lib/crypto: tests: Add KUnit tests for POLYVAL

Add a test suite for the POLYVAL library, including:

- All the standard tests and the benchmark from hash-test-template.h
- Comparison with a test vector from the RFC
- Test with key and message containing all one bits
- Additional tests related to the key struct

Reviewed-by: Ard Biesheuvel <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Eric Biggers <[e-mail]>

lib/crypto/tests/Kconfig

···
 	help
 	  KUnit tests for the Poly1305 library functions.
 
+config CRYPTO_LIB_POLYVAL_KUNIT_TEST
+	tristate "KUnit tests for POLYVAL" if !KUNIT_ALL_TESTS
+	depends on KUNIT
+	default KUNIT_ALL_TESTS || CRYPTO_SELFTESTS
+	select CRYPTO_LIB_BENCHMARK_VISIBLE
+	select CRYPTO_LIB_POLYVAL
+	help
+	  KUnit tests for the POLYVAL library functions.
+
 config CRYPTO_LIB_SHA1_KUNIT_TEST
 	tristate "KUnit tests for SHA-1" if !KUNIT_ALL_TESTS
 	depends on KUNIT

lib/crypto/tests/Makefile

···
 obj-$(CONFIG_CRYPTO_LIB_CURVE25519_KUNIT_TEST) += curve25519_kunit.o
 obj-$(CONFIG_CRYPTO_LIB_MD5_KUNIT_TEST) += md5_kunit.o
 obj-$(CONFIG_CRYPTO_LIB_POLY1305_KUNIT_TEST) += poly1305_kunit.o
+obj-$(CONFIG_CRYPTO_LIB_POLYVAL_KUNIT_TEST) += polyval_kunit.o
 obj-$(CONFIG_CRYPTO_LIB_SHA1_KUNIT_TEST) += sha1_kunit.o
 obj-$(CONFIG_CRYPTO_LIB_SHA256_KUNIT_TEST) += sha224_kunit.o sha256_kunit.o
 obj-$(CONFIG_CRYPTO_LIB_SHA512_KUNIT_TEST) += sha384_kunit.o sha512_kunit.o

