The patch below does not apply to the 4.19-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 9992a078b1771da354ac1f9737e1e639b687caa2 Mon Sep 17 00:00:00 2001
From: Hangbin Liu <liuhangbin@xxxxxxxxx>
Date: Fri, 9 Jul 2021 11:45:02 +0800
Subject: [PATCH] net: ip_tunnel: fix mtu calculation for ETHER tunnel devices
Commit 28e104d00281 ("net: ip_tunnel: fix mtu calculation") removed
dev->hard_header_len subtraction when calculate MTU for tunnel devices
as there is an overhead for device that has header_ops.
But there are ETHER tunnel devices, like gre_tap or erspan, which don't
have header_ops but set dev->hard_header_len during setup. This makes
pkts greater than (MTU - ETH_HLEN) could not be xmited. Fix it by
subtracting the ETHER tunnel devices' dev->hard_header_len for MTU
calculation.
Fixes: 28e104d00281 ("net: ip_tunnel: fix mtu calculation")
Reported-by: Jianlin Shi <jishi@xxxxxxxxxx>
Signed-off-by: Hangbin Liu <liuhangbin@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
index f6cc26de5ed3..0dca00745ac3 100644
--- a/net/ipv4/ip_tunnel.c
+++ b/net/ipv4/ip_tunnel.c
@@ -317,7 +317,7 @@ static int ip_tunnel_bind_dev(struct net_device *dev)
}
dev->needed_headroom = t_hlen + hlen;
- mtu -= t_hlen;
+ mtu -= t_hlen + (dev->type == ARPHRD_ETHER ? dev->hard_header_len : 0);
if (mtu < IPV4_MIN_MTU)
mtu = IPV4_MIN_MTU;
@@ -348,6 +348,9 @@ static struct ip_tunnel *ip_tunnel_create(struct net *net,
t_hlen = nt->hlen + sizeof(struct iphdr);
dev->min_mtu = ETH_MIN_MTU;
dev->max_mtu = IP_MAX_MTU - t_hlen;
+ if (dev->type == ARPHRD_ETHER)
+ dev->max_mtu -= dev->hard_header_len;
+
ip_tunnel_add(itn, nt);
return nt;
@@ -489,11 +492,14 @@ static int tnl_update_pmtu(struct net_device *dev, struct sk_buff *skb,
tunnel_hlen = md ? tunnel_hlen : tunnel->hlen;
pkt_size = skb->len - tunnel_hlen;
+ pkt_size -= dev->type == ARPHRD_ETHER ? dev->hard_header_len : 0;
- if (df)
+ if (df) {
mtu = dst_mtu(&rt->dst) - (sizeof(struct iphdr) + tunnel_hlen);
- else
+ mtu -= dev->type == ARPHRD_ETHER ? dev->hard_header_len : 0;
+ } else {
mtu = skb_valid_dst(skb) ? dst_mtu(skb_dst(skb)) : dev->mtu;
+ }
if (skb_valid_dst(skb))
skb_dst_update_pmtu_no_confirm(skb, mtu);
@@ -972,6 +978,9 @@ int __ip_tunnel_change_mtu(struct net_device *dev, int new_mtu, bool strict)
int t_hlen = tunnel->hlen + sizeof(struct iphdr);
int max_mtu = IP_MAX_MTU - t_hlen;
+ if (dev->type == ARPHRD_ETHER)
+ max_mtu -= dev->hard_header_len;
+
if (new_mtu < ETH_MIN_MTU)
return -EINVAL;
@@ -1149,6 +1158,9 @@ int ip_tunnel_newlink(struct net_device *dev, struct nlattr *tb[],
if (tb[IFLA_MTU]) {
unsigned int max = IP_MAX_MTU - (nt->hlen + sizeof(struct iphdr));
+ if (dev->type == ARPHRD_ETHER)
+ max -= dev->hard_header_len;
+
mtu = clamp(dev->mtu, (unsigned int)ETH_MIN_MTU, max);
}
