bluetooth: switch to AES library

The bluetooth code uses a bare AES cipher for the encryption operations.
Given that it carries out a set_key() operation right before every
encryption operation, this is clearly not a hot path, and so the use of
the cipher interface (which provides the best implementation available
on the system) is not really required.

In fact, when using a cipher like AES-NI or AES-CE, both the set_key()
and the encrypt() operations involve en/disabling preemption as well as
stacking and unstacking the SIMD context, and this is most certainly
not worth it for encrypting 16 bytes of data.

So let's switch to the new lightweight library interface instead.

Signed-off-by: Ard Biesheuvel <[e-mail]>
Signed-off-by: Herbert Xu <[e-mail]>

net/bluetooth/Kconfig

···
 	select CRC16
 	select CRYPTO
 	select CRYPTO_BLKCIPHER
-	select CRYPTO_AES
+	select CRYPTO_LIB_AES
+	imply CRYPTO_AES
 	select CRYPTO_CMAC
 	select CRYPTO_ECB
 	select CRYPTO_SHA256

net/bluetooth/smp.c

···
 #include <linux/debugfs.h>
 #include <linux/scatterlist.h>
 #include <linux/crypto.h>
+#include <crypto/aes.h>
 #include <crypto/algapi.h>
 #include <crypto/b128ops.h>
 #include <crypto/hash.h>
···
 	u8			local_rand[16];
 	bool			debug_key;
 
-	struct crypto_cipher	*tfm_aes;
 	struct crypto_shash	*tfm_cmac;
 	struct crypto_kpp	*tfm_ecdh;
 };
···
 	u8			dhkey[32];
 	u8			mackey[16];
 
-	struct crypto_cipher	*tfm_aes;
 	struct crypto_shash	*tfm_cmac;
 	struct crypto_kpp	*tfm_ecdh;
 };
···
  * s1 and ah.
  */
 
-static int smp_e(struct crypto_cipher *tfm, const u8 *k, u8 *r)
+static int smp_e(const u8 *k, u8 *r)
 {
+	struct crypto_aes_ctx ctx;
 	uint8_t tmp[16], data[16];
 	int err;
 
 	SMP_DBG("k %16phN r %16phN", k, r);
 
-	if (!tfm) {
-		BT_ERR("tfm %p", tfm);
-		return -EINVAL;
-	}
-
 	/* The most significant octet of key corresponds to k[0] */
 	swap_buf(k, tmp, 16);
 
-	err = crypto_cipher_setkey(tfm, tmp, 16);
+	err = aes_expandkey(&ctx, tmp, 16);
 	if (err) {
 		BT_ERR("cipher setkey failed: %d", err);
 		return err;
···
 	/* Most significant octet of plaintextData corresponds to data[0] */
 	swap_buf(r, data, 16);
 
-	crypto_cipher_encrypt_one(tfm, data, data);
+	aes_encrypt(&ctx, data, data);
 
 	/* Most significant octet of encryptedData corresponds to data[0] */
 	swap_buf(data, r, 16);
 
 	SMP_DBG("r %16phN", r);
 
+	memzero_explicit(&ctx, sizeof (ctx));
 	return err;
 }
 
-static int smp_c1(struct crypto_cipher *tfm_aes, const u8 k[16],
+static int smp_c1(const u8 k[16],
 		  const u8 r[16], const u8 preq[7], const u8 pres[7], u8 _iat,
 		  const bdaddr_t *ia, u8 _rat, const bdaddr_t *ra, u8 res[16])
 {
···
 	u128_xor((u128 *) res, (u128 *) r, (u128 *) p1);
 
 	/* res = e(k, res) */
-	err = smp_e(tfm_aes, k, res);
+	err = smp_e(k, res);
 	if (err) {
 		BT_ERR("Encrypt data error");
 		return err;
···
 	u128_xor((u128 *) res, (u128 *) res, (u128 *) p2);
 
 	/* res = e(k, res) */
-	err = smp_e(tfm_aes, k, res);
+	err = smp_e(k, res);
 	if (err)
 		BT_ERR("Encrypt data error");
 
 	return err;
 }
 
-static int smp_s1(struct crypto_cipher *tfm_aes, const u8 k[16],
+static int smp_s1(const u8 k[16],
 		  const u8 r1[16], const u8 r2[16], u8 _r[16])
 {
 	int err;
···
 	memcpy(_r, r2, 8);
 	memcpy(_r + 8, r1, 8);
 
-	err = smp_e(tfm_aes, k, _r);
+	err = smp_e(k, _r);
 	if (err)
 		BT_ERR("Encrypt data error");
 
 	return err;
 }
 
-static int smp_ah(struct crypto_cipher *tfm, const u8 irk[16],
-		  const u8 r[3], u8 res[3])
+static int smp_ah(const u8 irk[16], const u8 r[3], u8 res[3])
 {
 	u8 _res[16];
 	int err;
···
 	memcpy(_res, r, 3);
 	memset(_res + 3, 0, 13);
 
