[PATCH v1] 4-way handshake offloading

[PATCH v1] 4-way handshake offloading

[Vladimir Kondratiev]

Adding 4-way handshake offload support.

Intention is to support "smart" devices in P2P flow - they tend to
offload as much as possible.

This patch address WPA2-Personal - this is what P2P uses.
WPA2-Enterprise not supported yet.

Currently, ath6kl driver can use this feature (patch in works),
and wil6210 (60g) driver can work only in the offload mode - 
working on security flow right now.

Corresponding patch for WPA supplicant almost ready (by Jouni).
for WPA supplicant, STA part verified; AP not finalized yet.

Vladimir Kondratiev (1):
  cfg80211: Support for 4-way handshake offloading for WPA2-Personal

 include/linux/ieee80211.h |    2 ++
 include/linux/nl80211.h   |   19 +++++++++++++++++++
 include/net/cfg80211.h    |    7 +++++++
 net/wireless/nl80211.c    |   16 ++++++++++++++++
 4 files changed, 44 insertions(+)

-- 
1.7.9.5

[PATCH v1] cfg80211: Support for 4-way handshake offloading for WPA2-Personal

[Vladimir Kondratiev]

Traditionally, WPA supplicant handle 4-way handshake and do all key derivation.
First, PSK calculated from the passphrase and SSID.
Finally, PTK supplied to the driver with add_key()

For firmware to implement offload, it need PSK.
In case of WPA2-Personal, PSK is available on the connect()/start_ap() time.

In case of WPS2-Enterprise, the PSK will be available only after the EAP authentication,
this is not addressed with this patch.

Based on code from
Rishi Panjwani <rpanjwan@qca.qualcomm.com>

Signed-off-by: Vladimir Kondratiev <qca_vkondrat@qca.qualcomm.com>
---
 include/linux/ieee80211.h |    2 ++
 include/linux/nl80211.h   |   19 +++++++++++++++++++
 include/net/cfg80211.h    |    7 +++++++
 net/wireless/nl80211.c    |   16 ++++++++++++++++
 4 files changed, 44 insertions(+)

diff --git a/include/linux/ieee80211.h b/include/linux/ieee80211.h
index e02fc68..95aafb3 100644
--- a/include/linux/ieee80211.h
+++ b/include/linux/ieee80211.h
@@ -1787,6 +1787,8 @@ enum ieee80211_sa_query_action {
 
 #define WLAN_PMKID_LEN			16
 
+#define WLAN_PSK_LEN			32
+
 #define WLAN_OUI_WFA			0x506f9a
 #define WLAN_OUI_TYPE_WFA_P2P		9
 #define WLAN_OUI_MICROSOFT		0x0050f2
diff --git a/include/linux/nl80211.h b/include/linux/nl80211.h
index 2f38788..64f01a3 100644
--- a/include/linux/nl80211.h
+++ b/include/linux/nl80211.h
@@ -1251,6 +1251,21 @@ enum nl80211_commands {
  *	was used to provide the hint. For the different types of
  *	allowed user regulatory hints see nl80211_user_reg_hint_type.
  *
+ * @NL80211_ATTR_4WAY_HANDSHAKE_OFFLOAD_STA: This is a flag that indicates to
+ *	WPA supplicant that 4-way handshake has been offloaded to the firmware
+ *	in the STA mode.
+ *	In this case, WPA supplicant will provide driver with PSK for
+ *	connect()
+ *
+ * @NL80211_ATTR_4WAY_HANDSHAKE_OFFLOAD_AP: This is a flag that indicates to
+ *	WPA supplicant that 4-way handshake has been offloaded to the firmware
+ *	in the AP mode.
+ *	In this case, WPA supplicant will provide driver with PSK for
+ *	start_ap()
+ *
+ * @NL80211_ATTR_PSK: The PSK calculated by WPA supplicant
+ *	length is WLAN_PSK_LEN (32) bytes
+ *
  * @NL80211_ATTR_MAX: highest attribute number currently defined
  * @__NL80211_ATTR_AFTER_LAST: internal use
  */
@@ -1506,6 +1521,10 @@ enum nl80211_attrs {
 
