usercopy: Convert test_user_copy to KUnit test
authorKees Cook <kees@kernel.org>
Wed, 12 Jun 2024 19:59:19 +0000 (12:59 -0700)
committerShuah Khan <skhan@linuxfoundation.org>
Sat, 15 Jun 2024 01:31:39 +0000 (19:31 -0600)
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>
MAINTAINERS
lib/Kconfig.debug
lib/Makefile
lib/test_user_copy.c [deleted file]
lib/usercopy_kunit.c [new file with mode: 0644]

index d6c90161c7bfe3886e675396cb2d2d7b44acc3b3..9a4883f7885318d3e768baebb54ccc31fa4dbc81 100644 (file)
@@ -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
index 59b6765d86b8fc6a5f8c55b6daaae545c1c14f7f..561e346f5cb051c9fb981d1903bfcb7d6c9387d7 100644 (file)
@@ -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
index 3b17690456514aac560465ec331aaed5b3dca977..fae5cc67b95a3c3cd31ea7593f8a490fa0c587d8 100644 (file)
@@ -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
 
diff --git a/lib/test_user_copy.c b/lib/test_user_copy.c
deleted file mode 100644 (file)
index 5ff04d8..0000000
+++ /dev/null
@@ -1,331 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-only
-/*
- * Kernel module for testing copy_to/from_user infrastructure.
- *
- * Copyright 2013 Google Inc. All Rights Reserved
- *
- * Authors:
- *      Kees Cook       <keescook@chromium.org>
- */
-
-#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
-
-#include <linux/mman.h>
-#include <linux/module.h>
-#include <linux/sched.h>
-#include <linux/slab.h>
-#include <linux/uaccess.h>
-#include <linux/vmalloc.h>
-
-/*
- * Several 32-bit architectures support 64-bit {get,put}_user() calls.
- * As there doesn't appear to be anything that can safely determine
- * their capability at compile-time, we just have to opt-out certain archs.
- */
-#if BITS_PER_LONG == 64 || (!(defined(CONFIG_ARM) && !defined(MMU)) && \
-                           !defined(CONFIG_M68K) &&            \
-                           !defined(CONFIG_MICROBLAZE) &&      \
-                           !defined(CONFIG_NIOS2) &&           \
-                           !defined(CONFIG_PPC32) &&           \
-                           !defined(CONFIG_SUPERH))
-# define TEST_U64
-#endif
-
-#define test(condition, msg, ...)                                      \
-({                                                                     \
-       int cond = (condition);                                         \
-       if (cond)                                                       \
-               pr_warn("[%d] " msg "\n", __LINE__, ##__VA_ARGS__);     \
-       cond;                                                           \
-})
-
-static bool is_zeroed(void *from, size_t size)
-{
-       return memchr_inv(from, 0x0, size) == NULL;
-}
-
-static int test_check_nonzero_user(char *kmem, char __user *umem, size_t size)
-{
-       int ret = 0;
-       size_t start, end, i, zero_start, zero_end;
-
-       if (test(size < 2 * PAGE_SIZE, "buffer too small"))
-               return -EINVAL;
-
-       /*
-        * We want to cross a page boundary to exercise the code more
-        * effectively. We also don't want to make the size we scan too large,
-        * otherwise the test can take a long time and cause soft lockups. So
-        * scan a 1024 byte region across the page boundary.
-        */
-       size = 1024;
-       start = PAGE_SIZE - (size / 2);
-
-       kmem += start;
-       umem += start;
-
-       zero_start = size / 4;
-       zero_end = size - zero_start;
-
-       /*
-        * We conduct a series of check_nonzero_user() tests on a block of
-        * memory with the following byte-pattern (trying every possible
-        * [start,end] pair):
-        *
-        *   [ 00 ff 00 ff ... 00 00 00 00 ... ff 00 ff 00 ]
-        *
-        * And we verify that check_nonzero_user() acts identically to
-        * memchr_inv().
