From 8f31796268fb52b8ac05ed3600bedd715021d055 Mon Sep 17 00:00:00 2001
From: Jacek Bukarewicz <j.bukarewicz@samsung.com>
Date: Tue, 23 Jun 2015 11:08:48 +0200
Subject: [PATCH] Perform Cynara runtime policy checks by default

This change introduces http://tizen.org/privilege/internal/dbus privilege
which is supposed to be available only to trusted system resources.
Checks for this privilege are used in place of certain allow rules to
make security policy more strict.

For system bus sending and receiving signals now requires
http://tizen.org/privilege/internal/dbus privilege. Requesting name
ownership and sending methods is still denied by default.

For session bus http://tizen.org/privilege/internal/dbus privilege
is now required for requesting name, calling methods, sending and receiving
signals.

Services are supposed to override these default settings to implement their
own security policy.

Change-Id: Ifb4a160bf6e0638404e0295a2e4fa3077efd881c
Signed-off-by: Jacek Bukarewicz <j.bukarewicz@samsung.com>
---
 bus/session.conf.in | 32 ++++++++++++++++++++++++++------
 bus/system.conf.in  | 23 ++++++++++++++++++-----
 2 files changed, 44 insertions(+), 11 deletions(-)

diff --git a/bus/session.conf.in b/bus/session.conf.in
index affa7f1..157dfb4 100644
--- a/bus/session.conf.in
+++ b/bus/session.conf.in
@@ -27,12 +27,32 @@
   <standard_session_servicedirs />
 
   <policy context="default">
-    <!-- Allow everything to be sent -->
-    <allow send_destination="*" eavesdrop="true"/>
-    <!-- Allow everything to be received -->
-    <allow eavesdrop="true"/>
-    <!-- Allow anyone to own anything -->
-    <allow own="*"/>
+    <!-- By default clients require internal/dbus privilege to communicate
+         with D-Bus services and to claim name ownership. This is internal privilege that
+         is only accessible to trusted system services -->
+    <check own="*"                  privilege="http://tizen.org/privilege/internal/dbus" />
+    <check send_type="method_call"  privilege="http://tizen.org/privilege/internal/dbus" />
+    <check send_type="signal"       privilege="http://tizen.org/privilege/internal/dbus" />
+    <check receive_type="signal"    privilege="http://tizen.org/privilege/internal/dbus" />
+
+    <!-- Reply messages (method returns, errors) are allowed
+         by default -->
+    <allow send_requested_reply="true" send_type="method_return"/>
+    <allow send_requested_reply="true" send_type="error"/>
+
+    <!-- All messages but signals may be received by default -->
+    <allow receive_type="method_call"/>
+    <allow receive_type="method_return"/>
+    <allow receive_type="error"/>
+
+    <!-- Allow anyone to talk to the message bus -->
+    <allow send_destination="org.freedesktop.DBus"/>
+    <allow receive_sender="org.freedesktop.DBus"/>
+
+    <!-- But disallow some specific bus services -->
+    <deny send_destination="org.freedesktop.DBus"
+          send_interface="org.freedesktop.DBus"
+          send_member="UpdateActivationEnvironment"/>
   </policy>
 
   <!-- Include legacy configuration location -->
diff --git a/bus/system.conf.in b/bus/system.conf.in
index 014f67e..4f89605 100644
--- a/bus/system.conf.in
+++ b/bus/system.conf.in
@@ -50,24 +50,37 @@
     <deny own="*"/>
     <deny send_type="method_call"/>
 
-    <!-- Signals and reply messages (method returns, errors) are allowed
+    <!-- By default clients require internal/dbus privilege to send and receive signaks.
+         This is internal privilege that is only accessible to trusted system services -->
+    <check send_type="signal"       privilege="http://tizen.org/privilege/internal/dbus" />
+    <check receive_type="signal"    privilege="http://tizen.org/privilege/internal/dbus" />
+
+    <!-- Reply messages (method returns, errors) are allowed
          by default -->
-    <allow send_type="signal"/>
     <allow send_requested_reply="true" send_type="method_return"/>
     <allow send_requested_reply="true" send_type="error"/>
 
-    <!-- All messages may be received by default -->
+    <!-- All messages but signals may be received by default -->
     <allow receive_type="method_call"/>
     <allow receive_type="method_return"/>
     <allow receive_type="error"/>
-    <allow receive_type="signal"/>
 
     <!-- Allow anyone to talk to the message bus -->
     <allow send_destination="org.freedesktop.DBus"
            send_interface="org.freedesktop.DBus" />
     <allow send_destination="org.freedesktop.DBus"
            send_interface="org.freedesktop.DBus.Introspectable"/>
-    <!-- But disallow some specific bus services -->
+
+    <!-- If there is a need specific bus services could be protected by Cynara as well.
+         However, this can lead to deadlock during the boot process when such check is made and
+         Cynara is not yet activated (systemd calls protected method synchronously,
+         dbus daemon tries to consult Cynara, Cynara waits for systemd activation).
+         Therefore it is advised to allow root processes to use bus services.
+         Currently anyone is allowed to talk to the message bus -->
+    <allow send_destination="org.freedesktop.DBus"/>
+    <allow receive_sender="org.freedesktop.DBus"/>
+
+    <!-- Disallow some specific bus services -->
     <deny send_destination="org.freedesktop.DBus"
           send_interface="org.freedesktop.DBus"
           send_member="UpdateActivationEnvironment"/>
-- 
2.7.4