| // Copyright 2016 The Fuchsia Authors |
| // |
| // Use of this source code is governed by a MIT-style |
| // license that can be found in the LICENSE file or at |
| // https://opensource.org/licenses/MIT |
| |
| #ifndef ZIRCON_KERNEL_LIB_USER_COPY_INCLUDE_LIB_USER_COPY_INTERNAL_H_ |
| #define ZIRCON_KERNEL_LIB_USER_COPY_INCLUDE_LIB_USER_COPY_INTERNAL_H_ |
| |
| #include <stddef.h> |
| |
| #include <ktl/type_traits.h> |
| #include <sys/types.h> |
| |
| namespace internal { |
| |
| // Generates a type whose ::value is true if |T| is allowed to be copied to/from usermode. |
| // |
| // The purpose of this type trait is to ensure a stable ABI and prevent bugs by restricting the |
| // types that may be copied to/from usermode. These types must: |
| // |
| // * Be trivial and can be trivially copied. |
| // |
| // * Have a standard-layout, which ensures their layout won't change from compiler to compiler. |
| // |
| // * Have unique object representations, which ensures they do not contain implicit |
| // padding. Copying types with implicit padding can lead information disclosure bugs because the |
| // padding may or may not contain uninitialized data. |
| template <typename T> |
| struct is_copy_allowed |
| : ktl::disjunction<ktl::conjunction<ktl::is_trivial<T>, ktl::is_standard_layout<T>, |
| ktl::has_unique_object_representations<T>>> {}; |
| |
| // Confine a |vaddr, len| pair to [0, top]; if either vaddr or vaddr+len cross top, fills in {0,0} |
| void confine_user_address_range(vaddr_t* vaddr, size_t* len, const uintptr_t top); |
| |
| } // namespace internal |
| |
| #endif // ZIRCON_KERNEL_LIB_USER_COPY_INCLUDE_LIB_USER_COPY_INTERNAL_H_ |
