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android / platform / bionic / refs/heads/main / . / linker / linker.cpp
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<
/*
* Copyright (C) 2008 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 <android/api-level.h>
#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/auxv.h>
#include <sys/mman.h>
#include <sys/param.h>
#include <sys/vfs.h>
#include <unistd.h>
#include <iterator>
#include <new>
#include <string>
#include <unordered_map>
#include <vector>
#include <android-base/properties.h>
#include <android-base/scopeguard.h>
#include <async_safe/log.h>
#include <bionic/pthread_internal.h>
// Private C library headers.
#include "linker.h"
#include "linker_block_allocator.h"
#include "linker_cfi.h"
#include "linker_config.h"
#include "linker_gdb_support.h"
#include "linker_globals.h"
#include "linker_debug.h"
#include "linker_dlwarning.h"
#include "linker_main.h"
#include "linker_namespaces.h"
#include "linker_sleb128.h"
#include "linker_phdr.h"
#include "linker_relocate.h"
#include "linker_tls.h"
#include "linker_translate_path.h"
#include "linker_utils.h"
#include "android-base/macros.h"
#include "android-base/stringprintf.h"
#include "android-base/strings.h"
#include "private/bionic_asm_note.h"
#include "private/bionic_call_ifunc_resolver.h"
#include "private/bionic_globals.h"
#include "ziparchive/zip_archive.h"
static std::unordered_map<void*, size_t> g_dso_handle_counters;
static bool g_anonymous_namespace_set = false;
static android_namespace_t* g_anonymous_namespace = &g_default_namespace;
static std::unordered_map<std::string, android_namespace_t*> g_exported_namespaces;
static LinkerTypeAllocator<soinfo> g_soinfo_allocator;
static LinkerTypeAllocator<LinkedListEntry<soinfo>> g_soinfo_links_allocator;
static LinkerTypeAllocator<android_namespace_t> g_namespace_allocator;
static LinkerTypeAllocator<LinkedListEntry<android_namespace_t>> g_namespace_list_allocator;
static uint64_t g_module_load_counter = 0;
static uint64_t g_module_unload_counter = 0;
static const char* const kLdConfigArchFilePath = "/system/etc/ld.config." ABI_STRING ".txt";
static const char* const kLdConfigFilePath = "/system/etc/ld.config.txt";
static const char* const kLdConfigVndkLiteFilePath = "/system/etc/ld.config.vndk_lite.txt";
static const char* const kLdGeneratedConfigFilePath = "/linkerconfig/ld.config.txt";
#if defined(__LP64__)
static const char* const kSystemLibDir = "/system/lib64";
static const char* const kOdmLibDir = "/odm/lib64";
static const char* const kVendorLibDir = "/vendor/lib64";
static const char* const kAsanSystemLibDir = "/data/asan/system/lib64";
static const char* const kAsanOdmLibDir = "/data/asan/odm/lib64";
static const char* const kAsanVendorLibDir = "/data/asan/vendor/lib64";
#else
static const char* const kSystemLibDir = "/system/lib";
static const char* const kOdmLibDir = "/odm/lib";
static const char* const kVendorLibDir = "/vendor/lib";
static const char* const kAsanSystemLibDir = "/data/asan/system/lib";
static const char* const kAsanOdmLibDir = "/data/asan/odm/lib";
static const char* const kAsanVendorLibDir = "/data/asan/vendor/lib";
#endif
static const char* const kAsanLibDirPrefix = "/data/asan";
static const char* const kDefaultLdPaths[] = {
kSystemLibDir,
kOdmLibDir,
kVendorLibDir,
nullptr
};
static const char* const kAsanDefaultLdPaths[] = {
kAsanSystemLibDir,
kSystemLibDir,
kAsanOdmLibDir,
kOdmLibDir,
kAsanVendorLibDir,
kVendorLibDir,
nullptr
};
#if defined(__aarch64__)
static const char* const kHwasanSystemLibDir = "/system/lib64/hwasan";
static const char* const kHwasanOdmLibDir = "/odm/lib64/hwasan";
static const char* const kHwasanVendorLibDir = "/vendor/lib64/hwasan";
// HWASan is only supported on aarch64.
static const char* const kHwsanDefaultLdPaths[] = {
kHwasanSystemLibDir,
kSystemLibDir,
kHwasanOdmLibDir,
kOdmLibDir,
kHwasanVendorLibDir,
kVendorLibDir,
nullptr
};
// Is HWASAN enabled?
static bool g_is_hwasan = false;
#else
static const char* const kHwsanDefaultLdPaths[] = {
kSystemLibDir,
kOdmLibDir,
kVendorLibDir,
nullptr
};
// Never any HWASan. Help the compiler remove the code we don't need.
constexpr bool g_is_hwasan = false;
#endif
// Is ASAN enabled?
static bool g_is_asan = false;
static CFIShadowWriter g_cfi_shadow;
CFIShadowWriter* get_cfi_shadow() {
return &g_cfi_shadow;
}
static bool is_system_library(const std::string& realpath) {
for (const auto& dir : g_default_namespace.get_default_library_paths()) {
if (file_is_in_dir(realpath, dir)) {
return true;
}
}
return false;
}
// Checks if the file exists and not a directory.
static bool file_exists(const char* path) {
struct stat s;
if (stat(path, &s) != 0) {
return false;
}
return S_ISREG(s.st_mode);
}
static std::string resolve_soname(const std::string& name) {
// We assume that soname equals to basename here
// TODO(dimitry): consider having honest absolute-path -> soname resolution
// note that since we might end up refusing to load this library because
// it is not in shared libs list we need to get the soname without actually loading
// the library.
//
// On the other hand there are several places where we already assume that
// soname == basename in particular for any not-loaded library mentioned
// in DT_NEEDED list.
return basename(name.c_str());
}
static bool maybe_accessible_via_namespace_links(android_namespace_t* ns, const char* name) {
std::string soname = resolve_soname(name);
for (auto& ns_link : ns->linked_namespaces()) {
if (ns_link.is_accessible(soname.c_str())) {
return true;
}
}
return false;
}
// TODO(dimitry): The exempt-list is a workaround for http://b/26394120 ---
// gradually remove libraries from this list until it is gone.
static bool is_exempt_lib(android_namespace_t* ns, const char* name, const soinfo* needed_by) {
static const char* const kLibraryExemptList[] = {
"libandroid_runtime.so",
"libbinder.so",
"libcrypto.so",
"libcutils.so",
"libexpat.so",
"libgui.so",
"libmedia.so",
"libnativehelper.so",
"libssl.so",
"libstagefright.so",
"libsqlite.so",
"libui.so",
"libutils.so",
nullptr
};
// If you're targeting N, you don't get the exempt-list.
if (get_application_target_sdk_version() >= 24) {
return false;
}
// if the library needed by a system library - implicitly assume it
// is exempt unless it is in the list of shared libraries for one or
// more linked namespaces
if (needed_by != nullptr && is_system_library(needed_by->get_realpath())) {
return !maybe_accessible_via_namespace_links(ns, name);
}
// if this is an absolute path - make sure it points to /system/lib(64)
if (name[0] == '/' && dirname(name) == kSystemLibDir) {
// and reduce the path to basename
name = basename(name);
}
for (size_t i = 0; kLibraryExemptList[i] != nullptr; ++i) {
if (strcmp(name, kLibraryExemptList[i]) == 0) {
return true;
}
}
return false;
}
// END OF WORKAROUND
static std::vector<std::string> g_ld_preload_names;
static void notify_gdb_of_load(soinfo* info) {
if (info->is_linker() || info->is_main_executable()) {
// gdb already knows about the linker and the main executable.
return;
}
link_map* map = &(info->link_map_head);
map->l_addr = info->load_bias;
// link_map l_name field is not const.
map->l_name = const_cast<char*>(info->get_realpath());
map->l_ld = info->dynamic;
CHECK(map->l_name != nullptr);
CHECK(map->l_name[0] != '\0');
notify_gdb_of_load(map);
}
static void notify_gdb_of_unload(soinfo* info) {
notify_gdb_of_unload(&(info->link_map_head));
}
LinkedListEntry<soinfo>* SoinfoListAllocator::alloc() {
return g_soinfo_links_allocator.alloc();
}
void SoinfoListAllocator::free(LinkedListEntry<soinfo>* entry) {
g_soinfo_links_allocator.free(entry);
}
LinkedListEntry<android_namespace_t>* NamespaceListAllocator::alloc() {
return g_namespace_list_allocator.alloc();
}
void NamespaceListAllocator::free(LinkedListEntry<android_namespace_t>* entry) {
g_namespace_list_allocator.free(entry);
}
soinfo* soinfo_alloc(android_namespace_t* ns, const char* name,
const struct stat* file_stat, off64_t file_offset,
uint32_t rtld_flags) {
if (strlen(name) >= PATH_MAX) {
async_safe_fatal("library name \"%s\" too long", name);
}
LD_DEBUG(any, "name %s: allocating soinfo for ns=%p", name, ns);
soinfo* si = new (g_soinfo_allocator.alloc()) soinfo(ns, name, file_stat,
file_offset, rtld_flags);
solist_add_soinfo(si);
si->generate_handle();
ns->add_soinfo(si);
LD_DEBUG(any, "name %s: allocated soinfo @ %p", name, si);
return si;
}
static void soinfo_free(soinfo* si) {
if (si == nullptr) {
return;
}
if (si->base != 0 && si->size != 0) {
if (!si->is_mapped_by_caller()) {
munmap(reinterpret_cast<void*>(si->base), si->size);
} else {
// remap the region as PROT_NONE, MAP_ANONYMOUS | MAP_NORESERVE
mmap(reinterpret_cast<void*>(si->base), si->size, PROT_NONE,
MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE, -1, 0);
}
}
if (si->has_min_version(6) && si->get_gap_size()) {
munmap(reinterpret_cast<void*>(si->get_gap_start()), si->get_gap_size());
}
LD_DEBUG(any, "name %s: freeing soinfo @ %p", si->get_realpath(), si);
if (!solist_remove_soinfo(si)) {
async_safe_fatal("soinfo=%p is not in soinfo_list (double unload?)", si);
}
// clear links to/from si
si->remove_all_links();
si->~soinfo();
g_soinfo_allocator.free(si);
}
static void parse_path(const char* path, const char* delimiters,
std::vector<std::string>* resolved_paths) {
std::vector<std::string> paths;
split_path(path, delimiters, &paths);
resolve_paths(paths, resolved_paths);
}
static void parse_LD_LIBRARY_PATH(const char* path) {
std::vector<std::string> ld_libary_paths;
parse_path(path, ":", &ld_libary_paths);
g_default_namespace.set_ld_library_paths(std::move(ld_libary_paths));
}
static bool realpath_fd(int fd, std::string* realpath) {
// proc_self_fd needs to be large enough to hold "/proc/self/fd/" plus an
// integer, plus the NULL terminator.
char proc_self_fd[32];
// We want to statically allocate this large buffer so that we don't grow
// the stack by too much.
static char buf[PATH_MAX];
async_safe_format_buffer(proc_self_fd, sizeof(proc_self_fd), "/proc/self/fd/%d", fd);
auto length = readlink(proc_self_fd, buf, sizeof(buf));
if (length == -1) {
if (!is_first_stage_init()) {
DL_WARN("readlink(\"%s\" [fd=%d]) failed: %m", proc_self_fd, fd);
}
return false;
}
realpath->assign(buf, length);
return true;
}
// Returns the address of the current thread's copy of a TLS module. If the current thread doesn't
// have a copy yet, allocate one on-demand if should_alloc is true, and return nullptr otherwise.
static inline void* get_tls_block_for_this_thread(const soinfo_tls* si_tls, bool should_alloc) {
const TlsModule& tls_mod = get_tls_module(si_tls->module_id);
if (tls_mod.static_offset != SIZE_MAX) {
const StaticTlsLayout& layout = __libc_shared_globals()->static_tls_layout;
char* static_tls = reinterpret_cast<char*>(__get_bionic_tcb()) - layout.offset_bionic_tcb();
return static_tls + tls_mod.static_offset;
} else if (should_alloc) {
const TlsIndex ti { si_tls->module_id, static_cast<size_t>(0 - TLS_DTV_OFFSET) };
return TLS_GET_ADDR(&ti);
} else {
TlsDtv* dtv = __get_tcb_dtv(__get_bionic_tcb());
if (dtv->generation < tls_mod.first_generation) return nullptr;
return dtv->modules[__tls_module_id_to_idx(si_tls->module_id)];
}
}
#if defined(__arm__)
// For a given PC, find the .so that it belongs to.
