Re: [Qemu-devel] [PATCH v9 01/10] net: add a new object netfilter

[Yang Hongyang]

Hi Stefan,

On 09/01/2015 10:36 PM, Stefan Hajnoczi wrote:
> On Tue, Sep 01, 2015 at 05:06:14PM +0800, Yang Hongyang wrote:
> > Add the framework for a new netfilter object and a new
> > -netfilter CLI option as a basis for the following patches.
> > Note that the new added document in qemu-options.hx indicate that
> > there's a buffer filter. This type of filter will be implemented
> > in the following patches.
>
> Adding Markus and Andreas for the command-line and QAPI perspective on
> adding a new type of object to QEMU.

I think I've already addressed Markus's comment of QAPI part on v8 :)
Thanks!

> It seems you have followed how the net subsystem adds -netdev.  I think

Yes, but for v9, it's different, we now use flat union instead of simple union
as in -netdev. According to Markus's comment.

> that approach is not the preferred way of adding new types of objects...
>
> > Signed-off-by: Yang Hongyang <address@hidden>
> > CC: Paolo Bonzini <address@hidden>
> > CC: Eric Blake <address@hidden>
> > Reviewed-by: Thomas Huth <address@hidden>
> > ---
> > v9: Add documentation of buffer filter which will be implemented later
> >      in this series.
> > ---
> >   include/net/filter.h    | 15 +++++++++++++++
> >   include/sysemu/sysemu.h |  1 +
> >   net/Makefile.objs       |  1 +
> >   net/filter.c            | 27 +++++++++++++++++++++++++++
> >   qemu-options.hx         | 21 +++++++++++++++++++++
> >   vl.c                    | 13 +++++++++++++
> >   6 files changed, 78 insertions(+)
> >   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..4242ded
> > --- /dev/null
> > +++ b/include/net/filter.h
> > @@ -0,0 +1,15 @@
> > +/*
> > + * Copyright (c) 2015 FUJITSU LIMITED
> > + *
> > + * 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 "qemu-common.h"
> > +
> > +int net_init_filters(void);
> > +
> > +#endif /* QEMU_NET_FILTER_H */
> > diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
> > index 44570d1..15d6d00 100644
> > --- a/include/sysemu/sysemu.h
> > +++ b/include/sysemu/sysemu.h
> > @@ -212,6 +212,7 @@ extern QemuOptsList qemu_chardev_opts;
> >   extern QemuOptsList qemu_device_opts;
> >   extern QemuOptsList qemu_netdev_opts;
> >   extern QemuOptsList qemu_net_opts;
> > +extern QemuOptsList qemu_netfilter_opts;
> >   extern QemuOptsList qemu_global_opts;
> >   extern QemuOptsList qemu_mon_opts;
> >
> > 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..4e40f08
> > --- /dev/null
> > +++ b/net/filter.c
> > @@ -0,0 +1,27 @@
> > +/*
> > + * Copyright (c) 2015 FUJITSU LIMITED
> > + *
> > + * 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 "net/filter.h"
> > +
> > +int net_init_filters(void)
> > +{
> > +    return 0;
> > +}
> > +
> > +QemuOptsList qemu_netfilter_opts = {
> > +    .name = "netfilter",
> > +    .implied_opt_name = "type",
> > +    .head = QTAILQ_HEAD_INITIALIZER(qemu_netfilter_opts.head),
> > +    .desc = {
> > +        /*
> > +         * no elements => accept any params
> > +         * validation will happen later
> > +         */
> > +        { /* end of list */ }
> > +    },
> > +};
>
> ...because catch-alls like this make introspection impossible.
>
> > diff --git a/qemu-options.hx b/qemu-options.hx
> > index 77f5853..f1d42a1 100644
> > --- a/qemu-options.hx
> > +++ b/qemu-options.hx
> > @@ -1991,6 +1991,27 @@ override the default configuration (@option{-net nic 
> > -net user}) which
> >   is activated if no @option{-net} options are provided.
> >   ETEXI
> >
> > +DEF("netfilter", HAS_ARG, QEMU_OPTION_netfilter,
> > +    "-netfilter buffer,id=str,netdev=str[,chain=in|out|all,interval=t]\n"
> > +    "                buffer network packets on netdev. if interval provided, will 
> > release\n"
> > +    "                packets by interval. Interval scale: microsecond\n", 
> > QEMU_ARCH_ALL)
>
> Perhaps the -object option should be used:
>
>    -object netfilter-buffer,id=str,netdev=str[,chain=in|out|all,interval=t]
>
> That is how IOThread and memory backends were recently added.
>
> They are QOM objects (see include/qom/object.h) and eliminate the need
> to write boilerplate code that adds new command-line options and
> instantiates objects.

