mac80211: add back support for radiotap vendor namespace data

Radiotap vendor namespace data might still be useful, but we
reverted it because it used too much space in the RX status.
Put it back, but address the space problem by using a single
bit only and putting everything else into the skb->data.

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

1 files changed, 82 insertions, 18 deletions

diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index bc63aa0c5401..f57af5c7c12a 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -39,7 +39,8 @@
  * only useful for monitoring.
  */
 static struct sk_buff *remove_monitor_info(struct ieee80211_local *local,
-                                           struct sk_buff *skb)
+                                           struct sk_buff *skb,
+                                           unsigned int rtap_vendor_space)
 {
         if (local->hw.flags & IEEE80211_HW_RX_INCLUDES_FCS) {
                 if (likely(skb->len > FCS_LEN))
@@ -52,20 +53,25 @@ static struct sk_buff *remove_monitor_info(struct ieee80211_local *local,
                 }
         }
 
+        __pskb_pull(skb, rtap_vendor_space);
+
         return skb;
 }
 
-static inline bool should_drop_frame(struct sk_buff *skb, int present_fcs_len)
+static inline bool should_drop_frame(struct sk_buff *skb, int present_fcs_len,
+                                     unsigned int rtap_vendor_space)
 {
         struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
-        struct ieee80211_hdr *hdr = (void *)skb->data;
+        struct ieee80211_hdr *hdr;
+
+        hdr = (void *)(skb->data + rtap_vendor_space);
 
         if (status->flag & (RX_FLAG_FAILED_FCS_CRC |
                             RX_FLAG_FAILED_PLCP_CRC |
                             RX_FLAG_AMPDU_IS_ZEROLEN))
                 return true;
 
-        if (unlikely(skb->len < 16 + present_fcs_len))
+        if (unlikely(skb->len < 16 + present_fcs_len + rtap_vendor_space))
                 return true;
 
         if (ieee80211_is_ctl(hdr->frame_control) &&
@@ -77,8 +83,9 @@ static inline bool should_drop_frame(struct sk_buff *skb, int present_fcs_len)
 }
 
 static int
-ieee80211_rx_radiotap_space(struct ieee80211_local *local,
-                            struct ieee80211_rx_status *status)
+ieee80211_rx_radiotap_hdrlen(struct ieee80211_local *local,
+                             struct ieee80211_rx_status *status,
+                             struct sk_buff *skb)
 {
         int len;
 
@@ -121,6 +128,21 @@ ieee80211_rx_radiotap_space(struct ieee80211_local *local,
                 len += 2 * hweight8(status->chains);
         }
 
+        if (status->flag & RX_FLAG_RADIOTAP_VENDOR_DATA) {
+                struct ieee80211_vendor_radiotap *rtap = (void *)skb->data;
+
+                /* vendor presence bitmap */
+                len += 4;
+                /* alignment for fixed 6-byte vendor data header */
+                len = ALIGN(len, 2);
+                /* vendor data header */
+                len += 6;
+                if (WARN_ON(rtap->align == 0))
+                        rtap->align = 1;
+                len = ALIGN(len, rtap->align);
+                len += rtap->len + rtap->pad;
+        }
+
         return len;
 }
 
@@ -144,13 +166,20 @@ ieee80211_add_rx_radiotap_header(struct ieee80211_local *local,
         u16 channel_flags = 0;
         int mpdulen, chain;
         unsigned long chains = status->chains;
+        struct ieee80211_vendor_radiotap rtap = {};
+
+        if (status->flag & RX_FLAG_RADIOTAP_VENDOR_DATA) {
+                rtap = *(struct ieee80211_vendor_radiotap *)skb->data;
+                /* rtap.len and rtap.pad are undone immediately */
+                skb_pull(skb, sizeof(rtap) + rtap.len + rtap.pad);
+        }
 
         mpdulen = skb->len;
         if (!(has_fcs && (local->hw.flags & IEEE80211_HW_RX_INCLUDES_FCS)))
                 mpdulen += FCS_LEN;
 
         rthdr = (struct ieee80211_radiotap_header *)skb_push(skb, rtap_len);
-        memset(rthdr, 0, rtap_len);
+        memset(rthdr, 0, rtap_len - rtap.len - rtap.pad);
         it_present = &rthdr->it_present;
 
         /* radiotap header, set always present flags */
@@ -172,6 +201,14 @@ ieee80211_add_rx_radiotap_header(struct ieee80211_local *local,
                                  BIT(IEEE80211_RADIOTAP_DBM_ANTSIGNAL);
         }
 
