Stop using avc_init() which is deprecated

Stop using avc_init() and use avc_open() instead. With this commit
dbus-daemon will stop using a thread to monitor the avc netlink and will
poll it instead.

https://gitlab.freedesktop.org/dbus/dbus/issues/134

1 files changed, 108 insertions, 111 deletions

diff --git a/bus/selinux.c b/bus/selinux.c
index d09afb4b..c764794c 100644
--- a/bus/selinux.c
+++ b/bus/selinux.c
@@ -49,6 +49,7 @@
 #include <stdarg.h>
 #include <stdio.h>
 #include <grp.h>
+#include <dbus/dbus-watch.h>
 #endif /* HAVE_SELINUX */
 #ifdef HAVE_LIBAUDIT
 #include <libaudit.h>
@@ -64,45 +65,20 @@ static dbus_bool_t selinux_enabled = FALSE;
 /* Store an avc_entry_ref to speed AVC decisions. */
 static struct avc_entry_ref aeref;
 
+/* Store the avc netlink fd. */
+static int avc_netlink_fd = -1;
+
+/* Watch to listen for SELinux status changes via netlink. */
+static DBusWatch *avc_netlink_watch_obj = NULL;
+static DBusLoop *avc_netlink_loop_obj = NULL;
+
 /* Store the SID of the bus itself to use as the default. */
 static security_id_t bus_sid = SECSID_WILD;
 
-/* Thread to listen for SELinux status changes via netlink. */
-static pthread_t avc_notify_thread;
-
 /* Prototypes for AVC callback functions.  */
-static void log_callback (const char *fmt, ...) _DBUS_GNUC_PRINTF (1, 2);
-static void log_audit_callback (void *data, security_class_t class, char *buf, size_t bufleft);
-static void *avc_create_thread (void (*run) (void));
-static void avc_stop_thread (void *thread);
-static void *avc_alloc_lock (void);
-static void avc_get_lock (void *lock);
-static void avc_release_lock (void *lock);
-static void avc_free_lock (void *lock);
-
-/* AVC callback structures for use in avc_init.  */
-static const struct avc_memory_callback mem_cb =
-{
-  .func_malloc = dbus_malloc,
-  .func_free = dbus_free
-};
-static const struct avc_log_callback log_cb =
-{
-  .func_log = log_callback,
-  .func_audit = log_audit_callback
-};
-static const struct avc_thread_callback thread_cb =
-{
-  .func_create_thread = avc_create_thread,
-  .func_stop_thread = avc_stop_thread
-};
-static const struct avc_lock_callback lock_cb =
-{
-  .func_alloc_lock = avc_alloc_lock,
-  .func_get_lock = avc_get_lock,
-  .func_release_lock = avc_release_lock,
-  .func_free_lock = avc_free_lock
-};
+static int log_callback (int type, const char *fmt, ...) _DBUS_GNUC_PRINTF (2, 3);
+static int log_audit_callback (void *data, security_class_t class, char *buf, size_t bufleft);
+
 #endif /* HAVE_SELINUX */
 
 /**
@@ -115,8 +91,8 @@ static const struct avc_lock_callback lock_cb =
  */
 #ifdef HAVE_SELINUX
 
-static void 
-log_callback (const char *fmt, ...) 
+static int
+log_callback (int type, const char *fmt, ...)
 {
   va_list ap;
 #ifdef HAVE_LIBAUDIT
@@ -150,6 +126,8 @@ log_callback (const char *fmt, ...)
 out:
 #endif
   va_end(ap);
+
+  return 0;
 }
 
