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batman-adv: mcast: remove now redundant single ucast forwarding
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The multicast code to send a multicast packet via multiple batman-adv
unicast packets is not only capable of sending to multiple but also to a
single node. Therefore we can safely remove the old, specialized, now
redundant multicast-to-single-unicast code.

The only functional change of this simplification is that the edge case
of allowing a multicast packet with an unsnoopable destination address
(224.0.0.0/24 or ff02::1) where only a single node has signaled interest
in it via the batman-adv want-all-unsnoopables multicast flag is now
transmitted via a batman-adv broadcast instead of a batman-adv unicast
packet. Maintaining this edge case feature does not seem worth the extra
lines of code and people should just not expect to be able to snoop and
optimize such unsnoopable multicast addresses when bridges are involved.

While at it also renaming a few items in the batadv_forw_mode enum to
prepare for the new batman-adv multicast packet type.

Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
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Linus Lüssing authored and Simon Wunderlich committed Jan 21, 2023
1 parent 8f6bc45 commit e7d6127
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Showing 3 changed files with 33 additions and 280 deletions.
249 changes: 14 additions & 235 deletions net/batman-adv/multicast.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -26,7 +26,6 @@
#include <linux/ipv6.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/kref.h>
#include <linux/list.h>
#include <linux/lockdep.h>
#include <linux/netdevice.h>
Expand Down Expand Up @@ -1136,223 +1135,20 @@ static int batadv_mcast_forw_rtr_count(struct batadv_priv *bat_priv,
}
}

/**
* batadv_mcast_forw_tt_node_get() - get a multicast tt node
* @bat_priv: the bat priv with all the soft interface information
* @ethhdr: the ether header containing the multicast destination
*
* Return: an orig_node matching the multicast address provided by ethhdr
* via a translation table lookup. This increases the returned nodes refcount.
*/
static struct batadv_orig_node *
batadv_mcast_forw_tt_node_get(struct batadv_priv *bat_priv,
struct ethhdr *ethhdr)
{
return batadv_transtable_search(bat_priv, NULL, ethhdr->h_dest,
BATADV_NO_FLAGS);
}

/**
* batadv_mcast_forw_ipv4_node_get() - get a node with an ipv4 flag
* @bat_priv: the bat priv with all the soft interface information
*
* Return: an orig_node which has the BATADV_MCAST_WANT_ALL_IPV4 flag set and
* increases its refcount.
*/
static struct batadv_orig_node *
batadv_mcast_forw_ipv4_node_get(struct batadv_priv *bat_priv)
{
struct batadv_orig_node *tmp_orig_node, *orig_node = NULL;

rcu_read_lock();
hlist_for_each_entry_rcu(tmp_orig_node,
&bat_priv->mcast.want_all_ipv4_list,
mcast_want_all_ipv4_node) {
if (!kref_get_unless_zero(&tmp_orig_node->refcount))
continue;

orig_node = tmp_orig_node;
break;
}
rcu_read_unlock();

return orig_node;
}

/**
* batadv_mcast_forw_ipv6_node_get() - get a node with an ipv6 flag
* @bat_priv: the bat priv with all the soft interface information
*
* Return: an orig_node which has the BATADV_MCAST_WANT_ALL_IPV6 flag set
* and increases its refcount.
*/
static struct batadv_orig_node *
batadv_mcast_forw_ipv6_node_get(struct batadv_priv *bat_priv)
{
struct batadv_orig_node *tmp_orig_node, *orig_node = NULL;

rcu_read_lock();
hlist_for_each_entry_rcu(tmp_orig_node,
&bat_priv->mcast.want_all_ipv6_list,
mcast_want_all_ipv6_node) {
if (!kref_get_unless_zero(&tmp_orig_node->refcount))
continue;

orig_node = tmp_orig_node;
break;
}
rcu_read_unlock();

return orig_node;
}

/**
* batadv_mcast_forw_ip_node_get() - get a node with an ipv4/ipv6 flag
* @bat_priv: the bat priv with all the soft interface information
* @ethhdr: an ethernet header to determine the protocol family from
*
* Return: an orig_node which has the BATADV_MCAST_WANT_ALL_IPV4 or
* BATADV_MCAST_WANT_ALL_IPV6 flag, depending on the provided ethhdr, sets and
* increases its refcount.
*/
static struct batadv_orig_node *
batadv_mcast_forw_ip_node_get(struct batadv_priv *bat_priv,
struct ethhdr *ethhdr)
{
switch (ntohs(ethhdr->h_proto)) {
case ETH_P_IP:
return batadv_mcast_forw_ipv4_node_get(bat_priv);
case ETH_P_IPV6:
return batadv_mcast_forw_ipv6_node_get(bat_priv);
default:
/* we shouldn't be here... */
return NULL;
}
}

