From a44ebeff6bbd6ef50db41b4195fca87b21aefd20 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Linus=20L=C3=BCssing?= <linus.luessing@c0d3.blue>
Date: Thu, 7 Jun 2018 00:46:24 +0200
Subject: [PATCH] batman-adv: Fix multicast TT issues with bogus ROAM flags
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Git-commit: a44ebeff6bbd6ef50db41b4195fca87b21aefd20
Patch-mainline: v4.18-rc6
References: bsc#1051510
When a (broken) node wrongly sends multicast TT entries with a ROAM
flag then this causes any receiving node to drop all entries for the
same multicast MAC address announced by other nodes, leading to
packet loss.
Fix this DoS vector by only storing TT sync flags. For multicast TT
non-sync'ing flag bits like ROAM are unused so far anyway.
Fixes: 1d8ab8d3c176 ("batman-adv: Modified forwarding behaviour for multicast packets")
Reported-by: Leonardo Mörlein <me@irrelefant.net>
Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
net/batman-adv/translation-table.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c
index 61ce300091f3..12a2b7d21376 100644
--- a/net/batman-adv/translation-table.c
+++ b/net/batman-adv/translation-table.c
@@ -1705,7 +1705,8 @@ static bool batadv_tt_global_add(struct batadv_priv *bat_priv,
ether_addr_copy(common->addr, tt_addr);
common->vid = vid;
- common->flags = flags & (~BATADV_TT_SYNC_MASK);
+ if (!is_multicast_ether_addr(common->addr))
+ common->flags = flags & (~BATADV_TT_SYNC_MASK);
tt_global_entry->roam_at = 0;
/* node must store current time in case of roaming. This is
@@ -1769,7 +1770,8 @@ static bool batadv_tt_global_add(struct batadv_priv *bat_priv,
* TT_CLIENT_TEMP, therefore they have to be copied in the
* client entry
*/
- common->flags |= flags & (~BATADV_TT_SYNC_MASK);
+ if (!is_multicast_ether_addr(common->addr))
+ common->flags |= flags & (~BATADV_TT_SYNC_MASK);
/* If there is the BATADV_TT_CLIENT_ROAM flag set, there is only
* one originator left in the list and we previously received a
--
2.18.0