[MAC80211]: improve key selection comment

When I changed the code there I forgot to mention what happens
with multicast frames in a regular BSS and keep wondering myself
if the code is correct. Add appropriate comments.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Acked-by: Michael Wu <flamingice@sourmilk.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 969be3a..75a1e20 100644 (file)
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -327,8 +327,15 @@ ieee80211_rx_h_load_key(struct ieee80211_txrx_data *rx)
         * frames can also use key indizes like GTKs. Hence, if we don't
         * have a PTK/STK we check the key index for a WEP key.
         *
+        * Note that in a regular BSS, multicast frames are sent by the
+        * AP only, associated stations unicast the frame to the AP first
+        * which then multicasts it on their behalf.
+        *
         * There is also a slight problem in IBSS mode: GTKs are negotiated
         * with each station, that is something we don't currently handle.
+        * The spec seems to expect that one negotiates the same key with
+        * every station but there's no such requirement; VLANs could be
+        * possible.
         */
 
        if (!(rx->fc & IEEE80211_FCTL_PROTECTED))