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lib/crypto: blake2s: move hmac construction into wireguard

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Basically nobody should use blake2s in an HMAC construction; it already
has a keyed variant. But unfortunately for historical reasons, Noise,
used by WireGuard, uses HKDF quite strictly, which means we have to use
this. Because this really shouldn't be used by others, this commit moves
it into wireguard's noise.c locally, so that kernels that aren't using
WireGuard don't get this superfluous code baked in. On m68k systems,
this shaves off ~314 bytes.

Cc: Herbert Xu <herbert@gondor.apana.org.au>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
This commit is contained in:
Jason A. Donenfeld 2022-01-11 14:37:41 +01:00
parent e56e189855
commit d8d83d8ab0
4 changed files with 39 additions and 77 deletions
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45
drivers/net/wireguard/noise.c
View File

@ -302,6 +302,41 @@ void wg_noise_set_static_identity_private_key(
static_identity->static_public, private_key);
}
static void hmac(u8 *out, const u8 *in, const u8 *key, const size_t inlen, const size_t keylen)
{
struct blake2s_state state;
u8 x_key[BLAKE2S_BLOCK_SIZE] __aligned(__alignof__(u32)) = { 0 };
u8 i_hash[BLAKE2S_HASH_SIZE] __aligned(__alignof__(u32));
int i;
if (keylen > BLAKE2S_BLOCK_SIZE) {
blake2s_init(&state, BLAKE2S_HASH_SIZE);
blake2s_update(&state, key, keylen);
blake2s_final(&state, x_key);
} else
memcpy(x_key, key, keylen);
for (i = 0; i < BLAKE2S_BLOCK_SIZE; ++i)
x_key[i] ^= 0x36;
blake2s_init(&state, BLAKE2S_HASH_SIZE);
blake2s_update(&state, x_key, BLAKE2S_BLOCK_SIZE);
blake2s_update(&state, in, inlen);
blake2s_final(&state, i_hash);
for (i = 0; i < BLAKE2S_BLOCK_SIZE; ++i)
x_key[i] ^= 0x5c ^ 0x36;
blake2s_init(&state, BLAKE2S_HASH_SIZE);
blake2s_update(&state, x_key, BLAKE2S_BLOCK_SIZE);
blake2s_update(&state, i_hash, BLAKE2S_HASH_SIZE);
blake2s_final(&state, i_hash);
memcpy(out, i_hash, BLAKE2S_HASH_SIZE);
memzero_explicit(x_key, BLAKE2S_BLOCK_SIZE);
memzero_explicit(i_hash, BLAKE2S_HASH_SIZE);
}
/* This is Hugo Krawczyk's HKDF:
* - https://eprint.iacr.org/2010/264.pdf
* - https://tools.ietf.org/html/rfc5869
@ -322,14 +357,14 @@ static void kdf(u8 *first_dst, u8 *second_dst, u8 *third_dst, const u8 *data,
((third_len || third_dst) && (!second_len || !second_dst))));
/* Extract entropy from data into secret */
blake2s256_hmac(secret, data, chaining_key, data_len, NOISE_HASH_LEN);
hmac(secret, data, chaining_key, data_len, NOISE_HASH_LEN);
if (!first_dst || !first_len)
goto out;
/* Expand first key: key = secret, data = 0x1 */
output[0] = 1;
blake2s256_hmac(output, output, secret, 1, BLAKE2S_HASH_SIZE);
hmac(output, output, secret, 1, BLAKE2S_HASH_SIZE);
memcpy(first_dst, output, first_len);
if (!second_dst || !second_len)
@ -337,8 +372,7 @@ static void kdf(u8 *first_dst, u8 *second_dst, u8 *third_dst, const u8 *data,
/* Expand second key: key = secret, data = first-key || 0x2 */
output[BLAKE2S_HASH_SIZE] = 2;
blake2s256_hmac(output, output, secret, BLAKE2S_HASH_SIZE + 1,
BLAKE2S_HASH_SIZE);
hmac(output, output, secret, BLAKE2S_HASH_SIZE + 1, BLAKE2S_HASH_SIZE);
memcpy(second_dst, output, second_len);
if (!third_dst || !third_len)
@ -346,8 +380,7 @@ static void kdf(u8 *first_dst, u8 *second_dst, u8 *third_dst, const u8 *data,
/* Expand third key: key = secret, data = second-key || 0x3 */
output[BLAKE2S_HASH_SIZE] = 3;
blake2s256_hmac(output, output, secret, BLAKE2S_HASH_SIZE + 1,
BLAKE2S_HASH_SIZE);
hmac(output, output, secret, BLAKE2S_HASH_SIZE + 1, BLAKE2S_HASH_SIZE);
memcpy(third_dst, output, third_len);
out:

3
include/crypto/blake2s.h
View File

@ -101,7 +101,4 @@ static inline void blake2s(u8 *out, const u8 *in, const u8 *key,
blake2s_final(&state, out);
}
void blake2s256_hmac(u8 *out, const u8 *in, const u8 *key, const size_t inlen,
const size_t keylen);
#endif /* _CRYPTO_BLAKE2S_H */

