linker/dlfcn.cpp

/*
 * Copyright (C) 2007 The Android Open Source Project
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *  * Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *  * Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include "linker.h"
#include "linker_cfi.h"
#include "linker_globals.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"

#define __LINKER_PUBLIC__ __attribute__((visibility("default")))

extern "C" {

android_namespace_t* __loader_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,
                                                       const void* caller_addr) __LINKER_PUBLIC__;
void* __loader_android_dlopen_ext(const char* filename,
                           int flags,
                           const android_dlextinfo* extinfo,
                           const void* caller_addr) __LINKER_PUBLIC__;
void __loader_android_dlwarning(void* obj, void (*f)(void*, const char*)) __LINKER_PUBLIC__;
uint32_t __loader_android_get_application_target_sdk_version() __LINKER_PUBLIC__;
void __loader_android_get_LD_LIBRARY_PATH(char* buffer, size_t buffer_size) __LINKER_PUBLIC__;
android_namespace_t* __loader_android_get_exported_namespace(const char* name) __LINKER_PUBLIC__;
bool __loader_android_init_anonymous_namespace(const char* shared_libs_sonames,
                                               const char* library_search_path) __LINKER_PUBLIC__;
bool __loader_android_link_namespaces(android_namespace_t* namespace_from,
                                      android_namespace_t* namespace_to,
                                      const char* shared_libs_sonames) __LINKER_PUBLIC__;
void __loader_android_set_application_target_sdk_version(uint32_t target) __LINKER_PUBLIC__;
void __loader_android_update_LD_LIBRARY_PATH(const char* ld_library_path) __LINKER_PUBLIC__;
void __loader_cfi_fail(uint64_t CallSiteTypeId,
                       void* Ptr,
                       void *DiagData,
                       void *CallerPc) __LINKER_PUBLIC__;
int __loader_dl_iterate_phdr(int (*cb)(dl_phdr_info* info, size_t size, void* data),
                             void* data) __LINKER_PUBLIC__;
int __loader_dladdr(const void* addr, Dl_info* info) __LINKER_PUBLIC__;
int __loader_dlclose(void* handle) __LINKER_PUBLIC__;
char* __loader_dlerror() __LINKER_PUBLIC__;
void* __loader_dlopen(const char* filename, int flags, const void* caller_addr) __LINKER_PUBLIC__;
void* __loader_dlsym(void* handle, const char* symbol, const void* caller_addr) __LINKER_PUBLIC__;
void* __loader_dlvsym(void* handle,
                      const char* symbol,
                      const char* version,
                      const void* caller_addr) __LINKER_PUBLIC__;
#if defined(__arm__)
_Unwind_Ptr __loader_dl_unwind_find_exidx(_Unwind_Ptr pc, int* pcount) __LINKER_PUBLIC__;
#endif
}

static pthread_mutex_t g_dl_mutex = PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP;

static char* __bionic_set_dlerror(char* new_value) {
  char** dlerror_slot = &reinterpret_cast<char**>(__get_tls())[TLS_SLOT_DLERROR];

  char* old_value = *dlerror_slot;
  *dlerror_slot = new_value;
  if (new_value != nullptr) LD_LOG(kLogErrors, "dlerror set to \"%s\"", 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);
}

char* __loader_dlerror() {
  char* old_value = __bionic_set_dlerror(nullptr);
  return old_value;
}

void __loader_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 __loader_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,
                        const void* caller_addr) {
  ScopedPthreadMutexLocker locker(&g_dl_mutex);
  g_linker_logger.ResetState();
  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* __loader_android_dlopen_ext(const char* filename,
                           int flags,
                           const android_dlextinfo* extinfo,
                           const void* caller_addr) {
  return dlopen_ext(filename, flags, extinfo, caller_addr);
}

void* __loader_dlopen(const char* filename, int flags, const void* caller_addr) {
  return dlopen_ext(filename, flags, nullptr, caller_addr);
}

void* dlsym_impl(void* handle, const char* symbol, const char* version, const void* caller_addr) {
  ScopedPthreadMutexLocker locker(&g_dl_mutex);
  g_linker_logger.ResetState();
  void* result;
  if (!do_dlsym(handle, symbol, version, caller_addr, &result)) {
    __bionic_format_dlerror(linker_get_error_buffer(), nullptr);
    return nullptr;
  }

  return result;
}

void* __loader_dlsym(void* handle, const char* symbol, const void* caller_addr) {
  return dlsym_impl(handle, symbol, nullptr, caller_addr);
}

void* __loader_dlvsym(void* handle, const char* symbol, const char* version, const void* caller_addr) {
  return dlsym_impl(handle, symbol, version, caller_addr);
}

int __loader_dladdr(const void* addr, Dl_info* info) {
  ScopedPthreadMutexLocker locker(&g_dl_mutex);
  return do_dladdr(addr, info);
}

int __loader_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 __loader_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);
}