+        if (status->flag & RX_FLAG_RADIOTAP_VENDOR_DATA) {
+                it_present_val |= BIT(IEEE80211_RADIOTAP_VENDOR_NAMESPACE) |
+                                  BIT(IEEE80211_RADIOTAP_EXT);
+                put_unaligned_le32(it_present_val, it_present);
+                it_present++;
+                it_present_val = rtap.present;
+        }
+
         put_unaligned_le32(it_present_val, it_present);
 
         pos = (void *)(it_present + 1);
@@ -366,6 +403,22 @@ ieee80211_add_rx_radiotap_header(struct ieee80211_local *local,
                 *pos++ = status->chain_signal[chain];
                 *pos++ = chain;
         }
+
+        if (status->flag & RX_FLAG_RADIOTAP_VENDOR_DATA) {
+                /* ensure 2 byte alignment for the vendor field as required */
+                if ((pos - (u8 *)rthdr) & 1)
+                        *pos++ = 0;
+                *pos++ = rtap.oui[0];
+                *pos++ = rtap.oui[1];
+                *pos++ = rtap.oui[2];
+                *pos++ = rtap.subns;
+                put_unaligned_le16(rtap.len, pos);
+                pos += 2;
+                /* align the actual payload as requested */
+                while ((pos - (u8 *)rthdr) & (rtap.align - 1))
+                        *pos++ = 0;
+                /* data (and possible padding) already follows */
+        }
 }
 
 /*
@@ -379,10 +432,17 @@ ieee80211_rx_monitor(struct ieee80211_local *local, struct sk_buff *origskb,
 {
         struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(origskb);
         struct ieee80211_sub_if_data *sdata;
-        int needed_headroom;
+        int rt_hdrlen, needed_headroom;
         struct sk_buff *skb, *skb2;
         struct net_device *prev_dev = NULL;
         int present_fcs_len = 0;
+        unsigned int rtap_vendor_space = 0;
+
+        if (unlikely(status->flag & RX_FLAG_RADIOTAP_VENDOR_DATA)) {
+                struct ieee80211_vendor_radiotap *rtap = (void *)origskb->data;
+
+                rtap_vendor_space = sizeof(*rtap) + rtap->len + rtap->pad;
+        }
 
         /*
          * First, we may need to make a copy of the skb because
@@ -396,25 +456,27 @@ ieee80211_rx_monitor(struct ieee80211_local *local, struct sk_buff *origskb,
         if (local->hw.flags & IEEE80211_HW_RX_INCLUDES_FCS)
                 present_fcs_len = FCS_LEN;
 
-        /* ensure hdr->frame_control is in skb head */
-        if (!pskb_may_pull(origskb, 2)) {
+        /* ensure hdr->frame_control and vendor radiotap data are in skb head */
+        if (!pskb_may_pull(origskb, 2 + rtap_vendor_space)) {
                 dev_kfree_skb(origskb);
                 return NULL;
         }
 
         if (!local->monitors) {
-                if (should_drop_frame(origskb, present_fcs_len)) {
+                if (should_drop_frame(origskb, present_fcs_len,
+                                      rtap_vendor_space)) {
                         dev_kfree_skb(origskb);
                         return NULL;
                 }
 
-                return remove_monitor_info(local, origskb);
+                return remove_monitor_info(local, origskb, rtap_vendor_space);
         }
 
         /* room for the radiotap header based on driver features */
-        needed_headroom = ieee80211_rx_radiotap_space(local, status);
+        rt_hdrlen = ieee80211_rx_radiotap_hdrlen(local, status, origskb);
+        needed_headroom = rt_hdrlen - rtap_vendor_space;
 
-        if (should_drop_frame(origskb, present_fcs_len)) {
+        if (should_drop_frame(origskb, present_fcs_len, rtap_vendor_space)) {
                 /* only need to expand headroom if necessary */
                 skb = origskb;
                 origskb = NULL;
@@ -438,15 +500,15 @@ ieee80211_rx_monitor(struct ieee80211_local *local, struct sk_buff *origskb,
                  */
                 skb = skb_copy_expand(origskb, needed_headroom, 0, GFP_ATOMIC);
 
-                origskb = remove_monitor_info(local, origskb);
+                origskb = remove_monitor_info(local, origskb,
+                                              rtap_vendor_space);
 
                 if (!skb)
                         return origskb;
         }
 
         /* prepend radiotap information */
-        ieee80211_add_rx_radiotap_header(local, skb, rate, needed_headroom,
-                                         true);
+        ieee80211_add_rx_radiotap_header(local, skb, rate, rt_hdrlen, true);
 
         skb_reset_mac_header(skb);
         skb->ip_summed = CHECKSUM_UNNECESSARY;
@@ -2892,8 +2954,10 @@ static void ieee80211_rx_cooked_monitor(struct ieee80211_rx_data *rx,
         if (!local->cooked_mntrs)
                 goto out_free_skb;
 
+        /* vendor data is long removed here */
+        status->flag &= ~RX_FLAG_RADIOTAP_VENDOR_DATA;
         /* room for the radiotap header based on driver features */
-        needed_headroom = ieee80211_rx_radiotap_space(local, status);
+        needed_headroom = ieee80211_rx_radiotap_hdrlen(local, status, skb);
 
         if (skb_headroom(skb) < needed_headroom &&
             pskb_expand_head(skb, needed_headroom, 0, GFP_ATOMIC))