Re: Path for fixed channel issue in aircrack-ng suite [V2]

[Richard Farina <sidhayn@gmail.com>]

Johannes Berg wrote:
> On Tue, 2010-06-01 at 21:28 +0300, Maxim Levitsky wrote:
>
>   
>>     wireless: allow to retrieve the channel set on monitor interface
>>     
>>     This will allow to preserve compatibility with userspace
>>     
>>     Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com>
>>
>> diff --git a/net/wireless/chan.c b/net/wireless/chan.c
>> index b01a6f6..09d979b 100644
>> --- a/net/wireless/chan.c
>> +++ b/net/wireless/chan.c
>> @@ -49,9 +49,12 @@ int cfg80211_set_freq(struct cfg80211_registered_device *rdev,
>>  {
>>  	struct ieee80211_channel *chan;
>>  	int result;
>> +	struct wireless_dev *mon_dev = NULL;
>>  
>> -	if (wdev && wdev->iftype == NL80211_IFTYPE_MONITOR)
>> +	if (wdev && wdev->iftype == NL80211_IFTYPE_MONITOR) {
>> +		mon_dev = wdev;
>>  		wdev = NULL;
>> +	}
>>  
>>  	if (wdev) {
>>  		ASSERT_WDEV_LOCK(wdev);
>> @@ -76,5 +79,8 @@ int cfg80211_set_freq(struct cfg80211_registered_device *rdev,
>>  	if (wdev)
>>  		wdev->channel = chan;
>>  
>> +	if (mon_dev)
>> +		mon_dev->channel = chan;
>> +
>>     
>
> This won't quite work. monitor interfaces are always slaves in the sense
> that their channel setting never takes precedence over anything, so if
> you add another interface and do something there, the hardware will
> happily channel switch away from the monitor channel, but it will still
> report the old channel here that you set.
>
> I have no idea how to _properly_ fix this though, since eventually we'll
> have a situation where you can have multiple interfaces active on
> different channels, so that monitors don't have a fixed channel anyway.
>
> Maybe this patch is sufficient since it works in the case people care
> about when they _only_ have a monitor interface, but I think it'd be
> nicer if it wouldn't report anything in the other cases.
>
>   
Is this a NACK or a "I wish there was a better way to do this but I'll 
allow it until a better way if found"?

-Rick

> johannes
>
>
>