netdev - [PATCH net-next 7/8] openvswitch: Drop user features if old user space attempted to create datapath

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Date:	Fri, 22 Nov 2013 17:56:10 +0100
From:	Thomas Graf <tgraf@...g.ch>
To:	jesse@...ira.com, davem@...emloft.net
Cc:	dev@...nvswitch.org, netdev@...r.kernel.org, dborkman@...hat.com,
	ffusco@...hat.com, fleitner@...hat.com, eric.dumazet@...il.com,
	bhutchings@...arflare.com
Subject: [PATCH net-next 7/8] openvswitch: 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Drop user features if an outdated user space instance that does not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@...g.ch>
Reviewed-by: Daniel Borkmann <dborkman@...hat.com>
---
 include/uapi/linux/openvswitch.h | 10 +++++++++-
 net/openvswitch/datapath.c       |  9 +++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/include/uapi/linux/openvswitch.h b/include/uapi/linux/openvswitch.h
index 07ef2c3..a6863e2 100644
--- a/include/uapi/linux/openvswitch.h
+++ b/include/uapi/linux/openvswitch.h
@@ -40,7 +40,15 @@ 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
+ *     with NLM_F_REPLACE 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,
diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
index 3f1fb87..f6c1b1e 100644
--- a/net/openvswitch/datapath.c
+++ b/net/openvswitch/datapath.c
@@ -1198,6 +1198,15 @@ static int ovs_dp_create_or_update(struct sk_buff *skb, struct genl_info *info,
 		if (info->nlhdr->nlmsg_flags & NLM_F_REPLACE)
 			goto update;
 
+		/* An outdated user space instance that does not understand
+		 * the concept of user_features has attempted to create a new
+		 * datapath. Drop all user features.
+		 */
+		if (info->genlhdr->version < OVS_DP_VER_FEATURES) {
+			WARN(dp->user_features, "Dropping previously announced user features\n");
+			dp->user_features = 0;
+		}
+
 		err = -EEXIST;
 		goto err_unlock_ovs;
 	}
-- 
1.8.3.1

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