wifi: mac80211: add RX flag to report radiotap VHT information

mac80211 already reports some basic information in the radiotap header
with the known fields declared by the driver. However, drivers may want
to report more accurate information and in that case the full VHT
radiotap structure needs to be provided.

Add a new RX_FLAG_RADIOTAP_VHT which is set when the VHT information
should be pulled from the skb. Update the code to fill in the VHT fields
to only do so when requested by the driver or if the information has not
yet been set. This way the driver can fully control the information if
it chooses so.

Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Reviewed-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://patch.msgid.link/20251027142118.0bad1c307a21.I2cf285c20a822698039603f2af00ed9c548f2ee0@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 68 insertions, 36 deletions

diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 4641a2a80856..b59aeed340b3 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -59,7 +59,8 @@ static struct sk_buff *ieee80211_clean_skb(struct sk_buff *skb,
 	status->flag &= ~(RX_FLAG_RADIOTAP_TLV_AT_END |
 			  RX_FLAG_RADIOTAP_LSIG |
 			  RX_FLAG_RADIOTAP_HE_MU |
-			  RX_FLAG_RADIOTAP_HE);
+			  RX_FLAG_RADIOTAP_HE |
+			  RX_FLAG_RADIOTAP_VHT);
 
 	hdr = (void *)skb->data;
 	fc = hdr->frame_control;
@@ -151,8 +152,10 @@ ieee80211_rx_radiotap_hdrlen(struct ieee80211_local *local,
 	}
 
 	if (status->encoding == RX_ENC_VHT) {
+		/* Included even if RX_FLAG_RADIOTAP_VHT is not set */
 		len = ALIGN(len, 2);
 		len += 12;
+		BUILD_BUG_ON(sizeof(struct ieee80211_radiotap_vht) != 12);
 	}
 
 	if (local->hw.radiotap_timestamp.units_pos >= 0) {
@@ -195,6 +198,9 @@ ieee80211_rx_radiotap_hdrlen(struct ieee80211_local *local,
 		 * The position to look at depends on the existence (or non-
 		 * existence) of other elements, so take that into account...
 		 */
+		if (status->flag & RX_FLAG_RADIOTAP_VHT)
+			tlv_offset +=
+				sizeof(struct ieee80211_radiotap_vht);
 		if (status->flag & RX_FLAG_RADIOTAP_HE)
 			tlv_offset +=
 				sizeof(struct ieee80211_radiotap_he);
@@ -319,10 +325,17 @@ ieee80211_add_rx_radiotap_header(struct ieee80211_local *local,
 	u32 tlvs_len = 0;
 	int mpdulen, chain;
 	unsigned long chains = status->chains;
+	struct ieee80211_radiotap_vht vht = {};
 	struct ieee80211_radiotap_he he = {};
 	struct ieee80211_radiotap_he_mu he_mu = {};
 	struct ieee80211_radiotap_lsig lsig = {};
 
+	if (status->flag & RX_FLAG_RADIOTAP_VHT) {
+		vht = *(struct ieee80211_radiotap_vht *)skb->data;
+		skb_pull(skb, sizeof(vht));
+		WARN_ON_ONCE(status->encoding != RX_ENC_VHT);
+	}
+
 	if (status->flag & RX_FLAG_RADIOTAP_HE) {
 		he = *(struct ieee80211_radiotap_he *)skb->data;
 		skb_pull(skb, sizeof(he));
@@ -530,45 +543,61 @@ ieee80211_add_rx_radiotap_header(struct ieee80211_local *local,
 	}
 
 	if (status->encoding == RX_ENC_VHT) {
-		u16 known = local->hw.radiotap_vht_details;
+		u16 fill = local->hw.radiotap_vht_details;
 
