[PATCH 1/3] cfg80211: support an active monitor interface flag

[PATCH 1/3] cfg80211: support an active monitor interface flag

[Felix Fietkau]

An active monitor interface is one that is used for communication (via
injection). It is expected to ACK incoming unicast packets. This is
useful for running various 802.11 testing utilities that associate to an
AP via injection and manage the state in user space.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
---
 include/net/cfg80211.h       | 1 +
 include/uapi/linux/nl80211.h | 3 +++
 net/wireless/nl80211.c       | 1 +
 3 files changed, 5 insertions(+)

diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index 26b5b69..489821f 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -954,6 +954,7 @@ enum monitor_flags {
 	MONITOR_FLAG_CONTROL		= 1<<NL80211_MNTR_FLAG_CONTROL,
 	MONITOR_FLAG_OTHER_BSS		= 1<<NL80211_MNTR_FLAG_OTHER_BSS,
 	MONITOR_FLAG_COOK_FRAMES	= 1<<NL80211_MNTR_FLAG_COOK_FRAMES,
+	MONITOR_FLAG_ACTIVE		= 1<<NL80211_MNTR_FLAG_ACTIVE,
 };
 
 /**
diff --git a/include/uapi/linux/nl80211.h b/include/uapi/linux/nl80211.h
index d1e48b5..d607848 100644
--- a/include/uapi/linux/nl80211.h
+++ b/include/uapi/linux/nl80211.h
@@ -2413,6 +2413,8 @@ enum nl80211_survey_info {
  * @NL80211_MNTR_FLAG_OTHER_BSS: disable BSSID filtering
  * @NL80211_MNTR_FLAG_COOK_FRAMES: report frames after processing.
  *	overrides all other flags.
+ * @NL80211_MNTR_FLAG_ACTIVE: use the configured MAC address
+ *	and ACK incoming unicast packets.
  *
  * @__NL80211_MNTR_FLAG_AFTER_LAST: internal use
  * @NL80211_MNTR_FLAG_MAX: highest possible monitor flag
@@ -2424,6 +2426,7 @@ enum nl80211_mntr_flags {
 	NL80211_MNTR_FLAG_CONTROL,
 	NL80211_MNTR_FLAG_OTHER_BSS,
 	NL80211_MNTR_FLAG_COOK_FRAMES,
+	NL80211_MNTR_FLAG_ACTIVE,
 
 	/* keep last */
 	__NL80211_MNTR_FLAG_AFTER_LAST,
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index dfdb5e6..500a6c5 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -2279,6 +2279,7 @@ static const struct nla_policy mntr_flags_policy[NL80211_MNTR_FLAG_MAX + 1] = {
 	[NL80211_MNTR_FLAG_CONTROL] = { .type = NLA_FLAG },
 	[NL80211_MNTR_FLAG_OTHER_BSS] = { .type = NLA_FLAG },
 	[NL80211_MNTR_FLAG_COOK_FRAMES] = { .type = NLA_FLAG },
+	[NL80211_MNTR_FLAG_ACTIVE] = { .type = NLA_FLAG },
 };
 
 static int parse_monitor_flags(struct nlattr *nla, u32 *mntrflags)
-- 
1.8.0.2

[PATCH 2/3] mac80211: support active monitor interfaces

[Felix Fietkau]

Support them only if the driver advertises support for them via
IEEE80211_HW_SUPPORTS_ACTIVE_MONITOR. Unlike normal monitor interfaces,
they are added to the driver, along with their MAC address.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
---
 include/net/mac80211.h     |  5 +++++
 net/mac80211/cfg.c         | 11 +++++++----
 net/mac80211/driver-ops.h  |  3 ++-
 net/mac80211/ieee80211_i.h |  2 +-
 net/mac80211/iface.c       | 33 ++++++++++++++++++++++++++-------
 net/mac80211/util.c        |  6 ++++++
 6 files changed, 47 insertions(+), 13 deletions(-)

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 885898a..b80c5cd 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -1455,6 +1455,10 @@ struct ieee80211_tx_control {
  *
  * @IEEE80211_HW_TIMING_BEACON_ONLY: Use sync timing from beacon frames
  *	only, to allow getting TBTT of a DTIM beacon.
+ *
+ * @IEEE80211_HW_SUPPORTS_ACTIVE_MONITOR: Device supports an active monitor
+ *	interface that responds to unicast packets directed at its MAC
+ *	address.
  */
 enum ieee80211_hw_flags {
 	IEEE80211_HW_HAS_RATE_CONTROL			= 1<<0,
@@ -1484,6 +1488,7 @@ enum ieee80211_hw_flags {
 	IEEE80211_HW_SUPPORTS_RC_TABLE			= 1<<24,
 	IEEE80211_HW_P2P_DEV_ADDR_FOR_INTF		= 1<<25,
 	IEEE80211_HW_TIMING_BEACON_ONLY			= 1<<26,
+	IEEE80211_HW_SUPPORTS_ACTIVE_MONITOR		= 1<<27,
 };
 
