Re: [Qemu-devel] [PATCH v11 02/12] init/cleanup of netfilter object

[Markus Armbruster]

Yang Hongyang <address@hidden> writes:

> On 09/24/2015 04:41 PM, Markus Armbruster wrote:
>> Yang Hongyang <address@hidden> writes:
>>
>>> Add a netfilter object based on QOM.
>>>
>>> A netfilter is attached to a netdev, captures all network packets
>>> that pass through the netdev. When we delete the netdev, we also
>>> delete the netfilter object attached to it, because if the netdev is
>>> removed, the filter which attached to it is useless.
>>>
>>> QTAILQ_ENTRY next used by netdev, filter belongs to the specific netdev is
>>> in this queue.
>>
>> I don't get this paragraph.  Not sure it's needed.
>>
>>> Also init delayed object after net_init_clients, because netfilters need
>>> to be initialized after net clients initialized.
>>
>> A paragraph starting with "Also" in a commit message is a pretty good
>> sign the patch should be split :)
>>
>>>
>>> Signed-off-by: Yang Hongyang <address@hidden>
>>> ---
>>> v11: no need to free nf->netdev_id, it will be auto freeed while object 
>>> deleted
>>>       remove global_list net_filters, will add back when needed
>>> v10: use QOM for netfilter
>>> v9: use flat union instead of simple union in QAPI schema
>>> v8: include vhost_net header
>>> v7: add check for vhost
>>>      fix error propagate bug
>>> v6: add multiqueue support (net_filter_init1)
>>> v5: remove model from NetFilterState
>>>      add a sent_cb param to receive_iov API
>>> ---
>>>   include/net/filter.h    |  60 +++++++++++++++++++++
>>>   include/net/net.h       |   1 +
>>>   include/qemu/typedefs.h |   1 +
>>>   net/Makefile.objs       |   1 +
>>>   net/filter.c            | 138 
>>> ++++++++++++++++++++++++++++++++++++++++++++++++
>>>   net/net.c               |   7 +++
>>>   qapi-schema.json        |  18 +++++++
>>>   vl.c                    |  13 ++---
>>>   8 files changed, 233 insertions(+), 6 deletions(-)
>>>   create mode 100644 include/net/filter.h
>>>   create mode 100644 net/filter.c
>>>
>>> diff --git a/include/net/filter.h b/include/net/filter.h
>>> new file mode 100644
>>> index 0000000..226f2f7
>>> --- /dev/null
>>> +++ b/include/net/filter.h
>>> @@ -0,0 +1,60 @@
>>> +/*
>>> + * Copyright (c) 2015 FUJITSU LIMITED
>>> + * Author: Yang Hongyang <address@hidden>
>>> + *
>>> + * This work is licensed under the terms of the GNU GPL, version 2 or
>>> + * later.  See the COPYING file in the top-level directory.
>>> + */
>>> +
>>> +#ifndef QEMU_NET_FILTER_H
>>> +#define QEMU_NET_FILTER_H
>>> +
>>> +#include "qom/object.h"
>>> +#include "qemu-common.h"
>>> +#include "qemu/typedefs.h"
>>> +#include "net/queue.h"
>>> +
>>> +#define TYPE_NETFILTER "netfilter"
