mac80211: allow disable FAT in specific configurations

This patch allows to disable FAT channel in specific configurations.

For example the configuration (8, +1), (primary channel 8, extension
channel 12) isn't permitted in U.S., but (8, -1), (primary channel 8,
extension channel 4) is. When FAT channel configuration is not
permitted, FAT channel should be reported as not supported in the
capabilities of the HT IE in association request. And sssociation is
performed on 20Mhz channel.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

4 files changed, 54 insertions, 2 deletions

diff --git a/include/linux/ieee80211.h b/include/linux/ieee80211.h
index 3c2ac0c37aa8..9300f37cd7e8 100644
--- a/include/linux/ieee80211.h
+++ b/include/linux/ieee80211.h
@@ -320,6 +320,8 @@ struct ieee80211_ht_addt_info {
 #define IEEE80211_HT_CAP_MCS_TX_UEQM            0x10
 /* 802.11n HT IE masks */
 #define IEEE80211_HT_IE_CHA_SEC_OFFSET          0x03
+#define IEEE80211_HT_IE_CHA_SEC_ABOVE           0x01
+#define IEEE80211_HT_IE_CHA_SEC_BELOW           0x03
 #define IEEE80211_HT_IE_CHA_WIDTH               0x04
 #define IEEE80211_HT_IE_HT_PROTECTION           0x0003
 #define IEEE80211_HT_IE_NON_GF_STA_PRSNT        0x0004
diff --git a/include/net/wireless.h b/include/net/wireless.h
index 667b4080d30f..9324f8dd183e 100644
--- a/include/net/wireless.h
+++ b/include/net/wireless.h
@@ -39,12 +39,18 @@ enum ieee80211_band {
  *      on this channel.
  * @IEEE80211_CHAN_NO_IBSS: IBSS is not allowed on this channel.
  * @IEEE80211_CHAN_RADAR: Radar detection is required on this channel.
+ * @IEEE80211_CHAN_NO_FAT_ABOVE: extension channel above this channel
+ *      is not permitted.
+ * @IEEE80211_CHAN_NO_FAT_BELOW: extension channel below this channel
+ *      is not permitted.
  */
 enum ieee80211_channel_flags {
         IEEE80211_CHAN_DISABLED         = 1<<0,
         IEEE80211_CHAN_PASSIVE_SCAN     = 1<<1,
         IEEE80211_CHAN_NO_IBSS          = 1<<2,
         IEEE80211_CHAN_RADAR            = 1<<3,
+        IEEE80211_CHAN_NO_FAT_ABOVE     = 1<<4,
+        IEEE80211_CHAN_NO_FAT_BELOW     = 1<<5,
 };
 
 /**
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 3f8601cafffb..432011cd3647 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -92,6 +92,8 @@ struct ieee80211_sta_bss {
         size_t wmm_ie_len;
         u8 *ht_ie;
         size_t ht_ie_len;
+        u8 *ht_add_ie;
+        size_t ht_add_ie_len;
 #ifdef CONFIG_MAC80211_MESH
         u8 *mesh_id;
         size_t mesh_id_len;
diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index 6faa7006681a..d30c11337b04 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -808,8 +808,29 @@ static void ieee80211_send_assoc(struct net_device *dev,
 
         /* wmm support is a must to HT */
         if (wmm && (ifsta->flags & IEEE80211_STA_WMM_ENABLED) &&
-            sband->ht_info.ht_supported) {
-                __le16 tmp = cpu_to_le16(sband->ht_info.cap);
+            sband->ht_info.ht_supported && bss->ht_add_ie) {
+                struct ieee80211_ht_addt_info *ht_add_info =
+                        (struct ieee80211_ht_addt_info *)bss->ht_add_ie;
+                u16 cap = sband->ht_info.cap;
+                __le16 tmp;
+                u32 flags = local->hw.conf.channel->flags;
+
+                switch (ht_add_info->ht_param & IEEE80211_HT_IE_CHA_SEC_OFFSET) {
+                case IEEE80211_HT_IE_CHA_SEC_ABOVE:
+                        if (flags & IEEE80211_CHAN_NO_FAT_ABOVE) {
+                                cap &= ~IEEE80211_HT_CAP_SUP_WIDTH;
+                                cap &= ~IEEE80211_HT_CAP_SGI_40;
+                        }
+                        break;
+                case IEEE80211_HT_IE_CHA_SEC_BELOW:
+                        if (flags & IEEE80211_CHAN_NO_FAT_BELOW) {
+                                cap &= ~IEEE80211_HT_CAP_SUP_WIDTH;
+                                cap &= ~IEEE80211_HT_CAP_SGI_40;
+                        }
+                        break;
+                }
+
+                tmp = cpu_to_le16(cap);
                 pos = skb_put(skb, sizeof(struct ieee80211_ht_cap)+2);
                 *pos++ = WLAN_EID_HT_CAPABILITY;
                 *pos++ = sizeof(struct ieee80211_ht_cap);
@@ -2264,6 +2285,7 @@ static void ieee80211_rx_bss_free(struct ieee80211_sta_bss *bss)
         kfree(bss->rsn_ie);
         kfree(bss->wmm_ie);
         kfree(bss->ht_ie);
+        kfree(bss->ht_add_ie);
         kfree(bss_mesh_id(bss));
         kfree(bss_mesh_cfg(bss));
         kfree(bss);
@@ -2640,6 +2662,26 @@ static void ieee80211_rx_bss_info(struct net_device *dev,
                 bss->ht_ie_len = 0;
         }
 
+        if (elems.ht_info_elem &&
+             (!bss->ht_add_ie ||
+             bss->ht_add_ie_len != elems.ht_info_elem_len ||
+             memcmp(bss->ht_add_ie, elems.ht_info_elem,
+                        elems.ht_info_elem_len))) {
+                kfree(bss->ht_add_ie);
+                bss->ht_add_ie =
+                        kmalloc(elems.ht_info_elem_len + 2, GFP_ATOMIC);
+                if (bss->ht_add_ie) {
+                        memcpy(bss->ht_add_ie, elems.ht_info_elem - 2,
+                                elems.ht_info_elem_len + 2);
+                        bss->ht_add_ie_len = elems.ht_info_elem_len + 2;
+                } else
+                        bss->ht_add_ie_len = 0;
+        } else if (!elems.ht_info_elem && bss->ht_add_ie) {
+                kfree(bss->ht_add_ie);
+                bss->ht_add_ie = NULL;
+                bss->ht_add_ie_len = 0;
+        }
+
         bss->beacon_int = le16_to_cpu(mgmt->u.beacon.beacon_int);
         bss->capability = le16_to_cpu(mgmt->u.beacon.capab_info);