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ip6_tunnel: update mtu properly for ARPHRD_ETHER tunnel device in tx …
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Now when updating mtu in tx path, it doesn't consider ARPHRD_ETHER tunnel
device, like ip6gre_tap tunnel, for which it should also subtract ether
header to get the correct mtu.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Xin Long authored and David S. Miller committed Oct 1, 2017
1 parent 2d40557 commit d41bb33
Showing 1 changed file with 3 additions and 2 deletions.
5 changes: 3 additions & 2 deletions net/ipv6/ip6_tunnel.c
Original file line number Diff line number Diff line change
Expand Up @@ -1043,6 +1043,7 @@ int ip6_tnl_xmit(struct sk_buff *skb, struct net_device *dev, __u8 dsfield,
struct dst_entry *dst = NULL, *ndst = NULL;
struct net_device *tdev;
int mtu;
unsigned int eth_hlen = t->dev->type == ARPHRD_ETHER ? ETH_HLEN : 0;
unsigned int psh_hlen = sizeof(struct ipv6hdr) + t->encap_hlen;
unsigned int max_headroom = psh_hlen;
bool use_cache = false;
Expand Down Expand Up @@ -1124,7 +1125,7 @@ int ip6_tnl_xmit(struct sk_buff *skb, struct net_device *dev, __u8 dsfield,
t->parms.name);
goto tx_err_dst_release;
}
mtu = dst_mtu(dst) - psh_hlen - t->tun_hlen;
mtu = dst_mtu(dst) - eth_hlen - psh_hlen - t->tun_hlen;
if (encap_limit >= 0) {
max_headroom += 8;
mtu -= 8;
Expand All @@ -1133,7 +1134,7 @@ int ip6_tnl_xmit(struct sk_buff *skb, struct net_device *dev, __u8 dsfield,
mtu = IPV6_MIN_MTU;
if (skb_dst(skb) && !t->parms.collect_md)
skb_dst(skb)->ops->update_pmtu(skb_dst(skb), NULL, skb, mtu);
if (skb->len - t->tun_hlen > mtu && !skb_is_gso(skb)) {
if (skb->len - t->tun_hlen - eth_hlen > mtu && !skb_is_gso(skb)) {
*pmtu = mtu;
err = -EMSGSIZE;
goto tx_err_dst_release;
Expand Down

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