B.A.T.M.A.N. V aggregation causes originator loops
It was reported that some installations with enabled OGMv2 aggregation can cause the own originator to appear in the originator table via a different node:
My originator messages look wrong as I can see my host originator messages along with all the neigbor nodes: root@OpenWrt:/etc/config# batctl o -n [B.A.T.M.A.N. adv 2020.1-openwrt-2, MainIF/MAC: mesh0/00:30:1a:4e:b8:26 (bat0/f2:07:f1:5f:e0:78 BATMAN_V)] Originator last-seen ( throughput) Nexthop [outgoingIF] * 00:30:1a:4e:b8:18 0.570s ( 86.7) 00:30:1a:4e:b8:2e [ mesh0] 00:30:1a:4e:b8:18 0.570s ( 21.6) 00:30:1a:4e:b8:18 [ mesh0] * 00:30:1a:4e:b8:2e 1.510s ( 212.6) 00:30:1a:4e:b8:2e [ mesh0] 00:30:1a:4e:b8:2e 1.510s ( 38.9) 00:30:1a:4e:b8:18 [ mesh0] 00:30:1a:4e:b8:26 1.510s ( 38.9) 00:30:1a:4e:b8:18 [ mesh0] * 00:30:1a:4e:b8:26 1.510s ( 108.9) 00:30:1a:4e:b8:2e [ mesh0] root@OpenWrt:/etc/config# batctl n -n [B.A.T.M.A.N. adv 2020.1-openwrt-2, MainIF/MAC: mesh0/00:30:1a:4e:b8:26 (bat0/f2:07:f1:5f:e0:78 BATMAN_V)] IF Neighbor last-seen 00:30:1a:4e:b8:2e 0.490s ( 179.0) [ mesh0] 00:30:1a:4e:b8:18 0.380s ( 79.2) [ mesh0]
Disabling aggregation seems to solve this problem.
Updated by Sven Eckelmann 3 months ago
There was also following in the IRC channel:
[2020-06-17 12:29:46] <nLi> marec: Yes, I revied the code and found that aggreated OGM does not honor the Preliminary Check for OGMv2. -Own Message Check: If the originator address of the OGM is our own the message must be silently dropped as this OGM originated from this node. [2020-06-17 12:45:54] <nLi> marec: For now i disabled aggregated OGM for my deployment, which resulted in the expected behaviour. I.E the node is no longer listing itself in the orginiator table. [2020-06-17 12:55:31] <nLi> marec: I suppose that the the "Own Message Check" needs to be implemented in either the while loop in batadv_v_ogm_packet_recv or batadv_v_ogm_process for each OGM that was aggregated, any thoughts on your side?
Updated by Sven Eckelmann 3 months ago
- Status changed from New to In Progress
- Description updated (diff)
This is the proof of concept patch from Linus: https://git.open-mesh.org/batman-adv.git/commit/0115502eab54a80f2c05884efce6ee164ed3cd9f
batman-adv: Fix own OGM check in aggregated OGMs The own OGM check is currently misplaced and can lead to the following issues: For one thing we might receive an aggregated OGM from a neighbor node which has our own OGM in the first place. We would then not only skip our own OGM but erroneously also any other, following OGM in the aggregate. For another, we might receive an OGM aggregate which has our own OGM in a place other then the first one. Then we would wrongly not skip this OGM, leading to populating the orginator and gateway table with ourself. Fixes: 667996ebeab ("batman-adv: OGMv2 - implement originators logic") Signed-off-by: Linus LÃ¼ssing <email@example.com> --- net/batman-adv/bat_v_ogm.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/net/batman-adv/bat_v_ogm.c b/net/batman-adv/bat_v_ogm.c index 0f8495b9..731810ee 100644 --- a/net/batman-adv/bat_v_ogm.c +++ b/net/batman-adv/bat_v_ogm.c @@ -881,6 +881,12 @@ static void batadv_v_ogm_process(const struct sk_buff *skb, int ogm_offset, ntohl(ogm_packet->seqno), ogm_throughput, ogm_packet->ttl, ogm_packet->version, ntohs(ogm_packet->tvlv_len)); + if (batadv_is_my_mac(bat_priv, ogm_packet->orig)) + batadv_dbg(BATADV_DBG_BATMAN, bat_priv, + "Drop packet: originator packet from ourself\n"); + return; + } + /* If the throughput metric is 0, immediately drop the packet. No need * to create orig_node / neigh_node for an unusable route. */ @@ -1008,11 +1014,6 @@ int batadv_v_ogm_packet_recv(struct sk_buff *skb, if (batadv_is_my_mac(bat_priv, ethhdr->h_source)) goto free_skb; - ogm_packet = (struct batadv_ogm2_packet *)skb->data; - - if (batadv_is_my_mac(bat_priv, ogm_packet->orig)) - goto free_skb; - batadv_inc_counter(bat_priv, BATADV_CNT_MGMT_RX); batadv_add_counter(bat_priv, BATADV_CNT_MGMT_RX_BYTES, skb->len + ETH_HLEN);