 	NL80211_ATTR_USER_REG_HINT_TYPE,
 
+	NL80211_ATTR_4WAY_HANDSHAKE_OFFLOAD_STA,
+	NL80211_ATTR_4WAY_HANDSHAKE_OFFLOAD_AP,
+	NL80211_ATTR_PSK,
+
 	/* add attributes here, update the policy in nl80211.c */
 
 	__NL80211_ATTR_AFTER_LAST,
diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index 493fa0c..4e3adb1 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -436,6 +436,7 @@ struct cfg80211_beacon_data {
  * @privacy: the BSS uses privacy
  * @auth_type: Authentication type (algorithm)
  * @inactivity_timeout: time in seconds to determine station's inactivity.
+ * @psk: The PSK that has been calculated by WPA supplicant
  */
 struct cfg80211_ap_settings {
 	struct ieee80211_channel *channel;
@@ -451,6 +452,7 @@ struct cfg80211_ap_settings {
 	bool privacy;
 	enum nl80211_auth_type auth_type;
 	int inactivity_timeout;
+	const u8 *psk;
 };
 
 /**
@@ -1305,6 +1307,7 @@ struct cfg80211_ibss_params {
  * @ht_capa:  HT Capabilities over-rides.  Values set in ht_capa_mask
  *   will be used in ht_capa.  Un-supported values will be ignored.
  * @ht_capa_mask:  The bits of ht_capa which are to be used.
+ * @psk: The PSK that has been calculated by WPA supplicant
  */
 struct cfg80211_connect_params {
 	struct ieee80211_channel *channel;
@@ -1322,6 +1325,7 @@ struct cfg80211_connect_params {
 	int bg_scan_period;
 	struct ieee80211_ht_cap ht_capa;
 	struct ieee80211_ht_cap ht_capa_mask;
+	const u8 *psk;
 };
 
 /**
@@ -1896,6 +1900,7 @@ struct cfg80211_ops {
  *	responds to probe-requests in hardware.
  * @WIPHY_FLAG_OFFCHAN_TX: Device supports direct off-channel TX.
  * @WIPHY_FLAG_HAS_REMAIN_ON_CHANNEL: Device supports remain-on-channel call.
+ * @WIPHY_FLAG_4WAY_HANDSHAKE_OFFLOAD: Device supports 4-way handshake offload.
  */
 enum wiphy_flags {
 	WIPHY_FLAG_CUSTOM_REGULATORY		= BIT(0),
@@ -1919,6 +1924,8 @@ enum wiphy_flags {
 	WIPHY_FLAG_AP_PROBE_RESP_OFFLOAD	= BIT(19),
 	WIPHY_FLAG_OFFCHAN_TX			= BIT(20),
 	WIPHY_FLAG_HAS_REMAIN_ON_CHANNEL	= BIT(21),
+	WIPHY_FLAG_4WAY_HANDSHAKE_OFFLOAD_STA	= BIT(22),
+	WIPHY_FLAG_4WAY_HANDSHAKE_OFFLOAD_AP	= BIT(23),
 };
 
 /**
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 50b1a0e..3cdff4d 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -355,6 +355,10 @@ static const struct nla_policy nl80211_policy[NL80211_ATTR_MAX+1] = {
 	[NL80211_ATTR_BG_SCAN_PERIOD] = { .type = NLA_U16 },
 	[NL80211_ATTR_WDEV] = { .type = NLA_U64 },
 	[NL80211_ATTR_USER_REG_HINT_TYPE] = { .type = NLA_U32 },
+	[NL80211_ATTR_4WAY_HANDSHAKE_OFFLOAD_STA] = { .type = NLA_FLAG },
+	[NL80211_ATTR_4WAY_HANDSHAKE_OFFLOAD_AP] = { .type = NLA_FLAG },
+	[NL80211_ATTR_PSK] = { .type = NLA_BINARY,
+			       .len = WLAN_PSK_LEN },
 };
 