I thought -netfilter is more obvious for an object name, -object is kind of
abstract name... but I'm not maintainer, if you think it's really need to
change to -object, I can do that.
Thanks!

> > +STEXI
> > address@hidden -netfilter 
> > buffer,address@hidden,address@hidden,address@hidden/out/all}][,address@hidden
> > +Buffer network packets on netdev @var{netdevid}.
> > +If interval @var{t} provided, will release packets by interval. Interval 
> > scale: microsecond.
> > +If interval @var{t} not provided, you have to make sure the packets can be 
> > released,
> > +either by manually remove this filter or call the release buffer API, 
> > otherwise,
> > +the packets will be buffered forever. Use with caution.
> > +
> > +chain @var{in/out/all} is an option that can be applied to any netfilter, 
> > default is @option{all}.
> > +
> > address@hidden means this filter will receive packets sent to the netdev
> > +
> > address@hidden means this filter will receive packets sent from the netdev
> > +
> > address@hidden means this filter will receive packets both sent to/from the 
> > netdev
> > +ETEXI
> > +
> >   STEXI
> >   @end table
> >   ETEXI
> > diff --git a/vl.c b/vl.c
> > index 584ca88..aee931a 100644
> > --- a/vl.c
> > +++ b/vl.c
> > @@ -75,6 +75,7 @@ int main(int argc, char **argv)
> >   #include "monitor/qdev.h"
> >   #include "sysemu/bt.h"
> >   #include "net/net.h"
> > +#include "net/filter.h"
> >   #include "net/slirp.h"
> >   #include "monitor/monitor.h"
> >   #include "ui/console.h"
> > @@ -2998,6 +2999,7 @@ int main(int argc, char **argv, char **envp)
> >       qemu_add_opts(&qemu_device_opts);
> >       qemu_add_opts(&qemu_netdev_opts);
> >       qemu_add_opts(&qemu_net_opts);
> > +    qemu_add_opts(&qemu_netfilter_opts);
> >       qemu_add_opts(&qemu_rtc_opts);
> >       qemu_add_opts(&qemu_global_opts);
> >       qemu_add_opts(&qemu_mon_opts);
> > @@ -3284,6 +3286,13 @@ int main(int argc, char **argv, char **envp)
> >                       exit(1);
> >                   }
> >                   break;
> > +            case QEMU_OPTION_netfilter:
> > +                opts = qemu_opts_parse_noisily(qemu_find_opts("netfilter"),
> > +                                               optarg, true);
> > +                if (!opts) {
> > +                    exit(1);
> > +                }
> > +                break;
> >   #ifdef CONFIG_LIBISCSI
> >               case QEMU_OPTION_iscsi:
> >                   opts = qemu_opts_parse_noisily(qemu_find_opts("iscsi"),
> > @@ -4413,6 +4422,10 @@ int main(int argc, char **argv, char **envp)
> >           exit(1);
> >       }
> >
> > +    if (net_init_filters() < 0) {
> > +        exit(1);
> > +    }
> > +
> >   #ifdef CONFIG_TPM
> >       if (tpm_init() < 0) {
> >           exit(1);
> > --
> > 1.9.1
> .

--
Thanks,
Yang.