// Returns the base address of the .ARM.exidx section
// for that .so, and the number of 8-byte entries
// in that section (via *pcount).
//
// Intended to be called by libc's __gnu_Unwind_Find_exidx().
_Unwind_Ptr do_dl_unwind_find_exidx(_Unwind_Ptr pc, int* pcount) {
if (soinfo* si = find_containing_library(reinterpret_cast<void*>(pc))) {
*pcount = si->ARM_exidx_count;
return reinterpret_cast<_Unwind_Ptr>(si->ARM_exidx);
}
*pcount = 0;
return 0;
}
#endif
// Here, we only have to provide a callback to iterate across all the
// loaded libraries. gcc_eh does the rest.
int do_dl_iterate_phdr(int (*cb)(dl_phdr_info* info, size_t size, void* data), void* data) {
int rv = 0;
for (soinfo* si = solist_get_head(); si != nullptr; si = si->next) {
dl_phdr_info dl_info;
dl_info.dlpi_addr = si->link_map_head.l_addr;
dl_info.dlpi_name = si->link_map_head.l_name;
dl_info.dlpi_phdr = si->phdr;
dl_info.dlpi_phnum = si->phnum;
dl_info.dlpi_adds = g_module_load_counter;
dl_info.dlpi_subs = g_module_unload_counter;
if (soinfo_tls* tls_module = si->get_tls()) {
dl_info.dlpi_tls_modid = tls_module->module_id;
dl_info.dlpi_tls_data = get_tls_block_for_this_thread(tls_module, /*should_alloc=*/false);
} else {
dl_info.dlpi_tls_modid = 0;
dl_info.dlpi_tls_data = nullptr;
}
rv = cb(&dl_info, sizeof(dl_phdr_info), data);
if (rv != 0) {
break;
}
}
return rv;
}
ProtectedDataGuard::ProtectedDataGuard() {
if (ref_count_++ == 0) {
protect_data(PROT_READ | PROT_WRITE);
}
if (ref_count_ == 0) { // overflow
async_safe_fatal("Too many nested calls to dlopen()");
}
}
ProtectedDataGuard::~ProtectedDataGuard() {
if (--ref_count_ == 0) {
protect_data(PROT_READ);
}
}
void ProtectedDataGuard::protect_data(int protection) {
g_soinfo_allocator.protect_all(protection);
g_soinfo_links_allocator.protect_all(protection);
g_namespace_allocator.protect_all(protection);
g_namespace_list_allocator.protect_all(protection);
}
size_t ProtectedDataGuard::ref_count_ = 0;
// Each size has it's own allocator.
template<size_t size>
class SizeBasedAllocator {
public:
static void* alloc() {
return allocator_.alloc();
}
static void free(void* ptr) {
allocator_.free(ptr);
}
static void purge() {
allocator_.purge();
}
private:
static LinkerBlockAllocator allocator_;
};
template<size_t size>
LinkerBlockAllocator SizeBasedAllocator<size>::allocator_(size);
template<typename T>
class TypeBasedAllocator {
public:
static T* alloc() {
return reinterpret_cast<T*>(SizeBasedAllocator<sizeof(T)>::alloc());
}
static void free(T* ptr) {
SizeBasedAllocator<sizeof(T)>::free(ptr);
}
static void purge() {
SizeBasedAllocator<sizeof(T)>::purge();
}
};
class LoadTask {
public:
struct deleter_t {
void operator()(LoadTask* t) {
t->~LoadTask();
TypeBasedAllocator<LoadTask>::free(t);
}
};
static deleter_t deleter;
// needed_by is NULL iff dlopen is called from memory that isn't part of any known soinfo.
static LoadTask* create(const char* _Nonnull name, soinfo* _Nullable needed_by,
android_namespace_t* _Nonnull start_from,
std::unordered_map<const soinfo*, ElfReader>* _Nonnull readers_map) {
LoadTask* ptr = TypeBasedAllocator<LoadTask>::alloc();
return new (ptr) LoadTask(name, needed_by, start_from, readers_map);
}
const char* get_name() const {
return name_;
}
soinfo* get_needed_by() const {
return needed_by_;
}
soinfo* get_soinfo() const {
return si_;
}
void set_soinfo(soinfo* si) {
si_ = si;
}
off64_t get_file_offset() const {
return file_offset_;
}
void set_file_offset(off64_t offset) {
file_offset_ = offset;
}
int get_fd() const {
return fd_;
}
void set_fd(int fd, bool assume_ownership) {
if (fd_ != -1 && close_fd_) {
close(fd_);
}
fd_ = fd;
close_fd_ = assume_ownership;
}
const android_dlextinfo* get_extinfo() const {
return extinfo_;
}
void set_extinfo(const android_dlextinfo* extinfo) {
extinfo_ = extinfo;
}
bool is_dt_needed() const {
return is_dt_needed_;
}
void set_dt_needed(bool is_dt_needed) {
is_dt_needed_ = is_dt_needed;
}
// returns the namespace from where we need to start loading this.
const android_namespace_t* get_start_from() const {
return start_from_;
}
void remove_cached_elf_reader() {
CHECK(si_ != nullptr);
(*elf_readers_map_).erase(si_);
}
const ElfReader& get_elf_reader() const {
CHECK(si_ != nullptr);
return (*elf_readers_map_)[si_];
}
ElfReader& get_elf_reader() {
CHECK(si_ != nullptr);
return (*elf_readers_map_)[si_];
}
std::unordered_map<const soinfo*, ElfReader>* get_readers_map() {
return elf_readers_map_;
}
bool read(const char* realpath, off64_t file_size) {
ElfReader& elf_reader = get_elf_reader();
return elf_reader.Read(realpath, fd_, file_offset_, file_size);
}
bool load(address_space_params* address_space) {
ElfReader& elf_reader = get_elf_reader();
if (!elf_reader.Load(address_space)) {
return false;
}
si_->base = elf_reader.load_start();
si_->size = elf_reader.load_size();
si_->set_mapped_by_caller(elf_reader.is_mapped_by_caller());
si_->load_bias = elf_reader.load_bias();
si_->phnum = elf_reader.phdr_count();
si_->phdr = elf_reader.loaded_phdr();
si_->set_gap_start(elf_reader.gap_start());
si_->set_gap_size(elf_reader.gap_size());
si_->set_should_pad_segments(elf_reader.should_pad_segments());
si_->set_should_use_16kib_app_compat(elf_reader.should_use_16kib_app_compat());
if (si_->should_use_16kib_app_compat()) {
si_->set_compat_relro_start(elf_reader.compat_relro_start());
si_->set_compat_relro_size(elf_reader.compat_relro_size());
}
return true;
}
private:
LoadTask(const char* name,
soinfo* needed_by,
android_namespace_t* start_from,
std::unordered_map<const soinfo*, ElfReader>* readers_map)
: name_(name), needed_by_(needed_by), si_(nullptr),
fd_(-1), close_fd_(false), file_offset_(0), elf_readers_map_(readers_map),
is_dt_needed_(false), start_from_(start_from) {}
~LoadTask() {
if (fd_ != -1 && close_fd_) {
close(fd_);
}
}
const char* name_;
soinfo* needed_by_;
soinfo* si_;
const android_dlextinfo* extinfo_;
int fd_;
bool close_fd_;
off64_t file_offset_;
std::unordered_map<const soinfo*, ElfReader>* elf_readers_map_;
// TODO(dimitry): needed by workaround for http://b/26394120 (the exempt-list)
bool is_dt_needed_;
// END OF WORKAROUND
const android_namespace_t* const start_from_;
DISALLOW_IMPLICIT_CONSTRUCTORS(LoadTask);
};
LoadTask::deleter_t LoadTask::deleter;
template <typename T>
using linked_list_t = LinkedList<T, TypeBasedAllocator<LinkedListEntry<T>>>;
typedef linked_list_t<soinfo> SoinfoLinkedList;
typedef linked_list_t<const char> StringLinkedList;
typedef std::vector<LoadTask*> LoadTaskList;
enum walk_action_result_t : uint32_t {
kWalkStop = 0,
kWalkContinue = 1,
kWalkSkip = 2
};
// This function walks down the tree of soinfo dependencies
// in breadth-first order and
// * calls action(soinfo* si) for each node, and
// * terminates walk if action returns kWalkStop
// * skips children of the node if action
// return kWalkSkip
//
// walk_dependencies_tree returns false if walk was terminated
// by the action and true otherwise.
template<typename F>
static bool walk_dependencies_tree(soinfo* root_soinfo, F action) {
SoinfoLinkedList visit_list;
SoinfoLinkedList visited;
visit_list.push_back(root_soinfo);
soinfo* si;
while ((si = visit_list.pop_front()) != nullptr) {
if (visited.contains(si)) {
continue;
}
walk_action_result_t result = action(si);
if (result == kWalkStop) {
return false;
}
visited.push_back(si);
if (result != kWalkSkip) {
si->get_children().for_each([&](soinfo* child) {
visit_list.push_back(child);
});
}
}
return true;
}
static const ElfW(Sym)* dlsym_handle_lookup_impl(android_namespace_t* ns,
soinfo* root,
soinfo* skip_until,
soinfo** found,
SymbolName& symbol_name,
const version_info* vi) {
const ElfW(Sym)* result = nullptr;
bool skip_lookup = skip_until != nullptr;
walk_dependencies_tree(root, [&](soinfo* current_soinfo) {
if (skip_lookup) {
skip_lookup = current_soinfo != skip_until;
return kWalkContinue;
}
if (!ns->is_accessible(current_soinfo)) {
return kWalkSkip;
}
result = current_soinfo->find_symbol_by_name(symbol_name, vi);
if (result != nullptr) {
*found = current_soinfo;
return kWalkStop;
}
return kWalkContinue;
});
return result;
}
/* This is used by dlsym(3) to performs a global symbol lookup. If the
start value is null (for RTLD_DEFAULT), the search starts at the
beginning of the global solist. Otherwise the search starts at the
specified soinfo (for RTLD_NEXT).
*/
static const ElfW(Sym)* dlsym_linear_lookup(android_namespace_t* ns,
const char* name,
const version_info* vi,
soinfo** found,
soinfo* caller,
void* handle) {
SymbolName symbol_name(name);
auto& soinfo_list = ns->soinfo_list();
auto start = soinfo_list.begin();
if (handle == RTLD_NEXT) {
if (caller == nullptr) {
return nullptr;
} else {
auto it = soinfo_list.find(caller);
CHECK (it != soinfo_list.end());
start = ++it;
}
}
const ElfW(Sym)* s = nullptr;
for (auto it = start, end = soinfo_list.end(); it != end; ++it) {
soinfo* si = *it;
// Do not skip RTLD_LOCAL libraries in dlsym(RTLD_DEFAULT, ...)
// if the library is opened by application with target api level < M.