-        */
-
-       memset(kmem, 0x0, size);
-       for (i = 1; i < zero_start; i += 2)
-               kmem[i] = 0xff;
-       for (i = zero_end; i < size; i += 2)
-               kmem[i] = 0xff;
-
-       ret |= test(copy_to_user(umem, kmem, size),
-                   "legitimate copy_to_user failed");
-
-       for (start = 0; start <= size; start++) {
-               for (end = start; end <= size; end++) {
-                       size_t len = end - start;
-                       int retval = check_zeroed_user(umem + start, len);
-                       int expected = is_zeroed(kmem + start, len);
-
-                       ret |= test(retval != expected,
-                                   "check_nonzero_user(=%d) != memchr_inv(=%d) mismatch (start=%zu, end=%zu)",
-                                   retval, expected, start, end);
-               }
-       }
-
-       return ret;
-}
-
-static int test_copy_struct_from_user(char *kmem, char __user *umem,
-                                     size_t size)
-{
-       int ret = 0;
-       char *umem_src = NULL, *expected = NULL;
-       size_t ksize, usize;
-
-       umem_src = kmalloc(size, GFP_KERNEL);
-       ret = test(umem_src == NULL, "kmalloc failed");
-       if (ret)
-               goto out_free;
-
-       expected = kmalloc(size, GFP_KERNEL);
-       ret = test(expected == NULL, "kmalloc failed");
-       if (ret)
-               goto out_free;
-
-       /* Fill umem with a fixed byte pattern. */
-       memset(umem_src, 0x3e, size);
-       ret |= test(copy_to_user(umem, umem_src, size),
-                   "legitimate copy_to_user failed");
-
-       /* Check basic case -- (usize == ksize). */
-       ksize = size;
-       usize = size;
-
-       memcpy(expected, umem_src, ksize);
-
-       memset(kmem, 0x0, size);
-       ret |= test(copy_struct_from_user(kmem, ksize, umem, usize),
-                   "copy_struct_from_user(usize == ksize) failed");
-       ret |= test(memcmp(kmem, expected, ksize),
-                   "copy_struct_from_user(usize == ksize) gives unexpected copy");
-
-       /* Old userspace case -- (usize < ksize). */
-       ksize = size;
-       usize = size / 2;
-
-       memcpy(expected, umem_src, usize);
-       memset(expected + usize, 0x0, ksize - usize);
-
-       memset(kmem, 0x0, size);
-       ret |= test(copy_struct_from_user(kmem, ksize, umem, usize),
-                   "copy_struct_from_user(usize < ksize) failed");
-       ret |= test(memcmp(kmem, expected, ksize),
-                   "copy_struct_from_user(usize < ksize) gives unexpected copy");
-
-       /* New userspace (-E2BIG) case -- (usize > ksize). */
-       ksize = size / 2;
-       usize = size;
-
-       memset(kmem, 0x0, size);
-       ret |= test(copy_struct_from_user(kmem, ksize, umem, usize) != -E2BIG,
-                   "copy_struct_from_user(usize > ksize) didn't give E2BIG");
-
-       /* New userspace (success) case -- (usize > ksize). */
-       ksize = size / 2;
-       usize = size;
-
-       memcpy(expected, umem_src, ksize);
-       ret |= test(clear_user(umem + ksize, usize - ksize),
-                   "legitimate clear_user failed");
-
-       memset(kmem, 0x0, size);
-       ret |= test(copy_struct_from_user(kmem, ksize, umem, usize),
-                   "copy_struct_from_user(usize > ksize) failed");
-       ret |= test(memcmp(kmem, expected, ksize),
-                   "copy_struct_from_user(usize > ksize) gives unexpected copy");
-
-out_free:
-       kfree(expected);
-       kfree(umem_src);
-       return ret;
-}
-
-static int __init test_user_copy_init(void)
-{
-       int ret = 0;
-       char *kmem;
-       char __user *usermem;
-       char *bad_usermem;
-       unsigned long user_addr;
-       u8 val_u8;
-       u16 val_u16;
-       u32 val_u32;
-#ifdef TEST_U64
-       u64 val_u64;
-#endif
-
-       kmem = kmalloc(PAGE_SIZE * 2, GFP_KERNEL);
-       if (!kmem)
-               return -ENOMEM;
-
-       user_addr = vm_mmap(NULL, 0, PAGE_SIZE * 2,
-                           PROT_READ | PROT_WRITE | PROT_EXEC,
-                           MAP_ANONYMOUS | MAP_PRIVATE, 0);
-       if (user_addr >= (unsigned long)(TASK_SIZE)) {
-               pr_warn("Failed to allocate user memory\n");
-               kfree(kmem);
-               return -ENOMEM;
-       }
-
-       usermem = (char __user *)user_addr;
-       bad_usermem = (char *)user_addr;
-
-       /*
-        * Legitimate usage: none of these copies should fail.
