diff options
Diffstat (limited to 'net/bluetooth/ecdh_helper.c')
| -rw-r--r-- | net/bluetooth/ecdh_helper.c | 203 |
1 files changed, 203 insertions, 0 deletions
diff --git a/net/bluetooth/ecdh_helper.c b/net/bluetooth/ecdh_helper.c new file mode 100644 index 0000000000..0efc93fdae --- /dev/null +++ b/net/bluetooth/ecdh_helper.c @@ -0,0 +1,203 @@ +/* + * 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> + +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]) +{ + DECLARE_CRYPTO_WAIT(result); + struct kpp_request *req; + u8 *tmp; + 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; + } + + 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, + crypto_req_done, &result); + err = crypto_kpp_compute_shared_secret(req); + err = crypto_wait_req(err, &result); + 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]) +{ + DECLARE_CRYPTO_WAIT(result); + struct kpp_request *req; + u8 *tmp; + 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; + } + + 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, + crypto_req_done, &result); + + err = crypto_kpp_generate_public_key(req); + err = crypto_wait_req(err, &result); + 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); +} |