Bluetooth: convert smp and selftest to crypto kpp API

* Convert both smp and selftest to crypto kpp API
* Remove module ecc as no more required
* Add ecdh_helper functions for wrapping kpp async calls

This patch has been tested *only* with selftest, which is called on
module loading.
Signed-off-by: Salvatore Benedetto <salvatore.benedetto@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

net/bluetooth/Kconfig

@@ -13,6 +13,7 @@ menuconfig BT
 	select CRYPTO_CMAC
 	select CRYPTO_ECB
 	select CRYPTO_SHA256
+	select CRYPTO_ECDH
 	help
 	  Bluetooth is low-cost, low-power, short-range wireless technology.
 	  It was designed as a replacement for cables and other short-range

net/bluetooth/Makefile

@@ -13,7 +13,7 @@ bluetooth_6lowpan-y := 6lowpan.o
 
 bluetooth-y := af_bluetooth.o hci_core.o hci_conn.o hci_event.o mgmt.o \
 	hci_sock.o hci_sysfs.o l2cap_core.o l2cap_sock.o smp.o lib.o \
-	ecc.o hci_request.o mgmt_util.o
+	ecdh_helper.o hci_request.o mgmt_util.o
 
 bluetooth-$(CONFIG_BT_BREDR) += sco.o
 bluetooth-$(CONFIG_BT_HS) += a2mp.o amp.o

net/bluetooth/ecc.h

-/*
- * Copyright (c) 2013, Kenneth MacKay
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *  * Redistributions of source code must retain the above copyright
- *   notice, this list of conditions and the following disclaimer.
- *  * Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-/* Create a public/private key pair.
- * Outputs:
- *	public_key  - Will be filled in with the public key.
- *	private_key - Will be filled in with the private key.
- *
- * Returns true if the key pair was generated successfully, false
- * if an error occurred. The keys are with the LSB first.
- */
-bool ecc_make_key(u8 public_key[64], u8 private_key[32]);
-
-/* Compute a shared secret given your secret key and someone else's
- * public key.
- * Note: It is recommended that you hash the result of ecdh_shared_secret
- * before using it for symmetric encryption or HMAC.
- *
- * Inputs:
- *	public_key  - The public key of the remote party
- *	private_key - Your private key.
- *
- * Outputs:
- *	secret - Will be filled in with the shared secret value.
- *
- * Returns true if the shared secret was generated successfully, false
- * if an error occurred. Both input and output parameters are with the
- * LSB first.
- */
-bool ecdh_shared_secret(const u8 public_key[64], const u8 private_key[32],
-		        u8 secret[32]);

