The 802.15.4-2011 standard states that for each key, a list of devices
that use this key shall be kept. Previous patches have only considered
two options:

 * a device "uses" (or may use) all keys, rendering the list useless
 * a device is restricted to a certain set of keys

Another option would be that a device *may* use all keys, but need not
do so, and we are interested in the actual set of keys the device uses.
Recording keys used by any given device may have a noticable performance
impact and might not be needed as often. The common case, in which a
device will not switch keys too often, should still perform well.
Signed-off-by: NPhoebe Buckheister <phoebe.buckheister@itwm.fraunhofer.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NPhoebe Buckheister <phoebe.buckheister@itwm.fraunhofer.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NPhoebe Buckheister <phoebe.buckheister@itwm.fraunhofer.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch adds containers and mutators for the major ieee802154_llsec
structures to mac802154. Most of the (rather simple) ieee802154_llsec
structs are wrapped only to provide an rcu_head for orderly disposal,
but some structs - llsec keys notably - require more complex
bookkeeping.

Since each llsec key may be referenced by a number of llsec key table
entries (with differing key ids, but the same actual key), we want to
save memory and not allocate crypto transforms for each entry in the
table. Thus, the mac802154 llsec key is reference-counted instead.
Further, each key will have four associated crypto transforms - three
CCM transforms for the authsizes 4/8/16 and one CTR transform for
unauthenticated encryption. If we had a CCM* transform that allowed
authsize 0, and authsize as part of requests instead of transforms, this
would not be necessary.
Signed-off-by: NPhoebe Buckheister <phoebe.buckheister@itwm.fraunhofer.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>