[RFC v2] cfg80211: Android P2P-Device workaround

[RFC v2] cfg80211: Android P2P-Device workaround

[Johannes Berg]

From: Johannes Berg <johannes.berg@intel.com>

Android requires a "p2p0" netdev to exist for P2P Device
functionality, and will even set it "UP" to start the P2P
Device functionality.

This is a hack to provide it so not only is Android happy
but also the current version of wpa_supplicant can work
with P2P-Device functionality without needing changes to
support the P2P-Device commands, just a little bit to not
attempt to change the interface type to station.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
---
 net/wireless/Kconfig   |   7 +++
 net/wireless/Makefile  |   1 +
 net/wireless/android.c | 149 +++++++++++++++++++++++++++++++++++++++++++++++++
 net/wireless/core.c    |  15 ++++-
 net/wireless/core.h    |   7 +++
 net/wireless/nl80211.c |  31 ++++++++++
 6 files changed, 209 insertions(+), 1 deletion(-)
 create mode 100644 net/wireless/android.c

diff --git a/net/wireless/Kconfig b/net/wireless/Kconfig
index 16d08b3..7c2981c 100644
--- a/net/wireless/Kconfig
+++ b/net/wireless/Kconfig
@@ -139,6 +139,13 @@ config CFG80211_WEXT
 	  Enable this option if you need old userspace for wireless
 	  extensions with cfg80211-based drivers.
 
+config CFG80211_ANDROID_P2P_HACK
+	bool "Android P2P netdevice hack"
+	depends on CFG80211
+	depends on !CFG80211_WEXT
+	help
+	  Enable this option for Android P2P w/ P2P Device.
+
 config LIB80211
 	tristate
 	default n
diff --git a/net/wireless/Makefile b/net/wireless/Makefile
index a761670..2800e67 100644
--- a/net/wireless/Makefile
+++ b/net/wireless/Makefile
@@ -14,6 +14,7 @@ cfg80211-y += mlme.o ibss.o sme.o chan.o ethtool.o mesh.o ap.o trace.o
 cfg80211-$(CONFIG_CFG80211_DEBUGFS) += debugfs.o
 cfg80211-$(CONFIG_CFG80211_WEXT) += wext-compat.o wext-sme.o
 cfg80211-$(CONFIG_CFG80211_INTERNAL_REGDB) += regdb.o
+cfg80211-$(CONFIG_CFG80211_ANDROID_P2P_HACK) += android.o
 
 CFLAGS_trace.o := -I$(src)
 