-        */
-       memset(kmem, 0x3a, PAGE_SIZE * 2);
-       ret |= test(copy_to_user(usermem, kmem, PAGE_SIZE),
-                   "legitimate copy_to_user failed");
-       memset(kmem, 0x0, PAGE_SIZE);
-       ret |= test(copy_from_user(kmem, usermem, PAGE_SIZE),
-                   "legitimate copy_from_user failed");
-       ret |= test(memcmp(kmem, kmem + PAGE_SIZE, PAGE_SIZE),
-                   "legitimate usercopy failed to copy data");
-
-#define test_legit(size, check)                                                  \
-       do {                                                              \
-               val_##size = check;                                       \
-               ret |= test(put_user(val_##size, (size __user *)usermem), \
-                   "legitimate put_user (" #size ") failed");            \
-               val_##size = 0;                                           \
-               ret |= test(get_user(val_##size, (size __user *)usermem), \
-                   "legitimate get_user (" #size ") failed");            \
-               ret |= test(val_##size != check,                          \
-                   "legitimate get_user (" #size ") failed to do copy"); \
-               if (val_##size != check) {                                \
-                       pr_info("0x%llx != 0x%llx\n",                     \
-                               (unsigned long long)val_##size,           \
-                               (unsigned long long)check);               \
-               }                                                         \
-       } while (0)
-
-       test_legit(u8,  0x5a);
-       test_legit(u16, 0x5a5b);
-       test_legit(u32, 0x5a5b5c5d);
-#ifdef TEST_U64
-       test_legit(u64, 0x5a5b5c5d6a6b6c6d);
-#endif
-#undef test_legit
-
-       /* Test usage of check_nonzero_user(). */
-       ret |= test_check_nonzero_user(kmem, usermem, 2 * PAGE_SIZE);
-       /* Test usage of copy_struct_from_user(). */
-       ret |= test_copy_struct_from_user(kmem, usermem, 2 * PAGE_SIZE);
-
-       /*
-        * Invalid usage: none of these copies should succeed.
-        */
-
-       /* Prepare kernel memory with check values. */
-       memset(kmem, 0x5a, PAGE_SIZE);
-       memset(kmem + PAGE_SIZE, 0, PAGE_SIZE);
-
-       /* Reject kernel-to-kernel copies through copy_from_user(). */
-       ret |= test(!copy_from_user(kmem, (char __user *)(kmem + PAGE_SIZE),
-                                   PAGE_SIZE),
-                   "illegal all-kernel copy_from_user passed");
-
-       /* Destination half of buffer should have been zeroed. */
-       ret |= test(memcmp(kmem + PAGE_SIZE, kmem, PAGE_SIZE),
-                   "zeroing failure for illegal all-kernel copy_from_user");
-
-#if 0
-       /*
-        * When running with SMAP/PAN/etc, this will Oops the kernel
-        * due to the zeroing of userspace memory on failure. This needs
-        * to be tested in LKDTM instead, since this test module does not
-        * expect to explode.