 /* policy for the key attributes */
@@ -914,6 +918,12 @@ static int nl80211_send_wiphy(struct sk_buff *msg, u32 pid, u32 seq, int flags,
 	if ((dev->wiphy.flags & WIPHY_FLAG_TDLS_EXTERNAL_SETUP) &&
 	    nla_put_flag(msg, NL80211_ATTR_TDLS_EXTERNAL_SETUP))
 		goto nla_put_failure;
+	if ((dev->wiphy.flags & WIPHY_FLAG_4WAY_HANDSHAKE_OFFLOAD_STA) &&
+	    nla_put_flag(msg, NL80211_ATTR_4WAY_HANDSHAKE_OFFLOAD_STA))
+		goto nla_put_failure;
+	if ((dev->wiphy.flags & WIPHY_FLAG_4WAY_HANDSHAKE_OFFLOAD_AP) &&
+	    nla_put_flag(msg, NL80211_ATTR_4WAY_HANDSHAKE_OFFLOAD_AP))
+		goto nla_put_failure;
 
 	if (nla_put(msg, NL80211_ATTR_CIPHER_SUITES,
 		    sizeof(u32) * dev->wiphy.n_cipher_suites,
@@ -2576,6 +2586,9 @@ static int nl80211_start_ap(struct sk_buff *skb, struct genl_info *info)
 					  params.channel_type))
 		return -EINVAL;
 
+	if (info->attrs[NL80211_ATTR_PSK])
+		params.psk = nla_data(info->attrs[NL80211_ATTR_PSK]);
+
 	mutex_lock(&rdev->devlist_mtx);
 	err = cfg80211_can_use_chan(rdev, wdev, params.channel,
 				    CHAN_MODE_SHARED);
@@ -5640,6 +5653,9 @@ static int nl80211_connect(struct sk_buff *skb, struct genl_info *info)
 		       sizeof(connect.ht_capa));
 	}
 
+	if (info->attrs[NL80211_ATTR_PSK])
+		connect.psk = nla_data(info->attrs[NL80211_ATTR_PSK]);
+
 	err = cfg80211_connect(rdev, dev, &connect, connkeys);
 	if (err)
 		kfree(connkeys);
-- 
1.7.9.5

Re: [PATCH v1] cfg80211: Support for 4-way handshake offloading for WPA2-Personal

[Johannes Berg]

On Thu, 2012-08-02 at 14:33 +0300, Vladimir Kondratiev wrote:

> + * @NL80211_ATTR_4WAY_HANDSHAKE_OFFLOAD_STA: This is a flag that indicates to
> + *	WPA supplicant that 4-way handshake has been offloaded to the firmware
> + *	in the STA mode.
> + *	In this case, WPA supplicant will provide driver with PSK for
> + *	connect()
> + *
> + * @NL80211_ATTR_4WAY_HANDSHAKE_OFFLOAD_AP: This is a flag that indicates to
> + *	WPA supplicant that 4-way handshake has been offloaded to the firmware
> + *	in the AP mode.
> + *	In this case, WPA supplicant will provide driver with PSK for
> + *	start_ap()

I think you should use the nl80211 driver flags, not extra attributes
here.

>  struct cfg80211_connect_params {
>  	struct ieee80211_channel *channel;
> @@ -1322,6 +1325,7 @@ struct cfg80211_connect_params {
>  	int bg_scan_period;
>  	struct ieee80211_ht_cap ht_capa;
>  	struct ieee80211_ht_cap ht_capa_mask;
> +	const u8 *psk;
>  };

And the descriptions (and flag checking!) should make it clear that it
is only supported with the connect() API, not with the auth/assoc APIs.

 
> + * @WIPHY_FLAG_4WAY_HANDSHAKE_OFFLOAD: Device supports 4-way handshake offload.

Use nl80211 flag directly. Also, docs are wrong:

> +	WIPHY_FLAG_4WAY_HANDSHAKE_OFFLOAD_STA	= BIT(22),
> +	WIPHY_FLAG_4WAY_HANDSHAKE_OFFLOAD_AP	= BIT(23),


Please also add validation that these flags are specified only when the
correct APIs (connect/start_ap) are supported.

johannes

Re: [PATCH v1] cfg80211: Support for 4-way handshake offloading for WPA2-Personal

[Vladimir Kondratiev]

