Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/net/ipv4/gre_demux.c b/net/ipv4/gre_demux.c
index b798862..44bfeec 100644
--- a/net/ipv4/gre_demux.c
+++ b/net/ipv4/gre_demux.c
@@ -1,13 +1,8 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /*
  *	GRE over IPv4 demultiplexer driver
  *
  *	Authors: Dmitry Kozlov (xeb@mail.ru)
- *
- *	This program is free software; you can redistribute it and/or
- *	modify it under the terms of the GNU General Public License
- *	as published by the Free Software Foundation; either version
- *	2 of the License, or (at your option) any later version.
- *
  */
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
@@ -25,6 +20,7 @@
 #include <linux/spinlock.h>
 #include <net/protocol.h>
 #include <net/gre.h>
+#include <net/erspan.h>
 
 #include <net/icmp.h>
 #include <net/route.h>
@@ -86,13 +82,14 @@
 
 	options = (__be32 *)(greh + 1);
 	if (greh->flags & GRE_CSUM) {
-		if (skb_checksum_simple_validate(skb)) {
+		if (!skb_checksum_simple_validate(skb)) {
+			skb_checksum_try_convert(skb, IPPROTO_GRE,
+						 null_compute_pseudo);
+		} else if (csum_err) {
 			*csum_err = true;
 			return -EINVAL;
 		}
 
-		skb_checksum_try_convert(skb, IPPROTO_GRE, 0,
-					 null_compute_pseudo);
 		options++;
 	}
 
@@ -118,6 +115,22 @@
 			hdr_len += 4;
 	}
 	tpi->hdr_len = hdr_len;
+
+	/* ERSPAN ver 1 and 2 protocol sets GRE key field
+	 * to 0 and sets the configured key in the
+	 * inner erspan header field
+	 */
+	if (greh->protocol == htons(ETH_P_ERSPAN) ||
+	    greh->protocol == htons(ETH_P_ERSPAN2)) {
+		struct erspan_base_hdr *ershdr;
+
+		if (!pskb_may_pull(skb, nhs + hdr_len + sizeof(*ershdr)))
+			return -EINVAL;
+
+		ershdr = (struct erspan_base_hdr *)options;
+		tpi->key = cpu_to_be32(get_session_id(ershdr));
+	}
+
 	return hdr_len;
 }
 EXPORT_SYMBOL(gre_parse_header);
@@ -150,20 +163,25 @@
 	return NET_RX_DROP;
 }
 
-static void gre_err(struct sk_buff *skb, u32 info)
+static int gre_err(struct sk_buff *skb, u32 info)
 {
 	const struct gre_protocol *proto;
 	const struct iphdr *iph = (const struct iphdr *)skb->data;
 	u8 ver = skb->data[(iph->ihl<<2) + 1]&0x7f;
+	int err = 0;
 
 	if (ver >= GREPROTO_MAX)
-		return;
+		return -EINVAL;
 
 	rcu_read_lock();
 	proto = rcu_dereference(gre_proto[ver]);
 	if (proto && proto->err_handler)
 		proto->err_handler(skb, info);
+	else
+		err = -EPROTONOSUPPORT;
 	rcu_read_unlock();
+
+	return err;
 }
 
 static const struct net_protocol net_gre_protocol = {