 /**
@@ -170,7 +148,7 @@ policy_reload_callback (u_int32_t event, security_id_t ssid,
 /**
  * Log any auxiliary data 
  */
-static void
+static int
 log_audit_callback (void *data, security_class_t class, char *buf, size_t bufleft)
 {
   DBusString *audmsg = data;
@@ -188,73 +166,20 @@ log_audit_callback (void *data, security_class_t class, char *buf, size_t buflef
       if (bufleft > (size_t) _dbus_string_get_length(&s))
         _dbus_string_copy_to_buffer_with_nul (&s, buf, bufleft);
     }
-}
-
-/**
- * Create thread to notify the AVC of enforcing and policy reload
- * changes via netlink.
- *
- * @param run the thread run function
- * @return pointer to the thread
- */
-static void *
-avc_create_thread (void (*run) (void))
-{
-  int rc;
-
-  rc = pthread_create (&avc_notify_thread, NULL, (void *(*) (void *)) run, NULL);
-  if (rc != 0)
-    {
-      _dbus_warn ("Failed to start AVC thread: %s", _dbus_strerror (rc));
-      exit (1);
-    }
-  return &avc_notify_thread;
-}
 
-/* Stop AVC netlink thread.  */
-static void
-avc_stop_thread (void *thread)
-{
-  pthread_cancel (*(pthread_t *) thread);
+  return 0;
 }
 
-/* Allocate a new AVC lock.  */
-static void *
-avc_alloc_lock (void)
+static dbus_bool_t
+handle_avc_netlink_watch (DBusWatch *passed_watch, unsigned int flags, void *data)
 {
-  pthread_mutex_t *avc_mutex;
-
-  avc_mutex = dbus_new (pthread_mutex_t, 1);
-  if (avc_mutex == NULL)
+  if (avc_netlink_check_nb () < 0)
     {
-      _dbus_warn ("Could not create mutex: %s", _dbus_strerror (errno));
-      exit (1);
+      _dbus_warn ("Failed to check the netlink socket for pending messages and process them: %s", _dbus_strerror (errno));
+      return FALSE;
     }
-  pthread_mutex_init (avc_mutex, NULL);
-
-  return avc_mutex;
-}
-
-/* Acquire an AVC lock.  */
-static void
-avc_get_lock (void *lock)
-{
-  pthread_mutex_lock (lock);
-}
 
-/* Release an AVC lock.  */
-static void
-avc_release_lock (void *lock)
-{
-  pthread_mutex_unlock (lock);
-}
-
-/* Free an AVC lock.  */
-static void
-avc_free_lock (void *lock)
-{
-  pthread_mutex_destroy (lock);
-  dbus_free (lock);
+  return TRUE;
 }
 #endif /* HAVE_SELINUX */
 
@@ -335,7 +260,7 @@ static struct security_class_mapping dbus_map[] = {
  * logging callbacks.
  */
 dbus_bool_t
-bus_selinux_full_init (void)
+bus_selinux_full_init (BusContext *context, DBusError *error)
 {
 #ifdef HAVE_SELINUX
   char *bus_context;
@@ -358,9 +283,11 @@ bus_selinux_full_init (void)
     }
 
   avc_entry_ref_init (&aeref);
-  if (avc_init ("avc", &mem_cb, &log_cb, &thread_cb, &lock_cb) < 0)
+  if (avc_open (NULL, 0) < 0)
     {
-      _dbus_warn ("Failed to start Access Vector Cache (AVC).");
+      dbus_set_error (error, DBUS_ERROR_FAILED,
+                      "Failed to start Access Vector Cache (AVC): %s",
+                      _dbus_strerror (errno));
       return FALSE;
     }
   else
@@ -368,34 +295,90 @@ bus_selinux_full_init (void)
       _dbus_verbose ("Access Vector Cache (AVC) started.\n");
     }
 
