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-rw-r--r--lib/crypto/tests/poly1305_kunit.c165
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diff --git a/lib/crypto/tests/poly1305_kunit.c b/lib/crypto/tests/poly1305_kunit.c
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+++ b/lib/crypto/tests/poly1305_kunit.c
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+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright 2025 Google LLC
+ */
+#include <crypto/poly1305.h>
+#include "poly1305-testvecs.h"
+
+/*
+ * A fixed key used when presenting Poly1305 as an unkeyed hash function in
+ * order to reuse hash-test-template.h. At the beginning of the test suite,
+ * this is initialized to bytes generated from a fixed seed.
+ */
+static u8 test_key[POLY1305_KEY_SIZE];
+
+/* This probably should be in the actual API, but just define it here for now */
+static void poly1305(const u8 key[POLY1305_KEY_SIZE], const u8 *data,
+ size_t len, u8 out[POLY1305_DIGEST_SIZE])
+{
+ struct poly1305_desc_ctx ctx;
+
+ poly1305_init(&ctx, key);
+ poly1305_update(&ctx, data, len);
+ poly1305_final(&ctx, out);
+}
+
+static void poly1305_init_withtestkey(struct poly1305_desc_ctx *ctx)
+{
+ poly1305_init(ctx, test_key);
+}
+
+static void poly1305_withtestkey(const u8 *data, size_t len,
+ u8 out[POLY1305_DIGEST_SIZE])
+{
+ poly1305(test_key, data, len, out);
+}
+
+/* Generate the HASH_KUNIT_CASES using hash-test-template.h. */
+#define HASH poly1305_withtestkey
+#define HASH_CTX poly1305_desc_ctx
+#define HASH_SIZE POLY1305_DIGEST_SIZE
+#define HASH_INIT poly1305_init_withtestkey
+#define HASH_UPDATE poly1305_update
+#define HASH_FINAL poly1305_final
+#include "hash-test-template.h"
+
+static int poly1305_suite_init(struct kunit_suite *suite)
+{
+ rand_bytes_seeded_from_len(test_key, POLY1305_KEY_SIZE);
+ return hash_suite_init(suite);
+}
+
+static void poly1305_suite_exit(struct kunit_suite *suite)
+{
+ hash_suite_exit(suite);
+}
+
+/*
+ * Poly1305 test case which uses a key and message consisting only of one bits:
+ *
+ * - Using an all-one-bits r_key tests the key clamping.
+ * - Using an all-one-bits s_key tests carries in implementations of the
+ * addition mod 2**128 during finalization.
+ * - Using all-one-bits message, and to a lesser extent r_key, tends to maximize
+ * any intermediate accumulator values. This increases the chance of
+ * detecting bugs that occur only in rare cases where the accumulator values
+ * get very large, for example the bug fixed by commit 678cce4019d746da
+ * ("crypto: x86/poly1305 - fix overflow during partial reduction").
+ *
+ * Accumulator overflow bugs may be specific to particular update lengths (in
+ * blocks) and/or particular values of the previous acculumator. Note that the
+ * accumulator starts at 0 which gives the lowest chance of an overflow. Thus,
+ * a single all-one-bits test vector may be insufficient.
+ *
+ * Considering that, do the following test: continuously update a single
+ * Poly1305 context with all-one-bits data of varying lengths (0, 16, 32, ...,
+ * 4096 bytes). After each update, generate the MAC from the current context,
+ * and feed that MAC into a separate Poly1305 context. Repeat that entire
+ * sequence of updates 32 times without re-initializing either context,
+ * resulting in a total of 8224 MAC computations from a long-running, cumulative
+ * context. Finally, generate and verify the MAC of all the MACs.
+ */
+static void test_poly1305_allones_keys_and_message(struct kunit *test)
+{
+ struct poly1305_desc_ctx mac_ctx, macofmacs_ctx;
+ u8 mac[POLY1305_DIGEST_SIZE];
+
+ static_assert(TEST_BUF_LEN >= 4096);
+ memset(test_buf, 0xff, 4096);
+
+ poly1305_init(&mac_ctx, test_buf);
+ poly1305_init(&macofmacs_ctx, test_buf);
+ for (int i = 0; i < 32; i++) {
+ for (size_t len = 0; len <= 4096; len += 16) {
+ struct poly1305_desc_ctx tmp_ctx;
+
+ poly1305_update(&mac_ctx, test_buf, len);
+ tmp_ctx = mac_ctx;
+ poly1305_final(&tmp_ctx, mac);
+ poly1305_update(&macofmacs_ctx, mac,
+ POLY1305_DIGEST_SIZE);
+ }
+ }
+ poly1305_final(&macofmacs_ctx, mac);
+ KUNIT_ASSERT_MEMEQ(test, mac, poly1305_allones_macofmacs,
+ POLY1305_DIGEST_SIZE);
+}
+
+/*
+ * Poly1305 test case which uses r_key=1, s_key=0, and a 48-byte message
+ * consisting of three blocks with integer values [2**128 - i, 0, 0]. In this
+ * case, the result of the polynomial evaluation is 2**130 - i. For small
+ * values of i, this is very close to the modulus 2**130 - 5, which helps catch
+ * edge case bugs in the modular reduction logic.
+ */
+static void test_poly1305_reduction_edge_cases(struct kunit *test)
+{
+ static const u8 key[POLY1305_KEY_SIZE] = { 1 }; /* r_key=1, s_key=0 */
+ u8 data[3 * POLY1305_BLOCK_SIZE] = {};
+ u8 expected_mac[POLY1305_DIGEST_SIZE];
+ u8 actual_mac[POLY1305_DIGEST_SIZE];
+
+ for (int i = 1; i <= 10; i++) {
+ /* Set the first data block to 2**128 - i. */
+ data[0] = -i;
+ memset(&data[1], 0xff, POLY1305_BLOCK_SIZE - 1);
+
+ /*
+ * Assuming s_key=0, the expected MAC as an integer is
+ * (2**130 - i mod 2**130 - 5) + 0 mod 2**128. If 1 <= i <= 5,
+ * that's 5 - i. If 6 <= i <= 10, that's 2**128 - i.
+ */
+ if (i <= 5) {
+ expected_mac[0] = 5 - i;
+ memset(&expected_mac[1], 0, POLY1305_DIGEST_SIZE - 1);
+ } else {
+ expected_mac[0] = -i;
+ memset(&expected_mac[1], 0xff,
+ POLY1305_DIGEST_SIZE - 1);
+ }
+
+ /* Compute and verify the MAC. */
+ poly1305(key, data, sizeof(data), actual_mac);
+ KUNIT_ASSERT_MEMEQ(test, actual_mac, expected_mac,
+ POLY1305_DIGEST_SIZE);
+ }
+}
+
+static struct kunit_case poly1305_test_cases[] = {
+ HASH_KUNIT_CASES,
+ KUNIT_CASE(test_poly1305_allones_keys_and_message),
+ KUNIT_CASE(test_poly1305_reduction_edge_cases),
+ KUNIT_CASE(benchmark_hash),
+ {},
+};
+
+static struct kunit_suite poly1305_test_suite = {
+ .name = "poly1305",
+ .test_cases = poly1305_test_cases,
+ .suite_init = poly1305_suite_init,
+ .suite_exit = poly1305_suite_exit,
+};
+kunit_test_suite(poly1305_test_suite);
+
+MODULE_DESCRIPTION("KUnit tests and benchmark for Poly1305");
+MODULE_LICENSE("GPL");