VLAN filtering with DSA

Hi,

Problem background:

Most DSA switch tags shift the EtherType to the right, causing the
master to not parse the VLAN as VLAN.
However, not all switches do that (example: tail tags), and if the DSA
master has "rx-vlan-filter: on" in ethtool -k, then we have a problem.
Therefore, I was thinking we could populate the VLAN table of the
master, just in case, so that it can work with a VLAN filtering master.
It would look something like this:

On 9/10/2020 8:07 AM, Vladimir Oltean wrote:
> Hi,
> 
> Problem background:
> 
> Most DSA switch tags shift the EtherType to the right, causing the
> master to not parse the VLAN as VLAN.
> However, not all switches do that (example: tail tags), and if the DSA
> master has "rx-vlan-filter: on" in ethtool -k, then we have a problem.
> Therefore, I was thinking we could populate the VLAN table of the
> master, just in case, so that it can work with a VLAN filtering master.
> It would look something like this:

Yes, doing what you suggest would make perfect sense for a DSA master 
that is capable of VLAN filtering, I did encounter that problem with 
e1000 and the dsa-loop.c mockup driver while working on a mock-up 802.1Q 
data path.

> 
> diff --git a/net/dsa/slave.c b/net/dsa/slave.c
> index 19b98a7231ec..b8aca2301c59 100644
> --- a/net/dsa/slave.c
> +++ b/net/dsa/slave.c
> @@ -307,9 +307,10 @@ static int dsa_slave_vlan_add(struct net_device *dev,
>   			      const struct switchdev_obj *obj,
>   			      struct switchdev_trans *trans)
>   {
> +	struct net_device *master = dsa_slave_to_master(dev);
>   	struct dsa_port *dp = dsa_slave_to_port(dev);
>   	struct switchdev_obj_port_vlan vlan;
> -	int err;
> +	int vid, err;
>   
>   	if (obj->orig_dev != dev)
>   		return -EOPNOTSUPP;
> @@ -336,6 +337,12 @@ static int dsa_slave_vlan_add(struct net_device *dev,
>   	if (err)
>   		return err;
>   
> +	for (vid = vlan.vid_begin; vid <= vlan.vid_end; vid++) {
> +		err = vlan_vid_add(master, htons(ETH_P_8021Q), vid);
> +		if (err)
> +			return err;
> +	}
> +
>   	return 0;
>   }
>   
> @@ -379,8 +386,10 @@ static int dsa_slave_port_obj_add(struct net_device *dev,
>   static int dsa_slave_vlan_del(struct net_device *dev,
>   			      const struct switchdev_obj *obj)
>   {
> +	struct net_device *master = dsa_slave_to_master(dev);
>   	struct dsa_port *dp = dsa_slave_to_port(dev);
>   	struct switchdev_obj_port_vlan *vlan;
> +	int vid, err;
>   
>   	if (obj->orig_dev != dev)
>   		return -EOPNOTSUPP;
> @@ -396,7 +405,14 @@ static int dsa_slave_vlan_del(struct net_device *dev,
>   	/* Do not deprogram the CPU port as it may be shared with other user
>   	 * ports which can be members of this VLAN as well.
>   	 */
> -	return dsa_port_vlan_del(dp, vlan);
> +	err = dsa_port_vlan_del(dp, vlan);
> +	if (err)
> +		return err;
> +
> +	for (vid = vlan->vid_begin; vid <= vlan->vid_end; vid++)
> +		vlan_vid_del(master, htons(ETH_P_8021Q), vid);
> +
> +	return 0;
>   }
>   
>   static int dsa_slave_port_obj_del(struct net_device *dev,
> @@ -1241,6 +1257,7 @@ static int dsa_slave_get_ts_info(struct net_device *dev,
>   static int dsa_slave_vlan_rx_add_vid(struct net_device *dev, __be16 proto,
>   				     u16 vid)
>   {
> +	struct net_device *master = dsa_slave_to_master(dev);
>   	struct dsa_port *dp = dsa_slave_to_port(dev);
>   	struct switchdev_obj_port_vlan vlan = {
>   		.obj.id = SWITCHDEV_OBJ_ID_PORT_VLAN,
> @@ -1294,12 +1311,13 @@ static int dsa_slave_vlan_rx_add_vid(struct net_device *dev, __be16 proto,
>   	if (ret)
>   		return ret;
>   
> -	return 0;
> +	return vlan_vid_add(master, proto, vid);
>   }
>   
>   static int dsa_slave_vlan_rx_kill_vid(struct net_device *dev, __be16 proto,
>   				      u16 vid)
>   {
> +	struct net_device *master = dsa_slave_to_master(dev);
>   	struct dsa_port *dp = dsa_slave_to_port(dev);
>   	struct switchdev_obj_port_vlan vlan = {
>   		.vid_begin = vid,
> @@ -1332,7 +1350,13 @@ static int dsa_slave_vlan_rx_kill_vid(struct net_device *dev, __be16 proto,
>   	/* Do not deprogram the CPU port as it may be shared with other user
>   	 * ports which can be members of this VLAN as well.
>   	 */
> -	return dsa_port_vlan_del(dp, &vlan);
> +	ret = dsa_port_vlan_del(dp, &vlan);
> +	if (ret)
> +		return ret;
> +
> +	vlan_vid_del(master, proto, vid);
> +
> +	return 0;
>   }
>   
>   struct dsa_hw_port {
>

On Thu, Sep 10, 2020 at 11:42:02AM -0700, Florian Fainelli wrote:
> On 9/10/2020 8:07 AM, Vladimir Oltean wrote:
> Yes, doing what you suggest would make perfect sense for a DSA master that
> is capable of VLAN filtering, I did encounter that problem with e1000 and
> the dsa-loop.c mockup driver while working on a mock-up 802.1Q data path.

Yes, I have another patch where I add those VLANs from tag_8021q.c which
I did not show here.

But if the DSA switch that uses tag_8021q is cascaded to another one,
that's of little use if the upper switch does not propagate that
configuration to its own upstream.

Thanks,
-Vladimir

On 9/10/2020 12:01 PM, Vladimir Oltean wrote:
> On Thu, Sep 10, 2020 at 11:42:02AM -0700, Florian Fainelli wrote:
>> On 9/10/2020 8:07 AM, Vladimir Oltean wrote:
>> Yes, doing what you suggest would make perfect sense for a DSA master that
>> is capable of VLAN filtering, I did encounter that problem with e1000 and
>> the dsa-loop.c mockup driver while working on a mock-up 802.1Q data path.
> 
> Yes, I have another patch where I add those VLANs from tag_8021q.c which
> I did not show here.
> 
> But if the DSA switch that uses tag_8021q is cascaded to another one,
> that's of little use if the upper switch does not propagate that
> configuration to its own upstream.

Yes, that would not work. As soon as you have a bridge spanning any of 
those switches, does not the problem go away by virtue of the switch 
port forcing the DSA master/upstream to be in promiscuous mode?

On Fri, Sep 11, 2020 at 07:30:42PM +0300, Vladimir Oltean wrote:
> Currently there are other places in the network stack that don't really
> work with a network interface that has problems with an interface that
> has "rx-vlan-filter: on" in ethtool -k.

Wow, I should learn how to write.
I meant:

Currently there are other places in the network stack that don't really
work with a network interface that has "rx-vlan-filter: on" in
ethtool -k.