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net: ip_tunnel: fix mtu calculation

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dev->hard_header_len for tunnel interface is set only when header_ops
are set too and already contains full overhead of any tunnel encapsulation.
That's why there is not need to use this overhead twice in mtu calc.

Fixes: fdafed4599 ("ip_gre: set dev->hard_header_len and dev->needed_headroom properly")
Reported-by: Slava Bacherikov <mail@slava.cc>
Signed-off-by: Vadim Fedorenko <vfedorenko@novek.ru>
Link: https://lore.kernel.org/r/1611959267-20536-1-git-send-email-vfedorenko@novek.ru
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Vadim Fedorenko 2021-01-30 01:27:47 +03:00 committed by Jakub Kicinski
parent c518adafa3
commit 28e104d002
1 changed files with 7 additions and 9 deletions
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16
net/ipv4/ip_tunnel.c
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@ -317,7 +317,7 @@ static int ip_tunnel_bind_dev(struct net_device *dev)
}
dev->needed_headroom = t_hlen + hlen;
mtu -= (dev->hard_header_len + t_hlen);
mtu -= t_hlen;
if (mtu < IPV4_MIN_MTU)
mtu = IPV4_MIN_MTU;
@ -347,7 +347,7 @@ static struct ip_tunnel *ip_tunnel_create(struct net *net,
nt = netdev_priv(dev);
t_hlen = nt->hlen + sizeof(struct iphdr);
dev->min_mtu = ETH_MIN_MTU;
dev->max_mtu = IP_MAX_MTU - dev->hard_header_len - t_hlen;
dev->max_mtu = IP_MAX_MTU - t_hlen;
ip_tunnel_add(itn, nt);
return nt;
@ -488,11 +488,10 @@ static int tnl_update_pmtu(struct net_device *dev, struct sk_buff *skb,
int mtu;
tunnel_hlen = md ? tunnel_hlen : tunnel->hlen;
pkt_size = skb->len - tunnel_hlen - dev->hard_header_len;
pkt_size = skb->len - tunnel_hlen;
if (df)
mtu = dst_mtu(&rt->dst) - dev->hard_header_len
- sizeof(struct iphdr) - tunnel_hlen;
mtu = dst_mtu(&rt->dst) - (sizeof(struct iphdr) + tunnel_hlen);
else
mtu = skb_valid_dst(skb) ? dst_mtu(skb_dst(skb)) : dev->mtu;
@ -972,7 +971,7 @@ int __ip_tunnel_change_mtu(struct net_device *dev, int new_mtu, bool strict)
{
struct ip_tunnel *tunnel = netdev_priv(dev);
int t_hlen = tunnel->hlen + sizeof(struct iphdr);
int max_mtu = IP_MAX_MTU - dev->hard_header_len - t_hlen;
int max_mtu = IP_MAX_MTU - t_hlen;
if (new_mtu < ETH_MIN_MTU)
return -EINVAL;
@ -1149,10 +1148,9 @@ int ip_tunnel_newlink(struct net_device *dev, struct nlattr *tb[],
mtu = ip_tunnel_bind_dev(dev);
if (tb[IFLA_MTU]) {
unsigned int max = IP_MAX_MTU - dev->hard_header_len - nt->hlen;
unsigned int max = IP_MAX_MTU - (nt->hlen + sizeof(struct iphdr));
mtu = clamp(dev->mtu, (unsigned int)ETH_MIN_MTU,
(unsigned int)(max - sizeof(struct iphdr)));
mtu = clamp(dev->mtu, (unsigned int)ETH_MIN_MTU, max);
}
err = dev_set_mtu(dev, mtu);