 /**
diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index 1a89c80..7f73859 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -73,16 +73,19 @@ static int ieee80211_change_iface(struct wiphy *wiphy,
 		struct ieee80211_local *local = sdata->local;
 
 		if (ieee80211_sdata_running(sdata)) {
+			u32 mask = MONITOR_FLAG_COOK_FRAMES |
+				   MONITOR_FLAG_ACTIVE;
+
 			/*
-			 * Prohibit MONITOR_FLAG_COOK_FRAMES to be
-			 * changed while the interface is up.
+			 * Prohibit MONITOR_FLAG_COOK_FRAMES and
+			 * MONITOR_FLAG_ACTIVE to be changed while the
+			 * interface is up.
 			 * Else we would need to add a lot of cruft
 			 * to update everything:
 			 *	cooked_mntrs, monitor and all fif_* counters
 			 *	reconfigure hardware
 			 */
-			if ((*flags & MONITOR_FLAG_COOK_FRAMES) !=
-			    (sdata->u.mntr_flags & MONITOR_FLAG_COOK_FRAMES))
+			if ((*flags & mask) != (sdata->u.mntr_flags & mask))
 				return -EBUSY;
 
 			ieee80211_adjust_monitor_flags(sdata, -1);
diff --git a/net/mac80211/driver-ops.h b/net/mac80211/driver-ops.h
index 169664c..5844f68 100644
--- a/net/mac80211/driver-ops.h
+++ b/net/mac80211/driver-ops.h
@@ -146,7 +146,8 @@ static inline int drv_add_interface(struct ieee80211_local *local,
 
 	if (WARN_ON(sdata->vif.type == NL80211_IFTYPE_AP_VLAN ||
 		    (sdata->vif.type == NL80211_IFTYPE_MONITOR &&
-		     !(local->hw.flags & IEEE80211_HW_WANT_MONITOR_VIF))))
+		     !(local->hw.flags & IEEE80211_HW_WANT_MONITOR_VIF) &&
+			 !(sdata->u.mntr_flags & MONITOR_FLAG_ACTIVE))))
 		return -EINVAL;
 
 	trace_drv_add_interface(local, sdata);
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 44be28c..280170a 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -892,7 +892,7 @@ struct ieee80211_local {
 	spinlock_t queue_stop_reason_lock;
 
 	int open_count;
-	int monitors, cooked_mntrs;
+	int monitors, cooked_mntrs, active_mntrs;
 	/* number of interfaces with corresponding FIF_ flags */
 	int fif_fcsfail, fif_plcpfail, fif_control, fif_other_bss, fif_pspoll,
 	    fif_probe_req;
diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index 60f1ce5..234503f 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -209,9 +209,11 @@ static int ieee80211_change_mac(struct net_device *dev, void *addr)
 	if (ieee80211_sdata_running(sdata))
 		return -EBUSY;
 
-	ret = ieee80211_verify_mac(sdata->local, sa->sa_data);
-	if (ret)
-		return ret;
+	if (sdata->vif.type != NL80211_IFTYPE_MONITOR) {
+		ret = ieee80211_verify_mac(sdata->local, sa->sa_data);
+		if (ret)
+			return ret;
+	}
 
 	ret = eth_mac_addr(dev, sa);
 
@@ -479,9 +481,13 @@ int ieee80211_do_open(struct wireless_dev *wdev, bool coming_up)
 	case NL80211_IFTYPE_AP:
 		sdata->bss = &sdata->u.ap;
 		break;
+	case NL80211_IFTYPE_MONITOR:
+		if ((sdata->u.mntr_flags & MONITOR_FLAG_ACTIVE) &&
+		    !(local->hw.flags & IEEE80211_HW_SUPPORTS_ACTIVE_MONITOR))
+			return -EOPNOTSUPP;
+		break;
 	case NL80211_IFTYPE_MESH_POINT:
 	case NL80211_IFTYPE_STATION:
-	case NL80211_IFTYPE_MONITOR:
 	case NL80211_IFTYPE_ADHOC:
 	case NL80211_IFTYPE_P2P_DEVICE:
 		/* no special treatment */
@@ -538,7 +544,13 @@ int ieee80211_do_open(struct wireless_dev *wdev, bool coming_up)
 			break;
 		}
 
