[PATCH net-next v2 9/9] ipv4/6: use core net MTU range checking

From: Jarod Wilson
Date: Thu Oct 20 2016 - 13:56:30 EST


ipv4/ip_tunnel:
- min_mtu = 68, max_mtu = 0xFFF8 - dev->hard_header_len - t_hlen
- preserve all ndo_change_mtu checks for now to prevent regressions

ipv6/ip6_tunnel:
- min_mtu = 68, max_mtu = 0xFFF8 - dev->hard_header_len
- preserve all ndo_change_mtu checks for now to prevent regressions

ipv6/ip6_vti:
- min_mtu = 1280, max_mtu = 65535
- remove redundant vti6_change_mtu

ipv6/sit:
- min_mtu = 1280, max_mtu = 0xFFF8 - t_hlen
- remove redundant ipip6_tunnel_change_mtu

CC: netdev@xxxxxxxxxxxxxxx
CC: "David S. Miller" <davem@xxxxxxxxxxxxx>
CC: Alexey Kuznetsov <kuznet@xxxxxxxxxxxxx>
CC: James Morris <jmorris@xxxxxxxxx>
CC: Hideaki YOSHIFUJI <yoshfuji@xxxxxxxxxxxxxx>
CC: Patrick McHardy <kaber@xxxxxxxxx>
Signed-off-by: Jarod Wilson <jarod@xxxxxxxxxx>
---
net/ipv4/ip_tunnel.c | 6 +++++-
net/ipv6/ip6_tunnel.c | 4 +++-
net/ipv6/ip6_vti.c | 21 ++-------------------
net/ipv6/sit.c | 14 ++------------
4 files changed, 12 insertions(+), 33 deletions(-)

diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
index 5719d6b..12a92e3 100644
--- a/net/ipv4/ip_tunnel.c
+++ b/net/ipv4/ip_tunnel.c
@@ -358,6 +358,7 @@ static struct ip_tunnel *ip_tunnel_create(struct net *net,
{
struct ip_tunnel *nt;
struct net_device *dev;
+ int t_hlen;

BUG_ON(!itn->fb_tunnel_dev);
dev = __ip_tunnel_create(net, itn->fb_tunnel_dev->rtnl_link_ops, parms);
@@ -367,6 +368,9 @@ static struct ip_tunnel *ip_tunnel_create(struct net *net,
dev->mtu = ip_tunnel_bind_dev(dev);

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;
ip_tunnel_add(itn, nt);
return nt;
}
@@ -929,7 +933,7 @@ int __ip_tunnel_change_mtu(struct net_device *dev, int new_mtu, bool strict)
int t_hlen = tunnel->hlen + sizeof(struct iphdr);
int max_mtu = 0xFFF8 - dev->hard_header_len - t_hlen;

- if (new_mtu < 68)
+ if (new_mtu < ETH_MIN_MTU)
return -EINVAL;

if (new_mtu > max_mtu) {
diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index 6a66adb..3a70567 100644
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -1634,7 +1634,7 @@ int ip6_tnl_change_mtu(struct net_device *dev, int new_mtu)
struct ip6_tnl *tnl = netdev_priv(dev);

if (tnl->parms.proto == IPPROTO_IPIP) {
- if (new_mtu < 68)
+ if (new_mtu < ETH_MIN_MTU)
return -EINVAL;
} else {
if (new_mtu < IPV6_MIN_MTU)
@@ -1787,6 +1787,8 @@ ip6_tnl_dev_init_gen(struct net_device *dev)
dev->mtu = ETH_DATA_LEN - t_hlen;
if (!(t->parms.flags & IP6_TNL_F_IGN_ENCAP_LIMIT))
dev->mtu -= 8;
+ dev->min_mtu = ETH_MIN_MTU;
+ dev->max_mtu = 0xFFF8 - dev->hard_header_len;

return 0;

diff --git a/net/ipv6/ip6_vti.c b/net/ipv6/ip6_vti.c
index 8a02ca8..35c5b2d 100644
--- a/net/ipv6/ip6_vti.c
+++ b/net/ipv6/ip6_vti.c
@@ -812,30 +812,11 @@ vti6_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
return err;
}

-/**
- * vti6_tnl_change_mtu - change mtu manually for tunnel device
- * @dev: virtual device associated with tunnel
- * @new_mtu: the new mtu
- *
- * Return:
- * 0 on success,
- * %-EINVAL if mtu too small
- **/
-static int vti6_change_mtu(struct net_device *dev, int new_mtu)
-{
- if (new_mtu < IPV6_MIN_MTU)
- return -EINVAL;
-
- dev->mtu = new_mtu;
- return 0;
-}
-
static const struct net_device_ops vti6_netdev_ops = {
.ndo_init = vti6_dev_init,
.ndo_uninit = vti6_dev_uninit,
.ndo_start_xmit = vti6_tnl_xmit,
.ndo_do_ioctl = vti6_ioctl,
- .ndo_change_mtu = vti6_change_mtu,
.ndo_get_stats64 = ip_tunnel_get_stats64,
.ndo_get_iflink = ip6_tnl_get_iflink,
};
@@ -855,6 +836,8 @@ static void vti6_dev_setup(struct net_device *dev)
dev->type = ARPHRD_TUNNEL6;
dev->hard_header_len = LL_MAX_HEADER + sizeof(struct ipv6hdr);
dev->mtu = ETH_DATA_LEN;
+ dev->min_mtu = IPV6_MIN_MTU;
+ dev->max_mtu = IP_MAX_MTU;
dev->flags |= IFF_NOARP;
dev->addr_len = sizeof(struct in6_addr);
netif_keep_dst(dev);
diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
index b1cdf80..dc7a344 100644
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -1318,23 +1318,11 @@ ipip6_tunnel_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
return err;
}

-static int ipip6_tunnel_change_mtu(struct net_device *dev, int new_mtu)
-{
- struct ip_tunnel *tunnel = netdev_priv(dev);
- int t_hlen = tunnel->hlen + sizeof(struct iphdr);
-
- if (new_mtu < IPV6_MIN_MTU || new_mtu > 0xFFF8 - t_hlen)
- return -EINVAL;
- dev->mtu = new_mtu;
- return 0;
-}
-
static const struct net_device_ops ipip6_netdev_ops = {
.ndo_init = ipip6_tunnel_init,
.ndo_uninit = ipip6_tunnel_uninit,
.ndo_start_xmit = sit_tunnel_xmit,
.ndo_do_ioctl = ipip6_tunnel_ioctl,
- .ndo_change_mtu = ipip6_tunnel_change_mtu,
.ndo_get_stats64 = ip_tunnel_get_stats64,
.ndo_get_iflink = ip_tunnel_get_iflink,
};
@@ -1365,6 +1353,8 @@ static void ipip6_tunnel_setup(struct net_device *dev)
dev->type = ARPHRD_SIT;
dev->hard_header_len = LL_MAX_HEADER + t_hlen;
dev->mtu = ETH_DATA_LEN - t_hlen;
+ dev->min_mtu = IPV6_MIN_MTU;
+ dev->max_mtu = 0xFFF8 - t_hlen;
dev->flags = IFF_NOARP;
netif_keep_dst(dev);
dev->addr_len = 4;
--
2.10.0