Eelco Chaudron <[email protected]> writes:
> On 2 Jun 2021, at 18:21, Aaron Conole wrote:
>
>> Eelco Chaudron <[email protected]> writes:
>>
>>> Currently, conntrack in the kernel has an undocumented feature referred
>>> to as all-zero IP address SNAT. Basically, when a source port
>>> collision is detected during the commit, the source port will be
>>> translated to an ephemeral port. If there is no collision, no SNAT is
>>> performed.
>>>
>>> This patchset documents this behavior and adds a self-test to verify
>>> it's not changing. In addition, a datapath feature flag is added for
>>> the all-zero IP SNAT case. This will help applications on top of OVS,
>>> like OVN, to determine this feature can be used.
>>>
>>> Signed-off-by: Eelco Chaudron <[email protected]>
>>> ---
>>> v4: Added datapath support flag for all-zero SNAT.
>>> v3: Renamed NULL SNAT to all-zero IP SNAT.
>>> v2: Fixed NULL SNAT to only work in the -rpl state to be inline with
>>> OpenShift-SDN's behavior.
>>>
>>> lib/ct-dpif.c | 8 +++++++
>>> lib/ct-dpif.h | 6 +++++
>>> lib/dpif-netdev.c | 1 +
>>> lib/dpif-netlink.c | 11 +++++++++
>>> lib/dpif-provider.h | 5 ++++
>>> lib/ovs-actions.xml | 10 ++++++++
>>> ofproto/ofproto-dpif.c | 22 +++++++++++++++++-
>>> ofproto/ofproto-dpif.h | 5 +++-
>>> tests/system-kmod-macros.at | 7 ++++++
>>> tests/system-traffic.at | 46
>>> ++++++++++++++++++++++++++++++++++++++
>>> tests/system-userspace-macros.at | 10 ++++++++
>>> vswitchd/vswitch.xml | 9 +++++++
>>> 12 files changed, 138 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/lib/ct-dpif.c b/lib/ct-dpif.c
>>> index 6a5ba052d..cfc2315e3 100644
>>> --- a/lib/ct-dpif.c
>>> +++ b/lib/ct-dpif.c
>>> @@ -889,3 +889,11 @@ ct_dpif_get_timeout_policy_name(struct dpif *dpif,
>>> uint32_t tp_id,
>>> dpif, tp_id, dl_type, nw_proto, tp_name, is_generic)
>>> : EOPNOTSUPP);
>>> }
>>> +
>>> +int
>>> +ct_dpif_get_features(struct dpif *dpif, enum ct_features *features)
>>> +{
>>
>> NIT-mode:
>>
>> Are these features or capabilities? I ask because we may want to add
>> support for things like tcp loose mode, etc, and not sure if there would
>> need to be a corresponding set function (to enable / disable), and how
>> that should look. I'm okay with keeping it as-is for here and adding
>> the corresponding set function later, but it would seem strange to try
>> and "set" support for all-zero snat, etc.
>
> Guess the line between feature and capabilities is rather thin... The
> code for checking the datapath support, check_support(), is calling
> all of this features, rather than capabilities.
>
> I guess ct_zero_snat is a none configurable feature ;) But more
> seriously, I could go ahead and change the naming from feature to
> capability. As most of the configurable "features" have their own
> callback.
I guess it doesn't matter too much, but I worry about whether we start
trying to enable. Maybe we just make it unsupportable? I'm just
concerned that when we add things like tcp_loose or try to make
tcp_liberal as a configurable in the kernel DP, there could be some
confusion. Maybe it isn't too important. Okay, we can cross those
bridges when we get there.
>>> + return (dpif->dpif_class->ct_get_features
>>> + ? dpif->dpif_class->ct_get_features(dpif, features)
>>> + : EOPNOTSUPP);
>>> +}
>
> <SNIP>
>
>>> diff --git a/tests/system-userspace-macros.at
>>> b/tests/system-userspace-macros.at
>>> index 34f82cee3..9f0d38dfb 100644
>>> --- a/tests/system-userspace-macros.at
>>> +++ b/tests/system-userspace-macros.at
>>> @@ -96,6 +96,16 @@ m4_define([CHECK_CONNTRACK_FRAG_OVERLAP])
>>> #
>>> m4_define([CHECK_CONNTRACK_NAT])
>>>
>>> +# CHECK_CONNTRACK_ZEROIP_SNAT()
>>> +#
>>> +# Perform requirements checks for running conntrack all-zero IP SNAT tests.
>>> +# The userspace datapath does not support all-zero IP SNAT.
>>> +#
>>> +m4_define([CHECK_CONNTRACK_ZEROIP_SNAT],
>>> +[
>>> + AT_SKIP_IF([:])
>>> +])
>>
>> I didn't check too close, but maybe it's possible to make this check the
>> capabilities bits and then it could be extended to everywhere.
>
> I was thinking about using "ovs-appctl dpif/show-dp-features" after I
> added the features check. However none of the other test cases do
> this, so I thought there might be a reason? It might be that I need to
> configure/setup OVS to run the test command, and not sure if there is
> a nice clean way to shut down if the feature is not supported.
Okay. Maybe it's not possible in the test framework.
>>> +
>>> # CHECK_CONNTRACK_TIMEOUT()
>>> #
>>> # Perform requirements checks for running conntrack customized timeout
>>> tests.
>>> diff --git a/vswitchd/vswitch.xml b/vswitchd/vswitch.xml
>>> index 4597a215d..d8ea287d5 100644
>>> --- a/vswitchd/vswitch.xml
>>> +++ b/vswitchd/vswitch.xml
>>> @@ -6126,6 +6126,15 @@ ovs-vsctl add-port br0 p0 -- set Interface p0
>>> type=patch options:peer=p1 \
>>> True if the datapath supports OVS_ACTION_ATTR_DROP. If false,
>>> explicit drop action will not be sent to the datapath.
>>> </column>
>>> + <column name="capabilities" key="ct_zero_snat"
>>> + type='{"type": "boolean"}'>
>>> + True if the datapath supports all-zero SNAT. This is a special case
>>> + if the <code>src</code> IP address is configured as all 0's, i.e.,
>>> + <code>nat(src=0.0.0.0)</code>. In this case, when a source port
>>> + collision is detected during the commit, the source port will be
>>> + translated to an ephemeral port. If there is no collision, no SNAT
>>> + is performed.
>>> + </column>
>>> </group>
>>>
>>> <group title="Common Columns">
Acked-by: Aaron Conole <[email protected]>
_______________________________________________
dev mailing list
[email protected]
https://mail.openvswitch.org/mailman/listinfo/ovs-dev
