[PATCH 5.4 24/37] Fixed updating of ethertype in function skb_mpls_pop

[Greg Kroah-Hartman]

From: Martin Varghese <martin.varghese@xxxxxxxxx>

[ Upstream commit 040b5cfbcefa263ccf2c118c4938308606bb7ed8 ]

The skb_mpls_pop was not updating ethertype of an ethernet packet if the
packet was originally received from a non ARPHRD_ETHER device.

In the below OVS data path flow, since the device corresponding to port 7
is an l3 device (ARPHRD_NONE) the skb_mpls_pop function does not update
the ethertype of the packet even though the previous push_eth action had
added an ethernet header to the packet.

recirc_id(0),in_port(7),eth_type(0x8847),
mpls(label=12/0xfffff,tc=0/0,ttl=0/0x0,bos=1/1),
actions:push_eth(src=00:00:00:00:00:00,dst=00:00:00:00:00:00),
pop_mpls(eth_type=0x800),4

Fixes: ed246cee09b9 ("net: core: move pop MPLS functionality from OvS to core helper")
Signed-off-by: Martin Varghese <martin.varghese@xxxxxxxxx>
Acked-by: Pravin B Shelar <pshelar@xxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 include/linux/skbuff.h    |    3 ++-
 net/core/skbuff.c         |    6 ++++--
 net/openvswitch/actions.c |    3 ++-
 net/sched/act_mpls.c      |    4 +++-
 4 files changed, 11 insertions(+), 5 deletions(-)

--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -3528,7 +3528,8 @@ int skb_vlan_pop(struct sk_buff *skb);
 int skb_vlan_push(struct sk_buff *skb, __be16 vlan_proto, u16 vlan_tci);
 int skb_mpls_push(struct sk_buff *skb, __be32 mpls_lse, __be16 mpls_proto,
 		  int mac_len);
-int skb_mpls_pop(struct sk_buff *skb, __be16 next_proto, int mac_len);
+int skb_mpls_pop(struct sk_buff *skb, __be16 next_proto, int mac_len,
+		 bool ethernet);
 int skb_mpls_update_lse(struct sk_buff *skb, __be32 mpls_lse);
 int skb_mpls_dec_ttl(struct sk_buff *skb);
 struct sk_buff *pskb_extract(struct sk_buff *skb, int off, int to_copy,
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -5529,12 +5529,14 @@ EXPORT_SYMBOL_GPL(skb_mpls_push);
  * @skb: buffer
  * @next_proto: ethertype of header after popped MPLS header
  * @mac_len: length of the MAC header
+ * @ethernet: flag to indicate if ethernet header is present in packet
  *
  * Expects skb->data at mac header.
  *
  * Returns 0 on success, -errno otherwise.
  */
-int skb_mpls_pop(struct sk_buff *skb, __be16 next_proto, int mac_len)
+int skb_mpls_pop(struct sk_buff *skb, __be16 next_proto, int mac_len,
+		 bool ethernet)
 {
 	int err;
 
@@ -5553,7 +5555,7 @@ int skb_mpls_pop(struct sk_buff *skb, __
 	skb_reset_mac_header(skb);
 	skb_set_network_header(skb, mac_len);
 
-	if (skb->dev && skb->dev->type == ARPHRD_ETHER) {
+	if (ethernet) {
 		struct ethhdr *hdr;
 
 		/* use mpls_hdr() to get ethertype to account for VLANs. */
--- a/net/openvswitch/actions.c
+++ b/net/openvswitch/actions.c
@@ -179,7 +179,8 @@ static int pop_mpls(struct sk_buff *skb,
 {
 	int err;
 
-	err = skb_mpls_pop(skb, ethertype, skb->mac_len);
+	err = skb_mpls_pop(skb, ethertype, skb->mac_len,
+			   ovs_key_mac_proto(key) == MAC_PROTO_ETHERNET);
 	if (err)
 		return err;
 
--- a/net/sched/act_mpls.c
+++ b/net/sched/act_mpls.c
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
 /* Copyright (C) 2019 Netronome Systems, Inc. */
 
+#include <linux/if_arp.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
@@ -76,7 +77,8 @@ static int tcf_mpls_act(struct sk_buff *
 
 	switch (p->tcfm_action) {
 	case TCA_MPLS_ACT_POP:
-		if (skb_mpls_pop(skb, p->tcfm_proto, mac_len))
+		if (skb_mpls_pop(skb, p->tcfm_proto, mac_len,
+				 skb->dev && skb->dev->type == ARPHRD_ETHER))
 			goto drop;
 		break;
 	case TCA_MPLS_ACT_PUSH: