lib/crypto: tests: Add KUnit tests for GHASH

Add a KUnit test suite for the GHASH library functions.

It closely mirrors the POLYVAL test suite.

Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260319061723.1140720-5-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>

5 files changed, 390 insertions, 0 deletions

diff --git a/lib/crypto/.kunitconfig b/lib/crypto/.kunitconfig
index 63a592731d1d..391836511c8b 100644
--- a/lib/crypto/.kunitconfig
+++ b/lib/crypto/.kunitconfig
@@ -6,6 +6,7 @@ CONFIG_CRYPTO_LIB_AES_CBC_MACS_KUNIT_TEST=y
 CONFIG_CRYPTO_LIB_BLAKE2B_KUNIT_TEST=y
 CONFIG_CRYPTO_LIB_BLAKE2S_KUNIT_TEST=y
 CONFIG_CRYPTO_LIB_CURVE25519_KUNIT_TEST=y
+CONFIG_CRYPTO_LIB_GHASH_KUNIT_TEST=y
 CONFIG_CRYPTO_LIB_MD5_KUNIT_TEST=y
 CONFIG_CRYPTO_LIB_MLDSA_KUNIT_TEST=y
 CONFIG_CRYPTO_LIB_NH_KUNIT_TEST=y
diff --git a/lib/crypto/tests/Kconfig b/lib/crypto/tests/Kconfig
index aa627b6b9855..5b60d5c3644b 100644
--- a/lib/crypto/tests/Kconfig
+++ b/lib/crypto/tests/Kconfig
@@ -35,6 +35,14 @@ config CRYPTO_LIB_CURVE25519_KUNIT_TEST
 	help
 	  KUnit tests for the Curve25519 Diffie-Hellman function.
 
+config CRYPTO_LIB_GHASH_KUNIT_TEST
+	tristate "KUnit tests for GHASH" if !KUNIT_ALL_TESTS
+	depends on KUNIT && CRYPTO_LIB_GF128HASH
+	default KUNIT_ALL_TESTS
+	select CRYPTO_LIB_BENCHMARK_VISIBLE
+	help
+	  KUnit tests for the GHASH library functions.
+
 config CRYPTO_LIB_MD5_KUNIT_TEST
 	tristate "KUnit tests for MD5" if !KUNIT_ALL_TESTS
 	depends on KUNIT && CRYPTO_LIB_MD5
diff --git a/lib/crypto/tests/Makefile b/lib/crypto/tests/Makefile
index f864e0ffbee4..751ae507fdd0 100644
--- a/lib/crypto/tests/Makefile
+++ b/lib/crypto/tests/Makefile
@@ -4,6 +4,7 @@ obj-$(CONFIG_CRYPTO_LIB_AES_CBC_MACS_KUNIT_TEST) += aes_cbc_macs_kunit.o
 obj-$(CONFIG_CRYPTO_LIB_BLAKE2B_KUNIT_TEST) += blake2b_kunit.o
 obj-$(CONFIG_CRYPTO_LIB_BLAKE2S_KUNIT_TEST) += blake2s_kunit.o
 obj-$(CONFIG_CRYPTO_LIB_CURVE25519_KUNIT_TEST) += curve25519_kunit.o
+obj-$(CONFIG_CRYPTO_LIB_GHASH_KUNIT_TEST) += ghash_kunit.o
 obj-$(CONFIG_CRYPTO_LIB_MD5_KUNIT_TEST) += md5_kunit.o
 obj-$(CONFIG_CRYPTO_LIB_MLDSA_KUNIT_TEST) += mldsa_kunit.o
 obj-$(CONFIG_CRYPTO_LIB_NH_KUNIT_TEST) += nh_kunit.o
diff --git a/lib/crypto/tests/ghash-testvecs.h b/lib/crypto/tests/ghash-testvecs.h
new file mode 100644
index 000000000000..759eb4072336
--- /dev/null
+++ b/lib/crypto/tests/ghash-testvecs.h
@@ -0,0 +1,186 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/* This file was generated by: ./scripts/crypto/gen-hash-testvecs.py ghash */
+
+static const struct {
+	size_t data_len;
+	u8 digest[GHASH_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 = {
+			0x13, 0x91, 0xa1, 0x11, 0x08, 0xc3, 0x7e, 0xeb,
+			0x21, 0x42, 0x4a, 0xd6, 0x45, 0x0f, 0x41, 0xa7,
+		},
+	},
+	{
+		.data_len = 2,
+		.digest = {
+			0xde, 0x00, 0x63, 0x3f, 0x71, 0x0f, 0xc6, 0x29,
+			0x53, 0x2e, 0x49, 0xd9, 0xc2, 0xb7, 0x73, 0xce,
+		},
+	},
+	{
+		.data_len = 3,
+		.digest = {
