cfg80211: Support key configuration for Beacon protection (BIGTK)

IEEE P802.11-REVmd/D3.0 adds support for protecting Beacon frames using
a new set of keys (BIGTK; key index 6..7) similarly to the way
group-addressed Robust Management frames are protected (IGTK; key index
4..5). Extend cfg80211 and nl80211 to allow the new BIGTK to be
configured. Add an extended feature flag to indicate driver support for
the new key index values to avoid array overflows in driver
implementations and also to indicate to user space when this
functionality is available.

Signed-off-by: Jouni Malinen <jouni@codeaurora.org>
Link: https://lore.kernel.org/r/20200222132548.20835-2-jouni@codeaurora.org
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

7 files changed, 101 insertions, 14 deletions

diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index 682ee4d..04b6df1 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -3369,6 +3369,8 @@ struct cfg80211_update_owe_info {
  * @set_default_key: set the default key on an interface
  *
  * @set_default_mgmt_key: set the default management frame key on an interface
+
+ * @set_default_beacon_key: set the default Beacon frame key on an interface
  *
  * @set_rekey_data: give the data necessary for GTK rekeying to the driver
  *
@@ -3702,6 +3704,9 @@ struct cfg80211_ops {
 	int	(*set_default_mgmt_key)(struct wiphy *wiphy,
 					struct net_device *netdev,
 					u8 key_index);
+	int	(*set_default_beacon_key)(struct wiphy *wiphy,
+					  struct net_device *netdev,
+					  u8 key_index);
 
 	int	(*start_ap)(struct wiphy *wiphy, struct net_device *dev,
 			    struct cfg80211_ap_settings *settings);
diff --git a/include/uapi/linux/nl80211.h b/include/uapi/linux/nl80211.h
index 350ab86..934e62f 100644
--- a/include/uapi/linux/nl80211.h
+++ b/include/uapi/linux/nl80211.h
@@ -4550,6 +4550,7 @@ enum nl80211_key_default_types {
  *	See &enum nl80211_key_default_types.
  * @NL80211_KEY_MODE: the mode from enum nl80211_key_mode.
  *	Defaults to @NL80211_KEY_RX_TX.
+ * @NL80211_KEY_DEFAULT_BEACON: flag indicating default Beacon frame key
  *
  * @__NL80211_KEY_AFTER_LAST: internal
  * @NL80211_KEY_MAX: highest key attribute
@@ -4565,6 +4566,7 @@ enum nl80211_key_attributes {
 	NL80211_KEY_TYPE,
 	NL80211_KEY_DEFAULT_TYPES,
 	NL80211_KEY_MODE,
+	NL80211_KEY_DEFAULT_BEACON,
 
 	/* keep last */
 	__NL80211_KEY_AFTER_LAST,
@@ -5539,6 +5541,9 @@ enum nl80211_feature_flags {
  *	feature, which prevents bufferbloat by using the expected transmission
  *	time to limit the amount of data buffered in the hardware.
  *
+ * @NL80211_EXT_FEATURE_BEACON_PROTECTION: The driver supports Beacon protection
+ *	and can receive key configuration for BIGTK using key indexes 6 and 7.
+ *
  * @NUM_NL80211_EXT_FEATURES: number of extended features.
  * @MAX_NL80211_EXT_FEATURES: highest extended feature index.
  */
@@ -5586,6 +5591,7 @@ enum nl80211_ext_feature_index {
 	NL80211_EXT_FEATURE_SAE_OFFLOAD,
 	NL80211_EXT_FEATURE_VLAN_OFFLOAD,
 	NL80211_EXT_FEATURE_AQL,
+	NL80211_EXT_FEATURE_BEACON_PROTECTION,
 
 	/* add new features before the definition below */
 	NUM_NL80211_EXT_FEATURES,
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index ce55a2c..a75f722 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -368,7 +368,7 @@ const struct nla_policy nl80211_policy[NUM_NL80211_ATTR] = {
 	[NL80211_ATTR_KEY] = { .type = NLA_NESTED, },
 	[NL80211_ATTR_KEY_DATA] = { .type = NLA_BINARY,
 				    .len = WLAN_MAX_KEY_LEN },
-	[NL80211_ATTR_KEY_IDX] = NLA_POLICY_MAX(NLA_U8, 5),
+	[NL80211_ATTR_KEY_IDX] = NLA_POLICY_MAX(NLA_U8, 7),
 	[NL80211_ATTR_KEY_CIPHER] = { .type = NLA_U32 },
 	[NL80211_ATTR_KEY_DEFAULT] = { .type = NLA_FLAG },
 	[NL80211_ATTR_KEY_SEQ] = { .type = NLA_BINARY, .len = 16 },
@@ -1037,7 +1037,7 @@ struct key_parse {
 	struct key_params p;
 	int idx;
 	int type;
-	bool def, defmgmt;
+	bool def, defmgmt, defbeacon;
 	bool def_uni, def_multi;
 };
 
