linux-toradex.git/net/l2tp/l2tp_eth.c, branch v4.18-rc7

l2tp: remove .tunnel_sock from struct l2tp_eth

2017-11-11T13:08:23+00:00

This field has never been used.

Signed-off-by: Guillaume Nault 
Signed-off-by: David S. Miller

l2tp: remove field 'dev' from struct l2tp_eth

2017-11-01T01:57:24+00:00

This field has never been used.

Signed-off-by: Guillaume Nault 
Signed-off-by: David S. Miller

l2tp: initialise l2tp_eth sessions before registering them

2017-10-29T02:16:22+00:00

Sessions must be initialised before being made externally visible by
l2tp_session_register(). Otherwise the session may be concurrently
deleted before being initialised, which can confuse the deletion path
and eventually lead to kernel oops.

Therefore, we need to move l2tp_session_register() down in
l2tp_eth_create(), but also handle the intermediate step where only the
session or the netdevice has been registered.

We can't just call l2tp_session_register() in ->ndo_init() because
we'd have no way to properly undo this operation in ->ndo_uninit().
Instead, let's register the session and the netdevice in two different
steps and protect the session's device pointer with RCU.

And now that we allow the session's .dev field to be NULL, we don't
need to prevent the netdevice from being removed anymore. So we can
drop the dev_hold() and dev_put() calls in l2tp_eth_create() and
l2tp_eth_dev_uninit().

Fixes: d9e31d17ceba ("l2tp: Add L2TP ethernet pseudowire support")
Signed-off-by: Guillaume Nault 
Signed-off-by: David S. Miller

l2tp: don't register sessions in l2tp_session_create()

2017-10-29T02:16:21+00:00

Sessions created by l2tp_session_create() aren't fully initialised:
some pseudo-wire specific operations need to be done before making the
session usable. Therefore the PPP and Ethernet pseudo-wires continue
working on the returned l2tp session while it's already been exposed to
the rest of the system.
This can lead to various issues. In particular, the session may enter
the deletion process before having been fully initialised, which will
confuse the session removal code.

This patch moves session registration out of l2tp_session_create(), so
that callers can control when the session is exposed to the rest of the
system. This is done by the new l2tp_session_register() function.

Only pppol2tp_session_create() can be easily converted to avoid
modifying its session after registration (the debug message is dropped
in order to avoid the need for holding a reference on the session).

For pppol2tp_connect() and l2tp_eth_create()), more work is needed.
That'll be done in followup patches. For now, let's just register the
session right after its creation, like it was done before. The only
difference is that we can easily take a reference on the session before
registering it, so, at least, we're sure it's not going to be freed
while we're working on it.

Signed-off-by: Guillaume Nault 
Signed-off-by: David S. Miller

l2tp: fix l2tp_eth module loading

2017-10-02T05:35:07+00:00

The l2tp_eth module crashes if its netlink callbacks are run when the
pernet data aren't initialised.

We should normally register_pernet_device() before the genl callbacks.
However, the pernet data only maintain a list of l2tpeth interfaces,
and this list is never used. So let's just drop pernet handling
instead.

Fixes: d9e31d17ceba ("l2tp: Add L2TP ethernet pseudowire support")
Signed-off-by: Guillaume Nault 
Signed-off-by: David S. Miller

l2tp: pass tunnel pointer to ->session_create()

2017-09-03T18:04:21+00:00

Using l2tp_tunnel_find() in pppol2tp_session_create() and
l2tp_eth_create() is racy, because no reference is held on the
returned session. These functions are only used to implement the
->session_create callback which is run by l2tp_nl_cmd_session_create().
Therefore searching for the parent tunnel isn't necessary because
l2tp_nl_cmd_session_create() already has a pointer to it and holds a
reference.

This patch modifies ->session_create()'s prototype to directly pass the
the parent tunnel as parameter, thus avoiding searching for it in
pppol2tp_session_create() and l2tp_eth_create().

Since we have to touch the ->session_create() call in
l2tp_nl_cmd_session_create(), let's also remove the useless conditional:
we know that ->session_create isn't NULL at this point because it's
already been checked earlier in this same function.

