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, 32 insertions, 1 deletions

diff --git a/drivers/net/wireless/mac80211_hwsim.c b/drivers/net/wireless/mac80211_hwsim.c
index ce522aa93af7..c242f5a9b8bc 100644
--- a/drivers/net/wireless/mac80211_hwsim.c
+++ b/drivers/net/wireless/mac80211_hwsim.c
@@ -751,7 +751,11 @@ static bool mac80211_hwsim_tx_frame_no_nl(struct ieee80211_hw *hw,
                                 continue;
                 }
 
-                nskb = skb_copy(skb, GFP_ATOMIC);
+                /*
+                 * reserve some space for our vendor and the normal
+                 * radiotap header, since we're copying anyway
+                 */
+                nskb = skb_copy_expand(skb, 64, 0, GFP_ATOMIC);
                 if (nskb == NULL)
                         continue;
 
@@ -769,6 +773,33 @@ static bool mac80211_hwsim_tx_frame_no_nl(struct ieee80211_hw *hw,
                                 (data->tsf_offset - data2->tsf_offset) +
                                 24 * 8 * 10 / txrate->bitrate);
 
+#if 0
+                /*
+                 * Don't enable this code by default as the OUI 00:00:00
+                 * is registered to Xerox so we shouldn't use it here, it
+                 * might find its way into pcap files.
+                 * Note that this code requires the headroom in the SKB
+                 * that was allocated earlier.
+                 */
+                rx_status.vendor_radiotap_oui[0] = 0x00;
+                rx_status.vendor_radiotap_oui[1] = 0x00;
+                rx_status.vendor_radiotap_oui[2] = 0x00;
+                rx_status.vendor_radiotap_subns = 127;
+                /*
+                 * Radiotap vendor namespaces can (and should) also be
+                 * split into fields by using the standard radiotap
+                 * presence bitmap mechanism. Use just BIT(0) here for
+                 * the presence bitmap.
+                 */
+                rx_status.vendor_radiotap_bitmap = BIT(0);
+                /* We have 8 bytes of (dummy) data */
+                rx_status.vendor_radiotap_len = 8;
+                /* For testing, also require it to be aligned */
+                rx_status.vendor_radiotap_align = 8;
+                /* push the data */
+                memcpy(skb_push(nskb, 8), "ABCDEFGH", 8);
+#endif
+
                 memcpy(IEEE80211_SKB_RXCB(nskb), &rx_status, sizeof(rx_status));
                 ieee80211_rx_irqsafe(data2->hw, nskb);
         }