[PATCH v2 4/6] cfg80211: check allowed channel type upon userspace requests

["Luis R. Rodriguez" <lrodriguez@atheros.com>]

Thanks to nl80211 userspace can be verify specific upon device
configuration. Before processing the request for the new HT40
channel types (HT40- or HT40+) we need to ensure we can use them
regulatory-wise. This wasn't required with wireless extensions as
specifying the channel type wasn't not available and configuration
was done towards the end implicitly upon association or reception
of beacons from the AP. For the new nl80211 we have to check this
when configuring the interfaces explicitly.

Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
---
 net/wireless/nl80211.c |   18 ++++++++++++++++++
 1 files changed, 18 insertions(+), 0 deletions(-)

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 53fe209..e03c9a2 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -426,6 +426,24 @@ static int nl80211_set_wiphy(struct sk_buff *skb, struct genl_info *info)
 		if (!chan || chan->flags & IEEE80211_CHAN_DISABLED)
 			goto bad_res;
 
+		if (channel_type == NL80211_CHAN_HT40MINUS ||
+		    channel_type == NL80211_CHAN_HT40PLUS)
+			if (chan->flags & IEEE80211_CHAN_NO_HT40)
+				goto bad_res;
+
+		if (channel_type == NL80211_CHAN_HT40MINUS &&
+		    (chan->flags & IEEE80211_CHAN_NO_HT40MINUS))
+			goto bad_res;
+		else if (channel_type == NL80211_CHAN_HT40PLUS &&
+			 (chan->flags & IEEE80211_CHAN_NO_HT40PLUS))
+			goto bad_res;
+
+		/*
+		 * At this point we know if that if HT40 was requested
+		 * we are allowed to use it and the extension channel
+		 * exists.
+		 */
+
 		if (channel_type == NL80211_CHAN_HT40MINUS)
 			sec_freq = freq - 20;
 		else if (channel_type == NL80211_CHAN_HT40PLUS)
-- 
1.6.0.6