Merge branch 'eapol-over-nl80211' into mac80211-next

This is the EAPoL over nl80211 patchset from Denis Kenzior, minus some
infrastructure patches I'd split out and applied earlier. Denis described
it as follows:

This patchset adds support for running 802.11 authentication mechanisms (e.g.
802.1X, 4-Way Handshake, etc) over NL80211 instead of putting them onto the
network device.  This has the advantage of fixing several long-standing race
conditions that result from userspace operating on multiple transports in order
to manage a 802.11 connection (e.g. NL80211 and wireless netdev, wlan0, etc).

For example, userspace would sometimes see 4-Way handshake packets before
NL80211 signaled that the connection has been established.  Leading to ugly
hacks or having the STA wait for retransmissions from the AP.

This also provides a way to mitigate a particularly nasty race condition where
the encryption key could be set prior to the 4-way handshake packet 4/4 being
sent.  This would result in the packet being sent encrypted and discarded by
the peer.  The mitigation strategy for this race is for userspace to explicitly
tell the kernel that a particular EAPoL packet should not be encrypted.

To make this possible this patchset introduces a new NL80211 command and several
new attributes.  A userspace that is capable of processing EAPoL packets over
NL80211 includes a new NL80211_ATTR_CONTROL_PORT_OVER_NL80211 attribute in its
NL80211_CMD_ASSOCIATE or NL80211_CMD_CONNECT requests being sent to the kernel.
The previously added NL80211_ATTR_SOCKET_OWNER attribute must also be included.
The latter is used by the kernel to send NL80211_CMD_CONTROL_PORT_FRAME
notifications back to userspace via a netlink unicast.  If the
NL80211_ATTR_CONTROL_PORT_OVER_NL80211 attribute is not specified, then legacy
behavior is kept and control port packets continue to flow over the network
interface.

If control port over nl80211 transport is requested, then control port packets
are intercepted just prior to being handed to the network device and sent over
netlink via the NL80211_CMD_CONTROL_PORT_FRAME notification.
NL80211_ATTR_CONTROL_PORT_ETHERTYPE and NL80211_ATTR_MAC are included to
specify the control port frame protocol and source address respectively.  If
the control port frame was received unencrypted then
NL80211_ATTR_CONTROL_PORT_NO_ENCRYPT flag is also included.  NL80211_ATTR_FRAME
attribute contains the raw control port frame with all transport layer headers
stripped (e.g. this would be the raw EAPoL frame).

Userspace can reply to control port frames either via legacy methods (by sending
frames to the network device) or via NL80211_CMD_CONTROL_PORT_FRAME request.
Userspace would included NL80211_ATTR_FRAME with the raw control port frame as
well as NL80211_Attr_MAC and NL80211_ATTR_CONTROL_PORT_ETHERTYPE attributes to
specify the destination address and protocol respectively.  This allows
Pre-Authentication (protocol 0x88c7) frames to be sent via this mechanism as
well.  Finally, NL80211_ATTR_CONTROL_PORT_NO_ENCRYPT flag can be included to
tell the driver to send the frame unencrypted, e.g. for 4-Way handshake 4/4
frames.

The proposed patchset has been tested in a mac80211_hwsim based environment with
hostapd and iwd.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 29 insertions, 1 deletions

