From: Thomas Reim <reimth@xxxxxxxxx>
From: Thomas Reim <reimth@xxxxxxxxx>
Cyrus SASL supports data encryption in GSSAPI (with Kerberos V) mode using an
SASL data security layer according to IETF RFC 2078. This security layer
provides for traffic encryption during authentication and authorization towards
an OpenLDAP based server and for subsequent encryption of data traffic for the
LDAP session. Current automounter does not implement SASL security layer
encryption and only relies on TLS to protect LDAP communication.
OpenLDAP libldap if compiled with Cyrus SASL supports negotiation of an SASL
data security layer based encryption of LDAP traffic. libldap also provides
automatic negotiation of the best suited SASL mechanism taking into account
application required defaults.
Since version 4.4 Samba AD domain controllers default settings only allow for
simple SASL binds over TLS encrypted connections or SASL binds with sign or
seal, i. e. data security layer encryption, over unencrypted connections.
Therefore, current automounter cannot fetch autofs maps from Samba AD DCs
using SASL anymore without setting Samba configuration parameter "ldap server
require strong auth" to "no" or "allow_sasl_over_tls".
This patch updates automounter to let OpenLDAP and Cyrus SASL handle SASL
binding and traffic security configuration. Proposed changes are backward
compatible for clients that use LDAP libaries different from LDAP. When using
SASL mechanism GSSAPI or simple authentication with TLS encryption automounter
seamlessly interworks with latest Samba AD DCs.
Signed-off-by: Thomas Reim <reimth@xxxxxxxxx>
Signed-off-by: Ian Kent <raven@xxxxxxxxxx>
---
CHANGELOG | 1
include/lookup_ldap.h | 6 ++
modules/cyrus-sasl.c | 150 +++++++++++++++++++++++++++++++++++++++++++++++++
modules/lookup_ldap.c | 137 ++++++++++++++++++++++++++++++++++++++++++++-
4 files changed, 292 insertions(+), 2 deletions(-)
diff --git a/CHANGELOG b/CHANGELOG
index 98ec78a9..52da6256 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -31,6 +31,7 @@
- fix a couple of null cache locking problems.
- restore gcc flags after autoconf Kerberos 5 check.
- prepare for OpenLDAP SASL binding.
+- let OpenLDAP handle SASL binding.
19/10/2021 autofs-5.1.8
- add xdr_exports().
diff --git a/include/lookup_ldap.h b/include/lookup_ldap.h
index 3a107782..9c3e8627 100644
--- a/include/lookup_ldap.h
+++ b/include/lookup_ldap.h
@@ -129,6 +129,12 @@ int autofs_sasl_bind(unsigned logopt, struct ldap_conn *conn, struct lookup_cont
void autofs_sasl_unbind(struct ldap_conn *conn, struct lookup_context *ctxt);
void autofs_sasl_dispose(struct ldap_conn *conn, struct lookup_context *ctxt);
void autofs_sasl_done(void);
+int sasl_do_kinit(unsigned logopt, struct lookup_context *ctxt);
+#ifdef WITH_LDAP_CYRUS_SASL
+void autofs_ldap_sasl_freedefs(void *defaults);
+void *autofs_ldap_sasl_defaults(LDAP *ld, char *mech, char *realm, char *authcid, char *passwd, char *authzid );
+int autofs_ldap_sasl_interact(LDAP *ld, unsigned flags, void *defaults, void *in );
+#endif
/* cyrus-sasl-extern */
int do_sasl_extern(LDAP *ldap, struct lookup_context *ctxt);
#endif
diff --git a/modules/cyrus-sasl.c b/modules/cyrus-sasl.c
index 738e363f..11e3f76a 100644
--- a/modules/cyrus-sasl.c
+++ b/modules/cyrus-sasl.c
@@ -233,6 +233,151 @@ get_server_SASL_mechanisms(unsigned logopt, LDAP *ld)
