mac80211: handle protection mode, RIFS and ADDBA for HT IBSS

* Follow 802.11n-2009 9.13.3.1 for protection mode and ADDBA
* Send ADDBA only to HT STAs - implement 11.5.1.1 partially

Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Signed-off-by: Mathias Kretschmer <mathias.kretschmer@fokus.fraunhofer.de>
Reviewed-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

3 files changed, 44 insertions, 0 deletions

diff --git a/net/mac80211/agg-tx.c b/net/mac80211/agg-tx.c
index 2c2e9519a2e..9bfe28c9ab5 100644
--- a/net/mac80211/agg-tx.c
+++ b/net/mac80211/agg-tx.c
@@ -430,6 +430,27 @@ int ieee80211_start_tx_ba_session(struct ieee80211_sta *pubsta, u16 tid,
                 return -EINVAL;
         }
 
+        /*
+         * 802.11n-2009 11.5.1.1: If the initiating STA is an HT STA, is a
+         * member of an IBSS, and has no other existing Block Ack agreement
+         * with the recipient STA, then the initiating STA shall transmit a
+         * Probe Request frame to the recipient STA and shall not transmit an
+         * ADDBA Request frame unless it receives a Probe Response frame
+         * from the recipient within dot11ADDBAFailureTimeout.
+         *
+         * The probe request mechanism for ADDBA is currently not implemented,
+         * but we only build up Block Ack session with HT STAs. This information
+         * is set when we receive a bss info from a probe response or a beacon.
+         */
+        if (sta->sdata->vif.type == NL80211_IFTYPE_ADHOC &&
+            !sta->sta.ht_cap.ht_supported) {
+#ifdef CONFIG_MAC80211_HT_DEBUG
+                printk(KERN_DEBUG "BA request denied - IBSS STA %pM"
+                       "does not advertise HT support\n", pubsta->addr);
+#endif /* CONFIG_MAC80211_HT_DEBUG */
+                return -EINVAL;
+        }
+
         spin_lock_bh(&sta->lock);
 
         /* we have tried too many times, receiver does not want A-MPDU */
diff --git a/net/mac80211/ibss.c b/net/mac80211/ibss.c
index 7d84af70132..a82f6b4adb5 100644
--- a/net/mac80211/ibss.c
+++ b/net/mac80211/ibss.c
@@ -896,6 +896,7 @@ int ieee80211_ibss_join(struct ieee80211_sub_if_data *sdata,
                         struct cfg80211_ibss_params *params)
 {
         struct sk_buff *skb;
+        u32 changed = 0;
 
         skb = dev_alloc_skb(sdata->local->hw.extra_tx_headroom +
                             36 /* bitrates */ +
@@ -951,6 +952,23 @@ int ieee80211_ibss_join(struct ieee80211_sub_if_data *sdata,
         ieee80211_recalc_idle(sdata->local);
         mutex_unlock(&sdata->local->mtx);
 
+        /*
+         * 802.11n-2009 9.13.3.1: In an IBSS, the HT Protection field is
+         * reserved, but an HT STA shall protect HT transmissions as though
+         * the HT Protection field were set to non-HT mixed mode.
+         *
+         * In an IBSS, the RIFS Mode field of the HT Operation element is
+         * also reserved, but an HT STA shall operate as though this field
+         * were set to 1.
+         */
+
+        sdata->vif.bss_conf.ht_operation_mode |=
+                  IEEE80211_HT_OP_MODE_PROTECTION_NONHT_MIXED
+                | IEEE80211_HT_PARAM_RIFS_MODE;
+
+        changed |= BSS_CHANGED_HT;
+        ieee80211_bss_info_change_notify(sdata, changed);
+
         ieee80211_queue_work(&sdata->local->hw, &sdata->work);
 
         return 0;
diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index 5243c2cadee..ac7ea2949de 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -1587,6 +1587,11 @@ u8 *ieee80211_ie_build_ht_info(u8 *pos,
         }
         if (ht_cap->cap & IEEE80211_HT_CAP_SUP_WIDTH_20_40)
                 ht_info->ht_param |= IEEE80211_HT_PARAM_CHAN_WIDTH_ANY;
+
+        /*
+         * Note: According to 802.11n-2009 9.13.3.1, HT Protection field and
+         * RIFS Mode are reserved in IBSS mode, therefore keep them at 0
+         */
         ht_info->operation_mode = 0x0000;
         ht_info->stbc_param = 0x0000;