cfg80211/mac80211: extensible frame processing

Allow userspace to register for more than just
action frames by giving the frame subtype, and
make it possible to use this in various modes
as well.

With some tweaks and some added functionality
this will, in the future, also be usable in AP
mode and be able to replace the cooked monitor
interface currently used in that case.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

2 files changed, 108 insertions, 41 deletions

diff --git a/include/linux/nl80211.h b/include/linux/nl80211.h
index 2c87016..8af1e66 100644
--- a/include/linux/nl80211.h
+++ b/include/linux/nl80211.h
@@ -40,6 +40,43 @@
  */
 
 /**
+ * DOC: Frame transmission/registration support
+ *
+ * Frame transmission and registration support exists to allow userspace
+ * management entities such as wpa_supplicant react to management frames
+ * that are not being handled by the kernel. This includes, for example,
+ * certain classes of action frames that cannot be handled in the kernel
+ * for various reasons.
+ *
+ * Frame registration is done on a per-interface basis and registrations
+ * cannot be removed other than by closing the socket. It is possible to
+ * specify a registration filter to register, for example, only for a
+ * certain type of action frame. In particular with action frames, those
+ * that userspace registers for will not be returned as unhandled by the
+ * driver, so that the registered application has to take responsibility
+ * for doing that.
+ *
+ * The type of frame that can be registered for is also dependent on the
+ * driver and interface type. The frame types are advertised in wiphy
+ * attributes so applications know what to expect.
+ *
+ * NOTE: When an interface changes type while registrations are active,
+ *       these registrations are ignored until the interface type is
+ *       changed again. This means that changing the interface type can
+ *       lead to a situation that couldn't otherwise be produced, but
+ *       any such registrations will be dormant in the sense that they
+ *       will not be serviced, i.e. they will not receive any frames.
+ *
+ * Frame transmission allows userspace to send for example the required
+ * responses to action frames. It is subject to some sanity checking,
+ * but many frames can be transmitted. When a frame was transmitted, its
+ * status is indicated to the sending socket.
+ *
+ * For more technical details, see the corresponding command descriptions
+ * below.
+ */
+
+/**
  * enum nl80211_commands - supported nl80211 commands
  *
  * @NL80211_CMD_UNSPEC: unspecified command to catch errors
@@ -301,16 +338,18 @@
  *	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
+ * @NL80211_CMD_REGISTER_FRAME: Register for receiving certain mgmt frames
+ *	(via @NL80211_CMD_FRAME) for processing in userspace. This command
+ *	requires an interface index, a frame type attribute (optional for
+ *	backward compatibility reasons, if not given assumes action frames)
+ *	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_FRAME: Management frame TX request and RX notification. This
+ *	command is used both as a request to transmit a management frame and
+ *	as an event indicating reception of a 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
@@ -320,8 +359,8 @@
  *	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
+ * @NL80211_CMD_FRAME_TX_STATUS: Report TX status of a management frame
+ *	transmitted with %NL80211_CMD_FRAME. %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.
@@ -429,9 +468,12 @@ enum nl80211_commands {
 
 	NL80211_CMD_SET_TX_BITRATE_MASK,
 
-	NL80211_CMD_REGISTER_ACTION,
-	NL80211_CMD_ACTION,
-	NL80211_CMD_ACTION_TX_STATUS,
+	NL80211_CMD_REGISTER_FRAME,
+	NL80211_CMD_REGISTER_ACTION = NL80211_CMD_REGISTER_FRAME,
+	NL80211_CMD_FRAME,
+	NL80211_CMD_ACTION = NL80211_CMD_FRAME,
+	NL80211_CMD_FRAME_TX_STATUS,
+	NL80211_CMD_ACTION_TX_STATUS = NL80211_CMD_FRAME_TX_STATUS,
 
 	NL80211_CMD_SET_POWER_SAVE,
 	NL80211_CMD_GET_POWER_SAVE,
@@ -708,7 +750,16 @@ enum nl80211_commands {
  *	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.
+ *	at least one byte, currently used with @NL80211_CMD_REGISTER_FRAME.
+ * @NL80211_ATTR_FRAME_TYPE: A u16 indicating the frame type/subtype for the
+ *	@NL80211_CMD_REGISTER_FRAME command.
+ * @NL80211_ATTR_TX_FRAME_TYPES: wiphy capability attribute, which is a
+ *	nested attribute of %NL80211_ATTR_FRAME_TYPE attributes, containing
+ *	information about which frame types can be transmitted with
+ *	%NL80211_CMD_FRAME.
+ * @NL80211_ATTR_RX_FRAME_TYPES: wiphy capability attribute, which is a
+ *	nested attribute of %NL80211_ATTR_FRAME_TYPE attributes, containing
+ *	information about which frame types can be registered for RX.
  *
  * @NL80211_ATTR_ACK: Flag attribute indicating that the frame was
  *	acknowledged by the recipient.
@@ -891,6 +942,10 @@ enum nl80211_attrs {
 	NL80211_ATTR_WIPHY_TX_POWER_SETTING,
 	NL80211_ATTR_WIPHY_TX_POWER_LEVEL,
 
