SUNRPC: Add KUnit tests for rpcsec_krb5.ko

The Kerberos RFCs provide test vectors to verify the operation of
an implementation. Introduce a KUnit test framework to exercise the
Linux kernel's implementation of Kerberos.

Start with test cases for the RFC 3961-defined n-fold function. The
sample vectors for that are found in RFC 3961 Section 10.

Run the GSS Kerberos 5 mechanism's unit tests with this command:

$ ./tools/testing/kunit/kunit.py run \
	--kunitconfig ./net/sunrpc/.kunitconfig
Tested-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

net/sunrpc/.kunitconfig

+CONFIG_KUNIT=y
+CONFIG_UBSAN=y
+CONFIG_STACKTRACE=y
+CONFIG_NET=y
+CONFIG_NETWORK_FILESYSTEMS=y
+CONFIG_INET=y
+CONFIG_FILE_LOCKING=y
+CONFIG_MULTIUSER=y
+CONFIG_CRYPTO=y
+CONFIG_CRYPTO_CBC=y
+CONFIG_CRYPTO_CTS=y
+CONFIG_CRYPTO_ECB=y
+CONFIG_CRYPTO_HMAC=y
+CONFIG_CRYPTO_MD5=y
+CONFIG_CRYPTO_SHA1=y
+CONFIG_CRYPTO_DES=y
+CONFIG_NFS_FS=y
+CONFIG_SUNRPC=y
+CONFIG_SUNRPC_GSS=y
+CONFIG_RPCSEC_GSS_KRB5=y
+CONFIG_RPCSEC_GSS_KRB5_ENCTYPES_DES=y
+CONFIG_RPCSEC_GSS_KRB5_KUNIT_TEST=y

net/sunrpc/Kconfig

@@ -107,6 +107,21 @@ config RPCSEC_GSS_KRB5_ENCTYPES_AES_SHA2
 	  SHA-2 digests. These include aes128-cts-hmac-sha256-128 and
 	  aes256-cts-hmac-sha384-192.
 
+config RPCSEC_GSS_KRB5_KUNIT_TEST
+	tristate "KUnit tests for RPCSEC GSS Kerberos" if !KUNIT_ALL_TESTS
+	depends on RPCSEC_GSS_KRB5 && KUNIT
+	default KUNIT_ALL_TESTS
+	help
+	  This builds the KUnit tests for RPCSEC GSS Kerberos 5.
+
+	  KUnit tests run during boot and output the results to the debug
+	  log in TAP format (https://testanything.org/). Only useful for
+	  kernel devs running KUnit test harness and are not for inclusion
+	  into a production build.
+
+	  For more information on KUnit and unit tests in general, refer
+	  to the KUnit documentation in Documentation/dev-tools/kunit/.
+
 config SUNRPC_DEBUG
 	bool "RPC: Enable dprintk debugging"
 	depends on SUNRPC && SYSCTL

net/sunrpc/auth_gss/Makefile

@@ -13,3 +13,5 @@ obj-$(CONFIG_RPCSEC_GSS_KRB5) += rpcsec_gss_krb5.o
 
 rpcsec_gss_krb5-y := gss_krb5_mech.o gss_krb5_seal.o gss_krb5_unseal.o \
 	gss_krb5_seqnum.o gss_krb5_wrap.o gss_krb5_crypto.o gss_krb5_keys.o
+
+obj-$(CONFIG_RPCSEC_GSS_KRB5_KUNIT_TEST) += gss_krb5_test.o

net/sunrpc/auth_gss/gss_krb5_internal.h

@@ -214,4 +214,8 @@ u32 krb5_etm_encrypt(struct krb5_ctx *kctx, u32 offset, struct xdr_buf *buf,
 u32 krb5_etm_decrypt(struct krb5_ctx *kctx, u32 offset, u32 len,
 		     struct xdr_buf *buf, u32 *headskip, u32 *tailskip);
 
+#if IS_ENABLED(CONFIG_KUNIT)
+void krb5_nfold(u32 inbits, const u8 *in, u32 outbits, u8 *out);
+#endif
+
 #endif /* _NET_SUNRPC_AUTH_GSS_KRB5_INTERNAL_H */

net/sunrpc/auth_gss/gss_krb5_keys.c

@@ -61,6 +61,7 @@
 #include <linux/sunrpc/xdr.h>
 #include <linux/lcm.h>
 #include <crypto/hash.h>
+#include <kunit/visibility.h>
 
