RE: [PATCH V8 1/6] qapi/net: Add IPFlowSpec and QMP command for COLO passthrough

["Zhang, Chen" <chen.zhang@intel.com>]

> -----Original Message-----
> From: Markus Armbruster <armbru@redhat.com>
> Sent: Tuesday, June 15, 2021 10:43 PM
> To: Zhang, Chen <chen.zhang@intel.com>
> Cc: Jason Wang <jasowang@redhat.com>; qemu-dev <qemu-
> devel@nongnu.org>; Eric Blake <eblake@redhat.com>; Dr. David Alan
> Gilbert <dgilbert@redhat.com>; Daniel P.Berrangé <berrange@redhat.com>;
> Gerd Hoffmann <kraxel@redhat.com>; Li Zhijian <lizhijian@cn.fujitsu.com>;
> Lukas Straub <lukasstraub2@web.de>; Zhang Chen <zhangckid@gmail.com>
> Subject: Re: [PATCH V8 1/6] qapi/net: Add IPFlowSpec and QMP command
> for COLO passthrough
> 
> Zhang Chen <chen.zhang@intel.com> writes:
> 
> > Since the real user scenario does not need COLO to monitor all traffic.
> > Add colo-passthrough-add and colo-passthrough-del to maintain a COLO
> > network passthrough list. Add IPFlowSpec struct for all QMP commands.
> > All the fields of IPFlowSpec are optional.
> >
> > Signed-off-by: Zhang Chen <chen.zhang@intel.com>
> > ---
> 
> The QAPI schema looks good to me, but the interface documentation is still
> not quite clear enough.  To make progress, I'm going to make concrete
> suggestions wherever I can despite being quite clueless about the subject
> matter.  Risks me writing something that's clearer, but wrong.  Keep that in
> mind, please.
> 
> >  net/net.c     | 10 +++++++
> >  qapi/net.json | 74
> > +++++++++++++++++++++++++++++++++++++++++++++++++++
> >  2 files changed, 84 insertions(+)
> >
> > diff --git a/net/net.c b/net/net.c
> > index 76bbb7c31b..f913e97983 100644
> > --- a/net/net.c
> > +++ b/net/net.c
> > @@ -1195,6 +1195,16 @@ void qmp_netdev_del(const char *id, Error
> **errp)
> >      }
> >  }
> >
> > +void qmp_colo_passthrough_add(IPFlowSpec *spec, Error **errp) {
> > +    /* TODO implement setup passthrough rule */ }
> > +
> > +void qmp_colo_passthrough_del(IPFlowSpec *spec, Error **errp) {
> > +    /* TODO implement delete passthrough rule */ }
> > +
> >  static void netfilter_print_info(Monitor *mon, NetFilterState *nf)  {
> >      char *str;
> > diff --git a/qapi/net.json b/qapi/net.json index
> > 7fab2e7cd8..91f2e1495a 100644
> > --- a/qapi/net.json
> > +++ b/qapi/net.json
> > @@ -7,6 +7,7 @@
> >  ##
> >
> >  { 'include': 'common.json' }
> > +{ 'include': 'sockets.json' }
> >
> >  ##
> >  # @set_link:
> > @@ -696,3 +697,76 @@
> >  ##
> >  { 'event': 'FAILOVER_NEGOTIATED',
> >    'data': {'device-id': 'str'} }
> > +
> > +##
> > +# @IPFlowSpec:
> > +#
> > +# IP flow specification.
> > +#
> > +# @protocol: Transport layer protocol like TCP/UDP, etc. The protocol is
> the
> > +#            string instead of enum, because it can be passed to
> getprotobyname(3)
> > +#            and avoid duplication with /etc/protocols.
> 
> The rationale is good, but it doesn't really belong into the interface
> documentation.  Suggest:
> 
>    # @protocol: Transport layer protocol like TCP/UDP, etc.  This will be
>    #            passed to getprotobyname(3).
> 

OK.

> 
> > +#
> > +# @object-name: The @object-name means packet handler in Qemu.
> Because not
> > +#               all the network packet must pass the colo-compare module,
> > +#               the net-filters are same situation. There modules attach to
> > +#               netdev or chardev to work, VM can run multiple modules
> > +#               at the same time. So it needs the object-name to set
> > +#               the effective module.
> 
> I still don't understand this, and I'm too ignorant of COLO and networking to
> suggest improvements.

