Re: [RFC v4] cfg80211: Android P2P-Device workaround

Sreenath <sreenats@xxxxxxxxxxxx> · Tue, 30 Apr 2013 19:08:27 +0530

Hello Johannes,

As per this patch, the dummy 'p2p0' interface will be created only if 
new interface creation request is for interface type - 
NL80211_IFTYPE_P2P_DEVICE. Does that mean that this P2P hack will work 
only with wpa_supplicant patches submitted by David Spinadel or similar 
changes have to be done in wpa_supplicant? Because with current version 
of wpa_supplicant there won't be any interface creation request for 
NL80211_IFTYPE_P2P_DEVICE as the interface type.

Moreover with David Spinadel's wpa_supplicant patches, the dummy 
interface name will be 'p2p-dev-<WLAN_PRIMARY_IF_NAME>' not 'p2p0'. So 
please provide more clarity on how this patch can be tested.

Regards,
Sreenath

On 04/29/2013 05:56 PM, Johannes Berg wrote:
From: Johannes Berg <johannes.berg@xxxxxxxxx>

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@xxxxxxxxx>
---
  include/net/cfg80211.h |   4 ++
  net/wireless/Kconfig   |   7 +++
  net/wireless/Makefile  |   1 +
  net/wireless/android.c | 147 +++++++++++++++++++++++++++++++++++++++++++++++++
  net/wireless/core.c    |  14 +++++
  net/wireless/core.h    |   6 ++
  net/wireless/nl80211.c |  63 +++++++++++++++++++++
  7 files changed, 242 insertions(+)
  create mode 100644 net/wireless/android.c

diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index 87f7e1d..6e312ef 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -2924,6 +2924,10 @@ struct wireless_dev {
  		bool prev_bssid_valid;
  	} wext;
  #endif
+
+#ifdef CONFIG_CFG80211_ANDROID_P2P_HACK
+	struct net_device *p2pdev;
+#endif
  };
  
  static inline u8 *wdev_address(struct wireless_dev *wdev)
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..e24c764
--- /dev/null
+++ b/net/wireless/android.c
@@ -0,0 +1,147 @@
+/******************************************************************************
+ *
+ * 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@xxxxxxxxxxxxxxx>
+ * Intel Corporation, 5200 N.E. Elam Young Parkway, Hillsboro, OR 97124-6497
+ *
+ * Author: Johannes Berg <johannes.berg@xxxxxxxxx>
+ *
+ *****************************************************************************/
+#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->p2pdev))
+		return;
+
+	wdev->p2pdev = alloc_netdev(0, name, cfg80211_android_p2pdev_setup);
+	if (WARN(!wdev->p2pdev,
+		 "Failed to allocate P2P-Device netdev, things will fail!\n"))
+		return;
+
+	memcpy(wdev->p2pdev->dev_addr, wdev->address, ETH_ALEN);
+	wdev->p2pdev->ieee80211_ptr = wdev;
+
+	if (WARN(register_netdevice(wdev->p2pdev),
+		 "Failed to register P2P-Device netdev, things will fail!\n")) {
+		free_netdev(wdev->p2pdev);
+		return;
+	}
+
+	if (sysfs_create_link(&wdev->p2pdev->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->p2pdev)
+		return;
+
+	dev_close(wdev->p2pdev);
+	wdev->p2pdev->ieee80211_ptr = NULL;
+	unregister_netdevice(wdev->p2pdev);
+	wdev->p2pdev = NULL;
+}
diff --git a/net/wireless/core.c b/net/wireless/core.c
index 84c9ad7..59da6df 100644
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -170,6 +170,12 @@ int cfg80211_switch_netns(struct cfg80211_registered_device *rdev,
  		return -EOPNOTSUPP;
  
