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batman-adv: protect softif_neigh by rcu
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Add get/set wrapper functions for softif_neigh and
use rcu functions to manipulate the pointers.

Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
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Simon Wunderlich authored and Sven Eckelmann committed Apr 17, 2011
1 parent c4aac1a commit ba85fac
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Showing 2 changed files with 88 additions and 28 deletions.
114 changes: 87 additions & 27 deletions net/batman-adv/soft-interface.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -90,10 +90,51 @@ static void softif_neigh_free_ref(struct softif_neigh *softif_neigh)
call_rcu(&softif_neigh->rcu, softif_neigh_free_rcu);
}

static struct softif_neigh *softif_neigh_get_selected(struct bat_priv *bat_priv)
{
struct softif_neigh *neigh;

rcu_read_lock();
neigh = rcu_dereference(bat_priv->softif_neigh);

if (neigh && !atomic_inc_not_zero(&neigh->refcount))
neigh = NULL;

rcu_read_unlock();
return neigh;
}

static void softif_neigh_select(struct bat_priv *bat_priv,
struct softif_neigh *new_neigh)
{
struct softif_neigh *curr_neigh;

spin_lock_bh(&bat_priv->softif_neigh_lock);

if (new_neigh && !atomic_inc_not_zero(&new_neigh->refcount))
new_neigh = NULL;

curr_neigh = bat_priv->softif_neigh;
rcu_assign_pointer(bat_priv->softif_neigh, new_neigh);

if (curr_neigh)
softif_neigh_free_ref(curr_neigh);

spin_unlock_bh(&bat_priv->softif_neigh_lock);
}

static void softif_neigh_deselect(struct bat_priv *bat_priv)
{
softif_neigh_select(bat_priv, NULL);
}

void softif_neigh_purge(struct bat_priv *bat_priv)
{
struct softif_neigh *softif_neigh, *softif_neigh_tmp;
struct softif_neigh *softif_neigh, *curr_softif_neigh;
struct hlist_node *node, *node_tmp;
char do_deselect = 0;

curr_softif_neigh = softif_neigh_get_selected(bat_priv);

spin_lock_bh(&bat_priv->softif_neigh_lock);

Expand All @@ -105,22 +146,26 @@ void softif_neigh_purge(struct bat_priv *bat_priv)
(atomic_read(&bat_priv->mesh_state) == MESH_ACTIVE))
continue;

hlist_del_rcu(&softif_neigh->list);

if (bat_priv->softif_neigh == softif_neigh) {
if (curr_softif_neigh == softif_neigh) {
bat_dbg(DBG_ROUTES, bat_priv,
"Current mesh exit point '%pM' vanished "
"(vid: %d).\n",
softif_neigh->addr, softif_neigh->vid);
softif_neigh_tmp = bat_priv->softif_neigh;
bat_priv->softif_neigh = NULL;
softif_neigh_free_ref(softif_neigh_tmp);
do_deselect = 1;
}

hlist_del_rcu(&softif_neigh->list);
softif_neigh_free_ref(softif_neigh);
}

spin_unlock_bh(&bat_priv->softif_neigh_lock);

/* soft_neigh_deselect() needs to acquire the softif_neigh_lock */
if (do_deselect)
softif_neigh_deselect(bat_priv);

if (curr_softif_neigh)
softif_neigh_free_ref(curr_softif_neigh);
}

static struct softif_neigh *softif_neigh_get(struct bat_priv *bat_priv,
Expand Down Expand Up @@ -171,6 +216,7 @@ int softif_neigh_seq_print_text(struct seq_file *seq, void *offset)
struct bat_priv *bat_priv = netdev_priv(net_dev);
struct softif_neigh *softif_neigh;
struct hlist_node *node;
struct softif_neigh *curr_softif_neigh;

if (!bat_priv->primary_if) {
return seq_printf(seq, "BATMAN mesh %s disabled - "
Expand All @@ -180,14 +226,17 @@ int softif_neigh_seq_print_text(struct seq_file *seq, void *offset)

seq_printf(seq, "Softif neighbor list (%s)\n", net_dev->name);

curr_softif_neigh = softif_neigh_get_selected(bat_priv);
rcu_read_lock();
hlist_for_each_entry_rcu(softif_neigh, node,
&bat_priv->softif_neigh_list, list)
seq_printf(seq, "%s %pM (vid: %d)\n",
bat_priv->softif_neigh == softif_neigh
curr_softif_neigh == softif_neigh
? "=>" : " ", softif_neigh->addr,
softif_neigh->vid);
rcu_read_unlock();
if (curr_softif_neigh)
softif_neigh_free_ref(curr_softif_neigh);

return 0;
}
Expand All @@ -198,7 +247,8 @@ static void softif_batman_recv(struct sk_buff *skb, struct net_device *dev,
struct bat_priv *bat_priv = netdev_priv(dev);
struct ethhdr *ethhdr = (struct ethhdr *)skb->data;
struct batman_packet *batman_packet;
struct softif_neigh *softif_neigh, *softif_neigh_tmp;
struct softif_neigh *softif_neigh;
struct softif_neigh *curr_softif_neigh = NULL;

if (ntohs(ethhdr->h_proto) == ETH_P_8021Q)
batman_packet = (struct batman_packet *)
Expand All @@ -223,7 +273,8 @@ static void softif_batman_recv(struct sk_buff *skb, struct net_device *dev,
if (!softif_neigh)
goto err;

if (bat_priv->softif_neigh == softif_neigh)
curr_softif_neigh = softif_neigh_get_selected(bat_priv);
if (curr_softif_neigh == softif_neigh)
goto out;

