netfilter: hook packets before net queue send

Capture packets that will be sent.

Signed-off-by: Yang Hongyang <yanghy@cn.fujitsu.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>

include/net/filter.h

@@ -58,4 +58,12 @@ struct NetFilterState {
     QTAILQ_ENTRY(NetFilterState) next;
 };
 
+ssize_t qemu_netfilter_receive(NetFilterState *nf,
+                               NetFilterDirection direction,
+                               NetClientState *sender,
+                               unsigned flags,
+                               const struct iovec *iov,
+                               int iovcnt,
+                               NetPacketSent *sent_cb);
+
 #endif /* QEMU_NET_FILTER_H */

net/filter.c

@@ -15,6 +15,23 @@
 #include "net/vhost_net.h"
 #include "qom/object_interfaces.h"
 
+ssize_t qemu_netfilter_receive(NetFilterState *nf,
+                               NetFilterDirection direction,
+                               NetClientState *sender,
+                               unsigned flags,
+                               const struct iovec *iov,
+                               int iovcnt,
+                               NetPacketSent *sent_cb)
+{
+    if (nf->direction == direction ||
+        nf->direction == NET_FILTER_DIRECTION_ALL) {
+        return NETFILTER_GET_CLASS(OBJECT(nf))->receive_iov(
+                                   nf, sender, flags, iov, iovcnt, sent_cb);
+    }
+
+    return 0;
+}
+
 static char *netfilter_get_netdev_id(Object *obj, Error **errp)
 {
     NetFilterState *nf = NETFILTER(obj);

net/net.c

@@ -561,6 +561,44 @@ int qemu_can_send_packet(NetClientState *sender)
     return 1;
 }
 
+static ssize_t filter_receive_iov(NetClientState *nc,
+                                  NetFilterDirection direction,
+                                  NetClientState *sender,
+                                  unsigned flags,
+                                  const struct iovec *iov,
+                                  int iovcnt,
+                                  NetPacketSent *sent_cb)
+{
+    ssize_t ret = 0;
+    NetFilterState *nf = NULL;
+
+    QTAILQ_FOREACH(nf, &nc->filters, next) {
+        ret = qemu_netfilter_receive(nf, direction, sender, flags, iov,
+                                     iovcnt, sent_cb);
+        if (ret) {
+            return ret;
+        }
+    }
+
+    return ret;
+}
+
+static ssize_t filter_receive(NetClientState *nc,
+                              NetFilterDirection direction,
+                              NetClientState *sender,
+                              unsigned flags,
+                              const uint8_t *data,
+                              size_t size,
+                              NetPacketSent *sent_cb)
+{
+    struct iovec iov = {
+        .iov_base = (void *)data,
+        .iov_len = size
+    };
+
+    return filter_receive_iov(nc, direction, sender, flags, &iov, 1, sent_cb);
+}
+
 ssize_t qemu_deliver_packet(NetClientState *sender,
                             unsigned flags,
                             const uint8_t *data,
@@ -632,6 +670,7 @@ static ssize_t qemu_send_packet_async_with_flags(NetClientState *sender,
                                                  NetPacketSent *sent_cb)
 {
     NetQueue *queue;
+    int ret;
 
 #ifdef DEBUG_NET
     printf("qemu_send_packet_async:\n");
@@ -642,6 +681,19 @@ static ssize_t qemu_send_packet_async_with_flags(NetClientState *sender,
         return size;
     }
 
+    /* Let filters handle the packet first */
+    ret = filter_receive(sender, NET_FILTER_DIRECTION_TX,
+                         sender, flags, buf, size, sent_cb);
+    if (ret) {
+        return ret;
+    }
+
+    ret = filter_receive(sender->peer, NET_FILTER_DIRECTION_RX,
+                         sender, flags, buf, size, sent_cb);
+    if (ret) {
+        return ret;
+    }
+
     queue = sender->peer->incoming_queue;
 
     return qemu_net_queue_send(queue, sender, flags, buf, size, sent_cb);
@@ -712,11 +764,25 @@ ssize_t qemu_sendv_packet_async(NetClientState *sender,
                                 NetPacketSent *sent_cb)
 {
     NetQueue *queue;
+    int ret;
 
     if (sender->link_down || !sender->peer) {
         return iov_size(iov, iovcnt);
     }
 
+    /* Let filters handle the packet first */
+    ret = filter_receive_iov(sender, NET_FILTER_DIRECTION_TX, sender,
+                             QEMU_NET_PACKET_FLAG_NONE, iov, iovcnt, sent_cb);
+    if (ret) {
+        return ret;
+    }
+
+    ret = filter_receive_iov(sender->peer, NET_FILTER_DIRECTION_RX, sender,
+                             QEMU_NET_PACKET_FLAG_NONE, iov, iovcnt, sent_cb);
+    if (ret) {
+        return ret;
+    }
+
     queue = sender->peer->incoming_queue;
 
     return qemu_net_queue_send_iov(queue, sender,