Subject: Re: [PATCH net-next 3/4] bridge: Consider the Nearest Customer Bridge group addresses

From: Stephen Hemminger <[email-masked]>
Date: Mon, 9 Jun 2014 08:52:43 -0700

On Mon,  9 Jun 2014 20:34:46 +0900
Toshiaki Makita <[email-masked]> wrote:

> An 802.1ad bridge must forward the Nearest Customer Bridge group addresses.
>  01-80-C2-00-00-00
>  01-80-C2-00-00-0B
>  01-80-C2-00-00-0C
>  01-80-C2-00-00-0D
>  01-80-C2-00-00-0F
> (For details, see IEEE 802.1Q-2011 8.6.3.)
> 
> An exception is the br->group_addr, which needs to be passed to the higher
> layer entity so that STP works.
> 
> Signed-off-by: Toshiaki Makita <[email-masked]>
> ---
>  net/bridge/br_input.c   | 15 ++++++++++++++-
>  net/bridge/br_private.h | 10 ++++++++++
>  2 files changed, 24 insertions(+), 1 deletion(-)
> 
> diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
> index 04d6348..b05d419 100644
> --- a/net/bridge/br_input.c
> +++ b/net/bridge/br_input.c
> @@ -194,13 +194,26 @@ rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
>  		case 0x00:	/* Bridge Group Address */
>  			/* If STP is turned off,
>  			   then must forward to keep loop detection */
> -			if (p->br->stp_enabled == BR_NO_STP)
> +			if (p->br->stp_enabled == BR_NO_STP ||
> +			    (br_vlan_enabled(p->br) &&
> +			     br_vlan_get_proto(p->br) == htons(ETH_P_8021AD) &&
> +			     p->br->group_addr[5] != dest[5]))
>  				goto forward;
>  			break;
>  
>  		case 0x01:	/* IEEE MAC (Pause) */
>  			goto drop;
>  
> +		case 0x0B:
> +		case 0x0C:
> +		case 0x0D:
> +		case 0x0F:
> +			/* The Nearest Customer Bridge group address */
> +			if (br_vlan_enabled(p->br) &&
> +			    br_vlan_get_proto(p->br) == htons(ETH_P_8021AD) &&
> +			    p->br->group_addr[5] != dest[5])
> +				goto forward;
> +			/* fall through */
>  		default:
>  			/* Allow selective forwarding for most other protocols */
>  			if (p->br->group_fwd_mask & (1u << dest[5]))
> diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
> index b65fee9..65204c2 100644
> --- a/net/bridge/br_private.h
> +++ b/net/bridge/br_private.h
> @@ -647,6 +647,11 @@ static inline int br_vlan_enabled(struct net_bridge *br)
>  {
>  	return br->vlan_enabled;
>  }
> +
> +static inline __be16 br_vlan_get_proto(struct net_bridge *br)
> +{
> +	return br->vlan_proto;
> +}
>  #else
>  static inline bool br_allowed_ingress(struct net_bridge *br,
>  				      struct net_port_vlans *v,
> @@ -742,6 +747,11 @@ static inline int br_vlan_enabled(struct net_bridge *br)
>  {
>  	return 0;
>  }
> +
> +static inline __be16 br_vlan_get_proto(struct net_bridge *br)
> +{
> +	return 0;
> +}
>  #endif
>  
>  /* br_netfilter.c */

Rather than special casing this around vlan filtering, I would prefer
the code always forward these packets, or manipulate group_fwd_mask
to allow it that way.