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, 16 insertions, 2 deletions

diff --git a/security/selinux/xfrm.c b/security/selinux/xfrm.c
index e0760396903..7e158205d08 100644
--- a/security/selinux/xfrm.c
+++ b/security/selinux/xfrm.c
@@ -46,11 +46,14 @@
 #include <net/checksum.h>
 #include <net/udp.h>
 #include <asm/semaphore.h>
+#include <asm/atomic.h>
 
 #include "avc.h"
 #include "objsec.h"
 #include "xfrm.h"
 
+/* Labeled XFRM instance counter */
+atomic_t selinux_xfrm_refcount = ATOMIC_INIT(0);
 
 /*
  * Returns true if an LSM/SELinux context
@@ -293,6 +296,9 @@ int selinux_xfrm_policy_alloc(struct xfrm_policy *xp,
 	BUG_ON(!uctx);
 
 	err = selinux_xfrm_sec_ctx_alloc(&xp->security, uctx, 0);
+	if (err == 0)
+		atomic_inc(&selinux_xfrm_refcount);
+
 	return err;
 }
 
@@ -340,10 +346,13 @@ int selinux_xfrm_policy_delete(struct xfrm_policy *xp)
 	struct xfrm_sec_ctx *ctx = xp->security;
 	int rc = 0;
 
-	if (ctx)
+	if (ctx) {
 		rc = avc_has_perm(tsec->sid, ctx->ctx_sid,
 				  SECCLASS_ASSOCIATION,
 				  ASSOCIATION__SETCONTEXT, NULL);
+		if (rc == 0)
+			atomic_dec(&selinux_xfrm_refcount);
+	}
 
 	return rc;
 }
@@ -360,6 +369,8 @@ int selinux_xfrm_state_alloc(struct xfrm_state *x, struct xfrm_user_sec_ctx *uct
 	BUG_ON(!x);
 
 	err = selinux_xfrm_sec_ctx_alloc(&x->security, uctx, secid);
+	if (err == 0)
+		atomic_inc(&selinux_xfrm_refcount);
 	return err;
 }
 
@@ -382,10 +393,13 @@ int selinux_xfrm_state_delete(struct xfrm_state *x)
 	struct xfrm_sec_ctx *ctx = x->security;
 	int rc = 0;
 
-	if (ctx)
+	if (ctx) {
 		rc = avc_has_perm(tsec->sid, ctx->ctx_sid,
 				  SECCLASS_ASSOCIATION,
 				  ASSOCIATION__SETCONTEXT, NULL);
+		if (rc == 0)
+			atomic_dec(&selinux_xfrm_refcount);
+	}
 
 	return rc;
 }