NetLabel: Verify sensitivity level has a valid CIPSO mapping

The current CIPSO engine has a problem where it does not verify that the given
sensitivity level has a valid CIPSO mapping when the "std" CIPSO DOI type is
used.  The end result is that bad packets are sent on the wire which should
have never been sent in the first place.  This patch corrects this problem by
verifying the sensitivity level mapping similar to what is done with the
category mapping.  This patch also changes the returned error code in this case
to -EPERM to better match what the category mapping verification code returns.
Signed-off-by: Paul Moore <paul.moore@hp.com>
Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

net/ipv4/cipso_ipv4.c

@@ -732,11 +732,12 @@ static int cipso_v4_map_lvl_hton(const struct cipso_v4_doi *doi_def,
 		*net_lvl = host_lvl;
 		return 0;
 	case CIPSO_V4_MAP_STD:
-		if (host_lvl < doi_def->map.std->lvl.local_size) {
+		if (host_lvl < doi_def->map.std->lvl.local_size &&
+		    doi_def->map.std->lvl.local[host_lvl] < CIPSO_V4_INV_LVL) {
 			*net_lvl = doi_def->map.std->lvl.local[host_lvl];
 			return 0;
 		}
-		break;
+		return -EPERM;
 	}
 
 	return -EINVAL;
@@ -771,7 +772,7 @@ static int cipso_v4_map_lvl_ntoh(const struct cipso_v4_doi *doi_def,
 			*host_lvl = doi_def->map.std->lvl.cipso[net_lvl];
 			return 0;
 		}
-		break;
+		return -EPERM;
 	}
 
 	return -EINVAL;