Re: LDAP where DN does not include UID attribute

Following a discussion on the pgsql-admin list <
http://archives.postgresql.org/pgsql-admin/2009-09/msg00075.php>, I have
created a patch to (optionally) allow PostgreSQL to do a LDAP search to
determine the user's DN (as is done in Apache, MediaWiki, Bugzilla, et al.)
instead of building the DN from a prefix and suffix.
This is necessary for schemas where the login attribute is not in the DN,
such as is described here <
http://www.ldapman.org/articles/intro_to_ldap.html#individual> (look for
"name-based"). This patch is against PostgreSQL 8.4.0 from Debian
Lenny-backports. If this would be a welcome addition, I can port it forward
to the latest from postgresql.org.
Thanks in advance for your feedback.
Robert

On Thu, Sep 17, 2009 at 18:02, Robert Fleming <fleminra(at)gmail(dot)com> wrote:
> Following a discussion on the pgsql-admin list
> <http://archives.postgresql.org/pgsql-admin/2009-09/msg00075.php>, I have
> created a patch to (optionally) allow PostgreSQL to do a LDAP search to
> determine the user's DN (as is done in Apache, MediaWiki, Bugzilla, et al.)
> instead of building the DN from a prefix and suffix.
> This is necessary for schemas where the login attribute is not in the DN,
> such as is described here
> <http://www.ldapman.org/articles/intro_to_ldap.html#individual> (look for
> "name-based").  This patch is against PostgreSQL 8.4.0 from Debian
> Lenny-backports.  If this would be a welcome addition, I can port it forward
> to the latest from postgresql.org.
> Thanks in advance for your feedback.

This sounds like a very useful feature, and one that I can then remove
from my personal TODO list without having to do much work :-)

A couple of comments:

First of all, please read up on the PostgreSQL coding style, or at
least look at the code around yours. This doesn't look anything like
our standards.

Second, this appears to require an anonymous bind to the directory,
which is something we should not encourage people to enable on their
LDAP servers. I think we need to also take parameters with a DN and a
password to bind with in order to do the search, and then re-bind as
the user when found.

--
Magnus Hagander
Me: http://www.hagander.net/
Work: http://www.redpill-linpro.com/

On Thu, Sep 17, 2009 at 11:15 AM, Magnus Hagander <magnus(at)hagander(dot)net>wrote:

> On Thu, Sep 17, 2009 at 18:02, Robert Fleming <fleminra(at)gmail(dot)com> wrote:
> > Following a discussion on the pgsql-admin list
> > <http://archives.postgresql.org/pgsql-admin/2009-09/msg00075.php>, I
> have
> > created a patch to (optionally) allow PostgreSQL to do a LDAP search to
> > determine the user's DN (as is done in Apache, MediaWiki, Bugzilla, et
> al.)
> > instead of building the DN from a prefix and suffix.
> > This is necessary for schemas where the login attribute is not in the DN,
> > such as is described here
> > <http://www.ldapman.org/articles/intro_to_ldap.html#individual> (look
> for
> > "name-based"). This patch is against PostgreSQL 8.4.0 from Debian
> > Lenny-backports. If this would be a welcome addition, I can port it
> forward
> > to the latest from postgresql.org.
> > Thanks in advance for your feedback.
>
> This sounds like a very useful feature, and one that I can then remove
> from my personal TODO list without having to do much work :-)
>
> A couple of comments:
>
> First of all, please read up on the PostgreSQL coding style, or at
> least look at the code around yours. This doesn't look anything like
> our standards.
>

Sorry, the 8.1 manual said all contributions go through pgindent so I didn't
spend too much time on that. I see that the 8.4 manual clarifies that
pgindent won't get run till release time. In any case, I've re-formatted
the patch using the Emacs settings from the 8.1 manual (why are they gone
from the 8.4 manual)? It seems like most of the rest of the Coding
Conventions have to do with error reporting. Do please let me know if
there's something else I can do.

Second, this appears to require an anonymous bind to the directory,
> which is something we should not encourage people to enable on their
> LDAP servers. I think we need to also take parameters with a DN and a
> password to bind with in order to do the search, and then re-bind as
> the user when found.

