[PATCH v2 1/4] band: generate HT chandef from frequency

[PATCH v2 1/4] band: generate HT chandef from frequency

[James Prestwood]

For AP mode its convenient for IWD to choose an appropriate
channel definition rather than require the user provide very
low level parameters such as channel width, center1 frequency
etc. For now only HT is supported as VHT/HE etc. require
additional secondary channel frequencies.

The HT API tries to find an operating class using 40Mhz which
complies with any hardware restrictions. If an operating class is
found that is supported/not restricted it is marked as 'best' until
a better one is found. In this case 'better' is a larger channel
width. Since this is HT only 20mhz and 40mhz widths are checked.
---
 src/band.c | 87 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/band.h |  2 ++
 2 files changed, 89 insertions(+)

v2:
 * Removed the non-HT API entirely since the caller can set the
   chandef directly after validating the frequency

diff --git a/src/band.c b/src/band.c
index 53ce9495..c89762a9 100644
--- a/src/band.c
+++ b/src/band.c
@@ -1194,6 +1194,93 @@ int oci_from_chandef(const struct band_chandef *own, uint8_t oci[static 3])
 	return -ENOENT;
 }
 
+/* Find an HT chandef for the frequency */
+int band_freq_to_ht_chandef(uint32_t freq, const struct band_freq_attrs *attr,
+				struct band_chandef *chandef)
+{
+	enum band_freq band;
+	enum band_chandef_width width;
+	unsigned int i;
+	const struct operating_class_info *best = NULL;
+
+	if (attr->disabled || !attr->supported)
+		return -EINVAL;
+
+	if (!band_freq_to_channel(freq, &band))
+		return -EINVAL;
+
+	for (i = 0; i < L_ARRAY_SIZE(e4_operating_classes); i++) {
+		const struct operating_class_info *info =
+						&e4_operating_classes[i];
+		enum band_chandef_width w;
+
+		if (e4_has_frequency(info, freq) < 0)
+			continue;
+
+		/* Any restrictions for this channel width? */
+		switch (info->channel_spacing) {
+		case 20:
+			w = BAND_CHANDEF_WIDTH_20;
+			break;
+		case 40:
+			w = BAND_CHANDEF_WIDTH_40;
+
+			/* 6GHz remove the upper/lower 40mhz channel concept */
+			if (band == BAND_FREQ_6_GHZ)
+				break;
+
+			if (info->flags & PRIMARY_CHANNEL_UPPER &&
+						attr->no_ht40_plus)
+				continue;
+
+			if (info->flags & PRIMARY_CHANNEL_LOWER &&
+						attr->no_ht40_minus)
+				continue;
+
+			break;
+		default:
+			continue;
+		}
+
+		if (!best || best->channel_spacing < info->channel_spacing) {
+			best = info;
+			width = w;
+		}
+	}
+
+	if (!best)
+		return -ENOENT;
+
+	chandef->frequency = freq;
+	chandef->channel_width = width;
+
+	/*
+	 * Choose a secondary channel frequency:
+	 * - 20mhz no secondary
+	 * - 40mhz we can base the selection off the channel flags, either
+	 *   higher or lower.
+	 */
+	switch (width) {
+	case BAND_CHANDEF_WIDTH_20:
+		return 0;
+	case BAND_CHANDEF_WIDTH_40:
+		if (band == BAND_FREQ_6_GHZ)
+			return 0;
+
+		if (best->flags & PRIMARY_CHANNEL_UPPER)
+			chandef->center1_frequency = freq - 10;
+		else
+			chandef->center1_frequency = freq + 10;
+
+		return 0;
+	default:
+		/* Should never happen */
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 uint8_t band_freq_to_channel(uint32_t freq, enum band_freq *out_band)
 {
 	uint32_t channel = 0;
diff --git a/src/band.h b/src/band.h
index 0ae5f8c0..676c63d9 100644
--- a/src/band.h
+++ b/src/band.h
@@ -101,6 +101,8 @@ int band_estimate_nonht_rate(const struct band *band,
 				const uint8_t *supported_rates,
 				const uint8_t *ext_supported_rates,
 				int32_t rssi, uint64_t *out_data_rate);
+int band_freq_to_ht_chandef(uint32_t freq, const struct band_freq_attrs *attr,
+				struct band_chandef *chandef);
 
 int oci_to_frequency(uint32_t operating_class, uint32_t channel);
 