-	err = smp_e(tfm, irk, _res);
+	err = smp_e(irk, _res);
 	if (err) {
 		BT_ERR("Encrypt error");
 		return err;
···
 
 	BT_DBG("RPA %pMR IRK %*phN", bdaddr, 16, irk);
 
-	err = smp_ah(smp->tfm_aes, irk, &bdaddr->b[3], hash);
+	err = smp_ah(irk, &bdaddr->b[3], hash);
 	if (err)
 		return false;
 
···
 	rpa->b[5] &= 0x3f;	/* Clear two most significant bits */
 	rpa->b[5] |= 0x40;	/* Set second most significant bit */
 
-	err = smp_ah(smp->tfm_aes, irk, &rpa->b[3], rpa->b);
+	err = smp_ah(irk, &rpa->b[3], rpa->b);
 	if (err < 0)
 		return err;
 
···
 	kzfree(smp->slave_csrk);
 	kzfree(smp->link_key);
 
-	crypto_free_cipher(smp->tfm_aes);
 	crypto_free_shash(smp->tfm_cmac);
 	crypto_free_kpp(smp->tfm_ecdh);
 
···
 
 	BT_DBG("conn %p", conn);
 
-	ret = smp_c1(smp->tfm_aes, smp->tk, smp->prnd, smp->preq, smp->prsp,
+	ret = smp_c1(smp->tk, smp->prnd, smp->preq, smp->prsp,
 		     conn->hcon->init_addr_type, &conn->hcon->init_addr,
 		     conn->hcon->resp_addr_type, &conn->hcon->resp_addr,
 		     cp.confirm_val);
···
 	u8 confirm[16];
 	int ret;
 
-	if (IS_ERR_OR_NULL(smp->tfm_aes))
-		return SMP_UNSPECIFIED;
-
 	BT_DBG("conn %p %s", conn, conn->hcon->out ? "master" : "slave");
 
-	ret = smp_c1(smp->tfm_aes, smp->tk, smp->rrnd, smp->preq, smp->prsp,
+	ret = smp_c1(smp->tk, smp->rrnd, smp->preq, smp->prsp,
 		     hcon->init_addr_type, &hcon->init_addr,
 		     hcon->resp_addr_type, &hcon->resp_addr, confirm);
 	if (ret)
···
 		__le64 rand = 0;
 		__le16 ediv = 0;
 
-		smp_s1(smp->tfm_aes, smp->tk, smp->rrnd, smp->prnd, stk);
+		smp_s1(smp->tk, smp->rrnd, smp->prnd, stk);
 
 		if (test_and_set_bit(HCI_CONN_ENCRYPT_PEND, &hcon->flags))
 			return SMP_UNSPECIFIED;
···
 		smp_send_cmd(conn, SMP_CMD_PAIRING_RANDOM, sizeof(smp->prnd),
 			     smp->prnd);
 
-		smp_s1(smp->tfm_aes, smp->tk, smp->prnd, smp->rrnd, stk);
+		smp_s1(smp->tk, smp->prnd, smp->rrnd, stk);
 
 		if (hcon->pending_sec_level == BT_SECURITY_HIGH)
 			auth = 1;
···
 	if (!smp)
 		return NULL;
 
-	smp->tfm_aes = crypto_alloc_cipher("aes", 0, 0);
-	if (IS_ERR(smp->tfm_aes)) {
-		BT_ERR("Unable to create AES crypto context");
-		goto zfree_smp;
-	}
-
 	smp->tfm_cmac = crypto_alloc_shash("cmac(aes)", 0, 0);
 	if (IS_ERR(smp->tfm_cmac)) {
 		BT_ERR("Unable to create CMAC crypto context");
-		goto free_cipher;
+		goto zfree_smp;
 	}
 
 	smp->tfm_ecdh = crypto_alloc_kpp("ecdh", CRYPTO_ALG_INTERNAL, 0);
···
 
 free_shash:
 	crypto_free_shash(smp->tfm_cmac);
-free_cipher:
-	crypto_free_cipher(smp->tfm_aes);
 zfree_smp:
 	kzfree(smp);
 	return NULL;
···
 {
 	struct l2cap_chan *chan;
 	struct smp_dev *smp;
-	struct crypto_cipher *tfm_aes;
 	struct crypto_shash *tfm_cmac;
 	struct crypto_kpp *tfm_ecdh;
 
···
 	if (!smp)
 		return ERR_PTR(-ENOMEM);
 
