1 files changed, 230 insertions, 0 deletions
diff --git a/net/bluetooth/ecdh_helper.c b/net/bluetooth/ecdh_helper.c
new file mode 100644
index 0000000..2155ce8
--- /dev/null
+++ b/net/bluetooth/ecdh_helper.c
@@ -0,0 +1,230 @@
+/*
+ * 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/scatterlist.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]);
+}
+
+/* compute_ecdh_secret() - function assumes that the private key was
+ *                         already set.
+ * @tfm:          KPP tfm handle allocated with crypto_alloc_kpp().
+ * @public_key:   pair's ecc public key.
+ * secret:        memory where the ecdh computed shared secret will be saved.
+ *
+ * Return: zero on success; error code in case of error.
+ */
+int compute_ecdh_secret(struct crypto_kpp *tfm, const u8 public_key[64],
+			u8 secret[32])
+{
+	struct kpp_request *req;
+	u8 *tmp;
+	struct ecdh_completion result;
+	struct scatterlist src, dst;
+	int err;
+
+	tmp = kmalloc(64, GFP_KERNEL);
+	if (!tmp)
+		return -ENOMEM;
+
+	req = kpp_request_alloc(tfm, GFP_KERNEL);
+	if (!req) {
+		err = -ENOMEM;
+		goto free_tmp;
+	}
+
+	init_completion(&result.completion);
+
+	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:
+	kpp_request_free(req);
+free_tmp:
+	kzfree(tmp);
+	return err;
+}
+
+/* set_ecdh_privkey() - set or generate ecc private key.
+ *
+ * Function generates an ecc private key in the crypto subsystem when receiving
+ * a NULL private key or sets the received key when not NULL.
+ *
+ * @tfm:           KPP tfm handle allocated with crypto_alloc_kpp().
+ * @private_key:   user's ecc private key. When not NULL, the key is expected
+ *                 in little endian format.
+ *
+ * Return: zero on success; error code in case of error.
+ */
+int set_ecdh_privkey(struct crypto_kpp *tfm, const u8 private_key[32])
+{
+	u8 *buf, *tmp = NULL;
+	unsigned int buf_len;
+	int err;
+	struct ecdh p = {0};
+
+	p.curve_id = ECC_CURVE_NIST_P256;
+
+	if (private_key) {
+		tmp = kmalloc(32, GFP_KERNEL);
+		if (!tmp)
+			return -ENOMEM;
+		swap_digits((u64 *)private_key, (u64 *)tmp, 4);
+		p.key = tmp;
+		p.key_size = 32;
+	}
+
+	buf_len = crypto_ecdh_key_len(&p);
+	buf = kmalloc(buf_len, GFP_KERNEL);
+	if (!buf) {
+		err = -ENOMEM;
+		goto free_tmp;
+	}
+
+	err = crypto_ecdh_encode_key(buf, buf_len, &p);
+	if (err)
+		goto free_all;
+
+	err = crypto_kpp_set_secret(tfm, buf, buf_len);
+	/* fall through */
+free_all:
+	kzfree(buf);
+free_tmp:
+	kzfree(tmp);
+	return err;
+}
+
+/* generate_ecdh_public_key() - function assumes that the private key was
+ *                              already set.
+ *
+ * @tfm:          KPP tfm handle allocated with crypto_alloc_kpp().
+ * @public_key:   memory where the computed ecc public key will be saved.
+ *
+ * Return: zero on success; error code in case of error.
+ */
+int generate_ecdh_public_key(struct crypto_kpp *tfm, u8 public_key[64])
+{
+	struct kpp_request *req;
+	u8 *tmp;
+	struct ecdh_completion result;
+	struct scatterlist dst;
+	int err;
+
+	tmp = kmalloc(64, GFP_KERNEL);
+	if (!tmp)
+		return -ENOMEM;
+
+	req = kpp_request_alloc(tfm, GFP_KERNEL);
+	if (!req) {
+		err = -ENOMEM;
+		goto free_tmp;
+	}
+
+	init_completion(&result.completion);
+	sg_init_one(&dst, tmp, 64);
+	kpp_request_set_input(req, NULL, 0);
+	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;
+	}
+	if (err < 0)
+		goto free_all;
+
+	/* The public key is handed back in little endian as expected by
+	 * the Security Manager Protocol.
+	 */
+	swap_digits((u64 *)tmp, (u64 *)public_key, 4); /* x */
+	swap_digits((u64 *)&tmp[32], (u64 *)&public_key[32], 4); /* y */
+
+free_all:
+	kpp_request_free(req);
+free_tmp:
+	kfree(tmp);
+	return err;
+}
+
+/* generate_ecdh_keys() - generate ecc key pair.
+ *
+ * @tfm:          KPP tfm handle allocated with crypto_alloc_kpp().
+ * @public_key:   memory where the computed ecc public key will be saved.
+ *
+ * Return: zero on success; error code in case of error.
+ */
+int generate_ecdh_keys(struct crypto_kpp *tfm, u8 public_key[64])
+{
+	int err;
+
+	err = set_ecdh_privkey(tfm, NULL);
+	if (err)
+		return err;
+
+	return generate_ecdh_public_key(tfm, public_key);
+}