On Tue, 11 Jun 2024 at 05:33, Kees Cook kees@kernel.org wrote:
Convert the runtime tests of hardened usercopy to standard KUnit tests.
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 Signed-off-by: Kees Cook kees@kernel.org
This looks good, particularly with the x86 fix applied.
It's still hanging on m68k -- I think at the 'illegal reversed copy_to_user passed' test -- but I'll admit to not having tried to debug it further.
One other (set of) notes below about using KUNIT_EXPECT_MEMEQ_MSG(), otherwise (assuming the m68k stuff isn't actually a regression, which I haven't tested but I imagine is unlikely),
Reviewed-by: David Gow davidgow@google.com
Thanks, -- David
MAINTAINERS | 1 + lib/Kconfig.debug | 21 +- lib/Makefile | 2 +- lib/{test_user_copy.c => usercopy_kunit.c} | 273 ++++++++++----------- 4 files changed, 142 insertions(+), 155 deletions(-) rename lib/{test_user_copy.c => usercopy_kunit.c} (47%)
diff --git a/MAINTAINERS b/MAINTAINERS index 8754ac2c259d..0cd171ec6010 100644 --- a/MAINTAINERS +++ b/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 diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 59b6765d86b8..561e346f5cb0 100644 --- a/lib/Kconfig.debug +++ 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 mhelpThis builds the "test_user_copy" module that runs sanity checkson the copy_to/from_user infrastructure, making sure basicuser/kernel boundary testing is working. If it fails to load,a regression has been detected in the user/kernel memory boundaryprotections.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 KUNITdefault KUNIT_ALL_TESTShelpThis builds the "usercopy_kunit" module that runs sanity checkson the copy_to/from_user infrastructure, making sure basicuser/kernel boundary testing is working.config TEST_UDELAY tristate "udelay test driver" help diff --git a/lib/Makefile b/lib/Makefile index 3b1769045651..fae5cc67b95a 100644 --- a/lib/Makefile +++ b/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
diff --git a/lib/test_user_copy.c b/lib/usercopy_kunit.c similarity index 47% rename from lib/test_user_copy.c rename to lib/usercopy_kunit.c index 5ff04d8fe971..f1689f2c5c7b 100644 --- a/lib/test_user_copy.c +++ b/lib/usercopy_kunit.c @@ -15,7 +15,7 @@ #include <linux/sched.h> #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 +31,27 @@ # define TEST_U64 #endif
-#define test(condition, msg, ...) \ -({ \
int cond = (condition); \if (cond) \pr_warn("[%d] " msg "\n", __LINE__, ##__VA_ARGS__); \cond; \-}) +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; }
-static int test_check_nonzero_user(char *kmem, char __user *umem, size_t size) +/* Test usage of check_nonzero_user(). */ +static void usercopy_test_check_nonzero_user(struct kunit *test) {
int ret = 0; 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;
if (test(size < 2 * PAGE_SIZE, "buffer too small"))return -EINVAL;
KUNIT_ASSERT_GE_MSG(test, size, 2 * PAGE_SIZE, "buffer too small"); /* * We want to cross a page boundary to exercise the code more@@ -84,8 +85,8 @@ 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),"legitimate copy_to_user failed");
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++) {@@ -93,35 +94,32 @@ 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_EQ_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,
size_t size)+/* Test usage of copy_struct_from_user(). */ +static void usercopy_test_copy_struct_from_user(struct kunit *test) {
int ret = 0; 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 = kmalloc(size, GFP_KERNEL);ret = test(umem_src == NULL, "kmalloc failed");if (ret)goto out_free;
umem_src = kunit_kmalloc(test, size, GFP_KERNEL);KUNIT_ASSERT_NOT_ERR_OR_NULL(test, umem_src);
expected = kmalloc(size, GFP_KERNEL);ret = test(expected == NULL, "kmalloc failed");if (ret)goto out_free;
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);
ret |= test(copy_to_user(umem, umem_src, size),
KUNIT_ASSERT_EQ_MSG(test, copy_to_user(umem, umem_src, size), 0, "legitimate copy_to_user failed"); /* Check basic case -- (usize == ksize). */@@ -131,9 +129,9 @@ 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_EQ_MSG(test, copy_struct_from_user(kmem, ksize, umem, usize), 0, "copy_struct_from_user(usize == ksize) failed");
ret |= test(memcmp(kmem, expected, ksize),
KUNIT_EXPECT_EQ_MSG(test, memcmp(kmem, expected, ksize), 0, "copy_struct_from_user(usize == ksize) gives unexpected copy");
Should we use KUNIT_EXPECT_MEMEQ_MSG() here, rather than memcmp()? That'll print a nice hexdump of the difference.
