linux/net/batman-adv
Linus Lüssing a752c0a452 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: be7af5cf9c ("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>
2018-03-24 10:25:49 +01:00
..
bat_algo.c batman-adv: Add kernel-doc to externally visible functions 2017-12-15 17:29:24 +01:00
bat_algo.h batman-adv: Add SPDX license identifier above copyright header 2017-12-15 17:22:45 +01:00
bat_iv_ogm.c batman-adv: Fix internal interface indices types 2018-02-25 20:19:34 +01:00
bat_iv_ogm.h batman-adv: Add SPDX license identifier above copyright header 2017-12-15 17:22:45 +01:00
bat_v_elp.c batman-adv: Convert packet.h to uapi header 2017-12-21 15:35:53 -05:00
bat_v_elp.h batman-adv: Add SPDX license identifier above copyright header 2017-12-15 17:22:45 +01:00
bat_v_ogm.c batman-adv: Convert packet.h to uapi header 2017-12-21 15:35:53 -05:00
bat_v_ogm.h batman-adv: Add SPDX license identifier above copyright header 2017-12-15 17:22:45 +01:00
bat_v.c batman-adv: Ignore invalid batadv_v_gw during netlink send 2018-02-25 20:11:11 +01:00
bat_v.h batman-adv: Add SPDX license identifier above copyright header 2017-12-15 17:22:45 +01:00
bitarray.c batman-adv: Use parentheses in function kernel-doc 2017-12-15 17:29:20 +01:00
bitarray.h batman-adv: Add kernel-doc to functions in headers 2017-12-15 17:29:23 +01:00
bridge_loop_avoidance.c batman-adv: Fix netlink dumping of BLA backbones 2018-02-25 20:11:59 +01:00
bridge_loop_avoidance.h batman-adv: Use parentheses in function kernel-doc 2017-12-15 17:29:20 +01:00
debugfs.c batman-adv: Add kernel-doc to externally visible functions 2017-12-15 17:29:24 +01:00
debugfs.h batman-adv: Add SPDX license identifier above copyright header 2017-12-15 17:22:45 +01:00
distributed-arp-table.c batman-adv: fix header size check in batadv_dbg_arp() 2018-03-16 20:23:48 +01:00
distributed-arp-table.h batman-adv: Convert packet.h to uapi header 2017-12-21 15:35:53 -05:00
fragmentation.c batman-adv: invalidate checksum on fragment reassembly 2018-02-25 20:00:44 +01:00
fragmentation.h batman-adv: Use parentheses in function kernel-doc 2017-12-15 17:29:20 +01:00
gateway_client.c batman-adv: fix packet loss for broadcasted DHCP packets to a server 2018-03-24 10:25:49 +01:00
gateway_client.h batman-adv: Add SPDX license identifier above copyright header 2017-12-15 17:22:45 +01:00
gateway_common.c batman-adv: Convert packet.h to uapi header 2017-12-21 15:35:53 -05:00
gateway_common.h batman-adv: Use inline kernel-doc for enum/struct 2017-12-15 17:29:20 +01:00
hard-interface.c batman-adv: Fix internal interface indices types 2018-02-25 20:19:34 +01:00
hard-interface.h batman-adv: Add kernel-doc to functions in headers 2017-12-15 17:29:23 +01:00
hash.c batman-adv: Add kernel-doc to externally visible functions 2017-12-15 17:29:24 +01:00
hash.h batman-adv: Add kernel-doc to functions in headers 2017-12-15 17:29:23 +01:00
icmp_socket.c batman-adv: Add missing include for EPOLL* constants 2018-03-18 09:58:23 +01:00
icmp_socket.h batman-adv: Add SPDX license identifier above copyright header 2017-12-15 17:22:45 +01:00
Kconfig batman-adv: Add license header to Kconfig 2017-12-15 17:24:08 +01:00
log.c batman-adv: Add missing include for EPOLL* constants 2018-03-18 09:58:23 +01:00
log.h batman-adv: Add kernel-doc to functions in headers 2017-12-15 17:29:23 +01:00
main.c batman-adv: Convert packet.h to uapi header 2017-12-21 15:35:53 -05:00
main.h batman-adv: Convert packet.h to uapi header 2017-12-21 15:35:53 -05:00
Makefile batman-adv: Add SPDX license identifier above copyright header 2017-12-15 17:22:45 +01:00
multicast.c batman-adv: fix multicast-via-unicast transmission with AP isolation 2018-03-24 10:25:07 +01:00
multicast.h batman-adv: Use inline kernel-doc for enum/struct 2017-12-15 17:29:20 +01:00
netlink.c batman-adv: Convert packet.h to uapi header 2017-12-21 15:35:53 -05:00
netlink.h batman-adv: Add SPDX license identifier above copyright header 2017-12-15 17:22:45 +01:00
network-coding.c batman-adv: Convert packet.h to uapi header 2017-12-21 15:35:53 -05:00
network-coding.h batman-adv: Add SPDX license identifier above copyright header 2017-12-15 17:22:45 +01:00
originator.c batman-adv: Fix internal interface indices types 2018-02-25 20:19:34 +01:00
originator.h batman-adv: Fix internal interface indices types 2018-02-25 20:19:34 +01:00
routing.c batman-adv: Fix skbuff rcsum on packet reroute 2018-03-18 13:20:32 +01:00
routing.h batman-adv: Add SPDX license identifier above copyright header 2017-12-15 17:22:45 +01:00
send.c batman-adv: Add kernel-doc to externally visible functions 2017-12-15 17:29:24 +01:00
send.h batman-adv: Convert packet.h to uapi header 2017-12-21 15:35:53 -05:00
soft-interface.c batman-adv: fix packet checksum in receive path 2018-02-25 20:00:44 +01:00
soft-interface.h batman-adv: Add SPDX license identifier above copyright header 2017-12-15 17:22:45 +01:00
sysfs.c batman-adv: Convert packet.h to uapi header 2017-12-21 15:35:53 -05:00
sysfs.h batman-adv: Add kernel-doc to structs in headers 2017-12-15 17:29:22 +01:00
tp_meter.c batman-adv: Convert packet.h to uapi header 2017-12-21 15:35:53 -05:00
tp_meter.h batman-adv: Add SPDX license identifier above copyright header 2017-12-15 17:22:45 +01:00
translation-table.c batman-adv: Convert packet.h to uapi header 2017-12-21 15:35:53 -05:00
translation-table.h batman-adv: Add SPDX license identifier above copyright header 2017-12-15 17:22:45 +01:00
tvlv.c batman-adv: Convert packet.h to uapi header 2017-12-21 15:35:53 -05:00
tvlv.h batman-adv: Add SPDX license identifier above copyright header 2017-12-15 17:22:45 +01:00
types.h batman-adv: Fix internal interface indices types 2018-02-25 20:19:34 +01:00