[PATCH 4.19 308/338] net: openvswitch: dont send internal clone attribute to the userspace.

Greg Kroah-Hartman
2022-04-14T14:01:53Z

From: Ilya Maximets <i.maximets@ovn.org>

[ Upstream commit 3f2a3050b4a3e7f32fc0ea3c9b0183090ae00522 ]

'OVS_CLONE_ATTR_EXEC' is an internal attribute that is used for
performance optimization inside the kernel. It's added by the kernel
while parsing user-provided actions and should not be sent during the
flow dump as it's not part of the uAPI.

The issue doesn't cause any significant problems to the ovs-vswitchd
process, because reported actions are not really used in the
application lifecycle and only supposed to be shown to a human via
ovs-dpctl flow dump. However, the action list is still incorrect
and causes the following error if the user wants to look at the
datapath flows:

# ovs-dpctl add-dp system@ovs-system
# ovs-dpctl add-flow "<flow match>" "clone(ct(commit),0)"
# ovs-dpctl dump-flows
<flow match>, packets:0, bytes:0, used:never,
actions:clone(bad length 4, expected -1 for: action0(01 00 00 00),
ct(commit),0)

With the fix:

# ovs-dpctl dump-flows
<flow match>, packets:0, bytes:0, used:never,
actions:clone(ct(commit),0)

Additionally fixed an incorrect attribute name in the comment.

Fixes: b233504033db ("openvswitch: kernel datapath clone action")
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>
Acked-by: Aaron Conole <aconole@redhat.com>
Link: https://lore.kernel.org/r/20220404104150.2865736-1-i.maximets@ovn.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/openvswitch/actions.c | 2 +-
net/openvswitch/flow_netlink.c | 4 +++-
2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
index 100cc09c100d..8b75afe41284 100644
--- a/net/openvswitch/actions.c
+++ b/net/openvswitch/actions.c
@@ -1098,7 +1098,7 @@ static int clone(struct datapath *dp, struct sk_buff *skb,
int rem = nla_len(attr);
bool dont_clone_flow_key;

- /* The first action is always 'OVS_CLONE_ATTR_ARG'. */
+ /* The first action is always 'OVS_CLONE_ATTR_EXEC'. */
clone_arg = nla_data(attr);
dont_clone_flow_key = nla_get_u32(clone_arg);
actions = nla_next(clone_arg, &rem);
diff --git a/net/openvswitch/flow_netlink.c b/net/openvswitch/flow_netlink.c
index fb69978f50ec..4413ffdc1e03 100644
--- a/net/openvswitch/flow_netlink.c
+++ b/net/openvswitch/flow_netlink.c
@@ -3173,7 +3173,9 @@ static int clone_action_to_attr(const struct nlattr *attr,
if (!start)
return -EMSGSIZE;

- err = ovs_nla_put_actions(nla_data(attr), rem, skb);
+ /* Skipping the OVS_CLONE_ATTR_EXEC that is always the first attribute. */
+ attr = nla_next(nla_data(attr), &rem);
+ err = ovs_nla_put_actions(attr, rem, skb);

if (err)
nla_nest_cancel(skb, start);
--
2.35.1