Finally, one might be tempted to think that the removed
l2tp_tunnel_find() calls were harmless because they would return the
same tunnel as the one held by l2tp_nl_cmd_session_create() anyway.
But that tunnel might be removed and a new one created with same tunnel
Id before the l2tp_tunnel_find() call. In this case l2tp_tunnel_find()
would return the new tunnel which wouldn't be protected by the
reference held by l2tp_nl_cmd_session_create().

Fixes: 309795f4bec2 ("l2tp: Add netlink control API for L2TP")
Fixes: d9e31d17ceba ("l2tp: Add L2TP ethernet pseudowire support")
Signed-off-by: Guillaume Nault 
Signed-off-by: David S. Miller

l2tp: cast l2tp traffic counter to unsigned

2017-06-10T20:14:27+00:00

This fixes a counter problem on 32bit systems:
When the rx_bytes counter reached 2 GiB, it jumpd to (2^64 Bytes - 2GiB) Bytes.

rtnl_link_stats64 has __u64 type and atomic_long_read returns
atomic_long_t which is signed. Due to the conversation
we get an incorrect value on 32bit systems if the MSB of
the atomic_long_t value is set.

CC: Tom Parkin 
Fixes: 7b7c0719cd7a ("l2tp: avoid deadlock in l2tp stats update")
Signed-off-by: Dominik Heidler 
Signed-off-by: David S. Miller

net: Fix inconsistent teardown and release of private netdev state.

2017-06-07T19:53:24+00:00

Network devices can allocate reasources and private memory using
netdev_ops->ndo_init().  However, the release of these resources
can occur in one of two different places.

Either netdev_ops->ndo_uninit() or netdev->destructor().

The decision of which operation frees the resources depends upon
whether it is necessary for all netdev refs to be released before it
is safe to perform the freeing.

netdev_ops->ndo_uninit() presumably can occur right after the
NETDEV_UNREGISTER notifier completes and the unicast and multicast
address lists are flushed.

netdev->destructor(), on the other hand, does not run until the
netdev references all go away.

Further complicating the situation is that netdev->destructor()
almost universally does also a free_netdev().

This creates a problem for the logic in register_netdevice().
Because all callers of register_netdevice() manage the freeing
of the netdev, and invoke free_netdev(dev) if register_netdevice()
fails.

If netdev_ops->ndo_init() succeeds, but something else fails inside
of register_netdevice(), it does call ndo_ops->ndo_uninit().  But
it is not able to invoke netdev->destructor().

This is because netdev->destructor() will do a free_netdev() and
then the caller of register_netdevice() will do the same.

However, this means that the resources that would normally be released
by netdev->destructor() will not be.

Over the years drivers have added local hacks to deal with this, by
invoking their destructor parts by hand when register_netdevice()
fails.

Many drivers do not try to deal with this, and instead we have leaks.

Let's close this hole by formalizing the distinction between what
private things need to be freed up by netdev->destructor() and whether
the driver needs unregister_netdevice() to perform the free_netdev().

netdev->priv_destructor() performs all actions to free up the private
resources that used to be freed by netdev->destructor(), except for
free_netdev().

netdev->needs_free_netdev is a boolean that indicates whether
free_netdev() should be done at the end of unregister_netdevice().

Now, register_netdevice() can sanely release all resources after
ndo_ops->ndo_init() succeeds, by invoking both ndo_ops->ndo_uninit()
and netdev->priv_destructor().

And at the end of unregister_netdevice(), we invoke
netdev->priv_destructor() and optionally call free_netdev().

Signed-off-by: David S. Miller

l2tp: remove useless device duplication test in l2tp_eth_create()

2017-04-27T20:32:13+00:00

There's no need to verify that cfg->ifname is unique at this point.
register_netdev() will return -EEXIST if asked to create a device with
a name that's alrealy in use.

Signed-off-by: Guillaume Nault 
Signed-off-by: David S. Miller

l2tp: define "l2tpeth" device type

2017-04-25T15:41:56+00:00

Export type of l2tpeth interfaces to userspace
(/sys/class/net//uevent).

Signed-off-by: Guillaume Nault 
Acked-by: James Chapman 
Signed-off-by: David S. Miller