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batman-adv: mcast: apply optimizations for routable packets, too
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Now that we not only track the presence of multicast listeners but also
multicast routers we can safely apply group-aware multicast-to-unicast
forwarding to packets with a destination address of scope greater than
link-local as well.

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 Jun 27, 2019
1 parent 61caf3d commit 11d458c
Showing 1 changed file with 241 additions and 18 deletions.
259 changes: 241 additions & 18 deletions net/batman-adv/multicast.c
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Original file line number Diff line number Diff line change
Expand Up @@ -980,6 +980,7 @@ static bool batadv_mcast_is_report_ipv4(struct sk_buff *skb)
* @bat_priv: the bat priv with all the soft interface information
* @skb: the IPv4 packet to check
* @is_unsnoopable: stores whether the destination is snoopable
* @is_routable: stores whether the destination is routable
*
* Checks whether the given IPv4 packet has the potential to be forwarded with a
* mode more optimal than classic flooding.
Expand All @@ -989,7 +990,8 @@ static bool batadv_mcast_is_report_ipv4(struct sk_buff *skb)
*/
static int batadv_mcast_forw_mode_check_ipv4(struct batadv_priv *bat_priv,
struct sk_buff *skb,
bool *is_unsnoopable)
bool *is_unsnoopable,
int *is_routable)
{
struct iphdr *iphdr;

Expand All @@ -1002,16 +1004,13 @@ static int batadv_mcast_forw_mode_check_ipv4(struct batadv_priv *bat_priv,

iphdr = ip_hdr(skb);

/* TODO: Implement Multicast Router Discovery (RFC4286),
* then allow scope > link local, too
*/
if (!ipv4_is_local_multicast(iphdr->daddr))
return -EINVAL;

/* link-local multicast listeners behind a bridge are
* not snoopable (see RFC4541, section 2.1.2.2)
*/
*is_unsnoopable = true;
if (ipv4_is_local_multicast(iphdr->daddr))
*is_unsnoopable = true;
else
*is_routable = ETH_P_IP;

return 0;
}
Expand Down Expand Up @@ -1046,6 +1045,7 @@ static bool batadv_mcast_is_report_ipv6(struct sk_buff *skb)
* @bat_priv: the bat priv with all the soft interface information
* @skb: the IPv6 packet to check
* @is_unsnoopable: stores whether the destination is snoopable
* @is_routable: stores whether the destination is routable
*
* Checks whether the given IPv6 packet has the potential to be forwarded with a
* mode more optimal than classic flooding.
Expand All @@ -1054,7 +1054,8 @@ static bool batadv_mcast_is_report_ipv6(struct sk_buff *skb)
*/
static int batadv_mcast_forw_mode_check_ipv6(struct batadv_priv *bat_priv,
struct sk_buff *skb,
bool *is_unsnoopable)
bool *is_unsnoopable,
int *is_routable)
{
struct ipv6hdr *ip6hdr;

Expand All @@ -1067,17 +1068,16 @@ static int batadv_mcast_forw_mode_check_ipv6(struct batadv_priv *bat_priv,

ip6hdr = ipv6_hdr(skb);

/* TODO: Implement Multicast Router Discovery (RFC4286),
* then allow scope > link local, too
*/
if (IPV6_ADDR_MC_SCOPE(&ip6hdr->daddr) != IPV6_ADDR_SCOPE_LINKLOCAL)
if (IPV6_ADDR_MC_SCOPE(&ip6hdr->daddr) < IPV6_ADDR_SCOPE_LINKLOCAL)
return -EINVAL;

/* link-local-all-nodes multicast listeners behind a bridge are
* not snoopable (see RFC4541, section 3, paragraph 3)
*/
if (ipv6_addr_is_ll_all_nodes(&ip6hdr->daddr))
*is_unsnoopable = true;
else if (IPV6_ADDR_MC_SCOPE(&ip6hdr->daddr) > IPV6_ADDR_SCOPE_LINKLOCAL)
*is_routable = ETH_P_IPV6;

return 0;
}
Expand All @@ -1087,6 +1087,7 @@ static int batadv_mcast_forw_mode_check_ipv6(struct batadv_priv *bat_priv,
* @bat_priv: the bat priv with all the soft interface information
* @skb: the multicast frame to check
* @is_unsnoopable: stores whether the destination is snoopable
* @is_routable: stores whether the destination is routable
*
* Checks whether the given multicast ethernet frame has the potential to be
* forwarded with a mode more optimal than classic flooding.
Expand All @@ -1095,7 +1096,8 @@ static int batadv_mcast_forw_mode_check_ipv6(struct batadv_priv *bat_priv,
*/
static int batadv_mcast_forw_mode_check(struct batadv_priv *bat_priv,
struct sk_buff *skb,
bool *is_unsnoopable)
bool *is_unsnoopable,
int *is_routable)
{
struct ethhdr *ethhdr = eth_hdr(skb);

