We encountered a back-ldap assertion failure with the back-ldap as a proxy to a remote Active Directory on Windows 2003 R2. The assertion failure occurred when the slapd server was checking ACLs via the rwm overlay. Snippet of the stack trace:
Thread 1 (Thread 32267): .... #2 0x0000003c354296e6 in __assert_fail () from /lib64/libc.so.6 #3 0x00002ac57daaf6c1 in ldap_back_dobind_int (lcp=0x42f70170, op=0x42f702f0, rs=0x42f700a0, sendok=LDAP_BACK_GETCONN, retries=0, dolock=1) at /home/build/sol-2.4.23.101221/sol24x/ldap24/servers/slapd/back-ldap/bind.c:1389 #4 0x00002ac57daafda0 in ldap_back_dobind (lcp=0x42f70170, op=0x42f702f0, rs=0x42f700a0, sendok=LDAP_BACK_DONTSEND) at /home/build/sol-2.4.23.101221/sol24x/ldap24/servers/slapd/back-ldap/bind.c:1572 #5 0x00002ac57daac7a7 in ldap_back_entry_get (op=0x42f702f0, ndn=0x42f701d0, oc=0x0, at=0x135ad370, rw=0, ent=0x42f70a58)
Analysis of the assertion failure:
The ldap_back_entry_get() function, back-ldap/search.c, is called for ACL entries, via rwm overlay. The function sets op->o_do_not_cache to 1 before calling into ldap_back_dobind():
/* Tell getconn this is a privileged op */ do_not_cache = op->o_do_not_cache; tag = op->o_tag; /* do not cache */ op->o_do_not_cache = 1; /* ldap_back_entry_get() is an entry lookup, so it does not need * to know what the entry is being looked up for */ op->o_tag = LDAP_REQ_SEARCH; rc = ldap_back_dobind( &lc, op, &rs, LDAP_BACK_DONTSEND );
The ldap_back_dobind() function calls ldap_back_dobind_int() for bind, back-ldap/bind.c. The following ldap_back_dobind_int() code is destined for assertion failure, if op->o_do_not_cache flag is set and there is no valid binddn and bindcred returned by ldap_back_getconn(). Setting an invalid LDAP URI for the remote AD Windows box is such a case.
ldap_back_dobind_int(…) { ... if (sendok & LDAP_BACK_GETCONN) { … lc = ldap_back_getconn(op, rs, sendoff, &binddn, &bindcred); ... } …
if ( LDAP_BACK_CONN_ISIDASSERT( lc ) ) { if ( BER_BVISEMPTY( &binddn ) && BER_BVISEMPTY( &bindcred ) ) { /* if we got here, it shouldn't return result */ rc = ldap_back_is_proxy_authz( op, rs, LDAP_BACK_DONTSEND, &binddn, &bindcred );
/* ldap_back_is_proxy_authz always returns 0 when op->o_do_not_cache is set, see below */ assert( rc == 1 );------> assertion failure } rc = ldap_back_proxy_authz_bind( lc, op, rs, sendok, &binddn, &bindcred ); … } }
When the op->o_do_not_cache flag is set, the ldap_back_is_proxy_authz() function always returns 0.
ldap_back_is_proxy_authz( ... ) { ... int dobind = 0;
if ( op->o_conn == NULL || op->o_do_not_cache ) { goto done; } ... done:; return dobind; <--- always returns 0 }
Ted C. Cheng Symas Corporation