mac80211: conditionally include timestamp in radiotap information

This makes mac80211 include the low-level MAC timestamp
in the radiotap header if the driver indicated (by a new
RX flag) that the timestamp is valid.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 32 insertions, 16 deletions

diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index c542fc1c983d..9cd59ecbcd67 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -79,8 +79,9 @@ ieee80211_rx_monitor(struct ieee80211_local *local, struct sk_buff *origskb,
         struct ieee80211_sub_if_data *sdata;
         struct ieee80211_rate *rate;
         int needed_headroom = 0;
-        struct ieee80211_rtap_hdr {
-                struct ieee80211_radiotap_header hdr;
+        struct ieee80211_radiotap_header *rthdr;
+        __le64 *rttsft = NULL;
+        struct ieee80211_rtap_fixed_data {
                 u8 flags;
                 u8 rate;
                 __le16 chan_freq;
@@ -88,7 +89,7 @@ ieee80211_rx_monitor(struct ieee80211_local *local, struct sk_buff *origskb,
                 u8 antsignal;
                 u8 padding_for_rxflags;
                 __le16 rx_flags;
-        } __attribute__ ((packed)) *rthdr;
+        } __attribute__ ((packed)) *rtfixed;
         struct sk_buff *skb, *skb2;
         struct net_device *prev_dev = NULL;
         int present_fcs_len = 0;
@@ -105,7 +106,8 @@ ieee80211_rx_monitor(struct ieee80211_local *local, struct sk_buff *origskb,
         if (status->flag & RX_FLAG_RADIOTAP)
                 rtap_len = ieee80211_get_radiotap_len(origskb->data);
         else
-                needed_headroom = sizeof(*rthdr);
+                /* room for radiotap header, always present fields and TSFT */
+                needed_headroom = sizeof(*rthdr) + sizeof(*rtfixed) + 8;
 
         if (local->hw.flags & IEEE80211_HW_RX_INCLUDES_FCS)
                 present_fcs_len = FCS_LEN;
@@ -133,7 +135,7 @@ ieee80211_rx_monitor(struct ieee80211_local *local, struct sk_buff *origskb,
                  * them allocate enough headroom to start with.
                  */
                 if (skb_headroom(skb) < needed_headroom &&
-                    pskb_expand_head(skb, sizeof(*rthdr), 0, GFP_ATOMIC)) {
+                    pskb_expand_head(skb, needed_headroom, 0, GFP_ATOMIC)) {
                         dev_kfree_skb(skb);
                         return NULL;
                 }
@@ -152,42 +154,56 @@ ieee80211_rx_monitor(struct ieee80211_local *local, struct sk_buff *origskb,
 
         /* if necessary, prepend radiotap information */
         if (!(status->flag & RX_FLAG_RADIOTAP)) {
+                rtfixed = (void *) skb_push(skb, sizeof(*rtfixed));
+                rtap_len = sizeof(*rthdr) + sizeof(*rtfixed);
+                if (status->flag & RX_FLAG_TSFT) {
+                        rttsft = (void *) skb_push(skb, sizeof(*rttsft));
+                        rtap_len += 8;
+                }
                 rthdr = (void *) skb_push(skb, sizeof(*rthdr));
                 memset(rthdr, 0, sizeof(*rthdr));
-                rthdr->hdr.it_len = cpu_to_le16(sizeof(*rthdr));
-                rthdr->hdr.it_present =
+                memset(rtfixed, 0, sizeof(*rtfixed));
+                rthdr->it_present =
                         cpu_to_le32((1 << IEEE80211_RADIOTAP_FLAGS) |
                                     (1 << IEEE80211_RADIOTAP_RATE) |
                                     (1 << IEEE80211_RADIOTAP_CHANNEL) |
                                     (1 << IEEE80211_RADIOTAP_DB_ANTSIGNAL) |
                                     (1 << IEEE80211_RADIOTAP_RX_FLAGS));
-                rthdr->flags = local->hw.flags & IEEE80211_HW_RX_INCLUDES_FCS ?
-                               IEEE80211_RADIOTAP_F_FCS : 0;
+                rtfixed->flags = 0;
+                if (local->hw.flags & IEEE80211_HW_RX_INCLUDES_FCS)
+                        rtfixed->flags |= IEEE80211_RADIOTAP_F_FCS;
+
+                if (rttsft) {
+                        *rttsft = cpu_to_le64(status->mactime);
+                        rthdr->it_present |=
+                                cpu_to_le32(1 << IEEE80211_RADIOTAP_TSFT);
+                }
 
                 /* FIXME: when radiotap gets a 'bad PLCP' flag use it here */
-                rthdr->rx_flags = 0;
+                rtfixed->rx_flags = 0;
                 if (status->flag &
                     (RX_FLAG_FAILED_FCS_CRC | RX_FLAG_FAILED_PLCP_CRC))
-                        rthdr->rx_flags |=
+                        rtfixed->rx_flags |=
                                 cpu_to_le16(IEEE80211_RADIOTAP_F_RX_BADFCS);
 
                 rate = ieee80211_get_rate(local, status->phymode,
                                           status->rate);
                 if (rate)
-                        rthdr->rate = rate->rate / 5;
+                        rtfixed->rate = rate->rate / 5;
 
-                rthdr->chan_freq = cpu_to_le16(status->freq);
+                rtfixed->chan_freq = cpu_to_le16(status->freq);
 
                 if (status->phymode == MODE_IEEE80211A)
-                        rthdr->chan_flags =
+                        rtfixed->chan_flags =
                                 cpu_to_le16(IEEE80211_CHAN_OFDM |
                                             IEEE80211_CHAN_5GHZ);
                 else
-                        rthdr->chan_flags =
+                        rtfixed->chan_flags =
                                 cpu_to_le16(IEEE80211_CHAN_DYN |
                                             IEEE80211_CHAN_2GHZ);
 
-                rthdr->antsignal = status->ssi;
+                rtfixed->antsignal = status->ssi;
+                rthdr->it_len = cpu_to_le16(rtap_len);
         }
 
         skb_set_mac_header(skb, 0);