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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Kernel module for testing copy_to/from_user infrastructure.4 *5 * Copyright 2013 Google Inc. All Rights Reserved6 *7 * Authors:8 * Kees Cook <keescook@chromium.org>9 */10 11#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt12 13#include <linux/mman.h>14#include <linux/module.h>15#include <linux/sched.h>16#include <linux/slab.h>17#include <linux/uaccess.h>18#include <kunit/test.h>19 20/*21 * Several 32-bit architectures support 64-bit {get,put}_user() calls.22 * As there doesn't appear to be anything that can safely determine23 * their capability at compile-time, we just have to opt-out certain archs.24 */25#if BITS_PER_LONG == 64 || (!(defined(CONFIG_ARM) && !defined(MMU)) && \26 !defined(CONFIG_M68K) && \27 !defined(CONFIG_MICROBLAZE) && \28 !defined(CONFIG_NIOS2) && \29 !defined(CONFIG_PPC32) && \30 !defined(CONFIG_SUPERH))31# define TEST_U6432#endif33 34struct usercopy_test_priv {35 char *kmem;36 char __user *umem;37 size_t size;38};39 40static bool is_zeroed(void *from, size_t size)41{42 return memchr_inv(from, 0x0, size) == NULL;43}44 45/* Test usage of check_nonzero_user(). */46static void usercopy_test_check_nonzero_user(struct kunit *test)47{48 size_t start, end, i, zero_start, zero_end;49 struct usercopy_test_priv *priv = test->priv;50 char __user *umem = priv->umem;51 char *kmem = priv->kmem;52 size_t size = priv->size;53 54 KUNIT_ASSERT_GE_MSG(test, size, 2 * PAGE_SIZE, "buffer too small");55 56 /*57 * We want to cross a page boundary to exercise the code more58 * effectively. We also don't want to make the size we scan too large,59 * otherwise the test can take a long time and cause soft lockups. So60 * scan a 1024 byte region across the page boundary.61 */62 size = 1024;63 start = PAGE_SIZE - (size / 2);64 65 kmem += start;66 umem += start;67 68 zero_start = size / 4;69 zero_end = size - zero_start;70 71 /*72 * We conduct a series of check_nonzero_user() tests on a block of73 * memory with the following byte-pattern (trying every possible74 * [start,end] pair):75 *76 * [ 00 ff 00 ff ... 00 00 00 00 ... ff 00 ff 00 ]77 *78 * And we verify that check_nonzero_user() acts identically to79 * memchr_inv().80 */81 82 memset(kmem, 0x0, size);83 for (i = 1; i < zero_start; i += 2)84 kmem[i] = 0xff;85 for (i = zero_end; i < size; i += 2)86 kmem[i] = 0xff;87 88 KUNIT_EXPECT_EQ_MSG(test, copy_to_user(umem, kmem, size), 0,89 "legitimate copy_to_user failed");90 91 for (start = 0; start <= size; start++) {92 for (end = start; end <= size; end++) {93 size_t len = end - start;94 int retval = check_zeroed_user(umem + start, len);95 int expected = is_zeroed(kmem + start, len);96 97 KUNIT_ASSERT_EQ_MSG(test, retval, expected,98 "check_nonzero_user(=%d) != memchr_inv(=%d) mismatch (start=%zu, end=%zu)",99 retval, expected, start, end);100 }101 }102}103 104/* Test usage of copy_struct_from_user(). */105static void usercopy_test_copy_struct_from_user(struct kunit *test)106{107 char *umem_src = NULL, *expected = NULL;108 struct usercopy_test_priv *priv = test->priv;109 char __user *umem = priv->umem;110 char *kmem = priv->kmem;111 size_t size = priv->size;112 size_t ksize, usize;113 114 umem_src = kunit_kmalloc(test, size, GFP_KERNEL);115 KUNIT_ASSERT_NOT_ERR_OR_NULL(test, umem_src);116 117 expected = kunit_kmalloc(test, size, GFP_KERNEL);118 KUNIT_ASSERT_NOT_ERR_OR_NULL(test, expected);119 120 /* Fill umem with a fixed byte pattern. */121 memset(umem_src, 0x3e, size);122 KUNIT_ASSERT_EQ_MSG(test, copy_to_user(umem, umem_src, size), 0,123 "legitimate copy_to_user failed");124 125 /* Check basic case -- (usize == ksize). */126 ksize = size;127 usize = size;128 129 memcpy(expected, umem_src, ksize);130 131 memset(kmem, 0x0, size);132 KUNIT_EXPECT_EQ_MSG(test, copy_struct_from_user(kmem, ksize, umem, usize), 0,133 "copy_struct_from_user(usize == ksize) failed");134 KUNIT_EXPECT_MEMEQ_MSG(test, kmem, expected, ksize,135 "copy_struct_from_user(usize == ksize) gives unexpected copy");136 137 /* Old userspace case -- (usize < ksize). */138 ksize = size;139 usize = size / 2;140 141 memcpy(expected, umem_src, usize);142 memset(expected + usize, 0x0, ksize - usize);143 144 memset(kmem, 0x0, size);145 KUNIT_EXPECT_EQ_MSG(test, copy_struct_from_user(kmem, ksize, umem, usize), 0,146 "copy_struct_from_user(usize < ksize) failed");147 KUNIT_EXPECT_MEMEQ_MSG(test, kmem, expected, ksize,148 "copy_struct_from_user(usize < ksize) gives unexpected copy");149 150 /* New userspace (-E2BIG) case -- (usize > ksize). */151 ksize = size / 2;152 usize = size;153 154 memset(kmem, 0x0, size);155 KUNIT_EXPECT_EQ_MSG(test, copy_struct_from_user(kmem, ksize, umem, usize), -E2BIG,156 "copy_struct_from_user(usize > ksize) didn't give E2BIG");157 158 /* New userspace (success) case -- (usize > ksize). */159 ksize = size / 2;160 usize = size;161 162 memcpy(expected, umem_src, ksize);163 KUNIT_EXPECT_EQ_MSG(test, clear_user(umem + ksize, usize - ksize), 0,164 "legitimate clear_user failed");165 166 memset(kmem, 0x0, size);167 KUNIT_EXPECT_EQ_MSG(test, copy_struct_from_user(kmem, ksize, umem, usize), 0,168 "copy_struct_from_user(usize > ksize) failed");169 KUNIT_EXPECT_MEMEQ_MSG(test, kmem, expected, ksize,170 "copy_struct_from_user(usize > ksize) gives unexpected copy");171}172 173/*174 * Legitimate usage: none of these copies should fail.175 */176static void usercopy_test_valid(struct kunit *test)177{178 struct usercopy_test_priv *priv = test->priv;179 char __user *usermem = priv->umem;180 char *kmem = priv->kmem;181 182 memset(kmem, 0x3a, PAGE_SIZE * 2);183 KUNIT_EXPECT_EQ_MSG(test, 0, copy_to_user(usermem, kmem, PAGE_SIZE),184 "legitimate copy_to_user failed");185 memset(kmem, 0x0, PAGE_SIZE);186 KUNIT_EXPECT_EQ_MSG(test, 0, copy_from_user(kmem, usermem, PAGE_SIZE),187 "legitimate copy_from_user failed");188 KUNIT_EXPECT_MEMEQ_MSG(test, kmem, kmem + PAGE_SIZE, PAGE_SIZE,189 "legitimate usercopy failed to copy data");190 191#define test_legit(size, check) \192 do { \193 size val_##size = (check); \194 KUNIT_EXPECT_EQ_MSG(test, 0, \195 put_user(val_##size, (size __user *)usermem), \196 "legitimate put_user (" #size ") failed"); \197 val_##size = 0; \198 KUNIT_EXPECT_EQ_MSG(test, 0, \199 get_user(val_##size, (size __user *)usermem), \200 "legitimate get_user (" #size ") failed"); \201 KUNIT_EXPECT_EQ_MSG(test, val_##size, check, \202 "legitimate get_user (" #size ") failed to do copy"); \203 } while (0)204 205 test_legit(u8, 0x5a);206 test_legit(u16, 0x5a5b);207 test_legit(u32, 0x5a5b5c5d);208#ifdef TEST_U64209 test_legit(u64, 0x5a5b5c5d6a6b6c6d);210#endif211#undef test_legit212}213 214/*215 * Invalid usage: none of these copies should succeed.216 */217static void usercopy_test_invalid(struct kunit *test)218{219 struct usercopy_test_priv *priv = test->priv;220 char __user *usermem = priv->umem;221 char *bad_usermem = (char *)usermem;222 char *kmem = priv->kmem;223 u64 *kmem_u64 = (u64 *)kmem;224 225 if (IS_ENABLED(CONFIG_ALTERNATE_USER_ADDRESS_SPACE) ||226 !IS_ENABLED(CONFIG_MMU)) {227 kunit_skip(test, "Testing for kernel/userspace address confusion is only sensible on architectures with a shared address space");228 