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228 lines
5.9 KiB
228 lines
5.9 KiB
/* |
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* ECDH helper functions - KPP wrappings |
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* |
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* Copyright (C) 2017 Intel Corporation |
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* |
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* This program is free software; you can redistribute it and/or modify |
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* it under the terms of the GNU General Public License version 2 as |
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* published by the Free Software Foundation; |
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* |
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS |
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* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT OF THIRD PARTY RIGHTS. |
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* IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) AND AUTHOR(S) BE LIABLE FOR ANY |
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* CLAIM, OR ANY SPECIAL INDIRECT OR CONSEQUENTIAL DAMAGES, OR ANY DAMAGES |
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN |
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF |
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. |
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* |
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* ALL LIABILITY, INCLUDING LIABILITY FOR INFRINGEMENT OF ANY PATENTS, |
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* COPYRIGHTS, TRADEMARKS OR OTHER RIGHTS, RELATING TO USE OF THIS |
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* SOFTWARE IS DISCLAIMED. |
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*/ |
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#include "ecdh_helper.h" |
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#include <linux/scatterlist.h> |
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#include <crypto/ecdh.h> |
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struct ecdh_completion { |
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struct completion completion; |
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int err; |
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}; |
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static void ecdh_complete(struct crypto_async_request *req, int err) |
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{ |
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struct ecdh_completion *res = req->data; |
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if (err == -EINPROGRESS) |
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return; |
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res->err = err; |
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complete(&res->completion); |
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} |
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static inline void swap_digits(u64 *in, u64 *out, unsigned int ndigits) |
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{ |
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int i; |
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for (i = 0; i < ndigits; i++) |
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out[i] = __swab64(in[ndigits - 1 - i]); |
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} |
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/* compute_ecdh_secret() - function assumes that the private key was |
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* already set. |
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* @tfm: KPP tfm handle allocated with crypto_alloc_kpp(). |
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* @public_key: pair's ecc public key. |
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* secret: memory where the ecdh computed shared secret will be saved. |
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* |
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* Return: zero on success; error code in case of error. |
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*/ |
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int compute_ecdh_secret(struct crypto_kpp *tfm, const u8 public_key[64], |
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u8 secret[32]) |
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{ |
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struct kpp_request *req; |
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u8 *tmp; |
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struct ecdh_completion result; |
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struct scatterlist src, dst; |
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int err; |
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tmp = kmalloc(64, GFP_KERNEL); |
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if (!tmp) |
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return -ENOMEM; |
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req = kpp_request_alloc(tfm, GFP_KERNEL); |
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if (!req) { |
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err = -ENOMEM; |
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goto free_tmp; |
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} |
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init_completion(&result.completion); |
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swap_digits((u64 *)public_key, (u64 *)tmp, 4); /* x */ |
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swap_digits((u64 *)&public_key[32], (u64 *)&tmp[32], 4); /* y */ |
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sg_init_one(&src, tmp, 64); |
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sg_init_one(&dst, secret, 32); |
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kpp_request_set_input(req, &src, 64); |
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kpp_request_set_output(req, &dst, 32); |
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kpp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG, |
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ecdh_complete, &result); |
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err = crypto_kpp_compute_shared_secret(req); |
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if (err == -EINPROGRESS) { |
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wait_for_completion(&result.completion); |
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err = result.err; |
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} |
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if (err < 0) { |
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pr_err("alg: ecdh: compute shared secret failed. err %d\n", |
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err); |
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goto free_all; |
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} |
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swap_digits((u64 *)secret, (u64 *)tmp, 4); |
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memcpy(secret, tmp, 32); |
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free_all: |
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kpp_request_free(req); |
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free_tmp: |
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kfree_sensitive(tmp); |
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return err; |
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} |
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/* set_ecdh_privkey() - set or generate ecc private key. |
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* |
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* Function generates an ecc private key in the crypto subsystem when receiving |
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* a NULL private key or sets the received key when not NULL. |
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* |
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* @tfm: KPP tfm handle allocated with crypto_alloc_kpp(). |
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* @private_key: user's ecc private key. When not NULL, the key is expected |
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* in little endian format. |
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* |
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* Return: zero on success; error code in case of error. |
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*/ |
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int set_ecdh_privkey(struct crypto_kpp *tfm, const u8 private_key[32]) |
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{ |
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u8 *buf, *tmp = NULL; |
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unsigned int buf_len; |
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int err; |
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struct ecdh p = {0}; |
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if (private_key) { |
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tmp = kmalloc(32, GFP_KERNEL); |
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if (!tmp) |
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return -ENOMEM; |
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swap_digits((u64 *)private_key, (u64 *)tmp, 4); |
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p.key = tmp; |
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p.key_size = 32; |
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} |
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buf_len = crypto_ecdh_key_len(&p); |
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buf = kmalloc(buf_len, GFP_KERNEL); |
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if (!buf) { |
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err = -ENOMEM; |
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goto free_tmp; |
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} |
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err = crypto_ecdh_encode_key(buf, buf_len, &p); |
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if (err) |
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goto free_all; |
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err = crypto_kpp_set_secret(tfm, buf, buf_len); |
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/* fall through */ |
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free_all: |
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kfree_sensitive(buf); |
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free_tmp: |
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kfree_sensitive(tmp); |
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return err; |
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} |
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/* generate_ecdh_public_key() - function assumes that the private key was |
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* already set. |
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* |
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* @tfm: KPP tfm handle allocated with crypto_alloc_kpp(). |
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* @public_key: memory where the computed ecc public key will be saved. |
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* |
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* Return: zero on success; error code in case of error. |
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*/ |
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int generate_ecdh_public_key(struct crypto_kpp *tfm, u8 public_key[64]) |
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{ |
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struct kpp_request *req; |
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u8 *tmp; |
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struct ecdh_completion result; |
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struct scatterlist dst; |
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int err; |
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tmp = kmalloc(64, GFP_KERNEL); |
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if (!tmp) |
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return -ENOMEM; |
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req = kpp_request_alloc(tfm, GFP_KERNEL); |
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if (!req) { |
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err = -ENOMEM; |
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goto free_tmp; |
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} |
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init_completion(&result.completion); |
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sg_init_one(&dst, tmp, 64); |
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kpp_request_set_input(req, NULL, 0); |
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kpp_request_set_output(req, &dst, 64); |
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kpp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG, |
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ecdh_complete, &result); |
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err = crypto_kpp_generate_public_key(req); |
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if (err == -EINPROGRESS) { |
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wait_for_completion(&result.completion); |
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err = result.err; |
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} |
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if (err < 0) |
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goto free_all; |
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/* The public key is handed back in little endian as expected by |
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* the Security Manager Protocol. |
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*/ |
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swap_digits((u64 *)tmp, (u64 *)public_key, 4); /* x */ |
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swap_digits((u64 *)&tmp[32], (u64 *)&public_key[32], 4); /* y */ |
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free_all: |
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kpp_request_free(req); |
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free_tmp: |
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kfree(tmp); |
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return err; |
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} |
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/* generate_ecdh_keys() - generate ecc key pair. |
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* |
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* @tfm: KPP tfm handle allocated with crypto_alloc_kpp(). |
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* @public_key: memory where the computed ecc public key will be saved. |
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* |
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* Return: zero on success; error code in case of error. |
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*/ |
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int generate_ecdh_keys(struct crypto_kpp *tfm, u8 public_key[64]) |
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{ |
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int err; |
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err = set_ecdh_privkey(tfm, NULL); |
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if (err) |
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return err; |
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return generate_ecdh_public_key(tfm, public_key); |
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}
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