@@ -1053,12 +1053,13 @@ static int nl80211_parse_key_new(struct genl_info *info, struct nlattr *key,
 
 	k->def = !!tb[NL80211_KEY_DEFAULT];
 	k->defmgmt = !!tb[NL80211_KEY_DEFAULT_MGMT];
+	k->defbeacon = !!tb[NL80211_KEY_DEFAULT_BEACON];
 
 	if (k->def) {
 		k->def_uni = true;
 		k->def_multi = true;
 	}
-	if (k->defmgmt)
+	if (k->defmgmt || k->defbeacon)
 		k->def_multi = true;
 
 	if (tb[NL80211_KEY_IDX])
@@ -1165,14 +1166,17 @@ static int nl80211_parse_key(struct genl_info *info, struct key_parse *k)
 	if (err)
 		return err;
 
-	if (k->def && k->defmgmt) {
-		GENL_SET_ERR_MSG(info, "key with def && defmgmt is invalid");
+	if ((k->def ? 1 : 0) + (k->defmgmt ? 1 : 0) +
+	    (k->defbeacon ? 1 : 0) > 1) {
+		GENL_SET_ERR_MSG(info,
+				 "key with multiple default flags is invalid");
 		return -EINVAL;
 	}
 
-	if (k->defmgmt) {
+	if (k->defmgmt || k->defbeacon) {
 		if (k->def_uni || !k->def_multi) {
-			GENL_SET_ERR_MSG(info, "defmgmt key must be mcast");
+			GENL_SET_ERR_MSG(info,
+					 "defmgmt/defbeacon key must be mcast");
 			return -EINVAL;
 		}
 	}
@@ -1184,14 +1188,20 @@ static int nl80211_parse_key(struct genl_info *info, struct key_parse *k)
 						 "defmgmt key idx not 4 or 5");
 				return -EINVAL;
 			}
+		} else if (k->defbeacon) {
+			if (k->idx < 6 || k->idx > 7) {
+				GENL_SET_ERR_MSG(info,
+						 "defbeacon key idx not 6 or 7");
+				return -EINVAL;
+			}
 		} else if (k->def) {
 			if (k->idx < 0 || k->idx > 3) {
 				GENL_SET_ERR_MSG(info, "def key idx not 0-3");
 				return -EINVAL;
 			}
 		} else {
-			if (k->idx < 0 || k->idx > 5) {
-				GENL_SET_ERR_MSG(info, "key idx not 0-5");
+			if (k->idx < 0 || k->idx > 7) {
+				GENL_SET_ERR_MSG(info, "key idx not 0-7");
 				return -EINVAL;
 			}
 		}
@@ -3817,8 +3827,14 @@ static int nl80211_get_key(struct sk_buff *skb, struct genl_info *info)
 	void *hdr;
 	struct sk_buff *msg;
 
-	if (info->attrs[NL80211_ATTR_KEY_IDX])
+	if (info->attrs[NL80211_ATTR_KEY_IDX]) {
 		key_idx = nla_get_u8(info->attrs[NL80211_ATTR_KEY_IDX]);
+		if (key_idx > 5 &&
+		    !wiphy_ext_feature_isset(
+			    &rdev->wiphy,
+			    NL80211_EXT_FEATURE_BEACON_PROTECTION))
+			return -EINVAL;
+	}
 
 	if (info->attrs[NL80211_ATTR_MAC])
 		mac_addr = nla_data(info->attrs[NL80211_ATTR_MAC]);
@@ -3894,7 +3910,7 @@ static int nl80211_set_key(struct sk_buff *skb, struct genl_info *info)
 	/* Only support setting default key and
 	 * Extended Key ID action NL80211_KEY_SET_TX.
 	 */
-	if (!key.def && !key.defmgmt &&
+	if (!key.def && !key.defmgmt && !key.defbeacon &&
 	    !(key.p.mode == NL80211_KEY_SET_TX))
 		return -EINVAL;
 
