lib/crypto: tests: Migrate ChaCha20Poly1305 self-test to KUnit

Move the ChaCha20Poly1305 test from an ad-hoc self-test to a KUnit test.

Keep the same test logic for now, just translated to KUnit.

Moving to KUnit has multiple benefits, such as:

- Consistency with the rest of the lib/crypto/ tests.

- Kernel developers familiar with KUnit, which is used kernel-wide, can
  quickly understand the test and how to enable and run it.

- The test will be automatically run by anyone using
  lib/crypto/.kunitconfig or KUnit's all_tests.config.

- Results are reported using the standard KUnit mechanism.

- It eliminates one of the few remaining back-references to crypto/ from
  lib/crypto/, specifically a reference to CONFIG_CRYPTO_SELFTESTS.

Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260327224229.137532-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>

include/crypto/chacha20poly1305.h

@@ -46,6 +46,4 @@ bool chacha20poly1305_decrypt_sg_inplace(struct scatterlist *src, size_t src_len
 					 const u64 nonce,
 					 const u8 key[at_least CHACHA20POLY1305_KEY_SIZE]);
 
-bool chacha20poly1305_selftest(void);
-
 #endif /* __CHACHA20POLY1305_H */

lib/crypto/.kunitconfig

@@ -5,6 +5,7 @@ CONFIG_CRYPTO_LIB_ENABLE_ALL_FOR_KUNIT=y
 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_CHACHA20POLY1305_KUNIT_TEST=y
 CONFIG_CRYPTO_LIB_CURVE25519_KUNIT_TEST=y
 CONFIG_CRYPTO_LIB_GHASH_KUNIT_TEST=y
 CONFIG_CRYPTO_LIB_MD5_KUNIT_TEST=y

lib/crypto/Makefile

@@ -122,7 +122,6 @@ endif # CONFIG_CRYPTO_LIB_CHACHA_ARCH
 
 obj-$(CONFIG_CRYPTO_LIB_CHACHA20POLY1305)	+= libchacha20poly1305.o
 libchacha20poly1305-y				+= chacha20poly1305.o
-libchacha20poly1305-$(CONFIG_CRYPTO_SELFTESTS)	+= chacha20poly1305-selftest.o
 
 ################################################################################
 

lib/crypto/chacha20poly1305.c

@@ -356,20 +356,6 @@ bool chacha20poly1305_decrypt_sg_inplace(struct scatterlist *src, size_t src_len
 }
 EXPORT_SYMBOL(chacha20poly1305_decrypt_sg_inplace);
 
-static int __init chacha20poly1305_init(void)
-{
-	if (IS_ENABLED(CONFIG_CRYPTO_SELFTESTS) &&
-	    WARN_ON(!chacha20poly1305_selftest()))
-		return -ENODEV;
-	return 0;
-}
-
-static void __exit chacha20poly1305_exit(void)
-{
-}
-
-module_init(chacha20poly1305_init);
-module_exit(chacha20poly1305_exit);
 MODULE_LICENSE("GPL v2");
 MODULE_DESCRIPTION("ChaCha20Poly1305 AEAD construction");
 MODULE_AUTHOR("Jason A. Donenfeld <Jason@zx2c4.com>");

lib/crypto/tests/Kconfig

@@ -27,6 +27,15 @@ config CRYPTO_LIB_BLAKE2S_KUNIT_TEST
 	help
 	  KUnit tests for the BLAKE2s cryptographic hash function.
 
+config CRYPTO_LIB_CHACHA20POLY1305_KUNIT_TEST
+	tristate "KUnit tests for ChaCha20Poly1305" if !KUNIT_ALL_TESTS
+	depends on KUNIT && CRYPTO_LIB_CHACHA20POLY1305
+	default KUNIT_ALL_TESTS
+	select CRYPTO_LIB_BENCHMARK_VISIBLE
+	help
+	  KUnit tests for the ChaCha20Poly1305 authenticated encryption
+	  algorithm.
+
 config CRYPTO_LIB_CURVE25519_KUNIT_TEST
 	tristate "KUnit tests for Curve25519" if !KUNIT_ALL_TESTS
 	depends on KUNIT && CRYPTO_LIB_CURVE25519
@@ -137,6 +146,7 @@ config CRYPTO_LIB_ENABLE_ALL_FOR_KUNIT
 	depends on KUNIT
 	select CRYPTO_LIB_AES_CBC_MACS
 	select CRYPTO_LIB_BLAKE2B
+	select CRYPTO_LIB_CHACHA20POLY1305
 	select CRYPTO_LIB_CURVE25519
 	select CRYPTO_LIB_GF128HASH
 	select CRYPTO_LIB_MD5

lib/crypto/tests/Makefile

@@ -3,6 +3,7 @@
 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_CHACHA20POLY1305_KUNIT_TEST) += chacha20poly1305_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