diff --git a/include/uapi/linux/nl80211.h b/include/uapi/linux/nl80211.h
index 9ea3d6039eca..15daf5e2638d 100644
--- a/include/uapi/linux/nl80211.h
+++ b/include/uapi/linux/nl80211.h
@@ -542,7 +542,8 @@
  *	IEs in %NL80211_ATTR_IE, %NL80211_ATTR_AUTH_TYPE, %NL80211_ATTR_USE_MFP,
  *	%NL80211_ATTR_MAC, %NL80211_ATTR_WIPHY_FREQ, %NL80211_ATTR_CONTROL_PORT,
  *	%NL80211_ATTR_CONTROL_PORT_ETHERTYPE,
- *	%NL80211_ATTR_CONTROL_PORT_NO_ENCRYPT, %NL80211_ATTR_MAC_HINT, and
+ *	%NL80211_ATTR_CONTROL_PORT_NO_ENCRYPT,
+ *	%NL80211_ATTR_CONTROL_PORT_OVER_NL80211, %NL80211_ATTR_MAC_HINT, and
  *	%NL80211_ATTR_WIPHY_FREQ_HINT.
  *	If included, %NL80211_ATTR_MAC and %NL80211_ATTR_WIPHY_FREQ are
  *	restrictions on BSS selection, i.e., they effectively prevent roaming
@@ -990,6 +991,17 @@
  *	&NL80211_CMD_CONNECT or &NL80211_CMD_ROAM. If the 4 way handshake failed
  *	&NL80211_CMD_DISCONNECT should be indicated instead.
  *
+ * @NL80211_CMD_CONTROL_PORT_FRAME: Control Port (e.g. PAE) frame TX request
+ *	and RX notification.  This command is used both as a request to transmit
+ *	a control port frame and as a notification that a control port frame
+ *	has been received. %NL80211_ATTR_FRAME is used to specify the
+ *	frame contents.  The frame is the raw EAPoL data, without ethernet or
+ *	802.11 headers.
+ *	When used as an event indication %NL80211_ATTR_CONTROL_PORT_ETHERTYPE,
+ *	%NL80211_ATTR_CONTROL_PORT_NO_ENCRYPT and %NL80211_ATTR_MAC are added
+ *	indicating the protocol type of the received frame; whether the frame
+ *	was received unencrypted and the MAC address of the peer respectively.
+ *
  * @NL80211_CMD_RELOAD_REGDB: Request that the regdb firmware file is reloaded.
  *
  * @NL80211_CMD_EXTERNAL_AUTH: This interface is exclusively defined for host
@@ -1228,6 +1240,8 @@ enum nl80211_commands {
 
 	NL80211_CMD_STA_OPMODE_CHANGED,
 
+	NL80211_CMD_CONTROL_PORT_FRAME,
+
 	/* add new commands above here */
 
 	/* used to define NL80211_CMD_MAX below */
@@ -1475,6 +1489,15 @@ enum nl80211_commands {
  * @NL80211_ATTR_CONTROL_PORT_NO_ENCRYPT: When included along with
  *	%NL80211_ATTR_CONTROL_PORT_ETHERTYPE, indicates that the custom
  *	ethertype frames used for key negotiation must not be encrypted.
+ * @NL80211_ATTR_CONTROL_PORT_OVER_NL80211: A flag indicating whether control
+ *	port frames (e.g. of type given in %NL80211_ATTR_CONTROL_PORT_ETHERTYPE)
+ *	will be sent directly to the network interface or sent via the NL80211
+ *	socket.  If this attribute is missing, then legacy behavior of sending
+ *	control port frames directly to the network interface is used.  If the
+ *	flag is included, then control port frames are sent over NL80211 instead
+ *	using %CMD_CONTROL_PORT_FRAME.  If control port routing over NL80211 is
+ *	to be used then userspace must also use the %NL80211_ATTR_SOCKET_OWNER
+ *	flag.
  *
  * @NL80211_ATTR_TESTDATA: Testmode data blob, passed through to the driver.
  *	We recommend using nested, driver-specific attributes within this.
@@ -2634,6 +2657,8 @@ enum nl80211_attrs {
 	NL80211_ATTR_NSS,
 	NL80211_ATTR_ACK_SIGNAL,
 
+	NL80211_ATTR_CONTROL_PORT_OVER_NL80211,
+
 	/* add attributes here, update the policy in nl80211.c */
 
 	__NL80211_ATTR_AFTER_LAST,
@@ -5011,6 +5036,8 @@ enum nl80211_feature_flags {
  *	channel change triggered by radar detection event.
  *	No need to start CAC from user-space, no need to react to
  *	"radar detected" event.
+ * @NL80211_EXT_FEATURE_CONTROL_PORT_OVER_NL80211: Driver supports sending and
+ *	receiving control port frames over nl80211 instead of the netdevice.
  *
  * @NUM_NL80211_EXT_FEATURES: number of extended features.
  * @MAX_NL80211_EXT_FEATURES: highest extended feature index.
@@ -5042,6 +5069,7 @@ enum nl80211_ext_feature_index {
 	NL80211_EXT_FEATURE_LOW_POWER_SCAN,
 	NL80211_EXT_FEATURE_HIGH_ACCURACY_SCAN,
 	NL80211_EXT_FEATURE_DFS_OFFLOAD,
+	NL80211_EXT_FEATURE_CONTROL_PORT_OVER_NL80211,
 
 	/* add new features before the definition below */
 	NUM_NL80211_EXT_FEATURES,