Top-level config entry of PAM PTA plugin is ignored when multiple instances are configured

[389-ds-bot]

Cloned from Pagure issue: https://pagure.io/389-ds-base/issue/492

• Created at 2012-10-13 14:54:53 by jrusnack
• Closed as Invalid
• Assigned to rmeggins (@richm)
• Associated bugzillas
  • https://bugzilla.redhat.com/show_bug.cgi?id=868167

---

Description of problem:

One of new added functionalities of PAM PTA is support for multiple configuration entries. To be backward compatible, top-level configuration entry cn=PAM Pass Through Auth,cn=plugins,cn=config is still valid configuration entry. In addition to that, each child is also expected to be PAM PTA config entry. However, top-level config entry is being ignored when a child entry is present, and only child entries configure plugins behavior.

Version-Release number of selected component (if applicable):
tested on 389-ds-base-1.2.11.15-2.el6.x86_64

How reproducible:
always

Steps to Reproduce:
One way to reproduce is to setup top-level config entry to include ldap user and set child config entry to exclude user. Both instances have fallback set to false. When user tries to bind, top-level entry is ignored, and user binds. If however child config entry is set to include user entry, then user bind fails on 32 - user does no exist in PAM.

USERD="uid=tuserD, ..."

1. Add user $USERD
   ldapmodify -h $IP -p $PORT -D "cn=directory manager" -w Secret123 <<EOF
   dn: $USERD
   changetype: add
   ...
   userPassword: password
   EOF

2. configure top-level entry to include $USERD and deny fallback
   ldapmodify -h $IP -p $PORT -D "cn=directory manager" -w Secret123 <<EOF
   dn: cn=PAM Pass Through Auth,cn=plugins,cn=config
   changetype: modify
   replace: nsslapd-pluginEnabled
   nsslapd-pluginEnabled: on

replace: pamFallback
pamFallback: FALSE

replace: pamIncludeSuffix
pamIncludeSuffix: $USERD
EOF

3. configure child entry to exclude $USERD and deny fallback
   ldapmodify -h $IP -p $PORT -D "cn=directory manager" -w Secret123 <<EOF
   dn: cn=inst2,cn=PAM Pass Through Auth,cn=plugins,cn=config
   changetype: add
   cn: test1
   objectClass: pamConfig
   objectClass: top
   pamIDMapMethod: RDN DN ENTRY
   pamFallback: FALSE
   pamSecure: FALSE
   pamService: ldapserver
   pamExcludeSuffix: $USERD
   pamMissingSuffix: ALLOW
   pamIDAttr: uid
   EOF

4. restart server
   service dirsrv restart

5. try to bind as $USERD
   ldapsearch -h $IP -p $PORT -D "$USERD" -w password -b "$USERD"

Actual results:
echo $?
0

Expected results:
ldap_bind: No such object (32)
additional info: User id [tuserD] for bind DN [uid=tuserD,dc=suf1,dc=example,dc=com] does not exist in PAM

Additional info:
https://fedorahosted.org/389/attachment/ticket/181/0001-ticket-181-Allow-PAM-passthru-plug-in-to-have-multip.patch: "When the normal area in cn=config is used, both the top-level PAM passthru plug-in config entry and it's children are considered to
be config entries."

[389-ds-bot]

Comment from nkinder (@nkinder) at 2012-10-30 00:44:27

Linked to Bugzilla bug: https://bugzilla.redhat.com/show_bug.cgi?id=868167 (''Red Hat Enterprise Linux 6'')

[389-ds-bot]

Comment from nkinder (@nkinder) at 2012-11-06 22:32:59

This problem could be related to the fact that you are using the DN of "user D" as a suffix in the PAM config. This is not correct. The include/exclude suffixes are supposed to be top-level suffixes, not any arbitrary DN within your tree.

This needs to be tested using valid suffixes in the config.

[389-ds-bot]

Comment from nkinder (@nkinder) at 2012-11-06 22:58:52

The problem here is that you have 2 overlapping config entries. The logic isn't designed to have the PAM passthru plug-in fall through when a configuration entry fails to work for authenticating a user. When a bind attempt comes in, the logic is as follows:

• Loop through the PAM passthru config entries to see if the include/exclude suffix and filter settings apply to the bind target.
• Use the first matching config entry with PAM to authenticate user.
• Return BIND result to client.

There is no fallback logic. In your test scenario, the child config entry (cn=inst2,...) is checked first when we are looping through the config entries. When you exclude $USERD in the child entry, that config doesn't apply, so the top-level config entry is used. When you change the child to include $USERD, the child entry does apply, and that config entry is used instead of the top-level config.

[389-ds-bot]

Comment from nkinder (@nkinder) at 2012-11-06 23:22:37

The behavior described in comment3 is by design. The intention of allowing multiple PAM passthru configuration settings is to have separate configuration for separate entries (via suffix, filter, or a combination of the two). Having multiple configuration entries that apply to the same set of bind target entries is beyond the scope of the current design. This also matches up with the way most of the other DS plug-ins work that support multiple config entries.

I'm closing this as INVALID.

[389-ds-bot]

Comment from nkinder (@nkinder) at 2017-02-11 23:09:31

Metadata Update from @nkinder:

• Issue assigned to richm
• Issue set to the milestone: N/A