| /* |
| * Copyright (c) 2019 Intel Corporation. |
| * |
| * SPDX-License-Identifier: Apache-2.0 |
| */ |
| |
| #include <zephyr/syscall_handler.h> |
| #include <zephyr/logging/log.h> |
| |
| LOG_MODULE_REGISTER(app_syscall); |
| |
| /* Implementation of magic_syscall() which is a system call just for this |
| * application, not part of the kernel codebase. |
| * |
| * It's trivial, update the supplied cookie value by 1, only if it is less than |
| * 42. This is just for demonstration purposes to show how syscalls can be |
| * defined in application code. |
| */ |
| int z_impl_magic_syscall(unsigned int *cookie) |
| { |
| LOG_DBG("magic syscall: got a cookie %u", *cookie); |
| |
| if (*cookie > 42) { |
| LOG_ERR("bad cookie :("); |
| return -EINVAL; |
| } |
| |
| *cookie = *cookie + 1; |
| |
| return 0; |
| } |
| |
| static int z_vrfy_magic_syscall(unsigned int *cookie) |
| { |
| unsigned int cookie_copy; |
| int ret; |
| |
| /* Confirm that this user-supplied pointer is valid memory that |
| * can be accessed. If it's OK, copy into cookie_copy. |
| */ |
| if (z_user_from_copy(&cookie_copy, cookie, sizeof(*cookie)) != 0) { |
| return -EPERM; |
| } |
| |
| /* We pass to the implementation the *copy*, to prevent TOCTOU attacks |
| */ |
| ret = z_impl_magic_syscall(&cookie_copy); |
| |
| if (ret == 0 && |
| z_user_to_copy(cookie, &cookie_copy, sizeof(*cookie)) != 0) { |
| return -EPERM; |
| } |
| |
| return ret; |
| } |
| |
| #include <syscalls/magic_syscall_mrsh.c> |