net/bluetooth/ecdh_helper.c

+/*
+ * ECDH helper functions - KPP wrappings
+ *
+ * Copyright (C) 2017 Intel Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation;
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT OF THIRD PARTY RIGHTS.
+ * IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) AND AUTHOR(S) BE LIABLE FOR ANY
+ * CLAIM, OR ANY SPECIAL INDIRECT OR CONSEQUENTIAL DAMAGES, OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ * ALL LIABILITY, INCLUDING LIABILITY FOR INFRINGEMENT OF ANY PATENTS,
+ * COPYRIGHTS, TRADEMARKS OR OTHER RIGHTS, RELATING TO USE OF THIS
+ * SOFTWARE IS DISCLAIMED.
+ */
+#include "ecdh_helper.h"
+
+#include <linux/random.h>
+#include <linux/scatterlist.h>
+#include <crypto/kpp.h>
+#include <crypto/ecdh.h>
+
+struct ecdh_completion {
+	struct completion completion;
+	int err;
+};
+
+static void ecdh_complete(struct crypto_async_request *req, int err)
+{
+	struct ecdh_completion *res = req->data;
+
+	if (err == -EINPROGRESS)
+		return;
+
+	res->err = err;
+	complete(&res->completion);
+}
+
+static inline void swap_digits(u64 *in, u64 *out, unsigned int ndigits)
+{
+	int i;
+
+	for (i = 0; i < ndigits; i++)
+		out[i] = __swab64(in[ndigits - 1 - i]);
+}
+
+bool compute_ecdh_secret(const u8 public_key[64], const u8 private_key[32],
+			 u8 secret[32])
+{
+	struct crypto_kpp *tfm;
+	struct kpp_request *req;
+	struct ecdh p;
+	struct ecdh_completion result;
+	struct scatterlist src, dst;
+	u8 tmp[64];
+	u8 *buf;
+	unsigned int buf_len;
+	int err = -ENOMEM;
+
+	tfm = crypto_alloc_kpp("ecdh", CRYPTO_ALG_INTERNAL, 0);
+	if (IS_ERR(tfm)) {
+		pr_err("alg: kpp: Failed to load tfm for kpp: %ld\n",
+		       PTR_ERR(tfm));
+		return false;
+	}
+
+	req = kpp_request_alloc(tfm, GFP_KERNEL);
+	if (!req)
+		goto free_kpp;
+
+	init_completion(&result.completion);
+
+	/* Security Manager Protocol holds digits in litte-endian order
+	 * while ECC API expect big-endian data
+	 */
+	swap_digits((u64 *)private_key, (u64 *)tmp, 4);
+	p.key = (char *)tmp;
+	p.key_size = 32;
+	/* Set curve_id */
+	p.curve_id = ECC_CURVE_NIST_P256;
+	buf_len = crypto_ecdh_key_len(&p);
+	buf = kmalloc(buf_len, GFP_KERNEL);
+	if (!buf) {
+		pr_err("alg: kpp: Failed to allocate %d bytes for buf\n",
+		       buf_len);
+		goto free_req;
+	}
+	crypto_ecdh_encode_key(buf, buf_len, &p);
+
+	/* Set A private Key */
+	err = crypto_kpp_set_secret(tfm, (void *)buf, buf_len);
+	if (err)
+		goto free_all;
+
+	swap_digits((u64 *)public_key, (u64 *)tmp, 4); /* x */
+	swap_digits((u64 *)&public_key[32], (u64 *)&tmp[32], 4); /* y */
+
+	sg_init_one(&src, tmp, 64);
+	sg_init_one(&dst, secret, 32);
+	kpp_request_set_input(req, &src, 64);
+	kpp_request_set_output(req, &dst, 32);
+	kpp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
+				 ecdh_complete, &result);
+	err = crypto_kpp_compute_shared_secret(req);
+	if (err == -EINPROGRESS) {
+		wait_for_completion(&result.completion);
+		err = result.err;
+	}
+	if (err < 0) {
+		pr_err("alg: ecdh: compute shared secret failed. err %d\n",
+		       err);
+		goto free_all;
+	}
+
+	swap_digits((u64 *)secret, (u64 *)tmp, 4);
+	memcpy(secret, tmp, 32);
+
+free_all:
+	kzfree(buf);
+free_req:
+	kpp_request_free(req);
+free_kpp:
+	crypto_free_kpp(tfm);
+	return (err == 0);
+}
+
+bool generate_ecdh_keys(u8 public_key[64], u8 private_key[32])
+{
+	struct crypto_kpp *tfm;
+	struct kpp_request *req;
+	struct ecdh p;
+	struct ecdh_completion result;
+	struct scatterlist dst;
+	u8 tmp[64];
+	u8 *buf;
+	unsigned int buf_len;
+	int err = -ENOMEM;
+	const unsigned short max_tries = 16;
+	unsigned short tries = 0;
+
+	tfm = crypto_alloc_kpp("ecdh", CRYPTO_ALG_INTERNAL, 0);
+	if (IS_ERR(tfm)) {
+		pr_err("alg: kpp: Failed to load tfm for kpp: %ld\n",
+		       PTR_ERR(tfm));
+		return false;
+	}
+
+	req = kpp_request_alloc(tfm, GFP_KERNEL);
+	if (!req)
+		goto free_kpp;
+
+	init_completion(&result.completion);
+
+	/* Set curve_id */
+	p.curve_id = ECC_CURVE_NIST_P256;
+	p.key_size = 32;
+	buf_len = crypto_ecdh_key_len(&p);
+	buf = kmalloc(buf_len, GFP_KERNEL);
+	if (!buf) {
+		pr_err("alg: kpp: Failed to allocate %d bytes for buf\n",
+		       buf_len);
+		goto free_req;
+	}
+
+	do {
+		if (tries++ >= max_tries)
+			goto free_all;
+
+		get_random_bytes(private_key, 32);
+
+		/* Set private Key */
+		p.key = (char *)private_key;
+		crypto_ecdh_encode_key(buf, buf_len, &p);
+		err = crypto_kpp_set_secret(tfm, buf, buf_len);
+		if (err)
+			goto free_all;
+
+		sg_init_one(&dst, tmp, 64);
+		kpp_request_set_output(req, &dst, 64);
+		kpp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
+					 ecdh_complete, &result);
+
+		err = crypto_kpp_generate_public_key(req);
+
+		if (err == -EINPROGRESS) {
+			wait_for_completion(&result.completion);
+			err = result.err;
+		}
+
+		/* Private key is not valid. Regenerate */
+		if (err == -EINVAL)
+			continue;
+
+		if (err < 0)
+			goto free_all;
+		else
+			break;
+
+	} while (true);
+
+	/* Keys are handed back in little endian as expected by Security
+	 * Manager Protocol
+	 */
+	swap_digits((u64 *)tmp, (u64 *)public_key, 4); /* x */
+	swap_digits((u64 *)&tmp[32], (u64 *)&public_key[32], 4); /* y */
+	swap_digits((u64 *)private_key, (u64 *)tmp, 4);
+	memcpy(private_key, tmp, 32);
+
+free_all:
+	kzfree(buf);
+free_req:
+	kpp_request_free(req);
+free_kpp:
+	crypto_free_kpp(tfm);
+	return (err == 0);
+}