-		if (local->monitors == 0 && local->open_count == 0) {
+		if (sdata->u.mntr_flags & MONITOR_FLAG_ACTIVE) {
+			res = drv_add_interface(local, sdata);
+			if (res)
+				goto err_stop;
+
+			local->active_mntrs++;
+		} else if (local->monitors == 0 && local->open_count == 0) {
 			res = ieee80211_add_virtual_monitor(local);
 			if (res)
 				goto err_stop;
@@ -831,6 +843,9 @@ static void ieee80211_do_stop(struct ieee80211_sub_if_data *sdata,
 			break;
 		}
 
+		if (sdata->u.mntr_flags & MONITOR_FLAG_ACTIVE)
+			local->active_mntrs--;
+
 		local->monitors--;
 		if (local->monitors == 0) {
 			local->hw.conf.flags &= ~IEEE80211_CONF_MONITOR;
@@ -912,7 +927,11 @@ static void ieee80211_do_stop(struct ieee80211_sub_if_data *sdata,
 		mutex_lock(&local->mtx);
 		ieee80211_recalc_idle(local);
 		mutex_unlock(&local->mtx);
-		break;
+
+		if (!(sdata->u.mntr_flags & MONITOR_FLAG_ACTIVE))
+			break;
+
+		/* fall through */
 	default:
 		if (going_down)
 			drv_remove_interface(local, sdata);
@@ -1061,7 +1080,7 @@ static const struct net_device_ops ieee80211_monitorif_ops = {
 	.ndo_start_xmit		= ieee80211_monitor_start_xmit,
 	.ndo_set_rx_mode	= ieee80211_set_multicast_list,
 	.ndo_change_mtu 	= ieee80211_change_mtu,
-	.ndo_set_mac_address 	= eth_mac_addr,
+	.ndo_set_mac_address 	= ieee80211_change_mac,
 	.ndo_select_queue	= ieee80211_monitor_select_queue,
 };
 
diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index 27e0715..7cbe0db 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -560,6 +560,9 @@ void ieee80211_iterate_active_interfaces(
 	list_for_each_entry(sdata, &local->interfaces, list) {
 		switch (sdata->vif.type) {
 		case NL80211_IFTYPE_MONITOR:
+			if (!(sdata->u.mntr_flags & MONITOR_FLAG_ACTIVE))
+				continue;
+			break;
 		case NL80211_IFTYPE_AP_VLAN:
 			continue;
 		default:
@@ -598,6 +601,9 @@ void ieee80211_iterate_active_interfaces_atomic(
 	list_for_each_entry_rcu(sdata, &local->interfaces, list) {
 		switch (sdata->vif.type) {
 		case NL80211_IFTYPE_MONITOR:
+			if (!(sdata->u.mntr_flags & MONITOR_FLAG_ACTIVE))
+				continue;
+			break;
 		case NL80211_IFTYPE_AP_VLAN:
 			continue;
 		default:
-- 
1.8.0.2

Re: [PATCH 2/3] mac80211: support active monitor interfaces

[Johannes Berg]

On Sun, 2013-05-26 at 16:05 +0200, Felix Fietkau wrote:
> Support them only if the driver advertises support for them via
> IEEE80211_HW_SUPPORTS_ACTIVE_MONITOR. Unlike normal monitor interfaces,
> they are added to the driver, along with their MAC address.
> 
> Signed-off-by: Felix Fietkau <nbd@openwrt.org>
> ---
>  include/net/mac80211.h     |  5 +++++
>  net/mac80211/cfg.c         | 11 +++++++----
>  net/mac80211/driver-ops.h  |  3 ++-
>  net/mac80211/ieee80211_i.h |  2 +-
>  net/mac80211/iface.c       | 33 ++++++++++++++++++++++++++-------
>  net/mac80211/util.c        |  6 ++++++
>  6 files changed, 47 insertions(+), 13 deletions(-)
> 
> diff --git a/include/net/mac80211.h b/include/net/mac80211.h
> index 885898a..b80c5cd 100644
> --- a/include/net/mac80211.h
> +++ b/include/net/mac80211.h
> @@ -1455,6 +1455,10 @@ struct ieee80211_tx_control {
>   *
>   * @IEEE80211_HW_TIMING_BEACON_ONLY: Use sync timing from beacon frames
>   *	only, to allow getting TBTT of a DTIM beacon.
> + *
> + * @IEEE80211_HW_SUPPORTS_ACTIVE_MONITOR: Device supports an active monitor
> + *	interface that responds to unicast packets directed at its MAC
> + *	address.