/**
* batadv_mcast_forw_unsnoop_node_get() - get a node with an unsnoopable flag
* @bat_priv: the bat priv with all the soft interface information
*
* Return: an orig_node which has the BATADV_MCAST_WANT_ALL_UNSNOOPABLES flag
* set and increases its refcount.
*/
static struct batadv_orig_node *
batadv_mcast_forw_unsnoop_node_get(struct batadv_priv *bat_priv)
{
struct batadv_orig_node *tmp_orig_node, *orig_node = NULL;

rcu_read_lock();
hlist_for_each_entry_rcu(tmp_orig_node,
&bat_priv->mcast.want_all_unsnoopables_list,
mcast_want_all_unsnoopables_node) {
if (!kref_get_unless_zero(&tmp_orig_node->refcount))
continue;

orig_node = tmp_orig_node;
break;
}
rcu_read_unlock();

return orig_node;
}

/**
* batadv_mcast_forw_rtr4_node_get() - get a node with an ipv4 mcast router flag
* @bat_priv: the bat priv with all the soft interface information
*
* Return: an orig_node which has the BATADV_MCAST_WANT_NO_RTR4 flag unset and
* increases its refcount.
*/
static struct batadv_orig_node *
batadv_mcast_forw_rtr4_node_get(struct batadv_priv *bat_priv)
{
struct batadv_orig_node *tmp_orig_node, *orig_node = NULL;

rcu_read_lock();
hlist_for_each_entry_rcu(tmp_orig_node,
&bat_priv->mcast.want_all_rtr4_list,
mcast_want_all_rtr4_node) {
if (!kref_get_unless_zero(&tmp_orig_node->refcount))
continue;

orig_node = tmp_orig_node;
break;
}
rcu_read_unlock();

return orig_node;
}

/**
* batadv_mcast_forw_rtr6_node_get() - get a node with an ipv6 mcast router flag
* @bat_priv: the bat priv with all the soft interface information
*
* Return: an orig_node which has the BATADV_MCAST_WANT_NO_RTR6 flag unset
* and increases its refcount.
*/
static struct batadv_orig_node *
batadv_mcast_forw_rtr6_node_get(struct batadv_priv *bat_priv)
{
struct batadv_orig_node *tmp_orig_node, *orig_node = NULL;

rcu_read_lock();
hlist_for_each_entry_rcu(tmp_orig_node,
&bat_priv->mcast.want_all_rtr6_list,
mcast_want_all_rtr6_node) {
if (!kref_get_unless_zero(&tmp_orig_node->refcount))
continue;

orig_node = tmp_orig_node;
break;
}
rcu_read_unlock();

return orig_node;
}

/**
* batadv_mcast_forw_rtr_node_get() - get a node with an ipv4/ipv6 router flag
* @bat_priv: the bat priv with all the soft interface information
* @ethhdr: an ethernet header to determine the protocol family from
*
* Return: an orig_node which has no BATADV_MCAST_WANT_NO_RTR4 or
* BATADV_MCAST_WANT_NO_RTR6 flag, depending on the provided ethhdr, set and
* increases its refcount.
*/
static struct batadv_orig_node *
batadv_mcast_forw_rtr_node_get(struct batadv_priv *bat_priv,
struct ethhdr *ethhdr)
{
switch (ntohs(ethhdr->h_proto)) {
case ETH_P_IP:
return batadv_mcast_forw_rtr4_node_get(bat_priv);
case ETH_P_IPV6:
return batadv_mcast_forw_rtr6_node_get(bat_priv);
default:
/* we shouldn't be here... */
return NULL;
}
}

/**
* batadv_mcast_forw_mode() - check on how to forward a multicast packet
* @bat_priv: the bat priv with all the soft interface information
* @skb: The multicast packet to check
* @orig: an originator to be set to forward the skb to
* @skb: the multicast packet to check
* @is_routable: stores whether the destination is routable
*
* Return: the forwarding mode as enum batadv_forw_mode and in case of
* BATADV_FORW_SINGLE set the orig to the single originator the skb
* should be forwarded to.
* Return: The forwarding mode as enum batadv_forw_mode.
*/
enum batadv_forw_mode
batadv_mcast_forw_mode(struct batadv_priv *bat_priv, struct sk_buff *skb,
struct batadv_orig_node **orig, int *is_routable)
int *is_routable)
{
int ret, tt_count, ip_count, unsnoop_count, total_count;
bool is_unsnoopable = false;
unsigned int mcast_fanout;
struct ethhdr *ethhdr;
int rtr_count = 0;

