[PATCH v3 4/5] wifi: mac80211: refactor CMAC crypt functions

[Chien Wong <m@xv97.com>]

ieee80211_aes_cmac() and ieee80211_aes_cmac_256() are almost the same.
Merge them. This removes duplication.

It should be noted that the refactored ieee80211_aes_cmac() permits
8 bytes output for CMAC-256 and 16 bytes output for CMAC-128. In such
cases, it would generate result correctly as expected.

All references to the refactored functions in the tree are adapted.

Signed-off-by: Chien Wong <m@xv97.com>
---
 net/mac80211/aes_cmac.c | 53 ++++++++++-------------------------------
 net/mac80211/aes_cmac.h |  4 +---
 net/mac80211/wpa.c      | 16 ++++++++-----
 3 files changed, 24 insertions(+), 49 deletions(-)

diff --git a/net/mac80211/aes_cmac.c b/net/mac80211/aes_cmac.c
index 01fb8b6c5dfb..588e3c9879b3 100644
--- a/net/mac80211/aes_cmac.c
+++ b/net/mac80211/aes_cmac.c
@@ -16,20 +16,21 @@
 #include "key.h"
 #include "aes_cmac.h"
 
-#define CMAC_TLEN IEEE80211_CMAC_128_MIC_LEN
-#define CMAC_TLEN_256 IEEE80211_CMAC_256_MIC_LEN
 #define AAD_LEN 20
 
-static const u8 zero[CMAC_TLEN_256];
+static const u8 zero[IEEE80211_CMAC_256_MIC_LEN];
 
 int ieee80211_aes_cmac(struct crypto_shash *tfm, const u8 *aad,
-		       const u8 *data, size_t data_len, u8 *mic)
+		       const u8 *data, size_t data_len, u8 *mic, unsigned int mic_len)
 {
 	int err;
 	SHASH_DESC_ON_STACK(desc, tfm);
-	u8 out[AES_BLOCK_SIZE];
 	const __le16 *fc;
 
+	if (mic_len != IEEE80211_CMAC_128_MIC_LEN &&
+	    mic_len != IEEE80211_CMAC_256_MIC_LEN)
+		return -EINVAL;
+
 	desc->tfm = tfm;
 
 	err = crypto_shash_init(desc);
@@ -44,53 +45,25 @@ int ieee80211_aes_cmac(struct crypto_shash *tfm, const u8 *aad,
 		err = crypto_shash_update(desc, zero, 8);
 		if (err)
 			goto out;
-		err = crypto_shash_update(desc, data + 8, data_len - 8 - CMAC_TLEN);
+		err = crypto_shash_update(desc, data + 8, data_len - 8 - mic_len);
 		if (err)
 			goto out;
 	} else {
-		err = crypto_shash_update(desc, data, data_len - CMAC_TLEN);
+		err = crypto_shash_update(desc, data, data_len - mic_len);
 		if (err)
 			goto out;
 	}
-	err = crypto_shash_finup(desc, zero, CMAC_TLEN, out);
-	if (err)
-		goto out;
-	memcpy(mic, out, CMAC_TLEN);
-out:
-	return err;
-}
 
-int ieee80211_aes_cmac_256(struct crypto_shash *tfm, const u8 *aad,
-			   const u8 *data, size_t data_len, u8 *mic)
-{
-	int err;
-	SHASH_DESC_ON_STACK(desc, tfm);
-	const __le16 *fc;
+	if (mic_len == IEEE80211_CMAC_128_MIC_LEN) {
+		u8 out[AES_BLOCK_SIZE];
 
