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Diffstat (limited to '')
| -rw-r--r-- | lib/test_user_copy.c | 196 |
1 files changed, 196 insertions, 0 deletions
diff --git a/lib/test_user_copy.c b/lib/test_user_copy.c new file mode 100644 index 000000000..e161f0498 --- /dev/null +++ b/lib/test_user_copy.c @@ -0,0 +1,196 @@ +/* + * Kernel module for testing copy_to/from_user infrastructure. + * + * Copyright 2013 Google Inc. All Rights Reserved + * + * Authors: + * Kees Cook <keescook@chromium.org> + * + * This software is licensed under the terms of the GNU General Public + * License version 2, as published by the Free Software Foundation, and + * may be copied, distributed, and modified under those terms. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#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("%s\n", msg); \ + cond; \ +}) + +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 + + /* + * 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"); |