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>

1 files changed, 223 insertions, 0 deletions

diff --git a/net/bluetooth/ecdh_helper.c b/net/bluetooth/ecdh_helper.c
new file mode 100644
index 000000000000..b6d9aa155485
--- /dev/null
+++ b/net/bluetooth/ecdh_helper.c
@@ -0,0 +1,223 @@
+/*
+ * 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);
+}