... basically moving this to nl80211

johannes

Re: [PATCH 2/3] mac80211: support active monitor interfaces

[Johannes Berg]

On Sun, 2013-05-26 at 16:05 +0200, Felix Fietkau wrote:

>  	if (WARN_ON(sdata->vif.type == NL80211_IFTYPE_AP_VLAN ||
>  		    (sdata->vif.type == NL80211_IFTYPE_MONITOR &&
> -		     !(local->hw.flags & IEEE80211_HW_WANT_MONITOR_VIF))))
> +		     !(local->hw.flags & IEEE80211_HW_WANT_MONITOR_VIF) &&
> +			 !(sdata->u.mntr_flags & MONITOR_FLAG_ACTIVE))))
>  		return -EINVAL;

bad indentation

> +++ b/net/mac80211/iface.c
> @@ -209,9 +209,11 @@ static int ieee80211_change_mac(struct net_device *dev, void *addr)
>  	if (ieee80211_sdata_running(sdata))
>  		return -EBUSY;
>  
> -	ret = ieee80211_verify_mac(sdata->local, sa->sa_data);
> -	if (ret)
> -		return ret;
> +	if (sdata->vif.type != NL80211_IFTYPE_MONITOR) {
> +		ret = ieee80211_verify_mac(sdata->local, sa->sa_data);
> +		if (ret)
> +			return ret;
> +	}

I'm not convinced this makes sense, why would you want to have a monitor
with an invalid address? I'd rather not allow that, having e.g. a
multicast address that is ACK'ing frames would be very very strange.
 
> @@ -479,9 +481,13 @@ int ieee80211_do_open(struct wireless_dev *wdev, bool coming_up)
>  	case NL80211_IFTYPE_AP:
>  		sdata->bss = &sdata->u.ap;
>  		break;
> +	case NL80211_IFTYPE_MONITOR:
> +		if ((sdata->u.mntr_flags & MONITOR_FLAG_ACTIVE) &&
> +		    !(local->hw.flags & IEEE80211_HW_SUPPORTS_ACTIVE_MONITOR))
> +			return -EOPNOTSUPP;

How can you even get here? Shouldn't you just disallow setting the flag
unless it's supported?

> -		if (local->monitors == 0 && local->open_count == 0) {
> +		if (sdata->u.mntr_flags & MONITOR_FLAG_ACTIVE) {
> +			res = drv_add_interface(local, sdata);
> +			if (res)
> +				goto err_stop;
> +
> +			local->active_mntrs++;

Did I miss something, or don't you use the counter?

johannes

[PATCH 3/3] ath9k: advertise support for active monitor interfaces

[Felix Fietkau]

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
---
 drivers/net/wireless/ath/ath9k/init.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/ath/ath9k/init.c b/drivers/net/wireless/ath/ath9k/init.c
index c0aa4ff..86b14e8 100644
--- a/drivers/net/wireless/ath/ath9k/init.c
+++ b/drivers/net/wireless/ath/ath9k/init.c
@@ -764,7 +764,8 @@ void ath9k_set_hw_capab(struct ath_softc *sc, struct ieee80211_hw *hw)
 		IEEE80211_HW_PS_NULLFUNC_STACK |
 		IEEE80211_HW_SPECTRUM_MGMT |
 		IEEE80211_HW_REPORTS_TX_ACK_STATUS |
-		IEEE80211_HW_SUPPORTS_RC_TABLE;
+		IEEE80211_HW_SUPPORTS_RC_TABLE |
+		IEEE80211_HW_SUPPORTS_ACTIVE_MONITOR;
 
 	if (sc->sc_ah->caps.hw_caps & ATH9K_HW_CAP_HT)
 		 hw->flags |= IEEE80211_HW_AMPDU_AGGREGATION;
-- 
1.8.0.2

Re: [PATCH 1/3] cfg80211: support an active monitor interface flag

[Johannes Berg]

On Sun, 2013-05-26 at 16:05 +0200, Felix Fietkau wrote:
> An active monitor interface is one that is used for communication (via
> injection). It is expected to ACK incoming unicast packets. This is
> useful for running various 802.11 testing utilities that associate to an
> AP via injection and manage the state in user space.

I think it would be useful to make an nl80211 feature flag for this.

johannes