[PATCH net-next] openvswitch: correctly fragment packet with mpls headers

[Jiri Benc]

If mpls headers were pushed to a defragmented packet, the refragmentation no
longer works correctly after 48d2ab609b6b ("net: mpls: Fixups for GSO"). The
network header has to be shifted after the mpls headers for the
fragmentation and restored afterwards.

Fixes: 48d2ab609b6b ("net: mpls: Fixups for GSO")
Signed-off-by: Jiri Benc <jb...@redhat.com>
---
 net/openvswitch/actions.c | 26 +++++++++++++++++++++-----
 1 file changed, 21 insertions(+), 5 deletions(-)

diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
index 4e03f64709bc..370b2ba3df4c 100644
--- a/net/openvswitch/actions.c
+++ b/net/openvswitch/actions.c
@@ -62,7 +62,8 @@ struct ovs_frag_data {
        struct vport *vport;
        struct ovs_skb_cb cb;
        __be16 inner_protocol;
-       __u16 vlan_tci;
+       u16 network_offset;     /* valid only if inner_protocol is set */
+       u16 vlan_tci;
        __be16 vlan_proto;
        unsigned int l2_len;
        u8 l2_data[MAX_L2_LEN];
@@ -656,7 +657,6 @@ static int ovs_vport_output(struct net *net, struct sock 
*sk, struct sk_buff *sk
 
        __skb_dst_copy(skb, data->dst);
        *OVS_CB(skb) = data->cb;
-       skb->inner_protocol = data->inner_protocol;
        skb->vlan_tci = data->vlan_tci;
        skb->vlan_proto = data->vlan_proto;
 
@@ -666,6 +666,13 @@ static int ovs_vport_output(struct net *net, struct sock 
*sk, struct sk_buff *sk
        skb_postpush_rcsum(skb, skb->data, data->l2_len);
        skb_reset_mac_header(skb);
 
+       if (data->inner_protocol) {
+               skb->inner_protocol = data->inner_protocol;
+               skb->inner_network_header = skb->network_header;
+               skb_set_network_header(skb, data->network_offset);
+       }
+       skb_reset_mac_len(skb);
+
        ovs_vport_send(vport, skb);
        return 0;
 }
@@ -684,7 +691,8 @@ static struct dst_ops ovs_dst_ops = {
 /* prepare_frag() is called once per (larger-than-MTU) frame; its inverse is
  * ovs_vport_output(), which is called once per fragmented packet.
  */
-static void prepare_frag(struct vport *vport, struct sk_buff *skb)
+static void prepare_frag(struct vport *vport, struct sk_buff *skb,
+                        u16 orig_network_offset)
 {
        unsigned int hlen = skb_network_offset(skb);
        struct ovs_frag_data *data;
@@ -694,6 +702,7 @@ static void prepare_frag(struct vport *vport, struct 
sk_buff *skb)
        data->vport = vport;
        data->cb = *OVS_CB(skb);
        data->inner_protocol = skb->inner_protocol;
+       data->network_offset = orig_network_offset;
        data->vlan_tci = skb->vlan_tci;
        data->vlan_proto = skb->vlan_proto;
        data->l2_len = hlen;
@@ -706,6 +715,13 @@ static void prepare_frag(struct vport *vport, struct 
sk_buff *skb)
 static void ovs_fragment(struct net *net, struct vport *vport,
                         struct sk_buff *skb, u16 mru, __be16 ethertype)
 {
+       u16 orig_network_offset = 0;
+
+       if (skb->inner_protocol) {
+               orig_network_offset = skb_network_offset(skb);
+               skb->network_header = skb->inner_network_header;
+       }
+
        if (skb_network_offset(skb) > MAX_L2_LEN) {
                OVS_NLERR(1, "L2 header too long to fragment");
                goto err;
@@ -715,7 +731,7 @@ static void ovs_fragment(struct net *net, struct vport 
*vport,
                struct dst_entry ovs_dst;
                unsigned long orig_dst;
 
-               prepare_frag(vport, skb);
+               prepare_frag(vport, skb, orig_network_offset);
                dst_init(&ovs_dst, &ovs_dst_ops, NULL, 1,
                         DST_OBSOLETE_NONE, DST_NOCOUNT);
                ovs_dst.dev = vport->dev;
@@ -735,7 +751,7 @@ static void ovs_fragment(struct net *net, struct vport 
*vport,
                        goto err;
                }
 
-               prepare_frag(vport, skb);
+               prepare_frag(vport, skb, orig_network_offset);
                memset(&ovs_rt, 0, sizeof(ovs_rt));
                dst_init(&ovs_rt.dst, &ovs_dst_ops, NULL, 1,
                         DST_OBSOLETE_NONE, DST_NOCOUNT);
-- 
1.8.3.1