return mechanisms;
}
+#ifdef WITH_LDAP_CYRUS_SASL
+typedef struct autofs_ldap_sasl_defaults_s {
+ char *mech;
+ char *realm;
+ char *authcid;
+ char *passwd;
+ char *authzid;
+} ldapSASLdefaults;
+
+
+void autofs_ldap_sasl_freedefs(void *defaults)
+{
+ ldapSASLdefaults *defs = defaults;
+
+ assert(defs != NULL);
+
+ if (defs->mech)
+ ber_memfree(defs->mech);
+ if (defs->realm)
+ ber_memfree(defs->realm);
+ if (defs->authcid)
+ ber_memfree(defs->authcid);
+ if (defs->passwd)
+ ber_memfree(defs->passwd);
+ if (defs->authzid)
+ ber_memfree(defs->authzid);
+
+ ber_memfree(defs);
+}
+
+void *
+autofs_ldap_sasl_defaults(LDAP *ld,
+ char *mech,
+ char *realm,
+ char *authcid,
+ char *passwd,
+ char *authzid)
+{
+ ldapSASLdefaults *defaults;
+
+ defaults = ber_memalloc(sizeof(ldapSASLdefaults));
+
+ if (defaults == NULL)
+ return NULL;
+
+ defaults->mech = mech ? ber_strdup(mech) : NULL;
+ defaults->realm = realm ? ber_strdup(realm) : NULL;
+ defaults->authcid = authcid ? ber_strdup(authcid) : NULL;
+ defaults->passwd = passwd ? ber_strdup(passwd) : NULL;
+ defaults->authzid = authzid ? ber_strdup(authzid) : NULL;
+
+ if (defaults->mech == NULL)
+ ldap_get_option(ld, LDAP_OPT_X_SASL_MECH, &defaults->mech);
+ if (defaults->realm == NULL)
+ ldap_get_option(ld, LDAP_OPT_X_SASL_REALM, &defaults->realm);
+ if (defaults->authcid == NULL)
+ ldap_get_option(ld, LDAP_OPT_X_SASL_AUTHCID, &defaults->authcid);
+ if (defaults->authzid == NULL)
+ ldap_get_option(ld, LDAP_OPT_X_SASL_AUTHZID, &defaults->authzid);
+
+ return defaults;
+}
+
+static int
+interaction(unsigned flags,
+ sasl_interact_t *interact,
+ ldapSASLdefaults *defaults)
+{
+ switch (interact->id) {
+ case SASL_CB_GETREALM:
+ if (defaults->realm)
+ interact->result = defaults->realm;
+ else if (interact->defresult)
+ interact->result = interact->defresult;
+ else
+ interact->result = "";
+ interact->len = strlen(interact->result);
+ break;
+
+ case SASL_CB_USER:
+ if (defaults->authzid)
+ interact->result = defaults->authzid;
+ else if (interact->defresult)
+ interact->result = interact->defresult;
+ else
+ interact->result = "";
+ interact->len = strlen(interact->result);
+ break;
+
+ case SASL_CB_PASS:
+ if (defaults->passwd)
+ interact->result = defaults->passwd;
+ else if (interact->defresult)
+ interact->result = interact->defresult;
+ else
+ interact->result = "";
+ interact->len = strlen(interact->result);
+ break;
+
+ case SASL_CB_AUTHNAME:
+ if (defaults->authcid)
+ interact->result = defaults->authcid;
+ else if (interact->defresult)
+ interact->result = interact->defresult;
+ else
+ interact->result = "";
+ interact->len = strlen(interact->result);
+ break;
+ }
+
+ return LDAP_SUCCESS;
+}
+
+int
+autofs_ldap_sasl_interact(LDAP *ld,
+ unsigned flags,
+ void *defaults,
+ void *interact)
+{
+ ldapSASLdefaults *deflts = (ldapSASLdefaults*) defaults;
+ sasl_interact_t *in = (sasl_interact_t*) interact;
+ int rc = LDAP_SUCCESS;
+
+ if (!ld)
+ return LDAP_PARAM_ERROR;
+
+ while (in->id != SASL_CB_LIST_END) {
+ switch (in->id) {
+ case SASL_CB_NOECHOPROMPT:
+ case SASL_CB_ECHOPROMPT:
+ return LDAP_UNAVAILABLE;
+
+ default:
+ rc = interaction(flags, in, deflts);
+ if (rc)
+ return rc;
+ break;
+ }
+ in++;
+ }
+
+ return rc;
+}
+#endif
+
/*
* Returns 0 upon successful connect, -1 on failure.