Expand All @@ -1105,13 +1107,15 @@ static int batadv_mcast_forw_mode_check(struct batadv_priv *bat_priv,
switch (ntohs(ethhdr->h_proto)) {
case ETH_P_IP:
return batadv_mcast_forw_mode_check_ipv4(bat_priv, skb,
is_unsnoopable);
is_unsnoopable,
is_routable);
case ETH_P_IPV6:
if (!IS_ENABLED(CONFIG_IPV6))
return -EINVAL;

return batadv_mcast_forw_mode_check_ipv6(bat_priv, skb,
is_unsnoopable);
is_unsnoopable,
is_routable);
default:
return -EINVAL;
}
Expand Down Expand Up @@ -1141,6 +1145,29 @@ static int batadv_mcast_forw_want_all_ip_count(struct batadv_priv *bat_priv,
}
}

/**
* batadv_mcast_forw_rtr_count() - count nodes with a multicast router
* @bat_priv: the bat priv with all the soft interface information
* @protocol: the ethernet protocol type to count multicast routers for
*
* Return: the number of nodes which want all routable IPv4 multicast traffic
* if the protocol is ETH_P_IP or the number of nodes which want all routable
* IPv6 traffic if the protocol is ETH_P_IPV6. Otherwise returns 0.
*/

static int batadv_mcast_forw_rtr_count(struct batadv_priv *bat_priv,
int protocol)
{
switch (protocol) {
case ETH_P_IP:
return atomic_read(&bat_priv->mcast.num_want_all_rtr4);
case ETH_P_IPV6:
return atomic_read(&bat_priv->mcast.num_want_all_rtr6);
default:
return 0;
}
}

/**
* batadv_mcast_forw_tt_node_get() - get a multicast tt node
* @bat_priv: the bat priv with all the soft interface information
Expand Down Expand Up @@ -1262,6 +1289,84 @@ batadv_mcast_forw_unsnoop_node_get(struct batadv_priv *bat_priv)
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
Expand All @@ -1280,8 +1385,11 @@ batadv_mcast_forw_mode(struct batadv_priv *bat_priv, struct sk_buff *skb,
bool is_unsnoopable = false;
unsigned int mcast_fanout;
struct ethhdr *ethhdr;
int is_routable = 0;
int rtr_count = 0;

ret = batadv_mcast_forw_mode_check(bat_priv, skb, &is_unsnoopable);
ret = batadv_mcast_forw_mode_check(bat_priv, skb, &is_unsnoopable,
&is_routable);
if (ret == -ENOMEM)
return BATADV_FORW_NONE;
else if (ret < 0)
Expand All @@ -1294,8 +1402,9 @@ batadv_mcast_forw_mode(struct batadv_priv *bat_priv, struct sk_buff *skb,
ip_count = batadv_mcast_forw_want_all_ip_count(bat_priv, ethhdr);
unsnoop_count = !is_unsnoopable ? 0 :
atomic_read(&bat_priv->mcast.num_want_all_unsnoopables);
rtr_count = batadv_mcast_forw_rtr_count(bat_priv, is_routable);

total_count = tt_count + ip_count + unsnoop_count;
total_count = tt_count + ip_count + unsnoop_count + rtr_count;

switch (total_count) {
case 1:
Expand All @@ -1305,6 +1414,9 @@ batadv_mcast_forw_mode(struct batadv_priv *bat_priv, struct sk_buff *skb,
*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;
Expand Down Expand Up @@ -1475,6 +1587,111 @@ batadv_mcast_forw_want_all(struct batadv_priv *bat_priv,
}
}

