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

[Jason Wang]

On 09/24/2015 07:52 PM, Markus Armbruster wrote:
> 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?
>
> [...]

Yes.