[PATCH 04/21] nvme-auth: common: add KUnit tests for TLS key derivation

[Eric Biggers <ebiggers@kernel.org>]

Unit-test the sequence of function calls that derive tls_psk, so that we
can be more confident that changes in the implementation don't break it.

Since the NVMe specification doesn't seem to include any test vectors
for this (nor does its description of the algorithm seem to match what
was actually implemented, for that matter), I just set the expected
values to the values that the code currently produces.  In the case
of SHA-512, nvme_auth_generate_digest() currently returns -EINVAL, so
for now the test tests for that too.  If it is later determined that
some other behavior is needed, the test can be updated accordingly.

Tested with:

    tools/testing/kunit/kunit.py run --kunitconfig drivers/nvme/common/

Signed-off-by: Eric Biggers <ebiggers@kernel.org>
---
 drivers/nvme/common/.kunitconfig       |   6 +
 drivers/nvme/common/Kconfig            |   8 ++
 drivers/nvme/common/Makefile           |   2 +
 drivers/nvme/common/tests/auth_kunit.c | 175 +++++++++++++++++++++++++
 4 files changed, 191 insertions(+)
 create mode 100644 drivers/nvme/common/.kunitconfig
 create mode 100644 drivers/nvme/common/tests/auth_kunit.c

diff --git a/drivers/nvme/common/.kunitconfig b/drivers/nvme/common/.kunitconfig
new file mode 100644
index 0000000000000..60a038dc9423d
--- /dev/null
+++ b/drivers/nvme/common/.kunitconfig
@@ -0,0 +1,6 @@
+CONFIG_KUNIT=y
+CONFIG_PCI=y
+CONFIG_BLOCK=y
+CONFIG_BLK_DEV_NVME=y
+CONFIG_NVME_HOST_AUTH=y
+CONFIG_NVME_AUTH_KUNIT_TEST=y
diff --git a/drivers/nvme/common/Kconfig b/drivers/nvme/common/Kconfig
index da963e4f3f1f8..d19988c13af5f 100644
--- a/drivers/nvme/common/Kconfig
+++ b/drivers/nvme/common/Kconfig
@@ -11,5 +11,13 @@ config NVME_AUTH
 	select CRYPTO_SHA256
 	select CRYPTO_SHA512
 	select CRYPTO_DH
 	select CRYPTO_DH_RFC7919_GROUPS
 	select CRYPTO_HKDF
+
+config NVME_AUTH_KUNIT_TEST
+	tristate "KUnit tests for NVMe authentication" if !KUNIT_ALL_TESTS
+	depends on KUNIT && NVME_AUTH
+	default KUNIT_ALL_TESTS
+	help
+	  Enable KUnit tests for some of the common code for NVMe over Fabrics
+	  In-Band Authentication.
diff --git a/drivers/nvme/common/Makefile b/drivers/nvme/common/Makefile
index 681514cf2e2f5..fd9d01a609463 100644
--- a/drivers/nvme/common/Makefile
+++ b/drivers/nvme/common/Makefile
@@ -5,5 +5,7 @@ ccflags-y			+= -I$(src)
 obj-$(CONFIG_NVME_AUTH)		+= nvme-auth.o
 obj-$(CONFIG_NVME_KEYRING)	+= nvme-keyring.o
 