 #include "gss_krb5_internal.h"
 
@@ -68,13 +69,18 @@
 # define RPCDBG_FACILITY        RPCDBG_AUTH
 #endif
 
-/*
+/**
+ * krb5_nfold - n-fold function
+ * @inbits: number of bits in @in
+ * @in: buffer containing input to fold
+ * @outbits: number of bits in the output buffer
+ * @out: buffer to hold the result
+ *
  * This is the n-fold function as described in rfc3961, sec 5.1
  * Taken from MIT Kerberos and modified.
  */
-
-static void krb5_nfold(u32 inbits, const u8 *in,
-		       u32 outbits, u8 *out)
+VISIBLE_IF_KUNIT
+void krb5_nfold(u32 inbits, const u8 *in, u32 outbits, u8 *out)
 {
 	unsigned long ulcm;
 	int byte, i, msbit;
@@ -135,6 +141,7 @@ static void krb5_nfold(u32 inbits, const u8 *in,
 		}
 	}
 }
+EXPORT_SYMBOL_IF_KUNIT(krb5_nfold);
 
 /*
  * This is the DK (derive_key) function as described in rfc3961, sec 5.1

net/sunrpc/auth_gss/gss_krb5_test.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2022 Oracle and/or its affiliates.
+ *
+ * KUnit test of SunRPC's GSS Kerberos mechanism. Subsystem
+ * name is "rpcsec_gss_krb5".
+ */
+
+#include <kunit/test.h>
+#include <kunit/visibility.h>
+
+#include <linux/kernel.h>
+
+#include <linux/sunrpc/xdr.h>
+#include <linux/sunrpc/gss_krb5.h>
+
+#include "gss_krb5_internal.h"
+
+MODULE_IMPORT_NS(EXPORTED_FOR_KUNIT_TESTING);
+
+struct gss_krb5_test_param {
+	const char			*desc;
+	u32				nfold;
+	const struct xdr_netobj         *plaintext;
+	const struct xdr_netobj		*expected_result;
+};
+
+static inline void gss_krb5_get_desc(const struct gss_krb5_test_param *param,
+				     char *desc)
+{
+	strscpy(desc, param->desc, KUNIT_PARAM_DESC_SIZE);
+}
+
+#define DEFINE_HEX_XDR_NETOBJ(name, hex_array...)		\
+	static const u8 name ## _data[] = { hex_array };	\
+	static const struct xdr_netobj name = {			\
+		.data	= (u8 *)name##_data,			\
+		.len	= sizeof(name##_data),			\
+	}
+
+/*
+ * RFC 3961 Appendix A.1.  n-fold
+ *
+ * The n-fold function is defined in section 5.1 of RFC 3961.
+ *
+ * This test material is copyright (C) The Internet Society (2005).
+ */
+
+DEFINE_HEX_XDR_NETOBJ(nfold_test1_plaintext,
+		      0x30, 0x31, 0x32, 0x33, 0x34, 0x35
+);
+DEFINE_HEX_XDR_NETOBJ(nfold_test1_expected_result,
+		      0xbe, 0x07, 0x26, 0x31, 0x27, 0x6b, 0x19, 0x55
+);
+
+DEFINE_HEX_XDR_NETOBJ(nfold_test2_plaintext,
+		      0x70, 0x61, 0x73, 0x73, 0x77, 0x6f, 0x72, 0x64
+);
+DEFINE_HEX_XDR_NETOBJ(nfold_test2_expected_result,
+		      0x78, 0xa0, 0x7b, 0x6c, 0xaf, 0x85, 0xfa
+);
+
+DEFINE_HEX_XDR_NETOBJ(nfold_test3_plaintext,
+		      0x52, 0x6f, 0x75, 0x67, 0x68, 0x20, 0x43, 0x6f,
+		      0x6e, 0x73, 0x65, 0x6e, 0x73, 0x75, 0x73, 0x2c,
+		      0x20, 0x61, 0x6e, 0x64, 0x20, 0x52, 0x75, 0x6e,