lib/crypto/tests/polyval-testvecs.h

···
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/* This file was generated by: ./scripts/crypto/gen-hash-testvecs.py polyval */
+
+static const struct {
+	size_t data_len;
+	u8 digest[POLYVAL_DIGEST_SIZE];
+} hash_testvecs[] = {
+	{
+		.data_len = 0,
+		.digest = {
+			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		},
+	},
+	{
+		.data_len = 1,
+		.digest = {
+			0xb5, 0x51, 0x69, 0x89, 0xd4, 0x3c, 0x59, 0xca,
+			0x6a, 0x1c, 0x2a, 0xe9, 0xa1, 0x9c, 0x6c, 0x83,
+		},
+	},
+	{
+		.data_len = 2,
+		.digest = {
+			0xf4, 0x50, 0xaf, 0x07, 0xda, 0x42, 0xa7, 0x41,
+			0x4d, 0x24, 0x88, 0x87, 0xe3, 0x40, 0x73, 0x7c,
+		},
+	},
+	{
+		.data_len = 3,
+		.digest = {
+			0x9e, 0x88, 0x78, 0x71, 0x4c, 0x55, 0x87, 0xe8,
+			0xb4, 0x96, 0x3d, 0x56, 0xc8, 0xb2, 0xe1, 0x68,
+		},
+	},
+	{
+		.data_len = 16,
+		.digest = {
+			0x9e, 0x81, 0x37, 0x8f, 0x49, 0xf7, 0xa2, 0xe4,
+			0x04, 0x45, 0x12, 0x78, 0x45, 0x42, 0x27, 0xad,
+		},
+	},
+	{
+		.data_len = 32,
+		.digest = {
+			0x60, 0x19, 0xd0, 0xa4, 0xf0, 0xde, 0x9e, 0xe7,
+			0x6a, 0x89, 0x1a, 0xea, 0x80, 0x14, 0xa9, 0xa3,
+		},
+	},
+	{
+		.data_len = 48,
+		.digest = {
+			0x0c, 0xa2, 0x70, 0x4d, 0x7c, 0x89, 0xac, 0x41,
+			0xc2, 0x9e, 0x0d, 0x07, 0x07, 0x6a, 0x7f, 0xd5,
+		},
+	},
+	{
+		.data_len = 49,
+		.digest = {
+			0x91, 0xd3, 0xa9, 0x5c, 0x79, 0x3d, 0x6b, 0x84,
+			0x99, 0x54, 0xa7, 0xb4, 0x06, 0x66, 0xfd, 0x1c,
+		},
+	},
+	{
+		.data_len = 63,
+		.digest = {
+			0x29, 0x37, 0xb8, 0xe5, 0xd8, 0x27, 0x4d, 0xfb,
+			0x83, 0x4f, 0x67, 0xf7, 0xf9, 0xc1, 0x0a, 0x9d,
+		},
+	},
+	{
+		.data_len = 64,
+		.digest = {
+			0x17, 0xa9, 0x06, 0x2c, 0xf3, 0xe8, 0x2e, 0xa6,
+			0x6b, 0xb2, 0x1f, 0x5d, 0x94, 0x3c, 0x02, 0xa2,
+		},
+	},
+	{
+		.data_len = 65,
+		.digest = {
+			0x7c, 0x80, 0x74, 0xd7, 0xa1, 0x37, 0x30, 0x64,
+			0x3b, 0xa4, 0xa3, 0x98, 0xde, 0x47, 0x10, 0x23,
+		},
+	},
+	{
+		.data_len = 127,
+		.digest = {
+			0x27, 0x3a, 0xcf, 0xf5, 0xaf, 0x9f, 0xd8, 0xd8,
+			0x2d, 0x6a, 0x91, 0xfb, 0xb8, 0xfa, 0xbe, 0x0c,
+		},
+	},
+	{
+		.data_len = 128,
+		.digest = {
+			0x97, 0x6e, 0xc4, 0xbe, 0x6b, 0x15, 0xa6, 0x7c,
