selinux/nlmsg: add XFRM_MSG_MAPPING

This command is missing.

Fixes: 3a2dfbe8 ("xfrm: Notify changes in UDP encapsulation via netlink")
CC: Martin Willi <martin@strongswan.org>
Reported-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

security/selinux/nlmsgtab.c

@@ -109,6 +109,7 @@ static struct nlmsg_perm nlmsg_xfrm_perms[] =
 	{ XFRM_MSG_GETSADINFO,	NETLINK_XFRM_SOCKET__NLMSG_READ  },
 	{ XFRM_MSG_NEWSPDINFO,	NETLINK_XFRM_SOCKET__NLMSG_WRITE },
 	{ XFRM_MSG_GETSPDINFO,	NETLINK_XFRM_SOCKET__NLMSG_READ  },
+	{ XFRM_MSG_MAPPING,	NETLINK_XFRM_SOCKET__NLMSG_READ  },
 };
 
 static struct nlmsg_perm nlmsg_audit_perms[] =