efbe9a5eef
Introduce a new flag ANDROID_DLEXT_RESERVED_ADDRESS_RECURSIVE which instructs the linker to use the reserved address space to load all of the newly-loaded libraries required by a dlopen() call instead of only the main library. They will be loaded consecutively into that region if they fit. The RELRO sections of all the loaded libraries will also be considered for reading/writing shared RELRO data. This will allow the WebView implementation to potentially consist of more than one .so file while still benefiting from the RELRO sharing optimisation, which would otherwise only apply to the "root" .so file. Test: bionic-unit-tests (existing and newly added) Bug: 110790153 Change-Id: I61da775c29fd5017d9a1e2b6b3757c3d20a355b3
190 lines
7 KiB
C
190 lines
7 KiB
C
/*
|
|
* Copyright (C) 2014 The Android Open Source Project
|
|
*
|
|
* Licensed under the Apache License, Version 2.0 (the "License");
|
|
* you may not use this file except in compliance with the License.
|
|
* You may obtain a copy of the License at
|
|
*
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS,
|
|
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
* See the License for the specific language governing permissions and
|
|
* limitations under the License.
|
|
*/
|
|
|
|
#ifndef __ANDROID_DLEXT_H__
|
|
#define __ANDROID_DLEXT_H__
|
|
|
|
#include <stdbool.h>
|
|
#include <stddef.h>
|
|
#include <stdint.h>
|
|
#include <sys/cdefs.h>
|
|
#include <sys/types.h> /* for off64_t */
|
|
|
|
/**
|
|
* @addtogroup libdl Dynamic Linker
|
|
* @{
|
|
*/
|
|
|
|
/**
|
|
* \file
|
|
* Advanced dynamic library opening support. Most users will want to use
|
|
* the standard [dlopen(3)](http://man7.org/linux/man-pages/man3/dlopen.3.html)
|
|
* functionality in `<dlfcn.h>` instead.
|
|
*/
|
|
|
|
__BEGIN_DECLS
|
|
|
|
/** Bitfield definitions for `android_dlextinfo::flags`. */
|
|
enum {
|
|
/**
|
|
* When set, the `reserved_addr` and `reserved_size` fields must point to an
|
|
* already-reserved region of address space which will be used to load the
|
|
* library if it fits.
|
|
*
|
|
* If the reserved region is not large enough, loading will fail.
|
|
*/
|
|
ANDROID_DLEXT_RESERVED_ADDRESS = 0x1,
|
|
|
|
/**
|
|
* Like `ANDROID_DLEXT_RESERVED_ADDRESS`, but if the reserved region is not large enough,
|
|
* the linker will choose an available address instead.
|
|
*/
|
|
ANDROID_DLEXT_RESERVED_ADDRESS_HINT = 0x2,
|
|
|
|
/**
|
|
* When set, write the GNU RELRO section of the mapped library to `relro_fd`
|
|
* after relocation has been performed, to allow it to be reused by another
|
|
* process loading the same library at the same address. This implies
|
|
* `ANDROID_DLEXT_USE_RELRO`.
|
|
*
|
|
* This is mainly useful for the system WebView implementation.
|
|
*/
|
|
ANDROID_DLEXT_WRITE_RELRO = 0x4,
|
|
|
|
/**
|
|
* When set, compare the GNU RELRO section of the mapped library to `relro_fd`
|
|
* after relocation has been performed, and replace any relocated pages that
|
|
* are identical with a version mapped from the file.
|
|
*
|
|
* This is mainly useful for the system WebView implementation.
|
|
*/
|
|
ANDROID_DLEXT_USE_RELRO = 0x8,
|
|
|
|
/**
|
|
* Use `library_fd` instead of opening the file by name.
|
|
* The filename parameter is still used to identify the library.
|
|
*/
|
|
ANDROID_DLEXT_USE_LIBRARY_FD = 0x10,
|
|
|
|
/**
|
|
* If opening a library using `library_fd` read it starting at `library_fd_offset`.
|
|
* This is mainly useful for loading a library stored within another file (such as uncompressed
|
|
* inside a ZIP archive).
|
|
* This flag is only valid when `ANDROID_DLEXT_USE_LIBRARY_FD` is set.
|
|
*/
|
|
ANDROID_DLEXT_USE_LIBRARY_FD_OFFSET = 0x20,
|
|
|
|
/**
|
|
* When set, do not use `stat(2)` to check if the library has already been loaded.
|
|
*
|
|
* This flag allows forced loading of the library in the case when for some
|
|
* reason multiple ELF files share the same filename (because the already-loaded
|
|
* library has been removed and overwritten, for example).
|
|
*
|
|
* Note that if the library has the same `DT_SONAME` as an old one and some other
|
|
* library has the soname in its `DT_NEEDED` list, the first one will be used to resolve any
|
|
* dependencies.
