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net: ip_tunnel: fix mtu calculation for ETHER tunnel devices

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Commit 28e104d002 ("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: 28e104d002 ("net: ip_tunnel: fix mtu calculation")
Reported-by: Jianlin Shi <jishi@redhat.com>
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Hangbin Liu 2021-07-09 11:45:02 +08:00 • committed by David S. Miller
parent 28b34f01a7
commit 9992a078b1
1 changed files with 15 additions and 3 deletions
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18
net/ipv4/ip_tunnel.c
View file

@ -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);
}