// See http://b/21565766
if ((si->get_rtld_flags() & RTLD_GLOBAL) == 0 && si->get_target_sdk_version() >= 23) {
continue;
}
s = si->find_symbol_by_name(symbol_name, vi);
if (s != nullptr) {
*found = si;
break;
}
}
// If not found - use dlsym_handle_lookup_impl for caller's local_group
if (s == nullptr && caller != nullptr) {
soinfo* local_group_root = caller->get_local_group_root();
return dlsym_handle_lookup_impl(local_group_root->get_primary_namespace(),
local_group_root,
(handle == RTLD_NEXT) ? caller : nullptr,
found,
symbol_name,
vi);
}
if (s != nullptr) {
LD_DEBUG(lookup, "%s s->st_value = %p, found->base = %p",
name, reinterpret_cast<void*>(s->st_value), reinterpret_cast<void*>((*found)->base));
}
return s;
}
// This is used by dlsym(3). It performs symbol lookup only within the
// specified soinfo object and its dependencies in breadth first order.
static const ElfW(Sym)* dlsym_handle_lookup(soinfo* si,
soinfo** found,
const char* name,
const version_info* vi) {
// According to man dlopen(3) and posix docs in the case when si is handle
// of the main executable we need to search not only in the executable and its
// dependencies but also in all libraries loaded with RTLD_GLOBAL.
//
// Since RTLD_GLOBAL is always set for the main executable and all dt_needed shared
// libraries and they are loaded in breath-first (correct) order we can just execute
// dlsym(RTLD_DEFAULT, ...); instead of doing two stage lookup.
if (si == solist_get_somain()) {
return dlsym_linear_lookup(&g_default_namespace, name, vi, found, nullptr, RTLD_DEFAULT);
}
SymbolName symbol_name(name);
// note that the namespace is not the namespace associated with caller_addr
// we use ns associated with root si intentionally here. Using caller_ns
// causes problems when user uses dlopen_ext to open a library in the separate
// namespace and then calls dlsym() on the handle.
return dlsym_handle_lookup_impl(si->get_primary_namespace(), si, nullptr, found, symbol_name, vi);
}
soinfo* find_containing_library(const void* p) {
// Addresses within a library may be tagged if they point to globals. Untag
// them so that the bounds check succeeds.
ElfW(Addr) address = reinterpret_cast<ElfW(Addr)>(untag_address(p));
for (soinfo* si = solist_get_head(); si != nullptr; si = si->next) {
if (address < si->base || address - si->base >= si->size) {
continue;
}
ElfW(Addr) vaddr = address - si->load_bias;
for (size_t i = 0; i != si->phnum; ++i) {
const ElfW(Phdr)* phdr = &si->phdr[i];
if (phdr->p_type != PT_LOAD) {
continue;
}
if (vaddr >= phdr->p_vaddr && vaddr < phdr->p_vaddr + phdr->p_memsz) {
return si;
}
}
}
return nullptr;
}
class ZipArchiveCache {
public:
ZipArchiveCache() {}
~ZipArchiveCache();
bool get_or_open(const char* zip_path, ZipArchiveHandle* handle);
private:
DISALLOW_COPY_AND_ASSIGN(ZipArchiveCache);
std::unordered_map<std::string, ZipArchiveHandle> cache_;
};
bool ZipArchiveCache::get_or_open(const char* zip_path, ZipArchiveHandle* handle) {
std::string key(zip_path);
auto it = cache_.find(key);
if (it != cache_.end()) {
*handle = it->second;
return true;
}
int fd = TEMP_FAILURE_RETRY(open(zip_path, O_RDONLY | O_CLOEXEC));
if (fd == -1) {
return false;
}
if (OpenArchiveFd(fd, "", handle) != 0) {
// invalid zip-file (?)
CloseArchive(*handle);
return false;
}
cache_[key] = *handle;
return true;
}
ZipArchiveCache::~ZipArchiveCache() {
for (const auto& it : cache_) {
CloseArchive(it.second);
}
}
static int open_library_in_zipfile(ZipArchiveCache* zip_archive_cache,
const char* const input_path,
off64_t* file_offset, std::string* realpath) {
std::string normalized_path;
if (!normalize_path(input_path, &normalized_path)) {
return -1;
}
const char* const path = normalized_path.c_str();
LD_DEBUG(any, "Trying zip file open from path \"%s\" -> normalized \"%s\"", input_path, path);
// Treat an '!/' separator inside a path as the separator between the name
// of the zip file on disk and the subdirectory to search within it.
// For example, if path is "foo.zip!/bar/bas/x.so", then we search for
// "bar/bas/x.so" within "foo.zip".
const char* const separator = strstr(path, kZipFileSeparator);
if (separator == nullptr) {
return -1;
}
char buf[512];
if (strlcpy(buf, path, sizeof(buf)) >= sizeof(buf)) {
DL_WARN("ignoring very long library path: %s", path);
return -1;
}
buf[separator - path] = '\0';
const char* zip_path = buf;
const char* file_path = &buf[separator - path + 2];
int fd = TEMP_FAILURE_RETRY(open(zip_path, O_RDONLY | O_CLOEXEC));
if (fd == -1) {
return -1;
}
ZipArchiveHandle handle;
if (!zip_archive_cache->get_or_open(zip_path, &handle)) {
// invalid zip-file (?)
close(fd);
return -1;
}
ZipEntry entry;
if (FindEntry(handle, file_path, &entry) != 0) {
// Entry was not found.
close(fd);
return -1;
}
// Check if it is properly stored
if (entry.method != kCompressStored || (entry.offset % page_size()) != 0) {
close(fd);
return -1;
}
*file_offset = entry.offset;
if (realpath_fd(fd, realpath)) {
*realpath += separator;
} else {
if (!is_first_stage_init()) {
DL_WARN("unable to get realpath for the library \"%s\". Will use given path.",
normalized_path.c_str());
}
*realpath = normalized_path;
}
return fd;
}
static bool format_path(char* buf, size_t buf_size, const char* path, const char* name) {
int n = async_safe_format_buffer(buf, buf_size, "%s/%s", path, name);
if (n < 0 || n >= static_cast<int>(buf_size)) {
DL_WARN("ignoring very long library path: %s/%s", path, name);
return false;
}
return true;
}
static int open_library_at_path(ZipArchiveCache* zip_archive_cache,
const char* path, off64_t* file_offset,
std::string* realpath) {
int fd = -1;
if (strstr(path, kZipFileSeparator) != nullptr) {
fd = open_library_in_zipfile(zip_archive_cache, path, file_offset, realpath);
}
if (fd == -1) {
fd = TEMP_FAILURE_RETRY(open(path, O_RDONLY | O_CLOEXEC));
if (fd != -1) {
*file_offset = 0;
if (!realpath_fd(fd, realpath)) {
if (!is_first_stage_init()) {
DL_WARN("unable to get realpath for the library \"%s\". Will use given path.", path);
}
*realpath = path;
}
}
}
return fd;
}
static int open_library_on_paths(ZipArchiveCache* zip_archive_cache,
const char* name, off64_t* file_offset,
const std::vector<std::string>& paths,
std::string* realpath) {
for (const auto& path : paths) {
char buf[512];
if (!format_path(buf, sizeof(buf), path.c_str(), name)) {
continue;
}
int fd = open_library_at_path(zip_archive_cache, buf, file_offset, realpath);
if (fd != -1) {
return fd;
}
}
return -1;
}
static int open_library(android_namespace_t* ns,
ZipArchiveCache* zip_archive_cache,
const char* name, soinfo *needed_by,
off64_t* file_offset, std::string* realpath) {
LD_DEBUG(any, "[ opening %s from namespace %s ]", name, ns->get_name());
// If the name contains a slash, we should attempt to open it directly and not search the paths.
if (strchr(name, '/') != nullptr) {
return open_library_at_path(zip_archive_cache, name, file_offset, realpath);
}
// LD_LIBRARY_PATH has the highest priority. We don't have to check accessibility when searching
// the namespace's path lists, because anything found on a namespace path list should always be
// accessible.
int fd = open_library_on_paths(zip_archive_cache, name, file_offset, ns->get_ld_library_paths(), realpath);
// Try the DT_RUNPATH, and verify that the library is accessible.
if (fd == -1 && needed_by != nullptr) {
fd = open_library_on_paths(zip_archive_cache, name, file_offset, needed_by->get_dt_runpath(), realpath);
if (fd != -1 && !ns->is_accessible(*realpath)) {
close(fd);
fd = -1;
}
}
// Finally search the namespace's main search path list.
if (fd == -1) {
fd = open_library_on_paths(zip_archive_cache, name, file_offset, ns->get_default_library_paths(), realpath);
}
return fd;
}
int open_executable(const char* path, off64_t* file_offset, std::string* realpath) {
ZipArchiveCache zip_archive_cache;
return open_library_at_path(&zip_archive_cache, path, file_offset, realpath);
}
const char* fix_dt_needed(const char* dt_needed, const char* sopath __unused) {
#if !defined(__LP64__)
// Work around incorrect DT_NEEDED entries for old apps: http://b/21364029
int app_target_api_level = get_application_target_sdk_version();
if (app_target_api_level < 23) {
const char* bname = basename(dt_needed);
if (bname != dt_needed) {
DL_WARN_documented_change(23,
"invalid-dt_needed-entries-enforced-for-api-level-23",
"library \"%s\" has invalid DT_NEEDED entry \"%s\"",
sopath, dt_needed, app_target_api_level);
add_dlwarning(sopath, "invalid DT_NEEDED entry", dt_needed);
}
return bname;
}
#endif
return dt_needed;
}
template<typename F>
static void for_each_dt_needed(const ElfReader& elf_reader, F action) {
for (const ElfW(Dyn)* d = elf_reader.dynamic(); d->d_tag != DT_NULL; ++d) {
if (d->d_tag == DT_NEEDED) {
action(fix_dt_needed(elf_reader.get_string(d->d_un.d_val), elf_reader.name()));
}
}
}
static bool find_loaded_library_by_inode(android_namespace_t* ns,
const struct stat& file_stat,
off64_t file_offset,
bool search_linked_namespaces,
soinfo** candidate) {
if (file_stat.st_dev == 0 || file_stat.st_ino == 0) {
*candidate = nullptr;
return false;
}
auto predicate = [&](soinfo* si) {
return si->get_st_ino() == file_stat.st_ino &&
si->get_st_dev() == file_stat.st_dev &&
si->get_file_offset() == file_offset;
};
*candidate = ns->soinfo_list().find_if(predicate);
if (*candidate == nullptr && search_linked_namespaces) {
for (auto& link : ns->linked_namespaces()) {
android_namespace_t* linked_ns = link.linked_namespace();
soinfo* si = linked_ns->soinfo_list().find_if(predicate);
if (si != nullptr && link.is_accessible(si->get_soname())) {
*candidate = si;
return true;
}
}
}
return *candidate != nullptr;
}
static bool find_loaded_library_by_realpath(android_namespace_t* ns, const char* realpath,
bool search_linked_namespaces, soinfo** candidate) {
auto predicate = [&](soinfo* si) { return strcmp(realpath, si->get_realpath()) == 0; };
*candidate = ns->soinfo_list().find_if(predicate);
if (*candidate == nullptr && search_linked_namespaces) {
for (auto& link : ns->linked_namespaces()) {
android_namespace_t* linked_ns = link.linked_namespace();
soinfo* si = linked_ns->soinfo_list().find_if(predicate);
if (si != nullptr && link.is_accessible(si->get_soname())) {
*candidate = si;
return true;
}
}
}
return *candidate != nullptr;
}
static bool load_library(android_namespace_t* ns,
LoadTask* task,
LoadTaskList* load_tasks,
int rtld_flags,
const std::string& realpath,
bool search_linked_namespaces) {
off64_t file_offset = task->get_file_offset();
const char* name = task->get_name();
const android_dlextinfo* extinfo = task->get_extinfo();
LD_LOG(kLogDlopen,
"load_library(ns=%s, task=%s, flags=0x%x, realpath=%s, search_linked_namespaces=%d)",
ns->get_name(), name, rtld_flags, realpath.c_str(), search_linked_namespaces);
if ((file_offset % page_size()) != 0) {
DL_OPEN_ERR("file offset for the library \"%s\" is not page-aligned: %" PRId64, name, file_offset);
return false;
}
if (file_offset < 0) {
DL_OPEN_ERR("file offset for the library \"%s\" is negative: %" PRId64, name, file_offset);
return false;
}
struct stat file_stat;
if (TEMP_FAILURE_RETRY(fstat(task->get_fd(), &file_stat)) != 0) {
DL_OPEN_ERR("unable to stat file for the library \"%s\": %m", name);
return false;
}
if (file_offset >= file_stat.st_size) {
DL_OPEN_ERR("file offset for the library \"%s\" >= file size: %" PRId64 " >= %" PRId64,
name, file_offset, file_stat.st_size);
return false;
}
// Check for symlink and other situations where
// file can have different names, unless ANDROID_DLEXT_FORCE_LOAD is set
if (extinfo == nullptr || (extinfo->flags & ANDROID_DLEXT_FORCE_LOAD) == 0) {
soinfo* si = nullptr;
if (find_loaded_library_by_inode(ns, file_stat, file_offset, search_linked_namespaces, &si)) {
LD_LOG(kLogDlopen,
"load_library(ns=%s, task=%s): Already loaded under different name/path \"%s\" - "
"will return existing soinfo",
ns->get_name(), name, si->get_realpath());
task->set_soinfo(si);
return true;
}
}
if ((rtld_flags & RTLD_NOLOAD) != 0) {
DL_OPEN_ERR("library \"%s\" wasn't loaded and RTLD_NOLOAD prevented it", name);
return false;
}
struct statfs fs_stat;
if (TEMP_FAILURE_RETRY(fstatfs(task->get_fd(), &fs_stat)) != 0) {
DL_OPEN_ERR("unable to fstatfs file for the library \"%s\": %m", name);
return false;
}
// do not check accessibility using realpath if fd is located on tmpfs
// this enables use of memfd_create() for apps
if ((fs_stat.f_type != TMPFS_MAGIC) && (!ns->is_accessible(realpath))) {
// TODO(dimitry): workaround for http://b/26394120 - the exempt-list
const soinfo* needed_by = task->is_dt_needed() ? task->get_needed_by() : nullptr;
if (is_exempt_lib(ns, name, needed_by)) {
// print warning only if needed by non-system library
if (needed_by == nullptr || !is_system_library(needed_by->get_realpath())) {
const soinfo* needed_or_dlopened_by = task->get_needed_by();
const char* sopath = needed_or_dlopened_by == nullptr ? "(unknown)" :
needed_or_dlopened_by->get_realpath();
DL_WARN_documented_change(24,
"private-api-enforced-for-api-level-24",
"library \"%s\" (\"%s\") needed or dlopened by \"%s\" "
"is not accessible by namespace \"%s\"",
name, realpath.c_str(), sopath, ns->get_name());
add_dlwarning(sopath, "unauthorized access to", name);
}
} else {
// do not load libraries if they are not accessible for the specified namespace.
