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d5c3b17898
On the quest to remove all VLAs from the kernel[1], this avoids VLAs
by just using the maximum allocation size (4 bytes) for stack arrays.
All the VLAs in ecc were either 3 or 4 bytes (or a multiple), so just
make it 4 bytes all the time. Initialization routines are adjusted to
check that ndigits does not end up larger than the arrays.
This includes a removal of the earlier attempt at this fix from
commit a963834b4742 ("crypto/ecc: Remove stack VLA usage")
[1] https://lkml.org/lkml/2018/3/7/621
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
95 lines
3.7 KiB
C
95 lines
3.7 KiB
C
/*
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* Copyright (c) 2013, Kenneth MacKay
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef _CRYPTO_ECC_H
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#define _CRYPTO_ECC_H
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#define ECC_CURVE_NIST_P192_DIGITS 3
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#define ECC_CURVE_NIST_P256_DIGITS 4
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#define ECC_MAX_DIGITS ECC_CURVE_NIST_P256_DIGITS
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#define ECC_DIGITS_TO_BYTES_SHIFT 3
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/**
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* ecc_is_key_valid() - Validate a given ECDH private key
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*
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* @curve_id: id representing the curve to use
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* @ndigits: curve's number of digits
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* @private_key: private key to be used for the given curve
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* @private_key_len: private key length
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*
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* Returns 0 if the key is acceptable, a negative value otherwise
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*/
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int ecc_is_key_valid(unsigned int curve_id, unsigned int ndigits,
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const u64 *private_key, unsigned int private_key_len);
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/**
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* ecc_gen_privkey() - Generates an ECC private key.
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* The private key is a random integer in the range 0 < random < n, where n is a
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* prime that is the order of the cyclic subgroup generated by the distinguished
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* point G.
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* @curve_id: id representing the curve to use
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* @ndigits: curve number of digits
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* @private_key: buffer for storing the generated private key
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*
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* Returns 0 if the private key was generated successfully, a negative value
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* if an error occurred.
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*/
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int ecc_gen_privkey(unsigned int curve_id, unsigned int ndigits, u64 *privkey);
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/**
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* ecc_make_pub_key() - Compute an ECC public key
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*
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* @curve_id: id representing the curve to use
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* @ndigits: curve's number of digits
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* @private_key: pregenerated private key for the given curve
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* @public_key: buffer for storing the generated public key
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*
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* Returns 0 if the public key was generated successfully, a negative value
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* if an error occurred.
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*/
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int ecc_make_pub_key(const unsigned int curve_id, unsigned int ndigits,
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const u64 *private_key, u64 *public_key);
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/**
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* crypto_ecdh_shared_secret() - Compute a shared secret
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*
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* @curve_id: id representing the curve to use
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* @ndigits: curve's number of digits
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* @private_key: private key of part A
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* @public_key: public key of counterpart B
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* @secret: buffer for storing the calculated shared secret
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*
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* Note: It is recommended that you hash the result of crypto_ecdh_shared_secret
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* before using it for symmetric encryption or HMAC.
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*
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* Returns 0 if the shared secret was generated successfully, a negative value
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* if an error occurred.
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*/
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int crypto_ecdh_shared_secret(unsigned int curve_id, unsigned int ndigits,
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const u64 *private_key, const u64 *public_key,
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u64 *secret);
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#endif
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