The new patch implements the initial bind using new configuration parameters
"ldapbinddn" and "ldapbindpasswd". I've also added a "ldapsearchattribute"
just to be complete.

Robert

On Thu, Sep 17, 2009 at 6:24 PM, Robert Fleming <fleminra(at)gmail(dot)com> wrote:

> The new patch ...
>

s/printf/ereport(LOG,/

On Fri, Sep 18, 2009 at 02:24, Robert Fleming <fleminra(at)gmail(dot)com> wrote:
> On Thu, Sep 17, 2009 at 11:15 AM, Magnus Hagander <magnus(at)hagander(dot)net>
> wrote:
>>
>> On Thu, Sep 17, 2009 at 18:02, Robert Fleming <fleminra(at)gmail(dot)com> wrote:
>> > Following a discussion on the pgsql-admin list
>> > <http://archives.postgresql.org/pgsql-admin/2009-09/msg00075.php>, I
>> > have
>> > created a patch to (optionally) allow PostgreSQL to do a LDAP search to
>> > determine the user's DN (as is done in Apache, MediaWiki, Bugzilla, et
>> > al.)
>> > instead of building the DN from a prefix and suffix.
>> > This is necessary for schemas where the login attribute is not in the
>> > DN,
>> > such as is described here
>> > <http://www.ldapman.org/articles/intro_to_ldap.html#individual> (look
>> > for
>> > "name-based").  This patch is against PostgreSQL 8.4.0 from Debian
>> > Lenny-backports.  If this would be a welcome addition, I can port it
>> > forward
>> > to the latest from postgresql.org.
>> > Thanks in advance for your feedback.
>>
>> This sounds like a very useful feature, and one that I can then remove
>> from my personal TODO list without having to do much work :-)
>>
>> A couple of comments:
>>
>> First of all, please read up on the PostgreSQL coding style, or at
>> least look at the code around yours. This doesn't look anything like
>> our standards.
>
> Sorry, the 8.1 manual said all contributions go through pgindent so I didn't
> spend too much time on that.  I see that the 8.4 manual clarifies that
> pgindent won't get run till release time.  In any case, I've re-formatted
> the patch using the Emacs settings from the 8.1 manual (why are they gone
> from the 8.4 manual)?  It seems like most of the rest of the Coding
> Conventions have to do with error reporting.  Do please let me know if
> there's something else I can do.
>>
>> Second, this appears to require an anonymous bind to the directory,
>> which is something we should not encourage people to enable on their
>> LDAP servers. I think we need to also take parameters with a DN and a
>> password to bind with in order to do the search, and then re-bind as
>> the user when found.
>
> The new patch implements the initial bind using new configuration parameters
> "ldapbinddn" and "ldapbindpasswd".  I've also added a "ldapsearchattribute"
> just to be complete.

I've finally had the time to look at this patch some more, for the
current commitfest - sorry about the delay.

Other than minor style changes (make the indentation be the same as
the code around it), I noticed one fairly large issue.

The way that LDAP is re-initialized both breaks Windows (in the error
reporting part) and not as obvious but even more importantly, it
breaks TLS. If you enable TLS for LDAP it will only be used for the
search, not for the actual password check - which really removes the
point of it :-)

I assume we need the second ldap_init() because we want to do a new
ldap_simple_bind()? In that case, we realliy need to re-initialize the
whole connection, including TLS.

I also notice that it's hardcoded to retrieve the "uid" attribute,
while the one being searched for can be configured. ISTM it's better
to set both of these to the hba->ldapsearchattribute value - so we
won't fail if "uid" does not exist.

Also, as I'm sure you're aware there are no documentation updates included.

I'll be happy to work on this to get it ready for commit, or do you
want to do the updates?

