v4.19.13 snapshot.
diff --git a/include/net/gue.h b/include/net/gue.h
new file mode 100644
index 0000000..fdad414
--- /dev/null
+++ b/include/net/gue.h
@@ -0,0 +1,117 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __NET_GUE_H
+#define __NET_GUE_H
+
+/* Definitions for the GUE header, standard and private flags, lengths
+ * of optional fields are below.
+ *
+ * Diagram of GUE header:
+ *
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * |Ver|C| Hlen | Proto/ctype | Standard flags |P|
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * | |
+ * ~ Fields (optional) ~
+ * | |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * | Private flags (optional, P bit is set) |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * | |
+ * ~ Private fields (optional) ~
+ * | |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ *
+ * C bit indicates contol message when set, data message when unset.
+ * For a control message, proto/ctype is interpreted as a type of
+ * control message. For data messages, proto/ctype is the IP protocol
+ * of the next header.
+ *
+ * P bit indicates private flags field is present. The private flags
+ * may refer to options placed after this field.
+ */
+
+struct guehdr {
+ union {
+ struct {
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+ __u8 hlen:5,
+ control:1,
+ version:2;
+#elif defined (__BIG_ENDIAN_BITFIELD)
+ __u8 version:2,
+ control:1,
+ hlen:5;
+#else
+#error "Please fix <asm/byteorder.h>"
+#endif
+ __u8 proto_ctype;
+ __be16 flags;
+ };
+ __be32 word;
+ };
+};
+
+/* Standard flags in GUE header */
+
+#define GUE_FLAG_PRIV htons(1<<0) /* Private flags are in options */
+#define GUE_LEN_PRIV 4
+
+#define GUE_FLAGS_ALL (GUE_FLAG_PRIV)
+
+/* Private flags in the private option extension */
+
+#define GUE_PFLAG_REMCSUM htonl(1 << 31)
+#define GUE_PLEN_REMCSUM 4
+
+#define GUE_PFLAGS_ALL (GUE_PFLAG_REMCSUM)
+
+/* Functions to compute options length corresponding to flags.
+ * If we ever have a lot of flags this can be potentially be
+ * converted to a more optimized algorithm (table lookup
+ * for instance).
+ */
+static inline size_t guehdr_flags_len(__be16 flags)
+{
+ return ((flags & GUE_FLAG_PRIV) ? GUE_LEN_PRIV : 0);
+}
+
+static inline size_t guehdr_priv_flags_len(__be32 flags)
+{
+ return 0;
+}
+
+/* Validate standard and private flags. Returns non-zero (meaning invalid)
+ * if there is an unknown standard or private flags, or the options length for
+ * the flags exceeds the options length specific in hlen of the GUE header.
+ */
+static inline int validate_gue_flags(struct guehdr *guehdr, size_t optlen)
+{
+ __be16 flags = guehdr->flags;
+ size_t len;
+
+ if (flags & ~GUE_FLAGS_ALL)
+ return 1;
+
+ len = guehdr_flags_len(flags);
+ if (len > optlen)
+ return 1;
+
+ if (flags & GUE_FLAG_PRIV) {
+ /* Private flags are last four bytes accounted in
+ * guehdr_flags_len
+ */
+ __be32 pflags = *(__be32 *)((void *)&guehdr[1] +
+ len - GUE_LEN_PRIV);
+
+ if (pflags & ~GUE_PFLAGS_ALL)
+ return 1;
+
+ len += guehdr_priv_flags_len(pflags);
+ if (len > optlen)
+ return 1;
+ }
+
+ return 0;
+}
+
+#endif