+			0xcf, 0xc7, 0xa8, 0x20, 0x24, 0xe9, 0x7a, 0x6c,
+			0x2c, 0x2a, 0x34, 0x70, 0x26, 0xba, 0xd5, 0x9a,
+		},
+	},
+	{
+		.data_len = 16,
+		.digest = {
+			0xaa, 0xe0, 0xdc, 0x7f, 0xcf, 0x8b, 0xe6, 0x0c,
+			0x2e, 0x93, 0x89, 0x7d, 0x68, 0x4e, 0xc2, 0x63,
+		},
+	},
+	{
+		.data_len = 32,
+		.digest = {
+			0x4b, 0x8b, 0x93, 0x5c, 0x79, 0xad, 0x85, 0x08,
+			0xd3, 0x8a, 0xcd, 0xdd, 0x4c, 0x6e, 0x0e, 0x6f,
+		},
+	},
+	{
+		.data_len = 48,
+		.digest = {
+			0xfa, 0xa0, 0x25, 0xdd, 0x61, 0x9a, 0x52, 0x9a,
+			0xea, 0xee, 0xc6, 0x62, 0xb2, 0xba, 0x11, 0x49,
+		},
+	},
+	{
+		.data_len = 49,
+		.digest = {
+			0x23, 0xf1, 0x05, 0xeb, 0x30, 0x40, 0xb9, 0x1d,
+			0xe6, 0x35, 0x51, 0x4e, 0x0f, 0xc0, 0x1b, 0x9e,
+		},
+	},
+	{
+		.data_len = 63,
+		.digest = {
+			0x8d, 0xcf, 0xa0, 0xc8, 0x83, 0x21, 0x06, 0x81,
+			0xc6, 0x36, 0xd5, 0x62, 0xbf, 0xa0, 0xcd, 0x9c,
+		},
+	},
+	{
+		.data_len = 64,
+		.digest = {
+			0xe7, 0xca, 0xbe, 0xe7, 0x66, 0xc8, 0x85, 0xad,
+			0xbc, 0xaf, 0x58, 0x21, 0xd7, 0x67, 0x82, 0x15,
+		},
+	},
+	{
+		.data_len = 65,
+		.digest = {
+			0x9f, 0x48, 0x10, 0xd9, 0xa2, 0x6b, 0x9d, 0xe0,
+			0xb1, 0x87, 0xe1, 0x39, 0xc3, 0xd7, 0xee, 0x09,
+		},
+	},
+	{
+		.data_len = 127,
+		.digest = {
+			0xa4, 0x36, 0xb7, 0x82, 0xd2, 0x67, 0x7e, 0xaf,
+			0x5d, 0xfd, 0x67, 0x9c, 0x1d, 0x9f, 0xe4, 0xf7,
+		},
+	},
+	{
+		.data_len = 128,
+		.digest = {
+			0x57, 0xe7, 0x1d, 0x78, 0xf0, 0x8e, 0xc7, 0x0c,
+			0x15, 0xee, 0x18, 0xc4, 0xd1, 0x75, 0x90, 0xaa,
+		},
+	},
+	{
+		.data_len = 129,
+		.digest = {
+			0x9b, 0xad, 0x81, 0xa9, 0x22, 0xb2, 0x19, 0x53,
+			0x60, 0x30, 0xe7, 0xa0, 0x4f, 0xd6, 0x72, 0x42,
+		},
+	},
+	{
+		.data_len = 256,
+		.digest = {
+			0xf7, 0x33, 0x42, 0xbf, 0x58, 0xde, 0x88, 0x0f,
+			0x8d, 0x3d, 0xa6, 0x11, 0x14, 0xc3, 0xf1, 0xdc,
+		},
+	},
+	{
+		.data_len = 511,
+		.digest = {
+			0x59, 0xdc, 0xa9, 0xc0, 0x4e, 0xd6, 0x97, 0xb3,
+			0x60, 0xaf, 0xa8, 0xa0, 0xea, 0x54, 0x8e, 0xc3,
+		},
+	},
+	{
+		.data_len = 513,
+		.digest = {
+			0xa2, 0x23, 0x37, 0xcc, 0x97, 0xec, 0xea, 0xbe,
+			0xd6, 0xc7, 0x13, 0xf7, 0x93, 0x73, 0xc0, 0x64,
+		},
+	},
+	{
+		.data_len = 1000,
+		.digest = {
+			0x46, 0x8b, 0x43, 0x77, 0x9b, 0xc2, 0xfc, 0xa4,
+			0x68, 0x6a, 0x6c, 0x07, 0xa4, 0x6f, 0x47, 0x65,
+		},
+	},
+	{
+		.data_len = 3333,
+		.digest = {
+			0x69, 0x7f, 0x19, 0xc3, 0xb9, 0xa4, 0xff, 0x40,
+			0xe3, 0x03, 0x71, 0xa3, 0x88, 0x8a, 0xf1, 0xbd,
+		},
+	},
+	{
+		.data_len = 4096,
+		.digest = {
+			0x4d, 0x65, 0xe6, 0x9c, 0xeb, 0x6a, 0x46, 0x8d,
+			0xe9, 0x32, 0x96, 0x72, 0xb3, 0x0d, 0x08, 0xa9,
+		},
+	},
+	{
+		.data_len = 4128,
+		.digest = {
+			0xfc, 0xa1, 0x74, 0x46, 0x21, 0x64, 0xa7, 0x64,
+			0xbe, 0x47, 0x03, 0x1e, 0x05, 0xf7, 0xd8, 0x37,
+		},
+	},
+	{
+		.data_len = 4160,
+		.digest = {
+			0x70, 0x5b, 0xe9, 0x17, 0xab, 0xd5, 0xa2, 0xee,
+			0xcb, 0x39, 0xa4, 0x81, 0x2f, 0x41, 0x70, 0xae,
+		},
+	},
+	{
+		.data_len = 4224,
+		.digest = {
+			0x07, 0xbd, 0xb6, 0x52, 0xe2, 0x75, 0x2c, 0x33,