>>> +#define NETFILTER(obj) \
>>> +    OBJECT_CHECK(NetFilterState, (obj), TYPE_NETFILTER)
>>> +#define NETFILTER_GET_CLASS(obj) \
>>> +    OBJECT_GET_CLASS(NetFilterClass, (obj), TYPE_NETFILTER)
>>> +#define NETFILTER_CLASS(klass) \
>>> +    OBJECT_CLASS_CHECK(NetFilterClass, (klass), TYPE_NETFILTER)
>>> +
>>> +typedef void (FilterSetup) (NetFilterState *nf, Error **errp);
>>> +typedef void (FilterCleanup) (NetFilterState *nf);
>>> +/*
>>> + * Return:
>>> + *   0: finished handling the packet, we should continue
>>> + *   size: filter stolen this packet, we stop pass this packet further
>>> + */
>>> +typedef ssize_t (FilterReceiveIOV)(NetFilterState *nc,
>>> +                                   NetClientState *sender,
>>> +                                   unsigned flags,
>>> +                                   const struct iovec *iov,
>>> +                                   int iovcnt,
>>> +                                   NetPacketSent *sent_cb);
>>> +
>>> +struct NetFilterClass {
>>> +    ObjectClass parent_class;
>>> +
>>> +    FilterSetup *setup;
>>> +    FilterCleanup *cleanup;
>>> +    FilterReceiveIOV *receive_iov;
>>> +};
>>> +typedef struct NetFilterClass NetFilterClass;
>>
>> Not splitting the declaration is more concise:
>>
>>      typedef struct {
>>          ObjectClass parent_class;
>>          FilterSetup *setup;
>>          FilterCleanup *cleanup;
>>          FilterReceiveIOV *receive_iov;
>>      } NetFilterClass;
>>
>> Are any of the methods optional?  If yes, please add suitable comments.
>>
>>> +
>>> +
>>> +struct NetFilterState {
>>> +    /* private */
>>> +    Object parent;
>>> +
>>> +    /* protected */
>>> +    char *netdev_id;
>>> +    NetClientState *netdev;
>>> +    NetFilterChain chain;
>>> +    QTAILQ_ENTRY(NetFilterState) next;
>>> +};
>>> +
>>> +#endif /* QEMU_NET_FILTER_H */
>>> diff --git a/include/net/net.h b/include/net/net.h
>>> index 6a6cbef..36e5fab 100644
>>> --- a/include/net/net.h
>>> +++ b/include/net/net.h
>>> @@ -92,6 +92,7 @@ struct NetClientState {
>>>       NetClientDestructor *destructor;
>>>       unsigned int queue_index;
>>>       unsigned rxfilter_notify_enabled:1;
>>> +    QTAILQ_HEAD(, NetFilterState) filters;
>>>   };
>>>
>>>   typedef struct NICState {
>>> diff --git a/include/qemu/typedefs.h b/include/qemu/typedefs.h
>>> index f8a9dd6..2c0648f 100644
>>> --- a/include/qemu/typedefs.h
>>> +++ b/include/qemu/typedefs.h
>>> @@ -45,6 +45,7 @@ typedef struct Monitor Monitor;
>>>   typedef struct MouseTransformInfo MouseTransformInfo;
>>>   typedef struct MSIMessage MSIMessage;
>>>   typedef struct NetClientState NetClientState;
>>> +typedef struct NetFilterState NetFilterState;
