[Linux-kernel-mentees] [RFC 3/3] lib: Convert test_user_copy to KUnit test

Brendan Higgins brendanhiggins at google.com
Thu Jul 16 00:40:35 UTC 2020


On Tue, Jul 14, 2020 at 8:11 PM Vitor Massaru Iha <vitor at massaru.org> wrote:
>
> This adds the conversion of the runtime tests of test_user_copy fuctions,
> from `lib/test_user_copy.c`to KUnit tests.
>
> Signed-off-by: Vitor Massaru Iha <vitor at massaru.org>
> ---
>  lib/Kconfig.debug                           |  17 ++
>  lib/Makefile                                |   2 +-
>  lib/{test_user_copy.c => user_copy_kunit.c} | 196 +++++++++-----------
>  3 files changed, 102 insertions(+), 113 deletions(-)
>  rename lib/{test_user_copy.c => user_copy_kunit.c} (55%)
>
> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> index 9ad9210d70a1..29558674c011 100644
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -2154,6 +2154,23 @@ config SYSCTL_KUNIT_TEST
>
>           If unsure, say N.
>
> +config USER_COPY_KUNIT
> +       tristate "KUnit Test for user/kernel boundary protections"
> +       depends on KUNIT
> +       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.
> +
> +          For more information on KUnit and unit tests in general please refer
> +         to the KUnit documentation in Documentation/dev-tools/kunit/.
> +
> +         If unsure, say N.

Where do you delete the entry for CONFIG_TEST_USER_COPY? I don't see it here.

