mpls: Prevent use of implicit NULL label as outgoing label
The reserved implicit-NULL label isn't allowed to appear in the label
stack for packets, so make it an error for the control plane to
specify it as an outgoing label.
Suggested-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Robert Shearman <rshearma@brocade.com>
Reviewed-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c
index 9fdd94c..954810c 100644
--- a/net/mpls/af_mpls.c
+++ b/net/mpls/af_mpls.c
@@ -646,6 +646,15 @@
if ((dec.bos != bos) || dec.ttl || dec.tc)
return -EINVAL;
+ switch (dec.label) {
+ case LABEL_IMPLICIT_NULL:
+ /* RFC3032: This is a label that an LSR may
+ * assign and distribute, but which never
+ * actually appears in the encapsulation.
+ */
+ return -EINVAL;
+ }
+
label[i] = dec.label;
}
*labels = nla_labels;