[PATCH] cfg80211: support 4-way handshake offloading for WPA/WPA2-PSK

[Johannes Berg <johannes@sipsolutions.net>]

From: Eliad Peller <eliad@wizery.com>

Let drivers advertise support for station-mode 4-way handshake
offloading with a new NL80211_EXT_FEATURE_4WAY_HANDSHAKE_OFFLOAD_STA
flag.

Add a new NL80211_ATTR_PMK attribute that might be passed as part
of NL80211_CMD_CONNECT command, and contain the PSK (which is the
PMK, hence the name.)

The driver/device is assumed to handle the 4-way handshake by
itself in this case (including key derivations, etc.), instead
of relying on the supplicant.

This patch is somewhat based on this one (by Vladimir Kondratiev):
https://patchwork.kernel.org/patch/1309561/.

Signed-off-by: Vladimir Kondratiev <qca_vkondrat@qca.qualcomm.com>
Signed-off-by: Eliad Peller <eliadx.peller@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
---
 include/linux/ieee80211.h    | 1 +
 include/net/cfg80211.h       | 2 ++
 include/uapi/linux/nl80211.h | 9 +++++++++
 net/wireless/nl80211.c       | 8 ++++++++
 4 files changed, 20 insertions(+)

diff --git a/include/linux/ieee80211.h b/include/linux/ieee80211.h
index 6ea381c98aae..2049e983a994 100644
--- a/include/linux/ieee80211.h
+++ b/include/linux/ieee80211.h
@@ -2357,6 +2357,7 @@ enum ieee80211_sa_query_action {
 #define WLAN_MAX_KEY_LEN		32
 
 #define WLAN_PMKID_LEN			16
+#define WLAN_PMK_LEN			32
 
 #define WLAN_OUI_WFA			0x506f9a
 #define WLAN_OUI_TYPE_WFA_P2P		9
diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index 86c12f85fb53..4ca968927d60 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -643,6 +643,7 @@ struct survey_info {
  * @wep_keys: static WEP keys, if not NULL points to an array of
  *	CFG80211_MAX_WEP_KEYS WEP keys
  * @wep_tx_key: key index (0..3) of the default TX static WEP key
+ * @psk: PSK (for devices supporting 4-way-handshake offload)
  */
 struct cfg80211_crypto_settings {
 	u32 wpa_versions;
@@ -656,6 +657,7 @@ struct cfg80211_crypto_settings {
 	bool control_port_no_encrypt;
 	struct key_params *wep_keys;
 	int wep_tx_key;
+	const u8 *psk;
 };
 
 /**
diff --git a/include/uapi/linux/nl80211.h b/include/uapi/linux/nl80211.h
index 9a499b15cfbc..ba102c937750 100644
--- a/include/uapi/linux/nl80211.h
+++ b/include/uapi/linux/nl80211.h
@@ -2012,6 +2012,9 @@ enum nl80211_commands {
  *	u32 attribute with an &enum nl80211_timeout_reason value. This is used,
  *	e.g., with %NL80211_CMD_CONNECT event.
  *
+ * @NL80211_ATTR_PMK: PSK for offloaded 4-Way Handshake. Relevant only
+ *	with %NL80211_CMD_CONNECT (for WPA/WPA2-PSK networks).
+ *
  * @NUM_NL80211_ATTR: total number of nl80211_attrs available
  * @NL80211_ATTR_MAX: highest attribute number currently defined
  * @__NL80211_ATTR_AFTER_LAST: internal use
@@ -2423,6 +2426,8 @@ enum nl80211_attrs {
 
 	NL80211_ATTR_TIMEOUT_REASON,
 
+	NL80211_ATTR_PMK,
+
 	/* add attributes here, update the policy in nl80211.c */
 
 	__NL80211_ATTR_AFTER_LAST,
@@ -4759,6 +4764,9 @@ enum nl80211_feature_flags {
  * @NL80211_EXT_FEATURE_CQM_RSSI_LIST: With this driver the
  *	%NL80211_ATTR_CQM_RSSI_THOLD attribute accepts a list of zero or more
  *	RSSI threshold values to monitor rather than exactly one threshold.
+ * @NL80211_EXT_FEATURE_4WAY_HANDSHAKE_OFFLOAD_STA: Device supports
+ *	doing 4-way handshake in station mode (PSK is passed as part
+ *	of the connect command).
  *
  * @NUM_NL80211_EXT_FEATURES: number of extended features.
  * @MAX_NL80211_EXT_FEATURES: highest extended feature index.
@@ -4778,6 +4786,7 @@ enum nl80211_ext_feature_index {
 	NL80211_EXT_FEATURE_MGMT_TX_RANDOM_TA_CONNECTED,
 	NL80211_EXT_FEATURE_SCHED_SCAN_RELATIVE_RSSI,
 	NL80211_EXT_FEATURE_CQM_RSSI_LIST,
+	NL80211_EXT_FEATURE_4WAY_HANDSHAKE_OFFLOAD_STA,
 
 	/* add new features before the definition below */
 	NUM_NL80211_EXT_FEATURES,
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index d516527fcb8e..34b551edbc4f 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -410,6 +410,7 @@ static const struct nla_policy nl80211_policy[NUM_NL80211_ATTR] = {
 		.len = sizeof(struct nl80211_bss_select_rssi_adjust)
 	},
 	[NL80211_ATTR_TIMEOUT_REASON] = { .type = NLA_U32 },
+	[NL80211_ATTR_PMK] = { .len = WLAN_PMK_LEN },
 };
 
 /* policy for the key attributes */
@@ -8039,6 +8040,13 @@ static int nl80211_crypto_settings(struct cfg80211_registered_device *rdev,
 		memcpy(settings->akm_suites, data, len);
 	}
 
+	if (info->attrs[NL80211_ATTR_PMK]) {
+		if (!wiphy_ext_feature_isset(&rdev->wiphy,
+					     NL80211_EXT_FEATURE_4WAY_HANDSHAKE_OFFLOAD_STA))
+			return -EINVAL;
+		settings->psk = nla_data(info->attrs[NL80211_ATTR_PMK]);
+	}
+
 	return 0;
 }
 
-- 
2.9.3