selinux: wrap global selinux state

Define a selinux state structure (struct selinux_state) for
global SELinux state and pass it explicitly to all security server
functions.  The public portion of the structure contains state
that is used throughout the SELinux code, such as the enforcing mode.
The structure also contains a pointer to a selinux_ss structure whose
definition is private to the security server and contains security
server specific state such as the policy database and SID table.

This change should have no effect on SELinux behavior or APIs
(userspace or LSM).  It merely wraps SELinux state and passes it
explicitly as needed.

Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
[PM: minor fixups needed due to collisions with the SCTP patches]
Signed-off-by: Paul Moore <paul@paul-moore.com>

Author: stephensmalley

security/selinux/avc.c

@@ -149,15 +149,17 @@ static void avc_dump_query(struct audit_buffer *ab, u32 ssid, u32 tsid, u16 tcla
 	char *scontext;
 	u32 scontext_len;
 
-	rc = security_sid_to_context(ssid, &scontext, &scontext_len);
+	rc = security_sid_to_context(&selinux_state, ssid,
+				     &scontext, &scontext_len);
 	if (rc)
 		audit_log_format(ab, "ssid=%d", ssid);
 	else {
 		audit_log_format(ab, "scontext=%s", scontext);
 		kfree(scontext);
 	}
 
-	rc = security_sid_to_context(tsid, &scontext, &scontext_len);
+	rc = security_sid_to_context(&selinux_state, tsid,
+				     &scontext, &scontext_len);
 	if (rc)
 		audit_log_format(ab, " tsid=%d", tsid);
 	else {
@@ -969,7 +971,8 @@ static noinline struct avc_node *avc_compute_av(u32 ssid, u32 tsid,
 {
 	rcu_read_unlock();
 	INIT_LIST_HEAD(&xp_node->xpd_head);
-	security_compute_av(ssid, tsid, tclass, avd, &xp_node->xp);
+	security_compute_av(&selinux_state, ssid, tsid, tclass,
+			    avd, &xp_node->xp);
 	rcu_read_lock();
 	return avc_insert(ssid, tsid, tclass, avd, xp_node);
 }
@@ -982,7 +985,8 @@ static noinline int avc_denied(u32 ssid, u32 tsid,
 	if (flags & AVC_STRICT)
 		return -EACCES;
 
-	if (selinux_enforcing && !(avd->flags & AVD_FLAGS_PERMISSIVE))
+	if (is_enforcing(&selinux_state) &&
+	    !(avd->flags & AVD_FLAGS_PERMISSIVE))
 		return -EACCES;
 
 	avc_update_node(AVC_CALLBACK_GRANT, requested, driver, xperm, ssid,
@@ -1043,8 +1047,8 @@ int avc_has_extended_perms(u32 ssid, u32 tsid, u16 tclass, u32 requested,
 			goto decision;
 		}
 		rcu_read_unlock();
-		security_compute_xperms_decision(ssid, tsid, tclass, driver,
-						&local_xpd);
+		security_compute_xperms_decision(&selinux_state, ssid, tsid,
+						 tclass, driver, &local_xpd);
 		rcu_read_lock();
 		avc_update_node(AVC_CALLBACK_ADD_XPERMS, requested, driver, xperm,
 				ssid, tsid, tclass, avd.seqno, &local_xpd, 0);