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[ Upstream commit dea6e19f4ef746aa18b4c33d1a7fed54356796ed ]
The commit 9a393b5d5988 ("tap: tap as an independent module") created a
separate tap module that implements tap functionality and exports
interfaces that will be used by macvtap and ipvtap modules to create
create respective tap devices.
However, that patch introduced a regression wherein the modules macvtap
and ipvtap can be removed (through modprobe -r) while there are
applications using the respective /dev/tapX devices. These applications
cause kernel to hold reference to /dev/tapX through 'struct cdev
macvtap_cdev' and 'struct cdev ipvtap_dev' defined in macvtap and ipvtap
modules respectively. So, when the application is later closed the
kernel panics because we are referencing KVA that is present in the
unloaded modules.
----------8<------- Example ----------8<----------
$ sudo ip li add name mv0 link enp7s0 type macvtap
$ sudo ip li show mv0 |grep mv0| awk -e '{print $1 $2}'
14:mv0@enp7s0:
$ cat /dev/tap14 &
$ lsmod |egrep -i 'tap|vlan'
macvtap 16384 0
macvlan 24576 1 macvtap
tap 24576 3 macvtap
$ sudo modprobe -r macvtap
$ fg
cat /dev/tap14
^C
<...system panics...>
BUG: unable to handle kernel paging request at ffffffffa038c500
IP: cdev_put+0xf/0x30
----------8<-----------------8<----------
The fix is to set cdev.owner to the module that creates the tap device
(either macvtap or ipvtap). With this set, the operations (in
fs/char_dev.c) on char device holds and releases the module through
cdev_get() and cdev_put() and will not allow the module to unload
prematurely.
Fixes: 9a393b5d5988ea4e (tap: tap as an independent module)
Signed-off-by: Girish Moodalbail <girish.moodalbail@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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This patch exports skb_array through tap_get_skb_array(). Caller can
then manipulate skb array directly.
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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This patch makes tap a separate module for other types of virtual interfaces, for example,
ipvlan to use.
Signed-off-by: Sainath Grandhi <sainath.grandhi@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Extending tap APIs get/free_minor and create/destroy_cdev to handle more than one
type of virtual interface.
Signed-off-by: Sainath Grandhi <sainath.grandhi@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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macvlan object is re-structured to hold tap related elements in a separate
entity, tap_dev. Upon NETDEV_REGISTER device_event, tap_dev is registered with
idr and fetched again on tap_open. Few of the tap functions are modified to
accepted tap_dev as argument. tap_dev object includes callbacks to be used by
underlying virtual interface to take care of tx and rx accounting.
Signed-off-by: Sainath Grandhi <sainath.grandhi@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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This patch provides tap device create/destroy APIs in tap.c.
Signed-off-by: Sainath Grandhi <sainath.grandhi@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Renaming tap related APIs, data structures and macros in tap.c from macvtap_.* to tap_.*
Signed-off-by: Sainath Grandhi <sainath.grandhi@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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