 nvme-auth-y			+= auth.o
 nvme-keyring-y			+= keyring.o
+
+obj-$(CONFIG_NVME_AUTH_KUNIT_TEST) += tests/auth_kunit.o
diff --git a/drivers/nvme/common/tests/auth_kunit.c b/drivers/nvme/common/tests/auth_kunit.c
new file mode 100644
index 0000000000000..28b8dd1e3b186
--- /dev/null
+++ b/drivers/nvme/common/tests/auth_kunit.c
@@ -0,0 +1,175 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Unit tests for NVMe authentication functions
+ *
+ * Copyright 2026 Google LLC
+ */
+
+#include <crypto/sha2.h>
+#include <kunit/test.h>
+#include <linux/nvme.h>
+#include <linux/nvme-auth.h>
+#include <linux/slab.h>
+
+struct nvme_auth_test_values {
+	u8 hmac_id;
+	size_t hash_len;
+	u8 expected_psk[NVME_AUTH_MAX_DIGEST_SIZE];
+	char *expected_psk_digest;
+	u8 expected_tls_psk[NVME_AUTH_MAX_DIGEST_SIZE];
+};
+
+static void kfree_action(void *ptr)
+{
+	kfree(ptr);
+}
+
+static void kunit_add_kfree_action(struct kunit *test, void *ptr)
+{
+	KUNIT_ASSERT_EQ(test, 0,
+			kunit_add_action_or_reset(test, kfree_action, ptr));
+}
+
+/*
+ * Test the derivation of a TLS PSK from the initial skey.  The vals parameter
+ * gives the expected value of tls_psk as well as the intermediate values psk
+ * and psk_digest.  The inputs are implicitly the fixed values set below.
+ */
+static void
+test_nvme_auth_derive_tls_psk(struct kunit *test,
+			      const struct nvme_auth_test_values *vals)
+{
+	const u8 hmac_id = vals->hmac_id;
+	const size_t hash_len = vals->hash_len;
+	const size_t skey_len = hash_len;
+	u8 skey[NVME_AUTH_MAX_DIGEST_SIZE];
+	u8 c1[NVME_AUTH_MAX_DIGEST_SIZE];
+	u8 c2[NVME_AUTH_MAX_DIGEST_SIZE];
+	const char *subsysnqn = "subsysnqn";
+	const char *hostnqn = "hostnqn";
+	u8 *psk = NULL, *tls_psk = NULL;
+	char *psk_digest = NULL;
+	size_t psk_len;
+	int ret;
+
+	for (int i = 0; i < NVME_AUTH_MAX_DIGEST_SIZE; i++) {
+		skey[i] = 'A' + i;
+		c1[i] = i;
+		c2[i] = 0xff - i;
+	}
+
+	ret = nvme_auth_generate_psk(hmac_id, skey, skey_len, c1, c2, hash_len,
+				     &psk, &psk_len);
+	kunit_add_kfree_action(test, psk);
+	KUNIT_ASSERT_EQ(test, 0, ret);
+	KUNIT_ASSERT_EQ(test, hash_len, psk_len);
+	KUNIT_ASSERT_MEMEQ(test, vals->expected_psk, psk, psk_len);
+
+	ret = nvme_auth_generate_digest(hmac_id, psk, psk_len, subsysnqn,
+					hostnqn, &psk_digest);
+	kunit_add_kfree_action(test, psk_digest);
+	if (vals->expected_psk_digest == NULL) {
+		/*
+		 * Algorithm has an ID assigned but is not supported by
+		 * nvme_auth_generate_digest().
+		 */
+		KUNIT_ASSERT_EQ(test, -EINVAL, ret);
+		return;
+	}
+	KUNIT_ASSERT_EQ(test, 0, ret);
+	KUNIT_ASSERT_STREQ(test, vals->expected_psk_digest, psk_digest);
+
+	ret = nvme_auth_derive_tls_psk(hmac_id, psk, psk_len, psk_digest,
+				       &tls_psk);
+	kunit_add_kfree_action(test, tls_psk);
+	KUNIT_ASSERT_EQ(test, 0, ret);
+	KUNIT_ASSERT_MEMEQ(test, vals->expected_tls_psk, tls_psk, psk_len);
+}
+
+static void test_nvme_auth_derive_tls_psk_hmac_sha256(struct kunit *test)
+{
+	static const struct nvme_auth_test_values vals = {
