This is a multi-part message in MIME format. --------------090400040509090303060604 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit
ando@sys-net.it wrote:
jsafrane@redhat.com wrote:
Following ldapsearch crashes when referral chasing is enabled in very unusual environment with many AD servers referring to each other (I had to increase refhoplimit to chase all the referrals).
Thanks for the detailed report. However, IMHO, automatic referral chasing Is Broken. Clients should explicitly chase them, possibly providing some interactive means for rebinding. This is what is currently done, for example, by slapd when using slapo-chain(5), and what should be done by proxy backends as well.
nss_ldap does not have an option to chase referrals, it depends on ldap libraries to do the dirty job. I think that referral chasing in OpenLDAP libraries works pretty well apart my crash. Is there anything I am not aware of? Instead adding new features to nss_ldap, it would be better to fix OpenLDAP, more applications would benefit from that.
I tried to work around the crash, see patch attached (apply to current 2.4 branch in CVS). I was not able to prevent deleting connections during referral chasing (I admit I got lost in the code and various code paths). So I added very simple mechanism to detect possibly freed connection and restart the loop in wait4msg(). It seems to help in my scenario.
Jan
--------------090400040509090303060604 Content-Type: text/plain; name="openldap-2.4-refer-crash.patch" Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="openldap-2.4-refer-crash.patch"
Index: libraries/libldap/ldap-int.h =================================================================== RCS file: /repo/OpenLDAP/pkg/ldap/libraries/libldap/ldap-int.h,v retrieving revision 1.168.2.9 diff -u -r1.168.2.9 ldap-int.h --- libraries/libldap/ldap-int.h 8 Nov 2008 00:14:45 -0000 1.168.2.9 +++ libraries/libldap/ldap-int.h 14 Jan 2009 14:54:09 -0000 @@ -401,6 +401,7 @@
LDAPConn *ld_defconn; /* default connection */ LDAPConn *ld_conns; /* list of server connections */ + int ld_conns_version; /* unique id tracking deletions in ld_conns list */ void *ld_selectinfo; /* platform specifics for select */ }; #define LDAP_VALID(ld) ( (ld)->ld_valid == LDAP_VALID_SESSION ) Index: libraries/libldap/request.c =================================================================== RCS file: /repo/OpenLDAP/pkg/ldap/libraries/libldap/request.c,v retrieving revision 1.125.2.12 diff -u -r1.125.2.12 request.c --- libraries/libldap/request.c 8 Nov 2008 01:15:17 -0000 1.125.2.12 +++ libraries/libldap/request.c 14 Jan 2009 14:54:09 -0000 @@ -697,6 +698,7 @@ } prevlc = tmplc; } + ld->ld_conns_version++; #ifdef LDAP_R_COMPILE ldap_pvt_thread_mutex_unlock( &ld->ld_conn_mutex ); #endif Index: libraries/libldap/result.c =================================================================== RCS file: /repo/OpenLDAP/pkg/ldap/libraries/libldap/result.c,v retrieving revision 1.124.2.14 diff -u -r1.124.2.14 result.c --- libraries/libldap/result.c 10 Nov 2008 17:39:16 -0000 1.124.2.14 +++ libraries/libldap/result.c 14 Jan 2009 14:54:09 -0000 @@ -396,6 +396,7 @@ if ( lc->lconn_status == LDAP_CONNST_CONNECTED && ldap_is_read_ready( ld, lc->lconn_sb ) ) { + int version = ld->ld_conns_version; #ifdef LDAP_R_COMPILE ldap_pvt_thread_mutex_unlock( &ld->ld_conn_mutex ); #endif @@ -403,12 +404,12 @@ #ifdef LDAP_R_COMPILE ldap_pvt_thread_mutex_lock( &ld->ld_conn_mutex ); #endif - if ( lc == NULL ) { + if ( version != ld->ld_conns_version || lc == NULL ) { /* if lc gets free()'d, * there's no guarantee - * lc->lconn_next is still + * lc or lc->lconn_next is still * sane; better restart - * (ITS#4405) */ + * (ITS#4405, ITS#5853) */ lc = ld->ld_conns;
/* don't get to next conn! */
--------------090400040509090303060604--
-
jsafrane＠redhat.com