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>

include/linux/nl80211.h

@@ -3,7 +3,7 @@
 /*
  * 802.11 netlink interface public header
  *
- * Copyright 2006, 2007, 2008 Johannes Berg <johannes@sipsolutions.net>
+ * Copyright 2006-2010 Johannes Berg <johannes@sipsolutions.net>
  * Copyright 2008 Michael Wu <flamingice@sourmilk.net>
  * Copyright 2008 Luis Carlos Cobo <luisca@cozybit.com>
  * Copyright 2008 Michael Buesch <mb@bu3sch.de>
@@ -299,6 +299,31 @@
  *	rate selection. %NL80211_ATTR_IFINDEX is used to specify the interface
  *	and @NL80211_ATTR_TX_RATES the set of allowed rates.
  *
+ * @NL80211_CMD_REGISTER_ACTION: Register for receiving certain action frames
+ *	(via @NL80211_CMD_ACTION) for processing in userspace. This command
+ *	requires an interface index and a match attribute containing the first
+ *	few bytes of the frame that should match, e.g. a single byte for only
+ *	a category match or four bytes for vendor frames including the OUI.
+ *	The registration cannot be dropped, but is removed automatically
+ *	when the netlink socket is closed. Multiple registrations can be made.
+ * @NL80211_CMD_ACTION: Action frame TX request and RX notification. This
+ *	command is used both as a request to transmit an Action frame and as an
+ *	event indicating reception of an Action frame that was not processed in
+ *	kernel code, but is for us (i.e., which may need to be processed in a
+ *	user space application). %NL80211_ATTR_FRAME is used to specify the
+ *	frame contents (including header). %NL80211_ATTR_WIPHY_FREQ (and
+ *	optionally %NL80211_ATTR_WIPHY_CHANNEL_TYPE) is used to indicate on
+ *	which channel the frame is to be transmitted or was received. This
+ *	channel has to be the current channel (remain-on-channel or the
+ *	operational channel). When called, this operation returns a cookie
+ *	(%NL80211_ATTR_COOKIE) that will be included with the TX status event
+ *	pertaining to the TX request.
+ * @NL80211_CMD_ACTION_TX_STATUS: Report TX status of an Action frame
+ *	transmitted with %NL80211_CMD_ACTION. %NL80211_ATTR_COOKIE identifies
+ *	the TX command and %NL80211_ATTR_FRAME includes the contents of the
+ *	frame. %NL80211_ATTR_ACK flag is included if the recipient acknowledged
+ *	the frame.
+ *
  * @NL80211_CMD_MAX: highest used command number
  * @__NL80211_CMD_AFTER_LAST: internal use
  */
@@ -387,6 +412,10 @@ enum nl80211_commands {
 
 	NL80211_CMD_SET_TX_BITRATE_MASK,
 
+	NL80211_CMD_REGISTER_ACTION,
+	NL80211_CMD_ACTION,
+	NL80211_CMD_ACTION_TX_STATUS,
+
 	/* add new commands above here */
 
 	/* used to define NL80211_CMD_MAX below */
@@ -653,6 +682,12 @@ enum nl80211_commands {
  *	rates based on negotiated supported rates information. This attribute
  *	is used with %NL80211_CMD_SET_TX_BITRATE_MASK.
  *
+ * @NL80211_ATTR_FRAME_MATCH: A binary attribute which typically must contain
+ *	at least one byte, currently used with @NL80211_CMD_REGISTER_ACTION.
+ *
+ * @NL80211_ATTR_ACK: Flag attribute indicating that the frame was
+ *	acknowledged by the recipient.
+ *
  * @NL80211_ATTR_MAX: highest attribute number currently defined
  * @__NL80211_ATTR_AFTER_LAST: internal use
  */
@@ -798,6 +833,10 @@ enum nl80211_attrs {
 
 	NL80211_ATTR_TX_RATES,
 
+	NL80211_ATTR_FRAME_MATCH,
+
+	NL80211_ATTR_ACK,
+
 	/* add attributes here, update the policy in nl80211.c */
 
 	__NL80211_ATTR_AFTER_LAST,

include/net/cfg80211.h

@@ -3,7 +3,7 @@
 /*
  * 802.11 device and configuration interface
  *
- * Copyright 2006-2009	Johannes Berg <johannes@sipsolutions.net>
+ * Copyright 2006-2010	Johannes Berg <johannes@sipsolutions.net>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
@@ -998,6 +998,7 @@ struct cfg80211_pmksa {
  * @cancel_remain_on_channel: Cancel an on-going remain-on-channel operation.
  *	This allows the operation to be terminated prior to timeout based on
  *	the duration value.
+ * @action: Transmit an action frame
  *
  * @testmode_cmd: run a test mode command
  *
@@ -1144,6 +1145,11 @@ struct cfg80211_ops {
 					    struct net_device *dev,
 					    u64 cookie);
 
