selinux: reduce the number of calls to synchronize_net() when flushing caches

When flushing the AVC, such as during a policy load, the various
network caches are also flushed, with each making a call to
synchronize_net() which has shown to be expensive in some cases.
This patch consolidates the network cache flushes into a single AVC
callback which only calls synchronize_net() once for each AVC cache
flush.

Reported-by: Jaejyn Shin <flagon22bass@gmail.com>
Signed-off-by: Paul Moore <pmoore@redhat.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 336f0a04450e..39bc8c94b969 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -161,6 +161,17 @@ static int selinux_peerlbl_enabled(void)
         return (selinux_policycap_alwaysnetwork || netlbl_enabled() || selinux_xfrm_enabled());
 }
 
+static int selinux_netcache_avc_callback(u32 event)
+{
+        if (event == AVC_CALLBACK_RESET) {
+                sel_netif_flush();
+                sel_netnode_flush();
+                sel_netport_flush();
+                synchronize_net();
+        }
+        return 0;
+}
+
 /*
  * initialise the security for the init task
  */
@@ -5993,6 +6004,9 @@ static __init int selinux_init(void)
         if (register_security(&selinux_ops))
                 panic("SELinux: Unable to register with kernel.\n");
 
+        if (avc_add_callback(selinux_netcache_avc_callback, AVC_CALLBACK_RESET))
+                panic("SELinux: Unable to register AVC netcache callback\n");
+
         if (selinux_enforcing)
                 printk(KERN_DEBUG "SELinux:  Starting in enforcing mode\n");
         else