-	desc->tfm = tfm;
-
-	err = crypto_shash_init(desc);
-	if (err)
-		goto out;
-	err = crypto_shash_update(desc, aad, AAD_LEN);
-	if (err)
-		goto out;
-	fc = (const __le16 *)aad;
-	if (ieee80211_is_beacon(*fc)) {
-		/* mask Timestamp field to zero */
-		err = crypto_shash_update(desc, zero, 8);
-		if (err)
-			goto out;
-		err = crypto_shash_update(desc, data + 8,
-					  data_len - 8 - CMAC_TLEN_256);
+		err = crypto_shash_finup(desc, zero, mic_len, out);
 		if (err)
 			goto out;
+		memcpy(mic, out, mic_len);
 	} else {
-		err = crypto_shash_update(desc, data, data_len - CMAC_TLEN_256);
-		if (err)
-			goto out;
+		err = crypto_shash_finup(desc, zero, mic_len, mic);
 	}
-	err = crypto_shash_finup(desc, zero, CMAC_TLEN_256, mic);
 out:
 	return err;
 }
diff --git a/net/mac80211/aes_cmac.h b/net/mac80211/aes_cmac.h
index f74150542142..631fc3033576 100644
--- a/net/mac80211/aes_cmac.h
+++ b/net/mac80211/aes_cmac.h
@@ -12,9 +12,7 @@
 struct crypto_shash *ieee80211_aes_cmac_key_setup(const u8 key[],
 						  size_t key_len);
 int ieee80211_aes_cmac(struct crypto_shash *tfm, const u8 *aad,
-		       const u8 *data, size_t data_len, u8 *mic);
-int ieee80211_aes_cmac_256(struct crypto_shash *tfm, const u8 *aad,
-			   const u8 *data, size_t data_len, u8 *mic);
+		       const u8 *data, size_t data_len, u8 *mic, unsigned int mic_len);
 void ieee80211_aes_cmac_key_free(struct crypto_shash *tfm);
 
 #endif /* AES_CMAC_H */
diff --git a/net/mac80211/wpa.c b/net/mac80211/wpa.c
index bb0fa505cdca..2c1ee4b8e205 100644
--- a/net/mac80211/wpa.c
+++ b/net/mac80211/wpa.c
@@ -870,7 +870,8 @@ ieee80211_crypto_aes_cmac_encrypt(struct ieee80211_tx_data *tx)
 	 * MIC = AES-128-CMAC(IGTK, AAD || Management Frame Body || MMIE, 64)
 	 */
 	if (ieee80211_aes_cmac(key->u.aes_cmac.tfm, aad,
-			       skb->data + 24, skb->len - 24, mmie->mic))
+			       skb->data + 24, skb->len - 24, mmie->mic,
+			       IEEE80211_CMAC_128_MIC_LEN))
 		return TX_DROP;
 
 	return TX_CONTINUE;
@@ -917,8 +918,9 @@ ieee80211_crypto_aes_cmac_256_encrypt(struct ieee80211_tx_data *tx)
 
 	/* MIC = AES-256-CMAC(IGTK, AAD || Management Frame Body || MMIE, 128)
 	 */
-	if (ieee80211_aes_cmac_256(key->u.aes_cmac.tfm, aad,
-				   skb->data + 24, skb->len - 24, mmie->mic))
+	if (ieee80211_aes_cmac(key->u.aes_cmac.tfm, aad,
+			       skb->data + 24, skb->len - 24, mmie->mic,
+			       IEEE80211_CMAC_256_MIC_LEN))
 		return TX_DROP;
 
 	return TX_CONTINUE;
@@ -959,7 +961,8 @@ ieee80211_crypto_aes_cmac_decrypt(struct ieee80211_rx_data *rx)
 		/* hardware didn't decrypt/verify MIC */
 		bip_aad(skb, aad);
 		if (ieee80211_aes_cmac(key->u.aes_cmac.tfm, aad,
-				       skb->data + 24, skb->len - 24, mic))
+				       skb->data + 24, skb->len - 24, mic,
+				       IEEE80211_CMAC_128_MIC_LEN))
 			return RX_DROP_U_DECRYPT_FAIL;
 		if (crypto_memneq(mic, mmie->mic, sizeof(mmie->mic))) {
 			key->u.aes_cmac.icverrors++;
@@ -1009,8 +1012,9 @@ ieee80211_crypto_aes_cmac_256_decrypt(struct ieee80211_rx_data *rx)
 	if (!(status->flag & RX_FLAG_DECRYPTED)) {
 		/* hardware didn't decrypt/verify MIC */
 		bip_aad(skb, aad);
-		if (ieee80211_aes_cmac_256(key->u.aes_cmac.tfm, aad,
-					   skb->data + 24, skb->len - 24, mic))
+		if (ieee80211_aes_cmac(key->u.aes_cmac.tfm, aad,
+				       skb->data + 24, skb->len - 24, mic,
+				       IEEE80211_CMAC_256_MIC_LEN))
 			return RX_DROP_U_DECRYPT_FAIL;
 		if (crypto_memneq(mic, mmie->mic, sizeof(mmie->mic))) {
 			key->u.aes_cmac.icverrors++;
-- 
2.51.2