OpenLDAP is typically backed by a LMDB database (mdb). However it's backing datastore is actually pluggable. One of the most intriguing backends is back-sql, which allows LDAP data to be fetched from an ODBC (SQL) datasource. This lets us add a LDAP facade on top of database-backed applications, like JIRA and Confluence. This guide is specifically for getting OpenLDAP connecting to PostgreSQL on Ubuntu (20.04). Following these instructions should leave you with an OpenLDAP directory whose tree members are read directly from equivalent database tables.
Other Guides
The best guide I could find at time of writing ( ) is the OpenLDAP-POSTGRESQL HOWTO, written in 2001 and last updated in 2012. The HOWTO still fares well, given its age. It is weakest in the beginning, giving (I think) too many odbc options, outdated odbc advice, and too much compiling-from-source. Its strongest section is the last, a live example from a production system.
If you are using Ubuntu or Debian I suggest following this guide first, then refer back to the HOWTO's last section for a real example.
Recompile OpenLDAP with the SQL backend (back-sql)
First, get the OpenLDAP package source:
apt install dpkg-dev devscripts # Requirements for fetching and building source packages vim /etc/apt/sources.list # Uncomment the deb-src line to enable fetching source packages apt update # Refresh package cache mkdir openldap cd openldap apt source openldap cd openldap-2.4.49+dfsg apt build-dep slapd # Get build-time dependencies of OpenLDAP echo '--enable-sql' >> debian/configure.options # Enable SQL backend, which is why we're recompiling DEB_BUILD_OPTIONS='nostrip noopt parallel=4 nocheck' DFSG_NONFREE=true debuild --no-lintian -i -us -uc -b
The final build command needs a bit of explanation:
- -us is --unsigned-source – do not sign the source package
-uc is --unsigned-changes
-b is --build=binary
-i is passed to dpkg-source
--no-lintian prevents a slow 'lint' operation - DFSG_NONFREE=true prevents the build breaking (can't remember why - check debian/rules)
- Within DEB_BUILD_OPTIONS:
nostrip noopt leaves debug symbols in the resulting binaries. This is needed for later running slapd under 'gdb', which is something you're unfortunately likely to need.
parallel=4 speed up the build a bit
nocheck avoid running the tests on every build. For slapd they are very slow.
Now install the built packages:
apt install psmisc # This is a runtime dependency of slapd. Normally when you 'apt install slapd' this dependency is fetched automatically; however since we're installing directly ('dpkg -i') we need to install it manually.
dpkg -i ../*.deb # Install OpenLDAP packages we just built.
Ensure that slapd was built with 'sql' support:
$ slapd -VVV
@(#) $OpenLDAP: slapd (Ubuntu) (Mar 6 2020 14:39:12) $
Debian OpenLDAP Maintainers <pkg-openldap-devel@lists.alioth.debian.org>
Included static backends:
config
ldif
sql
Create a sample database
Install Postgres and create a sample 'ldapsql' database:
apt install postgresql-12 postgresql-client-12 su - postgres # Switch from root to 'postgres' createuser -P ldapsql # Create 'ldapsql' postgres user. Enter 'ldapsql' for the password. createdb -O ldapsql ldapsql # Create 'ldapsql' database owned by 'ldapsql' logout # Switch from 'postgres' back to root
Load the back-sql sample database:
cd ~/openldap/openldap-2.4.49+dfsg/servers/slapd/back-sql/rdbms_depend/pgsql export PGHOST=localhost PGUSER=ldapsql PGPASSWORD=ldapsql PGDATABASE=ldapsql cat testdb_create.sql testdb_data.sql backsql_create.sql testdb_metadata.sql | psql
Verify that things look correct:
$ psql ldapsql=> select * from ldap_entries; id | dn | oc_map_id | parent | keyval ----+-----------------------------------------+-----------+--------+-------- 1 | dc=example,dc=com | 3 | 0 | 1 2 | cn=Mitya Kovalev,dc=example,dc=com | 1 | 1 | 1 3 | cn=Torvlobnor Puzdoy,dc=example,dc=com | 1 | 1 | 2 4 | cn=Akakiy Zinberstein,dc=example,dc=com | 1 | 1 | 3 5 | documentTitle=book1,dc=example,dc=com | 2 | 1 | 1 6 | documentTitle=book2,dc=example,dc=com | 2 | 1 | 2 7 | ou=Referral,dc=example,dc=com | 4 | 1 | 1 (7 rows) ldapsql=> select * from persons; id | name | surname | password ----+------------+-------------+---------- 1 | Mitya | Kovalev | mit 2 | Torvlobnor | Puzdoy | 3 | Akakiy | Zinberstein | (3 rows)
