[IPv6]: Verify ND options properly.

include/net/ndisc.h

@@ -51,6 +51,25 @@ struct ra_msg {
 	__u32			retrans_timer;
 };
 
+struct nd_opt_hdr {
+	__u8		nd_opt_type;
+	__u8		nd_opt_len;
+} __attribute__((__packed__));
+
+struct ndisc_options {
+	struct nd_opt_hdr *nd_opt_array[7];
+	struct nd_opt_hdr *nd_opt_piend;
+};
+
+#define nd_opts_src_lladdr	nd_opt_array[ND_OPT_SOURCE_LL_ADDR]
+#define nd_opts_tgt_lladdr	nd_opt_array[ND_OPT_TARGET_LL_ADDR]
+#define nd_opts_pi		nd_opt_array[ND_OPT_PREFIX_INFO]
+#define nd_opts_pi_end		nd_opt_piend
+#define nd_opts_rh		nd_opt_array[ND_OPT_REDIRECT_HDR]
+#define nd_opts_mtu		nd_opt_array[ND_OPT_MTU]
+
+extern struct nd_opt_hdr *ndisc_next_option(struct nd_opt_hdr *cur, struct nd_opt_hdr *end);
+extern struct ndisc_options *ndisc_parse_options(u8 *opt, int opt_len, struct ndisc_options *ndopts);
 
 extern int			ndisc_init(struct net_proto_family *ops);