+			0xc4, 0xa2, 0xb8, 0x0a, 0x0e, 0x9c, 0xc7, 0x3a,
+		},
+	},
+	{
+		.data_len = 129,
+		.digest = {
+			0x2b, 0xc3, 0x98, 0xba, 0x6e, 0x42, 0xf8, 0x18,
+			0x85, 0x69, 0x15, 0x37, 0x10, 0x60, 0xe6, 0xac,
+		},
+	},
+	{
+		.data_len = 256,
+		.digest = {
+			0x88, 0x21, 0x77, 0x89, 0xd7, 0x93, 0x90, 0xfc,
+			0xf3, 0xb0, 0xe3, 0xfb, 0x14, 0xe2, 0xcf, 0x74,
+		},
+	},
+	{
+		.data_len = 511,
+		.digest = {
+			0x66, 0x3d, 0x3e, 0x08, 0xa0, 0x49, 0x81, 0x68,
+			0x3e, 0x3b, 0xc8, 0x80, 0x55, 0xd4, 0x15, 0xe9,
+		},
+	},
+	{
+		.data_len = 513,
+		.digest = {
+			0x05, 0xf5, 0x06, 0x66, 0xe7, 0x11, 0x08, 0x84,
+			0xff, 0x94, 0x50, 0x85, 0x65, 0x95, 0x2a, 0x20,
+		},
+	},
+	{
+		.data_len = 1000,
+		.digest = {
+			0xd3, 0xa0, 0x51, 0x69, 0xb5, 0x38, 0xae, 0x1b,
+			0xe1, 0xa2, 0x89, 0xc6, 0x8d, 0x2b, 0x62, 0x37,
+		},
+	},
+	{
+		.data_len = 3333,
+		.digest = {
+			0x37, 0x6d, 0x6a, 0x14, 0xdc, 0xa5, 0x37, 0xfc,
+			0xfe, 0x67, 0x76, 0xb2, 0x64, 0x68, 0x64, 0x05,
+		},
+	},
+	{
+		.data_len = 4096,
+		.digest = {
+			0xe3, 0x12, 0x0c, 0x58, 0x46, 0x45, 0x27, 0x7a,
+			0x0e, 0xa2, 0xfa, 0x2c, 0x35, 0x73, 0x6c, 0x94,
+		},
+	},
+	{
+		.data_len = 4128,
+		.digest = {
+			0x63, 0x0d, 0xa1, 0xbc, 0x6e, 0x3e, 0xd3, 0x1d,
+			0x28, 0x52, 0xd2, 0xf4, 0x30, 0x2d, 0xff, 0xc4,
+		},
+	},
+	{
+		.data_len = 4160,
+		.digest = {
+			0xb2, 0x91, 0x49, 0xe2, 0x02, 0x98, 0x00, 0x79,
+			0x71, 0xb9, 0xd7, 0xd4, 0xb5, 0x94, 0x6d, 0x7d,
+		},
+	},
+	{
+		.data_len = 4224,
+		.digest = {
+			0x58, 0x96, 0x48, 0x69, 0x05, 0x17, 0xe1, 0x6d,
+			0xbc, 0xf2, 0x3d, 0x10, 0x96, 0x00, 0x74, 0x58,
+		},
+	},
+	{
+		.data_len = 16384,
+		.digest = {
+			0x99, 0x3c, 0xcb, 0x4d, 0x64, 0xc9, 0xa9, 0x41,
+			0x52, 0x93, 0xfd, 0x65, 0xc4, 0xcc, 0xa5, 0xe5,
+		},
+	},
+};
+
+static const u8 hash_testvec_consolidated[POLYVAL_DIGEST_SIZE] = {
+	0xdf, 0x68, 0x52, 0x99, 0x92, 0xc3, 0xe8, 0x88,
+	0x29, 0x13, 0xc8, 0x35, 0x67, 0xa3, 0xd3, 0xad,
+};
+
+static const u8 polyval_allones_hashofhashes[POLYVAL_DIGEST_SIZE] = {
+	0xd5, 0xf7, 0xfd, 0xb2, 0xa6, 0xef, 0x0b, 0x85,
+	0x0d, 0x0a, 0x06, 0x10, 0xbc, 0x64, 0x94, 0x73,
+};