-	tfm_aes = crypto_alloc_cipher("aes", 0, 0);
-	if (IS_ERR(tfm_aes)) {
-		BT_ERR("Unable to create AES crypto context");
-		kzfree(smp);
-		return ERR_CAST(tfm_aes);
-	}
-
 	tfm_cmac = crypto_alloc_shash("cmac(aes)", 0, 0);
 	if (IS_ERR(tfm_cmac)) {
 		BT_ERR("Unable to create CMAC crypto context");
-		crypto_free_cipher(tfm_aes);
 		kzfree(smp);
 		return ERR_CAST(tfm_cmac);
 	}
···
 	if (IS_ERR(tfm_ecdh)) {
 		BT_ERR("Unable to create ECDH crypto context");
 		crypto_free_shash(tfm_cmac);
-		crypto_free_cipher(tfm_aes);
 		kzfree(smp);
 		return ERR_CAST(tfm_ecdh);
 	}
 
 	smp->local_oob = false;
-	smp->tfm_aes = tfm_aes;
 	smp->tfm_cmac = tfm_cmac;
 	smp->tfm_ecdh = tfm_ecdh;
 
···
 	chan = l2cap_chan_create();
 	if (!chan) {
 		if (smp) {
-			crypto_free_cipher(smp->tfm_aes);
 			crypto_free_shash(smp->tfm_cmac);
 			crypto_free_kpp(smp->tfm_ecdh);
 			kzfree(smp);
···
 	smp = chan->data;
 	if (smp) {
 		chan->data = NULL;
-		crypto_free_cipher(smp->tfm_aes);
 		crypto_free_shash(smp->tfm_cmac);
 		crypto_free_kpp(smp->tfm_ecdh);
 		kzfree(smp);
···
 	return 0;
 }
 
-static int __init test_ah(struct crypto_cipher *tfm_aes)
+static int __init test_ah(void)
 {
 	const u8 irk[16] = {
 			0x9b, 0x7d, 0x39, 0x0a, 0xa6, 0x10, 0x10, 0x34,
···
 	u8 res[3];
 	int err;
 
-	err = smp_ah(tfm_aes, irk, r, res);
+	err = smp_ah(irk, r, res);
 	if (err)
 		return err;
 
···
 	return 0;
 }
 
-static int __init test_c1(struct crypto_cipher *tfm_aes)
+static int __init test_c1(void)
 {
 	const u8 k[16] = {
 			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
···
 	u8 res[16];
 	int err;
 
-	err = smp_c1(tfm_aes, k, r, preq, pres, _iat, &ia, _rat, &ra, res);
+	err = smp_c1(k, r, preq, pres, _iat, &ia, _rat, &ra, res);
 	if (err)
 		return err;
 
···
 	return 0;
 }
 
-static int __init test_s1(struct crypto_cipher *tfm_aes)
+static int __init test_s1(void)
 {
 	const u8 k[16] = {
 			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
···
 	u8 res[16];
 	int err;
 
-	err = smp_s1(tfm_aes, k, r1, r2, res);
+	err = smp_s1(k, r1, r2, res);
 	if (err)
 		return err;
 
···
 	.llseek		= default_llseek,
 };
 
-static int __init run_selftests(struct crypto_cipher *tfm_aes,
-				struct crypto_shash *tfm_cmac,
+static int __init run_selftests(struct crypto_shash *tfm_cmac,
 				struct crypto_kpp *tfm_ecdh)
 {
 	ktime_t calltime, delta, rettime;
···
 		goto done;
 	}
 
-	err = test_ah(tfm_aes);
+	err = test_ah();
 	if (err) {
 		BT_ERR("smp_ah test failed");
 		goto done;
 	}
 
-	err = test_c1(tfm_aes);
+	err = test_c1();
 	if (err) {
 		BT_ERR("smp_c1 test failed");
 		goto done;
 	}
 
-	err = test_s1(tfm_aes);
+	err = test_s1();
 	if (err) {
 		BT_ERR("smp_s1 test failed");
 		goto done;
···
 
 int __init bt_selftest_smp(void)
 {
-	struct crypto_cipher *tfm_aes;
 	struct crypto_shash *tfm_cmac;
 	struct crypto_kpp *tfm_ecdh;
 	int err;
 
-	tfm_aes = crypto_alloc_cipher("aes", 0, 0);
-	if (IS_ERR(tfm_aes)) {
-		BT_ERR("Unable to create AES crypto context");
-		return PTR_ERR(tfm_aes);
-	}
-
 	tfm_cmac = crypto_alloc_shash("cmac(aes)", 0, 0);
 	if (IS_ERR(tfm_cmac)) {
 		BT_ERR("Unable to create CMAC crypto context");
-		crypto_free_cipher(tfm_aes);
 		return PTR_ERR(tfm_cmac);
 	}
 
···
 	if (IS_ERR(tfm_ecdh)) {
 		BT_ERR("Unable to create ECDH crypto context");
 		crypto_free_shash(tfm_cmac);
-		crypto_free_cipher(tfm_aes);
 		return PTR_ERR(tfm_ecdh);
 	}
 
-	err = run_selftests(tfm_aes, tfm_cmac, tfm_ecdh);
+	err = run_selftests(tfm_cmac, tfm_ecdh);
 
 	crypto_free_shash(tfm_cmac);
-	crypto_free_cipher(tfm_aes);
 	crypto_free_kpp(tfm_ecdh);
 
 	return err;