wpa_supplicant: Add support for VHT BSS membership selector

This allows wpa_supplicant to associate to an AP that has VHT BSS
membership selector set to indicate VHT support is required for the BSS.

Without the patch it was impossible to connect to, e.g., hostapd-based
AP that has require_vht=1. wpa_supplicant was complaining with:
  hardware does not support required rate 63.0 Mbps

Signed-hostap: Michal Kazior <michal.kazior@tieto.com>

src/drivers/driver.h

@@ -61,6 +61,7 @@ struct hostapd_channel_data {
 };
 
 #define HOSTAPD_MODE_FLAG_HT_INFO_KNOWN BIT(0)
+#define HOSTAPD_MODE_FLAG_VHT_INFO_KNOWN BIT(1)
 
 /**
  * struct hostapd_hw_modes - Supported hardware mode information

src/drivers/driver_nl80211.c

@@ -5658,7 +5658,20 @@ static int phy_info_band(struct phy_info_arg *phy_info, struct nlattr *nl_band)
 		mode = &phy_info->modes[*(phy_info->num_modes)];
 		os_memset(mode, 0, sizeof(*mode));
 		mode->mode = NUM_HOSTAPD_MODES;
-		mode->flags = HOSTAPD_MODE_FLAG_HT_INFO_KNOWN;
+		mode->flags = HOSTAPD_MODE_FLAG_HT_INFO_KNOWN |
+			HOSTAPD_MODE_FLAG_VHT_INFO_KNOWN;
+
+		/*
+		 * Unsupported VHT MCS stream is defined as value 3, so the VHT
+		 * MCS RX/TX map must be initialized with 0xffff to mark all 8
+		 * possible streams as unsupported. This will be overridden if
+		 * driver advertises VHT support.
+		 */
+		mode->vht_mcs_set[0] = 0xff;
+		mode->vht_mcs_set[1] = 0xff;
+		mode->vht_mcs_set[4] = 0xff;
+		mode->vht_mcs_set[5] = 0xff;
+
 		*(phy_info->num_modes) += 1;
 		phy_info->last_mode = nl_band->nla_type;
 		phy_info->last_chan_idx = 0;

wpa_supplicant/events.c

@@ -548,6 +548,24 @@ static int ht_supported(const struct hostapd_hw_modes *mode)
 }
 
 
+static int vht_supported(const struct hostapd_hw_modes *mode)
+{
+	if (!(mode->flags & HOSTAPD_MODE_FLAG_VHT_INFO_KNOWN)) {
+		/*
+		 * The driver did not indicate whether it supports VHT. Assume
+		 * it does to avoid connection issues.
+		 */
+		return 1;
+	}
+
+	/*
+	 * A VHT non-AP STA shall support MCS 0-7 for one spatial stream.
+	 * TODO: Verify if this complies with the standard
+	 */
+	return (mode->vht_mcs_set[0] & 0x3) != 3;
+}
+
+
 static int rate_match(struct wpa_supplicant *wpa_s, struct wpa_bss *bss)
 {
 	const struct hostapd_hw_modes *mode = NULL, *modes;
@@ -613,6 +631,18 @@ static int rate_match(struct wpa_supplicant *wpa_s, struct wpa_bss *bss)
 				continue;
 			}
 
+			/* There's also a VHT selector for 802.11ac */
+			if (flagged && ((rate_ie[j] & 0x7f) ==
+					BSS_MEMBERSHIP_SELECTOR_VHT_PHY)) {
+				if (!vht_supported(mode)) {
+					wpa_dbg(wpa_s, MSG_DEBUG,
+						"   hardware does not support "
+						"VHT PHY");
+					return 0;
+				}
+				continue;
+			}
+
 			if (!flagged)
 				continue;