datapath: Drop user features if old user space attempted to create datapath

Drop user features if an outdated user space instance that does not
understand the concept of user_features attempted to create a new
datapath.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Reviewed-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>

diff --git a/datapath/datapath.c b/datapath/datapath.c
index 08562a3..0714a99 100644 (file)
--- a/datapath/datapath.c
+++ b/datapath/datapath.c
@@ -1153,6 +1153,18 @@ static struct datapath *lookup_datapath(struct net *net,
        return dp ? dp : ERR_PTR(-ENODEV);
 }
 
+static void ovs_dp_reset_user_features(struct sk_buff *skb, struct genl_info *info)
+{
+       struct datapath *dp;
+
+       dp = lookup_datapath(sock_net(skb->sk), info->userhdr, info->attrs);
+       if (!dp)
+               return;
+
+       WARN(dp->user_features, "Dropping previously announced user features\n");
+       dp->user_features = 0;
+}
+
 static void ovs_dp_change(struct datapath *dp, struct nlattr **a)
 {
        if (a[OVS_DP_ATTR_USER_FEATURES])
@@ -1219,6 +1231,15 @@ static int ovs_dp_cmd_new(struct sk_buff *skb, struct genl_info *info)
                if (err == -EBUSY)
                        err = -EEXIST;
 
+               if (err == -EEXIST) {
+                       /* An outdated user space instance that does not understand
+                        * the concept of user_features has attempted to create a new
+                        * datapath and is likely to reuse it. Drop all user features.
+                        */
+                       if (info->genlhdr->version < OVS_DP_VER_FEATURES)
+                               ovs_dp_reset_user_features(skb, info);
+               }
+
                goto err_destroy_ports_array;
        }
 

diff --git a/include/linux/openvswitch.h b/include/linux/openvswitch.h
index 585fa63..5137c2f 100644 (file)
--- a/include/linux/openvswitch.h
+++ b/include/linux/openvswitch.h
@@ -60,7 +60,15 @@ struct ovs_header {
 
 #define OVS_DATAPATH_FAMILY  "ovs_datapath"
 #define OVS_DATAPATH_MCGROUP "ovs_datapath"
-#define OVS_DATAPATH_VERSION 0x1
+
+/* V2:
+ *   - API users are expected to provide OVS_DP_ATTR_USER_FEATURES
+ *     when creating the datapath.
+ */
+#define OVS_DATAPATH_VERSION 2
+
+/* First OVS datapath version to support features */
+#define OVS_DP_VER_FEATURES 2
 
 enum ovs_datapath_cmd {
        OVS_DP_CMD_UNSPEC,