Re: [PATCH v2 1/4] cfg80211: leave invalid channels on regdomain change

["Luis R. Rodriguez" <mcgrof@suse.com>]

Johannes, Jouni, please review the comment about WLAN_REASON_DEAUTH_LEAVING
below.

On Thu, Nov 13, 2014 at 06:13:36PM +0200, Arik Nemtsov wrote:
> When the regulatory settings change, some channels might become invalid.
> Disconnect interfaces acting on these channels, after giving userspace
> code a grace period to leave them.
> 
> Signed-off-by: Arik Nemtsov <arikx.nemtsov@intel.com>
> Reviewed-by: Johannes Berg <johannes.berg@intel.com>
> ---
>  include/net/regulatory.h |   6 +++
>  net/wireless/reg.c       | 101 ++++++++++++++++++++++++++++++++++++++++++++++-
>  2 files changed, 106 insertions(+), 1 deletion(-)
> 
> diff --git a/include/net/regulatory.h b/include/net/regulatory.h
> index dad7ab2..701177c 100644
> --- a/include/net/regulatory.h
> +++ b/include/net/regulatory.h
> @@ -136,6 +136,11 @@ struct regulatory_request {
>   *      otherwise initiating radiation is not allowed. This will enable the
>   *      relaxations enabled under the CFG80211_REG_RELAX_NO_IR configuration
>   *      option
> + * @REGULATORY_ENFORCE_CHANNELS: the regulatory core will make sure all
> + *	interfaces on this wiphy reside on allowed channels. Upon a regdomain
> + *	change, the interfaces are given a grace period to disconnect or move
> + *	to an allowed channels. Interfaces on forbidden channels are forcibly
> + *	disconnected.

I don't like this name, it would seem folks not using this don't
get to enforce channels, and that's not right, this is a feature,
and in fact I am not sure why this is being implemented as optional
rather than a standard feature. Care to explain the reasoning there?

> diff --git a/net/wireless/reg.c b/net/wireless/reg.c
> index 7449a8c..6459ddd 100644
> --- a/net/wireless/reg.c
> +++ b/net/wireless/reg.c
> @@ -56,6 +56,7 @@
>  #include <net/cfg80211.h>
>  #include "core.h"
>  #include "reg.h"
> +#include "rdev-ops.h"
>  #include "regdb.h"
>  #include "nl80211.h"
>  
> @@ -66,6 +67,12 @@
>  #define REG_DBG_PRINT(args...)
>  #endif
>  
> +/*
> + * Grace period we give before making sure all current interfaces reside on
> + * channels allowed by the current regulatory domain.
> + */
> +#define REG_ENFORCE_GRACE_MS 60000
> +
>  /**
>   * enum reg_request_treatment - regulatory request treatment
>   *
> @@ -210,6 +217,9 @@ struct reg_beacon {
>  	struct ieee80211_channel chan;
>  };
>  
> +static void reg_check_chans_work(struct work_struct *work);
> +static DECLARE_DELAYED_WORK(reg_check_chans, reg_check_chans_work);
> +
>  static void reg_todo(struct work_struct *work);
>  static DECLARE_WORK(reg_work, reg_todo);
>  
> @@ -1518,6 +1528,90 @@ static void reg_call_notifier(struct wiphy *wiphy,
>  		wiphy->reg_notifier(wiphy, request);
>  }
>  
> +static bool reg_wdev_chan_valid(struct wiphy *wiphy, struct wireless_dev *wdev)
> +{
> +	struct ieee80211_channel *ch;
> +	struct cfg80211_chan_def chandef;
> +	struct cfg80211_registered_device *rdev = wiphy_to_rdev(wiphy);
> +	bool ret = true;
> +
> +	wdev_lock(wdev);
> +
> +	if (!wdev->netdev || !netif_running(wdev->netdev))
> +		goto out;
> +
> +	switch (wdev->iftype) {
> +	case NL80211_IFTYPE_AP:
> +	case NL80211_IFTYPE_P2P_GO:
> +		if (!wdev->beacon_interval)
> +			goto out;
> +
> +		ret = cfg80211_reg_can_beacon(wiphy,
> +					      &wdev->chandef, wdev->iftype);
> +		break;
> +	case NL80211_IFTYPE_STATION:
> +	case NL80211_IFTYPE_P2P_CLIENT:
> +		if (!wdev->current_bss ||
> +		    !wdev->current_bss->pub.channel)
> +			goto out;
> +
> +		ch = wdev->current_bss->pub.channel;
> +		if (rdev->ops->get_channel &&
> +		    !rdev_get_channel(rdev, wdev, &chandef))
> +			ret = cfg80211_chandef_usable(wiphy, &chandef,
> +						      IEEE80211_CHAN_DISABLED);
> +		else
> +			ret = !(ch->flags & IEEE80211_CHAN_DISABLED);
> +		break;
> +	default:
> +		/* others not implemented for now */
> +		pr_info("Regulatory channel check not implemented for mode %d\n",
> +			wdev->iftype);

I feel you are being lazy here, come on, think of it and address it.
It can't be that hard. In fact cfg80211_leave() already deals with
all the logic to leave properly for all types of interfaces, you
just have to come up with the logic to know things should kick
the device off. Its not that hard.

> +		break;
> +	}
> +
> +out:
> +	wdev_unlock(wdev);
> +	return ret;
> +}
> +
> +static void reg_leave_invalid_chans(struct wiphy *wiphy)
> +{
> +	struct wireless_dev *wdev;
> +	struct cfg80211_registered_device *rdev = wiphy_to_rdev(wiphy);
> +
> +	ASSERT_RTNL();
> +
> +	list_for_each_entry(wdev, &rdev->wdev_list, list)
> +		if (!reg_wdev_chan_valid(wiphy, wdev))
> +			cfg80211_leave(rdev, wdev);
> +}

Kind of sad we only have WLAN_REASON_DEAUTH_LEAVING and we
only use this for STAs. You are providing an event for
this trigger so could be understood by the supplicant that
this happened for this reason but I think it'd be a lot
nicer to unify this as part of a disconnect. Johannes,
Jouni, thought?

  Luis