>  config LIST_KUNIT_TEST
>         tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS
>         depends on KUNIT
> diff --git a/lib/Makefile b/lib/Makefile
> index b1c42c10073b..8c145f85accc 100644
> --- a/lib/Makefile
> +++ b/lib/Makefile
> @@ -78,7 +78,6 @@ obj-$(CONFIG_TEST_VMALLOC) += test_vmalloc.o
>  obj-$(CONFIG_TEST_OVERFLOW) += test_overflow.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_PRINTF) += test_printf.o
> @@ -318,3 +317,4 @@ obj-$(CONFIG_OBJAGG) += objagg.o
>  # KUnit tests
>  obj-$(CONFIG_LIST_KUNIT_TEST) += list-test.o
>  obj-$(CONFIG_LINEAR_RANGES_TEST) += test_linear_ranges.o
> +obj-$(CONFIG_USER_COPY_KUNIT) += user_copy_kunit.o
> diff --git a/lib/test_user_copy.c b/lib/user_copy_kunit.c
> similarity index 55%
> rename from lib/test_user_copy.c
> rename to lib/user_copy_kunit.c
> index 5ff04d8fe971..c15bb1e997d6 100644
> --- a/lib/test_user_copy.c
> +++ b/lib/user_copy_kunit.c
> @@ -16,6 +16,7 @@
>  #include <linux/slab.h>
>  #include <linux/uaccess.h>
>  #include <linux/vmalloc.h>
> +#include <kunit/test.h>
>
>  /*
>   * Several 32-bit architectures support 64-bit {get,put}_user() calls.
> @@ -31,26 +32,16 @@
>  # 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)
> +static void test_check_nonzero_user(struct kunit *test, 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;
> +       KUNIT_EXPECT_FALSE_MSG(test, size < 2 * PAGE_SIZE, "buffer too small");
>
>         /*
>          * We want to cross a page boundary to exercise the code more
> @@ -84,7 +75,7 @@ static int test_check_nonzero_user(char *kmem, char __user *umem, size_t size)
>         for (i = zero_end; i < size; i += 2)
>                 kmem[i] = 0xff;
>
> -       ret |= test(copy_to_user(umem, kmem, size),
> +       KUNIT_EXPECT_FALSE_MSG(test, copy_to_user(umem, kmem, size),
>                     "legitimate copy_to_user failed");
>
>         for (start = 0; start <= size; start++) {
> @@ -93,35 +84,31 @@ static int test_check_nonzero_user(char *kmem, char __user *umem, size_t size)
>                         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);
> +                       KUNIT_EXPECT_FALSE_MSG(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,
> +static void test_copy_struct_from_user(struct kunit *test, 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;
> +       KUNIT_EXPECT_FALSE_MSG(test, umem_src == NULL, "kmalloc failed");
>
>         expected = kmalloc(size, GFP_KERNEL);
> -       ret = test(expected == NULL, "kmalloc failed");
> -       if (ret)
> -               goto out_free;
> +
> +       if (expected == NULL)
> +               kfree(umem_src);
> +       KUNIT_EXPECT_FALSE_MSG(test, expected == NULL, "kmalloc failed");
>
>         /* Fill umem with a fixed byte pattern. */
>         memset(umem_src, 0x3e, size);
> -       ret |= test(copy_to_user(umem, umem_src, size),
> +       KUNIT_EXPECT_FALSE_MSG(test, copy_to_user(umem, umem_src, size),
>                     "legitimate copy_to_user failed");
>
>         /* Check basic case -- (usize == ksize). */
> @@ -131,9 +118,9 @@ static int test_copy_struct_from_user(char *kmem, char __user *umem,
>         memcpy(expected, umem_src, ksize);
>
>         memset(kmem, 0x0, size);
> -       ret |= test(copy_struct_from_user(kmem, ksize, umem, usize),
> +       KUNIT_EXPECT_FALSE_MSG(test, copy_struct_from_user(kmem, ksize, umem, usize),
>                     "copy_struct_from_user(usize == ksize) failed");
> -       ret |= test(memcmp(kmem, expected, ksize),
> +       KUNIT_EXPECT_FALSE_MSG(test, memcmp(kmem, expected, ksize),
>                     "copy_struct_from_user(usize == ksize) gives unexpected copy");
>
>         /* Old userspace case -- (usize < ksize). */
> @@ -144,9 +131,9 @@ static int test_copy_struct_from_user(char *kmem, char __user *umem,
>         memset(expected + usize, 0x0, ksize - usize);
>
>         memset(kmem, 0x0, size);
> -       ret |= test(copy_struct_from_user(kmem, ksize, umem, usize),
> +       KUNIT_EXPECT_FALSE_MSG(test, copy_struct_from_user(kmem, ksize, umem, usize),
>                     "copy_struct_from_user(usize < ksize) failed");
> -       ret |= test(memcmp(kmem, expected, ksize),
> +       KUNIT_EXPECT_FALSE_MSG(test, memcmp(kmem, expected, ksize),
>                     "copy_struct_from_user(usize < ksize) gives unexpected copy");
>
>         /* New userspace (-E2BIG) case -- (usize > ksize). */
> @@ -154,7 +141,7 @@ static int test_copy_struct_from_user(char *kmem, char __user *umem,
>         usize = size;
>
>         memset(kmem, 0x0, size);
> -       ret |= test(copy_struct_from_user(kmem, ksize, umem, usize) != -E2BIG,
> +       KUNIT_EXPECT_FALSE_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). */
> @@ -162,24 +149,18 @@ static int test_copy_struct_from_user(char *kmem, char __user *umem,
>         usize = size;
>
>         memcpy(expected, umem_src, ksize);
> -       ret |= test(clear_user(umem + ksize, usize - ksize),
> +       KUNIT_EXPECT_FALSE_MSG(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),
> +       KUNIT_EXPECT_FALSE_MSG(test, copy_struct_from_user(kmem, ksize, umem, usize),
>                     "copy_struct_from_user(usize > ksize) failed");
> -       ret |= test(memcmp(kmem, expected, ksize),
> +       KUNIT_EXPECT_FALSE_MSG(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)
> +static void user_copy_test(struct kunit *test)
>  {
> -       int ret = 0;
>         char *kmem;
>         char __user *usermem;
>         char *bad_usermem;
> @@ -192,16 +173,14 @@ static int __init test_user_copy_init(void)
>  #endif
>
>         kmem = kmalloc(PAGE_SIZE * 2, GFP_KERNEL);
> -       if (!kmem)
> -               return -ENOMEM;
