[PATCH] mac80211: improved 802.11g CTS protection

Currently, CTS protection is partially implemented twice:
 1. via prism2 ioctls, only used by hostapd
 2. via STA beacon parsing, recorded in sta.use_protection but never used
    (other than printed in debugfs)

Protection control should be implemented on a per-subif basis. For example,
a single physical device may be running a soft AP on one channel, and a STA
on another. The AP interface should use protection based on what hostapd told
it, and the STA interface should use protection based on beacon parsing.
These should operate independantly: one subif using protection should not
influence the other.

To implement this, I moved the use_protection flag into ieee80211_sub_if_data
and removed the device-global cts_protect_erp_frames flag.

I also made the PRISM2_PARAM_CTS_PROTECT_ERP_FRAMES write operation only
available for AP interfaces, to avoid any possibility of the user messing with
the behaviour of a STA.

Signed-off-by: Daniel Drake <dsd@gentoo.org>
Signed-off-by: Jiri Benc <jbenc@suse.cz>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/mac80211/debugfs_netdev.c

@@ -118,7 +118,7 @@ static ssize_t ieee80211_if_fmt_flags(
 			 sdata->u.sta.authenticated ? "AUTH\n" : "",
 			 sdata->u.sta.associated ? "ASSOC\n" : "",
 			 sdata->u.sta.probereq_poll ? "PROBEREQ POLL\n" : "",
-			 sdata->u.sta.use_protection ? "CTS prot\n" : "");
+			 sdata->use_protection ? "CTS prot\n" : "");
 }
 __IEEE80211_IF_FILE(flags);
 

net/mac80211/ieee80211.c

@@ -442,7 +442,7 @@ ieee80211_tx_h_rate_ctrl(struct ieee80211_txrx_data *tx)
 	if (!tx->u.tx.rate)
 		return TXRX_DROP;
 	if (tx->u.tx.mode->mode == MODE_IEEE80211G &&
-	    tx->local->cts_protect_erp_frames && tx->fragmented &&
+	    tx->sdata->use_protection && tx->fragmented &&
 	    extra.nonerp) {
 		tx->u.tx.last_frag_rate = tx->u.tx.rate;
 		tx->u.tx.probe_last_frag = extra.probe ? 1 : 0;
@@ -868,8 +868,7 @@ ieee80211_tx_h_misc(struct ieee80211_txrx_data *tx)
 	 * for the frame. */
 	if (mode->mode == MODE_IEEE80211G &&
 	    (tx->u.tx.rate->flags & IEEE80211_RATE_ERP) &&
-	    tx->u.tx.unicast &&
+	    tx->u.tx.unicast && tx->sdata->use_protection &&
-	    tx->local->cts_protect_erp_frames &&
 	    !(control->flags & IEEE80211_TXCTL_USE_RTS_CTS))
 		control->flags |= IEEE80211_TXCTL_USE_CTS_PROTECT;
 

net/mac80211/ieee80211_i.h

@@ -241,7 +241,6 @@ struct ieee80211_if_sta {
 	unsigned int authenticated:1;
 	unsigned int associated:1;
 	unsigned int probereq_poll:1;
-	unsigned int use_protection:1;
 	unsigned int create_ibss:1;
 	unsigned int mixed_cell:1;
 	unsigned int wmm_enabled:1;
@@ -284,6 +283,7 @@ struct ieee80211_sub_if_data {
 	int mc_count;
 	unsigned int allmulti:1;
 	unsigned int promisc:1;
+	unsigned int use_protection:1; /* CTS protect ERP frames */
 
 	struct net_device_stats stats;
 	int drop_unencrypted;
@@ -444,7 +444,6 @@ struct ieee80211_local {
 	int *basic_rates[NUM_IEEE80211_MODES];
 
 	int rts_threshold;
-	int cts_protect_erp_frames;
 	int fragmentation_threshold;
 	int short_retry_limit; /* dot11ShortRetryLimit */
 	int long_retry_limit; /* dot11LongRetryLimit */

net/mac80211/ieee80211_ioctl.c

@@ -1180,7 +1180,10 @@ static int ieee80211_ioctl_prism2_param(struct net_device *dev,
 		break;
 
 	case PRISM2_PARAM_CTS_PROTECT_ERP_FRAMES:
-		local->cts_protect_erp_frames = value;
+		if (sdata->type != IEEE80211_IF_TYPE_AP)
+			ret = -ENOENT;
+		else
+			sdata->use_protection = value;
 		break;
 
 	case PRISM2_PARAM_PREAMBLE:
@@ -1303,7 +1306,7 @@ static int ieee80211_ioctl_get_prism2_param(struct net_device *dev,
 		break;
 
 	case PRISM2_PARAM_CTS_PROTECT_ERP_FRAMES:
-		*param = local->cts_protect_erp_frames;
+		*param = sdata->use_protection;
 		break;
 
 	case PRISM2_PARAM_PREAMBLE:

net/mac80211/ieee80211_sta.c

@@ -316,12 +316,11 @@ static void ieee80211_sta_wmm_params(struct net_device *dev,
 
 static void ieee80211_handle_erp_ie(struct net_device *dev, u8 erp_value)
 {
-	struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
 	struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
 	struct ieee80211_if_sta *ifsta = &sdata->u.sta;
 	int use_protection = (erp_value & WLAN_ERP_USE_PROTECTION) != 0;
 
-	if (use_protection != !!ifsta->use_protection) {
+	if (use_protection != sdata->use_protection) {
 		if (net_ratelimit()) {
 			printk(KERN_DEBUG "%s: CTS protection %s (BSSID="
 			       MAC_FMT ")\n",
@@ -329,8 +328,7 @@ static void ieee80211_handle_erp_ie(struct net_device *dev, u8 erp_value)
 			       use_protection ? "enabled" : "disabled",
 			       MAC_ARG(ifsta->bssid));
 		}
-		ifsta->use_protection = use_protection ? 1 : 0;
+		sdata->use_protection = use_protection;
-		local->cts_protect_erp_frames = use_protection;
 	}
 }
 
@@ -390,6 +388,7 @@ static void ieee80211_set_associated(struct net_device *dev,
 				     struct ieee80211_if_sta *ifsta, int assoc)
 {
 	union iwreq_data wrqu;
+	struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
 
 	if (ifsta->associated == assoc)
 		return;
@@ -417,6 +416,7 @@ static void ieee80211_set_associated(struct net_device *dev,
 		ieee80211_sta_send_associnfo(dev, ifsta);
 	} else {
 		netif_carrier_off(dev);
+		sdata->use_protection = 0;
 		memset(wrqu.ap_addr.sa_data, 0, ETH_ALEN);
 	}
 	wrqu.ap_addr.sa_family = ARPHRD_ETHER;