1 /* 2 * Kernel module for testing copy_to/from_user infrastructure. 3 * 4 * Copyright 2013 Google Inc. All Rights Reserved 5 * 6 * Authors: 7 * Kees Cook <keescook@chromium.org> 8 * 9 * This software is licensed under the terms of the GNU General Public 10 * License version 2, as published by the Free Software Foundation, and 11 * may be copied, distributed, and modified under those terms. 12 * 13 * This program is distributed in the hope that it will be useful, 14 * but WITHOUT ANY WARRANTY; without even the implied warranty of 15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 * GNU General Public License for more details. 17 */ 18 19 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 20 21 #include <linux/mman.h> 22 #include <linux/module.h> 23 #include <linux/sched.h> 24 #include <linux/slab.h> 25 #include <linux/uaccess.h> 26 #include <linux/vmalloc.h> 27 28 #define test(condition, msg) \ 29 ({ \ 30 int cond = (condition); \ 31 if (cond) \ 32 pr_warn("%s\n", msg); \ 33 cond; \ 34 }) 35 36 static int __init test_user_copy_init(void) 37 { 38 int ret = 0; 39 char *kmem; 40 char __user *usermem; 41 char *bad_usermem; 42 unsigned long user_addr; 43 unsigned long value = 0x5A; 44 45 kmem = kmalloc(PAGE_SIZE * 2, GFP_KERNEL); 46 if (!kmem) 47 return -ENOMEM; 48 49 user_addr = vm_mmap(NULL, 0, PAGE_SIZE * 2, 50 PROT_READ | PROT_WRITE | PROT_EXEC, 51 MAP_ANONYMOUS | MAP_PRIVATE, 0); 52 if (user_addr >= (unsigned long)(TASK_SIZE)) { 53 pr_warn("Failed to allocate user memory\n"); 54 kfree(kmem); 55 return -ENOMEM; 56 } 57 58 usermem = (char __user *)user_addr; 59 bad_usermem = (char *)user_addr; 60 61 /* Legitimate usage: none of these should fail. */ 62 ret |= test(copy_from_user(kmem, usermem, PAGE_SIZE), 63 "legitimate copy_from_user failed"); 64 ret |= test(copy_to_user(usermem, kmem, PAGE_SIZE), 65 "legitimate copy_to_user failed"); 66 ret |= test(get_user(value, (unsigned long __user *)usermem), 67 "legitimate get_user failed"); 68 ret |= test(put_user(value, (unsigned long __user *)usermem), 69 "legitimate put_user failed"); 70 71 /* Invalid usage: none of these should succeed. */ 72 ret |= test(!copy_from_user(kmem, (char __user *)(kmem + PAGE_SIZE), 73 PAGE_SIZE), 74 "illegal all-kernel copy_from_user passed"); 75 ret |= test(!copy_from_user(bad_usermem, (char __user *)kmem, 76 PAGE_SIZE), 77 "illegal reversed copy_from_user passed"); 78 ret |= test(!copy_to_user((char __user *)kmem, kmem + PAGE_SIZE, 79 PAGE_SIZE), 80 "illegal all-kernel copy_to_user passed"); 81 ret |= test(!copy_to_user((char __user *)kmem, bad_usermem, 82 PAGE_SIZE), 83 "illegal reversed copy_to_user passed"); 84 ret |= test(!get_user(value, (unsigned long __user *)kmem), 85 "illegal get_user passed"); 86 ret |= test(!put_user(value, (unsigned long __user *)kmem), 87 "illegal put_user passed"); 88 89 vm_munmap(user_addr, PAGE_SIZE * 2); 90 kfree(kmem); 91 92 if (ret == 0) { 93 pr_info("tests passed.\n"); 94 return 0; 95 } 96 97 return -EINVAL; 98 } 99 100 module_init(test_user_copy_init); 101 102 static void __exit test_user_copy_exit(void) 103 { 104 pr_info("unloaded.\n"); 105 } 106 107 module_exit(test_user_copy_exit); 108 109 MODULE_AUTHOR("Kees Cook <keescook@chromium.org>"); 110 MODULE_LICENSE("GPL"); 111