[PATCH 1/4] cfg80211: mesh: track (and thus validate) beacon interval

[PATCH 1/4] cfg80211: mesh: track (and thus validate) beacon interval

[Johannes Berg]

From: Johannes Berg <johannes.berg@intel.com>

This is needed for beacon interval validation; if we don't
store it, then new interfaces added won't validate that the
beacon interval is the same as existing ones. Fix this.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
---
 net/wireless/mesh.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/wireless/mesh.c b/net/wireless/mesh.c
index fa2066b56f36..2d8518a37eab 100644
--- a/net/wireless/mesh.c
+++ b/net/wireless/mesh.c
@@ -183,6 +183,7 @@ int __cfg80211_join_mesh(struct cfg80211_registered_device *rdev,
 		memcpy(wdev->ssid, setup->mesh_id, setup->mesh_id_len);
 		wdev->mesh_id_len = setup->mesh_id_len;
 		wdev->chandef = setup->chandef;
+		wdev->beacon_interval = setup->beacon_interval;
 	}
 
 	return err;
@@ -258,6 +259,7 @@ int __cfg80211_leave_mesh(struct cfg80211_registered_device *rdev,
 	err = rdev_leave_mesh(rdev, dev);
 	if (!err) {
 		wdev->mesh_id_len = 0;
+		wdev->beacon_interval = 0;
 		memset(&wdev->chandef, 0, sizeof(wdev->chandef));
 		rdev_set_qos_map(rdev, dev, NULL);
 	}
-- 
2.8.1

[PATCH 2/4] cfg80211: disallow beacon_int_min_gcd with IBSS

[Johannes Berg]

From: Johannes Berg <johannes.berg@intel.com>

This can't really be supported right now, because the IBSS
interface may change its beacon interval at any time due to
joining another network; thus, there's already "support"
for different beacon intervals here, implicitly.

Until we figure out how we should handle this case (continue
to allow it to arbitrarily join? Join only if compatible?)
disallow advertising that different beacon intervals are
supported if IBSS is allowed.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
---
 net/wireless/core.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/net/wireless/core.c b/net/wireless/core.c
index 725adff6c7d4..158c59ecf90a 100644
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -562,6 +562,21 @@ static int wiphy_verify_combinations(struct wiphy *wiphy)
 				    c->limits[j].max > 1))
 				return -EINVAL;
 
+			/*
+			 * This isn't well-defined right now. If you have an
+			 * IBSS interface, then its beacon interval may change
+			 * by joining other networks, and nothing prevents it
+			 * from doing that.
+			 * So technically we probably shouldn't even allow AP
+			 * and IBSS in the same interface, but it seems that
+			 * some drivers support that, possibly only with fixed
+			 * beacon intervals for IBSS.
+			 */
+			if (WARN_ON(types & BIT(NL80211_IFTYPE_ADHOC) &&
+				    c->beacon_int_min_gcd)) {
+				return -EINVAL;
+			}
+
 			cnt += c->limits[j].max;
 			/*
 			 * Don't advertise an unsupported type
-- 
2.8.1

[PATCH 3/4] cfg80211: validate beacon int as part of iface combinations

[Johannes Berg]

From: Johannes Berg <johannes.berg@intel.com>

Remove the pointless checking against interface combinations in
the initial basic beacon interval validation, that currently isn't
taking into account radar detection or channels properly. Instead,
just validate the basic range there, and then delay real checking
to the interface combination validation that drivers must do.

This means that drivers wanting to use the beacon_int_min_gcd will
now have to pass the new_beacon_int when validating the AP/mesh
start.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
---
 include/net/cfg80211.h | 12 +++-----
 net/wireless/util.c    | 82 +++++++++++++++++++++++++++++++-------------------
 2 files changed, 55 insertions(+), 39 deletions(-)

diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index ec39f891b7a3..d1ffbc3a8e55 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -784,19 +784,15 @@ struct cfg80211_csa_settings {
  * @iftype_num: array with the number of interfaces of each interface
  *	type.  The index is the interface type as specified in &enum
  *	nl80211_iftype.
- * @beacon_int_gcd: a value specifying GCD of all beaconing interfaces,
- *	the GCD of a single value is considered the value itself, so for
- *	a single interface this should be set to that interface's beacon
- *	interval
- * @beacon_int_different: a flag indicating whether or not all beacon
- *	intervals (of beaconing interfaces) are different or not.
+ * @new_beacon_int: set this to the beacon interval of a new interface
+ *	that's not operating yet, if such is to be checked as part of
+ *	the verification
  */
 struct iface_combination_params {
 	int num_different_channels;
 	u8 radar_detect;
 	int iftype_num[NUM_NL80211_IFTYPES];
-	u32 beacon_int_gcd;
-	bool beacon_int_different;
+	u32 new_beacon_int;
 };
 
 /**
diff --git a/net/wireless/util.c b/net/wireless/util.c
index 78bf53705466..40d7a6bf9432 100644
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -13,6 +13,7 @@
 #include <net/dsfield.h>
 #include <linux/if_vlan.h>
 #include <linux/mpls.h>
+#include <linux/gcd.h>
 #include "core.h"
 #include "rdev-ops.h"
 
@@ -1558,47 +1559,52 @@ bool ieee80211_chandef_to_operating_class(struct cfg80211_chan_def *chandef,
 }
 EXPORT_SYMBOL(ieee80211_chandef_to_operating_class);
 
-int cfg80211_validate_beacon_int(struct cfg80211_registered_device *rdev,
-				 enum nl80211_iftype iftype, u32 beacon_int)
+static void cfg80211_calculate_bi_data(struct wiphy *wiphy, u32 new_beacon_int,
+				       u32 *beacon_int_gcd,
+				       bool *beacon_int_different)
 {
 	struct wireless_dev *wdev;
-	struct iface_combination_params params = {
-		.beacon_int_gcd = beacon_int,	/* GCD(n) = n */
-	};
 
-	if (beacon_int < 10 || beacon_int > 10000)
-		return -EINVAL;
+	*beacon_int_gcd = 0;
+	*beacon_int_different = false;
 
-	params.iftype_num[iftype] = 1;
-	list_for_each_entry(wdev, &rdev->wiphy.wdev_list, list) {
+	list_for_each_entry(wdev, &wiphy->wdev_list, list) {
 		if (!wdev->beacon_interval)
 			continue;
 
-		params.iftype_num[wdev->iftype]++;
-	}
-
-	list_for_each_entry(wdev, &rdev->wiphy.wdev_list, list) {
-		u32 bi_prev = wdev->beacon_interval;
-
-		if (!wdev->beacon_interval)
+		if (!*beacon_int_gcd) {
+			*beacon_int_gcd = wdev->beacon_interval;
 			continue;
+		}
 
-		/* slight optimisation - skip identical BIs */
-		if (wdev->beacon_interval == beacon_int)
+		if (wdev->beacon_interval == *beacon_int_gcd)
 			continue;
 
-		params.beacon_int_different = true;
-
-		/* Get the GCD */
-		while (bi_prev != 0) {
-			u32 tmp_bi = bi_prev;
+		*beacon_int_different = true;
+		*beacon_int_gcd = gcd(*beacon_int_gcd, wdev->beacon_interval);
+	}
 
-			bi_prev = params.beacon_int_gcd % bi_prev;
-			params.beacon_int_gcd = tmp_bi;
-		}
+	if (new_beacon_int && *beacon_int_gcd != new_beacon_int) {
+		*beacon_int_different = true;
+		*beacon_int_gcd = gcd(*beacon_int_gcd, new_beacon_int);
 	}
+}
 
-	return cfg80211_check_combinations(&rdev->wiphy, &params);
+int cfg80211_validate_beacon_int(struct cfg80211_registered_device *rdev,
+				 enum nl80211_iftype iftype, u32 beacon_int)
+{
+	/*
+	 * This is just a basic pre-condition check; if interface combinations
+	 * are possible the driver must already be checking those with a call
+	 * to cfg80211_check_combinations(), in which case we'll validate more
+	 * through the cfg80211_calculate_bi_data() call and code in
+	 * cfg80211_iter_combinations().
+	 */
+
+	if (beacon_int < 10 || beacon_int > 10000)
+		return -EINVAL;
+
+	return 0;
 }
 
