diff options
Diffstat (limited to 'net/bluetooth/ecdh_helper.c')
| -rw-r--r-- | net/bluetooth/ecdh_helper.c | 223 |
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); +} |