+			0x6d, 0x1b, 0x63, 0x56, 0x58, 0xda, 0x98, 0x55,
+		},
+	},
+	{
+		.data_len = 16384,
+		.digest = {
+			0x9c, 0xb5, 0xf4, 0x14, 0xe8, 0xa8, 0x4a, 0xde,
+			0xee, 0x7b, 0xbb, 0xd6, 0x21, 0x6d, 0x6a, 0x69,
+		},
+	},
+};
+
+static const u8 hash_testvec_consolidated[GHASH_DIGEST_SIZE] = {
+	0x08, 0xef, 0xf5, 0x27, 0xb1, 0xca, 0xd4, 0x1d,
+	0xad, 0x38, 0x69, 0x88, 0x6b, 0x16, 0xdf, 0xa8,
+};
+
+static const u8 ghash_allones_hashofhashes[GHASH_DIGEST_SIZE] = {
+	0xef, 0x85, 0x58, 0xf8, 0x54, 0x9c, 0x5e, 0x54,
+	0xd9, 0xbe, 0x04, 0x1f, 0xff, 0xff, 0xff, 0xff,
+};
diff --git a/lib/crypto/tests/ghash_kunit.c b/lib/crypto/tests/ghash_kunit.c
new file mode 100644
index 000000000000..68b3837a3607
--- /dev/null
+++ b/lib/crypto/tests/ghash_kunit.c
@@ -0,0 +1,194 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright 2026 Google LLC
+ */
+#include <crypto/gf128hash.h>
+#include "ghash-testvecs.h"
+
+/*
+ * A fixed key used when presenting GHASH 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 ghash_key test_key;
+
+static void ghash_init_withtestkey(struct ghash_ctx *ctx)
+{
+	ghash_init(ctx, &test_key);
+}
+
+static void ghash_withtestkey(const u8 *data, size_t len,
+			      u8 out[GHASH_BLOCK_SIZE])
+{
+	ghash(&test_key, data, len, out);
+}
+
+/* Generate the HASH_KUNIT_CASES using hash-test-template.h. */
+#define HASH ghash_withtestkey
+#define HASH_CTX ghash_ctx
+#define HASH_SIZE GHASH_BLOCK_SIZE
+#define HASH_INIT ghash_init_withtestkey
+#define HASH_UPDATE ghash_update
+#define HASH_FINAL ghash_final
+#include "hash-test-template.h"
+
+/*
+ * 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_ghash_allones_key_and_message(struct kunit *test)
+{
+	struct ghash_key key;
+	struct ghash_ctx hashofhashes_ctx;
+	u8 hash[GHASH_BLOCK_SIZE];
+
+	static_assert(TEST_BUF_LEN >= 4096);
+	memset(test_buf, 0xff, 4096);
+
+	ghash_preparekey(&key, test_buf);
+	ghash_init(&hashofhashes_ctx, &key);
+	for (size_t len = 0; len <= 4096; len += 16) {
+		ghash(&key, test_buf, len, hash);
+		ghash_update(&hashofhashes_ctx, hash, sizeof(hash));
+	}
+	ghash_final(&hashofhashes_ctx, hash);
+	KUNIT_ASSERT_MEMEQ(test, hash, ghash_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 ghash_key *key1,
+				  const struct ghash_key *key2)
+{
+	u8 *data = test_buf;
+	u8 hash1[GHASH_BLOCK_SIZE];
+	u8 hash2[GHASH_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);
+
+		ghash(key1, data, len, hash1);
+		ghash(key2, data, len, hash2);
+		KUNIT_ASSERT_MEMEQ(test, hash1, hash2, sizeof(hash1));
+	}
+}
+
+/* Test that no buffer overreads occur on either raw_key or ghash_key. */
+static void test_ghash_with_guarded_key(struct kunit *test)
+{
+	u8 raw_key[GHASH_BLOCK_SIZE];
+	u8 *guarded_raw_key = &test_buf[TEST_BUF_LEN - sizeof(raw_key)];
+	struct ghash_key key1, key2;
+	struct ghash_key *guarded_key =
+		(struct ghash_key *)&test_buf[TEST_BUF_LEN - sizeof(key1)];
+
+	/* Prepare with regular buffers. */
+	rand_bytes(raw_key, sizeof(raw_key));
