/*
* Copyright (C) 2007 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.
*/
#include "linker.h"
#include "linker_dlwarning.h"
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <android/api-level.h>
#include <bionic/pthread_internal.h>
#include "private/bionic_tls.h"
#include "private/ScopedPthreadMutexLocker.h"
#include "private/ThreadLocalBuffer.h"
/* This file hijacks the symbols stubbed out in libdl.so. */
static pthread_mutex_t g_dl_mutex = PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP;
static const char* __bionic_set_dlerror(char* new_value) {
char** dlerror_slot = &reinterpret_cast<char**>(__get_tls())[TLS_SLOT_DLERROR];
const char* old_value = *dlerror_slot;
*dlerror_slot = new_value;
return old_value;
}
static void __bionic_format_dlerror(const char* msg, const char* detail) {
char* buffer = __get_thread()->dlerror_buffer;
strlcpy(buffer, msg, __BIONIC_DLERROR_BUFFER_SIZE);
if (detail != nullptr) {
strlcat(buffer, ": ", __BIONIC_DLERROR_BUFFER_SIZE);
strlcat(buffer, detail, __BIONIC_DLERROR_BUFFER_SIZE);
}
__bionic_set_dlerror(buffer);
}
const char* dlerror() {
const char* old_value = __bionic_set_dlerror(nullptr);
return old_value;
}
void android_get_LD_LIBRARY_PATH(char* buffer, size_t buffer_size) {
ScopedPthreadMutexLocker locker(&g_dl_mutex);
do_android_get_LD_LIBRARY_PATH(buffer, buffer_size);
}
void android_update_LD_LIBRARY_PATH(const char* ld_library_path) {
ScopedPthreadMutexLocker locker(&g_dl_mutex);
do_android_update_LD_LIBRARY_PATH(ld_library_path);
}
static void* dlopen_ext(const char* filename, int flags,
const android_dlextinfo* extinfo, void* caller_addr) {
ScopedPthreadMutexLocker locker(&g_dl_mutex);
void* result = do_dlopen(filename, flags, extinfo, caller_addr);
if (result == nullptr) {
__bionic_format_dlerror("dlopen failed", linker_get_error_buffer());
return nullptr;
}
return result;
}
void* android_dlopen_ext(const char* filename, int flags, const android_dlextinfo* extinfo) {
void* caller_addr = __builtin_return_address(0);
return dlopen_ext(filename, flags, extinfo, caller_addr);
}
void* dlopen(const char* filename, int flags) {
void* caller_addr = __builtin_return_address(0);
return dlopen_ext(filename, flags, nullptr, caller_addr);
}
void* dlsym_impl(void* handle, const char* symbol, const char* version, void* caller_addr) {
ScopedPthreadMutexLocker locker(&g_dl_mutex);
void* result;
if (!do_dlsym(handle, symbol, version, caller_addr, &result)) {
__bionic_format_dlerror(linker_get_error_buffer(), nullptr);
return nullptr;
}
return result;
}
void* dlsym(void* handle, const char* symbol) {
void* caller_addr = __builtin_return_address(0);
return dlsym_impl(handle, symbol, nullptr, caller_addr);
}
void* dlvsym(void* handle, const char* symbol, const char* version) {
void* caller_addr = __builtin_return_address(0);
return dlsym_impl(handle, symbol, version, caller_addr);
}
int dladdr(const void* addr, Dl_info* info) {
ScopedPthreadMutexLocker locker(&g_dl_mutex);
return do_dladdr(addr, info);
}
int dlclose(void* handle) {
ScopedPthreadMutexLocker locker(&g_dl_mutex);
int result = do_dlclose(handle);
if (result != 0) {
__bionic_format_dlerror("dlclose failed", linker_get_error_buffer());
}
return result;
}
int dl_iterate_phdr(int (*cb)(dl_phdr_info* info, size_t size, void* data), void* data) {
ScopedPthreadMutexLocker locker(&g_dl_mutex);
return do_dl_iterate_phdr(cb, data);
}
void android_set_application_target_sdk_version(uint32_t target) {
// lock to avoid modification in the middle of dlopen.
