mac80211: Add cooked monitor mode support

This adds "cooked" monitor mode to mac80211. A monitor interface
in "cooked" mode will see all frames that mac80211 has not used
internally.

Signed-off-by: Michael Wu <flamingice@sourmilk.net>
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

3 files changed, 126 insertions, 31 deletions

diff --git a/net/mac80211/ieee80211.c b/net/mac80211/ieee80211.c
index 78fd91895c80..91f06c3f4a7c 100644
--- a/net/mac80211/ieee80211.c
+++ b/net/mac80211/ieee80211.c
@@ -239,6 +239,11 @@ static int ieee80211_open(struct net_device *dev)
                 /* no need to tell driver */
                 break;
         case IEEE80211_IF_TYPE_MNTR:
+                if (sdata->u.mntr_flags & MONITOR_FLAG_COOK_FRAMES) {
+                        local->cooked_mntrs++;
+                        break;
+                }
+
                 /* must be before the call to ieee80211_configure_filter */
                 local->monitors++;
                 if (local->monitors == 1)
@@ -370,6 +375,11 @@ static int ieee80211_stop(struct net_device *dev)
                 /* no need to tell driver */
                 break;
         case IEEE80211_IF_TYPE_MNTR:
+                if (sdata->u.mntr_flags & MONITOR_FLAG_COOK_FRAMES) {
+                        local->cooked_mntrs--;
+                        break;
+                }
+
                 local->monitors--;
                 if (local->monitors == 0)
                         local->hw.conf.flags &= ~IEEE80211_CONF_RADIOTAP;
@@ -1177,7 +1187,7 @@ void ieee80211_tx_status(struct ieee80211_hw *hw, struct sk_buff *skb,
         u16 frag, type;
         struct ieee80211_tx_status_rtap_hdr *rthdr;
         struct ieee80211_sub_if_data *sdata;
-        int monitors;
+        struct net_device *prev_dev = NULL;
 
         if (!status) {
                 printk(KERN_ERR
@@ -1290,7 +1300,11 @@ void ieee80211_tx_status(struct ieee80211_hw *hw, struct sk_buff *skb,
         /* this was a transmitted frame, but now we want to reuse it */
         skb_orphan(skb);
 
-        if (!local->monitors) {
+        /*
+         * This is a bit racy but we can avoid a lot of work
+         * with this test...
+         */
+        if (!local->monitors && !local->cooked_mntrs) {
                 dev_kfree_skb(skb);
                 return;
         }
@@ -1324,42 +1338,37 @@ void ieee80211_tx_status(struct ieee80211_hw *hw, struct sk_buff *skb,
 
         rthdr->data_retries = status->retry_count;
 
+        /* XXX: is this sufficient for BPF? */
+        skb_set_mac_header(skb, 0);
+        skb->ip_summed = CHECKSUM_UNNECESSARY;
+        skb->pkt_type = PACKET_OTHERHOST;
+        skb->protocol = htons(ETH_P_802_2);
+        memset(skb->cb, 0, sizeof(skb->cb));
+
         rcu_read_lock();
-        monitors = local->monitors;
         list_for_each_entry_rcu(sdata, &local->interfaces, list) {
-                /*
-                 * Using the monitors counter is possibly racy, but
-                 * if the value is wrong we simply either clone the skb
-                 * once too much or forget sending it to one monitor iface
-                 * The latter case isn't nice but fixing the race is much
-                 * more complicated.
-                 */
-                if (!monitors || !skb)
-                        goto out;
-
                 if (sdata->vif.type == IEEE80211_IF_TYPE_MNTR) {
                         if (!netif_running(sdata->dev))
                                 continue;
-                        monitors--;
-                        if (monitors)
+
+                        if (prev_dev) {
                                 skb2 = skb_clone(skb, GFP_ATOMIC);
-                        else
-                                skb2 = NULL;
-                        skb->dev = sdata->dev;
-                        /* XXX: is this sufficient for BPF? */
-                        skb_set_mac_header(skb, 0);
-                        skb->ip_summed = CHECKSUM_UNNECESSARY;
-                        skb->pkt_type = PACKET_OTHERHOST;
-                        skb->protocol = htons(ETH_P_802_2);
-                        memset(skb->cb, 0, sizeof(skb->cb));
-                        netif_rx(skb);
-                        skb = skb2;
+                                if (skb2) {
+                                        skb2->dev = prev_dev;
+                                        netif_rx(skb2);
+                                }
+                        }
+
+                        prev_dev = sdata->dev;
                 }
         }
- out:
+        if (prev_dev) {
+                skb->dev = prev_dev;
+                netif_rx(skb);
+                skb = NULL;
+        }
         rcu_read_unlock();
-        if (skb)
-                dev_kfree_skb(skb);
+        dev_kfree_skb(skb);
 }
 EXPORT_SYMBOL(ieee80211_tx_status);
 
