mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-24 05:04:00 +08:00
f418dddffc
On a machine with a 64K PAGE_SIZE, the nested for loops in
test_check_nonzero_user() can lead to soft lockups, eg:
watchdog: BUG: soft lockup - CPU#4 stuck for 22s! [modprobe:611]
Modules linked in: test_user_copy(+) vmx_crypto gf128mul crc32c_vpmsum virtio_balloon ip_tables x_tables autofs4
CPU: 4 PID: 611 Comm: modprobe Tainted: G L 5.4.0-rc1-gcc-8.2.0-00001-gf5a1a536fa14-dirty #1151
...
NIP __might_sleep+0x20/0xc0
LR __might_fault+0x40/0x60
Call Trace:
check_zeroed_user+0x12c/0x200
test_user_copy_init+0x67c/0x1210 [test_user_copy]
do_one_initcall+0x60/0x340
do_init_module+0x7c/0x2f0
load_module+0x2d94/0x30e0
__do_sys_finit_module+0xc8/0x150
system_call+0x5c/0x68
Even with a 4K PAGE_SIZE the test takes multiple seconds. Instead
tweak it to only scan a 1024 byte region, but make it cross the
page boundary.
Fixes: f5a1a536fa
("lib: introduce copy_struct_from_user() helper")
Suggested-by: Aleksa Sarai <cyphar@cyphar.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Aleksa Sarai <cyphar@cyphar.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Link: https://lore.kernel.org/r/20191016122732.13467-1-mpe@ellerman.id.au
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
332 lines
9.1 KiB
C
332 lines
9.1 KiB
C
// 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 <linux/vmalloc.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
|
|
|
|
#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)
|
|
{
|
|
int ret = 0;
|
|
size_t start, end, i, zero_start, zero_end;
|
|
|
|
if (test(size < 2 * PAGE_SIZE, "buffer too small"))
|
|
return -EINVAL;
|
|
|
|
/*
|
|
* 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;
|
|
|
|
ret |= test(copy_to_user(umem, kmem, size),
|
|
"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);
|
|
|
|
ret |= 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)
|
|
{
|
|
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;
|
|
|
|
expected = kmalloc(size, GFP_KERNEL);
|
|
ret = test(expected == NULL, "kmalloc failed");
|
|
if (ret)
|
|
goto out_free;
|
|
|
|
/* Fill umem with a fixed byte pattern. */
|
|
memset(umem_src, 0x3e, size);
|
|
ret |= test(copy_to_user(umem, umem_src, size),
|
|
"legitimate copy_to_user failed");
|
|
|
|
/* Check basic case -- (usize == ksize). */
|
|
ksize = size;
|
|
usize = size;
|
|
|
|
memcpy(expected, umem_src, ksize);
|
|
|
|
memset(kmem, 0x0, size);
|
|
ret |= test(copy_struct_from_user(kmem, ksize, umem, usize),
|
|
"copy_struct_from_user(usize == ksize) failed");
|
|
ret |= test(memcmp(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);
|
|
ret |= test(copy_struct_from_user(kmem, ksize, umem, usize),
|
|
"copy_struct_from_user(usize < ksize) failed");
|
|
ret |= test(memcmp(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);
|
|
ret |= 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);
|
|
ret |= 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),
|
|
"copy_struct_from_user(usize > ksize) failed");
|
|
ret |= 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)
|
|
{
|
|
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;
|
|
|
|
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");
|
|
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); \
|
|
} \
|
|
} 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
|
|
|
|
/* 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.
|
|
*/
|
|
|
|
/* 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),
|
|
"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");
|
|
|
|
#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.
|
|
*/
|
|
ret |= 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"); \
|
|
} 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
|
|
|
|
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");
|
|
}
|
|
|
|
module_exit(test_user_copy_exit);
|
|
|
|
MODULE_AUTHOR("Kees Cook <keescook@chromium.org>");
|
|
MODULE_LICENSE("GPL");
|