[PATCH v2] batman-adv: Introduce no noflood mark

Linus Lüssing
2019-05-07T07:28:21Z

This mark prevents a multicast packet being flooded through the whole
mesh. The advantage of marking certain multicast packets via e.g.
ebtables instead of dropping is then the following:

This allows an administrator to let specific multicast packets pass as
long as they are forwarded to a limited number of nodes only and are
therefore creating no burdon to unrelated nodes.

Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>

---

https://www.open-mesh.org/projects/batman-adv/wiki/Noflood-broadcast-prevention

Changelog v2:

* rebased to master
* sysfs -> netlink
---
include/uapi/linux/batman_adv.h | 12 ++++++++++++
net/batman-adv/netlink.c | 22 ++++++++++++++++++++++
net/batman-adv/soft-interface.c | 20 ++++++++++++++++++++
net/batman-adv/types.h | 12 ++++++++++++
4 files changed, 66 insertions(+)

diff --git a/include/uapi/linux/batman_adv.h b/include/uapi/linux/batman_adv.h
index 67f46367..6fabb7aa 100644
--- a/include/uapi/linux/batman_adv.h
+++ b/include/uapi/linux/batman_adv.h
@@ -480,6 +480,18 @@ enum batadv_nl_attrs {
*/
BATADV_ATTR_MULTICAST_FANOUT,

+ /**
+ * @BATADV_ATTR_NOFLOOD_MARK: the noflood mark which allows to tag
+ * frames which should never be broadcast flooded through the mesh.
+ */
+ BATADV_ATTR_NOFLOOD_MARK,
+
+ /**
+ * @BATADV_ATTR_NOFLOOD_MASK: the noflood (bit)mask which allows to tag
+ * frames which should never be broadcast flooded through the mesh.
+ */
+ BATADV_ATTR_NOFLOOD_MASK,
+
/* add attributes above here, update the policy in netlink.c */

/**
diff --git a/net/batman-adv/netlink.c b/net/batman-adv/netlink.c
index a67720fa..a08a67af 100644
--- a/net/batman-adv/netlink.c
+++ b/net/batman-adv/netlink.c
@@ -134,6 +134,8 @@ static const struct nla_policy batadv_netlink_policy[NUM_BATADV_ATTR] = {
[BATADV_ATTR_AP_ISOLATION_ENABLED] = { .type = NLA_U8 },
[BATADV_ATTR_ISOLATION_MARK] = { .type = NLA_U32 },
[BATADV_ATTR_ISOLATION_MASK] = { .type = NLA_U32 },
+ [BATADV_ATTR_NOFLOOD_MARK] = { .type = NLA_U32 },
+ [BATADV_ATTR_NOFLOOD_MASK] = { .type = NLA_U32 },
[BATADV_ATTR_BONDING_ENABLED] = { .type = NLA_U8 },
[BATADV_ATTR_BRIDGE_LOOP_AVOIDANCE_ENABLED] = { .type = NLA_U8 },
[BATADV_ATTR_DISTRIBUTED_ARP_TABLE_ENABLED] = { .type = NLA_U8 },
@@ -286,6 +288,14 @@ static int batadv_netlink_mesh_fill(struct sk_buff *msg,
bat_priv->isolation_mark_mask))
goto nla_put_failure;

+ if (nla_put_u32(msg, BATADV_ATTR_NOFLOOD_MARK,
+ bat_priv->noflood_mark))
+ goto nla_put_failure;
+
+ if (nla_put_u32(msg, BATADV_ATTR_NOFLOOD_MASK,
+ bat_priv->noflood_mark_mask))
+ goto nla_put_failure;
+
if (nla_put_u8(msg, BATADV_ATTR_BONDING_ENABLED,
!!atomic_read(&bat_priv->bonding)))
goto nla_put_failure;
@@ -466,6 +476,18 @@ static int batadv_netlink_set_mesh(struct sk_buff *skb, struct genl_info *info)
bat_priv->isolation_mark_mask = nla_get_u32(attr);
}

+ if (info->attrs[BATADV_ATTR_NOFLOOD_MARK]) {
+ attr = info->attrs[BATADV_ATTR_NOFLOOD_MARK];
+
+ bat_priv->noflood_mark = nla_get_u32(attr);
+ }
+
+ if (info->attrs[BATADV_ATTR_NOFLOOD_MASK]) {
+ attr = info->attrs[BATADV_ATTR_NOFLOOD_MASK];
+
+ bat_priv->noflood_mark_mask = nla_get_u32(attr);
+ }
+
if (info->attrs[BATADV_ATTR_BONDING_ENABLED]) {
attr = info->attrs[BATADV_ATTR_BONDING_ENABLED];

diff --git a/net/batman-adv/soft-interface.c b/net/batman-adv/soft-interface.c
index a7677e1d..6912f651 100644
--- a/net/batman-adv/soft-interface.c
+++ b/net/batman-adv/soft-interface.c
@@ -176,6 +176,23 @@ static void batadv_interface_set_rx_mode(struct net_device *dev)
{
}

+/**
+ * batadv_send_skb_has_noflood_mark() - check if packet has a noflood mark
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: the packet to check
+ *
+ * Return: True if the skb's mark matches a configured noflood mark and
+ * noflood mark mask. False otherwise.
+ */
+static bool
+batadv_skb_has_noflood_mark(struct batadv_priv *bat_priv, struct sk_buff *skb)
+{
+ u32 match_mark = skb->mark & bat_priv->noflood_mark_mask;
+
+ return bat_priv->noflood_mark_mask &&
+ match_mark == bat_priv->noflood_mark;
+}
+
static netdev_tx_t batadv_interface_tx(struct sk_buff *skb,
struct net_device *soft_iface)
{
@@ -326,6 +343,9 @@ static netdev_tx_t batadv_interface_tx(struct sk_buff *skb,
if (batadv_dat_snoop_outgoing_arp_request(bat_priv, skb))
brd_delay = msecs_to_jiffies(ARP_REQ_DELAY);

+ if (batadv_skb_has_noflood_mark(bat_priv, skb))
+ goto dropped;
+
if (batadv_skb_head_push(skb, sizeof(*bcast_packet)) < 0)
goto dropped;

diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h
index 74b64473..325a41a8 100644
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -1592,6 +1592,18 @@ struct batadv_priv {
*/
u32 isolation_mark_mask;

+ /**
+ * @noflood_mark: the skb->mark value used to allow directed targeting
+ * only
+ */
+ u32 noflood_mark;
+
+ /**
+ * @noflood_mark_mask: bitmask identifying the bits in skb->mark to be
+ * used for the noflood mark
+ */
+ u32 noflood_mark_mask;
+
/** @bcast_seqno: last sent broadcast packet sequence number */
atomic_t bcast_seqno;

--
2.20.1