-- 
2.34.3

[PATCH v2 2/4] ap: include WMM parameter IE

[James Prestwood]

The WMM parameter IE is expected by the linux kernel for any AP
supporting HT/VHT etc. IWD won't actually use WMM and its not
clear exactly why the kernel uses this restriction, but regardless
it must be included to support HT.
---
 src/ap.c | 71 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 71 insertions(+)

v2:
 * Added big endian block to packed structure.

diff --git a/src/ap.c b/src/ap.c
index 595c71c9..b505499d 100644
--- a/src/ap.c
+++ b/src/ap.c
@@ -111,6 +111,7 @@ struct ap_state {
 	bool in_event : 1;
 	bool free_pending : 1;
 	bool scanning : 1;
+	bool supports_ht : 1;
 };
 
 struct sta_state {
@@ -834,6 +835,9 @@ static size_t ap_get_extra_ies_len(struct ap_state *ap,
 
 	len += ap_get_wsc_ie_len(ap, type, client_frame, client_frame_len);
 
+	if (ap->supports_ht)
+		len += 26;
+
 	if (ap->ops->get_extra_ies_len)
 		len += ap->ops->get_extra_ies_len(type, client_frame,
 							client_frame_len,
@@ -842,6 +846,67 @@ static size_t ap_get_extra_ies_len(struct ap_state *ap,
 	return len;
 }
 
+/* WMM Specification 2.2.2 WMM Parameter Element */
+struct ap_wmm_ac_record {
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+	uint8_t aifsn : 4;
+	uint8_t acm : 1;
+	uint8_t aci : 2;
+	uint8_t reserved : 1;
+	uint8_t ecw_min : 4;
+	uint8_t ecw_max : 4;
+#elif defined (__BIG_ENDIAN_BITFIELD)
+	uint8_t reserved : 1;
+	uint8_t aci : 2;
+	uint8_t acm : 1;
+	uint8_t aifsn : 4;
+	uint8_t acw_max : 4;
+	uint8_t acw_min : 4;
+#else
+#error "Please fix <asm/byteorder.h"
+#endif
+	__le16 txop_limit;
+} __attribute__((packed));
+
+static size_t ap_write_wmm_ies(struct ap_state *ap, uint8_t *out_buf)
+{
+	unsigned int i;
+	struct wiphy *wiphy = netdev_get_wiphy(ap->netdev);
+
+	/*
+	 * Linux kernel requires APs include WMM Information element if
+	 * supporting HT/VHT/etc.
+	 *
+	 * The only value we can actually get from the kernel is UAPSD. The
+	 * remaining values (AC parameter records) are made up or defaults
+	 * defined in the WMM spec are used.
+	 */
+	*out_buf++ = IE_TYPE_VENDOR_SPECIFIC;
+	*out_buf++ = 24;
+	memcpy(out_buf, microsoft_oui, sizeof(microsoft_oui));
+	out_buf += sizeof(microsoft_oui);
+	*out_buf++ = 2; /* WMM OUI Type */
+	*out_buf++ = 1; /* WMM Parameter subtype */
+	*out_buf++ = 1; /* WMM Version */
+	*out_buf++ = wiphy_supports_uapsd(wiphy) ? 1 << 7 : 0;
+	*out_buf++ = 0; /* reserved */
+
+	for (i = 0; i < 4; i++) {
+		struct ap_wmm_ac_record ac = { 0 };
+
+		ac.aifsn = 2;
+		ac.acm = 0;
+		ac.aci = i;
+		ac.ecw_min = 1;
+		ac.ecw_max = 15;
+		l_put_le16(0, &ac.txop_limit);
+
+		memcpy(out_buf + (i * 4), &ac, sizeof(struct ap_wmm_ac_record));
+	}
+
+	return 26;
+}
+
 static size_t ap_write_extra_ies(struct ap_state *ap,
 					enum mpdu_management_subtype type,
 					const struct mmpdu_header *client_frame,
@@ -853,6 +918,9 @@ static size_t ap_write_extra_ies(struct ap_state *ap,
 	len += ap_write_wsc_ie(ap, type, client_frame, client_frame_len,
 				out_buf + len);
 