+  avc_netlink_fd = avc_netlink_acquire_fd ();
+  if (avc_netlink_fd < 0)
+    {
+       dbus_set_error (error, DBUS_ERROR_FAILED,
+                      "Cannot acquire AVC netlink fd: %s",
+                      _dbus_strerror (errno));
+       goto error;
+    }
+
+  _dbus_fd_set_close_on_exec (avc_netlink_fd);
+
+  avc_netlink_loop_obj = bus_context_get_loop (context);
+  /* avc_netlink_loop_obj is a global variable */
+  _dbus_loop_ref (avc_netlink_loop_obj);
+
+  avc_netlink_watch_obj = _dbus_watch_new (avc_netlink_fd, DBUS_WATCH_READABLE, TRUE,
+                                           handle_avc_netlink_watch, NULL, NULL);
+  if (avc_netlink_watch_obj == NULL)
+    {
+      BUS_SET_OOM (error);
+      goto error;
+    }
+
+  if (!_dbus_loop_add_watch (avc_netlink_loop_obj, avc_netlink_watch_obj))
+    {
+      _dbus_watch_invalidate (avc_netlink_watch_obj);
+      _dbus_clear_watch (&avc_netlink_watch_obj);
+      avc_netlink_watch_obj = NULL;
+      BUS_SET_OOM (error);
+      goto error;
+    }
+
   if (avc_add_callback (policy_reload_callback, AVC_CALLBACK_RESET,
                        NULL, NULL, 0, 0) < 0)
     {
-      _dbus_warn ("Failed to add policy reload callback: %s",
-                  _dbus_strerror (errno));
-      avc_destroy ();
-      return FALSE;
+      dbus_set_error (error, DBUS_ERROR_FAILED,
+                      "Failed to add policy reload callback: %s",
+                      _dbus_strerror (errno));
+      goto error;
     }
 
+  selinux_set_callback (SELINUX_CB_AUDIT, (union selinux_callback) log_audit_callback);
+  selinux_set_callback (SELINUX_CB_LOG, (union selinux_callback) log_callback);
+
   bus_context = NULL;
   bus_sid = SECSID_WILD;
 
   if (getcon (&bus_context) < 0)
     {
-      _dbus_verbose ("Error getting context of bus: %s\n",
-                     _dbus_strerror (errno));
-      return FALSE;
+      dbus_set_error (error, DBUS_ERROR_FAILED,
+                      "Error getting context of bus: %s",
+                      _dbus_strerror (errno));
+      goto error;
     }
       
   if (avc_context_to_sid (bus_context, &bus_sid) < 0)
     {
-      _dbus_verbose ("Error getting SID from bus context: %s\n",
-                     _dbus_strerror (errno));
+      dbus_set_error (error, DBUS_ERROR_FAILED,
+                      "Error getting SID from bus context: %s",
+                      _dbus_strerror (errno));
       freecon (bus_context);
-      return FALSE;
+      goto error;
     }
 
   freecon (bus_context);
+
+  return TRUE;
+
+error:
+  if (avc_netlink_watch_obj)
+    {
+      _dbus_loop_remove_watch (avc_netlink_loop_obj, avc_netlink_watch_obj);
+      _dbus_watch_invalidate (avc_netlink_watch_obj);
+      _dbus_clear_watch (&avc_netlink_watch_obj);
+    }
+  _dbus_clear_loop (&avc_netlink_loop_obj);
+  if (avc_netlink_fd >= 0)
+    {
+      avc_netlink_release_fd ();
+      avc_netlink_fd = -1;
+    }
+  avc_destroy ();
+  _DBUS_ASSERT_ERROR_IS_SET (error);
+  return FALSE;
   
 #endif /* HAVE_SELINUX */
   return TRUE;
@@ -976,6 +959,20 @@ bus_selinux_shutdown (void)
 
   _dbus_verbose ("AVC shutdown\n");
 
+  if (avc_netlink_watch_obj)
+    {
+      _dbus_loop_remove_watch (avc_netlink_loop_obj, avc_netlink_watch_obj);
+      _dbus_watch_invalidate (avc_netlink_watch_obj);
+      _dbus_clear_watch (&avc_netlink_watch_obj);
+    }
+  _dbus_clear_loop (&avc_netlink_loop_obj);
+
+  if (avc_netlink_fd >= 0)
+    {
+      avc_netlink_release_fd ();
+      avc_netlink_fd = -1;
+    }
+
   if (bus_sid != SECSID_WILD)
     {
       bus_sid = SECSID_WILD;