/* we got a neighbor but its mac is 'bigger' than ours */
Expand All @@ -232,38 +283,39 @@ static void softif_batman_recv(struct sk_buff *skb, struct net_device *dev,
goto out;

/* switch to new 'smallest neighbor' */
if ((bat_priv->softif_neigh) &&
(memcmp(softif_neigh->addr, bat_priv->softif_neigh->addr,
if ((curr_softif_neigh) &&
(memcmp(softif_neigh->addr, curr_softif_neigh->addr,
ETH_ALEN) < 0)) {
bat_dbg(DBG_ROUTES, bat_priv,
"Changing mesh exit point from %pM (vid: %d) "
"to %pM (vid: %d).\n",
bat_priv->softif_neigh->addr,
bat_priv->softif_neigh->vid,
curr_softif_neigh->addr,
curr_softif_neigh->vid,
softif_neigh->addr, softif_neigh->vid);
softif_neigh_tmp = bat_priv->softif_neigh;
bat_priv->softif_neigh = softif_neigh;
softif_neigh_free_ref(softif_neigh_tmp);
/* we need to hold the additional reference */
goto err;

softif_neigh_select(bat_priv, softif_neigh);
goto out;
}

/* close own batX device and use softif_neigh as exit node */
if ((!bat_priv->softif_neigh) &&
if ((!curr_softif_neigh) &&
(memcmp(softif_neigh->addr,
bat_priv->primary_if->net_dev->dev_addr, ETH_ALEN) < 0)) {
bat_dbg(DBG_ROUTES, bat_priv,
"Setting mesh exit point to %pM (vid: %d).\n",
softif_neigh->addr, softif_neigh->vid);
bat_priv->softif_neigh = softif_neigh;
/* we need to hold the additional reference */
goto err;

softif_neigh_select(bat_priv, softif_neigh);
goto out;
}

out:
softif_neigh_free_ref(softif_neigh);
err:
kfree_skb(skb);
if (curr_softif_neigh)
softif_neigh_free_ref(curr_softif_neigh);

return;
}

Expand Down Expand Up @@ -321,6 +373,7 @@ int interface_tx(struct sk_buff *skb, struct net_device *soft_iface)
struct bat_priv *bat_priv = netdev_priv(soft_iface);
struct bcast_packet *bcast_packet;
struct vlan_ethhdr *vhdr;
struct softif_neigh *curr_softif_neigh = NULL;
int data_len = skb->len, ret;
short vid = -1;
bool do_bcast = false;
Expand Down Expand Up @@ -348,7 +401,8 @@ int interface_tx(struct sk_buff *skb, struct net_device *soft_iface)
* if we have a another chosen mesh exit node in range
* it will transport the packets to the mesh
*/
if ((bat_priv->softif_neigh) && (bat_priv->softif_neigh->vid == vid))
curr_softif_neigh = softif_neigh_get_selected(bat_priv);
if ((curr_softif_neigh) && (curr_softif_neigh->vid == vid))
goto dropped;

/* TODO: check this for locks */
Expand Down Expand Up @@ -410,6 +464,8 @@ int interface_tx(struct sk_buff *skb, struct net_device *soft_iface)
dropped_freed:
bat_priv->stats.tx_dropped++;
end:
if (curr_softif_neigh)
softif_neigh_free_ref(curr_softif_neigh);
return NETDEV_TX_OK;
}

Expand All @@ -421,6 +477,7 @@ void interface_rx(struct net_device *soft_iface,
struct unicast_packet *unicast_packet;
struct ethhdr *ethhdr;
struct vlan_ethhdr *vhdr;
struct softif_neigh *curr_softif_neigh = NULL;
short vid = -1;
int ret;

Expand Down Expand Up @@ -450,7 +507,8 @@ void interface_rx(struct net_device *soft_iface,
* if we have a another chosen mesh exit node in range
* it will transport the packets to the non-mesh network
*/
if ((bat_priv->softif_neigh) && (bat_priv->softif_neigh->vid == vid)) {
curr_softif_neigh = softif_neigh_get_selected(bat_priv);
if (curr_softif_neigh && (curr_softif_neigh->vid == vid)) {
skb_push(skb, hdr_size);
unicast_packet = (struct unicast_packet *)skb->data;

Expand All @@ -461,7 +519,7 @@ void interface_rx(struct net_device *soft_iface,
skb_reset_mac_header(skb);

memcpy(unicast_packet->dest,
bat_priv->softif_neigh->addr, ETH_ALEN);
curr_softif_neigh->addr, ETH_ALEN);
ret = route_unicast_packet(skb, recv_if);
if (ret == NET_RX_DROP)
goto dropped;
Expand All @@ -486,11 +544,13 @@ void interface_rx(struct net_device *soft_iface,
soft_iface->last_rx = jiffies;

netif_rx(skb);
return;
goto out;

dropped:
kfree_skb(skb);
out:
if (curr_softif_neigh)
softif_neigh_free_ref(curr_softif_neigh);
return;
}

Expand Down
2 changes: 1 addition & 1 deletion net/batman-adv/types.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -147,7 +147,7 @@ struct bat_priv {
atomic_t batman_queue_left;
char num_ifaces;
struct hlist_head softif_neigh_list;
struct softif_neigh *softif_neigh;
struct softif_neigh __rcu *softif_neigh;
struct debug_log *debug_log;
struct hard_iface *primary_if;
struct kobject *mesh_obj;
Expand Down

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