+	if (ap->supports_ht)
+		len += ap_write_wmm_ies(ap, out_buf + len);
+
 	if (ap->ops->write_extra_ies)
 		len += ap->ops->write_extra_ies(type,
 						client_frame, client_frame_len,
@@ -3255,6 +3323,9 @@ static int ap_load_config(struct ap_state *ap, const struct l_settings *config,
 		ap->band = BAND_FREQ_2_4_GHZ;
 	}
 
+	ap->supports_ht = wiphy_get_ht_capabilities(wiphy, ap->band,
+							NULL) != NULL;
+
 	if (!ap_validate_band_channel(ap)) {
 		l_error("AP Band and Channel combination invalid");
 		return -EINVAL;
-- 
2.34.3

[PATCH v2 3/4] ap: build HT Capabilities/Operation elements

[James Prestwood]

If supported this will include the HT capabilities and HT
operations elements in beacons/probes. Some shortcuts were taken
here since not all the information is currently parsed from the
hardware. Namely the HT operation element does not include the
basic MCS set. Still, this will at least show stations that the
AP is capable of more than just basic rates.

The builders themselves are structured similar to the basic rates
builder where they build only the contents and return the length.
The caller must set the type/length manually. This is to support
the two use cases of using with an IE builder vs direct pointer.
---
 src/ap.c | 104 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 104 insertions(+)

diff --git a/src/ap.c b/src/ap.c
index b505499d..d9a81651 100644
--- a/src/ap.c
+++ b/src/ap.c
@@ -136,6 +136,9 @@ struct sta_state {
 	bool wsc_v2;
 	struct l_dhcp_lease *ip_alloc_lease;
 	bool ip_alloc_sent;
+
+	bool ht_support : 1;
+	bool ht_greenfield : 1;
 };
 
 struct ap_wsc_pbc_probe_record {
@@ -929,6 +932,66 @@ static size_t ap_write_extra_ies(struct ap_state *ap,
 	return len;
 }
 
+static size_t ap_build_ht_capability(struct ap_state *ap, uint8_t *buf)
+{
+	struct wiphy *wiphy = netdev_get_wiphy(ap->netdev);
+	size_t ht_capa_len;
+	const uint8_t *ht_capa = wiphy_get_ht_capabilities(wiphy, ap->band,
+								&ht_capa_len);
+
+	memcpy(buf, ht_capa, ht_capa_len);
+
+	return ht_capa_len;
+}
+
+static size_t ap_build_ht_operation(struct ap_state *ap, uint8_t *buf)
+{
+	const struct l_queue_entry *e;
+	unsigned int non_ht = false;
+	unsigned int non_greenfield = false;
+
+	memset(buf, 0, 22);
+	*buf++ = ap->channel;
+
+	/*
+	 * If 40MHz set 'Secondary Channel Offset' (bits 0-1) to above/below
+	 * and set 'STA Channel Width' (bit 2) to indicate non-20Mhz.
+	 */
+	if (ap->chandef.channel_width == BAND_CHANDEF_WIDTH_20)
+		goto check_stas;
+	else if (ap->chandef.frequency < ap->chandef.center1_frequency)
+		*buf |= 1 & 0x3;
+	else
+		*buf |= 3 & 0x3;
+
+	*buf |= 1 << 2;
+
+check_stas:
+	for (e = l_queue_get_entries(ap->sta_states); e; e = e->next) {
+		struct sta_state *sta = e->data;
+
+		if (!sta->associated)
+			continue;
+
+		if (!sta->ht_support)
+			non_ht = true;
+		else if (!sta->ht_greenfield)
+			non_greenfield = true;
+	}
+
+	if (non_greenfield)
+		set_bit(buf, 10);
+
+	if (non_ht)
+		set_bit(buf, 12);
+
+	/*
+	 * TODO: Basic MCS set for all associated STAs
+	 */
+
+	return 22;
+}
+
 /*
  * Build a Beacon frame or a Probe Response frame's header and body until
  * the TIM IE.  Except for the optional TIM IE which is inserted by the
@@ -981,6 +1044,18 @@ static size_t ap_build_beacon_pr_head(struct ap_state *ap,
 	ie_tlv_builder_next(&builder, IE_TYPE_DSSS_PARAMETER_SET);
 	ie_tlv_builder_set_data(&builder, &ap->channel, 1);
 
