Re: [Qemu-devel] [PATCH] net/filter-redirector:Add filter-redirector

[Jason Wang <jasowang@redhat.com>]

On 02/05/2016 02:50 PM, Zhang Chen wrote:
> From: ZhangChen <zhangchen.fnst@cn.fujitsu.com>
>
> Filter-redirector is a netfilter plugin.
> It gives qemu the ability to redirect net packet.
> redirector can redirect filter's net packet to outdev.
> and redirect indev's packet to filter.
>
>                              filter
>                                +
>                                |
>                                |
>               redirector       |
>                +-------------------------+
>                |               |         |
>                |               |         |
>                |               |         |
>   indev +----------------+     +---------------->  outdev
>                |         |               |
>                |         |               |
>                |         |               |
>                +-------------------------+
>                          |
>                          |
>                          v
>                       filter
>
> usage:
>
> -netdev tap,id=hn0
> -chardev socket,id=s0,host=ip_primary,port=X,server,nowait
> -chardev socket,id=s1,host=ip_primary,port=Y,server,nowait
> -filter-redirector,id=r0,netdev=hn0,queue=tx/rx/all,indev=s0,outdev=s1
>
> Signed-off-by: ZhangChen <zhangchen.fnst@cn.fujitsu.com>
> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
> ---

Thanks a lot for the patch. Like mirror, let's design a unit-test for
this. And what's more, is there any chance to unify the codes? (At least
parts of the codes could be reused).

>  net/Makefile.objs       |   1 +
>  net/filter-redirector.c | 245 ++++++++++++++++++++++++++++++++++++++++++++++++
>  qemu-options.hx         |   6 ++
>  vl.c                    |   3 +-
>  4 files changed, 254 insertions(+), 1 deletion(-)
>  create mode 100644 net/filter-redirector.c
>
> diff --git a/net/Makefile.objs b/net/Makefile.objs
> index 5fa2f97..f4290a5 100644
> --- a/net/Makefile.objs
> +++ b/net/Makefile.objs
> @@ -15,3 +15,4 @@ common-obj-$(CONFIG_VDE) += vde.o
>  common-obj-$(CONFIG_NETMAP) += netmap.o
>  common-obj-y += filter.o
>  common-obj-y += filter-buffer.o
> +common-obj-y += filter-redirector.o
> diff --git a/net/filter-redirector.c b/net/filter-redirector.c
> new file mode 100644
> index 0000000..364e463
> --- /dev/null
> +++ b/net/filter-redirector.c
> @@ -0,0 +1,245 @@
> +/*
> + * Copyright (c) 2016 HUAWEI TECHNOLOGIES CO., LTD.
> + * Copyright (c) 2016 FUJITSU LIMITED
> + * Copyright (c) 2016 Intel Corporation
> + *
> + * Author: Zhang Chen <zhangchen.fnst@cn.fujitsu.com>
> + *
> + * 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 "net/filter.h"
> +#include "net/net.h"
> +#include "qemu-common.h"
> +#include "qapi/qmp/qerror.h"
> +#include "qapi-visit.h"
> +#include "qom/object.h"
> +#include "qemu/main-loop.h"
> +#include "qemu/error-report.h"
> +#include "trace.h"
> +#include "sysemu/char.h"
> +#include "qemu/iov.h"
> +#include "qemu/sockets.h"
> +
> +#define FILTER_REDIRECTOR(obj) \
> +    OBJECT_CHECK(RedirectorState, (obj), TYPE_FILTER_REDIRECTOR)
> +
> +#define TYPE_FILTER_REDIRECTOR "filter-redirector"
> +#define REDIRECT_HEADER_LEN sizeof(uint32_t)
> +
> +typedef struct RedirectorState {
> +    NetFilterState parent_obj;
> +    NetQueue *incoming_queue;/* guest normal net queue */

The comment looks unless and maybe even wrong when queue=rx?

> +    char *indev;
> +    char *outdev;
> +    CharDriverState *chr_in;
> +    CharDriverState *chr_out;
> +} RedirectorState;
> +
> +static ssize_t filter_redirector_send(NetFilterState *nf,
> +                                   const struct iovec *iov,
> +                                   int iovcnt)
> +{
> +    RedirectorState *s = FILTER_REDIRECTOR(nf);
> +    ssize_t ret = 0;
> +    ssize_t size = 0;
> +    uint32_t len =  0;
> +    char *buf;
> +
> +    size = iov_size(iov, iovcnt);
> +    len = htonl(size);
> +    if (!size) {
> +        return 0;
> +    }
> +
> +    buf = g_malloc0(size);
> +    iov_to_buf(iov, iovcnt, 0, buf, size);
> +    ret = qemu_chr_fe_write_all(s->chr_out, (uint8_t *)&len, sizeof(len));
> +    if (ret < 0) {

Similar to mirror, need check the return value against sizeof(len). And
the code could be simplified with something like:

goto out;

...

out:
    g_free(buf);
    return ret;

And you can see another advantages of unifying the codes here, avoid
duplicating bugx/fixes.

