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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Herbert Xu <herbert@gondor.apana.org.au>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        Ard Biesheuvel <ardb@kernel.org>,
        "Jason A. Donenfeld" <Jason@zx2c4.com>
Subject: [PATCH 5.15 008/145] lib/crypto: blake2s: move hmac construction into wireguard
Date:   Fri, 27 May 2022 10:48:29 +0200
Message-Id: <20220527084851.772743140@linuxfoundation.org>
In-Reply-To: <20220527084850.364560116@linuxfoundation.org>
References: <20220527084850.364560116@linuxfoundation.org>
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From: "Jason A. Donenfeld" <Jason@zx2c4.com>

commit d8d83d8ab0a453e17e68b3a3bed1f940c34b8646 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/wireguard/noise.c |   45 ++++++++++++++++++++++++++++++++++++------
 include/crypto/blake2s.h      |    3 --
 lib/crypto/blake2s-selftest.c |   31 ----------------------------
 lib/crypto/blake2s.c          |   37 ----------------------------------
 4 files changed, 39 insertions(+), 77 deletions(-)

--- a/drivers/net/wireguard/noise.c
+++ b/drivers/net/wireguard/noise.c
@@ -302,6 +302,41 @@ void wg_noise_set_static_identity_privat
 		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 *secon
 		 ((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 *secon
 
 	/* 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 *secon
 
 	/* 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:
--- a/include/crypto/blake2s.h
+++ b/include/crypto/blake2s.h
@@ -101,7 +101,4 @@ static inline void blake2s(u8 *out, cons
 	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 */
--- a/lib/crypto/blake2s-selftest.c
+++ b/lib/crypto/blake2s-selftest.c
@@ -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[][BLAKE
     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;
 }
--- a/lib/crypto/blake2s.c
+++ b/lib/crypto/blake2s.c
@@ -30,43 +30,6 @@ void blake2s_final(struct blake2s_state
 }
 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) &&