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>

1 files changed, 74 insertions, 19 deletions

diff --git a/include/linux/nl80211.h b/include/linux/nl80211.h
index 2c8701687336..8af1e66c3cf9 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
 };
 
 /**