-        */
-       ret |= test(!copy_from_user(bad_usermem, (char __user *)kmem,
-                                   PAGE_SIZE),
-                   "illegal reversed copy_from_user passed");
-#endif
-       ret |= test(!copy_to_user((char __user *)kmem, kmem + PAGE_SIZE,
-                                 PAGE_SIZE),
-                   "illegal all-kernel copy_to_user passed");
-       ret |= test(!copy_to_user((char __user *)kmem, bad_usermem,
-                                 PAGE_SIZE),
-                   "illegal reversed copy_to_user passed");
-
-#define test_illegal(size, check)                                          \
-       do {                                                                \
-               val_##size = (check);                                       \
-               ret |= test(!get_user(val_##size, (size __user *)kmem),     \
-                   "illegal get_user (" #size ") passed");                 \
-               ret |= test(val_##size != (size)0,                          \
-                   "zeroing failure for illegal get_user (" #size ")");    \
-               if (val_##size != (size)0) {                                \
-                       pr_info("0x%llx != 0\n",                            \
-                               (unsigned long long)val_##size);            \
-               }                                                           \
-               ret |= test(!put_user(val_##size, (size __user *)kmem),     \
-                   "illegal put_user (" #size ") passed");                 \
-       } while (0)
-
-       test_illegal(u8,  0x5a);
-       test_illegal(u16, 0x5a5b);
-       test_illegal(u32, 0x5a5b5c5d);
-#ifdef TEST_U64
-       test_illegal(u64, 0x5a5b5c5d6a6b6c6d);
-#endif
-#undef test_illegal
-
-       vm_munmap(user_addr, PAGE_SIZE * 2);
-       kfree(kmem);
-
-       if (ret == 0) {
-               pr_info("tests passed.\n");
-               return 0;
-       }
-
-       return -EINVAL;
-}
-
-module_init(test_user_copy_init);
-
-static void __exit test_user_copy_exit(void)
-{
-       pr_info("unloaded.\n");
-}
-
-module_exit(test_user_copy_exit);
-
-MODULE_AUTHOR("Kees Cook <keescook@chromium.org>");
-MODULE_LICENSE("GPL");
diff --git a/lib/usercopy_kunit.c b/lib/usercopy_kunit.c
new file mode 100644 (file)
index 0000000..45f1e55
--- /dev/null
@@ -0,0 +1,329 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Kernel module for testing copy_to/from_user infrastructure.
+ *
+ * Copyright 2013 Google Inc. All Rights Reserved
+ *
+ * Authors:
+ *      Kees Cook       <keescook@chromium.org>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/mman.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <kunit/test.h>
+
+/*
+ * Several 32-bit architectures support 64-bit {get,put}_user() calls.
+ * As there doesn't appear to be anything that can safely determine
+ * their capability at compile-time, we just have to opt-out certain archs.
+ */
+#if BITS_PER_LONG == 64 || (!(defined(CONFIG_ARM) && !defined(MMU)) && \
+                           !defined(CONFIG_M68K) &&            \
+                           !defined(CONFIG_MICROBLAZE) &&      \
+                           !defined(CONFIG_NIOS2) &&           \
+                           !defined(CONFIG_PPC32) &&           \
+                           !defined(CONFIG_SUPERH))
+# define TEST_U64
+#endif
+
+struct usercopy_test_priv {
+       char *kmem;
+       char __user *umem;
+       size_t size;
+};
+
+static bool is_zeroed(void *from, size_t size)
+{
+       return memchr_inv(from, 0x0, size) == NULL;
+}
+
+/* Test usage of check_nonzero_user(). */
+static void usercopy_test_check_nonzero_user(struct kunit *test)
+{
+       size_t start, end, i, zero_start, zero_end;
+       struct usercopy_test_priv *priv = test->priv;
+       char __user *umem = priv->umem;
+       char *kmem = priv->kmem;
+       size_t size = priv->size;
+
+       KUNIT_ASSERT_GE_MSG(test, size, 2 * PAGE_SIZE, "buffer too small");
+
+       /*
+        * We want to cross a page boundary to exercise the code more
+        * effectively. We also don't want to make the size we scan too large,
+        * otherwise the test can take a long time and cause soft lockups. So
+        * scan a 1024 byte region across the page boundary.
