mac80211: drop data frames without key on encrypted links

commit a0761a301746ec2d92d7fcb82af69c0a6a4339aa upstream.

If we know that we have an encrypted link (based on having had
a key configured for TX in the past) then drop all data frames
in the key selection handler if there's no key anymore.

This fixes an issue with mac80211 internal TXQs - there we can
buffer frames for an encrypted link, but then if the key is no
longer there when they're dequeued, the frames are sent without
encryption. This happens if a station is disconnected while the
frames are still on the TXQ.

Detecting that a link should be encrypted based on a first key
having been configured for TX is fine as there are no use cases
for a connection going from with encryption to no encryption.
With extended key IDs, however, there is a case of having a key
configured for only decryption, so we can't just trigger this
behaviour on a key being configured.

Cc: stable@vger.kernel.org
Reported-by: Jouni Malinen <j@w1.fi>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20200326150855.6865c7f28a14.I9fb1d911b064262d33e33dfba730cdeef83926ca@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
[pali: Backported to 4.19 and older versions]
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/mac80211/debugfs_sta.c b/net/mac80211/debugfs_sta.c
index 4105081dc1df01ba14a11c855c1c65e163b7db5c..6f390c2e4c8ea5cf87795ab007aafb42cd255ffb 100644 (file)
--- a/net/mac80211/debugfs_sta.c
+++ b/net/mac80211/debugfs_sta.c
@@ -80,6 +80,7 @@ static const char * const sta_flag_names[] = {
        FLAG(MPSP_OWNER),
        FLAG(MPSP_RECIPIENT),
        FLAG(PS_DELIVER),
+       FLAG(USES_ENCRYPTION),
 #undef FLAG
 };
 

diff --git a/net/mac80211/key.c b/net/mac80211/key.c
index 6775d6cb7d3d4d0f31de0f78a92549d1d86dd3ce..7fc55177db84738ebfc18b666cf0e58f5b1d17b9 100644 (file)
--- a/net/mac80211/key.c
+++ b/net/mac80211/key.c
@@ -341,6 +341,7 @@ static void ieee80211_key_replace(struct ieee80211_sub_if_data *sdata,
        if (sta) {
                if (pairwise) {
                        rcu_assign_pointer(sta->ptk[idx], new);
+                       set_sta_flag(sta, WLAN_STA_USES_ENCRYPTION);
                        sta->ptk_idx = idx;
                        ieee80211_check_fast_xmit(sta);
                } else {

diff --git a/net/mac80211/sta_info.h b/net/mac80211/sta_info.h
index c33bc5fc0f2d892f6b2e7f11ac9ec1f4923b9cd3..75d982ff7f3d0214d5da9bca3ea046628bceaaaf 100644 (file)
--- a/net/mac80211/sta_info.h
+++ b/net/mac80211/sta_info.h
@@ -102,6 +102,7 @@ enum ieee80211_sta_info_flags {
        WLAN_STA_MPSP_OWNER,
        WLAN_STA_MPSP_RECIPIENT,
        WLAN_STA_PS_DELIVER,
+       WLAN_STA_USES_ENCRYPTION,
 
        NUM_WLAN_STA_FLAGS,
 };

diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 98d048630ad2fbeb80891b013a977dd8eae38d2d..3530d1a5fc98e1e672aa83cde3ad3797873231fc 100644 (file)
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -593,10 +593,13 @@ ieee80211_tx_h_select_key(struct ieee80211_tx_data *tx)
        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(tx->skb);
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)tx->skb->data;
 
-       if (unlikely(info->flags & IEEE80211_TX_INTFL_DONT_ENCRYPT))
+       if (unlikely(info->flags & IEEE80211_TX_INTFL_DONT_ENCRYPT)) {
                tx->key = NULL;
-       else if (tx->sta &&
-                (key = rcu_dereference(tx->sta->ptk[tx->sta->ptk_idx])))
+               return TX_CONTINUE;
+       }
+
+       if (tx->sta &&
+           (key = rcu_dereference(tx->sta->ptk[tx->sta->ptk_idx])))
                tx->key = key;
        else if (ieee80211_is_group_privacy_action(tx->skb) &&
                (key = rcu_dereference(tx->sdata->default_multicast_key)))
@@ -657,6 +660,9 @@ ieee80211_tx_h_select_key(struct ieee80211_tx_data *tx)
                if (!skip_hw && tx->key &&
                    tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)
                        info->control.hw_key = &tx->key->conf;
+       } else if (!ieee80211_is_mgmt(hdr->frame_control) && tx->sta &&
+                  test_sta_flag(tx->sta, WLAN_STA_USES_ENCRYPTION)) {
+               return TX_DROP;
        }
 
        return TX_CONTINUE;