+	ghash_preparekey(&key1, raw_key);
+
+	/* Prepare with guarded raw_key, then check that it works. */
+	memcpy(guarded_raw_key, raw_key, sizeof(raw_key));
+	ghash_preparekey(&key2, guarded_raw_key);
+	check_key_consistency(test, &key1, &key2);
+
+	/* Prepare guarded ghash_key, then check that it works. */
+	ghash_preparekey(guarded_key, raw_key);
+	check_key_consistency(test, &key1, guarded_key);
+}
+
+/*
+ * Test that ghash_key only needs to be aligned to
+ * __alignof__(struct ghash_key), i.e. 8 bytes.  The assembly code may prefer
+ * 16-byte or higher alignment, but it mustn't require it.
+ */
+static void test_ghash_with_minimally_aligned_key(struct kunit *test)
+{
+	u8 raw_key[GHASH_BLOCK_SIZE];
+	struct ghash_key key;
+	struct ghash_key *minaligned_key =
+		(struct ghash_key *)&test_buf[MAX_LEN_FOR_KEY_CHECK +
+					      __alignof__(struct ghash_key)];
+
+	KUNIT_ASSERT_TRUE(test, IS_ALIGNED((uintptr_t)minaligned_key,
+					   __alignof__(struct ghash_key)));
+	KUNIT_ASSERT_TRUE(test, !IS_ALIGNED((uintptr_t)minaligned_key,
+					    2 * __alignof__(struct ghash_key)));
+
+	rand_bytes(raw_key, sizeof(raw_key));
+	ghash_preparekey(&key, raw_key);
+	ghash_preparekey(minaligned_key, raw_key);
+	check_key_consistency(test, &key, minaligned_key);
+}
+
+struct ghash_irq_test_state {
+	struct ghash_key expected_key;
+	u8 raw_key[GHASH_BLOCK_SIZE];
+};
+
+static bool ghash_irq_test_func(void *state_)
+{
+	struct ghash_irq_test_state *state = state_;
+	struct ghash_key key;
+
+	ghash_preparekey(&key, state->raw_key);
+	return memcmp(&key, &state->expected_key, sizeof(key)) == 0;
+}
+
+/*
+ * Test that ghash_preparekey() produces the same output regardless of whether
+ * FPU or vector registers are usable when it is called.
+ */
+static void test_ghash_preparekey_in_irqs(struct kunit *test)
+{
+	struct ghash_irq_test_state state;
+
+	rand_bytes(state.raw_key, sizeof(state.raw_key));
+	ghash_preparekey(&state.expected_key, state.raw_key);
+	kunit_run_irq_test(test, ghash_irq_test_func, 200000, &state);
+}
+
+static int ghash_suite_init(struct kunit_suite *suite)
+{
+	u8 raw_key[GHASH_BLOCK_SIZE];
+
+	rand_bytes_seeded_from_len(raw_key, sizeof(raw_key));
+	ghash_preparekey(&test_key, raw_key);
+	return hash_suite_init(suite);
+}
+
+static void ghash_suite_exit(struct kunit_suite *suite)
+{
+	hash_suite_exit(suite);
+}
+
+static struct kunit_case ghash_test_cases[] = {
+	HASH_KUNIT_CASES,
+	KUNIT_CASE(test_ghash_allones_key_and_message),
+	KUNIT_CASE(test_ghash_with_guarded_key),
+	KUNIT_CASE(test_ghash_with_minimally_aligned_key),
+	KUNIT_CASE(test_ghash_preparekey_in_irqs),
+	KUNIT_CASE(benchmark_hash),
+	{},
+};
+
+static struct kunit_suite ghash_test_suite = {
+	.name = "ghash",
+	.test_cases = ghash_test_cases,
+	.suite_init = ghash_suite_init,
+	.suite_exit = ghash_suite_exit,
+};
+kunit_test_suite(ghash_test_suite);
+
+MODULE_DESCRIPTION("KUnit tests and benchmark for GHASH");
+MODULE_LICENSE("GPL");