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Diffstat (limited to 'lib/usercopy_kunit.c')
| -rw-r--r-- | lib/usercopy_kunit.c | 335 |
1 files changed, 335 insertions, 0 deletions
diff --git a/lib/usercopy_kunit.c b/lib/usercopy_kunit.c new file mode 100644 index 000000000000..77fa00a13df7 --- /dev/null +++ b/lib/usercopy_kunit.c @@ -0,0 +1,335 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Kernel module for testing copy_to/from_user infrastructure. + * + * Copyright 2013 Google Inc. All Rights Reserved + * + * Authors: + * Kees Cook <keescook@chromium.org> + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/mman.h> +#include <linux/module.h> +#include <linux/sched.h> +#include <linux/slab.h> +#include <linux/uaccess.h> +#include <kunit/test.h> + +/* + * Several 32-bit architectures support 64-bit {get,put}_user() calls. + * As there doesn't appear to be anything that can safely determine + * their capability at compile-time, we just have to opt-out certain archs. + */ +#if BITS_PER_LONG == 64 || (!(defined(CONFIG_ARM) && !defined(MMU)) && \ + !defined(CONFIG_M68K) && \ + !defined(CONFIG_MICROBLAZE) && \ + !defined(CONFIG_NIOS2) && \ + !defined(CONFIG_PPC32) && \ + !defined(CONFIG_SUPERH)) +# define TEST_U64 +#endif + +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; +} + +/* Test usage of check_nonzero_user(). */ +static void usercopy_test_check_nonzero_user(struct kunit *test) +{ + 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; + + KUNIT_ASSERT_GE_MSG(test, size, 2 * PAGE_SIZE, "buffer too small"); + + /* + * We want to cross a page boundary to exercise the code more + * effectively. We also don't want to make the size we scan too large, + * otherwise the test can take a long time and cause soft lockups. So + * scan a 1024 byte region across the page boundary. + */ + size = 1024; + start = PAGE_SIZE - (size / 2); + + kmem += start; + umem += start; + + zero_start = size / 4; + zero_end = size - zero_start; + + /* + * We conduct a series of check_nonzero_user() tests on a block of + * memory with the following byte-pattern (trying every possible + * [start,end] pair): + * + * [ 00 ff 00 ff ... 00 00 00 00 ... ff 00 ff 00 ] + * + * And we verify that check_nonzero_user() acts identically to + * memchr_inv(). + */ + + memset(kmem, 0x0, size); + for (i = 1; i < zero_start; i += 2) + kmem[i] = 0xff; + for (i = zero_end; i < size; i += 2) + kmem[i] = 0xff; + + 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++) { + size_t len = end - start; + int retval = check_zeroed_user(umem + start, len); + int expected = is_zeroed(kmem + start, len); + + KUNIT_ASSERT_EQ_MSG(test, retval, expected, + "check_nonzero_user(=%d) != memchr_inv(=%d) mismatch (start=%zu, end=%zu)", + retval, expected, start, end); + } + } +} + +/* Test usage of copy_struct_from_user(). */ +static void usercopy_test_copy_struct_from_user(struct kunit *test) +{ + 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 = kunit_kmalloc(test, size, GFP_KERNEL); + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, umem_src); + + 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); + KUNIT_ASSERT_EQ_MSG(test, copy_to_user(umem, umem_src, size), 0, + "legitimate copy_to_user failed"); + + /* Check basic case -- (usize == ksize). */ + ksize = size; + usize = size; + + memcpy(expected, umem_src, ksize); + + memset(kmem, 0x0, size); + KUNIT_EXPECT_EQ_MSG(test, copy_struct_from_user(kmem, ksize, umem, usize), 0, + "copy_struct_from_user(usize == ksize) failed"); + KUNIT_EXPECT_MEMEQ_MSG(test, kmem, expected, ksize, + "copy_struct_from_user(usize == ksize) gives unexpected copy"); + + /* Old userspace case -- (usize < ksize). */ + ksize = size; + usize = size / 2; + + memcpy(expected, umem_src, usize); + memset(expected + usize, 0x0, ksize - usize); + + memset(kmem, 0x0, size); + KUNIT_EXPECT_EQ_MSG(test, copy_struct_from_user(kmem, ksize, umem, usize), 