SELinux: Enable dynamic enable/disable of the network access checks

This patch introduces a mechanism for checking when labeled IPsec or SECMARK
are in use by keeping introducing a configuration reference counter for each
subsystem.  In the case of labeled IPsec, whenever a labeled SA or SPD entry
is created the labeled IPsec/XFRM reference count is increased and when the
entry is removed it is decreased.  In the case of SECMARK, when a SECMARK
target is created the reference count is increased and later decreased when the
target is removed.  These reference counters allow SELinux to quickly determine
if either of these subsystems are enabled.

NetLabel already has a similar mechanism which provides the netlbl_enabled()
function.

This patch also renames the selinux_relabel_packet_permission() function to
selinux_secmark_relabel_packet_permission() as the original name and
description were misleading in that they referenced a single packet label which
is not the case.

Signed-off-by: Paul Moore <paul.moore@hp.com>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 18 insertions, 2 deletions

diff --git a/security/selinux/exports.c b/security/selinux/exports.c
index b6f9694..87d2bb3 100644
--- a/security/selinux/exports.c
+++ b/security/selinux/exports.c
@@ -17,10 +17,14 @@
 #include <linux/selinux.h>
 #include <linux/fs.h>
 #include <linux/ipc.h>
+#include <asm/atomic.h>
 
 #include "security.h"
 #include "objsec.h"
 
+/* SECMARK reference count */
+extern atomic_t selinux_secmark_refcount;
+
 int selinux_sid_to_string(u32 sid, char **ctx, u32 *ctxlen)
 {
 	if (selinux_enabled)
@@ -74,7 +78,7 @@ int selinux_string_to_sid(char *str, u32 *sid)
 }
 EXPORT_SYMBOL_GPL(selinux_string_to_sid);
 
-int selinux_relabel_packet_permission(u32 sid)
+int selinux_secmark_relabel_packet_permission(u32 sid)
 {
 	if (selinux_enabled) {
 		struct task_security_struct *tsec = current->security;
@@ -84,4 +88,16 @@ int selinux_relabel_packet_permission(u32 sid)
 	}
 	return 0;
 }
-EXPORT_SYMBOL_GPL(selinux_relabel_packet_permission);
+EXPORT_SYMBOL_GPL(selinux_secmark_relabel_packet_permission);
+
+void selinux_secmark_refcount_inc(void)
+{
+	atomic_inc(&selinux_secmark_refcount);
+}
+EXPORT_SYMBOL_GPL(selinux_secmark_refcount_inc);
+
+void selinux_secmark_refcount_dec(void)
+{
+	atomic_dec(&selinux_secmark_refcount);
+}
+EXPORT_SYMBOL_GPL(selinux_secmark_refcount_dec);