lib/crypto/tests/polyval_kunit.c

···
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright 2025 Google LLC
+ */
+#include <crypto/polyval.h>
+#include "polyval-testvecs.h"
+
+/*
+ * A fixed key used when presenting POLYVAL as an unkeyed hash function in order
+ * to reuse hash-test-template.h.  At the beginning of the test suite, this is
+ * initialized to a key prepared from bytes generated from a fixed seed.
+ */
+static struct polyval_key test_key;
+
+static void polyval_init_withtestkey(struct polyval_ctx *ctx)
+{
+	polyval_init(ctx, &test_key);
+}
+
+static void polyval_withtestkey(const u8 *data, size_t len,
+				u8 out[POLYVAL_BLOCK_SIZE])
+{
+	polyval(&test_key, data, len, out);
+}
+
+/* Generate the HASH_KUNIT_CASES using hash-test-template.h. */
+#define HASH polyval_withtestkey
+#define HASH_CTX polyval_ctx
+#define HASH_SIZE POLYVAL_BLOCK_SIZE
+#define HASH_INIT polyval_init_withtestkey
+#define HASH_UPDATE polyval_update
+#define HASH_FINAL polyval_final
+#include "hash-test-template.h"
+
+/*
+ * Test an example from RFC8452 ("AES-GCM-SIV: Nonce Misuse-Resistant
+ * Authenticated Encryption") to ensure compatibility with that.
+ */
+static void test_polyval_rfc8452_testvec(struct kunit *test)
+{
+	static const u8 raw_key[POLYVAL_BLOCK_SIZE] =
+		"\x31\x07\x28\xd9\x91\x1f\x1f\x38"
+		"\x37\xb2\x43\x16\xc3\xfa\xb9\xa0";
+	static const u8 data[48] =
+		"\x65\x78\x61\x6d\x70\x6c\x65\x00"
+		"\x00\x00\x00\x00\x00\x00\x00\x00"
+		"\x48\x65\x6c\x6c\x6f\x20\x77\x6f"
+		"\x72\x6c\x64\x00\x00\x00\x00\x00"
+		"\x38\x00\x00\x00\x00\x00\x00\x00"
+		"\x58\x00\x00\x00\x00\x00\x00\x00";
+	static const u8 expected_hash[POLYVAL_BLOCK_SIZE] =
+		"\xad\x7f\xcf\x0b\x51\x69\x85\x16"
+		"\x62\x67\x2f\x3c\x5f\x95\x13\x8f";
+	u8 hash[POLYVAL_BLOCK_SIZE];
+	struct polyval_key key;
+
+	polyval_preparekey(&key, raw_key);
+	polyval(&key, data, sizeof(data), hash);
+	KUNIT_ASSERT_MEMEQ(test, hash, expected_hash, sizeof(hash));
+}
+
+/*
+ * Test a key and messages containing all one bits.  This is useful to detect
+ * overflow bugs in implementations that emulate carryless multiplication using
+ * a series of standard multiplications with the bits spread out.
+ */
+static void test_polyval_allones_key_and_message(struct kunit *test)
+{
+	struct polyval_key key;
+	struct polyval_ctx hashofhashes_ctx;
+	u8 hash[POLYVAL_BLOCK_SIZE];
+
+	static_assert(TEST_BUF_LEN >= 4096);
+	memset(test_buf, 0xff, 4096);
+
+	polyval_preparekey(&key, test_buf);
+	polyval_init(&hashofhashes_ctx, &key);
+	for (size_t len = 0; len <= 4096; len += 16) {
+		polyval(&key, test_buf, len, hash);
+		polyval_update(&hashofhashes_ctx, hash, sizeof(hash));
+	}
+	polyval_final(&hashofhashes_ctx, hash);
+	KUNIT_ASSERT_MEMEQ(test, hash, polyval_allones_hashofhashes,
+			   sizeof(hash));
+}
+
+#define MAX_LEN_FOR_KEY_CHECK 1024
+
+/*
+ * Given two prepared keys which should be identical (but may differ in
+ * alignment and/or whether they are followed by a guard page or not), verify
+ * that they produce consistent results on various data lengths.
+ */
+static void check_key_consistency(struct kunit *test,
+				  const struct polyval_key *key1,
+				  const struct polyval_key *key2)
+{
+	u8 *data = test_buf;
+	u8 hash1[POLYVAL_BLOCK_SIZE];
+	u8 hash2[POLYVAL_BLOCK_SIZE];
+
+	rand_bytes(data, MAX_LEN_FOR_KEY_CHECK);
+	KUNIT_ASSERT_MEMEQ(test, key1, key2, sizeof(*key1));
+
+	for (int i = 0; i < 100; i++) {
+		size_t len = rand_length(MAX_LEN_FOR_KEY_CHECK);
+
+		polyval(key1, data, len, hash1);
+		polyval(key2, data, len, hash2);
+		KUNIT_ASSERT_MEMEQ(test, hash1, hash2, sizeof(hash1));
