s4:kdc Push context to hdb_samba4 by way of the 'name' of the DB

This overloads the 'name' part of the keytab name to supply a context
pointer, and so avoids 3 global variables!

To do this, we had to stop putting the entry for kpasswd into the
secrets.ldb.  (I don't consider this a big loss, and any entry left
there by an upgrade will be harmless).

Andrew Bartlett

source4/kdc/hdb-samba4.c

@@ -1563,8 +1563,14 @@ NTSTATUS hdb_samba4_create_kdc(TALLOC_CTX *mem_ctx,
 static krb5_error_code hdb_samba4_create(krb5_context context, struct HDB **db, const char *arg)
 {
 	NTSTATUS nt_status;
+	void *ptr;
+	struct hdb_samba4_context *hdb_samba4_context;
+	if (sscanf(arg, "&%p", &ptr) != 1) {
+		return EINVAL;
+	}
+	hdb_samba4_context = talloc_get_type_abort(ptr, struct hdb_samba4_context);
 	/* The global kdc_mem_ctx and kdc_lp_ctx, Disgusting, ugly hack, but it means one less private hook */
-	nt_status = hdb_samba4_create_kdc(hdb_samba4_mem_ctx, hdb_samba4_ev_ctx, hdb_samba4_lp_ctx,
+	nt_status = hdb_samba4_create_kdc(hdb_samba4_context, hdb_samba4_context->ev_ctx, hdb_samba4_context->lp_ctx,
 					  context, db);
 
 	if (NT_STATUS_IS_OK(nt_status)) {
@@ -1574,9 +1580,12 @@ static krb5_error_code hdb_samba4_create(krb5_context context, struct HDB **db,
 }
 
 /* Only used in the hdb-backed keytab code
- * for a keytab of 'samba4:', to find
+ * for a keytab of 'samba4&<address>', to find
  * kpasswd's key in the main DB, and to
- * copy all the keys into a file (libnet_keytab_export) */
+ * copy all the keys into a file (libnet_keytab_export)
+ *
+ * The <address> is the string form of a pointer to a talloced struct hdb_samba_context
+ */
 struct hdb_method hdb_samba4 = {
 	.interface_version = HDB_INTERFACE_VERSION,
 	.prefix = "samba4", 

source4/kdc/hdb-samba4.h

@@ -21,8 +21,12 @@
 */
 
 extern TALLOC_CTX *hdb_samba4_mem_ctx;
-extern struct tevent_context *hdb_samba4_ev_ctx;
+
-extern struct loadparm_context *hdb_samba4_lp_ctx;
+struct hdb_samba4_context {
+	struct tevent_context *ev_ctx;
+	struct loadparm_context *lp_ctx;
+};
+
 extern struct hdb_method hdb_samba4;
 
 struct hdb_samba4_private {

source4/kdc/kdc.c

@@ -729,15 +729,20 @@ static void kdc_task_init(struct task_server *task)
 				       kdc->smb_krb5_context->krb5_context, 
 				       &kdc->config->db[0]);
 	if (!NT_STATUS_IS_OK(status)) {
-		task_server_terminate(task, "kdc: hdb_ldb_create (setup KDC database) failed");
+		task_server_terminate(task, "kdc: hdb_samba4_create_kdc (setup KDC database) failed");
 		return; 
 	}
 
-	/* Register hdb-samba4 hooks */
+	/* Register hdb-samba4 hooks for use as a keytab */
 
-	hdb_samba4_mem_ctx = kdc->smb_krb5_context;
+	kdc->hdb_samba4_context = talloc(kdc, struct hdb_samba4_context);
-	hdb_samba4_ev_ctx = task->event_ctx;
+	if (!kdc->hdb_samba4_context) {
-	hdb_samba4_lp_ctx = task->lp_ctx;
+		task_server_terminate(task, "kdc: out of memory");
+		return; 
+	}
+
+	kdc->hdb_samba4_context->ev_ctx = task->event_ctx;
+	kdc->hdb_samba4_context->lp_ctx = task->lp_ctx;
 
 	ret = krb5_plugin_register(kdc->smb_krb5_context->krb5_context, 
 				   PLUGIN_TYPE_DATA, "hdb",

source4/kdc/kdc.h

@@ -47,6 +47,7 @@ struct kdc_server {
 	struct task_server *task;
 	krb5_kdc_configuration *config;
 	struct smb_krb5_context *smb_krb5_context;
+	struct hdb_samba4_context *hdb_samba4_context;
 };
 
 

source4/kdc/kpasswdd.c

@@ -448,6 +448,8 @@ bool kpasswdd_process(struct kdc_server *kdc,
 	struct gensec_security *gensec_security;
 	TALLOC_CTX *tmp_ctx = talloc_new(mem_ctx);
 
+	char *keytab_name;
+
 	if (!tmp_ctx) {
 		return false;
 	}
@@ -489,8 +491,12 @@ bool kpasswdd_process(struct kdc_server *kdc,
 	 * we already have, rather than a new context */	
 	cli_credentials_set_krb5_context(server_credentials, kdc->smb_krb5_context);
 	cli_credentials_set_conf(server_credentials, kdc->task->lp_ctx);
-	nt_status = cli_credentials_set_stored_principal(server_credentials, kdc->task->event_ctx, kdc->task->lp_ctx, "kadmin/changepw");
+
-	if (!NT_STATUS_IS_OK(nt_status)) {
+	keytab_name = talloc_asprintf(server_credentials, "HDB:samba4&%p", kdc->hdb_samba4_context);
+
+	cli_credentials_set_username(server_credentials, "kadmin/changepw", CRED_SPECIFIED);
+	ret = cli_credentials_set_keytab_name(server_credentials, kdc->task->event_ctx, kdc->task->lp_ctx, keytab_name, CRED_SPECIFIED);
+	if (ret != 0) {
 		ret = kpasswdd_make_unauth_error_reply(kdc, mem_ctx, 
 						       KRB5_KPASSWD_HARDERROR,
 						       talloc_asprintf(mem_ctx, 

source4/setup/secrets_dc.ldif

@@ -11,22 +11,7 @@ msDS-KeyVersionNumber: 1
 objectSid: ${DOMAINSID}
 privateKeytab: ${SECRETS_KEYTAB}
 
-# A hook from our credentials system into HDB, as we must be on a KDC,
+#Update a keytab for the external DNS server to use 
-# we can look directly into the database.
-dn: samAccountName=krbtgt,flatname=${DOMAIN},CN=Principals
-objectClass: top
-objectClass: secret
-objectClass: kerberosSecret
-flatname: ${DOMAIN}
-realm: ${REALM}
-sAMAccountName: krbtgt
-objectSid: ${DOMAINSID}
-servicePrincipalName: kadmin/changepw
-krb5Keytab: HDB:samba4:${SAM_LDB}:
-#The trailing : here is a HACK, but it matches the Heimdal format. 
-
-# A hook from our credentials system into HDB, as we must be on a KDC,
-# we can look directly into the database.
 dn: servicePrincipalName=DNS/${DNSDOMAIN},CN=Principals
 objectClass: top
 objectClass: secret