cfg80211/mac80211: allow registering for and sending action frames

This implements a new command to register for action frames
that userspace wants to handle instead of the in-kernel
rejection. It is then responsible for rejecting ones that
it decided not to handle. There is no unregistration, but
the socket can be closed for that.

Frames that are not registered for will not be forwarded
to userspace and will be rejected by the kernel, the
cfg80211 API helps implementing that.

Additionally, this patch adds a new command that allows
doing action frame transmission from userspace. It can be
used either to exchange action frames on the current
operational channel (e.g., with the AP with which we are
currently associated) or to exchange off-channel Public
Action frames with the remain-on-channel command.

Signed-off-by: Jouni Malinen <jouni.malinen@atheros.com>
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 31 insertions, 11 deletions

diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index a177472adc13..a6080d8d72bb 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -1856,28 +1856,25 @@ ieee80211_rx_h_action(struct ieee80211_rx_data *rx)
         struct ieee80211_sub_if_data *sdata = rx->sdata;
         struct ieee80211_mgmt *mgmt = (struct ieee80211_mgmt *) rx->skb->data;
         struct sk_buff *nskb;
+        struct ieee80211_rx_status *status;
         int len = rx->skb->len;
 
         if (!ieee80211_is_action(mgmt->frame_control))
                 return RX_CONTINUE;
 
-        if (!rx->sta)
+        /* drop too small frames */
+        if (len < IEEE80211_MIN_ACTION_SIZE)
                 return RX_DROP_UNUSABLE;
 
-        if (!(rx->flags & IEEE80211_RX_RA_MATCH))
+        if (!rx->sta && mgmt->u.action.category != WLAN_CATEGORY_PUBLIC)
                 return RX_DROP_UNUSABLE;
 
-        if (ieee80211_drop_unencrypted(rx, mgmt->frame_control))
+        if (!(rx->flags & IEEE80211_RX_RA_MATCH))
                 return RX_DROP_UNUSABLE;
 
-        /* drop too small frames */
-        if (len < IEEE80211_MIN_ACTION_SIZE)
+        if (ieee80211_drop_unencrypted(rx, mgmt->frame_control))
                 return RX_DROP_UNUSABLE;
 
-        /* return action frames that have *only* category */
-        if (len < IEEE80211_MIN_ACTION_SIZE + 1)
-                goto return_frame;
-
         switch (mgmt->u.action.category) {
         case WLAN_CATEGORY_BACK:
                 /*
@@ -1891,6 +1888,10 @@ ieee80211_rx_h_action(struct ieee80211_rx_data *rx)
                     sdata->vif.type != NL80211_IFTYPE_AP)
                         break;
 
+                /* verify action_code is present */
+                if (len < IEEE80211_MIN_ACTION_SIZE + 1)
+                        break;
+
                 switch (mgmt->u.action.u.addba_req.action_code) {
                 case WLAN_ACTION_ADDBA_REQ:
                         if (len < (IEEE80211_MIN_ACTION_SIZE +
@@ -1919,6 +1920,10 @@ ieee80211_rx_h_action(struct ieee80211_rx_data *rx)
                 if (sdata->vif.type != NL80211_IFTYPE_STATION)
                         break;
 
+                /* verify action_code is present */
+                if (len < IEEE80211_MIN_ACTION_SIZE + 1)
+                        break;
+
                 switch (mgmt->u.action.u.measurement.action_code) {
                 case WLAN_ACTION_SPCT_MSR_REQ:
                         if (len < (IEEE80211_MIN_ACTION_SIZE +
@@ -1954,7 +1959,7 @@ ieee80211_rx_h_action(struct ieee80211_rx_data *rx)
                 }
                 break;
         }
- return_frame:
+
         /*
          * For AP mode, hostapd is responsible for handling any action
          * frames that we didn't handle, including returning unknown
@@ -1966,6 +1971,20 @@ ieee80211_rx_h_action(struct ieee80211_rx_data *rx)
             sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
                 return RX_DROP_MONITOR;
 
+        /*
+         * Getting here means the kernel doesn't know how to handle
+         * it, but maybe userspace does ... include returned frames
+         * so userspace can register for those to know whether ones
+         * it transmitted were processed or returned.
+         */
+        status = IEEE80211_SKB_RXCB(rx->skb);
+
+        if (sdata->vif.type == NL80211_IFTYPE_STATION &&
+            cfg80211_rx_action(rx->sdata->dev, status->freq,
+                               rx->skb->data, rx->skb->len,
+                               GFP_ATOMIC))
+                goto handled;
+
         /* do not return rejected action frames */
         if (mgmt->u.action.category & 0x80)
                 return RX_DROP_UNUSABLE;
@@ -1985,7 +2004,8 @@ ieee80211_rx_h_action(struct ieee80211_rx_data *rx)
         }
 
  handled:
-        rx->sta->rx_packets++;
+        if (rx->sta)
+                rx->sta->rx_packets++;
         dev_kfree_skb(rx->skb);
         return RX_QUEUED;
 }