/**
* batadv_mcast_forw_want_all_rtr4() - forward to nodes with want-all-rtr4
* @bat_priv: the bat priv with all the soft interface information
* @skb: the multicast packet to transmit
* @vid: the vlan identifier
*
* Sends copies of a frame with multicast destination to any node with a
* BATADV_MCAST_WANT_NO_RTR4 flag unset. A transmission is performed via a
* batman-adv unicast packet for each such destination node.
*
* Return: NET_XMIT_DROP on memory allocation failure, NET_XMIT_SUCCESS
* otherwise.
*/
static int
batadv_mcast_forw_want_all_rtr4(struct batadv_priv *bat_priv,
struct sk_buff *skb, unsigned short vid)
{
struct batadv_orig_node *orig_node;
int ret = NET_XMIT_SUCCESS;
struct sk_buff *newskb;

rcu_read_lock();
hlist_for_each_entry_rcu(orig_node,
&bat_priv->mcast.want_all_rtr4_list,
mcast_want_all_rtr4_node) {
newskb = skb_copy(skb, GFP_ATOMIC);
if (!newskb) {
ret = NET_XMIT_DROP;
break;
}

batadv_send_skb_unicast(bat_priv, newskb, BATADV_UNICAST, 0,
orig_node, vid);
}
rcu_read_unlock();
return ret;
}

/**
* batadv_mcast_forw_want_all_rtr6() - forward to nodes with want-all-rtr6
* @bat_priv: the bat priv with all the soft interface information
* @skb: The multicast packet to transmit
* @vid: the vlan identifier
*
* Sends copies of a frame with multicast destination to any node with a
* BATADV_MCAST_WANT_NO_RTR6 flag unset. A transmission is performed via a
* batman-adv unicast packet for each such destination node.
*
* Return: NET_XMIT_DROP on memory allocation failure, NET_XMIT_SUCCESS
* otherwise.
*/
static int
batadv_mcast_forw_want_all_rtr6(struct batadv_priv *bat_priv,
struct sk_buff *skb, unsigned short vid)
{
struct batadv_orig_node *orig_node;
int ret = NET_XMIT_SUCCESS;
struct sk_buff *newskb;

rcu_read_lock();
hlist_for_each_entry_rcu(orig_node,
&bat_priv->mcast.want_all_rtr6_list,
mcast_want_all_rtr6_node) {
newskb = skb_copy(skb, GFP_ATOMIC);
if (!newskb) {
ret = NET_XMIT_DROP;
break;
}

batadv_send_skb_unicast(bat_priv, newskb, BATADV_UNICAST, 0,
orig_node, vid);
}
rcu_read_unlock();
return ret;
}

/**
* batadv_mcast_forw_want_rtr() - forward packet to nodes in a want-all-rtr list
* @bat_priv: the bat priv with all the soft interface information
* @skb: the multicast packet to transmit
* @vid: the vlan identifier
*
* Sends copies of a frame with multicast destination to any node with a
* BATADV_MCAST_WANT_NO_RTR4 or BATADV_MCAST_WANT_NO_RTR6 flag unset. A
* transmission is performed via a batman-adv unicast packet for each such
* destination node.
*
* Return: NET_XMIT_DROP on memory allocation failure or if the protocol family
* is neither IPv4 nor IPv6. NET_XMIT_SUCCESS otherwise.
*/
static int
batadv_mcast_forw_want_rtr(struct batadv_priv *bat_priv,
struct sk_buff *skb, unsigned short vid)
{
switch (ntohs(eth_hdr(skb)->h_proto)) {
case ETH_P_IP:
return batadv_mcast_forw_want_all_rtr4(bat_priv, skb, vid);
case ETH_P_IPV6:
return batadv_mcast_forw_want_all_rtr6(bat_priv, skb, vid);
default:
/* we shouldn't be here... */
return NET_XMIT_DROP;
}
}

/**
* batadv_mcast_forw_send() - send packet to any detected multicast recpient
* @bat_priv: the bat priv with all the soft interface information
Expand Down Expand Up @@ -1508,6 +1725,12 @@ int batadv_mcast_forw_send(struct batadv_priv *bat_priv, struct sk_buff *skb,
return ret;
}

ret = batadv_mcast_forw_want_rtr(bat_priv, skb, vid);
if (ret != NET_XMIT_SUCCESS) {
kfree_skb(skb);
return ret;
}

consume_skb(skb);
return ret;
}
Expand Down

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