31
lib/crypto/blake2s-selftest.c
View File

@ -15,7 +15,6 @@
* #include <stdio.h>
*
* #include <openssl/evp.h>
* #include <openssl/hmac.h>
*
* #define BLAKE2S_TESTVEC_COUNT 256
*
@ -58,16 +57,6 @@
* }
* printf("};\n\n");
*
* printf("static const u8 blake2s_hmac_testvecs[][BLAKE2S_HASH_SIZE] __initconst = {\n");
*
* HMAC(EVP_blake2s256(), key, sizeof(key), buf, sizeof(buf), hash, NULL);
* print_vec(hash, BLAKE2S_OUTBYTES);
*
* HMAC(EVP_blake2s256(), buf, sizeof(buf), key, sizeof(key), hash, NULL);
* print_vec(hash, BLAKE2S_OUTBYTES);
*
* printf("};\n");
*
* return 0;
*}
*/
@ -554,15 +543,6 @@ static const u8 blake2s_testvecs[][BLAKE2S_HASH_SIZE] __initconst = {
0xd6, 0x98, 0x6b, 0x07, 0x10, 0x65, 0x52, 0x65, },
};
static const u8 blake2s_hmac_testvecs[][BLAKE2S_HASH_SIZE] __initconst = {
{ 0xce, 0xe1, 0x57, 0x69, 0x82, 0xdc, 0xbf, 0x43, 0xad, 0x56, 0x4c, 0x70,
0xed, 0x68, 0x16, 0x96, 0xcf, 0xa4, 0x73, 0xe8, 0xe8, 0xfc, 0x32, 0x79,
0x08, 0x0a, 0x75, 0x82, 0xda, 0x3f, 0x05, 0x11, },
{ 0x77, 0x2f, 0x0c, 0x71, 0x41, 0xf4, 0x4b, 0x2b, 0xb3, 0xc6, 0xb6, 0xf9,
0x60, 0xde, 0xe4, 0x52, 0x38, 0x66, 0xe8, 0xbf, 0x9b, 0x96, 0xc4, 0x9f,
0x60, 0xd9, 0x24, 0x37, 0x99, 0xd6, 0xec, 0x31, },
};
bool __init blake2s_selftest(void)
{
u8 key[BLAKE2S_KEY_SIZE];
@ -607,16 +587,5 @@ bool __init blake2s_selftest(void)
}
}
if (success) {
blake2s256_hmac(hash, buf, key, sizeof(buf), sizeof(key));
success &= !memcmp(hash, blake2s_hmac_testvecs[0], BLAKE2S_HASH_SIZE);
blake2s256_hmac(hash, key, buf, sizeof(key), sizeof(buf));
success &= !memcmp(hash, blake2s_hmac_testvecs[1], BLAKE2S_HASH_SIZE);
if (!success)
pr_err("blake2s256_hmac self-test: FAIL\n");
}
return success;
}

37
lib/crypto/blake2s.c
View File

@ -30,43 +30,6 @@ void blake2s_final(struct blake2s_state *state, u8 *out)
}
EXPORT_SYMBOL(blake2s_final);
void blake2s256_hmac(u8 *out, const u8 *in, const u8 *key, const size_t inlen,
const size_t keylen)
{
struct blake2s_state state;
u8 x_key[BLAKE2S_BLOCK_SIZE] __aligned(__alignof__(u32)) = { 0 };
u8 i_hash[BLAKE2S_HASH_SIZE] __aligned(__alignof__(u32));
int i;
if (keylen > BLAKE2S_BLOCK_SIZE) {
blake2s_init(&state, BLAKE2S_HASH_SIZE);
blake2s_update(&state, key, keylen);
blake2s_final(&state, x_key);
} else
memcpy(x_key, key, keylen);
for (i = 0; i < BLAKE2S_BLOCK_SIZE; ++i)
x_key[i] ^= 0x36;
blake2s_init(&state, BLAKE2S_HASH_SIZE);
blake2s_update(&state, x_key, BLAKE2S_BLOCK_SIZE);
blake2s_update(&state, in, inlen);
blake2s_final(&state, i_hash);
for (i = 0; i < BLAKE2S_BLOCK_SIZE; ++i)
x_key[i] ^= 0x5c ^ 0x36;
blake2s_init(&state, BLAKE2S_HASH_SIZE);
blake2s_update(&state, x_key, BLAKE2S_BLOCK_SIZE);
blake2s_update(&state, i_hash, BLAKE2S_HASH_SIZE);
blake2s_final(&state, i_hash);
memcpy(out, i_hash, BLAKE2S_HASH_SIZE);
memzero_explicit(x_key, BLAKE2S_BLOCK_SIZE);
memzero_explicit(i_hash, BLAKE2S_HASH_SIZE);
}
EXPORT_SYMBOL(blake2s256_hmac);
static int __init blake2s_mod_init(void)
{
if (!IS_ENABLED(CONFIG_CRYPTO_MANAGER_DISABLE_TESTS) &&