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331 lines
9.1 KiB
331 lines
9.1 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* Kernel module for testing copy_to/from_user infrastructure. |
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* |
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* Copyright 2013 Google Inc. All Rights Reserved |
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* |
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* Authors: |
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* Kees Cook <[email protected]> |
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*/ |
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
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#include <linux/mman.h> |
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#include <linux/module.h> |
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#include <linux/sched.h> |
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#include <linux/slab.h> |
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#include <linux/uaccess.h> |
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#include <linux/vmalloc.h> |
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/* |
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* Several 32-bit architectures support 64-bit {get,put}_user() calls. |
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* As there doesn't appear to be anything that can safely determine |
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* their capability at compile-time, we just have to opt-out certain archs. |
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*/ |
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#if BITS_PER_LONG == 64 || (!(defined(CONFIG_ARM) && !defined(MMU)) && \ |
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!defined(CONFIG_M68K) && \ |
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!defined(CONFIG_MICROBLAZE) && \ |
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!defined(CONFIG_NIOS2) && \ |
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!defined(CONFIG_PPC32) && \ |
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!defined(CONFIG_SUPERH)) |
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# define TEST_U64 |
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#endif |
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#define test(condition, msg, ...) \ |
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({ \ |
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int cond = (condition); \ |
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if (cond) \ |
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pr_warn("[%d] " msg "\n", __LINE__, ##__VA_ARGS__); \ |
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cond; \ |
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}) |
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static bool is_zeroed(void *from, size_t size) |
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{ |
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return memchr_inv(from, 0x0, size) == NULL; |
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} |
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static int test_check_nonzero_user(char *kmem, char __user *umem, size_t size) |
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{ |
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int ret = 0; |
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size_t start, end, i, zero_start, zero_end; |
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if (test(size < 2 * PAGE_SIZE, "buffer too small")) |
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return -EINVAL; |
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/* |
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* We want to cross a page boundary to exercise the code more |
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* effectively. We also don't want to make the size we scan too large, |
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* otherwise the test can take a long time and cause soft lockups. So |
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* scan a 1024 byte region across the page boundary. |
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*/ |
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size = 1024; |
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start = PAGE_SIZE - (size / 2); |
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kmem += start; |
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umem += start; |
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zero_start = size / 4; |
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zero_end = size - zero_start; |
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/* |
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* We conduct a series of check_nonzero_user() tests on a block of |
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* memory with the following byte-pattern (trying every possible |
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* [start,end] pair): |
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* |
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* [ 00 ff 00 ff ... 00 00 00 00 ... ff 00 ff 00 ] |
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* |
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* And we verify that check_nonzero_user() acts identically to |
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* memchr_inv(). |
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*/ |
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memset(kmem, 0x0, size); |
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for (i = 1; i < zero_start; i += 2) |
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kmem[i] = 0xff; |
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for (i = zero_end; i < size; i += 2) |
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kmem[i] = 0xff; |
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ret |= test(copy_to_user(umem, kmem, size), |
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"legitimate copy_to_user failed"); |
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for (start = 0; start <= size; start++) { |
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for (end = start; end <= size; end++) { |
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size_t len = end - start; |
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int retval = check_zeroed_user(umem + start, len); |
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int expected = is_zeroed(kmem + start, len); |
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ret |= test(retval != expected, |
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"check_nonzero_user(=%d) != memchr_inv(=%d) mismatch (start=%zu, end=%zu)", |
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retval, expected, start, end); |
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} |
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} |
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return ret; |
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} |
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static int test_copy_struct_from_user(char *kmem, char __user *umem, |
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size_t size) |
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{ |
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int ret = 0; |
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char *umem_src = NULL, *expected = NULL; |
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size_t ksize, usize; |
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umem_src = kmalloc(size, GFP_KERNEL); |
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ret = test(umem_src == NULL, "kmalloc failed"); |