diff --git a/net/wireless/android.c b/net/wireless/android.c
new file mode 100644
index 0000000..81aeb26
--- /dev/null
+++ b/net/wireless/android.c
@@ -0,0 +1,149 @@
+/******************************************************************************
+ *
+ * This file is provided under the GPLv2 license.
+ *
+ * GPL LICENSE SUMMARY
+ *
+ * Copyright(c) 2013 Intel Corporation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110,
+ * USA
+ *
+ * The full GNU General Public License is included in this distribution
+ * in the file called COPYING.
+ *
+ * Contact Information:
+ *  Intel Linux Wireless <ilw@linux.intel.com>
+ * Intel Corporation, 5200 N.E. Elam Young Parkway, Hillsboro, OR 97124-6497
+ *
+ * Author: Johannes Berg <johannes.berg@intel.com>
+ *
+ *****************************************************************************/
+#include <linux/kernel.h>
+#include <linux/netdevice.h>
+#include <linux/rtnetlink.h>
+#include <net/cfg80211.h>
+#include "core.h"
+#include "rdev-ops.h"
+
+static int cfg80211_android_p2pdev_open(struct net_device *dev)
+{
+	struct wireless_dev *wdev = dev->ieee80211_ptr;
+	struct cfg80211_registered_device *rdev = wiphy_to_dev(wdev->wiphy);
+	int err;
+
+	if (!rdev->ops->start_p2p_device)
+		return -EOPNOTSUPP;
+
+	if (wdev->iftype != NL80211_IFTYPE_P2P_DEVICE)
+		return -EOPNOTSUPP;
+
+	if (wdev->p2p_started)
+		return 0;
+
+	mutex_lock(&rdev->devlist_mtx);
+	err = cfg80211_can_add_interface(rdev, wdev->iftype);
+	mutex_unlock(&rdev->devlist_mtx);
+	if (err)
+		return err;
+
+	err = rdev_start_p2p_device(rdev, wdev);
+	if (err)
+		return err;
+
+	wdev->p2p_started = true;
+	mutex_lock(&rdev->devlist_mtx);
+	rdev->opencount++;
+	mutex_unlock(&rdev->devlist_mtx);
+
+	return 0;
+}
+
+static int cfg80211_android_p2pdev_stop(struct net_device *dev)
+{
+	struct wireless_dev *wdev = dev->ieee80211_ptr;
+	struct cfg80211_registered_device *rdev = wiphy_to_dev(wdev->wiphy);
+
+	if (!wdev->p2p_started)
+		return 0;
+
+	mutex_lock(&rdev->devlist_mtx);
+	mutex_lock(&rdev->sched_scan_mtx);
+	cfg80211_stop_p2p_device(rdev, wdev);
+	mutex_unlock(&rdev->sched_scan_mtx);
+	mutex_unlock(&rdev->devlist_mtx);
+
+	return 0;
+}
+
+static netdev_tx_t cfg80211_android_p2pdev_start_xmit(struct sk_buff *skb,
+						      struct net_device *dev)
+{
+	dev_kfree_skb(skb);
+	return NETDEV_TX_OK;
+}
+
+static const struct net_device_ops cfg80211_android_p2pdev_ops = {
+	.ndo_open = cfg80211_android_p2pdev_open,
+	.ndo_stop = cfg80211_android_p2pdev_stop,
+	.ndo_start_xmit = cfg80211_android_p2pdev_start_xmit,
+};
+
+static void cfg80211_android_p2pdev_setup(struct net_device *dev)
+{
+	ether_setup(dev);
+	dev->features |= NETIF_F_NETNS_LOCAL;
+	dev->netdev_ops = &cfg80211_android_p2pdev_ops;
+	dev->destructor = free_netdev;
+}
+
+void cfg80211_android_create_p2p_device(struct wireless_dev *wdev,
+					const char *name)
+{
+	if (WARN_ON(wdev->netdev))
+		return;
+
+	wdev->netdev = alloc_netdev(0, name, cfg80211_android_p2pdev_setup);
+	if (WARN(!wdev->netdev,
+		 "Failed to allocate P2P-Device netdev, things will fail\n"))
+		return;
+
+	memcpy(wdev->netdev->dev_addr, wdev->address, ETH_ALEN);
+	wdev->netdev->ieee80211_ptr = wdev;
+
+	SET_NETDEV_DEVTYPE(wdev->netdev, &wiphy_type);
+
+	if (WARN(register_netdevice(wdev->netdev),
+		 "Failed to register P2P-Device netdev, things will fail!\n")) {
+		free_netdev(wdev->netdev);
+		return;
+	}
+
+	if (sysfs_create_link(&wdev->netdev->dev.kobj, &wdev->wiphy->dev.kobj,
+			      "phy80211")) {
+		pr_err("failed to add phy80211 symlink to netdev!\n");
+	}
+}
+
+void cfg80211_android_destroy_p2p_device(struct wireless_dev *wdev)
+{
+	ASSERT_RTNL();
+
+	if (!wdev->netdev)
+		return;
+
+	dev_close(wdev->netdev);
+	unregister_netdevice(wdev->netdev);
+	wdev->netdev = NULL;
+}
diff --git a/net/wireless/core.c b/net/wireless/core.c
index 84c9ad7..70859e1 100644
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -807,8 +807,10 @@ void cfg80211_unregister_wdev(struct wireless_dev *wdev)
 
 	ASSERT_RTNL();
 
+#ifndef CONFIG_CFG80211_ANDROID_P2P_HACK
 	if (WARN_ON(wdev->netdev))
 		return;
+#endif
 
 	mutex_lock(&rdev->devlist_mtx);
 	mutex_lock(&rdev->sched_scan_mtx);
@@ -818,6 +820,9 @@ void cfg80211_unregister_wdev(struct wireless_dev *wdev)
 	switch (wdev->iftype) {
 	case NL80211_IFTYPE_P2P_DEVICE:
 		cfg80211_stop_p2p_device(rdev, wdev);
+#ifdef CONFIG_CFG80211_ANDROID_P2P_HACK
+		cfg80211_android_destroy_p2p_device(wdev);
+#endif
 		break;
 	default:
 		WARN_ON_ONCE(1);
@@ -828,7 +833,10 @@ void cfg80211_unregister_wdev(struct wireless_dev *wdev)
 }
 EXPORT_SYMBOL(cfg80211_unregister_wdev);
 