+	int	(*action)(struct wiphy *wiphy, struct net_device *dev,
+			  struct ieee80211_channel *chan,
+			  enum nl80211_channel_type channel_type,
+			  const u8 *buf, size_t len, u64 *cookie);
+
 	/* some temporary stuff to finish wext */
 	int	(*set_power_mgmt)(struct wiphy *wiphy, struct net_device *dev,
 				  bool enabled, int timeout);
@@ -1445,6 +1451,8 @@ struct cfg80211_cached_keys;
  *	set by driver (if supported) on add_interface BEFORE registering the
  *	netdev and may otherwise be used by driver read-only, will be update
  *	by cfg80211 on change_interface
+ * @action_registrations: list of registrations for action frames
+ * @action_registrations_lock: lock for the list
  */
 struct wireless_dev {
 	struct wiphy *wiphy;
@@ -1454,6 +1462,9 @@ struct wireless_dev {
 	struct list_head list;
 	struct net_device *netdev;
 
+	struct list_head action_registrations;
+	spinlock_t action_registrations_lock;
+
 	struct mutex mtx;
 
 	struct work_struct cleanup_work;
@@ -2291,4 +2302,38 @@ void cfg80211_remain_on_channel_expired(struct net_device *dev,
 void cfg80211_new_sta(struct net_device *dev, const u8 *mac_addr,
 		      struct station_info *sinfo, gfp_t gfp);
 
+/**
+ * cfg80211_rx_action - notification of received, unprocessed Action frame
+ * @dev: network device
+ * @freq: Frequency on which the frame was received in MHz
+ * @buf: Action frame (header + body)
+ * @len: length of the frame data
+ * @gfp: context flags
+ * Returns %true if a user space application is responsible for rejecting the
+ *	unrecognized Action frame; %false if no such application is registered
+ *	(i.e., the driver is responsible for rejecting the unrecognized Action
+ *	frame)
+ *
+ * This function is called whenever an Action frame is received for a station
+ * mode interface, but is not processed in kernel.
+ */
+bool cfg80211_rx_action(struct net_device *dev, int freq, const u8 *buf,
+			size_t len, gfp_t gfp);
+
+/**
+ * cfg80211_action_tx_status - notification of TX status for Action frame
+ * @dev: network device
+ * @cookie: Cookie returned by cfg80211_ops::action()
+ * @buf: Action frame (header + body)
+ * @len: length of the frame data
+ * @ack: Whether frame was acknowledged
+ * @gfp: context flags
+ *
+ * This function is called whenever an Action frame was requested to be
+ * transmitted with cfg80211_ops::action() to report the TX status of the
+ * transmission attempt.
+ */
+void cfg80211_action_tx_status(struct net_device *dev, u64 cookie,
+			       const u8 *buf, size_t len, bool ack, gfp_t gfp);
+
 #endif /* __NET_CFG80211_H */

include/net/mac80211.h

@@ -3,7 +3,7 @@
  *
  * Copyright 2002-2005, Devicescape Software, Inc.
  * Copyright 2006-2007	Jiri Benc <jbenc@suse.cz>
- * Copyright 2007-2008	Johannes Berg <johannes@sipsolutions.net>
+ * Copyright 2007-2010	Johannes Berg <johannes@sipsolutions.net>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
@@ -264,6 +264,9 @@ struct ieee80211_bss_conf {
  *	be modified again (no seqno assignment, crypto, etc.)
  * @IEEE80211_TX_INTFL_HAS_RADIOTAP: This frame was injected and still
  *	has a radiotap header at skb->data.
+ * @IEEE80211_TX_INTFL_NL80211_FRAME_TX: Frame was requested through nl80211
+ *	MLME command (internal to mac80211 to figure out whether to send TX
+ *	status to user space)
  */
 enum mac80211_tx_control_flags {
 	IEEE80211_TX_CTL_REQ_TX_STATUS		= BIT(0),
@@ -286,6 +289,7 @@ enum mac80211_tx_control_flags {
 	IEEE80211_TX_CTL_MORE_FRAMES		= BIT(18),
 	IEEE80211_TX_INTFL_RETRANSMISSION	= BIT(19),
 	IEEE80211_TX_INTFL_HAS_RADIOTAP		= BIT(20),
+	IEEE80211_TX_INTFL_NL80211_FRAME_TX	= BIT(21),
 };
 
 /**

net/mac80211/cfg.c

@@ -1,7 +1,7 @@
 /*
  * mac80211 configuration hooks for cfg80211
  *
- * Copyright 2006, 2007	Johannes Berg <johannes@sipsolutions.net>
+ * Copyright 2006-2010	Johannes Berg <johannes@sipsolutions.net>
  *
  * This file is GPLv2 as found in COPYING.
  */
@@ -1448,6 +1448,15 @@ static int ieee80211_cancel_remain_on_channel(struct wiphy *wiphy,
 	return ieee80211_wk_cancel_remain_on_channel(sdata, cookie);
 }
 