+		      0x6e, 0x69, 0x6e, 0x67, 0x20, 0x43, 0x6f, 0x64,
+		      0x65
+);
+DEFINE_HEX_XDR_NETOBJ(nfold_test3_expected_result,
+		      0xbb, 0x6e, 0xd3, 0x08, 0x70, 0xb7, 0xf0, 0xe0
+);
+
+DEFINE_HEX_XDR_NETOBJ(nfold_test4_plaintext,
+		      0x70, 0x61, 0x73, 0x73, 0x77, 0x6f, 0x72, 0x64
+);
+DEFINE_HEX_XDR_NETOBJ(nfold_test4_expected_result,
+		      0x59, 0xe4, 0xa8, 0xca, 0x7c, 0x03, 0x85, 0xc3,
+		      0xc3, 0x7b, 0x3f, 0x6d, 0x20, 0x00, 0x24, 0x7c,
+		      0xb6, 0xe6, 0xbd, 0x5b, 0x3e
+);
+
+DEFINE_HEX_XDR_NETOBJ(nfold_test5_plaintext,
+		      0x4d, 0x41, 0x53, 0x53, 0x41, 0x43, 0x48, 0x56,
+		      0x53, 0x45, 0x54, 0x54, 0x53, 0x20, 0x49, 0x4e,
+		      0x53, 0x54, 0x49, 0x54, 0x56, 0x54, 0x45, 0x20,
+		      0x4f, 0x46, 0x20, 0x54, 0x45, 0x43, 0x48, 0x4e,
+		      0x4f, 0x4c, 0x4f, 0x47, 0x59
+);
+DEFINE_HEX_XDR_NETOBJ(nfold_test5_expected_result,
+		      0xdb, 0x3b, 0x0d, 0x8f, 0x0b, 0x06, 0x1e, 0x60,
+		      0x32, 0x82, 0xb3, 0x08, 0xa5, 0x08, 0x41, 0x22,
+		      0x9a, 0xd7, 0x98, 0xfa, 0xb9, 0x54, 0x0c, 0x1b
+);
+
+DEFINE_HEX_XDR_NETOBJ(nfold_test6_plaintext,
+		      0x51
+);
+DEFINE_HEX_XDR_NETOBJ(nfold_test6_expected_result,
+		      0x51, 0x8a, 0x54, 0xa2, 0x15, 0xa8, 0x45, 0x2a,
+		      0x51, 0x8a, 0x54, 0xa2, 0x15, 0xa8, 0x45, 0x2a,
+		      0x51, 0x8a, 0x54, 0xa2, 0x15
+);
+
+DEFINE_HEX_XDR_NETOBJ(nfold_test7_plaintext,
+		      0x62, 0x61
+);
+DEFINE_HEX_XDR_NETOBJ(nfold_test7_expected_result,
+		      0xfb, 0x25, 0xd5, 0x31, 0xae, 0x89, 0x74, 0x49,
+		      0x9f, 0x52, 0xfd, 0x92, 0xea, 0x98, 0x57, 0xc4,
+		      0xba, 0x24, 0xcf, 0x29, 0x7e
+);
+
+DEFINE_HEX_XDR_NETOBJ(nfold_test_kerberos,
+		      0x6b, 0x65, 0x72, 0x62, 0x65, 0x72, 0x6f, 0x73
+);
+DEFINE_HEX_XDR_NETOBJ(nfold_test8_expected_result,
+		      0x6b, 0x65, 0x72, 0x62, 0x65, 0x72, 0x6f, 0x73
+);
+DEFINE_HEX_XDR_NETOBJ(nfold_test9_expected_result,
+		      0x6b, 0x65, 0x72, 0x62, 0x65, 0x72, 0x6f, 0x73,
+		      0x7b, 0x9b, 0x5b, 0x2b, 0x93, 0x13, 0x2b, 0x93
+);
+DEFINE_HEX_XDR_NETOBJ(nfold_test10_expected_result,
+		      0x83, 0x72, 0xc2, 0x36, 0x34, 0x4e, 0x5f, 0x15,
+		      0x50, 0xcd, 0x07, 0x47, 0xe1, 0x5d, 0x62, 0xca,
+		      0x7a, 0x5a, 0x3b, 0xce, 0xa4
+);
+DEFINE_HEX_XDR_NETOBJ(nfold_test11_expected_result,
+		      0x6b, 0x65, 0x72, 0x62, 0x65, 0x72, 0x6f, 0x73,
+		      0x7b, 0x9b, 0x5b, 0x2b, 0x93, 0x13, 0x2b, 0x93,
+		      0x5c, 0x9b, 0xdc, 0xda, 0xd9, 0x5c, 0x98, 0x99,
+		      0xc4, 0xca, 0xe4, 0xde, 0xe6, 0xd6, 0xca, 0xe4
+);
+
+static const struct gss_krb5_test_param rfc3961_nfold_test_params[] = {
+	{
+		.desc			= "64-fold(\"012345\")",
+		.nfold			= 64,
+		.plaintext		= &nfold_test1_plaintext,
+		.expected_result	= &nfold_test1_expected_result,
+	},
+	{
+		.desc			= "56-fold(\"password\")",
