netif_rx() must be called under a strict contract.

At device dismantle phase, core networking clears IFF_UP
and flush_all_backlogs() is called after rcu grace period
to make sure no incoming packet might be in a cpu backlog
and still referencing the device.

Most drivers call netif_rx() from their interrupt handler,
and since the interrupts are disabled at device dismantle,
netif_rx() does not have to check dev->flags & IFF_UP

Virtual drivers do not have this guarantee, and must
therefore make the check themselves.

Otherwise we risk use-after-free and/or crashes.

Note this patch also fixes a small issue that came
with commit ce6502a8f957 ("vxlan: fix a use after free
in vxlan_encap_bypass"), since the dev->stats.rx_dropped
change was done on the wrong device.

Fixes: d342894c5d2f ("vxlan: virtual extensible lan")
Fixes: ce6502a8f957 ("vxlan: fix a use after free in vxlan_encap_bypass")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Petr Machata <petrm@mellanox.com>
Cc: Ido Schimmel <idosch@mellanox.com>
Cc: Roopa Prabhu <roopa@cumulusnetworks.com>
Cc: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

When resolving the conflict wrt. the vxlan_fdb_update call
in vxlan_changelink() I made the last argument false instead
of true.

Fix this.

Signed-off-by: David S. Miller <davem@davemloft.net>

Lots of conflicts, by happily all cases of overlapping
changes, parallel adds, things of that nature.

Thanks to Stephen Rothwell, Saeed Mahameed, and others
for their guidance in these resolutions.

Signed-off-by: David S. Miller <davem@davemloft.net>

Default remotes are stored as FDB entries with an Ethernet address of
00:00:00:00:00:00. When a request is made to change a remote address of
a VXLAN device, vxlan_changelink() first deletes the existing default
remote, and then creates a new FDB entry.

This works well as long as the list of default remotes matches exactly
the configuration of a VXLAN remote address. Thus when the VXLAN device
has a remote of X, there should be exactly one default remote FDB entry
X. If the VXLAN device has no remote address, there should be no such
entry.

Besides using "ip link set", it is possible to manipulate the list of
default remotes by using the "bridge fdb". It is therefore easy to break
the above condition. Under such circumstances, the __vxlan_fdb_delete()
call doesn't delete the FDB entry itself, but just one remote. The
following vxlan_fdb_create() then creates a new FDB entry, leading to a
situation where two entries exist for the address 00:00:00:00:00:00,
each with a different subset of default remotes.

An even more obvious breakage rooted in the same cause can be observed
when a remote address is configured for a VXLAN device that did not have
one before. In that case vxlan_changelink() doesn't remove any remote,
and just creates a new FDB entry for the new address:

$ ip link add name vx up type vxlan id 2000 dstport 4789
$ bridge fdb ap dev vx 00:00:00:00:00:00 dst 192.0.2.20 self permanent
$ bridge fdb ap dev vx 00:00:00:00:00:00 dst 192.0.2.30 self permanent
$ ip link set dev vx type vxlan remote 192.0.2.30
$ bridge fdb sh dev vx | grep 00:00:00:00:00:00
00:00:00:00:00:00 dst 192.0.2.30 self permanent <- new entry, 1 rdst
00:00:00:00:00:00 dst 192.0.2.20 self permanent <- orig. entry, 2 rdsts
00:00:00:00:00:00 dst 192.0.2.30 self permanent

To fix this, instead of calling vxlan_fdb_create() directly, defer to
vxlan_fdb_update(). That has logic to handle the duplicates properly.
Additionally, it also handles notifications, so drop that call from
changelink as well.

Fixes: 0241b836732f ("vxlan: fix default fdb entry netlink notify ordering during netdev create")
Signed-off-by: Petr Machata <petrm@mellanox.com>
Acked-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

When a failure occurs in rtnl_configure_link(), the current code
calls unregister_netdevice() to roll back the earlier call to
register_netdevice(), and jumps to errout, which calls
vxlan_fdb_destroy().

However unregister_netdevice() calls transitively ndo_uninit, which is
vxlan_uninit(), and that already takes care of deleting the default FDB
entry by calling vxlan_fdb_delete_default(). Since the entry added
earlier in __vxlan_dev_create() is exactly the default entry, the
cleanup code in the errout block always leads to double free and thus a
panic.

Besides, since vxlan_fdb_delete_default() always destroys the FDB entry
with notification enabled, the deletion of the default entry is notified
even before the addition was notified.

Instead, move the unregister_netdevice() call after the manual destroy,
which solves both problems.

Fixes: 0241b836732f ("vxlan: fix default fdb entry netlink notify ordering during netdev create")
Signed-off-by: Petr Machata <petrm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

When rdst of an offloaded FDB entry is replaced, it certainly isn't
offloaded anymore. Drivers are notified about such replacements, and can
re-mark the entry as offloaded again if they so wish. However until a
driver does so explicitly, assume a replaced FDB entry is not offloaded.

Note that replaces coming via vxlan_fdb_external_learn_add() are always
immediately followed by an explicit offload marking.

Fixes: 0efe11733356 ("vxlan: Support marking RDSTs as offloaded")
Signed-off-by: Petr Machata <petrm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

This patch implements ndo_fdb_get for a vxlan device.

Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Reviewed-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

In order to pass extack to the drivers that need it, add an extack field
to struct switchdev_notifier_info, and an extack argument to the
function call_switchdev_blocking_notifiers(). Also add a helper function
switchdev_notifier_info_to_extack().

Signed-off-by: Petr Machata <petrm@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Acked-by: Ivan Vecera <ivecera@redhat.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

When a driver unoffloads all FDB entries en bloc, it's inefficient to
send the switchdev notification one by one. Add a helper that walks the
FDB table, unsetting the offload flag on RDST with a given VNI.

Signed-off-by: Petr Machata <petrm@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

When a VXLAN device becomes relevant to a driver (such as when it is
attached to an offloaded bridge), the driver will generally need to walk
the existing FDB entries and offload them.

Add a function vxlan_fdb_replay() to call a given notifier block for
each FDB entry with a given VNI.

Signed-off-by: Petr Machata <petrm@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>