Re: [RFC 3/3] lib: Convert test_user_copy to KUnit test

From: Vitor Massaru Iha
Date: Thu Jul 16 2020 - 12:41:00 EST

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On Wed, 2020-07-15 at 17:40 -0700, Brendan Higgins wrote:
> On Tue, Jul 14, 2020 at 8:11 PM Vitor Massaru Iha <vitor@xxxxxxxxxxx>
> 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@xxxxxxxxxxx>
> > ---
> > 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.

I didn't. Thanks I'll delete it.

> > 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@xxxxxxxxxxxx>");
> > MODULE_LICENSE("GPL");
> > --
> > 2.26.2
> >

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