ScopedPthreadMutexLocker locker(&g_dl_mutex);
set_application_target_sdk_version(target);
}
uint32_t android_get_application_target_sdk_version() {
return get_application_target_sdk_version();
}
void android_dlwarning(void* obj, void (*f)(void*, const char*)) {
ScopedPthreadMutexLocker locker(&g_dl_mutex);
get_dlwarning(obj, f);
}
bool android_init_namespaces(const char* public_ns_sonames,
const char* anon_ns_library_path) {
ScopedPthreadMutexLocker locker(&g_dl_mutex);
bool success = init_namespaces(public_ns_sonames, anon_ns_library_path);
if (!success) {
__bionic_format_dlerror("android_init_namespaces failed", linker_get_error_buffer());
}
return success;
}
android_namespace_t* android_create_namespace(const char* name,
const char* ld_library_path,
const char* default_library_path,
uint64_t type,
const char* permitted_when_isolated_path,
android_namespace_t* parent_namespace) {
void* caller_addr = __builtin_return_address(0);
ScopedPthreadMutexLocker locker(&g_dl_mutex);
android_namespace_t* result = create_namespace(caller_addr,
name,
ld_library_path,
default_library_path,
type,
permitted_when_isolated_path,
parent_namespace);
if (result == nullptr) {
__bionic_format_dlerror("android_create_namespace failed", linker_get_error_buffer());
}
return result;
}
// name_offset: starting index of the name in libdl_info.strtab
#define ELF32_SYM_INITIALIZER(name_offset, value, shndx) \
{ name_offset, \
reinterpret_cast<Elf32_Addr>(value), \
/* st_size */ 0, \
(shndx == 0) ? 0 : (STB_GLOBAL << 4), \
/* st_other */ 0, \
shndx, \
}
#define ELF64_SYM_INITIALIZER(name_offset, value, shndx) \
{ name_offset, \
(shndx == 0) ? 0 : (STB_GLOBAL << 4), \
/* st_other */ 0, \
shndx, \
reinterpret_cast<Elf64_Addr>(value), \
/* st_size */ 0, \
}
static const char ANDROID_LIBDL_STRTAB[] =
// 0000000 00011111 111112 22222222 2333333 3333444444444455555555556666666 6667777777777888888888899999 99999
// 0123456 78901234 567890 12345678 9012345 6789012345678901234567890123456 7890123456789012345678901234 56789
"dlopen\0dlclose\0dlsym\0dlerror\0dladdr\0android_update_LD_LIBRARY_PATH\0android_get_LD_LIBRARY_PATH\0dl_it"
// 00000000001 1111111112222222222 3333333333444444444455555555556666666666777 777777788888888889999999999
// 01234567890 1234567890123456789 0123456789012345678901234567890123456789012 345678901234567890123456789
"erate_phdr\0android_dlopen_ext\0android_set_application_target_sdk_version\0android_get_application_tar"
// 0000000000111111 111122222222223333333333 4444444444555555555566666 6666677 777777778888888888
// 0123456789012345 678901234567890123456789 0123456789012345678901234 5678901 234567890123456789
"get_sdk_version\0android_init_namespaces\0android_create_namespace\0dlvsym\0android_dlwarning\0"
#if defined(__arm__)
// 290
"dl_unwind_find_exidx\0"
#endif
;
static ElfW(Sym) g_libdl_symtab[] = {
// Total length of libdl_info.strtab, including trailing 0.
// This is actually the STH_UNDEF entry. Technically, it's
// supposed to have st_name == 0, but instead, it points to an index
// in the strtab with a \0 to make iterating through the symtab easier.
