[ovs-dev] [PATCH v4 2/7] userspace: Support for push_eth and pop_eth actions

[Joe Stringer]

On 4 May 2017 at 12:51, Joe Stringer <joe at ovn.org> wrote:
> On 4 May 2017 at 11:13, Jiri Benc <jbenc at redhat.com> wrote:
>> On Thu, 4 May 2017 10:02:22 +0000, Zoltán Balogh wrote:
>>> I'm afraid the kernel would not accept that OVS_ACTION_ATTR_PUSH_ETH
>>> action in this case.
>>>
>>> Jiri, could you confirm, please?
>>
>> It would accept it and it would ignore the eth_type field. The kernel
>> does not verify whether netlink attributes are longer than they should
>> be. It just accepts such attributes and silently ignores the excessive
>> data.
>
> Really? Previously the OVS usage of netlink always validated that
> netlink attributes are exactly as long as expected and that there's no
> trailing data.

With a glance at __ovs_nla_copy_actions(), this is also true for
OVS_ACTION_ATTR_PUSH_ETH.