Declare a module service "kernel_mac_support" when MAC support is

enabled and the kernel provides the MAC registration and entry point
service.  Declare a dependency on that module service for any
MAC module registered using mac_policy.h.  For now, hard code the
version as 1, but once we've come up with a versioning policy, we'll
move to a #define of some sort.  In the mean time, this will prevent
loading a MAC module when 'options MAC' isn't present, which (due to
a bug in the kernel linker) can result if the MAC module is preloaded
via loader.conf.

This particular evil recommended by:	peter
Obtained from:	TrustedBSD Project
Sponsored by:	DARPA, NAI LAbs

1 files changed, 8 insertions, 0 deletions

diff --git a/sys/kern/kern_mac.c b/sys/kern/kern_mac.c
index 6544f01ae5d0..547647caa7bf 100644
--- a/sys/kern/kern_mac.c
+++ b/sys/kern/kern_mac.c
@@ -54,6 +54,7 @@
 #include <sys/mutex.h>
 #include <sys/sx.h>
 #include <sys/mac.h>
+#include <sys/module.h>
 #include <sys/proc.h>
 #include <sys/systm.h>
 #include <sys/sysproto.h>
@@ -87,6 +88,13 @@
 
 #ifdef MAC
 
+/*
+ * Declare that the kernel provides MAC support, version 1.  This permits
+ * modules to refuse to be loaded if the necessary support isn't present,
+ * even if it's pre-boot.
+ */
+MODULE_VERSION(kernel_mac_support, 1);
+
 SYSCTL_DECL(_security);
 
 SYSCTL_NODE(_security, OID_AUTO, mac, CTLFLAG_RW, 0,