policy-default: Use libsmack to check client label

Use the client file descriptor to find out the SMACK label of that
client.  Enforces homescreen to bind to agl_shell and launcher and
alexa-viewer to bind to the agl-shell-desktop interface. Allows access
to agl_shell_desktop to tbtnavi and hvac as those contain example code
on use it for moving it to other outputs.

Bug-AGL: SPEC-3396

Signed-off-by: Marius Vlad <marius.vlad@collabora.com>
Change-Id: I1a1abf2d2786624ffa484b6577de17f5010d5ac6

2 files changed, 54 insertions, 0 deletions

diff --git a/meson.build b/meson.build
index bc65c1c..ad996e8 100644
--- a/meson.build
+++ b/meson.build
@@ -41,6 +41,7 @@ foreach func: optional_libc_funcs
 endforeach
 
 dep_libsystemd = dependency('libsystemd', required: false)
+dep_libsmack = dependency('libsmack', required: false)
 dep_scanner = dependency('wayland-scanner', native: true)
 prog_scanner = find_program(dep_scanner.get_pkgconfig_variable('wayland_scanner'))
 dep_wp = dependency('wayland-protocols', version: '>= 1.18')
@@ -180,6 +181,11 @@ if deps_remoting.length() == depnames.length()
   message('Found remoting depends, enabling remoting')
 endif
 
+if dep_libsmack.found()
+  config_h.set('HAVE_SMACK', 1)
+  deps_libweston += dep_libsmack
+endif
+
 configure_file(output: 'config.h', configuration: config_h)
 
 exe_agl_compositor = executable(
diff --git a/src/policy-default.c b/src/policy-default.c
index 23842ab..a09bb1a 100644
--- a/src/policy-default.c
+++ b/src/policy-default.c
@@ -26,6 +26,12 @@
 #include "ivi-compositor.h"
 #include "policy.h"
 
+#ifdef HAVE_SMACK
+#include <sys/smack.h>
+#endif
+
+#include <string.h>
+
 /*
  * default policy implementation allows every action to be possible
  *
@@ -78,11 +84,52 @@ ivi_policy_default_surface_advertise_state_change(struct ivi_surface *surf, void
 	return true;
 }
 
+#ifdef HAVE_SMACK
+static bool
+ivi_policy_default_shell_bind_interface(void *client, void *interface)
+{
+	struct wl_interface *shell_interface = interface;
+	struct wl_client *conn_client = client;
+
+	pid_t pid, uid, gid;
+	int client_fd;
+	char *label;
+	bool ret = false;
+
+	wl_client_get_credentials(conn_client, &pid, &uid, &gid);
+
+	client_fd = wl_client_get_fd(conn_client);
+	if (smack_new_label_from_socket(client_fd, &label) < 0) {
+		return ret;
+	}
+
+	if (strcmp(shell_interface->name, "agl_shell") == 0)
+		if (strcmp(label, "User::App::homescreen") == 0)
+			ret = true;
+
+	if (strcmp(shell_interface->name, "agl_shell_desktop") == 0)
+		if (strcmp(label, "User::App::launcher") == 0 ||
+		    strcmp(label, "User::App::alexa-viewer") == 0 ||
+		    strcmp(label, "User::App::tbtnavi") == 0 ||
+		    strcmp(label, "User::App::hvac") == 0)
+			ret = true;
+
+	if (ret)
+		weston_log("Client with pid %d, uid %d, gid %d, allowed "
+				"to bind to %s for label %s\n", pid, uid, gid,
+				shell_interface->name, label);
+
+	/* client responsible for free'ing */
+	free(label);
+	return ret;
+}
+#else
 static bool
 ivi_policy_default_shell_bind_interface(void *client, void *interface)
 {
 	return true;
 }
+#endif
 
 static bool
 ivi_policy_default_allow_to_add(void *user_data)
@@ -131,5 +178,6 @@ ivi_policy_init(struct ivi_compositor *ivi)
 	if (!ivi->policy)
 		return -1;
 
+	weston_log("Installing 'allow-all' policy engine\n");
 	return 0;
 }