+        */
+       size = 1024;
+       start = PAGE_SIZE - (size / 2);
+
+       kmem += start;
+       umem += start;
+
+       zero_start = size / 4;
+       zero_end = size - zero_start;
+
+       /*
+        * We conduct a series of check_nonzero_user() tests on a block of
+        * memory with the following byte-pattern (trying every possible
+        * [start,end] pair):
+        *
+        *   [ 00 ff 00 ff ... 00 00 00 00 ... ff 00 ff 00 ]
+        *
+        * And we verify that check_nonzero_user() acts identically to
+        * memchr_inv().
+        */
+
+       memset(kmem, 0x0, size);
+       for (i = 1; i < zero_start; i += 2)
+               kmem[i] = 0xff;
+       for (i = zero_end; i < size; i += 2)
+               kmem[i] = 0xff;
+
+       KUNIT_EXPECT_EQ_MSG(test, copy_to_user(umem, kmem, size), 0,
+               "legitimate copy_to_user failed");
+
+       for (start = 0; start <= size; start++) {
+               for (end = start; end <= size; end++) {
+                       size_t len = end - start;
+                       int retval = check_zeroed_user(umem + start, len);
+                       int expected = is_zeroed(kmem + start, len);
+
+                       KUNIT_ASSERT_EQ_MSG(test, retval, expected,
+                               "check_nonzero_user(=%d) != memchr_inv(=%d) mismatch (start=%zu, end=%zu)",
+                               retval, expected, start, end);
+               }
+       }
+}
+
+/* Test usage of copy_struct_from_user(). */
+static void usercopy_test_copy_struct_from_user(struct kunit *test)
+{
+       char *umem_src = NULL, *expected = NULL;
+       struct usercopy_test_priv *priv = test->priv;
+       char __user *umem = priv->umem;
+       char *kmem = priv->kmem;
+       size_t size = priv->size;
+       size_t ksize, usize;
+
+       umem_src = kunit_kmalloc(test, size, GFP_KERNEL);
+       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, umem_src);
+
+       expected = kunit_kmalloc(test, size, GFP_KERNEL);
+       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, expected);
+
+       /* Fill umem with a fixed byte pattern. */
+       memset(umem_src, 0x3e, size);
+       KUNIT_ASSERT_EQ_MSG(test, copy_to_user(umem, umem_src, size), 0,
+                   "legitimate copy_to_user failed");
+
+       /* Check basic case -- (usize == ksize). */
+       ksize = size;
+       usize = size;
+
+       memcpy(expected, umem_src, ksize);
+
+       memset(kmem, 0x0, size);
+       KUNIT_EXPECT_EQ_MSG(test, copy_struct_from_user(kmem, ksize, umem, usize), 0,
+                   "copy_struct_from_user(usize == ksize) failed");
+       KUNIT_EXPECT_MEMEQ_MSG(test, kmem, expected, ksize,
+                   "copy_struct_from_user(usize == ksize) gives unexpected copy");
+
+       /* Old userspace case -- (usize < ksize). */
+       ksize = size;
+       usize = size / 2;
+
+       memcpy(expected, umem_src, usize);
+       memset(expected + usize, 0x0, ksize - usize);
+
+       memset(kmem, 0x0, size);
+       KUNIT_EXPECT_EQ_MSG(test, copy_struct_from_user(kmem, ksize, umem, usize), 0,
+                   "copy_struct_from_user(usize < ksize) failed");
+       KUNIT_EXPECT_MEMEQ_MSG(test, kmem, expected, ksize,
+                   "copy_struct_from_user(usize < ksize) gives unexpected copy");
+
+       /* New userspace (-E2BIG) case -- (usize > ksize). */
+       ksize = size / 2;
+       usize = size;
+
+       memset(kmem, 0x0, size);
+       KUNIT_EXPECT_EQ_MSG(test, copy_struct_from_user(kmem, ksize, umem, usize), -E2BIG,
+                   "copy_struct_from_user(usize > ksize) didn't give E2BIG");
+
+       /* New userspace (success) case -- (usize > ksize). */
+       ksize = size / 2;
+       usize = size;
+
+       memcpy(expected, umem_src, ksize);
+       KUNIT_EXPECT_EQ_MSG(test, clear_user(umem + ksize, usize - ksize), 0,
+                   "legitimate clear_user failed");
+
+       memset(kmem, 0x0, size);
+       KUNIT_EXPECT_EQ_MSG(test, copy_struct_from_user(kmem, ksize, umem, usize), 0,
+                   "copy_struct_from_user(usize > ksize) failed");
+       KUNIT_EXPECT_MEMEQ_MSG(test, kmem, expected, ksize,
+                   "copy_struct_from_user(usize > ksize) gives unexpected copy");
+}
+
+/*
+ * Legitimate usage: none of these copies should fail.