|
|
*/
|
|
ANDROID_DLEXT_FORCE_LOAD = 0x40,
|
|
|
|
// Historically we had two other options for ART.
|
|
// They were last available in Android P.
|
|
// Reuse these bits last!
|
|
// ANDROID_DLEXT_FORCE_FIXED_VADDR = 0x80
|
|
// ANDROID_DLEXT_LOAD_AT_FIXED_ADDRESS = 0x100
|
|
|
|
/**
|
|
* This flag used to load library in a different namespace. The namespace is
|
|
* specified in `library_namespace`.
|
|
*
|
|
* This flag is for internal use only (since there is no NDK API for namespaces).
|
|
*/
|
|
ANDROID_DLEXT_USE_NAMESPACE = 0x200,
|
|
|
|
/**
|
|
* Instructs dlopen to apply `ANDROID_DLEXT_RESERVED_ADDRESS`,
|
|
* `ANDROID_DLEXT_RESERVED_ADDRESS_HINT`, `ANDROID_DLEXT_WRITE_RELRO` and
|
|
* `ANDROID_DLEXT_USE_RELRO` to any libraries loaded as dependencies of the
|
|
* main library as well.
|
|
*
|
|
* This means that if the main library depends on one or more not-already-loaded libraries, they
|
|
* will be loaded consecutively into the region starting at `reserved_addr`, and `reserved_size`
|
|
* must be large enough to contain all of the libraries. The libraries will be loaded in the
|
|
* deterministic order constructed from the DT_NEEDED entries, rather than the more secure random
|
|
* order used by default.
|
|
*
|
|
* Each library's GNU RELRO sections will be written out to `relro_fd` in the same order they were
|
|
* loaded. This will mean that the resulting file is dependent on which of the libraries were
|
|
* already loaded, as only the newly loaded libraries will be included, not any already-loaded
|
|
* dependencies. The caller should ensure that the set of libraries newly loaded is consistent
|
|
* for this to be effective.
|
|
*
|
|
* This is mainly useful for the system WebView implementation.
|
|
*/
|
|
ANDROID_DLEXT_RESERVED_ADDRESS_RECURSIVE = 0x400,
|
|
|
|
|
|
/** Mask of valid bits. */
|
|
ANDROID_DLEXT_VALID_FLAG_BITS = ANDROID_DLEXT_RESERVED_ADDRESS |
|
|
ANDROID_DLEXT_RESERVED_ADDRESS_HINT |
|
|
ANDROID_DLEXT_WRITE_RELRO |
|
|
ANDROID_DLEXT_USE_RELRO |
|
|
ANDROID_DLEXT_USE_LIBRARY_FD |
|
|
ANDROID_DLEXT_USE_LIBRARY_FD_OFFSET |
|
|
ANDROID_DLEXT_FORCE_LOAD |
|
|
ANDROID_DLEXT_USE_NAMESPACE |
|
|
ANDROID_DLEXT_RESERVED_ADDRESS_RECURSIVE,
|
|
};
|
|
|
|
struct android_namespace_t;
|
|
|
|
/** Used to pass Android-specific arguments to `android_dlopen_ext`. */
|
|
typedef struct {
|
|
/** A bitmask of `ANDROID_DLEXT_` enum values. */
|
|
uint64_t flags;
|
|
|
|
/** Used by `ANDROID_DLEXT_RESERVED_ADDRESS` and `ANDROID_DLEXT_RESERVED_ADDRESS_HINT`. */
|
|
void* reserved_addr;
|
|
/** Used by `ANDROID_DLEXT_RESERVED_ADDRESS` and `ANDROID_DLEXT_RESERVED_ADDRESS_HINT`. */
|
|
size_t reserved_size;
|
|
|
|
/** Used by `ANDROID_DLEXT_WRITE_RELRO` and `ANDROID_DLEXT_USE_RELRO`. */
|
|
int relro_fd;
|
|
|
|
/** Used by `ANDROID_DLEXT_USE_LIBRARY_FD`. */
|
|
int library_fd;
|
|
/** Used by `ANDROID_DLEXT_USE_LIBRARY_FD_OFFSET` */
|
|
off64_t library_fd_offset;
|
|
|
|
/** Used by `ANDROID_DLEXT_USE_NAMESPACE`. */
|
|
struct android_namespace_t* library_namespace;
|
|
} android_dlextinfo;
|
|
|
|
/**
|
|
* Opens the given library. The `__filename` and `__flags` arguments are
|
|
* the same as for [dlopen(3)](http://man7.org/linux/man-pages/man3/dlopen.3.html),
|
|
* with the Android-specific flags supplied via the `flags` member of `__info`.
|
|
*
|
|
* Available since API level 21.
|
|
*/
|
|
void* android_dlopen_ext(const char* __filename, int __flags, const android_dlextinfo* __info)
|
|
__INTRODUCED_IN(21);
|
|
|
|
__END_DECLS
|
|
|
|
/** @} */
|
|
|
|
#endif
|