mac80211: handle deauthentication/disassociation from TDLS peer [Linux 5.2]

mac80211: handle deauthentication/disassociation from TDLS peer [Linux 5.2]

This Linux kernel change "mac80211: handle deauthentication/disassociation from TDLS peer" is included in the Linux 5.2 release. This change is authored by Yu Wang <yyuwang [at] codeaurora.org> on Fri May 10 17:04:52 2019 +0800. The commit for this change in Linux stable tree is 79c92ca (patch).

mac80211: handle deauthentication/disassociation from TDLS peer

When receiving a deauthentication/disassociation frame from a TDLS
peer, a station should not disconnect the current AP, but only
disable the current TDLS link if it's enabled.

Without this change, a TDLS issue can be reproduced by following the
steps as below:

1. STA-1 and STA-2 are connected to AP, bidirection traffic is running
   between STA-1 and STA-2.
2. Set up TDLS link between STA-1 and STA-2, stay for a while, then
   teardown TDLS link.
3. Repeat step #2 and monitor the connection between STA and AP.

During the test, one STA may send a deauthentication/disassociation
frame to another, after TDLS teardown, with reason code 6/7, which
means: Class 2/3 frame received from nonassociated STA.

On receive this frame, the receiver STA will disconnect the current
AP and then reconnect. It's not a expected behavior, purpose of this
frame should be disabling the TDLS link, not the link with AP.

Cc: [email protected]
Signed-off-by: Yu Wang <[email protected]>
Signed-off-by: Johannes Berg <[email protected]>

There are 38 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 net/mac80211/ieee80211_i.h |  3 +++
 net/mac80211/mlme.c        | 12 +++++++++++-
 net/mac80211/tdls.c        | 23 +++++++++++++++++++++++
 3 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 073a823..a8af4aa 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -2225,6 +2225,9 @@ void ieee80211_tdls_cancel_channel_switch(struct wiphy *wiphy,
                      const u8 *addr);
 void ieee80211_teardown_tdls_peers(struct ieee80211_sub_if_data *sdata);
 void ieee80211_tdls_chsw_work(struct work_struct *wk);
+void ieee80211_tdls_handle_disconnect(struct ieee80211_sub_if_data *sdata,
+                     const u8 *peer, u16 reason);
+const char *ieee80211_get_reason_code_string(u16 reason_code);

 extern const struct ethtool_ops ieee80211_ethtool_ops;

diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index b7a9fe3d..383b0df 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -2963,7 +2963,7 @@ static void ieee80211_rx_mgmt_auth(struct ieee80211_sub_if_data *sdata,
 #define case_WLAN(type) \
    case WLAN_REASON_##type: return #type

-static const char *ieee80211_get_reason_code_string(u16 reason_code)
+const char *ieee80211_get_reason_code_string(u16 reason_code)
 {
    switch (reason_code) {
    case_WLAN(UNSPECIFIED);
@@ -3028,6 +3028,11 @@ static void ieee80211_rx_mgmt_deauth(struct ieee80211_sub_if_data *sdata,
    if (len < 24 + 2)
        return;

+   if (!ether_addr_equal(mgmt->bssid, mgmt->sa)) {
+       ieee80211_tdls_handle_disconnect(sdata, mgmt->sa, reason_code);
+       return;
+   }
+
    if (ifmgd->associated &&
        ether_addr_equal(mgmt->bssid, ifmgd->associated->bssid)) {
        const u8 *bssid = ifmgd->associated->bssid;
@@ -3077,6 +3082,11 @@ static void ieee80211_rx_mgmt_disassoc(struct ieee80211_sub_if_data *sdata,

    reason_code = le16_to_cpu(mgmt->u.disassoc.reason_code);

+   if (!ether_addr_equal(mgmt->bssid, mgmt->sa)) {
+       ieee80211_tdls_handle_disconnect(sdata, mgmt->sa, reason_code);
+       return;
+   }
+
    sdata_info(sdata, "disassociated from %pM (Reason: %u=%s)\n",
           mgmt->sa, reason_code,
           ieee80211_get_reason_code_string(reason_code));
diff --git a/net/mac80211/tdls.c b/net/mac80211/tdls.c
index 24c37f9..ba8fe48 100644
--- a/net/mac80211/tdls.c
+++ b/net/mac80211/tdls.c
@@ -1994,3 +1994,26 @@ void ieee80211_tdls_chsw_work(struct work_struct *wk)
    }
    rtnl_unlock();
 }
+
+void ieee80211_tdls_handle_disconnect(struct ieee80211_sub_if_data *sdata,
+                     const u8 *peer, u16 reason)
+{
+   struct ieee80211_sta *sta;
+
+   rcu_read_lock();
+   sta = ieee80211_find_sta(&sdata->vif, peer);
+   if (!sta || !sta->tdls) {
+       rcu_read_unlock();
+       return;
+   }
+   rcu_read_unlock();
+
+   tdls_dbg(sdata, "disconnected from TDLS peer %pM (Reason: %u=%s)\n",
+        peer, reason,
+        ieee80211_get_reason_code_string(reason));
+
+   ieee80211_tdls_oper_request(&sdata->vif, peer,
+                   NL80211_TDLS_TEARDOWN,
+                   WLAN_REASON_TDLS_TEARDOWN_UNREACHABLE,
+                   GFP_ATOMIC);
+}

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