6 files changed, 87 insertions, 22 deletions

diff --git a/drivers/net/geneve.c b/drivers/net/geneve.c
index 0b14ac3b8d11..028e3873c310 100644
--- a/drivers/net/geneve.c
+++ b/drivers/net/geneve.c
@@ -1039,6 +1039,17 @@ static netdev_tx_t geneve_xmit(struct sk_buff *skb, struct net_device *dev)
         return geneve_xmit_skb(skb, dev, info);
 }
 
+static int geneve_change_mtu(struct net_device *dev, int new_mtu)
+{
+        /* GENEVE overhead is not fixed, so we can't enforce a more
+         * precise max MTU.
+         */
+        if (new_mtu < 68 || new_mtu > IP_MAX_MTU)
+                return -EINVAL;
+        dev->mtu = new_mtu;
+        return 0;
+}
+
 static int geneve_fill_metadata_dst(struct net_device *dev, struct sk_buff *skb)
 {
         struct ip_tunnel_info *info = skb_tunnel_info(skb);
@@ -1083,7 +1094,7 @@ static const struct net_device_ops geneve_netdev_ops = {
         .ndo_stop               = geneve_stop,
         .ndo_start_xmit         = geneve_xmit,
         .ndo_get_stats64        = ip_tunnel_get_stats64,
-        .ndo_change_mtu         = eth_change_mtu,
+        .ndo_change_mtu         = geneve_change_mtu,
         .ndo_validate_addr      = eth_validate_addr,
         .ndo_set_mac_address    = eth_mac_addr,
         .ndo_fill_metadata_dst  = geneve_fill_metadata_dst,
@@ -1442,11 +1453,21 @@ struct net_device *geneve_dev_create_fb(struct net *net, const char *name,
 
         err = geneve_configure(net, dev, &geneve_remote_unspec,
                                0, 0, 0, htons(dst_port), true, 0);
-        if (err) {
-                free_netdev(dev);
-                return ERR_PTR(err);
-        }
+        if (err)
+                goto err;
+
+        /* openvswitch users expect packet sizes to be unrestricted,
+         * so set the largest MTU we can.
+         */
+        err = geneve_change_mtu(dev, IP_MAX_MTU);
+        if (err)
+                goto err;
+
         return dev;
+
+ err:
+        free_netdev(dev);
+        return ERR_PTR(err);
 }
 EXPORT_SYMBOL_GPL(geneve_dev_create_fb);
 
diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index 65439188c582..a31cd954b308 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -2367,29 +2367,43 @@ static void vxlan_set_multicast_list(struct net_device *dev)
 {
 }
 
-static int vxlan_change_mtu(struct net_device *dev, int new_mtu)
+static int __vxlan_change_mtu(struct net_device *dev,
+                              struct net_device *lowerdev,
+                              struct vxlan_rdst *dst, int new_mtu, bool strict)
 {
-        struct vxlan_dev *vxlan = netdev_priv(dev);
-        struct vxlan_rdst *dst = &vxlan->default_dst;
-        struct net_device *lowerdev;
-        int max_mtu;
+        int max_mtu = IP_MAX_MTU;
 
-        lowerdev = __dev_get_by_index(vxlan->net, dst->remote_ifindex);
-        if (lowerdev == NULL)
-                return eth_change_mtu(dev, new_mtu);
+        if (lowerdev)
+                max_mtu = lowerdev->mtu;
 
         if (dst->remote_ip.sa.sa_family == AF_INET6)
-                max_mtu = lowerdev->mtu - VXLAN6_HEADROOM;
+                max_mtu -= VXLAN6_HEADROOM;
         else
-                max_mtu = lowerdev->mtu - VXLAN_HEADROOM;
+                max_mtu -= VXLAN_HEADROOM;
 
-        if (new_mtu < 68 || new_mtu > max_mtu)
+        if (new_mtu < 68)
                 return -EINVAL;
 
+        if (new_mtu > max_mtu) {
+                if (strict)
+                        return -EINVAL;
+
+                new_mtu = max_mtu;
+        }
+
         dev->mtu = new_mtu;
         return 0;
 }
 
+static int vxlan_change_mtu(struct net_device *dev, int new_mtu)
+{
+        struct vxlan_dev *vxlan = netdev_priv(dev);
+        struct vxlan_rdst *dst = &vxlan->default_dst;
+        struct net_device *lowerdev = __dev_get_by_index(vxlan->net,
+                                                         dst->remote_ifindex);
+        return __vxlan_change_mtu(dev, lowerdev, dst, new_mtu, true);
+}
+
 static int egress_ipv4_tun_info(struct net_device *dev, struct sk_buff *skb,
                                 struct ip_tunnel_info *info,
                                 __be16 sport, __be16 dport)
@@ -2765,6 +2779,7 @@ static int vxlan_dev_configure(struct net *src_net, struct net_device *dev,
         int err;
         bool use_ipv6 = false;
         __be16 default_port = vxlan->cfg.dst_port;
+        struct net_device *lowerdev = NULL;
 
         vxlan->net = src_net;
 