>>>   typedef struct NICInfo NICInfo;
>>>   typedef struct PcGuestInfo PcGuestInfo;
>>>   typedef struct PCIBridge PCIBridge;
>>> diff --git a/net/Makefile.objs b/net/Makefile.objs
>>> index ec19cb3..914aec0 100644
>>> --- a/net/Makefile.objs
>>> +++ b/net/Makefile.objs
>>> @@ -13,3 +13,4 @@ common-obj-$(CONFIG_HAIKU) += tap-haiku.o
>>>   common-obj-$(CONFIG_SLIRP) += slirp.o
>>>   common-obj-$(CONFIG_VDE) += vde.o
>>>   common-obj-$(CONFIG_NETMAP) += netmap.o
>>> +common-obj-y += filter.o
>>> diff --git a/net/filter.c b/net/filter.c
>>> new file mode 100644
>>> index 0000000..3b810c8
>>> --- /dev/null
>>> +++ b/net/filter.c
>>> @@ -0,0 +1,138 @@
>>> +/*
>>> + * Copyright (c) 2015 FUJITSU LIMITED
>>> + * Author: Yang Hongyang <address@hidden>
>>> + *
>>> + * This work is licensed under the terms of the GNU GPL, version 2 or
>>> + * later.  See the COPYING file in the top-level directory.
>>> + */
>>> +
>>> +#include "qemu-common.h"
>>> +#include "qapi/qmp/qerror.h"
>>> +#include "qemu/error-report.h"
>>> +
>>> +#include "net/filter.h"
>>> +#include "net/net.h"
>>> +#include "net/vhost_net.h"
>>> +#include "qom/object_interfaces.h"
>>> +
>>> +static char *netfilter_get_netdev_id(Object *obj, Error **errp)
>>> +{
>>> +    NetFilterState *nf = NETFILTER(obj);
>>> +
>>> +    return g_strdup(nf->netdev_id);
>>> +}
>>> +
>>> +static void netfilter_set_netdev_id(Object *obj, const char *str, Error 
>>> **errp)
>>> +{
>>> +    NetFilterState *nf = NETFILTER(obj);
>>> +
>>> +    nf->netdev_id = g_strdup(str);
>>> +}
>>> +
>>> +static int netfilter_get_chain(Object *obj, Error **errp G_GNUC_UNUSED)
>>> +{
>>> +    NetFilterState *nf = NETFILTER(obj);
>>> +    return nf->chain;
>>> +}
>>> +
>>> +static void netfilter_set_chain(Object *obj, int chain, Error **errp)
>>> +{
>>> +    NetFilterState *nf = NETFILTER(obj);
>>> +    nf->chain = chain;
>>> +}
>>> +
>>> +static void netfilter_init(Object *obj)
>>> +{
>>> +    object_property_add_str(obj, "netdev",
>>> +                            netfilter_get_netdev_id, 
>>> netfilter_set_netdev_id,
>>> +                            NULL);
>>> +    object_property_add_enum(obj, "chain", "NetFilterChain",
>>> +                             NetFilterChain_lookup,
>>> +                             netfilter_get_chain, netfilter_set_chain,
>>> +                             NULL);
>>> +}
>>> +
>>> +static void netfilter_finalize(Object *obj)
>>> +{
>>> +    NetFilterState *nf = NETFILTER(obj);
>>> +    NetFilterClass *nfc = NETFILTER_GET_CLASS(obj);
>>> +
>>> +    if (nfc->cleanup) {
>>
>> Is ->cleanup optional?
>
> Yes, it's optional, as well as setup, if a concrete filter do
> not have things to setup/cleanup.