const char* needed_or_dlopened_by = task->get_needed_by() == nullptr ?
"(unknown)" :
task->get_needed_by()->get_realpath();
DL_OPEN_ERR("library \"%s\" needed or dlopened by \"%s\" is not accessible for the namespace \"%s\"",
name, needed_or_dlopened_by, ns->get_name());
// do not print this if a library is in the list of shared libraries for linked namespaces
if (!maybe_accessible_via_namespace_links(ns, name)) {
DL_WARN("library \"%s\" (\"%s\") needed or dlopened by \"%s\" is not accessible for the"
" namespace: [name=\"%s\", ld_library_paths=\"%s\", default_library_paths=\"%s\","
" permitted_paths=\"%s\"]",
name, realpath.c_str(),
needed_or_dlopened_by,
ns->get_name(),
android::base::Join(ns->get_ld_library_paths(), ':').c_str(),
android::base::Join(ns->get_default_library_paths(), ':').c_str(),
android::base::Join(ns->get_permitted_paths(), ':').c_str());
}
return false;
}
}
soinfo* si = soinfo_alloc(ns, realpath.c_str(), &file_stat, file_offset, rtld_flags);
task->set_soinfo(si);
// Read the ELF header and some of the segments.
if (!task->read(realpath.c_str(), file_stat.st_size)) {
task->remove_cached_elf_reader();
task->set_soinfo(nullptr);
soinfo_free(si);
return false;
}
// Find and set DT_RUNPATH, DT_SONAME, and DT_FLAGS_1.
// Note that these field values are temporary and are
// going to be overwritten on soinfo::prelink_image
// with values from PT_LOAD segments.
const ElfReader& elf_reader = task->get_elf_reader();
for (const ElfW(Dyn)* d = elf_reader.dynamic(); d->d_tag != DT_NULL; ++d) {
if (d->d_tag == DT_RUNPATH) {
si->set_dt_runpath(elf_reader.get_string(d->d_un.d_val));
}
if (d->d_tag == DT_SONAME) {
si->set_soname(elf_reader.get_string(d->d_un.d_val));
}
// We need to identify a DF_1_GLOBAL library early so we can link it to namespaces.
if (d->d_tag == DT_FLAGS_1) {
si->set_dt_flags_1(d->d_un.d_val);
}
}
#if !defined(__ANDROID__)
// Bionic on the host currently uses some Android prebuilts, which don't set
// DT_RUNPATH with any relative paths, so they can't find their dependencies.
// b/118058804
if (si->get_dt_runpath().empty()) {
si->set_dt_runpath("$ORIGIN/../lib64:$ORIGIN/lib64");
}
#endif
for_each_dt_needed(task->get_elf_reader(), [&](const char* name) {
LD_LOG(kLogDlopen, "load_library(ns=%s, task=%s): Adding DT_NEEDED task: %s",
ns->get_name(), task->get_name(), name);
load_tasks->push_back(LoadTask::create(name, si, ns, task->get_readers_map()));
});
return true;
}
static bool load_library(android_namespace_t* ns,
LoadTask* task,
ZipArchiveCache* zip_archive_cache,
LoadTaskList* load_tasks,
int rtld_flags,
bool search_linked_namespaces) {
const char* name = task->get_name();
soinfo* needed_by = task->get_needed_by();
const android_dlextinfo* extinfo = task->get_extinfo();
if (extinfo != nullptr && (extinfo->flags & ANDROID_DLEXT_USE_LIBRARY_FD) != 0) {
off64_t file_offset = 0;
if ((extinfo->flags & ANDROID_DLEXT_USE_LIBRARY_FD_OFFSET) != 0) {
file_offset = extinfo->library_fd_offset;
}
std::string realpath;
if (!realpath_fd(extinfo->library_fd, &realpath)) {
if (!is_first_stage_init()) {
DL_WARN("unable to get realpath for the library \"%s\" by extinfo->library_fd. "
"Will use given name.",
name);
}
realpath = name;
}
task->set_fd(extinfo->library_fd, false);
task->set_file_offset(file_offset);
return load_library(ns, task, load_tasks, rtld_flags, realpath, search_linked_namespaces);
}
LD_LOG(kLogDlopen,
"load_library(ns=%s, task=%s, flags=0x%x, search_linked_namespaces=%d): calling "
"open_library",
ns->get_name(), name, rtld_flags, search_linked_namespaces);
// Open the file.
off64_t file_offset;
std::string realpath;
int fd = open_library(ns, zip_archive_cache, name, needed_by, &file_offset, &realpath);
if (fd == -1) {
if (task->is_dt_needed()) {
if (needed_by->is_main_executable()) {
DL_OPEN_ERR("library \"%s\" not found: needed by main executable", name);
} else {
DL_OPEN_ERR("library \"%s\" not found: needed by %s in namespace %s", name,
needed_by->get_realpath(), task->get_start_from()->get_name());
}
} else {
DL_OPEN_ERR("library \"%s\" not found", name);
}
return false;
}
task->set_fd(fd, true);
task->set_file_offset(file_offset);
return load_library(ns, task, load_tasks, rtld_flags, realpath, search_linked_namespaces);
}
static bool find_loaded_library_by_soname(android_namespace_t* ns,
const char* name,
soinfo** candidate) {
return !ns->soinfo_list().visit([&](soinfo* si) {
if (strcmp(name, si->get_soname()) == 0) {
*candidate = si;
return false;
}
return true;
});
}
// Returns true if library was found and false otherwise
static bool find_loaded_library_by_soname(android_namespace_t* ns,
const char* name,
bool search_linked_namespaces,
soinfo** candidate) {
*candidate = nullptr;
// Ignore filename with path.
if (strchr(name, '/') != nullptr) {
return false;
}
bool found = find_loaded_library_by_soname(ns, name, candidate);
if (!found && search_linked_namespaces) {
// if a library was not found - look into linked namespaces
for (auto& link : ns->linked_namespaces()) {
if (!link.is_accessible(name)) {
continue;
}
android_namespace_t* linked_ns = link.linked_namespace();
if (find_loaded_library_by_soname(linked_ns, name, candidate)) {
return true;
}
}
}
return found;
}
static bool find_library_in_linked_namespace(const android_namespace_link_t& namespace_link,
LoadTask* task) {
android_namespace_t* ns = namespace_link.linked_namespace();
soinfo* candidate;
bool loaded = false;
std::string soname;
if (find_loaded_library_by_soname(ns, task->get_name(), false, &candidate)) {
loaded = true;
soname = candidate->get_soname();
} else {
soname = resolve_soname(task->get_name());
}
if (!namespace_link.is_accessible(soname.c_str())) {
// the library is not accessible via namespace_link
LD_LOG(kLogDlopen,
"find_library_in_linked_namespace(ns=%s, task=%s): Not accessible (soname=%s)",
ns->get_name(), task->get_name(), soname.c_str());
return false;
}
// if library is already loaded - return it
if (loaded) {
LD_LOG(kLogDlopen, "find_library_in_linked_namespace(ns=%s, task=%s): Already loaded",
ns->get_name(), task->get_name());
task->set_soinfo(candidate);
return true;
}
// returning true with empty soinfo means that the library is okay to be
// loaded in the namespace but has not yet been loaded there before.
LD_LOG(kLogDlopen, "find_library_in_linked_namespace(ns=%s, task=%s): Ok to load", ns->get_name(),
task->get_name());
task->set_soinfo(nullptr);
return true;
}
static bool find_library_internal(android_namespace_t* ns,
LoadTask* task,
ZipArchiveCache* zip_archive_cache,
LoadTaskList* load_tasks,
int rtld_flags) {
soinfo* candidate;
if (find_loaded_library_by_soname(ns, task->get_name(), true /* search_linked_namespaces */,
&candidate)) {
LD_LOG(kLogDlopen,
"find_library_internal(ns=%s, task=%s): Already loaded (by soname): %s",
ns->get_name(), task->get_name(), candidate->get_realpath());
task->set_soinfo(candidate);
return true;
}
// Library might still be loaded, the accurate detection
// of this fact is done by load_library.
LD_DEBUG(any, "[ \"%s\" find_loaded_library_by_soname failed (*candidate=%s@%p). Trying harder... ]",
task->get_name(), candidate == nullptr ? "n/a" : candidate->get_realpath(), candidate);
if (load_library(ns, task, zip_archive_cache, load_tasks, rtld_flags,
true /* search_linked_namespaces */)) {
return true;
}
// TODO(dimitry): workaround for http://b/26394120 (the exempt-list)
if (ns->is_exempt_list_enabled() && is_exempt_lib(ns, task->get_name(), task->get_needed_by())) {
// For the libs in the exempt-list, switch to the default namespace and then
// try the load again from there. The library could be loaded from the
// default namespace or from another namespace (e.g. runtime) that is linked
// from the default namespace.
LD_LOG(kLogDlopen,
"find_library_internal(ns=%s, task=%s): Exempt system library - trying namespace %s",
ns->get_name(), task->get_name(), g_default_namespace.get_name());
ns = &g_default_namespace;
if (load_library(ns, task, zip_archive_cache, load_tasks, rtld_flags,
true /* search_linked_namespaces */)) {
return true;
}
}
// END OF WORKAROUND
// if a library was not found - look into linked namespaces
// preserve current dlerror in the case it fails.