*/
@@ -994,11 +1139,12 @@ void autofs_sasl_dispose(struct ldap_conn *conn, struct lookup_context *ctxt)
return;
}
+#ifndef WITH_LDAP_CYRUS_SASL
if (conn && conn->sasl_conn) {
sasl_dispose(&conn->sasl_conn);
conn->sasl_conn = NULL;
}
-
+#endif
if (ctxt->kinit_successful) {
if (--krb5cc_in_use || ctxt->client_cc)
ret = krb5_cc_close(ctxt->krb5ctxt, ctxt->krb5_ccache);
@@ -1099,7 +1245,9 @@ int autofs_sasl_client_init(unsigned logopt)
*/
void autofs_sasl_done(void)
{
+#ifndef WITH_LDAP_CYRUS_SASL
sasl_done();
+#endif
return;
}
diff --git a/modules/lookup_ldap.c b/modules/lookup_ldap.c
index 3e43fc01..d08f648d 100644
--- a/modules/lookup_ldap.c
+++ b/modules/lookup_ldap.c
@@ -223,11 +223,13 @@ int __unbind_ldap_connection(unsigned logopt,
if (ctxt->use_tls == LDAP_TLS_RELEASE)
ctxt->use_tls = LDAP_TLS_INIT;
#ifdef WITH_SASL
+#ifndef WITH_LDAP_CYRUS_SASL
if (ctxt->auth_required & LDAP_NEED_AUTH)
autofs_sasl_unbind(conn, ctxt);
/* No, sasl_dispose does not release the ldap connection
* unless it's using sasl EXTERNAL
*/
+#endif
#endif
if (conn->ldap) {
rv = ldap_unbind_ext(conn->ldap, NULL, NULL);
@@ -574,15 +576,146 @@ static int do_bind(unsigned logopt, struct ldap_conn *conn,
const char *uri, struct lookup_context *ctxt)
{
char *host = NULL, *nhost;
- int rv;
+ int rv, result;
#ifdef WITH_SASL
+#ifdef WITH_LDAP_CYRUS_SASL
+ unsigned int sasl_flags = LDAP_SASL_AUTOMATIC;
+ LDAPMessage *ldap_res = NULL;
+ const char *chosen_mech = NULL;
+ const char *rmech = NULL;
+ char *part_dn = NULL;
+ char *info = NULL;
+ int msgid, err;
+ void *defaults;
+ char *data;
+ ber_len_t *ssf;
+
+#endif
debug(logopt, MODPREFIX "auth_required: %d, sasl_mech %s",
ctxt->auth_required, ctxt->sasl_mech);
if (ctxt->auth_required & LDAP_NEED_AUTH) {
+#ifndef WITH_LDAP_CYRUS_SASL
rv = autofs_sasl_bind(logopt, conn, ctxt);
debug(logopt, MODPREFIX "autofs_sasl_bind returned %d", rv);
+#else
+ if (ctxt->sasl_mech && !strncmp(ctxt->sasl_mech, "GSSAPI", 6)) {
+ rv = sasl_do_kinit(logopt, ctxt);
+ if (rv != 0)
+ return 0;
+ sasl_flags = LDAP_SASL_QUIET;
+ }
+
+ debug(logopt, "Attempting sasl bind with mechanism %s", ctxt->sasl_mech);
+
+ if (ctxt->auth_required & LDAP_AUTH_AUTODETECT) {
+ if (ctxt->sasl_mech) {
+ free(ctxt->sasl_mech);
+ ctxt->sasl_mech = NULL;
+ }
+ }
+
+ /*
+ * If LDAP_AUTH_AUTODETECT is set, it means that there was no
+ * mechanism specified in the configuration file or auto
+ * selection has been requested, so try to auto-select an
+ * auth mechanism.
