airo: switch to skcipher interface

The AIRO driver applies a ctr(aes) on a buffer of considerable size
(2400 bytes), and instead of invoking the crypto API to handle this
in its entirety, it open codes the counter manipulation and invokes
the AES block cipher directly.

Let's fix this, by switching to the sync skcipher API instead.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/cisco/Kconfig

@@ -17,6 +17,7 @@ config AIRO
 	depends on CFG80211 && ISA_DMA_API && (PCI || BROKEN)
 	select WIRELESS_EXT
 	select CRYPTO
+	select CRYPTO_BLKCIPHER
 	select WEXT_SPY
 	select WEXT_PRIV
 	---help---
@@ -40,6 +41,7 @@ config AIRO_CS
 	select WEXT_PRIV
 	select CRYPTO
 	select CRYPTO_AES
+	select CRYPTO_CTR
 	---help---
 	  This is the standard Linux driver to support Cisco/Aironet PCMCIA
 	  802.11 wireless cards.  This driver is the same as the Aironet

drivers/net/wireless/cisco/airo.c

@@ -49,6 +49,9 @@
 #include <linux/kthread.h>
 #include <linux/freezer.h>
 
+#include <crypto/aes.h>
+#include <crypto/skcipher.h>
+
 #include <net/cfg80211.h>
 #include <net/iw_handler.h>
 
@@ -951,7 +954,7 @@ typedef struct {
 } mic_statistics;
 
 typedef struct {
-	u32 coeff[((EMMH32_MSGLEN_MAX)+3)>>2];
+	__be32 coeff[((EMMH32_MSGLEN_MAX)+3)>>2];
 	u64 accum;	// accumulated mic, reduced to u32 in final()
 	int position;	// current position (byte offset) in message
 	union {
@@ -1216,7 +1219,7 @@ struct airo_info {
 	struct iw_spy_data	spy_data;
 	struct iw_public_data	wireless_data;
 	/* MIC stuff */
-	struct crypto_cipher	*tfm;
+	struct crypto_sync_skcipher	*tfm;
 	mic_module		mod[2];
 	mic_statistics		micstats;
 	HostRxDesc rxfids[MPI_MAX_FIDS]; // rx/tx/config MPI350 descriptors
@@ -1291,14 +1294,14 @@ static int flashrestart(struct airo_info *ai,struct net_device *dev);
 static int RxSeqValid (struct airo_info *ai,miccntx *context,int mcast,u32 micSeq);
 static void MoveWindow(miccntx *context, u32 micSeq);
 static void emmh32_setseed(emmh32_context *context, u8 *pkey, int keylen,
-			   struct crypto_cipher *tfm);
+			   struct crypto_sync_skcipher *tfm);
 static void emmh32_init(emmh32_context *context);
 static void emmh32_update(emmh32_context *context, u8 *pOctets, int len);
 static void emmh32_final(emmh32_context *context, u8 digest[4]);
 static int flashpchar(struct airo_info *ai,int byte,int dwelltime);
 
 static void age_mic_context(miccntx *cur, miccntx *old, u8 *key, int key_len,
-			    struct crypto_cipher *tfm)
+			    struct crypto_sync_skcipher *tfm)
 {
 	/* If the current MIC context is valid and its key is the same as
 	 * the MIC register, there's nothing to do.
@@ -1359,7 +1362,7 @@ static int micsetup(struct airo_info *ai) {
 	int i;
 
 	if (ai->tfm == NULL)
-		ai->tfm = crypto_alloc_cipher("aes", 0, 0);
+		ai->tfm = crypto_alloc_sync_skcipher("ctr(aes)", 0, 0);
 
         if (IS_ERR(ai->tfm)) {
                 airo_print_err(ai->dev->name, "failed to load transform for AES");
@@ -1624,37 +1627,31 @@ static void MoveWindow(miccntx *context, u32 micSeq)
 
 /* mic accumulate */
 #define MIC_ACCUM(val)	\
-	context->accum += (u64)(val) * context->coeff[coeff_position++];
-
-static unsigned char aes_counter[16];
+	context->accum += (u64)(val) * be32_to_cpu(context->coeff[coeff_position++]);
 
 /* expand the key to fill the MMH coefficient array */
 static void emmh32_setseed(emmh32_context *context, u8 *pkey, int keylen,
-			   struct crypto_cipher *tfm)
+			   struct crypto_sync_skcipher *tfm)
 {
   /* take the keying material, expand if necessary, truncate at 16-bytes */
   /* run through AES counter mode to generate context->coeff[] */
   
-	int i,j;
-	u32 counter;
-	u8 *cipher, plain[16];
+	SYNC_SKCIPHER_REQUEST_ON_STACK(req, tfm);
+	struct scatterlist sg;
+	u8 iv[AES_BLOCK_SIZE] = {};
+	int ret;
 
-	crypto_cipher_setkey(tfm, pkey, 16);
-	counter = 0;
-	for (i = 0; i < ARRAY_SIZE(context->coeff); ) {
-		aes_counter[15] = (u8)(counter >> 0);
-		aes_counter[14] = (u8)(counter >> 8);
-		aes_counter[13] = (u8)(counter >> 16);
-		aes_counter[12] = (u8)(counter >> 24);
-		counter++;
-		memcpy (plain, aes_counter, 16);
-		crypto_cipher_encrypt_one(tfm, plain, plain);
-		cipher = plain;
-		for (j = 0; (j < 16) && (i < ARRAY_SIZE(context->coeff)); ) {
-			context->coeff[i++] = ntohl(*(__be32 *)&cipher[j]);
-			j += 4;
-		}
-	}
+	crypto_sync_skcipher_setkey(tfm, pkey, 16);
+
+	memset(context->coeff, 0, sizeof(context->coeff));
+	sg_init_one(&sg, context->coeff, sizeof(context->coeff));
+
+	skcipher_request_set_sync_tfm(req, tfm);
+	skcipher_request_set_callback(req, 0, NULL, NULL);
+	skcipher_request_set_crypt(req, &sg, &sg, sizeof(context->coeff), iv);
+
+	ret = crypto_skcipher_encrypt(req);
+	WARN_ON_ONCE(ret);
 }
 
 /* prepare for calculation of a new mic */
@@ -2415,7 +2412,7 @@ void stop_airo_card( struct net_device *dev, int freeres )
 				ai->shared, ai->shared_dma);
 		}
         }
-	crypto_free_cipher(ai->tfm);
+	crypto_free_sync_skcipher(ai->tfm);
 	del_airo_dev(ai);
 	free_netdev( dev );
 }