summaryrefslogtreecommitdiffstats
path: root/net/bluetooth/ecdh_helper.c
diff options
context:
space:
mode:
Diffstat (limited to '')
-rw-r--r--net/bluetooth/ecdh_helper.c228
1 files changed, 228 insertions, 0 deletions
diff --git a/net/bluetooth/ecdh_helper.c b/net/bluetooth/ecdh_helper.c
new file mode 100644
index 000000000..989401f11
--- /dev/null
+++ b/net/bluetooth/ecdh_helper.c
@@ -0,0 +1,228 @@
+/*
+ * 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:
+ kfree_sensitive(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};
+
+ 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:
+ kfree_sensitive(buf);
+free_tmp:
+ kfree_sensitive(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);
+}