+	NL80211_ATTR_TX_FRAME_TYPES,
+	NL80211_ATTR_RX_FRAME_TYPES,
+	NL80211_ATTR_FRAME_TYPE,
+
 	/* add attributes here, update the policy in nl80211.c */
 
 	__NL80211_ATTR_AFTER_LAST,
@@ -947,7 +1002,7 @@ enum nl80211_attrs {
  * @NL80211_IFTYPE_MONITOR: monitor interface receiving all frames
  * @NL80211_IFTYPE_MESH_POINT: mesh point
  * @NL80211_IFTYPE_MAX: highest interface type number currently defined
- * @__NL80211_IFTYPE_AFTER_LAST: internal use
+ * @NUM_NL80211_IFTYPES: number of defined interface types
  *
  * These values are used with the %NL80211_ATTR_IFTYPE
  * to set the type of an interface.
@@ -964,8 +1019,8 @@ enum nl80211_iftype {
 	NL80211_IFTYPE_MESH_POINT,
 
 	/* keep last */
-	__NL80211_IFTYPE_AFTER_LAST,
-	NL80211_IFTYPE_MAX = __NL80211_IFTYPE_AFTER_LAST - 1
+	NUM_NL80211_IFTYPES,
+	NL80211_IFTYPE_MAX = NUM_NL80211_IFTYPES - 1
 };
 
 /**
diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index 2b403c7..6a98b1b 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -1020,7 +1020,7 @@ 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
+ * @mgmt_tx: Transmit a management frame
  *
  * @testmode_cmd: run a test mode command
  *
@@ -1172,7 +1172,7 @@ struct cfg80211_ops {
 					    struct net_device *dev,
 					    u64 cookie);
 
-	int	(*action)(struct wiphy *wiphy, struct net_device *dev,
+	int	(*mgmt_tx)(struct wiphy *wiphy, struct net_device *dev,
 			  struct ieee80211_channel *chan,
 			  enum nl80211_channel_type channel_type,
 			  bool channel_type_valid,
@@ -1236,6 +1236,10 @@ struct mac_address {
 	u8 addr[ETH_ALEN];
 };
 
+struct ieee80211_txrx_stypes {
+	u16 tx, rx;
+};
+
 /**
  * struct wiphy - wireless hardware description
  * @reg_notifier: the driver's regulatory notification callback
@@ -1286,6 +1290,10 @@ struct mac_address {
  * @privid: a pointer that drivers can use to identify if an arbitrary
  *	wiphy is theirs, e.g. in global notifiers
  * @bands: information about bands/channels supported by this device
+ *
+ * @mgmt_stypes: bitmasks of frame subtypes that can be subscribed to or
+ *	transmitted through nl80211, points to an array indexed by interface
+ *	type
  */
 struct wiphy {
 	/* assign these fields before you register the wiphy */
@@ -1294,9 +1302,12 @@ struct wiphy {
 	u8 perm_addr[ETH_ALEN];
 	u8 addr_mask[ETH_ALEN];
 
-	u16 n_addresses;
 	struct mac_address *addresses;
 
+	const struct ieee80211_txrx_stypes *mgmt_stypes;
+
+	u16 n_addresses;
+
 	/* Supported interface modes, OR together BIT(NL80211_IFTYPE_...) */
 	u16 interface_modes;
 
@@ -1492,8 +1503,8 @@ 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
+ * @mgmt_registrations: list of registrations for management frames
+ * @mgmt_registrations_lock: lock for the list
  * @mtx: mutex used to lock data in this struct
  * @cleanup_work: work struct used for cleanup that can't be done directly
  */
@@ -1505,8 +1516,8 @@ struct wireless_dev {
 	struct list_head list;
 	struct net_device *netdev;
 
-	struct list_head action_registrations;
-	spinlock_t action_registrations_lock;
+	struct list_head mgmt_registrations;
+	spinlock_t mgmt_registrations_lock;
 
 	struct mutex mtx;
 
@@ -2373,38 +2384,39 @@ 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
+ * cfg80211_rx_mgmt - notification of received, unprocessed management frame
  * @dev: network device
  * @freq: Frequency on which the frame was received in MHz
- * @buf: Action frame (header + body)
+ * @buf: Management 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)
+ *
+ * Returns %true if a user space application has registered for this frame.
+ * For action frames, that makes it responsible for rejecting unrecognized
+ * action frames; %false otherwise, in which case for action frames the
+ * driver is responsible for rejecting the 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);
+bool cfg80211_rx_mgmt(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
+ * cfg80211_mgmt_tx_status - notification of TX status for management frame
  * @dev: network device
- * @cookie: Cookie returned by cfg80211_ops::action()
- * @buf: Action frame (header + body)
+ * @cookie: Cookie returned by cfg80211_ops::mgmt_tx()
+ * @buf: Management 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
+ * This function is called whenever a management frame was requested to be
+ * transmitted with cfg80211_ops::mgmt_tx() 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);
+void cfg80211_mgmt_tx_status(struct net_device *dev, u64 cookie,
+			     const u8 *buf, size_t len, bool ack, gfp_t gfp);
 
 
 /**