Commit 0c7dc45d authored by Luis R. Rodriguez's avatar Luis R. Rodriguez Committed by John W. Linville
Browse files

cfg80211: Fix regression with 11d on bands 

This fixes a regression on disallowing bands introduced with the new
802.11d support. The issue is that IEEE-802.11 allows APs to send
a subset of what a country regulatory domain defines. This was clarified
in this document:

http://tinyurl.com/11d-clarification



As such it is possible, and this is what is done in practice, that a
single band 2.4 GHz AP will only send 2.4 GHz band regulatory information
through the 802.11 country information element and then the current
intersection with what CRDA provided yields a regulatory domain with
no 5 GHz information -- even though that country may actually allow
5 GHz operation. We correct this by only applying the intersection rules
on a channel if the the intersection yields a regulatory rule on the
same band the channel is on.

Signed-off-by: default avatarLuis R. Rodriguez <lrodriguez@atheros.com>
Acked-by: default avatarJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
parent a92a3ce7

net/wireless/reg.c

+79 −3
Original line number Diff line number Diff line
@@ -421,6 +421,31 @@ static u32 freq_max_bandwidth(const struct ieee80211_freq_range *freq_range, 
	return 0;

}



/**

 * freq_in_rule_band - tells us if a frequency is in a frequency band

 * @freq_range: frequency rule we want to query

 * @freq_khz: frequency we are inquiring about

 *

 * This lets us know if a specific frequency rule is or is not relevant to

 * a specific frequency's band. Bands are device specific and artificial

 * definitions (the "2.4 GHz band" and the "5 GHz band"), however it is

 * safe for now to assume that a frequency rule should not be part of a

 * frequency's band if the start freq or end freq are off by more than 2 GHz.

 * This resolution can be lowered and should be considered as we add

 * regulatory rule support for other "bands".

 **/

static bool freq_in_rule_band(const struct ieee80211_freq_range *freq_range,

	u32 freq_khz)

{

#define ONE_GHZ_IN_KHZ	1000000

	if (abs(freq_khz - freq_range->start_freq_khz) <= (2 * ONE_GHZ_IN_KHZ))

		return true;

	if (abs(freq_khz - freq_range->end_freq_khz) <= (2 * ONE_GHZ_IN_KHZ))

		return true;

	return false;

#undef ONE_GHZ_IN_KHZ

}



/* Converts a country IE to a regulatory domain. A regulatory domain

 * structure has a lot of information which the IE doesn't yet have,

 * so for the other values we use upper max values as we will intersect
@@ -748,12 +773,23 @@ static u32 map_regdom_flags(u32 rd_flags) 
 * 	this value to the maximum allowed bandwidth.

 * @reg_rule: the regulatory rule which we have for this frequency

 *

 * Use this function to get the regulatory rule for a specific frequency.

 * Use this function to get the regulatory rule for a specific frequency on

 * a given wireless device. If the device has a specific regulatory domain

 * it wants to follow we respect that unless a country IE has been received

 * and processed already.

 *

 * Returns 0 if it was able to find a valid regulatory rule which does

 * apply to the given center_freq otherwise it returns non-zero. It will

 * also return -ERANGE if we determine the given center_freq does not even have

 * a regulatory rule for a frequency range in the center_freq's band. See

 * freq_in_rule_band() for our current definition of a band -- this is purely

 * subjective and right now its 802.11 specific.

 */

static int freq_reg_info(u32 center_freq, u32 *bandwidth,

			 const struct ieee80211_reg_rule **reg_rule)

{

	int i;

	bool band_rule_found = false;

	u32 max_bandwidth = 0;



	if (!cfg80211_regdomain)
@@ -767,7 +803,15 @@ static int freq_reg_info(u32 center_freq, u32 *bandwidth, 
		rr = &cfg80211_regdomain->reg_rules[i];

		fr = &rr->freq_range;

		pr = &rr->power_rule;



		/* We only need to know if one frequency rule was

		 * was in center_freq's band, that's enough, so lets

		 * not overwrite it once found */

		if (!band_rule_found)

			band_rule_found = freq_in_rule_band(fr, center_freq);



		max_bandwidth = freq_max_bandwidth(fr, center_freq);



		if (max_bandwidth && *bandwidth <= max_bandwidth) {

			*reg_rule = rr;

			*bandwidth = max_bandwidth;
@@ -775,6 +819,9 @@ static int freq_reg_info(u32 center_freq, u32 *bandwidth, 
		}

	}



	if (!band_rule_found)

		return -ERANGE;



	return !max_bandwidth;

}
@@ -799,8 +846,37 @@ static void handle_channel(struct wiphy *wiphy, enum ieee80211_band band, 
		&max_bandwidth, &reg_rule);



	if (r) {

		/* This means no regulatory rule was found in the country IE

		 * with a frequency range on the center_freq's band, since

		 * IEEE-802.11 allows for a country IE to have a subset of the

		 * regulatory information provided in a country we ignore

		 * disabling the channel unless at least one reg rule was

		 * found on the center_freq's band. For details see this

		 * clarification:

		 *

		 * http://tinyurl.com/11d-clarification

		 */

		if (r == -ERANGE &&

		    last_request->initiator == REGDOM_SET_BY_COUNTRY_IE) {

#ifdef CONFIG_CFG80211_REG_DEBUG

			printk(KERN_DEBUG "cfg80211: Leaving channel %d MHz "

				"intact on %s - no rule found in band on "

				"Country IE\n",

				chan->center_freq, wiphy_name(wiphy));

#endif

		} else {

		/* In this case we know the country IE has at least one reg rule

		 * for the band so we respect its band definitions */

#ifdef CONFIG_CFG80211_REG_DEBUG

			if (last_request->initiator == REGDOM_SET_BY_COUNTRY_IE)

				printk(KERN_DEBUG "cfg80211: Disabling "

					"channel %d MHz on %s due to "

					"Country IE\n",

					chan->center_freq, wiphy_name(wiphy));

#endif

			flags |= IEEE80211_CHAN_DISABLED;

			chan->flags = flags;

		}

		return;

	}

CRA Git | Maintained and supported by SUSTech CRA and CCSE