@@ -2785,9 +2800,7 @@ static int vxlan_dev_configure(struct net *src_net, struct net_device *dev,
         }
 
         if (conf->remote_ifindex) {
-                struct net_device *lowerdev
-                         = __dev_get_by_index(src_net, conf->remote_ifindex);
-
+                lowerdev = __dev_get_by_index(src_net, conf->remote_ifindex);
                 dst->remote_ifindex = conf->remote_ifindex;
 
                 if (!lowerdev) {
@@ -2811,6 +2824,12 @@ static int vxlan_dev_configure(struct net *src_net, struct net_device *dev,
                 needed_headroom = lowerdev->hard_header_len;
         }
 
+        if (conf->mtu) {
+                err = __vxlan_change_mtu(dev, lowerdev, dst, conf->mtu, false);
+                if (err)
+                        return err;
+        }
+
         if (use_ipv6 || conf->flags & VXLAN_F_COLLECT_METADATA)
                 needed_headroom += VXLAN6_HEADROOM;
         else
diff --git a/include/net/ip_tunnels.h b/include/net/ip_tunnels.h
index 6db96ea0144f..dda9abf6b89c 100644
--- a/include/net/ip_tunnels.h
+++ b/include/net/ip_tunnels.h
@@ -230,6 +230,7 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
 int ip_tunnel_ioctl(struct net_device *dev, struct ip_tunnel_parm *p, int cmd);
 int ip_tunnel_encap(struct sk_buff *skb, struct ip_tunnel *t,
                     u8 *protocol, struct flowi4 *fl4);
+int __ip_tunnel_change_mtu(struct net_device *dev, int new_mtu, bool strict);
 int ip_tunnel_change_mtu(struct net_device *dev, int new_mtu);
 
 struct rtnl_link_stats64 *ip_tunnel_get_stats64(struct net_device *dev,
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 7c51c4e1661f..56fdf4e0dce4 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -1240,6 +1240,14 @@ struct net_device *gretap_fb_dev_create(struct net *net, const char *name,
         err = ipgre_newlink(net, dev, tb, NULL);
         if (err < 0)
                 goto out;
+
+        /* openvswitch users expect packet sizes to be unrestricted,
+         * so set the largest MTU we can.
+         */
+        err = __ip_tunnel_change_mtu(dev, IP_MAX_MTU, false);
+        if (err)
+                goto out;
+
         return dev;
 out:
         free_netdev(dev);
diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
index c7bd72e9b544..89e8861e05fc 100644
--- a/net/ipv4/ip_tunnel.c
+++ b/net/ipv4/ip_tunnel.c
@@ -943,17 +943,31 @@ done:
 }
 EXPORT_SYMBOL_GPL(ip_tunnel_ioctl);
 
-int ip_tunnel_change_mtu(struct net_device *dev, int new_mtu)
+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;
 
-        if (new_mtu < 68 ||
-            new_mtu > 0xFFF8 - dev->hard_header_len - t_hlen)
+        if (new_mtu < 68)
                 return -EINVAL;
+
+        if (new_mtu > max_mtu) {
+                if (strict)
+                        return -EINVAL;
+
+                new_mtu = max_mtu;
+        }
+
         dev->mtu = new_mtu;
         return 0;
 }
+EXPORT_SYMBOL_GPL(__ip_tunnel_change_mtu);
+
+int ip_tunnel_change_mtu(struct net_device *dev, int new_mtu)
+{
+        return __ip_tunnel_change_mtu(dev, new_mtu, true);
+}
 EXPORT_SYMBOL_GPL(ip_tunnel_change_mtu);
 
 static void ip_tunnel_dev_free(struct net_device *dev)
diff --git a/net/openvswitch/vport-vxlan.c b/net/openvswitch/vport-vxlan.c
index 1605691d9414..de9cb19efb6a 100644
--- a/net/openvswitch/vport-vxlan.c
+++ b/net/openvswitch/vport-vxlan.c
@@ -91,6 +91,8 @@ static struct vport *vxlan_tnl_create(const struct vport_parms *parms)
         struct vxlan_config conf = {
                 .no_share = true,
                 .flags = VXLAN_F_COLLECT_METADATA,
+                /* Don't restrict the packets that can be sent by MTU */
+                .mtu = IP_MAX_MTU,
         };
 
         if (!options) {