 int cfg80211_iter_combinations(struct wiphy *wiphy,
@@ -1612,6 +1618,21 @@ int cfg80211_iter_combinations(struct wiphy *wiphy,
 	int i, j, iftype;
 	int num_interfaces = 0;
 	u32 used_iftypes = 0;
+	u32 beacon_int_gcd;
+	bool beacon_int_different;
+
+	/*
+	 * This is a bit strange, since the iteration used to rely only on
+	 * the data given by the driver, but here it now relies on context,
+	 * in form of the currently operating interfaces.
+	 * This is OK for all current users, and saves us from having to
+	 * push the GCD calculations into all the drivers.
+	 * In the future, this should probably rely more on data that's in
+	 * cfg80211 already - the only thing not would appear to be any new
+	 * interfaces (while being brought up) and channel/radar data.
+	 */
+	cfg80211_calculate_bi_data(wiphy, params->new_beacon_int,
+				   &beacon_int_gcd, &beacon_int_different);
 
 	if (params->radar_detect) {
 		rcu_read_lock();
@@ -1674,12 +1695,11 @@ int cfg80211_iter_combinations(struct wiphy *wiphy,
 		if ((all_iftypes & used_iftypes) != used_iftypes)
 			goto cont;
 
-		if (params->beacon_int_gcd) {
+		if (beacon_int_gcd) {
 			if (c->beacon_int_min_gcd &&
-			    params->beacon_int_gcd < c->beacon_int_min_gcd)
+			    beacon_int_gcd < c->beacon_int_min_gcd)
 				goto cont;
-			if (!c->beacon_int_min_gcd &&
-			    params->beacon_int_different)
+			if (!c->beacon_int_min_gcd && beacon_int_different)
 				goto cont;
 		}
 
-- 
2.8.1

[PATCH 4/4] mac80211: validate new interface's beacon intervals

[Johannes Berg]

From: Johannes Berg <johannes.berg@intel.com>

As part of interface combination checking, verify any new
interface's beacon intervals. In fact, just always add the
beacon interval since that's harmless.

With this patch, mac80211 is prepared for drivers that set
the min_beacon_int_gcd parameter in interface combinations.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
---
 net/mac80211/cfg.c  |  3 ++-
 net/mac80211/util.c | 10 ++++++++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index eb68add4393c..e91e503bf992 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -864,6 +864,8 @@ static int ieee80211_start_ap(struct wiphy *wiphy, struct net_device *dev,
 	}
 	sdata->needed_rx_chains = sdata->local->rx_chains;
 
+	sdata->vif.bss_conf.beacon_int = params->beacon_interval;
+
 	mutex_lock(&local->mtx);
 	err = ieee80211_vif_use_channel(sdata, &params->chandef,
 					IEEE80211_CHANCTX_SHARED);
@@ -894,7 +896,6 @@ static int ieee80211_start_ap(struct wiphy *wiphy, struct net_device *dev,
 					      vlan->vif.type);
 	}
 
-	sdata->vif.bss_conf.beacon_int = params->beacon_interval;
 	sdata->vif.bss_conf.dtim_period = params->dtim_period;
 	sdata->vif.bss_conf.enable_beacon = true;
 	sdata->vif.bss_conf.allow_p2p_go_ps = sdata->vif.p2p;
diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index 7f24bdc68f71..ac59fbd280df 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -3326,6 +3326,16 @@ int ieee80211_check_combinations(struct ieee80211_sub_if_data *sdata,
 	if (WARN_ON(iftype >= NUM_NL80211_IFTYPES))
 		return -EINVAL;
 
+	if (sdata->vif.type == NL80211_IFTYPE_AP ||
+	    sdata->vif.type == NL80211_IFTYPE_MESH_POINT) {
+		/*
+		 * always passing this is harmless, since it'll be the
+		 * same value that cfg80211 finds if it finds the same
+		 * interface ... and that's always allowed
+		 */
+		params.new_beacon_int = sdata->vif.bss_conf.beacon_int;
+	}
+
 	/* Always allow software iftypes */
 	if (local->hw.wiphy->software_iftypes & BIT(iftype)) {
 		if (radar_detect)
-- 
2.8.1