/* Old userspace case -- (usize < ksize). */@@ -144,9 +142,9 @@ 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_EQ_MSG(test, copy_struct_from_user(kmem, ksize, umem, usize), 0, "copy_struct_from_user(usize < ksize) failed");
ret |= test(memcmp(kmem, expected, ksize),
KUNIT_EXPECT_EQ_MSG(test, memcmp(kmem, expected, ksize), 0, "copy_struct_from_user(usize < ksize) gives unexpected copy");
Again, can we use KUNIT_EXPECT_MEMEQ_MSG() here, rather than memcmp()?
/* New userspace (-E2BIG) case -- (usize > ksize). */@@ -154,7 +152,7 @@ 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_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). */@@ -162,78 +160,46 @@ 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_EQ_MSG(test, clear_user(umem + ksize, usize - ksize), 0, "legitimate clear_user failed"); memset(kmem, 0x0, size);
ret |= test(copy_struct_from_user(kmem, ksize, umem, usize),
KUNIT_EXPECT_EQ_MSG(test, copy_struct_from_user(kmem, ksize, umem, usize), 0, "copy_struct_from_user(usize > ksize) failed");
ret |= test(memcmp(kmem, expected, ksize),
KUNIT_EXPECT_EQ_MSG(test, memcmp(kmem, expected, ksize), 0, "copy_struct_from_user(usize > ksize) gives unexpected copy");
Another place to use KUNIT_EXPECT_MEMEQ_MSG()?
-out_free:
kfree(expected);kfree(umem_src);return ret;}
-static int __init test_user_copy_init(void) +/*
- Legitimate usage: none of these copies should fail.
- */
+static void usercopy_test_valid(struct kunit *test) {
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;
struct usercopy_test_priv *priv = test->priv;char __user *usermem = priv->umem;char *kmem = priv->kmem;
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");
KUNIT_EXPECT_EQ_MSG(test, 0, 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_EQ_MSG(test, 0, copy_from_user(kmem, usermem, PAGE_SIZE),"legitimate copy_from_user failed");KUNIT_EXPECT_EQ_MSG(test, 0, memcmp(kmem, kmem + PAGE_SIZE, PAGE_SIZE),"legitimate usercopy failed to copy data");
KUNIT_EXPECT_MEMEQ_MSG()?
+#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);@@ -243,27 +209,30 @@ static int __init test_user_copy_init(void) 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.*/+/*
- 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; /* 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),
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. */
ret |= test(memcmp(kmem + PAGE_SIZE, kmem, PAGE_SIZE),
KUNIT_EXPECT_EQ_MSG(test, memcmp(kmem + PAGE_SIZE, kmem, PAGE_SIZE), 0, "zeroing failure for illegal all-kernel copy_from_user");
KUNIT_EXPECT_MEMEQ_MSG()?
#if 0 @@ -273,30 +242,31 @@ 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),
KUNIT_EXPECT_NE_MSG(test, copy_from_user(bad_usermem, (char __user *)kmem,PAGE_SIZE), 0, "illegal reversed copy_from_user passed");#endif
ret |= test(!copy_to_user((char __user *)kmem, kmem + PAGE_SIZE,PAGE_SIZE),
KUNIT_EXPECT_NE_MSG(test, copy_to_user((char __user *)kmem, kmem + PAGE_SIZE,PAGE_SIZE), 0, "illegal all-kernel copy_to_user passed");
ret |= test(!copy_to_user((char __user *)kmem, bad_usermem,PAGE_SIZE),
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 { \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"); \+#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);@@ -306,26 +276,45 @@ static int __init test_user_copy_init(void) test_illegal(u64, 0x5a5b5c5d6a6b6c6d); #endif #undef test_illegal +}
vm_munmap(user_addr, PAGE_SIZE * 2);kfree(kmem);+static int usercopy_test_init(struct kunit *test) +{
struct usercopy_test_priv *priv;unsigned long user_addr;
if (ret == 0) {pr_info("tests passed.\n");return 0;}
priv = kunit_kzalloc(test, sizeof(*priv), GFP_KERNEL);KUNIT_ASSERT_NOT_ERR_OR_NULL(test, priv);test->priv = priv;priv->size = PAGE_SIZE * 2;
return -EINVAL;-}
priv->kmem = kunit_kmalloc(test, priv->size, GFP_KERNEL);KUNIT_ASSERT_NOT_ERR_OR_NULL(test, priv->kmem);-module_init(test_user_copy_init);
user_addr = kunit_vm_mmap(test, NULL, 0, priv->size,PROT_READ | PROT_WRITE | PROT_EXEC,MAP_ANONYMOUS | MAP_PRIVATE, 0);KUNIT_ASSERT_LT_MSG(test, user_addr, (unsigned long)TASK_SIZE,"Failed to allocate user memory");priv->umem = (char __user *)user_addr;-static void __exit test_user_copy_exit(void) -{
pr_info("unloaded.\n");
return 0;}
-module_exit(test_user_copy_exit);
-MODULE_AUTHOR("Kees Cook keescook@chromium.org"); +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"); -- 2.34.1