return;229 }230 231 /* Prepare kernel memory with check values. */232 memset(kmem, 0x5a, PAGE_SIZE);233 memset(kmem + PAGE_SIZE, 0, PAGE_SIZE);234 235 /* Reject kernel-to-kernel copies through copy_from_user(). */236 KUNIT_EXPECT_NE_MSG(test, copy_from_user(kmem, (char __user *)(kmem + PAGE_SIZE),237 PAGE_SIZE), 0,238 "illegal all-kernel copy_from_user passed");239 240 /* Destination half of buffer should have been zeroed. */241 KUNIT_EXPECT_MEMEQ_MSG(test, kmem + PAGE_SIZE, kmem, PAGE_SIZE,242 "zeroing failure for illegal all-kernel copy_from_user");243 244#if 0245 /*246 * When running with SMAP/PAN/etc, this will Oops the kernel247 * due to the zeroing of userspace memory on failure. This needs248 * to be tested in LKDTM instead, since this test module does not249 * expect to explode.250 */251 KUNIT_EXPECT_NE_MSG(test, copy_from_user(bad_usermem, (char __user *)kmem,252 PAGE_SIZE), 0,253 "illegal reversed copy_from_user passed");254#endif255 KUNIT_EXPECT_NE_MSG(test, copy_to_user((char __user *)kmem, kmem + PAGE_SIZE,256 PAGE_SIZE), 0,257 "illegal all-kernel copy_to_user passed");258 259 KUNIT_EXPECT_NE_MSG(test, copy_to_user((char __user *)kmem, bad_usermem,260 PAGE_SIZE), 0,261 "illegal reversed copy_to_user passed");262 263#define test_illegal(size, check) \264 do { \265 size val_##size = (check); \266 /* get_user() */ \267 KUNIT_EXPECT_NE_MSG(test, get_user(val_##size, (size __user *)kmem), 0, \268 "illegal get_user (" #size ") passed"); \269 KUNIT_EXPECT_EQ_MSG(test, val_##size, 0, \270 "zeroing failure for illegal get_user (" #size ")"); \271 /* put_user() */ \272 *kmem_u64 = 0xF09FA4AFF09FA4AF; \273 KUNIT_EXPECT_NE_MSG(test, put_user(val_##size, (size __user *)kmem), 0, \274 "illegal put_user (" #size ") passed"); \275 KUNIT_EXPECT_EQ_MSG(test, *kmem_u64, 0xF09FA4AFF09FA4AF, \276 "illegal put_user (" #size ") wrote to kernel memory!"); \277 } while (0)278 279 test_illegal(u8, 0x5a);280 test_illegal(u16, 0x5a5b);281 test_illegal(u32, 0x5a5b5c5d);282#ifdef TEST_U64283 test_illegal(u64, 0x5a5b5c5d6a6b6c6d);284#endif285#undef test_illegal286}287 288static int usercopy_test_init(struct kunit *test)289{290 struct usercopy_test_priv *priv;291 unsigned long user_addr;292 293 if (!IS_ENABLED(CONFIG_MMU)) {294 kunit_skip(test, "Userspace allocation testing not available on non-MMU systems");295 return 0;296 }297 298 priv = kunit_kzalloc(test, sizeof(*priv), GFP_KERNEL);299 KUNIT_ASSERT_NOT_ERR_OR_NULL(test, priv);300 test->priv = priv;301 priv->size = PAGE_SIZE * 2;302 303 priv->kmem = kunit_kmalloc(test, priv->size, GFP_KERNEL);304 KUNIT_ASSERT_NOT_ERR_OR_NULL(test, priv->kmem);305 306 user_addr = kunit_vm_mmap(test, NULL, 0, priv->size,307 PROT_READ | PROT_WRITE | PROT_EXEC,308 MAP_ANONYMOUS | MAP_PRIVATE, 0);309 KUNIT_ASSERT_NE_MSG(test, user_addr, 0,310 "Could not create userspace mm");311 KUNIT_ASSERT_LT_MSG(test, user_addr, (unsigned long)TASK_SIZE,312 "Failed to allocate user memory");313 priv->umem = (char __user *)user_addr;314 315 return 0;316}317 318static struct kunit_case usercopy_test_cases[] = {319 KUNIT_CASE(usercopy_test_valid),320 KUNIT_CASE(usercopy_test_invalid),321 KUNIT_CASE(usercopy_test_check_nonzero_user),322 KUNIT_CASE(usercopy_test_copy_struct_from_user),323 {}324};325 326static struct kunit_suite usercopy_test_suite = {327 .name = "usercopy",328 .init = usercopy_test_init,329 .test_cases = usercopy_test_cases,330};331 332kunit_test_suites(&usercopy_test_suite);333MODULE_AUTHOR("Kees Cook <kees@kernel.org>");334MODULE_DESCRIPTION("Kernel module for testing copy_to/from_user infrastructure");335MODULE_LICENSE("GPL");336