mac80211: handle HT PHY BSS membership selector value correctly

802.11n-2009 extends the supported rates element with a
magic value which can be used to prevent legacy stations
from joining the BSS.

However, this magic value is not a rate like the others
and the magic can simply be ignored/skipped at this late
stage.

Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>---
Signed-off-by: John W. Linville <linville@tuxdriver.com>

diff --git a/include/linux/ieee80211.h b/include/linux/ieee80211.h
index 48363c3..9789aed 100644 (file)
--- a/include/linux/ieee80211.h
+++ b/include/linux/ieee80211.h
@@ -770,6 +770,9 @@ struct ieee80211_mgmt {
        } u;
 } __attribute__ ((packed));
 
+/* Supported Rates value encodings in 802.11n-2009 7.3.2.2 */
+#define BSS_MEMBERSHIP_SELECTOR_HT_PHY 127
+
 /* mgmt header + 1 byte category code */
 #define IEEE80211_MIN_ACTION_SIZE offsetof(struct ieee80211_mgmt, u.action.u)
 

diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index d3b408c..b25567a 100644 (file)
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -1466,6 +1466,47 @@ ieee80211_rx_mgmt_disassoc(struct ieee80211_sub_if_data *sdata,
        return RX_MGMT_CFG80211_DISASSOC;
 }
 
+static void ieee80211_get_rates(struct ieee80211_supported_band *sband,
+                               u8 *supp_rates, unsigned int supp_rates_len,
+                               u32 *rates, u32 *basic_rates,
+                               bool *have_higher_than_11mbit,
+                               int *min_rate, int *min_rate_index)
+{
+       int i, j;
+
+       for (i = 0; i < supp_rates_len; i++) {
+               int rate = (supp_rates[i] & 0x7f) * 5;
+               bool is_basic = !!(supp_rates[i] & 0x80);
+
+               if (rate > 110)
+                       *have_higher_than_11mbit = true;
+
+               /*
+                * BSS_MEMBERSHIP_SELECTOR_HT_PHY is defined in 802.11n-2009
+                * 7.3.2.2 as a magic value instead of a rate. Hence, skip it.
+                *
+                * Note: Even through the membership selector and the basic
+                *       rate flag share the same bit, they are not exactly
+                *       the same.
+                */
+               if (!!(supp_rates[i] & 0x80) &&
+                   (supp_rates[i] & 0x7f) == BSS_MEMBERSHIP_SELECTOR_HT_PHY)
+                       continue;
+
+               for (j = 0; j < sband->n_bitrates; j++) {
+                       if (sband->bitrates[j].bitrate == rate) {
+                               *rates |= BIT(j);
+                               if (is_basic)
+                                       *basic_rates |= BIT(j);
+                               if (rate < *min_rate) {
+                                       *min_rate = rate;
+                                       *min_rate_index = j;
+                               }
+                               break;
+                       }
+               }
+       }
+}
 
 static bool ieee80211_assoc_success(struct ieee80211_work *wk,
                                    struct ieee80211_mgmt *mgmt, size_t len)
@@ -1482,7 +1523,7 @@ static bool ieee80211_assoc_success(struct ieee80211_work *wk,
        struct ieee802_11_elems elems;
        struct ieee80211_bss_conf *bss_conf = &sdata->vif.bss_conf;
        u32 changed = 0;
-       int i, j, err;
+       int err;
        bool have_higher_than_11mbit = false;
        u16 ap_ht_cap_flags;
        int min_rate = INT_MAX, min_rate_index = -1;
@@ -1540,47 +1581,14 @@ static bool ieee80211_assoc_success(struct ieee80211_work *wk,
        basic_rates = 0;
        sband = local->hw.wiphy->bands[wk->chan->band];
 
-       for (i = 0; i < elems.supp_rates_len; i++) {
-               int rate = (elems.supp_rates[i] & 0x7f) * 5;
-               bool is_basic = !!(elems.supp_rates[i] & 0x80);
-
-               if (rate > 110)
-                       have_higher_than_11mbit = true;
+       ieee80211_get_rates(sband, elems.supp_rates, elems.supp_rates_len,
+                           &rates, &basic_rates, &have_higher_than_11mbit,
+                           &min_rate, &min_rate_index);
 
-               for (j = 0; j < sband->n_bitrates; j++) {
-                       if (sband->bitrates[j].bitrate == rate) {
-                               rates |= BIT(j);
-                               if (is_basic)
-                                       basic_rates |= BIT(j);
-                               if (rate < min_rate) {
-                                       min_rate = rate;
-                                       min_rate_index = j;
-                               }
-                               break;
-                       }
-               }
-       }
-
-       for (i = 0; i < elems.ext_supp_rates_len; i++) {
-               int rate = (elems.ext_supp_rates[i] & 0x7f) * 5;
-               bool is_basic = !!(elems.ext_supp_rates[i] & 0x80);
-
-               if (rate > 110)
-                       have_higher_than_11mbit = true;
-
-               for (j = 0; j < sband->n_bitrates; j++) {
-                       if (sband->bitrates[j].bitrate == rate) {
-                               rates |= BIT(j);
-                               if (is_basic)
-                                       basic_rates |= BIT(j);
-                               if (rate < min_rate) {
-                                       min_rate = rate;
-                                       min_rate_index = j;
-                               }
-                               break;
-                       }
-               }
-       }
+       ieee80211_get_rates(sband, elems.ext_supp_rates,
+                           elems.ext_supp_rates_len, &rates, &basic_rates,
+                           &have_higher_than_11mbit,
+                           &min_rate, &min_rate_index);
 
        /*
         * some buggy APs don't advertise basic_rates. use the lowest