+		.hmac_id = NVME_AUTH_HASH_SHA256,
+		.hash_len = SHA256_DIGEST_SIZE,
+		.expected_psk = {
+			0x17, 0x33, 0xc5, 0x9f, 0xa7, 0xf4, 0x8f, 0xcf,
+			0x37, 0xf5, 0xf2, 0x6f, 0xc4, 0xff, 0x02, 0x68,
+			0xad, 0x4f, 0x78, 0xe0, 0x30, 0xf4, 0xf3, 0xb0,
+			0xbf, 0xd1, 0xd4, 0x7e, 0x7b, 0xb1, 0x44, 0x7a,
+		},
+		.expected_psk_digest = "OldoKuTfKddMuyCznAZojkWD7P4D9/AtzDzLimtOxqI=",
+		.expected_tls_psk = {
+			0x3c, 0x17, 0xda, 0x62, 0x84, 0x74, 0xa0, 0x4d,
+			0x22, 0x47, 0xc4, 0xca, 0xb4, 0x79, 0x68, 0xc9,
+			0x15, 0x38, 0x81, 0x93, 0xf7, 0xc0, 0x71, 0xbd,
+			0x94, 0x89, 0xcc, 0x36, 0x66, 0xcd, 0x7c, 0xc8,
+		},
+	};
+
+	test_nvme_auth_derive_tls_psk(test, &vals);
+}
+
+static void test_nvme_auth_derive_tls_psk_hmac_sha384(struct kunit *test)
+{
+	static const struct nvme_auth_test_values vals = {
+		.hmac_id = NVME_AUTH_HASH_SHA384,
+		.hash_len = SHA384_DIGEST_SIZE,
+		.expected_psk = {
+			0xf1, 0x4b, 0x2d, 0xd3, 0x23, 0x4c, 0x45, 0x96,
+			0x94, 0xd3, 0xbc, 0x63, 0xf8, 0x96, 0x8b, 0xd6,
+			0xb3, 0x7c, 0x2c, 0x6d, 0xe8, 0x49, 0xe2, 0x2e,
+			0x11, 0x87, 0x49, 0x00, 0x1c, 0xe4, 0xbb, 0xe8,
+			0x64, 0x0b, 0x9e, 0x3a, 0x74, 0x8c, 0xb1, 0x1c,
+			0xe4, 0xb1, 0xd7, 0x1d, 0x35, 0x9c, 0xce, 0x39,
+		},
+		.expected_psk_digest = "cffMWk8TSS7HOQebjgYEIkrPrjWPV4JE5cdPB8WhEvY4JBW5YynKyv66XscN4A9n",
+		.expected_tls_psk = {
+			0x27, 0x74, 0x75, 0x32, 0x33, 0x53, 0x7b, 0x3f,
+			0xa5, 0x0e, 0xb7, 0xd1, 0x6a, 0x8e, 0x43, 0x45,
+			0x7d, 0x85, 0xf4, 0x90, 0x6c, 0x00, 0x5b, 0x22,
+			0x36, 0x61, 0x6c, 0x5d, 0x80, 0x93, 0x9d, 0x08,
+			0x98, 0xff, 0xf1, 0x5b, 0xb8, 0xb7, 0x71, 0x19,
+			0xd2, 0xbe, 0x0a, 0xac, 0x42, 0x3e, 0x75, 0x90,
+		},
+	};
+
+	test_nvme_auth_derive_tls_psk(test, &vals);
+}
+
+static void test_nvme_auth_derive_tls_psk_hmac_sha512(struct kunit *test)
+{
+	static const struct nvme_auth_test_values vals = {
+		.hmac_id = NVME_AUTH_HASH_SHA512,
+		.hash_len = SHA512_DIGEST_SIZE,
+		.expected_psk = {
+			0x9c, 0x9f, 0x08, 0x9a, 0x61, 0x8b, 0x47, 0xd2,
+			0xd7, 0x5f, 0x4b, 0x6c, 0x28, 0x07, 0x04, 0x24,
+			0x48, 0x7b, 0x44, 0x5d, 0xd9, 0x6e, 0x70, 0xc4,
+			0xc0, 0x9b, 0x55, 0xe8, 0xb6, 0x00, 0x01, 0x52,
+			0xa3, 0x36, 0x3c, 0x34, 0x54, 0x04, 0x3f, 0x38,
+			0xf0, 0xb8, 0x50, 0x36, 0xde, 0xd4, 0x06, 0x55,
+			0x35, 0x0a, 0xa8, 0x7b, 0x8b, 0x6a, 0x28, 0x2b,
+			0x5c, 0x1a, 0xca, 0xe1, 0x62, 0x33, 0xdd, 0x5b,
+		},
+		/* nvme_auth_generate_digest() doesn't support SHA-512 yet. */
+		.expected_psk_digest = NULL,
+	};
+
+	test_nvme_auth_derive_tls_psk(test, &vals);
+}
+
+static struct kunit_case nvme_auth_test_cases[] = {
+	KUNIT_CASE(test_nvme_auth_derive_tls_psk_hmac_sha256),
+	KUNIT_CASE(test_nvme_auth_derive_tls_psk_hmac_sha384),
+	KUNIT_CASE(test_nvme_auth_derive_tls_psk_hmac_sha512),
+	{},
+};
+
+static struct kunit_suite nvme_auth_test_suite = {
+	.name = "nvme-auth",
+	.test_cases = nvme_auth_test_cases,
+};
+kunit_test_suite(nvme_auth_test_suite);
+
+MODULE_DESCRIPTION("Unit tests for NVMe authentication functions");
+MODULE_LICENSE("GPL");
-- 
2.53.0