/* * Copyright (c) 2017, Intel Corporation * * SPDX-License-Identifier: Apache 2.0 */ #ifndef _ZEPHYR_SYSCALL_HANDLER_H_ #define _ZEPHYR_SYSCALL_HANDLER_H_ #ifdef CONFIG_USERSPACE #ifndef _ASMLANGUAGE #include #include #include extern const _k_syscall_handler_t _k_syscall_table[K_SYSCALL_LIMIT]; /** * Ensure a system object is a valid object of the expected type * * Searches for the object and ensures that it is indeed an object * of the expected type, that the caller has the right permissions on it, * and that the object has been initialized. * * This function is intended to be called on the kernel-side system * call handlers to validate kernel object pointers passed in from * userspace. * * @param obj Address of the kernel object * @param otype Expected type of the kernel object * @param init If true, this is for an init function and we will not error * out if the object is not initialized * @return 0 If the object is valid * -EBADF if not a valid object of the specified type * -EPERM If the caller does not have permissions * -EINVAL Object is not initialized */ int _k_object_validate(void *obj, enum k_objects otype, int init); /** * @brief Runtime expression check for system call arguments * * Used in handler functions to perform various runtime checks on arguments, * and generate a kernel oops if anything is not expected, printing a custom * message. * * @param expr Boolean expression to verify, a false result will trigger an * oops * @param ssf Syscall stack frame argument passed to the handler function * @param fmt Printf-style format string (followed by appropriate variadic * arguments) to print on verification failure */ #define _SYSCALL_VERIFY_MSG(expr, ssf, fmt, ...) \ do { \ if (!(expr)) { \ printk("FATAL: syscall %s failed check: " fmt "\n", \ __func__, ##__VA_ARGS__); \ _arch_syscall_oops(ssf); \ } \ } while (0) /** * @brief Runtime expression check for system call arguments * * Used in handler functions to perform various runtime checks on arguments, * and generate a kernel oops if anything is not expected. * * @param expr Boolean expression to verify, a false result will trigger an * oops. A stringified version of this expression will be printed. * @param ssf Syscall stack frame argument passed to the handler function * arguments) to print on verification failure */ #define _SYSCALL_VERIFY(expr, ssf) _SYSCALL_VERIFY_MSG(expr, ssf, #expr) #define _SYSCALL_MEMORY(ptr, size, write, ssf) \ _SYSCALL_VERIFY_MSG(!_arch_buffer_validate((void *)ptr, size, write), \ ssf, "Memory region %p (size %u) %s access denied", \ (void *)(ptr), (u32_t)(size), \ write ? "write" : "read") /** * @brief Runtime check that a user thread has read permission to a memory area * * Checks that the particular memory area is readable by the currently running * thread if the CPU was in user mode, and generates a kernel oops if it * wasn't. Prevents userspace from getting the kernel to read memory the thread * does not have access to, or passing in garbage pointers that would * crash/pagefault the kernel if dereferenced. * * @param ptr Memory area to examine * @param size Size of the memory area * @param write If the thread should be able to write to this memory, not just * read it * @param ssf Syscall stack frame argument passed to the handler function */ #define _SYSCALL_MEMORY_READ(ptr, size, ssf) \ _SYSCALL_MEMORY(ptr, size, 0, ssf) /** * @brief Runtime check that a user thread has write permission to a memory area * * Checks that the particular memory area is readable and writable by the * currently running thread if the CPU was in user mode, and generates a kernel * oops if it wasn't. Prevents userspace from getting the kernel to read or * modify memory the thread does not have access to, or passing in garbage * pointers that would crash/pagefault the kernel if dereferenced. * * @param ptr Memory area to examine * @param size Size of the memory area * @param write If the thread should be able to write to this memory, not just * read it * @param ssf Syscall stack frame argument passed to the handler function */ #define _SYSCALL_MEMORY_WRITE(ptr, size, ssf) \ _SYSCALL_MEMORY(ptr, size, 1, ssf) #define _SYSCALL_IS_OBJ(ptr, type, init, ssf) \ _SYSCALL_VERIFY_MSG(!_k_object_validate((void *)ptr, type, init), ssf, \ "object %p access denied", (void *)(ptr)) /** * @brief Runtime check kernel object pointer for non-init functions * * Calls _k_object_validate and triggers a kernel oops if the check files. * For use in system call handlers which are not init functions; a check * enforcing that an object is initialized* will not occur. * * @param ptr Untrusted kernel object pointer * @param type Expected kernel object type * @param ssf Syscall stack frame argument passed to the handler function */ #define _SYSCALL_OBJ(ptr, type, ssf) \ _SYSCALL_IS_OBJ(ptr, type, 0, ssf) /** * @brief Runtime check kernel object pointer for non-init functions * * See description of _SYSCALL_IS_OBJ. For use in system call handlers which * are not init functions; a check enforcing that an object is initialized * will not occur. * * @param ptr Untrusted kernel object pointer * @param type Expected kernel object type * @param ssf Syscall stack frame argument passed to the handler function */ #define _SYSCALL_OBJ_INIT(ptr, type, ssf) \ _SYSCALL_IS_OBJ(ptr, type, 1, ssf) /* Convenience macros for handler implementations */ #define _SYSCALL_ARG0 ARG_UNUSED(arg1); ARG_UNUSED(arg2); ARG_UNUSED(arg3); \ ARG_UNUSED(arg4); ARG_UNUSED(arg5); ARG_UNUSED(arg6) #define _SYSCALL_ARG1 ARG_UNUSED(arg2); ARG_UNUSED(arg3); ARG_UNUSED(arg4); \ ARG_UNUSED(arg5); ARG_UNUSED(arg6) #define _SYSCALL_ARG2 ARG_UNUSED(arg3); ARG_UNUSED(arg4); ARG_UNUSED(arg5); \ ARG_UNUSED(arg6) #define _SYSCALL_ARG3 ARG_UNUSED(arg4); ARG_UNUSED(arg5); ARG_UNUSED(arg6) #define _SYSCALL_ARG4 ARG_UNUSED(arg5); ARG_UNUSED(arg6) #define _SYSCALL_ARG5 ARG_UNUSED(arg6) #endif /* _ASMLANGUAGE */ #endif /* CONFIG_USERSPACE */ #endif /* _ZEPHYR_SYSCALL_H_ */