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authorVadim Fedorenko <vfedorenko@novek.ru>2021-01-30 01:27:47 +0300
committerJakub Kicinski <kuba@kernel.org>2021-02-01 19:58:23 -0800
commit28e104d00281ade30250b24e098bf50887671ea4 (patch)
tree6cae5c0b2a5f65e65718ecddc5f173d19c890195 /net/ipv4
parentc518adafa39f37858697ac9309c6cf1805581446 (diff)
net: ip_tunnel: fix mtu calculation
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: fdafed459998 ("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>
Diffstat (limited to 'net/ipv4')
-rw-r--r--net/ipv4/ip_tunnel.c16
1 files changed, 7 insertions, 9 deletions
diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
index 64594aa755f0..76a420c76f16 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 -= (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);