--
Magnus Hagander
Me: http://www.hagander.net/
Work: http://www.redpill-linpro.com/

On Sun, Nov 29, 2009 at 13:05, Magnus Hagander <magnus(at)hagander(dot)net> wrote:
> On Fri, Sep 18, 2009 at 02:24, Robert Fleming <fleminra(at)gmail(dot)com> wrote:
>> On Thu, Sep 17, 2009 at 11:15 AM, Magnus Hagander <magnus(at)hagander(dot)net>
>> wrote:
>>>
>>> On Thu, Sep 17, 2009 at 18:02, Robert Fleming <fleminra(at)gmail(dot)com> wrote:
>>> > Following a discussion on the pgsql-admin list
>>> > <http://archives.postgresql.org/pgsql-admin/2009-09/msg00075.php>, I
>>> > have
>>> > created a patch to (optionally) allow PostgreSQL to do a LDAP search to
>>> > determine the user's DN (as is done in Apache, MediaWiki, Bugzilla, et
>>> > al.)
>>> > instead of building the DN from a prefix and suffix.
>>> > This is necessary for schemas where the login attribute is not in the
>>> > DN,
>>> > such as is described here
>>> > <http://www.ldapman.org/articles/intro_to_ldap.html#individual> (look
>>> > for
>>> > "name-based").  This patch is against PostgreSQL 8.4.0 from Debian
>>> > Lenny-backports.  If this would be a welcome addition, I can port it
>>> > forward
>>> > to the latest from postgresql.org.
>>> > Thanks in advance for your feedback.
>>>
>>> This sounds like a very useful feature, and one that I can then remove
>>> from my personal TODO list without having to do much work :-)
>>>
>>> A couple of comments:
>>>
>>> First of all, please read up on the PostgreSQL coding style, or at
>>> least look at the code around yours. This doesn't look anything like
>>> our standards.
>>
>> Sorry, the 8.1 manual said all contributions go through pgindent so I didn't
>> spend too much time on that.  I see that the 8.4 manual clarifies that
>> pgindent won't get run till release time.  In any case, I've re-formatted
>> the patch using the Emacs settings from the 8.1 manual (why are they gone
>> from the 8.4 manual)?  It seems like most of the rest of the Coding
>> Conventions have to do with error reporting.  Do please let me know if
>> there's something else I can do.
>>>
>>> Second, this appears to require an anonymous bind to the directory,
>>> which is something we should not encourage people to enable on their
>>> LDAP servers. I think we need to also take parameters with a DN and a
>>> password to bind with in order to do the search, and then re-bind as
>>> the user when found.
>>
>> The new patch implements the initial bind using new configuration parameters
>> "ldapbinddn" and "ldapbindpasswd".  I've also added a "ldapsearchattribute"
>> just to be complete.
>
> I've finally had the time to look at this patch some more, for the
> current commitfest - sorry about the delay.
>
> Other than minor style changes (make the indentation be the same as
> the code around it), I noticed one fairly large issue.
>
> The way that LDAP is re-initialized both breaks Windows (in the error
> reporting part) and not as obvious but even more importantly, it
> breaks TLS. If you enable TLS for LDAP it will only be used for the
> search, not for the actual password check - which really removes the
> point of it :-)
>
> I assume we need the second ldap_init() because we want to do a new
> ldap_simple_bind()? In that case, we realliy need to re-initialize the
> whole connection, including TLS.
>
> I also notice that it's hardcoded to retrieve the "uid" attribute,
> while the one being searched for can be configured. ISTM it's better
> to set both of these to the hba->ldapsearchattribute value - so we
> won't fail if "uid" does not exist.
>
> Also, as I'm sure you're aware there are no documentation updates included.
>
> I'll be happy to work on this to get it ready for commit, or do you
> want to do the updates?

Here's a patch with my work so far. Major points missing is the
sanitizing of the username and the docs.

--
Magnus Hagander
Me: http://www.hagander.net/
Work: http://www.redpill-linpro.com/

Magnus Hagander wrote:
> On Sun, Nov 29, 2009 at 13:05, Magnus Hagander <magnus(at)hagander(dot)net> wrote:
>
>> I'll be happy to work on this to get it ready for commit, or do you
>> want to do the updates?
>>
>
> Here's a patch with my work so far. Major points missing is the
> sanitizing of the username and the docs.
>
It looks like you did an initial review here already. Since we haven't
heard from Robert in a while and you seem interested in the patch, I
just updated this one to list you as the committer and marked it "ready
for committer". You can commit it or bounce it from there, but it's
obvious none of our other reviewers are going to be able to do anything
with it.

