cfg80211: support bigger kek/kck key length

With some newer AKMs, the KCK and KEK are bigger, so allow that
if the driver advertises support for it. In addition, add a new
attribute for the AKM so we can use it for offloaded rekeying.

Signed-off-by: Nathan Errera <nathan.errera@intel.com>
[reword commit message]
Link: https://lore.kernel.org/r/20200528212237.5eb58b00a5d1.I61b09d77c4f382e8d58a05dcca78096e99a6bc15@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

include/net/cfg80211.h

@@ -2936,12 +2936,17 @@ struct cfg80211_wowlan_wakeup {
 
 /**
  * struct cfg80211_gtk_rekey_data - rekey data
- * @kek: key encryption key (NL80211_KEK_LEN bytes)
- * @kck: key confirmation key (NL80211_KCK_LEN bytes)
+ * @kek: key encryption key (@kek_len bytes)
+ * @kck: key confirmation key (@kck_len bytes)
  * @replay_ctr: replay counter (NL80211_REPLAY_CTR_LEN bytes)
+ * @kek_len: length of kek
+ * @kck_len length of kck
+ * @akm: akm (oui, id)
  */
 struct cfg80211_gtk_rekey_data {
 	const u8 *kek, *kck, *replay_ctr;
+	u32 akm;
+	u8 kek_len, kck_len;
 };
 
 /**
@@ -4166,9 +4171,10 @@ struct cfg80211_ops {
  *	beaconing mode (AP, IBSS, Mesh, ...).
  * @WIPHY_FLAG_HAS_STATIC_WEP: The device supports static WEP key installation
  *	before connection.
+ * @WIPHY_FLAG_SUPPORTS_EXT_KEK_KCK: The device supports bigger kek and kck keys
  */
 enum wiphy_flags {
-	/* use hole at 0 */
+	WIPHY_FLAG_SUPPORTS_EXT_KEK_KCK		= BIT(0),
 	/* use hole at 1 */
 	/* use hole at 2 */
 	WIPHY_FLAG_NETNS_OK			= BIT(3),

include/uapi/linux/nl80211.h

@@ -5396,6 +5396,8 @@ enum plink_actions {
 
 #define NL80211_KCK_LEN			16
 #define NL80211_KEK_LEN			16
+#define NL80211_KCK_EXT_LEN		24
+#define NL80211_KEK_EXT_LEN		32
 #define NL80211_REPLAY_CTR_LEN		8
 
 /**
@@ -5404,6 +5406,7 @@ enum plink_actions {
  * @NL80211_REKEY_DATA_KEK: key encryption key (binary)
  * @NL80211_REKEY_DATA_KCK: key confirmation key (binary)
  * @NL80211_REKEY_DATA_REPLAY_CTR: replay counter (binary)
+ * @NL80211_REKEY_DATA_AKM: AKM data (OUI, suite type)
  * @NUM_NL80211_REKEY_DATA: number of rekey attributes (internal)
  * @MAX_NL80211_REKEY_DATA: highest rekey attribute (internal)
  */
@@ -5412,6 +5415,7 @@ enum nl80211_rekey_data {
 	NL80211_REKEY_DATA_KEK,
 	NL80211_REKEY_DATA_KCK,
 	NL80211_REKEY_DATA_REPLAY_CTR,
+	NL80211_REKEY_DATA_AKM,
 
 	/* keep last */
 	NUM_NL80211_REKEY_DATA,

net/wireless/nl80211.c

@@ -730,9 +730,16 @@ nl80211_coalesce_policy[NUM_NL80211_ATTR_COALESCE_RULE] = {
 /* policy for GTK rekey offload attributes */
 static const struct nla_policy
 nl80211_rekey_policy[NUM_NL80211_REKEY_DATA] = {
-	[NL80211_REKEY_DATA_KEK] = NLA_POLICY_EXACT_LEN_WARN(NL80211_KEK_LEN),
-	[NL80211_REKEY_DATA_KCK] = NLA_POLICY_EXACT_LEN_WARN(NL80211_KCK_LEN),
+	[NL80211_REKEY_DATA_KEK] = {
+		.type = NLA_BINARY,
+		.len = NL80211_KEK_EXT_LEN
+	},
+	[NL80211_REKEY_DATA_KCK] = {
+		.type = NLA_BINARY,
+		.len = NL80211_KCK_EXT_LEN
+	},
 	[NL80211_REKEY_DATA_REPLAY_CTR] = NLA_POLICY_EXACT_LEN_WARN(NL80211_REPLAY_CTR_LEN),
+	[NL80211_REKEY_DATA_AKM] = { .type = NLA_U32 },
 };
 
 static const struct nla_policy
@@ -12347,14 +12354,22 @@ static int nl80211_set_rekey_data(struct sk_buff *skb, struct genl_info *info)
 		return -EINVAL;
 	if (nla_len(tb[NL80211_REKEY_DATA_REPLAY_CTR]) != NL80211_REPLAY_CTR_LEN)
 		return -ERANGE;
-	if (nla_len(tb[NL80211_REKEY_DATA_KEK]) != NL80211_KEK_LEN)
+	if (nla_len(tb[NL80211_REKEY_DATA_KEK]) != NL80211_KEK_LEN &&
+	    !(rdev->wiphy.flags & WIPHY_FLAG_SUPPORTS_EXT_KEK_KCK &&
+	      nla_len(tb[NL80211_REKEY_DATA_KEK]) == NL80211_KEK_EXT_LEN))
 		return -ERANGE;
-	if (nla_len(tb[NL80211_REKEY_DATA_KCK]) != NL80211_KCK_LEN)
+	if (nla_len(tb[NL80211_REKEY_DATA_KCK]) != NL80211_KCK_LEN &&
+	    !(rdev->wiphy.flags & WIPHY_FLAG_SUPPORTS_EXT_KEK_KCK &&
+	      nla_len(tb[NL80211_REKEY_DATA_KEK]) == NL80211_KCK_EXT_LEN))
 		return -ERANGE;
 
 	rekey_data.kek = nla_data(tb[NL80211_REKEY_DATA_KEK]);
 	rekey_data.kck = nla_data(tb[NL80211_REKEY_DATA_KCK]);
 	rekey_data.replay_ctr = nla_data(tb[NL80211_REKEY_DATA_REPLAY_CTR]);
+	rekey_data.kek_len = nla_len(tb[NL80211_REKEY_DATA_KEK]);
+	rekey_data.kck_len = nla_len(tb[NL80211_REKEY_DATA_KCK]);
+	if (tb[NL80211_REKEY_DATA_AKM])
+		rekey_data.akm = nla_get_u32(tb[NL80211_REKEY_DATA_AKM]);
 
 	wdev_lock(wdev);
 	if (!wdev->current_bss) {