mac80211: restrict assoc request VHT capabilities

In interoperability testing some APs showed bad behaviour
if some of the VHT capabilities of the station are better
than their own. Restrict the assoc request parameters
 - beamformee capabable,
 - RX STBC and
 - RX MCS set
to the subset that the AP can support.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index c084c1503c0408ca665d39cde3bd7d0ed436f50e..7182907e282a2290488fa05f8ff552d31b3022ad 100644 (file)
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -405,6 +405,8 @@ struct ieee80211_mgd_assoc_data {
 
        u8 ap_ht_param;
 
+       struct ieee80211_vht_cap ap_vht_cap;
+
        size_t ie_len;
        u8 ie[];
 };

diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index 7d253a02217333d1c8d29e5ca35e524ae9124d18..6ffbf701de95a72bb15b5dba18b6a790038efc39 100644 (file)
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -341,11 +341,13 @@ static void ieee80211_add_ht_ie(struct ieee80211_sub_if_data *sdata,
 
 static void ieee80211_add_vht_ie(struct ieee80211_sub_if_data *sdata,
                                 struct sk_buff *skb,
-                                struct ieee80211_supported_band *sband)
+                                struct ieee80211_supported_band *sband,
+                                struct ieee80211_vht_cap *ap_vht_cap)
 {
        u8 *pos;
        u32 cap;
        struct ieee80211_sta_vht_cap vht_cap;
+       int i;
 
        BUILD_BUG_ON(sizeof(vht_cap) != sizeof(sband->vht_cap));
 
@@ -364,6 +366,42 @@ static void ieee80211_add_vht_ie(struct ieee80211_sub_if_data *sdata,
                cap &= ~IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160MHZ;
        }
 
+       /*
+        * Some APs apparently get confused if our capabilities are better
+        * than theirs, so restrict what we advertise in the assoc request.
+        */
+       if (!(ap_vht_cap->vht_cap_info &
+                       cpu_to_le32(IEEE80211_VHT_CAP_SU_BEAMFORMER_CAPABLE)))
+               cap &= ~IEEE80211_VHT_CAP_SU_BEAMFORMEE_CAPABLE;
+
+       if (!(ap_vht_cap->vht_cap_info &
+                       cpu_to_le32(IEEE80211_VHT_CAP_TXSTBC)))
+               cap &= ~(IEEE80211_VHT_CAP_RXSTBC_1 |
+                        IEEE80211_VHT_CAP_RXSTBC_3 |
+                        IEEE80211_VHT_CAP_RXSTBC_4);
+
+       for (i = 0; i < 8; i++) {
+               int shift = i * 2;
+               u16 mask = IEEE80211_VHT_MCS_NOT_SUPPORTED << shift;
+               u16 ap_mcs, our_mcs;
+
+               ap_mcs = (le16_to_cpu(ap_vht_cap->supp_mcs.tx_mcs_map) &
+                                                               mask) >> shift;
+               our_mcs = (le16_to_cpu(vht_cap.vht_mcs.rx_mcs_map) &
+                                                               mask) >> shift;
+
+               switch (ap_mcs) {
+               default:
+                       if (our_mcs <= ap_mcs)
+                               break;
+                       /* fall through */
+               case IEEE80211_VHT_MCS_NOT_SUPPORTED:
+                       vht_cap.vht_mcs.rx_mcs_map &= cpu_to_le16(~mask);
+                       vht_cap.vht_mcs.rx_mcs_map |=
+                               cpu_to_le16(ap_mcs << shift);
+               }
+       }
+
        /* reserve and fill IE */
        pos = skb_put(skb, sizeof(struct ieee80211_vht_cap) + 2);
        ieee80211_ie_build_vht_cap(pos, &vht_cap, cap);
@@ -562,7 +600,8 @@ static void ieee80211_send_assoc(struct ieee80211_sub_if_data *sdata)
                                    sband, chan, sdata->smps_mode);
 
        if (!(ifmgd->flags & IEEE80211_STA_DISABLE_VHT))
-               ieee80211_add_vht_ie(sdata, skb, sband);
+               ieee80211_add_vht_ie(sdata, skb, sband,
+                                    &assoc_data->ap_vht_cap);
 
        /* if present, add any custom non-vendor IEs that go after HT */
        if (assoc_data->ie_len && assoc_data->ie) {
@@ -3753,7 +3792,7 @@ int ieee80211_mgd_assoc(struct ieee80211_sub_if_data *sdata,
        struct ieee80211_bss *bss = (void *)req->bss->priv;
        struct ieee80211_mgd_assoc_data *assoc_data;
        struct ieee80211_supported_band *sband;
-       const u8 *ssidie, *ht_ie;
+       const u8 *ssidie, *ht_ie, *vht_ie;
        int i, err;
 
        assoc_data = kzalloc(sizeof(*assoc_data) + req->ie_len, GFP_KERNEL);
@@ -3872,6 +3911,12 @@ int ieee80211_mgd_assoc(struct ieee80211_sub_if_data *sdata,
                        ((struct ieee80211_ht_operation *)(ht_ie + 2))->ht_param;
        else
                ifmgd->flags |= IEEE80211_STA_DISABLE_HT;
+       vht_ie = ieee80211_bss_get_ie(req->bss, WLAN_EID_VHT_CAPABILITY);
+       if (vht_ie && vht_ie[1] >= sizeof(struct ieee80211_vht_cap))
+               memcpy(&assoc_data->ap_vht_cap, vht_ie + 2,
+                      sizeof(struct ieee80211_vht_cap));
+       else
+               ifmgd->flags |= IEEE80211_STA_DISABLE_VHT;
        rcu_read_unlock();
 
        if (bss->wmm_used && bss->uapsd_supported &&