On Monday, August 20, 2012 01:20:29 PM Johannes Berg wrote:
> On Thu, 2012-08-02 at 14:33 +0300, Vladimir Kondratiev wrote:
> > + * @NL80211_ATTR_4WAY_HANDSHAKE_OFFLOAD_STA: This is a flag that
> > indicates to + *	WPA supplicant that 4-way handshake has been offloaded
> > to the firmware + *	in the STA mode.
> > + *	In this case, WPA supplicant will provide driver with PSK for
> > + *	connect()
> > + *
> > + * @NL80211_ATTR_4WAY_HANDSHAKE_OFFLOAD_AP: This is a flag that indicates
> > to + *	WPA supplicant that 4-way handshake has been offloaded to the
> > firmware + *	in the AP mode.
> > + *	In this case, WPA supplicant will provide driver with PSK for
> > + *	start_ap()
> 
> I think you should use the nl80211 driver flags, not extra attributes
> here.

I thought I need to use same approach as for other flags. All other use bit in 
wiphy.flags and NL80211_ATTR_xxx. And reason is simple - in the NL80211, it is 
enum, while for the driver one need to reserve a bit. This is how other flags 
are dealt with:

	if ((dev->wiphy.flags & WIPHY_FLAG_IBSS_RSN) &&
	    nla_put_flag(msg, NL80211_ATTR_SUPPORT_IBSS_RSN))
		goto nla_put_failure;
	if ((dev->wiphy.flags & WIPHY_FLAG_MESH_AUTH) &&
	    nla_put_flag(msg, NL80211_ATTR_SUPPORT_MESH_AUTH))
		goto nla_put_failure;
	if ((dev->wiphy.flags & WIPHY_FLAG_AP_UAPSD) &&
	    nla_put_flag(msg, NL80211_ATTR_SUPPORT_AP_UAPSD))
		goto nla_put_failure;
	if ((dev->wiphy.flags & WIPHY_FLAG_SUPPORTS_FW_ROAM) &&
	    nla_put_flag(msg, NL80211_ATTR_ROAM_SUPPORT))
		goto nla_put_failure;
	if ((dev->wiphy.flags & WIPHY_FLAG_SUPPORTS_TDLS) &&
	    nla_put_flag(msg, NL80211_ATTR_TDLS_SUPPORT))
		goto nla_put_failure;
	if ((dev->wiphy.flags & WIPHY_FLAG_TDLS_EXTERNAL_SETUP) &&
	    nla_put_flag(msg, NL80211_ATTR_TDLS_EXTERNAL_SETUP))
		goto nla_put_failure;
	if ((dev->wiphy.flags & WIPHY_FLAG_4WAY_HANDSHAKE_OFFLOAD_STA) &&
	    nla_put_flag(msg, NL80211_ATTR_4WAY_HANDSHAKE_OFFLOAD_STA))
		goto nla_put_failure;

> 
> And the descriptions (and flag checking!) should make it clear that it
> is only supported with the connect() API, not with the auth/assoc APIs.
> 
> > + * @WIPHY_FLAG_4WAY_HANDSHAKE_OFFLOAD: Device supports 4-way handshake
> > offload.
> Use nl80211 flag directly. Also, docs are wrong:
> > +	WIPHY_FLAG_4WAY_HANDSHAKE_OFFLOAD_STA	= BIT(22),
> > +	WIPHY_FLAG_4WAY_HANDSHAKE_OFFLOAD_AP	= BIT(23),
> 
> Please also add validation that these flags are specified only when the
> correct APIs (connect/start_ap) are supported.

Agree, will add both doc and validation.

I want to do some more work exploring how this offload serves in real life, 
will submit when (if?) it will be ready.

Thanks, Vladimir.

Re: [PATCH v1] cfg80211: Support for 4-way handshake offloading for WPA2-Personal

[Johannes Berg]

On Thu, 2012-08-23 at 18:54 +0300, Vladimir Kondratiev wrote:

> > > + * @NL80211_ATTR_4WAY_HANDSHAKE_OFFLOAD_AP: This is a flag that indicates
> > > to + *	WPA supplicant that 4-way handshake has been offloaded to the
> > > firmware + *	in the AP mode.
> > > + *	In this case, WPA supplicant will provide driver with PSK for
> > > + *	start_ap()
> > 
> > I think you should use the nl80211 driver flags, not extra attributes
> > here.
> 
> I thought I need to use same approach as for other flags. All other use bit in 
> wiphy.flags and NL80211_ATTR_xxx. And reason is simple - in the NL80211, it is 
> enum, while for the driver one need to reserve a bit. This is how other flags 
> are dealt with:
> 
> 	if ((dev->wiphy.flags & WIPHY_FLAG_IBSS_RSN) &&
> 	    nla_put_flag(msg, NL80211_ATTR_SUPPORT_IBSS_RSN))
> 		goto nla_put_failure;

Yes, but we abandoned this approach later, in favour of the nl80211
feature flags.