+	if (ap->supports_ht) {
+		ie_tlv_builder_next(&builder, IE_TYPE_HT_CAPABILITIES);
+		len = ap_build_ht_capability(ap,
+					ie_tlv_builder_get_data(&builder));
+		ie_tlv_builder_set_length(&builder, len);
+
+		ie_tlv_builder_next(&builder, IE_TYPE_HT_OPERATION);
+		len = ap_build_ht_operation(ap,
+					ie_tlv_builder_get_data(&builder));
+		ie_tlv_builder_set_length(&builder, len);
+	}
+
 	ie_tlv_builder_finalize(&builder, &out_len);
 	return 36 + out_len;
 }
@@ -1639,6 +1714,18 @@ static uint32_t ap_assoc_resp(struct ap_state *ap, struct sta_state *sta,
 	resp->ies[ies_len++] = len;
 	ies_len += len;
 
+	if (ap->supports_ht) {
+		resp->ies[ies_len++] = IE_TYPE_HT_CAPABILITIES;
+		len = ap_build_ht_capability(ap, resp->ies + ies_len + 1);
+		resp->ies[ies_len++] = len;
+		ies_len += len;
+
+		resp->ies[ies_len++] = IE_TYPE_HT_OPERATION;
+		len = ap_build_ht_operation(ap, resp->ies + ies_len + 1);
+		resp->ies[ies_len++] = len;
+		ies_len += len;
+	}
+
 	ies_len += ap_write_extra_ies(ap, stype, req, req_len,
 					resp->ies + ies_len);
 
@@ -1844,6 +1931,17 @@ static void ap_assoc_reassoc(struct sta_state *sta, bool reassoc,
 
 			fils_ip_req = true;
 			break;
+		case IE_TYPE_HT_CAPABILITIES:
+			if (ie_tlv_iter_get_length(&iter) != 26) {
+				err = MMPDU_REASON_CODE_INVALID_IE;
+				goto bad_frame;
+			}
+
+			if (test_bit(ie_tlv_iter_get_data(&iter), 4))
+				sta->ht_greenfield = true;
+
+			sta->ht_support = true;
+			break;
 		}
 
 	if (!rates || !ssid || (!wsc_data && !rsn) ||
@@ -2687,6 +2785,9 @@ static void ap_handle_new_station(struct ap_state *ap, struct l_genl_msg *msg)
 
 	l_queue_push_tail(ap->sta_states, sta);
 
+	if (ap->supports_ht)
+		ap_update_beacon(ap);
+
 	msg = nl80211_build_set_station_unauthorized(
 					netdev_get_ifindex(ap->netdev), mac);
 
@@ -3723,6 +3824,9 @@ bool ap_station_disconnect(struct ap_state *ap, const uint8_t *mac,
 	if (!sta)
 		return false;
 
+	if (ap->supports_ht)
+		ap_update_beacon(ap);
+
 	ap_del_station(sta, reason, false);
 	ap_sta_free(sta);
 	return true;
-- 
2.34.3

[PATCH v2 4/4] ap: generate chandef for starting AP

[James Prestwood]

To include HT support a chandef needs to be created for whatever
frequency is being used. This allows IWD to provide a secondary
channel to the kernel in the case of 40MHz operation. Now the AP
will generate a chandef when starting based on the channel set
in the user profile (or default).