Please document that in NetFilterClass.

>>> +        nfc->cleanup(nf);
>>> +    }
>>> +
>>> +    if (nf->netdev && !QTAILQ_EMPTY(&nf->netdev->filters)) {
>>
>> How can nf->netdev be null?
>>
>> How can nf->netdev->filters be empty?
>
> When object initialize failed. for example, in netfilter_complete
> no nf->netdev_id provided, object initialize will fail, and the
> netfilter_finalize will be called, at the mean time,
> nf->netdev is null, and nf->netdev->filters is empty.

Okay.

>>> +        QTAILQ_REMOVE(&nf->netdev->filters, nf, next);
>>> +    }
>>> +}
>>
>> Putting netfilter_finalize() after netfilter_complete() would be easier
>> to understand, because then destruction follows creation.
>>
>>> +
>>> +static void netfilter_complete(UserCreatable *uc, Error **errp)
>>> +{
>>> +    NetFilterState *nf = NETFILTER(uc);
>>> +    NetClientState *ncs[MAX_QUEUE_NUM];
>>> +    NetFilterClass *nfc = NETFILTER_GET_CLASS(uc);
>>> +    int queues;
>>> +    Error *local_err = NULL;
>>> +
>>> +    if (!nf->netdev_id) {
>>> +        error_setg(errp, "Parameter 'netdev' is required");
>>> +        return;
>>> +    }
>>> +
>>> +    queues = qemu_find_net_clients_except(nf->netdev_id, ncs,
>>> +                                          NET_CLIENT_OPTIONS_KIND_NIC,
>>> +                                          MAX_QUEUE_NUM);
>>> +    if (queues < 1) {
>>> +        error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "netdev",
>>> +                   "a network backend id");
>>> +        return;
>>> +    } else if (queues > 1) {
>>> +        error_setg(errp, "Multi queue is not supported");
>>
>> We spell this multiqueue elsewhere.
>>
>> Since you're only interested in a single queue, you could save stack
>> space by making ncs[] just one element large.  Not worth it if you
>> intend to support multiqueue soon.
>
> We will support multiqueue soon.
>
>>
>>> +        return;
>>> +    }
>>> +
>>> +    if (get_vhost_net(ncs[0])) {
>>> +        error_setg(errp, "Vhost is not supported");
>>> +        return;
>>> +    }
>>> +
>>> +    nf->netdev = ncs[0];
>>> +
>>> +    if (nfc->setup) {
>>
>> Is ->setup optional?
>
> Yes, as said earlier.
>
>>
>>> +        nfc->setup(nf, &local_err);
>>> +        if (local_err) {
>>> +            error_propagate(errp, local_err);
>>> +            return;
>>> +        }
>>> +    }
>>> +    QTAILQ_INSERT_TAIL(&nf->netdev->filters, nf, next);
>>
>> I think I'd create netdev functions to add and remove filters, so the
>> filter code doesn't have to modify the netdev state.  Right now,
>> NetClientState member filters is initialized in net.c, but modified
>> here.  But I'm not the net maintainer :)
>>
>>> +}
>>> +
>>> +static void netfilter_class_init(ObjectClass *oc, void *data)
>>> +{
>>> +    UserCreatableClass *ucc = USER_CREATABLE_CLASS(oc);
>>> +
>>> +    ucc->complete = netfilter_complete;
>>> +}
>>> +
>>> +static const TypeInfo netfilter_info = {
>>> +    .name = TYPE_NETFILTER,
>>> +    .parent = TYPE_OBJECT,
>>> +    .abstract = true,
>>> +    .class_size = sizeof(NetFilterClass),
>>> +    .class_init = netfilter_class_init,
>>> +    .instance_size = sizeof(NetFilterState),
>>> +    .instance_init = netfilter_init,
>>> +    .instance_finalize = netfilter_finalize,
>>> +    .interfaces = (InterfaceInfo[]) {
>>> +        { TYPE_USER_CREATABLE },
>>> +        { }
>>> +    }
>>> +};
>>> +
>>> +static void register_types(void)
>>> +{
>>> +    type_register_static(&netfilter_info);
>>> +}
>>> +
>>> +type_init(register_types);
[...]
>>> diff --git a/qapi-schema.json b/qapi-schema.json
>>> index 2bada60..546500a 100644
>>> --- a/qapi-schema.json
>>> +++ b/qapi-schema.json
>>> @@ -2551,6 +2551,24 @@
>>>       'opts': 'NetClientOptions' } }
>>>
>>>   ##
>>> +# @NetFilterChain
>>> +#
>>> +# netfilter chain, a netfilter is attached to a netdev, captures the
>>> +# network packets of the netdev.
>>> +#
>>> +# @all: the filter will receive packets both sent to/from the netdev, this
>>> +#       is the default chain.
>>> +#
>>> +# @in: the filter will receive packets sent to the netdev.
>>> +#
>>> +# @out: the filter will receive packets sent from the netdev.
>>
>> Uh, inhowfar is this a "chain"?  As far as I can tell, it specifies
>> whether a netfilter is attached to the transmit queue, the receive
>> queue, or both.
>
> netback's input chain or output chain, queue is mostly like a word that
> related to the code implementation? English is not my first language, so
> I'm not sure about this.

Don't worry, we'll get the language polished together :)

In PATCH 9, I learned how this is to be used:

    @item -object 
filter-buffer,address@hidden,address@hidden,address@hidden|in|out}][,address@hidden

    Buffer network packets on netdev @var{netdevid}.
[...]
    chain @var{all|in|out} is an option that can be applied to any netfilter, 
default is @option{all}.

    @option{all} means this filter will receive packets both sent to/from the 
netdev

    @option{in} means this filter will receive packets sent to the netdev

    @option{out} means this filter will receive packets sent from the netdev

In that context, "chain" makes more sense.  I'd still call it "queue".
Precedence: -netdev parameter "queues".  If I understand correctly,
queues=N asks for N rx and tx queues.  A filter would either apply to
all N rx queues, all N tx queues, or all 2*N queues.  Correct?

[...]