From: Linus Lüssing Date: Wed, 6 Jun 2018 22:46:24 +0000 (+0200) Subject: batman-adv: Fix multicast TT issues with bogus ROAM flags X-Git-Tag: v4.18-rc6~28^2~8^2 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a44ebeff6bbd6ef50db41b4195fca87b21aefd20;p=thirdparty%2Flinux.git batman-adv: Fix multicast TT issues with bogus ROAM flags 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 Signed-off-by: Linus Lüssing Signed-off-by: Simon Wunderlich --- diff --git a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c index 61ce300091f32..12a2b7d213767 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