Let me use qemu boot parameter to clear it.
For colo-compare, it needs chardev as the source to handle network packet.
-object colo-compare,id=comp0,primary_in=chardev-input0,secondary_in=chardev-input1,outdev=chardev-output0,iothread=iothread0.

For net filters, it needs attached on netdev.
-object filter-redirector,id=red0,netdev=hn0,queue=rx,outdev=chardev-output1
-object filter-mirror,id=mirror0,netdev=hn0,queue=rx,outdev=chardev-output2

And we can use -chardev socket combine the filter and the colo-compare.

Back to the @object-name, One guest maybe have multi colo-compare as the same time, with different object name from different source.
So we need assign the IPFlowSpec to one object as the handler. Same as the net-filters.
Each object instance has its own passthrough list.


> 
> Jason or David, perhaps?
> 
> > +#
> > +# @source: Source address and port.
> > +#
> > +# @destination: Destination address and port.
> > +#
> > +# Since: 6.1
> > +##
> > +{ 'struct': 'IPFlowSpec',
> > +  'data': { '*protocol': 'str', '*object-name': 'str',
> > +    '*source': 'InetSocketAddressBase',
> > +    '*destination': 'InetSocketAddressBase' } }
> > +
> > +##
> > +# @colo-passthrough-add:
> > +#
> > +# Add passthrough entry IPFlowSpec to the COLO-compare instance.
> > +# The protocol and source/destination IP/ports are optional. if the
> > +user # only inputs part of the information, this will match all traffic.
> 
> Actually, all arguments are optional.
> 
> Suggest:
> 
>    # Add an entry to the COLO network passthrough list.
>    # Absent protocol, host addresses and ports match anything.
> 
> If there is more than one such list, then "to a COLO network passthrough list"
> instead.

Yes, more than one list.

> 
> Still missing then: meaning of absent @object-name.  Does it select the COLO
> network passthrough list, perhaps?

Yes, Please see the explanation above. Each object instance has its own passthrough list.

> 
> > +#
> > +# Returns: Nothing on success
> > +#
> > +# Since: 6.1
> > +#
> > +# Example:
> > +#
> > +# -> { "execute": "colo-passthrough-add",
> > +#      "arguments": { "protocol": "tcp", "object-name": "object0",
> > +#      "source": {"host": "192.168.1.1", "port": "1234"},
> > +#      "destination": {"host": "192.168.1.2", "port": "4321"} } }
> > +# <- { "return": {} }
> > +#
> > +##
> > +{ 'command': 'colo-passthrough-add', 'boxed': true,
> > +     'data': 'IPFlowSpec' }
> > +
> > +##
> > +# @colo-passthrough-del:
> > +#
> > +# Delete passthrough entry IPFlowSpec to the COLO-compare instance.
> > +# The protocol and source/destination IP/ports are optional. if the
> > +user # only inputs part of the information, this will match all traffic.
> 
> I suspect this command doesn't actually match traffic, it matches entries
> added with colo-passthrough-add.

Yes.

> 
> Can it delete more than one such entry?
> 

Currently no, but it easy to match one more entry to delete.

> Suggest:
> 
>    # Delete an entry from the COLO network passthrough list.
> 
> and then explain how the command arguments select entries.

Search the object's passthrough list, if find same entry,  delete it.

Thanks
Chen

> 
> > +#
> > +# Returns: Nothing on success
> > +#
> > +# Since: 6.1
> > +#
> > +# Example:
> > +#
> > +# -> { "execute": "colo-passthrough-del",
> > +#      "arguments": { "protocol": "tcp", "object-name": "object0",
> > +#      "source": {"host": "192.168.1.1", "port": "1234"},
> > +#      "destination": {"host": "192.168.1.2", "port": "4321"} } }
> > +# <- { "return": {} }
> > +#
> > +##
> > +{ 'command': 'colo-passthrough-del', 'boxed': true,
> > +     'data': 'IPFlowSpec' }