+	}
+}
+
+/* Test that no buffer overreads occur on either raw_key or polyval_key. */
+static void test_polyval_with_guarded_key(struct kunit *test)
+{
+	u8 raw_key[POLYVAL_BLOCK_SIZE];
+	u8 *guarded_raw_key = &test_buf[TEST_BUF_LEN - sizeof(raw_key)];
+	struct polyval_key key1, key2;
+	struct polyval_key *guarded_key =
+		(struct polyval_key *)&test_buf[TEST_BUF_LEN - sizeof(key1)];
+
+	/* Prepare with regular buffers. */
+	rand_bytes(raw_key, sizeof(raw_key));
+	polyval_preparekey(&key1, raw_key);
+
+	/* Prepare with guarded raw_key, then check that it works. */
+	memcpy(guarded_raw_key, raw_key, sizeof(raw_key));
+	polyval_preparekey(&key2, guarded_raw_key);
+	check_key_consistency(test, &key1, &key2);
+
+	/* Prepare guarded polyval_key, then check that it works. */
+	polyval_preparekey(guarded_key, raw_key);
+	check_key_consistency(test, &key1, guarded_key);
+}
+
+/*
+ * Test that polyval_key only needs to be aligned to
+ * __alignof__(struct polyval_key), i.e. 8 bytes.  The assembly code may prefer
+ * 16-byte or higher alignment, but it musn't require it.
+ */
+static void test_polyval_with_minimally_aligned_key(struct kunit *test)
+{
+	u8 raw_key[POLYVAL_BLOCK_SIZE];
+	struct polyval_key key;
+	struct polyval_key *minaligned_key =
+		(struct polyval_key *)&test_buf[MAX_LEN_FOR_KEY_CHECK +
+						__alignof__(struct polyval_key)];
+
+	KUNIT_ASSERT_TRUE(test, IS_ALIGNED((uintptr_t)minaligned_key,
+					   __alignof__(struct polyval_key)));
+	KUNIT_ASSERT_TRUE(test,
+			  !IS_ALIGNED((uintptr_t)minaligned_key,
+				      2 * __alignof__(struct polyval_key)));
+
+	rand_bytes(raw_key, sizeof(raw_key));
+	polyval_preparekey(&key, raw_key);
+	polyval_preparekey(minaligned_key, raw_key);
+	check_key_consistency(test, &key, minaligned_key);
+}
+
+struct polyval_irq_test_state {
+	struct polyval_key expected_key;
+	u8 raw_key[POLYVAL_BLOCK_SIZE];
+};
+
+static bool polyval_irq_test_func(void *state_)
+{
+	struct polyval_irq_test_state *state = state_;
+	struct polyval_key key;
+
+	polyval_preparekey(&key, state->raw_key);
+	return memcmp(&key, &state->expected_key, sizeof(key)) == 0;
+}
+
+/*
+ * Test that polyval_preparekey() produces the same output regardless of whether
+ * FPU or vector registers are usable when it is called.
+ */
+static void test_polyval_preparekey_in_irqs(struct kunit *test)
+{
+	struct polyval_irq_test_state state;
+
+	rand_bytes(state.raw_key, sizeof(state.raw_key));
+	polyval_preparekey(&state.expected_key, state.raw_key);
+	kunit_run_irq_test(test, polyval_irq_test_func, 20000, &state);
+}
+
+static int polyval_suite_init(struct kunit_suite *suite)
+{
+	u8 raw_key[POLYVAL_BLOCK_SIZE];
+
+	rand_bytes_seeded_from_len(raw_key, sizeof(raw_key));
+	polyval_preparekey(&test_key, raw_key);
+	return hash_suite_init(suite);
+}
+
+static void polyval_suite_exit(struct kunit_suite *suite)
+{
+	hash_suite_exit(suite);
+}
+
+static struct kunit_case polyval_test_cases[] = {
+	HASH_KUNIT_CASES,
+	KUNIT_CASE(test_polyval_rfc8452_testvec),
+	KUNIT_CASE(test_polyval_allones_key_and_message),
+	KUNIT_CASE(test_polyval_with_guarded_key),
+	KUNIT_CASE(test_polyval_with_minimally_aligned_key),
+	KUNIT_CASE(test_polyval_preparekey_in_irqs),
+	KUNIT_CASE(benchmark_hash),
+	{},
+};
+
+static struct kunit_suite polyval_test_suite = {
+	.name = "polyval",
+	.test_cases = polyval_test_cases,
+	.suite_init = polyval_suite_init,
+	.suite_exit = polyval_suite_exit,
+};
+kunit_test_suite(polyval_test_suite);
+
+MODULE_DESCRIPTION("KUnit tests and benchmark for POLYVAL");
+MODULE_LICENSE("GPL");

