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| author | Nicolas Dichtel <nicolas.dichtel@6wind.com> | 2018-05-31 10:59:32 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2018-06-01 13:56:29 -0400 |
| commit | 82612de1c98e610d194e34178bde3cca7dedce41 (patch) | |
| tree | 383941b19ac9d250901bf771c2bd44d59ca70208 /net/ipv4/ip_tunnel.c | |
| parent | ccfde6e27d9566bee596d41a2cc6f158af8595d5 (diff) | |
ip_tunnel: restore binding to ifaces with a large mtu
After commit f6cc9c054e77, the following conf is broken (note that the
default loopback mtu is 65536, ie IP_MAX_MTU + 1):
$ ip tunnel add gre1 mode gre local 10.125.0.1 remote 10.125.0.2 dev lo
add tunnel "gre0" failed: Invalid argument
$ ip l a type dummy
$ ip l s dummy1 up
$ ip l s dummy1 mtu 65535
$ ip tunnel add gre1 mode gre local 10.125.0.1 remote 10.125.0.2 dev dummy1
add tunnel "gre0" failed: Invalid argument
dev_set_mtu() doesn't allow to set a mtu which is too large.
First, let's cap the mtu returned by ip_tunnel_bind_dev(). Second, remove
the magic value 0xFFF8 and use IP_MAX_MTU instead.
0xFFF8 seems to be there for ages, I don't know why this value was used.
With a recent kernel, it's also possible to set a mtu > IP_MAX_MTU:
$ ip l s dummy1 mtu 66000
After that patch, it's also possible to bind an ip tunnel on that kind of
interface.
CC: Petr Machata <petrm@mellanox.com>
CC: Ido Schimmel <idosch@mellanox.com>
Link: https://git.kernel.org/pub/scm/linux/kernel/git/davem/netdev-vger-cvs.git/commit/?id=e5afd356a411a
Fixes: f6cc9c054e77 ("ip_tunnel: Emit events for post-register MTU changes")
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/ip_tunnel.c')
| -rw-r--r-- | net/ipv4/ip_tunnel.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c index 6b0e362cc99b..38d906baf1df 100644 --- a/net/ipv4/ip_tunnel.c +++ b/net/ipv4/ip_tunnel.c @@ -328,7 +328,7 @@ static int ip_tunnel_bind_dev(struct net_device *dev) if (tdev) { hlen = tdev->hard_header_len + tdev->needed_headroom; - mtu = tdev->mtu; + mtu = min(tdev->mtu, IP_MAX_MTU); } dev->needed_headroom = t_hlen + hlen; @@ -362,7 +362,7 @@ 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 = 0xFFF8 - dev->hard_header_len - t_hlen; + dev->max_mtu = IP_MAX_MTU - dev->hard_header_len - t_hlen; ip_tunnel_add(itn, nt); return nt; @@ -930,7 +930,7 @@ 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 = 0xFFF8 - dev->hard_header_len - t_hlen; + int max_mtu = IP_MAX_MTU - dev->hard_header_len - t_hlen; if (new_mtu < ETH_MIN_MTU) return -EINVAL; @@ -1107,7 +1107,7 @@ int ip_tunnel_newlink(struct net_device *dev, struct nlattr *tb[], mtu = ip_tunnel_bind_dev(dev); if (tb[IFLA_MTU]) { - unsigned int max = 0xfff8 - dev->hard_header_len - nt->hlen; + unsigned int max = IP_MAX_MTU - dev->hard_header_len - nt->hlen; mtu = clamp(dev->mtu, (unsigned int)ETH_MIN_MTU, (unsigned int)(max - sizeof(struct iphdr))); |