nl80211: Parse channel type attribute in an ibss join request

Prepare cfg80211 for IBSS HT:
 * extend cfg80211 ibss struct with channel_type
 * Check if extension channel can be used
 * Export can_beacon_sec_chan for use in mac80211 (will be called
   from ibss.c later).
Signed-off-by: Alexander Simon <an.alexsimon@googlemail.com>
[siwu@hrz.tu-chemnitz.de: Updates]
* fix cfg80211_can_beacon_ext_chan comment
* remove implicit channel_type enum assumptions
* remove radar channel flags check
* add HT IBSS feature flag
* reword commit message
Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Signed-off-by: Mathias Kretschmer <mathias.kretschmer@fokus.fraunhofer.de>
Reviewed-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

include/linux/nl80211.h

@@ -2785,9 +2785,11 @@ enum nl80211_ap_sme_features {
  * @NL80211_FEATURE_SK_TX_STATUS: This driver supports reflecting back
  *	TX status to the socket error queue when requested with the
  *	socket option.
+ * @NL80211_FEATURE_HT_IBSS: This driver supports IBSS with HT datarates.
  */
 enum nl80211_feature_flags {
 	NL80211_FEATURE_SK_TX_STATUS	= 1 << 0,
+	NL80211_FEATURE_HT_IBSS		= 1 << 1,
 };
 
 /**

include/net/cfg80211.h

@@ -1149,6 +1149,7 @@ struct cfg80211_ibss_params {
 	u8 *ssid;
 	u8 *bssid;
 	struct ieee80211_channel *channel;
+	enum nl80211_channel_type channel_type;
 	u8 *ie;
 	u8 ssid_len, ie_len;
 	u16 beacon_interval;
@@ -3267,6 +3268,16 @@ void cfg80211_report_obss_beacon(struct wiphy *wiphy,
 				 const u8 *frame, size_t len,
 				 int freq, gfp_t gfp);
 
+/*
+ * cfg80211_can_beacon_sec_chan - test if ht40 on extension channel can be used
+ * @wiphy: the wiphy
+ * @chan: main channel
+ * @channel_type: HT mode
+ */
+int cfg80211_can_beacon_sec_chan(struct wiphy *wiphy,
+				 struct ieee80211_channel *chan,
+				 enum nl80211_channel_type channel_type);
+
 /* Logging, debugging and troubleshooting/diagnostic helpers. */
 
 /* wiphy_printk helpers, similar to dev_printk */

net/wireless/chan.c

@@ -6,6 +6,7 @@
  * Copyright 2009	Johannes Berg <johannes@sipsolutions.net>
  */
 
+#include <linux/export.h>
 #include <net/cfg80211.h>
 #include "core.h"
 
@@ -44,7 +45,7 @@ rdev_freq_to_chan(struct cfg80211_registered_device *rdev,
 	return chan;
 }
 
-static bool can_beacon_sec_chan(struct wiphy *wiphy,
+int cfg80211_can_beacon_sec_chan(struct wiphy *wiphy,
 				  struct ieee80211_channel *chan,
 				  enum nl80211_channel_type channel_type)
 {
@@ -75,6 +76,7 @@ static bool can_beacon_sec_chan(struct wiphy *wiphy,
 
 	return true;
 }
+EXPORT_SYMBOL(cfg80211_can_beacon_sec_chan);
 
 int cfg80211_set_freq(struct cfg80211_registered_device *rdev,
 		      struct wireless_dev *wdev, int freq,
@@ -109,7 +111,7 @@ int cfg80211_set_freq(struct cfg80211_registered_device *rdev,
 		switch (channel_type) {
 		case NL80211_CHAN_HT40PLUS:
 		case NL80211_CHAN_HT40MINUS:
-			if (!can_beacon_sec_chan(&rdev->wiphy, chan,
+			if (!cfg80211_can_beacon_sec_chan(&rdev->wiphy, chan,
 							  channel_type)) {
 				printk(KERN_DEBUG
 				       "cfg80211: Secondary channel not "

net/wireless/nl80211.c

@@ -4682,13 +4682,41 @@ static int nl80211_join_ibss(struct sk_buff *skb, struct genl_info *info)
 		ibss.ie_len = nla_len(info->attrs[NL80211_ATTR_IE]);
 	}
 
-	ibss.channel = ieee80211_get_channel(wiphy,
-		nla_get_u32(info->attrs[NL80211_ATTR_WIPHY_FREQ]));
+	if (info->attrs[NL80211_ATTR_WIPHY_CHANNEL_TYPE]) {
+		enum nl80211_channel_type channel_type;
+
+		channel_type = nla_get_u32(
+				info->attrs[NL80211_ATTR_WIPHY_CHANNEL_TYPE]);
+		if (channel_type != NL80211_CHAN_NO_HT &&
+		    channel_type != NL80211_CHAN_HT20 &&
+		    channel_type != NL80211_CHAN_HT40MINUS &&
+		    channel_type != NL80211_CHAN_HT40PLUS)
+			return -EINVAL;
+
+		if (channel_type != NL80211_CHAN_NO_HT &&
+		    !(wiphy->features & NL80211_FEATURE_HT_IBSS))
+			return -EINVAL;
+
+		ibss.channel_type = channel_type;
+	} else {
+		ibss.channel_type = NL80211_CHAN_NO_HT;
+	}
+
+	ibss.channel = rdev_freq_to_chan(rdev,
+		nla_get_u32(info->attrs[NL80211_ATTR_WIPHY_FREQ]),
+		ibss.channel_type);
 	if (!ibss.channel ||
 	    ibss.channel->flags & IEEE80211_CHAN_NO_IBSS ||
 	    ibss.channel->flags & IEEE80211_CHAN_DISABLED)
 		return -EINVAL;
 
+	/* Both channels should be able to initiate communication */
+	if ((ibss.channel_type == NL80211_CHAN_HT40PLUS ||
+	     ibss.channel_type == NL80211_CHAN_HT40MINUS) &&
+	    !cfg80211_can_beacon_sec_chan(&rdev->wiphy, ibss.channel,
+					  ibss.channel_type))
+		return -EINVAL;
+
 	ibss.channel_fixed = !!info->attrs[NL80211_ATTR_FREQ_FIXED];
 	ibss.privacy = !!info->attrs[NL80211_ATTR_PRIVACY];