Connect with ODBC
apt install unixodbc odbc-postgresql cat - <<EOF >> /etc/odbc.ini [ldapsql] Description = Example for OpenLDAP's back-sql Driver = PostgreSQL ANSI Trace = No Database = ldapsql Servername = localhost UserName = ldapsql Password = ldapsql Port = 5432 ;Protocol = 6.4 ReadOnly = No RowVersioning = No ShowSystemTables = No ShowOidColumn = No FakeOidIndex = No ConnSettings = EOF
Connect with 'isql' to validate the odbc connection:
root@openldap2:/# isql -m10 ldapsql <<< 'select * from persons' +---------------------------------------+ | Connected! | | | | sql-statement | | help [tablename] | | quit | | | +---------------------------------------+ SQL> select * from persons +-----------+-----------+-----------+-----------+ | id | name | surname | password | +-----------+-----------+-----------+-----------+ | 1 | Mitya | Kovalev | mit | | 2 | Torvlobnor| Puzdoy | | | 3 | Akakiy | Zinberstei| | +-----------+-----------+-----------+-----------+ SQLRowCount returns 3 3 rows fetched
Set up OpenLDAP
OpenLDAP has traditionally been configured in a slapd.conf(5) file. Since 2.3 OpenLDAP has adopted the newer slapd-config(5) format, where the configuration is itself managed as a directory tree, managed by LDAP.
The new format is horrible; instead of just editing a file, every change now needs to be translated to LDIF.
Fortunately you don't need to use it:
rm -r /etc/ldap/slapd.d/ # Begone, new format! vim /etc/default/slapd # Set SLAPD_CONF=/etc/ldap/slapd.conf systemctl restart slapd
Create a new slapd.conf from scratch.
Plain mdb-backed LDAP
First we'll get a normal mdb-backed LDAP working before adding a SQL backend:
cat - <<EOF > /etc/ldap/slapd.conf
include /etc/ldap/schema/core.schema
include /etc/ldap/schema/cosine.schema
include /etc/ldap/schema/inetorgperson.schema
pidfile /var/run/slapd/slapd.pid
argsfile /var/run/slapd/slapd.args
modulepath /usr/lib/ldap
moduleload back_mdb
database mdb
suffix "dc=test,dc=com"
rootdn "cn=admin,dc=test,dc=com"
rootpw secret
# The database directory MUST exist prior to running slapd AND
# should only be accessible by the slapd and slap tools.
# Mode 700 recommended.
directory /var/lib/ldap
# Indices to maintain
index objectClass eq
EOF
systemctl restart slapd # Restart; 'journalctl -fu slapd' if you have problems.
cat - <<EOF > /tmp/init.ldif
dn: dc=test,dc=com
objectClass: top
objectClass: dcObject
objectClass: organization
o: Test Organization
dc: Test
dn: cn=admin,dc=test,dc=com
objectClass: simpleSecurityObject
objectClass: organizationalRole
cn: admin
description: LDAP administrator
userPassword: $(slappasswd -h {SSHA} -s hunter2)
EOF
ldapadd -f /tmp/init.ldif -x -D 'cn=admin,dc=test,dc=com' -w secret
We should now be able to bind as cn=admin using either 'secret' or 'hunter2':
# ldapsearch -x -b 'dc=test,dc=com' -D 'cn=admin,dc=test,dc=com' -w hunter2 # extended LDIF # # LDAPv3 # base <dc=test,dc=com> with scope subtree # filter: (objectclass=*) # requesting: ALL # # test.com dn: dc=test,dc=com objectClass: top objectClass: dcObject objectClass: organization o: Test Organization dc: Test # admin, test.com dn: cn=admin,dc=test,dc=com objectClass: simpleSecurityObject objectClass: organizationalRole cn: admin description: LDAP administrator userPassword:: e1NTSEF9czRHRHZ4TlNTMWk1eTI0K2cyd3pnTVpFclY4TGpzN2s= # search result search: 2 result: 0 Success # numResponses: 3 # numEntries: 2
Add a SQL backend
Now let's add a SQL backend. OpenLDAP can have multiple backends - we'll leave our dc=test,dc=com backend configured, and add a new SQL backend rooted at dc=example,dc=com :
sed -e 's/^ //g' - <<EOF >> /etc/ldap/slapd.conf
# SQL Backend
database sql
suffix "dc=example,dc=com"
rootdn "cn=admin,dc=example,dc=com"
rootpw secret
dbname ldapsql
dbuser ldapsql
dbpasswd ldapsql
insentry_stmt "insert into ldap_entries (id,dn,oc_map_id,parent,keyval) values ((select max(id)+1 from ldap_entries),?,?,?,?)"