0, + "copy_struct_from_user(usize < ksize) failed"); + KUNIT_EXPECT_MEMEQ_MSG(test, kmem, expected, ksize, + "copy_struct_from_user(usize < ksize) gives unexpected copy"); + + /* New userspace (-E2BIG) case -- (usize > ksize). */ + ksize = size / 2; + usize = size; + + memset(kmem, 0x0, size); + 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). */ + ksize = size / 2; + usize = size; + + memcpy(expected, umem_src, ksize); + KUNIT_EXPECT_EQ_MSG(test, clear_user(umem + ksize, usize - ksize), 0, + "legitimate clear_user failed"); + + memset(kmem, 0x0, size); + KUNIT_EXPECT_EQ_MSG(test, copy_struct_from_user(kmem, ksize, umem, usize), 0, + "copy_struct_from_user(usize > ksize) failed"); + KUNIT_EXPECT_MEMEQ_MSG(test, kmem, expected, ksize, + "copy_struct_from_user(usize > ksize) gives unexpected copy"); +} + +/* + * Legitimate usage: none of these copies should fail. + */ +static void usercopy_test_valid(struct kunit *test) +{ + struct usercopy_test_priv *priv = test->priv; + char __user *usermem = priv->umem; + char *kmem = priv->kmem; + + memset(kmem, 0x3a, PAGE_SIZE * 2); + KUNIT_EXPECT_EQ_MSG(test, 0, copy_to_user(usermem, kmem, PAGE_SIZE), + "legitimate copy_to_user failed"); + memset(kmem, 0x0, PAGE_SIZE); + KUNIT_EXPECT_EQ_MSG(test, 0, copy_from_user(kmem, usermem, PAGE_SIZE), + "legitimate copy_from_user failed"); + KUNIT_EXPECT_MEMEQ_MSG(test, 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); + test_legit(u16, 0x5a5b); + test_legit(u32, 0x5a5b5c5d); +#ifdef TEST_U64 + test_legit(u64, 0x5a5b5c5d6a6b6c6d); +#endif +#undef test_legit +} + +/* + * 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; + + if (IS_ENABLED(CONFIG_ALTERNATE_USER_ADDRESS_SPACE) || + !IS_ENABLED(CONFIG_MMU)) { + kunit_skip(test, "Testing for kernel/userspace address confusion is only sensible on architectures with a shared address space"); + return; + } + + /* 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(). */ + 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. */ + KUNIT_EXPECT_MEMEQ_MSG(test, kmem + PAGE_SIZE, kmem, PAGE_SIZE, + "zeroing failure for illegal all-kernel copy_from_user"); + +#if 0 + /* + * When running with SMAP/PAN/etc, this will Oops the kernel + * due to the zeroing of userspace memory on failure. This needs + * to be tested in LKDTM instead, since this test module does not + * expect to explode. + */ + KUNIT_EXPECT_NE_MSG(test, copy_from_user(bad_usermem, (char __user *)kmem, + PAGE_SIZE), 0, + "illegal reversed copy_from_user passed"); +#endif + KUNIT_EXPECT_NE_MSG(test, copy_to_user((char __user *)kmem, kmem + PAGE_SIZE, + PAGE_SIZE), 0, + "illegal all-kernel copy_to_user passed"); + + 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 { \ + 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); + test_illegal(u16, 0x5a5b); + test_illegal(u32, 0x5a5b5c5d); +#ifdef TEST_U64 + test_illegal(u64, 0x5a5b5c5d6a6b6c6d); +#endif +#undef test_illegal +} + +static int usercopy_test_init(struct kunit *test) +{ + struct usercopy_test_priv *priv; + unsigned long user_addr; + + if (!IS_ENABLED(CONFIG_MMU)) { + kunit_skip(test, "Userspace allocation testing not available on non-MMU systems"); + 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; + + priv->kmem = kunit_kmalloc(test, priv->size, GFP_KERNEL); + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, priv->kmem); + + user_addr = kunit_vm_mmap(test, NULL, 0, priv->size, + PROT_READ | PROT_WRITE | PROT_EXEC, + MAP_ANONYMOUS | MAP_PRIVATE, 0); + KUNIT_ASSERT_NE_MSG(test, user_addr, 0, + "Could not create userspace mm"); + KUNIT_ASSERT_LT_MSG(test, user_addr, (unsigned long)TASK_SIZE, + "Failed to allocate user memory"); + priv->umem = (char __user *)user_addr; + + return 0; +} + +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_DESCRIPTION("Kernel module for testing copy_to/from_user infrastructure"); +MODULE_LICENSE("GPL"); |