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, 12 insertions, 0 deletions

diff --git a/security/selinux/include/xfrm.h b/security/selinux/include/xfrm.h
index 31929e39f5ca..36b0510efa7b 100644
--- a/security/selinux/include/xfrm.h
+++ b/security/selinux/include/xfrm.h
@@ -32,6 +32,13 @@ static inline struct inode_security_struct *get_sock_isec(struct sock *sk)
 }
 
 #ifdef CONFIG_SECURITY_NETWORK_XFRM
+extern atomic_t selinux_xfrm_refcount;
+
+static inline int selinux_xfrm_enabled(void)
+{
+        return (atomic_read(&selinux_xfrm_refcount) > 0);
+}
+
 int selinux_xfrm_sock_rcv_skb(u32 sid, struct sk_buff *skb,
                         struct avc_audit_data *ad);
 int selinux_xfrm_postroute_last(u32 isec_sid, struct sk_buff *skb,
@@ -43,6 +50,11 @@ static inline void selinux_xfrm_notify_policyload(void)
         atomic_inc(&flow_cache_genid);
 }
 #else
+static inline int selinux_xfrm_enabled(void)
+{
+        return 0;
+}
+
 static inline int selinux_xfrm_sock_rcv_skb(u32 isec_sid, struct sk_buff *skb,
                         struct avc_audit_data *ad)
 {