s3: shortcut uid_to_sid when "ldapsam:trusted = yes"

The normal uid_to_sid behaviour is to call sys_getpwuid()
to get the name for the given uid and then call the
getsampwnam passdb method for the resulting name.

In the ldapsam:trusted case we can reduce the uid_to_sid
operation to one simple search for the uidNumber attribute
and only get the sambaSID attribute from the correspoinding
LDAP object. This reduces the number of ldap roundtrips
for this operation.

Michael
(cherry picked from commit 37dcc8a400ea41fb0a0559c9922cc41ac28ad045)

Signed-off-by: Stefan Metzmacher <metze@samba.org>
(cherry picked from commit 91e40dfde99b08158b809590c44c22b503403157)

1 files changed, 75 insertions, 0 deletions

diff --git a/source3/passdb/pdb_ldap.c b/source3/passdb/pdb_ldap.c
index 40225555d7b..66db0eba02a 100644
--- a/source3/passdb/pdb_ldap.c
+++ b/source3/passdb/pdb_ldap.c
@@ -4971,6 +4971,80 @@ static bool ldapsam_sid_to_id(struct pdb_methods *methods,
 	return ret;
 }
 
+/**
+ * Find the SID for a uid.
+ * This is shortcut is only used if ldapsam:trusted is set to true.
+ */
+static bool ldapsam_uid_to_sid(struct pdb_methods *methods, uid_t uid,
+			       DOM_SID *sid)
+{
+	struct ldapsam_privates *priv =
+		(struct ldapsam_privates *)methods->private_data;
+	char *filter;
+	const char *attrs[] = { "sambaSID", NULL };
+	LDAPMessage *result = NULL;
+	LDAPMessage *entry = NULL;
+	bool ret = false;
+	char *user_sid_string;
+	DOM_SID *user_sid;
+	int rc;
+	TALLOC_CTX *tmp_ctx = talloc_stackframe();
+
+	filter = talloc_asprintf(tmp_ctx,
+				 "(&(uidNumber=%u)"
+				 "(objectClass=%s)"
+				 "(objectClass=%s))",
+				 (unsigned int)uid,
+				 LDAP_OBJ_POSIXACCOUNT,
+				 LDAP_OBJ_SAMBASAMACCOUNT);
+	if (filter == NULL) {
+		DEBUG(3, ("talloc_asprintf failed\n"));
+		goto done;
+	}
+
+	rc = smbldap_search_suffix(priv->smbldap_state, filter, attrs, &result);
+	if (rc != LDAP_SUCCESS) {
+		goto done;
+	}
+	talloc_autofree_ldapmsg(tmp_ctx, result);
+
+	if (ldap_count_entries(priv2ld(priv), result) != 1) {
+		DEBUG(3, ("ERROR: Got %d entries for uid %u, expected one\n",
+			   ldap_count_entries(priv2ld(priv), result),
+			   (unsigned int)uid));
+		goto done;
+	}
+
+	entry = ldap_first_entry(priv2ld(priv), result);
+
+	user_sid_string = smbldap_talloc_single_attribute(priv2ld(priv), entry,
+							  "sambaSID", tmp_ctx);
+	if (user_sid_string == NULL) {
+		DEBUG(1, ("Could not find sambaSID in object '%s'\n",
+			  smbldap_talloc_dn(tmp_ctx, priv2ld(priv), entry)));
+		goto done;
+	}
+
+	user_sid = string_sid_talloc(tmp_ctx, user_sid_string);
+	if (user_sid == NULL) {
+		DEBUG(3, ("Error calling sid_string_talloc for sid '%s'\n",
+			  user_sid_string));
+		goto done;
+	}
+
+	sid_copy(sid, user_sid);
+
+	store_uid_sid_cache(sid, uid);
+	idmap_cache_set_sid2uid(sid, uid);
+
+	ret = true;
+
+ done:
+	TALLOC_FREE(tmp_ctx);
+	return ret;
+}
+
+
 /*
  * The following functions is called only if
  * ldapsam:trusted and ldapsam:editposix are
@@ -6330,6 +6404,7 @@ NTSTATUS pdb_init_ldapsam(struct pdb_methods **pdb_method, const char *location)
 			ldapsam_enum_group_memberships;
 		(*pdb_method)->lookup_rids = ldapsam_lookup_rids;
 		(*pdb_method)->sid_to_id = ldapsam_sid_to_id;
+		(*pdb_method)->uid_to_sid = ldapsam_uid_to_sid;
 
 		if (lp_parm_bool(-1, "ldapsam", "editposix", False)) {
 			(*pdb_method)->create_user = ldapsam_create_user;