[B.A.T.M.A.N.] [PATCHv2 4/7] batman-adv: drop unicast packets from other backbone gw

[B.A.T.M.A.N.] [PATCHv2 4/7] batman-adv: drop unicast packets from other backbone gw

[Andreas Pape]

Additional dropping of unicast packets received from another backbone gw of
the same backbone network before being forwarded to the same backbone again
is necessary. It was observed in a test setup that in rare cases these
frames lead to looping unicast traffic backbone->mesh->backbone.

Signed-off-by: Andreas Pape <apape@phoenixcontact.com>
---
 net/batman-adv/routing.c |   15 +++++++++++++++
 1 files changed, 15 insertions(+), 0 deletions(-)

diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c
index 4dd646a..606fd22 100644
--- a/net/batman-adv/routing.c
+++ b/net/batman-adv/routing.c
@@ -854,9 +854,11 @@ int batadv_recv_unicast_packet(struct sk_buff *skb,
 	int check, hdr_size = sizeof(*unicast_packet);
 	enum batadv_subtype subtype;
 	bool is4addr;
+	struct ethhdr *ethhdr;

 	unicast_packet = (struct batadv_unicast_packet *)skb->data;
 	unicast_4addr_packet = (struct batadv_unicast_4addr_packet *)skb->data;
+	ethhdr = eth_hdr(skb);

 	is4addr = unicast_packet->packet_type == BATADV_UNICAST_4ADDR;
 	/* the caller function should have already pulled 2 bytes */
@@ -896,6 +898,19 @@ int batadv_recv_unicast_packet(struct sk_buff *skb,
 			}
 		}

+		/* If this is a unicast packet from another backgone gw,
+		 * drop it.
+		 */
+		orig_addr = ethhdr->h_source;
+		orig_node = batadv_orig_hash_find(bat_priv, orig_addr);
+		if (batadv_bla_is_backbone_gw(skb, orig_node, hdr_size)) {
+			batadv_dbg(BATADV_DBG_BLA, bat_priv,
+				   "Dropped unicast pkt received from another backbone gw %pM.\n",
+				   orig_addr);
+
+			return NET_RX_DROP;
+		}
+
 		if (batadv_dat_snoop_incoming_arp_request(bat_priv, skb,
 							  hdr_size))
 			goto rx_success;
--
1.7.0.4



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Re: [B.A.T.M.A.N.] [PATCHv2 4/7] batman-adv: drop unicast packets from other backbone gw

[Sven Eckelmann]

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On Friday 26 February 2016 14:18:54 Andreas Pape wrote:
> @@ -896,6 +898,19 @@ int batadv_recv_unicast_packet(struct sk_buff *skb,
>  			}
>  		}
> 
> +		/* If this is a unicast packet from another backgone gw,
> +		 * drop it.
> +		 */
> +		orig_addr = ethhdr->h_source;
> +		orig_node = batadv_orig_hash_find(bat_priv, orig_addr);
> +		if (batadv_bla_is_backbone_gw(skb, orig_node, hdr_size)) {
> +			batadv_dbg(BATADV_DBG_BLA, bat_priv,
> +				   "Dropped unicast pkt received from another backbone gw %pM.\n",
> +				   orig_addr);
> +
> +			return NET_RX_DROP;
> +		}
> +

The orig_node was previously assigned via batadv_orig_hash_find. But this 
batadv_orig_hash_find already increased the reference pointer for orig_node. 
So we would now have an imbalance at the end of the function.

Kind regards,
	Sven

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Re: [B.A.T.M.A.N.] [PATCHv2 4/7] batman-adv: drop unicast packets from other backbone gw

[Simon Wunderlich]

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On Friday 26 February 2016 14:18:54 Andreas Pape wrote:
> Additional dropping of unicast packets received from another backbone gw of
> the same backbone network before being forwarded to the same backbone again
> is necessary. It was observed in a test setup that in rare cases these
> frames lead to looping unicast traffic backbone->mesh->backbone.

Yup, this is what we discussed!

Acked-by: Simon Wunderlich <sw@simonwunderlich.de>

Thanks!
     Simon

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