Support initrc_t generated pid files with file transition

For some daemons, it is the init script that is responsible for creating
the PID file of the daemon. As we do not want to update the init SELinux
policy module for each of these situations, we need to introduce an
interface that can be called by the SELinux policy module of the caller
(the daemon domain).

The initial suggestion was to transform the init_daemon_run_dir
interface, which offers a similar approach for directories in /run, into
a class-agnostic interface. Several names have been suggested, such as
init_script_spec_run_content or init_script_generic_run_filetrans_spec,
but in the end init_daemon_pid_file was used.

The interface requires the class(es) on which the file transition should
occur, like so:

  init_daemon_pid_file(xdm_var_run_t, dir, "xdm")
  init_daemon_pid_file(postgresql_var_run_t, file, "postgresql.pid")

Signed-off-by: Sven Vermeulen <sven.vermeulen@siphos.be>

policy/modules/system/init.if

@@ -410,6 +410,39 @@ interface(`init_ranged_system_domain',`
 	')
 ')
 
+########################################
+## <summary>
+##	Mark the file type as a daemon pid file, allowing initrc_t
+##	to create it
+## </summary>
+## <param name="filetype">
+##	<summary>
+##	Type to mark as a daemon pid file
+##	</summary>
+## </param>
+## <param name="class">
+##	<summary>
+##	Class on which the type is applied
+##	</summary>
+## </param>
+## <param name="filename">
+##	<summary>
+##	Filename of the file that the init script creates
+##	</summary>
+## </param>
+#
+interface(`init_daemon_pid_file',`
+	gen_require(`
+		attribute daemonpidfile;
+		type initrc_t;
+	')
+
+	typeattribute $1 daemonpidfile;
+
+	files_pid_file($1)
+	files_pid_filetrans(initrc_t, $1, $2, $3)
+')
+
 ########################################
 ## <summary>
 ##	Mark the file type as a daemon run dir, allowing initrc_t

policy/modules/system/init.te

@@ -23,6 +23,8 @@ attribute init_run_all_scripts_domain;
 # Mark process types as daemons
 attribute daemon;
 
+# Mark file type as a daemon pid file
+attribute daemonpidfile;
 # Mark file type as a daemon run directory
 attribute daemonrundir;
 
@@ -251,6 +253,10 @@ init_telinit(initrc_t)
 
 can_exec(initrc_t, init_script_file_type)
 
+create_dirs_pattern(initrc_t, daemonpidfile, daemonpidfile)
+manage_files_pattern(initrc_t, daemonpidfile, daemonpidfile)
+setattr_dirs_pattern(initrc_t, daemonpidfile, daemonpidfile)
+
 create_dirs_pattern(initrc_t, daemonrundir, daemonrundir)
 setattr_dirs_pattern(initrc_t, daemonrundir, daemonrundir)