+ */
+static void usercopy_test_valid(struct kunit *test)
+{
+       struct usercopy_test_priv *priv = test->priv;
+       char __user *usermem = priv->umem;
+       char *kmem = priv->kmem;
+
+       memset(kmem, 0x3a, PAGE_SIZE * 2);
+       KUNIT_EXPECT_EQ_MSG(test, 0, copy_to_user(usermem, kmem, PAGE_SIZE),
+            "legitimate copy_to_user failed");
+       memset(kmem, 0x0, PAGE_SIZE);
+       KUNIT_EXPECT_EQ_MSG(test, 0, copy_from_user(kmem, usermem, PAGE_SIZE),
+            "legitimate copy_from_user failed");
+       KUNIT_EXPECT_MEMEQ_MSG(test, kmem, kmem + PAGE_SIZE, PAGE_SIZE,
+            "legitimate usercopy failed to copy data");
+
+#define test_legit(size, check)                                                \
+       do {                                                            \
+               size val_##size = (check);                              \
+               KUNIT_EXPECT_EQ_MSG(test, 0,                            \
+                       put_user(val_##size, (size __user *)usermem),   \
+                       "legitimate put_user (" #size ") failed");      \
+               val_##size = 0;                                         \
+               KUNIT_EXPECT_EQ_MSG(test, 0,                            \
+                       get_user(val_##size, (size __user *)usermem),   \
+                       "legitimate get_user (" #size ") failed");      \
+               KUNIT_EXPECT_EQ_MSG(test, val_##size, check,            \
+                       "legitimate get_user (" #size ") failed to do copy"); \
+       } while (0)
+
+       test_legit(u8,  0x5a);
+       test_legit(u16, 0x5a5b);
+       test_legit(u32, 0x5a5b5c5d);
+#ifdef TEST_U64
+       test_legit(u64, 0x5a5b5c5d6a6b6c6d);
+#endif
+#undef test_legit
+}
+
+/*
+ * Invalid usage: none of these copies should succeed.
+ */
+static void usercopy_test_invalid(struct kunit *test)
+{
+       struct usercopy_test_priv *priv = test->priv;
+       char __user *usermem = priv->umem;
+       char *bad_usermem = (char *)usermem;
+       char *kmem = priv->kmem;
+       u64 *kmem_u64 = (u64 *)kmem;
+
+       if (IS_ENABLED(CONFIG_ALTERNATE_USER_ADDRESS_SPACE) ||
+           !IS_ENABLED(CONFIG_MMU)) {
+               kunit_skip(test, "Testing for kernel/userspace address confusion is only sensible on architectures with a shared address space");
+               return;
+       }
+
+       /* Prepare kernel memory with check values. */
+       memset(kmem, 0x5a, PAGE_SIZE);
+       memset(kmem + PAGE_SIZE, 0, PAGE_SIZE);
+
+       /* Reject kernel-to-kernel copies through copy_from_user(). */
+       KUNIT_EXPECT_NE_MSG(test, copy_from_user(kmem, (char __user *)(kmem + PAGE_SIZE),
+                                                PAGE_SIZE), 0,
+                   "illegal all-kernel copy_from_user passed");
+
+       /* Destination half of buffer should have been zeroed. */
+       KUNIT_EXPECT_MEMEQ_MSG(test, kmem + PAGE_SIZE, kmem, PAGE_SIZE,
+                   "zeroing failure for illegal all-kernel copy_from_user");
+
+#if 0
+       /*
+        * When running with SMAP/PAN/etc, this will Oops the kernel
+        * due to the zeroing of userspace memory on failure. This needs
+        * to be tested in LKDTM instead, since this test module does not
+        * expect to explode.