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if (ret) |
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goto out_free; |
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expected = kmalloc(size, GFP_KERNEL); |
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ret = test(expected == NULL, "kmalloc failed"); |
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if (ret) |
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goto out_free; |
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/* Fill umem with a fixed byte pattern. */ |
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memset(umem_src, 0x3e, size); |
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ret |= test(copy_to_user(umem, umem_src, size), |
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"legitimate copy_to_user failed"); |
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/* Check basic case -- (usize == ksize). */ |
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ksize = size; |
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usize = size; |
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memcpy(expected, umem_src, ksize); |
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memset(kmem, 0x0, size); |
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ret |= test(copy_struct_from_user(kmem, ksize, umem, usize), |
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"copy_struct_from_user(usize == ksize) failed"); |
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ret |= test(memcmp(kmem, expected, ksize), |
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"copy_struct_from_user(usize == ksize) gives unexpected copy"); |
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/* Old userspace case -- (usize < ksize). */ |
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ksize = size; |
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usize = size / 2; |
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memcpy(expected, umem_src, usize); |
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memset(expected + usize, 0x0, ksize - usize); |
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memset(kmem, 0x0, size); |
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ret |= test(copy_struct_from_user(kmem, ksize, umem, usize), |
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"copy_struct_from_user(usize < ksize) failed"); |
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ret |= test(memcmp(kmem, expected, ksize), |
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"copy_struct_from_user(usize < ksize) gives unexpected copy"); |
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/* New userspace (-E2BIG) case -- (usize > ksize). */ |
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ksize = size / 2; |
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usize = size; |
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memset(kmem, 0x0, size); |
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ret |= test(copy_struct_from_user(kmem, ksize, umem, usize) != -E2BIG, |
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"copy_struct_from_user(usize > ksize) didn't give E2BIG"); |
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/* New userspace (success) case -- (usize > ksize). */ |
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ksize = size / 2; |
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usize = size; |
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memcpy(expected, umem_src, ksize); |
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ret |= test(clear_user(umem + ksize, usize - ksize), |
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"legitimate clear_user failed"); |
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memset(kmem, 0x0, size); |
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ret |= test(copy_struct_from_user(kmem, ksize, umem, usize), |
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"copy_struct_from_user(usize > ksize) failed"); |
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ret |= test(memcmp(kmem, expected, ksize), |
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"copy_struct_from_user(usize > ksize) gives unexpected copy"); |
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out_free: |
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kfree(expected); |
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kfree(umem_src); |
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return ret; |
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} |
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static int __init test_user_copy_init(void) |
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{ |
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int ret = 0; |
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char *kmem; |
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char __user *usermem; |
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char *bad_usermem; |
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unsigned long user_addr; |
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u8 val_u8; |
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u16 val_u16; |
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u32 val_u32; |
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#ifdef TEST_U64 |
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u64 val_u64; |
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#endif |
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kmem = kmalloc(PAGE_SIZE * 2, GFP_KERNEL); |
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if (!kmem) |
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return -ENOMEM; |
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user_addr = vm_mmap(NULL, 0, PAGE_SIZE * 2, |
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PROT_READ | PROT_WRITE | PROT_EXEC, |
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MAP_ANONYMOUS | MAP_PRIVATE, 0); |
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if (user_addr >= (unsigned long)(TASK_SIZE)) { |
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pr_warn("Failed to allocate user memory\n"); |
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kfree(kmem); |
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return -ENOMEM; |
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} |
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usermem = (char __user *)user_addr; |
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bad_usermem = (char *)user_addr; |
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/* |
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* Legitimate usage: none of these copies should fail. |
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*/ |
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memset(kmem, 0x3a, PAGE_SIZE * 2); |
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ret |= test(copy_to_user(usermem, kmem, PAGE_SIZE), |
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"legitimate copy_to_user failed"); |
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memset(kmem, 0x0, PAGE_SIZE); |
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ret |= test(copy_from_user(kmem, usermem, PAGE_SIZE), |
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"legitimate copy_from_user failed"); |
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ret |= test(memcmp(kmem, kmem + PAGE_SIZE, PAGE_SIZE), |
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"legitimate usercopy failed to copy data"); |
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#define test_legit(size, check) \ |
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do { \ |
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val_##size = check; \ |
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ret |= test(put_user(val_##size, (size __user *)usermem), \ |