> I want to do some more work exploring how this offload serves in real life, 
> will submit when (if?) it will be ready.

Ok, sounds good!

johannes

Re: [PATCH v1] cfg80211: Support for 4-way handshake offloading for WPA2-Personal

[Johannes Berg]

On Sun, 2012-08-26 at 10:11 +0300, Vladimir Kondratiev wrote:

> > >       if ((dev->wiphy.flags & WIPHY_FLAG_IBSS_RSN) &&
> > >           nla_put_flag(msg, NL80211_ATTR_SUPPORT_IBSS_RSN))
> > >               goto nla_put_failure;
> > 
> > Yes, but we abandoned this approach later, in favour of the nl80211
> > feature flags.
> 
> Good. Will re-implement this way.
> Could you please show an example that I can follow?

well, look at the feature flags.

enum nl80211_feature_flags

johannes

Scalable approach for nl80211_feature_flags

[Vladimir Kondratiev]

Hi,

There is 'new' approach for specifying various wifi driver flags,
using enum nl80211_feature_flags and wiphy.features.

Problem is, wiphy.features is u32, i.e. it is not scalable
beyond 32 flags.

I propose to re-define 'features' approach - convert it to
use 'bitmap' API like DECLARE_BITMAP for the 'features' and
use bit numbers rather then raw values in the
enum nl80211_feature_flags. Last value will be defined like
NL80211_FEATURE_MAX, and 'features' will auto-size using
DECLARE_BITMAP(features, NL80211_FEATURE_MAX);

Then, user space tools need to be modified as well.

If the direction looks correct, I'll go ahead to prepare patch.

Thanks, Vladimir.

Scalable approach for nl80211_feature_flags

[Vladimir Kondratiev]

Hi,

There is 'new' approach for specifying various wifi driver flags,
using enum nl80211_feature_flags and wiphy.features.

Problem is, wiphy.features is u32, i.e. it is not scalable
beyond 32 flags.

I propose to re-define 'features' approach - convert it to
use 'bitmap' API like DECLARE_BITMAP for the 'features' and
use bit numbers rather then raw values in the
enum nl80211_feature_flags. Last value will be defined like
NL80211_FEATURE_MAX, and 'features' will auto-size using
DECLARE_BITMAP(features, NL80211_FEATURE_MAX);

Then, user space tools need to be modified as well.

If the direction looks correct, I'll go ahead to prepare patch.

Thanks, Vladimir.

Re: Scalable approach for nl80211_feature_flags

[Kalle Valo]

Vladimir Kondratiev <qca_vkondrat@qca.qualcomm.com> writes:

> There is 'new' approach for specifying various wifi driver flags,
> using enum nl80211_feature_flags and wiphy.features.
>
> Problem is, wiphy.features is u32, i.e. it is not scalable
> beyond 32 flags.

And currently we have used 4 out of 32. During the 10 months it has
existed we have added four new flags, which makes it a rate of 2,5
months per flag. Based on this it takes over five years to fill
that u32. So I'm not really worried about that right now.

> I propose to re-define 'features' approach - convert it to
> use 'bitmap' API like DECLARE_BITMAP for the 'features' and
> use bit numbers rather then raw values in the
> enum nl80211_feature_flags. Last value will be defined like
> NL80211_FEATURE_MAX, and 'features' will auto-size using
> DECLARE_BITMAP(features, NL80211_FEATURE_MAX);
>
> Then, user space tools need to be modified as well.

Please take into account that the kernel needs to be backwards
compatible and you cannot just change an existing nl80211 attribute to
something else. IMHO this isn't worth the trouble, we manage with the
u32 just fine for now.

-- 
Kalle Valo