+		.nfold			= 56,
+		.plaintext		= &nfold_test2_plaintext,
+		.expected_result	= &nfold_test2_expected_result,
+	},
+	{
+		.desc			= "64-fold(\"Rough Consensus, and Running Code\")",
+		.nfold			= 64,
+		.plaintext		= &nfold_test3_plaintext,
+		.expected_result	= &nfold_test3_expected_result,
+	},
+	{
+		.desc			= "168-fold(\"password\")",
+		.nfold			= 168,
+		.plaintext		= &nfold_test4_plaintext,
+		.expected_result	= &nfold_test4_expected_result,
+	},
+	{
+		.desc			= "192-fold(\"MASSACHVSETTS INSTITVTE OF TECHNOLOGY\")",
+		.nfold			= 192,
+		.plaintext		= &nfold_test5_plaintext,
+		.expected_result	= &nfold_test5_expected_result,
+	},
+	{
+		.desc			= "168-fold(\"Q\")",
+		.nfold			= 168,
+		.plaintext		= &nfold_test6_plaintext,
+		.expected_result	= &nfold_test6_expected_result,
+	},
+	{
+		.desc			= "168-fold(\"ba\")",
+		.nfold			= 168,
+		.plaintext		= &nfold_test7_plaintext,
+		.expected_result	= &nfold_test7_expected_result,
+	},
+	{
+		.desc			= "64-fold(\"kerberos\")",
+		.nfold			= 64,
+		.plaintext		= &nfold_test_kerberos,
+		.expected_result	= &nfold_test8_expected_result,
+	},
+	{
+		.desc			= "128-fold(\"kerberos\")",
+		.nfold			= 128,
+		.plaintext		= &nfold_test_kerberos,
+		.expected_result	= &nfold_test9_expected_result,
+	},
+	{
+		.desc			= "168-fold(\"kerberos\")",
+		.nfold			= 168,
+		.plaintext		= &nfold_test_kerberos,
+		.expected_result	= &nfold_test10_expected_result,
+	},
+	{
+		.desc			= "256-fold(\"kerberos\")",
+		.nfold			= 256,
+		.plaintext		= &nfold_test_kerberos,
+		.expected_result	= &nfold_test11_expected_result,
+	},
+};
+
+/* Creates the function rfc3961_nfold_gen_params */
+KUNIT_ARRAY_PARAM(rfc3961_nfold, rfc3961_nfold_test_params, gss_krb5_get_desc);
+
+static void rfc3961_nfold_case(struct kunit *test)
+{
+	const struct gss_krb5_test_param *param = test->param_value;
+	u8 *result;
+
+	/* Arrange */
+	result = kunit_kzalloc(test, 4096, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, result);
+
+	/* Act */
+	krb5_nfold(param->plaintext->len * 8, param->plaintext->data,
+		   param->expected_result->len * 8, result);
+
+	/* Assert */
+	KUNIT_EXPECT_EQ_MSG(test,
+			    memcmp(param->expected_result->data,
+				   result, param->expected_result->len), 0,
+			    "result mismatch");
+}
+
+static struct kunit_case rfc3961_test_cases[] = {
+	{
+		.name			= "RFC 3961 n-fold",
+		.run_case		= rfc3961_nfold_case,
+		.generate_params	= rfc3961_nfold_gen_params,
+	},
+};
+
+static struct kunit_suite rfc3961_suite = {
+	.name			= "RFC 3961 tests",
+	.test_cases		= rfc3961_test_cases,
+};
+
+kunit_test_suites(&rfc3961_suite);
+
+MODULE_DESCRIPTION("Test RPCSEC GSS Kerberos 5 functions");
+MODULE_LICENSE("GPL");