ieee802154, mac802154: implement devkey record option

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

1 files changed, 38 insertions, 0 deletions

diff --git a/net/mac802154/llsec.c b/net/mac802154/llsec.c
index 392653b1b5a3..a83674edaafd 100644
--- a/net/mac802154/llsec.c
+++ b/net/mac802154/llsec.c
@@ -921,6 +921,37 @@ llsec_do_decrypt(struct sk_buff *skb, const struct mac802154_llsec *sec,
 }
 
 static int
+llsec_update_devkey_record(struct mac802154_llsec_device *dev,
+                           const struct ieee802154_llsec_key_id *in_key)
+{
+        struct mac802154_llsec_device_key *devkey;
+
+        devkey = llsec_devkey_find(dev, in_key);
+
+        if (!devkey) {
+                struct mac802154_llsec_device_key *next;
+
+                next = kzalloc(sizeof(*devkey), GFP_ATOMIC);
+                if (!next)
+                        return -ENOMEM;
+
+                next->devkey.key_id = *in_key;
+
+                spin_lock_bh(&dev->lock);
+
+                devkey = llsec_devkey_find(dev, in_key);
+                if (!devkey)
+                        list_add_rcu(&next->devkey.list, &dev->dev.keys);
+                else
+                        kfree(next);
+
+                spin_unlock_bh(&dev->lock);
+        }
+
+        return 0;
+}
+
+static int
 llsec_update_devkey_info(struct mac802154_llsec_device *dev,
                          const struct ieee802154_llsec_key_id *in_key,
                          u32 frame_counter)
@@ -933,6 +964,13 @@ llsec_update_devkey_info(struct mac802154_llsec_device *dev,
                         return -ENOENT;
         }
 
+        if (dev->dev.key_mode == IEEE802154_LLSEC_DEVKEY_RECORD) {
+                int rc = llsec_update_devkey_record(dev, in_key);
+
+                if (rc < 0)
+                        return rc;
+        }
+
         spin_lock_bh(&dev->lock);
 
         if ((!devkey && frame_counter < dev->dev.frame_counter) ||