From c74d084f914e16e42730bcf625ab3f37a4cae8d4 Mon Sep 17 00:00:00 2001 From: Christian Lamparter Date: Sat, 15 Oct 2011 00:14:49 +0200 Subject: [PATCH] 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 --- Signed-off-by: John W. Linville --- include/linux/ieee80211.h | 3 ++ net/mac80211/mlme.c | 90 +++++++++++++++++++++------------------ 2 files changed, 52 insertions(+), 41 deletions(-) diff --git a/include/linux/ieee80211.h b/include/linux/ieee80211.h index 48363c3c40f..9789aedb245 100644 --- 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 d3b408cda08..b25567a32f9 100644 --- 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 -- 2.20.1