Expand All @@ -1361,7 +1157,7 @@ batadv_mcast_forw_mode(struct batadv_priv *bat_priv, struct sk_buff *skb,
if (ret == -ENOMEM)
return BATADV_FORW_NONE;
else if (ret < 0)
return BATADV_FORW_ALL;
return BATADV_FORW_BCAST;

ethhdr = eth_hdr(skb);

Expand All @@ -1374,32 +1170,15 @@ batadv_mcast_forw_mode(struct batadv_priv *bat_priv, struct sk_buff *skb,

total_count = tt_count + ip_count + unsnoop_count + rtr_count;

switch (total_count) {
case 1:
if (tt_count)
*orig = batadv_mcast_forw_tt_node_get(bat_priv, ethhdr);
else if (ip_count)
*orig = batadv_mcast_forw_ip_node_get(bat_priv, ethhdr);
else if (unsnoop_count)
*orig = batadv_mcast_forw_unsnoop_node_get(bat_priv);
else if (rtr_count)
*orig = batadv_mcast_forw_rtr_node_get(bat_priv,
ethhdr);

if (*orig)
return BATADV_FORW_SINGLE;

fallthrough;
case 0:
if (!total_count)
return BATADV_FORW_NONE;
default:
mcast_fanout = atomic_read(&bat_priv->multicast_fanout);
else if (unsnoop_count)
return BATADV_FORW_BCAST;

if (!unsnoop_count && total_count <= mcast_fanout)
return BATADV_FORW_SOME;
}
if (total_count <= atomic_read(&bat_priv->multicast_fanout))
return BATADV_FORW_UCASTS;

return BATADV_FORW_ALL;
return BATADV_FORW_BCAST;
}

/**
Expand All @@ -1411,10 +1190,10 @@ batadv_mcast_forw_mode(struct batadv_priv *bat_priv, struct sk_buff *skb,
*
* Return: NET_XMIT_DROP in case of error or NET_XMIT_SUCCESS otherwise.
*/
int batadv_mcast_forw_send_orig(struct batadv_priv *bat_priv,
struct sk_buff *skb,
unsigned short vid,
struct batadv_orig_node *orig_node)
static int batadv_mcast_forw_send_orig(struct batadv_priv *bat_priv,
struct sk_buff *skb,
unsigned short vid,
struct batadv_orig_node *orig_node)
{
/* Avoid sending multicast-in-unicast packets to other BLA
* gateways - they already got the frame from the LAN side
Expand Down
38 changes: 7 additions & 31 deletions net/batman-adv/multicast.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -17,23 +17,16 @@
*/
enum batadv_forw_mode {
/**
* @BATADV_FORW_ALL: forward the packet to all nodes (currently via
* classic flooding)
* @BATADV_FORW_BCAST: forward the packet to all nodes via a batman-adv
* broadcast packet
*/
BATADV_FORW_ALL,
BATADV_FORW_BCAST,

/**
* @BATADV_FORW_SOME: forward the packet to some nodes (currently via
* a multicast-to-unicast conversion and the BATMAN unicast routing
* protocol)
* @BATADV_FORW_UCASTS: forward the packet to some nodes via one
* or more batman-adv unicast packets
*/
BATADV_FORW_SOME,

/**
* @BATADV_FORW_SINGLE: forward the packet to a single node (currently
* via the BATMAN unicast routing protocol)
*/
BATADV_FORW_SINGLE,
BATADV_FORW_UCASTS,

/** @BATADV_FORW_NONE: don't forward, drop it */
BATADV_FORW_NONE,
Expand All @@ -43,14 +36,8 @@ enum batadv_forw_mode {

enum batadv_forw_mode
batadv_mcast_forw_mode(struct batadv_priv *bat_priv, struct sk_buff *skb,
struct batadv_orig_node **mcast_single_orig,
int *is_routable);

int batadv_mcast_forw_send_orig(struct batadv_priv *bat_priv,
struct sk_buff *skb,
unsigned short vid,
struct batadv_orig_node *orig_node);

int batadv_mcast_forw_send(struct batadv_priv *bat_priv, struct sk_buff *skb,
unsigned short vid, int is_routable);

Expand All @@ -69,20 +56,9 @@ void batadv_mcast_purge_orig(struct batadv_orig_node *orig_node);

static inline enum batadv_forw_mode
batadv_mcast_forw_mode(struct batadv_priv *bat_priv, struct sk_buff *skb,
struct batadv_orig_node **mcast_single_orig,
int *is_routable)
{
return BATADV_FORW_ALL;
}

static inline int
batadv_mcast_forw_send_orig(struct batadv_priv *bat_priv,
struct sk_buff *skb,
unsigned short vid,
struct batadv_orig_node *orig_node)
{
kfree_skb(skb);
return NET_XMIT_DROP;
return BATADV_FORW_BCAST;
}

static inline int
Expand Down
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