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>

4 files changed, 64 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.
diff --git a/net/wireless/mlme.c b/net/wireless/mlme.c
index d7680f2a4c5b..aa5df8865ff7 100644
--- a/net/wireless/mlme.c
+++ b/net/wireless/mlme.c
@@ -263,6 +263,28 @@ void cfg80211_send_disassoc(struct net_device *dev, const u8 *buf, size_t len)
 }
 EXPORT_SYMBOL(cfg80211_send_disassoc);
 
+void cfg80211_send_unprot_deauth(struct net_device *dev, const u8 *buf,
+                                 size_t len)
+{
+        struct wireless_dev *wdev = dev->ieee80211_ptr;
+        struct wiphy *wiphy = wdev->wiphy;
+        struct cfg80211_registered_device *rdev = wiphy_to_dev(wiphy);
+
+        nl80211_send_unprot_deauth(rdev, dev, buf, len, GFP_ATOMIC);
+}
+EXPORT_SYMBOL(cfg80211_send_unprot_deauth);
+
+void cfg80211_send_unprot_disassoc(struct net_device *dev, const u8 *buf,
+                                   size_t len)
+{
+        struct wireless_dev *wdev = dev->ieee80211_ptr;
+        struct wiphy *wiphy = wdev->wiphy;
+        struct cfg80211_registered_device *rdev = wiphy_to_dev(wiphy);
+
+        nl80211_send_unprot_disassoc(rdev, dev, buf, len, GFP_ATOMIC);
+}
+EXPORT_SYMBOL(cfg80211_send_unprot_disassoc);
+
 static void __cfg80211_auth_remove(struct wireless_dev *wdev, const u8 *addr)
 {
         int i;
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 594a6ac8b9d2..aefce54d47e2 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -5473,6 +5473,22 @@ void nl80211_send_disassoc(struct cfg80211_registered_device *rdev,
                                 NL80211_CMD_DISASSOCIATE, gfp);
 }
 
+void nl80211_send_unprot_deauth(struct cfg80211_registered_device *rdev,
+                                struct net_device *netdev, const u8 *buf,
+                                size_t len, gfp_t gfp)
+{
+        nl80211_send_mlme_event(rdev, netdev, buf, len,
+                                NL80211_CMD_UNPROT_DEAUTHENTICATE, gfp);
+}
+
+void nl80211_send_unprot_disassoc(struct cfg80211_registered_device *rdev,
+                                  struct net_device *netdev, const u8 *buf,
+                                  size_t len, gfp_t gfp)
+{
+        nl80211_send_mlme_event(rdev, netdev, buf, len,
+                                NL80211_CMD_UNPROT_DISASSOCIATE, gfp);
+}
+
 static void nl80211_send_mlme_timeout(struct cfg80211_registered_device *rdev,
                                       struct net_device *netdev, int cmd,
                                       const u8 *addr, gfp_t gfp)
diff --git a/net/wireless/nl80211.h b/net/wireless/nl80211.h
index 16c2f7190768..e3f7fa886966 100644
--- a/net/wireless/nl80211.h
+++ b/net/wireless/nl80211.h
@@ -25,6 +25,12 @@ void nl80211_send_deauth(struct cfg80211_registered_device *rdev,
 void nl80211_send_disassoc(struct cfg80211_registered_device *rdev,
                            struct net_device *netdev,
                            const u8 *buf, size_t len, gfp_t gfp);
+void nl80211_send_unprot_deauth(struct cfg80211_registered_device *rdev,
+                                struct net_device *netdev,
+                                const u8 *buf, size_t len, gfp_t gfp);
+void nl80211_send_unprot_disassoc(struct cfg80211_registered_device *rdev,
+                                  struct net_device *netdev,
+                                  const u8 *buf, size_t len, gfp_t gfp);
 void nl80211_send_auth_timeout(struct cfg80211_registered_device *rdev,
                                struct net_device *netdev,
                                const u8 *addr, gfp_t gfp);