  	list_for_each_entry(wdev, &rdev->wdev_list, list) {
+#ifdef CONFIG_CFG80211_ANDROID_P2P_HACK
+		if (wdev->iftype == NL80211_IFTYPE_P2P_DEVICE) {
+			err = -EBUSY;
+			break;
+		}
+#endif
  		if (!wdev->netdev)
  			continue;
  		wdev->netdev->features &= ~NETIF_F_NETNS_LOCAL;
@@ -818,6 +824,9 @@ 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);
@@ -898,6 +907,11 @@ 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..0cc74d5 100644
--- a/net/wireless/core.h
+++ b/net/wireless/core.h
@@ -522,4 +522,10 @@ 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
+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..732a29b 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -87,6 +87,13 @@ __cfg80211_wdev_from_attrs(struct net *netns, struct nlattr **attrs)
  				result = wdev;
  				break;
  			}
+#ifdef CONFIG_CFG80211_ANDROID_P2P_HACK
+			if (have_ifidx && wdev->p2pdev &&
+			    wdev->p2pdev->ifindex == ifidx) {
+				result = wdev;
+				break;
+			}
+#endif
  			if (have_wdev_id && wdev->identifier == (u32)wdev_id) {
  				result = wdev;
  				break;
@@ -2350,6 +2357,14 @@ 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 +2494,10 @@ 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);
@@ -5624,6 +5643,11 @@ static int nl80211_send_bss(struct sk_buff *msg, struct netlink_callback *cb,
  	if (wdev->netdev &&
  	    nla_put_u32(msg, NL80211_ATTR_IFINDEX, wdev->netdev->ifindex))
  		goto nla_put_failure;
+#ifdef CONFIG_CFG80211_ANDROID_P2P_HACK
+	if (wdev->p2pdev &&
+	    nla_put_u32(msg, NL80211_ATTR_IFINDEX, wdev->p2pdev->ifindex))
+		goto nla_put_failure;
+#endif
  	if (nla_put_u64(msg, NL80211_ATTR_WDEV, wdev_id(wdev)))
  		goto nla_put_failure;
  
@@ -8183,6 +8207,11 @@ 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->p2pdev && dev_open(wdev->p2pdev));
+#endif
+
  	mutex_lock(&rdev->devlist_mtx);
  	rdev->opencount++;
  	mutex_unlock(&rdev->devlist_mtx);
@@ -8207,6 +8236,10 @@ 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->p2pdev && dev_close(wdev->p2pdev));
+#endif
+
  	return 0;
  }
  
@@ -8361,6 +8394,12 @@ 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 = wdev->p2pdev;
+#endif
+
  		if (ops->internal_flags & NL80211_FLAG_NEED_NETDEV) {
  			if (!dev) {
  				mutex_unlock(&cfg80211_mutex);
@@ -9118,6 +9157,12 @@ static int nl80211_send_scan_msg(struct sk_buff *msg,
  	    nla_put_u64(msg, NL80211_ATTR_WDEV, wdev_id(wdev)))
  		goto nla_put_failure;
  
+#ifdef CONFIG_CFG80211_ANDROID_P2P_HACK
+	if (wdev->p2pdev &&
+	    nla_put_u32(msg, NL80211_ATTR_IFINDEX, wdev->p2pdev->ifindex))
+		goto nla_put_failure;
+#endif
+
  	/* ignore errors and send incomplete event anyway */
  	nl80211_add_scan_req(msg, rdev);
  
@@ -9764,6 +9809,12 @@ static void nl80211_send_remain_on_chan_event(
  	    nla_put_u64(msg, NL80211_ATTR_COOKIE, cookie))
  		goto nla_put_failure;
  
+#ifdef CONFIG_CFG80211_ANDROID_P2P_HACK
+	if (wdev->p2pdev &&
+	    nla_put_u32(msg, NL80211_ATTR_IFINDEX, wdev->p2pdev->ifindex))
+		goto nla_put_failure;
+#endif
+
  	if (cmd == NL80211_CMD_REMAIN_ON_CHANNEL &&
  	    nla_put_u32(msg, NL80211_ATTR_DURATION, duration))
  		goto nla_put_failure;
@@ -10014,6 +10065,12 @@ int nl80211_send_mgmt(struct cfg80211_registered_device *rdev,
  	    nla_put(msg, NL80211_ATTR_FRAME, len, buf))
  		goto nla_put_failure;
  
+#ifdef CONFIG_CFG80211_ANDROID_P2P_HACK
+	if (wdev->p2pdev &&
+	    nla_put_u32(msg, NL80211_ATTR_IFINDEX, wdev->p2pdev->ifindex))
+		goto nla_put_failure;
+#endif
+
  	genlmsg_end(msg, hdr);
  
  	return genlmsg_unicast(wiphy_net(&rdev->wiphy), msg, nlportid);
@@ -10053,6 +10110,12 @@ void cfg80211_mgmt_tx_status(struct wireless_dev *wdev, u64 cookie,
  	    (ack && nla_put_flag(msg, NL80211_ATTR_ACK)))
  		goto nla_put_failure;
  
+#ifdef CONFIG_CFG80211_ANDROID_P2P_HACK
+	if (wdev->p2pdev &&
+	    nla_put_u32(msg, NL80211_ATTR_IFINDEX, wdev->p2pdev->ifindex))
+		goto nla_put_failure;
+#endif
+
  	genlmsg_end(msg, hdr);
  
  	genlmsg_multicast(msg, 0, nl80211_mlme_mcgrp.id, gfp);


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