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This reverts commit c4741b2305
.
Crypto API self-tests no longer run at registration time and now
occur either at late_initcall or upon the first use.
Therefore the premise of the above commit no longer exists. Revert
it and subsequent additions of subsys_initcall and arch_initcall.
Note that lib/crypto calls will stay at subsys_initcall (or rather
downgraded from arch_initcall) because they may need to occur
before Crypto API registration.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
206 lines
5.5 KiB
C
206 lines
5.5 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* POLYVAL: hash function for HCTR2.
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*
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* Copyright (c) 2007 Nokia Siemens Networks - Mikko Herranen <mh1@iki.fi>
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* Copyright (c) 2009 Intel Corp.
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* Author: Huang Ying <ying.huang@intel.com>
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* Copyright 2021 Google LLC
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*/
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/*
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* Code based on crypto/ghash-generic.c
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*
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* POLYVAL is a keyed hash function similar to GHASH. POLYVAL uses a different
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* modulus for finite field multiplication which makes hardware accelerated
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* implementations on little-endian machines faster. POLYVAL is used in the
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* kernel to implement HCTR2, but was originally specified for AES-GCM-SIV
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* (RFC 8452).
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*
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* For more information see:
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* Length-preserving encryption with HCTR2:
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* https://eprint.iacr.org/2021/1441.pdf
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* AES-GCM-SIV: Nonce Misuse-Resistant Authenticated Encryption:
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* https://datatracker.ietf.org/doc/html/rfc8452
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*
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* Like GHASH, POLYVAL is not a cryptographic hash function and should
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* not be used outside of crypto modes explicitly designed to use POLYVAL.
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*
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* This implementation uses a convenient trick involving the GHASH and POLYVAL
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* fields. This trick allows multiplication in the POLYVAL field to be
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* implemented by using multiplication in the GHASH field as a subroutine. An
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* element of the POLYVAL field can be converted to an element of the GHASH
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* field by computing x*REVERSE(a), where REVERSE reverses the byte-ordering of
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* a. Similarly, an element of the GHASH field can be converted back to the
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* POLYVAL field by computing REVERSE(x^{-1}*a). For more information, see:
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* https://datatracker.ietf.org/doc/html/rfc8452#appendix-A
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*
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* By using this trick, we do not need to implement the POLYVAL field for the
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* generic implementation.
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*
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* Warning: this generic implementation is not intended to be used in practice
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* and is not constant time. For practical use, a hardware accelerated
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* implementation of POLYVAL should be used instead.
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*
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*/
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#include <crypto/gf128mul.h>
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#include <crypto/internal/hash.h>
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#include <crypto/polyval.h>
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#include <crypto/utils.h>
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#include <linux/errno.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/string.h>
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#include <linux/unaligned.h>
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struct polyval_tfm_ctx {
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struct gf128mul_4k *gf128;
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};
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struct polyval_desc_ctx {
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union {
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u8 buffer[POLYVAL_BLOCK_SIZE];
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be128 buffer128;
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};
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};
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static void copy_and_reverse(u8 dst[POLYVAL_BLOCK_SIZE],
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const u8 src[POLYVAL_BLOCK_SIZE])
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{
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u64 a = get_unaligned((const u64 *)&src[0]);
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u64 b = get_unaligned((const u64 *)&src[8]);
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put_unaligned(swab64(a), (u64 *)&dst[8]);
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put_unaligned(swab64(b), (u64 *)&dst[0]);
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}
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static int polyval_setkey(struct crypto_shash *tfm,
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const u8 *key, unsigned int keylen)
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{
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struct polyval_tfm_ctx *ctx = crypto_shash_ctx(tfm);
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be128 k;
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if (keylen != POLYVAL_BLOCK_SIZE)
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return -EINVAL;
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gf128mul_free_4k(ctx->gf128);
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BUILD_BUG_ON(sizeof(k) != POLYVAL_BLOCK_SIZE);
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copy_and_reverse((u8 *)&k, key);
