s3:lib: Introduce cmdline context wrapper

Command line tools need acccess to the same messaging context provided
by server_messaging_context, as common code for db_open uses that
context. We want to have additional checking for command line tools
without having that code part of the servers. Introduce a wrapper
library to use for command line tools with the additional checks, that
then acquires the server_messaging_context.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=13465

Signed-off-by: Christof Schmitt <cs@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
(cherry picked from commit 8c3b62e6231e62feafacf2a7ee4c9d41cd27a4a1)

3 files changed, 102 insertions, 0 deletions

diff --git a/source3/lib/cmdline_contexts.c b/source3/lib/cmdline_contexts.c
new file mode 100644
index 00000000000..5713f7f7956
--- /dev/null
+++ b/source3/lib/cmdline_contexts.c
@@ -0,0 +1,70 @@
+/*
+   Unix SMB/CIFS implementation.
+   cmdline context wrapper.
+
+   Copyright (C) Christof Schmitt <cs@samba.org> 2018
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "cmdline_contexts.h"
+#include "includes.h"
+#include "messages.h"
+
+struct messaging_context *cmdline_messaging_context(const char *config_file)
+{
+	struct messaging_context *msg_ctx = NULL;
+
+	/*
+	 * Ensure that a config is loaded, in case the underlying
+	 * messaging_init needs to create directories or sockets.
+	 */
+	if (!lp_loaded()) {
+		if (!lp_load_initial_only(config_file)) {
+			return NULL;
+		}
+	}
+
+	/*
+	 * Clustered Samba can only work as root due to required
+	 * access to the registry and ctdb, which in turn requires
+	 * messaging access as root.
+	 */
+	if (lp_clustering() && geteuid() != 0) {
+		fprintf(stderr, "Cluster mode requires running as root.\n");
+		exit(1);
+	}
+
+	msg_ctx = server_messaging_context();
+	if (msg_ctx == NULL) {
+		if (geteuid() == 0) {
+			fprintf(stderr,
+				"Unable to initialize messaging context!\n");
+			exit(1);
+		} else {
+			/*
+			 * Non-cluster, non-root: Log error, but leave
+			 * it up to the caller how to proceed.
+			 */
+			DBG_NOTICE("Unable to initialize messaging context.\n");
+		}
+	}
+
+	return msg_ctx;
+}
+
+void cmdline_messaging_context_free(void)
+{
+	server_messaging_context_free();
+}
diff --git a/source3/lib/cmdline_contexts.h b/source3/lib/cmdline_contexts.h
new file mode 100644
index 00000000000..21f81f0f1cd
--- /dev/null
+++ b/source3/lib/cmdline_contexts.h
@@ -0,0 +1,27 @@
+/*
+   Unix SMB/CIFS implementation.
+   cmdline context wrapper.
+
+   Copyright (C) Christof Schmitt <cs@samba.org> 2018
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef _LIB_CMDLINE_CONTEXTS_H
+#define _LIB_CMDLINE_CONTEXTS_H
+
+struct messaging_context *cmdline_messaging_context(const char *config_file);
+void cmdline_messaging_context_free(void);
+
+#endif
diff --git a/source3/wscript_build b/source3/wscript_build
index 83ef56d8ba8..1808b5e0cb3 100644
--- a/source3/wscript_build
+++ b/source3/wscript_build
@@ -270,6 +270,11 @@ bld.SAMBA3_LIBRARY('util_cmdline',
                    deps='secrets3',
                    private_library=True)
 
+bld.SAMBA3_LIBRARY('cmdline_contexts',
+                   source='lib/cmdline_contexts.c',
+                   deps='samba3core',
+                   private_library=True)
+
 bld.SAMBA3_SUBSYSTEM('KRBCLIENT',
                      source='libads/kerberos.c libads/ads_status.c',
                      public_deps='krb5samba asn1util k5crypto gssapi LIBTSOCKET CLDAP LIBNMB')