-		rthdr->it_present |= cpu_to_le32(BIT(IEEE80211_RADIOTAP_VHT));
-		put_unaligned_le16(known, pos);
-		pos += 2;
-		/* flags */
-		if (status->enc_flags & RX_ENC_FLAG_SHORT_GI)
-			*pos |= IEEE80211_RADIOTAP_VHT_FLAG_SGI;
+		/* Leave driver filled fields alone */
+		fill &= ~le16_to_cpu(vht.known);
+		vht.known |= cpu_to_le16(fill);
+
+		if (fill & IEEE80211_RADIOTAP_VHT_KNOWN_GI &&
+		    status->enc_flags & RX_ENC_FLAG_SHORT_GI)
+			vht.flags |= IEEE80211_RADIOTAP_VHT_FLAG_SGI;
 		/* in VHT, STBC is binary */
-		if (status->enc_flags & RX_ENC_FLAG_STBC_MASK)
-			*pos |= IEEE80211_RADIOTAP_VHT_FLAG_STBC;
-		if (status->enc_flags & RX_ENC_FLAG_BF)
+		if (fill & IEEE80211_RADIOTAP_VHT_KNOWN_STBC &&
+		    status->enc_flags & RX_ENC_FLAG_STBC_MASK)
+			vht.flags |= IEEE80211_RADIOTAP_VHT_FLAG_STBC;
+		if (fill & IEEE80211_RADIOTAP_VHT_KNOWN_BEAMFORMED &&
+		    status->enc_flags & RX_ENC_FLAG_BF)
 			*pos |= IEEE80211_RADIOTAP_VHT_FLAG_BEAMFORMED;
-		pos++;
-		/* bandwidth */
-		switch (status->bw) {
-		case RATE_INFO_BW_80:
-			*pos++ = 4;
-			break;
-		case RATE_INFO_BW_160:
-			*pos++ = 11;
-			break;
-		case RATE_INFO_BW_40:
-			*pos++ = 1;
-			break;
-		default:
-			*pos++ = 0;
+
+		if (fill & IEEE80211_RADIOTAP_VHT_KNOWN_BANDWIDTH) {
+			switch (status->bw) {
+			case RATE_INFO_BW_40:
+				vht.bandwidth = IEEE80211_RADIOTAP_VHT_BW_40;
+				break;
+			case RATE_INFO_BW_80:
+				vht.bandwidth = IEEE80211_RADIOTAP_VHT_BW_80;
+				break;
+			case RATE_INFO_BW_160:
+				vht.bandwidth = IEEE80211_RADIOTAP_VHT_BW_160;
+				break;
+			default:
+				vht.bandwidth = IEEE80211_RADIOTAP_VHT_BW_20;
+				break;
+			}
 		}
-		/* MCS/NSS */
-		*pos = (status->rate_idx << 4) | status->nss;
-		pos += 4;
-		/* coding field */
-		if (status->enc_flags & RX_ENC_FLAG_LDPC)
-			*pos |= IEEE80211_RADIOTAP_CODING_LDPC_USER0;
-		pos++;
-		/* group ID */
-		pos++;
-		/* partial_aid */
-		pos += 2;
+
+		/*
+		 * If the driver filled in mcs_nss[0], then do not touch it.
+		 *
+		 * Otherwise, put some information about MCS/NSS into the
+		 * user 0 field. Note that this is not technically correct for
+		 * an MU frame as we might have decoded a different user.
+		 */
+		if (!vht.mcs_nss[0]) {
+			vht.mcs_nss[0] = (status->rate_idx << 4) | status->nss;
+
+			/* coding field */
+			if (status->enc_flags & RX_ENC_FLAG_LDPC)
+				vht.coding |= IEEE80211_RADIOTAP_CODING_LDPC_USER0;
+		}
+
+		/* ensure 2 byte alignment */
+		while ((pos - (u8 *)rthdr) & 1)
+			pos++;
+		rthdr->it_present |= cpu_to_le32(BIT(IEEE80211_RADIOTAP_VHT));
+		memcpy(pos, &vht, sizeof(vht));
+		pos += sizeof(vht);
 	}
 
 	if (local->hw.radiotap_timestamp.units_pos >= 0) {
@@ -834,6 +863,9 @@ ieee80211_rx_monitor(struct ieee80211_local *local, struct sk_buff *origskb,
 		return NULL;
 	}
 
+	if (status->flag & RX_FLAG_RADIOTAP_VHT)
+		rtap_space += sizeof(struct ieee80211_radiotap_vht);
+
 	if (status->flag & RX_FLAG_RADIOTAP_HE)
 		rtap_space += sizeof(struct ieee80211_radiotap_he);