+static int ieee80211_action(struct wiphy *wiphy, struct net_device *dev,
+			    struct ieee80211_channel *chan,
+			    enum nl80211_channel_type channel_type,
+			    const u8 *buf, size_t len, u64 *cookie)
+{
+	return ieee80211_mgd_action(IEEE80211_DEV_TO_SUB_IF(dev), chan,
+				    channel_type, buf, len, cookie);
+}
+
 struct cfg80211_ops mac80211_config_ops = {
 	.add_virtual_intf = ieee80211_add_iface,
 	.del_virtual_intf = ieee80211_del_iface,
@@ -1496,4 +1505,5 @@ struct cfg80211_ops mac80211_config_ops = {
 	.set_bitrate_mask = ieee80211_set_bitrate_mask,
 	.remain_on_channel = ieee80211_remain_on_channel,
 	.cancel_remain_on_channel = ieee80211_cancel_remain_on_channel,
+	.action = ieee80211_action,
 };

net/mac80211/ieee80211_i.h

@@ -2,7 +2,7 @@
  * Copyright 2002-2005, Instant802 Networks, Inc.
  * Copyright 2005, Devicescape Software, Inc.
  * Copyright 2006-2007	Jiri Benc <jbenc@suse.cz>
- * Copyright 2007-2008	Johannes Berg <johannes@sipsolutions.net>
+ * Copyright 2007-2010	Johannes Berg <johannes@sipsolutions.net>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
@@ -966,6 +966,10 @@ int ieee80211_mgd_deauth(struct ieee80211_sub_if_data *sdata,
 int ieee80211_mgd_disassoc(struct ieee80211_sub_if_data *sdata,
 			   struct cfg80211_disassoc_request *req,
 			   void *cookie);
+int ieee80211_mgd_action(struct ieee80211_sub_if_data *sdata,
+			 struct ieee80211_channel *chan,
+			 enum nl80211_channel_type channel_type,
+			 const u8 *buf, size_t len, u64 *cookie);
 ieee80211_rx_result ieee80211_sta_rx_mgmt(struct ieee80211_sub_if_data *sdata,
 					  struct sk_buff *skb);
 void ieee80211_send_pspoll(struct ieee80211_local *local,

net/mac80211/mlme.c

@@ -2084,3 +2084,38 @@ int ieee80211_mgd_disassoc(struct ieee80211_sub_if_data *sdata,
 
 	return 0;
 }
+
+int ieee80211_mgd_action(struct ieee80211_sub_if_data *sdata,
+			 struct ieee80211_channel *chan,
+			 enum nl80211_channel_type channel_type,
+			 const u8 *buf, size_t len, u64 *cookie)
+{
+	struct ieee80211_local *local = sdata->local;
+	struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
+	struct sk_buff *skb;
+
+	/* Check that we are on the requested channel for transmission */
+	if ((chan != local->tmp_channel ||
+	     channel_type != local->tmp_channel_type) &&
+	    (chan != local->oper_channel ||
+	     channel_type != local->oper_channel_type))
+		return -EBUSY;
+
+	skb = dev_alloc_skb(local->hw.extra_tx_headroom + len);
+	if (!skb)
+		return -ENOMEM;
+	skb_reserve(skb, local->hw.extra_tx_headroom);
+
+	memcpy(skb_put(skb, len), buf, len);
+
+	if (!(ifmgd->flags & IEEE80211_STA_MFP_ENABLED))
+		IEEE80211_SKB_CB(skb)->flags |=
+			IEEE80211_TX_INTFL_DONT_ENCRYPT;
+	IEEE80211_SKB_CB(skb)->flags |= IEEE80211_TX_INTFL_NL80211_FRAME_TX |
+		IEEE80211_TX_CTL_REQ_TX_STATUS;
+	skb->dev = sdata->dev;
+	ieee80211_tx_skb(sdata, skb);
+
+	*cookie = (unsigned long) skb;
+	return 0;
+}

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;
 }

net/mac80211/status.c

@@ -2,7 +2,7 @@
  * Copyright 2002-2005, Instant802 Networks, Inc.
  * Copyright 2005-2006, Devicescape Software, Inc.
  * Copyright 2006-2007	Jiri Benc <jbenc@suse.cz>
- * Copyright 2008-2009	Johannes Berg <johannes@sipsolutions.net>
+ * Copyright 2008-2010	Johannes Berg <johannes@sipsolutions.net>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
@@ -288,6 +288,11 @@ void ieee80211_tx_status(struct ieee80211_hw *hw, struct sk_buff *skb)
 					msecs_to_jiffies(10));
 	}
 
+	if (info->flags & IEEE80211_TX_INTFL_NL80211_FRAME_TX)
+		cfg80211_action_tx_status(
+			skb->dev, (unsigned long) skb, skb->data, skb->len,
+			!!(info->flags & IEEE80211_TX_STAT_ACK), GFP_ATOMIC);
+
 	/* this was a transmitted frame, but now we want to reuse it */
 	skb_orphan(skb);