mac80211: support radiotap vendor namespace RX data

In some cases, in particular for experimentation, it
can be useful to be able to add vendor namespace data
to received frames in addition to the normal radiotap
data.

Allow doing this through mac80211 by adding fields to
the RX status descriptor that describe the data while
the data itself is prepended to the frame.

Also add some example code to hwsim, but don't enable
it because it doesn't use a proper OUI identifier.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 59 insertions, 12 deletions

diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 8480bbf1a70..ec15a4929f7 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -40,6 +40,8 @@
 static struct sk_buff *remove_monitor_info(struct ieee80211_local *local,
 					   struct sk_buff *skb)
 {
+	struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
+
 	if (local->hw.flags & IEEE80211_HW_RX_INCLUDES_FCS) {
 		if (likely(skb->len > FCS_LEN))
 			__pskb_trim(skb, skb->len - FCS_LEN);
@@ -51,6 +53,9 @@ static struct sk_buff *remove_monitor_info(struct ieee80211_local *local,
 		}
 	}
 
+	if (status->vendor_radiotap_len)
+		__pskb_pull(skb, status->vendor_radiotap_len);
+
 	return skb;
 }
 
@@ -73,32 +78,48 @@ static inline int should_drop_frame(struct sk_buff *skb, int present_fcs_len)
 }
 
 static int
-ieee80211_rx_radiotap_len(struct ieee80211_local *local,
-			  struct ieee80211_rx_status *status)
+ieee80211_rx_radiotap_space(struct ieee80211_local *local,
+			    struct ieee80211_rx_status *status)
 {
 	int len;
 
 	/* always present fields */
 	len = sizeof(struct ieee80211_radiotap_header) + 9;
 
-	if (ieee80211_have_rx_timestamp(status))
+	/* allocate extra bitmap */
+	if (status->vendor_radiotap_len)
+		len += 4;
+
+	if (ieee80211_have_rx_timestamp(status)) {
+		len = ALIGN(len, 8);
 		len += 8;
+	}
 	if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
 		len += 1;
 
-	if (len & 1) /* padding for RX_FLAGS if necessary */
-		len++;
+	/* padding for RX_FLAGS if necessary */
+	len = ALIGN(len, 2);
 
 	if (status->flag & RX_FLAG_HT) /* HT info */
 		len += 3;
 
 	if (status->flag & RX_FLAG_AMPDU_DETAILS) {
-		/* padding */
-		while (len & 3)
-			len++;
+		len = ALIGN(len, 4);
 		len += 8;
 	}
 
+	if (status->vendor_radiotap_len) {
+		if (WARN_ON_ONCE(status->vendor_radiotap_align == 0))
+			status->vendor_radiotap_align = 1;
+		/* align standard part of vendor namespace */
+		len = ALIGN(len, 2);
+		/* allocate standard part of vendor namespace */
+		len += 6;
+		/* align vendor-defined part */
+		len = ALIGN(len, status->vendor_radiotap_align);
+		/* vendor-defined part is already in skb */
+	}
+
 	return len;
 }
 
@@ -132,14 +153,25 @@ ieee80211_add_rx_radiotap_header(struct ieee80211_local *local,
 			    (1 << IEEE80211_RADIOTAP_CHANNEL) |
 			    (1 << IEEE80211_RADIOTAP_ANTENNA) |
 			    (1 << IEEE80211_RADIOTAP_RX_FLAGS));
-	rthdr->it_len = cpu_to_le16(rtap_len);
+	rthdr->it_len = cpu_to_le16(rtap_len + status->vendor_radiotap_len);
 
 	pos = (unsigned char *)(rthdr + 1);
 
+	if (status->vendor_radiotap_len) {
+		rthdr->it_present |=
+			cpu_to_le32(BIT(IEEE80211_RADIOTAP_VENDOR_NAMESPACE)) |
+			cpu_to_le32(BIT(IEEE80211_RADIOTAP_EXT));
+		put_unaligned_le32(status->vendor_radiotap_bitmap, pos);
+		pos += 4;
+	}
+
 	/* the order of the following fields is important */
 
 	/* IEEE80211_RADIOTAP_TSFT */
 	if (ieee80211_have_rx_timestamp(status)) {
+		/* padding */
+		while ((pos - (u8 *)rthdr) & 7)
+			*pos++ = 0;
 		put_unaligned_le64(
 			ieee80211_calculate_rx_timestamp(local, status,
 							 mpdulen, 0),
@@ -211,7 +243,7 @@ ieee80211_add_rx_radiotap_header(struct ieee80211_local *local,
 	/* IEEE80211_RADIOTAP_RX_FLAGS */
 	/* ensure 2 byte alignment for the 2 byte field as required */
 	if ((pos - (u8 *)rthdr) & 1)
-		pos++;
+		*pos++ = 0;
 	if (status->flag & RX_FLAG_FAILED_PLCP_CRC)
 		rx_flags |= IEEE80211_RADIOTAP_F_RX_BADPLCP;
 	put_unaligned_le16(rx_flags, pos);
@@ -261,6 +293,21 @@ ieee80211_add_rx_radiotap_header(struct ieee80211_local *local,
 			*pos++ = 0;
 		*pos++ = 0;
 	}
+
+	if (status->vendor_radiotap_len) {
+		/* ensure 2 byte alignment for the vendor field as required */
+		if ((pos - (u8 *)rthdr) & 1)
+			*pos++ = 0;
+		*pos++ = status->vendor_radiotap_oui[0];
+		*pos++ = status->vendor_radiotap_oui[1];
+		*pos++ = status->vendor_radiotap_oui[2];
+		*pos++ = status->vendor_radiotap_subns;
+		put_unaligned_le16(status->vendor_radiotap_len, pos);
+		pos += 2;
+		/* align the actual payload as requested */
+		while ((pos - (u8 *)rthdr) & (status->vendor_radiotap_align - 1))
+			*pos++ = 0;
+	}
 }
 
 /*
@@ -289,7 +336,7 @@ ieee80211_rx_monitor(struct ieee80211_local *local, struct sk_buff *origskb,
 	 */
 
 	/* room for the radiotap header based on driver features */
-	needed_headroom = ieee80211_rx_radiotap_len(local, status);
+	needed_headroom = ieee80211_rx_radiotap_space(local, status);
 
 	if (local->hw.flags & IEEE80211_HW_RX_INCLUDES_FCS)
 		present_fcs_len = FCS_LEN;
@@ -2593,7 +2640,7 @@ static void ieee80211_rx_cooked_monitor(struct ieee80211_rx_data *rx,
 		goto out_free_skb;
 
 	/* room for the radiotap header based on driver features */
-	needed_headroom = ieee80211_rx_radiotap_len(local, status);
+	needed_headroom = ieee80211_rx_radiotap_space(local, status);
 
 	if (skb_headroom(skb) < needed_headroom &&
 	    pskb_expand_head(skb, needed_headroom, 0, GFP_ATOMIC))