-static struct device_type wiphy_type = {
+#ifndef CONFIG_CFG80211_ANDROID_P2P_HACK
+static
+#endif
+struct device_type wiphy_type = {
 	.name	= "wlan",
 };
 
@@ -898,6 +906,11 @@ static int cfg80211_netdev_notifier_call(struct notifier_block *nb,
 
 	WARN_ON(wdev->iftype == NL80211_IFTYPE_UNSPECIFIED);
 
+#ifdef CONFIG_CFG80211_ANDROID_P2P_HACK
+	if (wdev->iftype == NL80211_IFTYPE_P2P_DEVICE)
+		return NOTIFY_DONE;
+#endif
+
 	switch (state) {
 	case NETDEV_POST_INIT:
 		SET_NETDEV_DEVTYPE(dev, &wiphy_type);
diff --git a/net/wireless/core.h b/net/wireless/core.h
index fd35dae..91d5a97 100644
--- a/net/wireless/core.h
+++ b/net/wireless/core.h
@@ -522,4 +522,11 @@ void cfg80211_stop_p2p_device(struct cfg80211_registered_device *rdev,
 #define CFG80211_DEV_WARN_ON(cond)	({bool __r = (cond); __r; })
 #endif
 
+#ifdef CONFIG_CFG80211_ANDROID_P2P_HACK
+extern struct device_type wiphy_type;
+void cfg80211_android_create_p2p_device(struct wireless_dev *wdev,
+					const char *name);
+void cfg80211_android_destroy_p2p_device(struct wireless_dev *wdev);
+#endif
+
 #endif /* __NET_WIRELESS_CORE_H */
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index f687a8d..95ec1cd 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -2350,6 +2350,14 @@ static int nl80211_set_interface(struct sk_buff *skb, struct genl_info *info)
 			return -EINVAL;
 	}
 
+#ifdef CONFIG_CFG80211_ANDROID_P2P_HACK
+	if (otype == NL80211_IFTYPE_P2P_DEVICE) {
+		if (ntype == NL80211_IFTYPE_P2P_DEVICE)
+			return 0;
+		return -EINVAL;
+	}
+#endif
+
 	if (info->attrs[NL80211_ATTR_MESH_ID]) {
 		struct wireless_dev *wdev = dev->ieee80211_ptr;
 
@@ -2479,6 +2487,10 @@ static int nl80211_new_interface(struct sk_buff *skb, struct genl_info *info)
 		INIT_LIST_HEAD(&wdev->mgmt_registrations);
 		spin_lock_init(&wdev->mgmt_registrations_lock);
 
+#ifdef CONFIG_CFG80211_ANDROID_P2P_HACK
+		cfg80211_android_create_p2p_device(wdev,
+			nla_data(info->attrs[NL80211_ATTR_IFNAME]));
+#endif
 		mutex_lock(&rdev->devlist_mtx);
 		wdev->identifier = ++rdev->wdev_id;
 		list_add_rcu(&wdev->list, &rdev->wdev_list);
@@ -2513,6 +2525,10 @@ static int nl80211_del_interface(struct sk_buff *skb, struct genl_info *info)
 	 * since the wdev has been freed, unlike with a netdev where
 	 * we need the dev_put() for the netdev to really be freed.
 	 */
+#ifdef CONFIG_CFG80211_ANDROID_P2P_HACK
+	if (wdev->iftype == NL80211_IFTYPE_P2P_DEVICE)
+		info->user_ptr[1] = NULL;
+#endif
 	if (!wdev->netdev)
 		info->user_ptr[1] = NULL;
 
@@ -8183,6 +8199,11 @@ static int nl80211_start_p2p_device(struct sk_buff *skb, struct genl_info *info)
 		return err;
 
 	wdev->p2p_started = true;
+
+#ifdef CONFIG_CFG80211_ANDROID_P2P_HACK
+	WARN_ON(wdev->netdev && dev_open(wdev->netdev));
+#endif
+
 	mutex_lock(&rdev->devlist_mtx);
 	rdev->opencount++;
 	mutex_unlock(&rdev->devlist_mtx);
@@ -8207,6 +8228,10 @@ static int nl80211_stop_p2p_device(struct sk_buff *skb, struct genl_info *info)
 	mutex_unlock(&rdev->sched_scan_mtx);
 	mutex_unlock(&rdev->devlist_mtx);
 
