79 lines
3.2 KiB
Diff
79 lines
3.2 KiB
Diff
From: Linus Lüssing <linus.luessing@c0d3.blue>
|
|
Date: Thu, 22 Mar 2018 00:21:32 +0100
|
|
Subject: batman-adv: fix packet loss for broadcasted DHCP packets to a server
|
|
|
|
DHCP connectivity issues can currently occur if the following conditions
|
|
are met:
|
|
|
|
1) A DHCP packet from a client to a server
|
|
2) This packet has a multicast destination
|
|
3) This destination has a matching entry in the translation table
|
|
(FF:FF:FF:FF:FF:FF for IPv4, 33:33:00:01:00:02/33:33:00:01:00:03
|
|
for IPv6)
|
|
4) The orig-node determined by TT for the multicast destination
|
|
does not match the orig-node determined by best-gateway-selection
|
|
|
|
In this case the DHCP packet will be dropped.
|
|
|
|
The "gateway-out-of-range" check is supposed to only be applied to
|
|
unicasted DHCP packets to a specific DHCP server.
|
|
|
|
In that case dropping the the unicasted frame forces the client to
|
|
retry via a broadcasted one, but now directed to the new best
|
|
gateway.
|
|
|
|
A DHCP packet with broadcast/multicast destination is already ensured to
|
|
always be delivered to the best gateway. Dropping a multicasted
|
|
DHCP packet here will only prevent completing DHCP as there is no
|
|
other fallback.
|
|
|
|
So far, it seems the unicast check was implicitly performed by
|
|
expecting the batadv_transtable_search() to return NULL for multicast
|
|
destinations. However, a multicast address could have always ended up in
|
|
the translation table and in fact is now common.
|
|
|
|
To fix this potential loss of a DHCP client-to-server packet to a
|
|
multicast address this patch adds an explicit multicast destination
|
|
check to reliably bail out of the gateway-out-of-range check for such
|
|
destinations.
|
|
|
|
The issue and fix were tested in the following three node setup:
|
|
|
|
- Line topology, A-B-C
|
|
- A: gateway client, DHCP client
|
|
- B: gateway server, hop-penalty increased: 30->60, DHCP server
|
|
- C: gateway server, code modifications to announce FF:FF:FF:FF:FF:FF
|
|
|
|
Without this patch, A would never transmit its DHCP Discover packet
|
|
due to an always "out-of-range" condition. With this patch,
|
|
a full DHCP handshake between A and B was possible again.
|
|
|
|
Fixes: afae4e42aae6 ("batman-adv: refactoring gateway handling code")
|
|
Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
|
|
Signed-off-by: Sven Eckelmann <sven@narfation.org>
|
|
|
|
Origin: upstream, https://git.open-mesh.org/batman-adv.git/commit/49b2132f0fe2753a3b46103db9719898c5cd44aa
|
|
|
|
diff --git a/net/batman-adv/gateway_client.c b/net/batman-adv/gateway_client.c
|
|
index 52b8bd6ec43183519a63483950c2e886e47a6f9e..f1fdf4e7f5c3ce7f20339dcee3b6e43290ea3b4e 100644
|
|
--- a/net/batman-adv/gateway_client.c
|
|
+++ b/net/batman-adv/gateway_client.c
|
|
@@ -705,7 +705,7 @@ bool batadv_gw_out_of_range(struct batadv_priv *bat_priv,
|
|
{
|
|
struct batadv_neigh_node *neigh_curr = NULL;
|
|
struct batadv_neigh_node *neigh_old = NULL;
|
|
- struct batadv_orig_node *orig_dst_node;
|
|
+ struct batadv_orig_node *orig_dst_node = NULL;
|
|
struct batadv_gw_node *gw_node = NULL;
|
|
struct batadv_gw_node *curr_gw = NULL;
|
|
struct batadv_neigh_ifinfo *curr_ifinfo, *old_ifinfo;
|
|
@@ -716,6 +716,9 @@ bool batadv_gw_out_of_range(struct batadv_priv *bat_priv,
|
|
|
|
vid = batadv_get_vid(skb, 0);
|
|
|
|
+ if (is_multicast_ether_addr(ethhdr->h_dest))
|
|
+ goto out;
|
|
+
|
|
orig_dst_node = batadv_transtable_search(bat_priv, ethhdr->h_source,
|
|
ethhdr->h_dest, vid);
|
|
if (!orig_dst_node)
|