow {SASL} to be cached as well, in case the administrator just wants to allow all {SASL} auths to be cached. p. Ing. Pierangelo Masarati OpenLDAP Core Team SysNet s.r.l. via Dossi, 8 - 27100 Pavia - ITALIA http://www.sys-net.it --------------------------------------- Office: +39 02 23998309 Mobile: +39 333 4963172 Email: pierangelo.masarati(a)sys-net.it ---------------------------------------

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Re: Contribution: Active Directory Password Cache (ITS#5042)
by s.hetze＠linux-ag.de 07 Aug '07

07 Aug '07

Hi Kurt, On Mon, Aug 06, 2007 at 12:55:11PM -0700, Kurt Zeilenga wrote: > >2) you could try to rework the overlay to avoid any specific reference > >to Active Directory, since your cache should apply to any remote > >system > >implementing Kerberos V. It could be abstracted even more, to act > >as a > >replacement of saslauthd, by allowing it to auth via LDAP, pam and > >more, > >not just Kerberos. > > s/to act as a replacement/to defer external authentication to saslauthd > or the like/ > > In slapd(8), we deferred verification against external password > stores to saslauthd > via the {SASL} userPassword mechanism, thus avoiding needing to > implement > and support each possible external password store (such as a KDC). > This module > should likewise avoid supporting (some subset of) external passwords > stores. > saslauthd(8) can easily be extended (or replaced) to support additional > password stores as needed. As provided in Cyrus SASL today, it > supports both > LDAP and Kerberos as external password stores. > I don't see the benefit of delegating the password cache mechanism to saslauthd or a possible replacement. Wouldn't I have to implement each possible password store anyway? If I understand it correct, the {SASL} userPassword mechanism delegates authentication to saslauthd. saslauthd can easily authenticate against Kerberos and AD and it is possible let it cache the password for its own authentication purposes. If I want the sambaNTPassword attribute to be available (to be able to run samba as a NT4 PDC independent of AD ) or if I want to have the password additionally cached as MIT Kerberos credential, I would need to implement both individually one way or another. So why not going the short way and let the overlay module do this? Regards, Sebastian

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Re: Contribution: Active Directory Password Cache (ITS#5042)
by ando＠sys-net.it 07 Aug '07

07 Aug '07

s.hetze(a)linux-ag.de wrote: >> 2) you could try to rework the overlay to avoid any specific reference >> to Active Directory, since your cache should apply to any remote system >> implementing Kerberos V. It could be abstracted even more, to act as a >> replacement of saslauthd, by allowing it to auth via LDAP, pam and more, >> not just Kerberos. > > Actually, the software was built and tested agains MIT and Heimdal > Kerberos V in the first place, so there is no dependency on AD > whatsoever. The reference to AD is more a marketing issue. I assume > more users looking for an AD password cache than for an Kerberos V > password cache. So I would perfer to keep it. I understand this, and I think it's just fine to advertise it like that, but in the code I'd prefer to avoid, for example, naming all variables after "ad" something. Perhaps s/adpwc/extpwc/ would be a little bit better? >> 3) you should add a (configurable) TTL, so that the cache could >> eventually be notified of an account lockout at the remote server's side. > > I tried to avoid introduction of new attributes for the module. Do you > have any suggestions how this TTL should be stored? Adding pwdPolicy > from ppolicy seems a bit like an overkill to me. Well, that could be a parameter that is provided through the configuration (caching TTL, optional negative caching TTL, and so). It doesn't need to be stored in the entry, or in a subentry, since dynamic configuration would allow to modify it run-time anyway. >> 4) you should add support for dynamic configuration, so that the module >> can fit into the new configuration paradigm for possible release with 2.4. > > I'll look into that. If you need help, please holler. However, I see that for such a simple (from a configuration point of view) module, looking into smbk5pwd should suffice. >> 5) you should follow coding guidelines (indentation and so) as in most >> of the code. > > I did not find any guidelines other than "Adapt your style to match that > of the block, file, directory, or package that you are working in." > Can you point me to a more detailed explanation of the required > indentation? There isn't actually, but looking into any "recent" piece of code would suffice; things like: use tabs for indent, leave spaces in brackets and so... not a big deal, though. Cheers, p. Ing. Pierangelo Masarati OpenLDAP Core Team SysNet s.r.l. via Dossi, 8 - 27100 Pavia - ITALIA http://www.sys-net.it --------------------------------------- Office: +39 02 23998309 Mobile: +39 333 4963172 Email: pierangelo.masarati(a)sys-net.it ---------------------------------------

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Re: Contribution: Active Directory Password Cache (ITS#5042)
by s.hetze＠linux-ag.de 07 Aug '07