DlErrorRestorer dlerror_restorer;
LD_LOG(kLogDlopen, "find_library_internal(ns=%s, task=%s): Trying %zu linked namespaces",
ns->get_name(), task->get_name(), ns->linked_namespaces().size());
for (auto& linked_namespace : ns->linked_namespaces()) {
if (find_library_in_linked_namespace(linked_namespace, task)) {
// Library is already loaded.
if (task->get_soinfo() != nullptr) {
// n.b. This code path runs when find_library_in_linked_namespace found an already-loaded
// library by soname. That should only be possible with a exempt-list lookup, where we
// switch the namespace, because otherwise, find_library_in_linked_namespace is duplicating
// the soname scan done in this function's first call to find_loaded_library_by_soname.
return true;
}
if (load_library(linked_namespace.linked_namespace(), task, zip_archive_cache, load_tasks,
rtld_flags, false /* search_linked_namespaces */)) {
LD_LOG(kLogDlopen, "find_library_internal(ns=%s, task=%s): Found in linked namespace %s",
ns->get_name(), task->get_name(), linked_namespace.linked_namespace()->get_name());
return true;
}
}
}
return false;
}
static void soinfo_unload(soinfo* si);
static void shuffle(std::vector<LoadTask*>* v) {
if (is_first_stage_init()) {
// arc4random* is not available in first stage init because /dev/random
// hasn't yet been created.
return;
}
for (size_t i = 0, size = v->size(); i < size; ++i) {
size_t n = size - i;
size_t r = arc4random_uniform(n);
std::swap((*v)[n-1], (*v)[r]);
}
}
// add_as_children - add first-level loaded libraries (i.e. library_names[], but
// not their transitive dependencies) as children of the start_with library.
// This is false when find_libraries is called for dlopen(), when newly loaded
// libraries must form a disjoint tree.
bool find_libraries(android_namespace_t* ns,
soinfo* start_with,
const char* const library_names[],
size_t library_names_count,
soinfo* soinfos[],
std::vector<soinfo*>* ld_preloads,
size_t ld_preloads_count,
int rtld_flags,
const android_dlextinfo* extinfo,
bool add_as_children,
std::vector<android_namespace_t*>* namespaces) {
// Step 0: prepare.
std::unordered_map<const soinfo*, ElfReader> readers_map;
LoadTaskList load_tasks;
for (size_t i = 0; i < library_names_count; ++i) {
const char* name = library_names[i];
load_tasks.push_back(LoadTask::create(name, start_with, ns, &readers_map));
}
// If soinfos array is null allocate one on stack.
// The array is needed in case of failure; for example
// when library_names[] = {libone.so, libtwo.so} and libone.so
// is loaded correctly but libtwo.so failed for some reason.
// In this case libone.so should be unloaded on return.
// See also implementation of failure_guard below.
if (soinfos == nullptr) {
size_t soinfos_size = sizeof(soinfo*)*library_names_count;
soinfos = reinterpret_cast<soinfo**>(alloca(soinfos_size));
memset(soinfos, 0, soinfos_size);
}
// list of libraries to link - see step 2.
size_t soinfos_count = 0;
auto scope_guard = android::base::make_scope_guard([&]() {
for (LoadTask* t : load_tasks) {
LoadTask::deleter(t);
}
});
ZipArchiveCache zip_archive_cache;
soinfo_list_t new_global_group_members;
// Step 1: expand the list of load_tasks to include
// all DT_NEEDED libraries (do not load them just yet)
for (size_t i = 0; i<load_tasks.size(); ++i) {
LoadTask* task = load_tasks[i];
soinfo* needed_by = task->get_needed_by();
bool is_dt_needed = needed_by != nullptr && (needed_by != start_with || add_as_children);
task->set_extinfo(is_dt_needed ? nullptr : extinfo);
task->set_dt_needed(is_dt_needed);
// Note: start from the namespace that is stored in the LoadTask. This namespace
// is different from the current namespace when the LoadTask is for a transitive
// dependency and the lib that created the LoadTask is not found in the
// current namespace but in one of the linked namespaces.
android_namespace_t* start_ns = const_cast<android_namespace_t*>(task->get_start_from());
LD_LOG(kLogDlopen, "find_library_internal(ns=%s@%p): task=%s, is_dt_needed=%d",
start_ns->get_name(), start_ns, task->get_name(), is_dt_needed);
if (!find_library_internal(start_ns, task, &zip_archive_cache, &load_tasks, rtld_flags)) {
return false;
}
soinfo* si = task->get_soinfo();
if (is_dt_needed) {
needed_by->add_child(si);
}
// When ld_preloads is not null, the first
// ld_preloads_count libs are in fact ld_preloads.
bool is_ld_preload = false;
if (ld_preloads != nullptr && soinfos_count < ld_preloads_count) {
ld_preloads->push_back(si);
is_ld_preload = true;
}
if (soinfos_count < library_names_count) {
soinfos[soinfos_count++] = si;
}
// Add the new global group members to all initial namespaces. Do this secondary namespace setup
// at the same time that libraries are added to their primary namespace so that the order of
// global group members is the same in the every namespace. Only add a library to a namespace
// once, even if it appears multiple times in the dependency graph.
if (is_ld_preload || (si->get_dt_flags_1() & DF_1_GLOBAL) != 0) {
if (!si->is_linked() && namespaces != nullptr && !new_global_group_members.contains(si)) {
new_global_group_members.push_back(si);
for (auto linked_ns : *namespaces) {
if (si->get_primary_namespace() != linked_ns) {
linked_ns->add_soinfo(si);
si->add_secondary_namespace(linked_ns);
}
}
}
}
}
// Step 2: Load libraries in random order (see b/24047022)
LoadTaskList load_list;
for (auto&& task : load_tasks) {
soinfo* si = task->get_soinfo();
auto pred = [&](const LoadTask* t) {
return t->get_soinfo() == si;
};
if (!si->is_linked() &&
std::find_if(load_list.begin(), load_list.end(), pred) == load_list.end() ) {
load_list.push_back(task);
}
}
bool reserved_address_recursive = false;
if (extinfo) {
reserved_address_recursive = extinfo->flags & ANDROID_DLEXT_RESERVED_ADDRESS_RECURSIVE;
}
if (!reserved_address_recursive) {
// Shuffle the load order in the normal case, but not if we are loading all
// the libraries to a reserved address range.
shuffle(&load_list);
}
// Set up address space parameters.
address_space_params extinfo_params, default_params;
size_t relro_fd_offset = 0;
if (extinfo) {
if (extinfo->flags & ANDROID_DLEXT_RESERVED_ADDRESS) {
extinfo_params.start_addr = extinfo->reserved_addr;
extinfo_params.reserved_size = extinfo->reserved_size;
extinfo_params.must_use_address = true;
} else if (extinfo->flags & ANDROID_DLEXT_RESERVED_ADDRESS_HINT) {
extinfo_params.start_addr = extinfo->reserved_addr;
extinfo_params.reserved_size = extinfo->reserved_size;
}
}
for (auto&& task : load_list) {
address_space_params* address_space =
(reserved_address_recursive || !task->is_dt_needed()) ? &extinfo_params : &default_params;
if (!task->load(address_space)) {
return false;
}
}
// Step 3: pre-link all DT_NEEDED libraries in breadth first order.
bool any_memtag_stack = false;
for (auto&& task : load_tasks) {
soinfo* si = task->get_soinfo();
if (!si->is_linked() && !si->prelink_image()) {
return false;
}
// si->memtag_stack() needs to be called after si->prelink_image() which populates
// the dynamic section.
if (si->has_min_version(7) && si->memtag_stack()) {
any_memtag_stack = true;
LD_LOG(kLogDlopen,
"... load_library requesting stack MTE for: realpath=\"%s\", soname=\"%s\"",
si->get_realpath(), si->get_soname());
}
register_soinfo_tls(si);
}
if (any_memtag_stack) {
if (auto* cb = __libc_shared_globals()->memtag_stack_dlopen_callback) {
cb();
} else {
// find_library is used by the initial linking step, so we communicate that we
// want memtag_stack enabled to __libc_init_mte.
__libc_shared_globals()->initial_memtag_stack = true;
}
}
// Step 4: Construct the global group. DF_1_GLOBAL bit is force set for LD_PRELOADed libs because
// they must be added to the global group. Note: The DF_1_GLOBAL bit for a library is normally set
// in step 3.
if (ld_preloads != nullptr) {
for (auto&& si : *ld_preloads) {
si->set_dt_flags_1(si->get_dt_flags_1() | DF_1_GLOBAL);
}
}
// Step 5: Collect roots of local_groups.
// Whenever needed_by->si link crosses a namespace boundary it forms its own local_group.
// Here we collect new roots to link them separately later on. Note that we need to avoid
// collecting duplicates. Also the order is important. They need to be linked in the same
// BFS order we link individual libraries.
std::vector<soinfo*> local_group_roots;
if (start_with != nullptr && add_as_children) {
local_group_roots.push_back(start_with);
} else {
CHECK(soinfos_count == 1);
local_group_roots.push_back(soinfos[0]);
}
for (auto&& task : load_tasks) {
soinfo* si = task->get_soinfo();
soinfo* needed_by = task->get_needed_by();
bool is_dt_needed = needed_by != nullptr && (needed_by != start_with || add_as_children);
android_namespace_t* needed_by_ns =
is_dt_needed ? needed_by->get_primary_namespace() : ns;
if (!si->is_linked() && si->get_primary_namespace() != needed_by_ns) {
auto it = std::find(local_group_roots.begin(), local_group_roots.end(), si);
LD_LOG(kLogDlopen,
"Crossing namespace boundary (si=%s@%p, si_ns=%s@%p, needed_by=%s@%p, ns=%s@%p, needed_by_ns=%s@%p) adding to local_group_roots: %s",
si->get_realpath(),
si,
si->get_primary_namespace()->get_name(),
si->get_primary_namespace(),
needed_by == nullptr ? "(nullptr)" : needed_by->get_realpath(),
needed_by,
ns->get_name(),
ns,
needed_by_ns->get_name(),
needed_by_ns,
it == local_group_roots.end() ? "yes" : "no");
if (it == local_group_roots.end()) {
local_group_roots.push_back(si);
}
}
}
// Step 6: Link all local groups
for (auto root : local_group_roots) {
soinfo_list_t local_group;
android_namespace_t* local_group_ns = root->get_primary_namespace();
walk_dependencies_tree(root,
[&] (soinfo* si) {
if (local_group_ns->is_accessible(si)) {
local_group.push_back(si);
return kWalkContinue;
} else {
return kWalkSkip;
}
});
soinfo_list_t global_group = local_group_ns->get_global_group();
SymbolLookupList lookup_list(global_group, local_group);
soinfo* local_group_root = local_group.front();
bool linked = local_group.visit([&](soinfo* si) {
// Even though local group may contain accessible soinfos from other namespaces
// we should avoid linking them (because if they are not linked -> they
// are in the local_group_roots and will be linked later).
if (!si->is_linked() && si->get_primary_namespace() == local_group_ns) {
const android_dlextinfo* link_extinfo = nullptr;
if (si == soinfos[0] || reserved_address_recursive) {
// Only forward extinfo for the first library unless the recursive
// flag is set.
