From 0c7dc45d21de6ae212b5ccb7cdff5beff795ccf0 Mon Sep 17 00:00:00 2001 From: "Luis R. Rodriguez" Date: Wed, 7 Jan 2009 17:43:36 -0800 Subject: [PATCH] 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: Luis R. Rodriguez Acked-by: Johannes Berg Signed-off-by: John W. Linville --- net/wireless/reg.c | 82 ++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 79 insertions(+), 3 deletions(-) diff --git a/net/wireless/reg.c b/net/wireless/reg.c index af805b0e1579..5f6d20d98eeb 100644 --- a/net/wireless/reg.c +++ b/net/wireless/reg.c @@ -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, ®_rule); if (r) { - flags |= IEEE80211_CHAN_DISABLED; - chan->flags = flags; + /* 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; } -- 2.20.1