07 Aug '07

Hi Pierangelo, thanx for your comments. On Mon, Aug 06, 2007 at 09:32:27PM +0200, Pierangelo Masarati wrote: > Sebastian, > > Thanks for the contribution. > > I have a few comments (also gathered from others): > > 1) you should provide patches against HEAD code; there has been some > limited changes in the API related to overlay initialization and so. No problem, I will look into that shortly. > > 2) you could try to rework the overlay to avoid any specific reference > to Active Directory, since your cache should apply to any remote system > implementing Kerberos V. It could be abstracted even more, to act as a > replacement of saslauthd, by allowing it to auth via LDAP, pam and more, > not just Kerberos. Actually, the software was built and tested agains MIT and Heimdal Kerberos V in the first place, so there is no dependency on AD whatsoever. The reference to AD is more a marketing issue. I assume more users looking for an AD password cache than for an Kerberos V password cache. So I would perfer to keep it. > > 3) you should add a (configurable) TTL, so that the cache could > eventually be notified of an account lockout at the remote server's side. I tried to avoid introduction of new attributes for the module. Do you have any suggestions how this TTL should be stored? Adding pwdPolicy from ppolicy seems a bit like an overkill to me. > > 4) you should add support for dynamic configuration, so that the module > can fit into the new configuration paradigm for possible release with 2.4. I'll look into that. > > 5) you should follow coding guidelines (indentation and so) as in most > of the code. I did not find any guidelines other than "Adapt your style to match that of the block, file, directory, or package that you are working in." Can you point me to a more detailed explanation of the required indentation? Regards, Sebastian

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(ITS#5077) syncrepl.add_cmp() infinite loop on swapped values
by donn＠u.washington.edu 06 Aug '07

06 Aug '07

Full_Name: Donn Cave Version: 2.4.4 OS: Red Hat Linux URL: ftp://ftp.openldap.org/incoming/ Submission from: (NULL) (128.95.135.150) In "while" loop at 2656, I find old->a_vals are like [..., a, b, ...] and new->a_vals are like [..., b, a, ...]. Matches are found at old [i] == new [k = j+1] and old [k = i+1] == new [j], but this just shows that neither an add nor a delete is called for, and the loop end is reached without having incremented i or j. Actual attribute values I'm looking at right now in the debugger are eduPersonAffiliation: old [ member, alum, employee, faculty ], new [ member, alum, faculty, employee ]. I built the replica from a slapcat dump on the idle master, started the slapd syncrepl client and applied a lot of normal modifications to the master, until it hit the infinite loop. It has been a recurrent problem.

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Re: Contribution: Active Directory Password Cache (ITS#5042)
by kurt＠OpenLDAP.org 06 Aug '07

06 Aug '07

On Aug 6, 2007, at 7:31 PM, ando(a)sys-net.it wrote: > Sebastian, > > Thanks for the contribution. > > I have a few comments (also gathered from others): > > 1) you should provide patches against HEAD code; there has been some > limited changes in the API related to overlay initialization and so. > > 2) you could try to rework the overlay to avoid any specific reference > to Active Directory, since your cache should apply to any remote > system > implementing Kerberos V. It could be abstracted even more, to act > as a > replacement of saslauthd, by allowing it to auth via LDAP, pam and > more, > not just Kerberos. s/to act as a replacement/to defer external authentication to saslauthd or the like/ In slapd(8), we deferred verification against external password stores to saslauthd via the {SASL} userPassword mechanism, thus avoiding needing to implement and support each possible external password store (such as a KDC). This module should likewise avoid supporting (some subset of) external passwords stores. saslauthd(8) can easily be extended (or replaced) to support additional password stores as needed. As provided in Cyrus SASL today, it supports both LDAP and Kerberos as external password stores. > > 3) you should add a (configurable) TTL, so that the cache could > eventually be notified of an account lockout at the remote server's > side. > > 4) you should add support for dynamic configuration, so that the > module > can fit into the new configuration paradigm for possible release > with 2.4. > > 5) you should follow coding guidelines (indentation and so) as in most > of the code. > > p.

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Re: Contribution: Active Directory Password Cache (ITS#5042)
by ando＠sys-net.it 06 Aug '07

06 Aug '07

Sebastian, Thanks for the contribution. I have a few comments (also gathered from others): 1) you should provide patches against HEAD code; there has been some limited changes in the API related to overlay initialization and so. 2) you could try to rework the overlay to avoid any specific reference to Active Directory, since your cache should apply to any remote system implementing Kerberos V. It could be abstracted even more, to act as a replacement of saslauthd, by allowing it to auth via LDAP, pam and more, not just Kerberos. 3) you should add a (configurable) TTL, so that the cache could eventually be notified of an account lockout at the remote server's side. 4) you should add support for dynamic configuration, so that the module can fit into the new configuration paradigm for possible release with 2.4. 5) you should follow coding guidelines (indentation and so) as in most of the code. p. Ing. Pierangelo Masarati OpenLDAP Core Team SysNet s.r.l. via Dossi, 8 - 27100 Pavia - ITALIA http://www.sys-net.it --------------------------------------- Office: +39 02 23998309 Mobile: +39 333 4963172 Email: pierangelo.masarati(a)sys-net.it ---------------------------------------

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