link_extinfo = extinfo;
}
if (__libc_shared_globals()->load_hook) {
__libc_shared_globals()->load_hook(si->load_bias, si->phdr, si->phnum);
}
lookup_list.set_dt_symbolic_lib(si->has_DT_SYMBOLIC ? si : nullptr);
if (!si->link_image(lookup_list, local_group_root, link_extinfo, &relro_fd_offset) ||
!get_cfi_shadow()->AfterLoad(si, solist_get_head())) {
return false;
}
}
return true;
});
if (!linked) {
return false;
}
}
// Step 7: Mark all load_tasks as linked and increment refcounts
// for references between load_groups (at this point it does not matter if
// referenced load_groups were loaded by previous dlopen or as part of this
// one on step 6)
if (start_with != nullptr && add_as_children) {
start_with->set_linked();
}
for (auto&& task : load_tasks) {
soinfo* si = task->get_soinfo();
si->set_linked();
}
for (auto&& task : load_tasks) {
soinfo* si = task->get_soinfo();
soinfo* needed_by = task->get_needed_by();
if (needed_by != nullptr &&
needed_by != start_with &&
needed_by->get_local_group_root() != si->get_local_group_root()) {
si->increment_ref_count();
}
}
return true;
}
static soinfo* find_library(android_namespace_t* ns,
const char* name, int rtld_flags,
const android_dlextinfo* extinfo,
soinfo* needed_by) {
soinfo* si = nullptr;
if (name == nullptr) {
si = solist_get_somain();
} else if (!find_libraries(ns,
needed_by,
&name,
1,
&si,
nullptr,
0,
rtld_flags,
extinfo,
false /* add_as_children */)) {
if (si != nullptr) {
soinfo_unload(si);
}
return nullptr;
}
si->increment_ref_count();
return si;
}
static void soinfo_unload_impl(soinfo* root) {
ScopedTrace trace((std::string("unload ") + root->get_realpath()).c_str());
bool is_linked = root->is_linked();
if (!root->can_unload()) {
LD_LOG(kLogDlopen,
"... dlclose(root=\"%s\"@%p) ... not unloading - the load group is flagged with NODELETE",
root->get_realpath(),
root);
return;
}
soinfo_list_t unload_list;
unload_list.push_back(root);
soinfo_list_t local_unload_list;
soinfo_list_t external_unload_list;
soinfo* si = nullptr;
while ((si = unload_list.pop_front()) != nullptr) {
if (local_unload_list.contains(si)) {
continue;
}
local_unload_list.push_back(si);
if (si->has_min_version(0)) {
soinfo* child = nullptr;
while ((child = si->get_children().pop_front()) != nullptr) {
LD_DEBUG(any, "%s@%p needs to unload %s@%p", si->get_realpath(), si,
child->get_realpath(), child);
child->get_parents().remove(si);
if (local_unload_list.contains(child)) {
continue;
} else if (child->is_linked() && child->get_local_group_root() != root) {
external_unload_list.push_back(child);
} else if (child->get_parents().empty()) {
unload_list.push_back(child);
}
}
} else {
async_safe_fatal("soinfo for \"%s\"@%p has no version", si->get_realpath(), si);
}
}
local_unload_list.for_each([](soinfo* si) {
LD_LOG(kLogDlopen,
"... dlclose: calling destructors for \"%s\"@%p ... ",
si->get_realpath(),
si);
si->call_destructors();
LD_LOG(kLogDlopen,
"... dlclose: calling destructors for \"%s\"@%p ... done",
si->get_realpath(),
si);
});
while ((si = local_unload_list.pop_front()) != nullptr) {
LD_LOG(kLogDlopen,
"... dlclose: unloading \"%s\"@%p ...",
si->get_realpath(),
si);
++g_module_unload_counter;
notify_gdb_of_unload(si);
unregister_soinfo_tls(si);
if (__libc_shared_globals()->unload_hook) {
__libc_shared_globals()->unload_hook(si->load_bias, si->phdr, si->phnum);
}
get_cfi_shadow()->BeforeUnload(si);
soinfo_free(si);
}
if (is_linked) {
while ((si = external_unload_list.pop_front()) != nullptr) {
LD_LOG(kLogDlopen,
"... dlclose: unloading external reference \"%s\"@%p ...",
si->get_realpath(),
si);
soinfo_unload(si);
}
} else {
LD_LOG(kLogDlopen,
"... dlclose: unload_si was not linked - not unloading external references ...");
}
}
static void soinfo_unload(soinfo* unload_si) {
// Note that the library can be loaded but not linked;
// in which case there is no root but we still need
// to walk the tree and unload soinfos involved.
//
// This happens on unsuccessful dlopen, when one of
// the DT_NEEDED libraries could not be linked/found.
bool is_linked = unload_si->is_linked();
soinfo* root = is_linked ? unload_si->get_local_group_root() : unload_si;
LD_LOG(kLogDlopen,
"... dlclose(realpath=\"%s\"@%p) ... load group root is \"%s\"@%p",
unload_si->get_realpath(),
unload_si,
root->get_realpath(),
root);
size_t ref_count = is_linked ? root->decrement_ref_count() : 0;
if (ref_count > 0) {
LD_LOG(kLogDlopen,
"... dlclose(root=\"%s\"@%p) ... not unloading - decrementing ref_count to %zd",
root->get_realpath(),
root,
ref_count);
return;
}
soinfo_unload_impl(root);
}
void increment_dso_handle_reference_counter(void* dso_handle) {
if (dso_handle == nullptr) {
return;
}
auto it = g_dso_handle_counters.find(dso_handle);
if (it != g_dso_handle_counters.end()) {
CHECK(++it->second != 0);
} else {
soinfo* si = find_containing_library(dso_handle);
if (si != nullptr) {
ProtectedDataGuard guard;
si->increment_ref_count();
} else {
async_safe_fatal(
"increment_dso_handle_reference_counter: Couldn't find soinfo by dso_handle=%p",
dso_handle);
}
g_dso_handle_counters[dso_handle] = 1U;
}
}
void decrement_dso_handle_reference_counter(void* dso_handle) {
if (dso_handle == nullptr) {
return;
}
auto it = g_dso_handle_counters.find(dso_handle);
CHECK(it != g_dso_handle_counters.end());
CHECK(it->second != 0);
if (--it->second == 0) {
soinfo* si = find_containing_library(dso_handle);
if (si != nullptr) {
ProtectedDataGuard guard;
soinfo_unload(si);
} else {
async_safe_fatal(
"decrement_dso_handle_reference_counter: Couldn't find soinfo by dso_handle=%p",
dso_handle);
}
g_dso_handle_counters.erase(it);
}
}
static std::string symbol_display_name(const char* sym_name, const char* sym_ver) {
if (sym_ver == nullptr) {
return sym_name;
}
return std::string(sym_name) + ", version " + sym_ver;
}
static android_namespace_t* get_caller_namespace(soinfo* caller) {
return caller != nullptr ? caller->get_primary_namespace() : g_anonymous_namespace;
}
void do_android_get_LD_LIBRARY_PATH(char* buffer, size_t buffer_size) {
// Use basic string manipulation calls to avoid snprintf.
// snprintf indirectly calls pthread_getspecific to get the size of a buffer.
// When debug malloc is enabled, this call returns 0. This in turn causes
// snprintf to do nothing, which causes libraries to fail to load.
// See b/17302493 for further details.
// Once the above bug is fixed, this code can be modified to use
// snprintf again.
const auto& default_ld_paths = g_default_namespace.get_default_library_paths();
size_t required_size = 0;
for (const auto& path : default_ld_paths) {
required_size += path.size() + 1;
}
if (buffer_size < required_size) {
async_safe_fatal("android_get_LD_LIBRARY_PATH failed, buffer too small: "
"buffer len %zu, required len %zu", buffer_size, required_size);
}
char* end = buffer;
for (size_t i = 0; i < default_ld_paths.size(); ++i) {
if (i > 0) *end++ = ':';
end = stpcpy(end, default_ld_paths[i].c_str());
}
}
void do_android_update_LD_LIBRARY_PATH(const char* ld_library_path) {
parse_LD_LIBRARY_PATH(ld_library_path);
}
static std::string android_dlextinfo_to_string(const android_dlextinfo* info) {
if (info == nullptr) {
return "(null)";
}
return android::base::StringPrintf("[flags=0x%" PRIx64 ","
" reserved_addr=%p,"
" reserved_size=0x%zx,"
" relro_fd=%d,"
" library_fd=%d,"
" library_fd_offset=0x%" PRIx64 ","
" library_namespace=%s@%p]",
info->flags,
info->reserved_addr,
info->reserved_size,
info->relro_fd,
info->library_fd,
info->library_fd_offset,
(info->flags & ANDROID_DLEXT_USE_NAMESPACE) != 0 ?
(info->library_namespace != nullptr ?
info->library_namespace->get_name() : "(null)") : "(n/a)",
(info->flags & ANDROID_DLEXT_USE_NAMESPACE) != 0 ?
info->library_namespace : nullptr);
}
void* do_dlopen(const char* name, int flags,
const android_dlextinfo* extinfo,
const void* caller_addr) {
std::string trace_prefix = std::string("dlopen: ") + (name == nullptr ? "(nullptr)" : name);
ScopedTrace trace(trace_prefix.c_str());
ScopedTrace loading_trace((trace_prefix + " - loading and linking").c_str());
soinfo* const caller = find_containing_library(caller_addr);
android_namespace_t* ns = get_caller_namespace(caller);
LD_LOG(kLogDlopen,
"dlopen(name=\"%s\", flags=0x%x, extinfo=%s, caller=\"%s\", caller_ns=%s@%p, targetSdkVersion=%i) ...",
name,
flags,
android_dlextinfo_to_string(extinfo).c_str(),
caller == nullptr ? "(null)" : caller->get_realpath(),
ns == nullptr ? "(null)" : ns->get_name(),
ns,
get_application_target_sdk_version());
auto purge_guard = android::base::make_scope_guard([&]() { purge_unused_memory(); });
auto failure_guard = android::base::make_scope_guard(
[&]() { LD_LOG(kLogDlopen, "... dlopen failed: %s", linker_get_error_buffer()); });
if ((flags & ~(RTLD_NOW|RTLD_LAZY|RTLD_LOCAL|RTLD_GLOBAL|RTLD_NODELETE|RTLD_NOLOAD)) != 0) {
DL_OPEN_ERR("invalid flags to dlopen: %x", flags);
return nullptr;
}
if (extinfo != nullptr) {
if ((extinfo->flags & ~(ANDROID_DLEXT_VALID_FLAG_BITS)) != 0) {
DL_OPEN_ERR("invalid extended flags to android_dlopen_ext: 0x%" PRIx64, extinfo->flags);
return nullptr;
}
if ((extinfo->flags & ANDROID_DLEXT_USE_LIBRARY_FD) == 0 &&
(extinfo->flags & ANDROID_DLEXT_USE_LIBRARY_FD_OFFSET) != 0) {
DL_OPEN_ERR("invalid extended flag combination (ANDROID_DLEXT_USE_LIBRARY_FD_OFFSET without "
"ANDROID_DLEXT_USE_LIBRARY_FD): 0x%" PRIx64, extinfo->flags);
return nullptr;
}
if ((extinfo->flags & ANDROID_DLEXT_USE_NAMESPACE) != 0) {
if (extinfo->library_namespace == nullptr) {
DL_OPEN_ERR("ANDROID_DLEXT_USE_NAMESPACE is set but extinfo->library_namespace is null");
return nullptr;
}
ns = extinfo->library_namespace;
}
}
// Workaround for dlopen(/system/lib/<soname>) when .so is in /apex. http://b/121248172
// The workaround works only when targetSdkVersion < Q.
std::string name_to_apex;
if (translateSystemPathToApexPath(name, &name_to_apex)) {
const char* new_name = name_to_apex.c_str();
LD_LOG(kLogDlopen, "dlopen considering translation from %s to APEX path %s",
name,
new_name);
// Some APEXs could be optionally disabled. Only translate the path
// when the old file is absent and the new file exists.
