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// SPDX-License-Identifier: MIT
/*
* fs-verity hash algorithms
*
* Copyright 2018 Google LLC
*
* Use of this source code is governed by an MIT-style
* license that can be found in the LICENSE file or at
* https://opensource.org/licenses/MIT.
*/
#include "lib_private.h"
#include <openssl/evp.h>
#include <stdlib.h>
#include <string.h>
/* ========== libcrypto (OpenSSL) wrappers ========== */
struct openssl_hash_ctx {
struct hash_ctx base; /* must be first */
EVP_MD_CTX *md_ctx;
const EVP_MD *md;
};
static void openssl_digest_init(struct hash_ctx *_ctx)
{
struct openssl_hash_ctx *ctx = (void *)_ctx;
int ret;
ret = EVP_DigestInit_ex(ctx->md_ctx, ctx->md, NULL);
BUG_ON(ret != 1);
}
static void openssl_digest_update(struct hash_ctx *_ctx,
const void *data, size_t size)
{
struct openssl_hash_ctx *ctx = (void *)_ctx;
int ret;
ret = EVP_DigestUpdate(ctx->md_ctx, data, size);
BUG_ON(ret != 1);
}
static void openssl_digest_final(struct hash_ctx *_ctx, u8 *digest)
{
struct openssl_hash_ctx *ctx = (void *)_ctx;
int ret;
ret = EVP_DigestFinal_ex(ctx->md_ctx, digest, NULL);
BUG_ON(ret != 1);
}
static void openssl_digest_ctx_free(struct hash_ctx *_ctx)
{
struct openssl_hash_ctx *ctx = (void *)_ctx;
/*
* OpenSSL 1.1.0 renamed EVP_MD_CTX_destroy() to EVP_MD_CTX_free() but
* kept the old name as a macro. Use the old name for compatibility
* with older OpenSSL versions.
*/
EVP_MD_CTX_destroy(ctx->md_ctx);
free(ctx);
}
static struct hash_ctx *
openssl_digest_ctx_create(const struct fsverity_hash_alg *alg, const EVP_MD *md)
{
struct openssl_hash_ctx *ctx;
ctx = libfsverity_zalloc(sizeof(*ctx));
if (!ctx)
return NULL;
ctx->base.alg = alg;
ctx->base.init = openssl_digest_init;
ctx->base.update = openssl_digest_update;
ctx->base.final = openssl_digest_final;
ctx->base.free = openssl_digest_ctx_free;
/*
* OpenSSL 1.1.0 renamed EVP_MD_CTX_create() to EVP_MD_CTX_new() but
* kept the old name as a macro. Use the old name for compatibility
* with older OpenSSL versions.
*/
ctx->md_ctx = EVP_MD_CTX_create();
if (!ctx->md_ctx) {
libfsverity_error_msg("failed to allocate EVP_MD_CTX");
goto err1;
}
ctx->md = md;
if (WARN_ON(EVP_MD_size(md) != alg->digest_size))
goto err2;
return &ctx->base;
err2:
EVP_MD_CTX_destroy(ctx->md_ctx);
err1:
free(ctx);
return NULL;
}
static struct hash_ctx *create_sha256_ctx(const struct fsverity_hash_alg *alg)
{
return openssl_digest_ctx_create(alg, EVP_sha256());
}
static struct hash_ctx *create_sha512_ctx(const struct fsverity_hash_alg *alg)
{
return openssl_digest_ctx_create(alg, EVP_sha512());
}
/* ========== Hash utilities ========== */
void libfsverity_hash_init(struct hash_ctx *ctx)
{
ctx->init(ctx);
}
void libfsverity_hash_update(struct hash_ctx *ctx, const void *data,
size_t size)
{
ctx->update(ctx, data, size);
}
void libfsverity_hash_final(struct hash_ctx *ctx, u8 *digest)
{
ctx->final(ctx, digest);
}
/* ->init(), ->update(), and ->final() all in one step */
void libfsverity_hash_full(struct hash_ctx *ctx, const void *data, size_t size,
u8 *digest)
{
libfsverity_hash_init(ctx);
libfsverity_hash_update(ctx, data, size);
libfsverity_hash_final(ctx, digest);
}
void libfsverity_free_hash_ctx(struct hash_ctx *ctx)
{
if (ctx)
ctx->free(ctx);
}
/* ========== Hash algorithm definitions ========== */
static const struct fsverity_hash_alg fsverity_hash_algs[] = {
[FS_VERITY_HASH_ALG_SHA256] = {
.name = "sha256",
.digest_size = 32,
.block_size = 64,
.create_ctx = create_sha256_ctx,
},
[FS_VERITY_HASH_ALG_SHA512] = {
.name = "sha512",
.digest_size = 64,
.block_size = 128,
.create_ctx = create_sha512_ctx,
},
};
LIBEXPORT u32
libfsverity_find_hash_alg_by_name(const char *name)
{
int i;
if (!name)
return 0;
for (i = 1; i < ARRAY_SIZE(fsverity_hash_algs); i++) {
if (fsverity_hash_algs[i].name &&
!strcmp(name, fsverity_hash_algs[i].name))
return i;
}
return 0;
}
const struct fsverity_hash_alg *libfsverity_find_hash_alg_by_num(u32 alg_num)
{
if (alg_num < ARRAY_SIZE(fsverity_hash_algs) &&
fsverity_hash_algs[alg_num].name)
return &fsverity_hash_algs[alg_num];
return NULL;
}
LIBEXPORT int
libfsverity_get_digest_size(u32 alg_num)
{
const struct fsverity_hash_alg *alg =
libfsverity_find_hash_alg_by_num(alg_num);
return alg ? alg->digest_size : -1;
}
LIBEXPORT const char *
libfsverity_get_hash_name(u32 alg_num)
{
const struct fsverity_hash_alg *alg =
libfsverity_find_hash_alg_by_num(alg_num);
return alg ? alg->name : NULL;
}
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