> +        g_free(buf);
> +        return ret;
> +    }
> +
> +    ret = qemu_chr_fe_write_all(s->chr_out, (uint8_t *)buf, size);
> +    g_free(buf);
> +    return ret;
> +}
> +
> +static ssize_t filter_redirector_receive_iov(NetFilterState *nf,
> +                                         NetClientState *sender,
> +                                         unsigned flags,
> +                                         const struct iovec *iov,
> +                                         int iovcnt,
> +                                         NetPacketSent *sent_cb)
> +{
> +    RedirectorState *s = FILTER_REDIRECTOR(nf);
> +    ssize_t ret = 0;
> +
> +    if (s->chr_out) {
> +        ret = filter_redirector_send(nf, iov, iovcnt);
> +        if (ret < 0) {
> +            error_report("filter_redirector_send failed");
> +        }
> +    }
> +    return iov_size(iov, iovcnt);
> +}
> +
> +static void filter_redirector_cleanup(NetFilterState *nf)
> +{
> +    RedirectorState *s = FILTER_REDIRECTOR(nf);
> +
> +    if (s->chr_in) {
> +        qemu_chr_fe_release(s->chr_in);

release but no claim?

> +    }
> +    if (s->chr_out) {
> +        qemu_chr_fe_release(s->chr_out);
> +    }
> +}
> +
> +static int redirector_chr_can_read(void *opaque)
> +{
> +    return REDIRECT_HEADER_LEN;
> +}
> +
> +static void redirector_chr_read(void *opaque, const uint8_t *buf, int size)
> +{
> +    NetFilterState *nf = opaque;
> +    RedirectorState *s = FILTER_REDIRECTOR(nf);
> +    uint32_t len;
> +    ssize_t ret = 0;
> +    uint8_t *recv_buf;
> +
> +    if (size != REDIRECT_HEADER_LEN) {
> +        // FIXME: do something else

This is not packet corruption since I believe you want tcp socket here
which is doing byte stream. Need some logic to prepare to wait for all
the bytes for length is received.

Though sub-optimal (since it uses usleep() which may block iothread),
maybe you could just do a for simplicity:

qemu_chr_fe_read_all(s->chr_in, recv_buf, sizeof(len));

If you wish, you can have a look at socket backend (net_socket_send) who
has a better solution for this.
> +        error_report("packet is corruption, drop it");
> +        return;
> +    }
> +    memcpy(&len, buf, sizeof(len));
> +    len = ntohl(len);
> +
> +    if (len > 0 && len < NET_BUFSIZE) {
> +        recv_buf = g_malloc0(len);

Looks like g_malloc() is sufficient here.

> +        ret = qemu_chr_fe_read_all(s->chr_in, recv_buf, len);
> +        if (ret != len) {
> +            error_report("filter-redirector recv buf failed");
> +            g_free(recv_buf);
> +            return;
> +        }
> +
> +        ret = qemu_net_queue_send(s->incoming_queue, nf->netdev,
> +                            0, (const uint8_t *)recv_buf, len, NULL);
> +        g_free(recv_buf);
> +        if (ret < 0) {
> +            error_report("filter-redirector out to guest failed");

"guest" is inaccurate here, what if queue=rx?

