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Date: Wed, 15 Jul 2020 17:40:35 -0700
From: Brendan Higgins <brendanhiggins@...gle.com>
To: Vitor Massaru Iha <vitor@...saru.org>
Cc: KUnit Development <kunit-dev@...glegroups.com>,
"open list:KERNEL SELFTEST FRAMEWORK"
<linux-kselftest@...r.kernel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Kees Cook <keescook@...omium.org>,
David Gow <davidgow@...gle.com>,
Shuah Khan <skhan@...uxfoundation.org>,
linux-kernel-mentees@...ts.linuxfoundation.org
Subject: Re: [RFC 3/3] lib: Convert test_user_copy to KUnit test
On Tue, Jul 14, 2020 at 8:11 PM Vitor Massaru Iha <vitor@...saru.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@...saru.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@...omium.org>");
> MODULE_LICENSE("GPL");
> --
> 2.26.2
>
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