+ */
+
+ defaults = autofs_ldap_sasl_defaults(conn->ldap, ctxt->sasl_mech, NULL,
+ ctxt->user, ctxt->secret, NULL);
+ do {
+ rv = ldap_sasl_interactive_bind(conn->ldap, NULL,
+ ctxt->sasl_mech, NULL, NULL,
+ sasl_flags,
+ autofs_ldap_sasl_interact,
+ defaults, ldap_res,
+ &rmech, &msgid);
+
+ if (rmech)
+ chosen_mech = rmech;
+
+ if (rv != LDAP_SASL_BIND_IN_PROGRESS)
+ break;
+
+ if (ldap_res) {
+ ldap_msgfree(ldap_res);
+ ldap_res = NULL;
+ }
+
+ if (ldap_result(conn->ldap, msgid, LDAP_MSG_ALL, NULL, &ldap_res) == -1 || !ldap_res) {
+ ldap_get_option(conn->ldap, LDAP_OPT_RESULT_CODE, (void*) &err);
+ ldap_get_option(conn->ldap, LDAP_OPT_DIAGNOSTIC_MESSAGE, (void*) &info);
+ error(logopt, MODPREFIX "ldap_sasl_interactive_bind failed with error %d",
+ err);
+ debug(logopt, "ldap_sasl_interactive_bind: %s", info);
+ ldap_memfree(info);
+ if (ldap_res)
+ ldap_msgfree(ldap_res);
+ return 0;
+ }
+ } while (rv == LDAP_SASL_BIND_IN_PROGRESS);
+
+ autofs_ldap_sasl_freedefs(defaults);
+
+ if (rv != LDAP_SUCCESS) {
+ ldap_get_option(conn->ldap, LDAP_OPT_DIAGNOSTIC_MESSAGE, (void*) &info);
+ error(logopt, MODPREFIX "ldap_sasl_interactive_bind failed with error %d",
+ rv);
+ debug(logopt, "ldap_sasl_interactive_bind: %s", info);
+ ldap_memfree(info);
+ if (ldap_res)
+ ldap_msgfree(ldap_res);
+ return 0;
+ }
+
+ /* Parse the result and check for errors */
+ if (ldap_res) {
+ rv = ldap_parse_result(conn->ldap, ldap_res, &err, &part_dn, &info, NULL, NULL, 0);
+ if (rv != LDAP_SUCCESS) {
+ error(logopt,
+ MODPREFIX "ldap_sasl_interactive_bind parse result failed with error %d",
+ err);
+ debug(logopt, "ldap_sasl_interactive_bind matched DN: %s", part_dn);
+ debug(logopt, "ldap_sasl_interactive_bind parse result: %s", info);
+ ldap_memfree(info);
+ ldap_memfree(part_dn);
+ ldap_msgfree(ldap_res);
+ return 0;
+ }
+ }
+
+ if (info)
+ ldap_memfree(info);
+ if (part_dn)
+ ldap_memfree(part_dn);
+ if (ldap_res)
+ ldap_msgfree(ldap_res);
+
+ /* Conversation was completed successfully by now */
+ result = ldap_get_option(conn->ldap, LDAP_OPT_X_SASL_USERNAME, &data);
+ if (result == LDAP_OPT_SUCCESS && data && *data)
+ debug(logopt, "SASL username: %s", data );
+
+ data = NULL;
+ result = ldap_get_option(conn->ldap, LDAP_OPT_X_SASL_AUTHCID, &data);
+ if (result == LDAP_OPT_SUCCESS && data && *data)
+ debug(logopt, "SASL authcid: %s", data);
+
+ data = NULL;
+ result = ldap_get_option(conn->ldap, LDAP_OPT_X_SASL_AUTHZID, &data);
+ if (result == LDAP_OPT_SUCCESS && data && *data)
+ debug(logopt, "SASL authzid: %s", data);
+
+ ssf = NULL;
+ result = ldap_get_option(conn->ldap, LDAP_OPT_X_SASL_SSF, &ssf);
+ if (result == LDAP_OPT_SUCCESS && ssf)
+ debug(logopt, "SASL SSF: %lu", (unsigned long) ssf);
+
+ debug(logopt, "sasl bind with mechanism %s succeeded",
+ chosen_mech);
+#endif
} else {
rv = bind_ldap_simple(logopt, conn->ldap, uri, ctxt);
debug(logopt, MODPREFIX "ldap simple bind returned %d", rv);
@@ -1793,6 +1926,7 @@ static int do_init(const char *mapfmt,
}
#ifdef WITH_SASL
+#ifndef WITH_LDAP_CYRUS_SASL
/* Init the sasl callbacks */
ldapinit_mutex_lock();
if (!autofs_sasl_client_init(LOGOPT_NONE)) {
@@ -1801,6 +1935,7 @@ static int do_init(const char *mapfmt,
return 1;
}
ldapinit_mutex_unlock();
+#endif
#endif
if (is_amd_format)
