neighbor: NTF_PROXY is a valid ndm_flag for a dump request

When dumping proxy entries the dump request has NTF_PROXY set in
ndm_flags. strict mode checking needs to be updated to allow this
flag.

Fixes: 51183d23 ("net/neighbor: Update neigh_dump_info for strict data checking")
Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/neighbour.c

@@ -2494,11 +2494,16 @@ static int neigh_valid_dump_req(const struct nlmsghdr *nlh,
 
 		ndm = nlmsg_data(nlh);
 		if (ndm->ndm_pad1  || ndm->ndm_pad2  || ndm->ndm_ifindex ||
-		    ndm->ndm_state || ndm->ndm_flags || ndm->ndm_type) {
+		    ndm->ndm_state || ndm->ndm_type) {
 			NL_SET_ERR_MSG(extack, "Invalid values in header for neighbor dump request");
 			return -EINVAL;
 		}
 
+		if (ndm->ndm_flags & ~NTF_PROXY) {
+			NL_SET_ERR_MSG(extack, "Invalid flags in header for neighbor dump request");
+			return -EINVAL;
+		}
+
 		err = nlmsg_parse_strict(nlh, sizeof(struct ndmsg), tb, NDA_MAX,
 					 NULL, extack);
 	} else {