usercopy: Convert test_user_copy to KUnit test

Convert the runtime tests of hardened usercopy to standard KUnit tests.

Additionally disable usercopy_test_invalid() for systems with separate
address spaces (or no MMU) since it's not sensible to test for address
confusion there (e.g. m68k).

Co-developed-by: Vitor Massaru Iha <vitor@massaru.org>
Signed-off-by: Vitor Massaru Iha <vitor@massaru.org>
Link: https://lore.kernel.org/r/20200721174654.72132-1-vitor@massaru.org
Tested-by: Ivan Orlov <ivan.orlov0322@gmail.com>
Reviewed-by: David Gow <davidgow@google.com>
Signed-off-by: Kees Cook <kees@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

Author: kees

MAINTAINERS

@@ -11962,6 +11962,7 @@ F:	arch/*/configs/hardening.config
 F:	include/linux/overflow.h
 F:	include/linux/randomize_kstack.h
 F:	kernel/configs/hardening.config
+F:	lib/usercopy_kunit.c
 F:	mm/usercopy.c
 K:	\b(add|choose)_random_kstack_offset\b
 K:	\b__check_(object_size|heap_object)\b

lib/Kconfig.debug

@@ -2505,18 +2505,6 @@ config TEST_VMALLOC
 
 	  If unsure, say N.
 
-config TEST_USER_COPY
-	tristate "Test user/kernel boundary protections"
-	depends on m
-	help
-	  This builds the "test_user_copy" module that runs sanity checks
-	  on the copy_to/from_user infrastructure, making sure basic
-	  user/kernel boundary testing is working. If it fails to load,
-	  a regression has been detected in the user/kernel memory boundary
-	  protections.
-
-	  If unsure, say N.
-
 config TEST_BPF
 	tristate "Test BPF filter functionality"
 	depends on m && NET
@@ -2814,6 +2802,15 @@ config SIPHASH_KUNIT_TEST
 	  This is intended to help people writing architecture-specific
 	  optimized versions.  If unsure, say N.
 
+config USERCOPY_KUNIT_TEST
+	tristate "KUnit Test for user/kernel boundary protections"
+	depends on KUNIT
+	default KUNIT_ALL_TESTS
+	help
+	  This builds the "usercopy_kunit" module that runs sanity checks
+	  on the copy_to/from_user infrastructure, making sure basic
+	  user/kernel boundary testing is working.
+
 config TEST_UDELAY
 	tristate "udelay test driver"
 	help

lib/Makefile

@@ -78,7 +78,6 @@ obj-$(CONFIG_TEST_LKM) += test_module.o
 obj-$(CONFIG_TEST_VMALLOC) += test_vmalloc.o
 obj-$(CONFIG_TEST_RHASHTABLE) += test_rhashtable.o
 obj-$(CONFIG_TEST_SORT) += test_sort.o
-obj-$(CONFIG_TEST_USER_COPY) += test_user_copy.o
 obj-$(CONFIG_TEST_STATIC_KEYS) += test_static_keys.o
 obj-$(CONFIG_TEST_STATIC_KEYS) += test_static_key_base.o
 obj-$(CONFIG_TEST_DYNAMIC_DEBUG) += test_dynamic_debug.o
@@ -388,6 +387,7 @@ CFLAGS_fortify_kunit.o += $(call cc-disable-warning, stringop-truncation)
 CFLAGS_fortify_kunit.o += $(DISABLE_STRUCTLEAK_PLUGIN)
 obj-$(CONFIG_FORTIFY_KUNIT_TEST) += fortify_kunit.o
 obj-$(CONFIG_SIPHASH_KUNIT_TEST) += siphash_kunit.o
+obj-$(CONFIG_USERCOPY_KUNIT_TEST) += usercopy_kunit.o
 
 obj-$(CONFIG_GENERIC_LIB_DEVMEM_IS_ALLOWED) += devmem_is_allowed.o