> +       KUNIT_EXPECT_FALSE_MSG(test, kmem == NULL, "kmalloc failed");
>
>         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;
> +               KUNIT_FAIL(test, "Failed to allocate user memory");
>         }
>
>         usermem = (char __user *)user_addr;
> @@ -211,29 +190,29 @@ static int __init test_user_copy_init(void)
>          * 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");
> +       KUNIT_EXPECT_FALSE_MSG(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);               \
> -               }                                                         \
> +       KUNIT_EXPECT_FALSE_MSG(test, copy_from_user(kmem, usermem, PAGE_SIZE),
> +                              "legitimate copy_from_user failed");
> +       KUNIT_EXPECT_FALSE_MSG(test, memcmp(kmem, kmem + PAGE_SIZE, PAGE_SIZE),
> +                              "legitimate usercopy failed to copy data");
> +
> +#define test_legit(size, check)                                                                        \
> +       do {                                                                                    \
> +               val_##size = check;                                                             \
> +               KUNIT_EXPECT_FALSE_MSG(test, put_user(val_##size, (size __user *)usermem),      \
> +                               "legitimate put_user (" #size ") failed");                      \
> +               val_##size = 0;                                                                 \
> +               KUNIT_EXPECT_FALSE_MSG(test, get_user(val_##size, (size __user *)usermem),      \
> +                               "legitimate get_user (" #size ") failed");                      \
> +               KUNIT_EXPECT_FALSE_MSG(test, val_##size != check,                               \
> +                               "legitimate get_user (" #size ") failed to do copy");           \
> +               if (val_##size != check) {                                                      \
> +                       kunit_info(test, "0x%llx != 0x%llx\n",                                  \
> +                               (unsigned long long)val_##size,                                 \
> +                               (unsigned long long)check);                                     \
> +               }                                                                               \
>         } while (0)
>
>         test_legit(u8,  0x5a);
> @@ -245,9 +224,9 @@ static int __init test_user_copy_init(void)
>  #undef test_legit
>
>         /* Test usage of check_nonzero_user(). */
> -       ret |= test_check_nonzero_user(kmem, usermem, 2 * PAGE_SIZE);
> +       test_check_nonzero_user(test, kmem, usermem, 2 * PAGE_SIZE);
>         /* Test usage of copy_struct_from_user(). */
> -       ret |= test_copy_struct_from_user(kmem, usermem, 2 * PAGE_SIZE);
> +       test_copy_struct_from_user(test, kmem, usermem, 2 * PAGE_SIZE);
>
>         /*
>          * Invalid usage: none of these copies should succeed.
> @@ -258,13 +237,13 @@ static int __init test_user_copy_init(void)
>         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");
> +       KUNIT_EXPECT_FALSE_MSG(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");
> +       KUNIT_EXPECT_FALSE_MSG(test, memcmp(kmem + PAGE_SIZE, kmem, PAGE_SIZE),
> +                       "zeroing failure for illegal all-kernel copy_from_user");
>
>  #if 0
>         /*
> @@ -273,30 +252,28 @@ static int __init test_user_copy_init(void)
>          * 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");
> +       KUNIT_EXPECT_FALSE_MSG(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");                 \
> +       KUNIT_EXPECT_FALSE_MSG(test, !copy_to_user((char __user *)kmem, kmem + PAGE_SIZE, PAGE_SIZE),
> +                       "illegal all-kernel copy_to_user passed");
> +       KUNIT_EXPECT_FALSE_MSG(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);                                                           \
> +               KUNIT_EXPECT_FALSE_MSG(test, !get_user(val_##size, (size __user *)kmem),        \
> +                               "illegal get_user (" #size ") passed");                         \
> +               KUNIT_EXPECT_FALSE_MSG(test, val_##size != (size)0,                             \
> +                               "zeroing failure for illegal get_user (" #size ")");            \
> +               if (val_##size != (size)0) {                                                    \
> +                       kunit_info(test, "0x%llx != 0\n",                                       \
> +                                       (unsigned long long)val_##size);                        \
> +               }                                                                               \
> +               KUNIT_EXPECT_FALSE_MSG(test, !put_user(val_##size, (size __user *)kmem),        \
> +                               "illegal put_user (" #size ") passed");                         \
>         } while (0)
>
>         test_illegal(u8,  0x5a);
> @@ -309,23 +286,18 @@ static int __init test_user_copy_init(void)
>
>         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");
> -}
> +static struct kunit_case user_copy_test_cases[] = {
> +       KUNIT_CASE(user_copy_test),
> +       {}
> +};
>
> -module_exit(test_user_copy_exit);
> +static struct kunit_suite user_copy_test_suite = {
> +       .name = "user_copy",
> +       .test_cases = user_copy_test_cases,
> +};
>
> +kunit_test_suites(&user_copy_test_suite);
>  MODULE_AUTHOR("Kees Cook <keescook at chromium.org>");
>  MODULE_LICENSE("GPL");
> --
> 2.26.2
>


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