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 1129a4299de7..1b4a4497030d 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -131,6 +131,7 @@ typedef unsigned __bitwise__ ieee80211_rx_result;
 #define IEEE80211_TXRXD_RXRA_MATCH              BIT(5)
 #define IEEE80211_TXRXD_TX_INJECTED             BIT(6)
 #define IEEE80211_TXRXD_RX_AMSDU                BIT(7)
+#define IEEE80211_TXRXD_RX_CMNTR_REPORTED       BIT(8)
 struct ieee80211_txrx_data {
         struct sk_buff *skb;
         struct net_device *dev;
@@ -419,7 +420,7 @@ struct ieee80211_local {
 
         struct net_device *mdev; /* wmaster# - "master" 802.11 device */
         int open_count;
-        int monitors;
+        int monitors, cooked_mntrs;
         /* number of interfaces with corresponding FIF_ flags */
         int fif_fcsfail, fif_plcpfail, fif_control, fif_other_bss;
         unsigned int filter_flags; /* FIF_* */
diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 3a3112f17832..b1fc112152c9 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -223,6 +223,9 @@ ieee80211_rx_monitor(struct ieee80211_local *local, struct sk_buff *origskb,
                 if (sdata->vif.type != IEEE80211_IF_TYPE_MNTR)
                         continue;
 
+                if (sdata->u.mntr_flags & MONITOR_FLAG_COOK_FRAMES)
+                        continue;
+
                 if (prev_dev) {
                         skb2 = skb_clone(skb, GFP_ATOMIC);
                         if (skb2) {
@@ -1520,6 +1523,86 @@ static void ieee80211_rx_michael_mic_report(struct net_device *dev,
         rx->skb = NULL;
 }
 
+static void ieee80211_rx_cooked_monitor(struct ieee80211_txrx_data *rx)
+{
+        struct ieee80211_sub_if_data *sdata;
+        struct ieee80211_local *local = rx->local;
+        struct ieee80211_rtap_hdr {
+                struct ieee80211_radiotap_header hdr;
+                u8 flags;
+                u8 rate;
+                __le16 chan_freq;
+                __le16 chan_flags;
+        } __attribute__ ((packed)) *rthdr;
+        struct sk_buff *skb = rx->skb, *skb2;
+        struct net_device *prev_dev = NULL;
+        struct ieee80211_rx_status *status = rx->u.rx.status;
+
+        if (rx->flags & IEEE80211_TXRXD_RX_CMNTR_REPORTED)
+                goto out_free_skb;
+
+        if (skb_headroom(skb) < sizeof(*rthdr) &&
+            pskb_expand_head(skb, sizeof(*rthdr), 0, GFP_ATOMIC))
+                goto out_free_skb;
+
+        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 =
+                cpu_to_le32((1 << IEEE80211_RADIOTAP_FLAGS) |
+                            (1 << IEEE80211_RADIOTAP_RATE) |
+                            (1 << IEEE80211_RADIOTAP_CHANNEL));
+
+        rthdr->rate = rx->u.rx.rate->bitrate / 5;
+        rthdr->chan_freq = cpu_to_le16(status->freq);
+
+        if (status->band == IEEE80211_BAND_5GHZ)
+                rthdr->chan_flags = cpu_to_le16(IEEE80211_CHAN_OFDM |
+                                                IEEE80211_CHAN_5GHZ);
+        else
+                rthdr->chan_flags = cpu_to_le16(IEEE80211_CHAN_DYN |
+                                                IEEE80211_CHAN_2GHZ);
+
+        skb_set_mac_header(skb, 0);
+        skb->ip_summed = CHECKSUM_UNNECESSARY;
+        skb->pkt_type = PACKET_OTHERHOST;
+        skb->protocol = htons(ETH_P_802_2);
+
+        list_for_each_entry_rcu(sdata, &local->interfaces, list) {
+                if (!netif_running(sdata->dev))
+                        continue;
+
+                if (sdata->vif.type != IEEE80211_IF_TYPE_MNTR ||
+                    !(sdata->u.mntr_flags & MONITOR_FLAG_COOK_FRAMES))
+                        continue;
+
+                if (prev_dev) {
+                        skb2 = skb_clone(skb, GFP_ATOMIC);
+                        if (skb2) {
+                                skb2->dev = prev_dev;
+                                netif_rx(skb2);
+                        }
+                }
+
+                prev_dev = sdata->dev;
+                sdata->dev->stats.rx_packets++;
+                sdata->dev->stats.rx_bytes += skb->len;
+        }
+
+        if (prev_dev) {
+                skb->dev = prev_dev;
+                netif_rx(skb);
+                skb = NULL;
+        } else
+                goto out_free_skb;
+
+        rx->flags |= IEEE80211_TXRXD_RX_CMNTR_REPORTED;
+        return;
+
+ out_free_skb:
+        dev_kfree_skb(skb);
+}
+
 typedef ieee80211_rx_result (*ieee80211_rx_handler)(struct ieee80211_txrx_data *);
 static ieee80211_rx_handler ieee80211_rx_handlers[] =
 {
@@ -1574,9 +1657,11 @@ static void ieee80211_invoke_rx_handlers(struct ieee80211_sub_if_data *sdata,
         }
 
         switch (res) {
+        case RX_CONTINUE:
         case RX_DROP_MONITOR:
+                ieee80211_rx_cooked_monitor(rx);
+                break;
         case RX_DROP_UNUSABLE:
-        case RX_CONTINUE:
                 dev_kfree_skb(rx->skb);
                 break;
         }