If HT is not supported the chandef width is set to 20MHz no-HT,
otherwise band_freq_to_ht_chandef is used.
---
 src/ap.c | 38 ++++++++++++++++++++++++++++++++++----
 1 file changed, 34 insertions(+), 4 deletions(-)

v2:
 * Create chandef manually for non-HT since its very simple
 * Fall back to non-HT in the unlikely event the HT chandef
   fails to be created

diff --git a/src/ap.c b/src/ap.c
index d9a81651..a989c454 100644
--- a/src/ap.c
+++ b/src/ap.c
@@ -72,6 +72,7 @@ struct ap_state {
 	uint8_t psk[32];
 	enum band_freq band;
 	uint8_t channel;
+	struct band_chandef chandef;
 	uint8_t *authorized_macs;
 	unsigned int authorized_macs_num;
 	char wsc_name[33];
@@ -2567,8 +2568,6 @@ static struct l_genl_msg *ap_build_cmd_start_ap(struct ap_state *ap)
 	uint32_t nl_akm = CRYPTO_AKM_PSK;
 	uint32_t wpa_version = NL80211_WPA_VERSION_2;
 	uint32_t auth_type = NL80211_AUTHTYPE_OPEN_SYSTEM;
-	uint32_t ch_freq = band_channel_to_freq(ap->channel, ap->band);
-	uint32_t ch_width = NL80211_CHAN_WIDTH_20;
 	unsigned int i;
 
 	static const uint8_t bcast_addr[6] = {
@@ -2616,8 +2615,13 @@ static struct l_genl_msg *ap_build_cmd_start_ap(struct ap_state *ap)
 	l_genl_msg_append_attr(cmd, NL80211_ATTR_WPA_VERSIONS, 4, &wpa_version);
 	l_genl_msg_append_attr(cmd, NL80211_ATTR_AKM_SUITES, 4, &nl_akm);
 	l_genl_msg_append_attr(cmd, NL80211_ATTR_AUTH_TYPE, 4, &auth_type);
-	l_genl_msg_append_attr(cmd, NL80211_ATTR_WIPHY_FREQ, 4, &ch_freq);
-	l_genl_msg_append_attr(cmd, NL80211_ATTR_CHANNEL_WIDTH, 4, &ch_width);
+	l_genl_msg_append_attr(cmd, NL80211_ATTR_WIPHY_FREQ, 4,
+				&ap->chandef.frequency);
+	l_genl_msg_append_attr(cmd, NL80211_ATTR_CHANNEL_WIDTH, 4,
+				&ap->chandef.channel_width);
+	if (ap->chandef.center1_frequency)
+		l_genl_msg_append_attr(cmd, NL80211_ATTR_CENTER_FREQ1, 4,
+					&ap->chandef.center1_frequency);
 
 	if (wiphy_supports_probe_resp_offload(wiphy)) {
 		uint8_t probe_resp[head_len + tail_len];
@@ -3356,6 +3360,32 @@ static bool ap_validate_band_channel(struct ap_state *ap)
 		l_error("AP frequency %u disabled or unsupported", freq);
 		return false;
 	}
+
+	if (ap->supports_ht) {
+		if (band_freq_to_ht_chandef(freq, attr, &ap->chandef) < 0) {
+			/*
+			 * This is unlikely ever to fail since there are no
+			 * 20Mhz restrictions, but just in case fall back to
+			 * non-HT.
+			 */
+			ap->supports_ht = false;
+
+			l_warn("AP could not find HT chandef for frequency %u"
+				" using 20Mhz no-HT", freq);
+
+			goto no_ht;
+		}
+	} else {
+no_ht:
+		ap->chandef.frequency = freq;
+		ap->chandef.channel_width = BAND_CHANDEF_WIDTH_20NOHT;
+	}
+
+	l_debug("AP using frequency %u and channel width %s",
+			ap->chandef.frequency,
+			band_chandef_width_to_string(
+				ap->chandef.channel_width));
+
 	return true;
 }
 
-- 
2.34.3