nl80211: Add notification for dropped Deauth/Disassoc

Add a new notification to indicate that a received, unprotected
Deauthentication or Disassociation frame was dropped due to
management frame protection being in use. This notification is
needed to allow user space (e.g., wpa_supplicant) to implement
SA Query procedure to recover from association state mismatch
between an AP and STA.

This is needed to avoid getting stuck in non-working state when MFP
(IEEE 802.11w) is used and a protected Deauthentication or
Disassociation frame is dropped for any reason. After that, the
station would silently discard any unprotected Deauthentication or
Disassociation frame that could be indicating that the AP does not
have association for the STA (when the Reason Code would be 6 or 7).
IEEE Std 802.11w-2009, 11.13 describes this recovery mechanism.

Signed-off-by: Jouni Malinen <j@w1.fi>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 20 insertions, 2 deletions

diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 052789ef4745..4573ce1e1d15 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -1540,12 +1540,30 @@ ieee80211_drop_unencrypted_mgmt(struct ieee80211_rx_data *rx)
         if (rx->sta && test_sta_flags(rx->sta, WLAN_STA_MFP)) {
                 if (unlikely(!ieee80211_has_protected(fc) &&
                              ieee80211_is_unicast_robust_mgmt_frame(rx->skb) &&
-                             rx->key))
+                             rx->key)) {
+                        if (ieee80211_is_deauth(fc))
+                                cfg80211_send_unprot_deauth(rx->sdata->dev,
+                                                            rx->skb->data,
+                                                            rx->skb->len);
+                        else if (ieee80211_is_disassoc(fc))
+                                cfg80211_send_unprot_disassoc(rx->sdata->dev,
+                                                              rx->skb->data,
+                                                              rx->skb->len);
                         return -EACCES;
+                }
                 /* BIP does not use Protected field, so need to check MMIE */
                 if (unlikely(ieee80211_is_multicast_robust_mgmt_frame(rx->skb) &&
-                             ieee80211_get_mmie_keyidx(rx->skb) < 0))
+                             ieee80211_get_mmie_keyidx(rx->skb) < 0)) {
+                        if (ieee80211_is_deauth(fc))
+                                cfg80211_send_unprot_deauth(rx->sdata->dev,
+                                                            rx->skb->data,
+                                                            rx->skb->len);
+                        else if (ieee80211_is_disassoc(fc))
+                                cfg80211_send_unprot_disassoc(rx->sdata->dev,
+                                                              rx->skb->data,
+                                                              rx->skb->len);
                         return -EACCES;
+                }
                 /*
                  * When using MFP, Action frames are not allowed prior to
                  * having configured keys.