[vbox-dev] [PATCH] demonstration patch for host-only networking packet direction

[Aleksey Ilyushin]

There is an unfortunate side effect in your patch -- the packets not intended for the host will be delivered to it even if a vboxnetX interface is not in the promiscuous mode.
 
On Sep 4, 2012, at 5:34 PM, Ed Maste wrote:

> On 30 August 2012 14:54, Ed Maste <emaste at freebsd.org> wrote:
>> ...
>> It appears that VirtualBox calls vboxNetFltPortOsXmit with fDst set to
>> INTNETTRUNKDIR_HOST if the MAC address matches that of the vboxnet
>> interface, or INTNETTRUNKDIR_WIRE otherwise.  To me this seems
>> undesirable in the case of a host-only network, where there really is
>> no 'wire' and all packets ought to be destined to/from the host.
>> 
>> I could implement something in the FreeBSD VBoxNetFlt and VBoxNetAdp
>> drivers for this, but it seems like it's a general issue.  Should
>> VirtualBox always set fDst to INTNETTRUNKDIR_HOST for host-only
>> interfaces?
> 
> Here's a quick hacky patch that demonstrates the change in behaviour.
> It does fix the issue I originally encountered.
> 
> 
> 
> diff --git a/src/VBox/HostDrivers/VBoxNetFlt/VBoxNetFltInternal.h
> b/src/VBox/HostDrivers/VBoxNetFlt/VBoxNetFltInternal.h
> index 90182a9..a01e060 100644
> --- a/src/VBox/HostDrivers/VBoxNetFlt/VBoxNetFltInternal.h
> +++ b/src/VBox/HostDrivers/VBoxNetFlt/VBoxNetFltInternal.h
> @@ -237,6 +237,8 @@ typedef struct VBOXNETFLTINS
>             struct task tskout;
>             /** The MAC address of the interface. */
>             RTMAC MacAddr;
> +            /** Host-only flag. */
> +            int host_only;
>             /** @} */
> # elif defined(RT_OS_WINDOWS)
>             /** @name Windows instance data.
> diff --git a/src/VBox/HostDrivers/VBoxNetFlt/freebsd/VBoxNetFlt-freebsd.c
> b/src/VBox/HostDrivers/VBoxNetFlt/freebsd/VBoxNetFlt-freebsd.c
> index 2912d76..b100bb4 100644
> --- a/src/VBox/HostDrivers/VBoxNetFlt/freebsd/VBoxNetFlt-freebsd.c
> +++ b/src/VBox/HostDrivers/VBoxNetFlt/freebsd/VBoxNetFlt-freebsd.c
> @@ -524,6 +524,14 @@ int vboxNetFltPortOsXmit(PVBOXNETFLTINS pThis,
> void *pvIfData, PINTNETSG pSG, ui
>     ifp = ASMAtomicUoReadPtrT(&pThis->u.s.ifp, struct ifnet *);
>     VBOXCURVNET_SET(ifp->if_vnet);
> 
> +    /* XXX Don't send to wire for host-only interface - see the thread at
> +     * https://www.virtualbox.org/pipermail/vbox-dev/2012-August/005316.html
> +     */
> +    if ((fDst & INTNETTRUNKDIR_WIRE) && pThis->u.s.host_only)
> +    {
> +        fDst = INTNETTRUNKDIR_HOST;
> +    }
> +
>     if (fDst & INTNETTRUNKDIR_WIRE)
>     {
>         m = vboxNetFltFreeBSDSGMBufFromSG(pThis, pSG);
> @@ -587,6 +595,7 @@ int vboxNetFltOsInitInstance(PVBOXNETFLTINS pThis,
> void *pvContext)
>     ifp = ifunit(pThis->szName);
>     if (ifp == NULL)
>         return VERR_INTNET_FLT_IF_NOT_FOUND;
> +    pThis->u.s.host_only = !strncmp(pThis->szName, "vboxnet", 7);
> 
>     /* Create a new netgraph node for this instance */
>     if (ng_make_node_common(&ng_vboxnetflt_typestruct, &node) != 0)
> 
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