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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 | /* * 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> #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; unsigned long value = 0x5A; 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 should fail. */ ret |= test(copy_from_user(kmem, usermem, PAGE_SIZE), "legitimate copy_from_user failed"); ret |= test(copy_to_user(usermem, kmem, PAGE_SIZE), "legitimate copy_to_user failed"); ret |= test(get_user(value, (unsigned long __user *)usermem), "legitimate get_user failed"); ret |= test(put_user(value, (unsigned long __user *)usermem), "legitimate put_user failed"); /* Invalid usage: none of these should succeed. */ ret |= test(!copy_from_user(kmem, (char __user *)(kmem + PAGE_SIZE), PAGE_SIZE), "illegal all-kernel copy_from_user passed"); ret |= test(!copy_from_user(bad_usermem, (char __user *)kmem, PAGE_SIZE), "illegal reversed copy_from_user passed"); 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"); ret |= test(!get_user(value, (unsigned long __user *)kmem), "illegal get_user passed"); ret |= test(!put_user(value, (unsigned long __user *)kmem), "illegal put_user passed"); 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"); |