mac80211: expose AES-CMAC subkey calculation

Expose a function for the AES-CMAC subkey calculation
to drivers. This is the first step of the AES-CMAC
cipher key setup and may be required for CMAC hardware
offloading.

Signed-off-by: Assaf Krauss <assaf.krauss@intel.com>
Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

include/net/mac80211.h

@@ -3222,6 +3222,19 @@ void ieee80211_get_tkip_rx_p1k(struct ieee80211_key_conf *keyconf,
 void ieee80211_get_tkip_p2k(struct ieee80211_key_conf *keyconf,
 			    struct sk_buff *skb, u8 *p2k);
 
+/**
+ * ieee80211_aes_cmac_calculate_k1_k2 - calculate the AES-CMAC sub keys
+ *
+ * This function computes the two AES-CMAC sub-keys, based on the
+ * previously installed master key.
+ *
+ * @keyconf: the parameter passed with the set key
+ * @k1: a buffer to be filled with the 1st sub-key
+ * @k2: a buffer to be filled with the 2nd sub-key
+ */
+void ieee80211_aes_cmac_calculate_k1_k2(struct ieee80211_key_conf *keyconf,
+					u8 *k1, u8 *k2);
+
 /**
  * struct ieee80211_key_seq - key sequence counter
  *

net/mac80211/aes_cmac.c

@@ -126,3 +126,20 @@ void ieee80211_aes_cmac_key_free(struct crypto_cipher *tfm)
 {
 	crypto_free_cipher(tfm);
 }
+
+void ieee80211_aes_cmac_calculate_k1_k2(struct ieee80211_key_conf *keyconf,
+					u8 *k1, u8 *k2)
+{
+	u8 l[AES_BLOCK_SIZE] = {};
+	struct ieee80211_key *key =
+		container_of(keyconf, struct ieee80211_key, conf);
+
+	crypto_cipher_encrypt_one(key->u.aes_cmac.tfm, l, l);
+
+	memcpy(k1, l, AES_BLOCK_SIZE);
+	gf_mulx(k1);
+
+	memcpy(k2, k1, AES_BLOCK_SIZE);
+	gf_mulx(k2);
+}
+EXPORT_SYMBOL(ieee80211_aes_cmac_calculate_k1_k2);