diff options
| author | Linus Lüssing <linus.luessing@c0d3.blue> | 2018-03-22 00:21:32 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-05-30 07:50:38 +0200 |
| commit | 511d9451a37607246483bff6741cad2ea7e3924b (patch) | |
| tree | ea7d8b66094c5e8581036da67314b9d21ec037fb /net | |
| parent | 00a7d83c8acb9843f27ebf06208cd7f3059667e5 (diff) | |
batman-adv: fix packet loss for broadcasted DHCP packets to a server
[ Upstream commit a752c0a4524889cdc0765925258fd1fd72344100 ]
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: be7af5cf9cae ("batman-adv: refactoring gateway handling code")
Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net')
| -rw-r--r-- | net/batman-adv/gateway_client.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/net/batman-adv/gateway_client.c b/net/batman-adv/gateway_client.c index de055d64debe..ed9aaf30fbcf 100644 --- a/net/batman-adv/gateway_client.c +++ b/net/batman-adv/gateway_client.c @@ -715,6 +715,9 @@ 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) |