scripts/crypto/gen-hash-testvecs.py

···
 #!/usr/bin/env python3
 # SPDX-License-Identifier: GPL-2.0-or-later
 #
-# Script that generates test vectors for the given cryptographic hash function.
+# Script that generates test vectors for the given hash function.
 #
 # Copyright 2025 Google LLC
 
···
         m = (self.h + self.s) % 2**128
         return m.to_bytes(16, byteorder='little')
 
+POLYVAL_POLY = sum((1 << i) for i in [128, 127, 126, 121, 0])
+POLYVAL_BLOCK_SIZE = 16
+
+# A straightforward, unoptimized implementation of POLYVAL.
+# Reference: https://datatracker.ietf.org/doc/html/rfc8452
+class Polyval:
+    def __init__(self, key):
+        assert len(key) == 16
+        self.h = int.from_bytes(key, byteorder='little')
+        self.acc = 0
+
+    # Note: this supports partial blocks only at the end.
+    def update(self, data):
+        for i in range(0, len(data), 16):
+            # acc += block
+            self.acc ^= int.from_bytes(data[i:i+16], byteorder='little')
+            # acc = (acc * h * x^-128) mod POLYVAL_POLY
+            product = 0
+            for j in range(128):
+                if (self.h & (1 << j)) != 0:
+                    product ^= self.acc << j
+                if (product & (1 << j)) != 0:
+                    product ^= POLYVAL_POLY << j
+            self.acc = product >> 128
+        return self
+
+    def digest(self):
+        return self.acc.to_bytes(16, byteorder='little')
+
 def hash_init(alg):
     if alg == 'poly1305':
         # Use a fixed random key here, to present Poly1305 as an unkeyed hash.
         # This allows all the test cases for unkeyed hashes to work on Poly1305.
         return Poly1305(rand_bytes(POLY1305_KEY_SIZE))
+    if alg == 'polyval':
+        return Polyval(rand_bytes(POLYVAL_BLOCK_SIZE))
     return hashlib.new(alg)
 
 def hash_update(ctx, data):
···
             'poly1305_allones_macofmacs[POLY1305_DIGEST_SIZE]',
             Poly1305(key).update(data).digest())
 
+def gen_additional_polyval_testvecs():
+    key = b'\xff' * POLYVAL_BLOCK_SIZE
+    hashes = b''
+    for data_len in range(0, 4097, 16):
+        hashes += Polyval(key).update(b'\xff' * data_len).digest()
+    print_static_u8_array_definition(
+            'polyval_allones_hashofhashes[POLYVAL_DIGEST_SIZE]',
+            Polyval(key).update(hashes).digest())
+
 if len(sys.argv) != 2:
     sys.stderr.write('Usage: gen-hash-testvecs.py ALGORITHM\n')
-    sys.stderr.write('ALGORITHM may be any supported by Python hashlib, or poly1305 or sha3.\n')
+    sys.stderr.write('ALGORITHM may be any supported by Python hashlib; or poly1305, polyval, or sha3.\n')
     sys.stderr.write('Example: gen-hash-testvecs.py sha512\n')
     sys.exit(1)
 
···
 elif alg == 'poly1305':
     gen_unkeyed_testvecs(alg)
     gen_additional_poly1305_testvecs()
+elif alg == 'polyval':
+    gen_unkeyed_testvecs(alg)
+    gen_additional_polyval_testvecs()
 elif alg == 'sha3':
     print()
     print('/* SHA3-256 test vectors */')