@@ -3941,6 +3957,24 @@ static int nl80211_set_key(struct sk_buff *skb, struct genl_info *info)
 #ifdef CONFIG_CFG80211_WEXT
 		dev->ieee80211_ptr->wext.default_mgmt_key = key.idx;
 #endif
+	} else if (key.defbeacon) {
+		if (key.def_uni || !key.def_multi) {
+			err = -EINVAL;
+			goto out;
+		}
+
+		if (!rdev->ops->set_default_beacon_key) {
+			err = -EOPNOTSUPP;
+			goto out;
+		}
+
+		err = nl80211_key_allowed(dev->ieee80211_ptr);
+		if (err)
+			goto out;
+
+		err = rdev_set_default_beacon_key(rdev, dev, key.idx);
+		if (err)
+			goto out;
 	} else if (key.p.mode == NL80211_KEY_SET_TX &&
 		   wiphy_ext_feature_isset(&rdev->wiphy,
 					   NL80211_EXT_FEATURE_EXT_KEY_ID)) {
diff --git a/net/wireless/rdev-ops.h b/net/wireless/rdev-ops.h
index e0d34f7..af7fcf2 100644
--- a/net/wireless/rdev-ops.h
+++ b/net/wireless/rdev-ops.h
@@ -136,6 +136,19 @@ rdev_set_default_mgmt_key(struct cfg80211_registered_device *rdev,
 	return ret;
 }
 
+static inline int
+rdev_set_default_beacon_key(struct cfg80211_registered_device *rdev,
+			    struct net_device *netdev, u8 key_index)
+{
+	int ret;
+
+	trace_rdev_set_default_beacon_key(&rdev->wiphy, netdev, key_index);
+	ret = rdev->ops->set_default_beacon_key(&rdev->wiphy, netdev,
+						key_index);
+	trace_rdev_return_int(&rdev->wiphy, ret);
+	return ret;
+}
+
 static inline int rdev_start_ap(struct cfg80211_registered_device *rdev,
 				struct net_device *dev,
 				struct cfg80211_ap_settings *settings)
diff --git a/net/wireless/sme.c b/net/wireless/sme.c
index d32a2ec..ac3e60a 100644
--- a/net/wireless/sme.c
+++ b/net/wireless/sme.c
@@ -1111,9 +1111,16 @@ void __cfg80211_disconnected(struct net_device *dev, const u8 *ie,
 	 * Delete all the keys ... pairwise keys can't really
 	 * exist any more anyway, but default keys might.
 	 */
-	if (rdev->ops->del_key)
-		for (i = 0; i < 6; i++)
+	if (rdev->ops->del_key) {
+		int max_key_idx = 5;
+
+		if (wiphy_ext_feature_isset(
+			    wdev->wiphy,
+			    NL80211_EXT_FEATURE_BEACON_PROTECTION))
+			max_key_idx = 7;
+		for (i = 0; i <= max_key_idx; i++)
 			rdev_del_key(rdev, dev, i, false, NULL);
+	}
 
 	rdev_set_qos_map(rdev, dev, NULL);
 
diff --git a/net/wireless/trace.h b/net/wireless/trace.h
index 3ef1679..56b7822 100644
--- a/net/wireless/trace.h
+++ b/net/wireless/trace.h
@@ -510,6 +510,23 @@ TRACE_EVENT(rdev_set_default_mgmt_key,
 		  WIPHY_PR_ARG, NETDEV_PR_ARG, __entry->key_index)
 );
 
+TRACE_EVENT(rdev_set_default_beacon_key,
+	TP_PROTO(struct wiphy *wiphy, struct net_device *netdev, u8 key_index),
+	TP_ARGS(wiphy, netdev, key_index),
+	TP_STRUCT__entry(
+		WIPHY_ENTRY
+		NETDEV_ENTRY
+		__field(u8, key_index)
+	),
+	TP_fast_assign(
+		WIPHY_ASSIGN;
+		NETDEV_ASSIGN;
+		__entry->key_index = key_index;
+	),
+	TP_printk(WIPHY_PR_FMT ", " NETDEV_PR_FMT ", key index: %u",
+		  WIPHY_PR_ARG, NETDEV_PR_ARG, __entry->key_index)
+);
+
 TRACE_EVENT(rdev_start_ap,
 	TP_PROTO(struct wiphy *wiphy, struct net_device *netdev,
 		 struct cfg80211_ap_settings *settings),
diff --git a/net/wireless/util.c b/net/wireless/util.c
index 8481e9a..72926f8 100644
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -231,7 +231,12 @@ int cfg80211_validate_key_settings(struct cfg80211_registered_device *rdev,
 				   struct key_params *params, int key_idx,
 				   bool pairwise, const u8 *mac_addr)
 {
-	if (key_idx < 0 || key_idx > 5)
+	int max_key_idx = 5;
+
+	if (wiphy_ext_feature_isset(&rdev->wiphy,
+				    NL80211_EXT_FEATURE_BEACON_PROTECTION))
+		max_key_idx = 7;
+	if (key_idx < 0 || key_idx > max_key_idx)
 		return -EINVAL;
 
 	if (!pairwise && mac_addr && !(rdev->wiphy.flags & WIPHY_FLAG_IBSS_RSN))