ELFW(SYM_INITIALIZER)(sizeof(ANDROID_LIBDL_STRTAB) - 1, nullptr, 0),
ELFW(SYM_INITIALIZER)( 0, &dlopen, 1),
ELFW(SYM_INITIALIZER)( 7, &dlclose, 1),
ELFW(SYM_INITIALIZER)( 15, &dlsym, 1),
ELFW(SYM_INITIALIZER)( 21, &dlerror, 1),
ELFW(SYM_INITIALIZER)( 29, &dladdr, 1),
ELFW(SYM_INITIALIZER)( 36, &android_update_LD_LIBRARY_PATH, 1),
ELFW(SYM_INITIALIZER)( 67, &android_get_LD_LIBRARY_PATH, 1),
ELFW(SYM_INITIALIZER)( 95, &dl_iterate_phdr, 1),
ELFW(SYM_INITIALIZER)(111, &android_dlopen_ext, 1),
ELFW(SYM_INITIALIZER)(130, &android_set_application_target_sdk_version, 1),
ELFW(SYM_INITIALIZER)(173, &android_get_application_target_sdk_version, 1),
ELFW(SYM_INITIALIZER)(216, &android_init_namespaces, 1),
ELFW(SYM_INITIALIZER)(240, &android_create_namespace, 1),
ELFW(SYM_INITIALIZER)(265, &dlvsym, 1),
ELFW(SYM_INITIALIZER)(272, &android_dlwarning, 1),
#if defined(__arm__)
ELFW(SYM_INITIALIZER)(290, &dl_unwind_find_exidx, 1),
#endif
};
// Fake out a hash table with a single bucket.
//
// A search of the hash table will look through g_libdl_symtab starting with index 1, then
// use g_libdl_chains to find the next index to look at. g_libdl_chains should be set up to
// walk through every element in g_libdl_symtab, and then end with 0 (sentinel value).
//
// That is, g_libdl_chains should look like { 0, 2, 3, ... N, 0 } where N is the number
// of actual symbols, or nelems(g_libdl_symtab)-1 (since the first element of g_libdl_symtab is not
// a real symbol). (See soinfo_elf_lookup().)
//
// Note that adding any new symbols here requires stubbing them out in libdl.
static unsigned g_libdl_buckets[1] = { 1 };
#if defined(__arm__)
static unsigned g_libdl_chains[] = { 0, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 0 };
#else
static unsigned g_libdl_chains[] = { 0, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 0 };
#endif
static uint8_t __libdl_info_buf[sizeof(soinfo)] __attribute__((aligned(8)));
static soinfo* __libdl_info = nullptr;
extern android_namespace_t g_default_namespace;
// This is used by the dynamic linker. Every process gets these symbols for free.
soinfo* get_libdl_info() {
if (__libdl_info == nullptr) {
__libdl_info = new (__libdl_info_buf) soinfo(&g_default_namespace, "libdl.so", nullptr, 0, RTLD_GLOBAL);
__libdl_info->flags_ |= FLAG_LINKED;
__libdl_info->strtab_ = ANDROID_LIBDL_STRTAB;
__libdl_info->symtab_ = g_libdl_symtab;
__libdl_info->nbucket_ = sizeof(g_libdl_buckets)/sizeof(unsigned);
__libdl_info->nchain_ = sizeof(g_libdl_chains)/sizeof(unsigned);
__libdl_info->bucket_ = g_libdl_buckets;
__libdl_info->chain_ = g_libdl_chains;
__libdl_info->ref_count_ = 1;
__libdl_info->strtab_size_ = sizeof(ANDROID_LIBDL_STRTAB);
__libdl_info->local_group_root_ = __libdl_info;
__libdl_info->soname_ = "libdl.so";
__libdl_info->target_sdk_version_ = __ANDROID_API__;
__libdl_info->generate_handle();
#if defined(__work_around_b_24465209__)
strlcpy(__libdl_info->old_name_, __libdl_info->soname_, sizeof(__libdl_info->old_name_));
#endif
}
return __libdl_info;
}