--
Greg Smith 2ndQuadrant Baltimore, MD
PostgreSQL Training, Services and Support
greg(at)2ndQuadrant(dot)com www.2ndQuadrant.com

On Sun, Dec 6, 2009 at 11:29 PM, Greg Smith <greg(at)2ndquadrant(dot)com> wrote:
> Magnus Hagander wrote:
>
> On Sun, Nov 29, 2009 at 13:05, Magnus Hagander <magnus(at)hagander(dot)net> wrote:
>
>
> I'll be happy to work on this to get it ready for commit, or do you
> want to do the updates?
>
>
> Here's a patch with my work so far. Major points missing is the
> sanitizing of the username and the docs.
>
>
> It looks like you did an initial review here already.  Since we haven't
> heard from Robert in a while and you seem interested in the patch, I just
> updated this one to list you as the committer and marked it "ready for
> committer".  You can commit it or bounce it from there, but it's obvious
> none of our other reviewers are going to be able to do anything with it.

I think we should mark this returned with feedback, since it sounds
like there are still open items.

...Robert

On Sat, Dec 12, 2009 at 02:41, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Sun, Dec 6, 2009 at 11:29 PM, Greg Smith <greg(at)2ndquadrant(dot)com> wrote:
>> Magnus Hagander wrote:
>>
>> On Sun, Nov 29, 2009 at 13:05, Magnus Hagander <magnus(at)hagander(dot)net> wrote:
>>
>>
>> I'll be happy to work on this to get it ready for commit, or do you
>> want to do the updates?
>>
>>
>> Here's a patch with my work so far. Major points missing is the
>> sanitizing of the username and the docs.
>>
>>
>> It looks like you did an initial review here already.  Since we haven't
>> heard from Robert in a while and you seem interested in the patch, I just
>> updated this one to list you as the committer and marked it "ready for
>> committer".  You can commit it or bounce it from there, but it's obvious
>> none of our other reviewers are going to be able to do anything with it.
>
> I think we should mark this returned with feedback, since it sounds
> like there are still open items.

I plan to clean up those open item smyself since there has been no
further feedback from the OP. Hopefully in time before the CF ends. So
please leave it for a few days more :-)

--
Magnus Hagander
Me: http://www.hagander.net/
Work: http://www.redpill-linpro.com/

On Sat, Dec 12, 2009 at 12:24, Magnus Hagander <magnus(at)hagander(dot)net> wrote:
> On Sat, Dec 12, 2009 at 02:41, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>> On Sun, Dec 6, 2009 at 11:29 PM, Greg Smith <greg(at)2ndquadrant(dot)com> wrote:
>>> Magnus Hagander wrote:
>>>
>>> On Sun, Nov 29, 2009 at 13:05, Magnus Hagander <magnus(at)hagander(dot)net> wrote:
>>>
>>>
>>> I'll be happy to work on this to get it ready for commit, or do you
>>> want to do the updates?
>>>
>>>
>>> Here's a patch with my work so far. Major points missing is the
>>> sanitizing of the username and the docs.
>>>
>>>
>>> It looks like you did an initial review here already.  Since we haven't
>>> heard from Robert in a while and you seem interested in the patch, I just
>>> updated this one to list you as the committer and marked it "ready for
>>> committer".  You can commit it or bounce it from there, but it's obvious
>>> none of our other reviewers are going to be able to do anything with it.
>>
>> I think we should mark this returned with feedback, since it sounds
>> like there are still open items.
>
> I plan to clean up those open item smyself since there has been no
> further feedback from the OP. Hopefully in time before the CF ends. So
> please leave it for a few days more :-)

I have applied the attached, rather heavily reworked, patch. It also
includes the required documentation.

--
Magnus Hagander
Me: http://www.hagander.net/
Work: http://www.redpill-linpro.com/