// This function is needed by libgcc.a
int dl_iterate_phdr(int (*cb)(dl_phdr_info* info, size_t size, void* data), void* data) {
  return __loader_dl_iterate_phdr(cb, data);
}

#if defined(__arm__)
_Unwind_Ptr __loader_dl_unwind_find_exidx(_Unwind_Ptr pc, int* pcount) {
  ScopedPthreadMutexLocker locker(&g_dl_mutex);
  return do_dl_unwind_find_exidx(pc, pcount);
}
#endif

void __loader_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 __loader_android_get_application_target_sdk_version() {
  return get_application_target_sdk_version();
}

void __loader_android_dlwarning(void* obj, void (*f)(void*, const char*)) {
  ScopedPthreadMutexLocker locker(&g_dl_mutex);
  get_dlwarning(obj, f);
}

bool __loader_android_init_anonymous_namespace(const char* shared_libs_sonames,
                                               const char* library_search_path) {
  ScopedPthreadMutexLocker locker(&g_dl_mutex);
  bool success = init_anonymous_namespace(shared_libs_sonames, library_search_path);
  if (!success) {
    __bionic_format_dlerror("android_init_anonymous_namespace failed", linker_get_error_buffer());
  }

  return success;
}

android_namespace_t* __loader_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,
                                                const void* caller_addr) {
  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;
}

bool __loader_android_link_namespaces(android_namespace_t* namespace_from,
                                      android_namespace_t* namespace_to,
                                      const char* shared_libs_sonames) {
  ScopedPthreadMutexLocker locker(&g_dl_mutex);

  bool success = link_namespaces(namespace_from, namespace_to, shared_libs_sonames);

  if (!success) {
    __bionic_format_dlerror("android_link_namespaces failed", linker_get_error_buffer());
  }

  return success;
}

android_namespace_t* __loader_android_get_exported_namespace(const char* name) {
  return get_exported_namespace(name);
}

void __loader_cfi_fail(uint64_t CallSiteTypeId, void* Ptr, void *DiagData, void *CallerPc) {
  CFIShadowWriter::CfiFail(CallSiteTypeId, Ptr, DiagData, CallerPc);
}

static uint8_t __libdl_info_buf[sizeof(soinfo)] __attribute__((aligned(8)));
static soinfo* __libdl_info = nullptr;

// This is used by the dynamic linker. Every process gets these symbols for free.
soinfo* get_libdl_info(const char* linker_path,
                       const soinfo& linker_si,
                       const link_map& linker_map) {
  CHECK((linker_si.flags_ & FLAG_GNU_HASH) != 0);

  if (__libdl_info == nullptr) {
    __libdl_info = new (__libdl_info_buf) soinfo(&g_default_namespace, linker_path, nullptr, 0, 0);
    __libdl_info->flags_ |= (FLAG_LINKED | FLAG_GNU_HASH);
    __libdl_info->strtab_ = linker_si.strtab_;
    __libdl_info->symtab_ = linker_si.symtab_;
    __libdl_info->load_bias = linker_si.load_bias;

    __libdl_info->gnu_nbucket_ = linker_si.gnu_nbucket_;
    __libdl_info->gnu_maskwords_ = linker_si.gnu_maskwords_;
    __libdl_info->gnu_shift2_ = linker_si.gnu_shift2_;
    __libdl_info->gnu_bloom_filter_ = linker_si.gnu_bloom_filter_;
    __libdl_info->gnu_bucket_ = linker_si.gnu_bucket_;
    __libdl_info->gnu_chain_ = linker_si.gnu_chain_;

    __libdl_info->ref_count_ = 1;
    __libdl_info->strtab_size_ = linker_si.strtab_size_;
    __libdl_info->local_group_root_ = __libdl_info;
    __libdl_info->soname_ = "ld-android.so";
    __libdl_info->target_sdk_version_ = __ANDROID_API__;
    __libdl_info->generate_handle();
    __libdl_info->link_map_head.l_addr = linker_map.l_addr;
    __libdl_info->link_map_head.l_name = linker_map.l_name;
    __libdl_info->link_map_head.l_ld = linker_map.l_ld;
#if defined(__work_around_b_24465209__)
    strlcpy(__libdl_info->old_name_, __libdl_info->soname_, sizeof(__libdl_info->old_name_));
#endif
  }

  return __libdl_info;
}