upper_func "upper"
strcast_func "text"
concat_pattern "?||?"
#subtree_cond "ldap_entries.dn LIKE CONCAT('%',?)"
has_ldapinfo_dn_ru no
EOF
systemctl restart slapd # If unsuccessful, 'journalctl -fu slapd &' and try again
The sed command is to trip the blank space ' ' that Confluence is adding when this block is copied and pasted :/
Tell AppArmor to let slapd access odbc.ini
Initially when I added the SQL backend, my slapd refused to start with an unhelpful error:
backend_startup_one (type=sql, suffix="dc=jira"): bi_db_open failed! (1)
More verbose logs can be obtained by editing /etc/default/slapd and setting SLAPD_OPTIONS="-s7". That yielded:
==>backsql_get_db_conn()
==>backsql_open_db_handle()
backsql_open_db_handle(): SQLConnect() to database "ldapsql" failed.
Return code: -1
nativeErrCode=0 SQLengineState=IM002[unixODBC][Driver Manager]Data source name not found, and no default driver specified msg="[unixODBC][Driver Manager]Data source name not found, and no default driver specified"
backsql_db_open(): connection failed, exiting
backend_startup_one (type=sql, suffix="dc=example,dc=com"): bi_db_open failed! (1)
slapd shutdown: initiated
==>backsql_db_close()
<==backsql_db_close()
slapd destroy: freeing system resources.
==>backsql_db_destroy()
==>backsql_free_db_env()
<==backsql_free_db_env()
==>destroy_schema_map()
<==destroy_schema_map()
<==backsql_db_destroy()
I eventually stumbled upon this post, which identified the problem: Ubuntu's AppArmor is preventing slapd from accessing /etc/odbc.ini
The fix is:
cat - <<EOF > /etc/apparmor.d/local/usr.sbin.slapd # Let slapd access odbc config files, and (for MySQL) the mysql unix socket. # https://ubuntuforums.org/showthread.php?p=8248430#post8248430 /etc/odbc.ini r, /etc/odbcinst.ini r, /var/run/mysqld/mysqld.sock w, EOF systemctl restart apparmor systemctl restart slapd
Testing your SQL-backed LDAP
If everything went correctly, you should now be able to query your database-backed directory tree:
root@openldap2:/# ldapsearch -x -b 'dc=example,dc=com' '(objectclass=inetOrgPerson)' objectclass cn sn -D 'cn=admin,dc=example,dc=com' -w secret # extended LDIF # # LDAPv3 # base <dc=example,dc=com> with scope subtree # filter: (objectclass=inetOrgPerson) # requesting: objectclass cn sn # # Akakiy Zinberstein, example.com dn: cn=Akakiy Zinberstein,dc=example,dc=com objectClass: inetOrgPerson objectClass: pkiUser cn: Akakiy Zinberstein sn: Zinberstein # Mitya Kovalev, example.com dn: cn=Mitya Kovalev,dc=example,dc=com objectClass: inetOrgPerson cn: Mitya Kovalev sn: Kovalev # Torvlobnor Puzdoy, example.com dn: cn=Torvlobnor Puzdoy,dc=example,dc=com objectClass: inetOrgPerson cn: Torvlobnor Puzdoy sn: Puzdoy # search result search: 2 result: 0 Success # numResponses: 4 # numEntries: 3
At this point you might like to download a LDAP browser like Apache Directory Studio. Point it at localhost with your dc=example,dc=com base DN:
Startup dependency?
We have now introduced a startup dependency between Postgres and OpenLDAP. If OpenLDAP happens to start before Postgres it up it will fail. I know we need:
After=postgresql@12-main.service Wants=postgresql@12-main.service
but I'm not sure how to add this, given slapd is still started as a sysvinit startup file.