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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , b.a.t.m.a.n@lists.open-mesh.org, Sven Eckelmann , stable@vger.kernel.org, Simon Wunderlich Subject: [PATCH net v2 08/14] batman-adv: tt: only transmit local ROAM flag together with DEL Date: Fri, 30 Oct 2026 14:50:59 +0100 Message-ID: <20261030135105.2555887-9-sw@simonwunderlich.de> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20261030135105.2555887-1-sw@simonwunderlich.de> References: <20261030135105.2555887-1-sw@simonwunderlich.de> X-Mailing-List: netdev@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Sven Eckelmann BATADV_TT_CLIENT_ROAM is part of BATADV_TT_REMOTE_MASK but on the wire it only has a defined meaning together with BATADV_TT_CLIENT_DEL: the originator no longer serves the client because it roamed to another node. Such a DEL is only relevant for events (non-full table requests). An ADD carrying ROAM is processed (by accident) by the receiver like a ROAMING_ADV: a newly created global entry is marked as roaming and is excluded from the global CRC. But the sender includes it in its local CRC. But such a behavior doesn't make sense for non-ROAM_ADV because a new TTVN is meant as announced commit of the local TT table of a node and should therefore not be used to create a temporary (roam) global entry in a node. At the moment, such an ADD with the BATADV_TT_CLIENT_ROAM flag set can happen due to two mechanisms: batadv_tt_local_valid() copies all flags of the local entry into a full table response. It is not synchronized with batadv_tt_local_mark_removed(). An entry which was marked as ROAM|PENDING by a ROAMING_ADV is still part of the current TTVN and is sent with the ROAM flag set. The receivers then create a roaming global entry for it and detect a CRC mismatch, which causes them to request the full table again. The same can happen for an ADD change which is queued for an entry which (still) has the ROAM flag set. For example when only the dynamic WIFI or ISOLA flags were updated. It is not triggered by batadv_send_other_tt_response() because batadv_tt_global_valid() is already taking care of filtering out BATADV_TT_CLIENT_ROAM entries. For the two problematic announcement mechanism, only send the ROAM flag of local entries together with a DEL. This only fixes the ROAM marking of the global entry and the resulting CRC mismatch. When the requester of the full table is the node which sent the ROAMING_ADV, the still announced entry will (independent of the ROAM flag) cause batadv_tt_global_purge_local() to remove the requester's own (new) local entry for the client. This is not addressed here. Cc: stable@vger.kernel.org Fixes: 27b37ebfa2d2 ("batman-adv: correctly pass the client flag on tt_response") Fixes: 068ee6e204e1 ("batman-adv: roaming handling mechanism redesign") Signed-off-by: Sven Eckelmann Signed-off-by: Simon Wunderlich --- net/batman-adv/translation-table.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) diff --git a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c index 3349376a9087d..39b61426f1680 100644 --- a/net/batman-adv/translation-table.c +++ b/net/batman-adv/translation-table.c @@ -643,9 +643,17 @@ static void __batadv_tt_local_event(struct batadv_priv *bat_priv, ether_addr_copy(tt_change_node->change.addr, common->addr); tt_change_node->change.vid = htons(common->vid); - tt_change_node->change.flags = flags; del_op_requested = flags & BATADV_TT_CLIENT_DEL; + /* the ROAM flag is only meaningful for the receiver in combination + * with a DEL. An ADD with ROAM would be interpreted as a roaming + * advertisement + */ + if (!del_op_requested) + flags &= ~BATADV_TT_CLIENT_ROAM; + + tt_change_node->change.flags = flags; + /* check for ADD+DEL, DEL+ADD, ADD+ADD or DEL+DEL events */ spin_lock_bh(&bat_priv->tt.changes_list_lock); changes = READ_ONCE(bat_priv->tt.local_changes); @@ -3342,8 +3350,12 @@ static bool batadv_tt_local_valid(void *entry_ptr, if (tt_flags & BATADV_TT_CLIENT_NEW) return false; + /* the entry is (still) announced. A ROAM flag of an entry which is + * pending to be removed must not be transmitted. Otherwise, the + * receiver would handle it like a roaming advertisement + */ if (flags) - *flags = tt_flags; + *flags = tt_flags & ~BATADV_TT_CLIENT_ROAM; return true; } -- 2.47.3