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gf128mul_x_lle(&k, &k);
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ctx->gf128 = gf128mul_init_4k_lle(&k);
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memzero_explicit(&k, POLYVAL_BLOCK_SIZE);
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if (!ctx->gf128)
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return -ENOMEM;
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return 0;
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}
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static int polyval_init(struct shash_desc *desc)
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{
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struct polyval_desc_ctx *dctx = shash_desc_ctx(desc);
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memset(dctx, 0, sizeof(*dctx));
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return 0;
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}
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static int polyval_update(struct shash_desc *desc,
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const u8 *src, unsigned int srclen)
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{
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struct polyval_desc_ctx *dctx = shash_desc_ctx(desc);
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const struct polyval_tfm_ctx *ctx = crypto_shash_ctx(desc->tfm);
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u8 tmp[POLYVAL_BLOCK_SIZE];
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do {
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copy_and_reverse(tmp, src);
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crypto_xor(dctx->buffer, tmp, POLYVAL_BLOCK_SIZE);
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gf128mul_4k_lle(&dctx->buffer128, ctx->gf128);
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src += POLYVAL_BLOCK_SIZE;
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srclen -= POLYVAL_BLOCK_SIZE;
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} while (srclen >= POLYVAL_BLOCK_SIZE);
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return srclen;
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}
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static int polyval_finup(struct shash_desc *desc, const u8 *src,
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unsigned int len, u8 *dst)
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{
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struct polyval_desc_ctx *dctx = shash_desc_ctx(desc);
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if (len) {
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u8 tmp[POLYVAL_BLOCK_SIZE] = {};
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memcpy(tmp, src, len);
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polyval_update(desc, tmp, POLYVAL_BLOCK_SIZE);
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}
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copy_and_reverse(dst, dctx->buffer);
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return 0;
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}
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static int polyval_export(struct shash_desc *desc, void *out)
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{
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struct polyval_desc_ctx *dctx = shash_desc_ctx(desc);
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copy_and_reverse(out, dctx->buffer);
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return 0;
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}
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static int polyval_import(struct shash_desc *desc, const void *in)
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{
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struct polyval_desc_ctx *dctx = shash_desc_ctx(desc);
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copy_and_reverse(dctx->buffer, in);
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return 0;
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}
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static void polyval_exit_tfm(struct crypto_shash *tfm)
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{
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struct polyval_tfm_ctx *ctx = crypto_shash_ctx(tfm);
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gf128mul_free_4k(ctx->gf128);
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}
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static struct shash_alg polyval_alg = {
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.digestsize = POLYVAL_DIGEST_SIZE,
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.init = polyval_init,
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.update = polyval_update,
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.finup = polyval_finup,
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.setkey = polyval_setkey,
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.export = polyval_export,
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.import = polyval_import,
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.exit_tfm = polyval_exit_tfm,
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.statesize = sizeof(struct polyval_desc_ctx),
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.descsize = sizeof(struct polyval_desc_ctx),
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.base = {
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.cra_name = "polyval",
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.cra_driver_name = "polyval-generic",
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.cra_priority = 100,
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.cra_flags = CRYPTO_AHASH_ALG_BLOCK_ONLY,
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.cra_blocksize = POLYVAL_BLOCK_SIZE,
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.cra_ctxsize = sizeof(struct polyval_tfm_ctx),
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.cra_module = THIS_MODULE,
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},
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};
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static int __init polyval_mod_init(void)
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{
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return crypto_register_shash(&polyval_alg);
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}
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static void __exit polyval_mod_exit(void)
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{
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crypto_unregister_shash(&polyval_alg);
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}
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module_init(polyval_mod_init);
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module_exit(polyval_mod_exit);
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("POLYVAL hash function");
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MODULE_ALIAS_CRYPTO("polyval");
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MODULE_ALIAS_CRYPTO("polyval-generic");
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