> +        }
> +    } else {
> +        error_report("filter-redirector recv len failed");
> +    }
> +}
> +
> +static void filter_redirector_setup(NetFilterState *nf, Error **errp)
> +{
> +    RedirectorState *s = FILTER_REDIRECTOR(nf);
> +
> +    if (!s->indev && !s->outdev) {
> +        error_setg(errp, "filter redirector needs 'indev' or "
> +                "'outdev' at least one property set");
> +        return;
> +    }
> +
> +    if (s->indev) {
> +        s->chr_in = qemu_chr_find(s->indev);
> +        if (s->chr_in == NULL) {
> +            error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND,
> +                      "IN Device '%s' not found", s->indev);
> +            return;
> +        }
> +
> +        qemu_chr_add_handlers(s->chr_in, redirector_chr_can_read,
> +                              redirector_chr_read, NULL, nf);
> +    }
> +
> +    if (s->outdev) {
> +        s->chr_out = qemu_chr_find(s->outdev);
> +        if (s->chr_out == NULL) {
> +            error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND,
> +                      "OUT Device '%s' not found", s->outdev);
> +            return;
> +        }
> +    }
> +    s->incoming_queue = qemu_new_net_queue(qemu_netfilter_pass_to_next, nf);
> +}
> +
> +static void filter_redirector_class_init(ObjectClass *oc, void *data)
> +{
> +    NetFilterClass *nfc = NETFILTER_CLASS(oc);
> +
> +    nfc->setup = filter_redirector_setup;
> +    nfc->cleanup = filter_redirector_cleanup;
> +    nfc->receive_iov = filter_redirector_receive_iov;
> +}
> +
> +static char *filter_redirector_get_indev(Object *obj, Error **errp)
> +{
> +    RedirectorState *s = FILTER_REDIRECTOR(obj);
> +
> +    return g_strdup(s->indev);
> +}
> +
> +static void
> +filter_redirector_set_indev(Object *obj, const char *value, Error **errp)
> +{
> +    RedirectorState *s = FILTER_REDIRECTOR(obj);
> +
> +    g_free(s->indev);
> +    s->indev = g_strdup(value);
> +}
> +
> +static char *filter_redirector_get_outdev(Object *obj, Error **errp)
> +{
> +    RedirectorState *s = FILTER_REDIRECTOR(obj);
> +
> +    return g_strdup(s->outdev);
> +}
> +
> +static void
> +filter_redirector_set_outdev(Object *obj, const char *value, Error **errp)
> +{
> +    RedirectorState *s = FILTER_REDIRECTOR(obj);
> +
> +    g_free(s->outdev);
> +    s->outdev = g_strdup(value);
> +}
> +
> +static void filter_redirector_init(Object *obj)
> +{
> +    object_property_add_str(obj, "indev", filter_redirector_get_indev,
> +                            filter_redirector_set_indev, NULL);
> +    object_property_add_str(obj, "outdev", filter_redirector_get_outdev,
> +                            filter_redirector_set_outdev, NULL);
> +}
> +
> +static void filter_redirector_fini(Object *obj)
> +{
> +    RedirectorState *s = FILTER_REDIRECTOR(obj);
> +
> +    g_free(s->indev);
> +    g_free(s->outdev);
> +}
> +
> +static const TypeInfo filter_redirector_info = {
> +    .name = TYPE_FILTER_REDIRECTOR,
> +    .parent = TYPE_NETFILTER,
> +    .class_init = filter_redirector_class_init,
> +    .instance_init = filter_redirector_init,
> +    .instance_finalize = filter_redirector_fini,
> +    .instance_size = sizeof(RedirectorState),
> +};
> +
> +static void register_types(void)
> +{
> +    type_register_static(&filter_redirector_info);
> +}
> +
> +type_init(register_types);
> diff --git a/qemu-options.hx b/qemu-options.hx
> index f31a240..1f796ed 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -3745,6 +3745,12 @@ queue @var{all|rx|tx} is an option that can be applied to any netfilter.
>  @option{tx}: the filter is attached to the transmit queue of the netdev,
>               where it will receive packets sent by the netdev.
>  
> +@item -object filter-redirector,id=@var{id},netdev=@var{netdevid},indev=@var{chardevid},outdev=@var{chardevid}[,queue=@var{all|rx|tx}]
> +
> +filter-redirector on netdev @var{netdevid},redirector can redirect filter's net packet to outdev.
> +and redirect indev's packet to filter.

Exceeds 80 characters limit. And need more work. e.g:

- Need to differs outdev id from indev id.
- Need to clarify at least one of outdev and indev needs to be set
- We're in fact redirect packet between chardev and netdev's queue (not
filter).

> +queue @var{all|rx|tx} is an option that can be applied to filter-redirector.

This line is unnecessary, we've already had

"
queue @var{all|rx|tx} is an option that can be applied to any netfilter.
"

> +
>  @item -object filter-dump,id=@var{id},netdev=@var{dev},file=@var{filename}][,maxlen=@var{len}]
>  
>  Dump the network traffic on netdev @var{dev} to the file specified by
> diff --git a/vl.c b/vl.c
> index f043009..4a9a9a0 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -2801,7 +2801,8 @@ static bool object_create_initial(const char *type)
>       * they depend on netdevs already existing
>       */
>      if (g_str_equal(type, "filter-buffer") ||
> -        g_str_equal(type, "filter-dump")) {
> +        g_str_equal(type, "filter-dump") ||
> +        g_str_equal(type, "filter-redirector")) {
>          return false;
>      }
>