mac80211: correct wext transmit power handler

Wext makes no assumptions about the contents of
data->txpower.fixed and data->txpower.value when
data->txpower.disabled is set, so do not update
the user-requested power level while disabling.

Also, when wext configures a really _fixed_ power
output [1], we should reject it instead of limiting it
to the regulatory constraint. If the user wants to set
a _limit_ [2] then we should honour that.

[1] iwconfig wlan0 txpower 20dBm fixed
[2] iwconfig wlan0 txpower 10dBm

This fixes
http://www.intellinuxwireless.org/bugzilla/show_bug.cgi?id=1942

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

2 files changed, 34 insertions, 9 deletions

diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index a6f1d8a869bc..fbcbed6cad01 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -258,7 +258,7 @@ int ieee80211_hw_config(struct ieee80211_local *local, u32 changed)
                         (chan->max_power - local->power_constr_level) :
                         chan->max_power;
 
-        if (local->user_power_level)
+        if (local->user_power_level >= 0)
                 power = min(power, local->user_power_level);
 
         if (local->hw.conf.power_level != power) {
diff --git a/net/mac80211/wext.c b/net/mac80211/wext.c
index deb4ecec122a..ce9115c18152 100644
--- a/net/mac80211/wext.c
+++ b/net/mac80211/wext.c
@@ -417,6 +417,7 @@ static int ieee80211_ioctl_siwtxpower(struct net_device *dev,
 {
         struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
         struct ieee80211_channel* chan = local->hw.conf.channel;
+        bool reconf = false;
         u32 reconf_flags = 0;
         int new_power_level;
 
@@ -427,14 +428,38 @@ static int ieee80211_ioctl_siwtxpower(struct net_device *dev,
         if (!chan)
                 return -EINVAL;
 
-        if (data->txpower.fixed)
-                new_power_level = min(data->txpower.value, chan->max_power);
-        else /* Automatic power level setting */
-                new_power_level = chan->max_power;
+        /* only change when not disabling */
+        if (!data->txpower.disabled) {
+                if (data->txpower.fixed) {
+                        if (data->txpower.value < 0)
+                                return -EINVAL;
+                        new_power_level = data->txpower.value;
+                        /*
+                         * Debatable, but we cannot do a fixed power
+                         * level above the regulatory constraint.
+                         * Use "iwconfig wlan0 txpower 15dBm" instead.
+                         */
+                        if (new_power_level > chan->max_power)
+                                return -EINVAL;
+                } else {
+                        /*
+                         * Automatic power level setting, max being the value
+                         * passed in from userland.
+                         */
+                        if (data->txpower.value < 0)
+                                new_power_level = -1;
+                        else
+                                new_power_level = data->txpower.value;
+                }
+
+                reconf = true;
 
-        local->user_power_level = new_power_level;
-        if (local->hw.conf.power_level != new_power_level)
-                reconf_flags |= IEEE80211_CONF_CHANGE_POWER;
+                /*
+                 * ieee80211_hw_config() will limit to the channel's
+                 * max power and possibly power constraint from AP.
+                 */
+                local->user_power_level = new_power_level;
+        }
 
         if (local->hw.conf.radio_enabled != !(data->txpower.disabled)) {
                 local->hw.conf.radio_enabled = !(data->txpower.disabled);
@@ -442,7 +467,7 @@ static int ieee80211_ioctl_siwtxpower(struct net_device *dev,
                 ieee80211_led_radio(local, local->hw.conf.radio_enabled);
         }
 
-        if (reconf_flags)
+        if (reconf || reconf_flags)
                 ieee80211_hw_config(local, reconf_flags);
 
         return 0;