+        */
+       KUNIT_EXPECT_NE_MSG(test, copy_from_user(bad_usermem, (char __user *)kmem,
+                                                PAGE_SIZE), 0,
+                   "illegal reversed copy_from_user passed");
+#endif
+       KUNIT_EXPECT_NE_MSG(test, copy_to_user((char __user *)kmem, kmem + PAGE_SIZE,
+                                              PAGE_SIZE), 0,
+                   "illegal all-kernel copy_to_user passed");
+
+       KUNIT_EXPECT_NE_MSG(test, copy_to_user((char __user *)kmem, bad_usermem,
+                                              PAGE_SIZE), 0,
+                   "illegal reversed copy_to_user passed");
+
+#define test_illegal(size, check)                                                      \
+       do {                                                                            \
+               size val_##size = (check);                                              \
+               /* get_user() */                                                        \
+               KUNIT_EXPECT_NE_MSG(test, get_user(val_##size, (size __user *)kmem), 0, \
+                   "illegal get_user (" #size ") passed");                             \
+               KUNIT_EXPECT_EQ_MSG(test, val_##size, 0,                                \
+                   "zeroing failure for illegal get_user (" #size ")");                \
+               /* put_user() */                                                        \
+               *kmem_u64 = 0xF09FA4AFF09FA4AF;                                         \
+               KUNIT_EXPECT_NE_MSG(test, put_user(val_##size, (size __user *)kmem), 0, \
+                   "illegal put_user (" #size ") passed");                             \
+               KUNIT_EXPECT_EQ_MSG(test, *kmem_u64, 0xF09FA4AFF09FA4AF,                \
+                   "illegal put_user (" #size ") wrote to kernel memory!");            \
+       } while (0)
+
+       test_illegal(u8,  0x5a);
+       test_illegal(u16, 0x5a5b);
+       test_illegal(u32, 0x5a5b5c5d);
+#ifdef TEST_U64
+       test_illegal(u64, 0x5a5b5c5d6a6b6c6d);
+#endif
+#undef test_illegal
+}
+
+static int usercopy_test_init(struct kunit *test)
+{
+       struct usercopy_test_priv *priv;
+       unsigned long user_addr;
+
+       priv = kunit_kzalloc(test, sizeof(*priv), GFP_KERNEL);
+       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, priv);
+       test->priv = priv;
+       priv->size = PAGE_SIZE * 2;
+
+       priv->kmem = kunit_kmalloc(test, priv->size, GFP_KERNEL);
+       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, priv->kmem);
+
+       user_addr = kunit_vm_mmap(test, NULL, 0, priv->size,
+                           PROT_READ | PROT_WRITE | PROT_EXEC,
+                           MAP_ANONYMOUS | MAP_PRIVATE, 0);
+       KUNIT_ASSERT_NE_MSG(test, user_addr, 0,
+               "Could not create userspace mm");
+       KUNIT_ASSERT_LT_MSG(test, user_addr, (unsigned long)TASK_SIZE,
+               "Failed to allocate user memory");
+       priv->umem = (char __user *)user_addr;
+
+       return 0;
+}
+
+static struct kunit_case usercopy_test_cases[] = {
+       KUNIT_CASE(usercopy_test_valid),
+       KUNIT_CASE(usercopy_test_invalid),
+       KUNIT_CASE(usercopy_test_check_nonzero_user),
+       KUNIT_CASE(usercopy_test_copy_struct_from_user),
+       {}
+};
+
+static struct kunit_suite usercopy_test_suite = {
+       .name = "usercopy",
+       .init = usercopy_test_init,
+       .test_cases = usercopy_test_cases,
+};
+
+kunit_test_suites(&usercopy_test_suite);
+MODULE_AUTHOR("Kees Cook <kees@kernel.org>");
+MODULE_LICENSE("GPL");