// TODO(b/124218500): Re-enable it once app compat issue is resolved
/*
if (file_exists(name)) {
LD_LOG(kLogDlopen, "dlopen %s exists, not translating", name);
} else
*/
if (!file_exists(new_name)) {
LD_LOG(kLogDlopen, "dlopen %s does not exist, not translating",
new_name);
} else {
LD_LOG(kLogDlopen, "dlopen translation accepted: using %s", new_name);
name = new_name;
}
}
// End Workaround for dlopen(/system/lib/<soname>) when .so is in /apex.
std::string translated_name_holder;
assert(!g_is_hwasan || !g_is_asan);
const char* translated_name = name;
if (g_is_asan && translated_name != nullptr && translated_name[0] == '/') {
char original_path[PATH_MAX];
if (realpath(name, original_path) != nullptr) {
translated_name_holder = std::string(kAsanLibDirPrefix) + original_path;
if (file_exists(translated_name_holder.c_str())) {
soinfo* si = nullptr;
if (find_loaded_library_by_realpath(ns, original_path, true, &si)) {
DL_WARN("linker_asan dlopen NOT translating \"%s\" -> \"%s\": library already loaded", name,
translated_name_holder.c_str());
} else {
DL_WARN("linker_asan dlopen translating \"%s\" -> \"%s\"", name, translated_name);
translated_name = translated_name_holder.c_str();
}
}
}
} else if (g_is_hwasan && translated_name != nullptr && translated_name[0] == '/') {
char original_path[PATH_MAX];
if (realpath(name, original_path) != nullptr) {
// Keep this the same as CreateHwasanPath in system/linkerconfig/modules/namespace.cc.
std::string path(original_path);
auto slash = path.rfind('/');
if (slash != std::string::npos || slash != path.size() - 1) {
translated_name_holder = path.substr(0, slash) + "/hwasan" + path.substr(slash);
}
if (!translated_name_holder.empty() && file_exists(translated_name_holder.c_str())) {
soinfo* si = nullptr;
if (find_loaded_library_by_realpath(ns, original_path, true, &si)) {
DL_WARN("linker_hwasan dlopen NOT translating \"%s\" -> \"%s\": library already loaded",
name, translated_name_holder.c_str());
} else {
DL_WARN("linker_hwasan dlopen translating \"%s\" -> \"%s\"", name, translated_name);
translated_name = translated_name_holder.c_str();
}
}
}
}
ProtectedDataGuard guard;
soinfo* si = find_library(ns, translated_name, flags, extinfo, caller);
loading_trace.End();
if (si != nullptr) {
void* handle = si->to_handle();
LD_LOG(kLogDlopen,
"... dlopen calling constructors: realpath=\"%s\", soname=\"%s\", handle=%p",
si->get_realpath(), si->get_soname(), handle);
si->call_constructors();
failure_guard.Disable();
LD_LOG(kLogDlopen,
"... dlopen successful: realpath=\"%s\", soname=\"%s\", handle=%p",
si->get_realpath(), si->get_soname(), handle);
return handle;
}
return nullptr;
}
int do_dladdr(const void* addr, Dl_info* info) {
// Determine if this address can be found in any library currently mapped.
soinfo* si = find_containing_library(addr);
if (si == nullptr) {
return 0;
}
memset(info, 0, sizeof(Dl_info));
info->dli_fname = si->get_realpath();
// Address at which the shared object is loaded.
info->dli_fbase = reinterpret_cast<void*>(si->base);
// Determine if any symbol in the library contains the specified address.
ElfW(Sym)* sym = si->find_symbol_by_address(addr);
if (sym != nullptr) {
info->dli_sname = si->get_string(sym->st_name);
info->dli_saddr = reinterpret_cast<void*>(si->resolve_symbol_address(sym));
}
return 1;
}
static soinfo* soinfo_from_handle(void* handle) {
if ((reinterpret_cast<uintptr_t>(handle) & 1) != 0) {
auto it = g_soinfo_handles_map.find(reinterpret_cast<uintptr_t>(handle));
if (it == g_soinfo_handles_map.end()) {
return nullptr;
} else {
return it->second;
}
}
return static_cast<soinfo*>(handle);
}
bool do_dlsym(void* handle,
const char* sym_name,
const char* sym_ver,
const void* caller_addr,
void** symbol) {
ScopedTrace trace("dlsym");
#if !defined(__LP64__)
if (handle == nullptr) {
DL_SYM_ERR("dlsym failed: library handle is null");
return false;
}
#endif
soinfo* found = nullptr;
const ElfW(Sym)* sym = nullptr;
soinfo* caller = find_containing_library(caller_addr);
android_namespace_t* ns = get_caller_namespace(caller);
soinfo* si = nullptr;
if (handle != RTLD_DEFAULT && handle != RTLD_NEXT) {
si = soinfo_from_handle(handle);
}
LD_LOG(kLogDlsym,
"dlsym(handle=%p(\"%s\"), sym_name=\"%s\", sym_ver=\"%s\", caller=\"%s\", caller_ns=%s@%p) ...",
handle,
si != nullptr ? si->get_realpath() : "n/a",
sym_name,
sym_ver,
caller == nullptr ? "(null)" : caller->get_realpath(),
ns == nullptr ? "(null)" : ns->get_name(),
ns);
auto failure_guard = android::base::make_scope_guard(
[&]() { LD_LOG(kLogDlsym, "... dlsym failed: %s", linker_get_error_buffer()); });
if (sym_name == nullptr) {
DL_SYM_ERR("dlsym failed: symbol name is null");
return false;
}
version_info vi_instance;
version_info* vi = nullptr;
if (sym_ver != nullptr) {
vi_instance.name = sym_ver;
vi_instance.elf_hash = calculate_elf_hash(sym_ver);
vi = &vi_instance;
}
if (handle == RTLD_DEFAULT || handle == RTLD_NEXT) {
sym = dlsym_linear_lookup(ns, sym_name, vi, &found, caller, handle);
} else {
if (si == nullptr) {
DL_SYM_ERR("dlsym failed: invalid handle: %p", handle);
return false;
}
sym = dlsym_handle_lookup(si, &found, sym_name, vi);
}
if (sym != nullptr) {
uint32_t bind = ELF_ST_BIND(sym->st_info);
uint32_t type = ELF_ST_TYPE(sym->st_info);
if ((bind == STB_GLOBAL || bind == STB_WEAK) && sym->st_shndx != 0) {
if (type == STT_TLS) {
// For a TLS symbol, dlsym returns the address of the current thread's
// copy of the symbol.
const soinfo_tls* tls_module = found->get_tls();
if (tls_module == nullptr) {
DL_SYM_ERR("TLS symbol \"%s\" in solib \"%s\" with no TLS segment",
sym_name, found->get_realpath());
return false;
}
void* tls_block = get_tls_block_for_this_thread(tls_module, /*should_alloc=*/true);
*symbol = static_cast<char*>(tls_block) + sym->st_value;
} else {
*symbol = reinterpret_cast<void*>(found->resolve_symbol_address(sym));
}
failure_guard.Disable();
LD_LOG(kLogDlsym,
"... dlsym successful: sym_name=\"%s\", sym_ver=\"%s\", found in=\"%s\", address=%p",
sym_name, sym_ver, found->get_soname(), *symbol);
return true;
}
DL_SYM_ERR("symbol \"%s\" found but not global", symbol_display_name(sym_name, sym_ver).c_str());
return false;
}
DL_SYM_ERR("undefined symbol: %s", symbol_display_name(sym_name, sym_ver).c_str());
return false;
}
int do_dlclose(void* handle) {
ScopedTrace trace("dlclose");
ProtectedDataGuard guard;
soinfo* si = soinfo_from_handle(handle);
if (si == nullptr) {
DL_OPEN_ERR("invalid handle: %p", handle);
return -1;
}
LD_LOG(kLogDlopen,
"dlclose(handle=%p, realpath=\"%s\"@%p) ...",
handle,
si->get_realpath(),
si);
soinfo_unload(si);
LD_LOG(kLogDlopen,
"dlclose(handle=%p) ... done",
handle);
return 0;
}
// Make ns as the anonymous namespace that is a namespace used when
// we fail to determine the caller address (e.g., call from mono-jited code)
// Since there can be multiple anonymous namespace in a process, subsequent
// call to this function causes an error.
static bool set_anonymous_namespace(android_namespace_t* ns) {
if (!g_anonymous_namespace_set && ns != nullptr) {
CHECK(ns->is_also_used_as_anonymous());
g_anonymous_namespace = ns;
g_anonymous_namespace_set = true;
return true;
}
return false;
}
// TODO(b/130388701) remove this. Currently, this is used only for testing
// where we don't have classloader namespace.
bool init_anonymous_namespace(const char* shared_lib_sonames, const char* library_search_path) {
ProtectedDataGuard guard;
// Test-only feature: we need to change the anonymous namespace multiple times
// while the test is running.
g_anonymous_namespace_set = false;
// create anonymous namespace
// When the caller is nullptr - create_namespace will take global group
// from the anonymous namespace, which is fine because anonymous namespace
// is still pointing to the default one.
android_namespace_t* anon_ns =
create_namespace(nullptr,
"(anonymous)",
nullptr,
library_search_path,
ANDROID_NAMESPACE_TYPE_ISOLATED |
ANDROID_NAMESPACE_TYPE_ALSO_USED_AS_ANONYMOUS,
nullptr,
&g_default_namespace);
CHECK(anon_ns != nullptr);
if (!link_namespaces(anon_ns, &g_default_namespace, shared_lib_sonames)) {
// TODO: delete anon_ns
return false;
}
return true;
}
static void add_soinfos_to_namespace(const soinfo_list_t& soinfos, android_namespace_t* ns) {
ns->add_soinfos(soinfos);
for (auto si : soinfos) {
si->add_secondary_namespace(ns);
}
}
std::vector<std::string> fix_lib_paths(std::vector<std::string> paths) {
// For the bootstrap linker, insert /system/${LIB}/bootstrap in front of /system/${LIB} in any
// namespace search path. The bootstrap linker should prefer to use the bootstrap bionic libraries
// (e.g. libc.so).
#if !defined(__ANDROID_APEX__)
for (size_t i = 0; i < paths.size(); ++i) {
if (paths[i] == kSystemLibDir) {
paths.insert(paths.begin() + i, std::string(kSystemLibDir) + "/bootstrap");
++i;
}
}
#endif
return paths;
}
android_namespace_t* create_namespace(const void* caller_addr,
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) {
if (parent_namespace == nullptr) {
// if parent_namespace is nullptr -> set it to the caller namespace
soinfo* caller_soinfo = find_containing_library(caller_addr);
parent_namespace = caller_soinfo != nullptr ?
caller_soinfo->get_primary_namespace() :
g_anonymous_namespace;
}
ProtectedDataGuard guard;
std::vector<std::string> ld_library_paths;
std::vector<std::string> default_library_paths;
std::vector<std::string> permitted_paths;
parse_path(ld_library_path, ":", &ld_library_paths);
parse_path(default_library_path, ":", &default_library_paths);
parse_path(permitted_when_isolated_path, ":", &permitted_paths);
android_namespace_t* ns = new (g_namespace_allocator.alloc()) android_namespace_t();
ns->set_name(name);
ns->set_isolated((type & ANDROID_NAMESPACE_TYPE_ISOLATED) != 0);
ns->set_exempt_list_enabled((type & ANDROID_NAMESPACE_TYPE_EXEMPT_LIST_ENABLED) != 0);
ns->set_also_used_as_anonymous((type & ANDROID_NAMESPACE_TYPE_ALSO_USED_AS_ANONYMOUS) != 0);
if ((type & ANDROID_NAMESPACE_TYPE_SHARED) != 0) {
// append parent namespace paths.
