[PATCH] mac80211: allow mgmt frame transmission on DFS channels

[PATCH] mac80211: allow mgmt frame transmission on DFS channels

[Lorenzo Bianconi]

Allow management frame injection on DFS channels if the channel has been CAC
checked and is available

Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi83@gmail.com>
---
 net/mac80211/tx.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 3456c04..edb1d3e 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -1694,8 +1694,10 @@ netdev_tx_t ieee80211_monitor_start_xmit(struct sk_buff *skb,
 	 * radar detection by itself. We can do that later by adding a
 	 * monitor flag interfaces used for AP support.
 	 */
-	if ((chan->flags & (IEEE80211_CHAN_NO_IBSS | IEEE80211_CHAN_RADAR |
-			    IEEE80211_CHAN_PASSIVE_SCAN)))
+	if (((chan->flags & (IEEE80211_CHAN_PASSIVE_SCAN |
+			     IEEE80211_CHAN_NO_IBSS))) ||
+	    ((chan->flags & IEEE80211_CHAN_RADAR) &&
+	     chan->dfs_state != NL80211_DFS_AVAILABLE))
 		goto fail_rcu;
 
 	ieee80211_xmit(sdata, skb, chan->band);
-- 
1.8.1.2

Re: [PATCH] mac80211: allow mgmt frame transmission on DFS channels

[Johannes Berg]

On Mon, 2013-09-30 at 14:52 +0200, Lorenzo Bianconi wrote:
> Allow management frame injection on DFS channels if the channel has been CAC
> checked and is available

> +++ b/net/mac80211/tx.c
> @@ -1694,8 +1694,10 @@ netdev_tx_t ieee80211_monitor_start_xmit(struct sk_buff *skb,
>  	 * radar detection by itself. We can do that later by adding a
>  	 * monitor flag interfaces used for AP support.
>  	 */
> -	if ((chan->flags & (IEEE80211_CHAN_NO_IBSS | IEEE80211_CHAN_RADAR |
> -			    IEEE80211_CHAN_PASSIVE_SCAN)))
> +	if (((chan->flags & (IEEE80211_CHAN_PASSIVE_SCAN |
> +			     IEEE80211_CHAN_NO_IBSS))) ||
> +	    ((chan->flags & IEEE80211_CHAN_RADAR) &&
> +	     chan->dfs_state != NL80211_DFS_AVAILABLE))

This would be the only place where mac80211 is accessing
chan->dfs_state, does that make sense? Why is it not needed elsewhere?

johannes

Re: [PATCH] mac80211: allow mgmt frame transmission on DFS channels

[Lorenzo Bianconi]

Before start beaconing cfg80211_reg_can_beacon() verifies the channel
is CAC checked and available calling cfg80211_secondary_chans_ok().
Although the channel is marked NL80211_DFS_AVAILABLE after a CAC
period, ieee80211_monitor_start_xmit() does not allow to inject mgmt
frames on DFS channels causing association failures.

Lorenzo

2013/10/2 Johannes Berg <johannes@sipsolutions.net>:
> On Mon, 2013-09-30 at 14:52 +0200, Lorenzo Bianconi wrote:
>> Allow management frame injection on DFS channels if the channel has been CAC
>> checked and is available
>
>> +++ b/net/mac80211/tx.c
>> @@ -1694,8 +1694,10 @@ netdev_tx_t ieee80211_monitor_start_xmit(struct sk_buff *skb,
>>        * radar detection by itself. We can do that later by adding a
>>        * monitor flag interfaces used for AP support.
>>        */
>> -     if ((chan->flags & (IEEE80211_CHAN_NO_IBSS | IEEE80211_CHAN_RADAR |
>> -                         IEEE80211_CHAN_PASSIVE_SCAN)))
>> +     if (((chan->flags & (IEEE80211_CHAN_PASSIVE_SCAN |
>> +                          IEEE80211_CHAN_NO_IBSS))) ||
>> +         ((chan->flags & IEEE80211_CHAN_RADAR) &&
>> +          chan->dfs_state != NL80211_DFS_AVAILABLE))
>
> This would be the only place where mac80211 is accessing
> chan->dfs_state, does that make sense? Why is it not needed elsewhere?
>
> johannes
>



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Re: [PATCH] mac80211: allow mgmt frame transmission on DFS channels

[Johannes Berg]

On Wed, 2013-10-02 at 12:07 +0200, Lorenzo Bianconi wrote:
> Before start beaconing cfg80211_reg_can_beacon() verifies the channel
> is CAC checked and available calling cfg80211_secondary_chans_ok().
> Although the channel is marked NL80211_DFS_AVAILABLE after a CAC
> period, ieee80211_monitor_start_xmit() does not allow to inject mgmt
> frames on DFS channels causing association failures.

I don't see how this can cause association failures? Please explain.
DFS-capable hostapd doesn't use monitor interfaces with mac80211 any
more.

johannes

Re: [PATCH] mac80211: allow mgmt frame transmission on DFS channels

[Lorenzo Bianconi]

I am not using latest mac80211/hostapd (in particular
compat-wireless-2013-04-16/hostapd-20130807) because I have to port
some personal stuff. In this scenario I was not able to establish an
AP/STA connection on DFS channel. Anyway I will update these packages.

Lorenzo

2013/10/2 Johannes Berg <johannes@sipsolutions.net>:
> On Wed, 2013-10-02 at 12:07 +0200, Lorenzo Bianconi wrote:
>> Before start beaconing cfg80211_reg_can_beacon() verifies the channel
>> is CAC checked and available calling cfg80211_secondary_chans_ok().
>> Although the channel is marked NL80211_DFS_AVAILABLE after a CAC
>> period, ieee80211_monitor_start_xmit() does not allow to inject mgmt
>> frames on DFS channels causing association failures.
>
> I don't see how this can cause association failures? Please explain.
> DFS-capable hostapd doesn't use monitor interfaces with mac80211 any
> more.
>
> johannes
>



-- 
UNIX is Sexy: who | grep -i blonde | talk; cd ~; wine; talk; touch;
unzip; touch; strip; gasp; finger; gasp; mount; fsck; more; yes; gasp;
umount; make clean; sleep

Re: [PATCH] mac80211: allow mgmt frame transmission on DFS channels

[Johannes Berg]

On Wed, 2013-10-02 at 14:52 +0200, Lorenzo Bianconi wrote:
> I am not using latest mac80211/hostapd (in particular
> compat-wireless-2013-04-16/hostapd-20130807) because I have to port
> some personal stuff. In this scenario I was not able to establish an
> AP/STA connection on DFS channel. Anyway I will update these packages.

But that old hostapd doesn't support DFS to start with, does it? I'm
confused.

johannes

Re: [PATCH] mac80211: allow mgmt frame transmission on DFS channels

[Lorenzo Bianconi]

I am testing some personal hostapd changes in order to add CAC/NOP
management using methods added by Simon

2013/10/2 Johannes Berg <johannes@sipsolutions.net>:
> On Wed, 2013-10-02 at 14:52 +0200, Lorenzo Bianconi wrote:
>> I am not using latest mac80211/hostapd (in particular
>> compat-wireless-2013-04-16/hostapd-20130807) because I have to port
>> some personal stuff. In this scenario I was not able to establish an
>> AP/STA connection on DFS channel. Anyway I will update these packages.
>
> But that old hostapd doesn't support DFS to start with, does it? I'm
> confused.
>
> johannes
>



-- 
UNIX is Sexy: who | grep -i blonde | talk; cd ~; wine; talk; touch;
unzip; touch; strip; gasp; finger; gasp; mount; fsck; more; yes; gasp;
umount; make clean; sleep