net/bluetooth/ecdh_helper.h

+/*
+ * ECDH helper functions - KPP wrappings
+ *
+ * Copyright (C) 2017 Intel Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation;
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT OF THIRD PARTY RIGHTS.
+ * IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) AND AUTHOR(S) BE LIABLE FOR ANY
+ * CLAIM, OR ANY SPECIAL INDIRECT OR CONSEQUENTIAL DAMAGES, OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ * ALL LIABILITY, INCLUDING LIABILITY FOR INFRINGEMENT OF ANY PATENTS,
+ * COPYRIGHTS, TRADEMARKS OR OTHER RIGHTS, RELATING TO USE OF THIS
+ * SOFTWARE IS DISCLAIMED.
+ */
+#include <linux/types.h>
+
+bool compute_ecdh_secret(const u8 pub_a[64], const u8 priv_b[32],
+			 u8 secret[32]);
+bool generate_ecdh_keys(u8 public_key[64], u8 private_key[32]);

net/bluetooth/selftest.c

@@ -26,7 +26,7 @@
 #include <net/bluetooth/bluetooth.h>
 #include <net/bluetooth/hci_core.h>
 
-#include "ecc.h"
+#include "ecdh_helper.h"
 #include "smp.h"
 #include "selftest.h"
 
@@ -144,8 +144,8 @@ static int __init test_ecdh_sample(const u8 priv_a[32], const u8 priv_b[32],
 {
 	u8 dhkey_a[32], dhkey_b[32];
 
-	ecdh_shared_secret(pub_b, priv_a, dhkey_a);
-	ecdh_shared_secret(pub_a, priv_b, dhkey_b);
+	compute_ecdh_secret(pub_b, priv_a, dhkey_a);
+	compute_ecdh_secret(pub_a, priv_b, dhkey_b);
 
 	if (memcmp(dhkey_a, dhkey, 32))
 		return -EINVAL;

net/bluetooth/smp.c

@@ -31,7 +31,7 @@
 #include <net/bluetooth/l2cap.h>
 #include <net/bluetooth/mgmt.h>
 
-#include "ecc.h"
+#include "ecdh_helper.h"
 #include "smp.h"
 
 #define SMP_DEV(hdev) \
@@ -570,7 +570,7 @@ int smp_generate_oob(struct hci_dev *hdev, u8 hash[16], u8 rand[16])
 	} else {
 		while (true) {
 			/* Generate local key pair for Secure Connections */
-			if (!ecc_make_key(smp->local_pk, smp->local_sk))
+			if (!generate_ecdh_keys(smp->local_pk, smp->local_sk))
 				return -EIO;
 
 			/* This is unlikely, but we need to check that
@@ -1896,7 +1896,7 @@ static u8 sc_send_public_key(struct smp_chan *smp)
 	} else {
 		while (true) {
 			/* Generate local key pair for Secure Connections */
-			if (!ecc_make_key(smp->local_pk, smp->local_sk))
+			if (!generate_ecdh_keys(smp->local_pk, smp->local_sk))
 				return SMP_UNSPECIFIED;
 
 			/* This is unlikely, but we need to check that
@@ -2670,7 +2670,7 @@ static int smp_cmd_public_key(struct l2cap_conn *conn, struct sk_buff *skb)
 	SMP_DBG("Remote Public Key X: %32phN", smp->remote_pk);
 	SMP_DBG("Remote Public Key Y: %32phN", smp->remote_pk + 32);
 
-	if (!ecdh_shared_secret(smp->remote_pk, smp->local_sk, smp->dhkey))
+	if (!compute_ecdh_secret(smp->remote_pk, smp->local_sk, smp->dhkey))
 		return SMP_UNSPECIFIED;
 
 	SMP_DBG("DHKey %32phN", smp->dhkey);