std::copy(parent_namespace->get_ld_library_paths().begin(),
parent_namespace->get_ld_library_paths().end(),
back_inserter(ld_library_paths));
std::copy(parent_namespace->get_default_library_paths().begin(),
parent_namespace->get_default_library_paths().end(),
back_inserter(default_library_paths));
std::copy(parent_namespace->get_permitted_paths().begin(),
parent_namespace->get_permitted_paths().end(),
back_inserter(permitted_paths));
// If shared - clone the parent namespace
add_soinfos_to_namespace(parent_namespace->soinfo_list(), ns);
// and copy parent namespace links
for (auto& link : parent_namespace->linked_namespaces()) {
ns->add_linked_namespace(link.linked_namespace(), link.shared_lib_sonames(),
link.allow_all_shared_libs());
}
} else {
// If not shared - copy only the shared group
add_soinfos_to_namespace(parent_namespace->get_shared_group(), ns);
}
ns->set_ld_library_paths(std::move(ld_library_paths));
ns->set_default_library_paths(std::move(default_library_paths));
ns->set_permitted_paths(std::move(permitted_paths));
if (ns->is_also_used_as_anonymous() && !set_anonymous_namespace(ns)) {
DL_ERR("failed to set namespace: [name=\"%s\", ld_library_path=\"%s\", default_library_paths=\"%s\""
" permitted_paths=\"%s\"] as the anonymous namespace",
ns->get_name(),
android::base::Join(ns->get_ld_library_paths(), ':').c_str(),
android::base::Join(ns->get_default_library_paths(), ':').c_str(),
android::base::Join(ns->get_permitted_paths(), ':').c_str());
return nullptr;
}
return ns;
}
bool link_namespaces(android_namespace_t* namespace_from,
android_namespace_t* namespace_to,
const char* shared_lib_sonames) {
if (namespace_to == nullptr) {
namespace_to = &g_default_namespace;
}
if (namespace_from == nullptr) {
DL_ERR("error linking namespaces: namespace_from is null.");
return false;
}
if (shared_lib_sonames == nullptr || shared_lib_sonames[0] == '\0') {
DL_ERR("error linking namespaces \"%s\"->\"%s\": the list of shared libraries is empty.",
namespace_from->get_name(), namespace_to->get_name());
return false;
}
std::vector<std::string> sonames = android::base::Split(shared_lib_sonames, ":");
std::unordered_set<std::string> sonames_set(std::make_move_iterator(sonames.begin()),
std::make_move_iterator(sonames.end()));
ProtectedDataGuard guard;
namespace_from->add_linked_namespace(namespace_to, std::move(sonames_set), false);
return true;
}
bool link_namespaces_all_libs(android_namespace_t* namespace_from,
android_namespace_t* namespace_to) {
if (namespace_from == nullptr) {
DL_ERR("error linking namespaces: namespace_from is null.");
return false;
}
if (namespace_to == nullptr) {
DL_ERR("error linking namespaces: namespace_to is null.");
return false;
}
ProtectedDataGuard guard;
namespace_from->add_linked_namespace(namespace_to, std::unordered_set<std::string>(), true);
return true;
}
ElfW(Addr) call_ifunc_resolver(ElfW(Addr) resolver_addr) {
if (g_is_ldd) return 0;
ElfW(Addr) ifunc_addr = __bionic_call_ifunc_resolver(resolver_addr);
LD_DEBUG(calls, "ifunc_resolver@%p returned %p",
reinterpret_cast<void *>(resolver_addr), reinterpret_cast<void*>(ifunc_addr));
return ifunc_addr;
}
const version_info* VersionTracker::get_version_info(ElfW(Versym) source_symver) const {
if (source_symver < 2 ||
source_symver >= version_infos.size() ||
version_infos[source_symver].name == nullptr) {
return nullptr;
}
return &version_infos[source_symver];
}
void VersionTracker::add_version_info(size_t source_index,
ElfW(Word) elf_hash,
const char* ver_name,
const soinfo* target_si) {
if (source_index >= version_infos.size()) {
version_infos.resize(source_index+1);
}
version_infos[source_index].elf_hash = elf_hash;
version_infos[source_index].name = ver_name;
version_infos[source_index].target_si = target_si;
}
bool VersionTracker::init_verneed(const soinfo* si_from) {
uintptr_t verneed_ptr = si_from->get_verneed_ptr();
if (verneed_ptr == 0) {
return true;
}
size_t verneed_cnt = si_from->get_verneed_cnt();
for (size_t i = 0, offset = 0; i<verneed_cnt; ++i) {
const ElfW(Verneed)* verneed = reinterpret_cast<ElfW(Verneed)*>(verneed_ptr + offset);
size_t vernaux_offset = offset + verneed->vn_aux;
offset += verneed->vn_next;
if (verneed->vn_version != 1) {
DL_ERR("unsupported verneed[%zd] vn_version: %d (expected 1)", i, verneed->vn_version);
return false;
}
const char* target_soname = si_from->get_string(verneed->vn_file);
// find it in dependencies
soinfo* target_si = si_from->get_children().find_if(
[&](const soinfo* si) { return strcmp(si->get_soname(), target_soname) == 0; });
if (target_si == nullptr) {
DL_ERR("cannot find \"%s\" from verneed[%zd] in DT_NEEDED list for \"%s\"",
target_soname, i, si_from->get_realpath());
return false;
}
for (size_t j = 0; j<verneed->vn_cnt; ++j) {
const ElfW(Vernaux)* vernaux = reinterpret_cast<ElfW(Vernaux)*>(verneed_ptr + vernaux_offset);
vernaux_offset += vernaux->vna_next;
const ElfW(Word) elf_hash = vernaux->vna_hash;
const char* ver_name = si_from->get_string(vernaux->vna_name);
ElfW(Half) source_index = vernaux->vna_other;
add_version_info(source_index, elf_hash, ver_name, target_si);
}
}
return true;
}
template <typename F>
static bool for_each_verdef(const soinfo* si, F functor) {
if (!si->has_min_version(2)) {
return true;
}
uintptr_t verdef_ptr = si->get_verdef_ptr();
if (verdef_ptr == 0) {
return true;
}
size_t offset = 0;
size_t verdef_cnt = si->get_verdef_cnt();
for (size_t i = 0; i<verdef_cnt; ++i) {
const ElfW(Verdef)* verdef = reinterpret_cast<ElfW(Verdef)*>(verdef_ptr + offset);
size_t verdaux_offset = offset + verdef->vd_aux;
offset += verdef->vd_next;
if (verdef->vd_version != 1) {
DL_ERR("unsupported verdef[%zd] vd_version: %d (expected 1) library: %s",
i, verdef->vd_version, si->get_realpath());
return false;
}
if ((verdef->vd_flags & VER_FLG_BASE) != 0) {
// "this is the version of the file itself. It must not be used for
// matching a symbol. It can be used to match references."
//
// http://www.akkadia.org/drepper/symbol-versioning
continue;
}
if (verdef->vd_cnt == 0) {
DL_ERR("invalid verdef[%zd] vd_cnt == 0 (version without a name)", i);
return false;
}
const ElfW(Verdaux)* verdaux = reinterpret_cast<ElfW(Verdaux)*>(verdef_ptr + verdaux_offset);
if (functor(i, verdef, verdaux) == true) {
break;
}
}
return true;
}
ElfW(Versym) find_verdef_version_index(const soinfo* si, const version_info* vi) {
if (vi == nullptr) {
return kVersymNotNeeded;
}
ElfW(Versym) result = kVersymGlobal;
if (!for_each_verdef(si,
[&](size_t, const ElfW(Verdef)* verdef, const ElfW(Verdaux)* verdaux) {
if (verdef->vd_hash == vi->elf_hash &&
strcmp(vi->name, si->get_string(verdaux->vda_name)) == 0) {
result = verdef->vd_ndx;
return true;
}
return false;
}
)) {
// verdef should have already been validated in prelink_image.
async_safe_fatal("invalid verdef after prelinking: %s, %s",
si->get_realpath(), linker_get_error_buffer());
}
return result;
}
// Validate the library's verdef section. On error, returns false and invokes DL_ERR.
bool validate_verdef_section(const soinfo* si) {
return for_each_verdef(si,
[&](size_t, const ElfW(Verdef)*, const ElfW(Verdaux)*) {
return false;
});
}
bool VersionTracker::init_verdef(const soinfo* si_from) {
return for_each_verdef(si_from,
[&](size_t, const ElfW(Verdef)* verdef, const ElfW(Verdaux)* verdaux) {
add_version_info(verdef->vd_ndx, verdef->vd_hash,
si_from->get_string(verdaux->vda_name), si_from);
return false;
}
);
}
bool VersionTracker::init(const soinfo* si_from) {
if (!si_from->has_min_version(2)) {
return true;
}
return init_verneed(si_from) && init_verdef(si_from);
}
// TODO (dimitry): Methods below need to be moved out of soinfo
// and in more isolated file in order minimize dependencies on
// unnecessary object in the linker binary. Consider making them
// independent from soinfo (?).
bool soinfo::lookup_version_info(const VersionTracker& version_tracker, ElfW(Word) sym,
const char* sym_name, const version_info** vi) {
const ElfW(Versym)* sym_ver_ptr = get_versym(sym);
ElfW(Versym) sym_ver = sym_ver_ptr == nullptr ? 0 : *sym_ver_ptr;
if (sym_ver != VER_NDX_LOCAL && sym_ver != VER_NDX_GLOBAL) {
*vi = version_tracker.get_version_info(sym_ver);
if (*vi == nullptr) {
DL_ERR("cannot find verneed/verdef for version index=%d "
"referenced by symbol \"%s\" at \"%s\"", sym_ver, sym_name, get_realpath());
return false;
}
} else {
// there is no version info
*vi = nullptr;
}
return true;
}
static void apply_relr_reloc(ElfW(Addr) offset, ElfW(Addr) load_bias) {
ElfW(Addr) address = offset + load_bias;
*reinterpret_cast<ElfW(Addr)*>(address) += load_bias;
}
// Process relocations in SHT_RELR section (experimental).
// Details of the encoding are described in this post:
// https://groups.google.com/d/msg/generic-abi/bX460iggiKg/Pi9aSwwABgAJ
bool relocate_relr(const ElfW(Relr)* begin, const ElfW(Relr)* end, ElfW(Addr) load_bias) {
constexpr size_t wordsize = sizeof(ElfW(Addr));
ElfW(Addr) base = 0;
for (const ElfW(Relr)* current = begin; current < end; ++current) {
ElfW(Relr) entry = *current;
ElfW(Addr) offset;
if ((entry&1) == 0) {
// Even entry: encodes the offset for next relocation.
offset = static_cast<ElfW(Addr)>(entry);
apply_relr_reloc(offset, load_bias);
// Set base offset for subsequent bitmap entries.
base = offset + wordsize;
continue;
}
// Odd entry: encodes bitmap for relocations starting at base.
offset = base;
while (entry != 0) {
entry >>= 1;
if ((entry&1) != 0) {
apply_relr_reloc(offset, load_bias);
}
offset += wordsize;
}
// Advance base offset by 63 words for 64-bit platforms,
// or 31 words for 32-bit platforms.
base += (8*wordsize - 1) * wordsize;
}
return true;
}
// An empty list of soinfos
static soinfo_list_t g_empty_list;
bool soinfo::prelink_image() {
if (flags_ & FLAG_PRELINKED) return true;
/* Extract dynamic section */
ElfW(Word) dynamic_flags = 0;
phdr_table_get_dynamic_section(phdr, phnum, load_bias, &dynamic, &dynamic_flags);
/* We can't log anything until the linker is relocated */
bool relocating_linker = (flags_ & FLAG_LINKER) != 0;
if (!relocating_linker) {
LD_DEBUG(any, "[ Linking \"%s\" ]", get_realpath());
LD_DEBUG(any, "si->base = %p si->flags = 0x%08x", reinterpret_cast<void*>(base), flags_);
}
if (dynamic == nullptr) {
if (!relocating_linker) {
DL_ERR("missing PT_DYNAMIC in \"%s\"", get_realpath());
}
return false;
} else {
if (!relocating_linker) {
LD_DEBUG(dynamic, "dynamic section @%p", dynamic);
}
}
#if defined(__arm__)
(void) phdr_table_get_arm_exidx(phdr, phnum, load_bias,
&ARM_exidx, &ARM_exidx_count);
#endif
TlsSegment tls_segment;
if (__bionic_get_tls_segment(phdr, phnum, load_bias, &tls_segment)) {