+#ifdef CONFIG_CFG80211_ANDROID_P2P_HACK
+	WARN_ON(wdev->netdev && dev_close(wdev->netdev));
+#endif
+
 	return 0;
 }
 
@@ -8361,6 +8386,12 @@ static int nl80211_pre_doit(struct genl_ops *ops, struct sk_buff *skb,
 		dev = wdev->netdev;
 		rdev = wiphy_to_dev(wdev->wiphy);
 
+#ifdef CONFIG_CFG80211_ANDROID_P2P_HACK
+		if (wdev->iftype == NL80211_IFTYPE_P2P_DEVICE &&
+		    info->genlhdr->cmd != NL80211_CMD_SET_INTERFACE)
+			dev = NULL;
+#endif
+
 		if (ops->internal_flags & NL80211_FLAG_NEED_NETDEV) {
 			if (!dev) {
 				mutex_unlock(&cfg80211_mutex);
-- 
1.8.0

Re: [RFC v2] cfg80211: Android P2P-Device workaround

[Kalle Valo]

Johannes Berg <johannes@sipsolutions.net> writes:

> +#ifndef CONFIG_CFG80211_ANDROID_P2P_HACK
>  	if (WARN_ON(wdev->netdev))
>  		return;
> +#endif

With my favorite kernel macro, config_enabled(), you could get rid of
quite a lot of the ugly ifdefs.

-- 
Kalle Valo

Re: [RFC v2] cfg80211: Android P2P-Device workaround

[Johannes Berg]

On Wed, 2013-04-24 at 13:11 +0300, Kalle Valo wrote:
> Johannes Berg <johannes@sipsolutions.net> writes:
> 
> > +#ifndef CONFIG_CFG80211_ANDROID_P2P_HACK
> >  	if (WARN_ON(wdev->netdev))
> >  		return;
> > +#endif
> 
> With my favorite kernel macro, config_enabled(), you could get rid of
> quite a lot of the ugly ifdefs.

Yeah, but as long as this isn't going upstream I don't really want to
though since then it touches the code and is less obvious. Anyway we'll
see.

johannes

Re: [RFC v2] cfg80211: Android P2P-Device workaround

[Kalle Valo]

Johannes Berg <johannes@sipsolutions.net> writes:

> On Wed, 2013-04-24 at 13:11 +0300, Kalle Valo wrote:
>> Johannes Berg <johannes@sipsolutions.net> writes:
>> 
>> > +#ifndef CONFIG_CFG80211_ANDROID_P2P_HACK
>> >  	if (WARN_ON(wdev->netdev))
>> >  		return;
>> > +#endif
>> 
>> With my favorite kernel macro, config_enabled(), you could get rid of
>> quite a lot of the ugly ifdefs.
>
> Yeah, but as long as this isn't going upstream I don't really want to
> though since then it touches the code and is less obvious. Anyway we'll
> see.

Ah, makes send.

FWIW, I think we should push this, and other wireless Android support,
upstream. We should first get them to use upstream interfaces and then
start fixing the problematic areas one by one.

-- 
Kalle Valo

Re: [RFC v2] cfg80211: Android P2P-Device workaround

[Arend van Spriel]

On 04/24/2013 12:52 PM, Kalle Valo wrote:
> Johannes Berg <johannes@sipsolutions.net> writes:
>
>> On Wed, 2013-04-24 at 13:11 +0300, Kalle Valo wrote:
>>> Johannes Berg <johannes@sipsolutions.net> writes:
>>>
>>>> +#ifndef CONFIG_CFG80211_ANDROID_P2P_HACK
>>>>   	if (WARN_ON(wdev->netdev))
>>>>   		return;
>>>> +#endif
>>>
>>> With my favorite kernel macro, config_enabled(), you could get rid of
>>> quite a lot of the ugly ifdefs.
>>
>> Yeah, but as long as this isn't going upstream I don't really want to
>> though since then it touches the code and is less obvious. Anyway we'll
>> see.
>
> Ah, makes send.
>
> FWIW, I think we should push this, and other wireless Android support,
> upstream. We should first get them to use upstream interfaces and then
> start fixing the problematic areas one by one.

I agree. Another big hurdle I see are the android driver private ioctls. 
Do you have a good knowledge about those? I think some of those already 
have a nl80211 equivalent.

Maybe it would be good to update twiki [1] on wireless.kernel.org with 
such information. It seems a bit outdated.

Regards,
Arend

[1] http://wireless.kernel.org/en/developers/Documentation/Android