[PATCH v2 2/2] usercopy: Convert test_user_copy to KUnit test

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 --- 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 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 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");

/* 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");

/* 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"); - -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"); + +#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");

#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");