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"legitimate put_user (" #size ") failed"); \ |
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val_##size = 0; \ |
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ret |= test(get_user(val_##size, (size __user *)usermem), \ |
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"legitimate get_user (" #size ") failed"); \ |
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ret |= test(val_##size != check, \ |
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"legitimate get_user (" #size ") failed to do copy"); \ |
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if (val_##size != check) { \ |
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pr_info("0x%llx != 0x%llx\n", \ |
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(unsigned long long)val_##size, \ |
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(unsigned long long)check); \ |
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} \ |
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} while (0) |
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test_legit(u8, 0x5a); |
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test_legit(u16, 0x5a5b); |
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test_legit(u32, 0x5a5b5c5d); |
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#ifdef TEST_U64 |
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test_legit(u64, 0x5a5b5c5d6a6b6c6d); |
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#endif |
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#undef test_legit |
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/* Test usage of check_nonzero_user(). */ |
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ret |= test_check_nonzero_user(kmem, usermem, 2 * PAGE_SIZE); |
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/* Test usage of copy_struct_from_user(). */ |
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ret |= test_copy_struct_from_user(kmem, usermem, 2 * PAGE_SIZE); |
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/* |
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* Invalid usage: none of these copies should succeed. |
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*/ |
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/* Prepare kernel memory with check values. */ |
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memset(kmem, 0x5a, PAGE_SIZE); |
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memset(kmem + PAGE_SIZE, 0, PAGE_SIZE); |
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/* Reject kernel-to-kernel copies through copy_from_user(). */ |
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ret |= test(!copy_from_user(kmem, (char __user *)(kmem + PAGE_SIZE), |
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PAGE_SIZE), |
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"illegal all-kernel copy_from_user passed"); |
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/* Destination half of buffer should have been zeroed. */ |
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ret |= test(memcmp(kmem + PAGE_SIZE, kmem, PAGE_SIZE), |
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"zeroing failure for illegal all-kernel copy_from_user"); |
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#if 0 |
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/* |
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* When running with SMAP/PAN/etc, this will Oops the kernel |
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* due to the zeroing of userspace memory on failure. This needs |
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* to be tested in LKDTM instead, since this test module does not |
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* expect to explode. |
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*/ |
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ret |= test(!copy_from_user(bad_usermem, (char __user *)kmem, |
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PAGE_SIZE), |
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"illegal reversed copy_from_user passed"); |
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#endif |
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ret |= test(!copy_to_user((char __user *)kmem, kmem + PAGE_SIZE, |
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PAGE_SIZE), |
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"illegal all-kernel copy_to_user passed"); |
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ret |= test(!copy_to_user((char __user *)kmem, bad_usermem, |
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PAGE_SIZE), |
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"illegal reversed copy_to_user passed"); |
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#define test_illegal(size, check) \ |
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do { \ |
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val_##size = (check); \ |
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ret |= test(!get_user(val_##size, (size __user *)kmem), \ |
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"illegal get_user (" #size ") passed"); \ |
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ret |= test(val_##size != (size)0, \ |
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"zeroing failure for illegal get_user (" #size ")"); \ |
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if (val_##size != (size)0) { \ |
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pr_info("0x%llx != 0\n", \ |
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(unsigned long long)val_##size); \ |
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} \ |
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ret |= test(!put_user(val_##size, (size __user *)kmem), \ |
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"illegal put_user (" #size ") passed"); \ |
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} while (0) |
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test_illegal(u8, 0x5a); |
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test_illegal(u16, 0x5a5b); |
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test_illegal(u32, 0x5a5b5c5d); |
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#ifdef TEST_U64 |
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test_illegal(u64, 0x5a5b5c5d6a6b6c6d); |
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#endif |
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#undef test_illegal |
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vm_munmap(user_addr, PAGE_SIZE * 2); |
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kfree(kmem); |
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if (ret == 0) { |
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pr_info("tests passed.\n"); |
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return 0; |
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} |
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return -EINVAL; |
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} |
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module_init(test_user_copy_init); |
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static void __exit test_user_copy_exit(void) |
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{ |
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pr_info("unloaded.\n"); |
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} |
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module_exit(test_user_copy_exit); |
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MODULE_AUTHOR("Kees Cook <[email protected]>"); |
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MODULE_LICENSE("GPL");
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