| Message ID | 1484298740-29199-1-git-send-email-jkbs@redhat.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
From: Jakub Sitnicki <jkbs@redhat.com> Date: Fri, 13 Jan 2017 10:12:20 +0100 > With ip6gre we have a tunnel header which also makes the tunnel MTU > smaller. We need to reserve room for it. Previously we were using up > space reserved for the Tunnel Encapsulation Limit option > header (RFC 2473). > > Also, after commit b05229f44228 ("gre6: Cleanup GREv6 transmit path, > call common GRE functions") our contract with the caller has > changed. Now we check if the packet length exceeds the tunnel MTU after > the tunnel header has been pushed, unlike before. > > This is reflected in the check where we look at the packet length minus > the size of the tunnel header, which is already accounted for in tunnel > MTU. > > Fixes: b05229f44228 ("gre6: Cleanup GREv6 transmit path, call common GRE functions") > Signed-off-by: Jakub Sitnicki <jkbs@redhat.com> Applied and queued up for -stable, thanks.
diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c index 36d2921..753d6d0 100644 --- a/net/ipv6/ip6_tunnel.c +++ b/net/ipv6/ip6_tunnel.c @@ -1108,7 +1108,7 @@ 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; + mtu = dst_mtu(dst) - psh_hlen - t->tun_hlen; if (encap_limit >= 0) { max_headroom += 8; mtu -= 8; @@ -1117,7 +1117,7 @@ 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 > mtu && !skb_is_gso(skb)) { + if (skb->len - t->tun_hlen > mtu && !skb_is_gso(skb)) { *pmtu = mtu; err = -EMSGSIZE; goto tx_err_dst_release;
With ip6gre we have a tunnel header which also makes the tunnel MTU smaller. We need to reserve room for it. Previously we were using up space reserved for the Tunnel Encapsulation Limit option header (RFC 2473). Also, after commit b05229f44228 ("gre6: Cleanup GREv6 transmit path, call common GRE functions") our contract with the caller has changed. Now we check if the packet length exceeds the tunnel MTU after the tunnel header has been pushed, unlike before. This is reflected in the check where we look at the packet length minus the size of the tunnel header, which is already accounted for in tunnel MTU. Fixes: b05229f44228 ("gre6: Cleanup GREv6 transmit path, call common GRE functions") Signed-off-by: Jakub Sitnicki <jkbs@redhat.com> --- net/ipv6/ip6_tunnel.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)