[B.A.T.M.A.N.] [PATCH 28/28] batman-adv: Disallow regular interface as mesh device

Sven Eckelmann
2011-03-05T12:28:42Z

When trying to associate a net_device with another net_device which
already exists, batman-adv assumes that this interface is a fully
initialized batman mesh interface without checking it. The behaviour
when accessing data behind netdev_priv of a random net_device is
undefined and potentially dangerous.

Reported-by: Linus Lüssing <linus.luessing@ascom.ch>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
---
net/batman-adv/hard-interface.c | 34 ++++++++++++++++++++++------------
net/batman-adv/soft-interface.c | 13 +++++++++++++
net/batman-adv/soft-interface.h | 1 +
3 files changed, 36 insertions(+), 12 deletions(-)

diff --git a/net/batman-adv/hard-interface.c b/net/batman-adv/hard-interface.c
index 95a35b6..b3058e4 100644
--- a/net/batman-adv/hard-interface.c
+++ b/net/batman-adv/hard-interface.c
@@ -79,13 +79,8 @@ static int is_valid_iface(struct net_device *net_dev)
return 0;

/* no batman over batman */
-#ifdef HAVE_NET_DEVICE_OPS
- if (net_dev->netdev_ops->ndo_start_xmit == interface_tx)
+ if (softif_is_valid(net_dev))
return 0;
-#else
- if (net_dev->hard_start_xmit == interface_tx)
- return 0;
-#endif

/* Device is being bridged */
/* if (net_dev->priv_flags & IFF_BRIDGE_PORT)
@@ -282,6 +277,8 @@ int hardif_enable_interface(struct hard_iface *hard_iface, char *iface_name)
{
struct bat_priv *bat_priv;
struct batman_packet *batman_packet;
+ struct net_device *soft_iface;
+ int ret;

if (hard_iface->if_status != IF_NOT_IN_USE)
goto out;
@@ -289,18 +286,30 @@ int hardif_enable_interface(struct hard_iface *hard_iface, char *iface_name)
if (!atomic_inc_not_zero(&hard_iface->refcount))
goto out;

- hard_iface->soft_iface = dev_get_by_name(&init_net, iface_name);
+ soft_iface = dev_get_by_name(&init_net, iface_name);

- if (!hard_iface->soft_iface) {
- hard_iface->soft_iface = softif_create(iface_name);
+ if (!soft_iface) {
+ soft_iface = softif_create(iface_name);

- if (!hard_iface->soft_iface)
+ if (!soft_iface) {
+ ret = -ENOMEM;
goto err;
+ }

/* dev_get_by_name() increases the reference counter for us */
- dev_hold(hard_iface->soft_iface);
+ dev_hold(soft_iface);
+ }
+
+ if (!softif_is_valid(soft_iface)) {
+ pr_err("Can't create batman mesh interface %s: "
+ "already exists as regular interface\n",
+ soft_iface->name);
+ dev_put(soft_iface);
+ ret = -EINVAL;
+ goto err;
}

+ hard_iface->soft_iface = soft_iface;
bat_priv = netdev_priv(hard_iface->soft_iface);
hard_iface->packet_len = BAT_PACKET_LEN;
hard_iface->packet_buff = kmalloc(hard_iface->packet_len, GFP_ATOMIC);
@@ -308,6 +317,7 @@ int hardif_enable_interface(struct hard_iface *hard_iface, char *iface_name)
if (!hard_iface->packet_buff) {
bat_err(hard_iface->soft_iface, "Can't add interface packet "
"(%s): out of memory\n", hard_iface->net_dev->name);
+ ret = -ENOMEM;
goto err;
}

@@ -370,7 +380,7 @@ out:

err:
hardif_free_ref(hard_iface);
- return -ENOMEM;
+ return ret;
}

void hardif_disable_interface(struct hard_iface *hard_iface)
diff --git a/net/batman-adv/soft-interface.c b/net/batman-adv/soft-interface.c
index 6b514ec..9ed2614 100644
--- a/net/batman-adv/soft-interface.c
+++ b/net/batman-adv/soft-interface.c
@@ -622,6 +622,19 @@ void softif_destroy(struct net_device *soft_iface)
unregister_netdevice(soft_iface);
}

+int softif_is_valid(struct net_device *net_dev)
+{
+#ifdef HAVE_NET_DEVICE_OPS
+ if (net_dev->netdev_ops->ndo_start_xmit == interface_tx)
+ return 1;
+#else
+ if (net_dev->hard_start_xmit == interface_tx)
+ return 1;
+#endif
+
+ return 0;
+}
+
/* ethtool */
static int bat_get_settings(struct net_device *dev, struct ethtool_cmd *cmd)
{
diff --git a/net/batman-adv/soft-interface.h b/net/batman-adv/soft-interface.h
index 80a3607..4789b6f 100644
--- a/net/batman-adv/soft-interface.h
+++ b/net/batman-adv/soft-interface.h
@@ -31,5 +31,6 @@ void interface_rx(struct net_device *soft_iface,
int hdr_size);
struct net_device *softif_create(char *name);
void softif_destroy(struct net_device *soft_iface);
+int softif_is_valid(struct net_device *net_dev);

#endif /* _NET_BATMAN_ADV_SOFT_INTERFACE_H_ */
--
1.7.2.3